JPS58204183A - Rust preventive - Google Patents

Abstract

PURPOSE:To obtain a rust preventive having a stable effect on both of iron and copper, by synthesizing a compound from the Na salt of benzothiazole and a specified carboxylic acid as starting materials. CONSTITUTION:This rust preventive is a compound represented by formula I and synthesized from the Na salt of 2-mercaptobenzothiazole or the Na salt of nuclear substituted 2-mercaptobenzothiazole and halogenated alkylcarboxylic acid or halogenated arylcarboxylic acid. The compound is carboxylic acid having a benzothiazole ring or an alkali metallic salt, an alkaline earth metallic salt, an ammonium salt or an amine salt of the carboxylic acid, and it has superior rust preventive power to iron and copper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rust preventive agent represented by the following general formula that is particularly effective against both iron-based and copper-based metals.

[In the formula, R represents any one of an amino group, a methyl group, and a hydroxyl group, and n is an integer of 0 to 2.

X represents a straight chain or branched saturated or unsaturated aliphatic divalent group of C5 or an aromatic divalent group of C6 to CIO. Y is a water curtain atom, an alkali metal.

It is an alkaline earth metal or a quaternary ammonium group, and m represents the same integer as the valence of Y. ] Conventionally used iron-based rust inhibitors include sodium nitrite, phosphorus-based compounds, and chromium-based compounds. However, these rust inhibitors, for example, have the problem of carcinogenicity due to nitro-compounds (2) produced by reaction with amines in the case of sodium nitrite, the toxicity of chromium ions in the case of chromium-based agents, and the toxicity of chromium ions in the case of phosphorus-based agents. Due to disadvantages such as eutrophication caused by the compound, its use is becoming restricted.However, at present there is no comparable effective water-soluble rust inhibitor for iron based sodium dinitrite. It is widely used because it is not yet available.However, sodium nitrite is not an effective rust preventive agent for copper-based metals, and it is used in combination with iron-based metals and copper-based metals. It is inconvenient, and in terms of sustainability, it has a short lifespan because it is easily decomposed by microorganisms. Similarly, aliphatic carboxylic acids and fatty acids are Group dicarboxylic acids are also well known, but in reality they are not widely used because they are inferior in effectiveness.Benzotriazoles and There are derivatives thereof, 2-mercaptobenzothiazole salts, etc., but a drawback of these is that they are not effective against iron-based metals.

In view of the shortcomings of conventional products, and after extensive research, the present inventors have developed a rust inhibitor that is extremely effective and maintains a stable effect on both iron-based and copper-based metals. That is, it is a compound consisting of a carboxylic acid having a benzothiazole ring, or its alkali metal or alkaline earth metal salt, or ammonium salt or amine salt,
Although they are both carboxylic acid-based, they exhibit much stronger rust-preventing power than conventionally known carboxylic acids, and it is surprising that they can also exhibit extremely stable rust-preventing power against copper-based metals. That's true.

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 alkylcarboxylic acid or a halogenated arylcarboxylic acid, and has low stability. It is a high compound. As an example,
2-Benzothiadylthioacetic acid, 4-methyl-2-benzothiadylthioacetic acid, 6-amino-2-benzothiadylthioacetic acid, 6-hydroxy1-2-benzothiadylthioacetic acid, 2- Penzothi ≠ fried thioformic acid, 3-(2-benzothiadylthio)-propionic acid, 3-(4-methyl-2-
benzothiadylthio)-propionic acid, 3-(6-amino-2-benzotheadylthio)-propionic acid, 3-(
6-Hydroxy-2-benzothiadylthio)-propionic acid, 3-(4゜6-dimethyl-2-benzothiadylthio)-propionic acid, 2-(2-benzothiadylthio)-propionic acid, 2- (4-Methyl-2-benzothiadylthio)-propionic acid, 5-(2-benzothiadylthio)-valeric acid, 3-(2-benzothiadylthio)-valeric acid, 5-(5,6 -cyhydroxy-2-benzothiadylthio)-valeric acid, 5-(4-methyl-2-benzothiadylthio)-valeric acid.

3-(2-benzotheazylthio)-acrylic acid.

