Title:
PRODUCTION OF POLYBENZAZOLE AND METHOD FOR RECOVERING PHOSPHORIC ACID USED THEREFOR
Document Type and Number:
Japanese Patent JPH09296040
Kind Code:
A
Abstract:
To produce a polybenzazole at a low cost by recovering a waste phosphoric acid liquor formed in the step of producing the polybenzazole, purifying it, and reusing it.
In the production of a polybenzazole in a polyphosphoric acid as the polymn. solvent, a waste phosphoric acid liquor formed in the step of producing the polymer is purified with at least 0.01%, based on the waste liquor, of an active carbon and then concentrated under reduced pressure to a concn. of at least 70% to recover the phosphoric acid to be reused as the polymn. solvent. In the recovery of the waste liquor, the waste liquor is purified with at least 0.01%, based on the waste liquor, of an active carbon and then concentrated to at least 70% under reduced pressure.
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Inventors:
KUBOTA FUYUHIKO
Application Number:
JP10920196A
Publication Date:
November 18, 1997
Filing Date:
April 30, 1996
Export Citation:
Assignee:
TOYO BOSEKI
International Classes:
C08G75/32; C08G73/18; C08G73/22; C08G75/00; (IPC1-7): C08G73/18; C08G73/22; C08G75/32