JP2013108126A - Surface treated metal sheet excellent in corrosion resistance and conductivity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treated metal sheet further improved in corrosion resistance, alkali degreasing resistance, conductivity, coating properties, abrasion resistance, and tape peeling resistance.SOLUTION: The surface treated metal sheet includes a metal sheet, and a resin film obtained from a resin aqueous liquid, and formed on at least one side of the metal sheet. The resin aqueous liquid contains a non-volatile resin component, and silica particles, wherein, as the non-volatile resin component, there are contained a non-volatile resin component (EC) of an ethylene/unsaturated carboxylic acid copolymer aqueous liquid, and a non-volatile resin component (PU) of a carboxyl group containing polyurethane resin aqueous liquid, at a mass ratio of EC:PU=90:10 to 40:60, and wherein there are further contained 5 to 20 pts.mass of a silane coupling agent to 100 pts.mass of the total of the non-volatile resin component and the silica particles, and 1 to 14 pts.mass of alkoxysilane.

Description

  The present invention relates to a surface-treated metal plate, and more specifically, corrosion resistance, alkali degreasing resistance, conductivity, paintability (coating film adhesion), and abrasion resistance used for automobiles, home appliances, building materials, and the like. The present invention relates to a surface-treated metal plate having excellent tape peel resistance.

  In addition to zinc-based plated steel sheets such as electrogalvanized steel sheets and hot-dip galvanized steel sheets, materials used for automobiles, home appliances, building materials, etc., as well as galvanized materials for the purpose of further improving corrosion resistance and fingerprint resistance Steel plates that have been subjected to chromate treatment or zinc phosphate treatment on steel plates have been often used. In addition, a resin-coated steel sheet in which an organic resin film is formed on a surface-treated steel sheet that has been chromated for the purpose of further improving corrosion resistance, paintability, and workability has been proposed.

  In recent years, the demand for steel sheets not subjected to chromate treatment has been increased from the viewpoint of global environmental conservation, and various steel sheets having an organic resin film formed without containing hexavalent chromium have been proposed. However, since it is very difficult to ensure corrosion resistance without chromate treatment, it is very difficult to ensure sufficient corrosion resistance with a thin film.

  On the other hand, the demand for a material having excellent conductivity is increasing in order to cope with antistatic properties and electromagnetic wave shielding properties for steel plates used with higher performance of electrical equipment. Concerning conductivity, when a film is applied on a galvanized steel sheet, it is necessary to reduce the amount of the film to ensure conductivity. However, in a product in which an organic resin film is provided on a galvanized steel sheet, if the amount of the organic resin film is low, the corrosion resistance and workability deteriorate, so that properties other than conductivity are insufficient and are not suitable for practical use.

  In order to solve the above-mentioned problems of such resin-coated steel sheets, as the resin film, a lubricating steel sheet having a film having an inorganic polymer compound and a solid lubricant and a film having an aqueous resin were further formed. Lubricated steel sheets have been proposed. However, from the viewpoint of global environmental conservation, cleaning by alkaline degreasing has increased in place of organic solvent-based degreasing agents such as trichlorethylene and methylene chloride that have been used in the washing process after press processing. Since the alkali degreasing resistance is insufficient, it is not suitable for practical use. For example, Patent Document 1 also proposes a resin film containing silica and a silane coupling agent in an aqueous resin solution.

JP 2006-43913 A

However, in the surface-treated metal plate described in Patent Document 1, the polyurethane resin content in the nonvolatile resin component constituting the resin film is as high as 67 to 90% by mass. Therefore, it cannot be said that it has sufficient alkali degreasing resistance in a usage mode in which the alkaline degreasing conditions are severe, and a surface-treated metal plate that is more excellent in alkali degreasing resistance is desired.
The present invention has been made in view of the above circumstances, and provides a surface-treated metal plate further improved in corrosion resistance, alkali degreasing resistance, conductivity, paintability, abrasion resistance, and tape peel resistance. With the goal.

The surface-treated metal plate of the present invention capable of solving the above problems is a surface-treated metal plate comprising a metal plate and a resin film obtained from a resin aqueous liquid formed on at least one surface of the metal plate, The aqueous resin liquid contains 20 to 45 parts by mass of a nonvolatile resin component and 55 to 80 parts by mass of silica particles having an average particle diameter of 4 to 20 nm so that the total amount becomes 100 parts by mass, and the nonvolatile resin As a component, the non-volatile resin component (EC) of the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion and the non-volatile resin component (PU) of the carboxyl group-containing polyurethane resin aqueous liquid are contained. It is EC: PU = 90: 10-40: 60 by mass ratio, Furthermore, the silane coupling body represented by Formula (a) with respect to a total of 100 mass parts of the said non-volatile resin component and a silica particle. Agent and 5 to 20 parts by weight, characterized in that it contains 1 to 14 parts by weight of an alkoxysilane of the formula (b). The alkoxysilane represented by the formula (b) is preferably hexyltrimethoxysilane. The adhesion amount of the resin film is preferably 0.05 to 1 g / m ² .

［式（ａ）中、Ｒ¹、Ｒ²はアルコキシ基、Ｒ³はアルコキシ基又は炭素数１〜４のアルキル基、Ｘは炭素数１〜５のアルキレン基を表す。］

[In Formula (a), R ¹ and R ² represent an alkoxy group, R ³ represents an alkoxy group or an alkyl group having 1 to 4 carbon atoms, and X represents an alkylene group having 1 to 5 carbon atoms. ]

［式（ｂ）中、Ｒ⁴、Ｒ⁵、Ｒ⁶はアルコキシ基、Ｒ⁷は炭素数５〜７のアルキル基を表す。］

[In the formula (b), R ⁴ , R ⁵ and R ⁶ represent an alkoxy group, and R ⁷ represents an alkyl group having 5 to ⁷ carbon atoms. ]

  In the surface-treated metal plate of the present invention, the resin film contains a predetermined amount of an ethylene-unsaturated carboxylic acid copolymer and a carboxyl group-containing polyurethane resin as resin components, and silica particles, and a specific silane coupling agent And an aqueous resin liquid containing a specific alkoxysilane. In particular, the ethylene-unsaturated carboxylic acid copolymer content in the resin component is high. Therefore, the surface-treated metal plate of the present invention is excellent in corrosion resistance, conductivity, paintability, abrasion resistance, tape peel resistance, and alkali degreasing resistance.

The surface-treated metal plate of the present invention includes a metal plate and a resin film obtained from an aqueous resin liquid formed on at least one surface of the metal plate.
The aqueous resin liquid used in the present invention contains 20 to 45 parts by mass of the nonvolatile resin component and 55 to 80 parts by mass of silica particles having an average particle diameter of 4 to 20 nm so that the total amount becomes 100 parts by mass. Yes. Here, the non-volatile resin component includes a non-volatile resin component (EC) of an ethylene-unsaturated carboxylic acid copolymer aqueous dispersion and a non-volatile resin component (PU) of a carboxyl group-containing polyurethane resin aqueous liquid. And these compounding ratios are adjusted to EC: PU = 90: 10-40: 60 by mass ratio. Further, the aqueous resin liquid is a silane coupling agent represented by the formula (a) (hereinafter, “silane coupling agent (a)”) with respect to 100 parts by mass in total of the nonvolatile resin component and the silica particles. 5 to 20 parts by mass and 1 to 14 parts by mass of an alkoxysilane represented by the formula (b) (hereinafter referred to as “alkoxysilane (b)”).
As described above, the content of the nonvolatile resin and the silica particles, the kind of the nonvolatile resin, and the specific silane coupling agent (a) and alkoxy for increasing the affinity between the nonvolatile resin and the silica particles By forming a resin film using an aqueous resin liquid in which the content of silane (b) is highly controlled, the corrosion resistance, conductivity, paintability, abrasion resistance, and tape peel resistance are excellent, and A surface-treated metal plate having excellent alkali degreasing resistance can be obtained.
Hereinafter, the present invention will be described in detail.

1. Nonvolatile Resin Component The aqueous resin liquid contains an ethylene-unsaturated carboxylic acid copolymer and a carboxyl group-containing polyurethane resin as a nonvolatile resin component.
In the present invention, by using an ethylene-unsaturated carboxylic acid copolymer and a carboxyl group-containing polyurethane resin in combination, a surface-treated metal plate excellent in paintability, corrosion resistance, abrasion resistance, and alkali degreasing resistance can be obtained. . The ethylene-unsaturated carboxylic acid copolymer and the carboxyl group-containing polyurethane resin are blended in the resin aqueous liquid as an ethylene-unsaturated carboxylic acid copolymer aqueous dispersion and a carboxyl group-containing polyurethane resin aqueous liquid, respectively.

