Porous PTFE articles esp. bands prodn. - by sintering particulate PTFE and rotationally machining a band off

摘要

Porous PTFE articles are mfd. by charging particulate PTFE to a mould, in bulk density such that the charge is non-self-supporting; placing mould with charge into an oven held at between gel point of the PTFE and 475 degrees C; and sintering the polymer in the mould while still in the oven to cause the particle to adhere together. A porous PTFE web is mfd. by moulding a cylinder according to this process; rotating the resulting cylinder upon a lathe and producing the intended porous web by helically shaving a continuous sliver using a knife. Specifically, the oven temp. is 360-400 degrees C. The mould is kept in the oven so long that all PTFE particles reach or exceed gel temp. The mould is chosen so that one of its dimensions is 25mm. It is kept in the oven for 1-2 hr. When sintering is complete it is cooled to room temp.