JP2017156438A - Liquid crystal alignment agent, liquid crystal alignment film and method for manufacturing the same, and liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal alignment agent that can obtain a liquid crystal device excellent in AC afterimage characteristics and reliability.SOLUTION: A polymer (P) containing at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2) is made contained in a liquid crystal alignment agent. In the formula (1) and formula (2), Ais a tetra-valent organic group coupled to four -CO- coupled to Ain an alicyclic structure or a chain structure, where at least one α carbon of the four -CO- is an unsaturated carbon atom; Zis a divalent organic group; Rand Rare each independently a hydrogen atom or a monovalent organic group.SELECTED DRAWING: None

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, a method for producing the same, and a liquid crystal element.

  The liquid crystal element includes a liquid crystal alignment film for controlling the alignment of liquid crystal molecules in the liquid crystal cell. As for the display characteristics of the liquid crystal element, not only the liquid crystal material to be used but also the liquid crystal alignment film for uniformly aligning the liquid crystal plays an important role. In designing the alignment film material, aromatic diamines are used from the viewpoint of ensuring various properties such as orientation and electrical characteristics of the liquid crystal element, from the viewpoint of ensuring the storage stability of the liquid crystal aligning agent, and from the viewpoint of ease of polymerization. The polyamic acid and polyimide used are generally used (see, for example, Patent Document 1).

  When the liquid crystal display element is operated for a long time, the direction of the initial alignment of the liquid crystal is deviated from the initial state, and this may cause an afterimage (particularly, an “AC afterimage” caused by an AC voltage). In order to reduce such an AC afterimage, various alignment film materials have been conventionally proposed (for example, see Patent Document 2).

JP 2011-154100 A Japanese Patent Laying-Open No. 2015-194697

  In recent years, large-screen high-definition liquid crystal televisions are mainly used, and small display terminals such as smartphones and tablet PCs are widely used, and the demand for higher quality for liquid crystal panels is increasing. For this reason, in the liquid crystal element, it is necessary to further improve the AC afterimage characteristics, which is one of the important elements related to display quality. In addition, with the wide use of liquid crystal elements, it is desired to develop a new alignment film material capable of obtaining a highly reliable liquid crystal element that can withstand harsh usage environments.

  The present invention has been made in view of the above problems, and an object thereof is to provide a liquid crystal aligning agent capable of obtaining a liquid crystal element excellent in AC afterimage characteristics and reliability.

  As a result of intensive studies to achieve the above-described problems of the prior art, the present inventors have found that the above-described problems can be solved by using a polymer having a specific partial structure for the alignment film material. The present invention has been completed. Specifically, the following means are provided.

（式（１）及び式（２）中、Ａ^１は、Ａ^１に結合している４個の−ＣＯ−に対して脂環式構造又は鎖状構造で結合し、かつ前記４個の−ＣＯ−のα炭素の少なくとも１個が不飽和炭素原子である４価の有機基であり、Ｚ^１は２価の有機基であり、Ｒ^１及びＲ^２は、それぞれ独立に水素原子又は１価の有機基である。）
＜２＞ 上記＜１＞の液晶配向剤を用いて形成された液晶配向膜。
＜３＞ 上記＜１＞の液晶配向剤を用いて塗膜を形成する工程と、前記塗膜に液晶配向能を付与して液晶配向膜を得る工程と、を含む液晶配向膜の製造方法。
＜４＞ 上記＜２＞に記載の液晶配向膜を備える液晶素子。 <1> A liquid crystal aligning agent comprising a polymer [P] having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In Formula (1) and Formula (2), A ¹ is bonded to four —CO— bonded to A ¹ with an alicyclic structure or a chain structure, and the four — A tetravalent organic group in which at least one α-carbon of CO— is an unsaturated carbon atom; Z ¹ is a divalent organic group; and R ¹ and R ² are each independently a hydrogen atom or a monovalent group. Organic group.)
<2> A liquid crystal alignment film formed using the liquid crystal aligning agent of <1> above.
<3> A method for producing a liquid crystal alignment film, comprising: forming a coating film using the liquid crystal aligning agent of <1>above; and providing a liquid crystal alignment film by imparting a liquid crystal alignment ability to the coating film.
<4> A liquid crystal element comprising the liquid crystal alignment film according to <2>.

  According to the liquid crystal aligning agent of this indication, the liquid crystal element excellent in AC afterimage characteristic and reliability can be obtained.

The schematic block diagram of a FFS type liquid crystal display element. The plane schematic diagram of the top electrode for photo-alignment. (A) is a top view of a top electrode, (b) is the elements on larger scale of a top electrode. The figure which shows the drive electrode of 4 systems. The plane schematic diagram of the top electrode for rubbing processes. (A) is a top view of a top electrode, (b) is the elements on larger scale of a top electrode.

Below, each component contained in the liquid crystal aligning agent of this indication and the other component arbitrarily mix | blended as needed are demonstrated.
Here, in the present specification, the “hydrocarbon group” means a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “chain hydrocarbon group” means a linear or branched hydrocarbon group that does not include a cyclic structure and is composed only of a chain structure, and may be saturated or unsaturated. The “alicyclic hydrocarbon group” means a hydrocarbon group containing only an alicyclic hydrocarbon structure as a ring structure, and may be saturated or unsaturated. However, it is not necessary to be constituted only by the structure of the alicyclic hydrocarbon, and a part thereof may have a chain structure. “Aromatic hydrocarbon group” means a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic hydrocarbon structure. “Organic group” means a group containing a hydrocarbon group, and the structure may contain a hetero atom.

≪Polymer [P] ≫
The liquid crystal aligning agent of this indication contains polymer [P] which has at least 1 type chosen from the group which consists of the partial structure represented by the said Formula (1), and the partial structure represented by the said Formula (2).

A ¹ in the above formulas (1) and (2) is bound to four —CO— in the formula bound to A ¹ in an alicyclic structure or a chain structure, and , A tetravalent organic group in which at least one α carbon of each of the four —CO— is an unsaturated carbon atom. The “four —CO—” means four carbonyl groups derived from the acid moiety (carboxyl group or —COX ² (X ² is a halogen atom)) of the tetracarboxylic acid derivative.

A ¹ may be a group composed only of either an alicyclic structure or a chain structure, or may be a group formed by combining an alicyclic structure and a chain structure. All of the four —CO— bonded to A ¹ may be bonded to the alicyclic structure, or all four may be bonded to the chain structure. Further, when A ¹ is a group formed by combining an alicyclic structure and a chain structure, a part of —CO— is bonded to the alicyclic structure, and the remaining —CO— is bonded to the chain structure. It may be.

