GB1354926A - Polyimides - Google Patents

Abstract

1354926 Copolyimides UPJOHN CO 23 Sept 1971 [25 Sept 1970 16 March 1971] 44462/71 Heading C3R A copolyimide (I) has recurring unit (U) where in 10-90% of (U), R is and in the remainder of (U), R is and/or (I) may be made by reacting benzophenone- 3,3<SP>1</SP>,4,4<SP>1</SP> - tetracarboxylic acid dianhydride with a mixture of bis-(4-aminophenyl) methane and 2,4- and/or 2,6-toluenediamine, or by reacting the anhydride first with one diamine and then with the other(s), yielding the corresponding polyamic acid (A) The reaction may be performed in an inert organic solvent (S) at from below 50‹ C. to up to 175‹ C. in anhydrous conditions (A) is usually formed in solution in solvent (S), and may be isolated, e.g. by evaporating (S) or adding a non-solvent. (A) may then be cyclized to (I) by thermal treatment or by treatment with an acid anhydride, preferably in the presence of a tertiary amine, at #200‹ C. Or (I) may be made from the tetracarboxylic acid dianhydride and 4,4<SP>1 </SP>- methylenebis(phenyl isocyanate) and toluene 2,4- and/or 2,6-di-isocyanate, in a dipolar aprotic solvent, at from ambient temperature up to 160‹ C. The di-isocyanates may be mixed before the dianhydride is added, or the toluene di-isocyanate may be first reacted with the dianhydride, followed by addition of the other di-isocyanate. Co. polyimide (I) may then separate as a solid from the reaction mixture, or, if the proportion of units derived from toluene di-isocyanate is #70%, (I) may remain in solution, and may be precipitated therefrom by adding a non-solvent for (I). Uses.-(I) may be moulded by sintering or hot pressing to form sheets, bushings, seal-faces, electric insulators, compressor-valves and impellers, pistons and piston-rings, gears, threadguides, cams, brake-linings, clutch-faces, or abrasive articles, e.g. grinding-wheels. Specication 1,354,927 is referred to.