A Study On Polyvinyl Butyral’s Semi-continuous Production Equipment And Technology

Polyvinyl butyral (PVB), which, at present, is widely used in automobile, architecture, aerospace, military and other fields, is a newly synthetic resin with outstanding optical property, mechanical property and property of adhering many materials. In recent years, with the rapid development of these fields, PVB’s market demand is also increasing rapidly. However, the production technology of PVB has the shortcomings like intermittent of production mode, low productivity and major quality fluctuation between different batches, which on some extent have limited the development of PVB industry.This paper firstly analysis several batch production methods of PVB, and decides to synthesize PVB by the way of precipitation. Then by means of analyzing and comparing the characteristics of pipe reactor and tank reactor, it explores PVB’s continuous production technology, but due to the adhesive property of PVB, the pipe reactor method failed. The biggest problem of the continuous stirred tank reactor (CSTR) is the back-mixing behaviour. By using a double paddle stirrer and controlling its speed within a suitable range, the materials mixes mainly in the radial direction, so the influence of back-mixing on acetalization can be reduced as much as possible.By using the CSTR, the preliminary product could be produced continuously.The study also discusses factors that affect the quality of product, and gets the best reaction condition, which is:mass ratio of PVA and butyraldehyde is5:3; feeding speed of PVA/BA liquid mixture (V1) is40mL/min, and that of hydrochloric acid (V2) is1.2mL/min (showing a ratio of100:3); initial reaction temperature is10℃, reaction time is2h, heating rate is5℃/20min, high temperature reaction at65℃for2h. The results show that the degree of acetalization of the synthesized PVB product under this condition may attain to78.2%. FT-IR and1H-NMR are used to characterize the structure of PVB product. The product’s molecular weight and solubility test prove that synthesized PVB products have reached the industrial standards.