JP2008209733A - Optical film, manufacturing method and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film hardly causing wrinkles and curls even when being not firmly stuck to a substrate, to provide its manufacturing method, and to provide a liquid crystal display device hardly causing the aging degradation of optical performance and capable of being easily recycled. <P>SOLUTION: The optical film is provided with a first transparent polymer film, an alignment layer, a selective reflection layer, a retardation layer and a second transparent polymer film in this order. The first transparent polymer film and the second transparent polymer film are made of the same material and thickness A of the first transparent polymer film and thickness B of the second transparent polymer film have a relation: (0.8A)≤B≤(1.2A). The manufacturing method of the optical film adopts a roll-to-roll process, and the liquid crystal display device comprises the optical film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical film, a method for producing the same, and a liquid crystal display device.

  Various optical films are provided in a display device such as a liquid crystal display device. For example, in order to improve the luminance of a liquid crystal display device, an optical film including a selective reflection layer and a retardation layer is widely provided between a backlight and a liquid crystal cell. More specifically, a brightness enhancement film in which an orientation layer, a polarization separation layer, and a retardation layer are provided on a base film such as a transparent polymer film is used.

  Such an optical film usually does not have rigidity capable of maintaining a flat plate state by itself, and therefore, when it is simply placed in the apparatus, wrinkles and curls are likely to occur over time, and display image quality is likely to deteriorate. Therefore, when this is provided in a liquid crystal display device, it is generally attached to a highly rigid substrate such as a liquid crystal cell substrate directly or via another layer such as a polarizing plate (for example, a patent Reference 1). In order to maintain the flat state of the film, the film is generally firmly attached so as not to easily peel off.

  The board is required to be recycled in the same manner as other components in order to reduce the environmental burden and to meet the requirements for the specific household equipment re-commercialization law (so-called home appliance recycling law). However, as described above, in order to recycle the substrate on which the optical film is firmly attached, a difficult process of peeling the film is required. Therefore, it is difficult to recycle the film-integrated substrate, and most of the substrate is disposed as landfill as industrial waste, resulting in a large environmental load.

  As a method for suppressing the generation of wrinkles and curls without attaching a film, it is known to fix the film on a substrate with a member such as a fixing pin and a frame (see, for example, Patent Document 2). However, when a conventional film is fixed by such a fixing method, wrinkles and curls are still likely to occur compared to a case where the film is firmly attached, and the performance is inferior.

JP 2003-149634 A JP-A-11-281966

  An object of the present invention is to provide an optical film that is less likely to cause wrinkles and curls even if it is not firmly attached to a substrate, and a method for producing the same.

  Another object of the present invention is to provide a liquid crystal display device that is unlikely to deteriorate with time in optical performance and is easy to recycle.

  As a result of intensive studies by the inventors of the present invention to solve the above problems, in the optical film having the selective reflection layer and the first transparent polymer film that supports the selective reflection layer, the first transparent polymer film of the optical film is obtained. It has been found that the above problem can be solved by further providing a second transparent polymer film made of the same material as the first transparent polymer film on the surface opposite to the surface having the present invention, and the present invention has been completed.

That is, according to the present invention, the following is provided:
[1] An optical film comprising a first transparent polymer film, an alignment film, a selective reflection layer, a retardation layer, and a second transparent polymer film in this order, the first transparent polymer film and the The second transparent polymer film is made of the same material, and the thickness A of the first transparent polymer film and the thickness B of the second transparent polymer film are (0.8A) ≦ B ≦ (1. An optical film having the relationship 2A).
[2] Each of the first transparent polymer film and the second transparent polymer film is a resin film having an alicyclic structure having a thickness of 50 to 250 μm. The optical film as described.
[3] The method for producing an optical film according to [1] or [2], wherein the first laminated film including the first transparent polymer film, the alignment film, and the selective reflection layer; A method for producing an optical film, comprising: attaching a retardation layer and a second laminated film including the second transparent polymer film by roll-to-roll.
[4] A liquid crystal display device comprising the optical film according to [1] or [2].

  Since the optical film of the present invention is less likely to cause wrinkles and curls, it can exhibit good optical performance for a long time in a liquid crystal display device even if it is not firmly attached to a substrate. Therefore, the liquid crystal display device of the present invention including the optical film of the present invention is unlikely to deteriorate with time in optical performance and can be easily recycled.

