JP2001342578A - Metal surface treatment agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment agent giving superior corrosion resistance and adhesion of a coated film to metals especially aluminum or aluminum alloys suitable for automobils. SOLUTION: The surface treatment agent for metals includes a resin containing a carboxyl group (a) of 0.06-3%, a zirconium compound (b) of 0.07-3.6% as Zr, and an imidazole silane compound (c) of 0.06-3%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal surface treating agent, and more particularly, to a metal surface treating agent suitable for aluminum or aluminum alloy for automobiles.

[0002]

2. Description of the Related Art In general, aluminum or aluminum alloy used for automobile bodies, household appliances, steel furniture, etc. is subjected to a surface treatment before painting for the purpose of improving corrosion resistance and coating film adhesion. ing. This is also called a chemical conversion treatment. From the viewpoints of performance, workability, cost and the like, the chromate treatment has been widely performed so far. JP-A-11-6078 discloses a chemical conversion treatment solution for aluminum containing hexavalent chromium ions, fluorozirconium ions, silicon compounds and fluorine ions.

[0003] In recent years, awareness of environmental preservation has been increasing, such as stricter regulations on the amount of chromium in wastewater.
In the case of a chromate treatment, when the obtained film is thick, a problem of coloring or the like occurs. JP-B-56-33468 discloses a surface treatment agent for aluminum containing zirconium and / or titanium, phosphate and fluoride.
Although it is used for food cans, it can form a colorless and transparent coating film on the surface of aluminum and has a resistance not to be blackened even under boiling water.

JP-A-11-106945 discloses a metal ion such as zirconium ion, a fluoro acid, a silane coupling agent, and an acidic metal surface treating agent comprising 2 to 50 polymerized units of a water-soluble polymer component. Have been.
JP-A-6-177535 discloses a surface treatment agent for copper foil comprising an imidazole silane compound and a bistrialkoxysilyl compound having a specific structure. Japanese Patent Application Laid-Open No. 9-2959992 discloses an organosilicon compound obtained by reacting vinylimidazole with mercaptosilane.

However, from the viewpoint of corrosion resistance,
It was not enough to substitute for a chromate film. In recent years, because aluminum is lightweight,
For the purpose of improving fuel efficiency and operability, aluminum or aluminum alloys have been used in automobile bodies and the like, and pre-coated boards having excellent corrosion resistance that can be used in automobiles are desired. ing.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal surface treating agent which is particularly suitable for aluminum or aluminum alloy for automobiles and which has excellent corrosion resistance and adhesion of a coated film after coating. is there.

[0007]

According to a first aspect of the present invention, a carboxyl group-containing resin (a) is used in an amount of 0.06 to 3 on a weight basis.
%, The zirconium compound (b) is 0.07 to
3.6% and imidazole silane compound (c) were added to 0.0%
It is a metal surface treatment agent characterized by containing 6 to 3%. In the second invention, the carboxyl group-containing resin (a) is 0.06 to 3% by weight, the zirconium compound (b) is 0.07 to 3.6% as Zr, and the substituted or unsubstituted imidazole ( A metal surface treatment agent comprising 0.03 to 2.4% of d) and 0.03 to 2.4% of amino-modified silicone (e).

Hereinafter, the present invention will be described in detail. The metal surface treating agent of the first present invention comprises, on a weight basis, 0.06 to 3% of carboxyl group-containing resin (a), 0.07 to 3.6% of zirconium compound (b) as Zr, and imidazole silane. It contains 0.06 to 3% of the compound (c).

The carboxyl group-containing resin (a) contributes to the corrosion resistance and adhesion of the coated film after coating.
The carboxyl group-containing resin (a) is not particularly limited as long as it is soluble alone or in water by amine neutralization, but is preferably obtained by polymerizing a monomer containing 30% by weight or more of a monomer containing a carboxyl group. preferable.
If it is less than 30% by weight, the adhesion may be poor.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, itaconic acid, maleic acid and fumaric acid. The monomer other than the carboxyl group-containing monomer is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n, i, and t- (Meth) acrylic esters such as butyl, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate; styrenes such as styrene and α-methylstyrene; and amides such as acrylamide and methacrylamide. Can be. The monomers used for the carboxyl group-containing resin (a) may be used alone or in combination of two or more of the above.

