BRAKING LIQUID AND METHOD OF PREPARING THEREOF

FIELD: chemical industry. SUBSTANCE: liquid comprises boric acid esters and polyethylene glycol monoalkyl ethers of formula I: B[O(CHR2CH2O)R3 wherein R is CH3 or C2H5; R2 is H or CH3; n is integer of 3 to 6; polyalkylene glycol monoalkyl ethers of general formula II: R1(CH2CHR2)mOH wherein R1 is C3-C5 radical; R2 is H or CH3; m is integer of 2-3; buffer component based on alkali metal borate, antioxidizing and anticorrosion addition agents such as diphenyl propane, tolyl triazole, benzotriazole, the ratio of components is the following, wt.%: compound of general formula I, 40-89; compounds of general formula II, 10-54; buffer component, 0.5-5.0; anticorrosion addition agent, 0.01-0.2; and antioxidizing addition agent, 0.05-0.2. Braking liquid is prepared by reacting ethylene oxide of formula: with methyl or ethyl alcohol in the presence of alkaline catalyst. After oxyalkylation of alcohol, low molecular weight components are distilled from the resulting mixture of glycol ethers, remaining mixture of polyalkylene methyl or ethyl ethers are reacted with boron-containing reagent. After distillation of low- boiling components, the resulting borate is mixed with compounds of general formula II. Boron-containing reagent includes boric acid, boric anhydride or trimethyl borate. The claimed has improved compatability with rubber and its all parameters correspond to international standard USS 116a, Class DOT-4. EFFECT: improved properties of the braking liquid. 5 cl, 1 tble