Optically absorbing anisotropic film, three-dimensional optically absorbing anisotropic film, and manufacturing method thereof

Abstract

To provide a light absorption anisotropic film that adds a more effective peeking prevention function.SOLUTION: Provided is a light absorption anisotropic film that contains a dichroic dye and a liquid crystal compound, the light absorbance of which satisfies formulas (1), (2) and (3) below. Formula (1): Az>(Ax+Ay) / 2; formula (2): Ax(z=60) / Ax>5; formula (3): Ay(z=60) / Ay>5. (Ax, Ay, Az, Ax(z=60) and Ay(z=60) represent the absorbance of the dichroic dye in absorption maximum wavelength, Ax representing the light absorbance of linearly polarized light that oscillates in the direction of axis x, Ay representing the light absorbance of linearly polarized light that oscillates in the direction of axis y, Az representing the light absorbance of linearly polarized light that oscillates in the direction of axis z, Ax(z=60) representing the light absorbance of linearly polarized light that oscillates in the direction of axis x when the film is rotated 60° around the axis y, Ay(z=60) representing the light absorbance of linearly polarized light that oscillates in the direction of axis y when the film is rotated 60° around the axis x.)SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optically absorptive anisotropic film, a three-dimensional optically absorptive anisotropic film, and a method for producing the same. [Background technology]

[0002] Patent Document 1 describes a polarizing plate having a polarizing layer with a K value, defined as K=(kx-kz) / (kx-ky), of 0.25 to 0.75. (The x-axis and y-axis are the mutually perpendicular axes in the plane of the polarizing layer, and the z-axis is the axis perpendicular to the xy-axis plane, and kx, ky, and kz are the absorption coefficients in the x-axis, y-axis, and z-axis directions, respectively.) That is, the polarizing plate satisfies the relationships kx>kz>ky and K=0.25 to 0.75, and in this polarizing plate, the dichroic dye is oriented at an angle with respect to the film surface. Specifically, a polarizing plate containing the following liquid crystal compounds 1 and 2 and black dichroic dye S-344 manufactured by Mitsui Toatsu Co., Ltd. was prepared, and a polarizing plate containing a polarizing layer with values ​​of kx=0.111, ky=0.001, and kz=0.059 was obtained. TIFF0007774654000001.tif70110 [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-033050 Summary of the Invention [Problem to be solved by the invention]

[0004] The polarizing film described above had problems with insufficient vertical alignment order, resulting in insufficient transmission of light from the front and absorption of light from oblique angles. Therefore, there was a need for a thin, easily manufactured, optically absorbing anisotropic film that could provide more effective anti-peeping functionality to displays of mobile phones, bank ATMs, etc. [Means for solving the problem]

[0005] The present invention includes the following inventions. [1] An optically absorptive anisotropic film containing a dichroic dye and a liquid crystalline compound, wherein the optical absorbance of the film satisfies the following formulas (1), (2), and (3), where any direction in the film plane is the x-axis, the direction in the film plane perpendicular to the x-axis is the y-axis, and the film thickness direction perpendicular to the x-axis and y-axis is the z-axis. Az>(Ax+Ay) / 2 (1) Ax(z=60) / Ax>5 (2) Ay(z=60) / Ay>5 (3) (Ax, Ay, Az, Ax(z=60), and Ay(z=60) are all absorbances at the absorption maximum wavelength of the dichroic dye in the optically absorptive anisotropic film, Ax represents the absorbance of linearly polarized light oscillating in the x-axis direction, Ay represents the absorbance of linearly polarized light vibrating in the y-axis direction, Az represents the absorbance of linearly polarized light vibrating in the z-axis direction, Ax(z=60) represents the absorbance of linearly polarized light oscillating in the x-axis direction when the film is rotated 60° around the y-axis, Ay (z=60) represents the absorbance of linearly polarized light oscillating in the y-axis direction when the film is rotated 60° around the x-axis. [2] The optically absorptive anisotropic film according to [1], wherein the liquid crystalline compound forms a smectic liquid crystal phase. [3] The optically absorptive anisotropic film according to [1] or [2], wherein the liquid crystalline compound forms a high-order smectic liquid crystal phase. [4] The optically absorptive anisotropic film according to any one of [1] to [3], which exhibits a Bragg peak in X-ray diffraction measurement. [5] The optically absorptive anisotropic film according to any one of [1] to [4], wherein the dichroic dye in the optically absorptive anisotropic film has a maximum absorption wavelength in the wavelength range of 500 nm to 600 nm. [6] The optically absorptive anisotropic film according to any one of [1] to [5], which satisfies the formulae (4) and (5). Ax(z=60) / Ax>10 (4) Ay(z=60) / Ay>10 (5) [7] The optically absorptive anisotropic film according to any one of [1] to [6], which contains at least three kinds of dichroic dyes having different maximum absorption wavelengths. [8] The optically absorptive anisotropic film according to any one of [1] to [7], wherein the film thickness of the optically absorptive anisotropic film is 5 μm or less. [9] An optical film comprising the optically absorptive anisotropic film according to any one of [1] to [8] and a substrate.

[10] The optical film according to [9], which does not include an alignment film between the substrate and the optically absorptive anisotropic film.

[11] The method for producing an optical film according to [9] or

[10] , comprising carrying out the following steps (1) to (4) in this order: (1) A step of applying a composition containing a liquid crystal compound, a dichroic dye, and a solvent to a substrate to form a coating film. (2) A process of removing the solvent from the coating film to form a dry film. (3) A step of cooling the dried film to develop a liquid crystal phase. (4) A step of curing the liquid crystal compound by irradiating it with active energy rays.

[12] The method according to

[11] , in which a long film is used as the substrate and an optical film is continuously produced.

[13] A three-dimensional optically absorptive anisotropic film obtained by laminating the optically absorptive anisotropic film according to any one of [1] to [8] and a horizontal polarizing film, wherein the three-dimensional optically absorptive anisotropic film satisfies the following formula (4) when the absorption axis of the horizontal polarizing film is the x'-axis, the transmission axis of the horizontal polarizing film is the y'-axis, and the axis perpendicular to the x'-axis and y'-axis is the z'-axis. Ax'>Az'>Ay' (6) (Ax', Ay', and Az' are all absorbances at the absorption maximum wavelength of the dichroic dye in the optically absorptive anisotropic film, Ax' represents the absorbance of linearly polarized light vibrating in the x' direction, Ay' represents the absorbance of linearly polarized light vibrating in the y' direction, Az' represents the absorbance of linearly polarized light vibrating in the z' direction.)

[14] The three-dimensional optically absorptive anisotropic film according to

[13] , wherein the horizontal polarizing film contains polyvinyl alcohol and a dichroic dye.

[15] The three-dimensional optically absorptive anisotropic film according to

[13] , wherein the horizontal polarizing film contains a dichroic dye and a liquid crystalline compound, or contains a dichroic dye having liquid crystal properties.

[16] The three-dimensional optically absorptive anisotropic film according to any one of

[13] to

[15] , wherein the optically absorptive anisotropic film is laminated on a horizontal polarizing film via a pressure-sensitive adhesive or adhesive. [Effects of the Invention]

[0006] According to the present invention, it is possible to obtain a thin, easily manufactured optically absorptive anisotropic film that provides a function of adequately preventing peeping on the displays of mobile phones, bank ATMs, and the like. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of the optically absorptive anisotropic film. [Figure 2] 1 is a schematic diagram of a method for producing an optically absorptive anisotropic film. [Figure 3] FIG. 1 is a perspective view of an example of a three-dimensional optically absorptive anisotropic film. [Figure 4] FIG. 1 is a perspective view of a liquid crystal display device having a three-dimensional optically absorptive anisotropic film. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Light-absorbing anisotropic film> The optically absorptive anisotropic film is a film containing a dichroic dye. The optically absorptive anisotropic film of the present invention contains a dichroic dye and a liquid crystal compound.

[0009] The optically absorptive anisotropic film satisfies all of the following formulas (1), (2), and (3), where an arbitrary direction in the film plane is the x-axis, a direction perpendicular to the x-axis in the film plane is the y-axis, and a film thickness direction perpendicular to the x-axis and y-axis is the z-axis (see Figure 1). Az>(Ax+Ay) / 2 (1) Ax(z=60) / Ax>5 (2) Ay(z=60) / Ay>5 (3) Here, Ax, Ay, Az, Ax(z=60), and Ay(z=60) are all absorbances at the maximum absorption wavelengths of the dichroic dyes in the optically absorptive anisotropic film. Ax represents the absorbance of linearly polarized light oscillating in the x-axis direction. Ax can be measured by incident linearly polarized light oscillating in the x-axis direction toward the film surface from the z-axis direction. Ay represents the absorbance of linearly polarized light oscillating in the y-axis direction. Ay can be measured by incident linearly polarized light oscillating in the y-axis direction toward the film surface from the z-axis direction. Az represents the absorbance of linearly polarized light oscillating in the z-axis direction. Az can be measured, for example, by incident linearly polarized light oscillating in the z-axis direction toward the side of the film from the xy plane, i.e., perpendicular to the side (thickness direction) of the film when the film is considered to be an xy plane. Ax(z=60) represents the absorbance of linearly polarized light oscillating in the x-axis direction when the film is rotated 60° around the y-axis. Ax(z=60) can be measured by incident the same linearly polarized light as that used to measure Ax, with the film rotated 60° around the y-axis. Here, the film is rotated by rotating the film in the state where Ax was measured by 60° around the y-axis as the axis of rotation in the direction of incidence of linearly polarized light. Ay(z=60) represents the absorbance of linearly polarized light oscillating in the y-axis direction when the film is rotated by 60° around the x-axis as the axis of rotation. Ay(z=60) can be measured by rotating the film by 60° around the x-axis as the axis of rotation and then incident with the same linearly polarized light as that used to measure Ay. Here, the film is rotated by rotating the film in the state where Ay was measured by 60° around the x-axis as the axis of rotation in the direction of incidence of linearly polarized light.

