WO2013008589A1 - Optical sheet, planar light source device, and transmission image display device - Google Patents

Optical sheet, planar light source device, and transmission image display device Download PDF

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Publication number
WO2013008589A1
WO2013008589A1 PCT/JP2012/065639 JP2012065639W WO2013008589A1 WO 2013008589 A1 WO2013008589 A1 WO 2013008589A1 JP 2012065639 W JP2012065639 W JP 2012065639W WO 2013008589 A1 WO2013008589 A1 WO 2013008589A1
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WO
WIPO (PCT)
Prior art keywords
resin
optical sheet
sheet
light
surface portion
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Application number
PCT/JP2012/065639
Other languages
French (fr)
Japanese (ja)
Inventor
規光 坂田
友紀 島田
豊博 濱松
Original Assignee
住友化学株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 住友化学株式会社 filed Critical 住友化学株式会社
Priority to CN201280034175.3A priority Critical patent/CN103688102A/en
Publication of WO2013008589A1 publication Critical patent/WO2013008589A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/302—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0058—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide
    • G02B6/0061—Means for improving the coupling-out of light from the light guide varying in density, size, shape or depth along the light guide to provide homogeneous light output intensity

Definitions

  • the present invention relates to an optical sheet, a surface light source device, and a transmissive image display device.
  • the optical sheet is used in a transmissive image display device that displays an image on the transmissive image display unit by illuminating the transmissive image display unit with planar light from the surface light source device.
  • the optical sheet is used for the generation of planar light, the control of the brightness of the generated light, the light collection, and the like.
  • a styrene resin that is a resin containing a styrene monomer unit is used in addition to an acrylic resin.
  • Patent Document 1 Japanese Patent Publication No. 2010-53365 discloses that a styrene resin can be molded into a plate shape and used as a light diffusion plate.
  • the present invention has been made in view of the above circumstances, and includes a styrene resin, an optical sheet that suppresses yellowness and suppresses deterioration of the resin due to ultraviolet irradiation, and a surface light source including the optical sheet.
  • An object of the present invention is to provide a device and a transmissive image display device.
  • One aspect of the present invention includes a resin sheet portion containing a styrene-based resin, and includes at least one of a first surface portion and a second surface portion opposite to the first surface portion in the thickness direction of the resin sheet portion.
  • One provides an optical sheet containing an ultraviolet absorber and a hindered amine light stabilizer.
  • the styrene resin is used for the optical sheet.
  • the optical sheet includes an ultraviolet absorber and a hindered amine light stabilizer in at least one of the first surface portion and the second surface portion. Therefore, deterioration of the resin due to ultraviolet irradiation can be suppressed. Further, the optical sheet contains a hindered amine light stabilizer in addition to the ultraviolet absorber, so that the content of the ultraviolet absorber can be reduced. Therefore, the yellowishness of the resin due to the ultraviolet absorber can be suppressed.
  • the resin sheet portion includes a first resin layer that includes a styrene resin and forms at least one of the first and second surface portions, and a second resin layer that includes the styrene resin.
  • the first resin layer is laminated on the second resin layer, the first resin layer includes an ultraviolet absorber and a hindered amine light stabilizer, and the second resin layer includes an ultraviolet absorber and a hindered amine light stabilizer. It is good also as an optical sheet which does not contain.
  • the resin sheet portion has two first resin layers, and the second resin layer is sandwiched between the two first resin layers in the thickness direction of the resin sheet portion.
  • One of the first resin layers may be an optical sheet that forms the first surface portion and the other forms the second surface portion.
  • the ultraviolet absorber and the hindered amine light stabilizer may be uniformly dispersed in the resin sheet portion.
  • the styrene resin may be a polystyrene resin or a resin containing a styrene monomer unit and a methyl methacrylate monomer unit.
  • Another aspect of the present invention is the above optical sheet, which is provided on the second surface portion side of the resin sheet portion of the optical sheet and has a reflecting portion that reflects light on the first surface portion side. And a light source unit that crosses the first surface part and the second surface part and supplies light to the side surface of the resin sheet part of the optical sheet.
  • optical sheet wherein an optical sheet that diffuses and emits light incident from the second surface portion of the resin sheet portion of the optical sheet from the first surface portion, and optical There is provided a surface light source device including a light source unit that supplies light to a second surface portion of a resin sheet unit included in a sheet.
  • a transmissive image display device comprising: a transmissive image display unit illuminated with planar light emitted from a surface portion.
  • optical sheet wherein an optical sheet that diffuses and emits light incident from the second surface portion of the resin sheet portion of the optical sheet from the first surface portion, and optical A light source unit that supplies light to the second surface portion of the resin sheet portion included in the sheet, and a transmission type that is provided on the first surface portion side and is illuminated with planar light emitted from the first surface portion And a transmissive image display device including the image display unit.
  • an optical sheet that suppresses yellowness and suppresses deterioration of the resin due to ultraviolet irradiation, and the optical sheet are provided.
  • a surface light source device and a transmissive image display device can be provided.
  • FIG. 1 is an end view showing an embodiment of a transmissive image display apparatus.
  • FIG. 2 is a cross-sectional view showing one embodiment of the optical sheet according to the present embodiment.
  • FIG. 3 is a schematic diagram illustrating one process of manufacturing the optical sheet according to the present embodiment.
  • FIG. 4 is a cross-sectional view showing another embodiment of the optical sheet according to this embodiment.
  • FIG. 5 is an end view showing another embodiment of the transmissive image display device.
  • the transmissive image display device 10 of FIG. 1 includes a transmissive image provided on the surface light source device 22 having the optical sheet 11 and the first surface portion (light emitting portion) 12b side of the resin sheet portion 12 of the optical sheet 11. And a display unit 18.
  • the arrangement direction of the surface light source device 22 and the transmissive image display unit 18 is referred to as the z direction.
  • two directions orthogonal to the z direction, which are orthogonal to each other, are referred to as an x direction and a y direction, respectively.
  • the transmissive image display unit 18 displays an image with light emitted from the surface light source device 22.
  • An example of the transmissive image display unit 18 is a liquid crystal display panel.
  • the transmissive image display device 10 is a liquid crystal display device (or a liquid crystal television).
  • a plurality of optical films 20 disposed between the optical sheet 11 and the transmissive image display unit 18 may be further provided.
  • the optical film 20 are a diffusion film, a prism film, and a brightness enhancement film.
  • the surface light source device 22 is an edge light type surface light source device 22 including an optical sheet 11 having a plate-shaped resin sheet portion 12 and a light source portion 14 disposed in the vicinity of a side surface 12 a of the resin sheet portion 12.
  • the surface light source device 22 may further include a reflecting member 16 disposed on the second surface portion (back surface portion) 12c side of the resin sheet portion 12.
  • An example of the reflecting member 16 is a reflecting sheet.
  • the reflecting member 16 may be a bottom surface of the casing of the surface light source device 22 that accommodates the optical sheet 11 and that is mirror-finished. By providing the reflecting member 16, the light emitted from the optical sheet 11 to the reflecting member 16 side can be returned to the optical sheet 11. As a result, the light from the light source unit 14 can be used more effectively.
  • the optical film 20 may be a component of the surface light source device 22.
  • the light source unit 14 includes a light source 14A.
  • the light source 14 ⁇ / b> A is provided along the y direction of the side surface 12 a of the resin sheet portion 12.
  • the side surface 12a is an incident surface.
  • the light source 14A may be a point light source such as a light emitting diode, a halogen lamp, or a tungsten lamp, or may be a linear light source such as a fluorescent tube.
  • An RGB type light emitting diode that emits red light, green light, and blue light is suitably used as the light source 14A.
  • the distance between the light source 14A and the side surface (incident surface) 12a of the resin sheet portion 12 is usually 1 mm to 15 mm, preferably 10 mm or less, more preferably 5 mm or less.
  • the light source 14A is a point light source
  • a plurality of point light sources are linearly arranged along the y direction of the side surface 12a.
  • the interval between adjacent point light sources is usually 1 mm to 25 mm. From the viewpoint of power saving, the distance between adjacent point light sources is preferably 10 mm or more so that the number of point light sources can be reduced.
  • the light source unit 14 may further include a reflector 14B that is provided on the side opposite to the optical sheet 11 and reflects light. By having the reflector 14B, the light from the light source 14A can be efficiently incident on the side surface 12a of the resin sheet portion 12.
