TWI421600B - Liquid crystal aligning agent and liquid crystal display element - Google Patents

Description

Liquid crystal alignment agent and liquid crystal display element

The present invention relates to a novel liquid crystal alignment agent and a liquid crystal alignment film formed from the liquid crystal alignment agent and a liquid crystal display element having the liquid crystal alignment film. More specifically, the present invention relates to exhibiting excellent coatability, high voltage holding ratio, and suppressing the voltage holding ratio by applying a light or heat pressure for a long time on a liquid crystal panel or driving the liquid crystal panel for a long time. Or a liquid crystal alignment agent produced by a scorch and a liquid crystal alignment film formed of the alignment agent, and a liquid crystal display element containing the liquid crystal alignment film.

From the viewpoints of space saving and low power consumption, liquid crystal display elements, which are representative of liquid crystal displays, have been developed into clocks, portable video games, word processors, notebook computers, and automobiles since the mass production of liquid crystal computers. Satellite navigation, cameras, PDAs, digital cameras, mobile phones, various monitors, LCD TVs, and many other applications continue to be popular. As a liquid crystal display element, a nematic liquid crystal having a positive dielectric anisotropy is used, and a TN (Twisted Nematic) liquid crystal having a long axis of liquid crystal molecules bent from one substrate to the other substrate at a continuous 90 degree is used. A display element or a TN type liquid crystal display element is widely used as a high contrast STN (Super Twisted Nematic) type liquid crystal display element. In addition, in recent years, the display quality of liquid crystal displays has to be further improved, and VA (Vertical Alignment) type liquid crystal display elements and IPS (In Plane) having small viewing angle dependence are required. An optically compensated bending (OCB) type liquid crystal display element having a small viewing angle dependence and a high-speed response of an image on the screen is also developed.

Among the liquid crystal display elements, the member for controlling the liquid crystal alignment is a liquid crystal alignment film. The liquid crystal alignment film is a liquid crystal alignment agent containing an imidized polymer obtained by imidating polyamic acid or the poly-proline, by roll coating, spin coating, flexographic printing A method, an inkjet method, or the like is applied to the substrate, and the coated surface is formed by heating and drying. Among them, the uneven coating of the alignment film is directly related to the poor alignment of the liquid crystal, which is a factor that significantly reduces the display quality of the liquid crystal panel. In the alignment agent containing polyimine which has been used in the past, the improvement of the electrical properties such as the retention ratio has been made to improve the imidization ratio of the polyimine, but the high imidization ratio and the coating property of the alignment agent. For the trade-off relationship, it is expected to develop a liquid crystal alignment agent having both excellent electrical properties and coating properties. Further, deterioration of the liquid crystal alignment film or impurity adsorption to the alignment film is presumed to cause deterioration in display performance such as reduction in voltage holding ratio, unevenness in planar display, flickering of the screen, and reduction in contrast. Heretofore, there has been an example of adding a polyfunctional epoxy compound to polyphosphoric acid as a method for improving the voltage holding ratio (JP-A-10-168455), and attempting to use poly-proline and an imidized polymer. Examples of the tetracarboxylic dianhydride of the raw material or the modification of the diamine skeleton (Patent No. 3572690 and JP-A-2001-228481), and an example in which an acrylic polymer is added to poly-proline (Patent No. 3206169) No. bulletin). However, in these reports, the initial voltage holding ratio, the addition of light or heat pressure on the liquid crystal panel, or the long-time driving of the liquid crystal panel, the reliability of the voltage retention rate is not improved. The effect was not examined at the same time from the viewpoint of improving the applicability at the time of formation of the alignment film. In recent years, as liquid crystal panels are suitable for liquid crystal TVs or high-quality monitors, liquid crystal alignment films cannot achieve high-quality display performance. In addition to high voltage retention, the reliability of voltage retention and coating properties during formation of alignment films must be Further improvement.

The present invention is based on the above circumstances, and therefore it is an object of the present invention to provide a coating which imparts good coating properties and which does not cause voltage retention even if the liquid crystal panel is driven for a long period of time under external light or heat pressure of the liquid crystal panel. A liquid crystal alignment agent for a liquid crystal alignment film which reduces or generates scorch marks, a liquid crystal alignment film, and a liquid crystal display element which can display a beautiful picture over a long period of time by the liquid crystal alignment film.

Other objects and advantages of the invention will be apparent from the description which follows.

The above object and advantage of the present invention are attained by a liquid crystal alignment agent containing a polymer having a repeating unit represented by the following formula (1).

(wherein R ₁ is a hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; or a monovalent polar group; A ₁ is a single bond or an alkylene group having 1 to 10 carbon atoms, and A ₂ , A ₃ and A _{4 are} each independently a single bond, an ether bond (-O-), a carbonyl group (-CO-), or a carbonyloxy group ( -COO-), oxycarbonyl (-OCO-), guanamine bond (-NHCO-, -CONH-), thioether bond (-S-) or alkylene group having a carbon number of 1 to 10, B ₁ , B ₂ And B _{3 are} each independently a single bond, 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,2-cyclohexyl, 1,3-cyclohexyl, 1 , 4-cyclohexyl or piperidine-1,4-diyl, R ₂ is a hydrogen atom, a hydrocarbon group having 1 to 50 carbon atoms or a group containing a fluorine atom, but adjacent to A ₁ to A ₄ and B ₁ to B _{When 3} is a single bond, it means a single bond, and when A ₁ ~A ₄ and B ₁ ~B _{3 both} represent a single bond, R _{2 is} not a hydrogen atom.)

Moreover, the above object of the present invention is to provide a liquid crystal alignment from the above The liquid crystal alignment film formed by the agent and the liquid crystal display element of the liquid crystal alignment film are obtained.

The best form of implementing the invention "Acrylic polymer with pre-tilt display component"

Hereinafter, the present invention will be described in detail. The liquid crystal alignment agent of the present invention is a polymer containing a repeating unit represented by the above formula (1) (hereinafter also referred to as "acrylic polymer having a pretilt display component"). The liquid crystal alignment agent of the present invention has an electrical property such as a pretilt angle expression and a voltage holding ratio which can control the liquid crystal alignment film by selecting the structure of the repeating unit represented by the above formula (1).

R ₁ in the above formula (1) is a hydrogen atom; a halogen atom; a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; Or a monovalent polar group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

Examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms include an alkyl group such as a methyl group, an ethyl group, and a propyl group; a cycloalkyl group such as a cyclopentyl group or a cyclohexyl group; and an alkenyl group such as a vinyl group or an allyl group; An alkylene group such as an ethylene group or a propylene group; an aromatic group such as a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group or a fluorenyl group. The hydrogen atom to which the carbon atom in the group is bonded may be substituted by, for example, a halogen atom such as fluorine, chlorine or bromine, a cyano group or the like.

Further, the above substituted or unsubstituted monovalent hydrocarbon group may be bonded directly to the polymer main chain skeleton or bonded via a linking group. Examples of the linking group include a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a ruthenium atom (for example, a carbonyl group (-CO-), a carbonyloxy group (-COO-), or an oxycarbonyl group (-OCO-). , sulfonyl (-SO ₂ -), sulfonyloxy (-SO ₂ -O-), oxysulfonyl (-O-SO ₂ -), ether linkage (-O-), thioether linkage (- S-), an imido group (-NH-), a guanamine bond (-NHCO-), a decane bond (-Si(R) ₂ O-) (wherein R is an alkyl group such as a methyl group or an ethyl group) And a combination of two or more of them, and when the substituted or unsubstituted monovalent hydrocarbon group is a cycloalkyl group or an aromatic group, the linking group may be a divalent hydrocarbon group having 1 to 10 carbon atoms ( For example, it may be -(CH ₂ )m- (wherein, m is an alkyl group represented by an integer of 1 to 10).

