Preparation method for high-grade borate type brake fluid

Abstract

The invention relates to a preparation method for a high-grade borate type brake fluid, comprising the steps of synthesis for polyol ethers, a synthesis for borates, and a blending for a brake fluid. Glycerol monomethyl ether and tetrapropanol monomethyl ether are mainly obtained under the catalysis of an alkaline-earth metal catalyst by using methanol and epoxy propane as raw materials, and the polyol ethers having other molecular weights are few; cyclic and branched borates are synthesised by using boric acid, polyol ethers and ethanediol as raw materials; and a high-grade borate type brake fluid is blended by using the borates as base fluids, using the polyol ethers as diluents, and adding proper additives. The preparation method for a high-grade borate type brake fluid disclosed by the invention is low in cost, safe and reliable; improves the high-temperature air blockage resistance and low-temperature flowability of the brake fluid; and obviously improves the performances due to the generated cyclic borates in the aspects of boiling point and hydrolysis stability particularly.

Description

Technical field [0001] The invention relates to a method for preparing a hydraulic brake medium for a motor vehicle, in particular to a method for preparing a high-grade borate ester brake fluid. Background technique [0002] Automobile brake fluid is the working medium that transmits pressure in hydraulic transmission and affects the braking control of automobiles. Since automobiles began to use brake fluid in the early 1930s, the development of brake fluid has gone through three types, namely ricinoleol Type, mineral oil type and synthetic type, alcohol type brake fluid and mineral oil type brake fluid have long been eliminated due to their low boiling point and high freezing point, and synthetic brake fluid was produced. The synthesis process of alcohol ether synthetic brake fluid is simple, and the product has good lubrication performance, but its water resistance is poor, which causes the equilibrium reflux boiling point of the brake fluid itself to decrease, the low-te...

AI Technical Summary

Problems solved by technology

This method does not consider how to deal with the moisture produced by the reaction, the impact of high temperature reaction on the performance of additives and the hydrolysis stability of boric acid ester, and the content of boric anhydride used is too high as 20-30%, which not only increases the cost, but also the boric anhydride is too high. Easy to form polymers, high borate content, easy to hydrolyze

In addition, the antioxidant diethylene glycol alkyl ether used lacks sufficient antioxidant capacity, and the preservative propylene oxide or ammonium sulfonate does not fully consider the corrosion resistance of metals.

[0006] In 2003, the patent CN1544591A used diethylene glycol and boric anhydride to prepare boric acid ester, and the brake fluid can only meet the requirements of DOT3 level indicators

[0007] The 2008 patent CN101418249A uses alcohol ether borate and polyalcohol ether at a ratio of 5:1, which increases the cost of brake fluid. In addition, if the content of borate is too high, boric acid is easily hydrolyzed. The additive is too simple, not as good as those synergistic The additives have good effects in anti-corrosion, anti-oxidation, etc.

[0008] The 2009 patent CN101486943A uses acid as a catalyst, the reaction time is relatively long, there are many by-products, and the equipment is corroded

In addition, only 4 kinds of additives are used in the preparation of brake fluid, and the problems of rubber swelling, anti-rubber shrinkage, and hydrolysis stability of the brake fluid are not considered, and the effects of anti-corrosion and anti-oxidation are not very good.

[0009] In 2009, the patent CN101619258A used sodium hydroxide as a catalyst, which reacted quickly and had no by-products, but the molecular weight distribution of the polyol ether produced was wide, and the monoether of monopropanol and dipropanol accounted for 35% to 45% of the total, and it was not separated Come out, the boiling point of the synthesized boric acid ester is lower than that of only tri- and tetrapropanol monoether. To improve the hydrolytic stability of the brake fluid, it can only be realized by adding a hydrolytic stabilizer. The hydrolytic stability is improved to a certain extent, but it is not enough ideal

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