JP2015191142A - Phase difference film, optical film, and method of producing optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase difference film which can improve adhesion between a phase difference layer (liquid crystal layer) and a polarizer of the phase difference film not through a protection film, a primer layer or the like.SOLUTION: A phase difference film 1 according to the present invention comprises a base material 11, an alignment layer 12, and a phase difference layer 13 comprising a polymerizable liquid crystal compound, laminated in this order. The phase difference layer 13 comprises a polymerizable liquid crystal composition comprising two kinds of photopolymerization initiators (first photopolymerization initiator and second photopolymerization initiator) having mutually different absorption peak wavelengths.

Description

  The present invention relates to a retardation film, an optical film obtained by attaching a polarizer to the retardation film, and a method for producing the optical film.

  In recent years, flat panel displays capable of three-dimensional display have been provided. In the three-dimensional image display, it is necessary to selectively provide a right-eye video and a left-eye video to the viewer's right eye and left eye, respectively, using, for example, a passive method.

  In the passive method, pixels that are continuous in the vertical direction of the image display panel are sequentially assigned to the right eye and the left eye, and driven by the image data for the right eye and the left eye, respectively. Display images simultaneously. In addition, a retardation film is disposed on the panel surface of the image display panel, and light emitted by linearly polarized light from the right-eye and left-eye pixels is converted into circularly polarized light having different directions for the right-eye and left-eye. Accordingly, in the passive method, glasses equipped with corresponding polarizing filters are attached, and a right eye image and a left eye image are selectively provided to the viewer's right eye and left eye, respectively.

  In the retardation film, an alignment film and a retardation layer (liquid crystal layer) are sequentially provided on a substrate made of a transparent film material. In the retardation film, the retardation layer is formed of a liquid crystal material, and the alignment of the liquid crystal material is patterned by the alignment regulating force of the alignment film. By this patterning, in the retardation film, the right eye region and the left eye region are alternately formed with a certain width in order corresponding to the pixel assignment in the liquid crystal display panel, and the right eye pixel and the left eye pixel are sequentially formed. A phase difference corresponding to each of the light emitted from the light is given.

  Thus, in the image display device, the image display panel is driven by the sequentially input image data, the pixels of the odd lines and the even lines are driven by the image data for the right eye and the left eye, respectively, and for the right eye and the left eye. Display images simultaneously. Also, the output light from the image display panel is converted to linearly polarized light by the polarizing filter placed on the image display panel, and the right and left eyes are handled by the retardation film placed on the polarizing filter. To give the phase difference.

  By the way, in an image display device such as a liquid crystal display device, various optical films for the purpose of hard coating, antireflection, electromagnetic wave shielding and the like are provided on the panel surface of the image display panel. In these optical films, various functional layers corresponding to the intended function are provided on the surface of the substrate made of a transparent film, and an adhesive layer (adhesive layer) is provided for the purpose of bonding to the upper and lower layers. It is done. Here, the adhesive layer is produced, for example, by applying an adhesive to the entire surface of the substrate, and is provided for attaching the optical film to a desired object. Thereby, the optical film mentioned above is affixed and hold | maintained on a panel surface with an adhesive bond layer in the manufacture process of an image display apparatus.

  In such an optical film, for example, in Patent Document 1, from the viewpoint of reducing the thickness of the optical film, a polarizer and a retardation layer (liquid crystal layer) are bonded to the panel surface without using a film. Technology has been proposed.

  However, when the liquid crystal layer and the polarizer are bonded directly via the adhesive layer, the adhesion at the interface between the liquid crystal layer and the adhesive layer is not sufficient, and when used under high temperature and high humidity, Separation may occur with the polarizer. The reason why the adhesiveness is lowered is considered to be greatly affected by the polarizer contracted by moisture absorption because it is laminated with the polarizer without using the protective film. Further, when a polarizing element containing defects is peeled from the glass substrate of the liquid crystal cell, peeling is likely to occur at the interface between the liquid crystal layer and the polarizer, and reworkability tends to be poor. For this reason, in the technology of Patent Document 1 described above, it is proposed to improve the adhesion by applying a further layer (referred to as “primer layer”). By forming such a layer, For example, there is a tendency that it is difficult to control the dimension of an important pattern when performing three-dimensional display.

JP 2012-220554 A

  The present invention has been proposed in view of the above situation, and improves the adhesion between the retardation layer (liquid crystal layer) of the retardation film and the polarizer without using a protective film or a primer layer. It aims at providing the retardation film which can be manufactured, the optical film obtained by sticking a polarizer to the retardation film, and the manufacturing method of the optical film.

  This inventor repeated earnest examination in order to solve the above-mentioned subject. As a result, by adding two types of photopolymerization initiators that react at different wavelengths to the retardation layer, and controlling the reaction time such as cleavage of the photopolymerization initiator with a light source that outputs different wavelengths, The inventors have found that the adhesion with the polarizer layer can be enhanced, and completed the present invention. That is, the present invention provides the following.

  (1) In the present invention, a base material, an alignment layer, and a retardation layer containing a polymerizable liquid crystal compound are laminated in this order, and the retardation layer has two types of absorption peak wavelengths different from each other. A retardation film comprising a polymerizable liquid crystal composition containing a photopolymerization initiator.

  (2) The present invention is a retardation film in which a base material, an alignment layer, and a retardation layer containing a polymerizable liquid crystal compound are laminated in this order, and an adhesive layer is interposed on the surface of the retardation layer. A polarizer is laminated, and the retardation layer is composed of a polymerizable liquid crystal composition containing two types of photopolymerization initiators having absorption peak wavelengths different from each other. is there.

  (3) In the present invention, an adhesive layer is provided on the surface of the retardation layer with respect to a retardation film in which a base material, an alignment layer, and a retardation layer containing a polymerizable liquid crystal compound are laminated in this order. A method for producing an optical film obtained by laminating a polarizer via, comprising the polymerizable liquid crystal compound and two types of photopolymerization initiators having different absorption peak wavelengths on the alignment layer A liquid crystal composition coating step for coating the polymerizable liquid crystal composition to be used, and a first light source that irradiates ultraviolet rays for reacting only the first photopolymerization initiator of the photopolymerization initiator, A retardation layer forming step of forming a retardation layer by curing a coating film of a polymerizable liquid crystal composition, and an adhesive on the surface of the retardation layer of the retardation film obtained by forming the retardation layer The composition is applied, and a polarizer is laminated on the coating film of the adhesive composition A polarizer laminating step, and an absorption peak wavelength of a second photopolymerization initiator of the photopolymerization initiator as an emission wavelength, and an ultraviolet ray having an emission wavelength for curing the adhesive composition. And an adhesive layer forming step of forming an adhesive layer by curing the coating film of the adhesive composition using the light source of No. 2.

  (4) In the invention according to (3), in the retardation layer forming step, the present invention includes an absorption peak wavelength of the first photopolymerization initiator as the first light source, and the second light. An optical film manufacturing method using a light source having an emission wavelength excluding an absorption peak wavelength of a polymerization initiator.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesiveness of the phase difference layer (liquid crystal layer) of a phase difference film and a polarizer can be improved, without passing through a protective film, a primer layer, etc.

