WO2022209567A1 - Anisotropic light-diffusing film and display device - Google Patents

Anisotropic light-diffusing film and display device Download PDF

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Publication number
WO2022209567A1
WO2022209567A1 PCT/JP2022/009244 JP2022009244W WO2022209567A1 WO 2022209567 A1 WO2022209567 A1 WO 2022209567A1 JP 2022009244 W JP2022009244 W JP 2022009244W WO 2022209567 A1 WO2022209567 A1 WO 2022209567A1
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angle
anisotropic light
light
central axis
scattering
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PCT/JP2022/009244
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French (fr)
Japanese (ja)
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昌央 加藤
純弥 荒島
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株式会社巴川製紙所
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Priority to JP2023510716A priority Critical patent/JPWO2022209567A1/ja
Priority to CN202280012694.3A priority patent/CN116802525A/en
Publication of WO2022209567A1 publication Critical patent/WO2022209567A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements

Definitions

  • the present invention relates to an anisotropic light-diffusing film and a display device equipped with the anisotropic light-diffusing film.
  • a “viewing angle” is one of the important characteristics of a display device, and it is generally considered that a wide viewing angle is preferable, except for applications such as prevention of prying eyes.
  • Methods for expanding the viewing angle of LCDs which are one of the most typical display devices, can be broadly classified into two.
  • the first one is a liquid crystal panel driving method such as TN, VA, or IPS, or a “method based on the internal design of the liquid crystal panel” such as the use of a retardation film for the purpose of optical compensation.
  • the second is a "method of adding members to the surface of a liquid crystal panel” such as using a diffusion film on the surface of a specific liquid crystal panel on the viewing side.
  • Methods by internal design of liquid crystal panel is the basic method, but in order to optimize for each individual application and usage environment, “Method by adding materials to the surface of liquid crystal panel” is more productive. is advantageous.
  • Patent Document 1 As a specific example of the "method by adding members to the surface of the liquid crystal panel", for example, (1) an "isotropic method” such as a light diffusion film having a light diffusion layer in which translucent fine particles are dispersed as shown in Patent Document 1 (2) A method of arranging a microlens array as shown in Patent Documents 2 and 3 or a "lens” such as a wave lens film on the liquid crystal panel surface; (3) Patent Document 4 There is a method of improving viewing angle characteristics by providing a "light control film having angle dependence" as shown in .
  • an “isotropic method” such as a light diffusion film having a light diffusion layer in which translucent fine particles are dispersed as shown in Patent Document 1
  • Patent Document 4 There is a method of improving viewing angle characteristics by providing a "light control film having angle dependence" as shown in .
  • an “anisotropic light diffusion film with anisotropy and directivity” that can change the amount of linearly transmitted light according to the incident angle of incident light can be used in a specific direction.
  • the viewing angle can be widened, the orientation of light is not steep, and it is easy to bond with other members.
  • Patent Document 5 a light diffusion film consisting of a single layer that has incident angle dependence in light diffusion and transmission and has two structural regions in the same film can effectively expand the light diffusion angle region. disclosed.
  • JP 2012-98526 A JP-A-8-166582 JP-A-7-239467 JP-A-7-146404 International publication WO2014/156420
  • the "isotropic diffuser" of Patent Document 1 produces a viewing angle widening effect in all directions, so even if it is desired to expand the viewing angle in a specific direction, the diffuser is also diffused outside the specific direction. As a result, there is a problem that it is difficult to reduce the luminance in the direction in which the viewing angle is desired to be widened.
  • Patent Documents 2 and 3 use light refraction and reflection, so the light orientation becomes steep, and the brightness tends to change suddenly due to changes in the viewing angle. Because of the interference, glare and moiré tend to occur.
  • the concave-convex structure of the lens is on the outermost surface, there is a problem that the effect tends to be reduced due to adhesion of dirt or the like.
  • attaching with an adhesive layer causes a problem that the unevenness is filled with the adhesive layer and the optical characteristics change, so the adhesive layer is used. Even if this is not done, there is a problem that the transmittance is lowered due to the presence of an air layer between the uneven structure and the film.
  • the "light control film having angle dependence" of Patent Document 4 has a steep change in the haze ratio with respect to the incident angle of light, so there is a problem that the brightness changes sharply due to the change in the viewing angle.
  • the "light diffusion film” of Patent Document 5 for example, in applications such as TV and digital signage, is rarely viewed from a deep vertical angle. If you want to expand the viewing angle in two directions, it is not only difficult to expand the viewing angle with good left-right balance by diffusing in the thickness direction in stages, but also the thickness increases due to the structure of the light diffusion film. There was a problem that it took a lot of work and cost.
  • an object of the present invention is to provide an anisotropic light diffusion film that enables widening of the viewing angle in two directions having vertical or horizontal symmetry and suppression of blurring while suppressing thickness and cost.
  • the present invention is as follows.
  • the present invention An anisotropic light diffusion film whose diffusibility changes depending on the incident angle of light,
  • the anisotropic light diffusion film has a matrix region and a columnar region that is a plurality of columnar structures having a different refractive index from the matrix region,
  • the scattering central axis A and the scattering central axis B are in an angle range of more than 0° and less than 90°
  • the azimuth angle ⁇ A of the scattering central axis A is 0°
  • the azimuth angle ⁇ B of the scattering central axis B is 170° to 190°
  • the angle between the normal line and the scattering center axis B be the scattering center axis angle ⁇ B
  • ⁇ B ⁇
  • An anisotropic light-diffusing film characterized in that A is ⁇
  • Tmin A be the minimum linear transmittance at the angle between the scattering central axis A and the normal
  • Tmin B be the minimum linear transmittance at the angle between the scattering central axis B and the normal.
  • ⁇ 5 percentage points is preferred.
  • the scattering central axis angle ⁇ A is preferably 10° to 60°. It is preferable that the haze value is 40% or more. It is preferable that the aspect ratio of the minor axis to the major axis in the cross section perpendicular to the alignment direction of the plurality of columnar structures is less than 2.
  • the present invention A display device comprising the anisotropic light diffusion film.
  • an anisotropic light diffusion film that has an enlarged viewing angle in two directions with vertical or horizontal symmetry and an effect of suppressing blurring, while suppressing thickness and costs.
  • FIG. 4 is an explanatory diagram showing the incident light angle dependency of an anisotropic light diffusion film.
  • FIG. 3 is a top view showing the surface structure of an anisotropic light-diffusing film; It is a schematic diagram which shows the example of an anisotropic light-diffusion film. It is a three-dimensional polar coordinate representation for explaining the scattering central axis in an anisotropic light diffusion film.
  • 4 is a graph showing an example of an optical profile in an anisotropic light diffusion film; It is a schematic diagram which shows the measuring method of the linear transmission light amount of an anisotropic light-diffusion film.
  • FIG. 3 is a schematic diagram showing the relationship between the central scattering axis A and the central scattering axis B in an anisotropic light diffusion film.
  • FIG. 2 is a schematic diagram showing a method for producing an anisotropic light-diffusing film of the present invention by optional step 1-3.
  • anisotropic light-diffusing film an anisotropic light-diffusing film having only one scattering central axis angle
  • anisotropic light-diffusing film having two scattering central axis angles anisotropic light-diffusing film having two scattering central axis angles
  • the anisotropic light diffusion film is a film having optical anisotropy, in which the linear transmittance [(amount of transmitted light in the linear direction of incident light)/(amount of incident light)] changes depending on the angle of incidence of light. . That is, with respect to incident light to the anisotropic light diffusion film, incident light within a predetermined angle range is transmitted while maintaining linearity, and incident light within other angle ranges exhibits diffusing properties.
  • the anisotropic light diffusion film which is an example shown in FIG. 1, exhibits diffusibility when the incident angle is 20° to 50°, and exhibits no diffusivity at other incident angles and exhibits linear transmittance.
  • the anisotropic light diffusion film has a matrix region and columnar regions, which are a plurality of columnar structures having different refractive indices from those of the matrix region.
  • the plurality of columnar structures contained in the anisotropic light-diffusing film are usually oriented and extended from one surface to the other surface of the anisotropic light-diffusing film (see FIG. 3).
  • the length of the columnar structure is not particularly limited, and may be a length that penetrates from one surface of the anisotropic light diffusion film to the other surface, or a length that does not reach from one surface to the other surface.
  • the shape of the cross section perpendicular to the column axis of the plurality of columnar structures included in the anisotropic light diffusion film can be a shape having a minor axis and a major axis.
  • the cross-sectional shape of the columnar structure is not particularly limited, and may be circular, elliptical, or polygonal, for example.
  • the minor axis and the major axis are equal; in the case of an ellipse, the minor axis is the length of the minor axis and the major axis is the length of the major axis;
  • the shortest length can be used as the short axis, and the longest length can be used as the long axis.
  • FIG. 2 shows a plurality of columnar structures viewed from the surface direction of the anisotropic light diffusion film.
  • LA represents the major axis
  • SA represents the minor axis.
  • the aspect ratio is 1 or more and less than 2, when light parallel to the axial direction of the columnar structure is irradiated, the transmitted light diffuses isotropically ⁇ see FIG. 3(a) ⁇ .
  • the aspect ratio is 2 to 20
  • diffusion occurs with an anisotropy corresponding to the aspect ratio ⁇ see FIG. 3(b) ⁇ .
  • the minor axis and major axis of the columnar structures were obtained by observing a cross section of the anisotropic light diffusion film perpendicular to the columnar axis with an optical microscope, and measuring the minor axis and major axis of each of 20 arbitrarily selected columnar structures. These average values can be used.
  • the difference in refractive index means that at least part of the light incident on the anisotropic light-diffusing film is reflected at the interface between the matrix region and the columnar region, and is not particularly limited.
  • the difference in refractive index between the matrix region and the columnar region should be 0.001 or more.
  • n 1 sin ⁇ 1 n 2 sin ⁇ 2 between the incident light angle ⁇ 1 and the refraction angle ⁇ 2. relationship is established.
  • the orientation direction (refractive angle) of the columnar regions is about 19°.
  • FIG. 4 is a three-dimensional polar coordinate representation for explaining the scattering center axis P in the anisotropic light diffusion film.
  • the scattering central axis means the direction in which the light diffusibility coincides with the incident light angle of light having approximately symmetry with respect to the incident light angle when the incident light angle to the anisotropic light diffusion film is changed.
  • the incident light angle at this time is the linear transmittance in the optical profile (FIG. 5 as an example) obtained by measuring the linear transmission light amount of the anisotropic light diffusion film and plotting the calculated linear transmittance for each incident light angle. It is the angle of the approximate central portion (the central portion of the diffusion region) sandwiched between the minimum values.
  • the scattering center axis is the polar angle ⁇ and the azimuth when the surface of the anisotropic light diffusion film is the xy plane and the normal line to the surface of the anisotropic light diffusion film is the z axis.
  • angle ⁇ the angle ⁇
  • the polar angle ⁇ (0° ⁇ 90°) formed by the normal to the anisotropic light diffusion film (z-axis shown in FIG. 4) and the columnar region can be defined as the scattering central axis angle.
  • the angle of the axial direction of the plurality of columnar structures can be adjusted within a desired range by changing the direction of the irradiated light beam.
  • the anisotropic light diffusing film has light diffusing properties dependent on the incident light angle, in which the linear transmittance changes depending on the incident light angle.
  • the curve showing the incident light angle dependence of light diffusion as shown in FIG. 5 is hereinafter referred to as an "optical profile”.
  • An optical profile can be created, for example, as follows.
  • An anisotropic light diffusion film is placed between the light source 1 and the detector 2, as shown in FIG.
  • the incident light angle is 0° when the irradiation light I from the light source 1 is incident from the normal direction of the anisotropic light diffusion film.
  • the anisotropic light diffusion film is arranged so as to be freely rotatable with the straight line V as the axis of rotation, and the light source 1 and the detector 2 are fixed. That is, according to this method, a sample (anisotropic light diffusion film) is placed between the light source 1 and the detector 2, and the sample is transmitted straight through while changing the angle with the straight line V on the sample surface as the axis of rotation for detection.
  • the linear transmitted light amount entering the device 2 is measured (this straight line V is a line on the anisotropic light diffusion film perpendicular to the tilted azimuth of the central axis of scattering). After that, the linear transmittance is calculated from the amount of linearly transmitted light, and the linear transmittance is plotted for each angle to create an optical profile.
  • the optical profile does not directly express the light diffusibility, but if it is interpreted that the diffuse transmittance increases due to the decrease in the in-line transmittance, it generally indicates the light diffusivity. It can be said that
  • a normal isotropic light diffusion film exhibits a mountain-shaped optical profile with a peak at an incident light angle near 0°.
  • the anisotropic light diffusion film has the property that the incident light is strongly diffused in the incident light angle range close to the scattering center axis, but the diffusion weakens and the linear transmittance increases in the incident light angle range beyond that.
  • the optical profile shifts so that the linear transmittance decreases at incident light angles near the scattering center axis angle (the troughs of the optical profile move to the scattering center axis angle side). do).
  • the linear transmittance of light incident on the anisotropic light diffusion film at the incident angle at which the linear transmittance is minimized is called the minimum linear transmittance.
  • the angle range of the two incident light angles with respect to the intermediate value of the linear transmittance between the maximum linear transmittance and the minimum linear transmittance is called a diffusion region (the width of this diffusion region is the "diffusion width"). , is called a non-diffusion area (transmissive area).
  • the haze value (total haze) of an anisotropic light-diffusing film is an index showing the diffusibility of the anisotropic light-diffusing film. As the haze value increases, the diffusibility of the anisotropic light-diffusing film increases.
  • a method for measuring the haze value is not particularly limited, and it can be measured by a known method. For example, it can be measured according to JIS K7136-1:2000 "Plastics - Determination of haze of transparent materials".
  • the anisotropic light-diffusing film according to the present invention includes, in one layer, a first columnar region composed of a plurality of columnar structures inclined in a certain direction with respect to the normal direction of the anisotropic light-diffusing film, and an anisotropic light-diffusing film. It is composed of a plurality of columnar structures inclined in a different direction from the first columnar regions with respect to the normal direction, and has a second columnar region extending in a different direction from the first columnar regions.
  • the anisotropic light diffusion film according to the present invention has such a configuration, the first scattering center axis (scattering center axis A) based on the first columnar region and the second scattering center axis based on the second columnar region As the scattering center axis (scattering center axis B), one layer has two scattering center axes (see FIG. 7(1)).
  • both the first columnar region and the second columnar region extend from one surface to the other surface of the anisotropic light-diffusing film in the normal direction of the anisotropic light-diffusing film. It has a tilted structure. Therefore, "the positional relationship between the scattering central axis A and the scattering central axis B" and “the scattering central axis A and the scattering central axis B when the scattering central axis B is rotated 180° around the normal line of the anisotropic light diffusion film "positional relationship with” is different. Therefore, in the present invention, the positional relationship between the scattering central axes A and B is indicated by the above-described polar angle ⁇ and azimuth angle ⁇ .
  • the scattering center axis A is on the X axis, and its azimuth angle ⁇ A ( The 3 o'clock direction in FIG. 7(1) is assumed to be 0°.
  • the angle ⁇ B formed with the line is 170° to 190°, preferably 175° to 185°, still more preferably 180° (FIG. 7(2) shows a preferred example).
  • the angle of the normal direction of the anisotropic light-diffusing film when the angle of the normal direction of the anisotropic light-diffusing film is 0°, it is more than 0° and less than 90° (preferably 10° to 60°, more preferably 20° to 45° ) have two scattering central axes. That is, as shown in FIG.
  • the angle between the normal to the anisotropic light-diffusing film and the scattering center axis A is the scattering center axis angle ⁇ A
  • two scattering central axes that satisfy the above relationship are present inside a single layer of an anisotropic light diffusion film, thereby suppressing the thickness and providing excellent optical properties. It becomes an anisotropic light diffusing film having a , and it is possible to expand the viewing angle in two directions having symmetry, such as up and down or left and right.
  • the anisotropic light-diffusing film according to the present invention has a first columnar region that forms the central scattering axis A and a second columnar region that forms the central scattering axis B, which extend in different directions. There are two columnar regions.
  • common structures (minor axis, major axis, aspect ratio) of the plurality of columnar structures included in the first columnar region and the plurality of columnar structures included in the second columnar region will be described.
  • the structure of the plurality of columnar structures included in the first columnar region and the structure of the plurality of columnar structures included in the second columnar region may be the same or different.
  • the first columnar region and the second columnar region of the present invention are obtained by irradiating light from two different angles to cure the resin.
  • the structure of the plurality of columnar structures included in the columnar region and the structure of the plurality of columnar structures included in the second columnar region can be individually adjusted.
  • the average short diameter (average short diameter) of the columnar structures is preferably 0.5 ⁇ m or more, more preferably 1.0 ⁇ m or more, and even more preferably 1.5 ⁇ m or more.
  • the average minor axis of the columnar structures is preferably 5.0 ⁇ m or less, more preferably 4.0 ⁇ m or less, and even more preferably 3.0 ⁇ m or less.
  • the lower limit and upper limit of the minor axis of these columnar structures can be combined as appropriate.
  • the average major axis (average major axis) of the columnar structures is preferably 0.5 ⁇ m or more, more preferably 1.0 ⁇ m or more, and even more preferably 1.5 ⁇ m or more.
  • the average length of the columnar structures is preferably 100 ⁇ m or less, more preferably 50 ⁇ m or less, and even more preferably 30 ⁇ m or less.
  • the lower limit and upper limit of the major axis of these columnar structures can be combined as appropriate.
  • the ratio of the average major axis to the average minor axis of the columnar structure (average major axis/average minor axis), that is, the aspect ratio is preferably 1 to 20, more preferably less than 2.
  • the aspect ratio of the plurality of columnar structures included in the first columnar region and the plurality of columnar structures included in the second columnar region is preferably 1:2 to 2:1, more preferably 2:3 to 3:2, still more preferably 9:10 to 10:9.
  • the thickness of the anisotropic light-diffusing film is preferably 15 ⁇ m to 100 ⁇ m, more preferably 30 ⁇ m to 80 ⁇ m. By setting it in such a range, it is possible to reduce manufacturing costs such as material costs and costs required for UV irradiation, and to achieve a sufficient effect of improving visual dependence.
  • the anisotropic light-diffusing film according to the present invention has two scattering central axes. Therefore, in the optical profile of the anisotropic light diffusion film according to the present invention, the linear transmittance in the incident light angle range corresponding to the scattering central axis A and the linear transmittance in the incident light angle range corresponding to the scattering central axis B are exist.
  • the anisotropic light-diffusing film according to the present invention has a minimum linear transmittance Tmin A at the angle between the scattering central axis A and the normal to the anisotropic light-diffusing film, the scattering central axis B, and the normal to the anisotropic light-diffusing film.
  • which is the absolute value of the difference from the minimum linear transmittance Tmin B at the angle between is more preferable.
  • the anisotropic light-diffusing film according to the present invention preferably has a maximum in-line transmittance of 50% or less, more preferably 30% or less. By doing so, the symmetry of the anisotropic light-diffusing film is improved, and it is possible to expand the viewing angle in two directions having vertical or horizontal symmetry.
  • the in-line transmittance is adjusted by the refractive index of the material of the anisotropic light diffusion film (difference in refractive index when multiple resins are used), film thickness of the coating film, UV illuminance, temperature during structure formation, and other curing conditions. be able to.
  • the in-line transmittance tends to decrease, for example, when UV irradiation is performed, the thicker the coating film, the higher the temperature of the coating film, and the greater the refractive index difference in the case of using a plurality of resins.
  • the haze value of the anisotropic light-diffusing film is preferably 40% or more, more preferably 50% or more. By setting it as such a range, the effect of this invention can be heightened more.
  • the haze value can be adjusted by adjusting the refractive index of the material of the anisotropic light diffusion film (difference in refractive index when multiple resins are used), coating film thickness, UV illumination, and curing conditions such as temperature during structure formation. can. For example, when performing UV irradiation, the irradiation angle is close to the normal direction of the coating film, the layer thickness of the coating film is thick, the temperature of the coating film is high, and the refractive index difference when using a plurality of resins is It tends to increase as the size increases.
  • Raw materials for the anisotropic light-diffusing film will be described in the order of (1) photopolymerizable compound, (2) photoinitiator, (3) blending amount, and other optional components.
  • the photopolymerizable compound comprises a photopolymerizable compound selected from macromonomers, polymers, oligomers, and monomers having radically polymerizable or cationic polymerizable functional groups, and a photoinitiator, and emits ultraviolet rays and/or visible rays. It is a material that polymerizes and hardens when irradiated.
  • (Meth)acrylate means that it may be either acrylate or methacrylate.
  • Radically polymerizable compounds mainly contain one or more unsaturated double bonds in the molecule, and specific examples include epoxy acrylates, urethane acrylates, polyester acrylates, polyether acrylates, polybutadiene acrylates, silicone acrylates, and the like. and 2-ethylhexyl acrylate, isoamyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isonorbornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate.
  • 2-acryloyloxyphthalic acid dicyclopentenyl acrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, EO adduct diacrylate of bisphenol A, trimethylolpropane triacrylate, Acrylate monomers such as EO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexaacrylate. Also, these compounds may be used alone or in combination. Methacrylates can also be used, but acrylates are generally preferable to methacrylates because they have a faster photopolymerization rate.
  • a compound having one or more epoxy groups, vinyl ether groups, or oxetane groups in the molecule can be used as the cationic polymerizable compound.
  • Compounds having an epoxy group include 2-ethylhexyl diglycol glycidyl ether, biphenyl glycidyl ether, bisphenol A, hydrogenated bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetrachloro Diglycidyl ethers of bisphenols such as bisphenol A and tetrabromobisphenol A, polyglycidyl ethers of novolak resins such as phenol novolak, cresol novolak, brominated phenol novolak and ortho-cresol novolak, ethylene glycol, polyethylene glycol, polypropylene glycol, diglycidyl ethers of alkylene glycols such as butanediol, 1,6-hex
  • compounds having an epoxy group include 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate and 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy).
