JP4756342B2 - Optical film, elliptically polarizing plate, circularly polarizing plate, liquid crystal display element, and method for producing the optical film - Google Patents

Description

  The present invention relates to an optical film, an elliptically polarizing plate, a circularly polarizing plate, and a liquid crystal display device using these optical films, in which an optically anisotropic layer obtained by polymerizing a polymerizable liquid crystal composition is aligned, And a method for producing the optical film.

  A circularly polarizing plate or an elliptically polarizing plate is a combination of a polarizing plate and an optical film having an appropriate retardation, which is indispensable for the principle of operation of the display, and for the purpose of solving the problem of visual field characteristics. It is used as one member. These visual circumstances include LCD type (for example, STN type LCD, TFT-LCD, IPS (In-Plane Switching In-Plane Switching) type LCD, FLC (Ferroelectric Liquid Crystal Ferroelectric Liquid Crystal) type LCD, OCB (Optically Compensated Bend) type LCD, VA (Vertically Aligned) type LCD, ECB (Electrically Controlled Birefringence Electrically Beverly Hiddle Type HB) Al Adapted to each method because it differs depending on the positional relationship between the light source and the liquid crystal such as a GNED type LCD, GH (Guest Host Guest-Host) type LCD, transmissive type, reflective type, and transflective type. A circularly or elliptically polarizing plate is required.

For example, in a STN type liquid crystal display device (LCD), the display color and display contrast change depending on the viewing direction in the TFT-LCD in order to eliminate the problem of coloring the screen due to the phase difference applied when the liquid crystal is transmitted. In order to eliminate such a problem, an elliptically polarizing plate combining a linearly polarizing plate and an optical film is used.
In addition, reflective, transflective, and micro-reflective LCDs that use external light as a light source use a circularly polarizing plate in which a quarter-wave plate is combined with a linear polarizing plate.
In addition, since a normal quarter wave plate has a phase difference of a quarter wavelength only at one wavelength, and a phase difference at other wavelengths is a value shifted from this, 1 / wave over the entire visible light range. For the purpose of functioning as a four-wave plate, a broadband circular polarizer or a combination of a linear polarizer and a broadband retardation film formed by laminating one or a plurality of half-wave plates and quarter-wave plates. A broadband elliptically polarizing plate in which a retardation film in which these retardation layers are laminated and a polarizing plate are combined has also been developed.

Usually, a circularly polarizing plate in which a polarizing plate and a quarter wavelength plate are combined is formed by superposing a polarizing plate and a quarter wavelength plate. At this time, they must be superposed so that the angle between the absorption axis of the polarizing plate and the slow axis of the quarter-wave plate exactly matches 45 °. Similarly, a broadband circularly polarizing plate in which a polarizing plate and a broadband retardation film formed by laminating a plurality of wave plates are combined, and the lamination angle with respect to the azimuth of each wave plate and the absorption axis of the wave plate and the polarizing plate It is necessary to strictly control the stacking angle.
When used in a liquid crystal display element, the angle formed between the optical axis of the wave plate and the alignment direction of the liquid crystal must be precisely as designed.

  Conventionally, a birefringent stretched film has been used for the retardation film, but in recent years, as a retardation film having more complicated optical properties, a polymerizable liquid crystal is applied on a substrate provided with an alignment film, An optical film that has been cured in a state where liquid crystal molecules are aligned has been developed. Specifically, a polymer film such as polyimide is provided on a substrate, a polymerizable liquid crystal is applied on an alignment film that is rubbed (rubbed) with a cloth or the like in one direction, and the liquid crystal molecules are rubbed in the rubbing direction. A phase difference film having optical properties that cannot be obtained with a stretched birefringent film can be obtained by combining the alignment direction of the alignment film and the alignment form of the polymerizable liquid crystal. It is done.

  However, the rubbing alignment film has a problem of causing scratches and dust during the rubbing process. Dust generation can be removed by washing or the like, but scratches cannot be removed. Therefore, the optical uniformity of the laminated liquid crystal film may be greatly impaired. In addition, in the manufacturing process using a rubbing type alignment film and a roll-like long film, the rubbing direction with respect to the film transport direction has a limit, so the slow axis of the retardation film remains the same as the long film. It is practically impossible to obtain a lamination angle. Therefore, in a normal manufacturing process, a rectangular film is cut out from a long film and laminated so as to have an appropriate lamination angle, or the cut film is laminated and laminated at an appropriate angle. Yes. Therefore, there is a problem in that an extremely complicated process is unavoidable, and the cut-out direction needs to be inclined with respect to the longitudinal direction of the long film. In addition, there is a problem in that the stacking accuracy with respect to the desired stacking angle obtained by the simulation or the like cannot be sufficiently obtained, and an optical film having an optical function as designed cannot be obtained.

  A photo-alignment film is known as an alignment film that is not rubbed. The photo-alignment method is one of alignment methods in which liquid crystal molecules can be aligned without rubbing, and the film formed on the substrate is irradiated with light, and liquid crystal alignment ability is generated in the film in a non-contact manner. be able to. The alignment can be controlled by the direction of light, and unlike the rubbing method, it has the characteristic that there is no possibility of scratches or dust generation in principle, so a retardation film using a liquid crystal having a polymerizable group is created. In the above, the degree of freedom in controlling the alignment state is increased, and there is no light leakage due to scratches, and a uniform film can be formed.

  For example, after applying a photo-alignment polymerizable composition containing a dichroic dye having two or more polymerizable groups in one molecule on a substrate, irradiating polarized light to impart a photo-alignment function, heating Alternatively, a photo-alignment film obtained by irradiating light to polymerize a polymerizable group, or a polymerizable substance such as 4, polyvinyl cinnamate (see, for example, Patent Document 1) is applied on a substrate, and is anisotropic. A photo-alignment film obtained by irradiating and reacting with light is known (for example, see Patent Document 2). An optical film made of a photo-alignment film made of polyvinyl cinnamate and a polymerizable liquid crystal described in Patent Document 2 is also known (see, for example, Patent Documents 3 and 4). However, the optical films obtained by using these photo-alignment films have a problem that the interface between the photo-alignment film and the polymerizable liquid crystal layer is peeled off, resulting in poor durability.

  As an optical film having excellent durability, a polymer coating film having a polymerizable group provided on a substrate is rubbed, and a discotic liquid crystal having a polymerizable group is applied thereon, and a rubbing alignment film and a discotic liquid crystal are applied. There is known an optical compensation sheet excellent in durability, which is obtained by chemically bonding an optically anisotropic layer made of However, since the method uses a rubbing alignment film, the problem still arising from the rubbing alignment film cannot be solved. The optical compensation sheet relates to a vertical alignment film in which the diameter direction of the discotic liquid crystal molecules is aligned in a direction perpendicular to the substrate, and by introducing a long alkyl chain, an aliphatic chain, or the like. Since the surface energy of the alignment film surface is lowered, liquid crystal molecules tend to aggregate on the surface of the vertical alignment film, and there is a problem that it is difficult to stack in a thin film state.

On the other hand, as a problem peculiar to the laminated film, for example, interface reflection may occur at the boundary between the liquid crystal alignment film and the polymerizable liquid crystal layer, and there may be a problem that a desired transmitted light intensity cannot be obtained. This is not a problem in the case of an optical film consisting only of an alignment film and a polymerizable liquid crystal layer (that is, having one laminated interface), but the one or a plurality of half-wave plates and 1 / A broadband circularly polarizing plate combining a broadband retardation film formed by laminating a four-wavelength plate and a linear polarizing plate, a broadband elliptical polarizing plate combining a retardation film stacked with a plurality of retardation layers and a polarizing plate, etc. In such an optical film laminated in multiple layers, there are a large number of laminated interfaces, which is a major cause of a decrease in transmitted light intensity. As a result, the contrast required for the display is lowered, and in particular, the transmitted light intensity in the direction inclined from the normal to the screen is lowered.
JP 2002-250924 A JP 07-138308 A Japanese Patent Laid-Open No. 06-289374 Japanese Patent Laid-Open No. 08-15681 JP 09-152509 A

An optical film having various functions can be created by laminating two optically anisotropic layers. However, in order to design a precise optical film, the angle formed by the two optical delay axes must be precise. Must be as designed. In the case of use in a liquid crystal display element, the angle formed by the optical axis of the optical film and the alignment direction of the liquid crystal must be precisely as designed.
However, as described above, the conventional optical film cannot sufficiently obtain the above lamination accuracy, and an optical film having an optical function as designed has not been obtained. In addition, an optical film in which a polymer layer obtained by applying and polymerizing a polymerizable liquid crystal on a liquid crystal alignment film is insufficient in the adhesiveness between the liquid crystal alignment film layer and the cured polymer layer, and the manufacturing process. There was a problem that peeling occurred.

The problem to be solved by the present invention is:
1. There is no need for complicated processes such as film cutting and pasting,
2. Accurately laminated with the positional relationship (lamination angle) of the optical axis as designed,
3. Peeling between layers hardly occurs,
An optical film formed by laminating a plurality of optically anisotropic layers (that is, wave plates), a circularly polarizing plate and an elliptically polarizing plate formed by laminating the optical film and a polarizing plate, and a liquid crystal display device using these optical films And it is providing the manufacturing method of this optical film.

The inventors
1. By using a photo-alignment film, a polymerizable liquid crystal layer aligned in an arbitrary alignment direction can be formed. By repeating this process, a multilayer film having a desired slow axis stacking angle can be easily obtained. What can be done 2. Since the alignment axis of the photo-alignment film can be determined by the light irradiation direction, it can be stacked at a precise stacking angle as designed. The present inventors have found that an optical film having a strong interlayer adhesive force that hardly peels off can be obtained by covalently bonding between the photo-alignment layer and the polymerizable liquid crystal layer, and the present invention has been completed. Both the photo-alignment film layer and the polymer layer can be obtained by a coating method, and the orientation direction can be controlled in a non-contact manner depending on the direction of irradiation light, so there is no need for complicated steps such as cutting out and pasting the film. A polymerizable liquid crystal layer aligned in the alignment direction can be formed.
Specifically, when a photoalignable polymerizable composition containing a photoalignable group and a compound having a polymerizable group is applied and dried (step a), the polarized light or the substrate can be absorbed by the photoalignable group. When the liquid crystal alignment ability is imparted by irradiating non-polarized light from an oblique direction (step b), a polymerizable liquid crystal composition layer having a polymerizable group is formed on the layer (step c), The step (I) (hereinafter abbreviated as step (I)), in which the two layers are polymerized between the molecules of both layers simultaneously with the progress of curing of both layers by active energy rays or heat (step d). ) Is repeated a plurality of times, it is possible to easily obtain an optical film having a multilayer structure having a strictly controlled laminating angle of the slow axis.

