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Abstract

There is provided a polytetrafluoroethylene (PTFE) porous material which has improved adhesion and improved buckling resistance on bending without a tearing problem along a tubular axial direction. The porous material is composed of a polytetrafluoroethylene and a heat-meltable resin of which melting point is lower than that of the polytetrafluoroethylene, has fibril portions and node portions and characterized in that the fibril portions are mainly of the polytetrafluoroethylene, and the heat-meltable resin mainly constitutes the node portions and hardly constitutes the fibril portions. The porous material is produced by extruding powder for paste-extrusion, which comprises particles of the polytetrafluoroethylene produced by emulsion polymerization of tetrafluoroethylene and particles of the heat-meltable resin of which melting point is lower than that of the polytetrafluoroethylene, at a temperature which is not higher than the melting point of the heat-meltable resin optionally followed by rolling so that an unsintered material is obtained, stretching the unsintered material at a temperature which is not higher than the melting point of the heat-meltable resin, and then heat setting the stretched material at a temperature which is equal to or higher than the melting point of the polytetrafluoroethylene.

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First Claim