Title of Invention	A CATIONIC ELECTRODEPOSITION COATING COMPOSITIONS
Abstract	The present invention relates to a cationic electrodeposition coating composition comprising a combination of components A, B and C in amounts of 5 to 80% by wt, 5 to 80% by wt and 10 to 40% by wt respectively based on the total solid content of A, B and C wherein component A is an amino containing epoxy resin such . as herein described having an average molecular weight of 500 to 5000; component B is an amino containing acrylic resin such as herein described and component C is a known blocked polyisocyanate curing agent.

Title of Invention

A CATIONIC ELECTRODEPOSITION COATING COMPOSITIONS

Abstract

The present invention relates to a cationic electrodeposition coating composition comprising a combination of components A, B and C in amounts of 5 to 80% by wt, 5 to 80% by wt and 10 to 40% by wt respectively based on the total solid content of A, B and C wherein component A is an amino containing epoxy resin such . as herein described having an average molecular weight of 500 to 5000; component B is an amino containing acrylic resin such as herein described and component C is a known blocked polyisocyanate curing agent.

Full Text	[Detailed Description of the Invention] [Technical Field to which the Invention Belongs] The present invention relates to a cationic resin composition capable of providing a cationic electrodeposition coating having excellent weatherability and corrosion resistance, and good long-term bath stability. [Prior Art and Problems that the Invention is to Solve] Cationic electrodeposition coatings have been used for wide ranging purposes including automobile undercoating a,nd those having vaxious characteristics have been developed. As Inventions intended to satisfy both weatherabillty and corrosion resistance, those having an ©poxy resin and an acrylic resin and forming, on a steel plate side, a layer rich in. the epoxy resin superior in corrosion resistance and, on the film surface aide, the other layer rich in the acrylic resin are disclosed in Japanese Patents Laid-open Nos. 333528/1996, 292131/1998, 345394/2000 and 234116/2001, In the cationic electrodeposition coating, a film is formed by filling an electrodeposition bath of 5 to 300 m" with a cationic electrodeposition coating, applying a voltage to an automobile body or part which is to be coated, thereby depositing a film thereon, and then baking anjd drying the film. Application of a cationic electrodeposition coating requires, in addition to an electrodeposition! tank, collecting and water washing equipment, UF eq\|uipment and precise filtration equipment. The cationic electrodeposition coating receives many stresses such as mechan\|ical one upon circulation or washing of a collected liquid [with water, mechanical stress due to a pressure differencje upon passing through the filtration equipment, mechanical Istress occurring upon suction of a pump in the electrodeposltl\|on tank or delivery, and chemical stress owing to contaminatlon by a degreased liquid or chemical liquid brought in by an automobile body or volatilization of a solvent. When the amount of substances to be coated decreases, a decline in the loss of a coating occurs, leading to a decrease in the amount of the coating to be supplemented. The remaining coating inevitably receives mechanical or chemical stress as described above for a long period of time. For example, 1 turnover/month (replaced ratio: about 65%/month) means that it takes a month to add, to an electrodepositlon tank, a coating in an amount to make up for the loss by line coating. In an electrodepositlon line of 0.1 turnover/month (which line may hereinafter be called "low-speed turnover line"). It takes 10 months for 65% of a coating in an electrodepositlon tank to be replaced. The remaining 35% of the coating inevitably undergoes a stress for more than 10 months. For a cationic electrodepositlon coating, long-term stability of the coating is therefore important. Application of a conventional cationic electrodepositlon coating, which contains resins drastically different in a solubility parameter, to a low-speed turnover coating line sometimes causes problems such as deterioration in coating finish, clogging upon precise filtration, clogging upon ultrafiltration and disturbance of maintenance such as cleaning by agglomerates appearing in an electrodepositlon tank. There is accordingly a demand for the development of a cationic electrodepositlon coating excellent in long-term stability of the coating and having both weatherability and corrosion resistance. [Means for Solving the Problems] The present inventors have proceeded with an extensive investigation with a view to overcoming the above-described problems and as a result, invented a cationic electrodeposition coating excellent in stability of the coating and good in both weatherability and corrosion resistance by mixing an amino-containing epoxy resin (A); an amino-containing acrylic resin (B) available by adding an amino-containing compound to a copolymer resin available by-' radical copolymerization of a polylactone-modified hydroxyl-containing radical copolymerizable monomer, which is obtained by adding a lactone to a hydroxyl-containing acrylic monomer, and a glycidyl (meth)aerylate as essential components, and another radical copolymerizable monomer; and a blocked polyisocyanate curing agent (C). Accordingly, the present invention provides a cationic electrodeposition coating composition comprising a combination of components A, B and C in amounts of 5 to 80% by wt, 5 to 80% by wt and 10 to 40% by wt respectively based on the total solid content of A, B and C wherein component A is an amino containing epoxy resin such as herein described having an average molecular weight of 500 to 5000; component B is an amino containing acrylic resin such as herein described and component C is a known blocked polyisocyanate curing agent. [Mode for Carrying Out the Invention] The present invention relates to a cationic resin composition excellent in stability of the coating, weatherabllity and corrosion resistance. Amino-containing epoxy resin (A) : Examples of the amino-containing epoxy resin include (I) an adduct of a polyepoxy compound and a primary mono- or-poly-amine, a secondary mono- or poly-amine or a primary and secondary polyamine mixture (for example, that described in U.S. Patent No, 3.984.299); (II) an adduct of a polyepoxide compound and a secondary mono- or polyamine having a ketimine-blocked primary amino group; and (III) a reaction product available by etherification of a polyepoxide compound and a hydroxyl compound having a ketimine-blocked primary amino group (for example, that described in Japanese Patent Laid-open No. 43013/1984). As the epoxide compound to be used for the preparation of the above-described amine-added epoxy resin, suited is a compound having, in one molecule thereof, at least two epoxy groups and having usually a number-average molecular weight of at least 2000. preferably from 400 to 3,000. more preferably from 800 to 2,000, with that available by the reaction between a polyphenol compound and epichlorohydrin being particularly preferred. Examples of the polyphenol compound usable for the formation of the polyepoxide compound include bis(4-hydroxyphenyl)-2,2-propane, 4,4-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-tert-butyl-phenyl)-2,2-propane, bis(2-4-hydroxy-tert-butyl-phenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane, tetra(4-hYdroxyphenyl)-l,1,2,2-ethane. 4.4-dihydroxydiphenylsulfone, phenol novolak, cresol novolak. The polyepoxide compound partially reacted with a polyol. polyether polyol, polyester polyol, polyamidoamine, polycarboxylic acid, or polyisocyanate compound Is also usable. Alternatively, a polyepoxide compound obtained by graft polymerization with e-caprolactone or an acrylic monomer is usable. As the amino-containing epoxy resin (A), suited is that having a number-average molecular weight ranging from 500 to 5,000, especially from 600 to 4,500, more preferably from 800 to 4,000, an amine value ranging from 40 to 80 mg KOH/g, a primary hydroxyl value ranging from 10 to 200 mg KOH/g and a solubility parameter 6;, ranging from 9.5 to 11.5. The solubility parameter is a parameter as shown in the following (Note 1). (Note 1) Solubility parameter: The solubility parameter (SP value) represents a measure of an intermolecular action between liquid molecules. In the present invention, the SP value is calculated in accordance with the following equation (1): wherein, SP1, SP2, ... and SP„ represents the SP of the respective monomers, and fw1, fW2, •••, and fw„ represent weight fractions of the respective monomers based on a total weight of the monomers. The SPs of polymerizable monomers are written briefly in "J. Paint Technology, 42, 176(1970)". The monomer not listed in the above literature, reference may be made to a catalog issued by a manufacturer. The above-described amino-containing epoxy resin (A) can form a film excellent in weatherability and corrosion resistance by being added, together with an amino-containing acrylic resin (B), to a cationic electrodeposition coating. Amino-containing acrylic resin (B): The amino-containing acrylic resin (B) to be used in the present invention is prepared by obtaining a copolymer resin by the radical copolymerization of, as essential components, a polylactone-modlfied hydroxyl-containing radical copolymerizable monomer (b-1), which is obtained by adding a lactone to a hydroxyl-containing monomer (b) and is represented by the following formula (1) or (2): -tC-henfiCcal formula b]— (wherein, R^ represents H or an alkyl group, R^ represents any one of -(CHJ^-, -(CO)O-(CHj)„- and -O-(CO) - (CH2)„-. 1 stands for an integer of 3 to 10, m stands for an integer of 4 to 8 and n stands for an integer of 1 to 10), [ Chemiual foi'iiiuld 6 ] ' (wherein, Ri represents H or an alkyl group, R^ represents any one of -(CHJ^-, -(CO)0-(CHJ„- and -O-(CO) - (CHj)^-, 1 stands for an integer of 3 to 10, k stands for an integer of 0 to 4 and n stands for an integer of 1 to 10), and glycidyl (meth)aerylate (b-2), and another radical copolymerizable monomer (b-3); and then adding an amino-containing compound (b-4) to the resulting copolymer resin. Examples of the hydroxyl-containing acrylic monomer (b) include 2-hydroxyethyl (meth)aerylate, 2-hydroxypropyl (meth)aerylate, 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate. Addition of a lactone thereto can yield a polylactone-modified hydroxyl-containing radical copolymerizable monomer (b-1) represented by the formula (1) or (2). The addition products of 2-hydroxyethyl (meth)aerylate and caprolactone include, for example, "PLACCEL FA-3" and "PLACCEL PM-S" (each, trade name; proiiuct of Dalcel Chemical Industries, Ltd.). They may be used either singly or in combination. The content of the polylactone-modified hydroxyl-containing radical copolymertzable monomer (b-1) ranges from 5 to 40 wt%. preferably from 10 to 35 wt%, based on the total amount of the monomer components constituting the resin (B). Contents of the polylactone-modified hydroxyl-containing radical copolymerizable monomer (b-1) exceeding 40 wt% soften the resin (B), thereby deteriorating the corrosion resistance of the electrodeposited film. Those less them 5 wt%, on the other hand, lower the compatibility between the resin (B) and the amino-containing epoxy resin (A), thereby deteriorating the stability of the coating and also the coating finish (film appearance). In order to impart the monomer with water solubility, an active-hydrogen-containing amine compound may be added to glycidyl (meth)acrylate (b-2) or they may be subjected to ring-opening copolymerization to add the active-hydrogen-containing amine compound to the terminal of glycidyl (meth)acrylate. The content of glycidyl (m6th)acrylate (b-2) ranges from 2 to 30 wt%, preferably from 5 to 25 wt% based on the total eimount of the monomer components constituting the resin (B). When the content of glycidyl (meth)acrylate (b-2) exceeds 30 wt%, a film formed using a cationic electrodeposition coating containing the resulting resin (B) has deteriorated weatherability. Contents less than 2 wt%, on the other hand, deteriorate the water dispersibility of the resin (B). As the another radical copolymerizable monomer (b-3), hydroxyl-containing acrylic monomers (b) similar to those described above are usable. Examples include 2-hydroxy6thyl (meth)acrylate, 2-hydroxypropyl (meth)acrylatey 4-hydroxybutyl (meth)aerylate and 2-hydroxyethyl (methlacrylate. Amino-containing acrylic monomers are also usable. Examples include N,N-dimethylaininoethyl (meth)acrylate, N,N-diethylaminoethyl (me th) aery late, N,N-dimethyleiminopropyl (meth)acrYlat6, N,N-di-t-butylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylamide. In addition, usable are methyl (meth)acrylate, ethyl (meth)aerylate, n-propyl (meth)aerylate, isopropyl (meth)aerylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)aerylate,CYClohexyl (m©th)acrylate, 2-ethylhexyl (meth)acrylate, styrene, vinyl toluene and a-methylstyrene. Such a monomer (b-3) is used in an amount of from 30 to 93 parts by weight, based on the total amount of the monomer components constituting the resin (B) . Amounts less than 30 parts by weight deteriorate corrosion resistance and weatherablllty, while those exceeding 90 parts by weight deteriorate compatibility with the amino-containing resin and water dispersibility. Examples of the organic solvent to be used for radical copolymerization include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl isobutyl ketone and cyclohexanone, and alcoholic solvents such as n-butanol, ethyl cellosolve. butyl cellosolve, methoxypropanol, and diethylene glycol monobutyl ether. As the organic solvent, they may be used either singly or as a mixture of a plurality of them. The radical copolymerization reaction can usually be carried out by reacting the above-described monomer components in the above-described organic solvent maintained at from about 50°C to. SOO'C, preferably from about 60'C to 250'C for about one hour to 24 hours, preferably from about 2 hours to 10 hours under an inert gas such as nitrogen gas. Examples of the amino-containing compound (b-4) to be added to impart water dispersibility include primary mono- or polyamlnes, secondary mono- or polyamines, a mixture of primary