KR102104154B1 - Method for producing liquid crystal alignment film, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

(X₁ 은 식 (X1-1) 또는 (X1-2) 이고, R₁ 은 수소 원자 또는 탄소수 1 ∼ 4 의 알킬기이다)

Provided are a method for manufacturing a liquid crystal alignment film for a photo-alignment treatment method capable of suppressing an afterimage caused by AC driving in a liquid crystal display device of an IPS driving method or an FFS driving method, a liquid crystal alignment film, and a liquid crystal display device. Imide obtained by coating and firing a liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor having a structural unit represented by formula (1) and an imidized polymer of the polyimide precursor The polarized radiation was irradiated onto the film thus formed, and then contacted with a lower alkyl ester having 1 to 5 carbon atoms of lactic acid.

(X ₁ is a formula (X1-1) or (X1-2), and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms)

Description

METHOD FOR PRODUCING LIQUID CRYSTAL ALIGNMENT FILM, LIQUID CRYSTAL ALIGNMENT FILM, AND LIQUID CRYSTAL DISPLAY ELEMENT

The present invention relates to a method for producing a liquid crystal alignment film for a photo-alignment method, a liquid crystal alignment film obtained by the manufacturing method, and a liquid crystal display device comprising the obtained liquid crystal alignment film.

In the liquid crystal display element used for a liquid crystal television, a liquid crystal display, etc., the liquid crystal aligning film for controlling the arrangement state of a liquid crystal is normally formed in the element.

The liquid crystal alignment film which is currently most widely used in the industry is so-called rubbing in which the surface of a film made of polyamic acid and / or imidized polyimide formed on an electrode substrate is rubbed in one direction with a cloth such as cotton, nylon, or polyester. It is manufactured by performing treatment.

The rubbing treatment of the film surface in the alignment process of the liquid crystal alignment film is an industrially useful method that is simple and excellent in productivity. However, the demand for high performance, high definition, and large size of the liquid crystal display device is increasingly high, and the surface of the alignment film generated by rubbing treatment is scratched, oscillated, influenced by mechanical force or static electricity, and further, non-uniformity in the alignment surface. Various problems, such as, have been clarified.

As a method to replace the rubbing treatment, a photo-alignment method is known that imparts liquid crystal alignment ability by irradiating polarized radiation. As the liquid crystal alignment treatment by the photo-alignment method, one using a photoisomerization reaction, one using a photocrosslinking reaction, one using a photolysis reaction, etc. have been proposed (see Non-Patent Document 1).

On the other hand, the usefulness of the liquid crystal aligning film for photo-alignment using polyimide is expected because it has high heat resistance compared with others.

In patent document 1, it is proposed to use the polyimide film which has an alicyclic structure, such as a cyclobutane ring, in a main chain for a photo-alignment method.

The photo-alignment method as described above, as a rubbing-less alignment treatment method, not only has the advantage of being industrially produced by a simple manufacturing process, but also a liquid crystal display device of an IPS driving method or a fringe field switching (hereinafter FFS) driving method. In the above, it is possible to improve the performance of the liquid crystal display device by using the liquid crystal alignment film obtained by the photo-alignment method, as compared to the liquid crystal alignment film obtained by the rubbing treatment method, where improvement in contrast and viewing angle characteristics of the liquid crystal display device can be expected. Therefore, it has attracted attention as a promising method for liquid crystal alignment.

As a liquid crystal alignment film used in the IPS driving method or the FFS driving type liquid crystal display device, in addition to basic characteristics such as excellent liquid crystal alignment and electrical characteristics, an IPS (In-Place-Switching) driving method or an FFS driving liquid crystal display It is necessary to suppress afterimages caused by long-term alternating current drive generated in the device.

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 small compared with that by rubbing. When the anisotropy is small, sufficient liquid crystal alignment property is not obtained, and a problem such as an afterimage occurs when the liquid crystal display element is used.

On the other hand, as a method of increasing the anisotropy of the liquid crystal alignment film obtained by the photo-alignment method, by washing or heating treatment with a water-soluble organic solvent after light irradiation, the main chain of the polyimide is cut by light irradiation, resulting in low molecular weight. Although it has been proposed to remove the components, it has not been reached to solve the suppression of afterimages (see Patent Document 2).

Japanese Patent Application Publication No. Hei 9-297313 Japanese Patent Application Publication No. 2011-107266

“Liquid Crystal Alignment Film” Kidouki, Ichimura Functional Materials November 1997 Vol.17, No.11 13-22 pages

The present invention has a liquid crystal alignment film for a photo-alignment treatment method capable of suppressing an afterimage caused by AC driving in a liquid crystal display device of an IPS driving method or an FFS driving method, a method of manufacturing the liquid crystal alignment film, and a liquid crystal alignment film thereof It is an object to provide a liquid crystal display element.

The present inventors conducted extensive studies to achieve the above object, and as a result, irradiated with polarized radiation on the film obtained by coating and firing a polyimide film or a polyimide precursor having a specific structure, followed by carbon number of lactic acid 1 The above-mentioned object can be achieved by a liquid crystal alignment film which is subjected to contact treatment such as dipping using a lower alkyl ester of ˜5, and preferably contacted with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C. I figured it out.

In this way, this invention makes the following a summary.

1. A liquid crystal aligning agent containing at least one 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 is coated on a substrate and fired A method for producing a liquid crystal alignment film comprising irradiating polarized radiation on the imidized film obtained, and then contacting it with a lower alkyl ester having 1 to 5 carbons of lactic acid.

[Formula 1]

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

[Formula 2]

2. The manufacturing method of the liquid crystal aligning film of said 1 whose content of the polymer in the said liquid crystal aligning agent is 2-8 mass%.

3. The method for producing a liquid crystal alignment film according to 1 or 2, wherein the polymer has a weight average molecular weight of 5,000 to 300,000 and a number average molecular weight of 2,500 to 150,000.

