JP2010156020A - Surface-treated steel plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-treated steel plate which does not contain hexavalent chromium in a surface treatment composition or a film, and has excellent corrosion resistance and paint adhesiveness. <P>SOLUTION: The surface treatment composition (H) containing titanium-containing aqueous solution (A), fluorine-containing compound (B), an anion-based urethane resin and/or anion-based epoxy resin (C), organic phosphoric compound (D), vanadate compound (E), zirconium carbonate compound (F), and silane coupling agent (G) having glycidyl group which are obtained by mixing titanium compound such as hydrolysable titanium compound with hydrogen peroxide water at the predetermined ratio is applied on a surface of a zinc-based or aluminum-based plated steel plate, and dried. A surface-treated film has the film deposition of 0.2-3.0 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface-treated steel sheet that is most suitable for use in automobiles, home appliances, and building materials, and in particular, an environmentally-adapted surface-treated steel sheet that does not contain hexavalent chromium in the surface treatment composition and the surface treatment film formed thereby. It is about.

2. Description of the Related Art Conventionally, in the fields of automobiles, architecture, civil engineering, home appliances, etc., surface-treated steel sheets in which a chemical conversion film for suppressing white rust is formed on a plated steel sheet are widely used. Since this surface-treated steel sheet is often used after being coated, the chemical conversion film is required to have paint adhesion as well as corrosion resistance.
Many chemical conversion treatment techniques for imparting corrosion resistance to plated steel sheets have been proposed. Conventionally, chromate treatment with a treatment liquid containing chromic acid, dichromic acid or a salt thereof as a main component has been performed. However, chromate treatment uses hexavalent chromium, which is a pollution-controlling substance, and because of the environmental considerations and the waste liquid treatment of chromate treatment liquid requires a great deal of labor and expense, chromate-free technology that does not contain chromium. Is being considered. For example, Patent Documents 1 to 3 propose titanium-zirconium-based chromate-free treated metal plates.
JP 2004-2950 A International Publication No. 2003/93533 Pamphlet JP 2003-306777 A

However, these conventional chromate-free treatments cannot provide a surface-treated steel sheet having both excellent corrosion resistance and paint adhesion.
Accordingly, an object of the present invention is to solve such problems of the prior art, and to provide a surface-treated steel sheet which does not contain hexavalent chromium in the surface treatment composition or film and has excellent corrosion resistance and paint adhesion. is there.

The present inventors have studied a surface treatment composition that can solve the above-mentioned problems, and as a result, have obtained the following findings.
In order to impart corrosion resistance and paint adhesion to surface-treated steel sheets based on galvanized steel sheets and aluminum-based plated steel sheets, it is considered necessary to form a dense reaction layer on the plating film surface. When the reactivity is low, a dense reaction layer is not formed between the plating surface and the surface treatment film, and sufficient corrosion resistance and paint adhesion cannot be expressed. As a result, the inventors have found that it is important to add a fluorine-containing compound to the treatment liquid (surface treatment composition) to enhance the reactivity. As a result of further investigation, a specific titanium-containing aqueous liquid was combined with a fluorine-containing compound, an organic phosphate compound, a vanadic acid compound, and a zirconium carbonate compound, and a specific organic resin and a specific silane coupling were added. It is found that the addition of a complex agent provides excellent corrosion resistance comparable to that of chromate film while being chromate-free, as well as excellent paint adhesion, especially in a wet environment. did. This is because, by applying a surface treatment composition having the above component composition to form a film, a dense reaction layer is formed on the plating surface, and a high barrier property is imparted to the surface treatment film itself. It is presumed that this is because the adhesion at the top coating / surface treatment film interface and the surface treatment film / plating interface is significantly improved.

The present invention has been made on the basis of such knowledge and has the following gist.
[1] At least one selected from a hydrolyzable titanium compound, a hydrolyzable titanium compound low-condensate, titanium hydroxide, and a titanium hydroxide low-condensate on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet The titanium-containing aqueous liquid (A) obtained by mixing a seed titanium compound with hydrogen peroxide is 1 to 60% by mass in terms of the solid content, and the fluorine-containing compound (B) is 1 to 40% in terms of the solid content. %, An anionic urethane resin or / and an anionic epoxy resin (C) in a proportion of 30 to 90% by mass, an organic phosphoric acid compound (D) in a proportion of a solid content of 1 to 60% by mass, a vanadic acid compound Solid (E) is 0.1 to 30% by mass in terms of solid content, zirconium carbonate compound (F) is 0.1 to 20% by mass in terms of solid content, and silane coupling agent (G) having a glycidyl group is solid. In minutes The surface treatment composition (H) containing 1 to 50% by mass is coated and dried to have a surface treatment film having a film adhesion amount of 0.2 to 3.0 g / m ^2. Surface treated steel sheet.

[2] The surface-treated steel sheet according to [1], wherein the fluorine-containing compound (B) is at least one selected from zircon ammonium fluoride and zircon hydrofluoric acid.
[3] In the surface-treated steel sheet according to [1] or [2], the surface treatment composition (H) further contains 0.05 to 1% by mass of the nickel compound (I) in a solid content ratio. A surface-treated steel sheet.

  The surface-treated steel sheet of the present invention comprises a specific titanium-containing aqueous liquid, a fluorine-containing compound, a specific organic resin, an organic phosphoric acid compound, a vanadate compound, a zirconium carbonate compound, and a specific silane coupling agent. By having a treatment film with a surface treatment composition formulated with a predetermined ratio, a dense reaction layer is formed on the plating surface and a high barrier property is imparted to the surface treatment film itself, so it is chromate-free. However, excellent corrosion resistance comparable to the chromate film is obtained, and high paint adhesion is obtained. Moreover, when the surface treatment composition contains a nickel compound, excellent blackening resistance can be obtained.

The details of the present invention and the reasons for limitation will be described below.
Examples of the galvanized 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-plated steel sheet (for example, Zn-5% Al alloy-plated steel sheet, Zn-55% Al alloy-plated steel sheet), Zn-Mg alloy-plated steel sheet, Zn-Al-Mg alloy-plated steel sheet (for example, Zn-6% Al-3) % Mg alloy-plated steel sheet, Zn-11% Al-3% Mg alloy-plated steel sheet), and metal oxides and polymers in the plating film of these plated steel sheets Etc. can be used as dispersed zinc composite-plated steel sheet (for example, Zn-SiO ₂ dispersion plating steel plate).

