JP7421159B2 - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Description

The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film obtained from the liquid crystal aligning agent, and a liquid crystal display element having the liquid crystal aligning film.

Currently, liquid crystal display elements are widely used in image display portions of many devices such as digital cameras, personal computers, portable terminals, and televisions. Such a liquid crystal display element has a structure in which a fluid liquid crystal composition is sandwiched and sealed between two support substrates, and the surface of the substrates in contact with the liquid crystal has a liquid crystal alignment layer for aligning liquid crystal molecules. A membrane is provided. A liquid crystal aligning film is generally produced through a process of applying a liquid crystal aligning agent onto the substrate. Moreover, when aligning liquid crystal molecules in the in-plane direction of the substrate, rubbing treatment, photo-alignment treatment, etc. are performed on the coating film obtained from the liquid crystal aligning agent.

There are various characteristics required for a liquid crystal alignment film. Resistance to rubbing treatment (rubbing resistance) is one of the important characteristics. Rubbing treatment is known as a method of forming a liquid crystal alignment film from a polymer film formed on a substrate in the manufacturing process of a liquid crystal display element, and is still widely used industrially.

It is known that this rubbing process has a problem in that dust and scratches generated by scraping the liquid crystal alignment film deteriorate the display quality of the display element. Therefore, the liquid crystal alignment film is required to have high rubbing resistance with less dust and damage to the liquid crystal alignment film caused by the rubbing treatment. For example, Patent Documents 1 and 2 disclose liquid crystal aligning agents aimed at providing a liquid crystal aligning film in which the coating film is less likely to be scraped or damaged by rubbing treatment. Furthermore, Patent Document 3 describes a liquid crystal alignment agent that aims to provide a highly reliable liquid crystal alignment film with low ion density and high voltage retention of liquid crystal display elements even at high temperatures, in addition to the rubbing resistance of the liquid crystal alignment film. Disclosed.

Japanese Patent Application Publication No. 2008-203332 International Publication Publication 2010/053128 International Publication Publication 2010/050523

BACKGROUND OF THE INVENTION As liquid crystal display elements have become increasingly sophisticated in recent years, liquid crystal alignment films are required to exhibit various properties at higher levels than ever before. For example, as the definition of liquid crystal display elements has become higher, there has been a need for liquid crystal alignment films that have less scratching and damage to the coating film than before in terms of rubbing resistance. In light of the above, an object of the present invention is to provide a liquid crystal aligning film and a liquid crystal aligning agent that have excellent rubbing resistance.

（Ｒ^１は水素又は一価の有機基を表し、ｎは０～２の整数であり、＊は他の基に結合する部位を表す。）
（２）前記式（１）で表される環状アセタール基を有する重合体が、後述する式（２）で表されるジアミンに由来する重合体である、上記（１）に記載の液晶配向剤。 The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems, and the present invention has the following aspects.
(1) A liquid crystal aligning agent characterized by containing a polymer having a cyclic acetal group represented by the following formula (1).

(R ¹ represents hydrogen or a monovalent organic group, n is an integer from 0 to 2, and * represents a site bonded to another group.)
(2) The liquid crystal aligning agent according to (1) above, wherein the polymer having a cyclic acetal group represented by the formula (1) is a polymer derived from a diamine represented by the formula (2) described below. .

（Ｘ^１はテトラカルボン酸誘導体に由来する４価の有機基を表す。Ｙ^１は式（１）の構造を含むジアミンに由来する２価の有機基を表す。Ｒ^２は水素原子又は炭素数１～５のアルキル基を表す。） (3) The above polymer having a cyclic acetal group is at least one selected from the group consisting of a polyimide precursor containing a structural unit represented by the following formula (3) and a polyimide that is an imidized product thereof. The liquid crystal aligning agent according to (1).

(X ¹ represents a tetravalent organic group derived from a tetracarboxylic acid derivative. Y ¹ represents a divalent organic group derived from a diamine containing the structure of formula (1). R ² represents a hydrogen atom or the number of carbon atoms. Represents an alkyl group of 1 to 5.)

(4) The liquid crystal aligning agent according to the above (3), wherein in the formula (3), the structure of X ¹ is at least one selected from the following structures.

（５）前記式（３）で表される構造単位が、前記重合体の全構造単位に対して１０モル％以上である、請求項４又は５に記載の液晶配向剤。
（６）上記（１）～（５）のいずれか１項に記載の液晶配向剤から得られる液晶配向膜。
（７）上記（６）に記載の液晶配向膜を具備する液晶表示素子。

(5) The liquid crystal aligning agent according to claim 4 or 5, wherein the structural unit represented by the formula (3) is 10 mol% or more with respect to the total structural units of the polymer.
(6) A liquid crystal aligning film obtained from the liquid crystal aligning agent according to any one of (1) to (5) above.
(7) A liquid crystal display element comprising the liquid crystal alignment film according to (6) above.

（各記号の定義は、後記する通りである。）
（９）上記（８）に記載のジアミンを由来とする環状アセタール基を有する重合体。 (8) A diamine having a cyclic acetal group represented by the following formula (2).

(The definition of each symbol is as shown below.)
(9) A polymer having a cyclic acetal group derived from the diamine described in (8) above.

（各記号の定義は、上記（４）における記載と同じである。） (10) The polymer according to (9) above, wherein the polymer having a cyclic acetal group is a polyimide precursor containing a structural unit represented by the following formula (3), and a polyimide that is an imidized product thereof.

(The definition of each symbol is the same as described in (4) above.)

(11) The polymer according to (10) above, wherein in the formula (3), the structure of X ¹ is at least one selected from the following structures.

（１２）前記式（３）で表される構造単位が、前記重合体の全構造単位に対して１０モル％以上である、上記（１０）又は（１１）に記載の重合体。

(12) The polymer according to (10) or (11) above, wherein the structural unit represented by the formula (3) is 10 mol% or more based on the total structural units of the polymer.

The liquid crystal aligning film obtained from the liquid crystal aligning agent of the present invention has excellent rubbing resistance, and a liquid crystal display element comprising the liquid crystal aligning film can provide a high-performance liquid crystal display element.

In the present invention, the mechanism by which a liquid crystal aligning film with excellent rubbing resistance is obtained by using a liquid crystal aligning agent containing a polymer having a cyclic acetal group represented by the above formula (1) is not necessarily clear. , it can be considered as follows.

Cyclic acetals act as protecting groups for aldehydes. The cyclic acetal moiety decomposes into aldehyde and diol when the alignment film is heated and baked. It is thought that the generated aldehyde condenses with the amine site in the liquid crystal aligning agent and forms a bond between the polymers. It is thought that due to this bond formation, a liquid crystal alignment film with excellent rubbing resistance can be obtained.

上記式（１）において、Ｒ^１は水素又は一価の有機基を表し、ｎは０～２の整数であり、＊は他の基に結合する部位を表す。本発明における特定重合体は、上記式（１）の構造を有するジアミンから得られる重合体であるのが好ましい。 The liquid crystal aligning agent of the present invention is a liquid crystal aligning agent containing a polymer (hereinafter also referred to as a specific polymer) having a structure represented by the following formula (1).
<Specific structure>

In the above formula (1), R ¹ represents hydrogen or a monovalent organic group, n is an integer of 0 to 2, and * represents a site bonded to another group. The specific polymer in the present invention is preferably a polymer obtained from a diamine having the structure of formula (1) above.

上記式（２）中、Ｒ^１およびｎの定義は、上記式（１）と同様である。Ａｒはフェニレン、ナフチレン、ビフェニレンから選ばれる芳香族炭化水素基を示し、それらには有機基が置換していても良く、水素原子はハロゲン原子に置き換わっていても良い。Ｔ^１、Ｔ^２はそれぞれ独立して、単結合又は－Ｏ－、－ＣＯＯ－、－ＯＣＯ－、－ＮＨＣＯ－、－ＣＯＮＨ－、－ＮＨ－、－ＣＨ_２Ｏ－、－Ｎ（ＣＨ_３）－、－ＣＯＮ（ＣＨ_３）－、－Ｎ（ＣＨ_３）ＣＯ－の結合基であり、Ｗは単結合もしくは非置換もしくはフッ素原子によって置換されている炭素原子数１～２０のアルキレン基（ただしアルキレン基の-ＣＨ_２-または-ＣＦ_２-は-ＣＨ＝ＣＨ-で任意に置き換えられていてもよく、次に挙げるいずれかの基が互いに隣り合わない場合において、これらの基に置き換えられていてもよい；－Ｏ－、－ＣＯＯ－、－ＯＣＯ－、－ＮＨＣＯ－、－ＣＯＮＨ－、－ＮＨ－、二価の炭素環、二価の複素環。）である。 <Specific diamine>
Examples of diamines having a cyclic acetal group represented by the above formula (1) (hereinafter also referred to as specific diamines) include diamines represented by the following formula (2).

In the above formula (2), the definitions of R ¹ and n are the same as in the above formula (1). Ar represents an aromatic hydrocarbon group selected from phenylene, naphthylene, and biphenylene, which may be substituted with an organic group, and the hydrogen atom may be replaced with a halogen atom. T ¹ and T ² are each independently a single bond or -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N(CH ₃ ) -, -CON(CH ₃ )-, -N(CH ₃ )CO- are bonding groups, and W is a single bond or an alkylene group having 1 to 20 carbon atoms that is unsubstituted or substituted with a fluorine atom (however, -CH ₂ - or -CF ₂ - of the alkylene group may be optionally substituted with -CH=CH-, and in cases where any of the following groups are not adjacent to each other, these groups are substituted. -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, divalent carbocycle, divalent heterocycle).

