TWI463036B - Surface-treating composition and surface-treated steel sheet - Google Patents

Description

Surface treatment composition and surface treated steel sheet

The present invention relates to a surface treatment composition and a surface treatment steel sheet which are suitable for use in automobiles, home appliances, and building materials, and is an environmentally-compatible surface treatment composition which does not contain hexavalent chromium in a composition and a film, and a surface-treated steel sheet using the same. .

Steel sheets for home appliances, steel sheets for building materials, and steel sheets for automobiles have been widely used on the surface of zinc-based plated steel sheets or aluminum-based plated steel sheets for the purpose of improving corrosion resistance (white rust resistance and red rust resistance). Further, a chromic acid-treated steel sheet is applied to a treatment liquid containing chromic acid, dichromic acid or a salt thereof as a main component. This chromic acid treatment is an economical treatment method which is excellent in corrosion resistance and is relatively simple to carry out.

Although the chromic acid treatment is a hexavalent chromium using a pollution-restricting substance, the hexavalent chromium is treated by a closed system in the treatment step and the chromium is eluted from the chromate film due to the sealing action of the organic film formed by the upper layer. The probability is almost zero, so there is virtually no pollution to the human body or the environment due to hexavalent chromium. However, in recent years, as concerns about global environmental issues have increased, not only regulations that emphasize the past operating environment or drainage treatment, but also regulations that emphasize environmental load or environmental reconciliation have been established. Moreover, there is also an age background in which manufacturers are evaluated by environmental contribution, and the use of heavy metals containing hexavalent chromium is increasing.

Under these backgrounds, there are many proposals for white rust suppression technology (no chromate technology) of zinc-based plated steel sheets which do not use hexavalent chromium. For example, in Patent Documents 1 and 2, a surface treatment agent containing Al, a phosphoric acid compound, cerium oxide, and an aqueous organic resin emulsion, and a metal material coated therewith are proposed. Further, in Patent Document 3, a zinc-based plated steel sheet having an organic coating layer formed by applying a mixed aqueous solution of a dihydrogen phosphate of a polyvalent metal and a metal oxide sol and drying it to form an amorphous film is proposed. Further, in Patent Documents 4 and 5, a composite oxide film layer containing oxide fine particles and phosphoric acid and/or a phosphoric acid compound and one or more selected from the group consisting of Mg, Mn, and Al is proposed as a lower layer. The upper layer forms a steel sheet of an organic film.

In the use of zinc-based plated steel sheets, there are many parts that can withstand heating in a temperature range (about 500 to 600 ° C) above the melting point of zinc. For example, in the heat exchanger in the outdoor unit of the air conditioner, when the copper tube and the aluminum evaporator are welded, the zinc-based plated steel sheet is placed on the copper tube in order to prevent aluminum melting due to heating by the gas burner. Between the evaporator and the evaporator so that the flame of the burner does not directly contact the aluminum. When the surface-treated steel sheet of the above-described prior art is used for such an application, the organic resin main film is discolored into yellow or brownish brown due to thermal decomposition, resulting in poor appearance. For this reason, it is almost impossible to use a surface treated steel sheet of the prior art.

In order to solve these problems, a chromate-free technology having excellent heat discoloration resistance has been proposed. For example, in Patent Documents 6 and 7, an inorganic-rich film containing magnesium hydrogen phosphate, colloidal cerium oxide, and phosphonic acid as a main component is proposed. Further, in Patent Document 8, two layers of an inorganic-rich film mainly composed of dihydrogen phosphate and colloidal cerium oxide as a lower layer and a bismuth citrate film and/or a phthalic acid resin as an upper layer are proposed. Membrane. Further, Patent Document 9 discloses a surface treatment composition containing at least one selected from the group consisting of a low condensate of a hydrolyzable titanium compound, a hydrolyzable titanium compound, a titanium hydroxide, and a titanium hydroxide. A titanium-containing aqueous liquid, an organic phosphoric acid, a water-soluble or water-dispersible organic resin, a vanadate compound, a zirconium fluoride compound, and a zirconium carbonate compound obtained by mixing a compound with hydrogen peroxide water.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 11-350157

[Patent Document 2] JP-A-2000-26990

[Patent Document 3] JP-A-2000-129460

[Patent Document 4] JP-A-2002-53979

[Patent Document 5] JP-A-2002-53980

[Patent Document 6] JP-A-2000-79370

[Patent Document 7] JP-A-2001-348672

[Patent Document 8] JP-A-2004-91826

[Patent Document 9] JP-A-2006-9121

However, the inorganic-rich film of Patent Documents 6 and 7 has an extremely low degree of corrosion resistance, and it is difficult to use it as a substitute for the chromate film. On the other hand, although the two-layer film of Patent Document 8 can be used as a chromate film substitute, the degree of corrosion resistance can be used. However, since expensive tantalate or a tantalum resin is used, there is a problem in cost. Moreover, since the film obtained by these techniques is liable to be discolored into black in a humid environment (blackening), it is difficult to use in a heat exchanger which is easy to dew, and also generates a storage environment in which the product is conveyed. Restricted, not practical. Further, in the surface treatment composition of Patent Document 9, the fluoride contained in the composition can improve the water-resistant adhesion and the corrosion resistance after the alkali degreasing, but when the upper layer has a thick organic resin layer, the adhesion is lowered. The situation.

Further, the organic resin-coated steel sheet such as a coated steel sheet or a laminated steel sheet has an important property as an adhesive property of the organic resin layer. However, since the film obtained by the conventional phosphate treatment as a base treatment is crystalline, it is easy. The crystallization is destroyed by strict processing, and the adhesion of the organic resin layer is lowered. In particular, when a coated steel sheet or a laminated steel sheet having a thickness of the organic resin layer of 100 μm or more is used, the phosphoric acid film is damaged during the processing of the steel sheet, and the organic resin layer is easily peeled off from the starting point.

With respect to such problems, for example, in Patent Documents 3 to 5 which have been exemplified above, the plating metal on the substrate is reacted with the treatment liquid to form an extremely thin film of poorly soluble phosphate to exhibit corrosion resistance or paint adhesion. However, when such a surface-treated steel sheet is used for an organic resin-coated steel sheet, the adhesion or corrosion resistance during processing is also likely to be lowered. In particular, in the case of an organic resin-coated steel sheet having an organic resin layer having a thickness of 100 μm or more, in order to increase the film strength, a strong shear force is applied between the organic resin layer and the interface between the lower layer and the lower layer, and an organic resin layer is easily generated. Stripping.

In view of the above-mentioned problems of the prior art, the inventors of the present invention have previously proposed a surface treatment composition which is excellent in corrosion resistance, heat discoloration resistance, and blackening resistance, and which is obtainable and surface-receiving, as disclosed in Japanese Patent Application No. 2008-335387. The excellent adhesion of the organic resin layer formed on the upper layer of the film is treated, and in particular, excellent adhesion when the steel sheet having a thick organic resin layer having a thickness of 100 μm or more is deformed can be obtained. The surface treatment composition contains at least one titanium compound selected from the low condensate of the hydrolyzable titanium compound, the low condensate of the hydrolyzable titanium compound, the titanium hydroxide or the titanium hydroxide, and the hydrogen peroxide water in a specific ratio. The titanium-containing aqueous liquid, the zirconium carbonate compound, the organic phosphoric acid compound, the metal phosphate and the cerium oxide are obtained.

However, the inventors of the present invention have found that the film formed by the above surface treatment composition has a relatively brittle property, so that when the surface-treated steel sheet is manufactured by a real machine, the film is formed in contact with a metal roll or the like after the film is formed. It bites into the scar and has the problem that the corrosion resistance is easy to reduce.

Therefore, in order to solve the above problems, an object of the present invention is to provide a surface treatment composition and a surface-treated steel sheet which are completely free of hexavalent chromium and which are excellent in corrosion resistance, heat discoloration resistance and resistance change resistance. The blackness is excellent in scratch resistance when it is in contact with a metal roll or the like after the surface treatment film is formed, and is excellent in adhesion to the organic resin layer formed on the upper layer of the surface treatment film, and particularly has a thickness of 100 μm or more. The thicker organic resin layer also provides excellent adhesion when applied too harshly.

Further, another object of the present invention is to provide an organic resin-coated steel sheet using the surface-treated steel sheets.

