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:
Nov. 17, 1981
Filed:
May. 27, 1980
Akitoshi Sugio, Ohmiya, JP;
Akira Amemiya, Tokyo, JP;
Tadashi Kunii, Yokkaichi, JP;
Tomotaka Furusawa, Matsudo, JP;
Mutsuhiko Takeda, Matsudo, JP;
Katsumasa Tanaka, Yokkaichi, JP;
Toshikazu Umemura, Tokyo, JP;
Mitsubishi Gas Chemical Company, Inc., Tokyo, JP;
Abstract
In a process for producing a stabilized oxymethylene copolymer which comprises heat-melting an oxymethylene copolymer having unstable, unblocked terminals obtained by the copolymerization of trioxane with a cyclic acetal and/or a cyclic ether to heat decompose it in the presence of available heat stabilizers; the improvement which comprises heating said oxymethylene copolymer having unblocked terminals in a mixer at a temperature between the melting point of said oxymethylene copolymer and a point 100.degree. C. higher than said melting point under a pressure of 0.1 mmHg to a atmospheric pressure for a mean residence time of 5 to 60 minutes, said mixer comprising a casing, a jacket for heating medium fitted over its external wall, and at least two stirring shafts equipped with a plurality of scraping blades disposed in said casing, said stirring shafts being capable of rotating in the same or different directions, and in the meantime, rotating said stirring shafts of said mixer to heat decompose said oxymethylene copolymer while renewing the surface of the molten oxymethylene copolymer.