JP7428177B2 - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal display element and diamine - Google Patents

Description

The present invention relates to polymers, liquid crystal alignment agents, liquid crystal alignment films, and liquid crystal display elements used in liquid crystal display elements, and novel diamines used therein.

Various driving methods have been developed for liquid crystal display elements, with different electrode structures, physical properties of liquid crystal molecules used, manufacturing processes, etc. For example, TN (twisted nematic) type, STN (super-twisted nematic) type, VA ( vertical alignment) type, MVA (multi-domain vertical alignment) type, IPS (in-plane switching) type, FFS (fringe field switching) type, PSA (polymer R-sustained alignment) type liquid crystal display elements are known. .
These liquid crystal display elements include a liquid crystal alignment film for aligning liquid crystal molecules. Films made of polymers such as polyamic acid, polyimide, and polysiloxane are generally used as materials for liquid crystal alignment films because they have good properties such as heat resistance, mechanical strength, and affinity with liquid crystals. ing.

In recent years, there has been an increasing demand for higher image quality in liquid crystal display elements. In particular, in medical device displays and liquid crystal televisions, so-called "afterimages", in which images remain after long-term operation, have become a major issue, and there is a strong demand for reducing afterimages. From the viewpoint of further improving the quality of liquid crystal display elements, it is desired to obtain a liquid crystal display element that is less likely to cause afterimages than before.

In view of this situation, liquid crystal alignment films and liquid crystal alignment agents that provide liquid crystal display elements with excellent afterimage reduction are known (for example, see Patent Document 1, Patent Document 2, and Patent Document 3).

In addition, liquid crystal display elements for the above applications are required to have characteristics that can withstand long-term use in harsh environments, and Patent Document 4 discloses that a liquid crystal aligning agent containing a specific compound is used when exposed to a backlight for a long time. It is disclosed that a liquid crystal alignment film with a small decrease in voltage holding rate can be obtained even after the application, and a highly reliable liquid crystal display element can be obtained.

International Publication No. 2016/063834 pamphlet International Publication No. 2015/060366 pamphlet Japanese Patent Application Publication No. 2018-054761 International Publication No. 2010/074269 pamphlet

Furthermore, as so-called touch panel type liquid crystal display elements have become widespread, users frequently apply strong pressing force to the display elements with their fingers. At this time, the spacer existing inside the liquid crystal display element moves within the liquid crystal display element and rubs against the liquid crystal alignment film. The liquid crystal alignment film that is stressed by the spacer is unable to regulate the alignment of the liquid crystal, and even though the liquid crystal display element is displaying black, for example, light escapes from the periphery of the spacer and appears as a bright spot. The problem is that it is displayed.

The configurations of liquid crystal alignment agents that have been proposed in the past cannot necessarily be said to be able to achieve all of the above-mentioned problems. The present invention has been made based on the above-mentioned circumstances, and its purpose is to improve reliability by minimizing the occurrence of afterimages and minimizing bright spots even when physical friction such as rubbing by a spacer occurs. An object of the present invention is to provide a liquid crystal display element with high performance. Another object of the present invention is to provide a liquid crystal alignment film with high film strength suitable for such a liquid crystal display element and a liquid crystal aligning agent thereof.

Furthermore, in order to increase the effective pixel area of recent liquid crystal display elements, it is required to further reduce the so-called frame area where no pixels are formed at the peripheral outer edge of the substrate. As the frames of panels become narrower, the sealant used when bonding two substrates to create a liquid crystal display element comes to be applied onto a polyimide-based liquid crystal alignment film. Since there is no group, a covalent bond is not formed between the sealant and the surface of the liquid crystal alignment film, resulting in insufficient adhesion between the substrates. Therefore, it is a challenge to improve the adhesiveness (adhesion) between the polyimide-based liquid crystal alignment film and the sealant or substrate.

As a result of intensive studies to solve the above problems, the present inventors discovered that various properties can be simultaneously improved by introducing a specific structure into the polymer contained in the liquid crystal aligning agent. Completed the invention. The present invention is based on this knowledge and has the following gist.
1. A liquid crystal aligning agent containing a polymer obtained from a diamine having a structure represented by the following formula (1).

A is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a benzyl group, p-methoxybenzyl group, an alkoxy group having 1 to 3 carbon atoms, an acetyl group, a benzoyl group, a t-butyloxycarbonyl group, 9-fluorenyl It represents a methoxycarbonyl group or an R ₁ R ₂ R ₃ Si group, and R ₁ , R ₂ and R ₃ each independently represent an alkyl group having 1 to 3 carbon atoms or a phenyl group.

According to the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal display element and a liquid crystal aligning film providing the same, which have less generation of afterimages and can minimize bright spots even when physical friction such as rubbing by a spacer occurs.

According to the liquid crystal aligning agent of the present invention, a liquid crystal aligning film having excellent adhesiveness with a sealant can be obtained. By using this liquid crystal alignment film, a liquid crystal display element with excellent adhesion between substrates and strong resistance to impact can be obtained. The mechanism by which the adhesion with the sealant improves is not necessarily clear, but the hydroxy groups and methoxy groups possessed by specific diamines, or the hydroxy groups generated when protective groups are removed by heating, are It is thought that the adhesion between the liquid crystal alignment film and the sealant improves due to the interaction between such groups and the functional groups in the sealant.

The liquid crystal aligning agent of the present invention is a liquid crystal aligning agent containing a polymer (hereinafter also referred to as a specific polymer) obtained from a diamine having a structure represented by the above formula (1). Each condition will be explained in detail below.

<Diamine with specific structure>
The polymer of the present invention is a polymer obtained from a diamine having the structure of formula (1) above.
Specific examples of the diamine of the above formula (1) include, but are not limited to, the following. Among these, (1-1), (1-2), and (1-3) are particularly preferred from the viewpoint of alleviating accumulated charges.

<Polymer>
The polymer of the present invention is a polymer obtained using the above diamine. Specific examples include polyamic acid, polyamic acid ester, polyimide, polyurea, polyamide, etc., but from the viewpoint of use as a liquid crystal aligning agent, a polyimide precursor containing a structural unit represented by the following formula (6), It is more preferable to use at least one selected from polyimide, which is an imidized product thereof.

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), and R ₄ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. From the viewpoint of ease of imidization by heating, R ₄ is preferably a hydrogen atom, a methyl group, or an ethyl group.

<<Tetracarboxylic dianhydride>>
X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative, and its structure is not particularly limited. In addition, X ₁ in the polyimide precursor is required for the solubility of the polymer in solvent, the coatability of the liquid crystal alignment agent, the alignment of the liquid crystal when used as a liquid crystal alignment film, voltage holding rate, accumulated charge, etc. They are appropriately selected depending on the degree of properties, and may be one type, or two or more types may be mixed in the same polymer.
Specific examples of X ₁ include the structures of formulas (X-1) to (X-46) listed in sections 13 to 14 of International Publication No. 2015/119168.
Preferred structures of X ₁ are shown below, but the present invention is not limited thereto.

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

<<Polymer (other structural units)>>
The polyimide precursor containing the structural unit represented by the formula (6) is at least one selected from the structural unit represented by the following formula (7) and a polyimide which is an imidized product thereof, within a range that does not impair the effects of the present invention. It may contain one type.

In formula (7), 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 ₅ has the same definition as R ₄ in formula (6) above, and R ₆ represents 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 ₆ 's is a hydrogen atom.

