JP2013060646A - Composition for spray coating surface treatment, method for producing surface-treated hot-dip galvanized steel sheet, and the surface-treated hot-dip galvanized steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environmentally compatible composition for surface treatment, which does not contain hexavalent chromium at all and can exhibit sufficient corrosion resistance and coating film appearance (finishing state) in the case when it is applied to the surface of a hot-dip galvanized steel sheet by a spray coating method to form a surface treatment coating film on the surface.SOLUTION: The composition for spray coating surface treatment includes: a specific titanium-containing aqueous liquid (A); a nickel compound (B); a fluorine-containing compound (C); an organic phosphoric acid compound (D); a vanadic acid compound (E); and a zirconium carbonate compound (F), by a prescribed amount each, has a pH within the range of 7-10, and contains no resin component. The composition is used for forming a surface treatment coating film by being applied to at least one surface of a hot-dip galvanized steel sheet by a spray coating method.

Description

  The present invention relates to a spray-coated surface treatment composition, a method for producing a surface-treated galvanized steel sheet, and a surface-treated galvanized steel sheet. In particular, the present invention relates to an environmentally-applicable surface treatment composition that does not contain hexavalent chromium and is suitable for being applied to the surface of a hot-dip galvanized steel sheet by a spray coating method.

  Conventionally, steel sheets for home appliances, steel sheets for building materials, and steel sheets for automobiles have been used for the purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of hot-dip galvanized steel sheets, chromic acid, dichromic acid or salts thereof Steel plates that have been chromate-treated with a treatment liquid containing as a main component are widely used. This chromate treatment is often performed by a spray coating method in a production line for hot dip galvanized steel sheets, and is economical. The spray coating method is a relatively simple method in which a chromate treatment solution is applied by spraying or is poured by a shower. Thereafter, the amount of coating (liquid film) is adjusted with a roll or an air squeezer and dried in an oven or the like.

  However, the chromate treatment uses hexavalent chromium, which is a pollution-controlling substance, and because of the environmental considerations and the waste liquid treatment of the chromate treatment liquid requires a great deal of labor and expense, the treatment liquid does not contain chromium. Chromate-free technology is being studied.

Here, when a treatment liquid not containing hexavalent chromium is applied to a hot dip galvanized steel sheet, the coating amount after drying needs to be about 1 g / m ² in order to develop corrosion resistance equivalent to or higher than that of chromate. It is difficult to obtain such a coating amount by the spray coating method. That is, in the spray coating method in which the liquid film is strongly squeezed with a roll or air after spraying, it is difficult to obtain a coating amount necessary for developing corrosion resistance. For this reason, in this case, it has been common to apply a treatment liquid to the surface of the steel sheet using a roll coating method and dry it to form a surface treatment film. This is because the roll coating method makes it relatively easy to adjust the coating amount by adjusting the rotational speed of the applicator roll and the pressing pressure between the rolls.

  Patent Document 1 uses a surface treatment composition in which a specific titanium-containing aqueous liquid, a nickel compound or / and a cobalt compound, and a fluorine-containing compound are blended at a predetermined ratio as a treatment liquid that does not contain hexavalent chromium. By applying this to a molten Zn-Al alloy-plated steel sheet by a roll coating method and drying it to form a surface treatment film, chromium has excellent corrosion resistance and blackening resistance, and also has excellent plating appearance. A technique for obtaining a free surface-treated molten Zn-Al alloy-plated steel sheet is described.

JP 2008-291350 A

  The roll coating method is suitable for accurately controlling the film thickness immediately after coating to several microns, but requires large-scale equipment such as a two-stage or three-stage backup roll, and requires capital investment. It becomes. Therefore, the present inventors applied the same composition as that of Patent Document 1 to the surface of a hot dip galvanized steel sheet using a spray coating method that is a conventional facility and can be applied with a simpler facility, and then dried. An attempt was made to form a treatment film and obtain the same characteristics as in Patent Document 1. However, when a surface treatment film was formed by spray coating for various compositions similar to Patent Document 1, foaming was observed in the liquid film immediately after coating when a part of the composition was coated, and then the film was dried. There was a problem that the appearance (finished state) of the formed surface treatment film was greatly impaired. Moreover, even when any of the above various compositions is applied, there is a problem that the spray coating method does not provide sufficient corrosion resistance to the steel sheet.

