CN114502609A - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal element - Google Patents

Abstract

The liquid crystal aligning agent contains a polymer (A) having a structural unit derived from at least one monomer selected from the group consisting of a compound represented by formula (1) and a compound represented by formula (2). In the formula, R¹And R²Represents R¹And R²One is a monovalent group having a polymerizable group, and the other isIs a hydrogen atom or a monovalent organic group, or R¹And R²Are bonded to each other to R¹And R²The bonded nitrogen atoms together form a ring structure. Wherein the ring structure has a polymerizable carbon-carbon unsaturated bond. A. the¹Is a monovalent organic radical, A²Is a hydroxyl group or a monovalent organic group. Satisfies 0 ≦ n1+ n2 ≦ 8.

Description

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

[ CROSS-REFERENCE TO RELATED APPLICATIONS ]

The application is based on Japanese patent application No. 2019-187165 filed on 10.10.2019, and the description content thereof is cited in the application.

Technical Field

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

Background

The liquid crystal element includes a liquid crystal alignment film that aligns liquid crystal molecules in a certain direction. In general, a liquid crystal alignment film is formed by: the substrate is coated with a liquid crystal aligning agent in which a polymer component is dissolved in an organic solvent, and preferably heated. As a polymer component of the liquid crystal aligning agent, polyamic acid or soluble polyimide has been used since now in terms of excellent mechanical strength, liquid crystal aligning property, and affinity with liquid crystal.

As a method for imparting liquid crystal aligning ability to a polymer film formed of a liquid crystal aligning agent, a photo-alignment method has been proposed as a technique replacing a rubbing method. The photo-alignment method is as follows: the orientation of the liquid crystal is controlled by applying anisotropy to a radiation-sensitive organic thin film formed on a substrate by irradiating the film with polarized or unpolarized radiation.

As a liquid crystal aligning agent for forming a liquid crystal alignment film by a photo-alignment method, there is provided a liquid crystal aligning agent containing a polymer having a main skeleton different from that of a polyamic acid and a soluble polyimide (for example, see patent document 1 or patent document 2). Patent document 1 discloses a photo-alignment composition containing a reaction product of a polymer having a maleic anhydride structure and a primary amine compound having a photo-alignment group. Patent document 2 discloses a photo-alignment composition including a first polymer having a main chain of poly (maleimide) or poly (maleimide-styrene) and a side chain to which a photosensitive group is introduced, and a second polymer having a long-chain alkyl group in the side chain.

Documents of the prior art

Patent document

Patent document 1: korean laid-open patent No. 2015-138548

Patent document 2: japanese patent No. 2962473

Disclosure of Invention

Problems to be solved by the invention

The angle (pretilt angle) formed between the long axis of the liquid crystal molecule and the substrate surface greatly affects the display characteristics of the liquid crystal element. The present inventors have made the following attempts: the alignment control of the liquid crystal is performed so that the long axes of the liquid crystal molecules are inclined at an appropriate angle with respect to the vertical direction (for example, in a vertical alignment type liquid crystal element, the pretilt angle is 89 degrees or less), thereby obtaining a liquid crystal element finer than before. However, it is known that when a liquid crystal alignment film is formed using the alignment film material of patent document 1 or patent document 2, the long axis of the liquid crystal molecules cannot be sufficiently inclined with respect to the vertical direction, and the pretilt angle is higher than a desired angle.

In addition, in recent years, in a heating step at the time of film formation, it is sometimes required to use a low boiling point solvent as a solvent component of the liquid crystal aligning agent for the purpose of enabling low temperature calcination or the like. When the polymer component is not uniformly dissolved in the solvent, uneven coating may occur in the liquid crystal alignment film formed on the substrate, and a flat film may not be formed (coating uniformity is poor). In this case, the product yield may be reduced, or display performance such as liquid crystal alignment properties and electrical characteristics may be affected.

Further, when the liquid crystal alignment film is formed by low-temperature baking, the pretilt angle of the liquid crystal alignment film may deviate from the pretilt angle of the liquid crystal alignment film obtained by conventional high-temperature baking (for example, heat treatment at a temperature of about 230 to 250 ℃). Such a variation in pretilt angle due to a difference in heating temperature at the time of film formation (hereinafter, also referred to as "post-baking margin") affects the display quality of the liquid crystal element, and therefore is desirably as small as possible.

The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide a liquid crystal aligning agent capable of forming a liquid crystal alignment film having good coating uniformity and excellent pretilt angle characteristics.

Means for solving the problems

The present inventors have found that the above problems can be solved by using a polymer having a specific structure as a polymer component of a liquid crystal aligning agent. Specifically, according to the present disclosure, the following means are provided.

[1] A liquid crystal aligning agent comprising a polymer (A) having a structural unit derived from at least one monomer selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2),

[ solution 1]

(in the formulae (1) and (2), R¹And R²Represents R¹And R²One is a monovalent group having a polymerizable group, the other is a hydrogen atom or a monovalent organic group, or R¹And R²Are bonded to each other to R¹And R²A ring structure formed by the bonded nitrogen atoms; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; a. the¹Is a monovalent organic radical, A²Is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently integers satisfying 0 ≦ n1+ n2 ≦ 8).

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

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

[4] A polymer having a structural unit derived from at least one monomer selected from the group consisting of the compound represented by the formula (1) and the compound represented by the formula (2).

[5] A compound represented by the formula (1).

[6] A compound represented by the formula (2).

ADVANTAGEOUS EFFECTS OF INVENTION

By containing the polymer (a) in the liquid crystal aligning agent, a liquid crystal aligning agent having good coating uniformity can be obtained. In addition, by forming a liquid crystal alignment film using the liquid crystal aligning agent, the tilt angle of liquid crystal molecules with respect to the vertical direction can be sufficiently increased, and the deviation of the pretilt angle due to the difference in heating temperature at the time of film formation can be reduced. That is, according to the liquid crystal aligning agent, a liquid crystal alignment film having excellent pretilt angle characteristics can be formed.

Detailed Description

The following describes matters related to the present disclosure in detail.

Liquid crystal aligning agent

The disclosed liquid crystal aligning agent contains a polymer (A) having a structural unit U1 derived from at least one monomer (R1) selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2).

[ solution 2]

(in the formulae (1) and (2), R¹And R²Represents R¹And R²One of them is a hydrogen atom or a monovalent organic group, and the other is a monovalent group having a polymerizable group, or R¹And R²Are bonded to each other to R¹And R²A ring structure formed by the bonded nitrogen atoms; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; a. the¹Is a monovalent organic radical, A²Is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0 ≦ n1+ n2 ≦ 8)

< Polymer (A) >

(structural unit U1)

In the above formulae (1) and (2), A is¹And A²Examples of the monovalent organic group include: a C1-40 monovalent hydrocarbon group, at least one methylene group of the hydrocarbon group being substituted by-O-, -CO-, -COO-, -NR¹⁰-or-CONR¹⁰- (wherein, R)¹⁰Hydrogen atom or monovalent hydrocarbon group) (hereinafter also referred to as "group α"), monovalent hydrocarbon group having 1 to 40 carbon atoms, or group in which at least one hydrogen atom of group α is substituted with a fluorine atom or a cyano group.

Here, in the present specification, the term "hydrocarbon group" is intended to include chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The "chain hydrocarbon group" refers to a straight-chain hydrocarbon group and a branched hydrocarbon group having no cyclic structure in the main chain and consisting of only a chain structure. The polymer may be saturated or unsaturated. The "alicyclic hydrocarbon group" refers to a hydrocarbon group having only an alicyclic hydrocarbon structure as a ring structure and not having an aromatic ring structure. The alicyclic hydrocarbon may not be composed of only the alicyclic hydrocarbon structure, but may have a chain structure in a part thereof. The "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. In addition, the structure may not necessarily be composed of only an aromatic ring structure, and may include a chain structure or an alicyclic hydrocarbon structure in a part thereof.

In the case of preparing the liquid crystal aligning agent of the present disclosure into a polymer composition for forming a photo-alignment film, a in the formula (1)¹Preferably a monovalent group having a photo-alignment group. A. the¹The photo-alignment group is preferably a functional group that imparts anisotropy to the film by photoisomerization reaction, photodimerization reaction, photo Fries rearrangement (photo Fries rearrangement) reaction, or photolysis reaction by light irradiation.

In A¹In the case of having a photo-alignment group, specific examples of the photo-alignment 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 (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 phenylbenzoate-containing group containing phenylbenzoate or a derivative thereof as a basic skeleton, a cyclobutanyl group containing cyclobutanylA cyclobutane-containing structure having an alkane or a derivative thereof as a basic skeleton, and the like. Among these, the photo-alignment group is preferably a group containing a cinnamic acid structure in terms of high photosensitivity. Specifically, a group containing a cinnamic acid structure represented by the following formula (3) as a basic skeleton is particularly preferable.