Specific examples of X ₂ include the same structures as those exemplified for X ₁ in formula (6), including preferred examples. Further, Y ₂ in the polyimide precursor is a divalent organic group derived from a diamine that does not include the structure of formula (1) in the main chain direction, and its structure is not particularly limited. In addition, _Y2 is determined depending on the degree of required properties, such as the solubility of the polymer in a solvent, the applicability of the liquid crystal alignment agent, the alignment of the liquid crystal when used as a liquid crystal alignment film, the voltage holding rate, and the accumulated charge. They may be selected as appropriate, and one type or two or more types may be mixed in the same polymer.

If we were to give specific examples of Y ₂ , the structure of formula (2) published in section 4 of International Publication No. 2015/119168, and the structure of formula (Y-1) - published in sections 8 to 12 Structures of (Y-97), (Y-101) to (Y-118): Divalent organic compounds obtained by removing two amino groups from formula (2), listed in Section 6 of International Publication No. 2013/008906 Group: Divalent organic group obtained by removing two amino groups from formula (1) published in International Publication No. 2015/122413, Section 8; Formula (3) listed in International Publication Publication 2015/060360, Section 8 Structure: A divalent organic group obtained by removing two amino groups from the formula (1) described in section 8 of Japanese Patent Publication No. 2012-173514; Formula published in section 9 of International Publication No. 2010-050523 Examples include divalent organic groups obtained by removing two amino groups from (A) to (F).
Preferred structures of _Y2 are shown below, but the present invention is not limited thereto.

Among the above structures, structures such as (B-28) and (B-29) are particularly preferable from the viewpoint of further improving film strength, and structures such as (B-1) to (B-3) are particularly preferable from the viewpoint of further improving the film strength. Particularly preferred from the viewpoint of further improvement, (B-14) to (B-18) and (B-27), etc. are particularly preferred from the viewpoint of further improvement of the relaxation rate of accumulated charge, and (B-26) etc. is preferable from the viewpoint of further improving the voltage holding ratio.
When a polyimide precursor containing a structural unit represented by formula (6) simultaneously contains a structural unit represented by formula (7), the structural unit represented by formula (6) is a combination of formula (6) and formula (7). It is preferably 10 mol% or more, more preferably 15 mol% or more, particularly preferably 20 mol% or more based on the total of (7).

The weight average molecular weight of the polyimide precursor used in the present invention is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and even more preferably 10,000 to 100,000. be.

Examples of the polyimide having a divalent group represented by formula (1) in its main chain include polyimides obtained by ring-closing the polyimide precursors described above. In this polyimide, the ring closure rate (also referred to as imidization rate) of the amic acid group does not necessarily have to be 100%, and can be arbitrarily adjusted depending on the use and purpose.
Examples of methods for imidizing the polyimide precursor include thermal imidization, in which the solution of the polyimide precursor is directly heated, and catalytic imidization, in which a catalyst is added to the solution of the polyimide precursor.

The liquid crystal aligning agent of the present invention is a composition containing the above-mentioned specific polymer and an organic solvent, and may contain two or more types of specific polymers having different structures. In addition, the liquid crystal aligning agent of the present invention may contain a polymer other than the specific polymer (hereinafter also referred to as a second polymer) and various additives within the limits that achieve the effects described in the present invention. Good too.

When the liquid crystal aligning agent of the present invention contains the second polymer, the ratio of the specific polymer to the total polymer component is preferably 5% by mass or more, and an example thereof is 5 to 95% by mass.

Examples of the second polymer include polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or its derivative, poly(styrene-phenylmaleimide) derivative, poly(meth) Examples include acrylate.

In particular, a polyamic acid obtained from a tetracarboxylic dianhydride component and a diamine component (hereinafter also referred to as second polyamic acid) is preferable as the second polymer.

Examples of the tetracarboxylic dianhydride component for obtaining the second polyamic acid include a compound represented by the following formula (11). The acid dianhydride component may be composed of one type of compound, or may be composed of two or more types of compounds.

In formula (11), A is a tetravalent organic group, preferably a tetravalent organic group having 4 to 30 carbon atoms.

Specific examples of A include the same structures as those exemplified for X ₁ in formula (6), including preferred examples.

The diamine component for obtaining the second polyamic acid can be appropriately determined depending on the purpose, and for example, a diamine represented by the following formula (12) can be used.

(Y ₉ represents a divalent organic group. A ₉ is each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. (They may be the same or different. From the viewpoint of liquid crystal orientation, _A9 is preferably a hydrogen atom or a methyl group.)

The structure of _Y9 in formula (12), which is preferably used as a diamine component for obtaining the second polyamic acid, is shown below, but the present invention is not limited thereto.

For the purpose of improving electrical properties and relaxation properties, _Y9 is a divalent organic group having a secondary or tertiary nitrogen atom, or a divalent organic group having -NH-CO-NH- in the molecule. It is preferable. Specific examples of formula (12) in the case where Y ₉ is a divalent organic group having a secondary or tertiary nitrogen atom include diamines having a pyrrole structure described in International Publication WO2017/126627, preferably A diamine having a structure represented by the following formula (pr);

(R ¹ represents a hydrogen atom, a fluorine atom, a cyano group, a hydroxyl group, or a methyl group, each R ² independently represents a single bond or a group "*1-R ³ -Ph-*2", and R ³ represents a A divalent organic group selected from a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) _l -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO- (l, m represent integers from 1 to 5), *1 represents the site that binds to the benzene ring in formula (pr), *2 represents the site that binds to the amino group in formula (pr) Ph represents a phenylene group. n represents 1 to 3), a diamine having a pyrrole structure described in International Publication WO2018/062197, preferably a diamine having a structure represented by the following formula (pn);

(R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents a single bond or a group "*1-R ⁴ -Ph-*2", R ⁴ represents a single bond, -O-, Represents a divalent organic group selected from -COO-, -OCO-, -(CH ₂ ) _l -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO- (l and m are 1 (represents an integer of ~5), *1 represents a site that binds to the benzene ring in formula (pn), *2 represents a site that binds to an amino group in formula (pn), Ph represents a phenylene group n represents 1 to 3), a diamine having a carbazole structure described in International Publication WO2018/110354, preferably a diamine having a structure represented by the following formula (cz);

(R ¹ represents a hydrogen atom or a methyl group, and R ² represents a methyl group), diamines having nitrogen-containing heterocycles described in paragraphs [0173] to [0188] of International Publication WO2015/046374, and JP A diamine having a nitrogen-containing structure described in paragraph [0050] of Publication No. 2016-218149, a diamine represented by the following formula (BP);

(X is a biphenyl skeleton or a fluorene ring, Y is a benzene ring, a biphenyl skeleton, or a group selected from -Ph-Z-Ph- (Ph represents a phenylene group), and Z is -O-, - It is a divalent group represented by NH-, -CH ₂ -, -SO ₂ -, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -. A and B are hydrogen atoms or methyl groups. ), 2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 5,6-diamino-2,3-dicyanopyrazine, 5,6-diamino -2,4-dihydroxypyrimidine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 1,4-bis(3-aminopropyl)piperazine, 4,4'-[4,4' -propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1 , 3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4-diamino-1 , 3,5-triazine, 4,6-diamino-2-vinyl-1,3,5-triazine, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate , 3,8-diamino-6-phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis(4-aminophenyl)-N-phenylamine, 4,4'-diaminodiphenyl-N -Methylamine, 4,4'-diaminodiphenylamine, 3,6-diaminocarbazole, 9-methyl-3,6-diaminocarbazole, 9-ethyl-3,6-diaminocarbazole, the following formulas (w1) to (w2) Examples include diamines represented by:

(Sp is phenylene, pyrrolidine, piperidine, piperazine, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or -CH ₂ - of the divalent chain hydrocarbon group is -O-, -CO -, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group) represents a group substituted with a group selected from ), -COS-, -NR- (R represents a methyl group), pyrrolidine, piperidine, and piperazine.)

