A polyimide film contains fluorinated substituents and cardo structures. The polyimide film exhibits excellent heat-resistance, transparency and mechanical properties. The polyimide film has a glass-transition temperature (Tg) of at least 360 C., a coefficient of thermal expansion (CTE) of 50 ppm/ C. or lower, a modulus of at least 4.0 Gpa, a b* value of 5 or lower and yellowness index of 8 or less. The polyimide film can be used as a display substrate or an optical film in a liquid crystal display (LCD), an organic light-emitting diode (OLED) and in other fields where the characteristic features are required.

Disclosed herein is a high thermal resistant polyolefin-based separator including a coating layer containing polyamic acid.

Specifically, the separator includes a polyolefin-based substrate film, and a coating layer containing polyamic acid formed on one or both surfaces of the polyolefin-based substrate film, wherein the polyamic acid contains one or more functional groups selected from the group consisting of a sulfone group, a trifluoromethyl group, an alkyl group, and a phenyl ether group.

Also, disclosed herein is an electrochemical battery having improved thermal stability by using the separator including a coating layer containing polyamic acid.

The present invention relates to a liquid crystal alignment composition comprising first liquid crystal alignment polymer; second liquid crystal alignment polymer; and a cross-linking agent compound, a method for preparing a liquid crystal alignment film using the same, a liquid crystal alignment film and a liquid crystal display using the same.

The present invention relates to a liquid crystal alignment agent composition comprising a polymerizable liquid crystal alignment polymer; and a catalyst precursor compound of a specific structure, a method for preparing a liquid crystal alignment film using the same, and a liquid crystal alignment film and a liquid crystal display using the same.

The present disclosure relates to a polyimide-based resin film which is synthesized by the reaction of an acid anhydride compound and a diamine compound having a specific structure, thereby capable of ensuring excellent flatness even under high temperature heat treatment conditions, and stably maintaining flatness even during further heat treatment, a substrate for display device, and an optical device using the same.

A polyimide polymer that includes the reaction product of: (a) at least one diamine selected from the group consisting of a diamine of Structure (Ia) and a diamine of Structure (Ib), ##STR00001##
(b) at least one diamine of Structure (II), ##STR00002##
(c) at least one tetracarboxylic acid dianhydride, and optionally (d) at least one compound containing a first functional group reactive with an amine or an anhydride and at least one second functional group selected from the group consisting of a substituted or unsubstituted alkenyl group and a substituted or unsubstituted alkynyl group. Each variable in the above formulas is defined in the specification.

The present disclosure relates to a polyimide-based resin film which is synthesized by the reaction of an acid anhydride compound and a diamine compound having a specific structure, a substrate for display device, and an optical device using the same.

The present invention provides a liquid crystal display device with a high degree of freedom in molecular structure design of an alignment film and with reduced image sticking. The liquid crystal display device includes a pair of substrates; a liquid crystal layer held between the substrates; an alignment film disposed on a liquid crystal layer side surface of at least one of the substrates; and a polymer layer disposed between the liquid crystal layer and the alignment film, the alignment film containing a first polymer containing at least one structure represented by the following formula (1) in a side chain, ##STR00001##
wherein R.sup.1 represents a C3-C6 branched or cyclic alkylene group, and a hydrogen atom at a para position to a carbonyl group in the phenyl group is optionally replaced.

The present invention aims to provide an alignment film capable of sufficiently reducing image sticking and stain in a liquid crystal display device, and a liquid crystal display device including a photo-alignment film and sufficiently reducing image sticking and stain. The alignment film of the present invention contains a polymer containing a nitrogen radical-containing group, and a photo-functional group. The nitrogen radical-containing group is preferably a hydrazyl radical-containing group represented by the following formula (I) or (II): ##STR00001##
wherein R.sup.1 is a direct bond or a divalent organic group; Me is a methyl group; and Bu is a butyl group.

The invention discloses a preparation method of a polyimide film having a low dielectric constant and high fracture toughness; in the method an aromatic diamine solution is firstly prepared, and then a poly(5-norbornene-2,3-dicarboxylic anhydride-alt-maleimide isobutyl polyhedral oligomeric silsesquioxane) and aromatic dianhydride are ground, uniformly mixed, added to the aromatic diamine solution, and stirred to obtain a poly(5-norbornene-2,3-dicarboxylic anhydride-alt-maleimide isobutyl polyhedral oligomeric silsesquioxane)/polyamic acid solution; the solution is uniformly applied on a clean glass sheet, then placed in a vacuum drying oven, cooled to room temperature, and then a film is peeled off in water by ultrasonic and dried under vacuum to obtain the desired product. The dielectric constant of the film obtained by the invention is reduced to 2.2, and the elongation at break is increased by 272%, the tensile breaking energy is increased by 285%, showing greatly improved elongation at break and fracture energy, and good fracture toughness.