WO2018030489A1 - Liquid crystal aligning agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

Provided are: a liquid crystal aligning agent which enables the achievement of a liquid crystal alignment film that exhibits excellent voltage holding ratio and quick reduction of accumulated charge, while being not susceptible to the occurrence of flicker during driving; a liquid crystal alignment film; and a liquid crystal display element. A liquid crystal aligning agent which contains a polymer (A) having a structure represented by formula (1) and a polymer (B) having a structure represented by formula (2). In formula (1), R¹ represents a hydrogen atom or an alkyl group having 1-3 carbon atoms. In formula (2), R² represents a single bond or a divalent organic group; R³ represents a structure represented by -(CH₂)_n- (wherein n represents an integer of 2-20; an arbitrary -CH₂- may be substituted by a bond selected from among an ether bond, an ester bond, an amide bond, a urea bond and a carbamate bond under such conditions that the substituents are not next to each other; and a hydrogen atom in the amide bond or the urea bond may be substituted by a methyl group or a tert-butoxycarbonyl group); R⁴ represents a single bond or a divalent organic group; and an arbitrary hydrogen atom on the benzene ring may be substituted by a monovalent organic group.

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

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

Liquid crystal display elements are widely used as display units for personal computers, mobile phones, smartphones, televisions and the like. The liquid crystal display element includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that apply an electric field to the liquid crystal layer, an alignment film that controls the alignment of liquid crystal molecules in the liquid crystal layer, A thin film transistor (TFT) for switching an electric signal supplied to the pixel electrode is provided. As a driving method of liquid crystal molecules, a vertical electric field method such as a TN method and a VA method, and a horizontal electric field method such as an IPS method and an FFS method are known. The horizontal electric field method in which an electrode is formed only on one side of the substrate and an electric field is applied in a direction parallel to the substrate is wider than the vertical electric field method in which 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 having viewing angle characteristics and capable of high-quality display.

Although the horizontal electric field type liquid crystal cell is excellent in viewing angle characteristics, since there are few electrode portions formed in the substrate, if the voltage holding ratio is low, a sufficient voltage is not applied to the liquid crystal and the display contrast is lowered. Further, if the stability of the liquid crystal alignment is small, the liquid crystal does not return to the initial state when the liquid crystal is driven for a long time, which causes a decrease in contrast and an afterimage. Therefore, the stability of the liquid crystal alignment is important. Furthermore, static electricity is likely to be accumulated in the liquid crystal cell, and charges are accumulated in the liquid crystal cell even when a positive / negative asymmetric voltage generated by driving is applied, and these accumulated charges affect the display as a disorder of liquid crystal alignment or an afterimage. The display quality of the liquid crystal element is significantly reduced. In addition, charges are accumulated by irradiating the liquid crystal cell with backlight light immediately after driving, and afterimages are generated even during short-time driving, and the size of flicker (flicker) changes during driving. It will 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 horizontal electric field type liquid crystal display element. It is disclosed (see Patent Document 1). As a method for shortening the time until the afterimage disappears, a specific liquid crystal alignment film having a low volume resistivity (see Patent Document 2), or an alignment film in which the volume resistivity is hardly changed by the backlight of the liquid crystal display element. There has been proposed a method of using (see Patent Document 3). However, with the improvement in performance of liquid crystal display elements, the characteristics required for the liquid crystal alignment film are becoming stricter, 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 has an excellent voltage holding ratio, quickly reduces accumulated charges, and is less likely to flicker during driving. This is the issue.

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

The gist of the present invention is as follows.
1. The liquid crystal aligning agent characterized by including the polymer (A) which has a structure represented by following formula (1), and the polymer (B) which has a structure of following formula (2).

In the formula (1), R ¹ represents hydrogen or an alkyl group having 1 to 3 carbon atoms. In the formula (2), R ² represents a single bond or a divalent organic group, and R ³ represents — (CH ₂ ) a structure represented by _n − (wherein n is an integer of 2 to 20, and arbitrary —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, Any hydrogen atom may be replaced with a monovalent organic group.

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

4). 4. The liquid crystal aligning agent according to 1 to 3, 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 1 ₁₀ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
5). 5. The liquid crystal aligning agent according to 4, wherein Y ₁ is represented by any one of the following formulas in the formula (3).

6). 6. The liquid crystal aligning agent according to 4 or 5, 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.

7). 7. The liquid crystal aligning agent according to 1 to 6, 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 3 ¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
8). The content of the polymer (A) is 10 to 95% by mass with respect to the total amount of the polymer (A) and the polymer (B), and the content of the polymer (B) is 8. The liquid crystal aligning agent according to any one of 1 to 7, which is 5 to 90% by mass.
9. 9. The liquid crystal aligning agent according to any one of 1 to 8, comprising an organic solvent that dissolves the polymer (A) and the polymer (B).
10. 10. A liquid crystal alignment film obtained from the liquid crystal aligning 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 horizontal electric field drive system.
13. 13. The liquid crystal display element as described in 11 or 12 above, wherein the liquid crystal display element is an FFS method.

By using the liquid crystal aligning agent of the present invention, it is possible to provide a liquid crystal aligning film in which accumulated charge is quickly relaxed and flicker (flickering) hardly occurs during driving, and a liquid crystal display element having excellent display characteristics. Although it is not clear why the above-mentioned characteristics can be obtained by the present invention, it is generally considered as follows. The above structure (1) of the polymer contained in the liquid crystal aligning agent of the present invention has a conjugated structure. Thereby, for example, in the liquid crystal alignment film, the movement of charges can be promoted, and the relaxation of accumulated charges can be promoted.

The liquid crystal aligning agent of this invention contains the specific polymer (A) which has a structure represented by the said Formula (1), and the specific polymer (B) which has a structure of the said Formula (2), It is characterized by the above-mentioned. 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. 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). is there. When there are too few specific polymers (A), the charge storage characteristic and rubbing tolerance of a liquid crystal aligning film will deteriorate, and when there are too few specific polymers (B), the orientation and alignment control power of liquid crystals will deteriorate. 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 the above formula (1).
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 the 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 the primary amino group. Examples of the monovalent organic group include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a fluorine-containing alkyl group having 1 to 20 carbon atoms, and 2 carbon atoms. And a fluorine-containing alkenyl group having 1 to 20 carbon atoms, a fluorine-containing alkoxy group having 1 to 20 carbon atoms, a cyclohexyl group, a phenyl group, a fluorine atom, or a combination thereof. From the viewpoint of the orientation of the liquid crystal, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a fluorine-containing alkyl group having 1 to 4 carbon atoms, 2 carbon atoms A monovalent organic group selected from the group consisting of 1 to 4 fluorine-containing alkenyl groups and 1 to 4 carbon-containing fluorine-containing alkoxy groups is preferred. As a more preferred structure of the above formula (1), the hydrogen atom on the benzene ring is unsubstituted.

As the specific polymer (A) in the present invention, a polymer obtained by using a diamine having a structure represented by the above formula (1) is preferable. Specific examples of such a polymer include polyamic acid, polyamic acid ester, polyimide, polyurea, polyamide and the like. From the viewpoint of use as a liquid crystal aligning agent, among these, the specific polymer (A) is at least one selected from a polyimide precursor having a structural unit represented by the following formula (3) and a polyimide that is an imidized product thereof. Preferably it is a seed.

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 1 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 easy 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 the formula (3) It is a tetravalent organic group derived from a carboxylic acid derivative. This tetracarboxylic acid derivative, preferably tetracarboxylic dianhydride, is the solubility of the polymer in the solvent, the coating property of the liquid crystal aligning agent, the orientation of the liquid crystal when it is used as a liquid crystal alignment film, the voltage holding ratio, the accumulated charge. For example, one type or two or more types may be mixed in the same polymer.

Specific examples of X ₁ in formula (3) include the structures of formulas (X-1) to (X-46) and the like, which are listed on pages 13 to 14 of International Publication No. 2015/119168. .
The preferred X ₁ structures (A-1) to (A-21) are shown below, but the present invention is not limited thereto.

Of 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 rate of relaxation of accumulated charges. , (A-15) to (A-17) are particularly preferred from the viewpoint of further improving the liquid crystal orientation and the rate of relaxation of accumulated charges.

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

The specific polymer (A) in the present invention contains at least one structural unit selected from the structural unit represented by the above formula (3) and the structural unit imidized from the structural unit of the specific polymer (A). The content is preferably 5 to 100 mol%, more preferably 10 to 100 mol%, and more preferably 20 to 100 mol% from the viewpoint of achieving both liquid crystal orientation and relaxation characteristics of accumulated charge. Is more preferable.
The specific polymer (A) has a structural unit represented by the following formula (4) and / or a structural unit obtained by imidizing the structural unit in addition to the structural unit represented by the formula (3). May be.

In Formula (4), X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and Y ₂ is a divalent organic group derived from a diamine that does not include the structure of Formula (1) in the main chain direction. R ¹¹ has the same definition as R ^{10 in} the formula (3), and R ¹² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Moreover, it is preferable that at least one of two R < ¹² > is a hydrogen atom.

Specific examples of X ₂ include those exemplified for X ₁ in formula (3), including preferred examples. Y ₂ is a divalent organic group derived from a diamine that does not contain the structure of formula (1) in the main chain direction, and the structure is not particularly limited. Y ₂ depends on the degree of required properties such as the solubility of the polymer in the solvent, the coating property of the liquid crystal aligning agent, the orientation of the liquid crystal when it is used as the liquid crystal alignment film, the voltage holding ratio, and the accumulated charge. One type or two or more types may be mixed in the same polymer.

If a specific example of Y ₂ is shown, the structure of Formula (2) published on page 4 of International Publication No. 2015/119168, and Formulas (Y-1) to (P Y-97), structures of (Y-101) to (Y-118); a divalent organic group obtained by removing two amino groups from the formula (2), published on page 6 of International Publication No. 2013/008906 A divalent organic group obtained by removing two amino groups from Formula (1) published on page 8 of International Publication No. 2015/122413; Formula (3) published on page 8 of International Publication No. 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 shown on page 9 of WO 2010-050523 ( A divalent organic group obtained by removing two amino groups from A) to (F) Etc.

Are shown below, but the preferred Y ₂ structure, the present invention is not limited thereto.

Of the Y ₂ structures, (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. 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 charge, 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 the formula (4) are 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, and still more preferably, in terms of weight average molecular weight. 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 the formula (3) and, if necessary, a structural unit represented by the formula (4). In this polyimide, the ring closure rate (also referred to as imidation rate) of the amic acid group is not necessarily 100%, and can be arbitrarily adjusted according to the use and purpose.
Examples of the method for imidizing the polyimide precursor include thermal imidization in which the polyimide precursor solution is heated as it is, or catalytic imidization in which a catalyst is added to the polyimide precursor solution.

<Specific polymer (B)>
The specific polymer (B) contained in the liquid crystal aligning agent of this invention is a polymer which has a structure of following formula (2).

In the formula (2), R ² 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 to 10, preferably 3 to 7. Arbitrary —CH ₂ — may be replaced with an ether, ester, amide, urea, or carbamate bond under conditions that 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. R ⁴ 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 the formula (2) include, but are not limited to, the following.

As a specific polymer (B) in this invention, the polymer obtained using the diamine which has a structure represented by the said Formula (2) is preferable. Specific examples of the polymer include polyamic acid, polyamic acid ester, polyimide, polyurea, polyamide and the like. From the viewpoint of use as a liquid crystal aligning agent, the specific polymer (B) is at least one selected from a polyimide precursor containing a structural unit represented by the following formula (5) and a polyimide which is an imidized product thereof. Preferably it is a seed.

In the formula (5), X ³ is a tetravalent organic group derived from the tetracarboxylic acid derivatives. Specifically, at least one selected from the group consisting of structures represented by the following formulas (X1-1) to (X1-45) is preferable.

In the 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 alignment, R ⁵ , R ⁶ , R ⁷ , and R ⁸ are preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and 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 alignment and reliability, and (X1-10) or (X1-11) ) Is more preferable.

In Formula (5), Y ₃ is a divalent organic group derived from a diamine containing the structure of Formula (2). From the viewpoint of orientation, in Formula (2), R ⁴ 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 a hydrogen atom or a methyl group is particularly preferable from the viewpoint of ease of imidization by heating.

In the specific polymer (B), the specific polymer (B) in the present invention has a ratio of at least one structural unit selected from the structural unit represented by the above formula (5) and the structural unit imidized from the structural unit. It is preferably contained in an amount of 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 preferable.

In addition to the structural unit represented by the above formula (5), the specific polymer (B) in the present invention is further a structural unit represented by the following formula (6) and / or a structural unit obtained by imidizing it. You may have.

However, in Formula (6), R < ¹⁴ > is the same as the definition of R < ¹³ > of said Formula (5). X ₄ 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), Y ₄ is a divalent organic group derived from diamine, and its structure is not particularly limited. Specific examples of Y ₄ include structures of the following formulas (Y-1) to (Y-138).

In the specific polymer (A) and the specific polymer (B), the ratio of the structural unit obtained by imidizing the structural unit of the polyimide precursor (also referred to as imidization ratio) included in each of the specific polymer (A) and the specific polymer (B). It can adjust arbitrarily according to the characteristic of a liquid crystal aligning agent. From the viewpoint of solubility and charge storage characteristics, the imidization ratio in the specific polymer (A) is preferably 0 to 55%, more preferably 0 to 20%. Further, from the viewpoint of liquid crystal alignment, alignment regulating force, and voltage holding ratio, the specific polymer (B) preferably has a higher imidization ratio, preferably 40 to 95%, more preferably 55 to 90%. It is.

<Method for producing polyamic acid ester>
The polyamic acid ester which is a polyimide precursor used in the present invention can be synthesized by the method (1), (2) or (3) shown below.
(1) When synthesizing from polyamic acid The polyamic acid ester can be synthesized by esterifying a polyamic acid obtained from tetracarboxylic dianhydride and diamine.
Specifically, the polyamic acid and the 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.
The esterifying agent is preferably one that can be easily removed by purification, and N, N-dimethylformamide dimethyl acetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, 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 addition amount of the esterifying agent is preferably 2 to 6 molar equivalents per 1 mol of the polyamic acid repeating unit.
The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone in view of polymer solubility. These may be used alone or in combination of two or more. Good. The concentration at the time of synthesis is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation is unlikely to occur and a high molecular weight product is easily obtained.

(2) When synthesized by reaction of tetracarboxylic acid diester dichloride and diamine Polyamic acid ester can be synthesized from tetracarboxylic acid diester dichloride and diamine.
Specifically, tetracarboxylic acid diester dichloride and diamine 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.
As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferable because the reaction proceeds gently. The addition amount of the base 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 view of the solubility of the monomer and polymer, and these may be used alone or in combination. The polymer concentration at the time of synthesis is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint that polymer precipitation is difficult to occur and a high molecular weight product is easily obtained. In order to prevent hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the synthesis of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent mixing of outside air in a nitrogen atmosphere.

(3) When synthesizing from tetracarboxylic acid diester and diamine Polyamic acid ester can be synthesized by polycondensation of tetracarboxylic acid diester and diamine.
Specifically, tetracarboxylic acid diester and diamine 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 It can synthesize | combine by making it react for time.
Examples of the condensing agent include triphenyl phosphite, 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, (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate diphenyl, and the like. The addition amount of the condensing agent is preferably 2 to 3 times the molar amount of the tetracarboxylic acid diester.
As the base, tertiary amines such as pyridine and triethylamine can be used. The addition amount of the base is preferably 2 to 4 times mol with respect to the diamine component from the viewpoint of easy removal and high molecular weight.
In the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably 0 to 1.0 times mol with respect to the diamine component.

Among the methods for synthesizing the three polyamic acid esters, since a high molecular weight polyamic acid ester is obtained, the synthesis method (1) or (2) is particularly preferable.
The polyamic acid ester solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained at room temperature or by heating and drying. Although a poor solvent is not specifically limited, Water, methanol, ethanol, hexane, butyl cellosolve, acetone, toluene etc. are mentioned.

<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 reaction of tetracarboxylic dianhydride and diamine, tetracarboxylic dianhydride in an organic solvent. A method in which a product and a diamine are mixed and reacted is preferred.

The organic solvent used in the above reaction is not particularly limited as long as the produced polyamic acid can be dissolved, but specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, Examples thereof include N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, and γ-butyrolactone. These may be used alone or in combination. Furthermore, even if the solvent does not dissolve the polyamic acid, it may be used by mixing with the above solvent as long as the produced polyamic acid does not precipitate. In addition, since water in the organic solvent inhibits the polymerization reaction and further causes hydrolysis of the generated polyamic acid, it is preferable to use a dehydrated and dried organic solvent as much as possible.

As a method of mixing a tetracarboxylic dianhydride component and a diamine component in an organic solvent, a solution in which the diamine component is dispersed or dissolved in an organic solvent is stirred, and the tetracarboxylic dianhydride component is left as it is or organically. A method of adding by dispersing or dissolving in a solvent, 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 tetracarboxylic dianhydride component and a diamine component. The method of adding alternately etc. are mentioned, In this invention, any of these methods may be sufficient. Moreover, when a tetracarboxylic dianhydride component or a diamine component consists of multiple types of compounds, these multiple types of components may be reacted in advance or may be reacted individually and 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. When the temperature is higher, the polymerization reaction is completed earlier, but when it is too high, a high molecular weight polymer may not be obtained. The reaction can be carried out at any concentration, but if the concentration is too low, it is difficult to obtain a high molecular weight polymer, and if the concentration is too high, the viscosity of the reaction solution becomes too high and uniform stirring is difficult. Therefore, the content is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The initial reaction may be carried out at a high concentration, and then an organic solvent may be added.

The ratio of the tetracarboxylic dianhydride component and the diamine component used for the polyamic acid polymerization reaction is preferably 1: 0.8 to 1.2 in terms of molar ratio. In addition, since the polyamic acid obtained by using an excess of the diamine component may increase the coloration of the solution, it may be 1: 0.8 to 1 if the coloration of the solution is a concern. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1: 1, the higher the molecular weight of the polyamic acid obtained. If the molecular weight of the polyamic acid is too small, the strength of the coating film obtained therefrom may be insufficient. Conversely, if the molecular weight of the polyamic acid is too large, the viscosity of the liquid crystal aligning agent produced therefrom is high. It may become too much, and workability | operativity at the time of coating-film formation and the uniformity of a coating film may worsen. Accordingly, the polyamic acid used in the liquid crystal aligning agent of the present invention has a reduced viscosity (concentration of 0.5 dl / g, 30 ° C. in NMP) of preferably 0.1 to 2.0, more preferably 0.2 to 1.5. .

When it is not desired to include the solvent used for the polymerization of the polyamic acid in the liquid crystal aligning agent of the present invention, or when unreacted monomer components and impurities are present in the reaction solution, the precipitate is collected and purified. In this method, the polyamic acid solution is preferably added to a stirring poor solvent, and the precipitate is recovered. Although it does not specifically limit as a poor solvent used for precipitation collection | recovery of polyamic acid, Methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene etc. can be illustrated. The polyamic acid precipitated by introducing it into a poor solvent can be recovered by filtration, washing and drying at room temperature or under reduced pressure at normal temperature or under reduced pressure. By further dissolving the powder in a good solvent and reprecipitating it 2 to 10 times, the polyamic acid can be purified. When the impurities cannot be removed by a single precipitation recovery operation, it is preferable to perform this purification step. In this case, it is preferable to use three or more kinds of poor solvents such as alcohols, ketones, and hydrocarbons as the poor solvent because the purification efficiency is further increased.

<Production method of polyimide>
The polyimide in the specific polymer (A) and the specific polymer (B) can be produced by imidizing the polyamic acid ester or polyamic acid which is a polyimide precursor.
When a polyimide is produced from a polyamic acid ester, chemical imidization in which a basic catalyst is added to a polyamic acid solution obtained by dissolving the polyamic acid ester solution or the polyamic acid ester resin powder in an organic solvent is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer does not easily decrease during the imidization process.

When a polyimide is produced from a polyamic acid, chemical imidization in which a catalyst is added to the polyamic acid solution obtained by the reaction of a diamine component and tetracarboxylic dianhydride is simple. Chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is unlikely to decrease during the imidization process.

Chemical imidation can be performed by stirring a polymer to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As an organic solvent, the solvent used at the time of the polymerization reaction mentioned above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has an appropriate basicity for proceeding with the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like. Among them, use of acetic anhydride is preferable because purification after completion of the reaction is facilitated.

The temperature for carrying out the imidization reaction is −20 ° C. to 140 ° C., preferably 0 ° C. to 100 ° C., and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times the amic acid group, and the amount of the acid anhydride is 1 to 50 mol times, preferably 3 to 30 mol times the amic acid group. Is double. The imidation ratio of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.
In the solution after the imidation reaction of polyamic acid ester or polyamic acid, the added catalyst and the like remain, so the obtained imidized polymer is recovered by the means described below, and redissolved in an organic solvent. Thus, the liquid crystal aligning agent of the present invention is preferable.

The polyimide solution obtained as described above can be polymerized by pouring into a poor solvent while stirring well. Precipitation is performed several times, and after washing with a poor solvent, a purified polyamic acid ester powder can be obtained at room temperature or by heating and drying.
The poor solvent is not particularly limited, and examples thereof 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 this invention contains the said specific polymer (A) and the said 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.
In addition to the specific polymers (A) and (B), other polymers, that is, a divalent group represented by the formula (1) and a divalent group represented by the formula (2) You may contain the polymer which does not have. Such other polymers include polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or derivatives thereof, poly (styrene-phenylmaleimide) derivative, poly (meth) An acrylate etc. 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, One example 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 solution, and is preferably a coating solution containing a polymer component and an organic solvent for dissolving the polymer component. In that case, content (concentration) of the polymer in a liquid crystal aligning agent can be suitably changed with the setting of the thickness of the coating film to form. 1% by mass or more is preferable from the viewpoint of forming a uniform and defect-free coating film, and 10% by mass or less is preferable from the viewpoint of storage stability of the solution. A particularly preferable 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 the polymer component is uniformly dissolved. Specific examples are N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl. -2-Imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone and the like can be mentioned. Of these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone is preferably used.

Moreover, the organic solvent contained in the liquid crystal aligning agent may be a mixed solvent that is used in combination with 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-mentioned solvent. Such a mixed solvent is preferably used also in the liquid crystal aligning agent of the present invention. Specific examples of the organic solvent to be used in combination are given below, but the organic solvent is not limited to these examples.

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 Tyl 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-ethoxybutyl Acetate, 1-methylpentyl acetate, 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, Lopylene 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, di 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, Ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methylethyl 3-ethoxypropionate, 3-methoxypropionic acid Ethyl, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, milk Ethyl ester, lactic acid n- propyl ester, lactate n- butyl ester, lactic acid isoamyl ester, the following formula [D-1] and the like solvents represented by ~ [D-3].

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

Among these, preferred solvent combinations include N-methyl-2-pyrrolidone, γ-butyrolactone, ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, N-ethyl-2- Pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol mono Butyl ether, 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, diisopropyl ether, N-methyl-2-pi Examples thereof include loridone, γ-butyrolactone, 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 application device, application conditions, application environment, and the like of the liquid crystal aligning agent.

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

Examples of the compound that improves the adhesion between the liquid crystal alignment film and the substrate include a functional silane-containing compound and an epoxy group-containing compound, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- 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-aminopropyltrimethoxy Sisilane, 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-amino Propyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3 Aminopropyltrimethoxysilane, -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 di Glycidyl 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 ′,-tetraglyci Etc. Le-4,4'-diaminodiphenylmethane and the like.

In addition, 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 mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. If the amount is less than 0.1 parts by mass, the effect cannot be expected. 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. If an example of the method of obtaining a liquid crystal aligning film from a liquid crystal aligning agent is given, a liquid crystal aligning agent in the form of a coating solution is applied to a substrate, dried and baked on a film obtained by rubbing or photo-aligning. And a method of performing an alignment treatment.

The substrate on which the liquid crystal aligning agent is applied is not particularly limited as long as it is a highly transparent substrate, and a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used together with a glass substrate or a silicon nitride substrate. At that time, it is preferable to use a substrate on which an ITO electrode or the like for driving the liquid crystal is used from the viewpoint of simplification of the process. Further, in the reflection type liquid crystal display element, an opaque material such as a silicon wafer can be used as long as only one substrate is used, and a material that reflects light such as aluminum can be used for the electrode in this case.

The method for applying the liquid crystal aligning agent is not particularly limited, but industrially, screen printing, offset printing, flexographic printing, inkjet 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 on the substrate, the solvent is evaporated and baked by a heating means such as a hot plate, a thermal circulation oven, an IR (infrared) oven, or the like. Arbitrary temperature and time can be selected for the drying and baking steps after applying the liquid crystal aligning agent. Usually, in order to sufficiently remove the contained solvent, there is a condition of baking at 50 to 120 ° C. for 1 to 10 minutes and then baking at 150 to 300 ° C. for 5 to 120 minutes.

The thickness of the liquid crystal alignment film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may be lowered, so that it is preferably 5 to 300 nm, more preferably 10 to 200 nm.
The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film of a horizontal electric field type liquid crystal display element such as an IPS mode or an FFS mode, and is particularly useful as a liquid crystal alignment film of an FFS mode liquid crystal display element.

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

Specifically, a transparent glass substrate is 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 electrode and the segment electrode. The insulating film can be, for example, a film made of SiO ₂ —TiO ₂ formed by a sol-gel method. Next, a liquid crystal alignment film is formed on each substrate under the above conditions.

Next, for example, an ultraviolet curable sealing material is disposed at a predetermined position on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystals are disposed at predetermined positions on the liquid crystal alignment film surface. After that, the other substrate is bonded and pressure-bonded so that the liquid crystal alignment film faces, and the liquid crystal is spread on the front surface of the liquid crystal alignment film, and then the entire surface of the substrate is irradiated with ultraviolet rays to cure the sealing material. Get a cell.
Alternatively, as a step after forming the liquid crystal alignment film on the substrate, an opening that can be filled with liquid crystal from the outside is provided when the sealing material is disposed at a predetermined location on one substrate, and the liquid crystal is After the substrates are bonded without being arranged, 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 liquid crystal material may be injected by a vacuum injection method or a method utilizing capillary action in the atmosphere.

In any of the above methods, in order to secure a space filled with a liquid crystal material in the liquid crystal cell, columnar protrusions are provided on one substrate, spacers are scattered on one substrate, or a sealing material It is preferable to take a means such as mixing a spacer with or combining them.

Examples of the liquid crystal material include a nematic liquid crystal and a smectic liquid crystal. Among them, a nematic liquid crystal is preferable, and either a positive liquid crystal material or a negative liquid crystal material 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.
The liquid crystal display element of the present invention is not limited to the above description as long as the liquid crystal aligning agent of the present invention is used, and may be produced by other known methods. The process of obtaining a liquid crystal display element is disclosed in, for example, paragraph 0074 on page 17 to paragraph 0081 on page 19 of Japanese Unexamined Patent Publication No. 2015-135393.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to these examples. In addition, the symbol of a compound and a solvent is 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.) at a sample amount of 1.1 mL, cone rotor TE-1 (1 ° 34 ′, R24), and a temperature of 25 ° C. .

<Measurement of imidization ratio>
The imidation ratio of polyimide was measured as follows. 30 mg of polyimide powder was added to an NMR (nuclear magnetic resonance) sample tube (NMR sampling tube standard,
(5) (manufactured by Kusano Kagaku Co., Ltd.))
05 mass% TMS (tetramethylsilane) mixture) (0.53 ml) was added and completely dissolved by applying ultrasonic waves. This solution was measured for proton NMR at 500 MHz with an NMR measuring instrument (JNW-ECA500) (manufactured by JEOL Datum). The imidation rate is determined based on protons derived from structures that do not change before and after imidation as reference protons, and the peak integrated value of these protons and proton peaks derived from NH groups of amic acid that appear in the vicinity of 9.5 ppm to 10.0 ppm. It calculated | required by the following formula | equation using the integrated value.
Imidization rate (%) = (1−α · x / y) × 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 (imidation rate is 0%).
It is the number ratio of the reference proton to one H group proton.

(Synthesis Example 1)
In a 1 L four-necked flask equipped with a stirrer and a nitrogen inlet tube, 54.7 g (224 mmol) of DA-1 and 53.4 g (95.9 mmol) of DA-2 were weighed, 613 g of NMP was added, and nitrogen was added. While feeding, the mixture was dissolved by stirring. While stirring this diamine solution under water cooling, 89.5 g (298 mmol) of CA-1 was added, 175 g of NMP was further added, and the mixture was stirred at 23 ° C. for 12 hours in a nitrogen atmosphere to obtain a polyamic acid (viscosity: 890 mPa · s). Solution was obtained.
To a 3 L Erlenmeyer flask containing a stirrer, 900 g of this polyamic acid solution was taken, 1350 g of NMP, 74.3 g of acetic anhydride and 34.6 g of pyridine were added, and the mixture was stirred at room temperature for 30 minutes. The reaction was performed for 2 hours. This reaction solution was put into 8300 g of methanol, and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a polyimide powder (imidization ratio: 66%).

In a 500 mL Erlenmeyer flask containing a stir bar, 50.7 g of this polyimide powder was taken, 372 g of NMP was added, and the mixture was dissolved by stirring at 50 ° C. for 20 hours. Further, 11.9 g of this solution was taken into a 200 mL Erlenmeyer flask containing a stirring bar, and 4.49 g of NMP, 5.86 g of GBL, and 1% by mass of 3-glycidoxypropyltriethoxysilane were contained. 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)
In a 1 L four-necked flask equipped with a stirrer and a nitrogen introduction tube, DA-1 (86.0 g, 352 mmol), DA-2 (53.4 g, 95.9 mmol), and DA-3 (76.5 g, 191 mmol) were added. ) Weighed out, added 1580 g of NMP, and stirred to dissolve while feeding nitrogen. While stirring this diamine solution under water cooling, 93.2 g (416 mmol) of CA-2 was added, 168 g of NMP was further added, and the mixture was stirred at 40 ° C. for 3 hours under a nitrogen atmosphere. Further, 28.2 g (143 mmol) of CA-3 was added, 160 g of NMP was further 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).
Into a 3 L Erlenmeyer flask containing a stir bar, 800 g of this polyamic acid solution was collected, 700 g of NMP, 69.7 g of acetic anhydride, and 18.0 g of pyridine were added, and the mixture was stirred at room temperature for 30 minutes, and then 55 ° C. For 3 hours. This reaction solution was put into 5600 g of methanol, and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a polyimide powder (imidization rate: 75%).

In a 300 mL Erlenmeyer flask containing a stirring bar, 20.3 g of this polyimide powder was taken, 148 g of NMP was added, and the mixture was stirred and dissolved at 50 ° C. for 20 hours. Further, 6.31 g of this solution was taken into a 200 mL Erlenmeyer flask containing a stirring bar, and an NMP solution containing 2.06 g of NMP, 3.00 g of GBL, and 1% by mass of 3-glycidoxypropyltriethoxysilane was obtained. 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)
In a 1 L four-necked flask equipped with a stirrer and a nitrogen introduction tube, weighed 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. 1380 g of NMP was added and dissolved by stirring while feeding nitrogen. While stirring this diamine solution under water cooling, 93.2 g (416 mmol) of CA-2 was added, and 214 g of NMP was further added, followed by stirring at 40 ° C. for 3 hours under a nitrogen atmosphere. Further, 32.6 g (166 mmol) of CA-3 was added, and 185 g of NMP was further added, followed by stirring at 23 ° C. for 4 hours in a nitrogen atmosphere to obtain a polyamic acid solution (viscosity: 200 mPa · s).

Into a 3 L Erlenmeyer flask containing a stir bar, 700 g of this polyamic acid solution was taken, 612 g of NMP, 60.4 g of acetic anhydride, and 15.6 g of pyridine were added, and the mixture was stirred at room temperature for 30 minutes. For 3 hours. This reaction solution was put into 4900 g of methanol, and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a polyimide powder (imidization rate: 75%).
In a 200 mL Erlenmeyer flask containing a stir bar, 18.1 g of this polyimide powder was taken, 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.CS of BCS. 73 g was added and stirred for 2 hours with a magnetic stirrer to obtain a polyimide solution (SPI-3).

(Synthesis Example 4)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 6.31 g (16.0 mmol) of DA-5 was weighed, 47.6 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution under water cooling, 1.69 g (8.61 mmol) of CA-3 was added, and 10.2 g of NMP was further added, followed by stirring at 23 ° C. for 3 hours under a nitrogen atmosphere. Further, 1.39 g (6.37 mmol) of CA-4 was added, and 10.2 g of NMP was further added, followed by stirring at 50 ° C. for 12 hours under a nitrogen atmosphere to obtain a polyamic acid solution (viscosity: 250 mPa · s). .
In a 100 mL Erlenmeyer flask containing a stir bar, 14.4 g of this polyamic acid solution was taken, NMP 8.39 g, GBL 8.08 g, and NMP containing 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)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 4.41 g (40.7 mmol) of DA-6 and 1.79 g (7.20 mmol) of DA-7 were weighed, and 55.8 g of NMP was added. The solution was stirred and dissolved while feeding 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 mixture was stirred at 23 ° C. for 12 hours under a nitrogen atmosphere to obtain a polyamic acid solution ( Viscosity: 815 mPa · s) was obtained.
In a 200 mL Erlenmeyer flask containing a stir bar, 30 g of this polyamic acid solution was collected, 45 g of NMP, 3.64 g of acetic anhydride, and 1.69 g of pyridine were added, and the mixture was stirred at room temperature for 30 minutes, and then at 40 ° C. The reaction was performed for 3 hours. This reaction solution was put into 300 g of methanol, and the resulting precipitate was separated by filtration. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 60 ° C. to obtain a polyimide powder (imidization ratio: 73%).

In a 100 mL Erlenmeyer flask containing a stir bar, 4.10 g of this polyimide powder was collected, 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 dispensed into a 100 mL Erlenmeyer flask containing a stirring bar, 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)
In a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube, 7.93 g (20.0 mmol) of DA-8 was weighed, 87.0 g of NMP was added, and the mixture was stirred and dissolved while feeding 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. Further, 1.74 g (8.00 mmol) of CA-4 was added, and 10.1 g of NMP was further added, followed by stirring at 50 ° C. for 12 hours under a nitrogen atmosphere to obtain a polyamic acid solution (viscosity: 140 mPa · s). .
In a 100 mL Erlenmeyer flask containing a stir bar, 6.91 g of this polyamic acid solution was taken, NMP 1.35 g, GBL 2.98 g, and NMP containing 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)
In a 50 mL Erlenmeyer flask containing a stir bar, 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. The mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-1).

(Example 2)
In a 50 mL Erlenmeyer flask containing a stir bar, 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. Then, the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-2).

(Example 3)
In a 50 mL Erlenmeyer flask containing a stir bar, 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. Then, the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-3).

Example 4
In a 50 mL Erlenmeyer flask containing a stir bar, 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. Then, the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (A-4).

(Comparative Example 1)
In a 50 mL Erlenmeyer flask containing a stir bar, 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. Then, the mixture was stirred with a magnetic stirrer for 2 hours to obtain a liquid crystal aligning agent (B-1).

(Comparative Example 2)
In a 50 mL Erlenmeyer flask containing a stir bar, weigh out 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. The mixture was 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 the liquid crystal aligning agent (B-3).

A method for manufacturing a liquid crystal cell for evaluating the stored charge relaxation characteristics, flicker characteristics, and liquid crystal alignment is described below.
A liquid crystal cell having a configuration of an FFS liquid crystal display element is manufactured. First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 35 mm and a thickness of 0.7 mm. On the substrate, an IZO electrode constituting the counter electrode as the first layer is formed on the entire surface. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film. A comb-like pixel electrode formed by patterning an IZO film is arranged as a third layer on the second layer SiN film 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 first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

The third-layer pixel electrode has a comb-like shape configured by arranging a plurality of U-shaped electrode elements having a bent central portion. The width in the short direction of each electrode element is 3 μm, and the distance between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is configured by arranging a plurality of bent-shaped electrode elements having a bent central portion, the shape of each pixel is not a rectangular shape, and the central portion is similar to the electrode element. It has a shape that is bent in the shape of bold, similar to the “Kugi”. Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.
When the first region and the second region of each pixel are compared, 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 to 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 rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode in the substrate plane is It is comprised so that it may become a mutually reverse direction.

Next, the liquid crystal aligning agents obtained in Examples and Comparative Examples were filtered through a filter having a pore diameter of 1.0 μm, and then applied to the prepared substrate with electrodes by spin coating. After drying on an 80 ° C. hot plate for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C. for 20 minutes to obtain a polyimide film having a 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: inclined by 10 ° with respect to the third layer IZO comb-teeth electrode Then, ultrasonic cleaning was performed for 1 minute in pure water for cleaning, and water droplets were removed by air blow. Then, it dried for 15 minutes at 80 degreeC, and obtained the board | substrate with a liquid crystal aligning film. Also, as a counter substrate, a polyimide film is formed on a glass substrate having an ITO electrode on the back surface and having a columnar spacer with a height of 4 μm in the same manner as described above. A substrate with a liquid crystal alignment film was obtained. One set of these two substrates with a liquid crystal alignment film is printed, and the sealant is printed on the substrate leaving the liquid crystal injection port. The other substrate has the liquid crystal alignment film surface facing and the rubbing direction is antiparallel. They were pasted together. Thereafter, the sealing agent was cured to produce an empty cell having a cell gap of 4 μm. Liquid crystal MLC-3019 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 120 ° C. for 1 hour and allowed to stand at 23 ° C. overnight, and then used for evaluation of liquid crystal alignment.

<Relaxation characteristics of accumulated charge>
The liquid crystal cell is placed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, and the pixel electrode and the counter electrode are short-circuited to be at the same potential, and the LED is displayed from under the two polarizing plates. The angle of the liquid crystal cell was adjusted so that the brightness of the LED backlight transmitted light measured on the two polarizing plates was minimized by irradiating the backlight.
Next, while applying a rectangular wave with a frequency of 30 Hz to this liquid crystal cell, the VT characteristics (voltage-transmittance characteristics) at a temperature of 23 ° C. are measured, and an AC voltage with a relative transmittance of 23% is measured. Calculated. Since this AC voltage corresponds to a region where the change in luminance with respect to the voltage is large, it is convenient to evaluate the accumulated charge via the luminance.

Next, a rectangular wave having a relative transmittance of 23% at a temperature of 23 ° C. and a frequency of 30 Hz was applied for 5 minutes, and then a +1.0 V DC voltage was superimposed and driven for 30 minutes. Thereafter, the DC voltage was turned off, and only a rectangular wave having an AC voltage with a relative transmittance of 23% and a frequency of 30 Hz was applied for 30 minutes.
The faster the accumulated charge is relaxed, the faster the charge accumulation in the liquid crystal cell when the DC voltage is superimposed. Therefore, the accumulated charge relaxation characteristic is a state where the relative transmittance immediately after the DC voltage is superimposed is 30% or more. It was evaluated based on the time required to decrease to 23%. That is, when the relative transmittance was reduced to 23% within 30 minutes, it was defined as “good”, and when the relative transmittance did not decrease to 23% even after 30 minutes, it was defined as “bad”.

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

Next, the LED backlight that had been turned on at a temperature of 23 ° C. was temporarily turned off and left to block light for 72 hours. Then, the LED backlight was turned on again, and the relative transmittance was 23% simultaneously with the start of lighting of the backlight. An alternating voltage with a frequency of 30 Hz was applied and the liquid crystal cell was driven for 30 minutes to track the flicker amplitude. The flicker amplitude is a data acquisition / data logger switch unit 34970A (Agilent Technologies) that connects the transmitted light of the LED backlight that has passed through the two polarizing plates and the liquid crystal cell between them through a photodiode and an IV conversion amplifier. ). The flicker level was calculated by the following formula.
Flicker level (%) = {flicker amplitude / (2 × z)} × 100
In the above formula, z is a value obtained by reading the luminance when driven by an AC voltage having a frequency of 30 Hz with a relative transmittance of 23% by the data collection / data logger switch unit 34970A.
The flicker characteristics are evaluated as “good” when the flicker level is kept below 3% by 30 minutes after the start of lighting of the LED backlight and the application of the AC voltage, and the flicker level after 30 minutes. Was defined as “bad” and evaluated.

<Evaluation of liquid crystal alignment>
Using this liquid crystal cell, an alternating voltage of 9 VPP was applied for 190 hours at a frequency of 30 Hz in a constant temperature environment of 60 ° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left as it was at room temperature for one day.
After leaving, the liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal, and the backlight is turned on with no voltage applied so that the brightness of the transmitted light is 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 became darkest to the angle at which the first region became darkest was calculated as an angle Δ. Similarly, for the second pixel, the second area was compared with the first area, and a similar angle Δ was calculated. 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 value of the angle Δ of this liquid crystal cell was less than 0.4 degrees, it was defined as “good”, and when the value of the angle Δ was 0.4 degrees or more, it was defined as “bad”.

(Example 5)
The liquid crystal aligning agent (A-1) obtained in Example 1 was filtered through a filter having a pore size of 1.0 μm, and then a liquid crystal cell was produced as described above. As a result of evaluating the relaxation characteristics of the stored charge for this liquid crystal cell, the time required for the relative transmittance to drop to 23% was 8 minutes, which was favorable.
Next, as a result of evaluating the flicker characteristics of this liquid crystal cell, the flicker level was 1%, which was favorable. Moreover, as a result of evaluating the liquid crystal orientation of this liquid crystal cell, Δ was 0.21 ° and good.

(Example 6)
Except that the liquid crystal aligning agent (A-2) obtained in Example 2 was used, the relaxation characteristics of the accumulated charges were evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was 4 minutes and was good.
Next, as a result of evaluating the flicker characteristics by the same method as in Example 5, the flicker level was 1%, which was favorable. Moreover, as a result of evaluating liquid crystal orientation by the method similar to Example 5, (DELTA) was 0.06 degree and was favorable.

(Example 7)
Except that the liquid crystal aligning agent (A-3) obtained in Example 3 was used, as a result of evaluating the relaxation characteristics of accumulated charges by the same method as in Example 5, it was found that the relative transmittance decreased to 23%. The time required was 4 minutes and was good.
Next, as a result of evaluating the flicker characteristics by the same method as in Example 5, the flicker level was 1%, which was favorable. Moreover, as a result of evaluating liquid crystal orientation by the method similar to Example 5, (DELTA) was 0.05 degree and was favorable.

(Example 8)
Except that the liquid crystal aligning agent (A-4) obtained in Example 4 was used, as a result of evaluating the relaxation characteristics of accumulated charges by the same method as in Example 5, it was found that the relative transmittance decreased to 23%. The time required was good, 26 minutes.
Next, as a result of evaluating flicker characteristics by the same method as in Example 5, the flicker level was 0.3%, which was favorable. Moreover, as a result of evaluating liquid crystal orientation by the method similar to Example 5, (DELTA) was 0.22 degree | times and favorable.

(Comparative Example 4)
Except that the liquid crystal aligning agent (B-1) obtained in Comparative Example 1 was used, the relaxation characteristics of the accumulated charges were evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was good, 26 minutes.
Next, as a result of evaluating the flicker characteristics by the same method as in Example 5, the flicker level was 2%, which was favorable. Moreover, as a result of evaluating liquid crystal orientation by the method similar to Example 5, (DELTA) was 0.63 degree | times and was unsatisfactory.

(Comparative Example 5)
Except that the liquid crystal aligning agent (B-2) obtained in Comparative Example 2 was used, the relaxation characteristics of the accumulated charges were evaluated in the same manner as in Example 5. As a result, the relative transmittance decreased to 23%. The time required was good, 24 minutes.
Next, as a result of evaluating the flicker characteristics by the same method as in Example 5, the flicker level was 6%, which was poor. Moreover, as a result of evaluating liquid crystal orientation by the method similar to Example 5, (DELTA) was 0.16 degree and was favorable.

(Comparative Example 6)
Except that the liquid crystal aligning agent (B-3) obtained in Comparative Example 3 was used, the relaxation characteristics of the accumulated charges were evaluated in the same manner as in Example 5. As a result, the relative transmittance was 23 even after 30 minutes. % Did not fall and was bad.
Next, as a result of evaluating the flicker characteristics in the same manner as in Example 5, the flicker level was 0.7%, which was favorable. Moreover, as a result of evaluating liquid crystal orientation by the method similar to Example 5, (DELTA) was 0.11 degree and was favorable.

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

The liquid crystal aligning agent of the present invention is widely used for a liquid crystal display element of a vertical electric field method such as a TN method or a VA method, particularly a horizontal electric field method such as an IPS method or an FFS method.
It should be noted that the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2016-158014 filed on August 10, 2016 are cited herein as disclosure of the specification of the present invention. Incorporate.

Claims (13)

1. The liquid crystal aligning agent characterized by including the polymer (A) which has a structure represented by following formula (1), and the polymer (B) which has a structure of following formula (2).
   

   

   

   In the formula (1), R ¹ represents hydrogen or an alkyl group having 1 to 3 carbon atoms. In the formula (2), R ² represents a single bond or a divalent organic group, and R ³ represents — (CH ₂ ) a structure represented by _n − (where n is an integer of 2 to 20, and arbitrary —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, Any hydrogen atom may be replaced with a monovalent organic group.
2. The polymer (A) is a polyimide precursor (A) which is a polycondensate 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. The liquid crystal aligning agent according to claim 1, which is at least one polymer selected from the group consisting of:
3. The polymer (B) is a polyimide precursor (B) which is a polycondensate of a diamine having a structure represented by the formula (2) and a tetracarboxylic dianhydride, and a polyimide (B) The liquid crystal aligning agent according to claim 1, which is at least one polymer selected from the group consisting of:
4. The liquid crystal aligning agent according to any one of claims 1 to 3, 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 1 ¹⁰ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
5. In the formula (3), the liquid crystal aligning agent of claim 4, Y ₁ is represented by any of the following equation.
   

   

   
6. The liquid crystal aligning agent according to claim 4 or 5, 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.
7. The liquid crystal aligning agent according to any one of claims 1 to 6, 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 3 ¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
8. The content of the polymer (A) is 10 to 95% by mass with respect to the total amount of the polymer (A) and the polymer (B), and the content of the polymer (B) is The liquid crystal aligning agent according to any one of claims 1 to 7, which is 5 to 90% by mass.
9. The liquid crystal aligning agent according to any one of claims 1 to 8, comprising an organic solvent that dissolves the polymer (A) and the polymer (B).
10. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 9.
11. A liquid crystal display element comprising the liquid crystal alignment film according to claim 10.
12. The liquid crystal display element according to claim 11, wherein the liquid crystal display element is of a horizontal electric field drive system.
13. The liquid crystal display element according to claim 11 or 12, wherein the liquid crystal display element is an FFS system.