JP2022027233A - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal element - Google Patents

Abstract

To provide a liquid crystal aligning agent which offers superior coatability to base materials.SOLUTION: A liquid crystal aligning agent provided herein contains 50 mass% or more of a polymer [A] having a structural unit derived from a monomer having a polymerizable carbon-carbon unsaturated bond with respect to a total amount of the polymer component, and a compound [B] represented by the following formula (1): R1-OH ...(1), where in the formula (1), R1 represents a linear alkyl group having five or more carbon atoms.SELECTED DRAWING: None

Description

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

In recent years, liquid crystal elements have been used not only in display devices such as personal computers, liquid crystal televisions, car navigation systems, mobile phones, smartphones, and information displays, but also in various applications such as optical compensation films and dimming films. Has been done. With such versatility, further improvement in quality of liquid crystal elements is required, and along with improvements in drive methods and element structures, improvements in liquid crystal alignment films, which are one of the constituent members of liquid crystal elements, are being promoted. ing.

The liquid crystal alignment film is usually formed by dissolving a polymer component in a solvent to prepare a polymer composition, and applying the prepared polymer composition on a substrate to remove the solvent. Regarding the polymer component of the liquid crystal alignment agent, the reason is that polyimide and its precursor, polyamic acid, can form a liquid crystal alignment film having high heat resistance and excellent durability, and have good affinity with liquid crystal. Therefore, it has been widely used as an alignment film material (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-112197

Since polyimide and polyamic acid do not have very good solubility, when polyimide or the like is used as a polymer component, a protic polar solvent such as N-methyl-2-pyrrolidone (NMP) is often used as a solvent. However, protic and aprotic solvents generally have a high boiling point and require firing at a relatively high temperature when forming a liquid crystal alignment film. Therefore, there may be disadvantages such as limitation of the type of the base material and an increase in energy cost. Therefore, as the alignment film material, a new material that replaces polyimide is required.

Further, in recent years, with the increase in definition of liquid crystal elements, the demand for display quality has become more stringent, and it is required to suppress defects such as cissing and unevenness that are likely to occur in contact holes formed on a base material as much as possible. Has been done.

The present invention has been made in view of the above problems, and one object of the present invention is to provide a liquid crystal alignment agent having excellent coatability on a substrate.

The present invention employs the following means to solve the above problems.

<1> The polymer [A] containing a structural unit derived from a monomer having a polymerizable carbon-carbon unsaturated bond is 50% by mass or more based on the total amount of the polymer components, according to the following formula (1). A liquid crystal aligning agent containing the represented compound [B].
R ¹ -OH ... (1)
(In the formula (1), R ¹ is a linear alkyl group having 5 or more carbon atoms.)
<2> A liquid crystal alignment film formed by using the liquid crystal alignment agent of <1> above.
<3> A liquid crystal element provided with the liquid crystal alignment film of <2> above.

According to the present invention, it is possible to provide a liquid crystal alignment agent having excellent coatability on a substrate.

Hereinafter, each component contained in the liquid crystal alignment agent of the present disclosure, and other components optionally blended will be described.

In addition, in this specification, a "hydrocarbon group" means a chain hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group. The "chain hydrocarbon group" means a linear hydrocarbon group and a branched hydrocarbon group which do not contain a cyclic structure in the main chain and are composed only of a chain structure. However, it may be saturated or unsaturated. The "alicyclic hydrocarbon group" means a hydrocarbon group containing only the alicyclic hydrocarbon structure as the ring structure and not containing the aromatic ring structure. However, it does not have to be composed only of the alicyclic hydrocarbon structure, and some of them have a chain structure. The "aromatic hydrocarbon group" means a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure, and may include a chain structure or an alicyclic hydrocarbon structure as a part thereof.

The liquid crystal alignment agent of the present disclosure contains a polymer component and a solvent component, and is preferably a polymer composition in which the polymer component is dissolved in the solvent component. The liquid crystal alignment agent of the present disclosure contains the polymer [A] and the compound [B] shown below.

<< Polymer [A] >>
The liquid crystal alignment agent of the present disclosure contains a polymer [A] containing a structural unit derived from a monomer having a polymerizable carbon-carbon unsaturated bond (hereinafter, also referred to as “monomer (M)”) as a polymer component. ] Is contained. The polymer [A] may be composed of one kind of polymer or two or more kinds of polymers.

Examples of the monomer (M) include (meth) acrylic compounds, aromatic vinyl compounds, conjugated diene compounds, maleimide compounds, vinyl compounds and the like. From the viewpoint of obtaining an alignment film having high transparency, high material strength, and high affinity with liquid crystal, the polymer [A] preferably contains a structural unit derived from a (meth) acrylic compound, and is preferably (meth) acrylic. It is more preferable to include a structural unit derived from the compound and a structural unit derived from the maleimide compound. In addition, in this specification, "(meth) acrylic" means to include "acrylic" and "methacrylic".

In the polymer [A], the ratio of the structural units derived from the (meth) acrylic compound may be 25 mol% or more with respect to all the structural units constituting the polymer [A] contained in the liquid crystal aligning agent. It is more preferably 30 mol% or more, and even more preferably 40 mol% or more.
The ratio of the structural unit derived from the maleimide compound is preferably 1 mol% or more, preferably 2 mol% or more, based on all the structural units constituting the polymer [A] contained in the liquid crystal alignment agent. More preferably, it is more preferably 5 mol% or more. The ratio of the structural units derived from the maleimide compound is preferably 50 mol% or less, preferably 40 mol% or less, based on all the structural units constituting the polymer [A] contained in the liquid crystal alignment agent. Is more preferable.

In the present specification, the ratio of the polymer [A] contained in the liquid crystal alignment agent to all the structural units is 2 when two or more kinds of the polymer [A] are contained in the liquid crystal alignment agent. It represents the ratio of the polymer [A] of the species or more to all the structural units. Therefore, for example, when the polymer [A] contains a first polymer containing a structural unit derived from a maleimide compound at a ratio of 10 mol% and a second polymer having no maleimide compound, the first layer is used. If the blending ratio of the coalescence and the second polymer is 1: 9, the ratio of the structural unit derived from the maleimide compound in the polymer [A] is (10/100) × (1/10) + (0 /). 100) × (9/10) = 0.01, that is, 1 mol%.

The polymer [A] may be any polymer obtained by polymerization using the monomer (M), and the monomer composition is not particularly limited. Considering that the liquid crystal alignment film is imparted with good liquid crystal orientation, the liquid crystal alignment agent of the present disclosure is composed of a group consisting of a photoalignant group, a liquid crystal oriented group and a liquid crystal side chain as the polymer [A]. It is preferable to include a polymer having at least one selected (hereinafter, also referred to as “specific structure”). The polymer [A] having a specific structure (hereinafter, also referred to as “polymer [A1]”) tends to have low solubility due to its rigid structure, whereas the compound [B] is used as at least a part of the solvent component. According to the liquid crystal alignment agent of the present disclosure used, even when the polymer [A] has a specific structure, the polymer [A] can be sufficiently dissolved, and a liquid crystal alignment agent having excellent coatability can be obtained. Is preferable.

（式（５）中、Ｘ^１１及びＸ^１２は、それぞれ独立に、水素原子、ハロゲン原子、シアノ基、炭素数１～５のアルキル基、又は炭素数１～５のフルオロアルキル基である。Ｒ^１０は、置換若しくは無置換の炭素数１～１０のアルキル基、置換若しくは無置換の炭素数１～１０のアルコキシ基、フッ素原子、又はシアノ基である。ａは０～４の整数である。ａが２以上の場合、複数のＲ^１０は、同一の基又は異なる基である。「＊」は結合手を示す。） -Photo-orientation group As the photo-orientation group contained in the polymer [A], anisotropy can be imparted to the film by a photoisomerization reaction, a photodimerization reaction, a photofleece rearrangement reaction or a photodecomposition reaction by light irradiation. Functional groups can be used. Specific examples of the photoorienting group include an azobenzene-containing group containing azobenzene or a derivative thereof as a basic skeleton, a keishide structure-containing group containing keiseki acid or a derivative thereof (keiseki acid structure) as a basic skeleton, a chalcone or a derivative thereof. A chalcone-containing group containing benzophenone or a derivative thereof as a basic skeleton, a phenylbenzoate-containing group containing phenylbenzoate or a derivative thereof as a basic skeleton, a coumarin-containing group containing coumarin or a derivative thereof as a basic skeleton, Examples thereof include a cyclobutane-containing structure containing cyclobutane or a derivative thereof as a basic skeleton. Of these, the photo-oriented group is particularly preferably a cinnamic acid structure-containing group in terms of high sensitivity to light and easy introduction into the polymer side chain. The cinnamic acid structure-containing group is preferably a group containing a cinnamic acid structure represented by the following formula (5) as a basic skeleton.

In formula (5), X ¹¹ and X ¹² are independently hydrogen atoms, halogen atoms, cyano groups, alkyl groups having 1 to 5 carbon atoms, or fluoroalkyl groups having 1 to 5 carbon atoms. Reference numeral ¹⁰ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a fluorine atom, or a cyano group. A is an integer of 0 to 4. When a is 2 or more, a plurality of R ^10s are the same group or different groups. “*” Indicates a bond.)