[ solution 3]

(in the formula (3), R¹¹And R¹²Each independently represents a hydrogen atom, a fluorine atom, a cyano group, an alkyl group having 1 to 3 carbon atoms or a fluoroalkyl group having 1 to 3 carbon atoms, R¹³An alkyl group having 1 to 10 carbon atoms which may have a fluorine atom or a cyano group, an alkoxy group having 1 to 10 carbon atoms which may have a fluorine atom or a cyano group, a fluorine atom, or a cyano group; a is an integer of 0-4; when a is 2 or more, a plurality of R¹³Are identical radicals or different radicals; "+" indicates a bond)

In the structure represented by the formula (3), R is preferably used in order to further improve photoreactivity¹¹And R¹²Are each a hydrogen atom, or one is a hydrogen atom and the other is preferably R¹²) Is an alkyl group having 1 to 3 carbon atoms.

R¹³Preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. a is preferably 0 to 2, more preferably 0 or 1.

In terms of more suitably controlling the pretilt angle of the liquid crystal element obtained, it is preferable that one of the two bonds "×" in the formula (3) is bonded to a group having at least one of one or more benzene rings and cyclohexane rings in total, and more preferably to a group having at least one of two or more benzene rings and cyclohexane rings in total. Specifically, it is preferable that one of the two bonds "×" in the formula (3) is a bond to a group represented by the following formula (4).

[ solution 4]

(in the formula (4), X¹A single bond, an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom, a sulfur atom, -CH-, -NH-, -COO-, or-OCO-, a single bond, an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom, a sulfur atom, or-NH-, when bonded to a phenyl group in the formula (3); r¹⁴Is a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cyclohexylene group, R¹⁵Is a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cyclohexylene group. R¹⁶A phenyl group or a cyclohexyl group, or a monovalent group in which at least one hydrogen atom of the phenyl group or the cyclohexyl group is substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group, a substituted alkoxy group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group, a fluorine atom, or a cyano group; r is an integer of 0 to 3; when R is 2 or more, a plurality of R¹⁵Are identical radicals or different radicals; "+" indicates a bond)

In the formula (4), the substituent bonded to the ring of the phenylene group and the cyclohexylene group is preferably an alkyl group having 1 to 3 carbon atoms, a fluorine atom, or a cyano group. r is preferably 0 or 1. R¹⁶Preferably a monovalent group in which at least one hydrogen atom of a phenyl group or a cyclohexyl group is substituted with a substituted or unsubstituted alkyl group or alkoxy group. In this case, the substituted or unsubstituted alkyl group or alkoxy group is preferably a group having 2 or more carbon atoms, and more preferably 3 or more carbon atoms.

A in the above formulae (1) and (2) is a group having a higher solubility in a solvent²Preferably a hydroxyl group OR a group "-OR¹⁷"(wherein, R is¹⁷A monovalent hydrocarbon group having 1 to 10 carbon atoms), more preferably a hydroxyl group or an alkoxy group having 1 to 3 carbon atoms, and still more preferably a hydroxyl group or a methoxy group.

The monomer (R1) has a structure comprising-CO-N (A)¹) -a saturated heterocycle of CO-, or a structure obtained by ring-opening of the saturated heterocycle. N1+ n2 in the above formulae (1) and (2) is preferably 1 or more, more preferably 1 or moreIs an integer of 1 to 6. The monomer (R1) is preferably an open ring body of the compound represented by the formula (2), that is, the compound represented by the formula (1), in terms of obtaining a polymer having more excellent solubility in a solvent.

In the above formulae (1) and (2), R¹And R²Represents R¹And R²One is a monovalent group having a polymerizable group, the other is a hydrogen atom or a monovalent organic group, or R¹And R²Are bonded to each other to R¹And R²A ring structure (hereinafter, also referred to as "ring structure X") composed of the bonded nitrogen atoms. Wherein the ring structure X has a polymerizable carbon-carbon unsaturated bond in the ring. R¹And R²The polymerizable group in one of them and the polymerizable carbon-carbon unsaturated bond in the ring structure X may be selected depending on the main skeleton of the polymer (a). The polymer (a) may be a polymer produced by addition polymerization of monomers (hereinafter, also referred to as "addition polymer (a 1)") or a polymer produced by polycondensation of monomers (hereinafter, also referred to as "polycondensate (a 2)").

(addition Polymer)

The addition polymer (a1) is not particularly limited as long as it is a polymer obtained using a monomer having a group containing a carbon-carbon unsaturated bond as a polymerizable group. The addition polymer (a1) can be obtained by addition polymerization using a monomer (R1) whose polymerizable group is a group containing a carbon-carbon unsaturated bond.

Among the monomers (R1) used in the synthesis of the addition polymer (A1), R is¹And R²When one of them is a monovalent group having a polymerizable group and the other is a hydrogen atom or a monovalent organic group, the monovalent group having a polymerizable group is preferably a group represented by the following formula (5).

[ solution 5]

Y¹-R¹⁸-X²-* (5)

(in the formula (5), Y¹Is vinylphenyl, (meth) acryloyloxy, (meth) acryloylamino, vinyl, vinyloxy, or maleimido, R¹⁸Is a single bond, a divalent hydrocarbon group of 1 to 20 carbon atoms, X²Is a single bond, -CO-, a¹-O-CO-, or¹-NH-CO- (wherein, ") is¹"represents and R¹⁸A bond of (c); "+" represents a bond with the nitrogen atom in the formula (1) or the formula (2)

Among the monomers (R1) used in the synthesis of the addition polymer (A1), R is¹And R²When the ring structures X are bonded to each other to form a ring structure X, the ring structure X may be a monocyclic ring or a polycyclic ring (including a condensed ring and a bridged ring). The ring structure X is preferably a C4-15, more preferably a C4-12 ring structure.

Preferred specific examples of the ring structure X include: monocyclic structures represented by the following formulae (x1-1) to (x 1-4); and polycyclic structures represented by the following formulae (x2-1) to (x 2-8).

[ solution 6]

(wherein "+" represents a bond)

Specific examples of the monomer (R1) used for synthesizing the addition polymer (A1) include compounds represented by the following formulae (R1-1) to (R1-29) as represented by the formula (1); examples of the compound represented by the formula (2) include compounds (ring-opened compounds) obtained by ring-opening a succinimide ring or a glutarimide ring contained in the compounds represented by the following formulae (r1-1) to (r 1-29).

[ solution 7]

[ solution 8]

[ solution 9]

[ solution 10]

[ solution 11]

[ solution 12]

[ solution 13]

(in the formulae (R1-1) to (R1-29), R²⁰An alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms wherein at least one hydrogen atom is substituted with a fluorine atom or a cyano group, a substituted alkoxy group having 1 to 10 carbon atoms wherein at least one hydrogen atom is substituted with a fluorine atom or a cyano group, a fluorine atom, or a cyano group; r²¹Is a hydrogen atom or a methyl group; r²²An alkanediyl group having 1 to 10 carbon atoms)

The monomer (R1) can be synthesized according to conventional methods of organic chemistry. For example, the compound represented by the formula (2) can be obtained by synthesizing a compound represented by the following formula (R-1) using aminoalkanedioic acid (e.g., 2-aminobutyric acid, 2-aminoglutaric acid, etc.) as a raw material, and further reacting the compound represented by the following formula (R-1) with a compound represented by the following formula (R-2). In addition, the compound represented by the formula (1) can be obtained by ring closure of the compound represented by the formula (2) in the presence of a catalyst (for example, zinc chloride, a silylating agent, or the like) as necessary. The method for synthesizing the monomer (R1) is not limited to the above method.

[ solution 14]

(in the formulae (R-1) and (R-2), R¹、R²、A¹N1 and n2 are as defined in the above formulae (1) and (2)

From the viewpoint of improving the pretilt angle characteristics (initial pretilt angle and post-bake margin), the content of the structural unit U1 in the addition polymer (a1) is preferably 1 mol% or more, more preferably 2 mol% or more, and still more preferably 5 mol% or more, based on all monomer units of the addition polymer (a 1). The content of the structural unit U1 may be arbitrarily set within a range of 100 mol% or less with respect to all monomer units of the addition polymer (a 1). When a different structural unit from the structural unit U1 is introduced, the content of the structural unit U1 is preferably 90 mol% or less, more preferably 80 mol% or less, further preferably 60 mol% or less, and particularly preferably 50 mol% or less, based on all monomer units of the addition polymer (a 1). The addition polymer (a1) may have one or more than two kinds of the structural units U1.

(other structural units)

The addition polymer (a1) may have only the structural unit U1, or may have the structural unit U1 and a structural unit derived from a monomer different from the monomer (R1) (hereinafter, also referred to as "other structural unit"). The addition polymer (a1) preferably has, as another structural unit, a structural unit derived from at least one selected from the group consisting of a compound having a maleimide structure, a (meth) acrylic acid compound, a compound having a styrene structure, a compound having a maleic anhydride structure, and a cyclic olefin compound.

The compound having a maleimide structure is not particularly limited as long as it is a compound having a maleimide ring or an open ring thereof. Specific examples of the compound having a maleimide structure include a compound represented by the following formula (z-1) and a compound represented by the following formula (z-2).