It is sectional drawing of a phase difference film. It is sectional drawing which shows the optical film which affixed the polarizer on retardation film. It is a figure which shows the absorption curve of the alpha-hydroxy ketone type compound. It is a figure which shows the absorption curve of the alpha-amino ketone type compound. It is a figure which shows the absorption curve of a titanocene type compound. It is a figure which shows the emission spectrum of an electrodeless UV lamp. It is a figure which shows the emission spectrum of a low pressure mercury lamp. It is a flowchart which shows the flow of the manufacturing method (retardation film production process S1) of retardation film. It is a flowchart which shows the flow of the manufacturing method of the optical film which affixed the polarizer on the phase difference film.

Hereinafter, a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings in the following order. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention.
1. 1. Configuration of retardation film 2. Retardation layer (liquid crystal layer) Method for producing retardation film, method for producing optical film

<< 1. Composition of retardation film >>
FIG. 1 is a cross-sectional view of a retardation film 1 according to the present embodiment. As shown in FIG. 1, a retardation film 1 has an alignment layer 12 formed on a substrate 11, and a retardation layer (liquid crystal layer) containing a polymerizable liquid crystal composition for forming a retardation layer on the alignment layer 12. ) 13 is formed.

  In such a retardation film 1, the retardation layer 13 formed on the base material 11 is bonded or transferred to a polarizer via an adhesive layer such as a UV adhesive, and is applied to the retardation film 1. An optical film on which a polarizer is bonded is formed. Specifically, FIG. 2 is a cross-sectional view showing an example of the optical film 2. As shown in FIG. 2, the optical film 2 is formed by bonding a polarizer 21 to a retardation film 1 via an adhesive layer 20 such as a UV adhesive.

  Here, in the optical film 2, when the polarizer 21 is bonded to the retardation layer 13, the polarizer 21 is laminated without using a protective film or a primer layer made of an acrylic resin or the like. Thereby, the whole thickness of the optical film 2 can be made thin, and it can fully respond to the request | requirement of thickness reduction in recent years. However, in general, when a polarizer is laminated without a protective film, for example, in a high-temperature and high-humidity environment, the polarizer contracts due to moisture absorption and adhesion decreases, and the retardation layer and the polarizer May cause peeling.

  In this regard, in the retardation film 1 according to the present embodiment, the polymerizable liquid crystal composition constituting the retardation layer 13 contains two types of photopolymerization initiators having different absorption peak wavelengths. Yes. Thus, in the phase difference layer 13, it is possible to control the reaction timing such as cleavage of the photopolymerization initiator by a light source that outputs different wavelengths by containing the photopolymerization initiator that reacts at different wavelengths. Become. Thereby, in the retardation film 1 which concerns on this Embodiment, the adhesiveness of the phase difference layer 13 and the polarizer 21 can be improved effectively, and peeling between the phase difference layer 13 and the polarizer 21 is possible. Is suppressed, and a sufficiently thin optical film can be manufactured.

  The polarizer 21 is not particularly limited and a known one can be used. For example, uniaxially stretched by adsorbing a dichroic material such as iodine or a dichroic dye on a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film, dehydrated polyvinyl alcohol or polyvinyl chloride. Examples include polyene-based oriented films such as treated with hydrochloric acid.

<Base material>
The base material 11 is a transparent film material, has a function of supporting the alignment layer 12, and is formed in a long shape. The substrate 11 preferably has a small phase difference, and the in-plane retardation (in-plane retardation value, hereinafter also referred to as “Re value”) is preferably in the range of 0 nm to 10 nm, and preferably in the range of 0 nm to 5 nm. More preferably, it is in the range, and further preferably in the range of 0 nm to 3 nm. If the Re value exceeds 10 nm, for example, the display quality of a flat panel display using a pattern alignment film may deteriorate, which is not preferable.

The Re value is an index indicating the degree of birefringence in the in-plane direction of the refractive index anisotropic body. The refractive index in the slow axis direction having the largest refractive index in the in-plane direction is Nx, and the slow axis direction is in the slow axis direction. When the refractive index in the orthogonal fast axis direction is Ny, and the thickness in the direction perpendicular to the in-plane direction of the refractive index anisotropic body is d,
Re [nm] = (Nx−Ny) × d [nm]
It is a value represented by. The Re value can be measured by, for example, a parallel Nicol rotation method using a phase difference measuring device KOBRA-WR (manufactured by Oji Scientific Instruments).

  The transmittance of the substrate 11 in the visible light region is preferably 80% or more, and more preferably 90% or more. The transmittance of the transparent film substrate can be measured, for example, according to JIS K7361-1 (Plastic—Testing method for total light transmittance of transparent material).

  The substrate 11 is preferably a flexible material having flexibility that can be wound into a roll. Examples of such flexible materials include acrylic polymers (acrylic resins), cellulose derivatives, norbornene polymers, cycloolefin polymers, polymethyl methacrylate, polyvinyl alcohol, polyimide, polyarylate, polyethylene terephthalate, polysulfone, polyethersulfone, and amorphous. Examples include polyolefins, modified acrylic polymers, polystyrene, epoxy resins, polycarbonates, polyesters, and the like.

  The thickness of the base material 11 is not particularly limited as long as it is within a range in which the necessary self-supporting property can be imparted to the retardation film, depending on the use of the retardation film produced using the alignment film. Usually, it is preferably within the range of 25 μm to 125 μm, more preferably within the range of 25 μm to 80 μm, and even more preferably within the range of 25 μm to 60 μm. When the thickness of the base material 11 is less than 25 μm, the necessary self-supporting property may not be imparted to the retardation film. On the other hand, when the thickness exceeds 125 μm, when the retardation film is long, processing waste increases when the long retardation film is cut into a single-phase retardation film. Or wear of the cutting blade may be accelerated.

  The base material 11 is not restricted to the structure which consists of a single layer, You may have the structure by which the several layer was laminated | stacked. When it has the structure by which the several layer was laminated | stacked, the layer of the same composition may be laminated | stacked, and the several layer which has a different composition may be laminated | stacked.

<Alignment layer>
The alignment layer 12 is composed of an alignment film that is a cured product obtained by applying (coating) a composition for alignment layer (alignment film composition) on the substrate 11 and curing the composition. The alignment film constituting the alignment layer 12 is not particularly limited. For example, the alignment layer 12 can be formed by a photo-alignment method in which a photo-alignment material that exhibits photo-alignment properties by irradiation with polarized light is used for alignment by light irradiation.

  Note that the alignment film constituting the alignment layer 12 may be a pattern alignment film formed in a pattern or a solid film formed in a solid shape on the substrate 11. In the case of a pattern alignment film, the alignment pattern may be formed by, for example, a rubbing process in which the uneven shape is rolled with a roll having an uneven shape, and the photo-alignment property is obtained by irradiation with polarized light as described above. You may form by the photo-alignment system made to align by light irradiation using the photo-alignment material to exhibit. When forming a pattern alignment film by rubbing, the alignment layer (pattern alignment layer) 12 may be any material that contains a widely used energy ray curable resin (such as an ultraviolet curable resin). Also good.