  • the reflector 14B is formed from, for example, a white resin plate or a white resin film.
  • the light source unit 14 is provided on only one side surface among the four side surfaces of the resin sheet 12. However, the light source part 14 should just be provided in the side of the resin sheet part 12. FIG.
  • the light source part 14 may be provided with respect to each of a pair of side surfaces which the resin sheet part 12 opposes.
  • the light source unit 14 may be provided on all four side surfaces intersecting (orthogonal in FIG. 1) with the first surface unit 12b and the second surface unit 12c.
  • the optical sheet 11 is a light guide plate.
  • the optical sheet 11 has a resin sheet portion 12 and a reflection portion 24 provided on the second surface portion 12 c of the resin sheet portion 12.
  • the resin sheet portion 12 is a plate-like body having a substantially rectangular shape in plan view when viewed from the z direction.
  • the resin sheet portion 12 has a first surface portion 12b and a second surface portion 12c opposite to the first surface portion 12b in the thickness direction.
  • the “surface portion” refers to a range from the surface to a predetermined depth in the thickness direction.
  • the predetermined depth is, for example, 50 ⁇ m.
  • the thickness of the resin sheet portion 12 is preferably 1 mm to 30 mm, more preferably 1 mm to 10 mm.
  • the side surface 12a of the resin sheet portion 12 may be smoothed by a polishing process or the like.
  • the resin sheet portion 12 can be produced by a method that is usually employed as a method for molding a resin plate.
  • the resin sheet portion 12 can be produced by a hot press method, a melt extrusion method, an injection molding method, or the like.
  • the reflection part 24 is provided on the second surface part 12 c side of the resin sheet part 12.
  • the reflection part 24 reflects the light that has reached the second surface part 12c of the resin sheet part 12 toward the first surface part 12b.
  • a reflection dot is mentioned.
  • An example of the reflection dot is a diffusion dot.
  • the diffusing dots reflect the light propagating toward the second surface portion 12c while diffusing the light toward the first surface portion 12b.
  • the diffusing dots are typically white dots.
  • the diffusion dots are formed in a pattern designed to make the emitted light uniform.
  • the diffusing dots can be formed by, for example, screen printing or ink jet printing.
  • the reflection part 24 is not limited to a diffusing dot.
  • an uneven shape having a predetermined pattern is formed on the second surface portion 12 c, and the second surface portion 12 c having this uneven shape can be the reflecting portion 24.
  • a lens-shaped transparent or translucent dot may be provided on the second surface portion 12 c as the reflection portion 24.
  • the traveling direction of the light is changed by the effect of the lens, and the light can be emitted from the first surface portion 12b side.
  • the surface of the first surface portion 12 b opposite to the second surface portion 12 c is the emission surface of the optical sheet 11.
  • the resin sheet portion 12 is a laminated body (multilayer body) having a first resin layer 12d and a second resin layer 12e.
  • the first resin layer 12d and the second resin layer 12e are laminated in the order of the first resin layer 12d, the second resin layer 12e, and the first resin layer 12d. That is, the resin sheet portion 12 has a two-type three-layer structure in which the second resin layer 12e that is an intermediate layer is sandwiched between the first resin layers 12d that are surface layers.
  • One of the two first resin layers 12d forms the first surface portion 12b, and the other forms the second surface portion 12c.
  • An example of the thickness of the first resin layer 12d is 50 ⁇ m.
  • the first resin layer 12d and the second resin layer 12e are layers made of a styrene resin.
  • An example of the styrenic resin is polystyrene.
  • the content of the ultraviolet absorber in the first resin layer 12d is 0.5% by mass to 3.0% by mass based on the mass of the first resin layer 12d, and preferably 0.5% by mass to 2.0%. % By mass.
  • the content of the hindered amine light stabilizer in the first resin layer 12d is 0.1% by mass to 2.0% by mass based on the mass of the first resin layer 12d, and preferably 0.1% by mass to 1%. 0.5% by mass.
  • the content of the ultraviolet absorber in the second resin layer 12e is 0.1% by mass to 0.3% by mass based on the mass of the second resin layer 12e, and preferably 0.1% by mass to 0.2%. % By mass.
  • the ultraviolet absorber is not particularly limited as long as it is usually used.
  • UV absorbers include benzotriazole UV absorbers, malonic ester UV absorbers, cinnamic ester UV absorbers, cyanoacrylate UV absorbers, oxalanilide UV absorbers, and benzophenone UV absorbers.
  • Salicylate ultraviolet absorbers nickel complex ultraviolet absorbers
  • benzoate ultraviolet absorbers oxalic anilide ultraviolet absorbers and acetate ester ultraviolet absorbers.
  • a benzotriazole ultraviolet absorber is used.
  • the hindered amine light stabilizer is not particularly limited as long as it is usually used.
  • examples of hindered amine light stabilizers include “CHimasorb 119FL” manufactured by BASF Japan, “CHIMASORB 2020FDL” manufactured by the same company, “CHIMASORB 944FDL” manufactured by the same company, “CHIMASORB 622DL” manufactured by the same company, “Tinvin 123S” manufactured by the same company, “Tinvin 123S” manufactured by the same company, and “Tinvin 123S” manufactured by the same company 14 "Tinuvin 770DF” manufactured by the same company, “Tinvin XT850FF” manufactured by the same company, “Tinvin XT 855FF” manufactured by the same company, "LA-52” manufactured by ADEKA, "LA-57” manufactured by the same company, “LA-62” manufactured by the same company, “LA-62” manufactured by the same company Includes LA-67, LA-77Y, LA-82, LA-87, LA-63P.
  • the resin sheet portion 12 is within a range not departing from the gist of the present invention, and various additives such as a heat stabilizer, an antioxidant, a weathering agent, a bluing agent, a fluorescent whitening agent and a processing stabilizer, and light diffusion. Particles may be further included.
  • FIG. 3A is a diagram illustrating a schematic configuration of the manufacturing apparatus 40 for the resin sheet portion 12.
  • FIG. 3B is an enlarged view of a region b surrounded by a broken line in FIG.
  • the optical sheet 11 is manufactured by forming the resin sheet portion 12 by the manufacturing apparatus 40 shown in FIG.
  • 3A includes a first extruder 41 connected to the multi-manifold die 43 and a second extruder 42 also connected to the multi-manifold die 43.
  • the manufacturing apparatus 40 includes a first pressing roll 44, a second pressing roll 45, and a third pressing roll 46.
  • the 1st press roll 44, the 2nd press roll 45, and the 3rd press roll 46 are arrange
  • the surface of the 1st press roll 44, the 2nd press roll 45, and the 3rd press roll 46 is a mirror surface, respectively.
  • a styrene resin, a light diffusing agent, an ultraviolet absorber, a hindered amine light stabilizer, and a heat stabilizer are prepared.
  • a styrene resin, a light diffusing agent, and an ultraviolet absorber are blended (hand blended).
  • the obtained mixture (blended product) is melt-kneaded at 190 ° C. to 230 ° C. to produce a first master batch pellet.
  • the styrene resin, the light diffusing agent, the ultraviolet absorber, the hindered amine light stabilizer and the heat stabilizer are blended so that the concentrations of the ultraviolet absorber and the hindered amine light stabilizer are in the ranges exemplified above.
  • the melt-kneaded resin is supplied to the multi-manifold die 43.
  • the second master batch pellet is melt-kneaded by the second extruder 42 having a temperature in the cylinder of 200 ° C. to 245 ° C., and then the melt-kneaded resin is supplied to the multi-manifold die 43.
  • the resin supplied from the first extruder 41 is an intermediate layer (second resin layer 12e), and the resin supplied from the second extruder 42 is a surface layer (first resin layer 12d).
  • Co-extrusion molding is performed by the manifold die 43 at a die temperature of 245 ° C.
  • the coextruded resin is clamped and cooled by the first pressing roll 44, the second pressing roll 45, and the third pressing roll 46.
  • the resin sheet part 12 which is a laminated board having a two-type three-layer structure in which surface layers are provided on both sides of the intermediate layer as shown in FIG. 3B is obtained.
