A method of producing a polyimide polymer comprising reacting at least two dianyhydride monomers with at least two diamino monomers in a first solvent under conditions appropriate to form a polyamic acid and subsequently imidized through one or more methods to a polyimide polymer.

The present invention relates to a liquid crystal alignment composition for the preparation of a liquid crystal alignment film having enhanced alignment property and stability and exhibiting a high voltage holding ratio, a method for preparing a liquid crystal alignment film using the same, and a liquid crystal alignment film and a liquid crystal display device using the same.

Provided are a polyimide-based film, a window cover film, and a display panel including the same. More particularly, a polyimide-based film having excellent visibility, a window cover film using the same, and a display panel including the same are provided.

In a first aspect, a polyimide film includes a dianhydride and a diamine. The dianhydride, the diamine or both the dianhydride and the diamine include an alicyclic monomer, an aliphatic monomer or both an alicyclic monomer and an aliphatic monomer. The polyimide film has a b* of 1.25 or less and a yellowness index of 2.25 or less for a film thickness of 50 μm. The polyimide film is formed by: (a) polymerizing the dianhydride and the diamine in the presence of a first solvent to obtain a polyamic acid solution; (b) imidizing the polyamic acid solution to form a substantially imidized solution; (c) casting the substantially imidized solution to form a film; and (d) drying the film.

The present invention relates to a polyimide-based film exhibiting excellent visibility, a method for preparing same, and a display device including the prepared film. Particularly, the present invention relates to a polyimide-based film, a window cover film, and a display panel including same. The polyimide-based film maintains linear polarization with respect to incident polarization in the direction of an inclination as well as incident polarization in the direction of a normal line of the film.

A polyimide precursor solution is disclosed, and a colorless transparent polyimide film manufactured from the polyimide precursor solution. The polyimide precursor solution has diamines, a first dianhydride represented by biphenyl dianhydride, a second dianhydride represented by rigid alicyclic dianhydride, a third dianhydride represented by non-alicyclic dianhydrides and organic solvent. The colorless polyimide films have a modulus of 4.5 GPa or higher, a glass-transition temperature (T.sub.g) of 370° C. or higher, and a yellow index of 3.0 or lower. These polyimide films can be used as substrates for thin film transistor (TFT), touch sensor panel (TSP), and cover window applications in flexible display such as organic light-emitting diode (OLED), flexible liquid crystal display (LCD) and other fields.

A polyimide-based composition includes a polyimide precursor and a solvent, in which the polyimide precursor includes repeating units represented by Chemical Formula 1 to 3. A polyimide film is also made from the composition.

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The present invention provides a method for manufacturing a liquid crystal display device which requires a reduced light irradiation dose in the alignment treatment for a photo-alignment film and achieves a favorable contrast ratio and a viewing angle property. The method for manufacturing a liquid crystal display device includes, in the following order, the steps of: (1) forming on a substrate a film of a photo-alignment film material containing two or more polymers and a solvent; (2) pre-baking the film to evaporate the solvent; (3) post-baking the pre-baked film gradually at multiple temperatures from a low temperature to a high temperature; and (4) irradiating the post-baked film with polarized light, at least one of the two or more polymers being a photo-reactive polymer containing a photo-functional group in a side chain.

Disclosed is a manufacturing method of a liquid crystal display device which is a manufacturing method of a liquid crystal display device including a liquid crystal alignment film to which an alignment regulating force is imparted by a photo-alignment treatment, including: a film forming step of forming a film containing a polymer whose main chain is cleaved by irradiation with light; a photo-alignment step of imparting an alignment regulating force to the film formed in the film forming step by irradiation of the film with light in an atmosphere of a temperature lower than 100° C.; and a removing step of removing a low-molecular weight component generated by cleaving the main chain of the polymer through the light irradiation after the light irradiation. Also disclosed is a liquid crystal display device manufactured by the manufacturing method.

In a first aspect, a polyimide film includes a polyimide derived from a dianhydride and a diamine. The dianhydride, the diamine or both the dianhydride and the diamine include an alicyclic monomer, an aliphatic monomer or both an alicyclic monomer and an aliphatic monomer. The polyimide film has an L* of at least 90, a b* of 1.25 or less, a yellowness index of 2.25 or less and a haze of less than 1% for a film thickness of 50 μm. In a second aspect, an electronic device includes the polyimide film of the first aspect.