JP2003270638A - Composition for photo-alignment layer, and method for manufacturing photo-alignment layer using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo-alignment layer by which satisfactory alignment characteristics such as a large pretilt angle and a high order parameter can be obtained and whose alignment properties are not changed and stability is excellent even when the photo-alignment layer is exposed to external light and is preserved for a long period of time. <P>SOLUTION: The composition for the photo-alignment layer containing a radically polymerizable monomer having dichroic molecules and a mesogen group and a method for manufacturing the photo-alignment layer, characterized in that the composition for the photo-alignment layer is applied on a substrate, irradiated with linearly polarized light or non-polarized light from an oblique direction, both having a wavelength to be absorbed by the dichroic molecules, and then heat- or photo-cured, are provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment film used in a liquid crystal display device, and more particularly to a photo-alignment film capable of aligning liquid crystals without rubbing.

[0002]

2. Description of the Related Art In recent years, as a liquid crystal alignment film used for a liquid crystal display device, an alignment film capable of aligning liquid crystals without rubbing has been attracting attention in place of a conventional polyimide alignment film formed by a rubbing method. The method of forming such a rubbingless alignment film is an oblique vapor deposition method, an LB (Langmuir-Blodgett) film method, a photolithography method,
Photo-alignment methods are being studied, but among them, photo-alignment methods that irradiate a coating film on a substrate with polarized light to cause liquid crystal alignment ability in the coating film are easy to manufacture and are actively studied. Is being done. This photo-alignment method utilizes a photo-reaction of a compound having a group that exhibits a photo-alignment function, for example, a photoisomerization reaction of an azobenzene derivative, a photodimerization reaction of a cinnamic acid derivative, a coumarin derivative, and a chalcone derivative. , A photo-crosslinking reaction of a benzophenone derivative, a photo-decomposition reaction of a polyimide resin, and the like have been reported.

As a raw material for an alignment film (hereinafter referred to as a photo-alignment film) formed by a photo-alignment method, a main chain or a side chain is provided so that a uniform film can be obtained when applied to a substrate such as glass. A polymer material into which a group that exhibits the photo-alignment function is introduced is often used. Further, a compound having a group that exhibits a photo-alignment function may be used as a guest compound and dispersed in a polymer resin or the like as a host compound. For example,
U.S. Pat. No. 4,974,941 discloses a photo-alignment film material in which dichroic molecules are mixed with a resin such as polyimide. However, since the orientation state of the dichroic molecules in the obtained photo-alignment film is not fixed, the orientation may change gradually due to external factors such as light irradiation and heat. Therefore, it is not practical because it cannot withstand use in an environment exposed to external light and long-term storage.

On the other hand, in Japanese Patent Application Laid-Open No. 8-328005 and US Pat. No. 6,001,277, a film of a resin containing a structural unit capable of photoisomerization and exhibiting dichroism, and an acryloyl group is disclosed. Disclosed is a liquid crystal alignment film obtained by irradiating polarized light with a liquid crystal alignment ability and having a fixed liquid crystal alignment ability. However, this has a problem in that a large pretilt angle or order parameter cannot be obtained because the constitutional unit having dichroism is a high molecular weight substance chemically bonded to the resin.

[0005]

The problem to be solved by the present invention is that good alignment characteristics such as a large pretilt angle and order parameter can be obtained, and the alignment property does not change even when exposed to external light or long-term storage. It is to provide a photo-alignment film having excellent properties.

[0006]

That is, in order to solve the above-mentioned problems, the present invention comprises a composition for a photo-alignment film containing a dichroic molecule and a radical-polymerizable monomer having a mesogenic group. Provide things.

In order to solve the above problems, the present invention applies a composition for a photo-alignment film containing a dichroic molecule and a radically polymerizable monomer having a mesogenic group onto a substrate to form a dichroic film. By photo-aligning the dichroic molecule and the radical-polymerizable monomer having a mesogenic group by irradiating linearly polarized light having a wavelength absorbed by the molecule or unpolarized light from an oblique direction, by heating or irradiating light Provided is a method for producing a photo-alignment film, which comprises polymerizing the radical-polymerizable monomer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The composition for a photo-alignment film of the present invention contains a dichroic molecule and a radical-polymerizable monomer having a mesogenic group. The dichroic molecule is a molecule having a chromophore and having a property that light absorption by the chromophore differs depending on the polarization direction of incident linearly polarized light. As the chromophore of the dichroic molecule used for the photo-alignment of the present invention, those having absorption in the ultraviolet region or the visible region are preferable. When a dichroic molecule is irradiated with linearly polarized light, it absorbs polarized light having an electric vector that coincides with the direction of the electronic transition moment of this molecule, and rearranges, that is, photo-aligns in a direction orthogonal to this.

