KR102101530B1 - Method for producing liquid crystal alignment film, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

(X₁ 은 식 (XA-1), Y₁ 은 2 가의 유기기, R₁ 은 H 등, R₃ ∼ R₆ 은 H 등)Provided is a method of manufacturing a liquid crystal alignment film for photo-alignment that can suppress an afterimage caused by AC driving.
Polarized radiation to a film obtained by applying and firing a liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor represented by formula (1) and an imidized polymer of the polyimide precursor on a substrate After irradiating with, the organic solvent having a boiling point of 110 to 180 ° C is contacted, and then it is treated with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C, followed by heating at 150 ° C or higher.

(X ₁ is a formula (XA-1), Y ₁ is a divalent organic group, R ₁ is H, etc., R ₃ to R ₆ are H, etc.)

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.

Currently, the most widely used liquid crystal alignment film in industry is to rub the surface of a film made of polyamic acid formed on an electrode substrate and / or polyimide obtained by imidizing it in one direction with a cloth such as cotton, nylon, or polyester. It is manufactured by performing 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 that is simple and excellent in productivity. However, demands for high performance, high definition, and large-sized liquid crystal display elements are increasingly high, and surface scratches, oscillations, mechanical forces or static electricity effects caused by rubbing treatment, and furthermore, orientation treatment. Various problems such as non-uniformity in the surface have become clear.

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, since the liquid crystal aligning film for photo-alignment using polyimide has high heat resistance compared with the others, its usefulness is expected. In patent document 1, it is proposed to use the polyimide membrane which has an alicyclic structure, such as a cyclobutane ring, in a main chain for a photo-alignment method.

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

As a liquid crystal aligning film used for the IPS driving method or the FFS driving type liquid crystal display element, in addition to basic characteristics such as excellent liquid crystal alignment and electrical properties, long-term alternating current generated in the IPS driving method or the FFS driving method liquid crystal display element It is necessary to suppress afterimages caused 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 small as compared with that by the rubbing treatment method. When the anisotropy is small, sufficient liquid crystal alignment property is not obtained, and a problem occurs in the occurrence of an afterimage in the case of a liquid crystal display element.

In addition, as a method of increasing the anisotropy of the liquid crystal alignment film obtained by the photo-alignment method, after light irradiation, the low molecular weight component produced by cutting the main chain of the polyimide by light irradiation is washed with a water-soluble organic solvent or Although it is proposed to remove by heat treatment, it has not been able to solve the suppression of an afterimage (see Patent Document 2).

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

 「Liquid Crystal Alignment Film」 Kidoki, Ichimura Functional Materials November 1997 Vol.17, No.11 13-22 pages

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

The present inventors have studied earnestly to achieve the above object, and as a result, a film obtained by coating and firing a polyimide precursor having a specific structural unit or a liquid crystal aligning agent containing an imidized polymer of the polyimide precursor on the substrate With respect to, polarized radiation is irradiated, and then at least two kinds of solvents having a specific range of boiling points are selected, and at least two kinds of solvents are used in a specific order to be subjected to contact treatment such as dipping, and then to 150 ° C or higher. It has been found that the above object can be achieved by a liquid crystal alignment film obtained by heat treatment.

Thus, 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 and fired on a substrate The resulting film was irradiated with polarized radiation, and then contacted with an organic solvent having a boiling point of 110 to 180 ° C, followed by contact treatment with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C, and then heated at 150 ° C or higher. A method for producing a liquid crystal alignment film, characterized in that it is treated.

[Formula 1]

(X ₁ is a structure represented by the following formula (XA-1).

Y ₁ is a divalent organic group, and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

[Formula 2]

(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.)

2. After irradiating the polarized radiation, the organic solvent having a boiling point of 110 to 180 ° C. and water or a mixed solvent of a water-soluble organic solvent having a boiling point of 50 to 105 ° C. are treated, and then water or boiling point of 50 to 105 ° C. The manufacturing method of the liquid crystal aligning film of said 1 which heat-processes at 150 degreeC or more after contact-processing with a water-soluble organic solvent which has a.

3. The organic solvent having the boiling point of 110 to 180 ° C is represented by the following formulas (A-1), (A-2), (A-3), (A-4) and (A-5). The manufacturing method of the liquid crystal aligning film as described in said 1 or 2 which is at least 1 sort (s) selected from the group which consists.

[Formula 3]

(In formula (A-1), A ₁ is a hydrogen atom or an acetyl group, A ₂ is an alkyl group having 1 to 6 carbon atoms, R ₂ is a hydrogen atom or a methyl group, and n is an integer of 1 or 2 (整數) to be.

In Formula (A-2), A ₃ is an alkyl group having 1 to 4 carbon atoms.

In Formula (A-3), R ₃ and R ₄ are each independently a hydrogen atom or a methyl group.

In Formula (A-4), A ₅ and A ₆ are each independently an alkyl group having 1 to 4 carbon atoms.

In Formula (A-5), A ₆ is an alkyl group having 3 to 6 carbon atoms or a cycloalkyl group.)