Moreover, the multilayer plating steel plate which plated two or more layers of the same kind or different kind among the above plating 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 plated in advance with thinning such as Ni, and the above-described various plating may be performed thereon.
As a plating method, any feasible method such as an electrolytic method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method, a gas phase method, or the like may be adopted.
Furthermore, in order to prevent blackening of the plating, about 1 to 2000 ppm of one or more trace elements of Ni, Co, and Fe are deposited in the plating film, or one of Ni, Co, and Fe is deposited on the surface of the plating film. You may make it surface-treat with the alkaline aqueous solution or acidic aqueous solution containing the above, and precipitate these elements.

Next, the surface treatment film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet and the surface treatment composition for forming this film 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 includes a specific titanium-containing aqueous liquid (A), a fluorine-containing compound (B), and an anionic urethane. Resin or / and anionic epoxy resin (C), organophosphate compound (D), vanadic acid compound (E), zirconium carbonate compound (F), and silane coupling agent (G) having a glycidyl group It is formed by applying a surface treatment composition (H) containing a predetermined ratio and further containing a nickel compound (I) or the like, if necessary, and drying it. This surface treatment film does not contain hexavalent chromium (however, excluding chromium as an inevitable impurity).

  The reason why excellent corrosion resistance and paint adhesion can be obtained by forming such a surface-treated film is that, as described above, a dense reaction layer is formed on the plating surface, and the surface-treated film itself has a higher barrier. It is estimated that this is because the adhesiveness at the top coating / surface treatment film interface and the surface treatment film / plating interface is remarkably improved. In particular, for paint adhesion, a specific organic resin and a silane coupling agent are added in a specific ratio to a titanium-containing aqueous liquid combined with a specific metal salt, so that the top coating / surface treatment film interface is added. As a result, the adhesion strengthening effect by the functional group of the organic resin and the adhesion strengthening effect by the silanol group of the silane coupling agent at the surface treatment film / plating interface can be obtained in combination. It is considered a thing.

The titanium-containing aqueous liquid (A) contains at least one titanium compound selected from hydrolyzable titanium compounds, hydrolyzable titanium compound low condensates, titanium hydroxide and titanium hydroxide low condensates. It is an aqueous liquid containing titanium obtained by mixing with hydrogen oxide water.
The hydrolyzable titanium compound is a titanium compound having a hydrolyzable group directly bonded to titanium, and generates titanium hydroxide by reacting with water such as water or water vapor. The hydrolyzable titanium compound may be one in which all of the groups bonded to titanium are hydrolyzable groups, or a part of the groups bonded to titanium may be hydrolyzable groups.
The hydrolyzable group is not particularly limited as long as it generates titanium hydroxide by reacting with moisture as described above. For example, a lower alkoxyl group or a group that forms a salt with titanium (for example, Halogen atoms such as chlorine, hydrogen atoms, sulfate ions, etc.).

The hydrolyzable titanium compound containing a lower alkoxyl group as the hydrolyzable group is particularly represented by the general formula Ti (OR) ₄ (wherein R represents the same or different alkyl groups having 1 to 5 carbon atoms). Tetraalkoxy titanium is preferred. Examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, and a tert-butyl group. Can be mentioned.
Typical examples of the hydrolyzable titanium compound having a group capable of forming a salt with titanium as a hydrolyzable group include titanium chloride and titanium sulfate.

Moreover, the low condensate of a hydrolysable titanium compound is a low condensate of the above-mentioned hydrolysable titanium compounds. The low condensate may be one in which all of the groups bonded to titanium are hydrolyzable groups, or a part of the groups bonded to titanium may be hydrolyzable.
For hydrolyzable titanium compounds whose hydrolyzable group forms a salt with titanium (for example, titanium chloride, titanium sulfate, etc.), an aqueous solution of the hydrolyzable titanium compound and an alkaline solution such as ammonia or caustic soda are used. Orthotitanic acid (titanium hydroxide gel) obtained by the reaction can also be used as a low condensate.

As the low condensate of the hydrolyzable titanium compound and the low condensate of titanium hydroxide, a compound having a condensation degree of 2 to 30 can be used, and a compound having a condensation degree of 2 to 10 is particularly preferable. When the condensation degree exceeds 30, a white precipitate is formed when mixed with hydrogen peroxide, and a stable titanium-containing aqueous liquid cannot be obtained. That is, if the degree of condensation is 30 or less, a stable titanium-containing aqueous liquid can be obtained by mixing with hydrogen peroxide.
The hydrolyzable titanium compounds, low condensates of hydrolysable titanium compounds, titanium hydroxide, and low condensates of titanium hydroxide can be used alone or in combination of two or more thereof. Tetraalkoxy titanium, which is a hydrolyzable titanium compound represented by the formula, is particularly preferred. The reason for this is that tetraalkoxytitanium does not affect the film performance such as corrosion resistance because the alcohol produced when hydrolyzed volatilizes in the process of drying the surface treatment composition, and has particularly excellent film performance. It is because it is obtained.

As the titanium-containing aqueous liquid (A), any conventionally known liquid can be used without particular limitation as long as it is an aqueous liquid containing titanium obtained by mixing the above-described titanium compound and hydrogen peroxide solution. Specifically, the following can be mentioned.
(I) A titanyl ion hydrogen peroxide complex or an aqueous solution of titanic acid (peroxotitanium hydrate) obtained by adding hydrogen peroxide to a hydrous titanium oxide gel or sol (JP-A 63-35419, JP-A 1-2224220 gazette).

(Ii) A liquid for forming a titania film obtained by synthesizing a titanium hydroxide gel produced from an aqueous solution of titanium chloride or titanium sulfate and a basic solution with a hydrogen peroxide solution (Japanese Patent Laid-Open No. 9-71418, (See Kaihei 10-67516).
When obtaining this titania film-forming liquid, titanium hydroxide gel called orthotitanic acid is precipitated by reacting an aqueous solution of titanium chloride or titanium sulfate having a salt-forming group with titanium and an alkaline solution such as ammonia or caustic soda. Let Next, the titanium hydroxide gel is separated by decantation with water, washed thoroughly with water, further added with hydrogen peroxide water, and excess hydrogen peroxide is decomposed and removed, whereby a yellow transparent viscous liquid can be obtained.