As the dichroic molecule used in the present invention, for example, the compounds disclosed in JP-A No. 05-241151 can be used. As a concrete example,
Azobenzene, azonaphthalene, azo compounds having an aromatic heterocycle, bisazo compounds, formazan, azoxybenzene, anthraquinone, quinophthalone, perylene, polyene, aromatic Schiff base, aromatic hydrazone, stilbazole, stilbene, cinnamic acid, hemithioindigo, etc. Can be mentioned. Among them, azobenzene is particularly preferable because it shows a good photo-alignment property.

In the radical polymerizable monomer having a mesogen group used in the present invention (hereinafter, the polymerizable monomer used in the present invention is abbreviated), the mesogen group means a mesogen group usually used in the technical field of liquid crystals. A group which is recognized as, and which is generally a rod-like liquid crystal compound, has linearity and rigidity, and is composed of two or more rings and a single bond or a linking group connecting the rings. Indicates. The ring that the mesogen group has is not particularly limited, and examples thereof include an alicyclic hydrocarbon ring, an aromatic ring, and a heterocycle. These may be a condensed ring or may have a substituent. Of these, aromatic rings are preferred. Examples of the alicyclic hydrocarbon ring include a cyclopropane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring and the like. A benzene ring is mentioned as an aromatic ring. As the heterocycle, an oxirane ring, a pyridine ring, a pyrimidine ring,
Examples thereof include piperazine ring and furan ring. Moreover, a naphthalene ring is mentioned as a condensed ring.

The number of rings in the mesogen group is not particularly limited as long as it is 2 or more, but 2 to 30 is preferable, and 2 to 2 is preferable.
0 is more preferable and 2 to 12 is particularly preferable. The linking group for linking the rings is, for example, -O.
-, - S -, - CO -O -, - OCO -, - CH 2 CH
_2- , -CH = CH-, -CH≡CH-, -OCH
_2- , -CO-N (R)-, -N (R) -CO-, -C
_{H 2 O -, - CH =} CH-CO-O -, - OCO-CH
= CH-, a single bond, and the like. (R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

Examples of the radically polymerizable group contained in the polymerizable monomer used in the present invention include an acryloyloxy group, a methacryloyloxy group, an acrylamide group, a methacrylamide group, a vinyl group, an allyl group, an isopropenyl group and a maleimide. Group, nadiimide group and the like. Among them, the maleimide group is particularly preferable because it can perform a polymerization reaction without using a photopolymerization initiator or a thermal polymerization initiator and in the presence of oxygen.

The mesogenic group and the radically polymerizable group may be directly bonded or may be bonded via a spacer between them. The spacer is not particularly limited, but for example, a spacer composed of a methylene chain having 2 to 20 carbon atoms is preferable.

When the mesogenic group and the radically polymerizable group contained in the polymerizable monomer used in the present invention are bonded so that the molecular structure of the polymerizable monomer is linear, liquid crystallinity is exhibited. Is preferred, which is preferable. For example, it is preferable that the mesogen group has a 6-membered ring such as a benzene ring or a cyclohexane ring at both ends, and a radically polymerizable group is bonded to the 4-position of the 6-membered ring directly or via a spacer. . The radically polymerizable monomer having a mesogen group does not necessarily have to show a liquid crystal phase at room temperature, but a compound showing a nematic liquid crystal phase or a smectic liquid crystal phase at room temperature is more preferable.

The polymerizable monomer used in the present invention is irradiated with polarized light to be photo-aligned, and then the radical-polymerizable group is polymerized by heating or light irradiation in the aligned state. Thereby, the alignment state can be fixed. In order to maintain this alignment state more stably, the polymer preferably has a network structure. Therefore, the polymerizable monomer preferably has two or more radically polymerizable groups.