The amine used for the neutralization is not particularly restricted but includes, for example, alkanolamine. As the carboxyl group-containing resin (a),
A water-soluble acrylic resin obtained by copolymerizing (meth) acrylic acid is preferable, and Jurima AC-10 manufactured by Nippon Junyaku Co., Ltd.
It is also possible to use a commercially available product such as Sulmer AC-10.

The carboxyl group-containing resin (a) is contained in the metal surface treating agent of the first invention in an amount of 0.06 by weight.
３3%. If it is less than 0.06%, the coating film after coating is inferior in corrosion resistance and adhesion. If it exceeds 3%,
Cohesive failure of the film occurs, resulting in poor adhesion. Preferably, it is 0.9 to 1.8%.

In the first aspect of the present invention, the zirconium compound (b) contributes to the corrosion resistance and adhesion of the coated film after coating. The zirconium compound (b) includes zircon hydrofluoric acid (H ₂ ZrF ₆ ), and
Ammonium zircon hydrofluorate ((NH ₄ ) ₂ Zr
Salts of zircon hydrofluoric acid such as F ₆ ); ammonium zirconate oxycarbonate ((NH ₄ ) ₂ ZrO (CO
₃ ) ₂ ) and the like. Preferably, H ₂ Z
It is a fluorozirconium compound having four or more fluorine atoms such as rF ₆ .

The zirconium compound (b) is used as Zr in the first metal surface treating agent of the present invention on a weight basis.
0.07 to 3.6%. If it is less than 0.07%, the coating film after coating is inferior in corrosion resistance and adhesion. 3.
If it exceeds 6%, cohesive failure of the film occurs, resulting in poor adhesion. Preferably, it is 1-2%.

In the first aspect of the present invention, the imidazole silane compound (c) contributes to the adhesion of the coated film after coating. Examples of the imidazole silane compound (c) include imidazole and a 3-glycidoxypropyl trialkoxysilane compound (where the alkoxy group has 1 to 3 carbon atoms).
) At 80 to 200 ° C (JP-A-6-177535); a radical reaction between vinylimidazole and a mercaptotrialkoxysilane compound (alkoxy group having 1 to 5 carbon atoms) Compound obtained by reacting at 40 to 100 ° C. in the presence of an initiator (JP-A-9-2959992)
Can be mentioned. Specifically, commercially available products such as imidazole silane IS-1000 and imidazole silane EM-1000 manufactured by Japan Energy Co., Ltd. can be used.

The imidazole silane compound (c) is
In the first metal surface treating agent of the present invention, 0.00.0
It contains 6 to 3%. If it is less than 0.06%, the adhesion of the coated film after coating is poor. If it exceeds 3%, the effect is not changed, but the cost is increased. Preferably, 0.9 to
1.8%.

The metal surface treating agent of the second invention is characterized in that the carboxyl group-containing resin (a) is contained in an amount of 0.06 to 3 on a weight basis.
%, The zirconium compound (b) is 0.07 to
3.6% of substituted or unsubstituted imidazole (d) in 0.
0.3 to 2.4% and the amino-modified silicone (e) in 0.1%.
It contains 0.3 to 2.4%. As the carboxyl group-containing resin (a) and the zirconium compound (b), those exemplified in the first aspect of the present invention can be used.

In the second invention, a substituted or unsubstituted imidazole (d) and an amino-modified silicone (e)
Contributes to the adhesion of the coated film after painting. As the substituted or unsubstituted imidazole (d), an imidazole monomer can be used. Examples of the group which may be substituted in imidazole (d) include an alkyl group having 1 to 5 carbon atoms. The substituted or unsubstituted imidazole (d) contains 0.03 to 2.4% by weight of the metal surface treating agent of the second invention. If it is less than 0.03%, the adhesion of the coated film after coating is poor. If it exceeds 2.4%, cohesive failure of the film occurs, resulting in poor adhesion. Preferably, 0.6-1.
5%.

The amino-modified silicone (e) has a structure in which one or more aminoalkyl groups are bonded to the terminal and / or side chain of the siloxane main chain. Examples of the alkyl in the aminoamyl group include a linear or branched alkyl group having 1 to 6 carbon atoms. The molecular weight of the amino-modified silicone (e) is not particularly limited, and includes, for example, 200 to 50,000.