  The optical film of the present invention includes a first transparent polymer film, an alignment film, a selective reflection layer, a retardation layer, and a second transparent polymer film in this order, and the first transparent polymer film and the first transparent polymer film are arranged in this order. The two transparent polymer films are made of the same material.

(Transparent polymer film)
In the present invention, the transparent polymer film is a film made of a transparent polymer compound. In particular, the first transparent polymer film is a film that can function as a support for the alignment film, the selective reflection layer, and the like. Here, the transparent polymer compound is not particularly limited as long as it has a light transmittance necessary for an optical film, but specifically, for example, when a molded body having a thickness of 1 mm is formed. Any compound having a total light transmittance of 80% or more, preferably 90% or more can be used without particular limitation.
In the transparent polymer film used in the present invention, optical properties other than the transparency are not particularly limited, but an optically isotropic film can be preferably used. For example, the retardation Re in the in-plane direction of the transparent polymer film can be in the range of | Re | ≦ 4 nm.
The material constituting the first transparent polymer film and the second transparent polymer film is the same material.
In the present invention, “the same material” means that the monomers constituting the polymer are the same, and the linear expansion coefficient between the first transparent polymer film and the second transparent polymer film (measured according to JIS K7197). Value) is 2.0 × 10 ⁻⁵ (1 / ° C.) or less, preferably 1.0 × 10 ⁻⁵ (1 / ° C.) or less, and the first transparent polymer film It means that the absolute value of the difference in moisture permeability with the second transparent polymer film is within a range of ± 0.5 g / m ² · 24 hr.

  Specifically, as the transparent polymer constituting the transparent polymer film, a resin having an alicyclic structure can be preferably used.

  The resin having an alicyclic structure is a resin having an alicyclic structure in the main chain and / or side chain. From the viewpoint of excellent mechanical strength and heat resistance, a resin containing an alicyclic structure in the main chain is particularly preferable. Examples of the alicyclic structure include a saturated cyclic hydrocarbon (cycloalkane) structure and an unsaturated cyclic hydrocarbon (cycloalkene, cycloalkyne) structure. From the viewpoint of mechanical strength, heat resistance and the like, a cycloalkane structure and a cycloalkene structure are preferable, and among them, a cycloalkane structure is most preferable. When the number of carbon atoms constituting the alicyclic structure is usually in the range of 4 to 30, preferably 5 to 20, more preferably 5 to 15, the desired characteristics are highly balanced and suitable. is there.

  The proportion of the repeating unit having an alicyclic structure in the resin having an alicyclic structure may be appropriately selected according to the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90%. % By weight or more. When the ratio of the repeating unit having an alicyclic structure is too small, the heat resistance is lowered, which is not preferable. In addition, repeating units other than the repeating unit which has an alicyclic structure in resin which has an alicyclic structure are suitably selected according to the intended purpose.

  Specific examples of the resin having an alicyclic structure include (1) a ring-opening polymer of a norbornene monomer and a ring-opening copolymer of the norbornene monomer and other monomers capable of ring-opening copolymerization Norbornene polymers such as hydrogenated products, addition polymers of norbornene monomers, and addition copolymers of norbornene monomers with other monomers copolymerizable therewith; (2) Monocyclic olefin polymer and hydrogenated product thereof; (3) Cyclic conjugated diene polymer and hydrogenated product thereof; (4) Polymer of vinyl alicyclic hydrocarbon monomer and vinyl alicyclic hydrocarbon Copolymers of monomers and other monomers copolymerizable therewith, as well as hydrogenated products thereof, aromatic ring hydrogenated products of vinyl aromatic monomers, and vinyl aromatic monomers. Copolymerization of the monomer and other monomers copolymerizable therewith Vinyl alicyclic hydrocarbon polymers such as hydrogenated products of the body of the aromatic ring; and the like.

  Among these, from the viewpoint of obtaining desired properties, norbornene polymers and vinyl alicyclic hydrocarbon polymers are preferable. Hydrogenated ring-opening polymers of norbornene monomers, norbornene monomers and ring-opening copolymers thereof are preferred. Hydrogenated ring-opening copolymer with other polymerizable monomers, aromatic hydrogenated polymer of vinyl aromatic monomer, and other copolymerizable with vinyl aromatic monomer A hydrogenated product of an aromatic ring of a copolymer with a monomer of is more preferable.

  The method for making the resin having the alicyclic structure into a transparent polymer film is not particularly limited, and known methods such as a solvent casting method and a melt extrusion method can be applied.