Preferred examples of the polymerizable monomer used in the present invention include compounds represented by the general formula (1) as shown in JP-A-2000-191640.

[0017]

[Chemical 1] General formula (1)

In the formula, each A independently has 3 to 2 carbon atoms.
Represents a polymethylene chain of 0, X is independently -CO
-O -, - CONH-, or -O- and represents, M is a single _{bond, -CH 2 -CH 2 -, -} CH = CH -, - C≡C
-, - CO-O -, - CONH -, - C (CH 3) = C
H-, -CH = N-, -CH = NN-CH =, or-
N = N-represents a mesogenic group consisting of at least two rings bonded to each other, and R's each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a phenyl ring or a halogen atom.

The dichroic molecule and the polymerizable monomer are 1
You may use it for each kind or to mix several kinds respectively. The dichroic molecule is contained in the composition for alignment film in an amount of 20.
It is preferable to use -80% by mass because good orientation can be obtained. Above all, 40 to 70 mass% is more preferable.
On the other hand, when the polymerizable monomer is used in an amount of 20 to 80 mass% with respect to the total amount of the composition for an alignment film, the alignment property can be more stabilized, which is preferable.

Next, an example of a method for producing a photo-alignment film and a liquid crystal display device having the photo-alignment film using the composition for a photo-alignment film of the present invention will be described. First, the composition for a photo-alignment film of the present invention is used by dissolving it in a suitable solvent. At this time, the solvent is not particularly limited, but N-methylpyrrolidone, N, N-dimethylformamide, butyl cellosolve, γ-butyrolactone, chlorobenzene, dimethyl sulfoxide, dimethylacetamide, tetrahydrofuran and the like are generally used. Among them, butyl cellosolve, γ-butyrolactone,
A solution of N-methylpyrrolidone or N, N-dimethylformamide is particularly preferable because it has good coatability on a glass substrate or the like and a uniform film can be obtained. These solvents are
Two or more kinds may be mixed and used in consideration of the coating property and the volatilization rate of the solvent after coating.

The substrate used in the present invention is a substrate usually used for a liquid crystal display device having an alignment film, and preferably has a heat resistance capable of withstanding heating during the production of the liquid crystal display device. Examples of such a substrate include a glass substrate.
A solution of the composition for a photo-alignment film is applied onto a substrate by a method such as a spin coating method and a printing method, and after drying, a photo-alignment operation of a coating film comprising the composition for a photo-alignment film and immobilization of the alignment by polymerization. Do for.

The photo-alignment of the coating film obtained by coating and drying the composition for a photo-alignment film of the present invention is performed by irradiating the coating film with polarized light or non-polarized light obliquely to the film surface. The polarized light may be linearly polarized light or elliptically polarized light. The light used is light having a wavelength range in which the dichroic molecule has absorption, and specific examples thereof include visible light and ultraviolet light. Ultraviolet rays having a wavelength in the range of 300 to 400 nm are particularly preferable. Actually, linearly polarized ultraviolet light can be obtained by passing light from an ultraviolet light source such as a xenon lamp, a high-pressure mercury lamp, or a metal halide lamp through a polarizing filter or a polarizing prism such as Glan-Thompson or Glan-Taylor. Further, it is particularly preferable that the light is parallel light regardless of whether polarized light or non-polarized light is used. This photo-alignment operation is usually performed in air. In particular, when the radically polymerizable group in the coating film is a group that is susceptible to polymerization inhibition by oxygen such as an acryloyloxy group, the oxygen in the air inhibits the polymerization of the acryloyloxy group, and the photoalignment of dichroic molecules is Since it proceeds preferentially, the photo-alignment operation can be performed efficiently.

After photo-aligning the coating film comprising the composition for photo-alignment film, the radical-polymerizable monomer having a mesogenic group in the coating film is polymerized and fixed. Examples of the polymerization method include heating and irradiation with light such as ultraviolet rays. At this time, a polymerization initiator is usually added to the composition for photo-alignment film. As the polymerization initiator, known ones can be used, for example, thermal polymerization of benzoyl peroxide, 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, azobisisobutyronitrile, etc. Initiator, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-
Examples include photopolymerization initiators such as 1 [(methylthio) phenyl] -2-morpholinopropane-1, benzyldimethylketal, and acylphosphine oxide. On the other hand, when the radical-polymerizable group of the radical-polymerizable monomer is a maleimide group, the radical-polymerizable monomer can be immobilized without using the polymerization initiator.

