CS242252B1 - Methylphenylpolysiloxane oil - Google Patents

Description

(54) Methylphenylpolysiloxane oil

The present invention relates to methylphenylpolysiloxane oil for hydraulic fluids suitable for use in aviation technology and as brake fluids.

Methylphenylpolysiloxane fluids for various uses are prepared by hydrolyzing methylphenyldichlorosilane or methyl, phenyldichlorosilane and dimethyldichlorosilane or dimethyldichlorosilane and diphenyldichlorosilane.

Cohydrolysis results in a mixture of predominantly cyclic substances, which is subjected to linearization with sodium or potassium hydride, e.g. V. Brit. E. Other methods of linearization are also known, for example using sulfuric acid and the like.

Methylphenylpolysiloxane oils are widely used especially in the electrochemical 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 superior 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 containing, in addition to these oils, diesters of higher dicarboxylic acids and additives, since they cannot be obtained at satisfactory flash points of the required viscosities at temperatures of about -60 ^, of various kinds, the addition of which greatly affects the functional properties of the hydraulic fluid and the further possibility of obtaining optimum properties at low temperatures, for example around -60 ° C and at higher temperatures, for example 206 ° C.

It has now been found that the methylphenylpolysiloxane oil, which is the essence of the present invention and is characterized by the general formula (CH 2 Si-O), has a significant effect on the performance of hydraulic fluids.

CH * I ^J 1 Sl-0 -— Sí-o j j CH 2 rx

-Si (CH ₃ ) ₃ m

wherein n and m are molar amounts and have a value of in = 1.2 to 14 and m = 0.15 to 0.53.

The oil according to the invention is prepared by hydrolysing a mixture of diphenyldichlorosilanes and dimethyldichlorosilanes, equilibrating with the addition of hexamethyldisiloxane in proportions corresponding to the theoretical composition of the formula and distillation to boiling point 135 + rp 8 ° C at 1330 p, and filtering the distillation residue obtained.

At a lower distillation stage an oil with an insufficient flash point is obtained, at a higher one an oil with an unsuitable viscosity at -60 ° C is obtained. Application of the new metylfenylpolysiloxanového oils as components of hydraulic fluids has been removed the need to use substantial amounts of higher diesters of dicarboxylic acids having carbon number 6 to 10 and achieving acceptable working viscosity of such liquids at -60 ^Q C

The examples below illustrate the preparation and composition of the oil of the invention. Example 1 and d 1

A cosdrolysis of a mixture of 38 g of diphenyldichlorosilanes was performed by admitting to 3.2 L of water with stirring at 70 ° C. After separation of hydrochloric acid, 102 g of hexamethyldlsiloxane was added to the obtained hydrolyzate and equilibration was carried out with the addition of sulfuric acid.

After separating the sulfuric acid and neutralizing the oil, the volatiles were distilled off at a pressure of 1330 Pa to a boiling point of 127 degrees C. Ρ ο filtration yielded 62: 8 g of oil (77% yield) with a freezing point below -70 ° C, a flash point of 180 ° C, a viscosity at 200 ° C 1.9 mm. ^2, sec. ¹ (at -00 C ^and a viscosity of 217 mm ^2. sec. ^1.

The mixture containing 6 parts by weight of the prepared oil, 4 parts by weight of bis-2-ethylhexyl sebacate and 3 parts by weight of a mixture of antioxidant and anticorrosive additives was homogenized at 120 ° C. The liquid obtained was clear at -50 ° C.

Example 2

A mixture of 83.5 g of diphenyldichlorosilane and 1550 g of dimethyldichlorosilane was cosdrolyzed by admitting to 2.8 L of water with stirring at 70 ^and C. After separating the hydrochloric acid, 312 g of hexamethyldisiloxane was added to the obtained hydrolyzate, and equilibration was carried out with sulfuric acid. After separating the sulfuric acid and neutralizing the oil, the volatiles were distilled from the oil at a pressure of 1330 Pa to a boiling point of 13: 5 degrees C.

After filtration, 998 g of an oil (79% yield) having a pour point below -70 ° Ό, a flash point of 185 ° C, and a viscosity at 200 ° C of 2.1 mm ² , sec. ¹ and at a temperature of -60 ° C 3.35 mm ² . sec. ¹ .

Example 3

Was co-hydrolysis of a mixture of 134 g and 1550 g difenyldichlorsilanů mating dimethyldichlorosilane in 2.9 1 of water at 70 for ^{mťchání, 0)} C. After separation of hydrochloric acid was added to the obtained kohydrolyzátu 160 g hexamethyldisiloxane and equilibration carried out with the addition of sulfuric acid.

After separating off the sulfuric acid and neutralizing the oil, the volatiles were distilled from the oil at a pressure of 1330 Pa to a boiling point of 14: 3 degrees C. After filtration, 940 g of oil (81% yield) with a pour point below -70 ° C, flash point were obtained. 190 ° C, a viscosity at 200: C 2.3 mm ^2nd sec. ¹ and at a temperature of -60 ° C 417 mm ^2nd sec. ^1.

The oils obtained by the process according to the invention form homogeneous mixtures with diesters of diicarboxylic acids up to -60 ° C.

Claims (1)

BACKGROUND OF THE INVENTION iMethylphenylpolysiloxane oils of the general formula CHa I - ³ ^ 6 (CH2) -Si-O 1 Si ~ O | - Si-0 1 ^CH 3 rx CgH ₅ m -Si (CH ₃ ) ₃ where n m denotes a molar amount with a value of n = 12 to 15 and m = 0.15 to 0.53