JP2000204485A - Non-chrome coating agent for metal surface - Google Patents

Abstract

(57) [Problem] To provide a metal surface treatment agent having high corrosion resistance and high adhesion that does not cause peeling of a coating film coated thereon even in a severe environment. SOLUTION: An aqueous solution or an aqueous dispersion containing a resin in an amount of 0.5 g / l to 200 g / l contains a nitrogen atom having a lone pair of electrons such as imidazoles, triazines, triazoles, guanines and guanidines. To a compound
A metal surface treatment agent containing 1 g / l to 20 g / l. 0.
An aqueous solution or an aqueous dispersion containing the resin in an amount of 5 g / l to 200 g / l contains 0.1 g / l to 20 g / l of a compound containing a nitrogen atom having a lone electron pair such as the above imidazoles.
And a metal surface treatment agent containing a zirconium compound in an amount of 0.1 g / l to 50 g / l as zirconium ions.
A method of surface-treating a metal with the above-mentioned metal surface treating agent. A metal material that has been surface-treated with the above metal surface treatment agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal surface treatment agent,
In particular, the present invention relates to a coating base treating agent for aluminum and alloyed aluminum.

[0002]

2. Description of the Related Art Conventionally, a chromium-based surface treatment agent such as a chromate treatment or a phosphoric acid chromate treatment has been applied to an aluminum coating base treatment agent, and is still widely used at present. However, according to the recent trends in environmental regulations,
Chromium's toxicity, especially carcinogenicity, may limit its use in the future. As a chromium-free treatment agent, an aqueous composition comprising a zirconium compound and a polymer as disclosed in JP-A-50-3932,
In particular, there is a method of surface treating aluminum, but this composition does not always provide sufficient corrosion resistance after painting. Further, as disclosed in JP-A-55-38997, a polymer selected from polyacrylic acid and its ester and H ₂ Zr
Although a coating agent for aluminum comprising a compound selected from F ₆ , H ₂ TiF ₆ and H ₂ SiF ₆ is disclosed, this composition does not provide sufficient post-paint corrosion resistance.
Furthermore, Japanese Patent Application Laid-Open No. 10-102264 discloses a surface treatment agent for aluminum containing a polymer and a component selected from an oxide of HTiF or Ti or Ti, but the corrosion resistance and adhesion after coating are not always sufficient. Improvement was needed. Japanese Patent Application Laid-Open No. 9-20984 discloses that a phosphate ion and a Ti compound or a fluorine compound have a pH of 1.0 to 4.5.
Although surface treatment agents for aluminum have been disclosed, this system is inconvenient to handle because it has a strongly acidic pH and further contains harmful fluorine ions, and furthermore, the corrosion resistance and the adhesion after painting are not always sufficient. Therefore, a surface treatment agent that further improves corrosion resistance and coating adhesion has been desired. Especially in the case of aluminum blinds, an acidic titanium-based treatment agent is generally used as a coating base treatment agent. However, when the painted aluminum blind is exposed to an environment such as a bathroom where high temperature, high humidity, and wet drying are repeated, the coating of the coating film may be damaged. There was a problem that peeling occurred.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal surface treatment agent having high corrosion resistance and high adhesion which does not cause peeling of a coating film coated thereon even in a severe environment. It is to be.

[0004]

According to the present invention, 0.5 g / l of the present invention is provided.
Imidazoles, triazines, triazoles, in aqueous solutions or aqueous dispersions containing resins in amounts of up to 200 g / l,
One or more compounds containing a nitrogen atom having a lone pair of electrons such as guanines and guanidines are added in an amount of 0.1 g / g.
The present invention relates to a metal surface treatment agent containing 1 to 20 g / l. Further, the present invention provides a method for preparing a nitrogen atom having a lone pair of electrons such as imidazoles, triazines, triazoles, guanines and guanidines in an aqueous solution or an aqueous dispersion containing a resin in an amount of 0.5 g / l to 200 g / l. One or more of the compounds contained is 0.1 g / l to 20 g / l and the zirconium compound is 0.1 g / l as zirconium ions.
The present invention relates to a metal surface treatment agent containing 〜50 g / l. The present invention also relates to a method for surface-treating a metal with the above-mentioned metal surface treating agent. Furthermore, the present invention relates to a metal material surface-treated with the above metal surface treatment agent.

