KR20150001826A - Liquid-crystal alignment material for use in photo-alignment method, liquid-crystal alignment film, and liquid-crystal display element - Google Patents

Abstract

(X₁ 은 특정 구조를 갖는 4 가의 유기기이고, R₁ 은 수소 원자 또는 탄소수 1 ∼ 4 의 알킬기이다)A liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element are provided for obtaining a liquid crystal alignment film for a photo alignment method having good afterimage characteristics even when the substrate is cleaned with a cleaning liquid.
A liquid crystal aligning agent for a photo alignment method comprising a polyimide precursor represented by formula (1) and at least one polymer selected from an imidized polymer of the polyimide precursor and an organic solvent.

(X ₁ is a tetravalent organic group having a specific structure and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms)

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element for a photo alignment method,

The present invention relates to a liquid crystal aligning agent for producing a liquid crystal alignment film, a liquid crystal alignment film obtained from the liquid crystal aligning agent and a liquid crystal display element. More specifically, in place of the rubbing treatment, a liquid crystal aligning agent used for forming a liquid crystal alignment film capable of imparting a liquid crystal aligning ability by irradiation with polarized ultraviolet rays, a liquid crystal alignment film obtained from the liquid crystal aligning agent And a liquid crystal display element.

In a liquid crystal display element used for a liquid crystal television, a liquid crystal display, or the like, a liquid crystal alignment film for controlling the alignment state of the liquid crystal is usually formed in the element.

At present, according to a method most widely used in industry, this liquid crystal alignment film is formed by laminating the surface of a film made of polyamic acid and / or imidized polyimide formed on the electrode substrate with a cloth such as cotton, nylon, And rubbing it in one direction, so-called rubbing treatment.

The rubbing treatment of the film surface in the alignment process of the liquid crystal alignment film is an industrially useful method which is simple and excellent in productivity. However, there is a growing demand for high performance, high definition, and large size liquid crystal display devices, and there is a growing demand for scratches, oscillations, effects due to mechanical force and static electricity on the surface of the alignment film caused by rubbing treatment, Various problems are becoming clear.

As a method for replacing the rubbing treatment, there is known a photo alignment method in which a liquid crystal aligning ability is imparted by irradiating polarized ultraviolet rays. The liquid crystal alignment treatment by the photo alignment method has been proposed by using a photo-isomerization reaction, a photo-crosslinking reaction, or a photo-decomposition reaction (see Non-Patent Document 1).

In Patent Document 1, it has been proposed to use a polyimide film having an alicyclic structure such as a cyclobutane ring in the main chain for the photo alignment method. When used in a liquid crystal alignment film for photo-alignment using polyimide, its usefulness is expected in that it has higher heat resistance than the other.

Such an optical alignment method is advantageous in that it can be produced in a manufacturing process that is industrially easy as a rubbing-less alignment treatment method. In addition, the IPS alignment method is advantageous in that it can be manufactured by IPS driving method or FFS (field switching) , It is possible to improve the contrast and viewing angle characteristics of the liquid crystal display element compared to the liquid crystal alignment film obtained by the rubbing method by using the liquid crystal alignment film obtained by the above photo alignment method, And thus has attracted attention as a promising liquid crystal alignment treatment method.

In addition to the basic characteristics such as excellent liquid crystal alignability and electrical characteristics, the liquid crystal alignment film used in the IPS drive method or the FFS drive type liquid crystal display device is required to have long-term interchangeability It is necessary to suppress afterimage by driving.

However, the liquid crystal alignment film obtained by the photo alignment method has a problem that anisotropy with respect to the alignment direction of the polymer film is smaller than that caused by rubbing. If the anisotropy is small, sufficient liquid crystal alignability can not be obtained. In the case of using a liquid crystal display element, a problem such as a residual image occurs. On the other hand, as a method of increasing the anisotropy of the liquid crystal alignment film obtained by the photo alignment method, it has been proposed to remove the low molecular weight component produced by cutting the main chain of the polyimide by light irradiation after light irradiation 2).

Japanese Patent Application Laid-Open No. 9-297313 Japanese Laid-Open Patent Publication No. 2011-107266

 "Liquid crystal photo alignment layer" Kidowaki, Ichimura Functional material November, 1997 issue Vol.17 No.11 13-22 page

The manufacturing process of the liquid crystal device includes a process of cleaning the substrate on which the liquid crystal alignment film is formed. As the cleaning liquid used in this cleaning process, a cleaning liquid containing water or 2-propanol as a main component is used.

However, as a result of a study by the inventors of the present invention, it has been found that a liquid crystal for optical alignment method obtained by applying and firing a polyimide precursor comprising an alicyclic tetracarboxylic dianhydride and a derivative thereof and an aromatic diamine, It was found that the alignment film was markedly deteriorated by washing with a cleaning liquid containing an organic solvent such as water or 2-propanol as a main component. Specifically, it was found that the after-image was generated by the long-term AC drive by cleaning the obtained film.

An object of the present invention is to provide a liquid crystal aligning agent for a photo alignment method for obtaining a liquid crystal alignment film for a photo alignment method in which good afterimage characteristics can be obtained even when a liquid crystal alignment film is washed with a cleaning liquid containing water or 2-propanol as a main component, And a liquid crystal display element comprising the liquid crystal aligning agent.

In order to achieve the above object, the present inventors have conducted intensive studies and, as a result, have found that a polyimide precursor obtained from a tetracarboxylic acid dianhydride and a derivative thereof having a specific structure of an alicyclic structure and a diamine compound having a specific structure, It is possible to achieve the above object by means of a liquid crystal aligning agent for a photo alignment method which contains at least one kind of polymer selected from the group consisting of an imidized polymer of a polyimide precursor.

Thus, the present invention provides the following.

1. An optical alignment film characterized by containing a polymer containing at least one member selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (1) and an imidized polymer of the polyimide precursor and an organic solvent Liquid crystal aligning agent for legal purposes.

[Chemical Formula 1]

(In the formula (1), X ₁ is at least one kind selected from the group consisting of the structures represented by the following formulas (X1-1) to (X1-9), and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms to be.)

(2)

(Wherein R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group or a phenyl group And may be the same or different.)

2. The polyimide precursor of claim 1, wherein the polymer comprises at least one member selected from the group consisting of a polyimide precursor containing 60 mol% or more of the structural unit represented by the formula (1) Is the liquid crystal alignment agent for the photo alignment method described in the above item (1).

3. The liquid crystal aligning agent for a photo alignment method according to any one of 1 to 2 above, wherein X ₁ in the formula ( ₁ ) is a structure represented by the formula (X1-1).

4. The optical alignment method according to any one of 1 to 3 above, wherein X ₁ in the formula (1) is at least one selected from the group consisting of structures represented by the following formulas (X1-10) to (X1-11) Liquid crystal aligning agent for legal purposes.