[ solution 15]

(in the formulae (z-1) and (z-2), R³¹、R³²、R³⁴And R³⁵Each independently is a hydrogen atom or a methyl group; r³³And R³⁶Independently of one another are monovalent organic radicals

In the formulae (z-1) and (z-2), R is³³And R³⁶Examples of the monovalent organic group include: a C1-40 monovalent hydrocarbon group, at least one methylene group of the hydrocarbon group being substituted by-O-, -CO-, -COO-, -NR²⁶-or-CONR²⁶- (wherein, R)²⁶A hydrogen atom or a monovalent hydrocarbon group) (hereinafter also referred to as "group β"), a monovalent hydrocarbon group having 1 to 40 carbon atoms or a group β in which at least one hydrogen atom is substituted with a substituent such as a fluorine atom, a cyano group, a carboxyl group, an epoxy group, a hydroxyl group or a cyclic carbonate group. R³³And R³⁶The monovalent organic group(s) is preferably a group having a photo-alignment group, a group having a vertical-alignment group, or a group having a crosslinking group. At R³³And R³⁶When the monovalent organic group (2) is a group having a photo-alignment group, the group having a photo-alignment group preferably has a cinnamic acid structure represented by the formula (3).

Here, the "vertical alignment group" is a functional group that imparts a function of inducing a desired pretilt angle to a coating film formed using a liquid crystal aligning agent. The vertical alignment group exhibits a property of vertically aligning liquid crystal molecules independently of light irradiation. Specific examples of the vertical alignment group include: a C4-40 alkyl group, a C4-40 alkoxy group, a C4-40 fluoroalkyl group, a C4-40 fluoroalkoxy group, a C12-50 group having a structure in which two or more rings (preferably 1, 4-phenylene and 1, 4-cyclohexylene) are bonded via a single bond or a divalent linking group (-O-, -COO-, a C1-3 alkanediyl group, or the like), a C17-51 group having a steroid (steroid) skeleton, or the like.

Examples of the compound having a maleimide structure include: n-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4-carboxyphenylmaleimide, 2-methylphenylmaleimide, 4-hydroxyphenylmaleimide, N-dodecylmaleimide, N-cholestenoxycarbonylphenylmaleimide, and compounds (open rings) obtained by opening the maleimide ring of these compounds.

The (meth) acrylic compound may have a (meth) acryloyl group, and the remaining structure is not particularly limited. Specific examples of the (meth) acrylic compound include: (meth) acrylic acid, alpha-ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, alkyl (meth) acrylate, cycloalkyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl alpha-ethylacrylate, glycidyl alpha-n-propylacrylate, glycidyl alpha-n-butylacrylate, 3, 4-epoxybutyl (meth) acrylate, 3, 4-epoxybutyl (alpha-ethylacrylate), 3, 4-epoxycyclohexylmethyl (meth) acrylate, 6, 7-epoxyheptyl (alpha-ethylacrylate, 4-hydroxybutyl glycidyl ether acrylate, maleic acid, fumaric acid, itaconic acid, alkyl (meth) acrylate, cycloalkyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (alpha-ethylmethacrylate), glycidyl (alpha-n-butylacrylate), glycidyl (alpha-butylacrylate), 3, 4-epoxybutyl acrylate), 3, 4-epoxycyclohexylmethyl (meth) acrylate, 6, 7-epoxyheptyl (meth) acrylate, 6, 7-epoxyheptyl (meth) acrylate, 4-hydroxybutyl glycidyl ether, 2, or a mixture thereof, 3-ethyloxetan-3-yl (meth) acrylate, propylene carbonate (meth) acrylate, 3-hydroxy-1-adamantyl (meth) acrylate, and the like.

As the compound containing a styrene structure, there can be mentioned: styrene, methylstyrene, 4-vinyl-1-glycidyloxymethylbenzene, 3-vinylbenzoic acid, 4-vinylbenzoic acid, and the like. Examples of the compound having a maleic anhydride structure include: maleic anhydride, citraconic anhydride, and the like. As the cyclic olefin compound, there can be mentioned: cyclobutene, cyclopentyne, cyclohexene, bicyclo [2.2.1] hept-2-ene, and the like.

Examples of the other structural units of the addition polymer (a1) include, in addition to the above units: vinyl group-containing compounds such as ethylene, vinyl alcohol, (meth) allyl alcohol, and 3-methyl-3-buten-1-ol; conjugated diene compounds such as 1, 3-butadiene and 2-methyl-1, 3-butadiene. The addition polymer (a1) may have only one kind of other structural unit, or may have two or more kinds of other structural units.

A in structural element U1¹In the case of a monovalent group having a photo-alignment group, the addition polymer (a1) is preferably a structural unit having a structural unit U1 and a structural unit derived from a monomer having no photo-alignment group and at least one selected from the group consisting of a maleimide structure-containing compound, (meth) acrylic acid compound, a styrene structure-containing compound, a maleic anhydride structure-containing compound, and a cyclic olefin compound (hereinafter also referred to as "structural unit U2"), from the viewpoint of suppressing an excessive increase in pretilt angle exhibited by the liquid crystal alignment film.

In A¹In the case of a monovalent group having a photo-alignment group, the content of the structural unit U2 in the addition polymer (a1) is preferably 50 mol% or more, more preferably 55 mol% or more, and still more preferably 60 mol% or more, based on all monomer units of the addition polymer (a 1). The content of the structural unit U2 is preferably 99 mol% or less, more preferably 98 mol% or less, and still more preferably 95 mol% or less, based on all monomer units of the addition polymer (a 1). The addition polymer (a1) may have only one or two or more kinds of the structural unit U2.

(Cyclic ether Structure and Cyclic carbonate Structure)

In terms of further reducing the deviation of the pretilt angle (post-baking margin) with respect to the difference in the heating temperature (post-baking temperature) at the time of film formation, the addition polymer (a1) preferably has a structural unit derived from a monomer having at least one selected from the group consisting of a cyclic ether structure and a cyclic carbonate structure (hereinafter, also referred to as "structural unit U3"). Examples of the cyclic ether structure include: an oxetane ring structure, an oxirane ring structure, and the like. Examples of the cyclic carbonate structure include an ethylene carbonate structure and a propylene carbonate structure. Among these, the structural unit U3 is preferably a structural unit derived from a monomer having a cyclic ether structure, and more preferably a structural unit derived from a monomer having an oxetane ring structure or an oxirane ring structure.

The structural unit U3 is preferably a structural unit derived from at least one selected from the group consisting of a (meth) acrylic acid compound, a compound having a maleimide structure, and a compound having a styrene structure. Among these, a structural unit derived from at least one selected from the group consisting of a (meth) acrylic compound and a compound having a styrene structure is more preferable in terms of high degree of freedom in selection of monomers. Further, the structural unit U3 may constitute at least a part of the structural unit U2 included in the addition polymer (a 1).

When the addition polymer (a1) has the structural unit U3, the proportion of the structural unit U3 is preferably 2 mol% or more, more preferably 5 mol% or more, further preferably 10 mol% or more, and further preferably 20 mol% or more, based on all monomer units of the addition polymer (a 1). The content of the structural unit U3 is preferably 90 mol% or less, more preferably 85 mol% or less, and still more preferably 70 mol% or less, based on all monomer units of the addition polymer (a 1). The addition polymer (a1) may have only one or two or more kinds of the structural unit U3.

(reactive functional group)

From the viewpoint of further improving the effect of improving the post-baking margin, the addition polymer (a1) preferably has a functional group (hereinafter, also referred to as "reactive functional group") that reacts with at least one of the cyclic ether structure and the cyclic carbonate structure. Examples of reactive functional groups include: carboxyl group, hydroxyl group, isocyanate group, amino group, and groups in which these groups are protected with a protecting group. Among these, the reactive functional group is preferably at least one selected from the group consisting of a carboxyl group and a protected carboxyl group (hereinafter, also referred to as "protected carboxyl group") in view of good storage stability and high reactivity by heating.

The protected carboxyl group is not particularly limited as long as it is a protected carboxyl group which is released by heat to form a carboxyl group. Preferred specific examples of the protected carboxyl group include a structure represented by the following formula (6), an acetal ester structure of a carboxylic acid, a ketal ester structure of a carboxylic acid, and the like.

[ solution 16]

(in the formula (6), R⁴¹、R⁴²And R⁴³Satisfies the following (i) or (ii). (i) R⁴¹、R⁴²And R⁴³Each independently an alkyl group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. (ii) R⁴¹And R⁴²Represents R⁴¹And R⁴²Are bonded to each other to R⁴¹And R⁴²A divalent alicyclic hydrocarbon group or cyclic ether group having 4 to 20 carbon atoms, which is composed of the bonded carbon atoms. R⁴³Is alkyl group having 1 to 10 carbon atoms, alkenyl group having 2 to 10 carbon atoms or aryl group having 6 to 20 carbon atoms; "+" indicates a bond)

The monomer having a reactive functional group is preferably at least one selected from the group consisting of a (meth) acrylic compound, a compound having a maleimide structure, and a compound having a styrene structure. Among these, at least one selected from the group consisting of (meth) acrylic acid compounds and compounds containing a styrene structure is more preferable in terms of high degree of freedom in selection of monomers.

When the addition polymer (a1) has a structural unit derived from a monomer having a reactive functional group (hereinafter, also referred to as "structural unit U4"), the proportion of the structural unit U4 is preferably 2 mol% or more, more preferably 5 mol% or more, and still more preferably 10 mol% or more, based on all the monomer units of the addition polymer (a 1). The content of the structural unit U4 is preferably 70 mol% or less, more preferably 60 mol% or less, and still more preferably 50 mol% or less, based on all monomer units of the addition polymer (a 1). Further, the structural unit U4 may constitute at least a part of the structural unit U2 of the addition polymer (a 1). The structural unit U4 of the addition polymer (a1) may be one type, or two or more types.

