TWI762464B - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal display element using the same, and polymer - Google Patents

Abstract

Provided are a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element that can obtain a liquid crystal alignment film that is excellent in voltage retention, has a fast relaxation of accumulated charges, and is less likely to cause flicker during driving.

A liquid crystal aligning agent containing a polymer obtained from a diamine having a structure represented by formula (1) and an organic solvent.

(R₁為氫、氟原子、氰基、羥基或一價有機基，*為鍵結於其他基的部位。苯環的任意氫原子可被一價有機基取代。)

(R ₁ is hydrogen, a fluorine atom, a cyano group, a hydroxyl group or a monovalent organic group, and * is a site for bonding to other groups. Any hydrogen atom of the benzene ring may be substituted by a monovalent organic group.)

Description

Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal display element using the same, and polymer

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

Liquid crystal display elements are widely used in display parts of computers, mobile phones, smart phones, and televisions. 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 for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of liquid crystal molecules in the liquid crystal layer, and a switching supply to the pixel electrode. Thin film transistors (TFTs) for electrical signals, etc. As a driving method of liquid crystal molecules, a vertical electric field method such as a TN method and a VA method, and a lateral electric field method such as an IPS method and an FFS method are known. The transverse electric field method in which electrodes are formed only on one side of the substrate and a voltage is applied in the direction parallel to the substrate is known to have a wide range of applications compared with the conventional vertical electric field method in which a voltage is applied to electrodes formed on the upper and lower substrates to drive liquid crystals. A liquid crystal display element capable of high-quality display with viewing angle characteristics.

Although the liquid crystal cell of the lateral electric field type has excellent viewing angle characteristics, there are few electrode portions formed in the substrate, so that the voltage holding ratio is low, and the display contrast is reduced without sufficient voltage applied to the liquid crystal. Also, liquid crystal alignment When the stability is small, the liquid crystal cannot return to the initial state when the liquid crystal is driven for a long time, which causes a decrease in contrast or image sticking. Therefore, the stability of the liquid crystal alignment is important. In addition, static electricity is easily accumulated in the liquid crystal cell. Even if positive and negative asymmetrical voltages generated by driving are applied, charges will be accumulated in the liquid crystal cell. These accumulated charges will cause the disorder of the liquid crystal alignment or affect the display in the form of afterimages. Influence, thereby significantly reducing the display quality of the liquid crystal element. In addition, even if the liquid crystal cell is irradiated with backlight light immediately after driving, electric charges are accumulated, afterimages are generated even in short-time driving, and problems such as changes in the size of flicker occur during driving.

Patent Document 1 discloses a liquid crystal aligning agent containing a specific diamine and an aliphatic tetracarboxylic acid derivative as a liquid crystal aligning agent that is excellent in voltage retention and reduces charge accumulation when used in a liquid crystal display element of such a lateral electric field system. However, along with the higher performance of liquid crystal display elements, the properties required for liquid crystal alignment films are becoming more and more severe, and it is difficult to fully satisfy all the required properties in such conventional technologies.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] International Publication No. WO2004/021076

An object of the present invention is to provide a device that can obtain excellent voltage retention, rapid relaxation of accumulated charges, and less flicker during driving. Liquid crystal alignment agent for liquid crystal alignment film, liquid crystal alignment film, and liquid crystal display element.

As a result of diligently examining in order to solve the above-mentioned problems, the present inventors found that by introducing a specific structure into a polymer contained in a liquid crystal aligning agent, various properties were simultaneously improved, and the present invention was completed. The present invention is made based on this knowledge, and the main points are as follows.

1. A liquid crystal aligning agent characterized by containing a polymer obtained by containing a diamine having a structure represented by the following formula (1) and an organic solvent.

(R₁為氫、氟原子、氰基、羥基、或一價有機基，*為鍵結於其他基的部位。苯環的任意氫原子可被一價有機基取代。)

(R ₁ is hydrogen, a fluorine atom, a cyano group, a hydroxyl group, or a monovalent organic group, and * is a site for bonding to other groups. Any hydrogen atom of the benzene ring may be substituted by a monovalent organic group.)

2. The polymer is a group consisting of a polyimide precursor of a polycondensate of a diamine and a tetracarboxylic dianhydride having a structure represented by the aforementioned formula (1) and a polyimide of an imide compound thereof The liquid crystal aligning agent according to the aforementioned 1 of at least one polymer selected from the group.

3. The aforementioned diamine is the liquid crystal aligning agent described in the aforementioned 1 or 2 represented by the following formula (2).

(R₁的定義同前述式(1)，R₂各自獨立，為單鍵或下述式(3)之構造，n為1~3的整數。苯環的任意氫原子可被一價有機基取代。)

(The definition of R ₁ is the same as the above formula (1), R ₂ is independent of each other, is a single bond or the structure of the following formula (3), n is an integer of 1 to 3. Any hydrogen atom of the benzene ring can be replaced by a monovalent organic group replace.)

(R₃為單鍵、-O-、-COO-、-OCO-、-(CH₂)_l-、-O(CH₂)_mO-、-CONH-、及-NHCO-所選出的2價有機基(l、m為1~5的整數)、*₁為與式(2)中之苯環鍵結的部位，*₂為與式(2)中之胺基鍵結的部位。)

(R ₃ is a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) ₁ -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO- Organic group (l, m are integers of 1 to 5), * ₁ is a site bonded to the benzene ring in the formula (2), and * ₂ is a site bonded to the amine group in the formula (2).)

4. The aforementioned polyimide precursor is the liquid crystal aligning agent described in the aforementioned 1 to 3 represented by the following formula (6).

(X₁為源自四羧酸衍生物的4價有機基，Y₁為源自含式(1)之構造的二胺的2價有機基，R₄為氫原子或碳數1~5的烷基。) [hua 4]

(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 the formula (1), R ₄ is a hydrogen atom or a carbon number of 1 to 5 alkyl.)

5. In the aforementioned formula (6), the structure of X ₁ is at least one liquid crystal aligning agent according to the aforementioned 4 selected from the group consisting of the structures of the formulas (A-1) to (A-21) described later.

6. The polymer system having the structural unit represented by the aforementioned formula (6) contains 10 mol% or more of the liquid crystal aligning agent described in the aforementioned 4 or 5 relative to the total polymer contained in the liquid crystal aligning agent.

7. The aforementioned organic solvent is the liquid crystal aligning agent according to the aforementioned 4 to 6 containing at least one selected from the group consisting of 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether.

8. A liquid crystal alignment film obtained by using the liquid crystal alignment agent according to any one of the above 1 to 7.

9. The liquid crystal display element provided with the liquid crystal alignment film of the said 8.

10. The liquid crystal display element is the liquid crystal display element according to the above-mentioned 9 of the transverse electric field driving method.

11. A polyimide precursor of a polycondensate of a diamine and a tetracarboxylic dianhydride having a structure represented by the following formula (1) and a polyimide of an imide compound thereof At least one polymer selected from the group.

(R₁及*同前述1。)

(R ₁ and * are the same as the above 1.)

12. The above-mentioned diamine is the polymer described in the above-mentioned 11 represented by the following formula (2).

