JP2005325427A - Weldable surface-treated steel sheet with high corrosion resistance for automobile, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-treated steel sheet with a film having superior corrosion resistance though containing no chromium. <P>SOLUTION: This weldable surface-treated steel sheet comprises: a zinc-plated steel sheet or the like; a surface treatment film formed on the surface of the sheet by use of a surface treatment composition including (a) a water-based dispersion of an epoxy resin that is obtained by reacting a modified epoxy resin of a polyalkylene glycol, which is obtained by reacting the polyalkylene glycol having a specific molecular weight, with a bisphenol epoxy resin, a compound containing active hydrogen and a polyisocyanate compound, a resin containing an epoxy functional group and a resin obtained by reacting hydrazine having active hydrogen, (b) a silane coupling agent and (c) phosphoric acid and/or hexafluoro metallic acid; and an upper layer film formed thereon including a high-molecular-weight resin containing the epoxy functional group with a number average molecular weight of 6,000 to 20,000, a chromium-free rust-preventive additive, a solid lubricant with a molecular weight of 5,000 or less and an electroconductive pigment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface-treated steel sheet for automobiles used for automobile parts and automobile bodies (including replacement repair parts). For example, (1) omission of chemical conversion treatment process and (2) chemical conversion treatment in an automobile manufacturer. Providing organic coated steel sheets aimed at eliminating processes and electrodeposition coating processes, (3) reducing electrodeposition film thickness in electrodeposition coating processes, and (4) omitting or reducing auxiliary materials (sealers, waxes), etc. To do.

  Conventionally, in the field of building materials, painted steel plates such as colored zinc iron plates and colored steel plates have been used for roofing materials and wall materials. In the consumer electronics industry, where strict performance is required for product design, it was triggered by the adoption of pre-coated steel sheets (PCM) in refrigerators by US consumer electronics manufacturers. Pre-coated steel sheet is applied. Pre-coating is a method in which the surface of a steel plate (strip) is coated in advance by a method such as roll coating or powder coating, and processing and assembly are performed using this coated steel plate. For the method of painting after processing, the benefits of cost reduction and environmental measures can be expected by omitting the pretreatment and painting process by the user.

On the other hand, in the field of automobiles, corrosion of automobile bodies due to road freezing prevention salts sprayed in winter in cold regions such as North America and Northern Europe has become a major social problem, and rust prevention measures for the automobile bodies have been strengthened.
Conventionally, as a rust-proof steel plate for automobiles, a rust-proof coated steel plate (zinc metal) having a zinc powder-containing coating film formed with a film thickness of 10 to 20 μm, such as Patent Document 1, has been used. However, the coating film containing zinc powder of this rust-prevention coated steel sheet shows significant peeling of the film during press molding, which not only causes accumulation of defects and press cracks in the mold, but also the part where the rust-proof coating peels off. There was a problem that the corrosion resistance of the deteriorated.

  In recent years, it can be said that the need for rust prevention is almost satisfied by the remarkable progress of quality performance such as rust prevention and workability of galvanized steel sheet. On the other hand, recently, in manufacturing processes at automakers, there is a need to reduce total costs by reducing and omitting secondary materials such as sealers and waxes, reducing film thickness of electrodeposition coating, shortening and omitting chemical conversion treatment and electrodeposition processes. Is growing. European automakers have already formed a chromate film on the surface of galvanized steel sheets with the aim of reducing and omitting secondary materials such as sealers and waxes, and further containing conductive metal powders such as zinc powder. There are cases in which an organic coated steel sheet having a coating film of a certain degree is employed. However, the fact that it is necessary to perform a chromate treatment containing hexavalent chromium, the problem of peeling of the film during press working, and the problem of corrosion resistance after peeling is not actually solved.

  Recently, as rust-proof steel plates applied to automobiles and the like, for example, those shown in Patent Documents 2 to 5 have been proposed, and Patent Document 6 discloses phosphoric acid on the surface of a zinc-based alloy-plated steel sheet. A rust-proof steel sheet is shown in which a chemical conversion treatment mainly composed of a compound is performed and an organic coating film composed of an organic resin, a conductive pigment and a rust-proof pigment is formed on the surface thereof.

Japanese Patent Publication No. 47-6882 Japanese Patent Laid-Open No. 10-44307 Japanese Patent Laid-Open No. 9-276785 Japanese Patent Laid-Open No. 10-043677 JP-A-10-128906 JP-A-9-277438

However, since the rust-proof steel sheets of Patent Documents 2 to 5 are all subjected to chromate treatment or use hexavalent chromium-based rust-proof pigments, there are problems in terms of the environment. In addition, since the rust-proof steel sheet of Patent Document 6 has been subjected to a conventional crystalline phosphate treatment as a chemical conversion treatment, not only processability cannot be expected, but also a hexavalent chromic acid type as a rust-proof pigment. The use of anti-corrosive pigments also has environmental problems.
Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a surface-treated steel sheet for automobiles that exhibits excellent corrosion resistance without containing chromium in the film, and also has excellent weldability and workability. It is to provide.

