CN112400135B

CN112400135B - Liquid crystal aligning agent, liquid crystal alignment film, liquid crystal element, and method for manufacturing liquid crystal element

Info

Publication number: CN112400135B
Application number: CN201980046464.7A
Authority: CN
Inventors: 王道海
Original assignee: JSR Corp
Current assignee: JSR Corp
Priority date: 2018-08-24
Filing date: 2019-06-07
Publication date: 2024-03-29
Anticipated expiration: 2039-06-07
Also published as: WO2020039695A1; KR20210019096A; TW202009265A; CN112400135A; JPWO2020039695A1; JP7310823B2; KR102527238B1; TWI791838B

Abstract

The invention provides a liquid crystal aligning agent, a liquid crystal alignment film, a liquid crystal element and a method for manufacturing the liquid crystal element. The liquid crystal aligning agent comprises: a polymer component; cyclic siloxane compound [ A ] having a crosslinkable group]. Cyclic siloxane Compounds [ A ]]One form of (2) is a compound represented by the formula (1). In the formula (1), R ¹ ～R ⁶ Each independently represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Wherein R is ¹ ～R ⁶ At least one of them is a monovalent organic group having a crosslinkable group. n is an integer of 1 to 18. When n is 2 or more, a plurality of R ¹ The R's may be the same or different from each other ² May be the same or different from each other.

Description

Liquid crystal aligning agent, liquid crystal alignment film, liquid crystal element, and method for manufacturing liquid crystal element

Cross-reference to related applications

The present application is based on Japanese application No. 2018-157299, filed on 8/24/2018, the disclosure of which is incorporated herein by reference.

Technical Field

The present disclosure relates to a liquid crystal aligning agent, a liquid crystal alignment film, a liquid crystal element, and a method for manufacturing a liquid crystal element.

Background

The liquid crystal element includes a liquid crystal alignment film having a function of aligning liquid crystal molecules in a liquid crystal layer in a predetermined direction. In general, the liquid crystal alignment film is formed on a substrate by applying a liquid crystal alignment agent, which is obtained by dissolving a polymer component in an organic solvent, to the surface of the substrate, and preferably by heating.

In recent years, a large-screen and high-definition liquid crystal television has become a main body, and a small-sized display terminal such as a smart phone or a tablet PC (tablet personal computer) has become popular, and a demand for higher quality of a liquid crystal element has been increased as compared with the prior art. Therefore, various liquid crystal aligning agents have been proposed to improve the performance of a liquid crystal alignment film and to improve various characteristics of a liquid crystal element (for example, refer to patent documents 1 to 3).

Patent document 1 discloses that polyimide and an epoxy compound having a nitrogen atom (for example, N ' -tetraglycidyl-4, 4' -diaminodiphenylmethane, 1, 3-bis (N, N ' -diglycidyl aminomethyl) cyclohexane, and the like) are contained in a liquid crystal aligning agent. Patent document 2 discloses a liquid crystal aligning agent containing a polyamide acid or polyimide, and a compound containing an imide bond and 2 or more epoxy groups (for example, monoallyldiglycidyl isocyanuric acid, triglycidyl isocyanuric acid, and the like). Patent document 3 discloses a polyfunctional epoxy compound having 2 or more 3, 4-epoxycyclohexane rings and containing polyamide acid or polyimide in a liquid crystal aligning agent.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 10-333153

Patent document 2: japanese patent laid-open No. 2007-139949

Patent document 3: japanese patent laid-open publication 2016-170409

Disclosure of Invention

Problems to be solved by the invention

As described above, the liquid crystal element is used not only for a display terminal such as a personal computer but also for various applications such as a liquid crystal television, a car navigation system (car navigation system), a mobile phone, a smart phone, an information display (information display), a phase difference film, and a light control film, both indoors and outdoors. In addition, with the expansion of the use applications, it is assumed that the liquid crystal element is used in a more severe environment than before. Specifically, the liquid crystal element may be irradiated with a backlight for a long period of time due to continuous driving for a long period of time, used in a high-temperature environment, or exposed to a high-temperature environment. On the other hand, the demand for higher performance of liquid crystal elements has further increased, and it has been demanded that the element performance can be maintained even under severe environmental conditions.

The present disclosure has been made in view of the above-described circumstances, and a main object thereof is to provide a liquid crystal aligning agent which can obtain a liquid crystal element excellent in light resistance and heat resistance.

Technical means for solving the problems

According to the present disclosure, the following means are provided.

[1] A liquid crystal aligning agent comprising: a polymer component; a cyclic siloxane compound [ A ] having a crosslinkable group.

[2] A liquid crystal alignment film formed by using the liquid crystal alignment agent of [1 ].

[3] A liquid crystal element comprising the liquid crystal alignment film of [2 ].

[4] A method of manufacturing a liquid crystal element, comprising: a step of forming a photo-alignment film by applying the liquid crystal alignment agent of [1] to each of the substrate surfaces of a pair of substrates and irradiating the substrate surfaces with light; and a step of disposing a pair of substrates on which the liquid crystal alignment films are formed so as to face each other with the liquid crystal layer interposed therebetween, thereby constructing a liquid crystal cell.

[5] A method of manufacturing a liquid crystal element, comprising: a step of forming a coating film by applying the liquid crystal aligning agent of [1] to each of the conductive films of a pair of substrates having the conductive films; a step of disposing a pair of substrates on which the coating film is formed, with a liquid crystal layer interposed therebetween, so that the coating film faces each other, thereby constructing a liquid crystal cell; and a step of irradiating the liquid crystal cell with light in a state where a voltage is applied between the conductive films.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the liquid crystal aligning agent of the present disclosure, a liquid crystal element excellent in light resistance and heat resistance can be obtained by containing the polymer component and the cyclic siloxane compound [ a ].

Detailed Description

Liquid Crystal alignment agent

The liquid crystal aligning agent of the present disclosure contains a polymer component and an additive component. Further, a cyclic siloxane compound [ A ] having a crosslinkable group is contained as an additive component. Hereinafter, each component contained in the liquid crystal aligning agent and other components optionally blended as necessary will be described.

In the present specification, the term "hydrocarbon group" means a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The term "chain hydrocarbon group" refers to a linear hydrocarbon group and a branched hydrocarbon group each having a chain structure alone, and having no cyclic structure in the main chain. Wherein, the resin can be saturated or unsaturated. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group having a structure containing only alicyclic hydrocarbon as a ring structure, and not containing an aromatic ring structure. Among them, those having a chain structure in a part thereof are included without being composed of only alicyclic hydrocarbons. The term "aromatic hydrocarbon group" means a hydrocarbon group having an aromatic ring structure as a ring structure. The aromatic ring structure may be a chain structure or an alicyclic hydrocarbon structure.

< Polymer component >

The polymer component contained in the liquid crystal aligning agent is crosslinked by the cyclic siloxane compound [ A ]. The kind of the main skeleton of the polymer component is not particularly limited. Specific examples of the polymer component include polymers having polyamide acid, polyamide acid ester, polyimide, polyorganosiloxane, polyester, polyamide, polyamideimide, polystyrene, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, polymaleimide, styrene-maleimide copolymer, and poly (meth) acrylate as main backbones. Further, (meth) acrylate is meant to include acrylate and methacrylate.

Among these, at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and a polymer having a structural unit derived from a monomer having a polymerizable unsaturated bond is preferable in terms of facilitating a crosslinking reaction with the cyclic siloxane compound [ a ], improving compatibility with the cyclic siloxane compound [ a ], improving heat resistance when used in combination with the cyclic siloxane compound [ a ], and obtaining a liquid crystal element having higher reliability. The polymer component has a functional group (hereinafter, also referred to as "reactive functional group") capable of reacting with the crosslinkable group of the cyclic siloxane compound [ a ]. The reactive functional group may be appropriately designed according to the crosslinkable group of the cyclic siloxane compound [ A ]. Hereinafter, preferred examples of the polymer components will be described.

(Polyamic acid)

The polyamic acid can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound.

