| 摘要 |
PROBLEM TO BE SOLVED: To provide a PTFE sheet of which a PTFE porous sheet of no uneven performance can be manufactured. SOLUTION: When a mixture of PTFE fiber powder with a lubricant is passed through a mold and molded into a tubular shape and this tubular material is cut in the axial direction and formed into a sheet shape to manufacture a PTFE sheet, a mold shown in the figure is used. In the mold, the product (A×B) of the primary sectional area ratio (A) of (A)=(a<2> -a<2> )/(c<2> -b<2> ) defined in the formula 1 and the secondary sectional area ratio (B) of (B)=(c<2> -b<2> )/(d<2> -e<2> ) defined in the formula 2 is set in the range of 10-500, and the inner diameter enlargement ratio =e/b defined by the formula 3 is 1.0 or more, (in the formula, (a) represents the maximum inner diameter of a section forming a molding space on the primary side of a female mold, (b) represents the maximum outer diameter of a section forming a mold space on the primary side of a male mold, (c) represents the minimum inner diameter of a constricted section of a female mold, (d) represents the inner diameter of a section forming the minimum molding space width on the secondary side of a female mold, and (e) represents the outer diameter of a large diameter section forming the minimum molding space width on the secondary side of a male mold). This PTFE sheet is stretched at least in monoaxial direction to manufacture a PTFE porous sheet. |