[0010] The absorbance in the z direction in equation (1) is difficult to measure because light is incident from the side of the film. Therefore, when the angle between the vibration plane of the linearly polarized light (measurement light) and the xy plane of the film is 90°, the absorbance in the Az direction can be estimated by measuring while tilting the xy plane of the film 30° and 60° from this vibration plane toward the incident direction of the linearly polarized light. Specifically, it can be estimated using the following methods. With the film rotated by 30° and 60° about the y-axis as the rotation axis, Ax(z = 30) and Ax(z = 60) are measured by incident linearly polarized light identical to the linearly polarized light for which Ax was measured. Similarly, with the film rotated by 30° and 60° about the x-axis as the rotation axis, Ay(z = 30) and Ay(z = 60) are measured by incident linearly polarized light identical to the linearly polarized light for which Ay was measured. At this time, if Ax(z = 30) < Ax(z = 60) and Ay(z = 30) = Ay(z = 60), then Ax(z = 30) < Ax(z = 60) < Ax(z = 90) = Az, and if Ay(z = 30) < Ay(z = 60) and Ax(z = 30) = Ax(z = 60), then Ay(z = 30) < Ay(z = 60) < Ay(z = 90) = Az. Thus, it can be said that it necessarily satisfies formula (1).

[0011] In particular, when there is no absorption anisotropy in the x - y plane, that is, when Ax and Ay are equal, since Ax(z = 30) = Ay(z = 30) and Ax(z = 60) = Ay(z = 60), Ax(z = 30) and Ay(z = 30) can be denoted as A(z = 30), and Ax(z = 60) and Ay(z = 60) can be denoted as A(z = 60). That is, if A(z = 30) < A(z = 60), it satisfies the relationship of A(z = 30) < A(z = 60) < A(z = 90) = Az. Furthermore, if A(z = 30) > (Ax + Ay) / 2, it can be said that necessarily Az satisfies formula (1).

[0012] The light absorption anisotropic film of the present invention satisfies the above formulas (2) and (3). Ax(z = 60) / Ax and Ay(z = 60) / Ay mean that the larger their numerical values, the better the light absorption anisotropy is shown. These numerical values may be, for example, 50 or less, or may be 30 or less. Also, the light absorption anisotropic film of the present invention preferably satisfies formulas (4) and (5). Ax(z = 60) / Ax > 10 (4) Ay(z = 60) / Ay > 10 (5)

[0013] When the optically absorptive anisotropic film satisfies the formulas (1), (2), and (3), the dichroic dye can be said to have excellent absorption anisotropy, i.e., excellent polarization performance. This excellent property allows the film to effectively transmit light from the front direction and effectively absorb light from oblique directions.

[0014] The thickness of the optically absorptive anisotropic film is preferably 0.1 to 10 μm, more preferably 1 to 5 μm. If the thickness of the optically absorptive anisotropic film is less than 0.1 μm, the absorption of light from oblique directions is weak, and good anti-peeping properties cannot be obtained. If the thickness is 10 μm or more, the orientation of the dichroic dye is disturbed, resulting in a problem of reduced transmission properties in the front direction.

[0015] <Dichroic dye> A dichroic dye is a dye that has different absorbance in the direction of the long axis of the molecule and in the direction of the short axis.

[0016] The dichroic dye preferably has an absorption maximum wavelength (λMAX) in the optically absorptive anisotropic film of the present invention in the range of 300 to 700 nm, and more preferably in the range of 500 to 600 nm. By having an absorption maximum wavelength in the range of 500 to 600 nm, where human visual sensitivity is high, peeping can be more effectively prevented. In other words, using a dichroic dye having an absorption maximum at a wavelength where human visual sensitivity is high allows the amount of dichroic dye used to be reduced and the optically absorptive anisotropic film to be made thinner. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, with azo dyes being preferred. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, with bisazo dyes and trisazo dyes being preferred. The dichroic dyes may be used alone or in combination; however, when polarization properties are required across the entire visible light range, it is preferable to combine three or more dichroic dyes, and it is more preferable to combine three or more azo dyes. When multiple dichroic dyes are combined, it is preferable that at least one of them has a maximum absorption wavelength in the wavelength range of 500 to 600 nm in the present optically absorptive anisotropic film. When two dichroic dyes are combined, it is preferable that one of them has a maximum absorption wavelength in the range of 350 to 499 nm or 601 to 750 nm. When three dichroic dyes are combined, it is preferable that one of them has a maximum absorption wavelength in the range of 350 to 499 nm, 500 to 600 nm, and 601 to 750 nm, respectively. By combining them in this way, peeping can be more effectively prevented.

[0017] Examples of azo dyes include compounds represented by formula (2) (hereinafter sometimes referred to as "compound (2)"). A 1 (-N=NA 2 ) p -N=NA 3 (2) [In formula (2), A 1 and A 3 A each independently represents a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a monovalent heterocyclic group which may have a substituent. 2 represents an optionally substituted 1,4-phenylene group, an optionally substituted naphthalene-1,4-diyl group, or an optionally substituted divalent heterocyclic group. p represents an integer of 1 to 4. When p is an integer of 2 or more, a plurality of A 2 may be the same or different.]

[0018] Examples of monovalent heterocyclic groups include groups in which one hydrogen atom has been removed from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of divalent heterocyclic groups include groups in which two hydrogen atoms have been removed from the above heterocyclic compounds.

[0019] A 1 and A 3Phenyl, naphthyl and monovalent heterocyclic groups in the above formula, and A 2 Examples of the substituents that the 1,4-phenylene group, naphthalene-1,4-diyl group, and divalent heterocyclic group in the formula (I) may optionally have include alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, and butyl; alkoxy groups having 1 to 4 carbon atoms, such as methoxy, ethoxy, and butoxy; fluorinated alkyl groups having 1 to 4 carbon atoms, such as trifluoromethyl; cyano group; nitro group; halogen atoms, such as chlorine and fluorine; and substituted or unsubstituted amino groups, such as amino, diethylamino, and pyrrolidino (a substituted amino group refers to an amino group having one or two alkyl groups having 1 to 6 carbon atoms, or an amino group in which two substituted alkyl groups are bonded to form an alkanediyl group having 2 to 8 carbon atoms. An unsubstituted amino group is -NH). ) are included. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and a hexyl group. Examples of the alkanediyl group having 2 to 8 carbon atoms include an ethylene group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, and an octane-1,8-diyl group.

[0020] Among the compounds (2), the compounds represented by the following formulas (2-1) to (2-6) are preferred.

[0021] TIFF0007774654000002.tif83109

[0022] TIFF0007774654000003.tif74127 [In formulas (2-1) to (2-6), B 1 ~B 20 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of a substituted amino group and an unsubstituted amino group are as defined above), a chlorine atom, or a trifluoromethyl group. n1 to n4 each independently represent an integer of 0 to 3. If n1 is 2 or more, multiple B 2 may be the same or different, If n2 is 2 or more, multiple B 6 may be the same or different, If n3 is 2 or more, multiple B 9 may be the same or different, If n4 is 2 or more, multiple B 14 may be the same or different.]

[0023] The anthraquinone dye is preferably a compound represented by formula (2-7). TIFF0007774654000004.tif3179 [In formula (2-7), R 1 ~R 8 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.]

[0024] The oxazine dye is preferably a compound represented by formula (2-8). TIFF0007774654000005.tif3177 [In formula (2-8), R 9 ~R 15 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.]

[0025] The acridine dye is preferably a compound represented by formula (2-9). TIFF0007774654000006.tif3171 [In formula (2-9), R 16 ~R 23 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.]

[0026] R in formula (2-7), formula (2-8) and formula (2-9) x Examples of the alkyl group having 1 to 4 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a toluyl group, a xylyl group, and a naphthyl group.

[0027] As the cyanine dye, compounds represented by formula (2-10) and compounds represented by formula (2-11) are preferred. TIFF0007774654000007.tif1555 [In formula (2-10), D 1 and D 2 each independently represents a group represented by any one of formulas (2-10a) to (2-10d). TIFF0007774654000008.tif27128 n5 represents an integer from 1 to 3.

[0028] TIFF0007774654000009.tif1856 [In formula (2-11), D 3 and D 4 represent, independently of each other, a group represented by any one of formulas (2-11a) to (2-11h). TIFF0007774654000010.tif64110 n6 represents an integer from 1 to 3.

[0029] From the viewpoint of improving the alignment of the dichroic dye, the content of the dichroic dye in the optically absorptive anisotropic film is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.1 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the solid content of the optically absorptive anisotropic composition. If the content of the dichroic dye is within this range, it is preferable because the liquid crystal alignment of the liquid crystalline compound is unlikely to be disturbed.

[0030] <Base material> The present optically absorptive anisotropic film can be formed by a method such as coating a composition containing a dichroic dye (hereinafter, sometimes referred to as the present optically absorptive anisotropic composition) on a substrate. The substrate may be a glass substrate or a resin substrate, but is preferably a resin substrate. When the resin substrate is transferred and not peeled off, a transparent resin substrate is preferred. The transparent resin substrate means a substrate having translucency that allows light, particularly visible light, to pass through, and translucency refers to a property that provides a luminosity-corrected transmittance of 80% or more for light rays with wavelengths of 380 nm to 780 nm.

[0031] Examples of resins constituting the substrate include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; polyphenylene sulfide; and polyphenylene oxide. Preferred are cellulose esters, cyclic olefin-based resins, polycarbonate, polyethersulfone, polyethylene terephthalate, and polymethacrylic acid esters.

[0032] Cellulose esters are cellulose esters in which at least a portion of the hydroxyl groups contained in cellulose has been esterified, and are commercially available. Substrates containing cellulose esters are also commercially available. Examples of commercially available substrates containing cellulose esters include Fujitac (registered trademark) Film (Fujifilm Corporation), KC8UX2M (Konica Minolta Opto, Inc.), KC8UY (Konica Minolta, Inc.), and KC4UY (Konica Minolta Opto, Inc.).

[0033] The cyclic olefin resin includes a polymer of a cyclic olefin such as norbornene or a polycyclic norbornene monomer, or a copolymer thereof. The cyclic olefin resin may include a ring-open structure, or may be a hydrogenated cyclic olefin resin including a ring-open structure. The cyclic olefin resin may also include structural units derived from a chain olefin and a vinylated aromatic compound, to the extent that the transparency is not significantly impaired and the moisture absorption is not significantly increased. The cyclic olefin resin may also have a polar group introduced into its molecule. Examples of the chain olefin include ethylene and propylene, and examples of the vinylated aromatic compound include styrene, α-methylstyrene, and alkyl-substituted styrene.

