초록 ▼

A method for recuperating from saponification products of alkaline polyterephthalate with soda where both terephthalate ions are in acid form and the sodium ions are in the form of soda is disclosed. In this method the sodium terephthalate solution resulting from dissolving the saponification produc

A method for recuperating from saponification products of alkaline polyterephthalate with soda where both terephthalate ions are in acid form and the sodium ions are in the form of soda is disclosed. In this method the sodium terephthalate solution resulting from dissolving the saponification products are subjected to a step of electrochemical pre-acidification to bring the pH to 4 to 7. Thereafter an electrochemical acidification step by electrolysis is undertaken to precipitate the terephthalic acid in the anode section and recuperate the soda in the cathode section which can be recycled.

대표청구항 ▼

[ What is claimed is:] [1.]1. A process for producing a weak aromatic polycarboxylic acid which is insoluble in an aqueous acidic solution and which is polymerizable in the presence of a polyol, wherein said weak aromatic acid is one whose salts of alkaline metals are soluble in an alkaline solution

[ What is claimed is:] [1.]1. A process for producing a weak aromatic polycarboxylic acid which is insoluble in an aqueous acidic solution and which is polymerizable in the presence of a polyol, wherein said weak aromatic acid is one whose salts of alkaline metals are soluble in an alkaline solution above a pH of 7, which process comprises pre-acidifying an aqueous solution of an alkaline metal salt of said acid to bring the pH into a sub-precipitation pH range of said aromatic polycarboxylic acid, and electrochemically acidifying the pre-acidified solution in an anode compartment of an electrolysis cell, to induce precipitation of said aromatic polycarboxylic acid at the anode.