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

Abstract

This invention provides a liquid crystal alignment agent with high reworkability for resin films and liquid crystal alignment films, and provides a liquid crystal alignment agent capable of obtaining a liquid crystal alignment film with high light transmittance. One liquid crystal alignment agent contains a polymer (P) having a substructure (A) represented by formula (1). (In formula (1), Ya represents a divalent organic group having a substructure obtained by removing two hydrogen atoms from the structure represented by formula (NY) below. Z each independently represents a monovalent organic group having a chain hydrocarbon structure, and is bonded to a nitrogen atom through a carbon atom in the chain hydrocarbon structure. * represents an atomic bond to a carbonyl carbon.) (In formula (NY), E1 and E2 each independently represent a monovalent group having an aromatic ring and the aromatic ring being bonded to a nitrogen atom in formula (NY), or E1 and E2 combining to form a nitrogen-containing condensed heterocyclic structure (Cn) together with the nitrogen atoms bonded to E1 and E2. E3 is a hydrogen atom or a monovalent organic group. However, when E1 and E2 form a nitrogen-containing condensed heterocyclic structure (Cn), either of the following conditions (1) or (2) will be satisfied. (1) (1) A nitrogen-containing condensed heterocyclic structure (Cn) has two or more aromatic rings, and the two aromatic rings of the nitrogen-containing condensed heterocyclic structure (Cn) share a nitrogen atom in formula (NY) and are bonded together to form a condensed ring structure. (2) E3 has an aromatic ring, and the aromatic ring of E3 is bonded to a nitrogen atom in formula (NY).

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