[0034] When the cyclic olefin resin is a copolymer of a cyclic olefin and a chain olefin or a vinylated aromatic compound, the content of structural units derived from the cyclic olefin is usually 50 mol % or less, and preferably 15 to 50 mol %, based on the total structural units of the copolymer. When the cyclic olefin resin is a terpolymer of a cyclic olefin, a chain olefin, and a vinylated aromatic compound, the content of structural units derived from the chain olefin is usually 5 to 80 mol% relative to the total structural units of the copolymer, and the content of structural units derived from the vinylated aromatic compound is usually 5 to 80 mol% relative to the total structural units of the copolymer. Such a terpolymer has the advantage that the amount of expensive cyclic olefin used can be relatively reduced.

[0035] Cyclic olefin resins are commercially available. Examples of commercially available cyclic olefin resins include Topas (registered trademark) (Ticona GmbH, Germany), Arton (registered trademark) (JSR Corporation), ZEONOR (registered trademark) (ZEON Corporation), ZEONEX (registered trademark) (ZEON Corporation), and APEL (registered trademark) (Mitsui Chemicals, Inc.). Such cyclic olefin resins can be formed into a film by known means such as solvent casting or melt extrusion to form a substrate. Examples of commercially available substrates containing cyclic olefin resins include S-Cina (registered trademark) (Sekisui Chemical Co., Ltd.), SCA40 (registered trademark) (Sekisui Chemical Co., Ltd.), ZEONORFILM (registered trademark) (Optes Co., Ltd.), and ArtonFILM (registered trademark) (JSR Corporation).

[0036] The substrate may be subjected to a surface treatment. Examples of the surface treatment method include a method of treating the substrate surface with corona or plasma under an atmosphere from vacuum to atmospheric pressure, a method of laser treating the substrate surface, a method of ozone treating the substrate surface, a method of saponifying the substrate surface, a method of flame treating the substrate surface, a method of applying a coupling agent to the substrate surface, a method of primer treating the substrate surface, and a graft polymerization method in which a reactive monomer or a reactive polymer is attached to the substrate surface and then irradiated with radiation, plasma, or ultraviolet light to cause a reaction. Among these, a method of treating the substrate surface with corona or plasma under an atmosphere from vacuum to atmospheric pressure is preferred.

[0037] Methods for performing surface treatment of a substrate with corona or plasma include a method in which the substrate is placed between opposing electrodes under pressure near atmospheric pressure and corona or plasma is generated to perform surface treatment of the substrate; a method in which a gas is flowed between opposing electrodes, the gas is converted into plasma between the electrodes, and the plasma gas is sprayed onto the substrate; and a method in which glow discharge plasma is generated under low-pressure conditions to perform surface treatment of the substrate.

[0038] Among these, a method of placing a substrate between opposing electrodes under a pressure close to atmospheric pressure and generating a corona or plasma to perform surface treatment of the substrate, or a method of flowing a gas between opposing electrodes, converting the gas into plasma between the electrodes, and spraying the plasma gas onto the substrate are preferred. Such corona or plasma surface treatment is usually performed using a commercially available surface treatment device.

[0039] The substrate may have a protective film on the surface opposite to the surface on which the optically absorptive anisotropic composition is applied. Examples of the protective film include films of polyethylene, polyethylene terephthalate, polycarbonate, polyolefin, etc., and films further comprising an adhesive layer. Among these, polyethylene terephthalate is preferred because it has little thermal deformation during drying. By having a protective film on the surface opposite to the surface on which the optically absorptive anisotropic composition is applied, it is possible to suppress shaking of the film and slight vibration of the coating surface during transport of the substrate, thereby improving the uniformity of the coating film.

[0040] The thickness of the substrate is preferably thin in terms of the weight being practically manageable, but if it is too thin, the strength decreases and the processability tends to be poor. The thickness of the substrate is usually 5 to 300 μm, and preferably 20 to 200 μm.

[0041] The length of the substrate in the longitudinal direction is usually 10 to 3000 m, preferably 100 to 2000 m, and the length of the substrate in the lateral direction is usually 0.1 to 5 m, preferably 0.2 to 2 m.

[0042] <Liquid crystal compounds> The optically absorptive anisotropic film of the present invention is a liquid crystal cured film containing a dichroic dye and a liquid crystalline compound. The liquid crystal compound contained in the present optically absorptive anisotropic film is preferably a polymerizable liquid crystal compound. The polymerizable liquid crystal compound is a compound that has a polymerizable group and has liquid crystal properties. The polymerizable group refers to a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical or acid generated from a photopolymerization initiator, which will be described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The liquid crystal compound may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase order structure of the thermotropic liquid crystal may be a nematic liquid crystal or a smectic liquid crystal. A compound that forms a smectic liquid crystal phase is preferred, and a compound that forms a higher-order smectic liquid crystal phase such as a smectic B phase is more preferred. When the liquid crystal phase formed by the liquid crystal compound is a higher-order smectic phase, a light absorption anisotropic film with a higher degree of orientational order can be produced. Increasing the degree of orientational order tends to increase the values ​​of Ax(z=60) / Ax and Ay(z=60) / Ay.

[0043] As the polymerizable liquid crystal compound, a smectic liquid crystal compound is preferred because it can provide higher polarization performance, and a higher-order smectic liquid crystal compound is more preferred. Among these, a higher-order smectic liquid crystal compound that forms a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, or a smectic L phase is more preferred, and a higher-order smectic liquid crystal compound that forms a smectic B phase, a smectic F phase, or a smectic I phase is more preferred. When the liquid crystal phase formed by the polymerizable liquid crystal compound is one of these higher-order smectic phases, a liquid crystal cured film with a higher degree of orientational order can be produced, resulting in high polarization performance. Furthermore, such a liquid crystal cured film with a high degree of orientational order exhibits Bragg peaks derived from a higher-order structure, such as a hexatic phase or a crystalline phase, in X-ray diffraction measurement. The Bragg peak is a peak derived from the periodic structure of molecular orientation, and a film having a periodic interval of 3.0 to 6.0 Å can be obtained. Specific examples of such smectic liquid crystal compounds include compounds represented by the following formula (1) (hereinafter, sometimes referred to as compound (1)). The polymerizable liquid crystal compounds may be used alone or in combination.

[0044] U 1 -V 1 -W 1 -X 1 -Y 1 -X 2 -Y 2 -X 3 -W 2 -V 2 -U 2 (1) [In formula (1), X 1 , X 2 and X 3 each independently represents an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group, provided that X 1 , X 2 and X 3At least one of them is a 1,4-phenylene group which may have a substituent. The -CH2- constituting the cyclohexane-1,4-diyl group may be replaced by -O-, -S- or -NR-. R represents an alkyl group having 1 to 6 carbon atoms or a phenyl group. Y 1 and Y 2 are, independently of each other, -CH2CH2-, -CH2O-, -COO-, -OCOO-, a single bond, -N=N-, -CR a =CR b -, -C≡C- or CR a =N-. R a and R b are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. U 1 represents a hydrogen atom or a polymerizable group. U 2 represents a polymerizable group. W 1 and W 2 represent, independently of one another, a single bond, —O—, —S—, —COO— or —OCOO—. V 1 and V 2 represent, independently of each other, an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH2- constituting the alkanediyl group may be replaced by -O-, -S- or -NH-.

[0045] In compound (1), X 1 , X 2 and X 3 At least one of these is preferably a 1,4-phenylene group which may have a substituent. The 1,4-phenylene group which may have a substituent is preferably unsubstituted. The cyclohexane-1,4-diyl group which may have a substituent is preferably a trans-cyclohexane-1,4-diyl group which may have a substituent, and the trans-cyclohexane-1,4-diyl group which may have a substituent is preferably unsubstituted.

[0046] Examples of the substituent that the optionally substituted 1,4-phenylene group or the optionally substituted cyclohexane-1,4-diyl group may optionally have include alkyl groups having 1 to 4 carbon atoms such as a methyl group, an ethyl group, and a butyl group; a cyano group; and halogen atoms such as a chlorine atom and a fluorine atom.

[0047] Y 1 is preferably -CH2CH2-, -COO- or a single bond, and Y 2 is preferably —CH2CH2— or —CH2O—.

[0048] U 2 is a polymerizable group. 1 is a hydrogen atom or a polymerizable group, preferably a polymerizable group. 1 and U 2 Preferably, both of are polymerizable groups, and more preferably, both are photopolymerizable groups. A polymerizable liquid crystal compound having a photopolymerizable group is advantageous in that it can be polymerized under lower temperature conditions.

[0049] U 1 and U 2 The polymerizable groups represented by the formula (I) may be different from each other, but are preferably the same. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

[0050] V 1 and V 2 Examples of the alkanediyl group represented by the formula (V) include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a decane-1,10-diyl group, a tetradecane-1,14-diyl group, and an icosane-1,20-diyl group.1 and V 2 is preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably an alkanediyl group having 6 to 12 carbon atoms. Examples of the substituent that the optionally substituted alkanediyl group having 1 to 20 carbon atoms may have include a cyano group and a halogen atom such as a chlorine atom or a fluorine atom. However, the alkanediyl group is preferably unsubstituted, and more preferably an unsubstituted, linear alkanediyl group.

[0051] Preferably, W 1 and W 2 are each independently a single bond or O—.

[0052] Specific examples of compound (1) include compounds represented by formulas (1-1) to (1-23). ​​When compound (1) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably a trans-type.

[0053] TIFF0007774654000011.tif155139

[0054] TIFF0007774654000012.tif91136

[0055] TIFF0007774654000013.tif89144

[0056] TIFF0007774654000014.tif84144

[0057] Among the exemplified compounds (1), at least one selected from the group consisting of compounds represented by formula (1-2), formula (1-3), formula (1-4), formula (1-6), formula (1-7), formula (1-8), formula (1-13), formula (1-14) and formula (1-15) is preferred.