and secondary polyamines, secondary mono- or polyamines having a ketimine-blocked primary amino group, and hydroxyl compounds having a ketimine-blocked primary amino group. More specifically, use of diethylamine, diethanolamine or ketimine-blocked diethylenetriamine is preferred. The ainino-containing acrylic resin (B) has a number-average molecular weight ranging from 1,000 to 50,000, preferably from 2,000 to 20,000. When the number-average molecular weight is less than 1,000, the emulsion has impaired stability, while when it exceeds 50,000, the smoothness on the film surface is impaired. The number-average molecular weight outside the above-described range is therefore not preferred. The amino-containing acrylic resin (B) having an amine value reunging from 10 to 125 mg KOH/g, a hydroxyl value ranging from 10 to 300 mg KOH/g and a solubility parameter 6^^ (Note 1) ranging from 9.5 to 11.5 is suited in the present invention. When an amine value exceeds 125 mg KOH/g, hydrophilic properties of the resin (B) increase, resulting in a deterioration in the performances of the electrodeposited film such as weatherability and corrosion resistance. Amine values less than 10 mg KOH/g, on the other hand, cause a drastic worsening in water dispersibility of an emulsion of the resin (A). When the hydroxyl value exceeds 300 mg KOH/g, hydrophilic properties of the resin (B) increase, resulting in a deterioration in the corrosion resistance of the electrodeposited film. The hydroxyl value less than 10 mg KOH/g, on the other hand, lowers water dispersibility and a cross-linking density, leading to a deterioration in the film performance. When the solubility parameter 6^, is less than 9.5, the compatibility with the amino-containing epoxy resin lowers. Solubility parameters exceeding 11.5, on the other hand, lead to a deterioration in weatherability. In the present invention, a difference in the SP value between the amino-containing epoxy resin (A) and the amino-containing acrylic resin (B) is preferably 0 to 0.7. The difference of the SP value exceeding 0.7 may cause a deterioration in the long-term stability of the coating, or cause a layer separation of the film containing both resins, thereby deteriorating adhesion or moisture resistance. Blocked polyisocyanate curing agent (C): The blocked polyisocyanate curing agent (C) is a product of addition reaction between a polyisocyanate compound and an isocyanate blocking agent in a stoichiometric ratio. As the polyisocyanate compound, conventional ones can be used. Examples include aromatic, aliphatic or alicyclic polyisocyanate compounds such as trylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate (usually called "MDI"), crude MDEi, bisCisocyanatomethyDcyclohexane, tetramethylen© diisocyanate, hexamethylene diisocyanate, methylene diisocyanate and isophorone diisocyanate; cyclic polymers of these polyisocyanate compounds and isocyanate-biuret; and terminal-isocyanate-containing compounds available by reacting an excess amount of such an isocyanate compound with a low-molecular active-hydrogen-containing compound such as ethylene glycol, propylene glycol, trimethylolpropane, heKanetriol or castor oil. These polyisocyanate compounds may be used either singly or in combination. The above-described isocyanate blocking agent is added to the isocyanate group of a polyisocyanate compound to block it. The blocked polyisocyanate compound prepared by the addition reaction is stable at normal temperature, but when heated at a film baking temperature (usually, about 100 to 200'C), it desirably causes dissociation of the blocking agent and regenerates the free isocyanate group. Examples of the blocking agent capable of satisfying the above requirements include lactam compounds such as s-caprolactam and Y-caprolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; aliphatic alcohols such as n-butanol and 2-ethylh.exanol; aromatic alkyl alcohols such as phenylcarbinol and meth-ylpbenylcarbinol; and ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether. As well as these blocking agents, blocked polyisocyanate crosslinking agents (II) containing, as a blocking agent, a diol containing two hydroxyl groups different in reactivity and having a molecular weight of 76 to 150 or a carboxyl-containing diol having a molecular weight of 106 to 500 may be used. [0023] The above-described diol contains two hydroxyl groups different in reactivity, for example, a primary hydroxyl group and a secondary hydroxyl group, a primary hydroxyl group and a tertiary hydroxyl group, or a secondary hydroxyl group and a tertiary hydroxyl group; and has a molecular weight of 76 to 150. Examples of the diol having two hydroxyl groups different in reactivity include propylene glycol, dipropylene glycol, 1,3-butanediol, 1,2-butanediol, 3-methyl-l,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-l,3-pentanediol, 1,5-hexanediol and 1.4-hexanediol. Of these, propylene glycol is preferred from the viewpoints of the reactivity of the blocked polyisocyanate, a reduction in heating loss, and storage stability of the resulting coating. The reaction with an isocyanate group usually starts first with the hydroxyl group having a higher reactivity, thereby blocking the isocyanate group. The above-described carboxyl-containing diol embraces a carboxyl-containing diol having a molecular weight of 106 to 500. It is able to have improved low-temperature dissociation property and in turn, improved low-temperature curing property, by having, in the molecule thereof, a carboxyl group. Particularly, use of an organotin compound as a curing catalyst brings about a drastic improvement in the low-temperature curing property. Examples of the carboxyl-containing diol include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, dimethylolvaleric acid and glyceric acid. The cationic resin composition of the cationic electrodeposition coating contains the amino-containing epoxy resin (A), amino-containing acrylic resin (B), and blocked polyisocyanate curing agent (C) and it preferably contains them in amounts of 5 to 80 wt%, 5 to 80 wt% and 10 to 40 wt%, respectively, each based on the total solid content of the resin (A), resin (B) and curing agent (C). Neutralization and dispersion of the cationic resin composition are conducted as follows. After the amino-containing epoxy resin (A), amino-containing acrylic resin (B) and blocked polyisocyanate curing agent (C) are mixed sufficiently, a dissolved varnish thus obtained is added with one or more of neutrallzers selected from formic acid, acetic acid, lactic acid, propionic acid, citric acid, malic acid and sulfamic acid. The resulting mixture is dispersed in water to yield an emulsion for a cationic electrodeposition coating. Amounts of the amino-containing epoxy resin (A) less than 5 wt% lower corrosion resistance, while those exceeding 80 wt% lower weatherability. Amounts of the amino-containing acrylic resin (B) less than 5 wt% lower weatherability, while those exceeding 80 wt% lower corrosion resistance. Amounts of the blocked polyisocyanate curing agent (C) less than 10 wt% lower the curing property, while those exceeding 40 wt% cause a deterioration in the storage stability of the coating. Addition of acetic acid and/or formic acid as the neutralizer is preferred, because it brings about excellent coating finish, throwing power of electrolytic coating, low-temperature curing property and stability of the coating. It is preferred to add, to the cationic resin composition, a bismuth compound as a rust preventive. Although no particular limitation is imposed on the bismuth compound, bismuth oxide, bismuth hydroxide, basic bismuth carbonatey bismuth nitrate and bismuth silicate can be given as examples. Of these, bismuth hydroxide is preferred. Alternatively, a bismuth salt of an (oxy)organic acid prepared by reacting the above-described bismuth compound with at least two organic acids, at least one of which is an aliphatic hydroxycarboxylic acid, may be used. Examples of the aliphatic carboxylic acid used in the preparation of the bismuth salt of an (oxy)organic acid may include glycolic acid, glyceric acid, lactic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolvaleric acid, tartaric acid, malic acid, hydroxymalonic acid, dihydroxysuccinic acid, trihydroxysuccinic acid, methylmalonic acid, benzoic acid and citric acid. The content of the bismuth compound in the cationic electrodeposition coating is not limited precisely, but can be varied widely depending on the performance that the coating is required to have. The content of.the bismuth compound is adjusted within a range of 0.01 to 10 parts by weight, preferably from 0.05 to 5 parts by weight, based on 100 parts by weight of the total solid content of the cationic resin composition of the cationic electrodeposition coating composition including the amino-containing epoxy resin (A), amino-containing acrylic resin (B) and blocked polyisocyanate curing agent (C). The cationic electrodeposition coating composition may contain, as a curing catalyst, a tin compound in addition to the above-described components. Examples of the tin compound Include organotin compounds such as dibutyltin oxide and dioctyltln oxide; and aliphatic or aromatic carboxylates of a dialkyltin such as dibutyltin dilaurate, dioctyltln dllaurate, dibutyltin diacetate, dioctyltln benzoate, dibutyltin benzoate. dioctyltln dlbenzoate, and dibutyltin dibenzoate. Of these, aromatic carboxylates of a dialkyltin are preferred from the viewpoint of low-temperature curing property. The content of the tin compound is not limited precisely, but can be varied widely depending on the performance that the resulting cationic electrodeposition coating Is required to have. The tin content is usually adjusted to fall within a range of from 0.01 to 8.0 wt%. preferably from 0.05 to 5.0 wt%, based on 100 wt% of the solid content of the cationic resin composition in the cationic alectrodeposition coating composition. In addition, the cationic resin composition of the present invention may further contain a coloring pigment, body pigment, organic solvent, pigment dispersant and/or surface adjuster as needed. [0iii?T The cationic electrodeposition coating composition composed of the cationic resin composition can be applied onto the surface of a desired base material by cationic electrodeposition coating method. In the ordinarily-employed electrodeposition coating method, a coating composition is diluted with deionized water or the like to give a solid content concentration of about 5.0 to 40 wt%, followed by control of the pH within a range of 5.5 to 9.0 to prepare an electrodeposition coating bath. In the resulting coating bath controlled to have a bath temperature of from 15 to 35" C, electrodeposition coating can be performed under a load voltage of 100 to 400V. Although there is no particular limitation imposed on the thickness of the film formed by cationic electrodeposition coating using the composition, it preferably ranges from 10 to 40 um in terms of the cured film. Baking temperature of a film usually ranges from 120 to 200°C on the surface of a substance to be coated, preferably 140 to 180oC. Baking is performed for 5 to 60 minutes, preferably about 10 to 30 minutes. It is preferred to maintain the baking temperature on the surface of the substance for these minutes. The cationic resin composition of the present invention can be used for, as well as cationic electrodeposition coating, electrostatic coating as a solvent type coating or roll coating as an anticorrosive primer of a steel plate. It is also usable as a two-part room-temperature curing coating or adhesive instead of a blocked isocyanate curing agent. [Examples] The present Invention will hereinafter be described in further detail by Examples. It should however be borne in mind that the present invention is not limited to or by them. All the designations of "part" or "parts" and "%" mean part or parts by weight and wt%, respectively. Preparation of an amino-containing epoxy resin Preparation Example 1 After the addition of 1143 g of "EPICOAT 828EL" (epoxy resin, trade name; product of Japan Epoxy Resins Co.. Ltd.. epoxy equivalent: 190, molecular weight: 380), 457 g of Bisphenol A and 0.2 g of dimethylbenzylamine, the resulting mixture was reacted at 130°C to give an epoxy equivalent of 800. The reaction mixture was then diluted with 100 g of butyl cellosolve. To the diluted mixture were added 160 g of diethanolamine and 65 g of ketimine-blocked diethylenetriamirle, followed by reaction at 120°C for 4 hours. To the reaction mixture was added 355 g of butyl cellosolve, whereby an amino-containing epoxy resin (A-1) having an amine value of 62 mg KOH/g, and a solid content of about 80% was obtained. Preparation Example 2: Preparation of an acrylic resin (al) for modification Polymerizable unsaturated monomers and organic solvent to be used in this Example were all fed with a nitrogen gas for 1 hour for deaeration (deoxidization) prior to use. In a reaction container equipped with a thermometer, a thermostat, an agitator, a reflux condenser and a dropping funnel, 30 g of propylene glycol monomethyl ether was charged as a solvent. While feeding a nitrogen gas, the solvent was heated to 115C. Then, a mixture containing, as polymerizable unsaturated monomers, 10 g of styrene, 20 g of methyl methacrylate, 36 g of n-butyl methacrylate, 30 g of 2-hydroxyethyl methacrylate, and 4 g of acrylic acid and, as a radical polymerization initiator, 7 g of 2,2'-azobis(20methylbutylonitrile) was added dropwise over 3 hours. After the reaction mixture was allowed to stand at 115°C for 1 hour, 0.5 part of 2,2'-azobis(2-methylbutylonitrile) and 5 g of propylene glycol monomethyl ether were added dropwise over 1 hour. The reaction mixture was allowed to stand at 115C for 1 hour to yield an acrylic resin (al) for modification having a solid content of about 75%. The resulting acrylic resin (al) for modification was found, to have a number-average molecular weight of about 3000. Preparation Example 3 After the addition of 1018 g of "EPICOAT BZBEL" (epoxy resin, trade name; product of Japan Epoxy Resins Co., Ltd., epoxy equivalent: 190, molecular weight: 380), 382 g of Bisphenol A and 0.2 g of dimethylbenzylamine, the resulting mixture was reacted at ISO'C to give an epoxy equivalent of 700. The reaction mixture was then diluted with 100 g of butyl cellosolve. To the