4. The organic solvent having the boiling point of 110 to 180 ° C is at least selected from the group consisting of 1-methoxy-2-propanol, ethyl lactate, diacetone alcohol, methyl 3-methoxypropionate and ethyl 3-ethoxypropionate. The manufacturing method of the liquid crystal aligning film in any one of said 1-3 which is 1 type.

5. The manufacturing method of the liquid crystal aligning film in any one of said 1-4 which is at least 1 sort (s) selected from the group which consists of methanol, ethanol, 2-propanol, and acetone.

6. Among the above 1 to 5, wherein the mixed solvent contains an organic solvent having a boiling point of 110 to 180 ° C and a water-soluble organic solvent having a boiling point of 50 to 105 ° C in a mass ratio of 95/5 to 5/95. The manufacturing method of the liquid crystal aligning film in any one.

7. The said 1-6 which is at least 1 sort (s) selected from the group which consists of the polyimide precursor which contains 60 mol% or more with respect to 1 mol of all polymers, and the imidized polymer of the polyimide precursor. The manufacturing method of the liquid crystal aligning film in any one of.

8. In the 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), wherein the liquid crystal alignment film according to any one of 1 to 7 above. Manufacturing method.

[Formula 4]

9. In said Formula (1), the manufacturing method of the liquid crystal aligning film in any one of said 1-8 whose Y <_1> is at least 1 sort (s) selected from the group which consists of a structure represented by following formula (4) and (5).

[Formula 5]

(In formula (5), Z ₁ is a single bond, an ester bond, an amide bond, a thioester bond, or a divalent organic group having 2 to 10 carbon atoms.)

10. In the formula (1), Y ₁ is at least one kind of structure selected from the structures represented by the formula (4) and the following formula (Y1-1), the liquid crystal alignment film according to any one of 1 to 9 above. Manufacturing method.

[Formula 6]

11. The liquid crystal aligning film obtained by the manufacturing method of the liquid crystal aligning film in any one of said 1-10.

12. A liquid crystal display device comprising the liquid crystal alignment film according to 11 above.

When the liquid crystal aligning film obtained by 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.

In the liquid crystal alignment film obtained by the present invention, it is not always clear why the problem of the present invention is solved, but according to the studies of the present inventors, the following has been found. That is, as can be seen from the contrast between Examples and Comparative Examples to be described later, in the present invention, polarized radiation was irradiated to a film obtained by applying and firing a liquid crystal aligning agent using a polyimide precursor having a specific structure on a substrate. For the contact treatment with a solvent to be performed later, the contact treatment with an organic solvent having a boiling point of 110 to 180 ° C and a contact treatment with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C are performed in this order. It was found that it was necessary and the above-mentioned effect was not obtained in either treatment.

In general, it is known that an afterimage caused by alternating current generated in a liquid crystal display device of an IPS driving method or an FFS driving method can be suppressed by increasing the anisotropy of the liquid crystal alignment film and / or by increasing the interaction between the liquid crystal alignment film and the liquid crystal. In the case of the present invention, the foreign matter generated in the process of irradiating polarized radiation previously performed is completely removed by contact processing performed in a specific order using the above-mentioned specific at least two kinds of solvents, and further continues As a result of the reorientation of the molecular chains constituting the remaining liquid crystal alignment film by the heat treatment under specific conditions to be carried out, the anisotropy of the liquid crystal alignment film is increased, and the interaction between the liquid crystal alignment film and the liquid crystal is enhanced. It is thought to be achieved.

<Polyimide and precursor of polyimide>

The liquid crystal aligning agent used in the present invention contains 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.

[Formula 7]

In formula (1), X ₁ is a structure represented by the following formula (XA-1), Y ₁ is a divalent organic group, and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[Formula 8]

In Formula (XA-1), 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 .

Among them, from the viewpoint of liquid crystal alignment, R ₃ , R ₄ , R ₅ and R ₆ are each independently preferably a hydrogen atom, a halogen atom, a methyl group or an ethyl group, and more preferably a hydrogen atom or a methyl group. X ₁ is more preferably at least one member selected from the group consisting of structures represented by the following formulas (X1-1) and (X1-2).

[Formula 9]

Y ₁ is a divalent organic group, and the structure is not particularly limited. Since the anisotropy of the obtained liquid crystal aligning film is high, it is preferable that it is at least 1 sort (s) selected from the group which consists of the structure represented by following formula (Y1-1) and (Y1-2).

[Formula 10]

In Formula (5), Z ₁ is a single bond, an ester bond, an amide bond, a thioester bond, or a divalent organic group having 2 to 10 carbon atoms.

In Z ₁ , the ester bond is represented by -C (O) O- or -OC (O)-. As an amide bond, the structure represented by -C (O) NH-, -C (O) NR-, -NHC (O)-or -NRC (O)-can be shown. Here, R is a C1-C10 alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a group combining these.

Specific examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, t-butyl group, hexyl group, octyl group, cyclopentyl group, cyclohexyl group, and bicyclohexyl group.

