KR101452051B1 - Surface-treated metal sheet having excellent corrosion resistance and conductivity - Google Patents

Abstract

The surface-treated metal sheet of the present invention comprises a metal sheet and a resin coating obtained from an aqueous resin solution formed on at least one side of the metal sheet, wherein the resin aqueous solution contains a nonvolatile resin component and silica particles, (EC) of an aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer and a nonvolatile resin component (PU) of an aqueous solution of a carboxyl group-containing polyurethane resin in a mass ratio of EC: PU = 90:10 to 40:60 And 5 to 20 parts by mass of a silane coupling agent and 1 to 14 parts by mass of an alkoxysilane based on 100 parts by mass of the total of the nonvolatile resin component and the silica particles. The surface-treated metal sheet of the present invention further improves the corrosion resistance, the alkali-alkali rust resistance, the conductivity, the paintability, the outbreak resistance and the tape peelability.

Description

TECHNICAL FIELD [0001] The present invention relates to a surface-treated metal sheet having excellent corrosion resistance and conductivity,

TECHNICAL FIELD The present invention relates to a surface-treated metal plate, and more particularly to a surface-treated metal plate which is excellent in corrosion resistance, alkali-alkali degreasing property, conductivity, paintability (coating film adhesion) To a surface-treated metal plate.

As materials used for automobiles, household appliances, building materials, etc., zinc plated steel sheets and hot-dip galvanized steel sheets, zinc-plated steel sheets, chromate- Steel plates subjected to treatment or zinc phosphate treatment have been widely used. There has also been proposed a resin-coated steel sheet in which an organic resin film is formed on a surface-treated steel sheet subjected to a chromate treatment for the purpose of further improving corrosion resistance, paintability and workability.

In recent years, in view of global environmental preservation, there has been an increase in demand for steel sheets which have not undergone chromate treatment, and various steel sheets having an organic resin film formed without containing hexavalent chromium have been proposed. However, since it is very difficult to secure corrosion resistance without performing a chromate treatment, it is very difficult to secure sufficient corrosion resistance with a thin film.

On the other hand, there is an increasing demand for a material having excellent conductivity to cope with antistatic property and electromagnetic shielding property of a steel sheet to be used in accordance with high performance of electric devices. Regarding the conductivity, when the coating is applied on the galvanized steel sheet, it is necessary to secure the conductivity by lowering the coating amount of the coating. However, in a product in which an organic resin film is provided on a galvanized steel sheet, if the adhesion amount of the organic resin film is low, the corrosion resistance and workability are deteriorated, so that characteristics other than conductivity become insufficient and are not suitable for practical use.

In order to solve the above-described problems of the resin-coated steel sheet, there has been proposed a lubricating steel sheet having a coating film containing an inorganic polymer compound and a solid lubricant as a resin coating, and a lubricating steel sheet having a coating film further comprising a water-based resin. However, in view of global environment preservation, cleaning by alkaline degreasing has been increasing in place of organic solvent-based degreasing agents such as trichlorethylene and methylene chloride which have been conventionally used in a cleaning process after press processing. In these products, The intellect is inadequate and is not suitable for practical use. Further, for example, Japanese Patent Application Laid-Open No. 2006-43913 (Patent Document 1) also discloses a resin coating containing silica and a silane coupling agent in a resin aqueous solution.

Japanese Patent Application Laid-Open No. 2006-43913

However, in the surface-treated metal sheet described in the patent publication, the polyurethane resin content in the nonvolatile resin component constituting the resin coating is increased to 67 to 90 mass%. Therefore, it can not be said that it has a sufficient alkali alkali degreasing property in a use condition in which the alkali degreasing conditions are strict, and a surface-treated metal plate having more excellent alkali-resistant property is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surface-treated metal plate which is further improved in corrosion resistance, alkali resistance, conductivity, paintability, outbreak resistance and tape peelability.

A surface-treated metal sheet according to the present invention capable of solving the above-mentioned problems is a surface-treated metal sheet comprising a metal sheet and a resinous coating obtained from an aqueous resinous solution formed on at least one side of the metal sheet. The resinous aqueous solution contains a non- And 45 to 80 parts by mass of silica particles having an average particle diameter of 4 to 20 nm are added in a total amount of 100 parts by mass, and the nonvolatile resin component (EC And a nonvolatile resin component (PU) of an aqueous solution of a carboxyl group-containing polyurethane resin, wherein the compounding ratio is EC: PU = 90: 10 to 40: 60 in a mass ratio, 5 to 20 parts by mass of the silane coupling agent represented by the formula (a) and 1 to 14 parts by mass of the alkoxysilane represented by the formula (b) are added to 100 parts by mass of the total of the particles Oil, and adhesion amount of the resin film is 0.05~1g / m ^2.

(A)

Wherein R ¹ and R ² are an alkoxy group, R ³ is an alkoxy group or an alkyl group having 1 to 4 carbon atoms, and X is an alkylene group having 1 to 5 carbon atoms.

[Formula b]

Wherein R ⁴ , R ⁵ and R ⁶ are an alkoxy group and R ⁷ is an alkyl group having 5 to ⁷ carbon atoms.

The surface-treated metal sheet of the present invention is characterized in that the resin coating contains an ethylene-unsaturated carboxylic acid copolymer as a resin component and a carboxyl group-containing polyurethane resin and a specific amount of silica particles and also a specific silane coupling agent and a specific alkoxysilane And the like. In particular, the content of the ethylene-unsaturated carboxylic acid copolymer in the resin component is high. Therefore, the surface-treated metal sheet of the present invention is excellent in corrosion resistance, conductivity, paintability, out-of-braking resistance and inner tape peelability, and also superior in alkali degreasing ability.

The surface-treated metal sheet of the present invention comprises a metal sheet and a resin coating obtained from an aqueous resin solution formed on at least one side of the metal sheet.

The resin aqueous liquid used in the present invention 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 as to be 100 parts by mass in total. Here, the nonvolatile resin component includes a nonvolatile resin component (EC) of an aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer and a nonvolatile resin component (PU) of a carboxyl group-containing polyurethane resin aqueous solution, The ratio of EC: PU = 90: 10 to 40: 60 is adjusted by this mass ratio. The resin aqueous liquid is prepared by mixing 5 to 20 parts by mass of a silane coupling agent (hereinafter referred to as " silane coupling agent (a) ") represented by the general formula a with respect to 100 parts by mass of a total of 100 parts by mass of the non- And 1 to 14 parts by mass of alkoxysilane (hereinafter referred to as " alkoxysilane (b) ") represented by the general formula (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 the alkoxysilane (b) for improving the affinity between the nonvolatile resin and the silica particles Treated metal sheet which is excellent in corrosion resistance, conductivity, paintability, out-to-break and adhesive tape peelability and also has excellent alkali-proofing ability can be obtained by forming a resin coating film using a resin aqueous solution having a high content Loses.

Hereinafter, the present invention will be described in detail.

1. Non-volatile resin component

The resin aqueous 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 the ethylene-unsaturated carboxylic acid copolymer and the carboxyl group-containing polyurethane resin in combination, a surface-treated metal sheet excellent in paintability, corrosion resistance, resistance to braking and alkali resistance to degreasing can be obtained. The ethylene-unsaturated carboxylic acid copolymer and the carboxyl group-containing polyurethane resin are each compounded in an aqueous resin solution as an aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer and a carboxyl group-containing polyurethane resin aqueous solution.

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 the ethylene-unsaturated carboxylic acid copolymer is dispersed in an aqueous medium. The aqueous medium may contain, in addition to water, a small amount of a hydrophilic solvent such as alcohol, N-methylpyrrolidone, or acetone.