  • Examples of compounds having a vinyl ether group include diethylene glycol divinyl ether, triethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, hydroxybutyl vinyl ether, ethyl vinyl ether, dodecyl vinyl ether, trimethylolpropane tri vinyl ether, propenyl ether propylene carbonate, etc., but not limited thereto.
  • Vinyl ether compounds are generally cationic polymerizable, but can be radically polymerized by combining them with acrylates.
  • the above cationic polymerizable compounds may be used alone or in combination.
  • the photopolymerizable compound is not limited to those mentioned above.
  • fluorine atoms may be introduced into the photopolymerizable compound in order to lower the refractive index.
  • a sulfur atom (S), a bromine atom (Br), and various metal atoms may be introduced.
  • ultrafine particles made of metal oxides with a high refractive index such as titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), tin oxide (SnO x ), etc. It is also effective to add functional ultrafine particles having a photopolymerizable functional group such as an acrylic group, a methacrylic group, or an epoxy group introduced to the surface of the above-described photopolymerizable compound.
  • a photopolymerizable compound having a silicone skeleton is preferably used as the photopolymerizable compound.
  • a photopolymerizable compound having a silicone skeleton is oriented and polymerized and cured along with its structure (mainly ether bonds) to form a low refractive index region, a high refractive index region, or a low refractive index region and a high refractive index region. Form.
  • a photopolymerizable compound having a silicone skeleton it becomes easier to incline the columnar structure, and light collection in the front direction is improved.
  • the low refractive index region corresponds to either the columnar region or the matrix region, and the other corresponds to the high refractive index region.
  • silicone resin which is a cured product of a photopolymerizable compound having a silicone skeleton
  • silicone resins contain more silicon (Si) than compounds that do not have a silicone skeleton. amount can be checked.
  • a photopolymerizable compound having a silicone skeleton is a monomer, oligomer, prepolymer or macromonomer having a radically polymerizable or cationic polymerizable functional group.
  • radically polymerizable functional groups include acryloyl groups, methacryloyl groups, and allyl groups
  • examples of cationic polymerizable functional groups include epoxy groups and oxetane groups.
  • Compounds having a silicone skeleton may have insufficient compatibility with other compounds due to their structure. In such cases, the compatibility can be enhanced by urethanization.
  • a silicone/urethane/(meth)acrylate having an acryloyl group or a methacryloyl group at its end is preferably used.
  • the weight average molecular weight (Mw) of the photopolymerizable compound having a silicone skeleton is preferably in the range of 500 to 50,000. It is more preferably in the range of 2,000 to 20,000.
  • Mw weight average molecular weight
  • a sufficient photocuring reaction occurs, and the silicone resin present in each anisotropic light-diffusing film of the anisotropic light-diffusing film is easily oriented. With the orientation of the silicone resin, it becomes easier to tilt the scattering central axis.
  • silicone skeleton examples include those represented by the following general formula (1).
  • R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently a methyl group, an alkyl group, a fluoroalkyl group, a phenyl group, an epoxy group, an amino group and a carboxyl group. , a polyether group, an acryloyl group, a methacryloyl group, and the like.
  • n is preferably an integer of 1-500.
  • thermoplastic resins and thermosetting resins can be used as compounds that do not have a silicone skeleton, and these can also be used in combination.
  • a polymer, oligomer, or monomer having a radically polymerizable or cationic polymerizable functional group can be used (however, it does not have a silicone skeleton).
  • Thermoplastic resins include polyesters, polyethers, polyurethanes, polyamides, polystyrenes, polycarbonates, polyacetals, polyvinyl acetates, acrylic resins and their copolymers and modified products.
  • the anisotropic light diffusion film is formed by dissolving the resin in a solvent that dissolves the thermoplastic resin, applying and drying the resin, and then curing the photopolymerizable compound having a silicone skeleton with ultraviolet rays.
  • Thermosetting resins include epoxy resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters and their copolymers and modified products.
  • a thermosetting resin the photopolymerizable compound having a silicone skeleton is cured with ultraviolet light and then heated appropriately to cure the thermosetting resin and form an anisotropic light diffusion film.
  • a photopolymerizable compound is most preferable as a compound that does not have a silicone skeleton. It is easy to separate the low refractive index region and the high refractive index region, and when using a thermoplastic resin, no solvent is required and no drying process is required. It is excellent in productivity because it does not require a thermosetting process unlike a thermosetting resin.
  • Photoinitiators capable of polymerizing radically polymerizable compounds include benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2- diethoxyacetophenone, benzyl dimethyl ketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2 -methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1 -one, bis(cyclopentadienyl)-bis[2,6-difluoride
  • the photoinitiator of the cationically polymerizable compound is a compound that generates an acid upon irradiation with light and can polymerize the above-described cationically polymerizable compound with the generated acid.
  • onium salts and metallocene complexes are It is preferably used.
  • onium salts diazonium salts , sulfonium salts , iodonium salts , phosphonium salts, selenium salts and the like are used. Used. Specific examples include 4-chlorobenzenediazonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl)diphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl)diphenyl Sulfonium hexafluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluoroantimonate, bis[4-(diphen
  • the photoinitiator is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, and still more preferably about 0.1 to 5 parts by mass with respect to 100 parts by mass of the photopolymerizable compound. be. This is because if the amount is less than 0.01 part by mass, the photocurability is reduced, and if the amount is more than 10 parts by mass, only the surface is cured and the internal curability is reduced. This is because it leads to inhibition of the formation of
  • the photoinitiator is usually used by directly dissolving the powder in the photopolymerizable compound, but if the solubility is poor, the photoinitiator should be pre-dissolved in a very small amount of solvent at a high concentration.
  • a solvent is more preferably photopolymerizable, and specific examples thereof include propylene carbonate and ⁇ -butyrolactone.
  • various known dyes and sensitizers can be added to improve the photopolymerizability.
  • thermosetting initiator capable of curing the photopolymerizable compound by heating can be used together with the photoinitiator.
  • thermosetting initiator capable of curing the photopolymerizable compound by heating
  • An anisotropic light-diffusing film can be formed by curing a composition containing a single photopolymerizable compound or a mixture of multiple photopolymerizable compounds.
  • An anisotropic light diffusion film can also be formed by curing a mixture of a photopolymerizable compound and a non-photocurable polymer resin.
  • Polymer resins that can be used here include acrylic resins, styrene resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, Polyvinyl butyral resin etc. are mentioned. These polymer resins and photopolymerizable compounds must have sufficient compatibility before photocuring, and various organic solvents and plasticizers are used to ensure this compatibility. is also possible.
  • acrylate When acrylate is used as the photopolymerizable compound, it is preferable to select from acrylic resins as the polymer resin in terms of compatibility.
  • the mass ratio of the photopolymerizable compound having a silicone skeleton to the compound having no silicone skeleton is preferably in the range of 15:85 to 85:15. More preferably, it is in the range of 30:70 to 70:30. Within this range, phase separation between the low-refractive-index region and the high-refractive-index region is facilitated, and the columnar structures are easily tilted. If the ratio of the photopolymerizable compound having a silicone skeleton is less than the lower limit or more than the upper limit, phase separation will be difficult to progress, and the columnar structure will be difficult to tilt.
  • silicone/urethane/(meth)acrylate as a photopolymerizable compound having a silicone skeleton improves compatibility with compounds that do not have a silicone skeleton. As a result, the columnar structure can be tilted even if the mixing ratio of the materials is widened.
  • a solvent for preparing a composition containing a photopolymerizable compound for example, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, etc. can be used.
  • the paint containing the photopolymerizable compound described above is coated on a suitable substrate such as a transparent PET film to form a sheet, and if necessary dried to form a film, forming an uncured resin composition layer.
  • a suitable substrate such as a transparent PET film
  • an uncured resin composition layer By irradiating light onto this uncured resin composition layer, an anisotropic light diffusion film can be produced.
  • Step 1-1 Step of providing an uncured resin composition layer on a substrate
  • Step 1-2 Step of obtaining parallel light from a light source
  • Optional step 1-3 Directive light
  • the anisotropic light-diffusing film according to the present invention has two scattering central axes (scattering central axis A and scattering central axis B).
  • scattering central axis A and scattering central axis B are extended in a form corresponding to the irradiation direction of each light.
  • the structure of the columnar structures included in the first columnar region and the structure of the columnar structures included in the second columnar region can be made different. can.
  • a prism sheet on the path of the light beam and dividing the light beam into two directions for irradiation, it is possible to irradiate the light beam from two directions.
  • light beams of the same quality are irradiated from two directions except that the irradiation angles of the light beams are different.
  • a plurality of columnar structures in the columnar region can be substantially the same structure except for the tilt direction.
  • Step 1-1 Step of Providing Uncured Resin Composition Layer on Substrate>
  • a usual coating method or printing method is applied to the technique of providing the coating material containing the photopolymerizable compound on the substrate in the form of a sheet as an uncured resin composition layer. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calender coating, dam coating, dip coating , coating such as die coating, intaglio printing such as gravure printing, and printing such as stencil printing such as screen printing can be used. If the paint has a low viscosity, a weir of a certain height can be provided around the substrate and the paint can be cast into the area surrounded by this weir.
  • step 1-1 in order to prevent oxygen inhibition of the uncured resin composition layer and efficiently form a columnar structure, which is a feature of an anisotropic light diffusion film, on the light irradiation side of the uncured resin composition layer It is also possible to laminate a mask that is in close contact and locally changes the irradiation intensity of light.
  • a light absorbing filler such as carbon is dispersed in the matrix. Part of the incident light is absorbed by the carbon, but the rest of the incident light is sufficiently transmitted. things are preferred.
  • a matrix include transparent plastics such as PET, TAC, PVAc, PVA, acryl, and polyethylene; inorganic materials such as glass and quartz; It may contain a pigment that absorbs the
  • Step 1-2 Step of Obtaining Parallel Light from Light Source>
  • a short-arc ultraviolet light source is usually used, and specifically, a high-pressure mercury lamp, a low-pressure mercury lamp, a methhalide lamp, a xenon lamp, or the like can be used. At this time, it is necessary to obtain a light beam parallel to the desired scattering center axis.
  • an optical lens such as a Fresnel lens for irradiation, it can be obtained by arranging a reflecting mirror behind the light source so that light is emitted as a point light source in a predetermined direction.
  • Optional step 1-3 is a step of making parallel light beams incident on a directional diffusion element to obtain light beams with directivity.
  • FIG. 8 is a schematic diagram showing a method for manufacturing an anisotropic light-diffusing film of the present invention by optional step 1-3.
  • the directional diffusing elements 301 and 302 used in the optional step 1-3 should just impart directivity to the parallel light beams D incident from the light source 300 .
  • FIG. 8 describes that the directional light E is incident on the uncured resin composition layer 303 in such a manner that it diffuses much in the X direction and scarcely diffuses in the Y direction.
  • needle-like fillers having a high aspect ratio are contained in the directional diffusion elements 301 and 302, and the needle-like fillers are arranged in the Y direction in the long axis direction. It is possible to adopt a method of orienting such that the Directional diffusion elements 301 and 302 can use various methods other than the method of using needle-like fillers.
  • the aspect ratio of the light E with directivity is preferably 2-20.
  • a columnar region having an aspect ratio substantially corresponding to the aspect ratio is formed.
  • the upper limit of the aspect ratio is more preferably 10 or less, even more preferably 5 or less. If the aspect ratio exceeds 20, interference rainbows and glare may occur.
  • the sizes of the columnar regions to be formed can be appropriately determined.
  • the anisotropic light-diffusing film of this embodiment can be obtained in both FIGS.
  • the difference between FIGS. 8A and 8B is that the spread of the light E with directivity is large in FIG. 8A and small in FIG. 8B.
  • the size of the columnar region differs depending on the size of the spread of the light E having directivity.
  • the spread of the light E with directivity mainly depends on the types of the directional diffusion elements 301 and 302 and the distance from the uncured resin composition layer 303 .
  • Step 1-4 Step of curing the uncured resin composition layer>
  • the light beam that is applied to the uncured resin composition layer to cure the uncured resin composition layer must contain a wavelength capable of curing the photopolymerizable compound, and is usually centered at 365 nm of a mercury lamp. wavelengths of light are used.
  • the illuminance is preferably in the range of 0.01 mW/cm 2 to 100 mW/cm 2 , more preferably 0.1 mW/cm 2 to 20 mW/cm 2 .
  • the illuminance is less than 0.01 mW/cm 2 , it takes a long time for curing, resulting in poor production efficiency. , the desired optical characteristics cannot be exhibited.
  • the light irradiation time is not particularly limited, it is preferably 10 seconds to 180 seconds, more preferably 30 seconds to 120 seconds.
  • the anisotropic light-diffusing film according to the present invention can be obtained by irradiating light from two directions.
  • the anisotropic light diffusion film is obtained by forming a specific internal structure in the uncured resin composition layer by irradiating the film with low-intensity light for a relatively long time. Therefore, such light irradiation alone may leave unreacted monomer components, causing stickiness and problems in handleability and durability.
  • the residual monomer can be polymerized by additionally irradiating light with a high illuminance of 1000 mW/cm 2 or more. At this time, light irradiation may be performed from the side opposite to the side on which the mask is laminated.
  • the scattering center axis of the resulting anisotropic light-diffusing film can be set to a desired value by adjusting the angle of light with which the uncured resin composition layer is irradiated.
  • anisotropic Light Diffusion Film is excellent in the effect of improving the viewing angle dependence, it can be applied to all display devices such as liquid crystal display devices, organic EL display devices, and plasma displays.
  • the anisotropic light-diffusing film can be used particularly preferably in TN liquid crystals, which tend to have viewing angle dependency problems.
  • a liquid crystal display device including a liquid crystal layer and an anisotropic light diffusion film.
  • the anisotropic light-diffusing film is provided on the viewing side of the liquid crystal layer.
  • the liquid crystal display device may be of any of the TN system, VA system, IPS system, and the like. More specifically, a general liquid crystal device includes a light source, a polarizing plate, a glass substrate, a transparent electrode film, a liquid crystal layer, a transparent electrode film, a color filter, a glass substrate, and a polarizing plate from the display device toward the viewing side. Although it has a layered structure in which it is laminated in order and further has an appropriate functional layer, the anisotropic light-diffusing film may be provided anywhere on the viewing side of the liquid crystal layer.
  • an organic EL display device including a light emitting layer and an anisotropic light diffusion film.
  • the anisotropic light-diffusing film is provided (stacked) on the viewing side of the light-emitting layer (including the electrode connected to the light-emitting layer).
  • the organic EL display device may be of any type such as a top emission method or a bottom emission method, and in the case of a color organic EL display device, may be of any type such as an RGB coloring method or a color filter method. Also, the organic EL display device may be a multilayered one.
  • Partition walls with a height of 30 ⁇ m or 60 ⁇ m were formed with a curable resin using a dispenser around the entire edge of a 100 ⁇ m-thick PET film (manufactured by Toyobo Co., Ltd., trade name: A4300).
  • a paint containing the following UV-curable photopolymerizable compound was dripped into this and covered with another PET film.
  • ⁇ Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5890) 20 parts by weight (manufactured by RAHN, trade name: 00-225/TM18) ⁇ Neopentyl glycol diacrylate (refractive index: 1.450) 30 parts by weight (manufactured by Daicel Cytec, trade name Ebecryl145) ⁇ EO adduct diacrylate of bisphenol A (refractive index: 1.536) 15 parts by weight (manufactured by Daicel Cytec, trade name Ebecryl150) ⁇ Phenoxyethyl acrylate (refractive index 1.518) 40 parts by weight (Made by Kyoeisha Chemical, trade name: Light Acrylate PO-A) ⁇ 2,2-dimethoxy-1,2-diphenylethan-1-one 4 parts by weight (manufactured by BASF, trade name: Irgacure651)
  • a liquid film having a thickness of 60 ⁇ m sandwiched between PET films on both sides was irradiated with an intensity of 10 mW/cm 2 to 100 mW/ from an epi-illumination unit of a UV spot light source (manufactured by Hamamatsu Photonics, trade name: L2859-01).
  • Ultraviolet rays which are parallel rays of cm 2 , were irradiated.
  • a prism sheet was placed between the light source and the liquid film to split the parallel rays into two directions, and the parallel rays in the two directions were irradiated at an azimuth angle of 180°.
  • Anisotropic light diffusion films 1 to 5 having two scattering central axes and having the characteristics shown in Table 1 were obtained by changing parameters such as liquid film thickness, UV illuminance, and liquid film temperature during parallel light irradiation.
  • the two scattering central axes are located on the positive side of 0° at the incident light angle at which the light diffusion is approximately symmetrical when an optical profile is created by measuring the amount of linearly transmitted light (details of measurement will be described later).
  • the angle (the angle of the central portion (central portion of the diffusion region) sandwiched between the linear transmittance minimum values) is obtained as the scattering central axis angle ⁇ A of the scattering central axis A, and is on the minus side of 0°
  • the angle at which it lies was taken as the scattering central axis angle ⁇ B of the scattering central axis B.
  • the obtained azimuth angle of each anisotropic light diffusion film was determined by measuring the amount of linearly transmitted light. In the arrangement shown in FIG. From the arrangement of FIG. 6, each anisotropic light diffusion film is rotated (rotated so that the circular double-headed arrow indicating rotation in FIG. 6 is vertical, but the straight line V remains as it is), and the optical profile for each rotation angle is obtained.
  • the azimuth angle ⁇ B of the scattering central axis B is all 180. ° was This coincided with the azimuth angle of parallel rays in two directions.
  • the side of the produced anisotropic light-diffusing film irradiated with light is hereinafter referred to as the "irradiated surface", and the opposite side is referred to as the "rear surface”.
  • Anisotropic light diffusion films 6 to 8 having one scattering central axis and having the characteristics shown in Table 1 were obtained by changing parameters such as the irradiation angle, liquid film thickness, UV illuminance, and liquid film temperature during parallel light irradiation. .
  • the exposed surface of the anisotropic light-diffusing film constituting the produced anisotropic light-diffusing film laminate is referred to as the "laminate surface”
  • the anisotropic light diffusion constituting the anisotropic light-diffusing film laminate is hereinafter referred to as the "laminate surface”.
  • the back side, which is the exposed surface of the film, is referred to as the "back side of the laminate”.
  • the scattering central axis of the anisotropic light-diffusing film having the surface of the laminate is the scattering central axis A and has the scattering central axis angle ⁇ A
  • the scattering central axis of the anisotropic light-diffusing film having the back surface of the laminate was assumed to be the scattering central axis B and to have the scattering central axis angle ⁇ B .
  • the anisotropic light-diffusing films 7 and 8 were produced in the same manner as the anisotropic light-diffusing film laminate 1 using the anisotropic light-diffusing film 7 to obtain anisotropic light-diffusing film laminates 2 and 3, respectively. It is shown in Table 1, including the characteristics.
  • the anisotropic light-diffusing films and the anisotropic light-diffusing film laminates obtained in Examples were measured using a micrometer (manufactured by Mitutoyo Corporation). The measured value is the average value of the values measured at a total of 5 points including the vicinity of 4 corners on the plane of the produced anisotropic light diffusion film and the anisotropic light diffusion film laminate and 1 point near the center of the plane. did.
  • the anisotropic light diffusion film obtained in the example and the The linear transmitted light amount of the anisotropic light diffusion film laminate was measured.
  • a detector was fixed at a position where it received rectilinear light from the light source, and the anisotropic light-diffusing film and the anisotropic light-diffusing film laminate obtained in Examples were set on a sample holder therebetween.
  • the straight line V was arranged so as to be a line on the anisotropic light diffusion film perpendicular to the tilt direction of the central axis of scattering.
  • the incident side of the light from the light source is the irradiation surface side in the anisotropic light diffusion film, the laminate surface side in the anisotropic light diffusion film laminate, and the scattering center axis angle ⁇ of the anisotropic light diffusion film having the laminate surface. It was set so that A was a positive value. As shown in FIG. 6, the sample is rotated with the straight line V as the axis of rotation, the amount of linear transmitted light corresponding to each incident light angle is measured, the linear transmittance is calculated, the linear transmittance is plotted for each angle, An optical profile was created. With this evaluation method, it is possible to evaluate in which range of angles the incident light is diffused.
  • the amount of linearly transmitted light was measured at a wavelength in the visible light region using a visibility filter. Based on the optical profile obtained as a result of the above measurements, the maximum linear transmittance, which is the maximum value of the linear transmittance, and the incident light angle at the maximum linear transmittance were obtained.
  • the incident light angle at which the light diffusion property is approximately symmetrical is an angle located on the positive side of 0° (between the minimum values of linear transmittance
  • the angle of the central portion (the central portion of the diffusion region)) is obtained as the scattering central axis angle ⁇ A of the scattering central axis A, and the angle located on the minus side of 0° (between the minimum values of the linear transmittance)
  • the angle of the approximate central portion (the central portion of the diffusion region)) was obtained as the scattering central axis angle ⁇ B of the scattering central axis B.
  • the angle of incident light (substantially central portion sandwiched between the minimum values of linear transmittance (central portion of the diffusion region) at which the light diffusion property has approximately symmetry angle) was obtained as the scattering central axis angle ⁇ A of the scattering central axis A.
  • the minimum linear transmittance at the angle between the scattering central axis A and the plane normal of the anisotropic light diffusing film is Tmin A
  • Tmin A the minimum linear transmittance at the angle between the scattering central axis and the plane normal of the anisotropic light-diffusing film was obtained as Tmin A.
  • a plurality of columnar structures of the anisotropic light-diffusing film and the anisotropic light-diffusing film laminate obtained in Examples were observed with an optical microscope for cross sections perpendicular to the columnar axis (irradiation light side during ultraviolet irradiation).
  • a major axis LA and a minor axis SA of the columnar structure were measured.
  • An average value of 20 arbitrary columnar structures was used to calculate the average major axis LA and average minor axis SA.
  • the average major axis LA/average minor axis SA was calculated as an aspect ratio with respect to the obtained average major axis LA and average minor axis SA.
