DE1264659B - Lubricants for aircraft gas turbines - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

Number:
File number:
Registration date:
Display day:

ClOm

German class: 23 c -1/01

1264 659
C22706IVc / 23c
November 10, 1960
March 28, 1968

It is known that liquid diesters are obtained from dicarboxylic acids and straight-chain or branched saturated monovalent ones Use alcohols as lubricants.

The same are ester mixtures of dihydric alcohols and dicarboxylic acids or mono- and Dicarboxylic acids and ester mixtures from a trihydric alcohol, namely trimethylolethane with Mono- and dicarboxylic acids are known as lubricants. However, these lubricants meet the requirements The lubricants for modern aircraft gas turbines are now being put to use, not because they are do not have the required thermal stability at 325 ° C. Besides, the properties are this Ester lubricant does not remain sufficiently constant at low temperatures over a longer period of time, so that special additives are required to improve the low-temperature properties.

These disadvantages do not arise when using a lubricant which is a reaction product a mixture of ao

(A) one or more saturated aliphatic, straight-chain monocarboxylic acids with 1 to 18 carbon atoms, in particular 7 to 10 carbon atoms, with

(b) 1,1,1-trimethylolpropane and

(C) saturated aliphatic, straight-chain dicarboxylic acids with 4 to 14 carbon atoms or aromatic ones Dicarboxylic acids with 8 to 12 carbon atoms

in the molar ratio of (a): (b): (c) as (6 to 11): (2.5 to 5): 1. The viscosity properties of this Lubricants are better than the common diesters used as lubricants, so they stand out particularly suitable for use in aircraft gas turbines and extreme temperature conditions in Operation can be suspended.

The esterification of the constituents mixed together is carried out as usual, but preferably in the presence of an esterification catalyst, e.g. p-toluenesulphonic acid, sodium bisulphate, potassium pyrosulphate, a tetraalkyl titanate, titanium tetrachloride or molecular sieves with a pore diameter of 2 to 20 Å, in particular 4 to 10 Å.

The reactants can be reacted with one another in one, two or three stages by heating will.

The low-boiling compounds are distilled under reduced pressure, e.g. or less, stripped from the products.

The acid number of the product can be determined by washing with water, neutralizing or cleaning solvent lubricants for aircraft gas turbines

Applicant:

Stuart Walter Critchley, Sharks Barns, Cheshire;

Peter Michael Blanchard,

West Molesey, Surrey (UK)

Representative:

Dr.-Ing. A. v. Kreisler, patent attorney,

5000 Cologne 1, Deichmannhaus

Named as inventor:

Stuart Walter Critchley, Sharks Barns, Cheshire;

Peter Michael Blanchard,

West Molesey, Surrey (UK)

Claimed priority:

Great Britain of November 11, 1959 (38 232) of February 23, 1960 (6309) - -

solutions, e.g. dilute alkali, dilute oxidizing agent or dilute reducing agent solutions, be lowered.

Suitable monocarboxylic acids (a) are capric acid, n-valeric acid, isovaleric acid, enanthic acid, caprylic acid, Pelargonic acid, propionic acid and benzoic acid.

example

In one with a water trap according to Dean and Heavily studded flasks were those in the following Table 1 listed ingredients in the amounts indicated there. It was on Heated to reflux until no more water was formed. Served as a towing center] for the separated water Toluene. After the completion of the reaction, the product was washed with dilute aqueous sodium carbonate solution washed and dried. The toluene was removed by vacuum stripping The water bath was removed and the refining of the product was carried out by stripping to a temperature of 200 ° C at 0.1 / 0.2 Torr to the end.

The Esterprodukte obtained were tested for viscosity at 99 ⁰ C. The one for each of the

809 520/609

The value resulting from the reaction products is also shown in Table 1 below.

Table 1 W. X Y Z - ¹ to to to 2
8th
4-
1 2
5
3
1 Capric acid 24.25 8.2 10.2 10
.4
1 Caprylic acid 7.4 1,1,1-trimethylol propane ..
Sebacic acid Viscosity at 99 ° C, cSt ...

IO

For the preparation of the ester W, the ingredients were in a mixing ratio known from the prior art for comparable components put together; the ester products X, Y and Z are lubricants used in the present invention.

