TWI504727B - Liquid crystal alignment agent, liquid crystal alignment film, mtrhod of forming liquid crystal alignment film, and liquid crystal display device - Google Patents

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal alignment film forming method And liquid crystal display elements

The present invention relates to a liquid crystal alignment agent suitable for photoalignment, a liquid crystal alignment film, a method for forming a liquid crystal alignment film, and a liquid crystal display element.

Liquid crystal displays (LCDs) are widely used in televisions or various displays. The display elements of the LCD include liquid crystal cells such as a twisted nematic (TN) type, a super twisted nematic (STN) type, and an in plan switching (IPS) type. In the case of changing the electrode structure of the IPS type, the fringe field switching (FFS) type, etc., which improves the numerical aperture of the display element portion and improves the brightness (refer to Japanese Patent Laid-Open No. Hei 56-91277 and Japanese Patent Laid-Open No. -120528).

A method of aligning the liquid crystal of such a liquid crystal cell is known in which a method of rubbing treatment is used, that is, an organic film such as a liquid crystal alignment film is formed on the surface of the substrate, and the surface of the organic film is rubbed in one direction by a cloth such as rayon. a method of obliquely vaporizing ruthenium oxide on the surface of a substrate; a method of forming a monomolecular film having a long-chain alkyl group by using the Langmuir-Blodget method (LB method); by including polyvinyl cinnamate (polyvinyl) A photo-alignment method in which a photosensitive film such as a polyimine resin or a polyamic acid is irradiated with a polarized or non-polarized radiation to impart a liquid crystal alignment ability (refer to Japanese Laid-Open Patent Publication No. Hei 6-287453, Japanese Patent Laid-Open No. 2003-307736 and Japanese Patent Japanese Laid-Open Patent Publication No. Hei 9-297313, and the like.

In these methods, the development of the above-described optical alignment method which does not generate static electricity or dust, achieves uniform liquid crystal alignment, and can precisely control the liquid crystal alignment direction is progressing. According to this light alignment method, a plurality of regions having different liquid crystal alignment directions can be arbitrarily formed on one substrate by using a photomask or the like when irradiating the radiation. However, the prior photo-alignment method using a polyimide resin, poly-plycine or the like has the following disadvantages: sensitivity is not sufficient, and a large cumulative exposure amount is required.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. SHO 56-91277

[Patent Document 2] Japanese Patent Laid-Open No. Hei 1-120528

[Patent Document 3] Japanese Patent Laid-Open No. Hei 6-287453

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2003-307736

[Patent Document 5] Japanese Patent Laid-Open No. Hei 9-297313

An object of the present invention is to provide a liquid crystal alignment agent which is excellent in radiation sensitivity and exhibits good liquid crystal alignment in a photo-alignment method having a low irradiation amount. Further, a method for forming a liquid crystal alignment film using such a liquid crystal alignment agent and a liquid crystal alignment film are provided, and a liquid crystal display element including the liquid crystal alignment film and having excellent electrical properties other than liquid crystal alignment properties is provided, and further provided as the liquid crystal. A compound of a material of an alignment agent.

In order to solve the above problems, the invention is a liquid crystal alignment agent comprising: [A] a polymer having a structural unit (I) comprising a group represented by the following formula (1) or a group represented by the formula (2) (hereinafter also referred to as "[A] polymer");

(In the formula (1), R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group; X is an oxygen atom or a sulfur atom; and in the formula (2), R ³ and R ⁴ are each independently a hydrogen atom or a monovalent group. Organic base).

Since the liquid crystal alignment agent of the present invention contains the [A] polymer having a specific structure as described above, the radiation sensitivity is high, and as a result, a liquid crystal alignment film having a good liquid crystal alignment property can be formed with a low irradiation amount. Moreover, the reason why the radiation sensitivity is made higher by the [A] polymer containing the above-described group having a specific structure is not necessarily clear, and can be estimated, for example, as follows. [A] The polymer has a cyclobutane skeleton represented by the above formula (1), and thus [A] polymerization is produced, for example, due to a Diels-Alder reaction. The main chain of the object is decomposed to generate light alignment due to polarized light with high sensitivity. In addition, due to the steric hindrance caused by the benzene ring bonded to the above-mentioned cyclobutane skeleton, it becomes easier to produce uniform optical alignment, and as a result, it becomes possible to achieve excellent irradiation with less irradiation amount. Light alignment. As described above, the liquid crystal alignment agent can reduce the amount of radiation irradiation necessary for light alignment, and thus cost reduction can be achieved. In addition, when a liquid crystal alignment film formed of the liquid crystal alignment agent is used, a liquid crystal display element having excellent electrical properties and the like can be produced.

The [A] polymer is preferably a polyester (hereinafter also referred to as "polyester (A1)") or a polythioester (hereinafter also referred to as "polythioester (A2)").

The structural unit (I) is preferably a structural unit represented by the following formula (3), formula (4) or formula (5).

[Chemical 2]

(In the formulas (3) to (5), R ¹ , R ² and X are synonymous with the above formula (1). Y ¹ to Y ³ are each independently a divalent organic group)

This liquid crystal alignment agent can have a light sensitivity of higher sensitivity because the [A] polymer has the structural unit (I) of the above specific structure.

The liquid crystal alignment agent of the present invention is suitably used for photoalignment. The liquid crystal alignment agent has high sensitivity to radiation and can form a liquid crystal alignment property with a low irradiation amount of radiation. Liquid crystal alignment film.

