KR-20260066157-A - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

KR20260066157AKR 20260066157 AKR20260066157 AKR 20260066157AKR-20260066157-A

Abstract

A liquid crystal alignment agent capable of obtaining a liquid crystal alignment layer that suppresses AC afterimages, the liquid crystal alignment layer, and a liquid crystal display element using the liquid crystal alignment layer are provided. A liquid crystal orientation agent comprising at least one polymer (P) selected from the group consisting of a tetracarboxylic acid component including at least one type selected from the group consisting of tetracarboxylic acid dianhydrides and derivatives thereof, a polyimide precursor obtained using a diamine component including a diamine represented by the following formula (2), and a polyimide which is an imid of the polyimide precursor. (The meaning of each symbol in the above formula is as defined in the specification.)

Inventors

이시카와 가즈노리
모리모토 요시미치
미야모토 야스히로
유키 다츠야

Assignees

닛산 가가쿠 가부시키가이샤

Dates

Publication Date: 20260512
Application Date: 20241107
Priority Date: 20231115

Claims (13)

A liquid crystal orientation agent comprising at least one polymer (P) selected from the group consisting of a tetracarboxylic acid component including at least one type selected from the group consisting of tetracarboxylic acid dianhydrides and derivatives thereof, a polyimide precursor obtained using a diamine component including a diamine represented by the following formula (2), and a polyimide which is an imid of the polyimide precursor. (In Formula (2), R21 to R24 independently represent a hydrogen atom, * -CO2R , or *-CONH-R, and at least two of R21 to R24 represent * -CO2R or *-CONH-R. Multiple Rs independently represent monovalent organic groups having 1 to 4 carbon atoms. One or more hydrogen atoms on the benzene ring bonded to the amino group may be substituted with a monovalent group other than * -CO2R or *-CONH-R. * indicates a bond.)
In Article 1, A liquid crystal orientation agent having a diamine content represented by formula (2) of 5 mol% or more per 1 mol of diamine component used in the manufacture of polymer (P).
In Article 1, A liquid crystal alignment agent in which the diamine represented by formula (2) is a diamine represented by any of the following formulas (2-1) to (2-4). (In the formula, t-Bu represents a tert-butyl group.)
In Article 1, The above tetracarboxylic acid dianhydride and its derivatives are selected from acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, or derivatives thereof, liquid crystal orientation agents.
In Article 4, A liquid crystal orientation agent having a content of acyclic aliphatic tetracarboxylic acid dianhydride, alicyclic tetracarboxylic acid dianhydride, aromatic tetracarboxylic acid dianhydride, or a derivative thereof, which is 10 mol% or more per 1 mol of tetracarboxylic acid component used in the manufacture of polymer (P).
In Article 1, A liquid crystal orientation agent comprising, wherein the above diamine component further comprises at least one other diamine selected from the group consisting of phenylenediamine, diaminobiphenyl compounds, diamines represented by the following formula (d AL ), diamines having a diphenyl ether structure, diamines having a tetracarboxylic acid diimide structure, diamines having an amide bond, diamines having a urea bond, and diamines having a group "-N(D)-" (D represents a protecting group that is detached by heating and substituted with a hydrogen atom). (Ar 1 and Ar 1' each represent a benzene ring, a biphenyl structure, or a naphthalene ring, and one or more hydrogen atoms on the benzene ring, the biphenyl structure, or the naphthalene ring may be unsubstituted or substituted with a monovalent group. L 1 and L 1' each represent a single bond, -O-, -C(=O)-, or -OC(=O)-. A represents -CH 2- , an alkylene group having 2 to 12 carbon atoms, or a divalent organic group formed by inserting at least one of -O-, -C(=O)-O-, and -OC(=O)- between the carbon-carbon bonds of the alkylene group.)
In Article 1, A liquid crystal orientation agent comprising, additionally, a polymer other than the polymer (P).
A liquid crystal alignment film obtained from a liquid crystal alignment agent described in any one of claims 1 to 7.
A liquid crystal display element having a liquid crystal alignment layer according to claim 8.
A method for manufacturing a liquid crystal display element comprising the following processes (1) to (4). Process (1): A process of applying a liquid crystal alignment agent described in any one of claims 1 to 7 to at least one of the first substrate and the second substrate. Process (2): A process of obtaining a film by firing the applied liquid crystal orientation agent. Process (3): A process of orientation treatment on the film obtained in Process (2). Process (4): A process of fabricating a liquid crystal cell by placing a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the oriented film.
In Article 10, A method for manufacturing a liquid crystal display element, wherein the above orientation treatment is a photo-alignment treatment.
In Article 11, A method for manufacturing a liquid crystal display element, comprising a process (3b) of additionally performing a heat treatment between process (3) and process (4).
In Article 12, A method for manufacturing a liquid crystal display element in which the liquid crystal display element is an IPS or FFS type liquid crystal display element.

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element. Liquid crystal display devices are widely used as display units for personal computers, smartphones, mobile phones, televisions, etc. A liquid crystal display device typically comprises a liquid crystal layer placed between a display element substrate and a color filter substrate, pixel electrodes and a common electrode that apply an electric field to the liquid crystal layer, an alignment layer that controls the orientation of liquid crystal molecules in the liquid crystal layer, and thin-film transistors (TFTs) that switch the electrical signal supplied to the pixel electrodes. Regarding the driving methods of liquid crystal molecules, front-field methods such as TN and VA methods, and transverse-field methods such as IPS (In Plane Switching) driving methods and FFS (FringeField Switching) driving methods are known. The most widely used liquid crystal alignment film in industry is produced by performing a so-called rubbing treatment, which involves rubbing the surface of a film formed on an electrode substrate, consisting of polyamic acid and/or polyimide formed by imidizing it, in a unidirectional manner with a cloth such as cotton, nylon, or polyester. Rubbing treatment is an industrially useful method that is simple and offers excellent productivity. As an alignment treatment method to replace rubbing treatment, photoalignment is known, which imparts liquid crystal alignment ability by irradiating with polarized radiation. Photoalignment methods utilizing photoisomerization reactions, photocrosslinking reactions, and photodecomposition reactions have been proposed (see, for example, Non-patent Literature 1 and Patent Literatures 1, 2, and 3). FIG. 1 is a schematic cross-sectional view showing an example of a liquid crystal display element of the transverse electric field type according to the present invention. FIG. 2 is a schematic cross-sectional view showing another example of a liquid crystal display element of the transverse electric field type according to the present invention. <Polymer (P)> The liquid crystal alignment agent of the present invention comprises a tetracarboxylic acid component comprising at least one type selected from the group consisting of tetracarboxylic acid dianhydrides and derivatives thereof, a polyimide precursor obtained using a diamine component comprising a diamine represented by formula (2) (also referred to as a specific diamine (p) in the present invention), and at least one polymer (P) selected from the group consisting of a polyimide which is an imid of the polyimide precursor. The polymer (P) may be one type or two or more types. Here, the polyimide precursor is a polymer that can obtain polyimide by imidizing polyamic acid, polyamic acid ester, etc. (Tetracarboxylic acid component) The polyamic acid (P'), which is a polyimide precursor of the polymer (P), can be obtained, for example, by the polymerization reaction of the specific diamine component and the tetracarboxylic acid dianhydride component. When preparing the polymer (P), the tetracarboxylic acid component reacted with the diamine component may be a tetracarboxylic acid dianhydride, as well as a derivative of the tetracarboxylic acid dianhydride such as tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, or tetracarboxylic acid dialkyl ester dihalide. Tetracarboxylic acid dianhydrides or derivatives thereof that can be used in the manufacture of polymer (P') may include, for example, acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, or derivatives thereof (hereinafter, these are also referred to as specific tetracarboxylic acid components). Among these, it is more preferable to include a tetracarboxylic acid dianhydride or a derivative thereof having at least one partial structure selected from the group consisting of a benzene ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring. In particular, it is even more preferable to include a tetracarboxylic acid dianhydride or a derivative thereof having at least one structure selected from the group consisting of a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring. In addition, aromatic tetracarboxylic acid dianhydrides are acid dianhydrides obtained by intramolecular dehydration of four carboxyl groups, including at least one carboxyl group bonded to an aromatic ring. A cyclic aliphatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups bonded to a chain hydrocarbon structure. However, it does not need to be composed solely of a chain hydrocarbon structure, and may have an alicyclic structure or an aroma