Examples of the alkenyl group include those in which one or more CH ₂ -CH ₂ structures present in the alkyl group are replaced with a CH = CH structure, and more specifically, vinyl group, allyl group, 1-propenyl group, and isopro. And phenyl groups, 2-butenyl groups, 1,3-butadienyl groups, 2-pentenyl groups, 2-hexenyl groups, cyclopropenyl groups, cyclopentenyl groups, and cyclohexenyl groups.

Examples of the alkynyl group include those in which one or more CH ₂ -CH ₂ structures present in the alkyl group are substituted with a C≡C structure, and more specifically, ethynyl group, 1-propynyl group, 2-propynyl group, and the like. Can be mentioned.

As an aryl group, a phenyl group is mentioned, for example.

As a thioester bond, the structure represented by -C (O) S- or -SC (O)-can be shown.

When Z ₁ is an organic group having 2 to 10 carbon atoms, the structure can be represented by the following formula (6).

[Formula 11]

In formula (6), Z ₄ , Z ₅ and Z ₆ are each independently a single bond, -O-, -S-, -NR _11- , ester bond, amide bond, thioester bond, urea bond, carbonate Bond or carbamate bond. Here, R ₁₁ is a hydrogen atom, a methyl group or a t-butoxycarbonyl group.

Z _4, for an ester bond, an amide bond and a thioester bond in the Z ₅ and Z _6, may indicate the ester bond, an amide bond and a thioester bond with the same structure.

As a urea bond, the structure represented by -NH-C (O) NH- or -NR-C (O) NR- can be shown. R is a C1-C10 alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a group of these combinations, and these groups include the same examples as the alkyl group, alkenyl group, alkynyl group, and aryl group.

As a carbonate bond, the structure represented by -O-C (O) -O- can be shown.

As a carbamate bond, the structure represented by -NH-C (O) -O-, -OC (O) -NH-, -NR-C (O) -O- or -OC (O) -NR- Can be represented. Here, R is a C1-C10 alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a group of these combinations, and these groups include the same examples as the alkyl group, alkenyl group, alkynyl group, and aryl group.

R ₉ and R ₁₀ in formula (6) are structures independently selected from a single bond, an alkylene group having 1 to 10 carbon atoms, an alkenylene group, an alkynylene group, an arylene group, or a combination of these. When any one of R ₉ and R ₁₀ is a single bond, any of R ₉ or R ₁₀ is a structure selected from a group having 2 to 10 carbon atoms, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, or a combination thereof. to be.

As said alkylene group, the structure remove | excluding one hydrogen atom from the said alkyl group is mentioned. More specifically, methylene group, 1,1-ethylene group, 1,2-ethylene group, 1,2-propylene group, 1,3-propylene group, 1,4-butylene group, 1,2-butylene group, 1,2-pentylene group, 1,2-hexylene group, 2,3-butylene group, 2,4-pentylene group, 1,2-cyclopropylene group, 1,2-cyclobutylene group, 1,3-cyclo And a butylene group, 1,2-cyclopentylene group, and 1,2-cyclohexylene group.

As an alkenylene group, the structure remove | excluding one hydrogen atom from the said alkenyl group is mentioned. More specifically, 1,1-ethenylene group, 1,2-ethenylene group, 1,2-ethenylenemethylene group, 1-methyl-1,2-ethenylene group, 1,2-ethenylene-1 , 1-ethylene group, 1,2-ethenylene-1,2-ethylene group, 1,2-ethenylene-1,2-propylene group, 1,2-ethenylene-1,3-propylene group, 1, 2-ethenylene-1,4-butylene group, 1,2-ethenylene-1,2-butylene group, etc. are mentioned.

As an alkynylene group, the structure remove | excluding one hydrogen atom from the said alkynyl group is mentioned. More specifically, ethynylene group, ethynylenemethylene group, ethynylene-1,1-ethylene group, ethynylene-1,2-ethylene group, ethynylene-1,2-propylene group, ethynylene-1,3 -Propylene group, ethynylene-1,4-butylene group, ethynylene-1,2-butylene group, etc. are mentioned.

As an arylene group, the structure remove | excluding one hydrogen atom from the said aryl group is mentioned. More specifically, 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, etc. are mentioned.

When Y ₁ contains a highly linear structure or a rigid structure, a liquid crystal aligning film having good liquid crystal alignment properties is obtained, so that the structure of Z ₁ is a single bond or the following formulas (A1-1) to (A1-). The structure of 25) is more preferable.

[Formula 12]

[Formula 13]

[Formula 14]

[Formula 15]

As the structure of Y ₁ , the formula (4) or the following formula (Y1-1) is particularly preferable because the removal property of the decomposed product according to the contact treatment with the solvent is good and the liquid crystal alignment is excellent.

[Formula 16]

In the polyimide precursor containing the structural unit represented by the formula (1) and the imidized polymer of the polyimide precursor, the proportion of the structural unit represented by the formula (1) is 60 to 1 mole of the total structural units in the total polymer -100 mol% is preferable. Since the liquid crystal aligning film which has favorable liquid crystal alignability is obtained, so that the ratio of the structural unit represented by said Formula (1) is high, 80-100 mol% is more preferable, and 90-100 mol% is still more preferable.

The polymer component of the present invention may be a polyimide precursor containing the structural unit represented by the following formula (7) and a polyimide precursor thereof in addition to the structural unit represented by the formula (1).