[0058] The exemplified compounds (1) can be used alone or in combination in the liquid crystal cured film. Furthermore, when two or more polymerizable liquid crystal compounds are combined, it is preferable that at least one of them is compound (1), and more preferably two or more of them are compound (1). By combining them, liquid crystallinity may be temporarily maintained even at temperatures below the liquid crystal-crystalline phase transition temperature. When two polymerizable liquid crystal compounds are combined, the mixing ratio is usually 1:99 to 50:50, preferably 5:95 to 50:50, and more preferably 10:90 to 50:50. When two polymerizable liquid crystal compounds are combined and only one of them is compound (1), it is preferable that compound (1) be blended so that it accounts for a higher proportion in the above mixing ratio.

[0059] The polymerizable liquid crystal compound can be produced by a known method, for example, as described in Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996) and Japanese Patent No. 4719156.

[0060] From the viewpoint of enhancing the alignment of the liquid crystal compound, the content of the liquid crystal compound in the optically absorptive anisotropic film is usually 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 80 to 94 parts by mass, and even more preferably 80 to 90 parts by mass, relative to 100 parts by mass of the optically absorptive anisotropic film. The content of the liquid crystal compound in the optically absorptive anisotropic film can be calculated as the ratio of the liquid crystal compound to 100 parts by mass of the solid content of the optically absorptive anisotropic composition that forms the optically absorptive anisotropic film.

[0061] <Polymerization initiator> The optically absorptive anisotropic composition may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound, etc. As the polymerization initiator, a photopolymerization initiator that generates active radicals by the action of light is preferred.

[0062] Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, and sulfonium salts.

[0063] Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

[0064] Examples of the benzophenone compound include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone.

[0065] Examples of alkylphenone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one.

[0066] Examples of the acylphosphine oxide compound include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0067] Examples of the triazine compound include 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, and 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl]-1,3,5-triazine. 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, and 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine.

[0068] The polymerization initiator may be commercially available. Examples of commercially available polymerization initiators include Irgacure (registered trademark) 907, 184, 651, 819, 250, and 369 (BASF); Seikuol (registered trademark) BZ, Z, and BEE (Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (Nippon Kayaku Co., Ltd.); Adeka Optomer SP-152 and SP-170 (ADEKA Corporation); TAZ-A and TAZ-PP (DKSH Japan Co., Ltd.); and TAZ-104 (Sanwa Chemical Co., Ltd.).

[0069] The content of the polymerization initiator is usually 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound, from the viewpoint of preventing the alignment of the polymerizable liquid crystal compound from being disturbed.

[0070] <Leveling agent> The optically absorptive anisotropic film may contain a leveling agent. The leveling agent has the function of adjusting the fluidity of the optically absorptive anisotropic composition and making the optically absorptive anisotropic film flatter, and examples thereof include surfactants. Preferred leveling agents include those containing a polyacrylate compound as a main component and those containing a fluorine atom-containing compound as a main component.

[0071] Examples of leveling agents containing a polyacrylate compound as a main component include BYK-350, BYK-352, BYK-353, BYK-354, BYK-355, BYK-358N, BYK-361N, BYK-380, BYK-381, and BYK-392 (BYK Chemie).

[0072] Examples of leveling agents containing a fluorine atom-containing compound as a main component include Megafac (registered trademark) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-470, F-471, F-477, F-479, F-482, and F-483 (DIC Corporation); Surflon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH-40, and SA-100 (AGC Seimi Chemical Co., Ltd.); E1830 and E5844 (Daikin Industries, Ltd.); and F-top EF301, EF303, EF351, and EF352 (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

[0073] The content of the leveling agent in the optically absorptive anisotropic film is usually 0.01 to 5 parts by mass, and preferably 0.1 to 3 parts by mass, per 100 parts by mass of the liquid crystal compound. When the content of the leveling agent is within the above range, the resulting liquid crystal cured film tends to be smoother, which is preferable. When the content of the leveling agent relative to the liquid crystal compound exceeds the above range, the resulting liquid crystal cured film tends to be uneven or tends to be aligned in the horizontal direction, which is undesirable. The optically absorptive anisotropic film may contain two or more types of leveling agents.

[0074] <Solvent> The optically absorptive anisotropic composition used to form the optically absorptive anisotropic film may contain a solvent. When the liquid crystal compound is contained, the solvent is preferably one that can completely dissolve the liquid crystal compound, and when the liquid crystal compound is a polymerizable liquid crystal compound, the solvent is preferably one that is inert to the polymerization reaction.

[0075] Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene, and nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; and chlorine-containing solvents such as chloroform and chlorobenzene. These solvents may be used alone or in combination.

[0076] The content of the solvent is preferably 50 to 98 mass % relative to the total amount of the optically absorptive anisotropic composition, in other words, the proportion of the optically absorptive anisotropic film components is preferably 2 to 50 mass % relative to the total amount of the optically absorptive anisotropic composition. When the solid content is 50% by mass or less relative to the total amount of the optically absorptive anisotropic composition, the viscosity of the optically absorptive anisotropic composition is low, and therefore the thickness of the liquid crystal cured film becomes approximately uniform, and the liquid crystal cured film tends to be less prone to unevenness. In addition, such solid content can be determined in consideration of the thickness of the liquid crystal cured film to be produced.

[0077] <Alignment film> The optical film having an optically absorptive anisotropic film and a substrate may include an alignment film between the substrate and the optically absorptive anisotropic film. The alignment film in the present invention has an alignment regulating force for aligning a dichroic dye or a liquid crystal compound in a direction perpendicular to the substrate. The alignment film preferably has solvent resistance so that the optically absorptive anisotropic composition does not dissolve when applied, and also has heat resistance to remove the solvent and heat treatment for aligning the liquid crystal compound. Examples of such alignment films include alignment films containing an orienting polymer, and photoalignment films.

[0078] <Alignment film containing alignment polymer> Examples of the oriented polymer include polyamides and gelatins having an amide bond in the molecule, polyimides having an imide bond in the molecule, and their hydrolyzed products such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Among these, polyvinyl alcohol is preferred. Two or more oriented polymers may be used in combination.

[0079] An alignment film containing an alignment polymer is usually formed on the surface of a substrate by applying a composition in which an alignment polymer is dissolved in a solvent (hereinafter referred to as an alignment polymer composition) to the substrate and then removing the solvent, or by applying an alignment polymer composition to the substrate, removing the solvent, and then rubbing the substrate (rubbing method).

[0080] Examples of the solvent include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether, ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone, aliphatic hydrocarbon solvents such as pentane, hexane, and heptane, aromatic hydrocarbon solvents such as toluene and xylene, nitrile solvents such as acetonitrile, ether solvents such as tetrahydrofuran and dimethoxyethane, and chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents may be used alone or in combination of two or more.

[0081] The concentration of the orienting polymer in the orienting polymer composition may be within a range in which the orienting polymer material can be completely dissolved in the solvent, but is preferably 0.1 to 20 mass % in terms of solid content relative to the solution, and more preferably approximately 0.1 to 10 mass %.

[0082] As the oriented polymer composition, commercially available alignment film materials may be used as they are. Examples of commercially available alignment film materials include SUNEVER (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and OPTOMER (registered trademark, manufactured by JSR Corporation).

[0083] Examples of a method for applying the oriented polymer composition to a substrate include known methods such as spin coating, extrusion, gravure coating, die coating, slit coating, bar coating, and applicator coating, and printing methods such as flexography. When the present optically absorptive anisotropic film is produced by a roll-to-roll continuous production method described below, the coating method typically employed is a printing method such as gravure coating, die coating, or flexography.

[0084] Methods for removing the solvent contained in the oriented polymer composition include natural drying, ventilation drying, heat drying, and reduced pressure drying.

[0085] In order to impart an alignment control force to the alignment film, rubbing is carried out as necessary (rubbing method). By selecting the rubbing direction, the direction of the alignment control force can be controlled arbitrarily.

[0086] A method for imparting an orientation control force by the rubbing method includes bringing an oriented polymer film formed on the surface of a substrate by applying an oriented polymer composition to the substrate and annealing the composition into contact with a rotating rubbing roll wrapped with a rubbing cloth.

[0087] <Photo-alignment film> A photo-alignment film is usually formed on the surface of a substrate by applying a composition containing a polymer or monomer having a photoreactive group and a solvent (hereinafter sometimes referred to as a "photo-alignment film-forming composition") to the substrate and irradiating the substrate with light (preferably polarized UV). Photo-alignment films are more preferable because the direction of the alignment control force can be freely controlled by selecting the polarization direction of the irradiated light.

[0088] The photoreactive group refers to a group that exhibits liquid crystal alignment ability upon irradiation with light. Specific examples include groups involved in photoreactions that induce molecular alignment upon irradiation with light or that are the origin of liquid crystal alignment ability, such as isomerization, dimerization, photocrosslinking, or photodecomposition. Among these, groups involved in dimerization or photocrosslinking are preferred because of their excellent alignment properties. As the photoreactive group, groups having an unsaturated bond, particularly a double bond, are preferred, and groups having at least one bond selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond) are particularly preferred.

[0089] Photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having an azoxybenzene structure. Photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

[0090] Among these, photoreactive groups involved in photodimerization reactions are preferred, and cinnamoyl and chalcone groups are preferred because they require a relatively small amount of polarized light irradiation for photoalignment and are likely to produce a photoalignment film with excellent thermal stability and stability over time. As a polymer having a photoreactive group, one having a cinnamoyl group such that the terminal of the polymer side chain has a cinnamic acid structure is particularly preferred.

[0091] The solvent contained in the composition for forming a photo-alignment film may be the same as the solvent contained in the above-mentioned alignment polymer composition, and may be appropriately selected depending on the solubility of the polymer or monomer having a photoreactive group.

[0092] The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted appropriately depending on the type of polymer or monomer and the desired thickness of the photo-alignment film, but is preferably at least 0.2% by mass, and more preferably in the range of 0.3 to 10% by mass. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide, or a photosensitizer, as long as the properties of the photo-alignment film are not significantly impaired.

[0093] The method for applying the composition for forming a photo-alignment film to a substrate may be the same as the method for applying the alignment polymer composition to a substrate. The method for removing the solvent from the applied composition for forming a photo-alignment film may be the same as the method for removing the solvent from the alignment polymer composition.