The method for forming a liquid crystal alignment film of the present invention comprises the following steps: (1) a step of forming a coating film on a substrate using the liquid crystal alignment agent of the present invention, and (2) A step of irradiating the coating film with polarized ultraviolet rays to impart alignment ability to the liquid crystal.

According to the formation method of the present invention, the light alignment can be performed even with a small amount of radiation irradiation, so that the liquid crystal alignment film can be efficiently produced, and the productivity is high and the manufacturing cost can be reduced.

The present invention also encompasses a liquid crystal alignment film formed of the liquid crystal alignment agent. Since the liquid crystal alignment film of the present invention is formed of the liquid crystal alignment agent, the sensitivity to radiation is high, and in the step of forming the liquid crystal alignment ability can be imparted by using a low irradiation amount of radiation, the production efficiency is good and the manufacturing cost can be improved. Get cuts.

The liquid crystal display element of the present invention comprises the liquid crystal alignment film. Since the liquid crystal display element includes the liquid crystal alignment film having excellent radiation sensitivity and liquid crystal alignment, it can be manufactured at a lower cost than before, and performance such as electrical characteristics can be sufficiently maintained.

The polymer of the present invention has a structural unit represented by the following formula (3).

[Chemical 3]

(In the formula (3), R ¹ and R ² each independently represent a hydrogen atom or a monovalent organic group. x is an oxygen atom or a sulfur atom. Y ¹ is a divalent organic group)

Since the polymer of the present invention has the above specific structure, it can be suitably used as the [A] polymer in the liquid crystal alignment agent, and the liquid crystal alignment agent containing the polymer of the present invention has high sensitivity to radiation and can be irradiated low. The amount of radiation forms a liquid crystal alignment film having excellent liquid crystal alignment energy.

In addition, "light" in "for optical alignment" is used synonymously with "radiation", and is a concept including visible light rays, ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams, and the like.

Since the liquid crystal alignment agent of the present invention has high radiation sensitivity and can form a liquid crystal alignment film having excellent liquid crystal alignment properties by radiation irradiation with a low irradiation amount, the production efficiency is high and the production cost can be reduced. In addition, the liquid crystal display element including the liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention is excellent in electrical properties and the like. Therefore, the liquid crystal alignment agent, the liquid crystal alignment film, the method for forming the liquid crystal alignment film, and the liquid crystal display element of the present invention can be suitably used for liquid crystals such as IPS type and FFS type. In the display component.

The above described features and advantages of the present invention will be more apparent from the following description.

<Liquid alignment agent>

The liquid crystal alignment agent of the present invention contains a [A] polymer having a structural unit (I) in a main chain, and the structural unit (I) contains a group represented by the above formula (1) or a group represented by the formula (2). Since the liquid crystal alignment agent contains the [A] polymer having the above-described specific structure, the radiation sensitivity is improved, and a liquid crystal alignment film having excellent liquid crystal alignment properties can be formed with a low irradiation amount of radiation. Further, the liquid crystal display element having the liquid crystal alignment film is excellent in electrical properties and the like. The liquid crystal alignment agent of the present invention may contain other components in addition to the essential component [A] polymer as long as the effects of the present invention are not impaired. Hereinafter, each component will be described in detail.

<[A]polymer>

The [A] polymer is a polymer having a structural unit (I). The polymer [A] is not particularly limited as long as it is a polymer having the above structural unit (I), and is preferably a polyester (A1) or a polythioester (A2). [A] The polymer is the polyester (A1) or the polythioester (A2) having the above structural unit (I), and therefore the liquid crystal alignment agent can form a liquid crystal alignment film having excellent liquid crystal alignment.

[Structural unit (I)]

The structural unit (I) includes the group represented by the above formula (1) or the formula (2) The base represented.

In the above formula (1), R ¹ and R ² each independently represent a hydrogen atom or a monovalent organic group. X is an oxygen atom or a sulfur atom.

In the above formula (2), R ³ and R ⁴ each independently represent a hydrogen atom or a monovalent organic group.

Examples of the monovalent organic group represented by the above R ¹ to R ⁴ include a chain hydrocarbon having 1 to 10 carbon atoms, an alicyclic hydrocarbon having 3 to 10 carbon atoms, and a carbon number of 6 An aromatic hydrocarbon group of ~10, a group in which these groups are combined with a hetero atom, and the like.

Examples of the chain hydrocarbon group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, and an isopenic group. Base.

Examples of the alicyclic hydrocarbon group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

Examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.

Examples of the above hetero atom include an oxygen atom, a sulfur atom, and a nitrogen atom.

R ¹ to R ^{4 are} preferably a hydrogen atom, a chain hydrocarbon group having 1 to 10 carbon atoms, and an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and more preferably a hydrogen atom.

X is preferably an oxygen atom.

The structural unit (1) is not particularly limited as long as it is a structural unit containing a group represented by the above formula (1) or a group represented by the formula (2), and is preferably represented by the above formulas (3) to (5). Structural unit, more preferably A structural unit represented by the formula (3).

In the above formulas (3) to (5), R ¹ , R ² and X have the same meanings as in the above formula (1). Y ¹ to Y ³ are each independently a divalent organic group.

Examples of the divalent organic group represented by the above Y ¹ to Y ³ include a divalent chain hydrocarbon group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 2 carbon atoms having 6 to 20 carbon atoms. a valent aromatic hydrocarbon group, a group in which these groups are combined with a hetero atom, and the like.