(3)

5. A polyimide precursor having a structural unit represented by formula (1) or a liquid crystal aligning agent for a photo alignment method described in any one of 1 to 4 above, wherein the imidized polymer of the polyimide precursor has a weight average molecular weight of 5000 to 300000 .

6. The liquid crystal aligning agent for a photo alignment method according to any one of 1 to 4 above, wherein the content of the polymer is 1 wt% or more and 10 wt% or less.

7. A liquid crystal alignment film obtained by applying and firing a liquid crystal aligning agent for a photo alignment method according to any one of 1 to 6 above.

8. A liquid crystal alignment film obtained by coating and firing a liquid crystal aligning agent for a photo alignment method as described in any one of 1 to 6 above, and then irradiating linearly polarized ultraviolet rays and cleaning.

9. A liquid crystal display element comprising the liquid crystal alignment film according to 7 or 8 above.

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention can be obtained by irradiating polarized ultraviolet rays to impart anisotropy to the liquid crystal alignment film and then cleaning the liquid crystal alignment film with a cleaning liquid containing water or 2-propanol as a main component In the case of using a liquid crystal alignment film of a liquid crystal display element of the IPS drive method or the FFS drive method, the afterimage due to the long-term AC drive can be reduced.

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention exhibits good afterimage characteristics with low irradiation energy.

<Liquid Crystal Aligner>

The liquid crystal aligning agent of the present invention is characterized by containing at least one kind of polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (1) and an imidized polymer of the polyimide precursor and an organic solvent Of the liquid crystal aligning agent.

[Chemical Formula 4]

In the formula (1), R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. From the viewpoint of ease of imidization by heating, a hydrogen atom or a methyl group is particularly preferable.

In the formula (1), X ₁ is at least one selected from the group consisting of structures represented by the following formulas (X1-1) to (X1-9).

[Chemical Formula 5]

In the formula _{(X1-1), R 3, R} 4, R 5 and R ₆ are each independently a hydrogen atom, a halogen atom, an alkenyl group having 1 to 6 carbon atoms alkyl group, having 2 to 6 carbon atoms, an alkynyl group or a phenyl group , They may be the same or different. R ₃ , R ₄ , R ₅ and R ₆ are preferably a hydrogen atom, a halogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom or a methyl group, more preferably a group represented by the following formula X1-10) to (X1-11).

[Chemical Formula 6]

In the imidized polymer of the polyimide precursor and the polyimide precursor containing the structural unit represented by the formula (1), the proportion of the structural unit represented by the formula (1) is preferably 60 Mol% to 100 mol% is preferable. The higher the proportion of the structural unit represented by the above formula (1), the better the liquid crystal alignment film having a good liquid crystal alignability, and therefore it is more preferably 80 mol% to 100 mol%, still more preferably 90 mol% to 100 mol% .

The liquid crystal aligning agent of the present invention may be a polyimide precursor containing a structural unit represented by the following formula (2) and a polyimide precursor thereof in addition to the structural unit represented by the above formula (1).

(7)

In the formula (2), R ₁ has the same definition as R ₁ in the formula (1). X ₂ is a tetravalent organic group, and its structure is not particularly limited. Specific examples thereof include structures of the following formulas (X-9) to (X-42). From the viewpoint of availability of the compound, examples of the structure of X ₂ include X-17, X-25, X-26, X-27, X-28, X-32 and X-39. It is preferable to use tetracarboxylic acid dianhydride having an aromatic ring structure from the viewpoint of obtaining a liquid crystal alignment film which can alleviate the residual charge accumulated by the direct current voltage and X ₂ , X-27, X-28, X-32, X-35 or X-37 are more preferable.

[Chemical Formula 8]

[Chemical Formula 9]

[Chemical formula 10]

(11)

In the formula (2), Y ₂ is a divalent organic group and its structure is not particularly limited. Specific examples of Y ₂ include structures of the following formulas (Y-1) to (Y-86).

[Chemical Formula 12]

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

[Chemical Formula 18]

[Chemical Formula 19]

[Chemical Formula 20]

An improvement in liquid crystal alignability can be expected. Therefore, a structure having a high linearity is preferable as the structure of Y &lt; _{2 &} gt ;. Specific examples thereof are Y-74, Y-75, Y-76, Y-77 or Y-78.

In order to improve the solubility of the polyimide precursor and polyimide in the organic solvent, the structure of Y ₂ is preferably Y-8, Y-20, Y-21, Y-22, Y-28, Y -29, Y-30, Y-71, Y-72, Y-73 or Y-85 are more preferable.

<Production method of polyamic acid ester>

The polyamic acid ester used as the polyimide precursor used in the present invention can be synthesized by the following method (1), (2) or (3).

(1) Synthesis from polyamic acid

The polyamic acid ester can be synthesized by esterifying a polyamic acid obtained from a tetracarboxylic dianhydride and a diamine.

Concretely, the polyamic acid and the esterifying agent are reacted in the presence of an organic solvent at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably 1 to 4 hours .

The esterifying agent is preferably one which can be easily removed by purification. Examples of the esterifying agent include N, N-dimethylformamide dimethylacetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamide dineopentylbutyl acetal, N, N-dimethylformamide di-t-butyl acetal, 1-methyl-3-p-tolyltriazine, , 1-propyl-3-p-tolyltriazine, and 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride. The addition amount of the esterifying agent is preferably 2 to 6 molar equivalents relative to 1 mol of the repeating unit of the polyamic acid.

The solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or? -Butyrolactone in view of the solubility of the polymer, May be used. The concentration at the time of the synthesis is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that the precipitation of the polymer does not occur well and the high molecular weight material is easily obtained.

(2) Synthesis by reaction of tetracarboxylic acid diester dichloride with diamine

Polyamic acid esters can be synthesized from tetracarboxylic acid diester dichloride and diamines.

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

As the base, pyridine, triethylamine, 4-dimethylaminopyridine and the like can be used, but pyridine is preferred since the reaction proceeds mildly. The amount of the base to be added is preferably from 2 to 4 times the tetracarboxylic acid diester dichloride from the viewpoint of easy removal and high molecular weight.

The solvent used in the above reaction is preferably N-methyl-2-pyrrolidone or? -Butyrolactone in view of the solubility of the monomer and the polymer, and these solvents may be used alone or in combination of two or more. The concentration of the polymer at the time of the synthesis is preferably from 1 to 30 mass%, more preferably from 5 to 20 mass% from the viewpoint that the precipitation of the polymer does not occur well and the high molecular weight material is easily obtained. Further, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, the solvent used for the synthesis of the polyamic acid ester is preferably dehydrated as much as possible, and it is preferable to prevent the introduction of outside air in a nitrogen atmosphere.

