JP5411585B2 - Multi-layer surface-treated galvanized steel sheet - Google Patents

Description

  The present invention relates to a multilayer surface-treated zinc-based plated steel sheet excellent in corrosion resistance, adhesion, antifouling property, film-forming property, ultraviolet resistance, alkali resistance, acid resistance and blackening resistance.

  Zinc-based galvanized steel sheets are widely used for building materials, home appliances, automobiles and the like from the viewpoint of excellent corrosion resistance. Because it is used unpainted for building materials and home appliances, it has not only excellent corrosion resistance, but also the color of the plated steel sheet without being affected by ultraviolet irradiation, acid rain, or adsorption of contaminants. It is required to maintain a beautiful appearance that takes advantage of In addition, it is necessary that the surface color tone does not change without being discolored even when exposed to a high-temperature and high-humidity environment typified by long-time sea transportation. In addition, when top coating is applied, sufficient adhesion with the top coating is required. If the adhesion with the overcoating is insufficient, corrosion resistance, acid resistance and alkali resistance are not exhibited.

  Conventionally, as a technology for imparting corrosion resistance, workability, etc. to the surface of metal materials, resin chromate treatment with a treatment liquid containing organic resin and chromic acid, dichromic acid or salts thereof as main components is carried out on the surface of metal materials. Although the application method has been common, at present, environmentally friendly non-chromate organic resin film treatment in which chromium is replaced with another crosslinkable metal has been put to practical use.

  As a non-chromate organic resin film treatment technology, Patent Document 1 discloses a high weather resistance characterized by emulsion polymerization of a monomer composition containing at least a (meth) acrylic acid ester, a dialkyl (meth) acrylamide, and a surfactant. A method for producing a reactive emulsion is disclosed. However, the high weather resistance emulsion produced by the above method does not have sufficient corrosion resistance when a film is formed on a steel sheet and used for non-coating purposes, and even if the film is overcoated. Since sufficient adhesion cannot be obtained, acid resistance and alkali resistance cannot meet the required performance.

  As a non-chromate organic resin film treatment technique, Patent Document 2 discloses at least (meth) acrylic acid ester, 0.1 to 20% by mass of styrene with respect to the (meth) acrylic acid ester, and a surfactant. Disclosed is a method for producing a fine particle emulsion, which comprises emulsion polymerization of a monomer composition comprising However, since the fine particle emulsion produced by the above method contains styrene, the film deteriorates and discolors when irradiated with ultraviolet rays, so that it is unsuitable for outdoor non-painting applications.

  As a non-chromate organic resin film treatment technique, Patent Document 3 further discloses a metal surface treatment agent containing a water-soluble zirconium compound, a water-soluble or water-dispersible acrylic resin, and a water-soluble or water-dispersible thermosetting crosslinking agent. The concentration of the water-soluble zirconium compound is 500 to 15000 ppm on a mass basis as zirconium, the solid content acid value of the acrylic resin is 150 to 740 mg KOH / g, the solid content hydroxyl value is 24 to 240, and the acrylic resin Disclosed is a metal surface treatment agent characterized in that the concentration of the resin is 500 to 30000 ppm on a mass basis as a solid content, and the concentration of the thermosetting crosslinking agent is 125 to 7500 ppm on a mass basis as a solid content. Yes. However, the thermosetting crosslinking agent lacks workability because it cures the film. Furthermore, melamine resins and phenol resins listed as thermosetting crosslinking agents are not suitable for non-coating applications because the film deteriorates and discolors when irradiated with ultraviolet rays.

  As the non-chromate organic resin film treatment technology, Patent Document 4 further discloses (A) an aqueous resin having a carboxyl group and an acid amide bond, (B) Al, Mg, Ca, Zn, Ni, Co, Fe, Zr, What is claimed is: 1. A surface treatment agent for a metal plate material containing no chromium, comprising one or more metal compounds selected from metal compounds of Ti, V, W, Mn and Ce, and (C) a silicon compound. It is disclosed. However, an aqueous resin having an acid amide bond is poor in storage stability because of its strong reactivity with metal compounds and silicon compounds.

  As a non-chromate organic resin film technology, Patent Document 5 further describes (A) a polymerizable unsaturated monomer (such as a styrenic monomer) containing no epoxy group, acid group, hydroxyl group or hydrolyzable silyl group (a ), An epoxy group-containing polymerizable unsaturated monomer (b), an acid group-containing polymerizable unsaturated monomer (c), a hydroxyl group-containing polymerizable unsaturated monomer (d), and a polymer having a hydrolyzable silyl group Water dispersible resin composition containing a copolymer resin emulsion obtained by emulsion polymerization of an unsaturated monomer mixture comprising a polymerizable unsaturated monomer (e), (B) a zirconium compound, and (C) a silane coupling agent A water-dispersible resin treatment agent for metal surfaces is disclosed. However, since the copolymer resin in the film formed with the water-dispersible resin treatment agent for metal surface contains components derived from a styrene monomer and a polymerizable unsaturated monomer having an epoxy group, the film is irradiated by ultraviolet irradiation. Since it deteriorates and discolors, it also lacks antifouling properties and is unsuitable for outdoor non-painting applications. Furthermore, since the polymerizable unsaturated monomer (b) having an epoxy group and the acid group-containing polymerizable unsaturated monomer (c) are highly reactive, the water-dispersible resin treatment agent lacks storage stability.

  As the non-chromate organic resin film technology, Patent Document 6 further describes 0.1 to 30% by mass of a specific nitrogen-containing radically polymerizable unsaturated monomer (a) based on the total amount of constituent monomers. 1 to 20% by mass of a carboxyl group-containing radically polymerizable unsaturated monomer (b), and 50 to 98.9% by mass of another radically polymerizable unsaturated monomer (c) Water-based paint containing 0.01 to 10 parts by mass of the organic acid catalyst (C) with respect to 100 parts by mass of the solid content of the resin component (A) and the resin component (A) obtained by radical polymerization reaction of the mixture Is disclosed. However, the film formed of the water-based paint has insufficient corrosion resistance and cannot meet the required performance.

  In addition, Patent Document 7 discloses an aqueous resin composition containing a polymer of a polymerizable monomer containing a polycyclic alicyclic hydrocarbon ring.

JP 2000-327704 A JP 2000-327722 A JP 2002-275648 A JP 2003-201579 A JP 2006-52348 A JP 2006-152056 A JP 2000-336232 A

As described above, none of the above-described methods and surface treatment agents can meet the required performance, and have performance that can be used as a substitute for the resin chromate film, and have corrosion resistance, adhesion, antifouling properties, and film-forming properties. Therefore, there is a strong demand for the development of a surface-treated steel sheet excellent in ultraviolet resistance, alkali resistance, acid resistance and blackening resistance.
The present invention solves the above-mentioned problems of the prior art, and is a surface-treated zinc-based plating excellent in corrosion resistance, adhesion, antifouling properties, film-forming properties, ultraviolet resistance, alkali resistance, acid resistance and blackening resistance. The object is to provide a steel sheet.

  As a result of intensive studies to solve these problems, the present inventors have found that a base treatment layer containing specific metal ions and / or atoms on at least one surface of a galvanized steel sheet, and a specific polymerization unit are provided. The surface-treated galvanized steel sheet that has two surface treatment layers consisting of an upper treatment layer containing an acrylic resin that exhibits unique film properties has corrosion resistance, adhesion, antifouling properties, film-forming properties, and ultraviolet resistance. The present invention has been completed by finding that it is excellent in water resistance, alkali resistance, acid resistance and blackening resistance.

That is, the present invention provides a multi-layer surface-treated zinc having two surface treatment layers consisting of a base treatment layer (X) and an upper treatment layer (Y) covering the ground treatment layer (X) on at least one surface of a zinc-based plated steel sheet. A metal ion and / or atom in which the base treatment layer (X) is an ion and / or atom of at least one metal selected from the group consisting of Zr, Ti, Hf, Ce, La and Bi. It is an inorganic coating layer containing (A), and the upper treatment layer (Y) is a polymer unit from (meth) acrylic acid ester (b1) represented by the following general formula (I), represented by the following general formula (III) A polymerized unit from a silicon-containing monomer (b2), a polymerized unit from an α, β-ethylenically unsaturated aliphatic carboxylic acid (b3), from another aliphatic (meth) acrylic acid ester (b4) Polymerized units and aliphatic reactions It has a polymerization unit from the reactive emulsifier (b5) as a polymerization unit, does not contain an unsaturated bond other than a carbonyl group in the molecule, has a glass transition temperature of 0 to 70 ° C., and an acid value of 5 to 40 mgKOH / The surface treatment agent (P), which is an aqueous acrylic resin dispersion containing the acrylic resin (B) and the film-forming auxiliary (C), which are g, and having a minimum film-forming temperature of −5 to 40 ° C. X) It relates to a multi-layer surface-treated zinc-based plated steel sheet which is a resin layer obtained by drying after coating on.

[Wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a compound represented by the general formula (II)

(Wherein R3, R4 and R5 each independently represents a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 3 carbon atoms)

[Wherein R6, R7 and R8 are each independently substituted with a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group having 1 to 3 carbon atoms, or an alkoxyl group having 1 to 3 carbon atoms. Represents an alkoxyl group having 1 to 3 carbon atoms, and R9 represents the formula (IV)

Or general formula (V)

(Wherein R10 represents a hydrogen atom or a methyl group, and R11 represents an alkylene group having 1 to 12 carbon atoms).

  In the present invention, the surface treating agent (P) preferably contains a metal component (D) that is at least one selected from the group consisting of a zirconium compound (D1) and a metal oxide sol (D2). Here, the metal oxide sol (D2) is preferably at least one selected from the group consisting of silicon oxide sol, cerium oxide sol, yttrium oxide sol, neodymium oxide sol, and lanthanum oxide sol. It is preferable that the surface treatment agent (P) also contains a hydrolyzable silyl compound (E). The surface treatment agent (P) also contains a metal component (D) and a hydrolyzable silyl compound (E) which are at least one selected from the group consisting of a zirconium compound (D1) and a metal oxide sol (D2). The mass ratio of the total mass M of the metal contained in the metal component (D) and the total mass of the silicon mass Si1 contained in the component (E) and the silicon mass Si2 contained in the silicon-containing monomer (b2) [ M / (Si1 + Si2)] is preferably 0.1-50, and Si1 / Si2 is preferably 0.15-250. The film-forming aid (C) contained in the surface treatment agent (P) is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, methyl ethyl ketone, N- It is preferably at least one selected from the group consisting of methyl pyrrolidone and dipropylene glycol n-butyl ether.

In this invention, it is preferable that the ratio of the polymerization unit from (meth) acrylic acid ester (b1) is 0.1-50 mass parts with respect to 100 mass parts of acrylic resins (B).
In the present invention, the content of metal ions and / or atoms (A) in the base treatment layer (X) is preferably 0.5 to 100 mg / m ² .

  The multilayer surface-treated zinc-based plated steel sheet of the present invention solves the above-mentioned problems of the prior art, and is corrosion resistance, adhesion, antifouling property, film-forming property, ultraviolet resistance, alkali resistance, acid resistance and Excellent blackening resistance.

  The multi-layer surface-treated zinc-based plated steel sheet of the present invention is a two-layer surface treatment consisting of a base-treated layer (X) and an upper-layer treated layer (Y) covering the ground-treated layer (X) on at least one surface of the zinc-based plated steel sheet. It is necessary to have a layer.

The base treatment layer (X) contains metal ions and / or atoms (A) which are ions and / or atoms of at least one metal selected from the group consisting of Zr, Ti, Hf, Ce, La and Bi. There is a need to. The surface treatment layer (X) covers the defect part of the oxide film formed unevenly on the surface of the zinc-based plated steel sheet, and further covers the entire surface with a uniform film, thereby reacting the surface of the zinc-based plated steel sheet. And suppresses oxidation discoloration and corrosion due to micro battery formation on the steel sheet surface. Examples of the source of metal ions and / or atoms (A) include metals, oxides, hydroxides, fluorides, sulfates, carbonates, phosphates, nitrates, and other inorganic acid salts, organic acid salts, and the like. It is done. Among these, oxides, hydroxides and carbonates of Zr, Ti, Ce and La, and oxides, hydroxides and metals of Bi are particularly preferable.
In addition, when the term “metal ion and / or atom (A)” is added, a base treatment liquid used to form the base treatment layer (X), that is, treatment liquids (1) and (2) described later. In (3), at least one metal selected from the group consisting of Zr, Ti, Hf, Ce, La, and Bi exists as an ion, but exists as an ion in the base treatment layer (X). In some cases, it may exist as a covalently bonded atom, or in some cases, both of them coexist. The effect remains the same regardless of the form of the metal in the base treatment layer (X).

The content of metal ions and / or atoms in the ground processing layer (X) (A) is preferably from 0.5 to 100 mg / ^{m 2,} more preferably 1~38mg / ^{m 2,} 2~ More preferably, it is 31 mg / m ² . When the content of metal ions and / or atoms (A) is less than 0.5 mg / m ^{2, the} amount of metal ions and / or atoms (A) is too small, and the effect of the base treatment layer (X) is manifested. However, if it exceeds 100 mg / m ² , the ground treatment layer (X) becomes too thick and cohesive failure tends to occur in the treatment layer, and in this case, corrosion resistance and blackening resistance cannot be obtained.

  A method for forming the ground treatment layer (X) is not particularly limited, and examples thereof include coating (mode 1), self-deposition (mode 2), and electrolytic deposition (mode 3).

  Aspect 1 is a method in which a treatment liquid (1), which will be described later, for forming the base treatment layer (X) is brought into contact with the steel sheet surface, the treatment liquid adhesion amount on the steel sheet surface is adjusted, and drying is performed without washing. Hereinafter, although not specifically limited, the processing method which can be used is illustrated. Examples of the method for bringing the treatment liquid into contact with the steel sheet surface include roll coating, spray treatment, and immersion treatment. The time during which the treatment liquid is in contact with the steel sheet surface is not particularly limited. In addition, examples of the method for adjusting the treatment liquid adhesion amount on the steel sheet surface include a roll squeezing and an air knife, and examples of the drying method include a dryer, an oven, high-frequency heating, and infrared heating. The ultimate plate temperature at the time of drying is preferably 50 to 250 ° C, more preferably 70 to 150 ° C, and still more preferably 100 to 140 ° C. By adjusting the amount of adhesion and drying, the base treatment layer (X) of the present invention may contain metal ions and / or atoms (A) in a suitable range, and the drying temperature is not particularly limited.

  The treatment liquid (1) used in Embodiment 1 only needs to contain metal ions (A) that are ions of at least one metal selected from the group consisting of Zr, Ti, Hf, Ce, La, and Bi. Examples of the supply source of the metal ion (A) include carbonates, nitrates, sulfates, fluorides, chlorides, and other inorganic acid salts, organic acid salts, or organic chelate complexes. Among these, carbonates Organic acid salts and organic chelate complexes are preferred. These sources can be used alone or in combination. Zr and Ti are preferable as the metal in the metal ion (A). Examples of suitable sources of the metal ion (A) include basic zirconium carbonate, zirconium lactate, zirconium acetate, titanium lactate, titanium acetate, titanium acetylacetonate and the like. The treatment liquid (1) can contain a surfactant and a solvent component for improving wettability to the steel sheet surface. The treatment liquid (1) can also contain an additive component within a range that does not impair the effects of the present invention when imparting effects such as etching properties of the steel sheet surface. The pH of the treatment liquid (1) is not particularly limited, and may usually be about 2.0 to 13.0.

  Aspect 2 does not require an external treatment such as an electrolytic treatment, and a treatment liquid (2), which will be described later, that forms the base treatment layer (X) is brought into contact with the steel sheet surface to cause an autoprecipitation reaction, This is a method of forming a base treatment layer (X) through drying. Hereinafter, although it does not specifically limit, the processing method which can be used is illustrated. Examples of the method for bringing the treatment liquid (2) into contact with the steel sheet surface include roll coating, spray treatment, and immersion treatment. The time for which the treatment liquid is in contact with the steel sheet surface is preferably 0.5 to 5 seconds. If it is this range, the balance of sufficient autoprecipitation reaction and the etching reaction of a steel plate will become favorable. Examples of the water washing method include dipping and spraying, and the conditions and the like are particularly limited as long as the concentration of the metal ion (A) in the treatment liquid in contact with the steel plate surface after water washing is 10% or less before water washing. Not what you want. Examples of the drying method include a dryer, an oven, high-frequency heating, and infrared heating.

  The treatment liquid (2) used in the embodiment 2, which is one embodiment of the surface treatment agent (P) used in the present invention, is at least one metal selected from the group consisting of Zr, Ti, Hf, Ce, La and Bi. What is necessary is just to contain the metal ion (A) which is ion of this. The source of the metal ion (A) is not particularly limited, but the metal carbonate, nitrate, sulfate, fluoride, chloride and other inorganic acid salts, the metal ion (A) -containing fluoro acid and its Na Examples thereof include alkali metal salts such as salts and K salts, organic acid salts and organic chelate complexes of the metals. Of these, nitrates, fluorides, chlorides and fluoro acids are preferred. Specific sources include zirconium nitrate, zirconium hydrofluoric acid, titanium hydrofluoric acid, hafnium hydrofluoric acid, cerium chloride, nitric acid. Examples include cerium and lanthanum chloride. As the metal in the metal ion (A), Zr, Ti, Hf, Ce and La are preferable.