  That is, the present invention comprises a photo-alignment layer (A) having a liquid crystal alignment ability produced by light irradiation and a liquid crystal compound having a polymerizable group, and polymerized in a state of being aligned by the photo-alignment layer (A). Provided is an optical film in which a plurality of optically anisotropic layers in which the resulting polymer layer (B) is covalently bonded are laminated.

  The present invention also provides an elliptically polarizing plate having the optical film described above and a polarizing plate.

  The present invention also provides a circularly polarizing plate having the optical film described above and a polarizing plate.

  Moreover, this invention provides the liquid crystal display element using the said optical film.

  Further, the present invention is a method for producing the optical film described above, wherein the compound having a photoalignable group and a polymerizable group, or a photoalignable polymerizable compound comprising a compound having a photoalignable group and a polymerizable compound. Applying and drying the composition to form a photo-alignable polymerizable composition layer a, and applying a liquid crystal by irradiating polarized light having a wavelength that can be absorbed by the photo-alignable group or non-polarized light from an oblique direction to the substrate Step b for providing alignment ability, Step c for forming a polymerizable liquid crystal composition layer containing a polymerizable liquid crystal composition containing a liquid crystal compound having a polymerizable group on the layer, and two laminated layers, Provided is a method for producing an optical film in which the step (I) having the step d of polymerizing the molecules of both layers simultaneously with the progress of curing of both layers by active energy rays or heat is repeated a plurality of times.

The optical film of the present invention is a laminated film excellent in durability, which is precisely laminated with a positional relationship (lamination angle) of optical axes as designed. A circularly polarizing plate or an elliptically polarizing plate formed by laminating the optical film of the present invention and a polarizing plate can be easily obtained without the need for strict alignment or complicated processes. Unlike optical pasting methods, optical films, circularly polarizing plates, and elliptically polarizing plates do not generate materials that are wasted during the manufacturing process.
In the present invention, further, as a compound having a photo-alignable group and a polymerizable group, which is a material of the photo-alignment layer (A) in which the liquid crystal alignment ability is generated by light irradiation in the optical film of the present invention, or One of the problems of laminated optical films is by selecting a low molecular weight raw material as a composition comprising a compound having a photo-alignable group and no polymerizable group and a general-purpose polymerizable compound. The problem of “having high transmitted light intensity” can also be solved. Since the low molecular weight raw material is slightly inferior in smoothness, it is difficult to cause a boundary with the upper layer. That is, it is possible to obtain an optically excellent optical film in which interface reflection does not occur at the boundary between the photo-alignment layer (A) and the polymer layer (B). This is particularly useful when an optical film is obtained by laminating many layers such as a broadband circularly polarizing plate and a broadband elliptically polarizing plate.
The optical film, circularly polarizing plate, and elliptically polarizing plate of the present invention can all be obtained by a coating method, and the present optical film can be continuously bonded to a linearly polarizing film. Therefore, a complicated process such as cutting and pasting in which the angle is controlled as in the prior art is not necessary. Therefore, the present invention is applicable to a roll-to-roll method with high productivity using a long film.

(Optically anisotropic layer)
The optically anisotropic layer used in the present invention is composed of a photo-alignment layer (A) (hereinafter abbreviated as layer (A)) and a polymer layer (B) (hereinafter referred to as layer) having liquid crystal alignment ability produced by light irradiation. (Abbreviated as (B)). This is a compound having a photoalignable group and a polymerizable group (hereinafter abbreviated as compound (C)), or a compound having a photoalignable group and having no polymerizable group (hereinafter, compound (D). And a general-purpose polymerizable compound (hereinafter abbreviated as compound (E)), a photo-alignable polymerizable composition layer (hereinafter referred to as photo-alignable polymerizable). And a polymerizable liquid crystal composition layer containing a polymerizable liquid crystal composition containing a liquid crystal compound having a polymerizable group (hereinafter abbreviated as a polymerizable liquid crystal composition layer). Can be obtained by reacting both layers in a state where the liquid crystal compound having the polymerizable group is aligned. The photo-alignable polymerizable composition layer corresponds to the layer (A), and the polymerizable liquid crystal composition layer corresponds to the layer (B). Further, the optically anisotropic layer used in the present invention does not require that the layer (A) and the layer (B) are completely polymerized and cured, and the interface between the layer (A) and the layer (B) is shared. What is necessary is just to be couple | bonded by the coupling | bonding.
Specifically, a step of applying a photoalignable polymerizable composition layer containing a compound (C) or a compound (D) and a compound (E) and drying to form a photoalignable polymerizable composition layer a And a step b of giving a liquid crystal alignment ability by irradiating polarized light having a wavelength that can be absorbed by the photoalignable group or non-polarized light from an oblique direction to the substrate, and forming a polymerizable liquid crystal composition layer on the layer Step (I) (hereinafter referred to as Step (I)), and Step (d) in which the two layers thus laminated are subjected to curing of both layers by active energy rays or heat and simultaneously polymerize between the molecules of both layers. By using (abbreviated as I), an optically anisotropic layer is obtained. Moreover, an optical film in which a plurality of optically anisotropic layers are laminated is obtained by repeating step (I) a plurality of times. An example of the optical film of the present invention is shown in FIG. In FIG. 1, numerals 10, 11, 12, and 13 denote an optical film, a photo-alignment layer (A), a polymer layer (B), and an optically anisotropic layer, respectively.

(Layer (A) 11)
The layer (A) 11 contains a compound having a group (hereinafter abbreviated as a photo-alignment group) that generates liquid crystal alignment ability when irradiated with light, for example, a dichroic dye.
In the present invention, the photo-alignment group possessed by the compound (C) or the compound (D) is a molecular orientation induction or isomerization reaction (eg, azobenzene) due to the Weigert effect caused by photodichroism, which is caused by irradiation with light. Group), dimerization reaction (example: cinnamoyl group), photocrosslinking reaction (example: benzophenone group), or photolysis reaction (example: polyimide group) To express. Among them, those utilizing molecular orientation induction or isomerization reaction, dimerization reaction, or photocrosslinking reaction due to the Weigert effect resulting from photodichroism are excellent in orientation and can easily align polymerizable liquid crystal compounds. This is preferable.
The photo-alignment group is not particularly limited, but among them, at least one double bond selected from the group consisting of C = C, C = N, N = N, and C = O (however, it forms two aromatic rings). A group having (excluding a heavy bond) is particularly preferably used.
In the present invention, the Weigert effect means that the orientation direction of a molecule having a transition moment changes so that the transition moment of the molecule is perpendicular to the polarization direction of incident light.

Examples of these photo-alignable groups include groups having a structure such as a polyene group, a stilbene group, a stilbazole group, a stilbazolium group, a cinnamoyl group, a hemithioindigo group, and a chalcone group. It is done. Examples of the group having a C═N bond include groups having a structure such as an aromatic Schiff base and an aromatic hydrazone. Examples of the group having an N═N bond include groups having a structure such as an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and those having a basic structure of azoxybenzene. Examples of the group having a C═O bond include groups having a structure such as a benzophenone group, a coumarin group, and an anthraquinone group. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, and a halogenated alkyl group.
Among them, an azobenzene group or anthraquinone group that exhibits photo-alignment by a photoisomerization reaction, or a benzophenone group, cinnamoyl group, chalcone group, or coumarin group that exhibits photo-orientation by a photodimerization reaction has a polarization necessary for photo-alignment. This is particularly preferable because the irradiation amount is small, and the obtained photo-alignment film has excellent thermal stability and stability over time. Of these, an azobenzene group is preferable.

  In the optically anisotropic layer 13 used in the present invention, the layer (A) 11 and the layer (B) 12 are bonded by a covalent bond. This is because a layered film of a photo-alignable polymerizable composition layer and a polymerizable liquid crystal composition layer is formed on a substrate, and the liquid crystal compound having the polymerizable group is aligned, and both layers are reacted. Can be obtained.

(Compounds (C) and (D))
Examples of the polymerizable group possessed by the compound (C) include (meth) acryloyl group, (meth) acryloyloxy group, (meth) acrylamide group, vinyl group, vinyloxy group, azide group, chloromethyl group, epoxy group, and maleimide. Group and the like. Among these, since photopolymerization and thermal polymerization are relatively easy, (meth) acryloyl group, (meth) acryloyloxy group, (meth) acrylamide group, vinyl group, vinyloxy group are preferable, (meth) acryloyl group, A (meth) acryloyloxy group or a (meth) acrylamide group is more preferable. Moreover, when it is a maleimide group, it can superpose | polymerize, without using a photoinitiator.

  These polymerizable groups may be directly bonded to the photoalignable group or may be bonded via a linking group such as an alkylene group or a phenylene group. The linking group may have an ester bond, an ether bond, an imide bond, an amide bond or a urethane bond. Examples of such a linking group include a methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, A linear alkylene group having 1 to 18 carbon atoms such as dodecamethylene group; 1-methylethylene group, 1-methyl-trimethylene group, 2-methyl-trimethylene group, 1-methyl-tetramethylene group, 2-methyl A branched alkylene group having 1 to 18 carbon atoms such as tetramethylene group, 1-methyl-pentamethylene group, 2-methyl-pentamethylene group, 3-methyl-pentamethylene group; phenylene such as p-phenylene group Groups: 2-methoxy-1 / 4-phenylene group, 3-methoxy-1 / 4-phenylene group, 2-eth Linear or branched having 1 to 18 carbon atoms such as cis-1 / 4-phenylene group, 3-ethoxy-1 / 4-phenylene group, 2,3,5-trimethoxy-1 / 4-phenylene group, etc. Examples include an alkoxyphenylene group having an alkoxyl group.

The molecular weight of the compound (C) or the compound (D) is not particularly limited, but is usually 1 × 10 ² to 1 × 10 ⁶ in terms of mass average molecular weight. However, if the molecular weight is too high, the photo-alignment group becomes difficult to move in the system, and the sensitivity to light tends to decrease. In general, the higher the polymer, the better the film formability and the smoother surface coating film is obtained. In the present invention, when the surface of the layer (A) 11 is very smooth, There may be borders and optical effects. Accordingly, the molecular weight is more preferably in the range of 1 × 10 ² to 1 × 10 ⁵ , and still more preferably in the range of 1 × 10 ^{2 to} 5 × 10 ³ .

  Specifically, the compound (C) is preferably a compound represented by the general formula (1).