3-(4-Methyl-2-benzothiadylthio)-acrylic acid, 4-(2-benzothiadylthio)-butyric acid, 4-(
4-Methyl-2-benzothiadylthio)-butyric acid, 4-(
6-amino-2-benzothiadylthio)-butyric acid, 2-(
Examples include 2-benzothiadylthio)-benzoic acid, 2-(4-methyl-2-benzotheadylthio)-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, and examples of the alkali metal include lithium, sodium, and potassium. In particular, sodium and potassium salts are most effective in improving water solubility.

In the product of the present invention, by introducing a quaternary ammonium group in addition to these metals, the effect can be enhanced due to improved water solubility and the antirust action of the ammonium group. Examples include -H-Z, where 2 is ammonia and alkanolamines such as monoethanolamine, jetanolamine, triethanolamine, and monoethylamine.

aliphatic amines such as diethylamine and tributylamine;
Examples include alicyclic compounds such as dicyclohexylamine and cyclohexylamine, heterocyclic compounds such as morpholine and pyridine, and polyethylene polyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepestamine.

The rust preventive agent of the present invention can be used in cooling water systems or heating systems of chemical plants that come into contact with water, and antifreeze for vehicles.

Touran stem (heat transfer system, anti-corrosion oil, paint).

Rust inhibitor for concrete, high water content hydraulic fluid, especially iron-based.

It is effective in antifreeze for vehicles used in places where there are many combinations of copper-based metals, and in heating medium systems in solar systems.

Naturally, the use of the product of the present invention is not limited to this. In addition, the effect can be further improved by using the rust preventive agent of the present invention together with a known rust preventive agent.

This will be explained below by giving synthesis examples and examples.

Synthesis Example 20 parts of 2-mercaptobenzothiazoal sodium salt was added to 200 parts of methanol, dissolved, heated to 40°C, and stirred. Separately, a solution of 14 parts of β-chloropropionate sodium salt dissolved in methanol was added dropwise over 30 minutes.
After the dropwise addition is completed, the mixture is heated and refluxed to complete the reaction. Next, methanol is distilled off, the obtained crystalline substance is dissolved in water again to make it acidic and cooled, and the obtained crystalline substance is washed with sufficient cold water (2) and dried to a melting point of 141-143°C. White crystalline substance (3
-(2-Benzothiazylthio)propionic acid 323 parts (
Yield: 93%). (Literature value 142-143°C) The obtained product (sodium dioxide was reacted with 3-
(2-benzothiadylthio)-propionic acid sodium salt is used in the examples.

The compounds of Examples 2 to 12 below were also obtained by the same method, and each was used in the Examples as a sodium salt, potassium salt, or amine salt.

As a comparative example, no additives and sodium nitrite.

2-mercaptobenzothiazole sodium salt.

Benzotriazole, triethanolamine, sepacic acid sodium salt and triethanolamine salt were used. The test liquid used was city water with the following water quality: 5001T17? A solution prepared by adding a prescribed drug (product of the present invention) to Kolben
Test piece with TrLe inserted and a 5 da hole in the center (steel plate 5PCC, 5096X 1 mm, steel plate TCuP
1,505/X 1 mm) was polished in advance with waterproof abrasive paper #320, degreased with 10% NaOH, washed with water, and then re-washed. □Keep the test piece at 50℃ in a constant temperature bath at 12O
Test for one week with rotation at r-pPm. During this period, water was replenished to maintain a constant liquid level.

Corrosion degree (mdd) is determined from the corrosion weight loss of the test piece after one week.
) is calculated.

Corrosion degree (mdd) = corrosion weight loss (■) / test days (
day) 4 test piece surface area (dn1') The test results obtained are shown in the table.

[Water quality analysis value of city water]

From the examples, it was found that a carboxylic acid salt having a benzothiazole ring is an extremely effective rust preventive agent for iron-based and copper-based metals.

patent applicant Sanshin Chemical Industry Co., Ltd. 426-

Claims (1)

[Claims] Represents one group of the general formula, and n represents an integer of O to 2. X represents a linear or branched saturated or unsaturated aliphatic divalent group with Co<5 or an aromatic divalent group with C6<10. Y is a hydrogen atom or an alkali metal. It is an alkaline earth metal or a quaternary ammonium group, and m represents the same integer as the valence of Y. ] Rust preventive agent.