Coating solution for alignment films, laminate, and method for manufacturing optical laminates

Abstract

To provide a coating liquid for alignment films that can suitably produce an alignment solidified layer of a liquid crystal compound that can suppress light leakage, a laminate containing an alignment film obtained from the coating liquid for alignment films, and a method for manufacturing an optical laminate. [Solution] The coating liquid for alignment films according to an embodiment of the present invention is a coating liquid for alignment films comprising a film-forming component and an alkali metal and / or alkaline earth metal, wherein the alkali metal and / or alkaline earth metal is present in an amount of 700 ppm or more relative to the total weight of the alignment film formed.

Description

Technical Field

[0001] The present invention relates to a coating liquid for an alignment film, a laminate, and a method for manufacturing an optical laminate.

Background Art

[0002] An alignment and curing layer of a liquid crystal compound is used for a retardation layer. The alignment and curing layer of the liquid crystal compound is produced, for example, by forming an alignment film on a substrate and applying a solution of the liquid crystal compound to the alignment film. However, the alignment and curing layer of the liquid crystal compound obtained by the above method may have poor alignment of the liquid crystal compound, and as a result, light leakage may occur.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to solve the above problems, and its main object is to provide a coating liquid for an alignment film that can suitably produce an alignment and curing layer of a liquid crystal compound capable of suppressing light leakage, a laminate including the alignment film obtained from the coating liquid for an alignment film, and a method for manufacturing an optical laminate.

Means for Solving the Problems

[0005] [1] The coating liquid for an alignment film according to an embodiment of the present invention includes a film-forming component and an alkali metal and / or an alkaline earth metal, and contains 700 ppm or more of the alkali metal and / or the alkaline earth metal with respect to the total weight of the formed alignment film. [2] One embodiment is the coating liquid for an alignment film according to the above item [1], which contains magnesium as the alkaline earth metal. [3] A laminate according to an embodiment of the present invention comprises a substrate and an orientation film, wherein the orientation film contains 700 ppm or more of alkali metals and / or alkaline earth metals relative to the total weight of the orientation film. [4] One embodiment is the laminate described in item [3] above, comprising magnesium as an alkaline earth metal. [5] One embodiment is the laminate according to item [3] or [4], further comprising an orientation solidification layer of a liquid crystal compound on the side opposite to the substrate with respect to the orientation film. [6] A method for manufacturing an optical laminate according to an embodiment of the present invention includes the steps of forming a polarizer and transferring the orientation solidification layer of the liquid crystal compound from the laminate described in item [5] above to the polarizer. [Effects of the Invention]

[0006] According to embodiments of the present invention, a coating liquid for an alignment film capable of producing an alignment film that can suppress light leakage in the resulting alignment solidified layer of a liquid crystal compound, and a laminate comprising the alignment film can be realized. Furthermore, according to embodiments of the present invention, a laminate comprising an alignment solidified layer of a liquid crystal compound capable of suppressing light leakage can be realized, and a method for manufacturing an optical laminate comprising an alignment solidified layer of a liquid crystal compound capable of suppressing light leakage can be realized. [Modes for carrying out the invention]

[0007] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

[0008] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows: (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference measured with light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference measured with light of wavelength 550nm at 23°C. Re(λ) can be calculated using the formula: Re(λ) = (nx - ny) × d, where d (nm) is the thickness of the layer (film). (3)Angle In this specification, when an angle is mentioned, unless otherwise specified, that angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°.

[0009] A. Overview of coating liquids for alignment films The coating liquid for alignment films according to embodiments of the present invention contains a film-forming component and an alkali metal and / or alkaline earth metal, and contains 700 ppm or more of the alkali metal and / or alkaline earth metal relative to the total weight of the alignment film formed. With such a configuration, the water content of the coating liquid for alignment films can be reduced. As a result, defects in the resulting alignment film can be reduced and poor alignment restricting force of the alignment film can be suppressed, and as a result, light leakage of the alignment solidification layer of the liquid crystal compound obtained from the alignment film can be suppressed. The inventors of the present invention have found that light leakage in the alignment solidification layer of liquid crystal compounds is due to poor alignment of the alignment solidification layer of liquid crystal compounds, and that poor alignment is due to poor alignment restricting force of the alignment film. As a result of diligent investigation into this problem, the inventors of the present invention have found that if alkali metals and / or alkaline earth metals are included in a specific proportion in the coating liquid for the alignment film, the water content of the coating liquid for the alignment film is reduced, and the poor alignment restricting force of the alignment film is suppressed, thus completing the present invention.

[0010] In one embodiment, the alignment coating solution contains magnesium as an alkaline earth metal. By containing 700 ppm or more of magnesium in the alignment coating solution, the water content of the alignment coating solution can be particularly reduced, and as a result, light leakage in the alignment solidified layer of the liquid crystal compound can be further suppressed.