[Composition for alignment layer (alignment film composition)]
For example, when the alignment layer 12 is formed by a photo-alignment method, the alignment layer 12 contains an alignment film composition described below. This alignment film composition contains a photo-alignment material that exhibits photo-alignment properties when irradiated with polarized light, and a solvent that dissolves the photo-alignment material.

(Photo-alignment material)
The photo-alignment material refers to a material that can exhibit an alignment regulating force by irradiation with polarized ultraviolet rays. The alignment regulating force means that an alignment layer containing a photo-alignment material is formed, and a liquid crystal compound (polymerizable liquid crystal composition for forming a retardation layer) is formed on the alignment layer. The function to arrange in the direction.

  The photo-alignment material is not particularly limited as long as it exerts alignment regulating force by irradiating polarized light. Such photo-alignment materials include a photoisomerization material that reversibly changes the alignment regulation force by changing only the molecular shape by cis-trans change, and a photoreactive material that changes the molecule itself by irradiating polarized light. Can be broadly classified. In the present embodiment, any of a photoisomerization material and a photoreactive material can be suitably used, but it is more preferable to use a photoreactive material. Since the photoreactive material is a material that reacts with polarized light to react with molecules and develops alignment regulating power, it becomes possible to irreversibly develop alignment regulating power, and the stability over time of the alignment regulating power Excellent.

  The photoreactive material can be further classified according to the type of reaction caused by polarized light irradiation. Specifically, a photodimerization type material that develops alignment regulation force by the photodimerization reaction, a photodecomposable material that develops alignment regulation force by the photodecomposition reaction, an orientation regulation by the photobinding reaction It can be divided into a photocoupled material that develops force, and a photodecomposition-coupled material that develops alignment regulation force by the occurrence of a photodecomposition reaction and a photocoupled reaction. In the present embodiment, any of the above-described photoreactive materials can be suitably used, but it is more preferable to use a photodimerization type material from the viewpoint of stability and reactivity (sensitivity).

  The photodimerization type material is not particularly limited as long as it is a material capable of expressing the alignment regulating force by the occurrence of the photodimerization reaction, but the wavelength of light causing the photodimerization reaction is 280 nm from the viewpoint that the alignment regulating force is good. It is preferable that it is the above, It is more preferable that it is in the range of 280 nm-400 nm, It is further more preferable that it is in the range of 300 nm-380 nm. Examples of such a photodimerization type material include polymers having cinnamate, coumarin, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, uracil, quinolinone, maleinimide, or a cinnamilidene acetic acid derivative. Among them, a polymer having one or both of cinnamate and coumarin is preferably used from the viewpoint of good alignment regulating power. Specific examples of such a photodimerization type material include compounds described in, for example, JP-A-9-118717, JP-T-10-506420, JP-T2003-505561, and WO2010 / 150748. Can be mentioned.

  In addition, the photo-alignment material used in this Embodiment may be only one type, and may mix and use two or more types.

(solvent)
The solvent used in the alignment film composition is not particularly limited as long as it can dissolve the above-described photo-alignment material or the like to a desired concentration. For example, hydrocarbon solvents such as benzene and hexane, methyl ethyl ketone, methyl Ketone solvents such as isobutyl ketone and cyclohexanone, ether solvents such as tetrahydrofuran, 1,2-dimethoxyethane, propylene glycol monoethyl ether (PGME), alkyl halide solvents such as chloroform and dichloromethane, methyl acetate, ethyl acetate, Ester solvents such as butyl acetate and propylene glycol monomethyl ether acetate, amide solvents such as N, N-dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, anone solvents such as cyclohexane, methanol, ethanol, It can be exemplified an alcohol solvent such as propyl alcohol. Moreover, one type of solvent may be sufficient and the mixed solvent of two or more types of solvents may be sufficient.

  Further, the amount of the solvent is not particularly limited, but is preferably about 600 to 3900 parts by mass with respect to 100 parts by mass of the photo-alignment material. If the amount of the solvent is less than 600 parts by mass, the photo-alignment material may not be dissolved uniformly. On the other hand, when the amount of the solvent exceeds 3900 parts by mass, a part of the solvent remains, and when the alignment film composition is applied onto the substrate, the remaining solvent penetrates into the substrate, As a result, both the photo-alignment property and the adhesion to the substrate may be reduced.

  The thickness of the alignment layer 12 is not particularly limited as long as it is within a range in which a desired alignment regulating force can be expressed with respect to the liquid crystal compound (polymerizable liquid crystal composition for forming a retardation layer), but is in a range of 50 nm to 1000 nm. It is preferable to be within. When the thickness of the alignment layer 12 is less than 50 nm, there is a possibility that a desired alignment regulating force cannot be expressed for the liquid crystal compound. On the other hand, if the thickness exceeds 1000 nm, the adhesion may be reduced.

<Phase difference layer (liquid crystal layer)>
The retardation layer 13 contains a polymerizable liquid crystal composition. This polymerizable liquid crystal composition contains a liquid crystal compound (rod-like compound) exhibiting liquid crystallinity and having a polymerizable functional group in the molecule. When the alignment layer 12 is composed of a pattern alignment film, since the retardation layer 13 is formed along the alignment pattern, the first retardation region corresponding to the region for the right eye and the region for the left eye And a second phase difference region corresponding to.

(Liquid crystal compound)
A polymerizable liquid crystal compound (hereinafter, also simply referred to as “liquid crystal compound”) has refractive index anisotropy and has a function of imparting a desired retardation by regularly arranging. Examples of the liquid crystal compound include materials exhibiting a liquid crystal phase such as a nematic phase and a smectic phase, but the nematic phase is easier to arrange regularly than liquid crystal compounds exhibiting other liquid crystal phases. It is more preferable to use the liquid crystal compound shown. As the liquid crystal compound exhibiting a nematic phase, it is preferable to use a material having spacers at both ends of the mesogen. Since the liquid crystal compound having spacers at both ends of the mesogen is excellent in flexibility, the retardation film 1 can be made excellent in transparency by using such a liquid crystal compound.

  The liquid crystal compound is a polymerizable liquid crystal compound having a polymerizable functional group in the molecule as described above. By having a polymerizable functional group, it is possible to polymerize and fix the liquid crystal compound, so that the alignment stability is excellent and the phase change is less likely to occur over time. The polymerizable liquid crystal compound more preferably has a polymerizable functional group capable of three-dimensional crosslinking in the molecule. By having a polymerizable functional group capable of three-dimensional crosslinking, the sequence stability can be further enhanced. Note that “three-dimensional crosslinking” means that liquid crystal molecules are polymerized three-dimensionally to form a network structure.

