Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2007-02-13
2007-02-13
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C525S199000, C526S242000, C526S250000
Reexamination Certificate
active
10685789
ABSTRACT:
A process for producing low molecular weight, granular polytetrafluoroethylene or modified polytetrafluoroethylene by suspension polymerization of pressurized tetrafluoroethylene in an agitated reaction vessel. The polymerization is conducted in aqueous medium in the presence of a free radical initiator, and a telogen. The reaction vessel is agitated during polymerization sufficiently to coagulate the polytetrafluoroethylene or modified polytetrafluoroethylene. Low molecular weight granular polytetrafluoroethylene or modified polytetrafluoroethylene having a melt viscosity of less than about 1×106Pa·S powder is isolated directly from the reaction vessel. The low molecular weight polytetrafluoroethylene or modified polytetrafluoroethylene powder in accordance with the invention has a melt viscosity of less than about 1×106Pa·S, a specific surface area of less than about 8 m2/g, an extractable fluoride level of about 3 ppm or less by weight, and a narrow molecular weight distribution as indicated by a polydispersity index of about 5 or less. The particles of low molecular powder have a weight average particle size of about 2 to about 40 micrometers and the powder is substantially free of particles having a particle size of less than about 1 micrometer. The low molecular weight material so produced suitable for use as additives to other materials such as inks, coatings, greases, lubricants, and plastics.
REFERENCES:
patent: 3105824 (1963-10-01), Green et al.
patent: 3245972 (1966-04-01), Anderson et al.
patent: 3813449 (1974-05-01), Hartwimmer et al.
patent: 3855191 (1974-12-01), Doughty, Jr. et al.
patent: 3956000 (1976-05-01), Kuhls et al.
patent: 4262101 (1981-04-01), Hartwimmer et al.
patent: 4360618 (1982-11-01), Trementozzi
patent: 4487902 (1984-12-01), Fritschel
patent: 4580981 (1986-04-01), Bannai et al.
patent: 4587316 (1986-05-01), Nakagawa et al.
patent: 4703095 (1987-10-01), Nakagawa et al.
patent: 5118788 (1992-06-01), Hosokawa et al.
patent: 5405923 (1995-04-01), Aten
patent: 5461129 (1995-10-01), Kurihara et al.
patent: 5641571 (1997-06-01), Mayer et al.
patent: 5760151 (1998-06-01), Aten et al.
patent: 5973091 (1999-10-01), Schmiegel
patent: 6060167 (2000-05-01), Morgan et al.
patent: 1 262 496 (2002-12-01), None
patent: 51-41085 (1976-04-01), None
patent: 52-46993 (1977-11-01), None
patent: S57-22043 (1982-05-01), None
patent: WO 01/98384 (2001-12-01), None
patent: WO-2004/050727 (2004-06-01), None
E. I. du Pont de Nemours and Company
Hu Henry S.
Wu David W.
LandOfFree
Directly polymerized low molecular weight granular... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Directly polymerized low molecular weight granular..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Directly polymerized low molecular weight granular... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3843492