SOLUTION COMPOSITIONS OF BLOCK COPOLYIMIDES COMPRISING PYROMELLITIC DIANHYDRIDE AND PROCESS FOR PRODUCTION THEREOF

摘要

In general, polyimides prepared from PMDA and aromatic diamines are little soluble in solvents. The invention aims at making such polyimides soluble in solvents and producing at least quaternary block copolymers. An oligomer soluble in solvents can be produced by reacting PMDA with a specific aromatic diamine at a mole ratio ranging from 1 : 1.5 to 1 : 2, and an at least quaternary block copolymer soluble in solvents can be produced by further adding an acid dianhydride and an aromatic diamine to the system. The mole ratio of PMDA to the aromatic diamine to be added together with PMDA lies between 1 : 1.5 and 1 : 2. Thus, many PMDA-comprising block copolymers soluble in solvents can be produced. At least quaternary block copolyimides comprising PMDA, BTDA and DAT can be produced by successive polymerization in the presence of a binary catalyst, which enables the production of various polyimides from various inexpensive and easily available raw materials. Employment of direct imidation excellent in economical efficiency enables low-cost mass production of high-performance polyimides comprising PMDA, BTDA and DAT, thus bringing about wide application of the polyimides.