PROCESS FOR THE RECOVERY OF NAPHTHALENEDICARBOXYLIC ACID FROM POLY(ALKYLENE NAPHTHALENEDICARBOXYLATE)

摘要

Disclosed is a process for the recovery of naphthalenedicarboxylic acid (NDA) from polyester materials prepared from and/or containing residues of NDA such as a poly(alkylene naphthalenedicarboxylate). In one embodiment, the process comprises contacting a polyester material prepared from and/or containing residues of NDA with water at a temperature of about 125 to 400 DEG C in a pressured vessel to obtain an aqueous slurry of NDA and recovering the NDA. A second embodiment of the process comprises contacting such a polyester with an aqueous, alkali metal base solution to obtain an aqueous solution of a di-akali metal naphthalenedicarboxylate salt, then neutralizing the aqueous solution with an acid to obtain an aqueous slurry or dispersoin of NDA and recovering the NDA. The process is particularly useful for recovering 2,6-naphthalenedicarboxylic acid (2,6-NDA) from poly(ethylene naphthalenedicarboxylate) polyesters.