上記式中、Ｒ^１の定義は、上記式（１）におけるものと同じであり、特に、水素原子、メチル基（Ｍｅ）又はエチル基（Ｅｔ）が好ましい。Ｒ^３は水素、又は一価の有機基を表し、特に、水素原子、Ｍｅ基又はＥｔ基が好ましい。ｎの定義は、上記式（１）におけるものと同じであり、特に、０又は１が好ましい。ｍは１～２０の整数を表す。 Specific examples of the diamine of the above formula (2) include the following.

In the above formula, the definition of R ¹ is the same as that in the above formula (1), and a hydrogen atom, a methyl group (Me), or an ethyl group (Et) is particularly preferred. R ³ represents hydrogen or a monovalent organic group, and particularly preferably a hydrogen atom, Me group or Et group. The definition of n is the same as in the above formula (1), and particularly preferably 0 or 1. m represents an integer from 1 to 20.

上記式（４）中、Ｒ^１、ｎ、Ａｒ、Ｔ^１、Ｔ^２及びＷの定義は上記式（２）におけるものと同じである。 <Method for synthesizing specific diamine>
Examples of the method for synthesizing the specific diamine in the present invention include a method of synthesizing a dinitro compound represented by the following formula (4), and further reducing the nitro group to convert it into an amino group.

In the above formula (4), the definitions of R ¹ , n, Ar, T ¹ , T ² and W are the same as in the above formula (2).

The catalyst used in the reduction reaction of the nitro group is preferably a commercially available metal supported on activated carbon, such as palladium-activated carbon, platinum-activated carbon, rhodium-activated carbon, and the like. Furthermore, the catalyst does not necessarily have to be an activated carbon-supported metal catalyst such as palladium hydroxide, platinum oxide, or Raney nickel. Among these, palladium-activated carbon is preferred.

In order to make the reduction reaction proceed more effectively, the reaction may be carried out in the presence of activated carbon. At this time, the amount of activated carbon used is preferably 1 to 30% by mass, more preferably 10 to 20% by mass, based on the dinitro compound. For similar reasons, the reaction may also be carried out under pressure. In this case, in order to avoid reduction of benzene nuclei, the reaction is preferably carried out at a pressure of 20 atm or less, more preferably up to 10 atm.

The solvent in the above reduction reaction can be used without any restriction as long as it does not react with each raw material. For example, aprotic polar organic solvents (DMF, DMSO, DMAc, NMP, etc.); ethers (Et ₂ O, i-Pr ₂ O, TBME, CPME, THF, dioxane, etc.); aliphatic hydrocarbons (pentane, Hexane, heptane, petroleum ether, etc.); Aromatic hydrocarbons (benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, nitrobenzene, tetralin, etc.); Halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane) etc.); lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.); nitriles (acetonitrile, propionitrile, butyronitrile, etc.); and the like can be used. These solvents can be appropriately selected in consideration of the ease with which the reaction occurs, and two or more of them can be used as a mixture. If necessary, the solvent can be dried using an appropriate dehydrating agent or drying agent and used as a non-aqueous solvent. The amount of the solvent used (reaction concentration) is 0.1 to 100 times the weight of the dinitro compound, preferably 0.5 to 30 times the weight, and more preferably 1 to 10 times the weight.

The reaction temperature ranges from -100°C to the boiling point of the solvent used, preferably -50 to 150°C. The reaction time is usually 0.05 to 350 hours, preferably 0.5 to 100 hours.

[Production method of formula (4)]
There is no particular restriction on the method of synthesizing formula (4). For example, as shown in the reaction formula below based on the literature (L. Fan et al., Organic & Biomolecular Chemistry, 17, 5121 (2019)), by reacting an aldehyde compound and a diol compound in the presence of an acid, the formula (4) can be obtained.

Examples of acid catalysts used to protect the aldehyde group include hydrogen chloride (or hydrochloric acid), sulfuric acid, p-toluenesulfonic acid, phosphoric acid, trimethylsilyl triflate, 1,3,5-benzenetricarboxylic acid, tungstophosphoric acid, tungstosilicic acid, etc. can be mentioned. Among these, p-toluenesulfonic acid is preferred.
The solvent in the above reaction can be used without any restriction as long as it does not react with each raw material. For example, ethers (Et ₂ O, i-Pr ₂ O, TBME, CPME, THF, dioxane, etc.); aliphatic hydrocarbons (pentane, hexane, heptane, petroleum ether, cyclohexane, etc.); aromatic hydrocarbons (Benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, nitrobenzene, tetralin, etc.); Halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.); Nitriles (acetonitrile, propionitrile, butyronitrile, etc.) ; etc. can be used. Among these, toluene and cyclohexane are preferred. These solvents can be appropriately selected in consideration of the ease with which the reaction occurs, and two or more of them can be used as a mixture. If necessary, the solvent can be dried using an appropriate dehydrating agent or drying agent and used as a non-aqueous solvent. The amount of the solvent used (reaction concentration) is 0.1 to 100 times the amount of the aldehyde compound, preferably 0.5 to 30 times, and more preferably 1 to 10 times the amount by weight.
The reaction temperature ranges from -100°C to the boiling point of the solvent used, preferably -50 to 150°C. The reaction time is usually 0.05 to 350 hours, preferably 0.5 to 100 hours.

上記式（３）中、Ｘ^１はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ^１は式（１）の構造を含むジアミンに由来する２価の有機基であり、Ｒ^２は水素原子又は炭素数１～５のアルキル基である。Ｒ^２は、加熱によるイミド化のしやすさの点から、水素原子、メチル基又はエチル基が好ましい。 <Polymer>
The polymer having a cyclic acetal group of the present invention has a structure represented by the above formula (1). Specific examples include polyamic acid, polyamic acid ester, polyimide, polyurea, polyamide, and the like. From the viewpoint of a liquid crystal aligning agent, at least one kind selected from a polyimide precursor containing a structural unit represented by the following formula (3) and a polyimide that is an imidized product thereof is more preferable.

In the above formula (3), X ¹ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ¹ is a divalent organic group derived from a diamine containing the structure of formula (1), and R ² is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ² is preferably a hydrogen atom, a methyl group, or an ethyl group from the viewpoint of ease of imidization by heating.

<Tetracarboxylic dianhydride>
X ¹ in the polyimide precursor of the above formula (3) is determined by the solubility of the polymer in a solvent, the applicability of a liquid crystal alignment agent, the alignment of liquid crystal when used as a liquid crystal alignment film, voltage holding rate, accumulated charge, etc. are appropriately selected depending on the degree of required properties, and may be one type or two or more types mixed in the same polymer.

Specific examples of X ¹ include structures of formulas (X-1) to (X-46) listed in sections 13 to 14 of International Publication No. 2015/119168.
Preferred structures of X ¹ are shown below.

Among the above, (A-1) and (A-2) are particularly preferred from the viewpoint of further improving the rubbing resistance, and (A-4) is particularly preferred from the viewpoint of further improving the relaxation rate of accumulated charges. A-15) to (A-17) are particularly preferred from the viewpoint of further improving the liquid crystal orientation and the relaxation rate of accumulated charges.
Further, among the above, (A-1), (A-4), (A-5), and (A-7) are preferable from the viewpoint of further improving the voltage holding ratio.

<Diamine>
In the above formula (3), a specific example of Y ¹ is a structure obtained by removing two amino groups from the diamine of the above formula (2).

式（５）において、Ｘ^２はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ^２は式（１）の構造を含まないジアミンに由来する２価の有機基であり、Ｒ^２は、前記式（３）の定義と同じであり、Ｒ^４は水素原子又は炭素数１～４のアルキル基を表す。また、２つあるＲ^２の少なくとも一方は水素原子であることが好ましい。 <Polymer (other structural units)>
The polyimide precursor containing the structural unit represented by the formula (3) may contain the structural unit represented by the following formula (5) within a range that does not impair the effects of the present invention.

In formula (5), X ² is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ² is a divalent organic group derived from a diamine that does not contain the structure of formula (1), and R ² is the same as the definition of formula (3) above, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Moreover, it is preferable that at least one of the two ^R2 's is a hydrogen atom.

Specific examples of X ² include the same structures as those exemplified for X ¹ in formula (3), including preferred examples. Further, ^Y2 in the polyimide precursor is a divalent organic group derived from a diamine that does not include the structure of formula (1), and its structure is not particularly limited. In addition, ^Y2 is determined depending on the degree of required properties, such as the solubility of the polymer in a solvent, the applicability of the liquid crystal alignment agent, the alignment of the liquid crystal when used as a liquid crystal alignment film, the voltage holding rate, and the accumulated charge. They are selected as appropriate, and two or more types may be mixed in the same polymer.

To give specific examples of Y ² , the structure of formula (2) published in section 4 of International Publication No. 2015/119168, and the structure of formula (Y-1) to ( Structures of Y-97), (Y-101) to (Y-118); divalent organic group obtained by removing two amino groups from formula (2), published in Section 6 of International Publication No. 2013/008906 ; A divalent organic group obtained by removing two amino groups from the formula (1) published in section 8 of International Publication No. 2015/122413; A divalent organic group of formula (3) published in section 8 of International Publication No. 2015/060360 Structure: Divalent organic group obtained by removing two amino groups from formula (1) described in section 8 of Japanese Patent Publication No. 2012-173514; Formula (A ) to (F) with two amino groups removed, and the like.

<Other diamines>
In addition to the above diamine components, the following diamine components can be used as other diamines.
<Other diamine: diamine having the structure of formula (0)>
Other diamines have the structure of the following formula (0).

In the above formula (0), A ¹ and A ⁵ each independently represent a single bond or an alkylene group having 1 to 5 carbon atoms. A single bond or a methylene group is preferable from the viewpoint of reactivity with a functional group in a sealing material used to bond the upper and lower substrates together.

In the above formula (0), A ² and A ⁴ each independently represent an alkylene group having 1 to 5 carbon atoms, preferably a methylene group or an ethylene group. A ³ represents an alkylene group or a cycloalkylene group having 1 to 6 carbon atoms, and is preferably a methylene group or an ethylene group from the viewpoint of reactivity with the functional group in the sealing material.

