Process for preparing polyimide and composite material thereof.

摘要

This invention relates to a method for preparing polyimide having good heat-stability and excellent flowability in a molten state. The polymide is prepared by reacting aromatic diamines such as 4,4 min -bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl] ketone and bis [4-(3-aminophenoxy)phenyl] sulfone; tetracarboxylic dianhydrides such as pyromellitic dianhydride, 3,3 min ,4,4 min -benzophenonetetracarboxylic dianhydride and bis(3,4-dicarboxyphenyl) ether dianhydride; and monoamines such as n-hexylamine, cyclohexylamine, aniline, 4-aminobenzophenone. The molar ratio of tetracarboxylic dianhydride : aromatic diamine : monoamine is 1:(0.9 to 1.0):(0.001 to 1.0). Another invention relates to polyimide composite materials which are excellent in mechanical strengths and processability. The materials contain the polyimide above prepared and fibrous reinforcing materials such as yarn, roving, tow, fabrics, mats and felts of glass fiber, carbon fibers or aromatic polyamide fibers.