(3) Synthesis of polyamic acid ester from tetracarboxylic acid diester and diamine

The polyamic acid ester can be synthesized by polycondensation of a tetracarboxylic acid diester and a diamine.

Specifically, the tetracarboxylic acid diester and diamine are reacted in the presence of a condensing agent, a base and an organic solvent at 0 ° C to 150 ° C, preferably 0 ° C to 100 ° C for 30 minutes to 24 hours, For 15 hours.

Examples of the condensing agent include triphenylphosphine, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N'- carbonyldiimidazole, dimethoxy- (Benzotriazol-1-yl) -N, N, N ', N'-tetramethyluronium tetrafluoroborate, O- (benzotriazol- (2,3-dihydro-2-thioxo-3-benzoxazolyl) diphenylphosphonate, etc. can be used. have. The amount of the condensing agent to be added is preferably 2 to 3 times the mole of the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base to be added is an amount that is easy to remove and is preferably 2 to 4 times the amount of the diamine component from the viewpoint of easily obtaining a high molecular weight material.

In addition, in the above reaction, the reaction proceeds efficiently by adding Lewis acid as an additive. As the Lewis acid, lithium halides such as lithium chloride and lithium bromide are preferable. The addition amount of the Lewis acid is preferably from 0 to 1.0 times the amount of the diamine component.

Among the methods for synthesizing the above three polyamic acid esters, the synthesis method of the above (1) or (2) is particularly preferable because a high molecular weight polyamic acid ester can be obtained.

The solution of the polyamic acid ester obtained as described above can be precipitated by injecting it into a poor solvent while stirring well. After several times of precipitation and washing with a poor solvent, the purified polyamic acid ester powder can be obtained at room temperature or by heating and drying. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Production method of polyamic acid>

Polyamic acid, which is a polyimide precursor used in the present invention, can be synthesized by the following method.

Specifically, the tetracarboxylic acid dianhydride and the diamine are reacted in the presence of an organic solvent at -20 ° C to 150 ° C, preferably 0 ° C to 50 ° C for 30 minutes to 24 hours, preferably 1 to 12 hours Can be synthesized.

The organic solvent used in the above reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or gamma -butyrolactone in view of the solubility of the monomer and the polymer, Or more may be mixed and used. The concentration of the polymer is preferably from 1 to 30 mass%, more preferably from 5 to 20 mass%, from the viewpoint that the precipitation of the polymer does not occur well and the high molecular weight material is easily obtained.

The polyamic acid thus obtained can be recovered by precipitating a polymer by injecting the reaction solution into a poor solvent while stirring well. Further, the precipitation is repeated several times, washed with a poor solvent, and then dried at room temperature or heated to obtain a purified polyamic acid powder. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Production method of polyimide>

The polyimide used in the present invention can be prepared by imidizing the polyamic acid ester or polyamic acid. In the case of producing a polyimide from a polyamic acid ester, chemical imidization by adding a basic catalyst to the polyamic acid solution obtained by dissolving the polyamic acid ester solution or the polyamic acid ester resin powder in an organic solvent is simple. The chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is not lowered in the process of imidization.

The chemical imidization can be carried out by stirring the polyamic acid ester to be imidized in the presence of a basic catalyst in an organic solvent. As the organic solvent, a solvent used in the polymerization reaction described above may be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, triethylamine is preferred because it has sufficient basicity to proceed the reaction.

The temperature at which the imidization reaction is carried out is -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 moles, preferably 2 to 20 moles, of the amic ester group. The imidization rate of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time. Since the added catalyst remains in the solution after the imidization reaction, it is preferable to recover the imidized polymer obtained by means described below and redissolve it with an organic solvent to obtain the liquid crystal aligning agent of the present invention .

In the case of producing a polyimide from polyamic acid, chemical imidization by adding a catalyst to a solution of the polyamic acid obtained in the reaction of the diamine component and the tetracarboxylic dianhydride is simple. The chemical imidization is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer is not lowered in the process of imidization.

The chemical 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 polymerization reaction described above may be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, and the like. Among them, pyridine is preferred because it has a basicity suitable for proceeding the reaction. As the acid anhydride, acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like can be given. Among them, acetic anhydride is preferable because the purification after completion of the reaction becomes easy.

The temperature at which the imidization reaction is carried out is -20 ° C to 140 ° C, preferably 0 ° C to 100 ° C, and the reaction time can be 1 to 100 hours. The amount of the basic catalyst is 0.5 to 30 molar times, preferably 2 to 20 molar times, and the amount of the acid anhydride is 1 to 50 molar times, preferably 3 to 30 molar times the amount of the amylic acid. The imidization rate of the resulting polymer can be controlled by adjusting the amount of catalyst, temperature, and reaction time.

The imidized polymer obtained by the means described below is recovered and redissolved in an organic solvent since the added catalyst remains in the solution after the imidation reaction of the polyamic acid ester or polyamic acid, It is preferable to use an orientation agent.

The solution of the polyimide obtained as described above can be precipitated by pouring into a poor solvent while stirring well. After several times of precipitation and washing with a poor solvent, the purified polyamic acid ester powder can be obtained at room temperature or by heating and drying.

Examples of the poor solvent include, but are not limited to, methanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene and benzene.

<Liquid Crystal Aligner>

The liquid crystal aligning agent used in the present invention has a form of a solution in which a polymer having a specific structure is dissolved in an organic solvent. The molecular weight of the polyimide precursor having the structural unit represented by the formula (1) and the at least one polymer selected from the imidized polymer of the polyimide precursor is preferably from 2,000 to 500,000, more preferably from 2,000 to 500,000, 5,000 to 300,000, and 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 of the liquid crystal aligning agent used in the present invention can be appropriately changed according to the setting of the thickness of the coating film to be formed. It is preferably 1% by mass or more from the viewpoint of forming a uniform and defect- But is preferably 10% by weight or less in terms of storage stability.

The organic solvent contained in the liquid crystal aligning agent used in the present invention is not particularly limited as long as the polymer having a specific structure is uniformly dissolved. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl- , N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone,? -Butyrolactone, 1,3-dimethyl- imidazolidinone, N, N-dimethylpropanamide, and the like. These may be used alone or in combination of two or more. In addition, even if the solvent can not solubilize the polymer uniformly, it may be mixed with the organic solvent as long as the solvent does not precipitate the polymer.

The liquid crystal aligning agent used in the present invention may contain a solvent for improving the uniformity of the coating film when the liquid crystal aligning agent is applied to the substrate, in addition to the organic solvent for dissolving the polymer having the specific structure. Such a solvent generally uses a solvent having a lower surface tension than the organic solvent. Specific examples thereof include ethylcellosolve, butylcellosolve, ethylcarbitol, butylcarbitol, ethylcarbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy- 2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether- Propanol, lactic acid methyl ester, lactic acid ethyl ester, lactic acid n-propyl ester, lactic acid n-butyl ester, lactic acid, isoamyl acetate, Esters and the like. These solvents may be used in combination of two or more.

