Aromatic copolyesters capable of forming an anisotropic melt

Claim 2

An aromatic polyester characterised in that it is capable of forming an anisotropic melt and contains 5 to 75 mole % of recurring units of formula: ##STR7## wherein R may be hydrogen, chlorine, bromine or alkyl groups containing from 1 to 4 carbon atoms.

Claim 3

An aromatic polyester according to claim 1 in which the units other than the oxycarboxyphenyl residues comprise equimolar proportions of residues of dihydric phenols and aromatic and/or cycloaliphatic dicarboxylic acids.

Claim 4

An aromatic polyester according to claim 2 wherein the acids are of formula: HOOC--X--COOH wherein X may be a radical selected from 1,4-phenylene, 1,3-phenylene, 1,2-phenylene, 5-sulpho-1,3-phenylene, 2-chloro-1,4-phenylene, 2-bromo-1,4-phenylene, 2-methyl-1,4-phenylene, 2,6-dimethyl-1,4-phenylene, 1,4-cyclohexylene, 4,4-biphenylene, 2,6-naphthalene, 4,4-biphenylene, ethylene dioxybis(1,4-phenylene) and radicals in which X may be: ##STR8## where W is --O--, --SO 2 -- or --C(CH 3 ) 2 -- and the dihydric phenols are of formula: --O--Y--O wherein Y is a divalent aryl radical comprising one or more fused or separate aromatic rings selected from 1,4-phenylene, 4,4'-biphenylene, 2,6-naphthalene, chloro, bromo, methyl, 2,6-dichloro, 2,6-dimethyl-1,4-phenylene or chloro-4,4'-biphenylene, 3,5',5,5'-tetra alkyl-4,4'-biphenylene and units of formula: ##STR9## where V is --O--, --C(CH 3 ) 2 --, or --SO 2 .

Claim 5

An aromatic polyester according to claim 2 in which the units other than the oxycarboxyphenyl residues include residues of hydroxyaryl carboxylic acids in which the hydroxyl and carboxyl groups are separated by at least three carbon atoms.

Claim 6

An aromatic polyester according to claim 1 in which the polyester consists solely of recurring units of formula: ##STR10## and residues of other hydroxyaryl carboxylic acids of formula: HO--A--COOH wherein A is a divalent aryl radical comprising one or more fused or separate aromatic rings and wherein the hydroxyl and carboxyl groups are separated by at least three carbon atoms.

Claim 7

An aromatic polyester according to claim 5 in which the hydroxyl and carboxyl groups of the acid of formula: HO--A--COOH are in para relationship in single or multi-ring systems and have their valences parallel and oppositely directed in condensed ring systems.

Claim 8

An aromatic polyester according to claim 5 consisting of recurring units of formulae: ##STR11## wherein the mole ratio of ortho-substituted residues to para-substituted residues is between 5:95 and 75:25.

Claim 9

An anisotropic melt of the aromatic polyesters according to claim 1.

Claim 10

A shaped article formed from an anisotropic melt according to claim 8.