Resistoflex Corporation

Edward J Chu

Transfer molding of polypropylene, polyvinylidene fluoride, FEP fluorocarbon resin or PFA fluorocarbon resin to produce a lining for a 6' tee pipe fitting is accomplished isothermally by applying pressure of the order of 200 psi to the material while the material, the charge holding chamber and the tee mold are secured in a fixture in an oven. Transfer is performed at a stabilized resin temperature of the order of 375.degree. F. for polypropylene, 450.degree. F. for polyvinylidene fluoride, and 640.degree. F. for FEP and PFA resins over a relatively long time interval. Pressure is removed, the mold assembly is transferred to a press outside the oven, pressure of the order of 700 psi is reapplied to the material, and the mold is force cooled progressively from a remote point back toward the gate which is located in the fitting opposite the stack section thereof.

Isothermal transfer molding

A method is described whereby perfluoroalkoxy (PFA) fluorocarbon resin is fusion bonded to polytetrafluoroethylene (PTFE) resin to provide united sections thereof and to provide a bonded or welded interconnection between separate sections of PTFE resin. The welds are obtained under minimal positive pressure, generally below about 40 psi, at a temperature above the gel point of the PTFE resin, generally between 635.degree. F. and 710.degree. F., with subsequent slow cooling under pressures somewhat higher and generally ranging between about 59 psi and 150 psi.

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Parsippany, NJ, United States of America

Edward J Chu