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:
Feb. 02, 1999
Filed:
Aug. 15, 1996
Akira Nakai, Shizuoka, JP;
Kaoru Yamamoto, Shizuoka, JP;
Eiji Masuda, Shizuoka, JP;
Hiroyuki Kanai, Shizuoka, JP;
Polyplastics Co., Ltd., , JP;
Abstract
A process for producing a polyacetal copolymer, which is extremely heat-stable and is extremely reduced in the quantity of unstable terminals even in a high polymerization yield in which trioxane as the principal monomer, comprises copolymerization of trioxane as the principal monomer with a cyclic ether or cyclic formal having at least one carbon-to-carbon bond as the comonomer by using a specific heteropoly-acid or acid salt thereof as a polymerization catalyst until the content of the remaining monomers is lowered to at most 10% by weight based on all the monomers fed, adding 0.01 to 10% by weight, based on the resulting crude polymer, of a solution containing a catalyst deactivator, or contacting a basic gas as the deactivator to deactivate the catalyst, and subjecting the crude polymer as such to heat melting treatment without washing thereof.