DE1263210B - High temperature lubricating oils - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

ClOm

German KL: 23 c -1/01

Number: 1263 210

File number: D 46654IV c / 23 c

Filing date: March 2, 1965

Opening day: March 14, 1968

Many lubricants, for example those based on mineral oil, are indeed ^{satisfactory at temperatures of 100 to 150 °} C., but at 200 ^° C. they form considerable amounts of sludge and acid; in addition, their viscosity increases at this temperature.

It was found that the esters of polyhydric alcohols having at least two methylol groups bonded to a quaternary carbon atom, such as 1,2,2-trimethylolpropane and alkanecarboxylic acids, are most suitable as lubricants for jet engines. Although these compounds have a relatively high oxidation and thermal stability, they are not sufficiently resistant to the motors when the bottom temperatures of 170 ⁰ C and the storage temperatures exceed 315 ⁰ C.

The aim of the present invention is therefore to improve the oxidation and heat resistance of high-temperature lubricating oils, the z. B. be used in jet aircraft, especially those based on of carboxylic acid esters of polyhydric alcohols, and make them resistant to resin formation close.

The high-temperature lubricating oils according to the invention based on organic carboxylic acid esters, the optionally contain known organic amines, are by a content of 0.1 to 5 percent by weight a compound of the general formula

R, N

characterized in which R is alkyl radicals with 1 to 10 carbon atoms, R 'is hydrogen, alkyl radicals with 1 to 10 carbon atoms, phenyl, vinyl or alkoxy radicals with 1 to 4 carbon atoms and η is 1, 2 or 3, however, at least one of the radicals R 'is hydrogen, a vinyl or an alkoxy radical having 1 to 4 carbon atoms.

The preferred quantity range of the additive according to the invention is 0.5 to 3%, based on the weight of the lubricating oil. In general, the addition of more than 2% anti-oxidant high temperature lubricating oils

Applicant:

Dow Corning Corporation, Midland, Mich.
(V. St. A.)

Representative:

Dr. B. Passport, lawyer,

8000 Munich 22, Von-der-Tann-Str. 14th

Named as inventor:

Harry M. Slate,

Donald R. Weyenberg, Midland, Mich. (V. St. A.)

Claimed priority:

V. St. v. America March 9, 1964 (350 543)

the agent achieved only a slight improvement in the lubricating oil.

Examples of alkyl radicals R and R 'are methyl, ethyl and tert-butyl, propyl, octyl and decyl radicals. Examples of alkoxy radicals R 'are methoxy, ethoxy, propoxy, butoxy or isopropoxy radicals. Since at least one of the radicals R 'is a hydrogen atom, vinyl or alkoxy radical, phenyl radicals are preferred as the remaining radicals R'. As radicals R, ethyl radicals are preferred. Since η is an integer from 1 to 3, there can be 1 to 3 dialkylaminophenyl radicals per molecule of the organosilicon compounds used as antioxidants according to the invention. However, compounds with 1 or 2 dialkylaminophenyl radicals are preferred.

The antioxidants used according to the invention can be produced, for example, by that first the corresponding p-halogen-N, N-dialkylaniline with magnesium according to Grignard or reacted with lithium and then the organometallic compounds thus obtained with the corresponding Chlorosilane according to the equation

AX

(R, R 'and η have the abovementioned Be 50 Both the production of the organometallic definition, A is MgX, where X is any halogen bond, as well as their reaction with the chlorine atom, or lithium) are implemented. silanes, is conveniently used in tetrahydrofuran as

809 518/618

Solvent carried out. The formation of the organometallic compounds takes place advantageously at Temperatures a little above room temperature, the implementation of the organometallic compounds with the chlorosilanes is preferably carried out in such a way that the mixture is heated under reflux for a prolonged period. The product can then be separated from the metal salts.

The antioxidants according to the invention also show their antioxidative properties and their Stabilizing effect with regard to viscosity and acid formation in the high-temperature lubricating oils Based on alkanecarboxylic acid esters still have the unexpected advantage that they promote resin formation in such High temperature lubricating oils prevent, in contrast to such antioxidants, which save Dialkylaminophenyl radicals only Si-bonded alkyl radicals and those according to US Pat. No. 2,779,738 for the prevention of oxidation can be used in mineral oils. The superior effect of the invention Antioxidants can be clearly seen from the test report attached to Example 2.