In the above formula (0), B ¹ and B ² are each independently a single bond, -O-, -NH-, -N(CH ₃ )-, -CO-, -COO-, -OCO-, Represents -CONH-, -NHCO-, -CON(CH ₃ )- or -N(CH ₃ )CO. From the viewpoint of orientation of the obtained liquid crystal alignment film, a single bond or -O- is preferable.

In the above formula (0), D ₁ represents a protective group that replaces a hydrogen atom by heat. D ₁ functions as a protecting group for an amino group, and is a functional group that is replaced by a hydrogen atom by heat. From the viewpoint of storage stability of the liquid crystal aligning agent, D ₁ is preferably a protecting group that does not desorb at room temperature, more preferably a protecting group that desorbs at a temperature of 80°C or higher, and a protecting group that desorbs at a temperature of 100°C or higher, particularly 120°C or higher. More preferred are protecting groups that release. The desorption temperature is preferably 250°C or lower, more preferably 230°C or lower. Desorption temperatures that are too high can lead to polymer decomposition. Examples of such D ₁ include tert-butoxycarbonyl (t-Boc) group, 9-fluorenylmethoxycarbonyl group, and the like. Among these, t-Boc group is preferred from the viewpoint of temperature-dependent elimination.

In the above formula (0), a is 0 or 1. A ² and A ³ (when a is 1), A ³ and A ⁴ (when a is 1), or A ² and A ⁴ (when a is 0) do not bond to each other. That is, when a is 1, A ² and A ³ , A ³ and A ⁴ do not form a ring, and the N atom bonded to D ₁ does not constitute a part of the ring. Similarly, when a is 0, A ² and A ⁴ do not form a ring, and the N atom bonded to D ₁ does not form part of the ring.

上記式（０’）及び上記式（０’’）中、Ａ^１～Ａ^５、Ｂ^１、Ｂ^２、Ｄ_１、ａ並びに＊は、上記式（０）の場合と同様である。 In the above formula (0), * represents a site that is bonded to another group. Viewed from *, the bonding position of A ¹ and/or A ⁵ to the benzene ring may be any of the ortho position, meta position, and para position, but the para position is preferable from the viewpoint of liquid crystal orientation of the liquid crystal alignment film. That is, the above formula (0) is preferably the following formula (0') or the following formula (0'').

In the above formula (0') and the above formula (0''), A ¹ to A ⁵ , B ¹ , B ² , D ₁ , a, and * are the same as in the above formula (0).

Specific examples of such specific diamines include diamines represented by the following formulas (0-1) to (0-21).

<Other diamines: diamines with specific side chain structures that exhibit vertical alignment>
When used as a liquid crystal alignment agent in a VA type liquid crystal display element, it is preferable to prepare a specific polymer using a diamine having a specific side chain structure that exhibits vertical alignment ability. This diamine having a specific side chain structure has at least one type of side chain structure selected from the group represented by the following formulas [S1] to [S3]. Below, diamines represented by formulas [S1] to [S3], which are examples of diamines having such specific side chain structures, will be explained in order.

上記式［Ｓ１］中、Ｘ^１及びＸ^２は、それぞれ独立して、単結合、－（ＣＨ_２）_ａ－（ａは１～１５の整数である）、－ＣＯＮＨ－、－ＮＨＣＯ－、－ＣＯＮ（ＣＨ_３）－、－ＮＨ－、－Ｏ－、－ＣＯＯ－、－ＯＣＯ－又は－（（ＣＨ_２）_ａ１－Ａ_１）_ｍ１－を表す。このうち、複数のａ１はそれぞれ独立して１～１５の整数であり、複数のＡ_１はそれぞれ独立して酸素原子又は－ＣＯＯ－を表し、ｍ１は１～２である。 [A]: Diamine having a specific side chain structure represented by the following formula [S1]

In the above formula [S1], X ¹ and X ² each independently represent a single bond, -(CH ₂ ) _a - (a is an integer from 1 to 15), -CONH-, -NHCO-, - CON(CH ₃ )-, -NH-, -O-, -COO-, -OCO-, or -((CH ₂ ) _a1 -A ₁ ) _m1 -. Among these, the plurality of a1's are each independently an integer of 1 to 15, the plurality of _A1 's each independently represents an oxygen atom or -COO-, and m1 is 1 to 2.

Among them, from the viewpoint of availability of raw materials and ease of synthesis, X ¹ and X ² are each independently a single bond, -(CH ₂ ) _a - (a is an integer from 1 to 15), -O-, -CH ₂ O- or -COO- is preferred, and a single bond, -(CH ₂ ) _a - (a is an integer from 1 to 10), -O-, -CH ₂ O- or -COO - is more preferable.

In the above formula [S1], G ¹ and G ² are each independently a divalent aromatic group having 6 to 12 carbon atoms or a divalent alicyclic group having 3 to 8 carbon atoms. represents a cyclic group. Any hydrogen atom on the cyclic group can be an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, or a fluorine-containing alkoxy group having 1 to 3 carbon atoms. Alternatively, it may be substituted with a fluorine atom. m and n are each independently an integer of 0 to 3, and the total of m and n is 1 to 4.

In the above formula [S1], R ¹ represents alkyl having 1 to 20 carbon atoms, alkoxy having 1 to 20 carbon atoms, or alkoxyalkyl having 2 to 20 carbon atoms. Any hydrogen forming R ¹ may be substituted with fluorine. Among these, examples of divalent aromatic groups having 6 to 12 carbon atoms include phenylene, biphenylene, naphthalene, and the like. Furthermore, examples of the divalent alicyclic group having 3 to 8 carbon atoms include cyclopropylene, cyclohexylene, and the like.

Preferred specific examples of the above formula [S1] include the following formulas [S1-x1] to [S1-x7].

In the above formulas [S1-x1] to [S1-x7], R ¹ is the same as in the above formula [S1]. X ^p is -(CH ₂ ) _a - (a is an integer from 1 to 15), -CONH-, -NHCO-, -CON(CH ₃ )-, -NH-, -O-, -CH ₂ Represents O-, -COO- or -OCO-. A ₁ represents an oxygen atom or -COO-* (the bond marked with "*" is bonded to (CH ₂ ) _a2 ). A ₂ represents an oxygen atom or *-COO- (the bond marked with "*" is bonded to (CH ₂ ) _a2 ). a ₁ is an integer of 0 or 1, and a ₂ is an integer of 2 to 10. Cy represents a 1,4-cyclohexylene group or a 1,4-phenylene group.

上記式［Ｓ２］中、Ｘ^３は単結合、－ＣＯＮＨ－、－ＮＨＣＯ－、－ＣＯＮ（ＣＨ_３）－、－ＮＨ－、－Ｏ－、－ＣＨ_２Ｏ－、－ＣＯＯ－又は－ＯＣＯ－を表す。なかでも、液晶配向剤の液晶配向性の点から、Ｘ^３は－ＣＯＮＨ－、－ＮＨＣＯ－、－Ｏ－、－ＣＨ_２Ｏ－、－ＣＯＯ－又は－ＯＣＯ－が好ましい。 [B]: Diamine having a specific side chain structure represented by the following formula [S2]

In the above formula [S2], X ³ is a single bond, -CONH-, -NHCO-, -CON(CH ₃ )-, -NH-, -O-, -CH ₂ O-, -COO- or -OCO- represents. Among these, from the viewpoint of liquid crystal alignment of the liquid crystal aligning agent, -CONH-, -NHCO-, -O-, -CH ₂ O-, -COO- or -OCO- is preferable for X ³ .

In the above formula [S2], R ² represents alkyl having 1 to 20 carbon atoms or alkoxyalkyl having 2 to 20 carbon atoms. Any hydrogen forming R ² may be substituted with fluorine. Among these, R ² is preferably alkyl having 3 to 20 carbon atoms or alkoxyalkyl having 2 to 20 carbon atoms from the viewpoint of liquid crystal alignment of the liquid crystal aligning agent.

上記式［Ｓ３］中、Ｘ^４は－ＣＯＮＨ－、－ＮＨＣＯ－、－Ｏ－、－ＣＯＯ－又は－ＯＣＯ－を表す。Ｒ^３はステロイド骨格を有する構造を表す。ここでのステロイド骨格は、３つの六員環及び１つの五員環が結合した下記式（ｓｔ）で表される骨格を有する。

[C]: Diamine having a specific side chain structure represented by the following formula [S3]

In the above formula [S3], X ⁴ represents -CONH-, -NHCO-, -O-, -COO- or -OCO-. R ³ represents a structure having a steroid skeleton. The steroid skeleton here has a skeleton represented by the following formula (st) in which three six-membered rings and one five-membered ring are bonded.

上記式［Ｓ３－ｘ］中、Ｘは、上記式［Ｘ１］又は［Ｘ２］を表す。また、Ｃｏｌは、上記式［Ｃｏｌ１］～［Ｃｏｌ４］からなる群から選ばれる少なくとも１種を表し、Ｇは、上記式［Ｇ１］又は［Ｇ２］を表す。＊は他の基に結合する部位を表す。 An example of the above formula [S3] is the following formula [S3-x].

In the above formula [S3-x], X represents the above formula [X1] or [X2]. Further, Col represents at least one type selected from the group consisting of the above formulas [Col1] to [Col4], and G represents the above formula [G1] or [G2]. * represents a site that binds to another group.

Examples of preferable combinations of X, Col and G in the above formula [S3-x] include the following combinations. That is, [X1] and [Col1] and [G1], [X1] and [Col1] and [G2], [X1] and [Col2] and [G1], [X1] and [Col2] and [G2], [X1] and [Col3] and [G2], [X1] and [Col4] and [G2], [X1] and [Col3] and [G1], [X1] and [Col4] and [G1], [X2 ] and [Col1] and [G2], [X2] and [Col2] and [G2], [X2] and [Col2] and [G1], [X2] and [Col3] and [G2], [X2] and [Col4] and [G2], [X2], [Col1] and [G1], [X2], [Col4] and [G1].

