TW201823303A - Liquid crystal aligning agent, liquid crystal alignment film and liquid crystal display element having good afterimage characteristics without producing bright dots even if used for negative liquid crystals - Google Patents

Abstract

Provided are a liquid crystal aligning agent for obtaining an alignment film that is suitable for photo-alignment and enables the achievement of good afterimage characteristics without producing bright dots even if used for negative liquid crystals, a liquid crystal alignment film, and a liquid crystal display element. The disclosed liquid crystal aligning agent is characterized by containing at least one polymer (A) that is selected from the group consisting of polyimide precursors having a structural unit represented by formula (1) and a structural unit represented by formula (2) and imidized polymers of the polyimide precursors. In the formulae, the symbols are as defined in the description.

Description

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

The present invention relates to a liquid crystal alignment agent suitable for a photo-alignment method, a liquid crystal alignment film obtained by using the liquid crystal alignment agent, and a liquid crystal display element obtained by using the liquid crystal alignment film.

A liquid crystal display element used in a liquid crystal television, a liquid crystal display, or the like is generally provided with a liquid crystal alignment film in the element for controlling the alignment state of the liquid crystal and the like. The liquid crystal alignment film is mainly a liquid crystal alignment agent mainly composed of a polyimide precursor such as polyamic acid (polyamic acid) or a solution of a soluble polyimide, and is coated on a glass substrate and then fired. A polyimide-based liquid crystal alignment film obtained by baking. At present, the most popular method in the industry is that the liquid crystal alignment film is made of cloth such as cotton, nylon, polyester, etc., and the surface of the polyimide liquid crystal alignment film formed on the electrode substrate is wiped in one direction. Made by processing.

The photo-alignment method is an alignment processing method that does not require friction, and has the advantage that it can be produced industrially with a simple manufacturing process. Therefore, it is a liquid crystal display element driven by an IPS driving method or a wide-view opening and closing (hereinafter, FFS) driving method. In comparison, when the liquid crystal alignment film obtained by the light alignment method is used, compared with the liquid crystal alignment film obtained by the rubbing treatment method, the liquid crystal display can be improved because of the contrast of the liquid crystal display element or the improvement of the viewing angle characteristics. The performance of the device has attracted attention with its excellent liquid crystal alignment processing method.

However, the liquid crystal alignment film obtained by the light alignment method still has a problem that the anisotropy of the alignment direction of the polymer film is small when compared with a rubbing processor. When the anisotropy is small, sufficient liquid crystal alignment cannot be obtained, and when used as a liquid crystal display element, problems such as afterimages may occur. As a method for improving the anisotropy of a liquid crystal alignment film obtained by a photo-alignment method, a proposal has been proposed to remove low-molecular-weight components generated by cutting the main chain of the polyfluorene imine by light irradiation after light irradiation.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Laid-Open No. 9-297313

[Patent Document 2] Japanese Patent Laid-Open No. 2011-107266

    [Non-patent literature]    

[Non-Patent Document 1] "Liquid Crystal Alignment Film" Kisaki Waki, Ichimura Functional Materials November 1997 Vol.17 No.11 Page 13-22

In the liquid crystal display element of the IPS driving method or the FFS driving method, a positive type liquid crystal has been used in the past, but when a negative type liquid crystal is used, the penetration loss at the upper part of the electrode can be reduced, and the contrast can be improved. When using a liquid crystal alignment film obtained by a photo-alignment method and a liquid crystal display element of an IPS driving method or an FFS driving method of a negative liquid crystal, it is expected that the liquid crystal display element has higher display performance than a conventional liquid crystal display element.

However, the inventor of the present case has researched and found that the liquid crystal alignment film obtained by light alignment has a higher incidence of poor display (bright spots) when using a liquid crystal display element of negative liquid crystal, which causes display failure. Good question.

An object of the present invention is to provide a liquid crystal alignment agent suitable for a photo-alignment method for a liquid-crystal alignment film for a photo-alignment method that does not generate bright spots and can obtain good afterimage characteristics even when a negative-type liquid crystal is used. A liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment agent.

As a result of intensive research, the present inventors have found that a liquid crystal alignment agent containing a polyfluorene-imide polymer having a specific structure is effective for achieving the above-mentioned object, and thus completed the present invention.

The gist of the present invention is as described below.

A liquid crystal alignment agent, comprising a polyimide precursor having a structural unit represented by the following formula (1) and the following formula (2), and a polyimide precursor of the polyimide precursor At least one polymer (A) selected from the group consisting of aminated polymers.

(In formulas (1) and (2), X ₁ and X ₂ each independently represent a tetravalent organic group, R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, A ₁ , A ₂ , A ₃ , and A ₄ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Z ₁ , Z ₂ , Z ₃ , and Z ₄ each independently represent a hydrogen atom, a halogen atom, and a carbon number 1 ~ 4 alkyl, n is an integer from 1 to 4).

According to the content of the present invention, it is possible to provide a liquid crystal alignment film that can suppress the bright spots generated by the photo-alignment processing method even when a negative type liquid crystal is used, and can produce a liquid crystal alignment film with high illumination sensitivity and good afterimage characteristics. Liquid crystal alignment agent suitable for photo-alignment processing. When the liquid crystal alignment film obtained from the liquid crystal alignment agent is provided, a liquid crystal display element having no display defect and high reliability can be provided.

     [Form of Implementing Invention]           <Specific polymer>     

As described above, the liquid crystal alignment agent of the present invention contains a polyimide precursor having a structural unit represented by the formula (1) and the formula (2), and a polyimide precursor of the polyimide precursor. A polymer of at least one selected from a group of aminated polymers (also referred to as a specific polymer (A)).

In formula (1) and formula (2), R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. A hydrogen atom or a methyl group is particularly preferable from the viewpoint that the fluorene imidization can be easily performed by heating. X ₁ and X ₂ are tetravalent organic groups. It is preferred that a structure that imparts anisotropy is a reaction that can be decomposed or isomerized by irradiation with ultraviolet rays. It is a group formed by the structures represented by the following formulae (X1-1) to (X1-9). At least one selected is preferable.

In formula (X1-1), R ₃ , R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group , Or phenyl, which may be the same or different. From the viewpoint of liquid crystal alignment, R ₃ , R ₄ , R ₅ , and R _{6 are} preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group. Specific structures of the formula (X1-1) include, for example, structures represented by the following formulae (X1-10) to (X1-11). From the viewpoint of liquid crystal alignment and sensitivity, (X1-11) is particularly preferred.

In Formula (1) and Formula (2), A ₁ , A ₂ , A ₃ , and A ₄ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. From the viewpoint of liquid crystal alignment, a hydrogen atom or a methyl group is preferable, and a hydrogen atom is more preferable.

In formulae (1) and (2), Z ₁ , Z ₂ , Z ₃ , and Z ₄ each independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. From the viewpoint of liquid crystal alignment, a hydrogen atom, a halogen atom, or a methyl group is preferred. n is an integer from 1 to 4.

In the specific polymer (A), from the viewpoint of liquid crystal alignment and suppression of bright spots, the ratio of the structural unit represented by the above formula (1) is preferably 10 to 50 mol% with respect to 1 mol of the full structural unit. , More preferably 30-50 mol%.

In addition, in the specific polymer (A), the content ratio of the structural unit represented by the above formula (2) is 20 to 90 mol relative to 1 mol of the full structural unit from the viewpoint of liquid crystal alignment and suppression of bright spots. % Is better, more preferably 20 to 50 mole%.

For the specific polymer (A), from the viewpoint of the mechanical strength of the alignment film, in addition to the structural units represented by the above-mentioned formulas (1) and (2), it is preferable to have the structural unit represented by the following formula (3). .

In the formula (3), X ₃ includes a preferable example, and has the same meaning as X ₁ and X _{2 in} the formulas (1) and (2). R ₃ , including its preferred examples, has the same meaning as R ₁ and R ₂ described above. Y ₁ is at least one selected from the group consisting of the structures represented by the following formulas [1d-1] to [1d-7].

In the above formulae [1d-1] to [1d-7], D is a tert-butoxymethoxycarbonyl group. n ₁ to n ₅ each independently represent an integer of 1 to 5.

More specific examples of Y ₁ include the following formulas [1d1-1] to [1d1-6] and the like.

In the above [1d1-1] to [1d1-6], D is a tert-butoxymethoxycarbonyl group.