4. Preparation of the liquid crystal aligning film according to any one of 1 to 3 above, which is contacted with a lower alkyl ester having 1 to 5 carbon atoms of the lactic acid and further treated with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C. Way.

5. The method for producing a liquid crystal alignment film according to 4 above, wherein the water-soluble organic solvent having the boiling point of 50 to 105 ° C is at least one selected from the group consisting of methanol, ethanol, 2-propanol, and acetone.

6. The manufacturing method of the liquid crystal aligning film in any one of said 1-5 whose said lower alkyl ester is ethyl lactate.

7. The said 1-which is at least 1 sort (s) selected from the group which consists of a polyimide precursor containing 60 mol% or more of the structural unit represented by said Formula (1), and an imidized polymer of this polyimide precursor. The manufacturing method of the liquid crystal aligning film in any one of 3.

8. The liquid crystal aligning film obtained by the manufacturing method of the liquid crystal aligning film in any one of said 1-7.

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

When the liquid crystal aligning film obtained by the manufacturing method of the liquid crystal aligning film of this invention is used as the liquid crystal aligning film of the liquid crystal display element of IPS drive system or FFS drive system, afterimage by long-term AC drive can be reduced very effectively.

<Polyimide precursor of specific structure and imidized polymer thereof>

The polyimide precursor and its imidized polymer in the present invention are polyimide precursors and imidized polymers having a structural unit represented by the following formula (1).

[Formula 3]

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

[Formula 4]

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

The said polyimide precursor and its imidized polymer may contain the structural unit represented by following formula (2) other than the structural unit represented by said formula (1).

[Formula 5]

In Formula (2), R ₁ is the same definition as R _{1 in} Formula (1).

X ₂ is a tetravalent organic group, and its structure is not particularly limited. Specific examples thereof include structures such as the formulas (XA-1), (XA-2), and the following formulas (X-1) to (X-42).

From the viewpoint of compound availability, the structure of X is XA-1, XA-2, X-1 to X-9, X-17, X-25, X-26, X-27, X-28, X-32, X-39 etc. are mentioned.

Moreover, it is preferable to use the tetracarboxylic dianhydride which has an aromatic ring structure from a viewpoint that the liquid crystal aligning film with which relaxation of the residual electric charge accumulated by DC voltage is quick can be obtained, and as the structure of X, X-26 , X-27, X-28, X-32, X-35, X-37 and the like are more preferable.

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

[Formula 10]

In the formula (2), Y ₂ is a divalent organic group, and its structure is not particularly limited. Specific examples of Y _2, for example, there may be mentioned a structure of the formula (Y-1) ~ (Y -85).

[Formula 11]

[Formula 12]

[Formula 13]

[Formula 14]

[Formula 15]

[Formula 16]

[Formula 17]

[Formula 18]

[Formula 19]

Since the improvement of liquid crystal alignability can be expected, a structure with high linearity is preferable as the structure of Y ₂ . As a specific example, Y-74, Y-75, Y-76, Y-77, and Y-78 are more preferable.

Moreover, since improvement of solubility of the polyimide precursor and the polyimide in an organic solvent can be expected, the structure of Y ₂ is Y-8, Y-20, Y-21, Y-22, Y-28, Y -29, Y-30, Y-71, Y-72, Y-73, Y-85 are more preferable.

In the polyimide precursor and its imidized polymer described in the present invention, when the ratio of the structural unit represented by the formula (1) is low, the liquid crystal alignment of the liquid crystal alignment film is lowered, so that the structural unit represented by the formula (1) The proportion is preferably 100 to 60 mol%, more preferably 100 to 80 mol%, per 1 mol of the total structural units.

<Method for producing polyamic acid ester>

The polyamic acid ester which is a polyimide precursor used in the present invention can be synthesized by the methods (1) to (3) shown below.

(1) When synthesized from polyamic acid

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

Specifically, the polyamic acid and the esterifying agent can be synthesized by reacting at -20 to 150 ° C, preferably 0 to 50 ° C, in the presence of an organic solvent for 30 minutes to 24 hours, preferably 1 to 4 hours. .

As the esterifying agent, it is preferable that it can be easily removed by purification, N, N-dimethylformamide dimethylacetal, N, N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal, N, N-dimethylformamidedineopentylbutylacetal, N, N-dimethylformamidedi-t-butylacetal, 1-methyl-3-p-tolyltriagene, 1-ethyl-3-p-tolyltriagene , 1-propyl-3-p-tolyltrigen, 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride, and the like. The amount of the esterifying agent added is preferably 2 to 6 molar equivalents, more preferably 2 to 4 molar equivalents, per 1 mole of the repeating unit of the polyamic acid.

The organic solvent used in the reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc., in the solubility of the polymer, and these are mixed in one or more types You may use it.

The concentration of the polymer in the organic solvent at the time of 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 easily and a high molecular weight body is easily obtained.

(2) When synthesized by reaction of tetracarboxylic acid diester dichloride and diamine

The polyamic acid ester can be synthesized from tetracarboxylic acid diester dichloride and diamine.

Specifically, tetracarboxylic acid diester dichloride and diamine in the presence of a base and an organic solvent at -20 to 150 deg. C, preferably 0 to 50 deg. C, 30 minutes to 24 hours, preferably 1 to 4 hours It can be synthesized by reacting.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine, or the like can be used, and pyridine is preferred to gently advance the reaction. From the viewpoint of easy removal and addition of a high molecular weight body, the amount of the base added is preferably 2 to 4 times mole, more preferably 2 to 3 times mole to tetracarboxylic acid diester dichloride.

The organic solvent used in the above reaction is preferably N-methyl-2-pyrrolidone, γ-butyrolactone, etc. in solubility of monomers and polymers, and these may be used alone or in combination of two or more.