  Examples of the polymerizable functional group include those that are polymerized by ionizing radiation such as ultraviolet rays and electron beams. Examples of these polymerizable functional groups include radically polymerizable functional groups. Representative examples of radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, and specific examples include vinyl groups and acrylate groups with or without substituents. (Generic name including acryloyl group, methacryloyl group, acryloyloxy group, methacryloyloxy group) and the like.

  Furthermore, the polymerizable liquid crystal compound is particularly preferably one having a polymerizable functional group at the terminal. By using such a liquid crystal compound, for example, they can be polymerized three-dimensionally to form a network structure, so that they have column stability and excellent optical properties. The retardation film 1 can be formed.

  Moreover, a liquid crystal compound can be used individually by 1 type or in mixture of 2 or more types. For example, when a liquid crystal compound having one or more polymerizable functional groups at both ends and a liquid crystal compound having one or more polymerizable functional groups at one end are mixed and used as a liquid crystal compound, Polymerization density (crosslinking density) and optical characteristics can be arbitrarily adjusted. Further, from the viewpoint of ensuring reliability, it is preferable to use a polymerizable liquid crystal compound having one or more polymerizable functional groups at both ends, but from the viewpoint of liquid crystal alignment, there is one polymerizable functional group at both ends. It is preferable to use one.

  The amount of the liquid crystal compound is not particularly limited as long as the viscosity of the retardation layer forming coating liquid (liquid crystal composition) can be adjusted to a desired value according to the coating method applied on the alignment layer 12. The amount in the polymerizable liquid crystal composition is preferably in the range of 5 parts by mass to 40 parts by mass, and more preferably in the range of 10 parts by mass to 30 parts by mass. If the amount of the liquid crystal compound is less than 5 parts, the content of the liquid crystal compound is too small, so that the incident light on the retardation layer 13 may not be properly aligned. On the other hand, when it exceeds 40 parts by mass, the workability is deteriorated because the viscosity of the polymerizable liquid crystal composition becomes too high.

(Polymerization initiator)
Here, in the present embodiment, in the polymerizable liquid crystal composition, two kinds of photopolymerization initiators (first photopolymerization initiator and second photopolymerization) having absorption peak wavelengths (photosensitive wavelengths) different from each other. It is characterized by containing an initiator.

  As will be described in detail later, in this way, by containing two types of photopolymerization initiators that react at different wavelengths in the retardation layer 13, light sources that output different wavelengths (light sources having different emission wavelengths) The reaction timing of these photopolymerization initiators can be controlled. According to the retardation film 1 constituted by such a retardation layer 13, the adhesion between the retardation layer 13 and the polarizer 21 attached to the retardation film 1 can be effectively enhanced.

(solvent)
The above-described liquid crystal compound and the like are usually dissolved in a solvent. The solvent is not particularly limited as long as it can uniformly disperse liquid crystal compounds and the like. For example, hydrocarbon solvents such as benzene and hexane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, tetrahydrofuran Ether solvents such as 1,2-dimethoxyethane and propylene glycol monoethyl ether, alkyl halide solvents such as chloroform and dichloromethane, ester solvents such as methyl acetate, ethyl acetate, butyl acetate and propylene glycol monomethyl ether acetate, Examples include amide solvents such as N, N-dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, anone solvents such as cyclohexane, and alcohol solvents such as methanol, ethanol, and isopropyl alcohol. It can be, but is not limited thereto. Further, the solvent may be a single type or a mixed solvent of two or more types.

  The amount of the solvent is preferably about 66 to 900 parts by mass with respect to 100 parts by mass of the liquid crystal compound. If the amount of the solvent is less than 66 parts by mass, the liquid crystal compound may not be dissolved uniformly. On the other hand, if it exceeds 900 parts by mass, a part of the solvent may remain, reliability may be lowered, and coating may not be performed uniformly.

(Other compounds)
Further, the liquid crystal composition may contain other compounds as necessary. The other compound is not particularly limited as long as it does not impair the alignment order of the liquid crystal compound described above, and examples thereof include a surfactant.

  For example, examples of the surfactant include a fluorine-based surfactant. As the fluorosurfactant, a compound having a fluoroalkyl group or a fluoroalkylene group at at least one of the terminal, main chain, and side chain is preferable, and specific examples thereof include 1,1,2,2-tetra Fluorooctyl (1,1,2,2-tetrafluoro-n-propyl) ether, 1,1,2,2-tetrafluoro-n-octyl (n-hexyl) ether, octaethylene glycol di (1,1,1, 2,2-tetrafluoro-n-butyl) ether, hexaethylene glycol (1,1,2,2,3,3-hexafluoro-n-pentyl) ether, octapropylene glycol di (1,1,2,2) -Tetrafluoro-n-butyl) ether, hexapropylene glycol di (1,1,2,2,3,3-hexafluoro-n-penty ) Ether, 1,1,2,2,3,3-hexafluoro-n-decane, 1,1,2,2,8,8,9,9,10,10-decafluoro-n-dodecane, par Anionic surfactants such as sodium fluoro-n-dodecyl sulfonate, sodium fluoroalkylbenzene sulfonate, sodium fluoroalkyl phosphonate, sodium fluoroalkyl carboxylate, fluoroalkyl polyoxyethylene ether, diglycerin tetrakis (fluoroalkyl polyoxy Ethylene ether), perfluoroalkyl polyoxyethanol, perfluoroalkyl alkoxylates, nonionic surfactants such as fluoroalkyl esters, cationic surfactants such as fluoroalkylammonium iodide, fluoroalkylbetaines, etc. It may be mentioned amphoteric surfactants. Of these, nonionic surfactants are particularly preferably used.

  The content of such a surfactant is preferably added within a range that does not significantly impair the alignment of the liquid crystal compound, and is about 0.01 to 1 part by mass with respect to 100 parts by mass of the liquid crystal compound. It is preferable to add.

  The thickness of the retardation layer 13 is not particularly limited as long as it is within a range in which a predetermined retardation can be achieved, and can be, for example, about 500 nm to 2000 nm. Moreover, it is preferable to set the thickness so that the in-plane retardation of the retardation layer 13 corresponds to λ / 4 minutes. Here, λ is a wavelength of 500 nm as a guide. As a result, the linearly polarized light passing through the retardation layer 13 can be made into circularly polarized light orthogonal to each other, so that a three-dimensional image can be displayed with higher accuracy.

≪2. About retardation layer (liquid crystal layer) >>
(Configuration of retardation layer)
As described above, the retardation layer 13 is composed of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound exhibiting liquid crystallinity and having a polymerizable functional group in the molecule. In particular, in the retardation film 1 according to the present embodiment, two types of photopolymerization initiation having different absorption peak wavelengths (photosensitive wavelengths) are included in the polymerizable liquid crystal composition constituting the retardation layer 13. It is characterized by containing an agent.

  Here, FIG. 3 shows an absorption curve of an α-hydroxyketone compound that can be used as a photopolymerization initiator. FIG. 4 shows an absorption curve of an α-aminoketone compound that can be used as a photopolymerization initiator. FIG. 5 shows an absorption curve of a titanocene compound that can be used as a photopolymerization initiator. As shown in FIGS. 3 to 5 as an example, it can be seen that each compound that can be used as a photopolymerization initiator has various absorption peak wavelengths.

