RU2078121C1 - Braking liquid - Google Patents

Abstract

FIELD: production of braking liquids. SUBSTANCE: liquid comprises 25-50 % of monoethyl ether of triethylene glycol, 5-15 % of polypropylene glycol having molecular weight 400-1000, 20-40 % of esters of boric acid on the base of mixture of monoethyl ether of triethylene glycol and monobutyl ether of diethylene glycol at their ratio 1:1 respectively, 1-5 % of peptizing agent, 0.1-1.0 % of antioxidant additive, 0.3-1.5 % of anticorrosion additive and monoethyl ether of diethylene glycol. EFFECT: improved quality. 3 tbl

Description

 The invention relates to the chemistry of hydraulic fluids, and in particular to compositions of brake fluids used in hydraulic brakes and clutches of automobiles.

 The modern level of automotive technology makes high demands on brake fluids used in hydraulic brakes. Depending on the climatic operating conditions of automotive vehicles, in accordance with the standards of the Society of Automotive Engineers SAE J 1702 and SAE J 1703, the most important indicators are distinguished from a wide range of physicochemical properties of brake fluids, which are responsible for ensuring the reliability of the vehicle's brake system in specific conditions operation. Such indicators are given in table 1.

 For example, according to SAE J 1703 (normal climatic conditions), the most important indicators are the high boiling point of dry and moistened liquids and setting the viscosity-temperature curve over a wide temperature range.

 Brake fluids are known, in particular, containing glycol alkyl esters and boric acid esters based on glycols and their derivatives, which provide the necessary values of such indicators as the boiling point of dry and moistened liquids (1).

 The disadvantage of such compositions is that the latter have increased viscosity values at low temperatures, which complicates their use at low temperatures, for example, in the Far North. In this regard, the requirements of the standard SAE J 1702 can be satisfied by the introduction of additives in the brake fluid, which can improve the low-temperature properties of the brake fluid.

Thus, brake fluid is known containing about 50 wt. diethylene glycol monoethyl ether, 31 wt. polypropylene glycol with a molecular weight (MM) of 1000, 20 wt. boric esters based on a mixture of diethylene glycol and triethylene glycol monoethyl ether [2]
The specified composition has a boiling point of dry liquid 205 - 210 ^o C, the boiling point of humidified liquid 140 142 ^o C and, accordingly, meets the requirements of standard SAE 1703 class DOT-3.

 The disadvantage of the brake fluid in accordance with [2] is the high viscosity at low temperatures, which is apparently due to the viscosity-temperature properties of its base (50 wt.% Diethylene glycol monoethyl ether). This drawback limits the use of this brake fluid in the Far North and other regions with harsh winters.

 The aim of the invention is to provide a brake fluid having high boiling points of dry and moistened fluids and ensuring uninterrupted operation of the brakes at low temperatures, for example, in the Far North and other regions with harsh winters.

 To achieve this, the invention provides a brake fluid containing monoethyl esters of di- and tri-ethylene glycols, polypropylene glycol with a molecular weight of 400 to 1000, boric acid esters based on a mixture of triethylene glycol monoethyl ether and diethylene glycol monobutyl ether, a plasticizer, an antioxidant and antioxidant the following components, wt.

Triethylene glycol monoethyl ether 25.0 50.0
Polypropylene glycol with a molecular weight of 400 1000 5.0 15.0
Boric acid esters based on a mixture of triethylene glycol monoethyl ether and diethylene glycol monobutyl ether 20.0 40.0
Plasticizer 1.0 5.0
Antioxidant Additive 0.1 1.0
Corrosion inhibitor 0.3 1.5
Diethylene glycol monoethyl ether Up to 100
Triethylene glycol monoethyl ether, included in the brake fluid formulation, is a light yellow hygroscopic fluid. This ether is well soluble in water, alcohol, glycols. At 20 ^o C its density is 1.01 g / cm ³ , boiling point at 760 torr. 240 ^o C, pour point (-44) ^o C.

Polypropylene glycol with MM 400 1000 used in the brake fluid formulation is prepared by reacting propylene oxide with propylene glycol in the presence of an alkali metal hydroxide under a pressure (P) of 0.29 0.35 MPa and a temperature of (T) of 100 130 ^o C. Depending on the amount of spent propylene oxide MM obtained the adduct ranges from 400 to 1000. In this interval, the functionally important properties of the thickener do not undergo noticeable changes. The synthesis product is then neutralized with phosphoric acid and at (P) 50 100 torr. and T = 80-100 ^° C., water is distilled off. The product is separated by filtration from the precipitate. Obtained in accordance with the described technology polypropylene glycol with MM 400 1000 has the following characteristics: hydroxyl number 3.4 to 6.8 wt. kinematic viscosity at 25 ^o C, 80 130 cSt, pour point below (-40) ^o C.