The liquid crystal aligning agent of the present invention may contain other than the polymer described in the present invention and a dielectric or conductive material for changing electrical characteristics such as dielectric constant and conductivity of the liquid crystal alignment film, , A silane coupling agent for improving the adhesion between the liquid crystal alignment film and the substrate, a crosslinkable compound for increasing the hardness and density of the film when the film is used as a liquid crystal alignment film, and a polyimide precursor An imidization promoter for the purpose of efficiently promoting the reaction of the initiator.

&Lt; Production method of liquid crystal alignment film &

The liquid crystal alignment film of the present invention is characterized by comprising a step of applying a liquid crystal aligning agent to a substrate and baking, a step of irradiating the obtained film with polarized ultraviolet rays, a step of washing the film irradiated with ultraviolet rays with a cleaning liquid containing water or 2-propanol as a main component The liquid crystal alignment layer is preferably formed by a process for producing a liquid crystal alignment layer.

(1) a step of applying a liquid crystal aligning agent to a substrate and baking

The liquid crystal aligning agent thus obtained is applied to a substrate, followed by drying and firing, to obtain a film in which the polyimide film or the polyimide precursor is imidized.

The substrate to which the liquid crystal aligning agent used in the present invention is applied is not particularly limited as long as it is a substrate having high transparency. A glass substrate, a silicon nitride substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate, It is preferable to use a substrate on which an ITO electrode or the like is formed from the viewpoint of process simplification. Further, in a reflection type liquid crystal display element, an opaque material such as a silicon wafer can be used only for a substrate on one side. In this case, a material for reflecting light such as aluminum can also be used as the electrode in this case. Examples of the application method of the liquid crystal aligning agent used in the present invention include a spin coating method, a printing method, and an ink jet method.

The drying and firing steps after the application of the liquid crystal aligning agent to be used in the present invention can be performed at any temperature and time. Usually, it is dried at 50 to 120 ° C for 1 to 10 minutes to sufficiently remove the contained organic solvent, and then baked at 150 to 300 ° C for 5 to 120 minutes. The thickness of the coated film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may deteriorate. Therefore, it is 5 to 300 nm, preferably 10 to 200 nm.

(2) a step of irradiating the obtained film with polarized ultraviolet rays

Anisotropy is imparted to the film obtained in the method (1) by irradiating polarized ultraviolet rays (hereinafter, also referred to as photo-alignment treatment).

The higher the extinction ratio of the polarized ultraviolet ray is, the higher anisotropy can be given, which is preferable. Specifically, the extinction ratio of linearly polarized ultraviolet rays is preferably 10: 1 or more, more preferably 20: 1 or more.

As a specific example of the photo alignment treatment, there is a method of irradiating linearly polarized ultraviolet rays to the surface of the above coating film and, if necessary, further heating treatment at a temperature of 150 to 250 ° C to give liquid crystal aligning ability . As the wavelength of the ultraviolet rays, ultraviolet rays having a wavelength of 100 nm to 400 nm are preferable, and those having a wavelength of 200 nm to 400 nm are particularly preferable.

The irradiation dose of the radiation is preferably in the range of 1 to 10,000 mJ / cm 2, and particularly preferably in the range of 100 to 5,000 mJ / cm 2.

(3) a step of washing a film irradiated with ultraviolet rays

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention is characterized by exhibiting good properties as a liquid crystal alignment film by washing with water or a cleaning liquid containing 2-propanol as a main component. Since 2-propanol easily dissolves organic substances in the film than water, a cleaning liquid containing 2-propanol is more preferable as a cleaning liquid for the liquid crystal alignment film of the present invention.

As a cleaning method of the liquid crystal alignment film, a treatment in which the film and the liquid are sufficiently in contact with each other, such as an immersion treatment, a spray (spray) treatment, etc., is preferable. Among them, a method of immersing the film in the cleaning liquid, preferably for 10 seconds to 1 hour, more preferably for 1 minute to 30 minutes is preferable. The contact treatment may be carried out at room temperature, but is preferably carried out at 10 to 80 占 폚, more preferably at 20 to 50 占 폚. It is also possible to implement means for increasing the contact of ultrasonic waves or the like as necessary.

After the contact treatment, rinsing (rinsing) with a low-boiling solvent such as water, 2-propanol, or acetone, or drying may be performed for the purpose of removing the used organic solvent. The drying temperature is preferably 80 to 250 占 폚, more preferably 80 to 150 占 폚.

<Liquid crystal display element>

The liquid crystal display element of the present invention is characterized by comprising a liquid crystal alignment film obtained by the above-described method for producing a liquid crystal alignment film.

The liquid crystal display element of the present invention can be obtained by obtaining a substrate on which a liquid crystal alignment film is adhered by the method of manufacturing the liquid crystal alignment film from the liquid crystal alignment treatment agent described in the present invention by the above technique and then producing a liquid crystal cell by a known method, Thereby forming a liquid crystal display element.

As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. Further, the liquid crystal display element may be an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is formed in each pixel portion constituting the image display.

First, a transparent glass substrate is prepared, a common electrode is formed on one substrate, and a segment electrode is formed on the other substrate. These electrodes can be, for example, ITO electrodes and are patterned so as to perform desired image display. Subsequently, an insulating film is formed on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a film made of SiO ₂ -TiO ₂ formed by a sol-gel method.

Next, the liquid crystal alignment film of this embodiment is formed on each substrate. Next, the other substrate is superimposed on one of the substrates so that the orientation film surfaces of the other substrates face each other, and the periphery is adhered to the seal material. In order to control the substrate gap, a spacer is normally mixed in the sealing material. It is also preferable that a spacer for controlling the gap between the substrates is scattered on the in-plane portion on which the sealing material is not formed. In the part of the sealing material, an opening for filling the liquid crystal from the outside is formed.

Next, the liquid crystal material is injected into the space surrounded by the two substrates and the sealing material through the opening formed in the sealing material. Thereafter, this opening is sealed with an adhesive. A vacuum injection method may be used for the injection, or a method using capillary phenomenon in the atmosphere may be used. Next, the polarizing plate is installed. Specifically, a pair of polarizers is attached to a surface of the two substrates opposite to the liquid crystal layer. Through the above steps, the liquid crystal display element of the present invention is obtained. Since this liquid crystal display element uses the liquid crystal alignment film of the present invention as the liquid crystal alignment film, it has excellent afterimage characteristics, and can be preferably used for a liquid crystal television having a large screen and a high definition.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. The abbreviations of the compounds used in the present examples and comparative examples and the measurement methods of the respective properties are as follows.

