Abstract: An aromatic polyimide film having a TD linear expansion coefficient lower than that MD linear expansion coefficient is produced by an industrially advantageous process which is performed under such conditions that a self-supporting aromatic polyimide precursor film having a solvent content 25-45 wt % and an imidation ratio 5-40% is prepared and stretched in the transverse direction under heating initially at 80-240° C. and the stretched self-supporting aromatic polyimide precursor film is subsequently converted to a self-supporting aromatic polyimide film by heating the precursor film at 350-580° C.

Abstract: Provided are a method and apparatus for the production of a polyimide film, which allow a polyimide film having physical properties with in-plane uniformity to be produced with high productivity. In the method for the production of a polyimide film, a solvent content of a self-supporting film is measured by infrared spectroscopy, and based on the measurement result, one or more kinds selected from a drying condition of a cast of a polyimide precursor solution, a post-heating condition of the self-supporting film, and an amount of extrusion of a polyimide precursor solution from a die are controlled.

Abstract: The present invention provides a polyimide film having an anisotropic thermal expansion coefficient, and comprising a polyimide layer (b) and a polyimide layer (a) on one side or both sides of the polyimide layer (b), wherein the polyimide layer (a) is a layer of a polyimide prepared from a monomer component comprising a diamine having the structure of the following formula (1): wherein R represents a monovalent group selected from the groups listed as the following formula (2): wherein R1 represents a hydrogen atom or a methyl group, and two R1 groups may be the same as, or different from each other.

Abstract: The present invention provides a polyimide film for metallizing, which has an anisotropic thermal expansion coefficient, and comprises a polyimide layer (b) and a polyimide layer (a) on one side or both sides of the polyimide layer (b); wherein the polyimide layer (b) is a layer of a polyimide prepared from an acid component comprising 3,3?,4,4?-biphenyltetracarboxylic dianhydride and a diamine component comprising p-phenylenediamine; and the polyimide layer (a) is a layer of a polyimide prepared from a monomer component comprising at least one selected from the group consisting of phenylenediamines and diaminodiphenyl ethers as a diamine component, and contains a surface treatment agent.

Abstract: An adhesion-enhanced polyimide film which includes a core layer composed of a polyimide (a) having high rigidity and a low linear expansion coefficient, at least one side of which has a thin-layer formed by heating a coated layer including a heat-resistant surface treatment agent and a polyimide precursor which yields a highly heat-resistant amorphous polyimide (B).

Abstract: An aromatic polyimide film having a TD linear expansion coefficient lower than that MD linear expansion coefficient is produced by an industrially advantageous process which is performed under such conditions that a self-supporting aromatic polyimide precursor film having a solvent content of 25-45 wt. % and an imidation ratio of 5-40% is prepared and stretched in the transverse direction under heating initially at 80-240° C. and the stretched self-supporting aromatic polyimide precursor film is subsequently converted to a self-supporting aromatic polyimide film by heating the precursor film at 350-580° C.

Abstract: An aromatic polyimide film having a thickness in the range of 5-250 ?m and comprising biphenyltetracarboxylic acid units comprising 3,3?,4,4?-biphenyltetracarboxylic acid units and 2,3,3?,4?-biphenyltetracarboxylic acid units in a molar ratio of 75:25 to 97:3 and p-phenylenediamine units in a molar ratio of 100:102 to 100:98 has thermal resistance and physical characteristics equivalent to those of the known aromatic polyimide film comprising 3,3?,4,4?-biphenyltetracarboxylic acid units and p-phenylenediamine units and showing good thermal resistance and physical characteristics and is favorably produced in industry.

Abstract: A polyimide film having one smooth surface favorably employable for a substrate of a display or an electronic paper is prepared by the steps of forming a laminated film by coating a polyimide precursor solution containing no filler, in which the polyimide is prepared from an acidic component comprising 3,3?,4,4?-biphenyltetracarboxylic dianhydride and a diamine component comprising p-phenylene diamine, on one surface of a self-supporting film of a polyimide precursor solution containing a filler, in which the polyimide is prepared from an acidic component comprising 3,3?,4,4?-biphenyltetracarboxylic dianhydride and a diamine component comprising p-phenylene diamine; and heating the laminated film to perform imidization.

Abstract: Disclosed is a polyimide film for metallizing, which has a polyimide layer (a) containing a surface treatment agent on one side or both sides of a polyimide layer (b). A metal layer may be directly formed on the surface of the polyimide film by a metallizing method, thereby providing a metal-laminated polyimide film with excellent adhesiveness.

Abstract: An adhesion-enhanced polyimide film which includes a core layer composed of a polyimide (a) having high rigidity and a low linear expansion coefficient, at least one side of which has a thin-layer formed by heating a coated layer including a heat-resistant surface treatment agent and a polyimide precursor which yields a highly heat-resistant amorphous polyimide (B).

