DE2429512C2 - Use of a concentrated solution of benzotriazole and / or tetrahydrobenzotriazole as a corrosion protection agent - Google Patents

Description

Metal surfaces are often chemical and electrochemical Exposed to attacks that destroy these surfaces. To prevent this corrosion, you can use benzotriazole or tetrahydrobenzotriazole on the metal surface to create a monomolecular Build up a chelate complex layer, which adheres very firmly and is chemically inert, and thus the metal surface removes corrosive influences.

In practice, one usually faces the problem of machine parts that are related to lubricants stenen, z. B. bearing shells, against the corrosive effect of the lubricant (e.g. active sulfur compounds in the lubricating oil). You then have to dissolve the benzotriazole in the lubricant. This works but only with great difficulty, because benzotriazole does not dissolve in mineral oils until .so higher temperatures and then only in small quantities. Tetrahydrobenzotriazole also has one corrosion-inhibiting effect, is somewhat more soluble, but here too it is dissolving and mixing in an oil extremely difficult and time consuming.

Some of these difficulties can be avoided by using thiodizoles as corrosion inhibitors. These products are ^{liquid at 20 °} C., can easily be mixed into oil, but are considerably less effective than benzotriazole. -to

The object of the invention is to provide a liquid anti-corrosion agent to provide on a benzotriazole basis available, which can be easily incorporated into lubricating oils.

U.S. Patent 2,971,912 describes a synthetic lubricant at column 2, lines 5-21 Base ester oil, which contains an antioxidant in combination with benzotriazole. As a further aid Phosphoric acid esters can be added to improve the extreme pressure properties (column 6, lines 5 - 27). In contrast, the invention relates to benzotriazole, which is known to be sparingly soluble is to be converted into a form soluble in lubricating oils. This is done dadus ch that the benzotriazole z. B. a Phosphate ester is added as a solvent. This inventive solution is different from that cited US patent in that the phosphate esters described there have a different function to serve.

The FR-PS 15.38 431 describes a dry cleaning agent, consisting of benzotriazole, a detergent and a solvent. As a solvent for example, on the left-hand side, second paragraph on page 2, chlorine-containing hydrocarbons listed. Amine alkylbenzenesulfonates, for example, can be added as detergents. As in the 3rd Described in the first paragraph of the left column on page 2, these sulfonates cause severe corrosion of the Metal surface when used in combination with a solvent. The present invention in contrast, concerns z. B. a solution of benzotriasol in the sulfonate as a solvent, which acts as an anti-corrosion agent in lubricating oil If now, as the French patent teaches, that Sulphonate has a highly corrosive effect, one of ordinary skill in the art will not consider this compound Use benzotriazole solvent to prevent corrosion. This professional takes from the French patent that the sulfonate compounds are highly corrosive and thus, as a solvent for a corrosion inhibitor, it cannot be considered.

GB-PS 811675 mentions benzotriazole as Corrosion inhibitor in antifreeze based on ethylene glycol. As on page 1, right column in the first Paragraph described, avoids the addition of cyclohexylamine a rise in pH during of use. As the person skilled in the art is familiar with, benzotriazole is readily soluble in glycols. Using a special solvent system to provide a soluble form of benzotriazole on the Antifreeze area is therefore unnecessary.

DE-AS 12 85 835 describes column 1, lines 34-41, a corrosion protection agent for metal surfaces, containing, in addition to benzotriazole, an amine salt of a saturated dicarboxylic acid. The anti-corrosion agent can according to column 2, lines 3 - 12, water or a organic solvents, such as alcohols, contain. Similar to the British patent, which has already been discussed, this does not apply here either Problem of converting benzotriazole into an oil-soluble form. Those described on column 2, lines 45-52 Application forms of the corrosion protection agent do not relate to the use of a lubricant based on mineral or synthetic oil, which contains benzotriazole as a corrosion inhibitor.

The invention accordingly relates to the use of a concentrated solution of benzotriazole and / or tetrahydrobenzotriazole in an amine salt of a carboxylic acid, an amine salt of a phosphoric acid, a phosphoric acid trialkyl ester, an amine alkylbenzenesulfonate or mixtures thereof as a corrosion protection agent in lubricating oils.

