CS253367B1 - Mixed evaparating corrosion metal inhibitor - Google Patents

Abstract

The solution relates to mixed evaporation corrosion inhibitor of metals and their alloys. The aim of the solution is an effective evaporation corrosion inhibitor of metals and their alloys based on benzoic acid salts and acid salts dialkylphosphorous, whose substance it consists of 0.1 to 50 parts benzoic acid salts with ammonium hydroxide and / or organic hydroxide amines, singly or in mixture, of 0.1 to 0.1 80 parts by weight of dialkylphosphoric acid salts with ammonium hydroxide and / or organic amines, singly or in mixtures, optionally 0.001 to 5 parts by weight 1,2,3-benzotriazole and / or it derivatives, individually or in admixture.

Description

The present invention relates to a mixed evaporative corrosion inhibitor of metals and their alloys in approximately neutral aqueous environments, especially atmospheric conditions.

The influence of corrosion occurring in an approximately neutral aqueous environment, especially in atmospheric conditions, is considerably unfavorable for metal products, since corrosion products are formed on their surface, which depreciate them functionally and visually. A number of temporary protection methods and means are used to reduce or eliminate these negative phenomena, of which the use of evaporative-type metal corrosion inhibitors is of great importance.

Most of the known evaporation inhibitors are characterized by high inhibitory activity, but are used on an industrial scale for their hygienic defectiveness.

This type of evaporation inhibitor is based on the anion of nitrous acid and chromic acid, in particular dicyclohexylamine nitrite, diisopropylamine nitrite and cyclohexylamine chromene. Also, amiwf / Z salt of 3,5-dinitrobenzoic acid having considerable hygienic limitations.

Among the harmless evaporation inhibitors, octadecylamine, 1,2,3-benzotriazole and its alkyl or hydroxy derivatives, ammonium benzoate and a number of mixed types are known, but they are characterized by relatively low protective efficacy, low volatility especially at low temperatures or in the absence of moisture and in some cases poor solubility

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The aforementioned drawbacks in the art are largely eliminated by the mixed evaporative corrosion inhibitor of metals and their alloys on the basis of the mixture of the benzoic acid salts and the dialkylphosphoric acid salt according to the invention, characterized in that the inhibitor contains 50 to 0.1 parts by weight of salt benzoic acid with ammonium hydroxide and / or organic amines, singly or in admixture, 0.1 to 80 parts by weight of a salt of dialkylphosphoric acid with ammonium hydroxide and / or organic amines, individually or in a mixture, optionally 0.001 to 5 parts by weight 2,3-benzotriazole and / or derivatives thereof, singly or in admixture.

According to the invention, dialkylphosphoric acid means an acid of the general formula wherein R 1 and R ₂ are alkyls of carbon numbers up to C 4, especially dimethylphosphoric acid, formed as a distillation residue in the production of dimethylphosphide.

Organic amines according to the invention are understood to mean alkanolamines, in particular 2-aminoethanol H ₂ N-CH ₂ -CH ₂ -OH, furthermore cyclic primary and / or secondary amines, in particular morpholine, piperidine and cyclohexylamine.

The 1,2,3-benzotriazel and its derivatives, in particular methyl, 1-hydroxy and tolyl, are suitable according to the invention both chemically pure and technical products, individually or in mixtures.

The corrosion inhibitor of the present invention exhibits very good anti-corrosive activity against corrosion of iron, nickel, copper, aluminum and their alloys, is well soluble and volatile even at lower temperatures. It is preferably applied in the form of an aqueous or alcoholic solution, optionally as an impregnation of the packaging material, in the form of a powder, aerosol or dispersion. The solution and / or dispersion can be applied to the metal products by dipping, dipping and spraying.

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The invention, its effects and uses are further explained in more detail on specific examples of its composition and use.

Table 1 lists five examples of compositions of the mixed inhibitor of the invention.