NMP: N-methyl-2-pyrrolidone

BCS: butyl cellosolve

DA-2: The following formula (DA-2)

DA-3: The following formula (DA-3)

DAH-1: The following formula (DAH-1)

Additive A: N -? - (9-Fluorenylmethoxycarbonyl) -N-t-butoxycarbonyl-L-histidine

[Chemical Formula 21]

[Viscosity]

In the synthesis examples, the viscosity of the polyimide precursor solution was 1.1 ml, a cone rotor TE-1 (1 DEG 34 ', R24), and a temperature of 25 DEG C using a E-type viscometer TVE-22H Respectively.

[Molecular Weight]

The molecular weight of the polyimide precursor and its imidized polymer was measured by a GPC (room temperature gel permeation chromatography) apparatus, and the number average molecular weight (hereinafter also referred to as Mn) and the weight average molecular weight Hereinafter, also referred to as Mw).

GPC apparatus: manufactured by Shodex Corp. (GPC-101)

Column: manufactured by Shodex Co., Ltd. (serial of KD803, KD805)

Column temperature: 50 ° C

Eluent: N, N- dimethylformamide (lithium bromide as an additive-hydrate (LiBr · H ₂ O) is 30 m㏖ / ℓ, phosphoric acid anhydrous crystal (o- phosphoric acid) is 30 m㏖ / ℓ, tetrahydrofuran ( THF) 10 ml / l)

Flow rate: 1.0 ml / min

Standard sample for preparing a calibration curve: TSK standard polyethylene oxide (weight average molecular weight (Mw) of about 900,000, 150,000, 100,000 and 30,000) manufactured by Tosoh Corporation and polyethylene glycol (peak top molecular weight (Mp) of about 12,000 and 4,000 , 1,000). In order to avoid overlapping of the peaks, two samples of samples mixed with four types of 900,000, 100,000, 12,000 and 1,000, and three samples of 150,000, 30,000 and 4,000 were separately measured.

[Production of liquid crystal cell]

Thereby manufacturing a liquid crystal cell having a structure of Fringe Field Switching (FFS) mode liquid crystal display element.

Initially, a substrate with an electrode attached thereto was prepared. The substrate is a glass substrate having a size of 30 mm x 50 mm and a thickness of 0.7 mm. On the substrate, an ITO electrode having a common print pattern, which constitutes the counter electrode as the first layer, is formed. On the first-layer counter electrode, a SiN (silicon nitride) film formed by a CVD method is formed as a second layer.

The film thickness of the second SiN film is 500 nm and functions as an interlayer insulating film. On the second-layer SiN film, a comb-like pixel electrode formed by patterning the ITO film as the third layer is disposed, and two pixels, i.e., a first pixel and a second pixel, are formed. The size of each pixel is 10 mm in length and 5 mm in width. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer.

The third-layer pixel electrode has a comb-like shape formed by arranging a plurality of elongated electrode elements having a bent central portion. The width of each electrode element in the width direction is 3 占 퐉, and the interval between the electrode elements is 6 占 퐉. Since the pixel electrode forming each pixel is constituted by arranging a plurality of bent and elongated electrode elements at the center portion, the shape of each pixel is not a rectangle shape but is bent at the center portion like the electrode element, It has a shape similar to a bold letter. Each pixel has a first region which is an upper side of the bent portion and a second region which is a lower side, the upper side being divided into upper and lower portions with the central bent portion as a boundary.

When the first region and the second region of each pixel are compared with each other, the formation direction of the electrode elements of the pixel electrodes constituting the first region and the second region is different. In other words, when the rubbing direction of a liquid crystal alignment film to be described later is taken as a reference, the electrode elements of the pixel electrodes are formed so as to form an angle of +10 degrees (clockwise) in the first region of the pixel, The element is formed so as to form an angle (clockwise direction) of -10 degrees. That is, in the first region and the second region of each pixel, the direction of the rotation operation (inflation / switching) of the liquid crystal induced by the application of the voltage between the pixel electrode and the counter electrode is opposite to each other Consists of.

Next, after filtering the resultant liquid crystal aligning agent with a filter of 1.0 占 퐉, a glass substrate having a prepared columnar spacer with a height of 4 占 퐉 in which an ITO film was formed on the backside of the substrate and the prepared electrode was coated with a spin coat Respectively. Dried on a hot plate at 80 DEG C for 5 minutes and then fired in a hot air circulating oven at 230 DEG C for 20 minutes to form a coating film having a film thickness of 100 nm. This coated film surface was irradiated with ultraviolet rays having a wavelength of 254 nm and linearly polarized at an extinction ratio of 10: 1 or more through a polarizing plate to obtain a substrate having a liquid crystal alignment film attached thereto.

A pair of the above-mentioned two substrates was set, a sealing agent was printed on the substrate, and another substrate was bonded to the liquid crystal alignment film face so that the alignment direction was 0 ° so that the sealant was cured, . A liquid crystal MLC-2041 (manufactured by Merck Co.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. Thereafter, the obtained liquid crystal cell was heated at 110 DEG C for 1 hour, left for one night, and used for evaluation.

(After-image evaluation by long-term AC drive)

A liquid crystal cell having the same structure as the liquid crystal cell used for the after-image evaluation was prepared.

Using this liquid crystal cell, an AC voltage of ± 5 V was applied for 200 hours at a frequency of 60 Hz under a constant temperature environment of 60 ° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and left at room temperature for one day.

After leaving the liquid crystal cell, the liquid crystal cell was placed between two polarizing plates arranged so that the polarization axis thereof was orthogonal to each other, and the backlight was turned on in a voltage unapplied state, and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of the transmitted light was minimized. The angle of rotation when the liquid crystal cell was rotated from the angle at which the second area of the first pixel was darkest to the angle at which the first area became darkest was calculated as an angle DELTA. Similarly, in the second pixel, the second region and the first region are compared to calculate the same angle (?). The average value of the angle? Between the first pixel and the second pixel was calculated as the angle? Of the liquid crystal cell.

[Measurement of imidization rate]

The imidization rate of the polyimide in the synthesis example was measured as follows. (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture (0.53 ml)) was placed in an NMR sample tube (NMR sampling tube standard, φ5 , And completely dissolved by applying ultrasonic waves. This solution was subjected to proton NMR measurement at 500 MHz using an NMR meter (JNW-ECA500) (manufactured by Nippon Denshoku).

The proton derived from the structure in which the imidization ratio does not change before and after the imidization is defined as the reference proton and the proton peak integrated value derived from the NH group of the amide acid, which is shown in the vicinity of 9.5 ppm to 10.0 ppm, Was obtained by the following equation.

Imidization ratio (%) = (1 -? X / y) x 100

In the above formula, x is the proton peak integrated value derived from the NH group of the amide acid, y is the peak integrated value of the reference proton, and? Is the NH of the amide acid in the case of the polyamic acid (imidation rate is 0% The ratio of the number of reference protons to one protopertone.

(Synthesis Example 1)

4.89 g (20.02 mmol) of 1,2-bis (4-aminophenoxy) ethane was added to a 100 ml four-necked flask equipped with a stirrer and a nitrogen introduction tube, 69.75 g of NMP was added, And dissolved by stirring. While this diamine solution was stirred, 3.72 g (18.97 mmol) of 1,2,3,4-cyclobutane tetracarboxylic dianhydride was added, NMP was further added so that the solid content concentration became 10 mass% Followed by stirring for 24 hours to obtain a solution of polyamic acid (PAA-1). The viscosity of this polyamic acid solution at 25 캜 was 143 mPa.. The molecular weight of this polyamic acid was Mn = 12777 and Mw = 29720.

(Synthesis Example 2)

110.47 g (452 mmol) of 1,2-bis (4-aminophenoxy) ethane and 18.94 g (79.5 mmol) of DA-2 were taken in a 2000 ml four- necked flask equipped with a stirrer and a nitrogen- And 1587 g of NMP were added and dissolved by stirring while nitrogen was being supplied. 111.18 g (496 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride was added while stirring the diamine solution, and NMP And the mixture was stirred at 40 ° C for 20 hours to obtain a solution of polyamic acid (PAA-2). The viscosity of the polyamic acid solution at 25 캜 was 183 mPa.. The molecular weight of this polyamic acid was Mn = 12356 and Mw = 25544.

(Synthesis Example 3)

In a 3000 ml four-necked flask equipped with a stirrer and a nitrogen-introducing tube, 950 g of the obtained polyamic acid solution (PAA-2) was added, 678 g of NMP was added, and the mixture was stirred for 30 minutes. 77.11 g of acetic anhydride and 19.92 g of pyridine were added to the obtained polyamic acid solution, and the mixture was heated at 60 占 폚 for 3 hours to perform chemical imidization. The resulting reaction solution was poured into 6600 ml of methanol while stirring. The precipitated precipitate was collected by filtration, washed with 6600 ml of methanol three times, and then washed twice with 2000 ml of methanol. The resin powder thus obtained was dried at 60 DEG C for 12 hours to obtain a polyimide resin powder.

The imidization ratio of the polyimide resin powder was 75%, and the molecular weight was Mn = 8156 and Mw = 17408.

20.69 g of the obtained polyimide resin powder was taken in a 200 ml Erlenmeyer flask equipped with a stirrer and 151.71 g of NMP was added and dissolved by stirring at 40 DEG C for 24 hours to obtain a polyimide solution (PI-1).

(Synthesis Example 4)

4.20 g (17.19 mmol) of 1,2-bis (4-aminophenoxy) ethane and 7.70 g (25.81 mmol) of DA-3 were taken in a 200-ml four-necked flask equipped with a stirrer and a nitrogen- , 158 g of NMP was added, and dissolved with stirring while nitrogen was supplied. 12.02 g (40.85 mmol) of DAH-1 was added while stirring the diamine solution, NMP was further added so that the solid content concentration became 12 mass%, and the mixture was stirred at room temperature for 24 hours to obtain a solution of polyamic acid (PAA-6) . The viscosity of this polyamic acid solution at a temperature of 25 캜 was 390 mPa..

(Synthesis Example 5)

8.81 g (44.0 mmol) of 4,4'-diaminodiphenylethane and 19.69 g (65.99 mmol) of DA-3 were placed in a 500 ml four-necked flask equipped with a stirrer and a nitrogen- 146 g was added, and dissolved with stirring while nitrogen was being supplied. To this diamine solution, 6.54 g (33.0 mmol) of 1,2,3,4-butanetetracarboxylic dianhydride was added, NMP was further added so that the solid content concentration became 15 mass%, and the mixture was stirred at room temperature for 2 hours Lt; / RTI &gt;

Next, 146 g of NMP was added, 22.01 g (74.81 mmol) of DAH-1 was added, NMP was further added so that the solid concentration became 12 mass%, and the mixture was stirred at room temperature for 24 hours to obtain polyamic acid (PAA- 7) was obtained. The viscosity of this polyamic acid solution at a temperature of 25 캜 was 399 mPa s.

(Synthesis Example 6)

In a 1000 ml four-necked flask equipped with a stirrer and a nitrogen-introducing tube, 59.75 g (200 mmol) of DA-3 was taken, 284 g of NMP was added and dissolved with stirring while nitrogen was being supplied. 11.89 g (60.01 mmol) of 1,2,3,4-butanetetracarboxylic dianhydride was added while stirring the diamine solution, NMP was further added thereto so as to have a solid content concentration of 15 mass%, and the mixture was stirred at room temperature for 2 hours Lt; / RTI &gt;

Next, 284 g of NMP was added, 39.43 g (134 mmol) of DAH-1 was added, NMP was further added so that the solid content concentration became 12 mass%, and the mixture was stirred at room temperature for 24 hours to obtain polyamic acid (PAA- 8) was obtained. The viscosity of this polyamic acid solution at 25 캜 was 405 mPa..

(Synthesis Example 7)

63.76 g (320 mmol) of 4,4'-diaminodiphenylamine and 12.17 g (79.99 mmol) of 3,5-diaminobenzoic acid were placed in a 2000 ml four-necked flask equipped with a stirrer and a nitrogen- 1094 g of NMP was added, and dissolved with stirring while nitrogen was being supplied. While stirring the diamine solution, 112.59 g (383 mmol) of DAH-1 was added and NMP was further added so that the solid content concentration became 12 mass%. The mixture was stirred at room temperature for 24 hours to obtain a solution of polyamic acid (PAA-9) Solution. The viscosity of this polyamic acid solution at a temperature of 25 캜 was 384 mPa..

(Synthesis Example 8)

In a 2000 ml four-necked flask equipped with a stirrer and a nitrogen-introducing tube, 119.35 g (400 mmol) of DA-3 was added, 1536 g of NMP was added, and dissolved with stirring while nitrogen was being supplied. While stirring the diamine solution, 39.43 g (386 mmol) of DAH-1 was added, NMP was further added so that the solid concentration became 12 mass%, and the mixture was stirred at room temperature for 24 hours to obtain a solution of polyamic acid (PAA-10) Solution. The viscosity of this polyamic acid solution at a temperature of 25 캜 was 372 mPa..