The alicyclic structure that A ¹ has is not particularly limited as long as it has one or a plurality of aliphatic rings. When A ¹ is a group consisting only of an alicyclic structure, it is preferably a structure in which four hydrogen atoms are removed from the ring portion of the unsaturated alicyclic hydrocarbon, and the unsaturated fat having 4 to 8 carbon atoms. A structure in which four hydrogen atoms are removed from the ring portion of the cyclic hydrocarbon is more preferable. Specific examples thereof include, for example, cyclobutene ring, cyclopentene ring, cyclohexene ring, 1,3-cyclohexadiene ring, 1,4-cyclohexadiene ring, 1,3-cycloheptadiene, 1,4-cycloheptadiene, 1 , 5-cyclooctadiene and the like, a structure in which four hydrogen atoms are removed from the ring portion of an unsaturated alicyclic hydrocarbon. Among these, a structure in which four hydrogen atoms are removed from an unsaturated alicyclic hydrocarbon having 4 to 6 carbon atoms is particularly preferable.
The chain structure of A ¹ is, for example, a divalent chain hydrocarbon group having 1 to 20 carbon atoms, and at least one methylene group of the chain hydrocarbon group is represented by —O—, —CO—, —COO. —, —NR ⁴ —, —CONR ⁴ — (wherein R ⁴ is a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a protecting group, the same shall apply hereinafter) or a divalent substituted by —S—. Groups and the like. Specific examples of R ⁴ is a protecting group, such as tert- butoxycarbonyl group.

（式（ａｒ−１−１）〜式（ａｒ−１−５）及び式（ａｒ−２−１）〜式（ａｒ−２−４）中、Ｒ^ａは、それぞれ独立にハロゲン原子又は１価の有機基であり、Ｒ^ｂは、それぞれ独立に水素原子、ハロゲン原子又は１価の有機基である。Ｒ^３は、２価の鎖状炭化水素基又は当該鎖状炭化水素基の少なくとも１個のメチレン基を−Ｏ−、−ＣＯ−、−ＣＯＯ−、−ＮＲ^４−、−ＣＯＮＲ^４−又は−Ｓ−で置き換えてなる２価の基である。ｎ２は０〜４の整数であり、ｎ３は０〜６の整数であり、ｎ４は０〜７の整数である。「＊」は−ＣＯ−に結合する結合手であることを示す。） Specific examples of A ¹ are represented by, for example, the following formula (ar-1-1) to formula (ar-1-5) and formula (ar-2-1) to formula (ar-2-4). And the like.

(In formula (ar-1-1) to formula (ar-1-5) and formula (ar-2-1) to formula (ar-2-4), each R ^a is independently a halogen atom or a monovalent group. R ^b is each independently a hydrogen atom, a halogen atom or a monovalent organic group, and R ³ is a divalent chain hydrocarbon group or at least one of the chain hydrocarbon groups A divalent group in which methylene group is replaced by —O—, —CO—, —COO—, —NR ⁴ —, —CONR ⁴ — or —S—, n2 is an integer of 0 to 4, n3 is an integer of 0 to 6, and n4 is an integer of 0 to 7. “*” represents a bond bonded to —CO—.)

The divalent chain hydrocarbon group for R ³ is preferably an alkanediyl group having 1 to 20 carbon atoms, or at least one methylene group of the alkanediyl group is represented by —O—, —CO—, —COO. It is a divalent group substituted by —, —NR ⁴ —, —CONR ⁴ — or —S—. ^Examples of the monovalent organic group for R ^a and R ^b include an alkyl group having 1 to 10 carbon atoms or an alkoxy group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferable. n2-n7 is preferably an integer of 0-2. R ^b is preferably a hydrogen atom. In addition, when it has several R ^<a> , ^Rb in ^a formula, these several R ^<a> , several ^Rb may mutually be same or different.

Among the above, A ¹ is adjacent to at least two α-carbons of the four —CO— in Formulas (1) and (2) bonded to A ^{1 in} that the AC afterimage can be further reduced. In addition, it is preferable that an unsaturated bond is formed by the two adjacent α carbons. Specific examples of such a structure are represented by, for example, the above formula (ar-1-1) to formula (ar-1-4) and formula (ar-2-1) to formula (ar-2-4). And the like. A ¹ is particularly preferably an alicyclic structure containing four —CO— α-carbon atoms in the same ring in view of high AC afterimage reduction effect. Examples include the structures represented by (ar-1-1) to (ar-1-4).

In the above formulas (1) and (2), examples of the monovalent organic group of R ¹ and R ² include a monovalent hydrocarbon group having 1 to 20 carbon atoms and a group having a cinnamic acid structure. . Z ¹ is a residue obtained by removing two primary amino groups of a diamine compound.

（式（５）中、Ａ^１は、上記式（１）及び（２）中のＡ^１と同義である。） The polymer [P] is a polymer having a main skeleton of polyamic acid, polyamic acid ester, or polyimide. Such a polymer [P] is obtained by, for example, reacting a diamine compound with a tetracarboxylic acid derivative that is at least one selected from the group consisting of tetracarboxylic dianhydride, tetracarboxylic acid diester, and tetracarboxylic acid diester dihalide. Can be obtained. Hereinafter, each polymer will be described.
<Polyamic acid>
The polyamic acid (hereinafter referred to as “polyamic acid [P]”) as the polymer [P] is, for example, a tetracarboxylic dianhydride (hereinafter referred to as “specific acid dianhydride”) represented by the following formula (5). .) Can be obtained by reacting a tetracarboxylic dianhydride containing a diamine compound.

(In the formula (5), ^{A 1} has the same meaning as ^{A 1} in the formula (1) and (2).)

The description of (1) and (2) above is applied to specific examples and preferred examples of A ^{1 in} the above formula (5). Specific examples of the specific acid dianhydride include, for example, the following formulas (5-1-1) to (5-1-5) and formulas (5-2-1) to (5-2-3). The compound etc. which are represented by these are mentioned. In addition, specific acid dianhydride may be used individually by 1 type, and may be used in combination of 2 or more type. A ¹ in the above formulas (1) and (2) is a residue obtained by removing two acid anhydride groups from the compound represented by the above formula (5).

