JPWO2016006388A1 - Optical film - Google Patents

Abstract

The present invention provides an optical film that can further reduce the occurrence of wrinkles and undulations when being attached to glass, particularly when being attached to glass having a small curvature radius. The present invention is an optical film having a dielectric multilayer film in which a high refractive index layer containing a first polymer and a low refractive index layer containing a second polymer are alternately laminated on a resin substrate. When the optical film is held at 130 ° C. for 30 minutes, the thermal shrinkage rate in any one direction is Ta (unit:%), and the thermal shrinkage rate in the direction orthogonal to the arbitrary one direction is Tb (unit: %), Formula (1) 2.0 <Ta <4.5, formula (2) 1.6 <Tb <3.5, formula (3) 0.2 ≦ | Ta−Tb | ≦ 1. It is an optical film satisfying all zero.

Description

  The present invention relates to an optical film.

  In recent years, heat shielding films and laminated glass with high heat insulation or heat ray blocking properties have been put on the market in order to block the heat felt by human skin due to the influence of the sun entering from the car window, suppress the operation of the air conditioner in the car and save energy. It is in circulation. In general, laminated glass has an optical film disposed between a pair of plate glasses, and the optical film blocks transmission of solar rays to heat rays (infrared rays), thereby reducing indoor temperature rise and cooling load.

  The laminated glass is used for a windshield of an automobile. Recent windshields have a three-dimensional curved surface, and the radius of curvature has been reduced from the viewpoint of design. Along with that, the optical film cannot follow the curved surface, and defects such as wrinkles and undulation may occur during the production of laminated glass or after pasting to automotive glass, etc., and technology to reduce such wrinkles and undulation Is required.

  Various proposals have been made for such demands. For example, Japanese Patent Application Laid-Open No. 2009-208980 discloses that the heat shrinkage in the longitudinal direction of the film after heat treatment at 150 ° C. for 30 minutes is 0.6% or more and 1.2% or less, and the heat shrinkage in the width direction is 0. A polyester film for laminated glass interlayer film of 15% or more and 1.0% or less is disclosed.

  Japanese Patent Application Laid-Open No. 2010-180089 (corresponding to US Patent Application Publication No. 2011/287229) discloses a plastic film having an infrared reflection film formed by alternately laminating resin films having different refractive indexes. A plastic film-inserted laminated glass having a specific range of heat shrinkage, elastic modulus, and elongation is disclosed.

  Further, JP2013-086987A discloses laminated glass in which a resin film is sandwiched between a first glass substrate and a second glass substrate via an adhesive layer, and after being held at 150 ° C. for 30 minutes. The heat shrinkage rate in the direction in which the heat shrinkage rate is maximum is more than 1% and less than 2%, and the heat shrinkage rate after holding at 150 ° C. for 30 minutes in the direction orthogonal to the direction is more than 1% and less than 2% A laminated glass is disclosed.

  In addition, JP-A-2011-195417 has a heat ray reflective film in which high refractive index dielectric layers and low refractive index dielectric layers are alternately laminated on one main surface of a transparent resin film, and the other A laminated glass provided with a heat ray reflective film having a hard coat layer containing a near-infrared absorbing dye on the main surface of the film is disclosed, and according to the heat ray shielding film, it is described that the occurrence of waviness can be suppressed. ing.

  However, JP 2009-208980 A, JP 2010-180089 A (corresponding to US Patent Application Publication No. 2011/287229), JP 2013-086987 A, and JP 2011-195417 A. In the technique described in 1), when applied to glass having a small radius of curvature such as three-dimensional curved glass, there is a problem that wrinkles and undulations of the film used are insufficiently reduced.

  The present invention has been made in view of the above problems, and its purpose is to provide an optical film that can further reduce the occurrence of wrinkles and undulations when affixed to glass, particularly when affixed to glass having a small radius of curvature. Is to provide.

  The inventor has conducted extensive research. As a result, an optical film having a dielectric multilayer film in which a high refractive index layer containing a first polymer and a low refractive index layer containing a second polymer are alternately laminated on a resin substrate. We found that the above problems can be solved by setting the difference between the heat shrinkage rate in the direction, the heat shrinkage rate in the direction orthogonal to the one arbitrary direction, and the heat shrinkage rate in the two directions to a specific range, and completed the present invention. I came to let you.

  The present invention is an optical film having a dielectric multilayer film in which a high refractive index layer containing a first polymer and a low refractive index layer containing a second polymer are alternately laminated on a resin substrate. When the optical film is held at 130 ° C. for 30 minutes, the thermal shrinkage rate in any one direction is Ta (unit:%), and the thermal shrinkage rate in the direction orthogonal to the arbitrary one direction is Tb (unit: %), The optical film satisfies all of the following formulas (1) to (3).

  Wrinkles are a phenomenon that occurs due to the excessive shrinkage of the film due to excessive heat shrinkage during the pasting process to laminated glass and automotive glass. Waviness is a phenomenon in which minute deformation occurs during processing of the film, and the film undulates in the film thickness direction at a large wavelength. In the optical film of the present invention, the heat shrinkage rate Ta in one arbitrary direction and the heat shrinkage rate Tb in the direction orthogonal to the one arbitrary direction are large even under a relatively low temperature condition of 130 ° C., and Ta and Tb The absolute value of the difference is large. As a result, wrinkles and undulations are less likely to occur during the manufacture of laminated glass having a large curvature (that is, having a small radius of curvature) and post-lamination processing on an automotive glass having a large curvature. In addition, in the production of laminated glass using resin glass having a large curvature and low heat resistance and post-bonding processing to resin glass, the optical film of the present invention is used to remove wrinkles and undulations. Since thermoforming is completed in a short time, it is possible to efficiently reduce wrinkles and undulations while suppressing deformation of the resin glass itself.

  Hereinafter, the components of the optical film of the present invention, the form for carrying out the present invention, and the like will be described in detail.

[Optical film]
The total film thickness of the optical film of the present invention is preferably 10 μm to 300 μm, more preferably 20 μm to 250 μm. If it is this range, it will become an optical film excellent in transparency in long-term use. The use of the optical film of the present invention can be controlled by adjusting the number of laminated dielectric multilayer films or the optical film thickness, refractive index, or component of each layer. For example, the optical film of the present invention includes a metallic glossy film, a visible light shielding film that shields light having a wavelength of 380 to 780 nm, an ultraviolet shielding film that shields light having a wavelength of less than 380 nm, and an infrared that shields light having a wavelength of more than 780 nm. It can be suitably used as a shielding film or an ultraviolet-infrared shielding film that shields both ultraviolet light and infrared light. In general, when used as an ultraviolet shielding film or an infrared shielding film, it is preferable not to shield light (visible light) having a wavelength of 380 to 780 nm.

  As an optical characteristic of the optical film of the present invention, the visible light transmittance measured by JIS R3106: 1998 is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more. Moreover, it is preferable to have the area | region which has a reflectance exceeding 50% in the area | region of wavelength 900nm-1400nm.

  In the optical film of the present invention, when held at 130 ° C. for 30 minutes, the thermal shrinkage rate in any one direction is Ta (unit:%), and the thermal shrinkage rate in the direction orthogonal to the arbitrary one direction is Tb. When (unit:%), all of the following formulas (1) to (3) are satisfied.

  When the thermal shrinkage rate Ta in any one direction is 2.0% or less, wrinkles and undulations are not reduced. Further, when Ta is 4.5% or more, the shrinkage is too large, and when it is bonded to glass, a manufacturing defect such as a gap at the end portion occurs. The Ta is preferably 2.2 to 3.3%, more preferably 2.5 to 3.0%.

  Further, when the thermal shrinkage rate Tb in the direction orthogonal to the arbitrary one direction is 1.6% or less, wrinkles and undulations are not reduced. Further, when Tb is 3.5% or more, the shrinkage is too large, and when it is bonded to glass, a manufacturing defect such as a gap at the end portion occurs. The Tb is preferably 1.2 to 3.1%, more preferably 2.0 to 2.5%.

  Furthermore, when the absolute value (| Ta−Tb |) of the difference in thermal contraction rate is less than 0.2%, wrinkles and undulations are not reduced. On the other hand, if | Ta−Tb | exceeds 1.0%, the anisotropy of thermal shrinkage is too large, and conversely wrinkles and undulations may occur. | Ta-Tb | is preferably 0.5 to 1.0%.

  The thermal shrinkage rate of the optical film can be measured by the following method. That is, after storing the optical film at a temperature of 23 ° C. and a relative humidity of 55% RH for 24 hours, two marks are made at intervals of 100 mm in the width direction, and the distance A1 between the two marks is measured with no load. Measure using a microscope. Subsequently, the optical film is suspended in an oven at 130 ° C. and left for 30 minutes. After 30 minutes, the optical film is removed from the oven and stored again for 24 hours in an environment at a temperature of 23 ° C. and a relative humidity of 55% RH. Next, the distance A2 between the two marks on the unloaded optical film is measured using an optical microscope. From the measured distances A1 and A2, the thermal shrinkage rate of the optical film is calculated by the following formula. This measurement is performed in two directions: an arbitrary direction of the optical film (for example, MD) and a direction orthogonal to the arbitrary one direction (for example, TD). At this time, if the heat shrinkage rate is positive, it indicates shrinkage, and negative indicates elongation. Furthermore, the absolute value of the difference between the heat shrinkage rate Ta in one arbitrary direction of the calculated optical film and the heat shrinkage rate Tb in the direction orthogonal to the one arbitrary direction is calculated.