The amino-modified silicone (e) may be amino-modified silicone oil KF39 manufactured by Shin-Etsu Chemical Co., Ltd.
3, X-22-161A, and aminopropyl-terminated polydimethylsiloxane DMS-A11, manufactured by Nitrogen
S-A12, DMS-A15, DMS-A21, DMS
-A32; aminopropylmethylsiloxane-dimethylsiloxane copolymer AMS-132, AMS-15
2, AMS-162; diaminopropylmethylsiloxane-dimethylsiloxane copolymer AMS-233; aminoethylaminoisobutylmethylsiloxane-dimethylsiloxane copolymer AMS-242; aminoethylaminopropylmethoxysiloxane-dimethylsiloxane copolymer ATM-1112, ATM-1322, etc. Can also be used.

[0021] The amino-modified silicone (e) is
In the metal surface treatment agent of the present invention, 0.03 to
It contains 2.4%. If it is less than 0.03%, the adhesion of the coated film after coating is poor. If it exceeds 2.4%, cohesive failure of the film occurs, resulting in poor adhesion. Preferably,
0.6-1.5%. In the second aspect of the present invention, it is preferable to add an equal amount of the substituted or unsubstituted imidazole (d) and the amino-modified silicone (e),
This is not necessary.

The metal surface treating agent of the first and second aspects of the present invention preferably further contains hydrofluoric acid (f). The hydrofluoric acid (f) contributes to forming a uniform and sufficient film by etching the oxide film on the surface of the object to be coated, particularly in the case of aluminum or aluminum alloy. The above-mentioned hydrofluoric acid (f) is 0.01 to
Contains 1%. If it is less than 0.01%, a uniform and sufficient film cannot be formed, and if it exceeds 1%, the etching becomes excessive and the film is hardly formed. Preferably, it is 0.05 to 0.5%.

The metal surface treating agent according to the first and second aspects of the present invention comprises a carboxyl group-containing resin (a), a zirconium compound (b), an imidazole silane compound (c) or a substituted or unsubstituted imidazole. It can be prepared by dissolving (d) and the amino-modified silicone (e) and, if desired, hydrofluoric acid (f) and other additives in water in a corrosion-resistant container.

The metal to which the metal surface treating agents of the first and second aspects of the present invention are applied is preferably aluminum or an aluminum alloy. The aluminum or aluminum alloy is first degreased by removing oil and dust on the surface by alkali washing or acid washing, and then thoroughly washed off the degreasing liquid by washing with water and / or hot water. Alternatively, the metal surface treatment agent of the second invention is applied. Thereafter, a primer coating is performed to prepare a precoated plate.

Examples of the treatment method using the metal surface treating agent of the first and second inventions include a roll coating method, a dipping method, and a spray method. Preferably, it is based on a roll coating method. Then 50
It is preferable to perform drying and baking by heating at about 200 ° C. for about 5 seconds to 5 minutes. Although the amount of the obtained film is not particularly limited, for example, the Zr amount is 1 to 50 in a dry film amount.
mg / m ² .

Aluminum or an aluminum alloy is generally susceptible to thread rust corrosion after painting, but those treated with the metal surface treatment agent of the first or second invention have excellent performance. , Especially excellent in corrosion resistance. Furthermore, since excellent corrosion resistance is maintained even when the cylindrical drawing is performed thereafter, it is particularly suitable for a precoated plate of an automobile or the like.

[0027]

The present invention will be described in more detail with reference to the following examples.
As will be described, the present invention is limited to only these examples.
is not. Parts represent parts by weight. Example 1 40% by weight H_Two ZrF₆ Ion-exchanged water in 56.9 parts of solution
43.1 parts were added and mixed to obtain 10% by weight of H as Zr._Two 
ZrF₆ An aqueous solution was obtained. Julimer AC-10S (Japan
Add 75.0 parts of ion-exchanged water to 25.0 parts.
Then, mix and add 10% by weight water-soluble acrylic resin aqueous solution.
Obtained. Imidazole silane IS-1000 (Japan D
90.0 parts of ion-exchanged water to 10.0 parts
And mix to give a 10% by weight aqueous solution of imidazole silane.
Obtained. Ion-exchanged water 9 in 9.1 parts of 55% by weight HF solution
0.9 part was added and mixed to obtain a 5% by weight aqueous HF solution.
Was. Stainless steel with Teflon (registered trademark) processing
Put 78.3 parts of ion-exchanged water in the car,
Gradually at room temperature while stirring with a roller (200 rpm)
The above H _Two ZrF₆ 7.2 parts of aqueous solution, HF aqueous solution
2.5 parts, water-soluble acrylic resin aqueous solution 6 parts, imidazo
Add 6 parts of an aqueous solution of silane in this order and stir until uniform.
After stirring, a surface treating agent was obtained.