In the above formula (5), examples of the substituent contained in the substituted alkyl group having 1 to 10 carbon atoms and the substituted alkoxy group having 1 to 10 carbon atoms include a fluorine atom and a cyano group.
As the group represented by the above formula (5), a monovalent group obtained by removing one hydrogen atom of the carboxyl group of cinnamic acid, or a substituent is introduced into the benzene ring of the monovalent group. A monovalent group or a monovalent group obtained by esterifying the above-mentioned group (hereinafter also referred to as "forward cinnamate group") and the carboxyl group of cinnamic acid and binding a divalent organic group to the benzene ring. Examples thereof include a group in which a substituent is introduced into the benzene ring of the group (hereinafter, also referred to as “reverse cinnamate group”).
In the above formula (5), X ¹¹ and X ¹² are preferably a hydrogen atom, a fluorine atom, a cyano group or an alkyl group having 1 to 3 carbon atoms. 0 or 1 is preferable for a, and 0 is particularly preferable.

（式（５－１）中、Ｒ^１４は、水素原子、ハロゲン原子、炭素数１～２０のアルキル基、炭素数１～２０のアルコキシ基又はシアノ基である。Ｒ^１５は、フェニレン基、ビフェニレン基、ターフェニレン基若しくはシクロヘキシレン基、又はこれらの基が有する水素原子の少なくとも一部が、ハロゲン原子、シアノ基、炭素数１～１０のアルキル基、炭素数１～１０のアルコキシ基、又は当該アルコキシ基の水素原子の少なくとも一部がハロゲン原子で置換された１価の基によって置換された基である。Ａ^１は、単結合、酸素原子、硫黄原子、炭素数１～３のアルカンジイル基、－ＣＨ＝ＣＨ－、－ＮＨ－、＊^１－ＣＯＯ－、＊^１－ＯＣＯ－、＊^１－ＮＨ－ＣＯ－、＊^１－ＣＯ－ＮＨ－、＊^１－ＣＨ_２－Ｏ－又は＊^１－Ｏ－ＣＨ_２－（「＊^１」はＲ^１５との結合手を示す。）である。ｂは０又は１である。
式（５－２）中、Ｒ^１６は、水素原子、炭素数１～２０の１価の炭化水素基、又は当該炭化水素基が有する水素原子の少なくとも一部がアルコキシ基、ハロゲン原子若しくはシアノ基で置換された１価の基である。
式（５－１）及び式（５－２）中のＸ^１１、Ｘ^１２、Ｒ^１０及びａは、上記式（５）と同義である。「＊」は結合手であることを示す。） The forward cinnamate group can be represented by, for example, the following formula (5-1), and the reverse cinnamate group can be represented by, for example, the following formula (5-2).

(In the formula (5-1), R ¹⁴ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group or a cyano group having 1 to 20 carbon atoms, and R ¹⁵ is a phenylene group or biphenylene. A group, a terphenylene group or a cyclohexylene group, or at least a part of hydrogen atoms contained in these groups is a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or the same. At least a part of the hydrogen atom of the alkoxy group is substituted with a monovalent group substituted with a halogen atom. A ¹ is a single bond, an oxygen atom, a sulfur atom and an alkanediyl group having 1 to 3 carbon atoms. , -CH = CH-, -NH-, * ^{1-COO-, * 1 -} OCO-, * ¹ -NH-CO-, * ¹ -CO-NH-, * ¹ -CH ₂ -O- or * ¹ -O-CH _2- ("* ¹ " indicates a bond with R ¹⁵ ). B is 0 or 1.
^In the formula (5-2), in R16, at least a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or at least a part of the hydrogen atom contained in the hydrocarbon group is an alkoxy group, a halogen atom or a cyano group. It is a monovalent group substituted with.
X ¹¹ , X ¹² , R ¹⁰ and a in the formula (5-1) and the formula (5-2) have the same meaning as the above formula (5). "*" Indicates that it is a bond. )

-Liquid crystal orientation group A liquid crystal orientation group is a group having a function of vertically or horizontally orienting liquid crystal molecules without being irradiated with light. Examples of the liquid crystal orientation group include an alkyl group having 4 to 20 carbon atoms, an alkoxy group having 4 to 20 carbon atoms, a fluoroalkyl group having 4 to 20 carbon atoms, and a fluoroalkoxy group having 4 to 20 carbon atoms. A group having a structure in which a ring and a chain structure having 1 to 20 carbon atoms are bonded, a group having a structure in which two or more rings are bonded directly or via a divalent linking group, and a group having a steroid skeleton. And so on. Among these, the liquid crystal orientation group is preferably a group represented by the following formula (6).
* -L ³¹ -R ³¹ -R ^32- R ³³ -R ³⁴ ... (6)
(In the formula (6), L ³¹ is a single bond, -O-, -CO-, -COO- * ¹ , ^-OCO- * ¹ , -NR 35-, -NR ³⁵ -CO- * ¹ , -CO. -NR ^35- * ¹ , a divalent group in which the hydrogen atom of an alkanediyl group having 1 to 6 carbon atoms and an alkanediyl group having 2 to 6 carbon atoms is substituted with a hydroxyl group, -OR ^36- * ¹ , Or -R ³⁶ -O- * ¹ (where R ³⁵ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R ³⁶ is an alkanediyl group having 1 to 3 carbon atoms. ¹ ”indicates that it is a bond with R ^31. ) R ³¹ and R ³³ are independently single-bonded, substituted or unsubstituted phenylene groups, or substituted or unsubstituted cycloalkylenes, respectively. R ³² is a single bond, substituted or unsubstituted phenylene group, substituted or unsubstituted cycloalkylene group, or -R ³⁷ -B ³¹ -R ^38- (where R ³⁷ and R ³⁸ are, respectively. Independently substituted or unsubstituted phenylene group or cycloalkylene group, B ³¹ is a single bond, -O-, -COO- * ² , -OCO- * ² , -OCH _2- * ² , -CH ₂ O. -* ² or an alkanediyl group having 1 to 3 carbon atoms. "* ² " indicates that it is a bond with R ^38. ) R ³⁴ is a hydrogen atom, a fluorine atom, or a cyano. Group, CH ₃ COO- * ³ (“* ³ ” indicates a bond with R ³³ ), an alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, and a carbon number of carbon atoms. An alkoxy group having 1 to 18, a fluoroalkoxy group having 1 to 18 carbon atoms, a hydrocarbon group having a steroid skeleton and having 17 to 51 carbon atoms, or an alkyl group having 1 to 18 carbon atoms or a hydrogen atom having a fluoroalkyl group. It is a monovalent group substituted with a cyano group, provided that all of R ³¹ , R ³² and R ³³ are single bonds, or the substituted or unsubstituted phenylene group of R ³¹ , R ³² and R ³³ . And when the total number of cycloalkylene groups is 1, R ³⁴ has an alkyl group having 4 to 18 carbon atoms, a fluoroalkyl group having 4 to 18 carbon atoms, an alkoxy group having 4 to 18 carbon atoms, and 4 to 18 carbon atoms. Is a fluoroalkoxy group or a hydrocarbon group having a steroid skeleton and having 17 to 51 carbon atoms. "*" Indicates a bond.)

In the above formula (6), the alkanediyl group of L ³¹ is preferably linear. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms of ^R35 include a chain hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group, and an alkyl group having 1 to 3 carbon atoms is preferable. Is.
For R ³⁴ , an alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a fluoroalkoxy group having 1 to 18 carbon atoms, or an alkyl having 1 to 18 carbon atoms. The monovalent group in which the hydrogen atom of the group or fluoroalkyl group is substituted with a cyano group is preferably linear. These groups preferably have 2 to 18 carbon atoms, more preferably 3 to 18 carbon atoms, and even more preferably 4 to 18 carbon atoms when the liquid crystal element is vertically oriented. Examples of the hydrocarbon group having a steroid skeleton of R ³⁴ and having 17 to 51 carbon atoms include a cholestanyl group, a cholesteryl group, a lanostannyl group and the like.

（式（６－１）～式（６－１０）中、Ｒ^２０は、フッ素原子、シアノ基、炭素数１～２０のアルキル基、炭素数１～２０のフルオロアルキル基、炭素数１～２０のアルコキシ基、又は炭素数１～２０のフルオロアルコキシ基である。Ｘ^２１は、－Ｏ－、－ＣＯＯ－又は炭素数１～３のアルカンジイル基である。「＊」は結合手であることを表す。） As the liquid crystal orientation group, from the viewpoint of obtaining a liquid crystal element showing good liquid crystal orientation, R ³¹ , R ³² and R ³³ have at least two substituted or unsubstituted phenylene groups and cycloalkylene groups in total. It is preferable that the group has 2 to 4 groups in total.
Specific examples of the liquid crystal orientation group include groups represented by the following formulas (6-1) to (6-10).