[0005] By applying the surface treating agent of the present invention obtained as described above to a metal surface as a coating base treating agent, the metal is imparted with high corrosion resistance and, at the same time, has excellent compatibility with the coating film applied thereon. Adhesion can be imparted.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a compound containing a nitrogen atom having a lone pair of electrons, such as imidazoles, triazines, triazoles, guanines, guanidines, etc. Or a compound containing a nitrogen atom having a lone pair of electrons such as triazoles), or a zirconium compound. . The resin that can be used in the present invention may be any water-soluble or stable aqueous dispersion, such as a resin that can form an emulsion or a suspension to form a coating film, such as polyacrylic acid. And at least one resin selected from the group consisting of polyacrylic acid esters in which at least a part of polyacrylic acid is esterified, polyolefin-based resin, polyurethane-based resin, acrylic-based resin, polyester-based resin, and epoxy-based resin And aqueous dispersions of the above. Preferred resins are polyacrylic acid and esters of polyacrylic acid in which at least a part of polyacrylic acid is esterified.

In the metal surface treating agent of the present invention, the amount of the resin is 0.1.
5 g / l to 200 g / l, preferably 2 g / l to 50 g
/ L. If the content of the resin is less than 0.5 g / l, the film thickness when applied becomes thin, and sufficient corrosion resistance cannot be obtained. When the content of the resin exceeds 200 g / l, storage stability as a solution or an aqueous dispersion is lowered due to gelation or the like.

The imidazoles that can be used in the present invention are preferably soluble in water, and any of the following can be used: imidazole, 2-methylimidazole, 4-methylimidazole, 4-methyl-5- (Hydroxymethyl) methylimidazole, 2-amino-4,5-dicyanoimidazole, imidazole-4,5-dicarboxylic acid, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-hepta Decyl imidazole, 1-benzyl-2-methyl-imidazole, 2-phenyl-4-methyl-imidazole, 1-cyanoethyl-2-methyl-imidazole, 1-cyanoethyl-2-
Phenyl-imidazole, 1-cyanoethyl-2-ethyl-
4-methyl-imidazole, 1-aminoethyl-2-methyl-
Imidazole, 1- (cyanoethylaminoethyl) -2-
Methyl-imidazole, N- [2- (2-methyl-1-imidazolyl) ethyl] urea, 1-cyanoethyl-2-undecyl-
Imidazole, 1-cyanoethyl-2-methyl-imidazole trimellitate, 1-cyanoethyl-2-phenyl-imidazole trimellitate, 1-cyanoethyl-2-ethyl-
4-methyl-imidazole trimellitate, 1-cyanoethyl-2-undecyl-imidazole trimellitate, 2,
4-diamino-6- (2-methyl-imidazolyl) -ethyl-
1,3,5-triazine, 2,4-diamino-6- (2-undecyl-1-imidazolylethyl) -1,3,5-triazine,
2,4-diamino-6- (2-ethyl-4-methyl-1-imidazolylethyl) -1,3,5-triazine, 1-dodecyl-2
-Methyl-3-benzylimidazolium chloride, N,
N'-bis (2-methyl-1-imidazolylethyl) urea,
N, N '-(2-methyl-1-imidazolylethyl) adipamide, 2,4-dialkylimidazole-5-dithiocarboxylic acid, 1,3-dibenzyl-2-methylimidazolium chloride, 2-phenyl-4-methyl -5-hydroxymethylimidazole, 2-phenyl-4,5-bis (hydroxymethyl) imidazole, 1-cyanoethyl-2-phenyl-4,
5-bis (cyanoethoxymethyl) imidazole, 2-methylimidazole / isocyanuric acid adduct, 2-phenylimidazole / isocyanuric acid adduct, 2,4-diamino-6- (2-methyl-1-imidazolylethyl) -1 , 3,5
-Triazine / isocyanuric acid adduct, 2-alkyl-4-
Formyl imidazole, 2,4-dialkyl-5-formyl imidazole.

The triazines usable in the present invention are preferably soluble in water, and any of the following can be used: 1,2,3-triazine, 1,2,4-triazine, 3,5-triazine, 1,3,5-triazinetricarboxylic acid.

Any of the following triazoles can be used: 1,2,3-triazole, 1,2,
5-triazole, 1,2,4-triazole, 1,3,4-
Triazole.

As the guanines, any of the following can be used: guanine (2-amino-6-oxypurine), guanine deoxyriboside, guanine deoxyriboside phosphate, and guanine riboside.