A specific example of the above formula (12) when Y ₉ is a divalent organic group having -NH-CO-NH- in the molecule is the following formula (4), where A ₁ is -NH-CO- NH-, or a group in which at least one -CH ₂ - of an alkylene group having 2 to 20 carbon atoms is substituted with -NH-CO-NH-, or -CH ₂ - of an alkylene group having 2 to 20 carbon atoms at least one of -NH-CO-NH- is substituted with -NH-CO-NH-, and at least one of the other -CH ₂ - is -O-, -CO-, -CO-O-, -NRCO- (R is a hydrogen atom or ), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR- (R represents a methyl group) Examples include diamines which are substituted with a group selected from the group (representing a group). Specific examples of more preferable diamines include diamines represented by the following formulas (U-1) to (U-9).

(A ₁ is a single bond, -NH-CO-NH-, or an alkylene group having 2 to 20 carbon atoms (however, any -CH ₂ - of the alkylene group is -O-, -CO-, -CO- O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group) , -COS-, -NR- (R represents a methyl group) or -NH-CO-NH-). A ₂ is a halogen atom, a hydroxy group, or a carbon number of 1 ~5 represents an alkyl group or alkoxy group (however, any hydrogen atom of the alkyl group or alkoxy group may be substituted with a halogen atom). a is an integer from 0 to 4, and a is an integer of 0 to 4; In the case of 2 or more, A ₂ may be the same or different. b and c are each independently an integer of 1 to 2.)

Preferred specific examples of the diamines represented by the above formulas (w1) to (w2) include diamines represented by the following formulas (n3-1) to (n3-7), and diamines represented by the following formulas (n4-1) to (n4 Examples include diamines represented by -6).

For the purpose of improving printability, a diamine compound having a carboxyl group (COOH group) or a hydroxyl group (OH group) can also be used. Specifically, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 2,4-diaminobenzoic acid, Mention may be made of 2,5-diaminobenzoic acid or 3,5-diaminobenzoic acid. Among these, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, or 3,5-diaminobenzoic acid is preferred. Further, diamine compounds represented by the following formulas [3b-1] to [3b-4] and diamine compounds whose amino groups are secondary amino groups can also be used.

(In formula [3b-1], Q ¹ is a single bond, -CH ₂ -, -C ₂ H ₄ -, -C(CH ₃ ) ₂ -, -CF ₂ -, -C(CF ₃ ) ₂ -, -O-, -CO-, -NH-, -N(CH ₃ )-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -CON( CH ₃ )- or -N(CH ₃ )CO-, m ¹ and m ² each independently represent an integer of 0 to 4, and m ¹ +m ² represents an integer of 1 to 4, and the formula In [3b-2], m ³ and m ⁴ each independently represent an integer of 1 to 5, and in formula [3b-3], Q ² represents a straight chain or branched alkylene group having 1 to 5 carbon atoms. m ⁵ represents an integer from 1 to 5, and in formula [3b-4], Q ³ and Q ⁴ each independently represent a single bond, -CH ₂ -, -C ₂ H ₄ -, -C( CH ₃ ) ₂ -, -CF ₂ -, -C(CF ₃ ) ₂ -, -O-, -CO-, -NH-, -N(CH ₃ )-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -CON(CH ₃ )- or -N(CH ₃ )CO-, m ⁶ is an integer from 1 to 4.)

As the diamine component for obtaining the second polyamic acid, in addition to the above, diamines used in specific polymers and known diamines can be used, but the present invention is not limited thereto. The diamine component for obtaining the second polyamic acid may be one type of diamine, or two or more types of diamine may be used in combination.

<Production method of polyamic acid, polyamic acid ester and polyimide>
The polyamic acid ester, polyamic acid, and polyimide that are the polyimide precursors used in the present invention can be synthesized, for example, by a known method as described in International Publication WO2013/157586.

<Liquid crystal alignment agent>
The liquid crystal aligning agent of the present invention contains a polymer (A). The liquid crystal aligning agent of the present invention may contain other polymers in addition to the polymer (A) and optionally the second polymer. Other types of polymers include polyamic acids, polyimides, polyamic acid esters, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth) ) acrylate, etc.

The liquid crystal alignment agent is used for producing a liquid crystal alignment film, and from the viewpoint of forming a uniform thin film, it is preferable to take the form of a coating liquid. Also in the liquid crystal aligning agent of the present invention, it is preferable that the coating liquid contains the above-described polymer component and an organic solvent. At that time, the concentration of the polymer in the liquid crystal aligning agent can be changed as appropriate depending on the thickness of the coating film to be formed. From the viewpoint of forming a uniform and defect-free coating film, the content is preferably 1% by mass or more, and from the viewpoint of storage stability of the solution, the content is preferably 10% by mass or less. Particularly preferred polymer concentrations are 2 to 8% by weight.

The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as it can uniformly dissolve the polymer component. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, 1,3-dimethyl -2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide (these are also collectively referred to as "good solvents") ), etc. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide or γ-butyrolactone can be used. preferable. The good solvent in the liquid crystal aligning agent of the present invention is preferably 20 to 99% by mass, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass of the total solvent contained in the liquid crystal aligning agent. It is.

In addition to the above-mentioned solvents, the organic solvent contained in the liquid crystal aligning agent may be used in combination with a solvent (also called a poor solvent) that improves the coating properties and surface smoothness of the coating film when applying the liquid crystal aligning agent. It is preferable to use a mixed solvent of Specific examples of organic solvents used in combination are listed below, but the invention is not limited to these examples.
For example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether , 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene Glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2- Propanol, 2-(2-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monomethyl ether Acetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene acetate Glycol monoethyl ether, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol mono Examples include ethyl ether and diisobutyl ketone (2,6-dimethyl-4-heptanone).

Among them, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene Preferably, glycol monobutyl ether acetate and diisobutyl ketone are used.

Preferred solvent combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, and N-methyl-2-pyrrolidone and γ-butyrolactone and ethylene glycol monobutyl ether. Pyrrolidone and γ-butyrolactone and 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 and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N -Methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanol, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol dimethyl ether. These poor solvents preferably account for 1 to 80% by mass, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass of the total solvent contained in the liquid crystal aligning agent. The type and content of such a solvent are appropriately selected depending on the liquid crystal aligning agent coating device, 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. Such additional components include adhesion aids to improve the adhesion between the liquid crystal alignment film and the substrate and the adhesion between the liquid crystal alignment film and the sealing material, and compounds (hereinafter referred to as crosslinking agents) to increase the strength of the liquid crystal alignment film. ), dielectric materials and conductive materials for adjusting the dielectric constant and electrical resistance of the liquid crystal alignment film.

The crosslinkable compound includes an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, and a Meldrum acid structure, from the viewpoint of less generation of AC afterimages and a high effect of improving film strength. A compound having at least one group selected from the group consisting of a cyclocarbonate group, a cyclocarbonate group, and a group represented by the following formula (d), or a compound selected from a compound represented by the following formula (e) (hereinafter referred to as are also collectively referred to as compound (C)) are preferred.