(In formulas (6-1) to (6-10), R ²⁰ is a fluorine atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, a fluoroalkyl group having 1 to 20 carbon atoms, and 1 to 20 carbon atoms. Alkoxy group or fluoroalkoxy group having 1 to 20 carbon atoms. X ²¹ is an -O-, -COO- or an alkanediyl group having 1 to 3 carbon atoms. "*" Is a bond. Represents.)

（式（７－１）～式（７－８）中、Ａ^２及びＡ^５は、それぞれ独立に、単結合、－Ｏ－、－ＣＨ_２－、－ＣＯＯ－、－ＣＯＮＨ－、又は－ＣＨ＝ＣＨ－ＣＯ－Ｏ－である。Ａ^３は、環構造を有する１価の基である。Ａ^４は、水素原子、ニトロ基、シアノ基、－ＣＨ＝Ｃ（ＣＮ）_２、－ＣＨ＝ＣＨ－ＣＮ、ハロゲン原子、炭素数１～２０の１価の炭化水素基、１価の複素環基、又は炭素数１～２０のアルコキシ基である。Ｘ^３は、単結合、－ＣＯ－、－ＣＨ_２Ｏ－、－ＣＨ＝Ｎ－、又は－ＣＦ_２－である。ａ１及びａ２は、一方が０で他方が１である。ｃ１は、それぞれ０～３の整数である。ｂ１は１～１２の整数である。ただし、式（７－２）及び式（７－３）では、ｃ１の合計が２以上である。式（７－４）及び式（７－５）では、ｃ１の合計が１以上である。「＊」は結合手であることを表す。） Liquid crystal side chain The liquid crystal side chain has a side chain structure that enables the polymer [A] to exhibit liquid crystallinity in a predetermined temperature range (preferably, a temperature range of 100 to 300 ° C.). Specific examples of the liquid crystal side chain include partial structures represented by the following formulas (7-1) to (7-8).

(In formulas (7-1) to (7-8), A ² and A ⁵ are independently single-bonded, -O-, -CH _2- , -COO-, -CONH-, or -CH. = CH-CO-O-. A ³ is a monovalent group having a ring structure. A ⁴ is a hydrogen atom, a nitro group, a cyano group, -CH = C (CN) ₂ , -CH =. CH-CN ^, a halogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent heterocyclic group, or an alkoxy group having 1 to 20 carbon atoms. -CH ₂ O-, -CH = N-, or -CF _2- . One and a2 are 0 and the other is 1. c1 is an integer of 0 to 3, respectively. B1 is 1. It is an integer of ~ 12. However, in the formula (7-2) and the formula (7-3), the total of c1 is 2 or more. In the formula (7-4) and the formula (7-5), the total of c1 is 2. The total is 1 or more. "*" Indicates that it is a bond.)

The polymer [A1] can be obtained, for example, by polymerizing using a monomer having a specific structure. Examples of the monomer having a specific structure include (meth) acrylic compounds, styrene compounds, maleimide compounds and the like. In the polymer [A1], the content ratio of the structural units having a specific structure is preferably 1 mol% or more, preferably 2 mol% or more, based on all the structural units constituting the polymer [A1]. Is more preferable, and 5 mol% or more is further preferable. The content ratio of the structural unit (X) is preferably 50 mol% or less, more preferably 40 mol% or less, based on all the structural units constituting the polymer [A1].

The liquid crystal alignment agent of the present disclosure may contain a polymer having no specific structure (hereinafter, also referred to as “polymer [A2]) as the polymer [A]. In particular, the polymer [A] is specified. It is preferable to include the polymer [A1] having a structure and the polymer [A2] having no specific structure in that the solubility in the compound [B] can be enhanced and the coatability of the liquid crystal alignment agent can be further enhanced. ..

When the polymer [A1] and the polymer [A2] are contained in the liquid crystal alignment agent, the content ratio of the polymer [A1] is contained in the liquid crystal alignment agent from the viewpoint of obtaining a liquid crystal alignment film having good liquid crystal alignment. It is preferably 1% by mass or more, and more preferably 2% by mass or more, based on the total amount of the polymer [A]. Further, the content ratio of the polymer [A1] may be 40% by mass or less with respect to the total amount of the polymer [A] contained in the liquid crystal alignment agent from the viewpoint of suppressing the deterioration of the coatability. It is preferably 30% by mass or less, more preferably 30% by mass or less.

-Crosslinkable group At least a part of the polymer [A] contained in the liquid crystal alignment agent may have a crosslinkable group. When the polymer [A] having a crosslinkable group is used, it is preferable in that the coatability of the liquid crystal alignment agent and the electrical characteristics of the liquid crystal element can be improved in a well-balanced manner.

Examples of the crosslinkable group include an epoxy group, a cyclic carbonate group, an isocyanate group, a protected isocyanate group, an oxazoline group, a β-hydroxyalkylamide group, a merdamic acid group, a methylol group, an alkylmethylol group, a hydroxyl group, a protected hydroxyl group, and the like. Examples thereof include a carboxyl group, a protected carboxyl group (hereinafter, also referred to as “protected carboxyl group”), an amino group, a protected amino group, a vinyl group, an allyl group, a (meth) acryloyl group, an alkoxysilyl group and the like. In addition, in this specification, an epoxy group is meant to include an oxetanyl group and an oxylanyl group. The crosslinkable group is composed of an epoxy group, a protected isocyanate group, an oxazoline group, a methylol group, a carboxyl group, and a protected carboxyl group because of its high thermal reactivity and good storage stability. At least one selected is preferable, and it is particularly preferable to contain an epoxy group.

The crosslinkable group may be contained only in the polymer [A1], may be contained only in the polymer [A2], and may be contained in both the polymer [A1] and the polymer [A2]. You may. It is preferable that at least the polymer [A1] has a crosslinkable group, and the polymer [A1] and the polymer [A1] and It is more preferable that both of the polymers [A2] have.

The polymer [A] having a crosslinkable group can be obtained, for example, by polymerizing using a monomer having a crosslinkable group. In the polymer [A], the content ratio of the structural unit having a crosslinkable group is preferably 10 mol% or more with respect to all the structural units constituting the polymer [A] contained in the liquid crystal alignment agent. , 20 mol% or more is more preferable, and 30 mol% or more is further preferable. The content ratio of the structural unit having a crosslinkable group is preferably 99 mol% or less, preferably 95 mol% or less, based on all the structural units constituting the polymer [A] contained in the liquid crystal alignment agent. Is more preferable.

In a preferred embodiment when the polymer [A] has a crosslinkable group, the polymer [A] has a ring structure Q of at least one of an oxetane ring and an oxylan ring and a functional group that reacts with the ring structure Q by heating. Is contained in the same polymer or different polymers. In this case, it is preferable in that the coatability of the liquid crystal alignment agent can be improved while maintaining a high voltage retention rate of the liquid crystal element.

The ring structure of the polymer [A] is preferably an oxetane ring in that it has high reactivity, and an oxylan ring is preferable in that it has a high degree of freedom in selecting a monomer.
Examples of the functional group that reacts with the ring structure Q include a carboxyl group, a hydroxyl group, an isocyanate group and an amino group, a group in which each of these groups is protected by a protecting group, an alkoxymethyl group and the like. Of these, the functional group that reacts with the ring structure Q is superior to the carboxyl group and the protective carboxyl group in that the storage stability of the liquid crystal alignment agent can be improved and the reactivity with the oxetane ring and the oxylan ring by heating is high. It is preferable that it is at least one selected from the group.

The ring structure Q may be contained only in the polymer [A1], may be contained only in the polymer [A2], and may be contained in both the polymer [A1] and the polymer [A2]. You may. Similarly, the functional group that reacts with the ring structure Q may have only the polymer [A1] or only the polymer [A2], and may have the polymer [A1] and the weight. Both of the coalescing [A2] may have. It is preferable that at least the polymer [A2] has a ring structure Q and a functional group that reacts with the ring structure Q in that the voltage retention rate can be increased, and both the polymer [A1] and the polymer [A2] contain. It is more preferable to have a ring structure Q and a functional group that reacts with the ring structure Q.

Specific examples of the compound having a ring structure Q include glycidyl (meth) acrylate, glycidyl α-ethyl acrylate, glycidyl α-n-propyl acrylate, glycidyl α-n-butyl acrylate, and (meth) acrylic. Acids 3,4-epoxybutyl, α-ethylacrylic acid 3,4-epoxybutyl, (meth) acrylic acid 3,4-epoxycyclohexylmethyl, (meth) acrylic acid 6,7-epoxyheptyl, α-ethylacrylic acid (Meta) acrylic compounds such as 6,7-epoxyheptyl, 4-hydroxybutylglycidyl ether acrylate, (meth) acrylic acid (3-ethyloxetane-3-yl) methyl; 4-vinyl-1-glycidyloxymethylbenzene , 3-Vinyl-1-glycidyloxymethylbenzene and the like. As the monomer having a ring structure Q, one of these may be used alone, or two or more thereof may be used in combination.

