JPH0535227B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to a corrosion inhibitor for aluminum and/or aluminum alloys. For more details, see the general formula below. [In the formula, R represents any one of an amino group, a methyl group, a hydroxyl group, and a carboxyl group, and n represents an integer of 0 to 2. X represents a C ₀ to C ₁₀ linear or branched saturated or unsaturated aliphatic divalent group or a C ₆ to C ₁₀ aromatic divalent group. Y is a hydrogen atom, an alkali metal, or an alkaline earth metal, and m represents the same integer as the valence of Y. ] It is related with the corrosion inhibitor of aluminum and/or aluminum alloy represented by these. (B) Conventional technology In recent years, aluminum and aluminum alloys have been used in a wide variety of fields, and various rust prevention methods have been developed to prevent corrosion in the processing of raw materials and defects caused by corrosion in processed products. is being considered. Depending on the processed product, corrosion resistance is imparted using an anodic oxide film. However, depending on the purpose or shape, products are often manufactured without surface treatment, and a strong surface protection film is formed by a simple dipping treatment or spray coating, and the surface gloss of the processed product. Methods are being considered to prevent the loss of A typical method is protection using a rust preventive agent. In the environment in which the product is used, when exposed to air,
There are various environments such as contact with concrete that has alkalinity, contact with cooling water etc. that forms part of a plant, contact with antifreeze for automobiles, etc., and depending on each environment and purpose, surface treatment and treatment may be required. Rust inhibitors are added. Typical rust preventives include oxide film-forming types such as chromates and phosphates, and chelating agents such as β-diketones, aminophenols, and naphthalene derivatives. Furthermore, carboxylic acids and oxycarboxylic acids are said to have an inhibitory effect on the acidic side. However, there are restrictions due to pollution problems and corrosive environments.
Moreover, it has drawbacks such as the surface condition changing due to the film, so improvements have been desired. (C) Structure of the Invention The product of the present invention suppresses corrosion of aluminum by forming a surface protective film. As a secondary effect, when used on an aluminum base material, it also has the feature of maintaining the surface gloss of the aluminum base material. (d) Effect of the invention The present inventors, in Japanese Patent Application Laid-open No. 58-204183,
Benzothiazolylthiocarboxylic acids, which exhibit excellent rust-preventing effects on iron and copper, have excellent corrosion-inhibiting effects on aluminum over a wide range of pH from 3 to 11. It was discovered that a protective film was formed. The corrosion inhibiting effect of the present invention on aluminum is thought to be due to the strong adsorption of the terminal carboxylic acid and the coordination of the NS atoms of the benzothiazole ring. Because of its high properties, it is possible to preserve and maintain the aluminum surface condition as it was processed. Also
It is effective over a wide range of pH levels from 3 to 11, so it can be used even in alkaline environments. The product of the present invention is a compound synthesized from the sodium salt of 2-mercaptobenzothiazole or the sodium salt of nuclear-substituted 2-mercaptobenzothiazole and a halogenated (alkyl)carboxylic acid or a halogenated arylcarboxylic acid, and is stable. It is a compound with high Some examples include 2-benzothiazolylthioacetic acid, 4-methyl-2-benzothiazolylthioacetic acid, 6-amino-2-benzothiazolylthioacetic acid, 5-carboxy-2-benzothiazolylthioacetic acid, 3-(2-benzothiazolylthio)propionic acid, 3-(4-methyl-2-benzothiazolylthio)propionic acid, 3-(6-hydroxy-
2-benzothiazolylthio)propionic acid, 2-
Benzothiazolylthioformic acid, 3-(4,6-dimethyl-2-benzothiazolylthio)propionic acid, 2-(2-benzothiazolylthio)propionic acid, 2-(4-methyl-2-benzothiazolyl) ruthio)-propionic acid, 5-(2-benzothiazolylthio)valeric acid, 3-(2-benzothiazolylthio(valeric acid, 5-(4-methyl-2-benzothiazolylthio)valeric acid, 3 -(2-benzothiazolylthio)acrylic acid, 3-(4-methyl-2-benzothiazolylthio)acrylic acid, 4-(2-benzothiazolylthio)butyric acid, 10-(2-benzothiazolylthio) ) Undecanoic acid, 10-(4-methyl-2-benzothiazolylthio)undecanoic acid, 2
-(2-benzothiazolylthio)benzoic acid, 2-
Examples include (4-methyl-2-benzothiazolylthio)benzoic acid, 2-(5-carboxy-2-benzothiazolylthio)benzoic acid, and the like. The product of the present invention may be an alkali metal salt or alkaline earth metal salt of these carboxylic acids,
Alkali metals include lithium, sodium,
Examples of the alkaline earth metal include potassium, and examples of the alkaline earth metal include magnesium, calcium, and strontium. In particular, sodium and potassium salts are effective in improving water solubility. The corrosion inhibitor of the present invention can be used in cooling water systems or heating systems in chemical plants that come into contact with water, antifreeze for vehicles, heating medium systems in solar systems, rust preventive oils, paints, rust preventives for concrete, etc. In addition, it can be used for surface coating treatment during aluminum processing and for preservation and protection after processing, as well as for rust prevention during water filling tests on tanks. (E) Example Use city water with the following water quality as the test solution. Pour 350 ml of a solution containing the specified chemical (this invention) into 500 ml of Kolben, and prepare a test piece (aluminum plate A1100) with a 5 mmφ hole in the center. Polish a 50mmφ x 1mm piece with waterproof abrasive paper #320 in advance, degrease it with acetone, dry it, attach it to a stirring rod with a stirring motor, position it in the center of the Kolben liquid part, and place it in a constant temperature bath.
Test for one week while keeping the temperature at 50℃ and rotating the test piece at 120rpm. Water was replenished to maintain a constant liquid level during the water loss. In addition, the test solution has each pH,
The pH was adjusted on the alkaline side with sodium hydroxide and on the acid side with hydrochloric acid. After the test, the corrosion loss of the test piece was measured based on the method of JISK2234 (antifreeze), and from the following formula,
The corrosion protection rate was calculated. In addition, the surface condition was rated ◎ if the surface remained glossy as it was polished, ○ if it was slightly dull, △ if it was slightly whitened, and × if it was whitened. Corrosion protection rate (%) =
Corrosion loss without additives - Corrosion loss with addition of the invention product / Corrosion loss without additives ×
100 Water quality analysis values of city water PH (at 23℃) 7.2 Electrical conductivity (μs/cm) 13.3 M-Alkalinity (CaCO ₃ ) (ppm) 28 Total hardness (CaCO ₃ ) (ppm) 36 Chlorine ion (Cl ^- ) ( ppm) 15 Total iron (Fe) (ppm) 0.34

[Table] (F) Effects of the Invention From the Examples, it was found that the benzothiazolylthiocarboxylic acid of the present invention is an extremely effective corrosion inhibitor for aluminum.

Claims (1)

[Claims] 1. Aluminum and/or represented by the following general formula:
or corrosion inhibitor for aluminum alloys. [In the formula, R represents any one of an amino group, a methyl group, a hydroxyl group, and a carboxyl group, and n represents an integer of 0 to 2. X represents a C ₀ -C ₁₀ linear or branched saturated or unsaturated aliphatic divalent group or a C ₆ -C ₁₀ aromatic divalent group. Y
is a hydrogen atom, an alkali metal, or an alkaline earth metal, and m represents the same integer as the valence of Y. ]