  Therefore, in view of the above problems, the object of the present invention is to provide sufficient corrosion resistance and coating appearance (finished state) even when a surface-treated coating is formed on the surface of a hot dip galvanized steel sheet by spray coating. Further, providing an environmentally-applicable surface treatment composition containing no hexavalent chromium, providing a method for producing a surface-treated hot-dip galvanized steel sheet using this composition, and the surface obtained by this method It is to provide a treated hot-dip galvanized steel sheet.

  When the present inventors further examined to achieve this object, when a composition containing a resin component in the composition described in Patent Document 1 was applied to the surface of a hot dip galvanized steel sheet by a spray coating method, It was found that foaming was observed in the liquid film. This is presumably because the resin component having a hydrophilic part and a hydrophobic part in the molecule is oriented at the liquid-gas interface, and the interfacial tension is lowered to stabilize the foam.

  In addition, the reason why the present inventors cannot obtain sufficient corrosion resistance by the spray coating method is that the liquid film is thicker than the roll coating method until it is sprayed by the spray coating method and then drawn by a ringer or the like. It came to the idea that it was because of the formation. That is, in the spray coating method, a thick liquid film is formed. Therefore, when an acidic and highly reactive treatment liquid such as the composition described in Patent Document 1 is used, etching on the surface of the hot dip galvanized steel sheet proceeds excessively. Therefore, a dense film cannot be formed, and sufficient corrosion resistance cannot be ensured.

  As a result, the surface of the hot dip galvanized steel sheet contains a specific titanium-containing aqueous liquid, nickel compound, fluorine-containing compound, organic phosphoric acid compound, vanadic acid compound, zirconium carbonate compound, in particular a fluorine-containing compound ratio within a certain range. In addition, if a composition having a pH adjusted within the range of 7 to 10 and containing no resin component is used, molten zinc having excellent corrosion resistance and coating appearance (finished state) that can be manufactured even with a simple equipment such as a spray coating method. It discovered that a plated steel plate was obtained and came to complete this invention.

This invention is made | formed based on such knowledge, The summary structure is as follows.
(1) Mixing at least one titanium compound selected from hydrolyzable titanium compounds, low-condensates of hydrolyzable titanium compounds, titanium hydroxide, and low-condensates of titanium hydroxide with hydrogen peroxide water The obtained titanium-containing aqueous liquid (A) is 10 to 60% by mass in the solid content ratio, the nickel compound (B) is 0.01 to 1% by mass in the solid content ratio, and the fluorine-containing compound (C) is solid. 10 to 20% by mass, 10 to 60% by mass of the organic phosphoric acid compound (D), and 0.1 to 30% by mass of the vanadic acid compound (E) to the solid content. And 5 to 30% by mass of the zirconium carbonate compound (F) in a solid content ratio,
pH is adjusted within a range of 7 to 10, and the composition does not contain a resin component,
A composition for spray coating surface treatment, which is used for forming a surface treatment film by applying to at least one surface of a hot dip galvanized steel sheet by a spray coating method.

  (2) The composition for surface treatment by spray application according to the above (1), wherein the fluorine-containing compound (C) is at least one selected from zircon ammonium fluoride and zircon hydrofluoric acid.

  (3) The spray coating surface treatment composition described in (1) or (2) above is applied to at least one surface of a hot dip galvanized steel sheet by a spray coating method, and the coating amount is reduced with a ringer roll or air and dried. A method for producing a surface-treated hot-dip galvanized steel sheet, characterized by forming a surface-treated film.

  (4) A surface-treated hot-dip galvanized steel sheet produced by the production method described in (3) above.

