Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Abstract

A liquid crystal aligning agent which contains a specific polymer (A) and a specific polymer (B) described below. Specific polymer (A): a polyamic acid which is obtained by reacting a tetracarboxylic acid dianhydride component that contains bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic acid dianhydride with a diamine component that contains at least one diamine compound as typified by 4,4'-diaminodiphenyl amine and 3,6-diaminocarbazole. Specific polymer (B): a polyimide precursor which has a structural unit represented by formula (7). (In formula (7), R represents a hydrogen atom or an alkyl group; Y represents a tetravalent organic group; and X represents a divalent organic group, with 10-100% by mole of X being a divalent organic group having one of the moieties represented by formulae (8)-(10) in the structure or a paraphenylene group.) (In formula (8), m1 represents an integer of 2-18.) (In formula (9), one or more arbitrary hydrogen atoms on the benzene rings may be substituted by monovalent organic groups other than primary amino groups; and m2 represents an integer of 1-8.) (In formula (10), one or more arbitrary hydrogen atoms on the benzene rings may be substituted by monovalent organic groups other than primary amino groups; and m3 represents an integer of 1-4.)

Description

technical field

[0001] This invention relates to the liquid crystal aligning agent used when forming a liquid crystal aligning film, a liquid crystal aligning film, and the liquid crystal display element using the same. Background technique

[0002] Currently, liquid crystal display elements are widely used as display devices. The liquid crystal aligning film which is a constituent member of a liquid crystal display element is a film which aligns a liquid crystal uniformly, and when liquid crystal orientation is insufficient, display failure called display unevenness and an afterimage tends to occur. Occurrence of display defects may be related to ionic impurities in liquid crystals, and as a method of reducing such impurities, a proposal such as Patent Document 1 has been proposed.

[0003] Moreover, in a liquid crystal aligning film, the orientation process called rubbing which wipes off the surface of a polymer film with a cloth is performed normally. However, if the ru...

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