The content ratio of the structural unit represented by the formula (3) is preferably 10 to 50 mol%, more preferably 20 to 30 mol%, relative to 1 mol of the full structural unit of the specific polymer (A).

The specific polymer (A) may further include a polyimide precursor containing the structural unit represented by the following formula (4) in addition to the structural unit represented by the formulae (1) to (3), and the polyfluorene Imine precursor.

In formula (4), R ₄ , including its preferred examples, has the same meaning as R ₁ in formula (1). A ₅ and A ₆ , including their preferred examples, have the same meaning as A ₁ and A _{2 in} the formula (1). X is a tetravalent organic group, and its structure is not particularly limited.

When specific examples are given, for example, the above formulae (X1-1) to (X1-9) or the following formulae (X-9) to (X-42) can be cited. From the viewpoint of easily obtaining a compound, X can be exemplified by X1-1 to X1-9, X-17, X-25, X-26, X-27, X-28, X-32, or X-39. In addition, from the viewpoint of using a DC voltage to reduce the accumulated residual charge and to obtain a liquid crystal alignment film at an early stage, a tetracarboxylic dianhydride having an aromatic ring structure is preferred. X is X-26, X-27, X -28, X-32, X-35, or X-37 is preferred.

In the above formula (4), Y is a divalent organic group, and its structure is not particularly limited. Specific examples of Y ₂ include the following formulae (Y-1) to (Y-84).

For the purpose of improving the alignment of the liquid crystal, Y is preferably a structure having a high linearity. For example, Y-7, Y-43 to Y-48, Y63, or Y-71 to Y-76 is preferable. From the viewpoint of using a DC voltage to ease the accumulated residual charge and to obtain a liquid crystal alignment film at an early stage, Y-77 to Y-84 are preferred.

     <Manufacturing Method of Polyurethane>     

The polyamidate precursor of the polyamidoimide precursor used in the present invention can be synthesized by the method (1), (2), or (3) shown below.

     (1) When synthesized from polyamic acid     

Polyamidate can be synthesized by esterifying a polycarboxylic acid obtained from a tetracarboxylic dianhydride and a diamine.

Specifically, for example, the polyamic acid and the esterifying agent are subjected to -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C, for 30 minutes to 24 hours. It is preferably synthesized in 1 to 4 hours.

The esterifying agent is preferably one which can be easily removed by purification, and examples thereof include N, N-dimethylformamide dimethyl acetal, and N, N-dimethylformamide diethyl acetal. Aldehyde, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide dineopentylbutyl acetal, N, N-dimethylformamide di-t -Butyl acetal, 1-methyl-3-p-tolyl triazene, 1-ethyl-3-p-tolyl triazene, 1-propyl-3-p-tolyl triazene , 4- (4,6-dimethoxy-1,3,5-tri 2-yl) -4-methylmorpholinium chloride and the like. The amount of the esterifying agent is preferably 2 to 6 mol equivalents relative to the repeating unit of polyamic acid at 1 mol.

The solvent used in the above reaction is preferably N, N-dimethylformamide, n-methyl-2-pyrrolidone, or γ-butyrolactone in terms of the solubility of the polymer. You can use 1 type or 2 types or more. The concentration at the time of synthesis is difficult to cause precipitation of a polymer, and it is easy to obtain a polymer. From 1 to 30% by mass, more preferably from 5 to 20% by mass.

     (2) Case where tetracarboxylic diester dichloride is reacted with amine     

Polyamidate can be synthesized via a tetracarboxylic acid diester dichloride and a diamine.

Specifically, for example, the tetracarboxylic acid diester dichloride and diamine are carried out in the presence of a base and an organic solvent at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C, for 30 minutes. ~ 24 hours, preferably 1 ~ 4 hours.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine, and the like can be used, but in order to stabilize the reaction, it is preferable to use pyridine. The amount of the alkali added is an amount that can be easily removed and a polymer can be easily produced. It is preferably 2 to 4 times more moles than the tetracarboxylic acid diester dichloride.

From the viewpoint of the solubility of the monomers and polymers, the solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or γ-butyrolactone. These may be used singly or in combination of two or more kinds. Both are OK. The polymer concentration during synthesis is difficult to cause the precipitation of the polymer, and it is easy to obtain a polymer, from 1 to 30% by mass, more preferably from 5 to 20% by mass. In addition, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, it is better to use the solvent used in the synthesis of polyamidate as much as possible to dehydrate, and it is better to prevent the external gas in a nitrogen atmosphere. .

     (3) Case where tetracarboxylic diester is reacted with diamine     

Polyamidate can be synthesized by polycondensing a tetracarboxylic diester and a diamine.

Specifically, for example, a tetracarboxylic diester and a diamine are carried out in the presence of a condensing agent, a base, and an organic solvent at 0 ° C to 150 ° C, preferably 0 ° C to 100 ° C, for 30 minutes. It can be synthesized by a reaction of ~ 24 hours, preferably 3 to 15 hours.

As the condensing agent, triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, dimethoxy-1,3,5-tri Methylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethylurea tetrafluoroborate, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethylurea hexafluorophosphate, (2,3-dihydro-2-thioxan-3-benzoxazolyl) phosphonic acid diphenyl Esters, etc. The addition amount of the condensing agent is preferably 2 to 3 times the mole of the tetracarboxylic acid diester.

Among the aforementioned bases, tertiary amines such as pyridine and triethylamine can also be used. The amount of the alkali added can be easily removed, and a polymer can be easily obtained, and it is preferably 2 to 4 times the mole of the diamine component.

In addition, when the Lewis acid is added as an additive in the above reaction, the reaction can be efficiently performed. The Lewis acid is preferably a lithium halide such as lithium chloride or lithium bromide. The amount of Lewis acid added is 0 to 1.0 times mole compared to the diamine component.

Among the above three synthetic methods of polyamic acid esters, the synthetic method of (1) or (2) above is particularly preferable from the viewpoint that a high molecular weight poly (fluorinated acid ester) can be obtained.

The polymer solution obtained by the above-mentioned method can be precipitated into the poor solvent by injecting it into a poor solvent under sufficient stirring. After carrying out precipitation several times, washing with a lean solvent, and drying at room temperature or heating, a refined polyamidate powder can be obtained. The lean solvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, cellosolve, acetone, and toluene.

     <Manufacturing method of polyamic acid>     

The polyamidic acid of the polyamidoimide precursor used in the present invention can be synthesized according to the method shown below.

Specifically, for example, a tetracarboxylic dianhydride and a diamine in the presence of an organic solvent are carried out at a temperature of -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C, for 30 minutes to 24 hours. It can be synthesized by a reaction method of 1 to 12 hours.

The organic solvent used in the above reaction is N, N-dimethylformamide, N-methyl-2-pyrrolidone, or γ-butyrolactone in terms of the solubility of the monomers and polymers. Preferably, one or two or more of them can be used. In terms of the concentration of the polymer, it is not easy to cause the precipitation of the polymer, and it is easy to obtain a polymer, and 1 to 30% by mass is preferable, and 5 to 20% by mass is more preferable.

The polyamic acid obtained in the above manner can be used to precipitate and recover the polymer by injecting the reaction solution into a lean solvent while stirring the reaction solution sufficiently. In addition, after carrying out precipitation several times, washing with a lean solvent, and drying at room temperature or heating, a purified polyamic acid powder can be obtained. Examples of the lean solvent include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

     <Manufacturing method of polyimide>     

The polyfluorene imine used in the present invention can be prepared by the above-mentioned polyphosphonium acid ester or polyphosphonium acid through amidation. In the case of producing polyimide from polyamic acid ester, an alkaline catalyst is added to the polyamic acid solution, or a polyamic acid solution obtained by dissolving polyamic acid resin powder in an organic solvent. The chemical fluorene imidization of the vehicle is a simple method. Chemical fluorene imidization, fluorene imidization can be carried out at a lower temperature, it is preferred that it does not cause the molecular weight of the polymer to decrease during fluorene imidization.

Chemical ammonium imidization is performed by stirring a polyammonium ester which is to be imidized in the presence of a basic catalyst in an organic solvent. As the organic solvent, a solvent used in the aforementioned polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, in order to cause triethylamine to react, it is preferable to maintain sufficient basicity.