[0011] B. Details of the coating liquid for alignment films The coating solution for oriented films according to embodiments of the present invention comprises a film-forming component, an alkali metal and / or alkaline earth metal, and a solvent for dissolving or dispersing them. In the present invention, the coating solution for oriented films is a concept that includes a dispersion medium, and therefore, "solution" may encompass "dispersion".

[0012] The film-forming component can be any suitable material, as long as the coating film formed by the component has the properties of an oriented film. To give the coating film the properties of an oriented film, any appropriate orientation treatment can be employed. Specifically, this includes rubbing treatment and photo-orientation treatment. The processing conditions for each orientation treatment can be any appropriate conditions depending on the purpose. Examples of film-forming components that can be subjected to rubbing treatment include polyimide resins and polyvinyl alcohol resins. Examples of film-forming components that can be subjected to photo-alignment treatment include photoreactive components. Examples of photoreactive components include photoisomerized compounds, photopolymerized compounds, photodimerized compounds, and photodegradable compounds. Preferably, the photoreactive component is a photodimerized compound. Examples of photodimerized compounds include cinnamate derivatives (e.g., polyvinyl cinnamate), coumarin derivatives, and chalcone derivatives. Preferably, the photodimerized compound is a cinnamate derivative, and more preferably polyvinyl cinnamate. Such photoreactive components can improve the orientation of the liquid crystal compound in the orientation-solidified layer of the liquid crystal compound. The photoreactive components may be used individually or in combination of two or more types. Preferably, the orientation treatment is a photo-alignment treatment. The embodiments of the present invention will be described below in the case where the film-forming component is a photoreactive component that can undergo photo-orientation treatment.

[0013] Examples of alkali metals include lithium, sodium, and potassium. Alkali metals may be used individually or in combination of two or more. Examples of the alkaline earth metal include beryllium, magnesium, and calcium. The alkaline earth metal is preferably magnesium. The alkaline earth metal may be used alone or in combination of two or more kinds. The alkali metal and the alkaline earth metal may be used in combination. As the alkali metal and / or the alkaline earth metal, preferably the alkaline earth metal, more preferably magnesium. If the alkali metal and / or the alkaline earth metal is magnesium, the water content rate of the coating liquid for the alignment film can be particularly reduced.

[0014] Any suitable solvent can be used. Examples of solvents include halogenated hydrocarbons, phenols, aromatic hydrocarbons, ketones, esters, alcohols, amides, nitriles, ethers, pyridine, carbon disulfide, ethyl cellsolve, and butyl cellsolve. Examples of halogenated hydrocarbons include chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene. Examples of phenols include phenol and parachlorophenol. Examples of aromatic hydrocarbons include benzene, toluene, xylene, methoxybenzene, and 1,2-dimethoxybenzene. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, and N-methyl-2-pyrrolidone. Examples of esters include ethyl acetate and butyl acetate. Examples of alcohols include t-butyl alcohol, 1-methoxy-2-propanol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, and 2-methyl-2,4-pentanediol. Examples of amides include dimethylformamide and dimethylacetamide. Examples of nitriles include acetonitrile and butyronitrile. Examples of ethers include diethyl ether, dibutyl ether, and tetrahydrofuran. The solvent is preferably an alcohol, and more preferably 1-methoxy-2-propanol. Such a solvent ensures high solubility of the film-forming component in the solvent and allows the solvent to volatilize at a low temperature, thereby suppressing variations in the thickness of the oriented film during film formation. The solvent may be used alone or in combination of two or more types.

[0015] The coating liquid for the alignment film may contain any suitable additive. Examples of the additive include antioxidants such as hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, lactone antioxidants, amine antioxidants, hydroxylamine antioxidants, vitamin E antioxidants, and other antioxidants; hindered amine light stabilizers; ultraviolet absorbers such as benzotriazole, benzophenone, triazine, and benzoate; surfactants; polyelectrolytes; conductive complexes; pigments; dyes; antistatic agents; antiblocking agents; and lubricants. The type, number, combination, addition amount, etc. of the additives can be appropriately set according to the purpose.

[0016] The coating liquid for the alignment film contains the film-forming component, for example, in an amount of 1% to 10% by weight, preferably 2% to 8% by weight. If the film-forming component in the coating liquid for the alignment film is within such a range, a desired viscosity can be obtained and the coating property can be improved.