  • the thickness of the resin sheet portion 12 can be adjusted by adjusting the distance between the first pressing roll 44 and the second pressing roll 45 shown in FIG. By adjusting the distance between the second pressing roll 45 and the third pressing roll 46, the surface roughness of the surface of the resin sheet portion 12 can be adjusted.
  • a diffusion dot is formed on the second surface part 12c of the obtained resin sheet part 12 by screen printing or ink jet printing.
  • the optical sheet 11 is obtained.
  • the manufacturing method of the optical sheet 11 is not limited to this.
  • the optical sheet 11 in which the reflecting portion 24 is formed on the second surface portion 12c of the resin sheet portion 12 may be directly manufactured by injection molding or the like.
  • a pressing roll having a concavo-convex shape having a predetermined pattern is provided on the surface.
  • the optical sheet 11 may be directly produced.
  • the transparent dot or the semi-transparent dot can be formed in the same manner as the case of the diffusion dot.
  • manufacturing conditions such as temperature are exemplified, but the manufacturing conditions of the optical sheet 11 are not limited to the exemplified conditions.
  • the operation and effect of the resin sheet portion 12 according to the present embodiment will be described by taking as an example a case where it is applied to the transmissive image display device 10 as a part of the surface light source device 22, as shown in FIG.
  • the light source 14A of the light source unit 14 emits light
  • the light from the light source 14A enters the resin sheet unit 12 from the side surface 12a of the resin sheet unit 12 that faces the light source 14A.
  • the light incident on the resin sheet portion 12 propagates while totally reflecting inside the resin sheet portion 12.
  • a part of the light propagating through the resin sheet portion 12 is reflected by the reflecting portion 24 under conditions other than the light total reflection condition. Therefore, the light reflected by the reflecting portion 24 is emitted from the first surface portion 12b side. Thereby, the 1st surface part 12b can radiate
  • the resin sheet portion 12 included in the optical sheet 11 is a laminated body in which a first resin layer 12d and a second resin layer 12e are laminated.
  • the main component of the first resin layer 12d and the second resin layer 12e is a styrene resin. Therefore, the optical sheet 11 can be manufactured at low cost.
  • the first resin layer 12d constituting a part of the resin sheet portion 12 has an ultraviolet absorber of 0.5 mass% to 3.0 mass% and 0.1 mass% to 2 based on the mass of the first resin layer 12d. Contains 0% by weight of a hindered amine light stabilizer.
  • the resin sheet part 12 is comprised by making a styrene resin into a main component, deterioration of the resin resulting from ultraviolet irradiation can be suppressed.
  • the 1st resin layer 12d contains a hindered amine light stabilizer in addition to an ultraviolet absorber, the yellowishness of the 1st resin layer 12d by adding an ultraviolet absorber can be controlled. As a result, the transmissive image display device 10 including the optical sheet 11 can display an image with a color closer to nature.
  • the resin sheet portion 12 has a structure in which the first resin layer 12d as the surface layer is provided on both sides of the second resin layer 12e as the intermediate layer, the resin from the light source portion 14
  • the light incident on the side surface 12a of the sheet portion 12 mainly propagates through the second resin layer 12e.
  • a reduction in light transmittance can be further suppressed.
  • Ultraviolet rays are likely to enter the optical sheet 11 from the first surface portion 12 b side and the second surface portion 12 c side of the optical sheet 11 having a larger surface area in the optical sheet 11.
  • the first resin layer 12d containing the ultraviolet absorber and the hindered amine light stabilizer is disposed in the outermost layer in the laminated structure, so that deterioration of the resin due to ultraviolet irradiation is efficiently suppressed.
  • the transmissive image display device 10 including the optical sheet 11 can display an image with a more natural hue. Since only the first resin layer 12d contains the ultraviolet absorber and the hindered amine light stabilizer, the amount of the ultraviolet absorber and the hindered amine light stabilizer used in manufacturing the optical sheet 11 can be suppressed.
  • the surface light source device 22 includes an optical sheet 11 having a resin sheet portion 12. Therefore, the surface light source device 22 can emit planar light having a brightness close to that of natural colors.
  • the transmissive image display device 10 includes the optical sheet 11. Therefore, the transmissive image display apparatus 10 can display an image with a luminance that is close to natural and with a sufficient luminance.
  • the present invention is not limited to the embodiment described above.
  • the present invention can be modified as appropriate without departing from the spirit of the present invention.
  • the styrene resin that is the main component of the first resin layer 12d and the second resin layer 12e is not limited to the exemplified polystyrene, and may be a resin containing a styrene monomer unit.
  • the first resin layer 12d and the second resin layer 12e may be resins obtained by copolymerizing a styrene monomer and a (meth) acrylic acid ester, respectively.
  • (meth) acrylic acid ester is meant to include methacrylic acid ester and acrylic acid ester.
  • the main component of the first resin layer 12d or the second resin layer 12e is a resin obtained by copolymerizing a styrene monomer and a (meth) acrylic acid ester
  • the amount of the styrene monomer unit is ( It is preferable that it is more than the quantity of a meth) acrylic ester unit. That is, the resin constituting the first resin layer 12d and the second resin layer 12e has a styrene monomer unit content of 50% by mass to 100% by mass and a (meth) acrylic acid ester unit content. Resins that are 0% to 50% by weight are preferred.
  • a styrene-based resin is derived from a styrene-based monomer unit or is easily deteriorated by ultraviolet irradiation, the present invention is preferably applied.
  • An example of a resin in which such a styrene monomer and a (meth) acrylic acid ester monomer are copolymerized is a resin (MS resin) containing a styrene monomer unit and a methyl methacrylate monomer unit. is there.
  • substituted styrene or the like can be used in addition to styrene.
  • substituted styrene include halogenated styrene such as chlorostyrene and bromostyrene, and alkylstyrene such as vinyltoluene and ⁇ -methylstyrene.
  • (meth) acrylic acid esters include, in addition to methyl methacrylate, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate and 2-hydroxyethyl methacrylate.
  • acrylate esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate Can be mentioned.
  • the layer structure of the resin sheet portion 12 may be a two-layer structure having one first resin layer 12d and one second resin layer 12e as shown in FIG.
  • the first resin layer 12 d is the first surface portion 12 b of the resin sheet portion 12.
  • the first surface portion 12b of the resin sheet portion 12 is on the transmissive image display portion 18 side in FIG. 1, and is a region where the color of the resin tends to affect image display.
  • the second resin layer 12e may contain an ultraviolet absorber and a hindered amine light stabilizer.
  • the resin sheet portion 12 is not limited to a multilayer structure, and may be a single layer.
  • the first resin layer 12d and the second resin layer 12e contain the same styrene resin, and the concentration of the ultraviolet absorber and the hindered amine light stabilizer at the interface between the first resin layer 12d and the second resin layer 12e. May change step by step.
  • the ultraviolet absorber and the hindered amine light stabilizer may be uniformly dispersed in the resin sheet portion 12. Deterioration of the resin due to ultraviolet irradiation can be more reliably suppressed.
  • FIG. 5 is an end view showing another embodiment of the transmissive image display device.
  • the transmissive image display device 10 includes a transmissive image display unit 18 and a surface light source device 22 as a direct type backlight unit disposed on the back side (lower side) of the transmissive image display unit 18. .
  • the surface light source device 22 has a light source unit 14 including a plurality of light sources 14A arranged in parallel.
  • Each light source 14A is a linear light source 14A extending in a direction orthogonal to the arrangement direction of the plurality of light sources 14A.
  • An example of the light source 14A is a straight tubular light source such as a fluorescent lamp (cold cathode ray lamp).
  • the plurality of light sources 14A are arranged at intervals so that the central axes of the light sources 14A are located in the same plane.
  • the light source 14A is a linear light source, but a point light source such as an LED may be used.
  • the surface light source device 22 is a plate-like optical sheet (light diffusion) disposed on the front side of the light source unit 14 (upper side in FIG. 5), that is, on the transmissive image display unit 18 side and spaced from the light source 14A. Plate) 11.
  • Examples of the planar view shape of the resin sheet portion 12 include rectangular shapes such as a rectangle and a square.
  • the optical sheet 11 according to the present embodiment may be used as an optical film 20 such as a diffusion film, a prism film, and a brightness enhancement film.