[0094] The polarized light irradiation can be performed by directly irradiating polarized UV light onto the substrate after removing the solvent from the composition for forming a photo-alignment film coated thereon, or by irradiating the substrate with polarized light and allowing the polarized light to pass through. It is particularly preferred that the polarized light be substantially parallel. The wavelength of the polarized light to be irradiated should be within a wavelength range in which the photoreactive group in the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) with a wavelength of 250 to 400 nm is particularly preferred. Examples of light sources used for polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. High-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are more preferred. These lamps are preferred because of their high emission intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV light can be irradiated by passing light from the light source through an appropriate polarizer. Examples of such polarizers include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire-grid polarizers.

[0095] If masking is performed during rubbing or polarized light irradiation, a plurality of regions (patterns) with different liquid crystal alignment directions can be formed.

[0096] The thickness of the alignment film is usually 10 nm to 10,000 nm, preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0097] <Method for manufacturing the present optical film and optically absorptive anisotropic film> This optically absorptive anisotropic film is obtained by orienting the absorption axis of the dichroic dye perpendicular to the film surface. In a host-guest optically absorptive anisotropic film such as this optically absorptive anisotropic film, the absorption axis of the dichroic dye is usually controlled by the orientation direction of the liquid crystal compound. By orienting the molecular long axis of the liquid crystal compound perpendicular to the film surface, the absorption axis of the dichroic dye can usually be aligned perpendicular to the film surface. The orientation direction of the liquid crystal compound is controlled by the properties of the substrate or alignment film onto which the composition containing the liquid crystal compound, dichroic dye, and solvent is applied, as well as the properties of the liquid crystal compound. That is, this optically absorptive anisotropic film can be obtained by using a substrate or alignment film that has an alignment control force that aligns perpendicular to the film surface (vertical direction), or by using a liquid crystal compound that tends to align vertically. Liquid crystal compounds with a smectic liquid crystal phase tend to align vertically. An optically absorptive anisotropic film obtained by orienting the absorption axis of a dichroic dye perpendicular to the film surface satisfies the above formula (1), but may not satisfy the above formulas (2) and (3). By using a compound that forms a high-order smectic liquid crystal phase as the liquid crystalline compound, an optically absorptive anisotropic film that also satisfies the above formulas (2) and (3) tends to be obtained. Specifically, the present optical film can be produced by carrying out the following steps (1) to (4) in the order described below. The optically absorptive anisotropic film can be obtained by transferring the optical film to another adherend via an adhesive or the like, and then removing the substrate. (1) A step of applying a composition containing a liquid crystal compound, a dichroic dye, and a solvent to a substrate to form a coating film. (2) A process of removing the solvent from the coating film to form a dry film. (3) A step of cooling the dried film to develop a liquid crystal phase. (4) A step of irradiating the liquid crystal compound with active energy rays to cure the liquid crystal compound. <Step (1)> Methods for applying a composition (optically absorptive anisotropic composition) containing a liquid crystalline compound, a dichroic dye, and a solvent to a substrate include the same methods as those exemplified as methods for applying an oriented polymer composition to a substrate.

[0098] <Step (2)> When the optically absorbing anisotropic composition contains a solvent, the solvent is usually removed from the coated optically absorbing anisotropic composition. Examples of methods for removing the solvent include natural drying, forced air drying, heat drying, and reduced-pressure drying. The dried film is preferably dried so that the residual solvent in the optically absorbing anisotropic film is 1% by weight or less relative to the total weight of the optically absorbing anisotropic film. The amount of residual solvent can be determined by peeling the optically absorbing anisotropic film from the substrate, weighing it, immersing the resulting optically absorbing anisotropic film in a solvent that dissolves the optically absorbing anisotropic film, such as tetrahydrofuran, and irradiating it with ultrasound for 10 minutes to extract the dissolved components, and then analyzing the solution by gas chromatography.

[0099] <Step (3)> The coated liquid crystal compound is usually heated to a temperature at which it transitions to a liquid crystal state or a solution state or higher, and then cooled to a temperature at which the liquid crystals are aligned, thereby forming a liquid crystal phase.

[0100] The temperature at which the applied liquid crystal compound aligns can be determined in advance by observing the texture of a composition containing the liquid crystal compound. Alternatively, the removal of the solvent and the alignment of the liquid crystals may be performed simultaneously. The temperature at this time varies depending on the type of solvent to be removed and the type of liquid crystal compound contained, but is preferably in the range of 50 to 200°C. When the substrate is a resin substrate, the temperature is more preferably in the range of 80 to 130°C.

[0101] <Step (4)> The aligned liquid crystal compound is irradiated with active energy rays to polymerize the liquid crystal compound.

[0102] The polymerized liquid crystal compound becomes a light absorption anisotropic film. A liquid crystal cured film containing a polymerizable liquid crystal compound polymerized while maintaining a smectic liquid crystal phase has higher polarization performance than conventional host-guest polarizing films, i.e., polarizing films obtained by polymerizing a polymerizable liquid crystal compound while maintaining a nematic liquid crystal phase, and is also superior in polarization performance and strength to films coated with only a dichroic dye or lyotropic liquid crystal.

[0103] The light source of the active energy ray may be any light source that generates ultraviolet rays, electron beams, X-rays, etc. Preferred are light sources having an emission distribution at wavelengths of 400 nm or less, such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps. It is more preferable that the active energy rays are ultraviolet rays parallel to the normal direction of the substrate.

[0104] The irradiation energy of the active energy rays is 10 to 5000 mJ / cm in the wavelength range effective for activating the polymerization initiator. 2 It is preferable to set it so that the intensity is within the range of 100 to 2000 mJ / cm. 2 The irradiation energy is 10 mJ / cm 2 If the temperature is too low, the liquid crystal compound tends to be insufficiently cured.

[0105] <Continuous manufacturing method of the present optical film> The present optical film is preferably continuously produced by a roll-to-roll method. An example of the main part of a method for continuously producing the optical film by a roll-to-roll method will be described with reference to FIG. 2. The following description will discuss a production method in which an alignment film is included between the substrate and the optically absorptive anisotropic film, but it goes without saying that the present optically absorptive anisotropic film does not necessarily have to include an alignment film. The following description will also discuss a production method in which a polymerizable liquid crystal compound is used as the liquid crystal compound, but the present invention is not limited to this.

[0106] First roll 210, in which the substrate is wound around first winding core 210A, is readily available on the market, for example. Examples of substrates available on the market in roll form include films made of cellulose ester, cyclic olefin resin, polycarbonate, polyethylene terephthalate, or polymethacrylate, among the substrates already exemplified above.

[0107] Next, the substrate is unwound from the first roll 210. The method of unwinding the substrate is performed by installing a suitable rotation means on the winding core 210A of the first roll 210 and rotating the first roll 210 by the rotation means. Alternatively, a suitable auxiliary roll 300 may be installed in the direction in which the substrate is transported from the first roll 210, and the substrate may be unwound by the rotation means of the auxiliary roll 300. Furthermore, by installing rotation means on both the first winding core 210A and the auxiliary roll 300, the transparent substrate may be unwound while applying an appropriate tension to the substrate.

[0108] When the substrate unwound from the first roll 210 passes through the coating device 211A, the composition for forming a photo-alignment film is coated onto the surface of the substrate by the coating device 211A. As the coating device 211A for continuously coating the composition for forming a photo-alignment film in this manner, gravure coating, die coating, and flexography are preferred.

[0109] The substrate that has passed through the coating device 211A is transported to the drying oven 212A, where it is dried, and a first coating film is continuously formed on the surface of the substrate. For example, a hot air drying oven that combines ventilation drying and heat drying is used as the drying oven 212A. The set temperature of the drying oven 212A is determined depending on the type of solvent contained in the composition for forming a photo-alignment film, etc. The drying oven 212A may be composed of multiple zones with different set temperatures, or may be a multiple drying oven with different set temperatures installed in series.

[0110] The obtained first coating film is irradiated with polarized light by the polarized UV irradiation device 213A, thereby obtaining a photo-alignment film.

[0111] Next, the substrate on which the photo-alignment film has been formed passes through coating device 211B. After coating the photo-alignment film with a composition containing a dichroic dye, a polymerizable liquid crystal compound, and a solvent by coating device 211B, the substrate passes through drying oven 212B to obtain a second coating film in which the polymerizable liquid crystal compound is aligned. Drying oven 212B not only removes the solvent from the composition containing the polymerizable liquid crystal compound and solvent coated on the photo-alignment film, but also provides thermal energy to align the polymerizable liquid crystal compound contained in the composition. Like drying oven 212A, drying oven 212B may be composed of multiple zones with different set temperatures, or may be composed of multiple drying ovens with different set temperatures installed in series.

[0112] The second coating film is transported to the active energy ray irradiation device 213B in a state in which the polymerizable liquid crystal compound contained in the second coating film is aligned. The active energy ray irradiation device 213B irradiates the second coating film with active energy rays. The polymerizable liquid crystal compound is polymerized in an aligned state by the irradiation of active energy rays by the active energy ray irradiation device 213B.

[0113] The optical film thus continuously produced is wound around the second winding core 220A to obtain the second roll 220. When winding, co-winding using an appropriate spacer may be performed.

[0114] In this way, the substrate passes from the first roll 210 through the coating device 211A, the drying oven 212A, the polarized UV irradiation device 213A, the coating device 211B, the drying oven 212B, and the active energy ray irradiation device 213B in this order, whereby the present optical film can be continuously produced in a roll-to-roll manner. When no alignment film is included between the substrate and the optically absorptive anisotropic film, the optical film can be produced by a similar production method that does not include the coating device 211A and the polarized UV irradiation device 213A.