The temperature at which the amidine imidization reaction is performed is -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time is preferably 1 to 100 hours. The amount of the alkaline catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times. The hydrazone imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time. Since the added catalyst and the like remain in the solution after the imidization reaction, the obtained imidization polymer can be recovered according to the methods described below and re-dissolved in an organic solvent as a liquid crystal. Users of alignment agents are preferred.

In the case of producing polyimide from polyacrylic acid, it is simple to add a catalyst chemically imidized to the solution of the polyamidic acid obtained by reacting a diamine component with a tetracarboxylic dianhydride. method. Chemical fluorene imidization, fluorene imidization reaction can be carried out at a lower temperature, it is not easy to cause the molecular weight of the polymer to decrease during fluorene imidization, and it is preferred.

Chemical ammonium imidization can be carried out by stirring the polymer to be imidized in the presence of a basic catalyst and an acid anhydride in an organic solvent. As the organic solvent, a solvent used in the aforementioned polymerization reaction can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, in order to make pyridine react, it is preferable to have a suitable basicity. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Among them, when acetic anhydride is used, it is preferable to facilitate purification after completion of the reaction.

The temperature at which the amidine imidization reaction is performed is -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time can be performed in 1 to 100 hours. The amount of the alkaline catalyst is 0.5 to 30 mol times of the amino acid group, preferably 2 to 20 mol times, and the amount of the acid anhydride is 1 to 50 mol times of the amino acid group, preferably 3 to 30 mol times. The hydrazone imidization rate of the obtained polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.

The added catalyst and the like remain in the solution after the polyimide or polyimide imidization reaction, so the obtained imidized polymer can be recovered through the following methods to make it Redissolved in an organic solvent is preferred as the liquid crystal alignment agent of the present invention.

The polyimide solution obtained in the above manner is poured into a poor solvent under sufficient stirring to precipitate a polymer. After carrying out precipitation several times, washing with a lean solvent, and drying at room temperature or heating, a purified polyurethane powder can be obtained.

The poor solvent is not particularly limited, and examples thereof include methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, and benzene.

     <Liquid crystal alignment agent>     

The liquid crystal alignment agent used in the present invention has a solution form obtained by dissolving a specific polymer (A) in an organic solvent. The molecular weight of the specific polymer (A) is preferably a weight average molecular weight of 2,000 to 500,000, more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and still more preferably 5,000 to 50,000.

The concentration of the polymer in the liquid crystal alignment agent can be appropriately changed according to the thickness of the coating film to be formed. However, when a uniform and defect-free coating film is formed, it is preferably 1% by weight or more, and the solution is stored. In terms of stability, it is preferably 10% by weight or less.

The solvent used in the liquid crystal alignment agent of the present invention is not particularly limited as long as it is a solvent (also referred to as a good solvent) that can dissolve the specific polymer (A). The following are specific examples of good solvents.

For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylimine Samarium, γ-butyrolactone, 1,3-dimethyl-imidazolinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, and the like. Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and γ-butyrolactone are more preferably used.

From the viewpoint of improving the solubility of the specific polymer (A) in a solvent, the solvents represented by the following formulas [D-1] to [D-3] are preferred.

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

The content of the good solvent in the liquid crystal alignment agent is preferably 20 to 99% by mass of the entire solvent, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass.

The liquid crystal alignment agent may contain a solvent (also referred to as a lean solvent) that can improve the coating property or surface smoothness of the liquid crystal alignment film when the liquid crystal alignment agent is applied. The lean solvents are preferably 1 to 80% by mass of the entire solvent contained in the liquid crystal alignment agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass.

The following are specific examples of lean solvents.

Ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, Isoamyl alcohol, tert-pentanol, 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-methyl Cyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2- Butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-methyl-2,4- Pentanediol, 2-ethyl-1,3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol Alcohol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 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 Ester, 2-ethylhexyl acetate Ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol Monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol, 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 3-ethoxypropionate Esters, ethyl 3-methoxypropionate, 3- Propoxylic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-lactic acid Butyl ester, isoamyl lactate, or the aforementioned formulas [D-1] to [D-3].

Among them, 1-hexanol, cyclohexanol, 1,2-ethanediol, 1,2-propanediol, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, or dipropylene glycol dimethyl ether are more preferable.

In the liquid crystal alignment agent of the present invention, a crosslinkable compound having an epoxy group, an isocyanato group, an oxycyclobutane group, or a cyclic carbonate group is introduced, and the compound is composed of a hydroxyl group, a hydroxyalkyl group, and a lower alkoxyalkyl group. A cross-linking compound having at least one kind of substituent selected from a group or a cross-linking compound having a polymerizable unsaturated bond is preferred. These substituents or polymerizable unsaturated bonds must have two or more in the crosslinkable compound.

Crosslinkable compounds having an epoxy group or an isocyanate group, for example, bisphenol acetone glycidyl ether, phenol-phenol novolac epoxy resin, cresol-novolac epoxy resin, triglycidyl isocyanurate , Tetraglycidylamino diphenyl ester, tetraglycidyl-m-xylene diamine, tetraglycidyl-1,3-bis (aminoethyl) cyclohexane, tetraphenylglycidyl ether ethane, tris Phenyl glycidyl ether ethane, bisphenol hexafluoroacetic acid diglycidyl ether, 1,3-bis (1- (2,3-glycidoxy) -1-trifluoromethyl-2,2,2 -Trifluoromethyl) benzene, 4,4-bis (2,3-glycidoxy) octylfluorobiphenyl, triglycidyl-p-aminophenol, tetraglycidylmethylxylene diamine, 2 -(4- (2,3-glycidoxy) phenyl) -2- (4- (1,1-bis (4- (2,3-glycidoxy) phenyl) ethyl) Phenyl) propane or 1,3-bis (4- (1- (4- (2,3-glycidoxy) phenyl) -1- (4- (1- (4- (2,3- Glycidoxy) phenyl) -1-methylethyl) phenyl) ethyl) phenoxy) -2-propanol and the like.

Examples of the crosslinkable compound having an oxycyclobutane group include compounds having at least two oxycyclobutane groups represented by the following formula [4A].

Specifically, the crosslinkable compound shown by the formula [4a]-a formula [4k] etc. which are disclosed on page 58-59 of International Publication WO2011 / 132751 (2011.10.27 publication) is mentioned.

Examples of the crosslinkable compound having a cyclic carbonate group include crosslinkable compounds having at least two cyclic carbonate groups represented by the following formula [5A].

Specific examples include crosslinkable compounds represented by formulas [5-1] to [5-42] disclosed on pages 76 to 82 of International Publication WO2012 / 014898 (2012.2.2). .

A crosslinkable compound having at least one selected from the group consisting of a hydroxyl group and an alkoxy group, for example, an amine-based resin having a hydroxyl group or an alkoxy group, for example, a melamine resin, a urea resin, fluorene Resin, acetylene urea-formaldehyde resin, succinamide-formaldehyde resin or ethylene urea-formaldehyde resin, etc. Specifically, for example, a melamine derivative in which a hydrogen atom in an amine group is replaced with a methylol group or an alkoxymethyl group, or a benzofluorene can be used. Derivatives, or acetylene urea. The melamine derivative or benzofluorene Derivatives can exist as dimers or trimers. Should take every three The ring preferably has 3 to 6 hydroxymethyl or alkoxymethyl groups on average.

The melamine derivative or benzopyrene Derivatives, for example, each of the three The ring has an average of 3.7 methoxymethyl substituted MX-750, each three Rings have an average of 5.8 methoxymethyl-substituted MW-30 (above, manufactured by Sanwa Chemical Co., Ltd.) or CYMEL-300, 301, 303, 350, 370, 771, 325, 327, 703, 712, etc. Methylated melamine, CYMEL-235, 236, 238, 212, 253, 254, etc.Methoxymethylated butoxymethylated melamine, CYMEL-506, 508, etc.Butoxymethylated melamine, CYMEL-1141, etc. Methoxymethylated isobutoxymethylated melamine of carboxyl group, methoxymethylated ethoxymethylated benzopyrene such as CYMEL-1123 Methoxymethylated butoxymethylated benzopyrene, CYMEL-1123-10, etc. , CYMEL-1128, etc. , CYMEL-1125-80 and other carboxyl-containing methoxymethylated ethoxymethylated benzopyrene (Above, manufactured by Mitsui Cyanoamide Corporation) and the like.

