CS259817B1 - Synthetic hydraulic fluid for motor vehicles - Google Patents

Abstract

Synthetic hydraulic fluid for motor vehicles for operating temperatures of -60 to 200 °C containing 90 to 100 parts by weight of ω,ω-dialkoxypolymethylsiloxanes of the general formula I CH, , δ RO-ISLO) - CHi CH, & íl) where x = 6 to 30, phenyltrialkoxysilane of the formula II as a swelling regulator, in an amount of 0 to 10 parts by weight of CeH5Sl(OR)3 (Π) where R denotes 2-ethylhexyl and a mixture of additives consisting of dioctyldiphenylamine or phenothiazine, phenyl-^-naphthylamine, quinizarin and a dye in an amount of 0.5 to 0.8 parts by weight.

Description

Synthetic hydraulic fluid for motor vehicles for operating temperatures from -60 to 200 ° C containing 90 to 100 parts by weight. ω, ω-dialkoxyplymethylsloloxanes of formula I

CH,, δ

RO-ISLO CHi

(X) wherein x = 6 to 30, the phenyltrialkoxysilane of formula II as a swellable regulator, in an amount of 0 to 10 parts by weight

CeH5Sl (OR) 3 (Π) where R is 2-ethylhexyl and a mixture of additives consisting of dioctyldiphenylamine or phenothiazine, phenyl-4-naphthylamine, quinizarin and dye in an amount of 0.5 to 0.8 parts by weight.

2S9B17

The invention relates to a synthetic brake fluid for motor vehicles based on α, ω-dialkoxypolydimethylsiloxanes (US AO 239 977), phenyltrialkoxysilanes (US AO 225 043) and additives.

Polyalkylene glycol ether (glycol brake fluids or fluids containing these components are non-prospective, their use is uneconomical because they have a short lifetime, corrode, are toxic, aggressive to the skin, and require frequent replacement for safety reasons.

The basic requirements for brake fluid are as follows:

Low viscosity over the entire operating temperature range at

100 ^DEG C min. 1.5 mm ² . s “ ¹ 40 ° C max. 900 mm ² . s ^-1 55 ° C max. 1500 mm ² .s ^-1 (for northern areas).

Low viscosity allows speed and efficiency of power transmission. With electronically controlled braking, the pressure changes up to 50 times per second. In order to obtain optimum viscosity dependence on temperature, organosilicon fluids are unsurpassed. Glycol fluids are diluted with ethanol in the northern regions to reduce viscosity, but these mixtures increase corrosion.

- Liquid stability is basically a gas bubble resistance. A gas bubble forms at the beginning of the boiling of the liquid and forces the liquid out of the pipe. It was found that with the formation of a 5 ml bubble, a critical condition occurred and with 10 ml a complete brake failure.

the lowering of the temperature at which the gas bubble is formed is due to wetting of the liquid, thermo-oxidative and hydrolytic decomposition of the liquid.

Moisture penetrates into the fluid through the fluid film, between the sleeve and the brake cylinder and through the opening in the reservoir. Since moisture enters the rollers faster than the reservoir, protecting the reservoir against moisture is not the solution.

For central regions in Europe, the lower temperature limit of gas bubble formation was set at 155 ^° C. When this temperature is reached, the fluid should be replaced immediately. The values of the onset of boiling (gas bubbles) for the liquids produced are not significant in terms of operation; the wetting rate is more important (for example, at a test at 80% relative humidity at 25 ° C, since after this test seemingly better liquids may actually be worse).

- Additional requirements for liquid properties

(a) the liquids must have a positive swellability of the rubber (0,4 to 5% on average and at the same time a reduction in hardness should be as low as possible, maximum - 15 ° Sh. Full rubber swellability is achieved at 20 ° C in 2 to 3 months;

(b) shall not corrode, as corrosive fumes ingress between the cuff and the roller cause leakage and leakage. Corroded rollers also cause leaks. The heated fluid is at a pressure of about 7 MPa or more when braking;

(c) not be toxic and aggressive to the skin.

All of the listed fluid parameters also apply to the hydraulic clutch since the fluid is common.

Until now use mostly butadiene-styrene (SBR) rubbers, which are the working temperature range of -50 C to 150 ^C, now coming into use also butadiene-acrylonitrile rubber (NBR), which are the working temperature range of -60 to 200 ° C. A liquid meeting the requirements of a prospective liquid with a long exploitation time was prepared according to AO 242 401.

A liquid has now been prepared which is cheaper to manufacture, has a higher solubility of the additives and yet satisfies all requirements. The examples given are for SBR rubber. If NBR rubber was used, the phenyltrialkoxysilanes content would increase.

The synthetic hydraulic fluid for motor vehicles at operating temperatures of -60 to 200 ° C according to the invention contains 90 to 100 parts by weight. Ω-dialkoxydimethylpolysiloxane of formula (I)

C Hj

% (M) x = 6 to 30, 0 to 10 parts by weight; phenyltrialkoxysilane as the swellability regulator of formula II

I ^C S ^H 5 (II) and the mixture formed aditlvů dioctyldiphenylamine or phenothiazine, phenyl- / 3-naphthylamine, quinizarin and dyestuffs in amounts of from 0.5 to 0.8 parts by weight.

