JP2001048904A - Production method for liquid crystal orientation membrane and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method for liquid crystal orientation membrane excellent in productivity, stability of orientation such as heat resistance, etc., without requiring a preliminary heating process at high temperature and a long time. SOLUTION: A monomer is polymerized by irradiating the monomer with an anisotropic light. The monomer is polymerized by irradiating the monomer with the anisotropic light after coating a solution comprising the monomer and a solvent having low boiling point to a substrate. Monomers having acrylate group or methacrylate group are used as the monomer or an oligomer. An oriented polymer membrane is obtained by coating the monomer on the substrate and then irradiating the monomer with UV. Various liquid monomers, etc., are directly coated on the substrate. Solid monomers generally dissolving more easily than polymers are capable of using a solvent having low boiling point and a preliminary heating process at high temperature and a long time required in conventional method is not required in the process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a liquid crystal alignment film, and more particularly to a method for producing a liquid crystal alignment film that imparts liquid crystal alignment ability by irradiating light.

[0002]

2. Description of the Related Art At present, in a liquid crystal display (LCD) widely used as a display device, it is necessary to align liquid crystal molecules in one direction at a substrate interface. An alignment film for orienting in the direction is provided. A rubbing method in which a surface of a polymer such as polyimide is mechanically rubbed with a rayon cloth, a nylon cloth, or the like is widely used as a method for manufacturing an alignment film. However, since the rubbing method is a technique of mechanically rubbing the surface of a polymer, fine dust is generated at the time of rubbing, active elements such as TFTs are destroyed due to generation of static electricity due to friction, and unevenness over a wide range. There is a problem that it is difficult to orient uniformly without any other method.

As a method of manufacturing an alignment film which overcomes such a disadvantage of the rubbing method, a method of manufacturing a non-contact type liquid crystal alignment film using light is known. As a method for producing a liquid crystal alignment film using light, see NATURE 351, p. 49 (1
991) and a method using an anisotropic absorbing molecule such as an azo dye disclosed in JP-A-2-27725, Proc. IDR
C94 p. 213, a method using the polyimide disclosed in Jpn. J. Appl. Phys. , 3
1, p. 2155 (1992) and JP-A-5-2324
A method using a polymer having a photoreactive group in the side chain disclosed in No. 73 is known.

In the method using an anisotropic absorbing molecule such as an azo dye disclosed in Japanese Patent Application Laid-Open No. 2-277625, a mixed solution containing an anisotropic absorbing molecule such as an azo dye and a polyimide is applied to a substrate, and the solvent is removed. Then, by irradiating polarized laser light to obtain a thin film, an alignment film having anisotropy is obtained (Example 10 and the like). Proc. IDRC 94 p. 2
In the method using polyimide disclosed in No. 13, an alignment film having anisotropy is obtained by irradiating polarized light to a polyimide thin film on a substrate usually used as an alignment film for rubbing. In the method using a polymer having a photoreactive group in a side chain disclosed in JP-A-5-232473, a solution of a side-chain type polymer such as polyvinyl cinnamate having a side chain that causes a photodimerization reaction is applied to a substrate. After removing the solvent to form a thin film, the film is irradiated with polarized light to obtain an alignment film having anisotropy.

[0005]

However, the above-mentioned conventional method for manufacturing an alignment film has the following problems. The alignment film used in these manufacturing methods is a solid polymer material.To prepare a polymer thin film on the substrate surface, dissolve the polymer in a suitable solvent in advance to make a dilute solution, and then apply it to the substrate. It is necessary to apply and produce a thin film on a substrate. However, a solvent having a high boiling point is generally required to dissolve these polymers, and a high-temperature and long-time heat pretreatment step is required to remove the solvent after the application of the alignment film solution.

[0006] JP-A-2-277525, Proc. ID
RC 94 p. 213, polyimide is used. However, when the polyimide is a polyamic acid type, a high temperature of about 200 ° C.,
A calcination step that takes a long time is required. In the case of a soluble polyimide, NMP (N-methylpyrrolidone, boiling point 2
Polyimide can be dissolved only in a solvent having a high boiling point (e.g., 02 ° C.), so that a high-temperature and long-time heating pretreatment step is required in order to remove the solvent used for forming a thin film, similarly to the conventional rubbing method. Also, in a method using a polymer having a photoreactive group in a side chain such as polyvinyl cinnamate, in order to dissolve a polymer having a bulky side chain, a polymer such as methylcellosolve acetate (boiling point 145 ° C.) is used. A boiling point solvent must be used, and again a high-temperature heating pretreatment step is indispensable.

The alignment film obtained by the conventional method for manufacturing a liquid crystal alignment film has a problem in alignment stability. In the method using an anisotropic absorbing molecule such as an azo dye, since the azo compound causes an isomerization reaction by light, the orientation anisotropy caused by polarized light irradiation is unstable, and the subsequent light irradiation causes anisotropy. Is reduced. Further, it is considered that anisotropic absorbing molecules such as azo dyes exist in a low molecular state in polyimide, and such anisotropic absorbing molecules dissolve in a liquid crystal layer after a liquid crystal cell is formed, and the There is a problem that the characteristics may be deteriorated.

In the method using polyimide, it is considered that the orientation anisotropy is caused by the decomposition reaction of the polyimide chain by UV light. However, since polyimide is a polymer having high stability and low reactivity, it is anisotropic. It is necessary to irradiate UV for a long time for sex development. On the other hand, due to the degradation of the polyimide chain due to such long-time UV irradiation,
It is conceivable that a problem occurs in the reliability of the manufactured LCD.

In the method using a polymer having a photoreactive group in a side chain such as polyvinyl cinnamate, the side chain is stabilized by a dimerization reaction, but the main chain is composed of only a flexible single carbon bond chain. Therefore, sufficient heat resistance cannot be obtained. In particular, when a thermosetting resin is used for fixing the upper and lower substrates, a high-temperature heat treatment step of about 160 ° C. is performed for curing the thermosetting resin, and thus the liquid crystal alignment ability cannot be maintained in this heating step. There is. Further, since polyvinyl cinnamate also causes a photoisomerization reaction, if unreacted cinnamate groups remain, there is a problem that the orientation is unstable due to the photoisomerization reaction. Further, there is a problem that the types of polymers having photoreactivity in the side chain are significantly limited.

An object of the present invention is to provide a liquid crystal alignment film which avoids the above-mentioned problems, eliminates the need for a high-temperature and long-time heating pretreatment step, and is excellent in productivity as well as in alignment stability such as heat resistance. Is to provide a way.

[0011]

The method for producing a liquid crystal alignment film of the present invention is characterized in that monomers or oligomers are irradiated with anisotropic light to cause a reaction. Further, the method for producing a liquid crystal alignment film of the present invention is characterized in that a solution comprising a monomer or oligomer and a low-boiling solvent is applied to a substrate, and then the monomer is reacted by irradiating anisotropic light. As such a monomer or oligomer, particularly, a monomer or an oligomer having an acrylate group or a methacrylate group, and a monomer having two or more acrylate or methacrylate groups in one molecule can be preferably used. Monomers or oligomers having a vinyl group can also be used.

In the method for producing a liquid crystal alignment film of the present invention, unlike a conventional alignment film in which a polymer solution is applied to a substrate, a monomer is applied to the substrate and irradiated with UV to form a polymer alignment film. . A polymer is generally a solid, but a monomer or the like has a large amount of liquid and can be directly applied to a substrate. In this case, since a solvent is not used, a heating pretreatment step for baking polyimide, removing the solvent, and the like, which is indispensable in a conventional method for producing a liquid crystal alignment film, is unnecessary.

Some of the monomers are solid at room temperature for reasons such as high molecular weight. However, even such a solid monomer is generally superior in solubility to a polymer and therefore has a low boiling point. Solvents can be used.
By using a solvent having a low boiling point, the high-temperature, long-time heating pretreatment step required by the conventional method becomes unnecessary,
Productivity is improved.

In the case where a solid monomer or the like is used as a solution and applied to a substrate, if the solvent is completely removed, deposition and crystallization of the monomer solid will occur, and a thin film cannot be formed on the substrate. Therefore, when the monomer is a solid, it is desirable that the monomer be reacted by irradiating light with the solvent remaining at the time of coating. From this viewpoint, a solvent having a melting point of about 100 ° C. and hardly volatilizing to some extent at room temperature is desirable, and a solvent such as toluene is also desirable from the viewpoint of excellent wettability to a glass substrate or the like. Note that the orientation film is usually as thin as about several tens to hundreds of nm, so that even with a solvent having a boiling point of about 100 ° C., the heating pretreatment step can be omitted.

In the case of a solid polymer, the reaction site is linked by the polymer and the movement of the polymer chain is poor, so that the reaction takes a long time. On the other hand, the monomer is not easily linked, and the molecular movement is easy. In addition, there is an advantage that a reaction occurs in a short time. Also, an acrylate group,
Since a methacrylate group has high reactivity to light, a good alignment film can be obtained with a small amount of UV irradiation and a short UV irradiation time by using a monomer having an acrylate group and a methacrylate group.