Examples of the acetylene urea include butoxymethylated acetylene urea such as CYMEL-1170, hydroxymethylated acetylene urea such as CYMEL-1172, and methoxymethylolated acetylene urea such as POWERLINK-1174.

Benzene or phenolic compound having a hydroxy or alkoxy group, for example, 1,3,5-ginseno (methoxymethyl) benzene, 1,2,4-gins (isopropoxymethyl) benzene, 1,4- Bis (sec-butoxymethyl) benzene or 2,6-dimethylol-p-tert-butanol.

More specifically, examples thereof include crosslinkable compounds of the formulas [6-1] to [6-48] disclosed on pages 62 to 66 of International Publication WO2011 / 132751 (published on 2011.10.27).

Crosslinkable compounds having polymerizable unsaturated bonds, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, tris (methyl) Cross-linking compounds having 3 polymerizable unsaturated groups in the molecule, such as acrylfluorenyloxyethoxytrimethylolpropane or glycerol polyglycidyl ether poly (meth) acrylate, for example, ethylene glycol Di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) Acrylate, polypropylene glycol di (meth) acrylate, butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide bisphenol A type di (meth) acrylic acid Ester, propylene oxide bisphenol type di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, pentaerythritol di (meth) acrylic acid Ester, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, phthalic acid di shrink Cross-linking compounds with two polymerizable unsaturated groups in the molecule, such as glyceride di (meth) acrylate or hydroxypivalate neopentyl glycol di (meth) acrylate, for example, 2-hydroxyethyl ester (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-phenoxy-2-hydroxypropyl (meth) acrylate, 2 -(Meth) acryloxy-2-hydroxypropyl phthalate, 3-chloro-2-hydroxypropyl (meth) acrylate, glycerol mono (meth) acrylate, 2- ( Crosslinkable compounds having one polymerizable unsaturated group in the molecule, such as meth) acrylfluorenyloxyethyl phosphate or N-hydroxymethyl (meth) acrylamide, and the like.

Alternatively, a compound represented by the following formula [7A] may be used.

(In formula [7A], E ₁ represents a group selected from a cyclohexane ring, a bicyclohexane ring, a benzene ring, a biphenyl ring, a bitriphenyl ring, a naphthalene ring, a fluorene ring, an anthracene ring, or a phenanthrene ring. E ₂ represents a base selected by the following formula [7a] or [7b], and n represents an integer of 1 to 4).

The above is an example of a crosslinkable compound, but it is not limited to these. The crosslinkable compound used for the liquid crystal alignment agent may be used alone or in combination of two or more kinds.

The content of the crosslinkable compound in the liquid crystal alignment agent is preferably 0.1 to 150 parts by mass relative to 100 parts by mass of the entire polymer component. Among them, from the viewpoint of producing the desired effect due to the crosslinking reaction, it is preferably 0.1 to 100 parts by mass relative to 100 parts by mass of the entire polymer component. More preferably, it is 1 to 50 parts by mass.

The liquid crystal alignment agent of the present invention may be a compound that can improve the uniformity of the thickness of the liquid crystal alignment film or the surface smoothness when the liquid crystal alignment agent is applied.

Examples of the compound that improves the uniformity or surface smoothness of the liquid crystal alignment film include fluorine-based surfactants, polysiloxane-based surfactants, and non-ionic surfactants.

More specifically, examples include F-Top EF301, EF303, EF352 (above, manufactured by Dow Chemical Co., Ltd.), Megaface F171, F173, R-30 (above, manufactured by Dainippon Paint Co., Ltd.), FLUORAD FC430, FC431 (Above, manufactured by Sumitomo 3M), AsahiGuard AG710, SurflonS-382, SC101, SC102, SC103, SC104, SC105, SC106 (above, manufactured by Asahi Glass Co., Ltd.) and the like.

The amount of the surfactant used is preferably 0.01 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, relative to 100 parts by mass of the entire polymer component contained in the liquid crystal alignment agent.

In addition, a liquid crystal alignment agent may be added with a compound that promotes the charge movement in the liquid crystal alignment film and removes the charge from the device. For example, as disclosed in pages 69 to 73 of International Publication WO2011 / 132751 (2011.10.27) The nitrogen represented by the formulas [M1] to [M156] contains a heterocyclic amine compound. The amine compound may be directly added to the liquid crystal alignment agent, but it is preferably added as a solution having a concentration of 0.1 to 10% by mass, preferably 1 to 7% by mass. The solvent is not particularly limited as long as it can dissolve the specific polymer (A).

In the liquid crystal alignment agent of the present invention, in addition to the above-mentioned poor solvents, crosslinkable compounds, compounds that can improve the uniformity or surface smoothness of the thickness of the resin film or liquid crystal alignment film, and compounds that promote charge removal, as long as they do not damage In the range of the effect of the present invention, a polymer other than the polymer described in the present invention may be further added, a silane coupling agent for the purpose of improving the adhesiveness between the alignment film and the substrate, and even when the coating film is baked, it can effectively promote the A polyimide precursor, such as a polyimide precursor, is heated for the purpose of heating the polyimide precursor.

     <Liquid crystal alignment film and liquid crystal display element>     

The liquid crystal alignment film is a film obtained by applying the liquid crystal alignment agent to a substrate, and drying and baking the liquid crystal alignment agent. The substrate to which the liquid crystal alignment agent of the present invention can be applied is not particularly limited as long as it is a substrate having high transparency. In addition to a glass substrate and a silicon nitride substrate, an acrylic substrate or a polycarbonate substrate can be used. Plastic substrates. In this case, when a substrate formed with an ITO electrode or the like used for the purpose of driving liquid crystal is used, it is preferable from the viewpoint of simplification of the manufacturing process. Moreover, in a reflective liquid crystal display element, when only a single-sided substrate is used, an opaque object such as a silicon wafer may be used, and in this case, an electrode that can reflect light such as aluminum may also be used.

The application method of the liquid crystal alignment agent is not particularly limited, and industrially, generally, a method such as screen printing, lithography, flexo printing, or inkjet method is used. Other coating methods include, for example, a dipping method, a roll coating method, a slit coating method, a spin coater method, or a spray method, and these methods can be used according to the purpose.

After the liquid crystal alignment agent is coated on the substrate, the liquid crystal alignment film can be formed by evaporating the solvent through heating means such as a hot plate, a thermal cycle type oven, or an IR (infrared) type oven. The steps of drying and baking after applying the liquid crystal alignment agent of the present invention can be selected at any temperature and time. Usually, for example, the solvent is sufficiently removed at 50 to 120 ° C for 1 to 10 minutes, followed by 150 to 300 ° C for 5 to 120 minutes. When the thickness of the liquid crystal alignment film after firing is too thin, the reliability of the liquid crystal display element may be reduced. Therefore, 5 to 300 nm is preferable, and 10 to 200 nm is more preferable.

Although the rubbing treatment method can be used for the alignment treatment of the liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, the photo alignment treatment method is more preferable. A preferred example of the photo-alignment treatment method is to irradiate the surface of the liquid crystal alignment film with radiation deflected in a certain direction. Depending on the situation, it is preferred to perform heat treatment at a temperature of 150 to 250 ° C to impart liquid crystal alignment ( Also known as liquid crystal alignment capability). As the radiation, ultraviolet rays or visible rays having a wavelength of 100 to 800 nm can be used. Among them, ultraviolet rays having a wavelength of 100 to 400 nm are preferred, and wavelengths of 200 to 400 nm are more preferred.

From the viewpoint of improving the alignment of the liquid crystal, the substrate coated with the liquid crystal alignment film may be heated to 50 to 250 ° C. and irradiated with radiation. The radiation dose is preferably 1 to 10,000 mJ / cm ^{2, and more} preferably 100 to 5,000 mJ / cm ² . The liquid crystal alignment film thus obtained can make liquid crystal molecules form an alignment stably in a certain direction.

The higher the extinction ratio of polarized ultraviolet rays, the better the anisotropy can be provided. Specifically, for example, the extinction ratio of ultraviolet rays that are linearly polarized is preferably 10: 1 or more, and more preferably 20: 1 or more.

In addition, in the aforementioned method, contact treatment may be performed on the liquid crystal alignment film irradiated with polarized radiation using water, a solvent, or the like.