（式（ｍ－１）～式（ｍ－７）中、Ｒは、水素原子又はメチル基である。）
のそれぞれで表される保護カルボニル基含有化合物等が挙げられる。当該単量体としては、１種を単独で又は２種以上を組み合わせて使用することができる。 Specific examples of the monomer having a functional group that reacts with the ring structure Q include (meth) acrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, vinyl benzoic acid, crotonic acid, citraconic acid, and mesaconic acid. Carboxylic acid-containing compounds such as itaconic acid, 3-maleimide benzoic acid, 3-maleimide propionic acid; unsaturated polyvalent carboxylic acid anhydrides such as maleic anhydride; the following formulas (m-1) to (m-7).

(In the formulas (m-1) to (m-7), R is a hydrogen atom or a methyl group.)
Examples thereof include a protected carbonyl group-containing compound represented by each of the above. As the monomer, one type can be used alone or two or more types can be used in combination.

In the polymer [A], the content ratio of the structural units derived from the monomer having the ring structure Q is 1 to 90 mol with respect to all the structural units constituting the polymer [A] contained in the liquid crystal aligning agent. %, More preferably 5 to 90 mol%, still more preferably 10 to 80 mol%.
The content ratio of the structural unit derived from the monomer having a functional group that reacts with the ring structure Q shall be 1 to 90 mol% with respect to the total structural unit of the polymer [A] contained in the liquid crystal alignment agent. It is preferably 5 to 90 mol%, more preferably 10 to 80 mol%, and even more preferably 10 to 80 mol%.

The polymer [A] may be a monomer having no specific structure or a crosslinkable group (hereinafter, also referred to as “another monomer”) as a monomer [M] as long as the effects of the present disclosure are not impaired. It may have a structural unit of origin. Specific examples of other monomers include (meth) acrylic compounds such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and -2-ethylhexyl (meth) acrylate. , (Meta) cyclohexyl acrylate, (meth) phenyl acrylate, unsaturated carboxylic acid ester such as (meth) benzyl acrylate, etc.;
Aromatic vinyl compounds include styrene, methylstyrene, divinylbenzene and the like; conjugated diene compounds include, for example, 1,3-butadiene, 2-methyl-1,3-butadiene; maleimide compounds include maleimide, N-methyl. Maleimide, N-cyclohexylmaleimide, N-phenylmaleimide and the like; examples of the vinyl compound include methyl vinyl ether, benzyl vinyl ether and the like, respectively. As the monomer [M], one type may be used alone, or two or more types may be used in combination.

The polymer [A] can be obtained by polymerizing the monomer [M] in the presence of a polymerization initiator using a known method such as radical polymerization. The polymerization initiators used are 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2'-azobis (4-methoxy-2,4). -Azobis compound such as dimethylvaleronitrile) is preferable. The proportion of the polymerization initiator used is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of the total amount of the monomers used in the reaction.

The polymerization reaction 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. The reaction temperature is, for example, 30 ° C to 120 ° C. The reaction time is, for example, 1 to 36 hours. The amount (a) of the organic solvent used should be such that the total amount (b) of the monomers used in the reaction is 0.1 to 60% by mass with respect to the total amount (a + b) of the reaction solution. Is preferable.

When synthesizing a polymer having a specific structure in a side chain as the polymer [A], the synthesizing method is not particularly limited. As a method for synthesizing a polymer having a specific structure, for example, a method of polymerizing using a monomer having a specific structure; an epoxy group-containing monomer is used as at least a part of a raw material, and an epoxy group is side-chained. Examples thereof include a method of synthesizing a polymer having a specific structure and then reacting with a carboxylic acid having a specific structure.

The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the polymer [A] is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. Is. The molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC is preferably 8 or less, more preferably 6 or less. In preparing the liquid crystal alignment agent, the polymer [A] may be used alone or in combination of two or more.

In the liquid crystal alignment agent of the present disclosure, the content ratio of the polymer [A] is 50% by mass or more with respect to the total amount of the polymer components contained in the liquid crystal alignment agent. The content ratio of the polymer [A] is preferably 70% by mass or more, more preferably 80% by mass or more, and 90% by mass or more, based on the total amount of the polymer components contained in the liquid crystal alignment agent. It is more preferably 95% by mass or more, further preferably 99% by mass or more, and particularly preferably 99% by mass or more.

The liquid crystal alignment agent of the present disclosure may contain a polymer other than the polymer [A] (hereinafter, also referred to as “another polymer”) as a polymer component. Examples of other polymers include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamideimide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal and the like. Be done. As the other polymer, one kind may be contained alone, or two or more kinds may be contained.

The content ratio of the other polymer in the liquid crystal alignment agent is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total amount of the polymer components contained in the liquid crystal alignment agent. It is more preferably 0% by mass or less, further preferably 5% by mass or less, and particularly preferably 1% by mass or less.

<Compound [B]>
Compound [B] is a compound represented by the following formula (1). The surface tension of the compound [B] is moderately low, and by using such the compound [B] as a solvent component for dissolving the polymer [A], a liquid crystal alignment agent having good coatability on a substrate can be obtained. ..
R ¹ -OH ... (1)
(In the formula (1), R ¹ is a linear alkyl group having 5 or more carbon atoms.)

Compound [B] is a primary alcohol or a secondary alcohol having a linear alkyl chain. Here, "the alkyl chain is linear" means that there is no branch in the alkyl chain.
From the viewpoint of suppressing the generation of repellency, suppressing the decrease in wettability, and ensuring the ease of use as a solvent with an appropriately low melting point, the carbon number of R ¹ in the above formula (1) is 5 to 5. 20 is preferable, 5 to 15 is more preferable, 5 to 12 is further preferable, and 5 to 10 is particularly preferable.

Specific examples of R ¹ include 1-pentyl group, 2-pentyl group, 3-pentyl group, 1-hexyl group, 2-hexyl group, 1-heptyl group, 2-heptyl group, 3-heptyl group, 4-. Heptyl group, 1-octyl group, 2-octyl group, 3-octyl group, 4-octyl group, 1-nonyl group, 2-nonyl group, 1-decyl group, 2-decyl group, 1-undecyl group, 2- Undecyl group, 1-dodecyl group, 2-dodecyl group, 1-tridecyl group, 2-tridecyl group, 1-tetradecyl group, 2-tetradecyl group, 1-pentadecyl group, 2-pentadecyl group, 1-hexadecyl group, 2- Examples thereof include a hexadecyl group, a 1-heptadecyl group, a 2-heptadecyl group, a 1-octadecyl group, a 2-octadecyl group, a 1-nonadecil group, a 2-nonadecil group, a 1-icosyl group and a 2-icosyl group.

Preferred specific examples of the compound [B] include compounds represented by the following formulas (B-1) to (B-51).

In the liquid crystal alignment agent, the content ratio of the compound [B] is 1% by mass or more with respect to the total amount of the solvent contained in the liquid crystal alignment agent from the viewpoint of sufficiently obtaining the effect of improving the coatability of the liquid crystal alignment agent. Is preferable. The content ratio of the compound [B] is more preferably 3% by mass or more, further preferably 5% by mass or more, and particularly preferably 10% by mass or more. Further, the compound [B] can be used in a range of 100% by mass or less with respect to the total amount of the solvent contained in the liquid crystal alignment agent. The content ratio of the compound [B] is preferably 99% by mass or less, more preferably 95% by mass or less, still more preferably 90% by mass or less, based on the total amount of the solvent contained in the liquid crystal aligning agent. Yes, more preferably 80% by mass or less, further preferably 60% by mass or less, even more preferably 50% by mass or less, and particularly preferably 30% by mass or less. As the compound [B], one type may be used alone, or two or more types may be used in combination.

（式（３）中、Ｒ^５は、炭素数１～３のアルキル基、炭素数１～３のアルコキシ基、又は炭素数２若しくは３のアルコキシアルキル基である。Ｘ^１は、単結合又は酸素原子である。Ｒ^６は、炭素数１～３のアルカンジイル基である。Ｒ^７は、水素原子又は炭素数１～３のアルキル基である。ｍは０又は１である。
式（４）中、Ｒ^８及びＲ^９は、それぞれ独立して、炭素数１～３のアルキル基、炭素数１～３のアルコキシ基、又は炭素数２若しくは３のアルコキシアルキル基である。Ｘ^２は、単結合又は炭素数１若しくは２のアルカンジイル基である。） <Compound [C]>
In the preparation of the liquid crystal aligning agent, only the compound [B] may be used as the solvent component, but the compound represented by the following formula (2) and the compound represented by the following formula (3) together with the compound [B] may be used. , The compound represented by the following formula (4), and at least one compound [C] selected from the group consisting of cyclic ketones having 4 to 7 carbon atoms are preferably used. The combined use of the compound [C] is preferable in that the coatability of the liquid crystal alignment agent to the substrate can be further improved.
R ^2- (OR ³ ) _n -OR ⁴ ... (2)
(In the formula (2), R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ³ is an alkanediyl group having 2 to 4 carbon atoms. R ⁴ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. It is an alkyl group of 1 to 4. n is an integer of 0 to 3. When n is 2 or ³ , a plurality of R3s in the formula are the same group or different groups from each other. N is 0. In this case, R ² is an alkyl group having 3 to 5 carbon atoms, and R ⁴ is a hydrogen atom.)

