BIAXIALLY ORIENTED POLYESTER FILM FOR MOLD RELEASE

摘要

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film for mold release that is especially suitable as a heat-resistant film for mold release with high process conformity which has a sufficient adhesion before a heating press, and has good detachability after the heating press in a circuit forming process which requires a mat tone by the reason that the biaxially oriented polyester film for mold release contains particles in high concentration, and a polarity force component in the surface free energy and a ratio of the real surface area of a film to a projected area are respectively in a suitable range.SOLUTION: There is provided a biaxially oriented polyester film for mold release which has a polyester layer A containing inorganic particles and/or organic particles in an amount of 1 mass% or more and 10 mass% or less based on 100 mass% of the total polyester layer A on at least an other outermost layer. A polarity force component in the surface free energy measured from the polyester layer A side of the outermost layer is more than 4.0 mN/m and 9.0 mN/m or less. The surface area S of the film per unit projected area are 1.01 or more and 1.15 or less.SELECTED DRAWING: None