TWI403615B - Surface treated metal sheet - Google Patents

Abstract

The invention relates to a surface treatment metal plate with the surface of the metal plate being provided with a resin capsule, wherein, the resin capsule is formed by the following resin capsule forming composites, which contain 30-50 proportion by weight of acrylic acid urethane resin and 50-70 proportion by weight of silica particles with an average particle size of 4-20nm, and the total proportion by weight of the acrylic acid urethane resin and the silica particle is 100, and also contain 5-25 proportion by weight of silane coupling agent according to the total 100 proportion by weightof the acrylic acid urethane resin and the silica particle. The composition leads the metal plate to have corrosion resistance, deep drawing processability and excellent coating performance.

Description

Surface treated metal sheet

The present invention relates to a metal sheet which is excellent in surface treatment of deep drawability, and more particularly to deep draw used in automobiles, home appliances, and building materials, which are suitable for an acoustic chassis, a computer case, a motor case, a pulley, and the like. The surface of the product is treated with a metal plate.

As a material used for parts of household appliances, galvanized steel sheets such as electrogalvanized steel sheets or hot-dip galvanized steel sheets are used, and chromate treatment and phosphate treatment are applied to the galvanized steel sheets to further improve corrosion resistance and coating properties. The inorganic film-treated steel sheet obtained by the chemical conversion treatment. In addition, a resin-coated steel sheet obtained by forming an organic resin film on a surface-treated steel sheet subjected to chromate treatment for further improving corrosion resistance and improving coating property and workability has been proposed.

However, when the motor casing or the like in the home electric appliance is subjected to deep drawing processing, since the sliding friction between the resin-coated steel sheet and the metal mold is generated during the processing, the resin film on the sliding surface is peeled and blackened. The phenomenon of the product significantly damages the appearance of the product, and the resulting black compound adheres to the peripheral device and causes other undesirable phenomena.

In order to solve such problems, various modified resin films have been proposed, for example, a lubricating steel sheet having a resin film having an inorganic polymer compound and a solid lubricant, and an inorganic polymer compound and a solid lubricant are formed to have water solubility. Lubricated steel sheet of resin resin film. However, the film-treated steel sheet having an inorganic polymer as a matrix has an effect of improving the damage of the film blackening during the deep drawing process, but has the following problem: it is easy to cause a coating such as a depression generated when the solution is applied to the steel sheet. The cloth defect is likely to cause black spot rust or white rust due to the high water permeability of the film, and the adhesion of the film after coating is poor.

In recent years, as awareness of environmental issues has increased, steel sheets that do not use hexavalent chromium have been increasingly used in place of chromate treatments conventionally used to improve the corrosion resistance of galvanized steel sheets. Therefore, it is expected to develop a film having more excellent corrosion resistance.

As a resin film which aims to further improve the corrosion resistance, surface treatment of a mixture having a carboxyl group-containing polyurethane resin or a carboxyl group-containing polyurethane resin and an ethylene-unsaturated carboxylic acid copolymer has been proposed. A metal plate (Japanese Patent Laid-Open No. 2005-200757, Japanese Patent Laid-Open No. 2006-43913).

However, in recent years, electrical products have been further improved in performance and miniaturization, and as the dimensional accuracy of processed products has become more stringent, the processing conditions of steel sheets have become more demanding. In particular, in the case of performing deep drawing processing, in order to improve the dimensional accuracy, a molding device having a clearance smaller than the thickness of the processed steel sheet may be used, and the resin coating film and the metal mold may be more severely generated than in the past. Sliding friction causes a significant deterioration in the appearance of the product on the sliding surface. The above-mentioned problems also occur in the above-mentioned prior art film-treated steel sheets, and therefore the demand for improvement in the appearance of processed products is higher than ever.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a surface-treated metal sheet having further improved corrosion resistance, paintability, and deep drawability.

The surface-treated metal sheet of the present invention which solves the above-described problems is a metal sheet having a surface treated with a resin film on the surface of the metal sheet, and the resin film contains 30 to 50 parts by mass of an urethane-based resin and 50 to 70. The cerium oxide particles having an average particle diameter of 4 to 20 nm are contained in an amount of 100 parts by mass in total, and are contained in an amount of 100 parts by mass based on 100 parts by mass of the urethane-based resin and the cerium oxide particles. A resin composition for forming a film of a decane coupling agent in a ratio of 5 to 25 parts by mass is formed.

The urethane urethane-based resin contains a polyisocyanate, a polyhydric alcohol, and a dihydroxyalkanoic acid as a raw material, and these are a total of 3 to 80 parts by mass of the synthesized urethane prepolymer. The polyurethane is preferably a (meth)acrylic polymer obtained from 10 to 97 parts by mass of a (meth)acrylic monomer. Further, the urethane urethane-based resin has at least one of a carbonyl group and a fluorenyl group in at least one of a structure of a polyurethane and a (meth)acrylic polymer. Further, the above resin film preferably further has a crosslinked structure of methylimine.

The urethane urethane-based resin preferably has a softening point of 120 ° C or higher, and the hardness of the sliding type durometer is 25 or more.

The decane coupling agent preferably has a structure represented by the following chemical formula (1).

(In the above chemical formula (1), R ¹ is a glycidoxy group, R ² and R ³ are a lower alkoxy group, R ⁴ is a lower alkoxy group or a lower alkyl group, and X is a lower alkylene group.)

Further, the adhesion amount of the resin film in the metal plate is preferably 0.05 to 1 g/m ² .

The surface-treated metal sheet of the present invention is excellent in corrosion resistance, deep drawability, and paintability.

The surface-treated metal sheet of the present invention is characterized in that the surface of the metal sheet has a surface-treated metal sheet of a resin film, wherein the resin film contains 30 to 50 parts by mass of an urethane-based resin and 50 to 70 parts by mass. The cerium oxide coupling agent having a ratio of 5 to 25 parts by mass based on 100 parts by mass of the total of the urethane urethane resin and the cerium oxide particles, and the cerium oxide particles having an average particle diameter of 4 to 20 nm. The composition for forming a resin film is formed. Hereinafter, the present invention will be described in detail.

(1) Resin composition for film formation (1-1) Acrylic urethane resin

The urethane-based resin used in the present invention contains a (meth)acrylic polymer and a polyurethane. The use of the (meth)acrylic polymer and the polyurethane as described above is because if only the (meth)acrylic polymer is used as the resin component, a resin film having high hardness is formed to ensure processing. Sexuality (blackening resistance), but since the flexibility is low, cracks are likely to occur in the resin film, and corrosion resistance is liable to be lowered. For this reason, it is possible to impart a polyurethane resin and a (meth)acrylic acid which are excellent in flexibility, chemical resistance, and seizure resistance, and which can impart toughness to the obtained resin film. The polymers are used in combination to achieve both workability and flexibility of the resin film (surface-treated metal plate).

Further, an object of the present invention is to provide a surface-treated steel sheet which is less likely to cause an appearance defect such as a blackening phenomenon even when strict processing conditions using a metal mold having a gap smaller than the thickness of the steel sheet to be processed are used. When the above strict processing conditions are employed, a large force is applied to the steel sheet instantaneously. At this time, the resin film provided on the surface of the metal plate is required to have not only the hardness against the impact generated by the contact with the forming device, but also the flexibility to follow the deformation of the steel sheet. Therefore, in order to produce a surface-treated steel sheet having these two properties, the present invention employs an urethane-based resin having the above-described constitution.

Examples of the (meth)acrylic monomer component constituting the (meth)acrylic polymer include a monomer having a carboxyl group such as (meth)acrylic acid, itaconic acid or crotonic acid, and 2-hydroxy(meth)acrylic acid. A monomer having a hydroxyl group such as ethyl ester, propyl 2-hydroxy(meth)acrylate or butyl 4-hydroxy(meth)acrylate, or a (meth)acrylate.

Examples of the acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isodecyl acrylate, isobornyl acrylate, and N,N-dimethylamino acrylate. Ethyl ester, isobutyl acrylate, 2-methoxyethyl acrylate, 3-methoxybutyl acrylate, dodecyl acrylate, n-octadecyl acrylate, tetrahydrofurfuryl acrylate, trihydroxyl Methyl propane acrylate, 1,9-nonanediol acrylate, and the like. Examples of the methacrylate include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and 2-ethylhexyl methacrylate. , lauryl methacrylate, alkyl methacrylate, tridecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, methyl Isobornyl acrylate, 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-hexanediol dimethacrylate, polydimethyl acrylate Propylene glycol ester, trimethylolpropane trimethacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, trifluoroethyl methacrylate, heptafluoromethacrylate Ester ester and the like. These (meth)acrylic monomer components can be used singly or in combination of two or more kinds as needed.

Among the above (meth)acrylic monomer components, butyl acrylate and n-butyl methacrylate are particularly preferable.

The polyurethane of the present invention is preferably obtained by polymerizing a polyisocyanate, a polyhydric alcohol and a hydroxyalkanoic acid, and more preferably synthesizing a urethane prepolymer from a polyisocyanate, a polyhydric alcohol and a hydroxyalkanoic acid and causing it to occur. The chain is extended to obtain a reaction.