[0115] <Three-dimensional optically absorptive anisotropic film> A three-dimensional optically absorptive anisotropic film can be formed by laminating the optically absorptive anisotropic film and a horizontal polarizing film. When laminating an optical film and a horizontal polarizing film, the optical film only needs to be laminated to the horizontal polarizing film on the optically absorptive anisotropic film side, and the substrate may be peeled off. The three-dimensional optically absorptive anisotropic film satisfies the following formula (6), where the absorption axis of the horizontal polarizing film is the x' axis, the transmission axis of the horizontal polarizing film is the y' axis, and the axis perpendicular to the x' and y' axes is the z' axis. In formula (6), Ax', Ay', and Az' all represent the absorbance at the absorption maximum wavelength of the dichroic dye in the optically absorptive anisotropic film. Ax' represents the absorbance of linearly polarized light vibrating in the x' direction, Ay' represents the absorbance of linearly polarized light oscillating in the y' direction, and Az' represents the absorbance of linearly polarized light oscillating in the z' direction. Ax' and Ay' are measured in the same manner as Ax and Ay. Az' can be calculated by the following formula (7): In the formula, Ay' (z=60) is the linearly polarized light oscillating in the y'-axis direction when the film is rotated 60° around the x'-axis. represents the absorbance of Ax'>Az'>Ay' (6) Ay' (z=60)=Ay' cos60°+Az' sin60° (7)

[0116] <Horizontal polarizing film> A horizontal polarizing film has a polarizing function with an absorption axis parallel to the film surface. Examples of horizontal polarizing films include stretched films onto which a dye having anisotropic absorption is adsorbed, and films coated with a dye having anisotropic absorption. Examples of dyes having anisotropic absorption include dichroic dyes.

[0117] A stretched film having adsorbed thereon a dye having absorption anisotropy is usually produced through the steps of uniaxially stretching a polyvinyl alcohol-based resin film, dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye, treating the polyvinyl alcohol-based resin film having adsorbed thereon with an aqueous boric acid solution, and washing the film with water after the treatment with the aqueous boric acid solution.

[0118] Polyvinyl alcohol resins are obtained by saponifying polyvinyl acetate resins. Examples of polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

[0119] The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The polymerization degree of the polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

[0120] Such a polyvinyl alcohol-based resin is formed into a film to obtain a raw film. The polyvinyl alcohol-based resin can be formed into a film by a known method. The thickness of the polyvinyl alcohol-based raw film is preferably 10 to 150 μm.

[0121] The uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out before, simultaneously with, or after dyeing with a dichroic dye. When uniaxial stretching is carried out after dyeing, this uniaxial stretching may be carried out before or during the boric acid treatment. It is also possible to carry out uniaxial stretching in these multiple stages. In uniaxial stretching, the film may be uniaxially stretched between rolls with different peripheral speeds, or may be uniaxially stretched using a heated roll. The uniaxial stretching may be dry stretching in which stretching is carried out in the air, or wet stretching in which the polyvinyl alcohol-based resin film is stretched in a swollen state using a solvent. The stretching ratio is usually 3 to 8 times.

[0122] Dyeing of a polyvinyl alcohol-based resin film with a dichroic dye is carried out by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. Examples of dichroic pigments include iodine and dichroic organic dyes, with iodine being preferred. Examples of dichroic organic dyes include dichroic direct dyes made of disazo compounds such as CI DIRECT RED 39, and dichroic direct dyes made of compounds such as trisazo and tetrakisazo. The polyvinyl alcohol resin film is preferably immersed in water before dyeing.

[0123] When the dichroic dye is iodine, a dyeing method is usually employed in which the polyvinyl alcohol resin film is immersed in an aqueous solution containing iodine and potassium iodide. The iodine content in the aqueous solution is usually 0.01 to 1 part by mass per 100 parts by mass of water. The potassium iodide content is usually 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually 20 to 40°C. The immersion time in this aqueous solution (dyeing time) is usually 20 to 1,800 seconds.

[0124] When the dichroic pigment is a dichroic organic dye, a method of dyeing a polyvinyl alcohol resin film by immersing it in an aqueous solution containing the water-soluble dichroic dye is usually used. The content of the dichroic organic dye in the aqueous solution is usually 1 × 10 per 100 parts by mass of water. -4 to 10 parts by mass, preferably 1×10 -3 to 1 part by mass, and more preferably 1×10 -3 ~1×10 -2 The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous solution is usually 20 to 80°C. The immersion time in the aqueous solution (dyeing time) is usually 10 to 1,800 seconds.

[0125] The boric acid treatment after dyeing with a dichroic dye can usually be carried out by immersing the dyed polyvinyl alcohol-based resin film in a boric acid aqueous solution. The content of boric acid in the boric acid aqueous solution is usually 2 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichroic dye, the boric acid aqueous solution preferably contains potassium iodide, and the content of potassium iodide is usually 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. The immersion time in the boric acid aqueous solution is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature for the boric acid treatment is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

[0126] The polyvinyl alcohol-based resin film after the boric acid treatment is usually washed with water. The washing can be carried out by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of the water used in the washing is usually 5 to 40°C. The immersion time is usually 1 to 120 seconds.

[0127] After washing with water, the film is dried to obtain a horizontal polarizing film. The drying can be performed using a hot air dryer or a far-infrared heater. The temperature for the drying is usually 30 to 100°C, preferably 50 to 80°C. The drying time is usually 60 to 600 seconds, preferably 120 to 600 seconds. The moisture content of the horizontal polarizing film is reduced to a practical level by the drying process. The moisture content is usually 5 to 20% by weight, preferably 8 to 15% by weight. If the moisture content is below 5% by weight, the horizontal polarizing film loses its flexibility, and may be damaged or broken after drying. If the moisture content exceeds 20% by weight, the thermal stability of the horizontal polarizing film may be impaired.

[0128] The thickness of the horizontal polarizing film obtained by uniaxially stretching the polyvinyl alcohol resin film, dyeing with a dichroic dye, treating with boric acid, washing with water and drying is preferably 5 to 40 μm.

[0129] Examples of films coated with a dye having absorption anisotropy include films obtained by coating a composition containing a dichroic dye having liquid crystal properties or a composition containing a dichroic dye and a polymerizable liquid crystal. It is preferable to use the same dichroic dye as that contained in the optically absorptive anisotropic film.

[0130] The film coated with the dye having absorption anisotropy is preferably thin, but if it is too thin, the strength decreases and the processability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 to 3 μm.

[0131] Specific examples of films coated with a dye having absorption anisotropy include films described in JP-A-2012-33249.

[0132] A polarizing plate can be obtained by laminating a transparent protective film on at least one surface of the horizontal polarizing film via an adhesive. The transparent protective film is preferably the same transparent film as the above-mentioned substrate.

[0133] In addition, the three-dimensional optically absorbing anisotropic film may be made of any suitable material used in the construction of liquid crystal displays, such as the present optically absorbing anisotropic film and horizontal polarizing film, as well as an antiglare layer, an antireflection layer, an antistatic layer, a light diffusion control layer, a brightness enhancement layer, a reflective layer, and a semi-transparent layer. [Example]

[0134] The present invention will be described in more detail below with reference to examples. In the examples, "%" and "parts" are by mass % and parts by mass unless otherwise specified.

[0135] Example 1 [Production of Optically Absorbent Anisotropic Composition] The following components were mixed and stirred at 80°C for 1 hour to obtain an optically absorptive anisotropic composition. The dichroic dye used was an azo dye described in the examples of JP-A-2013-101328. The polymerizable liquid crystal compounds represented by formulas (1-6) and (1-7) were synthesized according to the method described in Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996). Polymerizable liquid crystal compound: TIFF0007774654000015.tif17150 75 copies TIFF0007774654000016.tif17138 25 copies Dichroic dye 1: TIFF0007774654000017.tif1188 2.8 parts Polymerization initiator; 2-Dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals) 6 parts Leveling agents; Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) 0.3 parts Solvent: o-xylene 250 parts

[0136] [Measurement of phase transition temperature of polymerizable liquid crystal compounds] The phase transition temperature was confirmed by observing the texture using a polarizing microscope (BX-51, manufactured by Olympus Corporation) while heating the compound on a glass substrate with an alignment film. The polymerizable liquid crystal compound represented by formula (1-6) exhibited a crystalline phase to a smectic A phase at 95°C, a phase transition to a nematic phase at 111°C, and a phase transition to an isotropic liquid phase at 113°C during heating. It was confirmed that the compound exhibited a phase transition to a nematic phase at 112°C, a phase transition to a smectic A phase at 110°C, and a phase transition to a smectic B phase at 94°C during cooling. The polymerizable liquid crystal compound represented by formula (1-7) exhibited a crystalline phase to a smectic A phase at 81°C, a phase transition to a nematic phase at 121°C, and a phase transition to an isotropic liquid phase at 137°C during heating. During cooling, the phase transition to a nematic phase occurred at 133°C, to a smectic A phase at 118°C, and to a smectic B phase at 78°C. Similarly, the texture of the thermotropic nematic liquid crystal LC242 manufactured by BASF was observed, which showed a nematic phase but not a smectic phase.

[0137] [Production of optically absorbing anisotropic film] The optically absorptive anisotropic composition was applied to a 50 mm x 50 mm glass plate using a spin coater, and then dried for 1 minute in a drying oven set at 110°C to obtain a dried coating film in which the polymerizable liquid crystal compound and dichroic dye were oriented. After the dried coating film was naturally cooled to room temperature, it was irradiated with ultraviolet light (under a nitrogen atmosphere, wavelength: 365 nm, cumulative light intensity at 365 nm: 1000 mJ / cm) using a high-pressure mercury lamp (Uniquer VB-15201BY-A, manufactured by Ushio Inc.). 2 ) to polymerize the polymerizable liquid crystal compound, thereby obtaining an optically absorptive anisotropic film 1.