  In the synthesis of polyamic acid [P], only the specific acid dianhydride may be used as the tetracarboxylic dianhydride, but other tetracarboxylic dianhydrides other than the specific acid dianhydride may be used in combination. Good. Other tetracarboxylic dianhydrides are not particularly limited, but specific examples include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride, ethylenediaminetetraacetic acid diacetate. Anhydrous, etc .;

Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 5- (2,5-di Oxotetrahydrofuran-3-yl) -3a, 4,5,9b-tetrahydronaphtho [1,2-c] furan-1,3-dione, 5- (2,5-dioxotetrahydrofuran-3-yl) -8 -Methyl-3a, 4,5,9b-tetrahydronaphtho [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro -3 ′-(tetrahydrofuran-2 ′, 5′-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 3 , 5,6-To Carboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone, cyclohexanetetracarboxylic dianhydride, etc .; aromatic tetracarboxylic acid Examples of anhydrides include pyromellitic dianhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, p-phenylenebis (trimellitic acid monoester anhydride), ethylene glycol bis (anhydrotrimelli Tate), 1,3-propylene glycol bis (anhydrotrimellitate), etc .; in addition to those mentioned above, JP 2010-97188 A It can be used tetracarboxylic acid dianhydride described. In addition, in the synthesis | combination of polyamic acid [P], other tetracarboxylic dianhydrides can be used individually by 1 type or in combination of 2 or more types.

  The diamine compound used for the synthesis of the polyamic acid [P] is not particularly limited, and various diamine compounds can be used. Specific examples thereof include aliphatic diamines such as metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, hexamethylenediamine, etc .; alicyclic diamines such as 1,4-diaminocyclohexane, 4, 4'-methylenebis (cyclohexylamine) and the like;

（式（Ｅ−１）中、Ｘ^I及びＸ^IIは、それぞれ独立に、単結合、−Ｏ−、−ＣＯＯ−又は−ＯＣＯ−であり、Ｒ^Ｉは炭素数１〜３のアルカンジイル基であり、Ｒ^ＩＩは単結合又は炭素数１〜３のアルカンジイル基であり、ａは０又は１であり、ｂは０〜２の整数であり、ｃは１〜２０の整数であり、ｄは０又は１である。ただし、ａ及びｂが同時に０になることはない。）
で表される化合物などの側鎖型ジアミン：
ｐ−フェニレンジアミン、４，４’−ジアミノジフェニルメタン、４，４’−ジアミノジフェニルスルフィド、４−アミノフェニル−４’−アミノベンゾエート、４，４’−ジアミノアゾベンゼン、３，５−ジアミノ安息香酸、１，５−ビス（４−アミノフェノキシ）ペンタン、ビス［２−（４−アミノフェニル）エチル］ヘキサン二酸、ビス（４−アミノフェニル）アミン、Ｎ，Ｎ−ビス（４−アミノフェニル）メチルアミン、２，６−ジアミノピリジン、１，４−ビス−（４−アミノフェニル）−ピペラジン、Ｎ，Ｎ’−ビス（４−アミノフェニル）−ベンジジン、２，２’−ジメチル−４，４’−ジアミノビフェニル、２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル、４，４’−ジアミノジフェニルエーテル、２，２−ビス［４−（４−アミノフェノキシ）フェニル］プロパン、４，４’−（フェニレンジイソプロピリデン）ビスアニリン、１，４−ビス（４−アミノフェノキシ）ベンゼン、４−（４−アミノフェノキシカルボニル）−１−（４−アミノフェニル）ピペリジン、４，４’−［４，４’−プロパン−１，３−ジイルビス（ピペリジン−１，４−ジイル）］ジアニリンなどの非側鎖型ジアミンを；
ジアミノオルガノシロキサンとして、例えば、１，３−ビス（３−アミノプロピル）−テトラメチルジシロキサンなどを；それぞれ挙げることができるほか、特開２０１０−９７１８８号公報に記載のジアミンを用いることができる。なお、ポリアミック酸［Ｐ］の合成に際し、その他のジアミンは１種を単独で又は２種以上を組み合わせて使用できる。 Examples of aromatic diamines include dodecanoxydiaminobenzene, hexadecanoxydiaminobenzene, octadecanoxydiaminobenzene, cholestanyloxydiaminobenzene, cholesteryloxydiaminobenzene, cholesteryl diaminobenzoate, cholesteryl diaminobenzoate, and diaminobenzoic acid. Lanostanyl, 3,6-bis (4-aminobenzoyloxy) cholestane, 3,6-bis (4-aminophenoxy) cholestane, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butyl Cyclohexane, 2,5-diamino-N, N-diallylaniline, the following formula (E-1)

(In formula (E-1), X ^I and X ^II are each independently a single bond, —O—, —COO— or —OCO—, and R ^I is an alkanediyl group having 1 to 3 carbon atoms. R ^II is a single bond or an alkanediyl group having 1 to 3 carbon atoms, a is 0 or 1, b is an integer of 0 to 2, c is an integer of 1 to 20, and d is 0 or 1. However, a and b are not 0 at the same time.)
Side-chain diamines such as compounds represented by:
p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 4-aminophenyl-4′-aminobenzoate, 4,4′-diaminoazobenzene, 3,5-diaminobenzoic acid, 1 , 5-bis (4-aminophenoxy) pentane, bis [2- (4-aminophenyl) ethyl] hexanedioic acid, bis (4-aminophenyl) amine, N, N-bis (4-aminophenyl) methylamine 2,6-diaminopyridine, 1,4-bis- (4-aminophenyl) -piperazine, N, N′-bis (4-aminophenyl) -benzidine, 2,2′-dimethyl-4,4′- Diaminobiphenyl, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 4,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4 '-(phenylenediisopropylidene) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4- (4-aminophenoxycarbonyl) -1 Non-side chain diamines such as-(4-aminophenyl) piperidine, 4,4 '-[4,4'-propane-1,3-diylbis (piperidine-1,4-diyl)] dianiline;
Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane; and the diamines described in JP-A 2010-97188 can be used. In the synthesis of polyamic acid [P], other diamines can be used singly or in combination of two or more.

Specific examples of the compound represented by the formula (E-1) include compounds represented by the following formula (E-1-1) and formula (E-1-2), for example.

  In the synthesis of the polyamic acid [P], the use ratio of the specific acid dianhydride is preferably 10 mol% or more, more preferably 30 mol% or more with respect to the total amount of the tetracarboxylic dianhydride used for the synthesis. More preferably, it is more preferably 50 mol% or more. Further, from the viewpoint of obtaining a liquid crystal element with less AC afterimage, the diamine compound used for the synthesis preferably contains an aromatic diamine. The use ratio of the aromatic diamine is preferably 30 mol% or more, more preferably 50 mol% or more, based on the total of the diamine compounds used for the synthesis of the polyamic acid [P].

  The polyamic acid [P] can be obtained by reacting the tetracarboxylic dianhydride and the diamine compound as described above with a molecular weight modifier as necessary. The ratio of the tetracarboxylic dianhydride and the diamine compound used for the polyamic acid synthesis reaction is such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 with respect to 1 equivalent of the amino group of the diamine compound. A ratio of ˜2 equivalents is preferred. Examples of the molecular weight modifier include acid monoanhydrides such as maleic anhydride, phthalic anhydride and itaconic anhydride, monoamine compounds such as aniline, cyclohexylamine and n-butylamine, and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. Can be mentioned. It is preferable that the usage-amount of a molecular weight modifier shall be 20 mass parts or less with respect to 100 mass parts of total of the tetracarboxylic dianhydride and diamine compound to be used.