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, etc., and by polymerizing at least one of these with ethylene by a known high- The merger can be obtained. As the copolymer, random is most preferable, but a block copolymer or a copolymer grafted with an unsaturated carboxylic acid moiety may be used. On the other hand, as the unsaturated carboxylic acid, (meth) acrylic acid is suitable. Further, instead of a part of ethylene, an olefin-based monomer such as propylene or 1-butene may be used. In this case, the content of the olefin-based monomer other than ethylene is preferably 10% by mass or less. In addition, as long as the object of the present invention is not impaired, other known vinyl monomers may be partially copolymerized (about 10% by mass or less).

It is preferable that the ethylene-unsaturated carboxylic acid copolymer has 10 to 40 mass% of the unsaturated carboxylic acid component copolymerized with 100 mass% of the total monomer. When the content of the unsaturated carboxylic acid is 10% by mass or more, the starting point of the intermolecular association by the ion clusters or the number of carboxyl groups which become a crosslinking point with the crosslinking agent becomes large. As a result, the film strength effect is improved and the corrosion resistance after the degreasing process is improved, and the emulsion stability of the aqueous dispersion is also improved. The lower limit of the more preferable unsaturated carboxylic acid is 15 mass%. On the other hand, when the content of the unsaturated carboxylic acid is 40 mass% or less, the corrosion resistance and water resistance of the resin film are further improved, and the corrosion resistance after the alkali degreasing step is further improved. A more preferable upper limit is 25 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 a metal ion.

It is preferable to use an amine having a boiling point of 100 캜 or less as the organic base. Amines having a boiling point exceeding 100 占 폚 are liable to remain in the resin film on the metal plate when the resin aqueous solution is dried, thereby increasing the water absorption of the resin film, thereby causing deterioration in corrosion resistance. Therefore, it is preferable that the aqueous dispersion of the ethylene-unsaturated carboxylic acid copolymer used in the present invention does not contain an amine having a boiling point of higher than 100 캜. Further, since the effect of addition of ammonia has not been confirmed, it is preferable that ammonia is not included. The boiling point adopts the boiling point at atmospheric pressure.

Specific examples of the amine having a boiling point of 100 DEG C or lower include triethylamine, N, N-dimethylbutylamine, N, N-dimethylallylamine, N-methylpyridine, tetramethyldiaminomethane, Tertiary amines; Secondary amines such as N-methylethylamine, diisopropylamine and diethylamine; There may be mentioned primary amines such as propylamine, t-butylamine, sec-butylamine, isobutylamine, 1,2-dibutylpropylamine and 3-pentylamine, Can be used. Of these, tertiary amines are preferred, and triethylamine is most preferred.

The amount of the amine having a boiling point of 100 DEG C or lower is preferably in the range of 0.2 to 0.8 mol (20 to 80 mol%) relative to 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. This range is because the corrosion resistance is good. When the amount of the amine having a boiling point of 100 DEG C or lower is 0.2 mol or more, the particle size of the resin particle of the aqueous dispersion is reduced and the above effect is considered to be improved. When it is 0.8 mole or less, gelation of the aqueous dispersion by increasing the viscosity is suppressed. More preferably, the upper limit of the amount of the amine is 0.6 mol, 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, in addition to the amine having a boiling point of 100 DEG C or lower, it is also preferable to use a monovalent metal ion for neutralization. It is effective for improving the solvent resistance and the hardness of the coating film. As the compound of the monovalent metal, it is preferable to include one or two or more metals selected from sodium, potassium and lithium, and hydroxides, carbonates or oxides of these metals are preferable. Among them, NaOH, KOH, LiOH and the like are preferable, and NaOH is most preferable because of the best performance.

The amount of the monovalent metal compound is preferably in the range of 0.02 to 0.4 mol (2 to 40 mol%) with respect to 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer. When the amount of the metal is 0.02 mol or more, the emulsion stability becomes better. When the amount of the metal is 0.4 mol or less, the hygroscopicity (particularly to the alkaline solution) of the obtained resin coating is reduced, and the corrosion resistance after the degreasing step is further improved. More preferably, the lower limit of the amount of metal is 0.03 mol, and the more preferable lower limit is 0.1 mol, more preferably the upper limit of the metal amount is 0.3 mol, and the more preferable upper limit is 0.2 mol.

The preferable ranges of the respective amounts of the amine and the monovalent metal compound having a boiling point of 100 DEG C or lower are as described above, but they are all used to neutralize the carboxyl groups in the ethylene-unsaturated carboxylic acid copolymer to make them water-soluble. Therefore, if the total amount (neutralization amount) thereof is excessively large, the viscosity of the aqueous dispersion may rapidly increase and solidify, and the excessive alkali component may cause deterioration in corrosion resistance or require enormous energy for volatilization, I do not. However, if the neutralization amount is too small, the emulsification property is poor, which is also undesirable. Therefore, the total amount of the amine and the monovalent metal having a boiling point of 100 캜 or less is preferably in the range of 0.3 to 1.0 mol per 1 mol of the carboxyl group in the ethylene-unsaturated carboxylic acid copolymer.

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

The amine and the monovalent metal having a boiling point of 100 占 폚 or less may be simultaneously added to the copolymer in the neutralization step (hydroisomerization step) of an amine and an ethylene-unsaturated carboxylic acid copolymer with a monovalent metal ion at a boiling point of 100 占 폚 or less, It is preferable to first add an amine of 100 DEG C or lower. The reason for this is not clear, but if the amine having a boiling point of 100 deg. C or lower is added afterwards, the effect of improving the corrosion resistance may become insufficient.

As the method for preparing the aqueous dispersion of the ethylene-unsaturated carboxylic acid copolymer used in the present invention, an ethylene-unsaturated carboxylic acid copolymer is added to a homogenizer, for example, with an aqueous medium, and if necessary, heated to 70 to 250 캜, An amine having a boiling point of 100 ° C or less and a compound of a monovalent metal are appropriately added in the form of an aqueous solution or the like (an amine having a boiling point of 100 ° C or lower is added first, or an amine and a monovalent metal having a boiling point of 100 ° C or lower are added at about the same time ) And stirred with a high shear force.

1-2. Carboxyl group-containing polyurethane resin aqueous solution

As the aqueous solution of the carboxyl group-containing polyurethane resin used in the present invention, any aqueous dispersion in which the carboxyl group-containing polyurethane resin is dispersed in an aqueous medium or an aqueous solution in which the carboxyl group-containing polyurethane resin is dissolved in an aqueous medium have. The aqueous medium may contain, in addition to water, a small amount of a hydrophilic solvent such as alcohol, N-methylpyrrolidone, or acetone.

The carboxyl group-containing polyurethane resin is preferably obtained by subjecting the urethane prepolymer to chain extension reaction with a chain extender.

The urethane prepolymer is obtained, for example, by reacting a polyisocyanate component and a polyol component described below. Examples of the polyisocyanate component constituting the urethane prepolymer include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and dicyclohexylmethane diisocyanate (hydrogen Addition MDI) is preferably used as the polyisocyanate. By using such a polyisocyanate, a resin film excellent in corrosion resistance and stability of reaction control can be obtained.

