JP2005292241A - Optical anisotropic substance and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily obtaining an anisotropic substance consisting of a partial structure which is free of an alignment defect and has high resolution and different optical anisotropy. <P>SOLUTION: The optical anisotropic substance, which is formed between two substrates, has a plurality of alignment regions nearly in parallel to one substrate and different in alignment direction on the one substrate and also has alignment nearly perpendicular to the other substrate, and the method for manufacturing the optical anisotropic substance in which a liquid crystal compound having a polymerizable function group is sandwiched between substrates opposed with a surface having liquid crystal alignment capability and they are polymerized with an active energy beam or heat while the liquid crystal material is aligned, the substrates being a substrate having a plurality of regions which are nearly parallel to the substrates and capable of aligning liquid crystal in different directions and two substrates capable of aligning liquid crystal nearly perpendicularly to the substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical anisotropic body having a hybrid structure with different orientation directions with respect to one substrate, and a hybrid structure obtained by polymerizing a polymerizable liquid crystal composition in a different orientation state with respect to one substrate. The present invention relates to an optically anisotropic body having:

  Liquid crystals are used as display elements, and recently, the phase of light is controlled using the birefringence of aligned liquid crystals. Among them, optical anisotropic bodies that have different alignment regions such as hybrid alignment, in which the alignment direction of the liquid crystal is changed into a pattern so that the optical properties are partially different, can be used for pattern design and refractive index. Various applications are expected by controlling the distribution and the like. For example, it is possible to realize an optically anisotropic body such as a diffraction grating, a layered waveguide structure, or a polarizing beam splitter made of an inorganic birefringent crystal at low cost.

  As an example of a method for producing an optical anisotropic body using the orientation of liquid crystal, a wave plate in which a concave / convex pattern of a diffraction grating is formed on a film by an optical anisotropic polymer obtained by polymerizing a polymerizable liquid crystal monomer And a method of manufacturing a component for an optical head having a function of a diffraction grating. (For example, refer to Patent Document 1) Specifically, after the polymerizable liquid crystal monomer is UV-cured using a photomask, the uneven pattern is prepared by elution and removal of the unpolymerized liquid crystal monomer. However, it is necessary to fill the uneven portion of the pattern with another optically anisotropic polymer, the production process is complicated, and it is difficult to adjust the phase difference.

As a method for forming a pattern without depending on the uneven pattern, there is a method using a photo-alignment film. For example, an alignment layer made of a photo-alignable polymer is selectively irradiated with polarized ultraviolet rays to form an alignment layer made of a photo-alignable polymer network (PPN) and in contact with the liquid crystal layer, and then the liquid crystal There has been proposed a method of obtaining an optical element having an anisotropic film of a liquid crystal monomer that is crosslinked so that the orientation of liquid crystal molecules is locally changed by applying a monomer and irradiating with ultraviolet rays (for example, patents) Reference 2). Since the alignment region is produced by ultraviolet irradiation, a fine pattern can be obtained.
However, when obtaining a diffraction grating that requires high resolution, such as a polarizing beam splitter, there is a possibility that pattern misalignment may occur in the thickness direction of the optical anisotropic body. A cell is prepared by aligning two substrates with a photo-alignment film having a liquid crystal alignment region so that the upper and lower patterns are aligned, and a polymerizable liquid crystal monomer is injected into the cell to align the polymerizable liquid crystal monomer. And (2) a method in which a polymerizable liquid crystal monomer is applied on a photo-alignment film having a plurality of different liquid crystal alignment ability regions and the polymerizable liquid crystal monomer is aligned.

On the other hand, the diffraction grating pattern is usually several tens of μm. Therefore, in the method (1), even when the alignment accuracy of the upper and lower alignment film patterns is 10% at the maximum, it is necessary to perform alignment of several μm one by one with a microscope. In addition, a special alignment device is required to do this industrially.
In the method (2), the alignment is not required. However, since one surface is in contact with air instead of the alignment film, alignment defects are generated, a good pattern is difficult to obtain, and an element with sufficient resolution is obtained. It was difficult.
Japanese Patent Laid-Open No. 9-50642 JP-A-6-289374

  The problem to be solved by the present invention is to provide a method for easily obtaining an optical anisotropic body having a partial structure free from alignment defects and having different optical anisotropy with high resolution.

