PURPOSE: To obtain a film which does not slide during high-speed winding and has good antiblocking property suitable for a nonmetallized product, by providing a polypropylene film with a specified part treated with corona discharge in the form of longitudinal stripes.
CONSTITUTION: A polypropylene film at least either of whose surfaces is provided with a part treated with corona discharge in the form of longitudinal stripes, composed of alternately arranged 2W30mm-wide parts strongly treated with corona discharge and 2W50mm-wide parts weakly treated with corona discharge, wherein the wet tension of the weakly treated part is 39dyn/cm or below, the difference in the wet tension between the strongly treated part and the weakly treated part is at least 1dyn/cm. When the width of the longitudinal stripe of the strongly treated part is below 2mm, the slide preventing effect is small, and when it is above 30mm, blocking is apt. to occur in the case of a narrow film of a width of below 50mm. Further, when the width of the longitudinal stripe is below 2mm, blocking is apt. of occur, and when it is above 50mm, an effect which is at most equivalent to that of a conventional art can be obtained in the case of a narrow film of a width below about 70mm.
YUUKI KAZUICHI
HOSODA MOTOMU