The precipitated orthotitanic acid is in a gel state polymerized by polymerization of OH or hydrogen bonds, and cannot be used as an aqueous liquid containing titanium as it is. When hydrogen peroxide solution is added to this gel, a part of OH is in a peroxidized state, dissolved as a peroxotitanate ion or in a kind of sol state in which the polymer chain is divided into low molecules, and excess hydrogen peroxide Is decomposed into water and oxygen, and can be used as an aqueous liquid containing titanium for forming an inorganic film.
Since this sol contains only oxygen and hydrogen atoms in addition to titanium atoms, when it is changed to titanium oxide by drying or firing, only water and oxygen are generated, so carbon components necessary for thermal decomposition such as sol-gel method and sulfate Further, it is not necessary to remove the halogen component, and a titanium oxide film having a relatively high density can be formed even at a low temperature.

(Iii) Hydrogen peroxide is added to an aqueous solution of an inorganic titanium compound such as titanium chloride or titanium sulfate to form peroxotitanium hydrate, and then the solution obtained by adding a basic substance is allowed to stand or be heated. A titanium oxide forming solution obtained by forming a precipitate of a titanium hydrate polymer, and then removing hydrogen and other dissolved components derived from at least a titanium-containing raw material solution (Japanese Patent Application Laid-Open 2000-247638, JP-A-2000-247639).

The titanium-containing aqueous liquid (A) using a hydrolyzable titanium compound and / or a low condensate thereof as a titanium compound (hereinafter referred to as “hydrolyzable titanium compound a” for convenience of explanation) contains hydrolyzable titanium compound a. It can be obtained by reacting with hydrogen oxide water at a reaction temperature of 1 to 70 ° C. for about 10 minutes to 20 hours.
In the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a, the hydrolyzable titanium compound a is hydrolyzed with water by reacting the hydrolyzable titanium compound a with hydrogen peroxide. A product obtained by producing a hydroxyl group-containing titanium compound and then coordinating hydrogen peroxide to this hydroxyl group-containing titanium compound, and this hydrolysis reaction and coordination by hydrogen peroxide occur simultaneously. It produces a chelate solution that is extremely stable at room temperature and can withstand long-term storage. The titanium hydroxide gel used in the conventional manufacturing method is partially three-dimensionalized by Ti—O—Ti bonds, and the titanium-containing aqueous liquid (A) obtained by reacting this gel with hydrogen peroxide is composition and stable. Sex is essentially different.

  Further, when the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a is heated or autoclaved at 80 ° C. or higher, a titanium oxide dispersion containing ultrafine particles of crystallized titanium oxide is obtained. When the heat treatment or autoclave treatment is less than 80 ° C., crystallization of titanium oxide does not proceed sufficiently. That is, if the heat treatment or autoclave treatment is performed at 80 ° C. or higher, crystallization of titanium oxide can be sufficiently advanced. The titanium oxide dispersion produced in this manner desirably has an average particle diameter of ultrafine titanium oxide particles of 10 nm or less, preferably about 1 to 6 nm. When the average particle diameter of the titanium oxide ultrafine particles is larger than 10 nm, the film forming property is deteriorated (when the film is dried after coating to form a film, cracking occurs at a film thickness of 1 μm or more), which is not preferable. That is, when the average particle diameter of the titanium oxide ultrafine particles is 10 nm or less, the film-forming property is excellent (when the film is dried after coating to form a film, cracking does not occur when the film thickness is 1 μm or more). Moreover, if the average particle diameter of the titanium oxide ultrafine particles is 1 nm or more, it is preferable because the surface treatment composition can be maintained in a state where the viscosity does not increase. The appearance of this titanium oxide dispersion is translucent. Such a titanium oxide dispersion can also be used as the titanium-containing aqueous liquid (A).

The surface treatment composition (H) containing the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a is applied to the surface of the plated steel plate and dried (for example, heat-dried at a low temperature), thereby adhering to itself. A dense titanium oxide-containing film (surface treatment film) having excellent properties can be formed.
The heating temperature of the steel sheet after the application of the surface treatment composition (H) is, for example, preferably 200 ° C. or lower, particularly preferably 150 ° C. or lower. Amorphous) titanium oxide-containing film can be formed.
In addition, when the titanium oxide dispersion obtained through the heat treatment or autoclave treatment as described above at 80 ° C. or more is used as the titanium-containing aqueous liquid (A), the crystal can be obtained by simply applying the surface treatment composition (H). It is useful as a coating material for materials that cannot be heat-treated.

In addition, as the titanium-containing aqueous liquid (A), a titanium-containing aqueous liquid (A1) obtained by reacting the hydrolyzable titanium compound a with hydrogen peroxide in the presence of a titanium oxide sol can also be used. .
The titanium oxide sol is a sol in which amorphous titania fine particles and / or anatase type titania fine particles are dispersed in water (for example, an aqueous organic solvent such as alcohol or alcohol ether may be added if necessary). As this titanium oxide sol, conventionally known ones can be used. For example, (i) a titanium oxide aggregate obtained by hydrolyzing a titanium-containing solution such as titanium sulfate or titanyl sulfate, (ii) titanium alkoxide, etc. Titanium oxide aggregates obtained by hydrolyzing organic titanium compounds of the above, (iii) Titanium oxide aggregates obtained by hydrolyzing or neutralizing titanium halide solutions such as titanium tetrachloride, etc. An amorphous titania sol dispersed in water, or a sol obtained by calcining the titanium oxide aggregate to form anatase-type titanium fine particles and dispersing this in water can be used.

  In the firing of the amorphous titania, the amorphous titania can be converted into anatase titania by firing at a temperature of at least the crystallization temperature of anatase, for example, a temperature of 400 ° C. to 500 ° C. or more. Examples of the aqueous sol of titanium oxide include, for example, TKS-201 (trade name, manufactured by Teika, anatase crystal form, average particle diameter 6 nm), TA-15 (trade name, manufactured by Nissan Chemical Co., anatase crystal form). , STS-11 (trade name, manufactured by Ishihara Sangyo Co., Ltd., anatase crystal form) and the like.

