CS196130B1 - Process for preparing oil of methylphenylpolysiloxane - Google Patents

Description

The invention relates to a process for the preparation of methylphenylpolysiloxane oil for the preparation of hydraulic fluids suitable for use in aircraft technology.

Methylphenyl polysiloxane oils for various uses are prepared by the hydrolysis of methylphenyldichlorosilane or by the hydrolysis of methylphenyldichlorosilane and dimethyldichlorosilane or dimethyldichlorosilane and diphenyldichloro, silane. Cohydrolysis results in a mixture of predominantly cyclic substances, which is subjected to linearization with sodium or potassium hydroxide, for example according to V. Brit. U.S. Pat. Other methods of linearization are also known, for example using sulfuric acid and the like.

Methylphenylsiloxane oils are widely used, especially in the electrical and engineering industries, where, among other things, lubricating effects are used under extreme conditions. They are used either alone or in admixture with other substances, such as, for example, to achieve the excellent properties of synthetic aviation motor oils. They have also found use as part of hydraulic fluids in aviation technology. However, the existing types of polysiloxane oils did not allow their full utilization in hydraulic fluids, since they cannot be achieved at satisfactory flash points of the required viscosities at temperatures around -60 ° C and the oils do not sufficiently dissolve additives of various kinds whose additive significantly affects the hydraulic fluid's functional properties. obtaining optimal properties at low temperatures, for example around -60 ° C, and at the same time at temperatures higher for example 205 ° C.

It has now been found that the methylphenylpolysiloxane oil prepared according to the invention has proved to be the basis for hydraulic fluids, allowing a considerably higher additive addition under these conditions.

The process for the preparation of methylphenylpolysiloxane oil by cosdrolysis of diphenyldichlorosilane and dimethyldichlorosilane, by equilibration of the resulting cohydrolysate, followed by distillation and rectification, consists in carrying out cosdrolysis of diphenyl and dimethyldichlorosilane in mass. a ratio of 1: 3.5 to 1: 4.5 and equilibration is performed with the addition of hexamethyldisiloxane in an amount of 20 to 25 percent by weight. based on the cohydrolysate and distilled at a pressure of 130 Pa to a b.p. 370 ° C, low molecular weight fractions were separated from the distillate at a pressure of 1470 Pa to a b.p. 165 ° C.

The examples below illustrate embodiments of the invention.

Example, 1

A mixture of 253 g of diphenyldichlorosilane and 1032 g of dimethyldichlorosilane was cosdrolyzed by adding to 2 L of water with stirring at 80 ° C to 90 ° C. After separation of the hydrochloric acid, the cohydrolysate was adjusted by heating to 90 ° C and distilling off the volatiles at a pressure of 13,000 Pa. The remaining cohydrolysate was equilibrated with the addition of 160 g of hexamethyldisiloxane with the addition of sulfuric acid. After separation of the sulfuric acid and neutralization of the oil, the high-molecular fractions were separated from the oil by distillation at 130 Pa to a boiling point of 370 ° C and the low-molecular fractions were rectified at 1470 Pa to t 165 ° C. After filtration, an oil was obtained, 96130 having a pour point below -70 ° C, b. Flashing 185 ° C, viscosity at -60 ° C 1600 mm ² ss, and at 200 ° C 1.5

Example 2

Hydrolysis of a mixture of 253 g of diphenyldichlorosilane and 960 g of dimethyldichlorosilane was accomplished by addition to 2 L of water with stirring at 80-90 ° C. After separation of the hydrochloric acid, the hydrolyzate was adjusted by heating to 90 ° C and distilling off the volatiles at a pressure of 13,000 Pa.

Claims (1)

A process for the preparation of methylphenyl polysiloxane oil by cosdrolysis of diphenyldichlorosilane and dimethyldichlorosilane in a weight ratio of 1: 3.5 to 1: 4.5 by equilibration with the addition of hexamethyldisiloxane in an amount of 20 to 25% by weight. based on cohydrolysate, subsequent The remaining cohydrolysate was equilibrated with the addition of 150 g of dexamethyldisiloxane with the addition of sulfuric acid. After separation of the sulfuric acid and neutralization of the oil, high-molecular fractions were separated from the oil at a pressure of 130 Pa to a boiling point of 370 ° C and by low-molecular rectification at a pressure of 1470 Pa to a b.p. of 162 ° G. After filtration, an oil was obtained with a pour point below -70 ° C, a flash point of 182 ° C, a viscosity at -60 ° C of 1250 = 1.4456 with a viscosity index of 370. Y N E L Z Z by distillation and rectification, characterized in that it is distilled at a pressure of 130 Pa to rt. The low molecular weight fractions were separated from the distillate by rectification at a pressure of 1470 Pa to a melting point of 165 ° C.