The synthesis reaction of polyamic acid [P] is preferably performed in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., and the reaction time is preferably 0.1 to 24 hours. Examples of the organic solvent used in the reaction include aprotic polar solvents, phenol solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, and the like. Particularly preferred organic solvents are N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol. And at least one selected from the group consisting of halogenated phenols, or a mixture of one or more of these with another organic solvent (for example, butyl cellosolve, diethylene glycol diethyl ether, etc.) preferable. The amount (a) of the organic solvent used is such that the total amount (b) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 50% by mass with respect to the total amount (a + b) of the reaction solution. It is preferable.
As described above, a reaction solution obtained by dissolving polyamic acid [P] is obtained. This reaction solution may be used for the preparation of the liquid crystal aligning agent as it is, or may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid [P] contained in the reaction solution.

<Polyamic acid ester>
The polyamic acid ester as the polymer [P] includes, for example, (I) a polyamic acid [P] obtained by the above synthesis reaction and an esterifying agent (for example, methanol, ethanol, N, N-dimethylformamide diethyl acetal, etc.) (II) A tetracarboxylic acid diester and a diamine are reacted with an appropriate dehydration catalyst (for example, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl)-in an organic solvent. A method of reacting in the presence of 4-methylmorpholinium halide, phosphorus condensing agent, etc., [III] tetracarboxylic acid diester dihalide and diamine in an organic solvent in a suitable base (for example, pyridine, triethylamine, For example, by a reaction in the presence of sodium hydroxide).
The resulting polyamic acid ester may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist. The reaction solution obtained by dissolving the polyamic acid ester may be used for the preparation of the liquid crystal aligning agent as it is, or may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid ester contained in the reaction solution.

<Polyimide>
The polyimide as the polymer [P] can be obtained, for example, by dehydrating and ring-closing and imidizing the polyamic acid [P] synthesized as described above. The polyimide may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure possessed by the polyamic acid that is the precursor, and only a part of the amic acid structure may be dehydrated and cyclized. It may be a partially imidized product in which a ring structure coexists. The polyimide used for the reaction preferably has an imidation ratio of 20 to 99%, more preferably 30 to 90%. This imidation ratio represents the ratio of the number of imide ring structures to the total of the number of polyimide amic acid structures and the number of imide ring structures in percentage. Here, a part of the imide ring may be an isoimide ring.

The polyamic acid is preferably dehydrated and closed by heating the polyamic acid, or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring-closing catalyst to the solution, and heating the solution as necessary. . Of these, the latter method is preferred.
In the method of adding a dehydrating agent and a dehydrating ring-closing catalyst to a polyamic acid solution, as the dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. It is preferable that the usage-amount of a dehydrating agent shall be 0.01-20 mol with respect to 1 mol of the amic acid structure of a polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, triethylamine and the like can be used. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. As an organic solvent to be used, the organic solvent illustrated as what is used for the synthesis | combination of a polyamic acid can be mentioned. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C., and the reaction time is preferably 1.0 to 120 hours. In this way, a reaction solution containing polyimide is obtained. This reaction solution may be used for the preparation of the liquid crystal aligning agent as it is, or may be used for the preparation of the liquid crystal aligning agent after isolating the polyimide.

  The solution viscosity of the polymer [P] is preferably that having a solution viscosity of 10 to 800 mPa · s when the solution is a 10% by mass solution, and having a solution viscosity of 15 to 500 mPa · s. It is more preferable that In addition, the said solution viscosity (mPa * s) is E type | mold about the polymer solution with a density | concentration of 10 mass% prepared using the good solvent (For example, (gamma) -butyrolactone, N-methyl-2-pyrrolidone, etc.) of these polymers. It is a value measured at 25 ° C. using a rotational viscometer.

  The weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of the polymer [P] is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. It is. Moreover, the molecular weight distribution (Mw / Mn) represented by the ratio between Mw and the polystyrene-equivalent number average molecular weight (Mn) measured by GPC is preferably 15 or less, more preferably 10 or less. In addition, the liquid crystal aligning agent of this indication may contain only 1 type of polymers [P], and may contain 2 or more types.

≪Other ingredients≫
The liquid crystal aligning agent of this indication may contain other components other than polymer [P] with polymer [P]. As other components, a polymer having neither the partial structure represented by the above formula (1) nor the partial structure represented by the above formula (2) (hereinafter referred to as “other polymer”), molecule. Examples include compounds having at least one epoxy group, functional silane compounds, photopolymerizable compounds, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, and photosensitizers. It is done. The main skeleton of the other polymer is not particularly limited, and examples thereof include polyamic acid, polyamic acid ester, polyimide, polyester, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene-phenylmaleimide) derivative, and poly (meth) acrylate. Can be mentioned. The blending ratio of these other components can be appropriately selected according to each compound as long as the effects of the present disclosure are not impaired.

<Solvent>
The liquid crystal aligning agent of the present disclosure is prepared as a liquid composition in which the polymer [P] and other components used as necessary are preferably dispersed or dissolved in an appropriate solvent.
Examples of the organic solvent used include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactam, and N, N-dimethylformamide. N, N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, Ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether Ether acetate, 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, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, A propylene carbonate etc. can be mentioned. These can be used alone or in admixture of two or more.

The solid content concentration in the liquid crystal aligning agent (the ratio of the total mass of components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc. It is the range of 1-10 mass%. That is, the liquid crystal aligning agent is applied to the substrate surface as will be described later, and preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that becomes a liquid crystal alignment film. At this time, when the solid content concentration is less than 1% by mass, the film thickness of the coating film is too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by mass, it is difficult to obtain a good liquid crystal alignment film because the film thickness is excessive, and the viscosity of the liquid crystal aligning agent increases and the applicability decreases. There is a tendency.
The content ratio of the polymer [P] in the liquid crystal aligning agent of the present disclosure is preferably 5 parts by mass or more, more preferably 10 parts per 100 parts by mass in total of the solid components (components other than the solvent) in the liquid crystal aligning agent. It is at least 30 parts by mass, more preferably at least 30 parts by mass.

