| Brake fluid is a working medium of braking power transmission.Although the brake fluid has formed production market under the normal temperature environment, the performance of the high-heat-cold-resistant boric ester brake fluid does not reach the standard , e.g. it is easy to produce air-resistance at high temperature and its mobility become bad at low temperature,which will make the pressure transmission poor and then affect the driving safety. It is particularly important for the traffic safety under the high temperature and cold regions.In the paper, a high-heat-cold-resistant boric ester brake fluid was produced in order to solve the following problems, including bad high-low temperature performance, instability of acid hydrolysis and poor corrosion resistance etc. In the procedure of this brake fluid, a three-step synthesis method was adopted, and use alcohol and propylene as raw materials. The reaction principle of this method was using small molecules chain alcohol and propylene oxide reacting in the base of catalyst under high pressure, easily generating the main ingredients 3 or 4 poly alcohol ether.In the paper, firstly the effect of different materials on the synthesis of polyether was studied firstly, and two kinds of propylene oxide polyether based on butanol and propanol were synthesized. The obtained propylene oxide poly ether-propanol was slightly yellow transparent liquid, and had no sediment formation, its boiling point being up to 240℃.Two kinds of propylene oxide polyether based on propanol and methanol were synthesized, and the effect of reaction temperature and pressure on the synthesis of polyether was studied. The optimal reation temperature for synthesizing propylene oxide poly ether-propanol and propylene oxide poly ether-methanol were 170℃～190℃and 190℃～210℃, respectively.The obtained poly ether- propanol and poly ether-methanol reacted with boric acid separately, and two kinds of poly-ether boric acid ester based on propanol and methanol were obtained. The optimal conditions for poly ether-propanol boric acid ester were as follows: m(boric acid ester):m(poly ether-propanol)=1:28, reaction temperature 130℃, reaction time 3 hours. Under theses conditions, and the yield of poly ether-propanol boric acid ester was up to 94%. The optimal conditions for poly ether-methanol boric acid ester were as follows: m(boric acid ester) : m(poly ether-methanol)=1:26, reaction temperature 130℃, reaction time 3 hours, and the yield of poly ether-propanol boric acid ester was 93%.The structures of the synthetic products was analyzed by IR. Using the obtained poly ether and boric acid ester as main materials and adding some addictives, a high-performance boric acid ester brake fluid was prepared and the corrosion-resistant effect of different preservatives on the brake fluid was also studied. Finally, the performance test results demonstrated that the brake fluid reached the standard of American DOT-4. |