Inhibitor Components Parts by weight of the components for example

1 2 3 4 5 ammonium benzoate 20 May 15 Dec 10 - 2-aminoethanol benzoate 20 May 15 Dec 20 May 10 40 2,2-iminodiethanol benzoate «* 15 Dec - 20 May - ammonium dimethylphosphite 30 10 - - <· 5 morpholine dimethyl phosphite 25 - - 40 30 piperidine ethyl methyl phosphite - 30 50 40 1,2,3-benzotriazole 1 0.1 - 3 0.5 1-hydroxy-1,2,3-benzotriazole - 0.9 5 2 2

Electrochemical measurement of corrosion system in monitored metals and approximately neutral aqueous medium c (Na _o S0.) =

- 0.01 mol. 1, a high inhibition coefficient was found for all of the exemplified inhibitor compositions. The inhibition coefficient, expressed as the ratio of the mean reduced corrosion rate in the presence of inhibitor to the mean non-reduced corrosion rate in an approximately neutral aqueous environment, ranged from 0.85 to 0 for all the examples of corrosion inhibitor compositions of iron, copper, aluminum and their alloys. , 98.

- 4 Example 1

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A mixture containing 45 parts by weight of 2-aminoethanol benzoate and 35 parts by weight of piperidine dimethylphosphite was dissolved in water to a 3% solution. Into this solution were added samples of steel 11 373 (ČSN 41 1373) for 60 s. After evaporation of solvent, their inhibitory activity until the first corrosion attack was determined according to Annex 02 ČSN 03 8205 / ST SEV 992-78 and results were compared with unprotected samples. Inhibited samples remained free of corrosion products after 10 test cycles, while unprotected samples showed corrosion during the first cycle.

Example 2

A mixture containing 15 parts by weight of morpholine benzoate, 20 parts by weight of morpholine dimethylphosphite and 3 parts by weight of 1,2,3-benzotriazole was dissolved in a 1: 1 water-dimethylketone mixture to an 8% solution. Samples of steel 11 373 and copper 99.85 were immersed in this solution for 120 s. The samples were tested in a similar manner to Example _1.3 and a similar effect was found. Steel samples after 8 cycles and copper samples after 15 cycles were free of corrosion products, while unprotected samples showed corrosion products in steel and local darkening copper already after the first cycle.

Example 3

A mixture of 25 parts by weight of cyclohexylamine benzoate, 35 parts by weight of ammonium methylethylphosphite and 2 parts by weight of a mixture of 1,2,3-benzotriazole and 1-hydroxy-1,2,3-benzotriazole in a 3: 1 weight ratio was dissolved in water to 0.3% - solution. In order to verify the contact effect of the inhibitor, samples of steel 11 373, copper 99.85 (CSN 42 3003) and aluminum 99.5 (CSN 42 4105) were immersed in this solution.

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Whereas samples immersed in the mixed inhibitor solution were found not to be corrosive after 80 days, samples immersed in water without inhibitor were found to be corrosive in steel and copper after cycle 1, in aluminum after 3 · cycle.

Claims (1)

Mixed metal corrosion inhibitor based on a mixture of benzoic acid salts and dialkyl phosphoric acid salts, characterized in that it contains 0.1 to 50 parts by weight of ammonium benzoate, monoethanolamine benzoate, diethanolamine benzoate, triethanolamine benzoate, morpholine benzoate, piperidine benzoate and / or benzoate cyclohexylamine, singly or in admixture, from 0.1 to 80 parts by weight of a dialkylphosphoric acid salt of the formula wherein R ₁ and R 6 are alkyls having a carbon number of up to C 1, preferably methyl and A is ammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, morpholine piperidine and / or cyclohexylamine, singly or in admixture, optionally from 0.001 to 5 parts by weight of 1,2,3-benzotriazole, 1-methyl-1,2,3-benzotriazole, 1-tolyl-1,2,3 -benzotriazole and / or 1-hydroxy-1,2,3-benzotriazole, singly or in admixture.