Abstract: The invention discloses a polyester film for leader tapes, including a polyester film having been brought into contact with an alkaline liquid and etched on at least one side to have a thickness pattern, wherein the polyester film has a tip portion having a thickness of 10 .mu.m or more and is 80% or less of the original thickness. The invention also includes a process for producing a polyester film for leader tapes including the steps of bringing a polyester film into contact with an alkaline liquid and etching the polyester film at least on one side to form a tip portion having a thickness of 10 .mu.m or more and 80% or less of the original thickness, with the etched depth controlled differently from position to position, for processing to have a desired thickness pattern.

Abstract: The present invention relates to a drawn plastic product with high strength, high modulus and excellent thermal dimensional stability and a method for preparation thereof.Practically, a drawn plastic product with high strength, high modulus and excellent thermal dimensional stability is obtained by drawing a plastic product, for example, a polyester or a polyamide product, in a low temperature plasma.

Abstract: This invention relates to a method and apparatus for imparting false twists to two yarns simultaneously. The significance of the invention resides in that an industrially utilizable method for false twisting yarns by frictional contact of two yarns with 4 rotating frictional discs has been provided. The apparatus of the present invention for practising the false twisting method is characterized in that the angle of contact of yarns with the frictional discs is maintained within a specific range and the frictional discs are attached to four shafts in specific order at specific heights. Various processes for preparing a variety of false twist yarns by utilizing the false twisting method and apparatus of the present invention have been established.