DE1925048B1 - Lubricants or power transmission agents based on dicarboxylic acid esters - Google Patents

Description

As a lubricant, especially for turbine engines in subsonic aircraft or as a power transmission means for use under extreme temperature conditions oils must meet certain requirements, such. B. in USA Military Specification MIL-L-007808 F «. With regard to viscosity-temperature behavior, low-temperature viscosity and These lubricants must comply with the following limit values at their flash point: Viscosity over 3 cSt at 98.9 ° C, below 1300OcSt at -53.9 ° C, flash point above 204 ° C, pour point below -60 ° C. Above In addition, certain requirements for corrosion and oxidation stability are made for the esters the guidelines have been established by standards.

As is generally known, esters of sebacic acid have mainly been used for these purposes up to now (see Gunderson and Hart, Synthetic lubricants, New York 1962, Chapter 5, Dibasic acid esters).

The constantly growing need for high-quality lubricants and power transmission media arose the object underlying the invention, from easily accessible, in large quantities on the The alcohol and acid components on the market for ester oils that are easy and economical to produce Use as a lubricant, especially for turbo jet aircraft, and as a power transmission medium to develop that meet the above-mentioned requirements.

It has now been found that lubricants or power transmission means fulfill this purpose, which consist of

55 to 70 percent by weight hexane -1,6 - diol - iso-

nonanate ethyl hexanate,

15 to 30 percent by weight 2.2 - dimethylpropane

diol pelargonate nonanate and 10 to 20 percent by weight octyl nonyl trimethyl

adipate
exist.

Oils with the following composition show particularly advantageous properties:

60 to 65 percent by weight hexane -1,6 - diol - iso-

nonanate ethyl hexanate, 20 to 24 percent by weight 2,2-dimethylpropane

diol pelargonate nonanate and 13 to 17 percent by weight octyl nonyl trimethyl

adipate.

Each of these esters is composed of three different components. The ones from the glycols The esters formed are created by reacting the alcohols with two monocarboxylic acids each, the trimethyladipic acid ester is obtained by reacting the acid with the two monoalcohols. The components are here according to any known Esterified process.

The ester oil according to the invention is obtained by simple mixing, still known Add additives to increase the oxidation stability and to prevent foam formation can.

The individual components do not meet the requirements described above, as can be seen from the data compiled below: For example, the ester 2,2-dimethylpropane -1,3-diol-isononanate pelargonate, which is thermally and oxygen-stable due to the quaternary carbon atom, has a low-temperature viscosity of 10200 cSt at -53.9 ° C, a pour point of -70 ° C, a flash point of 208 ° C; However, its viscosity of 2.94 cSt at 98.9 ° C is below the permissible value of 3 cSt. The ester n-oxo-octyln-oxo-nonyl-trimethyladipate, which is also particularly heat- and oxygen-resistant due to its structure, meets the requirements with regard to its viscosity of 3.2 cSt at 98.9 ° C, its flash point of 229 ° C and his Pour point of -69 ° C after; however, its low-temperature viscosity of 17100 cSt exceeds the limit value of 13,000 cSt. Hexane (l, 6) diol isononanate ethylhexanate meets all the required, conventional characteristics of the viscosity of 3.17 cSt at 98.9 ° C, the low-temperature viscosity of 1180OcSt at -53.9 ° C, the pour point of - 70 ⁰ C and a flash point of 217 ° C, but its heat and oxidation resistance is lower than that of the other two esters.

It was not foreseeable that a mixture of the three components in the ratio according to the invention results in an oil with excellent properties for the purposes mentioned.

For example

A mixture of the following components was made:

63 weight percent hexane-1,6-diol-3,5,5-trimethyl-

hexanate-2-ethylhexanate,
22 percent by weight 2,2-dimethylpropane-1,3-diol-

pelargonate-3,5,5-trimethylhexanate,
15 percent by weight η - oxo - octyl - η - oxo - nonyl trimethyl adipate.

