Method for producing liquid crystalline polyester

The present invention relates to a method for producing a liquid crystalline polyester, especially an all-aromatic type liquid crystalline polyester, endowed with excellent mechanical characteristics and heat resistance, and more particularly, to a method for producing a liquid crystalline polyester comprising performing two-stage polymerization, i.e., melt polymerization for producing a prepolymer and solid-state polymerization, wherein solid-state polymerization is performed after completion of control of the number of aromatic ring terminal groups contained in the prepolymer to be present at a ratio not less than a predetermined value. The present invention provides a method for producing a liquid crystalline polyester which is produced from an aromatic carboxylic acid, an aromatic hydroxycarboxylic acid, an aromatic diol and/or an aromatic hydroxylamine, including a polymerization step (1) for producing a prepolymer of the liquid crystalline polyester and a solid-state polymerization step (2) for elevating the polymerization degree of the resultant prepolymer, the number of aromatic ring terminal groups of the prepolymer satisfying the following equation (i): [(the number of aromatic ring terminal groups)/[(the number of carboxylic terminal groups)+(the number of aromatic ring terminal groups)]]×100 7(%) (i). According to the invention, all-aromatic type liquid crystalline polyesters can be produced within a short time and at low cost.