(R₁、R₂、及n同前述3。)

(R ₁ , R ₂ , and n are the same as in 3 above.)

13. The aforementioned polyimide precursor is the polymer described in the aforementioned 11 or 12 represented by the following formula (6).

(X₁、Y₁及R₄同前述4。)

(X ₁ , Y ₁ and R ₄ are the same as the above 4.)

14. In the aforementioned formula (6), the structure of X ₁ is at least one polymer of the aforementioned 13 selected from the group consisting of the structures of the following formulas (A-1) to (A-21).

By using the liquid crystal aligning agent of the present invention, it is possible to provide a liquid crystal aligning film that is less prone to flicker (Flicker) during driving, and a liquid crystal display element having excellent display characteristics, with fast relaxation of accumulated charges. It is not clear why the present invention can solve the above-mentioned problems, but it is roughly as follows.

The above-mentioned structure (1) of the polymer contained in the liquid crystal aligning agent of the present invention is considered to have a conductive pyrrole structure and a conjugated structure, and thereby, for example, in a liquid crystal alignment film, charge transfer and accumulation can be promoted. Charge Moderator.

[The best form of implementing the invention]

<Amine with a specific structure>

The liquid crystal aligning agent of the present invention contains a polymer (also referred to as a specific polymer in the present invention) obtained from a diamine having a structure of the following formula (1) (also referred to as a specific diamine in the present invention) and an organic solvent.

[hua 8]

In the above formula (1), R ₁ is hydrogen, a fluorine atom, a cyano group, a hydroxyl group, or a monovalent organic group, and * is a site bonded to another group. The hydrogen atom of the benzene ring can be optionally substituted by a monovalent organic group.

Examples of the monovalent organic group include an alkyl group having 1 to 10, preferably 1 to 3 carbon atoms, an alkenyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkenyl group, or a fluoroalkoxy group. Among them, R ₁ is preferably a hydrogen atom or a methyl group.

In the structure of the above formula (1), the bonding position of the pyrrole ring with respect to the benzene ring is generally a carbon atom next to the nitrogen atom on the pyrrole ring as shown in the following formula (1-1) from the viewpoint of charge transfer. better.

The above-mentioned specific diamine can be represented by, for example, the following formula (1-2), especially the diamine represented by the following formula (1-3) is more preferable, and the diamine represented by the formula (1-4) is more preferable .

[Chemical 10]

In formulas (1-2) to (1-4), the definition of R ₁ is the same as that of the aforementioned formula (1), and Q ₁ and Q ₂ are each independently and are a single bond or a divalent organic group, that is, Q ₁ and Q ₂ may be of mutually different configurations. In addition, the two Q ₂ in the formula (1-4) may have mutually different structures. Furthermore, any hydrogen atom of the benzene ring may be substituted with a monovalent organic group as in the case of the above formula (1).

As a preferable example of the said specific diamine, the diamine represented by following formula (2) is mentioned, for example, More preferably, it is a diamine represented by formula (2-1).

The definition of R ₁ in the above formula (2) and formula (2-1) is the same as that in the above formula (1). The two R ₂ are each independently, and are a single bond or the structure of the following formula (3). Also, as in the case of the above formula (1), any hydrogen atom of the benzene ring may be substituted with a monovalent organic group.

In the above formula (3), R ₃ is a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) _l -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO -A divalent organic group selected from the group, where l and m are integers from 1 to 5. Among them, it is preferable that R ₃ is a single bond, -O-, -COO-, -OCO-, -CONH-, or -NHCO-, from the viewpoint of relaxation of the accumulated charge. In addition, * ₁ is a site|part which couple|bonded with the benzene ring in Formula (2), and * ₂ is a site|part which couple|bonded with the amine group in Formula (2).

n in the above formula (2) and formula (2-1) is an integer of 1 to 3. Preferably it is 1 or 2.

Specific examples of the diamine of the above formula (2) include, but are not limited to, the following. Among them, from the viewpoint of the relaxation of accumulated charge, With (2-1-1), (2-1-2), (2-1-3), (2-1-5), (2-1-8), (2-1-9), ( 2-1-10), (2-1-11) or (2-1-12) are preferred, (2-1-1), (2-1-2), (2-1-3), ( 2-1-11) or (2-1-12) are particularly preferred.

<Synthesis method of specific diamine>

The method of synthesizing the above-mentioned specific diamine is not particularly limited. For example, use A method in which the nitro group contained in the dinitro compound represented by the following formula (4) is converted into an amine group by a reduction reaction.

In formula (4), the definition of R ₁ is the same as that of formula (1) above

The catalyst used in the above-mentioned reduction reaction is preferably a commercially available activated carbon-supported metal, and examples thereof include palladium-activated carbon, platinum-activated carbon, rhodium-activated carbon, and the like. In addition, palladium hydroxide, platinum oxide, Reye's nickel, etc. may also be used, and it is not necessarily necessary to use an activated carbon-supported metal catalyst. Palladium-activated carbon, which is generally widely used, is preferred because good results can be obtained.

In order to carry out the reduction reaction more efficiently, the reaction is also carried out under the coexistence of activated carbon. In this case, the amount of activated carbon to be used is not particularly limited, but is preferably 1 to 30 mass %, more preferably 10 to 20 mass %, relative to the dinitro compound (4). For the same reason, there are cases where the reaction is carried out under pressure. In this case, in order to avoid the reduction of the benzene nucleus, it is carried out in a pressure range up to 20 atmospheres. The reaction is preferably carried out in a range up to 10 atmospheres.

The solvent is a solvent that does not react with each raw material, and can be used without limitation. For example, aprotic polar organic solvents (dimethylformamide, dimethylsulfoxide, dimethylacetate, N-methyl-2-pyrrolidone, etc.) can be used; ethers (diethyl ether , Diisopropyl ether, t-butyl methyl ether, cyclopentane methyl ether, tetrahydrofuran, dioxane, etc.); aliphatic hydrocarbons (pentane, hexane, heptane, petroleum ether, etc.); aromatic hydrocarbons (benzene, toluene, xylene, mesitylene, chlorobenzene , dichlorobenzene, nitrobenzene, tetralin, etc.); halogen hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.); lower fatty acid esters (methyl acetate, ethyl acetate, etc.) esters, butyl acetate, methyl propionate, etc.); nitriles (acetonitrile, propionitrile, butyronitrile, etc.); etc. These solvents may be used alone or in two or more. In addition, the solvent can be dried using a suitable dehydrating agent or desiccant, and can be used as a non-aqueous solvent.

Although the usage-amount (reaction concentration) of a solvent is not specifically limited, It is 0.1-100 mass times with respect to a dinitro compound (4). It is preferably 0.5 to 30 times by mass, more preferably 1 to 10 times by mass.

Although the reaction temperature is not particularly limited, it is preferably in the range of -100°C to the boiling point of the solvent used, preferably -50°C to 150°C. The reaction time is usually 0.05 to 350 hours, preferably 0.5 to 100 hours.

[Production method of compound of formula (4)]

The method of synthesizing the compound of the formula (4) is not particularly limited, and examples thereof include a method of synthesizing a dinitro compound represented by the following formula (5), and further introducing a protecting group R ₁ into the NH group.

When introducing R ₁ , it is sufficient that it is a compound capable of reacting with amines. Examples include acid halides, acid anhydrides, isocyanates, epoxy compounds, oxetanes, halogenated aryl esters, and halogenated alkyl esters. Moreover, alcohols etc. which replace the hydroxyl group of an alcohol with a leaving group, such as OMs (methylsulfonyl group), OTf (trifluoromethanesulfonate group), OTs (toluenesulfonyl group), etc. can be used.

When introducing R ₁ by reaction with an acid halide, it is preferably carried out in the presence of a base. Examples of acid halides include acetyl chloride, propionyl chloride, methyl chloroformate, ethyl chloroformate, n-propyl chloroformate, i-propyl chloroformate, and chloroformic acid. n-butyl ester, i-butyl chloroformate, t-butyl chloroformate, benzyl chloroformate, 9-fluorenyl chloroformate. The base is not particularly limited if it can be synthesized, and inorganic bases such as potassium carbonate, sodium carbonate, cesium carbonate, sodium alcoholate, potassium alcoholate, sodium hydroxide, potassium hydroxide, and sodium hydride, pyridine, and dimethylamine can be used. Organic bases such as pyridine, trimethylamine, triethylamine, tributylamine, etc. The reaction solvent and reaction temperature are the same as those in the aforementioned reduction reaction of the nitro compound (4).

In the case of introducing R ₁ by reaction with an acid anhydride, examples of the acid anhydride include acetic anhydride, anhydrous propionic acid, dimethyl dicarbonate, diethyl dicarbonate, di-di-tert-butyl dicarbonate, Dibenzyl dicarbonate, etc. In order to promote the reaction, pyridine, collidine, N,N-dimethyl-4-aminopyridine or the like can be used as a catalyst. The catalyst amount is 0.0001 mol to 1 mol relative to compound (5). The reaction solvent and reaction temperature are the same as those of the above-mentioned acid halide.

When introducing R ₁ by reacting with isocyanates, examples of isocyanates include methyl isocyanate, ethyl isocyanate, n-propyl isocyanate, phenyl isocyanate and the like. The reaction solvent and the reaction temperature are the same as in the case of the above-mentioned acid halide.

When reacting with epoxy compounds or oxetane compounds and introducing R ₁ , examples of epoxy compounds or oxetane compounds include ethylene oxide, propylene oxide, 1,2 -Butene oxide, trimethylene oxide, etc. The reaction solvent and reaction temperature are the same as those of the above-mentioned acid halide.

The reaction with alcohols substituted with leaving groups such as OH OMs, OTf, and OTs of alcohols, and when introducing R ₁ , is preferably carried out in the presence of a base. Examples of the above-mentioned alcohols include methanol, ethanol, 1-propanol and the like. By mixing these alcohols with methanesulfonyl chloride, trifluoromethanesulfonyl chloride, p-toluenesulfonyl chloride, etc. Through the reaction, alcohols substituted by leaving groups of OMs, OTf, OTs, etc. can be obtained. Examples of the base, reaction solvent, and reaction temperature are the same as in the case of the above-mentioned acid halide.

When introducing R ₁ by reaction with a halogenated alkyl ester, it is preferably carried out in the presence of a base. Examples of halogenated alkyl esters include methyl iodide, ethyl iodide, n-propane, methyl bromide, ethyl bromide, n-bromopropane, and the like. As examples of the base, in addition to the aforementioned bases, metal alcoholates such as potassium tert-butoxide, sodium tert-butoxide, and the like can be used. The reaction solvent and reaction temperature are the same as in the case of the above-mentioned acid halide.

[Production method of compound of formula (5)]

The method for synthesizing the compound of the formula (5) is not particularly limited, but the pyridine of the formula (5) When the substitution positions on the ring are 2 and 4, for example, as shown in the following reaction formula 1, α-halogenated ketone having a nitro group and a ketone having a nitro group, preferably in a base reaction in the presence of . In Reaction Formula 1, X is Br, I or OTf.

As an example of the base used in the above-mentioned reaction, the bases exemplified in the above-mentioned acid halide can be used, and the reaction solvent and reaction temperature are the same as those described above.

Zinc chloride, sodium iodide, potassium iodide, tetrabutylammonium iodide and the like can be used for the purpose of promoting the speed of the above reaction.

On the other hand, when the substitution in the pyrrole ring of the compound of formula (5) is other than the 2- and 4-positions, the corresponding halogenated pyrrole and the organometallic reagent can preferably be crossed using a metal catalyst. obtained from the coupled reaction.

In Reaction Formula 2, X is Br, I, or OTf. M is B(OH) ₂ or 4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl.

The above-mentioned cross-coupling reaction (Suzuki-Miyaura reaction) preferably uses a metal complex and a ligand as a catalyst, but the reaction can also be carried out without a catalyst. Examples of metal complexes include palladium acetate, palladium chloride, palladium chloride-acetonitrile complexes, palladium-activated carbon, bis(dibenzylideneacetone)palladium, ginseng(dibenzylideneacetone)bis Palladium, bis(acetonitrile)dichloropalladium, bis(benzonitrile)dichloropalladium, CuCl, CuBr, CuI, CuCN, etc. Examples of the ligand include triphenylphosphine, tri-o-tolylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, and 1,2-bis(diphenylphosphino)ethane. , 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,1'-bis(diphenylphosphino)ferrocene, trimethyl Phosphite, triethylphosphite, triphenylphosphite, tri-tert-butylphosphine, etc.

The amount of the metal complex used may be a so-called catalyst amount, and it is sufficient to be 20 mol % or less relative to the matrix, and preferably 10 mol % or less.

<polymer>

The liquid crystal aligning agent of the present invention is a polymer obtained by using a specific diamine. As a specific example of a polymer, a polyamic acid, a polyamic acid ester, a polyimide, a polyurea, a polyamide, etc. are mentioned, for example. Among them, at least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (6) and a polyimide of an imide compound thereof is preferable.

[Chemical 21]

In the above formula (6), 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). R ₄ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ₄ is preferably a hydrogen atom, a methyl group or an ethyl group from the viewpoint of ease of imidization by heating.

In the above formula (6), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative. X1 is appropriately selected according to the solubility _of the polymer to the solvent, the coatability of the liquid crystal alignment agent, the alignment of the liquid crystal when the liquid crystal alignment film is formed, the voltage retention rate, the degree of the accumulated charge and other necessary characteristics. Among them, one kind or two or more kinds may be used.

Specific examples of X ₁ include, for example, the structures of formulae (X-1) to (X-46) disclosed on pages 13 to 14 of WO 2015/119168.

The following are the following (A-1) to (A-21) of preferable structures of X ₁ .

[Chemical 22]

Among the above-mentioned structures, (A-1) or (A-2) are particularly preferred from the viewpoint of further improvement of friction resistance, (A-4) is particularly preferred from the viewpoint of further improvement of the relaxation speed of accumulated charges, (A-15) ~(A-17) and the like are particularly preferred from the viewpoint that the liquid crystal alignment and the relaxation speed of the accumulated charge are further improved.

In formula (6), Y ₁ includes, for example, a structure in which two amine groups are removed from the diamine of the aforementioned formula (2). Wherein, Y ₁ is from the above formulae (2-1-1), (2-1-2), (2-1-3), (2-1-5), (2-1-8), (2 -1-9), (2-1-10), (2-1-11), (2-1-12) The structure of removing two amine groups is better, from (2-1-1), The structures (2-1-2), (2-1-3), (2-1-11), and (2-1-12) in which two amine groups are removed are particularly preferable.

<Other polymers (structural units)>

The liquid crystal aligning agent of the present invention may contain, in addition to the polyimide precursor having a structural unit of the above formula (6), a polyimide precursor having a structural unit represented by the following formula (7), and A polymer of at least one selected from the group consisting of polyimide which is an imide compound thereof.

In formula (7), X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative. Y ₂ is a divalent organic group derived from a diamine not having the structure of formula (1). R ₄ is as defined in the aforementioned formula (6). R ₅ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Moreover, it is preferable that at least one of the two R ₅ is a hydrogen atom.

Specific examples of X ₂ , including preferred examples, are the same as those exemplified by X ₁ in the formula (6). In addition, Y ₂ is selected according to the solubility of the polymer to the solvent, the coatability of the liquid crystal alignment agent, the alignment of the liquid crystal when the liquid crystal alignment film is formed, the voltage retention rate, the accumulated charge, etc. Two or more types are possible.

Specific examples of Y ₂ include, for example, the structure of the formula (2) disclosed on page 4 of International Publication No. 2015/119168, and the formulae (Y-1) to (Y-97), ( Structures of Y-101) to (Y-118); divalent organic groups obtained by removing two amine groups from formula (2) disclosed on page 6 of International Publication 2013/008906; as disclosed on page 8 of International Publication 2015/122413 The disclosed divalent organic group in which two amine groups are removed from the formula (1); the structure of the formula (3) disclosed on page 8 of International Publication No. 2015/060360; the structure of the formula (3) disclosed on page 8 of Japanese Laid-Open Patent Publication No. 2012-173514 A divalent organic group in which two amine groups are removed from formula (1); a divalent organic group in which two amine groups are removed from formulas (A) to (F) are disclosed on page 9 of International Publication No. 2010-050523.

The preferred structure of Y ₂ is exemplified below, but the present invention is not limited to these.

[Chemical 26]

Among the above, (B-28), (B-29) and the like are particularly preferred from the viewpoint of improving the rubbing resistance, and (B-1) to (B-3) are particularly preferred from the viewpoint of further improving the liquid crystal alignment. (B-14) to (B-18), (B-27), etc., are particularly preferred from the viewpoint of further improving the relaxation speed of the accumulated charge, and (B-26), etc. are particularly preferred from the viewpoint of further improving the voltage retention rate.

When the liquid crystal aligning agent of the present invention contains a polyimide precursor having a structural unit of formula (6) and a polyimide precursor having a structural unit of formula (7), the structural unit of formula (6) is relative to the formula The total of (6) and formula (7) is preferably 10 mol % or more, more preferably 20 mol % or more, and still more preferably 30 mol % or more.

Molecules of the polyimide precursors of the above formulas (6) and (7) The weight average molecular weight is preferably 2,000-500,000, more preferably 5,000-300,000, still more preferably 10,000-100,000.

The polyimide having a divalent group represented by the formula (1) in the main chain includes, for example, a polyimide obtained by ring-closing the aforementioned polyimide precursor. In the polyimide, the ring closure ratio of the amide acid group (also referred to as the amide imidization ratio) does not necessarily have to be 100%, and can be arbitrarily adjusted according to the application or purpose.

In terms of the method of imidizing the polyimide precursor, for example, thermal imidization in which the solution of the polyimide precursor is directly heated, or the addition of a catalyst to the solution of the polyimide precursor can be mentioned. Catalyst imidization.

<Liquid crystal alignment agent>

The liquid crystal aligning agent of this invention contains the polymer (specific polymer) obtained by the diamine which has the structure represented by Formula (1), but may contain the specific polymer of 2 or more types of different structures. In addition to the specific polymer, another polymer, that is, a polymer not having the divalent group represented by the formula (1) may be contained. For other polymers, for example, polyamides, polyimides, polyamides, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, Polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth)acrylates, and the like. When the liquid crystal aligning agent of the present invention contains another polymer, the ratio of the specific polymer relative to the total polymer component is preferably 5% by mass or more, for example, 5 to 95% by mass.

The liquid crystal aligning agent is generally in the form of a coating liquid from the viewpoint of forming a uniform thin film. The liquid crystal aligning agent of the present invention is also a coating liquid containing the aforementioned polymer component and an organic solvent for dissolving the polymer component. good. At this time, the concentration of the polymer in the liquid crystal aligning agent can be appropriately changed according to the setting of 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 mass % or more, and from the viewpoint of the storage stability of the solution, it is preferably 10 mass % or less. It is especially preferable that the concentration of the polymer is 2 to 8 mass %.

The organic solvent contained in the liquid crystal aligning agent is one that dissolves the polymer component uniformly, and is not particularly limited. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone. , dimethyl sulfoxide, γ -butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, etc. Among them, 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 of this invention can use together the solvent which improves the coatability at the time of coating a liquid crystal aligning agent or the surface smoothness of a coating film in addition to the said solvent. Specific examples of the organic solvent include, but are not limited to, the following.

For example ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1 -butanol, isoamyl 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, 1,2-ethanediol, 1,2-propanediol, 1,3-propane Diols, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-butanediol Pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, 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 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, 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 Ethyl ether, ethylene glycol monohexyl ether, 2-(hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, propylene glycol monobutyl ether, 1-(butoxyethoxy) propanol, propylene glycol Monomethyl ether acetate, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, Ethylene glycol monoethyl ether acetate, ethylene glycol 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, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, 3-methoxypropionic acid propyl ester, 3-methoxypropionic acid butyl ester, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester esters, n-butyl lactate, isoamyl lactate, solvents represented by the following formulae [D-1] to [D-3], and the like.

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

Among them, 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, diethylene glycol diethyl ether, 4-hydroxy-4 - Methyl-2-pentanone, ethylene glycol monobutyl ether or dipropylene glycol dimethyl ether are preferred. The type and content of such a solvent are appropriately selected according to the coating apparatus of the liquid crystal aligning agent, coating conditions, coating environment, and the like.

The liquid crystal aligning agent of the present invention may additionally contain components other than the polymer component and the organic solvent. In terms of such additional components, for example, adhesion assistants for improving the adhesion between the liquid crystal alignment film and the substrate, or adhesion between the liquid crystal alignment film and the sealing material, and crosslinking for improving the strength of the liquid crystal alignment film. Agents, dielectrics or conductive substances used to adjust the dielectric constant or resistance of the liquid crystal alignment film. Specific examples of these additional components include those disclosed in paragraphs 0105 to 55, paragraphs 0105 to 55, of International Publication No. WO 015/060357.

<Liquid crystal alignment film>

The liquid crystal alignment film of the present invention is obtained from the aforementioned liquid crystal alignment agent. As an example of the method for obtaining a liquid crystal alignment film, for example, a film obtained by applying a liquid crystal alignment agent in the form of a coating solution to a substrate, drying and firing, is subjected to an alignment treatment by a rubbing treatment method or a photo-alignment treatment method. method.

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

Although the coating method of the liquid crystal aligning agent is not particularly limited, it is generally industrially screen printing, offset printing, flexographic printing, inkjet method, and the like. As for other coating methods, there are a dipping method, a roll coating method, a slit coating method, a spin coating method, a spraying method, and the like, and these can be used according to the purpose.

After coating the liquid crystal aligning agent on the substrate, the solvent is evaporated and fired by heating means such as a hot plate, a thermal cycle oven, and an IR (infrared) oven. The drying and firing steps after coating the liquid crystal aligning agent can select any temperature and time. Usually, in order to fully remove the contained solvent, for example, baking is performed at 50-120 degreeC for 1-10 minutes, and the conditions of baking at 150-300 degreeC for 5-120 minutes are mentioned after that.

If the thickness of the liquid crystal alignment film after firing is too thin, there will be liquid crystal display. The reliability of the display device is reduced, so 5~300nm is preferable, and 10~200nm is more preferable.

The liquid crystal alignment film of the present invention is suitable for a liquid crystal display element of a lateral electric field method such as an IPS method or an FFS method, and is particularly suitable for a liquid crystal alignment film of a liquid crystal display element of the FFS method.

<Liquid crystal display element>

The liquid crystal display element of this invention manufactures a liquid crystal cell by a known method after obtaining the board|substrate with the liquid crystal aligning film obtained by the said liquid crystal aligning agent, and manufactures an element using this liquid crystal cell.

As an example of the manufacturing method of a liquid crystal cell, the liquid crystal display element of a passive matrix structure is demonstrated as an example. In addition, it may be an element of an active matrix structure in which switching elements such as TFT (Thin Film Transistor) are provided in each pixel portion constituting an image display.

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, which can be ITO electrodes, for example, are patterned so that the desired image can be displayed. Next, an insulating film is provided on each substrate to cover the common electrode and the segment electrode. The insulating film may be, for example, a film composed of SiO ₂ -TiO ₂ formed by a sol-colloid method. Next, a liquid crystal alignment film was formed on each substrate under the general conditions described above.

Next, a UV-curable sealing material is arranged at a designated place on one of the two substrates forming the liquid crystal alignment film, and liquid crystals are further arranged at a designated number of places on the surface of the liquid crystal alignment film. After laminating the other substrate with the film facing each other, the liquid crystal is spread out in front of the liquid crystal alignment film by pressing, and then ultraviolet rays are irradiated to the entire surface of the substrate to harden the sealing material to obtain a liquid crystal cell.

Or after the liquid crystal alignment film is formed on the substrate, when the sealing material is arranged in a designated place on a substrate, the openings that can be filled with liquid crystal are set in advance from the outside, and after the substrates are attached, the liquid crystal material is injected through the openings provided on the sealing material. In a liquid crystal cell, this opening part was sealed with an adhesive agent next, and the liquid crystal cell was obtained. The injection of the liquid crystal material may be a vacuum injection method or a method utilizing capillary phenomenon in the atmosphere.

In any of the above methods, in order to ensure the space for filling the liquid crystal cell with the liquid crystal material, a substrate is provided with columnar protrusions, or spacers are scattered on a substrate, or spacers are mixed into the sealing material, or a combination of these The means of waiting is better.

The above-mentioned liquid crystal material includes, for example, nematic liquid crystal and smectic liquid crystal, among which nematic liquid crystal is preferred, and either a positive liquid crystal material or a negative liquid crystal material may be used. Next, the setting of the polarizing plate is performed. Specifically, it is preferable to bond a pair of polarizing plates to the opposite sides of the liquid crystal layers of the two substrates.

Moreover, when using the liquid crystal aligning agent of this invention, the liquid crystal aligning film and liquid crystal display element of this invention are not limited to the above description, and can also be produced by other conventional methods. The steps up to obtaining a liquid crystal display element from a liquid crystal aligning agent are shown, for example, in paragraphs 0074 to 19 of paragraphs 0074 to 19 of Japanese Patent Laid-Open No. 2015-135393, and the like.

[Example]

Hereinafter, the present invention will be specifically described with reference to Examples and the like. In addition, the present invention is not limited to these embodiments. The abbreviations of the compounds used below, and the property evaluation methods are as follows.

[Chemical 31]

In the above formula, Boc is a group represented by the following formula.

[Chemical 32]

<Organic solvent>

NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone,

BCS: Butyl Cellosolve

<Additive>

LS-4668: 3-Glycidoxypropyltriethoxysilane

<Crosslinking agent>

(Measurement of ¹ H-NMR)

Apparatus: Varian NMR system 400NB (400MHz) (manufactured by Varian), and JMTC-500/54/SS (500MHz) (manufactured by JEOL)

Assay solvent: CDCl ₃ (deuterated chloroform), DMSO-d ₆ (deuterated dimethyl sulfoxide)

Reference materials: TMS (tetramethylsilane) (δ: 0.0 ppm, ¹ H) and CDCl ₃ (δ: 77.0 ppm, ¹³ C)

<Molecular weight measurement of polyimide precursor and polyimide>

The measurement was performed as follows using a room temperature colloidal permeation chromatography (GPC) apparatus (GPC-101) (manufactured by Showa Denko Corporation) and columns (KD-803, KD-805) (manufactured by Shodex Corporation).

Column temperature: 50℃

Eluent: N,N'-dimethylformamide (lithium bromide-hydrate (LiBr.H2O) as an additive is 30 mmol/L (liter), phosphoric acid. Anhydrous crystal (o-phosphoric acid) is 30 mmol/L, tetrahydrofuran (THF) is 10ml/L)

Flow rate: 1.0ml/min

Standard sample for calibration line preparation: TSK standard polyethylene oxide (molecular weight; about 900,000, 150,000, 100,000, and 30,000, manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight; about 12,000, 4,000, and 1,000, Polymer Laboratories Ltd.).

<Viscosity measurement>

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

<Synthesis of diamine compound (DA-1)>

[Chemical 34]

Zinc chloride (120.3 g, 882 mmol) was added to a 3 L (liter) four-necked flask, the temperature was raised to 100° C., and vacuum drying was performed with an oil pump for 1 hour. Then, under a nitrogen atmosphere at room temperature, toluene (460 g), diethylamine (45.0 g, 615 mmol), t-butanol (46.4 g, 626 mmol), 2-bromo-4-nitrophenethyl were sequentially added Ketone (100.0 g, 410 mmol) and 4-nitroacetophenone (104.2 g, 631 mmol) were stirred at room temperature for 3 days. After confirming the completion of the reaction by HPLC (high-speed liquid chromatography), a 5% sulfuric acid aqueous solution (400 g) was added for neutralization, and the mixture was stirred at room temperature for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with toluene (200 g), pure water (300 g), and methanol (200 g), and then dried to obtain crude crystals. After the obtained crude crystals were completely dissolved in tetrahydrofuran (1340 g) at 60°C, ethanol (1340 g) was added, and the mixture was stirred at 5°C for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with ethanol (200 g), and then dried to obtain powder crystals of compound (1) (yield 63 g, yield 45%).

1H-NMR (DMSO-d ₆ ): 8.40-8.36 (4H, m), 8.28-8.24 (4H, m), 3.53 (4H, s)

[Chemical 35]

Compound (1) (65.8 g, 200 mmol), ammonium acetate (84.5 g, 1100 mmol), and acetic acid (855 g) were added to a 2 L four-necked flask, the temperature was raised to 120° C., and the mixture was stirred under reflux for 3 hours. After confirming the completion of the reaction by HPLC (high-speed liquid chromatography), the reaction solution was added to cold water (4000 g) and stirred for 1 hour. The precipitated crystals were filtered under reduced pressure, reslurried and washed with acetonitrile (100 g), and then dried to obtain powder crystals of compound (2) (yield 53 g, yield 78%).

1H-NMR (DMSO-d ₆ ): 11.8 (1H, br), 8.30-8.26 (4H, m), 8.11-8.07 (4H, m), 7.04 (2H, s)

A mixture of compound (2) powder (22 g, 72.4 mmol), 5 mass % palladium carbon (Pd/C) (50% aqueous type), characteristic egret activated carbon (2.0 g), and dioxane (220 g) was crystallized Stirring was performed at 80°C for 8 hours under hydrogen pressurization. After completion of the reaction, the catalyst was filtered, concentrated, 2-propanol (300 g) was added, and the mixture was stirred at 5°C for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with methanol (50 g), and then dried to obtain powder of DA-1. Final crystallization (yield 13 g, yield 69%).

1H-NMR (DMSO-d ₆ ): 10.6(1H,s), 7.39-7.35(4H,m), 6.57-6.53(4H,m), 6.19(2H,s), 5.01(4H,s)

[Synthesis Example 1]

After adding DA-1 (2.49 g, 10.0 mmol) to a 100 ml four-neck flask with a stirring device and a nitrogen introduction tube, NMP 29.0 g was added, and stirring was performed to dissolve it while feeding nitrogen. CA-2 (0.98 g, 5.0 mmol) and 3.6 g of NMP (additional amount 1 in Table 1) were added to this solution while stirring, and then the solution was stirred at 25°C for 1 hour. Then, CA-1 (0.87 g, 4.0 mmol) was added, and 3.6 g of NMP (additional amount 2 in Table 1) was added, followed by stirring at 50° C. for 12 hours to obtain a resin with a solid content concentration of 12% by mass. Polyamide solution (PAA-A1). The viscosity of the polyamide acid solution is 300mPa. s.

[Synthesis Examples 2 to 16]

Using the tetracarboxylic acid dianhydride component, the diamine component, and the amount of NMP shown in Table 1, it was carried out in the same manner as in Synthesis Example 1 except for the reaction temperature shown in Table 1, respectively, and the solid content concentration shown in Table 1 was obtained. And the viscosity of the polyamide acid solution (PAA-A2) ~ (PAA-A9) and the polyamide acid solution (PAA-B1) ~ ((PAA-B7).

[Synthesis Example 17]

DA-6 (4.03 g, 16.5 mmol), DA-7 (3.59 g, 9.0 mmol), and DA-8 (2.50 g, 4.5 mmol) were added to a 200 ml four-necked flask with a stirring device and a nitrogen introduction tube. After that, 102.1 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. CA-4 (4.37 g, 19.5 mmol) and 12.8 g of NMP were added to this solution while stirring, and the solution was stirred at 40°C for 3 hours. mix. Then, CA-2 (1.71 g, 8.7 mmol) and 12.8 g of NMP were added under the condition of 25° C., and then stirring was further performed for 12 hours to obtain a polyamic acid solution with a resin solid content concentration of 15 mass %. The viscosity of the polyamide acid solution is 820mPa. s.

80.0 g of this polyamic acid solution was dispensed, and after adding 70.0 g of NMP, 6.8 g of acetic anhydride and 1.8 g of pyridine were added, and the reaction was carried out at 50° C. for 3 hours. The reaction solution was poured into 555.0 g of methanol, and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 60°C to obtain a powder of polyimide. The imidization rate of this polyimide was 75%. 586.7 g of NMP was added to 80.0 g of the obtained polyimide powder, and the mixture was stirred and dissolved at 50° C. for 20 hr to obtain a polyimide solution (SPI-B8).

[Synthesis Example 18]

DA-6 (2.20g, 9.0mmol), DA-13 (1.62g, 15.0mmol), and DA-14 (2.45g, 6.0mmol) were added to a 100ml four-necked flask with a stirring device and a nitrogen introduction tube. Then, 81.8 g of NMP was added, and it was made to melt|dissolve by stirring, feeding nitrogen. CA-4 (6.52 g, 29.10 mmol) was added to this solution while stirring, and 9.1 g of NMP was added, followed by stirring at 40° C. for 24 hours to obtain a polyamic acid solution (PAA) having a resin solid content concentration of 12% by mass. -B9). The viscosity of the polyamide acid solution is 386mPa. s.

[Synthesis Example 19]

DA-1 (2.62g, 10.5mmol), DA-2 (1.39g, 7.0mmol), and After DA-3 (3.49 g, 17.5 mmol), 70.0 g of NMP was added, and it was dissolved by stirring while feeding nitrogen. CA-2 (1.70 g, 8.7 mmol) and 9.5 g of NMP were added to this solution with stirring, followed by stirring at 25°C for 1 hour. Then, CA-3 (6.57 g, 26.3 mmol) was added, and NMP 9.5 g was added, followed by stirring at 50° C. for 12 hours to obtain a polyamic acid solution (PAA-A10) having a resin solid content concentration of 12 mass %. ). The viscosity of the polyamide acid solution is 375mPa. s.

[Synthesis Example 20]

DA-1 (1.12 g, 4.5 mmol), DA-2 (0.59 g, 3.0 mmol), and DA-3 (1.49 g, 7.5 mmol) were added to a 100 ml four-necked flask with a stirring device and a nitrogen introduction tube. After that, 31.0 g of a mixed solvent of NMP:GBL=1:1 was added, and the mixture was stirred and dissolved while feeding nitrogen. CA-2 (1.15 g, 5.9 mmol) and 10.0 g of a mixed solvent of NMP:GBL=1:1 were added to this solution while stirring, and the mixture was stirred at 25°C for 1 hour. After that, CA-5 (2.60 g, 8.8 mmol) was added, 10.0 g of a mixed solvent of NMP:GBL=1:1 was added, and the mixture was further stirred at 50° C. for 12 hours to obtain a polymer with a resin solid content concentration of 12% by mass. Amino acid solution (PAA-A12). The viscosity of the polyamide acid solution is 200mPa. s.

[Examples 1 to 22] and [Comparative Examples 1 to 6]

The polyimide solutions obtained in Synthesis Examples 1 to 16 and 18, and the polyimide solution obtained in Synthesis Example 17, were prepared as polymer 1 and polymer 2 shown in Table 2-1 and Table 2-2 below. The solution obtained by mixing the The NMP solution containing 1% by weight of NMP, GBL, BCS, LS-4668, and the NMP solution containing 3% by weight of AD-1 were added to make the compositions shown in Table 2-1 and Table 2-2. Stirring was performed for 2 hours, and the liquid crystal aligning agents of Examples 1-22 and Comparative Examples 1-6 were obtained.

<Production of liquid crystal display element by rubbing method>

A glass substrate with a size of 30 mm x 35 mm and an electrode with a thickness of 0.7 mm was prepared. An IZO electrode having a solid pattern that constitutes a counter electrode as a first layer was formed on the substrate. On the opposite electrode of the first layer, a SiN (silicon nitride) film formed by a CVD method is formed as a second 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, a comb-shaped pixel electrode formed by patterning an IZO film is arranged as a third layer, and two pixels of a first pixel and a second pixel are formed. The size of each pixel is 10 mm in length and 5 mm in width. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the function of the SiN film of the second layer.

The pixel electrodes of the third layer, as shown in FIG. 3 described in Japanese Patent Application Laid-Open No. 2014-77845, have a plurality of “ㄑ characters” with curved central parts. The shape of the electrode elements constituted by the comb-like shape. The width of each electrode element in the width direction was 3 μm, and the interval between the electrode elements was 6 μm. The pixel electrode that forms each pixel is composed of a plurality of “U-shaped”-shaped electrode elements that are curved in the center part, and therefore the shape of each pixel is not rectangular, but has a similar electrode element that is curved in the center part. Bold "ㄑ" shape. In addition, each pixel is divided up and down with its central curved portion as a boundary, and has a first area on the upper side of the curved portion and a second area on the lower side.

When the first region and the second region of each pixel are compared, the direction in which the electrode elements constituting the pixel electrodes are formed is different. That is, when the rubbing direction of the liquid crystal alignment film described later is used as a reference, in the first region of the pixel, the electrode elements of the pixel electrode are formed at an angle of +10° (clockwise), and in the second region of the pixel, The electrode elements of the pixel electrode are formed so as to exhibit an angle of -10° (clockwise). The first region and the second region of each pixel are configured such that the directions of the rotation (plane switching) in the substrate plane of the liquid crystal induced by applying a voltage between the pixel electrode and the counter electrode are opposite to each other.

Next, the liquid crystal aligning agent was filtered through a filter with a pore size of 1.0 μm , and then spin-coated on the above-mentioned substrate with electrodes and the backside of the opposite substrate, where an ITO film was formed and a columnar space with a height of 4 μm was formed. The glass substrate of the piece. Next, after drying on a hot plate at 80° C. for 5 minutes, firing was performed at 230° C. for 20 minutes to obtain a polyimide film having a thickness of 60 nm on each substrate. The surface of the polyimide film was subjected to a rubbing treatment with a rayon cloth under the conditions of a roll diameter of 120 mm, a drum rotation speed of 500 rpm, a table moving speed of 30 mm/sec, and a rubbing cloth press-in pressure of 0.3 mm, and then was subjected to rubbing treatment in pure water. Ultrasonic irradiation for 1 minute and drying at 80°C for 10 minutes.

Using the above-mentioned two types of substrates with liquid crystal and alignment film, the rubbing directions were antiparallel to each other, and the liquid crystal injection port was left to seal the surroundings, and an empty cell with a cell gap of 3.8 μm was produced. In this empty cell, after the liquid crystal (Merck & Co. make, MLC-3019,) was vacuum-injected at room temperature, the injection port was sealed to prepare an antiparallel alignment liquid crystal cell. The obtained liquid crystal cell constitutes an FFS mode liquid crystal display element. Then, the liquid crystal cell was heated at 120° C. for 1 hour, and was used for each of the following evaluations after being left to stand overnight.

<Evaluation of afterimage removal time>

The evaluation of image sticking was performed using the following optical systems and the like. The liquid crystal cell to be fabricated is placed between two polarizers arranged in such a way that the polarization axes are perpendicular to each other, and the LED backlight is made to emit light when no voltage is applied to adjust the liquid crystal cell so that the brightness of the transmitted light is minimized. The configuration angle of the cells. Next, a V-T curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to this liquid crystal cell, and the AC voltage at which the relative transmittance reached 23% was calculated as a driving voltage.

In the evaluation of image sticking, a DC voltage of 1 V was applied for 30 minutes while driving the liquid crystal cell by applying an AC voltage at a frequency of 30 Hz to achieve a relative transmittance of 23%. Then, the value of the applied DC voltage was set to 0 V, and only the application of the DC voltage was stopped, and the driving was continued for 15 minutes in this state.

Afterimage evaluation is performed from the point of time when the DC voltage is started to be applied The time taken for the relative transmittance to decrease to 30% or less until 30 minutes elapsed was quantified. When the relative transmittance decreased to 30% or less within 5 minutes, it was evaluated as "○", and within 6 to 30 minutes, it was evaluated as "△". When it took more than 30 minutes until the relative transmittance decreased to 30% or less, it was evaluated as "X" because the afterimage could not be eliminated. On the other hand, the evaluation of image sticking according to the above method is carried out under the temperature condition of the state of the temperature of the liquid crystal cell of 23°C.

<Evaluation of the degree of flicker immediately after driving>

The fabricated liquid crystal cell was placed between two polarizers arranged so that the polarization axes were perpendicular to each other, and the LED backlight was made to emit light in the state where no voltage was applied, so that the brightness of the transmitted light was minimized. The configuration angle of the cells. Next, a V-T curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to this liquid crystal cell, and the AC voltage at which the relative transmittance reached 23% was calculated as a driving voltage.

In the measurement of flickering degree, the pre-lit LED backlight was temporarily turned off, and after 72 hours of shading, the LED backlight was turned on again. After the liquid crystal cell was driven for 60 minutes, the flicker amplitude was tracked. The flicker amplitude was read by the transmitted light of the LED backlight passing through the two polarizers and the liquid crystal cell in between through a data collection/data logger switch unit 34970A (manufactured by Agilent Technologies) connected to a photodiode and an I-V conversion amplifier. The degree of flicker is calculated by the following formula.

Flicker degree (%)={flicker amplitude/(2×z)}×100

In the above formula, z is a value read by the data acquisition/data logger switch unit 34970A at the time of driving with an AC voltage at a frequency of 30 Hz with a relative transmittance of 23%.

The degree of flicker was evaluated as "○" when the degree of flicker remained less than 3% until 60 minutes elapsed from the time when the LED backlight was turned on and the application of the AC voltage was started. When the flicker level reached 3% or more in 60 minutes, it was evaluated as "X".

And the evaluation of the degree of flicker according to the above method was carried out under the temperature condition of the state where the temperature of the liquid crystal cell was 23°C.

<Evaluation Result>

Table 3 shows the evaluation results of the afterimage removal time and the degree of flicker immediately after driving of the liquid crystal display elements using the liquid crystal aligning agents of Examples 1 to 22 and Comparative Examples 1 to 5.

<Production of liquid crystal display element by photo-alignment method>

Next, the liquid crystal aligning agent was filtered through a filter with a pore size of 1.0 μm , and then spin-coated on the above-mentioned substrate with electrodes and the backside of the opposite substrate, where an ITO film was formed and a columnar space with a height of 4 μm was formed. The glass substrate of the piece. Next, after drying on a hot plate at 80° C. for 5 minutes, firing was performed at 230° C. for 30 minutes to obtain a polyimide coating film having a thickness of 100 nm on each substrate. The coating film surface was irradiated with 300 mJ/cm ² of ultraviolet rays having a wavelength of 254 nm and a linearly polarized light with an extinction ratio of 26:1 through a polarizing plate. The substrate was heated on a hot plate at 230° C. for 30 minutes to obtain a substrate with a liquid crystal alignment film. Using the above-mentioned two substrates as a set, a sealant was printed on the substrates, and the other substrate was bonded so that the liquid crystal alignment film faces were opposite to each other and the alignment direction was 0°, and then the sealant was cured to produce an empty cell. MLC-7026-100 (manufactured by Merck & Co., Ltd.) of negative liquid crystal was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. Then, the obtained liquid crystal cell was heated at 110 degreeC for 1 hour, and was used for each following evaluation after standing overnight.

<Evaluation of afterimage removal time>

As in the case of the liquid crystal display element of the rubbing method, the evaluation of image sticking was performed using the optical system and the like of the liquid crystal display element of the photo-alignment method produced above.

In addition, unlike the case of the liquid crystal display element of the rubbing method, the image sticking evaluation was quantified as the time taken for the relative transmittance to decrease to 23% until 30 minutes elapsed from the time when the DC voltage was applied. When the relative transmittance decreased to 23% within 5 minutes, it was evaluated as "○", and within 6 to 30 minutes, it was evaluated as "△". When the relative transmittance decreased to 23% for more than 30 minutes, the afterimage could not be eliminated, and it was defined as "X".

<Evaluation of the degree of flicker immediately after driving>

As in the case of the liquid crystal display element of the rubbing method, the optical system and the like of the liquid crystal display element of the photo-alignment method produced above were used to evaluate the residual image. estimate.

<Evaluation Result>

For the liquid crystal display element using the liquid crystal aligning agent obtained in Example 19 and Comparative Example 6, Table 4 shows the evaluation results of the afterimage erasing time and the degree of flicker immediately after driving.

As can be seen from Tables 3 and 4 above, it can be seen that the liquid crystal display element using the liquid crystal aligning agent of the example of the present invention has a fast relaxation of the accumulated charge, and is less likely to cause a flicker transition immediately after the start of driving.

[Industrial applicability]

The liquid crystal aligning agent using the novel polymer of the present invention is widely used in liquid crystal display devices of vertical electric field methods such as TN mode and VA mode, and especially lateral electric field modes such as IPS mode and FFS mode.

In addition, the entire contents of the specification, the scope of application, and the abstract of Japanese Patent Application No. 2016-010996 filed on January 22, 2016 and Japanese Patent Application No. 2016-110237 filed on June 1, 2016 are incorporated herein by reference as The disclosure of the specification of the present invention.

Claims (14)

A liquid crystal aligning agent characterized by containing a polymer obtained from a diamine having a structure represented by the following formula (1) and an organic solvent,

(R ₁ is hydrogen, a fluorine atom, a cyano group, a hydroxyl group, or a monovalent organic group, * is a site for bonding to other groups, and any hydrogen atom of the benzene ring may be substituted by a monovalent organic group). The liquid crystal aligning agent according to claim 1, wherein the polymer is a polyimide precursor of a polycondensate of a diamine and a tetracarboxylic dianhydride having a structure represented by the formula (1) and an imide thereof A polymer of at least one selected from the group consisting of polyimides of amines. The liquid crystal aligning agent according to claim 1 or 2, wherein the diamine is represented by the following formula (2),

(The definition of R ₁ is the same as that of the aforementioned formula (1), the two R ₂ are independent of each other, and are a single bond or the structure of the following formula (3), n is an integer of 1 to 3, and any hydrogen atom of the benzene ring can be replaced by a monovalent organic group substitution)

(R ₃ is a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) ₁ -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO- Organic group (1 and m are integers of 1 to 5), * ₁ is a site bonded to the benzene ring in the formula (2), and * ₂ is a site bonded to the amine group in the formula (2). The liquid crystal aligning agent according to claim 2, wherein the polyimide precursor has a structural unit represented by the following formula (6),

(X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine having the structure of the aforementioned formula (1), R ₄ is a hydrogen atom or a carbon number of 1 to 5 the alkyl group). The liquid crystal aligning agent according to claim 4, wherein, in the aforementioned formula (6), X ₁ is at least one selected from the group consisting of the structures of the following formulas (A-1) to (A-21),

The liquid crystal aligning agent according to claim 4, wherein the polymer having the structural unit represented by the aforementioned formula (6) is contained in an amount of 10 mol % or more of the total polymer contained in the liquid crystal aligning agent. The liquid crystal aligning agent according to claim 1 or 2, wherein the organic solvent contains at least 1 selected from the group consisting of 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether kind. A liquid crystal alignment film characterized by being obtained by the liquid crystal alignment agent according to any one of claims 1 to 7. A liquid crystal display element comprising the liquid crystal alignment film of claim 8. The liquid crystal display element according to claim 9, wherein the liquid crystal display element is of a lateral electric field drive type. A polymer characterized by a polyimide precursor of a polycondensate of a diamine and a tetracarboxylic dianhydride having a structure represented by the following formula (1) and a polyimide of an imide compound thereof At least 1 species selected from the group,

(* is a site that is bonded to other groups, R ₁ is hydrogen, a fluorine atom, a cyano group, a hydroxyl group, or a monovalent organic group, and the aforementioned monovalent organic group is an alkyl group, an alkenyl group, an alkane group having a carbon number of 1 to 10 oxy, fluoroalkyl, fluoroalkenyl, or fluoroalkoxy). The polymer according to claim 11, wherein the diamine is represented by the following formula (2),

(R ₁ is hydrogen, a fluorine atom, a cyano group, a hydroxyl group, or a monovalent organic group, and the aforementioned monovalent organic group is an alkyl group, an alkenyl group, an alkoxy group, a fluoroalkyl group, and a fluoroalkenyl group having a carbon number of 1 to 10 , or a fluoroalkoxy group, two R ₂ are each independently, a single bond or the structure of the following formula (3), n is an integer from 1 to 3, and any hydrogen atom of the benzene ring can be substituted by a monovalent organic group)

(R ₃ is a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) ₁ -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO- Organic group (1 and m are integers of 1 to 5), * ₁ is a site bonded to the benzene ring in the formula (2), and * ₂ is a site bonded to the amine group in the formula (2). The polymer according to claim 11 or 12, wherein the polyimide precursor is represented by the following formula (6),

(X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, Y ₁ is a divalent organic group derived from a diamine having the structure of the aforementioned formula (1), R ₄ is a hydrogen atom or a carbon number of 1 to 5 the alkyl group). The polymer according to claim 13, wherein, in the aforementioned formula (6), X ₁ is at least one selected from the group consisting of the structures of formulas (A-1) to (A-21) described in claim 5 1 type.