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include a methylene group, an ethanediyl group, a propanediyl group, a butyldiyl group, a pentanediyl group, a hexamethylene group, and a octyldiyl group.

Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentadienyl group, a cyclohexanediyl group, and a cyclooctyldiyl group.

Examples of the divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include phenylene, naphthylene, and anthracenylene.

The hetero atom which the divalent organic group represented by the above Y ¹ to Y ³ may have includes an oxygen atom, a sulfur atom, a nitrogen atom and the like. Among these, an oxygen atom is preferred.

The above Y ¹ to Y ^{3 are} preferably a divalent chain hydrocarbon group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms combined with a hetero atom. The group to be formed is more preferably a group in which a divalent chain hydrocarbon group having 1 to 20 carbon atoms is combined with a hetero atom, and more preferably a combination of a divalent chain hydrocarbon group having 2 to 4 carbon atoms and an oxygen atom. The group is particularly preferably a group represented by -CH ₂ -O-(CH ₂ ) _n -O-CH ₂ -. Where n is an integer from 1 to 10.

The content of the structural unit (I) in the polymer is preferably 10 mol% or more and 100 mol% or less, more preferably 60 mol% or more and 100 mol% or less, still more preferably 80 mol% or more and 100 mol% or less, and particularly preferably 90 mol%. Above 100 mol% or less. By setting the content of the structural unit (I) in the [A] polymer to the above specific range, the liquid crystal alignment agent can further improve the radiation sensitivity.

The structural unit (I) can be a dicarboxylic acid compound containing a group represented by the above formula (1) or a group represented by the formula (2), as described in detail in the method for synthesizing the [A] polymer described later. It is obtained by polymerization or the like with a diepoxy compound.

The [A] polymer is preferably a polyester (A1) and a polythioester (A2), and more preferably, the structural unit (I) of the polymers has the above formula (3), formula (4) or formula (5) And said.

<[A] Synthesis Method of Polymer>

As a method for synthesizing the [A] polymer, a method for synthesizing the polyester (A1) and the polythioester (A2) will be described in detail below, but the method for synthesizing the [A] polymer in the present invention is not limited to this. Some synthetic methods.

[Synthesis method of polyester (A1)]

The polyester (A1) can be synthesized, for example, by reacting a dicarboxylic acid compound containing a group represented by the above formula (1) with a diepoxy compound in an organic solvent.

A dicarboxylic acid compound containing a group represented by the above formula (1), for example It can be synthesized according to the following procedure.

For example, (E)-cinnamic acid is heated in a solvent such as water/ethanol = 1:1 solution to completely dissolve it, and then cooled and recrystallized, whereby (E)-cinnamic acid can be obtained. Alpha-crystallization. The heating temperature is preferably 70 ° C to 200 ° C, and more preferably 80 ° C to 120 ° C.

The cooling temperature is preferably 20 ° C to 60 ° C, and more preferably 40 ° C to 55 ° C. Then, the α-crystal obtained by recrystallization is pulverized in a mortar or the like until it is in a powder form, and is sandwiched between two Pyrex (registered trademark) glass plates or the like, and is prepared so as to have a uniform thickness. The dicarboxylic acid compound represented by the above formula (B-1) can be synthesized by light irradiation using a 500 W high pressure mercury lamp. The light irradiation time is preferably 2 hours to 10 hours, and more preferably 3 hours to 6 hours.

Examples of the above-mentioned diepoxy compound include the compounds represented by the following formulas. Compounds, etc.

As a diepoxy compound, in the case of using a compound having a 3-membered ring epoxy group (oxirane), The structural unit represented by the above formula (2) and formula (3) can be formed. On the other hand, in the case of using a compound having a 4-membered ring epoxy group (oxetane), the structural unit represented by the above formula (4) can be formed.

In the synthesis of the polyester (A1) used in the present invention, other dicarboxylic acid compounds may be used in combination with the dicarboxylic acid compound containing the group represented by the above formula (1).

Examples of other dicarboxylic acid compounds include isophthalic acid, terephthalic acid, diphenyl ether-4,4'-dicarboxylic acid, and diphenylphosphonium-4,4'-dicarboxylic acid. , benzophenone-4,4'-dicarboxylic acid, 4,4'-diphenyl phthalate, 2,2'-bis(4-carboxyphenyl)hexafluoropropane, 1,3-double ( Carboxyphenyl)-1,1,3,3-tetramethyldioxane, malonic acid, succinic acid, glutaric acid, adipic acid ), pimelic acid, suberic acid, azelaic acid, sebacic acid, malic acid, and the like. These other dicarboxylic acid compounds may be used singly or in combination of two or more.

Ratio of use of the diepoxy compound used in the synthesis reaction of the polyester (A1) to the dicarboxylic acid compound (the total of the dicarboxylic acid compound and the other dicarboxylic acid compound including the group represented by the above formula (1)) The epoxy group of the diepoxy compound is preferably 0.2 equivalents to 2 equivalents, more preferably 0.3 equivalents to 1.2 equivalents, per equivalent of the carboxyl group contained in the dicarboxylic acid compound.

The synthesis reaction is preferably carried out in an organic solvent. The reaction temperature is preferably 0 ° C ~ 250 ° C, more preferably 50 ° C ~ 180 ° C. The reaction time is preferably from 0.5 to 24 hours, more preferably from 2 to 12 hours.