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 acts to suppress 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. Realization in the coating, specifically, the barrier layer (a) (organic resin matrix layer described later) above the coating, and the reaction layer (b) (amorphous compound layer described below) below the coating. ), And more preferably, by depositing a substance that causes a self-repairing action in the film, it has been found that these synergistic effects can improve the corrosion resistance. 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 specific modified epoxy resin with a hydrazine derivative having active hydrogen and the like in a water-dispersible liquid of a resin. It can be obtained by applying a surface treatment composition containing a hexafluorometal acid or the like to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and drying it.
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 it is possible to 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 to 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.

  Further, by adding a water-soluble phosphate or a non-chromium rust preventive additive to the surface treatment composition, further excellent corrosion resistance can be obtained. In the same way as above, the poorly soluble film exhibits a barrier against corrosion factors, and the phosphate component captures the eluted plating metal ions, forming an insoluble compound with the plating metal ions. It is possible to do. Further, since the non-chromium rust preventive additive forms a protective film at the starting point of corrosion, further excellent anticorrosive performance can be obtained. In practice, these combined effects provide very good anticorrosion performance.

  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 by a wrinkle presser bead or the like in a press die for automobiles, the processed portion is greatly damaged and its corrosion resistance is 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 by using this resin as a main component resin, and forming a film in which a non-chromium-based antirust additive and a specific solid lubricant are blended. It has been found that a high degree of anticorrosive effect can be obtained even in the part subjected to the above severe processing and alkali degreasing. 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 based on such findings, and the features thereof are as follows.
[1] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and the film thickness formed by drying 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 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water (b) Silane Coupling agent: 1 to 300 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
In the upper layer, a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000, a non-chromium rust preventive additive, a solid lubricant composed of an organic substance having a molecular weight of 5000 or less, and a conductive pigment It is a film formed by applying and drying the organic inorganic composition for the upper layer, and it is a non-chromium rust preventive additive with respect to 100 parts by mass of the solid content of the high molecular weight epoxy group-containing resin (E) 0.1 to 120 parts by mass (solid content), 0.1 to 30 parts by mass (solid content) of a solid lubricant, and 5% by volume ratio in the total film solid content of the upper film. A high corrosion-resistant surface-treated steel sheet for automobiles that can be welded, characterized in that it has an upper film with a film thickness of 1 to 30 μm and containing 70% by volume.

[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 weldable high corrosion-resistant surface-treated steel sheet for automobiles, containing 0.1 to 50 parts by mass (solid content) with respect to parts by mass.
[3] In the surface-treated steel sheet according to [1] or [2], the surface treatment composition for forming a surface treatment film further contains a conductive pigment, and the total solid content of the surface treatment film of the conductive pigment A weldable high corrosion-resistant surface-treated steel sheet for automobiles, characterized in that the volume ratio is 5 to 70% by volume.
[4] In the surface-treated steel sheet according to any one of [1] to [3], the conductive pigment is one or more selected from metals, alloys, conductive carbon, iron phosphide, carbides, and semiconductor oxides. A highly corrosion-resistant surface-treated steel sheet for automobiles that is weldable.

[5] In the surface-treated steel sheet according to any one of [1] to [4], the non-chromium anticorrosive additive contains one or more selected from the following (e1) to (e7): Highly corrosion-resistant surface-treated steel sheet for automobiles that can be welded.
(E1) Silicon oxide (e2) Calcium and / or calcium compound (e3) Slightly soluble phosphate compound (e4) Molybdate compound (e5) Vanadium compound (e6) Triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atom selected from (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds
[6] In the surface-treated steel sheet according to any one of [1] to [5], the organic inorganic composition for the upper layer further contains a curing agent having a group that crosslinks with a hydroxyl group of the high molecular weight epoxy group-containing resin (E). 1 to 50 parts by mass (solid content) with respect to 100 parts by mass of solid content, a weldable high corrosion resistance surface-treated steel sheet for automobiles.

[7] The surface-treated steel sheet according to [6], wherein the curing agent having a group that crosslinks with a hydroxyl group is an amino resin (F) having an average of at least one imino group in one molecule. A highly corrosion-resistant surface-treated steel sheet for automobiles.
[8] In the surface-treated steel sheet according to [6], 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. Highly corrosion-resistant surface-treated steel sheet for automobiles.
[9] The weldable automobile according to [8], wherein the polyisocyanate compound (G) is obtained by blocking at least a part of isocyanate groups of the polyisocyanate compound with a blocking agent. High corrosion resistance surface-treated steel sheet.
[10] In the surface-treated steel sheet according to any one of [1] to [9] above, the high molecular weight epoxy group-containing resin (E) in the upper layer organic-inorganic composition has some or all of the compounds having active hydrogen. A weldable, highly corrosion-resistant surface-treated steel sheet for automobiles, which is a modified epoxy group-containing resin modified with an active hydrogen-containing compound (H) comprising a hydrazine derivative (I).