(In the formula, R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ --OH", and R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or It is an alkyl group or "*-CH ₂ -OH". * indicates a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer from 1 to 6, n represents an integer from 0 to 4.)

Specific examples of compounds having an oxiranyl group include compounds described in paragraph [0037] of JP-A-10-338880 and compounds having a triazine ring as a skeleton described in International Publication No. WO2017/170483. , compounds having two or more oxiranyl groups. Among these, N,N,N',N'-tetraglycidyl-m-xylene diamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetra Nitrogen atoms such as glycidyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, compounds represented by the following formulas (r-1) to (r-3), etc. Compounds containing are particularly preferred.

Specific examples of compounds having oxetanyl groups include, for example, compounds having two or more oxetanyl groups described in paragraphs [0170] to [0175] of International Publication No. 2011/132751.

Specific examples of compounds having a protected isocyanate group include, for example, compounds having two or more protected isocyanate groups described in paragraphs [0046] to [0047] of JP-A No. 2014-224978, and International Publication No. 2015/141598. Examples include compounds having three or more protected isocyanate groups as described in paragraphs [0119] to [0120] of the above issue. Among these, compounds represented by the following formulas (bi-1) to (bi-3) are preferred.

Specific examples of compounds having a protected isothiocyanate group include, for example, compounds having two or more protected isothiocyanate groups described in JP-A-2016-200798.

Specific examples of compounds having a group containing an oxazoline ring structure include, for example, compounds containing two or more oxazoline structures described in paragraph [0115] of JP-A No. 2007-286597.

Specific examples of compounds having a group containing a Meldrum's acid structure include compounds having two or more Meldrum's acid structures described in International Publication No. WO2012/091088.

Specific examples of compounds having a cyclocarbonate group include, for example, the compounds described in International Publication No. WO2011/155577.

Examples of the alkyl group having 1 to 3 carbon atoms for R ₇₁ , R ₇₂ , and R ₇₃ in the group represented by formula (d) include a methyl group, an ethyl group, and a propyl group.

Specific examples of compounds having the group represented by the formula (d) include the compound having the formula (d) described in International Publication No. WO2015/072554 and paragraph [0058] of JP2016-118753. ), compounds described in JP-A No. 2016-200798, and the like. Among these, compounds represented by the following formulas (hd-1) to (hd-8) are preferred.

The (m+n)-valent organic group having an aromatic ring in A of the formula (e) includes an (m+n)-valent aromatic hydrocarbon group having 5 to 30 carbon atoms, and an aromatic hydrocarbon group having 5 to 30 carbon atoms. Examples include (m+n)-valent organic groups to which are bonded directly or via a linking group, and (m+n)-valent groups having an aromatic heterocycle. Examples of the aromatic hydrocarbon group include benzene and naphthalene. Examples of aromatic heterocycles include pyrrole ring, imidazole ring, pyrazole ring, pyridine ring, pyrimidine ring, quinoline ring, isoquinoline ring, carbazole ring, pyridazine ring, pyrazine ring, benzimidazole ring, benzimidazole ring, indole ring, and quinoxaline. ring, acridine ring, etc. Examples of the linking group include an alkylene group having 1 to 10 carbon atoms, a group obtained by removing one hydrogen atom from the alkylene group, and a divalent or trivalent cyclohexane ring. Note that any hydrogen atom of the alkylene group may be substituted with a fluorine atom or an organic group such as a trifluoromethyl group. Specific examples include compounds described in International Publication No. WO2010/074269. Preferred specific examples include the following formulas (e-1) to (e-9).

The above compounds are examples of crosslinkable compounds, and the present invention is not limited thereto. For example, components other than the above disclosed on pages 53 [0105] to 55 [0116] of International Publication No. 2015/060357 may be mentioned. Moreover, the number of the crosslinkable compounds contained in the liquid crystal aligning agent of this invention may be one type, and may combine two or more types.
The content of the crosslinkable compound in the liquid crystal aligning agent of the present invention is preferably 0.5 to 20 parts by mass based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent, so that the crosslinking reaction proceeds. The amount is more preferably 1 to 15 parts by mass from the viewpoint of achieving the desired effect and minimizing the occurrence of AC afterimages.

Examples of the adhesion aid include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N -(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N -Ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl -1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diaza Nonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane , N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4- Epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p - Styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxy Examples include silane coupling agents such as silane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane. When using these silane coupling agents, the amount is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 30 parts by mass based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent, from the viewpoint of reducing generation of AC afterimages. is 0.1 to 20 parts by mass.

<Liquid crystal alignment film/liquid crystal display element>
A liquid crystal aligning film can be manufactured by using the above-mentioned liquid crystal aligning agent. Moreover, the liquid crystal display element based on this invention comprises the liquid crystal alignment film formed using the said liquid crystal alignment agent. The operation mode of the liquid crystal display element according to the present invention is not particularly limited, and may be, for example, a TN (Twisted Nematic) type, an STN type, a vertical alignment type (including VA-MVA type, VA-PVA type, etc.), or an in-plane switching type. The present invention can be applied to various operation modes such as (IPS type), FFS (Fringe Field Switching) type, and optical compensation bend type (OCB type).

The liquid crystal display element according to the present invention can be manufactured, for example, by a process including the following steps (1-1) to (1-3). In step (1-1), the substrate used differs depending on the desired operation mode. Step (1-2) and step (1-3) are common to each operation mode.

[Step (1-1): Formation of coating film]
First, the liquid crystal aligning agent of the present invention is applied onto a substrate, and then the applied surface is heated to form a coating film on the substrate.

(1-1A)
For example, when manufacturing a TN-type, STN-type, or VA-type liquid crystal display element, first, a pair of two substrates each having a patterned transparent conductive film are formed, and the above-mentioned The liquid crystal aligning agent prepared above is preferably applied by an offset printing method, a spin coating method, a roll coater method, or an inkjet printing method. As the substrate, for example, a transparent substrate made of glass such as float glass or soda glass; or plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, or poly(alicyclic olefin) can be used. The transparent conductive film provided on one surface of the substrate includes a NESA film (registered trademark of PPG, Inc., USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), etc. Can be used. To obtain a patterned transparent conductive film, for example, a method of forming a patternless transparent conductive film and then forming a pattern by photo-etching; a method of using a mask having a desired pattern when forming the transparent conductive film; etc. When applying the liquid crystal aligning agent, a functional silane compound or a functional titanium compound is added to the surface of the substrate where the coating film will be formed, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film. It is also possible to perform a pre-treatment such as coating in advance.

After applying the liquid crystal aligning agent, preheating (prebaking) is preferably performed for the purpose of preventing the applied liquid crystal aligning agent from dripping. The prebaking temperature is preferably 30 to 200°C, more preferably 40 to 150°C, particularly preferably 40 to 100°C. Prebaking time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Thereafter, a calcination (post-bake) step is performed for the purpose of completely removing the solvent and, if necessary, thermally imidizing the amic acid structure present in the polymer. The firing temperature (post-bake temperature) at this time is preferably 80 to 300°C, more preferably 120 to 250°C. The post-bake time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The thickness of the film thus formed is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.