  The thermal shrinkage rate of the optical film of the present invention can be controlled by a method of controlling the thermal shrinkage rate in any one direction of the resin base material and the thermal shrinkage rate in the direction orthogonal to the one arbitrary direction. The heat shrinkage rate of the resin base material can be controlled by controlling the stretching ratio in two directions, the heat setting temperature, the relaxation rate in two directions, and the like when manufacturing the base material as described below.

[Resin substrate]
The resin substrate according to the present invention is not particularly limited as long as it is formed of an organic material capable of holding a dielectric multilayer film. Specific examples include polyolefin films (polyethylene, polypropylene, etc.), polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, cellulose triacetate, etc., preferably polyester films. Although it does not specifically limit as a polyester film, It is preferable that it is polyester which has the film formation property which has a dicarboxylic acid component and a diol component as main structural components. The main constituent dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethanedicarboxylic acid, Examples thereof include cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, and phenylindane dicarboxylic acid. Examples of the diol component include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis ( 4-Hydroxyphenyl) sulfone, bisphenol fluorene hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like. Among the polyesters having these as main constituent components, from the viewpoint of transparency, mechanical strength, dimensional stability, etc., dicarboxylic acid components such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diol components such as ethylene glycol and 1 Polyester having 1,4-cyclohexanedimethanol as the main constituent is preferred. Of these, polyesters mainly composed of polyethylene terephthalate and polyethylene naphthalate, copolymer polyesters composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and mixtures of two or more of these polyesters are mainly used. Polyester as a constituent component is preferable.

  The thickness of the resin base material used in the present invention is preferably 10 to 300 μm, more preferably 20 to 250 μm. In addition, the resin base material may be a laminate of two or more, and in that case, the type of resin may be the same or different.

  The resin base material can be manufactured by a conventionally known general method. For example, an unstretched resin base material that is substantially amorphous and not oriented can be produced by melting a resin as a material with an extruder or the like, extruding it with an annular die or a T-die, and quenching. Further, the unstretched resin base material is uniaxially stretched, tenter-type sequential biaxial stretch, tenter-type simultaneous biaxial stretch, tubular-type simultaneous biaxial stretch, and other known methods such as base material flow (longitudinal and longitudinal) directions. Alternatively, a stretched resin substrate can be produced by stretching in a direction perpendicular to the flow direction of the substrate (lateral, lateral). In order to obtain the difference between the heat shrinkage rate and the heat shrinkage rate specified in the present invention, it is preferable to use a resin base material stretched by the following stretching method. Hereinafter, an example of the manufacturing method of the stretched polyester film which is a preferable resin base material is demonstrated below.

  After drying the polyester chip, it is melt-extruded into a film using an extruder and cooled and solidified with a casting drum to produce an unstretched film. This unstretched film is once or twice or more in the machine direction (longitudinal direction, MD (Machine Direction)) in a temperature range of Tg to (Tg + 60) ° C., so that the total magnification is preferably 3 to 6 times. Stretch longitudinally, and then transverse to the transverse direction (width direction, TD: TD: Transverse Direction) at a temperature range of Tg to (Tg + 70) ° C. so that the magnification is preferably 3 to 5 times. A biaxially stretched film is obtained by stretching. Such bi-directional stretching may be performed sequentially in the vertical and horizontal directions, or may be performed simultaneously. Here, the draw ratio in the longitudinal direction is more preferably 3 to 5 times, and still more preferably 3 to 4 times. Moreover, the draw ratio of a horizontal direction becomes like this. More preferably, it is 3-4.5 times, More preferably, it is 3-4 times.

  Thereafter, heat treatment is further performed at 180 to 230 ° C. for 1 to 60 seconds as necessary. By this heat treatment, crystallites can be generated and the mechanical properties and durability can be improved. Furthermore, it is preferable to perform relaxation heat treatment at a temperature lower by 20 to 50 ° C. than the heat treatment temperature while shrinking by 1 to 10% in the lateral direction. The relaxation heat treatment is a process for applying heat to the film to relieve stress and shrinking the film. The relaxation heat treatment can be performed by a known method, for example, a method of performing relaxation heat treatment by narrowing the clip interval in the width direction after completion of stretching in the film forming process. The above Tg represents the glass transition temperature of polyester.

[Dielectric multilayer film]
The dielectric multilayer film according to the present invention is formed on a resin base material, and is formed by alternately laminating a high refractive index layer containing a first polymer and a low refractive index layer containing a second polymer. The preferred dielectric multilayer film of the present invention can also be said to be an optical reflection layer utilizing the refractive index difference between the refractive index layers. The dielectric multilayer film may be formed on one surface of the resin base material, or may be formed on both surfaces of the resin base material.

  In the present specification, a refractive index layer having a higher refractive index than the other is referred to as a high refractive index layer, and a refractive index layer having a lower refractive index than the other is referred to as a low refractive index layer. In this specification, the terms “high refractive index layer” and “low refractive index layer” refer to a refractive index layer having a higher refractive index when comparing the refractive index difference between two adjacent layers. It means that the lower refractive index layer is a low refractive index layer. Therefore, the terms “high refractive index layer” and “low refractive index layer” mean that when each refractive index layer constituting the dielectric multilayer film is focused on two adjacent refractive index layers, All forms other than those having the same refractive index are included.

  The dielectric multilayer film includes a high refractive index layer and a low refractive index layer. The high refractive index layer and the low refractive index layer are considered as follows.

  For example, a component constituting a high refractive index layer (hereinafter also referred to as a high refractive index layer component) and a component constituting a low refractive index layer (hereinafter also referred to as a low refractive index layer component) are mixed at the interface between the two layers. In some cases, a layer (mixed layer) including a high refractive index layer component and a low refractive index layer component may be formed. In this case, in the mixed layer, a set of portions where the high refractive index layer component is 50% by mass or more is defined as a high refractive index layer, and a set of portions where the low refractive index layer component exceeds 50% by mass is defined as a low refractive index layer. . In a dielectric multilayer film that does not contain a metal oxide in the low refractive index layer component or the high refractive index layer component and is formed only from a polymer, the polymer concentration profile indicates, for example, carbon in the film thickness direction. By confirming the existence of the mixed region by measuring the concentration, and further measuring the composition by EDX, each layer etched by sputtering can be regarded as a high refractive index layer or a low refractive index layer. it can.

  When the low refractive index layer contains, for example, a metal oxide as a low refractive index layer component, and the high refractive index layer contains a metal oxide as a high refractive index layer component, the film in these dielectric multilayer films The metal oxide concentration profile in the thickness direction is measured, and can be regarded as a high refractive index layer or a low refractive index layer depending on its composition. The metal oxide concentration profile of the dielectric multilayer film is sputtered at a rate of 0.5 nm / min using the XPS surface analyzer, etching from the surface to the depth direction using the sputtering method, and setting the outermost surface to 0 nm. It can be observed by measuring the atomic composition ratio.

  There is no particular limitation on the XPS surface analyzer, and any model can be used. For example, ESCALAB-200R manufactured by VG Scientific, Inc. can be used. Mg can be used for the X-ray anode, and measurement can be performed at an output of 600 W (acceleration voltage: 15 kV, emission current: 40 mA).

  In general, in a dielectric multilayer film, it is preferable to design a large difference in refractive index between a low refractive index layer and a high refractive index layer from the viewpoint that the optical reflectance can be increased with a small number of layers. In the dielectric multilayer film, the refractive index difference between the adjacent low refractive index layer and high refractive index layer is preferably 0.1 or more, more preferably 0.3 or more, and further preferably 0.35 or more. And particularly preferably more than 0.4. When the optical film has a plurality of low refractive index layers and high refractive index layers, it is preferable that the refractive index differences of all the high refractive index layers and the low refractive index layers are within the above-mentioned preferable range. However, the outermost layer of the dielectric multilayer film may have a configuration outside the above preferred range. The preferable refractive index of the low refractive index layer is 1.10 to 1.60, more preferably 1.30 to 1.50. The preferable refractive index of the high refractive index layer is 1.55 to 2.50, more preferably 1.60 to 2.20.

  The reflectance in the specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of stacked layers. The larger the difference in refractive index, the same reflectance can be obtained with a smaller number of layers. The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain an infrared reflectance of 90% or more, if the difference in refractive index is less than 0.1, it is necessary to laminate 200 layers or more, which not only decreases productivity but also scattering at the interface of the layers. Becomes larger, the transparency is lowered, and it becomes very difficult to manufacture without failure. From the standpoint of improving reflectivity and reducing the number of layers, there is no upper limit to the difference in refractive index, but practically about 1.4 is the limit.