(light intensifying Structure)

The polymer (a) may have a partial structure (hereinafter, also referred to as "photosensitized structure") capable of exhibiting a photosensitizing function that exhibits a photosensitizing effect by light irradiation. In the case where the polymer (a) has a photo-sensitizing structure, a liquid crystal alignment film having less variation in pretilt angle due to a difference in heating temperature at the time of film formation can be obtained, and this is preferable. Here, the "photosensitizing function" refers to a function of rapidly generating intersystem crossing (intersystem crossing) to transition to a triplet excited state after becoming a singlet excited state (single excited state) by irradiation with light. If the triplet state collides with another molecule, the opposite molecule is changed to an excited state and returns to its original state.

The photo-sensitizing structure of the polymer (a) is not particularly limited, and examples thereof include: acetophenone structure, benzophenone structure, anthraquinone structure, biphenyl structure, terphenyl structure, carbazole structure, nitroaryl structure (nitrobenzene structure, 1, 3-dinitrobenzene structure, etc.), naphthalene structure, fluorene structure, anthracene structure, 9, 10-dihydroanthracene structure, acridine structure, indole structure, 1, 4-dioxocyclohexa-2, 5-diene structure, etc. The polymer (a) preferably has a photosensitizing structure in a side chain.

When the addition polymer (a1) is a polymer having a photo-sensitizing structure, the method for obtaining the addition polymer (a1) is not particularly limited, and it is preferable to polymerize the monomer (R1) and the monomer having a photo-sensitizing structure. Specific examples of the monomer having a photosensitizing structure include compounds represented by the following formula (9).

Y²-L¹-Y³ …(9)

(in the formula (9), Y²Is a vinylphenyl group, (meth) acryloyloxy group, (meth) acryloylamino group, vinyl group, vinyloxy group, or maleimido group,L¹is a single bond or a divalent linking group, Y³Being bases with light-intensifying structures

In the formula (9), Y is Y in the sense that the degree of freedom in selection of the monomer can be increased²It is preferably a (meth) acryloyloxy group or a (meth) acryloylamino group, more preferably a (meth) acryloyloxy group. L is¹The divalent linking group(s) is preferably a divalent hydrocarbon group having 1 to 10 carbon atoms or a group having-O-between carbon-carbon bonds of the hydrocarbon group. Y is³Preferably an acetophenone structure, a benzophenone structure, an anthraquinone structure, a biphenyl structure, a terphenyl structure, a carbazole structure, a nitroaryl structure, a naphthalene structure, a fluorene structure, an anthracene structure, a 9, 10-dihydroanthracene structure, an acridine structure, an indole structure, or a1, 4-dioxocyclohex-2, 5-diene structure.

When the addition polymer (a1) has a structural unit derived from a monomer having a photosensitizing structure (hereinafter, also referred to as "structural unit U5"), the proportion of the structural unit U5 is preferably 1 mol% or more, more preferably 2 mol% or more, and still more preferably 3 mol% or more, based on all monomer units of the addition polymer (a 1). The content of the structural unit U5 is preferably 50 mol% or less, more preferably 40 mol% or less, and still more preferably 30 mol% or less, based on all monomer units of the addition polymer (a 1). Further, the structural unit U5 may constitute at least a part of the structural unit U2 included in the addition polymer (a 1). The structural unit U5 of the addition polymer (a1) may be one type, or two or more types.

The addition polymer (a1) can be obtained by: it is preferable to polymerize the monomer (R1) and other monomers used as needed in the presence of a polymerization initiator and in an organic solvent. Examples of the polymerization initiator to be used include: azo compounds such as 2,2' -azobis (isobutyronitrile), 2' -azobis (2, 4-dimethylvaleronitrile), and 2,2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile), and nickel catalysts. The use ratio of the polymerization initiator is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of all monomers used in the reaction. Examples of the organic solvent to be used include: alcohols, ethers, ketones, amides, esters, hydrocarbons, and the like.

In the polymerization reaction, 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 used is preferably such that the total amount (b) of the monomers used in the reaction is 0.1 to 60% by mass relative to the total amount (a + b) of the reaction solution. The reaction solution in which the polymer is dissolved can be prepared by separating the addition polymer (a1) contained in the reaction solution by a known separation method such as a method of drying precipitates obtained by injecting the reaction solution into a large amount of a poor solvent under reduced pressure, a method of distilling off the reaction solution under reduced pressure by an evaporator, and the like, and then subjecting the separated product to the preparation of a liquid crystal aligning agent.

The weight average molecular weight (Mw) of the addition polymer (a1) in terms of polystyrene as measured by Gel Permeation Chromatography (GPC) is preferably 1,000 to 300,000, more preferably 2,000 to 100,000. The molecular weight distribution (Mw/Mn) represented by the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC is preferably 7 or less, more preferably 5 or less. The addition polymer (a1) used for the preparation of the liquid crystal aligning agent may be one type, or two or more types may be combined.

(polycondensate)

The polycondensate (a2) is not particularly limited as long as it is a polymer obtained using a monomer having a group capable of undergoing polycondensation as a polymerizable group, and the main skeleton thereof is not particularly limited. The polycondensate (a2) is preferably a polyorganosiloxane having a structural unit U1 (hereinafter, also referred to as "polyorganosiloxane (a)") in terms of high improvement effects of coating uniformity and pretilt angle characteristics of the obtained liquid crystal alignment film. The polyorganosiloxane (a) can be obtained by a hydrolysis-condensation reaction using a hydrolyzable silane compound represented by the formula (1) or the formula (2) (hereinafter, also referred to as "specific silane compound") as the monomer (R1).

With respect to the specific silane compound, R in the formulas (1) and (2)¹And R²One of them is a monovalent group having a polymerizable group, and the other is a hydrogen atom or a monovalent groupAnd (4) a machine base. The polymerizable group is preferably an alkoxysilyl group. The specific silane compound is preferably at least one selected from the group consisting of a compound represented by the following formula (7) and a compound represented by the following formula (8).

[ solution 17]

(in the formulae (7) and (8), R²³Is a C1-20 divalent hydrocarbon group, R²⁴And R²⁵Each independently a C1-10 monovalent hydrocarbon group, R²⁷Is a hydrogen atom or a monovalent organic group; k is an integer of 1-3; a. the¹、A²N1 and n2 are as defined in the above formulae (1) and (2)

Specific examples of the specific silane compounds include compounds represented by the following formulae (s1-1) to (s 1-10).

[ solution 18]

[ solution 19]

(in the formulae (s1-1) to (s1-10), R²³、R²⁴、R²⁵And k is the same as the formula (7); r²⁰An alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms wherein at least one hydrogen atom is substituted with a fluorine atom or a cyano group, a substituted alkoxy group having 1 to 10 carbon atoms wherein at least one hydrogen atom is substituted with a fluorine atom or a cyano group, a fluorine atom, or a cyano group)

In the synthesis of the polyorganosiloxane (a), as the hydrolyzable silane compound, only the specific silane compound may be used, or a hydrolyzable silane compound other than the specific silane compound (hereinafter, also referred to as "other silane compound") may be used in combination.

The other silane compound is not particularly limited as long as it can be polycondensed with a specific silane compound, and examples thereof include: tetraalkoxysilane compounds or alkylalkoxysilane compounds such as tetramethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane; cycloalkylalkoxysilane compounds such as cyclohexyltrimethoxysilane and cyclohexylmethyldimethoxysilane; arylalkoxysilane compounds such as phenyltrimethoxysilane and phenyltriethoxysilane; nitrogen-sulfur-containing alkoxysilane compounds such as 3-mercaptopropyltriethoxysilane, mercaptomethyltriethoxysilane, 3-aminopropyltrimethoxysilane and N- (3-cyclohexylamino) propyltrimethoxysilane; epoxy group-containing silane compounds such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane; unsaturated bond-containing alkoxysilane compounds such as 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane, 3- (meth) acryloyloxypropylmethyldiethoxysilane, vinyltriethoxysilane, and p-styryltrimethoxysilane; silane compounds containing an anhydride group such as trimethoxysilylpropyl succinic anhydride; isocyanate group-containing silane compounds such as 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane, and the like. As the other silane compound, one of these may be used alone or two or more of these may be used in combination. Further, "(meth) acryloyl" means "acryloyl" and "methacryloyl".

From the viewpoint of improving the pretilt angle characteristics (initial pretilt angle and post-baking margin), the content ratio of the structural unit U1 in the polyorganosiloxane (a) is preferably 1 mol% or more, more preferably 2 mol% or more, and still more preferably 5 mol% or more, based on all monomer units of the polyorganosiloxane (a). The content of the structural unit U1 is preferably 90 mol% or less, more preferably 80 mol% or less, and still more preferably 60 mol% or less, based on all monomer units of the polyorganosiloxane (a). The polyorganosiloxane (a) may have one or more of the structural units U1.

