JP2002285361A - Anticorrosives for magnesium-containing metallic material and corrosion inhibition method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide anticorrosives and a corrosion inhibition method by which the corrosion of a magnesium-containing metallic material can effectively be prevented without damaging its excellent metallic luster. SOLUTION: The anticorrosives for a magnesium-containing metallic material contain a compound expressed by the formula (1) or a salt thereof as an effective component, and the corrosion inhibition method uses the anticorrosives: R-CON(CH3 )CH2 COOH (1) [wherein, R denotes a 7 to 19C saturated or unsaturated alkyl group].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosive agent and a method for preventing corrosion of a magnesium-containing metal material, and more particularly, to a method of applying a coating treatment to a magnesium-containing metal material. The present invention relates to an anticorrosion agent used for temporary anticorrosion and the like before treatment and an anticorrosion treatment method.

[0002]

2. Description of the Related Art A magnesium-containing metal material is very easily oxidized, and immediately forms an oxide film even in the air at room temperature.
In addition, since the oxide film easily corrodes upon contact with water containing an oxidizing component, in order to put the magnesium-containing metal material into practical use as a molded product, etc., it is necessary to apply a chemical conversion treatment for anticorrosion before overcoating. Is performed. However, when performing these treatments, after performing degreasing treatment for removing and cleaning surface contaminants and pickling treatment for removing an oxide film, water washing and drying must be performed. Since the paint is left unpainted for a long time, considerable surface oxidation is inevitable.

[0003] Further, as a general antioxidant means applied to a magnesium-containing metal material, a surface is cleaned with a chromate solution, a ferric nitrate solution, a hydrofluoric acid solution or the like, and then subjected to a chromate treatment. In these methods, chemical conversion treatment or anodic oxidation treatment is performed, or overcoating is performed. Among these methods, in the chemical conversion treatment or anodic oxidation treatment, there arises a problem that the metal surface is discolored and the metallic luster is impaired. If a clear coating is used as the top coating, the metallic luster of the magnesium-containing metal material will not be impaired,
Since the moisture resistance and air barrier properties of the clear coating film are not always good, moisture and air permeate the clear coating film, and the magnesium-containing metal material is oxidized within a short period of time, and the volume associated with the formation of oxides The expansion causes peeling of the coating film.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a magnesium-containing metal material without discoloration of the surface or deterioration of the metallic luster. An object of the present invention is to provide an anticorrosive agent capable of forming an excellent anticorrosion film and an anticorrosion treatment method.

[0005]

Means for Solving the Problems The anticorrosive agent according to the present invention which can solve the above-mentioned problems is an anticorrosive agent used for anticorrosion of a magnesium-containing metal material, and is represented by the following general formula (1). The gist lies in that the compound or its salt is contained as an active ingredient. R-CON (CH ₃ ) CH ₂ COOH (1) [where R represents a saturated or unsaturated alkyl group having 7 to 19 carbon atoms] A compound represented by the above general formula (1) is particularly preferable. These are oleoyl sarcosine, lauroyl sarcosine, stearoyl sarcosine and cocoyl sarcosine, which can be used alone or in combination of two or more if necessary.

Further, the anticorrosion treatment method according to the present invention is to improve the corrosion resistance by subjecting a magnesium-containing metal material to a surface treatment using an anticorrosive containing a compound represented by the above formula (1) or a salt thereof as an active ingredient. The gist exists. In carrying out this anticorrosion treatment method, if the surface of the magnesium-containing metal material is previously treated with an aqueous solution of an organic acid and / or an inorganic acid prior to the treatment with the anticorrosion agent, the anticorrosion effect of the anticorrosion agent is obtained. Is further preferred because it can be further increased. Particularly preferred as the organic acid and / or inorganic acid used here are malic acid, gluconic acid, nitric acid, and phosphoric acid, and these can be used alone, or two or more of them can be used as needed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In order to solve the above-mentioned problems, the present inventors have eagerly developed a preservative capable of minimizing corrosion of a magnesium-containing metal material during storage in an unpainted state. As a result of repeated studies, it has been found that the compound represented by the general formula (1) or a salt thereof, in particular, at least one selected from the group consisting of oleoyl sarcosine, lauroyl sarcosine, stearoyl sarcosine and cocoyl sarcosine, or a salt thereof, especially oleoyl sarcosine And its salt form a water-repellent and excellent anticorrosion film on a magnesium-containing metal material to effectively prevent its corrosion, and the water-repellent anticorrosion film is almost colorless and transparent, It has been found that the present invention can effectively utilize the inherent metallic luster, and the present invention has been conceived.

The anticorrosion treatment using this anticorrosion agent can be performed at any time before the coating of the magnesium-containing metal material, and after the degreasing treatment, before or after the chemical conversion treatment. And the chemical conversion treatment can be omitted depending on the application.
In addition, the anticorrosion film formed by the present invention is almost colorless and transparent as described above, and does not impair the metallic luster inherent to the magnesium-containing metal material. It can be used without hindrance, and furthermore, it can be effectively used as an anticorrosive for undercoating to form an arbitrarily colored overcoat by utilizing the excellent anticorrosion performance of the film.

The anticorrosive agent of the present invention is obtained by dissolving the compound represented by the general formula (1) or a salt thereof in water to form an aqueous liquid. In order to effectively exert the anticorrosive action of the anticorrosive agent, the anticorrosive agent is required. The concentration of the compound in the solution was 0.01 g /
It is desirable that the concentration be in the range of not less than 1 liter and not more than 50 g / liter, and more preferable concentration is not less than 0.5 g / liter and not more than 10 g / liter. Even if less than 0.01 g / liter, a water-repellent film is formed, but the amount of the effective anticorrosion component tends to be insufficient, and it is difficult to obtain a satisfactory anticorrosion effect. Further, the higher the concentration of the compound contained in the anticorrosive, the higher the anticorrosive performance is, but the anticorrosive performance is saturated when the concentration of the compound is about 50 g / liter, and even when the concentration is further increased, it becomes higher. Since the corrosion resistance does not improve and only the cost increases, it is desirable to suppress the concentration to about 50 g / liter or less in consideration of economy.

The salt of the compound represented by the general formula (1), which is a main component of the anticorrosive of the present invention, includes amine salts,
Ammonium salts and alkali metal salts are exemplified as preferred ones.

The anticorrosive according to the present invention may further comprise, if necessary, a chelating agent, a surfactant, a preservative, a fungicide, an antifoaming agent, or a known rust inhibitor or non-ferrous metal anticorrosive in addition to the above components. It is also effective to contain each of these compounds to effectively exert their respective effects. Depending on the type of the compound, it is also possible to use an appropriate amount of an organic solvent such as alcohol, ketone or ether as an auxiliary solvent.

The conditions of the anticorrosion treatment using the anticorrosive agent of the present invention are not particularly limited.
It is preferable to make contact with the surface of the magnesium-containing metal material under the condition of time 1 to 600 seconds. The reason is that if the contact (treatment) temperature is lower than 10 ° C., the reactivity between the treatment liquid and the surface of the metal material is insufficient, and it is difficult to form a good anticorrosion film.
This is because if the processing temperature exceeds 0 ° C. and the processing temperature is too high, the metallic luster on the surface to be processed is easily impaired. From such a viewpoint, a more preferable treatment temperature is 30 ° C or more and 60 ° C or less.

If the treatment time is less than 1 second, the adsorption of the effective anticorrosion component on the surface to be treated is insufficient, so that it is difficult to obtain a satisfactory anticorrosion performance. Even if it is longer, not only the anticorrosion performance is not further improved but the treatment efficiency is lowered, but also the metallic luster of the treated metal material surface tends to be impaired, which is not preferable.

There is no particular limitation on the method in which the anticorrosive is brought into contact with the magnesium-containing metal material.
Any method such as a spray method and a roll method may be employed.

In treating the magnesium-containing metal material with the above-mentioned anticorrosive agent of the present invention, it is effective to perform a degreasing treatment or an acid pickling as a pretreatment step. The degreasing method includes trichloroethylene, ethanol, methanol, acetone and the like. Various methods such as solvent degreasing with an organic solvent such as the above or alkali degreasing can be employed.

The pickling treatment is very effective as a preliminary treatment immediately before the treatment with the anticorrosive. That is, if the treatment with the anticorrosive agent is performed immediately after the thin oxide film on the surface of the metal material is removed by the pickling treatment, the rust prevention film is formed on the surface of the clean metal material from which the oxide film has been removed. This is because the adhesion between the magnesium-containing metal material and the anticorrosion film is further enhanced, and an excellent anticorrosion effect is exhibited.

The acid used for pickling may be any of organic acids and inorganic acids, and organic acids such as formic acid, acetic acid, malic acid, citric acid, gluconic acid, oxalic acid, tartaric acid, benzoic acid and phthalic acid. Inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, and hydrofluoric acid can be used, and these can be used alone or, if necessary, in combination of two or more kinds. Particularly preferred among these acids are malic acid, gluconic acid, nitric acid and phosphoric acid.

The magnesium-containing metal material to which the anticorrosive agent and the anticorrosion treatment method of the present invention are applied includes pure magnesium and a magnesium alloy. Specific examples of the magnesium alloy include Mg-A1-Zn, Mg-A1 -M
n, Mg-Al-Si, Mg-Al-Re, Mg-Zn
And Mg-Al-Zn-Mn. The shape and size of these magnesium-containing metal materials are not limited at all, and include plate materials, wire materials, rod materials, pipe materials, and various other molded products.

The feature of the anticorrosion treatment method according to the present invention is that
If magnesium or magnesium alloy is exposed on part or all of the surface of these metal materials, all of them will be effectively exhibited. Therefore, the present invention also relates to a molded article in which a magnesium-free metal material and a magnesia-containing metal material are combined and assembled. Is processed. Further, those magnesium-containing metal materials may be subjected to a shot blast treatment, a surface roughening treatment with an acid or an alkali, or a surface activation treatment using ozone, plasma, or the like. Conventional surface treatment such as treatment or chemical conversion treatment may be applied.

[0020]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to experimental examples. However, the present invention is not limited to the following experimental examples, and the present invention is not limited thereto. Modifications may be made and all of them are included in the technical scope of the present invention.

Experimental Examples Table 1 shows examples and comparative examples of the anticorrosive agent and the anticorrosion treatment method according to the present invention. Details of the treatment method performed are as follows, using the following test magnesium-containing metal plate, the surface polishing of the test plate → degreasing treatment → pickling treatment → anticorrosion treatment → drying in order, or in it Partially omitted.

Test magnesium-containing metal plate: JIS H
Magnesium alloy AZ91D specified in 2222 (die casting plate: 40 mm × 40 mm ×
10 mm) Surface polishing of the test plate: dry polishing using AA240 abrasive paper, degreasing treatment I: alkaline degreasing: using an alkaline aqueous solution containing 100 g / l of NaOH and 1 g / l of a surfactant, Is immersed in 50 to 55 ° C. for 5 minutes to perform degreasing, and then washed with water. II: Solvent degreasing: The test material is immersed in acetone, ultrasonically cleaned, and then wiped off with acetone. C. to evaporate and remove acetone. Pickling treatment: Immerse the test material in an aqueous solution of malic acid 1 g / l for 10 seconds at 20.degree. C. Anticorrosion treatment: 55% of each test material in the following anticorrosive agent Immerse at ６０60 ° C. for 1 minute. Drying: Each immersed test material obtained above is taken out of the anticorrosion treatment bath, washed with water and dried at 50 ° C. for 10 minutes with a warm air dryer.

[Processing method] Processing method A ... ++ I ++ Processing method B ... ++ II ++ Processing method C ... ++ II Processing method D ... ++ I Processing method F ++ I.

[Anticorrosive used (all aqueous solutions)] 1) Oleoyl sarcosine: 2 g / liter + DCHA:
1 g / liter 2) Oleoyl sarcosine: 2 g / liter + NaOH:
0.2 g / l 3) Oleoyl sarcosine: 2 g / l + TEA:
0.8 g / liter DCHA: dicyclohexylamine TEA: triethanolamine.

The anti-corrosion performance of each of the obtained treated metal materials was evaluated by the following three methods: (a) an under-house exposure test, (b) a wet test, and (c) a cycle test. Table 2 shows the results.

[Corrosion prevention test method] a) Under-eave exposure test: After exposing each of the test pieces subjected to anti-corrosion treatment under the eaves for a predetermined period, the evaluation was performed according to the following criteria.: No change at all, O: Very slight discoloration , Δ: slight discoloration, ×: sharp discoloration, XX: severe discoloration or corrosion, b) Wet test: after holding each test piece in a warm air type constant temperature room at 49 ± 1 ° C. for a predetermined time, the appearance is as described above. Visual evaluation based on the same criteria as in a), c) Cycle test: 1 liter wide-mouthed bottle, 3 for humidity control
10 ml of 5% glycerin water was added, and each test piece was placed on the top of the rubber stopper approximately 5 mm from the bottom with a stainless steel hook.
Hang it so that it comes to the position of 0 mm. In this test piece,
After repeating 5 cycles with [40 ° C. × 16 hours → 5 ° C. × 8 hours] as one cycle, the test specimen is dried, and the corrosion state is visually evaluated from the surface appearance of the test specimen according to the same criteria as in the above a).

[0027]

[Table 1]

[0028]

[Table 2]

In Examples 1 to 5 and Comparative Examples 1 to 3, the color tone of the formed film is all colorless and transparent, but the film subjected to chromate treatment, which is a conventional anticorrosion treatment, has a brown color. It is colored.

Further, in Examples 1 to 5, all show extremely excellent anticorrosion properties as compared with Comparative Examples 1 to 3 in which no anticorrosion treatment is performed after the pickling treatment.

[0031]

According to the conventional chromate treatment method widely used for the corrosion prevention of magnesium-containing metal materials, the anticorrosion film becomes brown and the metal luster is remarkably impaired. However, if the anticorrosive agent and the anticorrosion treatment method of the present invention are adopted, it is possible to form a colorless and transparent film having excellent corrosion resistance on the surface of the magnesium-containing metal material. Excellent corrosion resistance can be provided while maintaining the inherent metallic luster. Moreover, the active ingredient of the anticorrosive used in the present invention is low in toxicity, does not cause environmental pollution, etc., has high safety, is excellent in handling and stability, and is extremely practical.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Fujita 3--3-3 Hinagahigashi, Yokkaichi City, Mie Prefecture Inside Yokkaichi Plant, Chubu Kyrest Co., Ltd. 3-3-3 Chubu Killest Co., Ltd. Yokkaichi Plant (72) Inventor Kyoko Hashimoto 3-3-3 Hinagahigashi Yokkaichi City, Mie Prefecture 3-3-3 Chubu Killest Co., Ltd. Yokkaichi Plant F-term (reference) 4K062 AA01 BC21 FA20

Claims (5)

[Claims] An anticorrosive for a magnesium-containing metal material, comprising a compound represented by the following general formula (1) or a salt thereof as an active ingredient. R-CON (CH ₃ ) CH ₂ COOH (1) [where R represents a saturated or unsaturated alkyl group having 7 to 19 carbon atoms] 2. A compound represented by the general formula (1):
The anticorrosive for magnesium-containing metal material according to claim 1, which is at least one selected from the group consisting of oleoyl sarcosine, lauroyl sarcosine, stearoyl sarcosine and cocoyl sarcosine. 3. A method for anticorrosion treatment of a magnesium-containing metal material, comprising subjecting the magnesium-containing metal material to a surface treatment using the anticorrosion agent according to claim 1 or 2. 4. The anticorrosion treatment method according to claim 3, wherein prior to the treatment with the anticorrosive agent, the surface of the magnesium-containing metal material is treated in advance with an aqueous solution of an organic acid and / or an inorganic acid. 5. The anticorrosion treatment method according to claim 4, wherein the organic acid and / or the inorganic acid is at least one selected from the group consisting of malic acid, gluconic acid, nitric acid, and phosphoric acid.