Title of Invention	RESIN COATED METAL PLATE AND A SURFACE-TREATING COMPOSITION FOR PRODUCING THE SAME
Abstract	A resin-coated metal plate having a resin film obtained with a surface-treating composition, the surface-treating composition comprising: an olefin-α, β-unsaturated carboxylic acid copolymer and an α, β-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass; and colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the polymers and silica), and additionally a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the polymers and silica, a content ratio of the olefin-α, β-unsaturated carboxylic acid copolymer to the α, β-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass.

Title of Invention

RESIN COATED METAL PLATE AND A SURFACE-TREATING COMPOSITION FOR PRODUCING THE SAME

Abstract

A resin-coated metal plate having a resin film obtained with a surface-treating composition, the surface-treating composition comprising: an olefin-α, β-unsaturated carboxylic acid copolymer and an α, β-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass; and colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the polymers and silica), and additionally a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the polymers and silica, a content ratio of the olefin-α, β-unsaturated carboxylic acid copolymer to the α, β-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass.

Full Text	DESCRIPTION Resin coated metal plate and a surface-treating composition for producing the same Technical Field [0001] The present invention relates to a resin-coated metal plate having a coated resin film for use, for example in automobiles, electronics appliances, building materials, and others and a surface-treating composition for production thereof, and, in particular, to a resin-coated metal plate superior in corrosion resistance, adhesiveness between the resin film and the other coated film (may be referred to as "coated film adhesiveness"), and adhesiveness between the resin film and the metal plate (may be referred to as "resin film adhesiveness") and a surface-treating composition for production thereof. Background Art [0002] Zinc-coated plating steel sheets such as electrolytic zinc-coated steel sheet and hot-dip zinc-coated steel sheet and inorganic surface-finished steel plates such as zinc-coated steel sheets additionally treated with chromate for further improvement in corrosion resistance have been used as materials for use in automobiles and the like. However, the demand for steel plates without chromate treatment is expanding because of recent increasing concern about environment. [0003] Patent Document 1 proposes a metal surface-treating agent containing an emulsion of a copolymer of a, \|3-ethylenic unsaturated carboxylic acid and olefin and a crosslinking agent, as a means of replacing the chromate treatment for improvement in corrosion resistance. Alternatively, Patent Document 2 proposes surface-treating agent containing a carboxyl group-containing resin and an inorganic silicate and a surface-finished steel plate obtained by using the same. Patent Document 1: Japanese Unexamined Patent Publication No. 2005-220,237 Patent Document 2; Japanese Unexamined Patent Publication No. 2000-282,254 Disclosure of Invention Technical Problems to be Solved [0004] However, there is recently a demand for a resin-coated steel plate having higher corrosion resistance without chromate treatment, and thus, there is a consistent need for a means of improving the corrosion resistance in the field of the resin-coated metal plate. Accordingly, an object of the present invention is to provide a resin- coated metal plate superior in corrosion resistance. Means to Solve the Problems [0005] The resin-coated metal plate according to the present invention, which achieves the object above, is a resin-coated metal plate having a resin film obtained with a surface-treating composition, the surface-treating composition comprising: an olefin-a,^-unsaturated carboxylic acid copolymer and an a, fJ-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass; and colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the olef in-a, p.-unsaturated carboxylic acid copolymer, the a, p-unsaturated carboxylic acid polymer and the colloidal silica); and additionally a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the a, jj-unsaturated carboxylic acid polymer and the colloidal silica, a content ratio of the olefin-a,^-unsaturated carboxylic acid copolymer to the a., p-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass. [0006] Preferably in the resin-coated metal plate according to the present invention, (1) the a,p-unsaturated carboxylic acid polymer is polymaleic acid; (2) the surface area-average particle size of the colloidal silica is 4 to 20 nm; and/or (3) the silane-coupling agent is a glycidyl group-containing silane-coupling agent. [0007] In a favorable embodiment of the invention, the surface-treating composition further comprises (a) a vanadium compound in an amount of 0.5 to 6 parts by mass with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the a,p-unsaturated carboxylic acid polymer and the colloidal silica, and/or (b> a carbodiimide group-containing compound in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of the total of the olef in-a, (3-unsaturated carboxylic acid copolymer and the a,p-unsaturated carboxylic acid polymer. Favorably in the resin-coated metal plate according to the present invention, the amount of the resin film coated is 0.2 to 3 g/m2 as dry mass. [0008] The present invention also provides a surface-treating composition, comprising: an olef in-a, (3-unsaturated carboxylic acid copolymer and an a,^-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass;, and colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the olef in-a, p-unsaturated carboxylic acid copolymer, the a, (5- unsaturated carboxylic acid polymer and the colloidal silica); and additionally, a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-a,^-unsaturated carboxylic acid copolymer, the a, (^-unsaturated carboxylic acid polymer and the colloidal silicar a content ratio of the olefin-a,0-unsaturated carboxylic acid copolymer to the a,p-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass. The surface-treating composition may contain additionally a vanadium compound in an amount of 0.5 to 6 parts by mass, and/or an oxazoline-containing polymer in an amount of 1 to 9 parts by mass, and/or spherical polyethylene wax particles having an average particle size of 0.6 to 4 ^m in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the total of the olefin-a,^-unsaturated carboxylic acid copolymer, the ex, p-unsaturated carboxylic acid polymer and the colloidal silica. Effect of Invention [0009] Surprisingly, combined use of an olefin-a,p- unsaturated carboxylic acid copolymer and an a, {5- unsaturated carboxylic acid polymer resulted in drastic improvement in corrosion resistance of resin-coated metal plate. Best Mode for Carrying Out the Invention [0010] An aspect of the present invention.is a surface-treating composition, comprising combination of an olefin-a,p-unsaturated carboxylic acid copolymer (hereinafter, may be referred to as "olefin-acid copolymer") and a a,p-unsaturated carboxylic acid polymer (hereinafter, may be referred to as "carboxylic acid polymer"). As shown in the Examples below, the resin-coated metal plate obtained by applying and drying a surface-treating composition containing both of them on a metal plate is significantly improved in corrosion resistance in comparison with a resin-coated metal plate obtained with a surface-treating composition containing only one of them. [ODll] In the invention, the "olefin-a,p-unsaturated carboxylic acid copolymer" or the "olefin-acid copolymer" is copolymer of an olefin and an a, ^-unsaturated carboxylic acid, and the content of the olefin-derived constituent unit is 50 % by mass or more (i.e., the content of the a,(5-unsaturated carboxylic acid-derived constituent unit is 50 % by mass or less) in the copolymer; and the "a,(S-unsaturated carboxylic acid polymer" or the "carboxylic acid polymer" is a polymer obtained from a monomer a,p-unsaturated carboxylic acid, and the content of the oc, p-unsaturated carboxylic acid-derived constituent unit in the polymer is 90 % by mass or more. In the Examples below, an "ethylene-acrylic acid copolymer" was used as "olefin-acid copolymer", and "polymaleic acid" or "polyacrylic acid" was used as "carboxylic acid polymer". [0012] Although the accurate mechanism for the fact that the corrosion resistance of a resin-coated metal plate is improved by surface treatment with a composition containing both an olefin-acid copolymer and a carboxylic acid polymer is yet to be understood, it seems that a dense resin film that effectively inhibits permeation of water and oxygen is formed by combined use of these resins. However, the present invention is not restricted by the reasoning. [0013] The olefin-acid copolymer for use in the present invention can be prepared by copolymerization of an olefin and an a,^-unsaturated carboxylic acid by a known method, and it is also commercially available. One or more olefin-acid copolymers may be used in the invention. [0014] The olefin for use in production of the olefin-acid copolymer is not particularly limited, but preferably ethylene, propylene, or the like, and more preferably ethylene. Either an olefin-acid copolymer containing a ,single olefin constituent unit or that containing two or more olefin constituent units may be used as olefin-acid copolymer. [0015] The a, \|5-unsaturated carboxylic acid for use in production of the oiefin-acid copolymer is also not particularly limited, but examples thereof include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and the like. Among the acids above, acrylic acid is preferable. Either an clefin-acid copolymer containing only one a,p-unsaturated carboxylic acid constituent unit or that containing two or more a,p-unsaturated carboxylic acid constituent units may be used as olefin-acid copolymer. [0016] The olefin-acid copolymer for use in the present invention may contain an other iivonomer-derived constituent unit in such a range as does not impair the advantageous effects of the present invention, i.e., corrosion resistance and others. The content of the other monomer-derived constituent unit in the olefin-acid copolymer is preferably 10 % by mass or less, more preferably 5 % by mass or less, and the most favorable olefin-acid copolymer is prepared only with an olefin and an a,^"Unsaturated carboxylic acid. A favorable olefin-acid copolymer is, for example, an ethylene-acrylic acid copolymer. [0017] The a,p-unsaturated carboxylic acid constituent unit in the olefin-acid copolymer is used for improving adhesiveness between the resin film and the metal plate and securing the amount of carboxyl groups for crosslinking reaction. The content of the a,p-unsaturated carboxylic acid constituent unit in the copolymer is preferably 5 % by mass or more, more preferably 10 % by mass or more. However, an excessive content of the a,p-unsaturated carboxylic acid unit may lead to deterioration in corrosion resistance and alkali resistance, and thus, the constituent unit content is preferably 30 % by mass or less, more preferably 25 % by mass or less. [0018] The weight-average molecular weight of the olefin-acid copolymer for use in the present invention is preferably 1,000 to 100,000, more preferably 3,000 to 70,000, and still more preferably 5,000 to 30,000. The weight-average molecular weight can be determined by GPC by using styrene as standard. [0019] A homopolymer, a copolymer of one or more a,p-unsaturated carboxylic acids, or a copolymer containing another additional monomer may be used as carboxylic acid polymer. The carboxylic acid polymer can be prepared by a known method and is also commercially available. In the present invention, one or more carboxylic acid polymers may be used. [0020] The a,p-unsaturated carboxylic acid for use in production of the carboxylic acid polymer is not particularly limited, and examples thereof include monocarboxylic acids such as acrylic acid, methacrylic acid. crotonic acid, and isocrotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and the like. Among them, acrylic acid and maleic acid are preferable, and maleic acid is more preferable. [0021] The carboxylic acid polymer may contain a constituent unit derived from a monomer other than a,^-unsaturated carboxylic acids above, but the content of the other monomer-derived constituent unit in the polymer is 10 % by mass or less, preferably 5 % by mass or less, and the polymer is preferably a carboxylic acid polymer constituted only by an a, (5-unsaturated carboxylic acid. Favorable examples of the carboxylic acid polymers include polyacrylic acid, polymethacrylic acid, acrylic acid-malic acid copolymers, polymaleic acid, and the like, and among them polymaleic acid is more preferable from the viewpoints of coated film adhesiveness, resin film adhesiveness and corrosion resistance. Although, the accurate mechanism for the improvement in corrosion resistance by use of the polymaleic acid is not clear, it seems that presence of carboxyl groups in a greater amount leads to improvement in adhesiveness between the resin film and the metal plate and also in corrosion resistance. However, the present invention is not restricted by the reasoning. [0 022] The weight-average molecular weight of the carboxylic acid polymer for use in the present invention is preferably 500 to 30,000, more preferably 800 to 10,000, still more preferably 900 to 3,000, and most preferably 1,000 to 2,000. The weight-average molecular weight can be determined by GPC, by using styrene as standard. [0023] The content ratio of the olefin-acid copolymer to the carboxylic acid polymer in the surface-treating composition is 1,000: 1 to 10: 1, preferably 200: 1 to 20: 1, and more preferably 100: 1 to 100: 3. An excessively smaller content ratio of the carboxylic acid polymer may lead to restriction of the advantageous effects of using the olefin-acid copolymer and the carboxylic acid polymer in combination, while an excessively large content ratio of the carboxylic acid polymer may lead to phase separation between the olefin-acid copolymer and the carboxylic acid polymer in the surface-treating composition, possibly prohibiting production of a uniform resin film and causing deterioration in alkali resistance. [0024] It is one of characteristics that the surface-treating composition according to the present invention contains colloidal silica. Presence of the colloidal silica in the resin film prevents erosion of the metal plate under corrosive environment by elution of silica and improves the corrosion resistance of the metal plate. [0025] Colloidal silicas are coitimercially available, and any common commercial product may be used. Examples of the colloidal silica products include Snowtex series products such as "ST-40", "ST-XS", "ST-N", "ST-SS", and "ST-0" manufactured by Nissan Chemical Industries, Ltd., and the like. When the surface-treating composition used in forming the resin film is an aqueous composition, the kind of the colloidal silica is preferably selected properly according to the pH of the surface-treating composition, for favorable dispersion of the colloidal silica. [002 6] In the surface-treating composition, the total amount of the olefin-acid copolymer and the carboxylic acid polymer (hereinafter, may be referred to as "resin component") is 55 to 95 parts by mass, and the amount of the colloidal silica is 5 to 45 parts by mass (with respect to the 100 parts by mass of the total of the resin component and the colloidal silica). The amounts of the resin component and the colloidal silica specified in the present invention are values as solid m.atter. [0027] A colloidal silica amount of more than 45 parts by mass leads to decrease in resin component and thus to deterioration of film-forming properties of the surface-treating composition, resulting in cracking of the resin film and deterioration in corrosion resistance and other properties. The amount of the colloidal silica is preferably 30 parts by mass or less, and more preferably 25 parts by mass or less from the viewpoint of spot welding property (wherein, the total of the resin component and the colloidal silica is 100 parts by mass). A colloidal silica amount of 25 parts by mass or less prevents accumulation of silica on the electrode during spot welding effectively. [0028] On the other hand, a colloidal silica amount of less than 5 parts by mass leads to insufficient effect of improving corrosion resistance of colloidal silica and also to deterioration in alkali resistance. The amount of the colloidal silica is preferably 10 parts by mass or more, more preferably 15 parts by mass or more {with respect to 100 parts by mass of the total of the resin component and the colloidal silica). [0029] When excessively larger in size, the colloidal silica for use in the present invention leads to deterioration in film-forming properties of the surface-treating composition, insufficient silica elution under corrosive enviroimient, and insufficient improvement of corrosion resistance. It also leads to deterioration in alkali resistance and resin film adhesiveness. On the other hand, when the colloidal silica is too small in size, the improvement in corrosion resistance is saturated, and the silica becomes too active, causing gelation of the surface-treating composition and prohibiting production of a favorable resin film. Thus, the surface area-average particle size of the colloidal silica is preferably 4 to 20 nm. The "surface area-average particle size of silica" may be determined by the Shears method when the average particle size is about 1 to 10 nm and by the BET method when it is about 10 to 100 nm. [0030] It is also one of characteristics of the present invention, the surface-treating composition according to the present invention contains a silane-coupling agent. Use of a silane-coupling agent improves adhesiveness between the metal and the resin film and also corrosion resistance. Thus, there is no need for addition of an acidic compound for etching the surface of the metal plate to the surface-treating composition {e.g., phosphoric acid compound, nitric acid compound or fluorine compound). It is because it is possible to improve the resin film adhesiveness with the silane-coupling agent even when the metal plate surface is not etched. A surface-treating composition for etching containing no acidic compound is improved in stability and gives a favorable resin film. [0031] The content of the silane-coupling agent in the surface-treating composition is 7 parts or more, preferably 9 parts or more, more preferably 11 parts by mass or more, and 30 parts or less, preferably 25 part or less by mass, with respect to 100 parts by mass of the total of the olefin-acid copolymer, the carboxylic acid polymer and the colloidal silica. A silane-coupling agent content of less than 7 parts by mass leads to deterioration in resin film adhesiveness and corrosion resistance, while that of more than 30 parts by mass/ to deterioration in stability of the surface-treating composition and thus, to deterioration in adhesiveness and corrosion resistance. [0032] The silane-coupling agents are commercially available, and a common commercial product may be used in . the invention. A single or plural silane-coupling agents may be used. Examples of the silane-coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(p-methoxyethoxy)silane, y- chloropropylmethoxysilane, Y~aminopropyl triethoxysilane, N-(p-aminoethyl)-Y-aminopropyltrimethoxysilane, N-(p-aminoethyl)-Y-aminopropylmethyldimethoxysilane, y-methacryloxypropyltrimethoxysilane, y-mercaptopropyltrimethoxysilane, and the like. [0033] Among the silane-coupling agents above, preferable are glycidyl group-containing silane-coupling agents. Such a glycidyl group-containing silane-coupling agent is highly reactive and thus is effective in improving corrosion resistance and alkali resistance. Examples of the glycidyl group-containing silane-coupling agents include ygiycidoxypropyltrimethoxysilane, y-glycidoxytnethyldimethoxysilane, and the like. [0034] The surface-treating composition according to the present invention may contain a vanadium compound. The vanadium compound also prohibits erosion of the metal plate and improves corrosion resistance thereof, by elution thereof similarly to colloidal silica. The vanadium compound improves the corrosion resistance of steel sheet, and in particular the corrosion resistance in the damage area, especially when the metal plate is a hot-dip zinc-coated steel sheet or an electrolytic zinc-coated steel sheet. [0035] Examples of the vanadium compounds include vanadium pentoxide (V2O5) / ammonium metavanadate {NH4VO3) , sodium metavanadate (NaVOa) 1 potassium metavanadate (KVO3) , vanadium acetylacetonate (V (CsHiOz) 3) / and the like, and these compounds may be used alone or in combination of two or more. These vanadium compounds are commercially available and thus, easily available, [003 6] When the surface-treating composition according to the present invention is an aqueous composition, "Vanadic Acid Solution (IV)" highly soluble in water (aqueous solution containing VaOs reduced to tetravalent with oxalic acid) manufactured by Shinko Chemical Co., Ltd is preferably used as a vanadium compound. When the aqueous surface-treating composition is neutral or alkaline, the vanadic acid solution is preferably neutralized to pH 5 to 7 with a base {preferably with ammonia water) before use (the pH of commercially available "Vanadic Acid Solution (IV)" is approximately 3). However, the vanadic acid solution, when the pH thereof is more than 7, may generate fine suspended matter of vanadium hydroxide. [0037] The content of vanadium compound in the surface-treating composition is preferably 0.5 to 6 parts by mass, more preferably 