Any of the following guanidines can be used: guanidine, guanidinoacetic acid, guanidinocarbonate ethyl ester, dl-2-guanidinopropionic acid, aminoguanidine, guanylthiourea, guanylurea, guanyltoluene. Compounds containing a nitrogen atom having a lone pair of electrons such as the above imidazoles can be used alone or as a mixture of two or more in the metal surface treatment agent of the present invention.

In the metal surface treating agent of the present invention, a compound containing a nitrogen atom having a lone electron pair, such as imidazoles, is 0.1 g / l to 20 g / l, preferably 1 g / l to 10 g / l.
g / l. If the compounding amount of a compound containing a nitrogen atom having a lone electron pair, such as imidazoles, is less than 0.1 g / l, the effect of improving corrosion resistance is lost and 20 g / l.
If the ratio exceeds, the effects of corrosion resistance and paint adhesion are saturated, which is uneconomical.

The zirconium compound is preferably soluble in water. Examples of the zirconium compound usable in the present invention include zirconyl ammonium carbonate, ammonium zircon fluoride, potassium zircon fluoride, sodium zircon fluoride and zircon hydrofluoric acid. The zirconium compound is 0.1 g / l to 50 g / l, preferably 2 g / l to zirconium ions in the metal surface treatment agent.
10 g / l is contained. 0.1 g of zirconium ion /
When the amount is less than 1 g, the corrosion resistance becomes insufficient, and when the amount exceeds 50 g / l, the solution or the dispersion gels and the storage stability decreases.

The mechanism for improving the corrosion resistance of metals by the surface treatment agent of the present invention is considered as follows. By applying the surface treating agent of the present invention to a metal, particularly aluminum or its alloy surface, it is considered that a layer of zirconium oxide or zirconium hydroxide is formed on the metal surface, and further a resin film is formed thereon. . It is considered that the zirconium layer and the resin film are not clearly separated from each other, but zirconium serves as a cross-linking agent for the resin and accelerates the curing of the resin film to improve the corrosion resistance. Here, when compounds such as imidazoles are present, it is considered that nitrogen atoms of those compounds have a lone pair of electrons, and thus are easily adsorbed on the surface of metal, particularly aluminum or its alloy.
Therefore, it is considered that the corrosion resistance is further improved by imidazoles and the like being adsorbed to the metal base exposed at the defective portion of the zirconium layer. It is also considered that the presence of a nitrogen-containing compound having a lone pair of electrons such as an imidazole as an organic substance at the metal / coating film interface improves the adhesion of the coating film. Therefore, it is considered that both the corrosion resistance and the adhesion are improved.

The surface treating agent according to the present invention may further contain other components. For example, pigments, surfactants, silane coupling agents and the like can be mentioned. Examples of the pigment include titanium oxide (TiO ₂ ), zinc oxide (ZnO), zirconium oxide (ZrO), calcium carbonate (CaCO ₃ ), barium sulfate (BaSO ₄ ), and alumina.
Inorganic pigments such as (Al ₂ O ₃ ), kaolin clay, carbon black, iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ) and various coloring pigments such as organic pigments can be used.

Examples of the silane coupling agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, N- [ 2- (vinylbenzylamino)
Ethyl] -3-aminopropyltrimethoxysilane.

A solvent may be used in the surface treating agent of the present invention in order to improve the film forming property of the resin and form a more uniform and smooth coating film. The solvent is not particularly limited as long as it is generally used in coating materials, and examples thereof include alcohol-based, ketone-based, ester-based, and ether-based solvents.

The method of applying the metal surface treatment agent of the present invention to a metal surface is a method of applying the surface treatment agent of the present invention to a degreased metal, heating the object to be coated with hot air and drying after application. Alternatively, a method may be used in which the object to be coated is heated in advance, and then the surface treatment agent of the present invention is hot-applied, and dried using residual heat. The heating temperature is 50 to 250 ° C. in any of the above methods. If the temperature is lower than 50 ° C., the evaporation rate of water is slow and sufficient film-forming properties cannot be obtained, so that the corrosion resistance and coating adhesion are insufficient, and the corrosion resistance and coating adhesion are reduced. On the other hand, when the temperature exceeds 250 ° C., thermal decomposition or the like of the resin occurs, so that the corrosion resistance and the coating adhesion are reduced.

