Title of Invention

SURFACE TREATED METAL SHEET

Abstract A surface treated metal sheet according to the present invention has a resin coating layer Hereon and the resin coating layer is formed by a composition for forming a resin coating layer, and the composition for forming a resin coating layer includes; 30 to 50 parts by mass of an acrylic urethane-based resin; 50 to 10 parts by mass of silica particles having its mean particle size of 4 to 20 nm, wherein the total amount of the both is 100 parts by mass; and further includes 5 to 25 parts by mass of a silane coupling agent based on the total amount of 100 parts by mass of the acrylic urethane-based resin and the silica particles. By having such a composition, the surface treated metal sheet according to the present invention is excellent in the corrosion resistance, the deep drawing workability, and the coating applicability.
Full Text SURFACE TREATED METAL SHEET
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a surface treated metal sheet excellent in the deep drawing property and in particular, relates to a surface treated metal sheet suitable for deep drawn products used in automobiles, home electric appliances, and building materials, such as audio chassis, computer casings^ motor casings, and pulleys.
2. Description of" the Related Art
[0002] As materials used for parts of home electric appliances, galvanized steel sheets, such as electro-galvanized steel sheets and hot-dip sine-coated steel sheets, and inorganic coating layer treated steel sheets in which a chemical conversion treatment, such as a chromate coating and a phosphate treatment, is performed on the galvanized steel sheet, are widely used to iinprove the corrosion resistance and coating applicability. In addition, a resin coated steel sheet in which an organic resin coating layer is formed on a surface treated steel sheet having a chromate coating provided thereon, has been presented, aiming at further improving the corrosion resistance, the coating applicability, and the workability.
[0003] However, when the deep-drawing processing is performed as in the case of a motor casing in a home electric appliance, there has been a problem as follows: a blackening

phenomenon in which the resin coating layer on the sliding surface peels off and turns black, occurs because intense sliding friction is present between a resin coated steel sheet and a mold at the time of the processing, causing the appearance of the product to be greatly deteriorated, and other defect to occur because the blackening substance generated adheres to the peripheral apparatus.
[0004] Various resin coating layers improved aiming at solving these problems have been presented. Examples of such resin coating layers include, for example, a lubricant coated steel sheet provided with a resin coating layer having an inorganic polymer compound and a solid lubricant, and a lubricant coated steel sheet provided with a resin coating layer having a water-soluble resin in addition to an inorganic polymer compound and a solid lubricant. The coated steel sheet having an inorganic polymer-based coating layer, has an improved scratch resistance and an improved effect for the generation of the blacking substance of its coating layer at the deep drawing processing; however, there have been other problems in that: a coating defect, such as a cissing occurring when applying a solution to the steel sheet, is likely to be present; black dot-shaped rust or white rust is likely to occur because of the high water permeability of the coating layer; and the adhesion property of the coating layer is deteriorated when applied.
[0005] In addition, with the increasing awareness for the environment, steel sheets without using hexavalent chrome have

recently been widely used, instead of chromate coating conventionally used for the purpose of improving corrosion resistance of zinc plated steel sheets. Therefore, there is a demand for a new coating layer more excellent in the corrosion resistance, to be developed.
[0005] As a resin coating layer aiming at more improved corrosion resistance, a surface treated metal sheet having a carboxylic group-containing polyurethane resin, or having a mixture of a carboxyl group-containing polyurethane resin and an ethylene-unsaturated carboxylic acid copolymer (JP-A-20 05-200757, JP-A-2006-42913).
[0007] However, in recent years, electric appliances have been further developed in its performance and miniaturization, and with the accuracy of dimensions of processed products being more strictly requested, the processing conditions of steel sheets are becoming more strict. In particular, when the deep drawing processing is performed, there are sometimes the cases where a molding apparatus with a clearance narrower than a sheet thickness of a steel sheet to be processed, is used in order to enhance the accuracy of the dimension. In the cases, intense sliding friction occurs more than ever between the resin coating layer and the moid, causing the problem in that the appearance of the sliding surface is deteriorated to be revealed. Because such a problem similarly occurs with a steel sheet having a conventional coating layer, there is an increasing demand for improving the appearance of a processed product more than ever.

SUMMARY OF THE INVENTION
[0008] The present invention has been made in view of these
circumstances, and an object of the invention is to provide a
surface treated metal sheet which is improved in the corrosion
resistance, the coating applicability, and the deep drawing
workability.
To address the above problems, a surface treated metal sheet according to a primary aspect of the present invention, has a resin coating layer thereon, and the resin coating layer is formed from a resin composition for forming a coating layer, the resin composition for forming a coating layer including: 30 to 50 parts by mass of an acrylic urethane-based resin; 50 to 70 parts by mass of silica particles having its mean particle size of 4 to 20 nm, wherein the total amount of the both is 100 parts by mass; and further includes 5 to 25 parts by mass of a silane coupling agent based on the total amount of 100 parts by mass of the acrylic urethane-based resin and the silica particles. [0009] The acrylic urethane-based resin preferably includes: a polyurethane obtained from a urethane prepolymer which contains, as raw materials, polyisocyanate, polyol, and dihydroxyalkanoic acid, and is synthesiaed from the total amount of 3 to 80 parts by mass of the three; and a (metha) acrylic-based polymer obtained from 10 to 97 parts by mass of a (metha) acrylic monomer. Further, the acrylic urethane-based resin preferably has at least either a carbonyl group or a hydrazine group in at

least either structure of the polyurethane and the [metha)
acrylic-based polymer. Still further, the resin cpating layer
preferably has an azomethine cross-linked structure.
[0010] The acrylic urethane-based resin preferably has a
softening point of 120°C or more and a Sward rocker hardness of
25 or more.
[0011] The silane coupling agent preferably has a structure
represented by the following formula (1);
[Formula 1]
R^-X-Si-R^ (1)
R^ ,rc.r, epoacy-cy do >^e;.c/ ftcvf
(wherein R represents a glycidoxy group, R and R^, lower alkoxy
A
groups, respectively, R^, a lower alkoxy group or a lower alkyl
group, and X, a lower alkylene group.)
[0012] In addition, an adhesion amount of the resin coating layer on the metal sheet is preferably 0.05 to 1 g/m". [0013] The surface treated metal sheet according to the present invention is excellent in the corrosion resistance, the deep drawing workability, and the coating applicability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Embodiment(si of the present invention will be described in detail based on the following figures, wherein:
Fig. 1 is a drawing showing a processing device used for the evaluation for the deep drawing workability; and

Fig.2 is a drawing showing an external appearance of a sliding portion of a steel sheet after being subjected to the deep-drawing processing.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The surface treated metal sheet according to the present invention has a resin coating layer thereon, and the resin
coating layer is formed from a composition for forming a resin coating layer, the composition for forming a resin coating layer including: 30 to 50 parts by mass of an acrylic urethane-based resin; 50 to 70 parts by mass of silica particles having its mean particle size of 4 to 20 nm; and 5 to 25 parts by mass of a silane coupling agent based on the total amount of 100 parts by mass of the acrylic iirethane-based resin and the silica particles. The present invention will be described in detail below. (1) Resin Composition fot Forming Coating Layer (1-1) Acrylic Urethane-based Resin
[0016] An acrylic urethane-based resin used in the present invention includes a (metha) acrylic-based polymer and a polyurethane. A reason why a (metha) acrylic-based polymer and a polyurethane are used together in this way, is; when a resin component is to be solely a (metha) acrylic-based polymer, the resin is deteriorated in the flexibility while the workability (the blackening resistance) being secured, because the resin coating layer is increased in its hardness, causing a crack to easily occur in the resin coating layer, thereby the corrosion

resistance being easily deteriorated. Hence, a polyurethane, which allows a resultant resin coating layer to be provided with the flexibility, to be excellent in the chemical resistance and the wear resistance, and further to be provided with the strength, is used along with a (metha) acrylic-based polymer, allowing the resin coating layer (surface treated metal sheet) to be provided with the workability as well as the flexibility. [0017] An object of the present invention is to provide a surface treated metal sheet in which an appearance problem, such as a blackening phenomenon, hardly occurs, even when a severe processing condition is adopted in which a mold with a clearance narrower than the sheet thickness of a steel sheet to be processed, is used. When a severe processing condition as mentioned above is adopted, a big power is applied to the steel sheet momentarily. At the time, the resin coating layer formed on the metal surface is required to have the flexibility possible to follow the deformation of the steel sheet, as well as the hardness possible to endure the impact occurring when contacting the molding equipment. Therefore, the present invention adopts an acrylic urethane-based resin having the above composition, in order to provide a surface treated metal sheet having the both properties. [0018] Examples of (metha) acrylic-based monomer components constituting the above (metha) acrylic-based polymer include: a monomer having a carboxyl group, such as (metha) acrylic acid, itaconic acid, and crotonic acid; a monomer having a hydroxy group, such as 2-hydroxy (metha) ethyl acrylate, 2-hydroxy (metha)

propyl acrylate, and 4-hydroxy (metha) butyl acrylate; and
(metha) acrylic ester.
[0019] Examples of acrylic esters include: methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isobornyl acrylate, N,N-dimethylaminoethyl acrylate, isobutyl acrylate, 2-methoxyethyl acrylate, 3-methoxybutyl acrylate, lauryl acrylate, n-stearyl acrylate, tetrahydrofurfuryl acrylate, trimethylolpropane acrylate, and 1,9-nonanediol acrylate. Examples of ester methacrylates include: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t~butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, alkyl methacrylate, tridecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, allyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1, 3-butylene glycol dimethacrylate, 1, 6-hexandiol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolpropane trimethacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, trifluoroethyl methacrylate, heptadecafluorodecyl methacrylate. One or more types of these (metha) acrylate monomer components can be selected for use, as necessary.
[0020] Among the above (metha) acrylic-based monomer

components, butyl acrylate and n-butyl methacrylate are particularly desirable.
[0021] A polyurethane directed to the present invention is preferably obtained by polymerizing polyisocyanate, polyol, and hydroxyalkanoic acid, and more preferably obtained by Synthesizing urethane prepolymer from polyisocyanate, polyol, and hydroxyalkanoic acid, and subsequently by subjecting the Urethane prepolymer to a chain-growth reaction. [0022] As for a polyisocyanate component constituting the above urethane prepolymer, a component having two or inore isocyanate groups in a single molecule is desirable. Specifically, polymers can be cited as follows: yellowing type polyisocyanates, such as 4, -3'-diphenylmethane diisocyanate, 2, 4'-diphenylmethane diisocyatiate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, 4, 4-toluene diisocyanate, 1, ^-naphthalene diisocyanate, l, 5-naphthalene diisocyanate, 1, 2-phenylene diisocyanate, 1, 3-phenylene diisocyanate, and 1, 4-phenylene diisocyanate; hardly yellowing type polyisocyanates, such as o-xylylene diisocyanate, p-xylylene diisocyanate, and ni~xylylene diisocyanate; non-yellowing type polyisocyanates, such as 4, 4 '-dicyclolmethane diisocyanate, 2, 4 '-dicyclomethane diisocyanate, 2, 2 ' -dicycloitiethane diisocyanate, hexam^ thy lane diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, and lysine diisocyanate; crude toluene diisocyanates; and polyphenylene polymethylene isocyanates. These polyisocyanates may bs used alone or in combination as a