  In the titanium-containing aqueous liquid (A1), the mass ratio x / y between the titanium oxide sol x and the titanium hydrogen peroxide reactant y (reaction product of the hydrolyzable titanium compound a and hydrogen peroxide solution) is 1 / A range of 99 to 99/1, preferably about 10/90 to 90/10 is suitable. If the mass ratio x / y is less than 1/99, the effect of adding the titanium oxide sol cannot be sufficiently obtained in terms of stability, photoreactivity, etc. On the other hand, if it exceeds 99/1, the film forming property is inferior. Absent. That is, if the mass ratio x / y is 1/99 or more, the effect of adding the titanium oxide sol can be sufficiently obtained in terms of stability, photoreactivity, and the like, and if it is 99/1 or less, it is excellent. Since film forming property is obtained, it is preferable.

The titanium-containing aqueous liquid (A1) can be obtained by reacting the hydrolyzable titanium compound a with hydrogen peroxide at a reaction temperature of 1 to 70 ° C. for about 10 minutes to 20 hours in the presence of a titanium oxide sol.
The production form and characteristics of the titanium-containing aqueous liquid (A1) are the same as those of the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a described above, but in particular, by using a titanium oxide sol. , It is possible to suppress a partial condensation reaction during the synthesis to increase the viscosity. The reason is considered to be that the condensation reaction product is adsorbed on the surface of the titanium oxide sol, and polymerization in a solution state is suppressed.

  In addition, when the titanium-containing aqueous liquid (A1) is heated or autoclaved at 80 ° C. or higher, a titanium oxide dispersion containing ultrafine particles of crystallized titanium oxide is obtained. The titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a described above also describes the temperature conditions for obtaining this titanium oxide dispersion, the particle diameter of the crystallized titanium oxide ultrafine particles, the appearance of the dispersion, etc. It is the same. Such a titanium oxide dispersion can also be used as the titanium-containing aqueous liquid (A1).

Similar to the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a described above, the surface treatment composition (H) containing the titanium-containing aqueous liquid (A1) is applied to the surface of the plated steel sheet and dried (for example, By heating and drying at a low temperature, it is possible to form a dense titanium oxide-containing film (surface-treated film) having excellent adhesion by itself.
The heating temperature of the steel sheet after applying the surface treatment composition (H) is, for example, preferably 200 ° C. or less, particularly preferably 150 ° C. or less. By heating and drying at such a temperature, anatase type oxidation slightly containing hydroxyl groups A titanium-containing film can be formed.
As described above, of the titanium-containing aqueous liquid (A), the titanium-containing aqueous liquid (A) and the titanium-containing aqueous liquid (A1) using the hydrolyzable titanium compound a are excellent in storage stability, corrosion resistance, and the like. It is particularly preferable to use these in the present invention.

  The compounding ratio of hydrogen peroxide water to at least one titanium compound selected from hydrolyzable titanium compounds, hydrolyzable titanium compound low condensates, titanium hydroxide, titanium hydroxide low condensates is titanium compounds It is preferably 0.1 to 100 parts by mass, preferably 1 to 20 parts by mass in terms of hydrogen peroxide with respect to 10 parts by mass. If the mixing ratio of the hydrogen peroxide solution is less than 0.1 parts by mass in terms of hydrogen peroxide, chelate formation is not sufficient and white turbid precipitation occurs. On the other hand, when the amount exceeds 100 parts by mass, unreacted hydrogen peroxide tends to remain, and dangerous active oxygen is released during storage, which is not preferable. That is, if the blending ratio of hydrogen peroxide water is 0.1 parts by mass or more in terms of hydrogen peroxide, chelate formation is sufficient, so that no cloudy precipitation occurs. It is preferable because unreacted hydrogen peroxide does not remain and active oxygen is not released during storage.

The hydrogen peroxide concentration of the hydrogen peroxide solution is not particularly limited, but it is preferably about 3 to 30% by mass from the viewpoint of ease of handling and the solid content of the product liquid related to coating workability.
Other sols and pigments can be added and dispersed in the titanium-containing aqueous liquid (A) as necessary. Examples of the additive include commercially available titanium oxide sol, titanium oxide powder, mica, talc, silica, barita, clay, and the like, and one or more of these can be added.

The addition amount of the titanium-containing aqueous liquid (A) in the surface treatment composition (H) is 1 to 60% by mass, preferably 2 to 40% by mass in terms of the solid content from the viewpoint of the stability of the treatment liquid. . The treatment liquid stability is inferior in any case where the addition amount (solid content ratio) of the titanium-containing aqueous liquid (A) is less than 1 mass% or more than 60 mass%.
In the present invention, the ratio of the solid content of each component in the surface treatment composition refers to each component in the non-volatile content / heating (heat drying after application of the surface treatment composition) residue of the surface treatment composition. The ratio of the non-volatile content and heating (heat drying after applying the surface treatment composition) residue.

The fluorine-containing compound (B) is blended in order to enhance the reactivity between the treatment liquid (surface treatment composition) and the plating surface and form a dense reaction layer from the viewpoint of improving the corrosion resistance. Examples of the fluorine-containing compound (B) include zircon ammonium fluoride, zircon potassium fluoride, zircon hydrofluoric acid, titanium ammonium fluoride, hydrofluoric acid, and ammonium hydrofluoride. Species or two or more can be used. Among these, from the viewpoint of imparting corrosion resistance, it is preferable to use at least one selected from zircon ammonium fluoride and zircon hydrofluoric acid.
The addition amount of the fluorine-containing compound (B) in the surface treatment composition (H) is 1 to 40% by mass, preferably 2 to 30% by mass in terms of solid content. When the addition amount of the fluorine-containing compound (B) is less than 1% by mass, the reactivity between the treatment liquid and the plating surface is inferior, so that sufficient corrosion resistance cannot be obtained. On the other hand, if it exceeds 40% by mass, the etching property of the treatment liquid becomes high. As a result, the plating surface is excessively etched, and the corrosion resistance is deteriorated.

  The anionic urethane resin and / or anionic epoxy resin (C) includes a resin having a group that can be anionized in an aqueous medium such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group in the molecule. A conventionally well-known thing can be used widely. Among these, those having a carboxyl group as an anionic group are preferred from the viewpoint of corrosion resistance and the like. If necessary, the anionic group may be a part or all of these functional groups as amine compounds such as ethanolamine and triethylamine; ammonia water; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide. Can be used after neutralization.