1 to 3 parts by mass, with respect to 100 parts by mass of the total of the olefin-acid copolymer, the carboxylic acid polymer and the colloidal silica. A vanadium compound content of less than 0.5 part by mass results in insufficient improvement of corrosion resistance. On the other hand, a content of more than 6 parts by mass leads to saturation of the improvement in corrosion resistance and yet to deterioration in coated film adhesiveness and resin film adhesiveness. When the "Vanadic Acid Solution" is used, the vanadium compound content specified in the present invention is the V2O5 amount calculated from the V2O5 concentration in "Vanadic Acid Solution" (provided form the manufacturer). [003 8] The surface-treating composition according to the present invention may contain a carbodiimide group-containing compound additionally. The carbodiimide group in the compound reacts with the carboxyl group in the olefin-acid copolymer and carboxylic acid polymer. Thus, it is possible to reduce the amount of carboxyl groups in the resin film and improve alkali resistance by using such a carbodiimide group-containing compound. A single or plural carbodiimide group-containing compounds may be used in the invention. [0039] The carbodiimide group-containing compound is prepared, for example, by heating an isocyanate, such as hexamethylene diisocyanate {HDD, xylylene diisocyanate {XDI), hydrogenated xylylene diisocyanate (HXDI), 4,4-diphenylmethane diisocyanate (MDI) or tolylene diisocyanate (TDI), in the presence of a carbodiimidation catalyst, and may be made more hydrophilic (water-soluble, water-emulsifiable or water-dispersible) by modification. When the surface-treating composition is an aqueous composition, an aqueous carbodiimide group-containing compound is preferable. A compound having plural carbodiimide groups in the molecule is also preferable. Presence of plural carbodiimide groups in the molecule improves corrosion resistance further by crosslinking reaction with the carboxyl groups in the resin component. [0040] Examples of the commercially available polycarbodiimide compounds include N,N- dicyclohexylcarbodiimide, N,N-diisopropylcarbodiimide and "polycarbodiimides" manufactured by Nisshinbo Industries, Inc. (a polymer having plural carbodiimide groups in the molecule), and, among them, "polycarbodiimides" containing plural carboxyi groups is preferable. [0041] For sufficient expression of the advantageous effects of the carbodiimide group-containing compound, the content of the compound in the surface-treating composition is preferably 0.1 part by mass or laore, more preferably 0.5 part by mass or more, and more preferably 8 parts by mass or more, with respect to 100 parts by mass of the olefin-acid copolymer and carboxylic acid polymer. On the other hand, an excessive content of the carbodiimide group-containing compound leads to decrease of the combined effects of the olefin-acid copolymer and the carboxylic acid polymer. Alternatively, use of an aqueous carbodiimide group-containing componnd in an excessive amount in the aqueous surface-treating composition may give adverse effects on water resistance and corrosion resistance. From the viewpoint above, the content of the carbodiimide group-containing compound is preferably 30 parts by mass or less, more preferably 20 parts or less, and still more preferably 16 part by mass or less, with respect to 100 parts by mass of the substances above. [0042] The surface-treating composition according to the present invention may contain a resin and/or a wax other than the olefin-acid copolymer and carboxylic acid polymer in an amount in the range that does not impair the advantageous effects of the present invention. The total amount of the other resin and wax in the surface-treating composition is preferably 10 parts by mass or lesSr more preferably 5 parts by mass or less, with respect to 100 parts by mass of the olefin-acid copolymer and carboxylic acid polymer. The surface-treating composition may contain other compounds such as crosslinking agent, diluent, skinning inhibitor, surfactant, emulsifier, dispersant, leveling agent, antifoam, penetrant, filming aid, dye, pigment, thickener and lubricant in such a range as does not impair the advantageous effects of the present invention. The surface-treating composition according to the present invention may additionally contain an oxazoline-containing polymer in an amount of 1 to 9 parts by mass with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the o(, p-unsaturated carboxylic acid polymer and the colloidal silica. The oxazoline-containing polymer allows low-temperature drying, gives a surface-treating composition resistance to deterioration in flowability (viscosity) and wettability and also superior in mechanical stability. Use of an oxazoline-containing polymer, which has a styrene/acrylic polymer main chain, gives a very hard film that is favorably adhesive to the base material and the post-coating film (favorable in resin film adhesiveness & coated film adhesiveness). Thus, the film is more resistant to damage, even when a resin-coated metal plate is subjected to roll molding, which leads to separation of its film more frecpaently than press molding. Examples of the oxazoline-containing polymers include "Epocros K series" products manufactured by Nippon Shokubai Co., Ltd., i.e., styrene/acrylic emulsions, such as "K-2010E", "K-2020E", and "K-2030E", and the like. When the content of the oxazoline-containing polymer is 1 part by mass or less with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the a,^-unsaturated carboxylic acid polymer and the colloidal silica, there is no improvement in the hardness of the film, and the film is pressurized and broken by contact with the roll during roil molding, resulting in stripping of the film. When the content of the oxazoline-containing polymer is not less than 9 parts by mass with respect to 100 parts by mass of the total of the olef in-a, (3-unsaturated carboxylic acid copolymer, the a,p-unsaturated carboxylic acid polymer and the colloidal silica, there is no further improvement of the film, and the coated film adhesiveness is deteriorated significantly. The content is preferably 2 to 6 parts by mass, more preferably 3 to 4 parts by mass. The surface-treating composition according to the present invention may contain spherical polyethylene wax particles having an average particle size of 0.6 to 4 jjia in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the total of the olefin-a,^-unsaturated carboxylic acid copolymer, the a,p-unsaturated carboxylic acid polymer and the colloidal silica. It is thus possible to reduce the contact resistance between the roll and the resin-coated metal plate and prevent damaging of the film, when the resin-coated metal plate is subjected to roll molding. When used in combination with the oxazoline-containing polymer described above, it is possible to prevent the film damage further more effectively. Examples of the spherical polyethylene wax particles include Chemipearl products (polyolefin aqueous dispersion) manufactured by Mitsui Chemicals, Inc. such as "W-100", "W-400", "W-500", "W-700", and "W-900", and the like. Differently from during press molding, a resin-coated metal plate is molded gradually with multi-stage rolls while a coolant solution {aqueous emulsion of oil in water) is normally supplied during roll molding, and thus, there is almost no rise of the temperature of the roll or resin-coated metal plate, but it is quite important to reduce the contact resistance between the roll during molding roll and the resin-coated metal plate, by making them more lubricating to each other. It is thus necessary to disperse the spherical wax particles in the film while the shape thereof is preserved, and thus, the temperature at which the surface-treating composition is dried after application (film-forming temperature) should not be higher than the softening point of the spherical polyethylene wax particles. When the average particle size of the spherical polyethylene wax is not larger than 0.6 ]iJD.f there is no protrusion of film-coated wax particles formed on the film surface, prohibiting reduction in the contact resistance with rolls during roll molding. It is difficult to cover the wax particles having an average particle size of 4 yiti or more with the film, which may cause paint repellency during post-coating and also deterioration in the coated film adhesiveness after coating. [0043] The surface-treating composition according to the present invention may be a solvent-based composition or an aqueous composition that can be applied on the surface of a metal plate, but an aqueous composition is preferable from the point of environment problem. The method of producing the surface-treating composition is not particularly limited, and the surface-treating composition can be prepared, for example, by mixing and stirring an organic solvent (in the case of a solvent-based composition) or water, preferably deionized water (in the case of an aqueous composition) with an olefin-acid copolymer, a carboxylic acid polymer, colloidal silica and a silane-coupling agent, and as needed a vanadium compound, a carbodiimide group-containing compound and/or other component respectively in certain amounts. The mixture may be heated during agitating, but is preferably heated before addition of the silane-coupling agent and as needed the carbodiimide group compound, and not heated after addition thereof if possible, for prevention of gelation of the surface-treating composition in reaction of the olefin-acid copolymer and carboxylic acid polymer with the silane-coupling agent and the carbodiimide group-containing compound. [004 4] It is preferable to emulsify the olefin-acid copolymer, the principal component of the resin, in producing an aqueous surface-treating composition. It is possible to emulsify the olefin-acid copolymer by using an emulsifier and/or by neutralizing carboxyl groups in the copolymer.- It is possible to reduce the average particle size of the aqueous emulsion of the olefin-acid copolymer and improve the filming efficiency and thus density of the resulting resin film, by using an emulsifier. [004 5] In a favorable embodiment, the carboxyl groups in the olefin-acid copolymer are neutralized for emulsification. It is because it is possible to reduce the amount of the emulsifier used or even eliminate the emulsifier by neutralizing the carboxyl groups and to reduce or eliminate the adverse effects of the emulsifier on water resistance and corrosion resistance of resin film. In neutralizing the carboxyl groups in the olefin-acid copolymer, a base in an amount of preferably, approximately 0.5 to 0.95 equivalence, more preferably 0.6 to 0.8 equivalence, with respect to the carboxyl group is used. Insufficient neutralization leads to lower emulsification, while excessive neutralization leads to decrease in the amount of carboxyl groups reacting, for example, with the silane-coupling agent, resulting in adverse effects, for example, on corrosion resistance and increase in viscosity of the composition containing an olefin-acid copolymer. [0046] Examples of the bases for neutralization include strong bases such as hydroxides of an alkali or alkali-earth metal (such as NaOH, KOH, and Ca(0H)2, preferably NaOH); ammonia water, and primary, secondary and tertiary amines (preferably triethylamine). Use of a strong base such as NaOH leads to improvement in emulsification efficiency, but use of an excessive amount thereof may lead to deterioration in corrosion resistance of the resin film. On the other hand, amines, in particular low-boiling point amines, preferably amines having a boiling point of 100°C or lower under atmospheric pressure (e.g., triethylamine), do not cause much deterioration of corrosion resistance of resin film, possibly because the low-boiling amine is vaporized when the resin film obtained by application of a surface-treating composition is dried. However, am.ines are less effective in improving the emulsification efficiency. It is thus preferable to use a strong base and an amine in combination, preferably NaOH and triethylamine, during neutralization and emulsification of the carboxylic acid, groups in the olefin-acid copolymer. When a strong base and an amine are used in combination, the strong base is used in an amount of preferably 0.01 to 0.3 equivalence and the amine in an amount of preferably 0.4 to 0.8 equivalence with respect to the carboxylic acid amount in the olefin-acid copolymer, [0047] When an aqueous surface-treating composition is used, a small amount of organic solvent may be added for reduction of interfacial tension and improvement of the compatibility with the metal plate. Examples of the organic solvents for that purpose include methanol, ethanol, isopropanol, butanols, hexanol, 2-ethylhexanol, ethylene glycol ethylether, ethylene glycol butylether, diethylene glycol, propylene glycol, and the like. [004 8] The solid matter in the surface-treating composition is not particularly limited, and is adjusted according to the method of applying the surface-treating composition onto the metal plate. The content of the solid matter in the surface-treating composition is generally, approximately 5 to 20 % by mass, preferably approximately 10 to 18 % by mass, for example when the composition is applied by a spray Ringer method (method of spraying a surface-treating composition on a metal plate and squeezing the wet surface with a roll). [0049] The metal plate for use in the present invention is not particularly limited, and examples thereof include non-plated cold-drawn steel sheet, hot-dip zinc-coated steel sheet (GI), hot-zip alloyed zinc-coated steel sheet (GA), electrolytic zinc-coated steel sheet (EG), aluminum plate, titanium plate, and the like. Among them, zinc-coated steel sheet without chromate treatment is preferable. [0050] In the invention, the method of forming the resin film on a metal plate and the condition for it are not particularly limited, and a resin-coated metal plate may be produced by any Icnown application method of applying the surface-treating composition on one side or both surfaces of a metal plate and heating and. drying the resulting film. Examples of the methods of applying the surface-treating composition include curtain flow coater method, roll coater method, spraying method, spray Ringer method and the like, and among them, the spray Ringer method is preferable for example from the viewpoint of cost. The condition of heating and drying the composition is also not particularly limited, and the heating and drying temperature is, for example, approximately 50 to 120°C, preferably 70 to 90°C. However, an excessively high heating drying temperature is undesirable because it leads to deterioration of the resulting resin film. [0051] A excessively small amount of the resin film formed on the surface of the metal plate prohibits sufficient securement of corrosion resistance and others. On the other hand, an excessively large deposition amount is uneconomical, because of saturation of the properties such as corrosion resistance, and it may also lead to deterioration in resin film adhesiveness. Thus, the amount of the resin film formed on the resin-coated metal plate is preferably 0.2 to 3 g/m2, more preferably 0.7 to 2 g/m2 as dry mass. EXAMPLES [0052] Hereinafter, the present invention will be described more specifically with reference to Examples, but it should be understood that the present invention is not restricted by the following Examples, modifications can be made within the scope of the description above and below, and such modification are also included in the technical scope of the present invention. [0053] (1) Method of evaluating the properties of resin- coated metal plate (1-1) Flat plate corrosion resistance The period until the white rusting rate (white rust-generated area/ entire sample area XIOO) reached 5% was determined in the salt spray test according to JIS Z2371. [0054] (1-2) Crosscut corrosion resistance For determination of the corrosion resistance of damaged area, a crosscut was formed on a sample with a cutter knife, and the period until the white rusting rate reached 10% was determined according to the salt spray specified in JIS Z2371. [0055] (1-3) Corrosion resistance by JASO cycle test The JASO cycle test [a cycle of salt spraying (at 35°C for 2 hours)— drying (at 35°C and 30% humidity or less for 4 hours)-* moisturizing (at SCc and 95% humidity or more for 2 hours, respectively including transferring periods)] was performed for 15 cycles according to JIS K8502, and the white rusting rate was evaluated according to the following criteria: (Evaluation criteria) @: White rusting rate: less than 5% O: White rusting rate: 5% or more and less than 10% A: White rusting rate: 10% or more and less than 20% x; White rusting rate: 20% or more [0056] (1-4) Coated film adhesiveness An acrylic paint was applied for post coating on a sample to a layer thickness of 20 ]im by bar coating, baked at a temperature of 160°C for 20 minutes. Subsequently, the sample was immersed in boiling water for 1 hour, taken out, and left for 1 hour, and then, engraved in a checkerboard pattern having 100 squares at an interval of 1 mm with a cutter knife; and the number of the coated films remaining on the sample after the tape peel test was determined; and the coated film adhesiveness was evaluated according to the following criteria: (Evaluation criteria) ©: Coated film residual ratio: 100% O: Coated film residual ratio: 99% or less to 90% or more A: Coated film residual ratio: 89% or less to 80% or more X: Coated film residual ratio: 79% or less [0057] (1-5) Alkali resistance A sample was immersed in a solution containing 20 g/L of an alkaline degreasing agent (CL-N364S, manufactured by Nihon Parkerizing Co., Ltd.) at the liquid temperature kept to 60°C for two minutes, taken out, washed, and dried; and the period until the white rust rate reached 10% was determined in salt spray test according to JIS Z2371. [0058] (1-6) Resin film adhesiveness For evaluation of the adhesiveness between the resin film and the metal plate, a filament tape {#9510, manufactured by Sliontec Corporation) was bonded onto the surface of a sample; the composite was stored under the atmosphere of temperature of 40°C and RH of 98% for 168 hours; and the areal rate of the resin film remaining after removal of the filament tape was determined (residual ratio). The resin film adhesiveness was evaluated according to the following criteria: (Evaluation criteria) ®: Film residual ratio: 100% O: Film residual ratio: less than 100% and 90% or more A: Film residual ratio: less than 90% and 70% or more X; Film residual ratio: less than 70% (1-7) Roll moldability In evaluating the roll moldability, the surface.of a resin-coated metal plate was scraped with a stainless steel (SUS) protrusion (linear contact) in a roll moldability analyzer, and the resulting damage on the film was observed visually. The roll m.oldability analyzer has a flat plate dice and a dice having projections (both made of SUS steel), and a resin-coated metal plate is inserted into and withdrawn from the space between the dices under application of pressure. The size of the tested resin-coated metal plate was 40x300 ram; the withdrawal speed was 300 mm/min; and the applied pressure was 1960 N in the test. @: No observable damage on film O; Slight dam.age on film A: Some damage on film X; Some damage both on film and metal plate [0059] (2) Resin composition The resin-coated metal plate used in each Example was prepared by applying and drying a surface-treating composition on a metal plate. The surface-treating composition was prepared by preparing a composition containing an olefin-acid copolymer, a carboxylic acid polymer, and a silane-coupling agent in an amount smaller than a particular amount, and others (referred to as "resin composition" in each Example) and adding colloidal silica, the rest amount of the silane-coupling agent, and others to the resin composition. Hereinafter, the resin composition used in preparation of the surface-treating composition in each Example will be described. [0050} (2-1) Preparation of resin composition 1 To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company, acrylic acid constituent unit: 20 % by mass, weight-average molecular weight; 20,000, melt index; 1300, acid value; 150), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W" manufactured by NOF Corporation, weight-average molecular weight: approximately 1100, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6,9 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FAB", manufactured by Harima Chemicals, Inc.), and 7 92.6 g of ion-exchange water; and the mixture was sealed and agitated vigorously at 150*0 and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.4 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones, Y" glycidoxypropyltrimethoxysilane) , 31.2 g of a carbodiimide group-containing compound ("polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc. weight-average molecular weight: 2,700, solid matter 40 % by mass), and 72.8 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 1 in an aqueous emulsion form (solid matter content: 20.3 % by mass, as determined according to JIS K6833). [0061] (2-2) Preparation of resin composition 2 To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1,0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W",manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 q of aqueous 4 8% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of an a-olefin-maleic anhydride copolymer wax ("Diacarna 30", manufactured by Mitsubishi Chemical Corporation), and 792.6 g of ion-exchange water; and the mixture was sealed and stirred vigorously at 150°C and a pressure of 5 atmospheres for 3 hours and cooled to 30'C. Then, 10.4 g of a silane-coupling agent {"TSL8350", manufactured by GE Toshiba Silicones), 31.2 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02" manufactured by Nisshinbo Industries, Inc., solid matter: 40 % by mass), and 72.8 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 2 in an aqueous emulsion form (solid matter content: 2 0.1 % by mass). [0062] (2-3) Preparation of resin composition 3 To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer {"Primacor 59901", manufactured by Dow Chemical Company), 16.