diluted mixture were added 280 g of the acrylic resin (al) for modification obtained in Preparation Example 2, 153 g of diethanolamlne and 65 g of a ketimine-blocked dlethylenetriamine, followed by reaction at 120'C for 4 hours. To the reaction mixture was added 288 g of butyl cellosolve, whereby an amino-containing epoxy resin (A-2) having an amine value of 60 mg KOH/g and a solid content of 80% was obtained. The compositions of the resulting amino-containing epoxy resins are shown in Table 1. [Table 1] Preparation of amino-containing acrylic resin Preparation Example 4 (for Example) Polymerizable unsaturated monomers and organic solvent to be used in this Example were all fed with a nitrogen gas for 1 hour for deaeration (deoxidization) prior to use. In ,a reaction container equipped with a thermometer, a thermostat, an agitator, a reflux condenser and a dropping funnel were charged 10 parts of butyl cellosolve and 20 parts of methyl isobutyl ketone as solvents. While feeding a nitrogen gas, the solvents were heated to 115°C. A mixture containing, as polymerizable unsaturated monomers, 10 parts of styrene, 40 parts of methyl methacrylate, 10 parts of n-butyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, 20 parts of "FM-6" (polycaprolactone-modified hydroxyethyl methacrylate/ trade name; product of Daicel Chemical Industry, number-average molecular weight: 814). and 15 parts of glycidyl methacrylate and, as a radical polymerization initiator, 5 parts of 2,2'- azobis(2-methylbutylonitrile) was added dropwise over 3 hours. After the reaction mixture was allowed to stand at 115°C for 1 hour, 0.5 part of 2,2'-azobis(2-methylbutylonitrile) and 5 parts of methyl isobutyl ketone were added dropwise over 1 hour. The reaction mixture was allowed to stand at IIS'C for 1 hour to yield an acrylic copolymer solution. The resulting acrylic copolymer was found to have a number-average molecular weight of about 4000. The acrylic copolymer solution was maintained at 115°C and 10.8 parts of diethanolamine was added thereto. The resulting mixture was then heated to 120°C. After the reaction mixture was kept at the same temperature for 5 hours, it was cooled, whereby an amino-containing acrylic resin No. 1 having a solid content of about 75% was obtained. Preparation Examples 5 and 6 (for Examples) In a similar manner to Preparation Example 4 except for the compositions as shown in Table 2. amino-containlng acrylic resins Nos. 2 and 3 were obtained. Preparation Examples 7 and 8 (for Examples) In a similar manner to Preparation Example 4 except for the compositions as shown in Table 2, amino-containing acrylic resins Nos. 4 and 5 were obtained. [ 00351" [Table 2] (Note 2) "FM-e" (trade name of polycaprolactone-tnodlfled hydroxyethyl methacrylate, product of Daicel Chemical Industries, Ltd., number-average molecular weight: 814) (Note 3) "PM-S" (trade name of polycaprolactone-modified hydroxyethyl methacrylate, product of Daicel Chemical Industries. Ltd., number-average molecular weight: 472) (Note 4) "FA-5" (trade name of polycaprolactone-modified hydroxyethyl acrylate, product of Daicel Chemical Industries, Ltd., number-average molecular weight: 686) (Note 5) "FA-1" (trade name of polycaprolactone-modified hydroxyethyl acrylate. product of Daicel Chemical Industries, Ltd., number-average molecular weight: 230) Preparation Example 9: Preparation of blocked polyisocyanate curing agent (alicycllc) To 222 g of isophorone diisocyanate and 44 g of methyl isobutyl ketone, was added dropwise 174 g of methyl ethyl ketoxime in portions at 50°C, whereby a blocked polyisocyanate curing agent No. 1 having a solid content of 90% was obtained. Preparation Example 10: Preparation of blocked polyisocyanate curing agent (aromatic) After the addition of 270 g of "M-200' (trade name of crude MDI; product of Mitsui Kagaku) and 60 g of methyl isobutyl ketone, the resulting mixture was heated to 70*0. After 273 g of diethylene glycol monoethyl ether was added in portions, the mixture was heated to 90°C. While maintaining the temperature, sampling was conducted periodically. Disappearance of the absorption of an unreacted isocyanate was confirmed by infrared absorption spectrum, whereby a blocked polyisocyanate curing agent No. 2 having a solid content of 90% was obtained. Preparation Example 11: Preparation of Emulsion No. 1 A mixture of 37.5 parts of the amino-containing epoxy resin (A-1) (solid content: 30 parts) obtained in Preparation Example 1 and having a solid content of 80%, 53.3 parts (solid content: 40 parts) of the amino-containing acrylic resin No. 1 obtained in Preparation Example 4 and having a solid content of 75%, 33.3 parts (solid content: 30 parts) of the blocked polyisocyanate curing agent No. 1 having a solid content of 90% and 8,2 parts of formic acid having a solid content of 10% was stirred uniformly. To the reaction mixture, 163.4 parts of deionized water was added dropwise over about 15 minutes while vigorously stirring, whereby a cationic electrodeposition coating emulsion No. 1 having a solid content of 34% was obtained. Preparation Examples 12 to 16: Preparation of Emulsions Nos. 2 to 6 Emulsions Nos. 2 to 6 having the compositions as shown in Table 3 were obtained. [Table 3] Preparation Example 17: Preparation of pigment-dispersed paste A pigment-dispersed paste having a solid content of 55.0% was obtained by mixing 5.83 parts (solid content: 3.5 parts) of a quaternary ammonium salt type epoxy resin having a solid content of 60%, 14.5 parts of titanium white, 0.4 part of carbon black. 7.0 parts of a body pigment, 2,0 parts of bismuth hydroxide and 2.24 parts of delonized water. Examples and Comparative Examples Example 1: Preparation of Catlonic electrodeposition coating No. 1 To 294 parts (solid content: 100 parts) of the cationic electrodeposltlon coating emulsion No. 1 having a solid content of 34% were added 49.8 parts (solid content: 27.4 parts) of a pigment-dispersed paste having a solid content of 55% and 293.2 parts of deionized water, whereby a cationlc electrodeposltlon coating No. 1 having a solid content of 20% was obtained. Examples 2 to 4, & Comparative Examples 1 and 2 Cationic electrodeposltlon coatings Nos. 2 to 6 having the compositions as shown in Table 4 were prepared. Tests were conducted on them under the below-described conditions and the results are also shown in Table 4. Preparation of a test plate Electrodeposition coating of a 0.8 x 150 x 70 mm cold-rolled dull-finish steel sheet or galvanized steel sheet, each chemically treated with "Palbond #3020" (trade name of a zinc phosphate treating agent; product of Nihon Parkerizing Co., Ltd.) was performed in each of the cationic electrodeposltlon coating compositions obtained in the above-described Examples and Comparative Examples. The resulting test plate was then baked at 170°C for 20 minutes by using an electric hot air drier. The plate thus obtained was tested under the below-described conditions. The results of the test are shown in Table 4. In the corrosion resistance test (Note 7) using a galvanized steel sheet, a deterioration in the corrosion resistance is presumed to occur because a stress appears between the separated layers of the film and swelling (in the strain form) tends to be formed easily. [Table 4] Table 4: Compositions and test results of cationic (Note 6) Weatherability: After a test plate (a chemically-treated cold-rolled steel plate) was exposed to a 200-hour accelerated weathering test using a sunshine weatherometer, its gloss retention percentage was studied in accordance with 60° gloss of JIS K-5400 7.6 (1990). (Note 7) Corrosion Resistance: Cross-cuts were made with a knife through an electrodeposlted film of each electrodeposited test plate (chemically-treated galvanized steel plate) to a base material. The resulting plat© was subjected to a salt spray exposure test for 840 hours in accordance with JIS Z-2371 and lengths of the rust and blister starting from the knife cut were measured to evaluate corrosion resistance. (Note 8) Ultrafilterability: A zinc phosphate treating liquid (5000 ppm) was added to a cationic electrodeposition coating through an UF membrane 'NTU-212" (trade name of UF flat membrane; product of Nltto Denko Corporation) for laboratory test. After circulation of the coating by using an apparatus as illustrated in FIG. l, circulation of the cationic electrodeposition coating is stopped, followed by application of a stress on the UF film to test a recovery ratio (permeation amount) of the filtrate after stoppage. Indicated at numeral 1 in FIG. 1 is a motor for circulating a coating, 2 a container having an UF membrcine placed therein; and 3 a cationic electrodeposition bath. The coating is fed by 4 from this bath and is circulated at 1. The coating circulated at 1 is fed to 2 and separated into a liquid 3 and the coating. The coating thus separated is returned into the cationic electrodeposition bath by 5. The amount of the liquid 3 is measured at 6. A: a recovering ratio exceeding 85%. B; a recovering ratio of 75 to 85%. C; a recovering ratio less than 75%. (Note 9) Adhesion: A test plate (a chemically treated galvanized steel sheet) was prepared by electrodeposition of each cationic electrodeposition coating thereon, followed by baking to cure. It was allowed to stand for 240 hours in a 50°C blister box. On the resulting plate, a 2 mm Crosshatch pattern was scribed and a peeling test was conducted using a. Cellophane adhesive tape. A: no problems B: 95 to 99/100 remained. , CJ less than 95/100 remained. (Note 10) Stability of a coating 1: The remaining amount of the paint after the above-described U/F ability test was measured. A: less than 10' ml/L B: 10 to 20 mg/L C: exceeding 20 mg/L (Note 11) Stability of a coating 2: After the above-described U/F ability test, electrodeposition was conducted using the cationic electrodeposition coating composition and its coating finish was evaluated. A: good with no problems. B: surface roughening and lowering in glaze due to skin absorption are observed. C; severe surface roughening and lowering in glaze due to sHin absorption. [Advantageous effects of the Invention] A cationic electrodeposition coating composition capable of forming a film good in both weatherability and corrosion resistance and being excellent in adhesion and moisture resistance, and moreover, long-terra stability of the coating can be obtained by incorporating therein the cationic resin composition of the present invention comprising an amino-containing epoxy resin (A), an amino-containing acrylic resin (B) and a blocked polyisocyanate curing agent (C) in amounts of 5 to 80 wt%, 5 to 80 wt% and 10 to 40 wt%, respectively, each based on the total weight of the solid content; and having a difference in solubility parameter between the amino-containing epoxy resin (A) and the amino-containing acrylic resin (B) ranging from 0 to 0.7 can provide a film having good weatherability and corrosion resistance. Since the icind of monomers constituting the resin (B) and their mixing ratio are specified to allow an emulsion containing the resin (B) to have many hydroxyl groups, when a coating containing such a resin (B) is precipitated on the interface of a steel plate, adhesion starts from this point and the coating contributes to an improvement of corrosion resistance. Furthermore, by specifying the kind of monomers constituting the resin (B) and their mixing ratio, weatherability is improved, because, in an emulsion formed of shell (base resin) and core (curing agent), an amine-added acrylic resin (B) is formed in the outer layer of the shell and an aniine-added epoxy resin (A) is formed inside of the shell. A difference in the solubility parameter within a range of from 0 to 0.7 provides the coating with good stability without causing destruction of emulsion particles even if a stress is applied to the coating for a long period of time. [Brief Description of the Drawing] FIG. 1 illustrates a model of a U/F ability testing apparatus for laboratory use. WE CLAIM; 1. A cationic electrodeposition coating composition comprising a combination of components A, B and C in amounts of 5 to 80% by wt, 5 to 80% by wt and 10 to 40% by wt respectively based on the total solid content of A, B and C wherein component A is an amino containing epoxy resin such as herein described having an average molecular weight of 500 to 5000; component B is an amino containing acrylic resin such as herein described and component C is a known blocked polyisocyanate curing agent. 2. The cationic electrodeposition coating composition as claimed in claim 1, wherein the amino-containing acrylic resin (B) is obtained by adding an amino-containing compound to a resin obtained by radical copolymerization reaction of a mixture of 5 to 40 wt% of the polylactone-modified hydroxyl-containing radical copolymerizable acrylic monomer, obtained by adding a lactone to hydroxyethyl (meth)acrylate is represented by the formula (1) or (2), 2 to 30 wt% of glycidyl (meth)acrylate and 30 to 93 wt% of another radical copolymerizable monomer, each based on the total solid content of the monomers constituting the amino-containing acrylic resin (B). 3. The cationic electrodeposition coating composition as claimed in claim 1 or 2, wherein the lactone is e-caprolactone. 4. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 3, wherein the amino-containing epoxy resin (A) has an amine value ranging from 40 to 80 mg KOH/g. 5. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 4, wherein the amino-containing epoxy resin (A) has a primary hydroxyl value ranging from 10 to 200 mg KOH/g. 6. The cationic electrodeposition coating composition as claimed in claims 1 to 5, wherein the amino-containing epoxy resin (A) has a number-average molecular weight of from 500 to 5000. 7. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 6, wherein the amino-containing epoxy resin (A) has a solubility parameter 6A of from 9.5 to 11.5. 8. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 7, wherein the amino-containing acrylic resin (B) has a hydroxyl value of from 10 to 300 mg KOH/g. 9. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 8, wherein the amino-containing acrylic resin (B) has an amine value of from 10 to 125 mg KOH/g. 10. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 9, wherein the amino-containing acrylic resin (B) has a number-average molecular weight of from 10000 to 50000.

