High molecular weight polyvinylbutyral, for production of laminated safety glass, comprises use of benzofuran and/or at least one derivative as crosslinking agent

摘要

High molecular polyvinylbutyral is obtained with good reproducibility by crosslinking of polyvinylbutyral using benzofuranone and/or at least one derivative as crosslinking agent. High molecular polyvinylbutyral is obtained with good reproducibility by crosslinking of polyvinylbutyral (PVB) using benzofuranone and/or at least one derivative as crosslinking agent. The crosslinking agent comprises compounds of formula (I). Ra, Rb, Rd, Re, Rf, Rg and Rh = H, OH, 1-18C alkyl, unsubstituted or mono-, di, or tri-substituted phenyl substituted by 1-4C alkyl, 7-9C phenylalkyl, unsubstituted or 1-4 C alkyl substituted mono-,di,- or tri 5-12C cycloalkyl or 1-18C alkoxy; Rc = one of the above Ra-Rh series, or a residue of formula (II), where the series; and Ri and Rj = H, or 1-4C alkyl, where at least two of Rd-Rh = H. Independent claims are also included for the following: (i) preparation of PVB with the addition of the above crosslinking agent and optionally a plasticizer to the PVB, homogenization of the mixture, and thermal crosslinking at 80-280 deg C; (ii) a molding composition comprising PVB; and (iii) a film comprising the PVB.