JP7107220B2 - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display device using the same.

Liquid crystal display elements are widely used as display units for personal computers, mobile phones, smart phones, televisions, and the like. A liquid crystal display element includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the orientation of liquid crystal molecules in the liquid crystal layer, A thin film transistor (TFT) or the like is provided for switching an electric signal supplied to the pixel electrode. Vertical electric field methods such as TN method and VA method, and horizontal electric field methods such as IPS method and FFS method are known as methods for driving liquid crystal molecules. In the lateral electric field method, in which electrodes are formed only on one side of the substrate and an electric field is applied in a direction parallel to the substrate, a wider field is obtained than in the conventional vertical electric field method, in which a voltage is applied to the electrodes formed on the upper and lower substrates to drive the liquid crystal. It is known as a liquid crystal display element that has viewing angle characteristics and is capable of high-quality display.

Although the lateral electric field type liquid crystal cell has excellent viewing angle characteristics, the electrode portion formed in the substrate is small, so if the voltage holding ratio is low, a sufficient voltage cannot be applied to the liquid crystal, resulting in a decrease in display contrast. In addition, if the stability of the liquid crystal alignment is low, the liquid crystal will not return to its initial state when the liquid crystal is driven for a long period of time, causing a decrease in contrast and an afterimage. Therefore, the stability of the liquid crystal alignment is important. In addition, static electricity tends to accumulate in the liquid crystal cell, and the application of positive and negative asymmetrical voltages generated by driving also causes charge to accumulate in the liquid crystal cell. , the display quality of the liquid crystal element is significantly degraded. In addition, even if the liquid crystal cell is irradiated with the backlight immediately after driving, electric charge is accumulated, causing an afterimage even in a short period of time, and flickering during driving. occur.

A liquid crystal aligning agent containing a specific diamine and an aliphatic tetracarboxylic acid derivative is used as a liquid crystal aligning agent having excellent voltage holding ratio and reduced charge accumulation when used in such a lateral electric field type liquid crystal display device. disclosed (see Patent Document 1). In addition, as a method for shortening the time until the afterimage disappears, a liquid crystal alignment film with a specific low volume resistivity (see Patent Document 2) or an alignment film whose volume resistivity is difficult to change even with the backlight of the liquid crystal display element is proposed (see Patent Document 3). However, as the performance of liquid crystal display devices has improved, the characteristics required of liquid crystal alignment films have become more stringent, and it is difficult to sufficiently satisfy all the required characteristics with these conventional techniques.

International publication WO2004/021076 pamphlet International publication WO2004/053583 pamphlet International publication WO2013/008822 pamphlet

The present invention provides a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element that can obtain a liquid crystal aligning film that is excellent in voltage holding ratio, quickly relieves accumulated charges, and hardly causes flickering during driving. The challenge is to

As a result of intensive studies to solve the above problems, the present inventors have found that various properties can be improved at the same time by introducing a specific structure into the polymer contained in the liquid crystal aligning agent. completed the invention.

但し、式（１）中、Ｒ^１は水素又は炭素数１～３のアルキル基を表し、式（２）中、Ｒ^２は単結合又は２価の有機基であり、Ｒ^３は－（ＣＨ_２）_ｎ－で表される構造であり（但し、ｎは２～２０の整数であり、任意の－ＣＨ_２－はそれぞれ隣り合わない条件でエーテル、エステル、アミド、ウレア及びカルバメートから選ばれる結合に置き換えられてもよく、該アミド及びウレアの水素原子はメチル基、又はｔｅｒｔ－ブトキシカルボニル基に置き換えられてもよい。）、Ｒ^４は単結合又は２価の有機基であり、ベンゼン環上の任意の水素原子は１価の有機基で置き換えられてもよい。The gist of the present invention is as follows.
1. A liquid crystal aligning agent comprising a polymer (A) having a structure represented by the following formula (1) and a polymer (B) having a structure represented by the following formula (2).

However, in formula (1), R ¹ represents hydrogen or an alkyl group having 1 to 3 carbon atoms; in formula (2), R ² is a single bond or a divalent organic group, and R ³ is —(CH ₂ ) A structure represented by _n- (where n is an integer of 2 to 20, and any -CH ₂ - is a bond selected from ether, ester, amide, urea and carbamate under the condition that they are not adjacent to each other) and the hydrogen atom of the amide and urea may be replaced by a methyl group or a tert-butoxycarbonyl group.), R ⁴ is a single bond or a divalent organic group, and on the benzene ring Any hydrogen atom of may be replaced with a monovalent organic group.

2. The polymer (A) is a polyimide precursor (A) which is a polycondensation product of a diamine having a structure represented by the formula (1) and a tetracarboxylic dianhydride and a polyimide (A) which is an imidized product thereof 2. The liquid crystal aligning agent according to 1 above, which is at least one polymer selected from the group consisting of ).
3. The polymer (B) is a polyimide precursor (B) that is a polycondensation product of a diamine and a tetracarboxylic dianhydride having a structure represented by the formula (2), and a polyimide (B) that is an imidized product thereof 2. The liquid crystal aligning agent according to 1 above, which is at least one polymer selected from the group consisting of ).

但し、式（３）中、Ｘ_１はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ_１は式（１）の構造を含むジアミンに由来する２価の有機基であり、Ｒ_１０は水素原子又は炭素数１～５のアルキル基である。
５．前記式（３）において、Ｙ_１が下記のいずれかの式で表される前記４に記載の液晶配向剤。

６．前記式（３）で表される構造単位を有する重合体が、液晶配向剤に含有される全重合体に対して１０モル％以上含有される前記４又は５に記載の液晶配向剤。4. 4. The liquid crystal aligning agent according to 1 to 3 above, wherein the polyimide precursor (A) has a structural unit represented by the following formula (3).

However, in formula (3), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine containing the structure of formula (1), and R ₁₀ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
5. 4. The liquid crystal aligning agent according to 4 above, wherein in formula (3), Y ₁ is represented by any one of the following formulas.

6. 6. The liquid crystal aligning agent according to 4 or 5 above, wherein the polymer having the structural unit represented by the formula (3) is contained in an amount of 10 mol % or more based on the total polymer contained in the liquid crystal aligning agent.

但し、式（５）中、Ｘ_３はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ_３は式（２）の構造を含むジアミンに由来する２価の有機基であり、Ｒ^１３は水素原子又は炭素数１～５のアルキル基である。
８．前記重合体（Ａ）と前記重合体（Ｂ）の合計量に対して、前記重合体（Ａ）の含有量が、１０～９５質量％であり、前記重合体（Ｂ）の含有量が、５～９０質量％である前記１～７のいずれか１項に記載の液晶配向剤。
９．前記重合体（Ａ）及び前記重合体（Ｂ）を溶解する有機溶媒を含有する前記１～８のいずれか１項に記載の液晶配向剤。
１０．前記１～９のいずれか１項に記載の液晶配向剤から得られる液晶配向膜。
１１．前記１０に記載の液晶配向膜を具備する液晶表示素子。
１２．液晶表示素子が横電界駆動方式である前記１１に記載の液晶表示素子。
１３．液晶表示素子がＦＦＳ方式である前記１１又は１２に記載の液晶表示素子。7. 7. The liquid crystal aligning agent as described in 1 to 6 above, wherein the polyimide precursor (B) has a structural unit represented by the following formula (5).

However, in formula (5), X ₃ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₃ is a divalent organic group derived from a diamine containing the structure of formula (2), and R ¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
8. With respect to the total amount of the polymer (A) and the polymer (B), the content of the polymer (A) is 10 to 95% by mass, and the content of the polymer (B) is 8. The liquid crystal aligning agent according to any one of 1 to 7 above, which is 5 to 90% by mass.
9. 9. The liquid crystal aligning agent according to any one of 1 to 8 above, which contains an organic solvent that dissolves the polymer (A) and the polymer (B).
10. A liquid crystal alignment film obtained from the liquid crystal alignment agent according to any one of 1 to 9 above.
11. 11. A liquid crystal display device comprising the liquid crystal alignment film as described in 10 above.
12. 12. The liquid crystal display element as described in 11 above, wherein the liquid crystal display element is of a lateral electric field drive system.
13. 13. The liquid crystal display element as described in 11 or 12 above, which is an FFS type liquid crystal display element.

