JP2001271185A - Metal surface treating solution and surface treated metal with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treating solution excellent in a rust preventing capability for metallic materials and also excellent in adhesion with resins. SOLUTION: This aqueous surface treating solution for metallic materials contains one or more species selected from silicic acid and organosilicic compounds expressed by the following general formula (1) or (2) and amine, and is alkaline: R1Si(OR2)nR33-n (1) [wherein, R is a hydrocarbon substituted by one or more species selected from an epoxy group, a vinyl group, a methacrylic group, an amino group, a mercapto group, an imidazole group, halogen, a hydroxyl group, a styryl group and an acryl group, and may contain an ether bond or an ester bond; R2 and R3 are 1 to 5C alkyl groups and may contain an ether bond; and (n) denotes the integer of 1 to 3], and Si(OR8)4 (2) (wherein, R8 denotes a 1 to 5C alkyl group).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous surface treating agent for metal materials having excellent corrosion resistance and adhesion, and also having excellent adhesion to a resin.

[0002]

2. Description of the Related Art Although there are various requirements for various metals, rust prevention and adhesion (adhesion) with paints and resins are mainly required.

[0003] Steel products are used in various places such as buildings, automobiles, ships, cans and the like, but there is a strong demand for rust prevention. Conventionally, various rust preventive agents such as a water-soluble rust preventive, a volatile rust preventive, and an oil-based rust preventive have been used as rust preventives for iron products. Generally, a water-soluble rust inhibitor is intended for temporary short-time rust prevention and is not used for long-term rust prevention. Further, the vaporizable rust preventive exerts its original rust preventive power in a sealed state. Oil-based rust preventives have relatively strong rust-proofing properties and withstand long-term rust-proofing. Liquid rust-proof oil, tacky rust-preventive grease, rust-preventive additives, film-forming agents, etc. There are dissolved ones. However, rust-preventive oils and rust-preventive greases become sticky after surface treatment and cannot be used as undercoat materials such as coating films. Further, those obtained by dissolving a rust preventive additive, a film forming agent, and the like in a volatile organic solvent do not exhibit a sufficient rust preventive effect unless the film is thickened.

[0004] Galvanized steel sheets are commercially available to suppress the rust of iron. This is to prevent the rust of iron by the sacrificial anticorrosive action of zinc, which has a higher ionization tendency than iron. By subjecting the surface of the layer to a chemical conversion treatment such as a chromate treatment, white rust of the zinc layer is prevented, and the corrosion resistance is further enhanced. However, this chromate treatment
Although high rust resistance can be obtained even with a thin film, environmentally-friendly problems have demanded a rust-preventive film instead of this. At present, tannic acid has been proposed as a rust-preventive coating on galvanized steel sheets, but it is not possible to say that rust-preventing properties are sufficiently obtained compared to chromate treatment and that coating film adhesion is not sufficient. .

[0005] In addition to the above chromate treatment, copper products
Benzotriazole is commonly used as a rust inhibitor. This shows excellent rust prevention, but does not provide sufficient adhesion to a resin or the like. To improve the adhesiveness of resins, etc., generally, a syringe coupling agent treatment has been proposed,
At present, commercially available silane coupling agents do not provide sufficient rust prevention of copper.

[0006] Aluminum or aluminum alloys are attracting attention in various fields because of their light weight. However, since a coating of aluminum oxide is formed on the surface, even if the paint is directly applied to aluminum, the adhesion is not sufficient. Many methods have been proposed as a chemical conversion treatment method for a coating base, and many patents have been published today, but at present, the chromate method is the mainstream in the United States and Japan. However, similar to the above galvanized steel sheet, chromate treatment is not environmentally preferable, and non-chromate treatment is desired. Further, a method of treating the surface of the metal with an aqueous solution of an alkali metal salt of silicic acid for the purpose of imparting properties such as corrosion resistance and antistatic properties has been proposed,
The desired properties cannot be obtained unless the treatment temperature is high or boiling water immersion or acid immersion is performed as a post-treatment to remove the alkali metal.

