A liquid crystal display including a first substrate, a thin film transistor disposed on the first substrate, a first electrode connected to the thin film transistor, and a first alignment layer disposed on the first electrode, wherein the first alignment layer includes polyimide and a capping group connected to a main chain end of the polyimide, and the capping group contains at least one of a first compound represented by the following Chemical Formula 1, and a second compound represented by the following Chemical Formula 2: ##STR00001## A1 and A2 are, independently of each other, an aromatic compound having 4 to 20 carbon atoms or an aliphatic cyclic compound having 4 to 20 carbon atoms; and B1 and B2 are, independently of each other, a crosslinking reaction group containing an alkylene group (—C.sub.nH.sub.2n—, n is a natural number).

Provided are a polyamic acid composition, a polyamideimide film thereof, and a method for preparing the polyamideimide film. More specifically, provided are a polyamideimide film capable of implementing excellent optical properties in addition to inherent physical properties of polyimide by using a polyamic acid composition including a combination of specific components, and a method for preparing the polyamideimide film.

A tetracarboxylic dianhydride includes: at least one acid dianhydride (A) selected from the group consisting of compounds each having an endo/exo type three-dimensional structure represented by a particular general formula and their enantiomeric compounds each having an exo/endo type three-dimensional structure; and/or an acid dianhydride (B) having an endo/endo type three-dimensional structure represented by a particular general formula, wherein a content of the acid dianhydride (B) in a total amount of the acid dianhydrides (A) and (B) is 30 to 100% by mole in a mole ratio.

A polyimide precursor comprising at least one repeating unit represented by the following chemical formula (5): ##STR00001##
in which A.sub.3 is a divalent group of an aromatic diamine or an aliphatic diamine, from which amino groups have been removed; and X.sub.3 and Y.sub.3 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and/or at least one repeating unit represented by the following chemical formula (6): ##STR00002##
in which A.sub.3 is a divalent group of an aromatic diamine or an aliphatic diamine, from which amino groups have been removed; and X.sub.4 and Y.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.

The present invention relates to a flexible and transparent polyimide laminate and manufacturing method thereof. The flexible and transparent polyimide laminate comprises a conductive layer, an adhesive layer and a polyimide substrate. The conductive layer includes a plurality of metal nanowires, and is attached on the polyimide substrate by the adhesive layer. The adhesive layer is an insoluble polyimide film and is polymerized by aromatic dianhydride and one of the following monomer: alicyclic diamines, fluorine-containing diamines, and the combination thereof.

Objects of the present invention are: to obtain a polyimide that is excellent in heat resistance, transparency, and optical isotropy and is soluble in an organic solvent; to provide, by using either a polyimide or a polyamic acid which is a precursor or the polyimide, a product or a member that is highly required to have heat resistance and transparency; and particularly to provide a product and a member both of which are obtained by applying a polyamic acid solution and a polyimide solution of the present invention to the surface of an inorganic substance such as glass, metal, metal oxide, or a single crystal silicon. These objects can be attained by a polyimide acid and a polyimide which are each prepared from an alicyclic tetracarboxylic dianhydride and a monomer having a fluorene structure.

To provide a liquid crystal display device having excellent liquid crystal vertical alignment properties, good transparency when a voltage is applied and good scattering properties when no voltage is applied, and good adhesion with the liquid crystal layer. The liquid crystal display device has a liquid crystal layer formed by irradiating and curing with ultraviolet rays a liquid crystal composition containing a liquid crystal and a polymerizable compound disposed between a pair of substrates provided with electrodes, and at least one of the substrates is provided with a liquid crystal alignment film to vertically align a liquid crystal. The liquid crystal composition contains a compound represented by the formula [1], and the liquid crystal alignment film is obtained from a liquid crystal alignment treating agent containing a polymer having a side chain structure represented by the following formula [2-1] or formula [2-2], and a side chain structure represented by the following formula [3]:

X.sup.1—X.sup.2—X.sup.3—X.sup.4—X.sup.5—X.sup.6x.sup.7.sub.pX.sup.8   [1]

(X.sup.1: the formula [1-a] to formula [1-g], etc., X.sup.2, X.sup.3, X.sup.4 and X.sup.6: a single bond, etc., X.sup.5 and X.sup.7: a benzene ring, etc., X.sup.8: a C.sub.1-18 alkyl group, etc.),

##STR00001##

(X.sup.A: H, etc., X.sup.B: a benzene ring, etc., X.sup.C: a C.sub.1-18 alkyl group, etc.),

—Y.sup.1—Y.sup.2—Y.sup.3—Y.sup.4Y.sup.5.sub.nY.sup.t   [2-1]

(Y.sup.1, Y.sup.2 and Y.sup.3: a single bond, etc., Y.sup.4 and Y.sup.5: a benzene ring, etc., Y.sup.6: a C.sub.1-18 alkyl group, etc.,

—Y.sup.7—Y.sup.8   [2-2]

(Y.sup.7: a single bond, Y.sup.8: a C.sub.8-22 alkyl group, etc.).

To provide a polymer material having properties that allow the polymer material to replace a polyimide and a polyamide synthesized from a petroleum raw material, said polymer material being synthesized from a raw material derived from natural molecules. [Solution] This polymer material is obtained by polymerizing a polymer raw material comprising a dimer of 4-amino cinnamic acid or a dimer of a 4-amino cinnamic acid derivative, which are natural molecules, wherein the carboxyl group is protected by an alkyl chain. The TGA curve of a polyamide acid (PAA-1) and a polyimide (PI-1) according to the present invention is shown in FIG. 5.

There is provided a polyimide precursor which can alter the hydrophilicity/hydrophobicity of the surface of a cured film formed readily even by a low level of ultraviolet ray irradiation; and a polyimide produced from the polyimide precursor. The polyimide precursor having a structure represented by the following formula (1): ##STR00001##
where A represents a tetravalent organic group; B represents a bivalent organic group having a thiol ester bond in its main chain; R.sup.1 and R.sup.2 independently represent a hydrogen atom or a univalent organic group; and n represents a natural number.

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.