As an anionic urethane resin, a polyurethane comprising a polyol and a diisocyanate such as polyester polyol, polyether polyol or acrylic polyol is a low molecular weight compound having two or more active hydrogens such as diol and diamine as required. Those that are chain-extended in the presence of an extender and stably dispersed or dissolved in water can be suitably used.
As a method for stably dispersing or dissolving the polyurethane resin in water, for example, the following method can be used.

(1) A method of imparting hydrophilicity by introducing an anionic group such as a carboxyl group into the side chain or terminal of a polyurethane polymer, and dispersing or dissolving in water by self-emulsification. Specifically, for example, it can be synthesized by reacting a polyisocyanate, a polyol, and an active hydrogen group-containing compound having an anionic group.
(2) Compulsory polyurethane polymer with the reaction completed or polyurethane polymer with terminal isocyanate group blocked with a blocking agent such as oxime, alcohol, phenol, mercaptan, amine, sodium bisulfite using anionic emulsifier and mechanical shear force To disperse in water. Further, a method in which a urethane polymer having a terminal isocyanate group is mixed with water, an emulsifier, and a chain extender, and dispersion and high molecular weight are simultaneously performed using mechanical shearing force.

  Examples of the polyisocyanate that can be used for the synthesis of the polyurethane-based resin include aromatic, alicyclic or aliphatic diisocyanates. Specifically, hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3′-dimethoxy- 4,4'-biphenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 1,3- (diisocyanatomethyl) cyclohexanone, 1,4- (diisocyanatomethyl) cyclohexanone, 4,4'-di Isocyanatocyclohexanone, 4,4'-methylenebis (cyclohexyl isocyanate), isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, diphenyl Down diisocyanate, m- phenylene diisocyanate, 2,4-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-biphenylene, etc. diisocyanate and the like. Among these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate are particularly preferable.

The active hydrogen group-containing compound having an anionic group has an anionic group such as a carboxyl group or a sulfonyl group, and can react with an isocyanate group, for example, an active hydrogen group such as a hydroxyl group or an amino group. 2 active hydrogens in one molecule such as 2,2-dimethylolacetic acid, 2,2-dimethylollactic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, etc. A compound having a group can be preferably used.
As the polyol, the polyester polyol, polyether polyol, acrylic polyol, and the like can be used. By replacing a part of the polyol with, for example, an amino group-containing epoxy resin, an epoxy-modified anionic polyurethane resin is obtained. You can also.
Examples of commercially available anionic polyurethane resins include Hydran (registered trademark) AP-10, AP-20, AP-30, HW-330, HW-340, HW-350, and WLS-201. , WLS-210, WLS-221 (both trade names, manufactured by Dainippon Ink & Chemicals, Inc.), Superflex (registered trademark) 110, 130, 150, 150HS, 170 (both products) Name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

The anionic epoxy resin is obtained by introducing, for example, an anionic group such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group into the molecule, and among them, a carboxyl group is preferable from the viewpoint of corrosion resistance.
The carboxyl group-containing epoxy resin can be easily added by, for example, adding a polybasic acid anhydride to a part of the hydroxyl group of the epoxy resin by a half esterification reaction at a temperature of about 100 to about 180 ° C. Obtainable.
As the epoxy resin, an epoxy resin having at least one epoxy group in one molecule obtained by a reaction between a polyphenol compound and epichlorohydrin can be used.

  As the polyphenol compound that can be used for the production of the epoxy resin, those known per se can be used, and examples of such a polyphenol compound include bis (4-hydroxyphenyl) -2,2-propane (bisphenol A). ), 4,4-dihydroxybenzophenone, bis (4-hydroxyphenyl) methane (bisphenol F), bis (4-hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1,1-isobutane, Bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane, tetra (4-hydroxyphenyl) -1,1,2,2-ethane, 4,4- Dihydroxydiphenyl sulfone (bisphenol S), phenol novolac, cresol no Or the like can be mentioned rack.

Among epoxy resins obtained by the reaction of a polyphenol compound and epichlorohydrin, bisphenol type epoxy resins, particularly bisphenol A type epoxy resins are preferred from the viewpoint of long-term corrosion resistance.
Examples of such commercially available epoxy resins include those sold by Japan Epoxy Resins Co., Ltd. under trade names such as jER828EL, jER1002, jER1004, and jER1007.
As the epoxy resin, a modified epoxy resin modified with a fatty acid or the like may be used for the purpose of improving coating film performance and compatibility with other resins.
Examples of the acid anhydride include dibasic acid anhydrides such as succinic acid, maleic acid, phthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, and trimellitic anhydride. The tribasic acid monoanhydride can also be used.

As another method for introducing an anionic group into an epoxy resin, the epoxy resin is modified with acrylic or urethane having an anionic group. In this case, the anionic group may be introduced after the modification.
For example, in the case of an acrylic modified epoxy resin, an unsaturated group is introduced into the epoxy resin by reacting the epoxy group of the epoxy resin with a compound having a carboxyl group and an unsaturated group such as acrylic acid or methacrylic acid. It can be obtained by polymerizing an unsaturated monomer in the presence of a saturated group-containing epoxy resin. By using an anionic group-containing monomer as a part of the unsaturated monomer, an anionic group can be easily introduced into the acrylic modified epoxy resin.

Examples of commercially available anionic epoxy resins include Watersol (registered trademark) S-370, CD-540P, CD-550LAP, EFD-5501P, EFD-5509, BM-1000, and S-. 319-HV (all trade names, manufactured by Dainippon Ink & Chemicals, Inc.), MODEPICS (registered trademark) 301, 302, 303, 304 (all trade names, manufactured by Arakawa Chemical Industries, Ltd.), etc. Can be mentioned.
The addition amount of the anionic urethane resin and / or the anionic epoxy resin (C) in the surface treatment composition (H) is 30 to 90% by mass, preferably 40 to 80% by mass in terms of solid content. When the addition amount of the anionic urethane resin and / or the anionic epoxy resin (C) is less than 30% by mass, sufficient paint adhesion cannot be obtained. On the other hand, when it exceeds 90% by mass, the barrier property due to the inorganic component is lowered, so that it is necessary to increase the coating amount in order to ensure the corrosion resistance, and the conductivity is lowered.

  Examples of the organic phosphate compound (D) include 1-hydroxymethane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxypropane-1,1-diphosphonic acid, and the like. Suitable examples include hydroxyl group-containing organic phosphorous acid; carboxyl group-containing organic phosphorous acid such as 2-hydroxyphosphonoacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, and salts thereof. These 1 type (s) or 2 or more types can be used.