[0138] [Evaluation of optically absorbing anisotropic films] [Three-dimensional absorbance measurement] The absorbance of the optically absorptive anisotropic film 1 was measured as follows. Using an apparatus in which a folder with a prism polarizer was set on a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation), the three-dimensional absorbance at the wavelength showing maximum absorption was measured in the wavelength range of 380 to 680 nm with a 2-nm step by the double-beam method. Here, the three-dimensional absorbance means the absorbances (Ax, Ay, Az) in each direction with respect to linearly polarized light when an arbitrary direction in the film plane is taken as the x-axis, a direction perpendicular to the x-axis in the film plane is taken as the y-axis, and the film thickness direction of the film is taken as the z-axis. Specifically, the measurement was performed by rotating the sample with respect to the linearly polarized light that is the measurement light. Also, since the absorbance in the z direction is, by definition, light incidence from the side surface of the sample, it is difficult to measure. Therefore, the absorbance in the Az direction was estimated by tilting the x-y plane of the sample by 30° and 60° with respect to the vibration plane of the linearly polarized light that is the measurement light. Specifically, Ax(z = 30) and Ax(z = 60) were measured by making the same linearly polarized light incident as when Ax was measured in a state where the sample was rotated by 30° and 60° so as to include the y-axis, and similarly, Ay(z = 30) and Ay(z = 60) were measured by making the same linearly polarized light incident as when Ay was measured in a state where the sample was rotated by 30° and 60° so as to include the x-axis. In the case where there is no absorption anisotropy in the x-y plane, that is, when Ax and Ay are equal, since Ax(z = 30) = Ay(z = 30) and Ax(z = 60) = Ay(z = 60), Ax(z = 30) and Ay(z = 30) were designated as A(z = 30), and Ax(z = 60) and Ay(z = 60) were designated as A(z = 60). That is, when in the relationship of A(z = 30) < A(z = 60), the relationship of A(z = 30) < A(z = 60) < A(z = 90) = Az is satisfied. Further, if A(z = 30) > (Ax + Ay) / 2 or A(z = 60) > (Ax + Ay) / 2, then inevitably the following formula (1) is satisfied. Az > (Ax + Ay) / 2 (1) As a result of measuring the sample of Example 1 of this case, the three-dimensional absorbances at the wavelength of 526 nm, which is the wavelength of maximum absorption, were Ax = 0.029, Ay = 0.029, A(z = 30) = 0.146, and A(z = 60) = 0.502. That is, the optically absorptive anisotropic film 1 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 17.3 > 5 (2) Ay(z=60) / Ay = 17.3 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 1 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 1.7 μm.

[0139] Example 2 An optically absorptive anisotropic film 2 was prepared in the same manner as in Example 1, except that dichroic dye 2 was used instead of dichroic dye 1. Dichroic dye 2: TIFF0007774654000018.tif14150 2.8 parts

[0140] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 2 was measured. As a result, the three-dimensional absorbance at a wavelength of 606 nm, which is the maximum absorption wavelength, was Ax = 0.023, Ay = 0.023, A(z = 30) = 0.134, and A(z = 60) = 0.417. That is, the optically absorptive anisotropic film 2 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 18.1 > 5 (2) Ay(z=60) / Ay = 18.1 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 2 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 1.6 μm.

[0141] Example 3 An optically absorptive anisotropic film 3 was prepared in the same manner as in Example 1, except that dichroic dye 3 was used instead of dichroic dye 1. Dichroic dye 3: TIFF0007774654000019.tif13150 2.8 parts

[0142] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 3 was measured. As a result, the three-dimensional absorbance at the maximum absorption wavelength of 620 nm was Ax = 0.050, Ay = 0.050, A(z = 30) = 0.226, and A(z = 60) = 0.647. That is, the optically absorptive anisotropic film 3 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 12.9 > 5 (2) Ay(z=60) / Ay = 12.9 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 3 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and found to be 1.8 μm.

[0143] Example 4 An optically absorptive anisotropic film 4 was prepared in the same manner as in Example 1, except that dichroic dye 4 was used instead of dichroic dye 1. Dichroic dye 4: TIFF0007774654000020.tif12101 2.8 parts

[0144] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 4 was measured. As a result, the three-dimensional absorbance at the maximum absorption wavelength of 402 nm was Ax = 0.086, Ay = 0.086, A(z = 30) = 0.193, and A(z = 60) = 0.525. That is, the optically absorptive anisotropic film 4 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 6.1 > 5 (2) Ay(z=60) / Ay = 6.1 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 4 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 1.7 μm.

[0145] Example 5 An optically absorptive anisotropic film 5 was prepared in the same manner as in Example 1, except that dichroic dye 5 was used instead of dichroic dye 1. Dichroic dye 5: TIFF0007774654000021.tif13100 2.8 parts

[0146] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 5 was measured. As a result, the three-dimensional absorbance at the maximum absorption wavelength of 546 nm was Ax = 0.020, Ay = 0.020, A(z = 30) = 0.105, and A(z = 60) = 0.333. That is, the optically absorptive anisotropic film 5 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 16.7 > 5 (2) Ay(z=60) / Ay = 16.7 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 5 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 1.7 μm.

[0147] Example 6 [Production of composition for forming alignment film] Propylene glycol monomethyl ether was added to the alignment polymer to obtain a composition for forming an alignment film. The solid content of the alignment polymer is calculated from the concentration stated in the delivery specifications. Oriented polymer: Sunever (registered trademark) SE-610 (manufactured by Nissan Chemical Industries, Ltd.) 0.3 parts (1.0%) Propylene glycol monomethyl ether: 27.7 parts

[0148] [Production of optically absorbing anisotropic film] A polyethylene terephthalate film (Diafoil T140E25, manufactured by Mitsubishi Plastics, Inc.) was cut into a size of 80 x 80 mm, and its surface was subjected to a corona treatment (AGF-B10, manufactured by Kasuga Electric Co., Ltd.). An alignment film-forming composition was applied to the corona-treated film surface using a bar coater, and then dried for 1 minute in a drying oven set at 120°C to obtain an alignment film. The same liquid crystal cured film-forming composition as used in Example 1 was applied to the resulting alignment film using a bar coater, and then dried for 1 minute in a drying oven set at 110°C. The film was then irradiated with ultraviolet light (under a nitrogen atmosphere, wavelength: 365 nm, cumulative light intensity at 365 nm: 1000 mJ / cm) using a high-pressure mercury lamp (Uniqure VB-15201BY-A, manufactured by Ushio Inc.). 2 ) to polymerize the polymerizable liquid crystal compound, thereby obtaining an optically absorptive anisotropic film 6.

[0149] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 5 was measured. As a result, the three-dimensional absorbance at the maximum absorption wavelength of 526 nm was Ax=0.040, Ay=0.040, A(z=30)=0.184, and A(z=60)=0.602. That is, the optically absorptive anisotropic film 6 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 15.1 > 5 (2) Ay(z=60) / Ay = 15.1 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 6 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2.2 μm.

[0150] Example 7 An optically absorptive anisotropic film 7 was prepared in the same manner as in Example 6, except that dichroic dye 2 was used instead of dichroic dye 1.

[0151] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 7 was measured. As a result, the three-dimensional absorbance at a wavelength of 608 nm, which is the maximum absorption wavelength, was Ax = 0.032, Ay = 0.032, A(z = 30) = 0.184, and A(z = 60) = 0.588. That is, the optically absorptive anisotropic film 7 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 18.4 > 5 (2) Ay(z=60) / Ay = 18.4 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 7 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2.2 μm.

[0152] Example 8 An optically absorptive anisotropic film 8 was prepared in the same manner as in Example 6, except that dichroic dye 3 was used instead of dichroic dye 1.

[0153] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 8 was measured. As a result, the three-dimensional absorbance at the maximum absorption wavelength of 622 nm was Ax = 0.078, Ay = 0.078, A(z = 30) = 0.291, and A(z = 60) = 0.860. That is, the optically absorptive anisotropic film 8 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 11.0 > 5 (2) Ay(z=60) / Ay = 11.0 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 8 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2.3 μm.

[0154] Comparative Example 1 An optically absorptive anisotropic film 9 was prepared in the same manner as in Example 2, except that thermotropic nematic liquid crystal LC242 manufactured by BASF was used instead of the polymerizable liquid crystal compounds (1-6) and (1-7). This sample did not provide transparency, and molecular orientation of the polymerizable liquid crystal and dichroic dye was not achieved. TIFF0007774654000022.tif20133

[0155] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 9 was measured. As a result, the three-dimensional absorbance at a wavelength of 560 nm, which is the maximum absorption wavelength, was Ax = 0.327, Ay = 0.327, A(z = 30) = 0.317, and A(z = 60) = 0.312. That is, the optically absorptive anisotropic film 9 does not satisfy the following formulas (1), (2), and (3). Az< A(z=60)< A(z=30)< (Ax+Ay) / 2 Ax(z=60) / Ax = 1.0 Ay(z=60) / Ay = 1.0 [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 9 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 1.7 μm.

[0156] Comparative Example 2 An optically absorptive anisotropic film 10 was prepared in the same manner as in Example 6, except that thermotropic nematic liquid crystal LC242 (manufactured by BASF) was used instead of the polymerizable liquid crystal compounds (1-6) and (1-7). TIFF0007774654000023.tif20133

[0157] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 10 was measured. As a result, the three-dimensional absorbance at the maximum absorption wavelength of 488 nm was Ax = 0.072, Ay = 0.072, A(z = 30) = 0.133, and A(z = 60) = 0.275. That is, the optically absorptive anisotropic film 10 satisfies the formula (1) as follows, but does not satisfy the formulas (2) and (3). Az>A(z=60)> A(z=30)>(Ax+Ay) / 2 Ax(z=60) / Ax = 3.8 Ay(z=60) / Ay = 3.8 [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 10 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2.1 μm.

[0158] Comparative Example 3 An optically absorptive anisotropic film 11 was prepared in the same manner as in Example 7, except that the polymerizable liquid crystal compounds (1-6) and (1-7) were replaced with thermotropic nematic liquid crystal LC242 (manufactured by BASF). TIFF0007774654000024.tif20133

[0159] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 11 was measured. As a result, the three-dimensional absorbance at a wavelength of 560 nm, which is the maximum absorption wavelength, was Ax = 0.071, Ay = 0.071, A(z = 30) = 0.125, and A(z = 60) = 0.275. That is, the optically absorptive anisotropic film 10 satisfies the formula (1) as follows, but does not satisfy the formulas (2) and (3). Az>A(z=60)> A(z=30)>(Ax+Ay) / 2 Ax(z=60) / Ax = 3.9 Ay(z=60) / Ay = 3.9 [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 11 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2.1 μm.

[0160] Comparative Example 4 An optically absorptive anisotropic film 12 was prepared in the same manner as in Example 8, except that thermotropic nematic liquid crystal LC242 (manufactured by BASF) was used instead of the polymerizable liquid crystal compounds (1-6) and (1-7). TIFF0007774654000025.tif20133

[0161] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 12 was measured. As a result, the three-dimensional absorbance at the maximum absorption wavelength of 594 nm was Ax = 0.133, Ay = 0.133, A(z = 30) = 0.220, and A(z = 60) = 0.460. That is, the optically absorptive anisotropic film 12 satisfies the formula (1) as follows, but does not satisfy the formulas (2) and (3). Az>A(z=60)> A(z=30)>(Ax+Ay) / 2 Ax(z=60) / Ax = 3.5 Ay(z=60) / Ay = 3.5 [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 12 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2.1 μm.