[0017] The coating liquid for the alignment film contains an alkali metal and / or an alkaline earth metal, for example, in an amount of 700 ppm or more, preferably 700 ppm to 2000 ppm, more preferably 750 ppm to 1500 ppm, and still more preferably 800 ppm to 1200 ppm, based on the total weight of the obtained alignment film. When the alkali metal and / or the alkaline earth metal is magnesium, the coating liquid for the alignment film contains, for example, 700 ppm or more, preferably 700 ppm to 1500 ppm, more preferably 750 ppm to 1200 ppm, and still more preferably 800 ppm to 1000 ppm, based on the total weight of the obtained alignment film. If the alkali metal and / or the alkaline earth metal in the coating liquid for the alignment film is within such a range, the moisture content of the coating liquid for the alignment film can be suppressed, and as a result, the light leakage of the alignment curing layer of the liquid crystal compound can be suppressed. The content ratio of the alkali metal and the alkaline earth metal in the coating liquid for the alignment film is measured by ICP-MS, for example, by subjecting the coating liquid for the alignment film to pressurized acid decomposition. The content ratio of the alkali metal and the alkaline earth metal in the alignment film is a value obtained by converting the value obtained by ICP-MS with the coating liquid for the alignment film into a content ratio with respect to the solid content obtained by removing the solvent from the coating liquid for the alignment film. In addition, alkali metals and / or alkaline earth metals in the orientation film coating solution may typically exist in the form of alkali metal ions (cations) and / or alkaline earth metal ions (cations).

[0018] The solid content concentration of the coating liquid for alignment films is, for example, 1% to 10% by weight, preferably 2% to 8% by weight, and more preferably 2% to 7% by weight. If the solid content concentration of the coating liquid for alignment films is within this range, the desired viscosity can be obtained and the coating properties can be improved.

[0019] The moisture content of the coating liquid for the alignment film is, for example, less than 5.0% by weight, preferably 4.0% by weight or less, more preferably 3.0% by weight or less, and even more preferably 1.0% by weight or less. The lower limit of the moisture content of the coating liquid for the alignment film is, for example, 0.0% by weight or more, and also, for example, 0.1% by weight. If the moisture content of the coating liquid for the alignment film is within this range, defects in the alignment restricting force of the resulting alignment film can be suppressed. The moisture content is measured, for example, by introducing the gas obtained by heating the coating liquid for the alignment film into a coulometric titration type moisture meter.

[0020] The viscosity of the coating liquid for the orientation film is, for example, 1 Pa·s to 20 Pa·s, preferably 1 Pa·s to 10 Pa·s, and more preferably 1 Pa·s to 2.5 Pa·s. If the coating liquid for the orientation film has such a viscosity, the coating properties can be improved. The viscosity of the coating liquid for the orientation film is measured using a viscometer at a temperature of 23°C and an angular velocity of 5.24 rad / s, in accordance with the viscosity measurement method using a cone-plate type rotational viscometer specified in JIS Z 8803:2011.

[0021] C. Method for manufacturing a coating solution for orientation films The coating liquid for alignment films according to embodiments of the present invention is prepared by dissolving a film-forming component in a solvent to obtain an alignment film solution, and then contacting the alignment film solution with an alkali metal salt and / or an alkaline earth metal salt.

[0022] Any suitable method can be used to dissolve the film-forming component in a solvent. For example, one method for dissolving the film-forming component in a solvent is to add the film-forming component to the solvent, stir for a predetermined time, and then allow it to stand to degas. The stirring time is, for example, 1 minute to 3 hours, preferably 3 minutes to 1 hour. The degassing time (standing time) is, for example, 10 minutes to 5 hours, preferably 30 minutes to 3 hours. This allows us to obtain an orientation film solution in which the film-forming component is dissolved in a solvent.

[0023] Examples of alkali metal salts include the alkali metal sulfates, alkali metal carbonates, and alkali metal chlorides mentioned above. Alkali metal salts may be used individually or in combination of two or more types. Examples of alkaline earth metal salts include the above-mentioned alkaline earth metal sulfates, alkaline earth metal carbonates, and alkaline earth metal chlorides. Preferably, the alkaline earth metal salt is the above-mentioned alkaline earth metal sulfate, and more preferably, magnesium sulfate. If the alkaline earth metal salt is magnesium sulfate, the moisture content of the coating solution for the alignment film can be reduced. The alkaline earth metal salts may be used individually or in combination of two or more types. Alkali metal salts and alkaline earth metal salts may be used in combination. Preferably, the alkali metal salt and / or alkaline earth metal salt is an alkaline earth metal salt, and more preferably, magnesium sulfate. If the alkaline earth metal salt is magnesium sulfate, the moisture content of the coating solution for the alignment film can be reduced in particular.

[0024] Instead of alkali metal salts and / or alkaline earth metal salts, for example, silicates containing alkali metal ions (monovalent cations) and / or alkaline earth metal ions (divalent cations) can be used. Examples of silicates containing alkali metal ions and / or alkaline earth metal ions include molecular sieves (types 3A and 4A). If the silicate containing alkali metal ions and / or alkaline earth metal ions is a molecular sieve (types 3A and 4A), the moisture content of the coating solution for the alignment film can be reduced in particular.

