JPWO2019189637A1 - New liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

Provided are a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element capable of obtaining a liquid crystal display element having excellent voltage holding characteristics and high temperature and high humidity resistance. A liquid crystal alignment agent containing a polymer (P) having a partial structure represented by the following formula (I-1) or formula (I-2). [Chemical formula 1] (A is a (n + 1) -valent hydrocarbon group having 1 to 18 carbon atoms, or -O-, -COO-, -CO- or -NHCO- between carbon-carbon bonds of the hydrocarbon group. S represents a single bond or a hydrocarbon group having 1 to 4 carbon atoms. P1 represents a hydroxyl group protected by a thermal desorption group. N is an integer of 1 to 5, and m. Is an integer of 1 to 2. When m is 1, R1 represents a hydrocarbon group having 1 to 4 carbon atoms, and when m is 2, R1 represents a hydrogen atom. * Is a bond that bonds to a hydrocarbon group. Shows.)

Description

The present invention relates to a liquid crystal alignment agent capable of obtaining a liquid crystal display element having excellent voltage holding characteristics and high temperature and high humidity resistance, a liquid crystal alignment film using the same, and a liquid crystal display element.

Liquid crystal display elements are widely used as display units for personal computers, mobile phones, smartphones, televisions, and the like. The liquid crystal display element is, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that apply an electric field to the liquid crystal layer, and a liquid crystal alignment film that controls the orientation of liquid crystal molecules in the liquid crystal layer. , A thin film transistor (TFT) for switching an electric signal supplied to a pixel electrode is provided.
Conventionally, as the definition of a liquid crystal display element has been increased, there has been a demand for suppressing a decrease in contrast of the liquid crystal display element and reducing an afterimage phenomenon. , High voltage retention, suppression of afterimages generated by AC drive, small residual charge when DC voltage is applied, and / or quick relaxation of accumulated residual charge due to DC voltage are becoming increasingly important.

Conventionally, as a liquid crystal alignment film, a polyimide-based liquid crystal alignment film obtained by applying a polyimide precursor such as polyamic acid (polyamic acid) or a liquid crystal alignment agent containing a solution of soluble polyimide as a main component to a glass substrate or the like and firing the liquid crystal alignment film is mainly used. Has been done.
In order to meet the above requirements, various proposals have been made for polyimide-based liquid crystal alignment films. For example, as a liquid crystal alignment film in which the time until the afterimage generated by the DC voltage disappears is short, a liquid crystal alignment agent containing a tertiary amine having a specific structure in addition to the polyamic acid or the imide group-containing polyamic acid is used (for example). Patent Document 1) and those using a liquid crystal aligning agent containing a soluble polyimide using a specific diamine compound having a pyridine skeleton as a raw material (see, for example, Patent Document 2) have been proposed. Further, as a liquid crystal alignment film having a high voltage retention rate and a short time until the afterimage generated by the DC voltage disappears, it contains one carboxylic acid group in the molecule in addition to polyamic acid and its imidized polymer. A liquid crystal aligning agent containing a very small amount of a compound selected from the group consisting of a compound, a compound containing one carboxylic acid anhydride group in the molecule, and a compound containing one tertiary amino group in the molecule is used. (See, for example, Patent Document 3) has been proposed.

Further, as a liquid crystal alignment film having excellent liquid crystal orientation, high voltage retention, low afterimage, excellent reliability, and high pretilt angle, a tetracarboxylic acid having a specific structure of tetracarboxylic dianhydride and cyclobutane. Known are those using a liquid crystal alignment agent containing a polyamic acid obtained from a dianhydride and a specific diamine compound and an imidized polymer thereof (see, for example, Patent Document 4). Further, as a method of suppressing the afterimage caused by AC drive generated in the liquid crystal display element of the transverse electric field drive type, a method of using a specific liquid crystal alignment film having good liquid crystal orientation and large interaction with liquid crystal molecules (patented). Reference 5) has been proposed.

Japanese Patent Application Laid-Open No. 9-316200 Japanese Patent Application Laid-Open No. 10-104633 Japanese Patent Application Laid-Open No. 8-76128 Japanese Patent Application Laid-Open No. 9-138414 Japanese Patent Application Laid-Open No. 11-38415

However, in recent years, with the improvement of the performance of liquid crystal display elements such as smartphones, the characteristics expected of the liquid crystal alignment film have become more severe, and especially at a high level, the substrate can be used for a long period of time even under high temperature and high humidity. There is a demand for a liquid crystal aligning agent capable of obtaining a liquid crystal display element having a property of maintaining a high voltage while maintaining close contact with the liquid crystal. Further, the manufacturing line of the liquid crystal display element has become very large in recent years, and uneven firing temperature, uneven coating, etc. are likely to occur in the manufacturing process of the liquid crystal alignment film. Therefore, the vertical alignment type liquid crystal display element is required to have a high vertical alignment ability that can withstand a harsh manufacturing process.

The present invention has been made in view of the above, and uses a liquid crystal aligning agent capable of obtaining a liquid crystal display element having adhesion to a substrate, voltage holding characteristics, and high temperature and high humidity resistance at a higher level. It is an object of the present invention to provide a liquid crystal alignment film and a liquid crystal display element. Another object of the present invention is to provide a liquid crystal alignment film having a high vertical alignment ability that exhibits a stable pretilt angle even under a harsh manufacturing process.

As a result of diligent research to achieve the above object, the present inventor has found that a liquid crystal aligning agent containing a polymer having a specific partial structure is extremely effective in achieving the above object. , The present invention has been completed.

（Ａは炭素数１〜１８の（ｎ+１）価の炭化水素基、又は炭化水素基の炭素―炭素結合間に−Ｏ−、−ＣＯＯ−、−ＣＯ−、又は−ＮＨＣＯ−を有する基を表す。Ｓは、単結合又は炭素数１〜４の炭化水素基を表す。Ｐ_１は熱脱離性基で保護された水酸基を表す。ｎは１〜５の整数であり、ｍは１〜２の整数であり、ｍが１の場合、Ｒ_１は炭素数１〜４の炭化水素基、ｍが２の場合、Ｒ_１は水素原子を表す。＊は炭化水素基に結合する結合手を示す。）
（２）前記重合体（Ｐ）が、更に、熱脱離性基で保護されたアミノ基を有する上記（１）に記載の液晶配向剤。
（３）前記重合体（Ｐ）が、ポリイミド前駆体及び該ポリイミド前駆体をイミド化したポリイミドからなる群より選ばれる少なくとも一種の重合体である上記（１）又は（２）に記載の液晶配向剤。
（４）前記ポリイミド前駆体が、前記式（Ｉ−１）又は（Ｉ−２）で表される部分構造、及び熱脱離性基で保護されたアミノ基を有するジアミンを用いて得られる重合体である上記（１）〜（３）のいずれかに記載の液晶配向剤。
（５）前記ジアミンが、下記式（II−１）〜（II−３）で表されるジアミンから選ばれる少なくとも１種である上記（４）に記載の液晶配向剤。

（Ｌ、Ｍは、２価の有機基であり、Ｑは３価の有機基であり、ｎは０〜２の整数を表す。Ｐは、前記式（Ｉ−１）又は式（Ｉ−２）で表される構造を表し、Ｐ_２は熱脱離性基で保護されたアミノ基を表す。）
（６）前記式（II−１）〜（II−３）中、Ｌ、Ｍが、炭素数１〜１１を有するアルキレン基、２価の脂肪族環構造又は２価の芳香族環構造を表す。アルキレン基の任意の−ＣＨ_２−はそれぞれが隣り合わない組み合わせで−Ｏ−、−ＣＯＯ−又は−Ｓｉ−Ｏ−Ｓｉ−で置換されていてもよい。下記に示す環構造に置換されていてもよい。Ｒ_２は炭素原１〜５の炭化水素基を表す。

（７）前記ポリイミド前駆体が、さらに、下記式［Ｓ１］〜［Ｓ３］からなる群から選ばれる側鎖構造を有するジアミンを用いて得られる重合体である上記（４）〜（６）のいずれかに記載の液晶配向剤。

（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、ｍ_１は１〜２である。Ｇ^１及びＧ^２はそれぞれ独立して、炭素数６〜１２の２価の芳香族基又は炭素数３〜８の２価の脂環式基から選ばれる２価の環状基を表す。前記環状基上の任意の水素原子は、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシル基、炭素数１〜３のフッ素含有アルキル基、炭素数１〜３のフッ素含有アルコキシル基又はフッ素原子からなる群から選ばれる少なくとも１種で置換されていてもよい。ｍ及びｎはそれぞれ独立して０〜３の整数であって、ｍ及びｎの合計は１〜４である。Ｒ^１は炭素数１〜２０のアルキル、炭素数１〜２０のアルコキシ、又は炭素数２〜２０のアルコキシアルキルを表し、Ｒ^１を形成する任意の水素はフッ素で置換されていてもよい。）

（Ｘ^３は単結合、−ＣＯＮＨ−、−ＮＨＣＯ−、−ＣＯＮ（ＣＨ_３）−、−ＮＨ−、−Ｏ−、−ＣＨ_２Ｏ−、−ＣＯＯ−又は−ＯＣＯ−を表す。Ｒ^２は炭素数１〜２０のアルキル又は炭素数２〜２０のアルコキシアルキルを表し、Ｒ^２を形成する任意の水素はフッ素で置換されていてもよい。）

（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。
（８）前記熱脱離性基が、１５０〜３００℃で水素原子に置き換わる基である上記（１）〜（７）のいずれかに記載の液晶配向剤。
（９）前記熱脱離性基が、ｔ-ブトキシカルボニル基である上記（１）〜（８）のいずれかに記載の液晶配向剤。
（１０）上記（１）〜（９）のいずれかに記載の液晶配向剤から形成された液晶配向膜。
（１１）上記（１０）に記載の液晶配向膜を具備する液晶表示素子。That is, the present invention has the following gist.
(1) A liquid crystal alignment agent containing a polymer (P) having a partial structure represented by the following formula (I-1) or formula (I-2).