The present inventors have already proposed a coating composition comprising silicic acid and a specific alkoxysilane to solve such a problem (JP-A-10-959).
No. 33). However, although this composition exhibits a sufficient rust-preventing effect in a solvent system, it has a rust-preventing effect in an aqueous system, but its effect is not sufficient. Further, the substrate treated with this coating agent has insufficient corrosion resistance after alkali degreasing.

[0008]

SUMMARY OF THE INVENTION The present invention can meet such a demand, that is, it strongly adsorbs to a metal material on a metal surface, has a rust preventive action even in a thin film, and has excellent adhesion to a resin. It is an object of the present invention to provide a coated coating composition and a metal material whose surface is treated.

[0009]

Means for Solving the Problems The present inventors have made intensive studies on further improvement of the coating composition, and as a result, have found that the addition of ammonia, alkylamine and the like can greatly improve rust prevention. . In addition, they have found that by further adding a water-soluble resin, the corrosion resistance after alkali degreasing can be improved, and the present invention has been accomplished.

That is, the present invention is characterized by containing (1) silicic acid, at least one selected from organosilicon compounds represented by the following general formula (1) or (2), and an amine, and being alkaline. R ¹ Si (OR ² ) _n R ³³ _3-n (1) wherein R ¹ is an epoxy group, a vinyl group, a methacryl group,
Amino group, mercapto group, imidazole group, halogen,
It is a hydrocarbon substituted with one or more of a hydroxyl group, a styryl group, and an acrylic group, and may contain an ether bond or an ester bond. R ² and R ³ are alkyl groups having 1 to 5 carbon atoms and may contain an ether bond. n is 1
Represents an integer of 3 to 3] Si (OR ⁸ ) ₄ (2) (wherein R ⁸ represents an alkyl group having 1 to 5 carbon atoms) (2) The above-mentioned (1), wherein a water-soluble resin is further added. The present invention relates to an aqueous surface treatment liquid for metal materials, and (3) a metal material coated with the aqueous surface treatment liquid for metal materials according to (1) or (2).

In the present invention, the mechanism of rust prevention is not clear, but by making the surface treatment solution alkaline, the condensation of siloxane in the surface treatment solution is promoted and the film forming property during coating is improved. it is conceivable that. When a water-soluble resin is further added, the water-soluble resin and silicic acid or an organosilicon compound react or hydrogen bond to form a hybrid treatment film on the metal surface. Excellent alkalinity.

Hereinafter, the present invention will be described in more detail. As the silicic acid used in the coating composition of the present invention,
Silicic acid obtained by removing a metal from a metal salt of silicic acid is particularly preferred. As a method of removing a metal from a metal salt of silicic acid,
(1) After adding a metal salt of silicic acid to an aqueous solution containing an acid that is more acidic than silanol, a water-soluble organic solvent such as alcohol, ketone, or ether is added, and the mixture is stirred for a certain period of time.
It is preferable to separate out the organic layer containing silicic acid by salting out, and (2) to exchange the metal for hydrogen by adding an ion exchange resin to an aqueous solution of a metal salt of silicic acid.

If the acid used in the above method (1) is a stronger acid than silanol, the effect of the present invention can be sufficiently exhibited, but the possibility that inorganic acids such as hydrochloric acid and sulfuric acid may be mixed into the organic layer. Is preferred because of the small amount. For salting out, inorganic salts may be added to the solution. Inorganic salts used for salting out include salt, potassium chloride, potassium carbonate, calcium chloride, ammonium chloride, sodium sulfate, sodium acetate, ammonium sulfate, magnesium sulfate and the like. Among them, salt is preferable because it is inexpensive and there is not much difference in solubility depending on the temperature. As the water-soluble organic solvent, any solvent may be used as long as it is a solvent that separates from the aqueous layer after salting out, but it is necessary that the solvent does not have a high boiling point and that it does not become a condensation catalyst for silicic acid. Preferred are alcohols such as -propanol and t-butyl alcohol, ketones such as acetone, and ethers such as tetrahydrofuran.