Abstract: An easily slidable polyimide film having a polyimide surface layer comprising a polyimide which is thermoplastic and has a glass transition temperature of 190–450° C., wherein there are dispersed in the polyimide of the polyimide surface layer, in a proportion of approximately 0.5–10 mass % based on the polyimide of the polyimide surface layer, wholly aromatic polyimide particles made of a polyimide comprising at least 80 mass % of a pyromellitic acid component and a p-phenylenediamine component, and having a median size of 0.3–0.8 ?m and a maximum size of no greater than 2 ?m, in at least about 1 ?m of the polyimide surface layer.

Abstract: An easily slidable polyimide film having a polyimide surface layer comprising a polyimide which is thermoplastic and has a glass transition temperature of 190-450° C., wherein there are dispersed in the polyimide of the polyimide surface layer, in a proportion of approximately 0.5-10 mass % based on the polyimide of the polyimide surface layer, wholly aromatic polyimide particles made of a polyimide comprising at least 80 mass % of a pyromellitic acid component and a p-phenylenediamine component, and having a median size of 0.3-0.8 ?m and a maximum size of no greater than 2 ?m, in at least about 1 ?m of the polyimide surface layer.

Abstract: A metal film/aromatic polyimide film laminate is composed of a composite aromatic polyimide film and a metal film, in which the composite aromatic polyimide film is composed of an aromatic polyimide substrate film having a linear expansion coefficient of 5×10−6 to 30×10−6 cm/cm/° C. in the temperature range of 50-200° C. (measured in machine direction), and a thin aromatic polyimide layer of polyimide prepared from a carboxylic acid component comprising a mixture of 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 2,3,3′,4′-biphenyltetracarboxylic dianhydride in a molar ratio of 50:50 to 90:10 and an aromatic diamine component composed of 1,3-bis(4-aminophenoxy)benzene or a mixture of 1,3-bis(4-aminophenoxy)benzene and p-phenylenediamine and/or diaminodiphenyl ether in a molar ratio of 10/90 or more. Tg of the thin polyimide layer is 210-310° C. The metal film is fixed to the thin polyimide layer at a 90° peel resistance of 0.

Abstract: A metal film/aromatic polyimide film laminate is composed of a composite aromatic polyimide film and a metal film, in which the composite aromatic polyimide film is composed of an aromatic polyimide substrate film having a linear expansion coefficient of 5×10−6 to 30×10−6 cm/cm/° C. in the temperature range of 50-200° C. (measured in machine direction), and a thin aromatic polyimide layer of polyimide prepared from a carboxylic acid component comprising a mixture of 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 2,3,3′,4′-biphenyltetracarboxylic dianhydride in a molar ratio of 50:50 to 90:10 and an aromatic diamine component composed of 1,3-bis(4-aminophenoxy)benzene or a mixture of 1,3-bis(4-aminophenoxy)benzene and p-phenylenediamine and/or diaminodiphenyl ether in a molar ratio of 10/90 or more. Tg of the thin polyimide layer is 210-310° C. The metal film is fixed to the thin polyimide layer at a 90° peel resistance of 0.

Abstract: An aromatic polyimide film composed of a biphenyltetracarboxylic acid unit and a phenylenediamine unit, and having a thickness of 5-150 &mgr;m and an elongation of 45-90% shows, in combination with an electroconductive film, improved mechanical characteristics, when it has the following tensile modulus and a tear resistance measured by Elmendorf tearing tester: a tensile modulus of 750-1,300 kg/mm2 and a tear resistance of 350-1,500 g/mm in the case that the thickness is 50 &mgr;m or less; a tensile modulus of 650-1,200 kg/mm2 and a tear resistance of 550-1,500 g/mm in the case that the thickness is 50-100 &mgr;m; and a tensile modulus of 550-1,100 kg/mm2 and a tear resistance of 550-1,500 g/mm in the case that the thickness is 100 &mgr;m or more.

Abstract: An aromatic polyimide film useful as a face for a magnetic recording material having a back face-side half stratum thereof containing principal filler fine particles which provide a low friction back face-side surface having a centerline average surface roughness of 2 to 10 m .mu.m, and a front face-side half stratum thereof free from the principal filler particles and optionally containing additional filler fine particles having a size of 0.05 to 0.7 time that of the principal filler particles in a concentration of 0.1 to 0.8 time that of the principal filler particles, which additional filler particles provide a high smoothness front face-side surface having a centerline average surface roughness (Ra) of 0.1 to 0.

Abstract: Disclosed is an aromatic polyimide film which is well resistant to sagging and dimensional change in the heat treatment. The aromatic polyimide film is formed from a polymer solution which is produced by a polymerization reaction of a biphenyltetracarboxylic acid component and a phenylenediamine component, and characterized in that any rectangle optionally supposed within the film has a ratio between a length of any side and a length of the central portion between the side and a side opposite thereto is in the range of 100:100 to 100:100.15, and a heat shrinkage ratio of the film is not more than 0.3% (0.003) in any direction after the film is heated at 300.degree. C. for 2 hours. A process for the preparation of the above aromatic polyimide film is also disclosed.