(A is a (n + 1) -valent hydrocarbon group having 1 to 18 carbon atoms, or a group having -O-, -COO-, -CO-, or -NHCO- between carbon-carbon bonds of the hydrocarbon group. S represents a single bond or a hydrocarbon group having 1 to 4 carbon atoms. P ₁ represents a hydroxyl group protected by a thermal desorption group. N is an integer of 1 to 5, and m is 1. It is an integer of ~ 2, and when m is 1, R ₁ represents a hydrocarbon group having 1 to 4 carbon atoms, and when m is 2, R ₁ represents a hydrogen atom. * Is a bond bond to a hydrocarbon group. Shows.)
(2) The liquid crystal alignment agent according to (1) above, wherein the polymer (P) further has an amino group protected by a thermal desorption group.
(3) The liquid crystal orientation according to (1) or (2) above, wherein the polymer (P) is at least one polymer selected from the group consisting of a polyimide precursor and a polyimide obtained by imidizing the polyimide precursor. Agent.
(4) A weight obtained by using a diamine in which the polyimide precursor has a partial structure represented by the formula (I-1) or (I-2) and an amino group protected by a thermal desorption group. The liquid crystal alignment agent according to any one of (1) to (3) above, which is a coalescence.
(5) The liquid crystal alignment agent according to (4) above, wherein the diamine is at least one selected from diamines represented by the following formulas (II-1) to (II-3).

(L and M are divalent organic groups, Q is a trivalent organic group, and n represents an integer of 0 to 2. P represents the above formula (I-1) or formula (I-2). represents a structure represented by), P ₂ represents an amino group protected with heat leaving group.)
(6) In the formulas (II-1) to (II-3), L and M represent an alkylene group having 1 to 11 carbon atoms, a divalent aliphatic ring structure or a divalent aromatic ring structure. .. _{Any −CH 2−} of the alkylene group may be substituted with −O−, −COO− or −Si—O—Si− in a non-adjacent combination. It may be replaced with the ring structure shown below. R ₂ represents a hydrocarbon group of carbon sources 1-5.

(7) The above-mentioned (4) to (6), wherein the polyimide precursor is a polymer obtained by using a diamine having a side chain structure selected from the group consisting of the following formulas [S1] to [S3]. The liquid crystal alignment agent according to any one.

(X ¹ and X ² are independent, single bond,-(CH ₂ ) _a- (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON (CH ₃ )-, It represents −NH−, −O−, −COO−, −OCO− or − ((CH ₂ ) _a1 −A ₁ ) _m1 −. Of these, a plurality of a1s are independently integers of 1 to 15. , a plurality of _{a 1} represents an oxygen atom or -COO- independently, _{m 1} is .G ¹ and ^{G 2} is a 1-2 are each independently a divalent aromatic having 6 to 12 carbon atoms Represents a divalent cyclic group selected from a group or a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group is an alkyl group having 1 to 3 carbon atoms and 1 to 1 carbon atoms. M and n may be substituted with at least one selected from the group consisting of an alkoxyl group of 3, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxyl group having 1 to 3 carbon atoms, or a fluorine atom. They are independently integers of 0 to 3, and the sum of m and n is 1 to 4. R ¹ is an alkyl having 1 to 20 carbon atoms, an alkoxy having 1 to 20 carbon atoms, or 2 to 20 carbon atoms. Any hydrogen representing the alkoxyalkyl of the above ^{and forming R 1} may be substituted with fluorine.)

(X ³ represents a single bond, _{-CONH-, -NHCO-, -CON (CH 3} )-, _{-NH-, -O-, -CH 2} O-, -COO- or -OCO-. R ^{2 represents.} Any hydrogen representing an alkyl having 1 to 20 carbon atoms or an alkoxyalkyl having 2 to 20 carbon atoms ^{and forming R 2} may be substituted with fluorine.)

(X ⁴ represents -CONH-, -NHCO-, -O-, -COO- or -OCO-. R ³ represents a structure having a steroid skeleton.
(8) The liquid crystal alignment agent according to any one of (1) to (7) above, wherein the thermally desorbing group is a group that replaces a hydrogen atom at 150 to 300 ° C.
(9) The liquid crystal alignment agent according to any one of (1) to (8) above, wherein the thermoremovable group is a t-butoxycarbonyl group.
(10) A liquid crystal alignment film formed from the liquid crystal alignment agent according to any one of (1) to (9) above.
(11) A liquid crystal display element including the liquid crystal alignment film according to (10) above.

According to the present invention, a liquid crystal alignment film having good adhesion to a substrate for a long period of time can be obtained even under high temperature and high humidity, and by using the liquid crystal alignment agent of the present invention, voltage holding characteristics for a long period of time can be obtained. A liquid crystal display element having excellent resistance to high temperature and high humidity can be obtained. Further, it is possible to provide a liquid crystal display element showing good vertical orientation even when an excessive firing process is added.

上記式（１−１）、式（１−２）における、Ａ、Ｓ、Ｒ_１、Ｐ_１、ｎ、ｍ、＊の定義は上記したとおりである。[Polymer (P)]
The liquid crystal alignment agent of the present invention contains a polymer having a partial structure represented by the following formula (I-1) or formula (I-2) (also referred to as a polymer (P) in the present invention).

_{The definitions of A, S, R 1} , P ₁ , n, m, and * in the above formulas (1-1) and (1-2) are as described above.

Further, P ₁ is preferably a thermally desorbable group that is desorbed at 150 to 300 ° C., particularly preferably 180 to 250 ° C. and replaced with hydrogen. Preferred specific examples are a t-butoxycarbonyl group, a benzyloxycarbonyl group, a 9-fluorenylmethyloxycarbonyl group, an allyloxycarbonyl group, or represented by the following formulas (t-1) to (t-8). Group is mentioned. In the following equation, * indicates a bond with an oxygen atom.

Among them, P ₁ is preferably a t-butoxycarbonyl group (Boc group), a benzyloxycarbonyl group, a 9-fluorenylmethyloxycarbonyl group, or an allyloxycarbonyl group because of its high heat-removability. More preferably, it is a t-butoxycarbonyl group or a 9-fluorenylmethyloxycarbonyl group.

The polymer (P) preferably further has an amino group protected by a thermal desorption group. When it has an amino group protected by such a heat-removable group, the resistance to high temperature and high humidity of the obtained liquid crystal alignment film can be further enhanced.
The thermally desorbable group that protects such an amino group is a thermally desorbable group that is desorbed by heat and replaced with hydrogen, and among them, preferably replaced with hydrogen at 150 to 300 ° C., particularly preferably 180 to 250 ° C. Thermoremovable groups are preferred. A preferred specific example thereof is the same as the above-mentioned thermal desorption group that protects a hydroxyl group.
_{Among them, P 1} is preferably a t-butoxycarbonyl group (Boc group), a benzyloxycarbonyl group, a 9-fluorenylmethyloxycarbonyl group, or an allyloxycarbonyl group because of its high thermal desorption. More preferably, it is a t-butoxycarbonyl group or a 9-fluorenylmethyloxycarbonyl group.

The main skeleton of the polymer (P) is not particularly limited, and for example, a polyimide precursor, a polyimide, a polysiloxane, a polyester, a polyamide, a cellulose derivative, a polyacetal, a polystyrene derivative, a poly (styrene-phenylmaleimide) derivative, and a poly (meth). ) The main skeleton such as acrylate can be mentioned. In addition, (meth) acrylate means containing acrylate and methacrylate. Examples of the polyimide precursor include polyamic and polyamic acid esters. The polymer (P) may be used alone or in combination of two or more.

The polymer (P) is preferably at least one selected from the group consisting of polyimide precursors, polyimides, polyamides, polyorganosiloxanes, poly (meth) acrylates and polyesters, and is more preferably than polyimide precursors and polyimides. More preferably, it is at least one polymer selected from the above group.