(Comparative Synthesis Example 1)

4.25 g (20.02 mmol) of 4,4'-diamino-1,2-diphenylethane was added to a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 70.85 g of NMP was added, Followed by stirring and dissolving. While stirring the diamine solution, 3.82 g (19.48 mmol) of 1,2,3,4-cyclobutane tetracarboxylic dianhydride was added, NMP was further added so that the solid concentration became 10 mass%, and the mixture was stirred at room temperature Followed by stirring for 24 hours to obtain a solution of polyamic acid (PAA-3). The viscosity of the polyamic acid solution at 25 캜 was 156 mPa.. The molecular weight of this polyamic acid was Mn = 13966 and Mw = 33163.

(Comparative Synthesis Example 2)

5.17 g (20.01 mmol) of 1,3-bis (4-aminophenoxy) propane was added to a 100 ml four-necked flask equipped with a stirrer and a nitrogen introduction tube, 72.03 g of NMP was added, And dissolved by stirring. While this diamine solution was stirred, 3.79 g (19.33 mmol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and NMP was further added so that the solid content concentration became 10 mass% And stirred for 24 hours to obtain a solution of polyamic acid (PAA-4). The viscosity of the polyamic acid solution at 25 캜 was 162 mPa.. The molecular weight of the polyamic acid was Mn = 25902 and Mw = 40413.

(Comparative Synthesis Example 3)

In a 3000 ml four-necked flask equipped with a stirrer and a nitrogen-introducing tube, 1378 g of NMP was added, and 98.05 g (0.502 mol) of 1,2,3,4-cyclobutane tetracarboxylic dianhydride was added. While stirring the slurry of the tetracarboxylic dianhydride, 52.18 g (0.483 mol) of p-phenylenediamine was added, and further NMP was added so that the solid content concentration became 8 mass%. The mixture was stirred at room temperature for 24 hours, (PAA-5) was obtained. The viscosity of this polyamic acid solution at 25 캜 was 182 mPa.. The molecular weight of this polyamic acid was Mn = 18712 and Mw = 41702.

(Example 1)

12.00 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was put into a 20 ml sample tube containing the stirrer, 4.03 g of NMP and 4.00 g of BCS were added and stirred for 30 minutes by a magnetic stirrer to obtain a liquid crystal aligning agent (A-1).

(Comparative Example 1)

12.06 g of the polyamic acid solution (PAA-3) obtained in Comparative Synthesis Example 1 was placed in a 20 ml sample tube equipped with a stirrer, 4.09 g of NMP and 4.03 g of BCS were added, and the mixture was stirred with a magnetic stirrer for 30 minutes, (B-1) was obtained.

(Comparative Example 2)

12.06 g of the polyamic acid solution (PAA-4) obtained in Comparative Synthesis Example 2, 4.02 g of NMP and 4.13 g of BCS were added to a 20-ml sample tube equipped with a stirrer, stirred with a magnetic stirrer for 30 minutes, (B-2) was obtained.

(Comparative Example 3)

5.02 g of the polyamic acid solution (PAA-5) obtained in Comparative Synthesis Example 3, 3.00 g of NMP and 2.00 g of BCS were added to a 20 ml sample tube equipped with a stirrer, and the mixture was stirred with a magnetic stirrer for 30 minutes, (B-3) was obtained.

(Example 2)

The liquid crystal aligning agent (A-1) obtained in Example 1 was filtered through a filter having a size of 1.0 mu m, and then a glass substrate having a columnar spacer having a height of 4 mu m And applied by spin coat application. Dried on a hot plate at 80 DEG C for 5 minutes and then fired in a hot air circulating oven at 230 DEG C for 20 minutes to form a coating film having a film thickness of 100 nm. This coated film surface was irradiated with ultraviolet rays having a wavelength of 254 nm and a linear polarization of 26: 1 at an extinction ratio of 1.0 J / cm2 through a polarizing plate.

Subsequently, the substrate was immersed in 2-propanol, ultrasonically cleaned for 3 minutes, and then dried in a hot-air circulating oven at 80 DEG C for 5 minutes to obtain a substrate having a liquid crystal alignment film attached thereto. A pair of the above-mentioned two substrates was set, a sealing agent was printed on the substrate, and another substrate was bonded to the liquid crystal alignment film face so that the alignment direction was 0 ° so that the sealant was cured, . A liquid crystal MLC-2041 (manufactured by Merck Co.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. Thereafter, the resulting liquid crystal cell was heated at 110 DEG C for 1 hour, left standing overnight, and residual image was evaluated by long-term AC drive. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.57 degrees.

(Example 3)

An FFS-driven liquid crystal cell was fabricated in the same manner as in Example 2 except that the substrate with the orientation film was washed with water. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.61 degrees.

(Comparative Example 4)

An FFS-driven liquid crystal cell was produced in the same manner as in Example 2 except that the liquid crystal aligning agent (B-1) obtained in Comparative Example 1 was used. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.74 degrees.

(Comparative Example 5)

An FFS-driven liquid crystal cell was produced in the same manner as in Example 2 except that the liquid crystal aligning agent (B-2) obtained in Comparative Example 2 was used. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 1.28 degrees.

(Comparative Example 6)

An FFS-driven liquid crystal cell was produced in the same manner as in Example 3 except that the liquid crystal aligning agent (B-3) obtained in Comparative Example 3 was used and ultraviolet rays of 254 nm were irradiated at 1.5 J / cm 2 through a polarizing plate. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 1.02 degrees.

Liquid crystal aligning agent Cleaning liquid Afterimage (angle ()) due to long-term AC drive Example 2 (A-1) 2-propanol 0.57 DEG Example 3 (A-1) water 0.61 ° Comparative Example 4 (B-1) 2-propanol 0.74 ° Comparative Example 5 (B-2) 2-propanol 1.28 [deg.] Comparative Example 6 (B-3) 2-propanol 1.02 DEG

(Example 4)

10.73 g of the polyimide solution (PI-1) obtained in Synthesis Example 3 was placed in a 20 ml sample tube equipped with a stirrer, 5.27 g of NMP and 4.00 g of BCS were added and stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-2).

(Example 5)

5.56 g of the polyimide solution (PI-1) obtained in Synthetic Example 3 and 5.47 g of the polyamic acid solution (PAA-6) obtained in Synthetic Example 4 were taken in a 20 ml sample tube equipped with a stirrer, 4.97 g of NMP, And 0.19 g of Additive A were added and stirred for 30 minutes by a magnetic stirrer to obtain a liquid crystal aligning agent (A-3).

(Example 6)

5.54 g of the polyimide solution (PI-1) obtained in Synthetic Example 3 and 5.07 g of the polyamic acid solution (PAA-7) obtained in Synthetic Example 5 were taken in a 20 ml sample tube equipped with a stirrer, 5.38 g of NMP, And 0.19 g of Additive A were added and stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-4).