The solvent used for the above-mentioned contact treatment is not particularly limited as long as it can dissolve a decomposed product generated from the liquid crystal alignment film by irradiation of radiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, and butyl cellosolve ( cellosolve), ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, or cyclohexyl acetate, and the like. Among them, water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate are preferred from the viewpoint of general versatility or safety of the solvent, and water, 1-methoxy-2-propane Alcohol or ethyl lactate are preferred. As the solvent, one kind or a combination of two or more kinds can be used.

The contact treatment, for example, a treatment of water or a solvent applied to a liquid crystal alignment film irradiated with polarized radiation may include a dipping treatment or a spray treatment (Spray treatment). The time during these processes can efficiently dissolve the decomposition products generated by the liquid crystal alignment film due to radiation, and it is preferably 10 seconds to 1 hour, and the dipping treatment is performed for 1 minute to 30 minutes Those are better. The solvent used in the contact treatment may be normal temperature or heated, and preferably 10 to 80 ° C. Among them, it is preferably 20 ~ 50 ° C. In addition, from the viewpoint of the solubility of the decomposed product, ultrasonic treatment may be performed in accordance with the necessary surname.

After the aforementioned contact treatment, it is preferable to use a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone for rinsing (also referred to as "washing") or baking the liquid crystal alignment film. In this case, either washing or baking may be performed, or both. The baking temperature is preferably 150 to 300 ° C, more preferably 180 to 250 ° C, and particularly preferably 200 to 230 ° C. The baking time is preferably 10 seconds to 30 minutes, and more preferably 1 to 10 minutes.

The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for a liquid crystal display element of a transverse electric field method such as an IPS method or an FFS method, and is particularly suitable for a liquid crystal display device of an FFS method. The liquid crystal display element can be obtained by preparing a liquid crystal cell using a known method after preparing a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention.

An example of a method for manufacturing a liquid crystal cell will be described by taking a liquid crystal display element having a passive element matrix structure as an example. In addition, each pixel portion constituting a display image may be a liquid crystal display element having an active matrix structure provided with switching elements such as a TFT (Thin Film Transistor).

Specifically, for example, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be formed, for example, as ITO electrodes, and patterning a desired display image is performed. Next, an insulating film covering the common electrode and the segment electrode may be provided on each substrate. The insulating film may be, for example, a film of SiO ₂ -TiO ₂ formed by a sol-gel method.

Next, a liquid crystal alignment film is formed on each substrate, and one side substrate and the other substrate are overlapped with the liquid crystal alignment film surface facing each other, and the periphery is adhered with a sealant. When the sealant is used to control the gap of the substrate, a spacer can usually be mixed, and in the inner portion of the surface where the sealant is not provided, a spacer for controlling the gap of the substrate is also preferred. A part of the sealant is provided with an opening that can be filled with liquid crystal from the outside.

Next, a liquid crystal material is injected into a space surrounded by two substrates and the sealant through an opening provided in the sealant, and then the opening is sealed with an adhesive. For the injection method, a vacuum injection method may be used, and a capillary phenomenon may be used in the atmosphere. The liquid crystal material may be any of a positive type liquid crystal material and a negative type liquid crystal material, and a negative type liquid crystal material is preferred. Next, set the polarizer. Specifically, for example, a pair of polarizing plates can be attached to the surface of the liquid crystal layer of two substrates on the opposite side.

As described above, when the liquid crystal alignment agent of the present invention is used, a liquid crystal alignment film having both the ability to suppress the residual image generated by the AC drive and the adhesion of the sealant and the underlying substrate can be obtained. In particular, it is useful for a liquid crystal alignment film for a light alignment treatment method that irradiates polarized radiation.

    [Example]    

Examples will be listed below to describe the present invention in more detail, but the present invention is not limited by these explanations.

The following are abbreviations of the compounds used and the measurement methods.

NMP: N-methyl-2-pyrrolidone, BCS: butyl cellosolve

DA-1: 1,2-bis (4-aminophenoxy) ethane

DA-2: 1,3-bis (4-aminophenoxy) propane

DA-3: p-phenylenediamine

DA-6: 4- (2- (methylamino) ethyl) aniline

    [Viscosity]    

The viscosity of the polyamic acid ester and polyamic acid solution is an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.), with a sample volume of 1.1 mL, Conerotar TE-1 (1 ° 34 ', R24), temperature Measured at 25 ° C.

    [Molecular weight]    

The molecular weight of the polyamidate is measured using a GPC (normal-temperature gel permeation chromatography) device, and the number-average molecular weight (hereinafter, also referred to as Mn) and weight are calculated based on polyethylene glycol and polyethylene oxide conversion values. Average molecular weight (hereinafter, also referred to as Mw).

GPC device: Shodex (GPC-101)

Column: Shodex (KD803, KD805 in-line)

Column temperature: 50 ℃

Eluent: N, N-dimethylformamide (additives: lithium bromide-water (LiBr‧H ₂ O) 30mmol / L, phosphoric acid‧anhydrous crystal (o-phosphoric acid) 30mmol / L, tetrahydrofuran (THF) 10ml / L)

Flow rate: 1.0ml / min

Standard samples for calibration line preparation: TSK standard polyethylene oxide (weight average molecular weight (Mw) about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corporation, and polyethylene glycol (wave peak) manufactured by Polymer Research Corporation Molecular weight (Mp) is about 12,000, 4,000, 1,000). In order to avoid overlapping peaks, two types of samples: 900,000, 100,000, 12,000, 1,000, etc., and three types of samples: 150,000, 30,000, and 4,000, etc. were measured separately.

    [Determination of imidization rate]    

20mg of polyimide powder was added to the NMR sample tube (NMR sample standard tube, 5 (manufactured by Kusano Science Co., Ltd.), deuterated dimethyl sulfene (DMSO-d6, 0.05% TMS (tetramethylsilane) mixed product) (0.53 ml) was added, and ultrasound was applied to completely dissolve it. A 500 MHz proton NMR in this solution was measured using an NMR measuring machine (JNW-ECA500) (manufactured by Japan Electronics Data). The hydrazone imidization rate is determined by using protons generated from structures that have not changed before and after hydrazone imidization as the reference protons. The peak value of the proton is calculated using the proton generated from the proton, and the sulfamic acid appears near 9.5 ppm to 10.0 ppm The proton wave integrated value generated by the NH group is obtained by the following calculation formula.

醯 Imidization rate (%) = (1-α‧x / y) × 100

In the above formula, in the case where x is the integrated value of the proton peak generated by the NH group of the amino acid, y is the integrated value of the peak value of the reference proton, and α is the poly (aminoimidization rate of 0%) The ratio of the number of reference protons to one NH matrix proton of ammonium acid.

    [Anisotropy of alignment film]    

The measurement was performed using a liquid crystal alignment film evaluation system "Rey‧ScanLab H" (LYS-LH30S-1A) manufactured by Moritex. A polyimide film having a film thickness of 100 nm was irradiated with ultraviolet rays through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained alignment film was measured.

    [Production of LCD cell]    

Production of a liquid crystal cell having a constituent content of a wide-angle field technology (Fringe Field Switching: FFS) mode liquid crystal display element.

First, prepare a substrate with electrodes. It is formed on a glass substrate having a length of 30 mm, a width of 0 mm, and a thickness of 0.7 mm. An ITO electrode having a solid pattern pattern as a counter electrode of the first layer is formed. The second layer on the counter electrode as the first layer is a SiN (silicon nitride) film formed by a CVD method. The SiN film of the second layer has a film thickness of 500 nm and has a function as an interlayer insulating film. On the second layer of the SiN film, a dentate pixel electrode formed by patterning as a third layer as an ITO film is arranged to form two pixels, such as a first pixel and a second pixel. Pixels. The size of each pixel is 10 mm in length and about 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 from each other through the action of the SiN film of the second layer.

The pixel electrode on the third layer has a dentate shape formed by a plurality of electrode elements in the shape of a "ㄑ" in which the central portion of the array is buckled. The width in the short-side direction of each electrode element is 3 μm, and the interval between the electrode elements is 6 μm. The pixel electrode forming each pixel is composed of a plurality of electrode elements with a bent "ㄑ" shape in the center of the array. Therefore, the shape of each pixel is not rectangular. It is the same as the electrode element. The central part is the shape of "ㄑ" which is approximately bold with a buckled shape. Therefore, each pixel is divided into an upper part and a lower part using the central buckling part as a realm, and has a first domain on the upper side and a second domain on the lower side.