[Specific diamine]
The polyimide precursor and / or polyimide, which is the polymer (P), was protected by a partial structure represented by the above formula (I-1) or (I-2), and preferably a thermally desorbing group. It is obtained by using a diamine having an amino group (also referred to as a specific diamine in the present invention).
In the present invention, by using a specific diamine, a liquid crystal alignment film having a high vertical alignment ability that exhibits a stable pretilt angle even in a harsh device manufacturing process can be obtained, but the mechanism is not clear. However, it is assumed that the specific diamine is deprotected by heating and a hydroxy group is generated. It is generally known that a hydroxy group causes a cross-linking reaction with a carboxylic acid existing in polyimide, and this reaction is widely used in an actual cross-linking agent or the like. By using the specific diamine of the present invention, the cross-linking reaction of the polyimide-based polymer proceeds from the deprotection reaction by heating, and the polymer and the side chain structure having vertical orientation ability are stabilized. It is considered that the orientation is less likely to decrease.

The specific diamine is preferably at least one selected from the group consisting of the following formulas (II-1) to (II-3).

In the above formulas (II-1) to (II-3), L and M are divalent organic groups, Q is a trivalent organic group, and n represents an integer of 0 to 2. P represents a structure represented by the above formula (I-1) or formula (I-2), and P ₂ represents an amino group protected by a thermoremovable group.
Among them, L and M each independently represent an alkylene group having 1 to 11 carbon atoms, a divalent aliphatic ring structure, or a divalent aromatic ring structure. Any of the alkylene groups −CH ₂₋ may be substituted with −O−, −COO− or −Si—O—Si− in a non-adjacent combination. It may be replaced with the ring structure shown below. R ₂ represents a hydrocarbon group of carbon sources 1-5.

Specific examples of the diamine for producing the polymer (P) include the following formulas [M-1] to [M-34]. The diamine may be used alone or in combination of two or more.

[Tetracarboxylic acid component]
The polyamic acid, which is a polyimide precursor as the polymer (P), can be obtained by subjecting the specific diamine to a polycarboxylic acid component in a polycondensation reaction.
Examples of the tetracarboxylic acid component include tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, and tetracarboxylic acid dialkyl ester dihalide.

Examples of the tetracarboxylic dianhydride include aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aromatic tetracarboxylic dianhydride. Specific examples of these include each of the following groups [1] to [5].

[1] Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride.
[2] As the alicyclic tetracarboxylic dianhydride, for example, an acid dianhydride having the following formulas (X1-1) to (X1-13).

In the above formulas (X1-1) to (X1-4), R _{3 to} R ₂₃ are independently hydrogen atoms, halogen atoms, alkyl groups having 1 to 6 carbon atoms, and alkenyl groups having 2 to 6 carbon atoms. It represents an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. _RM represents a hydrogen atom or a methyl group. Further, in the above formula (X1-13), Xa represents a tetravalent organic group represented by the following formulas (Xa-1) to (Xa-7).

[3] 3-Oxabicyclo [3.2.1] Octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2', 5'-dione), 3,5,6-tricarboxy- 2-carboxymethyl norbornane-2: 3,5: 6-dianhydride, 4,9-dioxatricyclo [5.3.1.02,6] undecane-3,5,8,10-tetraone and the like.

[4] As the aromatic tetracarboxylic dianhydride, for example, pyromellitic dianhydride, 4,4'-(hexafluoroisopropyridene) diphthalic anhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride. Acid dianhydrides, acid dianhydrides represented by the following formulas (Xb-1) to (Xb-10), and the following (Xb-1) to (Xb-10).

[5] Acid dianhydrides represented by the following formulas (X1-44) to (X1-52), tetracarboxylic dianhydrides described in Japanese Patent Application Laid-Open No. 2010-97188, and the like.

The above tetracarboxylic acid component can be used alone or in combination of two or more. Depending on the characteristics required for the liquid crystal alignment film and the liquid crystal display element, one type alone or two or more types can be mixed and used, and when two or more types are mixed and used, the ratio can be appropriately adjusted.

(Other diamines)
As the diamine used for producing the polymer (P), in addition to the specific diamine, a side chain structure selected from the group represented by the following formulas [S1] to [S3] (hereinafter, also referred to as a specific side chain structure). ); A diamine having a function of generating a polymer or a radical by irradiation with light; a diamine described in paragraph 0169 of WO2015 / 046374, a diamine having a carboxyl group or a hydroxyl group according to paragraphs 0171 to 0172, a paragraph. Diamines having a nitrogen-containing heterocycle described in 0173 to 0188 and diamines having a nitrogen-containing structure described in paragraph 0050 of Japanese Patent Application Laid-Open No. 2016-218149, 1,3-bis (3-aminopropyl) -1,1 , 3,3-Tetramethyldisiloxane, 1,3-bis (4-aminobutyl) -1,1,3,3-tetramethyldisiloxane and other organosiloxane-containing diamines. A polymer using a diamine having a specific side chain structure as at least a part of the raw material is suitable from the viewpoint of increasing the heat resistance of the liquid crystal alignment film. Further, a polymer using a carboxyl group-containing diamine as at least a part of the raw material is preferable in that the effect of improving the coatability (printability) of the liquid crystal alignment agent can be enhanced.

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、ｍ_１は１〜２である。Ｇ^１及びＧ^２はそれぞれ独立して、炭素数６〜１２の２価の芳香族基又は炭素数３〜８の２価の脂環式基から選ばれる２価の環状基を表す。前記環状基上の任意の水素原子は、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシル基、炭素数１〜３のフッ素含有アルキル基、炭素数１〜３のフッ素含有アルコキシル基又はフッ素原子からなる群から選ばれる少なくとも１種で置換されていてもよい。ｍ及びｎはそれぞれ独立して０〜３の整数であって、ｍ及びｎの合計は１〜４である。Ｒ^１は炭素数１〜２０のアルキル、炭素数１〜２０のアルコキシ、又は炭素数２〜２０のアルコキシアルキルを表し、Ｒ^１を形成する任意の水素はフッ素で置換されていてもよい。

In the formula [S1], X ¹ and X ² are independently single-bonded, − (CH ₂ ) _a − (a is an integer of 1 to 15), −CONH−, −NHCO−, −CON ( CH ₃ )-, -NH-, -O-, -COO-, -OCO- or-((CH ₂ ) _a1- A ₁ ) _m1- . Among them, the plurality of a1 are each independently 1 to 15 integer, each independently plurality of _{A 1} represents an oxygen atom or -COO-, _{m 1} is 1 to 2. G ¹ and G ² each independently represent a divalent cyclic group selected from a divalent aromatic group having 6 to 12 carbon atoms or a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group may be an alkyl group having 1 to 3 carbon atoms, an alkoxyl group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, or a fluorine-containing alkoxyl group having 1 to 3 carbon atoms. Alternatively, it may be substituted with at least one selected from the group consisting of fluorine atoms. m and n are independently integers of 0 to 3, and the sum of m and n is 1 to 4. R ¹ represents an alkyl having 1 to 20 carbon atoms, an alkoxy having 1 to 20 carbon atoms, or an alkoxy alkyl having 2 to 20 carbon atoms, and ^{any hydrogen forming R 1} may be substituted with fluorine.

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。Ｒ^２は炭素数１〜２０のアルキル又は炭素数２〜２０のアルコキシアルキルを表し、Ｒ^２を形成する任意の水素はフッ素で置換されていてもよい。

In formula [S2], X ³ is a single bond, _{-CONH-, -NHCO-, -CON (CH 3} )-, _{-NH-, -O-, -CH 2} O-, -COO- or -OCO-. Represent. R ² represents an alkyl having 1 to 20 carbon atoms or an alkoxy alkyl having 2 to 20 carbon atoms, and ^{any hydrogen forming R 2} may be substituted with fluorine.

（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。

(In the formula [S3], X ⁴ represents -CONH-, -NHCO-, -O-, -COO- or -OCO-. R ³ represents a structure having a steroid skeleton.

Examples of the diamine having a specific side chain structure include diamines represented by the following formula [1] or formula [2]. In addition, these can be used individually by 1 type or in combination of 2 or more types.

In the above formula [2], X is a single bond, -O-, -C (CH ₃ ) _2- , -NH-, -CO-,-(CH ₂ ) _m- , -SO _2- , -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-, or -COO- represents a _{(CH 2)} m -OCO- ₂ monovalent organic group. m is an integer of 1-8. Y represents the side chain structure represented by the above formulas [S1] to [S3].

As a preferable specific example of the formula [S1], the structures of the following formulas [S1-x1] to [S1-x7] can be mentioned.

In the above formula, R ¹ is an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. X ^p is − (CH ₂ ) _a − (a is an integer of 1 to 15), −CONH−, −NHCO−, −CON (CH ₃ ) −, _{−NH−, −O−, −CH 2} O-, -CH ₂ OCO-, -COO-, or -OCO-. A ₁ is an oxygen atom or -COO- * (however, the bond with "*" binds to (CH ₂ ) _a2 ), and A ₂ is an oxygen atom * -COO- (however, "*"). a given binding hands _{(CH 2)} binds to _a2), a 1, _{a 3} are each independently an integer of 01, _{a 2} represents an integer of 1 to 10, Cy is 1, 4-Cyclohexylene group 1,4-phenylene group.