The hydrolysis-condensation reaction is carried out by: it is preferable that one or more of the hydrolyzable silane compounds described above are reacted with water in the presence of an appropriate catalyst and an organic solvent. During the reaction, the proportion of water used is preferably 1 to 30 moles per 1 mole of the silane compound (total amount). Examples of the catalyst to be used include: acids, alkali metal compounds, organic bases, titanium compounds, zirconium compounds, and the like. The amount of the catalyst to be used varies depending on the kind of the catalyst, reaction conditions such as temperature, and the like, and is suitably set, for example, preferably from 0.01 to 3 times by mol based on the total amount of the silane compounds. Examples of the organic solvent used include hydrocarbons, ketones, esters, ethers, alcohols, and the like, and among these, it is preferable to use an organic solvent which is not water-soluble or hardly water-soluble. The use ratio of the organic solvent is preferably 10 to 10,000 parts by mass with respect to 100 parts by mass of the total of the silane compounds used in the reaction.

The hydrolysis-condensation reaction is preferably carried out by heating with an oil bath or the like, for example. In this case, the heating temperature is preferably 130 ℃ or lower, and the heating time is preferably 0.5 to 12 hours. After the reaction is completed, the organic solvent layer separated from the reaction solution is dried with a drying agent as necessary, and then the solvent is removed to obtain the target polyorganosiloxane. The method for synthesizing the polyorganosiloxane is not limited to the hydrolysis-condensation reaction, and may be carried out, for example, by the following method: a hydrolyzable silane compound is reacted in the presence of oxalic acid and an alcohol.

The polyorganosiloxane (A) preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by GPC in the range of 100 to 50,000, more preferably in the range of 200 to 10,000.

In the liquid crystal aligning agent of the present disclosure, the content ratio of the polymer (a) to all polymers contained in the liquid crystal aligning agent is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, from the viewpoint of sufficiently improving coatability to a substrate and making pretilt angle characteristics (initial pretilt angle, post-bake margin) excellent. The content of the polymer (a) may be appropriately set within a range of 100% by mass or less with respect to all the polymers contained in the liquid crystal aligning agent. According to the polymer (A), even if the amount of the polymer (A) used is reduced, the effects of improving the coating uniformity and pretilt angle characteristics can be obtained. From the viewpoint of achieving cost reduction of the liquid crystal aligning agent and sufficiently achieving improvement in reliability, the content ratio of the polymer (a) is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less, relative to the total amount of the polymers contained in the liquid crystal aligning agent.

< other ingredients >

The liquid crystal aligning agent of the present disclosure may also contain other components than the polymer (a) as necessary.

(other Polymer)

In the liquid crystal aligning agent of the present disclosure, the polymer (a) and a polymer having no structural unit derived from the monomer (R1) (hereinafter, also referred to as "other polymer") may be contained as polymer components. The other polymer is not particularly limited, and at least one polymer (hereinafter, also referred to as "polymer (B)") selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and polyurea can be preferably used. The use of the polymer (B) in combination with the polymer (a) is preferable in terms of ensuring the liquid crystal alignment properties and the electrical characteristics of the liquid crystal element to be obtained. The polymer (B) is more preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide.

In the case where the polymer (B) is a polyamic acid, the polyamic acid can be obtained by: a tetracarboxylic dianhydride is reacted with a diamine compound. In this case, as the tetracarboxylic dianhydride and the diamine compound, conventionally known compounds used for synthesis of polyamic acid can be used. The polyamic acid ester can be obtained, for example, by the following method or the like: a method of reacting the obtained polyamic acid with an esterifying agent (for example, methanol or ethanol, N-dimethylformamide diethylacetal, or the like); a method of reacting a tetracarboxylic acid diester with a diamine compound in the presence of a suitable dehydration catalyst; a process for reacting a tetracarboxylic acid diester dihalide with a diamine in the presence of a suitable base. The polyimide can be obtained, for example, by: the obtained polyamic acid is subjected to dehydration ring closure and imidization. The imidization ratio of the polyimide is preferably 20% to 90%, more preferably 30% to 80%.

The polymer (B) preferably has a weight average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 300,000, in terms of polystyrene as measured by GPC. The molecular weight distribution (Mw/Mn) is preferably 7 or less, more preferably 5 or less.

When the liquid crystal aligning agent contains the polymer (a) and the polymer (B) as polymer components, the content ratio of the polymer (B) is preferably 100 parts by mass or more with respect to 100 parts by mass of the polymer (a) in the liquid crystal aligning agent, from the viewpoint of sufficiently obtaining the effect of improving the pretilt angle characteristic by blending the polymer (a) and of improving the liquid crystal alignment property. The content ratio of the polymer (B) is more preferably 100 to 2000 parts by mass, and still more preferably 200 to 1500 parts by mass. The polymer (B) may be used alone or in combination of two or more.

(photosensitizing agent)

The liquid crystal aligning agent of the present disclosure preferably contains a compound having a photosensitizing structure (hereinafter, also referred to as "photosensitizing agent"). The photosensitizer may be the polymer (a) having a structural unit derived from the monomer (R1) and a photosensitizing structure, may be another polymer, or may be an additive component (hereinafter, also referred to as "additive (S)") separately prepared independently from the polymer component. The liquid crystal aligning agent may contain both the polymer (a) and the additive (S). The additive (S) is preferably a compound having a photosensitizing structure and a molecular weight of 1000 or less.

Specific examples of the additive (S) include: acetophenone-structure-containing compounds such as acetophenone, acetophenone benzyl ketal, 2-dimethoxy-2-phenylacetophenone, 3-methylacetophenone, etc.; benzophenone structure-containing compounds such as benzophenone, 4-diethylamino-2-hydroxybenzophenone, 4-methylbenzophenone, 3- (4-benzoyl-phenoxy) propyl, 4 '-dimethoxybenzophenone, 4' -diaminobenzophenone, 4 '-bis (dimethylamino) benzophenone (Michler's ketone), and the like; nitroaryl structure-containing compounds such as 3, 5-dinitrobenzene, 4-methyl-3, 5-dinitrobenzene, 3- (3, 5-dinitrophenoxy) propyl, and 2-methyl-3, 5-dinitrobenzene; hydrocarbons such as naphthalene, anthracene, biphenyl, terphenyl, 2, 3-benzofluorene, pyrene, perylene, fluorene, anthraquinone, and the like; anthracene derivatives such as 9, 10-dioxo-9, 10-dihydroanthracene, 3- (9, 10-dioxo-9, 10-dihydroanthracene-2-yl) propyl, 2-oxo-9, 10-dihydroanthracene, etc.; amino group-containing compounds such as triphenylamine and carbazole; sulfur-containing compounds such as thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothianthrone and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinyl-propan-1-one; phosphorus-containing compounds such as 2,4, 6-trimethylbenzoyldiphenylphosphine oxide and bis- (2, 6-dimethoxybenzoyl) -2,4, 4-trimethylpentylphosphine oxide. Further, as the additive (S), one kind may be used alone, or two or more kinds may be used in combination.

In the case where the additive (S) is used as the photosensitizer, the content ratio of the additive (S) in the liquid crystal aligning agent is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, with respect to 100 parts by mass of the total amount of the polymer components in the liquid crystal aligning agent, from the viewpoint of further improving the effect of reducing the post-baking margin. From the viewpoint of suppressing the performance degradation caused by excessive addition, the content of the additive (S) is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, relative to 100 parts by mass of the total amount of the polymer components.

(solvent)

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

As the solvent component of the liquid crystal aligning agent, a solvent (hereinafter, also referred to as "specific solvent") having a boiling point of 180 ℃ or lower at 1 atm, which is at least one selected from the group consisting of the compound represented by the following formula (D-1), the compound represented by the following formula (D-2), and the compound represented by the following formula (D-3), can be preferably used. By using a specific solvent as at least a part of the solvent component, a liquid crystal element excellent in liquid crystal alignment properties and electric characteristics can be obtained even when heating is performed at low temperature (for example, 200 ℃ or lower) during film formation, which is preferable in view of the above.

[ solution 20]

(in the formula (D-1), R¹Is C1-4 alkyl or CH₃CO-，R²Is C1-C4 alkanediyl or- (CH)₂CH₂O)n-CH₂CH₂- (wherein n is an integer of 1 to 4), R³Is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms)

[ solution 21]

(in the formula (D-2), R⁴An alkanediyl group having 1 to 3 carbon atoms)

[ solution 22]

(in the formula (D-3), R⁵And R⁶Each independently an alkyl group having 4 to 8 carbon atoms)

Specific examples of the specific solvent include compounds represented by the formula (D-1): propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol methyl ethyl ether, 3-methoxy-1-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.;

as the compound represented by the formula (D-2), there can be mentioned: cyclobutanone, cyclopentanone, cyclohexanone;

examples of the compound represented by the formula (D-3) include diisobutyl ketone and the like. One kind of the specific solvent may be used alone, or two or more kinds may be used in combination.

The solvent component of the liquid crystal aligning agent may contain only the specific solvent, or may be a mixed solvent of a solvent other than the specific solvent and the specific solvent. Examples of other solvents include: high-polarity solvents such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1, 2-dimethyl-2-imidazolidinone, γ -butyrolactone, γ -butyrolactam, N-dimethylformamide, N-dimethylacetamide, and the like; in addition to these, there may be mentioned:

4-hydroxy-4-methyl-2-pentanone, butyl lactate, butyl acetate, methyl methoxy propionate, ethyl ethoxy propionate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, ethylene carbonate, propylene carbonate, cyclohexane, octanol, tetrahydrofuran, and the like. These may be used singly or in combination of two or more.