  • ⁇ Haze value (Hz)> Using a haze meter NDH-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), the haze values of the anisotropic light diffusion films and anisotropic light diffusion film laminates obtained in Examples were measured according to JIS K7136-1:2000. rice field. The incident side of light was the irradiated surface for the anisotropic light diffusion film, and the surface of the laminate for the anisotropic light diffusion film laminate.
  • anisotropic light-diffusing films 1 to 5 and the anisotropic light-diffusing film laminates 1 to 3 prepared in Examples were used as the anisotropic light-diffusing films 1 to 5 of Examples 1 to 5 and the anisotropic light diffusion films 1 to 5 of Comparative Examples 1 to 3 shown in Table 2.
  • Anisotropic light diffusion film laminates 1 to 3 were evaluated as follows.
  • white luminance was measured in a polar angle range of 0 to 80° with respect to the normal direction of the liquid crystal display when white was displayed on the liquid crystal display.
  • the white luminance ratio was calculated as a ratio to a blank, with 1 being the state in which the anisotropic light-diffusing film or the anisotropic light-diffusing film laminate was not attached to the surface of the liquid crystal display.
  • ⁇ bokeh> In the configuration used for the evaluation of white luminance (an anisotropic light diffusion film or an anisotropic light diffusion film laminate was attached to the surface of the liquid crystal display), white was displayed on the liquid crystal display, and RGB pixels were confirmed from the surface using a loupe. .
  • RGB can be identified respectively: ⁇ At least part of RGB looks mixed: ⁇

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Abstract

The present invention provides an anisotropic light-diffusing film that has the effect of suppressing blurring and increasing the viewing angle in two azimuths that are vertically or horizontally isosymmetric while suppressing thickness and costs. This anisotropic light-diffusing film has a matrix region and a column-shaped region constituted of a plurality of column-shaped structures having a different diffraction index from the matrix region, the diffusion changing via the incidence angle of light, wherein: a scattering central axis A and a scattering central axis B are included within an angle range of more than 0° and less than 90° when the angle of the normal of the anisotropic light-diffusing film is set to 0°; an azimuth angle φB of the scattering central axis B is 170° to 190° when an azimuth angle φA of the scattering central axis A is set to 0°; and θＢ＝θA±10° when the angle between the normal and the scattering central axis A is set to a scattering central axis angle θA and the angle between the normal and the scattering central axis B is set to a scattering central axis angle θB.

Description

異方性光拡散フィルムおよび表示装置Anisotropic light diffusion film and display device
　本発明は、異方性光拡散フィルムおよび異方性光拡散フィルムを備えた表示装置に関する。 The present invention relates to an anisotropic light-diffusing film and a display device equipped with the anisotropic light-diffusing film.
　表示装置において「視野角」は重要な特性の一つであり、覗き見防止等の用途を除けば、視野角は広いことが好ましいと一般的に考えられている。最も代表的な表示装置の一つであるＬＣＤの、視野角拡大方法は、大きく２つに大別することができる。
　１つ目は、ＴＮ、ＶＡ、ＩＰＳといった液晶パネルの駆動方式や、光学補償用目的での位相差フィルムの使用等の「液晶パネルの内部設計による方法」である。
　２つ目は、特定の液晶パネル視認側表面へ拡散フィルムを使用する等の「液晶パネル表面への部材追加による方法」である。 A "viewing angle" is one of the important characteristics of a display device, and it is generally considered that a wide viewing angle is preferable, except for applications such as prevention of prying eyes. Methods for expanding the viewing angle of LCDs, which are one of the most typical display devices, can be broadly classified into two.
The first one is a liquid crystal panel driving method such as TN, VA, or IPS, or a “method based on the internal design of the liquid crystal panel” such as the use of a retardation film for the purpose of optical compensation.
The second is a "method of adding members to the surface of a liquid crystal panel" such as using a diffusion film on the surface of a specific liquid crystal panel on the viewing side.
　「液晶パネルの内部設計による方法」が基本方法ではあるが、個別の用途や使用環境毎に最適化する為には、「液晶パネル表面への部材追加による方法」の方法が、生産性の面で有利である。 "Method by internal design of liquid crystal panel" is the basic method, but in order to optimize for each individual application and usage environment, "Method by adding materials to the surface of liquid crystal panel" is more productive. is advantageous.
　「液晶パネル表面への部材追加による方法」の具体例としては、例えば、（１）特許文献１に示す様な透光性微粒子が分散された光拡散層を有する光拡散フィルム等の「等方性拡散体」を使用する方法、（２）特許文献２および３に示す様なマイクロレンズアレイや、ウェーブレンズフィルム等の「レンズ類」を液晶パネル表面に配置する方法、（３）特許文献４に示す様な、「角度依存性を有する光制御フィルム」を設けることで視野角特性を向上させる方法、等がある。 As a specific example of the "method by adding members to the surface of the liquid crystal panel", for example, (1) an "isotropic method" such as a light diffusion film having a light diffusion layer in which translucent fine particles are dispersed as shown in Patent Document 1 (2) A method of arranging a microlens array as shown in Patent Documents 2 and 3 or a "lens" such as a wave lens film on the liquid crystal panel surface; (3) Patent Document 4 There is a method of improving viewing angle characteristics by providing a "light control film having angle dependence" as shown in .
　「角度依存性を有する光制御フィルム」としては、入射光の入射角度に応じて直線透過光量を変化させることが可能な「異方性および指向性を有する異方性光拡散フィルム」が、特定方位への視野角拡大ができ、光の配向も急峻ではなく、他の部材とも貼り合せが容易である為、表示装置等で活用されている。 As a "light control film with angle dependence", an "anisotropic light diffusion film with anisotropy and directivity" that can change the amount of linearly transmitted light according to the incident angle of incident light can be used in a specific direction. The viewing angle can be widened, the orientation of light is not steep, and it is easy to bond with other members.
　特許文献５では、光の拡散と透過に入射角依存性を有し、同一フィルム内に２つの構造領域を有することで、光拡散角度領域を効果的に拡大できる単一層からなる光拡散フィルムが開示されている。 In Patent Document 5, a light diffusion film consisting of a single layer that has incident angle dependence in light diffusion and transmission and has two structural regions in the same film can effectively expand the light diffusion angle region. disclosed.
特開２０１２－９８５２６号公報JP 2012-98526 A 特開平８－１６６５８２号公報JP-A-8-166582 特開平７－２３９４６７号公報JP-A-7-239467 特開平７－１４６４０４号公報JP-A-7-146404 国際公開ＷＯ２０１４／１５６４２０International publication WO2014/156420
　特許文献１の「等方性拡散体」は、全ての方位に視野角拡大効果を生じさせる為、特定の方位へ視野角を拡大させたい場合であっても、該特定方位外へも拡散させてしまい、視野角を拡大させたい方位での輝度を低下させにくいという問題があった。 The "isotropic diffuser" of Patent Document 1 produces a viewing angle widening effect in all directions, so even if it is desired to expand the viewing angle in a specific direction, the diffuser is also diffused outside the specific direction. As a result, there is a problem that it is difficult to reduce the luminance in the direction in which the viewing angle is desired to be widened.
　特許文献２および３の「レンズ類」は、光の屈折や反射を利用しているので光の配向が急峻となり、視野角の変化による明るさが急変しやすいことや、その配列やパターン構造による干渉の為、ギラツキやモアレが発生しやすいという問題があった。加えて、レンズの凹凸構造が最表面にある場合、汚れ等の付着により効果が低減しやすいという問題があった。更に、凹凸構造を保護する為に別のフィルム等の貼り合せを検討する場合、粘着層による貼り付けでは、粘着層により凹凸が埋まり、光学特性が変化してしまう問題が生じ、粘着層を使用しなかったとしても、凹凸構造とフィルム間に空気層が存在する等して、透過率が低下してしまう問題があった。 The "lenses" of Patent Documents 2 and 3 use light refraction and reflection, so the light orientation becomes steep, and the brightness tends to change suddenly due to changes in the viewing angle. Because of the interference, glare and moiré tend to occur. In addition, when the concave-convex structure of the lens is on the outermost surface, there is a problem that the effect tends to be reduced due to adhesion of dirt or the like. Furthermore, when considering attaching another film or the like to protect the uneven structure, attaching with an adhesive layer causes a problem that the unevenness is filled with the adhesive layer and the optical characteristics change, so the adhesive layer is used. Even if this is not done, there is a problem that the transmittance is lowered due to the presence of an air layer between the uneven structure and the film.
　特許文献４の「角度依存性を有する光制御フィルム」は、光の入射角に対するヘイズ率の変化が急峻なので、視野角変化による明るさ変化が急激になる問題があった。 The "light control film having angle dependence" of Patent Document 4 has a steep change in the haze ratio with respect to the incident angle of light, so there is a problem that the brightness changes sharply due to the change in the viewing angle.
　特許文献５の「光拡散フィルム」は、例えばＴＶやデジタルサイネージ等の用途では、上下の深い角度から見ることはあまり無い為、主に左右の２方位への視野角拡大が求められるが、左右２方位に視野角を拡大させたい場合、厚み方向に段階的に拡散することで、左右バランス良く視野角を拡大させることが困難なだけでなく、光拡散フィルムの構造上、厚みが増えてしまうことやコストがかかってしまうという問題があった。 The "light diffusion film" of Patent Document 5, for example, in applications such as TV and digital signage, is rarely viewed from a deep vertical angle. If you want to expand the viewing angle in two directions, it is not only difficult to expand the viewing angle with good left-right balance by diffusing in the thickness direction in stages, but also the thickness increases due to the structure of the light diffusion film. There was a problem that it took a lot of work and cost.
　そこで本発明は、厚みやコストを抑えながら、上下又は左右等対称性を有する２方位への視野角拡大およびボケ抑制を可能とする異方性光拡散フィルムを提供することを課題とする。 Therefore, an object of the present invention is to provide an anisotropic light diffusion film that enables widening of the viewing angle in two directions having vertical or horizontal symmetry and suppression of blurring while suppressing thickness and cost.
　特定の性質を有する異方性光拡散フィルムとすることで、上記課題を解決可能なことを見出し、本発明を完成させた。即ち、本発明は以下の通りである。 We have found that the above problems can be solved by making an anisotropic light diffusion film with specific properties, and have completed the present invention. That is, the present invention is as follows.
　本発明は、
　光の入射角度により拡散性が変化する異方性光拡散フィルムであって、
　前記異方性光拡散フィルムは、マトリックス領域と、前記マトリックス領域とは屈折率の異なる複数の柱状構造体である柱状領域とを有し、
　前記異方性光拡散フィルムの法線角度を０°としたとき、０°超９０°未満の角度範囲に散乱中心軸Ａおよび散乱中心軸Ｂを有し、
　前記散乱中心軸Ａの方位角φＡを０°としたとき、前記散乱中心軸Ｂの方位角φBは、１７０°～１９０°であり、
　前記法線と、前記散乱中心軸Ａとのなす角度を散乱中心軸角度θＡとし、前記法線と前記散乱中心軸Ｂとのなす角度を散乱中心軸角度θＢとすると、θＢ＝θＡ±１０°であることを特徴とする、異方性光拡散フィルムである。 The present invention
An anisotropic light diffusion film whose diffusibility changes depending on the incident angle of light,
The anisotropic light diffusion film has a matrix region and a columnar region that is a plurality of columnar structures having a different refractive index from the matrix region,
When the normal angle of the anisotropic light diffusion film is 0°, the scattering central axis A and the scattering central axis B are in an angle range of more than 0° and less than 90°,
When the azimuth angle φ A of the scattering central axis A is 0°, the azimuth angle φ B of the scattering central axis B is 170° to 190°,
Let the angle formed by the normal line and the scattering center axis A be the scattering center axis angle θ A , and let the angle between the normal line and the scattering center axis B be the scattering center axis angle θ B , then θ B =θ An anisotropic light-diffusing film characterized in that A is ±10°.
　前記散乱中心軸Ａと法線との間の角度における極小直線透過率をＴｍｉｎＡとし、前記散乱中心軸Ｂと法線との間の角度における極小直線透過率をＴｍｉｎＢとすると、
｜ＴｍｉｎＡ－ＴｍｉｎＢ｜≦５パーセントポイント
であることが好ましい。
　前記散乱中心軸角度θＡが１０°～６０°であることが好ましい。
　ヘイズ値が、４０％以上であることが好ましい。
　前記複数の柱状構造体の配向方向に垂直な断面における短径と長径のアスペクト比が２未満であることが好ましい。 Let Tmin A be the minimum linear transmittance at the angle between the scattering central axis A and the normal, and Tmin B be the minimum linear transmittance at the angle between the scattering central axis B and the normal.
|Tmin A −Tmin B |≦5 percentage points is preferred.
The scattering central axis angle θ A is preferably 10° to 60°.
It is preferable that the haze value is 40% or more.
It is preferable that the aspect ratio of the minor axis to the major axis in the cross section perpendicular to the alignment direction of the plurality of columnar structures is less than 2.
　また、本発明は、
　前記異方性光拡散フィルムを含むことを特徴とする、表示装置である。 In addition, the present invention
A display device comprising the anisotropic light diffusion film.
　本発明によれば、厚みやコストを抑えながら、上下又は左右等対称性を有する２方位への視野角拡大およびボケ抑制効果を有する異方性光拡散フィルムを提供可能である。 According to the present invention, it is possible to provide an anisotropic light diffusion film that has an enlarged viewing angle in two directions with vertical or horizontal symmetry and an effect of suppressing blurring, while suppressing thickness and costs.
異方性光拡散フィルムの入射光角度依存性を示した説明図である。FIG. 4 is an explanatory diagram showing the incident light angle dependency of an anisotropic light diffusion film. 異方性光拡散フィルムの表面構造を示す上面図である。FIG. 3 is a top view showing the surface structure of an anisotropic light-diffusing film; 異方性光拡散フィルムの例を示す模式図である。It is a schematic diagram which shows the example of an anisotropic light-diffusion film. 異方性光拡散フィルムにおける散乱中心軸を説明するための３次元極座標表示である。It is a three-dimensional polar coordinate representation for explaining the scattering central axis in an anisotropic light diffusion film. 異方性光拡散フィルムにおける光学プロファイルの一例を示すグラフである。4 is a graph showing an example of an optical profile in an anisotropic light diffusion film; 異方性光拡散フィルムの直線透過光量の測定方法を示す模式図である。It is a schematic diagram which shows the measuring method of the linear transmission light amount of an anisotropic light-diffusion film. 異方性光拡散フィルムにおける散乱中心軸Ａと散乱中心軸Ｂとの関係を示す模式図である。FIG. 3 is a schematic diagram showing the relationship between the central scattering axis A and the central scattering axis B in an anisotropic light diffusion film. 任意工程１－３による本発明の異方性光拡散フィルムの製造方法を示す模式図である。FIG. 2 is a schematic diagram showing a method for producing an anisotropic light-diffusing film of the present invention by optional step 1-3.
　以下、一般的な異方性光拡散フィルム（散乱中心軸角度を１つのみ有する異方性光拡散フィルム）の構造等について説明する。
　次いで、本発明に係る異方性光拡散フィルム（散乱中心軸角度を２つ有する異方性光拡散フィルム）の構造、物性、製造方法、用途等について説明する。 The structure and the like of a general anisotropic light-diffusing film (an anisotropic light-diffusing film having only one scattering central axis angle) will be described below.
Next, the structure, physical properties, manufacturing method, application, etc. of the anisotropic light-diffusing film (anisotropic light-diffusing film having two scattering central axis angles) according to the present invention will be described.
＜＜＜＜１　一般的な異方性光拡散フィルム＞＞＞＞
　異方性光拡散フィルムとは、光の入射角により、直線透過率［（入射した光の直線方向の透過光量）／（入射した光の光量）］が変化する、光学異方性を有するフィルムである。即ち、異方性光拡散フィルムに対する入射光について、所定の角度範囲の入射光は直線性を維持して透過し、その他の角度範囲の入射光は、拡散性を示す。 <<<<1 General anisotropic light diffusion film>>>>
The anisotropic light diffusion film is a film having optical anisotropy, in which the linear transmittance [(amount of transmitted light in the linear direction of incident light)/(amount of incident light)] changes depending on the angle of incidence of light. . That is, with respect to incident light to the anisotropic light diffusion film, incident light within a predetermined angle range is transmitted while maintaining linearity, and incident light within other angle ranges exhibits diffusing properties.
　例えば、図１に示される一例である異方性光拡散フィルムでは、入射角が２０°～５０°の場合に拡散性を示し、その他の入射角では拡散性を示さず、直線透過性を示す。 For example, the anisotropic light diffusion film, which is an example shown in FIG. 1, exhibits diffusibility when the incident angle is 20° to 50°, and exhibits no diffusivity at other incident angles and exhibits linear transmittance.
　異方性光拡散フィルムは、マトリックス領域と、マトリックス領域とは屈折率の異なる複数の柱状構造体である柱状領域とを有する。また、異方性光拡散フィルムに含まれる複数の柱状構造体は、通常、異方性光拡散フィルムの一方の表面から他方の表面にかけて配向、かつ、延在して構成されている（図３参照）。 The anisotropic light diffusion film has a matrix region and columnar regions, which are a plurality of columnar structures having different refractive indices from those of the matrix region. In addition, the plurality of columnar structures contained in the anisotropic light-diffusing film are usually oriented and extended from one surface to the other surface of the anisotropic light-diffusing film (see FIG. 3).
　柱状構造体の長さは、特に限定されず、異方性光拡散フィルムの一方の表面から他方の表面に貫通したものでもよく、一方の表面から他方の表面に届かない長さでも良い。 The length of the columnar structure is not particularly limited, and may be a length that penetrates from one surface of the anisotropic light diffusion film to the other surface, or a length that does not reach from one surface to the other surface.
　異方性光拡散フィルムに含まれる複数の柱状構造体の、柱軸に垂直な断面の形状は、短径と、長径とを有する形状とすることができる。 The shape of the cross section perpendicular to the column axis of the plurality of columnar structures included in the anisotropic light diffusion film can be a shape having a minor axis and a major axis.
　柱状構造体の断面形状は、特に限定されず、例えば、円形、楕円形、多角形とすることができる。円形の場合には、短径と長径とは等しくなり、楕円形の場合には、短径は短軸の長さ、長径は長軸の長さであり、多角形の場合には、多角形内の最も短い長さを短径とし、最も長い長さを長径とすることができる。図２に、異方性光拡散フィルムの表面方向から見た複数の柱状構造体を示す。図２中、ＬＡは長径を表わし、ＳＡは短径を表わしている。 The cross-sectional shape of the columnar structure is not particularly limited, and may be circular, elliptical, or polygonal, for example. In the case of a circle, the minor axis and the major axis are equal; in the case of an ellipse, the minor axis is the length of the minor axis and the major axis is the length of the major axis; The shortest length can be used as the short axis, and the longest length can be used as the long axis. FIG. 2 shows a plurality of columnar structures viewed from the surface direction of the anisotropic light diffusion film. In FIG. 2, LA represents the major axis and SA represents the minor axis.
　図２（ａ）は、柱状構造体のアスペクト比が２～２０の異方性光拡散フィルムの一例を示している。
　また、図２（ｂ）は、柱状構造体のアスペクト比が1以上２未満の異方性光拡散フィルムの一例を示しており、アスペクト比が１の場合、ＬＡ＝ＳＡとなる。 FIG. 2(a) shows an example of an anisotropic light diffusion film in which the aspect ratio of the columnar structure is 2-20.
Further, FIG. 2(b) shows an example of an anisotropic light diffusion film in which the aspect ratio of the columnar structures is 1 or more and less than 2. When the aspect ratio is 1, LA=SA.
　アスペクト比が１以上２未満の場合には、柱状構造体の軸方向に平行な光を照射した場合、その透過光は等方的に拡散する｛図３（ａ）を参照｝。一方、アスペクト比が２～２０の場合には、同様に軸方向に平行な光を照射した場合には、アスペクト比に応じた異方性をもって拡散する｛図３（ｂ）を参照｝。 When the aspect ratio is 1 or more and less than 2, when light parallel to the axial direction of the columnar structure is irradiated, the transmitted light diffuses isotropically {see FIG. 3(a)}. On the other hand, when the aspect ratio is 2 to 20, similarly, when the light parallel to the axial direction is irradiated, diffusion occurs with an anisotropy corresponding to the aspect ratio {see FIG. 3(b)}.
　柱状構造体の短径および長径は、異方性光拡散フィルムの、柱軸に垂直な断面を光学顕微鏡で観察し、任意に選択した２０個の柱状構造体についてそれぞれの短径、長径を計測し、これらの平均値とすることができる。 The minor axis and major axis of the columnar structures were obtained by observing a cross section of the anisotropic light diffusion film perpendicular to the columnar axis with an optical microscope, and measuring the minor axis and major axis of each of 20 arbitrarily selected columnar structures. These average values can be used.
　ここで、屈折率が異なるとは、異方性光拡散フィルムに入射した光の少なくとも一部が、マトリックス領域と、柱状領域との界面において反射が起こる程度に差異があればよく、特に限定されないが、例えば、マトリックス領域と柱状領域との屈折率の差は、０．００１以上あればよい。 Here, the difference in refractive index means that at least part of the light incident on the anisotropic light-diffusing film is reflected at the interface between the matrix region and the columnar region, and is not particularly limited. For example, the difference in refractive index between the matrix region and the columnar region should be 0.001 or more.
　柱状領域の、異方性光拡散フィルムの法線方向に対する傾斜角度を調整することで、後述する散乱中心軸角度を調整することができる。 By adjusting the inclination angle of the columnar region with respect to the normal direction of the anisotropic light diffusion film, it is possible to adjust the scattering center axis angle, which will be described later.
＜＜＜１－１　散乱中心軸＞＞＞
　散乱中心軸を有する異方性光拡散フィルムにおいて、散乱中心軸と複数の柱状構造体の配向方向（延在方向）とは、通常、平行な関係にある。なお、散乱中心軸と複数の柱状構造体の配向方向とが平行であるとは、屈折率の法則（Ｓｎｅｌｌの法則）を満たすものであればよく、厳密に平行である必要はない。 <<<1-1 Scattering central axis>>>
In an anisotropic light-diffusing film having a central scattering axis, the central scattering axis and the alignment direction (extending direction) of the plurality of columnar structures are generally parallel to each other. It should be noted that the scattering center axis and the orientation direction of the plurality of columnar structures being parallel only need to satisfy the refractive index law (Snell's law), and need not be strictly parallel.