  The inventors of the present invention have a plurality of regions in which one side of the substrate is substantially parallel and has liquid crystal alignment ability in different directions, and the other side of the substrate has substantially vertical liquid crystal alignment ability. A fine alignment pattern is formed by sandwiching a polymerizable liquid crystal material containing a liquid crystal compound having a polymerizable functional group between the substrates and polymerizing the liquid crystal material with active energy rays or heat in an aligned state. The present inventors have found that an optically anisotropic body free from alignment defects can be produced at low cost.

  That is, the present invention is an optical anisotropic body formed between two substrates, and one substrate has a plurality of alignment regions that are substantially parallel to the substrate and have different alignment directions. An optical anisotropic body having an orientation substantially perpendicular to the substrate is provided.

  The present invention also provides a substrate having a plurality of regions that are substantially parallel to the substrate and having liquid crystal alignment ability in different directions, and two substrates having liquid crystal alignment ability substantially perpendicular to the substrate. A polymerizable liquid crystal material containing a liquid crystal compound having a polymerizable functional group is sandwiched between substrates facing each other with the surface having the alignment ability inside, and the liquid crystal material is aligned and polymerized by active energy rays or heat. A method for producing an optical anisotropic body is provided.

The optical anisotropic body of the present invention is in a state in which alignment regulating ability is imparted to both surfaces of the element, and the substrate on one side has a plurality of regions that are substantially parallel and have liquid crystal orientation ability in different directions. The other side of the substrate has a liquid crystal compound having a polymerizable functional group in a state of having a substantially vertical liquid crystal alignment ability, so that a high-resolution, hybrid alignment in which the alignment direction is continuously changed without causing alignment defects or the like. The optically anisotropic body is obtained.
In addition, according to the manufacturing method of the present invention, it is not necessary to align the upper and lower alignment film patterns, so that a high-resolution optical anisotropic body can be manufactured inexpensively and easily.

The optical anisotropic body of the present invention includes a substrate (hereinafter abbreviated as substrate (A)) having a plurality of regions substantially parallel to the substrate and having liquid crystal alignment ability in different directions, and substantially perpendicular to the substrate. A liquid crystal compound having a polymerizable functional group (hereinafter, referred to as a substrate having a liquid crystal alignment ability) sandwiched between the substrates having the liquid crystal alignment ability (hereinafter, abbreviated as substrate (B)) with the surface having the liquid crystal alignment ability facing inside. Abbreviated as a polymerizable liquid crystal compound).
Hereinafter, “a plurality of regions having liquid crystal alignment ability in different directions” may be abbreviated as “pattern alignment region”.

  The material of the substrate is not particularly limited as long as it is substantially transparent, and glass, ceramics, plastics and the like can be used. As a plastic substrate, cellulose derivatives such as cellulose, triacetyl cellulose, diacetyl cellulose, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene and polyethylene, polycarbonate, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, nylon, Polystyrene, polyacrylate, polymethyl methacrylate, polyether sulfone, polyarylate and the like can be used.

(Substrate (A))
The substrate (A) is a substrate having a plurality of regions that are substantially parallel to the substrate and have liquid crystal alignment ability in different directions. The term “substantially parallel” as used herein refers to a state in which the molecular major axis of the liquid crystal molecules is in a plane parallel to the substrate surface or has an angle (tilt angle) of 20 ° or less with respect to the substrate surface. .
Examples of the substrate (A) include a glass substrate or a plastic substrate with an alignment film produced by a rubbing method, oblique deposition, an ion beam method, an LB method, a photo-alignment method, or the like. Among these, a substrate with an alignment film (hereinafter referred to as a photo-alignment film) made of a photo-alignable polymer is preferable because a pattern alignment region can be easily obtained with a photomask or the like.