As the polymerization method, thermal polymerization is convenient and
preferable. The heating temperature is preferably 100 to 300 ° C, more preferably 100 to 200 ° C. Within this range, polymerization can be carried out without affecting the oriented dichroic molecule. In this case, it is more preferable to use a radical-polymerizable monomer having a maleimide group as a radical-polymerizable group, because curing can be performed without using a thermal polymerization initiator. As the polymerization method, it is possible to use irradiation with light such as ultraviolet rays, but when the radically polymerizable group in the coating film is a group that is susceptible to polymerization inhibition by oxygen such as acryloyloxy group, it cannot be completely polymerized in air. Therefore, it is necessary to polymerize in a nitrogen atmosphere. On the other hand, when the radically polymerizable group in the coating film is a maleimide group that is less susceptible to oxygen inhibition, it can be polymerized in the same air atmosphere as the photo-alignment operation, but with the light to be irradiated,
If the dichroic molecules that have already been aligned absorb, the alignment may be disturbed. Therefore, at this time, the wavelength of the irradiation light may be set to a wavelength that is absorbed only by the maleimide group and not by the dichroic molecule, for example, 313 nm. The light irradiation irradiates the coating film surface with, for example, non-polarized light from the vertical direction.

When the composition for a photo-alignment film of the present invention is irradiated with linearly polarized light, the dichroic molecules are arranged in a direction such that the polarization direction and the direction of the electronic transition moment of the dichroic molecule are orthogonal to each other. Since the arranged dichroic molecules have a function of orienting the radical-polymerizable monomer having a mesogenic group, the radical-polymerizable monomer having a mesogenic group is also oriented according to the arrangement of the dichroic molecules. By heating or irradiating light in this state to polymerize the radical-polymerizable monomer, the orientation state of the radical-polymerizable monomer having a dichroic molecule and a mesogenic group can be fixed.

By using the composition for a photo-alignment film of the present invention, an alignment film having a high liquid crystal alignment ability, for example, an order parameter and a large pretilt angle of liquid crystal molecules can be obtained. Further, since the oriented dichroic molecule is fixed by the copolymer obtained by orienting and polymerizing the radical-polymerizable monomer, it is possible to obtain an oriented film stable to heat and light.

Next, an example of a method for producing a liquid crystal display device using the photo-alignment film produced by the method for producing a photo-alignment film of the present invention will be described below. That is, the solution of the composition for a photo-alignment film of the present invention is applied to the electrode-side surfaces of two glass substrates provided with transparent electrodes such as ITO, and after drying, a photo-alignment operation and a polymerization operation are performed. Thus, a photo-alignment film is produced.
Next, the surface provided with this photo-alignment film, through a spacer,
For example, in the case of a twisted nematic cell, they are opposed to each other so that their photo-alignment directions are orthogonal to each other, and liquid crystal is injected into the gap. A liquid crystal display device can be manufactured by sticking a polarizing plate on the outside of the liquid crystal cell thus manufactured so that the alignment direction of the photo-alignment film on each substrate and the transmitted polarization direction are the same. .

[0028]

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

[Synthesis Example of Radical Polymerizable Monomer Having Two Maleimide Groups at Both Ends of Mesogen Group] In a 300 ml three-necked flask equipped with a thermometer and a dropping funnel, 29.0 g of 4-iodophenol was added. , Paratoluenesulfonic acid 9
Then, 50 mg of dichloromethane and 50 ml of dichloromethane were added and suspended in an ice-cooled bath with stirring. 22.2 g of 3,4-dihydropyran
Was dissolved in 220 ml of dichloromethane and added dropwise over about 1 hour while maintaining the temperature at 10 ° C or lower. After completion of dropping, the mixture was stirred at room temperature under a nitrogen atmosphere for about 4 hours. When a dark brown homogeneous solution was obtained, it was confirmed by thin layer chromatography that no raw material remained, and then the reaction was terminated. The reaction solution was washed with a saturated aqueous solution of sodium hydrogen carbonate and then with a saturated saline solution, and finally dried over anhydrous potassium carbonate. After the potassium carbonate was filtered off, the solvent was removed to give the crude product 4.
7.2 g was obtained. The obtained crude product was purified by column chromatography (developing layer: silica gel 250 g, developing solvent: hexane / dichloromethane = 2/1 mixed solution) to obtain a compound represented by the chemical formula (2).