The ion exchange resin used in the above method (2) may be any as long as it can exchange the metal part of the metal salt of silicic acid with hydrogen, and a cation exchange resin is suitable. [Manufactured by Organo Corporation].

The metal salt of silicic acid used may be natural or synthetic, and includes, for example, calcium silicate, sodium silicate, potassium silicate and the like.

If the concentration of the silicic acid solution obtained in the above (1) or (2) is 0.01 g / l to 100 g / l, the effect of the present invention is exhibited. If it is less than 0.01 g / l, a sufficient film-forming property cannot be obtained when a metal is subjected to a surface treatment, and rust prevention is not sufficient. On the other hand, if it exceeds 100 g / l, silicic acid tends to gel, which is not preferable in terms of solution stability. The silicic acid concentration is particularly preferably from 0.1 g / l to 40 g / l.

When a specific alkoxysilane is added to the above-mentioned silicic acid solution, water repellency is improved and rust prevention is further improved. Further, since the wettability with an organic substance is also improved, the adhesion with a resin such as a paint is also improved.

As the kind of the alkoxysilane which is an organosilicon compound used in the present invention, a compound represented by the following general formula (1) or (2) can sufficiently exert the effects of the present invention. The compound of the general formula (1) contributes to the improvement of the rust prevention and the adhesiveness of the resin, and the tetraalkoxysilane of the general formula (2) mainly contributes to the improvement of the rust prevention.

R ¹ Si (OR ² ) _n R ³ _3-n (1) wherein R ¹ is an epoxy group, a vinyl group, a methacryl group,
Amino group, mercapto group, imidazole group, halogen,
It is a hydrocarbon substituted with one or more of a hydroxyl group, a styryl group, and an acrylic group, and may contain an ether bond or an ester bond. R ² and R ³ are alkyl groups having 1 to 5 carbon atoms and may contain an ether bond. n is 1
Shows an integer of ~ 3]

Si (OR ⁸ ) ₄ (2) (wherein R ⁸ represents an alkyl group having 1 to 5 carbon atoms)

The hydrocarbon represented by R ¹ in the general formula (1) is ^one of an epoxy group, a vinyl group, a methacryl group, an amino group, a mercapto group, an imidazole group, a halogen, a hydroxyl group, a styryl group and an acrylic group. An alkyl group having 1 to 20 carbon atoms, a cycloalkyl group,
Alternatively, a phenyl group is preferred.

As the silane coupling agent which is an organosilicon compound represented by the above general formula (1), n is 2 or 3 because the more alkoxy groups in one molecule improve the reactivity with silicic acid. Is preferred. Commercially available or synthesized silane coupling agents may be used, and amino-, epoxy-, acryl-, chloroalkyl-, vinyl-, cationic-styryl-, mercapto-, and imidazole-based silane coupling agents are preferred. As the amino-based silane coupling agent, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and the like are preferable. As the epoxy silane coupling agent, 3
-Glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, β- (3,4 epoxycyclohexyl) ethyl Trimethoxysilane and the like are preferred. As the acrylic silane coupling agent, 3-
Methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane and the like are preferable. As the chloroalkyl-based silane coupling agent, 3-chloropropyltrimethoxysilane and the like are preferable. As the vinyl silane coupling agent, vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tris (β methoxy ethoxy) silane and the like are preferable. As the cationic styryl silane coupling agent, N-β- (N-
(Vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane.hydrochloride and the like are preferable. As the mercapto-based silane coupling agent, 3-mercaptopropyltrimethoxysilane and the like are preferable. As the imidazole silane coupling agent, the following general formulas (4) and (5)
-1), (5-2) and (5-3) are preferred. The compound of general formula (4) is synthesized by a dehydrochlorination reaction of chloroalkylsilane and imidazole, and the compound of general formula (5) is synthesized by reaction of imidazole with epoxy silane coupling agent.