In the formula, R ¹ and R ² are each independently a polymerization selected from the group consisting of (meth) acryloyl group, (meth) acryloyloxy group, (meth) acrylamide group, vinyl group, vinyloxy group, and maleimide group. Represents a sex group. Of these, a (meth) acryloyl group, a (meth) acryloyloxy group, or a (meth) acrylamide group is preferable because photopolymerization and thermal polymerization are relatively easy. A maleimide group is more preferable because a polymerization initiator is not required.

In General Formula (1), X ¹ represents a linking group represented by — (A ¹ -B ¹ ) _m —, and X ² represents a linking group represented by — (B ² -A ² ) _n —. To express. Here, A ¹ and A ² each independently represent a single bond or a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include alkylene groups having 1 to 20 carbon atoms such as ethylene group, methylene group, propylene group, pentamethylene group and heptylene group; 3 to 3 carbon atoms such as cyclopropylene group and cyclohexylene group. 20 cycloalkylene group; arylene groups having 6 to 20 carbon atoms such as phenylene group and naphthylene group. Among these, an alkylene group is preferable and an alkylene group having 1 to 4 carbon atoms is more preferable.

B ¹ and B ² each independently represents a single bond, —O—, —CO—O—, —OCO—, —CONH—, —NHCO—, —NHCO—O—, or —OCONH—. m and n each independently represents an integer of 1 to 4. When m or n is 2 or more, a plurality of A ¹ , B ¹ , A ² and B ² may be the same or different. However, A ¹ or A ² sandwiched between two B ¹ or B ² is not a single bond. Specifically, when m is ^{2, - (A 1 -B 1} ) m - linking group represented _{by, -CH 2 CH 2 -O-CH} 2 CH 2 CH 2 CH 2 -CO-O- or _{represents -O-CH 2 CH 2 CH 2} -CO-O- and the like, when n is ^{2, - (B 2 -A 2} ) n - linking group represented by, -O-CO-Ph It represents the like - (phenylene _group) -O- _(CH 2) _6.

  Y represents a group having an azobenzene group, an anthraquinone group, a benzophenone group, a cinnamoyl group, a chalcone group or a coumarin group. Among these, a group having the following structure is preferable.

In the above structure, p _{1 to} p ₁₁ are each independently a hydrogen atom, a halogen atom, a halogenated alkyl group, a halogenated alkoxy group, a cyano group, a nitro group, an alkyl group, a hydroxyalkyl group, an alkoxy group, an aryl group, An allyloxy group, an alkoxycarbonyl group, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxy group is represented. However, the carboxyl group and the sulfonic acid group may form a salt with an alkali metal.

  Specific examples of the compound represented by the general formula (1) include the compounds described in JP-A No. 2002-250924 and JP-A No. 2002-317013. It can be easily synthesized.

  Since the compound represented by the general formula (1) has a low molecular weight, it is excellent in sensitivity to light when formed into a coating film. Therefore, liquid crystal alignment ability can be easily imparted by light irradiation. In addition, since the polymerizable group has a higher degree of freedom than the polymerizable group bonded to the polymer, the reaction rate is high, and the layer (A) 11 and the layer (B) 12 can be reacted well at the interface. Excellent adhesion.

  Compound (D) includes azo dye, anthraquinone dye, indigo dye, phthalocyanine dye, carbonium dye, quinoneimine dye, methine dye, quinoline dye, nitro dye, nitroso dye, benzoquinone dye, naphthoquinone dye, naphthalimide dye, perinone dye, etc. Specifically, the compound represented by the general formula (2) is preferable.

In the formula, X ¹ , Y, and X ² represent the same group as the group represented by the general formula (1).
R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a sulfonic acid group, a sulfonic acid group, a halogenated methyl group, a cyano group, an amino group, a formyl group, a carboxyl group, a piperidino group And general formula (3)

(Wherein R ⁵ represents a hydrogen atom, an alkyl group, a cycloalkyl group, a phenyl group, a piperidino group; and an alkyl group, a cycloalkyl group, a phenyl group, an alkoxyl group, a cycloalkoxyl group, or a phenoxy group bonded to these groups. Represents an organic group.)
Represents one or more groups selected from the group consisting of

(Compound (E))
As the compound (E), for example, polymerization having (meth) acryloyl group, (meth) acryloyloxy group, (meth) acrylamide group, vinyl group, vinyloxy group, azide group, chloromethyl group, epoxy group, maleimide group, etc. Compound. Of these, acrylic monomers having a strong tendency to hydrophilicity and hydroxyl groups and ethylene glycol units, silane coupling agents such as methacrylic acid-3-trimethoxysilylpropyl ether, and the like are preferable. The compound (E) can be used by adding to the compound (C) within a range not impairing the photo-alignment property. As a specific addition amount, 10-95 mass% is preferable, 20-90 mass% is still more preferable, 20-50 mass% is still more preferable.
Although there is no restriction | limiting in particular in the molecular weight of a compound (E), Usually, it is preferable to use a thing about 50-1000 converted into a mass mean molecular weight. When the molecular weight is too high, the compound (D) becomes difficult to move in the system, and the sensitivity to light tends to decrease. In general, the higher the polymer, the better the film formability and the smoother surface coating film is obtained. In the present invention, when the surface of the layer (A) 11 is very smooth, There may be borders and optical effects.
As for the “optical influence” here, the transmitted light intensity ratio is one of the indexes. For example, the contrast is expressed as a ratio of transmitted light intensity at the time of bright display to a low transmitted light intensity almost at 0.0 at the time of dark display. That is, if the transmitted light intensity ratio in the direction tilted with respect to the front is reduced even by 1.0%, the actually measured contrast is further reduced, and the contrast viewing angle characteristic is greatly reduced.

  The compounds (C), (D) and (E) are preferably used after being dissolved in an appropriate solvent. The solvent is not particularly limited, but glycols such as ethylene glycol, propylene glycol and dipropylene glycol monomethyl ether, alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, water, N-methylpyrrolidone (hereinafter, NMP), butyl cellosolve, phenyl cellosolve, N, N-dimethylformamide (hereinafter abbreviated as DMF), γ-butyrolactone, dimethyl sulfoxide (hereinafter abbreviated as DMSO), toluene, tetrahydrofuran, chlorobenzene, dimethylacetamide and the like. Is mentioned. These solutions are preferably selected in consideration of the coating property, the volatilization rate of the solvent after coating, and the solvent resistance of the substrate, and two or more types can be mixed and used. Among them, a mixed solvent composed of a mixed solvent of butyl cellosolve and water, and alcohols or glycols has good applicability to a substrate such as a polymer film, and a uniform film can be obtained without damaging the polymer film. Is particularly preferred.

  Since the solvent is volatilized and removed after being applied to the substrate, the solid content concentration of the compound (C) needs to be at least 0.2% by mass or more when used. Especially, the range of 0.3-10 mass% is especially preferable. In addition, a polymer material such as polyvinyl alcohol or polyimide can be mixed within a range not impairing the effects of the present invention.

The film thickness of the layer (A) 11 is preferably reduced because the ultraviolet energy used for the alignment treatment can be kept low and the production rate can be increased. However, if the film thickness is too thin, the influence of the surface smoothness or surface characteristics of the substrate is preferable. The orientation uniformity is poor. Therefore, there is an optimal range. The thickness of the layer (A) 11 is preferably 1 to 200 nm, more preferably 5 to 100 nm, and most preferably 10 to 40 nm.

(Layer (B) 12)
In the present invention, the liquid crystal compound having a polymerizable group contained in the polymerizable liquid crystal composition constituting the layer (B) 12 has a polymerizable group that exhibits liquid crystallinity alone or in a composition with another liquid crystal compound. If it is a compound which has, there will be no limitation in particular. For example, Handbook of Liquid Crystals Handbook of Liquid Crystals (D Deems D. Demus, J Double Goodby J. W. Goodby, G Double Gray GW Gray, H. V. Sp. Edited by Wiley-VH, published by Wiley-VCH, 1998), Quarterly Chemical Review No. 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. Examples thereof include a rod-like liquid crystal compound having a rigid site called a mesogen in which a plurality of structures such as a silene group are connected, and a polymerizable group such as a (meth) acryloyl group, a vinyloxy group, and an epoxy group.

Also, for example, Handbook of Liquid Crystals Handbook of Liquid Crystals (D. Demus D. Demus, J. Double Goodby J. W. Goodby, G. Double Gray, G. W. Gray, H.S. Edited by Vill, published by Wiley-VCH, 1998), quarterly chemistry review article No. 22. Discotic liquid crystal compounds having a polymerizable group described in the chemistry of liquid crystals (edited by the Chemical Society of Japan, 1994) and JP-A-07-146409. Among these, a rod-like liquid crystal compound having a polymerizable group is preferable because a liquid crystal phase temperature range that includes a low temperature around room temperature is easy to make.

(Process (I))
An example is given as a specific embodiment of the step (I).

1. A method of adding a photopolymerization initiator to the polymerizable liquid crystal composition layer A photoalignable polymerizable composition containing no polymerization initiator is applied onto a substrate and dried, and then the compound (C) or Irradiation with polarized light having a wavelength that can be absorbed by the photo-alignable group of (D) gives liquid crystal alignment ability. When the photo-alignable group is a group utilizing molecular orientation induction or isomerization reaction by the Weigert effect, the liquid crystal is irradiated with non-polarized light having a wavelength that the group efficiently absorbs from the oblique direction. An orientation function may be provided (this is the same for other embodiments). Next, when a polymerizable liquid crystal composition solution containing a photopolymerization initiator is applied thereon and dried, the polymerizable liquid crystal composition layer has an intended alignment state due to the effect of the liquid crystal alignment ability of the photoalignable polymerizable composition layer. Take. Next, two layers of light having a wavelength that is absorbed by the added photopolymerization initiator are irradiated to advance the curing of the polymerizable liquid crystal compound, and at the same time, the polymerizable liquid crystal composition layer and the photoalignable polymerizable composition layer Polymerization is carried out between the molecules of both layers by a photopolymerization initiator present at the interface. Since radicals generated by the cleavage of the photopolymerization initiator can move between both layers, if a photopolymerization initiator is contained in either layer, the polymerizable groups present at the interface between the two layers are polymerized. The layer (A) 11 and the layer (B) 12 can be covalently bonded to obtain an optically anisotropic layer 13 with improved adhesion. Further, in this method, since the photoalignable polymerizable composition does not contain a photopolymerization initiator, there is no possibility that unexpected polymerization occurs during irradiation of polarized light or the like, and the alignment treatment can be performed uniformly.