  In the optical film of the present invention, the thickness A of the first transparent polymer film and the thickness B of the second transparent polymer film have a relationship of (0.8A) ≦ B ≦ (1.2A). . By having such a relationship, generation of wrinkles and curls can be prevented. The thicknesses A and B are each preferably in the range of 50 to 250 μm.

  In the optical film of the present invention, the first transparent polymer film and the second transparent polymer film are usually provided one by one with the laminated structure of the alignment film, the selective reflection layer, and the retardation layer interposed therebetween. Each of the first transparent polymer film and the second transparent polymer film may be provided in two or more layers. For example, a structure having two layers each of a first transparent polymer film and a second transparent polymer film, that is, a first transparent polymer film-first transparent polymer film-alignment film-selective reflection layer-retardation It may have a laminated structure of layer-second transparent polymer film-second transparent polymer film. In this case, the thickness A can be the sum of the thicknesses of the plurality of first transparent polymer films, and the thickness B can be the sum of the thicknesses of the plurality of second transparent polymer films.

(Alignment film)
In the present invention, the alignment film is a layer having a function of aligning the liquid crystalline compound applied thereon in a predetermined direction. In the manufacturing process of the optical film of the present invention, the selective reflection layer can be formed on the alignment film by aligning and polymerizing a polymerizable monomer constituting the selective reflection layer described later on the alignment film.
The alignment film used in the present invention is not particularly limited, and a film made of a known resin usually used as an alignment film, such as polyvinyl alcohol, polyamide, or polyimide, can be used. Such a resin can be used as the transparent polymer. It can be prepared by coating on a film and curing. The average thickness of the alignment film is preferably in the range of 0.05 μm to 2 μm, and more preferably in the range of 0.1 μm to 1 μm. The average thickness of the alignment film is obtained by measuring the thickness of the alignment film at three points along the width direction of the sheet at the middle position of the total length in the longitudinal direction of the alignment film sheet, and obtaining the average value. Value. The three points in the width direction are three points, that is, an intermediate point in the width direction of the sheet and two points located on the inner side by 10% of the total width from each end of both ends.

(Selective reflection layer)
In the present invention, the selective reflection layer is a layer having a property of transmitting specific polarized light and reflecting other polarized light. In particular, a layer that transmits predetermined circularly polarized light and reflects other circularly polarized light can be preferably used. By using such a layer in combination with the retardation layer, it is possible to exhibit a preferable function in a liquid crystal display device that transmits specific linearly polarized light with high luminance.
As the selective reflection layer, a known layer such as a layer obtained by aligning and polymerizing a polymerizable monomer capable of exhibiting a cholesteric liquid crystal phase can be used. Such a selective reflection layer can be obtained by applying a solution containing the polymerizable monomer onto the alignment film that has been subjected to a rubbing treatment, if necessary, followed by an orientation treatment followed by curing. The thickness of the selective reflection layer is preferably 1 to 100 μm, more preferably 1 to 50 μm, and even more preferably 1 to 20 μm.

(Retardation layer)
In the present invention, the retardation layer is an in-plane retardation Re (hereinafter sometimes abbreviated as “Re”) that is substantially a quarter of transmitted light, and a thickness direction retardation Rth ( Hereinafter, it may be abbreviated as “Rth”. Here, the wavelength range of the transmitted light can be a desired range required for the brightness enhancement film, and specifically, is, for example, 400 nm to 700 nm. Further, the retardation Re in the in-plane direction is approximately a quarter of the transmitted light means that the Re value is ± 65 nm from a value of 1/4 of the central value in the central value of the wavelength range of the transmitted light, Preferably it means ± 30 nm, more preferably ± 10 nm. The value of retardation Rth in the thickness direction is preferably −30 nm to −1000 nm, more preferably −50 nm to −300 nm, in the central value of the wavelength range of transmitted light.
As the retardation layer, a resin layer or the like obtained by stretching a single layer or multiple layers of resin to give optical anisotropy can be used. Preferably, a layer B1 made of a thermoplastic resin, a layer A made of a resin having a negative intrinsic birefringence value, and a layer B2 made of a thermoplastic resin are laminated in this order, and the average thickness / layer A of the layer B1 The ratio of the average thickness of the film is 3/1 to 1/3, the ratio of the average thickness of the layer A / the average thickness of the layer B2 is 1/3 to 3/1, and the MD direction (of the long film A long retardation film having a slow axis facing in a direction inclined by 25 to 65 degrees with respect to (longitudinal direction) is preferable.

