JPH11181578A - Metallic surface treating agent and treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film having uniform and good appearance and corrosion resistance without using harmful sexavalent chromium by incorporating it with Al, Si and organic acid or inorganic acid. SOLUTION: As a feeding source of Si, sodium silicate, potassium silicate, lithium silicate or coloidal silica of <=50 nm grain size preferably used. As the inorganic acid, one or more kinds among hydrochloric acid, sulfuric acid, nitric acid, hydrogen peroxide and phosphoric acid are preferably used, and as the organic acid, one or more kinds of carboxylic acids among formic acid, acetic acid, succinic acid, diglycolic acid or the like are preferably used. In the case the metallic surface treating agent is furthermore added with fluorine, the appearance of the film is made bright and is made better. The preferable compsn. of the treating agent is composed of 0.01 to 200 g/L Al and 0.01 to 250 g/L alkali silicate or coloidal silica, 0.1 to 100 g/L fluorine compd. (in the case of the addition) and 0.1 to 100 g/L inorganic or organic acid, and the pH is preferably regulated to <=6.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a zinc or zinc alloy and a metal material plated with the same.
More particularly, the present invention relates to an iron component plated with zinc and a zinc-based alloy.

[0002]

2. Description of the Related Art In general, zinc or zinc-based alloy plating (hereinafter referred to as zinc plating) is most widely used as a method for preventing rust on iron-based materials and parts. However, when zinc-plated iron-based materials and components are used as they are, white rust, which is the rust of zinc, is immediately generated, so that it is common practice to further form a protective film. A chromate film treatment is generally used as a protective film usually applied to zinc plating, and the chromate film treatment is further divided into three types: electrolytic chromate treatment, coating type chromate treatment, and reactive type chromate treatment. are categorized. The chromate treatment is applied not only to zinc but also to aluminum, cadmium, magnesium and the like.

[0003] Chromate films are widely used because they are inexpensive and can easily obtain practical corrosion resistance. However, all chromate treatments use harmful hexavalent chromium. In recent years, hexavalent chromium eluted from products has a serious problem because it has an adverse effect on human bodies and the environment. This is a difficult problem since the chromate film is a film exhibiting corrosion resistance due to hexavalent chromium in the film.

Various inventions have been filed for solving the pollution problem of hexavalent chromium. For example, a treatment in which titanium is combined with titanium and one of phosphoric acid, phytic acid, tannic acid and hydrogen peroxide is applied. Japanese Patent Application Laid-Open No. 52-92836 describes the formation of a film by a liquid, and describes the formation of a film by a treatment solution combining an oxidizing substance, a silicon compound, and one of Ti, Zr, Ce, Sr, V, W, and Mo. Japanese Patent Application Laid-Open No. 9-53192, JP-A-57-5875, which describes a treatment with a treatment solution having a pH of 1 to 6 containing a phosphate of Mo and aluminum and an organic or inorganic acid, and phosphoric acid and Zr or Ti.
Japanese Patent Application Laid-Open No. 9-143752 which describes a treatment with a treating solution of fluorinated and phosphorous or hypophosphorous acid.

Although these inventions can be noted in that they do not use hexavalent chromium, these treatment methods do not necessarily impart sufficient corrosion resistance to the metal surface to a practical level. It is not satisfactory as an alternative treatment to chromate treatment containing chromium. For example, J
In the salt spray test specified in ISH 2731, the stable corrosion resistance is as described in JP-A-52-9283.
6, about 12 to 48 hours according to JP-A-57-5875 and JP-A-9-143752.
But it is around 48-60 hours. This corrosion resistance is 1/1 of that of commonly used colored chromate or black chromate.
Only 0-1 / 2. An even greater problem is that the cost is 5 to 10 times that of the conventional colored chromate, so that one of the features of the chromate is to lose the splendid cost performance. The cost increase of an order of magnitude for the inexpensive process, chromate, halved its appeal and was the first obstacle to the transition to alternative technologies for chromate processors.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to form a protective film on the surface of zinc or a zinc alloy without using harmful hexavalent chromium and providing a film having a uniform and good appearance and corrosion resistance. To generate. In particular, it is to obtain excellent cost performance which is an obstacle to the practical application of the alternative technology that has been invented so far.

[0007]

Means for Solving the Problems In order to solve the problems in the prior art, the inventors of the present invention have made intensive studies and found that a rust preventive film can be formed by a liquid composition containing aluminum, silicon and an organic or inorganic acid. Have found that these problems can be solved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, 0.01 to 200 g / L
Preferably 0.1 to 20 g / L of aluminum and 0.0
1 to 250 g / L, preferably 1 to 50 g / L of alkali silicate or colloidal silica;
Hydrochloric acid, sulfuric acid, nitric acid, hydrogen peroxide or phosphoric acid, or an organic acid as an inorganic acid of from 150 to 150 g / L, preferably from 1 to 25 g / L, and from 0.1 to 100 g / L, preferably from 1 to 20 g / L. By forming a protective film with a metal surface treating agent having a pH of 6.5 or less containing at least one of carboxylic acids such as formic acid, acetic acid, succinic acid and diglycolic acid, corrosion resistance comparable to conventional colored chromate is obtained. Turned out to be.

The method of supplying aluminum is not particularly specified, and if it is supplied with a salt such as aluminum sulfate or aluminum nitrate, a component of an inorganic acid other than aluminum can be supplied, which is convenient. As a source of silicon, sodium silicate, potassium silicate, lithium silicate, or colloidal silica having a particle size of 50 nm or less is preferable. For example, sodium silicate No. 3 can be used. When fluorine is further added to these compositions, the appearance becomes bright and a good appearance is obtained. Examples of the source of fluorine include hydrofluoric acid, ammonium fluoride, borofluoric acid, and sodium fluoride. Further, by containing an organic or inorganic acid, the treatment is stable, and sulfuric acid is particularly effective for obtaining a uniform appearance. The pH is preferably 6.5 or less, more preferably pH 3 or less. For adjusting the pH, an acid species already added or an alkali component such as alkali hydroxide or ammonia is used.

Although the function of each component is not clear, it is presumed that aluminum and silicon compounds form the skeleton of the film, and that fluorine and other acids are involved in etching of the substrate and uniform formation of the film. Presumed. Further, phosphoric acid and other organic acids can also be expected to have an effect as a thickening agent for the film.

The treatment of the present invention can be carried out under the same conditions as conventional chromate. For example, the treatment temperature is 20 to 70 ° C.
The processing time is 30 to 120 seconds, and the processing equipment can be the same as the one used for conventional gloss chromate, etc., and can be introduced with the conventional feeling. .

[0012] The compositions of the present invention can also include various materials as set forth in conventional alternative techniques. For example, T
Examples include metals such as i, Zr, Ce, Sr, V, W, and Mo; organic substances such as phytic acid, tannic acid, cyanuric acid, thiol compounds, and thioglycolate; and silane coupling agents. The purpose of these additions is to change the appearance in addition to corrosion resistance and the like. For example, it is possible to increase the color by adding a metal or to provide a new color by adding an organic substance. When adding these substances, it is necessary to pay attention to the cost performance, which is one of the features of the present invention, in consideration of the cost increase due to the addition.

After the treatment with the treatment liquid of the present invention, a protective film can be formed by two-step treatment with a treatment agent such as an inorganic or organic coating agent or an inorganic-organic composite coating agent.
Colloidal silica, silicone compounds, acrylic resins, epoxy resins, melamine resins,
Alkyd resins, fluororesins, phenolic resins, polyamide resins, urethane resins and mixtures thereof. The corrosion resistance is further improved by using the present invention as a coating base and applying a coating such as anionic electrodeposition coating, cationic electrodeposition coating, or electrostatic coating.

Although the prior art has not solved the problem of cost in addition to the performance, this problem can be almost completely cleared in the present invention. That is, the chemical used for the conventional substitute film is, for example, 1600 to 170 in the case of titanium trichloride.
0 yen / kg, ammonium vanadate 2500-300
0 yen / kg, sodium tungstate 2,500-3
000 yen / kg, ammonium tungstate 3000
4,000 yen / kg, sodium molybdate 3000
~ 3500 yen / kg, ammonium molybdate 350
Although it is very expensive compared with 0 to 4000 yen / kg and 490 to 500 yen / kg of chromic acid used for chromate, according to the present invention, aluminum sulfate 382 to 412 yen / kg, aluminum chloride 380 to 380 400 yen / kg, sodium silicate 37 yen / kg (above "12966 chemical products" published by Kagaku Kogyo Nippo), which is cheaper than conventional chromate.

Further, in the conventional invention, not only the supply chemical itself is more expensive than chromate, but also some processing liquids have a drawback that these processing liquids themselves are poor in stability and have a short liquid life. In the case of a very short object, it is updated almost every day to several days, and a reduction in the total cost due to running cannot be expected, resulting in a very expensive process. In addition, the labor, labor costs and time for frequent bathing cannot be ignored, but the present invention has a liquid life equal to or longer than that of chromate, so that the total cost including running costs can be maintained at the same level as conventional chromate.

[0016]

The present invention will be described below with reference to examples. In the test, the test piece was subjected to an appropriate pretreatment such as degreasing and immersion in nitric acid, and then subjected to the treatment according to each of the following examples.
The prepared test piece was put into a salt spray tester. Unless otherwise stated, a test piece was a 50 × 100 × 1 mm iron plate.
Table 1 shows the white rust occurrence time in each test.

[0017]

[Table 1]

Example 1 A galvanized iron sheet was prepared by adding 7.5 g / L of aluminum sulfate.
No.3 sodium silicate 70g / L, 4.5g 67.5% nitric acid
/ L for 30 seconds in an aqueous solution of pH 3.0 containing / L to form a film. Example 2 A zinc-plated iron plate was coated with 8.5 g / L of aluminum nitrate,
No. 3 sodium silicate 90g / L, 62.5% nitric acid 5.5g
/ L for 50 seconds in an aqueous solution of pH 2.6 containing / L to form a film.

EXAMPLE 3 A zinc-plated iron plate was prepared by using aluminum sulfate 5 g / L, No. 3 sodium silicate 50 g / L, and ammonium fluoride 25 g / L.
L, and dipped in an aqueous solution of pH 2.8 containing 3 g / L of 67.5% nitric acid for 40 seconds to form a film. Example 4 A zinc-plated iron plate was coated with aluminum nitrate 10 g / L, cataloid SI-3035 g / L, sodium fluoride 12
g / L, 9% g / L of 75% sulfuric acid, 2% g / L of 35% hydrochloric acid, and immersed for 1 minute in a treatment solution adjusted to pH 3.0 to form a film and produce a test piece.

Example 5 A zinc-plated iron plate was treated with aluminum nitrate 6 having a pH of 1.6.
g / L, No. 3 sodium silicate 20 g / L, hydrofluoric acid 5 g /
L, 1 g / L of phosphoric acid, and 2 g / L of sulfuric acid were immersed for 2 minutes to form a film. Example 6 A zinc-plated iron plate was coated with aluminum sulfate 9 g / L, sodium silicate 13 g / L, and acidic ammonium fluoride 12 g / L.
L, a treatment solution adjusted to pH 2.3 containing 10 g / L of 60% nitric acid and 11 g / L of 75% sulfuric acid for 1 minute to form a film.

Example 7 A zinc-plated bolt (M5, 30 mm below neck) was treated with aluminum sulfate 10 g / L, No. 3 sodium silicate 25 g / L,
The film was immersed in a treatment solution having a pH of 2.8 containing 5 g / L of borofluoric acid and 8 g / L of 60% nitric acid for 1 minute to form a film. Example 8 An iron plate plated with a zinc-iron alloy was coated with 10 g / L of aluminum nitrate having a pH of 2.5, 25 g / L of sodium silicate No. 3, 10 g / L of ammonium ammonium fluoride, 1.5 g / L of hydrochloric acid, 6
The film was immersed in a treatment solution containing 6 g / L of 0% nitric acid and 4 g / L of 75% sulfuric acid for 70 seconds to form a film.

Example 9 A zinc-plated iron plate was treated with aluminum sulfate 1 having a pH of 3.0.
5 g / L, No. 3 sodium silicate 20 g / L, hydrofluoric acid 8 g /
L, phosphoric acid 2 g / L, acetic acid 2 g / L, 67.5% nitric acid 5
After immersion in a treatment solution containing g / L for 75 seconds and forming a film, a test piece was prepared by immersion in a treatment solution containing 80 g / L of potassium silicate and 7 g / L of potassium hydroxide for 30 seconds. Example 10 A zinc-plated iron plate was treated with aluminum nitrate 1 having a pH of 2.6.
5 g / L, No. 3 sodium silicate 30 g / L, hydrofluoric acid 10 g
/ L, phosphoric acid 3g / L, acetic acid 1g / L, 75% sulfuric acid 5g
/ L was immersed in a treatment solution containing 85 L for 85 seconds, and the film after the film was formed was immersed in Cosmercoat No. 9001 (manufactured by Kansai Paint) and coated to prepare a test piece.

