Manufacturing method of polyvinyl butyral film

The invention discloses a manufacturing method of a polyvinyl butyral film. The manufacturing method is characterized by comprising the following steps: pretreating polyvinyl alcohol and n-butanal raw materials to reduce impurities in the raw materials; then performing a condensation reaction, and performing washing and solvent soaking on generated polyvinyl butyral resin after the reaction to remove side reactions generated by the condensation reaction and residual impurities; and finally, performing heating melt plasticization and tape casting on the dried polyvinyl butyral resin together with a plasticizer, an antioxidant and an auxiliary agent in an extruding machine, thereby obtaining the polyvinyl butyral film. According to the manufacturing method disclosed by the invention, by reducing the impurities in the raw materials, the polyvinyl butyral resin with relatively high transparency is obtained, and by adding the antioxidant and the auxiliary agent, the polyvinyl butyral film can avoid aging discolora