[0025] Any suitable method can be used to bring the alignment film solution into contact with an alkali metal salt and / or an alkaline earth metal salt. Examples of contact methods include passing the alignment film solution through a syringe filled with an alkali metal salt and / or an alkaline earth metal salt, adding the alkali metal salt and / or an alkaline earth metal salt to the alignment film solution, or dropping the alignment film solution onto the alkali metal salt and / or an alkaline earth metal salt. The contact time is, for example, 12 to 48 hours, preferably 18 to 36 hours. The contact temperature is, for example, 0°C to 50°C, preferably 20°C to 40°C.

[0026] Subsequently, if necessary, the alignment membrane solution and the alkali metal salts and / or alkaline earth metal salts are separated. Any suitable method can be used for separation. Examples of separation methods include filtration and decantation. Filtration is preferred as the separation method. For example, a membrane filter can be used for filtration.

[0027] As a result, a coating liquid for orientation films can be obtained.

[0028] D. Laminate A laminate according to an embodiment of the present invention comprises a substrate and an orientation film on one side of the substrate.

[0029] Any suitable material can be used as the substrate. Examples of substrate materials include metal foil, polyethylene terephthalate (PET), triacetylcellulose (TAC), norbornene-based resin, polyvinyl alcohol, polyimide, polyarylate, polycarbonate, polysulfone, polyethersulfone, glass, and quartz. Any appropriate thickness can be used for the substrate. For example, the substrate thickness is 1 μm to 200 μm, preferably 2 μm to 150 μm.

[0030] The alignment film is an alignment film formed from the alignment film coating liquid described in sections B and C above. The alignment film has an alignment restricting force. The alignment restricting force can be imparted by photo-aligning the photoreactive component of the alignment film coating liquid. Furthermore, the alignment film contains alkali metals and / or alkaline earth metals. The alkali metal and / or alkaline earth metal is an alkali metal and / or alkaline earth metal derived from the coating solution for the alignment film, and may exist in the alignment film in the form of a salt of the alkali metal and / or alkaline earth metal, or may coordinate to the film-forming component in the form of an ionic alkali metal and / or alkaline earth metal.

[0031] The thickness of the alignment film is, for example, 0.01 μm to 5 μm, preferably 0.05 μm to 3 μm. If the thickness of the alignment film is within this range, the dissolution of the alignment film by the solvent of the liquid crystal coating solution can be suppressed, and as a result, thickness unevenness of the alignment film can be suppressed.

[0032] The alignment film contains alkali metals and / or alkaline earth metals in an amount of, for example, 700 ppm or more, preferably 700 ppm to 2000 ppm, more preferably 750 ppm to 1500 ppm, and even more preferably 800 ppm to 1200 ppm, relative to the total weight of the alignment film. If the alkali metal and / or alkaline earth metal is magnesium, the alignment film contains, for example, 700 ppm or more, preferably 700 ppm to 1500 ppm, more preferably 750 ppm to 1200 ppm, and even more preferably 800 ppm to 1000 ppm, relative to the total weight of the alignment film. If the alkali metal and / or alkaline earth metal in the alignment film is within such a range, the defects in the alignment restricting force of the alignment film can be reduced.

[0033] The thickness of the laminate is, for example, 3 μm to 200 μm, preferably 5 μm to 150 μm.

[0034] E. Manufacturing method of laminates A laminate according to an embodiment of the present invention is manufactured by applying the above-mentioned orientation film coating liquid to a substrate and drying it to obtain a coating film, and then applying a photo-orientation treatment to the coating film to impart an orientation restricting force to the coating film and obtain an orientation film.

[0035] Any suitable method can be used for applying the alignment coating solution to the substrate (coating method). Examples of coating methods include using a bar coater, spin coater, roll coater, or gravure coater. The coating method can be appropriately set according to the composition and type of the alignment coating solution used, the desired properties of the alignment film, etc. Any suitable drying method can be employed. The drying temperature is, for example, 80°C to 150°C, preferably 90°C to 120°C. The drying time is, for example, 30 seconds to 5 minutes, preferably 1 minute to 3 minutes. In this way, a coating liquid for orientation films is applied to the substrate and dried, thereby forming a coating film on the substrate.

[0036] The coating film can have any appropriate thickness depending on the desired thickness of the orientation film. The thickness of the coating film is, for example, 0.01 μm to 5 μm, preferably 0.05 μm to 3 μm.

