| 摘要 |
PURPOSE:To prevent a product from changing in physical properties or being ununiformized in shape in a part corresponding to upper and lower end faces of a preform to increase a capacity in one molding cycle by coating at least either an upper mold molding surface or a lower mold molding surface with a porous body. CONSTITUTION:A mold for producing a PTFE (polytetrafluoroethylene) preform comprises a cylindrical side mold 7, an upper mold 1, and a lower mold 2. A PTFE paste composition 10 containing PTFE and a molding adjuvant is compression molded. A PTFE molded piece is produced by a paste extrusion method. In this case, at least one of molding surfaces 5, 6 of the upper and lower molds 1, 2 is coated with porous bodies 3, 4. In the production process, the PTFE paste composition 10 is compression molded in the state that the porous bodies 3, 4 are provided between the PTFE paste composition 10 and at least one of the molding surfaces 5, 6 of the upper and lower molds 1, 2. |