[0030]

[Chemical 2] Chemical formula (2)

A 1-liter three-necked flask equipped with a thermometer and a nitrogen inlet tube was charged with 60 g of the compound of the chemical formula (2), 23.3 g of trimethylsilylacetylene, 240 g of dimethylformamide, and 70 g of trimethylamine to obtain a uniform solution. While cooling this with water, under nitrogen atmosphere, 2.74 g of triphenylphosphine palladium as a catalyst,
0.75 g of copper iodide was added. After stirring for 3 hours, it was confirmed by gas chromatography that no raw material remained, and the reaction was terminated. The reaction solution was washed with 1 liter of ethyl acetate and then 500 ml of saturated saline. Finally it was dried over potassium carbonate. After the potassium carbonate was filtered off, the solvent was removed to obtain a crude product represented by the chemical formula (3). Yield: 6.1g

[0032]

[Chemical 3] Chemical formula (3)

3 equipped with nitrogen inlet tube, thermometer, dropping funnel
To a 00 ml four-necked flask, 46 g of tetrabutylammonium fluoride and 65 g of dichloromethane were placed to prepare a uniform solution. While keeping this at 10 ° C. or lower in an ice-cooled bath, a solution prepared by dissolving 39 g of the compound of the chemical formula (3) in 100 ml of dichloromethane was added dropwise over 30 minutes under a nitrogen atmosphere. After completion of dropping, the mixture was stirred at room temperature for about 3 hours, and it was confirmed by gas chromatography that no raw material remained, and then the reaction was terminated. The reaction solution was washed twice with saturated saline and then dried over anhydrous potassium carbonate. The potassium carbonate was filtered off and the solvent was removed to obtain 70 g of a crude product. This is purified by column chromatography (developing layer: silica gel, developing solvent: dichloromethane) to give a compound represented by the chemical formula (4) 25
g was obtained.

[0034]

[Chemical 4] Chemical formula (4)

A 1 liter four-necked flask equipped with a dropping funnel, a thermometer, and a hydrogen chloride exhaust pipe was charged with 3 parts of aluminum chloride.
2 g and 120 ml of dichloromethane were added, and 21 g of acetyl chloride was added dropwise over 2 hours while stirring. To this 4
-Bromo-2-fluoro-1-phenylbenzene 50 g
200 ml of a solution in which was dissolved in dichloromethane was added dropwise. After stirring for about 4 hours, the reaction was checked by gas chromatography. Since the raw material remained, 4 g of acetyl chloride and 5 g of aluminum chloride were added. After stirring for 3 hours, it was confirmed by gas chromatography that no raw material remained, and the reaction was completed. About 500 g of crushed ice was put into a 1 liter beaker, and the reaction solution was slowly added thereto. The aluminum chloride was completely inactivated by stirring with a mechanical stirrer for about 30 minutes. Then, the organic layer was washed twice with saturated saline and dried over anhydrous magnesium sulfate, and then the solvent was removed to obtain 57 g of the compound represented by the chemical formula (5).

[0036]

[Chemical 5] Chemical formula (5)

A 1-liter four-necked flask was equipped with a thermometer and a Dimroth condenser, and 750 ml of formic acid and 50 g of the compound represented by the chemical formula (5) were weighed. While stirring with a magnetic stirrer, 50 ml of 34.5% hydrogen peroxide solution was added, and heated with a mantle heater to reflux. The remaining amount of the raw material was occasionally checked by gas chromatography, and the reaction was stopped about 12 hours after the reduction of the raw material stopped. Cool the reaction in a fume hood with ice and
% Aqueous sodium sulfite solution was added to generate a sulfurous acid gas to decompose the peroxide. After confirming that the peroxide was completely decomposed with potassium iodide starch paper, the mixture was extracted twice with 500 ml of ethyl acetate. The extracted layers were collected and washed with water repeatedly to adjust the pH to about 4. Further, it was washed with a saturated sodium hydrogen carbonate aqueous solution for neutralization, and finally washed twice with a saturated saline solution. After drying the organic layer over anhydrous magnesium sulfate, the solvent was removed to obtain 50 g of a crude product. This is subjected to column chromatography (developing layer: alumina 500
g, developing solvent: toluene / ethyl acetate = 1/1) to obtain a compound represented by the chemical formula (6). Yield: 30 g, 70% yield.