When a monomer or the like having a polyfunctional acrylate group is used, a strong network structure is produced by a polymerization reaction after light irradiation, so that it has high heat resistance and is stable without change over time. An alignment film is obtained.

Further, in the conventional alignment film using a polymer, a special structure is required for a side chain, and the range of selection of a compound is extremely limited. On the other hand, a monomer or the like is used. In the present invention, the range of selection of the compound is large.
In particular, acrylate monomers, vinyl monomers, and the like are widely used as ultraviolet-curable resins. Monomers having various molecular structures can be obtained, and synthesis methods are widely known and can be easily synthesized.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The "monomer" used in the method for producing a liquid crystal alignment film of the present invention refers to a compound comprising one repeating unit which is a precursor of a polymer.
For example, such as methyl methacrylate relative to polymethyl methacrylate. Usually, polymers have large molecular weights of thousands to tens of thousands or more, whereas monomers have rather small molecular weights of tens to hundreds. Therefore, it dissolves in many solvents including low-boiling solvents.

An "oligomer" is one in which a plurality of monomers are chemically bonded, and the number of repeating units bonded is from several to about ten. Oligomers are larger than monomers, but much smaller than polymers, and are more soluble. Therefore, it dissolves in the same low boiling point solvent as the monomer.

The monomers and oligomers used in the method for producing a liquid crystal alignment film of the present invention are liquids or the like and can be applied to a substrate or the like, or can be dissolved in a low boiling point solvent and applied to a substrate. Needs to be Further, the monomers and oligomers used in the method for producing a liquid crystal alignment film of the present invention must be those that can be polymerized by irradiating anisotropic light. Examples of such a monomer or oligomer include a monomer or oligomer having an acrylate group or a methacrylate group.
In particular, from the viewpoint of heat stability such as heat resistance, a monomer or oligomer having two or more acrylate groups or methacrylate groups in one molecule, which forms a network structure after polymerization, is desirable.

The monomers or oligomers having an acrylate or methacrylate group used in the present invention include 2-ethylhexyl acrylate, butyl ethyl acrylate, butoxyethyl acrylate, 2-cyanoethyl acrylate, benzyl acrylate, cyclohexyl acrylate, and 2-hydroxypropyl acrylate. , 2-ethoxyethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, isobonyl acrylate, isodecyl acrylate , Lauryl acrylate, morpholine acrylate, phenoxyethyl acrylate Phenoxydiethylene glycol acrylate, 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,3 Monofunctional acrylate compounds such as 4,4,4,4-hexafluorobutyl acrylate,
2-ethylhexyl methacrylate, butylethyl methacrylate, butoxyethyl methacrylate, 2-cyanoethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, 2-hydroxypropyl methacrylate, 2-ethoxyethyl acrylate,
N, N-diethylaminoethyl methacrylate, N, N
-Dimethylaminoethyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, isobonyl methacrylate, isodecyl methacrylate, lauryl methacrylate, morpholine methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate,
2,2,2-trifluoroethyl methacrylate, 2,
2,3,3-tetrafluoropropyl methacrylate,
Monofunctional methacrylate compounds such as 2,2,3,3,4,4-hexafluorobutyl methacrylate can also be used, but from the viewpoint of producing a stable network structure after the reaction, 4,4′-bisacryloyl Oxybiphenyl,
4,4'-biphenyldiacrylate, diethylstilbestrol diacrylate, 1,4-bisacryloyloxybenzene, 4,4'-bisacryloyloxydiphenylether, 4,4'-bisacryloyloxydiphenylmethane, 3.9-bis [1,1-dimethyl-2-acryloyloxyethyl] -2,4,8,10
-Tetraspiro [5,5] undecane, α, α'-bis [4-acryloyloxyphenyl] -1,4-diisopropylbenzene, 1,4-bisacryloyloxytetrafluorobenzene, 4,4'-bisacryloyloxyocta Fluorobiphenyl, diethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, dicyclopentanyl diacrylate, glycerol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate , Tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ditrimethylolpropane Laacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, 4,4′-diacryloyloxydimethylstilbene, 4,4′-diacryloyloxydimethylstilbene, 4,4′-diacryloyloxydiethylstilbene, 4,4'-Diacryloyloxydipropylstilbene, 4,4'-Diacryloyloxydibutylstilbene, 4,4'-Diacryloyloxydipentylstilbene, 4,4'-Diacryloyloxydihexylstilbene, 4,4'-di Acryloyloxydifluorostilbene, 2,2,3
3,4,4-hexafluoropentanediol-1,5
Diacrylate, 1,1,2,2,3,3-hexafluoropropyl-1,3-diacrylate, bifunctional and polyfunctional acrylate compounds such as urethane acrylate oligomer, diethylene glycol dimethacrylate,
4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, dicyclopentanyl dimethacrylate glycerol dimethacrylate, 1,6
-Hexanediol dimethacrylate, neopentyl glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, pentaerythritol trimethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol mono Hydroxypentamethacrylate, 2,2
3,3,4,4-hexafluoropentanediol-
There are bifunctional and polyfunctional methacrylate compounds such as 1,5-dimethacrylate and urethane methacrylate oligomer. Further, as a matrix resin precursor containing elemental fluorine, 2,2,3,3,4,4-hexafluoropentanediol-1,5-diacrylate, 1,1,2,2
2,3,3-hexafluoropropyl-1,3-diacrylate, 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3 3-tetrafluoropropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2, Examples include compounds containing 2,3,4,4,4-hexafluorobutyl methacrylate, fluorine-containing urethane acrylate oligomers, etc., but are not limited thereto.