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W",manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of an aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FAS", manufactured by Harima Chemicals, Inc.), and 812.2 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and cooled to 30°C. Then, 10.7 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 32.2 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 75 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 3 in an aqueous emulsion form (solid matter content: 20.5 % by mass). [0063] (2-4) Preparation of resin composition 4 To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("AC5120" manufactured by Honeywell International Inc., acrylic acid constituent unit: 15 % by mass, weight-average molecular weight: 5,000, acid value: 120), 8.0 g of an aqueous polymaleic acid solution ("Nonpoi PMA-50W" manufactured by NOF Corporation, 50 % by mass), 34.6 g of triethylamine (0.8 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 5.4 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FA3", manufactured by Harima Chemicals, Inc.), and 798.9 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.5 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 31.5 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 73.5 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 4 in an aqueous emulsion form (solid matter content: 20.1 % by mass). [0064] (2-5) Preparation of resin composition 5 To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W", manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine {0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of aqueous 4 8% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid (manufactured by Harima Chemicals, Inc. "Hartall FA3"), and 774.4 g of ion-exchange water; and the mixture was sealed and agitated rapidly at ISCC and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.5 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), and 10.5 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 5 in an aqueous emulsion form (solid matter content: 21.1 % by mass). [0065] (2-6) Preparation of resin composition 6 To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA~50W",manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 5.9 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), and 788.1 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150'C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.4 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 31.2 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 72.8 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 6 in an aqueous emulsion form (solid matter content: 20.6 % by mass). [0066] (2-7) Preparation of resin composition 7 To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company ), 10.0 g of an aqueous polyacrylic acid solution ("AC-IOL", manufactured by Nihonjunyaku Co., Ltd., weight-average molecular weight: 25,000, 40 % by mass), 33.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FA3", manufactured by Hariitia Chemicals, Inc.)/ 6.9 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), and 788.1 g of ion-exchange water ; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.4 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 31.2 g of a carbodiimide group-containing compound ("Polycarbodiiitiide 5V-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 72.8 g of ion-exchange water were added thereto, and the mixture was stirred for 10 minutes, to give a resin composition 7 in an aqueous emulsion form (solid matter content: 20.2 % by mass). [00 67] (2-8) Preparation of resin composition 8 (containing no carboxylic acid polymer, for comparison) To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of aqueous 4 8% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FA3", manufactured by Harima Chemicals, Inc.), and 788.1 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.3 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 30.9 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 72.1 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 8 (for comparison) in an aqueous emulsion form (solid matter content: 2 0.0 % by mass). [0068] (2-9) Preparation of resin composition 9 (containing no carboxylic acid polymer, for comparison) To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 35.5 g of triethylamine (0.S3 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of aqueous 48% NaOH solution (0,15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), and 774.1 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.2 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones}/ 30.6 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02" manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 71.4 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 9 (for comparison) in an aqueous emulsion form {solid matter content: 19.1 % by mass). [0069] (2-10) Resin compositions 10 to 14 (for comparison) Resin composition 10 (for comparison): The polymaleic acid for resin composition 1 was replaced with an aqueous polyacrylic acid solution ("AC-IOS" manufacture by Nihonjunyaku Co., Ltd, weight-average molecular weight: 5,000, solid matter 40.3 % by mass). Resin composition 11 (for comparison): The polymaleic acid for resin composition 1 was replaced with an aqueous polymaleic acid solution {"Nonpol PMA-50W", manufactured by NOF Corporation, solid matter content: 50.1 % by mass). Resin composition 12 (for comparison): The polymaleic acid for resin composition 1 was replaced with an aqueous methylvinylether-maleic anhydride copolymer solution ("AN-119" manufactured by ISP Japan Ltd., weight-average molecular weight: 200,000, solid matter content: 15.3 % by mass) . Resin composition 13 (for comparison): The ethylene-acrylic acid copolymer for resin composition 1 was replaced with an aqueous ethylene-acrylic acid copolymer resin emulsion ("HYTEC S-3121" manufactured by Toho Chemical Industry Co., Ltd, weight-average molecular weight: 40,000, solid matter content: 25.5 % by mass). Resin composition 14 (for comparison): Triethylamine in resin composition 1 was replaced with an aqueous polyallylamine solution ("PAA-01" manufactured by Nitto Boseki Co., Ltd., weight-average molecular weight: 5,000, solid matter content: 15.1 % by mass). [0070] Example 1 A colloidal silica ("ST-XS" manufactured by Nissan Chemical Industries, Ltd, surface area-average particle size: 4 to 6 nm) was added to each of the resin compositions 1 to 14, in an amount of 20 parts by mass with respect to 80 parts by mass of the resin component therein, giving a mixture of 100 parts by mass in total. In addition, a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd, Y~ glycidoxypropyltrimethoxysilane) was added in an amount of 10 parts by mass with respect to the 100 parts by mass of the total of the mixture; the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 15 to 16.5 % by mass); and the mixture was agitated at room temperature, to give a surface-treating composition. [0071] In the Example above, the resins in the "resin component" mean an olefin-acid copolymer and a carboxylic acid polymer in resin compositions 1 to 7, an olefin-acid copolymer in resin compositions 8 and 9, and the polymers respectively contained in the resin composition in resin compositions 10 to 14. When any one of the acidic resin compositions 10 to 12 (for comparison) is used, the surface-treating composition was prepared by using an acidic colloidal silica ("ST-0" manufactured by Nissan Chemical Industries, Ltd, surface area-average particle size: 10 to 20 nm) instead of the colloidal silica "ST-XS". 10072] Resin-coated metal plates 1 to 14 each having a resin film in an coating amount of 1.0 g/m2 were prepared by using an alkaline-degreased hot-dip zinc-coated steel sheet (Zn deposition: 45 g/m2) as a metal plate, and by applying the surface-treating composition above on the surface of the steel plate by bar coating (No.3 bar) and drying the film under heat at a plate temperature of 90°C for approximately 12 seconds. [0073] The properties of the resin-coated metal plates obtained were evaluated. The results are summarized in Table 1. As shown in the following Table 1, the resin-coated metal plates 1 to 7 each obtained with a surface-treating composition containing both an olefin-acid copolymer and a carboxylic acid polymer were superior in corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness. Five to 45 parts by mass of a colloidal silica ("ST-XS", manufactured by Nissan Chemical Industries, Ltd) was added to 55 to 95 parts by mass of the resin component in the resin composition 1 above, giving a mixture of 100 parts by mass in total. Ten parts by mass of a silane-coupling agent ("KBM4 03" manufactured by Shin-Etsu Chemical Co., Ltd) was added additionally to the total 100 parts by mass thereof, and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition. [0076] Resin-coated metal plates 15 to 26 were prepared in a similar manner to Example 1, and the properties thereof were evaluated. Results are summarized in Table 2. As shown in the following Table 2, the resin-coated metal plates 15 to 23 satisfying the requirements in the amounts of resin components and colloidal silica specified in the present invention were superior in corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness. [0077) [007 8] Example 3 Twenty parts by mass of a colloidal silica (ST-XS manufactured by Nissan Chemical Industries, Ltd) was added to 80 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 3 to 25 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof (the total amount of the silane-coupling agent (y-glycidoxypropyltrimethoxysilane) was 7.1 to 29.1 parts by mass), and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 15.5 to 18.8 % by mass), and stirred at room temperature, to give a surface-treating composition. [0079] Resin-coated metal plates 27 to 3 6 were prepared in a similar manner to Example 1, and the properties thereof were evaluated. Results are summarized in Table 3. As shown in the following Table 3, the resin-coated metal plates 27 to 33 satisfying the requirements in the amount of the silane-coupling agent specified in the present invention were superior in corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness. [0081] Example 4 Twenty parts by mass of two kinds of colloidal silicas different in surface area-average particle size ("Snowtex series" products, manufactured by Nissan Chemical Industries, Ltd) were added to 80 parts by mass of the resin composition of resin composition 1, to give a mixture (100 parts by mass in total). In addition, 10 parts by mass of a silane-coupling agent ("KBM403", manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.5 % by mass), and stirred at room temperature, to give a surface-treating composition. [0082] Resin-coated metal plates 37 to 40 were prepared in a similar manner to Example 1, and the properties were evaluated. Results are s-ummarized in Table 4. As shown in the following Table 4, the resin-coated metal plates 37 and 38 containing a colloidal silica having a favorable average particle size were superior in favorable corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness. [0083] [0084] Example 5 Twenty parts by mass of a colloidal silica {"ST-XS" manufactured by Nissan Chemical Industries, Ltd) was added • to 8 0 parts by mass of the resin component of resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7.5 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof; a dilute acjueous solution of a vanadium compound was added thereto, in an amount of 0.5 to 6 parts by mass as V2O5; and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.2 to 17.0 % by mass), and stirred at room temperature, to give a surface-treating composition. The dilute aqueous vanadium compound solution is a solution prepared by diluting "Vanadic acid solution (IV)" manufactured by Shinko Chemical Co., Ltd. to a particular concentration with pure water and adjusting its pH to 6.5 with ammonia water. [0085] Resin-coated metal plates 41 to 51 were prepared in a manner similar to Example 1 and the properties thereof were evaluated. Results are siuranarized in Table 5. As shown in the following Table 5, the resin-coated metal plates 41 to 48 containing the vanadium compound in a suitable amount were particularly superior in corrosion resistance (crosscut corrosion resistance) in the damaged Twenty parts by mass of a colloidal silica ("ST-XS" manufactured by Nissan Chemical Industries, Ltd) was added to 80 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 10 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.5 % by mass), and stirred at room temperature, to give a surface-treating composition. [008 8] Resin-coated metal plates 52 to 52 having a resin film amount in the range of 0.1 to 3.5 g/m2 were prepared by using an alkaline-degreased hot-dip zinc-coated steel sheet (Zn deposition 45 g/m2) as a metal plate and by applying the surface-treating composition by bar coating (No.3 bar) on the surface of the steel plate and heating and drying the film at a plate temperature of 90°C for approximately 12 seconds. [008 9] The properties of the resin-coated metal plates obtained were evaluated. The results are sxommarized in Table 6. As shown in the following Table 6, the resin-coated metal plates 52 to 59 having a resin film at a favorable resin coating amount were superior in corrosion resistance, coated film adhesiveness, alkali resistance and [0091] Example 7 Thirty parts by mass of a colloidal silica ("ST-XS" manufactured by Nissan Chemical Industries, Ltd) was added to 70 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7 parts by mass of a silane-coupling agent ("KBM403' manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and sodiiHn metavanadate (manufactured by Shinko Chemical Co., Ltd) was added in an amount of 2 parts by mass as Vz O5 as a vanaditim compound. In addition, 0 to 15 parts by mass of a styrene/acrylic main chain oxazoline polymer ("Epocros K- 2030E" manufactured by Nippon Shokubai Co., Ltd) was added to the 100 parts by mass of the total of the mixture above as oxazoline-containing polymer (crosslinking agent), and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter concentration of 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition. Resin-coated metal plates 63 to 16 were prepared in a similar manner to Example 1 and the properties thereof were evaluated. Results are summarized in Table 7. As shown as metal plates 63 to 72 in the following Table 6, addition of an oxazoline-containing polymer results in improvement in corrosion resistance, adhesiveness, and roll moldability. [00 93] Example 8 Thirty parts by mass of a colloidal silica ("ST-XS", manufactured by Nissan Chemical Industries, Ltd) was added to 70 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7 parts by mass of a silane-coupling agent ("KBM4 03" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and sodium metavanadate (manufactured by Shinko Chemical Co., Ltd) was added in an amount of 2 parts by mass as V2 O5 as a vanadium compound. In addition, 4 parts by mass of a styrene/acrylic main chain oxazoline polymer ("Epocros K-2030E", manufactured by Nippon Shokubai Co., Ltd) was added to the total 100 parts by mass thereof as oxazoline-containing polymer (crosslinking agent), and further, 0.5 to 5 parts by mass of spherical polyethylene wax particles having an average particle size of 0.3 pm ("Permaline KUE-17" manufactured by Sanyo Chemical Industries, Ltd) and spherical polyethylene wax particles having an average particle size of 0.6 to 7 ym ("Chemipearl W900", "Chemipearl W700", "Chemipearl W500", "Chemipearl W300", "Chemipearl W400", "Chemipearl W200" or "Chemipearl W800" manufactured by Mitsui Chemicals, Inc.) were added to the 100 parts by mass thereof; and the mixture was diluted with water for adjustment of the solid matter content (solid matter concentration 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition. Resin-coated metal plates 77 to 94 were prepared in a similar manner to Example 1 and the properties thereof were evaluated. Results are summarized in Table 8. As shown as metal plates 77 to 81 and 85 to 90 in the following Table, addition of an oxazoline-containing polymer and a spherical polyethylene wax resulted in significant improvement, in particular, in roll moldability. [0095] Example 9 Thirty parts by mass of a colloidal silica ("ST-XS", manufactured by Nissan Chemical Industries, Ltd) was added to 70 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and sodium metavanadate (manufactured by Shinko Chemical Co., Ltd) was added in an amount of 2 parts by mass as V2O5 as a vanadium compound. In addition, 4 parts by mass of a styrene/acrylic main chain oxazoline polymer ("Epocros K-2030E", manufactured by Nippon Shokubai Co., Ltd) was added to the total 100 parts by mass thereof as oxazoline-containing polymer (crosslinking agent); 2 parts by mass of spherical polyethylene wax particles having an average. particle size of 1.0 ]im ("Chemipearl W7D0" manufactured by Mitsui Chemicals, Inc.) were added to the 100 parts by mass thereof; and the mixture was diluted with water for adjustment of the solid matter content (solid matter concentration 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition- Resin-coated metal plates 95 to 109 having a resin film coating amount in the range of 0.1 to 3.5 g/m2 were prepared by using an alkaline-degreased hot-dip zinc-coated steel sheet (Zn deposition: 45 g/m2) or an alloyed hot-dip zinc-coated steel sheet (Zn deposition: 45 g/m2) or an electrolytic zinc-coated steel sheet (Zn deposition: 20 g/m2) as a metal plate, and by applying the surface-treating composition above by bar coating (No.3 bar) on the surface of the metal plate and heating and drying the resulting film at a plate temperature of 90°C for approximately 12 seconds. The properties of the resin-coated metal plates obtained were evaluated. The results are summarized in Table 9. As shown in the following Table 9, resin-coated metal plates 95 to 102 (hot-dip zinc-coated steel sheet) and those 103 to 104 (alloyed hot-dip zinc-coated steel sheet), and those 105 to 106 (electrolytic zinc-coated steel sheet) each having a resin film with a favorable resin-coating amount were all superior in corrosion resistance, coated film adhesiveness, alkali resistance, resin film adhesiveness and roll moldability. CLAIMES 1. A resin-coated metal plate having a resin film obtained with a surface-treating composition, the surface-treating composition comprising: an olefin-α β-unsaturated carboxylic acid copolymer and an α β-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass; and colloidal silica in an amount of 5 to 45 parts by mass {with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β unsaturated carboxylic acid polymer and the colloidal silica); and additionally a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica, a content ratio of the olefin-α β-unsaturated carboxylic acid copolymer to the α β-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass. 2. The resin-coated metal plate according to Claim 1, wherein the α β-unsaturated carboxylic acid polymer is polymaleic acid. 3. The resin-coated metal plate according to Claim 1 or 2, wherein the surface area-average particle size of the colloidal silica is 4 to 20 nm. 4. The resin-coated metal plate according to Claim 1 or 2, wherein the silane-coupling agent is a glycidyl group-containing silane-coupling agent. 5. The resin-coated metal plate according to Claim 1 or 2, wherein the surface-treating composition further comprising a vanadium compound in an amount of 0.5 to 6 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica. 6. The resin-coated metal plate according to Claim 1 or 2, wherein the surface-treating composition further comprising a carbodiimide group-containing compound in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer and the α β-unsaturated carboxylic acid polymer. 7. The resin-coated metal plate according to Claim 1 or 2, wherein the amount of the resin film coated is 0.2 to 3 g/m2 as dry mass, 8. A surface-treating composition, comprising: an clefin-α β-unsaturated carboxylic acid copolymer and an α β-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass;, and colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β unsaturated carboxylic acid polymer and the colloidal silica); and additionally, a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica, a content ratio of the olefin-α β-unsaturated carboxylic acid copolymer to the α β-unsaturated carboxylic acid polymer is 1,000: 1 to 10: 1 by mass. 9. The surface-treating composition according to Claim 8, further comprising a vanadium compound in an amount of 0.5 to 6 parts by mass with respect to 100 parts by mass of the total of olefin-α ,β-unsaturated carboxylic acid copolymer, the α, β-unsaturated carboxylic acid polymer and the colloidal silica. 10. The resin-coated metal plate according to Claim 1 or 2, wherein surface-treating composition further comprising an oxazoline-containing polymer in an amount of 1 to 9 parts by mass with respect to 100 parts by mass of the total of the olefin-aα β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica. 11. The resin-coated metal plate according to Claim 10, wherein the surface-treating composition further comprising spherical polyethylene wax particles having an average particle size of 0.6 to 4 um in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the total of the clefin-α β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica.

Full Text

DESCRIPTION
Resin coated metal plate and a surface-treating composition
for producing the same
Technical Field
[0001] The present invention relates to a resin-coated metal plate having a coated resin film for use, for example in automobiles, electronics appliances, building materials, and others and a surface-treating composition for production thereof, and, in particular, to a resin-coated metal plate superior in corrosion resistance, adhesiveness between the resin film and the other coated film (may be referred to as "coated film adhesiveness"), and adhesiveness between the resin film and the metal plate
(may be referred to as "resin film adhesiveness") and a surface-treating composition for production thereof.
Background Art
[0002] Zinc-coated plating steel sheets such as electrolytic zinc-coated steel sheet and hot-dip zinc-coated steel sheet and inorganic surface-finished steel plates such as zinc-coated steel sheets additionally treated with chromate for further improvement in corrosion resistance have been used as materials for use in

automobiles and the like. However, the demand for steel plates without chromate treatment is expanding because of recent increasing concern about environment. [0003] Patent Document 1 proposes a metal surface-treating agent containing an emulsion of a copolymer of a, |3-ethylenic unsaturated carboxylic acid and olefin and a crosslinking agent, as a means of replacing the chromate treatment for improvement in corrosion resistance. Alternatively, Patent Document 2 proposes surface-treating agent containing a carboxyl group-containing resin and an inorganic silicate and a surface-finished steel plate obtained by using the same.
Patent Document 1: Japanese Unexamined Patent Publication No. 2005-220,237
Patent Document 2; Japanese Unexamined Patent Publication No. 2000-282,254
Disclosure of Invention Technical Problems to be Solved
[0004] However, there is recently a demand for a resin-coated steel plate having higher corrosion resistance without chromate treatment, and thus, there is a consistent need for a means of improving the corrosion resistance in the field of the resin-coated metal plate. Accordingly, an object of the present invention is to provide a resin-

coated metal plate superior in corrosion resistance.
Means to Solve the Problems
[0005] The resin-coated metal plate according to the present invention, which achieves the object above, is a resin-coated metal plate having a resin film obtained with a surface-treating composition,
the surface-treating composition comprising:
an olefin-a,^-unsaturated carboxylic acid copolymer and an a, fJ-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass; and
colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the olef in-a, p.-unsaturated carboxylic acid copolymer, the a, p-unsaturated carboxylic acid polymer and the colloidal silica); and additionally
a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the a, jj-unsaturated carboxylic acid polymer and the colloidal silica,
a content ratio of the olefin-a,^-unsaturated carboxylic acid copolymer to the a., p-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass. [0006] Preferably in the resin-coated metal plate

according to the present invention, (1) the a,p-unsaturated carboxylic acid polymer is polymaleic acid; (2) the surface area-average particle size of the colloidal silica is 4 to 20 nm; and/or (3) the silane-coupling agent is a glycidyl group-containing silane-coupling agent.
[0007] In a favorable embodiment of the invention, the surface-treating composition further comprises (a) a vanadium compound in an amount of 0.5 to 6 parts by mass with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the a,p-unsaturated carboxylic acid polymer and the colloidal silica, and/or (b> a carbodiimide group-containing compound in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of the total of the olef in-a, (3-unsaturated carboxylic acid copolymer and the a,p-unsaturated carboxylic acid polymer. Favorably in the resin-coated metal plate according to the present invention, the amount of the resin film coated is 0.2 to 3 g/m2 as dry mass. [0008] The present invention also provides a surface-treating composition, comprising: an olef in-a, (3-unsaturated carboxylic acid copolymer and an a,^-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass;, and colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the olef in-a, p-unsaturated carboxylic acid copolymer, the a, (5-

unsaturated carboxylic acid polymer and the colloidal silica); and additionally, a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-a,^-unsaturated carboxylic acid copolymer, the a, (^-unsaturated carboxylic acid polymer and the colloidal silicar a content ratio of the olefin-a,0-unsaturated carboxylic acid copolymer to the a,p-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass. The surface-treating composition may contain additionally a vanadium compound in an amount of 0.5 to 6 parts by mass, and/or an oxazoline-containing polymer in an amount of 1 to 9 parts by mass, and/or spherical polyethylene wax particles having an average particle size of 0.6 to 4 ^m in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the total of the olefin-a,^-unsaturated carboxylic acid copolymer, the ex, p-unsaturated carboxylic acid polymer and the colloidal silica.
Effect of Invention
[0009] Surprisingly, combined use of an olefin-a,p-
unsaturated carboxylic acid copolymer and an a, {5-
unsaturated carboxylic acid polymer resulted in drastic
improvement in corrosion resistance of resin-coated metal
plate.

Best Mode for Carrying Out the Invention
[0010] An aspect of the present invention.is a surface-treating composition, comprising combination of an olefin-a,p-unsaturated carboxylic acid copolymer (hereinafter, may be referred to as "olefin-acid copolymer") and a a,p-unsaturated carboxylic acid polymer (hereinafter, may be referred to as "carboxylic acid polymer"). As shown in the Examples below, the resin-coated metal plate obtained by applying and drying a surface-treating composition containing both of them on a metal plate is significantly improved in corrosion resistance in comparison with a resin-coated metal plate obtained with a surface-treating composition containing only one of them. [ODll] In the invention, the "olefin-a,p-unsaturated carboxylic acid copolymer" or the "olefin-acid copolymer" is copolymer of an olefin and an a, ^-unsaturated carboxylic acid, and the content of the olefin-derived constituent unit is 50 % by mass or more (i.e., the content of the a,(5-unsaturated carboxylic acid-derived constituent unit is 50 % by mass or less) in the copolymer; and the "a,(S-unsaturated carboxylic acid polymer" or the "carboxylic acid polymer" is a polymer obtained from a monomer a,p-unsaturated carboxylic acid, and the content of the oc, p-unsaturated carboxylic acid-derived constituent unit in the

polymer is 90 % by mass or more. In the Examples below, an "ethylene-acrylic acid copolymer" was used as "olefin-acid copolymer", and "polymaleic acid" or "polyacrylic acid" was used as "carboxylic acid polymer".
[0012] Although the accurate mechanism for the fact that the corrosion resistance of a resin-coated metal plate is improved by surface treatment with a composition containing both an olefin-acid copolymer and a carboxylic acid polymer is yet to be understood, it seems that a dense resin film that effectively inhibits permeation of water and oxygen is formed by combined use of these resins. However, the present invention is not restricted by the reasoning. [0013] The olefin-acid copolymer for use in the present invention can be prepared by copolymerization of an olefin and an a,^-unsaturated carboxylic acid by a known method, and it is also commercially available. One or more olefin-acid copolymers may be used in the invention. [0014] The olefin for use in production of the olefin-acid copolymer is not particularly limited, but preferably ethylene, propylene, or the like, and more preferably ethylene. Either an olefin-acid copolymer containing a ,single olefin constituent unit or that containing two or more olefin constituent units may be used as olefin-acid copolymer. [0015] The a, |5-unsaturated carboxylic acid for use in

production of the oiefin-acid copolymer is also not particularly limited, but examples thereof include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and the like. Among the acids above, acrylic acid is preferable. Either an clefin-acid copolymer containing only one a,p-unsaturated carboxylic acid constituent unit or that containing two or more a,p-unsaturated carboxylic acid constituent units may be used as olefin-acid copolymer. [0016] The olefin-acid copolymer for use in the present invention may contain an other iivonomer-derived constituent unit in such a range as does not impair the advantageous effects of the present invention, i.e., corrosion resistance and others. The content of the other monomer-derived constituent unit in the olefin-acid copolymer is preferably 10 % by mass or less, more preferably 5 % by mass or less, and the most favorable olefin-acid copolymer is prepared only with an olefin and an a,^"Unsaturated carboxylic acid. A favorable olefin-acid copolymer is, for example, an ethylene-acrylic acid copolymer. [0017] The a,p-unsaturated carboxylic acid constituent unit in the olefin-acid copolymer is used for improving adhesiveness between the resin film and the metal plate and securing the amount of carboxyl groups for crosslinking

reaction. The content of the a,p-unsaturated carboxylic acid constituent unit in the copolymer is preferably 5 % by mass or more, more preferably 10 % by mass or more. However, an excessive content of the a,p-unsaturated carboxylic acid unit may lead to deterioration in corrosion resistance and alkali resistance, and thus, the constituent unit content is preferably 30 % by mass or less, more preferably 25 % by mass or less.
[0018] The weight-average molecular weight of the olefin-acid copolymer for use in the present invention is preferably 1,000 to 100,000, more preferably 3,000 to 70,000, and still more preferably 5,000 to 30,000. The weight-average molecular weight can be determined by GPC by using styrene as standard.
[0019] A homopolymer, a copolymer of one or more a,p-unsaturated carboxylic acids, or a copolymer containing another additional monomer may be used as carboxylic acid polymer. The carboxylic acid polymer can be prepared by a
known method and is also commercially available. In the present invention, one or more carboxylic acid polymers may be used.
[0020] The a,p-unsaturated carboxylic acid for use in production of the carboxylic acid polymer is not particularly limited, and examples thereof include monocarboxylic acids such as acrylic acid, methacrylic acid.

crotonic acid, and isocrotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and the like. Among them, acrylic acid and maleic acid are preferable, and maleic acid is more preferable. [0021] The carboxylic acid polymer may contain a constituent unit derived from a monomer other than a,^-unsaturated carboxylic acids above, but the content of the other monomer-derived constituent unit in the polymer is 10 % by mass or less, preferably 5 % by mass or less, and the polymer is preferably a carboxylic acid polymer constituted only by an a, (5-unsaturated carboxylic acid. Favorable examples of the carboxylic acid polymers include polyacrylic acid, polymethacrylic acid, acrylic acid-malic acid copolymers, polymaleic acid, and the like, and among them polymaleic acid is more preferable from the viewpoints of coated film adhesiveness, resin film adhesiveness and corrosion resistance. Although, the accurate mechanism for the improvement in corrosion resistance by use of the polymaleic acid is not clear, it seems that presence of carboxyl groups in a greater amount leads to improvement in adhesiveness between the resin film and the metal plate and also in corrosion resistance. However, the present invention is not restricted by the reasoning. [0 022] The weight-average molecular weight of the carboxylic acid polymer for use in the present invention is

preferably 500 to 30,000, more preferably 800 to 10,000, still more preferably 900 to 3,000, and most preferably 1,000 to 2,000. The weight-average molecular weight can be determined by GPC, by using styrene as standard. [0023] The content ratio of the olefin-acid copolymer to the carboxylic acid polymer in the surface-treating composition is 1,000: 1 to 10: 1, preferably 200: 1 to 20: 1, and more preferably 100: 1 to 100: 3. An excessively smaller content ratio of the carboxylic acid polymer may lead to restriction of the advantageous effects of using the olefin-acid copolymer and the carboxylic acid polymer in combination, while an excessively large content ratio of the carboxylic acid polymer may lead to phase separation between the olefin-acid copolymer and the carboxylic acid polymer in the surface-treating composition, possibly prohibiting production of a uniform resin film and causing deterioration in alkali resistance.
[0024] It is one of characteristics that the surface-treating composition according to the present invention contains colloidal silica. Presence of the colloidal silica in the resin film prevents erosion of the metal plate under corrosive environment by elution of silica and improves the corrosion resistance of the metal plate. [0025] Colloidal silicas are coitimercially available, and any common commercial product may be used. Examples of the

colloidal silica products include Snowtex series products such as "ST-40", "ST-XS", "ST-N", "ST-SS", and "ST-0" manufactured by Nissan Chemical Industries, Ltd., and the like. When the surface-treating composition used in forming the resin film is an aqueous composition, the kind of the colloidal silica is preferably selected properly according to the pH of the surface-treating composition, for favorable dispersion of the colloidal silica. [002 6] In the surface-treating composition, the total amount of the olefin-acid copolymer and the carboxylic acid polymer (hereinafter, may be referred to as "resin component") is 55 to 95 parts by mass, and the amount of the colloidal silica is 5 to 45 parts by mass (with respect to the 100 parts by mass of the total of the resin component and the colloidal silica). The amounts of the resin component and the colloidal silica specified in the present invention are values as solid m.atter. [0027] A colloidal silica amount of more than 45 parts by mass leads to decrease in resin component and thus to deterioration of film-forming properties of the surface-treating composition, resulting in cracking of the resin film and deterioration in corrosion resistance and other properties. The amount of the colloidal silica is preferably 30 parts by mass or less, and more preferably 25 parts by mass or less from the viewpoint of spot welding

property (wherein, the total of the resin component and the colloidal silica is 100 parts by mass). A colloidal silica amount of 25 parts by mass or less prevents accumulation of silica on the electrode during spot welding effectively. [0028] On the other hand, a colloidal silica amount of less than 5 parts by mass leads to insufficient effect of improving corrosion resistance of colloidal silica and also to deterioration in alkali resistance. The amount of the colloidal silica is preferably 10 parts by mass or more, more preferably 15 parts by mass or more {with respect to 100 parts by mass of the total of the resin component and the colloidal silica).
[0029] When excessively larger in size, the colloidal silica for use in the present invention leads to deterioration in film-forming properties of the surface-treating composition, insufficient silica elution under corrosive enviroimient, and insufficient improvement of corrosion resistance. It also leads to deterioration in alkali resistance and resin film adhesiveness. On the other hand, when the colloidal silica is too small in size, the improvement in corrosion resistance is saturated, and the silica becomes too active, causing gelation of the surface-treating composition and prohibiting production of a favorable resin film. Thus, the surface area-average particle size of the colloidal silica is preferably 4 to 20

nm. The "surface area-average particle size of silica" may be determined by the Shears method when the average particle size is about 1 to 10 nm and by the BET method when it is about 10 to 100 nm.
[0030] It is also one of characteristics of the present invention, the surface-treating composition according to the present invention contains a silane-coupling agent. Use of a silane-coupling agent improves adhesiveness between the metal and the resin film and also corrosion resistance. Thus, there is no need for addition of an acidic compound for etching the surface of the metal plate to the surface-treating composition {e.g., phosphoric acid compound, nitric acid compound or fluorine compound). It is because it is possible to improve the resin film adhesiveness with the silane-coupling agent even when the metal plate surface is not etched. A surface-treating composition for etching containing no acidic compound is improved in stability and gives a favorable resin film. [0031] The content of the silane-coupling agent in the surface-treating composition is 7 parts or more, preferably 9 parts or more, more preferably 11 parts by mass or more, and 30 parts or less, preferably 25 part or less by mass, with respect to 100 parts by mass of the total of the olefin-acid copolymer, the carboxylic acid polymer and the colloidal silica. A silane-coupling agent content of less

than 7 parts by mass leads to deterioration in resin film adhesiveness and corrosion resistance, while that of more than 30 parts by mass/ to deterioration in stability of the surface-treating composition and thus, to deterioration in adhesiveness and corrosion resistance. [0032] The silane-coupling agents are commercially available, and a common commercial product may be used in . the invention. A single or plural silane-coupling agents may be used. Examples of the silane-coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(p-methoxyethoxy)silane, y-
chloropropylmethoxysilane, Y~aminopropyl triethoxysilane, N-(p-aminoethyl)-Y-aminopropyltrimethoxysilane, N-(p-aminoethyl)-Y-aminopropylmethyldimethoxysilane, y-methacryloxypropyltrimethoxysilane, y-mercaptopropyltrimethoxysilane, and the like. [0033] Among the silane-coupling agents above, preferable are glycidyl group-containing silane-coupling agents. Such a glycidyl group-containing silane-coupling agent is highly reactive and thus is effective in improving corrosion resistance and alkali resistance. Examples of the glycidyl group-containing silane-coupling agents include ygiycidoxypropyltrimethoxysilane, y-glycidoxytnethyldimethoxysilane, and the like. [0034] The surface-treating composition according to the

present invention may contain a vanadium compound. The vanadium compound also prohibits erosion of the metal plate and improves corrosion resistance thereof, by elution thereof similarly to colloidal silica. The vanadium compound improves the corrosion resistance of steel sheet, and in particular the corrosion resistance in the damage area, especially when the metal plate is a hot-dip zinc-coated steel sheet or an electrolytic zinc-coated steel sheet.
[0035] Examples of the vanadium compounds include vanadium pentoxide (V2O5) / ammonium metavanadate {NH4VO3) , sodium metavanadate (NaVOa) 1 potassium metavanadate (KVO3) , vanadium acetylacetonate (V (CsHiOz) 3) / and the like, and these compounds may be used alone or in combination of two or more. These vanadium compounds are commercially available and thus, easily available,
[003 6] When the surface-treating composition according to the present invention is an aqueous composition, "Vanadic Acid Solution (IV)" highly soluble in water (aqueous solution containing VaOs reduced to tetravalent with oxalic acid) manufactured by Shinko Chemical Co., Ltd is preferably used as a vanadium compound. When the aqueous surface-treating composition is neutral or alkaline, the vanadic acid solution is preferably neutralized to pH 5 to 7 with a base {preferably with ammonia water) before use

(the pH of commercially available "Vanadic Acid Solution (IV)" is approximately 3). However, the vanadic acid solution, when the pH thereof is more than 7, may generate fine suspended matter of vanadium hydroxide. [0037] The content of vanadium compound in the surface-treating composition is preferably 0.5 to 6 parts by mass, more preferably 1 to 3 parts by mass, with respect to 100 parts by mass of the total of the olefin-acid copolymer, the carboxylic acid polymer and the colloidal silica. A vanadium compound content of less than 0.5 part by mass results in insufficient improvement of corrosion resistance. On the other hand, a content of more than 6 parts by mass leads to saturation of the improvement in corrosion resistance and yet to deterioration in coated film adhesiveness and resin film adhesiveness. When the "Vanadic Acid Solution" is used, the vanadium compound content specified in the present invention is the V2O5 amount calculated from the V2O5 concentration in "Vanadic Acid Solution" (provided form the manufacturer). [003 8] The surface-treating composition according to the present invention may contain a carbodiimide group-containing compound additionally. The carbodiimide group in the compound reacts with the carboxyl group in the olefin-acid copolymer and carboxylic acid polymer. Thus, it is possible to reduce the amount of carboxyl groups in

the resin film and improve alkali resistance by using such a carbodiimide group-containing compound. A single or plural carbodiimide group-containing compounds may be used in the invention.
[0039] The carbodiimide group-containing compound is prepared, for example, by heating an isocyanate, such as hexamethylene diisocyanate {HDD, xylylene diisocyanate {XDI), hydrogenated xylylene diisocyanate (HXDI), 4,4-diphenylmethane diisocyanate (MDI) or tolylene diisocyanate (TDI), in the presence of a carbodiimidation catalyst, and may be made more hydrophilic (water-soluble, water-emulsifiable or water-dispersible) by modification. When the surface-treating composition is an aqueous composition, an aqueous carbodiimide group-containing compound is preferable. A compound having plural carbodiimide groups in the molecule is also preferable. Presence of plural carbodiimide groups in the molecule improves corrosion resistance further by crosslinking reaction with the carboxyl groups in the resin component. [0040] Examples of the commercially available polycarbodiimide compounds include N,N-
dicyclohexylcarbodiimide, N,N-diisopropylcarbodiimide and "polycarbodiimides" manufactured by Nisshinbo Industries, Inc. (a polymer having plural carbodiimide groups in the molecule), and, among them, "polycarbodiimides" containing

plural carboxyi groups is preferable.
[0041] For sufficient expression of the advantageous effects of the carbodiimide group-containing compound, the content of the compound in the surface-treating composition is preferably 0.1 part by mass or laore, more preferably 0.5 part by mass or more, and more preferably 8 parts by mass or more, with respect to 100 parts by mass of the olefin-acid copolymer and carboxylic acid polymer. On the other hand, an excessive content of the carbodiimide group-containing compound leads to decrease of the combined effects of the olefin-acid copolymer and the carboxylic acid polymer. Alternatively, use of an aqueous carbodiimide group-containing componnd in an excessive amount in the aqueous surface-treating composition may give adverse effects on water resistance and corrosion resistance. From the viewpoint above, the content of the carbodiimide group-containing compound is preferably 30 parts by mass or less, more preferably 20 parts or less, and still more preferably 16 part by mass or less, with respect to 100 parts by mass of the substances above. [0042] The surface-treating composition according to the present invention may contain a resin and/or a wax other than the olefin-acid copolymer and carboxylic acid polymer in an amount in the range that does not impair the advantageous effects of the present invention. The total

amount of the other resin and wax in the surface-treating composition is preferably 10 parts by mass or lesSr more preferably 5 parts by mass or less, with respect to 100 parts by mass of the olefin-acid copolymer and carboxylic acid polymer. The surface-treating composition may contain other compounds such as crosslinking agent, diluent, skinning inhibitor, surfactant, emulsifier, dispersant, leveling agent, antifoam, penetrant, filming aid, dye, pigment, thickener and lubricant in such a range as does not impair the advantageous effects of the present invention. The surface-treating composition according to the present invention may additionally contain an oxazoline-containing polymer in an amount of 1 to 9 parts by mass with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the o(, p-unsaturated carboxylic acid polymer and the colloidal silica. The oxazoline-containing polymer allows low-temperature drying, gives a surface-treating composition resistance to deterioration in flowability (viscosity) and wettability and also superior in mechanical stability. Use of an oxazoline-containing polymer, which has a styrene/acrylic polymer main chain, gives a very hard film that is favorably adhesive to the base material and the post-coating film (favorable in resin film adhesiveness & coated film adhesiveness). Thus, the film is more

resistant to damage, even when a resin-coated metal plate is subjected to roll molding, which leads to separation of its film more frecpaently than press molding.
Examples of the oxazoline-containing polymers include "Epocros K series" products manufactured by Nippon Shokubai Co., Ltd., i.e., styrene/acrylic emulsions, such as "K-2010E", "K-2020E", and "K-2030E", and the like.
When the content of the oxazoline-containing polymer is 1 part by mass or less with respect to 100 parts by mass of the total of the olefin-a,p-unsaturated carboxylic acid copolymer, the a,^-unsaturated carboxylic acid polymer and the colloidal silica, there is no improvement in the hardness of the film, and the film is pressurized and broken by contact with the roll during roil molding, resulting in stripping of the film. When the content of the oxazoline-containing polymer is not less than 9 parts by mass with respect to 100 parts by mass of the total of the olef in-a, (3-unsaturated carboxylic acid copolymer, the a,p-unsaturated carboxylic acid polymer and the colloidal silica, there is no further improvement of the film, and the coated film adhesiveness is deteriorated significantly. The content is preferably 2 to 6 parts by mass, more preferably 3 to 4 parts by mass.
The surface-treating composition according to the present invention may contain spherical polyethylene wax

particles having an average particle size of 0.6 to 4 jjia in an amount of 0.5 to 5 parts by mass with respect to 100 parts by mass of the total of the olefin-a,^-unsaturated carboxylic acid copolymer, the a,p-unsaturated carboxylic acid polymer and the colloidal silica. It is thus possible to reduce the contact resistance between the roll and the resin-coated metal plate and prevent damaging of the film, when the resin-coated metal plate is subjected to roll molding. When used in combination with the oxazoline-containing polymer described above, it is possible to prevent the film damage further more effectively.
Examples of the spherical polyethylene wax particles include Chemipearl products (polyolefin aqueous dispersion) manufactured by Mitsui Chemicals, Inc. such as "W-100", "W-400", "W-500", "W-700", and "W-900", and the like.
Differently from during press molding, a resin-coated metal plate is molded gradually with multi-stage rolls while a coolant solution {aqueous emulsion of oil in water) is normally supplied during roll molding, and thus, there is almost no rise of the temperature of the roll or resin-coated metal plate, but it is quite important to reduce the contact resistance between the roll during molding roll and the resin-coated metal plate, by making them more lubricating to each other. It is thus necessary to disperse the spherical wax particles in the film while the

shape thereof is preserved, and thus, the temperature at which the surface-treating composition is dried after application (film-forming temperature) should not be higher than the softening point of the spherical polyethylene wax particles.
When the average particle size of the spherical polyethylene wax is not larger than 0.6 ]iJD.f there is no protrusion of film-coated wax particles formed on the film surface, prohibiting reduction in the contact resistance with rolls during roll molding. It is difficult to cover the wax particles having an average particle size of 4 yiti or more with the film, which may cause paint repellency during post-coating and also deterioration in the coated film adhesiveness after coating.
[0043] The surface-treating composition according to the present invention may be a solvent-based composition or an aqueous composition that can be applied on the surface of a metal plate, but an aqueous composition is preferable from the point of environment problem. The method of producing the surface-treating composition is not particularly limited, and the surface-treating composition can be prepared, for example, by mixing and stirring an organic solvent (in the case of a solvent-based composition) or water, preferably deionized water (in the case of an aqueous composition) with an olefin-acid copolymer, a

carboxylic acid polymer, colloidal silica and a silane-coupling agent, and as needed a vanadium compound, a carbodiimide group-containing compound and/or other component respectively in certain amounts. The mixture may be heated during agitating, but is preferably heated before addition of the silane-coupling agent and as needed the carbodiimide group compound, and not heated after addition thereof if possible, for prevention of gelation of the surface-treating composition in reaction of the olefin-acid copolymer and carboxylic acid polymer with the silane-coupling agent and the carbodiimide group-containing compound.
[004 4] It is preferable to emulsify the olefin-acid copolymer, the principal component of the resin, in producing an aqueous surface-treating composition. It is possible to emulsify the olefin-acid copolymer by using an emulsifier and/or by neutralizing carboxyl groups in the copolymer.- It is possible to reduce the average particle size of the aqueous emulsion of the olefin-acid copolymer and improve the filming efficiency and thus density of the resulting resin film, by using an emulsifier. [004 5] In a favorable embodiment, the carboxyl groups in the olefin-acid copolymer are neutralized for emulsification. It is because it is possible to reduce the amount of the emulsifier used or even eliminate the

emulsifier by neutralizing the carboxyl groups and to reduce or eliminate the adverse effects of the emulsifier on water resistance and corrosion resistance of resin film. In neutralizing the carboxyl groups in the olefin-acid copolymer, a base in an amount of preferably, approximately 0.5 to 0.95 equivalence, more preferably 0.6 to 0.8 equivalence, with respect to the carboxyl group is used. Insufficient neutralization leads to lower emulsification, while excessive neutralization leads to decrease in the amount of carboxyl groups reacting, for example, with the silane-coupling agent, resulting in adverse effects, for example, on corrosion resistance and increase in viscosity of the composition containing an olefin-acid copolymer. [0046] Examples of the bases for neutralization include strong bases such as hydroxides of an alkali or alkali-earth metal (such as NaOH, KOH, and Ca(0H)2, preferably NaOH); ammonia water, and primary, secondary and tertiary amines (preferably triethylamine). Use of a strong base such as NaOH leads to improvement in emulsification efficiency, but use of an excessive amount thereof may lead to deterioration in corrosion resistance of the resin film. On the other hand, amines, in particular low-boiling point amines, preferably amines having a boiling point of 100°C or lower under atmospheric pressure (e.g., triethylamine), do not cause much deterioration of corrosion resistance of

resin film, possibly because the low-boiling amine is vaporized when the resin film obtained by application of a surface-treating composition is dried. However, am.ines are less effective in improving the emulsification efficiency. It is thus preferable to use a strong base and an amine in combination, preferably NaOH and triethylamine, during neutralization and emulsification of the carboxylic acid, groups in the olefin-acid copolymer. When a strong base and an amine are used in combination, the strong base is used in an amount of preferably 0.01 to 0.3 equivalence and the amine in an amount of preferably 0.4 to 0.8 equivalence with respect to the carboxylic acid amount in the olefin-acid copolymer,
[0047] When an aqueous surface-treating composition is used, a small amount of organic solvent may be added for reduction of interfacial tension and improvement of the compatibility with the metal plate. Examples of the organic solvents for that purpose include methanol, ethanol, isopropanol, butanols, hexanol, 2-ethylhexanol, ethylene glycol ethylether, ethylene glycol butylether, diethylene glycol, propylene glycol, and the like. [004 8] The solid matter in the surface-treating composition is not particularly limited, and is adjusted according to the method of applying the surface-treating composition onto the metal plate. The content of the solid

matter in the surface-treating composition is generally, approximately 5 to 20 % by mass, preferably approximately 10 to 18 % by mass, for example when the composition is applied by a spray Ringer method (method of spraying a surface-treating composition on a metal plate and squeezing the wet surface with a roll).
[0049] The metal plate for use in the present invention is not particularly limited, and examples thereof include non-plated cold-drawn steel sheet, hot-dip zinc-coated steel sheet (GI), hot-zip alloyed zinc-coated steel sheet (GA), electrolytic zinc-coated steel sheet (EG), aluminum plate, titanium plate, and the like. Among them, zinc-coated steel sheet without chromate treatment is preferable. [0050] In the invention, the method of forming the resin film on a metal plate and the condition for it are not particularly limited, and a resin-coated metal plate may be produced by any Icnown application method of applying the surface-treating composition on one side or both surfaces of a metal plate and heating and. drying the resulting film. Examples of the methods of applying the surface-treating composition include curtain flow coater method, roll coater method, spraying method, spray Ringer method and the like, and among them, the spray Ringer method is preferable for example from the viewpoint of cost. The condition of heating and drying the composition is also not particularly

limited, and the heating and drying temperature is, for example, approximately 50 to 120°C, preferably 70 to 90°C. However, an excessively high heating drying temperature is undesirable because it leads to deterioration of the resulting resin film.
[0051] A excessively small amount of the resin film formed on the surface of the metal plate prohibits sufficient securement of corrosion resistance and others. On the other hand, an excessively large deposition amount is uneconomical, because of saturation of the properties such as corrosion resistance, and it may also lead to deterioration in resin film adhesiveness. Thus, the amount of the resin film formed on the resin-coated metal plate is preferably 0.2 to 3 g/m2, more preferably 0.7 to 2 g/m2 as dry mass.
EXAMPLES
[0052] Hereinafter, the present invention will be described more specifically with reference to Examples, but it should be understood that the present invention is not restricted by the following Examples, modifications can be made within the scope of the description above and below, and such modification are also included in the technical scope of the present invention.
[0053] (1) Method of evaluating the properties of resin-

coated metal plate
(1-1) Flat plate corrosion resistance
The period until the white rusting rate (white rust-generated area/ entire sample area XIOO) reached 5% was determined in the salt spray test according to JIS Z2371. [0054] (1-2) Crosscut corrosion resistance
For determination of the corrosion resistance of damaged area, a crosscut was formed on a sample with a cutter knife, and the period until the white rusting rate reached 10% was determined according to the salt spray specified in JIS Z2371. [0055] (1-3) Corrosion resistance by JASO cycle test
The JASO cycle test [a cycle of salt spraying (at 35°C for 2 hours)— drying (at 35°C and 30% humidity or less for 4 hours)-* moisturizing (at SCc and 95% humidity or more for 2 hours, respectively including transferring periods)] was performed for 15 cycles according to JIS K8502, and the white rusting rate was evaluated according to the following criteria:
(Evaluation criteria) @: White rusting rate: less than 5% O: White rusting rate: 5% or more and less than 10% A: White rusting rate: 10% or more and less than 20% x; White rusting rate: 20% or more [0056] (1-4) Coated film adhesiveness

An acrylic paint was applied for post coating on a sample to a layer thickness of 20 ]im by bar coating, baked at a temperature of 160°C for 20 minutes. Subsequently, the sample was immersed in boiling water for 1 hour, taken out, and left for 1 hour, and then, engraved in a checkerboard pattern having 100 squares at an interval of 1 mm with a cutter knife; and the number of the coated films remaining on the sample after the tape peel test was determined; and the coated film adhesiveness was evaluated according to the following criteria: (Evaluation criteria) ©: Coated film residual ratio: 100%
O: Coated film residual ratio: 99% or less to 90% or more A: Coated film residual ratio: 89% or less to 80% or more X: Coated film residual ratio: 79% or less [0057] (1-5) Alkali resistance
A sample was immersed in a solution containing 20 g/L of an alkaline degreasing agent (CL-N364S, manufactured by Nihon Parkerizing Co., Ltd.) at the liquid temperature kept to 60°C for two minutes, taken out, washed, and dried; and the period until the white rust rate reached 10% was determined in salt spray test according to JIS Z2371. [0058] (1-6) Resin film adhesiveness
For evaluation of the adhesiveness between the resin film and the metal plate, a filament tape {#9510,

manufactured by Sliontec Corporation) was bonded onto the surface of a sample; the composite was stored under the atmosphere of temperature of 40°C and RH of 98% for 168 hours; and the areal rate of the resin film remaining after removal of the filament tape was determined (residual ratio). The resin film adhesiveness was evaluated according to the following criteria: (Evaluation criteria) ®: Film residual ratio: 100%
O: Film residual ratio: less than 100% and 90% or more A: Film residual ratio: less than 90% and 70% or more X; Film residual ratio: less than 70%
(1-7) Roll moldability
In evaluating the roll moldability, the surface.of a resin-coated metal plate was scraped with a stainless steel
(SUS) protrusion (linear contact) in a roll moldability analyzer, and the resulting damage on the film was observed visually. The roll m.oldability analyzer has a flat plate dice and a dice having projections (both made of SUS steel), and a resin-coated metal plate is inserted into and withdrawn from the space between the dices under application of pressure. The size of the tested resin-coated metal plate was 40x300 ram; the withdrawal speed was 300 mm/min; and the applied pressure was 1960 N in the test.

@: No observable damage on film
O; Slight dam.age on film
A: Some damage on film
X; Some damage both on film and metal plate
[0059] (2) Resin composition
The resin-coated metal plate used in each Example was prepared by applying and drying a surface-treating composition on a metal plate. The surface-treating composition was prepared by preparing a composition containing an olefin-acid copolymer, a carboxylic acid polymer, and a silane-coupling agent in an amount smaller than a particular amount, and others (referred to as "resin composition" in each Example) and adding colloidal silica, the rest amount of the silane-coupling agent, and others to the resin composition. Hereinafter, the resin composition used in preparation of the surface-treating composition in each Example will be described. [0050} (2-1) Preparation of resin composition 1
To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company, acrylic acid constituent unit: 20 % by mass, weight-average molecular

weight; 20,000, melt index; 1300, acid value; 150), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W" manufactured by NOF Corporation, weight-average molecular weight: approximately 1100, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6,9 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FAB", manufactured by Harima Chemicals, Inc.), and 7 92.6 g of ion-exchange water; and the mixture was sealed and agitated vigorously at 150*0 and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.4 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones, Y" glycidoxypropyltrimethoxysilane) , 31.2 g of a carbodiimide group-containing compound ("polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc. weight-average molecular weight: 2,700, solid matter 40 % by mass), and 72.8 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 1 in an aqueous emulsion form (solid matter content: 20.3 % by mass, as determined according to JIS K6833). [0061] (2-2) Preparation of resin composition 2
To an emulsifying autoclave equipped with a stirrer, a

thermometer, and a temperature controller having an internal capacity of 1,0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W",manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 q of aqueous 4 8% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of an a-olefin-maleic anhydride copolymer wax ("Diacarna 30", manufactured by Mitsubishi Chemical Corporation), and 792.6 g of ion-exchange water; and the mixture was sealed and stirred vigorously at 150°C and a pressure of 5 atmospheres for 3 hours and cooled to 30'C. Then, 10.4 g of a silane-coupling agent {"TSL8350", manufactured by GE Toshiba Silicones), 31.2 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02" manufactured by Nisshinbo Industries, Inc., solid matter: 40 % by mass), and 72.8 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 2 in an aqueous emulsion form (solid matter content: 2 0.1 % by mass). [0062] (2-3) Preparation of resin composition 3
To an emulsifying autoclave equipped with a stirrer, a

thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer {"Primacor 59901", manufactured by Dow Chemical Company), 16.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W",manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of an aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FAS", manufactured by Harima Chemicals, Inc.), and 812.2 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and cooled to 30°C. Then, 10.7 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 32.2 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 75 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 3 in an aqueous emulsion form (solid matter content: 20.5 % by mass). [0063] (2-4) Preparation of resin composition 4
To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an

internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("AC5120" manufactured by Honeywell International Inc., acrylic acid constituent unit: 15 % by mass, weight-average molecular weight: 5,000, acid value: 120), 8.0 g of an aqueous polymaleic acid solution ("Nonpoi PMA-50W" manufactured by NOF Corporation, 50 % by mass), 34.6 g of triethylamine (0.8 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 5.4 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid
("Hartall FA3", manufactured by Harima Chemicals, Inc.), and 798.9 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.5 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 31.5 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 73.5 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 4 in an aqueous emulsion form
(solid matter content: 20.1 % by mass).
[0064] (2-5) Preparation of resin composition 5
To an emulsifying autoclave equipped with a stirrer, a

thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA-50W", manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine {0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of aqueous 4 8% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid (manufactured by Harima Chemicals, Inc. "Hartall FA3"), and 774.4 g of ion-exchange water; and the mixture was sealed and agitated rapidly at ISCC and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.5 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), and 10.5 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 5 in an aqueous emulsion form (solid matter content: 21.1 % by mass). [0065] (2-6) Preparation of resin composition 6
To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901",

manufactured by Dow Chemical Company), 8.0 g of an aqueous polymaleic acid solution ("Nonpol PMA~50W",manufactured by NOF Corporation, 50 % by mass), 35.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 5.9 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), and 788.1 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150'C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.4 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 31.2 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 72.8 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 6 in an aqueous emulsion form (solid matter content: 20.6 % by mass). [0066] (2-7) Preparation of resin composition 7
To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company ), 10.0 g of an aqueous polyacrylic acid solution ("AC-IOL", manufactured

by Nihonjunyaku Co., Ltd., weight-average molecular weight: 25,000, 40 % by mass), 33.5 g of triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FA3", manufactured by Hariitia Chemicals, Inc.)/ 6.9 g of aqueous 48% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), and 788.1 g of ion-exchange water ; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.4 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 31.2 g of a carbodiimide group-containing compound ("Polycarbodiiitiide 5V-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 72.8 g of ion-exchange water were added thereto, and the mixture was stirred for 10 minutes, to give a resin composition 7 in an aqueous emulsion form (solid matter content: 20.2 % by mass). [00 67] (2-8) Preparation of resin composition 8 (containing no carboxylic acid polymer, for comparison)
To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 35.5 g of

triethylamine (0.63 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of aqueous 4 8% NaOH solution (0.15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), 3.5 g of a tall oil fatty acid ("Hartall FA3", manufactured by Harima Chemicals, Inc.), and 788.1 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.3 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones), 30.9 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02", manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 72.1 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 8 (for comparison) in an aqueous emulsion form (solid matter content: 2 0.0 % by mass). [0068] (2-9) Preparation of resin composition 9 (containing no carboxylic acid polymer, for comparison)
To an emulsifying autoclave equipped with a stirrer, a thermometer, and a temperature controller having an internal capacity of 1.0 L, added were 200.0 g of an ethylene-acrylic acid copolymer ("Primacor 59901", manufactured by Dow Chemical Company), 35.5 g of triethylamine (0.S3 equivalence with respect to the

carboxyl group of ethylene-acrylic acid copolymer), 6.9 g of aqueous 48% NaOH solution (0,15 equivalence with respect to the carboxyl group of ethylene-acrylic acid copolymer), and 774.1 g of ion-exchange water; and the mixture was sealed and agitated rapidly at 150°C and a pressure of 5 atmospheres for 3 hours and then cooled to 30°C. Then, 10.2 g of a silane-coupling agent ("TSL8350", manufactured by GE Toshiba Silicones}/ 30.6 g of a carbodiimide group-containing compound ("Polycarbodiimide SV-02" manufactured by Nisshinbo Industries, Inc., solid matter content: 40 % by mass), and 71.4 g of ion-exchange water were added thereto; and the mixture was stirred for 10 minutes, to give a resin composition 9 (for comparison) in an aqueous emulsion form {solid matter content: 19.1 % by mass). [0069] (2-10) Resin compositions 10 to 14 (for comparison)
Resin composition 10 (for comparison): The polymaleic acid for resin composition 1 was replaced with an aqueous polyacrylic acid solution ("AC-IOS" manufacture by Nihonjunyaku Co., Ltd, weight-average molecular weight: 5,000, solid matter 40.3 % by mass).
Resin composition 11 (for comparison): The polymaleic acid for resin composition 1 was replaced with an aqueous polymaleic acid solution {"Nonpol PMA-50W", manufactured by NOF Corporation, solid matter content: 50.1 % by mass).

Resin composition 12 (for comparison): The polymaleic acid for resin composition 1 was replaced with an aqueous methylvinylether-maleic anhydride copolymer solution ("AN-119" manufactured by ISP Japan Ltd., weight-average molecular weight: 200,000, solid matter content: 15.3 % by mass) .
Resin composition 13 (for comparison): The ethylene-acrylic acid copolymer for resin composition 1 was replaced with an aqueous ethylene-acrylic acid copolymer resin emulsion ("HYTEC S-3121" manufactured by Toho Chemical Industry Co., Ltd, weight-average molecular weight: 40,000, solid matter content: 25.5 % by mass).
Resin composition 14 (for comparison): Triethylamine in resin composition 1 was replaced with an aqueous polyallylamine solution ("PAA-01" manufactured by Nitto Boseki Co., Ltd., weight-average molecular weight: 5,000, solid matter content: 15.1 % by mass). [0070] Example 1
A colloidal silica ("ST-XS" manufactured by Nissan Chemical Industries, Ltd, surface area-average particle size: 4 to 6 nm) was added to each of the resin compositions 1 to 14, in an amount of 20 parts by mass with respect to 80 parts by mass of the resin component therein, giving a mixture of 100 parts by mass in total. In addition, a silane-coupling agent ("KBM403" manufactured by

Shin-Etsu Chemical Co., Ltd, Y~
glycidoxypropyltrimethoxysilane) was added in an amount of 10 parts by mass with respect to the 100 parts by mass of the total of the mixture; the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 15 to 16.5 % by mass); and the mixture was agitated at room temperature, to give a surface-treating composition.
[0071] In the Example above, the resins in the "resin component" mean an olefin-acid copolymer and a carboxylic acid polymer in resin compositions 1 to 7, an olefin-acid copolymer in resin compositions 8 and 9, and the polymers respectively contained in the resin composition in resin compositions 10 to 14. When any one of the acidic resin compositions 10 to 12 (for comparison) is used, the surface-treating composition was prepared by using an acidic colloidal silica ("ST-0" manufactured by Nissan Chemical Industries, Ltd, surface area-average particle size: 10 to 20 nm) instead of the colloidal silica "ST-XS". 10072] Resin-coated metal plates 1 to 14 each having a resin film in an coating amount of 1.0 g/m2 were prepared by using an alkaline-degreased hot-dip zinc-coated steel sheet (Zn deposition: 45 g/m2) as a metal plate, and by applying the surface-treating composition above on the surface of the steel plate by bar coating (No.3 bar) and

drying the film under heat at a plate temperature of 90°C for approximately 12 seconds.
[0073] The properties of the resin-coated metal plates obtained were evaluated. The results are summarized in Table 1. As shown in the following Table 1, the resin-coated metal plates 1 to 7 each obtained with a surface-treating composition containing both an olefin-acid copolymer and a carboxylic acid polymer were superior in corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness.

Five to 45 parts by mass of a colloidal silica ("ST-XS", manufactured by Nissan Chemical Industries, Ltd) was added to 55 to 95 parts by mass of the resin component in the resin composition 1 above, giving a mixture of 100 parts by mass in total. Ten parts by mass of a silane-coupling agent ("KBM4 03" manufactured by Shin-Etsu Chemical Co., Ltd) was added additionally to the total 100 parts by mass thereof, and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition.
[0076] Resin-coated metal plates 15 to 26 were prepared in a similar manner to Example 1, and the properties thereof were evaluated. Results are summarized in Table 2. As shown in the following Table 2, the resin-coated metal plates 15 to 23 satisfying the requirements in the amounts of resin components and colloidal silica specified in the present invention were superior in corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness. [0077)

[007 8] Example 3
Twenty parts by mass of a colloidal silica (ST-XS manufactured by Nissan Chemical Industries, Ltd) was added to 80 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 3 to 25 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof (the total amount of the silane-coupling agent (y-glycidoxypropyltrimethoxysilane) was 7.1 to 29.1 parts by mass), and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter

content of 15.5 to 18.8 % by mass), and stirred at room temperature, to give a surface-treating composition. [0079] Resin-coated metal plates 27 to 3 6 were prepared in a similar manner to Example 1, and the properties thereof were evaluated. Results are summarized in Table 3. As shown in the following Table 3, the resin-coated metal plates 27 to 33 satisfying the requirements in the amount of the silane-coupling agent specified in the present invention were superior in corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness.

[0081] Example 4
Twenty parts by mass of two kinds of colloidal silicas different in surface area-average particle size ("Snowtex series" products, manufactured by Nissan Chemical Industries, Ltd) were added to 80 parts by mass of the resin composition of resin composition 1, to give a mixture (100 parts by mass in total). In addition, 10 parts by mass of a silane-coupling agent ("KBM403", manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.5 % by mass), and stirred at room temperature, to give a surface-treating composition. [0082] Resin-coated metal plates 37 to 40 were prepared in a similar manner to Example 1, and the properties were evaluated. Results are s-ummarized in Table 4. As shown in the following Table 4, the resin-coated metal plates 37 and 38 containing a colloidal silica having a favorable average particle size were superior in favorable corrosion resistance, coated film adhesiveness, alkali resistance and resin film adhesiveness. [0083]

[0084] Example 5
Twenty parts by mass of a colloidal silica {"ST-XS" manufactured by Nissan Chemical Industries, Ltd) was added • to 8 0 parts by mass of the resin component of resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7.5 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof; a dilute acjueous solution of a vanadium compound was added thereto, in an amount of 0.5 to 6 parts by mass as V2O5; and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.2 to 17.0 % by mass), and stirred at room temperature, to give a surface-treating composition.
The dilute aqueous vanadium compound solution is a solution prepared by diluting "Vanadic acid solution (IV)" manufactured by Shinko Chemical Co., Ltd. to a particular concentration with pure water and adjusting its pH to 6.5

with ammonia water.
[0085] Resin-coated metal plates 41 to 51 were prepared in a manner similar to Example 1 and the properties thereof were evaluated. Results are siuranarized in Table 5. As shown in the following Table 5, the resin-coated metal plates 41 to 48 containing the vanadium compound in a suitable amount were particularly superior in corrosion resistance (crosscut corrosion resistance) in the damaged

Twenty parts by mass of a colloidal silica ("ST-XS" manufactured by Nissan Chemical Industries, Ltd) was added to 80 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 10 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter content of 16.5 % by mass), and stirred at room temperature, to give a surface-treating composition.
[008 8] Resin-coated metal plates 52 to 52 having a resin film amount in the range of 0.1 to 3.5 g/m2 were prepared by using an alkaline-degreased hot-dip zinc-coated steel sheet (Zn deposition 45 g/m2) as a metal plate and by applying the surface-treating composition by bar coating
(No.3 bar) on the surface of the steel plate and heating and drying the film at a plate temperature of 90°C for approximately 12 seconds.
[008 9] The properties of the resin-coated metal plates obtained were evaluated. The results are sxommarized in Table 6. As shown in the following Table 6, the resin-coated metal plates 52 to 59 having a resin film at a favorable resin coating amount were superior in corrosion resistance, coated film adhesiveness, alkali resistance and

[0091] Example 7
Thirty parts by mass of a colloidal silica ("ST-XS" manufactured by Nissan Chemical Industries, Ltd) was added to 70 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7 parts by mass of a silane-coupling agent ("KBM403' manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and sodiiHn metavanadate (manufactured by Shinko Chemical Co., Ltd) was added in an amount of 2 parts by mass as Vz O5 as a vanaditim compound. In addition, 0 to 15 parts by mass of a styrene/acrylic main chain oxazoline polymer ("Epocros K-

2030E" manufactured by Nippon Shokubai Co., Ltd) was added to the 100 parts by mass of the total of the mixture above as oxazoline-containing polymer (crosslinking agent), and the mixture was diluted with water for adjustment of the solid matter content (to a solid matter concentration of 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition.
Resin-coated metal plates 63 to 16 were prepared in a similar manner to Example 1 and the properties thereof were evaluated. Results are summarized in Table 7. As shown as metal plates 63 to 72 in the following Table 6, addition of an oxazoline-containing polymer results in improvement in corrosion resistance, adhesiveness, and roll moldability.

[00 93] Example 8
Thirty parts by mass of a colloidal silica ("ST-XS", manufactured by Nissan Chemical Industries, Ltd) was added to 70 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7 parts by mass of a silane-coupling agent ("KBM4 03" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and sodium metavanadate (manufactured by Shinko Chemical Co., Ltd) was added in an amount of 2 parts by mass as V2 O5 as a vanadium compound. In addition, 4 parts by mass of a styrene/acrylic main chain oxazoline polymer ("Epocros K-2030E", manufactured by Nippon Shokubai Co., Ltd) was added to the total 100 parts by mass thereof as oxazoline-containing polymer (crosslinking agent), and further, 0.5 to 5 parts by mass of spherical polyethylene wax particles having an average particle size of 0.3 pm ("Permaline KUE-17" manufactured by Sanyo Chemical Industries, Ltd) and spherical polyethylene wax particles having an average particle size of 0.6 to 7 ym ("Chemipearl W900", "Chemipearl W700", "Chemipearl W500", "Chemipearl W300", "Chemipearl W400", "Chemipearl W200" or "Chemipearl W800" manufactured by Mitsui Chemicals, Inc.) were added to the 100 parts by mass thereof; and the mixture was diluted with water for adjustment of the solid matter content (solid

matter concentration 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition.
Resin-coated metal plates 77 to 94 were prepared in a similar manner to Example 1 and the properties thereof were evaluated. Results are summarized in Table 8. As shown as metal plates 77 to 81 and 85 to 90 in the following Table, addition of an oxazoline-containing polymer and a spherical polyethylene wax resulted in significant improvement, in particular, in roll moldability.

[0095] Example 9
Thirty parts by mass of a colloidal silica ("ST-XS", manufactured by Nissan Chemical Industries, Ltd) was added to 70 parts by mass of the resin component in resin composition 1, to give a mixture (100 parts by mass in total). In addition, 7 parts by mass of a silane-coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd) was added to the total 100 parts by mass thereof, and sodium metavanadate (manufactured by Shinko Chemical Co., Ltd) was added in an amount of 2 parts by mass as V2O5 as a vanadium compound. In addition, 4 parts by mass of a styrene/acrylic main chain oxazoline polymer ("Epocros K-2030E", manufactured by Nippon Shokubai Co., Ltd) was added to the total 100 parts by mass thereof as oxazoline-containing polymer (crosslinking agent); 2 parts by mass of spherical polyethylene wax particles having an average. particle size of 1.0 ]im ("Chemipearl W7D0" manufactured by Mitsui Chemicals, Inc.) were added to the 100 parts by mass thereof; and the mixture was diluted with water for adjustment of the solid matter content (solid matter concentration 16.5 % by mass) and stirred at room temperature, to give a surface-treating composition-
Resin-coated metal plates 95 to 109 having a resin film coating amount in the range of 0.1 to 3.5 g/m2 were prepared by using an alkaline-degreased hot-dip zinc-coated

steel sheet (Zn deposition: 45 g/m2) or an alloyed hot-dip zinc-coated steel sheet (Zn deposition: 45 g/m2) or an electrolytic zinc-coated steel sheet (Zn deposition: 20 g/m2) as a metal plate, and by applying the surface-treating composition above by bar coating (No.3 bar) on the surface of the metal plate and heating and drying the resulting film at a plate temperature of 90°C for approximately 12 seconds.
The properties of the resin-coated metal plates obtained were evaluated. The results are summarized in Table 9. As shown in the following Table 9, resin-coated metal plates 95 to 102 (hot-dip zinc-coated steel sheet) and those 103 to 104 (alloyed hot-dip zinc-coated steel sheet), and those 105 to 106 (electrolytic zinc-coated steel sheet) each having a resin film with a favorable resin-coating amount were all superior in corrosion resistance, coated film adhesiveness, alkali resistance, resin film adhesiveness and roll moldability.

CLAIMES
1. A resin-coated metal plate having a resin film
obtained with a surface-treating composition,
the surface-treating composition comprising: an olefin-α β-unsaturated carboxylic acid copolymer and an α β-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass; and
colloidal silica in an amount of 5 to 45 parts by mass {with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β unsaturated carboxylic acid polymer and the colloidal silica); and additionally
a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica,
a content ratio of the olefin-α β-unsaturated carboxylic acid copolymer to the α β-unsaturated carboxylic acid polymer being 1,000: 1 to 10: 1 by mass.
2. The resin-coated metal plate according to Claim 1,
wherein the α β-unsaturated carboxylic acid polymer is
polymaleic acid.

3. The resin-coated metal plate according to Claim 1 or 2, wherein the surface area-average particle size of the colloidal silica is 4 to 20 nm.
4. The resin-coated metal plate according to Claim 1 or 2, wherein the silane-coupling agent is a glycidyl group-containing silane-coupling agent.
5. The resin-coated metal plate according to Claim 1 or 2, wherein the surface-treating composition further comprising a vanadium compound in an amount of 0.5 to 6 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica.
6. The resin-coated metal plate according to Claim 1 or 2, wherein the surface-treating composition further comprising a carbodiimide group-containing compound in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer and the α β-unsaturated carboxylic acid polymer.

7. The resin-coated metal plate according to Claim 1 or 2, wherein the amount of the resin film coated is 0.2 to 3 g/m2 as dry mass,
8. A surface-treating composition, comprising:
an clefin-α β-unsaturated carboxylic acid copolymer and an α β-unsaturated carboxylic acid polymer in a total amount of 55 to 95 parts by mass;, and
colloidal silica in an amount of 5 to 45 parts by mass (with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β unsaturated carboxylic acid polymer and the colloidal silica); and additionally,
a silane-coupling agent in an amount of 7 to 30 parts by mass with respect to 100 parts by mass of the total of the olefin-α β-unsaturated carboxylic acid copolymer, the α β-unsaturated carboxylic acid polymer and the colloidal silica,
a content ratio of the olefin-α β-unsaturated carboxylic acid copolymer to the α β-unsaturated carboxylic acid polymer is 1,000: 1 to 10: 1 by mass.
9. The surface-treating composition according to
Claim 8, further comprising a vanadium compound in an
amount of 0.5 to 6 parts by mass with respect to 100 parts

by mass of the total of olefin-α ,β-unsaturated carboxylic acid copolymer, the α, β-unsaturated carboxylic acid polymer and the colloidal silica.
10. The resin-coated metal plate according to Claim 1
or 2, wherein surface-treating composition further
comprising an oxazoline-containing polymer in an amount of
1 to 9 parts by mass with respect to 100 parts by mass of
the total of the olefin-aα β-unsaturated carboxylic acid
copolymer, the α β-unsaturated carboxylic acid polymer and
the colloidal silica.
11. The resin-coated metal plate according to Claim
10, wherein the surface-treating composition further
comprising spherical polyethylene wax particles having an
average particle size of 0.6 to 4 um in an amount of 0.5 to
5 parts by mass with respect to 100 parts by mass of the
total of the clefin-α β-unsaturated carboxylic acid
copolymer, the α β-unsaturated carboxylic acid polymer and
the colloidal silica.

Documents:

4725-CHENP-2008 CORRESPONDENCE OTHERS 22-03-2013.pdf

4725-CHENP-2008 CORRESPONDENCE OTHERS 26-07-2013.pdf

4725-CHENP-2008 EXAMINATION REPORT REPLY RECEIVED 28-06-2013.pdf

4725-CHENP-2008 FORM-3 26-07-2013.pdf

4725-CHENP-2008 AMENDED PAGES OF SPECIFICATION 28-06-2013.pdf

4725-CHENP-2008 AMENDED CLAIMS 28-06-2013.pdf

4725-CHENP-2008 FORM-3 28-06-2013.pdf

4725-CHENP-2008 OTHERS 28-06-2013.pdf

4725-chenp-2008 abstract.pdf

4725-chenp-2008 claims.pdf

4725-chenp-2008 correspondence-others.pdf

4725-chenp-2008 description(complete).pdf

4725-chenp-2008 form-1.pdf

4725-chenp-2008 form-18.pdf

4725-chenp-2008 form-26.pdf

4725-chenp-2008 form-3.pdf

4725-chenp-2008 form-5.pdf

4725-chenp-2008 pct.pdf

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Patent Number

258847

Indian Patent Application Number

4725/CHENP/2008

PG Journal Number

07/2014

Publication Date

14-Feb-2014

Grant Date

11-Feb-2014

Date of Filing

05-Sep-2008

Name of Patentee

KABUSHIKI KAISHA KOBE SEIKO SHO ( KOBE STEEL, LTD.)

Applicant Address

10-26, WAKINOHAMA-CHO, 2-CHOME, CHOU-KU, KOBE-SHI, HYOGO651-8585,

Inventors:

#	Inventor's Name	Inventor's Address
1	NAKAMOTO,TADASHIGE,	C/O KAKOGAWA WORKS IN KOBE STEEL, LTD., KANAZAWA-CHO, 1, KAKOGAWA-SHI, HYOGO 675-0137,
2	IWA, TATSUHIKO,	C/O KAKOGAWA WORKS IN KOBE STEEL, LTD., KANAZAWA-CHO, 1, KAKOGAWA-SHI, HYOGO 675-0137,
3	SHINOHARA, YOSHIAKI,	C/O KAKOGAWA WORKS IN KOBE STEEL, LTD., KANAZAWA-CHO, 1, KAKOGAWA-SHI, HYOGO 675-0137,

PCT International Classification Number

C23C26/00

PCT International Application Number

PCT/JP07/54441

PCT International Filing date

2007-03-07

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2006-061179	2006-03-07	Japan