These solutions have a number of unexpected advantages. Benzotriazole or tetrahydrobenzotriazole is easily (up to 40%) soluble in the solvents mentioned, even at room temperature (20 ^{° C.).} The solutions are liquid. They can be incorporated into lubricants at room temperature. Here, too, the solvent acts as a solubilizer and increases the solubility of the benzotriazole or tetrahydrobenzotriazole in oil considerably (about nine times). At the same time, the solvent also increases the corrosion-inhibiting effect of the benzotriazole, so that a considerably reduced amount is sufficient for the same effect.

The anti-corrosion agent of the invention is particularly effective against the corrosion of non-ferrous metals, such as Copper and copper alloys, through sulfur compounds such as active sulfur-containing lubricating oil additives. Therefore it is preferred for this purpose.

Solvents for benzotriazole or tetrahydrobenzotriazole in the context of the invention are:
1. Amine salts of carboxylic acids

The carboxylic acids on which the salts are based are, in particular, aliphatic monocarboxylic acids

with € -18 carbon atoms. Particularly preferred are saturated aliphatic monocarboxylic acids with 6-10 carbon atoms and unsaturated aliphatic monocarboxylic acids having 6-14 carbon atoms. The amines on which the salts are based are aliphatic, cycloaliphatic and aromatic mono-, di- and triamines. Particularly preferred are mono-, di- and trialkylamines, the alkyl groups of which contain a total of 6-18 carbon atoms.

In addition to these salts, an excess of the acid can also be present, the molar ratio of amine to acid preferably not exceeding 1: 1.
Examples of suitable carboxylic acids are caproic acid, capric acid, isononanoic acid, isopemitipic acid and oleic acid.

Examples of suitable amines are n-hexylamine, teit-octylamine, tert-isotetradecylamine, oleylamine, Dicyclohexylamine, aniline.

2. Amine salts of phosphoric acids

The same amines that are used to form the carboxylic acid salts are suitable here. Phosphoric acids are phosphoric acid itself or its mono- and dialkyl esters. A neutral salt is preferably formed from these phosphoric acids, ie all acidic hydrogen atoms present are converted. An excess of phosphoric acid is also possible here.
Salts of alkylamines and phosphoric acids or their mono- or dialkyl esters are particularly preferred. In these salts, the total number of carbon atoms in all alkyl groups is preferably 10-40.

Examples of suitable compounds are mono- J> butyl phosphate, di-butyl phosphate, di-2-ethylhexyl phosphate, mono-octadeceny] phosphate.

3. Trialkyl phosphoric acid, optionally mixed with one of the amines mentioned under 1.. That The molar ratio of phosphoric acid ester to amine should not exceed 1: 1. Phosphoric acid trialkyl ester preferably contain a total of 10-40 carbon atoms in the alkyl groups.

Examples of suitable phosphoric acid esters are tributyl phosphate, tri-2-ethylhexyl phosphate, tridodecyl phosphate, Dibutyl 2-ethyl hexyl phosphate.

4. Amine-alkylbenzenesulfonates are preferably salts of the amines mentioned under 1. with alkylbenzenesulfonic acids which have 1-18 carbon atoms in the Contain alkyl group. Examples are p-toluenesulfonic acid, isooctadecenylbenzenesulfonic acid.

It is possible to use any combination of these solvents.

All of these solvents dissolve benzotriazole and tetrahydrobenzotriazole into very concentrated solutions at room temperature. These solutions can also be readily incorporated into the lubricant at room temperature. In particular, they are added to mineral lubricating oils which corrode bo Rende ingredients z. B. contain active sulfur compounds. A concentration of the benzotriazole or tetrahydrobenzotriazole of 0.01 to 0.1% by weight in the lubricating oil is generally sufficient to prevent the corrosion of copper or copper compounds which are in contact with the oil. This concentration is considerably lower than that required for the same effect in the absence of the solvent. Since liquid corrosion inhibitors are added to the oil, the solvents of which increase the solubility of the benzotriazoles or tetrahydrobenzotriazoles in the oil, there is also no risk of separation.

In principle, any lubricant can be given a corrosion-inhibiting finish in this way.

Examples of particularly suitable lubricants are mineral oils of paraffinic, naphthenic, aromatic or mixed base with standard viscosities of 2,8-150mm ² / s at 50 ⁰ C, synthetic oils, for example Esteröle, alkylbenzenes and mixtures thereof with mineral oils, lubricating greases, eg. B. lithium fats, calcium fats.

Examples

example 1
1) Benzo triazole solution

400 g of isconanoic acid and 250 g of isododecylamine are mixed with stirring and cooling. In this Mixture, 350 g of benzotriazole are slowly dissolved and the solution is filtered. It gets a 35% Obtain benzene triazole solution.

2) solubility in mineral oil

In each 100 g of paraffin-based spindle oil are stirred at 22 ° C:

(A) 10 mg of the solution according to 1),

(B) 36 mg of the solution according to 1),

(C) 10 mg benzotriazole,

(D) 10 mg tetrahydrobenzotriazole,

(E) 10 mg thiadiazole.

The lubricating oils obtained in this way contain:

(A) 0.003 wt% benzotriazole

(B) 0.01 wt% benzotriazole

(C) 0.01 wt% benzotriazole

(D) 0.01 wt% tetrahydrobenzotriazole

(E) 0.01 wt% thiadiazole.

During production, lubricating oils A, B and E were completely clear after one minute, while for C and D the additive had not yet dissolved after one hour. In C, the addition solved only at heating at 70 ° C in D when heated to 50 ⁰ C.

In the same lubricating oil, 0.02% by weight of benzotriazole dissolved at 22 ° C., but 0.3% (corresponding to 0.1 % By weight benzotriazole) of the solution according to 1).

3) Corrosion test

1. Cu activity according to ASTM-D-130

The test was carried out in a commercially available paraffinic mineral oil with a viscosity of 6.0 mm ² / s at 50 ^° C.

In this oil, 0.5% thiononylphenyl polysulfide with 38% total sulfur and 26% active sulfur was dissolved.
To 100 ml of this solution were then

a) 30 mg of benzotriazole are ^{stirred in at 90 °} C. in the course of half an hour;

b) 30 mg of product from Example 1 are ^{stirred in at 25 °} C. in 10 minutes.

These solutions were then used together with a sample c) = without the addition of corrosion inhibitors tested in accordance with ASTM-D-130 in the Cu strip test. Here 1 a means no corrosion, 4c means severe corrosion.

solution

Cu activity tested in accordance with ASTM-D-130 at 130 C in VW-P-1401. The assessment is carried out for Cu in accordance with ASTM-D-130, see above, for iron, rust-free, rust spots, surface rust

3 hours.

5h

solution

Corrosion after 48h / 100 ° C "

a 3a b Ia-Ib C. 4c

3a
Ib Cu

Fe

2. V-W ring groove test according to VW-P-1401

In a beaker, 98 ml of the oil to be tested are mixed with 2 ml of distilled water for 1 min using a stirrer. A test specimen made of steel '/' of the inner ring of a ring groove bearing and a copper strip, electrolytic copper with the dimensions 50 5 1 mm, are then placed in the beaker without touching the beaker. at 100-2 ⁰ C in a drying cabinet. After the test period has expired, the test specimens are removed. The assessment is carried out for copper according to ASTM-D-130, for iron, rust-free, rust spots, surface rust.

The test was carried out again in a commercially available paraffinic mineral oil with a viscosity of 6.0 nm ² / s at 50 ° C.

In every 100 g of this oil were 0.9 g of zinc dialkyldithiophosphate and

a) 30 mg benzotriazole,

b) 30 mg of product from Example 1

stirred in and dissolved and emulsified in 2 g of water. These emulsions were used together with a Sample c) = without corrosion protection according to

Table 1

3b
3b
4a

Examples 2-29

Surface grate Rust spots Surface grate

According to the method of Example 1, the solubility of the were with various solvents Benzotriazole in these solvents, the solubility of the resulting solutions in lubricating oils and the The effectiveness of these lubricating oils against the corrosion of copper has been tested. Table 1 shows the results.

The lubricating oil used was:

Example 1 - 23, 28 - 30 a paraffin-based spin

del oil with a viscosity of 6.0 mm ² / s at 50 ° C. Example 24-25 with a paraffin-based gear oil

a viscosity of 122.6 mm ² / s at 50 ° C. Examples 26-27 with a naphthenic spindle oil

a viscosity of 8.22 mmVs at 50 ° C. Example 31 Synthetic oil alkylbenzene with a viscosity

of 17.2mm ² / s at 50 ° C.
Example 32 Synthetic oil, commercially available ester oil based on sebacic acid with a viscosity of 12.1 mnvV at 50 ° C.

