The present invention relates to a polyimide film consisting essentially of a polyimide comprising a repeating unit represented by the following chemical formula (1):

##STR00001##

wherein the film has a YI (yellowness index) of 4 or less, a tensile modulus of elasticity of 4 GPa or more, and a load at break of 10 N or more.

The present invention provides a multilayer body of an inorganic substrate and a highly heat-resistant transparent film which has sufficient heat resistance and is able to be mechanically separated from the inorganic substrate after being subjected to various processes on the inorganic substrate since the adhesion between the highly heat-resistant transparent film and the inorganic substance is adequately weak. A multilayer body of a highly heat-resistant transparent film and an inorganic substrate, wherein: an adhesive is not substantially used; the peel strength between the highly heat-resistant transparent film and the inorganic substrate is 0.3 N/cm or less; and the CTE of the highly heat-resistant transparent film is 50 ppm/K or less.

A gas separation asymmetric membrane includes a porous layer having gas permeability; and a compact layer having gas separation capability which is formed on the porous layer in which the gas separation asymmetric membrane is formed using a polyimide compound which has a structural unit represented by Formula (I) and at least one structural unit selected from a structural unit represented by Formula (II) or a structural unit represented by Formula (III) and in which the viscosity, at 25° C., of a solution obtained by dissolving the polyimide compound in N-methylpyrrolidone at a concentration of 5% by mass is in a range of 2.2 to 22.0 mPa.Math.sec,

##STR00001##

in the formula, X.sup.1 represents a group having a structure represented by Formula (I-a) or (I-b).

##STR00002##

The present invention relates to a liquid crystal alignment agent composition including a copolymer for liquid crystal alignment agent containing two types of repeating units classified according to the types of diamine-derived functional groups, and a crosslinker compound in which the protecting group having a specific structure was introduced, 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.

A liquid crystal alignment agent and a preparation method thereof, a liquid crystal alignment film and a preparation method thereof, and a liquid crystal cell are provided. A piperazine monomer is added to a liquid crystal alignment agent, a bulk resistance value and a surface resistance value of a liquid crystal alignment agent material can be reduced, and the ability of the liquid crystal alignment agent material to release residual charges can be effectively improved, thereby increasing the reliability and stability of an electronic product. The liquid crystal cell using the liquid crystal alignment agent has advantages such as high voltage holding ratio (VHR) and low residual voltage.

The present application relates to a liquid crystal aligning agent, a liquid crystal alignment film and a method for producing the same, as well as a liquid crystal display device. The liquid crystal aligning agent comprises (i) a first polyamic acid having a photoreactive group without a liquid crystal group; (ii) a second polyamic acid having a liquid crystal group without a photoreactive group; (iii) a third polyamic acid having both a liquid crystal group and a photoreactive group; (iv) a fourth polyamic acid having neither a photoreactive group nor a liquid crystal group. The liquid crystal display device using the liquid crystal alignment film formed by the liquid crystal aligning agent provided by the present disclosure has a high display contrast and an improved AC residual image.

A method for producing a polyimide resin film, including: a coating step of forming a coated film by coating a polyimide resin composition containing a polyimide resin, an antioxidant, and a solvent on a substrate; and a drying step of drying the coated film in air at 180° C. or more, the antioxidant being a phenol-based antioxidant, and a content of the phenol-based antioxidant being 0.05 part by mass or more per 100 parts by mass of the polyimide resin.

A resin composition resulting in a cured article which is excellent in balance among mechanical strength, surface smoothness, and light transmittance, a method for producing a cured article, a cured article, and a flexible substrate or flexible display including the cured article. The resin composition includes a polyamic acid having a structural unit represented by the following formula (1), a cellulose compound having a weight average molecular weight of 60,000 or less, and an organic solvent. ##STR00001##
In the formula (1), A is a tetravalent organic group and B is a divalent organic group.

The present invention relates to a polyimide precursor comprising a repeating unit represented by the following chemical formula (1A) and a repeating unit represented by the following chemical formula (2A):

##STR00001##

wherein A.sub.1 is a divalent group having an aromatic ring; and R.sub.1 and R.sub.2 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms,

##STR00002##

wherein A.sub.2 is a divalent group having an aromatic ring; and R.sub.3 and R.sub.4 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms.

This invention relates to a method of evaluating monomers having an effect on copolymer characteristics and a system using the same, and particularly to a novel method of evaluating the magnitude of the effect of monomers on copolymer characteristics, which cannot be evaluated using existing methods. The method of evaluating monomers having an effect on copolymer characteristics and the system using the same are innovative because the extent of changes in copolymer characteristics can be predicted at the monomer level by quantitatively evaluating the effect of the monomers on the copolymer characteristics, taking into consideration the kind or linkage type of monomers.