In addition to the polyisocyanate, other polyisocyanates may be used within a range that does not deteriorate the corrosion resistance and the stability of the reaction control. Examples of the polyisocyanate other than the polyisocyanate component include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, dodecane methylene diisocyanate, isophoronediisocyanate, Xylene diisocyanate, phenylene diisocyanate, and the like. These polyisocyanates may be used singly or in combination of two or more. When another polyisocyanate is used, the content of the polyisocyanate component (TDI, MDI, and hydrogenated MDI) is preferably 70% by mass or more of the total polyisocyanate component. When the content of these polyisocyanate components is 70 mass% or more, the stability of corrosion resistance and reaction control is further improved.

As the polyol component constituting the urethane prepolymer, it is preferable to use all three polyols such as 1,4-cyclohexane dimethanol, polyether polyol and polyol having a carboxyl group, more preferably all three kinds As a diol. This is because a resin film excellent in corrosion resistance and sliding property can be obtained by using such a polyol component. In addition, by using 1,4-cyclohexane dimethanol as the polyol component, the rust-preventive effect of the obtained polyurethane resin can be enhanced.

The polyether polyol is not particularly limited as long as the polyether polyol has at least two hydroxyl groups in the molecular chain and the main skeleton is composed of alkylene oxide units. Examples thereof include polyoxyethylene glycol (simply referred to as " polyethylene glycol " (Sometimes simply referred to as " polypropylene glycol "), polyoxytetramethylene glycol (simply referred to as " polytetramethylene glycol " or " polytetramethylene ether glycol " And the like, and a commercially available one can be used. Among the polyether polyols, polyoxypropylene glycol or polytetramethylene ether glycol is preferably used. The functional group number of the polyether polyol is not particularly limited as long as it is at least 2, and may be multifunctional, for example, trifunctional or tetrafunctional.

The polyether polyol is obtained, for example, by adding an alkylene oxide such as ethylene oxide, propylene oxide or the like to an initiator. Examples of the compound having an active hydrogen include diols such as propylene glycol and ethylene glycol; Triols such as glycerin, trimethylol propane, hexyl lauryl, triethanolamine and the like; Tetraols such as diglycerin and pentaerythritol; Other examples include sorbitol, sucrose, and phosphoric acid. At this time, when a diol is used as an initiator to be used, a bifunctional polyether polyol is obtained, and when a triol is used, a trifunctional polyether polyol is obtained. Further, polyoxytetramethylene glycol is obtained, for example, by ring-opening polymerization of tetrahydrofuran.

The polyether polyol is preferably commercially available, for example, having a number average molecular weight of about 400 to 4,000. When the number average molecular weight is about 400 or more, the flexibility of the resin coating is improved. When the number average molecular weight is 4000 or less, excessive softening can be suppressed. On the other hand, the number average molecular weight can be obtained by measuring OH (hydroxyl group).

In the present invention, it is also preferable that the mass ratio of 1,4-cyclohexane dimethanol and polyether polyol is 1,4-cyclohexane dimethanol: polyether polyol = 1: 1 to 1: 19 to be. This is because by using a certain proportion of 1,4-cyclohexane dimethanol having an anti-corrosive effect, the anti-corrosive effect of the obtained polyurethane resin coating can be further enhanced.

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, and examples thereof include dimethylolpropionic acid, dimethylolbutanoic acid, dihydroxypropionic acid, dihydroxysuccinic acid and the like have. The amount of the polyol having a carboxyl group may be adjusted depending on the desired hydroxyl group.

In addition to the above three kinds of polyol components, other polyols can be used within a range not lowering the corrosion resistance. In this case, the content of the three kinds of polyol components is preferably 70 mass% or more of the total polyol component. When the content of the three kinds of polyol components is 70 mass% or more, the corrosion resistance is further improved. The polyols other than the above-mentioned three kinds of polyol components are not particularly limited as long as they have a plurality of hydroxyl groups, and examples thereof include low molecular weight polyols and high molecular weight polyols.

The low molecular weight polyol is a polyol having an average molecular weight of about 500 or less, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, Diols such as 6-hexanediol; And triols such as glycerin, trimethylol propane and hexyl lauryl.

The high molecular weight polyol is a polyol having an average molecular weight of more than about 500, for example, condensation polyester polyols such as polyethylene adipate (PEA), polybutylene adipate (PBA) and polyhexamethylene adipate (PHMA); Lactone-based polyester polyols such as poly-epsilon -caprolactone (PCL); Polycarbonate polyols such as polyhexamethylene carbonate and the like; And acrylic polyol.

The chain extender for chain extension reaction of the urethane prepolymer described above is not particularly limited, and examples thereof include polyamines, low molecular weight polyols, alkanolamines and the like. As the low molecular weight polyol, the same ones as mentioned above can be used. Examples of the polyamines include aliphatic polyamines such as ethylene diamine, propylene diamine, and hexamethylene diamine; Aromatic polyamines such as tolylene diamine, xylylenediamine, and diaminodiphenylmethane; Alicyclic polyamines such as diaminocyclohexyl methane, piperazine and isophoronediamine; And hydrazine such as hydrazine, succinic acid dihydrazide, adipic acid dihydrazide, and phthalic acid dihydrazide. Among them, it is preferable to use ethylenediamine and / or hydrazine as a chain extender component. Examples of the alkanolamine include diethanolamine, monoethanolamine, and the like.

The aqueous liquid of the carboxyl group-containing polyurethane resin used in the present invention can be produced by a known method. For example, a method of neutralizing a carboxyl group of a carboxyl group-containing urethane prepolymer with a base and emulsifying and dispersing it in an aqueous medium to effect chain extension reaction; And a method in which a chain extension reaction is carried out by emulsifying and dispersing a carboxyl group-containing polyurethane resin in a high shear force in the presence of an emulsifier. Hereinafter, a method for preparing an aqueous solution of a polyurethane resin will be described based on a method of neutralizing a carboxyl group of a carboxyl group-containing urethane prepolymer with a base and emulsifying and dispersing it in water, but the present invention is not limited to such a method.

First, the isocyanate group-containing isocyanate group-containing isocyanate group-containing isocyanate group-containing isocyanate group-containing isocyanate group-containing isocyanate group-containing urethane prepolymer is prepared by using the above-described polyisocyanate and the above-described polyol. The temperature at which the urethane prepolymer is synthesized is not particularly limited, but it can be synthesized at a temperature of 50 to 200 캜. A known catalyst may be used for the synthesis of the urethane prepolymer. Examples of the catalyst include monoamines such as triethylamine and N, N-dimethylcyclohexylamine; Polyamines such as N, N, N ', N'-tetramethylethylenediamine, N, N, N', N ", N" -pentamethyldiethylenetriamine; Cyclic diamines such as 1,8-diazabicyclo [5.4.0] -7-undecene (DBU) and triethylenediamine; Tin catalysts such as dibutyl tin dilaurate and dibutyl tin diacetate, and the like.

In the synthesis of the urethane prepolymer, the one-shot method may be employed or the prepolymer method may be employed. The one-shot method is a method of collectively reacting a polyisocyanate with a polyol. The pre-poly method is a method of reacting a polyisocyanate with a polyisocyanate in a multistage manner. For example, a urethane prepolymer having a low molecular weight to a medium molecular weight And then further increasing the molecular weight.

In the present invention, for example, a method of collectively reacting both polyisocyanate and the three kinds of polyols; Reacting the polyisocyanate with the polyether polyol among the three polyol components first, followed by further reacting 1,4-cyclohexane dimethanol, and the polyol having a carboxyl group; A urethane prepolymer may be synthesized by suitably selecting a polyol component from the polyether polyol and 1,4-cyclohexane dimethanol, followed by reacting the polyol having a carboxyl group.