The organic solvent is not particularly limited as long as it is an organic solvent capable of dissolving the synthesized polyester, and examples thereof include N-methyl-2-pyrrolidone (NMP) and N,N-dimethyl group. N,N-dimethylacetamide, N,N-dimethylformamide, N,N-dimethylimidazolidinone, dimethyl Aprotic polar solvents such as dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphonium triamine, m-cresol, xylenol, phenol A phenolic solvent such as a halogenated phenol.

The amount (a) to be used as the organic solvent is preferably 0.1 mass based on the total amount (a+b) of the total amount (b) of the diepoxy compound and the dicarboxylic acid compound and the amount (a) of the organic solvent used. %~50% by mass, more preferably 5% by mass to 30% by mass.

The content ratio of the structural unit (I) represented by the above formula (3) to formula (5) derived from the above dicarboxylic acid compound and the above-mentioned diepoxy compound in the polyester (A1) is relative to all of the polymers. The structural unit is preferably 50 mol% to 100 mol%, more preferably 60 mol% to 100 mol%, still more preferably 80 mol% to 100 mol%.

The polyester (A1) solution obtained after the reaction can be directly used in the preparation of the liquid crystal alignment agent, or the polyester (A1) contained in the reaction solution can be isolated and used for the preparation of the liquid crystal alignment agent, or The isolated polyester is purified and used in the preparation of a liquid crystal alignment agent. Polyester (A1) For example, a method of drying a precipitate obtained by injecting a reaction solution into a large amount of a poor solvent under reduced pressure, and a method of subjecting the reaction solution to distillation under reduced pressure by an evaporator may be mentioned. The method for purifying the polyester is a method in which the isolated polyester (A1) is dissolved again in an organic solvent, and precipitated by a poor solvent; and the step of performing distillation under reduced pressure using an evaporator or the like is performed once. Multiple methods.

In the synthesis of the above polyester (A1), in addition to the above-mentioned diepoxy compound and dicarboxylic acid compound, a terminal-modified polymer can be synthesized by using an appropriate molecular weight modifier. By preparing the terminal-modified polymer, the coating property (printability) of the liquid crystal alignment agent can be further improved without impairing the effects of the present invention.

Examples of the molecular weight modifier include an acid monoanhydride, a monoamine compound, and a monoisocyanate compound.

Examples of the acid monoanhydride include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic anhydride, n-hexadecyl succinic anhydride, and the like.

Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-octylamine.

The monoisocyanate compound may, for example, be phenyl isocyanate or naphthyl isocyanate.

The use ratio of the molecular weight modifier is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, based on 100 parts by mass of the total of the diepoxy compound and the dicarboxylic acid compound to be used.

[Synthesis method of polythioester (A2)]

The polythioester (A2) can be obtained, for example, by reacting a dithio-S-acid compound containing a group represented by the above formula (1) and a diepoxide compound in an organic solvent.

The above-mentioned diepoxy compound is the same as the compound exemplified as the diepoxy compound used for the synthesis of the polyester (A1).

The reaction solution containing the obtained polythioester (A2) can be directly supplied to the preparation of the liquid crystal alignment agent, or can be supplied to the liquid crystal alignment agent after removing the dehydrating agent and the dehydration ring-closing catalyst from the reaction solution, or The polythioester (A2) is isolated and supplied to the preparation of the liquid crystal alignment agent, or the isolated polythioester (A2) may be purified and supplied to the preparation of the liquid crystal alignment agent. These purification operations can be carried out in accordance with a known method.

The polyester (A1) and the polythioester (A2) obtained as described above are preferably 20 mPa when formed into a solution having a concentration of 10% by mass. s~800mPa. The solution viscosity of s, more preferably 30 mPa. s~500mPa. The solution viscosity of s. The solution viscosity (mPa.s) of the above [A] polymer is a concentration of 10% by weight prepared for a good solvent (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.) using the polymer. The polymer solution was measured at 25 ° C using an E-type rotational viscometer.

<Other ingredients>

The liquid crystal alignment agent of the present invention contains [A] polymer as an essential component Points may also contain other ingredients as needed. Examples of the other component include a polymer other than the above [A] polymer, a compound having at least one epoxy group in the molecule (hereinafter also referred to as "epoxy compound"), a functional decane compound, and the like.

(other polymers)

The other polymers described above can be used to improve solution properties and electrical properties.

The other polymer is a polymer other than the polymer [A] such as the polyester (A1) or the above-mentioned polythioester (A2), and examples thereof include a dicarboxylic acid compound having a structure represented by the above formula (1) and a polyester obtained by reacting a diepoxy compound (hereinafter also referred to as "other polyester"), a polythioester having no structure represented by the above formula (1), polyamine, polyoxyalkylene, cellulose derivative , polyacetal, polystyrene derivative, poly(styrene-phenylmaleimide derivative, poly(meth)acrylate, etc. These compounds Other polyesters, other polythioesters are preferred, and other polyesters are more preferred.

The dicarboxylic acid compound for synthesizing the above other polyester or other polythioester may be the same as those described for the other dicarboxylic acid compound for synthesizing the polyester (A1).

The diepoxy compound used for the synthesis of the above other polyester or other polythioester may be exemplified as the exemplified as the diepoxy compound used in the synthesis of the polyester (A1) and the polythioester (A2). Compounds, etc.

The use ratio of the other polymer is preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less based on the [A] polymer.

(epoxy compound)

Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and neopentyl glycol condensed water. Glycerol ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N, N, N', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminemethyl)cyclohexane, N,N,N',N'-tetrahydration Glyceryl-4,4'-diaminodiphenylmethane, N,N-diglycidyl-benzylamine, N,N-diglycidyl-aminomethylcyclohexane, N,N-bi-drink Glyceryl-cyclohexylamine or the like is preferred as the epoxy compound.

