Fluid shapable sulfuric compositions based on arylaliphatic copolymers

Claim 1

A fluid, shapable, sulphuric composition which is optically anisotropic at temperatures below 100° C., consisting essentially of a sulphuric solvent and a solute which consists essentially of a copolyamide with a fiber forming inherent viscosity of at least 1 when measured on a solution in substantially pure sulphuric acid at 25° C. and at a concentration of 0.5 g of polymer in 100 ml of solution, consisting of units selected from the group consisting of: --CO--R n --CO, --NH--R'--NH, and --CO--R"--NH units wherein 5-35 mol% of the total quantity of radicals R, R' and R" are flexible radicals selected from the group consisting of tetramethylene radicals, butenylene radicals, and tetramethylene or butenylene radicals substituted by one or more lower alkyl or halogen radicals; the remainder of the radicals, R, R' and R" consisting of rigid segments which can be identical or different and the majority of which are selected from the group consisting of p-phenylene, trans-1,4-cyclohexylene, trans-trans-1,4-butadienylene, and 2,5-pyridylene segments or their derivatives substituted by one or more lower alkyl or halogen radicals; and wherein n is 0 or 1 provided that when R' is flexible it can only be present as tetramethylene or substituted tetramethylene, in an amount of 5-20 mol% of the total quantity of radicals R, R' and R" and in the sequence: --NH--R"--CO--NH--R'--NH--CO--R"--NH-- and that no unit --CO--R"--NH-- is linked directly to another --CO--R"--NH--, said copolyamide consisting essentially of at least 10% by weight of the composition.