When the first area and the second area of each pixel are compared, it is a case where the formation direction of the electrode elements constituting the pixel electrode is different. That is, when the rubbing direction of the liquid crystal alignment film described later is used as a reference, in the first area of the pixel, the electrode elements of the pixel electrode are formed at an angle of + 10 ° (clockwise), and in the second area of the pixel, the The electrode element of a plain electrode forms an angle (clockwise) of -10 °. In other words, in the first and second areas of each pixel, the liquid crystal caused by applying a voltage between the pixel electrode and the counter electrode has a turning action (plane, opening and closing) in the plane of the substrate. Compositions that oppose each other.

Next, the obtained liquid crystal alignment agent was filtered with a filter of 1.0 μm, and then the prepared substrate with the electrode and the glass having a columnar spacer with a height of 4 μm was formed on the inner surface of the substrate with an electrode using a spin coater. Substrate. After drying on a hot plate at 80 ° C for 5 minutes, baking was performed in a hot air circulation oven at 230 ° C for 20 minutes to form a coating film with a film thickness of 100 nm. This coating film surface was irradiated with a polarizing plate with ultraviolet light having a wavelength of 254 nm of linearly polarized light having an extinction ratio of 10: 1 or more. The substrate was immersed in at least one type of solvent selected from water and organic solvents for 3 minutes, followed by immersion in pure water for 1 minute, and heated on a heating plate at 150 ° C to 300 ° C for 5 minutes to obtain a liquid crystal alignment. Film substrate. Using the above two substrates as a group, a sealant was printed on the substrate, and the other substrate was bonded so as to face the liquid crystal alignment film surface with an orientation direction of 0 °, and then the sealant was hardened to obtain an empty cell. . A liquid crystal MLC-7026-100 (manufactured by Mok Corporation) was injected into the empty cell using a reduced pressure injection method, and then the injection port was sealed to obtain an FFS-driven liquid crystal cell. Subsequently, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour, and left for one night for each evaluation.

    [Evaluation of afterimage caused by long-term AC drive]    

A liquid crystal cell having the same structure as the liquid crystal cell used in the afterimage evaluation described above was prepared.

Under a constant temperature environment of 60 ° C, an AC voltage of ± 5V was applied to the liquid crystal cell at a frequency of 60 Hz for 120 hours. Subsequently, a short-circuit state is formed between the pixel electrode and the counter electrode of the liquid crystal cell, and it is left at room temperature for one day.

After being placed, the liquid crystal cell is placed between two polarizing plates whose polarizing axes are arranged in a vertical cross manner. After the backlight is turned on without applying a voltage, the arrangement angle of the liquid crystal cell is adjusted to transmit light. The minimum brightness. Then, from the darkest angle formed in the second area of the first pixel to the darkest angle formed in the first area, the rotation angle generated when the liquid crystal cell rotates is calculated as the angle Δ. The second pixel is also the same. After comparing the second area with the first area, the angle Δ is calculated similarly.

    [Evaluation of Bright Points of LCD Cells (Comparison)]    

The bright spots of the liquid crystal cell prepared above were evaluated. The evaluation of the bright point of the liquid crystal cell was performed by observing the liquid crystal cell using a polarizing microscope (ECLIPSE E600WPOL) (manufactured by Nikon Corporation). Specifically, for example, a liquid crystal cell can be observed using a polarized light microscope equipped with 稜鏡 and a magnification of 5 times, and the number of bright spots that can be confirmed can be calculated. Those above are marked as "bad".

    <Synthesis example 1>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA1 0.81 g (3.30 mmol), DA-2 0.57 g (2.20 mmol), DA-3 0.36 g (3.30 mmol), DA- 4 0.88 g (2.20 mmol), 29.99 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring this diamine solution, 1.35-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride 2.35 g (10.51 mmol) was added, and then 6.40 g of NMP was added to make it solid. The concentration of the ingredients was 12% by mass, and the mixture was stirred at room temperature for 24 hours to prepare a polyamic acid solution (A). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 316 mPa · s. The molecular weight of the polyamidic acid was Mn = 13230 and Mw = 29550.

    <Synthesis example 2>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA4 0.54 g (2.20 mmol), DA-2 0.85 g (3.30 mmol), DA-3 0.36 g (3.30 mmol), DA- 4 0.88 g (2.20 mmol), 30.17 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring this diamine solution, 2.35 g (10.51 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 6.34 g of NMP was added to make it a solid component. The concentration was 12% by mass, and the mixture was stirred at room temperature for 24 hours to prepare a polyamic acid solution (B). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 356 mPa · s. The molecular weight of this polyamidic acid was Mn = 14120 and Mw = 31210.

    <Synthesis example 3>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA-1 0.88 g (3.60 mmol), DA-2 0.31 g (1.20 mmol), DA-3 0.52 g (4.80 mmol), and DA- 4 0.96 g (2.40 mmol), 30.64 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring this diamine solution, 2.57 g (11.46 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 7.74 g of NMP was added to make the solid content concentration The content was 12% by mass, and the mixture was stirred at room temperature for 24 hours to obtain a polyamic acid solution (C). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 336 mPa · s. The molecular weight of this polyamidic acid was Mn = 13410 and Mw = 30110.

    <Synthesis example 4>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA1 0.54 g (2.20 mmol), DA-2 0.57 g (2.20 mmol), DA-3 0.48 g (4.40 mmol), and DA- 4 0.88 g (2.20 mmol), 28.27 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring this diamine solution, 1.35 g (10.51 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 7.03 g of NMP was added to achieve a solid content concentration of 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (D). The viscosity of the polyamidic acid solution at a temperature of 25 ° C was 366 mPa · s. The molecular weight of this polyamidic acid was Mn = 14530 and Mw = 36150.

    <Synthesis example 5>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh out DA-1 0.95 g (3.90 mmol), DA-2 0.67 g (2.60 mmol), DA-3 0.70 g (6.50 mmol), and add NMP 26.76 g was stirred under a nitrogen atmosphere to dissolve it. While stirring this diamine solution, 1.78 g (12.42 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 10.71 g of NMP was added to achieve a solid content concentration of 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (E). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 301 mPa · s. The molecular weight of the polyamidic acid was Mn = 11990 and Mw = 25310.

    <Synthesis example 6>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA1 0.81 g (3.30 mmol), DA-2 0.57 g (2.20 mmol), DA-3 0.36 g (3.30 mmol), DA- 5 0.75 g (2.20 mmol), 28.55 g of NMP was added, and the mixture was stirred under nitrogen to dissolve. While stirring this diamine solution, 2.35 g (10.51 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 6.93 g of NMP was added to make the solid content concentration reach 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (F). The viscosity of the polyamidic acid solution at a temperature of 25 ° C was 350 mPa · s. The molecular weight of this polyamidic acid was Mn = 15220 and Mw = 31850.

    <Synthesis example 7>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh DA-1 0.88 g (3.60 mmol), DA-3 0.65 g (6.00 mmol), DA-4 0.96 g (2.40 mmol), and add NMP 28.57 g was stirred under a nitrogen atmosphere to dissolve it. While stirring this diamine solution, 2.57 g (11.46 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 8.49 g of NMP was added to achieve a solid content concentration of 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (G). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 386 mPa · s. The molecular weight of this polyamidic acid was Mn = 16530 and Mw = 37220.

    <Synthesis example 8>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh 1.59 g (6.50 mmol) of DA-1 and 0.70 g (6.50 mmol) of DA-3, add 26.34 g of NMP, and stir under nitrogen. To make it dissolve. While stirring this diamine solution, 1.78 g (12.42 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 10.86 g of NMP was added to achieve a solid content concentration of 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (H). The viscosity of the polyamidic acid solution at a temperature of 25 ° C was 310 mPa · s. The molecular weight of this polyamidic acid was Mn = 13310 and Mw = 26210.

    <Synthesis example 9>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh 1.68 g (6.50 mmol) of DA-2 and 0.70 g (6.50 mmol) of DA-3, add 27.39 g of NMP, and stir under nitrogen. To make it dissolve. While stirring this diamine solution, 2.78 g (12.42 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 10.48 g of NMP was added to achieve a solid content concentration of 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (I). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 322 mPa · s. The molecular weight of the polyamidic acid was Mn = 14430 and Mw = 29950.