Alternatively, a polymerizable liquid crystal composition layer containing a photopolymerization initiator is formed on the transparent substrate without applying orientation, after applying a photoalignable polymerizable composition containing no polymerization initiator on the transparent substrate and drying. Next, from the transparent substrate side (surface opposite to the coating film surface), the polarized light having a wavelength that can be absorbed by the photoalignable group of the compound (C) or (D) or non-oblique from the oblique direction to the substrate. Irradiate polarized light. In this method, the photo-alignment group in the photo-alignment polymerizable composition absorbs most of the irradiation light, and the liquid crystal alignment ability is generated. Orient. As the irradiation progresses, the irradiation light is transmitted through the photoalignable polymerizable composition layer by the mechanism described below, reaches the polymerizable liquid crystal composition layer, and cleaves the photopolymerization initiator in the layer. In addition to inducing a polymerization reaction, bonding between the photo-alignable polymerizable composition layer and the polymerizable liquid crystal composition layer also occurs.
That is, when light irradiation is performed from the transparent substrate side, an isomerization reaction such as an azobenzene group occurs and molecular alignment due to the Weigert effect is induced. The direction changes and takes an orientation state that minimizes absorption. Therefore, the irradiation light gradually leaks into the polymerizable liquid crystal composition layer, and induces polymerization of the polymerizable liquid crystal composition layer. Similarly, in the photo-alignment polymerizable composition layer, a compound utilizing a dimerization reaction (eg, cinnamoyl group), a photocrosslinking reaction (eg: benzophenone group), or a photolysis reaction (eg: polyimide group) was used. In some cases, the components oriented in the direction due to the absorption of polarized light are dimerized, photocrosslinked, photodecomposed, and the group that absorbs light gradually decreases, so that the irradiation light leaks to the polymerizable liquid crystal composition layer. Thus, polymerization of the polymerizable liquid crystal composition layer is induced. Therefore, the layer (A) 11 and the layer (B) 12 are covalently bonded, and the optically anisotropic layer 13 with improved adhesion can be obtained. Also in this case, since the photo-alignable polymerizable composition does not contain a photopolymerization initiator, there is no possibility of unexpected polymerization during irradiation of polarized light, and the alignment treatment can be performed uniformly.

2. A photopolymerization initiator having a light absorption wavelength band different from the light absorption band of compound (C) or (D) is added to one or both of the polymerizable liquid crystal composition and the photoalignable polymerizable composition. Method of applying After the photoalignable polymerizable composition solution is applied on the substrate and dried, the polarized light having a wavelength that can be absorbed by the photoalignable group of the compound (C) or (D) or obliquely with respect to the substrate Irradiation with non-polarized light gives liquid crystal alignment ability. A polymerizable liquid crystal composition solution is applied thereon, and after drying, the polymerizable liquid crystal compound is brought into an intended alignment state. Next, the laminated two layers are irradiated with light having a wavelength that is absorbed by the added photopolymerization initiator, and bonds between molecules at the interface between the polymerizable liquid crystal composition layer and the photoalignable polymerizable composition layer. Curing of each of the polymerizable liquid crystal compound and the compound (C) or the compound (E) is also advanced. Also by such an operation, the optically anisotropic layer 13 in which the layer (A) 11 and the layer (B) 12 are covalently bonded and the adhesion between both layers is improved can be obtained.

3. A method in which a thermal polymerization initiator is added to one or both of a polymerizable liquid crystal composition and a photoalignable polymerizable composition. After a photoalignable polymerizable composition solution is applied on a substrate and dried, the compound (C ) Or (D) is irradiated with polarized light having a wavelength that can be absorbed by the photo-alignable group or non-polarized light from an oblique direction to the substrate to give liquid crystal alignment ability. Next, a polymerizable liquid crystal composition layer is formed on the layer, and both layers are heated to cleave the thermal polymerization initiator to proceed with curing of both layers, and at the same time, the polymerizable liquid crystal composition layer and the photo-alignment polymerization The molecules of both layers are polymerized by a thermal polymerization initiator present at the interface with the conductive composition layer. The radicals generated by the cleavage of the thermal polymerization initiator can move in both layers, so if they are contained in either layer, the polymerizable groups present at the interface between both layers can be polymerized. The layer (A) 11 and the layer (B) 12 are covalently bonded to obtain an optically anisotropic layer 13 with improved adhesion.

4). Method of using thermal polymerization initiator and photopolymerization initiator in combination After coating and drying a photoalignable polymerizable composition containing a thermal polymerization initiator on a substrate, the photoalignable group of compound (C) or (D) Irradiates polarized light having a wavelength that can be absorbed or non-polarized light from an oblique direction with respect to the substrate to give liquid crystal alignment ability. Next, a polymerizable liquid crystal composition layer containing a photopolymerization initiator is formed on the layer, and the two layers thus laminated are absorbed by the photopolymerization initiator while being heated to an appropriate temperature at which the thermal polymerization initiator is cleaved. By irradiating light with a wavelength to be cured, both layers are cured and at the same time, the molecules of both layers are polymerized.

  Alternatively, a photopolymerization initiator having a light absorption wavelength band different from the absorption band of the photoalignable polymerizable composition itself is added to the photoalignable polymerizable composition, and after film formation and drying, the compound (C) or ( The polarized light that can be absorbed by the photo-alignable group of D) or non-polarized light from an oblique direction is applied to the substrate to give liquid crystal alignment ability. Next, a polymerizable liquid crystal composition layer to which a thermal polymerization initiator is added is formed on the layer, and simultaneously curing both phases by irradiating light absorbed by the photopolymerization initiator while heating both layers. Polymerize between the molecules of both layers. By such an operation, a retardation film with improved adhesion can be obtained by providing bonding between the photo-alignable polymerizable composition layer and the polymerizable liquid crystal composition layer.

(Application method)
The method of forming each composition layer on the substrate includes spin coating method, extrusion method, gravure coating method, die coating method, bar coating method, application method such as applicator method and printing method such as flexo method, etc. Any known method can be used.

(substrate)
The substrate is not particularly limited as long as it is substantially transparent, and glass, ceramics, plastics, and the like can be used. Examples of plastic substrates include cellulose derivatives such as cellulose, triacetyl cellulose, diacetyl cellulose, polycycloolefin derivatives, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polypropylene, and polyethylene. Polyolefin, polycarbonate, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, nylon, polystyrene, polyacrylate, polymethyl methacrylate, polyether sulfone, polyarylate and the like can be used.
The optical film 10 of the present invention produced by coating on a substrate may be bonded to a linearly polarizing film, the optical film 10 formed by coating may be peeled off from the substrate and bonded to the linearly polarizing film, The optical film 10 of the present invention can be directly formed on a polarizing film or a polarizing plate to obtain a circularly polarizing plate and an elliptically polarizing plate. An example of a circularly polarizing plate or an elliptically polarizing plate is shown in FIG. In FIG. 2, the code | symbol 20 shows a polarizing plate.

(Optical alignment operation)
In order to impart liquid crystal alignment ability to the photoalignable polymerizable composition layer (hereinafter abbreviated as photoalignment operation), polarized light having a wavelength that can be absorbed by the photoalignable group of the compound (C) or (D). Irradiation from the coating film surface or the substrate side opposite to the coating film surface may be performed perpendicularly to the surface or from an oblique direction. In addition, when the photo-alignable group is a group utilizing molecular orientation induction or isomerization reaction due to the Weigert effect, non-polarized light having a wavelength that the group efficiently absorbs from the coating film surface or the substrate side. The liquid crystal alignment function may be given by irradiating the surface from an oblique direction. Also, polarized light and non-polarized light may be combined.
The polarized light may be either linearly polarized light or elliptically polarized light, but it is preferable to use linearly polarized light having a high extinction ratio in order to perform photoalignment efficiently.

  Moreover, since it is necessary to use a polarizing filter in order to obtain polarized light, there is a disadvantage that the light intensity irradiated on the film surface is reduced, but in the method of irradiating non-polarized light from an oblique direction with respect to the film surface The irradiation apparatus does not require a polarizing filter, and there is an advantage that a large irradiation intensity can be obtained and the irradiation time for photo-alignment can be shortened. At this time, the incident angle of non-polarized light is preferably in the range of 10 ° to 80 ° with respect to the normal to the substrate. In consideration of the uniformity of the irradiation energy on the irradiated surface, the pretilt angle obtained, the alignment efficiency, etc. A range of 60 ° is most preferred.

The light to be irradiated may be light in a wavelength region in which the photoalignable group of the compound (C) or (D) has an absorption band. For example, when the photo-alignment group has an azobenzene structure, ultraviolet rays having a wavelength of 350 to 500 nm with a strong absorption band due to the π → π ^* transition of azobenzene are particularly preferable. Examples of the light source for irradiation light include xenon lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, metal halide lamps, ultraviolet lasers such as KrF and ArF, and the like. In particular, when the photo-alignment group has an azobenzene structure, the ultra-high pressure mercury lamp is particularly preferable because the emission intensity of ultraviolet light at 365 nm is large. Ultraviolet linearly polarized light can be obtained by passing the light from the light source through a polarizing prism such as a polarizing filter, Glan-Thompson, and Glan-Teller. Moreover, it is particularly preferable that the irradiated light is substantially parallel light regardless of whether polarized light or non-polarized light is used. The light to be irradiated may be irradiated from the surface side of the coating film or from the substrate side. In the case of irradiation from the substrate side, a transparent substrate is used as the substrate.

(polymerization)
The polymerization operation of the photo-alignable polymerizable composition and the polymerizable liquid crystal composition of the present invention is generally performed by irradiation with light such as ultraviolet rays or heating.
In the case where the polymerization is performed by light irradiation, in order not to disturb the alignment state of the photoalignable polymerizable composition layer that has already been obtained, in general, the light absorption band of the compound (C) or (D) For example, it is preferably performed at a wavelength other than the absorption band of the azobenzene skeleton or anthraquinone skeleton. Specifically, it is preferable to irradiate ultraviolet light of 320 nm or less, and most preferable to irradiate light having a wavelength of 250 to 300 nm. This light is preferably diffused light and unpolarized light so as not to disturb the orientation of the photoalignable group already obtained. Therefore, usually, it is preferable to use a photopolymerization initiator having a light absorption wavelength band different from the light absorption band of the compound (C) or (D). On the other hand, when the light for polymerization is irradiated from the same direction as the photo-alignment operation, any wavelength can be used because there is no fear of disturbing the alignment state of the photo-alignment material.