  According to the present invention, since the resin composition is not contained in the surface treatment composition, it is difficult to foam when applied by a spray coating method, and the appearance (finished state) of the surface treatment film obtained after drying is impaired. It will not be. Further, when the spray coating method is used by positively adjusting the pH of the composition to 7 to 10 and setting the fluorine-containing compound that greatly affects the reactivity to 10 to 20% by mass in the solid content ratio The reactivity with the steel sheet surface becomes an appropriate composition, and even a surface-treated film formed by coating by a spray coating method can provide sufficient corrosion resistance. In this way, there is absolutely no hexavalent chromium capable of exhibiting sufficient corrosion resistance and coating appearance (finished state) when applied to the surface of a hot dip galvanized steel sheet by spray coating to form a surface-treated coating. It was possible to provide a surface treatment composition having no environmental application.

  Hereinafter, the present invention will be described in more detail.

(Hot galvanized steel sheet)
The hot-dip galvanized steel sheet to which the composition for surface treatment of the present invention is applied is a steel sheet that has been subjected to hot-dip galvanizing of non-alloyed plating specified in JIS G 3302: 2010. This non-alloyed hot-dip galvanized steel sheet (hot-dip galvanized steel sheet) is suitable for the surface treatment composition of the present invention because of its oxide layer thickness and etchability. The surface-treated hot-dip galvanized steel sheet on which the surface-treated film is formed by spray-coating the treatment composition has excellent corrosion resistance. The steel type of the base steel plate is not particularly limited, and various steel plates such as low carbon steel, extremely low carbon steel, IF steel, and high tensile steel plates to which various alloy elements are added can be used.

  In order to prevent film defects and unevenness when the surface treatment film is formed on the surface of the plating film, alkali degreasing, solvent degreasing, surface adjustment treatment (alkaline surface adjustment treatment or Treatment such as acidic surface conditioning treatment can be performed.

  In addition, for the purpose of preventing blackening in the usage environment (a kind of oxidation phenomenon on the plating surface), an iron group metal ion (one or more kinds of Ni ion, Co ion, Fe ion) is previously applied to the plating surface as necessary. Surface conditioning treatment with an acidic or alkaline aqueous solution containing can also be performed.

(Method for forming surface treatment film)
In the present invention, the method of applying the surface treatment composition to the surface of the hot dip galvanized steel sheet is a spray coating method. Here, the “spray coating method” in the present specification means a method of spraying the surface treatment composition (treatment liquid) on the steel plate surface or a method of pouring it with a shower. Thereafter, the coating amount is squeezed with a ringer roll or air and dried to form a film on the surface of the steel sheet. Detailed conditions for coating will be described later.

(Composition for spray coating surface treatment)
In the composition for spray coating surface treatment of the present invention, the specific titanium-containing aqueous liquid (A) is 10 to 60% by mass in a solid content ratio, and the nickel compound (B) is 0.01 to 1 in a solid content ratio. 10% to 20% by mass of the fluorine-containing compound (C) in a proportion of the solid content, 10 to 60% by mass of the organophosphate compound (D) in the proportion of the solid content, and the vanadate compound (E). Containing 0.1 to 30% by mass of the solid content and 5 to 30% by mass of the zirconium carbonate compound (F) in the proportion of the solid content, the pH being adjusted within the range of 7 to 10; It is a composition containing no components, and this composition does not contain hexavalent chromium. By adopting such a composition, even if it is applied to the surface of a hot-dip galvanized steel sheet by a spray coating method, a surface-treated film exhibiting sufficient corrosion resistance and film appearance (finished state) can be obtained. This will be described in more detail below.

  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.).

As the hydrolyzable titanium compound containing a lower alkoxyl group as a hydrolyzable group, in particular, represented by the general formula Ti (OR) ₄ (wherein R represents the same or different alkyl group 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.

  The low condensate of the hydrolyzable titanium compound is a low condensate of the above hydrolyzable 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. This is because if the degree of condensation is 30 or less, a stable titanium-containing aqueous liquid can be obtained without causing white precipitation when mixed with hydrogen peroxide.

  The hydrolyzable titanium compounds listed above, low-condensates of hydrolyzable titanium compounds, titanium hydroxide, and low-condensates of titanium hydroxide can be used alone or in combination of two or more thereof. Tetraalkoxytitanium, which is a hydrolyzable titanium compound represented by the formula, is more preferred because precipitation hardly occurs when mixed with hydrogen peroxide.