[0162] Example 9 An optically absorptive anisotropic film 13 was prepared in the same manner as in Example 6, except that dichroic dye 1, dichroic dye 3, and dichroic dye 4 were used simultaneously instead of dichroic dye 1.

[0163] [Three-dimensional absorbance measurement] As in Example 1, the three-dimensional absorbance of the optically absorptive anisotropic film 13 was measured, and as a result, maximum absorptions resulting from the three types of dyes were obtained. First absorption: The three-dimensional absorbance at a wavelength of 400 nm was Ax = 0.115, Ay = 0.115, A(z = 30) = 0.274, and A(z = 60) = 0.692. That is, the optically absorptive anisotropic film 13 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 6.0 > 5 (2) Ay(z=60) / Ay = 6.0 > 5 (3) Second absorption: The three-dimensional absorbance at a wavelength of 526 nm was Ax = 0.062, Ay = 0.062, A(z = 30) = 0.220, and A(z = 60) = 0.639. That is, the optically absorptive anisotropic film 13 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 10.2 > 5 (2) Ay(z=60) / Ay = 10.2 > 5 (3) Third absorption: The three-dimensional absorbance at a wavelength of 622 nm was Ax = 0.049, Ay = 0.049, A(z = 30) = 0.187, and A(z = 60) = 0.468. That is, the optically absorptive anisotropic film 13 satisfies the following formulas (1), (2), and (3). Az> A(z=60)> A(z=30)> (Ax+Ay) / 2 (1) Ax(z=60) / Ax = 11.3 > 5 (2) Ay(z=60) / Ay = 11.3 > 5 (3) [Film thickness measurement] The thickness of the liquid crystal cured film in the optically absorptive anisotropic film 13 was measured using a laser microscope (LEXT, manufactured by Olympus Corporation) and was found to be 2.3 μm.

[0164] Example 10 [Polarizing plate manufacturing] A 75 μm-thick polyvinyl alcohol film with an average degree of polymerization of approximately 2,400 and a saponification degree of 99.9 mol% or greater was immersed in pure water at 30°C, followed by an aqueous solution of iodine / potassium iodide / water in a weight ratio of 0.02 / 2 / 100 at 30°C for iodine dyeing (iodine dyeing step). The polyvinyl alcohol film after the iodine dyeing step was then immersed in an aqueous solution of potassium iodide / boric acid / water in a weight ratio of 12 / 5 / 100 at 56.5°C for boric acid treatment (boric acid treatment step). The polyvinyl alcohol film after the boric acid treatment step was washed with pure water at 8°C and then dried at 65°C to obtain a horizontal polarizing film (27 μm thick after stretching) in which iodine was adsorbed and aligned in the polyvinyl alcohol. Stretching was performed during the iodine dyeing step and the boric acid treatment step. The total stretch ratio during this stretching was 5.3x. The resulting horizontal polarizing film and a saponified triacetyl cellulose film (KC4UYTAC, 40 μm, manufactured by Konica Minolta) were bonded together using a nip roll with a water-based adhesive. The resulting laminate was dried at 60°C for 2 minutes while maintaining a tension of 430 N / m, yielding a polarizing plate (1) with a triacetyl cellulose film as a protective film on one side. The water-based adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (Kuraray Poval KL318, manufactured by Kuraray) and 1.5 parts of water-soluble polyamide epoxy resin (Sumirez Resin 650, manufactured by Sumika Chemtex, 30% solids aqueous solution) to 100 parts of water. The liquid crystal cured film side of the optically absorptive anisotropic film 13 obtained in Example 9 was then bonded to this polarizing plate using a pressure-sensitive adhesive to produce a three-dimensional optically absorptive anisotropic film as shown in Figure 3.

[0165] [Three-dimensional absorbance measurement] The three-dimensional absorbance of the obtained composite polarizing plate was measured in the same manner as in Example 1. The three-dimensional absorbance here refers to the absorbance in each direction (Ax', Ay', Az') when the absorption axis of the polarizing plate is in the direction of x', the transmission axis direction of the polarizing plate is in the direction of y', and the film thickness direction of the liquid crystal cured film is in the direction of z'. The magnitude relationship between Ax', Ay', and Az' was determined by measuring Ax' and Ax' (z=60) and Ay' and Ay' (z=60). Second absorption: The three-dimensional absorbance at a wavelength of 526 nm was Ax' = 3.158, Ay' = 0.065, and Ay' (z = 60) = 0.614. Since the relationship is Ay' (z=60) = Ay' cos60° + Az' sin60°, it is calculated that Az' is approximately 0.671. Therefore, it was confirmed that formula (6) is satisfied. Ax'> Az'> Ay' (6)

[0166] As shown in Figure 4, a polarizing plate was attached to the rear side of the LCD panel via a pressure-sensitive adhesive, and then a three-dimensional optically absorptive anisotropic film was attached to the front side of the LCD panel via a pressure-sensitive adhesive so that the polarizing plate side faced the panel.The appearance was evaluated, and it was confirmed that while clear visibility was maintained from the front, visibility from the side was reduced, providing an anti-peeping function. [Industrial Applicability]

[0167] The optically absorptive anisotropic film of the present invention is thin and can be produced by a simple manufacturing method, and is useful as a material for imparting a more effective anti-peeping function to displays of mobile phones, bank ATMs, and the like. [Explanation of symbols]

[0168] 210 Roll 1 210A core 220 Roll 2 220A winding core 211A, 211B Coating equipment 212A,212B Drying oven 213A Polarized UV irradiation device 213B Active energy ray irradiation equipment 300 Auxiliary Roll 1. Optically absorptive anisotropic film 2. Adhesive layer 3 Horizontal polarizing film 4. Three-dimensional optically absorbing anisotropic film 5 LCD panel

Claims

1. A light-absorbing anisotropic film is a cured film of a composition containing a dichroic dye and a liquid crystalline compound, and when any direction in the film plane is defined as the x-axis, a direction in the film plane perpendicular to the x-axis is defined as the y-axis, and a film thickness direction perpendicular to the x-axis and y-axis is defined as the z-axis, the light absorbance of the film satisfies the following formulas (1), (2), and (3), the film thickness is 5 μm or less, and the film shows a Bragg peak in X-ray diffraction measurement. Az>(Ax+Ay) / 2 (1) Ax (z=60) / Ax>11.0 (2) Ay (z=60) / Ay>11.0 (3) (Ax, Ay, Az, Ax(z=60), and Ay(z=60) are all absorbances at the absorption maximum wavelength of the dichroic dye in the optically absorptive anisotropic film, Ax represents the absorbance of linearly polarized light vibrating in the x-axis direction, Ay represents the absorbance of linearly polarized light vibrating in the y-axis direction, Az represents the absorbance of linearly polarized light vibrating in the z-axis direction, Ax (z=60) represents the absorbance of linearly polarized light oscillating in the x-axis direction when the film is rotated 60° around the y-axis, Ay (z=60) represents the absorbance of linearly polarized light oscillating in the y-axis direction when the film is rotated 60° around the x-axis.

2. 2. The optically absorptive anisotropic film according to claim 1, which contains a leveling agent containing a polyacrylate compound as a main component or a leveling agent containing a fluorine atom-containing compound as a main component.

3. 3. The optically absorptive anisotropic film according to claim 1, wherein the content of the leveling agent is 0.1 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the liquid crystal compound.

4. 4. The optically absorptive anisotropic film according to claim 1, wherein the liquid crystalline compound forms a smectic liquid crystal phase.

5. 5. The optically absorptive anisotropic film according to claim 1, wherein the liquid crystalline compound forms a high-order smectic liquid crystal phase.

6. 6. The optically absorptive anisotropic film according to claim 1, wherein the dichroic dye in the optically absorptive anisotropic film has a maximum absorption wavelength in the range of 500 nm to 600 nm.

7. 7. The optically absorptive anisotropic film according to claim 1, which contains at least three kinds of dichroic dyes having different maximum absorption wavelengths.

8. An optical film comprising the optically absorptive anisotropic film according to any one of claims 1 to 7 and a substrate.

9. 9. The optical film according to claim 8, which does not include an alignment film between the substrate and the optically absorptive anisotropic film.

10. The method for producing an optical film according to claim 8 or 9, wherein the following steps (1) to (4) are carried out in this order: (1) A step of applying a composition containing a liquid crystal compound, a dichroic dye, and a solvent to a substrate to form a coating film. (2) A step of removing the solvent from the coating film to form a dry film. (3) A step of cooling the dried film to develop a liquid crystal phase. (4) A step of curing the liquid crystal compound by irradiating it with active energy rays.

11. The method according to claim 10, wherein a long film is used as the substrate and the optical film is continuously produced.

12. A three-dimensional optically absorptive anisotropic film obtained by laminating the optically absorptive anisotropic film according to any one of claims 1 to 7 and a horizontal polarizing film, wherein the three-dimensional optically absorptive anisotropic film satisfies the following formula (6), where the absorption axis of the horizontal polarizing film is the x'-axis, the transmission axis of the horizontal polarizing film is the y'-axis, and the axis perpendicular to the x'-axis and y'-axis is the z'-axis: Ax'>Az'>Ay' (6) (Ax', Ay', and Az' are all absorbances at the absorption maximum wavelength of the dichroic dye in the optically absorptive anisotropic film, Ax' represents the absorbance of linearly polarized light vibrating in the x' direction, Ay′ represents the absorbance of linearly polarized light vibrating in the y′ direction, Az' represents the absorbance of linearly polarized light vibrating in the z' direction.)

13. 13. The three-dimensional optically absorptive anisotropic film according to claim 12, wherein the horizontal polarizing film comprises polyvinyl alcohol and a dichroic dye.

14. 13. The three-dimensional optically absorptive anisotropic film according to claim 12, wherein the horizontal polarizing film contains a dichroic dye and a liquid crystalline compound, or contains a dichroic dye having liquid crystal properties.

15. 15. The three-dimensional optically absorptive anisotropic film according to claim 12, wherein the optically absorptive anisotropic film is laminated on the horizontal polarizing film via a pressure-sensitive adhesive or adhesive.

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