(Example 7)

5.52 g of the polyimide solution (PI-1) obtained in Synthesis Example 3 and 5.49 g of the polyamic acid solution (PAA-8) obtained in Synthesis Example 6 were introduced into a 20 ml sample tube into which an agitator was placed, 4.99 g of NMP, And 0.19 g of Additive A were added and stirred for 30 minutes by a magnetic stirrer to obtain a liquid crystal aligning agent (A-5).

(Example 8)

5.49 g of the polyimide solution (PI-1) obtained in Synthesis Example 3 and 5.22 g of the polyamic acid solution (PAA-9) obtained in Synthesis Example 7 were introduced into a 20 ml sample tube containing the stirrer, 5.28 g of NMP, And 0.19 g of Additive A were added and stirred for 30 minutes by a magnetic stirrer to obtain a liquid crystal aligning agent (A-6).

(Example 9)

5.54 g of the polyimide solution (PI-1) obtained in Synthesis Example 3 and 5.48 g of the polyamic acid solution (PAA-10) obtained in Synthetic Example 8 were taken in a 20 ml sample tube into which an agitator was placed, 4.98 g of NMP, And 0.19 g of Additive A were added and stirred for 30 minutes by a magnetic stirrer to obtain a liquid crystal aligning agent (A-7).

(Example 10)

The liquid crystal aligning agent (A-2) obtained in Example 4 was filtered with a filter having a pore diameter of 1.0 mu m, and then the prepared substrate on which the electrode was adhered and a glass having a columnar spacer having a height of 4 mu m And then applied to the substrate by spin coating. Dried on a hot plate at 80 DEG C for 5 minutes and then fired in a hot air circulating oven at 230 DEG C for 20 minutes to form a coating film having a film thickness of 100 nm. The surface of the coating film was irradiated with ultraviolet rays of 254 nm in a linearly polarized state at an extinction ratio of 26: 1 through a polarizing plate at 0.2 J / cm 2.

Subsequently, the substrate was immersed in 2-propanol and then dried in a hot-air circulating oven at 80 DEG C for 5 minutes to obtain a substrate having a liquid crystal alignment film attached thereto. A pair of the above-mentioned two substrates was set, a sealing agent was printed on the substrate, and another substrate was bonded to the liquid crystal alignment film face so that the alignment direction was 0 ° so that the sealant was cured, . A liquid crystal MLC-2041 (manufactured by Merck Co.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. Thereafter, the resulting liquid crystal cell was heated at 110 DEG C for 1 hour, left standing overnight, and residual image was evaluated by long-term AC drive. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.53 degrees.

(Example 11)

An FFS-driven liquid crystal cell was produced in the same manner as in Example 10 except that the liquid crystal aligning agent (A-3) obtained in Example 5 was used. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.51 degrees.

(Example 12)

An FFS-driven liquid crystal cell was produced in the same manner as in Example 10 except that the liquid crystal aligning agent (A-4) obtained in Example 6 was used. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.55 degrees.

(Example 13)

An FFS-driving liquid crystal cell was produced in the same manner as in Example 10 except that the liquid crystal aligning agent (A-5) obtained in Example 7 was used. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.50 degrees.

(Example 14)

An FFS-driven liquid crystal cell was produced in the same manner as in Example 10 except that the liquid crystal aligning agent (A-6) obtained in Example 8 was used. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.48 degrees.

(Example 15)

An FFS-driving liquid crystal cell was produced in the same manner as in Example 10 except that the liquid crystal aligning agent (A-7) obtained in Example 9 was used. The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.51 degrees.

(Example 16)

An FFS-driven liquid crystal cell was prepared in the same manner as in Example 10 except that the substrate having the alignment film was washed with a mixed solution of water and 2-propanol (water: 2-propanol = 50:50). The residual image evaluation by the long-term AC drive was performed on the FFS-driven liquid crystal cell. The value of the angle? Of this liquid crystal cell after the long-term AC drive was 0.40 degrees.

Liquid crystal aligning agent Cleaning liquid Afterimage (angle ()) due to long-term AC drive Example 10 (A-2) 2-propanol 0.53 DEG Example 11 (A-3) 2-propanol 0.51 Example 12 (A-4) 2-propanol 0.55 [deg.] Example 13 (A-5) 2-propanol 0.50 Example 14 (A-6) 2-propanol 0.48 DEG Example 15 (A-7) 2-propanol 0.51 Example 16 (A-8) Water: 2-propanol = 50: 50 0.40 [deg.]

Industrial availability

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention can reduce the afterimage due to the AC drive generated in the IPS drive method or the FFS drive type liquid crystal display device and can provide the IPS drive method or the FFS drive method A liquid crystal display element is obtained. Therefore, it is particularly useful as a liquid crystal display element of an IPS driving method, an FFS driving method, or a liquid crystal alignment film of a liquid crystal television.

The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2012-094759 filed on April 18, 2012 are hereby incorporated herein by reference as if fully set forth herein.

Claims (9)

A liquid crystal alignment for a photo alignment method characterized by containing at least one kind of polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (1) and an imidized polymer of the polyimide precursor and an organic solvent My.
[Chemical Formula 1]

(In the formula (1), X ₁ is at least one selected from the group consisting of the structures represented by the following formulas (X1-1) to (X1-9), and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms )
(2)

(Wherein R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group or a phenyl group , They may be the same or different.) The method according to claim 1,
Wherein the polymer is at least one selected from the group consisting of a polyimide precursor containing 60 mol% or more of the structural unit represented by the formula (1) relative to 1 mol of the total structural units and an imidization polymer of the polyimide precursor Of liquid crystal aligning agent. 3. The method according to claim 1 or 2,
Wherein the liquid crystal aligning agent is at least one selected from the group consisting of a structure represented by the formula (1) wherein X ₁ is a structure represented by the formula (X1-1). 4. The method according to any one of claims 1 to 3,
In the formula _(1), X 1 is the formula (X1-10) ~ The liquid crystal alignment of the photo-alignment beopyong is at least one selected from the group consisting of the structures represented by (X1-11).
(3)

5. The method according to any one of claims 1 to 4,
A liquid crystal aligning agent for a photo alignment method, wherein the polyimide precursor having the structural unit represented by the formula (1) or the imidized polymer of the polyimide precursor has a weight average molecular weight of 5,000 to 300,000. 5. The method according to any one of claims 1 to 4,
Wherein the content of the polymer is 1 wt% or more and 10 wt% or less. A liquid crystal alignment film obtained by applying and firing a liquid crystal aligning agent for a photo alignment method according to any one of claims 1 to 6. A liquid crystal alignment film obtained by applying and firing a liquid crystal aligning agent for a photo alignment method according to any one of claims 1 to 6, irradiating linearly polarized ultraviolet rays, and washing the liquid crystal aligning agent with a cleaning liquid. 9. A liquid crystal display element comprising the liquid crystal alignment film according to claim 7 or 8.