The organic phosphoric acid compound (D) has an effect of improving the storage stability of the titanium-containing aqueous liquid (A). Among them, 1-hydroxyethane-1,1-diphosphonic acid has a particularly large effect. It is particularly preferred to use this.
The addition amount of the organic phosphoric acid compound (D) in the surface treatment composition (H) is 1 to 60 in terms of the solid content from the viewpoint of storage stability of the titanium-containing aqueous liquid (A) and water-resistant adhesion. % By mass, preferably 2 to 50% by mass. When the addition amount of the organic phosphate compound (D) is less than 1% by mass, the effect of improving the storage stability of the titanium-containing aqueous liquid (A) is small. On the other hand, when it exceeds 60 mass%, phosphoric acid exists excessively, resulting in deterioration of water resistance.

Examples of the vanadate compound (E) include lithium metavanadate, potassium metavanadate, sodium metavanadate, ammonium metavanadate, and anhydrous vanadate, and one or more of these can be used. Of these, ammonium metavanadate is preferable from the viewpoint of water adhesion resistance.
The addition amount of the vanadic acid compound (E) in the surface treatment composition (H) is 0.1 to 30% by mass, preferably 0.5 to 20% by mass in terms of solid content from the viewpoint of corrosion resistance. When the addition amount of the vanadic acid compound (E) is less than 0.1% by mass, the effect of improving the corrosion resistance is insufficient. On the other hand, when it exceeds 30 mass%, since V exists excessively, sufficient corrosion resistance cannot be expressed.

Examples of the zirconium carbonate compound (F) include salts of zirconium carbonate such as sodium, potassium, lithium, and ammonium, and one or more of these can be used. Of these, ammonium zirconium carbonate is preferable from the viewpoint of water-resistant adhesion.
The addition amount of the zirconium carbonate compound (F) in the surface treatment composition (H) is 0.1 to 20% by mass, preferably 0.2 to 15% by mass in terms of solid content from the viewpoint of corrosion resistance and the like. . When the added amount of the zirconium carbonate compound (F) is less than 0.1% by mass, the effect of improving the corrosion resistance is insufficient. On the other hand, when it exceeds 20% by mass, Zr is excessively present, so that sufficient corrosion resistance cannot be exhibited.

Examples of the silane coupling agent (G) having a glycidyl group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxy. Examples thereof include propylmethyldiethoxysilane, and one or more of these can be used.
The addition amount of the silane coupling agent (G) in the surface treatment composition (H) is 1 to 50% by mass, preferably 4 to 40% by mass in terms of the solid content. When the addition amount of the silane coupling agent (C) is less than 1% by mass, sufficient paint adhesion cannot be obtained. On the other hand, when it exceeds 50 mass%, storage stability cannot be ensured.

In order to improve blackening resistance, the surface treatment composition (H) preferably further contains 0.05 to 1% by mass of the nickel compound (I) in a solid content ratio. By containing the nickel compound (I) in such a range, excellent blackening resistance and corrosion resistance can be obtained. The more preferable content of the nickel compound (I) is 0.1 to 1% by mass.
Examples of the nickel compound (I) include nickel acetate, nickel nitrate, nickel sulfate and the like, and one or more of these can be used. Of these, nickel acetate is preferred from the viewpoint of improving blackening resistance.

For the surface treatment composition (H), if necessary, for example, etching agents such as resin fine particles and inorganic phosphate compounds, heavy metal compounds other than the components defined by the present invention, thickeners, surfactants, lubricants A property-imparting agent (polyethylene wax, fluorine-based wax, carnauba wax, etc.), a rust preventive agent, a color pigment, an extender pigment, a rust preventive pigment, and a dye can be blended.
Further, the surface treatment composition (H) can be used as diluted with a hydrophilic solvent such as methanol, ethanol, isopropyl alcohol, an ethylene glycol solvent, or a propylene glycol solvent, if necessary.
The adhesion amount of the surface treatment film formed by the surface treatment composition (H) is 0.2 to 3.0 g / m ² , preferably 0.3 to 2.0 g / m ² . When the coating amount is less than 0.2 g / m ² , the corrosion resistance is inferior. On the other hand, when it exceeds 3.0 g / m ² , the coating adheres to the roll or mold during roll forming or pressing, and the appearance after pressing is inferior. .

In order to produce the surface-treated steel sheet of the present invention, a titanium-containing aqueous liquid (A), a fluorine-containing compound (B), an anionic urethane resin as described above is formed on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet. Or / and contains an anionic epoxy resin (C), an organic phosphate compound (D), a vanadate compound (E), a zirconium carbonate compound (F) and a silane coupling agent (G) having a glycidyl group, preferably Furthermore, after apply | coating the surface treatment composition (H) (treatment liquid) containing nickel compound (I), it dries without washing with water normally.
Further, the titanium-containing aqueous liquid (A) and the surface treatment composition (H) may further contain other additive components as mentioned above, if necessary.

The method for applying the surface treatment composition (treatment liquid) may be any method that allows the treatment liquid to adhere to the surface of the plated steel sheet, such as spray + roll squeezing, roll coater, or dipping. Also, the drying method after application is arbitrary, for example, a hot air method, an induction heating method, an electric furnace method, or the like.
The drying temperature (steel plate temperature) of the applied surface treatment composition (treatment liquid) is preferably about 40 to 200 ° C. When the drying temperature is less than 40 ° C., the film formation is insufficient and the film has poor corrosion resistance. On the other hand, even if it is dried at a plate temperature exceeding 200 ° C., the effect of improving the performance such as corrosion resistance corresponding to the drying temperature cannot be obtained. That is, if the drying temperature is 40 ° C. or higher, the film formation is sufficient and the corrosion resistance is excellent. On the other hand, if it is 200 ° C. or lower, the performance such as the corrosion resistance corresponding to the drying temperature is sufficiently improved. can get.