The viscosity values determined for the viscosity of the Products at 99 ° C show that the lubricants according to the invention are particularly close to those for the desired viscosities of about 7 to 8.5 cSt, while the comparative product, the ester W, has a considerably higher viscosity at 99 ° C.

The individual ester products were now adjusted to the optimum viscosity of 7 to 8 cSt at 99 ° C in such a way that they are mixed with corresponding amounts of a simple triester, namely the tricaprylic acid ester of trimethylolpropane (hereinafter referred to as Triester T), were mixed until mixtures were formed, whose viscosity at 99 ° C. was in each case between 7 and 8 cSt, preferably about 7.5 cSt.

In the case of the ester product W, a relatively large amount of triester T had to be added, While in the case of the ester products X, Y and Z used according to the invention, already a relatively small amount of triester T was enough to achieve the desired viscosity, so that in these in the latter cases most of the mixture consisted of the complex ester. The reason for this lies in that the proportions in which the constituents are implemented in the preparation of the complex ester the formation of a substantial proportion of molecules of the monocarboxylic acid triester of trimethylolpropane favor. [It should be noted that the expression "complex esters" is self-evident denotes the total ester product of the reaction of reactants a), b) and c), the one Represents a mixture of different types of EstermoJekulen.]

With the products manufactured from the Esterprodukten W, X, Y, and Z mixtures tests were carried out (2497 DERD) "set out method for thermal stability at 325 ⁰ C after in" The British Ministry of Aviation Target Specification. This specification deals with lubricants for modern aircraft gas turbines operating under conditions too harsh for the commercially available synthetic lubricants currently available (ie 1960). For example, while currently available lubricants need to be thermally stable only at 28O ⁰ C, calls for the specification DERD 2497 good thermal stability at 325 ° C, and indicates that the percentage change in viscosity at 99 ° C for 6, 12 , 18- and 24-hour treatment at 325 ° C must in no case be outside the limits of -10 to + 20%.

The results of this test of the ester products W, X, Y and Z are listed in Table 2 below:

Tabel

lubricant 0 hours Kinematisc
6 hours : hey Viscosity at 99 °
12 hours I C after
18 hours 24 hours 37% W + 63% T 7.51 6.61
(-12.0) 6.58
(-12.4) 6.81
(-9.3) 6.76
(-8.9) 89% X + 11% T 7.69 7.40
'(-3.7) 7.63
(-0.8) 7.90
(+2.7) 8.06
(+4.8) 65% Y + 35% T 7.28 6.93
(-4.8) 7.04
(-3.3) 7.01
(-3.6) 7.14
(-1.9) 100% Z 7.45 7.52
(+0.9) 7.55
(+1.3) 7.82
(+5.4) 8.07
(+6.8)

The percentages given for the esters relate to percentages by weight. The numerical values in brackets are the percentage changes in viscosity.

From Table 2 it can be seen that the esters used according to the invention on their own (ester product Z) or after the addition of relatively small amounts of the tricaprylic acid ester of trimethylolpropane (ester products X and Y) have excellent thermal stability at 325.degree. have, during Ver _r equal sester W is a viscosity decrease of 12.0% already during the first 6 hours' treatment at 325 ° C, which still increases slightly upon further 6 hours of treatment at -12.4%. This shows that this comparative tester does not meet the requirements of the DERD 2497 specification. The other currently (1960) available han · ¹ · mercial synthetic aircraft gas turbine lubricant of the same viscosity decompose at 325 ⁰ C.

Claims (1)

Claim: Use of the reaction product of a mixture of (a) one or more saturated aliphatic monocarboxylic acids with 1 to 18 carbon atoms, in particular 7 to 10 carbon atoms, with (b) 1,1,1-trimethylpropane and. (c) saturated aliphatic, straight-chain dicarboxylic acids with 4 to 14 carbon atoms or aromatic dicarboxylic acids with 8 to 12 carbon atoms in the ratio of (a): (b): (c) like (6 to 11): (2.5 to 5): 1 as a lubricant for aircraft gas turbines. Considered publications: German Patent No. 956 341; French Patent No. 1110 221; U.S. Patents Nos. 2,499,983, 2,588,194, 628,974.2 860119; British Patent Nos. 680,438, 697,412, 618. When the application was announced, two priority documents were displayed.