The present disclosure relates to a method for manufacturing a polyimide film and a polyimide film manufactured thereby. In one embodiment, the method for preparing a polyimide film includes: preparing a polyamic acid by polymerizing a mixture containing an aromatic diamine and an aromatic acid dianhydride; preparing a first composition containing the polyamic acid, an amine-based catalyst, an acid anhydride-based dehydrating agent, and a solvent; and forming a polyimide film at 150° C. or less using the first composition, wherein the first composition contains the amine-based catalyst and the acid anhydride-based dehydrating agent in a molar ratio of 1:2 to 1:5.

The present invention relates to a transparent polyimide film containing a polyimide and a phosphate ester. The content of the phosphate ester based on 100 parts by mass of the polyimide is 3 parts by mass or more, preferably 5 to 100 parts by mass. It is preferable to use a phosphate ester that has a high birefringence reduction effect and with which a decrease in the tensile modulus of the film is small. In production of the polyimide film, it is preferable to employ a method in which: a solvent-soluble polyimide resin and a phosphate ester are dissolved in an organic solvent exhibiting solubility with respect to the polyimide resin to prepare a polyimide solution; the polyimide solution is applied onto a substrate; and the organic solvent is removed.

Provided are a composition for forming a polyimide film, a method for preparing the same, and a use thereof. According to an implementation, a polyimide film which has excellent heat resistance, is flexible, and has excellent bending properties, without deteriorating colorless and transparent optical properties may be provided. In addition, the polyimide film according to an implementation may be useful for various flexible display devices.

An embodiment relates to a composition for forming a polyimide film for a cover window capable of satisfying advanced performance required for a cover window, a process for preparing the same, and uses thereof. According to an embodiment, by providing a polyimide film for a cover window for use in optical applications because the polyimide film has no optical stains, implements excellent visibility, and implements excellent heat resistance and mechanical properties without deteriorating colorless and transparent optical properties. The polyimide film may be usefully used in various types of flexible display devices.

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.

In a first aspect, a single layer polymer film includes 60 to 99 wt % of a crosslinked polyimide, having a gel fraction in the range of from 20 to 100% and a refractive index of 1.74 or less, and 1 to 40 wt % of a colorant. A surface of the single layer polymer film has been textured and has a maximum roughness (S.sub.pv) of 6 μm or more, an L* color of 30 or less and a 60° gloss of 15 or less. In a second aspect, a coverlay for a printed circuit board includes the single layer polymer film of the first aspect. In third and fourth aspects, processes are disclosed for forming a single layer polymer film including a crosslinked polyimide film including a dianhydride and a diamine.

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 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.

Disclosed herein are a polyimide film for graphite sheets, a method of fabricating the same, and a graphite sheet fabricated using the same. The polyimide film is fabricated by imidizing a polyamic acid formed by reaction between a dianhydride monomer and a diamine monomer, wherein the reaction is carried out in the presence of a metal compound and the polyamic acid forms a chelate with metal ions.