The content ratio of the specific solvent in the solvent component contained in the liquid crystal aligning agent is preferably 20 mass% or more, more preferably 40 mass% or more, and still more preferably 50 mass% or more, relative to the total amount of the solvent contained in the liquid crystal aligning agent.

Examples of the other components contained in the liquid crystal aligning agent include, in addition to the above components: a functional silane compound, a polyfunctional (meth) acrylate, an antioxidant, a metal chelate compound, a hardening accelerator, a surfactant, a filler, a dispersant, a photosensitizer, and the like. The blending ratio of the other components may be appropriately selected depending on each compound within a range not impairing the effect of the present disclosure.

The concentration of the solid component in the liquid crystal aligning agent (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) may 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 1 mass% or more, a coating film having a sufficient film thickness can be obtained, and a good liquid crystal alignment film can be easily obtained. On the other hand, when the solid content concentration is 10 mass% or less, the film thickness of the coating film is not excessively large, and the viscosity of the liquid crystal aligning agent can be made appropriate, and the decrease in coatability can be suppressed, which is preferable in view of the above.

Liquid crystal alignment film and liquid crystal element

The liquid crystal alignment film of the present disclosure is formed of the liquid crystal aligning agent prepared as described. In addition, the liquid crystal element of the present disclosure includes a liquid crystal alignment film formed using the liquid crystal aligning agent described above. The operation mode of the liquid crystal In the liquid crystal element is not particularly limited, and can be applied to various modes such as a Twisted Nematic (TN) mode, a Super Twisted Nematic (STN) mode, a Vertical Alignment (VA) mode (including a Vertical Alignment-Multi-domain Vertical Alignment (VA-MVA) mode, a Vertical Alignment-Patterned Vertical Alignment (VA-PVA) mode, etc.), an In-Plane Switching (IPS) mode, an Fringe Field Switching (FFS) mode, an Optically Compensated Bend (Optically Compensated Bend, OCB) mode, a Polymer Stabilized Alignment (PSA) mode, and the like. The liquid crystal element can be manufactured by a method including, for example, the following steps 1 to 3. In step 1, the substrate used differs depending on the desired operation mode. Step 2 and step 3 are common to the respective operation modes.

< step 1: formation of coating film

First, a liquid crystal aligning agent is applied to a substrate, and preferably, the applied surface is heated, thereby forming a liquid crystal alignment layerA coating film is formed on a substrate. As the substrate, for example, a transparent substrate including the following materials can be used: float glass, soda glass, and the like; plastics such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (alicyclic olefin). As the transparent conductive film provided on one surface of the substrate, there can be used: containing tin oxide (SnO)₂) A film of (Nesa) (registered trademark of PPG Corp., USA) containing indium oxide-tin oxide (In)₂O₃-SnO₂) Indium Tin Oxide (ITO) film, and the like. In the case of manufacturing a TN-type, STN-type, or VA-type liquid crystal cell, 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 element, a substrate provided with electrodes patterned into a comb-tooth shape and an opposing substrate provided with no electrodes are used. The application of the liquid crystal aligning agent to the substrate is preferably performed by an offset printing method, a flexographic printing method, a spin coating method, a roll coater method or an inkjet printing method on the electrode-formed surface.

After the liquid crystal aligning agent is applied, it is preferable to perform preliminary heating (pre-baking) for the purpose of preventing dripping of the applied liquid crystal aligning 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 or the like. The calcination temperature (post-baking temperature) in this case is preferably 80 to 250 ℃, more preferably 80 to 200 ℃. The post-baking time is preferably 5 minutes to 200 minutes. In particular, when the prepared liquid crystal aligning agent is used, the solubility in a low boiling point solvent such as a specific solvent is good, and even when the post-baking temperature is set to, for example, 200 ℃ or less, preferably 180 ℃ or less, and more preferably 160 ℃ or less, the variation in pretilt angle due to the difference in the pre-baking temperature can be further reduced, which is preferable in view of the above. The film thickness of the film thus formed is preferably 0.001 to 1 μm.

< step 2: orientation treatment

In the case of producing a TN-type, STN-type, IPS-type, or FFS-type liquid crystal cell, a treatment (alignment treatment) is performed to impart liquid crystal alignment ability to the coating film formed in the above-described step 1. Thereby, the coating film is provided with the alignment ability of the liquid crystal molecules, and becomes a liquid crystal alignment film. In the case of producing a vertical alignment type liquid crystal cell, the coating film formed in the step 1 may be used as it is as a liquid crystal alignment film, but an alignment treatment may be applied to the coating film in order to further improve the liquid crystal alignment ability. As the alignment treatment, it is preferable to use 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.

Light irradiation for photo-alignment can 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 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, the ultraviolet light contains light having a wavelength of 200nm to 400 nm. When the radiation is polarized light, the radiation may be linearly polarized light or partially polarized light. When 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 an oblique direction.

Examples of the light source to be used include: low pressure mercury lamps, high pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, excimer lasers, and the like. The irradiation dose of the radiation is preferably 400J/m²～50,000J/m²More preferably 1,000J/m²～20,000J/m². After the light irradiation for imparting alignment ability, the substrate surface may be cleaned 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 thereof, or the substrate may be heated.

< step 3: construction of liquid Crystal cell

Two substrates on which liquid crystal alignment films are formed are prepared, and liquid crystal is disposed between the two substrates disposed to face each other, thereby manufacturing a liquid crystal cell. In the production of a liquid crystal cell, for example, the following methods can be mentioned: a method of arranging two substrates so that liquid crystal alignment films face each other with a gap therebetween, bonding peripheral portions of the two substrates with a sealant, filling a cell gap surrounded by the substrate surfaces and the sealant with a liquid crystal, and sealing the filling hole, and a method of using an One Drop Fill (ODF) method. As the sealant, for example, an epoxy resin containing a curing agent and alumina balls as spacers can be used. The liquid crystal includes nematic liquid crystal and smectic liquid crystal, and among them, nematic liquid crystal is preferable. In the PSA mode, after a liquid crystal cell is constructed, a light irradiation treatment is performed on the liquid crystal cell in a state where a voltage is applied between conductive films provided on a pair of substrates.

Then, a polarizing plate is bonded to the outer surface of the liquid crystal cell as necessary to produce a liquid crystal cell. Examples of the polarizing plate include: a polarizing plate in which a polarizing film called "H film" formed by absorbing iodine while stretching and orienting polyvinyl alcohol is sandwiched between cellulose acetate protective films, or a polarizing plate including the H film itself.

The liquid crystal element of the present disclosure can be effectively applied to various applications, for example, to various display devices such as a timepiece, a portable game machine, a word processor, a notebook Personal computer, a car navigation system, a camcorder, a Personal Digital Assistant (PDA), a Digital camera, a mobile phone, a smartphone, various monitors, a liquid crystal television, an information display, a light adjusting film, a retardation film, and the like.

Examples

The present disclosure will be described more specifically with reference to the following examples, but the present disclosure is not limited to these examples.

In the following examples and comparative examples, the weight average molecular weight and the number average molecular weight of the polymer were measured by the following methods.

[ weight average molecular weight (Mw) and number average molecular weight (Mn) of Polymer ]

The weight average molecular weight and the number average molecular weight were polystyrene conversion values measured by gel permeation chromatography under the following conditions.

Pipe column: TSKgelGRCXLII manufactured by Tosoh corporation

Solvent: tetrahydrofuran (THF)

Temperature: 40 deg.C

Pressure: 68kgf/cm²

The structural formula of the compound used in this example is shown below. Hereinafter, the compound represented by the formula (X) may be simply referred to as the compound (X) for convenience.

[ solution 23]

[ solution 24]

[ solution 25]

[ solution 26]

< Synthesis of Compound >

Synthetic examples 1 to 1: synthesis of Compound (MA-2)

Compound (MA-2) was synthesized according to the following scheme.

[ solution 27]

13.3g of aspartic acid and 200ml of Tetrahydrofuran (THF) were put into an eggplant-shaped flask and dissolved therein. To this solution, 9.81g of maleic acid was added, and after stirring for 1 hour, the solvent was distilled off by an evaporator. To the solid thus obtained were added 300ml of toluene, 24.2g of hexamethyldisilazane and 27.3g of zinc chloride, and the mixture was reacted at 80 ℃ for 4 hours. After the reaction, the reaction solution was subjected to twice liquid separation purification with hydrochloric acid (1N) and twice liquid separation purification with water. Then, the organic layer was concentrated by an evaporator. The obtained solid was crystallized from THF/ethanol/water, whereby 14.2g of intermediate 1 was obtained.

Intermediate 1 was dissolved in THF, 28.6g of cinnamamide represented by the above formula (CA) (hereinafter, referred to as "compound CA") was added thereto, and the mixture was reacted at 50 ℃ for 1 hour. After the reaction, the solvent was distilled off, whereby 42.5g of compound (MA-2) was obtained.

Synthetic examples 1 to 2: synthesis of Compound (MA-1)

Compound (MA-1) was synthesized according to the following scheme.

