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.

A polyimide precursor film contains a polyimide precursor, in which a total content of a solvent containing water and a solvent other than water in the polyimide precursor film is 5 mass % or more and 40 mass % or less, and a mass ratio of water to the solvent other than water in the polyimide precursor film is 0 or more and 2.5 or less.

The present invention discloses a novel diamine that has a structure bearing an intramolecular imide group and additionally an amide-substituted aromatic ring group at opposite sides of the imide group. The use of the novel diamine as a polymerization ingredient in polyimide production can provide a polyimide film which has remarkably improved mechanical and thermal properties while maintaining optical properties.

The present invention provides an alignment film having excellent heat resistance and capable of suppressing generation of defects such as image sticking and stain, and a liquid crystal display device including the alignment film. The alignment film of the present invention contains a copolymer containing a repeating structural unit represented by the following formula (1), wherein X1 and X2 may be the same as or different from each other and are each represented by, for example, any of the following formulas (X-P1) to (X-P4); and Y is represented by, for example, any of the following formulas (Y-P1) to (Y-P4).

##STR00001##

Provided are a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element. The liquid crystal alignment agent at least comprises one of a polyamic acid solution and a polyimide solution. The polyamic acid solution is obtained by means of a polymerization reaction of diamine compound component A and dianhydride compound component B in a solvent, and the polyimide solution is obtained from the polyamic acid solution via a dehydration imidization treatment. The diamine component A at least comprises one of the diamine compounds represented by “formula 1”. The obtained liquid crystal alignment agent has a better liquid crystal alignment capability, an excellent effect on image sticking, and the effect that decomposition products resulting from light alignment are easy to remove. ##STR00001##

A method of producing a polyimide film, including obtaining a polyamic acid including a repeating unit of Chemical Formula 1:

##STR00001## wherein Ar.sub.1 and Ar.sub.2 are described in the specification; imidizing the polyamic acid to obtain a partially imidized polyimide; determining a sub-Tg temperature of the partially imidized polyimide; and heating the partially imidized polyimide in at least two steps to obtain a polyimide film, wherein a step transition temperature range is within the sub-Tg temperature ±30° C.

A resin film, in which at least one of polyimide layers is a non-thermoplastic polyimide layer having a linear thermal expansion coefficient of 1×10.sup.−6 to 30×10.sup.−6 (1/K), is shown. The non-thermoplastic polyimide layer is composed of a polyimide which is produced by reacting an anhydride component containing an aromatic tetracarboxylic anhydride with a diamine component, wherein the diamine component contains both a dimer acid-type diamine produced by replacing each of two terminal carboxyl groups in a dimer acid with a primary aminomethyl or amino group and an aromatic diamine, and the dimer acid-type diamine is contained in an amount of 1 to 15 mol % relative to the whole diamine component.

A transparent electro-conductive laminate comprising: a substrate film made of a polyimide; and a thin film made of an electro-conductive material and stacked on the substrate film, wherein the polyimide is a polyimide containing at least one repeating unit 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 one selected from the group consisting of a hydrogen atom, alkyl groups having 1 to 10 carbon atoms, and a fluorine atom, R.sup.4 represents an aryl group having 6 to 40 carbon atoms, and n represents an integer of 0 to 12], having a glass transition temperature of 350° C. to 450° C., and having a linear expansion coefficient of 30 ppm/° C. or less, the linear expansion coefficient being determined by measuring change in length under a nitrogen atmosphere and under a condition of a rate of temperature rise of 5° C./minute in a temperature range from 50° C. to 200° C.

Aspects of the present disclosure generally describe polyarylether ketones and methods of use. In some aspects, a composition includes one or more polymers of formulae (I), (II), or (III):

##STR00001##

Aspects of the present disclosure generally describe polyarylether ketones and methods of use. In some aspects, a composition includes one or more polymers of formula (IV):

##STR00001##