[0038]

[Chemical 6] Chemical formula (6)

2 equipped with thermometer, dropping funnel, and nitrogen introducing tube
In a 00 ml four-necked flask, add 4- (4-bromo-2-
Fluorophenyl) phenol (30 g), dichloromethane (50 ml) and paratoluenesulfonic acid (10 mg) were added, and a solution (20 m) of 3,4-dihydropyran (18.9 g) in dichloromethane while keeping the temperature at 10 ° C or lower in an ice-cooled bath.
1 was added dropwise over 30 minutes. After stirring at room temperature for 4 hours, it was confirmed by gas chromatography that no raw material remained, and the reaction was completed. The reaction solution was washed with a saturated aqueous solution of sodium hydrogen carbonate and then with a saturated saline solution, dried over anhydrous potassium carbonate, and then the solvent was removed to obtain a crude product. Column chromatography (developing layer: silica gel, developing solvent: hexane / toluene / dichloromethane = 1/1)
30. The compound obtained by the chemical formula (7) after being purified by
5 g was obtained.

[0040]

[Chemical 7] Chemical formula (7)

In a 1-liter four-necked flask equipped with a nitrogen inlet tube, a Dimroth condenser, and a thermometer, 20.7 g of the compound of the chemical formula (4), 30 g of the compound of the chemical formula (7), 300 ml of dimethylformamide, 60 m of triethylamine.
1 g was added and 2.4 g of triphenylphosphine palladium and 0.98 g of copper iodide were added as a catalyst while stirring. Under a nitrogen atmosphere, it was heated to 90 ° C. with a mantle heater and reacted for about 4 hours. It was confirmed by thin layer chromatography that no raw material remained, and the reaction was terminated. Toluene (500 ml) was added to the reaction mixture, and the mixture was washed 3 times with saturated brine. After further drying with potassium carbonate, the solvent was removed to obtain a crude product. This was purified by column chromatography (developing layer: silica gel, developing solvent: toluene) to obtain 31 g of the compound represented by the chemical formula (8).

[0042]

[Chemical 8] Chemical formula (8)

500 equipped with Dimroth cooler and thermometer
In a 4-mL flask with a capacity of 4 ml, the compound of the formula (8) 10
g and 100 ml of tetrahydrofuran were put and heated to dissolve. To this, add 100 ml of 10% hydrochloric acid, and add about 30
Stir for minutes. It was confirmed by thin layer chromatography that no raw material remained, and the reaction was terminated. 500 ml of ethyl acetate was added to the reaction solution, and the mixture was washed twice with saturated saline. The organic layer was dried over magnesium sulfate and the solvent was removed to obtain the compound represented by the chemical formula (9). The reaction yield was quantitative.

[0044]

[Chemical 9] Chemical formula (9)

In a 50 ml four-necked flask equipped with a nitrogen inlet tube, a dropping funnel and a Dimroth condenser, 3.1 g (14.5 mmol) of maleimidohexanoic acid and 20 m of toluene were added.
1 was added and stirred. Under a nitrogen atmosphere, 13.1 g (62.4 mmol) of trifluoroacetic anhydride was added and stirred for 30 minutes. 2.0 g of the compound of the chemical formula (9) (6.
6 mmol) was added, and the mixture was heated on an oil bath and refluxed at 54 ° C. The reflux temperature gradually rises to 58 ° C after 4 hours.
Reached It was confirmed by thin layer chromatography that no raw material remained, and the reaction was terminated. The reaction solution was neutralized with a saturated aqueous solution of sodium hydrogen carbonate while cooling with an ice water bath. Extract with ethyl acetate, and extract the layer with saturated saline.
Washed twice. After drying over anhydrous sodium sulfate, the solvent was removed to obtain a crude product. Recrystallize with ethanol,
The obtained crystals were washed with methanol and then dried under reduced pressure to obtain the compound represented by the chemical formula (10). Yield: 2.5 g, yield: 56%.