1 1 3 4 ' 5 ό 7th 8th No. solvent Communication Benzo- solution Bcnzo- Increase in Corrosion triazole (4) in oil Iriazol solubility protection solved % in the oil opposite to effect % % pure benzo- for copper triazole around factor

2 Octadecylphosphhal 3 Di-2-ethylhexyl phosphate 4th Tri-2-ethylhexyl phosphate 5 Tri-n-butyl phosphate 6th p-toluenesulfonic acid + i-tetradecylamine 7th i-octadecenylbenzenesulfone acid + t-octylamine 8th n-caproic acid + dicyclo- hexylamine 9 n-lauric acid + dicyclo- hexylamine 10 Caproic acid + t-isooctyl- amine Il Lauric acid + t-iso- oclylamine 12th Caproic acid + n-hexyl- amine 13th Valerionic acid + tert-iso- tel.radecylamine

1: 1

1: 1

: 0.5

1: 0.5

1: 0.5

1: 0.5

1 0.5

1: 0.5

35 0.3 35 0.3 25th 0.35 35 0.3 40 0.1 25th 0.15 40 0.25 40 0.3 40 0.2 30th 0.2 35 0.3 40 0.15

0.105
0.105
0.088
0.105
0.04

0.037

0.1

0.12

0.08

0.06

0.105

0.06

5.25

5.25

4.4

5.25

2.0

1.87

5.25

continuation

ι 2 3 4th 5 6th 7th 8th No. solvent Molveiiillnis iBenzw- SOLUTION increase of the Corrosive 'triuKO'l (4) in OH triawri solubility schtiu- dissolved ¹¹ A in the oil opposite to mentoring X pure Bennv for Kupier Ιΐύζοί around lalilor

Caproic acid + tetradecylamine

Lauric acid + icrt-4 «otetradecyiamine

Isononansauire + ten_-lsotetradecyUmin

Isononanoic acid c + t-isoteadecylamine

mono-n-butyl-phosphorus + Di-n-Butylphosphzt + terL-iso-tetiadecylamine

Tributyl phosphate + lert.-I so-tctradecylamine

Tributyl phosphate + terL-I so-tetradecylamine

Tributyl phosphate + terL- ! so-tetradecylamine

Tributyl phosphate + tert-iso-tetradecylamine

Tributyl phosphate + tert.-! so-tetradecylamine

Tributyl phosphate + tert-iso-tetradecylamine

Tributyl phosphate + tert_- 1 so-tetradecylani in

Tributyl phosphate + tert-iso-tetradecylamine

Tributyl phosphate + tert-iso-teiradecylamine

Tributyl phosphate + isononanoic acids

Tributyl phosphate + tert-iso-tetradecylamine + Isononanoic acid

Tributyl phosphate + tert, -iso-tetradecylamine + Isononanoic acid

Iso-tetradecylamine

Tributyl phosphate + tert-iso-tetradecylamine

1: 0.5 40 1: «_ 5 30th 1: 0.5 35 I: 1 30th 0 3: 03: 0.4 40 0.9.0.1 30th 0.9: 0.1 40 0.7: 0.3 30th 0.7: 0.3 40 0.7: 0.3 50 0.7: 0.3 30th 0.7: 0.3 40 0.7: 0.3 30th 0.7: 0.3 40 0.70: 0.30 30th 0.1: 0.3: 0.6 30th

0.3: 0.25: 0.45 8.3 0.3 OJ OJ 0.2

0.5

0.6

0.15

0.25

0.12

0.09

0.JO5

0.09

0.08

0.15

6 4.5

5.25

4.5

7.5

0.18 9 0.12 6th 0.075 4th 0.24 5 0.16 3 0.15 3 0.10 2 0.12 6th 0.12 6th

0.09

0.7:

0.4 O.! 6

in each -40%> 20

relationship

miscible

Claims (1)

Claim: Use of a concentrated solution of benzotriazole and / or tetrahydrobenzotriazole in an amine salt of a carboxylic acid, an amine salt of a phosphoric acid, a phosphoric acid trialkyl ester, an amine alkylbenzenesulfonate or mixtures thereof as a corrosion protection agent in lubricating oils.