By using the liquid crystal aligning agent of the present invention, it is possible to provide a liquid crystal aligning film in which accumulated charges are quickly relieved and flicker hardly occurs during driving, and a liquid crystal display element having excellent display characteristics. Although it is not clear why the present invention can obtain the above characteristics, it is generally considered as follows. The structure of said (1) which the polymer contained in the liquid crystal aligning agent of this invention has has a conjugated structure. Thereby, for example, in the liquid crystal alignment film, it is possible to promote the movement of electric charges, and it is possible to promote the relaxation of accumulated electric charges.

The liquid crystal aligning agent of the present invention is characterized by containing a specific polymer (A) having a structure represented by the above formula (1) and a specific polymer (B) having a structure of the above formula (2). and
The content of the specific polymer (A) is 10 to 95% by mass of the specific polymer (A) with respect to the total amount of the specific polymer (A) and the specific polymer (B), more preferably 60 ~90% by weight. Further, the content of the specific polymer (B) is 90 to 5% by mass, more preferably 40 to 10% by mass, based on the total amount of the specific polymer (A) and the specific polymer (B). be. If the amount of the specific polymer (A) is too small, the charge storage characteristics and rubbing resistance of the liquid crystal alignment film will be deteriorated, and if the amount of the specific polymer (B) is too small, the liquid crystal orientation and orientation control force will be deteriorated. Each of the specific polymer (A) and the specific polymer (B) contained in the liquid crystal aligning agent of the present invention may be one type or two or more types.

<Specific polymer (A)>
The specific polymer (A) is a polymer having a structure represented by formula (1) above.
R ¹ in formula (1) is preferably an alkyl group having 1 to 3 carbon atoms from the viewpoint of the solubility of the resulting polymer, and is preferably a methyl group from the viewpoint of not impairing liquid crystal orientation.

In the above formula (1), one or more arbitrary hydrogen atoms on the benzene ring may be substituted with a monovalent organic group other than a primary amino group. Examples of the monovalent organic group include alkyl groups having 1 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, fluorine-containing alkyl groups having 1 to 20 carbon atoms, and 2 carbon atoms. to 20 fluorine-containing alkenyl groups, fluorine-containing alkoxy groups having 1 to 20 carbon atoms, cyclohexyl groups, phenyl groups, groups composed of fluorine atoms or combinations thereof. From the viewpoint of liquid crystal orientation, alkyl groups having 1 to 4 carbon atoms, alkenyl groups having 2 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, fluorine-containing alkyl groups having 1 to 4 carbon atoms, and 2 carbon atoms. A monovalent organic group selected from the group consisting of a fluorine-containing alkenyl group having 1 to 4 carbon atoms and a fluorine-containing alkoxy group having 1 to 4 carbon atoms is preferred. A more preferable structure of the above formula (1) is one in which hydrogen atoms on the benzene ring are unsubstituted.

As the specific polymer (A) in the present invention, a polymer obtained using a diamine having a structure represented by the above formula (1) is preferred. Specific examples of such polymers include polyamic acids, polyamic acid esters, polyimides, polyureas, and polyamides. From the viewpoint of use as a liquid crystal aligning agent, among others, the specific polymer (A) is a polyimide precursor having a structural unit represented by the following formula (3), and at least one polyimide which is an imidized product thereof. Seeds are preferred.

但し、式（３）において、Ｘ_１はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ_１は式（１）の構造を含むジアミンに由来する２価の有機基であり、Ｒ^１０は水素原子又は炭素数１～５のアルキル基である。Ｒ^１０は、加熱によるイミド化のしやすさの点から、水素原子、メチル基又はエチル基が好ましい。

However, in formula (3), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine containing the structure of formula (1), and R ¹⁰ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ¹⁰ is preferably a hydrogen atom, a methyl group or an ethyl group from the viewpoint of ease of imidization by heating.

The polyimide precursor (A) is a polymer obtained by a polycondensation reaction between a diamine having a structure represented by the above formula (1) and a tetracarboxylic acid derivative, and X ₁ in formula (3) is the tetra It is a tetravalent organic group derived from a carboxylic acid derivative. This tetracarboxylic acid derivative, preferably tetracarboxylic dianhydride, has solubility in a polymer solvent, applicability of a liquid crystal aligning agent, liquid crystal alignment when used as a liquid crystal alignment film, voltage holding ratio, accumulated charge. etc., depending on the degree of properties required, and one type or two or more types may be mixed in the same polymer.

Specific examples of X ₁ in formula (3) include structures of formulas (X-1) to (X-46) listed on pages 13 to 14 of International Publication 2015/119168. .
Preferred structures of X ₁ (A-1) to (A-21) are shown below, but the present invention is not limited thereto.

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

Specific examples of Y ₁ in formula (3) include the structure of formula (1) above. The diamine having the structure of formula (1) is described in Japanese Patent Application Laid-Open No. 2009-75140, and can be produced by the production method described in the same publication.

The specific polymer (A) in the present invention contains at least one structural unit selected from structural units represented by the above formula (3) and structural units obtained by imidizing the same, and the entire structure of the specific polymer (A). It is preferably contained in an amount of 5 to 100 mol%, more preferably 10 to 100 mol%, more preferably 20 to 100 mol%, from the viewpoint of achieving both liquid crystal orientation and relaxation properties of accumulated charges. is more preferred.
The specific polymer (A) has, in addition to the structural unit represented by formula (3), a structural unit represented by the following formula (4) and/or a structural unit obtained by imidizing it. may

式（４）において、Ｘ_２はテトラカルボン酸誘導体に由来する４価の有機基であり、Ｙ_２は式（１）の構造を主鎖方向に含まないジアミンに由来する２価の有機基であり、Ｒ^１１は、前記式（３）のＲ^１０の定義と同じであり、Ｒ^１２は水素原子又は炭素数１～４のアルキル基を表す。また、２つあるＲ^１２の少なくとも一方は水素原子であることが好ましい。

In formula (4), X2 is a tetravalent organic group derived from a tetracarboxylic _acid derivative, and Y2 is a _divalent organic group derived from a diamine that does not contain the structure of formula (1) in the main chain direction. and R ¹¹ has the same definition as R ¹⁰ in formula (3) above, and R ¹² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. At least one of the two R ¹² is preferably a hydrogen atom.

Specific examples of X ₂ include those exemplified for X ₁ in formula (3), including preferred examples. Y2 is a _divalent organic group derived from a diamine that does not contain the structure of formula (1) in the main chain direction, and its structure is not particularly limited. In addition, Y ₂ depends on the degree of required characteristics such as the solubility of the polymer in the solvent, the applicability of the liquid crystal alignment agent, the alignment of the liquid crystal when used as a liquid crystal alignment film, the voltage holding ratio, and the accumulated charge. , and may be one type or a mixture of two or more types in the same polymer.

Specific examples of Y ₂ include the structure of formula (2) published on page 4 of International Publication WO 2015/119168, and the formulas (Y-1) to ( Y-97), structures of (Y-101) to (Y-118); a divalent organic group obtained by removing two amino groups from formula (2), published on page 6 of WO 2013/008906 ; Divalent organic group with two amino groups removed from formula (1) published on page 8 of International Publication 2015/122413; Formula (3) published on page 8 of International Publication 2015/060360 Structure; Divalent organic group obtained by removing two amino groups from Formula (1) described on page 8 of Japanese Patent Publication 2012-173514; Formula ( Examples include divalent organic groups obtained by removing two amino groups from A) to (F).

Preferred structures of Y2 _are shown below, but the present invention is not limited thereto.

Among the structures of Y ₂ , (B-28) and (B-29) are particularly preferable from the viewpoint of further improving rubbing resistance, and (B-1) to (B-3) are liquid crystal alignment properties. Particularly preferable from the viewpoint of further improvement, (B-14) to (B-18) and (B-27) are particularly preferable from the viewpoint of further improving the relaxation rate of accumulated charges, and (B-26) is This is preferable from the viewpoint of further improving the voltage holding ratio.