　Ｓｎｅｌｌの法則は、屈折率ｎ１の媒質から屈折率ｎ２の媒質の界面に対して光が入射する場合、その入射光角度θ１と屈折角θ２との間に、ｎ１ｓｉｎθ１＝ｎ２ｓｉｎθ２の関係が成立するものである。例えば、ｎ１＝１（空気）、ｎ２＝１．５１（異方性光拡散フィルム）とすると、入射光角度が３０°の場合、柱状領域の配向方向（屈折角）は約１９°となるが、このように入射光角度と屈折角が異なっていてもＳｎｅｌｌの法則を満たしていれば、本発明においては平行の概念に包含される。 According to Snell's law, when light is incident from a medium with a refractive index n1 to an interface of a medium with a refractive index n2, n 1 sin θ 1 =n 2 sin θ 2 between the incident light angle θ1 and the refraction angle θ2. relationship is established. For example, when n 1 =1 (air) and n 2 =1.51 (anisotropic light diffusion film), when the incident light angle is 30°, the orientation direction (refractive angle) of the columnar regions is about 19°. In the present invention, even if the incident light angle and the refraction angle are different from each other, if Snell's law is satisfied, the concept of parallelism is included in the present invention.
　次に、図４を参照しながら、異方性光拡散フィルムにおける散乱中心軸Ｐについてより詳細に説明する。図４は、異方性光拡散フィルムにおける散乱中心軸Ｐを説明するための３次元極座標表示である。 Next, the scattering center axis P in the anisotropic light diffusion film will be described in more detail with reference to FIG. FIG. 4 is a three-dimensional polar coordinate representation for explaining the scattering center axis P in the anisotropic light diffusion film.
　散乱中心軸は、異方性光拡散フィルムへの入射光角度を変化させた際に光拡散性がその入射光角度を境に略対称性を有する光の入射光角度と一致する方向を意味する。なお、このときの入射光角度は、異方性光拡散フィルムの直線透過光量を測定し、算出した直線透過率を入射光角度毎にプロットしたものである光学プロファイル（一例として図５）における直線透過率極小値間に挟まれた略中央部（拡散領域の中央部）の角度となる。 The scattering central axis means the direction in which the light diffusibility coincides with the incident light angle of light having approximately symmetry with respect to the incident light angle when the incident light angle to the anisotropic light diffusion film is changed. The incident light angle at this time is the linear transmittance in the optical profile (FIG. 5 as an example) obtained by measuring the linear transmission light amount of the anisotropic light diffusion film and plotting the calculated linear transmittance for each incident light angle. It is the angle of the approximate central portion (the central portion of the diffusion region) sandwiched between the minimum values.
　散乱中心軸は、図４に示すような３次元極座標表示によれば、異方性光拡散フィルムの表面をｘｙ平面とし、異方性光拡散フィルムの表面に対する法線をｚ軸とすると、極角θと方位角φとによって表現することができる。 According to the three-dimensional polar coordinate representation as shown in FIG. 4, the scattering center axis is the polar angle θ and the azimuth when the surface of the anisotropic light diffusion film is the xy plane and the normal line to the surface of the anisotropic light diffusion film is the z axis. can be expressed by the angle φ
　ここで、異方性光拡散フィルムの法線（図４に示すｚ軸）と、柱状領域とのなす極角θ（０°≦θ＜９０°）を散乱中心軸角度と定義することができる。未硬化樹脂組成物層を光硬化させ柱状領域を形成させる工程において、照射する光線の方向を変えることで、複数の柱状構造体の軸方向の角度を所望の範囲に調整することができる。 Here, the polar angle θ (0°≦θ<90°) formed by the normal to the anisotropic light diffusion film (z-axis shown in FIG. 4) and the columnar region can be defined as the scattering central axis angle. In the step of photocuring the uncured resin composition layer to form the columnar regions, the angle of the axial direction of the plurality of columnar structures can be adjusted within a desired range by changing the direction of the irradiated light beam.
＜＜＜１－２　光学プロファイル＞＞＞
　図５に示すように、異方性光拡散フィルムは、入射光角度によって直線透過率が変化する光拡散性の入射光角度依存性を有するものである。ここで、図５のように光拡散性の入射光角度依存性を示す曲線を以下、「光学プロファイル」と称する。 <<<1-2 Optical Profile>>>
As shown in FIG. 5, the anisotropic light diffusing film has light diffusing properties dependent on the incident light angle, in which the linear transmittance changes depending on the incident light angle. Here, the curve showing the incident light angle dependence of light diffusion as shown in FIG. 5 is hereinafter referred to as an "optical profile".
　光学プロファイルは、例えば以下のようにして作成できる。 An optical profile can be created, for example, as follows.
　図６に示すように、異方性光拡散フィルムを光源１と検出器２との間に配置する。本形態においては、光源１からの照射光Ｉが、異方性光拡散フィルムの法線方向から入射する場合を入射光角度０°とした。また、異方性光拡散フィルムは直線Ｖを回転軸として、任意に回転させることができるように配置され、光源１および検出器２は固定されている。すなわち、この方法によれば、光源１と検出器２との間にサンプル（異方性光拡散フィルム）を配置し、サンプル表面の直線Ｖを回転軸として角度を変化させながらサンプルを直進透過して検出器２に入る直線透過光量を測定する（この直線Ｖは、散乱中心軸の傾斜方位に垂直な異方性光拡散フィルム上の線である）。その後、この直線透過光量より直線透過率を算出して、直線透過率を角度ごとにプロットし、光学プロファイルを作成する。 An anisotropic light diffusion film is placed between the light source 1 and the detector 2, as shown in FIG. In this embodiment, the incident light angle is 0° when the irradiation light I from the light source 1 is incident from the normal direction of the anisotropic light diffusion film. Further, the anisotropic light diffusion film is arranged so as to be freely rotatable with the straight line V as the axis of rotation, and the light source 1 and the detector 2 are fixed. That is, according to this method, a sample (anisotropic light diffusion film) is placed between the light source 1 and the detector 2, and the sample is transmitted straight through while changing the angle with the straight line V on the sample surface as the axis of rotation for detection. The linear transmitted light amount entering the device 2 is measured (this straight line V is a line on the anisotropic light diffusion film perpendicular to the tilted azimuth of the central axis of scattering). After that, the linear transmittance is calculated from the amount of linearly transmitted light, and the linear transmittance is plotted for each angle to create an optical profile.
　光学プロファイルは、光拡散性を直接的に表現しているものではないが、直線透過率が低下することで、逆に拡散透過率が増大していると解釈すれば、概ね光拡散性を示しているといえる。 The optical profile does not directly express the light diffusibility, but if it is interpreted that the diffuse transmittance increases due to the decrease in the in-line transmittance, it generally indicates the light diffusivity. It can be said that
　通常の等方的な光拡散フィルムでは、０°付近の入射光角度をピークとする、山型の光学プロファイルを示す。 A normal isotropic light diffusion film exhibits a mountain-shaped optical profile with a peak at an incident light angle near 0°.
　異方性光拡散フィルムでは、例えば、散乱中心軸角度を０°とすると（図５）、０°付近の入射光角度で直線透過率が小さく、入射光角度（の絶対値）が大きくなるにつれて直線透過率が大きくなる谷型の光学プロファイルを示す。 In an anisotropic light diffusion film, for example, if the scattering central axis angle is 0° (Fig. 5), the linear transmittance is small at an incident light angle near 0°, and the linear transmittance decreases as the incident light angle (absolute value) increases. Figure 3 shows a valley-shaped optical profile with increasing index.
　このように、異方性光拡散フィルムは、入射光が散乱中心軸に近い入射光角度範囲では強く拡散されるが、それ以上の入射光角度範囲では拡散が弱まり直線透過率が高まるという性質を有する。 In this way, the anisotropic light diffusion film has the property that the incident light is strongly diffused in the incident light angle range close to the scattering center axis, but the diffusion weakens and the linear transmittance increases in the incident light angle range beyond that.
　散乱中心軸角度が０°以外の場合には、散乱中心軸角度付近の入射光角度で直線透過率が小さくなるように光学プロファイルが移動する（光学プロファイルの谷部が散乱中心軸角度側に移動する）。 When the scattering center axis angle is other than 0°, the optical profile shifts so that the linear transmittance decreases at incident light angles near the scattering center axis angle (the troughs of the optical profile move to the scattering center axis angle side). do).
＜＜＜１－３　直線透過率＞＞＞
　図５に示すように、直線透過率が最大となる入射角で異方性光拡散フィルムに入射した光の直線透過率を、最大直線透過率と称する。 <<<1-3 Linear transmittance >>>
As shown in FIG. 5, the linear transmittance of light incident on the anisotropic light diffusion film at the incident angle at which the linear transmittance is maximized is referred to as the maximum linear transmittance.
　図５に示すように、直線透過率が最小となる入射角で異方性光拡散フィルムに入射した光の直線透過率を、最小直線透過率と称する。 As shown in FIG. 5, the linear transmittance of light incident on the anisotropic light diffusion film at the incident angle at which the linear transmittance is minimized is called the minimum linear transmittance.
　図５に示すように、最大直線透過率と最小直線透過率との中間値の直線透過率に対する２つの入射光角度の角度範囲を拡散領域（この拡散領域の幅を「拡散幅」）と称し、それを除く入射光角度範囲を非拡散領域（透過領域）と称する。 As shown in FIG. 5, the angle range of the two incident light angles with respect to the intermediate value of the linear transmittance between the maximum linear transmittance and the minimum linear transmittance is called a diffusion region (the width of this diffusion region is the "diffusion width"). , is called a non-diffusion area (transmissive area).
＜＜＜１－４　ヘイズ値＞＞＞
　異方性光拡散フィルムのヘイズ値（全ヘイズ）は、異方性光拡散フィルムの拡散性を示す指標である。ヘイズ値が大きくなると、異方性光拡散フィルムの拡散性が高くなる。 <<<1-4 Haze value>>>
The haze value (total haze) of an anisotropic light-diffusing film is an index showing the diffusibility of the anisotropic light-diffusing film. As the haze value increases, the diffusibility of the anisotropic light-diffusing film increases.
　ヘイズ値の測定方法は、特に限定されず、公知の方法で測定することができる。例えば、ＪＩＳ　Ｋ７１３６－１：２０００「プラスチック－透明材料のヘイズの求め方」によって測定することができる。 A method for measuring the haze value is not particularly limited, and it can be measured by a known method. For example, it can be measured according to JIS K7136-1:2000 "Plastics - Determination of haze of transparent materials".
＜＜＜＜２　本発明に係る異方性光拡散フィルム＞＞＞＞
　以下、本発明に係る異方性光拡散フィルムについて説明する。以下の説明においては、矛盾の存在しない範囲で、前述した一般的な異方性光拡散フィルムで説明された事項を全て適用できるものとする。 <<<<2 Anisotropic Light Diffusion Film According to the Present Invention>>>>
The anisotropic light-diffusing film according to the present invention will be described below. In the following description, it is assumed that all the matters described in the above general anisotropic light diffusion film can be applied as long as there is no contradiction.
＜＜＜２－１　本発明に係る異方性光拡散フィルムの構造＞＞＞
　本発明に係る異方性光拡散フィルムは、１層内に、異方性光拡散フィルムの法線方向に対してある方向に傾斜した複数の柱状構造体からなる第１の柱状領域と、異方性光拡散フィルムの法線方向に対して第１の柱状領域とは別の方向に傾斜した複数の柱状構造体からなり、第１の柱状領域とは延在方向の異なる第２の柱状領域とを有する。 <<<2-1 Structure of anisotropic light diffusion film according to the present invention>>>
The anisotropic light-diffusing film according to the present invention includes, in one layer, a first columnar region composed of a plurality of columnar structures inclined in a certain direction with respect to the normal direction of the anisotropic light-diffusing film, and an anisotropic light-diffusing film. It is composed of a plurality of columnar structures inclined in a different direction from the first columnar regions with respect to the normal direction, and has a second columnar region extending in a different direction from the first columnar regions.
　本発明に係る異方性光拡散フィルムは、このような構成を有するため、第１の柱状領域に基づく第１の散乱中心軸（散乱中心軸Ａ）、および、第２の柱状領域に基づく第２の散乱中心軸（散乱中心軸Ｂ）として、１層内に２つの散乱中心軸を有することとなる（図７（１）参照）。 Since the anisotropic light diffusion film according to the present invention has such a configuration, the first scattering center axis (scattering center axis A) based on the first columnar region and the second scattering center axis based on the second columnar region As the scattering center axis (scattering center axis B), one layer has two scattering center axes (see FIG. 7(1)).
＜＜２－１－１　散乱中心軸Ａおよび散乱中心軸Ｂの位置関係＞＞
　ここで、本発明に係る異方性光拡散フィルムにおいて、第１の柱状領域および第２の柱状領域は、共に、異方性光拡散フィルムの一方の表面から他方の表面にかけて、異方性光拡散フィルムの法線方向に対し、傾斜する構造を有する。従って、「散乱中心軸Ａと散乱中心軸Ｂとの位置関係」と、「散乱中心軸Ｂを異方性光拡散フィルムの法線周りに１８０°回転させた場合の散乱中心軸Ａと散乱中心軸Ｂとの位置関係」とは、異なるものとなる。
　従って、本発明においては、散乱中心軸ＡおよびＢの位置関係は、上述の極角θおよび方位角φによって示されることとなる。 <<2-1-1 Positional Relationship between Scattering Central Axis A and Scattering Central Axis B>>
Here, in the anisotropic light-diffusing film according to the present invention, both the first columnar region and the second columnar region extend from one surface to the other surface of the anisotropic light-diffusing film in the normal direction of the anisotropic light-diffusing film. It has a tilted structure. Therefore, "the positional relationship between the scattering central axis A and the scattering central axis B" and "the scattering central axis A and the scattering central axis B when the scattering central axis B is rotated 180° around the normal line of the anisotropic light diffusion film "positional relationship with" is different.
Therefore, in the present invention, the positional relationship between the scattering central axes A and B is indicated by the above-described polar angle θ and azimuth angle φ.
　図７を参照しながら、散乱中心軸Ａおよび散乱中心軸Ｂの位置関係について具体的に説明する。 The positional relationship between the scattering central axis A and the scattering central axis B will be specifically described with reference to FIG.
　図７（１）に示すように、本発明では、異方性光拡散フィルムの表面に対する法線方向をＺ軸としたとき、散乱中心軸ＡをＸ軸上にあるものとし、その方位角φＡ（図７（１）では３時の方向）を０°とする。 As shown in FIG. 7(1), in the present invention, when the normal direction to the surface of the anisotropic light diffusion film is the Z axis, the scattering center axis A is on the X axis, and its azimuth angle φ A ( The 3 o'clock direction in FIG. 7(1) is assumed to be 0°.
　さらに、図７（２）に示すように、散乱中心軸ＡからＸ－Ｙ平面（異方性光拡散フィルムの表面方向の平面）に投影した線と、散乱中心軸ＢからＸ－Ｙ平面に投影した線と、の成す角度φＢは、１７０°～１９０°であり、より好ましくは、１７５°～１８５°、さらに好ましくは１８０°である（図７（２）は好ましい例を示している）。φＢをこのような範囲とすることで、異方性光拡散フィルムの上下又は左右等対称性を有する２方位への視野角拡大に優れる。 Furthermore, as shown in FIG. 7(2), a line projected from the central scattering axis A onto the XY plane (a plane in the surface direction of the anisotropic light diffusion film) and a line projected from the central scattering axis B onto the XY plane The angle φ B formed with the line is 170° to 190°, preferably 175° to 185°, still more preferably 180° (FIG. 7(2) shows a preferred example). By setting φ B within such a range, the anisotropic light-diffusing film is excellent in widening the viewing angle in two azimuths having vertical or horizontal symmetry.
　本発明に係る異方性光拡散フィルムは、異方性光拡散フィルムの法線方向の角度を０°としたとき、０°超９０°未満（好ましくは１０°～６０°、より好ましくは２０°～４５°）の角度範囲に２つの散乱中心軸を有する。即ち、図７（３）に示すように、異方性光拡散フィルムの法線と散乱中心軸Ａとのなす角度を散乱中心軸角度θＡ、異方性光拡散フィルムの法線と散乱中心軸Ｂのなす角度を散乱中心軸角度θＢとした場合、θＡおよびθＢは、０°超９０°未満の関係を満たす。
　更に、θＢ＝θＡ±１０°（好ましくはθＢ＝θＡ±５°、より好ましくはθＢ＝θＡ±３°）である。 In the anisotropic light-diffusing film according to the present invention, when the angle of the normal direction of the anisotropic light-diffusing film is 0°, it is more than 0° and less than 90° (preferably 10° to 60°, more preferably 20° to 45° ) have two scattering central axes. That is, as shown in FIG. 7(3), the angle between the normal to the anisotropic light-diffusing film and the scattering center axis A is the scattering center axis angle θ A , and the normal to the anisotropic light-diffusing film and the scattering center axis B When the angle is the scattering central axis angle θ B , θ A and θ B satisfy the relationship of more than 0° and less than 90°.
Furthermore, θ B =θ A ±10° (preferably θ B =θ A ±5°, more preferably θ B =θ A ±3°).
　本発明によれば、一層の異方性光拡散フィルム内部に、上記関係を満たす２つの散乱中心軸（散乱中心軸Ａおよび散乱中心軸Ｂ）が存在することにより、厚みを抑えながら、優れた光学特性を有する異方性光拡散フィルムとなり、上下又は左右等の、対称性を有する２方位への視野角拡大を可能とすることができる。 According to the present invention, two scattering central axes (scattering central axis A and scattering central axis B) that satisfy the above relationship are present inside a single layer of an anisotropic light diffusion film, thereby suppressing the thickness and providing excellent optical properties. It becomes an anisotropic light diffusing film having a , and it is possible to expand the viewing angle in two directions having symmetry, such as up and down or left and right.
＜＜２－１－２　柱状領域＞＞
　前述したように、本発明に係る異方性光拡散フィルムは、散乱中心軸Ａを構成する第１の柱状領域、および、散乱中心軸Ｂを構成する第２の柱状領域、という、延在方向が異なる２つの柱状領域が存在する。 <<2-1-2 Columnar region>>
As described above, the anisotropic light-diffusing film according to the present invention has a first columnar region that forms the central scattering axis A and a second columnar region that forms the central scattering axis B, which extend in different directions. There are two columnar regions.
　以下では、第１の柱状領域に含まれる複数の柱状構造体および第２の柱状領域に含まれる複数の柱状構造体について、共通する構造（短径、長径、アスペクト比）を述べる。第１の柱状領域に含まれる複数の柱状構造体の構造と、第２の柱状領域に含まれる複数の柱状構造体の構造とは、同一であっても異なっていてもよい。
　本発明の第１の柱状領域および第２の柱状領域は、２つの異なる角度から光を照射して樹脂を硬化させて得られるため、各々の光の照射条件を変更することで、第１の柱状領域に含まれる複数の柱状構造体の構造と、第２の柱状領域に含まれる複数の柱状構造体の構造とを、個別に調整することができる。 Hereinafter, common structures (minor axis, major axis, aspect ratio) of the plurality of columnar structures included in the first columnar region and the plurality of columnar structures included in the second columnar region will be described. The structure of the plurality of columnar structures included in the first columnar region and the structure of the plurality of columnar structures included in the second columnar region may be the same or different.
The first columnar region and the second columnar region of the present invention are obtained by irradiating light from two different angles to cure the resin. The structure of the plurality of columnar structures included in the columnar region and the structure of the plurality of columnar structures included in the second columnar region can be individually adjusted.
＜２－１－２－１　短径＞
　柱状構造体の短径の平均値（平均短径）は、０．５μｍ以上であることが好ましく、１．０μｍ以上であることがより好ましく、１．５μｍ以上であることがさらに好ましい。一方、柱状構造体の平均短径は、５．０μｍ以下であることが好ましく、４．０μｍ以下であることがより好ましく、３．０μｍ以下であることがさらに好ましい。これら柱状構造体の短径の下限値および上限値は、適宜組み合わせることができる。 <2-1-2-1 Minor diameter>
The average short diameter (average short diameter) of the columnar structures is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more. On the other hand, the average minor axis of the columnar structures is preferably 5.0 μm or less, more preferably 4.0 μm or less, and even more preferably 3.0 μm or less. The lower limit and upper limit of the minor axis of these columnar structures can be combined as appropriate.
＜２－１－２－２　長径＞
　柱状構造体の長径の平均値（平均長径）は、０．５μｍ以上であることが好ましく、１．０μｍ以上であることがより好ましく、１．５μｍ以上であることがさらに好ましい。一方、柱状構造体の平均長径は、１００μｍ以下であることが好ましく、５０μｍ以下であることがより好ましく、３０μｍ以下であることがさらに好ましい。これら柱状構造体の長径の下限値および上限値は、適宜組み合わせることができる。 <2-1-2-2 Length>
The average major axis (average major axis) of the columnar structures is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more. On the other hand, the average length of the columnar structures is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. The lower limit and upper limit of the major axis of these columnar structures can be combined as appropriate.
＜２－１－２－３　アスペクト比＞
　柱状構造体の平均短径に対する平均長径の比（平均長径／平均短径）、即ち、アスペクト比は、１～２０とすることが好ましく、２未満であることがより好ましい。 <2-1-2-3 Aspect Ratio>
The ratio of the average major axis to the average minor axis of the columnar structure (average major axis/average minor axis), that is, the aspect ratio is preferably 1 to 20, more preferably less than 2.