[11] A surface treatment composition containing the following components (a) to (c) 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 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water (b) Silane Coupling agent: 1 to 300 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
On the upper layer, 0.1 to 120 parts by mass (solid content) of a non-chromium rust preventive additive with respect to 100 parts by mass of the high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 And 0.1-30 parts by mass (solid content) of a solid lubricant composed of an organic substance having a molecular weight of 5000 or less, and the volume ratio in the total solid content of the upper film is 5 to 70% by volume. An upper layer organic inorganic composition containing an amount of a conductive pigment is applied, and an upper layer film having a film thickness of 1 to 30 μm is formed by drying at an ultimate plate temperature of 30 to 150 ° C. A method for producing weldable high corrosion-resistant surface-treated steel sheets for automobiles.

  The surface-treated steel sheet for automobiles of the present invention has a very excellent flat plate and post-processing corrosion resistance despite containing no chromium in the film, and is also excellent in workability, weldability and paintability.

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 a galvanized steel sheet, a Zn-Ni alloy-plated steel sheet, a 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-plated steel plate (for example, Zn-6% Al-3% Mg alloy) Plated steel sheet, Zn-11% Al-3% Mg alloy-plated steel sheet), and further, metal oxides, polymers, etc. were dispersed in the plating film of these plated steel sheets Lead-based composite plated steel sheets (for example, Zn-SiO ₂ dispersion plating steel plate) or 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 the above-described various plating may be performed thereon.
As a plating method, any feasible method among an electrolytic method (electrolysis in an aqueous solution or electrolysis in a nonaqueous solvent), a melting method, and a gas phase method can be adopted.
Furthermore, in order to prevent the 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 or acid solution containing Ni, Co, Fe on the surface of the plating film. 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 (c) and dried. It is the surface treatment film formed by this. This surface treatment film does not contain any chromium.
(A) Polyalkylene glycol-modified epoxy resin (A) 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, 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. An aqueous epoxy resin dispersion obtained by dispersing the resin obtained by the reaction in water (b) Silane coupling agent: 1 to 300 parts by mass (solid) with respect to 100 parts by mass of the resin solid content of the aqueous epoxy resin dispersion Min)
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion

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 the water dispersibility and storability 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.

Representative 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′-dihydroxydiphenyl sulfone, 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 compounds, bisphenol A type epoxy resins are particularly suitable in that a film excellent in flexibility and anticorrosion properties 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 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, as long as it has an epoxy group and a polymerizable unsaturated group, such as glycidyl methacrylate, glycidyl acrylate, 3,4 epoxycyclohexyl-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 preferred 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 suitable 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 A hydrazine derivative or a quaternary chlorinating agent that is a mixture of a tertiary amine and an acid. When preparing the aqueous epoxy resin dispersion, one or more of these can be used. 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;
Among 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, a part of the hydrazine derivative (C) having active hydrogen can be replaced with the active hydrogen-containing compound (D), but the replacement amount is 90 mol% or less, preferably 70 mol% or less, more preferably 10 to 10 mol%. It is suitable from the viewpoint of anticorrosion and adhesion to be in the range of 60 mol%.

  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 isocyanate and a hydroxyl group in the 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.
(a) m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate
(b) Compound (a) above or a mixture thereof and polyhydric alcohols (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,
(A) Aliphatic monoalcohols such as methanol, ethanol, propanol, butanol, octyl alcohol;
(B) Ethylene glycol and / or diethylene glycol monoethers, for example, monoethers such as methyl, ethyl, propyl (n-, iso), butyl (n-, iso, sec);
(C) aromatic alcohols such as phenol and cresol;
(D) 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. As the curing accelerating catalyst, for example, N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, bismuth nitrate and the like can be used.
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 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 as a neutralizing agent by reacting an epoxy group of an epoxy group-containing resin (that is, resin (A) or (B)) with a dibasic acid or secondary amine as an active hydrogen-containing compound. , Neutralization with water or acetic acid or phosphoric acid
(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 using both (1) and (2) above

  In the surface treatment composition, in addition to the specific water-dispersible resin described above, other water-dispersible resins and / or water-soluble resins include, for example, acrylic resins, urethane resins, polyester resins, epoxy resins, You may mix | blend 1 type (s) or 2 or more types, such as ethylene-type resin, alkyd-type resin, a phenol resin, and an olefin resin, by about 15 mass% by the ratio in the total resin solid content.