When the specific polymer (A) has a structural unit represented by formula (3) and a structural unit represented by formula (4), the structural unit represented by formula (3) is represented by formula (3 ) and formula (4) is preferably 10 mol % or more, more preferably 20 mol % or more, and particularly preferably 30 mol % or more.
The molecular weight of the polyimide precursor constituting the specific polymer (A) in the present invention is preferably 2,000 to 500,000, more preferably 5,000 to 300,000 in weight average molecular weight, and more preferably 10,000 to 100,000.

The polyimide constituting the specific polymer (A) is obtained by ring-closing a polyimide precursor having a structural unit represented by formula (3) and, if necessary, a structural unit represented by formula (4). In this polyimide, the ring closure rate (also referred to as imidization rate) of amic acid groups does not necessarily need to be 100%, and can be arbitrarily adjusted according to the application and purpose.
Examples of the method for imidizing the polyimide precursor include thermal imidization in which the solution of the polyimide precursor is heated as it is, and catalytic imidization in which a catalyst is added to the solution of the polyimide precursor.

但し、式（２）中、Ｒ^２は単結合又は２価の有機基であり、単結合が好ましい。Ｒ^３は－（ＣＨ_２）_ｎ－で表される構造である。ｎは２～１０の整数であり、３～７が好ましい。また、任意の－ＣＨ_２－はそれぞれ隣り合わない条件でエーテル、エステル、アミド、ウレア、又はカルバメート結合に置き換えられてもよく、該アミド及びウレアの水素原子はメチル基、又はｔｅｒｔ－ブトキシカルボニル基に置き換えられてもよい。Ｒ^４は単結合又は２価の有機基である。ベンゼン環上の任意の水素原子は１価の有機基で置き換えられてもよく、置換基は、フッ素原子又はメチル基が好ましい。<Specific polymer (B)>
The specific polymer (B) contained in the liquid crystal aligning agent of the present invention is a polymer having the structure of formula (2) below.

However, in formula (2), ^R2 is a single bond or a divalent organic group, preferably a single bond. R ³ is a structure represented by —(CH ₂ ) _n —. n is an integer of 2-10, preferably 3-7. Any —CH ₂ — may be replaced with an ether, ester, amide, urea, or carbamate bond under the condition that they are not adjacent to each other, and the hydrogen atom of the amide and urea is a methyl group or a tert-butoxycarbonyl group. may be replaced by ^R4 is a single bond or a divalent organic group. Any hydrogen atom on the benzene ring may be replaced with a monovalent organic group, and the substituent is preferably a fluorine atom or a methyl group.

Specific examples of the structure represented by formula (2) include, but are not limited to, the following.

但し、式（５）中、Ｘ^３はテトラカルボン酸誘導体に由来する４価の有機基である。具体的には、下記式（Ｘ１－１）～（Ｘ１－４５）で表される構造からなる群から選ばれる少なくとも１種類が好ましい。As the specific polymer (B) in the present invention, a polymer obtained using a diamine having a structure represented by the above formula (2) is preferred. Specific examples of the polymer include polyamic acid, polyamic acid ester, polyimide, polyurea, and polyamide. From the viewpoint of use as a liquid crystal aligning agent, the specific polymer (B) is, among others, a polyimide precursor containing a structural unit represented by the following formula (5), and at least one polyimide which is an imidized product thereof. Seeds are preferred.

However, in formula ( ⁵ ), X3 is a tetravalent organic group derived from a tetracarboxylic acid derivative. Specifically, at least one type selected from the group consisting of structures represented by the following formulas (X1-1) to (X1-45) is preferable.

In formula (X1-1), R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group or a phenyl group; From the viewpoint of liquid crystal orientation, R ⁵ , R ⁶ , R ⁷ and R ⁸ are preferably a hydrogen atom, a halogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom or a methyl group.

Among these, X ³ is preferably (X1-10), (X1-11), or (X1-29) from the viewpoint of liquid crystal orientation and reliability, and (X1-10) or (X1-11 ) is more preferred.

In formula (5), Y3 is a divalent organic group derived from a diamine containing the structure of formula ( ₂ ), and from the viewpoint of orientation, in formula (2), ^R4 is a single bond or a benzene ring. A divalent organic group derived from a certain diamine is preferred. R ¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and is particularly preferably a hydrogen atom or a methyl group from the viewpoint of ease of imidization by heating.

In the specific polymer (B) in the present invention, the ratio of at least one structural unit selected from structural units represented by the above formula (5) and structural units imidized thereof is It preferably contains 20 to 100 mol%, more preferably 30 to 70 mol%, more preferably 50 to 70 mol%, from the viewpoint of achieving both liquid crystal orientation and reliability. is more preferred.

但し、式（６）において、Ｒ^１４は、前記式（５）のＲ^１３の定義と同じである。Ｘ_４はテトラカルボン酸誘導体に由来する４価の有機基であり、その構造は特に限定されない。具体的例を挙げるならば、上記式（Ｘ１－１）～（Ｘ－４５）の構造が挙げられる。The specific polymer (B) in the present invention is, in addition to the structural unit represented by the above formula (5), a structural unit represented by the following formula (6) and / or an imidized structural unit thereof may have

However, in formula (6), R ¹⁴ has the same definition as R ¹³ in formula (5). X4 is a _tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. Specific examples include the structures of the above formulas (X1-1) to (X-45).

In the above formula ( ₆ ), Y4 is a divalent organic group derived from diamine, and its structure is not particularly limited. Specific examples of Y ₄ include structures represented by the following formulas (Y-1) to (Y-138).

In the specific polymer (A) and the specific polymer (B), the ratio of structural units imidized to the structural units of the polyimide precursor contained in each (also referred to as imidization ratio) is It can be arbitrarily adjusted according to the properties of the liquid crystal aligning agent. From the viewpoint of solubility and charge storage properties, the imidization rate in the specific polymer (A) is preferably 0 to 55%, more preferably 0 to 20%. Further, from the viewpoint of liquid crystal alignment, alignment control force, and voltage holding ratio, the imidization rate in the specific polymer (B) is preferably high, preferably 40 to 95%, more preferably 55 to 90%. is.

<Method for producing polyamic acid ester>
A polyamic acid ester, which is a polyimide precursor used in the present invention, can be synthesized by the following method (1), (2) or (3).
(1) Synthesis from polyamic acid A polyamic acid ester can be synthesized by esterifying a polyamic acid obtained from a tetracarboxylic dianhydride and a diamine.
Specifically, a polyamic acid and an esterifying agent are reacted in the presence of an organic solvent at -20°C to 150°C, preferably 0°C to 50°C, for 30 minutes to 24 hours, preferably 1 to 4 hours. Can be synthesized.
As the esterifying agent, those that can be easily removed by purification are preferable, and include N,N-dimethylformamide dimethyl acetal, N,N-dimethylformamide diethyl acetal, N,N-dimethylformamide dipropyl acetal, and N,N-dimethylformamide. Dineopentyl butyl acetal, N,N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazene, 1-ethyl-3-p-tolyltriazene, 1-propyl-3-p -tolyltriazene, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride and the like. The amount of the esterifying agent to be added is preferably 2 to 6 molar equivalents per 1 mol of repeating units of the polyamic acid.
The solvent used in the above reaction is preferably N,N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone in view of the solubility of the polymer, and these may be used singly or in combination of two or more. good. The concentration during synthesis is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, from the viewpoints that precipitation of the polymer hardly occurs and that a high molecular weight product is easily obtained.

(2) Synthesis by reaction of tetracarboxylic acid diester dichloride and diamine Polyamic acid ester can be synthesized from tetracarboxylic acid diester dichloride and diamine.
Specifically, a tetracarboxylic acid diester dichloride and a diamine are mixed in the presence of a base and an organic solvent at -20°C to 150°C, preferably 0°C to 50°C, for 30 minutes to 24 hours, preferably 1 to 4 hours. It can be synthesized by reacting.
Pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used as the base, but pyridine is preferred because the reaction proceeds moderately. The amount of the base to be added is preferably 2 to 4 times the molar amount of the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.
The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone in terms of solubility of the monomer and polymer, and these may be used alone or in combination of two or more. The polymer concentration during synthesis is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, from the viewpoints that precipitation of the polymer hardly occurs and that a high molecular weight product is easily obtained. In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used in the synthesis of the polyamic acid ester is preferably dehydrated as much as possible, and is preferably kept in a nitrogen atmosphere to prevent contamination with outside air.