[Formula 17]

In Formula (7), R ₁ is the same definition as R _{1 in} Formula (1).

X ₃ is a tetravalent organic group, and its structure is not particularly limited. When specific examples are listed, the structures of the following formulas (X-1) to (X-42) are exemplified. From the viewpoint of compound availability, the structure of X ₃ is preferably X-17, X-25, X-26, X-27, X-28, X-32 or X-39. Moreover, it is preferable to use a tetracarboxylic dianhydride having an aromatic ring structure from the viewpoint of obtaining a liquid crystal alignment film having a fast relaxation of residual charges accumulated by a direct current voltage, and X-26, X as the structure of X ₃ -27, X-28, X-32, X-35 or X-37 is more preferable.

[Formula 18]

[Formula 19]

[Formula 20]

[Formula 21]

[Formula 22]

In the formula (7), Y ₄ is a divalent organic group, and its structure is not particularly limited. And if there are any specific examples of Y ₄ example, there may be mentioned a structure of the formula (Y-1) ~ (Y -74).

[Formula 23]

[Formula 24]

[Formula 25]

[Formula 26]

[Formula 27]

Since the solubility of the polymer component in the organic solvent is excellent, as Y ₄ in the formula (7), Y-8, Y-20, Y-21, Y-22, Y-28, Y-29, Y- It is preferable to contain a structural unit having a structure of 30, Y-72, Y-73 or Y-74.

When the proportion of the structural unit represented by the formula (7) in the polymer component is high, the liquid crystal alignment of the liquid crystal alignment film is lowered, so the proportion of the structural unit represented by the formula (7) is 0 to 1 mol of the total structural units -40 mol% is preferable, and 0-20 mol% is more preferable.

<Method for producing polyamic acid ester>

In the case of the polyamic acid ester used as the polyimide precursor used in the present invention, the polyamic acid ester 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 terms of solubility of the polymer, and these are mixed in one or more types You may use it.

The polymer concentration in the organic solvent during synthesis is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, in order to prevent precipitation of the polymer easily and to easily obtain a high molecular weight body.

(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 are in the presence of a base and an organic solvent at -20 to 150 ° C, preferably 0 to 50 ° C, for 30 minutes to 24 hours, preferably 1 to 4 hours. It can synthesize | combine by making time reaction.

As the base, pyridine, triethylamine, 4-dimethylaminopyridine, or the like can be used, but pyridine is preferable for the reaction to proceed smoothly. The amount of the base added is an amount that is easily removed, and in order to easily obtain a high molecular weight body, it is preferably 2 to 4 times mole, more preferably 2 to 3 times mole to tetracarboxylic acid diester dichloride.

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

The polymer concentration in the organic solvent during synthesis is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, in order to prevent precipitation of the polymer easily and to easily obtain a high molecular weight body. In addition, in order to prevent the hydrolysis of the tetracarboxylic acid diester dichloride, it is preferable that the organic solvent used in 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 preferred.

(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 hours It can be synthesized by reacting.

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. The amount of the condensing agent added is preferably 2 to 3 times mole, more preferably 2 to 2.5 times mole, relative to the tetracarboxylic acid diester.

As the base, tertiary amines such as pyridine and triethylamine can be used. The amount of the base added is an amount that can be easily removed, and in order to easily obtain a high molecular weight substance, 2 to 4 times mole is preferable, and 2 to 3 times mole is preferable with respect 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 Lewis acid to be 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 an empty 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>

When the polyimide precursor used in the present invention is polyamic acid, the polyamic acid can be synthesized by the method shown below.

Specifically, it is synthesized by reacting tetracarboxylic dianhydride with 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 1 to 30% by mass, more preferably 5 to 20% by mass, in order to easily precipitate a polymer and to easily obtain a high molecular weight.

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 a polyamic acid ester or polyamic acid which is a precursor of the polyimide.

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 carried out 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 for 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 in the reaction of the diamine component and tetracarboxylic dianhydride. Chemical imidization 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 process of imidization.

Chemical imidation can be carried out 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. Moreover, acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. are mentioned as an acid anhydride. Especially, if acetic anhydride is used, purification after completion | finish of reaction becomes easy, and it is preferable.

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 for 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 polyamic acid, the imidized polymer obtained by the means described below is recovered, and redissolved in an organic solvent to obtain a liquid crystal aligning agent of the present invention. It is desirable to do.

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 in that a uniform and defect-free coating film is formed. It is preferable to set it as 10 mass% or less from a stability viewpoint. 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 the coating film uniformity when the liquid crystal aligning agent is applied to the substrate. In general, a low surface tension solvent is used as the solvent. 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.

In 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 and 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 WHEREIN: The film obtained by apply | coating and baking a liquid crystal aligning agent to a board | substrate is the process of irradiating polarized radiation, and the film irradiated with radiation, with the organic solvent which has a boiling point of 110-180 degreeC. It has a process of contact treatment, and then a process of contact treatment with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C, and a process of heating the contact-treated film at 150 ° C or higher. Hereinafter, each process is demonstrated.

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

A polyimide film or a film in which a polyimide precursor is imidized 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, and a material that reflects light such as aluminum can also be used for the electrode in this case.

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.

The drying and firing process after applying the liquid crystal aligning agent can select any temperature and time. 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, the 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

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

As a specific example of a photo-alignment process, the method of irradiating the surface of the said coating film with the polarized radiation in a predetermined direction, and providing the liquid crystal aligning ability is mentioned. As the wavelength of the radiation, ultraviolet rays or visible rays having a wavelength of 100 to 800 nm can be used. Among these, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and those having a wavelength of 200 to 400 nm are particularly preferable.

The radiation dose is preferably in the range of 1 to 10,000 mJ / cm 2, particularly preferably in the range of 100 to 5,000 mJ / cm 2. The temperature for irradiating polarized radiation to the film is preferably carried out at 10 to 100 ° C, and particularly preferably 20 to 50 ° C.

(3) Process of contact treatment with solvent

In the step (2), the film irradiated with polarized radiation is contact-treated using two specific solvents. For the contact treatment, at least two kinds of solvents having an organic solvent having a boiling point of 110 to 180 ° C, preferably 115 to 160 ° C, and water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C, preferably of 50 to 80 ° C Is used.

Moreover, using these two types of solvents means using at least these two types of solvents, and also using the solvents containing other solvents together with these two types of solvents. Moreover, in addition to the contact processing with these two types of solvents, you may perform contact processing using solvents other than these two types.

Examples of the organic solvent having the boiling point of 110 to 180 ° C include the following groups (A-1), (A-2), (A-3), (A-4) and (A-5). At least one organic solvent selected is preferred.

[Formula 28]

In Formula (A-1), A ₁ is a hydrogen atom or an acetyl group, A ₂ is an alkyl group having 1 to 6 carbon atoms, R ₂ is a hydrogen atom or a methyl group, and n is an integer of 1 or 2.

In Formula (A-2), A ₃ is an alkyl group having 1 to 4 carbon atoms.

In Formula (A-3), R ₃ and R ₄ are each independently a hydrogen atom or a methyl group.

In Formula (A-4), A ₅ and A ₆ are each independently an alkyl group having 1 to 4 carbon atoms.

In Formula (A-5), A ₆ is an alkyl group having 3 to 6 carbon atoms or a cycloalkyl group.

The organic solvents of the formulas (A-1) to (A-5) are, among others, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate , Diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, at least one selected from the group consisting of propyl acetate, butyl acetate and cyclohexyl acetate is preferred. In particular, at least one member selected from the group consisting of 1-methoxy-2-propanol and ethyl lactate is preferable.

Moreover, preferable examples of the water or water-soluble organic solvent having a boiling point of 50 to 105 ° C include water, methanol, ethanol, 2-propanol, and acetone. Especially, water and 2-propanol are more preferable.

In the present invention, the contact treatment using a film irradiated with polarized radiation and two types of solvent is performed by a treatment in which the film and the liquid are preferably sufficiently contacted, such as immersion treatment and spray (spray) treatment. Especially, the method of immersing a film in a solvent, Preferably 10 second-1 hour, More preferably, 1-30 minutes is preferable. The contact treatment may be performed at room temperature or higher or lower by controlling the temperature of the film or solvent, but is preferably carried out at 10 to 80 ° C, more preferably 20 to 50 ° C. Moreover, if necessary, means for increasing the contact such as agitation or ultrasonic waves can be implemented.

When the organic solvent having a boiling point of 110 to 180 ° C, followed by water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C is sequentially contacted, both of the contacting treatments may be carried out continuously or over time. In the latter case, it is not preferable to add too much time, so it is preferable to carry out continuously.

On the other hand, in the case of contact treatment with an organic solvent having a boiling point of 110 to 180 ° C. and a mixed solvent containing water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C., the mixed solvent is an organic having a boiling point of 110 to 180 ° C. It is preferable to contain the solvent and water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C in a mass ratio of preferably 95/5 to 5/95, more preferably 95/5 to 50/50.

(4) Heating at 150 ° C or higher

The film subjected to the contact treatment using two kinds of solvent is then heat-treated at a temperature of 150 ° C or higher. You may perform such heat processing after drying the contact-treated film using a solvent. The drying of the membrane is preferably 80 to 150 ° C. The drying time is preferably 10 seconds to 30 minutes.

The temperature of the heat treatment is preferably 150 to 300 ° C. The higher the temperature, the faster the reorientation of the molecular chain, but if the temperature is too high, there is a fear that the decomposition of the molecular chain. Therefore, 180-250 degreeC is more preferable as heating temperature, and 200-230 degreeC is especially preferable.

When the heating time is too short, the effect of the present invention may not be obtained, and if too long, the molecular chain may decompose, and thus 10 seconds to 30 minutes is preferable, and 1 to 10 minutes are more preferable.

<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 the liquid crystal aligning agent, it manufactures a liquid crystal cell by a well-known method, and uses the liquid crystal cell to display a liquid crystal. It was made as a device.

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, 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 to display desired images. Subsequently, an insulating film is formed on each substrate by covering the common electrode and the segment electrode. 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 surfaces of the alignment films face each other, and the periphery is bonded with a sealing material. In order to control the substrate gap, a spacer is usually incorporated in the sealing material. In addition, it is preferable to distribute the spacer for controlling the substrate gap in the in-plane portion where the sealing material is not formed. 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 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 attached to a surface opposite to the liquid crystal layer of the two-substrate substrate. 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 this invention as a liquid crystal aligning film, it becomes the thing with excellent afterimage property, and can be used suitably for a high resolution liquid crystal television etc. on a large screen.

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 abbreviations of the compounds used in Examples and Comparative Examples and the method for measuring each property are as follows.

NMP: N-methyl-2-pyrrolidone

GBL: γ-butyrolactone

BCS: Butyl Cellosolve

IPA: 2-propanol

DA-2: Formula (DA-2) (Boc group represents a t-butoxycarbonyl group)

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

[Formula 29]

Below, the method of viscosity, molecular weight, imidation rate, liquid crystal cell manufacture, and afterimage evaluation by long-term AC drive are shown.

[Viscosity]

In the synthesis example, the viscosity of the polyamic acid ester and the polyamic acid solution was 1.1 ml of sample volume using an E-type viscometer TVE-22H (manufactured by Toki Sangyo), cone rotor TE-1 (1 ° 34 kPa, 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 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 (as an additive, lithium bromide-hydrate (LiBrH ₂ O) is 30 mmol / L (liters), phosphoric acid / anhydrous crystals (o-phosphoric acid) is 30 mmol / L, Tetrahydrofuran (THF) is 10 ml / ℓ)

Flow rate: 1.0 ml / min

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

[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.). In the imidation ratio, the proton derived from a structure that does not change before and after imidization is defined as a reference proton, and the peak integrated value of this proton and the proton peak integration derived from the NH group of the amide acid appearing around 9.5 ppm to 10.0 ppm. The value was used to obtain the following equation.

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.

Initially, an electrode-attached 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 printed pattern, which constitutes a counter electrode as a first layer, is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by a CVD (Chemical Vapor Deposition) method is formed as the second layer. 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 long and about 5 mm wide. 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 curved U-shaped electrode elements in the central portion, 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. Then, each pixel is divided up and down with the center of the curved portion as a boundary, and has an upper first region and a lower second region of the curved portion.

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 direction of the rotation operation (in-plane switching) in the substrate surface of the liquid crystal caused 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 obtained liquid crystal aligning agent with a filter of 1.0 μm, spin coating is applied to a glass substrate having a 4 μm height columnar spacer on which the prepared electrode is attached and an ITO film is formed on the back surface. Applied. After drying for 5 minutes on a hot plate at 80 ° C, baking was performed for 20 minutes in a hot air circulation type oven at 230 ° C to form a coating film having a film thickness of 100 nm. The surface of this coating film was irradiated with ultraviolet rays having a wavelength of 254 nm linearly polarized with an extinction ratio of 10: 1 or higher through a polarizing plate. This substrate was immersed for 3 minutes in an organic solvent having a boiling point of 110 to 180 ° C, or a mixed solvent containing an organic solvent having a boiling point of 110 to 180 ° C and water or an organic solvent having a boiling point of 50 to 105 ° C, followed by pure water. It was immersed for 1 minute and heated on a hot plate at 150 to 300 ° C for 5 minutes to obtain a substrate with a liquid crystal alignment film. The above two substrates are set as one set, a sealing agent is printed on the substrate, and the other one substrate is attached with the liquid crystal alignment film faces facing each other so that the orientation direction is 0 °, and then the sealing agent is cured to empty cells. Was prepared. 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, 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. In the second pixel, the same angle Δ was calculated by comparing the second region and the first region. 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)

In a 3000 ml 4-necked flask with a stirring device and nitrogen introduction tube, 1,2-bis (4-aminophenoxy) ethane was added to 124.60 g (510 mmol) and DA-2 0.95 g (90.0 mmol), 2236 g of NMP was added and dissolved while stirring with nitrogen. While stirring this diamine solution, 130.06 g (580.2 mmol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was added, and NMP was further added so that the solid content concentration was 10% by mass. 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 2)

200 g of the obtained polyamic acid solution (PAA-2) was added to a 500 ml four-necked flask with a stirring device and nitrogen introduction tube, and 85.68 g of NMP was added, 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.

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 dissolved with stirring at room temperature for 24 hours to obtain a polyimide solution (PI-1).

(Synthesis Example 3)

59.59 g of the polyimide solution (PI-1) obtained in Synthesis Example 2 was added to a 200 ml sample tube containing a stirrer, and 0.317% by mass of an NMP solution of 3-glycidoxypropylmethyldiethoxysilane was 7.17 g, NMP was 11.26. g, 26.0 g of BCS and 2.08 g of additive A were added, and stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (AL-1).