The polymer concentration in the organic solvent at the time of synthesis is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, from the viewpoint that precipitation of the polymer does not occur easily and a high molecular weight body is easily obtained. Further, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, it is preferable that the organic solvent used for the synthesis of the polyamic acid ester is dehydrated as much as possible, and the reaction is carried out in a nitrogen atmosphere to prevent incorporation of outside air. It is desirable to do.

(3) When polyamic acid is synthesized from tetracarboxylic acid diester and diamine

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

Specifically, tetracarboxylic acid diester and diamine are present in the presence of a condensing agent, a base, and an organic solvent at 0 to 150 ° C, preferably 0 to 100 ° C, for 30 minutes to 24 hours, preferably 3 to 15 It can synthesize | combine by making time reaction.

Examples of the condensing agent include triphenylphosphite, dicyclohexylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, N, N'-carbonyldiimidazole, and dimethoxy-1 , 3,5-triazinylmethylmorpholinium, O- (benzotriazol-1-yl) -N, N, N ', N'-tetramethyluroniumtetrafluoroborate, O- (benzotriazole- 1-yl) -N, N, N ', N'-tetramethyluronium hexafluorophosphate, (2,3-dihydro-2-thioxo-3-benzooxazolyl) diphenyl phosphonate, etc. can be used You can. It is preferable that the addition amount of a condensing agent is 2-3 times mole with respect to a tetracarboxylic-acid diester, and 2-2 times mole is more preferable.

As the base, tertiary amines such as pyridine and triethylamine can be used. The addition amount of the base is an amount that is easily removed, and from the viewpoint of easy to obtain a high molecular weight body, 2 to 4 times mole is preferable, and 2 to 3 times mole is more preferable relative to the diamine component.

Examples of the organic solvent include N-methyl-2-pyrrolidone, γ-butyrolactone, and N, N-dimethylformamide.

In addition, in the above reaction, the reaction proceeds efficiently by adding a Lewis acid as an additive. As the Lewis acid, lithium halide such as lithium chloride and lithium bromide is preferred. The amount of the Lewis acid added is preferably 0 to 1.0 times mole, more preferably 2.0 to 3.0 times mole, with respect to the diamine component.

Of the above three methods for synthesizing polyamic acid esters, the method for synthesizing (1) or (2) above is particularly preferred because a high molecular weight polyamic acid ester is 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. The powder of the purified polyamic acid ester can be obtained by performing precipitation several times, washing with a poor solvent, and drying at room temperature or by heating.

The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, and toluene, and water, methanol, ethanol, 2-propanol, and the like are preferred.

<Method for producing polyamic acid>

The polyamic acid which is a polyimide precursor used in the present invention can be synthesized by the method shown below.

Specifically, it is synthesized by reacting tetracarboxylic dianhydride and diamine at -20 to 150 ° C, preferably 0 to 50 ° C, in the presence of an organic solvent for 30 minutes to 24 hours, preferably 1 to 12 hours. can do.

The organic solvent used for the reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone, γ-butyrolactone, etc., in terms of solubility of monomers and polymers. You may mix and use.

The concentration of the polymer is preferably from 1 to 30% by mass, and more preferably from 5 to 20% by mass, from the viewpoint that precipitation of the polymer does not occur easily and a high molecular weight body is easily obtained.

The polyamic acid obtained as described above can be recovered by depositing a polymer by injecting the reaction solution into a poor solvent while stirring well. Moreover, the powder of the purified polyamic acid can be obtained by performing precipitation several times, washing with a poor solvent, and drying at room temperature or by heating. The poor solvent is not particularly limited, and examples thereof include water, methanol, ethanol, 2-propanol, hexane, butyl cellosolve, acetone, and toluene, and water, methanol, ethanol, 2-propanol, and the like are preferred.

<Method for producing polyimide>

The polyimide used in the present invention can be produced by imidizing the polyamic acid ester or polyamic acid.

When producing a polyimide from a polyamic acid ester, chemical imidation is simple by adding a basic catalyst to the polyamic acid ester solution or a polyamic acid solution obtained by dissolving a polyamic acid ester resin powder in an organic solvent. Chemical imidation is preferable because the imidization reaction proceeds at a relatively low temperature, and the molecular weight of the polymer does not easily decrease in the course of imidization.

Chemical imidation can be performed by stirring the polyamic acid ester to be imidized in an organic solvent in the presence of a basic catalyst. As the organic solvent, a solvent used in the polymerization reaction described above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, triethylamine is preferred because it has sufficient basicity to advance the reaction.

The temperature at the time of performing the imidization reaction is -20 to 140 ° C, preferably 0 to 100 ° C, and the reaction time can be carried out at 1 to 100 hours.

The amount of the basic catalyst is 0.5 to 30 times mole of the amic acid ester group, and preferably 2 to 20 times mole.

The imidation rate of the obtained polymer can be controlled by adjusting the catalyst amount, temperature, and reaction time.

When polyimide is prepared from polyamic acid, chemical imidation is simple by adding a catalyst to the solution of the polyamic acid obtained by reaction of a diamine component and tetracarboxylic dianhydride. Chemical imidation is preferable because the imidization reaction proceeds at a relatively low temperature and the molecular weight of the polymer does not easily decrease due to the imidization process.

Chemical imidation can be performed by stirring the polymer to be imidized in an organic solvent in the presence of a basic catalyst and an acid anhydride. As the organic solvent, a solvent used in the polymerization reaction described above can be used. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Among them, pyridine is preferred because it has basicity suitable for advancing the reaction. Further, examples of the acid anhydride include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Among these, acetic anhydride is preferred because purification after completion of the reaction becomes easy.

The temperature at the time of performing the imidization reaction is -20 to 140 ° C, preferably 0 to 100 ° C, and the reaction time can be carried out at 1 to 100 hours.