  From the above viewpoint, the upper limit of the number of laminated dielectric multilayer films is preferably 100 layers or less, more preferably 50 layers or less, and even more preferably 34 layers or less. On the other hand, the lower limit of the total number of layers of the dielectric multilayer film is preferably 6 layers or more, more preferably 8 layers or more, and even more preferably 10 layers or more. Within this range, the surface rigidity of the entire optical film becomes an appropriate value, wrinkles and waviness can be suppressed, and handling properties such as cutting and winding properties when processing an optical film are further improved. To do.

  The dielectric multilayer film only needs to have a structure in which at least one high refractive index layer and low refractive index layer are laminated. For example, both of the layers arranged on the outermost side of the dielectric multilayer film are either high refractive index layers or A laminated structure that becomes a low refractive index layer may be used. The optical film of the present invention preferably has a layer structure in which both outermost layers in the dielectric multilayer film are low refractive index layers.

  The thickness per layer of the low refractive index layer is preferably 20 to 800 nm, and more preferably 50 to 350 nm. On the other hand, the thickness per layer of the high refractive index layer is preferably 20 to 800 nm, and more preferably 50 to 350 nm.

(First and second polymers)
In the dielectric multilayer film according to the present invention, the high refractive index layer includes the first polymer, and the low refractive index layer includes the second polymer. The first polymer and the second polymer may be the same type or different types. In addition, the first polymer and the second polymer may be used alone or in combination of two or more.

  There is no restriction | limiting in particular in the 1st and 2nd polymer, If it is a polymer which can form a dielectric multilayer film, it will not restrict | limit in particular.

  For example, the polymer described in JP-T-2002-509279 can be used as the polymer. Specific examples include, for example, polyethylene naphthalate (PEN) and isomers thereof (for example, 2,6-, 1,4-, 1,5-, 2,7- and 2,3-PEN), polyalkylene terephthalate. (Eg, polyethylene terephthalate (PET), polybutylene terephthalate, and poly-1,4-cyclohexanedimethylene terephthalate), polyimide (eg, polyacrylimide), polyetherimide, atactic polystyrene, polycarbonate, polymethacrylate (eg, Polyisobutyl methacrylate, polypropyl methacrylate, polyethyl methacrylate, and polymethyl methacrylate (PMMA)), polyacrylates (eg, polybutyl acrylate, and polymethyl acrylate), cellulose Derivatives (eg, ethylcellulose, acetylcellulose, cellulose propionate, acetylcellulose butyrate, and cellulose nitrate), polyalkylene polymers (eg, polyethylene, polypropylene, polybutylene, polyisobutylene, and poly (4-methyl) pentene), fluorine Chlorinated polymers (eg, perfluoroalkoxy resins, polytetrafluoroethylene, fluorinated ethylene propylene copolymers, polyvinylidene fluoride, and polychlorotrifluoroethylene), chlorinated polymers (eg, polyvinylidene chloride and polyvinyl chloride), polysulfones, Polyether sulfone, polyacrylonitrile, polyamide, silicone resin, epoxy resin, polyvinyl acetate, polyether amide, ionomer resin Elastomers (e.g., polybutadiene, polyisoprene and neoprene), and polyurethanes. Copolymers such as copolymers of PEN [e.g. (a) terephthalic acid or ester thereof, (b) isophthalic acid or ester thereof, (c) phthalic acid or ester thereof, (d) alkane glycol, (e) cycloalkane glycol ( For example, cyclohexanedimethanol diol), (f) alkanedicarboxylic acid, and / or (g) cycloalkanedicarboxylic acid (eg, cyclohexanedicarboxylic acid) and 2,6-, 1,4-, 1,5-, 2, 7- and / or copolymers with 2,3-naphthalenedicarboxylic acid or esters thereof], copolymers of polyalkylene terephthalates [eg (a) naphthalenedicarboxylic acid or esters thereof, (b) isophthalic acid or esters thereof, ( c) phthalic acid or The ester, (d) alkane glycol, (e) cycloalkane glycol (eg, cyclohexanedimethanol diol), (f) alkane dicarboxylic acid, and / or (g) cycloalkane dicarboxylic acid (eg, cyclohexanedicarboxylic acid); Also suitable are copolymers with terephthalic acid or esters thereof, as well as styrene copolymers (eg styrene-butadiene copolymers and styrene-acrylonitrile copolymers), 4,4-bisbenzoic acid and ethylene glycol. In addition, each layer may each include a blend of two or more of the above polymers or copolymers (eg, a blend of syndiotactic polystyrene (SPS) and atactic polystyrene).

  A dielectric multilayer film can be formed by melt extrusion and stretching of the polymer as described in US Pat. No. 6,049,419. A dielectric multilayer film can also be formed by applying a coating solution containing the above polymer by a roll coating method, a doctor knife method, a die coating method, a bar coating method, a dipping method, a spray coating method, etc., and drying to form a film. can do. Examples of the solvent used in the coating solution containing the polymer include acetone, acetonitrile, benzonitrile, N, N-dimethylacetamide, dimethyl sulfoxide, diethyl ether, ethylene glycol monoethyl ether acetate, xylene, isobutyl acetate, isopropyl acetate, acetic acid. Isoamyl, ethyl acetate, butyl acetate, propyl acetate, pentyl acetate, methyl acetate, 2-methoxyethyl acetate, hexamethylphosphate triamide, tris (dimethylamino) phosphine, cyclohexanone, 1,4-dioxane, tetrahydrofuran, toluene, hexane, Pentane, cyclohexane, cyclopentane, heptane, benzene, methyl isobutyl ketone, tert-butyl methyl ether, methyl ethyl ketone, methyl cyclohexanone Methyl butyl ketone, diethyl ketone, and the like.

  In the present invention, preferred combinations of the polymer that forms the high refractive index layer and the low refractive index layer when the above polymer is used include PEN / PMMA, PET / PMMA, PEN / polyvinylidene fluoride, PEN / PET, and the like. It is done.

  In addition, it is also preferable to use a water-soluble polymer as the first and second polymers. The water-soluble polymer is preferable because it does not use an organic solvent, has a low environmental load, and has high flexibility, so that the durability of the film during bending is improved. Examples of the water-soluble polymer include polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic ester copolymer, or acrylic. Acrylic resin such as acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic Styrene acrylic acid resin such as acid copolymer or styrene-α-methylstyrene-acrylic acid-acrylic ester copolymer, styrene-sodium styrenesulfonate copolymer, styrene-2-hydroxyethyl acrylate copolymer, Styrene-2 -Hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate -A vinyl acetate copolymer such as a maleic acid ester copolymer, a vinyl acetate-crotonic acid copolymer, or a vinyl acetate-acrylic acid copolymer. Further, gelatins described in paragraphs “0033” to “0039” of JP2013-007817A, celluloses such as methylcellulose, and thickening polysaccharides such as tamarind seed gum are also preferably used. Furthermore, inorganic polymers such as zirconyl nitrate and polyaluminum chloride can be used.

  Among these, preferred examples include polyvinyl alcohol, polyvinylpyrrolidones and copolymers containing the same, tamarind seed gum, and polyaluminum chloride from the viewpoint of handling during production, film flexibility, and the like. These water-soluble polymers may be used alone or in combination of two or more.

  As the polyvinyl alcohol used in the present invention, a synthetic product or a commercially available product may be used. Examples of commercially available products used as polyvinyl alcohol include, for example, PVA-102, PVA-103, PVA-105, PVA-110, PVA-117, PVA-120, PVA-124, PVA-203, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-235 (above, manufactured by Kuraray Co., Ltd.), JC-25, JC-33, JF-03, JF-04, JF-05, JP- 03, JP-04JP-05, JP-45 (above, manufactured by Nippon Vinegar Poval Co., Ltd.) and the like.

  The polyvinyl alcohol preferably used in the present invention includes modified polyvinyl alcohol in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate. Examples of the modified polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonion-modified polyvinyl alcohol, and vinyl alcohol polymers.

  The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 800 or more, and particularly preferably has an average degree of polymerization of 1,000 to 5,000. The degree of saponification is preferably 70 to 100 mol%, particularly preferably 80 to 99.5 mol%.

  Here, the degree of polymerization refers to the viscosity average degree of polymerization, which is measured according to JIS K6726: 1994. After the PVA is completely re-saponified and purified, the intrinsic viscosity [η] (dl / G) is obtained by the following equation.

  The weight average molecular weight of the water-soluble polymer is preferably 1,000 to 200,000, more preferably 3,000 to 40,000. In addition, in this specification, the value measured on the measurement conditions shown below using a gel permeation chromatography (GPC) is employ | adopted for a weight average molecular weight.

Solvent: 0.2M NaNO ₃ , NaH ₂ PO ₄ , pH 7
Column: Shodex Column Ohpak SB-802.5 HQ, 8x
300mm and Shodex Column Ohpak SB-805 HQ, 8x
300mm combination Column temperature: 45 ° C
Sample concentration: 0.1% by mass
Detector: RID-10A (manufactured by Shimadzu Corporation)
Pump: LC-20AD (manufactured by Shimadzu Corporation)
Flow rate: 1 ml / min
Calibration curve: Standard curve for Standard P-82 pullulan for Shodex Standard GFC (aqueous GPC) column.

  A curing agent may be used to cure the water-soluble polymer. The curing agent is not particularly limited as long as it causes a curing reaction with the water-soluble polymer. However, when the water-soluble polymer is polyvinyl alcohol, boric acid and its salt are preferable. In addition, as the curing agent, a compound having a group capable of reacting with the water-soluble polymer or a known compound that promotes the reaction between different groups of the water-soluble polymer can be used. Depending on the type, it is selected and used as appropriate. Specific examples of the curing agent other than boric acid and salts thereof include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane). N, N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde-based curing agents (formaldehyde, glycoxal, etc.), active halogen-based curing agents (2,4-dichloro-4- Hydroxy-1,3,5-s-triazine, etc.), active vinyl compounds (1,3,5-tris-acryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

  When the water-soluble polymer is gelatin, for example, organic hardeners such as vinyl sulfone compounds, urea-formalin condensates, melanin-formalin condensates, epoxy compounds, aziridine compounds, active olefins, isocyanate compounds, etc. Inorganic polyvalent metal salts such as chromium, aluminum and zirconium.

  When the polymer is a copolymer, the form of the copolymer may be any of a block copolymer, a random copolymer, a graft copolymer, and an alternating copolymer.

  When polyvinyl alcohol is used as the first polymer and the second polymer, the average saponification degree of polyvinyl alcohol contained in the high refractive index layer and the average saponification degree of polyvinyl alcohol contained in the low refractive index layer are: May be different.

  The average saponification degree of polyvinyl alcohol in each refractive index layer is determined in consideration of the content ratio in the refractive index layer. That is, the average degree of saponification = Σ (degree of saponification of each polyvinyl alcohol (mol%) × content of each polyvinyl alcohol in each refractive index layer (%) / 100 mass (%)). For example, the refractive index layer is polyvinyl alcohol A (content mass ratio in the refractive index layer (content mass (%) of each polyvinyl alcohol in each refractive index layer / 100 mass (%)): Wa, saponification degree: Sa ( mol%)), polyvinyl alcohol B (mass ratio in the refractive index layer: Wb, saponification degree: Sb (mol%)), polyvinyl alcohol C (mass ratio in the refractive index layer: Wc, saponification degree: When Sc (mol%) is included, the average degree of saponification = (Wa × Sa + Wb × Sb + Wc × Sc / (Wa + Wb + Wc)).

  In the case of using a water-soluble polymer, the content of the water-soluble polymer in the high refractive index layer and the low refractive index layer is not particularly limited, but relative to the total mass (solid content) of each refractive index layer , Preferably, it is 1-50 mass%, More preferably, it is 5-30 mass%.

  In order to adjust the refractive index difference, a fluorine-containing polymer may be used for the low refractive index layer. Examples of the fluorine-containing polymer include a polymer mainly containing a fluorine-containing unsaturated ethylenic monomer component.

  Examples of the fluorine-containing unsaturated ethylenic monomer include a fluorine-containing alkene, a fluorine-containing acrylic ester, a fluorine-containing methacrylate, a fluorine-containing vinyl ester, a fluorine-containing vinyl ether, and the like. And fluorine-containing unsaturated ethylenic monomers described in paragraph “0181” of Japanese Patent Publication. Examples of the monomer that can be copolymerized with the fluorine-containing monomer include monomers described in paragraph “0182” of JP2013-057969A.

(Metal oxide particles)
It is preferable that the high refractive index layer and the low refractive index layer according to the present invention further include metal oxide particles. By including metal oxide particles, the surface rigidity of the optical film can be increased, and wrinkles and undulations can be further reduced.

  Examples of the metal oxide particles contained in the high refractive index layer include titanium oxide, zirconium oxide, zinc oxide, alumina, colloidal alumina, lead titanate, red lead, yellow lead, zinc yellow, chromium oxide, and ferric oxide. , Iron black, copper oxide, magnesium oxide, magnesium hydroxide, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon, tin oxide and the like. Among these, metal oxide particles such as titanium oxide and zirconium oxide are preferable because they have an advantage that light in the ultraviolet region can be absorbed.

  In this embodiment, in order to form a transparent and higher refractive index layer having a higher refractive index, the high refractive index layer is made of high refractive index metal oxide fine particles such as titanium oxide and zirconium oxide, that is, titanium oxide fine particles, zirconium oxide. It is preferable to contain fine particles. In that case, it is more preferable to contain rutile (tetragonal) titanium oxide fine particles.

  The primary average particle diameter of the metal oxide particles contained in the high refractive index layer is preferably 30 nm or less, more preferably 1 to 30 nm, and even more preferably 5 to 15 nm. If the primary average particle diameter is 30 nm or less, it is preferable from the viewpoint of low haze and excellent visible light transmittance.

  As the titanium oxide particles according to the present invention, it is preferable to use particles in which the surface of an aqueous titanium oxide sol is modified to stabilize the dispersion state.

  As a method for preparing the aqueous titanium oxide sol, any conventionally known method can be used. For example, JP-A-63-17221, JP-A-7-819, JP-A-9-165218, Refer to the matters described in Kaihei 11-43327, JP-A-63-17221, JP-A-7-819, JP-A-9-165218, JP-A-11-43327, etc. it can.

  As for other methods for producing titanium oxide particles, for example, “Titanium oxide—physical properties and applied technology”, Kiyono Manabu, p. 255-258 (2000), Gihodo Publishing Co., Ltd., or paragraph number of International Publication No. 2007/039953. The method of the step (2) described in “0011” to “0023” can be referred to.

  Furthermore, as other methods for producing metal oxide particles including titanium oxide particles, the matters described in JP 2000-053421 A, JP 2000-063119 A, and the like can be referred to.

  Further, the titanium oxide particles may be coated with a silicon-containing hydrated oxide. Here, the “coating” means a state in which a silicon-containing hydrated oxide is attached to at least a part of the surface of the titanium oxide particles. That is, the surface of the titanium oxide particles used as the metal oxide particles may be completely covered with a silicon-containing hydrated oxide, and a part of the surface of the titanium oxide particles is a silicon-containing hydrated oxide. It may be coated. From the viewpoint that the refractive index of the coated titanium oxide particles is controlled by the coating amount of the silicon-containing hydrated oxide, it is preferable that a part of the surface of the titanium oxide particles is coated with the silicon-containing hydrated oxide. .

  The titanium oxide of the titanium oxide particles coated with the silicon-containing hydrated oxide may be a rutile type or an anatase type. The titanium oxide particles coated with a silicon-containing hydrated oxide are more preferably rutile-type titanium oxide particles coated with a silicon-containing hydrated oxide. This is because the rutile type titanium oxide particles have lower photocatalytic activity than the anatase type titanium oxide particles, and therefore the weather resistance of the high refractive index layer and the adjacent low refractive index layer is increased, and the refractive index is further increased. Because.

  The “silicon-containing hydrated oxide” in the present specification may be any of a hydrate of an inorganic silicon compound, a hydrolyzate and / or a condensate of an organosilicon compound, and in order to obtain the effects of the present invention. More preferably has a silanol group.

  The coating amount of the silicon-containing hydrated oxide is preferably 3 to 30% by mass, more preferably 3 to 10% by mass, and still more preferably 3 to 8% by mass. This is because when the coating amount is 30% by mass or less, a desired refractive index of the high refractive index layer can be obtained, and when the coating amount is 3% by mass or more, particles can be stably formed.

  As a method of coating the titanium oxide particles with a silicon-containing hydrated oxide, it can be produced by a conventionally known method. For example, JP-A-10-158015, JP-A-2000-204301, JP-A-2007 Reference can be made to the matters described in JP-A-246351.

  In addition, as the metal oxide particles contained in the high refractive index layer, core-shell particles produced by a known method can be used. For example, the core-shell particle manufactured by the method as described in Unexamined-Japanese-Patent No. 10-158015, Unexamined-Japanese-Patent No. 2000-053421, Unexamined-Japanese-Patent No. 2000-063119, and Unexamined-Japanese-Patent No. 2000-204301 is mentioned.

  The core-shell particles may be those in which the entire surface of the titanium oxide particles as a core is coated with a silicon-containing hydrated oxide, and a part of the surface of the titanium oxide particles as a core is covered with a silicon-containing hydrated oxide. It may be coated with.

  The metal oxide particles contained in the high refractive index layer may be surface-coated with a surface coating component such as aminocarboxylic acids such as picolinic acid, aminopolycarboxylic acids, pyridine derivatives and collagen peptides, and low molecular gelatin. It is considered that when the surface of the metal oxide particles is coated with a surface coating component, the compatibility and dispersibility with the water-soluble polymer are improved.

  Furthermore, the metal oxide particles used in the high refractive index layer are preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. This monodispersity is more preferably 30% or less, and still more preferably 0.1 to 20%.

  As content of the metal oxide particle in a high refractive index layer, it is preferable that it is 15-90 mass% with respect to 100 mass% of solid content of a high refractive index layer, and it is more preferable that it is 20-85 mass%. Preferably, it is 30-85 mass% from a viewpoint of a reflectance improvement, and is further more preferable.

  As the metal oxide particles contained in the low refractive index layer, silica (silicon dioxide) is preferably used, and specific examples include synthetic amorphous silica and colloidal silica. Among these, it is more preferable to use acidic colloidal silica sol, and it is particularly preferable to use colloidal silica dispersed in an organic solvent. In order to further reduce the refractive index, hollow fine particles having pores inside the particles may be used as the metal oxide particles contained in the low refractive index layer. In particular, hollow fine particles of silica (silicon dioxide) are used. preferable. Moreover, well-known metal oxide particles other than a silica can also be used.

  The metal oxide particles (preferably silicon dioxide) used for the low refractive index layer preferably have an average particle size of 3 to 100 nm. The average particle diameter of primary particles of silicon dioxide dispersed in a primary particle state (particle diameter in a dispersion state before coating) is more preferably 3 to 50 nm, and further preferably 3 to 40 nm. 3 to 20 nm is even more preferable, and 4 to 10 nm is particularly preferable. Moreover, as an average particle diameter of secondary particle | grains, it is preferable from a viewpoint with few hazes and being excellent in visible light permeability that it is 30 nm or less.

  The particle size of the metal oxide particles can also be obtained from the volume average particle size.

  The colloidal silica used in the present invention is obtained by heating and aging a silica sol obtained by metathesis with an acid of sodium silicate or the like and passing through an ion exchange resin layer. For example, JP-A-57-14091, JP-A-60-219083, JP-A-60-219084, JP-A-61-20792, JP-A-61-188183, JP-A-63-17807, JP-A-4-93284 No. 5, JP-A-5-278324, JP-A-6-92011, JP-A-6-183134, JP-A-6-297830, JP-A-7-81214, JP-A-7-101142. Disclosed in JP-A-7-179029, JP-A-7-137431, and International Publication No. 94/26530. It is.

  Such colloidal silica may be a synthetic product or a commercially available product. As a commercially available product, Snowtex (registered trademark) series sold by Nissan Chemical Industries, Ltd. (Snowtex (registered trademark) OS, OXS, S, OS, 20, 30, 40, O, N, C, etc.) Is mentioned.

  The surface of the colloidal silica may be cation-modified, or may be treated with Al, Ca, Mg, Ba or the like.

  Moreover, hollow particles can also be used as the metal oxide particles contained in the low refractive index layer. When hollow fine particles are used, the average particle pore size is preferably 3 to 70 nm, more preferably 5 to 50 nm, and even more preferably 5 to 45 nm. The average particle pore diameter of the hollow particles is the average value of the inner diameters of the hollow particles. If the average particle hole diameter of the hollow particles is within the above range, the refractive index of the low refractive index layer is sufficiently lowered. The average particle diameter is 50 or more at random, which can be observed as an ellipse in a circular, elliptical or substantially circular shape by electron microscope observation, and obtains the pore diameter of each particle. Is obtained. The average particle hole diameter means the minimum distance among the distances between the two parallel lines that surround the outer edge of the hole diameter that can be observed as a circle, an ellipse, or a substantially circle or ellipse.

  The content of the metal oxide particles in the low refractive index layer is preferably 20 to 90% by mass, and more preferably 30 to 85% by mass with respect to 100% by mass of the solid content of the low refractive index layer. More preferably, it is 40-70 mass%. When the content is 20% by mass or more, a desired refractive index is obtained.

(Polymer dispersant)
The high refractive index layer and the low refractive index layer may contain a polymer dispersant from the viewpoint of dispersion stability of the coating liquid. The polymer dispersant refers to a polymer dispersant having a weight average molecular weight of 10,000 or more. Preferred is a polymer having a hydroxyl group substituted at the side chain or terminal, for example, an acrylic polymer such as poly (sodium acrylate) or polyacrylamide and 2-ethylhexyl acrylate copolymerized, polyethylene glycol or the like. Examples include polyethers such as polypropylene glycol, polyvinyl alcohol, and the like. A commercially available polymer dispersant may be used, and examples of such a polymer dispersant include Marialim (registered trademark) AKM-0531 (manufactured by NOF Corporation). The content of the polymer dispersant is preferably 0.1 to 10% by mass in terms of solid content with respect to the refractive index layer.

[Emulsion resin]
The high refractive index layer and the low refractive index layer may further contain an emulsion resin. By including the emulsion resin, the flexibility of the film becomes higher and the workability such as sticking to glass is improved.

  Specifically, as the emulsion resin, materials described in paragraphs “0121” to “0124” of JP2013-148849A can be used.

[Other additives for refractive index layer]
The high refractive index layer and the low refractive index layer according to the present invention can contain various additives as necessary. For example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, JP-A-57-87989, JP-A-60. -72785, 61-146591, JP-A-1-95091 and JP-A-3-13376, various surfactants of anion, cation or nonion, 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266, etc., and optical brighteners, sulfuric acid, phosphoric acid, PH adjusters such as acetic acid, citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate, antifoaming agents, lubricants such as diethylene glycol Preservatives, anti-static agents may also contain various known additives such as a matting agent.

  The optical film of the present invention has a conductive layer, an antistatic layer, a gas barrier layer, an easy adhesion layer (adhesion layer), an adhesive layer, an antifouling layer, a deodorizing layer, a droplet layer, an easy layer for the purpose of adding further functions. Sliding layer, hard coat layer, abrasion resistant layer, antireflection layer, electromagnetic wave shielding layer, ultraviolet absorbing layer, infrared absorbing layer, printed layer, fluorescent light emitting layer, hologram layer, release layer, high refractive index layer of the present invention and You may have 1 or more of functional layers, such as infrared cut layers (a metal layer, a liquid crystal layer) other than a low refractive index layer, and a colored layer (visible light absorption layer).

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer which is one of the preferred functional layers is not particularly limited, and examples thereof include acrylic pressure-sensitive adhesives, silicon-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, polyvinyl butyral-based pressure-sensitive adhesives, and ethylene-vinyl acetate. Examples thereof include system adhesives. More specifically, materials, thicknesses, and the like described in paragraphs “0195” to “0198” of JP2013-007815A can be appropriately employed.

  In addition, examples of the constituent material of the hard coat layer, which is another preferable functional layer, include a thermosetting resin and an ultraviolet curable resin. More specifically, the configurations described in paragraphs “0139” to “0147” of JP2012-131130A can be appropriately employed.

The optical film of the present invention has a surface rigidity calculated by M × T ³ when the elastic modulus of the optical film is M (unit: mN / m ² ) and the film thickness of the optical film is T (unit: m). Is preferably in the range of 0.5 to 40 mN · m, more preferably in the range of 1.0 to 20 mN · m, and still more preferably in the range of 1.7 to 4.5 mN · m. . When the surface rigidity satisfies the above range, the optical film has appropriate rigidity, and wrinkles and waviness are further reduced. In addition, handling properties such as cutting property and winding property at the time of sticking work are further improved. The surface rigidity can be controlled by controlling the elastic modulus and film thickness of the substrate, the constituent material of the dielectric multilayer film, the number of layers, the film thickness, and the like.

(Dielectric multilayer film formation method)
The method for forming the dielectric multilayer film is not particularly limited, and includes, for example, a method of forming by polymer melt extrusion and stretching described in US Pat. No. 6,049,419 as described above, and a polymer. Examples thereof include a method in which a coating solution is applied by a roll coating method or the like and dried to form a film, either alone or in combination. Further, when the high refractive index layer and the low refractive index layer, which are preferred embodiments of the present invention, contain a water-soluble polymer and metal oxide particles, an aqueous high refractive index layer coating solution and a low refractive index layer coating are used. Examples include a method of alternately applying a liquid to the liquid and drying to form a laminate.

  As a method for wet-coating the aqueous high refractive index layer coating liquid and the low refractive index layer coating liquid alternately, the following coating methods are preferably used. For example, as described in roll coating method, rod bar coating method, air knife coating method, spray coating method, curtain coating method, US Pat. Nos. 2,761,419 and 2,761,791 These include a slide hopper coating method and an extrusion coating method. In addition, as a method of applying a plurality of layers in a multilayer manner, sequential multilayer coating or simultaneous multilayer coating may be used.

  Hereinafter, the simultaneous multilayer coating by the slide hopper coating method, which is a preferred production method (coating method) of the present invention, will be described in detail.

〔solvent〕
The solvent for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited, but water, an organic solvent, or a mixed solvent thereof is preferable.

  Examples of the organic solvent include alcohols such as methanol, ethanol, 2-propanol and 1-butanol, esters such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, diethyl ether, Examples thereof include ethers such as propylene glycol monomethyl ether and ethylene glycol monoethyl ether, amides such as dimethylformamide and N-methylpyrrolidone, and ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in combination of two or more.

  From the viewpoint of environment and simplicity of operation, the solvent for the coating solution is particularly preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate.

[Concentration of coating solution]
It is preferable that the density | concentration of the 1st polymer in the coating liquid for high refractive index layers is 0.5-10 mass%. Moreover, it is preferable that the density | concentration of the metal oxide particle in the coating liquid for high refractive index layers is 1-50 mass%.

  It is preferable that the density | concentration of the 2nd polymer in the coating liquid for low refractive index layers is 1-10 mass%. Moreover, it is preferable that the density | concentration of the metal oxide particle in the coating liquid for low refractive index layers is 1-50 mass%.

[Preparation method of coating solution]
The method for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited. For example, a polymer, metal oxide particles, and other additives that are added as necessary are added. The method of stirring and mixing is mentioned. At this time, the order of addition of the polymer, metal oxide particles, and other additives used as necessary is not particularly limited, and each component may be added and mixed sequentially with stirring, or once with stirring. It may be added to and mixed. If necessary, it is further adjusted to an appropriate viscosity using a solvent.

[Viscosity of coating solution]
The viscosity at 40 to 45 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer when performing simultaneous multilayer coating by the slide hopper coating method is preferably in the range of 5 to 150 mPa · s, and 10 to 100 mPa · s. The range of s is more preferable. The viscosity at 40 to 45 ° C. of the coating solution for high refractive index layer and the coating solution for low refractive index layer when performing simultaneous multilayer coating by the slide curtain coating method is preferably in the range of 5 to 1200 mPa · s, 25 A range of ˜500 mPa · s is more preferable.

  Further, the viscosity at 15 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is preferably 100 mPa · s or more, more preferably 100 to 30,000 mPa · s, and more preferably 3,000 to 30,000 mPa · s. s is more preferable, and 10,000 to 30,000 mPa · s is particularly preferable.

[Coating and drying method]
The coating and drying method is not particularly limited, but the high refractive index layer coating solution and the low refractive index layer coating solution are heated to 30 ° C. or higher to form a high refractive index layer coating solution and a low refractive index layer coating solution on the resin substrate. After the simultaneous multilayer coating of the refractive index layer coating liquid, the temperature of the formed coating film is preferably cooled (set) preferably to 1 to 15 ° C. and then dried at 10 ° C. or higher. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the uniformity improvement of the formed coating film.

  What is necessary is just to apply | coat so that the coating thickness of the coating liquid for high refractive index layers and the coating liquid for low refractive index layers may become the film thickness at the time of preferable drying shown in the term of the said dielectric multilayer film.

  Here, the set means a step of increasing the viscosity of the coating composition and reducing the fluidity of the substances in each layer and in each layer by means such as applying cold air to the coating film to lower the temperature. To do. A state in which the cold air is applied to the coating film from the surface and the finger is pressed against the surface of the coating film is defined as a set completion state.

  It is preferable that the time (setting time) from application of cold air to completion of setting after application is within 5 minutes. Further, the lower limit time is not particularly limited, but it is preferable to take 45 seconds or more. When the set time is in the above range, the components in the layer are sufficiently mixed, and the refractive index difference between the high refractive index layer and the low refractive index layer is sufficient.

  The set time can be adjusted by adjusting the concentration of the polymer and metal oxide particles, or by adding other components such as various known gelling agents such as gelatin, pectin, agar, carrageenan and gellan gum. Can be adjusted.

  The temperature of the cold air is preferably 0 to 25 ° C, and more preferably 5 to 10 ° C. Moreover, although the time for which a coating film is exposed to cold wind also depends on the conveyance speed of a coating film, it is preferable that it is 10 to 120 seconds.

[Use of optical film]
The optical film of the present invention is mainly weather resistant as a film for window pasting, a film for laminated glass, a film for agricultural greenhouses, etc., which are pasted on facilities exposed to sunlight for a long time such as outdoor windows of buildings and automobile windows. It is preferably used for the purpose of enhancing the properties. In particular, the optical film of the present invention is suitably applied to a member in which the optical film according to the present invention is bonded to a substrate such as glass or a glass substitute resin (resin glass) directly or via an adhesive. More preferably used as a film for glass. That is, the present invention also provides a laminated glass including the optical film of the present invention, a pair of intermediate films that sandwich the optical film, and a pair of laminated glass members that sandwich the optical film and the intermediate film. To do. Below, the structure of a laminated glass is demonstrated easily.

  A laminated glass is arrange | positioned in order of a laminated glass member, an intermediate film, an optical film, an intermediate film, and a laminated glass member from the incident light side, for example. The pair (two sheets) of laminated glass members may be the same type of material or different types of materials. Further, the pair (two) of intermediate films may have the same configuration or may have different configurations.

  The laminated glass may be a flat laminated glass or a curved laminated glass used for a car windshield.

  The two interlayer films used for the laminated glass contain a thermoplastic resin. The constituent materials of the two intermediate films may be the same or different. Moreover, the intermediate film which concerns on this invention can also be previously provided to the optical film as an adhesion layer.

  Preferable examples of the interlayer film according to the present invention include ethylene-vinyl acetate copolymer (EVA) and polyvinyl butyral (PVB). Further, in each intermediate film, in the range that does not inhibit the visible light transmittance, various kinds of infrared absorbing fine particles or ultraviolet absorbers are included, or coloring is performed by mixing pigments, so that the solar transmittance is 75. % Or less is more preferable.

  Examples of the fine particles that absorb infrared rays include fine metal particles such as Ag, Al, and Ti, fine metal nitride, and fine metal oxide particles, ITO, ATO, aluminum zinc composite oxide (AZO), and gallium-doped zinc oxide ( There are conductive transparent metal oxide fine particles such as GZO) and indium zinc composite oxide (IZO), and one or more of them can be selected and contained in the intermediate film to improve the heat insulation performance. In particular, conductive transparent metal oxide fine particles such as ITO, ATO, AZO, GZO, and IZO are preferable.

  When coloring EVA or PVB, known various pigments or various dyes that are generally used can be used as the colorant. Various dyes include anthraquinone dyes, azo dyes, acridine dyes, indigoid dyes, and various pigments include carbon black, red iron oxide, phthalocyanine blue, phthalocyanine green, bitumen, zinc white, azo pigments, selenium pigments. Etc. can be used. Further, a laminated polyvinyl acetal film obtained by coloring a polyvinyl acetal film with the dye or pigment and laminated with EVA or PVB may be used as the indoor intermediate film.

  As the laminated glass member, commercially available glass is used.

  Although the kind of glass is not specifically limited, Usually, soda-lime silica glass is used suitably. In this case, it may be a colorless transparent glass (clear glass) or a colored transparent glass such as a green colored transparent glass (green glass).

  Of the two glasses, the glass on the outdoor side close to the incident light is preferably colorless transparent glass (clear glass). The indoor glass far from the incident light side is preferably green colored transparent glass (green glass) or dark transparent glass. The green colored transparent glass (green glass) preferably has ultraviolet absorption performance and infrared absorption performance. By using these, the solar radiation energy can be reflected as much as possible on the outdoor side, and the solar radiation transmittance of the laminated glass can be further reduced.

  Moreover, although dark transparent glass is not specifically limited, For example, the soda-lime silica glass which contains iron in high concentration is mentioned suitably.

  When using the laminated glass of this invention for windows, such as a vehicle, it is preferable that both the thickness of an indoor side glass plate and an outdoor side glass plate is 1.5-3.0 mm. In this case, the indoor side glass plate and the outdoor side glass plate can have the same thickness or different thicknesses. The indoor side glass plate and the outdoor side glass plate may be flat or curved. Since vehicles, particularly automobile windows, are often curved, the shape of the indoor side glass plate and the outdoor side glass plate is often curved. In this case, the dielectric multilayer film is provided on the concave side of the outdoor glass plate. Further, three or more glass plates can be used as necessary.

  Although the manufacturing method of the laminated glass which concerns on this invention is not restrict | limited in particular, For example, it laminated | stacks in order of the laminated glass member, the intermediate film, the optical film, the intermediate film, and the laminated glass member, and protruded from the edge part of glass as needed. After removing the excess part of the optical film, 5-20 kg / cm ²The method of pressurizing with the pressure of this, heating at 100-150 degreeC for 10 to 60 minutes, and performing a pressure | pressure deaeration process and performing a combined process is mentioned.

  Specific examples of resin glass materials include polycarbonate resin, polysulfone resin, acrylic resin, polyolefin resin, polyether resin, polyester resin, polyamide resin, polysulfide resin, unsaturated polyester resin, epoxy resin, and melamine. Examples thereof include resins, phenol resins, diallyl phthalate resins, polyimide resins, urethane resins, polyvinyl acetate resins, polyvinyl alcohol resins, styrene resins, and vinyl chloride resins. Since the optical film of the present invention has a large thermal shrinkage rate even under a relatively low temperature condition of 130 ° C., when it is bonded to a resin glass having low heat resistance, thermoforming for removing wrinkles and undulations takes a short time. In addition, wrinkles and waviness can be efficiently reduced while suppressing deformation of the resin glass itself. Moreover, since the optical film of this invention contains a polymer, the refractive index difference with resin glass can be made small, and transparency and visibility, such as a laminated glass using resin glass, improve.

  When the optical film of the present invention is used as a laminated glass film or a window pasting film, the method of installing the optical film of the present invention is not particularly limited. However, from the viewpoint of more effectively reducing wrinkles and undulations, the longitudinal direction of the laminated glass member or window serving as the base is aligned with the direction in which the thermal shrinkage rate of the optical film of the present invention is large. It is preferable to do.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, the base material used by each Example and the comparative example was produced as follows.

(Preparation of base material)
Using a screw-type melt extruder, a polyethylene terephthalate ([η] = 0.64 dl / g, Tg = 78 ° C.) chip was melted at 280 ° C., extruded from a die, cooled by a casting drum in a conventional manner, and unstretched. A film was prepared. The unstretched film was longitudinally stretched at a temperature of 110 ° C. so that the magnification was 3.6 times in the longitudinal (longitudinal) direction. Then, transverse stretching was performed at 140 ° C. so that the magnification was 3.8 times in the transverse (width) direction, and biaxially stretched films were successively obtained.

  Next, a heat treatment was performed at 230 ° C. for 30 seconds, and then at 180 ° C., a relaxation heat treatment was performed while the clip interval was narrowed in the width direction and contracted 1.5% in the lateral direction, and then cooled to 90 ° C. as it was. In this way, a substrate 1 (thickness: 50 μm) was obtained.

  Furthermore, in said method, each condition was changed as shown in following Table 1, and the base materials 2-19 were produced.

[Example 1]
<Preparation of optical film 1>
(Preparation of coating solution for high refractive index layer)
28.9 parts by mass of a titanium oxide sol aqueous dispersion containing 20.0% by mass of rutile-type titanium oxide fine particles (volume average particle size: 10 nm), 5.41 parts by mass of an aqueous picolinic acid solution having a concentration of 14.8% by mass, and A titanium oxide dispersion was prepared by mixing with 3.92 parts by mass of a lithium hydroxide aqueous solution having a concentration of 2.1% by mass.

  Next, 10.3 parts by mass of pure water, 130 parts by mass of a 1.0% by mass aqueous solution of tamarind seed gum, and 5.0% by mass of polyvinyl alcohol (PVA-217, manufactured by Kuraray Co., Ltd.) 10.3 parts by mass Then, 17.3 parts by mass of an aqueous picolinic acid solution having a concentration of 14.8% by mass and 2.58 parts by mass of an aqueous boric acid solution having a concentration of 5.5% by mass were sequentially added with stirring. Into this, 38.2 parts by mass of the titanium oxide dispersion obtained above was added. Thereafter, 0.050 part by mass of a quaternary ammonium salt cationic surfactant (Nissan Co., Ltd., Nissan Cation (registered trademark) 2-DB-500E) having a concentration of 5% by mass was added as a surfactant. Pure water was added to prepare 223 parts by mass of a coating solution for a high refractive index layer as a whole.

(Preparation of coating solution for low refractive index layer)
Polyaluminum chloride (Takibine (registered trademark) # 1500, manufactured by Taki Chemical Co., Ltd.) aqueous solution having a concentration of 23.5% by mass, 21 parts by mass of colloidal silica (Snowtex (registered trademark) OXS, Nissan Chemical Industries, Ltd.) Co., Ltd.) 550 parts by mass of aqueous solution, 61 parts by mass of boric acid aqueous solution with a concentration of 3.0% by mass, and 4.75 parts by mass of lithium hydroxide aqueous solution with a concentration of 2.1% by mass are mixed using a high-pressure homogenizer disperser. And dispersed. Thereafter, pure water was added to prepare a dispersion of 1000 parts by mass of silicon oxide as a whole.

  Subsequently, the obtained dispersion of silicon oxide was heated to 45 ° C., and 100 parts by mass of pure water and 575 parts by mass of a 4.0% by mass aqueous solution of polyvinyl alcohol (PVA-235, manufactured by Kuraray Co., Ltd.) were contained therein. Added with stirring. Thereafter, as a surfactant, 0.55 parts by mass of a quaternary ammonium salt cationic surfactant having a concentration of 5% by mass (manufactured by NOF Corporation, Nissan Cation (registered trademark) 2-DB-500E) is added, A coating solution for a low refractive index layer was prepared.

(Preparation of adhesive layer coating solution)
A coating solution for the adhesive layer was prepared by containing 10.0% by mass of polyvinyl acetal resin in an ethanol solution of polyvinyl butyral (ESREC (registered trademark) BX-L, acetalization rate: 61 mol%, manufactured by Sekisui Chemical Co., Ltd.). .

(Preparation of coating solution for hard coat layer)
73 parts by mass of pentaerythritol tri / tetraacrylate (NK ester (registered trademark) A-TMM-3, manufactured by Shin-Nakamura Chemical Co., Ltd.), 5 parts by mass of Irgacure (registered trademark) 184 (produced by Ciba Japan) 1 part by mass of a silicone surfactant (KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.), 10 parts by mass of propylene glycol monomethyl ether, 70 parts by mass of methyl acetate, and 70 parts by mass of methyl ethyl ketone were obtained. The obtained mixed solution was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a hard coat layer.

(Preparation of optical film 1)
The outermost layers are both low on the substrate 1 obtained as described above, which is heated to 45 ° C. while keeping the coating solution for the low refractive index layer and the coating solution for the high refractive index layer obtained above at 45 ° C. Using a slide hopper coating device, a total of 16 layers are simultaneously laminated so that the refractive index layers are alternated, and the film thickness at the time of drying is alternately 150 nm for the low refractive index layers and 130 nm for the high refractive index layers. Application was performed. The confirmation of the mixed region (mixed layer) between layers and the measurement (confirmation) of the film thickness were performed by cutting the laminated film (optical reflective film sample) and cutting the cut surface with an XPS surface analyzer (high refractive index layer material (TiO _2)). ) And the abundance of the low refractive index layer material (SiO ₂ ), it was confirmed that the thickness of each layer described above was ensured.

  Immediately after application, 5 ° C. cold air was blown and set. At this time, even if the surface was touched with a finger, the time until the finger was lost (set time) was 5 minutes. After completion of the setting, warm air of 80 ° C. was blown and dried to form a dielectric multilayer film on the substrate 1. The refractive index of the high refractive index layer was 1.83, and the refractive index of the low refractive index layer was 1.49.

Using a micro gravure coater, the hard coat layer coating solution prepared above was applied to the surface of the dielectric multilayer film opposite to the surface in contact with the substrate 1, and the constant rate drying zone temperature was 50 ° C. After drying at a drying section temperature of 90 ° C., using an ultraviolet lamp, the irradiance of the irradiated part is 100 mW / cm ² , the irradiation amount is 0.2 J / cm ² , the coating layer is cured, and the dry film thickness is 6 μm. A hard coat layer was formed.

  Apply the coating solution for the adhesive layer prepared above on a PET substrate (used as a separator) with a thickness of 38 μm using a gravure coater in a coating amount of 3 μm after drying, and dry at 70 ° C. Then, an adhesive layer was formed, arranged so that the dielectric multilayer film of the substrate 1 and the adhesive layer were in contact, and bonded by a roll laminating method.

  Thus, the optical film 1 was produced.

[Examples 2 to 11]
Using the base materials 2 to 11 shown in Table 1 above, a dielectric multilayer film was formed in the same manner as in Example 1 to obtain optical films 2 to 11. In Examples 8 and 9, the direction of application to the glass was changed in the later-described evaluation, and the base material and the optical film itself were the same.

[Example 12]
An optical film including a dielectric multilayer film not including a metal oxide was produced as follows.

  The unit laminated films L1 to L5 were laminated on the substrate 12 to produce an optical film 12 in which a dielectric multilayer film was formed.

  The unit laminated films L1 to L5 are formed using polymethyl methacrylate (PMMA) as a low refractive index layer material and using polyethylene terephthalate (PET) as a high refractive index layer material (a low refractive index layer formed using PMMA). Is referred to as a PMMA layer, and a high refractive index layer formed using polyethylene terephthalate is referred to as a PET layer), and a PMMA layer (thickness t1) and a PET layer (thickness t2) of the same thickness are alternately laminated. did.

  The PMMA layer was formed by applying a solution obtained by dissolving PMMA in 2-methoxyethyl acetate by a roll coating method and drying it. The refractive index was 1.49. The PET layer was formed while melting PET pellets with an extruder. The refractive index of the PET layer was 1.65.

  The number of repetitions when the PMMA layer and the PET layer are one laminated unit was 20 (this is referred to as a unit laminated film L).

  The optical film 12 was obtained by changing the film thicknesses of the individual PMMA layers and the PET layers and laminating five unit laminated films (L1 to L5) each having a lamination number of 20 times.

  Table 2 below shows the thickness of the PMMA layer, the PET layer, the number of layers, the thickness of the unit multilayer film, and the thickness of the dielectric multilayer film of the unit multilayer films L1 to L5.

[Example 13]
An optical film 13 was produced in the same manner as in Example 10 except that a total of eight layers were simultaneously applied.

[Example 14]
An optical film 14 was produced in the same manner as in Example 10 except that a total of 22 layers were simultaneously applied.

[Example 15]
An optical film 15 was produced in the same manner as in Example 10 except that a total of 36 layers were simultaneously applied.

[Example 16]
An optical film 16 was produced in the same manner as in Example 1 except that the substrate 12 shown in Table 1 was used.

[Comparative Examples 1 to 7]
Using the base materials 13 to 19 shown in Table 1 above, dielectric multilayer films, hard coat layers, and adhesive layers were formed in the same manner as in Example 1 to obtain optical films 17 to 23.

[Evaluation of optical film]
The following performance evaluation was performed about the optical films 1-23 produced above.

<Heat shrinkage>
After storing the optical film at a temperature of 23 ° C. and a relative humidity of 55% RH for 24 hours, two marks are made at intervals of 100 mm in the width direction, and the distance A1 between the two marks in an unloaded state is measured with an optical microscope. And measured. Subsequently, the optical film was suspended in an oven at 130 ° C. and left for 30 minutes. After 30 minutes, the optical film was taken out of the oven and stored again for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 55% RH. Next, the distance A2 between the two marks on the unloaded optical film was measured using an optical microscope. From the measured distances A1 and A2, the thermal shrinkage rate of the optical film was calculated by the following formula. This measurement was performed in two directions of MD and TD of the optical film, and the difference in thermal shrinkage between MD and TD was calculated.

<Surface rigidity>
Using the film thickness (T) of the optical film and the elastic modulus (M) of the optical film measured according to JIS K7127: 1999, the numerical value calculated by the following formula is the value of the surface rigidity of the optical film. It was. The film thickness (T) of the optical film was measured using an electronic micrometer (K-312A type, manufactured by Anritsu Corporation) at a needle pressure of 30 g.

<Handling evaluation>
The obtained optical film was affixed on the glass for motor vehicles (Toyota Motor Corporation make, Vitz (trademark) rear glass) in the following procedures. The ease of work during handling (handability) and the finished quality after pasting were evaluated.

・ Pasting procedure (1) Cut the optical film into an appropriate area and shape to fit the size of the glass to be pasted (2) The side of the cut optical film opposite to the adhesive layer surface on the convex surface (outside) of the glass The optical film is thermoformed so as to match the curved surface of the glass while heating with a heat gun. (3) The optical film after the thermoforming is wound up once, and the commercially available neutral is placed on the concave side (indoor side) of the glass. An aqueous solution containing 1% by weight of detergent is sprayed evenly with a spray, etc., and the adhesive layer surface of the optical film after thermoforming is wound on the concave surface of the glass and attached using a plastic scraper while venting the air. (4) After the whole is uniformly applied, it is naturally dried for 3 days. (5) After natural drying, the finish (good drainage, breakage, etc.) is evaluated.

The handleability was evaluated from the following viewpoints. If it is more than △, it is practical:
-Can it be cut easily?-Can it be easily thermoformed?-Is it easy to wrinkle or break?-Can it be easily wound up?-The air on the adhesive surface can be easily removed.・ Check if water has drained and there is no adhesive peeling etc. << Evaluation criteria >>
◎: Very good ○: Good △: Somewhat difficult to handle, but practical use ×: Very difficult to handle

<Evaluation with laminated glass>
Evaluation of wrinkles and undulations when a laminated glass was produced using the optical films obtained in Examples and Comparative Examples was performed.

3 mm thick green glass (visible light transmittance: 81%, solar radiation transmittance: 63%, size: 50 cm × 50 cm) to be the indoor side glass, and 380 μm thick polyvinyl butyral to be the indoor side adhesive layer A 3 mm thick clear glass (visible light transmittance: 91%, solar radiation transmittance: 86%, size: 50 cm × 50 cm) to be a film, an optical film, and an outdoor glass was laminated in this order. After removing the excess part of the optical film that protruded from the edge of the glass, a pressure of about 10 to 14 kg / cm ² was applied, heated at 140 ° C. for 30 minutes, pressure degassed and subjected to a lamination process to produce a laminated glass did. The optical film was laminated so that the dielectric multilayer film was on the outdoor side.

  In the test room where the walls and ceiling were painted black, the appearance was visually evaluated while reflecting the fluorescent lamp on the ceiling onto the obtained laminated glass, and evaluated according to the following criteria. If it is more than Δ, it is practical.

◎: Wrinkles and waviness are not seen in the film inside the glass, and the appearance is very good ○: Slight wrinkles and waviness are seen in a part of the film inside the glass, but the appearance is good △: The film inside the glass is good Slight wrinkles and undulations are observed ×: In addition to wrinkles and undulations, gaps and cloudiness are observed inside the glass.

  In Example 9, the optical film used as described above was the same as that in Example 8, and was applied to an automotive glass and a laminated glass as follows.

Examples 1-8 and 10-16, Comparative Examples 1-7: The direction (Ta, MD) with a large heat-shrinkage rate and the horizontal direction (longitudinal direction) of glass match, and the direction with a small heat-shrinkage rate (Ta, MD) and the longitudinal direction (width direction) of the glass were made to coincide. Example 9: The direction with a large thermal shrinkage rate (Ta, MD) and the longitudinal direction (the width direction) of the glass were made to coincide with each other. The small direction (Ta, MD) and the horizontal direction (longitudinal direction) of the glass were matched.

  Furthermore, the column of comprehensive evaluation is evaluated according to the following criteria in consideration of evaluation results of wrinkles, undulations, and handleability. If it is more than Δ, it is practical.

◎: Very good ◎ or ○ only ○: Good △ There is one △, others are ◎
Δ: Permitted There is one Δ, but there is no X. X: There is one or more defective ×.

  The evaluation results are shown in Table 3 below.

  As is clear from the results shown in Table 3, even when the optical films of the examples are attached to glass having a large curvature (that is, having a small curvature radius) such as automotive glass, wrinkles and undulations are effectively reduced. I found out. In particular, in the optical films of Examples 5 to 8 having a surface rigidity in the range of 1.7 to 4.5 mN · m, wrinkles and undulations were further reduced and handleability was further improved.

<Evaluation with resin glass>
As the resin glass substrate, a transparent polycarbonate resin substrate having a curved surface shape similar to that of the glass for automobiles and having a plate thickness of 3 mm was prepared. This resin glass substrate was post-laminated to form an optical film in the same manner as in the above-described handling property evaluation, and the handling property in the resin glass was evaluated.

  The evaluation results were the same as the evaluation results of the handleability performed with the glass for automobiles in all Examples and Comparative Examples. In the comparative samples (Nos. 17 to 23) having a small heat shrinkage rate, it takes a long time for thermoforming with a heat gun to remove wrinkles and undulations, and the resin glass itself is deformed by the heat of the heat gun. It was. On the other hand, since the optical films of the examples have a large thermal shrinkage rate even at a relatively low temperature of 130 ° C., even in a resin glass having low heat resistance, the resin glass is hardly deformed and wrinkles and waviness can be reduced. It was found that it was excellent in handleability and finished quality was good.

  In addition, this application is based on the JP Patent application 2014-140711 for which it applied on July 8, 2014, The content of an indication is quoted as a whole by reference.

Claims (6)

An optical film having a dielectric multilayer film in which a high refractive index layer containing a first polymer and a low refractive index layer containing a second polymer are alternately laminated on a resin substrate,
When the optical film is held at 130 ° C. for 30 minutes, the thermal shrinkage rate in any one direction is Ta (unit:%), and the thermal shrinkage rate in the direction orthogonal to the arbitrary one direction is Tb (unit:%). ), An optical film satisfying all of the following formulas (1) to (3).
When the elastic modulus of the optical film is M (unit: mN / m ² ) and the film thickness is T (unit: m), the surface rigidity of the optical film calculated by M × T ³ is 1.7. The optical film according to claim 1, which is ˜4.5 mN · m.   The optical film according to claim 1, wherein the high refractive index layer and the low refractive index layer further include metal oxide particles.   The optical film according to claim 1, wherein the first polymer and the second polymer are water-soluble polymers.   The optical film according to any one of claims 1 to 4, wherein the number of laminated multilayer dielectric films is 10 or more and 34 or less. The optical film according to any one of claims 1 to 5,
A pair of intermediate films sandwiching the optical film;
A pair of laminated glass members sandwiching the optical film and the intermediate film;
Including laminated glass.