Examples of the monovalent polar group include a hydroxyl group, a cyano group, a nitro group, a decylamino group, an imido group (=NH), a triorganocarbyloxy group, a triorganosylalkyl group, an amine group, a decyl group, and an alkane group. An oxymethane alkyl group, a sulfonic acid group (-SO ₃ H), a sulfinyl group (-SO ₂ H), a carboxyl group, and the like.

Further, examples of the specific organomethane alkoxy group include a trimethylmethane alkoxy group and a triethylmethane alkoxy group; and examples of the triorganomylalkyl group include a trimethylmethane group. Examples of the amine group include a second-order amine group and a third-order amine group. Examples of the alkoxymethyl sulfonyl group include trimethoxymethyl sulfonyl group and triethyl ethene. Oxymethane alkyl and the like.

Further, R ₂ is a group containing a hydrogen atom, a hydrocarbon group having 1 to 50 carbon atoms, or a fluorine atom. Examples of the group having a hydrocarbon group having 1 to 50 carbon atoms or a fluorine atom include a linear alkyl group such as a methyl group, an ethyl group, a propyl group, an n-dodecyl group or an n-octadecyl group, and 2-ethyl group. a branched alkyl group such as a hexyl group; a cycloalkyl group such as a cyclopentyl group or a cyclohexyl group; a group having an aliphatic condensed polycyclic structure such as a steroid skeleton; an alkenyl group such as a vinyl group or an allyl group; an ethylene group and a propylene group; An alkylene group; an aromatic group such as a phenyl group, a naphthyl group, an anthranyl group, a biphenyl group or a fluorenyl group; and a hydrogen atom bonded to a carbon atom in the group may be a halogen atom such as fluorine, chlorine or bromine or a trifluoro atom. a substituted group such as a methyl group or a trifluoromethoxy group. The choice of these bases can be selected by the pretilt performance necessary for the liquid crystal alignment film. For example, when used as a vertical alignment agent, R _{2 is} preferably a higher volume substituent, and is, for example, a linear or branched alkyl group having 6 or more carbon atoms, a complex cycloalkyl group, and an aromatic group. A base having an aliphatic condensed polycyclic structure such as a steroid skeleton or the like is preferred, and a group having a steroid skeleton is particularly preferable from the viewpoint of being able to stabilize a high pretilt angle.

In the formula (1), A ₁ is a single bond or an alkylene group having 1 to 10 carbon atoms, and each of A ₂ , A ₃ and A _{4 is} independently selected from a single bond, an ether bond (-O-), or a carboxyl group (-CO). -), carbonyloxy (-COO-), oxycarbonyl (-OCO-), guanamine bond (-NHCO-, -CONH-), thioether bond (-S-) and alkylene with 1 to 10 carbon atoms Based on the group of groups, B ₁ , B ₂ and B _{3 are} each independently a single bond, 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,2-ring Hexyl, 1,3-cyclohexyl, 1,4-cyclohexyl, piperidine-1,4-diyl.

The preferred structure shown in formula (1) is the following formula (3) (wherein, the definition of R _{6 is} the same as the definition of R _{1 of the} formula (1).)

Specific examples of the structure shown in the formula (1) include the following specific examples.

In the configuration exemplified as the specific example of the above formula (1), the advantages of the balance between the performance of the high pretilt angle and the electrical characteristics such as the voltage holding ratio are expressed by the formulas (1-3) and (1-4). The structure shown is particularly good.

Moreover, it is preferable that the acrylic polymer having a pretilt angle display component of the present invention further contains a structure having a cyclic ether structure represented by the following formula (2). In the cyclic ether structure in the structure represented by the formula (2), after the alignment film is formed, heat treatment is carried out by heat treatment (post-grilling) to improve heat resistance and liquid crystal resistance (solvent resistance) of the alignment film. At the film density, the effect of reducing the diffusion of impurity ions can be imparted. Further, by the effect of the above, even if light or heat pressure is applied to the liquid crystal panel or the liquid crystal panel is driven for a long time, a liquid crystal alignment film which does not lower the voltage holding ratio or generates a scorch mark can be obtained.

(wherein R ₃ is a hydrogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a halogen atom; a linking group of an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; or a monovalent polar group; R ₄ is a single bond or a divalent organic group, and R ₅ is a group having a cyclic ether structure having 2 to 10 carbon atoms.)

In the above formula (2), specific examples of R ₃ include the same groups as those of R ₁ in the above formula (1).

R ₄ is a single bond or a divalent organic group, preferably a divalent hydrocarbon group having 1 to 10 carbon atoms, for example, -(CH ₂ )n- (wherein n is an integer of 1 to 10).

The cyclic ether structure represented by R ₅ is a group having a thermal crosslinking reactivity of 2 to 10 carbon atoms, and is preferably an epoxy group or an oxetane group. Among them, epoxy groups are particularly preferred from the viewpoint of reactivity.

Specific examples of the repeating unit represented by the above formula (2) are structural units represented by the following formula (4), and examples thereof include epoxypropyl acrylate, epoxy methacrylate, and acrylic-3,4. - Epoxy butyl, 3,4-epoxy butyl methacrylate, -6,7-epoxypentyl acrylate, -6,7-epoxypentyl methacrylate, α-B A structural unit in which a radically polymerizable unsaturated compound containing a cyclic ether group such as a 6,7-epoxypentyl group having a radical polymerization is polymerized.

(wherein R _{7 is} each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group of an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; or 1 The price is a polar base, and a is an integer from 1 to 10.)

In the formula (4), specific examples of R ₇ include the same groups as R _{1 of the} above formula (1).

Among them, the thermal density of the alignment film of the alignment film is high, and the structural unit of the epoxy propyl methacrylate or the methacrylic acid methacrylate is used from the viewpoint of excellent electrical properties and reliability of electrical properties. Very good.

Further, in order to promote the crosslinking reaction of the cyclic ether structure represented by the above formula (2), the acrylic polymer having a pretilt angle display component of the present invention preferably contains a repeating unit having a carboxylic acid group, and as a specific example, It is preferred that the radically polymerizable carboxylic acid group-containing compound has a structural unit to be polymerized. Examples of the structural unit having a carboxylic acid group include a repeating unit in which a monocarboxylic acid precursor represented by the following formula (5) is polymerized or maleic acid, fumaric acid, citraconic acid, mesaconic acid, and clothing. A repeating unit in which a dicarboxylic acid precursor such as a benic acid is polymerized.

(wherein R _{8 is} each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group of an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; or 1 valence Polar base.)

In the formula (5), specific examples of R ₈ include the same groups as R _{1 of the} above formula (1).

Among them, from the viewpoint of high film density of the thermosetting hardened alignment film and showing the reliability of electrical characteristics and electrical characteristics, polymerized acrylic acid is used. The structural unit of methacrylic acid and crotonic acid is particularly good.

The acrylic polymer of the present invention having a pretilt display component is intended to impart heat resistance. It is preferable to have a structure shown by each of the following formulas (6) and (7).

(In the above formula, R ₉ represents a substituted or unsubstituted hydrocarbon group having 1 to 50 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom, and R ₁₀ and R _{11 are} each independently a hydrogen atom. a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; or a monovalent polar group.