1-1. Ethylene-unsaturated carboxylic acid copolymer aqueous dispersion The ethylene-unsaturated carboxylic acid copolymer aqueous dispersion used in the present invention will be described.
The ethylene-unsaturated carboxylic acid copolymer aqueous dispersion used in the present invention is not particularly limited as long as it is a liquid in which an ethylene-unsaturated carboxylic acid copolymer is dispersed in an aqueous medium. The aqueous medium may contain a trace amount of a hydrophilic solvent such as alcohol, N-methylpyrrolidone, and acetone in addition to water.

  The ethylene-unsaturated carboxylic acid copolymer is a copolymer of ethylene and an ethylenically unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, itaconic acid, and the like. A copolymer can be obtained by polymerization using a legal method or the like. The copolymer is most preferably random, but may be a block copolymer or a copolymer grafted with an unsaturated carboxylic acid moiety. As the unsaturated carboxylic acid, (meth) acrylic acid is suitable. Further, an olefin monomer such as propylene or 1-butene may be used instead of a part of ethylene. In this case, the content of olefin monomers other than ethylene is preferably 10% by mass or less. Furthermore, other known vinyl monomers may be partially copolymerized (about 10% by mass or less) as long as the object of the present invention is not impaired.

  The ethylene-unsaturated carboxylic acid copolymer is preferably one in which 10 to 40% by mass of an unsaturated carboxylic acid component is copolymerized when the total amount of monomers is 100% by mass. When the unsaturated carboxylic acid is 10% by mass or more, the number of carboxyl groups serving as a base point for intermolecular association by ion clusters or a cross-linking point with a crosslinking agent increases. Therefore, the film strength effect is improved, the corrosion resistance after the degreasing process is improved, and the emulsion stability of the aqueous dispersion is also improved. A more preferable lower limit of the unsaturated carboxylic acid is 15% by mass. On the other hand, if unsaturated carboxylic acid is 40 mass% or less, the corrosion resistance and water resistance of a resin film will improve further, and the corrosion resistance after an alkali degreasing process will become more favorable. A more preferred upper limit is 25% by mass.

The ethylene-unsaturated carboxylic acid copolymer used in the present invention has a carboxyl group, and an aqueous dispersion can be obtained by neutralizing the carboxyl group with an organic base or metal ion.
It is preferable to use an amine having a boiling point of 100 ° C. or lower as the organic base. Amines having a boiling point exceeding 100 ° C. tend to remain in the resin film on the metal plate when the resin aqueous solution is dried, and the water absorption of the resin film increases, resulting in a decrease in corrosion resistance. Accordingly, it is preferable that the aqueous ethylene-unsaturated carboxylic acid copolymer dispersion used in the present invention does not contain amines having a boiling point of more than 100 ° C. Moreover, since the addition effect of ammonia was not recognized, it is preferable that ammonia is not contained. As the boiling point, a boiling point under atmospheric pressure is adopted.

  Specific examples of the amine having a boiling point of 100 ° C. or lower include tertiary amines such as triethylamine, N, N-dimethylbutylamine, N, N-dimethylallylamine, N-methylpyrrolidine, tetramethyldiaminomethane, and trimethylamine; N-methylethylamine Secondary amines such as isopropylamine, diisopropylamine and diethylamine; primary amines such as propylamine, t-butylamine, sec-butylamine, isobutylamine, 1,2-dibutylpropylamine and 3-pentylamine; Or 2 or more types can be mixed and used. Of these, tertiary amines are preferred, and triethylamine is the most preferred.

  The amount of the amine having a boiling point of 100 ° C. or less may be in the range of 0.2 to 0.8 mol (20 to 80 mol%) with respect to 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. preferable. This is because the corrosion resistance is good within this range. If the amine having a boiling point of 100 ° C. or less is 0.2 mol or more, it is considered that the particle size of the resin particles of the aqueous dispersion becomes small and the above effect is improved. Moreover, if it is 0.8 mol or less, it will suppress that an aqueous dispersion will thicken and gelatinize. The upper limit of the amount of the amine is more preferably 0.6 mol, still more preferably 0.5 mol, and the lower limit of the amount of the amine is more preferably 0.3 mol.

  In the present invention, it is also preferable to use a monovalent metal ion for neutralization in addition to the amine having a boiling point of 100 ° C. or less. Effective for improving solvent resistance and film hardness. The monovalent metal compound preferably contains one or more metals selected from sodium, potassium, and lithium, and a hydroxide, carbonate, or oxide of these metals is preferable. Among these, NaOH, KOH, LiOH and the like are preferable, and NaOH has the best performance and is preferable.

  The amount of the monovalent metal compound is such that the amount of the monovalent metal contained is 0.02 to 0.4 mol (2 mol per mol of carboxyl group in the ethylene-unsaturated carboxylic acid copolymer). It is preferable to be in the range of ˜40 mol%. If the amount of the metal is 0.02 mol or more, the emulsion stability becomes better, and if it is 0.4 mol or less, the hygroscopicity (especially with respect to the alkaline solution) of the resulting resin film is reduced, and degreasing. Corrosion resistance after the process is further improved. A more preferable lower limit of the metal amount is 0.03 mol, and a more preferable lower limit is 0.1 mol. A more preferable upper limit of the metal amount is 0.3 mol, and a still more preferable upper limit is 0.2 mol.

  The preferred ranges of the respective amounts of the amine having a boiling point of 100 ° C. or less and the monovalent metal compound are as described above, and these all neutralize the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. And used to make it aqueous. Accordingly, if the total amount (neutralization amount) is too large, the viscosity of the aqueous dispersion may rapidly increase and solidify, and excessive alkali may cause corrosion resistance deterioration or volatilization. For this reason, a large amount of energy is required, which is not preferable. However, if the neutralization amount is too small, the emulsifiability is inferior, which is not preferable. Therefore, the total amount of the amine having a boiling point of 100 ° C. or less and the monovalent metal is in the range of 0.3 to 1.0 mol with respect to 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. It is preferable.

  The aqueous dispersion of ethylene-unsaturated carboxylic acid copolymer used in the present invention has an average particle diameter of 5 to 50 nm by emulsifying an amine having a boiling point of 100 ° C. or less and a monovalent metal ion in combination. What is dispersed in an aqueous medium in the form of small fine particles (oil droplets) is obtained. For this reason, it is presumed that the film forming property of the obtained resin film, the adhesion to the metal plate, the densification of the film are achieved, and the corrosion resistance is improved. The aqueous medium may contain a hydrophilic solvent such as alcohol or ether in addition to water. The particle diameter of the resin particles in the aqueous dispersion can be measured by a laser diffraction method using, for example, a light scattering photometer (manufactured by Otsuka Electronics Co., Ltd.).

  In the neutralization step (aqueous step) of an ethylene-unsaturated carboxylic acid copolymer with an amine having a boiling point of 100 ° C. or less and a monovalent metal ion, an amine having a boiling point of 100 ° C. or less and a monovalent metal compound are simultaneously It is desirable to add to the polymer or to add an amine having a boiling point of 100 ° C. or lower first. The reason is not clear, but if an amine having a boiling point of 100 ° C. or lower is added later, the effect of improving the corrosion resistance may be insufficient.

  As a method for preparing an aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer used in the present invention, an ethylene-unsaturated carboxylic acid copolymer is put together with an aqueous medium into, for example, a homogenizer device and the like. Under heating at ˜250 ° C., an amine having a boiling point of 100 ° C. or less and a monovalent metal compound is appropriately added in the form of an aqueous solution or the like (an amine having a boiling point of 100 ° C. or less is added first, or a boiling point of 100 ° C. or less Amine and monovalent metal compound are added almost simultaneously) and stirred with high shear force.

1-2. Carboxyl group-containing polyurethane resin aqueous liquid The carboxyl group-containing polyurethane resin aqueous liquid used in the present invention is an aqueous dispersion in which a carboxyl group-containing polyurethane resin is dispersed in an aqueous medium, or the carboxyl group-containing polyurethane resin is an aqueous medium. Any dissolved aqueous solution can be used. The aqueous medium may contain a trace amount of a hydrophilic solvent such as alcohol, N-methylpyrrolidone, and acetone in addition to water.