<Example 1>

After filtering the liquid crystal aligning agent (AL-1) obtained in Synthesis Example 3 with a 1.0 µm filter, the prepared substrate having the electrode attached thereto and a glass having a columnar spacer having a height of 4 µm with an ITO film formed thereon were formed. The substrate was applied by spin coating. After drying for 5 minutes on a hot plate at 80 ° C, baking was performed for 20 minutes in a hot air circulation type oven at 230 ° C to form a coating film having a film thickness of 100 nm. At room temperature (25 ° C.), 0.2 J / cm 2 of ultraviolet light having a wavelength of 254 nm linearly polarized with an extinction ratio of 26: 1 was irradiated to the surface of the coating film through a polarizing plate. This substrate was immersed in ethyl lactate for 3 minutes at room temperature, then immersed in pure water for 1 minute, and heated on a hot plate at 200 ° C for 5 minutes to obtain a substrate with a liquid crystal alignment film. The above two substrates are set as one set, a sealing agent is printed on the substrate, and the other one substrate is attached with the liquid crystal alignment film faces facing each other so that the orientation direction is 0 °, and then the sealing agent is cured to empty cells. Was prepared. 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 0.06 degrees.

<Example 2>

Example 1, except that after irradiating polarized ultraviolet light to the coated film surface of the substrate, the substrate was immersed in ethyl lactate for 3 minutes at room temperature, then immersed in pure water for 1 minute, and heated on a hot plate at 230 ° C for 1 minute. FFS-driven liquid crystal cell was manufactured in the same manner as. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.04 degrees.

<Example 3>

Example 1, except that after irradiating polarized ultraviolet light on the coated film surface of the substrate, the substrate was immersed in ethyl lactate for 3 minutes at room temperature, then immersed in pure water for 1 minute, and heated on a hot plate at 230 ° C for 3 minutes. FFS-driven liquid crystal cell was manufactured in the same manner as. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term alternating current driving was 0.03 degrees.

<Example 4>

Example 1, except that after irradiating polarized ultraviolet light on the coated film surface of the substrate, the substrate was immersed in ethyl lactate for 3 minutes at room temperature, then immersed in pure water for 1 minute, and heated on a hot plate at 230 ° C for 5 minutes. FFS-driven liquid crystal cell was manufactured in the same manner as. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term alternating current driving was 0.03 degrees.

<Example 5>

Example 1, except that after irradiating polarized ultraviolet rays on the coated film surface of the substrate, the substrate was immersed in ethyl lactate for 3 minutes at room temperature, then immersed in pure water for 1 minute, and heated on a hot plate at 230 ° C for 10 minutes. FFS-driven liquid crystal cell was manufactured in the same manner as. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.04 degrees.

<Example 6>

After irradiating polarized ultraviolet rays on the coated film surface of the substrate, the substrate was immersed in ethyl lactate and IPA in a mixed solvent (mass ratio: ethyl lactate / IPA = 50/50) for 3 minutes at room temperature, and then immersed in pure water for 1 minute. , FFS-driven liquid crystal cell was manufactured in the same manner as in Example 1, except that it was heated for 5 minutes on a hot plate at 230 ° C. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term alternating current driving was 0.03 degrees.

<Example 7>

After irradiating polarized ultraviolet light to the coated film surface of the substrate, the substrate was immersed in ethyl lactate and pure water in a mixed solvent (mass ratio: ethyl lactate / pure water = 85/15) at 20 ° C for 3 minutes, and then immersed in pure water for 1 minute. And the FFS-driven liquid crystal cell was manufactured in the same manner as in Example 1, except that it was heated on a hot plate at 230 ° C for 5 minutes. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.09 degrees.

<Comparative Example 1>

After filtering the liquid crystal aligning agent (AL-1) obtained in Synthesis Example 3 with a 1.0 µm filter, the prepared substrate having the electrode attached thereto and a glass having a columnar spacer having a height of 4 µm with an ITO film formed thereon were formed. The substrate was applied by spin coating. The coated substrate was heated on a hot plate at 80 ° C for 5 minutes, and then calcined for 20 minutes in a hot air circulation oven at 230 ° C to form a coated film having a film thickness of 100 nm. At room temperature, 0.2 J / cm 2 of ultraviolet light having a wavelength of 254 nm linearly polarized with an extinction ratio of 26: 1 was irradiated onto the surface of the coating film through a polarizing plate. The substrate was heated on a hot plate at 230 ° C for 20 minutes to obtain a substrate with a liquid crystal alignment film. The above two substrates are set as one set, a sealing agent is printed on the substrate, and the other one substrate is attached with the liquid crystal alignment film faces facing each other so that the orientation direction is 0 °, and then the sealing agent is cured to empty cells. Was prepared. 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 3.0 degrees.

<Comparative Example 2>

Example 1, except that after irradiating polarized ultraviolet light on the coated film surface of the substrate, the substrate was immersed in ethyl lactate for 3 minutes at room temperature, then immersed in pure water for 1 minute, and heated on a hot plate at 80 ° C for 5 minutes. FFS-driven liquid crystal cell was manufactured in the same manner as. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.10 degrees.

<Comparative Example 3>

After irradiating polarized ultraviolet light on the coated film surface of the substrate, the substrate was immersed in a mixed solvent of ethyl lactate and IPA (mass ratio: ethyl lactate / IPA = 50/50) for 3 minutes at room temperature, and then immersed in pure water for 1 minute. , A FFS-driven liquid crystal cell was manufactured in the same manner as in Example 1, except that it was heated for 5 minutes on a hot plate at 80 ° C. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The angle Δ value of this liquid crystal cell after long-term AC driving was 0.12 degrees.

<Comparative Example 4>

After irradiating polarized ultraviolet light on the coated film surface of the substrate, the substrate was immersed in a mixed solvent of ethyl lactate and pure water (mass ratio: ethyl lactate / pure water = 85/15) at room temperature for 3 minutes, and then immersed in pure water for 1 minute. , A FFS-driven liquid crystal cell was manufactured in the same manner as in Example 1, except that it was heated for 5 minutes on a hot plate at 80 ° C. Afterimage evaluation by long-term AC drive was performed for this FFS-driven liquid crystal cell. The angle Δ value of this liquid crystal cell after long-term AC driving was 0.48 degrees.

Industrial availability

The liquid crystal aligning film obtained from the liquid crystal aligning agent of this invention can reduce the afterimage by AC drive generated in the liquid crystal display element of IPS drive method or FFS drive method, and the IPS drive method or FFS drive method liquid crystal excellent in afterimage characteristics A 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 content of the specification, the claims, and the abstract of Japanese Patent Application No. 2012-263386, filed on November 30, 2012, is cited herein, and accepted as the disclosure of the specification of the present invention.

Claims (12)

Film 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 the following formula (1) and an imidized polymer of the polyimide precursor Then, after irradiating the polarized radiation, contact treatment with an organic solvent having a boiling point of 110 to 180 ° C, followed by contact treatment with water or a water-soluble organic solvent having a boiling point of 50 to 105 ° C, followed by heat treatment at 150 ° C or higher A method for producing a liquid crystal alignment film, characterized in that.
[Formula 1]

(X ₁ is a structure represented by the following formula (XA-1).
Y ₁ is a divalent organic group, and R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)
[Formula 2]

(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.) According to claim 1,
After irradiating the polarized radiation, the organic solvent having a boiling point of 110 to 180 ° C. and water or a mixed solvent of a water-soluble organic solvent having a boiling point of 50 to 105 ° C. are treated, and then water or water-soluble having a boiling point of 50 to 105 ° C. The manufacturing method of the liquid crystal aligning film which heat-processes at 150 degreeC or more after contact-processing with an organic solvent. According to claim 1,
The organic solvent having the boiling point of 110 to 180 ° C. is composed of the following formulas (A-1), (A-2), (A-3), (A-4), and (A-5). Method for producing a liquid crystal alignment film that is at least one selected from.
[Formula 3]

(In formula (A-1), A ₁ is a hydrogen atom or an acetyl group, A ₂ is a C 1-6 alkyl group, R ₂ is a hydrogen atom or a methyl group, and n is an integer of 1 or 2.
In Formula (A-2), A ₃ is an alkyl group having 1 to 4 carbon atoms.
In Formula (A-3), R ₃ and R ₄ are each independently a hydrogen atom or a methyl group.
In Formula (A-4), A ₅ and A ₆ are each independently an alkyl group having 1 to 4 carbon atoms.
In Formula (A-5), A ₆ is an alkyl group having 3 to 6 carbon atoms or a cycloalkyl group.) According to claim 1,
The organic solvent having the boiling point of 110 to 180 ° C is at least one member selected from the group consisting of 1-methoxy-2-propanol, ethyl lactate, diacetone alcohol, methyl 3-methoxypropionate and ethyl 3-ethoxypropionate. Method for manufacturing a liquid crystal alignment film. According to claim 1,
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 2,
The said mixed solvent contains the organic solvent which has a boiling point of 110-180 degreeC, and the water-soluble organic solvent which has water or a boiling point of 50-105 degreeC by 95 / 5-5 / 95 by mass ratio, The manufacturing method of the liquid crystal aligning film. According to claim 1,
The manufacturing method of the liquid crystal aligning film which is at least 1 sort (s) selected from the group which consists of a polyimide precursor containing the structural unit represented by said Formula (1) 60 mol% or more with respect to 1 mol of all polymers, and an imidized polymer of the polyimide precursor. According to claim 1,
In the formula _(1), X 1 is the following formula, at least one type method for producing a liquid crystal alignment layer is selected from the group consisting of structures represented by (X1-1) and (X1-2).
[Formula 4]

According to claim 1,
The formula (1), wherein, Y ₁ is the following formula (4) and at least one member manufacturing method of the liquid crystal alignment layer is selected from the group consisting of structures shown by (5) a.
[Formula 5]

(In formula (5), Z ₁ is a single bond, an ester bond, an amide bond, a thioester bond, or a divalent organic group having 2 to 10 carbon atoms.) The method of claim 9,
In the formula _(1), Y 1 is the formula (4) and the following formula The method of liquid crystal alignment film, at least one kind of structure selected from the structures represented by (Y1-1).
[Formula 6]

The liquid crystal aligning film obtained by the manufacturing method of the liquid crystal aligning film in any one of Claims 1-10. The liquid crystal display element provided with the liquid crystal aligning film of Claim 11.