  • the resin sheet as the resin sheet part 12 was manufactured with the manufacturing apparatus 40 shown to Fig.3 (a). With respect to 90.4 parts by mass of thermoplastic resin A, 8.0 parts by mass of light diffusing agent B, 1.0 part by mass of ultraviolet absorber B, 0.5 parts by mass of hindered amine light stabilizer, And 0.10 parts by mass of a heat stabilizer were dry blended. Thereafter, the blended product was put into a hopper of a granulator having a screw diameter of 30 mm ⁇ , and melt-kneaded at 190 ° C. to 230 ° C. to produce master batch pellets C.
  • 100 parts by mass of the master batch pellet C was melt-kneaded at 200 ° C. to 245 ° C. in the second extruder 42 (single screw extruder having a screw diameter of 20 mm ⁇ ).
  • 11 parts by mass of master batch pellet B and 89 parts by mass of thermoplastic resin A were blended (hand blended). Thereafter, the blended product was melt-kneaded at 200 ° C. to 245 ° C. in a first extruder 41 (single screw extruder having a screw diameter of 40 mm ⁇ ).
  • Each melt-kneaded resin was continuously coextruded from a multi-manifold die 43 having a width of 250 mm as a resin sheet having a two-kind / three-layer structure at a die temperature of 245 ° C.
  • the extruded resin sheet was pressed by the first pressing roll 44 and the second pressing roll 45 which are mirror surface cooling rolls. Thereafter, the resin sheet was conveyed along with the rotation of the second pressing roll 45 in a state of being in close contact with the second pressing roll 45. Next, the resin sheet was pressed by the second pressing roll 45 and the third pressing roll 46.
  • the resin sheet as the resin sheet part 12 of Example 1 which has the surface layer (1st resin layer 12d) containing a ultraviolet absorber and a hindered amine light stabilizer on both surfaces of the resin sheet was manufactured.
  • the thickness of the surface layer of the obtained resin sheet was 50 ⁇ m.
  • the plate thickness of the obtained resin sheet was 2.0 mm.
  • thermoplastic resin A 8.0 parts by mass of light diffusing agent B, 1.0 part by mass of ultraviolet absorber B, 1.0 part by mass of a hindered amine light stabilizer, 0.10 parts by weight of heat stabilizer was dry blended.
  • the blended product was put into a hopper of a granulator having a screw diameter of 30 mm ⁇ , and melt-kneaded at 190 ° C. to 230 ° C. to produce a master batch pellet D.
  • a resin sheet as the resin sheet portion 12 was produced in the same manner as in Example 1 except that the master batch pellet D was used instead of the master batch pellet C.
  • thermoplastic resin A 90.9 parts by mass of thermoplastic resin A, 8.0 parts by mass of light diffusing agent B, 1.0 part by mass of ultraviolet absorber B, and 0.10 parts by mass of thermal stabilizer are dry blended. It was done. The blended product was put into a hopper of a granulator having a screw diameter of 30 mm ⁇ , and melt-kneaded at 190 ° C. to 230 ° C., thereby producing a master batch pellet E.
  • a resin sheet was produced in the same manner as in Example 1 except that master batch pellet E was used instead of master batch pellet C.
  • thermoplastic resin A 8.0 parts by mass of light diffusing agent B, 2.5 parts by mass of ultraviolet absorber B, and 0.10 parts by mass of thermal stabilizer are dry blended. It was done. The blended product was put into a hopper of a granulator having a screw diameter of 30 mm ⁇ , and melt-kneaded at 190 ° C. to 230 ° C. to produce a master batch pellet F.
  • a resin sheet was produced in the same manner as in Example 1 except that the master batch pellet F was used instead of the master batch pellet C.
  • ⁇ Durability evaluation method> A sample for durability evaluation was attached at a position 20 cm away from a mercury lamp lamp (Iwasaki Electric, 400 W) of a mercury lamp irradiation apparatus (trade name PH-201, manufactured by ESPEC CORP.). The illuminance at the position where the sample for durability evaluation was attached was 1 mW / cm 2 . A sample for durability evaluation was taken out every predetermined time, and the yellowness (YI) of the sample for durability evaluation was measured. The same sample was used as a sample for durability evaluation. The yellowness of a sample for durability evaluation was measured every 0, 500, 1000, 1500 and 2000 hours with a spectrophotometer (trade name, U-4100, manufactured by Hitachi High-Technology Corporation).
  • the optical sheet according to the present invention is an optical sheet in which yellowness is suppressed and deterioration of the resin due to ultraviolet irradiation is suppressed.
  • SYMBOLS 10 Transmission type image display apparatus, 11 ... Optical sheet, 12 ... Resin sheet part, 12a ... Side surface, 12b ... 1st surface part (output part), 12c ... 2nd surface part (back part), 12d ... 1st DESCRIPTION OF SYMBOLS 1 resin layer, 12e ... 2nd resin layer, 14 ... Light source part, 16 ... Reflective member, 18 ... Transmission-type image display part, 20 ... Optical film part, 22 ... Surface light source device, 24 ... Reflection part (diffusion dot).

Abstract

Provided are an optical sheet, including a styrene resin, whereby yellowing is alleviated and resin degradation owing to ultraviolet illumination is alleviated, as well as a planar light source device and a transmission image display device comprising the optical sheet. The optical sheet (11) comprises a resin sheet unit (12) which includes the styrene resin. In the optical sheet (11), at least either a first obverse face part (12b) or a second obverse face part (12c) which is on the opposite side of the resin sheet (12) from the first obverse face part (12b) in the thickness direction of the resin sheet (12) includes an ultraviolet absorption agent and a hindered amine optical stability agent.

Description

光学シート、面光源装置及び透過型画像表示装置Optical sheet, surface light source device, and transmissive image display device
　本発明は、光学シート、面光源装置及び透過型画像表示装置に関する。 The present invention relates to an optical sheet, a surface light source device, and a transmissive image display device.
　光学シートは、面光源装置からの面状の光で透過型画像表示部を照明することによって、透過型画像表示部に画像を表示する透過型画像表示装置等に用いられている。具体的には光学シートは面状の光の生成、並びに、生成された光の輝度の制御及び集光等に利用されている。 The optical sheet is used in a transmissive image display device that displays an image on the transmissive image display unit by illuminating the transmissive image display unit with planar light from the surface light source device. Specifically, the optical sheet is used for the generation of planar light, the control of the brightness of the generated light, the light collection, and the like.
　光学シートを形成する透光性の材料としては、アクリル系樹脂のほか、スチレン系単量体単位を含む樹脂であるスチレン系樹脂が用いられている。特許文献１［特表２０１０－５３１３６５号公報］には、スチレン系樹脂が板状に成形され、光拡散板として用いられ得る旨が開示されている。 As the translucent material for forming the optical sheet, a styrene resin that is a resin containing a styrene monomer unit is used in addition to an acrylic resin. Patent Document 1 [Japanese Patent Publication No. 2010-53365] discloses that a styrene resin can be molded into a plate shape and used as a light diffusion plate.
特表２０１０－５３１３６５号公報Special table 2010-53365 gazette
　スチレン系樹脂を光学シートに用いた場合、紫外線照射による樹脂の劣化が起こり易い。その結果、光学シートが黄色く変色（黄変）する傾向がある。これに対処するために、スチレン系樹脂等に紫外線吸収剤を添加して光学シートを製造することが提案されている（特許文献１）。しかしながら、樹脂の劣化が抑制できるように紫外線吸収剤を樹脂に添加すると、紫外線吸収剤によって樹脂が黄色味を帯びてしまう傾向がある。この点において更なる改善が求められている。 When a styrene resin is used for an optical sheet, the resin is likely to be deteriorated by ultraviolet irradiation. As a result, the optical sheet tends to turn yellow (yellow). In order to cope with this, it has been proposed to manufacture an optical sheet by adding an ultraviolet absorber to a styrene resin or the like (Patent Document 1). However, when an ultraviolet absorber is added to the resin so that the deterioration of the resin can be suppressed, the resin tends to be yellowish by the ultraviolet absorber. There is a need for further improvements in this regard.
　本発明は、上記事情に鑑みてなされたものであり、スチレン系樹脂を含み、黄色味が抑制されるとともに紫外線照射による樹脂の劣化を抑制した光学シート、並びに、その光学シートを備えた面光源装置及び透過型画像表示装置を提供することを目的とする。 The present invention has been made in view of the above circumstances, and includes a styrene resin, an optical sheet that suppresses yellowness and suppresses deterioration of the resin due to ultraviolet irradiation, and a surface light source including the optical sheet. An object of the present invention is to provide a device and a transmissive image display device.
