Study On Synthesis Technics Of High Viscosity Polyvinyl Butyral Resin For Laminated Safty Glass

High viscosity polyvinyl butyral (PVB) is the essential material for laminated safety glass because of its excellent adhesion and optical properties. With the rapid development of economy, there was a sharp rise in demand of PVB. But the resin made in China had low viscosity, low acetalization rate and low diaphaneity, which could not reach the requirements of laminated safety glass.First, this paper will discuss the determination method of acetalization rate. There are some main problems involved in. For example, the calculation formula is unclear and it is difficult to accurately judge the endpoint with indicator in acid base titration. In the research, the methyl orange was used as indicator. A novel calculation formula was proposed according to the definition of acetalization. The results showed that the relative standard deviation of the acetalization rate was0.33%in parallel experiments.Second, a new synthesis technique of high viscosity PVB resin synthesized in the water/isopropanol system will be presented in this paper. Some craft parameters as reaction temperature, reaction time, material proportion were optimized. The results showed that the obtained optimum condition of solvent was V (water):V (isopropanol)=175:25. In this condition, the synthesized resin not only had high acetalization rate and uniform distribution of aldehyde acetal group, but also had the advantages of high yield and easy to clean. Using the plasticizer of triethylene glycol bis(2-ethylhexanoate)(3GO) for the performance test of the obtained PVB film. The effects of the amount of3GO were studied by the data of tensile strength, breaking elongation, Tg and melt flow rate. The results showed that the comprehensive properties were the best when the PVB film with30%3GO. In addition, it was found that choosing an optimum molecular weight PVB resin is an important factor to prepare the high property PVB film through the comparison of structure and properties of PVB resin.Finally, in order to improve the processing property of PVB resin, using ethanol as solvent and TEOS as crosslinker, the branched PVB resin was synthesized by dissolution process. The results showed that the viscosity of crosslinked solution was780mPa·s,1220mPa·s lower than that without crosslinker. Therefore, it is an effective method to reduce viscosity of PVB resin.