　本発明の効果をより高めるためには、第１の柱状領域に含まれる複数の柱状構造体と、第２の柱状領域に含まれる複数の柱状構造体とにおいて、アスペクト比の比が、好ましくは１：２～２：１、より好ましくは２：３～３：２、さらに好ましくは９：１０～１０：９である。 In order to further enhance the effect of the present invention, the aspect ratio of the plurality of columnar structures included in the first columnar region and the plurality of columnar structures included in the second columnar region is preferably 1:2 to 2:1, more preferably 2:3 to 3:2, still more preferably 9:10 to 10:9.
＜＜２－１－３　厚み＞＞
　異方性光拡散フィルムの厚みは、好ましくは１５μｍ～１００μｍであり、より好ましくは３０μｍ～８０μｍである。このような範囲とすることで、材料費やＵＶ照射に要する費用等の製造コストを低減させつつ、視覚依存性改善効果を十分なものとすることができる。 <<2-1-3 Thickness>>
The thickness of the anisotropic light-diffusing film is preferably 15 μm to 100 μm, more preferably 30 μm to 80 μm. By setting it in such a range, it is possible to reduce manufacturing costs such as material costs and costs required for UV irradiation, and to achieve a sufficient effect of improving visual dependence.
＜＜＜２－２　異方性光拡散フィルムの物性＞＞＞
＜＜２－２－１　直線透過率＞＞
　本発明に係る異方性光拡散フィルムは、２つの散乱中心軸を有する。そのため、本発明に係る異方性光拡散フィルムの光学プロファイルにおいては、散乱中心軸Ａに対応する入射光角度範囲における直線透過率と、散乱中心軸Ｂに対応する入射光角度範囲における直線透過率とが存在する。 <<<2-2 Physical Properties of Anisotropic Light Diffusion Film>>>
<<2-2-1 Linear transmittance>>
The anisotropic light-diffusing film according to the present invention has two scattering central axes. Therefore, in the optical profile of the anisotropic light diffusion film according to the present invention, the linear transmittance in the incident light angle range corresponding to the scattering central axis A and the linear transmittance in the incident light angle range corresponding to the scattering central axis B are exist.
＜＜２－２－２　極小直線透過率＞＞
　本発明に係る異方性光拡散フィルムは、散乱中心軸Ａと、異方性光拡散フィルムの法線との間の角度における極小直線透過率ＴｍｉｎＡと、散乱中心軸Ｂと、異方性光拡散フィルムの法線との間の角度における極小直線透過率ＴｍｉｎＢとの差の絶対値である、｜ＴｍｉｎＡ－ＴｍｉｎＢ｜が、５パーセントポイント以下あり、３パーセントポイント以下であることが好ましく、１パーセントポイント以下であることがより好ましい。このようにすることで、異方性光拡散フィルムの対称性が向上し、上下又は左右等対称性を有する２方向への視野角拡大を可能とすることができる。 <<2-2-2 Minimum linear transmittance>>
The anisotropic light-diffusing film according to the present invention has a minimum linear transmittance Tmin A at the angle between the scattering central axis A and the normal to the anisotropic light-diffusing film, the scattering central axis B, and the normal to the anisotropic light-diffusing film. |Tmin A −Tmin B |, which is the absolute value of the difference from the minimum linear transmittance Tmin B at the angle between is more preferable. By doing so, the symmetry of the anisotropic light-diffusing film is improved, and it is possible to widen the viewing angle in two directions having vertical or horizontal symmetry.
＜＜２－２－３　最大直線透過率＞＞
　本発明に係る異方性光拡散フィルムは、最大直線透過率が、５０％以下であることが好ましく、３０％以下であることがより好ましい。このようにすることで、異方性光拡散フィルムの対称性が向上し、上下又は左右等対称性を有する２方位への視野角拡大を可能とすることができる。 <<2-2-3 Maximum linear transmittance>>
The anisotropic light-diffusing film according to the present invention preferably has a maximum in-line transmittance of 50% or less, more preferably 30% or less. By doing so, the symmetry of the anisotropic light-diffusing film is improved, and it is possible to expand the viewing angle in two directions having vertical or horizontal symmetry.
　直線透過率は、異方性光拡散フィルムの材料の屈折率（複数の樹脂を用いる場合はその屈折率差）や塗膜の膜厚、ＵＶ照度や構造形成時の温度、などの硬化条件によって調整することができる。直線透過率は、例えば、ＵＶ照射を行う際、塗膜の膜厚が厚く、塗膜の温度が高く、複数の樹脂を用いる場合の屈折率差が大きいほど、減少する傾向にある。 The in-line transmittance is adjusted by the refractive index of the material of the anisotropic light diffusion film (difference in refractive index when multiple resins are used), film thickness of the coating film, UV illuminance, temperature during structure formation, and other curing conditions. be able to. The in-line transmittance tends to decrease, for example, when UV irradiation is performed, the thicker the coating film, the higher the temperature of the coating film, and the greater the refractive index difference in the case of using a plurality of resins.
＜＜２－２－４　ヘイズ値＞＞
　異方性光拡散フィルムのヘイズ値は、４０％以上が好ましく、５０％以上がより好ましい。このような範囲とすることで、本発明の効果をより高めることができる。 <<2-2-4 Haze value>>
The haze value of the anisotropic light-diffusing film is preferably 40% or more, more preferably 50% or more. By setting it as such a range, the effect of this invention can be heightened more.
　ヘイズ値は、異方性光拡散フィルムの材料の屈折率（複数の樹脂を用いる場合はその屈折率差）や塗膜の膜厚、ＵＶ照度や構造形成時の温度などの硬化条件によって調整することができる。ヘイズ値は、例えば、ＵＶ照射を行う際、照射角度が塗膜の法線方向に近く、塗膜の層厚が厚く、塗膜の温度が高く、複数の樹脂を用いる場合の屈折率差が大きいほど、増加する傾向にある。 The haze value can be adjusted by adjusting the refractive index of the material of the anisotropic light diffusion film (difference in refractive index when multiple resins are used), coating film thickness, UV illumination, and curing conditions such as temperature during structure formation. can. For example, when performing UV irradiation, the irradiation angle is close to the normal direction of the coating film, the layer thickness of the coating film is thick, the temperature of the coating film is high, and the refractive index difference when using a plurality of resins is It tends to increase as the size increases.
＜＜＜２－３　異方性光拡散フィルムの製造方法＞＞＞
　以下、異方性光拡散フィルムの製造方法について説明する。 <<<2-3 Method for producing anisotropic light diffusion film>>>
A method for producing an anisotropic light-diffusing film will be described below.
＜＜２－３－１　原料＞＞
　異方性光拡散フィルムの原料について、（１）光重合性化合物、（２）光開始剤、（３）配合量、その他任意成分の順に説明する。 <<2-3-1 Raw materials>>
Raw materials for the anisotropic light-diffusing film will be described in the order of (1) photopolymerizable compound, (2) photoinitiator, (3) blending amount, and other optional components.
＜２－３－１－１　光重合性化合物＞
　光重合性化合物は、ラジカル重合性又はカチオン重合性の官能基を有するマクロモノマー、ポリマー、オリゴマー、モノマーから選択される光重合性化合物と光開始剤とから構成され、紫外線および／又は可視光線を照射することにより重合・硬化する材料である。 <2-3-1-1 Photopolymerizable compound>
The photopolymerizable compound comprises a photopolymerizable compound selected from macromonomers, polymers, oligomers, and monomers having radically polymerizable or cationic polymerizable functional groups, and a photoinitiator, and emits ultraviolet rays and/or visible rays. It is a material that polymerizes and hardens when irradiated.
　ここで、異方性光拡散フィルムを形成する材料が１種類であっても、密度の高低差ができることによって屈折率差が生ずる。ＵＶの照射強度が強い部分は硬化速度が早くなるため、その硬化領域周囲に重合・硬化材料が移動し、結果として屈折率が高くなる領域と屈折率が低くなる領域が形成されるからである。なお、（メタ）アクリレートとは、アクリレート又はメタアクリレートのどちらであってもよいことを意味する。 Here, even if the material forming the anisotropic light-diffusing film is of one type, a difference in refractive index occurs due to the difference in density. This is because the hardening speed increases in areas where the UV irradiation intensity is high, and the polymerized/cured material moves around the hardened area, resulting in the formation of areas with a high refractive index and areas with a low refractive index. . (Meth)acrylate means that it may be either acrylate or methacrylate.
　ラジカル重合性化合物は、主に分子中に１個以上の不飽和二重結合を含有するもので、具体的には、エポキシアクリレート、ウレタンアクリレート、ポリエステルアクリレート、ポリエーテルアクリレート、ポリブタジエンアクリレート、シリコーンアクリレート等の名称で呼ばれるアクリルオリゴマーと、２－エチルヘキシルアクリレート、イソアミルアクリレート、ブトキシエチルアクリレート、エトキシジエチレングリコールアクリレート、フェノキシエチルアクリレート、テトラヒドロフルフリルアクリレート、イソノルボルニルアクリレート、２－ヒドロキシエチルアクリレート、２－ヒドロキシプロピルアクリレート、２－アクリロイロキシフタル酸、ジシクロペンテニルアクリレート、トリエチレングリコールジアクリレート、ネオペンチルグリコールジアクリレート、１，６－ヘキサンジオールジアクリレート、ビスフェノールＡのＥＯ付加物ジアクリレート、トリメチロールプロパントリアクリレート、ＥＯ変性トリメチロールプロパントリアクリレート、ペンタエリスリトールトリアクリレート、ペンタエリスリトールテトラアクリレート、ジトリメチロールプロパンテトラアクリレート、ジペンタエリスリトールヘキサアクリレート等のアクリレートモノマーが挙げられる。又、これらの化合物は、各単体で用いてもよく、複数混合して用いてもよい。なお、同様にメタクリレートも使用可能であるが、一般にはメタクリレートよりもアクリレートの方が、光重合速度が速いので好ましい。 Radically polymerizable compounds mainly contain one or more unsaturated double bonds in the molecule, and specific examples include epoxy acrylates, urethane acrylates, polyester acrylates, polyether acrylates, polybutadiene acrylates, silicone acrylates, and the like. and 2-ethylhexyl acrylate, isoamyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isonorbornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate. , 2-acryloyloxyphthalic acid, dicyclopentenyl acrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, EO adduct diacrylate of bisphenol A, trimethylolpropane triacrylate, Acrylate monomers such as EO-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexaacrylate. Also, these compounds may be used alone or in combination. Methacrylates can also be used, but acrylates are generally preferable to methacrylates because they have a faster photopolymerization rate.
　カチオン重合性化合物としては、分子中にエポキシ基やビニルエーテル基、オキセタン基を１個以上有する化合物が使用できる。エポキシ基を有する化合物としては、２－エチルヘキシルジグリコールグリシジルエーテル、ビフェニルのグリシジルエーテル、ビスフェノールＡ、水添ビスフェノールＡ、ビスフェノールＦ、ビスフェノールＡＤ、ビスフェノールＳ、テトラメチルビスフェノールＡ、テトラメチルビスフェノールＦ、テトラクロロビスフェノールＡ、テトラブロモビスフェノールＡ等のビスフェノール類のジグリシジルエーテル類、フェノールノボラック、クレゾールノボラック、ブロム化フェノールノボラック、オルトクレゾールノボラック等のノボラック樹脂のポリグリシジルエーテル類、エチレングリコール、ポリエチレングリコール、ポリプロピレングリコール、ブタンジオール、１，６－ヘキサンジオール、ネオペンチルグリコール、トリメチロールプロパン、１，４－シクロヘキサンジメタノール、ビスフェノールＡのＥＯ付加物、ビスフェノールＡのＰＯ付加物等のアルキレングリコール類のジグリシジルエーテル類、ヘキサヒドロフタル酸のグリシジルエステルやダイマー酸のジグリシジルエステル等のグリシジルエステル類が挙げられる。 A compound having one or more epoxy groups, vinyl ether groups, or oxetane groups in the molecule can be used as the cationic polymerizable compound. Compounds having an epoxy group include 2-ethylhexyl diglycol glycidyl ether, biphenyl glycidyl ether, bisphenol A, hydrogenated bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetrachloro Diglycidyl ethers of bisphenols such as bisphenol A and tetrabromobisphenol A, polyglycidyl ethers of novolak resins such as phenol novolak, cresol novolak, brominated phenol novolak and ortho-cresol novolak, ethylene glycol, polyethylene glycol, polypropylene glycol, diglycidyl ethers of alkylene glycols such as butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, 1,4-cyclohexanedimethanol, EO adducts of bisphenol A, and PO adducts of bisphenol A; Examples thereof include glycidyl esters such as glycidyl ester of hexahydrophthalic acid and diglycidyl ester of dimer acid.
　エポキシ基を有する化合物としてはさらに、３，４－エポキシシクロヘキシルメチル－３’，４’－エポキシシクロヘキサンカルボキシレート、２－（３，４－エポキシシクロヘキシル－５，５－スピロ－３，４－エポキシ）シクロヘキサン－メタ－ジオキサン、ジ（３，４－エポキシシクロヘキシルメチル）アジペート、ジ（３，４－エポキシ－６－メチルシクロヘキシルメチル）アジペート、３，４－エポキシ－６－メチルシクロヘキシル－３’，４’－エポキシ－６’－メチルシクロヘキサンカルボキシレート、メチレンビス（３，４－エポキシシクロヘキサン）、ジシクロペンタジエンジエポキシド、エチレングリコールのジ（３，４－エポキシシクロヘキシルメチル）エーテル、エチレンビス（３，４－エポキシシクロヘキサンカルボキシレート）、ラクトン変性３，４－エポキシシクロヘキシルメチル－３’，４’－エポキシシクロヘキサンカルボキシレート、テトラ（３，４－エポキシシクロヘキシルメチル）ブタンテトラカルボキシレート、ジ（３，４－エポキシシクロヘキシルメチル）－４，５－エポキシテトラヒドロフタレート等の脂環式エポキシ化合物も挙げられるが、これらに限定されるものではない。 Further examples of compounds having an epoxy group include 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate and 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy). Cyclohexane-meta-dioxane, di(3,4-epoxycyclohexylmethyl)adipate, di(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3',4' -epoxy-6'-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di(3,4-epoxycyclohexylmethyl)ether of ethylene glycol, ethylenebis(3,4-epoxy) cyclohexanecarboxylate), lactone-modified 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate, tetra(3,4-epoxycyclohexylmethyl)butane tetracarboxylate, di(3,4-epoxycyclohexylmethyl) )-4,5-epoxytetrahydrophthalate and other cycloaliphatic epoxy compounds, but are not limited to these.
　ビニルエーテル基を有する化合物としては、例えば、ジエチレングリコールジビニルエーテル、トリエチレングリコールジビニルエーテル、ブタンジオールジビニルエーテル、ヘキサンジオールジビニルエーテル、シクロヘキサンジメタノールジビニルエーテル、ヒドロキシブチルビニルエーテル、エチルビニルエーテル、ドデシルビニルエーテル、トリメチロールプロパントリビニルエーテル、プロペニルエーテルプロピレンカーボネート等が挙げられるが、これらに限定されるものではない。なお、ビニルエーテル化合物は、一般にはカチオン重合性であるが、アクリレートと組み合わせることによりラジカル重合も可能である。 Examples of compounds having a vinyl ether group include diethylene glycol divinyl ether, triethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, hydroxybutyl vinyl ether, ethyl vinyl ether, dodecyl vinyl ether, trimethylolpropane tri vinyl ether, propenyl ether propylene carbonate, etc., but not limited thereto. Vinyl ether compounds are generally cationic polymerizable, but can be radically polymerized by combining them with acrylates.
　又、オキセタン基を有する化合物としては、１，４－ビス［（３－エチル－３－オキセタニルメトキシ）メチル］ベンゼン、３－エチル－３－（ヒドロキシメチル）－オキセタン等が使用できる。 Also, as compounds having an oxetane group, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 3-ethyl-3-(hydroxymethyl)-oxetane and the like can be used.
　なお、以上のカチオン重合性化合物は、各単体で用いてもよく、複数混合して用いてもよい。上記光重合性化合物は、前述のものに限定されるものではない。 The above cationic polymerizable compounds may be used alone or in combination. The photopolymerizable compound is not limited to those mentioned above.
　また、十分な屈折率差を生じさせるべく、上記光重合性化合物には、低屈折率化を図るために、フッ素原子（Ｆ）を導入しても良く、高屈折率化を図るために、硫黄原子（Ｓ）、臭素原子（Ｂｒ）、各種金属原子を導入しても良い。さらに、特表２００５－５１４４８７号公報に開示されるように、酸化チタン（ＴｉＯ２）、酸化ジルコニウム（ＺｒＯ２）、酸化錫（ＳｎＯｘ）等の高屈折率の金属酸化物からなる超微粒子の表面に、アクリル基やメタクリル基、エポキシ基等の光重合性官能基を導入した機能性超微粒子を前述の光重合性化合物に添加することも有効である。 Further, in order to produce a sufficient refractive index difference, fluorine atoms (F) may be introduced into the photopolymerizable compound in order to lower the refractive index. A sulfur atom (S), a bromine atom (Br), and various metal atoms may be introduced. Furthermore, as disclosed in Japanese Patent Application Publication No. 2005-514487, ultrafine particles made of metal oxides with a high refractive index such as titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), tin oxide (SnO x ), etc. It is also effective to add functional ultrafine particles having a photopolymerizable functional group such as an acrylic group, a methacrylic group, or an epoxy group introduced to the surface of the above-described photopolymerizable compound.
　光重合性化合物として、シリコーン骨格を有する光重合性化合物を使用することが好ましい。シリコーン骨格を有する光重合性化合物は、その構造（主にエーテル結合）に伴い配向して重合・硬化し、低屈折率領域、高屈折率領域、又は、低屈折率領域および高屈折率領域を形成する。シリコーン骨格を有する光重合性化合物を使用することによって、柱状構造体を傾斜させやすくなり、正面方向への集光性が向上する。なお、低屈折率領域は柱状領域又はマトリックス領域のいずれか一方に相当するものであり、他方が高屈折率領域に相当する。 A photopolymerizable compound having a silicone skeleton is preferably used as the photopolymerizable compound. A photopolymerizable compound having a silicone skeleton is oriented and polymerized and cured along with its structure (mainly ether bonds) to form a low refractive index region, a high refractive index region, or a low refractive index region and a high refractive index region. Form. By using a photopolymerizable compound having a silicone skeleton, it becomes easier to incline the columnar structure, and light collection in the front direction is improved. The low refractive index region corresponds to either the columnar region or the matrix region, and the other corresponds to the high refractive index region.
　低屈折率領域において、シリコーン骨格を有する光重合性化合物の硬化物であるシリコーン樹脂が相対的に多くなることが好ましい。これによって、散乱中心軸をさらに傾斜させやすくすることができるため、正面方向への集光性が向上する。シリコーン樹脂は、シリコーン骨格を有さない化合物に比べ、ケイ素（Ｓｉ）を多く含有するため、このケイ素を指標として、ＥＤＳ（エネルギー分散型Ｘ線分光器）を使用することによってシリコーン樹脂の相対的な量を確認することができる。 In the low refractive index region, it is preferable that the amount of silicone resin, which is a cured product of a photopolymerizable compound having a silicone skeleton, is relatively large. As a result, the center axis of scattering can be more easily tilted, and the light condensing property in the front direction is improved. Silicone resins contain more silicon (Si) than compounds that do not have a silicone skeleton. amount can be checked.
　シリコーン骨格を有する光重合性化合物は、ラジカル重合性又はカチオン重合性の官能基を有するモノマー、オリゴマー、プレポリマー又はマクロモノマーである。ラジカル重合性の官能基としては、アクリロイル基、メタクリロイル基、アリル基等が挙げられ、カチオン重合性の官能基としては、エポキシ基、オキセタン基等が挙げられる。これらの官能基の種類と数に特に制限はないが、官能基が多いほど架橋密度が上がり、屈折率の差が生じやすいため好ましいことから、多官能のアクリロイル基又はメタクリロイル基を有することが好ましい。又、シリコーン骨格を有する化合物はその構造から他の化合物との相溶性において不十分なことがあるが、そのような場合にはウレタン化して相溶性を高めることができる。本形態では、末端にアクリロイル基又はメタクリロイル基を有するシリコーン・ウレタン・（メタ）アクリレートが好適に用いられる。 A photopolymerizable compound having a silicone skeleton is a monomer, oligomer, prepolymer or macromonomer having a radically polymerizable or cationic polymerizable functional group. Examples of radically polymerizable functional groups include acryloyl groups, methacryloyl groups, and allyl groups, and examples of cationic polymerizable functional groups include epoxy groups and oxetane groups. There are no particular restrictions on the type and number of these functional groups, but the greater the number of functional groups, the higher the crosslink density and the greater the likelihood of a difference in refractive index. . Compounds having a silicone skeleton may have insufficient compatibility with other compounds due to their structure. In such cases, the compatibility can be enhanced by urethanization. In this embodiment, a silicone/urethane/(meth)acrylate having an acryloyl group or a methacryloyl group at its end is preferably used.
　シリコーン骨格を有する光重合性化合物の重量平均分子量（Ｍｗ）は、５００～５０，０００の範囲にあることが好ましい。より好ましくは２，０００～２０，０００の範囲である。重量平均分子量が上記範囲にあることにより、十分な光硬化反応が起こり、異方性光拡散フィルムの各異方性光拡散フィルム内に存在するシリコーン樹脂が配向しやすくなる。シリコーン樹脂の配向に伴い、散乱中心軸を傾斜させやすくなる。 The weight average molecular weight (Mw) of the photopolymerizable compound having a silicone skeleton is preferably in the range of 500 to 50,000. It is more preferably in the range of 2,000 to 20,000. When the weight-average molecular weight is within the above range, a sufficient photocuring reaction occurs, and the silicone resin present in each anisotropic light-diffusing film of the anisotropic light-diffusing film is easily oriented. With the orientation of the silicone resin, it becomes easier to tilt the scattering central axis.
　シリコーン骨格としては、例えば、下記の一般式（１）で示されるものが該当する。一般式（１）において、Ｒ１、Ｒ２、Ｒ３、Ｒ４、Ｒ５、Ｒ６はそれぞれ独立に、メチル基、アルキル基、フルオロアルキル基、フェニル基、エポキシ基、アミノ基、カルボキシル基、ポリエーテル基、アクリロイル基、メタクリロイル基等の官能基を有する。又、一般式（１）中、ｎは１～５００の整数であることが好ましい。 Examples of the silicone skeleton include those represented by the following general formula (1). In general formula (1), R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently a methyl group, an alkyl group, a fluoroalkyl group, a phenyl group, an epoxy group, an amino group and a carboxyl group. , a polyether group, an acryloyl group, a methacryloyl group, and the like. Further, in general formula (1), n is preferably an integer of 1-500.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
　シリコーン骨格を有する光重合性化合物にシリコーン骨格を有さない化合物を配合して、異方性光拡散フィルムを形成すると、低屈折率領域と高屈折率領域が分離して形成されやすくなり、異方性の程度が強くなり好ましい。 When a photopolymerizable compound having a silicone skeleton is blended with a compound having no silicone skeleton to form an anisotropic light-diffusing film, the low refractive index region and the high refractive index region are easily formed separately, resulting in an anisotropic The degree of is strong and is preferable.
　シリコーン骨格を有さない化合物は、光重合性化合物のほかに熱可塑性樹脂、熱硬化性樹脂を用いることができ、これらを併用することもできる。 In addition to photopolymerizable compounds, thermoplastic resins and thermosetting resins can be used as compounds that do not have a silicone skeleton, and these can also be used in combination.
　光重合性化合物としては、ラジカル重合性又はカチオン重合性の官能基を有するポリマー、オリゴマー、モノマーを使用することができる（ただし、シリコーン骨格を有していないものである）。 As the photopolymerizable compound, a polymer, oligomer, or monomer having a radically polymerizable or cationic polymerizable functional group can be used (however, it does not have a silicone skeleton).
　熱可塑性樹脂としては、ポリエステル、ポリエーテル、ポリウレタン、ポリアミド、ポリスチレン、ポリカーボネート、ポリアセタール、ポリ酢酸ビニル、アクリル樹脂とその共重合体や変性物が挙げられる。熱可塑性樹脂を用いる場合においては熱可塑性樹脂が溶解する溶剤を使用して溶解し、塗布、乾燥後に紫外線でシリコーン骨格を有する光重合性化合物を硬化させて異方性光拡散フィルムを成形する。 Thermoplastic resins include polyesters, polyethers, polyurethanes, polyamides, polystyrenes, polycarbonates, polyacetals, polyvinyl acetates, acrylic resins and their copolymers and modified products. When a thermoplastic resin is used, the anisotropic light diffusion film is formed by dissolving the resin in a solvent that dissolves the thermoplastic resin, applying and drying the resin, and then curing the photopolymerizable compound having a silicone skeleton with ultraviolet rays.
　熱硬化性樹脂としては、エポキシ樹脂、フェノール樹脂、メラミン樹脂、尿素樹脂、不飽和ポリエステルとその共重合体や変性物が挙げられる。熱硬化性樹脂を用いる場合においては、紫外線でシリコーン骨格を有する光重合性化合物を硬化させた後に適宜加熱することで、熱硬化性樹脂を硬化させて異方性光拡散フィルムを成形する。 Thermosetting resins include epoxy resins, phenolic resins, melamine resins, urea resins, unsaturated polyesters and their copolymers and modified products. When a thermosetting resin is used, the photopolymerizable compound having a silicone skeleton is cured with ultraviolet light and then heated appropriately to cure the thermosetting resin and form an anisotropic light diffusion film.
　シリコーン骨格を有さない化合物として最も好ましいのは光重合性化合物であり、低屈折率領域と高屈折率領域が分離しやすいことと、熱可塑性樹脂を用いる場合の溶剤が不要で乾燥過程が不要であること、熱硬化性樹脂のような熱硬化過程が不要であることとなど、生産性に優れている。 A photopolymerizable compound is most preferable as a compound that does not have a silicone skeleton. It is easy to separate the low refractive index region and the high refractive index region, and when using a thermoplastic resin, no solvent is required and no drying process is required. It is excellent in productivity because it does not require a thermosetting process unlike a thermosetting resin.
＜２－３－１－２　光開始剤＞
　ラジカル重合性化合物を重合させることのできる光開始剤としては、ベンゾフェノン、ベンジル、ミヒラーズケトン、２－クロロチオキサントン、２，４－ジエチルチオキサントン、ベンゾインエチルエーテル、ベンゾインイソプロピルエーテル、ベンゾインイソブチルエーテル、２，２－ジエトキシアセトフェノン、ベンジルジメチルケタール、２，２－ジメトキシ－１，２－ジフェニルエタン－１－オン、２－ヒドロキシ－２－メチル－１－フェニルプロパン－１－オン、１－ヒドロキシシクロヘキシルフェニルケトン、２－メチル－１－［４－（メチルチオ）フェニル］－２－モルフォリノプロパノン－１、１－［４－（２－ヒドロキシエトキシ）－フェニル］－２－ヒドロキシ－２－メチル－１－プロパン－１－オン、ビス（シクロペンタジエニル）－ビス［２，６－ジフルオロ－３－（ピル－１－イル）フェニル］チタニウム、２－ベンジル－２－ジメチルアミノ－１－（４－モルフォリノフェニル）－ブタノン－１、２，４，６－トリメチルベンゾイルジフェニルフォスフィンオキサイド等が挙げられる。又、これらの化合物は、各単体で用いてもよく、複数混合して用いてもよい。 <2-3-1-2 Photoinitiator>
Photoinitiators capable of polymerizing radically polymerizable compounds include benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2- diethoxyacetophenone, benzyl dimethyl ketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2 -methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1 -one, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(pyr-1-yl)phenyl]titanium, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) -butanone-1,2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like. Also, these compounds may be used alone or in combination.
　カチオン重合性化合物の光開始剤は、光照射によって酸を発生し、この発生した酸により前述のカチオン重合性化合物を重合させることができる化合物であり、一般的には、オニウム塩、メタロセン錯体が好適に用いられる。 The photoinitiator of the cationically polymerizable compound is a compound that generates an acid upon irradiation with light and can polymerize the above-described cationically polymerizable compound with the generated acid. Generally, onium salts and metallocene complexes are It is preferably used.
　オニウム塩としては、ジアゾニウム塩、スルホニウム塩、ヨードニウム塩、ホスホニウム塩、セレニウム塩等が使用され、これらの対イオンには、ＢＦ４ －、ＰＦ６ －、ＡｓＦ６ －、ＳｂＦ６ －等のアニオンが用いられる。具体例としては、４－クロロベンゼンジアゾニウムヘキサフルオロホスフェート、トリフェニルスルホニウムヘキサフルオロアンチモネート、トリフェニルスルホニウムヘキサフルオロホスフェート、（４－フェニルチオフェニル）ジフェニルスルホニウムヘキサフルオロアンチモネート、（４－フェニルチオフェニル）ジフェニルスルホニウムヘキサフルオロホスフェート、ビス［４－（ジフェニルスルホニオ）フェニル］スルフィド－ビス－ヘキサフルオロアンチモネート、ビス［４－（ジフェニルスルホニオ）フェニル］スルフィド－ビス－ヘキサフルオロホスフェート、（４－メトキシフェニル）ジフェニルスルホニウムヘキサフルオロアンチモネート、（４－メトキシフェニル）フェニルヨードニウムヘキサフルオロアンチモネート、ビス（４－ｔ－ブチルフェニル）ヨードニウムヘキサフルオロホスフェート、ベンジルトリフェニルホスホニウムヘキサフルオロアンチモネート、トリフェニルセレニウムヘキサフルオロホスフェート、（η５－イソプロピルベンゼン）（η５－シクロペンタジエニル）鉄（ＩＩ）ヘキサフルオロホスフェート等が挙げられるが、これらに限定されるものではない。又、これらの化合物は、各単体で用いてもよく、複数混合して用いてもよい。 As the onium salts, diazonium salts , sulfonium salts , iodonium salts , phosphonium salts, selenium salts and the like are used. Used. Specific examples include 4-chlorobenzenediazonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl)diphenylsulfonium hexafluoroantimonate, (4-phenylthiophenyl)diphenyl Sulfonium hexafluorophosphate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluoroantimonate, bis[4-(diphenylsulfonio)phenyl]sulfide-bis-hexafluorophosphate, (4-methoxyphenyl) diphenylsulfonium hexafluoroantimonate, (4-methoxyphenyl)phenyliodonium hexafluoroantimonate, bis(4-t-butylphenyl)iodonium hexafluorophosphate, benzyltriphenylphosphonium hexafluoroantimonate, triphenylselenium hexafluorophosphate, (η5-isopropylbenzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate and the like, but are not limited thereto. Also, these compounds may be used alone or in combination.
　光開始剤は、光重合性化合物１００質量部に対して、０．０１～１０質量部が好ましく、より好ましくは０．１～７質量部、さらに好ましくは０．１～５質量部程度配合される。これは、０．０１質量部未満では光硬化性が低下し、１０質量部を超えて配合した場合には、表面だけが硬化して内部の硬化性が低下してしまう弊害、着色、柱状構造の形成の阻害を招くからである。 The photoinitiator is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, and still more preferably about 0.1 to 5 parts by mass with respect to 100 parts by mass of the photopolymerizable compound. be. This is because if the amount is less than 0.01 part by mass, the photocurability is reduced, and if the amount is more than 10 parts by mass, only the surface is cured and the internal curability is reduced. This is because it leads to inhibition of the formation of
＜２－３－１－３　その他の成分＞
　光開始剤は、通常粉体を光重合性化合物中に直接溶解して使用されるが、溶解性が悪い場合は光開始剤を予め極少量の溶剤に高濃度に溶解させたものを使用することもできる。このような溶剤としては光重合性であることがさらに好ましく、具体的には炭酸プロピレン、γ－ブチロラクトン等が挙げられる。また、光重合性を向上させるために公知の各種染料や増感剤を添加することも可能である。さらに、重合速度を調整するため、重合禁止剤などを添加することも可能である。 <2-3-1-3 Other components>
The photoinitiator is usually used by directly dissolving the powder in the photopolymerizable compound, but if the solubility is poor, the photoinitiator should be pre-dissolved in a very small amount of solvent at a high concentration. can also Such a solvent is more preferably photopolymerizable, and specific examples thereof include propylene carbonate and γ-butyrolactone. Also, various known dyes and sensitizers can be added to improve the photopolymerizability. Furthermore, it is possible to add a polymerization inhibitor or the like in order to adjust the polymerization rate.
　さらに、光重合性化合物を加熱により硬化させることのできる熱硬化開始剤を光開始剤と共に併用することもできる。この場合、光硬化の後に加熱することにより光重合性化合物の重合硬化をさらに促進し完全なものにすることが期待できる。光重合性化合物を単独で、又は複数を混合した組成物を硬化させて、異方性光拡散フィルムを形成することができる。 Furthermore, a thermosetting initiator capable of curing the photopolymerizable compound by heating can be used together with the photoinitiator. In this case, it can be expected that the polymerization and curing of the photopolymerizable compound can be further accelerated and completed by heating after photocuring. An anisotropic light-diffusing film can be formed by curing a composition containing a single photopolymerizable compound or a mixture of multiple photopolymerizable compounds.
　光重合性化合物と光硬化性を有しない高分子樹脂の混合物を硬化させることによっても異方性光拡散フィルム形成することができる。 An anisotropic light diffusion film can also be formed by curing a mixture of a photopolymerizable compound and a non-photocurable polymer resin.
　ここで使用できる高分子樹脂としては、アクリル樹脂、スチレン樹脂、スチレン－アクリル共重合体、ポリウレタン樹脂、ポリエステル樹脂、エポキシ樹脂、セルロース系樹脂、酢酸ビニル系樹脂、塩化ビニル－酢酸ビニル共重合体、ポリビニルブチラール樹脂等が挙げられる。これらの高分子樹脂と光重合性化合物は、光硬化前は十分な相溶性を有していることが必要であるが、この相溶性を確保するために各種有機溶剤や可塑剤等を使用することも可能である。 Polymer resins that can be used here include acrylic resins, styrene resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, Polyvinyl butyral resin etc. are mentioned. These polymer resins and photopolymerizable compounds must have sufficient compatibility before photocuring, and various organic solvents and plasticizers are used to ensure this compatibility. is also possible.
　光重合性化合物としてアクリレートを使用する場合は、高分子樹脂としてはアクリル樹脂から選択することが相溶性の点で好ましい。 When acrylate is used as the photopolymerizable compound, it is preferable to select from acrylic resins as the polymer resin in terms of compatibility.
　シリコーン骨格を有する光重合性化合物と、シリコーン骨格を有さない化合物の比率は質量比で１５：８５～８５：１５の範囲にあることが好ましい。より好ましくは３０：７０～７０：３０の範囲である。当該範囲にすることによって、低屈折率領域と高屈折率領域の相分離が進みやすくなるとともに、柱状構造体が傾斜しやすくなる。シリコーン骨格を有する光重合性化合物の比率が下限値未満又は上限値超であると、相分離が進みにくくなってしまい、柱状構造体が傾斜しにくくなる。 The mass ratio of the photopolymerizable compound having a silicone skeleton to the compound having no silicone skeleton is preferably in the range of 15:85 to 85:15. More preferably, it is in the range of 30:70 to 70:30. Within this range, phase separation between the low-refractive-index region and the high-refractive-index region is facilitated, and the columnar structures are easily tilted. If the ratio of the photopolymerizable compound having a silicone skeleton is less than the lower limit or more than the upper limit, phase separation will be difficult to progress, and the columnar structure will be difficult to tilt.
　シリコーン骨格を有する光重合性化合物としてシリコーン・ウレタン・（メタ）アクリレートを使用すると、シリコーン骨格を有さない化合物との相溶性が向上する。これによって、材料の混合比率を幅広くしても柱状構造体を傾斜させることができる。 Using silicone/urethane/(meth)acrylate as a photopolymerizable compound having a silicone skeleton improves compatibility with compounds that do not have a silicone skeleton. As a result, the columnar structure can be tilted even if the mixing ratio of the materials is widened.
　光重合性化合物を含む組成物を調製する際の溶剤としては、例えば、酢酸エチル、酢酸ブチル、アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン、トルエン、キシレン等を使用することができる。 As a solvent for preparing a composition containing a photopolymerizable compound, for example, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, etc. can be used.
＜＜２－３－２　製造プロセス＞＞
　次に、異方性光拡散フィルムの製造プロセスについて説明する。 <<2-3-2 Manufacturing process>>
Next, the manufacturing process of the anisotropic light diffusion film will be described.
　まず、上述の光重合性化合物を含む塗料を、透明ＰＥＴフィルムのような適当な基体上に塗布してシート状に設け、必要に応じて乾燥させて成膜し、未硬化樹脂組成物層を設ける。この未硬化樹脂組成物層上に、光を照射することで、異方性光拡散フィルムを作製することができる。 First, the paint containing the photopolymerizable compound described above is coated on a suitable substrate such as a transparent PET film to form a sheet, and if necessary dried to form a film, forming an uncured resin composition layer. prepare. By irradiating light onto this uncured resin composition layer, an anisotropic light diffusion film can be produced.
　より具体的には、異方性光拡散フィルムの形成工程は、主に、以下の工程を有するものである。
（１）工程１－１：未硬化樹脂組成物層を基体上に設ける工程
（２）工程１－２：光源から平行光線を得る工程
（３）任意工程１－３：指向性をもった光線を得る工程
（４）工程１－４：未硬化樹脂組成物層を硬化させる工程 More specifically, the process of forming the anisotropic light-diffusing film mainly includes the following steps.
(1) Step 1-1: Step of providing an uncured resin composition layer on a substrate (2) Step 1-2: Step of obtaining parallel light from a light source (3) Optional step 1-3: Directive light Step (4) Step 1-4: Step of curing the uncured resin composition layer
　前述したように、本発明に係る異方性光拡散フィルムは、２つの散乱中心軸（散乱中心軸Ａおよび散乱中心軸Ｂ）を有する。未硬化樹脂組成物層に照射する光線を２方向からの照射とすることで、各光線の照射方向に対応する形で、散乱中心軸Ａおよび散乱中心軸Ｂが延在される。光線の照射角度以外の条件を変更することで、第１の柱状領域に含まれる柱状構造体の構造と、第２の柱状領域に含まれる柱状構造体の構造とを異質な構造とすることができる。
　また、光線の進路上にプリズムシートを配置し、光線を２方向へと分割して照射することで、２方向からの照射とすることも可能である。このようにプリズムレンズを使用した製造方法の場合、光線の照射角度が異なる以外は同質の光線が２方向から照射されることとなり、第１の柱状領域の複数の柱状構造体と、第２の柱状領域の複数の柱状構造体とを、傾斜方向以外は略同一の構造体とすることができる。 As described above, the anisotropic light-diffusing film according to the present invention has two scattering central axes (scattering central axis A and scattering central axis B). By irradiating the uncured resin composition layer with light from two directions, the scattering center axis A and the scattering center axis B are extended in a form corresponding to the irradiation direction of each light. By changing the conditions other than the irradiation angle of the light beam, the structure of the columnar structures included in the first columnar region and the structure of the columnar structures included in the second columnar region can be made different. can.
Further, by arranging a prism sheet on the path of the light beam and dividing the light beam into two directions for irradiation, it is possible to irradiate the light beam from two directions. In the case of the manufacturing method using the prism lens as described above, light beams of the same quality are irradiated from two directions except that the irradiation angles of the light beams are different. A plurality of columnar structures in the columnar region can be substantially the same structure except for the tilt direction.
＜２－３－２－１　工程１－１：未硬化樹脂組成物層を基体上に設ける工程＞
　光重合性化合物を含む塗料を、基体上に、シート状に、未硬化樹脂組成物層として設ける手法は、通常の塗工方式や印刷方式が適用される。具体的には、エアドクターコーティング、バーコーティング、ブレードコーティング、ナイフコーティング、リバースコーティング、トランスファロールコーティング、グラビアロールコーティング、キスコーティング、キャストコーティング、スプレーコーティング、スロットオリフィスコーティング、カレンダーコーティング、ダムコーティング、ディップコーティング、ダイコーティング等のコーティングや、グラビア印刷等の凹版印刷、スクリーン印刷等の孔版印刷等の印刷等が使用できる。塗料が低粘度の場合は、基体の周囲に一定の高さの堰を設けて、この堰で囲まれた中に塗料をキャストすることもできる。 <2-3-2-1 Step 1-1: Step of Providing Uncured Resin Composition Layer on Substrate>
A usual coating method or printing method is applied to the technique of providing the coating material containing the photopolymerizable compound on the substrate in the form of a sheet as an uncured resin composition layer. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calender coating, dam coating, dip coating , coating such as die coating, intaglio printing such as gravure printing, and printing such as stencil printing such as screen printing can be used. If the paint has a low viscosity, a weir of a certain height can be provided around the substrate and the paint can be cast into the area surrounded by this weir.
　工程１－１において、未硬化樹脂組成物層の酸素阻害を防止して、異方性光拡散フィルムの特徴である柱状構造体を効率良く形成させるために、未硬化樹脂組成物層の光照射側に密着して光の照射強度を局所的に変化させるマスクを積層することも可能である。 In step 1-1, in order to prevent oxygen inhibition of the uncured resin composition layer and efficiently form a columnar structure, which is a feature of an anisotropic light diffusion film, on the light irradiation side of the uncured resin composition layer It is also possible to laminate a mask that is in close contact and locally changes the irradiation intensity of light.
　マスクの材質としては、カーボン等の光吸収性のフィラーをマトリックス中に分散したもので、入射光の一部はカーボンに吸収されるが、それ以外の入射光が十分に透過できるような構成のものが好ましい。このようなマトリックスとしては、ＰＥＴ、ＴＡＣ、ＰＶＡｃ、ＰＶＡ、アクリル、ポリエチレン等の透明プラスチックや、ガラス、石英等の無機物や、これらのマトリックスを含むシートに紫外線透過量を制御するためのパターニングや紫外線を吸収する顔料を含んだものであっても構わない。 As for the material of the mask, a light absorbing filler such as carbon is dispersed in the matrix. Part of the incident light is absorbed by the carbon, but the rest of the incident light is sufficiently transmitted. things are preferred. Examples of such a matrix include transparent plastics such as PET, TAC, PVAc, PVA, acryl, and polyethylene; inorganic materials such as glass and quartz; It may contain a pigment that absorbs the
　このようなマスクを用いない場合には、窒素雰囲気下で光照射を行うことで、未硬化樹脂組成物層の酸素阻害を防止することも可能である。また、通常の透明フィルムを未硬化樹脂組成物層上に積層するだけでも、酸素阻害を防ぎ柱状領域の形成を促す上で有効である。このようなマスクや透明フィルムを介した光照射では、光重合性化合物を含む塗料中に、その照射強度に応じた光重合反応を生じるため、屈折率分布を生じ易く、本形態に係る異方性光拡散フィルムの作製に有効である。 When such a mask is not used, it is possible to prevent oxygen inhibition of the uncured resin composition layer by performing light irradiation in a nitrogen atmosphere. Also, simply laminating a normal transparent film on the uncured resin composition layer is effective in preventing oxygen inhibition and promoting the formation of columnar regions. Light irradiation through such a mask or transparent film causes a photopolymerization reaction in the paint containing the photopolymerizable compound according to the irradiation intensity, so that a refractive index distribution is likely to occur. Effective for making diffusion films.
＜２－３－２－２　工程１－２：光源から平行光線を得る工程＞
　光源としては、通常はショートアークの紫外線発生光源が使用され、具体的には高圧水銀灯、低圧水銀灯、メタハライドランプ、キセノンランプ等が使用可能である。このとき、所望の散乱中心軸と平行な光線を得る必要があるが、このような平行光線は、例えば点光源を配置して、この点光源と未硬化樹脂組成物層の間に平行光線を照射するためのフレネルレンズ等の光学レンズを配置する他、光源の背後に反射鏡を配置して、所定の方向に点光源として光が出射するようにすること等で、得ることができる。 <2-3-2-2 Step 1-2: Step of Obtaining Parallel Light from Light Source>
As the light source, a short-arc ultraviolet light source is usually used, and specifically, a high-pressure mercury lamp, a low-pressure mercury lamp, a methhalide lamp, a xenon lamp, or the like can be used. At this time, it is necessary to obtain a light beam parallel to the desired scattering center axis. In addition to arranging an optical lens such as a Fresnel lens for irradiation, it can be obtained by arranging a reflecting mirror behind the light source so that light is emitted as a point light source in a predetermined direction.
＜２－３－２－３　任意工程１－３：指向性をもった光線を得る工程＞
　任意工程１－３は、平行光線を指向性拡散素子に入射させ、指向性をもった光線を得る工程である。図８は、任意工程１－３による本発明の異方性光拡散フィルムの製造方法を示す模式図である。 <2-3-2-3 Optional Step 1-3: Step of Obtaining Directive Light Rays>
Optional step 1-3 is a step of making parallel light beams incident on a directional diffusion element to obtain light beams with directivity. FIG. 8 is a schematic diagram showing a method for manufacturing an anisotropic light-diffusing film of the present invention by optional step 1-3.
　任意工程１－３で用いられる指向性拡散素子３０１および３０２は、光源３００から入射した平行光線Ｄに指向性を付与するものであればよい。 The directional diffusing elements 301 and 302 used in the optional step 1-3 should just impart directivity to the parallel light beams D incident from the light source 300 .
　図８においては指向性をもった光Ｅが、Ｘ方向に多く拡散し、Ｙ方向にはほとんど拡散しない態様にて、未硬化樹脂組成物層３０３に入射することを記載している。このように指向性をもった光を得るためには、例えば、指向性拡散素子３０１および３０２内に、アスペクト比の高い針状フィラーを含有させるとともに、当該針状フィラーをＹ方向に長軸方向が延存するように配向させる方法を採用することができる。指向性拡散素子３０１および３０２は、針状フィラーを使用する方法以外に、種々の方法を使用することができる。 FIG. 8 describes that the directional light E is incident on the uncured resin composition layer 303 in such a manner that it diffuses much in the X direction and scarcely diffuses in the Y direction. In order to obtain light with such directivity, for example, needle-like fillers having a high aspect ratio are contained in the directional diffusion elements 301 and 302, and the needle-like fillers are arranged in the Y direction in the long axis direction. It is possible to adopt a method of orienting such that the Directional diffusion elements 301 and 302 can use various methods other than the method of using needle-like fillers.
　ここで、指向性をもった光Ｅのアスペクト比は、２～２０とすることが好ましい。当該アスペクト比にほぼ対応した、アスペクト比を有する柱状領域が形成される。上記アスペクト比の上限値は、１０以下であることがより好ましく、５以下であることがさらに好ましい。アスペクト比が２０超では、干渉虹やギラツキを生じるおそれがある。 Here, the aspect ratio of the light E with directivity is preferably 2-20. A columnar region having an aspect ratio substantially corresponding to the aspect ratio is formed. The upper limit of the aspect ratio is more preferably 10 or less, even more preferably 5 or less. If the aspect ratio exceeds 20, interference rainbows and glare may occur.
　任意工程１－３においては、指向性をもった光Ｅの広がりを調整することにより、形成される柱状領域の大きさ（アスペクト比、短径ＳＡ、長径ＬＡ等）を適宜定めることができる。例えば、図８（ａ）、（ｂ）のいずれにおいても、本形態の異方性光拡散フィルムを得ることができる。図８（ａ）と（ｂ）で異なるのは、指向性をもった光Ｅの広がりが、（ａ）では大きいのに対し（ｂ）では小さいことである。指向性をもった光Ｅの広がりの大きさに依存して、柱状領域の大きさが異なることとなる。 In the optional step 1-3, by adjusting the spread of the light E with directivity, the sizes of the columnar regions to be formed (aspect ratio, minor axis SA, major axis LA, etc.) can be appropriately determined. For example, the anisotropic light-diffusing film of this embodiment can be obtained in both FIGS. The difference between FIGS. 8A and 8B is that the spread of the light E with directivity is large in FIG. 8A and small in FIG. 8B. The size of the columnar region differs depending on the size of the spread of the light E having directivity.
　指向性をもった光Ｅの広がりは、主に指向性拡散素子３０１および３０２の種類と、未硬化樹脂組成物層３０３との距離に依存する。当該距離を短くするにつれ柱状領域の大きさは小さくなり、長くするにつれ柱状領域の大きさは大きくなる。従って、当該距離を調整することにより、柱状領域の大きさを調整することができる。 The spread of the light E with directivity mainly depends on the types of the directional diffusion elements 301 and 302 and the distance from the uncured resin composition layer 303 . The shorter the distance, the smaller the size of the columnar region, and the longer the distance, the larger the size of the columnar region. Therefore, by adjusting the distance, the size of the columnar region can be adjusted.
＜２－３－２－４　工程１－４：未硬化樹脂組成物層を硬化させる工程＞
　未硬化樹脂組成物層に照射して、未硬化樹脂組成物層を硬化させる光線は、光重合性化合物を硬化可能な波長を含んでいることが必要で、通常は水銀灯の３６５ｎｍを中心とする波長の光が利用される。この波長帯を使って異方性光拡散フィルムを作製する場合、照度としては０．０１ｍＷ／ｃｍ２～１００ｍＷ／ｃｍ２の範囲が好ましく、０．１ｍＷ／ｃｍ２～２０ｍＷ／ｃｍ２　がより好ましい。照度が０．０１ｍＷ／ｃｍ２未満であると、硬化に長時間を要するため、生産効率が悪くなり、１００ｍＷ／ｃｍ２を超えると、光重合性化合物の硬化が速すぎて構造形成を生じず、目的の光学特性を発現できなくなるからである。 <2-3-2-4 Step 1-4: Step of curing the uncured resin composition layer>
The light beam that is applied to the uncured resin composition layer to cure the uncured resin composition layer must contain a wavelength capable of curing the photopolymerizable compound, and is usually centered at 365 nm of a mercury lamp. wavelengths of light are used. When producing an anisotropic light diffusion film using this wavelength band, the illuminance is preferably in the range of 0.01 mW/cm 2 to 100 mW/cm 2 , more preferably 0.1 mW/cm 2 to 20 mW/cm 2 . When the illuminance is less than 0.01 mW/cm 2 , it takes a long time for curing, resulting in poor production efficiency. , the desired optical characteristics cannot be exhibited.
　なお、光の照射時間は特に限定されないが、１０秒間～１８０秒間が好ましく、３０秒間～１２０秒間がより好ましい。 Although the light irradiation time is not particularly limited, it is preferably 10 seconds to 180 seconds, more preferably 30 seconds to 120 seconds.
　前述したように、照射する光線を２方向からの照射とすることで、本発明に係る異方性光拡散フィルムを得ることができる。 As described above, the anisotropic light-diffusing film according to the present invention can be obtained by irradiating light from two directions.
　異方性光拡散フィルムは、前述の如く、低照度の光を比較的長時間照射することにより、未硬化樹脂組成物層中に、特定の内部構造が形成されることで得られるものである。そのため、このような光照射だけでは未反応のモノマー成分が残存して、べたつきを生じたりしてハンドリング性や耐久性に問題がある場合がある。そのような場合は、１０００ｍＷ／ｃｍ２以上の高照度の光を追加照射して残存モノマーを重合させることができる。このときの光照射はマスクを積層した側の逆側から行ってもよい。 As described above, the anisotropic light diffusion film is obtained by forming a specific internal structure in the uncured resin composition layer by irradiating the film with low-intensity light for a relatively long time. Therefore, such light irradiation alone may leave unreacted monomer components, causing stickiness and problems in handleability and durability. In such a case, the residual monomer can be polymerized by additionally irradiating light with a high illuminance of 1000 mW/cm 2 or more. At this time, light irradiation may be performed from the side opposite to the side on which the mask is laminated.
　前述したように、未硬化樹脂組成物層を硬化させる際に、未硬化樹脂組成物層に照射される光の角度を調整することにより、得られる異方性光拡散フィルムの散乱中心軸を所望のものとすることができる。 As described above, when the uncured resin composition layer is cured, the scattering center axis of the resulting anisotropic light-diffusing film can be set to a desired value by adjusting the angle of light with which the uncured resin composition layer is irradiated. can be
＜＜＜＜２－４　異方性光拡散フィルムの用途＞＞＞＞
　異方性光拡散フィルムは、視野角依存性改善効果に優れることから、液晶表示装置、有機ＥＬ表示装置、プラズマディスプレイ等のあらゆる表示装置に適用することができる。 <<<<2-4 Applications of Anisotropic Light Diffusion Film>>>>
Since the anisotropic light diffusion film is excellent in the effect of improving the viewing angle dependence, it can be applied to all display devices such as liquid crystal display devices, organic EL display devices, and plasma displays.
　異方性光拡散フィルムは、視野角依存性の問題が生じ易いＴＮ方式の液晶においても特に好ましく使用することができる。 The anisotropic light-diffusing film can be used particularly preferably in TN liquid crystals, which tend to have viewing angle dependency problems.
　ここで、本発明によれば、液晶層と、異方性光拡散フィルムと、を含む液晶表示装置を提供することが可能である。この場合、異方性光拡散フィルムは、液晶層よりも視認側に設けられている。液晶表示装置は、ＴＮ方式、ＶＡ方式、ＩＰＳ方式などのいずれでもよい。より具体的には、一般的な液晶装置は、表示装置から視認側に向かって、光源、偏光板、ガラス基板、透明電極膜、液晶層、透明電極膜、カラーフィルター、ガラス基板、偏光板の順番で積層された層構造を有し、また、適宜の機能層を更に有するが、異方性光拡散フィルムは、液晶層よりも視認側となるいずれの箇所に設けられていてもよい。 Here, according to the present invention, it is possible to provide a liquid crystal display device including a liquid crystal layer and an anisotropic light diffusion film. In this case, the anisotropic light-diffusing film is provided on the viewing side of the liquid crystal layer. The liquid crystal display device may be of any of the TN system, VA system, IPS system, and the like. More specifically, a general liquid crystal device includes a light source, a polarizing plate, a glass substrate, a transparent electrode film, a liquid crystal layer, a transparent electrode film, a color filter, a glass substrate, and a polarizing plate from the display device toward the viewing side. Although it has a layered structure in which it is laminated in order and further has an appropriate functional layer, the anisotropic light-diffusing film may be provided anywhere on the viewing side of the liquid crystal layer.
　また、本発明によれば、発光層と、異方性光拡散フィルムと、を含む有機ＥＬ表示装置を提供することが可能である。この場合、異方性光拡散フィルムは、発光層（発光層に接続された電極を含む。）よりも視認側に設けられている（積層されている）。有機ＥＬ表示装置は、トップエミッション方式、ボトムエミッション方式などのいずれの方式でもよいし、また、カラーの有機ＥＬ表示装置である場合には、ＲＧＢ塗り分け方式、カラーフィルター方式などのいずれでもよい。また、有機ＥＬ表示装置は、更に多層化されたものであってもよい。 Further, according to the present invention, it is possible to provide an organic EL display device including a light emitting layer and an anisotropic light diffusion film. In this case, the anisotropic light-diffusing film is provided (stacked) on the viewing side of the light-emitting layer (including the electrode connected to the light-emitting layer). The organic EL display device may be of any type such as a top emission method or a bottom emission method, and in the case of a color organic EL display device, may be of any type such as an RGB coloring method or a color filter method. Also, the organic EL display device may be a multilayered one.
＜＜＜実施例＞＞＞
　次に、本発明を実施例および比較例により、更に具体的に説明するが、本発明は、これらの例によって何ら限定されるものではない。 <<<Example>>>
EXAMPLES Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited by these examples.
＜＜異方性光拡散フィルムおよび異方性光拡散フィルム積層体の作製＞＞
　厚み１００μｍのＰＥＴフィルム（東洋紡社製、商品名：Ａ４３００）の縁部全周に、ディスペンサーを使い、硬化性樹脂で高さ３０μｍ又は６０μｍの隔壁を形成した。この中に下記の紫外線硬化する光重合性化合物を含む塗料を滴下し、別のＰＥＴフィルムでカバーした。 <<Production of anisotropic light diffusion film and anisotropic light diffusion film laminate>>
Partition walls with a height of 30 μm or 60 μm were formed with a curable resin using a dispenser around the entire edge of a 100 μm-thick PET film (manufactured by Toyobo Co., Ltd., trade name: A4300). A paint containing the following UV-curable photopolymerizable compound was dripped into this and covered with another PET film.
・シリコーン・ウレタン・アクリレート(屈折率：１．４６０、重量平均分子量：５８９０)　２０重量部
（ＲＡＨＮ社製、商品名：００－２２５／ＴＭ１８）
・ネオペンチルグリコールジアクリレート(屈折率：１．４５０)　３０重量部
(ダイセルサイテック社製、商品名Ｅｂｅｃｒｙｌ１４５)
・ビスフェノールＡのＥО付加物ジアクリレート(屈折率：１．５３６)　１５重量部
(ダイセルサイテック社製、商品名Ｅｂｅｃｒｙｌ１５０)
・フェノキシエチルアクリレート(屈折率１．５１８)　４０重量部
(共栄社化学製、商品名：ライトアクリレートＰО－Ａ)
・２，２－ジメトキシ－１，２－ジフェニルエタン－１－オン　４重量部
(ＢＡＳＦ社製、商品名：Ｉｒｇａｃｕｒｅ６５１) ・Silicone urethane acrylate (refractive index: 1.460, weight average molecular weight: 5890) 20 parts by weight (manufactured by RAHN, trade name: 00-225/TM18)
・Neopentyl glycol diacrylate (refractive index: 1.450) 30 parts by weight
(manufactured by Daicel Cytec, trade name Ebecryl145)
・ EO adduct diacrylate of bisphenol A (refractive index: 1.536) 15 parts by weight
(manufactured by Daicel Cytec, trade name Ebecryl150)
・ Phenoxyethyl acrylate (refractive index 1.518) 40 parts by weight
(Made by Kyoeisha Chemical, trade name: Light Acrylate PO-A)
· 2,2-dimethoxy-1,2-diphenylethan-1-one 4 parts by weight
(manufactured by BASF, trade name: Irgacure651)
＜散乱中心軸を２つ有する異方性光拡散フィルムの作製＞
　両面をＰＥＴフィルムで挟まれた６０μｍの厚みの液膜に対して、ＵＶスポット光源（浜松ホトニクス社製、商品名：Ｌ２８５９－０１）の落射用照射ユニットから、照射強度１０ｍＷ／ｃｍ２～１００ｍＷ／ｃｍ２の平行光線である紫外線を照射した。このとき、光源と液膜の間にプリズムシートを設置し、平行光線を２方向へと分割し、２方向の平行光線の方位角１８０°にて、照射した。
　液膜の厚み、ＵＶ照度、平行光線照射時の液膜温度などのパラメータを変えることで、表１の特性を有する散乱中心軸を２つ有する異方性光拡散フィルム１～５を得た。
　なお、２つの散乱中心軸は、直線透過光量の測定により光学プロファイルを作成したとき（後に測定詳細説明）、光拡散性が略対称性を有する入射光角度で、０°よりもプラス側に位置する角度（直線透過率極小値間に挟まれた略中央部（拡散領域の中央部）の角度）を、散乱中心軸Ａの散乱中心軸角度θＡとして得て、０°よりもマイナス側に位置する角度を、散乱中心軸Ｂの散乱中心軸角度θＢとして得た。
　また、得られた、各異方性光拡散フィルムの方位角は、直線透過光量の測定で、図６に示す配置において、散乱中心軸Ａの方位角φＡを０°とし、且つ、１°ずつ、図６の配置から、各異方性光拡散フィルムを回転させて（図６の回転を示す円状の両矢印が垂直になった回転、ただし、直線Ｖはそのまま）、各回転角度毎の光学プロファイルを作成したとき、各グラフ形状で散乱中心軸角度付近の直線透過率の変曲が確認されたグラフの回転角度を、散乱中心軸Ｂの方位角φＢとすると、方位角φＢは、全て１８０°だった。これは、２方向の平行光線の方位角と一致した。
　なお、以降、区別のため、作製した異方性光拡散フィルムの光線照射側面を「照射表面」、反対側面を「裏面」と称す。 <Preparation of anisotropic light diffusion film having two scattering central axes>
A liquid film having a thickness of 60 μm sandwiched between PET films on both sides was irradiated with an intensity of 10 mW/cm 2 to 100 mW/ from an epi-illumination unit of a UV spot light source (manufactured by Hamamatsu Photonics, trade name: L2859-01). Ultraviolet rays, which are parallel rays of cm 2 , were irradiated. At this time, a prism sheet was placed between the light source and the liquid film to split the parallel rays into two directions, and the parallel rays in the two directions were irradiated at an azimuth angle of 180°.
Anisotropic light diffusion films 1 to 5 having two scattering central axes and having the characteristics shown in Table 1 were obtained by changing parameters such as liquid film thickness, UV illuminance, and liquid film temperature during parallel light irradiation.
The two scattering central axes are located on the positive side of 0° at the incident light angle at which the light diffusion is approximately symmetrical when an optical profile is created by measuring the amount of linearly transmitted light (details of measurement will be described later). The angle (the angle of the central portion (central portion of the diffusion region) sandwiched between the linear transmittance minimum values) is obtained as the scattering central axis angle θ A of the scattering central axis A, and is on the minus side of 0° The angle at which it lies was taken as the scattering central axis angle θ B of the scattering central axis B.
Further, the obtained azimuth angle of each anisotropic light diffusion film was determined by measuring the amount of linearly transmitted light. In the arrangement shown in FIG. From the arrangement of FIG. 6, each anisotropic light diffusion film is rotated (rotated so that the circular double-headed arrow indicating rotation in FIG. 6 is vertical, but the straight line V remains as it is), and the optical profile for each rotation angle is obtained. When the rotation angle of the graph at which the inflection of the linear transmittance near the scattering central axis angle was confirmed in each graph shape when it was created, is the azimuth angle φ B of the scattering central axis B, the azimuth angle φ B is all 180. ° was This coincided with the azimuth angle of parallel rays in two directions.
For distinction, the side of the produced anisotropic light-diffusing film irradiated with light is hereinafter referred to as the "irradiated surface", and the opposite side is referred to as the "rear surface".
＜散乱中心軸を１つ有する異方性光拡散フィルムの作製＞
　両面をＰＥＴフィルムで挟まれた３０μｍの厚みの液膜に対して、ＵＶスポット光源（浜松ホトニクス社製、商品名：Ｌ２８５９－０１）の落射用照射ユニットから、照射強度１０ｍＷ／ｃｍ２～１００ｍＷ／ｃｍ２の平行光線である紫外線を照射した。照射角度や液膜の厚み、ＵＶ照度、平行光線照射時の液膜温度などのパラメータを変えることで、表１の特性を有する散乱中心軸を１つ有する異方性光拡散フィルム６～８を得た。 <Preparation of anisotropic light diffusion film having one scattering central axis>
A liquid film having a thickness of 30 μm sandwiched between PET films on both sides was irradiated with an intensity of 10 mW/cm 2 to 100 mW/ from an epi-illumination unit of a UV spot light source (manufactured by Hamamatsu Photonics, trade name: L2859-01). Ultraviolet rays, which are parallel rays of cm 2 , were irradiated. Anisotropic light diffusion films 6 to 8 having one scattering central axis and having the characteristics shown in Table 1 were obtained by changing parameters such as the irradiation angle, liquid film thickness, UV illuminance, and liquid film temperature during parallel light irradiation. .
＜散乱中心軸を２つ有する異方性光拡散フィルム積層体の作製＞
　異方性光拡散フィルム６を２枚準備し、２枚の散乱中心軸が互い違いとなるよう、傾斜方位を１８０°ずらし、５μｍの厚みの透明粘着を介して積層し、散乱中心軸を２つ有する異方性光拡散フィルム積層体１を得た。このとき、異方性光拡散フィルム６の照射表面に透明粘着を介し２つ目の異方性光拡散フィルム６の裏面を積層した。
　なお、以降、区別のため、作製した異方性光拡散フィルム積層体を構成する異方性光拡散フィルムの露出面である照射表面側を「積層体表面」、異方性光拡散フィルム積層体を構成する異方性光拡散フィルムの露出面である裏面側を「積層体裏面」と称す。
　また、異方性光拡散フィルム積層体を構成する異方性光拡散フィルムの内、積層体表面を有する異方性光拡散フィルムの散乱中心軸が、散乱中心軸Ａで、散乱中心軸角度θＡを有するものとし、積層体裏面を有する異方性光拡散フィルムの散乱中心軸が、散乱中心軸Ｂで、散乱中心軸角度θＢを有するものとした。
　続いて異方性光拡散フィルム７および８も、異方性光拡散フィルム７による異方性光拡散フィルム積層体１作製と同様の製法を行い、それぞれ異方性光拡散フィルム積層体２および３を得た。特性を含め、表１に示した。 <Production of an anisotropic light diffusion film laminate having two scattering central axes>
Two sheets of anisotropic light diffusion film 6 were prepared, and the azimuths of inclination of the two sheets were shifted by 180° so that the central scattering axes of the two sheets were alternated. An anisotropic light diffusion film laminate 1 was obtained. At this time, the back surface of the second anisotropic light-diffusing film 6 was laminated on the irradiated surface of the anisotropic light-diffusing film 6 via a transparent adhesive.
Hereinafter, for distinction, the exposed surface of the anisotropic light-diffusing film constituting the produced anisotropic light-diffusing film laminate is referred to as the "laminate surface", and the anisotropic light diffusion constituting the anisotropic light-diffusing film laminate is hereinafter referred to as the "laminate surface". The back side, which is the exposed surface of the film, is referred to as the "back side of the laminate".
Further, among the anisotropic light-diffusing films constituting the anisotropic light-diffusing film laminate, the scattering central axis of the anisotropic light-diffusing film having the surface of the laminate is the scattering central axis A and has the scattering central axis angle θ A , The scattering central axis of the anisotropic light-diffusing film having the back surface of the laminate was assumed to be the scattering central axis B and to have the scattering central axis angle θB .
Subsequently, the anisotropic light-diffusing films 7 and 8 were produced in the same manner as the anisotropic light-diffusing film laminate 1 using the anisotropic light-diffusing film 7 to obtain anisotropic light-diffusing film laminates 2 and 3, respectively. It is shown in Table 1, including the characteristics.
＜＜特性測定＞＞
　特性測定は、以下方法に従った。 <<Characteristics measurement>>
The properties were measured according to the following methods.
＜厚み＞
　実施例で得られた異方性光拡散フィルムおよび異方性光拡散フィルム積層体に対し、マイクロメーター（ミツトヨ社製）を用いて測定を行った。測定値は、作製した異方性光拡散フィルムおよび異方性光拡散フィルム積層体の平面における４つの角付近と、平面における中央付近の１箇所とを含む計５箇所で測定した値の平均値を、厚みとした。 <Thickness>
The anisotropic light-diffusing films and the anisotropic light-diffusing film laminates obtained in Examples were measured using a micrometer (manufactured by Mitutoyo Corporation). The measured value is the average value of the values measured at a total of 5 points including the vicinity of 4 corners on the plane of the produced anisotropic light diffusion film and the anisotropic light diffusion film laminate and 1 point near the center of the plane. did.
＜直線透過率、散乱中心軸角度＞
　図６に示すような、光源の投光角、検出器の受光角を任意に可変できる変角光度計ゴニオフォトメータ（ジェネシア社製）を用いて、実施例で得られた異方性光拡散フィルムおよび異方性光拡散フィルム積層体の直線透過光量の測定を行った。光源からの直進光を受ける位置に検出器を固定し、その間のサンプルホルダーに実施例で得られた異方性光拡散フィルムおよび異方性光拡散フィルム積層体をセットした。なお、この直線Ｖは、散乱中心軸の傾斜方位に垂直な異方性光拡散フィルム上の線となるように配置した。
　また、光源からの光の入射側が、異方性光拡散フィルムでは照射表面側に、異方性光拡散フィルム積層体では積層体表面側で、且つ、積層体表面を有する異方性光拡散フィルムの散乱中心軸角度θＡが、正の値となるようにして、設置した。
　図６に示すように直線Ｖを回転軸としてサンプルを回転させて、それぞれの入射光角度に対応する直線透過光量を測定し、直線透過率を算出し、直線透過率を角度ごとにプロットし、光学プロファイルを作成した。この評価方法によって、どの角度の範囲で入射される光が拡散するかを評価することができる。直線透過光量の測定は、視感度フィルターを用いて可視光領域の波長において測定した。
　以上のような測定の結果得られた光学プロファイルに基づき、直線透過率の最大値である最大直線透過率および当該最大直線透過率での入射光角度を得た。
　また、散乱中心軸を２つ有する異方性光拡散フィルムのとき、光拡散性が略対称性を有する入射光角度で、０°よりもプラス側に位置する角度（直線透過率極小値間に挟まれた略中央部（拡散領域の中央部）の角度）を、散乱中心軸Ａの散乱中心軸角度θＡとして得て、０°よりもマイナス側に位置する角度（直線透過率極小値間に挟まれた略中央部（拡散領域の中央部）の角度）を、散乱中心軸Ｂの散乱中心軸角度θＢとして得た。
　さらに、散乱中心軸を１つ有する異方性光拡散フィルムのとき、光拡散性が略対称性を有する入射光角度（直線透過率極小値間に挟まれた略中央部（拡散領域の中央部）の角度）を、散乱中心軸Ａの散乱中心軸角度θＡとして得た。
　そして、散乱中心軸を２つ有する異方性光拡散フィルムのとき、散乱中心軸Ａと、異方性光拡散フィルム平面法線との間の角度における極小直線透過率をＴｍｉｎＡと、散乱中心軸Ｂと、異方性光拡散フィルム平面法線との間の角度における極小直線透過率をＴｍｉｎＢとを得て、｜ＴｍｉｎＡ－ＴｍｉｎＢ｜を算出した。
　さらに、散乱中心軸を１つ有する異方性光拡散フィルムのとき、散乱中心軸と、異方性光拡散フィルム平面法線との間の角度における極小直線透過率をＴｍｉｎＡとして得た。 <Linear Transmittance, Scattering Central Axis Angle>
As shown in FIG. 6, the anisotropic light diffusion film obtained in the example and the The linear transmitted light amount of the anisotropic light diffusion film laminate was measured. A detector was fixed at a position where it received rectilinear light from the light source, and the anisotropic light-diffusing film and the anisotropic light-diffusing film laminate obtained in Examples were set on a sample holder therebetween. The straight line V was arranged so as to be a line on the anisotropic light diffusion film perpendicular to the tilt direction of the central axis of scattering.
Further, the incident side of the light from the light source is the irradiation surface side in the anisotropic light diffusion film, the laminate surface side in the anisotropic light diffusion film laminate, and the scattering center axis angle θ of the anisotropic light diffusion film having the laminate surface. It was set so that A was a positive value.
As shown in FIG. 6, the sample is rotated with the straight line V as the axis of rotation, the amount of linear transmitted light corresponding to each incident light angle is measured, the linear transmittance is calculated, the linear transmittance is plotted for each angle, An optical profile was created. With this evaluation method, it is possible to evaluate in which range of angles the incident light is diffused. The amount of linearly transmitted light was measured at a wavelength in the visible light region using a visibility filter.
Based on the optical profile obtained as a result of the above measurements, the maximum linear transmittance, which is the maximum value of the linear transmittance, and the incident light angle at the maximum linear transmittance were obtained.
In the case of an anisotropic light diffusion film having two scattering central axes, the incident light angle at which the light diffusion property is approximately symmetrical is an angle located on the positive side of 0° (between the minimum values of linear transmittance The angle of the central portion (the central portion of the diffusion region)) is obtained as the scattering central axis angle θ A of the scattering central axis A, and the angle located on the minus side of 0° (between the minimum values of the linear transmittance) The angle of the approximate central portion (the central portion of the diffusion region)) was obtained as the scattering central axis angle θ B of the scattering central axis B.
Furthermore, in the case of an anisotropic light diffusion film having one central scattering axis, the angle of incident light (substantially central portion sandwiched between the minimum values of linear transmittance (central portion of the diffusion region) at which the light diffusion property has approximately symmetry angle) was obtained as the scattering central axis angle θ A of the scattering central axis A.
In the case of an anisotropic light diffusion film having two scattering central axes, the minimum linear transmittance at the angle between the scattering central axis A and the plane normal of the anisotropic light diffusing film is Tmin A , the scattering central axis B, |Tmin A −Tmin B | was calculated by obtaining Tmin B and the minimum linear transmittance at the angle between the anisotropic light diffusion film and the normal to the plane.
Furthermore, in the case of an anisotropic light-diffusing film having one scattering central axis, the minimum linear transmittance at the angle between the scattering central axis and the plane normal of the anisotropic light-diffusing film was obtained as Tmin A.
＜柱状構造体のアスペクト比＞
　実施例で得られた異方性光拡散フィルムおよび異方性光拡散フィルム積層体の複数の柱状構造体の、柱軸に垂直な断面（紫外線照射時の照射光側）を光学顕微鏡で観察し、柱状領域における柱状構造体の長径ＬＡおよび短径ＳＡを測定した。平均長径ＬＡおよび平均短径ＳＡの算出には、任意の２０個の柱状構造体の平均値とした。また、求めた平均長径ＬＡおよび平均短径ＳＡに対し、平均長径ＬＡ／平均短径ＳＡをアスペクト比として算出した。 <Aspect Ratio of Columnar Structure>
A plurality of columnar structures of the anisotropic light-diffusing film and the anisotropic light-diffusing film laminate obtained in Examples were observed with an optical microscope for cross sections perpendicular to the columnar axis (irradiation light side during ultraviolet irradiation). A major axis LA and a minor axis SA of the columnar structure were measured. An average value of 20 arbitrary columnar structures was used to calculate the average major axis LA and average minor axis SA. Also, the average major axis LA/average minor axis SA was calculated as an aspect ratio with respect to the obtained average major axis LA and average minor axis SA.
＜ヘイズ値（Ｈｚ）＞
　ヘイズメーターＮＤＨ－２０００（日本電色工業社製）を用いてＪＩＳ　Ｋ７１３６－１：２０００に準拠し、実施例で得られた異方性光拡散フィルムおよび異方性光拡散フィルム積層体のヘイズ値の測定を行った。
　なお、光の入射側は、異方性光拡散フィルムでは照射表面、異方性光拡散フィルム積層体では、積層体表面とした。 <Haze value (Hz)>
Using a haze meter NDH-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), the haze values of the anisotropic light diffusion films and anisotropic light diffusion film laminates obtained in Examples were measured according to JIS K7136-1:2000. rice field.
The incident side of light was the irradiated surface for the anisotropic light diffusion film, and the surface of the laminate for the anisotropic light diffusion film laminate.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
＜＜評価＞＞
　引き続き、実施例で作製した異方性光拡散フィルム１～５および異方性光拡散フィルム積層体１～３を、表２に示す実施例１～５の異方性光拡散フィルム１～５および比較例１～３の異方性光拡散フィルム積層体１～３とし、以下の評価を行った。 <<Evaluation>>
Subsequently, the anisotropic light-diffusing films 1 to 5 and the anisotropic light-diffusing film laminates 1 to 3 prepared in Examples were used as the anisotropic light-diffusing films 1 to 5 of Examples 1 to 5 and the anisotropic light diffusion films 1 to 5 of Comparative Examples 1 to 3 shown in Table 2. Anisotropic light diffusion film laminates 1 to 3 were evaluated as follows.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
＜白輝度比＞
　実施例で得た異方性光拡散フィルムまたは異方性光拡散フィルム積層体を、ＴＮモードの液晶ディスプレイ表面に貼合した。より詳細には、液晶ディスプレイの平面を正面から見たときに右側となる３時の方位をφ＝０°とし、０時の方位をφ＝９０°、９時の方位をφ＝１８０°、６時の方位をφ＝２７０°とする。
　これに対し、実施例１～５の異方性光拡散フィルム１～５では、散乱中心軸Ａの傾斜方位をφ＝０°に合わせて積層貼合し、比較例１～３の異方性光拡散フィルム積層体１～３では積層体表面の散乱中心軸Ａの傾斜方位をφ＝０°に合わせて積層貼合した。
　続いて、視野角測定装置Ｃｏｎｏｍｅｔｅｒ８０（Ｗｅｓｔｂｏｒｏ社製）を用いて、液晶ディスプレイに白を表示したときの、液晶ディスプレイの法線方向に対する極角０～８０°の範囲における白輝度を測定した。
　液晶ディスプレイの法線方向（極角θ＝０°）である正面の白輝度と、ディスプレイ平面の左右方向（φ＝０°、１８０°）における視野角３０°および７０°（極角θ＝３０°および７０°）での白輝度とを測定し、対ブランク比との対比である白輝度比として表３にまとめた。
　なお、白輝度比は、液晶ディスプレイ表面に異方性光拡散フィルムまたは異方性光拡散フィルム積層体を貼合していない状態を１とする対ブランク比として算出した。 <White luminance ratio>
The anisotropic light-diffusing film or the anisotropic light-diffusing film laminate obtained in the example was attached to the surface of a TN mode liquid crystal display. More specifically, when the plane of the liquid crystal display is viewed from the front, the azimuth at 3 o'clock on the right side is φ = 0°, the azimuth at 0 o'clock is φ = 90°, the azimuth at 9 o'clock is φ = 180°, Assume that the azimuth at 6 o'clock is φ=270°.
On the other hand, in the anisotropic light diffusion films 1 to 5 of Examples 1 to 5, the tilt direction of the scattering central axis A was aligned with φ=0°, and the anisotropic light diffusion films of Comparative Examples 1 to 3 were laminated. In the bodies 1 to 3, the tilting direction of the scattering central axis A on the surface of the laminate was adjusted to φ=0° and laminated.
Subsequently, using a viewing angle measuring device Conometer 80 (manufactured by Westboro), white luminance was measured in a polar angle range of 0 to 80° with respect to the normal direction of the liquid crystal display when white was displayed on the liquid crystal display.
The white luminance at the front, which is the normal direction of the liquid crystal display (polar angle θ = 0°), and the viewing angles of 30° and 70° (polar angle θ = 30°) in the horizontal direction of the display plane (φ = 0°, 180°) and 70°) were measured and summarized in Table 3 as the white luminance ratio, which is a comparison with the blank ratio.
The white luminance ratio was calculated as a ratio to a blank, with 1 being the state in which the anisotropic light-diffusing film or the anisotropic light-diffusing film laminate was not attached to the surface of the liquid crystal display.
＜ぼけ＞
　白輝度の評価に用いた構成（液晶ディスプレイ表面に異方性光拡散フィルムまたは異方性光拡散フィルム積層体を貼合）において、液晶ディスプレイに白を表示させ、ルーペを用いて表面からＲＧＢの画素を確認した。 <bokeh>
In the configuration used for the evaluation of white luminance (an anisotropic light diffusion film or an anisotropic light diffusion film laminate was attached to the surface of the liquid crystal display), white was displayed on the liquid crystal display, and RGB pixels were confirmed from the surface using a loupe. .
＜＜評価基準＞＞
　白輝度およびぼけの評価基準は以下とした。 <<Evaluation Criteria>>
The evaluation criteria for white brightness and blur are as follows.
＜白輝度比評価基準＞
　極角θ＝０°または３０°のとき
　０．８以上：○
　０．８未満：×
　極角θ＝７０°のとき
　１．３０以上：○
　１．３０未満：× <Evaluation Criteria for White Luminance Ratio>
When the polar angle θ = 0° or 30° 0.8 or more: ○
Less than 0.8: ×
1.30 or more when polar angle θ = 70°: ○
Less than 1.30: ×
＜ぼけ評価基準＞
　ＲＧＢの画素が、その境界であるブラックマトリクスもくっきりと視認できるもの：◎
　ＲＧＢがそれぞれ識別できるもの：○
　少なくともＲＧＢの一部が混ざって見えるもの：× <Bokeh Evaluation Criteria>
The RGB pixels and the black matrix, which is the boundary between them, can be clearly seen: ◎
RGB can be identified respectively: ○
At least part of RGB looks mixed: ×
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
＜＜評価結果＞＞
　実施例１～５に示されるとおり、本発明の散乱中心軸を２つ有する異方性光拡散フィルムは、正面（極角θ＝０°）や、比較的浅い視野角（極角θ＝３０°）での液晶ディスプレイ平面の左右方向（φ＝０°、１８０°）の輝度低下を抑えつつ、深い視野角（極角θ＝７０°）において、当該正面および比較的浅い視野角よりも、輝度が向上していた。すなわち、相対する２方位への視野角拡大の効果が現れているといえる。また、同時に画像ボケも抑えられていた。
　一方、比較例１～３は、散乱中心軸を１つ有する異方性光拡散フィルムを２枚準備し、２枚の散乱中心軸が互い違いとなるよう、傾斜方位を１８０°ずらし、透明粘着を介して積層したものであるが、液晶ディスプレイの光が段階的に拡散されることで、左右の拡散性に差が生じてしまい、当該比較的浅い視野角又は深い視野角で、液晶ディスプレイ平面の左右方向いずれかの輝度が低くなってしまっていた。さらに比較例２および３では、当該正面の輝度が低下や、ぼけが強くなってしまった。
　また、本発明の異方性光拡散フィルム積層体は、比較例の異方性光拡散フィルム積層体よりも、１層で本評価結果をえることができるので、厚みやコストの観点からも、有利であるものと考える。 <<Evaluation result>>
As shown in Examples 1 to 5, the anisotropic light diffusion film having two scattering central axes of the present invention can be viewed from the front (polar angle θ = 0°) or at a relatively shallow viewing angle (polar angle θ = 30°). While suppressing the decrease in brightness in the horizontal direction (φ = 0 °, 180 °) of the liquid crystal display plane, at a deep viewing angle (polar angle θ = 70 °), the brightness is higher than the front and relatively shallow viewing angles. was improving. In other words, it can be said that the effect of widening the viewing angle in two opposite directions has appeared. At the same time, image blurring was also suppressed.
On the other hand, in Comparative Examples 1 to 3, two anisotropic light diffusion films having one scattering central axis were prepared, and the tilted orientation was shifted by 180° so that the scattering central axes of the two sheets were alternated. Although it is laminated, the light of the liquid crystal display is diffused step by step, causing a difference in diffusion between the left and right. The brightness of one of them had become low. Furthermore, in Comparative Examples 2 and 3, the front luminance decreased and the blur increased.
In addition, the anisotropic light-diffusing film laminate of the present invention is more advantageous in terms of thickness and cost than the anisotropic light-diffusing film laminate of the comparative example, since it is possible to obtain this evaluation result with a single layer. I think.
　本発明は、特定の拡散特性を有する拡散媒体として、特定の異方性光拡散フィルムを用いることで、本評価結果を得ることができたものと考えられる。 It is believed that the present invention was able to obtain this evaluation result by using a specific anisotropic light diffusion film as a diffusion medium with specific diffusion properties.
　従って、厚みやコストを抑えながら、上下又は左右等対称性を有する２方位への視野角拡大およびボケ抑制効果を有する異方性光拡散フィルムとすることができる。 Therefore, it is possible to obtain an anisotropic light diffusing film that has an enlarged viewing angle in two directions with vertical or horizontal symmetry and an effect of suppressing blurring, while suppressing thickness and cost.

Claims (6)

  1. 　光の入射角度により拡散性が変化する異方性光拡散フィルムであって、
    　前記異方性光拡散フィルムは、マトリックス領域と、前記マトリックス領域とは屈折率の異なる複数の柱状構造体である柱状領域とを有し、
    　前記異方性光拡散フィルムの法線角度を０°としたとき、０°超９０°未満の角度範囲に散乱中心軸Ａおよび散乱中心軸Ｂを有し、
    　前記散乱中心軸Ａの方位角φＡを０°としたとき、前記散乱中心軸Ｂの方位角φBは、１７０°～１９０°であり、
    　前記法線と、前記散乱中心軸Ａとのなす角度を散乱中心軸角度θＡとし、前記法線と前記散乱中心軸Ｂとのなす角度を散乱中心軸角度θＢとすると、θＢ＝θＡ±１０°であることを特徴とする、異方性光拡散フィルム。     An anisotropic light diffusion film whose diffusibility changes depending on the incident angle of light,
    The anisotropic light diffusion film has a matrix region and a columnar region that is a plurality of columnar structures having a different refractive index from the matrix region,
    When the normal angle of the anisotropic light diffusion film is 0°, the scattering central axis A and the scattering central axis B are in an angle range of more than 0° and less than 90°,
    When the azimuth angle φ A of the scattering central axis A is 0°, the azimuth angle φ B of the scattering central axis B is 170° to 190°,
    Let the angle formed by the normal line and the scattering center axis A be the scattering center axis angle θ A , and let the angle between the normal line and the scattering center axis B be the scattering center axis angle θ B , then θ B =θ A An anisotropic light-diffusing film characterized by ±10°.
  2. 　前記散乱中心軸Ａと法線との間の角度における極小直線透過率をＴｍｉｎＡとし、前記散乱中心軸Ｂと法線との間の角度における極小直線透過率をＴｍｉｎＢとすると、
    ｜ＴｍｉｎＡ－ＴｍｉｎＢ｜≦５パーセントポイント
    であることを特徴とする、請求項１に記載の異方性光拡散フィルム。     Let Tmin A be the minimum linear transmittance at the angle between the scattering central axis A and the normal, and Tmin B be the minimum linear transmittance at the angle between the scattering central axis B and the normal.
    The anisotropic light-diffusing film of claim 1, wherein |Tmin A - Tmin B |≤5 percentage points.
  3. 　前記散乱中心軸角度θＡが１０°～６０°であることを特徴とする、請求項１又は２に記載の異方性光拡散フィルム。 3. The anisotropic light-diffusing film according to claim 1, wherein the scattering central axis angle θ A is 10° to 60°.
  4. 　ヘイズ値が、４０％以上であることを特徴とする、請求項１～３のいずれか一項に記載の異方性光拡散フィルム。 The anisotropic light-diffusing film according to any one of claims 1 to 3, which has a haze value of 40% or more.
  5. 　前記複数の柱状構造体の配向方向に垂直な断面における短径と長径のアスペクト比が２未満であることを特徴とする、請求項１～４のいずれか一項に記載の異方性光拡散フィルム。 The anisotropic light-diffusing film according to any one of claims 1 to 4, characterized in that the aspect ratio of the minor axis to the major axis in a cross section perpendicular to the alignment direction of the plurality of columnar structures is less than 2.
  6. 　請求項１～５のいずれか一項に記載の異方性光拡散フィルムを含むことを特徴とする、表示装置。 A display device comprising the anisotropic light diffusion film according to any one of claims 1 to 5.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009116127A (en) * 2007-11-07 2009-05-28 Tomoegawa Paper Co Ltd Anisotropic diffusion medium and light source unit using the same
WO2014156420A1 (en) * 2013-03-29 2014-10-02 リンテック株式会社 Light diffusion film and light diffusion film manufacturing method
WO2015111523A1 (en) * 2014-01-21 2015-07-30 株式会社巴川製紙所 Anisotropic optical film
JP2017097357A (en) * 2016-12-19 2017-06-01 リンテック株式会社 Method for manufacturing light diffusion film

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009116127A (en) * 2007-11-07 2009-05-28 Tomoegawa Paper Co Ltd Anisotropic diffusion medium and light source unit using the same
WO2014156420A1 (en) * 2013-03-29 2014-10-02 リンテック株式会社 Light diffusion film and light diffusion film manufacturing method
WO2015111523A1 (en) * 2014-01-21 2015-07-30 株式会社巴川製紙所 Anisotropic optical film
JP2017097357A (en) * 2016-12-19 2017-06-01 リンテック株式会社 Method for manufacturing light diffusion film

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