mixture of two or more of them. Among the above polyisocyanates, the non-yellowing type polyisocyanates are most desirable from a point of view of keeping the appearance of a metal sheet in a good condition.
[0023] As a polyol component constituting the urethane prepolymer, a polyol having two or more hydroxyl groups in a single molecule is desirable, and either a low-molecular weight type or a high-molecular weight type may be used. As low-molecular weight types, ethylene glycol, diethylene glycol, trimethylene glycol, triethylene glycol, propylene glycol, butylene glycol, hexaraethylene glycol, neopentyl glycol, 1, 4-cyclohexane dimethanol, sorbitol, pentaerythritol, glycerin, trimethylolpropane, trimethylolethane, etc., can be cited. Among those, trimethylolpropane and 1, 4-cyclohexane dimethanol are desirable. As high-molecular weight types, polyether polyol, polyester polyol, epoxy polyol, silicon polyol, etc., can be cited.
[0024] As the above polyether polyols, a product obtained by polymerization of a cyclic oxide, such as ethylene oxide, propylene oxide, or tetrahydrofran; or a product obtained by adding one or more of cyclic oxides into water, ethylene glycol, propylene glycol, diethylene glycol, cyclohexane dimethanol, glycerin, trimethylolpropane, pentaerythritol, or bisphenol A, can be cited, for example.
[0025] As polyester polyols, a product obtained by polymerization of a diol with a dibasic acid can be cited, in which:

as a diol component, ethylene glycol, diethylene glycol, 1, 4-butanediol, neopentyl glycol, 1, 6-hexandiol, 1, 5-inethyl pentanediol, 1, 4-cyclohexane dimethanol, etc., can be cited; and as a dibasic acid, adipic acid, isophthalic acid, terephthalic acid, azelaic acid, sebacic acid, other dimer acid, etc., can be cited. The above "dimer acid" refers to a product obtained by dimerizing unsaturated long-chain aliphatic monocarbosylic acids having 13 to 22 carbon atoms, or dimerizing esters thereof. Specific examples of the dimer acids include: a dimer acid having 36 to 44 carbon atoms derived from an unsaturated carboxylic acid having 18 to 22 carbon atoms; a dimer acid derived from an unsaturated fatty acid having 18 carbon atoms which contains an acid, such as linoleic acid, and linolenic acid; or the like. Among those polyester polyols, a polyester polyol containing a dimer acid is desirable.
[0026] As dihydroxyalkanoic acids constituting the above urethane prepolymer, 2, 2-dimethylol acetic acid, 2, 2-diitiethylol propionic acid, 2, 2-dimethylol butyric acid, dimethylol butanoic acid, etc./ can be cited: Among them, dimethylol propionic acid and dimethylol butanoic acid are desirable from points of view of the reactivity and the solubility, etc.
[0027] A resin coating layer formed on the surface treated
metal sheet according to the present invention has preferably an
azomethine cross-linked structure. An azomethine cross-linked
structure means a structure represented by the following formula
(2) , and is formed by a reaction of an organic hydrazine compound

with a ketone-based or aldehyde-based carbonyl compound: [Formula 2]
C=N- (2)
/
[0028] With an azomethine cross-linked structure formed in the resin coating layer, the fastness to the reciprocating friction by a cloth impregnated with ethanol is improved, and the Konig hardness and the 100% modulus (tensile stress at 100% elongation) are enhanced, allowing many physical properties of the surface treated metal sheet to be improved. In addition, because the reaction between the above organic hydrazine compound and the carbonyl compound proceeds with removal (volatilization) of the water in the coating layer and an alkali component used for neutralization of the resin, the reaction proceeds independently of the ambient temperature, as long as they are held under a condition where such a situation is established. Therefore, a particular operation for the cross-linking reaction is not required to be performed. Moreover, the reaction is self-cross-linkable, therefore, no cross-linking agent, such as formaldehyde, is required to be added.
[0029] As embodiinents of the acrylic urethane-based resin capable of forming the above azomethine cross-linkage, the following embodiments 1 to 3 can be cited: [0030] embodiment 1: the acrylic urethane-based resin includes at least one of polyurethanes having a hydrazine group.

and at least one of (metha) acrylic-based polymers having a carbonyl group;
[0031] embodiment 2: the acrylic urethane-based resin includes at least one of polyurethanes and at least one of (metha) acrylic-based polymers, and each of which having a carbonyl group and at least two of hydrazine groups, respectively; and [0032] embodiment 3: the acrylic urethane-based resin includes at least one of polyurethanes and at least one of (metha) acrylic-based polymers / and each of which having a hydrazine group and at least two of carbonyl groups, respectively. [0033] Introduction of a hydrazine group into a polyurethane may be performed by using a chain extender having a hydrazine compound or a hydrazine group, which can react with an isocyanate group, such as hydroxyl group, at the time of synthesizing the urethane prepolymer, or subjecting the urethane prepolymer to a chain extension reaction. At the time, the hydrazine group is necessary to be blocked by a mono-aldehyde or a mono-ketone to prevent it from reacting. As such hydrazine compounds, 7-hydroxy butyl hydrazide of which hydrazine group is blocked by a mono-aldehyde or a mono-ketone; and semi-carbazide ethyl methacrylate of which hydrazine group is blocked by ketone/aldehyde having boiling points of 30 to 200°C, and is reacted with ethanol amine; or the like, can be cited. The above hydrazine compounds can be prepared by reacting a reaction product between a diamine and 0.2 to 2 mole of a (metha)acrylic acid derivative (preferably ethyl acrylate), with a hydrazine. The

mono-aldehyde and the mono-ketone used for blocking a hydrazine group are desorbed from the hydrazine group by the inside resin coating layer being acidified due to the removal of the alkaline component used for water dispersion of the resin composition, at the time of drying the resin coating layer formed from the coating-layer-forming resin composition containing the acrylic urethane-based resin. As a result, a hydrazine group is generated and subsequently the azomethine cross-linking reaction originates.
[0034] As a diamine described above, aliphatic diamines having 2 to 15 carbon atoms, and alicyclic and aromatic diamines having 6 to 15 carbon atoms, can be cited; and specific examples thereof include ethylenediamine, 1, 4-butandiamine, 1/ 6-hexanedimaine, 2-methyl-l, 5-pentandiamine, 2, 2, 2-trimethyl-l, 6-hexanedimaine, 2, 2, 4- and 2, 4, 4-trimethyl-l, 6-hexanediamine, bis(4-aminocyclohexyl) methane, and di (aminomethyl) benzene, etc.
[0035] When a polyurethane having a hydrazine group is adopted, an amount of the hydrazine group is preferably 2 to 500 milliequivalents in 100 g of the polyurethane, more preferably 20 to 200 milliequivalents, still preferably 50 to 115 milliequivalents. Therefore, an amount of use of the above hydrazine compound should be determined as follows: a functional group in the above hydrazine compound, which is reactive with the isocyanate group contained in the polyisocyanate constituting the polyurethane, is preferably 100 to 1000 milliequivalents based

on one equivalent of the isocyanate group, more preferably 3O0 to 800 milliequivalents, still more preferably 450 to 600 mi Hi equivalents.
[0036] Introduction of a carbonyl group into the polyurethane may be performed by using a carbonyl compound having one, or preferably two or more functional groups which are reactive with the isocyanate group, at the time of synthesizing the urethane prepolymer or subjecting the urethane prepolymer to the chain extension reaction. As such carbonyl compounds, dihydroxyketone, such as dihydroxyacetone; a product obtained by the Michael Addition Reaction between diacetone acrylamide and diamine or alkanolamine; or the like, can be cited. Example of the carbonyl compound usable at the time of the chain extension reaction, includes a product of the Michael Addition Reaction between 2 moles of diacetone acrylamide and Imol of diamine. [0037] When a polyurethane having a carbonyl group is used, an amount of the carbonyl group in 100 g of the polyurethane, is preferably 2 to 230 milliequivalents, more preferably 5 to 180 milliequivalents, still more preferably 10 to 55 milliequivalents. Therefore, when a polyurethane having a carbonyl group is used, an amount of use of the carbonyl compound should be determined as follows: an amount of a functional group contained in the carbonyl compound , which is reactive with an isocyanate group contained in a polyisocyarate constituting the polyurethane, is 8 to 880 milliequivalents based on one equivalent of the isocyanate group, more preferably 19 to 690 milliequivalents.

still more preferably 38 to 211 milliequivalents.
[0038] On the other hand, a (metha) acrylic-based polymer having a hydrazine group can be obtained by polymerizing a monomer component having a functional group capable of generating a hydrazine group by reacting with hydrazine or hydrazine monohydrate. Specific examples of monomer components include crotonic acid, a-chloro acrylate, (metha) acrylate, acid chloride, or their esters; and in particular, a (metha) acrylic ester of a low-molecular weight alcohol is preferably used. As (metha) acrylic esterc of a low-molecular weight alcohol, (metha) methyl acrylate ester, (metha) ethyl acrylate ester, (metha) acrylic acid propyl ester, (metha) acrylic acid isopropyl ester, (metha) acrylic acid n-butyl ester, etc., can be cited. In addition, as copolymerization component, vinyl halides, such as vinyl chloride, vinyl fluoride, and vinylidene chloride; vinyl aryl compounds, such as styrene, and substituted styrene; butadiene; and 2-chlorobutadiene, may be used.
[0039] A (metha) acrylic-based polymer having a hydrazine group can be obtained by reacting a homopolymer or a copolymer, which is obtained by polymerizing the above monomer component, with hydrazine or hydrazine monohydrate. A functional group which can be converted to a hydrazine group, is preferably present in an amount of 5 to 300 milliequivalents in 100 g of a
(metha) acrylic-based poli-Tner, more preferably 10 to 200 milliequivalents, still more preferably 20 to 150 milliequivalents . The above hydrazine or hydrazine monohydrates