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 can be considered to improve the white rust resistance by including the silane coupling agent together with the 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, and N-β (aminoethyl) γ. -Aminopropyltrimexysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like. Specifically, KBM-903, KBE-903, and KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd. , KBE-602, KBE-603 (both 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 hexafluorometal acid, which is the component (c), acts on an inactive plating metal surface to activate the plating metal surface. The phosphoric acid and hexafluorometal acid may be used alone or in combination.
The type of hexafluorometal acid is not particularly limited, but in particular hexafluorometal containing one or more elements selected from Ti, Si, Zr such as fluorinated titanate, fluorinated zirconate, and fluoric acid. Acids are preferred, and one or more of these can be used.
The blending amount of phosphoric acid and / or hexafluorometal acid is 0.1 to 80 mass in total in terms of the solid content with respect to 100 mass parts of resin solid content of the aqueous epoxy resin dispersion as the component (a). Part, preferably 1 to 60 parts by weight, more preferably 5 to 50 parts by weight. If the blending amount of phosphoric acid and / or hexafluorometal acid 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, so that the corrosion resistance decreases.

A water-soluble phosphate can be added to the surface treatment composition as necessary for the purpose of improving the corrosion resistance. As the water-soluble phosphate, 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. The reason why the corrosion resistance is improved by adding the water-soluble phosphate is considered that the water-soluble phosphate forms a dense hardly soluble compound at the time of film formation.

  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 water-soluble phosphate is 0.1 to 60 parts by mass, preferably 0 with respect to 100 parts by mass of the resin solids of the aqueous epoxy resin dispersion as the component (a). It is appropriate that the content is 5 to 40 parts by mass, more preferably 1 to 30 parts by mass. If the blending amount of the water-soluble phosphate is less than 0.1 parts by mass, the effect of improving the corrosion resistance is not sufficient. On the other hand, if it exceeds 60 parts by mass, the soluble component of the film increases, so the corrosion resistance decreases, which is not preferable. .

A non-chromium rust preventive additive can be blended with the surface treatment composition as necessary for the purpose of improving the 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.
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 and / or calcium compound (e3) Slightly soluble phosphate compound (e4) Molybdate compound (e5) Vanadium compound (e6) Triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atom selected from (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 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, 300CF (all trade names) manufactured by Co., Ltd. can be used. In addition, as calcium ion exchange silica, WRGrace & Co. SHIELDEX C303, SHIELDEX AC3, SHIELDEX AC5 (all are trade names) manufactured by SHIELDEX, SHIELDEX SY710 (all are trade names) manufactured by Fuji Silysia Chemical Co., Ltd., and the like can be used. These silicas contribute to the formation of a dense and stable corrosion product of a plated metal in a corrosive environment, and the corrosion product is densely formed on the plating surface, thereby suppressing the promotion of corrosion.

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. This hardly soluble phosphorus compound is a metal plating zinc or aluminum eluted by corrosion, and forms a dense and hardly soluble protective film by a complexing reaction with phosphate ions dissociated by hydrolysis, thereby blocking the corrosion starting point. Inhibits corrosion reactions.

  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.

As the vanadium compound (e5), 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 (e6) 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.

  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 0 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). It is appropriate that the content is 5 to 30 parts by mass. 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. 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 component (e1) and one or more of the components (e3), (e4), (e5), (e6), and (e7) are used, particularly preferably (e3 Particularly excellent corrosion resistance can be obtained when all of the components (e) to (e7) are added in combination.

A conductive pigment can be blended with the surface treatment composition as necessary for the purpose of improving weldability.
As the conductive pigment, it is preferable to use one or more selected from metals, alloys, conductive carbon, iron phosphide, carbides, and semiconductor oxides as shown in the following (1) to (5).
(1) Metals such as zinc, nickel, iron, aluminum, cobalt, manganese, copper, tin or their alloy powder
(2) Conductive carbon powder such as conductive carbon and graphite powder
(3) Iron phosphide powder
(4) Carbide powders such as titanium carbide and silicon carbide
(5) Semiconductor oxide powders such as antimony-doped tin oxide, tin oxide-titanium oxide, tin oxide-barium sulfate, nickel oxide-aluminum, etc. The volume ratio is 5 to 70% by volume, preferably 10 to 40% by volume. When the blending amount (volume ratio) of the conductive pigment is less than 5% by volume, the effect of improving weldability cannot be obtained sufficiently. On the other hand, when the blending amount (volume ratio) exceeds 70% by volume, peeling of the film during press molding becomes remarkable, causing defects such as press cracks and wrinkles.

Further, 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 more kinds 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. If the dry film thickness is less than 0.01 μm, the corrosion resistance is insufficient.

