Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Woven fabric – Including a foamed layer or component
Patent
1998-07-23
2000-11-07
Copenheaver, Blaine
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Woven fabric
Including a foamed layer or component
156 77, 264 464, 427195, 4283135, 4283166, 442246, B32B 326, C08J 704, G03G 1520
Patent
active
061436755
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a porous composite material formed from polytetrafluoroethylene (PTFE) which has applications in a number of fields, particularly in the copying machine field, but also in the field of gas or liquid filtration, and in medicine. The invention also relates to oil transfer components containing the porous composite material for use in copying machines.
The term "copying machine" as used herein relates to machines which employ heated fuser rolls, for example printer devices such as plain-paper copying machines, fax machines, laser printers etc.
BACKGROUND OF THE INVENTION
In a plain-paper copying machine, toner images applied to the surface of paper or other recording medium are fixated by application of heat and pressure. In certain plain-paper copying machines fixation is accomplished by passing the image-bearing recording medium between a hot thermal fixation roll and a pressure roll. When this type of thermal fixation device is used the toner material is directly contacted by a roll surface and a portion of the toner usually becomes adhered to the roll surface. On material may be redeposited on the recording medium resulting in undesirable offset images, stains, or smears; or in severe cases the recording medium may stick to the adhered toner material on the roll and become wrapped around the roll. To counter these problems, materials having good release properties such as silicone rubber or polytetrafluoroethylene are often used for the roll surfaces. Although improving performance of the thermal fixation devices, use of silicone rubber or polytetrafluoroethylene roll surfaces alone does not eliminate the problem. Toner pick-up by the rolls can be controlled by coating the surface of at least one of the rolls with a liquid release agent, such as a silicone oil. It is important that the release liquid be applied uniformly and in precise quantities to the surface of the roll. Too little liquid or non-uniform surface coverage, will not prevent the toner from being picked up from the paper and deposited on the roll. On the other hand, excessive quantities of the release liquid may cause silicone rubber roll surfaces to swell and wrinkle, thus producing copies of unacceptable quality.
Various devices are known in the art for applying liquid release agent to one of the rolls of the fuser system, such as described in U.S. Pat. No. 3,831,553 and European Patent Publication 479564. However, the feature these systems have in common is the provision of a reservoir for holding a quantity of liquid release agent and an oil permeation control layer which is interposed between the reservoir and the roll of the fuser system for controlling the amount of oil which is transferred on to the roll of the fuser system. Various materials are known as the oil permeation control layer, such as porous polytetrafluoroethylene film as disclosed in Japanese Patent Specification No. 62-178992.
British published patent application 2242431 discloses a sintered porous polytetrafluoroethylene structure used as a filter in industrial filtration. The porous polytetrafluoroethylene material is produced by fusing particles of polytetrafluoroethylene such as to form a porous integral network of interconnected particles. The disclosure of this patent specification is incorporated herein.
British published patent application 2261400 (International Patent Publication W093/08512) discloses the use of such sintered porous polytetrafluoroethylene (PTFE) material as an oil transfer component in a copying machine and particularly as an oil permeation control layer to control the amount of release agent applied to the roll in the fuser system. Patent publication EP0174474 (Sumitomo) shows a release oil applicator which comprises a porous body formed of PTFE held in a housing. The PTFE body is saturated with silicone oil and may be formed with various cross-sections.
U.S. Pat. No. 4,336,766 (Maher) shows the use of a compound wick assembly formed from a relatively thick layer of Nomex felt and
REFERENCES:
patent: 3831553 (1974-08-01), Thettu
patent: 4336766 (1982-06-01), Maher et al.
patent: 4385093 (1983-05-01), Hubis
patent: 4443657 (1984-04-01), Hill et al.
patent: 4547424 (1985-10-01), Suzuki
patent: 5628786 (1997-05-01), Banas et al.
Clough Norman Ernest
McCollam Francis Michael John
Copenheaver Blaine
Lewis White Carol A
W. L. Gore & Associates (UK) Ltd.
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