is preferably used in an amount of 5 to 300 milliequivalents based on 100 g of the (metha) acrylic-based polymer, more preferably 10 to 200 milliequivalents.
[0040] When the polyurethane is produced after synthesizing the (metha)acrylic-based polymer (the chain extension reaction of the urethane prepolymer is performed), a hydrazine group introduced into the acrylic-based polymer is preferably to be blocked with a mono-aldehyde or mono-ketone.
[0041] Introduction of a carbonyl group into the (metha) acrylic-based polymer may be performed by using a monomer containing a carbonyl group as a (metha) acrylic-based monomer component. Examples of such carbonyl group-containing monomers include: acrolein, methacrolein, diacetone aery1amide, acrylamide pivalaldehyde, methacrylamide pivalaldehyde, diacetone acrylate, or the like.
[0042] When a poly (metha)acrylic-based polymer having a carbonyl group is used, the carbonyl group is preferably used in an amount of 2 to 230 milliequivalents in 100 g of the poly (metha) acrylic-based polymer, more preferably 5 to 180 milliequivalents, still more preferably 10 to 55 milliequivalents. [0043] As a compound having two hydrazine groups used in the embodiment 2, dicarboxylic acid dihydrazide can be cited; and specific examples thereof include oxalic acid dihydrazide, malonic acid dihydrazide- succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, etc. As compounds having two carbonyl groups used in the embodiment 3, di- or

polyketone, or polyaldehyde, such as glyoxal, 2, 5--hexanedione, glutaric dialdehyde, succinic acid dialdehyde, can be exemplified.
[0044] When using a polyurethane having a hydrazine group, and a poly (raetha) acrylic-based polymer having a carbonyl group (the embodiment 1) , a mixing amount of the two is determined such that: the carbonyl group is preferably 0.02 to 1.6 equivalents based on one equivalents of the hydrazine group present in the polyurethane, more preferably 0.05 to 0.9 equivalents. [0045] When using a compound having the above two hydrazine groups [namely, the embodiment 2) , the compound is preferably used-in an amount of 0.02 to 1.6 equivalents based on one equivalent of the carbonyl group derived from the polyurethane in the acrylic urethane-based resin and/or derived from the (metha) acrylic-based polymer, more preferably 0.05 to 0.9 equivalents. [0046] On the other hand, when using a compound having the above two carbonyl groups (the embodiment 3), the compound is preferably used in an amount of 0.02 to 1.6 equivalents based on one equivalent of the hydrazine group derived from the polyurethane present in the acrylic urethane-based resin and/or derived from the (metha)acrylic-based polymer, more preferably 0.05 to 0.9 equivalents.
[0047] In the present invention, the acrylic urethane-based resin is, after a polyurethane or an urethane prepolymer is synthesized, preferably obtained by polymerizing the (metha) acrylic-based monomer in the presence of the polyurethane or the

urethane prepolymer, in the same system as that in which the polyurethane (or the urethane prepolymer) has been produced, while the acrylic urethane-based resin may be obtained by mixing a (metha)acrylic-based polymer component and a polyurethane component, which have been synthesized separately. With a polyurethane and a (metha) acrylic-based polymer synthesized in the same system, the polyurethane and the (metha) acrylic-based polymer can be kept in a more uniformly mixed state in the acrylic urethane-based resin.
[0048] Hence, a method for producing the acrylic urethane-based resin directed to the present invention, is not particularly limited, as long as an acrylic component is polymerized in the same system as that in which an urethane component has been synthesized; therefore, a conventional method can be adopted. As described later, since the acrylic urethane-based resin directed to the present invention is used as an aqueous dispersion solution, it is desirable that the resin is made to an aqueous dispersion solution at the stage when the resin is produced. For example, a method in which a (metha) acrylic-based monomer is polymerized following the production of an urethane prepolymer, and subsequently the resultant acrylic urethane-based resin is dispersed in water; another method in which an urethane prepolymer is produced to be dispersed in water, and subsequently a (metha) acrylic-based monomer component is polymerized; or the like, can be cited. In addition, a (metha) acrylic-based monomer can also be used as a solvent in

synthesizing the urethane prepolymer, when the (metha) acrylic-based monomer is added in the system in which the urethane prepolymer is synthesized, along with a polymerization-inhibitor, In this case, the (metha) acrylic-basedmonomer may be polymerized by adding a radical polymerization initiator, after synthesizing the urethane prepolymer.
[0049] In synthesizing the urethane prepolymer, a mixture ratio of a polyisocyanate to a polyol is preferably 1.0 to 2.0 as a ratio of NCO/OH, more preferably 1.2 to 1.9, still more preferably 1.3 to 1.7.
[0050] In addition, the hydroxyalkanoic acid is preferably used in such an amount that an acid value of the urethane prepolymer is 20 to 80 mg KOH/g, based on the polyisocyanate and the polyol. [0O51] A temperature at which the urethane prepolymer is synthesized is not particularly limited, but is preferable 60 to gS^C. In addition, a polymerization catalyst may be used in synthesizing the urethane prepolymer, as necessary. Examples of polymerization catalysts include an organic compound, such as tin (11) salt of carboxylic acid; and strong bases, such as tertiary amine, alkali metal hydroxide, alcoholate, and phenolate. Specifically, di-n-octyl mercaptide, dibutyltin maleate, dibutyltin diacetate, and dibutyltin dilaurate can be cited. [0052] A weight average molecular weight of the urethane prepolymer is preferably 400 to 10,000, more preferably 3,000 to 9,000, still more preferably 4,000 to 8,000. The above weight average molecular weight is a value measured by using a gel

permeation chromatography (GPC) (indicated as an equivalent value of polystyrene).
The polyurethane component according to the present invention is preferably obtained by extending the urethane prepolymer with a chain extender. The chain extension reaction may be performed before or after the water dispersion, or simultaneously with it.
[0053] Examples of chain extenders include: ethylene diamine, diethylene triamine, triethylenetetramine, propylene diamine, butylenes diamine, hexamethylene diamine, cyclohexylene diamine, piperazine, 2-methyl piperazine, phenylenediamine, tolylenediamine, xylylenediamine, tris (2-aminoethyl) amine, 3, 3'-dinitro benzine, 4, 4'-diaminophenylmethane, menthanediamine, m-xylenediamine, isophoronediamine, isophoronediamine, hydrazine derivative, or water; and among these, a hydrazine derivative is most desirable. Examples of hydrazine derivatives include, for example: hydrazine; hydrazine monohydrate; monosubstituted hydrazine, such as methyl hydrazine, ethyl hydrazine; hydroxyalkyl substituted hydrazine, such as 2-hydroxyethylhydrazine, 2-hydroxypropylhydrazine; alkylene hydrazine, such as methylenedihydrazine, ethylenedihydrazine, and propylenedihydrazine; dihydrazide, such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, aliphatic dicarboxylic acid hydrazide, unsaturated

aliphatic dicarboxylic acid hydrazide, aromatic dicarboxylic acid hydrazide, maleic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, and carbo dihydrazide . Among these, the hydrazine monohydrate is preferably used. [0054] The above chain extender is preferably used in an amount of 0.3 to 1.7 equivalents based on one equivalent of NCO group in the urethane prepolymer, more preferably 0.5 to 1.5 equivalents, still more preferably 0.8 to 1.2 equivalents. [0055] The above urethane prepolymer or polyurethane can be emulsified and dispersed in water by neutralizing with a base. When a (metha) acrylic-based polymer [described in detail later) containing a carboxyl group or an alkyl ester of a carboxyl group is present in the system at the time, a carboxyl group derived from the (metha) acrylic-based polymer is also neutralized as well as the urethane prepolymer or the polyurethane. Examples of neutralizing agents usable in this case include: alkali metal hydrides, such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; ammonia; tertiary amines, such as triethylamine, N,N-dirciethylbutylamine, N,N-dimethylallylamine, N-methylpyrrolidine, tetramethyIdiaminomethan, and trimethylamine; secondary amines, such as N-methylethylamine, diisopropylamine, and diethylaraine; primary amines, such as propylamine, t-butylamine, sec-butylamine, isobutylamine, 1,2-dibutylpropylamine, and 3-pentylamine; morpholine-based compounds, such as morpholine, N-methylmorpholine, and N-ethylmorpholine; piperazine-based compounds, such as

piperazine, hydroxyethylpiperazine, 2-niethylpiperazine, and aminoethylpiperazine; aminoalcohols, such as N,N-diethylethanolamine, N,N-dibutylethanolamina, N- {|3-aminoethyl) ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethy1ethanolamine, N-n-butylethanolamine, N-n-butyldiethanolamine, N-t-butylethanolamine, N-t-butyldiethanolamine, N- (p-aminoethyl)isopropanolamine, N,N-diethylisopropanolamine, and 2-amino-2-methyl-l-propanol; diamines, such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylethanolamine, 1,6-hexamethylenediamine, methaxylylenediamine, 1,2-diaminopropane, and
1, 4-diaminobutane; aliphatic amines, such as coconut amine, octyl amine, lauryl amine, stearyl amine, and oleyl amine; and EO adducts thereof, fimong them, ammonia and triethylamine are desirable because they evaporate during formation of the resin coating layer, hence there is no fear that a neutralizing agent may remain therewithin, and triethylamine is more desirable. [0056] When the above (metha) acrylic-based monomer and the polymerization initiator will be added in the system where the urethane prepolymer are synthesized, or where the chain extension reaction of the urethane prepolymer is completed, and when the (metha) acrylic-based monomer has been used as a reaction solvent, the (metha) acrylic-based monomer is polymerized by adding the polymerization initiator after the urethane prepolymer is

synthesized , or after the chain extension reaction of the urethane prepolymer is completed.
[0057] The (metha) acrylic-based monomer is preferably used in an amount of 10 to 97 parts by mass based on the total amount of 3 to 80 parts by mass of polyisocyanate, polyol, and hydroxyalkanoic acid, which are components constituting the urethane prepolymer. In the case, a ratio of use of the urethane prepolymer to the (metha) acrylic-based monomer vary depending on a glass transition temperature of the resultant (metha) acrylic-based polymer. Assuming that the total of the urethane prepolymer and the (metha)acrylic-based monomer is 100 parts by mass, the acrylic-based monomer is preferably used in an amount of 50 to 97 parts by mass based on 3 to 50 parts by mass of the urethane prepolymer components, more preferably 50 to 97 parts by mass based on 3 to 40 parts by mass of the urethane prepolymer components. The glass transition temperature of the (metha) acrylic-based polymer calculated from the Fox equation, is
preferably -30 to 90 "C, more preferably-20 to eO°C. An acid value of the (metha) acrylic-based polymer directed to the present invention is preferably 0 to 400 mg KOH/g. [0058] Examples of the polymerization initiators at polymerizing the (metha) acrylic-based monomer include: azo compounds, such as azobisisobutyronitrile and its chloride salt, and 4,4'-azobis (4-cyanovaleric acid); and peroxides, such as organic peroxides including benzoyl peroxide, dicumyl peroxide, lauroyl peroxide, and cumene hydroperoxide, and inorganic