In order to polymerize by irradiating anisotropic light, it is desirable that the light absorbing property is large and the light absorbing property has anisotropy. In addition, the liquid crystal material generally has a structure in which benzene rings are connected. Because it is desirable to have
It is desirable to use a monomer represented by the following formula (1) or a monomer represented by the following formula (2) similar to this.

[0023]

Embedded image (Where, E is an -H or -CH _3, X is

Embedded image Represents A is a direct bond, -O-, -CO-, -OCO
-, - COO -, - CH 2 -, - C (CH 3) 2 -, - C
H = CH -, - CF = CF -, - C (C n H 2n + 1) = C
_{(C n H 2n + 1)} -,

Embedded image R represents an alkyl chain (n represents an integer of 0 to 4) or -F.

[0024]

Embedded image (Where, E is an -H or -CH _3, X is

Embedded image Represents A is a direct bond, -O-, -CO-, -OCO
-, - COO -, - CH 2 -, - C (CH 3) 2 -, - C
H = CH -, - CF = CF -, - C (C n H 2n + 1) = C
_{(C n H 2n + 1)} -,

Embedded image R represents an alkyl chain (n is any integer or decimal number from 0 to 4) or -F. Y is-(C
_{H 2) n -, - (} CH 2) n -O -, - O- (CH 2) n -
(N is an integer of 1 or more).

A part of the monomer having the above structure is a monomer having a liquid crystal property. From the property of the alignment film that aligns the liquid crystal, a liquid crystalline monomer whose monomer has liquid crystallinity is also desirable in the present invention.

The monomers and oligomers can be used alone or as a mixture of two or more. From the viewpoint of the stability of the alignment film after light irradiation, the monomer mixture preferably contains at least one kind of polyfunctional compound.

A photopolymerization initiator can be added to the monomer and the like. Examples of the photopolymerization initiator include acetophenone type, benzoin type, benzophenone type, thioxanthone type and the like. For example, camphorquinone, 5,7-iodo-3-butoxy-6-fluorene, diethoxyacetophenone, 2-hydroxy-2 -Methyl-1-phenylpropan-1-one, benzoin methyl ether, benzoin ethyl ether, 4-phenylbenzophenone,
There are 2-chlorothioxanthone, 2-methylthioxanthone and the like and derivatives of these compounds.

If necessary, a photoinitiating auxiliary such as methyldiethanolamine, 4-dimethylaminobenzoic acid, or a photosensitizing dye can be added, so that light having a wide range of wavelengths can be used in the reaction. it can.

In the method for producing a liquid crystal alignment film according to the present invention, when the monomer or oligomer is a solid, or when it is difficult to apply the liquid to a substrate, for example, when the viscosity is too high for producing a thin film even if the monomer or the oligomer is a liquid. Use a low boiling solvent. The low-boiling solvent referred to in the present invention refers to a solvent for a high-boiling solvent such as NMP used in a conventional alignment film or the like, and the boiling point does not necessarily need to be around room temperature. It is included in the low-boiling point solvent referred to above. As the low boiling point solvent used in the present invention, acetone (boiling point: 56.3 ° C.), acetonitrile (81.6 ° C.), benzene (80.1 ° C.), chloroform (61.2 ° C.), carbon tetrachloride (76 ° C.) .8
° C), ethanol (78.5 ° C), methanol (64.
7 ° C.), methyl acetate (57.8 ° C.), ethyl acetate (77
° C), isopropyl acetate (101.6 ° C), hexane (68.6 ° C), isopropyl ether (68 ° C), methanol (64.7 ° C), methylene chloride (40.0 ° C).
° C), methyl ethyl ketone (79.6 ° C), tetrahydrofuran (66 ° C), toluene (110.6 ° C), xylene (138.4 ° C), isopropanol (82.3 ° C).
° C), n-propanol (97.8 ° C), isobutanol (107.9 ° C), ethyl ether (35 ° C) and the like.