The organosilicon compounds used according to the invention to prevent oxidation are suitable for the stabilization of all organic high-temperature lubricating oils. Particularly beneficial however, in the case of esters from polyhydric alcohols with at least two to one quaternary C-atom bonded methylol residues and alkanecarboxylic acids. The alkanecarboxylic acids each advantageously contain at least 5 carbon atoms, preferably 5 to 8 carbon atoms. They are preferably straight-chain, such as n-pentane, η-hexane, n-heptane and n-Octanecarboxylic acid, but they can also be branched, such as 2,3-dimethylpentanecarboxylic acid. the Polyhydric alcohols can also be esterified with a mixture of different alkanecarboxylic acids be.

The polyhydric alcohols or polyalcohols can have up to four methylol groups on one contain quaternary carbon atoms. The term "quaternary carbon atom" denotes 1 carbon atom, the one on four other carbon atoms are bonded directly, so that the carbon atom is in the ^ position to the hydroxyl groups of the Methylol groups are not bound to any hydrogen atom. Esters of such alcohols have a higher resistance to oxidation as esters of alcohols which have a hydrogen atom on the C atom in the ^ position for Have hydroxyl group. Examples of polyhydric alcohols of the type described are also already mentioned 1,2-, 2-trimethylolpropane, 1,1,1-trimethylolethane, Neopentyl glycol, 2 - butyl - 2 - ethyl-1,3-propanediol and 2,2,4-trimethyl-1,3-pentanediol. The preferred ester is the tri-n-heptanoate of trimethylolpropane.

The esters can be obtained by reacting the polyhydric alcohol with a slight excess of alkanecarboxylic acid. This reaction is expediently carried out in the presence of customary esterification catalysts, such as p-toluenesulfonic acid, benzenesulfonic acid, zinc and / or lead salts, at 180 to 240 ^° C. over a period of 6 to 14 hours. The water formed is, preferably with the use of an azeotropic substance such. B. a liquid.Kohlenwasserstoff, evaporated.

Another example of high temperature lubricating oils are the esters of tertiary alkyl carbinols and dicarboxylic acids. These carbinols have a methylol radical on a quaternary carbon atom and preferably likewise no hydrogen atoms on C atoms in / J-position to the hydroxyl group. The carbinols preferably contain. 5 to 12 carbon atoms each. Examples of such carbinols are 2,2,4-trimethyl-1-pentanol and 1-methylcyclohexyI-methanol. The dicarboxylic acids preferably each contain 4 to 12 carbon atoms. Examples of such Dicarboxylic acids are glutaric, adipic, suberic and sebacic acids. Sebacic and adipic acids are preferred. Examples of corresponding esters are bis (2,2,4-trimethylpentyl) sebacate and bis (1-methylcyclohexylmethyl) sebacate and bis (1-methylcyclohexylmethyl) adipate. Processes for the production of these esters are described in "High-temperature Lubricating Fluids" by Blake, Edwards, Hammann, and Reichard in Wright Air Development Command TR 54-532 Pt. 2 (January 1956).

The organosilicon compounds used according to the invention can also be used to increase the Oxidation and heat resistance of mixtures of different lubricating oils, e.g. B. Mixtures of Silicone lubricating oil and the esters described above can be used.

It has also been found that mixtures of dialkylaminophenylsilanes used according to the invention and organic amines known as antioxidants in high-temperature lubricating oils prevent an increase in viscosity and acid formation better than the respective compounds alone, even if the compounds are used in equivalent amounts. Also in connection with such mixtures, the esters of polyhydric alcohols are preferred as high temperature lubricating oils. Examples of organic amines known as antioxidants which can be used in conjunction with the antioxidant organosilicon compounds described above are: phenyl-a-naphthylamine, phenothiazine, phenyl- β- naphthylamine, N-ethyl-1-naphthylamine, 1-naphthylamine and dioctyldiphenylamine . So z. B. the heat and oxidation resistance of the triheptanoate of 1,2,2-trimethylolpropane especially by adding 0.5% phenothiazine and 0.5% (p-diethylamino) -diphenylsilane or of 0.5% N-ethyl-1- naphthylamine and 0.5% (p-diethylamino) -methyldimethoxysilane or of 1.5% 1-naphthylamine and 0.5% (p-diethylaminophenyl) -diphenylvinylsilane or of 1.0% dioctyldiphenylamine _c and 1.0% bis- ( p-Dipropylaminophenyl) -phenylpropoxysilan, in each case based on the weight of the lubricating oil, increased.

A preferred purely organic amine to be used is phenyl-a-naphthylamine. The synergistic The effect of these antioxidant mixtures is likely to be due to the complementary properties of their constituents are based. While the organosilicon compounds appear mainly at very high temperatures The purely organic amines in particular are likely to develop their anti-oxidation effect act at low temperatures. Also the mixtures of antioxidative organosilicon compounds and amines known as antioxidants are used in amounts of 0.1 to 5%, preferably 0.5 to 3%, each based on the weight of the lubricating oil, is used. The antioxidant mixes consist preferably of 20 to 80%, in particular 35 to 65%, each based on her

Weight, from purely organic amine, while the rest of these mixtures from the antioxidative organosilicon compounds consists.

The antioxidative organosilicon compounds or their mixtures with the known antioxidants are usually added to the high-temperature lubricating oils by simply mixing them. In In some cases it may be advisable to heat the lubricating oils in order to contain the antioxidants to solve. If the mixtures of antioxidants are used, their constituents can be used together or be incorporated separately into the lubricating oil.

The preparation, described in the following examples, of silanes used according to the invention, which can of course also be obtained by other processes, were carried out under nitrogen.

example 1

a) 46.0 g (0.22 mol) of diphenylvinylchlorosilane and 45.6 g (0.20 mol) of p-bromo-N, N-diethylaniline were mixed with 50 ml of tetrahydrofuran and blended into a mixture over a period of 2 hours 250 ml of tetrahydrofuran and 5.3 g (0.22 mol) of magnesium turnings added, the temperature being kept below 45 ° C. When the addition was complete, the reaction mixture was refluxed for 45 minutes. The reaction mixture was then hydrolyzed and the residue was recrystallized from ethanol and then from hexane. The thus obtained (p - diethylaminophenyl) - diphenylvinylsilan had mp 67-70 ⁰ C..

b) 43.8 g (0.20 mol) of diphenylchlorosilane and 47.9 g (0.21 mol) of p-bromo-N, N-diethylaniline were mixed with 50 ml of tetrahydrofuran and blended into a mixture over a period of 2 hours 100 inl of tetrahydrofuran and 5.28 g (0.22 mol) of magnesium turnings added, the temperature being kept below 45 ° C. After the addition had ended, the reaction mixture was refluxed for 1 hour. The reaction mixture was then hydrolyzed and the residue was recrystallized from hexane. The thus obtained (p-diethylaminophenyl) -diphenylsilan had mp. 58-59 ⁰ C.

c) From 24.3 g (1 mol) of magnesium and 228 g (2 mol) of p-bromo-N, N-diethylaniline in tetrahydrofuran a Grignard adduct was prepared, which in a period of 40 minutes in a mixture of 272 g (2 mol) of methyltrimethoxysilane was added to tetrahydrofuran, the temperature Reached 55 ° C. The tetrahydrofuran was then distilled off and the residue was taken up in toluene. The end product was distilled at 125 to 130 ° C / 2mm Hg and (p-diethylaminophenyl) methyldimethoxysilane obtained in 39.4% yield.

Example 2

According to the procedure described in Example 1, the stated amounts of the following starting materials were implemented. The products obtained thereby became commercially available after purification Triheptanoate of 1,2,2-trimethylolpropane added in the following concentrations, each based on the weight of the lubricating oil. This resulted in an increase in the oxidation resistance and heat resistance of the lubricating oil, respectively.

