JP2002275642A - Coated steel sheet excellent in corrosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a coated steel sheet which is subjected to rust preventive treatment with a chrome-free substrate treating agent to take place of chromic acid treatment and phosphate treatment and has excellent corrosion resistance. SOLUTION: This coated steel sheet having the excellent corrosion resistance is obtained by forming a film consisting of the substrate treating agent containing (A) an aqueous liquid containing at least one kind of a titanium compound selected from a hydrolyzable titanium compound, a low condensate of the hydrolyzable titanium compound, titanium hydroxide and a low condensate of the titanium hydroxide (B) at least one kind of a compound selected from a phosphoric acid-base compound, metal hydrofluoric acid and a metallic hydrofluorate and (C) an aqueous organic high-molecular compound stable at a pH <=7 on the surface of a substrate metallic material and forming a finish coating film through or without through a primer coating film on the surface treated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated steel sheet which has been subjected to rust-preventive treatment with a chromium-free undercoating agent in place of chromic acid treatment and phosphate treatment and has excellent corrosion resistance.

[0002]

2. Description of the Related Art Conventionally, chromate treatment and zinc phosphate treatment have been generally performed as surface treatments on metal substrates such as cold-rolled steel sheets, galvanized steel sheets, and aluminum steel sheets. Toxicity is a problem. The chromate treatment has a problem of volatilization of chromate fume in the treatment process, a large cost for wastewater treatment equipment, and a problem of elution of chromate from the chemical conversion coating. Hexavalent chromium compounds are available from IARC (Internat
Many official institutions, including the ional Agency for Researchon Cancer Review, have designated it as a carcinogen for the human body and are extremely harmful.

[0003] In the zinc phosphate treatment, after the zinc phosphate treatment, a rinsing treatment with chromic acid is usually performed, so that there is a problem of the chromium treatment, and a reaction accelerator in the zinc phosphate treatment agent, and waste water such as metal ions. There is a problem of sludge treatment due to elution of metal ions from the treated and treated metal.

As treatment methods other than chromate treatment and zinc phosphate treatment, there are (1) a surface treatment method of treating with an aqueous solution containing aluminum biphosphate and then heating at a temperature of 150 to 550 ° C. -28857), (2)
A method of treating with an aqueous solution containing tannic acid (JP-A-51
And (3) a treatment method using sodium nitrite, sodium borate, imidazole, an aromatic carboxylic acid, a surfactant, or a combination thereof.

[0005] However, the method (1) has a problem in that when the paint is applied thereon, the adhesion of the paint is not sufficient, the method (2) has poor corrosion resistance, and the method (3) has a problem.
All have the problem that the corrosion resistance when exposed to a hot and humid atmosphere is poor.

Further, as a zinc-based steel sheet having a thin film having a thickness of several μm or less, Japanese Patent Application Laid-Open Nos.
JP-A-60-50179 and JP-A-60-50180 disclose a method in which a zinc-based plated steel sheet is used as a base material, a chromate film is formed thereon, and an organic composite silicate film is further formed thereon as an uppermost layer. Rusted steel sheets are known, and have excellent performance in workability and corrosion resistance. However,
Since this rust-preventive steel sheet has a chromate film, there is a problem of safety and health due to chromate ions as described above. Further, the steel sheet obtained by removing the chromate film from the rust-proof steel sheet still has insufficient corrosion resistance.

Further, in the phosphate treatment, a phosphate compound not involved in the film formation precipitates as sludge, and it is necessary to dispose this sludge as industrial waste, and there are problems such as environmental measures and disposal costs. .

An object of the present invention is to provide a coated steel sheet having excellent corrosion resistance, which has been subjected to a rust-preventive treatment with a chromium-free undercoating agent in place of chromic acid treatment and phosphate treatment.

[0009]

DISCLOSURE OF THE INVENTION The present inventors have selected, as a metal rust inhibitor, an aqueous liquid containing a specific titanium, a phosphoric acid compound, a metal hydrofluoric acid, and a metal hydrofluoride. The present inventors have found that a coated steel sheet using at least one compound and an undercoating agent prepared by blending an aqueous organic polymer compound achieves the above object, and completed the present invention.

Thus, according to the present invention, at least one selected from the group consisting of (A) a hydrolyzable titanium compound, a hydrolyzable titanium compound low condensate, titanium hydroxide and a titanium hydroxide low condensate is formed on the surface of the base metal material. Aqueous solution containing titanium obtained by reacting a kind of titanium compound with aqueous hydrogen peroxide, (B) at least one compound selected from phosphoric acid compounds, metal hydrofluoric acid and metal hydrofluoride And (C) a film made of an undercoating agent characterized by containing an aqueous organic polymer compound stable at pH 7 or less, and overcoated with or without an undercoating film on the undercoated film. A coated steel sheet having a film and excellent in corrosion resistance is provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The coated steel sheet of the present invention is characterized in that an undercoating film with a specific undercoating agent is formed on the surface of an undercoat metal material instead of a chromic acid treatment or a phosphate treatment. By forming an overcoat film on or without the undercoat film on the undercoat film, a coated steel sheet having excellent corrosion resistance can be obtained.

First, the undercoating agent will be described.

The surface treatment agent used in the present invention is at least one compound selected from the group consisting of aqueous liquid (A) containing titanium, phosphoric acid compound, metal hydrofluoric acid and metal hydrofluoride. (B) and an aqueous organic polymer compound (C).

Aqueous liquid containing titanium (A) The aqueous liquid containing titanium (A) used in the undercoating agent is
Aqueous solution containing titanium obtained by reacting at least one titanium compound selected from a hydrolysable titanium compound, a hydrolysable titanium compound low-condensate, titanium hydroxide and a titanium hydroxide low-condensate with hydrogen peroxide water. Liquid. The aqueous liquid is not particularly limited as long as it is as described above, and a conventionally known aqueous liquid can be appropriately selected and used.

The above-mentioned 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 steam. In the hydrolyzable titanium compound, all of the groups bonded to titanium may be hydrolyzable groups, or one part thereof may be a hydrolyzed hydroxyl group.

The hydrolyzable group is not particularly limited as long as it produces titanium hydroxide by reacting with water as described above. For example, a lower alkoxyl group or a group which forms a salt with titanium (for example, , A halogen atom (eg, chlorine), a hydrogen atom, a sulfate ion, etc.).

As the hydrolyzable titanium compound containing a lower alkoxyl group as a hydrolyzable group, a compound represented by the general formula Ti (OR) ₄ (wherein R is the same or different and represents an alkyl group having 1 to 5 carbon atoms) ) 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. No.

Typical hydrolyzable titanium compounds having a group capable of forming a salt with titanium as a hydrolyzable group include titanium chloride and titanium sulfate.

The hydrolyzable titanium compound low condensate is a low condensate of the above hydrolyzable titanium compounds. The low-condensate may be either a group in which all of the groups bonded to titanium are hydrolyzable or a part of which is a hydrolyzed hydroxyl group.

Ortho-titanic acid (titanium hydroxide gel) obtained by reacting an aqueous solution of titanium chloride or titanium sulfate with an alkaline solution such as ammonia or caustic soda can also be used as a low condensate.

The degree of condensation in the above low-condensation product of the hydrolyzable titanium compound or titanium hydroxide is 2 to 30.
As the aqueous liquid (A), it is preferable to use a compound having a condensation degree in the range of 2 to 10,
As long as it is an aqueous liquid containing titanium obtained by reacting the above-described titanium compound with aqueous hydrogen peroxide, a conventionally known aqueous liquid can be used without particular limitation.
Specifically, the following can be mentioned.

