| 摘要 |
PROBLEM TO BE SOLVED: To provide a sealing medium which can obtain sufficient hardness, flexibility, and elasticity for use by a technique capable of obtaining a PTFE porous material having a fine texture, a smooth surface and good dimensional accuracy and easily controlling the porosity of the PTFE material. SOLUTION: The sealing medium uses a nonstretched PTFE porous material having a porosity of not less than 5% and only an endothermic peak in a fired state (perfect firing) in the crystal fusion curve by the differential scanning calorimetry (DSC) or the endothermic peak in a fired state (perfect firing) to the extent of not becoming clear. The sealing medium has a shape of pores oriented in a specific direction. The sealing medium uses a PTFE porous material obtained by mixing a PTFE powder with a pore-forming agent containing a dicarboxylic acid powder and an organic solvent to form a PTFE mixture, molding the PTFE mixture into a predetermined shape, and removing the pore-forming agent to provide pores. COPYRIGHT: (C)2009,JPO&INPIT
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