Patent ID: 8349971
Filing Date: 2013-01-08
Classification: C08G,C08L

Abstract:
1. A process for preparing a cyclized/crosslinked polyimide copolymer produced by a three-step polymerization reaction consisting essentially of (i) mixing and heating 1 molar equivalent of 1,4-bis(3,5-diaminobenzoyl) piperazine (BDP), 4 molar equivalents of biphenyltetracarboxylic dianhydride (BPDA) and 4 molar equivalents of diaminodiphenyl ether (DADE) at 160-200° C. in the presence of a catalyst in an organic polar solvent, to produce product (1), (ii) adding 8 molar equivalents of pyromellitic dianhydride (PMDA) and 4 molar equivalents of diaminotoluene (DAT) to product (1) and heating them to produce product (2), and (iii) (a) adding 2 molar equivalents of BPDA and 4 molar equivalents of DAT, or (b) adding 2 molar equivalents of diaminosiloxane, to product (2) and heating them.