[ solution 28]

To 17.9g of the compound (MA-2), 300ml of toluene, 7.26g of hexamethyldisilazane and 8.18g of zinc chloride were added, and the mixture was reacted at 80 ℃ for 4 hours. After the reaction, the reaction solution was subjected to twice liquid separation purification with hydrochloric acid (1N) and twice liquid separation purification with water. Then, the organic layer was concentrated by an evaporator. The obtained solid was crystallized from THF/ethanol/water, whereby 7.34g of the compound (MA-1) was obtained.

Synthetic examples 1 to 3: synthesis of Compound (MA-3)

Synthesis was carried out in the same manner as for the compound (MA-2) except that 3-aminoglutaric acid was used as the starting material.

Synthetic examples 1 to 4: synthesis of Compound (MA-4)

Compound (MA-4) was synthesized according to the following scheme.

[ solution 29]

200ml of dehydrated THF was added to 13.3g of aspartic acid in a three-necked eggplant-shaped flask and dissolved therein while passing nitrogen gas therethrough. 15.5g of "Karenz MOI" (manufactured by Showa Denko K.K.) was added thereto, and the mixture was reacted at 50 ℃ for 8 hours, and the solvent was distilled off. Then, 300ml of toluene, 24.2g of hexamethyldisilazane, 27.3g of zinc chloride, and 1g of dibutylhydroxytoluene were added thereto, and the mixture was reacted at 50 ℃ for 8 hours. After the reaction, the reaction solution was subjected to twice liquid separation purification with hydrochloric acid (1N) and twice liquid separation purification with water. Then, the organic layer was concentrated by an evaporator. The obtained solid was crystallized from THF/ethanol/water, thereby obtaining 10.0g of intermediate 2.

Then, intermediate 2 was dissolved in THF, 14.5g of compound CA was added thereto, and the mixture was reacted at 50 ℃ for 1 hour. After the reaction, the solvent was distilled off, whereby 22.9g of compound (MA-4) was obtained.

Synthetic examples 1 to 5: synthesis of Compound (MA-5)

The synthesis was carried out in the same manner as in the case of the compound (MA-4) except that the starting material was 5-norbornene-2, 3-dicarboxylic anhydride.

Synthetic examples 1 to 6: synthesis of Compound (MA-6)

Compound (MA-6) was synthesized according to the following scheme.

[ solution 30]

13.3g of aspartic acid, 10ml of pyridine and 150ml of dehydrated THF were put into an eggplant-shaped flask, and dissolved and cooled in an ice bath. 4-vinylbenzoic acid chloride dissolved in 50ml of dehydrated THF was slowly dropped thereinto, followed by allowing to react for 15 hours. After the reaction, 100ml of ethyl acetate was added, and liquid separation purification was performed twice using hydrochloric acid (1N) and liquid separation purification was performed twice using water. Then, the organic layer was concentrated by an evaporator. The obtained solid was subjected to crystallization using THF/ethanol/water, whereby 20.3g of intermediate 3 was obtained.

Intermediate 3 was dissolved in THF, and 32.4g of compound CA was added thereto, followed by reaction at 50 ℃ for 1 hour. After the reaction, the solvent was distilled off, whereby 51.6g of compound (MA-6) was obtained.

Synthetic examples 1 to 7: synthesis of Compound (MA-7)

Compound (MA-7) was synthesized according to the following scheme.

[ solution 31]

30ml of toluene, 4.84g of hexamethyldisilazane and 5.45g of zinc chloride were added to 3.46g of N-allylaspartic acid, and the mixture was reacted at 80 ℃ for 4 hours. After the reaction, the reaction solution was subjected to twice liquid separation purification with hydrochloric acid (1N) and twice liquid separation purification with water. Then, the organic layer was concentrated by an evaporator. The obtained solid was crystallized from THF/ethanol/water, whereby 1.68g of intermediate 4 was obtained.

The obtained intermediate 4 was dissolved in THF, and 4.27g of compound CA was added thereto, followed by reaction at 50 ℃ for 1 hour. After the reaction, the solvent was distilled off, thereby obtaining 5.45g of intermediate 5.

Further, 300. mu.l of intermediate 5 and 0.01M hexachloroplatinic (IV) acid hexahydrate solution were dissolved in THF20ml under a nitrogen atmosphere. 1.26g of trimethoxysilane was slowly added dropwise thereto, and thereafter, it was reacted at 70 ℃ for 3 days. After the reaction, the solvent was distilled off, and crystallization was performed using THF/ethanol, whereby 3.71g of compound (MA-7) was obtained.

< Synthesis of Polymer >

[ Synthesis examples 2-1]

In a 100mL two-necked flask, 1.71g (3.00mmol) of the compound (MA-1) as a polymerization monomer, 0.70g (7.00mmol) of the compound (MB-4), 0.10g (0.41mmol) of 2,2' -azobis (2, 4-dimethylpentanenitrile) as a radical polymerization initiator, 0.10g (0.44mmol) of 2, 4-diphenyl-4-methyl-1-pentene as a chain transfer agent, and 15mL of N-methyl-2-pyrrolidone (NMP) as a solvent were charged under nitrogen, and polymerization was carried out at 70 ℃ for 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried under vacuum at room temperature for 8 hours, thereby obtaining the objective polymer (P-1). The weight average molecular weight Mw, as measured in terms of polystyrene based on GPC, was 30000 and the molecular weight distribution Mw/Mn was 2.8.

Synthesis examples 2-2 to 2-5, 2-7 and 2-8

Polymers (P-2) to (P-5), (P-7) and (P-8) were synthesized in the same manner as in Synthesis example 2-1 except that the kinds and amounts of monomers used were changed as described in Table 1 below. In Table 1, the numerical units of the monomer compositions are "parts by mole".

[ Table 1]

Synthesis examples 2 to 6

A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser was charged with 40 parts by mole of compound (MA-7), 20 parts by mole of compound (MS-1) and 40 parts by mole of compound (MS-2) per 100 parts by mole of the total amount of monomers, and further charged with 50g of methyl isobutyl ketone and 5g of triethylamine, and mixed at room temperature. Then, 35g of deionized water was added dropwise over 30 minutes using a dropping funnel, and then mixed under reflux while allowing to react at 80 ℃ for 6 hours. After the reaction was completed, the organic layer was taken out, washed with a 0.2 mass% ammonium nitrate aqueous solution until the water after washing became neutral, and then the solvent and water were distilled off under reduced pressure, whereby a polymer (P-6) which was a polyorganosiloxane was obtained as a viscous transparent liquid. The weight-average molecular weight (Mw) of the obtained polymer (P-6) was 11000.

Synthesis examples 2 to 9

100 parts by mole of 1,2,3, 4-cyclobutanetetracarboxylic dianhydride and 100 parts by mole of 2,2 '-dimethyl-4, 4' -diaminobiphenyl were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 40 ℃ for 3 hours to obtain a solution containing 10 mass% of a polymer (P-9) which is a polyamic acid.

Synthesis examples 2 to 10

100 parts by mole of 2,3, 5-tricarboxycyclopentylacetic dianhydride, 20 parts by mole of 3, 5-diaminobenzoic acid, and 80 parts by mole of 2,2 '-dimethyl-4, 4' -diaminobiphenyl were dissolved in NMP and reacted at 40 ℃ for 3 hours, thereby obtaining a solution containing 10 mass% of polymer (P-10) as a polyamic acid.

Synthesis examples 2 to 11

A maleimide resin having a chalcone side chain (referred to as "polymer (P-11)") was synthesized in accordance with the procedure of production example 2 described in Korean laid-open patent publication No. 2015-138548.

Synthesis examples 2 to 12

A maleimide resin having a cinnamoyl group in its side chain (referred to as "Polymer (P-12)") was synthesized in accordance with the procedure of example 1 described in Japanese patent No. 2962473.

Synthesis examples 2 to 13

A styrene resin having a cinnamoyl group in the side chain (referred to as "polymer (P-13)") was synthesized in accordance with the procedure of production example 1 described in Japanese patent laid-open publication No. 2015-152743.

Synthesis examples 2 to 14

Polyamic acid was synthesized (as "Polymer (P-14)") by using 1,2,3, 4-cyclobutanetetracarboxylic dianhydride and acrylic acid (E) -3, 5-diaminobenzyl 3- (2- (4-butoxyphenyl) -1, 3-dioxoisoindolin-5-yl) ester in the order of example 27 described in Japanese patent application No. 5803915.

< production and evaluation of liquid Crystal display device >

[ example 1]

(1) Preparation of liquid crystal aligning agent

Cyclopentanone (CPN) and Butyl Cellosolve (BC) were added as solvents to a container containing 100 parts by mass of the polymer (P-1) obtained in synthesis example 2-1, to prepare a solution having a solvent composition of CPN/BC 70/30 (mass ratio) and a solid content concentration of 3.5 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 optical vertical liquid crystal display element

The liquid crystal aligning agent (AL-1) prepared in (1) was applied to the transparent electrode surface of a glass substrate with a transparent electrode, which included an ITO film, by a spinner, and prebaked for 1 minute by a hot plate at 80 ℃ to form a coating film having a thickness of 0.08. mu.m. Then, the surface of the coating film was irradiated with polarized ultraviolet light 200J/m containing 313nm bright lines at room temperature from a direction inclined at 40 ℃ from the substrate normal using an Hg-Xe lamp and a Glan-Taylor prism (Glan-Taylor prism)². Subsequently, the resultant was heated at 160 ℃ for 40 minutes in an oven in which the inside of the cell was replaced with nitrogen (main baking) to prepare a liquid crystal alignment film. The same operation was repeated to produce a pair (two) of substrates on which liquid crystal alignment films were formed.