  The photo-alignment film contains a dichroic dye such as an azo dye, a polymer having a structure capable of photoisomerization and photodimerization such as azobenzene, cinnamic acid ester, coumarin and chalcone, and a photoreactive compound such as polyimide. The composition to be obtained (hereinafter abbreviated as a composition for photo-alignment film) is applied on a substrate and irradiated with non-polarized light from an oblique direction with respect to polarized light or an alignment film surface. Among them, a composition containing a dichroic dye derivative is preferable, and a pattern alignment region can be most easily obtained with a photomask, and therefore a composition containing an azobenzene derivative is most preferable. A photo-alignment film made of an azobenzene derivative can be re-orientated even after it is once aligned with light, unlike other alignment films that involve generation or decomposition of chemical bonds accompanying light irradiation. Therefore, once the entire film is oriented in a specific direction, only a portion irradiated with light can be oriented in another direction using a photomask, so that a pattern orientation region can be obtained easily and accurately. Can do.

  As the azobenzene derivative, for example, a compound described in JP-A No. 2002-250924 or a compound described in SID′01 Digest, 1170 (2001) can be used. These compounds can be used in combination of several kinds.

  These azobenzene derivatives can be dissolved in an appropriate good solvent and applied to the substrate by spin coating, extrusion, gravure coating, die coating, bar coating, applicator and other application methods and flexographic printing methods. Apply on top. The solvent is not particularly limited, but the coating property of the compound for photo-alignment film on a substrate such as glass is good and a uniform film can be obtained. Therefore, N-methylpyrrolidone, butyl cellosolve, gamma-butyrolactone, dimethyl Formamide and the like are particularly preferable.

In order to impart the liquid crystal alignment ability to the photo-alignment film, linearly polarized light or elliptically polarized light having a wavelength that can be absorbed by the photoreactive compound contained in the composition for photo-alignment film is the substrate opposite to the alignment film surface or the alignment film surface. From the side, the alignment light is irradiated perpendicularly to the surface or from an oblique direction, or from the oblique direction to the alignment film surface. The angle when irradiating from an oblique direction is preferably in the range of 10 ° to 80 °, particularly preferably in the range of 30 ° to 60 ° with respect to the substrate surface. For pattern alignment, for example, a photomask is placed on a substrate on which a photo-alignment film is formed, and the entire surface is irradiated with polarized light or non-polarized light, and liquid crystal alignment capability is given to the exposed portion in a pattern. By repeating this a plurality of times as necessary, a pattern alignment region can be obtained.
Alternatively, the pattern alignment region can also be obtained by once aligning the entire film in a specific direction and then aligning only the portion irradiated with light using a photomask in another direction. For example, the entire surface of the photo-alignment film is irradiated with polarized light or non-polarized light from an oblique direction to give a liquid crystal alignment ability in one direction within the substrate surface, and then a photomask is overlaid on the alignment film surface for the first irradiation. By irradiating polarized light having a different polarization plane direction, it is possible to obtain a liquid crystal alignment ability in a direction different from the initial direction in a pattern.
There is no particular limitation on the shape of the pattern, and various patterns can be formed according to the purpose. For example, a pattern in which alignment regions are arranged alternately in a rectangular shape, a pattern in which alignment regions are aligned in a lattice shape, or a pattern in a pattern shape can also be formed. In the case of a pattern in which alignment regions are alternately arranged in a rectangular shape, the obtained optical anisotropic body functions as a diffraction grating.

The light for imparting liquid crystal alignment ability to the photo-alignment film may be light in a wavelength region that can be absorbed by a photoreactive compound such as an azobenzene derivative contained in the composition for photo-alignment film. For example, when an azobenzene derivative is used, ultraviolet light or visible light in a wavelength range of 350 to 500 nm corresponding to a strong absorption band due to the π → π ^* transition of azobenzene is particularly preferable. Examples of the light source for irradiation light include a xenon lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and an ultraviolet laser. In particular, since an ultra-high pressure mercury lamp is almost a point light source, it is particularly preferable because it is easy to obtain parallel light. Linearly polarized light can be obtained by passing light from the light source through a polarizing filter or a polarizing prism.

