Thermotropic aromatic polyesters having a high tenacity and an improved melt viscosity, and mouldings, filaments, fibres and films thereof

Claim 1

A thermotropic fully aromatic polyester prepared by reacting (a) p-hydroxybenzoic acid or p-hydroxybenzoic acid substituted by one or two of C 1 -C 4 alkyl, C 1 -C 4 alkoxy, C 6 -C 10 aryl, C 7 -C 12 alkylaryl or halogen; (b) isophthalic acid, terephthalic acid, or mixtures thereof which are unsubstituted or substituted by one or two C 1 -C 4 alkyl, C 1 -C 4 alkoxy, C 6 -C 10 aryl, C 7 -C 12 alkylaryl or halogen; (c) 2,7-dihydroxynaphthalene; and (d) up to 90 mole-percent based on the total amount of (c) and (d) of unsubstituted or substituted hydroquinone, resorcinol, bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-diphenylether, 4,4'-diphenylsulphide, 4,4'-diphenylsulphone or mixtures thereof and when substituted are substituted by up to four of halogen, phenyl or methyl; which polyesters contain the condensed radicals (a) in quantities of at least 40 mole-percent, based on the total of radicals (a), (b), (c) and (d), contain the condensed radicals (c) plus (d) in quantities of from 5 to 30 mole-percent, based on the total of radicals (a), (b), (c) and (d), with the limitation that the mol ratio of the condensed radicals b/(c+d) is from 0.95 to 1.05.