Abstract: There is provided a method for plastic film surface treatment for improving printability and adhesion properties which comprises feeding a plastic film and a wiping web in the opposite direction to each other in a ratio of the film running speed to the wiping web running speed being 1/1 to 100/1 and bringing them into contact with each other between knip rolls under a proper pressure, whereby a weak layer containing oligomers and additives is wiped off from the plastic film surface. The treatment improves the printability and adhesion of film inexpensively in a stable manner without being affected by the varied properties of film to be treated and also without deteriorating the physical properties of the film.

Abstract: The present invention provides a polyimide film whose residual content of volatiles is reduced to not more than 0.45 weight % on the basis of the film, and further a polyimide film whose residual content of volatiles is reduced to not more than 0.45 weight % on the basis of the film and whose oxygen/carbon ratio in the surface layer is increased by 0.01-0.1, and manufacturing methods therefor.According to the present invention, it is possible to provide a polyimide film improved in adhesion performance in a stable and homogeneous manner, and this improvement of adhesion performance is attainable in the film-forming process, not in a separate process of after-treatment.

Abstract: A polyimide film produced by forming a film from a raw material incorporated with a finely divided inorganic powder that forms minute projections on the film surface and subsequently subjecting the film to corona discharge treatment. According to this invention, it is possible to obtain a heat-resistant polyimide film having improved adhesive properties and uniform bond strength. The film does not cause blocking when wound into a roll.

Abstract: A new polyimide film which contains 30 to 800 ppm of titanium based on the weight of the film, and a process for producing a new polyimide film which comprises introducing an organic titanium compound substance into the film-forming polyimide resin prior to the casting step. This process enables one to control the film surface forming process and improve directly the adhesive properties of the film.

Abstract: A polyamide acid composition for preparing a polyimide which is improved in the stability in a form of solution and can extend the pot life of the composition comprising a solution of a polyamide acid in an organic solvent, the polyamide acid being a precursor of the polyimide, and an N-substituted heterocyclic compound as a chemical treating agent which can lower a rate of conversion of the polyamide acid to the polyimide. The pot life can be extremely extended to give the composition an enough flowability for a long time without reducing the excellent properties such as a heat resistance of the obtained polyimide.

Abstract: A polyamide acid composition for preparing a polyimide which can extend the pot life of the composition comprising a solution of a polyamide acid in an organic solvent, the polyamide acid being a precursor of the polyimide, a dehydrating agent, a catalyst and a pot life extending agent which can lower a rate of conversion of the polyamide acid to the polyimide, and the process for preparing the polyimide from said polyamide acid composition. According to the present invention the pot life can be extremely extended to give the composition an enough flowability for a long time without reducing the excellent properties such as a heat resistance and an electric insulation of the obtained polyimide.