In the production of the isocyanate group-terminated urethane prepolymer containing a carboxyl group, it is also a preferred embodiment to use a solvent from the viewpoints of adjusting the viscosity and improving emulsification and dispersibility of the prepolymer. As the solvent, it is preferable to use a solvent which is inert to the isocyanate group and has a relatively high hydrophilicity, and examples thereof include N-methylpyrrolidone, acetone, ethyl acetate, methyl ethyl ketone, N, N- Amide and the like can be used, and N-methylpyrrolidone is preferably used. N-methylpyrrolidone has a high solubility in a polyol having a carboxyl group, and the reaction for preparing an isocyanate-terminated urethane prepolymer can be made uniform. On the other hand, for the reaction of the urethane prepolymer, the reaction rate can be determined by, for example, determining the isocyanate group concentration by a dibutylamine titration method.

After completion of the urethane prepolymer reaction, the resulting carboxyl group-containing isocyanate-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; Hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide and the like can be used, and triethylamine is preferably used.

After the carboxyl group-containing isocyanate-terminated urethane prepolymer is emulsified and dispersed, the chain extension reaction can be carried out in water using a chain extender such as polyamine. On the other hand, the chain extension reaction can be suitably carried out before emulsion dispersion, simultaneous with emulsion dispersion or after emulsion 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. If the acid value is less than 10 mgKOH / g, the stability of the polyurethane resin aqueous dispersion decreases. When the acid value is more than 60 mgKOH / g, the corrosion resistance of the obtained resin coating tends to be lowered. The acid value is measured according to JIS-K0070.

1-3. Amount of resin component

When the total amount of the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion, the nonvolatile resin component of the carboxyl group-containing polyurethane resin aqueous solution and the silica particles described later is 100 parts by mass, The content of the volatile resin component is 20 parts by mass or more, more preferably 25 parts by mass or more, and 45 parts by mass or less, and more preferably 35 parts by mass or less. If the amount of the above-mentioned nonvolatile resin component is too small, the corrosion resistance, alkali-resistance to degreasing, and paintability tend to deteriorate. On the other hand, if the amount of the above-mentioned nonvolatile resin component is excessively large, there is a tendency that the outbreak resistance, the tape peeling resistance and the conductivity are lowered.

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

The mixing ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) to the carboxyl group-containing polyurethane resin (PU) is in the range of EC: PU = 90: 10 to 40:60, preferably 80:20 to 50:50, 50. If the ratio of EC as the blending ratio of the nonvolatile component (EC) of the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion to the nonvolatile component (PU) of the polyurethane resin aqueous solution is larger than 90:10, the tape peeling resistance is deteriorated. On the other hand, if the ratio of EC is smaller than 40:60, the alkali-alkali degreasing property is lowered.

2. Silica particles

The resin aqueous liquid used in the present invention contains silica particles in addition to the aforementioned non-volatile resin component of the ethylenically-unsaturated carboxylic acid copolymer aqueous dispersion and the carboxyl group-containing polyurethane aqueous liquid.

The silica particles impart electrical conductivity, corrosion resistance, and paintability to the resulting resin coating, and increase the hardness of the coating to improve the braking property.

In order to maximize the effect of the silica particles, it is preferable that the average particle diameter of the silica particles is in the range of 4 to 20 nm. 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 resin aqueous solution is lowered to cause gelation It is easy. On the other hand, when the average particle diameter of the silica particles exceeds 20 nm, the film formability of the resin coating is lowered and the corrosion resistance, paintability and alkali resistance to degreasing may be lowered.

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

Examples of commercially available colloidal silica include "Snowtex (registered trademark)" available from Nissan Chemical Industries, "Adelite (registered trademark)" available from ADEKA, and "Silica stone (registered trademark)" available from Nippon Chemical Industry Co., . As the colloidal silica having an average particle diameter of 4 to 6 nm, for example, "SNOWTEX (registered trademark) XS" manufactured by Nissan Chemical Industries, Ltd. and colloidal silica having an average particle diameter of 10 to 20 nm "SNOWTEX (Registered trademark) 40 "," SNOWTEX (registered trademark) N "," SNOWTEX (registered trademark) C ", and ADEKA (registered trademark) AT-30 available from ADEKA.

When the total amount of the non-volatile resin component of the ethylenically-unsaturated carboxylic acid copolymer aqueous dispersion and the carboxyl group-containing polyurethane aqueous solution and the silica particles in the resin aqueous liquid used in the present invention is 100 parts by mass, The content is at least 55 parts by mass, preferably at least 65 parts by mass, and at most 80 parts by mass, preferably at most 75 parts by mass. When the content of the silica particles is less than 55 parts by mass, there is a tendency that the conductivity, the outbreaking resistance and the peeling resistance of the tape are lowered. When the content of the silica exceeds 80 parts by mass, the film formability of the resin film is lowered, and the corrosion resistance and the alkali degreasing property tend to be lowered.

3. Silane coupling agent

The resin aqueous liquid used in the present invention further contains a silane coupling agent. The silane coupling agent is used to increase the adhesion of the metal film to the resin film formed on the metal film, in addition to enhancing the resistance to breakage, paintability, corrosion resistance and the like.

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 general formula (a), the coating property and the corrosion resistance of the resin film to be formed can be enhanced.

(A)

Wherein R ¹ and R ² are an alkoxy group, R ³ is an alkoxy group or an alkyl group having 1 to 4 carbon atoms, and X is an alkylene group having 1 to 5 carbon atoms.

Examples of the alkoxy group represented by R ¹ , R ² and R ³ include a methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, tert- N-hexyloxy group, and the like. Among them, a carbon number of 1 to 4 is preferable, and a methoxy group and an ethoxy group are more preferable. In addition, since the alcohol produced by hydrolysis of the alkoxy group may cause property deterioration if it remains in the film, it is preferable that the methoxy group in which methanol having lower boiling point than the ethoxy group in which ethanol is produced is a methoxy group.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ³ include straight chain alkyl groups such as methyl group, ethyl group, n-propyl group and n-butyl group; A branched alkyl group such as an isopropyl group, an isobutyl group and a tert-butyl group; And cyclic alkyl groups such as cyclopropyl, cyclobutyl and the like. Of these, a straight chain alkyl group is preferable, and a methyl group and an ethyl group are more preferable.

On the other hand, from the viewpoint of solubility in water by hydrolysis of the alkoxy group, the silane coupling agent is preferably trialkoxysilane having three alkoxy groups than the "dialkoxysilane" having two alkoxy groups. Therefore, it is preferable that R ³ is 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. Of these, the number of carbon atoms is preferably 2 to 4.

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

The silane coupling agent represented by the above-mentioned formula (a) is commercially available, and examples thereof include "KBM-402", "KBM-403", "KBE-402", "KBM-402" manufactured by Shinetsu Kagaku Kogyo Co., Z-6040 "," Z-6044 "," Z-6041 "," Z-6042 ", and" Z-6043 "

The content of the silane coupling agent in the resin aqueous solution is 5 parts by mass or more, preferably 10 parts by mass or more and 20 parts by mass or less, and more preferably 20 parts by mass or less, based on 100 parts by mass of the total of the above- 15 parts by mass or less.

When the content of the silane coupling agent is too small, the reactivity of the silica particles with the above-mentioned ethylenically-unsaturated carboxylic acid copolymer or the carboxyl group-containing polyurethane resin is lowered, resulting in deterioration of braiding, paintability and corrosion resistance. On the other hand, if the content of the silane coupling agent is excessively large, the stability of the resin aqueous solution lowers and gelation may occur. In addition, the amount of the silane coupling agent not contributing to the reaction increases, The adhesion of the resin film formed may be lowered.