The polyisocyanate component constituting the urethane prepolymer preferably has two or more isocyanate groups in one molecule, and specific examples thereof include 4,4'-diphenylmethane diisocyanate and 2,4'-di. Phenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-toluene diisocyanate, 1,4-naphthalene diisocyanate, Yellow-type polyisocyanate such as 1,5-naphthalene diisocyanate, 1,2-benzene diisocyanate, 1,3-benzene diisocyanate, 1,4-phenylene diisocyanate; o-xylene diisocyanate, p-xylene diisocyanate, Difficulty yellowing polyisocyanate such as meta-xylene diisocyanate; 4,4'-bicyclomethane diisocyanate, 2,4'-bicyclomethane diisocyanate, 2,2'-bicyclomethane diisocyanate, hexamethylene di Non-yellowing polyisocyanate such as isocyanate, tetramethylxylene diisocyanate, isophorone diisocyanate or lysine diisocyanate; polymer such as crude toluene diisocyanate or polyphenylene polymethylene isocyanate. These polyisocyanates may be used singly or in combination of two or more. Among the above polyisocyanates, the yellowish-free isocyanate is preferably used from the viewpoint of maintaining the appearance of the metal sheet well.

The polyol component constituting the urethane prepolymer preferably has two or more hydroxyl groups in one molecule, and any of a low molecular weight type and a high molecular weight type can be used. Examples of the low molecular weight type include ethylene glycol, diethylene glycol, 1,3-propanediol, triethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, neopentyl glycol, and 1,4-. Cyclohexanedimethanol, sorbitol, pentaerythritol, glycerin, trimethylolpropane, trimethylolethane, etc., in the above low molecular weight polyol, trimethylolpropane, 1,4-cyclohexane Methanol is preferred. Further, examples of the high molecular weight type polyol include a polyether polyol, a polyester polyol, an epoxy polyol, and a polyoxyalkylene polyol.

The polyether polyol may, for example, be a product obtained by polymerization of an epoxide such as ethylene oxide, propylene oxide or tetrahydrofuran, or one or two or more kinds of epoxides with water, ethylene glycol or propylene glycol. A product obtained by addition of diethylene glycol, cyclohexanedimethanol, glycerin, trimethylolpropane, pentaerythritol or bisphenol A.

The polyester polyol may, for example, be a polyester polyol obtained by polycondensation of a diol with a dibasic acid, and examples of the diol component include ethylene glycol, diethylene glycol, and 1,4-butanediol. Neopentyl glycol, 1,6-hexanediol, 1,5-methylpentanediol, 1,4-cyclohexanedimethanol, etc., and examples of the dibasic acid include adipic acid and isophthalic acid. Terephthalic acid, azelaic acid, sebacic acid, other dimer acids, and the like. The above "dimer acid" generally means a dimer produced by dimerizing an unsaturated long-chain aliphatic monocarboxylic acid having 13 to 22 carbon atoms or an ester thereof, specifically, having 18 and 22 carbon atoms. The unsaturated carboxylic acid-derived dimer acid having 36 or 44 carbon atoms, a dimer acid derived from an unsaturated fatty acid having 18 carbon atoms including linoleic acid or flax, and the like. A polyester polyol containing a dimer acid in the above polyester polyol is preferred.

Examples of the dihydroxyalkanoic acid constituting the above urethane prepolymer include 2,2-dimethylol acetic acid, 2,2-dimethylolpropionic acid, and 2,2-dimethylolbutanoic acid. As the dimethylol butyric acid or the like, dimethylolpropionic acid or dimethylolbutanoic acid is preferably used from the viewpoints of reactivity, solubility, and the like.

The resin film of the surface-treated metal sheet of the present invention preferably has a crosslinked structure of methylimine. The cross-linking structure of the imine is a structure represented by the following formula (2), and it is preferably formed by reacting an organic hydrazine compound with a ketone-based or aldehyde-based carbonyl compound.

By forming a crosslinked structure of the imine in the resin film, the fastness of the rubbing rubbing of the ethanol impregnated cloth is improved, and the konig hardness of the resin film and the 100% modulus (deep drawing stress at 100% deep drawing) are increased, thereby being able to be improved. The physical properties of the surface treated metal sheets. Further, since the reaction between the organic hydrazine compound and the carbonyl compound can be carried out by removing (volatile) the water in the coating film and the alkali component used for the neutralization of the resin, the reaction can be carried out under the conditions established under the above conditions. Nothing. Therefore, it is not necessary to perform special operations on the crosslinking reaction. Further, since it is self-crosslinking, it is not necessary to add a crosslinking agent such as formaldehyde to the crosslinking reaction.

The form of the urethane urethane-based resin which can form the above-mentioned methylimine cross-linking is exemplified by the following 1 to 3.

1: an urethane urethane-based resin comprising at least one type of polyurethane having a mercapto group and at least one (meth)acrylic polymer having a carbonyl group;

2: an acrylamide-based resin comprising a form of a compound having at least one type of polyurethane and at least one (meth)acrylic polymer having a carbonyl group and having at least two fluorenyl groups,

3: The urethane urethane-based resin contains a form of a compound having at least one type of polyurethane and at least one (meth)acrylic polymer each having a mercapto group and having at least two carbonyl groups.

Regarding the introduction of a mercapto group into a polyurethane, a hydroxyl group capable of reacting with an isocyanate group is used as long as it is synthesized in the synthesis of the urethane prepolymer or in the chain extension reaction of the urethane prepolymer. The hydrazine compound and the chain extender having a thiol group may be used. Further, at this time, in order to prevent the reaction of the sulfhydryl group, it is necessary to first cleave the thiol group with a monohydric aldehyde or a monoketone. Examples of the ruthenium compound include γ-hydroxybutyl hydrazine obtained by blocking a thiol group with a monohydric aldehyde or a monoketone, and a ketone group which is blocked by a ketone/aldehyde having a boiling point of 30 to 200 ° C and reacted with ethanolamine. Aminocarbazide ethyl methacylate or the like. The above hydrazine compound can be produced by reacting a reaction product of a diamine with 0.2 to 2 moles of a (meth)acrylic acid derivative (preferably ethyl acrylate) with hydrazine. In addition, when the resin coating film formed of the resin composition for forming a film containing the urethane-based acrylic resin is dried, the mono- aldehyde and the monoketone used in the chain-blocking of the thiol group are water-dispersed by the resin composition. The alkali component used in the chemical treatment is removed to cause acidification in the coating film system to be separated from the sulfhydryl group. As a result, a sulfhydryl group is formed and a methylenimine crosslinking reaction occurs.

Examples of the diamine include an aliphatic diamine having 2 to 15 carbon atoms, an alicyclic group having 6 to 15 carbon atoms, and an aromatic diamine. Specifically, ethylenediamine and 1,4-ethylamine are exemplified. Butanediamine, 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 2,2,2-trimethyl-1,6-hexanediamine, 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine, bis(4-aminocyclohexyl)methane, and bis(aminomethyl)benzene.

Further, when a polyurethane having a mercapto group is used, the amount of the mercapto group in 100 g of the polyurethane is preferably from 2 to 500 meq. Further preferably, it is 20 to 200 milliequivalents, more preferably 50 to 115 milliequivalents. Therefore, the amount of the above-mentioned ruthenium compound is preferably such that the functional group having reactivity with the isocyanate group in the above ruthenium compound is 100 to 1000 equivalents per equivalent of the isocyanate group of the polyisocyanate constituting the polyurethane. More preferably, it is 300 to 800 milliequivalents, and most preferably 450 to 600 milliequivalents.

When a carbonyl compound having one, preferably two or more isocyanate-reactive functional groups is used in the synthesis of the urethane prepolymer or the chain extension reaction of the urethane prepolymer, The carbonyl group can be introduced into the polyurethane. Examples of such a carbonyl compound include a dihydroxyketone such as dihydroxyacetone, a product obtained by a Michael addition reaction of diacetone acrylamide with a diamine or an alkanolamine, and the like. Further, examples of the carbonyl compound which can be used in the chain extension reaction include a Michael addition product of 2 mol of diacetone acrylamide and 1 mol of diamine.

Further, when a polycarbamate having a carbonyl group is used, the amount of the carbonyl group in 100 g of the polyurethane is preferably from 2 to 230 meq. More preferably, it is 5 to 180 milliequivalents, and most preferably 10 to 55 milliequivalents. Therefore, when a urethane having a carbonyl group is used, the above carbonyl compound is preferably used in an amount equal to 1 equivalent of the isocyanate group of the polyisocyanate constituting the polyurethane to cause isocyanate groups in the above carbonyl compound. The reactive functional group is from 8 to 880 milliequivalents. More preferably, it is 19 to 690 milliequivalents, more preferably 38 to 211 milliequivalents.

On the other hand, a (meth)acrylic polymer having a mercapto group can be obtained by polymerization of a monomer component having a functional group capable of reacting with ruthenium or osmium monohydrate to form a mercapto group. Specific examples of the monomer component include crotonic acid, α-chloroacrylic acid, (meth)acrylic acid, hydrazine chloride or the like, and a (meth) acrylate of a low molecular weight alcohol is particularly preferably used. Examples of the (meth) acrylate of the low molecular weight alcohol include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and (methyl). ) n-butyl acrylate and the like. As the copolymerization component, a vinyl halide compound such as vinyl chloride, vinyl fluoride or vinylidene chloride, a vinyl-aryl compound such as styrene or substituted styrene, or a vinyl group such as butadiene or 2-chlorobutadiene can be used. These monomer components can be used singly or in combination of two or more.