The carboxyl group-containing polyurethane resin is preferably obtained by chain extension reaction of a urethane prepolymer with a chain extender.
The urethane prepolymer is obtained, for example, by reacting a polyisocyanate component and a polyol component described later. As the polyisocyanate component constituting the urethane prepolymer, at least one polyisocyanate selected from the group consisting of tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and dicyclohexylmethane diisocyanate (hydrogenated MDI) is used. It is preferable. By using such polyisocyanate, a resin film excellent in corrosion resistance and stability of reaction control can be obtained.

  In addition to the polyisocyanate, other polyisocyanates can be used as long as the corrosion resistance and reaction control stability are not lowered. Examples of the polyisocyanate other than the polyisocyanate component include tetramethylene diisocyanate, hexamethylene diisocyanate, dodecane methylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, and phenylene diisocyanate. The above polyisocyanates may be used alone or in admixture of at least two kinds. When using other polyisocyanate, the content of the polyisocyanate component (TDI, MDI, hydrogenated MDI) is desirably 70% by mass or more of the total polyisocyanate component. When the content of these polyisocyanate components is 70% by mass or more, the corrosion resistance and the stability of reaction control are further improved.

  As the polyol component constituting the urethane prepolymer, it is preferable to use all three types of polyols, 1,4-cyclohexanedimethanol, polyether polyol, and polyol having a carboxyl group, more preferably three types. All are diols. This is because by using such a polyol component, a resin film having excellent corrosion resistance and slidability can be obtained. Moreover, the antirust effect of the polyurethane resin obtained can be heightened by using 1, 4- cyclohexane dimethanol as a polyol component.

  The polyether polyol is not particularly limited as long as it has at least two hydroxyl groups in the molecular chain and the main skeleton is composed of alkylene oxide units. For example, polyoxyethylene glycol (simply, Sometimes referred to as "polyethylene glycol"), polyoxypropylene glycol (sometimes simply referred to as "polypropylene glycol"), polyoxytetramethylene glycol (simply "polytetramethylene glycol" or "polytetramethylene") May be referred to as “ether glycol”), and commercially available ones may be used. Among the polyether polyols, it is preferable to use polyoxypropylene glycol or polytetramethylene ether glycol. The number of functional groups of the polyether polyol is not particularly limited as long as it is at least 2 or more, and may be, for example, trifunctional or tetrafunctional or more polyfunctional.

  The polyether polyol can be obtained, for example, by adding an alkylene oxide such as ethylene oxide or propylene oxide using a compound having active hydrogen as an initiator. Examples of the compound having active hydrogen include diols such as propylene glycol and ethylene glycol; triols such as glycerin, trimethylolpropane, hexanetriol, and triethanolamine; tetraols such as diglycerin and pentaerythritol; and others, sorbitol, Examples thereof include sucrose and phosphoric acid. At this time, if a diol is used as an initiator to be used, a bifunctional polyether polyol can be obtained, and if a triol is used, a trifunctional polyether polyol can be obtained. Polyoxytetramethylene glycol is obtained, for example, by ring-opening polymerization of tetrahydrofuran.

  As the polyether polyol, for example, a commercially available product having a number average molecular weight of about 400 to 4000 is preferably used. If the number average molecular weight is about 400 or more, the flexibility of the resin film is improved. If the number average molecular weight is 4000 or less, it can be suppressed that the resin film becomes too soft. The number average molecular weight can be determined by measuring the OH value (hydroxyl value).

  In the present invention, it is also a preferred embodiment that the mass ratio of 1,4-cyclohexanedimethanol and polyether polyol is 1,4-cyclohexanedimethanol: polyether polyol = 1: 1 to 1:19. It is because the rust prevention effect of the obtained polyurethane resin film can be further enhanced by using a fixed ratio of 1,4-cyclohexanedimethanol having a rust prevention effect.

  The polyol having a carboxyl group is not particularly limited as long as it has at least one carboxyl group and at least two hydroxyl groups. For example, dimethylolpropionic acid, dimethylolbutanoic acid, dihydroxypropionic acid, dihydroxy And succinic acid. What is necessary is just to adjust the usage-amount of the polyol which has a carboxyl group according to the desired hydroxyl value.

  In addition to the three types of polyol components, other polyols can be used within a range that does not lower the corrosion resistance. In this case, the content of the three types of polyol components is desirably 70% by mass or more of the total polyol components. When the content of the three kinds of polyol components is 70% by mass or more, the corrosion resistance is further improved. The polyol other than the above-described three types of polyol components is not particularly limited as long as it has a plurality of hydroxyl groups, and examples thereof include a low molecular weight polyol and a high molecular weight polyol.

The low molecular weight polyol is a polyol having an average molecular weight of about 500 or less. For example, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6- Diols such as hexanediol; and triols such as glycerin, trimethylolpropane, and hexanetriol.
The high molecular weight polyol is a polyol having an average molecular weight exceeding about 500. For example, a condensed polyester polyol such as polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexamethylene adipate (PHMA); poly-ε- Examples include lactone polyester polyols such as caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols.

  The chain extender for chain extending reaction of the urethane prepolymer described above is not particularly limited, and examples thereof include polyamines, low molecular weight polyols, and alkanolamines. As the low molecular weight polyol, the same ones as described above can be used. Examples of the polyamine include aliphatic polyamines such as ethylenediamine, propylenediamine, and hexamethylenediamine; aromatic polyamines such as tolylenediamine, xylylenediamine, and diaminodiphenylmethane; alicyclic polyamines such as diaminocyclohexylmethane, piperazine, and isophoronediamine; Examples include hydrazines such as hydrazine, succinic dihydrazide, adipic dihydrazide, and phthalic dihydrazide. Among these, it is preferable to use ethylenediamine and / or hydrazine as a chain extender component. Examples of the alkanolamine include diethanolamine and monoethanolamine.

  A well-known method can be employ | adopted for preparation of the aqueous liquid of the carboxyl group-containing polyurethane resin used by this invention. For example, a method in which the carboxyl group of a carboxyl group-containing urethane prepolymer is neutralized with a base and emulsified and dispersed in an aqueous medium to cause chain extension reaction; a carboxyl group-containing polyurethane resin is emulsified with high shear force in the presence of an emulsifier There is a method of dispersing and chain extending reaction; Hereinafter, based on a method of neutralizing the carboxyl group of the carboxyl group-containing urethane prepolymer with a base and emulsifying and dispersing it in water, a method for preparing an aqueous liquid of a polyurethane resin will be described, but the present invention is limited to such a method. It is not something.

  First, a relatively low molecular weight carboxyl group-containing isocyanate group-terminated urethane prepolymer is prepared by using the above-described polyisocyanate and the above-described polyol so that the isocyanate group becomes excessive in the NCO / OH ratio. Although the temperature which synthesize | combines a urethane prepolymer is not specifically limited, It can synthesize | combine at the temperature of 50-200 degreeC. Moreover, a well-known catalyst can be used for the synthesis | combination of a urethane prepolymer. Examples of the catalyst include monoamines such as triethylamine and N, N-dimethylcyclohexylamine; N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N ″, N ″ -pentamethyl Polyamines such as diethylenetriamine; cyclic diamines such as 1,8-diazabicyclo [5.4.0] -7-undecene (DBU) and triethylenediamine; tin-based catalysts such as dibutyltin dilaurate and dibutyltin diacetate It is done.

  In synthesizing the urethane prepolymer, a one-shot method may be adopted, or a prepolymer method may be adopted. The one-shot method is a method in which polyisocyanate and polyol are reacted together, and the prepolymer method is a method in which polyisocyanate and polyol are reacted in multiple stages. For example, once a low to medium molecular weight urethane prepolymer is reacted. This is a method of further increasing the molecular weight after synthesizing the polymer.

  In the present invention, for example, an embodiment in which polyisocyanate and all of the above three types of polyol are reacted together; first, polyisocyanate and the above three types of polyol components are first reacted with polyether polyol, and then 1 , 4-cyclohexanedimethanol, and a polyol having a carboxyl group are further reacted; among the polyol components, first, the polyether polyol and 1,4-cyclohexanedimethanol are reacted, and then the carboxyl group is converted. The urethane prepolymer may be synthesized by appropriately selecting the mode in which the polyol having the reaction is made.

  In preparing the carboxyl group-containing isocyanate group-terminated urethane prepolymer, it is also a preferred embodiment to use a solvent from the viewpoint of adjusting the viscosity and improving the emulsifying dispersibility of the prepolymer. As the solvent, it is preferable to use a solvent that is inert to the isocyanate group and has a relatively high hydrophilicity. For example, N-methylpyrrolidone, acetone, ethyl acetate, methyl ethyl ketone, N, N-dimethylformamide Etc., preferably N-methylpyrrolidone is used. This is because N-methylpyrrolidone is highly soluble in a polyol having a carboxyl group and can uniformly carry out a reaction for preparing an isocyanate group-terminated urethane prepolymer. In addition, reaction of a urethane prepolymer can obtain | require a reaction rate by calculating | requiring an isocyanate group density | concentration by the dibutylamine titration method, for example.