Next, the upper layer film (organic inorganic film) formed as the second layer film on the surface treatment film will be described.
This upper layer film comprises a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000, a non-chromium rust preventive additive, a solid lubricant composed of an organic substance having a molecular weight of 5000 or less, a conductive pigment, It is a film formed by applying an organic inorganic composition for the upper layer containing lysine and drying it, and with respect to 100 parts by mass of the solid content of the high molecular weight epoxy group-containing resin (E), non-chromium-based rust preventive addition 0.1 to 120 parts by mass (solid content) of the agent, 0.1 to 30 parts by mass (solid content) of the solid lubricant, and the conductive pigment as a volume fraction in the total solid content of the upper film It is a film | membrane with a film thickness of 1-30 micrometers containing 5-70 volume%. This upper layer film also contains no chromium. By forming such a specific organic-inorganic film on the upper layer of the specific surface treatment film (lower film), particularly high corrosion resistance and weldability 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. Of these, bisphenol type epoxy resins are preferred. The generally used bisphenol type epoxy resin has 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.
As the bisphenol type epoxy resin, for example, a resin obtained by condensing epichlorohydrin and bisphenol to a high molecular weight in the presence of a catalyst such as an alkali catalyst, if necessary, epichlorohydrin and bisphenol, if necessary, an alkali catalyst Any of the resins obtained by polycondensation of this low molecular weight epoxy resin and bisphenol may be used by condensing in the presence of a catalyst such as a low molecular weight epoxy resin. 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, and bis (2-hydroxynaphthyl) methane. 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, a polyalkylene glycol-modified epoxy resin obtained by reacting polyalkylene glycol, polyisocyanate and an epoxy resin, or a modification obtained 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.
(a) 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;
(b) secondary monoamines such as diethylamine, diethanolamine, di-n- or -iso-propanolamine, N-methylethanolamine, N-ethylethanolamine;
(c) a secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and a dialkyl (meth) acrylamide by a Michael addition reaction;
(d) 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. A quaternary chlorinating agent reacts with an epoxy group in the presence of water as necessary to form a quaternary salt with an 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) comprising 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, film-forming properties, and the like.

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 resin composition for an upper layer 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 of 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.

Among the above amino resins, a part or all of the methylol group of the methylol melamine resin is a methyl ether melamine resin etherified with methyl alcohol, a butyl ether 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; cyclic aliphatic 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 or water, 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. Can mention blocking agents,
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 resin composition for upper film | membranes, it is 1-50 mass parts in the ratio of solid content with respect to 100 mass parts of solid content 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. As the curing accelerating catalyst, for example, N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, bismuth nitrate and the like can be used.
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 film of the present invention contains a non-chromium rust preventive additive for the purpose of improving the corrosion resistance. By incorporating such a non-chromium-based rust preventive additive into 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 calcium compounds (e3) Slightly soluble phosphate compounds (e4) Molybdate compounds (e5) Vanadium compounds (e6) Triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms selected from (e7) containing one or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Organic compounds The details and anticorrosion mechanism of the non-chromium rust preventive 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 120 parts by mass, preferably 0.5 to 30 in terms of the solid content with respect to 100 mass parts of the solid content of the high molecular weight epoxy group-containing resin (E). Mass parts. 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. This is not preferable because the corrosion resistance is deteriorated as well as the property.
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), (e4), (e5), (e6), and (e7) are used, particularly preferably (e3 Particularly excellent corrosion resistance is obtained when all of the components (e) to (e7) are added in combination.
Can be added.

In the upper layer film, a solid lubricant composed of an organic substance having a molecular weight of 5000 or less is blended for the purpose of improving the workability of the film. If the molecular weight of the solid lubricant exceeds 5000, the lubricity is inferior, and as a result, the post-processing corrosion resistance decreases.
Examples of the solid lubricant 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) Fluorine resin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin, etc.) , Polyvinyl fluoride resin, polyvinylidene fluoride resin, etc.

Among the above solid lubricants, polyethylene wax and fluororesin fine particles (in particular, polytetrafluoroethylene resin fine particles) are preferable. 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 0.1 to 30 parts by mass, preferably 1 to 10 parts by mass in terms of the solid content with respect to 100 mass parts of the solid content of the high molecular weight epoxy group-containing resin (E). Part. If the blending amount of the solid lubricant is less than 0.1 parts by mass, the lubricating effect is poor. On the other hand, if the blending amount exceeds 30 parts by mass, the paint adhesion deteriorates, which is not preferable.

  Solid lubricants include organic lubricants having a molecular weight of 5000 or less and fatty acid amide compounds (eg stearic acid amide, palmitic acid amide, methylene bisstearamide, ethylene bisstearamide, olein). Acid amides, esylic acid amides, alkylene bis fatty acid amides, etc.), metal soaps (eg, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metal sulfides (eg, molybdenum disulfide, tungsten disulfide, etc.) ), Graphite, fluorinated graphite, boron nitride, polyalkylene glycol, alkali metal sulfate or the like may be used in an appropriate amount.