A titanyl ion hydrogen peroxide complex or an aqueous solution of titanic acid (peroxotitanium hydrate) obtained by adding aqueous hydrogen peroxide to a gel or sol of hydrous titanium oxide (JP-A-63-35419 and JP-A-1 -224220).

Liquids for forming a titania film obtained by reacting an aqueous solution of hydrogen peroxide on a titanium hydroxide gel produced from an aqueous solution of titanium chloride or titanium sulfate and a basic solution (Japanese Patent Application Laid-Open Nos. -67516).

In the above liquid for forming a titania film, an aqueous solution of titanium chloride or titanium sulfate having a group capable of forming a salt with titanium is reacted with an alkali solution such as ammonia or caustic soda to form a hydroxide called orthotitanic acid. Precipitate the titanium gel. Subsequently, the titanium hydroxide gel is separated by decantation using water, washed well with water, and further added with hydrogen peroxide solution to decompose and remove excess hydrogen peroxide, whereby a yellow transparent viscous liquid can be obtained.

The precipitated orthotitanic acid is in a gel state polymerized by polymerization of OH and hydrogen bonds, and cannot be used as an aqueous liquid containing titanium as it is. When hydrogen peroxide solution is added to this gel, a part of OH becomes a peroxidized state and dissolves as peroxotitanate ions, or it becomes a kind of sol in which the polymer chain is divided into low molecules, and excess peroxidation occurs. Hydrogen is decomposed into water and oxygen to be used as an aqueous liquid containing titanium for forming an inorganic film.

Since this sol contains only oxygen atoms and hydrogen atoms in addition to titanium atoms, when it is converted into titanium oxide by drying or firing, only water and oxygen are generated, so it is necessary for the sol-gel method and thermal decomposition of sulfates and the like. It is not necessary to remove a carbon component or a halogen component, and a crystalline titanium oxide film having a relatively high density can be formed even at a lower temperature than before.

Hydrogen peroxide is added to an aqueous solution of an inorganic titanium compound such as titanium chloride or titanium sulfate to form peroxotitanium hydrate, and a basic substance is added thereto. After a precipitate of the titanium hydrate polymer is formed, at least a dissolved component other than water derived from the titanium-containing raw material solution is removed, and a solution for forming titanium oxide obtained by further reacting with hydrogen peroxide (particularly, Kai 2000-247638 and JP 2000-247639
Reference).

As the aqueous liquid (A) used in the present invention, an aqueous liquid containing titanium obtained by the above-mentioned known method can be used. In addition, a method of producing the aqueous liquid by adding a titanium compound to a hydrogen peroxide solution. The aqueous liquid containing titanium obtained by the above can be used. The titanium compound contains a group which is hydrolyzed by the general formula Ti (OR) ₄ (where R is the same or different and represents an alkyl group having 1 to 5 carbon atoms). It is preferable to use a hydrolyzable titanium compound or a low-condensate of the hydrolyzable titanium compound.

The mixing ratio of the hydrolyzable titanium compound and / or a low-condensate thereof (hereinafter, these are simply referred to as “hydrolyzable titanium compound a”) and the hydrogen peroxide solution are as follows. It is preferably in the range of 0.1 to 100 parts by weight, particularly 1 to 20 parts by weight in terms of hydrogen peroxide, based on 10 parts by weight of a. If the amount is less than 0.1 part by weight in terms of hydrogen peroxide, chelate formation is not sufficient and cloudy precipitation occurs.
On the other hand, if it exceeds 100 parts by weight, unreacted hydrogen peroxide is apt to remain, and dangerous active oxygen is released during storage.

The hydrogen peroxide concentration of the aqueous hydrogen peroxide solution is not particularly limited, but is preferably in the range of 3 to 30% by weight in view of the ease of handling and the solid content of the product liquid related to coating workability.

The aqueous liquid (A) using the hydrolyzable titanium compound a is prepared by reacting the hydrolyzable titanium compound a with a hydrogen peroxide solution at a reaction temperature of 1 to 70 ° C. for 10 minutes to 20 minutes.
It can be produced by reacting for hours.

The aqueous liquid (A) using the hydrolyzable titanium compound a is prepared by reacting the hydrolyzable titanium compound a with a hydrogen peroxide solution, whereby the hydrolyzable titanium compound is hydrolyzed with water. It is presumed that a hydroxyl group-containing titanium compound is generated, and then hydrogen peroxide is coordinated to the generated hydroxyl group-containing titanium compound, and a product obtained by this hydrolysis reaction and coordination by hydrogen peroxide occurring at the same time. And a chelating solution having extremely high stability at room temperature and enduring long-term storage is produced. The titanium hydroxide gel used in the conventional manufacturing method is partially three-dimensionalized by Ti-O-Ti bonds, and is essentially different in composition and stability from a product obtained by reacting this gel with a hydrogen peroxide solution.

When the 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 containing crystallized ultrafine titanium oxide particles is obtained. If it is lower than 80 ° C., crystallization of titanium oxide does not proceed sufficiently. In the titanium oxide dispersion thus produced, the particle diameter of the ultrafine titanium oxide particles is 10 nm or less, preferably in the range of 1 nm to 6 nm. The appearance of the dispersion is translucent. When the particle diameter is larger than 10 nm, the film forming property is reduced (1 μm).
m or more), which is not preferable. This dispersion can likewise be used.

The aqueous liquid (A) comprising the hydrolyzable titanium compound a is applied to a steel sheet material and dried or heat-treated at a low temperature to form a dense titanium oxide film having excellent adhesion by itself. it can.

As the heat treatment temperature, it is preferable to form the titanium oxide film at a temperature of, for example, 200 ° C. or less, particularly 150 ° C. or less.

The aqueous liquid (A) using the hydrolyzable titanium compound a forms an amorphous titanium oxide film containing a small amount of hydroxyl groups at the above-mentioned temperature.

Further, a titanium oxide dispersion liquid which has been subjected to a heat treatment at 80 ° C. or higher can form a crystalline titanium oxide film only by coating, and thus is useful as a coating material of a material which cannot be subjected to a heat treatment.

In the present invention, as the aqueous liquid (A), a hydrolyzable titanium compound and / or a low-condensate of a hydrolyzable titanium compound and hydrogen peroxide water in the presence of a titanium oxide sol are further used. An aqueous liquid containing titanium obtained by the reaction (hereinafter, abbreviated as "aqueous liquid (A-1)") can be used. As the hydrolyzable titanium compound and / or the low-condensate of the hydrolyzable titanium compound (hydrolysable titanium compound a), the above-mentioned general formula Ti (OR)
₄ (wherein R is the same or different and represents an alkyl group having 1 to 5 carbon atoms), a titanium monomer containing a group that becomes a hydroxyl group by hydrolysis and a low-condensate of the hydrolyzable titanium compound. It is preferred to use.

In the above-mentioned titanium oxide sol, amorphous titania and anatase-type titania fine particles contain water (if necessary,
For example, a sol dispersed in an aqueous organic solvent such as an alcohol-based or alcohol-ether-based solvent may be used.