Tetracarboxylic dianhydride

Examples of the tetracarboxylic dianhydride used for the synthesis of the polyamic acid include: aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride, and the like. Specific examples of these include aliphatic tetracarboxylic dianhydrides: 1,2,3, 4-butanetetracarboxylic acid dianhydride, and the like;

examples of the alicyclic tetracarboxylic dianhydride include: 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, 1, 3-dimethyl-1, 2,3, 4-cyclobutanetetracarboxylic dianhydride, 2,3, 5-tricarboxyl cyclopentylacetic anhydride, 5- (2, 5-dihydroxytetrahydrofuran-3-yl) -3a,4,5,9 b-tetrahydronaphtho [1,2-c ] furan-1, 3-dione, 5- (2, 5-dihydroxytetrahydrofuran-3-yl) -8-methyl-3 a,4,5,9 b-tetrahydronaphtho [1,2-c ] furan-1, 3-dione, 2,4,6, 8-tetracarboxylic bicyclo [3.3.0] octane-2, 4,6, 8-dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, and the like; examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic anhydride, ethylene glycol bistrimethylene anhydride, and 4,4' -carbonyldiphthalic anhydride, and in addition to these, tetracarboxylic dianhydride described in japanese patent application laid-open No. 2010-97188 can be used. Further, the tetracarboxylic dianhydride may be used singly or in combination of two or more.

Diamine compound

Examples of the diamine compound used for the synthesis of the polyamic acid include: aliphatic diamines, alicyclic diamines, aromatic diamines, diaminoorganosiloxanes, and the like. Specific examples of these diamines include aliphatic diamines: m-xylylenediamine, 1, 3-propanediol, hexamethylenediamine, and the like; alicyclic diamines can be exemplified by: 1, 4-diaminocyclohexane, 4' -methylenebis (cyclohexylamine), and the like;

aromatic diamines may be exemplified by: hexadecyloxy-2, 4-diaminobenzene, octadecyloxy-2, 5-diaminobenzene, cholestanoxy-3, 5-diaminobenzene, cholestenoxy-3, 5-diaminobenzene, cholestanoxy-2, 4-diaminobenzene, cholestenoxy-2, 4-diaminobenzene, 3, 5-diaminobenzoate cholestanoyl ester, 3, 5-diaminobenzoate lanostanyl ester, 3, 6-bis (4-aminobenzoyloxy) cholestane, 3, 6-bis (4-aminophenoxy) cholestane, 2, 4-diamino-N, N-diallylaniline, 4- (4' -trifluoromethoxybenzoyloxy) cyclohexyl-3, 5-diaminobenzoate, 1-bis (4- ((aminophenyl) methyl) phenyl) -4-butylcyclohexane, 3, 5-diaminobenzoate=ζ -3-cholestan-1-yl group (E-1-below)

[ chemical 1]

(in the formula (E-1), X ^I X is X ^II Each independently is a single bond, -O-, -COO-, or-OCO- (wherein "+" means and X) ^I Binding bond of (2), R ^I Is alkanediyl having 1 to 3 carbon atoms, R ^II Is a single bond or an alkanediyl group having 1 to 3 carbon atoms, a is 0 or 1, b is an integer of 0 to 2, c is an integer of 1 to 20, and d is 0 or 1. Wherein a and b do not simultaneously become 0)

Side chain diamines such as the represented compounds:

p-phenylenediamine, 4 '-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoate, 4' -diaminoazobenzene, 3, 5-diaminobenzoic acid, 1, 5-bis (4-aminophenoxy) pentane, 1, 2-bis (4-aminophenoxy) ethane, bis [2- (4-aminophenyl) ethyl ] adipic acid, N-bis (4-aminophenyl) methylamine, 1, 4-bis- (4-aminophenyl) -piperazine, N, N '-bis (4-aminophenyl) -benzidine, 2' -dimethyl-4, 4 '-diaminobiphenyl, 2' -bis (trifluoromethyl) -4,4 '-diaminobiphenyl, 4' -diaminodiphenyl ether, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis (4-aminophenyl) hexafluoropropane 4,4'- (phenylenediisopropylenes) diphenylamine, 1, 4-bis (4-aminophenoxy) benzene, 4' -bis (4-aminophenoxy) biphenyl, 4'- [4,4' -propane-1, 3-diylbis (piperidine-1, 4-diyl) ] diphenylamine, 4 '-diaminobenzanilide, 4' -diaminostilbene, examples of the diaminoorganosiloxane include main chain diamines such as 4,4' -diaminodiphenylamine, 1, 3-bis (4-aminophenylethyl) urea, 1, 3-bis (4-aminobenzyl) urea, 1, 4-bis (4-aminophenyl) -piperazine, N- (4-aminophenylethyl) -N-methylamine, and N, N ' -bis (4-aminophenyl) -N, N ' -dimethylbenzidine, and diamines described in JP-A2010-97188 may be used in addition to these.

Synthesis of Polyamic acid

The polyamic acid can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound, optionally together with a molecular weight regulator (e.g., an acid monoanhydride, a monoamine, or the like). The ratio of the tetracarboxylic dianhydride and the diamine compound to be used in the synthesis reaction of the polyamic acid is preferably a ratio of 0.2 to 2 equivalents of the acid anhydride group of the tetracarboxylic dianhydride to 1 equivalent of the amino group of the diamine compound.

The synthesis reaction of the polyamic acid is preferably carried out in an organic solvent. The reaction temperature in this case is preferably-20 to 150℃and the reaction time is preferably 0.1 to 24 hours. Examples of the organic solvent used in the reaction include: aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and the like. Particularly preferred organic solvents are preferably selected from the group consisting of N-methyl-2-pyrrolidone, N-dimethylacetamide, N-dimethylformamide, dimethylsulfoxide, γ -butyrolactone, tetramethylurea, hexamethylphosphoric triamide, m-cresol, xylenol and halogenated phenols, or a mixture of one or more of these solvents with other organic solvents (for example, butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount (a) of the organic solvent to be used is preferably such that the total amount (b) of the tetracarboxylic dianhydride and the diamine is 0.1 to 50% by mass based on the total amount (a+b) of the reaction solution.

(Polyamic acid ester)

The polyamic acid ester can be obtained, for example, by the following method or the like: [I] a method of reacting a polyamic acid obtained by the synthesis reaction with an esterifying agent; [ II ] a method of reacting a tetracarboxylic acid diester with a diamine compound; [ III ] A method for reacting a tetracarboxylic acid diester dihalide with a diamine compound. The polyamic acid ester contained in the liquid crystal aligning agent may have only an amic acid ester structure, or may be a partially esterified product in which the amic acid structure and the amic acid ester structure coexist.

(polyimide)

Polyimide can be obtained, for example, by dehydrating and ring-closing a polyamic acid synthesized as described above and imidizing the same. The imidization ratio of the polyimide is preferably 20 to 99%, more preferably 30 to 90%, from the viewpoint of sufficiently conducting the crosslinking reaction with the cyclic siloxane compound [ A ]. The imidization rate represents the ratio of the number of imide ring structures to the total of the number of amic acid structures and the number of imide ring structures of the polyimide as a percentage. Furthermore, a part of the imide ring may be an isopolyimide ring.

The dehydrating ring closure of the polyamic acid is preferably performed by the following method: the polyamic acid is dissolved in an organic solvent, and a dehydrating agent and a dehydrating ring-closing catalyst are added to the solution and heated as necessary. In the above method, examples of the dehydrating agent include anhydrides such as acetic anhydride, propionic anhydride and trifluoroacetic anhydride. The amount of the dehydrating agent to be used is preferably 0.01 to 20 moles based on 1 mole of the amic acid structure of the polyamic acid. As the dehydration ring-closing catalyst, for example, tertiary amines such as pyridine, collidine, lutidine and triethylamine can be used. The amount of the dehydration ring-closing catalyst to be used is preferably 0.01 to 10 moles based on 1 mole of the dehydrating solvent to be used. Examples of the organic solvent used in the dehydration ring-closure reaction include organic solvents exemplified as users used in the synthesis of polyamic acid. The reaction temperature of the dehydration ring-closure reaction is preferably 0℃to 180 ℃. The reaction time is preferably 1.0 to 120 hours.

(Polymer having structural units derived from monomer having polymerizable unsaturated bond)

Examples of the polymer having a structural unit derived from a monomer having a polymerizable unsaturated bond (hereinafter, also referred to as "polymer [ Pm ]") include: and polymers (poly (meth) acrylate, styrene-maleimide copolymer, polystyrene, polymaleimide) obtained by using one or more of a (meth) acrylic acid compound, a maleimide compound, and a styrene compound as a monomer having a polymerizable unsaturated bond. The polymer [ Pm ] is preferably at least one selected from the group consisting of poly (meth) acrylate and styrene-maleimide-based copolymer, in terms of easy introduction of an alignment group and better reliability of the obtained liquid crystal element. In the case where the polymer [ Pm ] is a styrene-maleimide copolymer, the copolymer may further have a structural unit derived from a monomer (for example, a (meth) acrylic compound or the like) different from the styrene compound and the maleimide compound.