As a solvent for preparing an alignment film, a solvent having good wettability to a substrate is desirable. For this reason, it is also possible to previously treat the substrate surface with a surface treatment agent such as a coupling agent.

When a monomer or the like is a solid and is applied to a substrate using a solvent, if the solvent is removed, solid deposition or crystallization occurs, and a thin film cannot be formed on the substrate in some cases. Therefore, when the monomer is a solid, it is desirable that the monomer be reacted by irradiating light with the solvent remaining at the time of application. From this viewpoint, a solvent having a melting point close to 100 ° C. and not volatilizing to some extent even at room temperature is desirable. A solvent such as toluene is desirable also from the viewpoint of excellent wettability to a glass substrate or the like.

For applying the monomer or the monomer solution to the substrate, a printing method or the like can be used in addition to the spin coating method.

The method for producing a liquid crystal alignment film of the present invention is characterized in that a monomer or an oligomer is provided with liquid crystal alignment ability by irradiating anisotropic light. Polarized light can be given as such anisotropic light. Polarized light includes linearly polarized light as well as partially polarized light. In addition, even in the case of non-polarized light such as natural light, irradiation from a diagonal direction (other than the normal direction of the substrate) results in a difference in irradiation intensity between the polarization plane and the vertical direction. It has the same effect as in the case. Therefore, the present invention includes such non-polarized oblique irradiation. The irradiation of the linearly polarized light and the partially polarized light may be irradiation from an oblique direction. Thereby, a pretilt angle can be given to the alignment of the liquid crystal. Irradiation from an oblique direction may be performed, irradiation may be performed twice or more, and an arbitrary pattern can be formed using a light shielding film such as a photomask. In particular, irradiation from an oblique direction or irradiation twice is effective for generating a pretilt angle necessary for another liquid crystal display device of the present invention.

In the present invention, since a micro non-uniform structure is not produced by utilizing the coherence of light, the light does not need to have coherence like a laser, and is usually used. An inexpensive light source can be used, and there is no need for simultaneous irradiation of a plurality of lights.

The wavelength of the irradiation light is desirably in the region where the monomer or the like is absorbed (in the system to which the initiator is added, the region where the monomer or the initiator is absorbed), and generally, ultraviolet light is desirable. As a light source that generates such light,
Ultra high pressure, high pressure, low pressure mercury lamp, xenon lamp,
UV lamps such as excimer lamps with a narrow wavelength range, Kr
An ultraviolet laser light source such as F or ArF, or a device that converts a visible or infrared laser beam into a harmonic by using a non-linear element or the like and converts it into ultraviolet light can be used.

As the polarized light, the light from the light source passes through a polarizing film, a polarizing prism, and a laminated polarizing plate disposed at a Brewster's angle with respect to the incident angle of the laminated quartz substrate.
It can be obtained by using polarized laser light or the like.

In the method for producing an alignment film according to the present invention, it is considered that the reaction occurring in the monomer or oligomer by irradiating anisotropic light is mainly a polymerization reaction due to a condensation reaction of an acrylate group, a methacrylate group or the like. Can be However, since ultraviolet light has high energy, a reaction at another site such as a benzene ring may occur. If it is a reaction for imparting liquid crystal alignment ability, the "reaction" in the present invention
Includes such a reaction. The atmosphere at the time of light irradiation is preferably a nitrogen atmosphere from the viewpoint of the stability of radicals generated by the light irradiation, but may be an oxygen atmosphere such as the air.

FIG. 1 shows an example of a liquid crystal display device using the liquid crystal alignment film of the present invention. FIG. 1 shows a twisted and nematic (TN) type liquid crystal display device.
The present invention is not limited to the N type, but may be the STN type, the lateral electric field type (I
PS), ferroelectric liquid crystal and the like.

The liquid crystal display device using the liquid crystal alignment film of the present invention includes electrodes 22, 32, alignment films 21, 3 of the present invention.
A liquid crystal material 11 between the upper and lower substrates 23 and 33
Is pinched. In the TN mode, the liquid crystal material 11 is processed by the alignment films 21 and 31 to have a twist close to 90 °.

The liquid crystal display device of the present invention may be one in which each pixel is composed of a single region, but is of a pixel division type in which each pixel is divided into a plurality of regions having different alignment directions. You may. As such a pixel division type,
There are two divisions and four divisions.

