Abstract: An alkyldiamine having excellent polymerization reactivity, a polyimide comprising it as a constituting element, and a liquid crystal alignment film excellent in uniformity of liquid crystal alignment, are presented. Namely, the present invention relates to a diaminobenzene derivative represented by the following general formula (1) and to a polyimide obtained by reacting a diamine containing at least 1 mol % of the diaminobenzene derivative represented by the general formula (1), with at least one compound selected from a tetracarboxylic. dianhydride and its derivatives, to obtain a polyimide. precursor having a reduced viscosity of from 0.05 to 5.0 dl/g (in N-methylpyrrolidone at a temperature of 30° C., concentration: 0.5 g/dl) and ring-closing it, and having a repeating unit represented by the general formula (2). Further, the present invention relates to a liquid crystal alignment film containing at least 1 mol % of the above repeating unit.

Abstract: The present invention relates to a treating agent for liquid crystal alignment, which is an agent for liquid crystal alignment to be used for a method in which polarized ultraviolet rays or electron rays are irradiated on a polymer thin film formed on a substrate in a predetermined direction relative to the substrate plane, and said substrate is used for aligning liquid crystal without rubbing treatment, wherein said agent for liquid crystal alignment contains a polymer compound having photochemically reactive groups in the polymer main chain and a glass transition temperature of at least 200° C.

Abstract: A treating method for liquid crystal alignment, which comprises applying polarized ultraviolet or electron rays to a polymer thin film formed on a substrate, in a predetermined direction relative to the substrate surface, and using the substrate to align liquid crystal without rubbing treatment, wherein the polymer thin film is a polyimide resin containing a repeating unit of the formula (I): ##STR1## (wherein R.sup.1 is a tetravalent organic group having an alicyclic structure, and R.sup.2 is a bivalent organic group), which is obtained by dehydration ring-closure of a polyimide precursor having a reduced viscosity of from 0.05 to 3.0 dl/g (in N-methyl-2-pyrrolidone at temperature of 300.degree. C. at a concentration of 0.