[0046]

[Chemical 10] Chemical formula (10)

Example 1 Evaluation of Liquid Crystal Alignment Ability (Preparation of Composition for Photo Alignment Film) Compound 1 of Chemical Formula (10)
98 parts by mass of 1 part by mass of azobenzene derivative “Sudan IV” manufactured by Tokyo Kasei Co., Ltd.
What was melt | dissolved in N, N- dimethylformamide of a mass part, and what was filtered with the filter was set as the composition for optical alignment films.

[0048]

[Chemical 11] Formula (11)

(Photo-alignment operation) The composition for photo-alignment film is
It was evenly coated on a glass substrate with an ITO electrode by a spin coater and dried at 100 ° C. for 5 minutes. In the air, the obtained coating film surface was irradiated with parallel light from ultraviolet rays from an ultra-high pressure mercury lamp, which was linearly polarized by a polarization filter having an energy density of 15 mW / cm ² and a wavelength of 365 nm, from a direction perpendicular to the substrate. Irradiation was performed so that the integrated light amount was 1 J / cm ² . Next, from the direction perpendicular to the polarization direction of the linearly polarized light that was previously irradiated and at 45 ° to the substrate surface, the parallel light of unpolarized ultraviolet light having an energy density of 40 mW / cm ² and a wavelength of 365 nm was integrated. Of 5 J / cm ² for photo-alignment.

(Fixation of Orientation) Next, the glass substrate was placed on a hot plate and heated at 180 ° C. for 90 minutes to cure the coating film to fix the orientation.

(Production of Liquid Crystal Display Element) An epoxy adhesive containing styrene beads having a diameter of 8 μm was applied around the substrate having a photo-alignment film obtained by the above method, leaving a liquid crystal injection port, and an alignment surface was obtained. Are opposed to each other and are pressed in such a manner that the directions of the irradiated polarized light are parallel to each other and pressure-bonded, and the adhesive is cured at 150 ° C. for 90 minutes. Next, 0.2% from the liquid crystal injection port, Dainippon Ink and Chemicals, Inc.
Anthraquinone derivative "M-137" manufactured by Dainippon Ink and Chemicals, Inc. nematic liquid crystal "11-332"
3 "was injected into the liquid crystal composition at 100 ° C., which is an isotropic phase, and then the liquid crystal injection port was sealed with an epoxy adhesive to obtain a liquid crystal display element. For this, the liquid crystal alignment ability and the pretilt angle were evaluated.

The liquid crystal alignment ability was evaluated by the order parameter and the pretilt angle. [Order parameter] The order parameter value was calculated from the absorbance, and the orientation and the orientation direction were evaluated. A polarized visible UV spectrophotometer was used for the absorbance measurement. The absorbance of the dichroic molecule M-137 in the liquid crystal composition used in Example 1 for linearly polarized light having a wavelength of 625 nm was measured, and the order parameter value was calculated according to the formula (1).

[0053]

[Formula 1]

(In the formula, A _// represents the absorbance when the polarization direction of the polarized light irradiated for the orientation of the photo-alignment film and the polarization direction of the incident polarized light for measuring the absorbance are parallel, and A _//
⊥ represents the absorbance when the polarization direction of the polarized light irradiated for the orientation of the photo-alignment film is perpendicular to the polarization direction of the incident polarized light for measuring the absorbance. At this time, the order parameter S shows a positive value when the alignment direction of the liquid crystal molecules is parallel to the polarization direction with which the photo-alignment film is irradiated, and a negative value when it is vertical. In addition, the larger the absolute value of S, the higher the orientation. )

As a result, the order parameter of the liquid crystal display device produced in Example 1 was -0.75, indicating that the liquid crystal molecules had a high alignment property and the polarization of the polarized light irradiated for the alignment of the photo-alignment film. It was found that the orientation was perpendicular to the polarization direction.

[Pretilt Angle] The pretilt angle is measured by T.W. J. Schffer, et al. J. App
l. Phys. , Vol. 48,1783 (1977)
According to the crystal rotation method described in 1. As a result, the pretilt angle was 4.8 °.