  When the photo-alignment film has a polymerizable functional group, a photopolymerization initiator or a thermal polymerization initiator described later is added to the composition for photo-alignment film, and application to the substrate and irradiation with light are performed. After light irradiation by a photomask, photopolymerization by light irradiation or thermal polymerization is performed by heating. However, thermal polymerization is preferable because there is a risk of damaging the alignment obtained by the light irradiation.

(Substrate (B))
The substrate (B) is a substrate having a liquid crystal alignment ability substantially perpendicular to the substrate. The term “substantially perpendicular” as used herein refers to a state in which the molecular long axis of the liquid crystal molecules is perpendicular to the substrate surface or has an angle (tilt angle) of 10 ° or less with respect to the normal to the substrate surface.
The vertical alignment film used in the present invention may be any film as long as it has a function of aligning the molecular axes of liquid crystal molecules substantially vertically by providing it as a coating film on the substrate. Specifically, for example, a composition for a silane coupling-based vertical alignment film such as lecithin, a silane-based surfactant, a titanate-based surfactant, a pyridinium salt-based polymer surfactant, and n-octadecyltriethoxysilane, Examples thereof include a composition for a polyimide-based vertical alignment film such as a soluble polyimide having a chain alkyl group or an alicyclic structure in the side chain, or a polyamic acid having a long chain alkyl group or an alicyclic structure in the side chain. In the present invention, as the composition for the vertical alignment film, the polyimide vertical alignment film composition “JALS-2021” and “JALS-204” manufactured by GS Co., Ltd., “ Commercial products such as “RN-1517” and “SE-1211” can be used as they are.

The vertical alignment film can be obtained by, for example, dissolving in an organic solvent so that the nonvolatile content concentration is about 1%, coating the substrate by a method such as spin coating, and then removing the organic solvent. Since the surface of the vertical alignment film is hydrophobic, the molecular axes of the liquid crystal molecules can be aligned substantially vertically. Among them, a polyimide-based composition for a vertical alignment film having a nonpolar long-chain alkyl group or an alicyclic structure is particularly preferable because it can be easily applied to a substrate and a vertical alignment film having excellent heat resistance can be obtained. .
The substrate (B) does not require pattern alignment but performs substantially vertical alignment that is uniform over the entire substrate, and does not require alignment with the pattern alignment region of the substrate (A).

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound used in the present invention is not particularly limited as long as it is a compound having a polymerizable functional group that exhibits liquid crystallinity alone or in a composition with another liquid crystal compound. For example, Handbook of Liquid Crystals (D. Demus, J. W. Goodbye, GW Gray, H. W. Spiss, V. Vill, edited by Wiley-VCH, 1998), Quarterly Chemical Review. 22, Liquid Crystal Chemistry (Edited by Chemical Society of Japan, 1994), or JP-A-7-294735, JP-A-8-3111, JP-A-8-29618, JP-A-11-80090, 1,4-phenylene group, 1,4-cyclohexene, as described in Kaihei 11-148079, JP-A 2000-178233, JP-A 2002-308831, and JP-A 2002-145830. A rod-like polymerizable liquid crystal compound having a rigid site called mesogen in which a plurality of structures such as a sylene group are connected and a polymerizable functional group such as a (meth) acryloyl group, a vinyloxy group, and an epoxy group, or, for example, Handbook of Liquid Crystals (D. Demus, J. W. Goodby, GW Gray, H. et al. W. Spiess, edited by V. Vill, published by Wiley-VCH, 1998), Quarterly Chemical Review No. 22. Liquid crystal chemistry (edited by Chemical Society of Japan, 1994) and discotic polymerizable compounds described in JP-A-07-146409. Among these, a rod-like liquid crystal compound having a polymerizable group is preferable because it can easily produce a liquid crystal having a temperature range around room temperature.

