Aromatic copolyamides, processes for their preparation and structures formed therefrom

An aromatic copolyamide which is soluble in organic polyamide solvents and contains the recurring structural units of the formulae Ia, Ib, Ic and Id

• [--OC--R.sup.1 --CO--NH--R.sup.2 --NH--] (Ia),
• [--OC--R.sup.1 --CO--NH--R.sup.3 --NH--] (Ib),
• [--OC--R.sup.1 --CO--NH--R.sup.4 --NH--] (Ic),
• [--OC--R.sup.1 --CO--NH--R.sup.5 --NH--] (Id),
• in which 90 to 100 mol % of all radicals R.sup.1, with respect to the amount of these radicals in the copolymer, are a divalent aromatic radical, the valency bonds of which are in the para-position or in a comparable coaxial or parallel position with respect to one another, and which is unsubstituted or substituted by one or two inert radicals, and 0 to 10 mol % of all radicals R.sup.1, with respect to the amount of these radicals in the copolymer, are a divalent aromatic radical, the valency bonds of which are in the meta-position or in a comparable angled position with respect to one another, and which is unsubstituted or substituted by one or two inert radicals,
• R.sup.2 is a divalent aromatic radical, the valency bonds of which are in the para-position or in a comparable coaxial or parallel position with respect to one another, and which is unsubstituted or substituted by one or two inert radicals, and
• R.sup.3 is a radical of the formula II ##STR6## R.sup.4 is a radical of the formula III
• --Ar.sup.1 --O--Ar.sup.1 --O--Ar.sup.1 -- (III), and
• R.sup.5 is a radical of the formula IV or V or a combination thereof ##STR7## in which Ar.sup.1 has one of the meanings defined for R.sup.2, Y is hydrogen, a halogen atom, a lower alkyl group or a lower alkoxy group, X is a halogen atom, a lower alkyl group or a lower alkoxy group, and the proportion of recurring structural units Ia, Ib, Ic and Id, with respect to the sum of these structural units in the copolymer, is within the following limits:
• recurring structural unit of the formula Ia:
• 30 to 70 mol %;
• recurring structural unit of the formula Ib:
• 15 to 40 mol %;
• recurring structural unit of the formula Ic:
• 5 to 30 mol %;
• and
• recurring structural unit of the formula Id:
• 5 to 30 mol %.