The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 06, 2002
Filed:
Feb. 20, 2001
Mitsui Chemicals, Inc., , JP;
Abstract
A process for preparing a polyhydroxycarboxylic acid having a weight average molecular weight of 50,000 to 1,000,000, which comprises a crystallizing step comprising (A) a step of heating pellets of a polyhydroxycarboxylic acid having a weight average molecular weight of 2,000 to 100,000 under stirring to a temperature from glass transition point or higher to a melting point or lower and heating until a defined result is attained, and (B) a step of heating the polyhydroxycarboxylic acid to a temperature of solid phase polycondensation reaction temperature, and a solid phase polycondensation reaction step of reacting the crystallized polyhydroxycarboxylic acid at an endothermic start temperature or lower of an endothermic peak as recognized upon temperature elevation analysis of the crystallized polyhydroxycarboxylic acid by using a differential scanning calorimeter.