In the formula (6), R ₉ is a substituted or unsubstituted hydrocarbon group having 1 to 50 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom, and a specific example thereof is a phenyl group or a naphthalene group. The aromatic group such as a group, a fluorenyl group or a fluorenyl group is preferably a cycloalkyl group such as a cyclopentyl group or a cyclohexyl group, and particularly preferably a phenyl group or a cyclohexyl group.

In the formula (7), R ₁₀ and R ₁₁ each independently represent a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom: 1 to 30 The hydrocarbon group or the monovalent polar group may, for example, be the same as R ₁ in the above formula (1). Specific examples of the structure represented by the formula (7) include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-anthracene. A structural unit of a vinyl aromatic compound such as an olefin such as an olefin and a styrene, a 4-vinylbiphenyl, a 2-vinylbiphenyl, a 1-vinylnaphthalene, a 2-vinylnaphthalene or an α-methylstyrene is preferably polymerized. Among them, the structural units in which styrene is polymerized are particularly preferred.

Examples of the solvent used in the production of the acrylic polymer having a pretilt display component of the present invention include alcohols, ethers, glycol ethers, ethylene glycol alkyl ether acetates, and diethylene glycol alkyl ethers. , propylene glycol monoalkyl ether, propylene glycol alkyl ether acetate, propylene glycol alkyl ether propionate, aromatic hydrocarbon, ketone, ester, and the like.

Specific examples of the alcohol include methanol, ethanol, benzyl alcohol, 2-phenylethanol, and 3-phenyl-1-propanol. Examples of the ether include tetrahydrofuran and di-n-. Amyl ether and the like; examples of the glycol ether include ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; and examples of the ethylene glycol alkyl ether acetate include methyl ethyl Glycol diethyl ether acetate, ethyl glycol ethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoethyl ether acetate, etc.; as diethylene glycol alkyl ether, for example Examples thereof include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, and the like; Examples of the propylene glycol monoalkyl ether include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether; and examples of the propylene glycol alkyl ether propionate include propylene glycol. Methyl ether propionate, propylene glycol Ethyl ether propionate, propylene glycol propyl ether propionate, propylene glycol butyl ether propionate, etc.; as the propylene glycol alkyl ether acetate, for example, propylene glycol methyl ether acetate, propylene glycol ethyl ether B An acid ester, propylene glycol propyl ether acetate, propylene glycol butyl ether acetate, etc., and examples of the aromatic hydrocarbon include toluene, xylene, and the like;

Examples of the ketone include methyl ethyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone; and examples of the ester include methyl acetate and ethyl acetate. , propyl acetate, butyl acetate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, methyl hydroxyacetate, glycolic acid Ethyl ester, butyl glycolate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 3-hydroxypropionate, ethyl 3-hydroxypropionate, propyl 3-hydroxypropionate, 3- Butyl hydroxypropionate, methyl 2-hydroxy-3-methylbutanoate, methyl methoxyacetate, ethyl methoxyacetate, propyl methoxyacetate, butyl methoxyacetate, ethoxylate Methyl acetate, ethyl ethoxyacetate, propyl ethoxyacetate, butyl ethoxyacetate, methyl propoxyacetate, ethyl propoxyacetate, propyl propoxyacetate, propoxyacetic acid Butyl ester, methyl butoxyacetate, ethyl butoxide, propyl butoxyacetate, butyl butoxyacetate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate , Propyl 2-methoxypropionate, butyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, propyl 2-ethoxypropionate, Butyl 2-ethoxypropionate, methyl 2-butoxypropionate, ethyl 2-butoxypropionate, propyl 2-butoxypropionate, butyl 2-butoxypropionate, Methyl 3-methoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, Methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, propyl 3-ethoxypropionate, butyl 3-ethoxypropionate, methyl 3-propoxypropionate, Ethyl 3-propoxypropionate, propyl 3-propoxypropionate, butyl 3-propoxypropionate, methyl 3-butoxypropionate, ethyl 3-butoxypropionate, An ester of propyl 3-butoxypropionate or butyl 3-butoxypropionate.

Among them, ethylene glycol alkyl ether acetate, diethylene glycol alkyl ether, propylene glycol monoalkyl ether, propylene glycol alkyl ether acetate is preferred, diethylene glycol dimethyl ether, two Ethylene glycol ethyl methyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol methyl ether acetate, and 3-methoxypropionic acid methyl group are particularly preferred.

As the polymerization initiator used in the production of the acrylic polymer having a pretilt display component of the present invention, those generally known as radical polymerization initiators can be used. For example, 2,2'-azobisisobutyrine, 2,2'-azobis-(2,4-dimethylpentaphthalene), 2,2'-azobis-(4-A Azo compound such as oxy-2,4-dimethylpentan); benzamidine peroxide, laurel peroxide, t-butylperoxytrimethylacetate, 1,1'-bis-( An organic peroxide such as t-butyl peroxide) cyclohexane; and hydrogen peroxide. As a radical polymerization initiator When a peroxide is used, the peroxide is used together with the reducing agent, and can also be used as a redox type initiator.

In the production of the acrylic polymer having a pretilt angle display component of the present invention, a molecular weight modifier can be used in order to adjust the molecular weight. Examples of such a specific example include halogenated hydrocarbons such as chloroform and carbon tetrabromide; n-hexyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, tert-lauryl mercaptan, and thioglycolic acid. Equivalent mercaptan; dimethyl sulfide sulfonate, diisopropyl disulfide sulfonate Isosulfonate; terpinolene, α-methylstyrene dimer, and the like.

The acrylic polymer having a pretilt display component of the present invention can be polymerized by its polymerization conditions, for example, solvent type, solvent/monomer loading ratio (weight ratio), polymerization temperature, initiator type and addition amount thereof, chain movement The type of the agent and the amount of addition thereof are appropriately adjusted to control the desired molecular weight. The polystyrene-equivalent weight average molecular weight (hereinafter referred to as "Mw") measured by gel permeation chromatography (GPC) using the acrylic polymer having a pretilt angle display component of the present invention is preferably 2 × 10 ³ ~ 1 × 10 ⁶ , more preferably 5 × 10 ³ ~ 5 × 10 ⁵ , particularly preferably 1 × 10 ⁴ ~ 4 × 10 ⁵ . When the Mw is less than 2 × 10 ³ , an appropriate viscosity cannot be obtained as an alignment agent, so that an alignment film having a desired film thickness cannot be formed, and the heat resistance of the alignment film is poor, and the flatness characteristics are deteriorated due to the dissolution of the low molecular compound. It becomes a cause of a decrease in voltage holding ratio or a scratch of a flat plate, which becomes a problem. When the amount exceeds 1 × 10 ⁶ , the viscosity when used as an alignment agent is too high, which causes a problem in coatability. Further, the molecular weight distribution (hereinafter referred to as "Mw/Mn". Mn represents a number average molecular weight in terms of polystyrene) is preferably 20.0 or less, more preferably 15.0 or less, and particularly preferably 10.0 or less. By reducing Mw/Mn, it is possible to obtain an alignment film which is excellent in coating property of an alignment agent and which does not cause a problem of deterioration of flatness characteristics due to elution of the above-mentioned low molecular compound.

The liquid crystal alignment agent of the present invention can be used as a liquid crystal alignment agent of various types such as a VA method, a TN method, an IPS method, an OCB method, or an FFS method, and can be used as an alignment agent for a preferred vertical alignment (VA) form. The repeating unit content of the pretilt angle display component represented by the above formula (1) when used as a VA alignment agent is preferably 4 to 60 mol %, more preferably 5 to 40% by mole, especially good for 6~30%. When the content of the pretilt angle display component represented by the formula (1) is less than 4 mol%, sufficient liquid crystal vertical alignment property cannot be exhibited, and if it is more than 60 mol%, the printability is deteriorated or easily Produces scorch marks associated with residual DC.

In the present invention, when the liquid crystal alignment film is provided with a high initial voltage holding ratio, when the liquid crystal panel is driven for a long period of time, or when heating or light pressure is applied for a long period of time, the voltage holding ratio is not changed with high reliability, and the composition has a pretilt angle display component. The acrylic polymer preferably contains a repeating unit having a cyclic ether structure represented by the above formula (2). The repeating unit content of the cyclic ether structure represented by the above formula (2) is, for example, 5 to 50 mol%, preferably 15 to 45 mol%, particularly preferably 20 to 40 mol%. When the repeating unit content of the cyclic ether structure represented by the above formula (2) is less than 5 mol%, the crosslinking reaction cannot be sufficiently obtained for the purpose of obtaining high reliability of the voltage holding ratio and the like. When the effect is more than 50% by mole, unreacted functional groups remain, which may deteriorate electrical characteristics and the like. Further, in order to promote the crosslinking reaction of the cyclic ether structure represented by the above formula (2), the acrylic polymer having a pretilt angle display component of the present invention may suitably contain a carboxy group represented by the above formula (5). Repeating unit of acid group. The content of the repeating unit of the carboxylic acid group represented by the formula (5) is almost the same as the repeating unit of the cyclic ether structure represented by the above formula (2), and for example, it contains 5 to 50 mol%. The best contains 15~45% of the mole, and the best contains 20~40%.

The structural unit shown in each of the above formula (6) and the above formula (7) can impart heat resistance to an acrylic polymer having a pretilt display component, and thus is suitable. It is preferably used, and each of them has the same molar amount, and is suitable for deactivating the repeating unit of the pretilt angle display component represented by the above formula (1) by the full amount of the polymer, and having the cyclic ether represented by the above formula (2). a repeating unit of the structure and a repeating unit having a carboxylic acid group represented by the above formula (5).

<Liquid alignment agent>

The liquid crystal alignment agent of the present invention is composed of at least one type of polymer having a structural unit represented by the above formula (1) and other additives as necessary, and is preferably dissolved in an organic solvent.

The organic solvent constituting the liquid crystal alignment agent of the present invention is the same as the solvent exemplified as the synthesis reaction of the acrylic polymer used in the pretilt display component represented by the above formula (1). Further, from the viewpoint of printability, a solvent having a boiling point of 160 ° C or higher is preferred. Examples of such solvents include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethyl hydrazine, γ-butyrolactone, tetramethyl urea, and hexamethylphosphorus. Indoleamine, m-cresol, xylenol, phenol, diacetone alcohol, ethylene glycol monobutyl ether (butyl glycol ethyl ether), propylene carbonate, diethylene glycol diethyl ether. The composition of the solvent is a composition obtained by combining the above solvents, which is a composition in which the liquid crystal alignment agent is not solid-formed, and the surface tension of the liquid crystal alignment agent is in the range of 25 to 40 mN/m.

The solid content concentration in the liquid crystal alignment agent of the present invention can be selected in consideration of viscosity, volatility, etc., and is, for example, 1 to 50% by weight, preferably 2 to 40% by weight, particularly preferably 3 to 30% by weight. The scope. That is, the liquid crystal alignment agent of the present invention is applied onto the surface of the substrate to form a liquid crystal alignment. When the film concentration is less than 1% by weight, the film thickness of the coating film is too small, and it is difficult to obtain a good liquid crystal alignment film. When the solid content concentration exceeds 50% by weight, the film thickness of the coating film is too large, and it is difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent is increased to deteriorate the coating property, and the in-plane uniformity cannot be obtained. Excellent liquid crystal alignment film.

Further, the range of the solid content concentration which is particularly preferable is different depending on the coating method used when the liquid crystal alignment agent is applied to the substrate, and more specifically, the viscosity of the liquid crystal alignment agent to be applied to each coating method is required, and the solid must be adjusted. Ingredient concentration. For example, in the case of using the spin coating method, the viscosity of the alignment agent is adjusted to 3.0 to 10.0 mPa. The range of s is good. In the case of using the printing method, the viscosity of the alignment agent is adjusted to 12 to 50 mPa. The range of s is good. When using the inkjet method, the viscosity of the alignment agent is 3~15mPa. The range of S is better.

Further, the temperature at which the liquid crystal alignment agent of the present invention is prepared is preferably 0 ° C to 200 ° C, more preferably 20 ° C to 60 ° C.

The liquid crystal alignment agent of the present invention is stored in a frozen state and sufficiently thawed to room temperature, and the number of particulate foreign matter having a size of 1.0 μm or more measured by using a microparticle counter is measured by a particle detector in a RION solution. The value is preferably 20 pieces/ml or less, more preferably 10 pieces/ml or less, and particularly preferably 5 pieces/ml or less. When the number of particulate foreign matter having a size of 1.0 μm or more is more than 20/ml, the aggregate of the foreign matter is generated in the liquid crystal alignment agent, and the aggregate becomes a pinhole or collapse of the liquid crystal alignment film.

In the liquid crystal alignment agent of the present invention, other additives may be added as necessary. As an additive, for example, from the viewpoint of improving residual DC and scratch resistance Polyhistamine is mentioned, and from the viewpoint of improving the voltage holding ratio, an imidized polymer can be mentioned, and from the viewpoint of improving the adhesion to the surface of the electrostatic gas or the surface of the substrate and improving the voltage holding ratio, The compound containing a functional decane or a low molecular compound having two or more epoxy groups in the molecule can be mentioned.