In the present specification, the "alignment group" is a group that can impart a pretilt angle to liquid crystal molecules in a liquid crystal layer when the liquid crystal alignment film is disposed adjacent to the liquid crystal layer. Specifically, there may be mentioned: a group capable of imparting a pretilt angle to liquid crystal molecules without irradiation with light (hereinafter, also referred to as a "homeotropic group"), and a photoalignment group. Specific examples of the vertical alignment base include: alkyl group having 4 to 20 carbon atoms, alkoxy group having 4 to 20 carbon atoms, fluoroalkyl group having 4 to 20 carbon atoms, fluoroalkoxy group having 4 to 20 carbon atoms, at least 2 rings (preferably at least one ring selected from the group consisting of cyclohexane ring, benzene ring and naphthalene ring) are bonded directly or via a divalent linking group (for example, oxygen atom, -CO-or-COO-) to form a group having a mesogen structure, a group having a steroid (steroid) skeleton, and the like.

The monomer used for synthesizing the polymer [ Pm ] is not particularly limited as long as it has a polymerizable unsaturated bond, and examples thereof include: a compound having a polymerizable unsaturated bond such as a (meth) acryloyl group, vinyl group, styryl group, vinylphenyl group, or maleimide group. Specific examples of these compounds include: unsaturated carboxylic acids such as (meth) acrylic acid, α -ethacrylic acid, maleic acid, fumaric acid, and vinylbenzoic acid; alkyl (meth) acrylates (e.g., unsaturated carboxylic acid esters such as methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cycloalkyl (meth) acrylate, benzyl (meth) acrylate, trimethoxysilyl propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, 3, 4-epoxycyclohexylmethyl (meth) acrylate, 3, 4-epoxybutyl (meth) acrylate, 4-hydroxybutyl glycidyl acrylate; unsaturated polycarboxylic acid anhydrides such as maleic anhydride: and (meth) acrylic compounds;

aromatic vinyl compounds such as styrene, methylstyrene, divinylbenzene, and 4- (glycidoxymethyl) styrene; conjugated diene compounds such as 1, 3-butadiene and 2-methyl-1, 3-butadiene;

Maleimide compounds such as N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4- (2, 5-di-oxo-3-pyrrolin-1-yl) benzoic acid, N- (4-glycidoxyphenyl) maleimide, N-glycidylmaleimide, 3-maleimidobenzoic acid, 3-maleimidopropionic acid, 3- (2, 5-di-oxo-3-pyrrolin-1-yl) benzoic acid, methyl 4- (2, 5-di-oxo-3-pyrrolin-1-yl) benzoate and the like.

In the case where the polymer [ Pm ] is a polymer having a photo-alignment group, a compound having a photo-alignment group can be used as the monomer having a polymerizable unsaturated bond. Specific examples of the compound having a photo-alignment group include a maleimide compound having a cinnamic acid structure, a (meth) acrylic compound having a cinnamic acid structure, and the like. The monomers having polymerizable unsaturated bonds may be used singly or in combination of two or more. In the present specification, "(meth) acryl" means "acryl" and "methacryl". "(meth) acrylic" means "acrylic" and "methacrylic".

The polymer [ Pm ] can be obtained, for example, by polymerizing a monomer having a polymerizable unsaturated bond in the presence of a polymerization initiator. The polymerization initiator used is preferably an azo compound such as 2,2' -azobis (isobutyronitrile), 2' -azobis (2, 4-dimethylvaleronitrile), or 2,2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile). The polymerization initiator is preferably used in a proportion of 0.01 to 30 parts by mass based on 100 parts by mass of the total monomers used in the reaction. The polymerization is preferably carried out in an organic solvent. Examples of the organic solvent used in the reaction include: alcohols, ethers, ketones, amides, esters, hydrocarbon compounds, and the like, preferably diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether acetate, and the like. The reaction temperature is preferably 30 to 120℃and the reaction time is preferably 1 to 36 hours. The amount (a) of the organic solvent to be used is preferably an amount of 0.1 to 60 mass% based on the total amount (a+b) of the reaction solution.

The weight average molecular weight (Mw) of the polymer component in terms of polystyrene as measured by gel permeation chromatography (Gel Permeation Chromatography, GPC) is preferably 1,500 ～ 500,000, more preferably 2,500 ～ 100,000. In the polymerization reaction for obtaining each polymer, when a reaction solution containing the polymer is obtained, the reaction solution may be directly used for the preparation of a liquid crystal aligning agent or may be used for the preparation of a liquid crystal aligning agent after the polymer is separated. The method for separating the polymer is not particularly limited, and may be carried out according to a known method.

In the case of imparting liquid crystal aligning ability to an organic film formed using a liquid crystal aligning agent by using a photo-alignment method, it is preferable that at least a part of the polymer component is a polymer having a photo-alignment group. The photo-alignment group refers to a functional group capable of imparting anisotropy to a film by a photoreaction such as a photoisomerization reaction, a photodimerization reaction, a photofries rearrangement (photo Fries rearrangement) reaction, or a photodecomposition reaction by light irradiation.

Specific examples of the light-directing group include: an azobenzene-containing group containing azobenzene or a derivative thereof as a basic skeleton, a cinnamic acid-containing group containing cinnamic acid or a derivative thereof (cinnamic acid structure) as a basic skeleton, a chalcone-containing group containing chalcone or a derivative thereof as a basic skeleton, a benzophenone-containing group containing benzophenone or a derivative thereof as a basic skeleton, a coumarin-containing group containing coumarin or a derivative thereof as a basic skeleton, a cyclobutane-containing structure containing cyclobutane or a derivative thereof as a basic skeleton, a stilbene-containing group containing stilbene or a derivative thereof as a basic skeleton, a phenylbenzoate-containing group containing phenylbenzoate or a derivative thereof as a basic skeleton, and the like. Among these, the photo-alignment group is preferably at least one selected from the group consisting of an azobenzene-containing group, a cinnamic acid structure-containing group, a chalcone-containing group, a stilbene-containing group, a cyclobutane-containing structure, and a phenyl benzoate-containing group, and is preferably a cinnamic acid structure-containing group or a cyclobutane-containing structure in terms of high sensitivity to light and easiness of introduction into the polymer.

The polymer having a photo-alignment group can be obtained, for example, by the following method: (1) A method obtained by polymerization using a monomer having a photo-alignment group; (2) A method of synthesizing a polymer having an epoxy group in a side chain and reacting the epoxy group-containing polymer with a carboxylic acid having a photo-alignment group. The content ratio of the photo-alignment groups in the polymer is appropriately set according to the type of photo-alignment groups so as to impart a desired liquid crystal aligning ability to the coating film. For example, in the case where the photo-alignment group contains a cinnamic acid structure, the content of the photo-alignment group is preferably 5 mol% or more, more preferably 10 to 60 mol% based on the total constituent units of the polymer having the photo-alignment group. When the photo-alignment group has a structure containing cyclobutane, the content of the photo-alignment group is preferably 50 mol% or more, more preferably 80 mol% or more, with respect to all constituent units of the polymer having the photo-alignment group. Further, the polymer having a photo-alignment group may be used singly or in combination of two or more.

The polymer component contained in the liquid crystal aligning agent may be a single polymer component, but is preferably a polymer blend (polymer blend) containing two or more polymers. In this case, two or more kinds of polymers are the same polymer (for example, polyamic acid and polyamic acid), and the types of monomers used may be different polymers from each other, or may be different types of polymers (for example, polyamic acid and polymethacrylate). When a crosslinking agent is blended in a polymer blend system, if the dispersibility of the crosslinking agent in the liquid crystal aligning agent is insufficient, the crosslinking reaction of the polymer using the crosslinking agent cannot be efficiently performed, and there is a concern that the effect due to the blending of the crosslinking agent cannot be sufficiently obtained. On the other hand, according to the cyclic siloxane compound [ A ], it is considered that the compatibility with the polymer and the solubility in a solvent are high, and the cyclic siloxane compound can be easily dispersed in the crosslinking points of the polymer. As a result, it is presumed that even when a polymer blend is produced, the reaction efficiency of the crosslinking reaction can be improved, and a liquid crystal element excellent in light resistance and heat resistance can be obtained.

As a preferred example of the liquid crystal aligning agent, the liquid crystal aligning agent contains a first polymer and a second polymer having a higher polarity than the first polymer. In this case, the second polymer having high polarity is biased to exist in the lower layer, and the first polymer is biased to exist in the upper layer, so that phase separation can be caused, and this is preferable. Preferred modes of the polymer component of the liquid crystal aligning agent include the following (I) to (III).