    <Synthesis example 10>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh 1.46 g (13.50 mmol) of DA-3 and 0.36 g (1.50 mmol) of DA-6, add 20.88 g of NMP, and stir under nitrogen. To make it dissolve. While stirring this diamine solution, 3.21 g (14.33 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and 15.98 g of NMP was added to make the solid content concentration reach 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (J). The viscosity of the polyamidic acid solution at a temperature of 25 ° C was 344 mPa · s. The molecular weight of this polyamidic acid was Mn = 14430 and Mw = 34850.

    <Synthesis example 11>    

In a 50 mL four-necked flask equipped with a stirring device and a nitrogen introduction tube, weigh 2.69 g (11.00 mmol) of DA-1, add 30.90 g of NMP, and stir under nitrogen to dissolve. While stirring this diamine solution, add 1.35-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride 2.35 g (10.51 mmol), and then add 6.07 g of NMP to make the solid content concentration reach 12 mass%, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution (K). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 367 mPa · s. The molecular weight of the polyamidic acid was Mn = 17110 and Mw = 33310.

    <Example 1>    

In a 100 ml Erlenmeyer flask, weigh 15.00 g of the 12% by mass polyamic acid solution (A) obtained in Synthesis Example 1, add NMP 9.00 g and BCS 6.00 g, and mix at 25 ° C for 8 hours to obtain a liquid crystal alignment agent. (1). In this liquid crystal alignment agent, no abnormal phenomenon such as turbidity or precipitation was found, and it was confirmed that the liquid crystal alignment agent was a uniform solution.

    <Examples 2 to 6>    

The liquid crystal alignment agents (2) to (2) to ((2) to (F)) were prepared in the same manner as in Example 1 except that each of the 12 mass% polyamic acid solutions (B) to (F) obtained in Synthesis Examples 2 to 6 was used. 6). No abnormal phenomenon such as turbidity or precipitation was found in any of these liquid crystal alignment agents, and it was confirmed to be a uniform solution.

    <Comparative Examples 1 to 5>    

A liquid crystal alignment agent (7) ~ was prepared in the same manner as in Example 1 except that each of the 12 mass% polyamic acid solutions (G) ~ (K) obtained in Synthesis Examples 7 ~ 11 was used. (11). No abnormal phenomenon such as turbidity or precipitation was found in any of these liquid crystal alignment agents, and it was confirmed to be a uniform solution.

    (Example 7)    

After the liquid crystal alignment agent (1) obtained in Example 1 was filtered using a 1.0 μm filter, the liquid crystal alignment agent (1) was spin-coated on a 30 mm × 40 mm ITO substrate. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation was 100 / cm ² of different anisotropy value 1.31,150mJ / cm ² of different anisotropy value 3.10,200mJ / cm ² of different tropism is 2.25. The irradiation amount of the above-mentioned ultraviolet rays having the highest anisotropy was 150 mJ / cm ² , and this was used as the irradiation conditions most suitable for the photo-alignment treatment.

    (Example 8)    

After the liquid crystal alignment agent (2) obtained in Example 2 was filtered using a 1.0 μm filter, it was spin-coated on a 30 mm × 40 mm ITO substrate. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the height of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation is 50mJ / cm ² of different anisotropy value 0.43,100mJ / cm ² of different anisotropy value 3.53,150mJ / cm ² of Time anisotropy value of 3.26. The irradiation amount of the above-mentioned ultraviolet rays having the highest anisotropy was 150 mJ / cm ² , and this was used as the irradiation conditions most suitable for the photo-alignment treatment.

    (Example 9)    

After the liquid crystal alignment agent (3) obtained in Example 3 was filtered using a 1.0 μm filter, it was spin-coated on a 30 mm × 40 mm ITO substrate. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the height of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 200mJ / cm ² of different anisotropy value 2.24,300mJ / cm ² of different anisotropy value 3.41,400mJ / cm ² of different tropism is 1.51. The irradiation amount of the above-mentioned ultraviolet rays having the highest anisotropy was 300 mJ / cm ² , and this was used as the irradiation conditions most suitable for the photo-alignment treatment.

    (Example 10)    

After the liquid crystal alignment agent (4) obtained in Example 4 was filtered using a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm × 40 mm. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the height of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of different anisotropy value 1.15,200mJ / cm ² of different anisotropy value 2.30,300mJ / cm ² of Time anisotropy value of 2.26. The irradiation amount of the above-mentioned ultraviolet rays having the highest anisotropy was 200 mJ / cm ² , and this was used as the irradiation conditions most suitable for the photo-alignment treatment.

    (Example 11)    

After the liquid crystal alignment agent (5) obtained in Example 5 was filtered using a 1.0 μm filter, the liquid crystal alignment agent (5) was spin-coated on a 30 mm × 40 mm ITO substrate. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the height of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of different anisotropy value 4.29,150mJ / cm ² of Time anisotropy value 5.23,200mJ / cm ² of different tropism is 3.00. The irradiation amount of the above-mentioned ultraviolet rays having the highest anisotropy was 150 mJ / cm ² , and this was used as the irradiation conditions most suitable for the photo-alignment treatment.

    (Example 12)    

After the liquid crystal alignment agent (6) obtained in Example 6 was filtered using a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm × 40 mm. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the height of the anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of Time anisotropy value 2.76,150mJ / cm ² of different anisotropy value 4.87,200mJ / cm ² of different tropism is 4.01. The irradiation amount of the above-mentioned ultraviolet rays having the highest anisotropy was 150 mJ / cm ² , and this was used as the irradiation conditions most suitable for the photo-alignment treatment.

    (Comparative Example 6)    

After the liquid crystal alignment agent (7) obtained in Comparative Example 1 was filtered using a 1.0 μm filter, it was spin-coated on a 30 mm × 40 mm ITO substrate. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of Time anisotropy value 2.02,200mJ / cm ² of different anisotropy value 2.87,300mJ / cm ² of different tropism is 2.51. When the anisotropy is maximum, the irradiation amount of the above-mentioned ultraviolet rays is 200 mJ / cm ² , and this is taken as the most suitable irradiation condition for the photo-alignment treatment.

    (Comparative Example 7)    

After the liquid crystal alignment agent (8) obtained in Comparative Example 2 was filtered using a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm × 40 mm. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 100mJ / cm ² of different anisotropy value 5.02,150mJ / cm ² of Time anisotropy value 7.37,200mJ / cm ² of different tropism is 6.40. When the anisotropy is maximum, the irradiation amount of the above-mentioned ultraviolet rays is 150 mJ / cm ² , and this is used as an irradiation condition most suitable for the photo-alignment treatment.

    (Comparative Example 8)    

After the liquid crystal alignment agent (9) obtained in Comparative Example 3 was filtered using a 1.0 μm filter, it was spin-coated on an ITO substrate of 30 mm × 40 mm. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation is 50mJ / cm ² of Time anisotropy value 4.11,100mJ / cm ² of different anisotropy value 5.78,150mJ / cm ² of different tropism is 4.55. When the anisotropy is maximum, the irradiation amount of the above-mentioned ultraviolet rays is 100 mJ / cm ² , and this is used as an irradiation condition most suitable for the photo-alignment treatment.

    (Comparative Example 9)    

After the liquid crystal alignment agent (10) obtained in Comparative Example 4 was filtered using a 1.0 μm filter, the liquid crystal alignment agent (10) was spin-coated on a 30 mm × 40 mm ITO substrate. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation 400mJ / cm ² of different anisotropy value 1.60,600mJ / cm ² of different anisotropy value 1.78,800mJ / cm ² of different tropism is 1.33. When the anisotropy is maximum, the irradiation amount of the above-mentioned ultraviolet rays is 600 mJ / cm ² , and this is used as an irradiation condition most suitable for the photo-alignment treatment.

    (Comparative Example 10)    

After the liquid crystal alignment agent (11) obtained in Comparative Example 5 was filtered using a 1.0 μm filter, the liquid crystal alignment agent (11) was spin-coated on an ITO substrate of 30 mm × 40 mm. After drying on a heating plate at 80 ° C for 2 minutes, baking was performed in a hot air circulation oven at 230 ° C for 14 minutes to form a coating film with a film thickness of 100 nm. The coating film surface was irradiated with ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 through a polarizing plate, and the magnitude of anisotropy with respect to the alignment direction of the obtained liquid crystal alignment film was measured. The amount of the ultraviolet irradiation is 50mJ / cm ² of Time anisotropy value 5.54,100mJ / cm ² of different anisotropy value 7.34,200mJ / cm ² of different tropism is 6.40. When the anisotropy is maximum, the irradiation amount of the above-mentioned ultraviolet rays is 100 mJ / cm ² , and this is used as an irradiation condition most suitable for the photo-alignment treatment.

