JP4457821B2 - High corrosion resistance surface-treated steel sheet and method for producing the same - Google Patents

Description

  The present invention relates to a highly corrosion-resistant surface-treated steel sheet that is particularly suitable for automobile inner and outer plates, and relates to an environment-adaptive surface-treated steel sheet that does not contain chromium at all during its production and in its surface-treated film, and a method for producing the same.

  Conventionally, steel sheets for home appliances, steel sheets for building materials, and steel sheets for automobiles have been used for the purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of galvanized steel sheets or aluminum galvanized steel sheets. Steel plates subjected to chromate treatment with a treatment liquid containing chromic acid or a salt thereof as a main component are widely used. This chromate treatment is an economical treatment method that has excellent corrosion resistance and can be performed relatively easily.

  Chromate treatment uses hexavalent chromium, a pollution-controlling substance, but this hexavalent chromium is treated in a closed system in the treatment process, completely reduced and recovered, and not released into nature. Since the elution of chromium from the chromate film can be made almost zero by the sealing action of the organic film, the environment and the human body are not substantially contaminated by hexavalent chromium. However, due to recent global environmental problems, there is a growing trend to voluntarily reduce the use of heavy metals including hexavalent chromium. In addition, in order not to pollute the environment when the shredder dust of discarded products is dumped, there has been a movement to minimize or reduce the amount of heavy metals contained in the product.

  For this reason, in order to prevent the occurrence of white rust in galvanized steel sheets, many treatment techniques that do not rely on chromate treatment, so-called chromium-free techniques, have been proposed. For example, there is a method of forming a thin film by a method such as immersion, coating, or electrolytic treatment using an inorganic compound, an organic compound, an organic polymer material, or a solution combining these.

Specifically, the following methods can be listed as conventional techniques.
(1) A method of forming a film by immersing or applying a treatment liquid in a treatment liquid containing a polyhydric phenol carboxylic acid such as tannic acid and a silane coupling agent (for example, Patent Document 1, Patent Document 2, etc.)
(2) A method of forming a film using a treatment liquid in which a polyhydric phenol carboxylic acid such as tannic acid or a phosphoric acid compound is blended with an organic resin (for example, Patent Document 3 to Patent Document 6)
(3) A method of applying a film containing an organic resin and a silane coupling agent (for example, Patent Document 7 to Patent Document 13)

JP 7-216268 A Japanese Patent No. 2968959 JP-A-8-325760 JP 2000-34578 A JP 2000-199076 A JP 2000-248380 A JP-A-11-106945 JP 2000-319787 A JP 2000-248384 A Japanese Patent Laid-Open No. 2000-177871 JP 2000-199076 A JP 2000-281946 A Japanese Patent Laid-Open No. 2000-14443

As the method of (1), there is a method of treating with an aqueous solution in which a polyhydric phenol carboxylic acid and a silane coupling agent, and further metal ions are blended. . However, although this treatment method can provide good adhesion, it has a drawback that sufficient corrosion resistance cannot be obtained.
As the above method (2), for example, Patent Document 3 discloses a method in which treatment is performed with a treatment liquid in which polyhydric phenolcarboxylic acid, an organic resin, and metal ions are blended. Patent Document 4 discloses a method of immersing in a treatment liquid to which an organic resin and a phosphoric acid compound are added or applying a treatment liquid and then drying. However, although the protective film formed by these treatment liquids contributes to the improvement of the corrosion resistance to some extent, the high degree of corrosion resistance as in the case of the chromate treatment cannot be obtained.

As the method (3), for example, Patent Document 8 and Patent Document 9 disclose one having a film containing an organic resin and a silane coupling agent, and further a thiocarbonyl compound, a phosphate compound, and a vanadium compound. However, the corrosion resistance is not sufficient because the organic resin is polyurethane or acrylic olefin resin. Patent Document 11 has a film made of an acid-modified epoxy resin. Patent Document 10 discloses a resin containing a hydroxyl group / carboxyl group / glycidyl group / phosphate group-containing monomer as a copolymerization component. Although the thing which has the film | membrane which mix | blended the phosphoric acid compound is disclosed, respectively, corrosion resistance is not enough also about these. Patent Document 7 discloses a film having a film in which a polyvinylphenol derivative, a silane coupling agent, and an etching agent such as phosphoric acid are blended. However, sufficient corrosion resistance cannot be obtained. Patent Document 12 discloses a film having an organic resin blended with an etching agent, while Patent Document 13 discloses a film having a film blended with an organic resin and a silane coupling agent. There is no description and the corrosion resistance is insufficient.
Accordingly, an object of the present invention is to provide a surface-treated steel sheet that solves such problems of the prior art and does not contain chromium in the film and that provides excellent corrosion resistance.

Hereinafter, the knowledge by the present inventors and the anticorrosion mechanism aimed by the present invention based on this knowledge will be described.
It is considered that the corrosion of the galvanized steel sheet with the surface treatment film proceeds in the following process.
(1) Corrosion factors (oxygen, water, chlorine ions, etc.) permeate into the surface treatment film and diffuse to the plating film / surface treatment film interface.
(2) Zinc dissolves by the following oxidation-reduction reaction at the plating film / surface treatment film interface.
Cathode reaction: 2H ₂ O + O ₂ + 4e ⁻ → 4OH ⁻
Anode reaction: 2Zn → 2Zn ²⁺ + 4e ⁻

Therefore, to improve the corrosion resistance of the galvanized steel sheet, it is essential to suppress the progress of both reactions (1) and (2).
(a) Advanced barrier layer that acts as a diffusion barrier for corrosion factors (mainly suppresses the cathode reaction)
(b) Reaction layer with plating metal that inactivates the plating film surface layer (mainly acts to suppress the anode reaction)
It is most effective to have a film configuration that has a self-repairing action when a defect occurs in the reaction layer.

  As a result of the study, such a film configuration is not a two-layer film formed by separately coating a barrier layer forming component and a reaction layer forming component as in the prior art, but a single layer formed by a single coating. Realizing in the film, specifically, forming the barrier layer (a) above the film and the reaction layer (b) above the film, more preferably self-repairing action in the film. It has been found that the effect of improving the corrosion resistance can be obtained by synergistic effects by precipitating the substance to be generated. When such a single-layer coating is defined as a pseudo-two-layer coating, the barrier layer and the reaction layer constituting the pseudo-two-layer coating are between the two-layer coating formed by the conventional double coating. There is no clear interface. On the contrary, it is considered that a high degree of corrosion resistance improvement effect that cannot be obtained by the conventional single layer coating can be exhibited by making the both compositions in a gradient composition.

The pseudo two-layer film as described above is prepared by reacting a water-dispersible liquid of a resin obtained by reacting a specific modified epoxy resin with a hydrazine derivative having active hydrogen, and a silane coupling agent and a specific acid component (phosphoric acid). The surface treatment composition containing a phosphoric acid compound) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and dried.
A silane coupling agent is known to have an effect of improving the adhesion between an inorganic compound and an organic compound so far, and can improve the adhesion between a plating metal and a water-dispersible resin. When the above-mentioned specific surface treatment composition is used for the known effects of such a silane coupling agent, the acid component contained in the surface treatment composition activates the plating film surface by etching, It is considered that extremely excellent adhesion between the plating metal and the film-forming resin can be obtained by chemically bonding the silane coupling agent with both the activated plating metal and the film-forming resin. That is, by adding a silane coupling agent and a specific acid component to the surface treatment composition, the adhesion between the plating metal and the film-forming resin is markedly greater than when the silane coupling agent is added alone. As a result, it is considered that the progress of corrosion of the plated metal is effectively suppressed and particularly excellent corrosion resistance can be obtained.

  Although the mechanism by which the pseudo two-layer film having the above-described film structure is formed is not necessarily clear, the reaction between the acid component in the surface treatment composition and the surface of the plating film may be involved in the film formation. On the other hand, the following actions involving a silane coupling agent are also conceivable. That is, since the silane coupling agent hydrolyzed in an aqueous solution has a silanol group (Si—OH), the hydrogen bonding adsorption action of the silane coupling agent on the surface of the plating metal activated by the acid component is promoted. When the silane coupling agent is concentrated on the metal surface and then dried, a dehydration condensation reaction takes place to form a strong chemical bond, thereby inactivating the reaction layer (b) above the coating layer (ie, the plating coating surface layer). (Reaction layer with plating metal) is formed, and the barrier layer of (a) above (that is, a high barrier layer serving as a diffusion barrier for corrosion factors) is formed by the water-dispersible resin concentrated on the upper part of the film. There is also a possibility by the mechanism. In addition, there is a possibility that the above-described action occurs in a composite manner. In addition, in the film formation process as described above, it is considered that a reaction product (compound) between a dissolved plating metal such as zinc and an acid component is deposited in the film.

  Although the anticorrosion mechanism of such a pseudo-bilayer coating is not necessarily clear, the individual anticorrosion mechanism includes a dense organic polymer by adding a hydrazine derivative to a specific modified epoxy resin as the barrier layer of (a) above. A molecular film is formed, which suppresses the permeation of corrosion factors (oxygen, water, chlorine ions, etc.) and effectively suppresses the cathodic reaction that causes corrosion, and also prevents the plating metal ions eluted by the corrosion reaction. The free hydrazine derivative in the film traps to form a stable insoluble chelate compound layer, and the reaction layer in (b) above effectively inactivates the surface layer of the plating film to effectively cause an anodic reaction that causes corrosion. In addition, the precipitated compounds deposited in the film dissolve in a corrosive environment and acid components (phosphate ions, etc.) are generated. A self-repairing action that captures metal ions such as zinc ions eluted from the film (bonds with metal ions to form an insoluble compound), and is a plated metal in which a silane coupling agent is activated by an acid component. It is possible to form a dense film with high adhesion by binding to the surface firmly, suppressing dissolution of the plating metal, and also bonding with the film-forming resin. It is considered that extremely excellent corrosion resistance (white rust resistance) can be obtained.

The above is the basic composition and anticorrosion mechanism of the surface treatment film, but the present inventors have found that particularly excellent corrosion resistance can be obtained by further incorporating a specific fluorine compound in the surface treatment composition. It was. That is, by blending a fluorine compound into the surface treatment composition, the fluorine compound coexists with the acid component to form a film made of (HF) n having excellent barrier properties, thereby dramatically improving the corrosion resistance. I think that the.
Further, by adding a non-chromium rust preventive additive to the surface treatment composition, further excellent corrosion resistance can be obtained. The non-chromium rust preventive additive provides a further excellent anticorrosion performance because a protective film is formed at the starting point of corrosion.

  The above is the anticorrosion mechanism of the surface treatment film obtained by the specific treatment composition, but according to the results of the study by the present inventors, an organic film was simply formed on such a surface treatment film or an upper layer thereof. In the two-layer coating structure, it was found that, particularly when subjected to severe processing such as a wrinkle presser bead in an automobile press die, the processed portion was greatly damaged and its corrosion resistance was considerably inferior. Furthermore, it has been found that the damaged part of the film is damaged by the alkaline degreasing performed to remove the oil after the processing, and the corrosion resistance is further deteriorated. Therefore, as a result of studying the coating composition that is highly satisfied with the corrosion resistance of the processed part when subjected to such severe processing and further subjected to alkaline degreasing, the number average molecular weight is formed as the second layer coating on the surface treatment coating described above. Contains a high-molecular-weight epoxy group-containing resin having a molecular weight of 6000 to 20000, preferably a high-level anticorrosion even in a portion subjected to severe processing and alkaline degreasing as described above, by forming a film mainly composed of this resin. It turns out that an effect is acquired. That is, the present invention has been found that by combining the specific surface treatment film (lower film) and the specific high molecular weight resin film, particularly high corrosion resistance of the processed part can be obtained by their combined action. .

