Provided herein is a method for manufacturing a polyimide film, the method including the steps of: preparing a polyamic acid solution; preparing a polyamic acid composition by adding a dehydrating agent and an imidizing catalyst to the polyamic acid solution; and applying the polyamic acid to a support to form a film, followed by thermosetting the film in a heater, wherein the thermosetting step comprises a first heating step, a second heating step, and a third heating step, each of the first, the second, and the third step being carried out in a processing temperature range of 100° C. to 550° C.

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.

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.

Disclosed herein is a polyimide film that is obtained by imidizing a polyamic acid solution containing two or more dianhydride components selected from the group consisting of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), and pyromellitic dianhydride (PMDA), and a diamine component including m-tolidine and p-phenylenediamine (PPD) and has a glass transition temperature (Tg) of 320° C. or higher, a moisture absorption rate of 0.4% or less, and a dielectric dissipation factor (Df) of 0.004 or less.

The present application relates to a sizing agent composition, a carbon fiber material and a composite material. The sizing agent composition includes a first composition solution and a second composition solution, and those solutions respectively has specific compound. The sizing agent comprising the composition has an excellent bonding property with a carbon fiber, and further the sizing agent can efficiently enhance heat resistance, wear resistance and processability of the carbon fiber material. The carbon fiber material sized with the sizing agent has a high adhesion property with specific resin material, therefore producing the composite material with high processability.

A tetracarboxylic dianhydride represented by the following general formula (1): ##STR00001##
[in the formula (1), R.sup.1, R.sup.2, and R.sup.3 each independently represent a hydrogen atom and the like, and n represents an integer of 0 to 12], wherein a ratio of a summed amount of a specific stereoisomer (A) and a specific stereoisomer (B) is 50% by mole or more relative to a total amount of stereoisomers based on three-dimensional configurations of two norbornane rings in the general formula (1), and a content ratio of the stereoisomer (A) is 30% by mole or more relative to the total amount of the stereoisomers.

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.

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 particles of a metal compound having an average particle diameter (D.sub.50) of about 1 μm to about 6 μm.

Provided a diamine compound, a polyimide precursor and a polyimide film using the same, and a use thereof. The diamine compound may be very useful as a monomer for manufacturing a polyimide film having excellent transparency, high heat resistance, and low retardation.