An epoxy resin adhesive containing alumina balls having a diameter of 3.5 μm was applied to the outer periphery of the surface having the liquid crystal alignment film of one of the two substrates on which the liquid crystal alignment films were formed by screen printing, the liquid crystal alignment films of the pair of substrates were then placed in face-to-face relation, the pair of substrates were pressed together so that the projection directions of the optical axes of ultraviolet rays irradiated to the respective substrates on the substrate surfaces were antiparallel to each other, and the adhesive was thermally cured at 150 ℃ for 1 hour. Then, a gap between the substrates was filled with nematic liquid crystal (MLC-6608, manufactured by Merck) from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive to obtain a liquid crystal cell. Further, in order to remove the flow alignment at the time of liquid crystal injection, the liquid crystal cell was heated at 150 ℃ and then slowly cooled to room temperature. Then, polarizing plates are bonded to both outer surfaces of the substrate in the liquid crystal cell so that the polarization directions of the polarizing plates are orthogonal to each other and that an angle of 45 ° is formed with respect to the projection direction of the optical axis of the ultraviolet ray irradiated when the liquid crystal alignment film is formed on the substrate surface.

(3) Evaluation of pretilt Angle

With respect to the liquid crystal display element manufactured in the above (2), a value of an inclination angle of liquid crystal molecules with respect to a substrate surface is measured by a crystal rotation method using He — Ne laser light according to a method described in non-patent literature (t.j. scheffer et al.) "application physical journal (j.appl.phys.), (volume 19, page 2013) (1980)), and the value is set as a pretilt angle. In this case, "good" (o) "is set when the pretilt angle is less than 89.0 °, and" poor "(x)" is set when the pretilt angle is equal to or greater than 89.0 °. As a result, in the example, the pretilt angle was evaluated as "good (o)".

(4) Evaluation of coating uniformity

The liquid crystal aligning agent (AL-1) prepared in (1) was applied onto a glass substrate using a spinner, prebaked with a hot plate at 80 ℃ for 1 minute, and then heated in an oven at 200 ℃ with a nitrogen gas inside the chamber (postbaking) for 1 hour, thereby forming a coating film having an average film thickness of 0.1. mu.m. The surface of the obtained coating film was observed by an Atomic Force Microscope (AFM), and the center average roughness (Ra) was measured, thereby evaluating the uniformity of the coating film surface. The coating uniformity was evaluated as "good (. largecircle)" when Ra was 5nm or less, as "fair (. DELTA.) when Ra was more than 5nm and less than 10nm, and as" poor (. largecircle) "when Ra was 10nm or more. As a result, the evaluation of "ok (Δ)" in the example was described.

(5) Evaluation of Pre-Tilt Angle deviation characteristics (post-baking margin) with respect to differences in post-baking temperature

According to the method (2), liquid crystal alignment films were prepared at different post-baking temperatures (150 ℃ C. and 200 ℃ C.), and the pretilt angles of the two liquid crystal display elements obtained were measured, respectively. The variation characteristics of the pretilt angle with respect to the difference in the post-baking temperature were evaluated by the difference Δ θ (═ θ 200- θ 150|) between the measured value θ 200 of the pretilt angle of the liquid crystal display element with the post-baking temperature set at 200 ℃ and the measured value θ 150 of the pretilt angle of the liquid crystal display element with the post-baking temperature set at 150 ℃. It can be said that the smaller Δ θ, the better the deviation of the pretilt angle with respect to the difference in the pre-baking temperature is. The measurement of the pretilt angle was carried out by the method described in the above section "(3) evaluation of pretilt angle". In the evaluation, a case where Δ θ is 0.1 ° or less is "excellent" (. circleincircle), "a case where Δ θ is greater than 0.1 ° and 0.2 ° or less is" good "(. circleircle)," a case where Δ θ is greater than 0.2 ° and less than 0.5 ° is "acceptable" (. DELTA.), and a case where Δ θ is 0.5 ° or more is "poor" (. times.). As a result, the evaluation of "ok (Δ)" in the example was described.

Examples 2 to 10 and comparative examples 1 to 4

Liquid crystal aligning agents were prepared in the same manner as in example 1 except that the formulation of the liquid crystal aligning agent was changed as shown in table 2 below. Using the prepared liquid crystal aligning agents, an optical homeotropic liquid crystal display element was produced in the same manner as in example 1, and various evaluations were performed in the same manner as in example 1. The results are shown in table 2 below. In examples 3 to 10 and comparative examples 1 to 4, two kinds of polymers were blended. In example 10, an additive (photosensitizer) was added to the liquid crystal aligning agent.

[ Table 2]

In Table 2, the parenthesized values in the columns for the polymer component and the additive show the blending ratio (unit: parts by mass) of each compound of the polymer component and the additive used for the production of the liquid crystal aligning agent. The numerical values in the solvent column indicate the blending ratio (mass ratio) of each solvent to the total amount of the solvent used for the preparation of the liquid crystal aligning agent. The solvent is simply referred to as follows.

PGME: propylene glycol monomethyl ether

EDM: diethylene glycol methyl ethyl ether

CPN: cyclopentanone

MB: 3-methoxy-1-butanol

NMP: n-methyl-2-pyrrolidone

BC: gamma-butyrolactone

As shown in table 2, in examples 1 to 10 in which the liquid crystal aligning agent containing the polymer (a) was prepared, the pretilt angle was less than 89 degrees, and the tilt angle of the liquid crystal molecules with respect to the vertical direction was sufficiently increased as compared with comparative examples 1 to 4 in which the polymer (a) was not contained. In examples 1 to 10, the pre-tilt angle was less varied depending on the post-baking temperature. In particular, examples 8 and 9 in which polymers having a photosensitive structure were blended, and example 10 in which additives having a photosensitive structure were blended, the evaluation of the post-baking margin was "excellent", and particularly excellent. Further, the coating uniformity of the liquid crystal aligning agents of examples 1 to 10 was also good. Further, it was found that the use of the ring-opened body as the monomer (R1) can improve the coating uniformity.

From these results, it was found that by using the polymer (a), a liquid crystal alignment film having good coating uniformity and excellent pretilt angle characteristics can be formed.

Claims (11)

1. A liquid crystal aligning agent comprising a polymer (A) having a structural unit derived from at least one monomer selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2),

[ solution 1]

(in the formulae (1) and (2), R¹And R²Represents R¹And R²One is a monovalent group having a polymerizable group, the other is a hydrogen atom or a monovalent organic group, or R¹And R²Are bonded to each other to R¹And R²A ring structure formed by the bonded nitrogen atoms; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; a. the¹Is a monovalent organic radical, A²Is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0 ≦ n1+ n2 ≦ 8).

2. The liquid crystal aligning agent according to claim 1, wherein A is¹Is a monovalent group having a photo-alignment group.

3. The liquid crystal aligning agent according to claim 1 or 2, further comprising a polymer (B) which is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and polyurea.

4. The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the polymer (A) has a structural unit derived from a monomer having at least one selected from the group consisting of a cyclic ether structure and a cyclic carbonate structure.

5. The liquid crystal aligning agent according to any one of claims 1 to 4, wherein the polymer (A) has a structural unit derived from a monomer having at least one selected from the group consisting of a carboxyl group and a protected carboxyl group.

6. The liquid crystal aligning agent according to any one of claims 1 to 5, comprising, as the polymer (A) or an additive component, a compound having a partial structure capable of exhibiting a photosensitizing function that exhibits a photosensitizing effect by light irradiation.

7. A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of claims 1 to 6.

8. A liquid crystal cell comprising the liquid crystal alignment film according to claim 7.

9. A polymer having a structural unit derived from at least one monomer selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2),

[ solution 2]

(in the formulae (1) and (2))，R¹And R²Represents R¹And R²One is a monovalent group having a polymerizable group, the other is a hydrogen atom or a monovalent organic group, or R¹And R²Are bonded to each other to R¹And R²A ring structure formed by the bonded nitrogen atoms; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; a. the¹Is a monovalent organic radical, A²Is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0 ≦ n1+ n2 ≦ 8).

10. A compound represented by the following formula (1),

[ solution 3]

(in the formula (1), R¹And R²Represents R¹And R²One is a monovalent group having a polymerizable group, the other is a hydrogen atom or a monovalent organic group, or R¹And R²Are bonded to each other to R¹And R²A ring structure formed by the bonded nitrogen atoms; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; a. the¹Is a monovalent organic group; n1 and n2 are each independently an integer satisfying 0 ≦ n1+ n2 ≦ 8).

11. A compound represented by the following formula (2),

[ solution 4]

(in the formula (2), R¹And R²Represents R¹And R²One is a monovalent group having a polymerizable group, the other is a hydrogen atom or a monovalent organic group, or R¹And R²Are bonded to each other to R¹And R²Rings formed together by the bound nitrogen atomsStructure; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; a. the¹Is a monovalent organic radical, A²Is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0 ≦ n1+ n2 ≦ 8).