The present inventors have examined the composition of the film which can solve the above-mentioned problems, and as a result, it has been found that a specific ratio is used for the surface of a metal material (preferably a zinc-based plated steel plate or an aluminum-based plated steel sheet). The titanium-containing aqueous liquid is compounded with a surface treatment composition of a zirconium carbonate compound, an organic phosphoric acid compound, a metal phosphate, a cerium oxide, and a water-soluble organic resin and/or a water-dispersible organic resin to form a surface-treated film, which can obtain excellent corrosion resistance and heat resistance. It has excellent discoloration resistance and blackening resistance, and is excellent in scratch resistance when it is in contact with a metal roll or the like after the surface treatment film is formed, and an organic resin layer can be formed on the surface of the surface treatment film, especially thicker having a thickness of 100 μm or more. The organic resin layer can also obtain excellent adhesion when subjected to excessively severe processing.

The present invention has been completed based on these findings, and the following is the gist of the present invention.

[1] A surface treatment composition characterized by being a titanium compound having at least one selected from the group consisting of a hydrolyzable titanium compound, a low condensate of a hydrolyzable titanium compound, a titanium hydroxide, and a titanium hydroxide. 100 parts by mass of the solid content of the titanium-containing aqueous liquid (A) obtained by mixing hydrogen peroxide water, containing 10 to 300 parts by mass of the zirconium carbonate compound (B) and 50 to 200 parts by mass of the organic phosphoric acid compound (C), and further containing a surface The metal phosphate (D) in a ratio of 5 to 20 mass% in the total solid content of the composition, the cerium oxide (E) in a ratio of 32 to 40 mass% in the total solid content of the surface treatment composition, and the total solid content of the surface treatment composition a water-soluble organic resin and/or a water-dispersible organic resin (F) in a proportion of 2 to 10 mass%.

[2] The surface treatment composition according to [1] above, wherein the cerium oxide (E) is a gas phase cerium oxide produced by a dry method.

[3] The surface treatment composition according to [2] above, wherein the gas phase cerium oxide has a surface density of 40 g/L or less.

[4] The surface treatment composition according to any one of the above [1] to [3] wherein the pH is from 7 to 12.

[5] A surface-treated steel sheet characterized in that it is coated on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and has a surface-treated composition according to any one of the above [1] to [4], which is dried. The formed film was deposited to a surface treatment of 0.03 to 0.5 g/m ² .

[6] An organic resin-coated steel sheet characterized in that the surface-treated film of the surface-treated steel sheet according to [5] above has an organic resin layer.

The surface-treated film formed by the surface-treating composition of the present invention has a high barrier property by being composed of a specific inorganic component, and therefore has excellent corrosion resistance and blackening resistance comparable to the chromate film, and It is not easy to produce excellent heat-resistant discoloration due to heating or color change. Further, when the surface-treated film is formed, it is excellent in scratch resistance when it comes into contact with a metal roll or the like, and an organic resin layer is formed on the surface of the surface-treated film, in particular, a thick organic resin layer having a thickness of 100 μm or more is applied too much. Excellent adhesion can also be obtained during severe processing.

Moreover, the surface-treated steel sheet and the organic resin-coated steel sheet of the present invention are excellent in corrosion resistance, blackening resistance, heat discoloration resistance, and scratch resistance, and the adhesion of the organic resin layer, particularly thick organic having a thickness of 100 μm or more. The resin layer is excellent in adhesion.

The surface treatment composition of the present invention comprises a titanium-containing aqueous liquid (A), a zirconium carbonate compound (B), an organic phosphoric acid compound (C), a metal phosphate (D), cerium oxide (E), and a water-soluble organic resin and/or Or water-dispersible organic resin (F). The surface treatment composition does not contain hexavalent chromium (except for hexavalent chromium which is an unavoidable impurity).

The titanium-containing aqueous liquid (A) is obtained by mixing a titanium compound selected from a hydrolyzable titanium compound, a low condensate of a hydrolyzable titanium compound, a low condensate of titanium hydroxide or titanium hydroxide, and hydrogen peroxide water. The obtained titanium-containing aqueous liquid.

The hydrolyzable titanium compound is a titanium compound having a hydrolyzable group directly bonded to titanium, and is formed by reacting with water such as water or steam to form titanium hydroxide. Further, the hydrolyzable titanium compound may be one in which all of the groups bonded to the titanium are hydrolyzable groups, or a part bonded to the titanium may be a hydrolyzable group.

The hydrolyzable group is not particularly limited as long as it is formed by reacting with water as described above, and examples thereof include a lower alkoxy group or a group forming a salt with titanium (for example, a halogen atom such as chlorine or hydrogen). Atom, sulfate ion, etc.).

As the hydrolyzable titanium compound containing a lower alkoxy group as a hydrolyzable group, it is particularly preferably represented by the formula Ti(OR) ₄ (wherein R represents the same or different alkyl group having 1 to 5 carbon atoms) Alkyl oxide. As the alkyl group having 1 to 5 carbon atoms, for example, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a second butyl group, a t-butyl group or the like can be exemplified.

As the hydrolyzable titanium compound having a group which forms a salt with titanium as a hydrolyzable group, titanium chloride, titanium sulfate or the like is exemplified as a representative example.

Further, the low condensate of the hydrolyzable titanium compound is a low condensate of the hydrolyzable titanium compound as described above. The low condensate may be a hydrolyzable group in which all of the groups bonded to the titanium are used, or a part which is a hydrolyzable group with a part bonded to the titanium.

The hydrolyzable titanium compound (for example, titanium chloride or titanium sulfate) in which the hydrolyzable group is a base of a salt with titanium is obtained by reacting an aqueous solution of a hydrolyzable titanium compound with an alkali solution such as ammonium or caustic soda. Titanic acid (titanium hydroxide sol) can also be used as a low condensate.

As the low condensate of the hydrolyzable titanium compound and the low condensate of the 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 preferably used. When the degree of condensation is 30 or less, a stable titanium-containing aqueous liquid can be obtained by mixing with hydrogen peroxide water.

The hydrolyzable titanium compound, the low condensate of the hydrolyzable titanium compound, the low condensate of the titanium hydroxide or the titanium hydroxide may be used alone or in combination of two or more. Among them, the hydrolyzable titanium represented by the above formula is preferable. The compound of titanium alkoxide. The reason for this is tetradecyl titanium oxide, and the alcohol formed during the hydrolysis is volatilized during the drying of the surface treatment composition, so that the film properties of the corrosion resistance and the like are not affected, and particularly excellent film properties can be obtained. .

The titanium-containing aqueous liquid (A) is a conventionally known titanium-containing aqueous liquid obtained by mixing the titanium compound and hydrogen peroxide water, and is not particularly limited. Specifically, the following can be exemplified.

(i) a titanate ion hydroperoxide complex or a titanic acid (peroxytitanate hydrate) aqueous solution obtained by adding hydrogen peroxide water to a gel or sol containing titanium hydroxide (refer to Japanese Patent Laid-Open No. 63-35419) Japanese Unexamined Patent Publication No. Hei 1-224220).

(ii) Hydrogen peroxide water is applied to a titanium hydroxide sol produced from an aqueous solution of titanium chloride or titanium sulfate and an alkaline solution, thereby synthesizing the liquid for forming a titanium oxide film (refer to Japanese Patent Laid-Open No. Hei 9-71418) Bulletin, Japanese Patent Laid-Open No. Hei 10-67516).

When the liquid for forming a titanium oxide film is obtained, hydrogen which is called orthotitanic acid is obtained by reacting an aqueous solution of titanium chloride or titanium sulfate having a base forming a salt with titanium with an alkali solution such as ammonia or caustic soda. Titanium oxide gel precipitated. Next, the titanium hydroxide gel is separated by decantation using water, sufficiently washed with water, and further hydrogen peroxide water is added, and a yellow transparent viscous liquid can be obtained by decomposing and removing excess hydrogen peroxide.

The precipitated orthotitanic acid is polymerized by OH or by hydrogen bonding, and cannot be directly used as a titanium-containing aqueous solution. When hydrogen peroxide is added to the gel, a part of OH becomes a peroxidized state, and becomes a sol state in which peroxytitanic acid ions are dissolved or the polymer chain is broken into low molecules, and excess hydrogen peroxide is decomposed into Water and oxygen can be used as the titanium-containing aqueous liquid for forming an inorganic film.

Since the sol contains only oxygen atoms and hydrogen atoms in addition to titanium atoms, when it is changed into titanium oxide by drying or baking, only water and oxygen are generated, so it is necessary for thermal decomposition such as gel sol method or sulfate method. It is not necessary to remove the carbon component or the halogen component, and a titanium oxide film having a higher density can be formed even at a low temperature.