The blending ratio of the epoxy compounds is preferably 40 parts by mass or less, and more preferably 0.1 parts by mass to 30 parts by mass, based on 100 parts by mass of the total of the polymer.

(functional decane compound)

Examples of the functional decane compound include 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 2-aminopropyltrimethoxydecane, and 2-aminopropyltriethoxydecane. N-(2-Aminoethyl)-3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, 3-ureidopropyltrimethyl Oxydecane, 3-ureidopropyltriethoxydecane, N-ethoxycarbonyl-3-aminopropyltrimethoxydecane, N-ethoxycarbonyl-3-aminopropyltriethoxydecane , N-triethoxydecylpropyltriethylethylamine, N-trimethoxydecylpropyltriethylamine, 10-trimethoxydecyl-1,4,7- Triazanonane, 10-triethoxydecyl-1,4,7-triazadecane, 9-trimethoxydecyl-3,6-diazaindolyl acetate, 9- Trimethoxydecyl-3,6-diazadecyl acetate, 9-triethoxydecyl-3,6-diazadecyl acetate, 9-trimethoxydecyl-3 , methyl 6-diazepine, methyl 9-triethoxydecyl-3,6-diazepine, N-benzyl-3-aminopropyltrimethoxydecane, N-benzyl 3-aminopropyltriethoxydecane, N-phenyl-3-aminopropyltrimethoxydecane, N-phenyl-3-aminopropyltriethoxydecane, glycidoxymethyl Trimethoxy decane, glycidoxymethyl triethoxy decane, 2-glycidoxyethyl trimethoxy decane, 2-glycidoxyethyl triethoxy decane, 3-glycidoxy Propyltrimethoxydecane, 3-glycidoxypropyltriethoxydecane, and the like.

The blending ratio of the functional decane compound is preferably 2 parts by mass or less, and more preferably 0.02 parts by mass to 0.2 parts by mass, based on 100 parts by mass of the total of the polymer.

<Modulation of liquid crystal alignment agent>

The liquid crystal alignment agent of the present invention is preferably composed of the above-mentioned polyester (A1), polythioester (A2) or the like [A] polymer, and other components optionally arbitrarily formulated and dissolved in an organic solvent.

Examples of the organic solvent used in the liquid crystal alignment agent of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butylide, N,N-dimethylformamide, and N. N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethoxypropyl Ethyl acetate, ethylene glycol methyl ether, ethylene glycol ether, Ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol Alcohol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate , isoamyl isobutyrate, diisoamyl ether, ethylene carbonate, propylene carbonate and the like. These organic solvents may be used singly or in combination of two or more.

The solid content concentration in the liquid crystal alignment agent of the present invention (the ratio of the total mass of the components other than the solvent in the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) can be appropriately selected in consideration of viscosity, volatility, and the like, and is preferably selected. It is in the range of 1% by mass to 10% by mass. In other words, the liquid crystal alignment agent of the present invention can be applied to the surface of the substrate as described later, and is preferably heated to form a coating film as a liquid crystal alignment film or a coating film to be a liquid crystal alignment film, but the solid content is less than 1 mass. In the case of %, the film thickness of the coating film is too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content exceeds 10% by mass, the film thickness of the coating film becomes too large to obtain a good liquid crystal alignment. Further, the film and the viscosity of the liquid crystal alignment agent are increased to cause deterioration in coating properties.

A particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal alignment agent is applied onto the substrate. For example, in the case of using the spin coating method, the solid content concentration is particularly preferably in the range of 1.5% by mass to 4.5% by mass. In the case of using the printing method, it is particularly preferable to set the solid content to a range of 3% by mass to 9% by mass, thereby making the solution viscosity 12 mPa. s~50mPa. The scope of s. In the case of using the inkjet method In particular, it is particularly preferable to set the solid content to a range of 1% by mass to 5% by mass, thereby making the solution viscosity 3mPa. s~15mPa. The scope of s.

The temperature at which the liquid crystal alignment agent of the present invention is prepared is preferably 10 ° C to 50 ° C, and more preferably 20 ° C to 30 ° C.

<Liquid alignment film>

The liquid crystal alignment film of the present invention can be formed by the liquid crystal alignment agent. Therefore, it is possible to impart excellent liquid crystal alignment energy by using radiation of a low irradiation amount in the formation step. Further, since the irradiation step of the radiation and the heating step after the irradiation are not required, the production efficiency is good and the manufacturing cost can be reduced.

<Method of Forming Liquid Crystal Alignment Film>

The liquid crystal alignment agent of the present invention can be suitably used as a liquid crystal alignment film material of a photo-alignment method. Further, it can be suitably used to form a liquid crystal display element having a TN type or STN type liquid crystal cell, or a liquid crystal alignment film used in a lateral electric field type liquid crystal display element having a liquid crystal cell such as an IPS type or an FFS type. In particular, when the liquid crystal alignment agent of the present invention is applied to a liquid crystal display device having an IPS type or FFS type liquid crystal cell, the effect of the present invention is maximized, and it is preferably used.

The method for forming a liquid crystal alignment film of the present invention comprises the following steps:

(1) a step of forming a coating film on a substrate by using the liquid crystal alignment agent of the present invention (hereinafter also referred to as "step (1)"), and (2) irradiating the coating film with polarized ultraviolet rays to impart alignment energy to the liquid crystal The steps (hereinafter also referred to as "step (2)"). Hereinafter, each step will be described in detail.

[step 1)]

Here, when the liquid crystal alignment agent of the present invention is applied to a liquid crystal display device having a TN type or STN type liquid crystal cell, two substrates each having a patterned transparent conductive film are provided as a pair. The liquid crystal alignment agent of the present invention is applied onto the transparent conductive film forming surface to form a coating film. On the other hand, when the liquid crystal alignment agent of the present invention is applied to a liquid crystal display device having an IPS type or FFS type liquid crystal cell, a transparent conductive film or a metal film is patterned on one surface into a comb shape. The substrate of the electrode and the counter substrate not provided with the electrode are paired, and the liquid crystal alignment agent of the present invention is applied to each of the forming surface of the comb-shaped electrode and the single surface of the counter substrate to form a coating film.

In any case, the substrate may be, for example, a glass such as float glass or soda glass, such as polyethylene terephthalate, polybutylene terephthalate, polyether oxime or polycarbonate. Plastic transparent substrate, etc. As the transparent conductive film, for example, an ITO film containing In ₂ O ₃ —SnO ₂ , a NESA (registered trademark) film containing SnO ₂ , or the like can be used. As the metal film, for example, a film containing a metal such as chromium can be used. In the patterning of the transparent conductive film and the metal film, for example, a method of forming a pattern by a photolithography method, a sputtering method, or the like after forming a transparent conductive film having no pattern can be used, and a method for forming a transparent conductive film can be used. A method of masking a desired pattern, and the like.

When the liquid crystal alignment agent is applied onto the substrate, in order to further improve the adhesion between the substrate or the conductive film or the electrode and the coating film, a functional decane compound, titanate or the like may be applied to the substrate and the electrode in advance.

Coating the liquid crystal alignment agent on the substrate can preferably use offset printing By a suitable coating method such as a method, a spin coating method, a roll coating method, or an inkjet printing method, second, the coated surface is preheated (prebaked), and then calcined (post-baked) to form a coating film. . The prebaking conditions are, for example, from 40 ° C to 120 ° C for 0.1 minutes to 5 minutes, and the post-baking conditions are preferably from 120 ° C to 300 ° C, more preferably from 150 ° C to 250 ° C, preferably from 5 minutes to 200 minutes. More preferably, it is 10 minutes - 100 minutes. The film thickness of the coating film after post-baking is preferably 0.001 μm to 1 μm, and more preferably 0.005 μm to 0.5 μm.

[Step (2)]

The coating film formed in this manner is irradiated with the polarized radiation to impart liquid crystal alignment energy. Here, as the radiation, for example, ultraviolet rays and visible rays containing light having a wavelength of 150 nm to 800 nm can be used, and ultraviolet rays containing light having a wavelength of 200 nm to 400 nm are preferable.

As the light source to be used, for example, a low pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, a metal halide lamp, a hydrogen resonance lamp, a xenon lamp, an excimer laser or the like can be used. The ultraviolet light in the above preferred wavelength region can be obtained by a method in which the above-mentioned light source is used in combination with, for example, a filter, a diffraction grating, or the like.

When the liquid crystal alignment agent of the present invention is used, when it is necessary to irradiate ultraviolet rays of 10,000 J/m ² or more, it is possible to impart good liquid crystal alignment energy even at 8000 J/m ² , which contributes to productivity of the liquid crystal display element. Increase and cut manufacturing costs.

<Liquid crystal display element>

The liquid crystal display element of the present invention contains a liquid crystal alignment film formed using the liquid crystal alignment agent, and thus can be irradiated with less radiation than before. The amount of radiation gives the liquid crystal alignment energy. Therefore, the liquid crystal display element including the liquid crystal alignment film can be manufactured at a lower cost than before. The liquid crystal display element of the present invention can be produced, for example, in the following manner.

A pair of substrates on which a liquid crystal alignment film is formed as described above is prepared, and a liquid crystal cell having a liquid crystal structure between the pair of substrates is manufactured. The following two methods are exemplified for the production of the liquid crystal cell.

The first method is a method known from the previous one. The liquid crystal alignment film is opposed to each other so that the two substrates are opposed to each other with a gap (cell gap) therebetween, and the peripheral portions of the two substrates are bonded together using a sealant, and the cells are divided by the substrate surface and the sealant. After the filling liquid crystal is injected into the gap, the injection hole is sealed, whereby the liquid crystal cell can be manufactured.

The second method is called the One Drop Fill (ODF) method. For example, an ultraviolet curable sealing material is applied to a predetermined position on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystal is further dropped on the liquid crystal alignment film surface, and then the liquid crystal alignment film is opposed to each other. The other substrate is bonded, and the entire surface of the substrate is irradiated with ultraviolet light to harden the sealing agent, whereby the liquid crystal cell can be manufactured.

In the case of using any method, it is preferred to further heat the liquid crystal cell to a temperature at which the liquid crystal used becomes an isotropic phase, and then gradually cool to room temperature, thereby removing the flow alignment at the time of liquid crystal filling.

Next, the liquid crystal display element of the present invention can be obtained by laminating a polarizing plate on the outer surface of the liquid crystal cell. Here, the linear polarized light irradiated on the two substrates on which the liquid crystal alignment film is formed can be appropriately adjusted. The angle formed by the polarization direction of the ray and the angle of each substrate and the polarizing plate are used to obtain a desired liquid crystal display element.