Specific examples of the above formula [S3] include the structure obtained by removing the hydroxyl group from the steroid compound described in paragraph [0024] of Japanese Patent Application Publication No. 4-281427, and the structure described in paragraph [0030] of the same publication. A structure obtained by removing an acid chloride group from a steroid compound, a structure obtained by removing an amino group from a steroid compound described in paragraph [0038] of the same publication, a structure obtained by removing a halogen group from a steroid compound described in paragraph [0042] of the same publication, and Examples include the structures described in paragraphs [0018] to [0022] of Japanese Patent Application Laid-Open No. 8-146421.

A typical example of a steroid skeleton is cholesterol (a combination of [Col1] and [G2] in the above formula [S3-x]), but a steroid skeleton that does not contain cholesterol can also be used. That is, examples of diamines having a steroid skeleton include cholestanyl 3,5-diaminobenzoate, but it is also possible to use a diamine component that does not contain such diamines having a cholesterol skeleton. Moreover, as a diamine having a specific side chain structure, one that does not contain an amide at the linking position between the diamine and the side chain can also be used. Even if such a diamine is used, in this embodiment, even if a diamine component that does not include a diamine having a cholesterol skeleton is used, a liquid crystal alignment film and a liquid crystal display element that can ensure a high voltage holding rate over a long period of time can be produced. It is possible to provide a liquid crystal aligning agent that can obtain the following.

上記式［１－Ｓ１］中、Ｘ^１、Ｘ^２、Ｇ^１、Ｇ^２、Ｒ^１、ｍ及びｎは、上記式［Ｓ１］における場合と同様である。上記式［１－Ｓ２］中、Ｘ^３及びＲ^２は、上記式［Ｓ２］における場合と同様である。上記式［１－Ｓ３］中、Ｘ^４及びＲ^３は、上記式［Ｓ３］における場合と同様である。 The diamines having side chain structures represented by the above formulas [S1] to [S3] are each represented by the structure of the following formula [1-S1]-[1-S3].

In the above formula [1-S1], X ¹ , X ² , G ¹ , G ² , R ¹ , m and n are the same as in the above formula [S1]. In the above formula [1-S2], X ³ and R ² are the same as in the above formula [S2]. In the above formula [1-S3], X ⁴ and R ³ are the same as in the above formula [S3].

上記式［１］中、Ｘは、単結合、－Ｏ－、－Ｃ（ＣＨ_３）_２－、－ＮＨ－、－ＣＯ－、－ＮＨＣＯ－、－ＣＯＯ－、－（ＣＨ_２）_ｍ－、－ＳＯ_２－又はそれらの任意の組み合わせからなる２価の有機基を表す。なかでも、Ｘは、単結合、－Ｏ－、－ＮＨ－、－Ｏ－（ＣＨ_２）_ｍ－Ｏ－であるのが好ましい。「それらの任意の組み合わせ」の例としては、－Ｏ－（ＣＨ_２）_ｍ－Ｏ－、－Ｏ－Ｃ（ＣＨ_３）_２－、－ＣＯ－（ＣＨ_２）_ｍ－、－ＮＨ－（ＣＨ_２）_ｍ－、－ＳＯ_２－（ＣＨ_２）_ｍ－、－ＣＯＮＨ－（ＣＨ_２）_ｍ－、－ＣＯＮＨ－（ＣＨ_２）_ｍ－ＮＨＣＯ－、－ＣＯＯ－（ＣＨ_２）_ｍ－ＯＣＯ－等が挙げられる。ｍは１～８の整数である。 <Other diamines: Diamines having a characteristic side chain structure of a two-side chain type that exhibits vertical alignment>
When used as a crystal aligning agent in a VA type liquid crystal display element, a specific polymer can also be prepared using a two-side chain type diamine having two specific vertically aligned side chain structures.
The two-side chain diamine that may be included as such a diamine component is represented by the following formula [1], for example.

In the above formula [1], X is a single bond, -O-, -C(CH ₃ ) ₂ -, -NH-, -CO-, -NHCO-, -COO-, -(CH ₂ ) _m -, Represents a divalent organic group consisting of -SO ₂ - or any combination thereof. Among these, X is preferably a single bond, -O-, -NH-, or -O-(CH ₂ ) _m -O-. Examples of "any combination thereof" include -O-(CH ₂ ) _m -O-, -OC(CH ₃ ) ₂ -, -CO-(CH ₂ ) _m -, -NH-(CH ₂ ) _m -, -SO ₂ -(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -, -CONH-(CH ₂ ) _m -NHCO-, -COO-(CH ₂ ) _m -OCO-, etc. can be mentioned. m is an integer from 1 to 8.

上記式［１－１］中、Ｙ^１及びＹ^３は、それぞれ独立して、単結合、－（ＣＨ_２）_ａ－（ａは１～１５の整数である）、－Ｏ－、－ＣＨ_２Ｏ－、－ＣＯＯ－又は－ＯＣＯ－を表す。Ｙ^２は単結合又は－（ＣＨ_２）_ｂ－（ｂは１～１５の整数である）を表す。ただし、Ｙ^１又はＹ^３が単結合又は－（ＣＨ_２）_ａ－である場合、Ｙ^２は単結合である。また、Ｙ^１が－Ｏ－、－ＣＨ_２Ｏ－、－ＣＯＯ－又は－ＯＣＯ－であるか、及び／又はＹ^３が－Ｏ－、－ＣＨ_２Ｏ－、－ＣＯＯ－又は－ＯＣＯ－である場合、Ｙ^２は単結合又は－（ＣＨ_２）_ｂ－である。 In the above formula [1], the two Y's each independently represent the structure of the following formula [1-1].

In the above formula [1-1], Y ¹ and Y ³ each independently represent a single bond, -(CH ₂ ) _a - (a is an integer from 1 to 15), -O-, -CH ₂ Represents O-, -COO- or -OCO-. Y ² represents a single bond or -(CH ₂ ) _b - (b is an integer from 1 to 15). However, when Y ¹ or Y ³ is a single bond or -(CH ₂ ) _a -, Y ² is a single bond. Furthermore, Y ¹ is -O-, -CH ₂ O-, -COO- or -OCO-, and/or Y ³ is -O-, -CH ₂ O-, -COO- or -OCO-. In some cases, Y ² is a single bond or -(CH ₂ ) _b -.

In formula [1-1], Y ⁴ is at least one divalent cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring, and a heterocycle, or a divalent organic compound having 17 to 51 carbon atoms and having a steroid skeleton. represents a group. Any hydrogen atom forming the cyclic group may be an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, or a fluorine-containing alkyl group having 1 to 3 carbon atoms. It may be substituted with a group or a fluorine atom.

In the above formula [1-1], Y ⁵ represents at least one cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring, and a heterocycle. Any hydrogen atom forming the cyclic group may be an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, or a fluorine-containing alkyl group having 1 to 3 carbon atoms. It may be substituted with a group or a fluorine atom.

In the above formula [1-1], Y ⁶ is an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, and Represents at least one member selected from the group consisting of fluorine-containing alkoxy groups having 1 to 18 carbon atoms. n is an integer from 0 to 4.

In the above formula [1], Y may be at the meta or ortho position from the position of X, but is preferably at the ortho position. That is, the above formula [1] is preferably the following formula [1'].

In the above formula [1], the two amino groups (-NH ₂ ) may be located at any position on the benzene ring, but are represented by the following formulas [1]-a1 to [1]-a3. The position represented by the following formula [1]-a1 is preferable, and the position represented by the following formula [1]-a1 is more preferable. In the following formula, X is the same as in the above formula [1]. Note that the following formulas [1]-a1 to [1]-a3 explain the positions of two amino groups, and the notation of Y in the above formula [1] is omitted.

Therefore, based on the above formulas [1'] and [1]-a1 to [1]-a3, the above formula [1] can be selected from the following formulas [1]-a1-1 to [1]-a3-2. It is preferable to have a structure represented by the following formula [1]-a1-1, and more preferably a structure represented by the following formula [1]-a1-1. In the following formula, X and Y are each the same as in formula [1].

Examples of the above formula [1-1] include the following formulas [1-1]-1 to [1-1]-22. Among these, as examples of the above formula [1-1], the following formulas [1-1]-1 to [1-1]-4, [1-1]-8, or [1-1]-10 are preferable. . In the following formula, * represents the bonding position with the phenyl group in the above formulas [1], [1'] and [1]-a1 to [1]-a3.

Since the diamine component contains a two-side chain diamine having a predetermined structure, the liquid crystal alignment film becomes a liquid crystal alignment film in which the ability to vertically align liquid crystals is less likely to deteriorate even when exposed to excessive heating. Moreover, since the diamine component contains the two-side chain diamine, the liquid crystal alignment film becomes such that even when the film is damaged by some foreign matter coming into contact with it, the ability to vertically align the liquid crystal is less likely to deteriorate. That is, since the diamine component contains the two-side chain diamine, it is possible to provide a liquid crystal aligning agent that provides a liquid crystal aligning film excellent in various above-mentioned properties.

<Other diamines: diamines with photoreactive side chains>
When used as a liquid crystal aligning agent in a PSA type liquid crystal display element, a specific polymer can also be prepared using a diamine having a photoreactive side chain for the purpose of increasing the reactivity of the polymerizable compound.
Such a diamine component may contain a diamine having a photoreactive side chain as another diamine. When the diamine component contains a diamine having a photoreactive side chain, the photoreactive side chain can be introduced into the specific polymer or other polymers.

Examples of the diamine having a photoreactive side chain include those represented by the following formula [VIII] or [IX].