As the above-mentioned titanium oxide sol, a conventionally known one can be used. Examples of the titanium oxide sol include (1) those obtained by hydrolyzing a titanium-containing solution such as titanium sulfate or titanyl sulfate;
Titanium oxide aggregates such as those obtained by hydrolyzing an organic titanium compound such as titanium alkoxide and (3) those obtained by hydrolyzing or neutralizing a titanium halide solution such as titanium tetrachloride are dispersed in water. Amorphous titania sol or anatase type titanium fine particles obtained by firing the titanium oxide aggregates and dispersing them in water can be used. Amorphous titania can be converted to anatase-type titania by firing at least at a temperature higher than the crystallization temperature of anatase, for example, at a temperature of 400 ° C. to 500 ° C. or higher. As an aqueous sol of the titanium oxide, for example, TKS-201 (manufactured by Teica Co., Ltd., trade name, anatase crystal form, average particle diameter 6n)
m), TA-15 (manufactured by Nissan Chemical Co., Ltd., trade name, anatase type crystal form), STS-11 (manufactured by Ishihara Sangyo Co., Ltd., trade name, anatase type crystal form) and the like.

The weight ratio of the titanium oxide sol to the titanium hydrogen peroxide reactant when used for reacting the hydrolyzable titanium compound a with aqueous hydrogen peroxide is 1/99 to 9
9/1, preferably in the range of about 10/90 to 90/10. When the weight ratio is less than 1/99, the effect of adding titanium oxide sol such as stability and photoreactivity is not seen, and 99/1
Exceeding the range is not preferred because the film-forming properties are poor.

The mixing ratio of the hydrolyzable titanium compound a and the aqueous hydrogen peroxide is 0.1 to 100 parts by weight, particularly 1 to 20 parts by weight in terms of hydrogen peroxide, based on 10 parts by weight of the hydrolyzable titanium compound a. Is preferably within the range. If the amount is less than 0.1 part by weight in terms of hydrogen peroxide, chelate formation is not sufficient and cloudy precipitation occurs. On the other hand, if it exceeds 100 parts by weight, unreacted hydrogen peroxide is apt to remain, and dangerous active oxygen is released during storage.

The hydrogen peroxide concentration of the aqueous hydrogen peroxide solution is not particularly limited, but is preferably in the range of 3 to 30% by weight in view of the ease of handling and the solid content of the product liquid related to coating workability.

The aqueous liquid (A-1) is prepared by reacting the hydrolyzable titanium compound a with aqueous hydrogen peroxide at a reaction temperature of 1 to 70 ° C. for 10 minutes to 20 hours in the presence of a titanium oxide sol. Can be manufactured.

The aqueous liquid (A-1) reacts the hydrolyzable titanium compound a with aqueous hydrogen peroxide to hydrolyze the hydrolyzable titanium compound a with water to form a hydroxyl group-containing titanium compound. Next, it is presumed that hydrogen peroxide is coordinated to the generated hydroxyl group-containing titanium compound, and the hydrolysis reaction and the coordination by hydrogen peroxide occur at the same time, resulting in stability at room temperature. Produces a chelating solution that is extremely high and can withstand long-term storage. The titanium hydroxide gel used in the conventional manufacturing method is Ti-OT
The gel is partially three-dimensionalized by i-bonds, and the gel and the hydrogen peroxide solution are essentially different in composition and stability. In addition, by using the titanium oxide sol, it is possible to prevent a partial condensation reaction from occurring during the synthesis to increase the viscosity. It is considered that the reason for this is that the condensation reaction product is adsorbed on the surface of the titanium oxide sol, thereby preventing polymerization in a solution state.

Further, the aqueous liquid (A-1) containing titanium was
When a heat treatment or an autoclave treatment is carried out at 0 ° C. or more, a titanium oxide dispersion containing crystallized ultrafine particles of titanium oxide is obtained. If it is lower than 80 ° C., crystallization of titanium oxide does not proceed sufficiently. In the titanium oxide dispersion thus produced, the particle diameter of the ultrafine titanium oxide particles is 10 nm or less, preferably in the range of 1 nm to 6 nm. The appearance of the dispersion is translucent. The particle size is 10
If it is larger than nm, the film-forming property is deteriorated (breakage occurs at 1 μm or more), which is not preferable. This dispersion can likewise be used.

The aqueous liquid (A-1) containing titanium is applied to a steel sheet material by drying or heat treatment at a low temperature, whereby
By itself, a dense titanium oxide film having excellent adhesion can be formed.

It is preferable to form the titanium oxide film at a temperature of, for example, 200 ° C. or lower, particularly 150 ° C. or lower.

The aqueous liquid (A-1) containing titanium forms an anatase-type titanium oxide film containing a small amount of hydroxyl groups at the above-mentioned temperature.

As the aqueous liquid (A) of the present invention, the aqueous liquid and the aqueous liquid (A-1) using the hydrolyzable titanium compound a have excellent properties such as storage stability and corrosion resistance. Preferably, one is used.

In the aqueous liquid (A) containing titanium, other pigments and sols can be added and dispersed as needed. Examples of the additives include commercially available titanium oxide sol, titanium oxide powder, and the like, mica, talc, silica, barita, clay, and the like.

Compound (B) The compound that is the component (B) of the undercoating agent is at least one compound selected from phosphoric acid compounds, metal hydrofluoric acids, and metal hydrofluorides.

Examples of the phosphoric acid compounds include phosphorous acid, strong phosphoric acid, triphosphoric acid, hypophosphorous acid, hypophosphoric acid,
Monophosphoric acids such as trimetaphosphoric acid, diphosphoric acid, diphosphoric acid, pyrophosphoric acid, pyrophosphoric acid, metaphosphoric acid, metaphosphoric acid, phosphoric acid (orthophosphoric acid), and phosphoric acid derivatives, and salts thereof, and tripolyphosphoric acid , Tetraphosphoric acid, hexaphosphoric acid, condensed phosphoric acids such as condensed phosphoric acid derivatives, and salts thereof. These compounds can be used alone or in combination of two or more. Also,
Examples of the alkali compound forming the above-mentioned salt include organic or inorganic alkali compounds such as lithium, sodium, potassium, and ammonium. further,
It is preferable to use a water-soluble phosphoric acid compound.

Examples of the phosphate compound include sodium pyrophosphate, sodium tripolyphosphate, sodium tetraphosphate, metaphosphoric acid, ammonium metaphosphate,
It is preferable to use sodium hexametaphosphate, since sodium hexametaphosphate and the like exhibit excellent effects such as storage stability of the coating agent and rust prevention of the coating film.

In the present invention, the above-mentioned blend of the aqueous liquid (A) containing titanium and the phosphate compound is prepared by coordinating the acidic phosphate group ion bound to the phosphate compound with the titanium ion. It is considered that a complex structure is formed between the two.

Such a reaction can be easily carried out by simply mixing the two components. For example, by leaving the mixture at room temperature (20 ° C.) for about 5 minutes to about 1 hour, When forcibly heating, for example, heating can be performed at about 30 to about 70 ° C. for about 1 minute to about 30 minutes.

The above-mentioned metal hydrofluoric acid and metal hydrofluoride include, for example, zirconium hydrofluoric acid, titanium hydrofluoric acid, hydrosilicofluoric acid, zirconium fluoride, titanium fluoride, Examples thereof include silicofluoride. Examples of the metal hydrofluoric acid salt include, for example, sodium, potassium, lithium, and ammonium. Among them, potassium and sodium are preferable, and specific examples thereof include potassium zirconium fluoride, potassium titanium fluoride, Examples thereof include sodium silicofluoride and potassium silicofluoride.

The phosphoric acid compound, the metal hydrofluoric acid and the metal hydrofluoride can be used singly or in combination of two or more. The compounding ratio of the compound (B) is based on the aqueous liquid containing titanium. The amount is preferably from 1 to 400 parts by weight, particularly preferably from 10 to 200 parts by weight, based on 100 parts by weight of the solid content of (A).

The aqueous organic high molecular compound (C) is treated with the aqueous organic high molecular compound (C) in addition to the above components. The aqueous organic polymer compound (C) itself is free from aggregation and sedimentation of the organic resin component dissolved or dispersed in water at a pH of 7 or less, and does not cause thickening or abnormal gelation. Any conventionally known aqueous liquid can be used as long as the aqueous liquid has excellent stability.

The aqueous organic polymer compound (C) is water-soluble,
Those having a form of water dispersibility or emulsion can be used. Water soluble organic polymer compound in water,
As a method of dispersing and emulsifying, a conventionally known method can be used. In particular,
As the organic polymer compound, a compound containing a functional group (for example, at least one kind of a hydroxyl group, a carboxyl group, an amino (imino) group, a sulfide group, a phosphine group, etc.) which can be made water-soluble or water-dispersible by itself, and if necessary. When some or all of these functional groups are acidic resins (such as carboxyl group-containing resins), amine compounds such as ethanolamine and triethylamine; ammonia water; lithium hydroxide;
Those neutralized with an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, or a basic resin (such as an amino group-containing resin), a fatty acid such as acetic acid or lactic acid; A sum can be used.

Examples of the aqueous organic polymer compound (C) include an epoxy resin, a phenol resin, an acrylic resin, a urethane resin, an olefin-carboxylic acid resin, a nylon resin, and a polyoxyalkylene chain. Resins, polyvinyl alcohol, polyglycerin, carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose and the like can be mentioned.

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-modified or urethane-modified resin can be preferably used. As a cationic epoxy resin,
For example, an adduct of an epoxy compound with a primary mono- or polyamine, a secondary mono- or polyamine, a mixed primary and secondary polyamine, and the like (for example, U.S. Pat.
No. 99); an adduct of an epoxy compound and a secondary mono- or polyamine having a ketiminated primary amino group (see, for example, U.S. Pat. No. 4,017,438); And etherification reaction products with a hydroxyl compound having a secondary amino group (for example, see JP-A-59-43013).

The epoxy compound has a number average molecular weight of 4
In the range of from 0.00 to 4,000, in particular from 800 to 2,000, and the epoxy equivalent is in the range from 190 to 2,000, in particular 4
Those in the range of 00 to 1,000 are suitable. Such an epoxy compound can be obtained, for example, by reacting a polyphenol compound with epilurylhydrin. Examples of the polyphenol compound include bis (4-hydroxyphenyl) -2,2-propane,
4-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butylphenyl) -2,2-propane ,
Bis (2-hydroxynaphthyl) methane, 1,5-dihydroxynaphthalene, bis (2,4-dihydroxyphenyl) methane, tetra (4-hydroxyphenyl)-
Examples thereof include 1,1,2,2-ethane, 4,4-dihydroxydiphenylsulfone, phenol novolak, and cresol novolak.

As the above-mentioned phenolic resin, those obtained by making a polymer compound obtained by heating and adding and condensing a phenol component and formaldehyde in the presence of a reaction catalyst soluble in water can be suitably used. As the phenol component as a starting material, a bifunctional phenol compound, a trifunctional phenol compound, a phenol compound having four or more functional groups, and the like can be used. For example, as the bifunctional phenol compound, o-cresol, As trifunctional phenol compounds such as p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, and 2,5-xylenol, phenol, m-cresol, m-ethylphenol, 3,5-
Bifunctional phenol compounds such as xylenol and m-methoxyphenol include bisphenol A and bisphenol F. These phenol compounds can be used alone or in combination of two or more.

Examples of the acrylic resin include a homopolymer or a copolymer of a monomer having a hydrophilic group such as a carboxyl group, an amino group, and a hydroxyl group, and a copolymer of a monomer having a hydrophilic group with another monomer. And copolymers with possible monomers. These are resins obtained by emulsion polymerization, suspension polymerization or solution polymerization, and, if necessary, neutralized and made aqueous or modified resins.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, crotonic acid, and itaconic acid.

Examples of the nitrogen-containing monomer include nitrogen-containing alkyl (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and Nt-butylaminoethyl (meth) acrylate. ) Acrylate; acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide,
N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N
Polymerizable amides such as -dimethylaminoethyl (meth) acrylamide; 2-vinylpyridine, 1-vinyl-2-
Aromatic nitrogen-containing monomers such as pyrrolidone and 4-vinylpyridine; and allylamine.

As the hydroxyl group-containing monomers, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2,3-dihydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth)
Acrylate and polyethylene glycol mono (meth)
Monoesters of polyhydric alcohols such as acrylates with acrylic acid or methacrylic acid; compounds obtained by ring-opening polymerization of ε-caprolactone with monoesters of the polyhydric alcohols with acrylic acid or methacrylic acid, and the like.

Other monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl C1-C24 such as (meth) acrylate, 2-ethylhexyl acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, octadecyl (meth) acrylate, and isostearyl (meth) acrylate; Alkyl (meth) acrylate; styrene, vinyl acetate and the like. These compounds can be used alone or in combination of two or more. In the present invention, “(meth) acrylate” means acrylate or methacrylate.

As the urethane resin, a polyurethane composed of a polyol such as a polyester polyol or a polyether polyol and a diisocyanate may be a low molecular weight compound having two or more active hydrogens such as a diol or a diamine, if necessary. Those obtained by elongating a chain in the presence of an elongating agent and stably dispersing or dissolving in water can be suitably used, and known ones can be widely used (for example, JP-B-42-24192, JP-B-42-24194, No. 42-5118, No. 49-986, No. 4
9-33104, JP-B-50-15027 and JP-B-53-29175). As a method for stably dispersing or dissolving the polyurethane resin in water, for example, the following method can be used.

(1) A method of imparting hydrophilicity by introducing an ionic group such as a hydroxyl group, amino group or carboxyl group into a side chain or a terminal of a polyurethane polymer, and dispersing or dissolving in water by self-emulsification.

(2) The reaction-completed polyurethane polymer or terminal isocyanate group is replaced with an oxime, alcohol,
A method in which a polyurethane polymer blocked with a blocking agent such as phenol, mercaptan, amine, and sodium bisulfite is forcibly dispersed in water using an emulsifier and mechanical shearing force. Further, a method of mixing a urethane polymer having a terminal isocyanate group with water / emulsifier / chain extender and simultaneously dispersing and increasing the molecular weight using mechanical shearing force.

(3) A method in which a water-soluble polyol such as polyethylene glycol is used as a polyol as a main raw material of polyurethane and dispersed or dissolved in water as a water-soluble polyurethane.

The above-mentioned dispersion or dissolution method is not limited to a single method, and a mixture obtained by each method can also be used for the polyurethane resin.

Examples of the diisocyanate which can be used for synthesizing the polyurethane resin include aromatic, alicyclic and aliphatic diisocyanates, and specifically, hexamethylene diisocyanate, tetramethylene diisocyanate, and 3,3'-dimethoxy-diisocyanate. 4,4′-biphenylene diisocyanate, p-xylylene diisocyanate,
m-xylylene diisocyanate, 1,3- (diisocyanatomethyl) cyclohexanone, 1,4- (diisocyanatomethyl) cyclohexanone, 4,4'-diisocyanatocyclohexanone, 4,4'-methylenebis (cyclohexyl isocyanate) , Isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-
Tolylene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, 2,4-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-biphenylene diisocyanate, and the like. . Of these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate are particularly preferred.

Commercially available polyurethane resins include Hydran HW-330, HW-340 and HW-340.
-350 (all manufactured by Dainippon Ink and Chemicals, Incorporated),
Superflex 100, 150, F-3438
D (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

As the polyvinyl alcohol resin,
It is preferably polyvinyl alcohol having a saponification degree of 87% or more, and particularly preferably so-called completely saponified polyvinyl alcohol having a saponification degree of 98% or more, and having a number average molecular weight of 3,000 to 100,000.
Is preferably within the range.

As the resin having a polyoxyalkylene chain, those having a polyoxyethylene chain or a polyoxypropylene chain can be suitably used. For example, polyethylene glycol, polypropylene glycol, the above polyoxyethylene chain and the above polyoxypropylene chain can be used. Blocked polyoxyalkylene glycol in which a chain is bonded in a block shape can be exemplified.

Examples of the olefin-carboxylic acid resin include a copolymer of an olefin such as ethylene and propylene and a polymerizable unsaturated carboxylic acid, and a polymerizable unsaturated compound added to a dispersion of the copolymer to emulsify. At least one kind of water-dispersible or water-soluble resin selected from two kinds of resins which are polymerized and crosslinked in the particles can be used.

The above copolymer comprises olefin and (meth)
It is a copolymer with one or more of unsaturated carboxylic acids such as acrylic acid and maleic acid. In the copolymer, the content of the unsaturated carboxylic acid is 3 to 60% by weight,
The content is preferably in the range of 5 to 40% by weight, and the copolymer can be dispersed in water by neutralizing the acid group in the copolymer with a basic substance.

The above resin is added to an aqueous dispersion of a copolymer,
It is a crosslinked resin formed by adding a polymerizable unsaturated compound, performing emulsion polymerization, and further performing intra-particle crosslinking. Examples of the polymerizable unsaturated compound include the vinyl monomers listed in the description of the water-dispersible or water-soluble acrylic resin.
The species or two or more species can be appropriately selected and used.

The compounding ratio of the aqueous organic polymer compound (C) is 10 to 2,000 parts by weight, particularly 100 to 1,000 parts by weight, per 100 parts by weight of the solid content of the aqueous liquid (A) containing titanium.
The amount within the range of 0 parts by weight is preferable from the viewpoints of stability of the liquid, anticorrosion property and the like.

Since the undercoating agent becomes a stable liquid in a neutral or acidic region, the pH is preferably in the range of 1 to 7, particularly 1 to 5.

The undercoating agent may include, for example,
In addition to the above-mentioned components, it contains a thickener, a surfactant, an antibacterial agent, a rust preventive (tannic acid, phytic acid, benzotriazole, etc.), a pigment such as a coloring pigment, an extender pigment, and a rust preventive pigment. be able to.

The undercoating agent may be used, if necessary, after being diluted with a hydrophilic solvent such as methanol, ethanol, isopropyl alcohol, ethylene glycol or propylene glycol.

Next, the coated steel sheet of the present invention will be described in detail.

Coated steel sheet The base metal material used for the coated steel sheet of the present invention includes:
There is no particular limitation, for example, a cold-rolled steel sheet, a hot-dip galvanized steel sheet, an electro-galvanized steel sheet, an iron-zinc alloy-coated steel sheet, a nickel-zinc alloy-coated steel sheet, an aluminum-zinc alloy-coated steel sheet (for example, “galvalume”). ,
Alloy-plated steel sheet sold under the trade name "Galphan"), aluminum-plated steel sheet, aluminum sheet, and the like. In general, an untreated material is suitable as a base metal material, but there is no particular problem even if the material is subjected to a chemical conversion treatment such as a chromate treatment, a zinc phosphate treatment, or a composite oxide film treatment.

The surface treating agent is applied to the surface of the underlying metal material and dried to form a surface treated film.

The undercoating agent is applied on a base metal material (which may be assembled) by a known coating method, for example, dip coating, shower coating, spray coating, roll coating, electrodeposition coating. It can be painted by such as. The drying condition of the undercoating agent is generally from about 2 seconds to about 30 under conditions where the maximum temperature at which the material reaches is about 60 to 250 ° C.
It is preferred to dry for minutes.

The dry film thickness of the undercoat agent is usually preferably in the range of 0.001 to 10 μm, particularly preferably in the range of 0.1 to 3 μm. When it is less than 0.001 μm, corrosion resistance,
The performance such as water resistance is inferior. On the other hand, if it exceeds 10 μm, it is not preferable because the surface treatment film is cracked or the workability is deteriorated.

An overcoat is coated on the surface-treated film with or without an undercoat. There is no particular limitation on the types of the undercoat and the overcoat, and they may be appropriately selected according to the purpose. For example, a coating composition is, from its form, a solvent-based coating, a water-based coating, a powder-based coating, and the like.
From the curing method to baking-curable paints, light-curable paints, air-drying paints, etc., and from the appearance of the coating film obtained by applying and drying the paint composition, to coloring paints, metallic paints, clear paints, etc. Classification is possible, but any can be used.

The top coat may be of one coat and one bake type, but may be of two coats and one bake, two coats of two bake,
A known method such as one-coat baking can be used, and a top coat may be formed on the undercoat through an intermediate coat.

Further, in addition to the usual top coating for cosmetics, an organic coating agent having functions such as lubricity and fingerprint resistance can be applied as a top coating.

[0094] The use of the coated steel sheet is, for example, used for building materials, home appliances, automobiles, cans and the like in which the conventional coated steel sheet is used.
It can be used without any particular limitation, and the coating of the undercoating paint and the topcoating paint may be appropriately selected depending on its use, the shape of the object to be coated, and the like. For example, spraying, brushing, electrodeposition, etc. are suitable for coating on molded products, and roll coating, curtain flow coating, etc., for coating on plate-like products such as pre-coated steel plates. It is preferably used.

[0095]

According to the present invention having the above-described structure, the following effects are considered to be obtained.

In the present invention, the undercoating agent having the above-mentioned composition is applied to a metal substrate such as a steel plate and heated to form an undercoating film. Certain phosphoric acid compounds, metal hydrofluoric acid, metal hydrofluoride, etc. act as metal etchants, while the aqueous liquid (A) containing titanium and the aqueous organic polymer compound (C) It is presumed that a film having excellent adhesion to the material and having low oxygen permeability and water vapor permeability is formed, and a coated steel sheet having extremely high corrosion resistance and durability can be obtained.

[0097]

The present invention will be described more specifically below with reference to examples and comparative examples. Hereinafter, “parts” and “%” mean “parts by weight” and “% by weight”, respectively. The present invention is not limited to the following examples.

Production Example 1 of Titanium-Based Aqueous Solution Ammonia water (1: 9) was added dropwise to a solution prepared by diluting 5 cc of a 60% titanium tetrachloride solution with 500 cc of distilled water to precipitate titanium hydroxide. After washing with distilled water, hydrogen peroxide water 30
% Solution was added and stirred to obtain a titanium-based aqueous liquid (A1) containing titanium and containing a translucent yellowish solid having a solid content of 2%.

Production Example 2 A mixture of 10 parts of tetra-iso-propoxytitanium and 10 parts of iso-propanol was stirred at 20 ° C. for 1 hour in a mixture of 10 parts of 30% hydrogen peroxide and 100 parts of deionized water. It was dropped. Thereafter, the mixture was aged at 25 ° C. for 2 hours, and was a yellowish, transparent, slightly viscous titanium-based aqueous liquid having a solid content of 2% (A
2) was obtained.

Production Example 3 Titanium-based aqueous liquid (A3) having a solid content of 2% under the same production conditions using tetra-n-butoxytitanium instead of tetra-iso-propoxytitanium in the production example of titanium-based aqueous liquid (A2) ) Got.

Production Example 4 Titanium-isopropoxytitanium trimer was used in place of tetraiso-propoxytitanium trimer in the production example of titanium-based aqueous liquid (A2). An aqueous liquid (A4) was obtained.

