DE961382C - Synthetic lubricant - Google Patents

Description

ISSUED APRIL 4, 1957

St 8938 IVc 133 c

A number of synthetic organic compounds are used as lubricants, especially for lubrication of aircraft gas turbines, e.g. B. those with a jet or propeller engine are known.

The synthetic lubricants according to the invention include monoesters, diesters, polyesters, ether esters, Glycols, polyglycols including polyalkylene glycols, ether glycols, complex esters, formals, polyformals, complex formals or mixtures of these compounds. The term lubricant components in For the purposes of the invention, these synthetic compounds and mixtures of compounds encompassed.

Diesters describe inter alia. British Patents 6oo 325, 664 052 and 668 663. Diester can are made from dicarboxylic acids with 2 to 40 carbon atoms that are straight-chain or branched are saturated or unsaturated or have at least one ether or thioether bond. as Acids for diester production include: To mention adipic acid, azelaic acid, sebacic acid. The dicarboxylic acids can be converted to diesters with alcohols that have 1 to 40 carbon atoms and are straight or branched chain, e.g. B. 2-ethylhexanol and isooctanol. Have special meaning

the alcohols produced by oxo synthesis, namely those with 5 to 12 carbon atoms. For the Esterification of the dicarboxylic acids is particularly suitable for ether or thioether alcohols (British Patents 664 052 and 668 663).

Glycol ethers are derived from glycol or polyglycols, preferably polyalkylene glycols, in which the Glycols themselves have ether or thioether bonds and one or both terminal hydroxyl hydrogen atoms are replaced by substituents by means of etherification.

Formal are given by the formula

A-OCH ₂ -OB, polyformals by the formula

AO (CH ₂ O) ₈ -B

and complex formals using Formula 20

AO (CH ₂ ), - [C-0 (CH ₁₁ O) J,

represented, wherein A, B and C identical or different organic groups with 1 to 20 carbon atoms and x, y and 2 is an integer equal to or greater than ι. In these formulas, all or some of the oxygen atoms can be replaced by sulfur atoms.

Complex esters arise from two or more

Compounds of the following groups: monohydric or polyhydric alcohols, monobasic, dibasic or other polybasic organic acids including oxyacids, glycols or polyglycols, with at least a polyfunctional acid and at least one polyfunctional alcohol are reacted.

Representatives of the complex esters particularly suitable for the present invention have the following structure: Alcohol - dibasic acid - polyglycol - dibasic acid - alcohol - taking as alcohol 2-ethylhexanol or isooctanol, as dibasic acid sebacic, adipic or azelaic acid and as polyglycol a polyethylene glycol with a molecular weight of about 200 come into consideration.

The synthetic lubricants mentioned have a tendency to oxidize, especially when exposed to heavy use. B. about 1 or 2%. Suitable anti-oxidants are, for. B. di- and trihydric phenols, aromatic nitro compounds, aromatic amines, aromatic amine sulfides such as phenothiazine (thiodiphenylamine) or sulfur-containing cyclic compounds such as thiophenes, also thioalcohols, phosphorus and sulfur-containing organic compounds such as thiophosphates.
The lubricant must meet the required lubrication conditions, including the required viscosity and a suitable viscosity temperature behavior, also have a favorable pour point and flash point and lubricate effectively under all relevant conditions even under high loads; this applies in particular to lubricants for aircraft gas turbines.

Synthetic lubricants have been used with success in aircraft gas turbines. In the course of however, development has created a need for lubricants of varying degrees of viscosity while maintaining or improving other properties. Complex esters according to the British patent specification 687 346 with a kinematic viscosity of about 8 cSt at 99 ° were found to be suitable for the current gas turbines. Newer types, however, require a viscosity of around 3 cSt at 99 ° with preservation a suitable load capacity and favorable viscosity temperature behavior at the operating temperatures. The present invention aims to improve resilience improve synthetic lubricants and bring them to the required viscosity, so that they can be used for gas turbines. It has now been found that synthetic lubricants, in particular diesters or mixtures thereof to the desired viscosity, e.g. B. in particular at high temperatures, brought at the same time with regard to the viscosity temperature behavior and the Resilience can be improved by the fact that small amounts of one or more in the lubricants soluble halogen and / or sulfur-containing polymers are introduced. The additional amount should not exceed 10 percent by weight, based on the total mixture, and preferably 0.01 to 5 percent by weight, in particular 0.05 to 3, and 0.1 to 2 percent by weight. Only such polymers should be used in the lubricants at the required concentrations and below occurring operating conditions are soluble.