(I) The first polymer and the second polymer are in the form of a polymer selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide.

(II) one of the first polymer and the second polymer is one polymer selected from the group consisting of polyamic acid, polyamic acid ester and polyimide, and the other polymer is in the form of polymer [ Pm ].

(III) the first polymer and the second polymer are in the form of a polymer [ Pm ].

In the embodiment of (II), the total content of the polyamic acid, the polyamic acid ester, and the polyimide is preferably 20% by mass or more, more preferably 30% by mass or more, and still more preferably 50% by mass to 90% by mass, based on the total amount of the polymer components contained in the liquid crystal aligning agent, in order to sufficiently obtain the improvement effect by the polymer [ Pm ] and to achieve cost reduction. In the case where a liquid crystal aligning ability is imparted to an organic film formed using a liquid crystal aligning agent by a photo-alignment method, an alignment film having a high liquid crystal aligning property can be obtained by using the polymer [ Pm ] as a polymer having a photo-alignment group.

The content ratio of the polymer component in the liquid crystal aligning agent is preferably 50 mass% or more, more preferably 60 mass% or more, and even more preferably 70 mass% or more, based on the total mass of the solid components contained in the liquid crystal aligning agent (the total mass of the components of the liquid crystal aligning agent excluding the solvent), in terms of sufficiently improving the film strength.

< Cyclic siloxane Compound [ A ] >

The cyclic siloxane compound [ A ] is a cyclic compound having 1 cyclic skeleton formed by siloxane bonds (Si-O bonds) in the molecule, and has a crosslinkable group. The crosslinkable group is not particularly limited as long as it is a group capable of forming a crosslinked structure by covalent bonding with another group, and examples thereof include: ethylene oxide group, oxetanyl group, (meth) acryl group, allyl group, vinylphenyl group, cyclic carbonate group, hydroxymethyl group, amino group, and the like. The crosslinkable group is preferably at least one selected from the group consisting of an ethylene oxide group, an oxetane group and a (meth) acryl group, and particularly preferably an ethylene oxide group, in terms of improving the storage stability of the liquid crystal aligning agent. In the present specification, "(meth) acryl" means a compound containing "acryl" and "methacryl".

The number of crosslinkable groups in the molecule of the cyclic siloxane compound [ a ]1 is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more, in terms of sufficiently obtaining the effect of improving heat resistance and light resistance of the obtained liquid crystal element. In addition, the number of crosslinkable groups in the cyclic siloxane compound [ a ]1 molecule is preferably 10 or less, more preferably 8 or less, from the viewpoints of better compatibility with the polymer component, better dispersibility in the liquid crystal aligning agent, and suppression of performance degradation due to film shrinkage of the formed liquid crystal alignment film.

When a liquid crystal alignment film is formed using a liquid crystal alignment agent, a crosslinkable group of the cyclic siloxane compound [ a ] reacts with a reactive functional group of the polymer component by heating at the time of film formation, thereby forming a crosslinked structure. The combination of the crosslinkable group and the reactive functional group can be appropriately selected depending on the storage stability, ease of introduction into the polymer, reactivity to heat or light, and the like. Specifically, when the crosslinkable group is an epoxy group, the reactive functional group includes a carboxyl group, a hydroxyl group, an amino group, and the like, and is preferably a carboxyl group in view of good storage stability. In addition, when the crosslinkable group is a (meth) acryloyl group, the reactive functional group may be: thiol, (meth) acryl, and the like. When the crosslinkable group is a vinyl group, the reactive functional group includes a thiol group, a vinyl group, and when the crosslinkable group is an amino group, the reactive functional group includes: carboxyl groups, hydroxyl groups, epoxy groups, halogen atoms, and the like. When the crosslinkable group is a cyclic carbonate group, the reactive functional group may be an amino group, a hydroxyl group, a carboxyl group, an epoxy group, or an acid anhydride group, and when the crosslinkable group is a hydroxymethyl group, the reactive functional group may be: epoxy, amino, hydroxy, carboxyl, and the like. However, the present invention is not limited to the combination of these.

The cyclic siloxane compound [ A ] is preferably a compound represented by the following formula (1).

[ chemical 2]

(in the formula (1), R ¹ ～R ⁶ Each independently represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Wherein R is ¹ ～R ⁶ At least one of them is a monovalent organic group having a crosslinkable group. n is an integer of 1 to 18. When n is 2 or more, a plurality of R ¹ The R's may be the same or different from each other ² May be the same or different from each other)

In the formula (1), R is ¹ ～R ⁶ In the case of a monovalent organic group, specific examples thereof include: a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent group Q1 obtained by substituting at least one hydrogen atom of the monovalent hydrocarbon group with a crosslinkable group, and a process for producing the same having-O-between carbon-carbon bonds of hydrocarbon groups having 2 to 20 carbon atoms-COO-, -S-, -NR ¹⁰ -or-CONR ¹⁰ -(R ¹⁰ A monovalent group Q2 which is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms), a group Q3 in which at least one hydrogen atom of the monovalent group Q2 is substituted with a crosslinkable group, and the like, and these groups may have a substituent. Examples of the substituent include: hydroxyl groups, halogen atoms, and the like. At R ¹ ～R ⁶ In the case of a monovalent hydrocarbon group, the monovalent hydrocarbon group is preferably an alkyl group, an alkenyl group, or a phenyl group, more preferably an alkyl group.

The cyclic siloxane compound [ A ] in the liquid crystal aligning agent can be caused to ]In terms of better dispersibility and compatibility with polymer components and better solubility with respect to solvents, R ¹ ～R ⁶ Preferably a monovalent organic group having 1 to 20 carbon atoms, more preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent group Q1, a monovalent group Q2 or a monovalent group Q3.R is R ¹ ～R ⁶ The carbon number of (2) is preferably 1 to 15, more preferably 1 to 10.

At R ¹ ～R ⁶ In the case of the monovalent organic group having a crosslinkable group, the monovalent organic group having a crosslinkable group is preferably a group represented by the following formula (2).

* ¹ -R ⁷ -X ¹ …(2)

(in the formula (2), R ⁷ Is a divalent group having a chain structure, X ¹ Is a monovalent group having a crosslinkable group. ".1" means a bond to a silicon atom

In the formula (2), R ⁷ The chain structure of (C) is preferably an alkanediyl group having 1 to 10 carbon atoms or a divalent group having-O-or-S-between carbon-carbon bonds of an alkanediyl group having 2 to 20 carbon atoms, and may have a substituent. Examples of the substituent include a hydroxyl group and a halogen atom. The carbon number of R7 is preferably 1 to 7, more preferably 2 to 5.

X ¹ The monovalent group having an oxirane group, an oxetanyl group, a (meth) acryloyl group, an allyl group, a vinylphenyl group, a cyclic carbonate group, a hydroxymethyl group, or an amino group is preferable, and the monovalent group having an oxirane group, an oxetanyl group, or a (meth) acryloyl group is more preferable, and the monovalent group having an oxirane group (oxirane group or oxetanyl group) is particularly preferable from the viewpoint of storage stability of the liquid crystal aligning agent. Examples of the monovalent group having an epoxy group include: epoxy, glycidoxy, epoxycyclohexyl, and the like.

The 2 monovalent groups bonded to the silicon atom in the formula (1) are preferably at least one (R ¹ 、R ³ R is R ⁵ ) The other group (R) is a group represented by the formula (2) ² 、R ⁴ R is R ⁶ ) Is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R is R ² 、R ⁴ R is R ⁶ More preferably an alkyl group having 1 to 5 carbon atoms, and still more preferably a methyl group or an ethyl group.

In view of dispersibility of the cyclic siloxane compound [ a ] in the liquid crystal aligning agent, compatibility with the polymer component, and easiness of material acquisition, n is preferably 1 to 10, more preferably 1 to 6, and particularly preferably 1 to 4.

The cyclic siloxane compound [ A ] may further have a photoreactive group. The cyclic siloxane compound [ a ] having a photoreactive group is preferable in that self-crosslinking by thermal reaction of the photoreactive group can be caused and in that light resistance and heat resistance equivalent to those of the crosslinkable group can be obtained when a liquid crystal element is obtained by a polymer stable alignment (Polymer Sustained Alignment, PSA) treatment. The photoreactive group is preferably a group having a carbon-carbon unsaturated bond, and examples thereof include: (meth) acryl, vinylphenyl, vinyl, and the like. Among these, (meth) acryl groups are particularly preferable in terms of high photoreactivity and easiness of self-crosslinking by thermal reaction of photoreactive groups. The photoreactive group is a functional group that does not cause a crosslinking reaction between the photoreactive group introduced into the polymer component and the functional group to crosslink the polymer component by the cyclic siloxane compound [ a ].

