Abstract: This invention provides a wafer processing film comprising a base film having a Shore D hardness of 40 or less and an adhesive layer disposed on one surface of the base film. In grinding the surfaces of wafers such as silicon and similar wafers, breakage can be prevented by affixing the wafers to the adhesive layer of the processing film and then grinding them.

Abstract: A gas permeable porous film which is prepared by stretching a film made from a mixture containing a polyolefin resin and an inorganic filler at least uniaxially and possesses a rugged pattern on its surface. One process for producing the film comprises forming the aforesaid mixture into a film, providing on the surface of the film a rugged pattern, stretching the resulting film at least uniaxially, and forming on the stretched film thus-formed a rugged pattern by means of a heated emboss roll and simultaneously allowing the stretched film to contract.

Abstract: A process for producing porous films which comprises blending 100 parts by weight of a polyolefin resin with 50 to 500 parts by weight of barium sulfate preferably having an average particle diameter of 0.1 to 7 .mu.m, melting the resulting resin composition and forming it into a film, and then stretching the film at least uniaxially by a factor of 1.5 to 7.

Abstract: A process for producing porous films which comprises melting a resin composition consisting essentially of (1) 100 parts by weight of a high-pressure-processed low-density polyethylene resin having a melt index of 0.5 to 7 and a density of 0.915 to 0.935, a linear low-density polyethylene resin having a melt index of 0.5 to 8.5 and a density of 0.915 to 0.935, or a mixture thereof and (2) 50 to 500 parts by weight of barium sulfate having an average particle diameter of 0.1 to 7 .mu.m; forming the molten resin composition into a film; and then stretching the film at least uniaxially by a factor of 1.5 to 7. As the linear low-density polyethylene resin, a copolymer of ethylene and hexene and/or octene is particularly preferred.

Abstract: A porous film having a good water vapor permeability is obtained with a high productivity by melting a resin composition comprising 100 parts by weight of a polyolefin resin and 50 to 500 parts by weight of barium sulfate having an electric conductivity of 250 .mu.S/cm or less in terms of the electric conductivity of a supernatant formed when the barium sulfate is added to water, and a particle size of 0.1 to 7 .mu.m, making the melt into a film and stretching the film to 2.5 to 14 times the original area at least in the uniaxial direction.