　本発明の一側面は、スチレン系樹脂を含む樹脂シート部を備え、第１の表面部及び、樹脂シート部の厚さ方向における第１の表面部と反対側の第２の表面部のうち少なくとも一方が、紫外線吸収剤とヒンダードアミン系光安定剤とを含む、光学シートを提供する。 One aspect of the present invention includes a resin sheet portion containing a styrene-based resin, and includes at least one of a first surface portion and a second surface portion opposite to the first surface portion in the thickness direction of the resin sheet portion. One provides an optical sheet containing an ultraviolet absorber and a hindered amine light stabilizer.
　上記光学シートは、スチレン系樹脂を用いている。上記光学シートは、紫外線吸収剤とヒンダードアミン系光安定剤とを、第１の表面部及び第２の表面部のうち少なくとも一方に含む。そのため、紫外線照射による樹脂の劣化が抑制され得る。さらに、上記光学シートは、紫外線吸収剤に加えてヒンダードアミン系光安定剤を含むことによって、紫外線吸収剤の含有量が少なくてすむ。そのため、紫外線吸収剤による樹脂の黄色味が抑えられる。 The styrene resin is used for the optical sheet. The optical sheet includes an ultraviolet absorber and a hindered amine light stabilizer in at least one of the first surface portion and the second surface portion. Therefore, deterioration of the resin due to ultraviolet irradiation can be suppressed. Further, the optical sheet contains a hindered amine light stabilizer in addition to the ultraviolet absorber, so that the content of the ultraviolet absorber can be reduced. Therefore, the yellowishness of the resin due to the ultraviolet absorber can be suppressed.
　本発明の一側面は、樹脂シート部が、スチレン系樹脂を含み第１及び第２の表面部のうち少なくとも一方を形成する第１樹脂層と、スチレン系樹脂を含む第２樹脂層とを備え、第１樹脂層は第２樹脂層に積層されており、第１樹脂層は紫外線吸収剤とヒンダードアミン系光安定剤とを含み、第２樹脂層は紫外線吸収剤とヒンダードアミン系光安定剤とを含まない光学シートとしてもよい。 In one aspect of the present invention, the resin sheet portion includes a first resin layer that includes a styrene resin and forms at least one of the first and second surface portions, and a second resin layer that includes the styrene resin. The first resin layer is laminated on the second resin layer, the first resin layer includes an ultraviolet absorber and a hindered amine light stabilizer, and the second resin layer includes an ultraviolet absorber and a hindered amine light stabilizer. It is good also as an optical sheet which does not contain.
　本発明の一側面は、樹脂シート部が２つの第１樹脂層を有し、樹脂シート部の厚さ方向において２つの第１樹脂層の間に第２樹脂層が挟まれており、２つの第１樹脂層の一方が第１の表面部を形成し、他方が第２の表面部を形成する光学シートとしてもよい。 In one aspect of the present invention, the resin sheet portion has two first resin layers, and the second resin layer is sandwiched between the two first resin layers in the thickness direction of the resin sheet portion. One of the first resin layers may be an optical sheet that forms the first surface portion and the other forms the second surface portion.
　本発明の一側面に係る光学シートでは、紫外線吸収剤とヒンダードアミン系光安定剤は、樹脂シート部中に均一に分散されていてもよい。 In the optical sheet according to one aspect of the present invention, the ultraviolet absorber and the hindered amine light stabilizer may be uniformly dispersed in the resin sheet portion.
　本発明の一側面に係る光学シートでは、スチレン系樹脂が、ポリスチレン樹脂又はスチレン単量体単位及びメタクリル酸メチル単量体単位を含む樹脂であってもよい。 In the optical sheet according to one aspect of the present invention, the styrene resin may be a polystyrene resin or a resin containing a styrene monomer unit and a methyl methacrylate monomer unit.
　本発明の別の側面は、上記光学シートであって、光学シートの樹脂シート部の第２の表面部側に設けられており第１の表面部側に光を反射する反射部を有する光学シートと、第１の表面部及び第２の表面部と交差しており、光学シートが有する樹脂シート部の側面に光を供給する光源部と、を備える面光源装置を提供する。 Another aspect of the present invention is the above optical sheet, which is provided on the second surface portion side of the resin sheet portion of the optical sheet and has a reflecting portion that reflects light on the first surface portion side. And a light source unit that crosses the first surface part and the second surface part and supplies light to the side surface of the resin sheet part of the optical sheet.
　本発明の別の側面は、上記光学シートであって、光学シートが有する樹脂シート部の第２の表面部から入射された光を第１の表面部から拡散して出射する光学シートと、光学シートが有する樹脂シート部の第２の表面部に光を供給する光源部と、を備える面光源装置を提供する。 Another aspect of the present invention is the optical sheet, wherein an optical sheet that diffuses and emits light incident from the second surface portion of the resin sheet portion of the optical sheet from the first surface portion, and optical There is provided a surface light source device including a light source unit that supplies light to a second surface portion of a resin sheet unit included in a sheet.
　本発明の別の側面は、上記光学シートであって、光学シートの樹脂シート部の第２の表面部側に設けられており第１の表面部側に光を反射する反射部を有する光学シートと、第１の表面部及び第２の表面部と交差しており、光学シートが有する樹脂シート部の側面に光を供給する光源部と、第１の表面部側に設けられ、第１の表面部から出射される面状の光で照明される透過型画像表示部と、を備える透過型画像表示装置を提供する。 Another aspect of the present invention is the above optical sheet, which is provided on the second surface portion side of the resin sheet portion of the optical sheet and has a reflecting portion that reflects light on the first surface portion side. And a first light source part that crosses the first surface part and the second surface part, supplies light to the side surface of the resin sheet part of the optical sheet, and is provided on the first surface part side. A transmissive image display device comprising: a transmissive image display unit illuminated with planar light emitted from a surface portion.
　本発明の別の側面は、上記光学シートであって、光学シートが有する樹脂シート部の第２の表面部から入射された光を第１の表面部から拡散して出射する光学シートと、光学シートが有する樹脂シート部の第２の表面部に光を供給する光源部と、第１の表面部側に設けられ、第１の表面部から出射される面状の光で照明される透過型画像表示部と、を備える透過型画像表示装置を提供する。 Another aspect of the present invention is the optical sheet, wherein an optical sheet that diffuses and emits light incident from the second surface portion of the resin sheet portion of the optical sheet from the first surface portion, and optical A light source unit that supplies light to the second surface portion of the resin sheet portion included in the sheet, and a transmission type that is provided on the first surface portion side and is illuminated with planar light emitted from the first surface portion And a transmissive image display device including the image display unit.
　本発明によれば、スチレン系単量体を含む樹脂を用いた場合であっても、黄色味が抑制されるとともに紫外線照射による樹脂の劣化を抑制した光学シート、並びに、その光学シートを備えた面光源装置及び透過型画像表示装置を提供することができる。 According to the present invention, even when a resin containing a styrene monomer is used, an optical sheet that suppresses yellowness and suppresses deterioration of the resin due to ultraviolet irradiation, and the optical sheet are provided. A surface light source device and a transmissive image display device can be provided.
図１は、透過型画像表示装置の一実施形態を示す端面図である。FIG. 1 is an end view showing an embodiment of a transmissive image display apparatus. 図２は、本実施形態に係る光学シートの一実施形態を示す断面図である。FIG. 2 is a cross-sectional view showing one embodiment of the optical sheet according to the present embodiment. 図３は、本実施形態に係る光学シートの作製の一工程を示す模式図である。FIG. 3 is a schematic diagram illustrating one process of manufacturing the optical sheet according to the present embodiment. 図４は、本実施形態に係る光学シートの他の実施形態を示す断面図である。FIG. 4 is a cross-sectional view showing another embodiment of the optical sheet according to this embodiment. 図５は、透過型画像表示装置の他の実施形態を示す端面図である。FIG. 5 is an end view showing another embodiment of the transmissive image display device.
