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. 01, 1994
Filed:
Aug. 03, 1992
Kureha Chemical Industry Co., Ltd., Tokyo, JP;
Abstract
Polyvinylidene fluoride (PVDF) having such crystallization properties as to produce small spheralite sizes without sacrificing properties, processability, purity, etc. comprises 99.5-96 wt. % of vinylidene fluoride and 0.5-4 wt. % of a comonomer selected from the group consisting of hexafluoropropylene, tetrafluoroethylene and mixtures thereof, has a logarithmic viscosity of 0.9-1.3 dl/g and a molecular weight distribution, as expressed by the ratio of weight average molecular weight to number average molecular weight, of 2.2-2.8. The PVDF is formed by suspension polymerizing vinylidene fluoride and 1-5 wt. % of the desired comonomer, in an aqueous medium in the presence of an oil-soluble initiator, so that a logarithmic viscosity [.eta..sub.1 ] of 1.3-1.9 dl/g is obtained at a vinylidene fluoride conversion of 10-50%; then adding a chain transfer agent to the medium and continuing polymerization so that the logarithmic viscosity [.eta..sub.2 ] of the final polymer is 0.3-0.7 dl/g lower than [.eta..sub.1 ] but remains in the range of 0.9-1.3 dl/g.