(Photopolymerization initiator)
When polymerizing the polymerizable liquid crystal compound, it is preferable to blend a known and commonly used photopolymerization initiator or thermal polymerization initiator.
Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone (“Irgacure 184” manufactured by Ciba Specialty Chemicals), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one ( “Darocur 1116” manufactured by Merck & Co.), 2-methyl-1-[(methylthio) phenyl] -2-morpholinopropane-1 (“Irgacure 907” manufactured by Ciba Specialty Chemicals), benzylmethylketal ( “Irgacure 651” manufactured by Ciba Specialty Chemicals). Mixture of 2,4-diethylthioxanthone (“Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.) and ethyl p-dimethylaminobenzoate (“Kayacure EPA” manufactured by Nippon Kayaku Co., Ltd.), acylphosphine oxide (“Lucirin” manufactured by BASF TPO "), and the like. On the other hand, examples of the thermal polymerization initiator include organic peroxides such as benzoyl peroxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-butyl peroxybenzoate, and methyl ethyl ketone peroxide. Azonitrile compounds such as 2′-azobisisobutyronitrile, azoamidin compounds such as 2,2′-azobis (2-methyl-N-phenylpropion-amidin) dihydrochloride, 2,2′azobis {2-methyl- Use azoamide compounds such as N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, alkylazo compounds such as 2,2′azobis (2,4,4-trimethylpentane), and the like. Can do. The amount of these polymerization initiators used is preferably 10% by mass or less, particularly preferably 0.5 to 5% by mass, based on the composition. (Hereinafter, a composition containing the polymerizable liquid crystal compound and a polymerization initiator is abbreviated as a polymerizable liquid crystal composition.)

(Optical anisotropic body manufacturing method)
In the optical anisotropic body of the present invention, for example, the substrate (A) and the substrate (B) are fixed to each other using a spacer and a sealant with each substrate having a surface having liquid crystal alignment ability inside. A cell is formed by bonding with a gap, and a method of injecting a polymerizable liquid crystal composition into the cell, or dropping a polymerizable liquid crystal composition on the substrate (A), and then the substrate (B) from above. Obtained by sandwiching the polymerizable liquid crystal composition between both substrates and then polymerizing the polymerizable liquid crystal composition in a state where the polymerizable liquid crystal composition is oriented. .
The interval between the substrates varies depending on the desired phase difference of the optical anisotropic body, but it is preferable to be approximately 2 μm to 20 μm. An optical anisotropic body having a desired phase difference can be obtained by adjusting the distance between the substrates, that is, the thickness of the polymer of the resulting polymerizable liquid crystal composition.
Examples of the spacer include glass particles, plastic particles, alumina particles, and a photoresist material. Thereafter, a sealing agent such as an epoxy-based thermosetting composition is screen-printed on the substrates in a form provided with an inlet for the polymerizable liquid crystal composition, the substrates are bonded together, and heated to thermally cure the sealing agent. .

Examples of the method for polymerizing and fixing the aligned polymerizable liquid crystal composition include a method of irradiating active energy rays and a thermal polymerization method, but the reaction proceeds at room temperature without requiring heating. A method of irradiating active energy rays is preferable, and among them, a method of irradiating light such as ultraviolet rays is preferable because of easy operation. The temperature at the time of irradiation is preferably set to 25 ° C. or less as much as possible in order to avoid the induction of thermal polymerization of the polymerizable liquid crystal composition so that the polymerizable liquid crystal composition can maintain the liquid crystal phase. The liquid crystal composition usually has a liquid crystal phase in the range from the C (solid phase) -N (nematic) transition temperature (hereinafter abbreviated as C-N transition temperature) to the NI transition temperature in the temperature rising process. Indicates. On the other hand, in the temperature lowering process, a non-equilibrium state is taken thermodynamically, so that the liquid crystal state may be maintained without being solidified even at a temperature lower than the CN transition temperature. This state is called a supercooled state. In the present invention, the liquid crystal composition in a supercooled state is also included in the state in which the liquid crystal phase is retained. The ultraviolet irradiation intensity is preferably in the range of 1 W / m ^{2 to} 10 kW / m ² . In particular, a range of 10 W / m ^{2 to 2} kW / m ² is preferable. When the ultraviolet intensity is less than 1 W / m ² , it takes a lot of time to complete the polymerization. On the other hand, when the strength exceeds ² kW / m ² , liquid crystal molecules in the polymerizable liquid crystal composition tend to be photodegraded, or a large amount of polymerization heat is generated to increase the temperature during polymerization. The parameter may change, and the retardation of the film after polymerization may be distorted.

  The optical anisotropic body of the present invention may be used with a substrate attached, but it can also be used as a film by peeling off one or both substrates.

Hereinafter, the present invention will be described more specifically with reference to examples.
(Preparation of polymerizable liquid crystal composition)
A liquid crystal composition comprising 20 parts by mass of the compound represented by the formula (a), 40 parts by mass of the compound represented by the formula (b), and 40 parts by mass of the compound represented by the formula (c) was prepared. The mixture was filtered through a 1 μm filter to obtain a polymerizable liquid crystal composition.
The polymerizable liquid crystal composition had a CN transition temperature of 31 ° C. and an NI transition temperature of 48 ° C. When the temperature of the liquid crystal composition was lowered from 48 ° C., the liquid crystal composition was supercooled at 31 ° C. or lower and exhibited a liquid crystal phase even at 25 ° C.

(Adjustment of composition for photo-alignment film)
The compound represented by the formula (d) was dissolved in N, N-dimethylformamide (DMF) to obtain a 1% by weight solid content solution. This solution was filtered through a filter having a pore diameter of 0.5 μm to obtain a composition for a photo-alignment film.

（ｄ）

(D)

(Tilt angle measurement)
Tilt angles were measured for the alignment film-attached substrates (A-1) to (A-3), (B-1), and (B-2) described later. The measurement was performed by injecting a polymerizable liquid crystal composition into a liquid crystal cell (cell gap 5 μm) produced by arranging two substrates of the same type in an anti-parallel state, and measured by a crystal rotation method.

(Example 1)
The composition for photo-alignment film was uniformly applied on a glass substrate by a spin coating method, and dried at 100 ° C. for 1 minute. The surface of the coating film thus obtained was subjected to an ultrahigh pressure mercury lamp as a light source, and non-polarized ultraviolet light that was made substantially parallel using a bandpass filter and a collimator mirror near 365 nm was 45 ° with respect to the substrate surface. A light amount of 5 J / cm ² was irradiated from an angle.
Next, a photomask having a rectangular slit with a period of 20 μm is overlaid on the surface of the photo-aligned film irradiated with light, forming an angle of 90 ° with the incident surface of the first irradiated light and 45 ° with respect to the substrate surface. With a photo-alignment film having a substantially parallel orientation, in which a rectangular alignment region in which the in-plane orientation direction of the photo-alignment film differs by 90 ° is alternately arranged by irradiating a light amount of 5 J / cm ² from the angle of A substrate (A-1) was produced. The tilt angle of the substrate (A-1) was 5 °.
On another substrate, a polyimide-based vertical alignment film composition “JALS-2021” (manufactured by JSR Co., Ltd.) is applied onto a glass substrate by spin coating, and baked at 190 ° C. for 1.5 hours. A substrate with a vertical alignment film (B-1) was produced. The tilt angle of the substrate (B-1) was 0 ° with respect to the normal to the substrate surface.
A photo-curable adhesive containing styrene beads having a diameter of 5 μm is applied to the outer edge of the surface of the substrate (A-1) where the photo-alignment film is formed so that the liquid crystal injection port remains, and the substrate (B-1 ) Were superimposed and pressure-bonded so that the alignment film surfaces faced each other, and the adhesive was cured by irradiating with ultraviolet rays to form a cell.