The amount of the basic catalyst is 0.5 to 30 times mole of the polyamic acid group, preferably 2 to 20 times mole, and the amount of the acid anhydride is 1 to 50 times mole, preferably 3 to 30 times mole of the polyamic acid group.

The imidation rate of the obtained polymer can be controlled by adjusting the catalyst amount, temperature, and reaction time.

Since the added catalyst or the like remains in the solution after the imidation reaction of the polyamic acid ester or the polyamic acid, the imidized polymer obtained is recovered by the means described below, re-dissolved with an organic solvent, and the liquid crystal of the present invention It is preferable to use it as an alignment agent.

The solution of the polyimide obtained as described above can be precipitated by injecting it into a poor solvent while stirring well. Precipitation is carried out several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polymer powder.

The poor solvent is not particularly limited, and examples include methanol, 2-propanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, and the like, methanol, ethanol, 2-propanol, acetone and the like are preferred.

<Liquid crystal aligning agent>

The liquid crystal aligning agent used in the present invention has a form in which a polymer component is dissolved in an organic solvent. The molecular weight of the polymer is preferably 2,000 to 500,000 as a weight average molecular weight, more preferably 5,000 to 300,000, and even more preferably 10,000 to 100,000. Moreover, 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 depending on the thickness setting of the coating film to be formed, and is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film. It is preferable to set it as 10 mass% or less from a viewpoint of storage stability. The concentration of the particularly preferred polymer is 2 to 8% by mass.

The organic solvent contained in the liquid crystal aligning agent used in the present invention is not particularly limited as long as the polymer component is uniformly dissolved. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone , N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-me And methoxy-N, N-dimethylpropanamide. You may use these 1 type or in mixture of 2 or more types. Moreover, even if it is a solvent which cannot melt | dissolve a polymer component uniformly by itself, if it is the range in which a polymer does not precipitate, you may mix with said organic solvent.

The liquid crystal aligning agent used in the present invention may contain, in addition to an organic solvent for dissolving the polymer component, a solvent for improving coating film uniformity when the liquid crystal aligning agent is applied to the substrate. As the solvent, a solvent having a surface tension lower than that of the organic solvent is generally used. As specific examples, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether- 2-acetate, butyl cellosolve acetate, dipropylene glycol, 2- (2-ethoxypropoxy) propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate Esters and the like. You may use 2 or more types of these solvents together.

To the liquid crystal aligning agent of the present invention, in addition to the above, if the effect of the present invention is not inhibited, a polymer other than the polymer, a dielectric or conductive material for the purpose of changing electrical properties such as dielectric constant and conductivity of the liquid crystal aligning film, and the liquid crystal aligning film A silane coupling agent for the purpose of improving the adhesion of the substrate, a crosslinkable compound for the purpose of increasing the hardness or density of the film when used as a liquid crystal alignment film, and furthermore, for the purpose of efficiently proceeding the imidization of the polyamic acid when firing the coating film. An imidization accelerator or the like may be added.

<Method for producing a liquid crystal alignment film>

The manufacturing method of the liquid crystal aligning film of this invention is a process of apply | coating and baking a liquid crystal aligning agent to a board | substrate, the process of irradiating the polarized radiation to the obtained film, and contacting the irradiated film with the lower alkyl ester of lactic acid 1-5. After treatment, preferably, it has a step of contacting with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C.

(1) Process of coating and firing liquid crystal aligning agent on substrate

A polyimide film or a film obtained by imidizing a polyimide precursor is obtained by applying the liquid crystal aligning agent obtained as described above to a substrate, drying and firing.

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, or the like can be used, and liquid crystal driving is performed. It is preferable to use a substrate on which an ITO (Indium Tin Oxide) electrode is formed. In addition, in the reflective liquid crystal display element, an opaque material such as a silicon wafer can be used as long as it is only on one side of the substrate. In this case, a material that reflects light such as aluminum can also be used.

As a coating method of the liquid crystal aligning agent used for this invention, a spin coat method, a printing method, an inkjet method, etc. are mentioned.

Any temperature and time can be selected for the drying and firing steps after applying the liquid crystal aligning agent. Usually, in order to sufficiently remove the contained organic solvent, it is dried at 50 to 120 ° C, preferably 60 to 100 ° C for 1 to 10 minutes, and then 150 to 300 ° C, preferably 200 to 250 ° C, 5 It is fired for ~ 120 minutes. The thickness of the coating film after firing is not particularly limited, but if it is too thin, reliability of the liquid crystal display element may be lowered, so it is 5 to 300 nm, preferably 10 to 200 nm.

(2) Process of irradiating polarized radiation to the obtained film

By irradiating polarized radiation to the film obtained by the method (1) (hereinafter also referred to as light alignment treatment), anisotropy is imparted in the direction perpendicular to the polarization direction.

As a specific example of a photo-alignment process, the method of providing the liquid crystal aligning ability by irradiating the surface of the said coating film with the radiation polarized in the predetermined direction. As the wavelength of 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 preferable, and ultraviolet rays having a wavelength of 200 to 400 nm are particularly preferable. It is preferable that the radiation dose is 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. The temperature of irradiating polarized radiation to the film is preferably carried out at 10 to 100 ° C, more preferably 20 to 50 ° C.

(3) Process of contact treatment with lactic acid ester

In the step (2), the film irradiated with the polarized radiation is then contact-treated with a lower alkyl ester having 1 to 5 carbon atoms of lactic acid, preferably, with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C. Contact processing.

Examples of the lower alkyl ester having 1 to 5 carbon atoms of lactic acid used for the contact treatment include ethyl lactate, methyl lactate, butyl lactate, and the like, and alkyl esters having 1 to 3 carbon atoms are particularly preferred. The lactic acid alkyl ester may be used alone, or may contain other solvents or solvents other than the lactic acid alkyl ester within a range that does not impair the effects of the present invention. Although it does not specifically limit as these other solvents, Water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, propylene glycol monomethyl ether acetate, etc. are mentioned. In particular, water is more preferable from the viewpoint of versatility and safety.