The titanium-containing aqueous liquid (A) and components (B) to (G) and (I) used in the surface treatment composition are shown below.
[Production of titanium-containing aqueous liquid (A)]
Production Example 1 (Titanium-containing aqueous liquid T1)
Ammonia water (1: 9 = ammonia: water mass ratio) was added dropwise to a solution in which 5 cc of a titanium tetrachloride 60 mass% solution was made 500 cc with distilled water to precipitate a low condensation product of titanium hydroxide. After washing with distilled water, 10 cc of a 30% by mass hydrogen peroxide solution was added and stirred to obtain a yellow translucent viscous titanium-containing aqueous liquid T1 containing titanium.
Production Example 2 (Titanium-containing aqueous liquid T2)
A mixture of 10 parts by mass of tetraiso-propoxytitanium and 10 parts by mass of iso-propanol was dropped into a mixture of 30 parts by mass of 10 parts by mass of hydrogen peroxide and 100 parts by mass of deionized water with stirring at 20 ° C. over 1 hour. did. Thereafter, aging was carried out at 25 ° C. for 2 hours to obtain a yellow transparent, slightly viscous titanium-containing aqueous liquid T2.
Production Example 3 (Titanium-containing aqueous liquid T3)
A titanium-containing aqueous liquid T3 was obtained under the same production conditions as in Production Example 2 except that tetra-n-butoxy titanium was used instead of tetraiso-propoxy titanium used in Production Example 2.

Production Example 4 (Titanium-containing aqueous liquid T4)
In the same production conditions as in Production Example 2, except that a tetramer of tetraiso-propoxytitanium (low condensation product of tetraiso-propoxytitanium) was used instead of tetraiso-propoxytitanium used in Production Example 2, titanium was used. A contained aqueous liquid T4 was obtained.
Production Example 5 (Titanium-containing aqueous liquid T5)
A titanium-containing aqueous liquid was produced under the same production conditions as in Production Example 2, except that hydrogen peroxide was used in 3 times the amount of Production Example 2, dropped at 50 ° C over 1 hour, and further aged at 60 ° C for 3 hours. T5 was obtained.
Production Example 6 (Titanium-containing aqueous liquid T6)
The titanium-containing aqueous liquid T3 produced in Production Example 3 was further heat-treated at 95 ° C. for 6 hours to obtain a white yellow translucent titanium-containing aqueous liquid T6.
Production Example 7 (Titanium-containing aqueous liquid T7)
A mixture of 10 parts by mass of tetraiso-propoxytitanium and 10 parts by mass of iso-propanol, 5 parts by mass (solid content) of “TKS-203” (trade name, manufactured by Teika Co., Ltd.), 30% by mass hydrogen peroxide solution The mixture was added dropwise to a mixture of 10 parts by mass and 100 parts by mass of deionized water with stirring at 10 ° C. over 1 hour. Thereafter, the mixture was aged at 10 ° C. for 24 hours to obtain a yellow transparent, slightly viscous titanium-containing aqueous liquid T7.

[Fluorine-containing compound (B)]
B1: Zircon ammonium fluoride B2: Zircon hydrofluoric acid B3: Zircon sodium fluoride B4: Zircon potassium fluoride [anionic urethane resin / anionic epoxy resin (C)]
C1: Superflex 110 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., water-based polyurethane resin)
C2: Superflex 150 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., water-based polyurethane resin)
C3: Hydran AP-20 (trade name, manufactured by Dainippon Ink & Chemicals, Inc., aqueous polyurethane resin)
C4: Hydran HW-340 (trade name, manufactured by Dainippon Ink and Chemicals, water-based polyurethane resin)
C5: Watersol S-370 (trade name, manufactured by Dainippon Ink and Chemicals, anionic epoxy resin)
C6: Watersol CD-550LAP (trade name, manufactured by Dainippon Ink and Chemicals, anionic epoxy resin)
C7: MODEPICS 302 (trade name, manufactured by Arakawa Chemical Industries, Ltd., anionic epoxy resin)
C8: MODEPICS 303 (trade name, manufactured by Arakawa Chemical Industries, Ltd., anionic epoxy resin)

[Organic Phosphate Compound (D)]
D1: 1-hydroxymethane-1,1-diphosphonic acid D2: 1-hydroxyethane-1,1-diphosphonic acid [vanadic acid compound (E)]
E1: ammonium metavanadate E2: sodium metavanadate [zirconium carbonate compound (F)]
F1: ammonium zirconium carbonate F2: sodium zirconium carbonate [silane coupling agent (G) having a glycidyl group]
G1: 3-glycidoxypropyltrimethoxysilane G2: 3-glycidoxypropyltriethoxysilane [nickel compound (I)]
I1: Nickel acetate I2: Nickel nitrate I3: Nickel sulfate

As the base steel plate of the surface-treated steel plate, the plated steel plate shown in Table 1 was used.
A surface treatment composition appropriately blended with the titanium-containing product liquid (A) and components (B) to (G) and (I) is applied to the surface of the plated steel sheet and dried at a predetermined drying temperature for 3 to 20 seconds. This was used as a test material. These test materials were evaluated for corrosion resistance and paint adhesion by the following test methods (1) and (2), and blackening resistance was evaluated by the following test method (4). Furthermore, the chemical stability of the surface treatment composition was evaluated by the following test method (3).
The results are shown in Tables 2 to 13 together with the composition of the surface treatment composition applied to each specimen and the coating conditions.

(1) Corrosion resistance A salt water spray test of JIS-Z-2371-2000 was performed on the specimens whose end portions and back surface were tape-sealed, and the test time at which the white rust generation area ratio was 5% was measured. The evaluation criteria are as follows.
◎: 240 hours or more ○: 144 hours or more, less than 240 hours Δ: 96 hours or more, less than 144 hours ×: less than 96 hours

(2) Adhesiveness of paint (2-1) Adhesion of primary paint Melamine alkyd resin (trade name “Delicon # 700”, manufactured by Dainippon Paint Co., Ltd.) with a dry film thickness is 30 on the pretreated specimen. It applied so that it might become +/- 2micrometer, and it baked for 30 minutes and dried at 130 degreeC. About this test material, the flat-plate part coating-material adhesiveness and the process part coating-material adhesiveness were evaluated, respectively. The pretreatment was performed under the following conditions.
Treatment liquid: Pulclean N364S (trade name, manufactured by Nihon Parkerizing Co., Ltd.), concentration 2%, 60 ° C
Treatment method: 2 minutes spray treatment (1 kgf / cm ² )
(2-1-1) Adhesiveness of flat plate paint Using a cutter knife on the coated surface, 11 lines were drawn vertically and horizontally at intervals of 1 mm, and 100 squares of 1 mm square were produced in a grid pattern. Then, cellophane adhesive tape (CT24, manufactured by Nichiban Co., Ltd.) is applied to the grid area, and according to the following “(2-3) Evaluation Criteria” according to the number of squares removed when this cellophane adhesive tape is peeled off. evaluated.
(2-1-2) Adhesiveness of processed part paint Using a cutter knife on the painted surface, 11 lines were drawn vertically and horizontally at intervals of 1 mm, and 100 squares of 1 mm square were produced in a grid pattern. After that, the grid section is extruded 5 mm with an Erichsen test machine, cellophane adhesive tape (CT24, manufactured by Nichiban Co., Ltd.) is applied to the grid section, and the cellophane adhesive tape is peeled off when the cellophane adhesive tape is peeled off. The evaluation was performed according to the following “(2-3) Evaluation Criteria”.

