Patent attributes
A film that has high rigidity and high heat resistance and good releasability from a roughened copper foil surface, which is subjected to surface oxidization or etching treatment with acid, such as a black oxidized copper foil surface and that is suitable as a release film for producing an MLB; and a process for producing the same. A drawn film having a layer (A) which comprises a copolymer that is made from 4-methyl-1-pentene and ethylene or an α-olefin, except 4-methyl-1-pentene, having 3 to 20 carbon atoms and that comprises 80% or more by mole of 4-methyl-1-pentene, the thermal coefficient of contraction of the film being 20% or more in the film-drawn direction, or the peel area of the film being 50% or more when the film, together with a copper foil surface subjected to roughening treatment, is subjected to heating and pressing treatment. This film is suitable for producing an MLB and has good releasability from the roughened copper foil surface, for example, a black oxidized copper foil surface.