　以下、図面を参照して、本発明の光学シート、面光源装置及び透過型画像表示装置の実施形態が説明される。図面の説明において、同一の要素には同一の符号が付され、重複する説明が省略される。図面の寸法比率は、説明の寸法比率と必ずしも一致していない。 Hereinafter, embodiments of an optical sheet, a surface light source device, and a transmissive image display device of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. The dimensional ratios in the drawings do not necessarily match the dimensional ratios in the description.
　図１の透過型画像表示装置１０は、光学シート１１を有する面光源装置２２と、光学シート１１が有する樹脂シート部１２の第１の表面部（出射部）１２ｂ側に設けられた透過型画像表示部１８とを有する。以下の説明では、図１に示されるように、面光源装置２２と透過型画像表示部１８の配列方向がｚ方向と称される。図１に示すように、ｚ方向に直交する２方向であって、互いに直交する２方向がそれぞれｘ方向及びｙ方向と称される。 The transmissive image display device 10 of FIG. 1 includes a transmissive image provided on the surface light source device 22 having the optical sheet 11 and the first surface portion (light emitting portion) 12b side of the resin sheet portion 12 of the optical sheet 11. And a display unit 18. In the following description, as shown in FIG. 1, the arrangement direction of the surface light source device 22 and the transmissive image display unit 18 is referred to as the z direction. As shown in FIG. 1, two directions orthogonal to the z direction, which are orthogonal to each other, are referred to as an x direction and a y direction, respectively.
　透過型画像表示部１８は、面光源装置２２から出射される光によって画像を表示する。透過型画像表示部１８の例は、液晶表示パネルである。この場合、透過型画像表示装置１０は、液晶表示装置（又は液晶テレビ）である。 The transmissive image display unit 18 displays an image with light emitted from the surface light source device 22. An example of the transmissive image display unit 18 is a liquid crystal display panel. In this case, the transmissive image display device 10 is a liquid crystal display device (or a liquid crystal television).
　光学シート１１と透過型画像表示部１８との間に配置された複数の光学フィルム２０が更に備えられてもよい。光学フィルム２０の例は、拡散フィルム、プリズムフィルム及び輝度向上フィルムである。 A plurality of optical films 20 disposed between the optical sheet 11 and the transmissive image display unit 18 may be further provided. Examples of the optical film 20 are a diffusion film, a prism film, and a brightness enhancement film.
　面光源装置２２は、板状の樹脂シート部１２を有する光学シート１１と、樹脂シート部１２の側面１２ａの近傍に配置された光源部１４とを備えるエッジライト方式の面光源装置２２である。面光源装置２２は、樹脂シート部１２の第２の表面部（背面部）１２ｃ側に配置された反射部材１６を更に備えてもよい。反射部材１６の例は、反射シートである。反射部材１６は、光学シート１１を収容する面光源装置２２の筐体底面であって、鏡面加工を施された底面であってもよい。反射部材１６を備えることで、光学シート１１から反射部材１６側に出射された光が光学シート１１に戻され得る。その結果、光源部１４からの光がより有効に利用され得る。上記光学フィルム２０は、面光源装置２２の構成要素であってもよい。 The surface light source device 22 is an edge light type surface light source device 22 including an optical sheet 11 having a plate-shaped resin sheet portion 12 and a light source portion 14 disposed in the vicinity of a side surface 12 a of the resin sheet portion 12. The surface light source device 22 may further include a reflecting member 16 disposed on the second surface portion (back surface portion) 12c side of the resin sheet portion 12. An example of the reflecting member 16 is a reflecting sheet. The reflecting member 16 may be a bottom surface of the casing of the surface light source device 22 that accommodates the optical sheet 11 and that is mirror-finished. By providing the reflecting member 16, the light emitted from the optical sheet 11 to the reflecting member 16 side can be returned to the optical sheet 11. As a result, the light from the light source unit 14 can be used more effectively. The optical film 20 may be a component of the surface light source device 22.
　光源部１４は、光源１４Ａを有する。光源１４Ａは、樹脂シート部１２の側面１２ａのｙ方向に沿って設けられる。側面１２ａは、入射面である。光源１４Ａは、発光ダイオード、ハロゲンランプ及びタングステンランプ等の点光源であってもよいし、蛍光管等の線状光源であってもよい。赤色光、緑色光及び青色光を発光するＲＧＢタイプの発光ダイオードが、光源１４Ａとして好適に用いられる。 The light source unit 14 includes a light source 14A. The light source 14 </ b> A is provided along the y direction of the side surface 12 a of the resin sheet portion 12. The side surface 12a is an incident surface. The light source 14A may be a point light source such as a light emitting diode, a halogen lamp, or a tungsten lamp, or may be a linear light source such as a fluorescent tube. An RGB type light emitting diode that emits red light, green light, and blue light is suitably used as the light source 14A.
　光源１４Ａと樹脂シート部１２の側面（入射面）１２ａとの距離は、通常１ｍｍ～１５ｍｍであり、好ましくは１０ｍｍ以下、より好ましくは５ｍｍ以下である。光源１４Ａが点光源である場合、側面１２ａのｙ方向に沿って複数の点光源が直線状に配列される。隣り合う点光源同士の間隔は、通常１ｍｍ～２５ｍｍである。省電力化の観点から、隣り合う点光源同士の間隔は、点光源の数を減らせるように好ましくは１０ｍｍ以上である。 The distance between the light source 14A and the side surface (incident surface) 12a of the resin sheet portion 12 is usually 1 mm to 15 mm, preferably 10 mm or less, more preferably 5 mm or less. When the light source 14A is a point light source, a plurality of point light sources are linearly arranged along the y direction of the side surface 12a. The interval between adjacent point light sources is usually 1 mm to 25 mm. From the viewpoint of power saving, the distance between adjacent point light sources is preferably 10 mm or more so that the number of point light sources can be reduced.
　光源部１４は、光学シート１１と反対側に設けられた、光を反射させるリフレクター１４Ｂを更に有していてもよい。リフレクター１４Ｂを有することにより、光源１４Ａからの光が効率良く樹脂シート部１２の側面１２ａに入射され得る。リフレクター１４Ｂは、例えば、白色樹脂板又は白色樹脂フィルムから形成される。 The light source unit 14 may further include a reflector 14B that is provided on the side opposite to the optical sheet 11 and reflects light. By having the reflector 14B, the light from the light source 14A can be efficiently incident on the side surface 12a of the resin sheet portion 12. The reflector 14B is formed from, for example, a white resin plate or a white resin film.
　図１に示された面光源装置２２においては、樹脂シート部１２の４つの側面のうち１つの側面のみに光源部１４が設けられている。しかしながら、光源部１４は、樹脂シート部１２の側方に設けられていればよい。例えば、樹脂シート部１２の対向する一対の側面それぞれに対して光源部１４が設けられてもよい。第１の表面部１２ｂ及び第２の表面部１２ｃと交差する（図１では直交する）４つの側面全てに対して光源部１４が設けられてもよい。 In the surface light source device 22 shown in FIG. 1, the light source unit 14 is provided on only one side surface among the four side surfaces of the resin sheet 12. However, the light source part 14 should just be provided in the side of the resin sheet part 12. FIG. For example, the light source part 14 may be provided with respect to each of a pair of side surfaces which the resin sheet part 12 opposes. The light source unit 14 may be provided on all four side surfaces intersecting (orthogonal in FIG. 1) with the first surface unit 12b and the second surface unit 12c.
　光学シート１１は導光板である。光学シート１１は樹脂シート部１２と、樹脂シート部１２の第２の表面部１２ｃに設けられた反射部２４を有する。 The optical sheet 11 is a light guide plate. The optical sheet 11 has a resin sheet portion 12 and a reflection portion 24 provided on the second surface portion 12 c of the resin sheet portion 12.
　樹脂シート部１２は、ｚ方向から見た場合の平面視形状が略矩形の板状体である。樹脂シート部１２は、第１の表面部１２ｂ及び厚さ方向において、第１の表面部１２ｂと反対側の第２の表面部１２ｃを有する。このとき「表面部」とは、厚さ方向において表面から所定の深さまでの範囲をいう。上記所定の深さは例えば、５０μｍである。 The resin sheet portion 12 is a plate-like body having a substantially rectangular shape in plan view when viewed from the z direction. The resin sheet portion 12 has a first surface portion 12b and a second surface portion 12c opposite to the first surface portion 12b in the thickness direction. In this case, the “surface portion” refers to a range from the surface to a predetermined depth in the thickness direction. The predetermined depth is, for example, 50 μm.