[0037] Any suitable method can be employed for the photo-alignment treatment. For example, one method of photo-alignment treatment is to irradiate the film-forming component (photoreactive component) with active energy rays. As the active energy ray, any appropriate active energy ray can be used depending on the photoreactive component used. Examples of active energy rays include infrared rays, visible light, and ultraviolet rays. Preferably, the active energy ray is ultraviolet light. When the photoreactive component is a photodimerized compound, the active energy ray is preferably polarized ultraviolet light (polarized UV).

[0038] Any suitable light source can be used as the light source for the active energy rays. When polarized ultraviolet light is used as the active energy ray, examples of ultraviolet light sources include high-pressure mercury lamps, metal halide lamps, and LED lamps. Any suitable method can be used to polarize ultraviolet light to produce polarized ultraviolet light. Examples of methods for producing polarized ultraviolet light include using prisms, polarizing films, quartz glass, etc. Any appropriate irradiation dose of active energy rays can be used. For example, 5 J / cm² 2 ~50J / cm 2 Preferably 10 J / cm² 2 ~40J / cm 2 The amount of ultraviolet radiation is the total amount of UVC (250nm~260nm), UVB (280nm~320nm), UVA (320nm~390nm), and UVV (395nm~445nm) measured with an ultraviolet light intensity meter (UV POWER PUCK, manufactured by EIT). In the case of multiple irradiations, the total amount of radiation is used.

[0039] Any suitable method can be used for irradiating with active energy rays. In particular, when irradiating a photodimerizable compound with polarized ultraviolet light, polarized ultraviolet light in a polarization direction (irradiation direction) perpendicular to the desired orientation direction is irradiated onto the photodimerizable compound coating so that the alignment film can obtain an orientation restricting force in the desired orientation direction. As a result, only adjacent combinations of reactive groups of the photodimerizable compound in a direction along the polarization direction of the polarized ultraviolet light react to form a dimer, and an alignment film having an orientation restricting force in a specific orientation direction can be obtained. Consequently, the alignment solidified layer of the liquid crystal compound obtained on the alignment film can have a specific orientation direction.

[0040] With this type of photo-alignment treatment method, the alignment film can be given an orientation restricting force in a desired direction relative to the longitudinal direction of the elongated substrate, and as a result, the formed alignment film can exhibit an orientation restricting force in a predetermined direction. In other words, an alignment film having an orientation restricting force in any appropriate direction relative to the longitudinal direction can be formed on an elongated substrate. As a result, an orientation film having orientation-regulating force in a desired direction can be obtained.

[0041] F. Laminate comprising an orientation-solidified layer of liquid crystal compounds The laminate according to an embodiment of the present invention may further include an orientation-solidified layer of a liquid crystal compound (hereinafter sometimes referred to as a liquid crystal orientation-solidified layer) on the side opposite to the substrate with respect to the orientation film.

[0042] Typically, the liquid crystal alignment solidification layer consists of rod-shaped liquid crystal compounds that are homogeneously oriented according to the orientation restricting force of the alignment film described in sections D and E above. The liquid crystal alignment solidification layer can be produced by coating an alignment film with a liquid crystal coating solution containing rod-shaped liquid crystal compounds, then heating the solution to orient the liquid crystal compounds and fix their orientation. In this specification, "orientation-solidified layer" refers to a layer in which liquid crystal compounds are oriented in a predetermined direction within the layer due to the orientation-regulating force of the orientation film described above, and this orientation state is fixed. Furthermore, the term "orientation-solidified layer" encompasses the concept of an orientation-cured layer obtained by curing liquid crystal monomers. Specific examples of liquid crystal compounds and details of methods for forming liquid crystal alignment solidification layers are described, for example, in Japanese Patent Publication No. 2006-163343 and Japanese Patent Publication No. 2006-178389. The descriptions in these publications are incorporated herein by reference.

[0043] The optical properties and thickness of the liquid crystal alignment solidification layer can be arbitrarily and appropriately set according to the purpose.

[0044] G. Method for manufacturing optical laminates The above-mentioned laminate can be suitably used in a method for manufacturing an optical laminate. The method for manufacturing an optical laminate includes the steps of forming a polarizer and transferring the orientation solidification layer of the liquid crystal compound provided in the laminate described in item F above to one side of the polarizer.

[0045] Any suitable polarizer can be used as the polarizer. For example, the resin film forming the polarizer may be a single-layer resin film or may be obtained using a laminate of two or more layers. In one embodiment, the polarizer is preferably obtained using a laminate of two or more layers. Specific examples of polarizers obtained using laminates of two or more layers, and details of methods for manufacturing polarizers, are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0046] Any suitable method can be used to transfer the liquid crystal alignment solidification layer of the laminate to one side of the polarizer. For example, one method for transferring the liquid crystal alignment solidification layer to one side of the polarizer is to attach the side of the laminate with the liquid crystal alignment solidification layer to one side of the polarizer via an adhesive layer, and then peel off the substrate from the laminate attached to the polarizer. In this case, when peeling off the substrate from the laminate, the alignment film may be peeled off together with the substrate, or only the substrate may be peeled off and the alignment film may be transferred together with the liquid crystal alignment solidification layer to one side of the polarizer. The liquid crystal alignment solidification layer transferred in this manner can be used as a phase difference layer in an optical laminate.