Aspect 3 is a method in which a treatment liquid (3), which will be described later, for forming the base treatment layer (X) is brought into contact with the surface of the steel sheet to cause an electrolytic reaction, followed by washing and drying to form the base treatment layer (X). It is. Hereinafter, although it does not specifically limit, the processing method which can be used is illustrated. The method of bringing the treatment liquid (3) into contact with the steel plate surface needs to be immersion. As electrolysis conditions, it is preferable to use stainless steel or a Pb-based alloy as the counter electrode (anode), set the temperature to room temperature to 40 ° C., and set the current density to 0.5 to 30 A / dm ² . The electrolysis time is set according to the required amount of metal atoms contained in the base treatment layer (X), but it is preferable that the film formed by this electrolysis usually contains ^{2 to} 50 mg / m ² of metal atoms. For example, the current density is 3 A / dm ²
In this case, about 0.5 to 3 seconds is appropriate. Examples of the water washing method include dipping, spraying, etc. The water washing conditions are particularly as long as the concentration of the metal ion (A) in the treatment liquid in contact with the steel plate surface after water washing is 10% or less before water washing. It is not limited. Examples of the drying method include a dryer, an oven, high-frequency heating, and infrared heating.

  The treatment liquid (3) used in the embodiment 3, which is one embodiment of the surface treatment agent (P) used in the present invention, is at least one metal selected from the group consisting of Zr, Ti, Hf, Ce, La and Bi. What is necessary is just to contain the metal ion (A) which is ion of this. The source of the metal ion (A) is not particularly limited, and the metal carbonate, nitrate, sulfate, fluoride, chloride and other inorganic acid salts, the metal ion (A) -containing fluoro acid and its Na Examples thereof include alkali metal salts such as salts and K salts, organic acid salts and organic chelate complexes of the metals. Of these, sulfates, fluorides, chlorides and fluoro acids are preferred, and specific sources include zirconium sulfate, zirconium hydrofluoric acid, titanium hydrofluoric acid, hafnium hydrofluoric acid, cerium chloride, Examples include cerium nitrate and lanthanum chloride. Zr, Ti, Ce and La are preferred as the metal in the metal ion (A).

  The amount of the metal ion (A) used is preferably 1 to 100 g / L in aspect 1, and 0.05 to 30 g / L in aspects 2 and 3.

  The treatment liquid (2) and the treatment liquid (3) further contain an acid component (F) that is at least one selected from the group consisting of hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid, and salts thereof. Is preferred. The acid component (F) is suitable for obtaining effects such as keeping the metal ion (A) in a dissolved state and increasing the conductivity of the treatment liquid. Examples of the salt include alkali metal salts (sodium salt, potassium salt, etc.), ammonium salts and the like. 0.1-50 g / L is suitable for the usage-amount of an acid component (F).

  The treatment liquid (2) and the treatment liquid (3) preferably also contain metal ions (G) that are ions of at least one metal selected from the group consisting of Mg, Al, Zn, Cu, and Ce. . The metal ion (G) promotes the autodeposition reaction. Nitrate, sulfate, carbonate and chloride are preferred as the source of metal ions (G). 0.1-10 g / L is suitable for the usage-amount of a metal ion (G).

When the metal ions (A) of the treatment liquid (2) and the treatment liquid (3) are supplied as fluorides, free fluorine ions in the treatment liquid (fluorine ions (F ⁻ ) having protons (H ⁺ ) as counter ions) ) The concentration is preferably 1 to 30 mg / L. Moreover, when containing metal ion (G), h / a which is ratio of mass concentration h of metal ion (G) and mass concentration a of metal ion (A) is 1-200, and pH is 2.0 or more, and it is preferable to satisfy pH ≦ −0.02 × h / a + 6.
When all these conditions are satisfied, a film excellent in corrosion resistance and adhesion to the substrate can be formed in a very short time. Free fluorine ions can be measured using a commercially available ion electrode.

  The free fluorine ion concentration can be adjusted to 1 to 30 mg / L by adjusting the mass concentration h of the metal ion (G). Moreover, pH of a process liquid (1), a process liquid (2), and a process liquid (3) can be adjusted with content of an acid component (F), and addition of an alkaline substance. The alkaline substance is not particularly limited, and any alkaline substance can be used as long as the pH can be adjusted without greatly degrading the performance of the surface treatment agent of the present invention. Preferred examples of such an alkaline substance include ammonia, sodium carbonate, organic amines (diethanolamine, triethylamine, etc.), alkali metal hydroxides (sodium hydroxide, potassium hydroxide, etc.) and the like.

  The upper treatment layer (Y) is a polymerization unit from the (meth) acrylic acid ester (b1) represented by the general formula (I), from the silicon-containing monomer (b2) represented by the general formula (III). Polymerized unit, polymerized unit from α, β-ethylenically unsaturated aliphatic carboxylic acid (b3), polymerized unit from other aliphatic (meth) acrylic acid ester (b4) and aliphatic reactive emulsifier (b5 ) Acrylic resin (B) having a polymerization unit as a polymerization unit, containing no aromatic ring in the molecule, a glass transition temperature of 0 to 70 ° C., and an acid value of 5 to 40 mgKOH / g and film formation Obtained by applying a surface treatment agent (P), which is an aqueous acrylic resin dispersion containing an auxiliary agent (C) and having a minimum film-forming temperature of −5 to 40 ° C., and then drying it on the base treatment layer (X). It is a resin layer. The “dispersion” referred to in the aqueous acrylic resin dispersion includes an emulsion and a suspension, and any of them may be used, but an emulsion is preferable.

  The glass transition temperature of the acrylic resin (B) needs to be 0 to 70 ° C., whereby the alkali resistance, acid resistance, workability and film transparency can be kept good. From the above viewpoint, the glass transition temperature is preferably 10 to 60 ° C, and more preferably 20 to 50 ° C. When the glass transition temperature is less than 0 ° C., not only the alkali resistance and acid resistance are remarkably lowered, but also the film hardness required during processing cannot be obtained. On the other hand, when it exceeds 70 ° C., the storage stability and the film followability required during processing are significantly reduced. The glass transition temperature can be measured using, for example, a dynamic viscoelasticity measuring apparatus (Rheograph Solid S manufactured by Toyo Seiki Seisakusho).

  The acrylic resin (B) does not have a carbon-carbon unsaturated bond and a carbon-nitrogen unsaturated bond in the molecule. When these unsaturated bonds are present, a radical reaction occurs due to ultraviolet rays, and a chromophore or an auxiliary chromophore is formed, so that the ultraviolet ray resistance is significantly lowered.

  The effect of polymerized units from (meth) acrylic acid ester (b1) on the upper layer treated layer (Y) and thus on the multilayer surface-treated zinc-coated steel sheet is that of alkali resistance, acid resistance and workability with increasing glass transition temperature. It is an improvement. Regarding the definitions of R3, R4 and R5 in the general formula (II), the alkyl group having 1 to 3 carbon atoms includes a methyl group, an ethyl group, a propyl group and an isopropyl group.

The (meth) acrylic acid ester (b1) is not particularly limited, and examples thereof include bornyl acrylate, isobornyl acrylate, bornyl methacrylate, and isobornyl methacrylate. Of the groups represented by formula (II), those in which R3, R4 and R5 are hydrogen atoms are bornyl groups, those in which R3 and R4 are hydrogen atoms and R5 is a methyl group are isobornyl groups. is there.

  The polymerized unit from the silicon-containing monomer (b2) enhances the adhesion between the acrylic resin (B) and the surface of the metal to be processed to improve workability, and improves alkali resistance and acid resistance. Regarding the definitions of R6, R7 and R8 in the general formula (III), the alkyl group having 1 to 3 carbon atoms includes methyl group, ethyl group, propyl group and isopropyl group, and the alkoxyl group having 1 to 3 carbon atoms is methoxyl. A C1-C3 alkoxyl group substituted with a C1-C3 alkoxyl group includes a methoxyethoxyl group and the like, including a group, an ethoxyl group, a propoxyl group and an isopropoxyl group. R11 in the general formula (V) is preferably an alkylene group having 1 to 6 carbon atoms, and more preferably an alkylene group having 1 to 4 carbon atoms. Regarding the definition of R11 in the general formula (V), examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a hexamethylene group, an octamethylene group, a decamethylene group, and a dodecamethylene group. It is done.

  The silicon-containing monomer (b2) is not particularly limited, but vinyltrimethoxysilane, vinyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxy Examples include propyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane.

  Polymerized units from the α, β-ethylenically unsaturated aliphatic carboxylic acid (b3) make the adhesion to the surface of the metal to be treated more firm and improve acid resistance and workability. The α, β-ethylenically unsaturated aliphatic carboxylic acid (b3) is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, and crotonic acid.

  Acrylic resin (B) comprises (meth) acrylic acid ester (b1), polymerized units from silicon-containing monomer (b2), polymerized units from α, β-ethylenically unsaturated carboxylic acid (b3), fat described below As the remaining structural units except for the polymerized units from the group-based reactive emulsifier (b5) as essential structural units, all of them contain no alkyl ring (meth) acrylate or cycloalkyl (meta ) And other aliphatic (meth) acrylate ester (b4) which is at least one (meth) acrylate ester selected from acrylate and hydroxyalkyl (meth) acrylate. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms. The cycloalkyl group preferably has 5 or 6 carbon atoms. Moreover, it is preferable that carbon number of the said hydroxyalkyl group is 2-6, and it is more preferable that it is 2-4.

  Specific examples of other aliphatic (meth) acrylic acid esters (b4) include methyl (meth) acrylate, ethyl acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and isobutyl (meth) ) Acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) ) Esters of (meth) acrylic acid such as acrylate and alkanols having 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms; Ets of (meth) acrylic acid such as cyclohexyl acrylate and cyclohexyl methacrylate and cycloalkanols having 5 or 6 carbon atoms. Ether; 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, etc. (meth) acrylic acid with 2 to 6 carbon atoms, and the like, particularly 2 to 4 esters of alkanediols.

  The polymer unit from the aliphatic reactive emulsifier (b5) contributes to the emulsion stability of the acrylic resin (B) in the surface treatment agent (P). The aliphatic reactive emulsifier (b5) is not particularly limited, but vinyl sulfonate, styrene sulfonate, sulfoethyl methacrylate, alkylallyl sulfosuccinate, alkenyl sulfosuccinate, α-sulfo- aliphatic reactive emulsifiers having sulfonic acid groups such as ω- (1- (alkoxy) methyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanediyl) salt, polyoxyalkylene alkenyl Aliphatic reactive emulsifiers having a sulfate group such as ether sulfate, polyoxyethylene alkylpropenyl phenyl ether sulfate, polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate, polyoxyalkylene alkenyl ether , Polyoxyethylene alkyl Examples include an aliphatic reactive emulsifier having an ether group such as lupropenyl phenyl ether and α- [1-{(allyloxy) methyl} -2- (nonylphenoxy) ethyl] -ω-hydroxypolyoxyethylene.

  Regarding the blending amount of the (meth) acrylic acid ester (b1), the proportion of the polymer unit from the (meth) acrylic acid ester (b1) is 0.1 to 50 parts by mass with respect to 100 parts by mass of the acrylic resin (B). It is preferable that it is 0.5-45 mass parts, and it is still more preferable that it is 3.0-35 mass parts. When the ratio is less than 0.1 parts by mass, the effect of adding the (meth) acrylic acid ester (A) is hardly exhibited, and when it exceeds 50 parts by mass, the storage stability is difficult to maintain.

  Regarding the compounding amount of the silicon-containing monomer (b2), the ratio of the polymer unit from the silicon-containing monomer (b2) is 0.5 to 2.0 parts by mass with respect to 100 parts by mass of the acrylic resin (B). Preferably, it is 0.7-2.0 mass parts, More preferably, it is 1.0-2.0 mass parts. When the ratio is less than 0.5 parts by mass, the effect of adding the silicon-containing monomer (b2) is hardly exhibited, and when it exceeds 2.0 parts by mass, the storage stability tends to decrease.

  Regarding the blending amount of the α, β-ethylenically unsaturated aliphatic carboxylic acid (b3), the acid of the acrylic resin (B) derived from the polymer unit from the α, β-ethylenically unsaturated aliphatic carboxylic acid (b3) The value is preferably 5 to 40 mgKOH / g, more preferably 10 to 35 mgKOH / g, and still more preferably 15 to 30 mgKOH / g. When the acid value is 5 to 40 mg KOH / g, adhesion (substrate adhesion and coating adhesion) and alkali resistance are improved. When the acid value is less than 5 mgKOH / g, the effect of adding the α, β-ethylenically unsaturated aliphatic carboxylic acid (b3) is hardly exhibited. Conversely, when it exceeds 40 mgKOH / g, the water-solubility of the acrylic resin (B) becomes strong, and not only the storage stability is lowered, but also the alkali resistance and acid resistance tend to be lowered. The acid value represents the number of mg of potassium hydroxide required per 1 g of the solid content of the acrylic resin to neutralize the carboxylic acid contained in the acrylic resin such as the acrylic resin (B).

  Regarding the blending amount of the aliphatic reactive emulsifier (b5), the proportion of the polymer unit from the aliphatic reactive emulsifier (b5) is 0.5 to 5 parts by mass with respect to 100 parts by mass of the acrylic resin (B). It is preferable that it is 1 to 3 parts by mass. When the ratio is less than 0.5 parts by mass, the storage stability of the surface treatment agent (P) is difficult to obtain, and when it exceeds 5 parts by mass, the water resistance tends to decrease.

  The production method of the acrylic resin (B) is not particularly limited, and for example, a conventionally known method such as a polymerization method in which a polymerization initiator, water, an emulsifier and a monomer are mixed at once; a monomer dropping method; a pre-emulsion method or the like is used. Can be manufactured. It is also possible to carry out multi-stage polymerization such as seed polymerization, core-shell polymerization, power feed polymerization, etc. to make the particles have a different phase structure. The polymerization temperature is usually 0 to 100 ° C., preferably 40 to 95 ° C., and the polymerization time is suitably 1 to 10 hours.

The polymerization initiator is not particularly limited. For example, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, t-butyl peroxybenzoate, lauroyl peroxide, t-butyl hydroperoxide and the like are conventionally known. A polymerization initiator can be used.
An acrylic resin (B) dispersion is obtained by the polymerization.

  Next, physical properties that the acrylic resin (B) should have are described. The glass transition temperature of the acrylic resin (B) needs to be 0 to 70 ° C, preferably 10 to 60 ° C, and more preferably 20 to 50 ° C. When the glass transition temperature is 0 to 70 ° C., durability against temperature change is improved, and excellent corrosion resistance and workability are exhibited. If the glass transition temperature is less than 0 ° C, not only the film hardness required at the time of processing cannot be obtained, but also the corrosion resistance tends to decrease. Tend to cause defect and cracking of the film.

  Regarding the glass transition temperature Tg of the acrylic resin (B), the glass transition temperature Tgi (i = 1, 2,..., I) and the mass fraction Xi (i = 1, 2,. Using i), a good approximate value of the glass transition temperature Tg can be calculated from the equation 1 / Tg = Σ (Xi / Tgi).

  The molecular weight of the acrylic resin (B) is preferably 10,000 to 200,000, more preferably 50,000 to 150,000, as a weight average molecular weight. When the molecular weight is 10,000 to 200,000, good storage stability and film-forming property can be obtained.

  A film-forming aid (C) is added to the acrylic resin (B) dispersion to prepare a surface treatment agent (P) as an aqueous acrylic resin dispersion. The surface treatment agent (P) needs to have an appropriate minimum film-forming temperature as an index indicating an appropriate film-forming property, and the film-forming aid (C) is for that purpose. The minimum film forming temperature of the surface treatment agent (P) needs to be −5 to 40 ° C., preferably 0 to 30 ° C., and more preferably 5 to 20 ° C. When the minimum film-forming temperature is within the range of -5 to 40 ° C, the corrosion resistance, alkali resistance, acid resistance and processability are improved, and the transparency of the film is increased. If the improved minimum film-forming temperature is less than −5 ° C., the storage stability of the surface treatment agent (P) tends to be not obtained, and if it exceeds 40 ° C., the film-forming property becomes insufficient, and the corrosion resistance, alkali resistance and acid resistance Tend to decrease. The minimum film-forming temperature of the acrylic resin (B) varies depending on the composition of the monomer forming the acrylic resin (B) and can be measured at the stage of the acrylic resin (B) dispersion. When blending C), the minimum film-forming temperature can be changed depending on the blending amount. That is, the minimum film-forming temperature can be lowered by increasing the blending amount of the film-forming auxiliary (C). The minimum film forming temperature of the acrylic resin (B) can be measured by a known method. In the present invention, a surface treatment agent (P) or a comparative surface treatment as a sample having a thickness of 0.2 mm on a stainless steel plate of a temperature gradient test device (minimum film-forming measuring device, manufactured by Sanyo Trading Co., Ltd.) After applying the agent, sealing, and drying, the temperature at the boundary between the uniform continuous film portion and the clouded portion was read to obtain the minimum film-forming temperature.

  Examples of the film-forming aid (C) include ethylene glycol, diethylene glycol, propylene glycol or dipropylene glycol alkyl ethers having 2 to 4 carbon atoms or alkanoic acid esters having 2 to 4 carbon atoms such as ethylene glycol monobutyl ether and diethylene glycol mono Examples include butyl ether acetate (common name: butyl carbitol acetate), dipropylene glycol n-butyl ether and the like; 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate; methyl ethyl ketone; N-methylpyrrolidone and the like. Among these, those having one ester bond and / or one or two ether bonds in the molecule, that is, an alkyl ether having 2 to 4 carbon atoms of ethylene glycol, diethylene glycol, propylene glycol or dipropylene glycol, or C2-C4 alkanoic acid ester and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate are preferable, and diethylene glycol monobutyl ether acetate and 2,2,4-trimethyl-1,3-pentanediol monoiso Isobutyrate is even more preferred. The film-forming auxiliary (C) lowers the minimum film-forming temperature by dissolving the surface of the dispersed particles and promoting fusion between the particles. However, the film-forming auxiliary (C) reduces ester bonds and / or ether bonds, particularly ester bonds and ether bonds. When it has, the effect | action improves.

  The blending amount of the film-forming auxiliary (C) is preferably 0.5 to 50 parts by mass, more preferably 2 to 45 parts by mass with respect to 100 parts by mass of the acrylic resin (B). It is still more preferable that it is -40 mass parts. When the blending amount is less than 0.5 parts by mass, the effect of adding the film-forming aid (C) is hardly exhibited, and as a result, it is difficult to obtain a good film-forming property, and the film has a good transparency. It becomes difficult to obtain the sex. Moreover, when it exceeds 50 mass parts, it will become the tendency for storage stability to fall. The term “film formation” refers to film formation, and microscopically refers to a state where particles of the acrylic resin (B) after drying are fused together. In the film-forming stage, the film-forming aid (C) acts as a film-forming aid for the acrylic resin (B) and promotes the fusion of the particles. As a result, irregular reflection of incident light is suppressed, the transparency of the film is increased, alkali resistance and acid resistance are improved, and workability is improved because the cohesive force of the film is improved.

  The upper treatment layer (Y) contains at least one metal component (D) selected from the group consisting of a zirconium compound (D1) and a metal oxide sol (D2) in addition to the acrylic resin (B) and the film-forming aid. It is preferable to contain.

  The zirconium compound (D1) is laminated in the film and suppresses oxygen permeability and water vapor permeability of the formed film and exhibits a very excellent barrier effect, thereby improving the corrosion resistance. Since zirconium has high durability against alkaline substances, the zirconium compound (D1) improves alkali resistance. Examples of the zirconium compound (D1) include zircon hydrofluoric acid, ammonium zircon fluoride, zirconium nitrate, zirconium acetate, zirconium oxide, zirconium hydroxide, ammonium zirconium carbonate, potassium zirconium carbonate, basic zirconium carbonate, zirconium stearate, zirconium octylate. Zirconium tetraacetylacetonate, zirconium tributoxy monoacetylacetonate, zirconium tetraacetylacetonate, zirconium tetranormal propoxy, zirconium tetranormal butoxy, zirconium tributoxy monostearate and the like.

  The metal oxide sol (D2) is laminated in the film and suppresses oxygen permeability and water vapor permeability of the formed film and exhibits a very excellent barrier effect, thereby improving the corrosion resistance. As the metal oxide sol (D2), magnesium oxide sol, aluminum oxide sol, silicon oxide sol, calcium oxide sol, scandium oxide sol, titanium oxide sol, vanadium oxide sol, manganese oxide sol, gallium oxide sol, germanium oxide sol, yttrium oxide sol Zirconium oxide sol, antimony oxide sol, lanthanum oxide sol, cerium oxide sol, neodymium oxide sol, hafnium oxide sol, and the like. Among these, silicon oxide sol and rare earth oxide sol, ie, scandium oxide sol, yttrium oxide sol, lanthanum oxide sol, cerium oxide sol and neodymium oxide sol are preferable because they have an ultraviolet blocking effect, and acrylic resin (B) by ultraviolet irradiation. UV degradation can be suppressed. Among these, silicon oxide sol, cerium oxide sol, yttrium oxide sol, and neodymium oxide sol, which are particularly excellent in the ultraviolet blocking effect, are more preferable.

  The upper treatment layer (Y) preferably further contains a hydrolyzable silyl compound (E). The hydrolyzable silyl compound (E) improves the corrosion resistance, alkali resistance and acid resistance in order to improve the adhesion between the formed film and the base material or the film and the top coat. In the present invention, the hydrolyzable silyl compound (E) refers to a compound represented by the following general formula (VI).

(In the formula, R12 represents a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, an isopropyl group or the like, or an alkyl group having 1 to 3 carbon atoms or a methoxyl group, an ethoxyl group, an isopropoxyl group or the like, or an alkoxyl group having 1 to 3 carbon atoms. R13 and R14 independently represent a hydrogen atom, a methyl group, an ethyl group, an isopropyl group or the like, and an alkyl group having 1 to 3 carbon atoms, and Y represents a hydroxyl group, an amino group, an N-aminoethylamino group, a glycidyloxy group. A linear or cyclic alkyl group having 1 to 6 carbon atoms substituted with a group or a mercapto group, or a vinyl group).

  Specific examples of the hydrolyzable silyl compound (E) include N- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycol. Sidoxypropylmethyldimethoxysilane, 2- (3,4 epoxy cyclohexyl) ethyltrimethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane and the like.

  Next, the use ratio between components in which the metal component (D) and the hydrolyzable silyl compound (E) are mainly involved will be described. Mass ratio of total mass M of metal contained in metal component (D), mass Si1 of silicon contained in hydrolyzable silyl compound (E) and mass of silicon Si2 contained in silicon-containing monomer (b2) [M / (Si1 + Si2)] is preferably from 0.1 to 50, more preferably from 1 to 20, and even more preferably from 2 to 10. When the mass ratio is in the range of 0.1 to 50, the corrosion resistance is improved. When the mass ratio is less than 0.1, improvement of the barrier effect and consequently improvement of corrosion resistance cannot be expected, and when it exceeds 50, the film forming property is deteriorated, and the film and the base treatment layer (X) or the film and the top coat are applied. The adhesion of the resin tends to decrease, and the corrosion resistance, alkali resistance and acid resistance tend to decrease.

  The mass ratio Si1 / Si2 of the silicon mass Si1 contained in the hydrolyzable silyl compound (E) and the silicon mass Si2 contained in the silicon-containing monomer (c2) is preferably 0.15 to 250, 3 to 100 is more preferable, and 0.5 to 50 is even more preferable. When the mass ratio is in the range of 0.15 to 250, the adhesion with the base treatment layer (X) is improved. When the mass ratio Si1 / Si2 is less than 0.15, it becomes difficult to obtain adhesion with the base treatment layer (X), and therefore, improvement in corrosion resistance cannot be expected. The storage stability of the agent tends not to be obtained.

  The blending amount of the acrylic resin (B) is preferably 40 to 98% by mass, more preferably 50 to 98% by mass with respect to the total solid content of the aqueous metal surface treatment agent of the present invention, and 70 to It is still more preferable that it is 98 mass%. When the blending amount is less than 40% by mass, good processability and top coating adhesion provided by the acrylic resin (B) cannot be obtained, and when it exceeds 98% by mass, the metal component (D) and hydrolyzability are not obtained. Even if the silyl compound (E) is blended, the blending effect cannot be obtained.

  The upper treatment layer (Y) is a resin other than the acrylic resin (B) for the purpose of improving chemical resistance and / or corrosion resistance, and is carbon-carbon unsaturated such as a carbon-carbon double bond. A bond can also contain what does not have carbon-nitrogen unsaturated bonds, such as a carbon-nitrogen double bond. Examples of such other resins include acrylic resins, epoxy resins, and urethane resins that do not have these unsaturated bonds. Other resins are not particularly limited, and those commonly used in aqueous metal surface treatment agents can be used. Examples of acrylic resins include poly (meth) acrylate methyl, poly (meth) acrylate butyl, Polyethyl acrylate 2-ethylhexyl, etc., epoxy resin, for example, hydrogenated bisphenol A type epoxy resin, etc., urethane resin, for example, aliphatic diisocyanate such as hexamethylene diisocyanate, isophorone diisocyanate and polyether polyol ( Polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.) or polyester polyols (condensates of adipic acid and ethylene glycol, such as hydroxyl groups at both terminals) can be used.

  The blending amount of the other resin is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and 50 parts by mass or less with respect to 100 parts by mass of the acrylic resin (B). In the case of an epoxy resin, it is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less; in the case of a urethane resin. Is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less. If each is used in excess of the preferred range, it becomes difficult to obtain the UV resistance, alkali resistance, acid resistance, processability and film permeability derived from the acrylic resin (B).

  The surface treatment agent (P) is a leveling agent for improving the coating property, a water-soluble solvent for improving the drying property of the film, a rust preventive pigment, a color pigment, and a lubrication, as long as the effects of the present invention are not impaired. Additives such as waxes that improve the properties can be included. As the leveling agent, a nonionic or cationic surfactant can be used, and examples thereof include polyethylene oxide or polypropylene oxide adduct of polyacetylene glycol and acetylene glycol compound, and water-soluble solvents include ethanol, isopropyl alcohol, t -Alcohols such as butyl alcohol and propylene glycol, esters such as ethyl acetate and butyl acetate, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone.

  About the manufacturing method of a surface treating agent (P), if it is a method which can manufacture a surface treating agent (P) stably, it will not restrict | limit in particular. The treatment agent of the present invention generally comprises a dispersion of acrylic resin (B) obtained by the above polymerization, a film-forming aid (C), and optionally a metal component (D), hydrolysis. It can manufacture by adding a stirring silyl compound (E) and / or other arbitrary components, and stirring.

  The solid content concentration of the surface treatment agent (P) is not particularly limited, but is preferably 3 to 50% by mass, and more preferably 5 to 35% by mass. If the solid content concentration is less than 3% by mass, there may be a problem in applicability, and the cost of the treatment agent increases. If it exceeds 50% by mass, the storage stability of the surface treatment agent (P) tends to decrease.

The surface treatment agent (P) is applied on the base treatment layer (X) applied on the galvanized steel sheet, preferably 50 to 250 ° C., more preferably 70 to 150 ° C., and still more preferably 100 to The upper treatment layer (Y) is formed by drying at an ultimate temperature of 140 ° C. (an ultimate metal material temperature). If the ultimate temperature is less than 50 ° C., the solvent of the surface treatment agent (P) does not completely evaporate, and if it is higher than 250 ° C., there is a possibility that a part of the film formed by the surface treatment agent (P) is decomposed. is there. Preferably the coating weight after drying is 0.05-5 g / ^{m 2,} more preferably from 0.2 to 3 g / ^{m 2,} and more to be 0.5 to 2.5 g / ^{m 2} Even more preferred. When coating mass is less than 0.05 g / m ^2, can not sufficiently cover the surface of the metal material, it is impossible to express the performance, larger than 5 g / m ^2, dregs generated during machining, The operability is reduced.

  The zinc-based plated steel sheet to which the multilayer surface treatment of the present invention is applied is not particularly limited, and is galvanized steel sheet, zinc-nickel plated steel sheet, zinc-iron plated steel sheet, zinc-chromium plated steel sheet, zinc-aluminum plated steel sheet, zinc -Titanium-plated steel sheet, zinc-magnesium-plated steel sheet, zinc-manganese-plated steel sheet, zinc-aluminum-magnesium-plated steel sheet, zinc-aluminum-magnesium-silicon-plated steel sheet, etc. Cobalt, molybdenum, tungsten, nickel, titanium, chromium, aluminum, manganese, iron, magnesium, lead, bismuth, antimony, tin, copper, cadmium , Arsenic, etc. The layer of silica, alumina, it may also be used those obtained by dispersing inorganic substances titania. Furthermore, the present invention can also be applied to a multilayered zinc-based plated steel sheet in combination with the above-described zinc-based plating and other types of plating such as iron plating, iron-phosphorus plating, nickel plating, cobalt plating and the like. The plating method is not particularly limited, and any known method such as an electroplating method, a hot dipping method, a vapor deposition plating method, a dispersion plating method, or a vacuum plating method can be used.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto. Preparation of the test plate, examples and comparative examples, and a method for applying the surface treatment agent will be described.

[Undercoat layer (X)]
Table 1 shows the processing conditions and components of the ground treatment layer (X).

[Upper layer (Y)]
(Meth) acrylic acid ester (b1), silicon-containing monomer (b2), α, β-ethylenically unsaturated fat used for surface treatment agent (P) and surface treatment agent for upper layer treatment which is a surface treatment agent for comparison Table 2 shows the aliphatic carboxylic acid (b3), other aliphatic (meth) acrylic acid ester (b4), and a comparative monomer. As the aliphatic reactive emulsifier (b5), Eleminol JS-2 (manufactured by Sanyo Chemical Industries, alkylallylsulfosuccinate) was used. Table 3 shows the used amount (parts by mass) of each monomer and the physical properties of the resulting acrylic resin when the total used amount of these monomers is 100 parts by mass. In addition, the usage-amount of the aliphatic reactive emulsifier (b5) was 0.5 mass part in all the surface treatment agents for upper-layer processes.

Production Example of Acrylic Resin (B) Dispersion After replacing the internal air with nitrogen gas in a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, 120 parts by mass of ion-exchanged water and Eleminol JS- 2 0.5 parts by mass was added to make an aqueous solution. To the dropping funnel, 10.0 parts by weight of isobornyl methacrylate, 52.0 parts by weight of methyl methacrylate, 16.0 parts by weight of 2-ethylhexyl acrylate, 18.0 parts by weight of n-butyl methacrylate, 1.0 of vinyltri (methoxyethoxy) silane Part by mass and 2.5 parts by mass of methacrylic acid were added and mixed to obtain a mixed monomer. Next, after the temperature of the aqueous solution was raised to 70 ° C., 10% by mass of the mixed monomer was charged into the flask, and then 0.3 part by mass of ammonium persulfate was charged. After the completion of the polymerization reaction, the remaining 90% by mass of the mixed monomer was added dropwise over 3 hours. After completion of dropping, the mixture temperature was raised to 75 ° C. and maintained for 1 hour. After cooling to 40 ° C., the pH was adjusted to 7 with aqueous ammonia. The acrylic resin obtained in this production example is the acrylic resin (B2) in Table 3.
Similarly, acrylic resin (B1) and acrylic resins (B3) to (B13) were produced. Among these, acrylic resins (B1) to (B8) satisfy the essential requirements of the present invention, but acrylic resins (B9) to (B13) lack at least one of the essential requirements of the present invention.

  Tables 4 and 5 show the components of the surface treatment agent (P) (Y1 to Y44) and the comparative surface treatment agents (Y45 to Y52).

Preparation method of surface treating agent of Examples Y1-Y2 and Y39-44 and Comparative Examples Y45-Y50 and Y52 At room temperature, an acrylic resin (B) dispersion and a film-forming aid (C) are represented in distilled water. 4 and the ratio shown in Table 5 were added to prepare a surface treatment agent. The solid concentration of the surface treatment agent was 10% by mass.

Preparation Method of Surface Treatment Agents of Examples Y3 to Y37 and Comparative Example Y51 Zirconium compound (D1), metal oxide sol (D2), hydrolyzable silyl compound (E), and acrylic resin in distilled water at room temperature A surface treatment agent was prepared by adding the dispersion of (B) and the film-forming aid (C) in the proportions shown in Tables 4 and 5. The solid concentration of the surface treatment agent was 10% by mass.

Preparation Method of Surface Treatment Agent of Example Y38 In the surface treatment agent Y2 of Table 4, 30% by mass in the solid content ratio of the acrylic resin (B) was changed to a polyester polyol type urethane resin. Polyester polyol type urethane resin is 170 parts by mass of polyester polyol obtained from tetramethylene glycol and adipic acid, 30 parts by mass of 1,6-hexamethylene diisocyanate, 25 parts by mass of 2,2-dimethylolpropionic acid and N-methyl-2. An aqueous solution having a glass transition temperature of 100 ° C. and a minimum film-forming temperature of 0 ° C. or less obtained by dispersing a prepolymer obtained by reacting 100 parts by mass of pyrrolidone in deionized water using triethylamine It is a urethane resin.