When the cyclic siloxane compound [ a ] has a photoreactive group, the crosslinkable group of the cyclic siloxane compound [ a ] is preferably a group having no polymerizable unsaturated bond, and specifically, an epoxy group, an amino group, a cyclic carbonate group, or a hydroxymethyl group is exemplified. In the case where the cyclic siloxane compound [ A ] has a photoreactive group, the number of photoreactive groups is preferably 1 or more, more preferably 2 or more. In order to sufficiently ensure the number of introduced crosslinkable groups, the number of photoreactive groups is preferably 4 or less, more preferably 2 or less.

The molecular weight of the cyclic siloxane compound [ a ] is preferably less than 1000, more preferably 900 or less, and even more preferably 800 or less, in terms of easy dispersion in the liquid crystal aligning agent, better compatibility with the polymer component and solubility in the solvent, and sufficient film strength of the liquid crystal alignment film. In addition, from the viewpoint of suppressing volatilization of the cyclic siloxane compound [ a ], the molecular weight of the cyclic siloxane compound [ a ] is preferably 100 or more, more preferably 200 or more.

Specific examples of the cyclic siloxane compound [ A ] include compounds represented by the following formulae (A-1) to (A-10). As the cyclic siloxane compound [ A ], commercially available ones can be used. Examples of the commercial products include: CS-697, CS-783 (manufactured by Sigma-Aldrich, inc. above), KR-470, X-40-2670, X-40-2678 (manufactured by Siderurgh, inc. above), etc.

[ chemical 3]

[ chemical 4]

(in the formulae (A-1) to (A-7), R is a hydrogen atom or a methyl group, and n is an integer of 0 to 18)

The content ratio of the cyclic siloxane compound [ a ] is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and still more preferably 0.1 parts by mass or more, based on 100 parts by mass of the total amount of the polymer components contained in the liquid crystal aligning agent, in order to sufficiently improve the effect of improving the light resistance and heat resistance of the obtained liquid crystal element. The content of the cyclic siloxane compound [ a ] is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the total amount of the polymer components contained in the liquid crystal aligning agent, in order to suppress film shrinkage during formation of the liquid crystal aligning film. Further, the cyclic siloxane compound [ A ] may be used singly or in combination of two or more.

< other ingredients >

The liquid crystal aligning agent of the present disclosure may contain other compounds than the polymer component and the cyclic siloxane compound [ a ] as required. Specific examples thereof include: epoxy compounds (e.g., N, N, N ', N ' -tetraglycidyl-m-xylylenediamine, 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N ', N ' -tetraglycidyl-4, 4' -diaminodiphenylmethane, N, N-diglycidyl-aminomethylcyclohexane, 1, 6-hexanediol di (meth) acrylate, pentaerythritol tri (meth) acrylate, etc.), functional silane compounds (e.g., 3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, etc.), antioxidants, metal chelating compounds, hardening accelerators, surfactants, fillers, dispersants, photosensitizers, etc. The blending ratio of the other compounds may be appropriately selected according to each compound within a range that does not impair the effects of the present disclosure.

When a compound different from the cyclic siloxane compound [ a ] is used as the crosslinking agent, the content of the compound is preferably 5 mass% or less, more preferably 1 mass% or less, based on the total amount of the cyclic siloxane compound [ a ] contained in the liquid crystal aligning agent.

Solvent component

The liquid crystal aligning agent of the present disclosure is prepared in the form of a solution composition in which a polymer component, a cyclic siloxane compound [ a ], and optionally formulated components are preferably dissolved in an organic solvent. Examples of the organic solvents include: aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and the like. The solvent component may be one of these, or may be a mixed solvent of two or more kinds.

The solvent component may be: a solvent having high solubility and leveling property of the polymer (hereinafter, also referred to as a "first solvent"), a solvent having good wetting expansibility (hereinafter, also referred to as a "second solvent"), and a mixed solvent of these solvents.

Specific examples of the solvent include, for example: n-methyl-2-pyrrolidone, γ -butyrolactone, γ -butyrolactam, N-dimethylformamide, N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, diisobutylketone, ethylene carbonate, propylene carbonate, N-ethyl-2-pyrrolidone, N- (N-pentyl) -2-pyrrolidone, N- (tert-butyl) -2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, 3-butoxy-N, N-dimethylpropionamide, 3-methoxy-N, N-dimethylpropionamide, and the like;

Examples of the second solvent include: ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diacetone alcohol, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, propylene glycol monomethyl ether acetate, 3-methoxy-1-butanol, cyclopentanone, butyl lactate, butyl acetate, methyl methoxy propionate, ethyl ethoxy propionate, isopentyl isobutyrate, propylene glycol diacetate, dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, diisoamyl ether, and the like. Further, one of these may be used alone, but a mixed solvent of the first solvent and the second solvent is preferable.

The solid content concentration (the ratio of the total mass of the components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) in the liquid crystal aligning agent can be appropriately selected in consideration of viscosity, volatility, and the like, and is preferably in the range of 1 to 10 mass%. When the solid content concentration is less than 1 mass%, the film thickness of the coating film is too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10 mass%, the film thickness of the coating film becomes too large, making it difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent increases, and the coatability tends to decrease.

Liquid crystal alignment film and liquid crystal element

The liquid crystal alignment film of the present disclosure is formed from the liquid crystal alignment agent prepared as described. The liquid crystal element of the present disclosure includes a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The operation mode of the liquid crystal In the liquid crystal element is not particularly limited, and is applicable to various modes such as a Twisted Nematic (TN) mode, a super Twisted Nematic (Super Twisted Nematic, STN) mode, a vertical alignment (Vertical Alignment, VA) mode (including a vertical alignment-Multi-domain vertical alignment (Vertical Alignment-Multi-domain Vertical Alignment, VA-MVA) mode, a vertical alignment-pattern vertical alignment (Vertical Alignment-Patterned Vertical Alignment, VA-PVA) mode, an In-Plane Switching (IPS) mode, a fringe field Switching (Fringe Field Switching, FFS) mode, an optically compensated bend (Optically Compensated Bend, OCB) mode, and a PSA mode (Polymer Sustained Alignment). The liquid crystal element can be manufactured by a method including the following steps 1 to 3, for example. In step 1, the substrate is used according to the desired operation mode. Step 2 and step 3 are common in each operation mode.

< step 1: formation of coating film ]

First, a liquid crystal aligning agent is coated on each of a pair of substrates, and the coated surface is preferably heated, thereby forming a coating film on the substrates. As the substrate, for example, a transparent substrate containing the following materials can be used: float glass, sodium glass, and the like; polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, poly (alicyclic olefin) and other plastics. A transparent conductive film provided on one surface of a substrate can be used: comprises tin oxide (SnO) ₂ ) Nesa (Nesa) film (registered trademark of PPG company, U.S.) containing indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) Indium Tin Oxide (ITO) films, and the like. In the case of manufacturing a TN-type, STN-type, or VA-type liquid crystal element, two substrates provided with a patterned transparent conductive film are used. On the other hand, in the case of manufacturing an IPS type or FFS type liquid crystal device, a substrate provided with an electrode patterned into a comb-teeth type and an opposing substrate not provided with an electrode are used. The liquid crystal aligning agent is preferably applied to the substrate on the electrode forming surface by offset printing, flexography, spin coating, roll coater or inkjet printing.

After the liquid crystal alignment agent is applied, preheating (prebaking) is preferably performed for the purpose of preventing dripping of the applied liquid crystal alignment agent, and the like. The pre-baking temperature is preferably 30-200 ℃, and the pre-baking time is preferably 0.25-10 minutes. Thereafter, a calcination (post baking) step is performed for the purpose of completely removing the solvent and, if necessary, thermally imidizing the amic acid structure in the polymer component. The calcination temperature (post-baking temperature) at this time is preferably 80 to 250 ℃, more preferably 80 to 200 ℃. The post-baking time is preferably 5 minutes to 200 minutes. The film thickness of the film thus formed is preferably 0.001 μm to 1 μm.

< step 2: orientation treatment ]

In the case of manufacturing a TN-type, STN-type, IPS-type, or FFS-type liquid crystal device, a process (alignment process) of imparting liquid crystal alignment ability to the coating film formed in step 1 is performed. Thus, the liquid crystal alignment film is obtained by imparting the liquid crystal molecules with alignment ability to the coating film. As the orientation treatment, the following treatment can be used: a rubbing treatment in which a coating film formed on a substrate is rubbed in a predetermined direction by a roller around which a cloth containing, for example, fibers such as nylon (nylon), rayon (rayon), cotton (cotton) or the like is wound, a photo-alignment treatment in which a coating film formed on a substrate is irradiated with light to impart liquid crystal alignment ability to the coating film, or the like. On the other hand, in the case of manufacturing a Vertical Alignment (VA) type liquid crystal element, the coating film formed in the above step 1 may be directly used as a liquid crystal alignment film, but in order to further improve the liquid crystal alignment ability, the coating film may be subjected to an alignment treatment. A liquid crystal alignment film suitable for a vertical alignment type liquid crystal element can also be suitably used for a PSA type liquid crystal element.

In the photo-alignment treatment, light irradiation may be performed by the following method or the like: a method of irradiating a coating film after the post-baking step, a method of irradiating a coating film after the pre-baking step and before the post-baking step, and a method of irradiating a coating film during heating of a coating film in at least any one of the pre-baking step and the post-baking step. As the radiation to be irradiated to the coating film, for example, ultraviolet rays and visible rays including light having a wavelength of 150nm to 800nm can be used. Preferably ultraviolet rays containing light having a wavelength of 200nm to 400 nm. In the case where the radiation is polarized, the radiation may be linearly polarized or partially polarized. In the case where the radiation used is linearly polarized light or partially polarized light, the irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these directions. The irradiation direction in the case of unpolarized radiation is set to be an oblique direction.

Examples of the light source to be used include: low pressure waterSilver lamps, high pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, excimer lasers, and the like. The irradiation amount of the radiation to the substrate surface is preferably 400J/m ² ～50,000J/m ² More preferably 1,000J/m ² ～20,000J/m ² . After the light irradiation for imparting orientation ability, a treatment of cleaning the substrate surface with, for example, water, an organic solvent (for example, methanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, or the like) or a mixture of these, or a treatment of heating the substrate may be performed.

< step 3: construction of liquid Crystal cell-

As described above, two substrates on which a liquid crystal alignment film is formed are prepared, and a liquid crystal cell is manufactured such that liquid crystal is disposed between the two substrates adjacent to the liquid crystal alignment film. In manufacturing a liquid crystal cell, for example, the following methods can be mentioned: the method of disposing two substrates facing each other with a gap therebetween so that the liquid crystal alignment films face each other, bonding the peripheral portions of the two substrates with a sealant, and filling a cell gap surrounded by the substrate surface and the sealant with liquid crystal and sealing the filling hole is a method using a liquid crystal Drop Fill (ODF) method or the like. For example, an epoxy resin containing a hardener and alumina balls as spacers (spacers) can be used as the sealant. The liquid crystal includes nematic liquid crystal and smectic liquid crystal, and among them, nematic liquid crystal is preferable. In the PSA mode, after the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light in a state where a voltage is applied between conductive films provided on a pair of substrates.

In the case of manufacturing a PSA-type liquid crystal element, a liquid crystal cell is constructed in the same way as described above, except that liquid crystal is injected or dropped together with a photopolymerizable monomer between a pair of substrates having a conductive film. As the photopolymerizable monomer, a conventionally known compound can be used. Preferably a polyfunctional (meth) acrylic monomer. Thereafter, the liquid crystal cell is irradiated with light in a state where a voltage is applied between the conductive films provided on the pair of substrates. The voltage applied here may be, for example, 5V to 50V dc or ac. In addition, as the irradiated light, for example, it is possible to useUltraviolet and visible rays including light having a wavelength of 150nm to 800 nm. Of these, ultraviolet rays containing light having a wavelength of 300nm to 400nm are preferable. Examples of the light source for irradiating light include a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, and an excimer laser. The irradiation amount of light is preferably 1,000J/m ² ～200,000J/m ² More preferably 1,000J/m ² ～150,000J/m ² 。

Then, a polarizing plate is attached to the outer surface of the liquid crystal cell as needed, thereby producing a liquid crystal element. The polarizing plate may be exemplified by: a polarizing film called an "H film" in which iodine is absorbed while polyvinyl alcohol is stretched and oriented with a cellulose acetate protective film is sandwiched between the obtained polarizing plates or a polarizing plate including the H film itself.

The liquid crystal element of the present disclosure is effectively applicable to various applications, for example, to various display devices such as a timepiece, a portable game machine, a word processor, a notebook computer, a car navigation system, a video camera, a personal digital assistant (Personal Digital Assistant, PDA), a digital camera, a mobile phone, a smart phone, various monitors, a liquid crystal television, an information display, and the like, or to a light adjusting film, a phase difference film, and the like.

Examples

Hereinafter, specific description will be given by way of examples, but the present disclosure is not limited to the following examples.

In the following examples, the solution viscosity, weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw/Mn), imidization ratio and epoxy equivalent of the polymer were measured by the following methods.

< solution viscosity of Polymer >

The solution viscosity of the polymer was measured using an E-type viscometer at 25 ℃.

< weight average molecular weight, number average molecular weight and molecular weight distribution >

Mw and Mn were measured by Gel Permeation Chromatography (GPC) under the following conditions. The molecular weight distribution (Mw/Mn) was calculated from the Mw and Mn obtained.

The device comprises: GPC-101 of Showa electrician (Strand) "

GPC column: "GPC-KF-801", "GPC-KF-802", "GPC-KF-803" and "GPC-KF-804" manufactured by Shimadzu GLC (SHIMADZU GLC) (Strand) are connected

Mobile phase: tetrahydrofuran (THF)

Column temperature: 40 DEG C

Flow rate: 1.0 mL/min

Sample concentration: 1.0 mass%

Sample injection amount: 100 mu L

A detector: differential refractometer

Standard substance: monodisperse polystyrene

< imidization Rate of Polymer >

The polyimide-containing solution was poured into pure water, and the obtained precipitate was dried under reduced pressure at room temperature, and then dissolved in deuterated dimethyl sulfoxide, and measured at room temperature using tetramethylsilane as a reference substance ¹ H-NMR. According to the obtained ¹ The H-NMR spectrum was used to determine the imidization rate by using the following formula (E-1).

Imidization ratio (%) = (1-a) ¹ /A ² ×α)×100…(E-1)

(in the formula (E-1), A ¹ For the peak area of protons derived from NH groups, which appear in the vicinity of chemical shift 10ppm, A ² For the peak area derived from other protons, α is the number ratio of other protons to 1 proton of NH group of the precursor of the polymer (polyamic acid). )

< epoxy equivalent >

The epoxy equivalent is measured by the hydrochloric acid-methyl ethyl ketone method described in Japanese Industrial Standard (Japanese Industrial Standards, JIS) C2105.

The abbreviations of the compounds used in the following examples are shown below. For convenience, the "compound represented by the formula (X)" may be simply referred to as "compound (X)".

Cyclic siloxane Compound [ A ]

[ chemical 5]

In addition to the cyclic siloxane compounds [ A ]

[ chemical 6]

< Synthesis of Polymer >

Synthesis example 2-1: synthesis of polyimide

77g (0.34 mol) of 2,3, 5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride, 19g (0.18 mol) of p-phenylenediamine as diamine, and 27g (0.18 mol) of 3, 5-diaminobenzoic acid were dissolved in 1,260g of N-methyl-2-pyrrolidone (NMP) and reacted at room temperature for 6 hours, thereby obtaining a polyamic acid-containing solution. A small amount of the obtained polyamic acid solution was collected and concentrated under reduced pressure to obtain a solution having a concentration of 10% by mass, and the solution viscosity was found to be 80 mPas. Then, 600g of NMP was added to the polyamic acid solution obtained, 136g of pyridine and 105g of acetic anhydride were added, and the dehydration ring-closure reaction was performed at 110℃for 4 hours. After the dehydration ring-closure reaction, the solvent in the system was replaced with new γ -butyrolactone, and then concentrated, whereby 600g of a solution containing 20 mass% of a polyimide polymer (PI-1) having an imidization ratio of about 85% was obtained. A small amount of the solution was separated, and gamma-butyrolactone was added thereto to prepare a solution having a concentration of 6.0% by mass, and the solution viscosity was measured to be 22 mPas.

Synthesis example 2-2: synthesis of Polyamic acid

13.8g (0.070 mol) of 1,2,3, 4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 16.3g (0.0769 mol) of 2,2 '-dimethyl-4, 4' -diaminobiphenyl as diamine were dissolved in 170g of NMP and reacted at 25℃for 3 hours, whereby a solution containing 10 mass% of polyamic acid (referred to as "polymer (PA-1)") was obtained.

Synthesis examples 2 to 3: synthesis of styrene-maleimide-based copolymer

5.00g (8.6 mmol) of the compound (MI-1) as a polymerization monomer, 0.64g (4.3 mmol) of 4-vinylbenzoic acid, 2.82g (13.0 mmol) of 4- (2, 5-bisoxy-3-pyrrolin-1-yl) benzoic acid, 3.29g (17.2 mmol) of 4- (glycidoxymethyl) styrene, 0.31g (1.3 mmol) of 2,2' -azobis (2, 4-dimethylpentanenitrile) as a radical polymerization initiator, 0.52g (2.2 mmol) of 2, 4-diphenyl-4-methyl-1-pentene as a chain transfer agent, and 25mL of tetrahydrofuran as a solvent were charged into a 100mL two-necked flask under nitrogen, and polymerization was performed at 70℃for 5 hours. After reprecipitation in n-hexane, the precipitate was filtered and dried under vacuum at room temperature for 8 hours, whereby a polymer (StMI-A) as a styrene-maleimide-based copolymer was obtained. The weight average molecular weight Mw measured by conversion to polystyrene by GPC was 30000 and the molecular weight distribution Mw/Mn was 2.

Synthesis examples 2 to 4: synthesis of styrene-maleimide-based copolymer

Synthesis examples 2 to 3 were conducted in the same manner as in Synthesis examples 2 to 3, except that Compound (MI-2) was used as a polymerization monomer instead of Compound (MI-1). After reprecipitation in n-hexane, the precipitate was filtered and dried under vacuum at room temperature for 8 hours, whereby a polymer (StMI-B) as a styrene-maleimide-based copolymer was obtained. The weight average molecular weight Mw measured by conversion to polystyrene by GPC was 25000 and the molecular weight distribution Mw/Mn was 2.

Synthesis examples 2 to 5: synthesis of epoxy-containing Polyorganosiloxanes

100.0g of 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 500g of methyl isobutyl ketone and 10.0g of triethylamine were placed in a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser, and the mixture was stirred at room temperature. After 100g of deionized water was added thereto dropwise from the addition funnel over 30 minutes, the mixture was refluxed and reacted at 80℃for 6 hours. After the completion of the reaction, the organic layer was taken out, washed with an aqueous solution of 0.2 mass% ammonium nitrate until the washed water became neutral, and then the solvent and water were distilled off under reduced pressure, whereby an epoxy group-containing polyorganosiloxane was obtained as a viscous transparent liquid. The epoxy equivalent of the epoxy group-containing polyorganosiloxane (referred to as "polyorganosiloxane (PS-1)") was measured and found to be 186 g/equivalent.

< preparation and evaluation of liquid Crystal alignment agent >

Example 1

1. Preparation of liquid Crystal alignment agent (AL-1)

To the solution containing 100 parts by mass of the polymer (PI-1) obtained in synthesis example 2-1, 10 parts by mass of the polymer (StMI-a) obtained in synthesis example 2-3, 2 parts by mass of the compound (a-1-1) (trade name "KR-470", manufactured by the company siegesbeckia (Shinetsu Silicone)), and NMP and Butyl Cellosolve (BC) as solvents were added to prepare a solution having a solvent composition of NMP/bc=50/50 (mass ratio) and a solid content concentration of 4.0 mass%. The solution was filtered using a filter having a pore size of 1 μm, thereby preparing a liquid crystal aligning agent (AL-1).

2. Manufacture of light vertical type liquid crystal display element

The prepared liquid crystal aligning agent (AL-1) was coated on the transparent electrode surface of the glass substrate with the transparent electrode containing an ITO film using a rotator, and pre-baked using a hot plate at 80 ℃ for 1 minute. Thereafter, the resultant film was heated at 230℃for 1 hour in an oven in which nitrogen gas was substituted for the inside of the chamber, to thereby form a coating film having a film thickness of 0.1. Mu.m. Then, using an Hg-Xe lamp and a Glan-Taylor prism, polarized ultraviolet rays 1,000J/m including an open line of 313nm are irradiated to the coated film surface from a direction inclined by 40 DEG from the substrate normal ² And imparts liquid crystal aligning ability to the coating film. The same operation was repeated to produce a pair (two sheets) of substrates having liquid crystal alignment films.

An epoxy adhesive containing alumina spheres having a diameter of 3.5 μm was applied by screen printing to the outer periphery of the surface having the liquid crystal alignment film of one of the pair of substrates having the liquid crystal alignment film formed thereon. Next, the surfaces of the liquid crystal alignment films of the pair of substrates were opposed to each other, and the adhesive was thermally cured at 150 ℃ for 1 hour so that the optical axes of ultraviolet rays of the respective substrates became antiparallel to each other in the projection direction of the substrate surfaces. Then, a gap between the substrates was filled with negative-type liquid crystal (MLC-6608 manufactured by Merck) from a liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to remove the flow alignment at the time of liquid crystal injection, the liquid crystal was heated at 130 ℃ and then cooled to room temperature gradually, thereby obtaining a liquid crystal cell. Then, the polarizing plates were bonded to both outer surfaces of the substrate so that the polarizing directions of the polarizing plates were orthogonal to each other and an angle of 45 ° was formed with respect to the projection direction of the ultraviolet ray of the liquid crystal alignment film on the substrate surface, thereby manufacturing a light-vertical liquid crystal display element.

3. Evaluation of liquid Crystal display element

The above-described operations were repeated to manufacture a plurality of liquid crystal display elements, and the following evaluations of heat resistance and light resistance were performed. Further, the evaluation of heat resistance and light resistance was performed using different liquid crystal display elements.

[ evaluation of Heat resistance ]

In the above-described manufactured vertical light type liquid crystal display element, after a voltage of 5V was applied at 60 ℃ for an application time of 60 microseconds and a span (span) of 167 milliseconds, a voltage holding ratio after 167 milliseconds from the release of the application was measured, and this was set as an initial voltage holding ratio Arf [% ]. Then, after the liquid crystal cell was left to stand in an oven at 100 ℃ for 1,000 hours to impart a thermal stress, the voltage holding ratio was measured again under the same conditions, and was set to be the post-thermal stress voltage holding ratio Atm [% ]. The amount of decrease α [% ] (α=arf-Atm) of the voltage retention Atm after thermal stress relative to the initial voltage retention Arf was calculated, and the heat resistance of the liquid crystal display element was evaluated based on the amount of decrease α. The case where the decrease amount α is 1% or less is evaluated as "extremely good (excellent)", the case where the decrease amount α exceeds 1% and 2% or less is evaluated as "good (o)", the case where the decrease amount α exceeds 2% and 3% or less is evaluated as "heat resistance (Δ)", and the case where the decrease amount α exceeds 3% is evaluated as "poor (x)". As a result, in the examples, the heat resistance was evaluated as "extremely good (verygood)". The voltage holding ratio measuring device was VHR-1 manufactured by TOYO technology (Strand).

[ evaluation of light resistance ]

The voltage holding ratio of the manufactured optically perpendicular liquid crystal display element was measured under the same conditions as those for evaluation of heat resistance, and was set to the initial voltage holding ratio Arf [% ]. Then, the liquid crystal display element was left standing at a distance of 5cm under a 0 watt white fluorescent lamp, light was irradiated for 1,000 hours to apply optical stress, and then the voltage holding ratio was measured again under the same conditions, and this was set as the post-optical stress voltage holding ratio Agt [% ]. The reduction amount β [% ] (β=arf-Agt) of the voltage holding ratio Agt after the optical stress relative to the initial voltage holding ratio Arf was calculated, and the light resistance of the liquid crystal display element was evaluated based on the reduction amount β. The case where the decrease amount β is 1% or less is evaluated as "extremely good (excellent)" in light resistance, the case where the decrease amount β exceeds 1% and 2% or less is evaluated as "good (o)" in light resistance, the case where the decrease amount β exceeds 2% and 3% or less is evaluated as "ok (Δ)" in light resistance, and the case where the decrease amount β exceeds 3% is evaluated as "poor (x)" in light resistance. As a result, in the examples, the light resistance was evaluated as "extremely good (verygood)".