    (Example 13)    

The liquid crystal alignment agent (1) obtained in Example 1 was filtered with a 1.0 μm filter, and then applied to the prepared substrate with the electrode and a ITO film formed on the inner surface thereof by a spin coater to form a columnar gap having a height of 4 μm. Glass substrate. After drying on a hot plate at 80 ° C for 5 minutes, baking was performed in a hot air circulation oven at 230 ° C for 20 minutes to form a coating film with a film thickness of 100 nm. Ultraviolet rays with a wavelength of 254 nm linearly polarized at an extinction ratio of 26: 1 were irradiated to the coating film surface at 150 mJ / cm ² through a polarizing plate, and heated on a heating plate at 230 ° C. for 14 minutes to obtain a liquid crystal alignment film. The substrate. Taking the above two substrates as a group, a sealant was printed on the substrate, and another substrate was bonded so as to face the liquid crystal alignment film surface with an orientation direction of 0 °, and then the sealant was hardened to obtain an empty cell. Liquid crystal MLC-7026-100 (manufactured by Mok) was injected into the empty cell using a reduced pressure injection method, and then the injection port was sealed to obtain an FFS-driven liquid crystal cell. Subsequently, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour, and after being left for one night, the afterimage evaluation was performed using a long-term AC drive. The value of the angle Δ of the liquid crystal cell after long-term AC driving is 0.08 degrees. In addition, when the bright spots in the unit cell were observed, the number of bright spots was less than 10, which was good.

    (Example 14)    

After irradiating the liquid crystal alignment agent (1) obtained in Example 1 with polarized ultraviolet light, it was immersed in 2-propanol for 3 minutes, and then immersed in pure water for 1 minute. All other methods were the same as in Example 13. An FFS driven liquid crystal cell was obtained. This FFS-driven liquid crystal cell was subjected to an afterimage evaluation using a long-term AC driving method. The value of the angle Δ of the liquid crystal cell after long-term AC driving is 0.10 degrees. In addition, when the bright spots in the unit cell were observed, the number of bright spots was less than 10, which was good.

    (Examples 15 to 19)    

Except that the liquid crystal alignment agents (2) to (6) obtained in Examples 2 to 6 were used, each coating film having a film thickness of 100 nm was formed in the same manner as in Example 13. Except for the linearly polarized light having an extinction ratio of 26: 1 and a wavelength of 254 nm, ultraviolet rays are irradiated through the polarizing plates according to the exposure amounts (unit: mJ / cm ² ) described in Table 1 below. Example 13 uses the same method to prepare a substrate with a liquid crystal alignment film. Next, each FFS-driven liquid crystal cell is fabricated, and the residual image evaluation during long-term AC driving is performed. Table 1 shows the angle Δ value of each liquid crystal cell after long-term AC driving, and the results obtained by observing the bright spots in the cell. When the number of bright spots is less than 10, the mark is good, and when the number of bright spots is 10 or more, the mark is bad.

    (Comparative Examples 11 to 15)    

Except that the liquid crystal alignment agents (7) to (11) obtained in Comparative Examples 1 to 5 were used, respectively, each coating film having a film thickness of 100 nm was formed in the same manner as in Example 13. Ultraviolet rays with a wavelength of 254 nm of linearly polarized light having an extinction ratio of 26: 1 were irradiated through the polarizing plates according to the exposure amounts (unit: mJ / cm ² ) described in Table 1 below, and the rest of the coating films were based on The same method as in Example 13 was used to prepare a substrate with a liquid crystal alignment film. Next, each FFS-driven liquid crystal cell was fabricated, and a long-term AC-driven residual image evaluation was performed. Table 1 shows the angle Δ value of each liquid crystal cell after long-term AC driving and observation of the bright spots in the cell. When the number of bright spots is less than 10, the mark is good, and when the number of bright spots is 10 or more, the mark is bad.

    [Industrial availability]    

Even when the liquid crystal alignment agent of the present invention uses a negative type liquid crystal, it does not produce bright spots caused by the decomposition products generated by the liquid crystal alignment film generated during the photo alignment process, and is a liquid crystal with good afterimage characteristics. Alignment film. Therefore, the liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention has extremely low brightness caused by the decrease in contrast and the main cause, and can be reduced in the AC driving mechanism generated in the liquid crystal display element of the IPS driving method or FFS driving method. As a result of the residual image, a liquid crystal display element having an IPS driving method or an FFS driving method having excellent afterimage characteristics can be obtained. Therefore, it can be used for a liquid crystal display element which seeks high display quality.

Claims (12)

A liquid crystal alignment agent, comprising a polyimide precursor having a structural unit represented by the following formula (1) and the following formula (2), and a polyimide of the polyimide precursor At least one polymer (A) selected from the group of polymers; (In formulas (1) and (2), X ₁ and X ₂ each independently represent a tetravalent organic group, R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, A ₁ , A ₂ , A ₃ , and A ₄ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Z ₁ , Z ₂ , Z ₃ , and Z ₄ each independently represent a hydrogen atom, a halogen atom, and a carbon number 1 ~ 4 alkyl, n is an integer from 1 to 4).     For example, the liquid crystal alignment agent of claim 1, wherein the content ratio of the structural unit represented by the above formula (1) is 10 to 50 mol% relative to 1 mole of the full structural unit of the polymer (A). The content ratio of the structural unit indicated in (2) is 20 to 90 mol% relative to 1 mol of the total structural unit of the polymer (A).     For example, in the liquid crystal alignment agent of claim 1 or 2, in formula (1), formula (2), and formula (3), X ₁ , X ₂ and X _{3 are represented} by the following formulas (X1-1) to ( X1-9) at least one selected from the group formed by the structure represented by X1-9); (In formula (X1-1), R ₃ , R ₄ , R ₅ , and R ₆ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkyne Group, or phenyl, which may be the same or different). For example, the liquid crystal alignment agent according to claim 1 or 2, wherein the polymer (A) has a structural unit other than the formula (1) and the formula (2), which is a structural unit represented by the following formula (3); (In the formula (3), X ₃ each independently represents at least one selected from the group consisting of the structures represented by the formulae (X1-1) to (X1-9), and R ₃ is a hydrogen atom or a carbon number of 1 ~ 4 alkyl groups, Y ₁ is at least one selected from the group consisting of the structures represented by the following formulas [1d-1] to [1d-7]) (In formulas [1d-1] to [1d-7], D is a tert-butoxymethoxycarbonyl group, and n1 to n5 each independently represent an integer of 1 to 5).     For example, the liquid crystal alignment agent according to item 1 or 2, wherein the content ratio of the structural unit represented by formula (3) is 10 to 50 mol% relative to 1 mol of the total structural unit of the polymer (A).     For example, the liquid crystal alignment agent of item 1 or item 2, wherein, in formula (1), formula (2), and formula (3), X ₁ , X ₂ and X ₃ are represented by the above formula (X1-1) At least one selected from the group formed by the structure. For example, if the liquid crystal alignment agent of item 1 or item 2 is required, in formula (1), formula (2), and formula (3), X ₁ , X ₂ and X _{3 are represented} by the following formulas (X1-10) and (X1-11) at least one selected from the group formed by the structure represented by; For example, the liquid crystal alignment agent according to claim 1 or 2, wherein in the formula (1), the formula (2), and the formula (3), X ₁ , X _2, and X ₃ are the foregoing formula (X1-11).     A liquid crystal alignment film is characterized by being obtained by irradiating polarized ultraviolet rays on a film obtained by coating and baking the liquid crystal alignment agent according to any one of claims 1 to 8.         A liquid crystal alignment film, which is obtained by using an inkjet method using the liquid crystal alignment agent of claim 1 or 2.         A liquid crystal display element comprising the liquid crystal alignment film according to any one of claim 9 and claim 10.         The liquid crystal display element according to claim 11, wherein the liquid crystal is a negative type liquid crystal material.