Grignard adduct

product

Concentration in the lubricating oil

1.0,30MoI

(C ₈ H ₁₇ J ₂ N

2. 0.30 moles
(C ₃ H ₇ J ₂ N

3. 0.30 moles

(C ₂ Hs) ₂ N

MgX

MgX

MgX

0.15 moles
(C ₆ H ₅ ) (CH ₂ = CH) SiCl ₂

0.15 moles
(C ₆ H ₅ ) Si (OC3H ₇ ) ₃

0.15 moles
(CH ₂ = CH) Si (OC ₂ Hs) ₃

(C ₈ H ₁₇ J ₂ N

(C ₃ H ₇ J ₂ N

(C ₂ Hs) ₂ N

Si (C ₆ H ₅ ) (CH = CH ₂ )

Si (C ₆ H ₅ ) (OC ₃ H ₇ )

i (OC ₂ H ₅ ) (CH ₂ = CH)

1.0

0.2

5.0

Corresponding results were obtained with the trin-heptanoate of 1,1,1-trimethylolethane, tri-n-pentanoate of 1,2,2-trimethylolpropane, tetra-n-heptanoate of pentaerythritol, di-n-heptanoate of 2-butyl-2-ethyl-1,3-propylenediol, Di-n-octanoate of 2,2,4-trimethyl-1,3-pentanediol, di-n-heptanoate of neopentyl glycol, Bis (2,2,4-trimethylpentyl) sebacate, bis (1-methylcyclohexylmethyO-sebacate and bis (1-methylcyclohexylmethyl) adipate obtained in place of the tri-n-heptanoate of 1,2,2-trimethylolpropane.

Each of the antioxidants was combined with the triheptanoate in the amounts shown in the table below of the 1,2,2-trimethylolpropane mixed.

The durability of the lubricating oil was determined by heating the oil to 218 ° C. while passing through Air, determined at a rate of 8 liters of dry air per hour per 20 g of the lubricating oil. The air was, through a tube with an inside diameter 15.87 cm into the oil. After 24 hours, the amount of solids formed was (Mud) observed. The concentration of the antioxidants is in percent by weight based on the weight of the lubricating oil.

Antioxidants

1. none
2. l% phenyl-a-naphthyl-

amine

3. 2 ^u / o phenyl-a-naphthylamine

Solids

moderate solids content moderate solids content

moderate solids content

continuation

Antioxidants

4. 0.5o / o bis (p-diethylaminophenyl) dimethylsilane,

0.5% phenyl-a-naphthylamine

5. 1% (p-diethylaminophenyl) -trimethylsüan, 1% phenyl-a-naphthylamine

6. 2% (p-dimethylaminophenyl) trimethylsilane

7. 1% (p-diethylaminophenyl) methyldimethoxysilane,

1% phenyl-a-naphthylamine

8. 1% (p-diethylaminophenyl) diphenylsilane, 1% phenyl-a-naphthylamine

9. 0.5% (p-diethylaminophenyl) diphenylsilane

Solids

red-brown, moderate solids content

moderate solids content in the oil and on the Test tube

high solids content

clear - no solids

clear - no solids

clear - no solids

15th

20th

Nos. 4, 5 and 6 are antioxidants according to U.S. Patent 2,779,738.

From these experiments it is clear that in the lubricating oil with the addition of commercially available organic amines alone (# 2 and # 3), as well

30th

in admixture with antioxidants according to U.S. Patent 2,779,738 (Nos. 4 and 5), as well as in the case of antioxidants according to the aforementioned US patent specification alone (No. 6), considerable sludge formation occurred under the test conditions, while the lubricating oil with the addition of the antioxidants according to the invention both alone (No. 9) as well as in a mixture with organic amines (No. 7 and 8) remained clear without traces of sludge formation.

Claims (1)

Claim: High-temperature lubricating oil based on organic carboxylic acid esters, optionally containing known organic amines, characterized by a content of 0.1 to 5 percent by weight of a compound of the general formula R, N wherein R is alkyl radicals with 1 to 10 carbon atoms, R 'is hydrogen, alkyl radicals with 1 to 10 carbon atoms, phenyl, vinyl or alkoxy radicals with 1 to 4 carbon atoms and η is 1, 2 or 3, but at least one of the radicals R 'is hydrogen, a vinyl or an alkoxy radical having 1 to 4 carbon atoms. Considered publications:
U.S. Patent No. 2,779,738. 809 518/616 3.68 © Bundesdruckerei Berlin