Production Example 5 In the production example of the titanium-based aqueous liquid (A2), hydrogen peroxide was added dropwise at 50 ° C. over 1 hour using a three-fold amount of aqueous hydrogen peroxide, and further added at 60 ° C.
For 3 hours to obtain a titanium-based aqueous liquid (A5) having a solid content of 2%.

Production Example 6 A titanium-based aqueous solution (A3) was heated at 95 ° C. for 6 hours.
White-yellow translucent titanium-based aqueous liquid having a solid content of 2% (A6)
I got

Production Example 7 A mixture of 10 parts of tetra-iso-propoxytitanium and 10 parts of iso-propanol was mixed with TKS-203 (Taika).
1 part in a mixture of 5 parts (solid content), 10 parts of 30% hydrogen peroxide solution and 100 parts of deionized water.
The mixture was added dropwise with stirring at 0 ° C. for 1 hour. Then 10
Aged at 24 ° C. for 24 hours, yellow transparent, slightly viscous solid 2
% Titanium-based aqueous liquid (A7).

Production Example 8 of Acrylic Resin 180 parts of isopropyl alcohol was placed in a 1 L four-necked flask equipped with a thermometer, a stirrer, a cooler, and a dropping funnel. C. and adjusted to a monomer mixture consisting of 140 parts of ethyl acrylate, 68 parts of methyl methacrylate, 15 parts of styrene, 15 parts of Nn-butoxymethylacrylamide, 38 parts of 2-hydroxyethyl acrylate and 24 parts of acrylic acid. Dropwise over about 2 hours with a catalyst consisting of 6 parts of 2,2'-azobis (2,4-dimethylvaleronitrile). When the reaction was continued at the same temperature for 5 hours after the completion of the dropwise addition, the polymerization rate was almost 100%, the solid content was about 63%, and the acid value was about 67.
A colorless and transparent resin solution is obtained. This resin solution 500
To this part, 108 parts of dimethylaminoethanol was mixed, and after adding water, the mixture was sufficiently stirred to obtain an aqueous acrylic resin dispersion (C1) having a solid content of 30%.

Production Example 9 of Amine-Modified Epoxy Resin A reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a liquid dropping apparatus was charged with Epicoat 1009 resin (epoxy resin manufactured by Shell Chemical Co .; molecular weight 3,750). 880g
(0.5 mol) and methyl isobutyl ketone / xylene =
After adding 1,000 g of a 1/1 (weight ratio) mixed solvent,
The mixture was stirred and heated to dissolve uniformly. Thereafter, the temperature was cooled to 70 ° C., and 70 g of di (n-propanol) amine collected in the liquid dropping device was dropped over 30 minutes. During this time, the reaction temperature was maintained at 70 ° C. After completion of the dropwise addition, the mixture was maintained at 120 ° C. for 2 hours to complete the reaction, whereby the solid content was 66%
An amine-modified epoxy resin was obtained. The obtained resin 1,0
25 parts of 88% formic acid was mixed with 00 g, and the mixture was sufficiently stirred after the addition of water to obtain an aqueous dispersion of an amine-modified epoxy resin (C2) having a solid content of 30%.

Preparation of Undercoating Agent S1 (for Example) 50 parts of 2% titanium-based aqueous liquid (A1), 5 parts of 20% zirconium hydrofluoric acid, 30% aqueous dispersion of acrylic resin (C
1) 10 parts and 35 parts of deionized water were blended to obtain a base treating agent S1.

Undercoating agents S2 to S11 (for Examples) and Undercoating agents H1 to H3 (for Comparative Examples) Except for the formulations shown in Table 1, each of the undercoating agents was prepared in the same manner as in the production example of the undercoating agent S1. Obtained.

[0109]

[Table 1]

Preparation of Test Coated Coating Method (1) Examples 1 to 11 and Comparative Examples 1 to 3 An electrogalvanized steel sheet having a thickness of 0.6 mm and a coating weight of 20 g / m ^{2 on} one side was degreased and washed, and then Then, the undercoating agent shown in Table 1 was applied so that the dry film thickness became 0.3 μm, and the PMT (maximum temperature of the steel sheet) was 100 in 15 seconds.
Each test coated plate was prepared by baking at a temperature of ℃. Then, Cosmer 2050 (manufactured by Kansai Paint Co., Ltd., trade name, acrylic / silica composite resin solution) is applied on each of the resulting treated plates so that the dry film thickness becomes 3 μm, and the PMT reaches 120 ° C. in 20 seconds. Each test plate was prepared by baking under the conditions.

Each of the test coated plates was tested for corrosion resistance and adhesion of the upper coating film. The test results are shown in Table 2 below. The test was performed according to the following test method.

Corrosion resistance: A salt water spray test specified in JIS Z2371 was performed on the test coated plate with the end surface and the back surface sealed, for up to 240 hours. The degree was evaluated according to the following criteria. a: no white rust is observed; b: white rust is less than 5% of the coating area; c: white rust is 5% or more and less than 10% of the coating area; d: white The degree of rust generation is 10% or more and less than 50% of the coating film area. E: The degree of white rust generation is 50% or more of the coating film area.

Adhesion of upper layer coating film: Amirac # 1000 white (manufactured by Kansai Paint Co., Ltd., thermosetting alkyd resin coating, white) was applied to the test coated plate so that the dry film thickness became 30 μm, and the coating was applied at 130 ° C. It was baked for 20 minutes to obtain a top-coated plate-1. Separately, Magiclon # 10 was added to the test coated plate.
00 white (manufactured by Kansai Paint Co., Ltd., thermosetting acrylic resin paint, white) is applied so as to have a dry film thickness of 30 μm, and baked at 150 ° C. for 20 minutes to give a topcoat plate-2.
I got With respect to the thus-obtained top-coated board-1 and top-coated board-2, eleven vertical and horizontal scratches reaching the substrate with a knife were cut into a grid on the coated surface to form 100 squares of 1 mm square. A cellophane pressure-sensitive adhesive tape was adhered to the grid, and the tape was instantaneously peeled off. The degree of peeling of the upper layer coating film was evaluated according to the following criteria. a: no peeling of the upper coating film is observed at all; b: 1-2 peeling of the upper coating film is observed; c: 3 to 10 peeling of the upper coating film are observed; d: peeling of the upper coating film 10 or more are observed.

[0114]

[Table 2]

Coating method (2) Examples 12 to 22 and Comparative examples 4 to 6 A hot-dip galvanized steel sheet having a thickness of 0.4 mm and a coating weight of 120 g / m ^{2 on} one side was degreased and washed, and then the above-mentioned undercoat treatment was performed. The composition was applied to a dry film thickness of 0.3 μm,
A treated plate was prepared under the condition that the PMT (maximum reached temperature of the steel plate) was 100 ° C. in seconds. Next, K
P color 8000 primer (manufactured by Kansai Paint Co., Ltd.
(Modified epoxy paint) so that the dry film thickness becomes 5 μm, and a coating film is formed under the condition that the PMT is 210 ° C. in 20 seconds.
580 white (manufactured by Kansai Paint Co., Ltd., polyester resin-based paint, white) is applied so that the dry film thickness becomes 15 μm, and baked under the condition that the PMT becomes 215 ° C. in 40 seconds, each test having an upper layer coating film A painted board was created. These test coated plates were tested for adhesion, corrosion resistance and moisture resistance of the upper layer coating film. The test results are shown in Table 3 below. Each test was performed according to the following test methods.