　樹脂シート部１２の厚さは、好ましくは１ｍｍ～３０ｍｍ、より好ましくは１ｍｍ～１０ｍｍである。樹脂シート部１２の側面１２ａは、研磨処理等により平滑化されていてもよい。樹脂シート部１２は、樹脂板の成形方法として通常採用されている方法により作製され得る。例えば、樹脂シート部１２は、熱プレス法、溶融押出法、射出成型法等により作製され得る。 The thickness of the resin sheet portion 12 is preferably 1 mm to 30 mm, more preferably 1 mm to 10 mm. The side surface 12a of the resin sheet portion 12 may be smoothed by a polishing process or the like. The resin sheet portion 12 can be produced by a method that is usually employed as a method for molding a resin plate. For example, the resin sheet portion 12 can be produced by a hot press method, a melt extrusion method, an injection molding method, or the like.
　反射部２４は、樹脂シート部１２の第２の表面部１２ｃ側に設けられる。反射部２４は、樹脂シート部１２の第２の表面部１２ｃに到達した光を第１の表面部１２ｂ側に反射させる。反射部２４としては、反射ドットが挙げられる。反射ドットの一例は、拡散ドットである。拡散ドットは、第２の表面部１２ｃ側に向けて伝搬してきた光を第１の表面部１２ｂ側に拡散させながら反射する。拡散ドットは、典型的には白色ドットである。拡散ドットは、出射光が均一になるように設計されたパターンで形成される。拡散ドットは、例えば、スクリーン印刷又はインクジェット印刷により形成され得る。 The reflection part 24 is provided on the second surface part 12 c side of the resin sheet part 12. The reflection part 24 reflects the light that has reached the second surface part 12c of the resin sheet part 12 toward the first surface part 12b. As the reflection part 24, a reflection dot is mentioned. An example of the reflection dot is a diffusion dot. The diffusing dots reflect the light propagating toward the second surface portion 12c while diffusing the light toward the first surface portion 12b. The diffusing dots are typically white dots. The diffusion dots are formed in a pattern designed to make the emitted light uniform. The diffusing dots can be formed by, for example, screen printing or ink jet printing.
　反射部２４は、拡散ドットに限定されない。例えば、第２の表面部１２ｃに所定のパターンを有する凹凸形状を形成し、この凹凸形状を有する第２の表面部１２ｃが反射部２４であり得る。レンズ形状の透明又は半透明のドットが、反射部２４として第２の表面部１２ｃ上に設けられてもよい。レンズの効果により光の進行方向が変えられて、光が第１の表面部１２ｂ側から出射され得る。この場合、第１の表面部１２ｂの第２の表面部１２ｃと反対側の面が光学シート１１の出射面である。 The reflection part 24 is not limited to a diffusing dot. For example, an uneven shape having a predetermined pattern is formed on the second surface portion 12 c, and the second surface portion 12 c having this uneven shape can be the reflecting portion 24. A lens-shaped transparent or translucent dot may be provided on the second surface portion 12 c as the reflection portion 24. The traveling direction of the light is changed by the effect of the lens, and the light can be emitted from the first surface portion 12b side. In this case, the surface of the first surface portion 12 b opposite to the second surface portion 12 c is the emission surface of the optical sheet 11.
　次に、樹脂シート部１２の構成が、図２を利用して詳細に説明される。樹脂シート部１２は、第１樹脂層１２ｄ及び第２樹脂層１２ｅを有する積層体（多層体）である。第１樹脂層１２ｄ及び第２樹脂層１２ｅは、第１樹脂層１２ｄ、第２樹脂層１２ｅ及び第１樹脂層１２ｄの順に積層されている。すなわち、樹脂シート部１２は、中間層である第２樹脂層１２ｅが表層である第１樹脂層１２ｄによって挟まれた２種３層の構造を有する。２つの第１樹脂層１２ｄの一方は第１の表面部１２ｂを形成し、他方が第２の表面部１２ｃを形成する。第１樹脂層１２ｄの厚さの例は、５０μｍである。 Next, the configuration of the resin sheet portion 12 will be described in detail with reference to FIG. The resin sheet portion 12 is a laminated body (multilayer body) having a first resin layer 12d and a second resin layer 12e. The first resin layer 12d and the second resin layer 12e are laminated in the order of the first resin layer 12d, the second resin layer 12e, and the first resin layer 12d. That is, the resin sheet portion 12 has a two-type three-layer structure in which the second resin layer 12e that is an intermediate layer is sandwiched between the first resin layers 12d that are surface layers. One of the two first resin layers 12d forms the first surface portion 12b, and the other forms the second surface portion 12c. An example of the thickness of the first resin layer 12d is 50 μm.
　第１樹脂層１２ｄ及び第２樹脂層１２ｅは、スチレン系樹脂で構成される層である。スチレン系樹脂の例は、ポリスチレンである。第１樹脂層１２ｄにおける紫外線吸収剤の含有量は、第１樹脂層１２ｄの質量を基準として０．５質量％～３．０質量％であり、好ましくは、０．５質量％～２．０質量％である。第１樹脂層１２ｄにおけるヒンダードアミン系光安定剤の含有量は、第１樹脂層１２ｄの質量を基準として０．１質量％～２．０質量％であり、好ましくは、０．１質量％～１．５質量％である。第２樹脂層１２ｅにおける紫外線吸収剤の含有量は、第２樹脂層１２ｅの質量を基準として０．１質量％～０．３質量％であり、好ましくは、０．１質量％～０．２質量％である。 The first resin layer 12d and the second resin layer 12e are layers made of a styrene resin. An example of the styrenic resin is polystyrene. The content of the ultraviolet absorber in the first resin layer 12d is 0.5% by mass to 3.0% by mass based on the mass of the first resin layer 12d, and preferably 0.5% by mass to 2.0%. % By mass. The content of the hindered amine light stabilizer in the first resin layer 12d is 0.1% by mass to 2.0% by mass based on the mass of the first resin layer 12d, and preferably 0.1% by mass to 1%. 0.5% by mass. The content of the ultraviolet absorber in the second resin layer 12e is 0.1% by mass to 0.3% by mass based on the mass of the second resin layer 12e, and preferably 0.1% by mass to 0.2%. % By mass.
　紫外線吸収剤は通常用いられているものであれば特に制限されない。紫外線吸収剤の例は、ベンゾトリアゾール系紫外線吸収剤、マロン酸エステル系紫外線吸収剤、桂皮酸エステル系紫外線吸収剤、シアノアクリレート系紫外線吸収剤、オキサルアニリド系紫外線吸収剤、ベンゾフェノン系紫外線吸収剤、サリチレート系紫外線吸収剤、ニッケル錯塩系紫外線吸収剤、ベンゾエート系紫外線吸収剤、シュウ酸アニリド系紫外線吸収剤及び酢酸エステル系紫外線吸収剤を含む。好ましくは、ベンゾトリアゾール系紫外線吸収剤が用いられる。 The ultraviolet absorber is not particularly limited as long as it is usually used. Examples of UV absorbers include benzotriazole UV absorbers, malonic ester UV absorbers, cinnamic ester UV absorbers, cyanoacrylate UV absorbers, oxalanilide UV absorbers, and benzophenone UV absorbers. , Salicylate ultraviolet absorbers, nickel complex ultraviolet absorbers, benzoate ultraviolet absorbers, oxalic anilide ultraviolet absorbers and acetate ester ultraviolet absorbers. Preferably, a benzotriazole ultraviolet absorber is used.