The liquid crystal layer of the liquid crystal display device of the present invention may be composed of only a liquid crystal material, but may be composed of one containing a chiral agent for defining the twist direction of the liquid crystal, one containing a polymer solid, a polymer network or the like. There may be.

In the liquid crystal display device of the present invention, a method for applying a voltage to both electrodes may be a static drive for applying a constant voltage, or a dynamic drive for applying a changing voltage. Further, the dynamic drive may be a simple matrix drive or a TF
An active matrix such as T or MIM may be used.

Although the description has been given based on the transmission type liquid crystal display device, the liquid crystal display device of the present invention is not limited to the transmission type liquid crystal display device, but may be a reflection type liquid crystal display device. In this case, one of the substrates does not need to be transparent, and when the substrate is opaque, when the substrate is a mirror surface or other reflective surface, or when the substrate also serves as an electrode, the liquid crystal display device of the present invention is also used. include.

[0044]

Next, an embodiment of the present invention will be described in detail. (Reference Example 1) In an argon gas atmosphere, 30 ml of a tetrahydrofuran solution containing 3 g of desoxy anisoin (manufactured by Aldrich) was dropped into a tetrahydrofuran suspension containing 3.3 g of lithium aluminum hydride at room temperature over 2 hours. After 3 hours of boiling point reflux, ethyl acetate 30
ml was added to quench excess reducing agent. 3 ml of methanol, 12 ml of water, 60 ml of a 20% aqueous solution of sulfuric acid and 50 ml of ethyl acetate were added, and only the ethyl acetate layer was extracted and concentrated to obtain a yellow solid.

To 2 g of the yellow solid, 20 ml of toluene and a catalytic amount of p-toluenesulfonic acid were added, and the mixture was refluxed at the boiling point until no more water was generated. The toluene was removed under reduced pressure to obtain a white solid (4,4'-dimethoxystilbene).

A solution of 1 g of this white solid in dichloromethane 2
To 0 ml, BBr ₃ was added and stirred at room temperature for 8 hours.
The dichloromethane reaction solution was dropped into 50 ml of stirring ice water,
200 ml of ethyl acetate was added, and the organic layer was separated and concentrated to obtain a white powder (4,4′-dihydroxystilbene).

To a solution consisting of 0.5 g of this white powder, 30 ml of tetrahydrafuran, 1.6 ml of triethylamine and 0.005 g of phenothiazine was added 10 ml of a tetrahydrofuran solution containing 1.0 ml of acrylonitrile chloride over 0.5 hour under ice cooling. It was dropped. After the dropwise addition, the mixture was stirred under ice cooling for 1.5 hours and at room temperature for 2 hours. Methanol several ml
Was added to deactivate excess acrylonitrile chloride, then triethyl hydrochloride was removed with a filter, and tetrahydrofuran was removed from the resulting solution to obtain 4,4′-bisacryloyloxystilbene.

Reference Example 2 4,4'-biphenol 2
g, triethylamine 4 ml, phenothiazine 0.00
5 g was dissolved in 30 ml of tetrahydrofuran. To the above solution, 10 ml of a tetrahydrofuran solution containing 2.4 ml of acrylonitrile chloride was added dropwise over 0.5 hour under ice cooling. After the dropwise addition, the mixture was stirred under ice cooling for 1.5 hours and at room temperature for 2 hours. After a few ml of methanol was added to deactivate excess acrylonitrile chloride, triethyl hydrochloride was removed with a filter, and tetrahydrofuran was removed from the obtained solution to obtain 4,4'-bisacryloyloxybiphenyl.

Reference Example 3 Reference Example 2 was repeated except that 1 g of hydroquinone, 1 g of 4,4'-dihydroxydiphenyl ether and 1 g of 4,4'-bisacryloyloxydiphenylmethane were used instead of 4,4'-biphenol. And 1,4-bisacryloyloxybenzene, 4,4′-bisacryloyloxydiphenyl ether, and 4,4′-bisacryloyloxydiphenylmethane.

Example 1 A 25 mm × 35 mm substrate having an ITO (indium tin oxide) transparent electrode was coated with a monomer (4,4′-bisacryloyloxystilbene).
Was applied by a spin coating method (rotation speed: 2000 rpm).

The substrate with the monomer solution was irradiated with polarized UV light for 5 minutes under a nitrogen atmosphere without heat treatment. The polarized UV light is a UV light source (Ushio SPOTCUR)
UV light from EVIS 25100) was obtained through a Glan-Taylor prism. UV irradiation is 5 minutes, 1.0
J / cm ² .

An adhesive was applied to the periphery of the above-mentioned substrates, and the substrates produced in the same manner were bonded together while applying pressure so that the polarization directions of the irradiation polarized light of both substrates became parallel. The cell gap was adjusted using 5.0 μm latex spheres.

The empty cells thus prepared are placed in a vacuum chamber,
After evacuation, liquid crystal material (ZLI4792: manufactured by Merck)
Was injected. After the injection of the liquid crystal material was completed, the injection port was sealed.

When observed under a polarizing microscope crossed Nicols,
It is confirmed that when the polarization angle of the irradiated UV light coincides with the polarization plane of the polarizer or the analyzer, a dark field is formed and the liquid crystal is oriented in one direction when light and dark are generated at every rotation angle of the cell of 90 °. did it. When the light intensity ratio in the light and dark state is measured with a light meter,
Light / dark = 90/1.

(Example 2) After UV irradiation, two substrates
A liquid crystal cell was prepared in the same manner as in Example 1, except that the heat treatment was performed at 80 ° C. for 1 hour. Observation under a polarizing microscope crossed Nicols shows that the alignment state of the liquid crystal is the same as in the case where no heat treatment was performed, and the light amount ratio in the bright / dark state is 95/95.
It was one.

Example 3 The two substrates were bonded so that the polarization directions of the irradiated polarized light were orthogonal to each other.
A liquid crystal cell was prepared in the same manner as in Example 1 except that ZLI4792 to which a small amount of a chiral agent (S1011: manufactured by Merck) was added was used (TN cell). When observed under a polarizing microscope crossed Nicols, the alignment state of the liquid crystal is almost uniform,
The difference in brightness due to the rotation of the cell was small. When a voltage was applied to the cell, the field of view began to be darker than when 1.8 V (1 kHz rectangular wave) was applied, and the cell was completely dark at 5.0 V.

(Example 4) In place of 4,4'-bisacryloyloxystilbene, 1,4-
Bisacryloyloxybenzene, 4,4′-bisacryloyloxybiphenyl, 4,4′-biphenyldiacrylate, 4,4′-bisacryloyloxydiphenyl ether, and 4,4′-bisacryloyloxydiphenylmethane, respectively, A cell was produced in the same manner as in Example 1. In all the cells, the orientation of the liquid crystal was confirmed. When the light amount ratios in the bright and dark states were measured, they were 20/1, 80/1, 50/1, 70/1, 5/1, respectively.
It was 0/1.

Example 5 The following monomers were used in place of 4,4'-diacryloyloxystilbene

Embedded image A cell was prepared in the same manner as in Example 1, except that was used.
When observed under a polarizing microscope crossed Nicols, light and dark were generated at every rotation angle of the cell of 90 °, and the light amount ratio in the light and dark state was 80/1.

(Example 6) Acetonitrile (81.6 ° C), methylene chloride (40.0 ° C),
Hexane (68.6 ° C), isopropanol (82.3)
° C) and the spin coating rotation speed is 500r
A cell was prepared in the same manner as in Example 5, except that the pressure was changed to pm.
In all the cells, the orientation of the liquid crystal was confirmed. When the light quantity ratio in the light and dark state was measured, they were 20/1, 1 and 1, respectively.
5/1, 70/1, 30/1.

Example 7 A monomer (neopentyl glycol diacrylate, liquid) was placed on a 25 mm × 35 mm substrate having an ITO (indium tin oxide) transparent electrode.
Was applied by spin coating (rotation speed 3000 rpm)
m). The substrate coated with the monomer was irradiated with polarized UV light for 20 minutes under a nitrogen atmosphere. UV irradiation amount is 4.0 J / c
m ² .

A cell was fabricated in the same manner as in Example 1 by combining the above substrates. When observed under a polarizing microscope crossed Nicols, it was confirmed that light and dark were generated at every rotation angle of the cell of 90 °, and that the liquid crystal was oriented in one direction. When the light amount ratio in the light / dark state was measured with a light meter, the ratio was light / dark = 20/1.

Comparative Example 1 A solution of polyvinyl cinnamate in methylcellosolve acetate (monomer concentration 4.0 w
t%) is 25 mm × 35 mm having an ITO transparent electrode.
The substrate was applied by a spin coating method (at a rotation speed of 2000r).
pm), the polarized UV light is
Irradiated for minutes.

An adhesive was applied to the periphery of the above-mentioned substrates, and the substrates produced in the same manner were bonded together while applying pressure so that the polarization directions of the irradiation polarized light of both substrates became parallel (cell gap: 5.0 μm). The prepared empty cells were placed in a vacuum chamber, and after evacuation, a liquid crystal material (ZLI4792, manufactured by Merck) was injected. After the injection of the liquid crystal material was completed, the injection port was sealed. When observed under a polarizing microscope crossed Nicols, the liquid crystal was oriented in an arbitrary direction, and the light / dark ratio was 2/1 or less.

