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US 5,670,189 AGranted
Compression molding two or more polytetrafluoroethylene resin layers to form a pressure pad
OwnerRobert E. Dalton, Myron A. Rudnerinventors
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OwnerRobert E. Dalton, Myron A. Rudnerinventors
Estimating the term…
Methods of compression molding powdered polytetrafluoroethylene resins to produce composite articles of manufacture having at least two distinct layers of two types of PTFE resin are disclosed. A first layer of resin, preferably including a filler, is placed in a compression mold and partially compressed at a relatively low pressure. A second layer of resin, preferably virgin resin, is then added to the mold and both layers are simultaneously fully compressed. After compression, the resulting composite preform is preferably sintered and coined to create a finished PTFE material or product. In a preferred embodiment, the partial compression step is performed at pressures of less than 500 psi. It has been found that modified PTFE resins provide improved resistance to cold flow and also provide better binding between filled and unfilled (virgin) layers and thus are used in certain preferred embodiments.
A pressure pad for use in a particleboard manufacturing apparatus comprising sheet of compression molded PTFE having a sliding surface comprised of a layer of virgin PTFE and a second layer comprised of layer of filled PTFE bonded together by partially compressing the first layer at a partial compression pressure less than 14.7 psi, and then compression and sintering both layers within a mold.
A pressure pad for use in a particleboard manufacturing apparatus comprising sheet of compression molded PTFE having a sliding surface comprised of a layer of virgin PTFE and a second layer comprised of layer of filled PTFE having significantly better resistance to cold flow than virgin PTFE wherein the layers are sintered together after being individually compressed and thereby resist delamination manufactured by the process of:
A pressure pad for compressing a sheet of material using a sliding surface, wherein the sliding surface comprises a first layer of virgin PTFE and a second layer of PTFE bonded together by partially compressing the first layer at a partial compression pressure less than 14.7 psi, and then compression and sintering both layers within a mold having significantly better resistance to cold flow than the virgin PTFE.
Dependencies are inferred from the claim text.