In the above formulas [VIII] and [IX], the positions of the two amino groups (-NH ₂ ) may be any position on the benzene ring, for example, with respect to the side chain binding group, on the benzene ring. Examples include the 2,3 position, the 2,4 position, the 2,5 position, the 2,6 position, the 3,4 position, or the 3,5 position. From the viewpoint of reactivity when synthesizing polyamic acid, the 2,4 position, the 2,5 position, or the 3,5 position is preferable. Considering the ease of synthesizing the diamine, the 2,4 positions or the 3,5 positions are more preferable.

In the above formula [VIII], R ⁸ is a single bond, -CH ₂ -, -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N Represents (CH ₃ )-, -CON(CH ₃ )- or -N(CH ₃ )CO-. In particular, R ⁸ is preferably a single bond, -O-, -COO-, -NHCO-, or -CONH-.

In the above formula [VIII], R ⁹ represents a single bond or an alkylene group having 1 to 20 carbon atoms which may be substituted with a fluorine atom. -CH ₂ - of the alkylene group here may be optionally substituted with -CF ₂ - or -CH=CH-, and if any of the following groups are not adjacent to each other, these groups may be substituted. -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, divalent carbocycle or heterocycle. In addition, this divalent carbocycle or heterocycle can be specifically exemplified by the one represented by the following formula (1a).

In the above formula [VIII], R ⁹ can be formed by a conventional organic synthesis method, but from the viewpoint of ease of synthesis, a single bond or an alkylene group having 1 to 12 carbon atoms is preferable.

In the above formula [VIII], R ¹⁰ represents a photoreactive group selected from the group consisting of the following formula (1b). Among these, R ¹⁰ is preferably a methacrylic group, an acrylic group, or a vinyl group from the viewpoint of photoreactivity.

In the above formula [IX], Y ₁ represents -CH ₂ -, -O-, -CONH-, -NHCO-, -COO-, -OCO-, -NH- or -CO-. Y ₂ represents an alkylene group having 1 to 30 carbon atoms, a divalent carbocycle or a heterocycle. One or more hydrogen atoms in the alkylene group, divalent carbocycle or heterocycle may be substituted with a fluorine atom or an organic group. In Y ₂ , when the following groups are not adjacent to each other, -CH ₂ - may be substituted with these groups; -O-, -NHCO-, -CONH-, -COO-, -OCO-, -NH-, -NHCONH-, -CO-.

In the above formula [IX], Y ₃ represents -CH ₂ -, -O-, -CONH-, -NHCO-, -COO-, -OCO-, -NH-, -CO- or a single bond. Y ₄ represents a cinnamoyl group. Y ₅ represents a single bond, an alkylene group having 1 to 30 carbon atoms, a divalent carbocycle or a heterocycle. One or more hydrogen atoms in the alkylene group, divalent carbocycle or heterocycle may be substituted with a fluorine atom or an organic group. In Y ₅ , when the following groups are not adjacent to each other, -CH ₂ - may be substituted with these groups; -O-, -NHCO-, -CONH-, -COO-, -OCO-, -NH-, -NHCONH-, -CO-. Y ₆ represents a photopolymerizable group such as an acrylic group or a methacrylic group.

上記式（１ｃ）中、Ｘ^９及びＸ^１０は、それぞれ独立に、単結合、－Ｏ－、－ＣＯＯ－、－ＮＨＣＯ－又は－ＮＨ－である結合基を表す。Ｙは、フッ素原子で置換されていてもよい炭素数１～２０のアルキレン基を表す。 A specific example of the diamine having a photoreactive side chain represented by the above formula [VIII] or [IX] is the following formula (1c).

In the above formula (1c), X ⁹ and X ¹⁰ each independently represent a single bond, a bonding group that is -O-, -COO-, -NHCO-, or -NH-. Y represents an alkylene group having 1 to 20 carbon atoms which may be substituted with a fluorine atom.

Examples of the diamine having a photoreactive side chain include a diamine represented by the following formula [VII]. The diamine of formula [VII] has a site having a radical generating structure in its side chain. The radical-generating structure is decomposed by ultraviolet irradiation and radicals are generated.

In the above formula [VII], Ar represents at least one aromatic hydrocarbon group selected from the group consisting of phenylene, naphthylene and biphenylene, and the hydrogen atoms in these rings may be substituted with halogen atoms. Since Ar to which carbonyl is bonded is involved in the absorption wavelength of ultraviolet rays, when the wavelength is increased, a structure with a long conjugation length such as naphthylene or biphenylene is preferable. On the other hand, when Ar has a structure like naphthylene or biphenylene, the solubility may deteriorate, and in this case, the difficulty of synthesis increases. If the wavelength of ultraviolet rays is in the range of 250 nm to 380 nm, sufficient characteristics can be obtained even with a phenyl group, so it is most preferable for Ar to be a phenyl group.

In the above Ar, the aromatic hydrocarbon group may be provided with a substituent. As examples of the substituent here, electron-donating organic groups such as an alkyl group, a hydroxyl group, an alkoxy group, and an amino group are preferable.

In the above formula [VII], R ₁ and R ₂ each independently represent an alkyl group, an alkoxy group, a benzyl group, or a phenethyl group having 1 to 10 carbon atoms. In the case of an alkyl group or an alkoxy group, R ₁ and R ₂ may form a ring.

In the above formula [VII], T ₁ and T ₂ are each independently a single bond, -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O -, -N(CH ₃ )-, -CON(CH ₃ )- or -N(CH ₃ )CO- represents a bonding group.

In formula [VII], S represents a single bond, an unsubstituted or a fluorine-substituted alkylene group having 1 to 20 carbon atoms. -CH ₂ - or -CF ₂ - of the alkylene group here may be optionally substituted with -CH=CH-, and when any of the following groups are not adjacent to each other, these groups May be substituted; -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, divalent carbocycle, divalent heterocycle.

上記式（１ｄ）中、Ｒは水素原子又は炭素原子数１～４のアルキル基を表す。Ｒ_３は、－ＣＨ_２－、－ＮＲ－、－Ｏ－、又は－Ｓ－を表す。 In formula [VII], Q represents a structure selected from the following formula (1d).

In the above formula (1d), R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ₃ represents -CH ₂ -, -NR-, -O-, or -S-.

In the above formula [VII], Q is preferably an electron-donating organic group, and preferably an alkyl group, a hydroxyl group, an alkoxy group, an amino group, etc. as mentioned in the example of Ar above. If Q is an amino derivative, problems such as formation of a salt between the carboxylic acid group and the amino group generated during polymerization of polyamic acid, which is a precursor of polyimide, may occur. is more preferable.

In the above formula [VII], the positions of the two amino groups (-NH ₂ ) may be o-phenylenediamine, m-phenylenediamine or p-phenylenediamine, but from the viewpoint of reactivity with acid dianhydride. In this case, m-phenylenediamine or p-phenylenediamine is preferred.

Preferred specific examples of the above formula [VII] include the following formula from the viewpoint of ease of synthesis, high versatility, properties, etc. In addition, in the following formula, n is an integer of 2 to 8.

These diamines having a photoreactive side chain represented by the above formula [VII], [VIII] or [IX] can be used alone or in a mixture of two or more. Depending on the characteristics such as liquid crystal orientation, pretilt angle, voltage holding characteristics, and accumulated charge when used as a liquid crystal alignment film, and the response speed of liquid crystal when used as a liquid crystal display element, one type or a mixture of two or more types may be used. If they are used, or if two or more types are used as a mixture, the ratio thereof may be adjusted as appropriate.

<Other diamines: diamines other than those listed above>
Diamines other than the above that may be included in the diamine component for obtaining the specific polymer are not limited to the diamines having the above specific structure. Examples of diamines other than those mentioned above include those represented by the following formula [2].

In the above formula [2], A ₁ and A ₂ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. . Among these, from the viewpoint of monomer reactivity, A ₁ and A ₂ are preferably a hydrogen atom or a methyl group. Further, examples of the structure of Y ¹¹ include the following formulas (Y-1) to (Y-178).

In the above formula, n is an integer from 1 to 6 unless the range of n is specifically stated. Moreover, in the above formula, Me represents a methyl group.

上記式中、Ｂｏｃは、ｔｅｒｔ－ブトキシカルボニル基を表す。

In the above formula, Boc represents a tert-butoxycarbonyl group.

Two or more diamines other than those described above can be used in combination. When the diamine component contains a diamine other than the above, the amount of the specific diamine relative to the other diamine in the specific polymer is 5 to 70 mol%, preferably 10 to 50 mol%, more preferably 10 to 40 mol%. Good.

The polyimide precursor used in the present invention is obtained from a reaction between a diamine component and a tetracarboxylic acid derivative, and examples thereof include polyamic acid and polyamic acid ester.
When a polyimide precursor containing a structural unit represented by formula (3) simultaneously contains a structural unit represented by formula (5), the structural unit represented by formula (3) is a combination of formula (3) and formula (5). It is preferably 10 mol % or more, more preferably 20 mol % or more, particularly preferably 30 mol % or more based on the total of (5).
The weight average molecular weight of the polyimide precursor used in the present invention is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and even more preferably 10,000 to 100,000. be.

Examples of the polyimide having a monovalent group represented by formula (1) include polyimides obtained by ring-closing the polyimide precursors described above. In this polyimide, the ring closure rate (also referred to as imidization rate) of the amic acid group does not necessarily have to be 100%, and can be arbitrarily adjusted depending on the use and purpose.
Examples of methods for imidizing the polyimide precursor include thermal imidization, in which a solution of the polyimide precursor is directly heated, and catalytic imidization, in which a catalyst is added to the solution of the polyimide precursor.