Comparative Example 2 Methylcellosolve Acetate Solution of Polyvinylcinnamate (Monomer Concentration 4.0 W
t%) is 25 mm × 35 mm having an ITO transparent electrode.
The substrate was applied by a spin coating method (at a rotation speed of 2000r).
pm). After heating the substrate on a hot plate at 100 ° C. for 30 minutes, the substrate was irradiated with polarized UV light for 5 minutes.

A liquid crystal cell was produced in the same manner as in Example 1 using two substrates heat-treated at 180 ° C. for one hour and two substrates not heat-treated. When observed under a polarizing microscope crossed Nicols, the liquid crystal was oriented in one direction (bright / dark = 70/1) in the cell without heat treatment.
No liquid crystal orientation was observed on the substrate that had been heat-treated for a period of time.

[0066]

As described above, according to the present invention, high temperature,
It is possible to provide a method for producing a liquid crystal alignment film that does not require a long-time heating pretreatment step, is excellent in productivity, and is excellent in alignment stability such as heat resistance. This effect is achieved by using monomers and oligomers and by using low boiling solvents.

[Brief description of the drawings]

FIG. 1 is a diagram of a liquid crystal display device using a liquid crystal alignment film manufactured according to the present invention.

[Explanation of symbols]

 11 Liquid Crystal Molecules 21, 31 Alignment Film 22, 32 Transparent Electrode 23, 33 Glass Substrate 24, 34 Polarizing Film

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomohisa Goto 5-7-1 Shiba, Minato-ku, Tokyo F-term within NEC Corporation 2H090 HB13Y HC05 MB14 4J011 AC04 QA03 QA04 QA12 QA13 QA15 QA19 QA22 QA23 QA24 QA32 QA33 QA38 QA39 QA45 QA46 QB03 SA01 SA02 SA04 SA06 SA12 SA21 SA22 SA31 SA32.

Claims (11)

[Claims] 1. A method for producing a liquid crystal alignment film, wherein a monomer or an oligomer is irradiated with anisotropic light to cause a reaction. 2. A method for producing a liquid crystal alignment film, comprising applying a solution comprising a monomer or an oligomer and a low-boiling solvent to a substrate, and then irradiating anisotropic light to react the monomer or the oligomer. 3. A method comprising applying a solution comprising a monomer or oligomer and a low-boiling solvent to a substrate and irradiating anisotropic light with the low-boiling solvent remaining to react the monomer or oligomer. A method for producing a liquid crystal alignment film. 4. The method for producing a liquid crystal alignment film according to claim 1, wherein the monomer or oligomer is a monomer or oligomer having an acrylate group or a methacrylate group. 5. The method for producing a liquid crystal alignment film according to claim 1, wherein the monomer or oligomer has two or more acrylate groups or methacrylate groups in one molecule. 6. The method according to claim 1, wherein the monomer or oligomer is a monomer or oligomer having a vinyl group. 7. The method for producing a liquid crystal alignment film according to claim 1, wherein the monomer is a compound represented by the following formula (1). Embedded image (Where E is —H or —CH ₃ , and X is Represents A is a direct bond, -O-, -CO-, -OCO
-, - COO -, - CH 2 -, - C (CH 3) 2 -, - C
H = CH -, - CF = CF -, - C (C n H 2n + 1) = C
(C _n H _{2n + 1} )-, R represents an alkyl chain (n represents an integer or a decimal number of any of 0 to 4) or -F. 8. The method according to claim 1, wherein the monomer is a compound represented by the following formula (2). Embedded image (Where E is —H or —CH ₃ , and X is Represents A is a direct bond, -O-, -CO-, -OCO
-, - COO -, - CH 2 -, - C (CH 3) 2 -, - C
H = CH -, - CF = CF -, - C (C n H 2n + 1) = C
(C _n H _{2n + 1} )-, R represents an alkyl chain (n is an integer of 0 to 4) or -F. Y _{is, - (CH 2) n -} ,
— (CH ₂ ) _n —O— or —O— (CH ₂ ) _n — (n represents an integer of 1 or more). 9. The method for producing a liquid crystal alignment film according to claim 1, wherein the anisotropic light is ultraviolet light. 10. The method according to claim 1, wherein the anisotropic light is any one of linearly polarized light, partially polarized light, and oblique irradiation light.
9. The method for producing a liquid crystal alignment film according to any one of items 8 to 8. 11. A liquid crystal display device including a liquid crystal alignment film produced by the method according to claim 1. Description: