DE2530562C2 - Use of a concentrated solution of methyl benzotriazole as a corrosion protection agent - Google Patents

Description

Metal surfaces are often exposed to chemical and electrochemical attacks that affect these surfaces destroy. To prevent this corrosion, one can apply methyibenzotriazole on the metal surface build up a monomolecular chelate complex layer that adheres very firmly, is chemically inert, and so on the metal surface removes corrosive influences.

In practice, one usually faces the problem of machine parts that are related to lubricants stand, e.g. bearing shells, against the corrosive Effect of the lubricant (e.g. active sulfur compounds in the lubricating oil). However, this is very difficult because methyl benzotriazole dissolves in Mineral oils in a practically acceptable time only at higher temperatures and then only at low temperatures Amounts.

Some of these difficulties can be avoided by using thiodiazoles as corrosion inhibitors begins. These products are liquid at 20 "C. Let go They mix easily in oil, but are considerably less effective as methylbenzotriazoi.

The object of the invention is to provide a liquid anti-corrosion agent based on methylbenzotriazole, which is easily converted into lubricating oils can be incorporated

U.S. Patent 2,971,912 describes on Column 2, lines 5-21, a synthetic ester oil based lubricant which is an antioxidant in combination with benzotriazole contains. As a further aid, phosphoric acid esters can be added, which the Improve high pressure properties (column 6, lines «5-27). In contrast, the invention relates sought to convert methylbenzotriazoi, which is known to be sparingly soluble, into a form soluble in lubricating oils convict. This is done by the fact that the methyibenzotriazole z. B. a phosphate ester as a solvent is admitted. This inventive solution differs from the cited US patent in that the phosphate esters described there serve a different function.

The FR-PS 15 38 431 describes a dry cleaning S5 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 methyl benzotriazole in the sulfonate as a solvent, which acts as an anti-corrosive 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 solvent for methyl benzotriazole to use it as a corrosion protection agent. 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, methyl benzotriazole is readily soluble in glycols. the Use of a special solvent system to provide a soluble form of methyl benzotriazole there is therefore no need for antifreeze.

DE-AS 12 85 835 describes in column 1, lines 34-41, a corrosion protection agent for metal surfaces, containing, in addition to methyl benzotriazole, an amine salt of a saturated dicarboxylic acid. According to column 2, lines 3-12, the anti-corrosion agent can be water or an organic solvent such as alcohols. Similar to the one already Discussed British patent there is no problem here either, the benzotriazole in a to convert oil-soluble form. The forms of application of the anti-corrosion agent described in column 2, lines 45-52 do not refer to the use of a lubricant based on mineral or synthetic oil, which contains methyl benzotriazole as a corrosion inhibitor.

The invention accordingly relates to the use of a concentrated solution of methyl benzotriazole 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. Thus Methyibenzotriazol is slightly (up to 40%) soluble in the solvents mentioned also at room temperature (20 ⁰ 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 methylbenzotriazot in oil considerably (about nine times). At the same time, the solvent also increases the corrosion-inhibiting effect of the methylbenzotriazole, so that a considerably reduced amount is sufficient for the same effect.

When used according to the invention, the anti-corrosion agent acts particularly against 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 methyl benzotriazole within the meaning 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 6-18 carbon atoms. Particularly preferred

Saturated aliphatic monocarboxylic acids with 6-10 carbon atoms and unsaturated ones are added aliphatic monocarboxylic acids with 6-14 carbon atoms.

The amines on which the salts are based are aliphatic, cycloaliphatic and aromatic Mono-, di- and triamines. Mono-, di- and trialkylamines and their alkyl groups are particularly preferred contain a total of 6-18 carbon atoms.

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

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

2. Amine salts of phosphoric acids

10

15th

20th

30th

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. Here, too, an excess of phosphoric acid is possible.
Salts of alkylamines and phosphonic acids or their mono- or dialkyl esters are particularly preferred. In these salts the total number of carbon atoms in old alkyl groups is preferably 10-40.

Examples of suitable compounds are monobutyl phosphate, di-butyl phosphate, di-2-ethylhexyl phosphate, mono-octadecenyl phosphate
Phosphorsädretrjalkylester, optionally in a mixture with one of the amines mentioned under 1. The molar ratio of phosphoric ester: amine should not exceed 1: 1. Trialkyl phosphorates contain a total of 10-40 carbon atoms in the alkyl groups by preference.
Examples of suitable phosphoric acid esters are tributyl phosphate, tri-2-ethylhexyl phosphate, tridodecyl phosphate / dibutyl-2-ethylhexyl phosphate.
Amine-alkylbenzenesulfonals are preferably salts of the _{amines mentioned under L 1} with alkylbenzenesulfonic acids which have 1-18 carbon atoms in the . _Q contain alkyl group.

Examples are p-toluenesulfonic acid, isooctadecenylbenzenesulfonic acid.

It is possible to use any combination of these solvents.

All these solvents dissolve methylbenzotriazole very concentrated solutions at room temperature. These solutions can also be used without further ado Room temperature into which lubricants are incorporated. In particular, they become mineral lubricating oils added, the corrosive components, e.g. B. contain active sulfur compounds. The im Lubricating oil i. a. a concentration of the methylbenzotriazole from 0.01 to 0.1% by weight to prevent corrosion of copper or copper compounds associated with are in contact with the oil. This concentration is considerably lower than that in the absence of

40

45 solvents required for the same effect. Since liquid corrosion inhibitors are added to the oil, the solvents of which increase the solubility of the methylbenzotriazoles 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 on a paraffinic, naphthenic, arcnatic or mixed basis with the usual viscosities of 2.8-150mm ² / s at 50 ° C, synthetic oils, for example ester oils, alkylbenzenes and their mixtures with mineral oils, lubricating greases, e.g. B. lithium fats, calchim fats.

Examples

Example 1 1) Methylbenzotriazole

400 g of isononanoic acid and 250 g of isododecylamine are mixed in this with stirring and cooling 350 g of methylbenzotriazole are slowly dissolved in the mixture and the solution is filtered. It becomes 35% strength Obtain methylbenzotriazole 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) 30 mg of the solution according to 1),

(C) 10 mg methylbenzotriazole.

The lubricating oils obtained in this way contain:

(A) 0.003 wt% methylbenzotriazole

(B) 0.01 wt% methylbenzotriazole

(C) 0.01 wt% methylbenzotriazo !.

During production, lubricating oils A and B were completely clear after one minute, while in the case of C the additive had not yet dissolved after one hour. In C, the additive did not dissolve until it was heated to 70 ^° C.

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

3) Corrosion test 1.) Cu activity according to ASTM-D-ISO

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 were 0.5% di-tert-nonyl pentasulfide with. 38% total sulfur and 26% active sulfur dissolved.
To 100 ml of this solution were then

a) 30 mg of methylbenzotriazole are ^{stirred in at 90 °} C. in 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, la means no, 4c strong corrosion.

Solution

Cu activity according to ASTM-D-130 130 ° C in

ASTM-D-130, see above, for iron, rust-free, rust spots, surface rust.

3 hours.

5h

solution

a
b
c

3a

Ia-Ib

4c

3a Ib 4c

Corrosion after 48 StcL / 100 ⁰ C
Cu Fe

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

a
b
c

3a / 3b
3a / 3b
4a

Surface grate
Rust spots
Surface grate

98 ml of the oil to be tested are mixed with 2 ml of distilled water in a beaker. Water mixed for 1 min with a stirrer. ^{A steel test specimen, 1} A of the inner ring of an annular groove bearing, and a copper strip, electrolytic copper with dimensions of 50 5 1 mm, are then placed in the beaker without touching the beaker.The beaker is covered with a watch glass and placed in a drying cabinet at 100-2 ° C for 48 hours. After the test time has elapsed, 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 mm ² / s at 50 ° C.

In every 100 g of this oil there was 0.9 g of zinc dialkyldithiophosphate and

a) 30 mg methylbenzotriazole,

b) 30 mg of product from Example 1

stirred in and dissolved and 2 g of water emulsified in. These emulsions were combined with a Sample c) = tested without corrosion protection according to VW-P-1401. The evaluation is carried out for Cu according to Examples 2-29

According to the method of Example 1, the solubility of the were with various solvents Methylbenzotriazole in these solvents, the solubility of the resulting solutions in lubricating oils and the effect of these lubricating oils against the corrosion of copper was tested. The results are shown in Table t. The lubricating oil used was: '.

Example 1-23

28-30 a paraffin-based spindle oil with a viscosity of 6.0 mm ² / s

50 ⁰ C.

Example 24-25 a paraffin-based gear oil with a viscosity of 122.6 mm ² / s at 50 ^° C.

Example 26-27 a naphthenic spindle oil with a viscosity of 8.22 mm ² / s at 50 ° C.

Example 31 Synthetic oil alkylbenzene with a viscosity of 17.2 mm ² / s at 50 "C.