As the sealing agent, for example, an alumina ball as a spacer, an epoxy resin containing a curing agent, or the like can be used.

For the liquid crystal, for example, a nematic liquid crystal, a smectic liquid crystal, or the like can be used. It is preferable to form a liquid crystal having a positive dielectric anisotropy of a nematic liquid crystal, for example, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, a terphenyl liquid crystal, or a biphenyl ring. A hexane liquid crystal, a pyrimidine liquid crystal, a dioxane liquid crystal, a bicyclooctane liquid crystal, a cubic liquid crystal, or the like. Further, for example, a cholesteric liquid crystal such as cholesteryl alcohol, cholesteryl phthalate or cholesteryl carbonate may be further added to the liquid crystal; for example, trade names "C-15" and "CB-15" (available from Merck) commercially available chiral agent; p-decyloxy-benzyl-2-methylbutyl cinnamate (p-decyloxy benzylidene-p-amino-2-) Methyl butyl cinnamate and other ferroelectric liquid crystals.

The polarizing plate used for the outer side of the liquid crystal cell may be a polarizing film called "H film" sandwiched between a cellulose acetate protective film (the H film is formed by absorbing iodine on one side of the polyvinyl alcohol. A polarizing film made of a polarizing film or a polarizing plate including the H film itself. The liquid crystal display element of the present invention produced as described above is excellent in display characteristics and electrical characteristics.

<polymer>

The polymer contained in the liquid crystal alignment agent of the present invention has a structural unit (I) containing a group represented by the above formula (1) or formula (2). The polymer is preferably a polyester or a polythioester, and the structural unit (I) is more preferably a structural unit represented by the above formula (3), formula (4) or formula (5), and still more preferably the above formula (3). ) the structural unit represented. Since the polymer of the present invention has the above specific structure, it is suitably used as the [A] polymer in the liquid crystal alignment agent, and the liquid crystal alignment agent containing the polymer of the present invention has high sensitivity to radiation and can be used with low irradiation. The amount of radiation forms a liquid crystal alignment film having excellent liquid crystal alignment energy. Further, the description of the [A] polymer contained in the liquid crystal alignment agent can be applied to the polymer of the present invention, and thus the detailed description herein will be omitted.

[Example]

Hereinafter, the present invention will be more specifically illustrated by the examples, but the present invention is not limited by the examples.

<Synthesis of Dicarboxylic Acid>

The compound represented by the following formula (B-1) was synthesized according to the following scheme.

[Chemical 6]

[Synthesis Example 1]

2.00 g of (E)-cinnamic acid was added to 10 mL of a water/ethanol = 1/1 solution, and heated to 90 ° C in an oil bath to completely dissolve. The oil bath was set to 50 ° C, and crystallization was gradually carried out to obtain 1.3 g (yield of 65%) of α-crystal of (E)-cinnamic acid. 150 mg of the α-crystal obtained by recrystallization was pulverized in a mortar until it was in a powder form, and it was prepared by sandwiching two Pyrex (registered trademark) glass plates to have a uniform thickness. Light irradiation was performed for 4 hours using a 500 W high pressure mercury lamp, and 147 mg of the compound (B-1) represented by the above formula (B-1) was obtained. Further, the synthesis is repeated over the above-described scale, thereby ensuring the necessary amount in the subsequent synthesis example of the polyester.

<Synthesis of Polyester (A1)>

The diepoxy compounds used in the synthesis of the polyester are as follows.

[Chemistry 7]

[Example 1]

0.1 mol (29.62 g) of the compound (B-1) and 0.1 mol (17.72 g) of the diepoxy compound (E-1) represented by the above formula (E-1) were dissolved in N-methyl-2- In 110.46 g of pyrrolidone, the reaction was carried out at 140 ° C for 9 hours. Next, the reaction mixture was mixed with a large excess of methanol to precipitate a reaction product. Then, it was washed with methanol, and dried under reduced pressure at 40 ° C for 15 hours to obtain 45.9 g of a polyester (A-1) (yield: 97.0%).

[Example 2]

A polyester (A-2) was obtained in the same manner as in Example 1 except that the compound (E-2) represented by the above formula (E-2) was used.

[Comparative Synthesis Example 1]

0.1 mol (1. 156 g) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 0.1 mol (41.05 g) of the following diamine compound (D-1) were dissolved in N-methyl-2- The reaction was carried out for 6 hours at room temperature in 343.74 g of pyrrolidone. Second, the reaction mixture is mixed with a large excess of methanol to make The reaction product precipitated. Thereafter, the mixture was washed with methanol, and dried under reduced pressure at 40 ° C for 15 hours to obtain 60 g of polylysine (a-1) (yield 98.9%).

[Comparative Synthesis Example 2 to Comparative Synthesis Example 3]

In the same manner as in Comparative Synthesis Example 1, except that the diamine compound was used as the following (D-2) or (D-3), respectively, polyphosphoric acid (a-2) and polylysine were obtained. A-3).

[diamine compound]

D-1: 2,2-bis[4-(4-aminophenoxy)phenyl]propane

D-2: p-phenylenediamine

D-3: 4,4'-diaminodiphenyl ether

<Modulation of liquid crystal alignment agent> [Example 3]

N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) were added to the solution containing the polyester (A-1) obtained in the above Synthesis Example 1, relative to poly-proline (A1-1) 100 parts by mass in total, and further adding 20 parts by mass of N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane as an epoxy compound, and sufficiently stirred to prepare a solvent The composition was a solution of NMP: BC = 60: 40 (mass ratio) and a solid concentration of 2.5% by mass. This solution was filtered using a screening procedure having a pore size of 1 μm to prepare a liquid crystal alignment agent (S-1).

[Example 4 and Comparative Example 1 to Comparative Example 3]

In Example 3, polyester (A-2) and polylysine (a-1)-polyproline (a-3) were used instead of polyester (A-1), respectively, and Example 3 was used. The liquid crystal alignment agent S-2, the liquid crystal alignment agent s-1 to the liquid crystal alignment agent s-3 were prepared in the same manner.

<Manufacture of liquid crystal display element>

The liquid crystal alignment agents (S-1 to S-2 and s-1 to s-3) prepared as described above were applied to a transparent electrode containing an ITO film so as to have a film thickness of 0.1 μm using a rotator. The transparent electrode surface of the glass substrate was dried at 200 ° C for 1 hour to form a coating film. Using a Hg-Xe lamp, the surface of the coating film was irradiated with a polarized ultraviolet ray of 8,000 J/m ² , 10,000 J/m ² or 50,000 J/m ^{2 of} a bright line of 254 μm from the normal direction of the substrate to form a liquid crystal alignment film. Next, for the pair of substrates subjected to the above-described light irradiation treatment, an epoxy resin having a diameter of 5.5 μm was placed on the edge of the surface on which the liquid crystal alignment film was formed, leaving a liquid crystal injection port and screen-printing and applying an alumina ball having a diameter of 5.5 μm. Next, the substrate was laminated so that the light irradiation direction became antiparallel, and the pressure was bonded, and the adhesive was thermally cured at 150 ° C for 1 hour. Next, a nematic liquid crystal (manufactured by Merck & Co., Ltd., ZLI-1565) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy-based adhesive. Further, it was heated at 150 ° C and then slowly cooled to room temperature to remove the flow alignment at the time of liquid crystal injection. Next, two of the outer sides of the substrate are arranged such that the polarization directions of the polarizing plates are orthogonal to each other, and one of the optical axes of the polarized ultraviolet rays of the liquid crystal alignment film on the substrate surface is orthogonal to each other and the other is parallelized. The polarizing plate is attached to the surface to fabricate a liquid crystal display element.

Each of the above liquid crystal display elements was subjected to the following evaluation. The results are shown in Table 1.

<evaluation> [Liquid alignment]

The presence or absence of an abnormal region when the voltage is turned on/off (applied/released) in the liquid crystal display device is observed with a polarizing microscope, and the case where the abnormal region is not present is judged as "good", and even if there is one abnormal region, it is determined as "bad".

[Voltage retention rate]

A liquid crystal display element produced by irradiating a polarized ultraviolet ray of 8,000 J/m ² was applied with a voltage of 5 V after application of 60 microseconds and a span of 167 milliseconds, and then the voltage retention rate after 167 milliseconds of application was released. . The measuring device used VHR-1 manufactured by Dongyang Technology Co., Ltd. The case where the voltage holding ratio was 90% or more was judged as "good", and the other cases were judged as "bad".

As shown in Table 1, the liquid crystal alignment agent of the example has high sensitivity to radiation, and even at a low irradiation amount of 8,000 J/m ² , the liquid crystal alignment property of the liquid crystal display element including the obtained liquid crystal alignment film is also improved. Moreover, the voltage holding ratio is also good. In comparison with this, in the comparative example, an abnormal region was observed at a low irradiation amount of 8,000 J/m ² , and liquid crystal alignment became poor. According to the above, the liquid crystal alignment agent of the present invention is excellent in radiation sensitivity, and can form a liquid crystal alignment film having excellent liquid crystal alignment properties by irradiation with a low irradiation amount.

[Industrial availability]

Since the liquid crystal alignment agent of the present invention has high radiation sensitivity and can form a liquid crystal alignment film having excellent liquid crystal alignment properties by irradiation with a low irradiation amount, the production efficiency is good, and the production cost can be reduced. In addition, the liquid crystal display element including the liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention is also excellent in electrical characteristics and the like. Therefore, the liquid crystal alignment agent, the liquid crystal alignment film, the method of forming the liquid crystal alignment film, and the liquid crystal display element of the present invention can be suitably used for liquid crystal display elements such as IPS type and FFS type.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

Claims (6)

A liquid crystal alignment agent comprising: [A] a polymer having a structural unit (I) represented by the following formula (3), formula (4) or formula (5) in a main chain; In the formulae (3) to (5), R ¹ and R ² each independently represent a hydrogen atom or a monovalent organic group; X is an oxygen atom or a sulfur atom; and Y ¹ to Y ³ are each independently a divalent organic group. The liquid crystal alignment agent according to claim 1, which is Light alignment. A method for forming a liquid crystal alignment film, comprising: (1) a step of forming a coating film on a substrate using a liquid crystal alignment agent according to claim 2; and (2) irradiating the coating film with a polarized light Ultraviolet rays, a step of imparting alignment ability to a liquid crystal. A liquid crystal alignment film formed by using a liquid crystal alignment agent as described in claim 1 or 2. A liquid crystal display element having the liquid crystal alignment film according to item 4 of the patent application. a polymer having a structural unit represented by the following formula (3) in a main chain; In the formula (3), R ¹ and R ² each independently represent a hydrogen atom or a monovalent organic group; X is an oxygen atom or a sulfur atom; and Y ¹ is a divalent organic group.