The above boric acid esters based on a mixture of triethylene glycol monoethyl ether and diethylene glycol monobutyl ether (oligofirborates) are obtained by dissolving boric acid in the above mixture (mass ratio of ethers 1: 1), followed by distillation of water from the reaction mass. The resulting oligoborate is a light yellow liquid, readily soluble in alcohol; its kinematic viscosity at (+50) ^o C is 6 6.5 cSt, the boiling point at a pressure of 760 torr. not lower than 302 ^o C, pour point (-60) ^o C and below, boric acid content of 10.8 to 11 wt.

 Introduction to the composition of the plasticizer ensures the preservation of the operational characteristics of the rubber parts of the brake system. In this regard, it is advisable to use a plasticizer that is the same as the equilibrium amount contained in the rubber (i.e., it does not cause either excessive swelling of the rubber or excessive embrittlement of the rubber due to absorption of excess or loss of the amount of plasticizer, respectively). Usually, LZ-EK ester (diethylene glycol monoethyl ester of fatty acids of the C2-C5 fraction) or dioctyl adipate (GOST 8728-84) are used as a plasticizer.

 As an antioxidant additive, it is advisable to use diphenylolpropane or ionol.

 Protection of metals from corrosion under the influence of moisture and brake fluid is ensured by the introduction of an anti-corrosion additive, for example, a mixture of benzotriazole and morpholine, into the brake fluid. You can use other anti-corrosion additives known from the prior art.

 Diethylene glycol monoethyl ether used in the preparation of brake fluid is produced by the industry in accordance with the requirements of TU 6-01-5757583-6-89 with a basic substance content of at least 95.0 wt.

 The following examples illustrate some of the possible embodiments of the invention. Assessment of the physico-chemical properties of the brake fluid is carried out according to the method ТН 6-01-1276-82, adopted for the Tom brake fluid.

Example. Samples of brake fluid are prepared in a 5.0 L metal reactor by mixing the liquid components at 60 ^° -70 ^° C., followed by dissolving the solid reagents in the liquid phase. The calculated amounts of reagents are loaded into the reactor and the resulting mass is stirred at 70 ^° C. until the components are completely dissolved. Then the resulting product is filtered.

 The formulation of the obtained liquid samples are given in table 2, and their physico-chemical properties in table 3.

 The data table. 2 and 3 show that the introduction of the above oligoetherborates into the brake fluid formulation improves the low temperature properties and increases the boiling point. Increasing the concentration of oligoegoesterborates in the formulation to values over 45 wt. or below 20 wt. leads to deterioration in low temperature properties.

 Samples of brake fluids in accordance with the invention are characterized by higher boiling points of dry and moistened fluids with improved low temperature characteristics, which expands the possibility of using this fluid in changing temperature conditions, i.e. provides a new technical result.

 The following example illustrates some of the possible embodiments of the invention, but does not limit its scope, defined exclusively by the following claims.

INFORMATION SOURCES
1. US patent N 3711412, CL. C 10 M 3/48, 1973.

 2. Khavrova L.E. and others. Protection of glycol brake fluids from water. Chemistry and technology of fuels and oils, 1983, N 11, p. 21-22.

Claims (1)

 Brake fluid containing monoethyl esters of di- and triethylene glycols, polypropylene glycol with a mol.m. 400 1000, esters of boric acid and monoalkyl esters of glycols, a plasticizer, antioxidant and anticorrosion additives, characterized in that the liquid additionally contains triethylene glycol monoethyl ether, and boric acid esters contains boric esters based on a mixture of triethylene glycol monoethyl ether and monobutyl ether a mass ratio of 1 to 1 with the following content of components, wt. Triethylene glycol monoethyl ether 25.0 50.0
Polypropylene glycol with a mol.m. 400 1000 5.0 15.0
Boric acid esters based on a mixture of triethylene glycol monoethyl ether and diethylene glycol monobutyl ether 20.0 40.0
Plasticizer 1.0 5.0
Antioxidant Additive 0.1 1.0
Corrosion inhibitor 0.3 1.5
Diethylene glycol monoethyl ether Up to 100n

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