Test materials are listed below. The plate thickness was all 0.8 mm.
GI hot dip galvanized steel sheet basis weight = 60/60 g / m ²
EG Electrogalvanized steel sheet basis weight = 25 / 25g / m ²
GL Hot-dip zinc-55% aluminum alloy plated steel sheet Weight per unit area = 120/120 g / m ²

The surface treatment process is described below.
(1) Degreasing process Fine cleaner 4336 (registered trademark: manufactured by Nihon Parkerizing Co., Ltd.), which is a silicate-based alkaline degreasing agent, is dissolved in water at a concentration of 20 g / L. Sprayed for 2 minutes, washed with pure water for 30 seconds and dried.
(2) Substrate treatment One of the surface treatment liquids as an example shown in Table 1 is subjected to a surface treatment so that a predetermined film amount is obtained on a material after degreasing treatment by a predetermined method, and a maximum reached plate temperature of 80 Dried at ℃.
(3) Upper layer treatment One of the surface treatment liquids (Y1 to Y44) as examples and the surface treatment liquids (Y45 to Y52) as comparative examples shown in Tables 4 and 5 is used as a test material after the base treatment. The coating was applied by coating so that the coating amount after drying was 1.5 g / m ² and dried at a maximum reached plate temperature of 80 ° C. to obtain a test plate.

[Evaluation method]
(1) Corrosion resistance According to JASO M609, a combined cycle test in which salt spray (35 ± 2 ° C. for 2 hours), drying (60 ± 1 ° C. for 4 hours), and wetness (50 ± 1 ° C. for 2 hours) is one cycle. This was confirmed by confirming the occurrence of white rust in the unprocessed part, the cross cut part and the end face part in 168 cycles.
<Evaluation criteria>
Unprocessed part: The area where white rust was generated in the unprocessed part was visually evaluated.
◎: No white rust occurrence ○: White rust occurrence area ratio is 10% or less of the total area Δ: White rust occurrence area ratio is more than 10% of the total area, 30% or less ×: White rust occurrence area ratio is 30 of the total area % Super cross cut part: The surface of the surface-treated steel sheet was cross cut with a cutter, and the width of white rust generated from the cross cut part was measured.
◎: White rust width is 2 mm or less ○: White rust width is more than 2 mm, 5 mm or less Δ: White rust width is more than 5 mm, 8 mm or less ×: White rust width is more than 8 mm End face part: The edge part of the surface-treated steel sheet is cut off, The width of white rust generated from the part where the metal material was exposed was measured.
◎: White rust width 5 mm or less ○: White rust width 5 mm or more, 10 mm or less Δ: White rust width 10 mm or more, 15 mm or less ×: White rust width 15 mm or less

(2) Top coat adhesion (top coat adhesion)
A melamine alkyd resin paint was applied to the surface-treated steel sheet using a bar coater so that the dry film thickness was 25 μm, and baked at a furnace temperature of 130 ° C. for 20 minutes. Next, a grid of 1 mm and 100 squares was applied with a cutter, and the part was further subjected to Erichsen processing by extruding 7 mm. A tape peeling test was performed on the processed part, and the remaining number of melamine alkyd resin layers was evaluated.
<Evaluation criteria>
◎: 100 ◯: 98 or more and less than 100 △: 50 or more and less than 98 ×: less than 50

(3) Base material adhesion The surface-treated steel sheet was subjected to an Erichsen process by extrusion of 7 mm, and a tape peeling test of the processed part was performed. The peeled state was evaluated visually. Note that peeling includes both peeling of the base treatment layer and peeling of the upper treatment layer.
<Evaluation criteria>
◎: No peeling ○: Peeling area is over 1%, 20% or less △: Peeling area is over 20%, 50% or less ×: Peeling area is over 50%

(4) Antifouling property A 10% by mass black pigment dispersion was sprayed onto the surface-treated steel sheet by spraying, washed with water, and the antifouling property was evaluated by color tone change (ΔE) before and after the test. The color change was measured using Color Meter ZE2000 (manufactured by NIPPON DENSHOKU, light source: halogen lamp 12V / 2A). The same applies to the changes in color tone of the following UV resistance, alkali resistance and acid resistance.
<Evaluation criteria>
A: ΔE ≦ 1
○: 1 <ΔE ≦ 3
Δ: 3 <ΔE ≦ 5
×: 5 <ΔE

(5) Film-forming property The surface state of the surface-treated steel sheet was evaluated by observing with an atomic force microscope (AFM).
<Criteria>
A: A uniform film without irregularities was observed. B: A uniform film with few irregularities was observed. Δ: A film with irregularities was observed. X: A film with clear confirmation of polymer particles was observed.

(6) Ultraviolet resistance The surface-treated steel sheet was irradiated with 365-nm ultraviolet light for 4 hours with a fluorescent ultraviolet light wetting device (UVCON fluorescent lamp ultraviolet light wet exposure tester), and then at an atmospheric temperature of 50 ° C. and a humidity of 60% Rh for 2 hours. 196 cycles were performed with the condition of standing as one cycle, and the change in color tone (ΔE) before and after the test was evaluated.
<Evaluation criteria>
A: ΔE ≦ 1
○: 1 <ΔE ≦ 3
Δ: 3 <ΔE ≦ 5
×: 5 <ΔE

(7) Alkali resistance The surface-treated steel sheet was immersed in a 3 mass% sodium hydroxide aqueous solution at 25 ° C for 10 minutes, and the color tone change (ΔE) before and after the test was evaluated.
<Evaluation criteria>
A: ΔE ≦ 1
○: 1 <ΔE ≦ 3
Δ: 3 <ΔE ≦ 5
×: 5 <ΔE

(8) Acid resistance The surface-treated steel sheet was immersed in 3 mass% sulfuric acid at 25 ° C. for 3 hours, and the color tone change (ΔE) before and after the test was evaluated.
<Evaluation criteria>
A: ΔE ≦ 1
○: 1 <ΔE ≦ 3
Δ: 3 <ΔE ≦ 5
×: 5 <ΔE

(9) Blackening resistance The surface-treated steel sheet was allowed to stand at an ambient temperature of 70 ° C. and a humidity of 95% Rh for 120 hours, and the change in brightness (ΔL) before and after the test was evaluated.
<Evaluation criteria>
A: ΔL ≦ 2
○: 2 <ΔE ≦ 5
Δ: 5 <ΔE ≦ 10
×: 10 <ΔE

Tables 6 to 9 show the evaluation results. From Table 6 to Table 9, the multilayer surface-treated zinc-based plated steel sheet of the present invention was excellent in corrosion resistance, adhesion, antifouling property, film forming property, ultraviolet resistance, alkali resistance, acid resistance and blackening resistance.
On the other hand, Comparative Example 1 and Comparative Example 2 having no base treatment layer were inferior in blackening resistance, alkali resistance and acid resistance, and inferior in corrosion resistance. Further, Comparative Example 3 in which the minimum film-forming temperature (MFT) of the acrylic resin (B) of the upper treatment layer exceeds the specified range is inferior in film-forming property, and as a result, most of the film performance is not fully exhibited, and conversely specified. The comparative example 4 which is less than the range was inferior in adhesiveness with a coating material and a base material, and also inferior in ultraviolet-ray resistance. Further, Comparative Example 5 containing no (meth) acrylic acid ester (b1) unit which is an essential polymerization unit of the acrylic resin (B) forming the upper layer of the multilayer surface-treated zinc-based plated steel sheet of the present invention is corrosion resistance and alkali resistance. In addition, the acid resistance was remarkably inferior, and the blackening resistance was also inferior. Comparative Example 6 containing no silicon-containing monomer (b2) unit was inferior in most performances such as corrosion resistance, alkali resistance, acid resistance and blackening resistance. Moreover, the comparative example 7 which contains the styrene unit which should not be contained in the acrylic resin (B) which forms the upper layer of the multilayer surface treatment zinc-plated steel plate of this invention as a polymerization unit was inferior in ultraviolet-ray resistance. The comparative example 8 which does not contain a (meth) acrylic acid ester (b1) unit but contains a styrene unit as a polymerization unit is inferior in UV resistance and blackening resistance, and this tendency was obtained by adding a zirconium compound to the comparative example 8. The same was true for Comparative Example 9. In addition, Comparative Example 10 containing an adamantane acrylate unit in place of the (meth) acrylic ester (b1) unit has a poor film formation due to its bulkiness, and as a result, corrosion resistance, alkali resistance and acid resistance have begun. Many properties were inferior.

  As is clear when Examples 7 to 15 are compared, as M / (Si1 + Si2) increases, the non-processed portion corrosion resistance, alkali resistance, acid resistance and blackening resistance tend to improve. From Example 15, it can be seen that when M / (Si1 + Si2) exceeds the preferred range, the substrate adhesion and the topcoat adhesion tend to be slightly inferior. This is presumed to be because the film becomes hard and cracking tends to occur. Conversely, from Example 7, it can be seen that if M / (Si1 + Si2) is less than the preferred range, the corrosion resistance and alkali resistance tend to be slightly inferior. This is presumed to be because the degree of crosslinking of the film is not sufficient. Examples 10 to 12 in which M / (Si1 + Si2) is in the most preferable range are most preferable in comparison with Examples 8 to 9 in which M / (Si1 + Si2) is less than the most preferable range because of excellent non-processed portion corrosion resistance, alkali resistance, and blackening resistance. Compared with Examples 13 to 14 exceeding the range, the top coating adhesion, the substrate adhesion and the alkali resistance are excellent, and M / (Si1 + Si2) is the most preferable range, and the corrosion resistance, blackening resistance, alkali resistance, top coating It turns out that the film | membrane which is extremely excellent in adhesiveness, base-material adhesiveness, etc. can be formed.

  Next, as is clear when Examples 26 to 33 are compared, there was a tendency that the non-processed portion corrosion resistance and alkali resistance improved as Si1 / Si2 increased. As is clear from Example 33, when Si1 / Si2 exceeds the preferred range, the cut portion corrosion resistance, end surface portion corrosion resistance, topcoat adhesion, substrate adhesion, antifouling property, film-forming property, and ultraviolet resistance are slightly reduced. Tend to. As is clear from Example 26, when Si1 / Si2 is less than the preferred range, the top coat adhesion, substrate adhesion, antifouling property, film-forming property, and ultraviolet resistance tend to decrease. In Examples 29 to 30 in which Si1 / Si2 is in the most preferable range, an improvement tendency of ultraviolet resistance was recognized as compared with Examples 31 to 32 exceeding the most preferable range, and Example 27 which is less than the most preferable range. Compared to ˜28, it is excellent in antifouling property and ultraviolet resistance. Therefore, when Si1 / Si2 is in the most preferable range, it can be seen that a very good film excellent in all of corrosion resistance, topcoat adhesion, substrate adhesion, antifouling property, film forming property and ultraviolet resistance can be formed. This is presumably because, when Si1 / Si2 is in the optimum range, a film having an excellent balance between the adhesion with the base material and the top coat and the self-crosslinking property of the upper layer treatment layer (Y) itself is formed. . As a result, it is presumed that since there is no unnecessary functional group, the antifouling property is excellent, and the degree of crosslinking of the film is increased, so that the UV resistance is also excellent.

Next, the relationship between M / (Si1 + Si2) and Si1 / Si2 will be described. Examples 27 to 32 in which both M / (Si1 + Si2) and Si1 / Si2 are in a preferable range are the non-processed part, the cut part and the end face part corrosion resistance, the coating and base material adhesion, the film forming property, the alkali resistance, the acid resistance and It is extremely excellent in blackening resistance and excellent in antifouling properties and UV resistance.
When discussed in comparison with other examples, Examples 27 to 32 are unprocessed parts, cut parts and end face parts as compared with Example 18 in which both M / (Si1 + Si2) and Si1 / Si2 are less than the preferred range. Excellent in corrosion resistance, substrate adhesion, alkali resistance, acid resistance and blackening resistance, and M / (Si1 + Si2) and Si1 / Si2 both exceed the preferred range Cut portion and end face portion corrosion resistance, Compared with Example 25 which is excellent in top coating and substrate adhesion, film-forming property, alkali resistance, acid resistance and blackening resistance, and M / (Si1 + Si2) is less than the preferred range and Si1 / Si2 is more than the preferred range. Excellent in cut and end face corrosion resistance, topcoat and substrate adhesion, film-forming properties, acid resistance and blackening resistance, M / (Si1 + Si2) exceeds the preferred range Topcoat and substrate adhesion as compared with Example 34 in which Si1 / Si2 is less than the preferred range, film formability, alkali resistance, superior in acid resistance and blackening.

  In Examples 27 to 32 in which both M / (Si1 + Si2) and Si1 / Si2 are in the preferred range, one of M / (Si1 + Si2) and Si1 / Si2 satisfies the preferred range, but the other does not. Even better results. For example, in Examples 27 to 32, Si1 / Si2 satisfies the preferred range, but M / (Si1 + Si2) does not satisfy the preferred range. Compared to Examples 19 to 24, the unprocessed part, the cut part, and the end face part corrosion resistance, Excellent in substrate adhesion and blackening resistance.

Claims (8)

It is a multilayer surface-treated zinc-based plated steel sheet having two surface treatment layers consisting of a ground-treated layer (X) and an upper-layer treated layer (Y) covering the ground-treated layer (X) on at least one surface of the zinc-based plated steel sheet. The base treatment layer (X) contains at least one metal ion and / or atom (A) selected from the group consisting of Zr, Ti, Hf, Ce, La and Bi. An inorganic coating layer, wherein the upper treatment layer (Y) is a polymerization unit from isobornyl (meth) acrylate (b1), a polymerization unit from a silicon-containing monomer (b2) represented by the following general formula (III), α, Polymerized unit from β-ethylenically unsaturated aliphatic carboxylic acid (b3), polymerized unit from other aliphatic (meth) acrylic acid ester (b4) and polymerized unit from aliphatic reactive emulsifier (b5) Polymerize The other aliphatic (meth) acrylic acid ester (b4) is (meth) acrylic acid and an alkanol having 1 to 10 carbon atoms, a cycloalkanol having 5 or 6 carbon atoms, or an alkane having 2 to 6 carbon atoms. Aliphatic reactive emulsifier (b5) is a vinyl sulfonate, sulfoethyl methacrylate salt, alkylallyl sulfosuccinate, alkenyl sulfosuccinate, α-sulfo-ω- (1- (alkoxy) Methyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanediyl) salt, polyoxyalkylene alkenyl ether sulfate, polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate ester salt or A polyoxyalkylene alkenyl ether with a carbonyl group Contains acrylic resin (B) and film-forming aid (C) having no external unsaturated bond, glass transition temperature of 0 to 70 ° C., and acid value of 5 to 40 mg KOH / g, A multilayer surface-treated zinc-based resin layer, which is a resin layer obtained by applying a surface treatment agent (P), which is a water-based acrylic resin dispersion having a film forming temperature of -5 to 40 ° C., to a base treatment layer (X) and then drying it. Plated steel:
[Wherein R6, R7 and R8 are each independently substituted with a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group having 1 to 3 carbon atoms, or an alkoxyl group having 1 to 3 carbon atoms. Represents an alkoxyl group having 1 to 3 carbon atoms, and R9 represents the formula (IV)
Or general formula (V)
(Wherein R10 represents a hydrogen atom or a methyl group, and R11 represents an alkylene group having 1 to 12 carbon atoms).   The multilayer surface-treated zinc system according to claim 1, wherein the surface treatment agent (P) contains a metal component (D) which is at least one selected from the group consisting of a zirconium compound (D1) and a metal oxide sol (D2). Plated steel sheet. The multilayer surface-treated zinc-based plated steel sheet according to claim 1 or 2, wherein the surface treatment agent (P) contains a hydrolyzable silyl compound (E). The surface treatment agent (P) contains at least one metal component (D) selected from the group consisting of a zirconium compound (D1) and a metal oxide sol (D2) and a hydrolyzable silyl compound (E), and a metal Mass ratio of total mass M of metal contained in component (D) to total mass of silicon mass Si1 contained in hydrolyzable silyl compound (E) and silicon mass Si2 contained in silicon-containing monomer (b2) The multi-layer surface-treated galvanized steel sheet according to claim 1, wherein [M / (Si1 + Si2)] is 0.1 to 10 , and Si1 / Si2 is 0.15 to 250. Multilayer surface-treated zinc system according to any one of claims 1-4 content of the underlying process layer metal ions and / or atoms in the (X) (A) is 0.5 to 100 mg / ^{m 2} Plated steel sheet. Ratio of polymerized units from isobornyl (meth) acrylate (b1) is, relative to the acrylic resin (B) 100 parts by weight, according to any one of claims 1-5 which is 0.1 to 50 parts by weight Multi-layer surface-treated galvanized steel sheet. The multi-layer surface-treated zinc system according to claim 2 or 4 , wherein the metal oxide sol (D2) is at least one selected from the group consisting of silicon oxide sol, cerium oxide sol, yttrium oxide sol, neodymium oxide sol, and lanthanum oxide sol. Plated steel sheet. Film-forming aid (C) is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, methyl ethyl ketone, N-methylpyrrolidone and dipropylene glycol n-butyl ether The multilayer surface-treated zinc-based plated steel sheet according to any one of claims 1 to 7, which is at least one selected from the group consisting of: