Process for the production of polyamide-polyamide-acid copolymers

Claim 1

A process for preparing a polyamide/polyamide-acid copolymer having an inherent viscosity of 0.1 to 2.5 or the derivative cyclized to the corresponding polyamide-polyimide copolymer, which comprises (i) reacting a polyamide-acid having an average molecular weight of 750 to 20,000 of formula I ##STR9## with a diamine of formula II H.sub.2 N--R.sub.2 --NH.sub.2 and with a dicarboxylic acid dichloride of formula III ##STR10## in a molar ratio of 1 to a to a-1, or reacting a polyamide-acid having an average molecular weight of 750 to 20,000, of formula IV ##STR11## with a dicarboxylic acid dichloride of formula III and with a diamine of formula II, in a molar ratio of 1 to a to a-1, in which formulae I to IV a represents an integer from 8 to 100, and b represents an integer from 2 to 100, with the proviso that, when b represents an integer from 8 to 100, a represents an integer at least equal to b, R 2 and R 4 independently of one another denote a monocyclic aromatic radical which may be substituted by alkyl or alkoxy groups each having 1 to 4 carbon atoms, or an uncondensed bicyclic aromatic radical which may be substituted by alkyl or alkoxy groups each having 1 to 4 carbon atoms, and in which the aromatic nuclei are bonded to one another through the bridging member --O-- or --CH 2 --; R 1 denotes an unsubstituted monocyclic aromatic radical, with the carbonyl groups being bonded to different carbon atoms; and R 3 represents an unsubstituted monocyclic, a condensed polycyclic or an uncondensed bicyclic aromatic radical in which bicyclic aromatic radical the aromatic nuclei are bonded to one another through the bridging member --O-- or --CO--, wherein the carbonyl and carboxyl groups are bonded to different ring carbon atoms and adjoin each other in pairs and the carbonyl groups of the anhydride end groups are located on adjacent ring carbon atoms, in an anhydrous organic aprotic solvent or a mixture of such solvents, with the exclusion of moisture, at temperatures between about -20° C. and +50° C., and (ii) optionally cyclizing the polyamide/polyamide-acid copolymer obtained by heating to temperatures between about 100 and 300° C., or by treatment with a dehydrating agent by itself or mixed with a tertiary amine.