MODIFIED POLYVINYL BUTYRAL AND METHOD FOR ITS PRODUCTION Russian patent published in 1997 - IPC

FIELD: plasticized thermal plastic molding mixtures. SUBSTANCE: polyvinyl butyral on the base of polymer of vinyl alcohol with glyoxal-bis-acryl amide is prepared by copolymerization of vinyl acetate with 0.01-1.0 mol % of glyoxal-bis-acryl amide (as calculated for total molar amount of comonomers). Thus prepared copolymers have complex viscosity of the melt (3-10,1)10³ (being determined in vibration rheometer at 180 C at frequency 10^-1s^-1). Then copolymers are affected by alkali hydrolysis to prepare rarely cross-linked copolymer of vinyl alcohol with glyoxal-bis-acryl amide, the process is carried out till degree of hydrolysis is 95-99.5 mol %. Copolymer is treated by butyraldehyde to prepare modified polyvinylbutyral which comprises 15-18 mass % of vinyl alcohol units, complex viscosity of its melt being /3,8-8,3/^o10³ (being determined in vibration rheometer at 200 C at frequency 10^-1s^-1). Proposed method involves production of origin copolymer of vinyl acetate with glyoxal-bis-acryl amide, alkali hydrolysis thus prepared copolymer in aqueous-methanol solution, the process is carried out till degree of hydrolysis is 95-99.5 mol %. Then hydrolyzed rarely cross-linked copolymer of vinyl alcohol with glyoxal-bis-acryl amide is treated by butyraldehyde, the process is carried out in aqueous medium in the presence of acid catalyst. EFFECT: improved quality. 5 cl, 4 tbl