Full Text

[Detailed Description of the Invention]
[Technical Field to which the Invention Belongs]
The present invention relates to a cationic resin composition capable of providing a cationic electrodeposition coating having excellent weatherability and corrosion resistance, and good long-term bath stability.
[Prior Art and Problems that the Invention is to Solve]
Cationic electrodeposition coatings have been used for

wide ranging purposes including automobile undercoating a,nd those having vaxious characteristics have been developed.
As Inventions intended to satisfy both weatherabillty and corrosion resistance, those having an ©poxy resin and an acrylic resin and forming, on a steel plate side, a layer rich in. the epoxy resin superior in corrosion resistance and, on the film surface aide, the other layer rich in the acrylic resin are disclosed in Japanese Patents Laid-open Nos. 333528/1996, 292131/1998, 345394/2000 and 234116/2001,
In the cationic electrodeposition coating, a film is formed by filling an electrodeposition bath of 5 to 300 m" with a cationic electrodeposition coating, applying a voltage to an automobile body or part which is to be coated, thereby depositing a film thereon, and then baking anjd drying the film.
Application of a cationic electrodeposition coating requires, in addition to an electrodeposition! tank, collecting and water washing equipment, UF eq|uipment and precise filtration equipment. The cationic electrodeposition coating receives many stresses such as mechan|ical one upon circulation or washing of a collected liquid [with water, mechanical stress due to a pressure differencje upon passing through the filtration equipment, mechanical Istress occurring upon suction of a pump in the electrodeposltl|on tank or delivery, and chemical stress owing to contaminatlon by a degreased liquid or chemical liquid brought in by an automobile body or volatilization of a solvent.