Adhesion of upper layer paint: 11 mm each of 11 vertical and horizontal scratches reaching the substrate with a knife on the surface of the coating film, 1 mm
100 corner squares were created. A cellophane pressure-sensitive adhesive tape was adhered to the grid, and the tape was instantaneously peeled off. The degree of peeling of the upper layer coating film was evaluated according to the following criteria. a: no peeling of the upper coating film is observed at all; b: 1-2 peeling of the upper coating film is observed; c: 3 to 10 peeling of the upper coating film are observed; d: peeling of the upper coating film 10 or more are observed.

Corrosion resistance: After sealing the end face and the back face of the test coating plate having the upper coating film cut into a size of 70 × 150 mm, a 4T folded portion (0 with the coating surface outside) was placed on the upper part of the test coating plate. (A part bent at 180 degrees with four spacers each having a thickness of .4 mm)) and a cross-cut portion is provided below the test coated plate according to JISZ2.
The salt spray test specified in 371 was performed for 1000 hours.
In the coated plate after the test, the degree of occurrence of white rust at the 4T bent portion, the blister width of the cross cut portion, and the blister occurrence degree of the general portion (the central portion without processing and cutting) were evaluated according to the following criteria. [Degree of blistering in general part] a: no blistering is observed, b: slight blistering is observed, c: considerable blistering is observed, d: remarkable blistering is observed. [Bulging width of cross cut part] a: One side bulge width from cross cut is less than 1 mm, b: One side bulge width from cross cut is 1 mm or more, 2
less than 5 mm, c: 5 when the one-sided blister width from the cross cut is 2 mm or more
mm: d: One-sided blister width from the cross cut is 5 mm or more. [Degree of generation of white rust at 4T bent portion] a: No white rust was generated, b: White rust was slightly generated, c: White rust was considerably generated, d: White rust was significantly generated.

[0118] Moisture resistance: The test coated plate having the upper and lower coating films sealed with the end face and the back surface was subjected to JIS K54.
A moisture resistance test was performed according to 9.2.2. The temperature inside the humidity tester box is 49 ° C and the relative humidity is 95-100.
%, The test time was 1000 hours. The degree of blistering of the coating film of the test coated plate after the test was evaluated according to the following criteria. a: no blistering is observed; b: slight blistering is observed; c: considerable blistering is observed; d: significant blistering is observed.

[0119]

[Table 3]

Coating Method (3) Examples 23 to 33 and Comparative Examples 7 to 9 An electrogalvanized steel sheet having a thickness of 0.6 mm and a coating weight of 20 g / m ^{2 on} one side was degreased and washed, and then placed on Table 1 above. Is applied so that the dry film thickness becomes 0.3 μm, and the PMT (maximum reached temperature of the steel sheet) is 100 in 15 seconds.
After baking at a temperature of 150 ° C., Magiclon # 1000 white (manufactured by Kansai Paint Co., Ltd., thermosetting acrylic resin paint, white) is applied to a dry film thickness of 30 μm and baked at 150 ° C. for 20 minutes. Each test coated plate was prepared.

Each of the test coated plates was tested for corrosion resistance and coating film adhesion. Table 4 below shows the test results.
Shown in The test was performed according to the following test method.

Adhesion of coating film: Eleven vertical and horizontal scratches reaching the substrate with a knife on the surface of the coating film were cut in a grid pattern to form 100 squares of 1 mm square. A cellophane pressure-sensitive adhesive tape was adhered to the grid, and the tape was instantaneously peeled off. The degree of peeling of the upper layer coating film was evaluated according to the following criteria. a: no peeling of the upper coating film is observed at all; b: 1-2 peeling of the upper coating film is observed; c: 3 to 10 peeling of the upper coating film are observed; d: peeling of the upper coating film 10 or more are observed.

Corrosion resistance: A salt water spray test specified in JIS Z2371 was performed for up to 240 hours on a test coated plate in which the end surface and the back surface of the test coated plate were sealed, and the degree of rust in the general coating portion and the degree of blister in the cross cut portion were measured. Was evaluated according to the following criteria, and the coating film peeling width (mm) after peeling off the cross cut portion with a tape was described. [Degree of white rust generation in general part] a: No white rust generated, b: White rust generation was less than 5% of coating area, c: White rust generation was 5% of coating area D: White rust generation is 10% or more and less than 50% of the coating film area. E: White rust generation degree is 50% or more of the coating film area. [Bulging width of cross cut part] a: One side bulge width from cross cut is less than 1 mm, b: One side bulge width from cross cut is 1 mm or more, 2
less than 5 mm, c: 5 when the one-sided blister width from the cross cut is 2 mm or more
mm: d: One-sided blister width from the cross cut is 5 mm or more.

[0124]

[Table 4]

Coating Method (4) Examples 34 to 44 and Comparative Examples 10 to 12 A 0.27-mm-thick # 5182 aluminum plate was degreased and washed, and then a base treating agent shown in Table 1 was dried thereon to obtain a dry film thickness. Paint to 0.3μm, PMT10 in 15 seconds
After baking at 0 ° C., Epicoat 1009 (manufactured by Japan Epoxy Resin Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent 3,500, number average molecular weight 3,7)
50) A clear coat consisting of 80 parts, 20 parts of Hitanol 4020 (a phenolic resin manufactured by Hitachi Chemical Co., Ltd.) and 0.4 part of phosphoric acid was applied with a roll coater so that the dry coating weight was 120 mg / cm ² , It was passed through a conveyor-conveying hot-air drying furnace to obtain a baking test coated plate. The baking conditions were such that the PMT was 240 ° C. and the passage time in the drying furnace was 20 seconds. Various tests were performed on the obtained test coated plate based on the following test methods. The test results are shown in Table 5 below.

Test Method Workability: Using a special goby-folding type Dupont impact tester, an aluminum plate having a thickness of 0.3 mm between the bent portions of a test coating plate whose lower part is folded in two so that the coating surface is on the outside. Is placed on the tester with one sheet sandwiched between them, and the contact surface is flat and 1kg thick
After dropping the iron weight from a height of 50 cm to give an impact to the bent portion, a current value (mA) of 2 mm width at the bent end portion when a voltage of 6.5 V is passed through the bent end portion for 6 seconds Was measured and evaluated according to the following criteria. ◎: Current value is less than 0.5 mA, ：: Current value is 0.5 mA or more and less than 1.0 mA, Δ: Current value is 1.0 mA or more and less than 5.0 mA, ×: Current value is 5.0 mA or more.

Processed part corrosion resistance: An aqueous solution obtained by dissolving 2 parts of malic acid, 2 parts of citric acid and 2 parts of sodium chloride in 100 parts of deionized water was prepared by using a lid press machine to form a test coated plate. After being stored in a room at 50 ° C. for 5 days with the coating surface of the test coated plate covered with the lid immersed in the contents, the can is cut open and the state of the can lid is observed. The evaluation was performed according to the following criteria. ◎: No abnormality was found in the can lid, ○: No rust was found in the can lid, but very slight change was observed, △: A little rust was observed in the can lid, ×: Significant rust was found in the can lid Is recognized.

Residual film resistance (feathering resistance): A lid was formed on a test coated plate in the same manner as in the case of evaluating the corrosion resistance of the processed portion, and the can lid was immersed in boiling water at 100 ° C. for 10 minutes. With the film surface facing down, the opening of the lid was opened so as to be lifted upward, and the peeling width of the coating film from the opening end was evaluated according to the following criteria. ◎: The maximum peel width of the coating film is less than 0.2 mm, ○: The maximum peel width of the coating film is 0.2 mm or more and less than 0.5 mm, and Δ: The maximum peel width of the coating film is 0.5 mm or more and 1.0 mm. Less than, ×: The maximum peel width of the coating film is 1.0 mm or more.

Retort whitening resistance: The test coated plate was immersed in water and treated in an autoclave at 125 ° C. for 30 minutes to evaluate the whitening state of the coating film according to the following criteria. ：: no whitening was observed at all; ○: very slight whitening was observed; Δ: slight whitening was observed; ×: significant whitening was observed.

Hygiene: The test coated plate and the activated carbon-treated tap water were placed in a heat-resistant glass bottle at a ratio of 1 cc of the activated carbon-treated tap water to 1 cm 2 of the coated surface of the test coated plate, and the lid was closed. The solution was treated in an autoclave at 125 ° C. for 30 minutes, and the liquid content after the treatment was evaluated for hygiene based on the consumption (ppm) of potassium permanganate according to the test method described in the Food Sanitation Law. ：: consumption amount is less than 1 ppm, ：: consumption amount is 1 ppm or more and less than 3 ppm, Δ: consumption amount is 3 ppm or more and less than 10 ppm, and X: consumption amount is 10 ppm or more.

Adhesion: Two test coated plates (150 × 5 m
m) sandwiching a nylon film with the coated surface of the m) as an adherend, and heating this at 200 ° C for 60 seconds,
For 30 seconds to fuse the nylon to both coating films to obtain a test piece. Next, the T-peel strength of the test piece was measured using a tensile tester (Shimadzu Autograph AGS-500A) at a tensile speed of 200 mm / min and a temperature of 20 ° C. The average value of five measurements was evaluated according to the following criteria. ◎: 3 kg / 5 mm or more, ：: 2 kg / 5 mm or more and less than 3 kg / 5 mm, Δ: 1 kg / 5 mm or more and less than 2 kg / 5 mm, ×: less than 1 kg / 5 mm.

[0132]

[Table 5]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 5/08 C09D 5/08 185/00 185/00 201/00 201/00 C23C 22/36 C23C 22 / 36 28/00 28/00 C (72) Inventor Osamu Isozaki 4-171-1, Higashiyawata, Hiratsuka-shi, Kanagawa F Kansai Paint Co., Ltd. F-term (reference) 4D075 AE03 AE27 CA04 CA09 CA13 CA33 CA38 DA06 DB02 DB05 DB07 DC01 DC10 DC11 DC18 DC42 EA06 EB07 EB13 EB19 EB20 EB22 EB32 EB33 EB38 EB39 EB51 EB56 EC01 EC08 EC15 EC54 4F100 AA04B AA05B AA21B AB01A AH08B AK01B AK01C AK01D AK03B AK21B AK25B AK33B AK51B AK53B AL03B BA04 BA07 BA10A BA10D CC00C CC00D GB07 GB32 GB48 JB02 JB07 JB09B JC00 JD03 JD04 JJ03 JK06 JL01 4J038 BA042 BA092 CB002 CE022 CG002 DA032 DB002 DF012 DG002 DH002 DM021 GA03 GA06 GA09 GA13 GA14 HA156 HA216 HA406 MA08 MA10 MA12 NA03 PA14 PB06 PC02 4K026 AA02 AA11 AA22 BA01 BA03 BA08 BB02 BB08 CA13 CA18 CA26 CA28 CA33 CA34 CA35 CA36 CA39 DA02 4K044 AA02 AB02 BA11 BA12 BB03 BB04 BC02 CA11 CA15 CA18 CA53

Claims (14)

[Claims] 1. A method according to claim 1, wherein (A) at least one titanium compound selected from the group consisting of a hydrolyzable titanium compound, a hydrolyzable titanium compound low condensate, titanium hydroxide and a titanium hydroxide low condensate. Aqueous liquid containing titanium obtained by reacting with aqueous hydrogen peroxide, (B) at least one compound selected from phosphoric acid compounds, metal hydrofluoric acid and metal hydrofluoride, and (C) A film is formed by an undercoating agent characterized by containing a stable aqueous organic polymer compound at a pH of 7 or less, and an overcoat film is formed on the undercoat film with or without an undercoat film. Painted steel sheet with excellent corrosion resistance. 2. The aqueous liquid (A) contains a titanium obtained by reacting a hydrolyzable titanium compound and / or a low-condensate of a hydrolyzable titanium compound with a hydrogen peroxide solution in the presence of a titanium oxide sol. The coated steel sheet according to claim 1, which is an aqueous liquid (A-1). 3. The coated steel sheet according to claim 1, wherein the aqueous liquid (A) is produced by adding a titanium compound to a hydrogen peroxide solution. 4. The coated steel sheet according to claim 1, wherein the hydrolyzable titanium compound is a titanium monomer containing a group that is hydrolyzed to become a hydroxyl group. 5. The method according to claim 1, wherein the low-condensation product of the hydrolyzable titanium compound is a low-condensation product of a titanium monomer containing a group that is hydrolyzed to become a hydroxyl group. Painted steel sheet as described. 6. The hydrolyzable titanium compound represented by the general formula Ti
(OR) _{4 wherein} R is the same or different and has 1 carbon atom
The coated steel sheet according to any one of claims 1 to 4, wherein the coated steel sheet represents an alkyl group of (1) to (5). 7. The coated steel sheet according to claim 1, wherein the low-condensate has a degree of condensation of 2 to 30. 8. The method according to claim 1, wherein the mixing ratio of the titanium compound to the hydrogen peroxide solution is 0.1 to 100 parts by weight of hydrogen peroxide per 10 parts by weight of the titanium compound.
4. The coated steel sheet according to any one of items 3 to 3. 9. Compound (B) is phosphoric acid, metaphosphoric acid,
Condensed phosphoric acid, condensed metaphosphoric acid, phosphate, metaphosphate, condensed phosphate, condensed metaphosphate, zirconium hydrofluoric acid, titanium hydrofluoric acid, hydrofluorosilicic acid, zirconium fluoride, titanium The coated steel sheet according to claim 1, wherein the coated steel sheet is at least one compound selected from a fluoride salt and a silicofluoride salt. 10. The compounding ratio of the compound (B) is 1 to 4 with respect to 100 parts by weight of the solid content of the aqueous liquid (A) containing titanium.
The coated steel sheet according to claim 1 or 9, wherein the amount is 00 parts by weight. 11. The aqueous organic polymer compound (C) is at least one of an epoxy resin, a phenol resin, an acrylic resin, a urethane resin, a polyvinyl alcohol resin, a polyalkylene glycol resin, and an olefin-carboxylic acid resin. The coated steel sheet according to claim 1, which is an aqueous organic polymer compound selected from one kind of resin. 12. The compounding ratio of the aqueous organic polymer compound (C) is 10 to 2,000 parts by weight based on 100 parts by weight of the solid content of the aqueous liquid (A) containing titanium. Item 12. The coated steel sheet according to item 1 or 11. 13. The coated steel sheet according to claim 1, wherein the undercoating agent is an aqueous liquid having a pH of 1 to 7. 14. A method comprising: (A) a hydrolyzable titanium compound, a hydrolyzable titanium compound low condensate,
Aqueous liquid containing titanium obtained by reacting at least one titanium compound selected from titanium hydroxide and titanium hydroxide low-condensate with aqueous hydrogen peroxide, (B) a phosphoric acid compound, metal hydrofluoric acid And at least one compound selected from metal hydrofluoride and (C) an aqueous organic polymer compound having a pH of 7 or less and a base treating agent having a dry film thickness of 0.001 to 0.001. A method for producing a coated steel sheet having excellent corrosion resistance, comprising forming an overcoat film with or without an undercoat film on the undercoat film after coating and drying so as to have a thickness of 10 μm.