| 摘要 |
PROBLEM TO BE SOLVED: To provide a filtering material which is a polytetrafluoroethylene (PTFE) porous film having pores and capable of efficient filtration and which can be easily pleating processed, and to provide a production method thereof.SOLUTION: A composite body includes a PTFE porous intermediate film having a PTFE porous film with pores of 2-20 nm as an intermediate layer and fluoropolymer porous films with pores of larger size as both of outer layers. A production method of the composite body includes: a step to separately apply high pressure to a PTFE sheet and a fluoropolymer-containing sheet; a step to form the PTFE porous film and the fluoropolymer porous film by making air holes in the respective sheets; a step to expose the respective porous films to high temperature, however, structures of the PTFE film and the fluoropolymer film are not stabilized; a step to arrange the PTFE porous film between two sheets of the fluoropolymer porous film; and a step to stabilize the structure of the film by exposing the three layered film to a temperature of 200°C or higher and lower than melting temperatures of PTFE and the fluoropolymer. |