(iii) adding hydrogen peroxide to an aqueous solution of an inorganic titanium compound of titanium chloride or titanium sulfate to form a titanium perotate hydrate, and then adding a solution obtained by adding a basic substance to form a titanium perotate hydrate polymer by standing or heating And a solution for forming a titanium oxide obtained by the action of hydrogen peroxide after removing at least the dissolved component derived from the water in the titanium-containing raw material solution (refer to JP-A-2000-247638, JP-A-2000-247638 Bulletin 2000-247639).

By using a hydrolyzable titanium compound and/or its low condensate (hereinafter referred to as "hydrolyzable titanium compound a" as a convenient description) as the titanium-containing aqueous liquid (A) of the titanium compound, the hydrolyzable titanium compound a can be used. It is obtained by reacting with hydrogen peroxide water at a reaction temperature of 1 to 70 ° C for 10 minutes to 20 hours.

The titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a is considered to cause the hydrolyzable titanium compound a to be hydrolyzed to form a hydroxyl group-containing titanium compound by reacting the hydrolyzable titanium compound a with hydrogen peroxide water. The hydrogen peroxide is coordinated to the hydroxyl group-containing titanium compound, and the hydrolysis reaction and the coordination with hydrogen peroxide are similarly obtained, and the stability is extremely high at room temperature and can withstand long-term preservation. Chelating solution. The titanium hydroxide gel used in the conventional method is partially ternary due to the Ti-O-Ti bond, and the gel reacts with hydrogen peroxide to have a composition and stability which is substantially different from the titanium-containing aqueous liquid (A). .

Moreover, when the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a is subjected to heat treatment or autoclave treatment at 80° C. or higher, a titanium oxide dispersion liquid containing ultrafine particles of crystallized titanium oxide is obtained. When the heat treatment or the autoclave treatment is carried out at 80 ° C or higher, crystallization of titanium oxide can be sufficiently performed. The titanium oxide ultrafine particles of the titanium oxide dispersion thus produced preferably have an average particle diameter of 10 nm or less, preferably about 1 to 6 nm. When the average particle diameter of the ultrafine titanium oxide particles is 10 nm or less, the film forming property is excellent (it is preferable since the film thickness is 1 μm or more without cracking when dried to a film thickness after application). Further, when the average particle diameter of the titanium oxide ultrafine particles is 1 nm or more, the viscosity of the surface treatment composition can be maintained at a low level, which is preferable. The titanium oxide dispersion has a translucent appearance. This titanium oxide dispersion can also be used as the titanium-containing aqueous liquid (A).

The surface-treated composition (H) containing the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a is applied to the surface of the plated steel sheet and dried (for example, dried at a low temperature) to form a dense one having excellent adhesion. A film containing titanium oxide (surface treated film).

The heating temperature of the steel sheet after the surface treatment composition (H) is applied is, for example, 200 ° C or lower, particularly preferably 150 ° C or lower, and by heating at these temperatures, an amorphous substance containing a plurality of hydroxyl groups can be formed (non- Crystalline) film of titanium oxide.

In addition, when the titanium oxide dispersion liquid obtained by heat treatment or autoclave treatment at 80 ° C or higher as described above is used as the titanium-containing aqueous liquid (A), the surface-treated composition (H) can be formed to form crystals. Since the film of titanium oxide is used, a coating material which is a material which cannot be heat-treated can be used.

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 titanium oxide fine particles and/or anatase-type titanium oxide fine particles are dispersed in water (if necessary, an aqueous organic solvent such as an alcohol-based or alcohol-ether-based solvent may be added). As the titanium oxide sol, a conventionally known one can be used. For example, titanium oxide aggregate obtained by hydrolyzing (i) a titanium-containing solution such as titanium sulfate or titanium sulfate, and (ii) an organic titanium such as titanium alkoxide can be used. a titanium oxide agglomerate obtained by hydrolysis of a compound, (iii) an amorphous titanium oxide sol obtained by dispersing a titanium oxide agglomerate such as a titanium oxide aggregate obtained by hydrolyzing or neutralizing a titanium halide solution such as titanium tetrachloride in water, or The titanium oxide agglomerate is fired to form an anatase-type titanium fine particle, which is dispersed in a sol in water.

When the amorphous titanium oxide is fired at a temperature higher than the crystallization temperature of the anatase, for example, at a temperature of 400 ° C to 500 ° C or higher, the amorphous titanium oxide can be converted into anatase titanium oxide. . As the aqueous sol of the titanium oxide, for example, TKS-201 (trade name, manufactured by TAYCA Co., Ltd., anatase crystal form, average particle diameter: 6 nm), TA-15 (trade name, manufactured by Nissan Chemical Co., Ltd., anatase) Mineral crystal form), STS-11 (trade name, manufactured by Ishihara Sangyo Co., Ltd., anatase crystal form).

In the titanium-containing aqueous liquid (A1), the mass ratio x/y of the titanium oxide sol x to the titanium hydrogen peroxide reactant y (the reaction product of the hydrolyzable titanium compound a and hydrogen peroxide water) is 1/99~ A range of 99/1, preferably about 10/90 to 90/10 is suitable. When the mass ratio x/y is 1/99 or more, the effect of adding a 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. Film formation is preferred.

The titanium-containing aqueous liquid (A1) can be obtained by reacting the hydrolyzable titanium compound a with hydrogen peroxide water at a reaction temperature of 1 to 70 ° C for 10 minutes to 20 hours in the presence of a titanium oxide sol.

The form of formation of the titanium-containing aqueous liquid (A1) or the characteristics thereof is the same as that of the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a described above, but in particular, by using a titanium oxide sol, a part of condensation during synthesis can be suppressed. The viscosity caused by the reaction. The reason for this is considered to be that the condensation reaction substance is adsorbed on the surface of the titanium oxide sol, and the polymerization in an easy state is suppressed.

Further, when the titanium-containing aqueous liquid (A1) is subjected to heat treatment at 80 ° C or higher or autoclave treatment, a titanium oxide dispersion liquid containing crystallized titanium oxide ultrafine particles can be obtained. The temperature conditions of the titanium oxide dispersion, the particle size of the crystallized titanium oxide ultrafine particles, the appearance of the dispersion, and the like are also the same as those of the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a as described above. This titanium oxide dispersion can also be used as the titanium-containing aqueous liquid (A1).

The surface-treated composition (G) containing the titanium-containing aqueous liquid (A1) is coated on a plated steel sheet and dried (for example, like the titanium-containing aqueous liquid (A) using the hydrolyzable titanium compound a as described above. In the case of heating at a low temperature, a dense titanium oxide-containing film (surface-treated film) excellent in adhesion can be obtained by itself.

The heating temperature of the steel sheet after the surface treatment composition (G) is applied is, for example, 200 ° C or lower, particularly preferably 150 ° C or lower, and by heating and drying at the same temperature, an anatase type containing a plurality of hydroxyl groups can be formed. A film of titanium oxide.

Further, as described above, in the titanium-containing aqueous liquid (A), the titanium-containing aqueous liquid (A) or the titanium-containing aqueous liquid (A1) using the hydrolyzable titanium compound a has excellent properties such as storage stability and corrosion resistance. It is preferred to use these in the present invention.

The ratio of the hydrogen peroxide water to at least one titanium compound selected from the group consisting of a hydrolyzable titanium compound, a low condensate of a hydrolyzable titanium compound, a titanium hydroxide, and a titanium hydroxide, is 10 parts by mass based on 10 parts by mass of the titanium compound. The hydrogen peroxide conversion meter is preferably from 0.1 to 100 parts by mass, more preferably from 1 to 20 parts by mass. When the ratio of the hydrogen peroxide is 0.1 parts by mass or more in terms of hydrogen peroxide, the chelating agent is formed so that no white turbid precipitate is formed. On the other hand, if it is 100 parts by mass or less, no unreacted remains. Hydrogen peroxide is preferred because it does not release active oxygen during storage.

The hydrogen peroxide concentration of the hydrogen peroxide water is not particularly limited, but is preferably about 3 to 30 mass% in terms of ease of handling and solid content of the liquid to be applied in terms of coating workability.

In the titanium-containing aqueous liquid (A), other sol or pigment may be added as needed. For example, commercially available titanium oxide sol or titanium oxide powder, mica, talc, cerium oxide, clay, or the like can be exemplified, and one or more of these may be added.

The content of the titanium-containing aqueous liquid (A) in the surface treatment composition is from 1 to 100 g/L, preferably from 5 to 50 g/L, in terms of solid content, and is preferable in terms of stability of the treatment liquid and the like.

The surface treatment composition of the present invention further improves the corrosion resistance by adding the zirconium carbonate compound (B) to the titanium-containing aqueous liquid (A), and can be hopped to improve the organic resin layer (organic formed by lamination or coating) The resin layer) is rust-proof once and coated with an organic resin layer before being coated. Further, the organic phosphoric acid compound (C) can improve the reactivity with the steel sheet to improve the corrosion resistance and at the same time improve the storage stability of the surface treatment composition. Further, by adding the metal phosphate (D) and the cerium oxide (E), the organic resin layer formed in the upper layer can be improved, in particular, a thick organic resin layer having a thickness of 100 μm or more (for example, by lamination). The organic resin layer) is adhered to the steel sheet during deformation. Further, by adding a water-soluble organic resin and/or a water-dispersible organic resin (F), the scratch resistance of the surface-treated film can be improved, and excellent corrosion resistance can be exhibited when the surface-treated film is brought into contact with the roll after formation. By.

As the zirconium carbonate compound (B), ammonium zirconium carbonate or zirconium oxycarbonate can be suitably used, and the corrosion resistance can be improved by using one or more of these. The amount of the zirconium carbonate compound (B) to be added is 10 to 300 parts by mass, preferably 50 to 100 parts by mass, per 100 parts by mass of the solid content of the carbonaceous aqueous liquid (A). When the amount of the zirconium carbonate compound (B) is less than 10 parts by mass based on 100 parts by mass of the solid content of the carbonaceous aqueous liquid (A), the effect of improving corrosion resistance is small. On the other hand, if it is more than 300 parts by mass, it is dense. The tendency to deteriorate.

As the organophosphorus compound (C), for example, 1-hydroxymethane-1,1-diphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxypropane-1,1 is exemplified as a suitable one. a hydroxyl group-containing organic phosphorous acid such as a diphosphonic acid; a carboxyl group-containing organic phosphorous acid such as 2-hydroxyphosphonium acetic acid or 2-phosphonium butane-1,2,4-tricarboxylic acid; and the like One or two or more of these may be used.

The organic phosphoric acid compound (C) has an effect of improving the corrosion resistance and the storage stability of the titanium-containing aqueous liquid (A). In particular, 1-hydroxyethane-1,1-diphosphonic acid has the greatest effect, and it is preferably used.

The amount of the organic phosphate compound (C) is preferably 50 to 200 parts by mass, and particularly 70 to 150 parts by mass, in terms of water resistance, and the like, in terms of the solid content of the titanium-containing aqueous liquid (A). . When the amount of the organic phosphate compound (C) is less than 50 parts by mass based on 100 parts by mass of the solid content of the titanium-containing aqueous liquid (A), the storage stability of the surface-treated composition is deteriorated, and the corrosion resistance is also lowered. On the other hand, when it exceeds 200 mass parts, water-resistant adhesion is inferior.

The metal phosphate (D) and the cerium oxide (E) are blended to improve the adhesion to the organic resin layer formed by lamination in the upper layer, especially the thick organic resin layer having a thickness of 100 μm or more. Examples of the cerium oxide (E) include, for example, liquid phase cerium oxide produced by a liquid phase reaction method, and amorphous cerium oxide such as a gas phase cerium oxide produced by a dry method. One or two of these may be used. More than one species. Specifically, as the liquid phase cerium oxide, SNOWTEX (registered trademark) O, N, 20, 30, 40, C, and S manufactured by Nissan Chemical Industries Co., Ltd. can be used, and as the gas phase cerium oxide, AEROSIL can be used in Japan. AEROSIL (registered trademark) 130, 200, 200V, 200CF, 300, 300CF, etc. manufactured by (share).

Particularly, the gas phase cerium oxide produced by the dry method is preferable from the viewpoint of adhesion to the organic resin layer, and good performance can be obtained.

Further, the type of the metal phosphate (D) is not particularly limited, and is particularly effective as an aluminum salt, a magnesium salt or a manganese salt. Especially in the case of aluminum salts, there is an advantage that the solubility of phosphate is low and the effect in a wet environment continues. One kind or two or more kinds of the above metal phosphates can be used. Further, as the metal phosphate (D), it is preferred to use a commercially available aqueous solution in which a phosphoric acid/metal cation component which is present in an aqueous solution is rich in phosphoric acid.

The metal phosphate (D) and cerium oxide (E) are added (formulated) to the surface treatment composition, and the metal phosphate (D) and cerium oxide (E) are preferably mixed in advance, and added as such a mixture. When the addition is added in a premixed state, it is more excellent in adhesion and corrosion resistance. Although this reason is not clear, it is considered that the film cohesive force obtained by the surface treatment composition is improved by the effect of the phosphoric acid component. Moreover, the storage stability of the surface treatment composition can be improved by mixing by this method.

Further, when cerium oxide (gas phase cerium oxide) produced by a dry method is used as the cerium oxide (E), a metal phosphate aqueous solution is prepared in advance by adding a gas phase cerium oxide to the aqueous metal phosphate solution and vigorously stirring the mixture. The cerium oxide dispersion in which the gas phase cerium oxide is dispersed is mixed with other components. Alternatively, the gas phase ceria and the metal phosphate aqueous solution may be strongly stirred together with other compounding ingredients and water to prepare a surface treatment composition.

In addition, when the gas phase cerium oxide is dispersed in the surface treatment composition by a sand mill or the like, aggregation occurs in about one week to several weeks, and a precipitate is formed. Although the detailed mechanism is not clear, it is judged that it is effective to use gas phase cerium oxide having a low apparent density insofar as it is less likely to cause such aggregation and improve storage stability (solution stability). Specifically, a gas phase cerium oxide having an apparent density of 40 g/L or less is preferably used. The apparent density of the gas phase ceria can be adjusted by controlling the degassing conditions after the dry process, whereby a gas phase ceria having a small apparent density can be obtained.

Increasing the adhesion to the organic resin layer by blending the metal phosphate (D) and the yttrium oxide (E) is considered to be due to the change in the surface polarity of the surface-treated film by blending cerium oxide and metal phosphate. The advantage of adhesion is beneficial. In order to increase the polarity of the ruthenium oxide, the organic resin layer is directly applied to the upper layer, and when the organic resin film is adhered through the adhesive, the adhesion between the resin layer and the adhesive layer is enhanced. On the other hand, if the polarity is too high, it is easy to obtain moisture in a humid environment, and it is relatively uncomfortable to expand. On the other hand, by blending non-polar phosphoric acid (metal phosphate), it is possible to achieve an appropriate surface polarity which can have both adhesion and stability at the time of wetting. Further, it is considered that cerium oxide is formed by sub-aggregation to form sub-micron-scale surface irregularities, and since the formation of such surface irregularities increases the effective area of the adhesion interface, it is effective for adhesion. The effect of blending metal phosphate on the structure is not fully understood, but it is believed to affect the organizer for the effect of secondary agglutination of yttrium oxide.

The ratio of the metal phosphate (D) to the total solid content of the surface treatment composition is 5 to 20 mass%, and the ratio of the cerium oxide (E) to the total solid content of the surface treatment composition becomes 32~40mass%.

When the ratio of the metal phosphate (D) to the total solid content of the surface treatment composition is less than 5 mass%, the effect is not exhibited, and the adhesion to the steel sheet is insufficient. On the other hand, when it is added in excess of 20 mass%, it is a factor that deteriorates performance such as blackening during storage before coating the organic resin layer.

When the proportion of the cerium oxide (E) is less than 32 mass% in the total solid content of the surface treatment composition, the formation of the submicron-scale unevenness is insufficient, and the organic resin with the upper layer cannot be obtained in the excessively severe processing. The layer is fully sealed. On the other hand, when it is more than 40 mass%, although good adhesion is obtained, since the surface-treated film becomes brittle, it will bite into the film by contact with the roll, and the bare corrosion resistance is of course scar-covered after the organic resin is coated. Corrosion occurs as a starting point, and expansion occurs.