The present invention has been made on the basis of such findings, and the features thereof are as follows.
[1] The coating thickness formed by applying and drying a surface treatment composition containing the following components (a) to (d) on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet is 0.01 to Having a surface treatment film of 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified A resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with an active hydrogen-containing compound comprising a hydrazine derivative (C) in which some or all of the compounds have active hydrogen is used in water. Dispersed aqueous epoxy resin dispersion (b) Silane coupling agent: 1 to 300 parts by mass of solid content with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion (c) phosphoric acid and / or Or phosphoric acid compound: based on 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion 0.1 to 80 parts by weight in a ratio of solid content (d) trifluoride vanadium, one or more selected from among tetrafluoride vanadium solid the resin solid content 100 parts by weight of the aqueous epoxy resin dispersion 0.1 to 100 parts by weight in a proportion of minutes Formed by applying an upper layer coating composition containing a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 to the upper layer and drying. A highly corrosion-resistant surface-treated steel sheet, characterized in that it has an upper film having a coated film thickness of 0.3 to 2.0 μm.

[2] In the surface-treated steel sheet according to [1], the surface treatment composition for forming a surface treatment film further includes a non-chromium rust preventive additive, and a resin solid content 100 of the aqueous epoxy resin dispersion of component (a). A highly corrosion-resistant surface-treated steel sheet containing 0.1 to 50 parts by mass of solids with respect to parts by mass.
[3] In the surface-treated steel sheet according to [1] or [2], the coating composition for the upper layer film further contains a non-chromium rust preventive additive with a solid content of 100 parts by mass of the resin solid content of the coating composition. The high corrosion-resistant surface-treated steel sheet, characterized by containing 0.1 to 50 parts by mass of
[4] In the surface-treated steel sheet according to any one of [1] to [3], the surface treatment composition for forming the surface treatment film and / or the coating composition for the upper layer film is used as a non-chromium rust preventive additive, A highly corrosion-resistant surface-treated steel sheet comprising one or more selected from (e1) to (e7).
(E1) Silicon oxide (e2) Calcium and / or calcium compound (e3) Slightly soluble phosphate compound (e4) Molybdate compound (e5) Selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms (e6) Vanadium compounds (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds

[5] In the surface-treated steel sheet according to any one of the above [1] to [4], the coating composition for an upper film further includes a curing agent having a group that crosslinks with a hydroxyl group of the high molecular weight epoxy group-containing resin (E). A highly corrosion-resistant surface-treated steel sheet containing 1 to 50 parts by mass of solids with respect to 100 parts by mass of solids.
[6] In the surface-treated steel sheet according to [5], the curing agent having a group that crosslinks with a hydroxyl group is an amino resin (F) having an average of one or more imino groups in one molecule. Surface treated steel sheet.
[7] The surface-treated steel sheet according to [5], wherein the curing agent having a group capable of crosslinking with a hydroxyl group is a polyisocyanate compound (G) having an average of 4 or more isocyanate groups in one molecule. Corrosion-resistant surface-treated steel sheet.

[8] The surface-treated steel sheet according to [7], wherein the polyisocyanate compound (G) is obtained by blocking at least a part of isocyanate groups of the polyisocyanate compound with a blocking agent. steel sheet.
[9] In the surface-treated steel sheet according to any one of [1] to [8] above, the high molecular weight epoxy group-containing resin (E) is an activity comprising a hydrazine derivative (I) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet, which is a modified epoxy group-containing resin modified with a hydrogen-containing compound (H).
[10] In the surface-treated steel sheet according to any one of [1] to [9], the upper layer coating composition further includes a solid lubricant with a solid content of 100 parts by mass of the resin solid content of the coating composition. A highly corrosion-resistant surface-treated steel sheet containing 1 to 30 parts by mass in a proportion.

[11] A surface treatment composition containing the following components (a) to (d) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified A resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with an active hydrogen-containing compound comprising a hydrazine derivative (C) in which some or all of the compounds have active hydrogen is used in water. Dispersed aqueous epoxy resin dispersion (b) Silane coupling agent: 1 to 300 parts by mass of solid content with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion (c) phosphoric acid and / or Or phosphoric acid compound: based on 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion 0.1 to 80 parts by weight in a ratio of solid content (d) trifluoride vanadium, one or more selected from among tetrafluoride vanadium solid the resin solid content 100 parts by weight of the aqueous epoxy resin dispersion 0.1 to 100 parts by mass in the proportion of minutes The upper layer coating composition containing a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 is applied to the upper layer, and the ultimate plate temperature is 30 A method for producing a highly corrosion-resistant surface-treated steel sheet, wherein an upper layer film having a film thickness of 0.3 to 2.0 μm is formed by drying at a temperature of ˜150 ° C.

  The surface-treated steel sheet of the present invention has a very excellent flat plate and post-processing corrosion resistance despite the fact that it does not contain chromium in the film, and also has excellent weldability and paintability. For this reason, the surface-treated steel sheet of the present invention is particularly useful for automobile applications.

The details of the present invention and the reasons for limitation will be described below.
Examples of the zinc-based plated steel sheet used as the base of the surface-treated steel sheet of the present invention include galvanized steel sheet, Zn-Ni alloy-plated steel sheet, Zn-Fe alloy-plated steel sheet (electroplated steel sheet, galvannealed steel sheet), Zn-Cr. Alloy-plated steel sheet, Zn-Mn alloy-plated steel sheet, Zn-Co alloy-plated steel sheet, Zn-Co-Cr alloy-plated steel sheet, Zn-Cr-Ni alloy-plated steel sheet, Zn-Cr-Fe alloy-plated steel sheet, Zn-Al alloy plating Steel plate (for example, Zn-5% Al alloy-plated steel plate, Zn-55% Al alloy-plated steel plate), Zn-Mg alloy-plated steel plate, Zn-Al-Mg alloy-plated steel plate (for example, Zn-6% Al-3% Mg) Alloy-plated steel sheets, Zn-11% Al-3% Mg alloy-plated steel sheets), and metal oxides, polymers, etc. are dispersed in the plating film of these plated steel sheets Zinc-based composite-plated steel sheet (for example, Zn-SiO ₂ dispersion plating steel plate) was the like can be used.

In addition, among the above-described plating, a multi-layer plated steel sheet in which two or more layers of the same type or different types are plated can also be used.
Moreover, as an aluminum system plated steel plate used as the base of the surface treatment steel plate of this invention, an aluminum plating steel plate, an Al-Si alloy plating steel plate, etc. can be used.
Moreover, as a plated steel plate, the steel plate surface may be previously plated with lightness such as Ni, and various plating as described above may be performed thereon.
As a plating method, any feasible method among an electrolytic method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method, and a gas phase method can be adopted.
Furthermore, for the purpose of preventing blackening of the plating, a trace element of about 1 to 2000 ppm of Ni, Co, Fe is deposited in the plating film, or an alkaline aqueous solution containing Ni, Co, Fe on the surface of the plating film or acidic You may make it surface-treat with an aqueous solution and precipitate these elements.

Next, the surface treatment film formed as the first layer film and the surface treatment composition for forming this film on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet will be described.
In the surface-treated steel sheet of the present invention, the surface-treated film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet is applied with a surface treatment composition containing the following components (a) to (d) and dried. It is the surface treatment film | membrane formed by this. This surface treatment film does not contain any chromium.
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C) as necessary. Aqueous epoxy resin dispersion obtained by dispersing the resin obtained by the reaction in water (b) Silane coupling agent: 1 to 1 in terms of solid content with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion 300 parts by mass (c) Phosphoric acid and / or phosphoric acid compound: of the aqueous epoxy resin dispersion 0.1 to 80 parts by mass of solid content with respect to 100 parts by mass of fat solid content (d) Compound containing 1 to 5 fluorine atoms in one molecule: 100 mass of resin solid content of the aqueous epoxy resin dispersion 0.1 to 100 parts by mass with respect to parts by solid content

First, the aqueous epoxy resin dispersion that is the component (a) will be described.
This aqueous epoxy resin dispersion includes a specific polyalkylene glycol-modified epoxy resin (A), an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and a hydrazine derivative (C) ) And, if necessary, a resin obtained by reacting an active hydrogen-containing compound (D) other than the hydrazine derivative (C), is dispersed in water.
The polyalkylene glycol-modified epoxy resin (A) is obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound, and a polyisocyanate compound. .

As the polyalkylene glycol, for example, polyethylene glycol, polypropylene glycol, polybutylene glycol and the like can be used, and among them, polyethylene glycol is particularly preferable. The number average molecular weight of the polyalkylene glycol is suitably in the range of 400 to 20000, preferably 500 to 10,000, from the viewpoint of water dispersibility and storage properties of the resulting resin.
The bisphenol-type epoxy resin is a bisphenol compound having at least one epoxy group in one molecule, and in particular, a bisphenol diester obtained by a condensation reaction between a bisphenol compound and an epihalohydrin (for example, epichlorohydrin). Glycidyl ether is preferable because a film excellent in flexibility and corrosion resistance can be easily obtained.

Typical examples of bisphenol compounds that can be used for the preparation of bisphenol-type epoxy resins include bis (4-hydroxyphenyl) -2,2-propane, bis (4-hydroxyphenyl) -1,1-ethane, and bis. (4-hydroxyphenyl) -methane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-3-t- Butylphenyl) -2,2-propane and the like. Of the epoxy resins prepared using such bisphenol-based compounds, bisphenol A type epoxy resins are particularly suitable in that a film excellent in flexibility and corrosion resistance can be obtained.
Further, the bisphenol type epoxy resin generally has a number average molecular weight of about 310 to 10,000, particularly preferably about 320 to 2,000, from the viewpoint of production stability during production of the polyalkylene glycol-modified epoxy resin. The epoxy equivalent is preferably in the range of about 155 to 5000, particularly desirably about 160 to 1000.

  The active hydrogen-containing compound is used for blocking isocyanate groups in the polyalkylene glycol-modified epoxy resin (A). Typical examples thereof include monohydric alcohols such as methanol, ethanol and diethylene glycol monobutyl ether; monovalent carboxylic acids such as acetic acid and propionic acid; monovalent thiols such as ethyl mercaptan. Other blocking agents (active hydrogen-containing compounds) include secondary amines such as diethylamine; one secondary amino group or hydroxyl group such as diethylenetriamine and monoethanolamine and one or more primary groups. A compound in which the primary amino group of an amine compound containing an amino group is modified to aldimine, ketimine, oxazoline or imidazoline by heating reaction with a ketone, aldehyde or carboxylic acid at a temperature of, for example, 100 to 230 ° C .; methyl ethyl ketoxime And oximes such as phenol; phenols such as phenol and nonylphenol; These compounds generally have a number average molecular weight in the range of 30 to 2000, particularly preferably 30 to 200.

  The polyisocyanate compound is a compound having 2 or more, preferably 2 or 3 isocyanate groups in one molecule, and those generally used for the production of polyurethane resins can be used in the same manner. Such polyisocyanate compounds include aliphatic, alicyclic and aromatic polyisocyanate compounds. Representative examples include aliphatic polyisocyanate compounds such as hexamethylene diisocyanate (HMDI), HMDI biuret compound, HMDI isocyanurate compound; isophorone diisocyanate (IPDI), IPDI biuret compound, IPDI isocyanurate compound, Examples thereof include alicyclic polyisocyanate compounds such as hydrogenated xylylene diisocyanate and hydrogenated 4,4′-diphenylmethane diisocyanate; aromatic polyisocyanate compounds such as tolylene diisocyanate and xylylene diisocyanate.

In general, the blending ratio of each component during the production of the polyalkylene glycol-modified epoxy resin (A) is suitably in the following range.
That is, the equivalent ratio of the hydroxyl group of the polyalkylene glycol to the isocyanate group of the polyisocyanate compound is 1 / 1.2 to 1/10, preferably 1 / 1.5 to 1/5, particularly preferably 1 / 1.5 to A value of 1/3 is appropriate. The equivalent ratio of the hydroxyl group of the active hydrogen-containing compound to the isocyanate group of the polyisocyanate compound is 1/2 to 1/100, preferably 1/3 to 1/50, particularly preferably 1/3 to 1/20. Is appropriate. The equivalent ratio of the total amount of hydroxyl groups of the polyalkylene glycol, the bisphenol type epoxy resin and the active hydrogen-containing compound to the isocyanate group of the polyisocyanate compound is 1 / 1.5 or less, preferably 1 / 0.1 to 1/1. .5, particularly preferably 1 / 0.1 to 1 / 1.1.

The reaction of the polyalkylene glycol, the bisphenol type epoxy resin, the active hydrogen-containing compound and the polyisocyanate compound can be performed by a known method.
The polyalkylene glycol-modified epoxy resin (A) obtained above, an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and further necessary Accordingly, by reacting with the active hydrogen-containing compound (D) other than the hydrazine derivative (C), an epoxy resin that can be easily dispersed in water and has good adhesion to the material can be obtained. .

As the epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a glycidyl group is introduced by reacting polyphenols such as bisphenol A, bisphenol F, and novolac type phenol with an epihalohydrin such as epichlorohydrin. Or an aromatic epoxy resin obtained by further reacting this glycidyl group-introduced reaction product with a polyphenol to increase the molecular weight; and further, an aliphatic epoxy resin, an alicyclic epoxy resin, etc. One kind can be used alone, or two or more kinds can be mixed and used. These epoxy resins preferably have a number average molecular weight of 1500 or more, particularly when film formation at low temperatures is required.
Examples of the epoxy group-containing resin (B) include resins obtained by reacting various modifiers with epoxy groups or hydroxyl groups in the epoxy group-containing resin. For example, epoxy ester resins obtained by reacting a dry oil fatty acid. An epoxy acrylate resin modified with a polymerizable unsaturated monomer component containing acrylic acid or methacrylic acid; a urethane-modified epoxy resin reacted with an isocyanate compound;

Further, as the epoxy group-containing resin (B), an unsaturated monomer having an epoxy group and a polymerizable unsaturated monomer component essentially comprising an acrylic ester or a methacrylic ester are used as a solution polymerization method, emulsion polymerization method or suspension polymerization method. An acrylic copolymer resin copolymerized with an epoxy group-containing monomer synthesized by a method such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl ( Acrylic acid or methacrylic acid such as (meth) acrylate, n-, iso- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate C1-C24 Alkyl ester; acrylic acid, methacrylic acid, styrene, vinyl toluene, acrylamide, acrylonitrile, N-methylol (meth) acrylamide, C1-4 alkyl etherified product of N-methylol (meth) acrylamide; N, N-diethylaminoethyl methacrylate, etc. Can be mentioned. Moreover, as an unsaturated monomer which has an epoxy group, if it has an epoxy group and a polymerizable unsaturated group, such as glycidyl methacrylate, glycidyl acrylate, and 3,4 epoxy cyclohexyl-1-methyl (meth) acrylate, It is not limited.
The acrylic copolymer resin may be a resin modified with a polyester resin, an epoxy resin, a phenol resin, or the like.

上記化学構造式中、ｑは０〜５０の整数、好ましくは１〜４０の整数、特に好ましくは２〜２０の整数である。
このようなビスフェノールＡ型エポキシ樹脂は、当業界において広く知られた製造法により得ることができる。 Particularly preferable as the epoxy group-containing resin (B) is a resin represented by the following chemical structural formula, which is a reaction product of bisphenol A and epiparohydrin, and is particularly preferable because of its excellent corrosion resistance.

In said chemical structural formula, q is an integer of 0-50, Preferably it is an integer of 1-40, Most preferably, it is an integer of 2-20.
Such a bisphenol A type epoxy resin can be obtained by a production method widely known in the art.

Examples of the active hydrogen-containing compound that reacts with the epoxy group of the epoxy group-containing resin (B) include the following.
・ Hydrazine derivatives with active hydrogen ・ Primary or secondary amine compounds with active hydrogen ・ Organic acids such as ammonia and carboxylic acids ・ Hydrogen halides such as hydrogen chloride ・ Alcohols, thiols ・ Active hydrogen Quaternary chlorinating agent which is a mixture of hydrazine derivative or tertiary amine and acid which does not have, when adjusting the aqueous epoxy resin dispersion, one or more of these can be used, but excellent corrosion resistance In order to obtain, at least a part (preferably all) of the active hydrogen-containing compound needs to be a hydrazine derivative having active hydrogen. That is, among these, a hydrazine derivative (C) having active hydrogen is an essential component, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C) is used as necessary.

The following can be mentioned as a typical example of the amine compound which has the said activated hydrogen.
(1) a primary amino group of an amine compound containing one secondary amino group and one or more primary amino groups, such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, etc .; A compound modified with aldimine, ketimine, oxazoline or imidazoline by heat reaction with aldehyde or carboxylic acid at a temperature of about 100 to 230 ° C., for example;
(2) Secondary monoamines such as diethylamine, diethanolamine, di-n- or -ios-propanolamine, N-methylethanolamine, N-ethylethanolamine;
(3) a secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and a dialkyl (meth) acrylamide by a Michael addition reaction;
(4) A compound obtained by modifying a primary amine group of an alkanolamine such as monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 ′ (aminopropoxy) ethyl ether to ketimine;

  The quaternary chlorinating agent that can be used as a part of the active hydrogen-containing compound can react with an epoxy group because a hydrazine derivative or a tertiary amine that does not have an active hydrogen is not reactive with an epoxy group by itself. Therefore, it is a mixture with an acid. The quaternary chlorinating agent reacts with an epoxy group in the presence of water as necessary to form a quaternary salt with the epoxy group-containing resin. The acid used to obtain the quaternary chlorinating agent may be any of organic acids such as acetic acid and lactic acid, and inorganic acids such as hydrochloric acid. Examples of the hydrazine derivative having no active hydrogen used for obtaining a quaternary chlorinating agent include 3,6-dichloropyridazine, and examples of the tertiary amine include dimethylethanolamine, triethylamine, Examples include trimethylamine, triisopropylamine, and methyldiethanolamine.

It is a hydrazine derivative having active hydrogen that exhibits the most useful and excellent corrosion resistance performance among the active hydrogen-containing compounds.
Specific examples of the hydrazine derivative having active hydrogen include the following.
(1) Carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonyl hydrazide, benzophenone hydrazone, aminopolyacrylamide Hydrazide compounds such as;
(2) pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole;

 (3) 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino -3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6- Triazole compounds such as methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine;

(4) tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole;
(5) thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole;
(6) Maleic hydrazide, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone, etc. Pyridazine compounds;
Of these, pyrazole compounds and triazole compounds having a 5-membered or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly suitable.
These hydrazine derivatives can be used individually by 1 type or in mixture of 2 or more types.

  A polyalkylene glycol-modified epoxy resin (A) as described above, an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and further necessary The active hydrogen-containing compound (D) other than the hydrazine derivative (C) is preferably reacted at a temperature of 10 to 300 ° C., more preferably 50 to 150 ° C. for about 1 to 8 hours. The aqueous epoxy resin dispersion described above can be obtained by dispersing the resin in water.

  The above reaction may be performed by adding an organic solvent, and the type of the organic solvent to be used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether , Propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and other alcohols and ethers containing hydroxyl groups; ethyl acetate, butyl acetate, ethylene glycol monobutyl ether acetate and other esters; toluene, xylene Aromatic hydrocarbons, etc. Indicates possible, it is possible to use one or more of these. Of these, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with an epoxy resin, film formation, and the like.

The blending ratio of the polyalkylene glycol-modified epoxy resin (A), the epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and the hydrazine derivative (C) having active hydrogen is polyalkylene glycol-modified. The equivalent ratio of active hydrogen groups in the hydrazine derivative (C) to the epoxy groups in the epoxy resin (A) and the epoxy group-containing resin (B) is 0.01 to 10, preferably 0.1 to 8, and more preferably 0. 2 to 4 is appropriate from the viewpoints of corrosion resistance and water dispersibility of the resin.
Further, as described above, a part of the hydrazine derivative (C) having active hydrogen can be replaced with the active hydrogen-containing compound (D), but the amount to be replaced (that is, the active hydrogen-containing compound including the hydrazine derivative (C)) The proportion of the active hydrogen-containing compound (D) in the composition is 90 mol% or less, preferably 70 mol% or less, more preferably 10 to 60 mol%, from the viewpoint of corrosion resistance and adhesion. It is.

  Moreover, in order to form a dense barrier film, it is desirable to mix a curing agent in the resin composition and heat cure the film. The curing method for forming a film with the resin composition was selected from (1) a curing method using a urethanization reaction between an isocyanate and a hydroxyl group in a base resin, and (2) melamine, urea, and benzoguanamine. Etherification reaction between an alkyl etherified amino resin obtained by reacting one or more methylol compounds obtained by reacting formaldehyde with one or more monovalent alcohols having 1 to 5 carbon atoms and a hydroxyl group in the base resin. However, it is particularly preferable to use a urethanization reaction between an isocyanate and a hydroxyl group in the base resin as a main reaction.

The polyisocyanate compound as a curing agent that can be used in the curing method (1) is an aliphatic, alicyclic (including heterocyclic) or aromatic isocyanate compound having at least two isocyanate groups in one molecule. Or a compound obtained by partially reacting these compounds with a polyhydric alcohol. Examples of such polyisocyanate compounds include the following.
(i) m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate
(ii) The above compound (i) alone or a mixture thereof and a polyhydric alcohol (dihydric alcohols such as ethylene glycol and propylene glycol; trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric alcohols such as pentaerythritol; A compound obtained by reaction with a hexahydric alcohol such as sorbitol and dipentaerythritol), in which at least two isocyanates remain in one molecule. These polyisocyanate compounds may be used alone or in combination of two or more. Can be used in combination.

Moreover, as a protective agent (blocking agent) of a polyisocyanate compound, for example,
(1) Aliphatic monoalcohols such as methanol, ethanol, propanol, butanol, octyl alcohol;
(2) Ethylene glycol and / or diethylene glycol monoethers, for example, monoethers such as methyl, ethyl, propyl (n-, iso), butyl (n-, iso, sec);
(3) Aromatic alcohols such as phenol and cresol;
(4) oximes such as acetooxime and methyl ethyl ketone oxime;
A polyisocyanate compound that is stably protected at least at room temperature can be obtained by reacting one or more of these with the polyisocyanate compound.

  Such a polyisocyanate compound (a2) has a curing agent of (a) / (a2) = 95/5 to 55/45 (nonvolatile) with respect to the aqueous epoxy resin dispersion (a) (the component (a)). (Mass ratio of minute), preferably (a) / (a2) = 90/10 to 65/35. The polyisocyanate compound has water absorption, and if it is blended in excess of (a) / (a2) = 55/45, the adhesion of the surface treatment film is deteriorated. Furthermore, the unreacted polyisocyanate compound moves into the upper layer film, which causes inhibition of curing of the upper layer film and poor adhesion. From such a viewpoint, the blending amount of the polyisocyanate compound (a2) is preferably (a) / (a2) = 55/45 or less.

The water-dispersible resin is sufficiently crosslinked by the addition of the crosslinking agent (curing agent) as described above, but it is desirable to use a known curing accelerating catalyst in order to further increase the low-temperature crosslinking property. Examples of the curing accelerating catalyst include N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, and bismuth nitrate.
In addition, for the purpose of slightly improving physical properties such as adhesion, a known resin such as acrylic, alkyd, or polyester can be mixed and used together with the epoxy group-containing resin (B).

The reaction product of polyalkylene glycol-modified epoxy resin (A), epoxy group-containing resin (B) and hydrazine derivative (C) having active hydrogen (and active hydrogen-containing compound (D) if necessary) is dispersed in water. For example, the following method can be employed.
(1) A tertiary amine which is a neutralizing agent by reacting an epoxy group of an epoxy group-containing resin (ie, resin (A) or (B)) with a dibasic acid or secondary amine which is an active hydrogen-containing compound. , Neutralization with acetic acid or phosphoric acid, water dispersion method
(2) A method of dispersing in water using a modified epoxy resin obtained by reacting an epoxy resin with a terminal hydroxyl group-containing polyalkylene oxide such as polyethylene glycol or polypropylene glycol with an isocyanate.
(3) Method of using both (1) and (2) in combination In addition to the specific water-dispersible resin described above, other surface-dispersible resins and / or water-soluble resins include, for example, acrylic Resin, urethane resin, polyester resin, epoxy resin, ethylene resin, alkyd resin, phenol resin, olefin resin, etc. You may mix | blend as an upper limit.

Next, the silane coupling agent which is the said component (b) is demonstrated.
Examples of the silane coupling agent include vinyl methoxy silane, vinyl ethoxy silane, vinyl trichloro silane, vinyl trimethoxy silane, vinyl triethoxy silane, β- (3,4 epoxy cyclohexyl) ethyl trimethoxy silane, and γ-glycid. Xylpropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ -Aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-me Tacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, p-styryltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, γ-isocyanatopropyl Triethoxysilane, γ-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N- (vinylbenzylamine) -β-aminoethyl-γ-aminopropyltri Etc. can be mentioned Tokishishiran, these one may be used alone or in combination of two or more.

In the present invention, the reason described above is considered to improve the white rust resistance by including a silane coupling agent together with a specific acid component in the surface treatment composition.
Among the silane coupling agents, a silane coupling agent having an amino group as a reactive functional group is particularly preferable from the viewpoint of having a functional group highly reactive with the water-dispersible resin of the component (a). preferable. Examples of such silane coupling agents include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ. -Aminopropyltrimexysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, etc., specifically, “KBM-903” and “KBE-903” manufactured by Shin-Etsu Chemical Co., Ltd. , “KBM-603”, “KBE-602”, “KBE-603” (all are trade names), and the like.

  The compounding amount of the silane coupling agent is 1 to 300 parts by mass, preferably 5 to 100 parts by mass in terms of the solid content with respect to 100 parts by mass of the resin solid content of the aqueous epoxy resin dispersion as the component (a). More preferably, the content is 15 to 50 parts by mass. If the amount of the silane coupling agent is less than 1 part by mass, the corrosion resistance is inferior. On the other hand, if it exceeds 300 parts by mass, a sufficient film cannot be formed, so that the effect of improving the adhesion and barrier properties with the water-dispersible resin can be exhibited. Therefore, the corrosion resistance is reduced.

Next, phosphoric acid and / or a phosphoric acid compound as the component (c) has an action of activating the plated metal surface by acting on the inactive plated metal surface. The phosphoric acid and the phosphoric acid compound may be used alone or in combination.
The type of the phosphoric acid compound is not particularly limited, but a water-soluble phosphate is particularly preferable. For example, one or more metal salts such as orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, and metaphosphoric acid can be used. Moreover, you may add 1 or more types of the salt (for example, phytic acid, phytate, phosphonic acid, phosphonate, and these metal salts) of organic phosphoric acid. Of these, the primary phosphate is preferable from the viewpoint of the stability of the surface treatment composition.
There is no particular limitation on the form of phosphate present in the film, and it may be crystalline or non-crystalline. There are no particular restrictions on the ionicity and solubility of the phosphate in the film.

  As described above, the silane coupling agent chemically bonds with both the activated plating metal and the film-forming resin, thereby providing excellent adhesion and corrosion resistance between the plating metal and the film-forming resin. There are unavoidably inactive portions on the metal surface, and such an inactive site hardly causes the above-mentioned chemical bond and cannot sufficiently exhibit the rust prevention effect. The water-soluble phosphate forms a dense hardly soluble compound at the time of film formation on such a plated film portion. That is, as the plating film is dissolved by the phosphate ions of the water-soluble phosphate, the pH increases at the plating film / surface treatment composition interface, resulting in the formation of a precipitate film of the water-soluble phosphate, which is corrosion resistant. It contributes to the improvement.

From the viewpoint of obtaining particularly excellent corrosion resistance, Al, Mn, Ni, and Mg are particularly desirable as the cationic species of the water-soluble phosphate, and the water-soluble phosphorus containing one or more elements selected from these is preferred. It is preferable to use an acid salt. Examples of such water-soluble phosphates include primary aluminum phosphate, primary manganese phosphate, primary nickel phosphate, primary magnesium phosphate, and among these, primary aluminum phosphate is particularly preferable. Is most preferred. Moreover, it is preferable that the molar ratio [cation] / [P ₂ O ₅ ] of the cation component and the P ₂ O ₅ component is 0.4 to 1.0. If the molar ratio [cation] / [P ₂ O ₅ ] is less than 0.4, the solubility of the film is impaired by the soluble phosphoric acid, and the corrosion resistance is lowered. On the other hand, if it exceeds 1.0, the stability of the processing solution is remarkably lost, which is not preferable.

  The blending amount of the phosphoric acid and / or phosphoric acid compound is 0.1 to 80 parts by mass in total of the solid content with respect to 100 parts by mass of the resin solid content of the aqueous epoxy resin dispersion as the component (a). The amount is preferably 1 to 60 parts by mass, more preferably 5 to 50 parts by mass. If the blending amount of phosphoric acid and / or phosphoric acid compound is less than 0.1 parts by mass, the corrosion resistance is inferior. On the other hand, if it exceeds 80 parts by mass, the soluble component of the film increases, which is not preferable because the corrosion resistance decreases.

  Examples of the fluorine compound as the component (d), that is, a compound containing 1 to 5 fluorine atoms in one molecule include phosphoric acid compounds such as fluorophosphoric acid and calcium fluorophosphate; vanadium trifluoride, vanadium tetrafluoride, Metal compounds such as cesium fluoride, strontium fluoride, antimony fluoride, rubidium fluoride, magnesium fluoride, aluminum fluoride, cobalt fluoride, nickel fluoride, titanium fluoride, zirconium fluoride; tetrafluoroboric acid, fluorine Examples thereof include hydrofluoric acid and salts thereof. One of these may be used alone, or two or more thereof may be mixed and used. In particular, vanadium compounds such as vanadium trifluoride and vanadium tetrafluoride are preferable from the viewpoint of corrosion resistance. This is due to the passivation effect of vanadium, and the vanadium compound may be added alone to the fluorine compound.

  The compounding quantity of a fluorine compound is 0.1-100 mass parts in the ratio of solid content with respect to 100 mass parts of resin solid content of the aqueous | water-based epoxy resin dispersion which is the said component (a), Preferably 1-60 mass parts, More preferably, the content is 5 to 30 parts by mass. When the blending amount of the fluorine compound is less than 0.1 parts by mass, the corrosion resistance is inferior. On the other hand, when it exceeds 100 parts by mass, the solution state becomes unstable, the corrosion resistance is lowered, and it is economically disadvantageous.

A non-chromium rust preventive additive can be blended with the surface treatment composition as needed for the purpose of improving corrosion resistance. Particularly excellent anticorrosion performance (self-repairing property) can be obtained by blending such a non-chromium rust preventive additive into the surface treatment composition.
In particular, it is preferable to use one or more selected from the following (e1) to (e7) as the non-chromium rust preventive additive.
(E1) silicon oxide (e2) calcium or / and calcium compound (e3) sparingly soluble phosphate compound (e4) molybdate compound (e5) selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms (e6) Vanadium compounds (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Organic compounds to be contained The details and anticorrosion mechanisms of the non-chromium rust preventive additives (e1) to (e7) are as follows.

First, as the component (e1), colloidal silica or dry silica, which is fine particle silica, can be used. From the viewpoint of corrosion resistance, calcium ion-exchanged silica in which calcium is bound to the surface is used. Is desirable.
As colloidal silica, for example, Snowtex O, 20, 30, 40, C, S (all trade names) manufactured by Nissan Chemical Co., Ltd. can be used, and as fumed silica, Nippon Aerosil ( AEROSIL R971, R812, R811, R974, R202, R805, 130, 200, 300, and 300CF (all trade names) manufactured by Co., Ltd. can be used. As calcium ion exchange silica, WRGrace & Co. SHIELDEX C303, SHIELDEX AC3, SHIELDEX AC5 (all are trade names) manufactured by SHIELDEX, SHIELDEX, SHIELDEX SY710 (all are trade names) manufactured by Fuji Silysia Chemical Co., Ltd., etc. can be used. These silicas contribute to the production of dense and stable zinc corrosion products in a corrosive environment, and the corrosion products are formed densely on the plating surface, thereby suppressing the promotion of corrosion.

In addition, the above components (e2) and (e3) exhibit particularly excellent anticorrosion performance (self-repairing property) due to precipitation.
The calcium compound as the component (e2) may be any of calcium oxide, calcium hydroxide, and calcium salt, and one or more of these can be used. In addition, there are no particular restrictions on the type of calcium salt. In addition to simple salts containing only calcium as a cation such as calcium silicate, calcium carbonate, and calcium phosphate, calcium and calcium such as calcium phosphate / zinc, calcium phosphate / magnesium, etc. Double salts containing other cations may be used. The components (e2) is baser calcium than zinc and aluminum as the plating metal in a corrosive environment is preferentially dissolved, this OH produced by the cathode reaction ^- sequestering defective portion as a product of dense and poorly soluble And suppress the corrosion reaction. Moreover, when it mix | blends with the above silicas, a calcium ion adsorb | sucks to the surface and neutralizes a surface charge electrically and aggregates. As a result, a dense and sparingly soluble protective film is formed to block the corrosion and suppress the corrosion reaction.

  Further, as the hardly soluble phosphate compound (e3), a hardly soluble phosphate can be used. This sparingly soluble phosphate includes all types of salts such as simple salts and double salts. Moreover, there is no limitation in the metal cation which comprises it, and any metal cation, such as poorly soluble zinc phosphate, magnesium phosphate, calcium phosphate, aluminum phosphate, may be sufficient. Further, there is no limitation on the skeleton or the degree of condensation of phosphate ions, and any of normal salt, dihydrogen salt, monohydrogen salt or phosphite may be used. In addition, orthophosphate may be polyphosphate other than orthophosphate. Includes all condensed phosphates such as salts. By using this poorly soluble phosphorus compound, the plating metal zinc or aluminum eluted by corrosion reacts with the phosphate ions dissociated by hydrolysis to form a dense and sparingly soluble protective film. The corrosion starting point is blocked, and the corrosion reaction is suppressed.

  As the molybdate compound (e4), for example, molybdate can be used. The molybdate is not limited in its skeleton and degree of condensation, and examples thereof include orthomolybdate, paramolybdate, and metamolybdate. Moreover, all salts, such as a single salt and a double salt, are included, and phosphoric acid molybdate etc. are mentioned as a double salt. Molybdate compounds exhibit self-repairing properties due to the passivating effect. That is, by forming a dense oxide on the plating film surface together with dissolved oxygen in a corrosive environment, the corrosion starting point is blocked and the corrosion reaction is suppressed.

Examples of the organic compound (e5) include the following. That is, as triazoles, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino-3-mercapto-1,2 1,4-triazole, 1H-benzotriazole, etc., and as thiols, 1,3,5-triazine-2,4,6-trithiol, 2-mercaptobenzimidazole, etc., and as thiadiazoles, 5- Amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole and the like, and as thiazoles, 2-N, N-diethylthiobenzothiazole, 2-mercapto Examples include benzothiazoles, and examples of thiurams include tetraethylthiuram disulfide. It is. These organic compounds exhibit self-repairing properties due to the adsorption effect. That is, zinc and aluminum eluted by corrosion are adsorbed to polar groups containing sulfur contained in these organic compounds to form an inert film, thereby blocking the corrosion starting point and suppressing the corrosion reaction.
As the vanadium compound (e6), for example, a pentavalent vanadium compound or a tetravalent vanadium compound can be applied. In particular, a tetravalent vanadium compound is preferable from the viewpoint of corrosion resistance.

  Examples of the organic compound (e7) include the following. That is, hydrazide compounds include carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, benzophenone. , Aminopolyacrylamide, etc .; as pyrazole compounds, pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole, etc .; as triazole compounds, 1,2,4-triazole 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino-3-mercapto-1,2, -Triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6-methyl-8-hydroxytriazolopyridazine, 6 -Phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine, etc .; tetrazole compounds include 5-phenyl-1,2,3,4-tetrazole, 5 -Mercapto-1-phenyl-1,2,3,4-tetrazole and the like; As thiadiazole compounds, 5-amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4 -Thiadiazole and the like; as pyridazine compounds, maleic hydrazide, 6-methyl-3-pyridazone, 4, - dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, such as 6-methyl-4,5-dihydro-3-pyridazone and the like. Of these, pyrazole compounds and triazole compounds having a 5- or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly suitable.

The compounding amount of the non-chromium rust preventive additive is 0.1 to 50 parts by mass, preferably 100 to 50 parts by mass of the solid content of the aqueous epoxy resin dispersion as the component (a). It is appropriate that the content is 0.5 to 30 parts by mass. If the blending amount of the non-chromium rust preventive additive is less than 0.1 parts by mass, the effect of improving the corrosion resistance after alkali degreasing cannot be sufficiently obtained. In addition, the corrosion resistance is reduced, which is not preferable.
Two or more rust preventive additives (e1) to (e7) may be added in combination. In this case, since the inherent anticorrosive action is combined, higher corrosion resistance can be obtained. In particular, calcium ion-exchanged silica is used as the above component (e1), and one or more of the components (e3) to (e5), particularly preferably all of the components (e3) to (e5) are added to this. In particular, excellent corrosion resistance can be obtained.

In the surface treatment film (and surface treatment composition), other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, etc.), phosphomolybdate as corrosion inhibitors. One or two or more of organic inhibitors (for example, hydrazine and its derivatives, thiol compounds, thiocarbamates, etc.) can be added.
Further, if necessary, in the surface treatment film (and surface treatment composition), as an additive, an organic coloring pigment (for example, condensed polycyclic organic pigment, phthalocyanine organic pigment, etc.), a coloring dye (for example, water-soluble) Azo metal dyes), inorganic pigments (eg, titanium oxide), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide, etc.), coupling agents (eg, 1 type, or 2 or more types, such as a titanium coupling agent etc.) and a melamine cyanuric acid adduct.
The surface treatment film formed by the surface treatment composition containing the above components has a dry film thickness of 0.01 to 1.0 μm, preferably 0.1 to 0.8 μm. When the dry film thickness is less than 0.01 μm, the corrosion resistance is insufficient. On the other hand, when the dry film thickness exceeds 1.0 μm, the conductivity and workability are lowered.

Next, the upper layer film (organic film) formed as the second layer film on the surface treatment film will be described.
This upper layer film is formed by applying and drying a coating composition for an upper layer film containing a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000, preferably comprising this as a main component resin. The film thickness is 0.3 to 2.0 μm. This upper layer film also contains no chromium. By forming such a specific high molecular weight resin film on the upper layer of the specific surface treatment film (lower film), particularly high corrosion resistance of the processed part can be obtained by the combined action of both films.

In the present invention, the reason why the epoxy group-containing resin (E) is used for the upper layer film is that the aspects such as reactivity, easiness of reaction, and anticorrosion are superior to those of other resins. Examples of the epoxy group-containing resin (E) include an epoxy resin, a modified epoxy resin, an acrylic copolymer resin copolymerized with an epoxy group-containing monomer, a polybutadiene resin having an epoxy group, a polyurethane resin having an epoxy group, and Examples include adducts or condensates of these resins, and one of these epoxy group-containing resins can be used alone or in admixture of two or more.
Of these epoxy group-containing resins (E), epoxy resins and modified epoxy resins are particularly preferred from the viewpoints of adhesion to the plating surface and corrosion resistance. Of these, thermosetting epoxy resins and modified epoxy resins with excellent barrier properties against corrosive factors such as oxygen are the most suitable, with a particularly low coating level for high spot weldability. This is particularly advantageous.

  As the epoxy group-containing resin (E), a high molecular weight epoxy group-containing resin having a number average molecular weight of 6000 to 20000, preferably 7000 to 12000 is used. Among these, bisphenol type epoxy resins are preferable. Generally used bisphenol type epoxy resins have a number average molecular weight of 5500 or less, but if the number average molecular weight is less than 6000, the processability of the resulting film is not sufficient, especially for automotive press dies. The film damage when subjected to severe processing by a certain wrinkle presser bead is large, and the corrosion resistance of the processed part is inferior. On the other hand, when the number average molecular weight exceeds 20000, it is very difficult to produce an epoxy resin, and it becomes difficult to obtain a product having a stable quality due to gelation or the like.

  Examples of the bisphenol type epoxy resin include a resin obtained by condensing epichlorohydrin and bisphenol up to a high molecular weight in the presence of a catalyst such as an alkali catalyst, if necessary, and epichlorohydrin and bisphenol, if necessary, an alkali catalyst. Any of the resins obtained by condensation in the presence of a catalyst to form a low molecular weight epoxy resin and a polyaddition reaction of this low molecular weight epoxy resin and bisphenol may be used. The latter method is preferred for obtaining the above.

  Examples of the bisphenol include bis (4-hydroxyphenyl) methane [bisphenol F], 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2,2-bis (4-hydroxyphenyl) butane [bisphenol B], bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, Examples thereof include p- (4-hydroxyphenyl) phenol, oxybis (4-hydroxyphenyl), sulfonylbis (4-hydroxyphenyl), 4,4′-dihydroxybenzophenone, bis (2-hydroxynaphthyl) methane, and the like. Bis (4-hydroxyphenyl) methane Bisphenol F] and 2,2-bis (4-hydroxyphenyl) propane [bisphenol A] is preferable. The said bisphenol can be used individually by 1 type or in mixture of 2 or more types.

As said modified | denatured epoxy resin, an acrylic modified epoxy resin, a polyester modified epoxy resin, a urethane modified epoxy resin etc. can be mentioned, for example. Also, polyalkylene glycol-modified epoxy resin obtained by reacting polyalkylene glycol, polyisocyanate and epoxy resin, modified by reacting an epoxy resin with an active hydrogen-containing compound comprising a hydrazine derivative in which some or all of the compounds have active hydrogen. Epoxy resins (hydrazine derivative-modified epoxy resins) can also be used. Of these, hydrazine derivative-modified epoxy resins are particularly preferred from the standpoint of improving corrosion resistance.
The modified epoxy resin may be one obtained by reacting various modifiers with the epoxy group or hydroxyl group in the epoxy resin, and includes, for example, an epoxy ester resin obtained by reacting a dry oil fatty acid, acrylic acid or methacrylic acid. Examples thereof include an epoxy acrylate resin modified with a polymerizable unsaturated monomer component and a urethane-modified epoxy resin reacted with an isocyanate compound.

As the acrylic copolymer resin copolymerized with the epoxy group-containing monomer, an unsaturated monomer having an epoxy group and a polymerizable unsaturated monomer component essentially comprising an acrylic ester or a methacrylic ester, a solution polymerization method, Examples thereof include resins synthesized by an emulsion polymerization method or a suspension polymerization method.
Examples of the polymerizable unsaturated monomer component include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-, iso- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, C1-24 alkyl ester of acrylic acid or methacrylic acid such as 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate; acrylic acid, methacrylic acid, styrene, vinyltoluene, acrylamide, acrylonitrile, N- Examples thereof include methylol (meth) acrylamide, C1-4 alkyl etherified product of N-methylol (meth) acrylamide; N, N-diethylaminoethyl methacrylate and the like.
The unsaturated monomer having an epoxy group is not particularly limited as long as it has an epoxy group and a polymerizable unsaturated group, such as glycidyl methacrylate, glycidyl acrylate, and 3,4-epoxycyclohexylmethyl (meth) acrylate. .

  An active hydrogen-containing compound (H) composed of a hydrazine derivative (I) in which some or all of the compounds represented by the hydrazine derivative-modified epoxy resin have active hydrogen is reacted with a high molecular weight epoxy group-containing resin (E). The modified epoxy group-containing resin has improved adhesion to the base and particularly excellent corrosion resistance by the reaction of the hydrazine derivative (I) having active hydrogen with the epoxy group of the high molecular weight epoxy group-containing resin (E). A film can be formed.

Examples of the active hydrogen-containing compound (H) that reacts with the epoxy group of the high molecular weight epoxy group-containing resin (E) include those shown below, and one or more of these can be used. In some cases, at least a part (preferably all) of the active hydrogen-containing compound (H) needs to be the hydrazine derivative (I) having active hydrogen. That is, among these, the hydrazine derivative (I) having active hydrogen is an essential component, and an active hydrogen-containing compound (H) other than the hydrazine derivative (I) is used as necessary.
・ Hydrazine derivatives with active hydrogen ・ Primary or secondary amine compounds with active hydrogen ・ Organic acids such as ammonia and carboxylic acids ・ Halogen halides such as hydrogen chloride ・ Alcohols and thiols ・ Having active hydrogen Quaternary chlorinating agent which is a mixture of hydrazine derivative or tertiary amine and acid

Examples of the hydrazine derivative (I) having active hydrogen include the following.
(1) Carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonyl hydrazide, benzophenone hydrazone, aminopolyacrylamide Hydrazide compounds such as;
(2) pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole;

 (3) 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino -3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6- Triazole compounds such as methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine;

(4) tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole;
(5) thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole;
(6) Maleic hydrazide, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone, etc. Pyridazine compounds;
Of these, pyrazole compounds and triazole compounds having a 5-membered or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly suitable.
These hydrazine derivatives can be used individually by 1 type or in mixture of 2 or more types.

Typical examples of the amine compound having active hydrogen that can be used as a part of the active hydrogen-containing compound (H) include the following.
(1) A primary amino group of an amine compound containing one secondary amino group and one or more primary amino groups, such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, and methylaminopropylamine, A compound modified with aldimine, ketimine, oxazoline or imidazoline by heat reaction with aldehyde or carboxylic acid at a temperature of about 100 to 230 ° C., for example;

(2) Secondary monoamines such as diethylamine, diethanolamine, di-n- or -iso-propanolamine, N-methylethanolamine, N-ethylethanolamine;
(3) a secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and a dialkyl (meth) acrylamide by a Michael addition reaction;
(4) A compound obtained by modifying a primary amino group of an alkanolamine such as monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 '(aminopropoxy) ethyl ether to ketimine;

The quaternary chlorinating agent that can be used as a part of the active hydrogen-containing compound (H) is a hydrazine derivative or a tertiary amine that does not have active hydrogen and is not reactive with an epoxy group by itself. In order to be able to react with the acid. The quaternary chlorinating agent reacts with an epoxy group in the presence of water as necessary to form a quaternary salt with the epoxy group-containing resin.
The acid used to obtain the quaternary chlorinating agent may be any of organic acids such as acetic acid and lactic acid, and inorganic acids such as hydrochloric acid. Examples of the hydrazine derivative having no active hydrogen used for obtaining a quaternary chlorinating agent include 3,6-dichloropyridazine, and examples of the tertiary amine include dimethylethanolamine, triethylamine, Examples include trimethylamine, triisopropylamine, and methyldiethanolamine.

The reaction product of the high molecular weight epoxy group-containing resin (E) and the active hydrogen-containing compound (H) composed of a hydrazine derivative (I) in which some or all of the compounds have active hydrogen is a high molecular weight epoxy group-containing resin (E ) And the active hydrogen-containing compound (H) at 10 to 300 ° C., preferably 50 to 150 ° C., for about 1 to 8 hours.
This reaction may be performed by adding an organic solvent, and the type of the organic solvent to be used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether , Propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and other alcohols and ethers containing hydroxyl groups; ethyl acetate, butyl acetate, ethylene glycol monobutyl ether acetate and other esters; toluene, xylene Aromatic hydrocarbons etc. Illustration can, it is possible to use one or more of these. Of these, ketone-based or ether-based solvents are particularly preferred from the standpoints of solubility with an epoxy resin and film-forming properties.

The blending ratio of the high molecular weight epoxy group-containing resin (E) and the active hydrogen-containing compound (H) composed of a hydrazine derivative (I) in which some or all of the compounds have active hydrogen is a solid content ratio of the high molecular weight epoxy group. The active hydrogen-containing compound (H) is preferably 0.5 to 20 parts by mass, particularly preferably 1.0 to 10 parts by mass with respect to 100 parts by mass of the containing resin (E).
The blending ratio of the high molecular weight epoxy group-containing resin (E) and the active hydrogen-containing compound (H) is the number of active hydrogen groups in the active hydrogen-containing compound (H) and the epoxy of the high molecular weight epoxy group-containing resin (E). It is appropriate from the viewpoint of corrosion resistance and the like that the ratio [number of active hydrogen groups / epoxy groups] to the number of groups is 0.01 to 10, more preferably 0.1 to 8, and still more preferably 0.2 to 4. .

  The proportion of the hydrazine derivative (I) having active hydrogen in the active hydrogen-containing compound (H) is 10 to 100 mol%, more preferably 30 to 100 mol%, and still more preferably 40 to 100 mol%. Is appropriate. If the ratio of the hydrazine derivative (I) having active hydrogen is less than 10 mol%, the upper layer film cannot be provided with a sufficient rust prevention function, and the resulting rust prevention effect is simply mixing the film-forming organic resin and the hydrazine derivative. It is no different from the case of using it.

The coating composition for an upper film of the present invention contains a high molecular weight epoxy group-containing resin (E) as an essential component, and a curing agent capable of reacting with a hydroxyl group in the high molecular weight epoxy group-containing resin. By containing, the film is crosslinked at the time of heating and drying after coating, and a film having a dense barrier property with better workability can be formed. As a curing method for forming a resin composition film, a curing method using a urethanization reaction between a polyisocyanate compound (G) and a hydroxyl group in an epoxy group-containing resin, an amino resin (F) and an epoxy group-containing resin A curing method using an etherification reaction with a hydroxyl group can be mentioned as a preferable one.
Examples of the amino resin (F) include methylol obtained by reaction of an amino component such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide with an aldehyde component such as formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. An amino acid resin is mentioned. Those obtained by etherifying the methylol group of this methylolated amino resin with a lower alcohol having 1 to 6 carbon atoms are also included in the amino resin.

Further, among the amino resins, a part or all of the methylol group of the methylol melamine resin is a methyl etherified melamine resin etherified with methyl alcohol, a butyl etherified melamine resin butyl etherified with butyl alcohol, or methyl alcohol. Particularly preferred is a mixed etherified melamine resin of methyl ether and butyl ether etherified with both of butyl alcohol. Also, among these, by using a methyl etherified melamine resin containing 1 or more, preferably 1.5 or more imino groups in one molecule, a low temperature with the high molecular weight epoxy group-containing resin (E). The reactivity is improved, and the toughness of the film can be greatly improved. Specific examples of commercially available products include, for example, Cymel 325, Cymel 327, Cymel 703 (all trade names) manufactured by Mitsui Cytec.
The above amino resins can be used individually by 1 type or in mixture of 2 or more types.

  Examples of the polyisocyanate compound (G) include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; cycloaliphatic diisocyanates such as hydrogenated xylylene diisocyanate and isophorone diisocyanate; Aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate; triphenylmethane-4,4 ', 4 "-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-tri Organic polyisocyanates such as polyisocyanate compounds having three or more isocyanate groups, such as isocyanatotoluene and 4,4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate Itself, or an adduct of each of these organic polyisocyanates with a polyhydric alcohol, a low molecular weight polyester resin, water, or the like, or a cyclized polymer of each of the above organic polyisocyanates, and further an isocyanate biuret And so on.

  Furthermore, among them, a polyisocyanate compound having 4 or more, particularly preferably 6 to 10 isocyanate groups in one molecule is a high-molecular-weight epoxy group-containing resin (E )), A tough film can be formed, and the corrosion resistance of the processed part when subjected to severe processing can be made particularly good. Examples of such a polyisocyanate compound include adducts of 4,4′-dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate, adducts of hexamethylene diisocyanate, and the like.

The polyisocyanate compound (G) may be obtained by blocking a part or all of the isocyanate groups of the polyisocyanate compound with a blocking agent. Examples of the blocking agent include phenols such as phenol, cresol and xylenol; Lactams such as caprolactam, δ-valerolactam, γ-butyrolactam, β-propiolactam; methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, ethylene glycol monoethyl Alcohols such as ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol; formamide Oximes such as shim, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime; active methylenes such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, methyl acetoacetate, etc. A blocking agent can be mentioned.
Specific examples of commercially available polyisocyanate compounds containing 4 or more isocyanate groups in one molecule include, for example, MF-B80M, MF-B60X, MF-K60X, ME20-B80S (all products) Name).

As content of the said hardening | curing agent in the coating composition for upper layer membrane | film | coats, it is 1-50 mass parts by the ratio of solid content with respect to solid content of 100 mass parts of high molecular weight epoxy group containing resin (E), Preferably it is 5-5 mass parts. 30 parts by mass is suitable from the viewpoint of curability.
The high molecular weight epoxy group-containing resin (E) is sufficiently cross-linked by the addition of the cross-linking agent (curing agent) as described above. However, in order to further increase the low-temperature cross-linking property, a known curing accelerating catalyst may be used. desirable. Examples of the curing accelerating catalyst include N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, and bismuth nitrate.
For the purpose of slightly improving physical properties such as adhesion, a known resin such as acrylic, alkyd, or polyester can be mixed with the high molecular weight epoxy group-containing resin (E).

The upper layer film (coating composition for the upper layer film) of the present invention may contain a non-chromium rust preventive additive as needed for the purpose of improving the corrosion resistance. By including such a non-chromium-based anticorrosive additive in the upper layer film, more excellent anticorrosion performance can be obtained.
As the non-chromium rust preventive additive, it is particularly preferable to use one or more selected from the following (e1) to (e7).
(E1) silicon oxide (e2) calcium or / and calcium compound (e3) poorly soluble phosphate compound (e4) molybdate compound (e5) selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms (e6) Vanadium compounds (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Organic compounds to be contained The details and anticorrosion mechanism of the non-chromium-based anticorrosive additives (e1) to (e7) are as described above for the surface treatment film.

The compounding amount of the non-chromium rust preventive additive is 0.1 to 50 parts by mass, preferably 0.5 to 30 in terms of the solid content with respect to 100 parts by mass of the resin solid content of the coating composition for film formation. The mass part is appropriate. If the blending amount of this non-chromium rust preventive additive is less than 0.1 parts by mass, the effect of improving the corrosion resistance after alkali degreasing cannot be sufficiently obtained. This is not preferable because not only the properties are lowered but also the corrosion resistance is lowered.
Two or more rust preventive additives (e1) to (e7) may be added in combination. In this case, since the inherent anticorrosive action is combined, higher corrosion resistance can be obtained. In particular, calcium ion-exchanged silica is used as the component (e1), and one or more of the components (e3) to (e5), particularly preferably all of the components (e3) to (e5) are added to this. In particular, excellent corrosion resistance can be obtained.

  In addition to the above rust preventive additive components, other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, etc.) may be used as the corrosion inhibitor in the upper layer coating (upper layer coating composition). Antimony oxide, etc.), phosphomolybdate (eg, aluminum phosphomolybdate), organic phosphoric acid and its salts (eg, phytic acid, phytate, phosphonic acid, phosphonate, and metal salts thereof, alkali metals) 1 type, or 2 or more types, such as a salt, an alkaline-earth metal salt, etc.) and organic inhibitors (for example, a hydrazine derivative, a thiol compound, a dithiocarbamate etc.) can be added.

In the upper layer coating (upper layer coating composition), if necessary, a solid lubricant can be blended for the purpose of improving the processability of the coating.
Examples of the solid lubricant applicable to the present invention include the following, and one or more of these can be used.
(1) Polyolefin wax, paraffin wax: For example, polyethylene wax, synthetic paraffin, natural paraffin, micro wax, chlorinated hydrocarbon, etc.
(2) Fluororesin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.), polyvinyl fluoride resin, polyvinylidene fluoride resin, etc. In addition, fatty acid amide compounds (eg, stearamide) , Palmitic acid amide, methylene bis stearoamide, ethylene bis stearoamide, oleic acid amide, esylic acid amide, alkylene bis fatty acid amide, etc.), metal soaps (eg, calcium stearate, lead stearate, calcium laurate, palmitic acid) Calcium, etc.), metal sulfide (eg, molybdenum disulfide, tungsten disulfide, etc.), graphite, fluorinated graphite, boron nitride, polyalkylene glycol, alkali metal sulfate, or the like may be used. .

Among the above solid lubricants, polyethylene wax and fluororesin fine particles (in particular, polytetrafluoroethylene resin fine particles) are preferable.
Examples of polyethylene waxes include Hoechst's Selidust 9615A, Selidust 3715, Selidust 3620, Selidust 3910 (all trade names), Sanyo Kasei Sun Wax 131-P, Sun Wax 161-P (all trade names) ), Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-800, Chemipearl W-950 (all trade names) manufactured by Mitsui Petrochemical Co., Ltd. can be used.

The fluororesin fine particles are most preferably tetrafluoroethylene fine particles. For example, Lubron L-2 and Lubron L-5 (both trade names) manufactured by Daikin Industries, Ltd., MP1100 and MP1200 manufactured by Mitsui / DuPont (all Are also trade names), full-on dispersion AD1, full-on dispersion AD2, full-on L141J, full-on L150J, and full-on L155J (all trade names) manufactured by Asahi IC Fluoropolymers.
Among these, a particularly excellent lubricating effect can be expected by the combined use of polyolefin wax and tetrafluoroethylene fine particles.
The blending amount of the solid lubricant in the upper layer film is 1 to 30 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the resin solid content of the coating composition for film formation. To do. If the blending amount of the solid lubricant is less than 1 part by mass, the lubricating effect is poor. On the other hand, if the blending amount exceeds 30 parts by mass, the paintability is lowered, which is not preferable.

  The upper film (coating composition for the upper film) of the surface-treated steel sheet of the present invention has a high molecular weight epoxy group-containing resin (E) as an essential component, and if necessary, a curing agent and a non-chromium rust preventive additive. Solid lubricants and the like are added, and if necessary, organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments), coloring dyes (for example, organic solvent-soluble azo compounds) Dyes, water-soluble azo metal dyes, etc.), inorganic pigments (eg, titanium oxide), chelating agents (eg, thiols), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, etc.), iron phosphide , Antimony-doped tin oxide, etc.), coupling agent (for example, silane coupling agent, titanium coupling agent, etc.), melamine / cyanuric acid adduct, etc. It can be added on.

Moreover, the coating composition for film formation containing the said main component and an additional component normally contains a solvent (an organic solvent and / or water), and also a neutralizer etc. are added as needed.
The organic solvent is not particularly limited as long as it can dissolve or disperse the high molecular weight epoxy group-containing resin (E) and can be prepared as a coating composition. For example, various organic solvents exemplified above are used. be able to.
The neutralizing agent is blended as necessary to neutralize the high molecular weight epoxy group-containing resin (E) to make it water-based, and the high molecular weight epoxy group-containing resin (E) is a cationic resin. In some cases, acids such as acetic acid, lactic acid and formic acid can be used as neutralizing agents.

The dry film thickness of the upper layer film is 0.3 to 2.0 μm, preferably 0.4 to 1.5 μm. When the film thickness of the upper layer film is less than 0.3 μm, the corrosion resistance is insufficient. On the other hand, when the film thickness exceeds 2.0 μm, the weldability and the electrodeposition coating property are deteriorated.
Further, from the viewpoint of weldability and electrodeposition coating properties, the total film thickness of the surface treatment film of the first layer and the upper film of the second layer is preferably 2.0 μm or less.

Next, the manufacturing method of the surface treatment steel plate of this invention is demonstrated.
In order to form the surface treatment film on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, the surface treatment composition (treatment liquid) having the above-described composition is applied to the surface of the plated steel sheet so that the dry film thickness is in the above range. Apply and heat dry without rinsing.
As a method for forming the surface treatment composition on the surface of the plated steel sheet, any of a coating method, a dipping method, and a spray method may be used. As a coating treatment method, any method such as a roll coater (3-roll method, 2-roll method, etc.), a squeeze coater, or a die coater may be used. In addition, after the coating process or dipping process using a squeeze coater or the like, or the spray process, the coating amount can be adjusted, the appearance can be made uniform, and the film thickness can be made uniform by an air knife method or a roll drawing method.

After coating the surface treatment composition, it is dried by heating without washing with water. As the heating and drying means, a dryer, a hot air furnace, a high frequency induction heating furnace, an infrared furnace or the like can be used. Heat drying is preferably performed in the range of 30 to 150 ° C., preferably 40 to 140 ° C., at the ultimate plate temperature. If the heating and drying temperature is less than 30 ° C., a large amount of moisture remains in the film, resulting in insufficient corrosion resistance. Further, when the heating and drying temperature exceeds 150 ° C., not only is it uneconomical, but also defects occur in the film, resulting in a decrease in corrosion resistance. Moreover, since it becomes impossible to apply to a BH steel plate when heat drying temperature exceeds 150 degreeC, it is unpreferable.
An upper layer film (organic resin film) is formed as the second layer film on the upper layer of the surface treatment film formed as described above. The coating composition for the second layer film is applied to the surface-treated film surface so as to have the above-described film thickness, and dried by heating. Application | coating of a coating composition should just be performed according to the method used for formation of the surface treatment film mentioned above.

  After application of the coating composition, drying is usually performed without washing with water, but a washing process may be performed after application of the coating composition. For the heat drying treatment, a dryer, a hot air furnace, a high-frequency induction heating furnace, an infrared furnace, or the like can be used. Heat drying is preferably performed in the range of 30 to 150 ° C., preferably 40 to 140 ° C., at the ultimate plate temperature. If the heating and drying temperature is less than 30 ° C., a large amount of moisture remains in the film, resulting in insufficient corrosion resistance. In addition, when the heating and drying temperature exceeds 150 ° C., not only is it uneconomical, but defects occur in the film and the corrosion resistance decreases. Moreover, since it becomes impossible to apply to a BH steel plate when heat drying temperature exceeds 150 degreeC, it is not preferable.

Therefore, the manufacturing method of the surface treatment steel plate of this invention and its preferable embodiment are as follows.
[1] A surface treatment composition containing the following components (a) to (d) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified A resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with an active hydrogen-containing compound comprising a hydrazine derivative (C) in which some or all of the compounds have active hydrogen is used in water. Dispersed aqueous epoxy resin dispersion (b) Silane coupling agent: 1 to 300 parts by mass of solid content with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion (c) phosphoric acid and / or Or phosphoric acid compound: based on 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion 0.1 to 80 parts by mass in terms of the form fraction (d) Compound containing 1 to 5 fluorine atoms in one molecule: in terms of solid content with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion 0.1 to 100 parts by mass An upper layer coating composition containing a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 is applied to the upper layer, and the ultimate plate temperature is 30 to 150 ° C. A method for producing a highly corrosion-resistant surface-treated steel sheet, characterized by forming an upper film having a film thickness of 0.3 to 2.0 µm by drying at a temperature.

[2] In the production method of [1], the surface treatment composition for forming a surface treatment film further comprises a non-chromium rust preventive additive, and a resin solid content of the aqueous epoxy resin dispersion of component (a) of 100 mass. The manufacturing method of the highly corrosion-resistant surface treatment steel plate characterized by containing 0.1-50 mass parts with the ratio of solid content with respect to a part.
[3] In the production method of [1] or [2] above, the coating composition for forming an upper layer film further contains a non-chromium rust preventive additive with a solid content of 100 parts by mass of resin solid content of the coating composition. The manufacturing method of the highly corrosion-resistant surface treatment steel plate characterized by containing 0.1-50 mass parts in ratio.
[4] In the production method according to any one of [1] to [3] above, the surface treatment composition for forming a surface treatment film and / or the coating composition for forming an upper layer film is a non-chromium rust preventive additive, The manufacturing method of the highly corrosion-resistant surface treatment steel plate characterized by including 1 or more types chosen from following (e1)-(e7).
(E1) Silicon oxide (e2) Calcium and / or calcium compound (e3) Slightly soluble phosphate compound (e4) Molybdate compound (e5) Selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms (e6) Vanadium compounds (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds

[5] In the production method according to any one of [1] to [4], the upper layer coating composition further includes a curing agent having a group that crosslinks with a hydroxyl group, as a solid of the high molecular weight epoxy group-containing resin (E). 1-50 mass parts is contained in the ratio of solid content with respect to 100 mass parts per minute, The manufacturing method of the highly corrosion-resistant surface-treated steel plate characterized by the above-mentioned.
[6] The highly corrosion-resistant surface in which the curing agent having a group capable of crosslinking with a hydroxyl group is an amino resin (F) having an average of one or more imino groups in one molecule in the production method of [5] above A method for producing a treated steel sheet.
[7] The high corrosion resistance characterized in that, in the production method of [5], the curing agent having a group capable of crosslinking with a hydroxyl group is a polyisocyanate compound (G) having an average of 4 or more isocyanate groups in one molecule. Manufacturing method of surface-treated steel sheet.
[8] A highly corrosion-resistant surface-treated steel sheet characterized in that, in the production method of [7], the polyisocyanate compound (G) is obtained by blocking at least a part of isocyanate groups of the polyisocyanate compound with a blocking agent. Manufacturing method.

[9] In the production method according to any one of [1] to [8], the high molecular weight epoxy group-containing resin (E) in the coating composition for an upper layer film is a hydrazine in which some or all of the compounds have active hydrogen. A method for producing a highly corrosion-resistant surface-treated steel sheet, which is a modified epoxy group-containing resin modified with an active hydrogen-containing compound (H) comprising a derivative (I).
[10] In the production method according to any one of [1] to [9] above, the coating composition for forming an upper film further includes a solid lubricant with a solid content with respect to 100 parts by mass of the resin solid content of the coating composition. The manufacturing method of the highly corrosion-resistant surface treatment steel plate characterized by containing 1-30 mass parts in a ratio.
In addition, the surface treatment film and the upper layer film described above may be formed on either one side or both sides of the plated steel sheet. Examples of combinations of the film forms on the front and back surfaces of the plated steel sheet include, for example, surface treatment film + upper layer film / no treatment. , Surface treatment film + upper layer film / surface treatment film, surface treatment film + upper layer film / surface treatment film + upper layer film, and the like.

  The surface treatment composition for forming the first layer uses a water-soluble or water-dispersible epoxy resin shown in Table 2 as a resin composition, and a silane coupling agent (Table 3), phosphoric acid or a phosphoric acid compound (Table) 4) A compound containing 1 to 5 fluorine atoms in one molecule (Table 5) and a non-chromium rust preventive additive (Table 6) are appropriately blended, and a predetermined time using a paint disperser (sand grinder). The surface treatment composition was prepared by stirring.

Water-soluble or water-dispersible epoxy resins shown in Table 2 were produced as follows.
-Production of polyalkylene glycol-modified epoxy resin <Production Example 1>
To a glass four-necked flask equipped with a thermometer, stirrer and condenser, 1688 g of polyethylene glycol having a number average molecular weight of 4000 and 539 g of methyl ethyl ketone were added and stirred and mixed at 60 ° C., and then 171 g of tolylene diisocyanate was added. In addition, after reacting for 2 hours, Epicote 834X90 (epoxy resin, manufactured by Shell Japan, epoxy equivalent 250) 1121 g, 66 g of diethyleneglycolethyl ether and 1.1 g of 1% dibutyltin dilaurate solution were added, and further reacted for 2 hours. I let you. Thereafter, the temperature was raised to 80 ° C. and reacted for 3 hours to confirm that the isocyanate value was 0.6 or less. Thereafter, the temperature was raised to 90 ° C., and methyl ethyl ketone was removed by distillation under reduced pressure until the solid content concentration reached 81.7%. After removal, 659 g of propylene glycol monomethyl ether and 270 g of deionized water were added and diluted to obtain a polyalkylene glycol-modified epoxy resin solution A1 having a solid concentration of 76%.

・ Production of aqueous epoxy resin dispersion <Production Example 2>
2029 g of EP1004 (epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 1000) and 697 g of propylene glycol monobutyl ether were charged into a four-necked flask, heated to 110 ° C. and completely dissolved in 1 hour. After 1180 g of the polyalkylene glycol-modified epoxy resin solution A1 obtained in Production Example 1 and 311.7 g of 3-amino-1,2,4-triazole (molecular weight 84) were added to this product and reacted at 100 ° C. for 5 hours. Then, 719.6 g of propylene glycol monobutyl ether was added to obtain a resin solution D1.
257.6 g of the above resin solution D1 was mixed with 50 g of MF-K60X (isocyanate curing agent, manufactured by Asahi Kasei Kogyo Co., Ltd.) and 0.3 g of Scat24 (curing catalyst), and after stirring well, 692.1 g of water was added dropwise little by little. Mixing and stirring were performed to obtain an aqueous epoxy resin dispersion E1.

<Production Example 3> (Aqueous epoxy resin dispersion containing no hydrazine derivative)
2029 g of EP1004 (epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 1000) and 697 g of propylene glycol monobutyl ether were charged into a four-necked flask, heated to 110 ° C. and completely dissolved in 1 hour. 1180 g of the polyalkylene glycol-modified epoxy resin solution A1 obtained in Production Example 1 and 527.0 g of propylene glycol monobutyl ether were added to this to obtain a resin solution D2.
To 257.6 g of the above resin solution D2, 50 g of MF-K60X (isocyanate curing agent, manufactured by Asahi Kasei Kogyo Co., Ltd.) and 0.3 g of Scat24 (curing catalyst) were mixed and stirred well, and then 692.1 g of water was dropped and mixed little by little. The mixture was stirred to obtain an aqueous epoxy resin dispersion E2.

As the coating composition for forming the second layer, the resin compositions shown in Table 7 and Table 8 are used, and a non-chromium rust preventive additive (Table 6) and a solid lubricant (Table 9) are appropriately blended therein. Then, the mixture was stirred for a predetermined time using a paint disperser (sand grinder) to prepare a paint composition.
The base resins (reaction products) of the resin compositions shown in Table 7 and Table 8 were synthesized as follows.
<Synthesis Example 1>
Epicoat 828 (Japan Epoxy Resin, Epoxy Equivalent 187) 634 parts, bisphenol A 366 parts, 50% tetraethylammonium bromide aqueous solution 8 parts and cyclohexanone 180 parts were charged into a four-necked flask, heated to 150 ° C. and reacted for 5 hours. After cooling, 300 parts of methyl isobutyl ketone and 1843 parts of cyclohexanone were added while cooling to obtain an epoxy resin solution F1 (resin composition (1)) having a solid content of 30%. The number average molecular weight of this resin was 7600.
<Synthesis Example 2>
347 parts of Epicoat 1256 (manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent 7880) and 543 parts of cyclohexanone were charged into a four-necked flask, heated to 130 ° C., and the epoxy resin was completely dissolved in 2 hours. This was cooled to 120 ° C., 3.7 parts of 3-amino-1,2,4-triazole (molecular weight 84) was added and reacted for 6 hours until the epoxy group disappeared. 78 parts of ketone and 197 parts of cyclohexanone were added to obtain a triazole-modified epoxy resin solution F2 (resin composition (2)) having a solid content of 30%. The number average molecular weight of this resin was 10100.

<Synthesis Example 3>
Epicoat 828 (Japan Epoxy Resin, Epoxy Equivalent 187) 637 parts, bisphenol A 363 parts, 50% tetraethylammonium bromide aqueous solution 10 parts and cyclohexanone 175 parts were charged into a four-necked flask, heated to 160 ° C. and reacted for 4 hours. To obtain an epoxy resin solution having a solid content of 85%. To this, 1315 parts of cyclohexanone was added and then cooled to 100 ° C., 9.7 parts of 3,5-dimethylpyrazole and 13 parts of dibutylamine were added and reacted for 6 hours until the epoxy group disappeared. While adding 908 parts of methyl isobutyl ketone, a 30% solid content pyrazole-modified epoxy resin solution F3 (resin composition (3)) was obtained. The number average molecular weight of this resin was 6300.
<Synthesis Example 4>
Epicoat 828 (manufactured by Japan Epoxy Resin Co., Epoxy Equivalent 187), 1833 parts, 894 parts of bisphenol A, 1.96 parts of tetraethylammonium bromide and 294 parts of methyl isobutyl ketone were charged into a four-necked flask and heated to 140 ° C. for 4 hours. While reacting, 3795 parts of ethylene glycol monobutyl ether was added while cooling to obtain an epoxy resin solution F4 (resin composition (4)) having an epoxy equivalent of 1388 and a solid content of 40%. The number average molecular weight of this resin was 3100.

The plated steel sheet shown in Table 1, which is a plated steel sheet for home appliances, building materials, and automobile parts based on cold-rolled steel sheets, was used as a processing original sheet. In addition, the thing of predetermined | prescribed board thickness was employ | adopted for the board thickness of the steel plate according to the objective of evaluation. After the surface of this plated steel sheet was subjected to alkali degreasing treatment, washed with water and dried, the surface treatment composition for forming the first layer was applied with a roll coater and dried by heating at various temperatures. The film thickness of the film was adjusted by the solid content (heating residue) of the surface treatment composition or coating conditions (rolling force of the roll, rotation speed, etc.).
Next, the coating composition for forming the second layer was applied by a roll coater and dried by heating at various temperatures. The film thickness of the film was adjusted by the solid content (heating residue) of the coating composition or application conditions (rolling force of roll, rotation speed, etc.).

Tables 10 to 23 show the results of evaluating the film composition and quality performance (corrosion resistance, post-processing corrosion resistance, weldability, electrodeposition coating property) of the obtained surface-treated steel sheet. The quality performance was evaluated as follows.
(1) Corrosion resistance Each sample was degreased at 60 ° C. for 2 minutes using “FC-4460” manufactured by Nihon Parkerizing Co., Ltd., and then subjected to the following combined cycle test (CCT), after 63 cycles. The white rust generation area ratio and the red rust generation area ratio were evaluated.
Salt spray (based on JIS Z 2371): 4 hours ↓
Dry (60 ° C): 2 hours ↓
Wet (50 ° C., 95% RH): 2 hours The evaluation criteria are as follows.
◎: White rust generation area ratio less than 5% ○ +: White rust generation area ratio of 5% or more and less than 10% ○: White rust generation area ratio of 10% or more and less than 30% ○-: White rust generation area ratio of 30% or more No red rust occurrence △: Red rust occurrence, red rust occurrence area ratio less than 10% ×: Red rust occurrence area ratio 10% or more

(2) Corrosion resistance after processing For each sample, deformation and sliding were added with a draw bead under the following conditions, and this sample was used at 60 ° C. for 2 minutes using “FC-4460” manufactured by Nihon Parkerizing Co., Ltd. After degreasing under the conditions, the CCT performed in “(1) Corrosion resistance” was performed, and the white rust generation area ratio and red rust generation area ratio after 36 cycles were evaluated.
Pressing load: 800kgf
Drawing speed: 1000mm / min
Bead shoulder R: Male side 2mmR, Female side 3mmR
Pushing depth: 7mm
Oil used: “Preton R-352L” manufactured by Sugimura Chemical Co., Ltd.
The evaluation criteria are as follows.
◎: White rust generation area ratio less than 5% ○ +: White rust generation area ratio of 5% or more and less than 10% ○: White rust generation area ratio of 10% or more and less than 30% ○-: White rust generation area ratio of 30% or more No red rust occurrence △: Red rust occurrence, red rust occurrence area ratio less than 10% ×: Red rust occurrence area ratio 10% or more

(3) Weldability With respect to each sample, a welding test with continuous spotting was performed under the conditions of using electrode: CF-type Cr—Cu electrode, applied pressure: 200 kgf, energizing time: 10 cycles / 50 Hz, welding current: 10 kA, and continuously hitting. The score was evaluated. The evaluation criteria are as follows.
◎: 2000 points or more ○: 1000 points or more, less than 2000 points △: 500 points or more, less than 1000 points ×: Less than 500 points (4) Electrodeposition paintability Cationic electrodeposition paint (manufactured by Kansai Paint Co., Ltd.) After coating “GT-10”) to a film thickness of 30 μm, baking was performed at 130 ° C. for 30 minutes. The coated sample was immersed in boiling water for 2 hours, immediately cut in a grid pattern (10 × 10, 1 mm interval), attached and peeled with an adhesive tape, and the peeled area ratio of the coating film was measured. The evaluation criteria are as follows.
◎: No peeling ○: Peeling area ratio less than 5% △: Peeling area ratio of 5% or more and less than 20% ×: Peeling area ratio of 20% or more

In addition, * 1 to * 10 described in Tables 10 to 23 indicate the following contents.
* 1: No. described in Table 1. (Plated steel plate)
* 2: No. in Table 2 (Water-soluble or water-dispersible epoxy resin)
* 3: No. described in Table 3 (Silane coupling agent)
* 4: No. in Table 4 (Phosphoric acid or phosphoric acid compound)
* 5: No. in Table 5 (Compound containing 1 to 5 fluorine atoms in one molecule)
* 6: No. in Table 6 (Anti-rust additive)
* 7: parts by mass (for components other than water-soluble or water-dispersible epoxy resins, parts by mass of the solid content relative to 100 parts by mass of the water-soluble or water-dispersible epoxy resin)
* 8: No. described in Table 7 and Table 8. (Resin composition)
* 9: No. in Table 9 (Solid lubricant)
* 10: parts by mass (for components other than organic resins, parts by mass of solid content relative to 100 parts by mass of organic resin solids)

Claims (11)

The film thickness formed by applying a surface treatment composition containing the following components (a) to (d) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and drying is 0.01 to 1.0 μm. Has a surface treatment film of
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified A resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with an active hydrogen-containing compound comprising a hydrazine derivative (C) in which some or all of the compounds have active hydrogen is used in water. Dispersed aqueous epoxy resin dispersion (b) Silane coupling agent: 1 to 300 parts by mass of solid content with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion (c) phosphoric acid and / or Or phosphoric acid compound: based on 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion 0.1 to 80 parts by weight in a ratio of solid content (d) trifluoride vanadium, one or more selected from among tetrafluoride vanadium solid the resin solid content 100 parts by weight of the aqueous epoxy resin dispersion 0.1 to 100 parts by weight in a proportion of minutes Formed by applying an upper layer coating composition containing a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 to the upper layer and drying. A highly corrosion-resistant surface-treated steel sheet, characterized in that it has an upper film having a coated film thickness of 0.3 to 2.0 μm.   The surface treatment composition for forming the surface treatment film further contains a non-chromium rust preventive additive in a solid content ratio of 0.1 to 100 parts by mass of the resin solid content of the aqueous epoxy resin dispersion of component (a). The highly corrosion-resistant surface-treated steel sheet according to claim 1, which contains ˜50 parts by mass.   The upper layer coating composition further comprises 0.1 to 50 parts by mass of a non-chromium anticorrosive additive in a solid content ratio of 100 parts by mass of the resin solid content of the coating composition. The highly corrosion-resistant surface-treated steel sheet according to claim 1 or 2. The surface treatment composition for forming the surface treatment film and / or the coating composition for the upper film contains at least one selected from the following (e1) to (e7) as a non-chromium rust preventive additive. The highly corrosion-resistant surface-treated steel sheet according to any one of claims 1 to 3.
(E1) silicon oxide (e2) calcium and / or calcium compound (e3) poorly soluble phosphate compound (e4) molybdate compound (e5) selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms (e6) Vanadium compounds (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds   The coating composition for the upper film further contains 1 to 50 parts by mass of a curing agent having a group that crosslinks with a hydroxyl group in a solid content ratio of 100 parts by mass of the solid content of the high molecular weight epoxy group-containing resin (E). The highly corrosion-resistant surface-treated steel sheet according to any one of claims 1 to 4.   6. The highly corrosion-resistant surface-treated steel sheet according to claim 5, wherein the curing agent having a group that crosslinks with a hydroxyl group is an amino resin (F) having an average of one or more imino groups in one molecule.   The highly corrosion-resistant surface-treated steel sheet according to claim 5, wherein the curing agent having a group that crosslinks with a hydroxyl group is a polyisocyanate compound (G) having an average of 4 or more isocyanate groups in one molecule.   The high-corrosion-resistant surface-treated steel sheet according to claim 7, wherein the polyisocyanate compound (G) is obtained by blocking at least a part of isocyanate groups of the polyisocyanate compound with a blocking agent.   The high molecular weight epoxy group-containing resin (E) is a modified epoxy group-containing resin modified with an active hydrogen-containing compound (H) comprising a hydrazine derivative (I) in which some or all of the compounds have active hydrogen. The highly corrosion-resistant surface-treated steel sheet according to any one of claims 1 to 8.   The coating composition for an upper layer film further contains 1 to 30 parts by mass of a solid lubricant in a ratio of a solid content with respect to 100 parts by mass of a resin solid content of the coating composition. The high corrosion resistance surface-treated steel sheet according to any one of the above. The coating thickness is obtained by applying a surface treatment composition containing the following components (a) to (d) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and drying at a temperature of a reached plate temperature of 30 to 150 ° C. Forms a surface treatment film of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified A resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with an active hydrogen-containing compound comprising a hydrazine derivative (C) in which some or all of the compounds have active hydrogen is used in water. Dispersed aqueous epoxy resin dispersion (b) Silane coupling agent: 1 to 300 parts by mass of solid content with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion (c) phosphoric acid and / or Or phosphoric acid compound: based on 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion 0.1 to 80 parts by weight in a ratio of solid content (d) trifluoride vanadium, one or more selected from among tetrafluoride vanadium solid the resin solid content 100 parts by weight of the aqueous epoxy resin dispersion 0.1 to 100 parts by mass in the proportion of minutes The upper layer coating composition containing a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 is applied to the upper layer, and the ultimate plate temperature is 30 A method for producing a highly corrosion-resistant surface-treated steel sheet, wherein an upper layer film having a film thickness of 0.3 to 2.0 μm is formed by drying at a temperature of ˜150 ° C.