CS195174B1 - Method of producing water-soluble corrosion inhibitor - Google Patents

Description

The present invention relates to a process for the preparation of a corrosion inhibitor for the preservation of metallic products, in particular steel, against atmospheric corrosion, which can be applied from aqueous solutions either alone or in admixture with other substances. It can preferably be used, in particular, for short-term, in-process corrosion protection, possibly as an additive to a radiator and lubricants for grinding and polishing surfaces.

Various substances are known which are dissolved or emulsifiable in water and are used as atmospheric corrosion inhibitors for temporary corrosion protection. They include, in particular, alkali nitrites, chromates, phosphates, silicates, alkanolamines, alkylarylsulfonic acid salts and alkali metal hydroxides, · Salts of benzoic acid and salicylic acid, salts of organic and inorganic acids and alkanolamines, or mixtures of higher substances and others.

Said corrosion inhibitors have some drawbacks which, if misused, cause inter-operative corrosion and t-acre to increase manufacturing costs and cause economic losses.

For example, nitrites, chromates, phosphates, silicates, benzoates and salicylans require very accurate dosing, especially in the presence of chlorides and sulphates, because in insufficient concentrations they accelerate corrosion events. In addition, nitrites and chromates are harmful to health, similar phosphates in terms of how they affect the growth of microflora in watercourses. Another drawback of these substances is that they do not have film-forming properties. The salts of alkylarylsulfonic acids are sensitive to overdose; furthermore, the quality of these substances is of great importance, which can vary with each manufactured dose. Salts of amines and organic acids have similar disadvantages.

The aforementioned drawbacks are largely solved by the corrosion inhibitor according to the invention, which consists in the reaction of a-aminocaproic acid or caprolactam or caprolactam oligomers or a mixture thereof with organic acids, preferably dicarboxilic acids, preferably sebacic acid, urea and / or alkyl derivatives. urea in the presence of polyhydric alcohols, preferably glycerin, and polybasic inorganic acids, preferably boric acid at a temperature of 50 ° C to 175 ° C, and the resulting product is neutralized with amines or alkanol amines, preferably mono-, di-, triethanolamine or a mixture of these. of substances. ''

The resulting product is a pasty substance with a drop point of 35-43 ° C, good water-soluble to a clear solution, pH of a 2% aqueous solution of such a product in the range of 7.5-8.1.

The reaction mixtures prepared according to the invention are characterized in that they inhibit atmospheric corrosion of iron and its alloys.

The corrosion inhibitor of the invention is applied by immersing the steel components in a 1 to 2% aqueous solution of the product at 20 to 80 ° C for about 2 minutes. After drying, a fine transparent protective film is formed on the surface of the steel parts to protect the steel parts from atmospheric corrosion for a sufficiently long time. In this way, the preserved low carbon steel sheets under accelerated corrosion test conditions are free of corrosion for 300 to 670 hours, with samples of the same material; Preserved in 1% triethanolamine solution, spot and area corrosion was detected as early as 24 hours.

The process for preparing the inhibitor of the invention is illustrated in greater detail in the examples below:

Example 1 mol of t-aminocaproic acid, 0.2 mol of boric acid. and 0.2 moles of glycerin are homogenized at 90 ° C for 10-15 minutes. 1 mol of sebacic acid is added to the mixture and the mixture is homogenized for a further 20 minutes. After this time, 0.4 mol of urea is added to the mixture and allowed to react at room temperature.

110 ° C 120-150 minutes. After this time, the mixture was neutralized with 1.1 mol of monoethanolamine. The reaction product is a pasty substance.

Example2

Preparation procedure as in Example 1, only z-aminocaproic acid is replaced by 1 mole of caprolactam. The product is a pasty substance.

Example 3 ad moles of caprolactam-caprolactam oligomer (calculated as caprolactam),

0.5 mol of boric acid and 0.5 mol of glycerol · are homogenized at 105 ° C for 15 minutes.

0.55 mol of sebacic acid is added and the mixture is homogenized for 20 minutes.

After this time, 0.7 mol of urea was added to the mixture and allowed to react at 135 ° C for 120 minutes. After this time, the mixture

Claims (1)

SUBJECT Process for preparing a corrosion inhibitor, characterized in that the ω-aminocaproic acid or caprolactam or caprolactam oligomers or mixtures thereof are reacted with organic acids, preferably dicarboxilic acids, preferably sebacic acid, with urea and / or alkyl derivatives to neutralize 0.6 moles of monoethanolamine. The reaction yields the desired product. Example 4 The process and the materials used as in Example 3, but only for neutralization, technical triethanolamine was used. Example5 The procedure and materials used as in Example 3, but instead of 0.7 mol of urea, were used 0.7 mol of methyl urea. Example 6 Procedure and materials used as in Example 3, but instead of glycerol, 0.5 mol of pentaerythritol was used. Ex. ad 7 Procedure and materials used as in Example 3, only 0.5 mol of pentaerythritol was used instead of glycerin and 1.1 mol of caprile acid was used instead of sebacic acid. Example 8 Procedure and substances used as in Example 3, but instead of glycerin, 0.5 mol of diethylene glycol. An advantage of the process of preparing the corrosion inhibitor of the present invention is that it is possible to utilize the water-insoluble caprolactam oligomers, which fall off as a by-product in the caprolactam polymerization, and the cost of processing such oligomers for fibrous purposes is laborious and costly. BACKGROUND OF THE INVENTION urea in the presence of polyhydric alcohols, preferably glycerin and polybasic inorganic acids, preferably boric acid at 50 to 175 ° C, and the resulting product is neutralized with an amine or an alkanol with an amino acid, preferably a mono-, di-, briethanol, or a mixture thereof.