  As the photopolymerization initiator, known ones can be used. For example, 2-hydroxy-2-methyl-1-phenylpropan-1-one ("Darocur 1173" manufactured by Merck & Co., Inc.), 1-hydroxycyclohexyl phenyl ketone (Ciba Specialty Chemicals “Irgacure 184”), 1- (4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (Merck “Darocur 1116”), 2-methyl-1-[( Methylthio) phenyl] -2-morpholinopropane-1 (“Irgacure 907” manufactured by Ciba Specialty Chemicals), benzylmethylketal (“Irgacure 651” manufactured by Ciba Specialty Chemicals), 2,4- Diethylthioxanthone (“Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.) and p-di A mixture of ethyl tilaminobenzoate (“Kayacure EPA” manufactured by Nippon Kayaku Co., Ltd.), a mixture of isopropylthioxanthone (“Cancure-ITX” manufactured by Word Prekinsop Co., Ltd.) and ethyl p-dimethylaminobenzoate, acylphosphine oxide ( BASF “Lucirin TPO”) and the like. 10 mass% or less is preferable with respect to a composition, and, as for the usage-amount of a photoinitiator, 0.5-5 mass% is especially preferable.

  Light for polymerization may be irradiated from the surface of the polymerizable liquid crystal composition layer or from the substrate side, and may be arbitrary, but is usually irradiated from the side to which the photopolymerization initiator is added.

  On the other hand, the polymerization by heating is preferably performed at a temperature at which the polymerizable liquid crystal composition exhibits a liquid crystal phase or at a lower temperature. In particular, when a thermal polymerization initiator that releases radicals by heating is used, the cleavage temperature is preferably in the liquid crystal phase temperature range of the polymerizable liquid crystal composition or lower. Further, when the thermal polymerization initiator and the photopolymerization initiator are used in combination, the polymerization rate of the photoalignable polymerizable composition layer and the polymerizable liquid crystal composition layer is greatly different from the above temperature range limitation. It is preferable to select the polymerization temperature and the respective initiators so that there is no occurrence. Although the heating temperature depends on the transition temperature from the liquid crystal phase to the isotropic phase of the polymerizable liquid crystal composition, it is preferably performed at a temperature lower than the temperature at which inhomogeneous polymerization is induced by heat. 300 degreeC is preferable, 30 to 200 degreeC is more preferable, and 30 to 120 degreeC is especially preferable. For example, when a polymeric group is a (meth) acryloyl group, it is preferable to carry out at the temperature lower than 90 degreeC, and 30 to 90 degreeC is more preferable.

  In the above case, it is preferable to use a thermal polymerization initiator as appropriate. As the thermal polymerization initiator, known and commonly used ones can be used. For example, methyl acetoacetate peroxide, cumene hydroperoxide, benzoyl peroxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, t- Butyl peroxybenzoate, methyl ethyl ketone peroxide, 1,1-bis (t-hexyl peroxy) 3,3,5-trimethylcyclohexane, p-penta hydroperoxide, t-butyl hydroperoxide, dicumyl per Organic peroxides such as oxide, isobutyl peroxide, di (3-methyl-3-methoxybutyl) peroxydicarbonate, 1,1-bis (t-butylperoxy) cyclohexane; 2,2′-azobisiso Butyronitrile, 2,2'-azobis (2, Azonitrile compounds such as 2-dimethylvaleronitrile); azoamidin compounds such as 2,2′-azobis (2-methyl-N-phenylpropion-amidin) dihydrochloride; 2,2′azobis {2-methyl-N- [1 , 1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide} and the like; alkylazo compounds such as 2,2′azobis (2,4,4-trimethylpentane) and the like can be used. 10 mass% or less is preferable with respect to a composition, and, as for the usage-amount of a thermal-polymerization initiator, 0.5-5 mass% is especially preferable.

  The polymerization initiators such as the photopolymerization initiator and the thermal polymerization initiator shown above are included in either the photo-alignment polymerizable composition layer or the polymerizable liquid crystal composition layer having a polymerizable group. It may be included in both. Since the interface between both layers is liquid, the polymerization initiator and radicals generated by the cleavage of the polymerization initiator can move to both layers to some extent. Therefore, if it is contained in either layer, both layers can be polymerized at the same time, and the optically anisotropic layer 13 in which the layers (A) 11 and (B) 12 are covalently bonded and laminated is obtained. be able to.

  For example, the photo-alignment polymerizable composition does not contain a polymerization initiator, and when the polymerizable liquid crystal composition contains a polymerization initiator, the polymerization initiator becomes a photo-alignment polymerizable composition layer from the polymerizable liquid crystal composition layer. Move slightly. Further, by applying light or heat, radicals generated in the polymerizable liquid crystal composition are transferred to the photo-alignable polymerizable composition layer, and both layers and their interfaces can be polymerized.

The thinner the optical film 10 obtained, the better, but considering the ease of film thickness control and the birefringence of the polymerizable liquid crystal cured film, the optical anisotropy comprising the photo-alignment film and the polymerizable liquid crystal layer is preferable. The preferable film thickness of one layer of the layer 13 is preferably 0.1 to 20 μm, more preferably 0.5 to 10 μm, and most preferably 1 to 5 μm.

In the present invention, the optical anisotropic layer 13 obtained by repeating step (I) a plurality of times, the number of laminated layers, the azimuth angle with respect to the incident light, and the retardation value are the desired circularly polarizing plate or elliptically polarized light. It can be arbitrarily selected and combined according to the required characteristics of the plate.

(Number of layers)
As the number of stacked layers increases, a broadband polarizing plate can be obtained, so that there is no particular limit value. However, if too many layers are stacked, the film thickness becomes thick and it is not practical. Therefore, it is preferable that the optically anisotropic layer 13 is not less than 2 and not more than 20 layers. Usually, a laminate of 2 to 5 layers is preferable, and a laminate of 2 to 3 layers is practical.

(Azimuth)
The azimuth angle can be arbitrarily selected from the range of 0 to 180 ° (0 to −180 °).

(Phase difference)
The phase difference is determined according to the purpose of use of the optical film 10 and the wavelength region used. For example, when used in the visible light region, the phase difference at a wavelength of 540 nm is 240 to 320 μm for a half-wave plate and 120 to 160 μm for a quarter-wave plate. Larger film thicknesses can be used, but the film thickness is increased. For example, a combination of the optically anisotropic layer 13 having a retardation measured at a wavelength of 540 nm of 240 to 300 nm and the optically anisotropic layer 13 of 120 to 150 nm is preferable.
The phase difference can be measured by, for example, an automatic birefringence meter.

(Regulation accuracy of optical axis of plural optically anisotropic layers 13)
By laminating the optically anisotropic layer 13 at a specific angle, various optical functions can be exhibited. This lamination angle can be obtained by calculation based on a theoretical formula. Many laminated structures have already been proposed.
A method of combining the tilt angle and the phase difference of the wave plate with respect to the incident light will be described using a Poincare sphere that is often used as a polarization display method. By placing an appropriate retardation plate (first retardation plate) corresponding to a half-wave plate with respect to the incident polarization, the oscillation direction of the incident polarization is changed, and the polarization state is moved onto an arbitrary equator on the Poincare sphere. (First polarization state). However, the incident light contains component light having a wavelength deviated from the ½ wavelength condition, and these light beams are broadened by the first phase difference plate, so that the polarization state after transmission through the first phase difference plate is Poincare. It must be aligned on the meridian passing through the first polarization state on the sphere or at a position as close as possible.
For this purpose, the first retardation plate may be composed of one half-wave plate or may be composed of a plurality of half-wave plates. A plurality of retardation plates having the above may be used, or a combination of these and a half-wave plate may be used.
Circularly polarized light is obtained by passing the light transmitted through the first retardation plate through the quarter-wave plate and moving the polarization state to the pole on the Poincare sphere. The circularly polarized light in which all the wavelengths of light are in the same polarization state by canceling out the difference in phase difference caused by the wavelength of the incident light generated when it passes through the first retardation plate by passing through this quarter-wave plate. It becomes. Conversely, the configuration of the first retardation plate needs to be combined so as to eliminate the phase difference for each wavelength after passing through the quarter-wave plate.
Theoretically, a large difference in optical function occurs only when the obtained setting angle is deviated by 1 °. Therefore, it is necessary to stack two optical anisotropic layers 13 precisely as designed values. The optical film 10 of the present invention easily obtains a laminate of the optically anisotropic layer 13 oriented in an arbitrary orientation direction by arbitrarily changing the irradiation direction of ultraviolet rays or the vibration direction of polarized light in (Step b). It is possible. Specifically, it is possible to obtain the optical film 10 in which the angles formed by the slow axes of the optically anisotropic layer 13 are laminated with a lamination angle error within a desired angle ± 0.1 °. .

  In the case of a liquid crystal display element, in order to make the angle formed by the alignment direction of the liquid crystal compound adjacent to the substrate and the optical axis (slow axis) of the optically anisotropic layer 13 as close as possible to the design value, specifically, The following manufacturing method is performed.

  As a specific embodiment of the present invention, an example in which a long film is used as a substrate will be described here.

1) A broadband quarter-wave plate in which an optical anisotropic layer 13 functioning as a half-wave plate and an optical anisotropic layer 13 functioning as a quarter-wave plate are laminated, and the broadband quarter wavelength Manufacturing method of broadband circularly polarizing plate in which plate and polarizing plate 20 are laminated (Step a) A photo-alignable polymerizable composition is applied on a long film and dried.
(Step b) Ultraviolet rays are irradiated on the layer obliquely from a direction inclined by an azimuth angle of 75 ° (or −105 °) with respect to the longitudinal direction of the film, for example, a polar angle of 45 ° from the normal direction of the film. By irradiating at an angle, the layer (A) 11 having liquid crystal alignment ability is formed in a direction inclined by an azimuth angle of 75 ° from the longitudinal direction of the film. Alternatively, by using a polarized ultraviolet ray irradiation device positioned in the normal direction of the film, the irradiation may be performed such that the vibration direction of polarized light is inclined 165 ° (or −15 °) as the azimuth from the longitudinal direction of the film. The layer (A) 11 having liquid crystal alignment ability can be formed in a direction inclined by an azimuth angle of 75 ° from the longitudinal direction of the film. At this time, the irradiation direction of the ultraviolet rays can be arbitrarily selected according to the arrangement and structure of the irradiation device irrespective of the conveying direction of the long film. It is also easy to set the accuracy of the rotation mechanism of the optical system to an azimuth angle of 1.0 to 0.01 °.
(Step c) On the obtained layer (A) 11, a liquid crystal compound whose thickness is controlled so that the phase difference becomes ½ wavelength at the wavelength of incident light is applied and aligned on the layer (A) 11. Let
(Step d) By polymerizing these two layers simultaneously by ultraviolet irradiation, the layer (A) 11 and the layer (B) 12 were covalently bonded, and the slow axis was inclined by 75 ° in the azimuth from the film longitudinal direction. An optically anisotropic layer 13 that functions as a half-wave plate can be formed.