When the amount of substances to be coated decreases, a decline in the loss of a coating occurs, leading to a decrease in the amount of the coating to be supplemented. The remaining coating inevitably receives mechanical or chemical stress as described above for a long period of time. For example, 1 turnover/month (replaced ratio: about 65%/month) means that it takes a month to add, to an electrodepositlon tank, a coating in an amount to make up for the loss by line coating.
In an electrodepositlon line of 0.1 turnover/month (which line may hereinafter be called "low-speed turnover line"). It takes 10 months for 65% of a coating in an electrodepositlon tank to be replaced. The remaining 35% of the coating inevitably undergoes a stress for more than 10 months.
For a cationic electrodepositlon coating, long-term stability of the coating is therefore important. Application of a conventional cationic electrodepositlon coating, which contains resins drastically different in a solubility parameter, to a low-speed turnover coating line sometimes causes problems such as deterioration in coating finish, clogging upon precise filtration, clogging upon ultrafiltration and disturbance of maintenance such as cleaning by agglomerates appearing in an electrodepositlon tank. There is accordingly a demand for the development of a cationic electrodepositlon coating excellent in long-term stability of the coating and having both weatherability and

corrosion resistance.
[Means for Solving the Problems]
The present inventors have proceeded with an extensive investigation with a view to overcoming the above-described problems and as a result, invented a cationic electrodeposition coating excellent in stability of the coating and good in both weatherability and corrosion resistance by mixing an amino-containing epoxy resin (A); an amino-containing acrylic resin (B) available by adding an amino-containing compound to a copolymer resin available by-' radical copolymerization of a polylactone-modified hydroxyl-containing radical copolymerizable monomer, which is obtained by adding a lactone to a hydroxyl-containing acrylic monomer, and a glycidyl (meth)aerylate as essential components, and another radical copolymerizable monomer; and a blocked polyisocyanate curing agent (C).
Accordingly, the present invention provides a cationic electrodeposition coating composition comprising a combination of components A, B and C in amounts of 5 to 80% by wt, 5 to 80% by wt and 10 to 40% by wt respectively based on the total solid content of A, B and C wherein component A is an amino containing epoxy resin such as herein described having an average molecular weight of 500 to 5000; component B is an amino containing acrylic resin such as herein described and component C is a known blocked polyisocyanate curing agent.

[Mode for Carrying Out the Invention]
The present invention relates to a cationic resin composition excellent in stability of the coating, weatherabllity and corrosion resistance. Amino-containing epoxy resin (A) :
Examples of the amino-containing epoxy resin include (I) an adduct of a polyepoxy compound and a primary mono- or-poly-amine, a secondary mono- or poly-amine or a primary and secondary polyamine mixture (for example, that described in U.S. Patent No, 3.984.299); (II) an adduct of a polyepoxide compound and a secondary mono- or polyamine having a ketimine-blocked primary amino group; and (III) a reaction product available by etherification of a polyepoxide compound and a hydroxyl compound having a ketimine-blocked primary amino group (for example, that described in Japanese Patent Laid-open No. 43013/1984).

As the epoxide compound to be used for the preparation of the above-described amine-added epoxy resin, suited is a compound having, in one molecule thereof, at least two epoxy groups and having usually a number-average molecular weight of at least 2000. preferably from 400 to 3,000. more preferably from 800 to 2,000, with that available by the reaction between a polyphenol compound and epichlorohydrin being particularly preferred.
Examples of the polyphenol compound usable for the formation of the polyepoxide compound include bis(4-hydroxyphenyl)-2,2-propane, 4,4-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-tert-butyl-phenyl)-2,2-propane, bis(2-4-hydroxy-tert-butyl-phenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane, tetra(4-hYdroxyphenyl)-l,1,2,2-ethane. 4.4-dihydroxydiphenylsulfone, phenol novolak, cresol novolak.
The polyepoxide compound partially reacted with a polyol. polyether polyol, polyester polyol, polyamidoamine, polycarboxylic acid, or polyisocyanate compound Is also usable. Alternatively, a polyepoxide compound obtained by graft polymerization with e-caprolactone or an acrylic monomer is usable.
As the amino-containing epoxy resin (A), suited is that having a number-average molecular weight ranging from 500 to 5,000, especially from 600 to 4,500, more preferably from 800

to 4,000, an amine value ranging from 40 to 80 mg KOH/g, a primary hydroxyl value ranging from 10 to 200 mg KOH/g and a solubility parameter 6;, ranging from 9.5 to 11.5. The solubility parameter is a parameter as shown in the following (Note 1).
(Note 1) Solubility parameter: The solubility parameter (SP value) represents a measure of an intermolecular action between liquid molecules. In the present invention, the SP value is calculated in accordance with the following equation (1):

wherein, SP1, SP2, ... and SP„ represents the SP of the respective monomers, and fw1, fW2, •••, and fw„ represent weight fractions of the respective monomers based on a total weight of the monomers. The SPs of polymerizable monomers are written briefly in "J. Paint Technology, 42, 176(1970)". The monomer not listed in the above literature, reference may be made to a catalog issued by a manufacturer.
The above-described amino-containing epoxy resin (A) can form a film excellent in weatherability and corrosion resistance by being added, together with an amino-containing acrylic resin (B), to a cationic electrodeposition coating.
Amino-containing acrylic resin (B):
The amino-containing acrylic resin (B) to be used in the present invention is prepared by obtaining a copolymer resin by the radical copolymerization of, as essential

components, a polylactone-modlfied hydroxyl-containing radical copolymerizable monomer (b-1), which is obtained by adding a lactone to a hydroxyl-containing monomer (b) and is represented by the following formula (1) or (2):
-tC-henfiCcal formula b]—
(wherein, R^ represents H or an alkyl group, R^ represents any one of -(CHJ^-, -(CO)O-(CHj)„- and -O-(CO) - (CH2)„-. 1 stands for an integer of 3 to 10, m stands for an integer of 4 to 8 and n stands for an integer of 1 to 10),
[ Chemiual foi'iiiuld 6 ] '
(wherein, Ri represents H or an alkyl group, R^ represents any one of -(CHJ^-, -(CO)0-(CHJ„- and -O-(CO) - (CHj)^-, 1 stands for an integer of 3 to 10, k stands for an integer of 0 to 4 and n stands for an integer of 1 to 10), and glycidyl (meth)aerylate (b-2), and another radical copolymerizable monomer (b-3); and then adding an amino-containing compound (b-4) to the resulting copolymer resin.
Examples of the hydroxyl-containing acrylic monomer (b) include 2-hydroxyethyl (meth)aerylate, 2-hydroxypropyl (meth)aerylate, 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate. Addition of a lactone thereto can yield a polylactone-modified hydroxyl-containing radical copolymerizable monomer (b-1) represented by the formula (1)

or (2).
The addition products of 2-hydroxyethyl (meth)aerylate and caprolactone include, for example, "PLACCEL FA-3" and "PLACCEL PM-S" (each, trade name; proiiuct of Dalcel Chemical Industries, Ltd.). They may be used either singly or in combination.
The content of the polylactone-modified hydroxyl-containing radical copolymertzable monomer (b-1) ranges from 5 to 40 wt%. preferably from 10 to 35 wt%, based on the total amount of the monomer components constituting the resin (B).
Contents of the polylactone-modified hydroxyl-containing radical copolymerizable monomer (b-1) exceeding 40 wt% soften the resin (B), thereby deteriorating the corrosion resistance of the electrodeposited film. Those less them 5 wt%, on the other hand, lower the compatibility between the resin (B) and the amino-containing epoxy resin (A), thereby deteriorating the stability of the coating and also the coating finish (film appearance).
In order to impart the monomer with water solubility, an active-hydrogen-containing amine compound may be added to glycidyl (meth)acrylate (b-2) or they may be subjected to ring-opening copolymerization to add the active-hydrogen-containing amine compound to the terminal of glycidyl (meth)acrylate. The content of glycidyl (m6th)acrylate (b-2) ranges from 2 to 30 wt%, preferably from 5 to 25 wt% based on the total eimount of the monomer components constituting