4. Alkoxysilane

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

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

[Formula b]

Wherein R ⁴ , R ⁵ and R ⁶ are an alkoxy group and R ⁷ is 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 above for R ¹ , R ² and R ³ . Among them, a carbon number of 1 to 4 is preferable, and a methoxy group and an ethoxy group are more preferable. In addition, since the alcohol produced by hydrolysis of the alkoxy group may cause property deterioration if it remains in the film, it is preferable that the methoxy group in which methanol having lower boiling point than the ethoxy group in which ethanol is produced is a methoxy group.

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; Branched alkyl groups such as isopropyl, isobutyl, sec-butyl, isopentyl, sec-pentyl, tert-pentyl, neopentyl, isohexyl, sec-hexyl, ; And cyclic alkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl groups. On the other hand, if 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 into the treatment liquid becomes difficult. Of these, straight-chain alkyl groups are preferred for this reason, and N-hexyl groups are more preferred.

As described above, the alkoxysilane (b) in the present invention is a compound having one specific alkyl group free from a functional group, and includes pentyltrimethoxysilane, pentyltriethoxysilane, hexyltrimethoxysilane , Hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, and the like. In the present invention, one or more of these may be used. Among them, hexyltrimethoxysilane is particularly preferable.

The above alkoxysilane (b) is commercially available, and examples thereof include "KBM3033", "KBM3063", "KBE3063" manufactured by Shinetsu Kagaku Kogyo Co., Ltd., "Z-6582", "Z- -6586 " and the like.

The content of the alkoxysilane (b) in the resin aqueous solution is 1 part by mass or more, preferably 3 parts by mass or more, and 14 parts by mass or less, Or less, preferably 12 parts by mass or less.

When the content of the alkoxysilane (b) is too small, the affinity of the silica particles with the ethylenically-unsaturated carboxylic acid copolymer or the carboxyl group-containing polyurethane resin decreases, and the corrosion resistance and alkali-alkali rusting property are lowered . On the other hand, if the content of the alkoxysilane is too large, the stability of the resin aqueous solution lowers and gelation may occur, and adhesiveness such as paintability and tape peelability deteriorates.

5. Other additives

The above-mentioned ethylene-unsaturated carboxylic acid copolymer having an amine having a boiling point of 100 DEG C or lower and a carboxyl group neutralized with a monovalent metal ion forms an intermolecular association by ion clusters (ionomerization) to form a resin film excellent in corrosion resistance do. However, in order to form a stronger film, it is preferable to cross-link the polymer chains by chemical bonding using a reaction between functional groups. Thus, the aqueous dispersion of the ethylene-unsaturated carboxylic acid copolymer used in the present invention preferably contains a crosslinking agent having two or more functional groups capable of reacting with the carboxyl group.

The content of the crosslinking agent is preferably not less than 1 part by mass, more preferably not less than 5 parts by mass, and not more than 20 parts by mass, based on 100 parts by mass of the nonvolatile resin component (EC) in the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion And preferably not more than 10 parts by mass.

When the amount is 1 part by mass or more, the effect of crosslinking by chemical bonding becomes better, and the effect of improving the corrosion resistance is further exerted. On the other hand, when the amount is less than 20 parts by mass, the crosslinking density of the resin film becomes excessively high, so that the increase in hardness is suppressed, and the resin film can be also followed by deformation during press working. Therefore, the occurrence of cracks during press working is suppressed, and as a result, corrosion resistance and paintability are further improved.

The crosslinking agent having two or more functional groups capable of reacting with the carboxyl group in the molecule is not particularly limited, and examples thereof include sorbitol polyglycidylether, (poly) glycerol polyglycidylether, pentaerythritol polyglycidyl Polyglycidyl ethers such as trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether and (poly) ethylene glycol diglycidyl ether, polyglycidyl amines such as poly (Ethyleneiminocarbonylamino) diphenylmethane, N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide), N , N'-diphenylmethane-4,4'-bis (1-aziridine carboxamide), and toluene bis aziridine carboxamide; (2-methyl) aziridinyl] phosphine oxide, trimethylolpropanol (? -Aziridinylpropionate), tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, and tetramethylpropane tetraaziridinyl propionate, or derivatives thereof, as azo compounds having an aziridine group as a suitable example And one or more of these can be used. Among them, a crosslinking agent containing an aziridine group is preferable. On the other hand, multifunctional aziridine and monofunctional aziridine (ethyleneimine, etc.) may be used in combination.

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

The average particle diameter of the spherical polyolefin wax particles for efficiently exhibiting lubricity is preferably at least 0.6 mu m, more preferably at least 1 mu m. However, if the average particle diameter of the polyolefin wax particles is excessively large, the coating film adhesion may deteriorate. Therefore, the average particle diameter of the spherical polyolefin wax particles is preferably 4 占 퐉 or less, and more preferably 3 占 퐉 or less. The average particle diameter of the spherical polyolefin wax particles can be measured by the Coulter counter method.

As the spherical polyolefin wax particles, there may be mentioned, for example, a " Chemipel (registered trademark) " series (polyolefin aqueous dispersion) manufactured by Mitsui Chemicals, 500, W-700 and W-900.

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

The surface treatment composition may further contain additives such as a diluent, a skinning inhibitor, a surfactant, an emulsifier, a dispersing agent, a leveling agent, a defoaming agent, a penetrating agent, a film forming aid, a dye, a pigment, ≪ / RTI >

6. Preparation method of resin aqueous solution

The method for preparing the aqueous resin solution is not particularly limited, and examples of the aqueous dispersion of the ethylenically-unsaturated carboxylic acid copolymer, the carboxyl group-containing polyurethane aqueous solution, the silica particles, the silane coupling agent (a), the alkoxysilane (b ), And, if necessary, a predetermined amount of wax, a cross-linking agent, and the like. The silica particles, the silane coupling agent (a), the alkoxysilane (b), the wax, and the crosslinking agent may be added at any stage, but after the addition of the crosslinking agent and the silane coupling agent (a) It is preferable not to apply heat. Further, it is preferable that heat is not applied even when the aqueous liquid is stored from the above-mentioned circumstances, and it is preferable to store it at 30 占 폚 or lower, preferably 20 占 폚 or lower.

In preparing the treatment liquid, a small amount of an organic solvent may be added to lower the interfacial tension to 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, propylene glycol and the like.

7. Metal plate

The metal plate used in the present invention is not particularly limited, such as a steel plate, an aluminum plate, and a Ti plate, but is preferably a zinc plated steel plate. For example, hot-dip galvanized steel sheets, galvannealed galvanized steel sheets, molten Zn-5% Al coated steel sheets, molten Zn-55% Al coated steel sheets, galvanized steel sheets, have. Also, before forming the resin coating, the surface of the metal sheet may be treated with Co or Ni, inhibitor treatment, or various non-chromate undercoating treatment.

8. Method of forming resin film

In order to form the resin coating on the metal sheet, the resin aqueous solution may be coated on one side or both sides of the metal sheet surface by a known coating method such as roll coating method, spraying method, curtain flow coating method and the like. The heating and drying temperature is preferably carried out at a temperature at which water in the aqueous liquid sufficiently evaporates. When a spherical polyethylene wax is used as the lubricant, it is preferable to keep the spherical shape in the range of 70 to 130 캜, since the workability in the later working step is improved.

