To reduce a change rate of an elongation and eliminate a curl or a roll set even in a high temperature and high moisture environment by laminating centrifugal polypropylene films on both side surfaces of a base sheet via adhesive, and impregnating raw material layers with the adhesive to fix raw material fiber.
A release sheet is formed by laminating oriented polypropylene films 3 on both side surfaces of a base sheet 1 of a base material via adhesive 2 and further forming a release layer 4 on one surface of the film 3. The films 3 are laminated on both the surfaces of the sheet 1 to further improve the moistureproofness. The films 1 and the sheet 1 are not merely adhered, but the base sheet fiber is fixed so as to stop the movement of the fiber due to moisture by impregnating the layer of the sheet 1 with the adhesive 2.
SUGANO TSUGIO
KASHIWABUCHI YASUHIKO
