Preparation method of polyvinyl butyral resin

The invention discloses a preparation method of polyvinyl butyral resin. The raw materials includes: polyvinyl alcohol, butyraldehyde, an acidic catalyst and water, and also includes polyvinyl butyral. According to the invention, the raw material polyvinyl butyral particles with a high acetalization rate are used as a condensation core to replace primary PVB, compared with the prior art, the method has the advantages that primary PVB is replaced, the acetalization rate of finished PVB can be remarkably increased, and due to the existence of polyvinyl butyral particles serving as raw materialsin a reaction system, extension of a polyvinyl alcohol molecular chain is facilitated, the stability of acetalization reaction is improved, and the distribution of acetal groups of the product is improved to a certain extent. 本发明公开了一种聚乙烯醇缩丁醛树脂的制备方法，其原料除包括聚乙烯醇、丁醛、酸性催化剂和水外，还包含聚乙烯醇缩丁醛。本发明使用高缩醛率的原料聚乙烯醇缩丁醛颗粒作为凝聚核心，替代初生的PVB，可显著提升成品PVB的缩醛率，又因为反应体系中有原料聚乙烯醇缩丁醛颗粒的存在，有利于聚乙烯醇分子链的舒展，提高缩醛反应的稳定性，一定程度上改善产品缩醛基的分布。