(In the formula (3), R ⁵ is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or an alkoxyalkyl group having 2 or 3 carbon atoms. X ¹ is a single bond or oxygen. It is an atom. R ⁶ is an alkylandyl group having 1 to 3 carbon atoms. R ⁷ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. M is 0 or 1.
In the formula (4), R ⁸ and R ⁹ are independently an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or an alkoxyalkyl group having 2 or 3 carbon atoms. X ² is a single bond or an alkanediyl group having 1 or 2 carbon atoms. )

(Compound represented by the formula (2))
In the above formula (2), the alkyl group having 1 to 5 carbon atoms of R ² may be linear or branched, and may be, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group or an n-butyl group. Examples thereof include an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group and the like. When n is 1 to 3, R ² is preferably an alkyl group having 1 to 4 carbon atoms. When n is 0, R ² is preferably an n-propyl group, an n-butyl group, an isobutyl group or an isopentyl group.
The alkandyl group having 2 to 4 carbon atoms of R ³ includes an ethylene group, a propylene group, a 1-methylethylene group, a 2-methylethylene group, an n-butylene group, a 2-methylpropylene group and a 2,2-dimethylethylene group. The group etc. can be mentioned. Of these, R ³ preferably has 2 or 3 carbon atoms.
Examples of the alkyl group having 1 to 4 carbon atoms of R ⁴ include those having 1 to 4 carbon atoms among the alkyl groups exemplified in the above description of R ² . ^R4 is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

Specific examples of the compound represented by the above formula (2) include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, and ethylene glycol monobutyl ether (butyl cellosolve). , 3-methoxy-1-butanol, 1,3-butylene glycol, n-propyl alcohol, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol monomethyl ether, Examples thereof include dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycol methyl ether, tripropylene glycol n-butyl ether, ethylene glycol dimethyl ether, and dipropylene glycol dimethyl ether.

(Compound represented by the formula (3))
In the above formula (3), examples of the alkyl group having 1 to ³ carbon atoms of R5 and ^R7 include a methyl group, an ethyl group, an n-propyl group and an isopropyl group. Examples of the alkoxy group and alkylalkoxy group of R ⁵ include a methoxy group, an ethoxy group, a methoxymethyl group, an ethoxyethyl group and the like. Of these, ^R5 is preferably a methyl group or an ethyl group. R ⁷ is preferably a hydrogen atom, a methyl group or an ethyl group.
The alkanediyl group having 1 to 3 carbon atoms of R ⁶ is preferably linear, and a methylene group or an ethylene group is more preferable.

Preferred specific examples of the compound represented by the above formula (3) include diacetone alcohol, 4-methoxy-4-methyl-2-pentanone, and 3-methoxy-3-methylbutyl acetate.

(Compound represented by the formula (4))
In the above formula (4), specific examples of the alkyl group having 1 to ³ carbon atoms of R8 and R9, the alkoxy group having 1 to ³ carbon atoms, and the alkoxyalkyl group having 2 or 3 carbon atoms are described in the above formula (4). ³ ) Examples of the groups exemplified in the explanation of R5 in the above can be mentioned. R ⁸ and R ⁹ are preferably a methoxy group or an ethoxy group.

Specific examples of the compound represented by the above formula (4) include acetone, methyl ethyl ketone, methyl-n-propyl ketone, diethyl ketone, diethyl oxalate, dimethyl dimaronate and the like. Of these, diethyl oxalate and dimethyl dimalonate are preferable.
Examples of the cyclic ketone having 4 to 7 carbon atoms include cyclobutanone, cyclopentanone, cyclohexanone, and cycloheptanone.

Among the above, the compound represented by the above formula (2) can be preferably used as the compound [C]. Among the compounds represented by the above formula (2), diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-1-butanol, 1,3-butylene glycol, n-propyl alcohol, propylene. At least one selected from the group consisting of glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycol methyl ether, and tripropylene glycol n-butyl ether. Is preferable, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-1-butanol, propylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-propyl ether, and di. At least one selected from the group consisting of propylene glycol n-butyl ether is more preferable.

The content ratio of the compound [C] is 5% by mass or more with respect to the total amount of the solvent contained in the liquid crystal alignment agent from the viewpoint of sufficiently obtaining the effect of improving the coatability of the liquid crystal alignment agent on the substrate. preferable. The content ratio of the compound [C] is more preferably 10% by mass or more, further preferably 20% by mass or more, still more preferably 40% by mass or more, and particularly preferably 50% by mass or more. Further, the compound [C] is preferably 99% by mass or less, more preferably 97% by mass or less, still more preferably 95% by mass or less, based on the total amount of the solvent contained in the liquid crystal alignment agent. , More preferably 90% by mass or less. As the compound [C], one type may be used alone, or two or more types may be used in combination.

The liquid crystal alignment agent of the present disclosure may further contain a solvent different from the compound [B] and the compound [C] (hereinafter, also referred to as “another solvent”). As another solvent, a known solvent used for preparing a liquid crystal alignment agent can be used. Specific examples of other solvents include a solvent mainly used for improving the solubility and leveling property of a polymer (hereinafter, also referred to as “first solvent”), and a solvent used for improving wettability and spreading property. (Hereinafter also referred to as "second solvent").

Specific examples of other solvents include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethyl as the first solvent. Acetamide, 4-hydroxy-4-methyl-2-pentanone, 1,3-dimethyl-2-imidazolidinone, etc.;
As the second solvent, an ether solvent such as diisopentyl ether; methyl acetate, ethyl acetate, propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, t-butyl acetate, 3-methoxybutyl acetate, Methyl acetoacetate, ethyl acetoacetate, ethyl propionate, n-butyl propionate, methyl lactate, ethyl lactate, n-butyl lactate, methylmethoxypropionate, ethylethoxypropionate, ethylene glycol ethyl ether acetate, diethylene glycol Ester solvents such as monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol diethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), isoamyl propionate, isoamyl isobutyrate, propylene glycol diacetate; methyl-n-butylketone , Di-n-butylketone, methyl-i-butylketone, methyl-n-pentylketone, ethyl-n-butylketone, methyl-n-hexylketone, diisobutylketone, trimethylnonanone and other ketone solvents can be mentioned. can. As the other solvent, one type may be used alone, or two or more types may be mixed and used.

When another solvent is used as the solvent, the content ratio of the other solvent (the total amount when two or more kinds are used) is preferably 80% by mass or less with respect to the total amount of the solvent contained in the liquid crystal alignment agent. , 50% by mass or less is more preferable, 20% by mass or less is further preferable, and 10% by mass or less is particularly preferable.

From the viewpoint of lowering the heating temperature during film formation, environmental regulation, health effects, etc., the liquid crystal alignment agent of the present disclosure does not substantially contain N-methyl-2-pyrrolidone (NMP). Is preferable. Specifically, the content ratio of NMP in the liquid crystal alignment agent of the present disclosure is preferably 5% by mass or less, and preferably 1% by mass or less, based on the total amount of the solvent contained in the liquid crystal alignment agent. It is more preferably 0.5% by mass or less, and further preferably 0.5% by mass or less.

<Other ingredients>
In addition to the components described above, the liquid crystal alignment agent may further contain a component different from the above component (hereinafter, also referred to as “other component”), if necessary.

<Crosslinking agent>
The liquid crystal alignment agent of the present disclosure may further contain a cross-linking agent as an additive component. When a cross-linking agent is contained, it is preferable in that the electrical characteristics of the liquid crystal element can be improved. As the cross-linking agent, at least one selected from the group consisting of a cyclic ether group, a cyclic carbonate group, an isocyanate group, a protected isocyanate group, an oxazoline group, a β-hydroxyalkylamide group, a merdamic acid group, a methylol group and an alkylmethylol group. It is preferable that the compound has a cross-linking group of 1000 or less and has a molecular weight of 1000 or less. The number of crosslinkable groups per molecule of the cross-linking agent is preferably 2 or more, and more preferably 3 or more. The cross-linking agent is preferably a compound having at least one selected from the group consisting of a cyclic ether group, a protected isocyanate group, a β-hydroxyalkylamide group, a methylol group and an alkylmethylol group, preferably a protected isocyanate group and β. -A compound having at least one selected from the group consisting of a hydroxyalkylamide group, a methylol group and an alkylmethylol group is more preferable.