The amount of the surface treating agent to be applied is 1 mg / m 2 after drying.
^It is preferable that the number be ² or more. 1mg attached amount
/ M ² , the corrosion resistance and the paint adhesion deteriorate. However, if the adhesion amount after drying exceeds 5 g / m ² , it is uneconomical as a coating base treatment agent. Preferably 5 mg / m ²
２2 g / m ² . In the above treatment agent, the application method is not particularly limited, a commonly used roll coat,
It can be applied by air spray, airless spray, flow coating, immersion, or the like.

[0021]

EXAMPLES The present invention will be described below in more detail with reference to examples. Example 1 "Jurimer AC-10L" as polyacrylic acid resin
(Manufactured by Nippon Pure Chemical Co., Ltd.) was dissolved in pure water to a concentration of 5.0 g / l and imidazole to a concentration of 2.5 g / l to obtain a surface treating agent of the present invention. An aluminum plate (5082 material) which was degreased and washed (at 50 ° C. for 2 minutes) with this surface treatment agent using a detergent “Surf Cleaner 53” (Nippon Paint Co., Ltd.)
After drying at 80 ° C. for 2 minutes, the adhesion amount after drying is 25 m
g / m ² was applied using a bar coater # 5 and dried. An acrylic paint ("A-55"; manufactured by Nippon Paint Co., Ltd.) was applied to the aluminum plate subjected to the surface treatment with a surface treatment agent using a bar coater # 28 so as to have a film pressure of 5 m, and baked and dried at 240C for 40 seconds. .

The aluminum plate coated with the top coat was cut into 10 grids each vertically and horizontally at intervals of 1 mm with a cutter and subjected to a cascade test for 48 hours (JIS H8).
681, 5.1 to 5.7). After the Cass test, the cross-cut portion was peeled off from the tape, and the corrosion resistance and adhesion were evaluated by the residual ratio (%) of the non-peeled portion. Separately, the storage stability of the surface treatment agent prepared above was confirmed by storing the surface treatment agent in a 40 ° C. incubator for 3 months and then shaking by hand whether or not the treatment agent was gelled. Table 1 shows the evaluation results of the corrosion resistance, adhesion, and storage stability.

Examples 2 to 14 Table 1 shows the types and contents of resins, the types and contents of compounds containing nitrogen atoms having lone electron pairs such as imidazoles, and the amounts of films deposited on aluminum surfaces. (However, γ-aminopropylmethoxysilane was further added to the surface-treating agent of Example 4).
000 ppm), except that
A surface treating agent was prepared and subjected to a coating base treatment. A top coat was applied to aluminum as a base treating agent in the same manner as in Example 1, and the corrosion resistance and adhesion were evaluated in the same manner (however, only in Example 4, the CAS test was performed for 72 hours). The results are shown in Table 1 together with the storage stability of the surface treating agent.

Comparative Example 1 A surface treating agent was prepared in the same manner as in Example 1 except that the amount of imidazole was changed as shown in Table 1. This was coated on an aluminum plate in the same manner as in Example 1 and baked and dried, and then evaluated in the same manner as in Example 1.

Comparative Example 2 Example 5 except that the blending amounts of the acrylic resin and imidazole and the amount of the film adhered were changed as shown in Table 1.
A surface treatment agent was prepared in the same manner as described above. This was coated on an aluminum plate in the same manner as in Example 1 and baked and dried.
Evaluation was performed in the same manner as in Example 1. Comparative Examples 1 and 2
Is shown in Table 1.

Example 15 "Julima AC-10L" as polyacrylic acid resin
5.0 g / l of zirconyl ammonium carbonate (manufactured by Nippon Pure Chemical Co., Ltd.), 5.0 g / l of zirconium ion as zirconyl ammonium carbonate (manufactured by Daiichi Kagaku Kagaku), and 2.5 g / l of imidazole. The surface treatment agent of the present invention was obtained by dissolving in pure water so as to have a concentration. This surface treatment agent
Aluminum plate (508) degreased (50 ° C for 2 minutes) with a detergent "Surf Cleaner" (Nippon Paint Co., Ltd.)
2) at 25 ° C. after drying at 80 ° C. for 2 minutes, and an adhesion amount of 25 mg / m ² (6.5 mg / m ² as zirconium adhesion amount).
m ² ) using a bar coater # 5,
Dried. An acrylic paint ("A-55"; manufactured by Nippon Paint Co., Ltd.) was applied to the aluminum plate, which had been subjected to a surface treatment with a surface treatment agent, using a bar coater # 28 so as to have a thickness of 5 μm, and was baked and dried at 240 ° C. for 40 seconds. .