(1-1B)
When manufacturing an IPS type or FFS type liquid crystal display element, the electrode forming surface of the substrate is provided with electrodes made of a transparent conductive film or metal film patterned in a comb-tooth shape, and the counter substrate is not provided with electrodes. A coating film is formed by applying a liquid crystal aligning agent to one surface of the substrate and then heating each coating surface. The materials of the substrate and transparent conductive film used at this time, the coating method, the heating conditions after coating, the patterning method of the transparent conductive film or metal film, the pretreatment of the substrate, and the preferred thickness of the coating film to be formed are described above. This is the same as (1-1A). As the metal film, for example, a film made of metal such as chromium can be used.

In both cases of (1-1A) and (1-1B) above, a liquid crystal aligning film or a coating film that becomes a liquid crystal aligning film is formed by applying a liquid crystal aligning agent on the substrate and then removing the organic solvent. Ru. At this time, by further heating after the coating film is formed, the dehydration ring-closing reaction of the polyamic acid, polyamic acid ester, and polyimide blended in the liquid crystal aligning agent according to the present invention may proceed, resulting in a more imidized coating film. .

[Step (1-2): Orientation ability imparting treatment]
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal display element, a treatment is performed to impart liquid crystal alignment ability to the coating film formed in the above step (1-1). Thereby, the ability to orient liquid crystal molecules is imparted to the coating film, and it becomes a liquid crystal alignment film. Treatments to impart alignment ability include, for example, rubbing treatment in which the paint film is rubbed in a certain direction with a roll wrapped with cloth made of fibers such as nylon, rayon, or cotton, and photo-alignment treatment in which the paint film is irradiated with polarized or non-polarized radiation. Examples include processing. On the other hand, when manufacturing a VA type liquid crystal display element, the coating film formed in step (1-1) above can be used as it is as a liquid crystal alignment film, but the coating film may be subjected to an alignment ability imparting treatment. You can.

When imparting liquid crystal alignment ability to a coating film by photoalignment treatment, the radiation irradiated to the coating film can be, for example, ultraviolet rays and visible light containing light with a wavelength of 150 to 800 nm. If the radiation is polarized, it may be linearly polarized or partially polarized. Further, when the radiation used is linearly polarized light or partially polarized light, irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these may be performed. When irradiating non-polarized radiation, the direction of irradiation is oblique.

Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, excimer lasers, and the like. Ultraviolet light in a preferred wavelength range can be obtained by using a light source in conjunction with, for example, a filter, a diffraction grating, or the like. The radiation dose is preferably 10 to 5,000 mJ/cm ² , more preferably 30 to 2,000 mJ/cm ² .

Furthermore, the coating film may be irradiated with light while the coating film is being heated in order to increase the reactivity. The temperature during heating is usually 30 to 250°C, preferably 40 to 200°C, more preferably 50 to 150°C.

In addition, when using ultraviolet rays containing light with a wavelength of 150 to 800 nm, the light irradiation film obtained in the above process can be used as a liquid crystal alignment film as it is, but the light irradiation film may be heated, Washing with organic solvents or a combination thereof may also be performed. The firing temperature at this time is preferably 80 to 300°C, more preferably 80 to 250°C. The firing time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. Note that the firing may be performed once or twice or more. The photo-alignment treatment here corresponds to the treatment of light irradiation in a state where the liquid crystal layer is not in contact with the liquid crystal layer.

The organic solvent used for the above washing is not particularly limited, but specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy- Examples include 2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate.

In addition, the liquid crystal alignment film after the rubbing treatment may be further processed by irradiating a part of the liquid crystal alignment film with ultraviolet rays to change the pretilt angle of a part of the liquid crystal alignment film, or by changing a part of the surface of the liquid crystal alignment film. After forming a resist film on the area, a rubbing process may be performed in a direction different from the previous rubbing process, and then the resist film may be removed, so that the liquid crystal alignment film has a different liquid crystal alignment ability for each area. . In this case, it is possible to improve the visibility characteristics of the resulting liquid crystal display element. A liquid crystal alignment film suitable for a VA type liquid crystal display element can also be suitably used for a PSA (Polymer Sustained Alignment) type liquid crystal display element.

[Step (1-3): Construction of liquid crystal cell]
(1-3A)
A liquid crystal cell is manufactured by preparing two substrates on which liquid crystal alignment films are formed as described above, and disposing a liquid crystal between the two substrates that are arranged facing each other. For example, the following two methods can be used to manufacture a liquid crystal cell. The first method is a conventionally known method. First, two substrates are placed facing each other with a gap (cell gap) in between so that the respective liquid crystal alignment films face each other, and the peripheral parts of the two substrates are pasted together with a sealant, and the substrate surface and the sealant are used to divide the two substrates. A liquid crystal cell is manufactured by injecting liquid crystal into the cell gap and sealing the injection hole. The second method is a technique called ODF (One Drop Fill) method. For example, an ultraviolet light curing sealant is applied to a predetermined location on one of the two substrates on which a liquid crystal alignment film has been formed, and liquid crystal is then dropped at several predetermined locations on the surface of the liquid crystal alignment film. After that, the other substrate is attached so that the liquid crystal alignment films are facing each other, and the liquid crystal is spread over the entire surface of the substrate. Then, the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby producing a liquid crystal cell. . Regardless of the method used, the liquid crystal cell manufactured as described above is further heated to a temperature at which the liquid crystal used takes an isotropic phase, and then slowly cooled to room temperature to improve the flow orientation during filling of the liquid crystal. It is desirable to remove it.

As the sealant, for example, an epoxy resin containing a hardening agent and aluminum oxide spheres as spacers can be used.

Examples of liquid crystals include nematic liquid crystals and smectic liquid crystals, and among them, nematic liquid crystals are preferred, such as Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, and biphenyl liquid crystals. Cyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, cuban-based liquid crystals, etc. can be used. Furthermore, in addition to these liquid crystals, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate, and cholesteryl carbonate; chiral agents such as those sold under the trade names "C-15" and "CB-15" (manufactured by Merck &Co.); Ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be added and used. The liquid crystal can also additionally contain an anisotropic dye. The term "dye" can mean a substance capable of intensively absorbing or transforming light in the visible light range, for example in the 400 nm to 700 nm wavelength range, at least in part or in its entirety; The term "isotropic dye" may refer to a substance capable of anisotropic absorption of light in at least a portion or the entire visible light region.
The color sense of the liquid crystal cell can be controlled through the use of dyes as described above. The type of anisotropic dye is not particularly limited, and for example, black dye or color dye may be used. The ratio of the anisotropic dye to the liquid crystal is appropriately selected within a range that does not impair the desired physical properties. For example, the ratio of the anisotropic dye to 100 parts by weight of the liquid crystal compound is 0.01 to 5 parts by weight. However, the above ratio can be changed to an appropriate range as necessary.

(1-3B)
When manufacturing a PSA type liquid crystal display element, the process is the same as the above (1-3A) except that photopolymerizable compounds such as the following formulas (w-1) to (w-5) are injected or dropped together with the liquid crystal. to construct a liquid crystal cell.

Thereafter, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates. The voltage applied here can be, for example, 5 to 50 V direct current or alternating current. Further, as the light to be irradiated, for example, ultraviolet rays and visible light including light with a wavelength of 150 to 800 nm can be used, but ultraviolet rays including light with a wavelength of 300 to 400 nm are preferable. As a light source for the irradiation light, for example, a low pressure mercury lamp, a high pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, etc. can be used. Note that the ultraviolet rays in the above preferred wavelength range can be obtained by using a light source in combination with, for example, a filter diffraction grating. The amount of light irradiation is preferably 100 mJ/cm ² or more and less than 30,000 mJ/cm ² , more preferably 100 to 20,000 mJ/cm ² .