Specific examples of the cross-linking agent include, for example, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N, N, as compounds having a cyclic ether group. N', N'-tetraglycidyl-m-xylene diamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-4,4'-diamino Diphenylmethane, N, N-diglycidyl-benzylamine, N, N-diglycidyl-aminomethylcyclohexane, N, N-diglycidyl-cyclohexylamine and the like; as compounds having a cyclic carbonate group, for example, N, N, N', N' -Tetra [(2-oxo-1,3-dioxolan-4-yl) ethyl] -4,4'-diaminodiphenylmethane, etc.;
Compounds having an isocyanate group or a protected isocyanate group include, for example, tolylene diisocyanate, xylylene diisocyanate, chlorphenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and polyvalent isocyanates thereof. Protected isocyanate compounds protected with a protective group; examples of compounds having an oxazoline group include 2,2'-bis (4-propyl-2-oxazoline) and 2,2'-bis (4-phenyl-2-oxazoline). ), 1,2-Bis (2-oxazoline-2-yl) ethane, 1,4-bis (2-oxazoline-2-yl) cyclohexane, 1,3-bis (2-oxazoline-2-yl) benzene, 1,3-Bis (4,5-dihydro-2-oxazolyl) benzene, 1,3-bis (4-methyl-2-oxazolin-2-yl) benzene, etc.; as compounds having a β-hydroxyalkylamide group. For example, N, N, N', N'-tetrakis (2-hydroxyethyl) adipamide and the like; as a compound having a methylol group or an alkylmethylol group, for example, trimethylolpropane, bis [2-ethyl-2,2-bis (Hydroxymethyl) ethyl] ether, 2,2'-[oxybis (methylene)] bis [2-ethyl-1,3-propanediol], 2,2-bis (4-hydroxymethylphenyl) propane, 2,2 -Bis (2,3,4-trihydroxymethylphenyl) propane, 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine and the like can be mentioned, respectively. As the cross-linking agent, one type may be used alone, or two or more types may be used in combination.

When a cross-linking agent is used, the content ratio of the cross-linking agent in the liquid crystal alignment agent is a polymer [A] from the viewpoint of forming a stable liquid crystal alignment film and sufficiently obtaining the effect of enhancing the electrical characteristics of the obtained liquid crystal element. 0.5 parts by mass or more is preferable, and 1 part by mass or more is more preferable with respect to 100 parts by mass of the total amount of. Further, the content ratio of the cross-linking agent is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, based on 100 parts by mass of the total amount of the polymer [A] from the viewpoint of suppressing deterioration of coatability. As the cross-linking agent, one type may be used alone or two or more types may be used in combination.

In addition to the above, examples of other components contained in the liquid crystal alignment agent include antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers and the like. The blending ratio of the other components can be appropriately selected according to each compound as long as the effects of the present disclosure are not impaired.

The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected in consideration of viscosity, volatility, etc., but is preferable. It is in the range of 1 to 10% by mass. When the solid content concentration is 1% by mass or more, the film thickness of the coating film can be sufficiently secured, and a liquid crystal alignment film showing good liquid crystal alignment can be easily obtained. On the other hand, when the solid content concentration is 10% by mass or less, the coating film can be made to have an appropriate thickness, and a liquid crystal alignment film showing good liquid crystal orientation can be easily obtained. In addition, the viscosity of the liquid crystal alignment agent becomes appropriate, and the coatability tends to be good.

≪Liquid crystal alignment film and liquid crystal element≫
The liquid crystal alignment film of the present disclosure is formed by the liquid crystal alignment agent prepared as described above. Further, the liquid crystal element of the present disclosure includes a liquid crystal alignment film formed by 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 for example, TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe). It can be applied to various modes such as Field Switching) type, OCB (Optically Compensated Bend) type, and PSA type (Polymer Sustained Alignment). The liquid crystal element can be manufactured, for example, by a method including 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 each operation mode.

<Step 1: Formation of coating film>
First, a liquid crystal alignment agent is applied onto the substrate, and preferably the coated surface is heated to form a coating film on the substrate. As the base material, for example, glass such as float glass and soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (lipid ring type olefin) can be used. As the transparent conductive film provided on one surface of the base material, a NESA film made of tin oxide (SnO ₂ ) (registered trademark of PPG, USA), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), etc. Can be used. When 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 element, a substrate provided with a comb-shaped patterned electrode and a facing substrate not provided with an electrode are used.

The method of applying the liquid crystal alignment agent to the substrate is not particularly limited, and is, for example, a spin coating method, a printing method (for example, an offset printing method, a flexographic printing method, etc.), an inkjet method, a slit coating method, a bar coater method, and an extension. It can be performed by a die method, a direct gravure coater method, a chamber doctor coater method, an offset gravure coater method, an impregnation coater method, an MB coater method, or the like.

After the liquid crystal alignment agent is applied, preheating is preferably performed for the purpose of preventing the applied liquid crystal alignment agent from dripping. The prebake temperature is preferably 30 to 200 ° C., and the prebake time is preferably 0.25 to 10 minutes. After that, a firing (post-baking) step is carried out for the purpose of completely removing the solvent. The firing temperature (post-baking temperature) at this time is preferably 80 to 280 ° C, more preferably 80 to 250 ° C. The post-bake time is preferably 5 to 200 minutes. The film thickness of the formed film is preferably 0.001 to 1 μm.

<Step 2: Orientation treatment>
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal element, a treatment (alignment treatment) for imparting a liquid crystal alignment ability to the coating film formed in the above step 1 is performed. As a result, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film. As the alignment treatment, it is preferable to use a rubbing treatment in which the surface of the coating film formed on the substrate is rubbed with cotton or the like, or a photoalignment treatment in which the coating film is irradiated with light to impart a liquid crystal alignment ability. On the other hand, in the case of manufacturing a vertically oriented liquid crystal element, the coating film formed in the above step 1 may be used as it is as a liquid crystal alignment film, and the coating film is oriented with respect to further enhance the liquid crystal alignment ability. May be applied.

The light irradiation for photo-alignment includes a method of irradiating the coating film after the post-baking process, a method of irradiating the coating film after the pre-baking process and before the post-baking process, and a pre-baking process and a post-baking process. At least one of them can be used by a method of irradiating the coating film while heating the coating film, or the like. As the radiation to irradiate the coating film, for example, ultraviolet rays including light having a wavelength of 150 to 800 nm and visible light can be used. Preferably, it is ultraviolet light containing light having a wavelength of 200 to 400 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation to be used is linearly polarized light or partially polarized radiation, the irradiation may be performed from a direction perpendicular to the substrate surface, may be performed from an oblique direction, or may be performed in combination thereof. In the case of unpolarized radiation, the irradiation direction is diagonal.

Examples of the light source used 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, an excimer laser and the like. The irradiation amount of radiation is preferably 400 to 50,000 J / m ² , and more preferably 1,000 to 20,000 J / m ² . After irradiation with light to impart orientation ability, the surface of the substrate is washed with, for example, water, an organic solvent (eg, methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.) or a mixture thereof. Or a process of heating the substrate may be performed.

<Step 3: Construction of LCD cell>
A liquid crystal cell is manufactured by preparing two substrates on which a liquid crystal alignment film is formed as described above and arranging the liquid crystal between the two substrates arranged opposite to each other. In order to manufacture a liquid crystal cell, for example, two base materials are arranged facing each other through a gap so that the liquid crystal alignment films face each other, and the peripheral portions of the two base materials are bonded with a sealing agent to form a surface of the base material. A method of injecting and filling a liquid crystal in a cell gap surrounded by a sealant and sealing an injection hole, a method of using an ODF method, and the like can be mentioned. As the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal, and among them, the nematic liquid crystal is preferable.

In the PSA mode, a polymerizable compound (for example, a polyfunctional (meth) acrylate compound) is filled in the cell gap together with the liquid crystal display, and a voltage is applied between the conductive films of the pair of base materials after the liquid crystal cell is constructed. In this state, the liquid crystal cell is irradiated with light. In the production of the liquid crystal element in the PSA mode, the ratio of the polymerizable compound used is 0.01 to 3 parts by mass, preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the total amount of the liquid crystal.

When the liquid crystal element is used as a display device, a polarizing plate is subsequently attached to the outer surface of the liquid crystal cell as needed to form a liquid crystal element. Examples of the polarizing plate include a polarizing plate in which a polarizing film called "H film" in which polyvinyl alcohol is stretched and oriented and iodine is absorbed is sandwiched between a cellulose acetate protective film, or a polarizing plate made of the H film itself.

The liquid crystal element of the present disclosure described in detail above can be effectively applied to various uses. Specifically, for example, various types of clocks, portable game machines, word processors (word processors), notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, LCD TVs, information displays, etc. It can be used as a display device, a dimming device, a retardation film, or the like.

Hereinafter, embodiments will be described in more detail based on the examples, but the present invention is not limitedly interpreted by the following examples.

In the following examples, the weight average molecular weight Mw and the number average molecular weight Mn of the polymer, and the solution viscosity of the polymer solution were measured by the following methods. The required amounts of the raw material compounds and polymers used in the following examples were secured by repeating the synthesis on the synthetic scale shown in the following synthesis examples as necessary.
[Weight average molecular weight Mw and number average molecular weight Mn of polymer]
The weight average molecular weight Mw and the number average molecular weight Mn are polystyrene-equivalent values measured by GPC under the following conditions.
Column: TSKgelGRCXLII manufactured by Tosoh Corporation
Solvent: Tetrahydrofuran (polyorganosiloxane, binder resin)
N, N-dimethylformamide solution containing lithium bromide and phosphoric acid (polyamic acid)
Temperature: 40 ° C
Pressure: 68kgf / cm ²
[Solution viscosity of polymer solution]
The solution viscosity (mPa · s) of the polymer solution was measured at 25 ° C. using an E-type rotational viscometer.

The abbreviations of the compounds are as follows. In the following, the compound represented by the formula (X) may be simply referred to as “compound (X)”.

<Synthesis of polymer>
1. 1. Synthesis of polymer [A] [Synthesis Example 1]
In a 200 mL two-necked flask under nitrogen, 13.3 mmol of compound (MX-2) and 120 mmol of methyl methacrylate (MMA) as a polymerization monomer, and 2,2'-azobis (2,4-dimethylvalero) as a radical polymerization initiator. 2.4 mmol of nitrile and 80 ml of tetrahydrofuran were added as a solvent, and the mixture was polymerized at 70 ° C. for 5 hours. After reprecipitation to n-hexane, the precipitate was filtered and vacuum dried at room temperature for 8 hours to obtain the desired polymer (PA-1). The weight average molecular weight Mw measured by GPC in terms of polystyrene was 45,300, and the molecular weight distribution Mw / Mn was 2.3.

[Synthesis Examples 2 to 7]
Polymers (PA-2) to (PA-7) were obtained by performing the same operations as in Synthesis Example 1 except that the type and amount of the monomers used were changed as shown in Table 1 below.

The numerical values in Table 1 represent the ratio (mol%) of each monomer to the total amount of the monomers used for the synthesis of the polymer. In Table 1, the abbreviations for the monomers represent the following compounds.
MX-1 to MX-4: Compounds represented by the above formulas (MX-1) to (MX-4) MA: GMA methacrylate: Glycydyl methacrylate MMA: Methyl methacrylate PMI: N-phenylmaleimide St. :styrene

2. 2. Synthesis of polyamic acid [Synthesis example 8]
100 mol parts of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CB) as a tetracarboxylic dianhydride, and 4,4'-diaminodiphenylmethane as a diamine (represented by the above formula (DA-1)). A solution containing 80 mol parts of compound) and 20 mol parts of compound (DA-2) dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 60 ° C. for 6 hours to contain 30% by mass of polyamic acid. Got A small amount of the obtained polyamic acid solution was taken, NMP was added, and the solution viscosity measured as a solution having a polyamic acid concentration of 20% by mass was 800 mPa · s. The reaction solution was then poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried under reduced pressure at 40 ° C. for 15 hours to obtain a polymer (PB-1).

[Synthesis Example 9]
100 parts of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (tc-1) was used as the tetracarboxylic dianhydride, and 100 parts of 4,4'-diaminodiphenylmethane (da-1) was used as the diamine. The same operation as in Synthesis Example 8 was carried out except for the above, to obtain a polymer (PB-2).

<Preparation and evaluation of liquid crystal alignment agent>
[Example 1]
1. 1. Preparation of liquid crystal alignment agent 2-Heptanol (B1) and diethylene glycol monoethyl ether (C1) were added to 100 parts by mass of the polymer (PA-1) obtained in the above synthesis example 1, and the solid content concentration was 4.0% by mass. %, The solvent mixture ratio was B1: C1 = 20: 80 (mass ratio). After sufficiently stirring this solution, a liquid crystal alignment agent (S-1) was prepared by filtering with a filter having a pore size of 0.2 μm.

2. 2. Evaluation of Applyability An inkjet device manufactured by Shibaura was filled with a liquid crystal alignment agent (S-1), and inkjet coating was performed on a glass substrate having a contact hole (C / H) and an ITO layer. Contact holes are formed by applying a photosensitive resin on a glass substrate to form a resin layer having a thickness of 3.5 μm, exposing the contact holes through a mask so that the hole diameter is 20 μm and a distance between holes of 200 μm, and then developing the contact holes. Formed. After forming the contact holes, the ITO layer was formed by performing sputtering on the contact hole forming surface of the glass substrate.
After the application of the liquid crystal alignment agent (S-1), prebaking was performed for 1 minute on a hot plate at 80 ° C. Then, the inside of the oven was heated at 200 ° C. for 1 hour in a nitrogen-substituted oven to form a liquid crystal alignment film having a film thickness of 0.1 μm. 200 pieces of this liquid crystal alignment film were visually counted at a magnification of 50 times with a scanning electron microscope (SEM), and among them, the ratio to the whole of the contact holes that could be normally applied without repellency in the contact hole portion (application rate α [ %]) To evaluate the coatability.
α [%] = [(number of contact holes that could be applied normally) / 200] x 100
As the evaluation criteria, the case where the coating rate α was 50% or more was regarded as good, and the case where the coating rate α was less than 50% was regarded as poor. As a result, in this example, α = 72%, and the coatability was good.

3. 3. Manufacture of optical vertical liquid crystal display element On the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film, the above 1. The liquid crystal alignment agent (S-1) prepared in 1 was applied using a spinner and prebaked on a hot plate at 80 ° C. for 1 minute. Then, the inside of the oven was heated at 200 ° C. for 1 hour in a nitrogen-substituted oven to form a coating film having a film thickness of 0.1 μm.
Next, the surface of the coating film is irradiated with 20 J / m ² of polarized ultraviolet rays containing a emission line of 313 nm using an Hg-Xe lamp and a Gran Tailor prism from a direction inclined by 40 ° from the normal of the substrate to impart liquid crystal alignment ability. did. The same operation was repeated to prepare a pair (two sheets) of substrates having an ITO film and a liquid crystal alignment film.
After applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 3.5 μm by screen printing on the outer periphery of the surface of one of the above substrates having a liquid crystal alignment film, the liquid crystal alignment film surfaces of the pair of substrates are opposed to each other. The adhesive was heat-cured at 150 ° C. for 1 hour by pressure-bonding so that the projection directions of the optical axes of the ultraviolet rays of each substrate on the substrate surface were antiparallel. Next, a negative liquid crystal display (MLC-6608, manufactured by Merck) was filled in the gap between the substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to remove the flow orientation at the time of liquid crystal injection, this was heated at 130 ° C. and then slowly cooled to room temperature to manufacture a liquid crystal display element.

4. Evaluation of electrical characteristics 3. Place the liquid crystal display element manufactured in the above in a constant temperature bath, and use the VHR measuring device "VHR-1" manufactured by Toyo Technica to apply a voltage of 1 V at 60 ° C. for an application time of 60 microseconds and a span of 167 milliseconds. After the application, the voltage retention rate (VHR) 1000 milliseconds after the application was released was measured. As the evaluation criteria, the case where the VHR was 80% or more was regarded as good, and the case where the VHR was less than 80% was regarded as poor. As a result, VHR = 81% in this example, and the electrical characteristics were good.

[Examples 2 to 12 and Comparative Examples 1 to 5]
A liquid crystal alignment agent was prepared in the same manner as in Example 1 above, except that the composition of the liquid crystal alignment agent was changed as shown in Table 2 below. Further, using the obtained liquid crystal alignment agent, an optical vertical liquid crystal display element was manufactured in the same manner as in Example 1, and the coatability and electrical characteristics were evaluated. The results are shown in Table 2 below.

[Example 14]
1. 1. Preparation of liquid crystal alignment agent A liquid crystal alignment agent (S-14) was prepared in the same manner as in Example 1 except that the formulation was changed as shown in Table 2 below.
2. 2. Preparation of liquid crystal composition 5% by mass of the liquid crystal compound represented by the following formula (L1-1) and the following formula (L2-1) are expressed with respect to 10 g of nematic liquid crystal (MLC-6608 manufactured by Merck Group). The liquid crystal composition LC1 was obtained by adding 0.3% by mass of the photopolymerizable compound and mixing them.

3. 3. Manufacture of PSA type liquid crystal display element 1. The liquid crystal alignment agent (S-13) prepared in 1) was applied onto the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a spinner, prebaked on a hot plate at 80 ° C. for 1 minute, and then nitrogen. A coating film (liquid crystal alignment film) having a film thickness of 0.08 μm was formed by removing the solvent by heating at 200 ° C. for 1 hour in an oven replaced with. This coating film was subjected to a rubbing treatment using a rubbing machine having a roll wrapped with rayon cloth at a roll rotation speed of 400 rpm, a stage moving speed of 3 cm / sec, and a hair-foot pushing length of 0.1 mm. Then, ultrasonic cleaning was performed in ultrapure water for 1 minute, and then the substrate was dried in a 100 ° C. clean oven for 10 minutes to obtain a substrate having a liquid crystal alignment film. This operation was repeated to obtain a pair (two) of substrates having a liquid crystal alignment film. It should be noted that this rubbing process is a weak rubbing process performed for the purpose of controlling the collapse of the liquid crystal display and performing the orientation division by a simple method.
An epoxy resin adhesive containing aluminum oxide spheres having a diameter of 3.5 μm is applied by screen printing to the outer periphery of the surface of one of the above substrates having a liquid crystal alignment film, and then the liquid crystal alignment film surfaces of the pair of substrates are opposed to each other. The adhesive was heat-cured by stacking and crimping and heating at 150 ° C. for 1 hour. Next, the liquid crystal composition LC1 is filled in the gaps between the substrates from the liquid crystal injection port, the liquid crystal injection port is sealed with an epoxy adhesive, and the liquid crystal display is further sealed at 150 ° C. at 10 ° C. to eliminate the flow orientation during liquid crystal injection. After heating for a minute, it was slowly cooled to room temperature.
Next, an AC 10V having a frequency of 60 Hz was applied between the electrodes to the obtained liquid crystal cell, and in a state where the liquid crystal was driven, 50,000 ultraviolet rays were emitted using an ultraviolet irradiation device using a metal halide lamp as a light source. Irradiation was performed with an irradiation amount of / m ² . It should be noted that this irradiation amount is a value measured using a photometer measured based on a wavelength of 365 nm. As a result, a PSA type liquid crystal display element was manufactured.
4. Evaluation The coatability and electrical characteristics of the liquid crystal alignment agent (S-13) and PSA type liquid crystal display element manufactured above were evaluated in the same manner as in Example 1. The results are shown in Table 3 below.

[Comparative Example 6]
A liquid crystal alignment agent was prepared in the same manner as in Example 1 above, except that the composition of the liquid crystal alignment agent was changed as shown in Table 2 below. Further, using the obtained liquid crystal alignment agent, a PSA type liquid crystal display element was manufactured in the same manner as in Example 13, and the coatability and electrical characteristics were evaluated. The results are shown in Table 2 below.

[Example 14]
1. 1. Preparation of liquid crystal alignment agent A liquid crystal alignment agent (S-14) was prepared in the same manner as in Example 1 except that the formulation was changed as shown in Table 2 below.
2. 2. Manufacture of Optical Horizontal Liquid Crystal Display Element The liquid crystal alignment agent (S-14) prepared above is applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a spinner, and a hot plate at 50 ° C. is applied. Pre-baked for 2 minutes. Then, the inside of the oven was heated at 200 ° C. for 30 minutes in a nitrogen-substituted oven to form a coating film having a film thickness of 0.1 μm. Next, the surface of the coating film is irradiated with 50 J / m ² of polarized ultraviolet rays containing a emission line of 313 nm using an Hg-Xe lamp and a Gran Tailor prism from a direction inclined by 90 ° from the normal of the substrate, and irradiation with polarized ultraviolet rays. After that, heat treatment was performed on a hot plate at 150 ° C. for 10 minutes. By repeating these series of operations, a pair (two sheets) of substrates having a liquid crystal alignment film were produced.
An epoxy resin adhesive containing aluminum oxide spheres having a diameter of 3.5 μm was applied by screen printing to the outer periphery of the surface of one of the above substrates having a liquid crystal alignment film, and then the liquid crystal alignment film surfaces of the pair of substrates were opposed to each other. The adhesive was pressure-bonded so that the projection direction of the optical axis of the ultraviolet rays of each substrate on the substrate surface was horizontal, and the adhesive was thermally cured at 150 ° C. for 1 hour. Next, a positive liquid crystal display (MLC-7028-100, manufactured by Merck) was filled in the gap between the substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to remove the flow orientation at the time of liquid crystal injection, this was heated at 130 ° C. and then slowly cooled to room temperature to manufacture a liquid crystal display element.
3. 3. Evaluation The coatability and electrical characteristics of the liquid crystal alignment agent (S-14) and the optical horizontal liquid crystal display element manufactured above were evaluated in the same manner as in Example 1. The results are shown in Table 2 below.

＜架橋剤＞
Ｄ１：Ｎ，Ｎ，Ｎ’，Ｎ’－テトラキス（２－ヒドロキシエチル）ヘキサンジアミド In Table 2, in Examples 10 to 14 and Comparative Examples 5 and 6, two kinds of polymers were used as polymer components. Of these, in Examples 10 to 14, A1: A2 = 10: 90 (parts by mass) was blended. In Comparative Example 5, A1: the other polymer was blended at a ratio of 90:10 (parts by mass), and in Comparative Example 6, A2: another polymer was blended at a ratio of 90:10 (parts by mass).
The numerical value in the column of the solvent component represents the compounding ratio (part by mass) of each compound with respect to 100 parts by mass of the total amount of the solvent component used for preparing the liquid crystal alignment agent.
In Example 11, 10 parts by mass of the cross-linking agent was added to 100 parts by mass of the total amount of the polymer components.
The abbreviations of the compounds are as follows.
<Solvent>
B1: 2-Heptanol B2: 1-Dodecanol B3: 1-Tetradecanol C1: Diethylene glycol monoethyl ether C2: Dipropylene glycol monomethyl ether DIBC: Diisobutylcarbinol 2BuOH: 2-Butanol NMP: N-methyl-2-pyrrolidone BC : Ethylene glycol monobutyl ether

<Crosslinking agent>
D1: N, N, N', N'-Tetrakis (2-hydroxyethyl) hexanediamide

As is clear from Table 2, the liquid crystal alignment agents of Examples 1 to 14 showed good coatability with less repellency in the contact hole portion even when applied to the substrate on which the contact hole was formed. Further, in Examples 1 to 14, the voltage holding ratio of the liquid crystal display element was high, and the electrical characteristics were good. In particular, the liquid crystal alignment agents of Examples 7, 8, 10 to 14 showed a high coating rate α of 80% or more, and were excellent in coatability. Further, when comparing Example 8 and Example 9, the liquid crystal alignment agent of Example 8 further containing compound [C] becomes the liquid crystal alignment agent of Example 9 containing NMP instead of compound [C]. In comparison, the coatability was good.
On the other hand, the liquid crystal alignment agents of Comparative Examples 1 to 4 containing no compound [B] had a low coating rate α of about 22 to 45%, and the coating property was not sufficient. Further, the liquid crystal alignment agent of Comparative Example 5 containing the compound [B] but having a high content of polyamic acid had a coating rate α of 11%, which was even lower than that of Comparative Examples 1 to 4. In Comparative Example 6 containing NMP, the coating rate α showed an even lower value of 7%.

From the above results, it was clarified that the liquid crystal alignment agent containing the polymer [A] as the main component of the polymer component and containing the compound [B] has excellent coatability to the substrate.

Claims (11)

The amount of the polymer [A] containing a structural unit derived from a monomer having a polymerizable carbon-carbon unsaturated bond is 50% by mass or more based on the total amount of the polymer components.
Compound [B] represented by the following formula (1) and
A liquid crystal alignment agent containing.
R ¹ -OH ... (1)
(In the formula (1), R ¹ is a linear alkyl group having 5 or more carbon atoms.) The liquid crystal orientation according to claim 1, wherein the polymer [A] contains a polymer having at least one specific structure selected from the group consisting of a photo-oriented group, a liquid crystal oriented group and a liquid crystal side chain. Agent. The liquid crystal alignment agent according to claim 2, wherein the polymer [A] contains a polymer having the specific structure and a polymer having no specific structure. The liquid crystal alignment agent according to any one of claims 1 to 3, wherein the polymer [A] contains a polymer having a crosslinkable group. The polymer [A] has a ring structure of at least one of an oxetane ring and an oxylan ring and a functional group that reacts with at least one of the oxetane ring and the oxylan ring by heating in the same polymer or a different polymer. The liquid crystal alignment agent according to any one of claims 1 to 4, which comprises. The liquid crystal alignment agent according to any one of claims 1 to 5, wherein the content ratio of the compound [B] is 1 to 95% by mass with respect to the total amount of the solvent component contained in the liquid crystal alignment agent. At least selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), a compound represented by the following formula (4), and a cyclic ketone having 4 to 7 carbon atoms. The liquid crystal alignment agent according to any one of claims 1 to 6, further comprising one compound [C].
R ^2- (OR ³ ) _n -OR ⁴ ... (2)
(In the formula (2), R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ³ is an alkanediyl group having 2 to 4 carbon atoms. R ⁴ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. It is an alkyl group of 1 to 4. n is an integer of 0 to 3. When n is 2 or ³ , a plurality of R3s in the formula are the same group or different groups from each other. N is 0. In this case, R ² is an alkyl group having 3 to 5 carbon atoms, and R ⁴ is a hydrogen atom.)

(In the formula (3), R ⁵ is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or an alkoxyalkyl group having 2 or 3 carbon atoms. X ¹ is a single bond or oxygen. It is an atom. R ⁶ is an alkylandyl group having 1 to 3 carbon atoms. R ⁷ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. M is 0 or 1.
In the formula (4), R ⁸ and R ⁹ are independently an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or an alkoxyalkyl group having 2 or 3 carbon atoms. X ² is a single bond or an alkanediyl group having 1 or 2 carbon atoms. ) The liquid crystal alignment agent according to claim 7, wherein the content ratio of the compound [C] is 5 to 95% by mass with respect to the total amount of the solvent component contained in the liquid crystal alignment agent. The liquid crystal alignment agent according to any one of claims 1 to 8, further comprising a cross-linking agent. A liquid crystal alignment film formed by using the liquid crystal alignment agent according to any one of claims 1 to 9. A liquid crystal element comprising the liquid crystal alignment film according to claim 10.