[0027] Ten aluminum grids each in the vertical and horizontal directions were inserted into the above-coated aluminum plate at intervals of 1 mm with a cutter, and subjected to a cascade test for 72 hours (JIS H8).
681, 5.1 to 5.7). After the Cass test, the cross-cut portion was peeled off from the tape, and the corrosion resistance and adhesion were evaluated by the residual ratio (%) of the non-peeled portion. Separately, the storage stability of the surface treatment agent was measured in the same manner as in Example 1. Table 2 shows the evaluation results of the corrosion resistance, adhesion, and storage stability.

Examples 16 to 23 Table 2 shows the type and content of the resin, the type and content of the compound containing a nitrogen atom having a lone electron pair such as imidazoles, and the amount of the film adhered to the aluminum surface. A surface treating agent was prepared and coated in the same manner as in Example 15 except that the surface treating agent of Example 18 was further modified by adding 3000 ppm of γ-aminopropylmethoxysilane to the surface treating agent. Base treatment was performed. A top coat was applied to aluminum as a base treating agent in the same manner as in Example 15, and the corrosion resistance and adhesion were evaluated in the same manner (however, only in Example 18, the CAS test was performed for 144 hours). The results are shown in Table 2 together with the storage stability of the surface treating agent.

Comparative Example 3 A surface treating agent was prepared in the same manner as in Example 15 except that the amounts of polyacrylic acid and imidazole were changed as shown in Table 2. This was coated on an aluminum plate in the same manner as in Example 15 and baked and dried, and then evaluated in the same manner as in Example 15.

COMPARATIVE EXAMPLE 4 A surface treatment agent was prepared according to the amounts of the acrylic resin, zirconyl ammonium carbonate and imidazole as shown in Table 2, and this mixture gelled before use.

Comparative Examples 5 and 6 A surface treating agent was prepared in the same manner as in Example 15 except that the blending amounts of polyacrylic acid and zirconyl ammonium carbonate and the amount of coating film were changed as shown in Table 2. This was coated on an aluminum plate in the same manner as in Example 15 and baked and dried, and then evaluated in the same manner as in Example 15.

COMPARATIVE EXAMPLE 7 A surface treating agent was prepared by mixing only titanium hydrogen fluoride with polyacrylic acid as shown in Table 2 without using a compound containing a nitrogen atom having a lone electron pair such as a zirconium compound and imidazoles. Prepared. In the case of this surface treatment agent, p
After adjusting the H to 3.5 and immersing the aluminum plate in this for 5 seconds, it was dried at 80 ° C. for 2 minutes. A top coat was applied thereon in the same manner as in Example 15.

Table 2 shows the composition and evaluation results of Comparative Examples 3 to 7. The resins used in the table are as follows: Polyacrylic acid: "Julima AC-10L" (manufactured by Nippon Pure Chemical Co., Ltd.) Acrylic resin: "EM1220" (manufactured by Nippon Paint Co., Ltd.) Urethane resin: "Bontiter HUX -320 "(manufactured by Asahi Denka Co., Ltd.) Olefin resin:" PC-2200 "(manufactured by Shoei Chemical Co., Ltd.) Epoxy resin:" Polysol 8500 "(manufactured by Showa Polymer Co., Ltd.) Polyester resin:" Pesresin A-124G " (Manufactured by Takamatsu Yushi)

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

The metal surface treating agent of the present invention does not contain chromium at all and has better corrosion resistance and coating adhesion after painting than conventional non-chromium treating agents. Particularly, it is suitable as a coating base treating agent for aluminum and aluminum alloys, for example, aluminum blinds.

Claims (4)

[Claims] 1. An aqueous solution or an aqueous dispersion containing a resin in an amount of 0.5 g / l to 200 g / l contains a nitrogen atom having a lone electron pair such as imidazoles, triazines, triazoles, guanines and guanidines. A metal surface treatment agent containing 0.1 g / l to 20 g / l of one or more compounds. 2. An aqueous solution or an aqueous dispersion containing a resin in an amount of 0.5 g / l to 200 g / l contains nitrogen atoms having a lone pair of electrons such as imidazoles, triazines, triazoles, guanines and guanidines. 0.1 g / l to 20 g / l of a compound containing one or more kinds and 0.1 g / l of a zirconium compound as zirconium ion.
A metal surface treatment agent containing 1 to 50 g / l. 3. A method for surface-treating a metal with the metal surface-treating agent according to claim 1 or 2. 4. A metal material surface-treated with the metal surface treatment agent according to claim 1 or 2.