<Liquid crystal alignment agent>
Although the liquid crystal aligning agent of the present invention contains the above-mentioned specific polymer, it may contain two or more kinds of specific polymers having different structures. Moreover, in addition to the specific polymer, other polymers, ie, polymers not having a monovalent group represented by formula (1), may be contained. Polymer types include polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or its derivative, poly(styrene-phenylmaleimide) derivative, poly(meth)acrylate. etc. When the liquid crystal aligning agent of the present invention contains other polymers, the ratio of the specific polymer to the total polymer components is preferably 5% by mass or more, for example, 5 to 95% by mass.

A liquid crystal aligning agent generally takes the form of a coating liquid in order to form a uniform thin film. The liquid crystal aligning agent of the present invention is also preferably a coating liquid containing the above polymer component and an organic solvent that dissolves this polymer component. At that time, the concentration of the polymer in the liquid crystal aligning agent can be changed as appropriate depending on the thickness of the coating film to be formed. From the viewpoint of forming a uniform and defect-free coating film, the content is preferably 1% by mass or more, and from the viewpoint of storage stability of the solution, the content is preferably 10% by mass or less. Particularly preferred polymer concentrations are 2 to 8% by weight.

The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as the polymer component is uniformly dissolved therein. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, 1,3-dimethyl- These include imidazolidinone, methyl ethyl ketone, cyclohexanone, and cyclopentanone. Among them, it is preferable to use N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone.

In addition to the above-mentioned solvents, the organic solvent contained in the liquid crystal aligning agent of the present invention may be a solvent that improves the applicability when applying the liquid crystal aligning agent and the surface smoothness of the coating film. Specific examples of such organic solvents are listed below.

For example, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol , 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 2,6- Dimethyl-4-heptanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2, 3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, diisopropyl ether, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene Glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2- Pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 2,6-dimethyl-4-heptanone, 4,6-dimethyl-2-heptanone, 3-ethoxybutylacetate, 1-methylpentylacetate tert, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2-(methoxymethoxy)ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl Ether, ethylene glycol monohexyl ether, 2-(hexyloxy)ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1-(butoxyethoxy)propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, diethylene glycol Monoethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono Butyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, triethylene glycol, Ethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate , ethyl 3-ethoxypropionate, methylethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, lactic acid Examples include methyl ester, ethyl lactate, n-propyl ester, n-butyl ester, isoamyl lactate, and solvents represented by the above formulas [D-1] to [D-3].

Among them, the organic solvents include 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, and ethylene. Preference is given to using glycol monobutyl ether or dipropylene glycol dimethyl ether. The type and content of such a solvent are appropriately selected depending on the liquid crystal aligning agent coating device, coating conditions, coating environment, and the like.

The liquid crystal aligning agent of the present invention may additionally contain components other than the polymer component and the organic solvent. Such additional components include adhesion aids to improve the adhesion between the liquid crystal alignment film and the substrate and the adhesion between the liquid crystal alignment film and the sealing material, crosslinking agents to increase the strength of the liquid crystal alignment film, and liquid crystal Examples include dielectric materials and conductive materials for adjusting the dielectric constant and electrical resistance of the alignment film. Specific examples of these additional components include poor solvents and crosslinkable compounds disclosed in paragraph [0104] on page 53 to paragraph [0116] on page 60 of International Publication No. 2015/060357.

Compounds that improve the adhesion between the liquid crystal alignment film and the substrate include functional silane-containing compounds and epoxy group-containing compounds, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, and 3-aminopropyltriethoxysilane. Glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2- (aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl- 3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4 ,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N -Benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5, 6-tetraglycidyl-2,4-hexanediol, N,N,N',N',-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane or N, Examples include N,N',N',-tetraglycidyl-4,4'-diaminodiphenylmethane.

The liquid crystal alignment agent of the present invention may contain the following additives in order to increase the mechanical strength of the liquid crystal alignment film.

The above-mentioned additive is preferably 0.1 to 30 parts by mass based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. If the amount is less than 0.1 parts by mass, no effect can be expected, and if it exceeds 30 parts by mass, the alignment of liquid crystals will be deteriorated, so it is more preferably 0.5 to 20 parts by mass.

In addition to the above, the liquid crystal aligning agent of the present invention includes polymers other than the specific polymers described in the present invention, dielectrics for the purpose of changing electrical properties such as permittivity and conductivity of the liquid crystal aligning film, and liquid crystal aligning films. silane coupling agents for the purpose of improving the adhesion between the film and the substrate, crosslinking compounds for the purpose of increasing the hardness and density of the film when it is made into a liquid crystal alignment film, and even polyimide precursors used when baking the coating film. An imidization accelerator or the like may be included for the purpose of efficiently promoting imidization by heating.

<Liquid crystal alignment film>
The liquid crystal aligning film of the present invention is obtained from the liquid crystal aligning agent. An example of a method for obtaining a liquid crystal alignment film from a liquid crystal alignment agent is to apply a liquid crystal alignment agent in the form of a coating liquid to a substrate, dry it, and bake it, then apply a rubbing treatment method or photo alignment treatment to the film obtained. An example of this method is to perform orientation treatment using a method. In addition, in the VA method, it can also be used as it is without performing alignment treatment.

The substrate to which the liquid crystal aligning agent is applied is not particularly limited as long as it is a highly transparent substrate, and in addition to glass substrates and silicon nitride substrates, plastic substrates such as acrylic substrates and polycarbonate substrates can also be used. In this case, it is preferable to use a substrate on which ITO electrodes and the like for driving the liquid crystal are formed, from the viewpoint of process simplification. Furthermore, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used as long as only one substrate is used, and a material that reflects light such as aluminum can also be used for the electrodes in this case.

Industrially, common methods for applying the liquid crystal aligning agent include screen printing, offset printing, flexo printing, and inkjet methods. Other coating methods include a dip method, a roll coater method, a slit coater method, a spinner method, and a spray method, and these may be used depending on the purpose.

After applying the liquid crystal aligning agent onto the substrate, the solvent is evaporated and baked using a heating means such as a hot plate, a thermal circulation oven, an IR (infrared) oven, or the like. Any temperature and time can be selected for the drying and baking steps after applying the liquid crystal aligning agent. Although the drying step is not necessarily required, it is preferable to perform the drying step if the time from application to baking is not constant for each substrate or if baking is not performed immediately after coating. This drying may be carried out as long as the solvent is removed to the extent that the shape of the coating film is not deformed due to transportation of the substrate, etc., and the drying method may be, for example, hot drying at a temperature of 40°C to 150°C, preferably 60°C to 100°C. The method includes drying on a plate for 0.5 minutes to 30 minutes, preferably 1 minute to 5 minutes.

The firing temperature of the coating film formed by applying the liquid crystal aligning agent is, for example, 100 to 350°C, preferably 120 to 300°C, and more preferably 150 to 250°C. The firing time is 5 minutes to 240 minutes, preferably 10 minutes to 90 minutes, and more preferably 20 minutes to 90 minutes. Heating can be performed by a commonly known method, such as a hot plate, hot air circulation oven, infrared oven, etc.
The thickness of the liquid crystal alignment film after firing is preferably 5 to 300 nm, more preferably 10 to 200 nm, since the reliability of the liquid crystal display element may decrease if it is too thin.

When manufacturing a TN type, STN type, IPS type, or FFS type liquid crystal display element, a treatment is performed to impart liquid crystal alignment ability to the coating film formed in the above steps. Orientation ability imparting treatments include rubbing treatment, in which the coating film is rubbed in a certain direction with a roll wrapped with cloth made of fibers such as nylon, rayon, or cotton, and photo-alignment treatment, in which the coating film is irradiated with polarized or non-polarized radiation. Examples include processing. On the other hand, when manufacturing a VA type liquid crystal display element, the coating film formed in the above step can be used as a liquid crystal alignment film as it is, but the coating film may be subjected to an alignment ability imparting treatment.

In the photo-alignment treatment, as the radiation irradiated to the coating film, for example, ultraviolet rays and visible light including light with a wavelength of 150 to 800 nm can be used. If the radiation is polarized, it may be linearly polarized or partially polarized. Further, when the radiation used is linearly polarized light or partially polarized light, irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these may be performed. When irradiating non-polarized radiation, the direction of irradiation is oblique.

Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, excimer lasers, and LED lamps. Ultraviolet light in a preferred wavelength range can be obtained by using a light source in conjunction with, for example, a filter, a diffraction grating, or the like. The radiation dose is preferably 100 to 50,000 J/m ² , more preferably 300 to 20,000 J/m ² .

The coating film may be irradiated with light while the coating film is being heated in order to increase the reactivity. The temperature during heating is usually 30 to 250°C, preferably 40 to 200°C, more preferably 50 to 150°C.

In the photo-alignment treatment, heat treatment may be performed during light irradiation, or heat treatment may be performed after the photo-alignment treatment. The heating temperature at this time is preferably 80 to 300°C, more preferably 120 to 250°C. The heating time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. Furthermore, instead of the heat treatment, a cleaning treatment using an organic solvent or water may be performed, or the cleaning treatment and the heat treatment may be combined.

After the rubbing treatment, the liquid crystal alignment film is further treated by irradiating a part of the liquid crystal alignment film with ultraviolet rays to change the pretilt angle of a part of the liquid crystal alignment film, or by changing the pretilt angle of a part of the liquid crystal alignment film surface. After forming a resist film, a rubbing process may be performed in a direction different from the previous rubbing process, and then a process of removing the resist film may be performed so that the liquid crystal alignment film has different liquid crystal alignment abilities for each region. In this case, it is possible to improve the visibility characteristics of the resulting liquid crystal display element.

A liquid crystal alignment film suitable for a VA type liquid crystal display element can also be suitably used for a PSA (Polymer Sustained Alignment) type liquid crystal display element.