Example 2 Evaluation of Light Stability Regarding the light stability, the alignment stability after irradiating the prepared photo-alignment film with polarized light in different directions was evaluated. A composition for a photo-alignment film was prepared in the same manner as in Example 1, and the composition was applied onto a substrate,
After the photo-alignment operation, a coating with fixed orientation was obtained. Further, the coating film was irradiated with 365 nm ultraviolet light having a polarization direction different from that of the light irradiated from the direction perpendicular to the substrate by the photo-alignment operation to prepare a substrate with a photo-alignment film. Example 1
A liquid crystal display device was prepared in the same manner as in, and the order parameter was measured. As a result, the order parameter is −
It was 0.75, and no change was observed as compared with Example 1. No change was observed in the pretilt angle.

[Comparative Example 1] A liquid crystal display device was produced in the same manner as in Example 1 except that the composition for photo-alignment film consisting of "Sudan IV" was used. When the liquid crystal alignment ability was evaluated by the same method as in Example 1, the order parameter was −0.74, which was almost the same as that of the liquid crystal display element of Example 1.

[Comparative Example 2] A liquid crystal display device was produced in the same manner as in Example 2 except that the composition for photo-alignment film consisting of "Sudan IV" was used. When the liquid crystal aligning ability was evaluated by the same method as in Example 2, the order parameter was +0.62, and the direction was changed to be perpendicular to the alignment direction of the photo-alignment film obtained in Comparative Example 1. From this, it was found that the alignment state was unstable to light irradiation.

[Example 3] Photopolymerization was initiated on a liquid crystal composition "UCL-001" manufactured by Dainippon Ink and Chemicals, Inc. containing 50% of each of two types of liquid crystals represented by the formula (12). "Irgacure 65" manufactured by Ciba Geigy
1 "was added at 1% to obtain a composition. 1 part by mass of the composition and 1 part by mass of "Sudan IV" were mixed, dissolved in 98 parts by mass of N, N-dimethylformamide, and filtered through a filter to obtain a composition for a photo-alignment film. This was subjected to a photo-alignment operation in the same manner as in Example 1, and then, onto the glass substrate,
Under a nitrogen atmosphere, unpolarized ultraviolet rays having a wavelength of 365 nm and a light amount of 1 J / cm ² were irradiated to cure the coating film and fix the orientation.

Using the substrate with a photo-alignment film obtained by the above method, a liquid crystal display device was produced in the same manner as in Example 1 and the liquid crystal alignment ability was evaluated. As a result, the order parameter was 0.68. Further, as a result of manufacturing a liquid crystal display device and evaluating the light stability in the same manner as in Example 2, the order parameter was 0.65, which was almost unchanged.

[0062]

[Chemical 12] Formula (12)

[0063]

The composition for a photo-alignment film of the present invention contains a dichroic molecule and a radical-polymerizable monomer having a mesogenic group, and therefore has good alignment characteristics such as a large pretilt angle and order parameter. It is possible to obtain a photo-alignment film having Moreover, since the oriented dichroic molecule is fixed by the copolymer obtained by orienting and polymerizing the radical-polymerizable monomer, a photo-alignment film stable to heat and light can be obtained.

Claims (5)

[Claims] 1. A composition for a photo-alignment film, comprising a dichroic molecule and a radical-polymerizable monomer having a mesogenic group. 2. The composition for a photo-alignment film according to claim 1, wherein the dichroic molecule is an azobenzene derivative. 3. The composition for a photo-alignment film according to claim 1, wherein the polymerizable group of the radically polymerizable monomer is a maleimide group. 4. The composition for a photo-alignment film according to claim 1, wherein the radically polymerizable monomer is a monomer having a mesogen group and two or more maleimide groups in one molecule. 5. A composition for a photo-alignment film containing a dichroic molecule and a radical-polymerizable monomer having a mesogenic group is coated on a substrate, and linearly polarized or at an oblique direction of a wavelength absorbed by the dichroic molecule. After photo-aligning the dichroic molecule and the radical-polymerizable monomer having a mesogenic group by irradiating non-polarized light from the above, the radical-polymerizable monomer is polymerized by heating or irradiating with light. A method for producing a photo-alignment film, comprising: