Modified polytetrafluoroethylene fine powder and process for preparing the same

Abstract

Modified PTFE fine powder which comprises colloidal particles of a copolymer comprising repeating units derived from tetrafluoroethylene and 0.02 to 0.3% by weight, preferably 0.03 to 0.2% by weight of repeating units derived from at least one fluoroalkyl vinyl ether selected from compounds of the formula: X(CF.sub.2).sub.n OCF.dbd.CF.sub.2 (I) wherein X is a hydrogen, fluorine or chlorine atom and n is an integer of 1 to 6, and C.sub.3 F.sub.7 (OCF.sub.2 CF.sub.2 CF.sub.2).sub.m [OCF(CF.sub.3)CF.sub.2 ].sub.l OCF.dbd.CF.sub.2 (II) wherein m and l are each an integer of 0 to 4 provided that at least one of them is not zero, which has a number average particle size of 0.05 to 0.6 .mu.m, wherein the copolymer has a specific melt viscosity of from 6.times.10.sup.10 to 30.times.10.sup.10 poise, preferably from 8.0.times.10.sup.10 to 25.times.10.sup.10 poise at 380.degree. C. and a standard specific gravity (SSG, hereinafter defined) of from 2.135 to 2.175, preferably from 2.140 to 2.160 and a paste extruded article of the polymer has a green elongation of at least 400% is provided.

Dependencies are inferred from the claim text.