Next, the above-mentioned (Step a) to (Step d) are repeated on the obtained optically anisotropic layer 13. At this time, the irradiation direction of ultraviolet rays in (step b) is oblique irradiation from a direction inclined by an azimuth angle of 15 ° (or −165 °) with respect to the longitudinal direction of the film, for example, 45 ° polar angle from the normal direction of the film. Tilt to irradiate. By doing in this way, the layer (A) 11 which has liquid crystal aligning ability can be formed in the direction inclined 15 degrees from the longitudinal direction of the film. Alternatively, even if a polarized ultraviolet ray irradiation device located in the normal direction of the film is used to irradiate the polarized light with an azimuth angle of 105 ° (or −75 °) from the longitudinal direction of the film, The layer (A) 11 having liquid crystal alignment ability can be formed in a direction inclined by an azimuth angle of 15 °. The film thickness of the polymerizable liquid crystal composition layer in (Step c) is such that the phase difference is the optically anisotropic layer 13 that functions as a quarter wavelength at the wavelength of the incident light. Thereby, a broadband quarter wavelength plate can be easily produced.
By laminating the wide-band quarter-wave plate and the long polarizing plate 20 having the absorption axis in the longitudinal direction, the wide-band circularly polarizing plate can be easily formed.

2) A broadband quarter-wave plate in which two layers of the optical anisotropic layer 13 functioning as a half-wave plate and an optical anisotropic layer 13 functioning as a quarter-wave plate are laminated, and the broadband Method for producing broadband circularly polarizing plate in which quarter-wave plate and polarizing plate 20 are laminated The irradiation direction of ultraviolet rays in the first (step b) is azimuth 176 ° (or −) with the slow axis from the longitudinal direction of the film. 4 °), and the film thickness of the polymerizable liquid crystal composition layer in (step c) is set so that the phase difference is ½ wavelength at the wavelength of the incident light. The irradiation direction of ultraviolet rays in the second (step b) is such that the slow axis is an azimuth angle of 154 ° (or −26 °) from the longitudinal direction of the film, and the film thickness of the polymerizable liquid crystal composition layer in (step c) Is set so that the phase difference is ½ wavelength at the wavelength of the previous incident light. The irradiation direction of ultraviolet rays in the third (step b) is such that the slow axis is an azimuth angle of 91 ° (or −89 °) from the longitudinal direction of the film, and the film thickness of the polymerizable liquid crystal composition layer in (step c) The phase difference is set to ¼ wavelength at the wavelength of the previous incident light. By thus laminating the optically anisotropic layer 13, a broadband quarter-wave plate can be easily prepared, and the wide-band quarter-wave plate and a long polarizing plate whose absorption axis is in the longitudinal direction. 20 can be easily formed into a broadband circularly polarizing plate by laminating 20 with the longitudinal direction aligned.

(Optical isotropic resin layer)
The lamination of the optically anisotropic layer 13 in the present invention is performed by repeating the step (I) a plurality of times as described above. On the other hand, an optically isotropic resin layer may be provided between the two adjacent optically anisotropic layers 13 depending on the surface state of the substrate and the surface state of the layer laminated on the substrate. An example of the optical film 10 including the optically isotropic resin layer is shown in FIG. In FIG. 3, the code | symbol 14 shows an optically isotropic resin layer.
The material of the optically isotropic resin layer 14 is not particularly limited, but thermoplastic resins such as acrylic resins and polyvinyl alcohol, photopolymerizable resins such as acrylic monomers, and thermopolymerizable resins such as epoxy monomers. The used polymerizable resin or the like can be used. Among these, considering the smoothing of the surface of the optically isotropic resin layer 14 after coating, a polymer compound or a high-viscosity monomer capable of forming a high-viscosity coating liquid is desirable, and the viscosity is 200 to 20000 Pa · sec. Is desirable, and it is more desirable that it is 500 to 20000 Pa · sec.
The thickness of the optically isotropic resin layer 14 is not limited as long as it achieves the above-mentioned purpose. However, considering industrial application, it is desired to reduce the thickness and weight. It is desirable that the thickness is ˜30 μm, and more desirably 0.01 to 10 μm.
The optically isotropic resin layer 14 can be directly provided on the optically anisotropic layer 13 by a coating method. If necessary, polymerization by light irradiation or heat may be performed.

  By providing an optically isotropic resin layer 14 between the optically anisotropic layers 13 in which the adjacent layers (A) 11 and (B) 12 are bonded by a covalent bond, the adhesion or adhesion between the layers is improved. Or the flatness of the surface of the previous layer can be improved. Moreover, the optical film 10 can be created so that the different orientation directions of the adjacent optically anisotropic layers 13 do not affect. That is, since the surface orientation and surface state of the first layer (B) 12 can be avoided from affecting the second layer (A) 11, the ellipticity of the circularly polarizing plate is increased, and the elliptically polarizing plate The wavelength dependence of can be reduced. Further, interface reflection due to a difference in refractive index between layers having anisotropy can be avoided.

  A liquid crystal display element can be produced using the optical film 10 of the present invention. An example of this liquid crystal display element is shown in FIG. In FIG. 4, reference numerals 30, 40, and 50 denote a liquid crystal layer, an alignment film, and a pixel electrode, respectively.

(Polarizing plate 20)
The obtained optical film 10 can form an elliptically polarizing plate or a circularly polarizing plate by pasting with an appropriate polarizing plate 20 such as a linear polarizing plate. There is no restriction | limiting in particular as the polarizing plate 20, It can also combine with polarizing prisms, such as an iodine type and a dye-type polarizing film, and Glan Thompson, a grantor.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples. In the following examples, “%” and “part” represent “% by mass” and “part by mass”, respectively.

(Preparation of photoalignable polymerizable composition A-1)
The compound represented by the formula (1) was dissolved in a mixed solvent composed of 2-butoxyethanol, 1-butanol, water, and ethanol to obtain a 1% by mass solid content solution. This solution was filtered with a filter having a pore diameter of 0.1 μm to obtain a photoalignable polymerizable composition solution (A-1).

(Preparation of photoalignable polymerizable composition A-2)
40 parts by mass of the compound represented by the formula (2) and 60 parts by mass of the compound represented by the formula (3) are mixed and dissolved in a mixed solvent composed of 2-butoxyethanol, 1-butanol, water and ethanol. A 2% by weight solution was obtained. This solution was filtered through a filter having a pore size of 0.1 μm to obtain a photoalignable polymerizable composition solution (A-2).

(Preparation of photoalignable polymerizable composition A-3)
The compound represented by the formula (2) was dissolved in a mixed solvent composed of 2-butoxyethanol, 1-butanol, water and ethanol to obtain a 2% by mass solution. This solution was filtered through a filter having a pore size of 0.1 μm to obtain a photoalignable polymerizable composition solution (A-3).

(Preparation of photoalignable polymerizable composition A-4)
Polyvinyl cinnamate (manufactured by Aldrich, molecular weight 200,000) was dissolved in a solvent composed of NMP and 2-butoxyethanol to obtain a 1% by mass solid content solution. This was designated as photoalignable polymerizable composition (A-4).

(Preparation of polymerizable liquid crystal composition)
A compound represented by the formulas (4), (5), (6), (7), (8) is mixed so that the mass ratio is 22: 18: 33: 22: 5, respectively, and polymerizable liquid crystal A composition was prepared, and 0.5 parts by mass of the additive (9) having a mass average molecular weight of 47000 was mixed with 100 parts by mass of the polymerizable liquid crystal composition. Subsequently, it filtered with the filter of the hole diameter of 0.1 micrometer. 96 parts of this polymerizable liquid crystal composition was mixed with 4 parts of a photopolymerization initiator “Irgacure 907” manufactured by Ciba Specialty Chemicals Co., Ltd. and 100 parts of xylene to obtain a polymerizable liquid crystal composition solution (B-1). The liquid crystal composition after xylene was evaporated from the polymerizable liquid crystal composition solution (B-1) exhibited a liquid crystal phase at 25 ° C. Therefore, in the following examples, the liquid crystal composition was used at 25 ° C.

The optical film 10 obtained in the examples shown below was measured by the following evaluation method, and the results are shown in Table 1.
The phase difference was measured at a wavelength of 540 nm using an automatic birefringence meter (Cobra 21ADH (manufactured by Oji Scientific Instruments)). The wavelength dispersion of the ellipticity of the circularly polarizing plate was measured at each wavelength of 477.8 nm, 545.7 nm, and 628.6 nm using an automatic birefringence meter (Cobra 21ADH (manufactured by Oji Scientific Instruments)). Further, the adhesive force between the optical film 10 formed on the triacetyl cellulose (TAC) film and the TAC film was cut into a 1 mm square grid pattern with a cutter on the prepared retardation film, and serotape (cello tape) Is a registered trademark) and pulled up in the vertical direction, and the ratio of the number of grids remaining on the optical film 10 was determined. Defects generated in the film were evaluated by counting the number of points that were lost through observation under a polarizing microscope under crossed Nicols, and are shown in Table 1. The accuracy and reproducibility of the lamination angle of the optical film 10 was estimated from the values of the ellipticity measurement of a plurality of samples. The effective utilization rate of the optical film 10 was determined by the area of the optical film 10 that had to be discarded by clipping.

Example 1
After corona-treating the TAC film, the photo-alignable polymerizable composition solution (A-1) was spin-coated to form a 20 nm thick layer. This was dried at 80 ° C. and then subjected to orientation treatment, and ultraviolet rays through a 365 nm band pass filter were irradiated for 500 sec at an intensity of ² mW / cm ² from a direction inclined by 45 ° with respect to the layer surface, and the layer (A) 11 Formed. The azimuth angle indicated by the projection of the irradiated light onto the layer is 0 °. The layer (A) 11 is spin-coated with the polymerizable liquid crystal composition solution (B-1), dried at 80 ° C., irradiated with ultraviolet rays at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and the retardation measured at a wavelength of 540 nm is obtained. An optically anisotropic layer 13 having a thickness of 270 nm was obtained. Next, after corona treatment of this surface, a 5 wt% aqueous solution of polyvinyl alcohol (PVA) was spin coated and dried at 80 ° C. to provide the optically isotropic resin layer 14.
On top of this, the photo-alignable polymerizable composition solution (A-1) and the polymerizable liquid crystal composition solution (B-1) were applied under the same conditions as described above except that the azimuth angle was 60 ° and the phase difference was 135 nm. This was adhered on the polarizing plate 20 so that the TAC surface became a bonding surface, and a circularly polarizing plate was obtained. Regarding the stacking angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the wave plate having a phase difference of 270 nm was 75 °, and the angle between the slow axis of the wave plate having the phase difference of 135 nm was 15 °. .

(Example 2)
After polarizing plate 20 made of PVA and TAC impregnated with iodine was subjected to corona treatment, the photo-alignable polymerizable composition solution (A-1) was spin-coated to form a 20 nm thick layer. This was dried at 80 ° C. and then subjected to orientation treatment, and ultraviolet rays through a 365 nm band pass filter were irradiated for 500 sec at an intensity of ² mW / cm ² from a direction inclined by 45 ° with respect to the layer surface, and the layer (A) 11 Formed. The azimuth angle indicated by the projection of the irradiated light onto the layer (A) 11 is 0 °. The layer (A) 11 is spin-coated with the polymerizable liquid crystal composition solution (B-1), dried at 80 ° C., irradiated with ultraviolet rays at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and the retardation measured at a wavelength of 540 nm is obtained. An optically anisotropic layer 13 having a thickness of 270 nm was obtained. Next, after corona treatment of the surface, a 5 wt% aqueous solution of PVA was spin-coated and dried at 80 ° C. to provide an optically isotropic resin layer 14.
On this, the photo-alignment polymerizable composition solution (A-1) and the polymerizable liquid crystal composition solution (B-1) were applied under the same conditions as described above except that the azimuth angle was 60 ° and the phase difference was 135 nm. Regarding the stacking angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the wave plate having a phase difference of 270 nm was 75 °, and the angle between the slow axis of the wave plate having the phase difference of 135 nm was 15 °. .

(Example 3)
After corona treatment of the TAC film, the photo-alignable polymerizable composition solution (A-2) was spin-coated to form a 20 nm thick layer. This was dried at 80 ° C. and then subjected to orientation treatment, and ultraviolet rays through a 365 nm band pass filter were irradiated for 500 sec at an intensity of ² mW / cm ² from a direction inclined by 45 ° with respect to the layer surface, and the layer (A) 11 Formed. The azimuth angle indicated by the projection of the irradiated light onto the layer (A) 11 is 0 °. The layer (A) 11 is spin-coated with the polymerizable liquid crystal composition solution (B-1), dried at 80 ° C., irradiated with ultraviolet rays at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and the retardation measured at a wavelength of 540 nm is obtained. An optically anisotropic layer 13 having a thickness of 270 nm was obtained. Next, after corona treatment of the surface, a 5 wt% aqueous solution of PVA was spin-coated and dried at 80 ° C. to provide an optically isotropic resin layer 14.
On this, the photo-alignment polymerizable composition solution (A-2) and the polymerizable liquid crystal composition solution (B-1) were applied under the same conditions as described above except that the azimuth angle was 60 ° and the phase difference was 135 nm. This was adhered on the polarizing plate 20 so that the TAC surface became a bonding surface, and a circularly polarizing plate was obtained. Regarding the stacking angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the wave plate having a phase difference of 270 nm was 75 °, and the angle between the slow axis of the wave plate having the phase difference of 135 nm was 15 °. .

Example 4
After corona-treating the TAC film, the photo-alignable polymerizable composition solution (A-1) was spin-coated to form a 20 nm thick layer. This was dried at 80 ° C. and then subjected to an alignment treatment, and ultraviolet rays through a 365 nm band pass filter were irradiated for 500 sec at an intensity of ² mW / cm ² from a direction inclined by 45 ° with respect to the alignment layer surface, and the layer (A) 11 Formed. The azimuth angle indicated by the projection of the irradiated light onto the layer (A) 11 is 0 °. The layer (A) 11 is spin-coated with the polymerizable liquid crystal composition solution (B-1), dried at 80 ° C., irradiated with ultraviolet rays at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and the retardation measured at a wavelength of 540 nm is obtained. An optically anisotropic layer 13 having a thickness of 270 nm was obtained. Next, after corona treatment of this surface, the photo-alignment polymerizable composition solution (A-1) and the polymerizable liquid crystal composition solution (B-1) under the same conditions as described above except that the azimuth angle was 60 ° and the phase difference was 135 nm. Was applied. This was adhered on the polarizing plate 20 so that the TAC surface became a bonding surface, and a circularly polarizing plate was obtained. Regarding the stacking angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the wave plate having a phase difference of 270 nm was 75 °, and the angle between the slow axis of the wave plate having the phase difference of 135 nm was 15 °. .

(Example 5)
After corona treatment of the TAC film, the photo-alignable polymerizable composition solution (A-1) was continuously formed using a microgravure coater to form a 20 nm thick layer. This was dried at 80 ° C., and then subjected to orientation treatment, and polarized ultraviolet rays through a 365 nm bandpass filter were irradiated from the normal direction of the layer surface at 4 J / cm ² to form layer (A) 11. At this time, the direction of vibration of irradiated polarized light is set to a direction inclined by 15 ° with respect to the longitudinal direction of the film. The polymerizable liquid crystal composition solution (B-1) is applied onto the layer (A) 11 using a micro gravure coater, dried at 80 ° C., and then irradiated with ultraviolet light at 640 mJ / cm ^{2 in} a nitrogen atmosphere at a wavelength of 540 nm. An optically anisotropic layer 13 having a measured retardation of 270 nm and an azimuth angle of 75 ° with respect to the longitudinal direction of the slow axis film was obtained. Next, after corona treatment of this surface, the photo-alignment polymerizable composition solution (A-1) and the polymerizable liquid crystal composition solution (B-1) under the same conditions as described above except that the azimuth angle was 15 ° and the phase difference was 135 nm. Was applied. This was adhered on the polarizing plate 20 so that the TAC surface became a bonding surface, and a circularly polarizing plate was obtained. Regarding the stacking angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the wave plate having a phase difference of 270 nm was 75 °, and the angle between the slow axis of the wave plate having the phase difference of 135 nm was 15 °. .

(Example 6)
After corona treatment of the TAC film, the photo-alignable polymerizable composition solution (A-1) was continuously formed using a microgravure coater to form a 20 nm thick layer. This was dried at 80 ° C., and then subjected to orientation treatment, and polarized ultraviolet rays through a 365 nm bandpass filter were irradiated from the normal direction of the layer surface at 4 J / cm ² to form layer (A) 11. At this time, the direction of vibration of irradiated polarized light is set to a direction inclined by 15 ° with respect to the longitudinal direction of the film. The polymerizable liquid crystal composition solution (B-1) is applied onto the layer (A) 11 using a micro gravure coater, dried at 80 ° C., and then irradiated with ultraviolet light at 640 mJ / cm ^{2 in} a nitrogen atmosphere at a wavelength of 540 nm. An optically anisotropic layer 13 having a measured retardation of 135 nm and an azimuth angle of 75 ° with respect to the longitudinal direction of the slow axis film was obtained. Next, after corona-treating this surface, the same process is repeated once more, an anisotropic layer having an azimuth angle of 75 ° and a retardation of 135 nm is laminated, and together with the previously laminated anisotropic layer, an azimuth angle of 75 ° and a retardation is obtained. A 270 nm anisotropic layer was obtained. Next, after corona treatment of this surface, the photo-alignment polymerizable composition solution (A-1) and the polymerizable liquid crystal composition solution (B-1) under the same conditions as described above except that the azimuth angle was 15 ° and the phase difference was 135 nm. Was applied. This was adhered on the polarizing plate 20 so that the TAC surface became a bonding surface, and a circularly polarizing plate was obtained. Regarding the stacking angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the wave plate having a phase difference of 270 nm was 75 °, and the angle between the slow axis of the wave plate having the phase difference of 135 nm was 15 °. .

(Comparative Example 1)
After corona treatment of the TAC film, a 2-butoxyethanol solution of phenol novolac type epoxy acrylate having an acrylic group in the side chain of Dainippon Ink Chemical Co., Ltd. (concentration 30 wt% or less, solution for rubbing alignment film (C)) Was applied with a spin coater and dried at 60 ° C. for 30 minutes. This is rubbed, spin-coated with the polymerizable liquid crystal composition solution (B-1) on the alignment layer, dried at 80 ° C., irradiated with ultraviolet light at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and measured at a wavelength of 540 nm. The optically anisotropic layer 13 having a retardation of 270 nm was obtained.
In the same manner as in the above method, the optically anisotropic layer 13 was obtained by controlling the film thickness of another TAC film so that the phase difference was 135 nm. In order to bond these two types of wave plates to the polarizing plate 20, a rectangular wave plate was cut out according to the shape of the polarizing plate 20, and then bonded through an adhesive. At that time, the cut out raw material had to be discarded. Further, as the target lamination angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the 270 nm wave plate was 75 °, and the angle between the slow axis of the 135 nm wave plate was 15 °. . Therefore, it was tried to perform bonding by aligning one side of the film, but it was difficult to cut the slow axis in accordance with the direction of one side of the film, and the angle adjustment between the films was adjusted to match one side of the film. It was difficult to perform precisely. The wavelength dispersion of the ellipticity of this circularly polarizing plate was measured with an automatic birefringence meter, and the highest ellipticity among the repeated trial productions is shown in Table 1, but the variation between samples was quite large. In addition, as estimated from the ellipticity of the obtained circularly polarizing plate, the reproducibility of the stacking angle is poor, and the actual angle seems to have deviated from these values.

(Comparative Example 2)
After corona treatment of the TAC film, the photo-alignable polymerizable composition solution (A-3) was spin-coated to form a 20 nm thick layer. This is dried at 80 ° C. and then subjected to an alignment treatment, and ultraviolet rays through a 365 nm band pass filter are irradiated for 500 sec at an intensity of ² mW / cm ² from a direction inclined by 45 ° with respect to the layer surface to create a photo-alignment layer. did. The azimuth angle indicated by the projection of the irradiated light onto the photo-alignment layer is 0 °. A polymerizable liquid crystal composition solution (B-1) is spin-coated on the photo-alignment layer, dried at 80 ° C., irradiated with ultraviolet light at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and a retardation measured at a wavelength of 540 nm is 270 nm. An optically anisotropic layer 13 was obtained. Next, after corona treatment of the surface, a 5 wt% aqueous solution of PVA was spin-coated and dried at 80 ° C. to provide an optically isotropic resin layer 14.
On this, the photo-alignment polymerizable composition solution (A-3) and the polymerizable liquid crystal composition solution (B-1) were applied under the same conditions as described above except that the azimuth angle was 60 ° and the phase difference was 135 nm. This was adhered on the polarizing plate 20 so that the TAC surface became a bonding surface, and a circularly polarizing plate was obtained. Regarding the stacking angle, the angle between the absorption axis of the polarizing plate 20 and the slow axis of the wave plate having a phase difference of 270 nm was 75 °, and the angle between the slow axis of the wave plate having the phase difference of 135 nm was 15 °. .
Table 1 summarizes the above results.

From the difference between the measured ellipticity values obtained for Examples 1 to 6 and the calculated ellipticity values obtained by calculation, it was found that the error in the stacking angle was within 0.1 °. On the other hand, in Comparative Example 1, a stacking angle error exceeding 0.1 ° was observed.
In Comparative Example 2, the photoalignment layer and the polymer layer were not bonded by a covalent bond, so that the peel strength was not sufficient.

(Evaluation of transmitted light intensity)
(Example 7)
On a glass substrate, a photo-alignable polymerizable composition solution (A-1) (this is the photo-alignable polymerizable composition used in Example 1) was spin-coated, and a layer with a thickness of 20 nm was formed. After forming and drying at 80 ° C., the photo-alignment operation is performed by irradiating ultraviolet rays through a 365 nm band-pass filter at an intensity of ² mW / cm ² for 500 sec from a direction inclined by 45 ° with respect to the layer surface. 11 was formed. The azimuth angle indicated by the projection of the irradiated light onto the layer is 0 °. The layer (A) 11 is spin-coated with the polymerizable liquid crystal composition solution (B-1), dried at 80 ° C., irradiated with ultraviolet rays at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and the retardation measured at a wavelength of 540 nm is obtained. An optically anisotropic layer 13 having a thickness of 270 nm was obtained. Next, after corona treatment of the surface, a 5 wt% aqueous solution of polyvinyl alcohol (PVA) was spin coated and dried at 80 ° C. to provide the optically isotropic resin layer 14.
On this, the photo-alignment polymerizable composition solution (A-1) and the polymerizable liquid crystal composition solution (B-1) were applied under the same conditions as described above except that the azimuth angle was 60 ° and the phase difference was 135 nm. The optical film 10 on which the anisotropic layer 13 was laminated was obtained.

(Example 8)
A glass substrate is spin-coated with the photo-alignable polymerizable composition solution (A-4), dried at 100 ° C. for 2 minutes, and then irradiated with polarized ultraviolet rays through a 313 nm bandpass filter at 5 J / cm ^2. Photo-alignment operation was performed to form a layer (A) 11. The azimuth angle indicated by the vibration direction of the irradiated polarized light is 0 °. The layer (A) 11 is spin-coated with the polymerizable liquid crystal composition solution (B-1), dried at 80 ° C., irradiated with ultraviolet rays at 640 mJ / cm ^{2 in} a nitrogen atmosphere, and the retardation measured at a wavelength of 540 nm is obtained. An optically anisotropic layer 13 having a thickness of 270 nm was obtained. Next, after corona treatment of this surface, a 5 wt% aqueous solution of PVA was spin-coated and dried at 80 ° C. to provide an optically isotropic resin layer 14. A photo-alignable polymerizable composition solution (A-4) and a polymerizable liquid crystal composition solution (B-1) were applied on this under the same conditions as above except that the azimuth angle was 60 ° and the phase difference was 135 nm. The optical film 10 on which the anisotropic layer 13 was laminated was obtained.

(Comparative Example 3)
On the glass substrate, the optical film 10 in which the optically anisotropic layer 13 was laminated using the rubbing alignment film solution (C) was obtained in the same manner as in Comparative Example 1.

(Comparative Example 4)
The optical film 10 in which the optically anisotropic layer 13 was laminated on the glass substrate using the photoalignable polymerizable composition solution (A-3) was obtained in the same manner as in Comparative Example 2.

(Measurement method of transmitted light intensity)
The transmitted light intensity is measured by measuring the light transmittance using an automatic birefringence meter (Cobra 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.)) and in a direction inclined by 50 ° with respect to the transmitted light intensity in the film normal direction. It was expressed as a ratio of transmitted light intensity.
The results are shown in Table 2.

Example 7 is an example in which the low molecular weight compound represented by the general formula (1) is used as the composition for a photo-alignment film, and the transmitted light intensity ratio is as high as 73.8%. . Example 8 is an example in which polyvinyl cinnamate having a molecular weight of 200,000 was used as a composition for a photo-alignment film, but the transmitted light intensity ratio was relatively high, but compared with that using a low-molecular-weight photo-alignment film. And not low enough.
Comparative Example 3 is an example in which a rubbing resin polymer is used as the alignment film composition, but the transmitted light intensity ratio is the lowest. Comparative Example 4 is an example using the low molecular weight compound represented by the general formula (2), and the transmitted light intensity ratio is excellent.

From the results of Table 1 and Table 2, it can be accurately laminated with the positional relationship (lamination angle) of the optical axis as designed, and there is no peeling of the interface between the photo-alignment film and the polymerizable liquid crystal layer, and the durability is excellent. The optical film 10 having excellent transmitted light intensity ratio can be obtained from the optical film 10 described in Examples.

  The optical film 10 of the present invention, and the circularly polarizing plate and the elliptically polarizing plate formed by laminating the optical film 10 and the polarizing plate 20 are not limited to a reflection type liquid crystal display device, but can be used as an antireflection film for suppressing reflection on the surface. Can be used. These can be applied to a touch panel, an electric luminescence (EL) display, a reflective projector, and the like.

It is sectional drawing of an example of the optical film of this invention. It is sectional drawing of an example of the elliptically polarizing plate and circularly-polarizing plate using the optical film of this invention. It is sectional drawing of one example of the optical film of this invention containing an optically isotropic resin layer. It is sectional drawing of one example of the liquid crystal display element using the optical film of this invention.

Explanation of symbols

10 optical film 11 photo-alignment layer (A)
12 Polymer layer (B)
DESCRIPTION OF SYMBOLS 13 Optical anisotropic layer 14 Optical isotropic resin layer 20 Polarizing plate 30 Liquid crystal layer 40 Orientation film 50 Pixel electrode

Claims (12)

A composition having a dichroic dye having a polymerizable group represented by the general formula (1), or a composition containing a dichroic dye represented by the general formula (2) and a polymerizable compound; A polymer layer obtained by polymerizing the photo-alignment layer (A) having a liquid crystal alignment ability by light irradiation and a liquid crystal compound having a polymerizable group and being aligned by the photo-alignment layer (A). An optical film, wherein a plurality of optically anisotropic layers bonded with (B) by a covalent bond are laminated.

(In General Formula (1), R ¹ and R ² each independently comprise a (meth) acryloyl group, a (meth) acryloyloxy group, a (meth) acrylamide group, a vinyl group, a vinyloxy group, and a maleimide group. Represents a polymerizable group selected from the group;
X ¹ represents a linking group represented by — (A ¹ -B ¹ ) _m —, and X ² represents a linking group represented by — (B ² -A ² ) _n —. Here, A ¹ and A ² are each independently a single bond, an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or an arylene group having 6 to 20 carbon atoms. To express.
B ¹ and B ² each independently represents a single bond, —O—, —CO—O—, —OCO—, —CONH—, —NHCO—, —NHCO—O—, or —OCONH—. m and n each independently represents an integer of 1 to 4. When m or n is 2 or more, a plurality of A ¹ , B ¹ , A ² and B ² may be the same or different. However, A ¹ or A ² sandwiched between two B ¹ or B ² is not a single bond.
Y represents a group having an azobenzene group, an anthraquinone group, a benzophenone group, a cinnamoyl group, a chalcone group or a coumarin group. )

(In General Formula (2), X ¹ , Y, and X ² represent the same group as the group represented by General Formula (1). R ³ and R ⁴ are each independently a hydrogen atom, Halogen atom, hydroxyl group, nitro group, sulfonic acid group, sulfonate group, halogenated methyl group, cyano group, amino group, formyl group, carboxyl group, piperidino group, and general formula (3)

(Wherein R ⁵ represents a hydrogen atom, an alkyl group, a cycloalkyl group, a phenyl group, a piperidino group; and an alkyl group, a cycloalkyl group, a phenyl group, an alkoxyl group, a cycloalkoxyl group, or a phenoxy group bonded to these groups. Represents one or more groups selected from the group consisting of: The optical film according to claim 1, wherein the photo-alignment layer (A) does not contain a photopolymerization initiator. ^3. The optical film according to claim 1, wherein the dichroic dye having the polymerizable group or the dichroic dye has a mass average molecular weight of 1 × 10 ^{2 to} 5 × 10 ³ . The optical film according to claim 1, further comprising an optically isotropic resin layer between the two adjacent optically anisotropic layers. At least one of the plurality of optically anisotropic layers is a first optically anisotropic layer having a retardation measured at a wavelength of 540 nm of 240 to 300 nm, and at least one of the plurality of optically anisotropic layers. The optical film according to claim 1, wherein one is a second optical anisotropic layer having a phase difference of 120 to 150 nm measured at a wavelength of 540 nm. The optically anisotropic layer is an optically anisotropic layer having a function of a half-wave plate and an optically anisotropic layer having a function of a quarter-wave plate. Optical film. The optical film according to claim 1, wherein a stacking angle error of the plurality of optically anisotropic layers is within ± 0.1 °. It is a manufacturing method of the optical film in any one of Claims 1-7, Comprising: The compound which has a photo-alignment group and a polymeric group on a board | substrate, or a compound and a polymerizable compound which have a photo-alignment group are contained. And a step a in which a photoalignable polymerizable composition layer not coated with a photopolymerization initiator is applied and dried to form a photoalignable polymerizable composition layer, and polarized light having a wavelength that can be absorbed by the photoalignable group or A step b of imparting liquid crystal alignment ability by irradiating the substrate with non-polarized light from an oblique direction; a step c of forming a polymerizable liquid crystal composition layer containing a liquid crystal compound having a polymerizable group on the layer; The step (I) comprising repeating the steps (I) of the two laminated layers in this order with the step d of simultaneously polymerizing the polymerizable groups of the two layers by active energy rays or heat is repeated a plurality of times. A method for producing an optical film. The manufacturing method of the optical film of Claim 8 which has the process e of apply | coating and drying an optically isotropic resin layer between the process (I) performed several times. An elliptically polarizing plate comprising the optical film according to claim 1 and a polarizing plate. A circularly polarizing plate comprising the optical film according to claim 1 and a polarizing plate. A liquid crystal display element using the optical film according to claim 1.

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