The liquid crystal alignment film of the present invention is also suitable as a liquid crystal alignment film for a liquid crystal display element of a transverse electric field method such as an IPS method or a FFS (Fringe Field Switching) method, and is suitable for liquid crystal alignment of a liquid crystal display element of a VA method, especially a PSA mode. It is also useful as a membrane.

<Liquid crystal display element>
The liquid crystal display element of the present invention is obtained by obtaining a substrate with a liquid crystal alignment film obtained from the above-mentioned liquid crystal aligning agent, then producing a liquid crystal cell by a known method, and using the liquid crystal cell to form an element. Specific examples of liquid crystal display elements that can be manufactured include two substrates arranged to face each other, a liquid crystal layer provided between the substrates, and a liquid crystal display device provided between the substrates and the liquid crystal layer according to the present invention. This is a liquid crystal display element comprising a liquid crystal cell having the above liquid crystal alignment film formed of a liquid crystal agent. More specifically, a liquid crystal alignment film is formed by applying the liquid crystal alignment agent of the present invention onto two substrates and baking it, and the two substrates are arranged so that the liquid crystal alignment films face each other, It is a liquid crystal display element in which a liquid crystal layer made of liquid crystal is sandwiched between these two substrates, that is, a liquid crystal layer is provided in contact with a liquid crystal alignment film. This is a liquid crystal display element that includes a liquid crystal cell that is manufactured by irradiating ultraviolet rays while applying a voltage to the layers.

As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. Specifically, transparent substrates are prepared, and then a liquid crystal alignment film is formed on each substrate under the conditions described above. As mentioned above, the substrate is usually a substrate on which a transparent electrode for driving liquid crystal is formed. Specific examples include the same substrates as those described for the liquid crystal alignment film above.

A common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be, for example, ITO electrodes, and are patterned to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a film made of SiO ₂ --TiO ₂ formed by a sol-gel method.

In a PSA mode liquid crystal display element, it is possible to operate even in a structure in which a line/slit electrode pattern of, for example, 1 to 10 μm is formed on one side substrate, and no slit pattern or protrusion pattern is formed on the opposite substrate. With this liquid crystal display element, the manufacturing process can be simplified and high transmittance can be obtained.

When manufacturing an IPS type or FFS type liquid crystal display element, the electrode forming surface of the substrate is provided with electrodes made of a transparent conductive film or metal film patterned in a comb-tooth shape, and the counter substrate is not provided with electrodes. A coating film is formed by applying a liquid crystal aligning agent to one surface of the substrate, and then heating each coating surface. As the metal film, for example, a film made of metal such as chromium can be used.

In a high-performance element such as a TFT type element, an element such as a transistor is formed between an electrode for driving a liquid crystal and a substrate.

In the case of a transmissive type liquid crystal display element, it is common to use a substrate like the one described above, but in the case of a reflective type liquid crystal display element, an opaque substrate such as a silicon wafer can also be used if only one side of the substrate is used. It is possible. In this case, a material such as aluminum that reflects light can also be used for the electrodes formed on the substrate.

The liquid crystal material constituting the liquid crystal layer of the vertical alignment liquid crystal display element is not particularly limited, and liquid crystal materials used in conventional vertical alignment systems, such as MLC-6608, MLC-6609, and MLC-3022 manufactured by Merck & Co., Ltd. Negative type liquid crystal such as can be used. Furthermore, in the PSA mode, MLC-3023, which is a liquid crystal containing a polymerizable compound, can be used. In addition, for example, a liquid crystal containing a polymerizable compound as represented by the following formula can be used.

The liquid crystal material constituting the liquid crystal layer of a horizontal alignment type liquid crystal display element such as IPS or FFS is a liquid crystal material conventionally used in a horizontal alignment type, such as negative-positive type liquid crystal materials such as MLC-2003 and MLC-2041 manufactured by Merck & Co., Ltd. It is also possible to use a negative type liquid crystal such as liquid crystal or MLC-6608.

Known methods can be used to sandwich the liquid crystal layer between two substrates. For example, prepare a pair of substrates on which a liquid crystal alignment film is formed, and sprinkle spacers such as beads on the liquid crystal alignment film of one substrate so that the surface on which the liquid crystal alignment film is formed is on the inside. One method is to bond the other substrate and inject liquid crystal under reduced pressure for sealing. In addition, a pair of substrates on which a liquid crystal alignment film is formed is prepared, and after scattering spacers such as beads on the liquid crystal alignment film of one substrate, liquid crystal is dropped, and then the side on which the liquid crystal alignment film is formed is A liquid crystal cell can also be produced by bonding and sealing the other substrate so that the two substrates are on the inside. The thickness of the spacer is preferably 1 to 30 μm, more preferably 2 to 10 μm.

In the PSA mode method, after a liquid crystal is sandwiched, a liquid crystal cell is produced by irradiating ultraviolet rays while applying a voltage to a liquid crystal alignment film and a liquid crystal layer. This step includes, for example, a method in which an electric field is applied to the liquid crystal alignment film and the liquid crystal layer by applying a voltage between electrodes installed on the substrate, and ultraviolet rays are irradiated while this electric field is maintained. Here, the voltage applied between the electrodes is, for example, 5 to 30 Vp-p or 2.5 to 15V DC, preferably 10 to 30Vp-p or 5 to 15V DC. Further, as the light to be irradiated, ultraviolet rays containing light with a wavelength of 300 to 400 nm are preferable. The light source of the irradiation light is as described above. The amount of ultraviolet irradiation is, for example, 1 to 60 J, preferably 40 J or less, and the smaller the amount of ultraviolet irradiation, the more it is possible to suppress the decrease in reliability caused by the destruction of the members constituting the liquid crystal display element, and to reduce the time of ultraviolet irradiation. This is preferable because it increases manufacturing efficiency.

As mentioned above, when the liquid crystal alignment film and the liquid crystal layer are irradiated with ultraviolet rays while applying a voltage, the polymerizable compounds react to form a polymer, and this polymer memorizes the direction in which the liquid crystal molecules are tilted. , the response speed of the obtained liquid crystal display element can be increased. In addition, when ultraviolet rays are irradiated while applying a voltage to the liquid crystal alignment film and the liquid crystal layer, a polyimide precursor having a side chain that vertically aligns the liquid crystal and a photoreactive side chain, and this polyimide precursor can be transformed into an imide. The photoreactive side chains of at least one kind of polymer selected from the polyimide obtained by the oxidation process and the photoreactive side chains of the polymer react with the polymerizable compound. Response speed can be increased.

After the above steps are completed, a polarizing plate is installed in the liquid crystal cell. Specifically, it is preferable to attach a pair of polarizing plates to the surfaces of the two substrates opposite to the liquid crystal layer.

The liquid crystal aligning film and liquid crystal display element of the present invention are not limited as long as the liquid crystal aligning agent of the present invention is used, and may be produced by other known methods. The process of obtaining a liquid crystal display element from a liquid crystal aligning agent is disclosed, for example, in Japanese Patent Publication No. 2015-135393, pages 17 [0074] to 19 pages [0081].

The liquid crystal display element of the present invention can be effectively applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, It can be used in various display devices such as various monitors, liquid crystal televisions, and information displays.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. The meanings of the abbreviations of compounds used in the examples are shown below.
(acid dianhydride)
BODA: Bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic dianhydride CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride (diamine)
PDA: p-phenylenediamine Side chain diamine represented by the following formulas DA-1 to DA-4

＜溶媒＞
ＮＭＰ：Ｎ－メチル－２－ピロリドン
ＢＣＳ：ブチルセロソルブ
＜添加剤＞
３ＡＭＰ：３－ピコリルアミン

<Solvent>
NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve <additive>
3AMP: 3-picolylamine

<Molecular weight measurement of polyimide>
Measuring device: Room temperature gel permeation chromatography (GPC) (SSC-7200) manufactured by Senshu Kagaku Co., Ltd.
Column: Shodex column (KD-803, KD-805), column temperature: 50°C, eluent: N,N'-dimethylformamide (as an additive, lithium bromide hydrate (LiBr.H ₂ O) ) is 30 mmol/L, phosphoric acid/anhydrous crystal (o-phosphoric acid) is 30 mmol/L, tetrahydrofuran (THF) is 10 ml/L),
Flow rate: 1.0ml/min,
Standard samples for creating a calibration curve: TSK standard polyethylene oxide manufactured by Tosoh Corporation (molecular weight approximately 9000,000, 150,000, 100,000, 30,000) and polyethylene glycol manufactured by Polymer Laboratory (molecular weight approximately 12,000, 4) ,000, 1,000).