When the other solvent is contained, the content of the alkyl lactic acid ester is preferably 50 to 100 mass%, more preferably 70 to 100 mass%, and 90 to 100 mass%, based on the total amount of the solution used for the contact treatment. % Is particularly preferred.

In the present invention, the contact treatment between the film irradiated with polarized radiation and the alkyl lactic acid ester is preferably a treatment in which a film and a liquid such as an immersion treatment or a spray (spray) treatment are sufficiently contacted. Especially, the method of immersing a film in an lactic acid alkyl ester, Preferably it is 10 second-1 hour, More preferably, it is 1-30 minutes, It is preferable. The contact treatment may be either room temperature or heated, but is preferably carried out at 10 to 80 ° C, more preferably at 20 to 50 ° C. In addition, a means for increasing contact such as ultrasonic waves can be implemented as necessary.

In the present invention, it is preferable to perform a contact treatment with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C, preferably 50 to 80 ° C, after the contact treatment with the alkyl lactate ester. As such a water-soluble organic solvent having a boiling point of 50 to 105 ° C, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, and the like are preferable.

The contact treatment with the alkyl lactic acid ester, followed by water or a treatment with a water-soluble organic solvent having a boiling point of 50 to 105 ° C, may be carried out continuously or over time. In the latter case, it is not preferable to leave too much time, so it is preferable to carry out continuously.

After the contact treatment with the lactic acid alkyl ester, preferably after the contact treatment with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C, drying is preferably performed. The temperature of the drying treatment is preferably 80 to 250 ° C, more preferably 80 to 150 ° C, and the drying time is preferably 10 seconds to 30 minutes, more preferably 30 seconds to 10 minutes.

<Liquid crystal display element>

The liquid crystal display element of this invention is obtained by the manufacturing method of this invention, and after obtaining the board | substrate with the liquid crystal aligning film obtained from a liquid crystal aligning agent, a liquid crystal cell is manufactured by a well-known method, and the liquid crystal display element is used using this liquid crystal cell. It is done.

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, a liquid crystal display element having an active matrix structure may be formed 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, and a common (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 to display desired images. Subsequently, an insulating film is formed by covering the common electrode and the segment electrode on each substrate. The insulating film can be, for example, a film made of SiO ₂ -TiO ₂ formed by the sol-gel method.

Next, the liquid crystal aligning film of this invention is formed on each board | substrate.

Next, the other substrates are superimposed on one of the substrates so that the alignment film surfaces of each other face each other, and the periphery is bonded with a sealing material. Spacers are usually incorporated into the sealing material to control the substrate gap. Moreover, it is preferable to distribute the spacer for board | substrate clearance control also in the in-plane part which does not form a sealing material. An opening capable of filling the liquid crystal from the outside is formed in a part of the sealing material.

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, the opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method using a capillary phenomenon in the atmosphere may be used. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates are affixed to the surface opposite to the liquid crystal layer of the two substrates. The liquid crystal display element of this invention is obtained by passing through the above process.

Since this liquid crystal display element uses the liquid crystal aligning film obtained by the manufacturing method of the liquid crystal aligning film of this invention as a liquid crystal aligning film, it becomes what is excellent in an afterimage property, and is suitable for a large screen, high definition liquid crystal television, etc ..

Example

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these.

The symbol of the compound used in the Example and the comparative example, and the measuring method of each characteristic are as follows.

NMP: N-methyl-2-pyrrolidone

GBL: γ-butyrolactone

BCS: Butyl Cellosolve

IPA: 2-propanol

DE-1: the following formula (DE-1)

DA-1: the following formula (DA-1)

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

(Boc group represents a t-butoxycarbonyl group)

Additive A: N-α- (9-fluorenylmethoxycarbonyl) -N-τ-t-butoxycarbonyl-L-histidine

[Formula 20]

The methods of viscosity, molecular weight, imidation rate, liquid crystal cell production, and afterimage evaluation by long-term alternating current drive are shown below.

[Viscosity]

In the synthesis example, the viscosity of the polyamic acid ester and the polyamic acid solution is 1.1 ml of sample volume using an E-type viscometer TVE-22H (manufactured by Toki Sangyo), cone rotor TE-1 (1 ° 34 ', R24), temperature It measured at 25 degreeC.

[Molecular Weight]

The molecular weight of the polyamic acid ester was measured by a GPC (normal temperature gel permeation chromatography) apparatus, and the number average molecular weight (Mn) and weight average molecular weight (Mw) were calculated as the polyethylene glycol and polyethylene oxide conversion values.

GPC device: manufactured by Shodex (GPC-101)

Column: manufactured by Shodex (series of KD803, KD805)

Column temperature: 50 ℃

Eluent: N, N-dimethylformamide (Lithium bromide-hydrate (LiBrH ₂ O) as additive) is 30 mmol / L (liters), phosphoric acid and anhydrous crystals (o-phosphoric acid) are 30 mmol / L, tetra Hydrofuran (THF) is 10 ml / ℓ)

Flow rate: 1.0 ml / min

Standard sample for calibration curve preparation: TSK standard polyethylene oxide manufactured by Tosoh Corporation (weight average molecular weight (Mw) about 900,000, 150,000, 100,000, 30,000), and polyethylene glycol manufactured by Polymer Laboratories (peak top molecular weight (Mp) about 12,000) , 4,000, 1,000). The measurement was performed separately on two samples of samples in which four types of 900,000, 100,000, 12,000, and 1,000 were mixed, and samples of three types of 150,000, 30,000, and 4,000 were mixed to avoid overlapping peaks.

[Measurement of imidation rate]

The imidation ratio of the polyimide in the synthesis example was measured as follows. 20 mg of polyimide powder was placed in an NMR sample tube (NMR sampling tube standard, φ5 (manufactured by Kusano Scientific)), and deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53 mL) Was added and ultrasonically added to dissolve completely. This solution was measured for a 500 MHz proton NMR by an NMR meter (JNW-ECA500) (manufactured by Nihon Electronics Datum Co., Ltd.). The imidation rate determines the proton derived from a structure that does not change before and after imidation as a reference proton, and the peak integrated value of this proton and a proton peak derived from the NH group of amic acid appearing around 9.5 ppm to 10.0 ppm. It calculated | required by the following formula using the integrated value.

Imidation rate (%) = (1-α · x / y) × 100

In the above formula, x is a proton peak integrated value derived from NH group of amic acid, y is a peak integrated value of reference proton, α is NH of amic acid in the case of polyamic acid (imidation rate is 0%) This is the ratio of the number of reference protons to one proton.

[Preparation of liquid crystal cell]

A liquid crystal cell having a configuration of a fringe field switching (hereinafter referred to as FFS) mode liquid crystal display element is manufactured.

First, an electrode-formed substrate was prepared. The substrate is a glass substrate having a size of 30 mm × 50 mm and a thickness of 0.7 mm. On the substrate, an ITO electrode having a beta-like pattern constituting a counter electrode as a first layer is formed. On the counter electrode of the first layer, as the second layer, a SiN (silicon nitride) film formed by a CVD (Chemical Vapor Deposition) method is formed. The thickness of the second layer of the SiN film is 500 nm, and functions as an interlayer insulating film. On the second layer of the SiN film, a comb-shaped pixel electrode formed by patterning an ITO film as the third layer is disposed, and two pixels of the first pixel and the second pixel are formed. 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 by the action of the SiN film of the second layer.

The pixel electrode of the third layer has a comb-shaped shape formed by arranging a plurality of U-shaped electrode elements in which a central portion is bent. The width in the width direction of each electrode element is 3 μm, and the spacing between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is formed by arranging a plurality of U-shaped electrode elements in which the central portion is bent, the shape of each pixel is not a rectangular shape, but a thick, curved portion in the central portion like the electrode element. It has a shape similar to the letter K. And each pixel is divided | segmented up and down with the central curved part as a boundary, and has a 1st upper area | region and a 2nd lower area | region of a curved part.

When the first region and the second region of each pixel are compared, the direction of formation of the electrode elements of the pixel electrodes constituting them is different. That is, when the rubbing direction of the liquid crystal aligning film, which will be described later, is used as a reference, in the first region of the pixel, the electrode element of the pixel electrode is formed to form an angle (clockwise) of + 10 °, and in the second region of the pixel, the electrode of the pixel electrode The element is formed to form an angle of -10 ° (clockwise). That is, in the first area and the second area of each pixel, the directions of rotation operations (inflation / switching) within the substrate surface of the liquid crystal caused by the application of the voltage between the pixel electrode and the counter electrode are opposite to each other. Consists of.

Next, the obtained liquid crystal aligning agent was filtered through a 1.0 µm filter, and then applied by spin coating to a substrate on which the prepared electrode was formed and a glass substrate having a columnar spacer having a height of 4 µm with an ITO film formed on the back surface. . After drying on a hot plate at 80 ° C for 5 minutes, baking was performed for 20 minutes in a hot air circulation oven at 230 ° C to form a coating film having a film thickness of 100 nm. An ultraviolet ray having a wavelength of 254 nm linearly polarized with an extinction ratio of 10: 1 or more was irradiated through a polarizing plate on the surface of this coating film. This substrate was immersed in a solution containing ethyl lactate for 3 minutes, and then immersed in pure water for 1 minute, and dried on a hot plate at 80 ° C for 5 minutes to obtain a substrate on which a liquid crystal alignment film was formed. Set the two substrates as one set, print a sealing agent on the substrate, attach the other one of the substrates with the liquid crystal alignment film face to face and the orientation direction to be 0 °, and then cure the sealing agent to form a void. Cells were prepared. A liquid crystal MLC-2041 (manufactured by Merck) was injected into the empty cell by a reduced pressure 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 ° C. for 1 hour and left for overnight to use in each evaluation.

[Afterimage evaluation by long-term AC drive]

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

Using this liquid crystal cell, an alternating voltage of ± 5 V was applied for 120 hours at a frequency of 60 Hz in a constant temperature environment of 60 ° C. Thereafter, the state between the pixel electrode and the counter electrode of the liquid crystal cell was short-circuited and left at room temperature for one day.

After standing, the liquid crystal cell was placed between two polarizing plates arranged so that the polarization axes were orthogonal to each other, and the backlight was turned on in a voltage-free state, and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of transmitted light was the smallest. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel is darkest to the angle at which the first region is darkest was calculated as the angle Δ. Similarly in the second pixel, the second region and the first region were compared to calculate the same angle Δ. Then, the average value of the angle Δ value of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell.

(Synthesis Example 1)

A 3000 ml four-necked flask with a stirring device was placed in a nitrogen atmosphere, and 114.33 g (468 mmol) of 1,2-bis (4-aminophenoxy) ethane was added, and 12.33 g (52.0 mmol) of DA-2. It was added, and 1810 g of NMP was added and dissolved by stirring while conveying nitrogen. While stirring the diamine solution, 1,2,3,4-cyclobutanetetracarboxylic dianhydride was added to 96.87 g (494 mmol), NMP was further added at a solid content concentration of 10% by mass, and at room temperature. The mixture was stirred for 24 hours to obtain a solution of polyamic acid (PAA-1). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 159 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 13090 and Mw = 34272.

(Synthesis Example 2)

18.0 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was added to a 50 ml sample tube containing a stirrer, 6.05 g of NMP, 6.00 g of BCS, and 0.26 g of additive A, and 30 with a magnetic stirrer. The mixture was stirred for a minute to obtain a liquid crystal aligning agent (A-1).

(Synthesis Example 3)

124.60 g (510 mmol) of 1,2-bis (4-aminophenoxy) ethane and 0.95 g (90.0 mmol) of DA-2 were added to a 3000 ml 4-neck flask with a stirring device and nitrogen introduction tube, and NMP 2236 g was added and dissolved by stirring while conveying nitrogen. While stirring this diamine solution, 130.06 g (580.2 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid anhydride was added, and the solid content concentration was further 10 mass%. NMP was added and stirred at room temperature for 24 hours to obtain a solution of polyamic acid (PAA-2). The viscosity of the polyamic acid solution at a temperature of 25 ° C was 511 mPa · s. Moreover, the molecular weight of this polyamic acid was Mn = 19100 and Mw = 46880.

(Synthesis Example 4)

18.0 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 3 was added to a 50 ml sample tube containing a stirrer, 18.01 g of NMP, 9.03 g of BCS, and 0.25 g of additive A were added, and 30 was added with a magnetic stirrer. The mixture was stirred for a minute to obtain a liquid crystal aligning agent (A-2).

(Synthesis Example 5)

200 g of the obtained polyamic acid solution (PAA-2) was added to a 500 mL four-neck flask in which a stirring device and a nitrogen introduction tube were formed, and NMP was added to 85.68 g, followed by stirring for 30 minutes. To the obtained polyamic acid solution, 22.22 g of acetic anhydride and 6.86 g of pyridine were added, followed by heating at 50 ° C for 3 hours to perform chemical imidization. The obtained reaction solution was poured into 1100 g of methanol while stirring, and the precipitated precipitate was collected by filtration, and then washed three times with 1100 g of methanol and washed twice with 200 g of methanol. Polyimide resin powder was obtained by drying the obtained resin powder at 60 degreeC for 12 hours.

The imidation ratio of this polyimide resin powder was 68%, and the molecular weights were Mn = 9155 and Mw = 21430.

Further, 12.53 g of the obtained polyimide resin powder was added to a 200 ml sample tube containing a stirrer, 91.89 g of NMP was added, and the mixture was stirred and dissolved at room temperature for 24 hours to obtain a polyimide solution (PI-1).

(Synthesis Example 6)

59.59 g of the polyimide solution (PI-1) obtained in Synthesis Example 5 was added to a 200 ml sample tube containing a stirrer, 7.17 g of an NMP solution of 0.3% by mass 3-glycidoxypropylmethyldiethoxysilane, and 11.26 g of NMP. , 26.0 g of BCS and 2.08 g of additive A were added and stirred for 30 minutes with a magnetic stirrer to obtain a liquid crystal aligning agent (A-3).

(Synthesis Example 7)

A 500 ml four-necked flask with a stirring device was used in a nitrogen atmosphere, and 7.01 g (28.7 mmol) of 1,2-bis (4-aminophenoxy) ethane was added, and 1.21 g (3.19 mmol) of DA-2 was added. It was put, 76.0 g of NMP, 227.9 g of GBL, and 5.69 g (71.9 mmol) of pyridine as a base were added and dissolved by stirring. Next, while stirring this diamine solution, 29.98 g (30.0 mmol) of DE-1 was added and reacted at 15 ° C for 24 hours. After stirring for 24 hours, 0.83 g (9.18 mmol) of acryloyl chloride was added and reacted at 15 ° C for 4 hours. The resulting polyamic acid ester solution was added to 983 g of 2-propanol with stirring, and the precipitated white precipitate was collected by filtration, and then washed with 328 g of 2-propanol five times, and dried to obtain a white polyamic acid ester. A resin powder was obtained. Moreover, the molecular weight of this polyamic acid ester was Mn = 15224 and Mw = 32484.

Further, 3.13 g of the obtained polyamic acid ester resin powder was added to a 30 ml sample tube containing a stirrer, 28.12 g of GBL was added, and the mixture was stirred and dissolved at room temperature for 24 hours to obtain a polyamic acid ester solution (PAE-1).

(Synthesis Example 8)

To a 30 ml sample tube containing a stirrer, 7.52 g of the polyamic acid ester solution (PAE-1) obtained in Synthesis Example 7 was added, 5.01 g of GBL, 3.00 g of BCS, and 0.14 g of additive A were added, and a magnetic stirrer was used. The mixture was stirred for 30 minutes to obtain a liquid crystal aligning agent (A-4).

<Example 1>

After filtering the liquid crystal aligning agent (A-1) obtained in Synthesis Example 2 with a 1.0 μm filter, the prepared electrode was formed on a substrate and a glass substrate having a columnar spacer having a height of 4 μm with an ITO film formed on the back surface. It was applied by spin coat application. After drying on a hot plate at 80 ° C for 5 minutes, baking was performed for 20 minutes in a hot air circulation oven at 230 ° C to form a coating film having a film thickness of 100 nm. 1.0 J / cm <2> of ultraviolet-rays of wavelength 254nm linearly polarized with the extinction ratio 26: 1 were irradiated through the polarizing plate on this coating film surface. This substrate was immersed in ethyl lactate for 3 minutes at room temperature (25 ° C), then immersed in pure water for 1 minute, and dried on a hot plate at 80 ° C for 5 minutes to obtain a substrate on which a liquid crystal alignment film was formed. The above two substrates were set as one set, a sealing agent was printed on the substrate, and the other one of the substrates was pasted with the liquid crystal alignment film faced so that the alignment direction was 0 °, and then the sealing agent was cured to prepare a blank cell. . A liquid crystal MLC-2041 (manufactured by Merck) was injected into the empty cell by a reduced pressure 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 ° C. for 1 hour, left overnight, and afterimage evaluation by long-term AC driving was performed. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.44 degrees.

<Example 2>

Using the liquid crystal aligning agent (A-2) obtained in Synthesis Example 4, 0.2 J / of UV light having a linearly polarized wavelength of 254 nm with an extinction ratio of 26: 1 was interposed through a polyimide film coated, dried, and fired on a substrate. An FFS-driven liquid crystal cell was manufactured in the same manner as in Example 1 except that the cm2 was irradiated. The residual image evaluation by long-term AC drive was performed about this FFS drive liquid crystal cell. The angle Δ value of this liquid crystal cell after long-term AC driving was 0.12 degrees.

<Example 3>

Using the liquid crystal aligning agent (A-3) obtained in Synthesis Example 6, a polyimide film coated, dried, and fired on a substrate was interposed with a polarizing plate, and the linearly polarized wavelength of 254 nm with an extinction ratio of 26: 1 was 0.2 J / An FFS-driven liquid crystal cell was manufactured in the same manner as in Example 1 except that the cm2 was irradiated. The residual image evaluation by long-term AC drive was performed about this FFS drive liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.10 degrees.

<Example 4>

Using the liquid crystal aligning agent (A-4) obtained in Synthesis Example 8, a polyimide film coated, dried, and fired on a substrate was interposed with a polarizing plate and a linearly polarized wavelength of 254 nm with an extinction ratio of 26: 1 was 0.2 J / An FFS-driven liquid crystal cell was manufactured in the same manner as in Example 1 except that the cm2 was irradiated. The residual image evaluation by long-term AC drive was performed about this FFS drive liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.08 degrees.

<Comparative Example 1>

After filtering the liquid crystal aligning agent (A-1) obtained in Synthesis Example 2 with a 1.0 µm filter, the prepared electrode was formed on a substrate and a glass substrate having a columnar spacer having a height of 4 µm with an ITO film formed on the back surface. It was applied by spin coat application. After drying on a hot plate at 80 ° C for 5 minutes, baking was performed for 20 minutes in a hot air circulation oven at 230 ° C to form a coating film having a film thickness of 100 nm. 1.0 J / cm <2> of ultraviolet-rays of wavelength 254nm linearly polarized with the extinction ratio 26: 1 were irradiated through the polarizing plate on this coating film surface.

This substrate was immersed in a mixed solution of IPA and pure water (mass ratio: IPA / pure water = 5/5) for 3 minutes at room temperature, then immersed in pure water for 1 minute, and dried on a hot plate at 80 ° C for 5 minutes to form a liquid crystal alignment film. The formed substrate was obtained. The above two sheets were set as one set, a sealing agent was printed on the substrate, and another one of the substrates was pasted with the liquid crystal alignment film faced so that the alignment direction was 0 °, and then the sealing agent was cured to prepare a blank cell. . A liquid crystal MLC-2041 (manufactured by Merck) was injected into the empty cell by a reduced pressure 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 ° C. for 1 hour, left overnight, and afterimage evaluation by long-term AC driving was performed. The value of the angle Δ of this liquid crystal cell after long-term alternating current driving was 0.52 degrees.

<Comparative Example 2>

Using the liquid crystal aligning agent (A-2) obtained in Synthesis Example 4, 0.2 J / of ultraviolet rays having a wavelength of 254 nm linearly polarized with an extinction ratio of 26: 1 was interposed through a polyimide film coated, dried, and fired on a substrate. An FFS-driven liquid crystal cell was manufactured in the same manner as in Comparative Example 1 except for the irradiation with cm 2. The residual image evaluation by long-term AC drive was performed about this FFS drive liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.25 degrees.

<Comparative Example 3>

Using the liquid crystal aligning agent (A-3) obtained in Synthesis Example 6, a polyimide film coated, dried, and fired on a substrate with a polarizing plate interposed therebetween was linearly polarized with an extinction ratio of 26: 1 to a wavelength of 254 nm with ultraviolet light of 0.2 J / An FFS-driven liquid crystal cell was manufactured in the same manner as in Comparative Example 1 except for the irradiation with cm 2. The residual image evaluation by long-term AC drive was performed about this FFS drive liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.20 degrees.

Industrial availability

The liquid crystal aligning film obtained from the liquid crystal aligning agent of the present invention is capable of reducing the afterimage caused by AC driving in the liquid crystal display device of the IPS driving method or the FFS driving method, and the IPS driving method or the FFS driving method having excellent afterimage characteristics. 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.

In addition, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2012-263390, filed on November 30, 2012, are cited herein and taken as an indication of the specification of the present invention.

Claims (9)

An image obtained by coating and firing a liquid crystal aligning agent containing at least one type 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: A method for producing a liquid crystal alignment film comprising irradiating polarized radiation onto a degraded film and then contacting it with a lower alkyl ester having 1 to 5 carbons of lactic acid.
[Formula 1]

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

According to claim 1,
The manufacturing method of a liquid crystal aligning film whose content of the polymer in the said liquid crystal aligning agent is 2-8 mass%. According to claim 1,
A method for producing a liquid crystal alignment film, wherein the polymer has a weight average molecular weight of 5,000 to 300,000 and a number average molecular weight of 2,500 to 150,000. According to claim 1,
The manufacturing method of the liquid crystal aligning film which is made to contact-treat with the lower alkyl ester of 1-5 carbon atoms of the said lactic acid, and to further contact with water or a water-soluble organic solvent which has a boiling point of 50-105 degreeC. The method of claim 4,
A method for producing a liquid crystal alignment film, wherein the water-soluble organic solvent having a boiling point of 50 to 105 ° C is at least one selected from the group consisting of methanol, ethanol, 2-propanol, and acetone. According to claim 1,
A method for producing a liquid crystal alignment film, wherein the lower alkyl ester is ethyl lactate. According to claim 1,
Production of a liquid crystal alignment film which is 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), and an imidized polymer of the polyimide precursor, based on 1 mol of the total polymer. Way. The liquid crystal aligning film obtained by the manufacturing method of the liquid crystal aligning film in any one of Claims 1-7. The liquid crystal display element provided with the liquid crystal aligning film of Claim 8.