| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject resin suitable for use as fine powder in a stretching operation after paste extrusion and having stretchability, fibrillation tendency and non-melting secondary processability by specifying a standard specific gravity, a rheometer pressure, a stress relaxation time, etc. SOLUTION: This polytetrafluoroethylene resin is obtained by bringing a standard specific gravity (ASTM-4895) to <=2.160, preferably <=2.157, a rheometer pressure (an extruding pressure, ASTM D-4895 Section 10.8) to >=25 MPa, preferably >=30 MPa, a stress relaxation time to >=650 sec., a strength at break to >=3.0 kgf (29.4 N), preferably >=3.1 kgf (30.38 N) and/or a creep (viscosity response) speed (365 deg.C) to <=0.1 min-1, preferably <=0.08 min-1. Here, the stretch means an increase of length and is expressed in relation to the original length. The stress relaxation time, the strength at break and the creeping speed are each measured by specific methods respectively.
|