the resin (B).
When the content of glycidyl (meth)acrylate (b-2) exceeds 30 wt%, a film formed using a cationic electrodeposition coating containing the resulting resin (B) has deteriorated weatherability. Contents less than 2 wt%, on the other hand, deteriorate the water dispersibility of the resin (B).
As the another radical copolymerizable monomer (b-3), hydroxyl-containing acrylic monomers (b) similar to those described above are usable. Examples include 2-hydroxy6thyl (meth)acrylate, 2-hydroxypropyl (meth)acrylatey 4-hydroxybutyl (meth)aerylate and 2-hydroxyethyl (methlacrylate.
Amino-containing acrylic monomers are also usable. Examples include N,N-dimethylaininoethyl (meth)acrylate, N,N-diethylaminoethyl (me th) aery late, N,N-dimethyleiminopropyl (meth)acrYlat6, N,N-di-t-butylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylamide.
In addition, usable are methyl (meth)acrylate, ethyl (meth)aerylate, n-propyl (meth)aerylate, isopropyl (meth)aerylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)aerylate,CYClohexyl (m©th)acrylate, 2-ethylhexyl (meth)acrylate, styrene, vinyl toluene and a-methylstyrene. Such a monomer (b-3) is used in an amount of from 30 to 93 parts by weight, based on the total amount of the monomer components constituting the resin (B) . Amounts less than 30 parts by weight deteriorate

corrosion resistance and weatherablllty, while those exceeding 90 parts by weight deteriorate compatibility with the amino-containing resin and water dispersibility.
Examples of the organic solvent to be used for radical copolymerization include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl isobutyl ketone and cyclohexanone, and alcoholic solvents such as n-butanol, ethyl cellosolve. butyl cellosolve, methoxypropanol, and diethylene glycol monobutyl ether. As the organic solvent, they may be used either singly or as a mixture of a plurality of them.
The radical copolymerization reaction can usually be carried out by reacting the above-described monomer components in the above-described organic solvent maintained at from about 50°C to. SOO'C, preferably from about 60'C to 250'C for about one hour to 24 hours, preferably from about 2 hours to 10 hours under an inert gas such as nitrogen gas.
Examples of the amino-containing compound (b-4) to be added to impart water dispersibility include primary mono- or polyamlnes, secondary mono- or polyamines, a mixture of primary and secondary polyamines, secondary mono- or polyamines having a ketimine-blocked primary amino group, and hydroxyl compounds having a ketimine-blocked primary amino group. More specifically, use of diethylamine, diethanolamine or ketimine-blocked diethylenetriamine is

preferred.
The ainino-containing acrylic resin (B) has a number-average molecular weight ranging from 1,000 to 50,000, preferably from 2,000 to 20,000. When the number-average molecular weight is less than 1,000, the emulsion has impaired stability, while when it exceeds 50,000, the smoothness on the film surface is impaired. The number-average molecular weight outside the above-described range is therefore not preferred.
The amino-containing acrylic resin (B) having an amine value reunging from 10 to 125 mg KOH/g, a hydroxyl value ranging from 10 to 300 mg KOH/g and a solubility parameter 6^^ (Note 1) ranging from 9.5 to 11.5 is suited in the present invention.
When an amine value exceeds 125 mg KOH/g, hydrophilic properties of the resin (B) increase, resulting in a deterioration in the performances of the electrodeposited film such as weatherability and corrosion resistance. Amine values less than 10 mg KOH/g, on the other hand, cause a drastic worsening in water dispersibility of an emulsion of the resin (A).
When the hydroxyl value exceeds 300 mg KOH/g, hydrophilic properties of the resin (B) increase, resulting in a deterioration in the corrosion resistance of the electrodeposited film. The hydroxyl value less than 10 mg KOH/g, on the other hand, lowers water dispersibility and a

cross-linking density, leading to a deterioration in the film performance.
When the solubility parameter 6^, is less than 9.5, the compatibility with the amino-containing epoxy resin lowers. Solubility parameters exceeding 11.5, on the other hand, lead to a deterioration in weatherability.
In the present invention, a difference in the SP value between the amino-containing epoxy resin (A) and the amino-containing acrylic resin (B) is preferably 0 to 0.7. The difference of the SP value exceeding 0.7 may cause a deterioration in the long-term stability of the coating, or cause a layer separation of the film containing both resins, thereby deteriorating adhesion or moisture resistance.
Blocked polyisocyanate curing agent (C):
The blocked polyisocyanate curing agent (C) is a product of addition reaction between a polyisocyanate compound and an isocyanate blocking agent in a stoichiometric ratio. As the polyisocyanate compound, conventional ones can be used. Examples include aromatic, aliphatic or alicyclic polyisocyanate compounds such as trylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate (usually called "MDI"), crude MDEi, bisCisocyanatomethyDcyclohexane, tetramethylen© diisocyanate, hexamethylene diisocyanate, methylene diisocyanate and isophorone diisocyanate; cyclic polymers of these

polyisocyanate compounds and isocyanate-biuret; and terminal-isocyanate-containing compounds available by reacting an excess amount of such an isocyanate compound with a low-molecular active-hydrogen-containing compound such as ethylene glycol, propylene glycol, trimethylolpropane, heKanetriol or castor oil. These polyisocyanate compounds may be used either singly or in combination.
The above-described isocyanate blocking agent is added to the isocyanate group of a polyisocyanate compound to block it. The blocked polyisocyanate compound prepared by the addition reaction is stable at normal temperature, but when heated at a film baking temperature (usually, about 100 to 200'C), it desirably causes dissociation of the blocking agent and regenerates the free isocyanate group.
Examples of the blocking agent capable of satisfying the above requirements include lactam compounds such as s-caprolactam and Y-caprolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; aliphatic alcohols such as n-butanol and 2-ethylh.exanol; aromatic alkyl alcohols such as phenylcarbinol and meth-ylpbenylcarbinol; and ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether.
As well as these blocking agents, blocked polyisocyanate crosslinking agents (II) containing, as a blocking agent, a diol containing two hydroxyl groups

different in reactivity and having a molecular weight of 76 to 150 or a carboxyl-containing diol having a molecular weight of 106 to 500 may be used. [0023]
The above-described diol contains two hydroxyl groups different in reactivity, for example, a primary hydroxyl group and a secondary hydroxyl group, a primary hydroxyl group and a tertiary hydroxyl group, or a secondary hydroxyl group and a tertiary hydroxyl group; and has a molecular weight of 76 to 150. Examples of the diol having two hydroxyl groups different in reactivity include propylene glycol, dipropylene glycol, 1,3-butanediol, 1,2-butanediol, 3-methyl-l,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-l,3-pentanediol, 1,5-hexanediol and 1.4-hexanediol.
Of these, propylene glycol is preferred from the viewpoints of the reactivity of the blocked polyisocyanate, a reduction in heating loss, and storage stability of the resulting coating. The reaction with an isocyanate group usually starts first with the hydroxyl group having a higher reactivity, thereby blocking the isocyanate group.
The above-described carboxyl-containing diol embraces a carboxyl-containing diol having a molecular weight of 106 to 500. It is able to have improved low-temperature dissociation property and in turn, improved low-temperature curing property, by having, in the molecule thereof, a carboxyl group. Particularly, use of an organotin compound

as a curing catalyst brings about a drastic improvement in the low-temperature curing property.
Examples of the carboxyl-containing diol include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, dimethylolvaleric acid and glyceric acid.
The cationic resin composition of the cationic electrodeposition coating contains the amino-containing epoxy resin (A), amino-containing acrylic resin (B), and blocked polyisocyanate curing agent (C) and it preferably contains them in amounts of 5 to 80 wt%, 5 to 80 wt% and 10 to 40 wt%, respectively, each based on the total solid content of the resin (A), resin (B) and curing agent (C).
Neutralization and dispersion of the cationic resin composition are conducted as follows. After the amino-containing epoxy resin (A), amino-containing acrylic resin (B) and blocked polyisocyanate curing agent (C) are mixed sufficiently, a dissolved varnish thus obtained is added with one or more of neutrallzers selected from formic acid, acetic acid, lactic acid, propionic acid, citric acid, malic acid and sulfamic acid. The resulting mixture is dispersed in water to yield an emulsion for a cationic electrodeposition coating.
Amounts of the amino-containing epoxy resin (A) less than 5 wt% lower corrosion resistance, while those exceeding 80 wt% lower weatherability. Amounts of the amino-containing acrylic resin (B) less than 5 wt% lower weatherability, while

those exceeding 80 wt% lower corrosion resistance. Amounts of the blocked polyisocyanate curing agent (C) less than 10 wt% lower the curing property, while those exceeding 40 wt% cause a deterioration in the storage stability of the coating.
Addition of acetic acid and/or formic acid as the neutralizer is preferred, because it brings about excellent coating finish, throwing power of electrolytic coating, low-temperature curing property and stability of the coating.
It is preferred to add, to the cationic resin composition, a bismuth compound as a rust preventive. Although no particular limitation is imposed on the bismuth compound, bismuth oxide, bismuth hydroxide, basic bismuth carbonatey bismuth nitrate and bismuth silicate can be given as examples. Of these, bismuth hydroxide is preferred.
Alternatively, a bismuth salt of an (oxy)organic acid prepared by reacting the above-described bismuth compound with at least two organic acids, at least one of which is an aliphatic hydroxycarboxylic acid, may be used.
Examples of the aliphatic carboxylic acid used in the preparation of the bismuth salt of an (oxy)organic acid may include glycolic acid, glyceric acid, lactic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolvaleric acid, tartaric acid, malic acid, hydroxymalonic acid, dihydroxysuccinic acid,
trihydroxysuccinic acid, methylmalonic acid, benzoic acid and citric acid.

The content of the bismuth compound in the cationic electrodeposition coating is not limited precisely, but can be varied widely depending on the performance that the coating is required to have. The content of.the bismuth compound is adjusted within a range of 0.01 to 10 parts by weight, preferably from 0.05 to 5 parts by weight, based on 100 parts by weight of the total solid content of the cationic resin composition of the cationic electrodeposition coating composition including the amino-containing epoxy resin (A), amino-containing acrylic resin (B) and blocked polyisocyanate curing agent (C).
The cationic electrodeposition coating composition may contain, as a curing catalyst, a tin compound in addition to the above-described components. Examples of the tin compound Include organotin compounds such as dibutyltin oxide and dioctyltln oxide; and aliphatic or aromatic carboxylates of a dialkyltin such as dibutyltin dilaurate, dioctyltln dllaurate, dibutyltin diacetate, dioctyltln benzoate, dibutyltin benzoate. dioctyltln dlbenzoate, and dibutyltin dibenzoate. Of these, aromatic carboxylates of a dialkyltin are preferred from the viewpoint of low-temperature curing property.
The content of the tin compound is not limited precisely, but can be varied widely depending on the performance that the resulting cationic electrodeposition coating Is required to have. The tin content is usually adjusted to fall within a range of from 0.01 to 8.0 wt%.

preferably from 0.05 to 5.0 wt%, based on 100 wt% of the solid content of the cationic resin composition in the cationic alectrodeposition coating composition.
In addition, the cationic resin composition of the present invention may further contain a coloring pigment, body pigment, organic solvent, pigment dispersant and/or surface adjuster as needed. [0iii?T
The cationic electrodeposition coating composition composed of the cationic resin composition can be applied onto the surface of a desired base material by cationic electrodeposition coating method. In the ordinarily-employed electrodeposition coating method, a coating composition is diluted with deionized water or the like to give a solid content concentration of about 5.0 to 40 wt%, followed by control of the pH within a range of 5.5 to 9.0 to prepare an electrodeposition coating bath. In the resulting coating bath controlled to have a bath temperature of from 15 to 35" C, electrodeposition coating can be performed under a load voltage of 100 to 400V.
Although there is no particular limitation imposed on the thickness of the film formed by cationic electrodeposition coating using the composition, it preferably ranges from 10 to 40 um in terms of the cured film. Baking temperature of a film usually ranges from 120 to 200°C on the surface of a substance to be coated, preferably 140 to 180oC. Baking is performed for 5 to 60 minutes, preferably

about 10 to 30 minutes. It is preferred to maintain the baking temperature on the surface of the substance for these minutes.
The cationic resin composition of the present invention can be used for, as well as cationic electrodeposition coating, electrostatic coating as a solvent type coating or roll coating as an anticorrosive primer of a steel plate. It is also usable as a two-part room-temperature curing coating or adhesive instead of a blocked isocyanate curing agent.
[Examples]
The present Invention will hereinafter be described in further detail by Examples. It should however be borne in mind that the present invention is not limited to or by them. All the designations of "part" or "parts" and "%" mean part or parts by weight and wt%, respectively. Preparation of an amino-containing epoxy resin Preparation Example 1
After the addition of 1143 g of "EPICOAT 828EL" (epoxy resin, trade name; product of Japan Epoxy Resins Co.. Ltd.. epoxy equivalent: 190, molecular weight: 380), 457 g of Bisphenol A and 0.2 g of dimethylbenzylamine, the resulting mixture was reacted at 130°C to give an epoxy equivalent of 800. The reaction mixture was then diluted with 100 g of butyl cellosolve.
To the diluted mixture were added 160 g of diethanolamine and 65 g of ketimine-blocked

diethylenetriamirle, followed by reaction at 120°C for 4 hours. To the reaction mixture was added 355 g of butyl cellosolve, whereby an amino-containing epoxy resin (A-1) having an amine value of 62 mg KOH/g, and a solid content of about 80% was obtained.
Preparation Example 2: Preparation of an acrylic resin (al) for modification
Polymerizable unsaturated monomers and organic solvent to be used in this Example were all fed with a nitrogen gas for 1 hour for deaeration (deoxidization) prior to use.
In a reaction container equipped with a thermometer, a thermostat, an agitator, a reflux condenser and a dropping funnel, 30 g of propylene glycol monomethyl ether was charged as a solvent. While feeding a nitrogen gas, the solvent was heated to 115C. Then, a mixture containing, as polymerizable unsaturated monomers, 10 g of styrene, 20 g of methyl methacrylate, 36 g of n-butyl methacrylate, 30 g of 2-hydroxyethyl methacrylate, and 4 g of acrylic acid and, as a radical polymerization initiator, 7 g of 2,2'-azobis(20methylbutylonitrile) was added dropwise over 3 hours. After the reaction mixture was allowed to stand at 115°C for 1 hour, 0.5 part of 2,2'-azobis(2-methylbutylonitrile) and 5 g of propylene glycol monomethyl ether were added dropwise over 1 hour. The reaction mixture was allowed to stand at 115C for 1 hour to yield an acrylic resin (al) for modification having a solid content of about 75%. The

resulting acrylic resin (al) for modification was found, to have a number-average molecular weight of about 3000.
Preparation Example 3
After the addition of 1018 g of "EPICOAT BZBEL" (epoxy resin, trade name; product of Japan Epoxy Resins Co., Ltd., epoxy equivalent: 190, molecular weight: 380), 382 g of Bisphenol A and 0.2 g of dimethylbenzylamine, the resulting mixture was reacted at ISO'C to give an epoxy equivalent of 700. The reaction mixture was then diluted with 100 g of butyl cellosolve.
To the diluted mixture were added 280 g of the acrylic resin (al) for modification obtained in Preparation Example 2, 153 g of diethanolamlne and 65 g of a ketimine-blocked dlethylenetriamine, followed by reaction at 120'C for 4 hours. To the reaction mixture was added 288 g of butyl cellosolve, whereby an amino-containing epoxy resin (A-2) having an amine value of 60 mg KOH/g and a solid content of 80% was obtained.
The compositions of the resulting amino-containing epoxy resins are shown in Table 1.
[Table 1]

Preparation of amino-containing acrylic resin Preparation Example 4 (for Example)
Polymerizable unsaturated monomers and organic solvent to be used in this Example were all fed with a nitrogen gas for 1 hour for deaeration (deoxidization) prior to use.
In ,a reaction container equipped with a thermometer, a thermostat, an agitator, a reflux condenser and a dropping funnel were charged 10 parts of butyl cellosolve and 20 parts of methyl isobutyl ketone as solvents. While feeding a nitrogen gas, the solvents were heated to 115°C.
A mixture containing, as polymerizable unsaturated monomers, 10 parts of styrene, 40 parts of methyl methacrylate, 10 parts of n-butyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, 20 parts of "FM-6" (polycaprolactone-modified hydroxyethyl methacrylate/ trade name; product of Daicel Chemical Industry, number-average molecular weight: 814). and 15 parts of glycidyl methacrylate and, as a radical polymerization initiator, 5 parts of 2,2'-

azobis(2-methylbutylonitrile) was added dropwise over 3 hours.
After the reaction mixture was allowed to stand at 115°C for 1 hour, 0.5 part of 2,2'-azobis(2-methylbutylonitrile) and 5 parts of methyl isobutyl ketone were added dropwise over 1 hour. The reaction mixture was allowed to stand at IIS'C for 1 hour to yield an acrylic copolymer solution.
The resulting acrylic copolymer was found to have a number-average molecular weight of about 4000. The acrylic copolymer solution was maintained at 115°C and 10.8 parts of diethanolamine was added thereto. The resulting mixture was then heated to 120°C. After the reaction mixture was kept at the same temperature for 5 hours, it was cooled, whereby an amino-containing acrylic resin No. 1 having a solid content of about 75% was obtained.
Preparation Examples 5 and 6 (for Examples)
In a similar manner to Preparation Example 4 except for the compositions as shown in Table 2. amino-containlng acrylic resins Nos. 2 and 3 were obtained.
Preparation Examples 7 and 8 (for Examples)
In a similar manner to Preparation Example 4 except for the compositions as shown in Table 2, amino-containing acrylic resins Nos. 4 and 5 were obtained. [ 00351" [Table 2]

(Note 2) "FM-e" (trade name of polycaprolactone-tnodlfled hydroxyethyl methacrylate, product of Daicel Chemical Industries, Ltd., number-average molecular weight: 814) (Note 3) "PM-S" (trade name of polycaprolactone-modified hydroxyethyl methacrylate, product of Daicel Chemical Industries. Ltd., number-average molecular weight: 472) (Note 4) "FA-5" (trade name of polycaprolactone-modified hydroxyethyl acrylate, product of Daicel Chemical Industries, Ltd., number-average molecular weight: 686) (Note 5) "FA-1" (trade name of polycaprolactone-modified hydroxyethyl acrylate. product of Daicel Chemical Industries, Ltd., number-average molecular weight: 230)
Preparation Example 9: Preparation of blocked polyisocyanate

curing agent (alicycllc)
To 222 g of isophorone diisocyanate and 44 g of methyl isobutyl ketone, was added dropwise 174 g of methyl ethyl ketoxime in portions at 50°C, whereby a blocked polyisocyanate curing agent No. 1 having a solid content of 90% was obtained.
Preparation Example 10: Preparation of blocked polyisocyanate curing agent (aromatic)
After the addition of 270 g of "M-200' (trade name of crude MDI; product of Mitsui Kagaku) and 60 g of methyl isobutyl ketone, the resulting mixture was heated to 70*0. After 273 g of diethylene glycol monoethyl ether was added in portions, the mixture was heated to 90°C. While maintaining the temperature, sampling was conducted periodically. Disappearance of the absorption of an unreacted isocyanate was confirmed by infrared absorption spectrum, whereby a blocked polyisocyanate curing agent No. 2 having a solid content of 90% was obtained.
Preparation Example 11: Preparation of Emulsion No. 1
A mixture of 37.5 parts of the amino-containing epoxy resin (A-1) (solid content: 30 parts) obtained in Preparation Example 1 and having a solid content of 80%, 53.3 parts (solid content: 40 parts) of the amino-containing acrylic resin No. 1 obtained in Preparation Example 4 and having a solid content of 75%, 33.3 parts (solid content: 30 parts) of

the blocked polyisocyanate curing agent No. 1 having a solid content of 90% and 8,2 parts of formic acid having a solid content of 10% was stirred uniformly. To the reaction mixture, 163.4 parts of deionized water was added dropwise over about 15 minutes while vigorously stirring, whereby a cationic electrodeposition coating emulsion No. 1 having a solid content of 34% was obtained.
Preparation Examples 12 to 16: Preparation of Emulsions Nos. 2 to 6
Emulsions Nos. 2 to 6 having the compositions as shown in Table 3 were obtained.
[Table 3]

Preparation Example 17: Preparation of pigment-dispersed paste
A pigment-dispersed paste having a solid content of 55.0% was obtained by mixing 5.83 parts (solid content: 3.5 parts) of a quaternary ammonium salt type epoxy resin having a solid content of 60%, 14.5 parts of titanium white, 0.4 part of carbon black. 7.0 parts of a body pigment, 2,0 parts of bismuth hydroxide and 2.24 parts of delonized water.
Examples and Comparative Examples
Example 1: Preparation of Catlonic electrodeposition coating
No. 1

To 294 parts (solid content: 100 parts) of the cationic electrodeposltlon coating emulsion No. 1 having a solid content of 34% were added 49.8 parts (solid content: 27.4 parts) of a pigment-dispersed paste having a solid content of 55% and 293.2 parts of deionized water, whereby a cationlc electrodeposltlon coating No. 1 having a solid content of 20% was obtained.
Examples 2 to 4, & Comparative Examples 1 and 2
Cationic electrodeposltlon coatings Nos. 2 to 6 having the compositions as shown in Table 4 were prepared. Tests were conducted on them under the below-described conditions and the results are also shown in Table 4.
Preparation of a test plate
Electrodeposition coating of a 0.8 x 150 x 70 mm cold-rolled dull-finish steel sheet or galvanized steel sheet, each chemically treated with "Palbond #3020" (trade name of a zinc phosphate treating agent; product of Nihon Parkerizing Co., Ltd.) was performed in each of the cationic electrodeposltlon coating compositions obtained in the above-described Examples and Comparative Examples. The resulting test plate was then baked at 170°C for 20 minutes by using an electric hot air drier. The plate thus obtained was tested under the below-described conditions. The results of the test are shown in Table 4.
In the corrosion resistance test (Note 7) using a

galvanized steel sheet, a deterioration in the corrosion resistance is presumed to occur because a stress appears between the separated layers of the film and swelling (in the strain form) tends to be formed easily.
[Table 4]
Table 4: Compositions and test results of cationic

(Note 6) Weatherability: After a test plate (a chemically-treated cold-rolled steel plate) was exposed to a 200-hour accelerated weathering test using a sunshine weatherometer, its gloss retention percentage was studied in

accordance with 60° gloss of JIS K-5400 7.6 (1990).
(Note 7) Corrosion Resistance: Cross-cuts were made with a knife through an electrodeposlted film of each electrodeposited test plate (chemically-treated galvanized steel plate) to a base material. The resulting plat© was subjected to a salt spray exposure test for 840 hours in accordance with JIS Z-2371 and lengths of the rust and blister starting from the knife cut were measured to evaluate corrosion resistance.
(Note 8) Ultrafilterability: A zinc phosphate treating liquid (5000 ppm) was added to a cationic electrodeposition coating through an UF membrane 'NTU-212" (trade name of UF flat membrane; product of Nltto Denko Corporation) for laboratory test. After circulation of the coating by using an apparatus as illustrated in FIG. l, circulation of the cationic electrodeposition coating is stopped, followed by application of a stress on the UF film to test a recovery ratio (permeation amount) of the filtrate after stoppage.
Indicated at numeral 1 in FIG. 1 is a motor for circulating a coating, 2 a container having an UF membrcine placed therein; and 3 a cationic electrodeposition bath. The coating is fed by 4 from this bath and is circulated at 1. The coating circulated at 1 is fed to 2 and separated into a liquid 3 and the coating. The coating thus separated is returned into the cationic electrodeposition bath by 5. The amount of the liquid 3 is measured at 6.
A: a recovering ratio exceeding 85%.

B; a recovering ratio of 75 to 85%.
C; a recovering ratio less than 75%.
(Note 9) Adhesion: A test plate (a chemically treated galvanized steel sheet) was prepared by electrodeposition of each cationic electrodeposition coating thereon, followed by baking to cure. It was allowed to stand for 240 hours in a 50°C blister box. On the resulting plate, a 2 mm Crosshatch pattern was scribed and a peeling test was conducted using a. Cellophane adhesive tape.
A: no problems
B: 95 to 99/100 remained. ,
CJ less than 95/100 remained.
(Note 10) Stability of a coating 1: The remaining amount of the paint after the above-described U/F ability test was measured.
A: less than 10' ml/L
B: 10 to 20 mg/L
C: exceeding 20 mg/L
(Note 11) Stability of a coating 2: After the above-described U/F ability test, electrodeposition was conducted using the cationic electrodeposition coating composition and its coating finish was evaluated.
A: good with no problems.
B: surface roughening and lowering in glaze due to skin absorption are observed.
C; severe surface roughening and lowering in glaze due to sHin absorption.

[Advantageous effects of the Invention]
A cationic electrodeposition coating composition capable of forming a film good in both weatherability and corrosion resistance and being excellent in adhesion and moisture resistance, and moreover, long-terra stability of the coating can be obtained by incorporating therein the cationic resin composition of the present invention comprising an amino-containing epoxy resin (A), an amino-containing acrylic resin (B) and a blocked polyisocyanate curing agent (C) in amounts of 5 to 80 wt%, 5 to 80 wt% and 10 to 40 wt%, respectively, each based on the total weight of the solid content; and having a difference in solubility parameter between the amino-containing epoxy resin (A) and the amino-containing acrylic resin (B) ranging from 0 to 0.7 can provide a film having good weatherability and corrosion resistance.
Since the icind of monomers constituting the resin (B) and their mixing ratio are specified to allow an emulsion containing the resin (B) to have many hydroxyl groups, when a coating containing such a resin (B) is precipitated on the interface of a steel plate, adhesion starts from this point and the coating contributes to an improvement of corrosion resistance.
Furthermore, by specifying the kind of monomers constituting the resin (B) and their mixing ratio, weatherability is improved, because, in an emulsion formed of

shell (base resin) and core (curing agent), an amine-added acrylic resin (B) is formed in the outer layer of the shell and an aniine-added epoxy resin (A) is formed inside of the shell.
A difference in the solubility parameter within a range of from 0 to 0.7 provides the coating with good stability without causing destruction of emulsion particles even if a stress is applied to the coating for a long period of time. [Brief Description of the Drawing]
FIG. 1 illustrates a model of a U/F ability testing apparatus for laboratory use.

WE CLAIM;
1. A cationic electrodeposition coating composition comprising a combination of components A, B and C in amounts of 5 to 80% by wt, 5 to 80% by wt and 10 to 40% by wt respectively based on the total solid content of A, B and C wherein component A is an amino containing epoxy resin such as herein described having an average molecular weight of 500 to 5000; component B is an amino containing acrylic resin such as herein described and component C is a known blocked polyisocyanate curing agent.
2. The cationic electrodeposition coating composition as claimed in claim 1, wherein the amino-containing acrylic resin (B) is obtained by adding an amino-containing compound to a resin obtained by radical copolymerization reaction of a mixture of 5 to 40 wt% of the polylactone-modified hydroxyl-containing radical copolymerizable acrylic monomer, obtained by adding a lactone to hydroxyethyl (meth)acrylate is represented by the formula (1) or (2), 2 to 30 wt% of glycidyl (meth)acrylate and 30 to 93 wt% of another radical copolymerizable monomer, each based on the total solid content of the monomers constituting the amino-containing acrylic resin (B).
3. The cationic electrodeposition coating composition as claimed in claim 1 or 2, wherein the lactone is e-caprolactone.
4. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 3, wherein the amino-containing epoxy resin (A) has an amine value ranging from 40 to 80 mg KOH/g.

5. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 4, wherein the amino-containing epoxy resin (A) has a primary hydroxyl value ranging from 10 to 200 mg KOH/g.
6. The cationic electrodeposition coating composition as claimed in claims 1 to 5, wherein the amino-containing epoxy resin (A) has a number-average molecular weight of from 500 to 5000.
7. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 6, wherein the amino-containing epoxy resin (A) has a solubility parameter 6A of from 9.5 to 11.5.
8. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 7, wherein the amino-containing acrylic resin (B) has a hydroxyl value of from 10 to 300 mg KOH/g.
9. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 8, wherein the amino-containing acrylic resin (B) has an amine value of from 10 to 125 mg KOH/g.
10. The cationic electrodeposition coating composition as claimed in anyone of claims 1 to 9, wherein the amino-containing acrylic resin (B) has a number-average molecular weight of from 10000 to 50000.

Documents:

0111-mas-2003 abstract duplicate.pdf

0111-mas-2003 abstract.pdf

0111-mas-2003 claims duplicate.pdf

0111-mas-2003 claims.pdf

0111-mas-2003 correspondence others.pdf

0111-mas-2003 correspondence po.pdf

0111-mas-2003 description (complete) duplicate.pdf

0111-mas-2003 description (complete).pdf

0111-mas-2003 drawings.pdf

0111-mas-2003 form-1.pdf

0111-mas-2003 form-19.pdf

0111-mas-2003 form-26.pdf

0111-mas-2003 form-3.pdf

0111-mas-2003 form-5.pdf

0111-mas-2003 others.pdf

0111-mas-2003 petition.pdf

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Patent Number

207441

Indian Patent Application Number

111/CHE/2003

PG Journal Number

26/2007

Publication Date

29-Jun-2007

Grant Date

13-Jun-2007

Date of Filing

07-Feb-2003

Name of Patentee

M/S. KANSAI PAINT CO LTD

Applicant Address

33-1 KANZAKI-CHO, AMAGASAKI-SHI, HYOGO-KEN

Inventors:

#	Inventor's Name	Inventor's Address
1	NE	NE

PCT International Classification Number

B32B015/08

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2002-44315	2002-02-21	Japan