A preferred specific example of the above formula [S3] is the following formula [S3-x].

（ｎは１〜２０の整数を示す。）Specific examples of the diamine of the above formula [1] include the following formulas [S-1] to [S-18].

(N indicates an integer of 1 to 20.)

Examples of the diamine represented by the above formula [2] include a structure selected from the group consisting of the following formulas [W-1] to [W-6].

In the above formula, X ^{p1 to} X ^p8 are independently − (CH ₂ ) _a − (a is an integer of 1 to 15), −CONH−, −NHCO−, −CON (CH ₃ ) −. , -NH- _{, -O-, -CH 2} O-, -CH ₂ OCO-, -COO-, or -OCO-, and X ^{s1 to} X ^s4 are independently -O-, -COO-, respectively. Alternatively, -OCO- is indicated, X _{a to} X _f indicate -O-, -NH-, and -O- (CH ₂ ) _m- O-, and R ^{1a to} R ^1h are independent of each other and have 1 carbon atom. Alkyl groups of ~ 20 and alkoxy groups having 1 to 20 carbon atoms are shown as alkoxyalkyl groups having 2 to 20 carbon atoms. m represents an integer of 1-8.
The diamine having a specific side chain structure is preferably 1 mol% or more, more preferably 2 mol% or more, based on the specific diamine. Further, it is preferably 90 mol% or less, and more preferably 85 mol% or less.

Examples of the diamine having a function of polymerizing by light irradiation include diamines in which the structures represented by the following formulas [p1] to [p7] are directly bonded to an aromatic ring such as a benzene ring via a linking group. be able to.

式［Ｐ_ａ］、式［Ｐ_ｂ］における２つのアミノ基（−ＮＨ_２）の結合位置は、反応性の観点から、２，４位の位置、２，５位の位置、又は３，５位の位置が好ましい。ジアミンを合成する際の容易性も加味すると、２，４位の位置、又は３，５位の位置がより好ましい。Specific examples include a diamine represented by the following formula _{[P a]} or _{[P b].}

_{From the viewpoint of reactivity, the bonding positions of the two} amino groups (-NH 2) in the formulas [P _a ] and [P _b ] are the positions of the 2, 4 position, the 2, 5 position, or the 3, 5 position. The position of the position is preferable. Considering the ease of synthesizing the diamine, the positions at the 2nd and 4th positions or the 3rd and 5th positions are more preferable.

Wherein _{[P a],} ^{R 8} represents a single bond, -O -, - COO -, - OCO -, - NHCO -, - CONH -, - NH -, - CH 2 O -, - N (CH 3) Represents −, −CON (CH ₃ ) −, or −N (CH ₃ ) CO−, and is single bond, −O−, −COO−, −NHCO−, or −CONH− due to ease of manufacture. Is preferable.

R ⁹ is a divalent group selected from a single bond, an alkylene group having 1 to 20 carbon atoms which may be substituted with a fluorine atom, an aromatic ring having 6 to 12 carbon atoms such as a benzene ring and a naphthalene ring, and cyclohexane. A divalent alicyclic group having 3 to 8 carbon atoms such as a ring, a 5-membered ring such as pyrrol, imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, indol, quinoline, carbazole, thiazole, purine, tetrahydrofuran, thiophene, etc. Represents a divalent cyclic group selected from the heterocycles of. _{Here, −CH 2} − of the alkylene group _{may be optionally substituted with −CF 2} − or −CH = CH −. From the viewpoint of ease of synthesis, a single bond or an alkylene group having 1 to 12 carbon atoms is preferable. k represents an integer from 0 to 4.
R ¹⁰ represents a structure selected from the above formulas [p1] to [p7]. From the viewpoint of photoreactivity, [p1], [p2], and [p4] are preferable.

In the formula [P _b ], Y ₁ and Y ₃ are independently -CH _2- , -O-, -CONH-, -NHCO-, -COO-, -OCO-, -NH-, or-. Represents CO-. Y ₂ and Y ₅ are independently synonymous with _{R 9} in the above [PA]. Y ₄ represents a cinnamoyl group. Y ₆ represents a structure selected from the above formulas [p1] to [p7]. From the viewpoint of photoreactivity, [p1], [p2], and [p4] are preferable. m represents 0 or 1.

Diamine, which has a function of polymerizing by light irradiation, depends on the liquid crystal orientation when it is used as a liquid crystal alignment film, pretilt angle, voltage holding characteristics, characteristics such as accumulated charge, and the response speed of the liquid crystal when it is used as a liquid crystal display element. One type or a mixture of two or more types can be used.

The diamine having a function of polymerizing by light irradiation is preferably 1 mol% or more, more preferably 2 mol% or more, based on the total amount of diamine used for the synthesis of the polymer (P). Further, the upper limit of the usage ratio can be arbitrarily set within the range of 100 mol% or less. It is preferably 90 mol% or less, and more preferably 85 mol% or less.

Examples of the diamine having a function of generating radicals by light irradiation include diamines having a site having a radical generation structure that decomposes by ultraviolet irradiation and generates radicals in a side chain. For example, a diamine represented by the following formula [R] is used. Can be mentioned.

_{Ar, R 1} , R ₂ , T ₁ , T ₂ , S and Q in the above formula [R] have the following definitions.
That is, Ar represents an aromatic hydrocarbon group selected from phenylene, naphthylene, and biphenylene, which may be substituted with an organic group and a hydrogen atom may be substituted with a halogen atom. R ₁ and R ₂ are independently alkyl groups or alkoxy groups having 1 to 10 carbon atoms.
T ₁ and T ₂ are independently single-bonded or -O-, -COO-, -OCO-, -NHCO-, -CONH-, -NH-, -CH ₂ O-, -N (CH ₃ ). -, -CON (CH ₃ )-, -N (CH ₃ ) CO- binding group.

S in the formula [R] has the same meaning as ^{R 9} in the above _{[P a].}
Q is a structure selected from the following formulas [q-1] to [q-4] (R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ₃ is −CH ₂ −, −NR−, − Represents O- or -S-).

（式中、＊は結合位置を示す。）

(In the formula, * indicates the bonding position.)

In the above formula [R], Ar having a carbonyl bond is preferably a structure having a long conjugated length such as naphthalene or biphenylene from the viewpoint of efficient absorption of ultraviolet rays. Further, Ar may be substituted with a substituent, and the substituent is preferably an electron-donating organic group such as an alkyl group, a hydroxyl group, an alkoxy group or an amino group. When the wavelength of ultraviolet rays is in the range of 250 nm to 380 nm, a phenyl group is most preferable because sufficient characteristics can be obtained even with a phenyl group.
Further, R ₁ and R ₂ are independently alkyl groups having 1 to 10 carbon atoms, an alkoxy group, a benzyl group, or a phenethyl group, and in the case of an alkyl group or an alkoxy group, the rings are ringed with _{R 1} and R _2. May be formed.
Q is more preferably a hydroxyl group or an alkoxyl group.

The diaminobenzene in the formula (R) may have any structure of o-phenylenediamine, m-phenylenediamine, or p-phenylenediamine, but m-phenylenediamine, in that it has high reactivity with the tetracarboxylic acid component, Alternatively, p-phenylenediamine is preferable.
Specifically, the structures represented by the following formulas [R-1] to [R-4] are most preferable from the viewpoints of ease of synthesis, high versatility, characteristics and the like. In the formula, n is an integer of 2 to 8.

The diamine having a function of generating radicals by light irradiation is preferably 1 mol% or more, more preferably 2 mol% or more, based on the total amount of diamine used for the synthesis of the polymer (P). It is more preferably 5 mol% or more. Further, the upper limit of the usage ratio can be arbitrarily set within the range of 100 mol% or less. It is preferably 70 mol% or less, more preferably 60 mol% or less, and further preferably 50 mol% or less.

Preferred specific examples of the diamine having the specific side chain structure or other diamines other than the diamine having the function of generating polymerization or radicals by light irradiation are m-phenylenediamine, p-phenylenediamine, and 4,4'-diaminobiphenyl. , 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4 '-Diaminodiphenylamine, N-methyl (4,4'-diaminodiphenyl) amine, 4,4'-diaminobenzophenone, 1,4-diaminonaphthalene, 2,6-diaminonaphthalene, 1,2-bis (4-amino) Phenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,4-bis (4-aminophenyl) butane, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (4) -Aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (4-aminobenzyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 4,4'- [1,4-Phenylenebis (methylene)] dianiline, 1,4-phenylenebis [(4-aminophenyl) metanone], 1,4-phenylenebis (4-aminobenzoate), bis (4-aminophenyl) terephthalate , Bis (4-aminophenyl) isophthalate, N, N'-(1,4-phenylene) bis (4-aminobenzamide), N, N'-bis (4-aminophenyl) terephthalamide, N, N' -Bis (4-aminophenyl) isophthalamide, 9,10-bis (4-aminophenyl) anthracene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-bis ( 4-aminophenyl) propane, 1,3-bis (4-aminophenoxy) propane, 1,4-bis (4-aminophenoxy) butane, 1,5-bis (4-aminophenoxy) pentane, 1,6- Bis (4-aminophenoxy) hexane, 1,7-bis (4-aminophenoxy) heptane, 1,8-bis (4-aminophenoxy) octane, 1,9-bis (4-aminophenoxy) nonane, 1 , 10- (4-aminophenoxy) decane, bis (4-aminocyclohexyl) methane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diamino Xan, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, 4,4'-diaminobiphenyl-3-carboxylic acid, 4,4'-diaminodiphenylmethane-3-carboxylic acid Acid, 4,4'-diaminodiphenylethane-3-carboxylic acid, 4,4'-diaminobiphenyl-3,3'-dicarboxylic acid, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 3, 3'-diaminobiphenyl-4,4'-dicarboxylic acid, 3,3'-diaminobiphenyl-2,4'-dicarboxylic acid, 4,4'-diaminodiphenylmethane-3,3'-dicarboxylic acid, 4,4' -Diaminodiphenylethane-3,3'-dicarboxylic acid, 4,4'-diaminodiphenyl ether-3,3'-dicarboxylic acid, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis- (4-aminophenyl) -piperazin, 3,6-diaminoaclydin, N-ethyl-3,6-diaminocarbazole , N-phenyl-3,6-diaminocarbazole, N, N'-bis (4-aminophenyl) -benzidine, N, N'-bis (4-aminophenyl) -N, N'-dimethylbenzidine, formula below Examples thereof include compounds represented by each of the formulas (D-2-1) to (D-2-8).

(Manufacturing of polyamic acid)
The polyamic acid is usually produced by mixing a diamine and a tetracarboxylic acid compound in a solvent. The solvent is not particularly limited as long as the produced polymer dissolves.

Specific examples of the above solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, and dimethyl sulfoxide 1,3-dimethyl-2. -Imidazolidinone can be mentioned. When the polymer has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the following formulas [D-1] to [D-3] can be used. The indicated solvents can be used.

（式［Ｄ−１］中、Ｄ^１は炭素数１〜３のアルキレン基を示し、式［Ｄ−２］中、Ｄ^２は炭素数１〜３のアルキレン基を示し、式［Ｄ−３］中、Ｄ^３は炭素数１〜４のアルキレン基を示す）。

(In the formula [D-1], D ¹ represents an alkylene group having 1 to 3 carbon atoms, and in the formula [D-2], D ² represents an alkylene group having 1 to 3 carbon atoms, and the formula [D-3]. during], ^{D 3} represents an alkylene group having 1 to 4 carbon atoms).

These solvents may be used alone or in combination. Further, even if the solvent does not dissolve the polymer, it may be mixed with the above solvent and used as long as the produced polymer does not precipitate. Further, since the water content in the solvent inhibits the polymerization reaction and further causes the produced polymer to be hydrolyzed, it is preferable to use a dehydrated and dried solvent.

When the diamine and the tetracarboxylic dian compound are reacted in a solvent, the reaction can be carried out at an arbitrary concentration, but if the concentration is too low, it becomes difficult to obtain a high-molecular-weight polymer, and the concentration is too high. The viscosity of the reaction solution becomes too high, and uniform stirring becomes difficult. Therefore, it is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The initial reaction can be carried out at a high concentration and then the solvent can be added.
In the polymerization reaction of the polymer (P), the ratio of the total number of moles of the diamine to the total number of moles of the tetracarboxylic dian compound is preferably 0.8 to 1.2. Similar to a normal polycondensation reaction, the closer the molar ratio is to 1.0, the larger the molecular weight of the specific polymer produced.

[Polyamic acid ester]
The polyamic acid ester which is a polyimide precursor is, for example, [I] a method of reacting a polyamic acid obtained by the above synthesis reaction with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine, [II] a method of reacting a tetracarboxylic acid diester with a diamine. III] It can be obtained by a known method such as a method of reacting a tetracarboxylic acid diester dihalide with a diamine.

[Polyimide]
The polyimide is a polyimide obtained by ring-closing the above-mentioned polyimide precursor, and 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%, depending on the application and purpose. It can be adjusted arbitrarily.
Examples of the method for imidizing the polyimide precursor include catalytic imidization in which a catalyst is added to the solution of the thermally imidized polyimide precursor in which the solution of the polyimide precursor is heated as it is.
The temperature at which the polyimide precursor is thermally imidized in the solution is 100 ° C. to 400 ° C., preferably 120 ° C. to 250 ° C., and it is preferable to remove the water generated by the imidization reaction from the outside of the system.

The catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to the solution of the polyimide precursor and stirring at −20 ° C. to 250 ° C., preferably 0 ° C. to 180 ° C. it can. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times, that of the amic acid group, and the amount of acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times that of the amic acid group. It is double. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, and tributylamine trioctylamine. Among them, pyridine is preferable because it has an appropriate basicity for advancing the reaction. Examples of the acid anhydride include acetic anhydride and trimellitic anhydride pyromellitic anhydride. Among them, acetic anhydride is preferable because it facilitates purification after completion of the reaction. The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, the reaction temperature, and the reaction time.

Polyimide precursor When recovering the produced polyimide precursor polyimide from the reaction solution of polyimide, the reaction solution may be added to a solvent to precipitate. Examples of the solvent used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellsolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, water and the like. The polymer which has been put into a solvent and precipitated can be collected by filtration and then dried at normal temperature or by heating under normal pressure or reduced pressure. Further, if the operation of redistributing the polymer recovered by precipitation in a solvent and reprecipitating and recovering the polymer is repeated 2 to 10 times, impurities in the polymer can be reduced. Examples of the solvent at this time include alcohols, ketones hydrocarbons, and the like, and it is preferable to use three or more kinds of solvents selected from these because the purification efficiency is further improved.

The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the polyimide precursor and the polyimide 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 15 or less, more preferably 10 or less. Within such a molecular weight range, good orientation of the liquid crystal display element can be ensured.

When the liquid crystal alignment agent of the present invention contains a polymer (P), for example, for the purpose of improving electrical properties and solution properties, the polymer (P) and other polymers (hereinafter, other weights) are used together with the polymer (P). It may also contain (also referred to as coalescence). In this case, the ratio of other polymers used is preferably 80 parts by mass or less, preferably 0.1 to 80 parts by mass, based on 100 parts by mass of the total amount of the polymers contained in the liquid crystal alignment agent. Is more preferable, and 0.3 to 70 parts by mass is further preferable.

The main skeleton of other polymers is not particularly limited, and for example, polyimide precursor, polyimide, polysiloxane, polyester, polyamide, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene-phenylmaleimide) derivative, poly (meth) acrylate and the like. The main skeleton of. Among them, at least one selected from the group consisting of polyimide precursor, polyimide, polyamide, polyorganosiloxane, poly (meth) acrylate and polyester is preferable, and it is selected from the group consisting of polyimide precursor, polyimide and polysiloxane. It is more preferable that it is at least one kind. The other polymers may be used alone or in combination of two or more.

The liquid crystal alignment agent of the present invention may contain other components other than the above, if necessary. Examples of the component include a compound having at least one epoxy group in the molecule, a compound having at least one oxetanyl group in the molecule, a functional silane compound, a metal chelate compound, a curing accelerator, a surfactant, and an antioxidant. , Sensitizers, preservatives and the like.

<Solvent>
The liquid crystal alignment agent of the present invention is prepared as a liquid composition in which the polymer (P) and other components used as needed are preferably dispersed or dissolved in a suitable solvent.

Examples of the organic solvent used include N-methyl-2-pyrrolidone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, and the like. γ-Butylollactone, γ-Butylolactam, N, N-dimethylformamide, N, N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methylmethoxypropione- Eth, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol mono Butyl ether ether acetate, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl Examples thereof include ether, dipropylene glycol dimethyl ether, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, and propylene carbonate. These can be used alone or in admixture of two or more.

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. From the viewpoint of forming a uniform and defect-free coating film, 1% by mass or more is preferable, and from the viewpoint of storage stability of the solution, 10% by mass or less is preferable. A particularly preferable concentration of the polymer is 2 to 8% by mass.

<Liquid crystal alignment film / liquid crystal display element>
The liquid crystal alignment agent of the present invention can be used as a liquid crystal alignment film by applying it on a substrate, firing it, and then performing an alignment treatment by rubbing treatment, light irradiation, or the like. Further, in the case of vertical alignment applications, it can be used as a liquid crystal alignment film without alignment treatment. The substrate used at this time is not particularly limited as long as it is a highly transparent substrate, and in addition to the glass substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate can also be used. From the viewpoint of process simplification, it is preferable to use a substrate on which an ITO electrode or the like for driving a liquid crystal is formed. Further, in the reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used if only one substrate is used, and a material that reflects light such as aluminum can be used as the electrode in this case.

Examples of the method for applying the liquid crystal alignment agent include screen printing, offset printing, flexographic printing inkjet method, dip method, roll coater method, slit coater method, spinner method, and spray method. From the viewpoint of enhancing, a method of applying by flexographic printing or an inkjet method is preferable.

After applying the liquid crystal alignment agent on the substrate, it is dried at 40 to 150 ° C. by a heating means such as a hot plate or a heat circulation type oven IR (infrared) type oven, depending on the solvent used for the liquid crystal alignment agent. Then, the liquid crystal alignment film can be obtained by firing at a temperature of preferably 150 to 300 ° C., more preferably 180 to 250 ° C. Then, in such firing, the heat-removable group is desorbed from the hydroxyl group protected by the heat-removable group of the polymer (P) and the amino group protected by the heat-removable group, and each of them is desorbed. , Unprotected hydroxyl groups and amino groups are formed. It is considered that the generated hydroxyl groups and amino groups react with the carboxyl groups and amide groups of the polyimide precursor and polyimide to form a crosslinked structure. It is considered that the obtained liquid crystal alignment film thus brings about excellent high temperature and high humidity resistance and high voltage retention.
If the thickness of the liquid crystal alignment film after firing is too thick, it is disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the liquid crystal display element may decrease. Is 10 to 100 nm.

When the display mode of the manufactured liquid crystal display element is VA type, the coating film formed as described above can be used as it is as a liquid crystal alignment film, but if necessary, a rubbing treatment or PSA described later can be used. Processing may be performed. On the other hand, when the display mode of the manufactured liquid crystal display element is a vertical electric field method other than the VA type or a lateral electric field method, the formed coating film surface is subjected to rubbing treatment, polarized ultraviolet irradiation, or the like. The process is performed and the alignment process is performed.

The liquid crystal aligning agent of the present invention has a liquid crystal composition having a liquid crystal layer between a pair of substrates provided with electrodes, and contains a polymerizable compound that is polymerized by at least one of active energy rays and heat between the pair of substrates. It is also preferably used for a liquid crystal display element manufactured through a step of arranging an object and polymerizing a polymerizable compound by at least one of irradiation and heating of active energy rays while applying a voltage between electrodes. Here, the voltage to be applied can be, for example, a direct current or an alternating current of 5 to 50 V. Further, as the active energy ray, ultraviolet rays are suitable. The ultraviolet rays include ultraviolet rays having a wavelength of 300 to 400 nm, preferably ultraviolet rays having a wavelength of 310 to 360 nm. The irradiation amount of light is preferably 0.1 to 20 J / cm ² , and more preferably 1 to 20 J / cm ² .
The above-mentioned liquid crystal display element controls the pre-tilt of liquid crystal molecules by a PSA (Polymer Sustained Alignment) method. In the PSA method, a small amount of a photopolymerizable compound, for example, a photopolymerizable monomer is mixed in a liquid crystal material, a liquid crystal cell is assembled, and then an ultraviolet ray is applied to the photopolymerizable compound in a state where a predetermined voltage is applied to the liquid crystal layer. The pretilt of the liquid crystal molecules is controlled by the polymer produced by irradiating the liquid crystal molecules. Since the orientation state of the liquid crystal molecules when the polymer is formed is memorized even after the voltage is removed, the pretilt of the liquid crystal molecules can be adjusted by controlling the electric field or the like formed in the liquid crystal layer. Further, since the PSA method does not require a rubbing process, it is suitable for forming a vertically oriented liquid crystal layer in which it is difficult to control the pre-tilt by the rubbing process.

The liquid crystal display element of the present invention is a liquid crystal display element obtained by obtaining a substrate with a liquid crystal alignment film from the liquid crystal alignment agent of the present invention by the above-mentioned method, and then producing a liquid crystal cell by a known method.
As a method for producing a liquid crystal cell, a pair of substrates on which a liquid crystal alignment film is formed is prepared, a spacer is sprayed on the liquid crystal alignment film of one substrate, the liquid crystal alignment film surface is on the inside, and the other is produced. Examples thereof include a method in which the substrates of the above are bonded and the liquid crystal is injected under reduced pressure to seal the liquid crystal, and a method in which the liquid crystal is dropped on the liquid crystal alignment film surface on which the spacer is sprayed and then the substrates are bonded and sealed.

As described above, the liquid crystal may be mixed with a polymerizable compound that polymerizes by ultraviolet irradiation or heat. The polymerizable compound is a compound having at least one polymerizable unsaturated group such as an acrylate group or a methacrylate group in the molecule, for example, a polymerizable compound represented by the following formulas (M-1) to (M-3). Compounds can be mentioned.

At that time, the content of the polymerizable compound is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the liquid crystal component. If the amount of the polymerizable compound is less than 0.01 parts by mass, the polymerizable compound does not polymerize and the orientation of the liquid crystal cannot be controlled. If the amount is more than 10 parts by mass, the number of unreacted polymerizable compounds increases and the liquid crystal display element. Seizure characteristics are reduced. After producing the liquid crystal cell, the polymerizable compound is polymerized by irradiating the liquid crystal cell with heat or ultraviolet rays while applying an AC / DC voltage to the liquid crystal cell. Thereby, the orientation of the liquid crystal molecules can be controlled.

The liquid crystal aligning agent of the present invention has a liquid crystal layer between a pair of substrates provided with electrodes, and contains a polymerizable group that polymerizes between the pair of substrates by at least one of active energy rays and heat. It may also be used in a liquid crystal display element manufactured through a step of arranging an alignment film and applying a voltage between electrodes, that is, in SC-PVA mode. Here, ultraviolet rays are suitable as the active energy rays. As the ultraviolet rays, the ultraviolet rays used in the PSA method can be applied including a preferable embodiment. In the case of polymerization by heating, the heating temperature is 40 to 120 ° C, preferably 60 to 80 ° C. Further, ultraviolet rays and heating may be performed at the same time.

In order to obtain a liquid crystal alignment film containing a polymerizable group that polymerizes from at least one of active energy rays and heat, a method of adding a compound containing this polymerizable group to a liquid crystal aligning agent or a polymer containing a polymerizable group A method using an ingredient can be mentioned. Specific examples of the polymer containing a polymerizable group include a polymer obtained by using a diamine having a function of polymerizing by the above-mentioned light irradiation.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. The abbreviations of the compounds and the method for evaluating the characteristics are as follows.

Boc ₂ O: di-tert-butyl dicarbonate, DMAP: dimethylaminopyridine NMP: N-methyl-2-pyrrolidone, BCS: butyl cellosolve

(Tetracarboxylic dianhydride)
BODA: Bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride (compound represented by the following formula "BODA")
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride (compound represented by the following formula "CBDA")
TCA: 2,3,5-tricarboxycyclopentyl acetate dianhydride (compound represented by the following formula "TCA")
PMDA: Pyromellitic anhydride (compound represented by the following formula "PMDA")

(Specific diamine)
DA-1: Compound represented by the following formula "DA-1" DA-2: Compound represented by the following formula "DA-2"

(Diamine with a specific side chain structure)
DA-3: 1,3-diamino-4- [4- (trans-4-n-heptylcyclohexyl) phenoxy] benzene DA-4: Diamine DA-5 having a specific side chain structure represented by the following formula: The following Diamine DA-6 having a specific side chain structure represented by the formula: Diamine having a specific side chain structure represented by the following formula

（添加剤）
３ＡＭＰ：３−ピコリルアミン(Other diamines)
DA-7 to DA-10 diamines represented by the following structure

(Additive)
3AMP: 3-picorylamine

<Number average molecular weight (Mn), weight average molecular weight (Mw) of polymer>
Using a room temperature gel permeation chromatography device (GPC, Senshu Kagaku Co., Ltd., SSC-7200) and a Shodex column (KD-803, KD-805), the eluent was N, N'-dimethylformamide (lithium bromide). -Hydrate (LiBr · H ₂ O) at 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) at 30 mmol / L, tetrahydrofuran at 10 ml / L), flow velocity 1.0 ml / min , Column temperature 50 ° C., Toso TSK standard polyethylene oxide (molecular weight about 9,000,000, 150,000, 100,000, 30,000) and Polymer Laboratory polyethylene glycol (molecular weight about 12,000, 4,000) , 1,000) was measured as a standard solution.

<Imidization rate>
20 mg of polyimide powder is placed in an NMR sample tube (NMR sampling tube standard φ5 manufactured by Kusano Kagaku Co., Ltd. _{), 1.0 ml of deuterated dimethyl sulfoxide (DMSO-d 6} , 0.05% TMS mixture) is added, and ultrasonic waves are applied. It was completely dissolved over. This solution was subjected to 500 MHz proton NMR measurement with an NMR measuring instrument (JNW-ECA500) manufactured by JEOL Datum. The imidization rate is determined by using a proton derived from a structure that does not change before and after imidization as a reference proton, and the peak integrated value of this proton and the proton peak derived from the NH group of the amic acid appearing in the vicinity of 9.5 to 10.0 ppm. It was calculated by the following formula using the integrated value.
Imidization rate (%) = (1-α · x / y) × 100
(In the formula, x is the integrated proton peak value derived from the NH group of the amic acid, y is the integrated peak value of the reference proton, and α is the proton 1 of the NH group of the amic acid in the case of polyamic acid (imidization rate is 0%). The ratio of the number of reference protons to the number of protons.

[Synthesis Example 1]: Synthesis of Compound 1

Under a nitrogen atmosphere, dimethylformamide (1100 g), 2- (2-aminoethylamino) -ethanol (45.3 g), 4-fluoronitrobenzene (126 g), and potassium carbonate (145 g) were added to a 4-neck flask, and 168 at room temperature. Stirred for hours. Then, the filtrate obtained by removing potassium carbonate by filtration was put into a dilute aqueous hydrochloric acid solution obtained by diluting 50 ml of concentrated hydrochloric acid with 2000 ml of water, and the precipitated compound 1 was filtered to obtain a crude product. The crude product was suspended in 750 ml of ethanol, stirred under reflux conditions for 2 hours, cooled to room temperature, filtered, and the cake was washed twice with 100 ml of ethanol. The obtained crystals were suspended in 1250 ml of tetrahydrofuran, stirred at 60 ° C. for 24 hours, cooled to room temperature, and then filtered. The obtained cake portion was washed twice with 100 ml of tetrahydrofuran and then dried to obtain 62.3 g (yield 41.4%) of compound 1.

窒素雰囲気下、４口フラスコに化合物１（２０．４ｇ）、ＤＭＡＰ（０．３６２ｇ）、ＮＭＰ（１７０ｇ）を入れ、Ｂｏｃ_２Ｏ（３０．１ｇ）をＮＭＰ３０ｍｌで希釈した混合溶液を室温下滴下した。室温で１７時間撹拌した後、水を２５０ｍｌ加え析出した化合物２をろ過し、得られたケーキ分を水１００ｍｌで４回洗浄し、乾燥させて化合物２を３０．１ｇ（収率９３．６％）で得た。[Synthesis Example 2]: Synthesis of Compound 2

Compound 1 (20.4 g), DMAP (0.362 g), and NMP (170 g) were placed in a four-necked flask under a nitrogen atmosphere, and a mixed solution of _{Boc 2 O (30.1 g) diluted with 30 ml of NMP was added dropwise at room temperature.} .. After stirring at room temperature for 17 hours, 250 ml of water was added and the precipitated compound 2 was filtered. The obtained cake was washed 4 times with 100 ml of water and dried to obtain 30.1 g of compound 2 (yield 93.6%). ).

窒素雰囲気下、４口フラスコに化合物２（３０．１ｇ）、５％パラジウムカーボン粉末５０％含水品（３．０１ｇ）、テトラヒドロフラン（２４０ｇ）を入れ、水素雰囲気に置換してから１２０時間室温常圧下撹拌した。反応終了後、０．４５μｍＰＴＦＥメンブレンフィルターでパラジウムカーボンをろ過し、得られたろ液を濃縮、乾燥させてＤＡ−１を２６．５ｇ（収率９９．０％）で得た。[Synthesis Example 3] Synthesis of compound (DA-1)

Under a nitrogen atmosphere, compound 2 (30.1 g), 5% palladium carbon powder 50% hydrous product (3.01 g), and tetrahydrofuran (240 g) were placed in a 4-neck flask, and the mixture was replaced with a hydrogen atmosphere for 120 hours at room temperature and normal pressure. Stirred. After completion of the reaction, palladium carbon was filtered through a 0.45 μm PTFE membrane filter, and the obtained filtrate was concentrated and dried to obtain 26.5 g (yield 99.0%) of DA-1.

The structure of compound (DA-1) was confirmed by obtaining the following spectral data by 1H-NMR measurement. For NMR measurement, JNW-ECA500 manufactured by JEOL Datum Co., Ltd. was used. ^{1 1} H-NMR (DMSO-d ₆ ): δ = 6.78-6.76 (br, 2H), 6.46 (t, 4H), 6.41 (t, 2H), 5.01 (s, 2H), 4.37 (s, 2H), 3.94 (t, 2H), 3.45 (t, 2H), 3.30-3.19 (br, 4H), 1.40-1.35 (Br, 18H).

[Synthesis Example 1]
BODA (3.38 g, 13.5 mmol), DA-1 (6.13 g, 12.6 mmol) and DA-3 (2.06 g, 5.4 mmol) were dissolved in NMP (46.2 g) at 80 ° C. CBDA (0.830 g, 4.23 mmol) and NMP (3.11 g) were added, and the mixture was reacted at 40 ° C. for 11 hours to obtain a polyamic acid solution.
NMP is added to this polyamic acid solution (40 g) to dilute it to 6.5% by mass, acetic anhydride (5.9 g) and pyridine (1.8 g) are added as imidization catalysts, and the mixture is reacted at 100 ° C. for 3 hours. It was. This reaction solution was put into methanol (560 ml), and the obtained precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 100 ° C. to obtain a polyimide powder (A). The imidization ratio of this polyimide was 72%, Mn was 17,000, and Mw was 132,000.

[Composite Comparison Example 1]
Polyimide powder (B) was obtained by carrying out in the same manner as in Synthesis Example 1 except that DA-2 was used instead of the diamine DA-1 used. The imidization ratio of this polyimide was 74%, Mn was 14,000, and Mw was 56,000.

[Synthesis Example 2] to [Synthesis Comparative Example 5]
Synthesis In the same manner as in Example 1, a polyamic acid solution and a polyimide powder were obtained using various tetracarboxylic acid components and diamine components. Table 1 shows the composition of the synthesized polymer.

The numerical values in Table 1 indicate the ratio (mol%) of the tetracarboxylic dianhydride used in the reaction to the total amount of the tetracarboxylic dianhydride used in the reaction, and for the diamine, the diamine component used in the reaction. Indicates the usage ratio (mol%).

<Preparation and evaluation of liquid crystal alignment agent>
[Example 1]
NMP (44.0 g) was added to the obtained polyimide powder (A) (6.0 g), and the mixture was dissolved by stirring at 80 ° C. for 17 hours. To this solution, a 6 mass% NMP diluted solution of 3AMP (1.0 g), NMP (9.0 g), and BCS (40.0 g) are added, and the mixture is stirred at room temperature for 5 hours to obtain a liquid crystal aligning agent (A1). It was.

(Manufacturing of PSA type liquid crystal display element)
Using the liquid crystal alignment agent (A1) obtained above, a liquid crystal display element was manufactured by the procedure shown below. The liquid crystal aligning agent (A1) is spin-coated on the ITO surface of an ITO electrode substrate having an ITO electrode pattern having a pixel size of 100 μm × 300 μm and a line / space of 5 μm, and dried on a hot plate at 80 ° C. for 90 seconds. After that, it was fired in an infrared heating furnace at 230 ° C. for 20 minutes to form a liquid crystal alignment film having a film thickness of 100 nm.
Further, as a harsh condition for evaluating the vertical orientation of the liquid crystal alignment film, a liquid crystal alignment film having a thickness of 100 nm was formed by firing in an infrared heating furnace at 230 ° C. for 60 minutes.

Using two of the above substrates, a bead spacer having a pore size of 4 μm was sprayed on the liquid crystal alignment film of one of the substrates, and then a sealant (solvent-type thermosetting epoxy resin) was printed on the bead spacers. Next, the surface of the other substrate on which the liquid crystal alignment film was formed was turned inside, and after bonding with the previous substrate, the sealant was cured to prepare an empty cell. A negative liquid crystal MLC-3023 (trade name manufactured by Merck Co., Ltd.) containing a polymerizable compound for PSA was injected into this empty cell by a vacuum injection method to prepare a liquid crystal cell.

Next, with a DC voltage of 15 V applied to the liquid crystal cell, UV was irradiated from the outside of the liquid crystal cell through a 325 nm high-pass filter at 10 J / cm ² (also referred to as primary PSA treatment). The illuminance of UV was measured using UV-MO3A manufactured by ORC. After that, for the purpose of inactivating the unreacted polymerizable compound remaining in the liquid crystal cell, UV (UV lamp: FLR40SUV32 /) was used using a UV-FL irradiation device manufactured by Toshiba Litec Co., Ltd. in a state where no voltage was applied. A liquid crystal display element was obtained by irradiating A-1) for 30 minutes (referred to as secondary PSA treatment).

(1) Evaluation of voltage retention rate Using the liquid crystal display element obtained above, a voltage of 1 V was applied in a hot air circulation oven at 60 ° C. for an application time of 60 microseconds, and then 1667 milliseconds after the application was released. The voltage holding ratio was measured. This value was taken as the voltage holding ratio (VHR _BF ). As the measuring device, VHR-1 manufactured by Toyo Corporation was used. The higher the _{VHR BF, the better.}

(2) Evaluation of high temperature and high humidity resistance After allowing the above liquid crystal display element to stand in a constant temperature and humidity controller (PR-2KP manufactured by ESPEC) with a temperature of 85 ° C. and a humidity of 85% for 8 days, the voltage retention rate Was measured. This value was taken as the voltage holding ratio (VHR _AF ). The amount of decrease in voltage retention rate ΔVHR (%) was calculated from the following formula and evaluated as high temperature and high humidity resistance. The smaller the ΔVHR, the better. The results are shown in Table 1.
ΔVHR = VHR _{BF -VHR AF}

(3) Evaluation of adhesion A sample for evaluation of adhesion was prepared by the procedure shown below. A liquid crystal alignment agent was applied to a 30 mm × 40 mm ITO substrate by spin coating. After drying on a hot plate at 80 ° C. for 90 seconds, it was fired in an infrared heating furnace at 230 ° C. for 20 minutes to form a coating film having a film thickness of 100 nm. The two substrates thus obtained were prepared, a bead spacer having a pore size of 4 μm was applied onto the liquid crystal alignment film surface of one of the substrates, and then a sealant (UV curable type) was dropped. Next, the surface of the other substrate on which the liquid crystal alignment film was formed was turned inside, and after bonding with the previous substrate, the sealant was cured to prepare an empty cell. At that time, the amount of the sealant dropped was adjusted so that the diameter of the sealant after bonding was 3 mm. After fixing the two bonded substrates with clips, they were heat-cured at 120 ° C. for 1 hour to prepare a sample for adhesion evaluation.
After that, the sample substrate was fixed with the tabletop precision universal testing machine AGS-X 500N manufactured by Shimadzu Corporation at the edges of the upper and lower substrates, and then pushed in from the upper part of the center of the substrate to peel off the pressure ( N) was measured. The diameter of the peeling marks remaining on the substrate was measured with a caliper, and the value obtained by dividing the pressure (N) at the time of peeling by the diameter of the peeling marks (peeling strength per unit length) was evaluated as the adhesion. The results obtained are shown in Table 2.

(4) Evaluation of Vertical Orientation Using an LCD analyzer (LCA-LUV42A manufactured by Meiryo Technica Co., Ltd.), the pretilt angle of the liquid crystal display element manufactured above was measured. The difference in pretilt angle between the normal firing condition (20 min) and the harsh condition (60 min) (normal condition-harsh condition = Δ pretilt) was calculated. The smaller the Δpretilt, the better the vertical orientation of the liquid crystal alignment film. The results are shown in Table 2.

[Comparative Example 1]
The obtained polyimide powder (B) was also carried out in the same manner as in Example 1 to obtain a liquid crystal alignment agent (B1).
Further, using the obtained liquid crystal alignment agent (B1), the evaluations (1) to (4) were carried out in the same manner as in Example 1.

[Example 2] to [Comparative example 4]
The liquid crystal alignment agents (C1) to (I1) were obtained by carrying out in the same manner as in Example 1.
Further, the liquid crystal alignment agent (E1) (3.0 g) and the liquid crystal alignment agent (I1) (7.0 g) were mixed and stirred for 3 hours to prepare the liquid crystal alignment agent (E2).

As a result of the above evaluation, it was confirmed that all the samples containing the diamine compound of the present invention had good seal adhesion, high temperature and high humidity resistance, and excellent pretilt angle stability.
On the other hand, it can be seen that the liquid crystal alignment agent to which DA-2 is applied has an excellent resistance to high temperature and high humidity, but has a problem in the stability of the pretilt angle (Comparative Example 1).
In addition, a side chain structure having a larger ring structure is generally introduced for the purpose of improving the stability of the tilt angle, but the highly hydrophobic side chain structure weakens the adhesion to the sealant or the glass substrate. (Comparative example 2).
Furthermore, the seal adhesion is expected to be improved by designing the material of polyamic acid, but it can be seen that conventional polyamic acid is inferior in high temperature and high humidity resistance because it is unstable to stimuli such as humidity and heat. (Comparative Example 4).

The liquid crystal display element using the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention is useful in a wide range such as a liquid crystal display for display, a dimming window for controlling transmission and blocking of light, and an optical shutter. Is.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-08720 filed on March 30, 2018 are cited here as the disclosure of the specification of the present invention. , Incorporate.

Claims (11)

A liquid crystal alignment agent containing a polymer (P) having a partial structure represented by the following formula (I-1) or formula (I-2).

(A is a (n + 1) -valent hydrocarbon group having 1 to 18 carbon atoms, or a group having −O−, −COO−, −CO−, or −NHCO− between carbon-carbon bonds of the hydrocarbon group. S represents a single bond or a hydrocarbon group having 1 to 4 carbon atoms. P ₁ represents a hydroxyl group protected by a thermal desorption group. N is an integer of 1 to 5, and m is 1. It is an integer of ~ 2, and when m is 1, R ₁ represents a hydrocarbon group having 1 to 4 carbon atoms, and when m is 2, R ₁ represents a hydrogen atom. * Is a bond bond to a hydrocarbon group. Shows.) The liquid crystal alignment agent according to claim 1, wherein the polymer (P) further has an amino group protected by a heat-removable group. The liquid crystal alignment agent according to claim 1 or 2, wherein the polymer (P) is at least one polymer selected from the group consisting of a polyimide precursor and a polyimide obtained by imidizing the polyimide precursor. The polyimide precursor is a polymer obtained by using a diamine having a partial structure represented by the formula (I-1) or (I-2) and an amino group protected by a thermal desorption group. The liquid crystal alignment agent according to any one of claims 1 to 3. The liquid crystal alignment agent according to claim 4, wherein the diamine is at least one selected from the group consisting of the following formulas (II-1) to (II-3).

(In the formula, L and M are divalent organic groups, Q is a trivalent organic group, and n represents an integer of 0 to 2. P is the above formula (I-1) or formula (in the formula). represents a structure represented by _I-2), P 2 represents an amino group protected with heat leaving group.) In the formulas (II-1) to (II-3), L and M represent an alkylene group having 1 to 11 carbon atoms, a divalent aliphatic ring structure or a divalent aromatic ring structure. _{Any −CH 2−} of the alkylene group may be substituted with −O−, −COO− or −Si—O—Si− in a non-adjacent combination. It may be replaced with the ring structure shown below. R ₂ represents a hydrocarbon group of carbon sources 1-5.

Any one of claims 4 to 6, wherein the polyimide precursor is a polymer obtained by using a diamine having a side chain structure selected from the group represented by the following formulas [S1] to [S3]. The liquid crystal alignment agent according to.

(X ¹ and X ² are independent, single bond,-(CH ₂ ) _a- (a is an integer of 1 to 15), -CONH-, -NHCO-, -CON (CH ₃ )-, It represents −NH−, −O−, −COO−, −OCO− or − ((CH ₂ ) _a1 −A ₁ ) _m1 −. Of these, a plurality of a1s are independently integers of 1 to 15. , a plurality of _{a 1} represents an oxygen atom or -COO- independently, _{m 1} is .G ¹ and ^{G 2} is a 1-2 are each independently a divalent aromatic having 6 to 12 carbon atoms Represents a divalent cyclic group selected from a group or a divalent alicyclic group having 3 to 8 carbon atoms. Any hydrogen atom on the cyclic group is an alkyl group having 1 to 3 carbon atoms and 1 to 1 carbon atoms. M and n may be substituted with at least one selected from the group consisting of an alkoxyl group of 3, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxyl group having 1 to 3 carbon atoms, or a fluorine atom. They are independently integers of 0 to 3, and the sum of m and n is 1 to 4. R ¹ is an alkyl having 1 to 20 carbon atoms, a lucoxy having 1 to 20 carbon atoms, or a carbon number of 2 to 20 carbon atoms. Any hydrogen representing the alkoxyalkyl of the above ^{and forming R 1} may be substituted with fluorine.)

(X ³ represents a single bond, _{-CONH-, -NHCO-, -CON (CH 3} )-, _{-NH-, -O-, -CH 2} O-, -COO- or -OCO-. R ^{2 represents.} Any hydrogen representing an alkyl having 1 to 20 carbon atoms or an alkoxyalkyl having 2 to 20 carbon atoms ^{and forming R 2} may be substituted with fluorine.)

(X ⁴ represents -CONH-, -NHCO-, -O-, -COO- or -OCO-. R ³ represents a structure having a steroid skeleton. The liquid crystal alignment agent according to any one of claims 1 to 7, wherein the thermally desorbing group is a group that replaces a hydrogen atom at a temperature of 150 to 300 ° C. The liquid crystal alignment agent according to any one of claims 1 to 8, wherein the thermoremovable group is a t-butoxycarbonyl group. A liquid crystal alignment film formed from the liquid crystal alignment agent according to any one of claims 1 to 9. A liquid crystal display element comprising the liquid crystal alignment film according to claim 10.