Importance

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Abstract

Dispersion polymerized PTFE itself, if provided in an unfused state, is sufficiently capable of acting as a pressure sensitive adhesive to facilitate the formation of an initial mechanical bond between components of a laminate such that it may be subsequently heat treated in a relatively short period of time to produce a well-bonded final laminate. This fact makes it possible to prepare a laminate comprising at least one layer containing PTFE by the steps of: (a) preparing a first dimensionally stable laminate component having two major surfaces, at least one of said major surfaces having an exposed layer comprising unfused PTFE; (b) preparing a second dimensionally stable laminiate component having two major surfaces, at least a first of said major surfaces being capable of forming an integral bond with the unfused PTFE-containing layer; (c) bringing said first and second laminate components together so that the exposed layer comprising unfused PTFE and the surface bondable with the unfused PTFE-containing layer are in contact with each other; (d) applying pressure to the combined laminate components at moderate temperature to achieve intimate contact and form a mechanical bond between the first and second laminate components; (e) introducing the mechanically bonded to a heating zone under conditions which avoid delamination; and (f) sintering the mechanically bonded laminate components in a heating zone to consolidate the unfused PTFE-containing layer. The mechanical bond formed is sufficiently strong that the consolidation can be done in a free-sintering process (no applied pressure). Application of pressure, however, is generally not detrimental to the product.

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First Claim