As the poly-prolinic acid and the imidized polymer which may be added as the liquid crystal alignment agent of the present invention, a synthetic polytheneamine obtained by polyaddition reaction of a tetracarboxylic dianhydride and a diamine compound may be mentioned. An acid and an imidized polymer obtained by imidization of the poly-proline. These may be contained alone or in combination of two or more. The so-called imidized polymer, which comprises a part of the polyimine acid imidized partial imine polymer and 100% imidized polymer, which are collectively referred to as "imidized polymer" . Further, the preferred imidization ratio in the imidized polymer used therein is from 10 to 100 mol%, more preferably from 20 to 95 mol%, particularly preferably from 45 to 90 mol%. Here, the "imidization ratio" is the total number of repeating units of the quinone imine and the repeating unit of the imine in the polymer, and the ratio of the number of repeating units of the imine is expressed by %. At this time, a part of the imine ring is an imine ring, and the number of repeating units contained in the imine is also included. Specific examples of the imidized acid which can be added to the liquid crystal alignment agent of the present invention and the imidized polymer obtained by imidization of the polypyridic acid include, for example, at least one selected from the group consisting of 1, 2 , 3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentane Tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 5-(2,5-dioxotetrahydrogen) -3-furan)-3-methyl-3-cyclohexane-1,2-dicarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furan)-naphtho[1,2-c]furan-1,3-di Ketone, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furan)-naphtho[1,2-c] Furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5,8-dimethyl-5-(tetrahydro-2,5-dioxo-3-furan) -naphtho[1,2-c]furan-1,3-dione, bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 3-oxobicyclo [3.2.1] Octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 3,5,6-tricarboxy-2-carboxynorbornane -2:3,5:6-dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3',4,4 '-benzophenone tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic acid An anhydride, 3,3',4,4'-biphenylfluorene tetracarboxylic dianhydride, tetracarboxylic dianhydride of 1,4,5,8-naphthalenetetracarboxylic dianhydride, and, for example, at least one selected from p -phenylene diamine, 4,4'-diamine diphenylmethane, 4,4 -diamine diphenyl sulfide, 1,5-diamine naphthalene, 2,7-diamine oxime, 4,4'-diamine diphenyl ether, 9,9-bis(4-aminophenyl) fluorene , 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-double (4-Aminophenyl)hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamine -2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diamine-2,2'-dimethylbiphenyl, 2,6-diamine pyridine, 3,4-diamine pyridine , 2,4-diaminopyrimidine, 3,6-diamine acridine, 1,3-bis(aminomethyl)cyclohexane, 1,4-cyclohexanediamine, 4,4'-methyl Bis(cyclohexylamine), 3,3'-(tetramethyldioxane-1,3-diyl) bis ( The polyimidic acid obtained by the reaction of the diamine of propylamine and the imidized polymer obtained by imidization of the poly-proline. Among them, at least one selected from the group consisting of 1,2,3,4-cyclobutane tetracarboxylic dianhydride and 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride , 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo- 3-furan)-naphtho[1,2-c]furan-1,3-dione, 3-oxobicyclo[3.2.1]octane-2,4-dione-6-spiro-3'-( a tetracarboxylic dianhydride of tetrahydrofuran-2',5'-dione), pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and at least one selected from the group consisting of P-phenylenediamine, 4,4'-diaminediphenylmethane, 2,7-diamine oxime, 4,4'-diamine diphenyl ether, 4,4'-diamine-2, Imidization of poly-proline and its poly-proline by imidization of 2'-dimethylbiphenyl and 1,3-bis(aminomethyl)cyclohexane diamine The polymer is preferred. The addition ratio shown by parts by weight of these polyimidic acid and imidized polymer is preferably (the total amount of the acrylic polymer having the pretilt angle display component of the present invention): (polyimmediate acid and imidization) The total amount of the polymer) = 10:90 to 90:10, preferably 20:80 to 80:20, and particularly preferably 30:70 to 70:30.

Examples of the compound containing a functional decane include 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 2-aminopropyltrimethoxydecane, and 2-aminopropyltriethyl. Oxydecane, N-(2-aminoethyl)-3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, 3-urea Propyltrimethoxydecane, 3-ureidopropyltriethoxydecane, N-ethoxycarbonyl-3-aminopropyltrimethoxydecane, N-ethoxycarbonyl-3-aminopropyltriethoxy Base decane, N -triethoxycarbamidopropyltriethylenetriamine, N-trimethoxyformamidopropyltriethylenetriamine, 10-trimethoxycarbamido-1,4,7-triazadecane , 10-triethoxycarbamido-1,4,7-triazadecane, 9-trimethoxycarbamido-3,6-diazadecyl acetate, 9-triethoxy Mercaptoalkyl-3,6-diazaindolyl acetate, N-benzyl-3-aminopropyltrimethoxydecane, N-benzyl-3-aminopropyltriethoxydecane , N-phenyl-3-aminopropyltrimethoxydecane, N-phenyl-3-aminopropyltriethoxydecane, 3-glycidoxypropyltrimethoxydecane, N-double ( Oxyethylene)-3-aminopropyltrimethoxydecane, N-bis(oxyethylene)-3-aminopropyltriethoxydecane, and the like. When these compounds containing a functional decane are used, the addition ratio thereof is preferably 2 parts by weight or less, more preferably 0.2 parts by weight or less, based on 100 parts by weight of the total amount of the polymer of the present invention.

Examples of the low molecular compound having two or more epoxy groups in the molecule include ethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, propylene glycol diepoxypropyl ether, and three. Propylene glycol diepoxypropyl ether, polypropylene glycol diepoxypropyl ether, neopentyl glycol diepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, glycerol diepoxypropyl Ether, 2,2-dibromoneopentyl glycol diepoxypropyl ether, 1,3,5,6-tetraepoxypropyl-2,4-hexanediol, N,N,N ',N'-tetraepoxypropyl-m-xylenediamine, 1,3-bis(N,N-diglycidylmethyl)cyclohexane, N,N,N',N'-four Epoxypropyl-4,4'-diaminediphenylmethane, N,N,N',N'-tetraepoxypropyl-p-phenylene diamine and the like are preferred examples. When a low molecular compound having two or more epoxy groups in the molecule is used, the ratio of addition ratio is added thereto. The total amount of the polymer of the present invention is preferably from 1 to 60 parts by weight, more preferably from 5 to 40 parts by weight, even more preferably from 10 to 30 parts by weight, based on 100 parts by weight of the total amount of the polymer.

<Liquid crystal display element>

The liquid crystal display element of the present invention can be produced, for example, by the following method.

(1) The liquid crystal alignment agent of the present invention is applied to a substrate surface on which a patterned transparent conductive film is provided, for example, by a roll coating method, a spin coating method, a printing method, an inkjet method, or the like. Next, a coating film is formed by heating the coated surface. In addition, as the substrate, for example, glass such as floating glass or soda lime glass can be used; and polyethylene terephthalate, polybutylene terephthalate, polyether oxime, polycarbonate, or fat can be used. A transparent substrate made of plastic such as a cyclic polyolefin. As the transparent conductive film provided on the surface of the substrate, a NESA film (registered trademark of PPG, USA) and indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) made of tin oxide (SnO ₂ ) can be used. ITO film, etc. The pattern of the transparent conductive films forms a method that can be used by photolithography or a pre-mask. As the reflective electrode, a metal such as A1 or Ag or an alloy of the same may be used. However, it is not particularly limited as long as it has sufficient reflectance. When the liquid crystal alignment agent is applied, it is desired to further improve the adhesion between the surface of the substrate and the transparent conductive film or the reflective electrode and the liquid crystal alignment film, and the compound containing the functional decane may be applied to the surface of the substrate in advance. A compound of a functional titanium or the like. After the liquid crystal alignment agent is applied, preliminary heating (prebaking) is generally performed for the purpose of preventing bleeding of the alignment agent after coating. The pre-baking temperature is preferably 30 to 300 ° C, more preferably 40 to 200 ° C, and particularly preferably 50 to 150 ° C. Thereafter, the solvent is completely removed, and when the polymer contains a cyclic ether structure, a calcination (post-grilling) step can be carried out for the purpose of promoting the thermal crosslinking reaction of the functional group. The firing (post-grill) temperature is preferably from 80 to 300 ° C, more preferably from 120 to 250 ° C. Thereby, the liquid crystal alignment agent of the present invention can form a coating film formed by a liquid crystal alignment film by removing an organic solvent after coating. The film thickness of the liquid crystal alignment film formed is preferably 0.001 to 1 μm, more preferably 0.005 to 0.5 μm.

(2) The surface of the coating film formed as necessary, for example, a cloth made of fibers such as nylon, rayon, or cotton is taken up into a cylindrical shape, and subjected to rubbing treatment in a predetermined direction. Thereby, a liquid crystal alignment film whose alignment energy or pretilt angle of the liquid crystal molecules is controlled can be obtained. Further, in addition to the method of rubbing treatment, a method of controlling the alignment energy by irradiating the surface of the coating film with polarized ultraviolet light can also be applied. Further, it is preferable to remove the fine powder (foreign matter) generated during the rubbing treatment to clean the surface of the coating film, and to form the liquid crystal alignment film to be washed with isopropyl alcohol and/or pure water. Further, the liquid crystal of the present invention is subjected to partial irradiation with ultraviolet rays as disclosed in JP-A-6-222366 or JP-A-6-281937, and the pretilt angle is changed. The photoresist film is partially formed on the rubbed liquid crystal alignment film, and the rubbing film is removed in a direction different from the preceding rubbing treatment, and the photoresist film is removed, as disclosed in Japanese Laid-Open Patent Publication No. H5-107544. The processing of the alignment of the liquid crystal alignment film can be performed to improve the visual field characteristics of the liquid crystal display element.

(3) Producing two substrates formed by the above liquid crystal alignment film, and the rubbing direction of each liquid crystal alignment film is orthogonal or antiparallel, and 2 substrates are The cells are arranged in a direction opposite to each other, and the peripheral portions of the two substrates are bonded together by a sealing agent, and a liquid crystal is filled in a gap defined by the surface of the substrate and the sealing agent to seal the injection holes. Liquid crystal cell. On the outer surface of the liquid crystal cell, that is, on the outer side of each of the substrates constituting the liquid crystal cell, a liquid crystal display element is obtained by disposing a polarizing plate.

Among them, as the sealing agent, for example, a curing agent and an epoxy resin containing an alumina ball as a spacer can be used.

Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Further, a nematic liquid crystal is preferable, and for example, a Schiff base liquid crystal, an oxidized azo liquid crystal, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, a triphenyl liquid crystal, or a combination can be used. A benzocyclohexane liquid crystal, a pyrimidine liquid crystal, a dioxane liquid crystal, a bicyclooctane liquid crystal, a cuba liquid crystal, or the like. Further, a cholesteric liquid crystal such as chlorinated gallbladder, cholestyl phthalate or cholestyl carbonate may be added to the liquid crystal, or the product name "C-15" or "CB-15" (manufactured by Merck) may be added. Used after the sale of palmar reagents. Further, a ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amine-2-methylbutylcinnamate may be used.

In addition, as a polarizing plate which is bonded to the outer surface of the liquid crystal cell, a polarizing plate in which a polyvinyl alcohol is stretched downward and a polarizing film which absorbs iodine and is called an H film is held by a cellulose acetate protective film, or the H film itself is exemplified. The resulting polarizer.

As described above, the liquid crystal alignment agent of the present invention imparts good coating properties to the liquid crystal panel, and even if light or heat is applied to the liquid crystal panel or the liquid crystal panel is driven for a long period of time, the liquid crystal which does not cause a decrease in voltage holding ratio or a scorch is generated. A liquid crystal alignment agent for an alignment film.

Example

Hereinafter, the present invention will be more specifically illustrated by the examples, but the present invention is not limited to the examples. The measurement of the molecular weight of the polymer in the examples and the comparative examples, the coating property of the liquid crystal alignment agent, the measurement of the number of fine particles, and the reliability of the pretilt angle, the voltage holding ratio, and the voltage holding ratio of the liquid crystal display device produced were determined according to the following methods. Evaluation.

[Weight average molecular weight and molecular weight distribution] Gel permeation chromatography (GPC, manufactured by Tosoh Co., Ltd., trade name: HLC-8020/column 3: manufactured by Tosoh), trade name: TSK guardcolum α, TSK gel α-M, TSK gel α -2500), using dimethylformamide (DMF; adding lithium bromide, 9.4 g of monohydrate and 1.7 g of phosphoric acid to DMF3L) as a solvent, and measuring the weight average molecular weight (Mw) in terms of polystyrene, and Molecular weight distribution (Mw/Mn). And Mn is a number average molecular weight.

[Coating property of liquid crystal alignment agent] Using a JET-CM continuous inkjet printer (manufactured by Kishu Techno Co., Ltd.), an ITO film having a film thickness of 200 nm and a width of 20 μm was formed on a stripe-shaped ITO substrate at intervals of 100 μm to dry the film to a thickness of 60 nm. The coating of the liquid crystal alignment agent was carried out in an amount. The obtained liquid crystal alignment agent coating base The plate was pre-baked (hot plate) at 80 ° C for 1 minute, and then baked at 200 ° C for 60 minutes (in a dust-free oven, under a nitrogen atmosphere), and the peripheral portion and the central portion of the liquid crystal alignment film were 20 times. When the microscope was observed, it was judged as "good" when no coating unevenness was observed, and it was judged as "poor" when pinhole or uneven coating (uneven film thickness) was observed. The results of evaluation of the coatability of each alignment agent are summarized in Table 1.

[number of particles] Using a liquid particle detector (KL-20A manufactured by RION Co., Ltd.), the number of particles having a size of 1.0 μm or more of 10 ml of the liquid crystal alignment agent was measured twice, and the average value was defined as the number of particles having a size of 1.0 μm or more. The measurement was carried out under the conditions of a light source wavelength of 780 nm and a sample suction speed of 10 ml/min.

[pretilt angle] The pretilt angle measurement of the liquid crystal display element was carried out using a central precision machine (strand) coordinate strength measuring device OMS-J3.

[Voltage retention rate] The liquid crystal display element was charged with a voltage of 5 V for 60 microseconds, and after 167 milliseconds, the voltage retention after the release to 167 milliseconds was measured in an environment of 60 °C. The measuring device was a VHR-1 manufactured by Toyo Technica. When the voltage holding ratio was 99.0% or more, it was judged as "good", and the other cases were judged as "poor".

[reliability of voltage retention rate] The prepared liquid crystal display element was stored in an oven at 100 ° C for 7 days, and subjected to hot pressure. The voltage holding ratio before and after the hot pressure was measured. When the absolute value of the change in the voltage holding ratio is within 0.5%, it is judged as "good", and the other cases are judged as "poor".

80 g of β-cholestyl alcohol was dissolved in 800 ml of dehydrated tetrahydrofuran (THF), and after adding 27.2 g of triethylamine, 35.6 g of propylene chloride was gradually added dropwise, and the mixture was stirred at room temperature (r.t.) for 3 hours. After the completion of the reaction, triethylamine hydrochloride was removed by filtration, and THF was evaporated under reduced pressure, and then 400 ml of chloroform was added. The solution was washed with water, and the organic layer was dried over magnesium sulfate, and then chloroform was removed by distillation under reduced pressure. Thereafter, recrystallization was carried out by ethanol to obtain 54 g of a cholesteryl methacrylate as a white solid represented by the above reaction formula (yield: 57.4%).

Synthesis Example 2 (Synthesis of Polymer A) The cholesteryl methacrylate obtained in Synthesis Example 1 as a monomer was placed in a four-necked flask equipped with a stir bar, a three-way stopcock, and a thermometer (15.16 g ( 0.0332 mol), epoxy methacrylate 12.8 g (0.09 mol), 7.2 g (0.0836 mol) of methacrylic acid, 7.2 g (0.0691 mol) of styrene, N-cyclohexyl maleic anhydride 7.2 g (0.0402 mol) of imine, adding 52.8 g of diethylene glycol ethyl methyl ether as a solvent, 2,2'-azobis(2,4-dimethylpentyl) as a polymerization initiator 2.72 g of an α-methylstyrene dimer as a chain shifting agent of 0.96 g. This was bubbled under a nitrogen stream for about 10 minutes and replaced with nitrogen in the system, and then reacted at 70 ° C for 5 hours in a nitrogen atmosphere to obtain a polymer A having a pretilt display component. After the molecular weight of the polymer A was measured by GPC, Mw = 96,000 and Mw / Mn = 7.87, and peaks due to residual monomers were not confirmed. In the present polymer solution, it is assumed that the charged monomer has been completely converted into the polymer A, and the liquid crystal alignment agent used in the present invention is directly diluted.

Synthesis Example 3 (Synthesis of Polymer B) The polymer B having a pretilt angle display component was obtained in the same manner as in Synthesis Example 2 except that N-cyclohexylmaleic anhydride imide was used in an amount of 7.2 g (0.0416 mol) of N-phenylmaleic anhydride. After the molecular weight of the polymer B was measured by GPC, Mw = 108,000 and Mw / Mn = 6.51, and peaks due to residual monomers were not confirmed. In the present polymer solution, it is assumed that the charged monomer has been completely converted into the polymer B, and the liquid crystal alignment agent used in the present invention is directly diluted.

Synthesis Example 4 (Synthesis of Polymer C) Filled with cholesteryl methacrylate 30.0 g (0.0657 mol), epoxy propyl methacrylate 12.0 g (0.0844 mol), methacrylic acid 7.0 g (0.0813 mol), styrene 4.5 g (0.0432 Mo) Ear), N-cyclohexylmaleic anhydride imide 7.2 g (0.0402 mol), further using 65.0 g of diethylene glycol ethyl methyl ether as a solvent, 2,2'-couple as a polymerization initiator The pre-tilt display component was obtained in the same manner as in Synthesis Example 2 except that 2.74 g of nitrogen bis(2,4-dimethylvaleronitrile) and 1.18 g of α-methylstyrene dimer as a chain-linking agent were used. Polymer C. After the molecular weight of the polymer C was measured by GPC, Mw was 79,000 and Mw/Mn was 7.31, and peaks due to residual monomers were not confirmed. In the present polymer solution, it is assumed that the charged monomer has been completely converted into the polymer C, and the liquid crystal alignment agent used in the present invention is directly diluted.

Synthesis Example 5 (Synthesis of Polymer D) Filled with cholesteryl methacrylate 10.0 g (0.0219 mol), epoxy propyl methacrylate 15.0 g (0.1055 mol), methacrylic acid 9.0 g (0.1045 mol), styrene 2.5 g (0.0240 mol) Ear), N-cyclohexylmaleic anhydride imide 4.0g (0.0223 mol), further using 43.0 g of diethylene glycol ethyl methyl ether as a solvent, 2,2'-couple as a polymerization initiator A pre-tilt display component was obtained in the same manner as in Synthesis Example 2 except that 1.83 g of nitrogen bis(2,4-dimethylvaleronitrile) and 0.78 g of α-methylstyrene dimer as a chain-linking agent were used. Polymer D. After the molecular weight of the polymer D was measured by GPC, Mw = 125,000 and Mw / Mn = 9.54, and peaks due to residual monomers were not confirmed. Benju In the solution of the solution, it is assumed that the charged monomer has been completely converted into the polymer D, and the liquid crystal alignment agent used in the present invention is directly diluted.

Comparative Synthesis Example 1 (synthesis of polymer E) In a four-necked flask equipped with a stir bar, a three-way stopcock, and a thermometer, 40.0 g (0.2814 mol) of propylene glycol methacrylate as a monomer, 20.0 g (0.2323 mol) of methacrylic acid, and styrene were charged. 20.0 g (0.192 mol), N-cyclohexylmaleic anhydride imide 20.0 g (0.1116 mol), further added as a solvent, diethylene glycol ethyl methyl ether 132.0 g, as a starter 2 2,0--azobis(2,4-dimethylpentyl) 7.00 g, 3.00 g of α-methylstyrene dimer as a chain-linking agent. This was foamed in a nitrogen stream for about 10 minutes, and nitrogen substitution in the system was carried out, followed by a reaction at 70 ° C for 5 hours in a nitrogen atmosphere to obtain a polymer E. After the molecular weight of the polymer E was measured by GPC, Mw = 91,000 and Mw / Mn = 11.86, and peaks due to residual monomers were not confirmed. In the present polymer solution, it is assumed that the charged monomer has been completely converted into the polymer E, and the liquid crystal alignment agent used in the present invention is directly diluted.

20.8381 g (0.0930 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride as tetracarboxylic dianhydride, 9.2129 g (0.0852 mol) of p-phenylenediamine as a diamine compound 4.9490 g (0.0095 mol) of the diamine represented by the above formula (a) was dissolved in 140 g of N-methyl-2-pyrrolidone, and the reaction was carried out at 60 ° C for 5 hours. Next, the reaction solution was poured into a large amount of excess methanol to precipitate a reaction product. Thereafter, the mixture was washed with methanol, and dried under reduced pressure at 40 ° C for 24 hours to obtain 31 g of polylysine. 30 g of the obtained poly-proline was dissolved in 400 g of N-methyl-2-pyrrolidone, 6.3 g of pyridinium and 8.1 g of acetic anhydride were added, and dehydration ring closure was carried out at 110 ° C for 4 hours, and precipitation and washing were carried out in the same manner as above. Drying under reduced pressure gave an imidized polymer F (26 g, Mw = 111,000, Mw / Mn = 5.23, and an imidation ratio of 51%).

Comparative Synthesis Example 3 (synthesis of polymer G) 19.8781 g (0.0887 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride as tetracarboxylic dianhydride, 6.8285 g (0.0631 mol) of p-phenylenediamine as a diamine compound, 3.5771 g (0.0180 mol) of diamine diphenylmethane and 4.7162 g (0.0090 mol) of the diamine represented by the above formula (a) were dissolved in 140 g of N-methyl-2-pyrrolidone, and reacted at 60 ° C for 4 hours. . Next, the reaction solution was poured into a large amount of excess methanol to precipitate a reaction product. Thereafter, the mixture was washed with methanol, and dried under reduced pressure at 40 ° C for 24 hours to obtain 32.8 g of polyimide. 30 g of the obtained poly-proline was dissolved in 400 g of N-methyl-2-pyrrolidone. 12.0 g of pyridine and 15.5 g of acetic anhydride were added, and dehydration ring closure was carried out for 4 hours at 110 ° C, and precipitation, washing, and drying under reduced pressure were carried out in the same manner as above to obtain Mw = 92,000, Mw / Mn = 4.19, and imidization ratio of 79%. The imidized polymer G 25g.

Example 1 Diethylene glycol methyl ethyl ether was further added to the polymer A solution obtained in Synthesis Example 2 as a liquid crystal alignment agent having a total solid content of 3.5% by weight. After sufficiently stirring the mixture, it was filtered using a filter having a pore size of 0.2 μm to obtain a liquid crystal alignment agent of the present invention. After the obtained liquid crystal alignment agent was stored in a freezer at -15 ° C for 7 days, the alignment agent was thawed to room temperature, and the measurement of the number of fine particles and the coating property test were carried out. The results are shown in Table 1. Further, a VA liquid crystal display element was produced as follows, and the reliability evaluation of the pretilt angle, the voltage holding ratio, and the voltage holding ratio was performed. The liquid crystal alignment agent of the present invention is coated on a transparent conductive film made of an ITO film on one surface of a glass substrate, and is coated with a spinner, and then preliminarily dried at 80 ° C for 1 minute on a hot plate, followed by a dust-free oven ( In a nitrogen atmosphere, firing was performed at 200 ° C for 1 hour to prepare a transparent electrode substrate having a liquid crystal alignment film having a film thickness of 60 nm. Next, after coating an epoxy resin adhesive having an alumina ball having a diameter of 5.5 μm on each outer edge of the liquid crystal alignment film of the liquid crystal alignment film coating substrate having a pair of transparent electrode/transparent electrode substrates, The film is laminated and pressed against the liquid crystal alignment film surface to harden the adhesive. Next, a negative liquid crystal (manufactured by Merck, MLC-2038) was filled between the substrates by a liquid crystal injection port, and then sealed with an acrylic photocurable adhesive. In the liquid crystal injection port, a polarizing plate was bonded to both sides of the substrate to produce a VA liquid crystal display element. The obtained VA type liquid crystal display device was evaluated for reliability of pretilt angle, voltage holding ratio, and voltage holding ratio, and the results are shown in Table 1.

Example 2 The liquid crystal alignment agent and the VA liquid crystal display element of the present invention were obtained in the same manner as in Example 1 except that the polymer B solution obtained in Synthesis Example 3 was used instead of the polymer A solution. The results of evaluating the reliability of the number of particles, the coatability, the pretilt angle, the voltage holding ratio, and the voltage holding ratio are shown in Table 1.

Example 3 The liquid crystal alignment agent and the VA liquid crystal display element of the present invention were obtained in the same manner as in Example 1 except that the polymer C solution obtained in Synthesis Example 4 was used instead of the polymer A solution. The results of evaluating the reliability of the number of particles, the coatability, the pretilt angle, the voltage holding ratio, and the voltage holding ratio are shown in Table 1.

Example 4 The liquid crystal alignment agent of the present invention and the VA liquid crystal display element were obtained in the same manner as in Example 1 except that the polymer D solution obtained in Synthesis Example 5 was used instead of the polymer A solution. The results of evaluating the reliability of the number of particles, the coatability, the pretilt angle, the voltage holding ratio, and the voltage holding ratio are shown in Table 1.

Comparative example 1 The liquid crystal alignment agent and the liquid crystal display element of the present invention were obtained in the same manner as in Example 1 except that the polymer E solution obtained in Comparative Synthesis Example 1 was used. The results of evaluating the reliability of the number of particles, the coatability, the pretilt angle, the voltage holding ratio, and the voltage holding ratio are shown in Table 1.

Comparative example 2 Adding the weight ratio of N-methyl-2-pyrrolidone to ethylene glycol monobutyl ether to N-methyl-2-pyrrolidone/ethylene glycol monobutyl ether in the polymer F obtained in Comparative Synthesis Example 2 = 50 /50, further adding N, N, N', N'-tetra-glycidyl-4,4'-diamine diphenylmethane to 20% by weight of the polymer F to form an all solid concentration of 3.5% by weight Liquid crystal alignment agent. A liquid crystal alignment agent and a VA liquid crystal display element of the present invention were obtained in the same manner as in Example 1 except the above. The results of evaluating the reliability of the number of particles, the coatability, the pretilt angle, the voltage holding ratio, and the voltage holding ratio are shown in Table 1.

Comparative example 3 To compare the polymer G obtained in Synthesis Example 3, γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether to γ-butyrolactone/N-methyl-2-pyrrolidone/B Glycol monobutyl ether mixed weight ratio = 40/30/30, and then added N, N, N', N'-tetraepoxypropyl-4,4'-diamine diphenylmethane to the polymer G At 20% by weight, a liquid crystal alignment agent having a total solid concentration of 3.5% by weight was prepared. A liquid crystal alignment agent and a VA liquid crystal display element of the present invention were obtained in the same manner as in Example 1 except the above. Letter to evaluate particle count, coatability, pretilt angle, voltage hold rate, and voltage hold rate The results of the dependence are shown in Table 1.

In the above Table 1, it is understood that the liquid crystal alignment films obtained by the liquid crystal alignment agents of the present invention obtained in Examples 1 to 4 can simultaneously achieve excellent coating properties of the alignment film, higher voltage holding ratio, and voltage holding ratio. Excellent reliability. On the other hand, it is known from the comparative examples that the conventional alignment agent cannot simultaneously satisfy the above characteristics. The above characteristics of the liquid crystal alignment agent of the present invention can be optimized by the structure selection and the content of the content in the repeating structural unit formed by the pretilt display component represented by the formula (1), and the structure selection in other copolymerized components and The adjustment of the content is optimized. As described above, according to the present invention, it is possible to provide a liquid crystal alignment agent which imparts excellent alignment agent coating property, high voltage holding ratio, and excellent voltage stability to a liquid crystal alignment film, and a beautiful image having the liquid crystal alignment film. Liquid crystal display element.

Claims (8)

A liquid crystal alignment agent characterized by containing a polymer having a repeating unit represented by the following formulas (1), (2), and (5); (wherein R ₁ is a hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; or a monovalent polar group; A ₁ is a single bond or an alkylene group having 1 to 10 carbon atoms, and A ₂ , A ₃ and A _{4 are} each independently a single bond, an ether bond (-O-), a carbonyl group (-CO-), or a carbonyloxy group ( -COO-), oxycarbonyl (-OCO-), guanamine bond (-NHCO-, -CONH-), thioether bond (-S-) or alkylene group having a carbon number of 1 to 10, B ₁ , B ₂ And B _{3 are} each independently a single bond, 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,2-cyclohexyl, 1,3-cyclohexyl, 1 , 4-cyclohexyl or piperidine-1,4-diyl, R ₂ is a hydrogen atom, a hydrocarbon group having 1 to 50 carbon atoms or a group containing a fluorine atom, but adjacent to A ₁ to A ₄ and B ₁ ~ When B ₃ is a single bond, it represents a single bond, and when A ₁ ~A ₄ and B ₁ ~B _{3 both} represent a single bond, R _{2 is} not a hydrogen atom); (wherein R ₃ is a hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group of an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom; or a monovalent polar group; , R ₄ is a single bond or a divalent organic group, and R ₅ is a group having a cyclic ether structure having a carbon number of 2 to 10); (wherein, R _{8 has} the same definition as R ₁ of the formula (1)). The liquid crystal alignment agent of claim 1, wherein R ₂ in the formula (1) is a linear or branched alkyl group having 6 to 50 carbon atoms or a group having a steroid skeleton. The liquid crystal alignment agent of claim 1, wherein R ₅ of the formula (2) is a group having an epoxy group structure or an oxetane structure. The liquid crystal alignment agent of claim 1, wherein the repeating unit represented by the formula (1) is a repeating unit represented by the following formula (3); (wherein, the definition of R _{6 is} the same as the definition of R ₁ of the formula (1)). The liquid crystal alignment agent of claim 1, wherein the repeating unit represented by the formula (2) is a repeating unit represented by the following formula (4); (wherein, the definition of R _{7 is} the same as the definition of R ₁ of the above formula (1), and a is an integer of 1 to 10). The liquid crystal alignment agent of claim 4 or 5, wherein the polymer further contains at least one of repeating units represented by the following formulas (6) and (7); (wherein R ₉ is a substituted or unsubstituted hydrocarbon group having 1 to 50 carbon atoms which may have a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a ruthenium atom, and R ₁₀ and R _{11 are} each independently of the above formula ( 1) The definition of R _{1 is} the same). A liquid crystal alignment film characterized by being formed by a liquid crystal alignment agent according to any one of claims 1 to 6. A liquid crystal display element comprising the liquid crystal alignment film of item 7 of the patent application.