CS226342B1 - Iron and iron alloy corrosion inhibiting composition - Google Patents

Description

The present invention relates to a mixed evaporative corrosion inhibitor of iron and its alloys in approximately neutral aqueous environments, particularly atmospheric conditions.

The influence of atmospheric corrosion on iron and its alloys products is considerably unfavorable, as corrosion products are formed which degrade them both functionally and visually.

In order to reduce or eliminate these negative phenomena, a number of temporary protection methods and means are used in products, of which the use of evaporation inhibitors is of great importance, especially during transport and storage.

Most of the known scavenging inhibitors are characterized by high inhibitory activity, but are used on an industrial scale for their hygienic defectiveness. These include nitric acid anionic vapor inhibitors, in particular dicyclohexylamine nitrite and diisopropylamine nitrite.

Octadecylamine is particularly known from the non-toxic evaporation inhibitors,

1,2,3-benzotriazole and its alkyl derivatives, ammonium benzoate and a number of other mixed evaporation inhibitors, which, however, are characterized by low volatility, especially at low temperatures and at low temperatures. in the absence of moisture, and in some cases poor solubility.

The disadvantages of the prior art in this field are largely overcome by the mixed evaporative corrosion inhibitor of iron and its benzoic acid alloys according to the invention, characterized in that the inhibitor contains from 90 to 99.9 wt. % of benzoic acid salts of alkoholamines, singly or in admixture, e from 0.1 to 10 wt. % alkyl esters of benzoic acid having 2 to 4 carbon atoms in the alkyl, for example the ethyl ester. As benzoic acid salt, 2-aminoethanol benzoate HgN-CHgCHg-COOCgH 3, 2,2'-lmino-dietenol benzoate is used.

HN 'CHgCH

-CHgCH

2 '

COOC ₆ H ₅

COOCgH ₅ and optionally benzoate 2,2 ', 2''- nitrilotriethanol

CH ₂ CH ₂ -COOC ₆ H ₅ N CH ₂ CH ₂ -COOC ₆ H ₅ CH ₂ CH ₂ -COOC ₆ H ₅ .

It is also an object of the invention to find an optimal inhibitor concentration in a solvent for solution application. In this case, the inhibitor contains 0.01 to 50 wt. % and preferably 0.5 to 10 wt. % of active ingredients 50 to 99.9 wt. % of a solvent such as water or ethanol. Using this concentration, an inhibitor layer of 0.1 to 5 g / m ^@ 2 is formed on the treated surface after evaporation of the solvent.

The corrosion inhibitor of the present invention exhibits very good corrosion inhibitory activity against iron and its alloys, is hygienically harmless, well soluble and volatile even at low temperatures.

It is preferably applied in the form of an aqueous or alcoholic solution or a solution. as impregnation of the packaging material, in the form of a powder or an aerosol. The solution can be applied to the products by dipping, immersion or spraying.

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 wt. % folders example AND (B) C D E 2-eminoethanol benzoate 99 - 20 May 2,2'-iminodiethanol benzoate 45 90 30 2,2 ', 2-nitrilotriethanol benzoate 50 40 98 ethyl benzoate 1 5 2 propyl benzoate 10 5 Butyl ester of benzoic acid - 5 - - -

Electrochemical measurements of the corrosion system of the metal of interest and the approximately neutral aqueous medium - 0.01 N sodium sulphate solution - revealed an inhibition coefficient for all of the inhibitor compositions shown. The coefficient of inhibition, which is expressed as the ratio of the mean reduced rate of corrosion in the presence of inhibitor to the mean non-reduced rate of corrosion in an approximately neutral aqueous medium for steel grades. 11 - according to ČSN 41 1373 - for all mentioned examples the composition of the inhibitor ranged from 0.92 to 0.95.

He did

Mixture containing 99 wt. % 2-eminoethanol benzoate and 1 wt. % ethyl benzoate was dissolved in water to a 5% solution. Samples of steel, 1,378 for 20 to 60 s, were introduced into this solution. After evaporation of the solvent, the basis weight of the inhibitor was determined to be 0.3 to 1.2 g.m. The samples were then tested according to Annex 02 ČSN 03 8205 / ST SEV 992-78 and the results were compared with unprotected samples. The inhibited samples remained free of corrosion products after 9 test cycles, while unprotected samples showed rust formation as early as the first cycle.

Example 2

A mixture of 45 g of 2,2'-iminodiethanol benzoate, 50 g of benzoate, 2,2 ', 2-nitriloethanol and 5 g of butyl benzoate was dissolved in ethanol to a 5% solution. Samples of steel 11 378 were immersed in this solution for 20 to 60 s. After evaporation of the solvent, the basis weight of the inhibitor was determined to be 0.7 to 1.5 g.m. The samples were then tested in the same manner as Example 1 and a similar effect was found; after 6 test cycles, the samples were free of corrosion products.

Example 3

90 wt. % benzoate, 2,2-iminodiethanol and 10 wt. % of benzoic acid propyl ester was sprayed by spraying with a 40 ° C hot air jet onto samples of 11 373 steel located in a room temperature space. After 5 min. by aerosolization, the basis weight of the inhibitor was found to be in the range of 0.5 to 1.8 g.m. In a test similar to the previous examples, rust was not found after 9 test cycles.

Example 4

Mixed inhibitor of 98 wt. 2,2 ', 2-nitrilotriethanol and 2 wt.% ethyl benzoate were dissolved in ethyl alcohol to a solution containing about 50 wt. % inhibitor. The wrapping paper was impregnated with this solution. After evaporation of the solvent to ensure a basis weight of inhibitor in the packaging paper 20 gm ^- ^. During the test according to ČSN 03 8205 / ST SEV 992-78, the first formation of 11 373 carbon steel was found after more than 9 cycles.

The inhibitor of the invention can be used to protect all ferrous products from corrosion in all of the above uses.

Claims (5)

A mixed evaporative corrosion inhibitor of iron and its alloys based on salts of benzoic acid, characterized in that it contains from 90 to 99.9% by weight of the composition. % of salts of benzoic acid with alcoholamines individually or in a mixture and from 0.1 to 10 wt. % alkyl esters of benzoic acid having 2 to 4 carbon atoms in the alkyl, for example the ethyl ester. 2. A mixed evaporation inhibitor according to claim 1, wherein the benzoic acid salt is 2-aminoethanol benzoate HgN-CH3CHg-COOCgH3. 3. The mixed evaporation inhibitor according to item 1, optionally. 2. The method of claim 2 wherein the benzoic acid salt is 2,2'-iminodiethanol benzoate. HN ch ₂ ch ₂ -cooc ₆ h ₅ ch ₂ ch ₂ -cooc ₆ h ₅ 4. The mixed evaporation inhibitor according to item 1, respectively. 2 and 3, characterized in that 2,2 ', 2-nitrilotriethanol benzoate is used as the benzoic acid salt. -CH ₂ CH ₂ -COOC ₆ H ₅ -CH ₂ CH ₂ -C00C ₆ H ₅ CH ₂ CH ₂ -COOC ₆ H ₅ 5. An inhibitor according to any one of Claims 1 to 4, characterized in that from 0.01 to 50 wt. %, Preferably to 0.5 to 10 wt. The active ingredients comprise 99.9 to 50 wt. % of a solvent such as water or ethanol.