Next, a composition obtained by adding a photopolymerization initiator “Irgacure 907” (manufactured by Ciba Specialty Chemicals Co., Ltd.) to the polymerizable liquid crystal composition so as to have a mass ratio of 98: 2 is applied to the cell. Injection was performed by an injection method. Using an ultra-high pressure mercury lamp, ultraviolet light having an intensity of 0.25 W / cm ² was irradiated for 4 seconds from a direction perpendicular to the substrate surface, and the injected polymerizable liquid crystal composition was subjected to a photopolymerization reaction, and optical properties were different. A rectangular parallelepiped (1) was produced.
When a He—Ne laser (633 nm) that has passed through a polarizing plate is incident perpendicularly to the substrate surface and the polarization vibration direction is parallel to one orientation direction of the rectangular pattern, Raman-Nath scattering is exhibited. , Up to ± 5th order diffraction peaks were observed, confirming that it functions as a diffraction grating. The laser beam transmittance was 98.5%.
When the optical anisotropic body (1) was observed with a polarizing microscope, a rectangular bright and dark pattern was clearly observed, and no disturbance of the pattern due to alignment defects of the liquid crystal was observed.

(Comparative Example 1)
In Example 1, an optical anisotropic body (2) was prepared in the same manner as in Example 1 except that a glass substrate (B-2) without an alignment film was used instead of the substrate (B-1) with a vertical alignment film. did. When a He-Ne laser (633 nm) that has passed through a polarizing plate is incident perpendicularly to the substrate surface and the polarization vibration direction is parallel to one of the orientation directions of the rectangular pattern, Raman-Nath scattering occurs. It was observed that up to ± 5th order diffraction peaks, confirming that it functions as a diffraction grating. However, the laser beam transmittance was 94.0%.
When this optical anisotropic body (2) is observed with a polarizing microscope, a rectangular light and dark pattern is observed, but there are many orientation defects, and light transmittance is reduced due to light scattering due to this. I understood.

(Comparative Example 2)
The composition for photo-alignment film was uniformly applied to two square substrates having a side of 20 mm by a spin coating method, and dried at 100 ° C. for 1 minute.
On one of these substrates, the same ultraviolet ray as in Example 1 was applied to the surface of the coating film in a plane perpendicular to the substrate surface and forming an angle of + 45 ° with respect to one side of the substrate, and with respect to the substrate surface. The light was irradiated at a light amount of 5 J / cm ² from a direction of 45 °. Next, it has a rectangular slit with a period of 20 μm, and a photomask having the same shape as that of the substrate is superimposed on the surface of the photo-aligned film that has been irradiated with the light so that it is aligned with the substrate. By irradiating with a light amount of 5 J / cm ² from a direction of 45 ° with respect to the substrate surface and an angle of 90 ° with the incident surface, the photo-alignment film has a rectangular shape whose in-plane alignment direction is different by 90 ° A substrate with a photo-alignment film (A-2) subjected to a patterning process in which alignment regions were alternately arranged was produced. The tilt angle of the substrate (A-2) was 5 °.
On the other substrate, the same ultraviolet rays are applied at a rate of 5 J / cm from the direction perpendicular to the substrate surface and at an angle of −45 ° to one side of the substrate and from the direction of 45 ° to the substrate surface. Irradiated with a light quantity of ² . Next, it has a rectangular slit with a period of 20 μm, and a photomask having the same shape as that of the substrate is superimposed on the surface of the photo-aligned film that has been irradiated with the light so that it is aligned with the substrate. By irradiating with a light amount of 5 J / cm ² from a direction of 45 ° with respect to the substrate surface and an angle of 90 ° with the incident surface, the photo-alignment film has a rectangular shape whose in-plane alignment direction is different by 90 ° A substrate with a photo-alignment film (A-3) subjected to a patterning process in which alignment regions were alternately arranged was produced. The tilt angle of the substrate (A-3) was 5 °.
A photocurable adhesive containing styrene beads having a diameter of 5 μm is applied to the outer edge of the surface of the substrate (A-2) where the photo-alignment film is formed so that the liquid crystal injection port remains, and the substrate (A-3) is applied to this. ) Were aligned and pressure-bonded with the alignment film surfaces facing each other while precisely aligning the sides of the substrate, and the adhesive was cured by irradiating ultraviolet rays.

Next, the polymerizable liquid crystal composition was injected into the gap between the glass substrates bonded together as described above by a vacuum injection method. Using an ultra-high pressure mercury lamp, ultraviolet light having an intensity of 0.25 W / cm ² is irradiated for 4 seconds from a direction perpendicular to the substrate surface to carry out a photopolymerization reaction of the polymerizable liquid crystal composition, thereby producing an optical anisotropic body. (3) was produced.
When this optical anisotropic body (3) was observed with a polarizing microscope, pattern disturbance due to alignment defects in the liquid crystal was not observed, but a deviation in the alignment patterns of the upper and lower substrates of about 10 μm was observed.
When a He-Ne laser (633 nm) that has passed through a polarizing plate is incident perpendicularly to the substrate surface and the polarization oscillation direction is parallel to one orientation direction of the rectangular pattern, the light diffraction pattern is almost Not observed.

(Comparative Example 3)
In the process of superimposing the substrate (A-3) on the substrate (A-2) of Comparative Example 2, the relative positions of the upper and lower substrates are finely adjusted while observing with a polarizing microscope, and the patterns of the upper and lower substrates match with accuracy within 1 μm. After confirming this, an optically anisotropic body (4) was produced in the same manner as in Comparative Example 2 except that these were pressure-bonded.
When a He—Ne laser (633 nm) that has passed through a polarizing plate is incident perpendicularly to the substrate surface and the polarization oscillation direction is parallel to one orientation direction of the rectangular pattern, Raman-Nath scattering is exhibited. , Up to ± 5th order diffraction peaks were observed, confirming that it functions as a diffraction grating. The laser beam transmittance was 98.5%.
When the optical anisotropic body (4) was observed with a polarizing microscope, a rectangular bright and dark pattern was clearly observed, and no disorder of the pattern due to alignment defects of the liquid crystal was observed.
However, this method requires fine adjustment of the relative positions of the upper and lower substrates with a polarizing microscope, and is not suitable for mass production.

  The optical anisotropic body of the present invention can be applied to a diffraction grating, a layered waveguide structure, a polarizing beam splitter, etc., and particularly applicable to a wave plate or a diffraction grating in an optical head device such as a CD, DVD, or MO. It is.

It is the top view and side sectional view which showed typically the specific aspect of the optical anisotropic body of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Alignment direction of polymerizable liquid crystal near the photo-alignment film subjected to patterning treatment of substrate (C) 2 Substrate 3 Photo-alignment film subjected to patterning alignment treatment 4 Vertical alignment film 5 Polymerized polymerizable liquid crystal layer

Claims (5)

An optical anisotropic body formed between two substrates, wherein one substrate has a plurality of alignment regions that are substantially parallel to the substrate and have different alignment directions, and the other substrate An optical anisotropic body having an orientation substantially perpendicular to a substrate. 2. The optical anisotropic body according to claim 1, wherein the plurality of alignment regions having different alignment directions of the optical anisotropic body are formed by a photo alignment film, and the substantially vertical alignment is formed by a vertical alignment film. The optical anisotropic body according to claim 2, wherein the photo-alignment film is made of a composition containing an azobenzene derivative. A substrate having a plurality of regions substantially parallel to the substrate and having a liquid crystal alignment ability in different directions, and a substrate having a liquid crystal alignment ability substantially perpendicular to the substrate, with the surface having the liquid crystal alignment ability inward. An optical anisotropy characterized by sandwiching a polymerizable liquid crystal material containing a liquid crystal compound having a polymerizable functional group between opposed substrates and polymerizing the liquid crystal material with active energy rays or heat in an aligned state. Body manufacturing method. A substrate having a plurality of regions substantially parallel to the substrate and having a liquid crystal alignment ability in different directions is applied to a photo-alignment film formed on the substrate through a photomask from a direction oblique to the polarization or alignment film surface. The method for producing an optical anisotropic body according to claim 4, wherein the substrate is a substrate in which a plurality of liquid crystal alignment regions are generated in a photo-alignment film by irradiating polarized light.

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