(1-3C)
When a coating film is formed on a substrate using a liquid crystal aligning agent containing a compound (polymer or additive) having a photopolymerizable group, a liquid crystal cell is constructed in the same manner as in (1-3A) above, and then, A method may be adopted in which a liquid crystal display element is manufactured by passing through a step of irradiating a liquid crystal cell with light while applying a voltage between conductive films of a pair of substrates. According to this method, the advantages of the PSA mode can be realized with a small amount of light irradiation. The liquid crystal cell may be irradiated with light while the liquid crystal is being driven by voltage application, or may be irradiated with a voltage that is low enough not to drive the liquid crystal. The applied voltage can be, for example, 0.1 to 30V direct current or alternating current. Regarding the conditions of the irradiation light, the explanation in (1-3B) above can be applied. The light irradiation treatment here corresponds to light irradiation treatment in a state in which the liquid crystal layer is in contact.

Then, by bonding a polarizing plate to the outer surface of the liquid crystal cell, a liquid crystal display element according to the present invention can be obtained. The polarizing plate bonded to the outer surface of the liquid crystal cell is a polarizing plate in which a polarizing film called "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine is sandwiched between cellulose acetate protective films, or the H film itself. For example, a polarizing plate consisting of:

The liquid crystal display element according to the present invention can be effectively applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, and smartphones. It can be used in various display devices such as various monitors, liquid crystal televisions, and information displays.

As described above, by using the liquid crystal aligning agent of the present invention, there is provided a liquid crystal aligning film that has less generation of afterimages and can minimize bright spots even when physical friction such as rubbing by a spacer occurs, and a liquid crystal aligning film equipped with the same. A liquid crystal display element can be obtained. Moreover, the obtained liquid crystal display element has high reliability.

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not to be construed as being limited thereto. The abbreviations of the compounds used are as follows.
(liquid crystal)
MLC-3019 (manufactured by Merck & Co., positive type liquid crystal)
(Diamine compound)
WA-1: Compound represented by formula [WA-1] WA-2: Compound represented by formula [WA-2]

(Other diamine compounds)
A1 to A7: Compounds represented by formula [A1] to formula [A7], respectively

(Boc represents a tert-butoxycarbonyl group.)

(Acid dianhydride compound)
B1 to B3: Compounds represented by formula [B1] to formula [B3], respectively

(solvent)
NMP: N-methyl-2-pyrrolidone BCS: Ethylene glycol monobutyl ether GBL: γ-butyllactone (additive)
S-1: 3-glycidoxypropyltriethoxysilane (crosslinking agent)
AD-1: Compound represented by the following formula (AD-1)

(molecular weight measurement)
The molecular weights of the polyimide precursor and polyimide were determined as follows using a room temperature gel permeation chromatography (GPC) device (GPC-101) (manufactured by Showa Denko) and columns (KD-803, KD-805) (manufactured by Shodex). It was measured as follows.
Column temperature: 50℃
Eluent: N,N-dimethylformamide (as additives, lithium bromide monohydrate (LiBr.H ₂ O) is 30 mmol/L (liter), phosphoric acid/anhydrous crystal (o-phosphoric acid) is 30 mmol/ L, tetrahydrofuran (THF) 10 mL/L)
Flow rate: 1.0 mL/min Standard sample for creating a calibration curve: TSK standard polyethylene oxide (molecular weight: approx. 900,000, 150,000, 100,000 and 30,000) (manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight: approx. 12,000, 4,000 and 1,000) (manufactured by Polymer Laboratory).

(Measurement of imidization rate of polyimide)
Put 20 mg of polyimide powder into an NMR (nuclear magnetic resonance) sample tube (NMR sampling tube standard, φ5 (manufactured by Kusano Kagaku)) and add deuterated dimethyl sulfoxide (DMSO-d6, 0.05% by mass TMS (tetramethylsilane)). Mixed product) (0.53 mL) was added and completely dissolved by applying ultrasound. This solution was subjected to proton NMR measurement at 500 MHz using an NMR measuring device (JNW-ECA500) (manufactured by JEOL Datum). The imidization rate is determined using a proton derived from a structure that does not change before and after imidization as a reference proton, and the peak integrated value of this proton and the proton peak derived from the NH group of amic acid that appears around 9.5 to 10.0 ppm. It was calculated using the following formula using the integrated value.
Imidization rate (%) = (1-α・x/y)×100
In the above formula, x is the integrated value of the proton peak derived from the NH group of amic acid, y is the integrated peak value of the standard proton, and α is one NH group proton of the amic acid in the case of polyamic acid (imidization rate is 0%). This is the ratio of the number of standard protons to the standard proton.

(Viscosity measurement)
In the synthesis examples or comparative synthesis examples, the viscosity of the polyimide polymer was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL and a cone rotor TE-1 (1° 34', R24), measured at a temperature of 25°C.

(WA-1) was synthesized with reference to the following prior literature.
Salvatore Zarra, Jack K. Clegg, Jonathan R. Nitschke, Angewandte Chemie International Edition, 52, 18, (4837-4840, Supporting Information:S2-S3), (2013).

(WA-2) is a new compound that has not been published in the literature, and the synthesis method will be described in detail below.

The product described in Synthesis Example 1 below was identified by ¹ H-NMR analysis (analysis conditions are as follows).
Equipment: BRUKER ADVANCE III-500MHz
Measurement solvent: DMSO- _d6
Reference substance: Tetramethylsilane (TMS) (δ0.0 ppm for ¹ H)

The abbreviations used in the present invention have the following meanings.
THF: Tetrahydrofuran DCE: 1,2-dichloroethane DMAP: N,N-dimethyl-4-aminopyridine

<<Monomer Synthesis Example 1 Synthesis of WA-2>>

<Synthesis of compound [1]>
In 1,2-dichloroethane (540 g), (4,4'-dinitro-[1,1'-biphenyl]-2,2'-diyl)dimethanol (60.0 g, 0.197 mol), triethylamine (45. 9 g, 0.454 mol) and N,N-dimethyl-4-aminopyridine (2.39 g, 0.0197 mol) were added and stirred under ice-cooling conditions. Di-tert-butyl dicarbonate (94.7 g, 0.434 mol) diluted with 1,2-dichloroethane (60 g) was added dropwise while being careful to avoid heat generation, and when the heat generation stopped, the mixture was stirred overnight at room temperature. After the reaction was completed, stirring was stopped, and water (600 g) was added to separate and wash the mixture, followed by liquid separation and extraction with chloroform (300 g x 2). The organic phase was concentrated, and the obtained crude product was purified by silica gel column chromatography using a mixed solvent of ethyl acetate/hexane = 2/1 (volume ratio). The obtained solution was concentrated and dried, and the compound [1 ] was obtained (yield: 102 g). The obtained compound was used as it was in the next step.
^1H -NMR (500MHz) in DMSO- _d6 : 8.41ppm (s, 2H), 8.33ppm (d, 2H, J = 8.5Hz), 7.58ppm (d, 2H, J = 8.5Hz ), 4.90ppm (s, 4H), 1.39ppm (s, 18H).

<Synthesis of WA-2>
In tetrahydrofuran (600 g), compound [1] crude material (101 g) and 3% platinum carbon (water-containing product) (8.00 g) were charged, and the mixture was stirred under hydrogen atmosphere at room temperature overnight. After the reaction was completed, platinum carbon was removed by filtration and concentrated under reduced pressure. Methanol was added to the crude product and it was concentrated again and dried to obtain WA-2 (yield: 86.6 g, 0.195 mol).
^1H -NMR (500MHz) in DMSO- _d6 : 6.72ppm (d, 2H, J = 8.0Hz), 6.63ppm (d, 2H, J = 2.5Hz), 6.52ppm (d, 1H , J = 2.5Hz), 6.50ppm (d, 1H, J = 2.0Hz), 5.15ppm (s, 4H), 4.64-4.59ppm (m, 4H), 1.34ppm (s , 18H).

(Synthesis example 1)
WA-1 (2.19g, 9.00mmol), A1 (1.83g, 7.50mmol), A2 (1.72g, 7.50mmol), A4 (2.04g, 6.00mmol) and B2 (1. 12g, 4.50mmol) in NMP (50.6g) and reacted at 50°C for 3 hours, then added B1 (5.32g, 23.7mmol) and NMP (30.1g), The reaction was carried out at ℃ for 15 hours to obtain a polyamic acid solution [1] with a resin solid content concentration of 15% by mass (viscosity: 384 mPa·s).
After adding NMP to the obtained polyamic acid solution [1] (30.0 g) and diluting it to 10.0% by mass, acetic anhydride (4.83 g) and pyridine (1.50 g) were added as an imidization catalyst, The reaction was carried out at 55°C for 2.5 hours. This reaction solution was poured into methanol (280 mL), and the resulting precipitate was filtered off. This precipitate was washed with methanol and dried under reduced pressure at 100°C to obtain polyimide powder (1). The imidization rate of this polyimide was 78.1%, the number average molecular weight was 12,322, and the weight average molecular weight was 44,438.

(Synthesis example 2)
WA-2 (4.00 g, 9.00 mmol), A1 (1.83 g, 7.50 mmol), A2 (1.72 g, 7.50 mmol), A4 (2.04 g, 6.00 mmol) and B2 (1. 12g, 4.50mmol) in NMP (50.6g) and reacted at 50°C for 3 hours, then added B1 (5.32g, 23.7mmol) and NMP (30.1g), The reaction was carried out at ℃ for 15 hours to obtain a polyamic acid solution [2] with a resin solid content concentration of 15% by mass (viscosity: 188 mPa·s).
After adding NMP to the obtained polyamic acid solution [2] (30.0 g) and diluting it to 10.0% by mass, acetic anhydride (4.83 g) and pyridine (1.50 g) were added as an imidization catalyst, The reaction was carried out at 55°C for 2.5 hours. This reaction solution was poured into methanol (280 mL), and the resulting precipitate was filtered off. This precipitate was washed with methanol and dried under reduced pressure at 100°C to obtain polyimide powder (2). The imidization rate of this polyimide was 80.1%, the number average molecular weight was 10,582, and the weight average molecular weight was 41,856.

(Synthesis example 3)
A6 (1.19g, 6.00mmol), A7 (4.78g, 24.0mmol) and B2 (3.75g, 15.0mmol) were mixed in NMP (55.1g) and reacted at 50°C for 3 hours. After that, B3 (4.06 g, 13.8 mmol) and NMP (23.0 g) were added and reacted at 70°C for 15 hours to form a polyamic acid solution [3] with a resin solid concentration of 15% by mass (viscosity 941 mPa).・s) was obtained.
The number average molecular weight of the polyamic acid solution [3] was 15,244, and the weight average molecular weight was 40,724.

(Comparative synthesis example 1)
A5 (1.91 g, 9.00 mmol), A1 (1.83 g, 7.50 mmol), A2 (1.72 g, 7.50 mmol), A4 (2.04 g, 6.00 mmol) and B2 (1.12 g, After mixing 4.50 mmol) in NMP (50.6 g) and reacting at 50°C for 3 hours, B1 (5.32 g, 23.7 mmol) and NMP (30.1 g) were added, and the mixture was reacted at 40°C. The reaction was carried out for 15 hours to obtain a polyamic acid solution [R1] (viscosity: 365 mPa·s) with a resin solid content concentration of 15% by mass.
After adding NMP to the obtained polyamic acid solution [R1] (30.0 g) and diluting it to 10.0% by mass, acetic anhydride (4.83 g) and pyridine (1.50 g) were added as an imidization catalyst, The reaction was carried out at 55°C for 2.5 hours. This reaction solution was poured into methanol (280 mL), and the resulting precipitate was filtered off. This precipitate was washed with methanol and dried under reduced pressure at 100°C to obtain polyimide powder (R1). The imidization rate of this polyimide was 76.1%, the number average molecular weight was 10,958, and the weight average molecular weight was 39,958.

<Preparation of liquid crystal alignment agent>
In Examples and Comparative Examples, preparation examples of liquid crystal aligning agents are described. Using the liquid crystal alignment agents obtained in Examples and Comparative Examples, liquid crystal display elements were manufactured and various evaluations were performed.

(Example 1)
NMP (22.0 g) was added to the polyimide powder (1) (3.00 g) obtained in Synthesis Example 1, and dissolved by stirring at 80° C. for 15 hours. To this solution (2.75 g), the polyamic acid solution [3] obtained in Synthesis Example 3 (3.30 g), NMP (1.35 g), GBL (3.675 g), BCS (3.00 g), AD -1 NMP 10 mass % diluted solution (0.248 g) and S-1 GBL 1 mass % diluted solution (0.825 g) were added and stirred at room temperature for 5 hours to obtain a liquid crystal alignment agent (V-1). . No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that it was a uniform solution.

(Example 2)
A liquid crystal aligning agent (V-2) was obtained in the same manner as in Example 1, except that polyimide powder (2) was used instead of polyimide powder (1). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that it was a uniform solution.

(Comparative example 1)
A liquid crystal aligning agent (W-1) was obtained in the same manner as in Example 1, except that polyimide powder (R1) was used instead of polyimide powder (1). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that it was a uniform solution.

<Preparation of sample for seal adhesion evaluation>
Samples for adhesion evaluation were prepared as follows. On a 30 mm x 40 mm ITO substrate, apply the liquid crystal aligning agents (V-1) and (V-2) obtained in the examples and the liquid crystal aligning agent (W-1) obtained in the comparative example by spin coating. did. After drying on a hot plate at 80° C. for 120 seconds, baking was performed for 20 minutes in a hot air circulation oven at 230° C. to form a coating film with a thickness of 100 nm to obtain a substrate with a liquid crystal alignment film.
Two substrates obtained in this way were prepared, and after applying bead spacers with a diameter of 4 μm on the liquid crystal alignment film surface of one substrate, a sealant (XN-1500T manufactured by Kyoritsu Kagaku Sangyo Co., Ltd.) was dropped. . Next, the other substrate was bonded with the liquid crystal alignment film surface facing inward so that the overlapping width around the substrates was 1 cm each. At that time, the amount of the sealant dropped was adjusted so that the diameter of the sealant after bonding was 3 mm. After fixing the two bonded substrates with clips, they were exposed to 3J of 365 nm light and thermally cured at 120° C. for 1 hour to prepare samples for adhesion evaluation.

<Evaluation of adhesion>
After that, the sample substrate obtained above was fixed at the edge of the upper and lower substrates using a tabletop precision universal testing machine AGS-X500N manufactured by Shimadzu Corporation, and then pushed from the top of the center of the substrate to peel it off. The actual force (N) was measured. A value (N) of less than 3.50 was defined as "bad", and a value of 3.50 or more was defined as "good". The results are shown in Table 1.

<Membrane strength (membrane hardness) evaluation>
A liquid crystal aligning agent was applied by spin coating to the ITO surface of a glass substrate having ITO electrodes on the entire surface. After drying on a hot plate at 80° C. for 2 minutes, a coating film with a thickness of 100 nm was formed. The coating surface was irradiated with polarized ultraviolet rays at a dose of 150 mJ/cm ² to perform orientation treatment. Thereafter, baking was performed at 230° C. for 30 minutes using an IR oven to obtain a substrate with a liquid crystal alignment film. This liquid crystal alignment film was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm/sec, pushing length: 0.6 mm). This substrate was measured using a HZ-V3 haze meter manufactured by Suga Test Instruments. Evaluation was performed by defining a haze value of 0.3 or more as "bad" and a haze value of less than 0.3 as "good." The results are shown in Table 1.

<Preparation of liquid crystal cell for evaluating liquid crystal orientation>
Below, a method for producing a liquid crystal cell for evaluating liquid crystal orientation will be shown.
A liquid crystal cell having the configuration of an FFS type liquid crystal display element was manufactured. First, a substrate with electrodes was prepared. The substrate is a glass substrate measuring 30 mm x 35 mm and having a thickness of 0.7 mm. An IZO electrode constituting a counter electrode was formed over the entire surface of the substrate as a first layer. A SiN (silicon nitride) film formed by a CVD method was formed as a second layer on the first layer of counter electrode. The second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film. On the second layer of SiN film, a comb-shaped pixel electrode formed by patterning an IZO film was arranged as a third layer to form two pixels, a first pixel and a second pixel. . The size of each pixel is approximately 10 mm in length and approximately 5 mm in width. 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 pixel electrode in the third layer is a comb-like structure made by arranging a plurality of dogleg-shaped electrode elements with a bent central part, similar to the figure described in JP-A-2014-77845 (Japanese Patent Publication). It has the shape of The width of each electrode element in the lateral direction is 3 μm, and the interval between electrode elements is 6 μm. The pixel electrode that forms each pixel is constructed by arranging multiple dogleg-shaped electrode elements with a bent central portion, so the shape of each pixel is not rectangular but bent at the central portion like the electrode element. , with a bold, dogleg-like shape. Each pixel is divided into upper and lower parts with the central bent part as a boundary, and has a first area above the bent part and a second area below the bent part.
Comparing the first region and the second region of each pixel, the formation directions of the electrode elements of the pixel electrodes that constitute them are different. That is, in the first region of the pixel, the electrode elements of the pixel electrode are formed so as to form an angle of +80° (clockwise) when the direction of the line segment projected onto the substrate is the polarization plane of polarized ultraviolet light, which will be described later. However, in the second region of the pixel, the electrode elements of the pixel electrode were formed at an angle of −80° (clockwise). That is, in the first region and the second region of each pixel, the direction of rotational movement (in-plane switching) within the substrate plane of the liquid crystal induced by voltage application between the pixel electrode and the counter electrode is as follows. They were arranged in opposite directions.

Next, the liquid crystal aligning agents obtained in the synthesis examples and comparative synthesis examples were filtered through a 1.0 μm filter, and then applied to the prepared electrode-equipped substrate by spin coating. Then, it was dried for 120 seconds on a hot plate set at 80°C. Next, using an exposure apparatus manufactured by Ushio Inc.: APL-L050121S1S-APW01, the substrate was irradiated with linearly polarized ultraviolet light from the vertical direction through a wavelength selection filter and a polarizing plate. At this time, the direction of the polarization plane was set so that the direction of the line segment of the polarization plane of the polarized ultraviolet rays projected onto the substrate was inclined at 80 degrees with respect to the third layer IZO comb-shaped electrode. Next, baking was performed in an IR (infrared) oven at 230° C. for 30 minutes to obtain a substrate with a polyimide liquid crystal alignment film having a thickness of 100 nm and subjected to alignment treatment. Further, as a counter substrate, a glass substrate having a columnar spacer having a height of 4 μm and having an ITO electrode formed on the back surface was also subjected to alignment treatment in the same manner as above to obtain a substrate with a polyimide liquid crystal alignment film. These two substrates with a liquid crystal alignment film are made into a set, and a sealant is printed on one substrate with a liquid crystal injection port left on it. The polarized light planes were pasted together and crimped so that the directions of the line segments projected onto the substrate were parallel to each other. Thereafter, the sealant was cured to produce empty cells with a cell gap of 4 μm. Liquid crystal MLC-3019 (positive liquid crystal manufactured by Merck & Co., Ltd.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS type liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 120° C. for 30 minutes, left at 23° C. overnight, and then used for evaluation of liquid crystal orientation.

<Evaluation of liquid crystal orientation>
Using this liquid crystal cell, those in which flow orientation was confirmed were defined as "bad", and those in which flow orientation was not confirmed were defined as "good". The results are shown in Table 1.

As can be seen from the above results, in the adhesion evaluation, the liquid crystal alignment film obtained from the liquid crystal alignment agent using diamine compounds WA-1 and WA-2 was lower than that obtained from the liquid crystal alignment agent using diamine compound A5. It was found that the adhesion was higher than that of the film. Specifically, this is shown in a comparison between Examples 1 and 2 and Comparative Example 1 shown in Table 1.
Furthermore, in film strength evaluation, liquid crystal alignment films obtained from liquid crystal alignment agents using diamine compounds WA-1 and WA-2 had higher film strength than liquid crystal alignment films obtained from liquid crystal alignment agents using diamine compound A5. I found out that it shows. Specifically, this is shown in a comparison between Examples 1 and 2 and Comparative Example 1 shown in Table 1.
The liquid crystal alignment film obtained from the liquid crystal alignment agent using diamine compounds WA-1 and WA-2 can exhibit liquid crystal alignment properties equivalent to the liquid crystal alignment film obtained from the liquid crystal alignment agent using diamine compound A5. Do you get it.
From the above, using WA-1 and WA-2, which have a biphenyl skeleton and specific side chains, can improve seal adhesion and film strength while maintaining liquid crystal orientation. It becomes possible.

A liquid crystal display element using a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can be suitably used for a liquid crystal display element. These elements are also useful in liquid crystal displays for display purposes, as well as in dimming windows and optical shutters that control transmission and blocking of light.

Claims (6)

A liquid crystal aligning agent containing a polymer obtained from a diamine having a structure represented by the following formula (1).
A is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a benzyl group, a p-methoxybenzyl group, an acetyl group, a benzoyl group, a t-butyloxycarbonyl group, a 9-fluorenylmethoxycarbonyl group, or R ₁ R ₂ R ₃ represents a Si group, and R ₁ , R ₂ and R ₃ each independently represent an alkyl group having 1 to 3 carbon atoms or a phenyl group. The liquid crystal aligning agent according to claim 1, wherein the polymer is at least one selected from a polyimide precursor containing a structural unit represented by the following formula (6) and a polyimide that is an imidized product thereof.
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 formula (1), and R ₄ is a hydrogen atom or a carbon atom having 1 -5 alkyl group. The liquid crystal aligning agent according to claim 2 , wherein in the formula (6), the structure of X ₁ is at least one selected from the following structures.
The liquid crystal aligning agent according to claim 2 or 3 , wherein the structural unit represented by formula (6) is 10 mol% or more based on the total structural units of the polymer. A liquid crystal aligning film obtained using the liquid crystal aligning agent according to any one of claims 1 to 4. A liquid crystal display element comprising the liquid crystal alignment film according to claim 5.