[0023]

Embedded image

[0024] ^{(R 1, R 2, R} 3 is hydrogen, an alkyl group, a vinyl group, .R ⁵ is .R ⁴ is a phenyl group or a benzyl group which is an alkyl group or an alkoxyalkyl group having 1 to 5 carbon atoms An alkyl group having 1 to 5 carbon atoms, and m is 1 to 5.
10, n is an integer of 1 to 3. However, R ² and R ³ may combine to form a benzene ring, in which case they are benzimidazole groups. )

[0025]

Embedded image (R ¹ , R ² , R ³ , R ⁴ , R ⁵ , m, and n have the same meaning as in the general formula (4))

Examples of the tetraalkoxysilane is an organic silicon compound represented by the general formula (2), since the person number of carbon atoms in the alkoxy group is small is improved hydrolyzable silane, R ⁸ is a methyl group, an ethyl group Are preferred. Tetraalkoxysilane acts as a binder for improving film forming properties. That is, when tetraalkoxysilane is added to the silicic acid solution, it acts as a binder between the silicic acids to improve rust prevention.

Further, by adding tetraalkoxysilane to the silicic acid solution to which the above-mentioned “compound of the general formula (1)” has been added, it can be effectively used as a binder between the silicic acid and the “compound of the general formula (1)”. It acts to improve rust prevention and adhesion to resin.

The effects of the present invention can be sufficiently exhibited by adding the compound of the above general formula (1) or (2) to the silicic acid solution in an amount of 1 g / l or more and 200 g / l or less. These compounds may be used alone or in combination.

When the above-mentioned coating solution is used as a metal surface treating agent, the target metal is not particularly limited.
Copper, steel, aluminum, zinc and their alloys, and those coated with zinc, etc., or used as a coating agent for those subjected to a chemical conversion treatment such as chromate treatment, phosphate treatment, etc. It is suitable. In particular, a galvanized steel sheet and a sheet subjected to a chromate treatment are particularly preferable. The thickness varies depending on the type and use of the metal, but is preferably several molecular layers to several hundred μm.

The above-mentioned coating solution may be applied to the metal as it is, but it is convenient and preferable to dilute it with water and apply it by spin coating, brushing, dipping, showering or the like.

After the surface treatment of the coating solution, the effect of the present invention can be sufficiently exerted even if the coating solution is air-dried. However, it is preferable to heat and dry the coating solution in order to strengthen the bonding of the siloxane film. Heat drying with hot air from a dryer is sufficient, but drying at 80 to 240 ° C. for 1 to 10 minutes is more preferable. In addition, you may process by mixing additives, such as a rust inhibitor and a solution stabilizer, in a coating liquid.

In the present invention, ammonia or an alkylamine is used as the amine to be added to the silicic acid and the organosilicon compound. Examples of the alkylamine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, and isopropylamine. The amine is added to make the aqueous surface treatment solution alkaline.

The water-soluble resin used in the present invention is not particularly limited. Examples thereof include polyvinyl alcohol, saponified polyvinyl acetate, melamine resin, alkyd resin, polyester, polyethylene glycol, epoxy resin, acrylic resin, and the like. Examples include urethane resin, acrylic silicone, and cellulose. The addition amount of these water-soluble resins is 1 g / l in the above surface treatment agent.
If it is ８００800 g / l, the effect of the present invention is sufficiently exhibited.

[0034]

EXAMPLE 1 Preparation of aqueous solution of silicic acid 16 g of sodium disilicate (manufactured by Kanto Kagaku) was dissolved in pure water to make a total volume of 400 mL. 268 g of ion exchange resin (Amberlyst 31) was added to this solution, and the mixture was stirred for 1 hour. After stirring for 1 hour, the ion exchange resin was removed by filtration to prepare an aqueous solution of silicic acid (solid content: 2.4 to 2.6).
%, PH 2.5).

