JPS5946313B2 - anti-rust - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rust preventive agent for steel.

General water-soluble rust preventives, whether organic or inorganic, maintain their effectiveness when steel is immersed in the aqueous solution. For example, if exposed indoors where there are atmospheric humidity and temperature changes even if there is no direct exposure to wind or rain, apply a rust preventive solution with a brush or spray, especially inside a closed container. When the product becomes wet with water, the rust-preventing ability is significantly reduced even if the concentration of the water-soluble rust preventive agent is considerably increased.

On the other hand, rust preventive oil can maintain its rust preventive effect for quite a long time even when exposed indoors, but in order to remove it, it is necessary to completely wash away the water-soluble rust preventive with water. On the other hand, since it requires a complicated degreasing process and equipment for degreasing using alkaline agents or solvents, and processing the waste liquid, the anti-corrosion method for target equipment that avoids oil is a major hindrance in terms of process elimination and cost reduction. There is.

In order to eliminate such obstacles, a homopolymer of a hydrocarbon having a double bond selected from carboxylic acids or carboxylic acid anhydrides, and/or a copolymer of the same hydrocarbon and an olefinic hydrocarbon having 2 to 6 carbon atoms is used. We first proposed a so-called water-soluble film-type rust preventive agent, which is based on a water-soluble resin film obtained by mixing a polymer with an alkaline solution and modifying it. A water-soluble rust preventive agent that can be removed by washing with water.
It has been shown to be effective in preventing rust on the inner surfaces of heat exchangers and tank pipes in chemical plants, etc.

However, when applying this anti-rust agent to the inner surface of small-diameter pipes such as heat exchangers, especially those with various bends, by dipping it or connecting it to a pump and circulating it, it takes time to drain it because of its high viscosity. Otherwise, there was a problem that an excessive amount remained in the pipe. In addition, when applied to the outside surface of the pipe, depending on the manufacturing process, pipes coated with this rust preventive agent are piled up one after another, but since this rust preventive agent is drying, it is difficult to move the pipes again. It had the disadvantage that the contact surface peeled off and needed to be repainted. The present inventors have conducted extensive research in order to provide a rust preventive agent that is water-soluble, has low viscosity without using a water-soluble resin, and is non-drying, and does not have the above-mentioned problems. As a result, we have completed the present invention.

That is, the present invention consists of an aqueous solution of (1) a neutralized salt of an aliphatic dibasic acid having 6 to 12 carbon atoms and a polyvalent amine having 2 to 6 ethylene groups or methylene groups at a weight ratio of 10 to 50. anti-rust.

(2) A water-soluble rust preventive agent is added to an aqueous solution of a neutralized salt of an aliphatic dibasic acid having 6 to 12 carbon atoms and a polyvalent amine having 2 to 6 ethylene or methylene groups at a weight ratio of 10 to 50. Rust preventive agent added.

The main points are as follows.

Examples of the aliphatic dibasic acid having 6 to 12 carbon atoms used in the present invention include adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, and the ethylene group for neutralizing this acid Or methylene group from 2 to
Examples of the polyvalent amine having 6 include diethylenetriamine,
triethylenetetramine, tetraethylenepentamine,
Examples include ethyleneamines such as pentaethylenehexamine, and methyleneamines such as trimethylenediamine, tetramethylenediamine, hexamethylenediamine, and hexamethylenetetramine.

As the above amines, ethylene group or methylene group is
The reason why we selected the polyvalent amine having .
This is because, for example, monoamines such as diethanolamine are ineffective.

The above aliphatic dibasic acid has ethylene or methylene group 2
An aqueous solution with a weight ratio of 10 to 50 of a compound neutralized with a polyvalent amine having ~6 has a viscosity of less than 24% at 25°C compared to the previously proposed water-soluble film-type rust inhibitor. Since it is a centistoke, it can be easily discharged during circulating flow coating inside a pipe, and the amount left inside is small, making it economical.

In addition, water-soluble antirust agents added to the above neutralized salt include various alkali metal salts of phosphoric acid, nitrous acid, boric acid, and silicic acid, or various amine salts, or benzoic acid, paratertiary benzoic acid, nitrophthalic acid, Alkali metal salts such as soda and potassium of organic acid compounds such as mercaptobenzothiazole, or various amine salts such as monoethanolamine and synchlohexylamine are used.

Generally, the amount of this type of water-soluble rust preventive agent added is suitably in the range of 0.05 to 5.0% based on the neutralized salt. 0.
This is because if it is less than 0.05%, it has almost no effect, and if it is added more than 5%, the effect does not increase proportionally, which is uneconomical.

Since the rust preventive agent of the present invention is composed of the composition described above, (1) it is non-drying even when applied to the surface of steel, and it can be applied to the surface of pipes and not piled up. too,
Since the film is extremely thin and non-drying, phenomena such as peeling do not occur.

(2) Rust-preventing power remains effective for a long time under conditions of indoor exposure and closed humid atmosphere, and after use, it can be completely dissolved by running water through it or immersing it in water.

It is effective and can be used as a rust preventive agent for general steel products.

Hereinafter, the present invention will be explained in more detail by giving specific examples.

The composition of the present invention uses sebacic acid, suberic acid, adipic acid, etc. as an aliphatic dibasic acid having 6 to 12 carbon atoms, and polyhydric acid having 2 to 6 ethylene or methylene groups to neutralize the aliphatic dibasic acid having 6 to 12 carbon atoms. Compositions using triethylenetetramine, tetramethylenediamine, pentaethylenehexamine, etc. as amines, and compositions to which a water-soluble rust preventive agent was added were prepared. Then, it was dipped in a mild steel polishing plate (SS-41150 x 75 x 17 ftm) and pulled up.
A two-month rust prevention test was conducted by suspending the product in a box placed outdoors. The composition and the results of the rust prevention test are shown in Table 1.
Further, the results of comparative examples are shown in Table 2. As shown in the present results, for the composition of the present invention, the concentration of fatty acid neutralized salt was 10
When the weight ratio is lower than that, rusting is observed in a short period of time, but when the weight ratio is higher than 20, the effect lasts for more than one month. Even if the weight ratio is increased to 50 or more, the effect will be increased by X, but it will not be economical, and the viscosity will increase and the workability will decrease.

Addition of water-soluble rust inhibitors generally enhances effectiveness, depending on the type.

In addition, during the rust prevention test in a box set outdoors, rain does not hit the test piece, but water soluble This is a fairly harsh testing method for anti-corrosive or oil film-based rust preventives, and indoor exposure is thought to last for more than four times as long, depending on the season of the test.

In addition, the test piece used in this test or the test piece newly coated with the composition of the present invention by spray painting was left in a thermostat at 60°C for 24 hours, and then immersed in room temperature water. After a few minutes, the adhered composition will completely dissolve.
No residue was observed.

Claims (1)

[Scope of Claims] 1. An aqueous solution of a neutralized salt of an aliphatic dibasic acid having 6 to 12 carbon atoms and a polyvalent amine having 2 to 6 ethylene or methylene groups in a weight ratio of 10 to 50. Rust agent. 2. A water-soluble rust preventive agent is added to an aqueous solution of a neutralized salt of an aliphatic dibasic acid having 6 to 12 carbon atoms and a polyvalent amine having 2 to 6 ethylene groups or methylene groups at a weight ratio of 10 to 50. Rust preventive agent.