  The reason why a liquid crystal element having good AC afterimage characteristics and reliability is obtained when a liquid crystal aligning agent containing the polymer [P] is used is not clear, but one hypothesis is that the tetracarboxylic acid derivative When at least one α carbon of —CO— derived from the acid portion is an unsaturated carbon atom, the imidation ratio of the polymer [P] in the alignment film can be increased by heating during post-baking, and thereby It is presumed that the interaction between the liquid crystal alignment film and the liquid crystal molecules was improved and the AC afterimage could be reduced. In addition, aromatic diamines are used from the viewpoint of ensuring liquid crystal orientation and electrical properties by -CO- derived from the acid moiety of the tetracarboxylic acid derivative being bonded to an alicyclic structure or a chain structure. In this case, it is presumed that a highly reliable liquid crystal element was obtained as a result of shortening the conjugate length and reducing light absorption of the alignment film resin. Note that the above hypothesis is just a guess and does not limit the present disclosure.

≪Liquid crystal alignment film and liquid crystal element≫
The liquid crystal alignment film of the present disclosure is formed by the liquid crystal aligning agent prepared as described above. Moreover, the liquid crystal element of this indication comprises the liquid crystal aligning film formed using the liquid crystal aligning agent demonstrated above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and includes, for example, a TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, VA (Vertical Alignment) type (including VA-MVA type, VA-PVA type, etc.). It can be applied to various modes such as IPS (In-Plane Switching) type, FFS (fringe field switching) type, OCB (Optically Compensated Bend) type. A liquid crystal element can be manufactured by the method including the following processes 1 to 3, for example. In step 1, the substrate to be used varies depending on the desired operation mode. Step 2 and step 3 are common to each operation mode.

(Step 1: Formation of coating film)
First, a liquid crystal aligning agent is applied on a substrate, and a coating film is preferably formed on the substrate by heating the coated surface. As the substrate, for example, glass such as float glass or soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, poly (cycloaliphatic olefin) can be used. As a transparent conductive film provided on one surface of the substrate, an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), etc. Can be used. In the case of manufacturing a TN type, STN type, or VA type liquid crystal element, two substrates provided with a patterned transparent conductive film are used. On the other hand, when manufacturing an IPS type or FFS type liquid crystal element, a substrate provided with an electrode made of a transparent conductive film or a metal film patterned in a comb shape, and a counter substrate provided with no electrode Is used. As the metal film, for example, a film made of a metal such as chromium can be used. Application of the liquid crystal aligning agent to the substrate is preferably performed on the electrode forming surface by an offset printing method, a spin coating method, a roll coater method or an ink jet printing method.

  After applying the liquid crystal aligning agent, preheating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied liquid crystal aligning agent. The prebake temperature is preferably 30 to 200 ° C., and the prebake time is preferably 0.25 to 10 minutes. Thereafter, the solvent is completely removed, and if necessary, a baking (post-baking) step is performed for the purpose of thermally imidizing the amic acid structure present in the polymer. The firing temperature (post-bake temperature) at this time is preferably 80 to 300 ° C., and the post-bake time is preferably 5 to 200 minutes. The thickness of the film thus formed is preferably 0.001 to 1 μm. After applying the liquid crystal aligning agent on the substrate, the organic solvent is removed to form a liquid crystal aligning film or a coating film that becomes the liquid crystal aligning film.

(Step 2: Orientation treatment)
When manufacturing a TN-type, STN-type, IPS-type, or FFS-type liquid crystal element, a treatment (orientation treatment) for imparting liquid crystal alignment ability to the coating film formed in Step 1 is performed. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film. As the alignment treatment, for example, a rubbing treatment that imparts liquid crystal alignment ability to the coating film by rubbing the coating film in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, cotton, etc., a coating film formed on the substrate And a photo-alignment treatment for imparting liquid crystal alignment ability to the coating film. On the other hand, when manufacturing a vertical alignment type liquid crystal element, the coating film formed in the above step 1 can be used as it is as a liquid crystal alignment film, but the coating film may be subjected to an alignment treatment.

(Process 3: Construction of liquid crystal cell)
Two substrates on which the liquid crystal alignment film is formed as described above are prepared, and a liquid crystal cell is manufactured by disposing a liquid crystal between the two substrates disposed to face each other. To manufacture a liquid crystal cell, for example, (1) two substrates are arranged opposite to each other with a gap so that the liquid crystal alignment films face each other, and the peripheral portions of the two substrates are bonded together using a sealant. , A method of injecting and filling liquid crystal into the cell gap defined by the substrate surface and the sealing agent, and then sealing the injection hole; (2) sealing agent at a predetermined place on one substrate on which the liquid crystal alignment film is formed; After applying the liquid crystal and dropping the liquid crystal to several places on the liquid crystal alignment film surface, the other substrate is bonded so that the liquid crystal alignment film faces and the liquid crystal is spread over the entire surface of the substrate (ODF method), etc. Is mentioned. The manufactured liquid crystal cell is preferably heated to a temperature at which the used liquid crystal takes an isotropic phase, and then slowly cooled to room temperature to remove the flow alignment at the time of filling the liquid crystal.

  As the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used. Examples of the liquid crystal include nematic liquid crystals and smectic liquid crystals. Among them, nematic liquid crystals are preferable. For example, Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, biphenyls. Cyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, and the like can be used. Further, for example, a cholesteric liquid crystal, a chiral agent, or a ferroelectric liquid crystal may be added to these liquid crystals.

  Subsequently, a polarizing plate is bonded to the outer surface of the liquid crystal cell as necessary. Thereby, a liquid crystal element is obtained. Examples of the polarizing plate include a polarizing plate comprising a polarizing film called an “H film” in which iodine is absorbed while stretching and orientation of polyvinyl alcohol is sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself. When the rubbing treatment is performed on the coating film, the two substrates are arranged to face each other so that the rubbing directions in each coating film are at a predetermined angle, for example, orthogonal or antiparallel.

  The liquid crystal element of the present disclosure can be effectively applied to various applications, for example, watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors. It can be used for various display devices such as liquid crystal televisions and information displays, and light control films. Moreover, the liquid crystal element formed using the liquid crystal aligning agent of this indication can also be applied to retardation film.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

In the following examples, the solution viscosity of the polymer solution and the imidization rate of the polymer were measured by the following methods.
[Solution Viscosity (mPa · s) of Polymer Solution]: A solution prepared to a polymer concentration of 10% by mass using a predetermined solvent was measured at 25 ° C. using an E-type rotational viscometer.
[Polymer imidation ratio (%)]: A solution containing polyimide was poured into pure water, and the resulting precipitate was sufficiently dried at room temperature under reduced pressure, and then dissolved in deuterated dimethyl sulfoxide to obtain tetramethylsilane. Was used as a reference substance, and ¹ H-NMR was measured at room temperature. From the obtained ¹ H-NMR spectrum, the imidation ratio was determined using the following mathematical formula (1).
Imidation ratio (%) = (1-B ¹ / B ² × α) × 100 (1)
(In Formula (1), B ¹ is a peak area derived from protons of NH groups appearing near a chemical shift of 10 ppm, B ² is a peak area derived from other protons, and α is a precursor of a polymer (polyamic acid) The number ratio of other protons to one proton of NH group in)
Abbreviations and structures of monomers used in the following polymerization are shown below. Hereinafter, the “compound represented by the formula (X)” may be simply abbreviated as “compound (X)”.

<Synthesis of polymer>
[Synthesis Example 1-1]
15.24 g of compound (AN-1) as tetracarboxylic dianhydride (93 mol parts with respect to 100 mol parts of the total amount of diamine compounds used in the synthesis), and 4,4′-diaminodiphenylmethane as the diamine compound 14.76 g (100 mol parts) was dissolved in a mixed solvent of 85 g of N-methyl-2-pyrrolidone (NMP) and 85 g of γ-butyrolactone (GBL), and reacted at 30 ° C. for 12 hours. The reaction mixture was then poured into a large excess of methanol to precipitate the reaction product. The recovered precipitate was washed with methanol, and then dried at 40 ° C. under reduced pressure for 15 hours to obtain 28.4 g of polyamic acid (hereinafter referred to as polymer (PA-1)). The obtained polymer (PA-1) was prepared to be 15% by mass with a solvent composition of NMP: GBL = 50: 50 (mass ratio), and the viscosity of this solution was measured to find 364 mPa · s. It was. Further, when this polymer solution was allowed to stand at 20 ° C. for 3 days, it did not gel and the storage stability was good.

[Synthesis Example 1-2 to Synthesis Example 1-10]
A polyamic acid was obtained in the same manner as in Synthesis Example 1-1 except that the types and amounts of tetracarboxylic dianhydride and amine compound used in the reaction were changed as shown in Table 1 below. When each of the polymer solutions obtained in Synthesis Example 1-2 to Synthesis Example 1-10 was allowed to stand at 20 ° C. for 3 days, none of them was gelled, and the storage stability was good.

The numerical values in Table 1 indicate, for tetracarboxylic dianhydrides, the usage ratio (mol%) relative to the total amount of tetracarboxylic dianhydrides used in the reaction, and for diamine compounds, the diamine compounds used in the reaction. The use ratio (mol%) with respect to the total amount of is shown. Abbreviations of tetracarboxylic dianhydride and diamine compound in Table 1 are as follows.
(Tetracarboxylic dianhydride)
AN-5; 1,2,3,4-cyclobutanetetracarboxylic dianhydride AN-6; pyromellitic dianhydride AN-7; compound AN-8 represented by the above formula (AN-7); , 2,3,4-Butanetetracarboxylic dianhydride (diamine compound)
DA-1; paraphenylenediamine DA-2; 4,4′-diaminodiphenylmethane DA-3; bis [2- (4-aminophenyl) ethyl] hexanedioic acid DA-4; 1,2-bis (4-amino) Phenoxy) ethane DA-5; 4,4′-diaminodiphenylamine DA-6; 3,5-diaminobenzoic acid DA-7; N- (2,4-diaminophenyl) -4- (4-heptylcyclohexyl) benzamide DA -8; 4- (tetradecaoxy) benzene-1,3-diamine DA-9; cholestanyl 3,5-diaminobenzoate The polymer (PA-5) is particularly suitable for a TN type liquid crystal display element, The polymer (PA-6) is particularly suitable for a VA liquid crystal display element (including a PSA display system).

[Synthesis Example 2-1]
26.06 g of compound (AN-1) as tetracarboxylic dianhydride (98 mol parts relative to 100 mol parts of the total amount of diamine compounds used in the synthesis), and 4,4′-diaminodiphenylmethane as the diamine compound 23.94 g (100 mol parts) was dissolved in 200 g of NMP and reacted at 60 ° C. for 6 hours. Next, 250 g of NMP was added, 9.36 g of pyridine and 12.08 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 6 hours. The reaction mixture was then poured into a large excess of methanol to precipitate the reaction product. The recovered precipitate was washed with methanol and then dried under reduced pressure at 40 ° C. for 15 hours to obtain a polyimide having an imidation ratio of about 50% (hereinafter referred to as polymer (PI-1)). The obtained polymer (PI-1) was prepared so that it might become 15 mass% with NMP. It was 620 mPa * s when the viscosity of this solution was measured. Moreover, when the obtained polymer solution was allowed to stand at 20 ° C. for 3 days, it did not gel and the storage stability was good.

<Preparation and evaluation of liquid crystal aligning agent>
[Example 1: Photo-alignment FFS type liquid crystal display element]
(1) Preparation of liquid crystal aligning agent The polymer (PA-3) obtained in Synthesis Example 1-3 as a polymer was obtained from γ-butyrolactone (GBL), N-methyl-2-pyrrolidone (NMP), and butyl cellosolve (BC). The resulting solution was dissolved in a mixed solvent (GBL: NMP: BC = 40: 40: 20 (mass ratio)) to obtain a solution having a solid content concentration of 4.0% by mass. The liquid crystal aligning agent (R-1) was prepared by filtering this solution through a filter having a pore diameter of 0.2 μm.

(2) Evaluation of applicability The liquid crystal aligning agent (R-1) prepared above was applied on a glass substrate using a spinner, prebaked on a hot plate at 80 ° C. for 1 minute, and then the interior was filled with nitrogen. A coating film having an average film thickness of 0.1 μm was formed by heating (post-baking) in a substituted 200 ° C. oven for 1 hour. This coating film was observed with a microscope having a magnification of 100 times and 10 times to examine the presence or absence of film thickness unevenness and pinholes. In the evaluation, when neither film thickness unevenness nor pinhole was observed even when observed with a 100 × microscope, the coating property was “good”, and with a 100 × microscope, at least one of film thickness unevenness and pinhole was observed. However, when both the film thickness unevenness and the pinhole were not observed with a 10 × microscope, the coating property was “Yes”. When the film thickness unevenness and / or pinhole was clearly observed with a 10 × microscope Was defined as “poor”. In this example, neither film thickness unevenness nor pinhole was observed even with a 100 × microscope, and the coating property was “good”.

(3) Production of FFS type liquid crystal display element by photo-alignment method FFS type liquid crystal display element 10 shown in FIG. 1 was produced. First, a glass substrate 11a having an electrode pair on one side of which a bottom electrode 15 having no pattern, a silicon nitride film as an insulating layer 14, and a top electrode 13 patterned in a comb shape are formed in this order, and an electrode The liquid crystal aligning agent (R-1) prepared in the above (1) is paired with the opposite glass substrate 11b not provided with the glass substrate 11a, and the surface of the glass substrate 11a having the transparent electrode and one surface of the opposite glass substrate 11b. And using a spinner. Next, this was pre-baked for 1 minute on an 80 ° C. hot plate to form a coating film. Next, each surface of these coating films is irradiated with polarized ultraviolet rays 300 mJ / cm ² containing a 254 nm emission line from the normal direction of the substrate using a Hg-Xe lamp and a Grand Taylor prism, and a pair of liquid crystal alignment films are provided. A substrate was obtained. Then, it heated for 15 minutes at 230 degreeC in the oven which substituted the inside with nitrogen (post-baking), and formed the coating film with an average film thickness of 0.1 micrometer.
A schematic plan view of the top electrode 13 used here is shown in FIG. 2A is a top view of the top electrode 13, and FIG. 2B is an enlarged view of a portion C1 surrounded by a broken line in FIG. 2A. In this example, a substrate having a top electrode having a line width d1 of electrodes of 4 μm and a distance d2 between the electrodes of 6 μm was used. In addition, as the top electrode 13, four systems of drive electrodes of electrode A, electrode B, electrode C, and electrode D were used. FIG. 3 shows the configuration of the drive electrode used. In this case, the bottom electrode 15 functions as a common electrode that acts on all of the four drive electrodes, and each of the four drive electrode regions serves as a pixel region. In addition, the light irradiation treatment for the coating film is performed by setting the polarization plane direction so that the direction of the line segment projected onto the substrate with the polarization plane of polarized ultraviolet light is the direction of the double-headed arrow in FIG. Was performed by irradiating polarized ultraviolet rays.

Next, an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm is applied to the outer periphery of the surface of the substrate having the liquid crystal alignment film by screen printing. It was made to oppose and it piled up and crimped | bonded so that the direction which the polarization plane of polarized ultraviolet rays projected on the board | substrate might become parallel, and the adhesive was thermoset at 150 degreeC over 1 hour. Next, a liquid crystal “MLC-6221” manufactured by Merck & Co. was filled into the gap between the liquid crystal injection port and the liquid crystal injection port was sealed with an epoxy resin adhesive. Then, in order to remove the flow alignment at the time of liquid crystal injection, this was heated to 150 ° C. and then gradually cooled to room temperature.
Next, an FFS type liquid crystal display element was manufactured by laminating polarizing plates on both outer surfaces of the substrate. At this time, one of the polarizing plates is stuck so that the polarization direction thereof is parallel to the direction of projection of the polarization plane of the polarized ultraviolet light of the liquid crystal alignment film onto the substrate surface, and the other one has the polarization direction first. The polarizing plate was stuck so as to be orthogonal to the polarization direction of the polarizing plate.

(4) Evaluation of liquid crystal alignment The presence / absence of an abnormal domain in the change in brightness when a voltage of 5 V is turned ON / OFF (applied / released) is measured with a microscope at a magnification of 50 for the FFS type liquid crystal display device manufactured in (3) above. Observed at double. In the evaluation, when the abnormal domain was not observed, the liquid crystal alignment was “good”, and when the abnormal domain was observed, the liquid crystal alignment was “bad”. In this liquid crystal display element, the liquid crystal orientation was “good”.
(5) Evaluation of voltage holding ratio For the FFS type liquid crystal display device manufactured in the above (3), a voltage of 5 V was applied at 23 ° C. with an application time of 60 microseconds and a span of 167 milliseconds, and 1 When the voltage holding ratio (VHR) after 1,000 milliseconds was measured, it was 98.5%. In addition, as a measuring apparatus, Toyo Technica Co., Ltd. make and VHR-1 were used.

(6) Evaluation of reliability With respect to the FFS type liquid crystal display device manufactured in the above (3), the voltage holding ratio was measured in the same manner as in the above (5), and the value was defined as the initial VHR (VHR _BF ). Next, the liquid crystal display element after the initial VHR measurement was allowed to stand in an 80 ° C. oven under LED lamp irradiation for 500 hours, and then allowed to stand at room temperature and naturally cooled to room temperature. With respect to the liquid crystal cell after light irradiation, the voltage holding ratio was measured by the same method as in the above (5), and this value was defined as VHR (VHR _AFB ) after light stress. The decrease amount ΔVHR _BL (%) of the voltage holding ratio was obtained from the following formula (2), and the reliability of the liquid crystal display element was evaluated.
ΔVHR _BL = ((VHR _BF −VHR _AFB ) ÷ VHR _BF ) × 100 (2)
When ΔVHR _BL was less than 3%, the reliability was judged as “good”, when it was 3% or more and less than 5%, “good”, and when it was 5% or more, it was judged as “bad”. As a result, ΔVHR _BL of the liquid crystal display element of this example was 1.2%, and the reliability was “good”.

(7) Contrast evaluation after driving stress (AC afterimage characteristics evaluation)
An FFS type liquid crystal cell was produced by performing the same operation as in the above (3) except that the polarizing plate was not bonded to both outer surfaces of the substrate. About this FFS type liquid crystal cell, after driving for 30 hours at an AC voltage of 10 V, using a device in which a polarizer and an analyzer are arranged between a light source and a light quantity detector, the minimum relative value expressed by the following formula (3) is used. The transmittance (%) was measured.
Minimum relative transmittance (%) = (β−B ⁰ ) / (B ¹⁰⁰ −B ⁰ ) × 100 (3)
(In Formula (3), B ⁰ is the transmission amount of light under a crossed Nicol in a blank. B ¹⁰⁰ is the transmission amount of light under a Paranicol in a blank. Β is a polarizer under a crossed Nicol. (This is the minimum light transmission amount with the liquid crystal cell sandwiched between the analyzers.)
The black level in the dark state is represented by the minimum relative transmittance of the liquid crystal cell. In the FFS type liquid crystal cell, the smaller the black level in the dark state, the better the contrast. AC residual image characteristics with a minimum relative transmittance of less than 1.0% are considered “good”, those with 1.0% or more and less than 1.5% are “good”, and those with 1.5% or more are “bad”. It was. As a result, the minimum relative transmittance of this liquid crystal cell was 0.1%, and the AC afterimage characteristics were determined to be “good”.

[Example 2: rubbing alignment FFS type liquid crystal display element]
(1) Preparation of liquid crystal aligning agent The polymer (PA-1) obtained in Synthesis Example 1-1 as a polymer was obtained from γ-butyrolactone (GBL), N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC). The resulting solution was dissolved in a mixed solvent (GBL: NMP: BC = 40: 40: 20 (mass ratio)) to obtain a solution having a solid content concentration of 4.5 mass%. A liquid crystal aligning agent (R-2) was prepared by filtering this solution through a filter having a pore diameter of 0.2 μm.

(2) Evaluation of applicability The liquid crystal aligning agent (R-2) prepared above was applied on a glass substrate using a spinner, prebaked on a hot plate at 80 ° C. for 1 minute, and then the interior was filled with nitrogen. A coating film having an average film thickness of 0.1 μm was formed by heating (post-baking) in a substituted 200 ° C. oven for 1 hour. Using the obtained coating film, coatability was evaluated in the same manner as in (2) of Example 1 above. As a result, the coating property of this coating film was “good”.
(3) Measurement of imidation ratio of polymer component in coating film Absorption in the vicinity of 1381 cm ⁻¹ in the FT-IR measurement (C—N—C bending vibration = imide bond) for the coating film obtained in (2) above. ) And the peak area ratio between absorption near 1503 cm ⁻¹ (absorption of amic acid bond), and the imidation ratio (%) was calculated by the following formula (4).
Imidation rate (%) = {α1 / (α1 + α2)} × 100 (4)
(In Equation (4), [alpha] 1 is the peak area of absorption around 1381cm ^-1, α2 is the peak area of absorption around 1503cm ^-1.)
Note that α2 is a value obtained by calculating the peak area with the absorption in the vicinity of 1503 cm ⁻¹ being 0, although the coating film was heated on a hot plate at 300 ° C. for 10 minutes. As a result, the imidation ratio of this coating film was 98%.

(4) Manufacture of FFS type liquid crystal display element by rubbing treatment First, each surface of a pair of glass substrates 11a, 11b similar to that used in (3) of Example 1 was prepared in (1) above. The liquid crystal aligning agent (R-2) was applied using a spinner to form a coating film. Next, this coating film was pre-baked for 1 minute on an 80 ° C. hot plate, and then heated (post-baked) for 15 minutes at 230 ° C. in an oven in which the inside of the chamber was purged with nitrogen, so that the average film thickness was 0.1 μm. A coating film was formed. A schematic plan view of the top electrode 13 used here is shown in FIG. 4A is a top view of the top electrode 13, and FIG. 4B is an enlarged view of a portion C1 surrounded by a broken line in FIG. 4A. In this example, the line width d1 of the electrodes was 4 μm, and the distance d2 between the electrodes was 6 μm. As the top electrode 13, four drive electrodes were used as in the first embodiment (see FIG. 3).
Subsequently, the surface of the coating film formed on the glass substrates 11 a and 11 b was rubbed with cotton to form the liquid crystal alignment film 12. In FIG.4 (b), the rubbing direction with respect to the coating film formed on the glass substrate 11a is shown by the arrow. Next, after applying a sealant to the outer edge of the surface having the liquid crystal alignment film in one of the pair of substrates, the rubbing directions of the substrates 11a and 11b are antiparallel to each other. The sealing agent was cured by bonding through a spacer having a diameter of 3.5 μm. Next, liquid crystal “MLC-6221” (manufactured by Merck & Co., Inc.) was injected between the pair of substrates through the liquid crystal injection port to form the liquid crystal layer 16. Furthermore, the liquid crystal display element 10 was produced by bonding a polarizing plate (not shown) on both outer surfaces of the substrates 11a and 11b so that the polarization directions of the two polarizing plates were orthogonal to each other.

(5) Evaluation of liquid crystal alignment The rubbing type FFS liquid crystal display device manufactured in the above (4) was evaluated for liquid crystal alignment in the same manner as in (4) of Example 1 above. As a result, this liquid crystal display element had “good” liquid crystal alignment.
(6) Evaluation of voltage holding ratio The voltage holding ratio of the rubbing type FFS liquid crystal display element manufactured in the above (4) was measured in the same manner as in (5) of Example 1 above. As a result, it was 99.1%.
(7) Evaluation of reliability The rubbing type FFS liquid crystal display device manufactured in (4) above was measured for reliability in the same manner as in (6) of Example 1 above. As a result, ΔVHR _BL was 1.1%, and the reliability of the liquid crystal display element of this example was “good”.
(8) Contrast evaluation after driving stress (AC afterimage characteristics evaluation)
The same operation as in the above (4) was performed except that the polarizing plate was not bonded to both outer surfaces of the substrate, and an FFS type liquid crystal cell was produced by a rubbing method. With respect to this FFS type liquid crystal cell, the AC afterimage characteristics were measured in the same manner as in (7) of Example 1 above. As a result, the minimum relative transmittance of this liquid crystal cell was 0.2%, and the AC afterimage characteristics were determined to be “good”.

[Examples 3-6, Comparative Examples 1-4]
In Example 2 above, a liquid crystal aligning agent was prepared in the same manner as in Example 2 except that the type of polymer contained in the liquid crystal aligning agent was changed as shown in Table 2 below, and an FFS type liquid crystal display was prepared by rubbing. The device or the liquid crystal cell was manufactured and various evaluations were performed. The evaluation results are shown in Table 2 below.

  In Examples 1 to 4 and 6, the coating property of the liquid crystal aligning agent and the liquid crystal alignment property, voltage holding ratio, reliability, and AC afterimage characteristics in the liquid crystal display element are all “good” results. It was balanced. In Example 5, the AC afterimage characteristics were evaluated as “good” and the voltage holding ratio was slightly low at 98.2%, but the coating property, liquid crystal alignment property, and reliability were different from those in other examples. Similarly good results. On the other hand, Comparative Examples 1-4 was a result inferior to an Example in several evaluation items.

  DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display element, 11a, 11b ... Glass substrate, 12 ... Liquid crystal aligning film, 13 ... Top electrode, 14 ... Insulating layer, 15 ... Bottom electrode, 16 ... Liquid crystal layer

Claims (6)

A liquid crystal aligning agent containing a polymer [P] having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In Formula (1) and Formula (2), A ¹ is bonded to four —CO— bonded to A ¹ with an alicyclic structure or a chain structure, and the four — A tetravalent organic group in which at least one α-carbon of CO— is an unsaturated carbon atom; Z ¹ is a divalent organic group; and R ¹ and R ² are each independently a hydrogen atom or a monovalent group. Organic group.)   The liquid crystal aligning agent according to claim 1, wherein at least two of the four —CO— α carbons are adjacent to each other, and an unsaturated bond is formed by the two adjacent α carbons.   The liquid crystal aligning agent of Claim 1 or 2 in which the ring structure is formed by the alpha carbon of the four -CO-.   The liquid crystal aligning film formed using the liquid crystal aligning agent as described in any one of Claims 1-3.   Liquid crystal alignment including the process of forming a coating film using the liquid crystal aligning agent as described in any one of Claims 1-3, and the process of providing a liquid crystal aligning capability to the said coating film, and obtaining a liquid crystal aligning film. A method for producing a membrane.   A liquid crystal element provided with the liquid crystal aligning film of Claim 4.

Images