Preferably, the α, ω-dialkoxypolydimethylsiloxanes prepared according to U.S. Pat. AO 239 977 and phenyltrialkoxysilane according to U.S. Pat. AO 225,043.

These examples illustrate embodiments of the invention.

Example 1

A 21 g flask equipped with a stirrer, a thermometer and a heating bath is charged with 900 g of dialkoxydimethylsiloxane of the formula

CHI 5

US- _{3 (3} ) C (H) -CH-1C c

CH.

with a flash point of 214 ° C, a pour point below - 70 ° C, a viscosity at 100 ° C of 10,6 mm ² . s ^-1 , at —40 ° C 251 mm ² . with ¹ and at -60 ° C 723 mm ² .s ^-1 , and 100 g of phenyltri (2-ethylhexoxy) silane with a flash point of 198 ° C, a pour point below -70 ° C, a viscosity of 100 ° C of 2.53 mm ² .si, at 40 ° C 879 mm ² .s ^-1 and with stirring and heating the flask up to 100 ° C, a mixture of additives consisting of 4.5 g of dioctyldiphenylamine, 0.60 g of phenyl -? - naphthylamine was added, 0.15 g quinizarin, 0.10 g Solvent Red 25-26110 (Cl). Within about 0.5 hours, the mixture was homogenized and then the contents of the flask were filtered through filter paper. The liquid obtained was clear, red colored. Treatment liquid on butadiene-styrene rubber cuff ^P at 120 C for 70 h. To expand its diameter by 2.09% and a decrease in hardness was -5 ° Sh.

CH.

i 3

ROi-SbO). -CH.1 t ^Ch 3

The weight gain of the liquid at 80% relative humidity at 20 ° C was 0.1% at 90 hours and practically did not change further. The gas bubble did not form at 250 ° C after wetting. The wetted liquid at -55 ° C remained homogeneous.

The liquid was subjected to a corrosive oxidation air bubbling test at 175 ^° C for 72 hours in the presence of copper, steel, aluminum and magnesium alloys. After this test, the liquid was clear, free of deposits, and practically did not corrode.

Example 2

The brake fluid was prepared in the same manner and on the same apparatus as in Example 1 of 940 g

CH-f CH 2 Cl ₅ with a flash point of 197 ° C, a pour point below -70 ° C, a viscosity at 100 ^° C of 3.66 mm ² . st, at –40 ° C 91 mm ² . s ^-1 , at -60 ° C 318 mm ² . with ^_1, followed by 60 g C6H5Si (OR) 3 wherein R is 2-ethylhexyl, and the same amounts of additives as in Example 1. When applying the cuff to increase the diameter about 0.69% and the hardness change was -3 ° Sh.

Example 1 a d 3

In the same manner and on the same apparatus as in Example 1, a liquid of 1000 g was produced

C Hx ⁵

RO-S-O) _r-CH = CH- (CH _i) y ^CH 3 ^C ₅ ^H 5-d with a flash point of 184 ° C and a freezing point below -70 ° C, a viscosity at 100 ^DEG C, 2.30 mm ^2nd s ^-1 , at —40 ° C 61 mm ² . s ^-1 , at -60 ^° C 238 mm. with ^2-1 and the same amount of additives as in Example 1. Upon exposure to the cuffs, the diameter increased by 1.5% and the hardness change was 66 ° Sh.

Example 4

In the same manner and on the same apparatus as in Example 1, a liquid of 920 g was produced

CH. I ³

CH _d with flash point 230 ° C, pour point below -70 ° C, viscosity at 100 ° C 7.23 mm ² . . s ^-1 at 40 ° C 165 mm ² .s ^_1, at -60 ° C 516 mm ^ s' ^1, followed by 80 g CeHsSifORjs wherein R is 2-ethylhexyl, and the same amounts of additives as in Example 1. In the effect on the cuffs increased by 2.0% and the hardness change was —5 ° Sh.

All liquids are non-toxic, harmless to the eyes, very harmful to the skin. The fluids are suitable for all areas of the world as they meet all the requirements for brake fluid. The swellability of the rubbers can be controlled over the entire desired range. Iro corrosion and stability can be expected very long liquid exploitation time while maintaining safety requirements. The long exploitation time is of great economic benefit because the average life of cars is about 20 years and with continuous improvement it can be expected even longer.

Subject

Claims (1)

VYNALEZU Synthetic hydraulic fluid for motor vehicles for operating temperatures from -60 to 200 ° C, characterized in that it contains 90 to 100 parts by weight α, ω-dialkoxypolymethylsiloxanes of formula I RO- (SiO) ^ CH ^ · CH _b CH x (CH ₂ ) ₅ 'CH ₃ wherein x = 6 to 30, the phenyltrialkoxysilane of formula II as a swellable regulator, in an amount of up to 10 parts by weight; CeH5Si (OR) 3 (II) wherein R is 2-ethylhexyl and a mixture of additives consisting of dioctyldiphenylamine or phenothiazine, phenyl-, 8-naphthylamine, quinizarin and dye in an amount of 0.5 to 0.8 parts by weight.