<Measurement of imidization rate>
Put 20 mg of polyimide powder into an NMR sample tube (NMR sampling tube standard φ5, manufactured by Kusano Kagaku Co., Ltd.), add 1.0 ml of deuterated dimethyl sulfoxide (DMSO-d ₆ , 0.05% TMS mixture), and apply ultrasonic waves. It was completely dissolved. This solution was subjected to proton NMR measurement at 500 MHz using an NMR measuring device (JNW-ECA500) manufactured by JEOL Datum.
(Chemistry) The imidization rate is determined by determining a proton derived from a structure that does not change before and after imidization as a reference proton, and by calculating the peak integrated value of this proton and the NH group of amic acid that appears around 9.5 to 10.0 ppm. It was calculated using the following formula using the proton peak integrated value. In the formula, x is the integrated value of the proton peak derived from the NH group of the amic acid, y is the integrated value of the reference proton peak, and α is the integrated value of the proton peak derived from the NH group of the amic acid, and α is the integrated value of the amic acid in the case of polyamic acid (imidization rate is 0%). This is the ratio of the number of standard protons to one proton of the NH group.
Imidization rate (%) = (1-α・x/y)×100

DA-1 is a new compound that has not been published in literature, and the synthesis method will be described in detail below.
The product described in Synthesis Example 1 below was identified by ¹ H-NMR analysis (analysis conditions are as follows).
Equipment: Varian NMR System 400 NB (400 MHz)
Measurement solvent: DMSO- _d6
Reference substance: Tetramethylsilane (TMS) (δ0.0 ppm for ¹ H)

<<Synthesis Example 1 Synthesis of DA-1>>

<Synthesis of compound [1]>
Tetrahydrofuran (130 g) and triethylamine (19.8 g, 0.196 mol) were added to 4-(2-hydroxyethoxy)benzaldehyde (25.0 g, 0.150 mol), and the mixture was heated and stirred at 50°C. A dropping funnel was charged with 2,4-dinitrofluorobenzene (31.0 g, 0.167 mol) and tetrahydrofuran (25.0 g), which were added dropwise and stirred at 50° C. overnight. After the reaction was completed, the reaction solution was concentrated, and a 1/1 methanol/water mixed solvent (110 g) was added to the obtained crude to wash the slurry. This was filtered and cake washed with methanol (50g). Tetrahydrofuran (200 g) was added to the obtained crystals, heated and stirred at 55° C., and methanol (200 g) was added while cooling to room temperature to cause crystallization. This was filtered, cake washed with methanol (100 g), and the obtained crystals were dried to obtain compound [1] (yield: 48.4 g, 0.146 mol, yield 97%).
^1H -NMR (400MHz) in DMSO- _d6 : 9.89 (s, 1H), 8.78 (d, J=2.8Hz, 1H), 8.56-8.53 (m, 1H), 7.89-7.87 (m, 2H), 7.69 (d, J=9.6Hz, 1H), 7.19-7.16 (m, 2H), 4.75-4.74 (m , 2H), 4.51-4.50 (m, 2H).

<Synthesis of compound [2]>
Compound [1] (15.0 g, 0.0451 mol), para-toluenesulfonic acid monohydrate (0.088 g, 0.463 mmol), ethylene glycol (6.26 g, 0.101 mol), toluene (91 .5 g) and stirred for 2 hours under heating and reflux conditions using a Dean-Stark apparatus. After the reaction was completed, the target product crystallized when the reaction solution was returned to room temperature. Toluene/water = 1/1 mixed solvent (180 g) was added to the obtained crystals to wash the slurry, and the obtained crystals were filtered. The cake was washed with toluene (180 g). The obtained crystals were dried to obtain compound [2] (yield: 16.9 g, 0.0448 mol, yield 99%).
¹ H-NMR (400 MHz) in DMSO-d ₆ :8.78 (s, 1H), 8.55-8.52 (m, 1H), 7.70-7.67 (m, 1H), 7. 36 (d, J = 8.8Hz, 2H), 6.97 (d, J = 8.8Hz, 2H), 5.66 (s, 1H), 4.71-4.69 (m, 2H), 4.39-4.37 (m, 2H), 4.08-4.00 (m, 2H), 3.96-3.88 (m, 2H).

<Synthesis of DA-1>
Tetrahydrofuran (477 g) was added to Compound [2] (15.9 g, 0.0423 mol), and the mixture was replaced with nitrogen. 5% Palladium Carbon (hydrous product) (1.27 g) was added and the mixture was replaced with nitrogen. After installation, the mixture was heated at 40°C and stirred overnight. After the reaction was completed, the filtrate was passed through a membrane filter to remove palladium carbon, and the filtrate was concentrated to precipitate crystals. The obtained crystals were slurry washed by adding hexane (200 g), filtered, and cake washed with hexane (100 g). The obtained crystals were dried to obtain DA-1 (yield: 12.1 g, 0.0381 mol, yield 96%).
¹ H-NMR (400MHz) in DMSO-d ₆ :7.38-7.34 (m, 2H), 7.00-6.96 (m, 2H), 6.55 (d, J = 8.4Hz , 1H), 5.94 (d, J = 2.4Hz, 1H), 5.76-5.74 (m, 1H), 5.66 (s, 1H), 4.48 (br, 2H), 4.42 (br, 2H), 4.25-4.22 (m, 2H), 4.09-4.07 (m, 2H), 4.06-4.02 (m, 2H), 3. 93-3.90 (m, 2H).

<Example 1>
BODA (3.75 g, 15.0 mmol), DA-1 (4.75 g, 15.0 mmol), and DA-3 (5.71 g, 15.0 mmol) were dissolved in NMP (56.8 g) and heated at 60°C. After reacting for 5 hours, CBDA (2.88 g, 14.7 mmol) and NMP (11.5 g) were added and reacted at 40° C. for 10 hours to obtain a polyamic acid solution.
NMP (10.0 g) and BCS (13.3 g) were added to this polyamic acid (PAA) solution (10 g), diluted to 6% by weight, and stirred at room temperature for 3 hours to prepare a liquid crystal alignment agent (A-1). .

<Example 2>
After adding NMP to the polyamic acid solution (50 g) obtained in Example 1 and diluting it to 8% by mass, acetic anhydride (8.9 g) and pyridine (2.8 g) were added as imidization catalysts, and the mixture was heated at 70°C. The reaction was allowed to proceed for 3 hours. This reaction solution was poured into methanol (550 ml), and the resulting precipitate was filtered off. This precipitate was washed with methanol and dried under reduced pressure at 100°C to obtain polyimide powder (P-1). The imidization rate of this polyimide was 75%, the number average molecular weight was 18,000, and the weight average molecular weight was 38,000.
NMP (22.0 g) was added to the obtained polyimide powder (P-1) (3.0 g) and dissolved by stirring at 70° C. for 20 hours. A liquid crystal aligning agent (S-1) was obtained by adding 3.0 g of 3AMP (1 mass% NMP solution), NMP (2.0 g), and BCS (20.0 g) to this solution and stirring at room temperature for 5 hours. .

<Comparative Examples 1 to 4>
Liquid crystal alignment agents (A-2, A-3), (S-2, S-3) was prepared.

<Comparative example 5>
BODA (3.75 g, 15.0 mmol), DA-4 (4.78 g, 15.0 mmol), and DA-3 (5.71 g, 15.0 mmol) were dissolved in NMP (91.7 g) and heated at 60°C. After reacting for 5 hours, CBDA (2.88 g, 14.7 mmol) and NMP (21.1 g) were added and reacted at 40° C. for 10 hours, resulting in gelation of the reaction solution.

<Evaluation of rubbing resistance>
A liquid crystal aligning agent was spin-coated on the ITO surface of a glass substrate having ITO electrodes on the entire surface, and was temporarily dried on a hot plate at 70° C. for 90 seconds. Thereafter, baking was performed in an IR oven at 230° C. for 30 minutes to form a coating film with a thickness of 100 nm, thereby obtaining a substrate with a liquid crystal alignment film. This liquid crystal alignment film was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm/sec, pushing length: 0.6 mm). This board was observed under a microscope, and if there were no streaks or scrapes on the film surface due to rubbing, it was rated "good", if there were only a few scraps visible, it was rated "good", and if there were no severe streaks or scrapes, it was rated "good". Those that failed were evaluated as "poor."

The above-mentioned rubbing resistance evaluation was carried out for liquid crystal alignment agents A-1 to S-3. The results are shown in Table 2 below.

As shown in Table 2, in the polymer using a diamine having a cyclic acetal group, no streaks were observed due to the rubbing treatment, and the results were very good. On the other hand, in the comparative example that does not contain a cyclic acetal group, many streaks and scrapes due to rubbing were observed.
This is considered to be because aldehyde groups were generated during firing of the alignment film, and a crosslinking reaction occurred between the polymers.

Further, as shown in Comparative Example 5, when the aldehyde protecting group site is not cyclic, aldehyde is generated by the acid or heat during polymerization, and reacts with the amine to cause three-dimensional crosslinking and gelation. Therefore, the moiety of the aldehyde protecting group needs to be cyclic.

Claims (7)

A liquid crystal aligning agent characterized by containing a polymer having a cyclic acetal group represented by the following formula (1).

(R ¹ represents hydrogen or a monovalent organic group, n is an integer from 0 to 2, and * represents a site bonded to another group.) The liquid crystal aligning agent according to claim 1, wherein the polymer having a cyclic acetal group represented by the formula (1) is a polymer derived from a diamine represented by the following formula (2).

(The definitions of R ¹ and n are the same as in the above formula (1). Ar represents an aromatic hydrocarbon group selected from phenylene, naphthylene, and biphenylene, which may be substituted with an organic group, The hydrogen atom may be replaced with a halogen atom.T ¹ and T ² are each independently a single bond or -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N(CH ₃ )-, -CON(CH ₃ )-, -N(CH ₃ )CO-, and W is a single bond or unsubstituted or substituted with a fluorine atom. an alkylene group having 1 to 20 carbon atoms (however, -CH ₂ - or -CF ₂ - in the alkylene group may be optionally replaced with -CH=CH-, and any of the following groups are adjacent to each other) In cases where they do not match, these groups may be substituted; -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, divalent carbocycle, divalent heterocycle ring.) is.). Claim 1, wherein the polymer having a cyclic acetal group is at least one selected from the group consisting of a polyimide precursor containing a structural unit represented by the following formula (3), and a polyimide that is an imidized product thereof. The liquid crystal alignment agent described.

(X ¹ represents a tetravalent organic group derived from a tetracarboxylic acid derivative. Y ¹ represents a divalent organic group derived from a diamine containing the structure of formula (1). R ² represents a hydrogen atom or the number of carbon atoms. Represents an alkyl group of 1 to 5.) The liquid crystal aligning agent according to claim 3 , wherein in the formula (3), the structure of ^X1 is at least one selected from the following structures.

The liquid crystal aligning agent according to claim 3 or 4, wherein the structural unit represented by the formula (3) is 10 mol% or more based on the total structural units of the polymer. A liquid crystal aligning film obtained from the liquid crystal aligning agent according to any one of claims 1 to 5. A liquid crystal display element comprising the liquid crystal alignment film according to claim 6.