The properties of this mixture are summarized in the following table. How from here As can be seen, all analysis data of this ester mixture correspond to specification MIL-L-007808 F.

exam on

limit Definite value at least 3.0 cSt 3.44 cSt at least 11, OcSt 13.49 cSt maximum 1300OcSt 12498 cSt maximum + 6% 12414 cSt at least 204 ⁰ C 223 ° C below -6O ⁰ C below -67 ° C maximum 35% 30.6 percent by weight

Viscosity (DIN 51562)

at 98.9 ° O

at 37.8 ° C

at -53.9 ° C

after a further 3 hours at -53.9 ° C

Flash point (ASTMD 92) at 760 Torr: ".,

Pour point (ASTMD 97)

Loss of Evaporation (ASTMD 972) (6V ₂ hours,

204 ⁰ C)

continuation

Check for limit value

Definite value

Corrosion and oxidation stability (FTM 791 a-5308) (72 hours / 175 ° C)

stole

silver

copper

MgAl ₆ ;

AlCuMg ₂

Viscosity at 37.8 ⁰ C after aging (72 hours /

175 ° C)

Total Acid Number After Aging (ASTMD 664)

(72 hours / 175 ° C)

Lead corrosion (FTM 791a-5321) (1 hour / 163 ° C) .. Silver corrosion (FTM 791 a-5305) (50 hours / 232 ° C) Copper corrosion (FTM791 a-5305) (50 hours / 232 ° C) ± 0.2 mg / cm ²
± 0.2 mg / cm ²
± 0.4 mg / cm ²
± 0.2 mg / cm ²
± 0.2 mg / cm ²

-5 to 15%

maximum 2.3 mg KOH / g
maximum 6 mg / squ. in.

3.0 mg / squ. in.
3.0 mg / squ. in.

+0.04 mg / cm ² +0.07 mg / cm ² +0.06 mg / cm ² +0.05 mg / cm ² +0.03 mg / cm ²

less than 1%

0.24 mg KOH / g-1.27 mg / squ. in. 0.3 mg / squ. in. 2.8 mg / squ. in.

The alcohols used to make these esters were obtained through OXO synthesis and hydrogenation the aldehydes obtained in this way. The alkyl radicals denoted by n-OXO are derived from OXO-alcohol mixtures obtained by hydroformylation of n-olefins.

The ester n-oxo-octyl-n-oxo-nonyl-trimethyl adipate has not yet been described. It is useful in that described in Example 2 Way made.

Example 2

^{In a 10 l round bottom flask, 100 cm 3 of} cumene as an entrainer and 3 g of paratoluenesulfonic acid as a catalyst were added to a mixture of 2256 g of trimethyladipic acid, 1720 g of n-OXO-octanol and 1720 g of n-OXO-octanol and 1SSOgn-OXO-nonanol. The solution was refluxed for 5 hours with stirring at a temperature of 155 ° C. that established itself. During this time, the theoretical amount of water formed of 432 ml was carried out with the entrainer and separated off with the aid of a water separator attached to the side. The cumene was driven off from the reaction product by distillation under the vacuum of a water jet pump. The unreacted and only partially reacted portions were separated from the cumene-free reaction product in two fractions by vacuum distillation. The first fraction obtained from 50 to 140 ° C. under a vacuum of 0.1 torr was 370 g and contained the acidic components. The second fraction passed over in a temperature range of 110 to 154 ° C at 0.002 torr in an amount of 395 g. The residue of 4660 g of this distillative separation represented the desired crude ester oil.

The yield was thus 91%. The neutralization number of the ester was 0.1 mg KOH per gram and the ester number 264 mg KOH per gram By distilling the ester to a residue of 90 g under a vacuum of 0.001 Torr , a water-white product with the following characteristics was obtained :

Density df 0.918

Viscosity in cSt

at 98.9 ⁰ C 3.21

at 37.8 ° C 12.5

at -40 ⁰ C 2110

at -53.9 ° C 17 100

Viscosity index 139

Pour point, "C -69

Flash point, ⁰ C 229

Claims (2)

Patent claims: 1. Lubricant or power transmission medium, consisting of 55 to 70 percent by weight of hexane-1,6-diol-iso- nonanate ethyl hexanate, 15 to 30 percent by weight 2,2-dimethylpropane diol pelargonate nonanate and 10 to 20 percent by weight octyl - nonyl - trim- ethyl adipate 2. Lubricant or power transmission medium according to claim 1, consisting of 60 to 65 percent by weight of hexane-l, 6-diol-iso- nonanate ethyl hexanate, 20 to 24 percent by weight 2,2-dimethylpropane diol pelargonate nonanate and 13 to 17 percent by weight octyl - nonyl - trim- ethyl adipate.