  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 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 ortho-titanic acid thus precipitated is in a gel state polymerized by polymerization of OH or hydrogen bonds, and as such cannot be used as an aqueous liquid containing titanium. 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 produce peroxotitanium hydrate, and then the solution obtained by adding a basic substance is allowed to stand or be heated to allow peroxo 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 (hereinafter simply referred to as “hydrolyzable titanium compound a”) as the titanium compound is obtained by converting hydrolyzable titanium compound a to hydrogen peroxide. It can be obtained by reacting with 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 the 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 production method is partially three-dimensional by Ti—O—Ti bond, and the titanium-containing aqueous liquid (A) obtained by reacting this gel with hydrogen peroxide solution 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 liquid 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. The average particle diameter of the titanium oxide ultrafine particles contained in the titanium oxide dispersion thus produced is preferably 10 nm or less, more 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. 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).

  By applying and drying the surface treatment composition (G) containing the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a on the surface of the plated steel sheet (for example, heat drying at a low temperature), A dense titanium oxide-containing film (surface treatment film) having excellent adhesion can be formed.

  The heating temperature after applying the surface treatment composition (G) is, for example, preferably 200 ° C. or less, particularly preferably 150 ° C. or less. ) Of 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 (G). It is useful as a coating material for materials that cannot be heat-treated.

  Further, 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 an 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 (ii), (iii) Titanium oxide aggregates obtained by hydrolyzing or neutralizing titanium halide solutions such as titanium tetrachloride, etc. Amorphous titania sol dispersed in water or a sol in which the titanium oxide aggregate is fired to form anatase titanium fine particles and dispersed 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 CORPORATION, anatase crystal form, average particle diameter 6 nm), TA-15 (trade name, manufactured by NISSAN CHEMICAL CO., LTD., Anatase crystal form). STS-11 (trade name, manufactured by Ishihara Sangyo Co., Ltd., anatase type 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.

  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.

  Further, when the titanium-containing aqueous liquid (A1) is subjected to a heat treatment or autoclave treatment 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 performing heat drying at a low temperature, a dense titanium oxide-containing film (surface treatment film) having excellent adhesion can be formed.

  As the heating temperature after applying the surface treatment composition (H), if it dries, there is no problem. For example, the steel plate temperature is preferably 200 ° C. or less, particularly preferably 150 ° C. or less. An anatase-type titanium oxide-containing film containing a little 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 preferable to set it as 0.1-100 mass parts in conversion of hydrogen peroxide with respect to 10 mass parts, and it is more preferable to set it as 1-20 mass parts. If the blending ratio is 0.1 parts by mass or more, chelate formation is sufficient and cloudy precipitation does not occur. On the other hand, if it is 100 parts by mass or less, unreacted hydrogen peroxide hardly remains and is stored. It is preferable because it is difficult to release dangerous active oxygen.

  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.

  In order to ensure the stability of the treatment liquid, the content of the titanium-containing aqueous liquid (A) in the surface treatment compositions (G) and (H) is 10% by mass to 60% by mass in terms of solid content. And

  The nickel compound (B) is blended for improving blackening resistance, and examples of the nickel compound (B) include inorganic nickel compounds such as nickel acetate, nickel nitrate, and nickel sulfate. 1 type (s) or 2 or more types can be used. Of these, nickel acetate is preferred from the viewpoint of improving blackening resistance. The compounding quantity of a nickel compound (B) is 0.01 mass%-1 mass% in the ratio of the solid content of a composition. If the content is 0.01% by mass or more, sufficient blackening resistance can be improved, while if the content is 1% by mass or less, the corrosion resistance is not deteriorated.

  The fluorine-containing compound (C) is blended in order to improve storage stability, corrosion resistance, water resistance, and the like. Examples of the fluorine-containing compound (C) include zircon ammonium fluoride and zircon potassium fluoride. Inorganic fluorine-containing compounds such as zircon hydrofluoric acid, titanium ammonium fluoride, hydrofluoric acid, and ammonium hydrofluoride, and one or more of these can be used. Of these, it is preferable to use at least one selected from ammonium zircon fluoride and zircon hydrofluoric acid. Zirconium hydrofluoric acid is particularly suitable from the viewpoint of corrosion resistance after alkaline degreasing and adhesion to water, and zircon hydrofluoric acid from the viewpoint of corrosion resistance after alkaline degreasing.

