PURPOSE: To obtain a netlike plastic perforated element reduced in pressure loss without generating the waste of a sheet due to punching while holding the voids of the sheet.
CONSTITUTION: Rows A each consisting of a large number of slits with a definite length (a) laterally arranged at a definite interval (d) and rows B each consisting of a large number of slits with a definite length (a) laterally arranged at a definite interval (d) so that the positions of the respective slits are shifted by (a+d)/2 with respect to the slits of the rows A are alternately and parallelly arranged to a porous sheet composed of a composite fiber consisting of a low m.p. resin and a high m.p. resin and having voids of 20-90vol.% at a definite interval. After the sheet is slitted, tension is applied to the sheet in the direction right-angled to the slits to stretch the sheet and, in this state, the sheet is thermally fixed within a temp. range from the m.p. of the low m.p. resin to the m.p. of the high m.p. resin to be molded into a netlike shape.
ITO AKIRA
KAWATO KAYOKO
IWAYA YOSHIAKI