Aluminum flat plate (5182PO-1.
0t) with 2% by weight of surf cleaner 322N-8
(Nippon Paint Co., Ltd.), spray pressure 1.5kg
Degreased by spraying at 65/70 ° C / cm ^{2 for} 5 seconds. After degreasing, the product was spray-washed at room temperature for 5 to 10 seconds, dipped in hot water at 50 ° C for 1 to 2 seconds, and dried at 80 ° C for 1 minute. The surface treating agent obtained above was applied by a roll coater at a coating speed of 60 m / min.
It was 5 g / m ² . Material maximum temperature (PMT) 10
Bake at 0 ° C for 30 seconds. After cooling, Flexcoat #
5000 (polyester / urethane; Nippon Paint Co., Ltd.) was applied by a roll coater so as to have a dry coating film of 15 g / m ² and a film thickness of about 15 μm.
Second baking was performed. The amount of coating after coating is as follows: X-ray spectrometer 3 for Zr and Si.
070 (manufactured by RIGAKU). The amount of Zr is 10 mg / m ² for the dry film, and the amount of Si is 0.6 mg / m ² .
m ² . The resin content was measured by baking at 500 ° C. (muffle furnace) for 10 minutes and removing the film. The resin content is
The dry film yield was 9 mg / m ² .

The obtained aluminum-coated flat plate was subjected to a cup forming speed of 6.5 mm / sec and a maximum material elongation of 60 using a metal sheet deep drawing tester type 142 (manufactured by Exelin Co.).
% Was subjected to cylindrical drawing. Each of the aluminum-coated flat plate and the one subjected to the cylindrical drawing was evaluated according to the following evaluation method. The results are shown in Table 1.

1. Water resistance evaluation A test plate was immersed in warm water at 40 ° C. for 240 hours, and 100 cross cuts with a width of 2 mm were cut. 2. Evaluation of salt and hot water resistance A cut was placed on a test plate, immersed in a 5% NaCl solution at 55 ° C. for 240 hours, and the coating film peeling width from the cut (one side)
Was measured. 3. Evaluation of Yarn Rust Property The test plate with the cross cut was subjected to four cycles of one cycle consisting of 24 hours of salt spray and 240 hours of 40 ° C. under 70% RH. The length of yarn rust from the cross cut was measured per 10 cm of the cross cut.

4. Cycle Corrosion Test (CCT) A cross cut reaching the substrate confirmed by the energization method was inserted into a test piece using a cutter knife. The test piece was set in a composite corrosion tester, and a corrosion test was performed according to the following conditions.
A cycle was performed. After 50 cycles, the blister width on one side from the cross cut was measured. Maximum blister width 3.5
mm or less was rated as ○. Corrosion test conditions Wet 40 ° C 95% RH, 2 hours Salt spray 35 ° C 5% NaCl, 2 hours dry 60 ° C, 1 hour wet 50 ° C 95% RH, 6 hours dry 60 ° C, 2 hours wet 50 ° C 95% RH, 6 hours drying 60 ° C, 2 hours Low temperature -20 ° C, 3 hours

Examples 2 to 4 Surface treatment agents were prepared in the same manner as in Example 1 except that the contents of Zr, water-soluble acrylic resin and imidazole silane in H ₂ ZrF ₆ were as shown in Table 1. Then, painting and evaluation were performed. The results are shown in Table 1. In Table 1, PAA
Represents a water-soluble acrylic resin, and Im-Si represents imidazole silane.

Example 5 10 parts of imidazole was added to 90 parts of ion-exchanged water and mixed to obtain a 10% by weight aqueous solution of imidazole. 10 parts of amino-modified silicone KF393 (manufactured by Shin-Etsu Chemical Co., Ltd.) were added to 90 parts of ion-exchanged water, and mixed to obtain a 10% by weight aqueous solution of amino-modified silicone. 78.3 parts of ion-exchanged water is placed in a Teflon-treated stainless steel beaker, and the H ₂ ZrF ₆ aqueous solution 7.2 obtained in Example 1 is slowly stirred at room temperature while stirring with a magnetic stirrer (200 rpm).
Part, HF aqueous solution 2.5 parts, water-soluble acrylic resin aqueous solution 6
, 3 parts of the above imidazole aqueous solution and 3 parts of the amino-modified silicone aqueous solution were added in this order, and the mixture was stirred until it became uniform to obtain a surface treating agent. Using this surface treatment agent,
Coating and evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

Examples 6 to 8 Surface treatment was carried out in the same manner as in Example 5 except that the contents of Zr, water-soluble acrylic resin, imidazole and amino-modified silicone in H ₂ ZrF ₆ were as shown in Table 1. An agent was prepared, painted and evaluated. The results are shown in Table 1. In Table 1, Im indicates imidazole and Si indicates amino-modified silicone.