peroxides including potassium persulfate, sodium persulfate, ammonium persulfate, perborate salt, and persuccinate salt. [0O59] The polymerization initiator is preferably used in an amount of 0.05 to 3 parts by mass based on the total mass of the (metha) acrylic-based monomer. The temperature at polymerization of the (metha) acrylic-based monomer is not limited to, but preferably 30 to 3 00°C, more preferably 50 to 7 0'C. [0060] The (metha) acrylic-based monomer may be emulsified prior to the polymerization reaction thereof, for example, simultaneously with the emulsif ication of the urethane prepolymer, or at the time of the chain extension thereof; and the monomer is preferably emulsified simultaneously with the emulsif ication of the urethane prepolymer.
[0061] In synthesizing an acrylic urethane-based resin according to the present invention (synthesis of the urethane prepolymer, chain extension reaction thereof, and polymerization reaction of the (metha)acrylic-based polymer), a known organic solvent can be used. Examples of organic solvents include: aromatic solvents, such as toluene and xylene; ester-based solvents, such as methyl acetate, and ethyl acetate; ketone-based solvents, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; glycol ether ester-based solvents, such as ethylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate; alcohol-based solvents, such as methanol, ethanol, and isopropanol; dimethylformamide; dimethylacetoamide; and N-methyl pyrrolidone. These organic

solvents may be used alone or in combination of a mixture of two or more of them. In addition, the (metha) acrylic monomer component may also be used as a solvent when polymerizing the urethane component. In the case, any conventionally known polymerization inhibitor may be usable; and the methoxyphenol is desirable.
[0062] In the present invention, the acrylic urethane-based resin is preferably a self-dispersion type resin that is readily dispersed in water or an aqueous solvent in which water is a main component {50 mass % or more). However, when the acrylic urethane-based resin is difficult to disperse in water or an aqueous solvent, a resultant emulsion generated by dispersing the resin mechanically, sometimes has an increased particle size and a deteriorated storage stability. Hence, a surfactant maybe used as necessary, in such a case.
[0063] As a surfactant, conventionally known surfactants may be used, such surfactants including nonionic, anionic, and cationic surfactants; however, it is desirable to select a type and a use amount thereof depending on the purpose, such that the effect of the present invention should not be interfered with its expression. Examples of nonionic surfactants include: polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene dodecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene isostearyl ether, polyoxyethylene behenyl ether, polyoxyethylene-2-ethyl-hexyl

ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ether (synthesis), narrow type polyoxyethylene alkyl ether, polyoxyethylene octyldodecyl (gelbe type) ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene p-naphtyl ether, polyoxyethylene hardened castor oil ether, polyethylene glycol monoalkyl fatty acid ester, polyethylene glycol dialkyl fatty acid ester, polyoxyethylene sorbitan monolaurate ester.
[0064] In addition, a suitable aqueous dispersion solution sometimes cannot be obtained by using only a nonionic surfactant, therefore it is desirable to use an anionic surfactant or a reactive surfactant in combination. Examples of anionic surfactants include: semi-hardened beef tallow fatty acid soap Na salt, stearic acid soap Na salt, oleic acid soap K salt, gum rosin-based disproportionation rosin sodium salt, alkenylsuccinate dipotassium salt, dodecyl sulfate ester Na salt, polyoxyethylene alkyl (C12, C13) ether sulfate ester Na salt, polyoxyethylene dodecyl sulfate ester ammoniuia salt, dodecylbenzene sulfate Na salt. Examples of cationic surfactants include: higher alkyl monoamine salt, dialkylethyl methylethyl ammonium sulfate salt.
[0065] Examples of reactive surfactants include: polyoxyethylene alkyl phenyl ether and sulfate ester salt thereof, sulfosuccinate type, alkenyl polyoxyalkylene phosphoric ester, polyoxyethylene alkyl phosphoric ammonium glycidyl ether addition. A protective colloid, such as polyvinyl alcohol, may

be used instead of a surfactant.
[0066] Specific methods for making an aqueous dispersion
solution include, for example: a method for making an aqueous dispersion solution of polyiaer by adding a surfactant, a polymerization catalyst, and water, into the prepolymer Containing the (metha) acrylic-based monomer, after the prepolymer has been neutralized with amine; and another method for making an aqueous dispersion solution of polymer by performing a pol^TTierization reaction with the prepolymer containing the (metha] acrylic-based monomer, which has been neutralised with amine, and a polymerization catalyst, adding into an aqueous solution made of a surfactant and water. In either case, the surfactant is preferably used in an amount of 0 to 30 mass % based on the total mass of the (metha) acrylic-based monomer. In addition, the prepolymer containing the (metha) acrylic-based monomer may be emulsified after a neutralizing agent (amine) has been mixed with water.
(l-2)Mixing Amount of Acrylic Urethane-Based Resin [0067] A resin composition for forming a coating layer used in the present invention, is characterized in that the resin composition includes: 30 to 50 parts by mass of an acrylic urethane-based resin; 50 to 70 parts by mass of silica particles having its mean particle size of 4 to 20 nm, wherein the total amount of the both is 100 pairts by mass; and further includes 5 to 25 parts by mass of a silane coupling agent based on the total amount of the above 100 parts by mass. When using an aqueous

dispersion solution of acrylic urethane-based resin, an amount of a non-volatile resin component in the aqueous dispersion solution of acrylic urethane-based resin is preferably 30 to 50 parts by mass.
[0068] When an amount of the acrylic urethane-based resin component is too small, the resin coating layer tends to be deteriorated in the corrosion resistance and the coating applicability. On the other hand, when an amount of the acrylic urethane-based resin component is too large, the rein coating layer tends to be deteriorated in the blackening resistance. From such a point of view, the acrylic urethane-based resin is used in an amount of 30 parts by mass or more, more preferably 35 parts by mass or more, and 40 parts by mass or less. Herein, it is noted that the non-volatile resin component in the aqueous dispersion solution of acrylic urethane-based resin is the above acrylic urethane-based resin; and the non-volatile resin component can be measured by using a method known in the art concerning aqueous dispersion solutions, and is, for example, the evaporation residue when heating the aqueous dispersion solution
to 100 to 130°C for 1 to 3 hours.
[0069] The deteriorated blackening resistance is considered to be caused by that: in the harsh deep-drawing processing of, for example, a casing of a motor, the coating layer formed on the resin coated metal sheet is shaved and peeled off, and the resin component in the coating layer is softened then adhere to the sliding surface of a product to blacken there, because of the mold

sliding and frictional heat generated by the slide between the mold and the metal sheet, during the processing. The blackening phenomenon is generated in the way as follow; a peeled coating layer (resin component}, zinc powder partially peeled from the zinc plated layer, and the press oil, are intermingled and mixed together to make a blackened material; the blackened material adheres to the mold; and the adhered blackened material is transferred to the surface of a product to generate the blackening phenomenon. [0070] In general, it is estimated that the mold is heated
to about 120°C during the press processing; therefore, when a softening point (softening temperature) of the resin component contained in the peeling coating layer, is 120°C or less, the blackening phenomenon appears more apparently. [0071] Hence, an acrylic urethane-based resin having its
softening point of 120°C or more, is desirable for the use in the resin composition for forming the coating layer according to the present invention.
[0072] In addition, in order to reduce the blackening phenomena, it is needed that a peeling amount of the coating layer is reduced and the adhesion thereof to a product is inhibited. Therefore, the acrylic urethane-based resin preferably has its Sward rocker hardness (SW hardness) of 25 or more, as a film property thereof. That is, the hardness of the coating layer formed on the metal sheet is improved by hardening the acrylic

urethane-based resin, thereby the coating layer is less damaged by the mold sliding; and the peeled coating layer is hardened itself, thereby the peeled coating layer less adheres to the mold and is less transferred to a product.
[0073] From such a point of view, the acrylic urethane-based resin preferably has its softening point of 120°C or more and Sward rocker hardness of 25 or more. (1-3) Silica Particle
[0O74] The resin composition for forming a coating layer used in the present invention includes silica particles in an amount of 50 parts by mass or more, preferably 60 parts by mass or more, and 70 parts by mass or less, preferably 65 parts by mass or less, based on the 30 to 50 parts by mass of the acrylic urethane-based resin (wherein, the total amount of the acrylic urethane-based resin and the silica particles is 100 parts by mass). [0075] The silica particles not only provide the resultant resin coating layer with the corrosion resistance and the coating applicability, but also enhance the hardness of the coating layer, allowing the deep drawing workability to be improved. When a content of the silica particles is 50 parts by mass or less, the deep drawing workability tends to be deteriorated. On the other hand, when a content of the silica exceeds 70 parts by mass, the formability of the resin coating layer is deteriorated, and the corrosion resistance thereof tends to be decreased. [0075] In order to exert the effects by the silica particles to a maximum degree, a mean particle size of the silica particles

is preferably 4 to 20 nm. As a mean particle size of the silica particles is smaller, the resin coating layer is improved in the corrosion resistance; however, when a mean particle size thereof is below 4 nrti, the effect of improving the corrosion resistance tends to be saturated, and the aqueous solution in which the resin is dispersed is deteriorated in its stability to easily gel. On the other hand, when a mean particle size of the silica particles exceeds 20 nm, the resin coating layer is deteriorated in the formability of the coating layer, and tends to be deteriorated in the corrosion resistance and the coating applicability. Therefore, a mean particle size of the silica particle is preferably 4 to 20 nm.
[0077] In addition, as a method for measuring a mean particle size of the silica particles, the Sears method (4 to 6 nm) or the BET method (4 to 20 nm) is desirable.
[0078] As a silica particle usable in the resin composition for forming a coating layer according to the present invention, a silica particle usually known as a colloidal silica is desirable; and, for example, ^'XS", "SS", "40", "N", and "UP", etc.,
of "SNOWTEX®" series [colloidal silica manufactured by NISSAN
CHEMICAL INDUSTRIES, LTD.) are preferably used.
(1-4) Silane Coupling Agent
[007 9] The resin composition for forming a coating layer used
in the present invention, includes a silane coupling agent. A
silane coupling agent contributes to the improvement in the
adhesion property between the metal sheet and the resin coating

layer formed thereon, as well as the improvement in the corrosion resistance, the deep drawing workability, and the coating applicability.
[0080] A content of the silane coupling agent in the resin composition for forming a coating layer, is preferably 5 parts by mass or more, preferably 7 parts by mass or more, and 25 parts by mass or less, preferably 20 parts by mass or less, based on the total amount of lOOparts by mass of the acrylic ure thane-based resin (non-volatile resin component). When a content of the silane coupling agent is too small, the reactivity between the acrylic urethane-based resin and the silica particles is decreased, causing the corrosion resistance, the coating applicability, and the deep drawing workability are deteriorated. [0081] On the other hand, when a content of the silane coupling agent is too large, a gel-like substance is generated, causing the stability of an aqueous solution in which the resin is dispersed (described later) to be deteriorated; and an amount of a silan coupling agent which does not contribute to the reaction, is increased, sometimes causing the adhesion property between the metal sheet and the resin coating layer formed thereon.
[0082] As the silane coupling agent, a silane coupling agent represented by the formula (1) is preferably used:

[Formula 3]
R^ R--X-Si-R^ (1)
wherein, R^ represents a glycidoxy group^ R" and R^, lower alkoxy groups, respectively, R4, a lower alkoxy group or a lower alkyl group, and X, a lower alkylene group. Herein, "lower" means having 1 to 5 of carbon atoms, more preferably having 1 to 3 carbon atoms.
[0083] By containing the silane coupling agent, the aqueous solution in which the resin is dispersed can be improved in the coating applicability, and the resultant surface treated metal sheet can be improved in the corrosion resistance. As silane coupling agents having a glycidoxy group at the end represented by the formula (1), Y^giv^idoxypropyltrimethcxysilane, Y-glycidoxypropylmethyldietoxysilane, vinyl tris (p-methoxyethoxy) silane, etc., can be cited. Because a silane coupling agent having a glycidoxy group is rich in the cross-linking reactivity to an acrylic urethane-based resin, a resin coating layer obtained by using a silane coupling agent having a glycidoxy group becomes firm, leading to the improved corrosion resistance and the deep drawing workability. (1-5) Other Additives
[0084] In the present invention, polymer chains may be cross-linked by a chemical bond using a reaction between functional groups, in order to form a firmer coating layer. A

cross-linking agent used for forming a cross-linkage between polymer chains is not particularly limited, as long as the cross-linking agent has two or more of functional groups capable of reacting with a carboxyl group, within a single molecule. Suitable examples thereof include cross-linking agents containing aziridine groups as follows, for example: poly glycidylethers, such as sorbitol polyglycidyl ether, (poly) glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, and (poly) ethylene glycol glycidyl ether; glycidyl group-containing cross-linking agent, such as poly glycidyl amine; bifunctional aziridine compounds, such as 4,4-bis(ethyleneimine carbonylamino) diphenyimethane, N,N-hexamethylene-l,6-bis(1-aziridine carboxyamide), N,N-diphenylmethane-4,4-bis(1- aziridine carboxyamide), toluene bis aziridine carboxyamide; tri-or more-functional aziridine compounds, such as tri-1-aziridinyl phosphine oxide, tri[1-(2-methyl) aziridinyl] phosphine oxide,
trimethylolpropane tris (p-aziridinyl propionate), tris-2, 4,6-{1-aziridinyl)-1,3,5-triazine, tetramethyl propane tetra aziridinyl propionate; and derivatives thereof. One or more of them may be used.
[0085] The cross-linking agent is preferably used in an amount of 1 part by mass or more, more preferably 5 parts by mass or more, and 20 parts by mass or less, more preferably 15 parts by mass or less, based on 100 parts by mass of the acrylic

urethane-based resin. When an amount of use of the cross-linking agent is too small, the effects of cross-linkage by a chemical reaction (effect of improvement in the corrosion resistance and the deep drawing workability by forming a firmer coating layer) cannot be fully obtained; on the other hand, when an amount of use thereof is too large, the aqueous solution in which the resin is dispersed is increased in its viscosity, sometimes causing the stability thereof to be deteriorated.
[0086] In addition, a lubricant may be contained in the composition for forming a resin coating layer, in an amount which does not impair the corrosion resistance and the deep drawing workability. Examples of the lubricants include solid lubricants, for example, polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax, carnauba wax, paraffin wax,
montan wax, rice wax, Teflon® wax, carbon bisulfide, and graphite; and one or more of them can be selected for use. (2) Methods for Preparing Aqueous Dispersion Solution of Resin, and for Forming Resin Coating Layer
[0087] An aqueous dispersion solution of resin in which the resin composition for forming a coating layer is dispersed in water or a solvent of which main component is water, is used for producing the surface treated metal sheet according to the present invention. The aqueous dispersion solution of resin used in the present invention, may contain a diluent solvent, an anti-skinning agent, a leveling agent, an antifoaming agent, an osmosis agent, an emulsifier, a film formation auxiliary agent,

a color pigment, a thickener, and a lubricant, etc. [008B] A method for preparing the aqueous dispersion solution of resin is not particularly limited; and the aqueous dispersion solution of resin can be obtained by mixing predetermined amounts of silica particles, a silane coupling agent, and as necessary, additives such as a cross-linking agent, and a lubricant, in the aqueous dispersion solution of acrylic urethane-based resin. The silica particles, silica coupling agent, lubricant, and cross-linking agent, may be added at any stage; however, it is desirable that the aqueous dispersion solution should not be heated such that a cross-linking reaction does not proceed to generate a gel, after adding the silane coupling agent and the cross-linking agent. For example, the aqueous dispersion solution of resin is preferably stored at a
temperature of 25°C or less. A viscosity of the aqueous dispersion solution of resin is not particularly limited, and a suitable viscosity may be appropriately adopted in accordance with the formation method, or the like.
[0089] A method for forming the resin coating layer on the metal sheet is not particularly limited, and a conventionally known applying method can be employed; for example, the aqueous solution only has to be applied on one or both faces of the metal sheet by using the roll coater method/ the spray method, or the curtain flow coater method, etc., and subsequently be dried by heating. The temperature of drying by heating is not particularly limited; howevei", when i"^'"-^ = ^v-^cc-i i-niri nn s^fAn^. 3 f^mnpj'^tDrp

at which a cross-linking reaction proceeds by the cross-linking agent in use, is preferably adopted. When a polyethylene wax is used as a lubricant, the workability in the subsequent processes can be good, if the wax maintains its spherical shape. Therefore, the drying by heating is preferably performed such that the temperature of the metal sheet is 70 to 130°C, not so as to impair the spherical shape of the wax. When the temperature of the metal sheet is high at the time of applying the aqueous dispersion solution of resin, a component in the aqueous dispersion solution of resin sometimes reacts with the metal sheet before the coating layer is dried, or an uneven appearance sometimes occur due to evaporation of water before the coating is dried; therefore, the temperature of the metal sheet is preferably SCC or less, at the time of applying the aqueous solution.
[0090] The azomethine cross-linked structure is formed by a cross-linking reaction, which proceeds with the removal (evaporation) of an alkali component used for neutralization of water and the resin component, when a functional group capable of forming the azomethine cross-linked structure, is present in the coating layer at the time of forming the resin coating layer. Accordingly, under such conditions, the azomethine cross-linked structure is formed regardless of temperature. [0091] Metal sheets used in the present invention are not particularly limited; however, a zinc-based plated steel sheet is desirable, for example, a hot dip pure zinc-coated steel sheet, a hot dip zinc alloy-coated steel sheet, a zinc-5% aluminum alloy

plated steel sheet, a zinc-551 aluminum alloy plated steel sheet, an electro-galvanized pure zinc steel sheet, an electro-galvanized zinc-nickle alloy steel sheet, an aluminum sheet, a titanium sheet, etc., are preferably used. Further, pre-treatments of the metal sheet by using Co or Ni, an inhibitor, or various chromate-free or hexavalent chromate-free materials, may be performed before forming a resin coating layer. [0092] An adhesion amount (thickness) of the resin coating layer to the metal sheet, is preferably 0.05 g/m^ or more after drying, more preferably 0.2 g/m" or more, and 1 q/m" or less, more preferably 0.7 g/m" or less. When an adhesion amount is too small, the corrosion resistance is deteriorated; on the other hand, when too large, the blackening resistance is sometimes deteriorated. [0093] In the FT-IR measurement, a peak originating from the azomethine cross-linkage is usually observed at about 1660 cm""; however, the resin coating layer directed to the present invention contains an urethane bond, of which peak is observed in the same region, hence, it is difficult to clearly distinguish and confirm those structures by the FT-IR. However, in the resin coating layer according to the present invention, a peak at about 1660 cm""'" is amplified and confirmed, compared to the measurement of another sample which has been made by using, for example, a resin containing a urethane bond but not the azomethine cross-linkage, and made under the same conditions as that of the resin coating layer according to the present invention. [0094] As described above, it is difficult to guantify an

amount of the azomethine cross-linkage present in the resin coating layer; however, an amount of the azomethine cross-linkage present therein (theoretical amount), which is calculated from, for example, a feed amount when producing the acrylic urethane-based resin, is preferably 5 to 120 milliequivalents based on the total amount of 100 g of the polyurethane and the (metha) acrylic-based polymer, more preferably 10 to 90 milliequivalents.
[0095] The resin coating layer formed on the surface treated metal sheet according to the present invention, has a high hardness. Specifically, a coating layer, which has been generated by applying the acrylic urethane-based resin to a glass plate with a #20-bar coater, and by drying at 0 to 105°C, has a Sward rocker hardness of 30 or more, more preferably 55 or more, still more preferably 40 or more.
[0096] The surface treated metal sheet according to the present invention may be used as is processed in accordance with applications, or used after subjecting it to the electro deposition, the powder coating, the silk-screen printing, or the like, which are performed under the conventional conditions.
Examples
[0097] Hereinafter, the present invention will be described in detail with reference to Examples; however, the invention should not be limited by the following Examples, and any modification and embodiment within the range not departing from

the spirit of the invention should be included within the scope of the invention. The evaluation methods adopted in Examples are as follows.
(1) Corrosion Resistance
[0098] With respect to the resultant surface treated metal sheets (resin coated steel sheets}, the salt spray test of flat plates having their edges sealed, were carried out in accordance with JIS-Z 2371 {11.1 neutral salt spray test). The corrosion resistance was evaluated by the time before an area of white corrosion reached 5% of the total area of a plate, in accordance with the following evaluation standard. (Evaluation Standard)
: generation of a white corrosion: 240 hours or more
0 : generation of a white corrosion: 120 hours or more to less than 240 hours
: generation of white corrosion; 72 hours or more to less than 120 hours
x; generation of white corrosion: less than 72 hours
(2) Deep Drawing Workability
[0099] With respect to the resultant surface treated metal sheets (resin coated steel sheets), press molded articles were produced by using the 80 ton-crank press (80-TON Crank press manufactured by AIDA ENGINEERING, LTD., See Fig.l); and mold galling and blackening phenomena (blackening resistance) on the sliding faces of the articles were visually observed to evaluate.
(Press-molding conditions)

•Wrinkles control pressure=9.8N
•molding speed=40 SPM
•bead height=3 mm
•slot R(r'3) = 2 mm
•die R(r3) = 0.5 mm
•die diameter: 51.640 mm
•punch diameter: 50.120 mm (Evaluation standard of mold galling)
: Area where galling occurs is less than 40% based on the whole area.
0 : Area where galling occurs is 40% or more and less than 60% based on the whole area.
: Area where galling occurs is 60% or more, and less than 80% based on the whole area.
x: Area where galling occurs is 80% or more based on the whole area. ,'Evaluation standard of blackening phenomenon)
: No blackening phenomenon was observed on the sliding surface of a press molded product (extremely good).
0: Good (see Fig.2 (a)).
: Poor
x: Extremely poor (see Fig.2 (b)) (3) Coating Applicability
[0100] Melamine alkyd-based paint ("Amilack® #1000" manufactured by Kansai Paint Co. , Ltd.) was applied to a resultant

surface treated metal sheet (resin coated steel sheet) by using the spray coating, such that a thickness of the coating was about 20 nm after drying; and the post-coating was performed after baking at 130°C for 20 min. Subsequently, the sample was iramersed in boiling water for 1 hour, then taken out to stand at room temperature (25°C) for 1 hour. The sample was made cuts on its surface so as to have 100 grids each of which had a size of 1 mm > : Rate of the remaining grids is 95% or more.
0: Rate of the remaining grids is 8 0% or more, and less than 95%.
: Rate of the remaining grids is 70% or more, and less than 80%.
x: Rate of the remaining grids is less than 70%. {4) Hardness: Sward Rocker Hardness
[0101] An aqueous dispersion solution of each resin obtained from the following Production Examples, was applied to a glass plate having its size of 200 mm long x 150 mm wide with a #20 bar coater to make a specimen for evaluation. Sward rocker hardness

of a resin coating layer was measured in accordance with JIS K 5400-1959.
(5) Softening Point of Resin
[9102] In order to measure a softening point of a resin, a certain amount of an aqueous dispersion solution of resin was taken in a Teflon dish to be dried at 40°C in a dryer. A resin solid thus obtained was subjected to a thermomechanical analysis measurement under the following conditions. •Measurement method: thermomechanical analysis/penetration mode (TKA)
•Test equipment: TMA/SS120 manufactured by Seiko Instruments Inc.
"Test condition
measurement temperature: room temperature to 250°C
heating rate: S^C/min
load: 5 gf
atmosphere: argon gas current of 100 ml/min (Preparation of Aqueous Dispersion Solution of" Resin) Production Example 1: Preparation of Aqueous Dispersion Solution of Acrylic Urethane-based Resin {H-MD 1-based Urethane Acrylic Resin)
[0103] In a 1.0 kg-synthesis reactor which is able to be pressurized and equipped with a stirrer, a heater for heating, a thermometer, and a temperature controller, 24.3 g of polyester polyol ("TA-22-636" manufactured by Hitachi Chemical Co., Ltd.)

made from dimer acid, trimethylolpropane, and diethylene glycol, as a polyol component, 3.89 g of 1, 4-cyclohexandimethanol, 22.52 g of dimethylol propionic acid, and 8.82g of dihydroxyacetone
(manufactured by Merck Ltd., JAPAN), were placed; and subsequently, 96,01 g of a reaction solvent made by mixing 37 0.01 g of butyl acrylate, 370.01g of n-butyl methacrylate, 13.32g of diacetone acrylamide, 13.32g of methyl ethyl ketone, and 1.51g of methoquinone, was added therein and stirred such that the whole system was dispersed uniformly.
[0104] Then, after adjusting the heat of a mixed solution of the above polyol and acrylic-based monomer at 20°C, 128.81g of fi ^■yp^nat^f^ f]if->4pT} ig added therein as an isocyanate component, followed by addition of 0.12 g of dibutyltin dilaurate. After the generation of heat was completed,
the reaction solution was heated to 90 to 95'C over 1 hour, and their reaction was promoted for 2.5 hours. Subsequently, after cooling the reaction solution to 50°C, 96.01g of the reaction solvent containing the above acrylic monomer was introduced into the synthesis reactor; and an acrylic monomer-containing
prepolymer was obtained by stirring the solution at SCc for 1 hour. An content of an isocyanate group (NCO) in the obtained prepolymer was 3.9% (theoretical value: 3.96%; NCO/OH ratio: 1.58) . [0105] After heating 250 g of the above acrylic
monomer-containing prepolymer to SO^C, 11.18 g of triethylamine

was added therein to neutralize a carboxylic group. 45.64 g of an anionic surfactant (^'Alscope TH-330" (aqueous solution with 27% of effective components): manufactured by TOHO Chemical Industry Co., LTD), and a solution made by mixing 358.94 g of ion-exchange water with 1.23 g of an aqueous azo-based polymerization initiator ("VA-044" manufactured by Wako Pure Chemical Industries, Ltd.), were introduced in the acrylic monomer-containing prepolymer thus neutralized over 15 minutes. After confirming the generation of heat had been completed, the solution was subjected to a chain extension reaction by adding a hydrazine aqueous solution which was made by diluting 7.25 g of 80%- hydrazine hydrate with 72.54 g of ion-exchange water. The solution was stirred at 65°C for 60 min after the addition of the hydrazine aqueous solution was completed. Then, 0 .1 g of "KS-530"
(form inhibitor manufactured by Shin-Etsu Chemical Co ., Ltd.) was added therein to obtain a dispersion solution 1.
[0106] After heating 300.00 g of the above dispersion solution to 50°C, 152 . 04 g of a reaction solvent in which the above acrylic monomer was mixed, and a polymerization initiator aqueous solution in which 274.02 g of ion-exchange water and 1.49 g of a water-soluble azo-based polymerization initiator ware mixed, were introduced in the dispersion solution 1 over 45 minutes to be stirred at 55 to 60°C for 4 hours. Then, an aqueous solution in which 3.87g of adipic acid dihydrazide was dissolved in 7,19g of ion-exchange water, was added therein to stir the solution at

55 to 60'C for 3 hours, followed by cooling the reaction solution to obtain an aqueous dispersion solution of acrylic urethane-based resin.
Production Example 2 : Preparation of Aqusous Dispersion Solution of Carboxylic Group-containing Polyurethane
[0107] InaO.8 L-synthesis reactor equipped with a stirrer, a heater for heating, a thermometer, and a temperature controller, 50g of polytetramethylene ether glycol (average molecular weight 1000, manufactured by Hodogaya Chemical Co., Ltd.) as a polyol component, 14 g of 1,4-cyclohexane dimethanol, and 20g of dimethylol propionic acid, were placed; and 30.Og of N-methyl pyrrolidone were added therein as a reaction solvent. Then, 104 g of tolylene diisocyanate was added therein as a isocyanate
component, and the mixture solution was heated to 80 to 85°C and the reaction was promoted for 5 hours. An NCO content in the obtained prepolymer was 8.9%.
[0108] The prepolymer was further added with 16g of triethyl amine to be emulsified at 50°C for 4 hours; and further subjected to a chain extension reaction to obtain an aqueous dispersion solution of carboxylic group-containing polyurethane resin. Production Example 3: Preparation of Aqueous Dispersion Solution of Ethylene-Unsaturated Carboxylic Acid Copolymer [0109] In a 0.8L-autoclave for emulsification, which is equipped with a stirrer, a heater for heating, a thermometer, and a temperature controller, 626 parts by mass of water, 160 parts

by mass of an ethylene-acrylic acid copolymer ("PRIMACOR® 5990 1" manufactured by The Dow Chemical Company, acrylic acid:20 mass %, melt index [MI):1300, acidvalue:150), and0,6equivalents of trimethylamine and 0.15 equivalents of sodium hydrate based on the total carboxylic groups contained in the above ethylene-acrylic acid copolymer, were placed; and rapidly stirred at 150°C under fe-Po- atmosphere, followed by cooling the reaction
solution to 40'^C to obtain an aqueous dispersion solution of ethylene-acrylic acid copolymer.
Production Example 4 : Preparation of Aqueous Dispersion Solution of Ethylene-Unsaturated Carboxylic Acid Copolymer (Addition of Cross-Linking Agent)
[0110] As a cross-linking agent, 4, 4-bis(ethylene-imino carbonylamino) diphenylmethane ("CHEMITITE® DZ-22E" manufactured by NIPPON SHOKUBAI CO., LTD.) was added in the aqueous dispersion solution so that it was used in an amount of 5 parts by mass based on 100 parts by mass of a non-volatile resin component in the ethylene-acrylic acid copolymer. Production Example 5: Preparation of Aqueous Dispersion Solution of Ethylene-Acrylic Acid Copolymer
[0111] In an autoclave having a 1. OL-emulsifying equipment, which was equipped with a stirrer, a heater for heating, a thermometer, and a temperature controller, 200.0 g of an ethylene-acrylic acid copolymer ("PRIMACOR® 5990 I" manufactured by The Dow Chemical Company, monomer unit derived from acrylic

acid: 20 mass %, melt index(MI):1300, weight average molecular weight; 20,000, acid value: 150), 8.0 g of a polymaleic acid aqueous solution ('^NONPOL PMA-50W" manufactured by NOF CORPORATION, weight average molecular weight: about 1,100 indicated as the molecular weight of polystyrene, solid content: 50 mass %) , 33.5 g of trimethylamine (0,63 equivalents based on the total carboxylic groups in the ethylene-acrylic acid copolymer), 6. 9 g of 481-NaOH aqueous solution (0.15 equivalents based on the total carboxylic groups in the ethylene-acrylic acid copolymer), 3.5 g of tall oil fatty acid ("HARTALL FA~3" manufactured by HARIMA CHEMICALS, INC.), and 792.6 g of ion-exchange water were placed; and the autoclave was tightly sealed. After stirring the mixture at 500 rpm at 150°C for 3 hours, the mixture was cooled to 30°C. Subsequently, 10.4 g of a si lane coupling agent ("TSL8350" manufactured by GE Toshiba Silicones) , 31.2g of polycarbodiimide ("SV-02" manufactured by Nisshinbo Industries, Inc., weight average molecular weight: 2,700, solid content: 40 massI), and 72.8g of ion-exchange water, were added therein, and subsequently the mixture was stirred for 10 minutes to obtain the aqueous dispersion solution.
(Softening Point of Aqueous Dispersion Solution of Resin and Sward Rocker Hardness) (Experimental Example 1)
[0112] The aqueous dispersion solutions of acrylic urethane-based resin obtained in the above Production Examples 1 to 3 and 5, the aqueous dispersion solution of carboxylic

group-containing polyurethane resin, and the aqueous dispersion
solution of ethylene-acrylic acid copolymer, were measured for their softening points and Sward rocker hardness and the results were shown in Table 1.

[Table 1]
Production Example Softening Point ("C) Sward Rocker Hardness
Example Production Examplel 189 41
Comparative Example Production Example2 120 12
Comparative Example Production Example3 57 34
Comparative Example Production Examples 66 34
(Preparation of Aqueous Dispersion Solution of Resift for Forming Coating Layer, and Production of Surface Treated Metal Sheet) (Experimental Example 2)

[0113;

Silica particles ("SNOWTEX® XS" manufactured by

NISSAN CHEMICAL INDUSTRIES, LTD., mean particle size: 4 to 5 nm.) were mixed in: the aqueous dispersion solutions of acrylic urethane-based resin obtained in the above each Production Example; the aqueous dispersion solutions of carboxylic group-containing polyurethane resin; and mixture solutions of the aqueous dispersion solution of ethylene-acrylic acid copolymer and the aqueous dispersion solution of ethylene-acrylic acid copolymer, in accordance with the formulation illustrated in Table 2, so that the total amount of the two was 100 parts by mass indicated as the non-volatile component amount. Subsequently, 10 parts by mass of-v-glycidoxypropyltrimethoxysiiane ("KBM403" manufactured by Shin-Etsu Chemical Co. Ltd.) was added therein

to prepare an aqueous dispersion solution of resin for forming a coating layer.
[0114] The aqueous dispersion solution of resin for forming a coating layer was applied to the surface of an electro-galvanized pure zinc steel sheet with a squeeze roll; and the coating layer was dried by heating at 90°C of the sheet temperature to obtain a surface treated metal sheet (resin-coated steel sheet) on which a resin coating having an adhesion amount of 0.4 g/m^ was formed. The resultant resin-coated steel sheets were evaluated for the corrosion resistance and the deep drawing workability; and the results were jointly shown in Table 2. It is noted that, as the above electro-galvanized pure zinc steel sheet, an electro-galvanized pure zinc steel sheet without chromate plating (adhesion amount of zinc: 20 g/m", sheet thickness:0.8 mm) was used.

[Table 2]
Steel Sheet
No. Formulation of non-volatile resin
component and silica
particles (parts by mass) Mixing rate of resin components Corrosion
Resistance Deep Drawing Workability Coating Applicability

resin component silica particles AU PU EC EA
Galling Resistance Blackening Resistance

1 45 55 1 ~ — — @ © o ©
2 40 60 1 — — — © © @ ©
3 35 65 1 — — — @ © © ©
4 45 55 — 1 — — @ o A ©
5 40 60 — 1 — — @ o A ©
6 35 65 — 1 — — @ 0 A ©
7 45 55 — 5 — © o X ©
8 40 60 — 5 — © o X ©
9 35 65 — 5 — © o X @
110 45 55 — — — © A X @
111 40 60 — — — © A X ©
fl2 35 65 — — — © o X o
113 45 55 — — — 1 © 0 X ©
114 40 60 — — — 1 © o X ©
ri5 35 65 „ — — 1 @ 0 A o

[0115] In Table 2, AU represents a non-volatile resin component in the aqueous dispersion solution of acrylic urethane-based resin; PU, a non-volatile resin component in the aqueous dispersion solution of carboxylic group-containing polyurethane resin; and EC, a non-volatile resin component in the aqueous dispersion solution of ethylene-unsaturated carboxylic acid copolymer.
[0116] Steel sheets Nos. 1 to 3 were surface treated metal sheets having resin coating layers formed by using the aqueous dispersion solution of acrylic urethane-based resin in Production Example 1. From the results of Table 2, all of these steel sheets were excellent in the corrosion resistance and the deep drawing workability.
[G117] On the other hand, steel sheets Nos, 4 to 6 had resin coating layers formed by using the aqueous dispersion solutions of carboxylic group containing-urethane resin in Production Example 2; and steel sheets Nos. 7 to 9 had resin coating layers formed by using the mixture solutions of the aqueous dispersion solution of carboxylic group-containing urethane resin in Production Example 2, and the aqueous dispersion solution of ethylene-unsaturated carboxylic acid copolymer in Production Example 4. All of these steel sheets were deteriorated in the blackening resistance compared to the steel sheets Nos. 1 to 3. It is thought that this is because the resin coating layers did not have sufficient hardness due to the insufficient content of the acrylic resin.

[0118] Steel sheets Wos. >& to l-g" had resin coating layers formed by using the aqueous dispersion solution of ethylene-unsaturated carboxylic acid copolymer in Production Example 4; and steel sheets Nos . -t^ to Jr^had resin coating layer formed by using the aqueous dispersion solution of ethylene-unsaturated carboxylic acid copolymer in Production Example 5. All of these steel sheets were deteriorated in the blackening resistance compared to the steel sheets Nos. 1 to 4 . It is thought that this is because the resin coating layers had lower softening points. (Experimental Example 3)
[0119] An aqueous dispersion solution of resin for forming a coating layer, was prepared as follows: the aqueous dispersion solution of acrylic'urethane-based resin produced in the above Production Example 1, and silica particles ("SNOWTEX® XS" manufactured by NISSAN CHEMICAL INDUSTRIES, LTD., mean particle si2e:4 to 6 nm) were mixed in accordance with the formulation illustrated in Table 2, so that the total amount of the two were 100 parts by mass indicated by the amount of non-volatile components; and subsequently 10 parts by mass of V-glycidoxypropyltrimethoxysilane ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd.) was added therein. [0120] The aqueous dispersion solution of resin for forming a coating layer was applied to the surface of an electro-galvanized pure zinc steel sheet with a squeeze roll; and

the coating layer was dried by heating at SO^C of the sheet temperature to obtain a surface treated raetal sheet (resin-coated steel sheet) on which a resin coating having an adhesion amount of 0.4 g/m^ was formed. The resultant resin-coated steel sheets were evaluated for the corrosion resistance and the deep drawing workability; and the results were shown in Table 3. It is noted that, as the above electro-galvanized pure zinc steel sheet, an electro-galvanized pure zinc steel sheet without chroma te plating (adhesion amount of zinc: 20 g/m^, sheet thickness: 0.8 mm) was used.

[Table 3]
Steel Sheet No. Formulation of non-volatile resin component and silica particles{parts by mass) Corrosion Resistance Deep Drawing Workability Coaling Applicability

Resin component Silica particles
Galling Resistance Blackening Resistance

10 5 95 X A © o
11 10 90 X A © o
12 15 85 X o © o
13 20 80 X o © o
14 25 75 A o © o
15 30 70 o © © ©
16 35 65 @ © © ©
17 40 60 @ © © ©
18 45 55 @ © o ©
19 50 50 ® o o ©
20 55 45 @ o A @
21 60 40 @ 0 X @
22 70 30 © o X ©

[0121] Steel sheets Nos. 15 to 19 are surface treated metal sheets having resin coating layers obtained from the aqueous dispersion solution of acrylic urethane-based resin produced in Production Example 1, and the aqueous dispersion solution of resin for forming a coating layer includes: 30 to 50 parts by mass
(indicated as an amount of a non-volatile resin component) of the aqueous dispersion solution of acrylic urethane-based resin; 50 to 70 parts by mass of silica particles, wherein the total amount of the both is 100 parts by mass; and further includes 3 to 20 parts by mass of a silane coupling agent based on the total amount of 100 parts by mass of the acrylic urethane-based resin and the silica particles. All of these steel sheets were excellent in the corrosion resistance and the deep drawing workability.
1 0122] On the other hand, steel sheets Nos . 10 to 14 had resin coating layers formed by using the aqueous dispersion solution of resin in which an amount of the acrylic urethane-based resin was small, and were deteriorated in the corrosion resistance compared to the steel sheets Nos. 15 to 19. Steel sheets Nos. 20 to 22 had resin coating layers formed by using the aqueous dispersion solution of resin in which an amount of the non-volatile resin component was too large, and were deteriorated in the blackening resistance compared to the steel sheets Nos. 15 to 19.
(Experimental Example 4)
The aqueous dispersion solution of acrylic urethane-based resin
thus obtained, and silica particles ("SNOWTEX® XS" manufactured

by NISSAN CHEMICAL INDUSTRIES, LTD., mean particle size: 4 to 6 nm) were mixed together so that an amount of the non-volatile resin component in the aqueous dispersion solution of acrylic urethane-based resin was 40 parts by mass, and an amount of the silica particles was 60 parts by mass; and further 0 to 30 parts by mass of silane coupling agent
(y-glycidoxypropyltrimethoxysilane: "KEM403" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to prepare an aqueous dispersion solution of resin for forming a coating layer.
[0123] The aqueous dispersion solution of resin for forming a coating layer was applied to the surface of an electro-galvanized pure zinc steel sheet with a squeeze roll; and the coating layer was dried by heating at 90°C of the sheet temperature to obtain a surface treated metal sheet (resin-coated steel sheet) on which a resin coating having an adhesion amount of 0,4 g /m^was formed. The resultant resin-coated steel sheets were evaluated for the corrosion resistance and the coating applicability; and the results were shown in Table 4. It is noted that, as the above electro-galvanized pure zinc steel sheet, an electro-galvanized pure zinc steel sheet without chromate plating
(adhesion amount of zinc: 20 g/m', sheet thickness: 0.8 rnia) was used.

[Table 4]
Steel
Sheet
No. Content of Silane Coupling Agent(Parts by Mass) Corrosion Resistance Deep Drawing Workability Coating Apphcabiht}'



Galiing Resistance Blackening Resistance

23 0 X A © X
24 5 0 o @ o
25 7 @ © © ©
26 10 © @ © @
27 15 @ @ © @
28 20 © © @ o
29 25 © o o 0
30 30 © A A X

[0124]

Steel sheets Nos. 24 to No. 29 were surface treated

metal sheets having resin coating layers obtained from the aqueous dispersion solution of acrylic urethane-based resin; and the aqueous dispersion solution of resin for forming a coating layer includes; 30 to 50 parts by mass (indicated as an amount of a non-volatile resin component) of the aqueous dispersion solution of acrylic urethane-based resin; 50 to 70 parts by mass of silica particles; and 5 to 25 parts by mass of a silane coupling agent based on the total amount of 100 parts by mass of the acrylic urethane-based resin and the silica particles . Table 4 shows that any steel plate was excellent in the corrosion resistance, the deep drawing workability, and the coating applicability. [0125] On the other hand, the steel sheet No. 23 had a resin coating layer in which the silane coupling agent was not contained, and the steel sheet No. 30 had a resin coating layer in which the silane coupling agent was contained in more than 25 parts by mass; and the both were deteriorated in the coating applicability

compared to the steel sheets Nos. 24 to 29. (Experimental Example 5)
[0125] An aqueous dispersion solution of resin for forming a coating layer, was prepared as follows: 40 parts by mass (indicated as amount of the non-volatile resin component) of the aqueous dispersion solution of acrylic urethane-based resin produced in the above Production Example 1, and 60 parts by mass of silica particles having its mean particle size of 4 to 100 nm ("SNOWTEX®" series manufactured by NISSAN CHEMICAL INDUSTRIES, LTD.) were mixed; and 10 parts by mass of
y-glycidoxypropyltrimethoxysilane ("KBM403" manufactured by Shin-Etsu Chemical Co . , Ltd.) was added based on 100 parts by mass of the total of the both to prepare an aqueous dispersion solution of resin for forming a coating layer.
[0127] The aqueous dispersion solution of resin for forming a coating layer was applied to the surface of an electro-galvanized pure zinc steel sheet with a squeeze roll; and the coating layer was dried by heating at 90°C of the sheet temperature to obtain a surface treated metal sheet [resin-coated steel sheet) on which a resin coating having an adhesion amount of 0.4 g /m^ was formed. It is noted that, as the above electro-galvanized pure zinc steel sheet, an electro-galvanized pure zinc steel sheet without chromate plating (adhesion amount of zinc: 20 g/m^, sheet thickness: 0.8 mm) was used. [0128] The resultant resin-coated steel sheets were

evaluated for the corrosion resistance and the deep drawing workability, and the coating applicability; and the results were shown in Table 5.

[Table 5]
Steel
Slieet
No. Mean Particle Size
of Silica Particles
(nm) Corrosion Resistance Deep Drawing Workability Coating Applicability



GaUing Resistance Blackening Resistance

31 4-6 © @ @ @
32 10-20 o @ @ ©
33 40-60 A o @ y
34 70 -100 y o @ X
[0129] From the results inTable 5, it is known that a surface treated metal sheet excellent in the corrosion resistance, the deep drawing workability, and the coating applicability, can be obtained by using silica particles having its mean particle size of 4 "CO 20 nm. (Experimental Example 6)
[0130] 40 parts by mass (indicated as an amount of the non-volatile resin component) of the aqueous dispersion solution of acrylic urethane-based resin produced in Production Example 1, and 60 parts by mass of silica particles ("SNOWTEX® XS" manufactured by NISSAN CHEMICAL INDUSTRIES, LTD., mean particle size : 4 to 6 nm) were mixed together; and 10 parts by mass of various silane coupling agents shown in Table 6, was added therein to prepare an aqueous dispersion solution of resin for forming a coating layer. [0131] The aqueous dispersion solution of resin for forming

a coating layer was applied to the surface of an electro-galvanized pui^e zinc steel sheet with a squeeze roll; and
the coating layer was dried by heating at 90°C of the sheet temperature ro obtain a surface treated metal sheet (resin-coated steel sheet) on which a resin coating having an adhesion amount of 0.4 g/m" was formed. The resultant resin-coated steel sheets were evaluated for the corrosion resistance and the deep drawing workability, and the coating applicability; and the results were shown in Table 6. It is noted that, as the above electro-galvanized puire zinc steel sheet, an electro-galvanized pure zinc steel sheet without chromate plating (adhesion amount of zinc: 20 g/m", sheet thickness: 0.8 mm) was used.

[Table 6]
Steel Sheet No. Type of Silane Coupliiij', Agent Stability of
Aqueous Solution
for Forming
Coating Layer Corrosion Resistance Deep Drawing Workability Coating
Applicability




Galling Resistance Blackening Resistance

35 Y-glycidoxypropyltrimelhoxysilane o © @ © @
36 y-glycidoxypropylmethyldiethoky silane o o @ © @
37 P'(3,4-epoxycycIohexyl)ethyltiimelhoxysilane o o @ © ©
38 Y-aminopropyltriethokysilane gelled one day
after being
prepared — — — —
39 y-mercaptopropyltrimethokysilane gelled one day
after being
prepared — — — ~
40 7-(methacryioxypropyl)trimettioxy silane gelled one day
after being
prepared — — — —

[0132] From the results in Table 6, it is known that an aqueous dispersion solution of resin for forming a coating layer can be maintained stably by using a silane coupling agent having a glycidoxy group at its end, as a silane coupling agent (steel sheets Nos. 35 to 37) . Moreover, the steel sheets Nos . 35 to 37 were also excellent in the corrosion resistance, the deep drawing workability, and the coating applicability. (Experimental Example 7)
[0133] 40 parts by mass (indicated as an amount of the non-volatile resin component) of the aqueous dispersion solution of acrylic urethane-based resin produced in Production Example 1, and 60 parts by mass of silica particles ("SNOWTEX® XS" manufactured by NISSAN CHEMICAL INDUSTRIES, LTD., mean particle si2e:4to5nm) were mixed together; and 10 parts by mass of silan
coupling agent (y-glycidoxypropyltrimethoxysilane: "KBM4 03" manufactured by Shin-Etsu Chemical Co., Ltd.) was added therein to prepare an aqueous dispersion solution of resin for forming a coating layer.
[0134] The aqueous dispersion solution of resin for forming a coating layer was applied to the surface of an electro-galvanized pure zinc steel sheet with a squeeze roll; and the coating layer was dried by heating at 9D°C of the sheet temperature to obtain a surface treated metal sheet (resin-coated steel sheet) on which a resin coating having an adhesion amount of 0.05 to 2.0 g/m' was formed. The resultant resin-coated steel

sheets were evaluated for the corrosion resistance, the deep drawing workability, and the coating applicabiliry; and the results were shown in Table 7. It is noted that, as the above electro-galvanized pure zinc steel sheet, an electro-galvanized pure zinc steel sheet without chromate plating (adhesion amount of zinc: 20 g/m^, sheet thickness:0.8 mm) was used. [Table 7]

Steel
Sheet
No Adhesion
Amount
(g/m^) Corrosion Resistance Deep Drawing Workability Coating Applicability



Galling Resistance Blackening Resistance

41 0. 01 X A © X
42 0. 05 0 o © ©
43 0. 1 o o © ©
44 0. 3 @ @ © ©
45 0. 5 @ @ © @
46 0. 8 @ @ © ©
47 1. 0 o @ o o
48 1. 5 0 @ A X
49 2. 0 A @ X X

013:

From the results in Table 7, it is known that a surface

treated metal sheet can be improved in the corrosion resistance, the deep drawing workability, and the coating applicability, by adjusting an adhesion amount of the resin to 0.05 to 1 g/iri". [013 6] A surface treated metal sheet according to the present invention is excellent in the corrosion resistance, the deep drawing workability, and the coating applicability; therefore, the sheet can be preferably used in deep-drawn products for automobiles, home electric appliances, and building materials.

such as audio chassis, computer casings, motor casings, and pulleys.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.



WHAT IS CLAIMED IS:
1. A surface treated metal sheet having a resin coating layer
thereon, and the resin coating layer is formed from a resin
composition for forming a coating layer the resin composition
for forming a coating layer comprising:
30 to 50 parts by mass of an acrylic urethane-based resin;
50 to 70 parts by mass of silica particles having its mean particle size of 4 to 20 nm, wherein the total amount of the both is 100 parts by mass; and further
5 to 25 parts by mass of a silane coupling agent based on the total amount of 100 parts by mass of the acrylic urethane-based resin and the silica particles.
2. The surface treated metal sheet according to claim 1, wherein the acrylic urethane-based resin comprises: a polyurethane obtained from a urethane prepolymer which contains, as raw materials, polyisocyanate, polyol, and dihydroxyalicanoic acid, and is synthesized from the total amount of 3 to 80 parts by mass of the three; and a (metha) acrylic-based polymer obtained from 10 to 97 parts by mass of a (metha) acrylic monomer.
3. The surface treated metal sheet according to claim 1, wherein the acrylic urethane-based resin has at least either a carbonyl group or a hydrazine group in at least either structure of the polyurethane and the (metha) acrylic-based polymer.

4. The surface treated metal sheet according to claim 1,
wherein the acrylic urethane-based resin has a softening point
of 120°C or more and a Sward rocker hardness of 25 or more.
5. The surface treated metal sheet according to claim 1,
wherein the resin coating layer has an azomethine cross-linked
structure.
6. The surface treated metal sheet according to claim 1,
wherein the silane coupling agent has s structure represented by
the following formula (1):
[Formula 1]

Documents:

2801-CHE-2008 FORM-3 10-02-2014.pdf

2801-CHE-2008 AMENDED CLAIMS 10-02-2014.pdf

2801-CHE-2008 AMENDED PAGES OF SPECIFICATION 10-02-2014.pdf

2801-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 10-02-2014.pdf

2801-CHE-2008 OTHER PATENT DOCUMENT 10-02-2014.pdf

2801-CHE-2008 OTHER PATENT DOCUMENT-1 10-02-2014.pdf

2801-CHE-2008 PROOF OF RIGHT DOCUMENT 10-02-2014.pdf

2801-che-2008 abstract.pdf

2801-che-2008 claims.pdf

2801-che-2008 correspondence others.pdf

2801-che-2008 description (complete).pdf

2801-che-2008 drawing.pdf

2801-che-2008 form-1.pdf

2801-che-2008 form-18.pdf

2801-che-2008 form-26.pdf

2801-che-2008 form-3.pdf

2801-che-2008 form-5.pdf

2801-che-2008 others.pdf


Patent Number 258960
Indian Patent Application Number 2801/CHE/2008
PG Journal Number 08/2014
Publication Date 21-Feb-2014
Grant Date 18-Feb-2014
Date of Filing 14-Nov-2008
Name of Patentee KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.)
Applicant Address 10-26, WAKINOHAMA-CHO 2-CHOME CHUO-KU KOBE-SHI HYOGO 651-8585.
Inventors:
# Inventor's Name Inventor's Address
1 KAJITA, TOMIO C/O KAKOGAWA WORKS IN KOBE STEEL LTD KANAZAWA-CHO 1 KAKOGAWA-SHI HYOGO 675-0137.
2 YAMAMOTO, KAYO C/O KAKOGAWA WORKS IN KOBE STEEL, LTD., KANAZAWA-CHO 1, KAKOGAWA-SHI, HYOGO 675-0137
3 TAKAMATSU, TATSUYA C/O TOHO CHEMICAL INDUSTRY CO., LTD., 2931, URAGO-CHO 5-CHOME, YOKOSUKA-SHI, KANAGAWA 237-0062
4 YAMAMURA, KENTARO C/O TOHO CHEMICAL INDUSTRY CO., LTD., 2931, URAGO-CHO 5-CHOME, YOKOSUKA-SHI, KANAGAWA 237-0062
5 KIKUCHI, NORIYUKI C/O TOHO CHEMICAL INDUSTRY CO., LTD., 2931, URAGO-CHO 5-CHOME, YOKOSUKA-SHI, KANAGAWA 237-0062
6 AKIMOTO, MIKIO C/O TOHO CHEMICAL INDUSTRY CO., LTD., 6-4, AKASHICHO, CHUO-KU, TOKYO 104-0044
PCT International Classification Number B32B15/082
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2007-298577 2007-11-16 Japan