Examples 2 to 9 and comparative examples 1, 2, 4 and 6

Liquid crystal alignment agents were prepared in the same solvent composition and solid content concentration as in example 1, except that the blending composition was changed as shown in tables 1 to 3 below. In addition, a light vertical type liquid crystal display element was produced in the same manner as in example 1 using each liquid crystal aligning agent, and various evaluations were performed. These results are shown in tables 1 to 3 below.

Example 10

1. Preparation of liquid Crystal alignment agent (AL-10)

A liquid crystal aligning agent (AL-10) was prepared in the same solvent composition and solid content concentration as in example 1, except that the polymer used was changed to 100 parts by mass of the solution containing the polymer (PA-1) obtained in Synthesis example 2-2 and 5 parts by mass of the polymer (StMI-B) obtained in Synthesis example 2-4.

2. Preparation of liquid Crystal composition

To 10g of nematic liquid crystal (MLC-6608 manufactured by Merck (Merck)) were added 5 mass% of the liquid crystalline compound represented by the formula (L1-1) and 0.3 mass% of the photopolymerizable compound represented by the formula (L2-1) and mixed, whereby a liquid crystal composition LC1 was obtained.

Manufacturing of PSA-type liquid Crystal display element

The prepared liquid crystal alignment agent (AL-10) was applied to each electrode surface of two glass substrates each having a conductive film including an ITO electrode using a liquid crystal alignment film printer (manufactured by japan photo printing), heated (pre-baked) on a hot plate at 80 ℃ for 2 minutes to remove the solvent, and then heated (post-baked) on a hot plate at 230 ℃ for 10 minutes to form a coating film having an average film thickness of 0.06 μm. For these coating films, after ultrasonic cleaning in ultrapure water for 1 minute, drying was performed in a clean oven at 100 ℃ for 10 minutes, thereby obtaining a pair (two sheets) of substrates having liquid crystal alignment films. The pattern of the electrode used is the same type of pattern as the electrode pattern in the PSA mode.

Then, an epoxy adhesive agent containing alumina balls having a diameter of 5.5 μm was applied to the outer edge of the surface of one of the pair of substrates having the liquid crystal alignment film, and then the adhesive agent was cured by being superimposed and pressure-bonded so that the liquid crystal alignment film surfaces face each other. Then, the prepared liquid crystal composition LC1 was filled between a pair of substrates from a liquid crystal injection port, and then the liquid crystal injection port was sealed with an acrylic photo-curing adhesive, thereby manufacturing a liquid crystal cell. Thereafter, an alternating current of 10V at a frequency of 60Hz was applied between the conductive films of the liquid crystal cell, and in a liquid crystal-driven state, an ultraviolet irradiation device using a metal halide lamp as a light source was used at 100,000J/m ² Is irradiated with ultraviolet rays. The irradiation amount is a value measured using a light meter measuring with a wavelength of 365nm as a reference. Thereafter, the polarizing plates were bonded to both outer surfaces of the substrate so that the polarizing directions of the polarizing plates were perpendicular to each other and an angle of 45 ° was formed with respect to the projection direction of the ultraviolet ray of the liquid crystal alignment film on the substrate surface, thereby manufacturing a PSA type liquid crystal display element.

4. Evaluation of liquid Crystal display element

The above-described operations were repeated to produce a plurality of liquid crystal display elements, and heat resistance and light resistance were evaluated in the same manner as in example 1. As a result, in the examples, the heat resistance and the light resistance were evaluated as "extremely good (verygood)".

Examples 11 to 13, and comparative examples 3 and 5

Liquid crystal aligning agents were prepared with the same solvent composition and solid content concentration as in example 10, except that the blending composition was changed as shown in tables 2 and 3 below. A PSA-type liquid crystal display element was produced in the same manner as in example 10 using each liquid crystal aligning agent, and various evaluations were performed in the same manner as in example 1. These results are shown in tables 2 and 3 below.

TABLE 1

TABLE 2

TABLE 3

In tables 1 to 3, "-" indicates that the column compound is not used. The abbreviations of the compounds are described below.

A-1-1: trade name "KR-470", manufactured by Sitezui Liguang (Shinetsu Silicone) company (the compound represented by the formula (A-1-1))

A-2-1: trade name "CS-697", manufactured by Sigma Aldrich (Sigma-Aldrich) company (Compound represented by the formula (A-2-1))

A-3-1: trade name "CS-783", manufactured by Sigma Aldrich (Sigma-Aldrich) company (Compound represented by the formula (A-3-1))

C-1: trade name "X-40-2669", manufactured by Sitezui Liguang (Shinetsu Silicone) company (Compound represented by the above formula (C-1))

C-2: the polyorganosiloxane (PS-1) of Synthesis examples 2-5

C-3: n, N, N ', N ' -tetraglycidyl-4, 4' -diaminodiphenylmethane (Compound represented by the formula (C-3))

From the above results, in examples 1 to 13, in which a liquid crystal aligning agent containing a cyclic siloxane compound [ a ] as a crosslinking agent was used, the evaluation of heat resistance and light resistance of the liquid crystal display element was "extremely good (excellent)" or "good (o)".

In contrast, in comparative examples 4 and 5, which have the same compositions as those of the liquid crystal aligning agents of examples 1 to 3 and examples 10 to 13, except that the cyclic siloxane compound [ a ] was not contained, both the light resistance and the heat resistance were inferior to those of examples.

In comparative example 1 in which the compound (C-1) which is a polyfunctional siloxane compound having a chain structure was used in place of the cyclic siloxane compound [ a ], the light resistance was inferior to that of examples (examples 1 to 3), and the heat resistance was also inferior to that of examples 1 and 2. In comparative examples 2 and 3 in which polyorganosiloxane (PS-1) was used instead of the cyclic siloxane compound [ A ], both the light resistance and the heat resistance were inferior to those of examples (examples 1 to 3 and examples 10 to 13).

In comparative example 6 using the conventionally used compound (C-3) as a crosslinking agent, both the light resistance and the heat resistance were inferior to those of the examples.

From these results, it is found that a liquid crystal element excellent in heat resistance and light resistance can be obtained by using the cyclic siloxane compound [ A ] as a crosslinking agent.

Claims

1. A liquid crystal aligning agent comprising: a polymer component; and a cyclic siloxane compound [ A ] having a crosslinkable group, wherein

The polymer component is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and a polymer having a structural unit derived from a monomer having a polymerizable unsaturated bond,

the cyclic siloxane compound [ A ] is a compound represented by the following formula (1),

in the formula (1), R ¹ ～R ⁶ Each independently is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms; wherein R is ¹ ～R ⁶ 3 to 4 of the groups are monovalent organic groups having a crosslinkable group; n is an integer of 1 to 18; when n is 2 or more, a plurality of R ¹ The R's may be the same or different from each other ² May be the same as or different from each other,

the crosslinking group is an oxirane group or an oxetanyl group,

the monovalent organic group having a crosslinkable group is a group represented by the following formula (2),

* ¹ -R ⁷ -X ¹ …(2)

In the formula (2), R ⁷ Is an alkanediyl group having 1 to 10 carbon atoms or a divalent group having-O-or-S-between carbon-carbon bonds of an alkanediyl group having 2 to 20 carbon atoms, X ¹ Is a monovalent group having an oxirane group or an oxetanyl group ¹ Representing a bond to a silicon atom.

2. The liquid crystal aligning agent according to claim 1, which contains two or more kinds of polymers as the polymer component.

3. A liquid crystal alignment film formed using the liquid crystal alignment agent according to claim 1 or 2.

4. A liquid crystal element comprising the liquid crystal alignment film according to claim 3.

5. A method of manufacturing a liquid crystal element, comprising:

a step of forming a photo-alignment film by applying the liquid crystal alignment agent according to claim 1 or 2 to each of the substrate surfaces of a pair of substrates and irradiating the substrate surfaces with light; and

and a step of disposing the pair of substrates on which the photo-alignment films are formed so as to face each other with the liquid crystal layer interposed therebetween, thereby constructing a liquid crystal cell.

6. A method of manufacturing a liquid crystal element, comprising:

a step of forming a coating film by applying the liquid crystal aligning agent according to claim 1 or 2 to each of the conductive films of a pair of substrates having the conductive films;

A step of disposing the pair of substrates on which the coating film is formed, with a liquid crystal layer interposed therebetween, so that the coating film faces each other, thereby constructing a liquid crystal cell; and

and a step of irradiating the liquid crystal cell with light in a state where a voltage is applied between the conductive films.