(3) Synthesis from tetracarboxylic acid diester and diamine Polyamic acid ester can be synthesized by polycondensation of tetracarboxylic acid diester and diamine.
Specifically, a tetracarboxylic acid diester and a diamine are mixed in the presence of a condensing agent, a base, and an organic solvent at 0° C. to 150° C., preferably 0° C. to 100° C., for 30 minutes to 24 hours, preferably 3 to 15 hours. It can be synthesized by time reaction.
The condensing agent includes triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N,N'-carbonyldiimidazole, dimethoxy-1,3,5-triazide Nylmethylmorpholinium, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium Tetrafluoroborate, O-(benzotriazol-1-yl)-N,N , N′,N′-tetramethyluronium hexafluorophosphate, diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate and the like can be used. The amount of the condensing agent to be added is preferably 2 to 3 times the molar amount of the tetracarboxylic acid diester.
Tertiary amines such as pyridine and triethylamine can be used as the base. The amount of the base to be added is preferably 2 to 4 times the molar amount of the diamine component from the viewpoint of easy removal and high molecular weight.
Moreover, in the above reaction, the reaction proceeds efficiently by adding a Lewis acid as an additive. Preferred Lewis acids are lithium halides such as lithium chloride and lithium bromide. The amount of the Lewis acid to be added is preferably 0 to 1.0 times the molar amount of the diamine component.

Among the above three methods for synthesizing polyamic acid esters, the synthesis method (1) or (2) is particularly preferable because it yields a polyamic acid ester having a high molecular weight.
The solution of the polyamic acid ester obtained as described above is poured into a poor solvent while stirring well to precipitate the polymer. Precipitation is carried out several times, washed with a poor solvent, and dried at room temperature or by heating to obtain a purified polyamic acid ester powder. Poor solvents include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Synthesis of polyamic acid>
When the polyamic acid, which is a polyimide precursor in the specific polymer (A) and the specific polymer (B), is obtained by the reaction of a tetracarboxylic dianhydride and a diamine, the tetracarboxylic dianhydride is used in an organic solvent. A method of mixing and reacting the substance and the diamine is preferred.

The organic solvent used in the above reaction is not particularly limited as long as it dissolves the polyamic acid produced. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, Examples include N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone and the like. These may be used alone or in combination. Furthermore, even a solvent that does not dissolve the polyamic acid may be mixed with the above solvent and used as long as the generated polyamic acid does not precipitate. Moreover, the water content in the organic solvent inhibits the polymerization reaction and causes hydrolysis of the formed polyamic acid. Therefore, it is preferable to use an organic solvent that has been dehydrated and dried as much as possible.

As a method for mixing the tetracarboxylic dianhydride component and the diamine component in an organic solvent, a solution obtained by dispersing or dissolving the diamine component in an organic solvent is stirred, and the tetracarboxylic dianhydride component is mixed as it is or in an organic solvent. A method of adding by dispersing or dissolving in a solvent, conversely, a method of adding a diamine component to a solution in which a tetracarboxylic dianhydride component is dispersed or dissolved in an organic solvent, and a method of adding a tetracarboxylic dianhydride component and a diamine component. A method of alternately adding them may be mentioned, and any of these methods may be used in the present invention. Moreover, when the tetracarboxylic dianhydride component or the diamine component consists of multiple types of compounds, these multiple types of components may be reacted in a state of being mixed in advance, or may be individually reacted sequentially.

The temperature at which the tetracarboxylic dianhydride component and the diamine component are reacted in an organic solvent is usually 0 to 150°C, preferably 5 to 100°C, more preferably 10 to 80°C. The higher the temperature, the earlier the polymerization reaction will be completed. In addition, the reaction can be carried out at any concentration, but if the concentration is too low, it becomes difficult to obtain a high-molecular-weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high, making uniform stirring difficult. Therefore, it is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The initial stage of the reaction may be carried out at a high concentration, and then the organic solvent may be added.

The molar ratio of the tetracarboxylic dianhydride component to the diamine component used in the polyamic acid polymerization reaction is preferably 1:0.8 to 1.2. Polyamic acid obtained by adding an excessive amount of the diamine component may result in increased coloration of the solution. As in ordinary polycondensation reactions, the closer this molar ratio is to 1:1, the greater the molecular weight of the resulting polyamic acid. If the molecular weight of the polyamic acid is too small, the strength of the coating film obtained therefrom may be insufficient. If it becomes too thick, the workability in forming the coating film and the uniformity of the coating film may be deteriorated. Therefore, the polyamic acid used in the liquid crystal aligning agent of the present invention preferably has a reduced viscosity (concentration of 0.5 dl/g, 30° C. in NMP) of 0.1 to 2.0, more preferably 0.2 to 1.5. .

When the liquid crystal aligning agent of the present invention does not want to contain the solvent used for polymerization of the polyamic acid, or when unreacted monomer components or impurities are present in the reaction solution, this precipitation recovery and purification are performed. As for the method, it is preferable to put the polyamic acid solution into a poor solvent that is being stirred and collect the precipitate. The poor solvent used for precipitating and recovering the polyamic acid is not particularly limited, but examples thereof include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene. The polyamic acid precipitated by putting it into the poor solvent can be recovered by filtering and washing, and then dried at room temperature or under heat under normal pressure or reduced pressure to obtain a powder. Polyamic acid can be purified by further dissolving this powder in a good solvent and repeating the reprecipitation operation 2 to 10 times. This purification step is preferably carried out when impurities cannot be completely removed by a single precipitation recovery operation. It is preferable to use three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons as the poor solvent in this case, because the purification efficiency is further improved.

<Method for producing polyimide>
The polyimide in the specific polymer (A) and the specific polymer (B) can be produced by imidating the polyamic acid ester or polyamic acid, which are polyimide precursors.
When producing a polyimide from a polyamic acid ester, chemical imidization by adding a basic catalyst to the polyamic acid solution obtained by dissolving the polyamic acid ester solution or the polyamic acid ester resin powder in an organic solvent is convenient. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is less likely to decrease during the imidization process.

When producing a polyimide from a polyamic acid, chemical imidization by adding a catalyst to the solution of the polyamic acid obtained by the reaction of the diamine component and the tetracarboxylic dianhydride is convenient. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is less likely to decrease during the imidization process.

Chemical imidization can be carried out by stirring a polymer to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, the solvent used in the polymerization reaction described above can be used. Basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Among them, pyridine is preferable because it has an appropriate basicity for advancing the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Among them, acetic anhydride is preferred because it facilitates purification after the reaction is completed.

The imidization reaction temperature is -20°C to 140°C, preferably 0°C to 100°C, and the reaction time is 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 times the molar amount of the amic acid group, preferably 2 to 20 times the molar amount, and the amount of the acid anhydride is 1 to 50 times the molar amount of the amic acid group, preferably 3 to 30 times the molar amount. Double. The imidization rate of the resulting polymer can be controlled by adjusting the catalyst amount, temperature and reaction time.
Since the added catalyst and the like remain in the solution after the imidization reaction of the polyamic acid ester or polyamic acid, the resulting imidized polymer is recovered by the means described below and redissolved in an organic solvent. It is preferable to set it as the liquid crystal aligning agent of this invention.

The polyimide solution obtained as described above is poured into a poor solvent while stirring well to precipitate a polymer. Precipitation is carried out several times, washed with a poor solvent, and dried at room temperature or by heating to obtain a purified polyamic acid ester powder.
The poor solvent is not particularly limited, but examples include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention contains the specific polymer (A) and the specific polymer (B). Each of the specific polymer (A) and the specific polymer (B) contained in the liquid crystal aligning agent of the present invention may be one type or two or more types.
Further, in addition to the specific polymers (A) and (B), other polymers, that is, the divalent group represented by the formula (1) and the divalent group represented by the formula (2) It may contain a polymer that does not have Such other polymers include polyamic acids, polyimides, polyamic acid esters, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene or derivatives thereof, poly(styrene-phenylmaleimide) derivatives, poly(meth) Acrylate and the like can be mentioned.
When the liquid crystal aligning agent of the present invention contains other polymers, the total content of the specific polymer (A) and the specific polymer (B) in the total polymer components is preferably 5% by mass or more, An example thereof is 5 to 95% by mass.

From the viewpoint of forming a uniform thin film, the liquid crystal aligning agent preferably takes the form of a coating liquid, and is preferably a coating liquid containing a polymer component and an organic solvent for dissolving the polymer component. At that time, the content (concentration) of the polymer in the liquid crystal aligning agent can be appropriately changed by setting the thickness of the coating film to be formed. From the viewpoint of forming a uniform and defect-free coating film, it is preferably 1% by mass or more, and from the viewpoint of the storage stability of the solution, it is preferably 10% by mass or less. A particularly preferred polymer content is 2 to 8% by mass.

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

In addition, the organic solvent contained in the liquid crystal aligning agent can be a mixed solvent in which a solvent that improves the coatability and the surface smoothness of the coating film when applying the liquid crystal aligning agent in addition to the above solvents can be used. It is common, and such a mixed solvent is suitably used also in the liquid crystal aligning agent of this invention. Specific examples of the organic solvent to be used in combination are listed below, but are not limited to these examples.

式［Ｄ－１］中、Ｄ^１は炭素数１～３のアルキル基を示し、式［Ｄ－２］中、Ｄ^２は炭素数１～３のアルキル基を示し、式［Ｄ－３］中、Ｄ^３は炭素数１～４のアルキル基を示す。For example, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentyl alcohol, tert-pentyl alcohol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol , 2-heptanol, 3-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 2,6- dimethyl-4-heptanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2, 3-butanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, diisopropyl ether, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene Glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2- Pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 2,6-dimethyl-4-heptanone, 4,6-dimethyl-2-heptanone, 3-ethoxybutylacetate, 1-methylpentylacetate tart, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2-(methoxymethoxy)ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2-(hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(butoxyethoxy)propanol, propylene glycol monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoethyl ether Propylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate , diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, acetic acid Ethyl, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate , 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, lactic acid methyl ester, lactic acid ethyl ester, lactic acid n-propyl ester, lactic acid n-butyl ester, lactic acid isoamyl ester , and solvents represented by the following formulas [D-1] to [D-3].

In formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms, in formula [D-2], D ² represents an alkyl group having 1 to 3 carbon atoms, and formula [D-3] Among them, D3 represents an alkyl group having 1 to ⁴ carbon atoms.

Among them, preferred combinations of solvents include N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2- pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether Butyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2 ,6-dimethyl-4-heptanol, N-methyl-2-pyrrolidone, γ-butyrolactone and dipropylene glycol dimethyl ether. The kind and content of such a solvent are appropriately selected according to the liquid crystal aligning agent coating device, coating conditions, coating environment, and the like.

Additives such as a silane coupling agent may be added to the liquid crystal aligning agent of the present invention in order to improve the adhesion of the coating film to the substrate, and other resin components may be added.

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

Moreover, the following additives may be added to the liquid crystal aligning agent of the present invention in order to increase the mechanical strength of the film.

These additives are preferably 0.1 to 30 parts by weight per 100 parts by weight of the polymer component contained in the liquid crystal aligning agent. If the amount is less than 0.1 parts by mass, no effect can be expected, and if the amount exceeds 30 parts by mass, the orientation of the liquid crystal is lowered.

<Liquid crystal alignment film>
The liquid crystal alignment film of the present invention is obtained from the liquid crystal alignment agent. To give an example of a method of obtaining a liquid crystal alignment film from a liquid crystal alignment agent, a liquid crystal alignment agent in the form of a coating liquid is applied to a substrate, dried, and fired to obtain a film that is subjected to a rubbing treatment method or a photo-alignment treatment method. and a method of performing orientation treatment.

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

The method of applying the liquid crystal aligning agent is not particularly limited, but industrially, screen printing, offset printing, flexographic printing, ink jet method and the like are common. Other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method, and a spray method, and these may be used depending on the purpose.
After the liquid crystal aligning agent is applied onto the substrate, the solvent is evaporated by heating means such as a hot plate, a thermal circulation oven, an IR (infrared) oven, and baked. The drying after applying a liquid crystal aligning agent and a baking process can select arbitrary temperature and time. Usually, in order to sufficiently remove the contained solvent, the conditions include calcination at 50 to 120° C. for 1 to 10 minutes, followed by calcination at 150 to 300° C. for 5 to 120 minutes.

The thickness of the liquid crystal alignment film after baking is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be lowered.
The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for a horizontal electric field liquid crystal display element such as an IPS system or an FFS system, and is particularly useful as a liquid crystal alignment film for an FFS system liquid crystal display element.

<Liquid crystal display element>
The liquid crystal display element of the present invention is obtained by obtaining a substrate with a liquid crystal aligning film obtained from the liquid crystal aligning agent, producing a liquid crystal cell by a known method, and using the liquid crystal cell.
As an example of a method of manufacturing a liquid crystal cell, a liquid crystal display device having a passive matrix structure will be described as an example. A liquid crystal display element having an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion forming an image display may be used.

Specifically, transparent glass substrates are prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be ITO electrodes, for example, and are patterned so as to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrodes and the segment electrodes. The insulating film can be, for example, a film made of SiO ₂ —TiO ₂ formed by a sol-gel method. Next, a liquid crystal alignment film is formed on each substrate under the above conditions.

Next, for example, a UV-curing sealing material was placed at a predetermined location on one of the two substrates on which the liquid crystal alignment film was formed, and liquid crystal was placed at several predetermined locations on the surface of the liquid crystal alignment film. After that, the other substrate is attached and pressed so that the liquid crystal alignment film faces each other, and the liquid crystal is spread to the front surface of the liquid crystal alignment film. get a cell
Alternatively, as a step after the liquid crystal alignment film is formed on the substrates, when a sealing material is placed at a predetermined location on one of the substrates, an opening that can be filled with the liquid crystal from the outside is provided, and the liquid crystal is supplied. After the substrates are bonded together without disposing, a liquid crystal material is injected into the liquid crystal cell through an opening provided in the sealing material, and then the opening is sealed with an adhesive to obtain a liquid crystal cell. The injection of the liquid crystal material may be performed by a vacuum injection method or by a method utilizing capillary action in the air.

In any of the above methods, in order to secure a space for filling the liquid crystal material in the liquid crystal cell, a columnar projection is provided on one of the substrates, spacers are scattered on one of the substrates, or a sealing material is used. It is preferable to take a means such as mixing a spacer into or combining these.

Examples of the liquid crystal material include nematic liquid crystals and smectic liquid crystals. Among them, nematic liquid crystals are preferable, and either positive liquid crystal materials or negative liquid crystal materials may be used. Next, a polarizing plate is installed. Specifically, it is preferable to attach a pair of polarizing plates to the surfaces of the two substrates opposite to the liquid crystal layer.
In addition, as long as the liquid crystal aligning agent of this invention is used, the liquid crystal display element of this invention is not limited to said description, It may be produced by another well-known method. A process for obtaining a liquid crystal display element is disclosed, for example, in Japanese Patent Application Laid-Open No. 2015-135393, page 17, paragraph 0074 to page 19, paragraph 0081.

EXAMPLES The present invention will be specifically described below with reference to examples, etc., but the present invention is not limited to these examples. Abbreviations of compounds and solvents are as follows.
NMP: N-methyl-2-pyrrolidone GBL: γ-butyrolactone
BCS: butyl cellosolve

<Viscosity>
The viscosity of the polymer solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, a cone rotor TE-1 (1°34', R24), and a temperature of 25°C. .