[0047] In this way, an optical laminate can be obtained comprising a polarizer and a phase difference layer on one side of the polarizer. The optical laminate obtained by the above method can suppress light leakage from the phase difference layer. In such an optical laminate, the optical properties of the phase difference layer can be arbitrarily and appropriately set according to its purpose. [Examples]

[0048] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement and evaluation methods for each characteristic are as follows.

[0049] (1) Measurement of solid content concentration After measuring the weight of only the container holding the alignment film solution (orientation film coating liquid), an arbitrary amount of the alignment film solution (orientation film coating liquid) was placed in the container, its weight was measured, and the weight of the alignment film solution (orientation film coating liquid) was calculated as the difference between the weight of the container alone and the weight of the solution. Subsequently, the container was placed in an oven (model name "SPH102", manufactured by ESPEC) and dried at 110°C for 1 hour. After drying, the weight of the container was measured, and the difference between the weight of the solution and the weight of the solution alone was taken as the weight of the alignment film components (total weight of film-forming components and alkali metals and / or alkaline earth metals), and the solid content concentration of the alignment film solution (orientation film coating liquid) was calculated using the following formula. Formula: Solid content concentration (weight %) = (Weight of orientation film components (g)) / (Weight of orientation film solution (coating liquid for orientation film) (g)) × 100

[0050] (2) Measurement of viscosity Viscosity was measured using a viscometer (model "TV-200EL", manufactured by Toki Sangyo Co., Ltd.) in accordance with the method for measuring viscosity using a cone-plate type rotational viscometer as specified in JIS Z 8803:2011, at a temperature of 23°C and an angular velocity of 5.24 rad / s.

[0051] (3) Measurement of the content of alkali metals or alkaline earth metals 180 mg of the alignment film coating solution obtained in the examples and comparative examples was weighed into a Teflon® container, acid was added, and the container was sealed. Microwave irradiation was then performed using UltraWAVE (Milestone General Corporation, frequency: 2.45 GHz, maximum pressure: 150 bar, maximum temperature: 250 °C, total irradiation time: 40 minutes) to perform pressurized acid decomposition. Subsequently, ultrapure water was added to a final volume of 20 mL, and the solution was diluted up to 25 times. The content ratio of each alkali metal and alkaline earth metal element was measured using ICP-MS (model name "8800", Agilent Technologies), and the values ​​were calculated assuming that all volatile components (solvent) had evaporated from the alignment film coating solution.

[0052] (4) Measurement of moisture content 0.03 g of the alignment film coating solution obtained in the examples and comparative examples was weighed, placed in a heating vaporizer (model name "VA-300," manufactured by Nitto Seiko Airanatech Co., Ltd.), heated to 150°C, and the resulting gas was introduced into the titration cell of a coulometric titration type moisture meter (model name "CA-310," manufactured by Nitto Seiko Airanatech Co., Ltd., anode solution: Aquamicron AKX (manufactured by Mitsubishi Chemical Corporation), cathode solution: Aquamicron CXU (manufactured by Mitsubishi Chemical Corporation)) to measure the moisture content and verify the moisture percentage.

[0053] (5) Measurement of thickness The laminates with liquid crystal alignment solidification layers obtained in the examples and comparative examples were each cut in the thickness direction, and the cross-sections were photographed using a SEM (model name "Regulus8230", magnification: 50,000x, manufactured by Hitachi High-Tech Corporation). From the captured images, the thickness of the alignment film and the thickness of the liquid crystal alignment solidification layer were calculated.

[0054] (6) Measurement of phase difference The phase difference values ​​(Re(λ)) of the liquid crystal alignment solidified layers obtained in the examples and comparative examples were automatically measured using an Axometrics "AxoScan" device. The measurement wavelengths were 450 nm, 550 nm, and 650 nm, and the measurement temperature was 23°C.

[0055] (7) Evaluation of light penetration Two polarizing plates were placed in a cross-polarized state. Then, the liquid crystal alignment solidification layers obtained in the examples and comparative examples were inserted between the two polarizing plates so that the absorption axis of one polarizing plate and the slow axis of the liquid crystal alignment solidification layer were parallel. Light was then incident from one side of the two polarizing plates using a halogen light source (model name "JCR12V100WB", manufactured by Olympus). Images from the other side of the other polarizing plate were captured using a microscope with a camera (microscope: model name "BX51", magnification: 200x, manufactured by Olympus; camera: model name "DP22", manufactured by Olympus). The number of bright spots occurring in the captured images was counted, and the light penetration of the liquid crystal alignment solidification layer was evaluated according to the following evaluation criteria. Note that at the points where bright spots occurred, alignment defects occurred in the liquid crystal alignment solidification layer, indicating defects in the alignment restricting force of the alignment film. "〇": No bright spots were observed. "△": 1 to 9 bright spots were observed. "×": More than 10 bright spots were observed.

