公开(公告)号：US3836574A

公开(公告)日：1974-09-17

申请号：US37166273

申请日：1973-06-20

Applicant: HOECHST AG

Inventor： ACHSEL E ,  SOMMER S

IPC: C08G63/78 ,  C08G17/01

CPC classification number: C08G63/78

Abstract: FILM-AND FIBER-FORMING POLYESTERS, OPTIONALLY ALSO POLYESTERS SUITABLE FOR THE PROCESSING OF PLASTIC ARTICLES, ARE PREPARED STARTING FROM DIOLS AND DICARBOXYLIC ACID/DICARBOXYLIC ACID ALKYL ESTER MIXTURE, IN WHICH THE PROPORTION OF THE NUMBER OF FREE CARBOXYL GROUPS SO THAT OF THE ESTERIFIED CARBOXYL GROUPS IS AT LEAST 60:40. THESE STARTING SUBSTANCES ARE REACTED TO FORM THE BIS-DIOL-DICARBOXYLIC ACID ESTERS AND THEIR LOWER OLIGOMERS, AND THESE SUBSTANCES ARE THEN POLYCONDENSED IN KNOWN MANNER TO FORM HIGH MOLECULAR WEIGHT POLYESTERS. PREFERABLY, POLYETHYLENETEREPHTHALATE IS PREPARED ACCORDING TO THIS PROCESS.

公开(公告)号：BR7105806D0

公开(公告)日：1973-06-28

申请号：BR580671

申请日：1971-09-02

Applicant: HOECHST AG

Inventor： ACHSEL E ,  SOMMER S

IPC: C08G63/78 ,  C07C69/88

公开(公告)号：BR7403648D0

公开(公告)日：1974-12-24

申请号：BR364874

申请日：1974-05-06

Applicant: HOECHST AG

Inventor： SEIPP H ,  HORTIG H ,  GILLER H ,  ACHSEL E

IPC: C07C69/82 ,  B01D9/02 ,  B01D11/00 ,  C07C67/06 ,  C07C69/08

Abstract: Crude DMT containing, as impurities mainly dimethyl isophthalate, dimethyl orthophthalate and p-toluic acid methyl ester, is purified with the use of solvents known to be useful for the recrystallization of DMT in such a manner that the crude DMT in molten state is introduced with agitation into the solvent, the temperature of which is maintained above the temperature of that eutectic mixture of DMT and the main impurities associated therewith which has the highest melting point. As soon as the solvent is saturated with DMT, pure DMT crystallizes. The process is preferably carried out continuously and in a special vertical counter-current washing column.