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

Table 1

No solvent 1 Molver Methyl- Solution (4) methyl increase Corrosion ratio benzo- in oil benzo the soluble protective effect triczol triazole speed against for copper ■ f solved in the oil over pure Methylbenzo ; ι 2 triazole around % % % factor 3 4th 5 6th 7th t

Octadecyl phosphate

Di-2-ethylhexyl phosphate

Tri-2-ethylhexyl phosphate

Tri-n-butylphphosphate

p-toluenesulfonic acid + i-tetradecylamine

i-Octadecenylbenzenesulfunic acid + t-Octy ¹ amine

35

0.4

0.14

7.0

1: 1

1: 1

35 0.4 0.14 7.0 25th 0.4 0.1 5.0 35 0.4 0.14 7.0 40 0.15 0.06 3.0

25th

0.2

0.05

2.5

8th solvent 7th Molver 25th 30 562 Melhyl 8th hiillnis gasoline Iru / ol Increase in corrosiveness 9 Melliyl Solution (4) in the oil (icr solubility protection effect continuation benzo- in oil wedge for Kupier No. In.i / ol over pure 10 solved % Mclhylbcnzo- .1 (ι Iriiizol around 11th n-caproic acid I: 0.5 0.12 factor + Dicyclohexyl- % % 7 H. 12th amine I. V 6.0 + n-lauric acid 1: 0.5 40 0.3 0.14 ι 13th + Dicyclohexyl- amine 7.0 + Caproic acid 1: 0.5 40 0.35 0.10 14th + t-knoctylamine Lauric acid 1: 0.5 0.09 5.0 + + t-iso-octylamine 40 0.25 15th Caproic acid 1: 0.5 0.1225 4.5 + + n-hexylamine 30th 0.3 Valerionic acid 1: 0.5 0.08 6,125+ 16 + tert-isotetra- 35 0.35 decylamine 4.0 + Caproic acid 1: 0.5 40 0.2 /7.14 17th + tert-iso-tetra- decylamine 7.0 + Lauric acid 1: 0.5 40 0.35 0.105 18th + tert-iso-tetra- decylamine 5.25 + Isononanoic acid 1: 0.5 30th 0.35 0.1225 + tert-iso-tetra- decylamine 6.125 + 19th Isononanoic acid 1: 1 35 0.35 0.105 + t-iso-tetra- decylamine 5.25 + 20th mono-n-butyl 0.3: 0.3: 0.4 30th 0.35 0.12 phosphate + di- n-butyl phosphate 6.0 + 21 + tert-iso-tetra- 40 0.3 decylamine Tributyl phosphate 0.9: 0.1 0.18 22nd + tert-iso-tetra- decylamine 9.0 + Tributyl phosphate 0.9: 0.1 30th 0.6 0.04 23 + tert-iso-tetra- decylamine 2.0 Tributyl phosphate 0.7: 0.3 40 0.1 0.195 24 + tert-iso-tetra- decylamine 9.75 + Tributyl phosphate 0.7: 03 30th 0.65 0.14 25th + tert-iso-tetra- decylamine 7.0 + Tributyl phosphate 0.7: 0.3 40 035 0.1 + tert-iso-tetra- decylamine 5.0 + Tributyl phosphate 0.7: 03 50 04 0.18 + terL-iso-tetra- decylamine 9.0 + Tributyl phosphate 0.7: 0.3 30th 0.6 0.16 + terL-iso-tetra- decylamine 8.0 + 40 0.4

solvent 9 Molver 25th 30 562 Methyl- 10 ratio benzo- triazole Increase in corrosion Methyl- Solution (4) in the oil the solubility school effect Korlscl / ung benzo- in oil for copper No. triazole over pure solved % Methylbenzo- \ 2 3 6th triazole around Tributyl phosphate 0.7: 0.3 0.15 Factor :.) + tert-iso-tetra- % % 7 S Ϊ. decylamine 4th 5 7.5 + iij Tributyl phosphate 0.7: 0.3 30th 0.5 0.10 ι + tert-iso-tetra- Ά 26th decylamine 5.0 +} Tributyl phosphate 70:30 40 0.25 0.135 + isüfiüriänsaurcri 27 Tributyl phosphate 0.1: 0.3: 0.6 0.135 6.75 + + tert-iso-tetra- 30th 0.45 decylamine 6.75 + 28 + Isononanoic acid 30th 0.45 Tributyl phosphate 0.3: 0.25: 0.45 0.105 29 + tert-iso-tetra- decylamine 5.25 + + Isononanoic acid 30th 0.35 Tributyl phosphate 0.7: 0.3 0.18 30th + tert-iso-tetra- decylamine 9.0 + i Tributyl phosphate 0.7: 0.3 40 0.45 + tert-iso-tetra- * 40% 31 decylamine 20 + 40 in each Relationship - 32 miscible

Claims (1)

Patent claim: Use of a concentrated solution of methyl benzotriazole m an amine salt of a carboxylic acid, an amine salt of a phosphoric acid, a phosphoric acid alkyl ester, an amine alkyl benzene sulfonate or their mixtures as corrosion protection agents in lubricating oils. 10