| 摘要 |
<p>A method of making a porous membrane comprises mixing a first fine powder PTFE resin and a second fine powder PTFE resin to form a PTFE resin mixture, the first PTFE resin having a characteristic of forming more and longer fibrils than the fibrils 24 formed from the second PTFE resin, and the second PTFE resin having a characteristic of forming thicker nodes 22 than nodes formed from the first PTFE resin. A perform is made of the mixture, which is extruded into a tape (42, fig 3). The tape is passed through a plurality of calender rolls (44, fig 3) to form a calendered tape (46, fig 3) having a thickness of about 380mum to about 1200Ánm. The calendered tape is stretched in a transverse direction to form a porous membrane (12, fig 3) comprising a plurality of nodes and fibrils, the membrane having a thickness of at least about 100Ám. The membrane formed may be a micro-filtration membrane.</p> |
