KR101848962B1 - Liquid crystal orientation agent for photo-orientation treatment method and liquid crystal orientation film using same - Google Patents

Abstract

A liquid crystal aligning agent suitable for a photo alignment treatment method capable of suppressing afterimage due to AC driving generated in an IPS driving method or an FFS driving type liquid crystal display element and a liquid crystal alignment film obtained from the liquid crystal alignment agent.
A polyamic acid (component (A)) obtained by a polycondensation reaction of a tetracarboxylic acid dianhydride having a specific structure having a cyclobutane skeleton and a diamine compound having a highly linear diamine compound represented by p-phenylenediamine, An imidazole derivative (component (B)) having an alkyl group of 3 to 10 carbon atoms or an alkenyl group, and a liquid crystal aligning agent for an optical alignment treatment method containing an organic solvent.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal aligning agent for use in a photo-alignment treatment method, and a liquid crystal alignment film using the liquid crystal aligning film. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a liquid crystal aligning agent for producing a liquid crystal alignment film, and a liquid crystal alignment film obtained from the liquid crystal aligning agent. More specifically, the present invention relates to a liquid crystal aligning agent suitable for a photo-alignment treatment method, that is, a photo-alignment treatment method for imparting liquid crystal aligning ability by irradiation of polarized ultraviolet ray, and a liquid crystal alignment film obtained from such a liquid crystal aligning agent .

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

At present, in the industry's most popular method, this liquid crystal alignment film is formed by laminating the surface of a film made of polyamic acid and / or polyimide, which is formed on the electrode substrate and / or imidized thereon, with a cloth such as cotton, nylon, And rubbing in the direction of the rubbing process.

The rubbing treatment of the film surface in the alignment process of the liquid crystal alignment film is an industrially useful method which is simple and excellent in productivity. However, the demand for higher performance, higher definition, and larger size of liquid crystal display elements is further heightened, and the influence of scratches, oscillations, mechanical force, and static electricity on the surface of the alignment film caused by the rubbing treatment, Various problems such as nonuniformity are becoming clear.

As an alternative to the rubbing treatment, there is known a photo alignment method in which a liquid crystal aligning ability is imparted by irradiating polarized radiation. The liquid crystal alignment treatment by the photo alignment method has been proposed using a photoisomerization reaction, a photo-crosslinking reaction, and a photo-decomposition reaction (see Non-Patent Document 1).

When polyimide is used for a liquid crystal alignment film for optical alignment, its usefulness is expected in view of its high heat resistance as compared with the others. In Patent Document 1, it has been proposed to use a polyimide film having an alicyclic structure such as a cyclobutane ring in the main chain in the photo alignment method.

The above-described photo alignment method is advantageous in that it can be produced by an industrially easy manufacturing process as a rubbing-less alignment processing method, and is also applicable to a liquid crystal display element of an IPS driving method or a fringe field switching (hereinafter, FFS) It is possible to improve the contrast and viewing angle characteristics of the liquid crystal display element as compared with the liquid crystal alignment film obtained by the rubbing treatment method by using the liquid crystal alignment film obtained by the photo alignment method to improve the performance of the liquid crystal display element And is attracting attention as a promising liquid crystal alignment treatment method.

In addition to the basic characteristics such as excellent liquid crystal alignability and electrical characteristics, liquid crystal alignment films used in liquid crystal display devices of the IPS driving method and the FFS driving method are required to have excellent characteristics such as the IPS driving method and the FFS driving liquid crystal display device It is necessary to suppress the afterimage caused by the photoreceptor. However, the liquid crystal alignment film obtained by the photo alignment method is insufficient in alignment control force and stability of the liquid crystal, and it is difficult to satisfy the above characteristics.

Japanese Patent Application Laid-Open No. 9-297313

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

The present invention provides a liquid crystal aligning agent suitable for a photo alignment treatment method capable of suppressing afterimage due to AC driving generated in an IPS driving method or an FFS driving type liquid crystal display device and a liquid crystal aligning agent obtained from the liquid crystal aligning agent .

As a result of intensive research to achieve the above object, the present inventors have found that a tetracarboxylic acid dianhydride having a specific structure having a cyclobutane skeleton and a diamine compound having a high linearity diamine represented by p-phenylenediamine It has been found that the above object can be achieved by a liquid crystal aligning agent containing a polyamic acid obtained from a polycondensation reaction and an imidazole derivative having an alkyl group or alkenyl group having 3 to 10 carbon atoms.

The present invention provides the following aspects.

1. A liquid crystal aligning agent comprising the following components (A), (B) and an organic solvent.

(A): a tetracarboxylic acid dianhydride containing a tetracarboxylic acid dianhydride represented by the following formula (1) in an amount of 60 mol% or more of the total tetracarboxylic acid dianhydride and a diamine compound represented by the following formula (2) And a diamine compound represented by the following formula (3) in an amount of at least 60 mol% of the total diamine compound.