  After completion of the urethane prepolymer reaction, the obtained carboxyl group-containing isocyanate group-terminated urethane prepolymer can be emulsified and dispersed in water by neutralization with a base. The neutralizing agent is not particularly limited, but ammonia; tertiary amines such as triethylamine and triethanolamine; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide can be used. Preferably, triethylamine is used.

  After emulsifying and dispersing the carboxyl group-containing isocyanate group-terminated urethane prepolymer, a chain extension reaction can be carried out in water using a chain extender such as polymian. The chain extension reaction can be appropriately performed before emulsification dispersion, simultaneously with emulsification dispersion, or after emulsification dispersion, depending on the reactivity of the chain extender used.

  The acid value of the carboxyl group-containing polyurethane resin used in the present invention is preferably 10 mgKOH / g or more and 60 mgKOH / g or less. This is because when the acid value is less than 10 mgKOH / g, the stability of the aqueous polyurethane resin dispersion is lowered. Moreover, when an acid value exceeds 60 mgKOH / g, there exists a tendency for the corrosion resistance of the resin film obtained to fall. The acid value is measured according to JIS-K0070.

1-3. Compounding amount of resin component The resin aqueous liquid used in the present invention is a total of the nonvolatile resin component of the above-described aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer and the aqueous carboxyl group-containing polyurethane resin and silica particles described later. When the amount is 100 parts by mass, the content of the nonvolatile resin component is 20 parts by mass or more, more preferably 25 parts by mass or more, and 45 parts by mass or less, more preferably 35 parts by mass or less. If the amount of the nonvolatile resin component is too small, the corrosion resistance, alkali degreasing resistance, and paintability tend to deteriorate. On the other hand, if the amount of the non-volatile resin component is too large, abrasion resistance, tape peel resistance, and conductivity tend to decrease.

  Here, the non-volatile resin component of the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion is the above-described ethylene-unsaturated carboxylic acid copolymer, and the non-volatile resin component of the polyurethane aqueous liquid is the above-mentioned. It is a carboxyl group-containing polyurethane resin. The non-volatile resin component can be measured by a method known in the technical field of aqueous liquids or aqueous dispersions. For example, when the aqueous liquid or aqueous dispersion is heated and dried at 100 ° C. to 130 ° C. for 1 to 3 hours. The evaporation residue.

  The blending ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) and the carboxyl group-containing polyurethane resin (PU) is EC: PU = 90: 10-40: 60, preferably 80: 20-50: 50. As the blending ratio of the nonvolatile component (EC) of the aqueous ethylene-unsaturated carboxylic acid copolymer dispersion and the nonvolatile component (PU) of the aqueous polyurethane resin liquid, when the EC ratio is greater than 90:10, the tape resistance Peelability deteriorates. On the other hand, when the EC ratio is smaller than 40:60, the alkali degreasing resistance is lowered.

2. Silica Particles The aqueous resin liquid used in the present invention contains silica particles in addition to the nonvolatile resin component of the above-described aqueous dispersion of ethylenic-unsaturated carboxylic acid copolymer and aqueous carboxyl group-containing polyurethane liquid. .
The silica particles impart conductivity, corrosion resistance, and paintability to the resulting resin film, and increase the hardness of the film to improve abrasion resistance.

  In order to maximize the effect of the silica particles, the average particle size of the silica particles is preferably in the range of 4 to 20 nm. The smaller the average particle size of the silica particles, the better the corrosion resistance of the resin film. However, when the average particle size is less than about 4 nm, the effect of improving the corrosion resistance tends to be saturated, and the stability of the aqueous resin liquid decreases. This is because it becomes easy to gel. On the other hand, when the average particle diameter of the silica particles exceeds 20 nm, the film-forming property of the resin film is lowered, and the corrosion resistance, paintability, and alkali degreasing resistance may be lowered.

  As a method for measuring the average particle diameter of the silica particles, it is preferable to employ a Sears method (4 to 6 nm) or a BET method (4 to 20 nm). In the case of chain silica, it is preferable to employ a dynamic light scattering method. Such silica particles are generally known as colloidal silica, and commercially available colloidal silica can be used as the colloidal silica in the present invention.

  Examples of commercially available colloidal silica include “Snowtex (registered trademark)” manufactured by Nissan Chemical Industries, “Adelite (registered trademark)” manufactured by ADEKA, and “Silica Doll (registered trademark)” manufactured by Nippon Chemical Industry Co., Ltd. Etc. As colloidal silica having an average particle size of 4 to 6 nm, for example, “Snowtex (registered trademark) XS” manufactured by Nissan Chemical Industries, Ltd., and as colloidal silica having an average particle size of 10 to 20 nm, manufactured by Nissan Chemical Co., Ltd. It is possible to use “Snowtex (registered trademark) 40”, “Snowtex (registered trademark) N”, “Snowtex (registered trademark) C”, “ADELA (registered trademark) AT-30” manufactured by ADEKA, etc. it can.

  In the resin aqueous liquid used in the present invention, the total amount of the nonvolatile resin component and silica particles of the above-described ethylenic-unsaturated carboxylic acid copolymer aqueous dispersion and carboxyl group-containing polyurethane aqueous liquid is 100 parts by mass. When it does, content of the said silica particle is 55 mass parts or more, Preferably it is 65 mass parts or more, Comprising: It is 80 mass parts or less, Preferably it is 75 mass parts or less. When the content of silica particles is less than 55 parts by mass, the conductivity, abrasion resistance, and tape peel resistance tend to decrease. Moreover, when content of a silica exceeds 80 mass parts, the film forming property of a resin film will fall, and there exists a tendency for corrosion resistance and alkali degreasing resistance to fall.

3. Silane coupling agent The aqueous resin liquid used in the present invention further contains a silane coupling agent. The silane coupling agent is used for enhancing abrasion resistance, paintability, corrosion resistance, and the like, and enhancing adhesion between a metal plate and a resin film formed on the metal plate.

  As the silane coupling agent, a silane coupling agent represented by the following formula (a) is used. By containing the silane coupling agent of the formula (a), the paintability and corrosion resistance of the formed resin film can be improved.

［式（ａ）中、Ｒ¹、Ｒ²はアルコキシ基、Ｒ³はアルコキシ基又は炭素数１〜４のアルキル基、Ｘは炭素数１〜５のアルキレン基を表す。］

[In Formula (a), R ¹ and R ² represent an alkoxy group, R ³ represents an alkoxy group or an alkyl group having 1 to 4 carbon atoms, and X represents an alkylene group having 1 to 5 carbon atoms. ]

The alkoxy group represented by ^{R 1, R 2, R 3} , a methoxy group, an ethoxy group, n- propoxy group, isopropoxy group, n- butoxy group, isobutoxy group, tert- butoxy group, n- pentyloxy group , N-hexyloxy group and the like. Among these, a C1-C4 thing is preferable, More preferably, they are a methoxy group and an ethoxy group. Moreover, since the alcohol produced by hydrolysis of the alkoxy group may cause deterioration of properties when it remains in the film, a methoxy group that produces methanol having a lower boiling point than an ethoxy group produced by ethanol is preferred.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ³ include linear alkyl groups such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group; an isopropyl group, an isobutyl group, and a tert-butyl group. And branched alkyl groups such as cyclopropyl group and cyclobutyl group. Among these, a linear alkyl group is preferable, and a methyl group and an ethyl group are more preferable.
From the viewpoint of solubility in water by hydrolysis of an alkoxy group, as the silane coupling agent, three “trialkoxysilanes” are more preferable than two “dialkoxysilanes”. Accordingly, R ³ is preferably an alkoxy group.

  Examples of the alkylene group represented by X include a methylene group, a dimethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group. Among these, C2-C4 is preferable.

  Examples of the silane coupling agent having a glycidoxy group represented by the chemical formula (a) include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane. , 3-glycidoxypropyltriethoxysilane and the like, and one or more of these can be used in the present invention.

  The silane coupling agent represented by the chemical formula (a) is commercially available, for example, “KBM-402”, “KBM-403”, “KBE-402”, “KBM-402” manufactured by Shin-Etsu Chemical Co., Ltd. And “Z-6040”, “Z-6044”, “Z-6041”, “Z-6042”, “Z-6043” manufactured by Toray Dow Corning.

The content of the silane coupling agent in the resin aqueous liquid is 5 parts by mass or more, preferably 10 parts by mass or more, and 20 parts by mass with respect to 100 parts by mass in total of the nonvolatile resin component and the silica particles described above. Hereinafter, it is preferably 15 parts by mass or less.
If the content of the silane coupling agent is too small, the reactivity between the silica particles and the above-mentioned ethylenic-unsaturated carboxylic acid copolymer, carboxyl group-containing polyurethane resin, etc. is lowered, resulting in abrasion resistance, paintability, and corrosion resistance. Etc. decreases. On the other hand, if the content of the silane coupling agent is too large, the stability of the aqueous resin liquid may decrease and gelation may occur, and the amount of the silane coupling agent that does not contribute to the reaction increases. Adhesion between the plate and the resin film formed on the metal plate may be reduced.

4). Alkoxysilane The aqueous resin liquid used in the present invention further contains alkoxysilane. Alkoxysilane is used to improve the affinity between silica and resin, to form a denser film, and to improve corrosion resistance, alkali degreasing resistance, and the like.

  As the alkoxysilane, an alkoxysilane of the following formula (b) is used.

［式（ｂ）中、Ｒ⁴、Ｒ⁵、Ｒ⁶はアルコキシ基、Ｒ⁷は炭素数５〜７のアルキル基を表す。］

[In the formula (b), R ⁴ , R ⁵ and R ⁶ represent an alkoxy group, and R ⁷ represents an alkyl group having 5 to ⁷ carbon atoms. ]

Examples of the alkoxy group represented by R ⁴ , R ⁵ and R ⁶ include those exemplified for R ¹ , R ² and R ³ . Among these, a C1-C4 thing is preferable, More preferably, they are a methoxy group and an ethoxy group. Moreover, since the alcohol produced by hydrolysis of the alkoxy group may cause deterioration of properties when it remains in the film, a methoxy group that produces methanol having a lower boiling point than an ethoxy group produced by ethanol is preferred.
Examples of the alkyl group having 5 to 7 carbon atoms represented by R ⁷ include linear alkyl groups such as n-pentyl group, n-hexyl group and n-heptyl group; isopentyl group, sec-pentyl, tert-pentyl Group, neopentyl group, isohexyl group, sec-hexyl group, tert-hexyl group, isoheptyl group, sec-heptyl group, tert-heptyl group and other branched alkyl groups; cyclopentyl group, cyclohexyl group, cycloheptyl group and other cyclic alkyl groups Groups and the like. In addition, when the molecular weight of the alkyl group is small, the stability in the treatment liquid deteriorates. On the other hand, when the molecular weight of the alkyl group is large, dissolution in the treatment liquid becomes difficult. Among these, therefore, a linear alkyl group is preferable, and an n-hexyl group is more preferable.

  As described above, the alkoxysilane (b) in the present invention has one specific alkyl group having no functional group, such as pentyltrimethoxysilane, pentyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, Examples include heptyltrimethoxysilane, heptyltriethoxysilane, and the like, and one or more of these can be used in the present invention.

  The alkoxysilane (b) is commercially available, for example, “KBM3033”, “KBM3063”, “KBE3063” manufactured by Shin-Etsu Chemical Co., Ltd., “Z-6582”, “Z-6582” manufactured by Toray Dow Corning, "Z-6586" etc. are mentioned.

The content of the alkoxysilane (b) in the aqueous resin liquid is 1 part by mass or more, preferably 3 parts by mass or more when the total mass part of the nonvolatile resin component and the silica particles is 100 parts by mass. It is 14 parts by mass or less, preferably 12 parts by mass or less.
If the content of alkoxysilane (b) is too small, the affinity between the silica particles and the above-mentioned ethylenic-unsaturated carboxylic acid copolymer, carboxyl group-containing polyurethane resin, etc. will be reduced, resulting in corrosion resistance and alkali degreasing resistance. Etc. decreases. On the other hand, when the content of the alkoxysilane is too large, the stability of the aqueous resin liquid may be reduced and gelation may occur, and adhesion such as paintability and tape peel resistance may be reduced.

5. Other additives The above-described ethylene-unsaturated carboxylic acid copolymer having a carboxyl group neutralized by an amine having a boiling point of 100 ° C. or less and a monovalent metal ion forms an intermolecular association by an ion cluster (ionomerization). ), Forming a resin film having excellent corrosion resistance. However, in order to form a tougher film, it is desirable to crosslink the polymer chains by chemical bonding utilizing a reaction between functional groups. Therefore, the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion used in the present invention preferably contains a crosslinking agent having two or more functional groups capable of reacting with a carboxyl group.

The content ratio of the crosslinking agent is 1 part by mass or more, more preferably 5 parts by mass or more when the nonvolatile resin component (EC) in the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion is 100 parts by mass. And it is desirable to contain it in the ratio of 20 mass parts or less, More preferably, 10 mass parts or less.
If it is 1 part by mass or more, the effect of crosslinking by chemical bonding becomes good, and the effect of improving corrosion resistance is more exhibited. On the other hand, if it is 20 parts by mass or less, the crosslinking density of the resin film becomes excessively high and the hardness is suppressed from increasing, and the deformation at the time of press working can be followed. Therefore, generation | occurrence | production of the crack at the time of press work is suppressed, As a result, corrosion resistance and coating property improve further.

  The crosslinking agent having two or more functional groups capable of reacting with a carboxyl group is not particularly limited, but sorbitol polyglycidyl ether, (poly) glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, trimethylolpropane poly Polyglycidyl ethers such as glycidyl ether, neopentyl glycol diglycidyl ether, (poly) ethylene glycol diglycidyl ether, and glycidyl group-containing crosslinking agents such as polyglycidyl amines; 4,4′-bis (ethyleneiminocarbonylamino) Diphenylmethane, N, N′-hexamethylene-1,6-bis (1-aziridinecarboxamide) N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxyamide), toluenebisua Bifunctional aziridine compounds such as lysine carboxamide; tri-1-aziridinylphosphine oxide, tris [1- (2-methyl) aziridinyl] phosphine oxide, trimethylolpropane tris (β-aziridinylpropionate), tris An aziridinyl group-containing crosslinking agent such as a tri- or higher functional aziridine compound such as 2,4,6- (1-aziridinyl) -1,3,5-triazine, tetramethylpropanetetraaziridinylpropionate, or a derivative thereof. Are mentioned as preferred examples, and one or more of them can be used. Of these, aziridinyl group-containing crosslinking agents are preferred. In addition, you may use together polyfunctional aziridine and monofunctional aziridine (ethyleneimine etc.).

  The surface treatment composition of the present invention may further contain spherical polyolefin wax particles (preferably spherical polyethylene wax particles). By containing spherical polyolefin wax particles, the lubricity of the resin-coated metal plate is improved, and the contact resistance between the metal plate and the mold can be reduced during processing such as press molding.

  The average particle diameter of the spherical polyolefin wax particles for efficiently exhibiting lubricity is preferably 0.6 μm or more, more preferably 1 μm or more. However, if the average particle diameter becomes too large, the coating film adhesion may be deteriorated. Therefore, the average particle diameter of the spherical polyolefin wax particles is preferably 4 μm or less, more preferably 3 μm or less. The average particle diameter of the spherical polyolefin wax particles can be measured by a Coulter counter method.

  As the spherical polyolefin wax particles, for example, “Chemical (registered trademark)” series (polyolefin aqueous dispersion) manufactured by Mitsui Chemicals, Inc., more specifically, Chemipearl W-100, W-300, W-400, W-500, W-700, W-900, etc. are mentioned.

  The amount of the spherical polyolefin wax particles is preferably 0.5 parts by mass or more, based on 100 parts by mass of the total mass of the nonvolatile resin component and silica particles described above, from the viewpoint of lubricity and coating film adhesion. Preferably it is 1.0 mass part or more, Preferably it is 5 mass parts or less, More preferably, it is 4 mass parts or less.

  Further, the surface treatment composition is a diluent, anti-skinning agent, surfactant, emulsifier, dispersant, leveling agent, antifoaming agent, penetrating agent, film-forming aid, and dye as long as the effects of the present invention are not impaired. , Pigments, thickeners, rust inhibitors and the like can also be contained.

6). Preparation Method of Resin Aqueous Liquid The preparation method of the resin aqueous liquid is not particularly limited, but the ethylenic-unsaturated carboxylic acid copolymer aqueous dispersion, carboxyl group-containing polyurethane aqueous liquid, silica particles, silane It can be obtained by blending a predetermined amount of a coupling agent (a), an alkoxysilane (b), and, if necessary, a wax, a crosslinking agent and the like. Silica particles, silane coupling agent (a), alkoxysilane (b), wax, and crosslinking agent may be added at any stage, but crosslinking is performed after the addition of the crosslinking agent and silane coupling agent (a). It is desirable not to apply heat so that the reaction does not progress and gel. Furthermore, it is desirable that heat is not applied during storage of the aqueous liquid due to the above circumstances, and it is desirable to store at 30 ° C. or lower, preferably 20 ° C. or lower.

  In preparing the treatment liquid, a small amount of an organic solvent may be blended in order to reduce the interfacial tension and improve the wettability to the metal plate. Examples of the organic solvent for this purpose include methanol, ethanol, isopropanol, butanol, hexanol, 2-ethylhexanol, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol, and propylene glycol.

7). Metal plate Although the metal plate used by this invention is not specifically limited, such as a steel plate, an aluminum plate, and a Ti plate, it is preferable that it is a galvanized steel plate. For example, hot-dip galvanized steel sheet, alloyed hot-dip galvanized steel sheet, hot-dip Zn-5% Al-plated steel sheet, hot-dip Zn-55% Al-plated steel sheet, electric pure galvanized steel sheet, electric Zn-Ni-plated steel sheet can do. Further, before forming the resin film, the surface of the metal plate may be subjected to a treatment such as Co or Ni, an inhibitor treatment, or various non-chromate ground treatments.

8). Forming method of resin film In order to form a resin film on a metal plate, the resin aqueous liquid is applied to the surface of the metal plate using a known coating method, that is, a roll coater method, a spray method, a curtain flow coater method, or the like. What is necessary is just to apply | coat to one side or both surfaces, and to heat-dry. The heating and drying temperature is preferably performed at a temperature at which water in the aqueous liquid is sufficiently evaporated. In addition, when spherical polyethylene wax is used as the lubricant, it is preferable to perform drying in the range of 70 to 130 ° C. because maintaining the spherical shape improves the workability in the subsequent processing step. .

Amount of adhesion to the metal plate of resin film (thickness), after drying, 0.05 g / m ² or more, more preferably be at 0.2 g / m ² or more, 1 g / m ² or less, more preferably 0 It is desirable that it is not more than 5 g / m ² . When the adhesion amount is too small, abrasion resistance, corrosion resistance, and alkali degreasing resistance decrease. On the other hand, when the amount of adhesion is too large, the conductivity and paintability tend to decrease. This surface-treated metal plate can be used as it is after being processed according to the application, or it can be used after electrodeposition coating, powder coating, silk printing (about 130 to 160 ° C, about 20 to 30 minutes) under conventional conditions. May be.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.

[Evaluation method]
1. Corrosion resistance The obtained surface-treated metal plate (resin-coated steel plate) was subjected to a salt spray test of an edge-sealed flat plate according to JIS Z2371, and evaluated by the time until white rust was generated by 5%.
Evaluation criteria ◎: White rust occurrence 240 hours or more ○: White rust occurrence 120 hours to less than 240 hours △: White rust occurrence 72 hours to less than 120 hours ×: White rust occurrence less than 72 hours

2. Alkali degreasing resistance The test material was immersed for 2 minutes in 20 g / l of an alkaline degreasing agent (Nippon Parker Rising Co., Ltd., “L-4460”) adjusted to a liquid temperature of 60 ° C., pulled up, washed with water, and dried. The specimen was subjected to a salt spray test in accordance with JIS Z2371, and evaluated by the time until 1% of white rust was generated.
Evaluation criteria ◎: 168 hours or more ○: 96 hours or more and less than 168 hours Δ: 48 hours or more and less than 96 hours ×: less than 48 hours

3. Conductivity Measure the surface resistance of the obtained surface-treated metal plate (resin-coated steel plate) with a surface resistance meter (Dia Instruments, “Loresta (registered trademark) -EP”, 4-terminal 4-probe method) at 10 locations. did.
Evaluation criteria ◎: Overload 0 times / 10 places at 1 mΩ or less ○ Overload 1 time / 10 places at 1 mΩ or less △: Overload 2 to 4 times / 10 places at 1 mΩ or less / 10 places x: Overload 5 at 1 mΩ or more More than 10 times

4). Paintability To the obtained surface-treated metal plate (resin-coated steel plate), a melamine alkyd paint (“Amirac (registered trademark) # 1000” manufactured by Kansai Paint Co., Ltd.) is applied so that the coating thickness after drying is about 20 μm. Then, spray coating was carried out, and baking was performed at 130 ° C. for 20 minutes, followed by coating. Subsequently, after immersing this test material in boiling water for 1 hour, taking it out and allowing it to stand for 1 hour, 100 mm of 1 mm square grids were cut with a cutter knife, and a tape peeling test was performed on this to leave the coating film remaining. The coating film adhesion was evaluated in four stages according to the number of cells.
Evaluation criteria ◎: Residual rate: 100%
○: Residual rate: 90% to less than 100% Δ: Residual rate: 80% to less than 90% ×: Residual rate: 70% to less than 80%

5. Ablation resistance The obtained surface-treated metal sheet (resin-coated steel sheet) was subjected to a vibration test in accordance with the packaging cargo-vibration test (JIS Z0232), and the appearance of the specimen after a predetermined time was determined according to the following standards. Based on the evaluation. In addition, the brand name "BF-500UC" by IDEC company was used for the vibration test apparatus.
Evaluation standard ◎: No damage to the film ○: Damage to the film, but no damage to the galvanized surface △: Damage to the galvanized surface that can be visually confirmed ×: Damage to the galvanized surface Remarkable

6). Tape peeling resistance Filament tape (Maxell Sliontec Co., Ltd., “Filament Tape # 9510”) is pasted on the surface of the test material, stored in an atmosphere of 40 ° C. × RH 98% for 120 hours, and then the filament tape is peeled off to form a film. The ratio of the remaining area (remaining rate) was measured.
Evaluation standard ◎: Residual rate 100%
○: Residual rate 90% or more and less than 100% Δ: Residual rate 80% or more and less than 90% ×: Residual rate less than 80

Preparation of Ethylene-Unsaturated Carboxylic Acid Copolymer Aqueous Dispersion Into an autoclave of an emulsification facility with an internal capacity of 0.8 L equipped with a stirrer, thermometer and temperature controller, (Acrylic acid 20% by mass, melt index (MI) 300 g / 10 min (190 ° C., 2.16 kg)) 160 parts by mass were added, and triethylamine was added in an amount of 0.001 to 1 mol of the carboxyl group of the ethylene-acrylic acid copolymer. 4 mol (40 mol%) and 0.15 mol (15 mol%) of sodium hydroxide were added. The mixture was stirred at high speed under an atmosphere of 150 ° C. and 5 Pa, and cooled to 40 ° C. to obtain an aqueous dispersion of an ethylene-acrylic acid copolymer. Subsequently, 4,4′-bis (ethyleneiminocarbonylamino) diphenylmethane (manufactured by Nippon Shokubai Co., Ltd., “Chemite (registered trademark) DZ-22E”) was added to the aqueous dispersion as a crosslinking agent. It added so that it might become a ratio of 5 mass parts with respect to 100 mass parts of united non-volatile resin components.

Preparation of aqueous solution of carboxyl group-containing polyurethane resin Polytetramethylene ether glycol (manufactured by Hodogaya Chemical Co., Ltd., number average molecular weight 1000) as a polyol component in a 0.8 L internal synthesizer equipped with a stirrer, thermometer and temperature controller 60 g, 14 g of 1,4-cyclohexanedimethanol and 20 g of dimethylolpropionic acid were added, and 30.0 g of N-methylpyrrolidone was further added as a reaction solvent. 104 g of tolylene diisocyanate was added as an isocyanate component, and the temperature was raised from 80 to 85 ° C. and reacted for 5 hours. The obtained prepolymer had an NCO content of 8.9% by mass. Further, 16 g of triethylamine was added for neutralization, a mixed aqueous solution of 16 g of ethylenediamine and 480 g of water was added, emulsified at 50 ° C. for 4 hours, and subjected to chain extension reaction to obtain an aqueous polyurethane resin dispersion (nonvolatile resin component 29 0.1%, acid value 41.4 mg KOH / g).

Example 1 of preparation of aqueous resin liquid and preparation of surface-treated metal plate
Carboxyl group-containing polyurethane resin aqueous solution obtained above, ethylene-acrylic acid copolymer aqueous dispersion, silica particles (manufactured by Nissan Chemical Co., Ltd., “Snowtex (registered trademark) XS”, average particle diameter (BET method) 4 to 6 nm) is blended in a total of 100 parts by mass in terms of nonvolatile components so as to have the blending ratio shown in Table 1, and γ-glycidoxypropyltrimethoxy is further added as a silane coupling agent to the total 100 parts by mass. 12 parts by mass of silane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM-403”) and 6 parts by mass of hexyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM-3063”) as an alkoxysilane are added, and an aqueous resin liquid is added. Prepared.
This aqueous resin solution was applied to the surface of an electropure galvanized steel sheet with a drawing roll and dried by heating at a plate temperature of 90 ° C. to form a surface-treated metal plate on which a resin film having an adhesion amount of 0.5 g / m ² was formed ( A resin-coated steel sheet was obtained. Table 1 shows the results of evaluating the corrosion resistance, conductivity, abrasion resistance, alkali degreasing resistance, paintability, etc. of the obtained resin-coated steel sheet.
In addition, as the said electropure galvanized steel plate, the electrogalvanized steel plate which does not perform a chromate process (Zn adhesion amount 20g / m < ² >, plate thickness 0.8mm) was used.

Steel plate No. 4 to 9 and 14 to 18 contain the resin aqueous liquid so that the nonvolatile resin component 20 to 45 parts by mass and the silica particles 55 to 80 parts by mass are 100 parts by mass in total, and the nonvolatile resin As a component, the non-volatile resin component (EC) of the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion and the non-volatile resin component (PU) of the carboxyl group-containing polyurethane resin aqueous liquid are contained. The mass ratio is EC: PU = 90: 10 to 40:60. It can be seen that these steel plates are excellent in corrosion resistance, alkali degreasing resistance, conductivity, paintability, abrasion resistance, and tape peel resistance.
Steel plate No. 1-3 is a case where the ratio of a non-volatile resin component is less than 20 mass parts, and corrosion resistance and alkali degreasing resistance fell.
Steel plate No. 10 and 11 are cases where the ratio of the nonvolatile resin component exceeds 45 parts by mass, and the conductivity, abrasion resistance, and tape peel resistance were lowered.
Steel plate No. Nos. 12 and 13 are cases where the EC ratio in the nonvolatile resin component was too high, and the tape peel resistance was lowered.
Steel plate No. 19 and 20 are cases where the ratio of PU in the nonvolatile resin component is too high, and the alkali degreasing resistance was lowered.

Experimental example 2
The carboxyl group-containing polyurethane resin aqueous solution obtained above, the ethylene-acrylic acid copolymer aqueous dispersion, and the silica particles are 30 parts by mass of the nonvolatile resin component and 70 parts by mass of the silica particles, for a total of 100 parts by mass. 0 to 30 masses of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM-403”) as a silane coupling agent with respect to 100 mass parts in total. 6 parts by mass of hexyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM-3063”) was added as an alkoxysilane to prepare an aqueous resin liquid. As silica particles, “Snowtex XS (average particle diameter (BET method) 4 to 6 nm)” manufactured by Nissan Chemical Industries, Ltd. is used, and an ethylene-unsaturated carboxylic acid copolymer (EC) in a nonvolatile resin component. And the carboxyl group-containing polyurethane resin (PU) were in a mass ratio of EC: PU = 70: 30.
This aqueous resin solution was applied to the surface of an electropure galvanized steel sheet with a drawing roll and dried by heating at a plate temperature of 90 ° C. to form a surface-treated metal plate on which a resin film having an adhesion amount of 0.5 g / m ² was formed ( A resin-coated steel sheet was obtained. The obtained resin-coated steel sheet was evaluated for the resin film composition, corrosion resistance, electrical conductivity, abrasion resistance, alkali degreasing resistance, paintability, and the like, as shown in Table 2.
In addition, as the said electropure galvanized steel plate, the electrogalvanized steel plate which does not perform a chromate process (Zn adhesion amount 20g / m < ² >, plate thickness 0.8mm) was used.

Steel plate No. 6 and 22 to 25, the resin aqueous liquid has a silane coupling agent (a) of 5 to 20 parts by mass and an alkoxysilane (b) of 6 parts by mass with respect to a total of 100 parts by mass of the nonvolatile resin component and the silica particles. Although it is a case where it contains by the ratio of a part, it turns out that any steel plate is excellent in corrosion resistance, alkali degreasing resistance, electroconductivity, coating property, abrasion resistance, and tape peeling resistance.
On the other hand, steel plate No. containing no silane coupling agent (a). In No. 21, corrosion resistance, alkali degreasing resistance, paintability, abrasion resistance, and tape peel resistance were lowered.
In addition, the amount of the silane coupling agent (a) added is too large. In 26 and 27, paintability, abrasion resistance, and tape peel resistance were lowered.

Experimental example 3
The carboxyl group-containing polyurethane resin aqueous solution obtained above, the ethylene-acrylic acid copolymer aqueous dispersion, and the silica particles are 30 parts by mass of the nonvolatile resin component and 70 parts by mass of the silica particles, for a total of 100 parts by mass. 12 parts by mass of γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM-403”) as a silane coupling agent with respect to 100 parts by mass in total. 0-20 parts by mass of hexyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM-3063”) was added as an alkoxysilane to prepare an aqueous resin liquid. As silica particles, “Snowtex XS (average particle diameter (BET method) 4 to 6 nm)” manufactured by Nissan Chemical Industries, Ltd. is used, and an ethylene-unsaturated carboxylic acid copolymer (EC) in a nonvolatile resin component (EC). ) And the carboxyl group-containing polyurethane resin (PU) in terms of mass ratio, EC: PU = 70: 30.
This aqueous resin solution was applied to the surface of an electropure galvanized steel sheet with a drawing roll and dried by heating at a plate temperature of 90 ° C. to form a surface-treated metal plate on which a resin film having an adhesion amount of 0.5 g / m ² was formed ( A resin-coated steel sheet was obtained. The obtained resin-coated steel sheet was evaluated for the resin film composition, corrosion resistance, electrical conductivity, abrasion resistance, alkali degreasing resistance, paintability and the like as shown in Table 3.
In addition, as the said electropure galvanized steel plate, the electrogalvanized steel plate which does not perform a chromate process (Zn adhesion amount 20g / m < ² >, plate thickness 0.8mm) was used.

Steel plate No. 6 and 29 to 33, the resin aqueous liquid is 12 parts by mass of the silane coupling agent (a) and 1 to 14 parts by mass of the alkoxysilane (b) with respect to 100 parts by mass in total of the nonvolatile resin component and the silica particles. Although it is a case where it contains by the ratio of a part, it turns out that any steel plate is excellent in corrosion resistance, alkali degreasing resistance, electroconductivity, coating property, abrasion resistance, and tape peeling resistance.
On the other hand, steel plate No. containing no alkoxysilane (b). In 28, corrosion resistance and alkali degreasing resistance were lowered.
Moreover, the steel plate No. 2 in which the amount of alkoxysilane (b) added is too large. In 34 and 35, corrosion resistance, alkali degreasing resistance, paintability, abrasion resistance, and tape peel resistance decreased.

Experimental Example 4
The polyurethane resin aqueous solution obtained above, the ethylene-acrylic acid copolymer aqueous dispersion, and silica particles having an average particle size of 4 to 100 nm (Nissan Chemical Co., Ltd., “Snowtex” series) are combined with a nonvolatile resin component. 30 parts by mass and silica particles 70 parts by mass in total 100 parts by mass, and γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent with respect to the total 100 parts by mass , “KBM-403”) and 12 parts by mass of hexyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM-3063”) as an alkoxysilane were added to prepare an aqueous resin solution. In addition, the compounding ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) and the carboxyl group-containing polyurethane resin (PU) in the nonvolatile resin component was mass ratio, and EC: PU = 70: 30.
This aqueous resin solution was applied to the surface of an electropure galvanized steel sheet with a drawing roll and dried by heating at a plate temperature of 90 ° C. to form a surface-treated metal plate on which a resin film having an adhesion amount of 0.5 g / m ² was formed ( A resin-coated steel sheet was obtained. The obtained resin-coated steel sheet was evaluated for the resin film composition, corrosion resistance, conductivity, abrasion resistance, alkali degreasing resistance, paintability, and the like.
In addition, as the said electropure galvanized steel plate, the electrogalvanized steel plate which does not perform a chromate process (Zn adhesion amount 20g / m < ² >, plate thickness 0.8mm) was used.

Steel plate No. 36 and 37 are cases where the average particle diameter of the silica particles is 4 to 6 nm or 10 to 20 nm, and all the steel plates have corrosion resistance, alkali degreasing resistance, conductivity, paintability, abrasion resistance, and tape peeling resistance. It turns out that it is excellent in property.
On the other hand, steel plate No. whose average particle diameter of a silica particle is 40-60 nm or 70-100 nm. In Nos. 38 and 39, the alkali degreasing resistance, conductivity, paintability, abrasion resistance, and tape peel resistance were lowered.

Experimental Example 5
The polyurethane resin aqueous liquid obtained above, the ethylene-acrylic acid copolymer aqueous dispersion, silica particles (manufactured by Nissan Chemical Co., Ltd., “Snowtex XS”, average particle diameter (BET method) 4 to 6 nm), 30 parts by mass of the non-volatile resin component and 70 parts by mass of silica particles are blended in a total of 100 parts by mass. To this total of 100 parts by mass, 12 parts by mass of the silane coupling agent shown in Table 5 and hexyl as alkoxysilane An aqueous resin liquid was prepared by adding 6 parts by mass of trimethoxysilane (“KBM-3063” manufactured by Shin-Etsu Chemical Co., Ltd.). In addition, the compounding ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) and the carboxyl group-containing polyurethane resin (PU) in the nonvolatile resin component was mass ratio, and EC: PU = 70: 30.
This aqueous resin solution was applied to the surface of an electropure galvanized steel sheet with a drawing roll and dried by heating at a plate temperature of 90 ° C. to form a surface-treated metal plate on which a resin film having an adhesion amount of 0.5 g / m ² was formed ( A resin-coated steel sheet was obtained. The obtained resin-coated steel sheet was evaluated for the resin film composition, corrosion resistance, conductivity, abrasion resistance, alkali degreasing resistance, paintability, and the like, as shown in Table 5.
In addition, as the said electropure galvanized steel plate, the electrogalvanized steel plate which does not perform a chromate process (Zn adhesion amount 20g / m < ² >, plate thickness 0.8mm) was used.

  As shown in Table 5, the steel plate No. using a compound other than the silane coupling agent represented by the formula (a). In 42 to 44, the stability of the aqueous resin liquid was poor, and a resin film could not be formed.

Experimental Example 6
The polyurethane resin aqueous liquid obtained above, the ethylene-acrylic acid copolymer aqueous dispersion, silica particles (manufactured by Nissan Chemical Co., Ltd., “Snowtex XS”, average particle diameter (BET method) 4 to 6 nm), 100 parts by mass in total of 30 parts by mass of the nonvolatile resin component and 70 parts by mass of silica particles are blended, and γ-glycidoxypropyltrimethoxysilane (Shin-Etsu) as a silane coupling agent with respect to the total 100 parts by mass. An aqueous resin liquid was prepared by adding 12 parts by mass of “KBM-403” manufactured by Chemical Industry Co., Ltd. and 6 parts by mass of alkoxysilane shown in Table 6. In addition, the compounding ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) and the carboxyl group-containing polyurethane resin (PU) in the nonvolatile resin component was mass ratio, and EC: PU = 70: 30.
This aqueous resin solution was applied to the surface of an electropure galvanized steel sheet with a drawing roll and dried by heating at a plate temperature of 90 ° C. to form a surface-treated metal plate on which a resin film having an adhesion amount of 0.5 g / m ² was formed ( A resin-coated steel sheet was obtained. The resulting resin-coated steel sheet was evaluated for the resin film composition, corrosion resistance, electrical conductivity, abrasion resistance, alkali degreasing resistance, paintability, etc., as shown in Table 6.
In addition, as the said electropure galvanized steel plate, the electrogalvanized steel plate which does not perform a chromate process (Zn adhesion amount 20g / m < ² >, plate thickness 0.8mm) was used.

  As shown in Table 6, steel plate No. 1 using an alkoxysilane having an alkyl group with 1 or 2 carbon atoms. In Nos. 45 and 46, the stability of the aqueous resin liquid was poor and a resin film could not be formed. Steel plate No. 1 using alkoxysilane having 3 or 4 carbon atoms in the alkyl group. In 47 and 48, the tape peel resistance was poor. On the other hand, steel plate No. 1 using an alkoxysilane having an alkyl group with 8 or 10 carbon atoms. In Nos. 50 and 51, the solubility of alkoxysilane in the aqueous resin solution was poor, and an aqueous resin solution could not be prepared.

Experimental Example 7
The polyurethane resin aqueous liquid obtained above, the ethylene-acrylic acid copolymer aqueous dispersion, silica particles (manufactured by Nissan Chemical Co., Ltd., “Snowtex XS”, average particle diameter (BET method) 4 to 6 nm), 100 parts by mass in total of 30 parts by mass of the nonvolatile resin component and 70 parts by mass of silica particles are blended, and γ-glycidoxypropyltrimethoxysilane (Shin-Etsu) as a silane coupling agent with respect to the total 100 parts by mass. A chemical aqueous solution was prepared by adding 12 parts by mass of “KBM-403” manufactured by Chemical Industry Co., Ltd. and 6 parts by mass of hexyltrimethoxysilane (“KBM-3063” manufactured by Shin-Etsu Chemical Co., Ltd.) as an alkoxysilane. In addition, the compounding ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) and the carboxyl group-containing polyurethane resin (PU) in the nonvolatile resin component was mass ratio, and EC: PU = 70: 30.
This resin aqueous liquid is applied to the surface of an electropure galvanized steel sheet with a squeeze roll, dried by heating at a plate temperature of 90 ° C., and by changing the squeeze pressure of the roll, the adhesion amount 0.05 to 2.0 g / m A surface-treated metal plate (resin-coated steel plate) on which a resin film ² was formed was obtained. The resulting resin-coated steel sheet was evaluated for the resin film composition, corrosion resistance, electrical conductivity, abrasion resistance, alkali degreasing resistance, paintability, etc., as shown in Table 7.
In addition, as the said electropure galvanized steel plate, the electrogalvanized steel plate which does not perform a chromate process (Zn adhesion amount 20g / m < ² >, plate thickness 0.8mm) was used.

As shown in Table 7, if the adhesion amount of the resin film on the metal plate is in the range of 0.05 to 1 g / m ² , corrosion resistance, alkali degreasing resistance, conductivity, paintability, abrasion resistance, tape resistance A surface-treated metal plate excellent in peelability was obtained.

  The surface-treated metal sheet of the present invention is excellent in corrosion resistance, alkali degreasing resistance, conductivity, paintability (coating film adhesion), abrasion resistance, and tape peel resistance, and is therefore suitable for automobiles, home appliances, building materials, etc. Can be used.

Claims (3)

A surface-treated metal plate comprising a metal plate and a resin film obtained from an aqueous resin liquid formed on at least one side of the metal plate,
The resin aqueous liquid contains 20 to 45 parts by mass of a nonvolatile resin component and 55 to 80 parts by mass of silica particles having an average particle diameter of 4 to 20 nm so that the total amount becomes 100 parts by mass,
As the non-volatile resin component, a non-volatile resin component (EC) of an ethylene-unsaturated carboxylic acid copolymer aqueous dispersion and a non-volatile resin component (PU) of a carboxyl group-containing polyurethane resin aqueous liquid are contained, and these The blending ratio is EC: PU = 90: 10-40: 60 by mass ratio,
Furthermore, 5 to 20 parts by mass of the silane coupling agent represented by the formula (a) and the alkoxysilane represented by the formula (b) with respect to 100 parts by mass in total of the nonvolatile resin component and the silica particles. 1-14 mass parts is contained, The surface treatment metal plate characterized by the above-mentioned.

[In Formula (a), R ¹ and R ² represent an alkoxy group, R ³ represents an alkoxy group or an alkyl group having 1 to 4 carbon atoms, and X represents an alkylene group having 1 to 5 carbon atoms. ]

[In the formula (b), R ⁴ , R ⁵ and R ⁶ represent an alkoxy group, and R ⁷ represents an alkyl group having 5 to ⁷ carbon atoms. ]   The surface-treated metal sheet according to claim 1, wherein the alkoxysilane represented by the formula (b) is hexyltrimethoxysilane. The adhered amount of the resin coating, a surface treated metal sheet according to claim 1 or 2 which is 0.05 to 1 g / m ^2.