The water-soluble organic resin and/or the water-dispersible organic resin (F) is an organic resin which can be dissolved or dispersed in water, and a conventionally known method can be used as a method of dissolving or dispersing the organic resin in water. Specifically, as the organic resin, a functional group containing a water-soluble or water-dispersible (for example, a hydroxyl group, a polyoxyalkylene group, a carboxyl group, an amine group (imino group), a thioether group, a phosphino group, etc.) may be used alone. And, if necessary, part or all of such functional groups, if it is an acidic resin (such as a carboxyl group-containing resin), an amine compound such as ethanolamine or triethanolamine; ammonia water; lithium hydroxide, sodium hydroxide, or hydroxide In the case of a basic resin (such as an amine group-containing resin), a fatty acid such as acetic acid or lactic acid or a neutralized inorganic acid such as phosphoric acid is used.

The water-soluble or water-dispersible organic resin is exemplified by, for example, an epoxy resin, a phenol resin, an acrylic resin, a urethane resin, an olefin-carboxylic acid resin, a nylon resin, and a polyoxyalkylene chain. Resin, polyvinyl alcohol, polyglycerin, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and the like. The above organic resins may be used alone or in combination of two or more.

In terms of storage stability of the surface treatment composition, it is preferable to use at least one selected from the group consisting of water-soluble or water-dispersible acrylic resins, urethane resins, and epoxy resins. In addition, it is preferable to use a water-soluble or water-dispersible acrylic resin or a urethane-based resin as a main component in terms of the balance between the storage stability of the surface-treated composition and the coating film performance.

The water-soluble or water-dispersible acrylic resin can be synthesized by a conventional method such as an emulsion polymerization method, a suspension polymerization method, a solution of a polymer having a hydrophilic group by solution polymerization, and a method of neutralizing and water-retaining as needed. obtain.

The polymer having a hydrophilic group can be obtained, for example, by polymerizing an unsaturated monomer having a hydrophilic group such as a carboxyl group, an amine group, a hydroxyl group, a polyoxyalkylene group, or the like, and optionally another unsaturated monomer.

The water-soluble or water-dispersible acrylic resin is preferably a copolymer of styrene in terms of corrosion resistance and the like, and the amount of styrene in all the unsaturated monomers is preferably from 10 to 60 mass%, preferably 15 ~50mass%. Further, the Tg (glass transition point) of the acrylic resin obtained by the copolymerization is preferably from 30 to 80 ° C, preferably from 35 to 70 ° C from the viewpoint of the toughness of the obtained film.

The carboxyl group-containing unsaturated monomer is exemplified by acrylic acid, methacrylic acid, maleic acid, maleic anhydride, crotonic acid, itaconic acid or the like.

The nitrogen-containing unsaturated monomer in the above-mentioned amino group-containing unsaturated monomer or the like is exemplified by N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylamine (meth)acrylate. Alkyl ester, nitrogen-containing alkyl (meth)acrylate such as N-t-butylaminoethyl (meth)acrylate; acrylamide, methacrylamide, N-methyl(meth)acryl Amine, N-ethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl ( Methyl) acrylamide, N,N-dimethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N,N-dimethylamino Polymer amides such as ethyl (meth) acrylamide; aromatic nitrogen-containing monomers such as 2-vinyl pyridine, 1-vinyl-2-pyrrolidone and 4-vinyl pyridine; allylamine and the like.

The hydroxyl group-containing unsaturated monomer is exemplified by 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2,3-dihydroxybutyl (meth)acrylate, and (meth)acrylic acid 4 a monoester compound of a polyvalent alcohol such as hydroxybutyl ester, polyethylene glycol mono(meth)acrylate or polypropylene glycol mono(meth)acrylate, and acrylic acid or methacrylic acid; in the above polyvalent alcohol with acrylic acid or nail A compound obtained by ring-opening polymerization of ε-caprolactone in a monoester compound of acrylic acid.

Other unsaturated monomers are exemplified by methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, Isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, (meth)acrylic acid Trialkyl ester, octadecyl (meth) acrylate, isobutyl methacrylate or the like, 1 to 24 alkyl (meth) acrylate, vinyl acetate, and the like.

The above-exemplified unsaturated monomers may be used alone or in combination of two or more. In the description of the present application, the term "(meth)acrylate" means "acrylate or methacrylate".

As the urethane-based resin, a polyurethane formed from a polyol such as a polyester polyol or a polyether polyol and a diisocyanate may be suitably used, for example, a diol, a diamine, or the like. In the case of a chain extender having a low molecular weight compound having two or more active hydrogens, the chain extender is stably dispersed or dissolved in water, and can be widely used in the past (see, for example, Japanese Patent Publication No. Sho 42-24192, Japanese Patent Publication No. Sho 42-24194, Japanese Patent Publication No. Sho 42-5118, Japanese Patent Publication No. Sho 49-986, No. Sho 49-33104, Japanese Patent Publication No. SHO-50-16027, Japanese Patent Publication No. Sho 53-29175.

The method of stably dispersing or dissolving the polyurethane resin in water can be, for example, the following method.

(1) A method in which a hydroxy group, an amine group, or an carboxy group is introduced into a side chain or a terminal of a polyurethane polymer to impart hydrophilicity, and is dispersed or dissolved in water by self-emulsification.

(2) Using a emulsifier and a mechanical shearing force to terminate the terminal isocyanate group by using the polyurethane resin or the terminal blocking agent such as hydrazine, alcohol, phenol, thiol, amine or sodium bisulfite. A method in which a polyurethane polymer is forcibly dispersed in water. Further, a method of mixing a urethane polymer having a terminal isocyanate group with water, an emulsifier, and a chain extender, and simultaneously performing dispersing and polymerizing using a mechanical shearing force.

(3) A method of dispersing or dissolving in water as a water-soluble polyurethane, using a water-soluble polyol such as polyethylene glycol as a polyol as a main raw material of a polyurethane.

Further, the polyurethane resin may be used in combination with a method different from the above dispersion or dissolution method.

The diisocyanate used for the synthesis of the above-mentioned polyurethane resin is exemplified by an aromatic, alicyclic or aliphatic diisocyanate, specifically, a hexamethylidene diisocyanate, a tetramethylidene diisocyanate, and 3 , 3'-dimethoxy-4,4'-biphenyl diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 1,3-(diisocyanate methyl)cyclohexanone, 1, 4-(Diisocyanatemethyl)cyclohexanone, 4,4'-diisocyanate cyclohexanone, 4,4'-methyl bis(cyclohexyl isocyanate), isophorone diisocyanate, 2,4 -toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, 2,4-naphthalene diisocyanate, 3,3'-di Methyl-4,4'-biphenyldiisocyanate, 4,4'-biphenyldiisocyanate, and the like. Among these, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate are preferable.

Commercial products of the polyurethane resin are Hydran (registered trademark) HW-330, Hydran HW-340, Hydran HW-350 (all trade names, manufactured by Dainippon Ink and Chemicals, Inc.), SuperFlex ( Registered trademark) 100, SuperFlex 150, SuperFlex E-2500, SuperFlex F-3438D (all trade names, manufactured by Daiichi Pharmaceutical Co., Ltd.).

As the epoxy resin, a cationic epoxy resin obtained by adding an amine to an epoxy resin, a modified epoxy resin such as an acrylic acid modification or a urethane modification, or the like can be suitably used. The cationic epoxy resin is exemplified by, for example, an adduct of an epoxy compound with a primary mono- or polyamine, a secondary mono- or polyamine, a first- or second-stage mixed polyamine (see, for example, U.S. Patent No. 3,984,299). An adduct of an epoxy compound with a secondary mono- or polyamine having a ketimine-grade amine group (see, for example, US Pat. No. 4017438); an epoxy compound and having a ketimine An etherification reaction product of a hydroxy compound of a primary amino group (see, for example, JP-A-59-43013).

The number average molecular weight of the epoxy resin is from 400 to 4,000, preferably from 800 to 2,000, and the epoxy equivalent is from 190 to 2,000, preferably from 400 to 1,000. The epoxy resin can be obtained, for example, by reacting a polyhydric phenol compound with epichlorohydrin, and the polyhydric phenol compound is exemplified by, for example, bis(4-hydroxyphenyl)-2,2-propane, 4,4-dihydroxybenzophenone. Ketone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-t-butylphenyl)-2 , 2-propane, bis(2-hydroxynaphthalene)methane, 1,5-dihydroxynaphthalene, bis(2,4-dihydroxyphenyl)methane, tetrakis(4-hydroxyphenyl)-1,1,2, 2-ethane, 4,4-dihydroxydiphenylphosphonium, phenol novolac resin, cresol novolak resin, and the like.

