Transparent copolyamide from 1,10-disubstituted C11 diamine

Claim 1

A transparent copolyamide having a reduced specific viscosity of at least 0.5 dl/g, measured on a 0.5% solution of m-cresol at 25° C., which copolyamide is obtained by reaction of a mixture (A) consisting of essentially stoichiometric amounts of a diamine of the formula I ##STR16## and isophthalic acid or terephthalic acid, or amide-forming derivatives thereof, or a mixture of isophthalic acid and terephthalic acid, or amide-forming derivatives thereof, either with a mixture (B) consisting of essentially stoichiometric amounts of a diamine of the formula II ##STR17## and terephthalic acid or an amide-forming derivative thereof, or a mixture of terephthalic acid and isophthalic acid, or amide-forming derivatives thereof, in a molar ratio of terephthalic acid, or amide-forming derivative: isophthalic acid, or amide-forming derivative, of 8:2 to 10:0, or with a mixture (C) consisting of essentially stoichiometric amounts of a diamine of the formula III ##STR18## and terephthalic acid or isophthalic acid, or mixtures or amide-forming derivatives thereof, wherein R' and R" independently of one another are each hydrogen or methyl, R 1 to R 4 independently of one another are each hydrogen or alkyl having 1-4 C atoms, R 5 is alkyl having 1-12 C atoms, aryl having 6-10 C atoms, or said aryl substituted by alkyl having 1-4 C atoms, R 6 is hydrogen or alkyl having 1-6 C atoms, or R 5 and R 6 together are alkylene having 4-7 C atoms, R 7 is alkyl having 1-8 C atoms, R 8 is hydrogen or alkyl having 1-5 C atoms, R 9 is cycloalkyl which has 5-12 ring C atoms and which is unsubstituted or substituted by alkyl of 1-4 C atoms, R 10 is hydrogen or methyl, and R 11 is methyl, or R 10 and R 11 together are alkylene having 4-11 C atoms, the proportion of mixture (C) being 60-80 percent by weight, based on the total copolyamide, or the proportion of mixture (B) being 50-80 percent by weight, based on the total copolyamide, with the proviso that with a proportion of mixture (B) of up to 65 percent by weight, at most 70 mol.% of isophthalic acid, or of an amide-forming derivative thereof, in mixture (A) can be replaced by terephthalic acid or by an amide-forming derivative thereof, these weight percentages in the case of amide-forming derivatives of isophthalic acid or of terephthalic acid relating to identical functional groups.