Patent ID: 7022807

Claim:
A method for producing a liquid-crystalline polyester solution composition comprising an aprotic solvent and a liquid-crystalline polyester comprising: at least one of the repeating units selected from the group consisting of a repeating unit derived from aromatic diamine, a repeating unit derived from aromatic amine having a hydroxyl group, and a repeating unit derived from aromatic amino acid, wherein the at least one of the repeating units is from 10 to 35 mol % in the liquid-crystalline polyester, and at least one of the repeating units represented by formulae (1), (2) and (3): —O—Ar 1 —CO— (1) —CO—Ar 2 —CO— (2) —X—Ar 3 —Y (3) wherein Ar 1 represents 1,4-phenylene, 2,6-naphthalene or 4,4′-biphenylene, Ar 2 represents 1,4-phenylene 1,3-phenylene or 2,6-naphthalene, Ar 3 represents 1,4-phenylene of 1,3-phenylene, X represents —NH—, and Y represents —O— or —NH—, wherein the content of the repeating units represented by formulae (1), (2) and (3) is 30 to 80 mol %, 35 to 10 mol % and 35 to 10 mol %, respectively, in the liquid crystalline polyester and the method comprising the steps of: acylating at least one repeating unit selected from the group consisting of a hydroxycarboxylic acid providing the repeating unit represented by formula (1), an aromatic diamine, an aromatic amine having a hydroxyl group, an aromatic acid, and a repeating unit represented by formula (3) with an excess amount of a fatty acid anhydride to obtain an acylated compound, transesterification of the acylated compound and an aromatic dicarboxylic acid providing the repeating unit represented by formula (2) to obtain a liquid-crystalline polyester; dissolving the polyester in an aprotic solvent to obtain a liquid-crystalline polyester solution composition thereof.