In the upper layer film, a conductive pigment is blended for the purpose of improving the processability of the film.
The conductive pigment applicable to the present invention includes at least one selected from metals, alloys, conductive carbon, iron phosphide, carbides, and semiconductor oxides as shown in the following (1) to (5). It is preferable to use it.
(1) Metals such as zinc, nickel, iron, aluminum, cobalt, manganese, copper, tin or their alloy powder
(2) Conductive carbon powder such as conductive carbon and graphite powder
(3) Iron phosphide powder
(4) Carbide powders such as titanium carbide and silicon carbide
(5) Semiconductor oxide powders such as antimony-doped tin oxide, tin oxide-titanium oxide, tin oxide-barium sulfate, nickel oxide-aluminum, etc. The volume ratio is 5 to 70% by volume, preferably 10 to 40% by volume. When the blending amount (volume ratio) of the conductive pigment is less than 5% by volume, the weldability is insufficient and the continuous weldability is lowered. On the other hand, when the blending amount (volume ratio) exceeds 70% by volume, peeling of the film during press molding becomes remarkable, causing defects such as press cracks and wrinkles.

  The upper layer film of the surface-treated steel sheet of the present invention comprises a high molecular weight epoxy group-containing resin (E), a non-chromium rust preventive additive, a solid lubricant, and a conductive pigment as essential components, and if necessary, a curing agent. In addition, other oxide fine particles (eg, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, etc.), phosphomolybdate (eg, aluminum phosphomolybdate) are added as corrosion inhibitors. Organic phosphoric acid and its salts (for example, phytic acid, phytate, phosphonic acid, phosphonate, and their metal salts, alkali metal salts, alkaline earth metal salts, etc.), organic inhibitors (for example, hydrazine) And derivatives thereof, thiol compounds, thiocarbamates, and the like). Further, as necessary, organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments), coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.) , Inorganic pigments (for example, titanium oxide), chelating agents (for example, thiol), conductive pigments (for example, metal powders such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide), coupling 1 type (s) or 2 or more types, such as an agent (For example, a silane coupling agent, a titanium coupling agent, etc.) and a melamine cyanuric acid adduct, can be added.

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 aqueous, 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 1 to 30 μm. If the film thickness of the upper layer film is less than 1 μm, the corrosion resistance is insufficient. On the other hand, if the film thickness exceeds 30 μm, the weldability decreases.

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 the zinc-based plated steel sheet or the 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. 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 unpreferable.
An upper layer film is formed as a second layer film on the upper layer of the surface treatment film formed as described above. The organic inorganic composition for the upper layer film is applied to the surface-treated film surface so as to have the above-described film thickness, and is dried by heating. Application | coating of an organic inorganic composition should just be performed according to the method used for formation of the surface treatment film mentioned above.

  After application of the organic / inorganic composition, drying is usually performed without washing with water, but a washing process may be performed after application of the organic / inorganic 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 unpreferable.

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 (c) 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 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water (b) Silane Coupling agent: 1 to 300 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
On the upper layer, 0.1 to 120 parts by mass (solid content) of a non-chromium rust preventive additive with respect to 100 parts by mass of the high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 And 0.1-30 parts by mass (solid content) of a solid lubricant composed of an organic substance having a molecular weight of 5000 or less, and the volume ratio in the total solid content of the upper film is 5 to 70% by volume. An upper layer organic inorganic composition containing an amount of a conductive pigment is applied, and an upper layer film having a film thickness of 1 to 30 μm is formed by drying at an ultimate plate temperature of 30 to 150 ° C. A method for producing weldable high corrosion-resistant surface-treated steel sheets for automobiles.

[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. 0.1-50 mass parts (solid content) with respect to a part, The manufacturing method of the highly corrosion-resistant surface treatment steel plate for motor vehicles which can be welded characterized by the above-mentioned.
[3] In the production method of [1] or [2] above, the surface treatment composition for forming the surface treatment film further has a volume ratio of 5 to 70% by volume in the total solid content of the surface treatment film. A method for producing a weldable, highly corrosion-resistant surface-treated steel sheet for automobiles containing such an amount of conductive pigment.
[4] In the production method of [1] to [3], the conductive pigment is one or more selected from metals, alloys, conductive carbon, iron phosphide, carbides, and semiconductor oxides. A method for producing a weldable high corrosion-resistant surface-treated steel sheet for automobiles.
[5] The method according to any one of [1] to [4] above, wherein the non-chromium anticorrosive additive contains one or more selected from the following (e1) to (e7): The manufacturing method of the highly corrosion-resistant surface treatment steel plate for motor vehicles which can be welded.
(E1) Silicon oxide (e2) Calcium and / or calcium compound (e3) Slightly soluble phosphate compound (e4) Molybdate compound (e5) Vanadium compound (e6) Triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atom selected from (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds

[6] In the production method according to any one of [1] to [5] above, the organic inorganic composition for the upper layer further contains a curing agent having a group that crosslinks with a hydroxyl group. The manufacturing method of the highly corrosion-resistant surface-treated steel plate for motor vehicles which can be welded characterized by containing 1-50 mass parts (solid content) with respect to 100 mass parts per minute.
[7] In the production method of [6] above, the hardener having a group that crosslinks with a hydroxyl group is an amino resin (F) having an average of at least one imino group in one molecule. A method for producing a high corrosion resistance surface-treated steel sheet for automobiles.
[8] In the production method of [6], 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. Method for manufacturing a highly corrosion-resistant surface-treated steel sheet for automobiles.