COMPARATIVE EXAMPLE 1 A test piece was a zinc-plated iron sheet whose surface had not been subjected to any treatment, and the time until the occurrence of white rust in a salt spray test (JIS Z 2371) was examined. Comparative Example 2 20 g / L of 35% hydrogen peroxide and 10 g / 62% of nitric acid
L, an iron plate galvanized with a pH 1.3 treatment liquid containing 1.0 g / L of titanium sulfate was subjected to a chemical conversion treatment at a liquid temperature of 20 ° C. for 45 seconds.

Comparative Example 3 30 g / L of 35% hydrogen peroxide and 15 g / L of 62% nitric acid
L, colloidal silica 70 g / L, titanium sulfate 0.3 g
An iron plate galvanized with a pH 1.6 treatment solution containing / L was subjected to a chemical conversion treatment at a solution temperature of 20 ° C. for 45 seconds. Comparative Example 4 50 g / L of 35% hydrogen peroxide, 5 g / L of 62% nitric acid,
Colloidal silica 100 g / L, titanium sulfate 0.3 g /
L, a galvanized iron plate was treated with a treatment solution of pH 1.5 containing 15 g / L of 75% phosphoric acid for 45 seconds.

Comparative Example 5 30 g / L of 35% hydrogen peroxide, 5 g of ammonium fluoride acid
/ L, titanium sulfate 2.3 g / L, 75% phosphoric acid 15 g /
L, a galvanized iron plate with a treatment solution containing 2 g / L of hypophosphorous acid was subjected to a chemical conversion treatment for 45 seconds. Comparative Example 6 A test piece was prepared by immersing a galvanized iron plate in a treatment solution containing 12.1 g / L of sodium molybdate and 14.7 g / L of 75% phosphoric acid.

Comparative Example 7 A test piece was prepared by immersing a galvanized iron plate in a treatment solution containing 12.1 g / L of sodium molybdate and 14.7 g / L of 75% phosphoric acid for 2 minutes. Comparative Example 8 Sodium molybdate 0.1 mol / L, phosphoric acid 0.1 mol / L
A test piece was prepared by immersing a galvanized iron plate in a treatment solution containing 15 mol / L at 60 ° C. for 2 minutes.

Comparative Example 9 A test piece was prepared by immersing a galvanized iron plate in a treatment solution containing 22 g / L of sodium molybdate and 15.7 g / L of aluminum monophosphate for 2 minutes. Comparative Example 10 Sodium vanadate 15 g / L, 75% phosphoric acid 20 g
/ L, a zinc-plated iron plate was immersed in a treatment solution of pH 2 containing 35 g / L of sodium nitrate for 2 minutes to prepare a test piece.

[0028]

By using the aqueous solution specified in the present invention, a harmful hexavalent chromium is not used, and a strong film which is insoluble on the metal surface by the same processing equipment, processing conditions and processing method as conventional reactive chromate. Can be generated. As a result, not only general users who are concerned about elution of hexavalent chromium from processed products, but also the health effects of chromate manufacturers and chromate processors who have been exposed to the hazards of chromate and the effects on wild animals The problem can be solved.

Claims (8)

[Claims] 1. A metal surface treating agent containing aluminum and silicon and further containing one or more organic acids or inorganic acids. 2. The metal surface treating agent according to claim 1, further comprising fluorine. 3. The metal according to claim 1, wherein the inorganic acid is at least one selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, hydrogen peroxide and phosphoric acid, and the organic acid is a carboxylic acid. Surface treatment agent. 4. The metal surface treating agent according to claim 1, wherein the silicon is provided by sodium silicate, potassium silicate, lithium silicate, or colloidal silica having a particle size of 50 nm or less. . 5. The aluminum of 0.01 to 200 g
/ L, 0.01 to 250 g / L of the silicon and 0.1 to 100 g / L of the organic acid or inorganic acid, and optionally 0.1 to 100 g / L of the fluorine, pH
The metal surface treating agent according to any one of claims 1 to 4, wherein 6.5 is the following. 6. A method for immersing a metal substrate in the metal surface treating agent according to any one of claims 1 to 5 to produce a metal substrate having a protective film formed on the surface. 7. The method according to claim 1, wherein the metal substrate is zinc, nickel, copper,
7. The method of claim 6, wherein the method is selected from the group consisting of silver, iron, cadmium, magnesium, aluminum, and alloys thereof. 8. After forming a metal substrate having a protective film formed on the surface by the method according to claim 6 or 7, further treating with a inorganic or organic coating agent or an inorganic-organic composite coating agent. A method for producing a metal substrate having a protective film formed on a surface.