The adhesion amount (thickness) of the resin film to the metal sheet is 0.05 g / m ² or more, more preferably 0.2 g / m ² or more, and 1 g / m ² or less, and more preferably 0.5 g / m ² or less desirable. When the adhesion amount is too small, the resistance to abrasion, corrosion resistance, and alkali resistance is deteriorated. On the other hand, if the adhesion amount is excessively large, the conductivity and the coating property tend to be lowered. The surface-treated metal sheet may be used after it has been subjected to a processing step according to its use, or by electrodeposition coating, powder coating or silk printing (130 to 160 ° C for about 20 to 30 minutes) under conventional conditions.

[Example]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but it should be understood that the present invention is not limited by the following examples, but may be appropriately modified and carried out within the scope of the prior art and the latter All of which are included in the technical scope of the present invention.

[Assessment Methods]

1. Corrosion resistance

The obtained surface-treated metal plate (resin-coated steel plate) was subjected to a salt water spray test of an edge-sealed flat plate material in accordance with JIS Z2371, and evaluated according to the time until 5% of white rust was generated.

Evaluation standard

◎: more than 240 hours of white rust occurrence

○: Occurrence of white rye more than 120 hours ~ less than 240 hours

△: White rust occurrence 72 hours to less than 120 hours

X: Less than 72 hours of white rust occurrence

2. Alkali degreasing resistance

The test piece was immersed in 20 g / l of an alkaline degreasing agent ("L-4460", manufactured by Nippon Packerizing Co., Ltd.) adjusted to a liquid temperature of 60 ° C for 2 minutes, and was then rinsed with water and dried. Then, the test piece was subjected to a salt spray test according to JIS Z2371 Was carried out to evaluate the time until the 1% white rust was generated.

Evaluation standard

◎: 168 hours or more

○: 96 hours or more and less than 168 hours

△: 48 hours or more and less than 96 hours

×: Less than 48 hours

3. Conductivity

The surface resistance of the obtained surface-treated metal plate (resin-coated steel sheet) was measured at 10 points by a surface resistance meter (Loresta (registered trademark) -EP, 4 terminal 4 probe method, manufactured by DAIYA INSTRUMENTS CO., LTD.).

Evaluation standard

◎: Overload 0 times at less than 1mΩ / 10 places

○: Overload at 1mΩ or less / 10 points

Δ: Overload 2 times or more and 4 times or less at 1mΩ or less / 10 places

×: Overload more than 5 times at 1mΩ or more / 10 places

4. Painting ability

A spray coating was applied to the obtained surface-treated metal plate (resin-coated steel plate) so that the film thickness after drying was about 20 μm, and melamine alkyd paint ("AMILAC (registered trademark) # 1000" For 20 minutes. Subsequently, this specimen was immersed in boiling water for 1 hour, then taken out and allowed to stand for 1 hour. Thereafter, a checkerboard eye of 1 mm square was cut with a cutter knife by 100 scoops. The adhesion of the coating film was evaluated in four steps by the number of grids.

Evaluation standard

?: Remaining ratio: 100%

○: Remaining ratio: 90% or more to less than 100%

?: Residual ratio: 80% or more to less than 90%

X: Remaining ratio: 70% or more to less than 80%

5. Breathing

The obtained surface-treated metal plate (resin-coated steel plate) was subjected to a vibration test in accordance with a blanket-vibration test (JIS Z0232), and the appearance of the test piece after a predetermined period of time was evaluated based on the following criteria. On the other hand, the vibration testing apparatus used was the trade name " BF-500UC "

Evaluation standard

◎: No damage to the film

○: Damage to the coating, but no damage to the galvanized surface

△: There is visible damage to the surface of galvanized metal

X: The surface of zinc plating is markedly damaged

6. My tape peelability

A filament tape ("Filament Tape # 9510" manufactured by Marxell-Liontech Co., Ltd.) was attached to the surface of the sealing material, and the filament tape was peeled off after being stored for 120 hours in an atmosphere of 40 ° C. × RH 98%, and the ratio of the area (Residual ratio) was measured.

Evaluation standard

◎: Remaining rate 100%

○: Residual ratio 90% or more and less than 100%

?: Residual rate 80% or more and less than 90%

X: Less than 80% of residual ratio

Preparation of aqueous dispersion of ethylene-unsaturated carboxylic acid copolymer

(Acrylic acid: 20 mass%, melt index (MI): 300 g / 10 min (190 deg. C, 2.16 kg) was added to an autoclave having an internal volume of 0.8 L equipped with a stirrer, a thermometer and a temperature controller, ), And 0.4 mol (40 mol%) of triethylamine and 0.15 mol (15 mol%) of sodium hydroxide were added to 1 mol of the carboxyl group of the ethylene-acrylic acid copolymer. The resulting mixture was stirred at a high temperature of 150 ° C under an atmosphere of 5 Pa and cooled to 40 ° C to obtain an aqueous dispersion of an ethylene-acrylic acid copolymer. Subsequently, 4,4'-bis (ethyleneiminocarbonylamino) diphenylmethane ("Chemitite (registered trademark) DZ-2E" manufactured by Nippon Catalyst Co., Ltd.) was added as the crosslinking agent to the aqueous dispersion, Was added so as to be a ratio of 5 parts by mass based on 100 parts by mass of the nonvolatile resin component.

Carboxyl group  Of water-containing polyurethane resin

A stirrer, a thermometer and a temperature controller was charged with 60 g of polytetramethylene ether glycol (manufactured by Hodogaya Chemical Co., Ltd., number average molecular weight 1000) as a polyol component, 14 g of 1,4-cyclohexane dimethanol , 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 mixture was heated from 80 DEG C to 85 DEG C and allowed to react for 5 hours. The NCO content of the obtained prepolymer was 8.9% by mass. Further, 16 g of triethylamine was added to neutralize, and a mixed aqueous solution of 16 g of ethylenediamine and 480 g of water was added and emulsified at 50 DEG C for 4 hours, and subjected to chain extension reaction to obtain an aqueous polyurethane resin dispersion (29.1% of a nonvolatile resin component, , Acid value 41.4 mgKOH / g).

Preparation of resin aqueous solution and preparation of surface treated metal sheet

Experimental Example 1

An aqueous dispersion of a carboxyl group-containing polyurethane resin, an aqueous dispersion of an ethylene-acrylic acid copolymer and silica particles ("SNOWTEX (registered trademark) XS", average particle diameter (BET method) 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.) 100 parts by mass in total in terms of the nonvolatile component were blended so as to obtain the blending ratio shown in Table 1. 1 part by mass of this total was further mixed with? -Glycidoxypropyltrimethoxysilane (Shinetsu Kagaku Kogyo Co., Ltd.) as a silane coupling agent, KBM-403 ") and 6 parts by mass of hexyltrimethoxysilane (KBM-3063, manufactured by Shin-Etsu Chemical Co., Ltd.) as an alkoxysilane were added to prepare a resin aqueous solution.

This resin aqueous solution was applied to the surface of the galvanized steel sheet with a tightening roll and heated and dried at a plate temperature of 90 DEG C to obtain a surface-treated metal sheet (resin-coated steel sheet) having a resin coating film with an adhesion amount of 0.5 g / m ² . The obtained resin-coated steel sheets were evaluated for corrosion resistance, conductivity, resistance to braking, alkali resistance to degreasing, paintability and the like, and the results are shown in Table 1.

On the other hand, an electro-galvanized steel sheet (Zn deposition amount: 20 g / m ² , plate thickness: 0.8 mm) without chromate treatment was used as the galvanized steel sheet.

Steel plate No. 4 to 9, and 14 to 18, the resin aqueous solution contains 20 to 45 parts by mass of the nonvolatile resin component and 55 to 80 parts by mass of the silica particles in a total amount of 100 parts by mass, and the nonvolatile resin component is an ethylene-unsaturated carboxylic acid (EC) of a copolymer aqueous dispersion and a nonvolatile resin component (PU) of an aqueous solution of a carboxyl group-containing polyurethane resin, wherein the compounding ratio is EC: PU = 90: 10 to 40: 60. It can be seen that these steel sheets have excellent corrosion resistance, alkali resistance to degreasing, conductivity, paintability, resistance to braking, and resistance to peeling of the tape.

Steel plate No. In Examples 1 to 3, the proportion of the nonvolatile resin component was less than 20 parts by mass, and the corrosion resistance and alkali alkali rust resistance deteriorated.

Steel plate No. 10, and 11 were cases where the ratio of the nonvolatile resin component exceeded 45 parts by mass, and the conductivity, abrasion resistance, and peeling resistance of the tape deteriorated.

Steel plate No. 12 and 13 were cases where the proportion of EC in the nonvolatile resin component was excessively high and the peelability of the tape was deteriorated.

Steel plate No. 19, and 20, the proportion of PU in the nonvolatile resin component was excessively high, and the alkali-alkali degreasing property deteriorated.

Experimental Example 2

The aqueous solution of the carboxyl group-containing polyurethane resin obtained above, the aqueous dispersion of the ethylene-acrylic acid copolymer, and the silica particles were blended so that the nonvolatile resin component was 30 parts by mass and the silica particles were 70 parts by mass in total, (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as 0 to 30 parts by mass of γ-glycidoxypropyltrimethoxysilane as a silane coupling agent, 100 parts by mass of hexyltrimethoxysilane as an alkoxysilane (KBM-3063, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to prepare a resin aqueous solution. On the other hand, as the silica particles, "SNOWTEX XS" (average particle diameter (BET method) of 4 to 6 nm) manufactured by Nissan Chemical Industries, Ltd. was used and the ethylene-unsaturated carboxylic acid copolymer (EC) in the nonvolatile resin component and the carboxyl group-containing polyurethane resin (PU) was determined as EC: PU = 70:30 by mass ratio.

This resin aqueous solution was applied to the surface of the galvanized steel sheet with a tightening roll and heated and dried at a plate temperature of 90 DEG C to obtain a surface-treated metal sheet (resin-coated steel sheet) having a resin coating film with an adhesion amount of 0.5 g / m ² . The resin coated steel sheet thus obtained was evaluated on the composition of the resin film, the corrosion resistance, the conductivity, the weather resistance, the alkali resistance to degreasing, the paintability and the like.

On the other hand, an electro-galvanized steel sheet (Zn deposition amount: 20 g / m ² , plate thickness: 0.8 mm) without chromate treatment was used as the galvanized steel sheet.

Steel plate No. 6, and 22 to 25, the resin aqueous solution contains 5 to 20 parts by mass of the silane coupling agent (a) and 6 parts by mass of the alkoxysilane (b) per 100 parts by mass of the total of the nonvolatile resin component and the silica particles , It can be seen that any of the steel sheets is excellent in corrosion resistance, alkali resistance to degreasing, conductivity, paintability, resistance to braking, and resistance to peeling of the tape.

On the other hand, the steel sheet No. 3 containing no silane coupling agent (a). 21, the corrosion resistance, alkali resistance to degreasing, paintability, resistance to braking, and resistance to peeling of the tape deteriorated.

Further, the addition amount of the silane coupling agent (a) is too large. 26, and 27, the paintability, outbreak resistance, and peel resistance of the inner tape deteriorated.

Experimental Example 3

The aqueous solution of the carboxyl group-containing polyurethane resin obtained above, the aqueous dispersion of the ethylene-acrylic acid copolymer, and the silica particles were blended so that the nonvolatile resin component was 30 parts by mass and the silica particles were 70 parts by mass in total, 12 parts by mass of? -Glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent and 12 parts by mass of hexyltrimethoxysilane as alkoxysilane (KBM-3063, manufactured by Shin-Etsu Chemical Co., Ltd.) was added in an amount of 0 to 20 parts by mass to prepare a resin aqueous solution. On the other hand, as the silica particles, "SNOWTEX XS" (average particle diameter (BET method) 4 to 6 nm) manufactured by Nissan Chemical Industries Co., Ltd. was used, and an ethylene-unsaturated carboxylic acid copolymer (EC) in the nonvolatile resin component and a carboxyl group- The compounding ratio of the resin (PU) was set to EC: PU = 70:30 by mass ratio.

This resin aqueous solution was applied to the surface of the galvanized steel sheet with a tightening roll and heated and dried at a plate temperature of 90 DEG C to obtain a surface-treated metal sheet (resin-coated steel sheet) having a resin coating film with an adhesion amount of 0.5 g / m ² . Table 3 shows the results of evaluating the composition of the resin film, the corrosion resistance, the conductivity, the resistance to abrasion, the alkali resistance to degreasing, the paintability and the like of the resin coated steel sheet obtained.

On the other hand, an electro-galvanized steel sheet (Zn deposition amount: 20 g / m ² , plate thickness: 0.8 mm) without chromate treatment was used as the galvanized steel sheet.

Steel plate No. 6, and 29 to 33, the resin aqueous solution was prepared by mixing 12 parts by mass of the silane coupling agent (a) and 1 to 14 parts by mass of the alkoxysilane (b) per 100 parts by mass of the total of the nonvolatile resin component and the silica particles It can be seen that any of the steel sheets is excellent in corrosion resistance, alkali resistance to degreasing, conductivity, paintability, resistance to breakage, and resistance to peeling of the tape.

On the other hand, the steel sheet No. 3 containing no alkoxysilane (b). 28, the corrosion resistance and the alkali resistance to degreasing deteriorated.

Further, the amount of the alkoxysilane (b) to be added is too large. 34, and 35, the corrosion resistance, alkali resistance to rust resistance, paintability, resistance to braking, and peelability of the inner tape deteriorated.

Experimental Example 4

The above-obtained aqueous polyurethane resin solution, the ethylene-acrylic acid copolymer aqueous dispersion and silica particles having an average particle diameter of 4 to 100 nm ("SNOWTEX" series manufactured by Nissan Chemical Industries, Ltd.) were mixed with 30 parts by mass of a non- (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent was added to 100 parts by mass of the total of 100 parts by mass of a total of 100 parts by mass of silica particles And 6 parts by mass of hexyltrimethoxysilane (KBM-3063, Shin-Etsu Chemical Co., Ltd.) as an alkoxysilane were added to prepare a resin aqueous solution. On the other hand, the mixing ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) in the nonvolatile resin component to the carboxyl group-containing polyurethane resin (PU) was set to EC: PU = 70:30 in a mass ratio.

This resin aqueous solution was applied to the surface of the galvanized steel sheet with a tightening roll and heated and dried at a plate temperature of 90 DEG C to obtain a surface-treated metal sheet (resin-coated steel sheet) having a resin coating film with an adhesion amount of 0.5 g / m ² . The obtained resin-coated steel sheet was evaluated on the composition of the resin film, the corrosion resistance, the conductivity, the weather resistance, the alkali resistance to degreasing, the paintability and the like.

On the other hand, an electro-galvanized steel sheet (Zn deposition amount: 20 g / m ² , plate thickness: 0.8 mm) without chromate treatment was used as the galvanized steel sheet.

Steel plate No. 36 and 37 show that the average particle diameter of the silica particles is 4 to 6 nm or 10 to 20 nm and that any of the steel sheets is excellent in corrosion resistance, alkali resistance to degreasing, conductivity, paintability, resistance to braking, have.

On the other hand, when the average particle diameter of the silica particles is 40 to 60 nm or 70 to 100 nm, 38, and 39, the alkali resistance was deteriorated, the conductivity, the paintability, the bare breaking property, and the peeling resistance of the inner tape were deteriorated.

Experimental Example 5

The aqueous polyurethane resin solution, the ethylene-acrylic acid copolymer aqueous dispersion and the silica particles (SNOWTEX XS, average particle diameter (BET method) 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.) 30 parts by mass, and silica particles in an amount of 70 parts by mass in total were mixed in a total amount of 100 parts by mass, and 12 parts by mass of the silane coupling agent shown in Table 5 was added to 100 parts by mass of the total amount, hexyltrimethoxysilane ( Manufactured by Shin-Etsu Chemical Co., Ltd., " KBM-3063 ") was added to prepare a resin aqueous solution. On the other hand, the mixing ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) in the nonvolatile resin component to the carboxyl group-containing polyurethane resin (PU) was set to EC: PU = 70:30 in a mass ratio.

This resin aqueous solution was applied to the surface of the galvanized steel sheet with a tightening roll and heated and dried at a plate temperature of 90 DEG C to obtain a surface-treated metal sheet (resin-coated steel sheet) having a resin coating film with an adhesion amount of 0.5 g / m ² . The obtained resin-coated steel sheets were evaluated for composition, corrosion resistance, electrical conductivity, resistance to weathering, alkali resistance to degreasing, paintability, etc. of the resin coatings.

On the other hand, an electro-galvanized steel sheet (Zn deposition amount: 20 g / m ² , plate thickness: 0.8 mm) without chromate treatment was used as the galvanized steel sheet.

As shown in Table 5, the steel sheet No. 1 using the compound other than the silane coupling agent represented by the general formula a. From 42 to 44, the stability of the resin aqueous solution was poor, and a resin film could not be formed.

Experimental Example 6

The aqueous polyurethane resin solution, the ethylene-acrylic acid copolymer aqueous dispersion and the silica particles (SNOWTEX XS, average particle diameter (BET method) 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.) 30 parts by mass of silica particles and 70 parts by mass of silica particles in total were mixed in a total amount of 100 parts by mass. To 100 parts by mass of this total, γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM -403 ") and 6 parts by mass of alkoxysilane shown in Table 6 were added to prepare a resin aqueous solution. On the other hand, the mixing ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) in the nonvolatile resin component to the carboxyl group-containing polyurethane resin (PU) was set to EC: PU = 70:30 in a mass ratio.

This resin aqueous solution was applied to the surface of the galvanized steel sheet with a tightening roll and heated and dried at a plate temperature of 90 DEG C to obtain a surface-treated metal sheet (resin-coated steel sheet) having a resin coating film with an adhesion amount of 0.5 g / m ² . The resin coated steel sheet thus obtained was evaluated on the composition of the resin film, the corrosion resistance, the conductivity, the bare breaking resistance, the alkali resistance to degreasing, the paintability and the like.

On the other hand, an electro-galvanized steel sheet (Zn deposition amount: 20 g / m ² , plate thickness: 0.8 mm) without chromate treatment was used as the galvanized steel sheet.

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

Experimental Example 7

The aqueous polyurethane resin solution, the ethylene-acrylic acid copolymer aqueous dispersion and the silica particles (SNOWTEX XS, average particle diameter (BET method) 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.) 30 parts by mass of silica particles and 70 parts by mass of silica particles in total were mixed in a total amount of 100 parts by mass. To 100 parts by mass of this total, γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM -403 ") and 6 parts by mass of hexyltrimethoxysilane (" KBM-3063 ", Shin-Etsu Chemical Co., Ltd.) as an alkoxysilane were added to prepare a resin aqueous solution. On the other hand, the mixing ratio of the ethylene-unsaturated carboxylic acid copolymer (EC) in the nonvolatile resin component to the carboxyl group-containing polyurethane resin (PU) was set to EC: PU = 70:30 in a mass ratio.

Pressure roll coated with a resin aqueous solution to the surface of the electro-galvanized steel sheet in order, and then heated and dried at plate temperature of 90 ℃, coating weight by changing the clamping pressure of the roll surface treated film formed of the resin 0.05~2.0g / m ² To obtain a metal plate (resin-coated steel plate). The obtained resin-coated steel sheet was evaluated on the composition of the resin film, the corrosion resistance, the conductivity, the weather resistance, the alkali resistance to degreasing, the paintability and the like.

On the other hand, an electro-galvanized steel sheet (Zn deposition amount: 20 g / m ² , plate thickness: 0.8 mm) without chromate treatment was used as the galvanized steel sheet.

As shown in Table 7, when the adhesion amount of the resin film on the metal plate is in the range of 0.05 to 1 g / m ^2, the surface-treated metal plate having excellent corrosion resistance, alkali alkali rust resistance, conductivity, paintability, .

The surface-treated metal sheet of the present invention can be suitably used for automobiles, household appliances, building materials, etc., because it has excellent corrosion resistance, alkali-alkali degreasing property, conductivity, paintability (coating film adhesion property), outbreak resistance and peel resistance.

Claims (7)

A surface-treated metal plate comprising a metal plate and a resin coating obtained from an aqueous resin solution formed on at least one side of the metal plate,
The resin aqueous solution 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 is 100 parts by mass,
(EC) of an aqueous dispersion of an ethylene-unsaturated carboxylic acid copolymer and a nonvolatile resin component (PU) of an aqueous solution of a carboxyl group-containing polyurethane resin as the above-mentioned nonvolatile resin component, EC: PU = 90: 10 to 40: 60,
Further, it is preferable that 5 to 20 parts by mass of the silane coupling agent represented by the general formula (a) and 1 to 14 parts by mass of the alkoxysilane represented by the general formula (b) are added to 100 parts by mass of the total of the nonvolatile resin component and the silica particles,
Wherein the adhesion amount of the resin coating is 0.05 to 1 g / m ² .
(A)

Wherein R ¹ and R ² represent a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, Hexyloxy group, R ³ is any one of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, And X represents an alkylene group having 1 to 5 carbon atoms.
[Formula b]

Wherein R ⁴ , R ⁵ and R ⁶ are each independently selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert- And n-hexyloxy group, and R ⁷ represents an alkyl group having 5 to ⁷ carbon atoms. The method according to claim 1,
Wherein the alkoxysilane represented by the formula (b) is hexyltrimethoxysilane. The method according to claim 1,
Wherein the ethylene-unsaturated carboxylic acid copolymer is copolymerized with an unsaturated carboxylic acid component in an amount of from 10 to 40% by mass based on 100% by mass of the total monomer. The method according to claim 1,
Wherein the ethylene-unsaturated carboxylic acid copolymer aqueous dispersion contains a cross-linking agent having two or more functional groups capable of reacting with a carboxyl group, the content of the cross-linking agent being such that the content of the non-volatile resin component in the aqueous dispersion of the ethylene- EC) of not less than 1 part by mass and not more than 20 parts by mass based on 100 parts by mass of the inorganic filler. The method according to claim 1,
The resin aqueous liquid preferably contains 0.5 to 5 parts by mass of spherical polyolefin wax particles having an average particle diameter of not less than 0.6 占 퐉 and not more than 4 占 퐉 per 100 parts by mass of the total mass of the nonvolatile resin component and the silica particles, . 6. The method according to any one of claims 1 to 5,
Wherein the metal plate is a zinc plated steel plate. The method according to claim 6,
Wherein the non-chromate treatment is performed on the metal plate.