[9] In the production method of [8] above, the polyisocyanate compound (G) is a weldable automobile characterized in that at least a part of the isocyanate group of the polyisocyanate compound is blocked with a blocking agent. A method for producing a highly corrosion-resistant surface-treated steel sheet.
[10] In the production method according to any one of [1] to [9], the high molecular weight epoxy group-containing resin (E) in the organic inorganic composition for upper layer is a hydrazine in which some or all of the compounds have active hydrogen. A method for producing a weldable, highly corrosion-resistant surface-treated steel sheet for automobiles, which is a modified epoxy group-containing resin modified with an active hydrogen-containing compound (H) comprising the derivative (I).
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, and as a combination of the film forms on the front and back surfaces of the plated steel sheet, for example, surface treatment film + upper layer film / no treatment, The surface treatment film + upper layer film / surface treatment film, surface treatment film + upper layer film / surface treatment film + upper layer film, and the like can be used.

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 hexafluorometal acid ( Table 4), a water-soluble phosphate (Table 5), and a non-chromium rust preventive additive (Table 6) are appropriately blended and stirred for a predetermined time using a paint disperser (sand grinder), and a surface treatment composition. Was prepared.
The 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, a stirrer, and a condenser tube, 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, 1121 g of Epicoat 834X90 (epoxy resin, manufactured by Shell Japan, epoxy equivalent 250), 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 became 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 the 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 organic inorganic composition for forming the upper layer film, the resin compositions shown in Table 7 and Table 8 are used, and non-chromium rust preventive additives (Table 6), conductive pigments (Table 9), and solid lubricants are used. An agent (Table 10) was appropriately blended and 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 (manufactured by 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. An epoxy resin solution having a solid content of 85% was obtained. 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, and then cooled. While adding 908 parts of methyl isobutyl ketone, pyrazole-modified epoxy resin solution F3 (resin composition (3)) having a solid content of 30% 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 (roll rolling force, rotational speed, etc.).
Next, the organic inorganic 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 organic inorganic composition or coating conditions (rolling force of roll, rotation speed, etc.).

Tables 11 to 28 show the results of evaluating the film composition and quality performance (corrosion resistance, post-processing corrosion resistance, powdering resistance, weldability, paint adhesion) 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 36 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 5% or more, less than 10% ○: White rust generation area ratio 10% or more, less than 30% ○-: White rust generation area ratio 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 according to 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 18 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 Industry Co., Ltd.
The evaluation criteria are as follows.
◎: White rust generation area ratio less than 5% ○ +: White rust generation area ratio 5% or more, less than 10% ○: White rust generation area ratio 10% or more, less than 30% ○-: White rust generation area ratio 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) Powdering resistance The sample was subjected to a draw bead test under the conditions of a bead tip diameter of 0.5 mmR, a bead height of 4 mm, a drawing speed of 200 mm / min, and a pressurizing force of 500 kgf, and the adhesive tape was adhered and peeled to the sliding part. The difference in weight of the sample before and after the test was measured, and this was converted per unit area and evaluated as follows.
◎: 5g / ^{m 2} following 〇: 5g / ^{m 2} greater than, 7g / ^{m 2} following 〇-: 7g / ^{m 2} greater than, 10g / ^{m 2} or less △: 10g / ^{m 2} greater than, 20g / ^{m 2} or less ×: 20g / M ² > (4) Weldability For each sample, a welding test with a continuous spotting property under the conditions of electrode used: CF type Cr—Cu electrode, applied pressure: 200 kgf, energization time: 10 cycles / 50 Hz, welding current: 10 kA And evaluated by the number of continuous hits. The evaluation criteria are as follows.
◎: 2000 points or more ○: 1000 points or more and less than 2000 points △: 500 points or more and less than 1000 points ×: Less than 500 points

(5) Paint adhesion The surface of each sample was coated with an intermediate coating “KPX-36” (film thickness 40 μm) manufactured by Kansai Paint Co., Ltd., and then “Lugabake B-531” manufactured by Kansai Paint Co., Ltd. The top coat (film thickness 40 μm) was applied. After immersing this sample in ion exchange water at 40 ° C. for 240 hours, the sample was taken out and allowed to stand at room temperature for 24 hours. 100 grids at intervals of 2 mm were cut into the coating film of this sample, the adhesive tape was adhered and peeled, and the peeled area ratio of the coating film was evaluated. The evaluation criteria are as follows.
◎: No peeling of coating film ◯: Less than 3% coating film peeling area ratio △: 3% or more coating film peeling area ratio less than 10% ×: 10% or more coating film peeling area ratio