[0056] <Example 1> [Preparation of coating solution A for alignment film] 0.10 g of polyvinyl cinnamate (poly(vinyl cinnamate), number average molecular weight: 40,000, powder, manufactured by Sigma-Aldrich), a film-forming component, was dissolved in 1-methoxy-2-propanol to a solid content concentration of 6.2% by weight. The mixture was stirred for 5 minutes and allowed to stand for 1 hour to prepare an orientation film solution. Next, 10 mL of the orientation film solution was added dropwise to 1 g of magnesium sulfate in a sample tube at 23°C, and the sample tube was allowed to stand for 24 hours. Subsequently, the solution was filtered through a membrane filter (product name "Disposable Membrane Filter Unit DISMIC 25HP", pore size: 0.2 μm, manufactured by ADVANTEC) to obtain the filtrate, which was the orientation film coating solution A. The solid content concentration of orientation film coating solution A was 6.3% by weight, the water content of orientation film coating solution A was 3.4% by weight, and the viscosity of orientation film coating solution A was 2.40 Pa·s. The content of alkali metals and / or alkaline earth metals relative to the total weight of the components forming the orientation film A in the orientation film coating solution A was 1125 ppm, and the content of magnesium relative to the total weight of the components forming the orientation film A in the orientation film coating solution A was 860 ppm. [Fabrication of Laminate A] The above-mentioned orientation coating solution A was applied to a 10 cm square polyethylene terephthalate (PET) substrate (100 μm thick) using a spin coater, and dried at 100°C for 1 minute to obtain a coating film with a thickness of 0.05 μm. Next, polarized UV light was applied to the coating film at 20 J / cm². 2 An alignment film A was formed by irradiation. The PET substrate was photo-oriented using polarized ultraviolet light so that the alignment film A was oriented at a 45° angle to the direction of one side of the substrate. This resulted in a laminate A having the alignment film A. The thickness of the alignment film A was 0.05 μm, the content of alkali metals and / or alkaline earth metals relative to the total weight of the alignment film A was 1125 ppm, and the content of magnesium relative to the total weight of the alignment film A was 860 ppm. [Formation of liquid crystal alignment solidification layer A] A liquid crystal compound solution was prepared by dissolving 10 parts by weight of a polymerizable liquid crystal monomer exhibiting a nematic liquid crystal phase (BASF, trade name "Paliocolor LC242") and 3 parts by weight of a photopolymerization initiator for the polymerizable liquid crystal monomer (BASF, trade name "Irgacure 907") in 40 parts by weight of cyclopentanone, stirring for 5 minutes, and allowing it to stand for 1 hour. The liquid crystal compound solution was applied to the side of the alignment film A on a PET substrate that was opposite to the substrate (the side with alignment restricting force), and then dried at 80°C for 4 minutes to align the liquid crystal compound and obtain an alignment layer A of the liquid crystal compound. This alignment layer A of the liquid crystal compound was irradiated with ultraviolet light at a dose of 400 mJ / cm². 2 A 10 cm square laminate A was obtained by curing the alignment layer A of the liquid crystal compound by irradiation, thereby forming a liquid crystal alignment solidification layer A on the alignment film A. The refractive index characteristics of this liquid crystal alignment solidification layer A showed the relationship nx>ny=nz, and the angle between the slow axis of the liquid crystal alignment solidification layer A and the irradiation direction (polarization direction) of polarized ultraviolet light was 90°. The thickness of the liquid crystal alignment solidification layer A was 2 μm, the in-plane phase difference value Re(550) of the liquid crystal alignment solidification layer A was 220 nm, Re(450) / Re(550) was 1.08, and Re(650) / Re(550) was 0.96. The evaluation of the light penetration of the liquid crystal alignment solidification layer A was "○".

[0057] <Example 2> Alignment film coating solution B was obtained in the same manner as in Example 1, except that the alignment film solution was added to 5 g of molecular sieves (Type: 3A, trade name "Molecular Sieves 3A 1 / 8", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) instead of magnesium sulfate. Alignment film B was prepared using the obtained alignment film coating solution B to obtain a liquid crystal alignment solidification layer B (laminated body B). The solid content of the alignment film coating solution B was 6.4% by weight, the water content of the alignment film coating solution B was 0.39% by weight, and the viscosity of the alignment film coating solution B was 2.04 Pa·s. The content of alkali metals and / or alkaline earth metals relative to the total weight of the components forming the alignment film B in the alignment film coating solution B was 1213 ppm, and the content of magnesium relative to the total weight of the components forming the alignment film B in the alignment film coating solution B was 793 ppm. The thickness of orientation film B was 0.05 μm, the content of alkali metals and / or alkaline earth metals relative to the total weight of orientation film B was 1213 ppm, and the content of magnesium relative to the total weight of orientation film B was 793 ppm. The refractive index characteristics of liquid crystal alignment solidification layer B showed the relationship nx>ny=nz, and the angle between the slow axis of liquid crystal alignment solidification layer B and the irradiation direction (polarization direction) of polarized ultraviolet light was 90°. The thickness of liquid crystal alignment solidification layer B was 2 μm, the in-plane phase difference value Re(550) of liquid crystal alignment solidification layer B was 220 nm, Re(450) / Re(550) was 1.08, and Re(650) / Re(550) was 0.96. The evaluation of light penetration of liquid crystal alignment solidification layer B was "○".

[0058] <Comparative Example 1> An alignment film coating solution C was obtained in the same manner as in Example 1, except that the alignment film solution was used directly as the coating solution for the alignment film instead of being added dropwise to magnesium sulfate. An alignment film C was prepared using the obtained alignment film coating solution C to obtain a liquid crystal alignment solidification layer C (laminated body C). The solid content concentration of the alignment film coating solution C was 6.2% by weight, the water content of the alignment film coating solution C was 5.0% by weight, and the viscosity of the alignment film coating solution C was 2.65 Pa·s. Since alkali metals and / or alkaline earth metals could not be detected in the alignment film coating solution C, the content ratio of alkali metals and / or alkaline earth metals relative to the total weight of the components forming the alignment film C, and the content ratio of magnesium relative to the total weight of the components forming the alignment film C, could not be calculated. The thickness of the alignment film C was 0.05 μm. Furthermore, the percentage of alkali metals and / or alkaline earth metals relative to the total weight of the alignment film C, as well as the percentage of magnesium relative to the total weight of the alignment film C, could not be calculated. The refractive index characteristics of the liquid crystal alignment solidification layer C showed the relationship nx>ny=nz, and the angle between the slow axis of the liquid crystal alignment solidification layer C and the irradiation direction (polarization direction) of polarized ultraviolet light was 90°. The thickness of the liquid crystal alignment solidification layer C was 2 μm, the in-plane phase difference value Re(550) of the liquid crystal alignment solidification layer C was 220 nm, Re(450) / Re(550) was 1.08, and Re(650) / Re(550) was 0.96. The evaluation of light penetration of the liquid crystal alignment solidification layer C was "×".

[0059] [evaluation] Comparing Examples 1 and 2 with Comparative Example 1, the liquid crystal alignment solidified layer prepared using the alignment coating solution of Comparative Example 1 showed a "×" evaluation for light leakage, whereas the liquid crystal alignment solidified layers prepared using the alignment coating solutions of Examples 1 and 2, in which the content ratio of alkali metals and / or alkaline earth metals relative to the total weight of the alignment film was 700 ppm or more, showed a "〇" evaluation for light leakage, indicating that light leakage in the liquid crystal alignment solidified layer was suppressed. [Industrial applicability]

[0060] The coating liquid for alignment films according to embodiments of the present invention can be suitably used in the manufacture of liquid crystal alignment solidification layers. The laminate according to embodiments of the present invention can be suitably used in the manufacture of optical laminates, and the optical laminate obtained by the manufacturing method of optical laminates according to embodiments of the present invention can be suitably applied to image display devices (typically liquid crystal display devices and organic EL display devices).

Claims

1. A coating liquid for alignment films, It comprises a film-forming component and an alkali metal and / or alkaline earth metal, A coating liquid for orientation films, comprising 700 ppm or more of the alkali metal and / or alkaline earth metal relative to the total weight of the orientation film formed.

2. The coating liquid for orientation films according to claim 1, wherein the alkaline earth metal includes magnesium.

3. It comprises a substrate and an orientation film, A laminate in which the orientation film contains 700 ppm or more of alkali metals and / or alkaline earth metals relative to the total weight of the orientation film.

4. The laminate according to claim 3, wherein the alkaline earth metal includes magnesium.

5. The laminate according to claim 3 or 4, further comprising an orientation solidification layer of a liquid crystal compound on the side opposite to the substrate with respect to the orientation film.

6. The process of forming a polarizer, The polarizer comprises the step of transferring the orientation solidified layer of the liquid crystal compound from the laminate described in claim 5, A method for manufacturing an optical laminate, including [the specified element].