<Measurement of imidization rate>
The imidization rate of polyimide was measured as follows. 30 mg of polyimide powder is placed in an NMR (nuclear magnetic resonance) sample tube (NMR sampling tube standard,
φ5 (manufactured by Kusano Kagaku)), and deuterated dimethyl sulfoxide (DMSO-d6,0.
05 mass % TMS (tetramethylsilane) mixture) (0.53 ml) was added and completely dissolved by applying ultrasonic waves. This solution was subjected to proton NMR at 500 MHz using an NMR spectrometer (JNW-ECA500) (manufactured by JEOL Datum Co., Ltd.). For the imidization rate, a proton derived from a structure that does not change before and after imidization is determined as a reference proton. It was obtained by the following formula using the integrated value.
Imidation rate (%) = (1-α x/y) x 100
In the above formula, x is the proton peak integrated value derived from the NH group of the amic acid, y is the peak integrated value of the reference proton, and α is the N of the amic acid in the case of polyamic acid (imidization rate is 0%).
It is the ratio of the number of standard protons to one H-group proton.

(Synthesis example 1)
54.7 g (224 mmol) of DA-1 and 53.4 g (95.9 mmol) of DA-2 were weighed into a 1 L four-necked flask equipped with a stirring device and a nitrogen inlet tube, 613 g of NMP was added, and nitrogen was added. Dissolve by stirring while feeding. While stirring this diamine solution under water cooling, 89.5 g (298 mmol) of CA-1 was added, and 175 g of NMP was added, and stirred at 23 ° C. for 12 hours under a nitrogen atmosphere to obtain a polyamic acid (viscosity: 890 mPa s). A solution of
900 g of this polyamic acid solution was placed in a 3 L Erlenmeyer flask equipped with a stirrer, 1350 g of NMP, 74.3 g of acetic anhydride and 34.6 g of pyridine were added, stirred at room temperature for 30 minutes, and then stirred at 40°C. It was reacted for 2 hours. This reaction solution was poured into 8300 g of methanol, and the resulting precipitate was filtered off. After washing the precipitate with methanol, it was dried under reduced pressure at a temperature of 60° C. to obtain polyimide powder (imidization rate: 66%).

50.7 g of this polyimide powder was placed in a 500 mL Erlenmeyer flask containing a stirrer, 372 g of NMP was added, and the mixture was stirred at 50° C. for 20 hours to dissolve. Further, 11.9 g of this solution was placed in a 200 mL Erlenmeyer flask containing a stirrer, containing 4.49 g of NMP, 5.86 g of GBL, and 1% by mass of 3-glycidoxypropyltriethoxysilane. 1.19 g of NMP solution and 5.86 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a polyimide solution (SPI-1).

(Synthesis example 2)
86.0 g (352 mmol) of DA-1, 53.4 g (95.9 mmol) of DA-2, and 76.5 g (191 mmol) of DA-3 were added to a 1 L four-necked flask equipped with a stirrer and nitrogen inlet tube. ) was weighed, 1580 g of NMP was added, and dissolved by stirring while sending nitrogen. While stirring this diamine solution under water cooling, 93.2 g (416 mmol) of CA-2 was added, and 168 g of NMP was further added, followed by stirring at 40° C. for 3 hours under a nitrogen atmosphere. Further, 28.2 g (143 mmol) of CA-3 was added, and 160 g of NMP was added, and the mixture was stirred at 23° C. for 4 hours under a nitrogen atmosphere to obtain a polyamic acid solution (viscosity: 200 mPa·s).
800 g of this polyamic acid solution was placed in a 3 L Erlenmeyer flask equipped with a stir bar, 700 g of NMP, 69.7 g of acetic anhydride, and 18.0 g of pyridine were added, stirred at room temperature for 30 minutes, and then heated to 55°C. was reacted for 3 hours. This reaction solution was poured into 5600 g of methanol, and the obtained precipitate was filtered off. After washing the precipitate with methanol, it was dried under reduced pressure at a temperature of 60° C. to obtain polyimide powder (imidization rate: 75%).

20.3 g of this polyimide powder was placed in a 300 mL Erlenmeyer flask equipped with a stirrer, 148 g of NMP was added, and the mixture was dissolved by stirring at 50° C. for 20 hours. Furthermore, 6.31 g of this solution was placed in a 200 mL Erlenmeyer flask containing a stirrer, and an NMP solution containing 2.06 g of NMP, 3.00 g of GBL, and 1% by mass of 3-glycidoxypropyltriethoxysilane was prepared. 0.630 g and 3.00 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a polyimide solution (SPI-2).

(Synthesis Example 3)
93.8 g (384 mmol) of DA-1, 51.0 g (128 mmol) of DA-3, and 43.7 g (128 mmol) of DA-4 were weighed into a 1 L four-necked flask equipped with a stirrer and a nitrogen inlet tube. 1380 g of NMP was added and dissolved by stirring while sending nitrogen. While stirring this diamine solution under water cooling, 93.2 g (416 mmol) of CA-2 was added, 214 g of NMP was further added, and the mixture was stirred at 40° C. for 3 hours under a nitrogen atmosphere. Further, 32.6 g (166 mmol) of CA-3 was added, 185 g of NMP was added, and the mixture was stirred at 23° C. for 4 hours under a nitrogen atmosphere to obtain a polyamic acid solution (viscosity: 200 mPa·s).

700 g of this polyamic acid solution was placed in a 3 L Erlenmeyer flask equipped with a stir bar, 612 g of NMP, 60.4 g of acetic anhydride, and 15.6 g of pyridine were added, stirred at room temperature for 30 minutes, and then heated to 55°C. was reacted for 3 hours. This reaction solution was poured into 4900 g of methanol, and the resulting precipitate was filtered off. After washing the precipitate with methanol, it was dried under reduced pressure at a temperature of 60° C. to obtain polyimide powder (imidization rate: 75%).
18.1 g of this polyimide powder was placed in a 200 mL Erlenmeyer flask containing a stirrer, 132 g of NMP was added, and the mixture was dissolved by stirring at 50° C. for 20 hours. Further, 5.54 g of this solution was taken, 2.09 g of NMP, 2.73 g of GBL, 0.550 g of NMP solution containing 1% by mass of 3-glycidoxypropyltriethoxysilane, and 2.5 g of BCS. 73 g was added and stirred with a magnetic stirrer for 2 hours to obtain a polyimide solution (SPI-3).

(Synthesis Example 4)
6.31 g (16.0 mmol) of DA-5 was weighed into a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 47.6 g of NMP was added, and dissolved by stirring while sending nitrogen. While stirring this diamine solution under water cooling, 1.69 g (8.61 mmol) of CA-3 was added, 10.2 g of NMP was further added, and the mixture was stirred at 23° C. for 3 hours under a nitrogen atmosphere. Furthermore, 1.39 g (6.37 mmol) of CA-4 was added, 10.2 g of NMP was added, and the mixture was stirred at 50° C. for 12 hours under a nitrogen atmosphere to obtain a polyamic acid solution (viscosity: 250 mPa s). .
14.4 g of this polyamic acid solution was placed in a 100 mL Erlenmeyer flask equipped with a stirrer, containing 8.39 g of NMP, 8.08 g of GBL, and 1% by mass of 3-glycidoxypropyltriethoxysilane. 1.44 g of the solution and 8.08 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a polyamic acid solution (PAA-1).

(Synthesis Example 5)
4.41 g (40.7 mmol) of DA-6 and 1.79 g (7.20 mmol) of DA-7 were weighed into a 100 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and 55.8 g of NMP was added. , was dissolved by stirring under nitrogen. While stirring this diamine solution under water cooling, 14.0 g (46.6 mmol) of CA-1 was added, 23.7 g of NMP was further added, and the polyamic acid solution ( Viscosity: 815 mPa·s) was obtained.
30 g of this polyamic acid solution was placed in a 200 mL Erlenmeyer flask equipped with a stirrer, 45 g of NMP, 3.64 g of acetic anhydride and 1.69 g of pyridine were added, stirred at room temperature for 30 minutes, and then stirred at 40°C. The reaction was allowed to proceed for 3 hours. This reaction solution was poured into 300 g of methanol, and the obtained precipitate was filtered off. After washing the precipitate with methanol, it was dried under reduced pressure at a temperature of 60° C. to obtain polyimide powder (imidization rate: 73%).

4.10 g of this polyimide powder was placed in a 100 mL Erlenmeyer flask containing a stirrer, 30.6 g of NMP was added, and the mixture was dissolved by stirring at 50° C. for 20 hours. Further, 6.94 g of this solution was placed in a 100 mL Erlenmeyer flask containing a stirrer, containing 4.09 g of NMP, 3.91 g of GBL, and 1% by mass of 3-glycidoxypropyltriethoxysilane. 0.69 g of NMP solution and 3.91 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a polyimide solution (SPI-4).

(Synthesis Example 6)
7.93 g (20.0 mmol) of DA-8 was weighed into a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 87.0 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 2.23 g (11.4 mmol) of CA-3 was added, 10.0 g of NMP was further added, and the mixture was stirred at 23° C. for 3 hours under a nitrogen atmosphere. Furthermore, 1.74 g (8.00 mmol) of CA-4 was added, 10.1 g of NMP was added, and the mixture was stirred at 50°C for 12 hours under a nitrogen atmosphere to obtain a polyamic acid solution (viscosity: 140 mPa s). .
6.91 g of this polyamic acid solution was placed in a 100 mL Erlenmeyer flask containing a stirrer, containing 1.35 g of NMP, 2.98 g of GBL, and 1% by mass of 3-glycidoxypropyltriethoxysilane. 0.69 g of the solution and 2.98 g of BCS were added and stirred with a magnetic stirrer for 2 hours to obtain a polyamic acid solution (PAA-2).

(Example 1)
2.13 g of the polyimide solution (SPI-1) obtained in Synthesis Example 1 and 8.47 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 4 were weighed into a 50 mL Erlenmeyer flask containing a stirrer. , and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-1).

(Example 2)
2.00 g of the polyimide solution (SPI-2) obtained in Synthesis Example 2 and 8.11 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 4 were weighed into a 50 mL Erlenmeyer flask containing a stirrer. , and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-2).

(Example 3)
2.03 g of the polyimide solution (SPI-3) obtained in Synthesis Example 3 and 8.04 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 4 were weighed into a 50 mL Erlenmeyer flask containing a stirrer. , and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-3).

(Example 4)
5.43 g of the polyimide solution (SPI-1) obtained in Synthesis Example 1 and 5.41 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 4 were weighed into a 50 mL Erlenmeyer flask containing a stirrer. , and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-4).

(Comparative example 1)
2.19 g of the polyimide solution (SPI-4) obtained in Synthesis Example 5 and 8.25 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 4 were weighed into a 50 mL Erlenmeyer flask containing a stirrer. , and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-1).

(Comparative example 2)
2.07 g of the polyimide solution (SPI-1) obtained in Synthesis Example 1 and 9.39 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 6 were weighed into a 50 mL Erlenmeyer flask containing a stirrer. , and stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-2).
(Comparative Example 3)
The polyimide solution (SPI-1) obtained in Synthesis Example 1 was used as a liquid crystal aligning agent (B-3).

A method of manufacturing a liquid crystal cell for evaluating the relaxation property of accumulated charges, flicker property, and liquid crystal orientation will be described below.
A liquid crystal cell having the structure of an FFS liquid crystal display element is manufactured. First, a substrate with electrodes was prepared. The substrate is a glass substrate with a size of 30 mm×35 mm and a thickness of 0.7 mm. An IZO electrode forming a counter electrode is formed on the entire surface of the substrate as a first layer. A SiN (silicon nitride) film formed by a CVD method is formed as a second layer on the counter electrode of the first layer. The SiN film of the second layer has a film thickness of 500 nm and functions as an interlayer insulating film. On the SiN film of the second layer, as the third layer, a comb-shaped pixel electrode formed by patterning an IZO film is arranged to form two pixels, a first pixel and a second pixel. is doing. The size of each pixel is 10 mm long and about 5 mm wide. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer.

The pixel electrode on the third layer has a comb-like shape formed by arranging a plurality of V-shaped electrode elements with a bent central portion. The width of each electrode element in the lateral direction is 3 μm, and the interval between electrode elements is 6 μm. Since the pixel electrode that forms each pixel is configured by arranging a plurality of V-shaped electrode elements with a bent central portion, the shape of each pixel is not rectangular, but the central portion is the same as the electrode element. It has a shape resembling a bold, "ku" that bends at. Each pixel is vertically divided by the curved portion in the center, and has a first region above the curved portion and a second region below the curved portion.
Comparing the first region and the second region of each pixel, the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment film, which will be described later, is used as a reference, in the first region of the pixel, the electrode element of the pixel electrode is formed to form an angle of +10° (clockwise), and in the second region of the pixel, , the electrode elements of the pixel electrode are formed at an angle of −10° (clockwise). That is, in the first region and the second region of each pixel, the direction of the rotational movement (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode within the substrate plane is They are configured to be opposite to each other.

Next, the liquid crystal aligning agents obtained in Examples and Comparative Examples were filtered through a filter having a pore size of 1.0 μm, and then applied to the prepared substrate with electrodes by spin coating. After drying on a hot plate at 80° C. for 2 minutes, baking was performed in a hot air circulating oven at 230° C. for 20 minutes to obtain a polyimide film with a film thickness of 60 nm. This polyimide film is rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, moving speed: 30 mm/sec, indentation length: 0.3 mm, rubbing direction: 10° tilted with respect to the third-layer IZO comb-teeth electrode. After that, it was cleaned by irradiating ultrasonic waves in pure water for 1 minute, and water droplets were removed by blowing air. Then, it dried at 80 degreeC for 15 minutes, and obtained the board|substrate with a liquid crystal aligning film. In addition, a polyimide film was formed in the same manner as described above on a glass substrate having columnar spacers with a height of 4 μm, and an ITO electrode was formed on the back surface as the counter substrate. A substrate with the applied liquid crystal alignment film was obtained. These two substrates with a liquid crystal alignment film are used as one set, and a sealant is printed on the substrate with the liquid crystal injection port left. It was pasted together so that it would be After that, the sealant was cured to produce an empty cell with a cell gap of 4 μm. Liquid crystal MLC-3019 (manufactured by Merck & Co.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS liquid crystal cell. After that, the obtained liquid crystal cell was heated at 120° C. for 1 hour, left overnight at 23° C., and then used for evaluation of liquid crystal orientation.

<Relaxation Characteristics of Accumulated Charge>
The liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal, and the pixel electrode and the counter electrode are shorted to the same potential. The backlight was illuminated, and the angle of the liquid crystal cell was adjusted so that the brightness of the light transmitted through the LED backlight measured on the two polarizing plates was minimized.
Next, while applying a rectangular wave with a frequency of 30 Hz to this liquid crystal cell, the VT characteristic (voltage-transmittance characteristic) was measured at a temperature of 23° C., and an AC voltage at which the relative transmittance was 23% was applied. Calculated. Since this AC voltage corresponds to a region in which the change in luminance with respect to the voltage is large, it is convenient for evaluating the accumulated charge via the luminance.

Next, at a temperature of 23° C., an AC voltage with a relative transmittance of 23% and a rectangular wave with a frequency of 30 Hz were applied for 5 minutes, and then a DC voltage of +1.0 V was superimposed and driven for 30 minutes. After that, the DC voltage was turned off, and only the AC voltage with the relative transmittance of 23% and the rectangular wave with the frequency of 30 Hz was applied for 30 minutes.
The faster the relaxation of the accumulated charges, the faster the charge accumulation in the liquid crystal cell when the DC voltage is superimposed. It was evaluated by the time required to decrease from 23% to 23%. That is, evaluation was performed by defining "good" when the relative transmittance decreased to 23% within 30 minutes, and defining "bad" when the relative decrease rate did not decrease to 23% even after 30 minutes.

<Flicker characteristics>
The liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal, and the pixel electrode and the counter electrode are shorted to the same potential. The backlight was illuminated, and the angle of the liquid crystal cell was adjusted so that the brightness of the light transmitted through the LED backlight measured on the two polarizing plates was minimized.
Next, while applying a rectangular wave with a frequency of 30 Hz to this liquid crystal cell, the VT characteristic (voltage-transmittance characteristic) was measured at a temperature of 23° C., and an AC voltage at which the relative transmittance was 23% was applied. Calculated. Since this AC voltage corresponds to a region in which the change in luminance with respect to voltage is large, it is convenient for evaluating flicker characteristics.

Next, the LED backlight that had been lit at a temperature of 23° C. was once turned off and left in the dark for 72 hours. Then, the LED backlight was turned on again. An alternating voltage with a frequency of 30 Hz was applied to drive the liquid crystal cell for 30 minutes, and the flicker amplitude was tracked. The flicker amplitude is measured by a data acquisition/data logger switch unit 34970A (Agilent Technologies company). The flicker level was calculated by the following formula.
Flicker level (%) = {flicker amplitude/(2 x z)} x 100
In the above formula, z is the value read by the data acquisition/data logger switch unit 34970A when driven by an AC voltage with a frequency of 30 Hz at which the relative transmittance is 23%.
Evaluation of flicker characteristics is "good" when the flicker level is maintained at less than 3% for 30 minutes from the start of lighting of the LED backlight and application of the AC voltage, and the flicker level after 30 minutes. was defined as "defective" when it reached 3% or more.

<Evaluation of liquid crystal orientation>
Using this liquid crystal cell, an AC voltage of 9 VPP was applied at a frequency of 30 Hz in a constant temperature environment of 60° C. for 190 hours. After that, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left at room temperature for one day.
After standing, the liquid crystal cell was placed between two polarizing plates arranged so that the polarizing axes were perpendicular to each other, and the backlight was turned on with no voltage applied so that the brightness of the transmitted light was minimized. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel was the darkest to the angle at which the first region was the darkest was calculated as the angle Δ. Similarly, for the second pixel, the second region and the first region were compared to calculate a similar angle Δ. Then, the average value of the angle Δ values of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell. When the angle Δ of the liquid crystal cell was less than 0.4 degrees, it was defined as "good", and when the angle Δ was 0.4 degrees or more, it was defined as "poor".

(Example 5)
After filtering the liquid crystal aligning agent (A-1) obtained in Example 1 through a filter having a pore size of 1.0 μm, a liquid crystal cell was produced as described above. As a result of evaluating the relaxation property of accumulated electric charges in this liquid crystal cell, the time required for the relative transmittance to decrease to 23% was 8 minutes, which was good.
Next, as a result of evaluating the flicker characteristics of this liquid crystal cell, the flicker level was good at 1%. Further, the liquid crystal orientation of this liquid crystal cell was evaluated, and Δ was 0.21 degrees, which was good.

(Example 6)
Except for using the liquid crystal aligning agent (A-2) obtained in Example 2, the relaxation property of accumulated charges was evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was 4 minutes, which was good.
Next, the flicker property was evaluated in the same manner as in Example 5. As a result, the flicker level was good at 1%. Moreover, as a result of evaluating the liquid crystal orientation by the same method as in Example 5, Δ was 0.06 degrees, which was good.

(Example 7)
Except for using the liquid crystal aligning agent (A-3) obtained in Example 3, the relaxation property of accumulated charges was evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was 4 minutes, which was good.
Next, the flicker property was evaluated in the same manner as in Example 5. As a result, the flicker level was good at 1%. Further, the liquid crystal orientation was evaluated in the same manner as in Example 5, and Δ was 0.05 degrees, which was good.

(Example 8)
Except for using the liquid crystal aligning agent (A-4) obtained in Example 4, the relaxation property of accumulated charges was evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was 26 minutes, which was good.
Next, the flicker property was evaluated in the same manner as in Example 5. As a result, the flicker level was 0.3%, which was good. Moreover, as a result of evaluating the liquid crystal orientation by the same method as in Example 5, Δ was 0.22 degrees, which was good.

(Comparative Example 4)
Except for using the liquid crystal aligning agent (B-1) obtained in Comparative Example 1, the relaxation property of accumulated charges was evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was 26 minutes, which was good.
Next, the flicker property was evaluated in the same manner as in Example 5. As a result, the flicker level was good at 2%. Moreover, as a result of evaluating the liquid crystal orientation by the same method as in Example 5, Δ was 0.63 degrees, which was unsatisfactory.

(Comparative Example 5)
Except for using the liquid crystal aligning agent (B-2) obtained in Comparative Example 2, the relaxation property of accumulated charges was evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was 24 minutes, which was good.
Next, as a result of evaluating flicker characteristics in the same manner as in Example 5, the flicker level was 6%, which was unsatisfactory. Moreover, as a result of evaluating the liquid crystal orientation by the same method as in Example 5, Δ was 0.16 degrees, which was good.

(Comparative Example 6)
Except for using the liquid crystal aligning agent (B-3) obtained in Comparative Example 3, the relaxation property of accumulated charge was evaluated in the same manner as in Example 5. As a result, the relative transmittance was 23 even after 30 minutes. % and was unsatisfactory.
Next, the flicker property was evaluated in the same manner as in Example 5. As a result, the flicker level was 0.7%, which was good. Moreover, as a result of evaluating the liquid crystal orientation by the same method as in Example 5, Δ was 0.11 degrees, which was good.

Table 1 shows the evaluation results of accumulated charge relaxation properties, flicker properties, and liquid crystal orientation when the liquid crystal aligning agents obtained in Examples and Comparative Examples were used.

The liquid crystal aligning agent of the present invention is widely used in liquid crystal display elements of vertical electric field systems such as TN system and VA system, in particular, horizontal electric field systems such as IPS system and FFS system.
In addition, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2016-158014 filed on August 10, 2016 are cited here as disclosure of the specification of the present invention. , is to be incorporated.

Claims (12)

A polymer (A) having a structure represented by the following formula (1) and a polymer (B) having a structure represented by the following formula (2), wherein the polymer (A) and the polymer (B) The content of the polymer (A) is 10 to 95% by mass, and the content of the polymer (B) is 5 to 90% by mass, relative to the total amount of the liquid crystal aligning agent. .

However, in formula (1), R ¹ represents hydrogen or an alkyl group having 1 to 3 carbon atoms; in formula (2), R ² is a single bond or a divalent organic group, and R ³ is —(CH ₂ ) A structure represented by _n- (where n is an integer of 2 to 20, and any -CH ₂ - is a bond selected from ether, ester, amide, urea and carbamate under the condition that they are not adjacent to each other) and the hydrogen atom of the amide and urea may be replaced by a methyl group or a tert-butoxycarbonyl group.), R ⁴ is a single bond or a divalent organic group, and on the benzene ring Any hydrogen atom of may be replaced with a monovalent organic group. The polymer (A) is a polyimide precursor (A) which is a polycondensation product of a diamine having a structure represented by the formula (1) and a tetracarboxylic dianhydride and a polyimide (A) which is an imidized product thereof 2. The liquid crystal aligning agent according to claim 1, which is at least one polymer selected from the group consisting of ). The polymer (B) is a polyimide precursor (B) that is a polycondensation product of a diamine and a tetracarboxylic dianhydride having a structure represented by the formula (2), and a polyimide (B) that is an imidized product thereof 2. The liquid crystal aligning agent according to claim 1, which is at least one polymer selected from the group consisting of ). The liquid crystal aligning agent according to claim 2 , wherein the polyimide precursor (A) has a structural unit represented by the following formula (3).

However, in formula (3), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine containing the structure of formula (1), and R ¹⁰ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. The liquid crystal aligning agent according to claim 4, wherein Y1 is represented by any _one of the following formulas in the formula (3).

The liquid crystal aligning agent according to claim 4 or 5, wherein the polymer having the structural unit represented by formula (3) is contained in an amount of 10 mol% or more relative to the total polymer contained in the liquid crystal aligning agent. The liquid crystal aligning agent according to claim 3 , wherein the polyimide precursor (B) has a structural unit represented by the following formula (5).

However, in formula (5), X ³ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ³ is a divalent organic group derived from a diamine containing the structure of formula (2), and R ¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. The liquid crystal aligning agent according to any one of claims 1 to 7, comprising an organic solvent that dissolves the polymer (A) and the polymer (B). A liquid crystal alignment film obtained from the liquid crystal alignment agent according to any one of claims 1 to 8. A liquid crystal display device comprising the liquid crystal alignment film according to claim 9 . 11. The liquid crystal display element according to claim 10, wherein the liquid crystal display element is of a lateral electric field drive system. 12. The liquid crystal display element according to claim 10, wherein the liquid crystal display element is of the FFS system.