The ratio of the water-soluble organic resin and/or the water-dispersible organic resin (F) to the total solid content of the surface treatment composition is 2 to 10 mass%. When the ratio of the water-soluble organic resin and/or the water-dispersible organic resin (F) to the total solid content of the surface treatment composition is less than 2 mass%, the brittleness of the surface treatment film cannot be improved, and the surface treatment film is formed. After that, the contact with the roller may cause a bite to be trapped in the film, and the bare corrosion resistance is naturally etched after the organic resin is coated, and the scar portion is used as a starting point to swell. On the other hand, when it exceeds 10 mass%, heat-resistant discoloration property and adhesiveness after processing fall.

The pH of the surface treatment composition is preferably adjusted to 7-12. When the pH is less than 7 and exceeds 12, the film formation cannot be formed due to aggregation of the surface treatment composition over time.

The surface treatment composition of the present invention may further contain an etchant such as a decane coupling agent, a resin fine particle or an inorganic phosphate compound, a heavy metal compound other than the components specified in the present invention, a tackifier, a surfactant, and a lubricity imparting agent. Polyethylene wax, fluorine wax, carnauba wax, etc.), rust inhibitor, coloring pigment, body pigment, rust preventive pigment, dye, and the like. In particular, in order to improve the adhesion to the organic resin layer, a decane coupling agent is preferably contained.

Further, the surface treatment composition of the present invention may be diluted with a hydrophilic solvent such as methanol, ethanol, isopropanol, ethylene glycol solvent or propylene glycol solvent as needed.

The surface treatment composition of the present invention preferably has a solid content of about 2 to 10 mass% from the viewpoint of storage stability or stability at the time of coating.

The surface treatment composition of the present invention can be used as a surface treatment agent for various metal materials, but it is preferably used as a surface treatment agent for a zinc-based plated steel sheet or an aluminum-based plated steel sheet to be described later.

The surface-treated steel sheet of the present invention is coated with a surface treatment composition as described above on a surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, that is, containing a titanium-containing aqueous liquid (A), a zirconium carbonate compound (B), a surface treatment composition of an organic phosphoric acid compound (C), a metal phosphate (D), cerium oxide (E), and a water-soluble organic resin and/or a water-dispersible organic resin (F), and has a specific film formed by drying The amount of the surface is treated with a film. The surface treated film does not contain hexavalent chromium (except for hexavalent chromium which is an unavoidable impurity).

Further, the titanium-containing aqueous liquid (A) or the surface-treated composition may further contain other additional components listed above as needed.

As the zinc-based plated steel sheet which is the base of the surface-treated steel sheet of the present invention, for example, a zinc-plated steel sheet, a Zn-Ni alloy-plated steel sheet, or a Zn-Fe alloy-plated steel sheet (electroplated steel sheet, alloyed molten zinc plated steel sheet) can be used. ), Zn-Cr alloy plated steel plate, Zn-Mn alloy plated steel plate, Zn-Co alloy plated steel plate, Zn-Co-Cr alloy plated steel plate, Zn-Cr-Ni alloy plated steel plate, Zn-Cr- Fe alloy plated steel sheet, Zn-Al alloy plated steel sheet (for example, Zn-5mass% Al alloy plated steel sheet, Zn-55mass% Al alloy plated steel sheet), Zn-Mg alloy plated steel sheet, Zn-Al-Mg In the alloy-plated steel sheet, a zinc-based composite plated steel sheet (for example, a Zn-SiO ₂ dispersion-plated steel sheet) in which a metal oxide or a polymer is dispersed in the plating film of the plated steel sheet can be used. Further, in the above plating, a plurality of layers of plated steel sheets in which two or more layers of the same type or different types are plated may be used.

Further, as the aluminum-based plated steel sheet which is the basis of the surface-treated steel sheet of the present invention, an aluminum-plated steel sheet, an Al-Si alloy-plated steel sheet or the like can be used.

Further, the plated steel sheet may be formed by previously applying a thin basis weight such as Ni to the steel sheet surface, and applying the various platings as described above.

The plating method can be carried out by any method such as electrolysis (electrolysis in an aqueous solution or electrolysis in a nonaqueous solvent), a melting method, and a gas phase method.

In addition, when the surface treatment film is formed on the surface of the plating film so as not to cause film defects or unevenness, the surface of the plating film may be subjected to alkali degreasing, solvent deesterification, surface conditioning treatment (alkaline surface adjustment treatment or Acid surface conditioning treatment) and other treatments.

In addition, in order to prevent blackening in the use environment (one of the oxidation phenomenon of the plating surface), it is also possible to use the acidity of the iron-containing metal ions (one or more of Ni ions, Co ions, and Fe ions) on the plating surface as needed. Or an alkaline aqueous solution is subjected to a surface conditioning treatment.

When an electrogalvanized steel sheet is used as the lower steel sheet, iron group metal ions (one or more of Ni ions, Co ions, and Fe ions) may be added to the plating bath to prevent blackening, and the plating film may contain 1 These metals above mass ppm. In this case, the upper limit of the concentration of the iron group metal in the plating film is not particularly limited.

The adhesion amount of the surface treatment film formed of the surface treatment composition is 0.03 to 0.5 g/m ² . When the amount of adhesion of the film is less than 0.03 g/m ² , the corrosion resistance is poor. On the other hand, when the amount exceeds 0.5 g/m ² , the film is liable to be cracked, and when the organic resin is coated, the adhesion is deteriorated in the case of excessively severe processing.

The surface-treated steel sheet according to the present invention is formed by coating a surface-treating composition as described above on a surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, that is, containing a titanium-containing aqueous liquid (A) and a zirconium carbonate compound (B). After the surface treatment composition (treatment liquid) of the organic phosphoric acid compound (C), the metal phosphate (D), the cerium oxide (E), and the water-soluble organic resin and/or the water-dispersible organic resin (F), it is not washed with water. And dry.

Further, the titanium-containing aqueous liquid (A) or the surface-treating composition may further contain other additional components listed above as needed.

The coating means of the surface treatment composition (treatment liquid) is, for example, a spray cloth + a roll, a roll coater, or the like, and the drying method after application is also, for example, a hot air method, an induction heating method, or an electric furnace method. .

The drying temperature (steel plate temperature) of the surface-treated composition (treatment liquid) to be applied is preferably about 60 to 200 °C. When the drying temperature is 60° C. or higher, the formation of the film is sufficient, and the film is excellent in corrosion resistance. On the other hand, when the drying temperature is 200 ° C or lower, the film is not cracked by heat, so that a sufficient corrosion resistance improving effect can be obtained. Further, the drying temperature is preferably 60 to 140 ° C, more preferably 60 to 100 ° C.

Moreover, the organic resin-coated steel sheet of the present invention is an organic resin layer formed on the surface-treated film of the surface-treated steel sheet as described above. The method for forming the organic resin layer is arbitrary, and for example, a method of coating a ‧ dry coating composition, a method of laminating an organic resin film, or the like can be preferably used.

Further, the surface-treated film of the present invention is particularly excellent in adhesion to a thick organic resin layer having a thickness of 100 μm or more. Therefore, the organic resin-coated steel sheet of the present invention is particularly useful when the thickness of the organic resin layer is 100 μm or more.

Further, various additives typified by a non-chromium-based rust preventive additive, a solid lubricant, a coloring pigment, and the like can be blended in the organic resin layer.

[Example J

The titanium-containing aqueous liquid (A) and the components (B) to (F) used in the surface treatment composition are shown below. [Manufacture of titanium-containing aqueous liquid (A)]

‧Manufacturing Example 1 (titanium-containing aqueous solution T1)

Ammonia water (1:9 = ammonia: water mass ratio) was added dropwise to a solution of 5 cc of titanium tetrachloride 60 mass% solution in distilled water to 500 cc, and a low condensate of titanium hydroxide was precipitated. After washing with distilled water, a solution of 10 cc of hydrogen peroxide in water of 30 mass% was added and mixed to obtain a titanium-containing yellow translucent viscous titanium-containing aqueous liquid T1.

‧Manufacturing Example 2 (titanium-containing aqueous solution T2)

A mixture of 10 parts by mass of titanium tetraisopropoxide and 10 parts by mass of isopropyl alcohol was added dropwise to a mixture of 10 parts by mass of 30 mass% hydrogen peroxide water and 100 parts by mass of deionized water with stirring at 20 ° C for 1 hour. in. Subsequently, it was aged at 25 ° C for 2 hours to obtain a yellow transparent, less viscous titanium-containing aqueous liquid T2.

‧Manufacturing Example 3 (titanium-containing aqueous solution T3)

The titanium-containing aqueous liquid T3 was obtained in the same manner as in Production Example 2 except that tetra-n-butyl titanium oxide was used instead of the titanium tetraisopropoxide used in Production Example 2.

‧Manufacturing Example 4 (titanium-containing aqueous solution T4)

A titanium-containing aqueous solution was obtained in the same manner as in Production Example 2, except that a terpolymer of titanium isopropoxide (a low condensate of titanium tetraisopropoxide) was used instead of the titanium tetraisopropoxide used in Production Example 2. Liquid T4.

‧Manufacturing Example 5 (titanium-containing aqueous solution T5)

A titanium-containing aqueous liquid was obtained under the same manufacturing conditions as in Production Example 2, except that hydrogen peroxide water was used in the amount of three times that of Production Example 2, and the mixture was added dropwise at 50 ° C for one hour and then at 60 ° C for 3 hours. T5.

‧Manufacturing Example 6 (titanium-containing aqueous solution 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.

‧Manufacturing Example 7 (titanium-containing aqueous solution T7)

A mixture of 10 parts by mass of titanium tetraisopropoxide and 10 parts by mass of isopropyl alcohol was added dropwise to "TKS-203" (trade name, manufactured by Deca, titanium oxide sol) under stirring at 10 ° C for 1 hour. A mixture of parts by mass (solids), 30 mass% of hydrogen peroxide water, and 100 parts by mass of deionized water. Subsequently, it was aged at 10 ° C for 24 hours to obtain a yellow transparent, less viscous titanium-containing aqueous liquid T7.

[Zirconium compound (B)]

B1: ammonium zirconium carbonate

B2: zirconium oxycarbonate

B3: Zirconium ammonium fluoride

[Organic Phosphate Compound (C)]

C1:1-hydroxymethane-1,1-diphosphonic acid

C2: 1-hydroxyethane-1,1-diphosphonic acid

[Mixed metal phosphate (D) and cerium oxide (E) mixture]

The cerium oxide (E) is added to the aqueous solution of the metal phosphate (D) and vigorously stirred to obtain the cerium oxide dispersed in the metal phosphate by the solid proportions shown in Table 3, Table 5, Table 7, and Table 9. a mixture of brine solutions. Further, the comparative examples of No. 77 in Tables 7 and 8 contained only ruthenium oxide E4.

‧ metal phosphate (D)

D1: aluminum dihydrogen phosphate

D2: magnesium dihydrogen phosphate

D3: Manganese dihydrogen phosphate

‧Oxide (E)

E1: AEROSIL 300 (trade name, manufactured by Japan AEROSIL Co., Ltd., gas phase cerium oxide, apparent density; 50 g/L)

E2: AEROSIL 200 (trade name, manufactured by Japan AEROSIL Co., Ltd., gas phase cerium oxide, apparent density; 35 g/L)

E3: SNOWTEX O (trade name, manufactured by Nissan Chemical Industries Co., Ltd., colloidal cerium oxide)

E4: AEROSIL 300CF (trade name, manufactured by Japan AEROSIL Co., Ltd., gas phase cerium oxide, apparent density; 35 g/L)

[Water-soluble or water-dispersible organic tree (F)]

Among the water-soluble or water-dispersible organic resins, the water-dispersible acrylic resins of F1 to F5 are produced according to the production examples 8 to 12 shown below, and the commercial products of F6 to F13 are used. Moreover, the "parts" and "%" of the following manufacturing examples are the quality standards.

‧Manufacturing Example 8 (water-dispersible acrylic resin F1)

Adding 665 parts of deionized water, 9 parts of AQUALON RN-50 (Note 1), and AQUALON RN-2025 to a four-necked flask equipped with a reflux condenser, a stirrer, a thermometer, and a dropping funnel. 87 parts of the pre-emulsion of the monomer mixture 1 (first stage) having the following composition, which was forcedly emulsified, was 5% (28.9 parts), and after nitrogen substitution, the temperature was raised.

"Monomer Mix 1"

Deionized water 166.5 parts

AQUALON RN-50 6.6 copies

AQUALON RN-2025 53 servings

Styrene 35 parts

Methyl methacrylate 163.5 parts

105 parts of 2-ethylhexyl acrylate

5-hydroxyethyl methacrylate 5 parts

Methacrylic acid 3 parts

Acrylonitrile 38.5 parts

Third-dodecanethiol 1 part

After reaching 55 ° C or higher, 5% (4.43 parts) of an oxidizing agent aqueous solution obtained by dissolving 5 parts of Per-Butyl H (Note 3) in 83.5 parts of deionized water and 2.5 parts of sodium formaldehyde sulfonate in deionized water were added. 5% (4.3 parts) of an aqueous solution of a reducing agent in 83.5 parts, followed by raising the temperature and maintaining the temperature at 60 °C. After 15 minutes from the addition, the remaining pre-emulsion was added dropwise over 1.5 hours, the remaining aqueous oxidizing agent solution was added dropwise over 3.5 hours, and the remaining aqueous reducing agent solution was added dropwise over 3.5 hours. During the continuous dropwise addition of the aqueous oxidizing agent solution and the reducing agent aqueous solution, the monomer mixture 2 of the following composition was added dropwise over 1 hour after the first pre-emulsified liquid droplet addition was completed (second paragraph).

"Monomer Mix 2"

Styrene 15 parts

Methyl methacrylate 84.5 parts

22.5 parts of 2-ethylhexyl acrylate

4.25 parts of 2-hydroxyethyl methacrylate

Methacrylic acid 6 parts

Acrylonitrile 15 parts

Γ-methacryloxypropyltrimethoxydecane 2.75 parts

After the completion of all the dropwise addition, it was kept at a temperature of 60 ° C for 1 hour, and then the temperature was lowered to 40 ° C or less, 3.35 parts of 25% ammonia water, SURF EX (Note 4) 0.35 parts, 2, 2, 4-38 83.5 parts of 1,3-pentanediol monoisobutyrate, a water-dispersible acrylic resin F1 having a pH of 8.0 and a nonvolatile content of 31% was obtained.

(Note 1) AQUALON RN-50: trade name, manufactured by First Industrial Pharmaceutical Co., Ltd., nonionic emulsifier, solid content 60%

(Note 2) AQUALON RN-2025: trade name, manufactured by First Industrial Pharmaceutical Co., Ltd., nonionic emulsifier, 25% solids

(Note 3) PerButyl H: trade name, manufactured by Nippon Oil & Fats Co., Ltd., tert-butylperoxy peroxide, active ingredient 69%

(Note 4) SURF EX: Trade name, manufactured by EnviroChemicals, Japan, preservative

‧Manufacturing Example 9~12 (water-dispersible acrylic resin F2~F5)

In the production example 8, the water-dispersible acrylic resins F2 to F5 were obtained in the same manner as in Production Example 8 except that the monomer compositions of the first stage and the second stage were the mixing ratios shown in Table 2.

The characteristic values of each water-dispersible acrylic resin are shown together in Table 2.

F6: Super Flex E-2500 (trade name, manufactured by Daiichi Kogyo Co., Ltd., waterborne polyurethane resin)

F7: Super Flex 150 (trade name, manufactured by Daiichi Kogyo Co., Ltd., waterborne polyurethane resin)

F8: Super Flex 420 (trade name, manufactured by Daiichi Kogyo Co., Ltd., waterborne polyurethane resin)

F9: Super Flex 300 (trade name, manufactured by Daiichi Kogyo Co., Ltd., waterborne polyurethane resin)

F10: Vylonal MD-1100 (trade name, manufactured by Toyobo Co., Ltd., water-based polyester resin)

F11: ADEKA RESIN EM-0718 (trade name, manufactured by ADEKA Co., Ltd., waterborne epoxy resin)

F12: MODIPIX 303 (trade name, manufactured by Arakawa Chemical Industry Co., Ltd., waterborne epoxy resin)

F13: WATERSOL S-370 (trade name, manufactured by Dainippon Ink Chemical Industry Co., Ltd., waterborne epoxy resin)

The base steel sheets of the surface-treated steel sheets were the plated steel sheets shown in Table 1.

The titanium-containing aqueous liquid (A) is appropriately blended with the components (B) to (F) and distilled water, and the surface-treated composition having a solid content of 2 to 10 mass% and a pH adjusted to 8 is applied to the plating. On the surface of the steel sheet, after 5 seconds, it was dried to a specific drying temperature (up to the sheet temperature) to prepare a surface-treated steel sheet. The photocopying paper was wound on a rubber roller (48 mm Φ × 205 mm), and the surface of the rubbing film of the surface-treated steel sheet thus obtained was subjected to a scratch treatment with a load of 690 g (including the weight of the drum itself) without rotating the drum, and was used as the test material 1. Further, the comparative examples of No. 46 described in Tables 5 and 6 did not perform the above-described flaw treatment.

With respect to these samples 1, the heat-resistant discoloration, water-resistant adhesion, corrosion resistance, and blackening resistance were evaluated by the following test methods (1) to (4).

Next, a general vinyl chloride film was applied to the test material 1 with a dry film thickness of 3 μm, and then heated in a furnace at a furnace temperature of 100 ° C, followed by rolling a vinyl chloride film having a film thickness of 250 μm. The film was pressed against the surface of the test piece, and the organic resin-coated steel sheet (this is referred to as "test material 2") was produced by hot pressing with a vinyl chloride film (organic resin layer) so that the steel sheet temperature became 230 °C. The test material 2 thus produced was evaluated for the adhesion after the processing and the corrosion resistance by the following test methods (5) and (6).

Next, the storage stability of the surface treatment composition was evaluated by the following test methods (7) and (8).

The above results are shown in Tables 3 to 10 together with the composition of the surface treatment composition used for each of the test materials and the coating conditions thereof.

(1) Heat resistant discoloration

The test piece 1 was heated to a plate temperature of 500 ° C in an infrared image furnace for 30 seconds, and after holding for 30 seconds, the surface appearance upon natural cooling to room temperature was visually observed. The evaluation criteria are as follows.

○: no discoloration

△: turns yellowish

×: turns yellow to brown

(2) Water resistance

1 ml of pure water was added dropwise to the test piece 1, and the appearance of the surface was observed by visual observation in an oven at 100 ° C for 10 minutes. The evaluation criteria are as follows.

◎: No change

○: Almost no change

△: only the outline of the drip portion was observed.

×: All the drops are partially discolored

(3) Corrosion resistance

A test piece of 50 mm × 100 mm cut out from the test piece 1 was used, and the end portion and the back surface of the test piece were sealed, and a salt spray test of JIS-Z-2371-2000 was carried out to measure the area ratio of white rust to 5%. Test time. The evaluation criteria are as follows.

◎: 36 hours or more

○: More than 24 hours, less than 36 hours

△: 12 hours or more, less than 24 hours

×: less than 12 hours

(4) Resistance to blackening

The whiteness of the test material 1 in a constant temperature and humidity machine controlled to an atmosphere at a temperature of 80 ° C and a relative humidity of 95% was calculated by ΔL (L value after the test - L value before the test). L value) changes. The evaluation criteria are as follows.

○: △L≧-5.0

△: -5.0>△L≧-10.0

×:-10.0>△L

(5) Adhesiveness after processing (peeling strength after processing)

A test piece of 30 mm × 120 mm cut out from the test piece 2 was used, and two lines were drawn at right angles to the longitudinal direction at intervals of 50 mm in the substantially central portion of the longitudinal direction of the test piece, and the tensile tester was used. The jig clamped both ends in the longitudinal direction of the test piece and extended in the uniaxial direction until the interval between the two lines became 60 mm. Using the stretched test piece as a sample, a cut mark reaching the steel sheet was provided on the organic resin layer between the enlarged two lines so as to have a width of 20 mm. Forcibly peeling one end of the organic resin layer provided with the incision, clamping the end of the peeled organic resin layer with a jig of one of the tensile testing machines, and clamping the steel plate with the other jig of the tensile testing machine at a peeling speed A peel test was conducted under conditions of 50 mm/min. In the peeling test, the organic resin layer was peeled off from the steel sheet in the direction of 180 degrees (opposite direction), and the maximum strength (=peel strength) at the time of peeling was measured. The larger the peel strength, the more difficult it is to peel off the organic resin layer from the metal sheet, and the adhesion is excellent after bending or rolling. The post-process adhesion was evaluated based on the measured peel strength based on the following criteria.

◎: Peel strength is 40N/20mm or more

○: Peel strength is 30 N/20 mm or more, and is not 40 N/20 mm wide.

×: Peel strength is less than 30N/20mm wide

(6) Corrosion resistance (scratch resistance)

A 50 mm × 100 mm test piece cut out from the test piece 2 was used, and a cross cut was cut into the surface of the test piece, and a salt spray test was performed for 1,000 hours in accordance with JIS-Z-2371-2000. Determine the one-sided corrosion width from the cross cut. The evaluation criteria are as follows.

◎: The average corrosion width of the cut portion is less than 5mm

O: The average corrosion width from the cut portion is 5mm or more, less than 10mm

×: The average corrosion width from the cut portion is 10 mm or more

If the film formed on the surface of the surface-treated steel sheet is inferior in scratch resistance, the film is removed, and most of the flaws reaching the plating surface are formed. Since the scar portion does not have a film, it lacks adhesion to the organic resin layer, and water easily enters. Therefore, the salt water in the scar portion intrudes from the cross-cut portion and saturates to cause corrosion. As a result, in the case where the scratch resistance is poor, the etching width from the cross-cut portion becomes large. Therefore, the evaluation of the one-sided average corrosion width from the cross cut is an evaluation of the scratch resistance.

(7) Storage stability (I)

The surface treatment composition of 8 mass% of the solid content was subjected to 2 weeks at 40 ° C to visually evaluate the precipitation state and viscosity of the solid portion. The evaluation criteria are as follows.

◎: solid matter has no precipitation and no change in viscosity

○: only a small precipitate or a small viscosity change of the solid fraction

△: The solid part precipitates more or the viscosity changes greatly.

×: The solid part precipitates more and the viscosity changes greatly.

(8) Storage stability (II)

The surface treatment composition of 8 mass% of the solid content was kept at 30 ° C to visually evaluate the solid state precipitation state per week. The evaluation criteria are as follows.

◎: There is still no precipitation after 4 weeks.

○: precipitation occurs after 4 weeks

△: precipitation occurs after 2 weeks to 3 weeks

×: precipitation occurs after 1 week

In Table 3, Table 5, Table 7, and Table 9, *1 to *9 indicate the following.

*1 Plated steel sheets No.1 to No.9 as shown in Table 1.

*2 The titanium-containing aqueous liquid T1~T7 described in the manual.

*3 Zirconium compounds B1~B3 described in the specification

*4 The organic phosphate compounds C1 and C2 described in the manual.

*5 The metal phosphates D1~D3 described in the manual.

*6 The yttrium oxide E1~E4 described in the manual

*7 Instructions Water-soluble or water-dispersible organic resins F1~F13 described in this manual

*8 Surface treatment composition (aqueous treatment liquid) Solid mass in 1 liter (g)

*9 ratio of total solid content of the surface treatment composition (aqueous treatment liquid) (mass%)

Claims (5)

A surface treatment composition characterized by a titanium compound and hydrogen peroxide which are at least one selected from the group consisting of a hydrolyzable titanium compound, a low condensate of a hydrolyzable titanium compound, a titanium hydroxide, and a titanium hydroxide. 100 parts by mass of the solid content of the titanium-containing aqueous liquid (A) obtained by mixing water, containing 10 to 300 parts by mass of the zirconium carbonate compound (B), 50 to 200 parts by mass of the organic phosphoric acid compound (C), and further containing a surface treatment composition 5~20mass% of the total solid content of the metal phosphate (D), 32~40 mass% of the total solid content of the surface treatment composition of the cerium oxide (E), and the total solid content of the surface treatment composition 2~ a water-soluble organic resin and/or a water-dispersible organic resin (F) in a proportion of 10 mass%, and the pH of the aforementioned surface treatment composition exceeds 7 and is 12 or less. The surface treatment composition of claim 1, wherein the cerium oxide (E) is a gas phase cerium oxide produced by a dry method. The surface treatment composition of claim 2, wherein the gas phase cerium oxide has an apparent density of 40 g/L or less. A surface-treated steel sheet characterized by being coated on a surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and having a surface-treated composition according to any one of claims 1 to 3, which is formed by drying. The surface was treated with a film of 0.03 to 0.5 g/m ² . An organic resin-coated steel sheet characterized by having an organic resin layer on a surface-treated film of the surface-treated steel sheet according to claim 4.