In addition, * 1 to * 10 described in Tables 11 to 28 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 hexafluorometal acid)
* 5: No. in Table 5 (Water-soluble phosphate)
* 6: No. in Table 6 (Anti-rust additive)
* 7: parts by mass * 8: No. in Table 7 and Table 8 (Resin composition)
* 9: No. in Table 9 (Conductive pigment)
* 10: No. in Table 10 (Solid lubricant)
* 11: parts by mass * 12:% by volume of conductive pigment in the total solid content of the upper film

Claims (11)

The film thickness formed by applying and drying a surface treatment composition containing the following components (a) to (c) on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet 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 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water (b) Silane Coupling agent: 1 to 300 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
In the upper layer, a high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000, a non-chromium rust preventive additive, a solid lubricant composed of an organic substance having a molecular weight of 5000 or less, and a conductive pigment It is a film formed by applying and drying the organic inorganic composition for the upper layer, and it is a non-chromium rust preventive additive with respect to 100 parts by mass of the solid content of the high molecular weight epoxy group-containing resin (E) 0.1 to 120 parts by mass (solid content), 0.1 to 30 parts by mass (solid content) of a solid lubricant, and 5% by volume ratio in the total film solid content of the upper film. A high corrosion-resistant surface-treated steel sheet for automobiles that can be welded, characterized in that it has an upper film with a film thickness of 1 to 30 μm and containing 70% by volume.   The surface treatment composition for forming the surface treatment film further contains a non-chromium rust preventive additive in an amount of 0.1 to 50 parts by mass (100 parts by mass of resin solid content of the aqueous epoxy resin dispersion of component (a)). The weldable high corrosion-resistant surface-treated steel sheet for automobiles according to claim 1, comprising: a solid content).   The surface treatment composition for forming a surface treatment film further contains a conductive pigment, and the volume ratio in the total film solid content of the surface treatment film of the conductive pigment is 5 to 70% by volume. The high corrosion-resistant surface-treated steel sheet for automobiles according to claim 1 or 2, which is weldable.   The weldable according to any one of claims 1 to 3, wherein the conductive pigment is at least one selected from metals, alloys, conductive carbon, iron phosphide, carbides, and semiconductor oxides. A highly corrosion-resistant surface-treated steel sheet for automobiles. The weldable automobile height according to any one of claims 1 to 4, comprising at least one selected from the following (e1) to (e7) as a non-chromium rust preventive additive. Corrosion-resistant surface-treated steel sheet.
(E1) Silicon oxide (e2) Calcium and / or calcium compound (e3) Slightly soluble phosphate compound (e4) Molybdate compound (e5) Vanadium compound (e6) Triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atom selected from (e7) One or more N atoms selected from hydrazide compounds, pyrazole compounds, triazole compounds, tetrazole compounds, thiadiazole compounds, pyridazine compounds Contains organic compounds   The organic inorganic composition for the upper layer further contains 1 to 50 parts by mass (solid content) of a curing agent having a group that crosslinks with a hydroxyl group with respect to 100 parts by mass of the solid content of the high molecular weight epoxy group-containing resin (E). The high corrosion-resistant surface-treated steel sheet for automobiles according to any one of claims 1 to 5, wherein the steel sheet is weldable.   The high corrosion-resistant surface treatment for automobiles according to claim 6, 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. steel sheet.   The high corrosion resistant surface for automobiles according to claim 6, 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. Treated steel sheet.   The weldable highly corrosion-resistant surface-treated steel sheet for automobiles according to claim 8, wherein the polyisocyanate compound (G) is obtained by blocking at least a part of isocyanate groups of the polyisocyanate compound with a blocking agent.   Modified epoxy in which the high molecular weight epoxy group-containing resin (E) in the organic inorganic composition for the upper layer is 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 weldable high corrosion resistance surface-treated steel sheet for automobiles according to any one of claims 1 to 9, which is a base-containing resin. The coating thickness is obtained by applying a surface treatment composition containing the following components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and drying at a temperature of a final 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 20000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water (b) Silane Coupling agent: 1 to 300 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
(C) Phosphoric acid and / or hexafluorometal acid: 0.1 to 80 parts by mass (solid content) with respect to 100 parts by mass of resin solid content of the aqueous epoxy resin dispersion
On the upper layer, 0.1 to 120 parts by mass (solid content) of a non-chromium rust preventive additive with respect to 100 parts by mass of the high molecular weight epoxy group-containing resin (E) having a number average molecular weight of 6000 to 20000 And 0.1-30 parts by mass (solid content) of a solid lubricant composed of an organic substance having a molecular weight of 5000 or less, and the volume ratio in the total solid content of the upper film is 5 to 70% by volume. An upper layer organic inorganic composition containing an amount of a conductive pigment is applied, and an upper layer film having a film thickness of 1 to 30 μm is formed by drying at an ultimate plate temperature of 30 to 150 ° C. A method for producing weldable high corrosion-resistant surface-treated steel sheets for automobiles.