(2-2) Secondary paint adhesion Melamine alkyd resin (trade name “Delicon # 700”, manufactured by Dainippon Paint Co., Ltd.) is applied to the pre-treated specimen so that the dry film thickness is 30 ± 2 μm. Then, it was baked at 130 ° C. for 30 minutes and dried. This test material was immersed in boiling water for 2 hours, and thereafter, within 30 minutes, the flat part paint adhesion and the processed part paint adhesion were evaluated. The pretreatment was performed under the following conditions.
Treatment liquid: Pulclean N364S (trade name, manufactured by Nihon Parkerizing Co., Ltd.), concentration 2%, 60 ° C
Treatment method: 2 minutes spray treatment (1 kgf / cm ² )
(2-2-1) Flat Plate Paint Adhesiveness Using a cutter knife on the painted surface, 11 lines were drawn vertically and horizontally at intervals of 1 mm, and 100 squares of 1 mm square were produced in a grid pattern. Then, cellophane adhesive tape (CT24, manufactured by Nichiban Co., Ltd.) is applied to the grid area, and according to the following “(2-3) Evaluation Criteria” according to the number of squares removed when this cellophane adhesive tape is peeled off. evaluated.
(2-2-2) Paint adhesion of processed part Using a cutter knife on the painted surface, 11 lines were drawn vertically and horizontally at intervals of 1 mm, and 100 squares of 1 mm square were produced in a grid pattern. After that, the grid section is extruded 5 mm with an Erichsen test machine, cellophane adhesive tape (CT24, manufactured by Nichiban Co., Ltd.) is applied to the grid section, and the cellophane adhesive tape is peeled off when the cellophane adhesive tape is peeled off. The evaluation was performed according to the following “(2-3) Evaluation Criteria”.
(2-3) Evaluation Criteria ◎: No peeling ○: 1 to 5 squares out of 100 squares are peeled (number of remaining squares 99 to 95)
Δ: 6th to 50th cell out of 100th cell is peeled (number of remaining cells is 94 to 50)
X: The 51st-100th cell of the 100th cell peels (number of remaining cells 49-0)

(3) Chemical Solution Stability The surface treatment composition (H) having a predetermined composition was prepared as an aqueous solution having a solid content of 10% by mass, and the chemical solution state was observed when kept at 40 ° C. in a sealed state. According to the elapsed time until precipitation or gelation occurred, the evaluation was performed as follows.
A: No precipitation or gelation even after 2 weeks.
○: Over 1 week, precipitation or gelation within 2 weeks.
Δ: Precipitation or gelation within 3 days or more within 1 week.
X: Precipitation occurred or gelled within 2 days.
(4) Blackening resistance The surface treated surface of the same specimen (size: 150 mm x 150 mm) after being left in a stacked state for 28 days in an environment of 50 ° C and relative humidity of 98% or higher. The appearance was visually evaluated. The evaluation criteria are as follows. The evaluation of blackening resistance was No. Only for 169-173.
◎: No blackened portion ○: Lightly blackened portion that can be confirmed when viewed from an angle (less than 10% of the surface area)
Δ: There is a faint blackened area that can be confirmed from an oblique direction (10% or more of the surface area), or an obvious blackened area (less than 10% of the surface area).
×: Obvious blackening (10% or more of surface area)

In Tables 2, 4, 6, 8, 10, and 12, * 1 to * 10 indicate the following contents.
* 1 Plated steel sheets No. 1 to 10 listed in Table 1
* 2 Titanium-containing aqueous liquids T1 to T7 described in the specification text
* 3 Fluorine-containing compounds B1 to B4 described in the main text of the specification
* 4 Anionic urethane resins and anionic epoxy resins C1 to C8 described in the main text of the specification
* 5 Organophosphate compounds D1, D2 described in the main text of the specification
* 6 Vanadic acid compounds E1, E2 described in the main text of the specification
* 7 Zirconium carbonate compounds F1 and F2 described in the specification
* 8 Silane coupling agents G1, G2 described in the main text of the specification
* 9 Mass% of solid content in the surface treatment composition
* 10 Nickel compounds I1 to I3 described in the specification text

Claims (3)

At least one titanium selected from a hydrolyzable titanium compound, a hydrolyzable titanium compound low-condensate, titanium hydroxide, and a titanium hydroxide low-condensate on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet The titanium-containing aqueous liquid (A) obtained by mixing the compound with hydrogen peroxide water is 1 to 60% by mass in terms of the solid content, and the fluorine-containing compound (B) is 1 to 40% by mass in terms of the solid content. -Based urethane resin or / and anionic epoxy resin (C) at a solid content of 30 to 90% by mass, organophosphate compound (D) at a solid content of 1 to 60% by mass, vanadic acid compound (E) 0.1 to 30% by mass in terms of the solid content, 0.1 to 20% by mass in terms of the solid content of the zirconium carbonate compound (F), and the proportion of the silane coupling agent (G) having a glycidyl group as the solid content 1 to 0 wt% surface treatment composition containing (H) was applied, the film is formed by dry coverage of surface treatment characterized by having a surface treatment film of 0.2 to 3.0 g / m ² steel sheet.   The surface-treated steel sheet according to claim 1, wherein the fluorine-containing compound (B) is at least one selected from zircon ammonium fluoride and zircon hydrofluoric acid.   The surface-treated steel sheet according to claim 1 or 2, wherein the surface treatment composition (H) further contains 0.05 to 1 mass% of the nickel compound (I) in a solid content ratio.