Comparative Examples 1 to 13 Except that the contents of Zr of H ₂ ZrF ₆ , water-soluble acrylic resin, and imidazole silane or imidazole and amino-modified silicone were as shown in Table 1,
A surface treating agent was prepared in the same manner as in Example 1 or Example 5, and coating and evaluation were performed. The results are shown in Table 1.

Comparative Example 14 A test plate which had been subjected to a phosphoric acid chromate treatment according to the following method was prepared using Alsurf 407/47 (manufactured by Nippon Paint Co., Ltd.) as a surface treatment liquid. Aluminum flat plate (5
182P-O 1.0t) by using a 2% by weight surf cleaner 322N-8 (manufactured by Nippon Paint Co., Ltd.) at a spray pressure of 1.5 kg / cm ² at 65 to 70 ° C for 5 seconds, Defatted. After degreasing, at room temperature
Spray water for 10 seconds, spray pressure 1.0 kg / cm with Alsurf 407/47 (3% / 0.4% by weight)
^{2. A} phosphoric acid chromate treatment was performed by spraying at 50 ° C. for 5 seconds (Cr amount: 20 mg / m ² ). Flexcoat # 5000 (polyester / urethane; Nippon Paint Co., Ltd.) was dried with a roll coater to a dry coating of 15 g /
m ² and a film thickness of about 15 μm.
Baking was performed at 0 ° C. for 60 seconds. The obtained test plate was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0037]

[Table 1]

As shown in Table 1, the aluminum test plates treated with the metal surface treating agents of Examples 1 to 8 exhibited excellent corrosion resistance equal to or higher than that of the chromate phosphate treatment. Further, even when cylindrical drawing was performed thereafter, excellent corrosion resistance was maintained.

[0039]

The metal surface treating agent of the present invention can be suitably used for aluminum or aluminum alloy for automobiles since a coating film having excellent corrosion resistance and adhesion can be obtained after coating.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 83/08 C08L 83/08 101/08 101/08 (72) Inventor Satoshi Nishimura Minami Shinagawa, Shinagawa-ku, Tokyo 4-1-1-15 Nippon Paint Co., Ltd. (72) Inventor Kenji Tsuge 4-1-1-15 Minato Shinagawa, Shinagawa-ku, Tokyo Japan (72) Inventor Satoshi Miyamoto 4 Minamishinagawa, Shinagawa-ku, Tokyo No. 1-115 Japan Paint Co., Ltd. F term (reference) 4J002 BC041 BC071 BC091 BG011 BG041 BG051 BG061 BG131 BH021 CP092 DD018 DD037 EX076 GH02 4K044 AA06 AB02 BA21 BB01 BC02 BC04 CA53

Claims (7)

[Claims] 1. A carboxyl group-containing resin (a) having a content of 0.06 to 3%, a zirconium compound (b) having a Zr content of 0.07 to 3.6% and an imidazole silane compound (c) having a content of 0.06 to 3% by weight. A metal surface treatment agent characterized in that the metal surface treatment agent is contained in an amount of from 6 to 3%. 2. A carboxyl group-containing resin (a) in an amount of 0.06 to 3%, a zirconium compound (b) in an amount of 0.07 to 3.6% as Zr, and a substituted or unsubstituted imidazole (d) on a weight basis. And 0.03 to 2.4% of amino-modified silicone (e). 3. The metal surface treating agent according to claim 1, wherein the carboxyl group-containing resin (a) is a water-soluble acrylic resin. 4. The metal surface treating agent according to claim 1, wherein the zirconium compound (b) is a fluorozirconium compound having four or more fluorine atoms. 5. The method according to claim 1, wherein said hydrofluoric acid (f) is 0.01 to 1
The metal surface treating agent according to claim 1, wherein 6. The metal surface treating agent according to claim 1, wherein the applied metal is aluminum or an aluminum alloy. 7. Aluminum or aluminum alloy,
The metal surface treating agent according to claim 6, which is used for automobiles.