Examples of polymers according to the invention are haloprene rubber, such as polychloroprene, polyvinyl and Polyvmyhdenchlori.de and polyvinyl chloride acetate copolymers. Other compounds are polychlorotrifluoroethylene and polyalkylene sulfides, polydichlorostyrene, Polychlorostyrene and poly-2,3-dichlorobutadiene. Polyvinyl chloride and polychloroprene are preferred.

The polymers are expediently used in the unvulcanized state in order to achieve dissolution in the lubricants with certainty; they may be prepared by simply mixing into the lubricant at a higher temperature, preferably about 35-125 ⁰ dissolved.

In order to show the improvement in the viscosity at 99 ° and the maximum load (test in the SAE machine), diesters and mixtures thereof with complex esters with and without the addition of the polymers were tested and the results were compiled in Table I. Dioctyl adipate was tested for itself and after introducing ι percent by weight of polyvinyl chloride by dissolving; the results were compared to Mixture A which contained 3 percent by weight of a known stress additive, namely tricrexyl phosphate. Mixture A consisted of 95% dioctyl sebacate, 5 ° / ₀ of a complex ester of polyglycol - sebacic -, Diäthylhexanol and tricresyl phosphate. There * ^ao, it was found that 1% polyvinyl chloride up to the value of the mixing A increased the viscosity of dioctyl adipate of 2.4 to 4.3 cSt at 99 ⁰ and the maximum load capacity.

Similarly, dioctyl sebacate was improved in performance by the addition of 1% polyvinyl chloride

that of the mixture B of 5 cSt at 99 ° was adjusted. Mixture B, currently used as a lubricant for Gas turbines in use, consists of 65% dioctyl sebacate and 35% of the complex ester used for mixture A.

Similar improvements were made with 0.5% polychloroprene.

Mixture C consisted of 40% dioctyl sebacate and 60% of the complex ester used for Mixture A.

Corresponding tests were also carried out to the viscosity-temperature behavior, and the viscosity at 99 ° compared to the -40 ⁰ to determine. These and other results are shown in Table II.

Table I.

Ester mixtures

chlorine

0 / / 0 viscosity
in cSt at 99 ⁰

SAE Maximum Load, lbs. (1000 rpm, ratio 3.4: 1)

D. 0. A. ¹ )

_1S DOA + i% PVC ² )
Mixture A

DOS ³ )

DOS + i% RV. C.
Mixture B

D. O. S

DOS + 0.5% PC Γ
-Mixture A

_a "Mixture C

Mixture C + 3% P. C. P.

no

0.56 none

no 0.56 no

no 0.18 no

none 0.12 2.4 4.3 3.6

3.2
5, o
5, o

3.2
3.5
3.6

7.5
8.1

85 125 125

110

^X 45 140

110 200 125

145 175

¹ J DOA = dioctyl adipate. ² ) PVC = polyvinyl chloride. ³ ) DOS = dioctyl sebacate. ⁴ ) PCP = polychloroprene

Table II

Ester mixture

Kinematic viscosity cSt at 99 ° 1-40 ° ASTM slope

Pour point ⁰ C

D. O.A.1)

DOA + 1% RV. C. ³ ).
DOA + 0.75% RV.C.
Mixture A

DOS ² ) + 0.5% R C. R

Mixture C

Mixture C + 0.3% PCP ⁴ )

2.40 4.26 3.66 3.6o

3.52 7.92 865
2,440
1.060
1,900

1,600
12,800
14.200

0.76 0.67 0.67 0.69

0.69 o, 59 o, 59

') DOA = dioctyl adipate. ^B ) DOS = dioctyl sebacate. ³ ) PVC = polyvinyl chloride. ⁴ ) PCP = polychloroprene.

Claims (3)

PATENT CLAIMS: I. Synthetic lubricants made from one or more synthetic lubricant components, characterized by a content of 0.01 to 10 percent by weight, based on the total mixture, one or more halogen and / or sulfur-containing polymers that are soluble in the lubricant. 2. Synthetic lubricant according to claim i, characterized by a content of polyvinyl chloride. 3. Synthetic lubricant according to claim i, characterized by a content of haloprene rubber, preferably polychloroprene. © 609 617/461 8.56 (609 853 3.57)