  Examples of the resin having a negative intrinsic birefringence value include aromatic vinyl polymer resins, acrylonitrile polymer resins, methyl methacrylate polymer resins, and cellulose ester polymer resins. These resins having a negative intrinsic birefringence value can be used singly or in combination of two or more. Among these, aromatic vinyl polymer resins, acrylonitrile polymer resins, and methyl methacrylate polymer resins can be preferably used, and aromatic vinyl polymer resins are particularly preferably used because they exhibit high birefringence. Can do.

  As the thermoplastic resin constituting the layer B1 and the layer B2, the total light transmittance measured by forming a test piece having a thickness of 1 mm is preferably 70% or more, more preferably 80% or more, 90% or more is particularly preferable. Examples of such a resin include a resin having an alicyclic structure, a methacrylic resin polycarbonate, a (meth) acrylic acid ester-aromatic vinyl monomer copolymer resin, and a polyethersulfone. Of these, methacrylic resin is preferred. In the present invention, the thermoplastic resin constituting the layer B1 and the thermoplastic resin constituting the layer B2 may be of the same type or different types.

  The thickness of the retardation layer is preferably 20 μm to 200 μm, more preferably 40 μm to 180 μm.

(Other components)
The optical film of the present invention can optionally further include other layers in addition to the first transparent polymer film, the alignment film, the selective reflection layer, the retardation layer, and the second transparent polymer film. Specifically, for example, an adhesive layer for adhering them can be provided between the selective reflection layer and the retardation layer and / or between the second transparent polymer film and the retardation layer. Specifically, for example, a composition having a shear storage modulus of 1 to 500 MPa at a temperature of 23 ° C. can be used as the adhesive layer.

  The said composition contains the main polymer which comprises an adhesive agent. Examples of the main polymer include acrylic polymers and acrylic copolymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, polyvinyl alcohols, ethylene / vinyl acetate copolymers, ethylene / acrylic ester copolymers, Examples include ethylene / vinyl chloride copolymer, thermoplastic elastomer, epoxy, natural rubber, and synthetic rubber. Among these, a thermoplastic elastomer, an ethylene / vinyl acetate copolymer, and an ethylene / acrylic acid ester copolymer are preferable because they are excellent in transparency, exhibit appropriate wettability and cohesion, and have excellent weather resistance. Thermoplastic elastomer is a resin having rubber elasticity at room temperature without vulcanization treatment. Specifically, styrene-butadiene block copolymer, styrene-ethylene block copolymer, styrene-butadiene- Styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylenebutylene-styrene block copolymer, styrene-ethylenepropylene-styrene block copolymer, ethylene-propylene copolymer and ethylene-propylene terpolymer , Polyethylene, polypropylene, and those having a carboxyl group or a sulfonyl group introduced thereto. The molecular weight of these main polymers is the weight average molecular weight (Mw) of polyisoprene measured by gel permeation chromatography, and is usually 10,000 to 500,000, preferably 20,000 to 400, 000.

  Depending on the type of the main polymer, other compounding agents can be blended in the composition. Examples of other compounding agents include tackifiers, crosslinking agents or curing agents, antioxidants, light diffusing agents, antifoaming agents, and stabilizers.

  The tackifier imparts adhesive force to the main polymer that is soft and has a solid surface that is easily wetted. Such tackifiers include rosin and rosin derivatives, polyterpene resins, terpene phenol resins, coumarone-indene resins, petroleum resins, hydrogenated petroleum resins and the like. Among these, petroleum resins, hydrogenated petroleum resins, and terpene phenol resins are preferable because they are excellent in transparency and compatibility with the main polymer. The compounding amount of the tackifier is preferably 2 to 50 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the main polymer. When the addition amount of the tackifier is less than 2 parts by weight, the effect of the tackifier is not expressed, and conversely, when the addition amount exceeds 50 parts by weight, the adhesive force decreases due to the decrease in the cohesive force of the adhesive. Tend to be.

  Examples of the crosslinking agent or curing agent include polyfunctional isocyanate crosslinking agents such as tolylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylolpropane tolylene diisocyanate, diphenylmethane triisocyanate; ethylene glycol glycidyl ether, polyethylene glycol di Epoxy crosslinking agents or curing agents such as glycidyl ether, diglycidyl ether, trimethylolpropane triglycidyl ether; vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3 , 4-Epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) A silane crosslinking agent or curing agent such as 3-aminopropyltrimethoxysilane; a melamine resin crosslinking agent; a metal chelate crosslinking agent; an amine crosslinking agent is used. The blending amount of the crosslinking agent or curing agent is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the main polymer. When the addition amount of the crosslinking agent or curing agent is less than 0.001 part by weight, the effect of the crosslinking agent is not exhibited, and foaming and peeling are conspicuous in a weather resistance test or the like. On the contrary, when the addition amount of the crosslinking agent or the curing agent is more than 10 parts by weight, the stress relaxation property of the adhesive is lowered, and warpage becomes conspicuous.

  Examples of the antioxidant include phenol-based antioxidants such as tetrakis (methylene-3- (3,5di-t-butyl-4-hydroxyphenyl) propionate) methane, phosphorus-based antioxidants, and thioether-based antioxidants. Is mentioned. The blending amount of the antioxidant is within a range in which the transparency and adhesive strength of the adhesive layer are not lowered.

The shear storage elastic modulus of the composition constituting the adhesive layer varies depending on the main polymer composition, the addition amount of the tackifier, the addition amount of the crosslinking agent, and the like.
Regarding the main polymer composition, in the copolymer, the shear storage elastic modulus at normal temperature tends to decrease by increasing the ratio of the monomer to be a soft segment. On the contrary, the shear storage elastic modulus at room temperature tends to increase by increasing the ratio of the monomer that becomes the hard segment. Moreover, also in the composition, when the molecular weight of the polymer is lowered, the temperature range showing the rubber-like flat region is narrowed, so that the shear storage elastic modulus at normal temperature tends to be lowered. On the contrary, by increasing the molecular weight of the polymer, the temperature range showing the rubber-like flat region is widened, and the shear storage modulus at room temperature tends to increase. Generally, the tackifier has a high softening point of 60 degrees or more and a low molecular weight of about several thousand. By adding a tackifier, the cohesive strength of the adhesive composition is reduced, and a decrease in shear storage modulus at room temperature is observed. Moreover, the cohesive force of adhesive composition rises by mixing a crosslinking agent, and the raise of the shear storage elastic modulus in room temperature is seen.

  The shear storage modulus at 23 ° C. of the composition, that is, the hot-melt adhesive is preferably adjusted to 1 to 500 MPa. When the shear storage elastic modulus at 23 ° C. is less than 1 MPa, adhesiveness is exhibited at room temperature, and a paste residue is generated on the punching blade or the tab agent during post-processing such as punching of the laminated film. Conversely, when the shear storage modulus at 23 ° C. exceeds 500 MPa, it must be heated to a high temperature, for example, exceeding 110 ° C., in order to develop the tackiness necessary for laminating the film. If the temperature exceeds 110 ° C., the heat load on the film is too large and the film may be deformed. Moreover, the adhesive force with the film of an adhesive agent also falls. The shear storage modulus at 23 ° C. of the composition is more preferably 2 to 300 MPa, and even more preferably 5 to 250 MPa.

  When the composition is used as an adhesive, the composition can be used by dissolving or dispersing in a solvent or water. As the solvent, toluene, ethyl acetate, butyl acetate, isobutyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, isobutyl alcohol, or the like can be used.

  In the optical film of the present invention, when the adhesive layer is provided, the average thickness of the adhesive layer is preferably 2 μm to 50 μm, and more preferably 5 μm to 30 μm. The average thickness is represented by the average value of the measured values at each measurement point by measuring the thickness of the adhesive layer at equal intervals in the width direction.

(Production method)
The optical film of the present invention can be preferably produced by the method for producing an optical film of the present invention described below. In the method for producing an optical film of the present invention, the first laminated film including the first transparent polymer film, the alignment film, and the selective reflection layer, the retardation layer, and the second transparent polymer. A 2nd laminated film provided with a film is stuck by roll-to-roll.

  The first laminated film is prepared by forming the alignment film on the first transparent polymer film by the method described above, and further providing the selective reflection layer after rubbing treatment as necessary. can do. The second laminated film can be prepared by pasting the second transparent polymer film and the retardation layer through an adhesive.

  The first laminated film and the second laminated film are attached in a roll-to-roll manner. Here, roll-to-roll means that each laminated film is supplied to a production line, and an optical film is obtained by performing a sticking process in the production line. Further, the obtained optical film is wound in the form of a roll downstream. To take. Here, supply of each laminated | multilayer film can be performed by paying out what was prepared beforehand and made into the state of the roll. Or you may supply the laminated | multilayer film continuously prepared with another manufacturing line to the line of this sticking process as it is.

  An example of the pasting process will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram showing a manufacturing process of an optical film, and FIG. 2 is a schematic diagram showing an enlarged region R of FIG.

  In FIG. 1 and FIG. 2, a first laminated film 130 including a first transparent polymer film 131, an alignment film 132, a selective reflection layer 133 and an adhesive layer 124, a second transparent polymer film 121, and a phase difference The second laminated film 120 to which the layer 123 is bonded via the adhesive layer 122 is supplied to the apparatus, and is pressed by the nip rolls 111 and 112 to be processed into a seven-layer brightness enhancement film laminate 140. The laminate 140 is pressed by the pressure roll 113 and is wound up as a roll while receiving torque due to the rotation of the winding roll 101. The winding tension (N / m) at this time can be 30 to 200. And in such a manufacturing process, the length of the width direction of the laminated body 140 can be 500 mm or more, Preferably it can be 1000 mm or more. By performing such roll-to-roll application, the optical film of the present invention can be efficiently produced.

(Liquid crystal display device)
The liquid crystal display device of the present invention includes the optical film of the present invention. The specific mode in which the liquid crystal display device of the present invention includes an optical film is not particularly limited. For example, the light supplied from the backlight to the liquid crystal cell by being provided as a brightness enhancement film between the backlight and the liquid crystal cell. The luminance of the desired polarized light can be improved, and as a result, the luminance of the liquid crystal display device can be improved. The optical film can be fixed to a substrate such as a liquid crystal cell substrate with a member such as a fixing pin and / or a frame. Even if the optical film is provided on the liquid crystal display device in such an easily removable manner, the optical film of the present invention is excellent in durability, so that wrinkles and curls are hardly generated, and when the liquid crystal display device is discarded. The optical film can be easily removed from the cell substrate.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example. In the following examples, “parts” and “%” indicate parts by weight and% by weight unless otherwise specified.

<Production Example 1> Production of transparent polymer film: Part 1
Pellets of thermoplastic norbornene resin (ZEONOR 1420, manufactured by Nippon Zeon Co., Ltd .; glass transition temperature Tg 136 ° C.) were dried at 100 ° C. for 4 hours using a hot air dryer in which air was circulated. This pellet has a 50 mm single screw extruder with a leaf disk polymer filter (filtration accuracy 30 μm) and a lip that is polished with a # 1000 diamond grindstone with a lip material of tungsten carbide. Extrusion was performed at 260 ° C. using a 650 mm wide T-shaped die plated with chrome plating with roughness Ra = 0.05 μm, and the extruded sheet-like thermoplastic norbornene resin was cooled to the first cooling drum (diameter 250 mm, temperature: 135). C, circumferential speed R ₁ : 10.05 m / min), then second cooling drum (diameter 250 mm, temperature 125 ° C., circumferential speed R ₂ : 10.05 m / min), then third cooling drum (diameter 250 mm) , Temperature 100 ° C., peripheral speed R ₃ : 9.98 m / min. A long transparent polymer film (1) having a thickness of 0 mm, a thickness of 100 μm, and a length of 500 m was obtained. Re of this transparent polymer film (1) was 1 nm.

<Production Examples 2 to 5> Production of transparent polymer film: 2 to 5
Four types with the same width and length and different thickness as the transparent polymer film (1) except that the T-type die different from Production Example 1 was used and the film take-up speed was adjusted. Transparent polymer films (2) to (5) were obtained. Their thickness was 80 μm, 90 μm, 188 μm and 200 μm, respectively. Re of these transparent polymer films (2) to (5) was 1 nm.

<Production Example 6> Preparation of retardation film Rubber particles were produced by the method described in Example 3 of Japanese Patent Publication No. 55-27576. The rubber particles have a spherical three-layer structure, the core layer is a crosslinked polymer consisting of methyl methacrylate and a small amount of allyl methacrylate, and the intermediate layer is composed of butyl acrylate, styrene and a small amount of allyl methacrylate. It is a crosslinked polymer, and the shell layer is a polymer composed of methyl methacrylate and a small amount of ethyl acrylate. The number average particle diameter of the rubber particles was 0.19 μm. 70 parts of alkyl methacrylate polymer resin (methyl methacrylate / methyl acrylate (mass ratio) = 97.8 / 2.2 copolymer resin, glass transition temperature 105 ° C.) and 30 parts of the rubber particles By kneading, a methacrylic acid alkyl ester polymer resin composition (hereinafter referred to as PMMA; containing 30% rubber particles) was obtained.
The PMMA, styrene polymer resin (Dylark D332, manufactured by Nova Chemical Japan Co., Ltd., styrene-maleic anhydride copolymer, glass transition temperature 125 ° C., hereinafter referred to as PST), and the PMMA are respectively used in an extruder. It was melted and fed to a die for coextrusion. The supplied molten resin passes through the die slip and is formed into a multi-layer film having a three-layer structure of PMMA / PST / PMMA, and then the slow axis is tilted 45 degrees with respect to the MD direction by a tenter stretching machine. As shown, the film was diagonally stretched at a stretching temperature of 134 ° C. and a stretching ratio of 1.8 times, and the width was 1000 mm, the thickness was 90 μm, the average thickness of the PMMA layer was 34 μm, the average thickness of the PST layer was 22 μm, and the average thickness of the PMMA layer was 34 μm. The retardation film was taken up with a take-up roll. The slow axis was inclined 45 degrees in the MD direction. The retardation Re in the in-plane direction at the wavelength of 550 nm of the retardation film was 140 nm, and the retardation Rth in the thickness direction was −85 nm.

<Example 1>
(1-1) Formation of Alignment Film The transparent polymer film (1) obtained in Production Example 1 was used as the first transparent polymer film. On this one surface, a 5% aqueous solution of polyvinyl alcohol was continuously applied on the production line and dried to obtain a transparent polymer film having an alignment film having a dry film pressure of 0.3 μm.

(1-2) Formation of selective reflection layer: Preparation of first laminated film (L-1A) Rod-shaped liquid crystal compound having Δn of 0.18 (asymmetric structure, 2 reactive groups in one molecule) 33.0 parts, A1 compound (Compound represented by the following compound A1; melting point 66 ° C.) 3.5 parts, chiral agent (LC756; manufactured by BASF) 2.3 parts, polymerization initiator (Irgacure 907; manufactured by Ciba Specialty Chemicals) 1.2 parts A cholesteric liquid crystal composition having a solid content of about 40% was prepared by blending 0.04 part of a surfactant (fluorinated surfactant KH40; manufactured by Seimi Chemical Co., Ltd.) and 60 parts of 2-butanone.

This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared in (1-1) using a # 10 wire bar. The coating film is subjected to orientation treatment at 100 ° C. for 5 minutes and then irradiated with ultraviolet rays of 500 mJ / cm ² to form a selective reflection layer having a dry film thickness of 5 μm, wound as a roll, a transparent polymer film, an orientation film and a selective reflection layer. The roll of the 1st laminated film (L-1A) which has was obtained.

(1-3) Formation of second laminated film (L-2A) The transparent polymer film (1) obtained in Production Example 1 was used as the second transparent polymer film. On one side, an adhesive (ethylene-vinyl acetate copolymer emulsion (non-volatile content 40% by weight, vinyl acetate content 40% by weight) 40 parts by weight, petroleum resin emulsion (non-volatile content 40% by weight, resin softening point) 85 ° C) 35 parts by weight and paraffin wax emulsion (non-volatile content 40% by weight, resin softening point 64 ° C) 10 parts by weight, an adhesive formed by a composition having a shear storage modulus of 10 MPa at 23 ° C ) Is applied to a thickness of 20 μm, and the retardation film (6) obtained in Production Example 5 is pasted thereon, wound up as a roll, transparent polymer film (1), adhesive layer and retardation film A roll of the second laminated film (L-2A) comprising (6) was obtained.

(1-4) Production and evaluation of optical film The film is fed out from the roll of the first laminated film (L-1A), and the same adhesion as that used in (1-3) above is applied to the surface of the selective reflection layer side. The coating agent was applied to a thickness of 20 μm, and the film fed from the roll of the second laminated film (L-2A) was stuck thereon so that the retardation film side faced the selective reflection layer side, and the laminate As a roll, an optical film roll was obtained.
This optical film is cut into a size of 15 cm × 21 cm, placed under the following evaluation conditions 1 and 2, and then placed on a flat glass. mm). The results are shown in Table 1.
Evaluation condition 1: temperature 85 ° C., relative humidity 5%, 1000 hours Evaluation condition 2: temperature 65 ° C., relative humidity 95%, 1000 hours

<Example 2>
Except having changed the following matter, it operated similarly to Example 1, the optical film was obtained, and the curl amount was measured. The results are shown in Table 1.
In the step (1-1), a transparent polymer film (2) (thickness 80 μm) is used instead of the transparent polymer film (1).
In the step (1-3), a transparent polymer film (3) (thickness 90 μm) is used instead of the transparent polymer film (1).

<Example 3>
Except having changed the following matter, it operated similarly to Example 1, the optical film was obtained, and the curl amount was measured. The results are shown in Table 1.
In the step (1-1), a transparent polymer film (5) (thickness: 200 μm) is used instead of the transparent polymer film (1).
In the step (1-3), a transparent polymer film (4) (thickness: 188 μm) is used instead of the transparent polymer film (1).

<Comparative Example 1>
Except having changed the following matter, it operated similarly to Example 1, the optical film was obtained, and the curl amount was measured. The results are shown in Table 1.
In the step (1-3), a transparent polymer film (4) (thickness: 188 μm) is used instead of the transparent polymer film (1).

<Comparative example 2>
Except having changed the following matter, it operated similarly to Example 1, the optical film was obtained, and the curl amount was measured. The results are shown in Table 1.
In the step (1-1), a transparent polymer film (2) (thickness 80 μm) is used instead of the transparent polymer film (1).

<Comparative Example 3>
Except having changed the following matter, it operated similarly to Example 1, the optical film was obtained, and the curl amount was measured. The results are shown in Table 1.
In the step (1-1), a transparent polymer film (5) (thickness: 200 μm) is used instead of the transparent polymer film (1).
In the step (1-3), a glass plate (thickness 700 μm) is used instead of the transparent polymer film (1).

  In the table, “ZNR” represents a thermoplastic norbornene resin: ZEONOR1420 (trade name, manufactured by Nippon Zeon Co., Ltd.).

  As is clear from the results in Table 1, the optical film of the present invention has low durability and high durability against curling under evaluation conditions such as high temperature and high humidity, whereas the optical films of comparative examples all have durability. Was inferior.

<Example 4> Production of liquid crystal display device A commercially available liquid crystal display device (manufactured by Sharp, AQUAS, LC-37BE1W) was disassembled, and a brightness enhancement film was taken out.
The same operation as in Example 1 was performed except that the cut size was the same as that of the brightness enhancement film, and the same optical characteristics as the optical film obtained in Example 1 were obtained. An optical film was prepared. It replaced with the brightness enhancement film which took out this optical film, it installed in the liquid crystal display device, it assembled again, and the liquid crystal display device which has an optical film was obtained. In the obtained liquid crystal display device, good white display and black display were confirmed, and it was confirmed that the display was performed with the same luminance as before the decomposition.

It is the schematic which shows an example of the manufacturing process of the optical film of this invention. It is the schematic which expands and shows the area | region R in the manufacturing process shown in FIG.

Explanation of symbols

101 Winding Rolls 111, 112 Nip Roll 113 Pressure Roll 120 Second Laminated Film 121 Second Transparent Polymer Film 122 Adhesive Layer 123 Retardation Layer 124 Adhesive Layer 130 First Laminated Film 131 First Transparent Polymer Film 132 Alignment film 133 Selective reflection layer 140 Optical film

Claims (4)

  An optical film comprising a first transparent polymer film, an alignment film, a selective reflection layer, a retardation layer, and a second transparent polymer film in this order, wherein the first transparent polymer film and the second transparent polymer film The transparent polymer film is made of the same material, and the thickness A of the first transparent polymer film and the thickness B of the second transparent polymer film are (0.8A) ≦ B ≦ (1.2A) An optical film having the following relationship:   2. The optical device according to claim 1, wherein each of the first transparent polymer film and the second transparent polymer film is a resin film having an alicyclic structure having a thickness of 50 to 250 μm. the film.   It is a manufacturing method of the optical film of Claim 1 or 2, Comprising: A 1st laminated | multilayer film provided with a said 1st transparent polymer film, the said alignment film, and the said selective reflection layer, The said phase difference layer, and A method for producing an optical film, wherein the second laminated film including the second transparent polymer film is attached by roll-to-roll.   A liquid crystal display device comprising the optical film according to claim 1.

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