Patent ID: 6774203
Filing Date: 2004-08-10
Classification: C08G

Abstract:
In a method for producing a liquid crystalline polyester comprising at least an aromatic dicarboxylic acid (a), an aromatic diol (b), an aromatic hydroxycarboxylic acid (c), and/or an aromatic hydroxylamine (d) and exhibits anisotropy when stationary in a molten state, the method comprising:a polymerization step (1) for producing a prepolymer of the liquid crystalline polyester which is obtained by acylating a phenolic-hydroxyl-group of a phenolic-hydroxyl-group-containing aromatic compound by employing an aliphatic carboxylic acid anhydride (E) in an amount of 1.02-1.08 times to hydroxyl group equivalent of the phenolic-hydroxyl-group-containing aromatic compound, heating by elevating a temperature, performing a melt polymerization at a temperature higher or equal to a melting point of a prepolymer to be obtained, performing a maturing step to decarbonate a carboxyl group of a terminal aromatic hydroxycarboxylic acid (c) of a prepolymer so as to satisfy the following equation (i): [(the number of aromatic ring terminal groups)/[(the number of carboxylic terminal groups)+(the number of aromatic ring terminal groups)]]Ã—100&gE;7(%)â€ƒâ€ƒ(i), and a solid-state polymerization step (2) for elevating the polymerization degree of the resultant prepolymer.