  Therefore, in the present embodiment, first, the retardation layer 13 is composed of a polymerizable liquid crystal composition containing two types of photopolymerization initiators having different absorption peak wavelengths. Specifically, for example, an α-hydroxyketone system “DAROCURE1173” having an absorption peak wavelength of 250 nm, which shows an absorption curve in FIG. 3, and an α-aminoketone system having an absorption peak wavelength of 310 nm, which is shown in FIG. Two types of “IRGACURE907” are added to the polymerizable liquid crystal composition as photopolymerization initiators.

  And in this Embodiment, after coating the coating liquid which consists of this polymeric liquid crystal composition on the orientation layer 12, the two types of photopolymerization starts by the light source (exposure device) which outputs a different wavelength. It is important to control the reaction time such as agent cleavage. That is, two types of photopolymerization initiators having different absorption peak wavelengths added to the polymerizable liquid crystal composition are controlled to react step by step by using light sources having different emission wavelengths. .

  The emission spectrum figure of the electrodeless UV lamp (product made from Fusion) generally marketed is shown to Fig.6 (a)-(d). FIG. 7 shows an emission spectrum diagram of a low-pressure mercury lamp (manufactured by GS Yuasa) that is generally commercially available. It can be seen that the electrodeless UV lamps shown in FIGS. 6A to 6D each emit light in a wide wavelength range, although each has a central emission wavelength. On the other hand, in the case of the low-pressure mercury lamp shown in FIG. 7, it can be seen that the center light emission wavelength is 250 nm, and the light emission is substantially single.

  Therefore, in the present embodiment, exposure is performed using a light source having an appropriate emission wavelength according to the absorption peak wavelengths of the two types of photopolymerization initiators added to the polymerizable liquid crystal composition constituting the retardation layer 13. Treatment is performed to control the reaction timing of these two types of photopolymerization initiators.

(Reaction control of photopolymerization initiator, adhesion improvement mechanism)
More specifically, for example, as described above, α-hydroxyketone system “DAROCURE1173” (absorption peak wavelength: 250 nm, referred to as “first photopolymerization initiator”) and α-aminoketone system “IRGACURE907” ( In the case where a coating liquid composed of a polymerizable liquid crystal composition to which two types of absorption peak wavelength: 310 nm and “second photopolymerization initiator” are added is applied onto the alignment layer 12, first, the emission wavelength is Exposure processing is performed using a light source having a single wavelength of 250 nm (for example, a low-pressure mercury lamp whose emission spectrum is shown in FIG. 7). As a result, the α-hydroxyketone-based “first photopolymerization initiator” contained in the polymerizable liquid crystal composition reacts, and a crosslinking polymerization reaction of the polymerizable liquid crystal compound occurs to cure the coating film. Thus, the retardation layer 13 is formed. At this time, the α-aminoketone-based second photopolymerization initiator, which is another type of photopolymerization initiator contained in the polymerizable liquid crystal composition, has a phase difference of 310 nm due to its absorption peak wavelength of 310 nm. It does not react with a single wavelength light source having an emission wavelength of 250 nm used for curing the coating film of the layer 13 and remains in the retardation layer 13.

  Next, with respect to the retardation film 1 in which the coating film of the polymerizable liquid crystal composition is cured in this way to form the retardation layer 13, an adhesive such as a UV adhesive is adhered to the surface of the retardation layer 13. The agent composition is applied, and the polarizer 21 is laminated through the adhesive composition. And after laminating | stacking the polarizer 21, an exposure process is performed based on a predetermined light source (exposure device). At this time, in the retardation layer 13, the monomer component in the adhesive composition penetrates into the retardation layer 13 by applying the adhesive composition. In this state, the absorption peak wavelength of the second photopolymerization initiator (α-aminoketone system) that is added to the polymerizable liquid crystal compound and remains in the retardation layer 13 without reacting is determined as the emission wavelength. The exposure process is performed using the exposure apparatus included in the above. Then, by this exposure treatment, a curing reaction of the adhesive composition occurs to form the adhesive layer 20, and the second photopolymerization initiator remaining in the retardation layer 13 reacts. The monomer component that has penetrated into the retardation layer 13 is polymerized by causing a polymerization reaction, and this improves the adhesion between the retardation layer 13 and the polarizer 21 via the adhesive layer 20. .

  In the present embodiment, in this way, the retardation film 1 is prepared by adding two types of photopolymerization initiators having different absorption peak wavelengths to the retardation layer 13, and adhered to the retardation film 1. The polarizer 21 is pasted through the agent layer 20. Thereby, the adhesiveness between the retardation layer 13 and the polarizer 21 in the retardation film 1 can be effectively enhanced via the adhesive layer 20.

  In addition, in the exposure processing after laminating the polarizer 21, the absorption peak wavelength of the second photopolymerization initiator remaining in the retardation layer 13 is included in the emission wavelength, and the curing reaction of the adhesive composition is performed. A light source (exposure apparatus) having an emission wavelength that also occurs is appropriately selected. For example, it is preferable to use an electrodeless UV lamp having an emission spectrum in a wide wavelength range as shown in the emission spectrum of FIG.

(Photopolymerization initiator)
As described above, as the photopolymerization initiator, two types having different absorption peak wavelengths are selected and added to the polymerizable liquid crystal composition.

  The photopolymerization initiator is not particularly limited as long as it causes a reaction such as cleavage upon irradiation with active energy rays such as ultraviolet rays and initiates the polymerization reaction. For example, as illustrated in FIGS. Things can be used. More specifically, for example, benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamine) benzophenone, α-amino acetophenone, 4,4-dichlorobenzophenone 4-benzoyl-4-methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, p-tert -Butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyldimethyl ketal, benzylmethoxyethyl acetal, benzoin methyl Ether, benzoin butyl ether, anthraquinone, 2-tert-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzsuberon, methyleneanthrone, 4-azidobenzylacetophenone, 2,6-bis (p-azidobenzylidene) ) Cyclohexane, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2- ( o-ethoxycarbonyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime, L-ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, naphthalenesulfonyl chloride , Quinolinesulfonyl chloride, n-phenylthioacridone, 4,4-azobisisobutyronitrile, diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, camphorquinone, N1717 manufactured by Adeka, carbon tetrabromide, tribromophenyl Examples include sulfone and benzoin peroxide.

  Among these exemplified photopolymerization initiators, any one of the two types is preferably a photopolymerization initiator in which the emission wavelength of a light source having a single emission wavelength is the absorption peak wavelength. For example, in the case of the low-pressure mercury lamp whose emission spectrum is shown in FIG. 7, it emits light at a substantially single wavelength with a central emission wavelength of 250 nm, and is adapted to a light source showing such a single emission wavelength. For example, it is preferable to select a photopolymerization initiator having an absorption peak wavelength at 250 nm as one of the two types (especially, the first photopolymerization initiator). Thereby, control of reaction of the photoinitiator mentioned above can be performed effectively, and the adhesiveness of the phase difference layer 13 and the polarizer 21 can be improved more effectively.

  In selecting two types of photopolymerization initiators, there is no particular limitation as long as two types having different absorption peak wavelengths are selected as described above, but the difference between the absorption peak wavelengths is preferably 30 nm or more, and 50 nm. More preferably, the difference is as described above. As described above, the difference in absorption peak wavelength between the two types of photopolymerization initiators is preferably 30 nm or more, more preferably 50 nm or more, so that the reaction of these photopolymerization initiators can be controlled more effectively. The adhesion between the retardation layer 13 and the polarizer 21 can be further enhanced.

  The content of the photopolymerization initiator in the polymerizable liquid crystal composition is not particularly limited as long as it does not significantly impair the alignment of the liquid crystal compound, but each photopolymerization initiator is added to 100 parts by mass of the liquid crystal compound. The content is preferably in the range of about 0.1 to 10 parts by mass, more preferably in the range of about 0.5 to 7 parts by mass, and the range of about 1 to 5 parts by mass. It is particularly preferred that When the content of each photopolymerization initiator is less than 0.1 parts by mass with respect to 100 parts by mass of the liquid crystal compound, a sufficient polymerization reaction cannot be caused, and reaction control of two types of photopolymerization initiators There is a possibility that the effect of improving the adhesion between the retardation layer 13 based on the above and the polarizer 21 cannot be obtained. On the other hand, when the content of each photopolymerization initiator exceeds 10 parts by mass, the retardation layer may be discolored, which may affect the alignment of the liquid crystal compound.

≪3. Production method of retardation film, production method of optical film >>
Hereinafter, the manufacturing method of the retardation film 1 mentioned above and the manufacturing method of the optical film 2 which affixed the polarizer 21 to the retardation film 1 are demonstrated.

<Method for producing retardation film>
FIG. 8 is a flowchart showing the flow of the method for producing the retardation film 1 (retardation film production step S1). As shown in FIG. 8, the retardation film 1 is first provided with a substrate 11 made of a long transparent film material wound around a roll (S11).

  Next, in alignment layer formation process S12, the base material 11 is sent out from a roller, and the coating liquid (alignment film composition) for alignment layer formation is applied on the base material 11, for example, photo-alignment material film etc. An alignment film made of is formed on the substrate 11. For example, the photo-alignment material film can be produced by applying various film-forming methods and applying a film-forming liquid obtained by dissolving the photo-alignment material in a solvent such as benzene by a die coating method or the like and then drying the film-forming liquid. . And after that, the alignment layer 12 is formed by irradiating and hardening | curing an ultraviolet-ray by exposure process.

  Next, after drying the coating film obtained by coating the alignment layer 12, the light source (exposure device) having a predetermined emission wavelength and a wire grid are used to irradiate polarized ultraviolet rays to achieve a predetermined alignment regulating force. Hold in place.

  The coating method of the coating liquid is not particularly limited. For example, in addition to the above-described die coating method, gravure coating method, reverse coating method, knife coating method, dip coating method, spray coating method, air knife coating Methods such as spin coating, roll coating, printing, dipping and lifting, curtain coating, casting, bar coating, extrusion coating, and E-type coating can be used.

  Next, in the polymerizable liquid crystal composition coating step S13, a coating liquid of a polymerizable liquid crystal composition containing a liquid crystal compound (a coating liquid for forming a retardation layer) is applied on the alignment layer 12, and then The coating solution is dried using a dryer or the like. In addition, after apply | coating a coating liquid on the orientation layer 12, you may make it perform the leveling process for making the layer thickness of the phase difference layer 13 formed uniform.

  In this polymerizable liquid crystal composition coating step S13, the liquid crystal compound is aligned in a desired direction by drying the coating liquid (coating film) of the polymerizable liquid crystal composition coated on the alignment layer 12. Can do. The conditions for the drying treatment are not particularly limited as long as the liquid crystal compound can be heated to the liquid crystal phase formation temperature or higher, and may be appropriately adjusted according to the amount of the solvent remaining in the coating film. For example, the wind speed of the dry wind applied to the coating film can be 3 m / second or less, and preferably 0.5 m / second or less.

  Further, the temperature condition for the drying treatment depends on the liquid crystal → isotropic phase transition temperature of the liquid crystal compound used, but it can be, for example, in the range of about 40 ° C. to 150 ° C., preferably 50 ° C. to 120 ° C. And more preferably within the range of 55 ° C to 110 ° C. Further, the drying time can be, for example, in the range of about 0.2 minutes to 30 minutes, preferably in the range of 0.5 minutes to 20 minutes, and more preferably in the range of 1 minute to 10 minutes. It can be. By setting it as such dry conditions, the solvent in a coating film can be removed stably.

  In addition, as a coating method of the coating liquid of the polymerizable liquid crystal composition, it can be performed by a die coating method, a gravure coating method, or the like, similarly to the coating method of the alignment film composition.

  Next, after drying the coating film obtained by coating the polymerizable liquid crystal composition, in the retardation layer forming step (curing treatment step) S14, a light source (exposure device) having a predetermined emission wavelength is used. By irradiating active energy rays such as ultraviolet rays and performing an exposure treatment, the coating film of the polymerizable liquid crystal composition is cured to form the retardation layer (liquid crystal layer) 13.

  Here, in this embodiment, as described above, two types of photopolymerization initiators having different absorption peak wavelengths (photosensitive wavelengths) are included in the polymerizable liquid crystal composition applied onto the alignment layer 12. And the retardation layer 13 is formed thereby. In the present embodiment, first, in this curing treatment step S14, the absorption peak wavelength of the first photopolymerization initiator of the two types of photopolymerization initiators contained in the polymerizable liquid crystal composition is determined. An exposure process is performed using a light source (exposure apparatus) that irradiates an active energy ray (such as ultraviolet rays) that is included as an emission wavelength and does not include the absorption peak wavelength of the second photopolymerization initiator as an emission wavelength.

  As a result, in the curing treatment step S14, only the first photopolymerization initiator contained in the polymerizable liquid crystal composition reacts, and the polymerizable liquid crystal compound is changed based on the reaction of the photopolymerization initiator. A cross-linking polymerization reaction occurs, the coating film is cured, and the retardation layer 13 is formed. At this time, the second photopolymerization initiator, which is another type of photopolymerization initiator, contained in the polymerizable liquid crystal composition absorbs a wavelength different from the emission wavelength of the exposure apparatus used for the curing process. Since it has a peak wavelength, it remains in the retardation layer 13 without reacting.

  As a light source for active energy rays, for example, when irradiating ultraviolet rays, a light source having a predetermined emission wavelength as shown in FIGS. 6 and 7 can be used. More specifically, for example, low-pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), high-pressure discharge lamp (high-pressure mercury lamp, metal halide lamp), short arc discharge lamp (ultra-high pressure mercury lamp, xenon lamp, mercury xenon) Lamp) and the like. Note that the same light source can also be used in the exposure process in the alignment layer forming step (S12).

In addition, as the irradiation amount (integrated light amount) of the active energy ray, the photopolymerization initiator added to the polymerizable liquid crystal composition is effectively caused to undergo a reaction such as cleavage to effectively cause a crosslinking polymerization reaction. Although not particularly limited as possible, for ^example, it is preferably in the range of ^{5mJ / cm 2 ~500mJ / cm 2} , and more preferably in a range of ^{7mJ / cm 2 ~300mJ / cm 2} .

  Moreover, when irradiating active energy rays, such as an ultraviolet-ray, with respect to a coating film, it is preferable to adjust temperature so that the temperature of the coating film may become fixed. As temperature of a thin film, it is preferable that it is 15 to 90 degreeC, and it is more preferable that it is 15 to 60 degreeC. Examples of the temperature control method include a method using a temperature control device such as a general heating / cooling device.

  By performing the curing treatment as described above, the liquid crystal compounds in the polymerizable liquid crystal composition can be polymerized to form a network structure, have column stability, and have optical properties. The retardation layer 13 having excellent expression can be formed. By forming the retardation layer 13, a film in which the substrate 11 / alignment layer 12 / retardation layer 13 are laminated in this order can be produced. In addition, after winding up the obtained film with a winding reel etc., the retardation film 1 is produced by performing the cutting process which cuts out to a desired magnitude | size.

<Method for producing optical film>
Then, the manufacturing method of the optical film 2 which affixed the polarizer 21 on the phase difference film 1 manufactured as mentioned above is demonstrated. FIG. 9 is a flowchart showing the flow of the manufacturing process of the optical film 2. In addition, it shows to a flowchart with the manufacturing process (retardation film preparation process S1) of the retardation film 1 mentioned above.

  As shown in FIG. 9, after producing the retardation film 1 (after the retardation film production step S1), in the polarizer laminating step S2, UV adhesion is performed on the surface of the retardation layer 13 of the retardation film 1. An adhesive composition constituting the adhesive layer 20 made of an agent or the like is applied, and then a polarizer 21 is laminated on the applied adhesive composition (uncured adhesive composition). At this time, in this embodiment, the monomer component in the adhesive composition penetrates into the retardation layer 13 by applying the adhesive composition to the surface of the retardation layer 13. The uncured state is a state before completion of curing, and may be completely uncured or partially cured.

  Next, in a state where the polarizer 21 is laminated on the adhesive composition, an active energy ray such as ultraviolet rays is irradiated using a light source having a predetermined emission wavelength in the adhesive layer forming step (curing treatment step) S3. By doing so, the coating film of adhesive composition is hardened and the adhesive bond layer 20 is formed.

  Here, as described above, in the retardation layer 13, the monomer component in the adhesive composition penetrates into the retardation layer 13, and another type of photopolymerization initiator added to the polymerizable liquid crystal compound. The second photopolymerization initiator is left unreacted. Therefore, in the adhesive layer forming step S3, the emission wavelength that includes the absorption peak wavelength of the second photopolymerization initiator remaining in the retardation layer 13 in the emission wavelength and also causes the curing reaction of the adhesive composition. An exposure process is performed using a light source (exposure apparatus) having Then, the second photopolymerization initiator remaining in the retardation layer 13 reacts by this exposure treatment, and a polymerization reaction is caused to the monomer component that has penetrated into the retardation layer 13 to be polymerized. It becomes like this. At the same time, the coating film of the adhesive composition is cured to form the adhesive layer 20. In the present embodiment, the retardation layer 13 and the polarizer 21 in the retardation film 1 are in close contact with each other through the adhesive layer 20 made of the adhesive composition.

  Based on the above process, the optical film 2 which bonded the polarizer 21 to the phase difference film 1 can be produced. In particular, the optical film 2 according to the present embodiment uses the retardation film 1 in which the retardation layer 13 contains two types of photopolymerization initiators having different absorption peak wavelengths. Therefore, as described above, even in a high temperature and high humidity environment, the separation between the retardation layer 13 and the polarizer 21 is suppressed, and the polarizer 21 is bonded with high adhesion. Can. In addition, since the separation between the retardation layer 13 and the polarizer 21 can be suppressed as described above, the reworkability can be improved.

  Moreover, in the optical film 2 which concerns on this Embodiment, when bonding retardation film and a polarizer like the past, a protective film, a primer, etc. are not interposed. From this, the thickness of the entire optical film can be made thinner by the amount of the protective film and primer laminated, and it can fully meet the recent demands for thinning optical films.

  Further, for example, in an optical film in which a retardation film and a polarizer are laminated via a primer layer disclosed in Patent Document 1, when the alignment layer in the retardation film is composed of a pattern alignment film, it is three-dimensional. There is a tendency that the dimension of an important pattern is difficult to control when displaying. On the other hand, in the optical film 2, since the primer layer or the like is not used, the pattern in the formed alignment layer can be easily controlled to a desired dimension.

≪Preparation of polymerizable liquid crystal composition, production of retardation film and optical film≫
[Example 1]
First, an alignment film composition is prepared by dissolving 100 parts by mass of a photo-alignment material (trade name: ROP-103, manufactured by Lorick) having 900 parts by mass of methyl ethyl ketone (MEK) as a solvent. I got a thing. As the base material, a TAC base material (trade name: TD60UL-P, thickness: 60 μm, manufactured by Fuji Film Co., Ltd.) having an antiglare treatment on the surface is used, and the conveyance speed is set to 12 m / min. The alignment film composition was applied to the back surface by a die coating method so that the film thickness after curing was 200 nm. Then, it was allowed to flow in a dryer adjusted to 100 ° C. for 2 minutes to evaporate the solvent and to thermally cure the alignment film composition. Thereby, a thin film (alignment film) having a thickness of 200 nm was formed.

Next, a stripe pattern having a width of 500 μm is formed on the formed thin film in a direction parallel to the transport direction of the original film by applying polarized ultraviolet light (polarization axis is 45 ° with respect to the transport direction of the film) through a wire grid. Irradiation was performed through a mask formed of chromium on synthetic quartz. Subsequently, the alignment layer was formed by irradiating polarized ultraviolet rays (with the polarization axis being −45 ° with respect to the film transport direction) passing through a wire grid without passing through a mask to cure the thin film. As the ultraviolet irradiation device, “H bulb” (manufactured by Fusion) was used. The wavelength of polarized ultraviolet light was 313 nm, and the integrated light quantity was 40 mJ / cm ² . The integrated light quantity was measured using an ultraviolet light quantity meter “UV-351” (manufactured by Oak Manufacturing Co., Ltd.).

  Subsequently, it contains a polymerizable liquid crystal compound represented by the following formula (1), and further, as a photopolymerization initiator, an α-hydroxyketone photopolymerization initiator (IRGACURE184, absorption peak wavelength: 250 nm), and an α-aminoketone. Two types of photopolymerization initiators (IRGACURE907, absorption peak wavelength: 310 nm) were added so as to have a weight ratio of 3% with respect to the polymerizable liquid crystal compound to prepare a polymerizable liquid crystal composition.

This polymerizable liquid crystal composition was applied on the alignment layer by a die coating method and leveled so that the final layer thickness was 1 μm. Then, it flows for 1 minute in the first dryer adjusted to 60 ° C., 0.5 minute in the second dryer adjusted to 95 ° C., and 0.5 minute in the third dryer adjusted to 105 ° C. Cooled to near. And after that, it exposed using the ultraviolet irradiation device and formed the phase difference layer (liquid crystal layer), and obtained the phase difference film. Specifically, a low-pressure mercury lamp (center wavelength: 254 nm, manufactured by GS Yuasa) was used as an ultraviolet irradiation device, and irradiation was performed until the integrated light amount reached 300 mJ / cm ² .

  Next, polarized light obtained by immersing a polyvinyl alcohol film, which is a hydrophilic polymer film, in an iodine / potassium iodide aqueous solution (concentration 0.3%) as a polarizer and then uniaxially stretching the film, followed by drying. Prepared the child. Further, as the adhesive, a maleic anhydride-vinyl ethyl ether copolymer, which is a carboxylic acid-containing polymer, was stirred in hot water at 80 ° C. to prepare a photocuring adhesive solution having a solid concentration of 10% by weight. And with respect to the produced retardation film, after applying the prepared photocuring adhesive on the surface of the retardation layer and attaching a polarizer via the adhesive, an ultraviolet irradiation device is used. Exposed. At this time, as an ultraviolet irradiation device, an electrodeless UV lamp (H bulb, manufactured by Fusion UV Systems) was used for curing. This produced the optical film which stuck the polarizer on the phase difference film.

[Example 2]
In Example 2, the polymerizable liquid crystal composition includes a polymerizable liquid crystal compound represented by the above formula (1), and an α-hydroxyketone photopolymerization initiator (DAROCURE 1173, absorption peak) as a photopolymerization initiator. And a titanocene photopolymerization initiator (IRGACURE 727L, absorption peak wavelength: 410 nm), both of which were added so as to have a weight ratio of 3% with respect to the polymerizable liquid crystal compound. And using this polymeric liquid crystal composition, it apply | coated on the orientation layer by the die-coating method, and performed the drying process. The operating conditions other than the polymerizable liquid crystal composition were the same as in Example 1.

Then, it exposed using the ultraviolet irradiation device and formed the phase difference layer (liquid crystal layer), and obtained the phase difference film. As an ultraviolet irradiation device, a low-pressure mercury lamp (center wavelength: 254 nm, manufactured by GS YUASA) was used, and irradiation was performed until the integrated light amount reached 300 mJ / cm ² .

  Next, the polarizer was affixed with respect to the produced retardation film using the same polarizer and photocuring adhesive as Example 1. FIG. At this time, in Example 2, it exposed and hardened using the argon laser irradiation apparatus (Innova 300C, Coherent Japan make) whose center wavelength is 488 nm. This produced the optical film which stuck the polarizer on the phase difference film.

[Comparative Example 1]
In Comparative Example 1, the polymerizable liquid crystal composition contains the polymerizable liquid crystal compound represented by the above formula (1), and only the α-hydroxyketone photopolymerization initiator (IRGACURE184) is used as the photopolymerization initiator. It was prepared by adding so that the ratio by weight to the liquid crystal compound was 3%. Using this polymerizable liquid crystal composition, it was applied on the alignment layer by a die coating method and subjected to a drying treatment. The operating conditions other than the polymerizable liquid crystal composition were the same as in Example 1.

Then, it exposed using the ultraviolet irradiation device and formed the phase difference layer (liquid crystal layer), and obtained the phase difference film. As an ultraviolet irradiation device, an electrodeless UV lamp (H bulb, manufactured by Fusion UV Systems) was used, and irradiation was performed until the integrated light amount reached 300 mJ / cm ² .

  Next, the polarizer was affixed with respect to the produced retardation film using the same polarizer and photocuring adhesive as Example 1. FIG. At this time, it exposed and hardened using the same ultraviolet irradiation device (H bulb) as what was used at the time of phase contrast layer formation. This produced the optical film which stuck the polarizer on the phase difference film.

≪Adhesion evaluation≫
For the optical films produced in Examples 1 and 2 and Comparative Example 1, the adhesion between the retardation layer (liquid crystal layer) of the retardation film and the polarizer was evaluated. The evaluation of adhesion was performed by carrying out a crosscut according to JIS K5400-8.5 method using a mending tape (manufactured by Sumitomo 3M).

  As a result, in the optical films of Examples 1 and 2, the retardation layer and / or the polarizer were both broken and could not be peeled off. On the other hand, in the optical film of the comparative example 1, it peeled completely between the phase difference layer and the polarizer. From this result, it can be seen that in the optical films of Examples 1 and 2, the adhesion between the retardation layer and the polarizer is very high.

DESCRIPTION OF SYMBOLS 1 Retardation film 2 Optical film 11 Base material 12 Orientation layer 13 Retardation layer 20 Adhesive layer 21 Polarizer

Claims (4)

A substrate, an alignment layer, and a retardation layer containing a polymerizable liquid crystal compound are laminated in this order,
The retardation film is composed of a polymerizable liquid crystal composition containing two kinds of photopolymerization initiators having absorption peak wavelengths different from each other. A retardation film is formed by laminating a base material, an alignment layer, and a retardation layer containing a polymerizable liquid crystal compound in this order, and a polarizer is laminated on the surface of the retardation layer via an adhesive layer. Become
The optical film, wherein the retardation layer is composed of a polymerizable liquid crystal composition containing two kinds of photopolymerization initiators having absorption peak wavelengths different from each other. For a retardation film in which a base material, an alignment layer, and a retardation layer containing a polymerizable liquid crystal compound are laminated in this order, a polarizer is laminated on the surface of the retardation layer via an adhesive layer. A method for producing an optical film obtained by:
A liquid crystal composition coating step for coating a polymerizable liquid crystal composition containing the polymerizable liquid crystal compound and two kinds of photopolymerization initiators having different absorption peak wavelengths on the alignment layer;
A retardation layer is formed by curing a coating film of the polymerizable liquid crystal composition using a first light source that irradiates ultraviolet rays that react only with the first photopolymerization initiator among the photopolymerization initiators. A retardation layer forming step,
A polarizer laminating step in which an adhesive composition is applied to the surface of the retardation layer of the retardation film obtained by forming the retardation layer, and a polarizer is laminated on the coating film of the adhesive composition. When,
Using a second light source that includes an absorption peak wavelength of the second photopolymerization initiator of the photopolymerization initiator as an emission wavelength and irradiates ultraviolet rays having an emission wavelength that cures the adhesive composition, An adhesive layer forming step of forming an adhesive layer by curing a coating film of the adhesive composition.   In the retardation layer forming step, a light source having an emission wavelength including the absorption peak wavelength of the first photopolymerization initiator and excluding the absorption peak wavelength of the second photopolymerization initiator is used as the first light source. The method for producing an optical film according to claim 3.

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