A (meth)acrylic polymer having a mercapto group can be obtained by reacting a homopolymer or a copolymer obtained by polymerizing the above monomer component with hydrazine or hydrazine monohydrate. Further, the functional group which can be converted into a mercapto group is preferably from 5 to 300 meq in 100 g of the (meth)acrylic polymer. More preferably 10 to 200 milliequivalents, most preferably 20 to 150 milliequivalents. Further, the amount of the above hydrazine or hydrazine monohydrate is preferably from 5 to 300 equivalents, more preferably from 10 to 200 equivalents per 100 g of the (meth)acrylic polymer.

Further, when a (meth)acrylic polymer is synthesized and a polyurethane is formed (the chain extension reaction of the urethane prepolymer is carried out), it is preferably introduced in advance with a monoaldehyde or a monoketone. A mercapto chain in a (meth)acrylic polymer.

When a carbonyl group-containing monomer is used as the (meth)acrylic monomer component, a carbonyl group can be introduced into the (meth)acrylic polymer. Examples of such a carbonyl group-containing monomer include acrolein, methacrolein, diacetone acrylamide, acrylamide pentaerythraldehyde, methacrylamide pentaerythritol, and diacetone acrylate.

Further, when a poly(meth)acrylic polymer having a carbonyl group is used, the amount of the carbonyl group in 100 g of the poly(meth)acrylic polymer is preferably from 2 to 230 meq. More preferably, it is 5 to 180 milliequivalents, and most preferably 10 to 55 milliequivalents.

Examples of the compound having two mercapto groups used in the form of the above 2 include diindole dicarboxylate, and specific examples thereof include dioxonium oxalate, diammonium malonate, diterpene succinate, and diammonium glutarate. Bismuth, adipic acid dioxime and the like. The compound having two carbonyl groups used in the form of the above 3 may, for example, be a di- or poly-ketone or a polyaldehyde such as glyoxal, 2,5-hexanedione, glutaraldehyde or succinic dialdehyde.

When a polycarbamate having a mercapto group and a poly(meth)acrylic polymer having a carbonyl group are used (the form of the above 1), the amount of addition is preferably satisfied with respect to the polyurethane The thiol group present is 1 equivalent such that the carbonyl group is 0.02 to 1.6 equivalents. More preferably 0.05 to 0.9 equivalents.

When the above compound having 2 mercapto groups is used (i.e., the form of the above 2), the compound is preferably used in an amount corresponding to the polyurethane and/or (from the urethane-based resin). The carbonyl group of the acrylic polymer has 1 equivalent of 0.02 to 1.6 equivalents, more preferably 0.05 to 0.9 equivalents.

On the other hand, when the above compound having two carbonyl groups (the form of the above 3) is used, the amount thereof preferably satisfies with respect to the polyurethane present in the urethane-based resin and/or The thiol group of the methyl)acrylic polymer has an equivalent weight of from 0.02 to 1.6 equivalents, more preferably from 0.05 to 0.9 equivalents.

The urethane-based resin may be an urethane-based resin obtained by mixing a separately synthesized (meth)acrylic polymer component and a polyurethane component, but in the present invention Acrylic urethane-based resin, after synthesizing a polyurethane or urethane prepolymer, with a synthetic polyurethane (or urethane prepolymer) In the same system, an urethane-based resin obtained by polymerization of a (meth)acrylic polymer is carried out in the presence of these. This is because the polyurethane and the (meth)acrylic polymer are synthesized in the same system to more uniformly maintain the polyurethane and the (meth) in the urethane-based resin. The mixed state of the acrylic polymer.

Therefore, the method for producing the urethane-based resin of the present invention is not particularly limited as long as it is a method of polymerizing the acrylic component in the same system after the synthesis of the polyurethane component, and the existing one can be used. A well-known method. Further, as described later, since the urethane-based resin of the present invention is used as an aqueous dispersion, it is preferred to first prepare an aqueous dispersion in the production stage of the urethane urethane resin. For example, a method in which a polymerization of a (meth)acrylic monomer component is carried out immediately after the production of a urethane prepolymer, and then the obtained urethane urethane resin is water-dispersed; A method of polymerizing a (meth)acrylic monomer component after the water-dispersed prepolymer is dispersed in water. Further, by adding a (meth)acrylic monomer together with a polymerization inhibitor to the synthesis system of the polyurethane prepolymer in advance, a (meth)acrylic monomer can also be used as the aminocarboxylic acid. The solvent used in the synthesis of the ester prepolymer. At this time, after synthesizing the urethane prepolymer, a radical polymerization initiator may be added to polymerize the (meth)acrylic monomer.

The mixing of the polyisocyanate and the polyol in the synthesis of the urethane prepolymer preferably has a NCO/OH ratio of 1.0 to 2.0, more preferably 1.2 to 1.9, most preferably 1.3 to 1.7.

Further, the amount of the hydroxyalkanoic acid to be used with respect to the polyisocyanate or the polyhydric alcohol is preferably used in an amount such that the acid value of the urethane prepolymer is from 20 to 80 mgKOH/g.

The temperature at which the urethane prepolymer is synthesized is not particularly limited, and is preferably a temperature of from 60 to 95 °C. Further, in the synthesis of the urethane prepolymer, a polymerization catalyst may be used as needed. Examples of the polymerization catalyst include organic compounds such as a tin (II) salt of a carboxylic acid, a strong base such as a tertiary amine, an alkali metal hydroxide, an alkoxide, and a phenate. Specific examples include di-n-octyl mercaptan, dibutyl maleate, tin dibutyl diacetate, and dibutyl dilaurate.

The weight average molecular weight (Mw) of the above urethane prepolymer is preferably from 400 to 10,000. More preferably, it is 3000 to 9000, and most preferably 4000 to 8000. Further, the above weight average molecular weight is a value (polystyrene equivalent value) measured by gel permeation chromatography (GPC).

The polyurethane component of the present invention is preferably obtained by extending the urethane prepolymer with a chain extender chain. The chain extension reaction can be carried out before water dispersion, after water dispersion, or simultaneously with water dispersion.

Examples of the chain extender include ethylenediamine, diethylenetriamine, triethylenetetramine, propylenediamine, butanediamine, hexamethylenediamine, cyclohexanediamine, piperazine, and 2-methylpiperazine. Phenylenediamine, toluenediamine, xylenediamine, tris(2-aminoethyl)amine, 3,3'-dinitrophenylene, 4,4'-diaminophenylmethane, An alkyl diamine, m-xylene diamine, isophorone diamine, isophorone diamine, an anthracene derivative or water, and the like, wherein an anthracene derivative is preferred. The anthracene derivative may, for example, be hydrazine; hydrazine monohydrate; monosubstituted hydrazine such as methyl hydrazine or ethyl hydrazine; hydroxyalkyl substituted hydrazine such as 2-hydroxyethyl hydrazine or 2-hydroxypropyl hydrazine; Anthracene dioxime such as diterpene, ethylene dioxime or propylene dioxime; diterpene oxalate, diammonium malonate, diterpene succinate, diammonium glutarate, adipic acid Bismuth, azelaic acid dioxime, aliphatic dicarboxylic acid bismuth, unsaturated aliphatic dicarboxylic acid bismuth, aromatic dicarboxylic acid bismuth, maleic acid diterpene, diammonium phthalate Diterpenoids such as diterpene isophthalate and carbon dioxime. Among them, the best use of hydrazine monohydrate.

The chain extender preferably has a functional group in the chain extender of from 0.3 to 1.7 equivalents per equivalent of the NCO group in the urethane prepolymer, more preferably from 0.5 to 1.5 equivalents, most preferably 0.8. ~ 1.2 equivalents.

The above urethane prepolymer or polyurethane may be emulsified and dispersed in water by neutralization with a base. In addition, in the case of a (meth)acrylic polymer having a carboxyl group or a carboxyl group-containing alkyl ester (described later in detail), the urethane prepolymer or the polyurethane is similar to the urethane prepolymer or the polyurethane. The carboxyl group derived from the (meth)acrylic polymer is also neutralized. Examples of the neutralizing agent which can be used at this time include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, barium hydroxide, and lithium hydroxide; ammonia; triethylamine, N,N-dimethylbutyl a tertiary amine such as a base amine, N,N-dimethylallylamine, N-methylpyrrolidone, tetramethyldiaminomethane or trimethylamine; N-methylethylamine, diisopropylamine a secondary amine such as diethylamine; a primary amine such as propylamine, tert-butylamine, sec-butylamine, isobutylamine, 1,2-dibutylpropylamine or 3-pentylamine; morpholine, a morpholino compound such as N-methylmorpholine or N-ethylmorpholine; a piperazine compound such as piperazine, hydroxyethylpiperazine, 2-methylpiperazine or aminoethylpiperazine; N, N -diethylethanolamine, N,N-dibutylethanolamine, N-(β-aminoethyl)ethanolamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-n-butyl Ethanolamine, N-n-butyldiethanolamine, N-tert-butylethanolamine, N-tert-butyldiethanolamine, N-(β-aminoethyl)isopropanolamine, N,N-diethylisopropyl Alcohol amines such as alcohol amines and 2-amino-2-methyl-1-propanol; ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylam , diamines such as pentaethylene hexamine, aminoethylethanolamine, 1,6-hexanediamine, m-xylenediamine, 1,2-diaminopropane, 1,4-diaminobutane; coconut An aliphatic amine such as an amine, an octylamine, a laurylamine, a stearylamine or an oleylamine, or the like, an EO adduct or the like. Among them, ammonia and triethylamine which are volatilized at the time of formation of the optimum film without leaving a neutralizing agent are more preferable, and triethylamine is more preferable.

Adding the above (meth)acrylic monomer and polymerization initiator after the synthesis of the urethane prepolymer or the chain extension reaction of the urethane prepolymer, or using (meth) When the acrylic monomer is used as a reaction solvent, a polymerization initiator is added to the system after the synthesis of the urethane prepolymer or the chain extension reaction of the urethane prepolymer, and the (meth)acrylic acid is added. Polymerization of monomers.

The amount of the (meth)acrylic monomer is preferably from 10 to 97 parts by mass based on 3 to 80 parts by mass of the total of the polyisocyanate, the polyol, and the hydroxyalkanoic acid which are constituent components of the urethane prepolymer. At this time, the ratio of use of the above urethane prepolymer to the (meth)acrylic monomer depends on the glass transition temperature of the produced (meth)acrylic polymer, but when the urethane is used When the total amount of the prepolymer and the (meth)acrylic monomer is 100 parts by mass, it is preferably 3 to 50 parts by mass based on the urethane prepolymer component, and the (meth)acrylic monomer is 50 to 50 parts by weight. 97 parts by mass, more preferably 3 to 40 parts by mass based on the urethane prepolymer component, and 60 to 97 parts by mass of the (meth)acrylic monomer. Further, the glass transition temperature of the (meth)acrylic polymer derived from the Fox formula is preferably from -30 to 90 ° C, more preferably from -20 to 80 ° C. Further, the acid value of the (meth)acrylic polymer of the present invention is preferably from 0 to 400 mgKOH/g.

Examples of the polymerization initiator in the polymerization of the (meth)acrylic monomer include azobisisobutyronitrile and its hydrochloride, and an azo compound such as 4,4'-azobis(4-cyanovaleric acid); Organic peroxides such as benzamidine peroxide, dicumyl peroxide, lauric acid peroxide, cumene peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, perphosphate, persuccinate, etc. A peroxide such as an inorganic peroxide.

The amount of the polymerization initiator to be used is preferably from 0.05 to 3% by mass based on the total mass of the (meth)acrylic monomer. The temperature at the time of polymerization of the (meth)acrylic monomer is not particularly limited, and it is preferably carried out at 30 to 100 ° C, more preferably at 50 to 70 ° C.

The (meth)acrylic monomer may be emulsified prior to the polymerization reaction, or may be carried out, for example, simultaneously with the emulsification of the urethane prepolymer or when the urethane prepolymer chain is extended. The emulsification of the urethane prepolymer is carried out simultaneously. Further, an anionic surfactant can also be used as needed.

In the synthesis of the urethane urethane resin of the present invention (synthesis of the above urethane prepolymer, chain extension reaction of the urethane prepolymer, and polymerization of the (meth)acrylic polymer For the reaction, a known organic solvent can be used. Examples of the organic solvent include aromatic solvents such as toluene and xylene; ester solvents such as methyl acetate and ethyl acetate; and ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; and ethylene glycol; a glycol ether ester solvent such as monomethyl ether acetate or propylene glycol monoethyl ether acetate; an alcohol solvent such as methanol, ethanol or isopropanol; dimethylformamide or dimethylacetamide; A solvent such as N-methylpyrrolidone. These organic solvents can be used singly or in combination of two or more kinds. Further, when the urethane component is polymerized, a (meth)acrylic monomer component can be used as a solvent. Further, in this case, the polymerization inhibitor may be any conventionally known polymerization inhibitor, and examples of the polymerization inhibitor include methoxyphenol.

In the present invention, the urethane urethane-based resin is preferably a self-dispersible type which is easily dispersed in water or an aqueous solvent containing water as a main component (50% by mass or more). However, when the urethane urethane-based resin is mechanically dispersed in the case where it is difficult to disperse in water or an aqueous solvent, the particle size of the emulsion may become large and the storage stability may be lowered. Therefore, at this time, a surfactant can be used as needed.

As the surfactant, a conventionally known surfactant such as a nonionic, anionic or cationic surfactant can be used, and it is preferable to select the kind and amount according to the purpose without impairing the effect of the invention. Examples of the nonionic surfactant include polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene tetradecyl ether, polyoxyethylene cetyl ether, and the like. Polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene isostearyl ether, polyoxyethylene behenyl ether, polyoxyethylene-2-ethyl-hexyl ether, polyoxyethylene oxide Ether, polyoxyethylene alkyl ether (synthesis), narrow type polyoxyethylene alkyl ether, polyoxyethylene octyl dodecyl (gelbe) ether, polyoxyethylene styrenated phenyl Ether, polyoxyethylene β-naphthyl ether, polyoxyethylene hydrogenated castor oil ether, polyethylene glycol monoalkyl fatty acid ester, polyethylene glycol dialkyl fatty acid ester, polyoxyethylene sorbitan single laurel Acid esters, etc.

Further, when only a nonionic surfactant is used, a stable aqueous dispersion may not be obtained. Therefore, an anionic surfactant, a reactive surfactant, or the like is preferably used in combination. Examples of the anionic surfactant include semi-hydrogenated tallow fatty acid sodium soap salt, sodium stearate soap salt, potassium oleate soap salt, rosin-based disproportionated rosin sodium salt, alkenyl succinic acid dipotassium salt, and dodecyl salt. Sulfate sodium salt, polyoxyethylene alkyl (C12, C13) ether sulfate sodium salt, polyoxyethylene lauryl sulfate ammonium salt, sodium dodecylbenzenesulfonate, higher alkane as a cationic active agent A monoamine salt, a dialkyl ethyl methyl ethyl sulfate salt, or the like.

Examples of the reactive surfactant include polyoxyethylene alkylphenyl ether, its sulfate salt, sulfosuccinic acid type, alkenyl polyoxyalkylene phosphate, and polyoxyethylene alkyl ammonium phosphate glycidyl ether. Additives, etc. Alternatively, a protective colloid such as polyvinyl alcohol may be used instead of the surfactant.

Specific methods for aqueous dispersion, for example, after neutralizing a (meth)acrylic monomer-containing prepolymer with an amine, adding a surfactant, a polymerization catalyst, and water to carry out polymerization to disperse the polymer water a method of liquefying a polymer obtained by neutralizing a prepolymer containing a (meth)acrylic monomer with an amine and a polymerization catalyst by adding an aqueous solution formed of a surfactant and water to disperse the polymer Methods. In either case, the amount of the surfactant is preferably from 0 to 30% by mass based on the total mass of the (meth)acrylic monomer. Further, in the above method, the (meth)acrylic monomer-containing prepolymer may be emulsified by mixing a neutralizing agent (amine) with water.

(1-2) Amount of urethane acrylate resin added

The resin composition for film formation used in the present invention is characterized by containing 30 to 50 parts by mass of the above-mentioned urethane urethane resin and 50 to 70 parts by mass of the average particle diameter of 4 to 20 nm in total of 100 parts by mass. The cerium oxide particles further contain a decane coupling agent in a proportion of 5 to 25 parts by mass based on 100 parts by mass in total. Further, when an aqueous dispersion of an urethane urethane resin is used, the nonvolatile resin component of the aqueous urethane acrylate resin dispersion is preferably 30 to 50 parts by mass.

When the urethane-based resin component is too small, the corrosion resistance and the coating property tend to be deteriorated. On the other hand, when the urethane-based resin component is too large, the blackening resistance tends to decrease. From such a viewpoint, the urethane urethane-based resin is preferably contained 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. Here, the nonvolatile resin component of the aqueous urethane-based resin dispersion is the urethane-based resin, and the non-volatile resin component can be measured by a method known in the art of aqueous dispersion. For example, the aqueous dispersion is heated at 100 ° C to 130 ° C for 1 to 3 hours to evaporate the residue.

It is considered that the above-mentioned blackening resistance is lowered because, for example, in a strict deep drawing process such as a motor casing, the sliding of the metal mold during processing and the frictional heat generated by the metal plate cause the film formed on the resin-coated metal plate to be At the same time as grinding and peeling, the resin component in the film is softened and adheres black to the sliding surface of the product. The blackened product obtained by mixing the peeled film (resin component) and the zinc powder peeled off from the zinc plating layer and the stamping oil is adhered to the metal mold, and is transferred to the surface of the product to cause the blackening phenomenon.

Generally, it is estimated that the temperature of the mold during press working is raised to about 120 ° C, and this phenomenon is more remarkable when the softening point (softening temperature) of the resin component contained in the peeled film is 120 ° C or less.

Therefore, the urethane-based resin used in the resin composition for forming a film of the present invention preferably has a softening point of 120 ° C or higher.

Further, in order to reduce the blackening phenomenon, it is necessary to reduce the amount of film peeling during press working and to suppress adhesion to the product. For this reason, as the film property of the urethane urethane-based resin, the optimum sliding type durometer hardness (SW hardness) is 25 or more. In other words, by hardening the urethane-based resin, the hardness of the film formed on the metal surface can be improved, and damage to the film during sliding of the mold can be reduced, and the film itself can be hardened, so that the film can be suppressed. Metal mold attachment and effect on product transfer.

From such a viewpoint, the urethane urethane-based resin preferably has a softening point of 120° C. or higher and a sliding hardness meter hardness of 25 or more.

(1-3) cerium oxide particles

The resin composition for film formation used in the present invention is contained in an amount of 50 parts by mass or more, preferably 60 parts by mass or more and 70 parts by mass or less, based on 30 to 50 parts by mass of the urethane urethane resin. 65 parts by mass or less of cerium oxide particles (but the total amount of the urethane urethane resin component and the cerium oxide particles is 100 parts by mass).

The cerium oxide particles can impart not only corrosion resistance and coating properties to the obtained resin film, but also increase the hardness of the film and improve the deep drawability. When the content of the cerium oxide particles is less than 50 parts by mass, the deep drawability tends to decrease. On the other hand, when the content of cerium oxide exceeds 70 parts by mass, the film formability of the resin film is lowered, and the corrosion resistance tends to be lowered.

In order to maximize the effect of the above-described cerium oxide particles, the average particle diameter of the cerium oxide particles is preferably in the range of 4 to 20 nm. This is because the smaller the average particle diameter of the cerium oxide particles, the higher the corrosion resistance of the resin film. However, when the average particle diameter is less than about 4 nm, the effect of improving the corrosion resistance tends to be saturated, and the stability of the aqueous resin dispersion is lowered. It is easy to gel. On the other hand, when the average particle diameter of the cerium oxide particles exceeds 20 nm, the film formability of the resin film is lowered, and the corrosion resistance and the coating property tend to be lowered.

Further, as a method of measuring the average particle diameter of the cerium oxide particles, a Shears method (4 to 6 nm) or a BET method (4 to 20 nm) is preferably used.

As the cerium oxide particles which can be preferably used as the colloidal cerium oxide in the cerium oxide particles which can be used in the resin composition for forming a film of the present invention, for example, the best use of "Snodex (registered trademark)" "XS", "SS", "40", "N", "UP", etc. of the series (colloidal cerium oxide manufactured by Nissan Chemical Industries, Ltd.).

(1-4) decane coupling agent

The resin composition for film formation used in the present invention contains a decane coupling agent. The decane coupling agent not only contributes to improvement of corrosion resistance, deep drawing property, coating property, etc., but also contributes to the adhesion of the resin film formed on the metal plate and the metal plate.

The content of the decane coupling agent in the resin composition for forming a film is preferably 5 parts by mass or more, preferably 5 parts by mass or more, based on 100 parts by mass of the total of the urethane urethane resin (nonvolatile resin component) and the cerium oxide particles. 7 parts by mass or more and 25 parts by mass or less, more preferably 20 parts by mass or less. When the content of the decane coupling agent is too small, the reactivity of the urethane urethane resin and the cerium oxide particles is lowered, and the corrosion resistance, the coating property, the deep drawing property, and the like are lowered. On the other hand, when the content of the decane coupling agent is too large, a gel-like substance is formed to lower the stability of the aqueous resin dispersion to be described later, or an increase in the dose of the decane coupling which does not contribute to the reaction, or a metal plate and a metal plate. The adhesion of the formed resin film may be lowered.

As the above decane coupling agent, a decane coupling agent of the chemical formula (1) is preferably used.

In the above chemical formula (1), R ¹ is a glycidoxy group, R ² and R ³ are lower alkoxy groups, R ⁴ is a lower alkoxy group or a lower alkyl group, and X is a lower alkylene group. Here, "lower" means that the number of carbon atoms is from 1 to 5, and further preferably, the number of carbon atoms is from 1 to 3.

The coating property of the aqueous resin dispersion liquid and the corrosion resistance of the obtained surface-treated metal sheet are improved by containing the above-described decane coupling agent. The decane coupling agent having a glycidoxy group at the terminal represented by the above chemical formula (1) may, for example, be γ-glycidoxypropyltrimethoxydecane or γ-glycidoxypropylmethyldiethyl. Oxydecane, vinyl-tris(β-methoxyethoxy)decane, and the like. Since the decane coupling agent having a glycidoxy group has strong crosslinking reactivity with an urethane urethane resin, the resin film obtained by using a decane coupling agent having a glycidoxy group is strong, corrosion resistance and deep drawing. Increased processability.

(1-5) Other additives

In the present invention, in order to form a stronger film, cross-linking between polymer chains can be achieved by utilizing a chemical bond formed by a reaction between functional groups. The crosslinking agent used for the crosslinking between the polymer chains is not particularly limited as long as it is a crosslinking agent having two or more functional groups capable of reacting with a carboxyl group in one molecule, and is not particularly limited. Examples thereof include sorbitol polyglycidyl ether, (poly) glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, (poly). a polyglycidyl ether such as ethylene glycol glycidyl ether or a glycidyl group-containing crosslinking agent such as polyglycidylamine; 4,4-di(ethyleneimidocarbonylamino)diphenylmethane, N, N-hexamethylene-1,6-bis(1-aziridine carbenamide), N,N-diphenylmethane-4,4-bis(1-aziridine carbenamide), toluene II a bifunctional aziridine compound such as aziridine carbenamide; tri-1-indolylphosphine oxide, tris[1-(2-methyl)aziridine]phosphine oxide, trimethylolpropane tri吖-aziridinyl propionate), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, tetramethylpropane tetraaziridine propionate, etc. a trifunctional or higher aziridine compound or such a derivative or the like contains an aziridine group Crosslinking agents, such above may be used alone or in combination.

The crosslinking 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, and most preferably 15 parts by mass or less based on 100 parts by mass of the urethane urethane resin. use. When the amount of the crosslinking agent used is too small, the crosslinking effect by the chemical bond (the effect of improving the corrosion resistance and the deep drawing property through the formation of a strong film) is insufficient. On the other hand, if the amount is too large, the viscosity is increased and the resin is dispersed. The stability of the liquid sometimes decreases.

In addition, the resin film-forming composition may contain a lubricant in a range that does not lower the corrosion resistance, the deep drawability, or the like. Examples of the lubricant include solid lubricants such as polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax, carnauba wax, paraffin wax, montan wax, rice bran wax, Teflon (registered trademark) wax, carbon disulfide, and graphite. One or two or more kinds of these solid lubricants can be used.

(2) Adjustment of Resin Aqueous Dispersion and Method of Forming Resin Film

In the production of the surface-treated metal sheet (resin film) of the present invention, the resin aqueous dispersion obtained by dispersing the resin composition for forming a film in water or a solvent containing water as a main component is used. In the aqueous resin dispersion for use in the present invention, in order to improve the formability of the resin coating film and the physical properties of the obtained film, a diluent solvent, an anti-skinning agent, a flat agent, and the like may be contained within a range not inhibiting the object of the present invention. Defoamer, penetrant, emulsifier, filming aid, coloring pigment, tackifier and lubricant.

The method of adjusting the resinous dispersion liquid is not particularly limited, and a cerium oxide particle, a decane coupling agent, and a crosslinking agent used as needed may be added to the aqueous dispersion of the urethane urethane resin in a predetermined amount. Additives such as lubricants are available. The cerium oxide particles, the decane coupling agent, the lubricant, and the crosslinking agent may be added at any stage. After the decane coupling agent and the crosslinking agent are added, gelation occurs in order to avoid the crosslinking reaction, and it is preferably not heated. For example, the aqueous resin dispersion is preferably stored at 25 ° C or lower. Further, the viscosity of the aqueous resin dispersion liquid is not particularly limited, and an ideal viscosity can be appropriately employed depending on the formation method and the like.

The method of forming the resin film on the metal plate is not particularly limited, and a conventionally known coating method can be employed. For example, the above aqueous resin dispersion is applied to the metal by a roll coating method, a spray method, a curtain type flat coating method, or the like. One or both sides of the surface of the board can be heated and dried. The heating and drying temperature is not particularly limited, and when a crosslinking agent is used, the temperature at which the crosslinking agent to be used is subjected to a crosslinking reaction is preferably employed. When a polyethylene wax is used as the lubricant, if the wax maintains a spherical shape, the workability in the subsequent processing step is good. Therefore, in order not to damage the spherical shape, it is preferable to carry out heat drying in the range of the temperature of the metal plate of 70-130 degreeC. Further, when the temperature of the metal plate at the time of application of the aqueous resin dispersion is high, the components in the aqueous resin dispersion before the coating film are dried react with the metal plate, or the water is evaporated before drying to cause uneven appearance, and thus the resin is water-dispersed. The temperature of the metal plate at the time of liquid application is preferably 50 ° C or less.

Further, the above-mentioned methylimine cross-linking structure is a base which can be used for the neutralization of the (volatile) water and the resin component by the presence of a functional group capable of forming a cross-linking of the imine in the film when the resin film is formed. The ingredients are used to crosslink to form a reaction. Therefore, it is possible to form a cross-linking of the imine under the conditions described above regardless of the temperature.

The metal plate used in the present invention is not particularly limited, and an optimum galvanized steel sheet can be preferably used, for example, a melt-plated pure zinc steel plate, an alloyed hot-dip galvanized steel sheet, a galvanized-5% aluminum steel plate, or a galvanized-55% aluminum alloy. Steel plate, electroplated pure zinc steel plate, electroplated zinc-nickel steel plate, aluminum plate, titanium plate, etc. Further, before the formation of the resin film, the surface of the metal plate may be subjected to a treatment such as Co or Ni, a resist treatment, or a substrate treatment of various chromate-free and hexavalent chromate-free.

The amount (thickness) of the resin film deposited on the metal plate is preferably 0.05 g/m ² or more, more preferably 0.2 g/m ² or more and 1 g/m ² or less, and most preferably 0.7 g/m ² after drying. the following. If the amount of adhesion is too small, the corrosion resistance is lowered. On the other hand, when the amount of adhesion is too large, the blackening resistance tends to decrease.

In the FT-IR measurement, a peak derived from cross-linking of the imine is observed in the vicinity of 1660 cm ^-1 because a urethane bond which can observe a peak in the same region is contained in the resin film of the present invention. Therefore, it is difficult to distinguish them clearly by FT-IR. However, for example, when the FT-IR measurement is performed on a sample prepared under the same conditions using a resin containing a urethane bond but no cross-linking of a methylimine, it can be confirmed that the resin of the present invention is compared with the sample. The peak of the film was increased around 1660 cm ^-1 .

In addition, as described above, it is difficult to quantify the amount of the cross-linking of the imine in the resin film, but the amount of the cross-linking of the imine which is calculated, for example, from the amount of charge in the production of the urethane-based resin ( The theoretical value is preferably from 5 to 120 milliequivalents, more preferably from 10 to 90 milliequivalents, based on 100 g of the total of the polyurethane and the (meth)acrylic polymer.

The resin film of the surface-treated steel sheet of the present invention has high hardness. Specifically, the urethane urethane-based resin is preferably applied to a glass plate by a bar coater of #20 and dried at 0 to 105 ° C to have a sliding hardness of 30 or more. More preferably 35 or more, and most preferably 40 or more.

Further, the surface-treated metal plate of the present invention may be used as it is after the processing step according to the application, or may be subjected to electrophoretic coating, powder coating, screen printing or the like under the existing conditions.

[Examples]

The present invention is not limited by the following examples, but the present invention is not limited to the following examples, and modifications and embodiments within the scope of the invention are included in the scope of the invention. The evaluation methods employed in the examples are as follows.

(1) Corrosion resistance

The obtained surface-treated metal plate (resin coated steel plate) was subjected to a salt spray test of the flattened plate material according to JIS-Z2371 (11.1 neutral salt spray test), and the amount of white rust generated was evaluated in accordance with the following evaluation criteria. The time to reach 5% of the area of the flat sheet.

(evaluation standard)

◎: White rust is generated for more than 240 hours

○: White rust is generated for 120 hours or more to less than 240 hours.

△: White rust is generated for more than 72 hours - less than 120 hours

×: White rust is generated for less than 72 hours

(2) Deep drawing processability

A press-molded product was produced by using a 80-ton crank-type press apparatus (manufactured by Honda Engineering Co., Ltd., 80-ton crank press, see Fig. 1) for the obtained surface-treated metal sheet (resin-coated steel sheet), and the molded article was visually observed. The biteness of the sliding surface and the blackening phenomenon (blackening resistance) were evaluated.

<Stamping conditions>

‧Anti-wrinkle pressure=9.8N

‧Forming speed = 40SPM

‧particle high (bead hight)=3mm

‧Slot R(r4)=2mm

‧Mold R(r3)=0.5mm

‧Mold diameter: 51.640mm

‧ Punch diameter: 50.120mm

(Evaluation criteria for biting molds)

◎: The area of the portion where the mold is formed is less than 40% of the total.

○: The area of the portion where the bite is generated is 40% or more and less than 60% of the total.

△: The area of the portion where the bite is generated is 60% or more and less than 80% of the total.

×: The area of the portion where the mold is generated is 80% or more of the total.

(Evaluation criteria for blackening phenomenon)

◎: No blackening was observed on the sliding surface of the press-formed product (excellent)

○: Good (refer to Figure 2(a))

△: difference

×: very poor (refer to Figure 2(b))

(3) Paintability

A melamine alkyd-based paint ("AMIRATUKU (registered trademark) #1000" manufactured by Kansai Paint Co., Ltd.) was spray-coated on the obtained surface-treated metal plate (resin coated steel plate) and the film thickness after drying was about 20 μm at 130 After burning at ° C for 20 minutes, post-coating was carried out. Then, the test material was immersed in boiling water for 1 hour, taken out, and left at room temperature (25 ° C) for 1 hour, and then a 100 mm square 1 mm square was punched on the surface of the test material with a cutter to perform tape stripping. In the test (JIS K5600, the tape used is "Cellotape (registered trademark) No. 405" manufactured by Mitsubishi Corporation), and the coating film adhesion was evaluated according to the following four stages of evaluation criteria based on the remaining number of coating films.

(evaluation standard)

◎: Residual rate 95% or more

○: Residual rate 80% or more and less than 95%

△: Residual rate 70% or more and less than 80%

×: The residual rate is less than 70%

(4) Hardness Sliding hardness tester hardness

The aqueous dispersion of each resin obtained in the following production example was applied to a glass plate having a length of 200 mm and a width of 150 mm by a bar coater of #20 to prepare a sample for evaluation, and the sliding hardness of the resin film was measured in accordance with JIS K5400-1959. Hardness.

(5) Softening point of resin

In order to measure the softening point of the resin, a predetermined amount of the resin aqueous dispersion was placed in a Teflon dish, and dried in a dryer at 40 ° C, and the obtained resin solid matter was subjected to a thermomechanical analysis test under the following conditions.

‧Test method: thermomechanical analysis / needle insertion method (TMA)

‧Testing device: TMA/SS120 manufactured by Seiko Technology Co., Ltd.

‧Test conditions: Measurement temperature: room temperature to 250 ° C

Heating rate: 5 ° C / min

Measuring load: 5gf

Determination of gas environment: argon gas 100ml / min, in the air stream

[Preparation of Resin Water Dispersion] Production Example 1 Preparation of aqueous urethane-based resin dispersion (H-MDI-based acryl acrylate resin)

In a pressurized corresponding synthesis apparatus having a content of 1.0 kg of a stirrer, a heating heater, a thermometer, and a temperature controller, 24.3 g of dimer acid, trimethylolpropane, and diethyl ether were charged as a polyol component. Polyester polyol formed by diol ("TA22-636", manufactured by Hitachi Chemical Co., Ltd.), 3.89 g of 1,4-cyclohexanedimethanol, 22.52 g of dimethylolpropionic acid, 8.82 g of dihydroxyl Acetone (manufactured by Merck Ltd., manufactured by JAPAN) to which 370.01 g of butyl acrylate, 370.01 g of n-butyl methacrylate, 13.32 g of diacetone acrylamide, 13.32 g of methyl ethyl ketone, and 1.51 g of p-hydroxyanisole were added. The reaction solvent was 96.01 g, and stirred to uniformly disperse the entire system.

Then, after adjusting the above mixed solution of the polyol and the acrylic monomer to 20 ° C, 128.81 g of dicyclohexylmethane-4,4'-diisocyanate (H-MDI) was added thereto as an isocyanate component, and then 0.12 g of two was added. Tin butyl laurate. After the end of the heat generation, the reaction solution was heated to 90 to 95 ° C for 1 hour, and reacted for 2.5 hours. Then, the reaction solution was cooled to 50 ° C, and 96.01 g of the above reaction solvent containing an acrylic monomer was introduced into a synthesis apparatus, and stirred at 50 ° C for 1 hour to obtain a prepolymer containing an acrylic monomer. The isocyanate group (NCO) content (%) of the obtained prepolymer was 3.9% (theoretical value: 3.96%; NCO/OH ratio was 1.58).

250 g of the above prepolymer containing an acrylic monomer was heated to 50 ° C, and then 11.18 g of triethylamine was added to neutralize the carboxyl group. In the neutralized acrylic polymer-containing prepolymer, 45.64 g of an anionic surfactant ("Alscope TH-330" (27% active solution): Toho Chemical Industry Co., Ltd.) was introduced over 15 minutes. A mixture of 1.23 g of a water-soluble azo polymerization initiator ("VA-044", manufactured by Wako Pure Chemical Industries, Ltd.) was mixed with 358.94 g of ion-exchanged water, and it was confirmed that 72.54 g of ions were added after completion of heat generation. The aqueous solution of hydrazine obtained by diluting 80% hydrazine monohydrate 7.25 g was exchanged with water to carry out a chain extension reaction. After the completion of the addition of the aqueous solution, the mixture was stirred at 65 ° C for 60 minutes. Then, 0.1 g of "KS-530" (manufactured by Shin-Etsu Chemical Co., Ltd., a suds suppressor) was added to obtain a dispersion 1.

After 300.00 g of the above dispersion 1 was heated to 50 ° C, 152.04 g of a reaction solvent mixed with the above acrylic monomer and 14.02 g of ion-exchanged water were mixed with 1.49 g of water-soluble azo-based polymerization in the dispersion 1 for 45 minutes. The polymerization initiator aqueous solution obtained by the initiator ("VA-044", manufactured by Wako Pure Chemical Industries, Ltd.) was stirred at 55 to 60 ° C for 4 hours. Then, an aqueous solution obtained by dissolving 3.87 g of an aqueous solution of diammonium adipate in 7.17 g of ion-exchanged water was added thereto, and the mixture was stirred at 55 to 60 ° C for 3 hours, and then the reaction solution was cooled to obtain an urethane urethane system. Resin aqueous dispersion.

Production Example 2 Preparation of a Carbamate-Based Polyurethane Resin Aqueous Dispersion

In a synthesis apparatus having a stirrer, a heating heater, a thermometer, and a temperature controller of 0.8 L in content, 60 g of polytetramethylene ether glycol was charged as a polyol component (average molecular weight of 1000, Baotu Valley Chemistry) Industrial Co., Ltd.), 14 g of 1,4-cyclohexanedimethanol, and 20 g of dimethylolpropionic acid were added to 30.0 g of N-methylpyrrolidone as a reaction solvent. 104 g of toluene diisocyanate as an isocyanate component was added thereto, and the mixed solution was heated to 80 to 85 ° C and reacted for 5 hours. The obtained prepolymer had an NCO content of 8.9%.

Further, 16 g of triethylamine was added to the prepolymer, and the mixture was emulsified at 50 ° C for 4 hours to carry out a chain extension reaction to obtain a carboxyl group-containing aqueous polyurethane resin dispersion.

Production Example 3 Preparation of an aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer

In an autoclave having an emulsification apparatus having a stirring base, a heating heater, a thermometer, and a temperature controller of 0.8 L, 626 parts by mass of water and 160 parts by mass of an ethylene-acrylic acid copolymer (20% by mass of acrylic acid, molten) were added. Index (MI): 1300, mass average molecular weight (Mw): 20,000, acid value: 150, "Premercol (registered trademark) 5990I" manufactured by Tahoe Chemical Co., Ltd.), and also added with respect to the above ethylene-acrylic acid copolymer The carboxyl group was 0.6 equivalent of triethylamine and 0.15 equivalent of sodium hydroxide, and the mixture was stirred at a high speed in a gas atmosphere of 150 ° C and 5 Pa, and the reaction solution was cooled to 40 ° C to obtain an aqueous dispersion of an ethylene-acrylic acid copolymer.

Production Example 4 Preparation of an aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer (addition of a crosslinking agent)

In the aqueous dispersion, 4,4-di(ethyleneimidocarbonylamino) as a crosslinking agent is added in a ratio of 5 parts by mass based on 100 parts by mass of the nonvolatile resin component of the ethylene-acrylic acid copolymer. Diphenylmethane (Kemytide "(registered trademark) DZ-22E"", Japan Co., Ltd.).

Production Example 5 Preparation of Ethylene-Acrylic Copolymer Water-Based Dispersion

200.0 g of ethylene-acrylic acid copolymer ("Premercol 59901" made by Ceramic Chemical Co., Ltd." was placed in an autoclave equipped with an emulsifier equipped with a stirrer, a heating heater, a thermometer, and a temperature controller. ; monomer unit derived from acrylic acid: 20% by mass, melt index: 1300, weight average molecular weight: 20,000, acid value 150), 8.0 g of polymaleic acid aqueous solution ("Nonpole PMA-50W" manufactured by Nippon Oil & Fats Co., Ltd.) Molecular weight: about 1100, polystyrene equivalent, 50% by mass of solid content), 33.5 g of triethylamine (0.63 equivalent parts based on total carboxyl groups in the ethylene-acrylic acid copolymer), and 6.9 g of 48% aqueous NaOH solution (relative The total carboxyl group in the ethylene-acrylic acid copolymer was 0.15 equivalent parts, 3.5 g of tall oil fatty acid ("Hartol FA3" manufactured by Harima Chemical Co., Ltd.), 792.6 g of ion-exchanged water, and sealed at 150 ° C and 5 atm. After stirring at 500 rpm for 3 hours, the mixture was cooled to 30 ° C, and 10.4 g of a decane coupling agent ("TSL 8350" manufactured by Toshiba Organic Chemical Co., Ltd.) and 31.2 g of polycarbodiimide ("SV-02" manufactured by Nisshinbo Co., Ltd., weight average molecular weight: 2700) were added. Solid 40% of the product mass), 72.8 g of ion-exchanged water, stirred for 10 minutes to obtain an aqueous.

[Softening point of resin aqueous dispersion and hardness of sliding hardness tester] (Experimental Example 1)

The aqueous urethane-based resin aqueous dispersion obtained in the above Production Examples 1 to 3 and Production Example 5, the carboxyl group-containing polyurethane resin aqueous dispersion, and the ethylene-acrylic polymer resin aqueous dispersion, The softening point and the hardness of the sliding type hardness tester were measured, and the results are shown in Table 1.

[Preparation of a resin aqueous dispersion for film formation and preparation of a surface-treated metal sheet] (Experimental Example 2)

Aqueous urethane-based resin aqueous dispersion obtained in each of the above production examples, carboxyl group-containing polyurethane resin aqueous dispersion, carboxyl group-containing polyurethane resin aqueous dispersion, and ethylene-non In the mixed solution of the aqueous dispersion of the saturated carboxylic acid copolymer, cerium oxide particles ("SNOWTEX (registered trademark) XS" manufactured by Nissan Chemical Co., Ltd.) and an average particle diameter of 4 to 6 nm were added as shown in Table 2 And a total of 100 parts by mass of the non-volatile component, and 10 parts by mass of γ-glycidoxypropyltrimethoxydecane as a decane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added thereto. The aqueous dispersion of the resin for forming a film is adjusted.

The resin aqueous dispersion for film formation was applied to the surface of a plated pure zinc steel sheet by a deep draw roll, and the coating film was dried by heating at a sheet temperature of 90 ° C to obtain a resin film having an adhesion amount of 0.4 g/m ² . Surface treated metal plate (resin coated steel plate). The corrosion resistance and deep drawability of the obtained resin-coated steel sheet were evaluated. The results are shown together in Table 2. Further, as the electroplated pure zinc steel sheet, a plated pure zinc steel sheet (zinc adhesion amount: 20 g/m ² , thickness: 0.8 mm) which was not subjected to chromate treatment was used.

Further, in Table 2, AU represents a nonvolatile resin component of an aqueous urethane-based resin dispersion, PU represents a non-volatile resin component of a carboxyl group-containing aqueous polyurethane resin dispersion, and EC represents ethylene. - a non-volatile resin component of an aqueous dispersion of an unsaturated carboxylic acid copolymer.

Steel sheets No. 1 to No. 3 are metal sheets having a surface treated with a resin film formed of the aqueous urethane-based resin dispersion of Production Example 1. From the results of Table 2, it is understood that these steel sheets have excellent corrosion resistance and deep drawability.

On the other hand, in the steel sheets Nos. 4 to 6, the carboxyl group-containing urethane resin aqueous dispersion of Production Example 2 was used, and the steel sheets Nos. 7 to 9 were dispersed in the water-containing carboxyl group-containing urethane resin of Production Example 2. A mixture of the aqueous dispersion of the ethylene-unsaturated carboxylic acid polymer resin of Production Example 4. These steel sheets were inferior in blackening resistance as compared with the above-mentioned steel sheets Nos. 1 to 3. This is considered to be because the resin film does not contain an acrylic resin, and sufficient film strength is not obtained.

Further, in the steel sheets Nos. 10 to 12, the ethylene-unsaturated carboxylic acid polymer resin aqueous dispersion of Production Example 4 was used, and in the steel sheets Nos. 13 to 15, the ethylene-unsaturated carboxylic acid polymer resin aqueous dispersion of Production Example 5 was used. These steel sheets were inferior in blackening resistance as compared with the above-mentioned steel sheets Nos. 1 to 3. This is considered to be because the softening point of the resin film is low.

(Experimental Example 3)

The aqueous urethane-based resin dispersion obtained in the above Production Example 1 and the cerium oxide particles ("SNOWTEX (registered trademark) XS" manufactured by Nissan Chemical Co., Ltd., average particle diameter: 4 to 6 nm) were added as shown in Table 2. The composition is added in a total amount of 100 parts by mass in terms of a non-volatile component, and 10 parts by mass of γ-glycidoxypropyltrimethoxydecane as a decane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) is added thereto. ), the aqueous resin solution for forming a film is adjusted.

The resin aqueous solution for forming a film was applied onto the surface of a plated pure zinc steel sheet by a deep drawing roll, and the coating film was dried by heating at a sheet temperature of 90 ° C to obtain a surface treatment of a resin film having an adhesion amount of 0.4 g/m ² . Metal plate (resin coated steel plate). The corrosion resistance and deep drawability of the obtained resin-coated steel sheet were evaluated. The results are shown in Table 3. Further, as the electroplated pure zinc steel sheet, a plated pure zinc steel sheet (zinc adhesion amount: 20 g/m ² , thickness: 0.8 mm) which was not subjected to chromate treatment was used.

Steel sheets No. 15 to No. 19 are metal sheets having a surface treatment of a resin film obtained by using the aqueous urethane-based resin aqueous dispersion of Production Example 1, and the aqueous resin dispersion for forming a film contains 30 to 50 masses. (a non-volatile resin component) aqueous urethane-based resin aqueous dispersion and 50 to 70 parts by mass of cerium oxide particles, and the total amount thereof is 100 parts by mass, and is also 3 parts by mass with respect to the total amount of 100 parts by mass. The proportion of ～20 parts by mass contains a decane coupling agent. These steel sheets are excellent in corrosion resistance and deep drawability.

