A method for manufacturing a polyimide composite film for a flexible metal-clad substrate includes the following steps, providing a polyamide acid solution; providing fluorine polymer particles and mixing the fluorine polymer particles with a dispersant and an organic solution to prepare a fluorine polymer particle dispersion; forming a colloidal polyimide film from the polyamide acid solution; and coating the colloidal polyimide film with the fluorine polymer particle dispersion and then performing baking to form a polyimide composite film.

A poly(amide-imide) copolymer that is a reaction product of a diamine represented by Chemical Formula 1, a tetracarboxylic acid dianhydride including a compound represented by Chemical Formula 2, and a compound represented by Chemical Formula 3: ##STR00001## wherein, in Chemical Formulae 1 to 4, R.sup.1 to R.sup.4, A, and X are the same as defined in the specification.

A poly(amide-imide) copolymer that is a reaction product of a diamine represented by Chemical Formula 1, a tetracarboxylic acid dianhydride including a compound represented by Chemical Formula 2, and a compound represented by Chemical Formula 3: ##STR00001## wherein, in Chemical Formulae 1 to 4, R.sup.1 to R.sup.4, A, and X are the same as defined in the specification.

The invention relates to new polyimide solutions having ecological and toxicological benefits compared to existing polyimide solutions as well as well as b their use, in particular for coating applications.

The invention relates to new polyimide solutions having ecological and toxicological benefits compared to existing polyimide solutions as well as well as b their use, in particular for coating applications.

Provided is an electrophotographic belt having an endless shape including a base layer, wherein the base layer includes a polyimide film containing polyimide serving as a binder resin and a carbon nanotube, wherein the polyimide has an imidization ratio of 80% or more, wherein the carbon nanotube has at least one resin selected from the group consisting of: polyphenylsulfone; polysulfone; and polyethersulfone present on at least part of a surface thereof. The base layer has a tensile strength of 200 MPa or more in each of a peripheral direction thereof and a direction perpendicular to the peripheral direction.

Provided is an electrophotographic belt having an endless shape including a base layer, wherein the base layer includes a polyimide film containing polyimide serving as a binder resin and a carbon nanotube, wherein the polyimide has an imidization ratio of 80% or more, wherein the carbon nanotube has at least one resin selected from the group consisting of: polyphenylsulfone; polysulfone; and polyethersulfone present on at least part of a surface thereof. The base layer has a tensile strength of 200 MPa or more in each of a peripheral direction thereof and a direction perpendicular to the peripheral direction.

The embodiments relate to a polyamide-based composite film that has excellent curl characteristics, mechanical properties, and optical properties, as well as, in particular, is effective in preventing reflection in the visible light region, remarkably reduces the rainbow phenomenon, and achieves a texture similar to that of glass, and a display device comprising the same. There are provided a polyamide-based composite film, which comprises a base film comprising a polyamide-based polymer; and a functional layer disposed on the base film, wherein the in-plane retardation (Re) measured with light having a wavelength of 550 nm is 100 nm to 220 nm, and a display device comprising the same.

A transparent polyimide film, prepared from a copolymerized polyamide acid according to a chemical cyclization method, is provided. The copolymerized polyamide acid requires at least a semi-aromatic polyamide acid, and the semi-aromatic polyamide acid is formed by reacting cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) and 2,2′-bis(trifluoromethyl)diaminodiphenyl (TFMB). The molar number of dianhydrides of the semi-aromatic polyamide acid is more than 20% of the total molar number of anhydrides of the copolymerized polyamide acid, so that the transparent polyimide film has a light transmittance greater than 80%, a chroma b* less than 5, and a CTE less than 35 ppm/° C.

A crosslinked polyimide, a polyimide film and a method for preparing thereof, an organic light emitting diode (OLED) device. 4,40-diamino-400-N-carbazolyltriphenylamine and 1,2,4,5-cyclohexanetetracarboxylic dianhydride and a p-xylylenediamine crosslinker are introduced in the present invention. The introduction of a diamine monomer with a large volume of pendant groups increases an asymmetry of the polyimide, destroys a close structure of the polymer, and reduces crystallization properties of the polypolymer, thereby effectively increasing its transmissibility. At the same time, a cross-linked agent, p-xylylenediamine, is introduced, and the cross-linked agent widens a molecular chain spacing, so that the polyimide molecule has a larger free volume. At the same time, the formation of cross-linked is beneficial to reduce a polarizability of the molecule, thereby reducing a dielectric constant of the material. An OLED device with a novel low dielectric constant and high transmittance is prepared in this way.