Preparation of an imidazole silane aqueous solution After adding 2 g of acetic acid to 80 g of pure water, a mixed solution of 10 g of an imidazole silane mixture of the following formula and 1 g of methanol synthesized from imidazole and an epoxy-based silane coupling agent by a known method was used. It was slowly added and dissolved. After the pH was adjusted to 5 with acetic acid, the total amount was adjusted to 100 g, and 10% by mass.
An imidazole silane solution was prepared.

[0036]

Embedded image

Of imidazole silane / silicic acid acidic aqueous solution
Preparation (Solution 1, Comparative Example) The aqueous solution of silicic acid and the aqueous solution of imidazole silane were mixed at a solid content ratio of 5/4 to prepare an aqueous solution of imidazole silane / acid of silicic acid. PH at that time is 4.8 ~
It was 5.4.

Preparation of TEOS Acidic Aqueous Solution After 160 g of pure water was adjusted to pH 3 with 1N hydrochloric acid, 40 g of tetraethoxysilane (TEOS) was added, and 55 ° C.
For 1 hour to prepare a 20% by mass aqueous TEOS solution.

Imidazole silane / silicic acid / TEOS acid
Preparation of Aqueous Aqueous Solution (Solution 2, Comparative Example) The above imidazole silane / silicic acid acidic aqueous solution (40 ml) and a 20% TEOS acidic aqueous solution (8 ml) were mixed to prepare an imidazole silane / silicic acid / TEOS aqueous solution.

Imidazole silane / silicic acid / TEOS
Preparation of Lucari Aqueous Solution (Solution 3) 1 g of 29% ammonia water was added to 20 g of the above imidazole silane / silicic acid / TEOS acidic aqueous solution to obtain an alkaline aqueous solution.

Surface treatment of galvanized steel sheet A zinc-coated steel sheet (gin coat, non-chromate product, manufactured by Nippon Steel, size: 6 cm × 8 cm × 0.6 mm) was degreased with hexane and an alkaline degreaser, and then prepared as described above. Solutions 1 to 3 were surface-treated by spin coating. After the surface treatment, heat treatment was performed at 80 ° C. for 5 minutes to prepare galvanized steel sheets having various surface treatments.
1.0g / m ^2).

Evaluation of Rust Prevention of Galvanized Steel Sheet The galvanized steel sheet subjected to the above surface treatment was put in a salt water sprayer, and the rust prevention was evaluated by spraying 5% saline at 35 ° C. As a result, in the galvanized steel sheet treated with the solution 1 and the solution 2, white rust was generated on the entire surface within 24 hours, whereas in the galvanized steel sheet treated with the solution 3, the generation of white rust was within 10% of the entire surface. Met.

Example 2 Imidazole silane / silicic acid / TEOS / water-soluble resin water
Solution A water-soluble resin was added to the above imidazole silane / silicic acid acidic aqueous solution or the imidazole silane / silicic acid / TEOS alkaline aqueous solution. The mass ratio is as follows.

Solution 4 (Comparative Example): The above imidazole silane / silicic acid acidic aqueous solution and a 30% water-soluble epoxy resin (EMO436, manufactured by Asahi Denka Kogyo KK) in a mass ratio of 1/1.
Mixed with

Solution 5: The above imidazole silane / silicic acid / TEOS alkaline aqueous solution and a 5% water-soluble epoxy resin (EMO434, manufactured by Asahi Denka Kogyo KK) in a mass ratio of 1 /
Mixed with 1

Solution 6: The above imidazole silane / silicic acid / TEOS alkaline aqueous solution and a 10% water-soluble alkyd resin (manufactured by Harima Chemicals, Haridip WS-62)
0) at a mass ratio of 1/2

Solution 7: The above imidazole silane / silicic acid / TEOS alkaline aqueous solution, 5% water-soluble epoxy resin (manufactured by Asahi Denka Kogyo Co., Ltd., EMO434), and 10% water-soluble alkyd resin (manufactured by Harima Chemicals, Inc.) HARIDIP WS-620) at a mass ratio of 1/2

Surface treatment of galvanized steel sheet After galvanized steel sheet was degreased with hexane and an alkaline degreasing agent, the solutions 4 to 7 prepared above were surface-treated by spin coating. After the surface treatment, a heat treatment was performed at 160 ° C. for 5 minutes to prepare various surface-treated galvanized steel sheets (surface treatment amount: 0.8 to 1.5 g / m ² ).

Evaluation of Rust Prevention of Galvanized Steel Sheet The galvanized steel sheet subjected to the surface treatment was placed in a salt sprayer and sprayed with 35% saline at 35 ° C. to evaluate the rust prevention. As a result, the galvanized steel sheet treated with the solution 4 partially generated white rust after 24 hours, whereas the galvanized steel sheet treated with the solutions 5 to 7 hardly generated white rust.

The galvanized steel sheet treated with the solution 7 was immersed in an alkaline degreasing solution for 2 minutes and sprayed with salt water. As a result, it was confirmed that the formation of white rust was slightly observed after 24 hours and the rust resistance was excellent.

Evaluation of Coating Adhesion on Galvanized Steel Sheet Melamine alkyd resin was applied to the galvanized steel sheet surface-treated with the above solution 7 at a thickness of 20 μm, heat-treated at 130 ° C. for 20 minutes, and the primary adhesion was evaluated by a grid test. After immersion in boiling water for 3 hours, a cross-cut test was performed to evaluate secondary adhesion. As a result, the galvanized steel sheet surface-treated with the solution 7 showed good adhesion without any peeling of the coating film in the primary and secondary adhesion tests.

Surface treatment of aluminum plate An aluminum plate (1050, 20) having a size of 55 × 55 × 1 mm
24) After alkali degreasing, the composition was applied to a thickness of 1 μm using Solution 7 using a spin coater.
Heat treatment was performed at 60 ° C. for 5 minutes to prepare a surface-treated aluminum plate.

Evaluation of Rust Prevention of Aluminum Sheet The above-treated aluminum sheet was placed in a salt sprayer,
Rust prevention was evaluated by spraying 5% saline at 35 ° C. As a result, rust hardly occurred even after 120 hours, and good rust prevention was obtained.

[0054]

As described above, the metal surface treating solution of the present invention is useful as a metal surface treating agent and has an effect of being excellent in rust prevention and adhesiveness to a resin.

Continued on the front page F term (reference) 4J038 BA021 CE021 CG031 CG141 CG142 DA161 DB001 DB171 DD001 DD121 DD231 DF021 DF022 DG001 DG002 DL021 DL051 DL071 DL081 DL091 DL111 GA02 GA03 GA06 GA07 GA09 GA12 GA13 HA156 HA446 JC31 JC32 JC35 J446 AA02 AA07 AA22 BA01 BA02 BA06 BB06 BB08 BB10 CA15 CA27 CA37 CA38 CA39 EB07 4K062 AA01 BA08 BB03 BB12 BB18 BB30 BC08 BC09 BC12 BC13 BC15 CA03 FA12 GA03

Claims (3)

[Claims] 1. Silicic acid, represented by the following general formula (1) or (2)
At least one selected from organosilicon compounds represented by
An aqueous surface treatment liquid for a metal material, comprising: an alkali and an amine. R ¹ Si (OR ² ) _n R ³ _3-n (1) wherein R ¹ is an epoxy group, a vinyl group, a methacryl group,
Amino group, mercapto group, imidazole group, halogen,
It is a hydrocarbon substituted with one or more of a hydroxyl group, a styryl group, and an acrylic group, and may contain an ether bond or an ester bond. R ² and R ³ are alkyl groups having 1 to 5 carbon atoms and may contain an ether bond. n is 1
Represents an integer of 3 to 3] Si (OR ⁸ ) ₄ (2) (wherein, R ⁸ represents an alkyl group having 1 to 5 carbon atoms) 2. The aqueous surface treating solution for a metal material according to claim 1, further comprising a water-soluble resin. 3. A metal material to which the aqueous surface treatment liquid for a metal material according to claim 1 is applied.