[Chemical Formula 1]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ 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 alkenyl group having 2 to 6 carbon atoms An alkynyl group or a phenyl group, which may be the same or different)

(2)

(In the formula (3), A 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)

Component (B): at least one imidazole derivative selected from the group consisting of the following formulas (B-1) to (B-4).

(3)

(In the formulas (B-1) to (B-4), R ₅ , R ₆ , R ₇ and R ₈ are each independently an alkyl group or an alkenyl group having 3 to 10 carbon atoms)

2. The liquid crystal aligning agent according to 1 above, wherein the content of the component (A) is 1 to 10% by mass.

3. The liquid crystal aligning agent according to 1 or 2 above, wherein the content of the component (B) is 0.1 to 50 parts by mass relative to 100 parts by mass of the component (A).

4. A method for producing the component (A), wherein the tetracarboxylic acid dianhydride represented by the above formula (1) is 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and 1,3- , And at least one tetracarboxylic acid dianhydride selected from the group consisting of 3,4-cyclobutane tetracarboxylic acid dianhydride.

5. The liquid crystal aligning agent according to any one of 1 to 4 above, wherein the diamine compound for obtaining the component (A) is a diamine compound containing at least 60 mol% of the diamine compound represented by the formula (2).

6. The process according to claim 1, wherein the imidazole derivative of component (B) is at least one selected from the group consisting of 1-propylimidazole, 1-allylimidazole, 1-butylimidazole, 2-propylimidazole, and 2-butylimidazole The liquid crystal aligning agent according to any one of 1 to 5 above, which is at least one kind selected.

7. The liquid crystal alignment described in 1 to 5 above, wherein the imidazole derivative of the component (B) is at least one member selected from the group consisting of 1-allylimidazole, 1-propylimidazole and 1-butylimidazole. My.

8. The liquid crystal aligning agent according to any one of 1 to 7 above, wherein the diamine compound for obtaining the component (A) further contains a diamine compound represented by the following formula (DA-1).

[Chemical Formula 4]

9. A liquid crystal alignment film obtained by applying and firing the liquid crystal aligning agent according to any one of 1 to 8 above.

10. A liquid crystal alignment film obtained by coating and firing the liquid crystal aligning agent according to any one of 1 to 8 above, and subsequently irradiating with polarized radiation.

The liquid crystal alignment film of the present invention can reduce the afterimage caused by the AC drive generated in the IPS drive method or the FFS drive type liquid crystal display device and obtain the IPS drive method or the FFS drive method liquid crystal display device excellent in afterimage characteristic.

How the liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention solves the problem of the present invention is not necessarily clarified, but it can be considered as follows.

The polyimide having a cyclobutane ring in the main chain is subjected to a ring-opening reaction of the following formula (i) only in a molecular chain in which the major axis direction of the molecular chain is parallel to the polarization direction, by irradiation with polarized radiation, On the other hand, in the molecular chain in which the major axis direction of the molecular chain is perpendicular to the polarization direction, the reaction of the following formula (i) does not proceed but remains in the film in a state of high molecular weight. As a result, the polyimide film irradiated with the polarized radiation exhibits anisotropy in the direction perpendicular to the polarization direction, and the liquid crystal alignment ability is imparted thereto. The reaction of the following formula (i) proceeds most efficiently when the imide ring is formed. Therefore, when the imidization rate of the film obtained by firing is low, the reaction of the formula (i) below proceeds very slightly, resulting in a film having a small anisotropy. On the other hand, when the imidization rate of the film obtained by firing is high, the reaction of the following formula (i) proceeds sufficiently, and a film having high anisotropy is obtained. In an IPS drive type or FFS drive type liquid crystal display device, the larger the anisotropy of the liquid crystal alignment film is, the higher the liquid crystal alignment property is, and the afterimage due to the AC drive can be suppressed.

[Chemical Formula 5]

The imidazole derivative used in the liquid crystal aligning agent of the present invention can promote the imidization reaction by heating the polyamic acid by coexisting with the polyamic acid. Therefore, the polyimide film obtained by applying and firing the liquid crystal aligning agent of the present invention has a high imidization ratio, and by irradiating with polarized radiation, a film having high anisotropy can be obtained, and a liquid crystal alignment film having high liquid crystal alignability is obtained.

However, even if the additive has a high effect of promoting imidization by heating of the polyamic acid, if the additive remains in the film, the orientation of the liquid crystal is inhibited and the performance of the liquid crystal alignment film is deteriorated. On the other hand, the imidazole derivative used as the liquid crystal aligning agent of the present invention is not only highly effective in promoting imidization by heating of the polyamic acid, but also has a structure that is easily evaporated or sublimated during firing, And does not lower the liquid crystal alignment property.

From the above, it is considered that the liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention has high liquid crystal alignability and can suppress the afterimage due to the AC drive generated in the IPS drive method or the FFS drive type liquid crystal display device.

≪ Component (A) >

The component (A) contained in the liquid crystal aligning agent of the present invention is preferably a tetracarboxylic acid dianhydride containing 60 mol% or more of the tetracarboxylic acid dianhydride represented by the following formula (1) , And diamine compounds represented by the following formulas (2) and (3) with a diamine compound containing at least 60 mol% of the total diamine compound.

[Chemical Formula 6]

(7)

In the formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, Or a phenyl group.

R ₁ , R ₂ , R ₃ and R ₄ are preferably a hydrogen atom, a halogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom or a methyl group, from the viewpoint of liquid crystal alignability.

Specific examples of the tetracarboxylic acid dianhydride having a cyclobutane ring represented by the above formula (1) include the following formulas (1-1) to (1-5). (1-1) or (1-2) is more preferable, and (1-2) is more preferable from the viewpoint of liquid crystal alignability.

[Chemical Formula 8]

In the diamine compound represented by the formula (3), A 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 A ₁ , the ester bond is represented by -C (O) O-, or -OC (O) -. As the amide bond, a structure represented by -C (O) NH- or -C (O) NR-, -NHC (O) - or -NRC (O) - can be disclosed. R is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a combination thereof having 1 to 10 carbon atoms.

Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a cyclopentyl group, a cyclohexyl group and a bicyclohexyl group. Examples of the alkenyl group include those obtained by substituting at least one CH-CH structure present in the alkyl group with a C = C structure, and more specifically, a vinyl group, allyl group, 1-propenyl group, 2-butenyl, 1,3-butadienyl, 2-pentenyl, 2-hexenyl, cyclopropenyl, cyclopentenyl, cyclohexenyl and the like. Examples of the alkynyl group include those wherein at least one CH ₂ -CH ₂ structure existing in the alkyl group is substituted with a C≡C structure. More specifically, an ethynyl group, 1-propynyl group, 2-propynyl group, . The aryl group includes, for example, a phenyl group.

The thioester bond may represent a structure represented by -C (O) S- or -SC (O) -.

When A < _{1 >} is an organic group having 2 to 10 carbon atoms, it may be represented by the following formula (4).

[Chemical Formula 9]

-A ₄ -R ₉ -A ₅ -R ₁₀ -A ₆ - (4)

In formula (4), A ₄ , A ₅ and A ₆ each independently represent a single bond, -O-, -S-, -NR ₁₁ -, an ester bond, an amide bond, a thioester bond, A carbonate bond, or a carbamate bond. R ₁₁ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group or an aryl group, or a combination thereof, and examples of the alkyl group, alkenyl group, alkynyl group and aryl group are mentioned.

The ester bond, amide bond and thioester bond in A ₄ , A ₅ and A ₆ may have the same structure as the ester bond, amide bond and thioester bond.

The urea bond may represent a structure represented by -NH-C (O) NH- or -NR-C (O) NR-. R is an alkyl group, an alkenyl group, an alkynyl group, or an aryl group having 1 to 10 carbon atoms, or a combination thereof, and examples thereof include the same alkyl, alkenyl, alkynyl, and aryl groups.

The carbonate bond may represent a structure represented by -O-C (O) -O-.

The carbamate bond may have a structure represented by -NH-C (O) -O-, -OC (O) -NH-, -NR-C (O) -O-, or -OC . R is an alkyl group, an alkenyl group, an alkynyl group, or an aryl group having 1 to 10 carbon atoms, or a combination thereof, and examples thereof include the same alkyl, alkenyl, alkynyl, and aryl groups.

R ₉ and R ₁₀ in the formula (4) each independently represent a structure selected from a single bond, an alkylene group having 1 to 10 carbon atoms, an alkenylene group, an alkynylene group or an arylene group, or a combination thereof. When any one of R ₉ and R ₁₀ is a single bond, R ₉ or R ₁₀ is a structure selected from the group which alkenyl alkylene group, Al having 2 to 10 carbon atoms group, an alkynylene group or an arylene group, or combinations thereof.

Examples of the alkylene group include a structure in which one hydrogen atom is removed from the alkyl group. Specific examples thereof include a methylene group, a 1,1-ethylene group, a 1,2-ethylene group, a 1,2-propylene group, a 1,3-propylene group, Propylene group, a 1,2-cyclopentylene group, a 1,2-cyclobutylene group, a 1,3-cyclohexylene group, a 1,2- Butylene group, 1,2-cyclopentylene group, 1,2-cyclohexylene group and the like.

Examples of the alkenylene group include a structure in which one hydrogen atom is removed from the alkenyl group. More specifically, examples thereof include a 1,1-ethenylene group, a 1,2-ethenylene group, a 1,2-ethenylene methylene group, a 1-methyl-1,2-ethenylene group, , 1-ethylene group, 1,2-ethenylene-1,2-ethylene group, 1,2-ethenylene-1,2-propylene group, 1,2-ethenylene 1,3- -Butylene group, an ethenylene-1,4-butylene group and a 1,2-ethenylene-1,2-butylene group.

Examples of the alkynylene group include a structure in which one hydrogen atom is removed from the alkynyl group. Specific examples thereof include an ethynylene group, an ethynylene-1,2-ethylene group, an ethynylene-1,2-propylene group, an ethynylene- -Propylene group, ethynylene-1,4-butylene group, ethynylene-1,2-butylene group and the like.

Examples of the arylene group include a structure in which one hydrogen atom is removed from the aryl group. More specifically, examples thereof include a 1,2-phenylene group, a 1,3-phenylene group and a 1,4-phenylene group.

When a diamine having a high linearity or a rigid structure is used, a liquid crystal alignment film having good liquid crystal alignability can be obtained. Therefore, the structure of A ₁ is a single bond or a structure represented by the following formulas (A1-1) to (A1-25 ) Is more preferable.

[Chemical formula 10]

(11)

[Chemical Formula 12]

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

The more rigid the structure of the diamine compound is, the more preferable is a liquid crystal alignment film having excellent liquid crystal alignability. Therefore, p-phenylenediamine represented by the formula (2) is particularly preferable as the diamine compound for obtaining the polyamic acid of the present invention .

The content of the diamine compound represented by the above formulas (2) and (3) is preferably 60 mol% to 100 mol% of the total diamine. The higher the proportion of the diamine represented by the above formulas (2) and (3), the better the liquid crystal alignment film having a good liquid crystal alignability, and more preferably 80 mol% to 100 mol%, further preferably 90 mol% to 100 mol% desirable.

The tetracarboxylic acid dianhydride for obtaining the polyamic acid as the component (A) of the present invention contains tetracarboxylic acid dianhydride represented by the following formula (6) in addition to the tetracarboxylic acid dianhydride represented by the formula (1) .

[Chemical Formula 16]

In the formula (6), X is a tetravalent organic group and its structure is not particularly limited. Specific examples include structures of the following formulas (X-5) to (X-46). From the viewpoint of the availability of the compound, the structure of X may be X-5, X-6, X-8, X-16, X-17, X-19, X- X-28, X-32, and X-46. X-16, X-19, X-25, and X-25 are preferably used as the structure of X. It is preferable to use a tetracarboxylic acid dianhydride having an aliphatic and aliphatic cyclic structure in order to improve the transparency of the resulting liquid crystal alignment film. Or X-46 is more preferable. It is also preferable to use tetracarboxylic acid dianhydride having an aromatic ring structure from the viewpoint of obtaining a liquid crystal alignment film that can alleviate the residual charge accumulated by the DC voltage. Examples of the structure of X include X-26, X -27, X-28, X-32, X-35 or X-37 are more preferable.

When the amount of the tetracarboxylic acid dianhydride represented by the formula (6) is excessively large, the liquid crystal alignment property of the liquid crystal alignment film obtained by the photo alignment method may be lowered. Therefore, the tetracarboxylic acid dianhydride represented by the formula (6) is preferably 0 to 40 mol%, more preferably 0 to 20 mol%, based on the total tetracarboxylic acid dianhydride.

[Chemical Formula 17]

[Chemical Formula 18]

[Chemical Formula 19]

[Chemical Formula 20]

The diamine compound for obtaining the polyamic acid of the component (A) of the present invention may contain a diamine compound represented by the following formula (7) in addition to the diamine compound represented by the formulas (2) and (3). In the formula, Y is a divalent organic group and its structure is not particularly limited. Specific examples of Y include structures of the following formulas (Y-1) to (Y-68).

[Chemical Formula 21]

[Chemical Formula 22]

(23)

≪ EMI ID =

(25)

(26)

(27)

(28)

Y-20, Y-21, Y (Y), and Y (Y) are preferable examples of the diamine compounds other than the formula (2) -22, Y-27, Y-28, Y-66, Y-67 or Y-68 are more preferable, and Y-66 is particularly preferable.

When the amount of the diamine compound represented by the formula (7) is too large, the liquid crystal alignment property of the liquid crystal alignment film is lowered, so that the amount is preferably 0 to 40 mol%, more preferably 0 to 20 mol% desirable.

≪ Component (B) >

The component (B) of the present invention is at least one imidazole derivative selected from the group consisting of the following formulas (B-1) to (B-4).

[Chemical Formula 29]

In the formulas, R ₅ to R ₈ are each independently an alkyl group having 3 to 10 carbon atoms or an alkenyl group having 3 to 10 carbon atoms.

Examples of the alkyl group having 3 to 10 carbon atoms include a propyl group, a butyl group, a t-butyl group, a hexyl group, an octyl group, a nonyl group and a decyl group. Examples of the alkenyl group include those obtained by substituting at least one CH-CH structure in the alkyl group with a C = C structure. More specifically, allyl group, 1-propenyl group, isopropenyl group, A 1-butadienyl group, a 2-pentenyl group, a 2-hexenyl group, and the like.

When the chain length of the alkyl group or the alkenyl group of the imidazole derivative is long, there is a possibility that the liquid crystal alignability is deteriorated and the liquid crystal alignability of the obtained liquid crystal alignment film is lowered. Therefore, the number of carbon atoms is more preferably from 3 to 6, and a propyl group, a butyl group, or an allyl group is particularly preferable.

Specific examples of the imidazole derivatives include 1-propylimidazole, 1-allylimidazole, 1-butylimidazole, 2-propylimidazole and 2-butylimidazole. 1-propylimidazole, 1-allylimidazole or 1-butylimidazole is more preferable, and 1-butylimidazole is particularly preferable.

If the content of the component (B) is too large, the liquid crystal alignment property of the resulting liquid crystal alignment film may be impaired. If the content is too small, the effect of the present invention may not be sufficiently obtained. Therefore, the content of the component (B) is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and particularly preferably 0.1 to 10 parts by mass, relative to 100 parts by mass of the component (A).

<Production method of polyamic acid>

The polyamic acid used as the liquid crystal aligning agent of the present invention can be obtained by the reaction of a tetracarboxylic acid dianhydride with a diamine.

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

The organic solvent used in the reaction is preferably N, N-dimethylformamide, N-methyl-2-pyrrolidone or? -Butyrolactone from the solubility of the monomer and the polymer, May be mixed and used. The concentration of the polymer is preferably from 1 to 30 mass%, more preferably from 5 to 20 mass%, from the viewpoint that the precipitation of the polymer is hardly caused and the high molecular weight material is easily obtained.

The polyamic acid thus obtained can be recovered by precipitation by injecting the reaction solution into a poor solvent while stirring well. In addition, precipitation is carried out several times, followed by washing with a poor solvent, followed by drying at room temperature or by heating, whereby a purified polyamic acid powder can be obtained. Examples of the poor solvent include, but are not limited to, water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

<Liquid Crystal Aligner>

The liquid crystal aligning agent of the present invention has a form of a solution in which components (A) and (B) are dissolved in an organic solvent. The molecular weight of the polyamic acid as the component (A) is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000 in terms of weight average molecular weight. 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 content of the polyamic acid as the component (A) in the liquid crystal aligning agent of the present invention can be appropriately changed according to the setting of the thickness of the coating film to be formed, but is preferably 1% by mass or more from the viewpoint of forming a uniform and defect- By mass, more preferably not less than 3% by mass, and not more than 10% by mass, and more preferably not more than 8% by mass, from the viewpoint of the preservation stability of the solution.

The organic solvent contained in the liquid crystal aligning agent of the present invention is not particularly limited as long as the components (A) and (B) are uniformly dissolved. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl- Pyrrolidone, N-vinyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone, gamma -butyrolactone, 1,3-dimethyl-imidazolidinone, 3- Methoxy-N, N-dimethylpropanamide, and the like. These may be used alone or in combination of two or more. Even if the solvent can not dissolve the polymer component uniformly, it may be mixed with the organic solvent as long as the solvent does not precipitate the polymer.

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

As the liquid crystal aligning agent of the present invention, other than the above, a polymer other than the polymer as the component (A) may be used as long as the effect of the present invention is not impaired, and a dielectric or a conductive material for changing electrical characteristics such as dielectric constant and conductivity of the liquid crystal alignment film A silane coupling agent for improving the adhesion between the liquid crystal alignment film and the substrate, a crosslinkable compound for increasing the hardness and denseness of the film when the film is used as a liquid crystal alignment film, and moreover, the imidization of the polyamic acid An imidization accelerator for the purpose of promoting the reaction to the reaction product.

&Lt; Liquid crystal alignment film &

The liquid crystal alignment film of the present invention is a coating film obtained by applying the liquid crystal aligning agent thus obtained to a substrate, followed by drying and firing, and is obtained by irradiating the coated film surface with substantially linearly polarized radiation.

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

The drying and firing steps after the application of the liquid crystal aligning agent of the present invention can be carried out at arbitrary temperature and time. The organic solvent contained therein is sufficiently removed and the polyamic acid as the component (A) is dried at 50 to 120 ° C for 1 to 10 minutes to imidize the polyamic acid, and then dried at 150 to 300 ° C for 5 to 120 minutes Fired. The thickness of the coated film after firing is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may deteriorate. Therefore, it is 5 to 300 nm, preferably 10 to 200 nm.

The liquid crystal aligning agent of the present invention is particularly useful when used in photo-alignment treatment.

Specific examples of the photo-alignment treatment method include a method of irradiating the surface of the above coating film with polarized radiation in a certain direction and, if necessary, further heating treatment at a temperature of 150 to 250 ° C to give a liquid crystal aligning ability . As the wavelength of the radiation, ultraviolet rays or visible rays having a wavelength of 100 nm to 800 nm can be used. Of these, ultraviolet rays having a wavelength of 100 nm to 400 nm are preferable, and those having a wavelength of 200 nm to 400 nm are particularly preferable. In addition, in order to improve the liquid crystal alignment property, the coated film substrate may be irradiated with radiation while heating at 50 to 250 ° C. The irradiation dose of the radiation is preferably in the range of 1 to 10,000 mJ / cm 2, and particularly preferably in the range of 100 to 5,000 mJ / cm 2.

The liquid crystal alignment film produced as described above can stably orient liquid crystal molecules in a predetermined direction.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Hereinafter, the abbreviations of the compounds used in this embodiment and the comparative examples and the measurement methods of the respective properties are as follows.

DA-1: (formula (DA-1))

(30)

NMP: N-methyl-2-pyrrolidone

BCS: butyl cellosolve

[Viscosity]

In the synthesis examples, the viscosity of the polyamic acid ester and the polyamic acid solution was measured using a E-type viscometer TVE-22H (manufactured by Toki Industries) at a sample amount of 1.1 ml, a cone TE-1 (1 ° 34 ' &Lt; / RTI &gt;

[Molecular Weight]

The molecular weight of the polyamic acid ester is measured by a GPC (room temperature gel permeation chromatography) apparatus, and the number average molecular weight (hereinafter also referred to as Mn) and the weight average molecular weight (hereinafter also referred to as Mw) of polyethylene glycol and polyethylene oxide ).

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

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

Column temperature: 50 ° C

Eluent: 30 mmol / l of lithium bromide monohydrate (LiBr.H ₂ O), 30 mmol / l of phosphoric acid / anhydrous crystal (o-phosphoric acid) as an additive, N, N-dimethylformamide (THF) of 10 ml / l)

Flow rate: 1.0 ml / min

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

[AC drive burn-in of FFS driven liquid crystal cell]

An ITO electrode having a thickness of 50 nm was used as an electrode in the first layer, silicon nitride having a thickness of 500 nm was used as an insulating film in the second layer, and a comb-like ITO electrode (electrode width: 3 A liquid crystal aligning agent was applied by spin coating to a glass substrate on which electrodes for driving Fringe Field Switching (hereinafter referred to as FFS) having a thickness of 5 μm, an electrode pitch of 6 μm and an electrode height of 50 nm were formed Respectively. Dried on a hot plate at 80 DEG C for 5 minutes and then baked in a hot air circulating oven at 250 DEG C for 60 minutes to form a 100 nm thick coating film. An ultraviolet ray having a wavelength of 254 nm was irradiated to the coated film surface via a polarizing plate to obtain a substrate having a liquid crystal alignment film formed thereon. A coating film was similarly formed on a glass substrate having a columnar spacer having a height of 4 占 퐉, which had no electrode as an opposing substrate, and subjected to alignment treatment.

The two substrates were set as one set, a sealing agent was printed on the substrate, and another substrate was stuck so that the alignment direction of the liquid crystal alignment film face was 0 °, and then the sealing agent was cured, Respectively. Liquid crystal MLC-2041 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell.

The VT characteristic (voltage-transmittance characteristic) of this FFS-driven liquid crystal cell under a temperature of 58 ° C was measured, and then a square wave of ± 4 V / 120 Hz was applied for 4 hours. After 4 hours, it cuts off the voltage, and then allowed to stand 60 minutes under the temperature of 58 ℃, again yielding a difference between the voltage that is measured by a 50% transmittance of the applied square wave before and after the VT characteristic (ΔV _50).

(Synthesis Example 1)

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

(Synthesis Example 2)

11.68 g (0.108 mol) of p-phenylenediamine and 2.41 g (0.0120 mol) of 4,4-diaminodiphenyl ether were placed in a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, Was added and dissolved with stirring while nitrogen was being supplied. While stirring the diamine solution, 22.82 g (0.116 mol) of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride was added, NMP was further added so that the solid content concentration became 8 mass%, and 24 Followed by stirring for a period of time to obtain a solution of polyamic acid (PAA-2). The viscosity of the polyamic acid solution at 25 캜 was 178 mPa.. The molecular weight of this polyamic acid was Mn = 14209 and Mw = 37227.

(Synthesis Example 3)

11.67 g (0.108 mol) of p-phenylenediamine and 2.40 g (0.0119 mol) of 4,4-diaminodiphenyl ether were placed in a 500 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, Was added and dissolved with stirring while nitrogen was being supplied. While this diamine solution was stirred, 21.17 g (0.108 mol) of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride was added, 38 g of NMP was added, and the mixture was stirred at room temperature for 2 hours. Next, 1.83 g (8.39 mmol) of pyromellitic dianhydride was added, NMP was further added so that the solid concentration became 8% by mass, and the mixture was stirred at room temperature for 24 hours to obtain a solution of polyamic acid (PAA-3) . The viscosity of this polyamic acid solution at 25 캜 was 168 mPa.. The molecular weight of the polyamic acid was Mn = 15454 and Mw = 41309.

(Synthesis Example 4)

19.46 g (0.180 mmol) of p-phenylenediamine and 4.47 g (0.0188 mol) of DA-1 were taken in a 1000 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, and 502 g of NMP was added , And dissolved with stirring while nitrogen was being supplied. While this diamine solution was stirred, 38.05 g (0.194 mol) of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride was added, NMP was further added so that the solid content concentration became 10 mass%, and 24 And stirred for a time to obtain a solution of polyamic acid (PAA-4). The viscosity of this polyamic acid solution at 25 캜 was 462 mPa s. The molecular weight of this polyamic acid was Mn = 16976 and Mw = 43749.

(Synthesis Example 5)

45.96 g (0.425 mmol) of p-phenylenediamine and 17.80 g (0.075 mol) of DA-1 were taken in a 1000 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 1390 g of NMP was added , And dissolved with stirring while nitrogen was being supplied. While stirring the diamine solution, 107.83 g (0.481 mol) of 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic acid dianhydride was added, and NMP was further added thereto so as to have a solid content concentration of 10 mass% And the mixture was stirred at room temperature for 24 hours to obtain a solution of polyamic acid (PAA-5). The viscosity of this polyamic acid solution at 25 캜 was 215 mPa.. The molecular weight of the polyamic acid was Mn = 12629 and Mw = 29521.

(Example 1)

5.01 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was taken in a 20 ml sample tube equipped with a stirrer, 3.00 g of NMP, 2.01 g of BCS and 0.04 g of 1-butylimidazole were added, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-1).

(Example 2)

5.02 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was put into a 20 ml sample tube equipped with a stirrer, 3.01 g of NMP, 2.04 g of BCS and 0.04 g of 1-allylimidazole were added, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-2).

(Example 3)

4.02 g of the polyamic acid solution (PAA-4) obtained in Synthetic Example 4 was taken in a 20 ml sample tube equipped with a stirrer, NMP (4.00 g), BCS (2.01 g) and 1-butyl imidazole (0.04 g) And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-3).

(Example 4)

5.02 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1, 3.01 g of NMP, 2.00 g of BCS and 0.04 g of 2-butylimidazole were added to a 20-ml sample tube equipped with a stirrer, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-4).

(Comparative Example 1)

5.01 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1, 3.00 g of NMP, 2.01 g of BCS and 0.04 g of 1-ethylimidazole were added to a 20 ml sample tube containing the stirrer, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (B-1).

(Comparative Example 2)

5.00 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was put into a 20 ml sample tube containing an agitator, 3.03 g of NMP, 2.02 g of BCS and 0.04 g of 1-benzoylimidazole were added, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (B-2).

(Comparative Example 3)

5.01 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was placed in a 20 ml sample tube equipped with a stirrer, 3.05 g of NMP, 2.00 g of BCS, and 1- (2-hydroxyethyl) imidazole , And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (B-3).

(Comparative Example 4)

5.02 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1, 3.00 g of NMP and 2.00 g of BCS were added to a 20 ml sample tube into which a stirrer was placed, and the mixture was stirred with a magnetic stirrer for 30 minutes, (B-4) was obtained.

(Example 5)

The liquid crystal aligning agent (A-1) obtained in Example 1 was filtered with a filter having a size of 1.0 mu m and then an ITO electrode having a thickness of 50 nm as a first layer and an ITO electrode having a thickness of 500 Nm silicon nitride as the first layer and a comb-like ITO electrode (electrode width: 3 mu m, electrode gap: 6 mu m, electrode height: 50 nm) as the third layer was spin coated Lt; / RTI &gt; Dried on a hot plate at 80 DEG C for 5 minutes and then fired in a hot air circulating oven at 230 DEG C for 30 minutes to form a coating film having a film thickness of 100 nm. An ultraviolet ray having a wavelength of 254 nm was irradiated with 1,500 mJ / cm2 through this polarizing plate on the coated film surface to obtain a substrate having a liquid crystal alignment film formed thereon. A coating film was similarly formed on a glass substrate having a columnar spacer having a height of 4 占 퐉 and on which no electrode was formed as a counter substrate, and alignment treatment was carried out.

A sealant was printed on the substrate with one set of the two substrates, and another substrate was stuck so that the alignment direction of the liquid crystal alignment film face was 0 °, and then the sealant was cured to prepare a blank cell Respectively. Liquid crystal MLC-2041 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell.

The AC drive burn-in characteristics of this FFS-driven liquid crystal cell were evaluated. As a result,? V ₅₀ was 2 mV.

(Example 6)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (A-2) obtained in Example 2 was used. The AC drive burn-in characteristics of this FFS-driven liquid crystal cell were evaluated. As a result,? V ₅₀ was 2 mV.

(Example 7)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (A-3) obtained in Example 3 was used. As a result of evaluating the AC drive burn-in characteristics for this FFS-driven liquid crystal cell,? V ₅₀ was 0 mV.

(Example 8)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (A-4) obtained in Example 4 was used. The AC drive burn-in characteristics of this FFS-driven liquid crystal cell were evaluated. As a result,? V ₅₀ was 2 mV.

(Comparative Example 5)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (B-1) obtained in Comparative Example 1 was used. As a result of evaluating the AC drive burn-in characteristics of this FFS-driven liquid crystal cell,? V ₅₀ was 4 mV.

(Comparative Example 6)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (B-2) obtained in Comparative Example 2 was used. As a result of evaluating the AC drive burn-in characteristics of this FFS-driven liquid crystal cell,? V ₅₀ was 4 mV.

(Comparative Example 7)

An FFS-driven liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (B-3) obtained in Comparative Example 3 was used. As a result of evaluating the AC drive burn-in characteristics of this FFS-driven liquid crystal cell,? V ₅₀ was 4 mV.

(Comparative Example 8)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (B-4) obtained in Comparative Example 4 was used. As a result of evaluating the AC drive burn-in characteristics for this FFS-driven liquid crystal cell,? V ₅₀ was 5 mV.

(Example 9)

5.00 g of the polyamic acid solution (PAA-2) obtained in Synthetic Example 2 was taken in a 20 ml sample tube equipped with a stirrer, 3.02 g of NMP, 2.04 g of BCS and 0.04 g of 1-butylimidazole were added, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-5).

(Example 10)

5.02 g of the polyamic acid solution (PAA-3) obtained in Synthesis Example 3, 3.00 g of NMP, 2.03 g of BCS and 0.04 g of 1-butylimidazole were added to a 20 ml sample tube equipped with a stirrer, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-6).

(Example 11)

4.00 g of the polyamic acid solution (PAA-5) obtained in Synthesis Example 5, 2.01 g of NMP, 2.00 g of BCS and 0.04 g of 1-butylimidazole were added to a 20 ml sample tube equipped with a stirrer, And the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal aligning agent (A-7).

(Example 12)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (A-5) obtained in Example 9 was used. The AC drive burn-in characteristics of this FFS-driven liquid crystal cell were evaluated. As a result,? V ₅₀ was 2 mV.

(Example 13)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (A-6) obtained in Example 10 was used. The AC drive burn-in characteristics of this FFS-driven liquid crystal cell were evaluated. As a result,? V ₅₀ was 2 mV.

(Example 14)

An FFS-driving liquid crystal cell was fabricated in the same manner as in Example 5 except that the liquid crystal aligning agent (A-7) obtained in Example 11 was used to irradiate 500 mJ / cm 2 of ultraviolet ray having a wavelength of 254 nm. As a result of evaluating the AC drive burn-in characteristics for this FFS-driven liquid crystal cell,? V ₅₀ was 1 mV.

Industrial availability

The liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention is particularly useful as a liquid crystal alignment film of an IPS driving system or an FFS driving system or a liquid crystal alignment film of a liquid crystal television.

The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2011-137770 filed on June 21, 2011 are hereby incorporated herein by reference as the disclosure of the specification of the present invention.

Claims (10)

A liquid crystal aligning agent characterized by comprising the following components (A), (B) and an organic solvent.
(A): a tetracarboxylic acid dianhydride containing a tetracarboxylic acid dianhydride represented by the following formula (1) in an amount of 60 mol% or more of the total tetracarboxylic acid dianhydride and a diamine compound represented by the following formula (2) And a diamine compound represented by the following formula (3) in an amount of at least 60 mol% of the total diamine compound.
[Chemical Formula 1]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ 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 alkenyl group having 2 to 6 carbon atoms An alkynyl group or a phenyl group)
(2)

(In the formula (3), A 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)
Component (B): at least one imidazole derivative selected from the group consisting of the following formulas (B-1) to (B-4).
(3)

(Formula (B-1) ~ (according to _{B-4), R 5,} R 6, R 7 and R ₈ is an alkyl group, or an alkenyl group having 3 to 10 carbon atoms, each independently) The method according to claim 1,
Wherein the content of the component (A) is 1 to 10% by mass. The method according to claim 1,
Wherein the content of the component (B) is 0.1 to 50 parts by mass relative to 100 parts by mass of the component (A). The method according to claim 1,
Wherein the tetracarboxylic acid dianhydride for obtaining the component (A) is at least one selected from the group consisting of 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride and 1,3-dimethyl-1,2,3,4-cyclobutanetetracar And at least one tetracarboxylic acid dianhydride selected from the group consisting of tetracarboxylic dianhydride and tetracarboxylic dianhydride. The method according to claim 1,
A liquid crystal aligning agent wherein the diamine compound for obtaining the component (A) is a diamine compound containing at least 60 mol% of the diamine compound represented by the formula (2) in the total diamine compound. The method according to claim 1,
Wherein the imidazole derivative of the component (B) is at least one selected from the group consisting of 1-propylimidazole, 1-allylimidazole, 1-butylimidazole, 2-propylimidazole, One kind of liquid crystal aligning agent. The method according to claim 1,
Wherein the imidazole derivative of the component (B) is at least one member selected from the group consisting of 1-allylimidazole, 1-propylimidazole, and 1-butylimidazole. The method according to claim 1,
Wherein the diamine compound for obtaining the component (A) further contains a diamine compound represented by the following formula (DA-1).
[Chemical Formula 4]

A liquid crystal alignment film obtained by applying and firing the liquid crystal aligning agent according to any one of claims 1 to 8. A liquid crystal alignment film obtained by coating and firing the liquid crystal aligning agent according to any one of claims 1 to 8, and subsequently irradiating with polarized radiation.