  The compounding quantity of a fluorine-containing compound (C) is 10 mass%-20 mass% in the ratio of the solid content of a composition. If it is 10 mass% or more, the reactivity at the time of a spray process can be obtained appropriately, and sufficient corrosion resistance can be obtained. On the other hand, if the content is 20% by mass or less, the reactivity does not become too high, and the etching amount on the plating surface can be suppressed to obtain sufficient corrosion resistance.

  Examples of the organic phosphoric acid 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 compounding quantity of an organic phosphoric acid compound (D) is 10 mass%-60 mass% in the ratio of the solid content of a composition. If the amount of the organic phosphoric acid compound (D) is 10% by mass or more, sufficient storage stability can be obtained, and if it is 60% by mass or less, sufficient water resistance adhesion can be obtained.

  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. In order to ensure the corrosion resistance after alkali degreasing the film, the compounding amount of the vanadic acid compound (E) is 0.1% by mass to 30% by mass in terms of the solid content of the composition.

  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. In order to ensure the corrosion resistance after alkali degreasing the film, the blending amount of the zirconium carbonate compound (F) is 5% by mass to 30% by mass in terms of the solid content of the composition.

  The characteristic of the composition of this invention is that pH was adjusted in the range of 7-10. Where the composition containing only the components (A) to (F) is acidic, in the present invention, an alkali is further added to adjust the pH within the range of 7 to 10. In the case of the spray coating method, the liquid film thickness is thicker than that of the roll coating method after spraying until it is squeezed out by a ringer or the like. If the conditions are not adjusted, the reactivity with the steel sheet is too high, and the etching on the surface of the hot-dip galvanized steel sheet proceeds excessively, so that a dense film cannot be formed and sufficient corrosion resistance cannot be ensured. If the pH is within the range of 7 to 10 and the fluorine-containing compound is adjusted to an appropriate range, the reactivity with the steel sheet surface, that is, the etching property to the surface can be suppressed to an appropriate range, and sufficient corrosion resistance can be obtained. Can do.

  The alkali to be added is not particularly limited, and examples thereof include ammonia, sodium hydroxide, calcium hydroxide, dimethylamine, triethylamine, dimethylethanolamine, and ammonia is particularly preferable because it is volatilized in the drying process and hardly remains in the film. .

  Another feature of the composition of the present invention is that it does not contain a resin component. By not including the resin component in the surface treatment composition, foaming hardly occurs when applied by a spray coating method, and the appearance (finished state) of the surface treatment film obtained by subsequent drying is not impaired.

  In the composition of the present invention, if necessary, for example, etching agents such as silane coupling agents and inorganic phosphate compounds, heavy metal compounds other than the components defined by the present invention, thickeners, surfactants, dyes Etc. can be contained. Moreover, the composition of this invention can be diluted with hydrophilic solvents, such as methanol, ethanol, isopropyl alcohol, an ethylene glycol type solvent, a propylene glycol type solvent, for example as needed, and can be used.

(Surface-treated hot-dip galvanized steel sheet and manufacturing method thereof)
In the method for producing a surface-treated hot-dip galvanized steel sheet according to the present invention, at least one surface of a hot-dip galvanized steel sheet is coated with the composition described so far by a spray coating method, and the coating amount is squeezed with a ringer roll or air and dried. This can be obtained by forming a surface treatment film. As described above, the surface-treated hot-dip galvanized steel sheet thus obtained does not contain hexavalent chromium and exhibits sufficient corrosion resistance and appearance (finished state).

Next, the conditions of the spray coating method suitable for the present invention will be described. In the spray coating method, there is no problem if the spray pressure is such that the entire surface of the steel sheet is in contact with the liquid, and it is preferably 0.2 kgf / cm ² or more. This is because if it is less than 0.2 kgf / cm ^2, it is considered that appearance defects due to insufficient liquid are likely to occur. After spraying, squeeze the liquid with a ringer roll or air. The squeezing pressure of the ringer roll or the air pressure may be adjusted within a range in which a target adhesion amount can be obtained.

The adhesion amount per one side of the surface treatment film formed according to the present invention is preferably 0.05 to 0.5 g / m ² . If film coating weight of 0.05 g / m ² or more, it is possible to obtain a corrosion resistance more reliably, if 0.5 g / m ² or less, or cracking the film, the corrosion resistance and cracks are formed This is because the possibility of lowering is low.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to a following example at all.

(Plated steel sheet)
As the base steel plate of the surface-treated steel plate, the plated steel plate shown in Table 1 was used. No. Only 2 is a hot dip galvanized steel sheet used in the present invention example, and the rest is a galvanized steel sheet used in the comparative example.

(Surface treatment composition)
Below, each component (A)-(F) used for the composition of this Example is shown.
[Production of titanium-containing aqueous solution (A)]
<Production Example 1 (Titanium-containing aqueous liquid T1)>
Ammonia water (1: 9) 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 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 of tetraiso-propoxytitanium and 10 parts of iso-propanol was dropped into a mixture of 10 parts by weight of 30% by weight hydrogen peroxide and 100 parts by weight of deionized water with stirring at 20 ° C. over 1 hour. 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)>
A titanium-containing aqueous liquid T4 was obtained under the same production conditions as in Production Example 2 except that tetramer of tetraiso-propoxytitanium used in Production Example 2 was used instead of tetraiso-propoxytitanium.
<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.

[Nickel compound (B)]
B1: Nickel acetate B2: Nickel nitrate B3: Nickel sulfate

[Fluorine-containing compound (C)]
C1: Zircon ammonium fluoride C2: Zircon hydrofluoric acid C3: Zircon sodium fluoride C4: Zircon potassium fluoride

[Organic Phosphate Compound (D)]
D1: 1-hydroxymethane-1,1-diphosphonic acid D2: 1-hydroxyethane-1,1-diphosphonic acid

[Vanadate compound (E)]
E1: Ammonium metavanadate E2: Sodium metavanadate

[Zirconium carbonate compound (F)]
F1: Ammonium zirconium carbonate F2: Sodium zirconium carbonate

[Resin component (Z)]
Z1: Superflex E-2500 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., aqueous polyurethane resin, Tg: 42 ° C.)
Z2: Bayronal MD-1100 (trade name, manufactured by Toyobo Co., Ltd., water-based polyester resin)
Z3: Adeka Resin EM-0718 (trade name, ADEKA Co., Ltd., aqueous epoxy resin)
Z4: Hydran AP-10 (trade name, manufactured by Dainippon Ink & Chemicals, water-based polyurethane resin, Tg: 27 ° C.)
Z5: Hydran AP-30 (trade name, manufactured by Dainippon Ink and Chemicals, water-based polyurethane resin, Tg: 61 ° C.)
Z6: Hydran HW-340 (trade name, manufactured by Dainippon Ink & Chemicals, water-based polyurethane resin, Tg: 7 ° C.)
Z7: Hydran HW-350 (trade name, manufactured by Dainippon Ink & Chemicals, water-based polyurethane resin, Tg: 57 ° C.)
Z8: Superflex 110 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., water-based polyurethane resin, Tg: 46 ° C.)
Z9: Superflex 130 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., water-based polyurethane resin, Tg: 96 ° C.)
Z10: Superflex 600 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., water-based polyurethane resin, Tg: 70 ° C.)

[Alkali component]
Each composition of this example was adjusted to a pH described in Table 2 below by adding a predetermined amount of an aqueous ammonia solution.

A predetermined amount of these components was blended to prepare a plurality of types of surface treatment compositions. Table 2 shows the composition and pH of each composition. In Table 2, * 1 to * 9 indicate the following contents.
* 1 Titanium-containing aqueous solution T1 to T7 described in the specification text
* 2 Nickel compounds B1 to B3 described in the specification text
* 3 Fluorine-containing compounds C1 to C4 described in the main text of the specification
* 4 Organophosphate compounds D1 and D2 described in the specification text
* 5 Vanadic acid compounds E1, E2 described in the main text of the specification
* 6 Zirconium carbonate compounds F1 and F2 described in the specification text
* 7 Resin components Z1 to Z10 described in the specification text
* 8 Solid content ratio (mass%) in the surface treatment composition (aqueous treatment liquid)
* 9 pH value (measurement temperature 23 ° C)

(Application method)
The composition described in Table 2 was applied to the surface (one side) of any of the plated steel sheets described in Table 1 and dried at 30 to 100 ° C. to obtain test materials (surface-treated plated steel sheets). The coating was performed by the method shown below, and the coating amount per side was 0.2 g / m ² .
Application method 1: After the composition is applied by spraying at a spray pressure of 1 kgf / cm ² , excess liquid is squeezed out so that the liquid film thickness after squeezing with a Ringer roll is 2 μm.
Application method 2: The composition was applied by a roll coater, and each roll load was adjusted so that the liquid film thickness was 5 μm, and the composition was transferred to the steel sheet side.

(Evaluation criteria)
About each test material, the corrosion resistance and the finished state of the film were evaluated by the following test methods. In addition, blackening resistance, water adhesion resistance, and storage stability were also evaluated. The results are shown in Tables 3 and 4 together with the type of composition applied to each test material and the application conditions. In Tables 3 and 4, * 10 and * 11 indicate the following contents.
* 10 Coating method described in the text of the specification * 11 No. of plated steel sheet listed in Table 1. 1-8

(1) Corrosion resistance A salt spray test based on 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.
◎: 72 hours or more ○: 48 hours or more, less than 72 hours Δ: 24 hours or more, less than 48 hours ×: less than 24 hours

(2) Corrosion resistance (after degreasing)
After degreasing the specimen under the conditions described later, a salt spray test based on JIS-Z-2371-2000 is performed on the specimen with the end and the back tape sealed, and the white rust occurrence area ratio is The test time of 5% was measured. The evaluation criteria are as follows.
◎: 72 hours or more ○: 48 hours or more, less than 72 hours Δ: 24 hours or more, less than 48 hours ×: less than 24 hours [Degreasing conditions]
Degreasing agent “PARCLIN CLN-364S” (trade name, manufactured by Nihon Parkerizing Co., Ltd.) dissolved in water and adjusted to a concentration of 2% by mass and 60 ° C. is sprayed onto the test material for 2 minutes (spray) Pressure 1 kgf / cm ² ). Thereafter, the test material was washed with tap water for 30 seconds and dried by applying compressed air.

(3) Finished state of film The finished state of the film was determined according to the following criteria.
○ (good): Unevenness such as dry marks of bubbles is not visually confirmed, and the film is smooth and uniform with no film missing when rubbed with a finger.
Δ (slightly defective): Either unevenness is visually confirmed or the film is missing when rubbed with a finger.
X (defect): Concavities and convexities are confirmed visually, and a film is missing when rubbed with a finger.

(4) Blackening resistance The change in whiteness (L value) when the test material was allowed to stand in a thermo-hygrostat controlled at a temperature of 80 ° C. and a relative humidity of 95% for 24 hours was ΔL (L value after the test) -L value before test). The calculation standard is as follows.
○: ΔL ≧ −10
Δ: −10> ΔL ≧ −15
×: −15> ΔL

(5) Water-resistant adhesion Melamine alkyd resin paint (trade name: Delicon (registered trademark) # 700, manufactured by Dainippon Paint Co., Ltd.) was applied to the test material so that the dry film thickness was 30 μm ± 2 μm. Baking was performed at 0 ° C. for 30 minutes. The test material after baking was immersed in boiling water for 1 hour. After dipping, the specimen is pulled up, and 11 lines are drawn vertically and horizontally at a 1 mm interval on the painted surface to make 100 squares of 1 mm square in a grid pattern. A cellophane adhesive tape (trade name “CT-24”, manufactured by Nichiban Co., Ltd.) was applied to the grids in a grid pattern, and the number of squares from which the coating film was peeled after peeling the cellophane adhesive tape was evaluated.
○: No peeling of coating film ×: Occurrence of peeling

(6) Storage stability The composition adjusted to a concentration of 12% by mass was left in a constant temperature bath at 40 ° C. for 30 days, and the state of the composition was visually evaluated.
○: No change in the state of the composition is observed.
X: The composition has a viscosity increase or a gel insoluble matter is generated in the composition

  Table 3 and Table 4 show the following. First, as shown in Comparative Examples 14 to 39, when a surface treatment film was formed by a spray coating method using a composition having a pH outside the range of 7 to 10, the corrosion resistance was inferior. Moreover, when the pH was less than 7, that is, an acidic composition was used, the finish of the film was insufficient.

  Next, as shown in Comparative Examples 40 to 54, when a surface treatment film was formed by a spray coating method using a composition containing a resin component, the finished state of the film was deteriorated and the corrosion resistance was not sufficient.

  Furthermore, as shown in Comparative Examples 1 to 13, when any of the components (A) to (F) of the composition is out of the content range defined in the present invention, corrosion resistance, corrosion resistance after alkaline degreasing, At least one of blackening resistance, water adhesion resistance and storage stability was inferior.

  On the other hand, as shown in Invention Examples 1 to 34, when a surface treatment film is formed by a spray coating method using the composition included in the scope of the present invention, sufficient corrosion resistance and corrosion resistance after alkaline degreasing are obtained, and The finished state of the film was also good. Further, blackening resistance, water adhesion resistance and storage stability were sufficient.

  As shown in Comparative Examples 63 to 65 for reference, when the composition was applied by a roll coating method, the corrosion resistance was not inferior even if the composition was acidic with a pH of less than 7. Moreover, as shown in Comparative Examples 66 to 68 for reference, when applied by a roll coating method, the finish of the film was not inferior even if the composition contained a resin. From this, it was found that the problem that the corrosion resistance is inferior or the film finish is inferior is peculiar to the case of applying by the spray coating method.

  Further, as shown in Comparative Examples 55 to 61, sufficient corrosion resistance could not be obtained even when a composition satisfying the component composition defined in the present invention was applied to a steel sheet other than the hot dip galvanized steel sheet by a spray coating method. . Therefore, it turned out that this invention is peculiar when forming a surface treatment film | membrane with respect to a hot-dip galvanized steel plate with these compositions.

According to the present invention, hexavalent chrome capable of exhibiting sufficient corrosion resistance and coating appearance (finished state) when a surface-treated coating is formed on a surface of a hot dip galvanized steel sheet by spray coating. It was possible to provide an environmentally applicable surface treatment composition that does not contain the material.

Claims (4)

Titanium obtained by mixing at least one titanium compound selected from hydrolyzable titanium compounds, low-condensates of hydrolyzable titanium compounds, titanium hydroxide, and low-condensates of titanium hydroxide with hydrogen peroxide water 10 to 60% by mass of the aqueous solution (A) in the solid content, 0.01 to 1% by mass of the nickel compound (B) in the solid content, and the solid content of the fluorine-containing compound (C). 10 to 20% by mass, 10 to 60% by mass of the organic phosphoric acid compound (D) as a solid content, and 0.1 to 30% by mass of the vanadic acid compound (E) as a solid content, and carbonic acid. The zirconium compound (F) contains 5 to 30% by mass in a solid content ratio,
pH is adjusted within a range of 7 to 10, and the composition does not contain a resin component,
A composition for spray coating surface treatment, which is used for forming a surface treatment film by applying to at least one surface of a hot dip galvanized steel sheet by a spray coating method.   2. The spray-coated surface treatment composition according to claim 1, wherein the fluorine-containing compound (C) is at least one selected from zircon ammonium fluoride and zircon hydrofluoric acid.   The surface treatment film is formed by applying the spray coating surface treatment composition according to claim 1 or 2 to at least one surface of a hot dip galvanized steel sheet by a spray coating method, squeezing the coating amount with a ringer roll or air, and drying. A method for producing a surface-treated hot-dip galvanized steel sheet, wherein A surface-treated hot-dip galvanized steel sheet produced by the production method according to claim 3.