On the other hand, the steel sheets No. 10 to No. 14 are examples in which the amount of the urethane-based resin contained in the aqueous resin dispersion for forming a film is small, and the corrosion resistance is higher than that of the steel sheets of Nos. 15 to 19. Poor sex. Steel sheets No. 20 to No. 22 are examples in which the amount of the non-volatile resin component added is too large, and the blackening resistance is inferior to those of the steel sheets of Nos. 15 to 19.

(Experimental Example 4)

The aqueous urethane-based resin dispersion obtained above and the cerium oxide particles ("SNOWTEX (registered trademark) XS" manufactured by Nissan Chemical Co., Ltd., average particle diameter 4 to 6 nm) are urethane acrylate resins. The aqueous dispersion is added in an amount of 40 parts by mass of the nonvolatile resin component and 60 parts by mass of the cerium oxide particles, and 0 to 30 parts by mass of the decane coupling agent (γ-glycidyl) is added to 100 parts by mass of the total of the two. Oxypropyltrimethoxydecane, "KBM403" manufactured by Shin-Etsu Chemical Co., Ltd.), and an aqueous resin solution for forming a film was adjusted.

The resin aqueous solution for forming a film was applied onto the surface of a plated pure zinc steel sheet by a deep drawing roll, and the coating film was dried by heating at a sheet temperature of 90 ° C to obtain a surface treatment of a resin film having an adhesion amount of 0.4 g/m ² . Metal plate (resin coated steel plate).

The corrosion resistance, deep drawability, and paintability of the obtained resin-coated steel sheet were evaluated. The results are shown in Table 4. Further, as the electroplated pure zinc steel sheet, a plated pure zinc steel sheet (zinc adhesion amount: 20 g/m ² , thickness: 0.8 mm) which was not subjected to chromate treatment was used.

Steel plate No. 24 to No. 29 are metal sheets having a surface treatment of a resin film obtained by using an aqueous urethane-based resin dispersion, and the resin-forming resin aqueous liquid contains 30 to 50 parts by mass (nonvolatile) In the resin composition, the aqueous urethane-based resin aqueous liquid and the cerium oxide particles of 50 to 70 parts by mass are further contained in a ratio of 5 to 25 parts by mass based on 100 parts by mass of the total of the decane coupling agent. As is clear from Table 4, these steel sheets are excellent in corrosion resistance, deep drawability, and paintability.

On the other hand, the steel sheet No. 23 is an example in which the decane coupling agent is not contained, and the steel sheet No. 30 is an example in which the content of the decane coupling agent is more than 25 parts by mass, and any steel sheet is compared with the steel sheet of No. 24 to No. 29. The paintability is poor.

(Experimental Example 5)

40 parts by mass of the aqueous urethane-based resin dispersion obtained in the above Production Example 1 (in terms of non-volatile resin component) and cerium oxide particles having an average particle diameter of 4 to 100 nm ("SNOWTEX" (registered trademark of Nissan Chemical Co., Ltd.) 40 parts by mass of the mixture, and 10 parts by mass of a total of 100 parts by mass of a decane coupling agent (γ-glycidoxypropyltrimethoxydecane, "SKM403" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the total amount of the mixture. An aqueous resin solution for forming a film.

The resin aqueous solution for forming a film was applied onto the surface of a plated pure zinc steel sheet by a deep drawing roll, and the coating film was dried by heating at a sheet temperature of 90 ° C to obtain a surface treatment of a resin film having an adhesion amount of 0.4 g/m ² . Metal plate (resin coated steel plate). Further, as the electroplated pure zinc steel sheet, a plated pure zinc steel sheet (zinc adhesion amount: 20 g/m ² , thickness: 0.8 mm) which was not subjected to chromate treatment was used.

The corrosion resistance, deep drawability, and paintability of the obtained resin-coated steel sheet were evaluated. The results are shown in Table 5.

As is clear from the results of Table 5, by using the cerium oxide particles having an average particle diameter of 4 to 20 nm, a surface-treated metal sheet excellent in corrosion resistance, deep drawability, and paintability can be obtained.

(Experimental Example 6)

40 parts by mass of the aqueous urethane-based resin dispersion obtained in the above Production Example 1 (in terms of non-volatile resin component) and cerium oxide particles ("SNOWTEX (registered trademark) XS" manufactured by Nissan Chemical Co., Ltd., average 60 parts by mass of the particle diameter of 4 to 6 nm was mixed, and 10 parts by mass of each of the decane coupling agents shown in Table 6 was added to 100 parts by mass of the total of the two, and the aqueous resin solution for forming a film was adjusted.

The resin aqueous solution for forming a film was applied onto the surface of a plated pure zinc steel sheet by a deep drawing roll, and the coating film was dried by heating at a sheet temperature of 90 ° C to obtain a surface treatment of a resin film having an adhesion amount of 0.4 g/m ² . Metal plate (resin coated steel plate). The corrosion resistance, deep drawability, and paintability of the obtained resin-coated steel sheet were evaluated. The results are shown in Table 6. Further, as the electroplated pure zinc steel sheet, a plated pure zinc steel sheet (zinc adhesion amount: 20 g/m ² , thickness: 0.8 mm) which was not subjected to chromate treatment was used.

As a result of the above-mentioned Table 6, it is understood that the resin solution for forming a film (steel plates No. 35 to 37) can be stably ensured by using a decane coupling agent having a glycidoxy group at the terminal as a decane coupling agent. Further, the steel sheets of Nos. 35 to 37 described above are excellent in corrosion resistance, deep drawability, and paintability.

(Experiment 7)

40 parts by mass (in terms of non-volatile resin component) of the aqueous urethane-based resin dispersion obtained in the above Production Example 1 and cerium oxide particles ("SNOWTEX (registered trademark) XS" manufactured by Nissan Chemical Co., Ltd. 4 to 6 nm), 60 parts by mass of the mixture, and 10 parts by mass of a total of 100 parts by mass of a decane coupling agent (γ-glycidoxypropyltrimethoxydecane, "SKM403" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the total amount of the mixture. An aqueous resin solution for forming a film.

The resin aqueous solution for forming a film was applied onto the surface of a plated pure zinc steel sheet by a deep drawing roll, and the coating film was dried by heating at a plate temperature of 90 ° C to obtain a resin film having an adhesion amount of 0.05 to 2.0 g/m ² . Surface treated metal plate (resin coated steel plate).

The corrosion resistance, deep drawability, and paintability of the obtained resin-coated steel sheet were evaluated. The results are shown in Table 7. Further, as the electroplated pure zinc steel sheet, a plated pure zinc steel sheet (zinc adhesion amount: 20 g/m ² , thickness: 0.8 mm) which was not subjected to chromate treatment was used.

As is clear from the results of Table 7, the corrosion resistance, the deep drawing property, and the coating property of the surface metal plate can be improved by setting the amount of the resin film deposited on the surface of the metal plate to be in the range of 0.05 to 1 g/m ² .

The surface-treated metal sheet of the present invention is excellent in corrosion resistance, deep drawing processability, and coating property, and is therefore suitable for use in automobiles, home electric appliances, and building materials, such as an acoustic chassis, a computer case, a motor case, and a pulley. Pumping products.

1‧‧‧上模

2‧‧‧Down

3‧‧‧Mode

4‧‧‧ Punch Trail

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Fig. 1 is a view showing a processing apparatus used for evaluation of deep drawability.

Fig. 2 is a view showing the appearance of a sliding portion of a steel sheet after deep drawing.

Claims (7)

A surface-treated metal plate characterized by having a surface treated metal plate on a surface of a metal plate, wherein the resin film contains 30 to 50 parts by mass of an urethane urethane resin and 50 to 70 parts by mass. The cerium oxide particles having an average particle diameter of 4 to 20 nm, and a total of 100 parts by mass, and 5 to 25 parts by weight based on 100 parts by mass of the total of the urethane urethane resin and the cerium oxide particles. A resin composition for forming a film of a decane coupling agent in a ratio by mass is formed. The metal sheet for surface treatment according to the first aspect of the invention, wherein the urethane-based resin contains: a polyisocyanate, a polyhydric alcohol, and a dihydroxyalkanoic acid as a raw material, and these are 3 to 80 parts by mass in total. The polyurethane obtained from the urethane prepolymer and the (meth)acrylic polymer obtained from 10 to 97 parts by mass of the (meth)acrylic monomer. The surface treated metal sheet according to the first aspect of the invention, wherein the urethane urethane resin has a carbonyl group in a structure of at least one of a polyurethane and a (meth)acrylic polymer; At least one of the bases. The metal sheet for surface treatment according to the first aspect of the invention, wherein the urethane urethane resin has a softening point of 120 ° C or higher and a Shard Rocker hardness of 25 or more. The surface treated metal sheet of claim 1, wherein the resin film has a methylimine crosslinked structure. The surface treated metal sheet according to the first aspect of the invention, wherein the decane coupling agent has a structure represented by the following chemical formula (1), (In the above chemical formula (1), R ¹ is a glycidoxy group, R ² and R ³ are a lower alkoxy group, R ⁴ is a lower alkoxy group or a lower alkyl group, and an X-based lower alkylene group). The surface-treated metal sheet according to any one of the first to fifth aspect, wherein the amount of the resin film deposited is 0.05 to 1 g/m ² .