　ヒンダードアミン系光安定剤は通常用いられているものであれば特に制限されない。ヒンダードアミン系光安定剤の例は、ＢＡＳＦジャパン製「ＣＨｉｍａｓｓｏｒｂ１１９ＦＬ」、同社製「ＣＨｉｍａｓｓｏｒｂ２０２０ＦＤＬ」、同社製「ＣＨｉｍａｓｓｏｒｂ９４４ＦＤＬ」、同社製「ＣＨｉｍａｓｓｏｒｂ６２２ＤＬ」、同社製「Ｔｉｎｕｖｉｎ１２３Ｓ」、同社製「Ｔｉｎｕｖｉｎ１４４」、同社製「Ｔｉｎｕｖｉｎ７６５」、同社製「Ｔｉｎｕｖｉｎ７７０ＤＦ」、同社製「ＴｉｎｕｖｉｎＸＴ８５０ＦＦ」、同社製「ＴｉｎｕｖｉｎＸＴ８５５ＦＦ」の他、ＡＤＥＫＡ社製「ＬＡ－５２」、同社製「ＬＡ－５７」、同社製「ＬＡ－６２」、同社製「ＬＡ－６７」、同社製「ＬＡ－７７Ｙ」、同社製「ＬＡ－８２」、同社製「ＬＡ－８７」、同社製「ＬＡ－６３Ｐ」等を含む。 The hindered amine light stabilizer is not particularly limited as long as it is usually used. Examples of hindered amine light stabilizers include “CHimasorb 119FL” manufactured by BASF Japan, “CHIMASORB 2020FDL” manufactured by the same company, “CHIMASORB 944FDL” manufactured by the same company, “CHIMASORB 622DL” manufactured by the same company, “Tinvin 123S” manufactured by the same company, “Tinvin 123S” manufactured by the same company, and “Tinvin 123S” manufactured by the same company 14 "Tinuvin 770DF" manufactured by the same company, "Tinvin XT850FF" manufactured by the same company, "Tinvin XT 855FF" manufactured by the same company, "LA-52" manufactured by ADEKA, "LA-57" manufactured by the same company, "LA-62" manufactured by the same company, "LA-62" manufactured by the same company Includes LA-67, LA-77Y, LA-82, LA-87, LA-63P.
　樹脂シート部１２は、本発明の趣旨を逸脱しない範囲内において、熱安定剤、酸化防止剤、耐候剤、ブルーイング剤、蛍光増白剤及び加工安定剤等の各種添加剤、並びに、光拡散粒子を更に含んでもよい。 The resin sheet portion 12 is within a range not departing from the gist of the present invention, and various additives such as a heat stabilizer, an antioxidant, a weathering agent, a bluing agent, a fluorescent whitening agent and a processing stabilizer, and light diffusion. Particles may be further included.
　本実施形態に係る光学シート１１の作製方法の一例が、光学シート１１の作製の一工程を示す図３を利用して説明される。図３（ａ）は、樹脂シート部１２の製造装置４０の概略構成を示す図である。図３（ｂ）は、図３（ａ）の破線で囲まれた領域ｂの拡大図である。光学シート１１は、図３（ａ）に示す製造装置４０で樹脂シート部１２を作製した後、反射部２４としての拡散ドットを形成して作製される。 An example of a method for producing the optical sheet 11 according to the present embodiment will be described with reference to FIG. FIG. 3A is a diagram illustrating a schematic configuration of the manufacturing apparatus 40 for the resin sheet portion 12. FIG. 3B is an enlarged view of a region b surrounded by a broken line in FIG. The optical sheet 11 is manufactured by forming the resin sheet portion 12 by the manufacturing apparatus 40 shown in FIG.
　製造装置４０の構成が説明される。図３（ａ）に示す製造装置４０は、マルチマニホールドダイ４３に接続される第１押出機４１と、同じくマルチマニホールドダイ４３に接続される第２押出機４２とを備える。マルチマニホールドダイ４３から押し出される樹脂シートを成形するために、製造装置４０は、第一押圧ロール４４と、第二押圧ロール４５と、第三押圧ロール４６とを備える。第一押圧ロール４４、第二押圧ロール４５及び第三押圧ロール４６は、各ロールの軸が略平行になるように配置されている。第一押圧ロール４４、第二押圧ロール４５及び第三押圧ロール４６の表面はそれぞれ鏡面である。 The configuration of the manufacturing apparatus 40 will be described. 3A includes a first extruder 41 connected to the multi-manifold die 43 and a second extruder 42 also connected to the multi-manifold die 43. In order to mold the resin sheet extruded from the multi-manifold die 43, the manufacturing apparatus 40 includes a first pressing roll 44, a second pressing roll 45, and a third pressing roll 46. The 1st press roll 44, the 2nd press roll 45, and the 3rd press roll 46 are arrange | positioned so that the axis | shaft of each roll may become substantially parallel. The surface of the 1st press roll 44, the 2nd press roll 45, and the 3rd press roll 46 is a mirror surface, respectively.
　次に、光学シート１１の製造工程が説明される。まず、スチレン系樹脂、光拡散剤、紫外線吸収剤、ヒンダードアミン系光安定剤及び熱安定剤が準備される。次いで、スチレン系樹脂、光拡散剤及び紫外線吸収剤がブレンド（ハンドブレンド）される。得られた混合物（ブレンドした物）を１９０℃～２３０℃で溶融混練することによって、第１マスターバッチペレットが作製される。一方、スチレン系樹脂、光拡散剤、紫外線吸収剤、ヒンダードアミン系光安定剤及び熱安定剤は、紫外線吸収剤及びヒンダードアミン系光安定剤の濃度が上記例示した範囲となるようにブレンドされる。得られた混合物（ブレンドした物）を１９０℃～２３０℃で溶融混練することによって、第２マスターバッチペレットが作製される。 Next, the manufacturing process of the optical sheet 11 will be described. First, a styrene resin, a light diffusing agent, an ultraviolet absorber, a hindered amine light stabilizer, and a heat stabilizer are prepared. Subsequently, a styrene resin, a light diffusing agent, and an ultraviolet absorber are blended (hand blended). The obtained mixture (blended product) is melt-kneaded at 190 ° C. to 230 ° C. to produce a first master batch pellet. On the other hand, the styrene resin, the light diffusing agent, the ultraviolet absorber, the hindered amine light stabilizer and the heat stabilizer are blended so that the concentrations of the ultraviolet absorber and the hindered amine light stabilizer are in the ranges exemplified above. By melting and kneading the obtained mixture (blended product) at 190 ° C. to 230 ° C., a second master batch pellet is produced.
　スチレン系樹脂及び上記第１マスターバッチペレットをシリンダー内の温度が２００℃～２４５℃の第１押出機４１で溶融混練した後、溶融混練された樹脂がマルチマニホールドダイ４３に供給される。同様に、上記第２マスターバッチペレットを、シリンダー内の温度が２００℃～２４５℃の第２押出機４２で溶融混練した後、溶融混練された樹脂がマルチマニホールドダイ４３に供給される。 After the styrene-based resin and the first master batch pellet are melt-kneaded by the first extruder 41 having a temperature in the cylinder of 200 ° C. to 245 ° C., the melt-kneaded resin is supplied to the multi-manifold die 43. Similarly, the second master batch pellet is melt-kneaded by the second extruder 42 having a temperature in the cylinder of 200 ° C. to 245 ° C., and then the melt-kneaded resin is supplied to the multi-manifold die 43.
　そして、上記第１押出機４１から供給される樹脂が中間層（第２樹脂層１２ｅ）となり、上記第２押出機４２から供給される樹脂が表層（第１樹脂層１２ｄ）となるようにマルチマニホールドダイ４３によりダイ温度２４５℃で共押出成形が行われる。共押出成形された樹脂が第一押圧ロール４４、第二押圧ロール４５及び第三押圧ロール４６によって挟圧されると共に冷却される。その結果、図３（ｂ）に示されるような中間層の両側に表層が設けられた２種３層の構造を有する積層板である樹脂シート部１２が得られる。 The resin supplied from the first extruder 41 is an intermediate layer (second resin layer 12e), and the resin supplied from the second extruder 42 is a surface layer (first resin layer 12d). Co-extrusion molding is performed by the manifold die 43 at a die temperature of 245 ° C. The coextruded resin is clamped and cooled by the first pressing roll 44, the second pressing roll 45, and the third pressing roll 46. As a result, the resin sheet part 12 which is a laminated board having a two-type three-layer structure in which surface layers are provided on both sides of the intermediate layer as shown in FIG. 3B is obtained.
　この製造方法では、図３（ａ）に示された第一押圧ロール４４と第二押圧ロール４５との間の間隔を調整することによって、樹脂シート部１２の厚さが調整され得る。第二押圧ロール４５と第三押圧ロール４６の間の間隔を調整することによって、樹脂シート部１２の表面の表面粗さが調整され得る。 In this manufacturing method, the thickness of the resin sheet portion 12 can be adjusted by adjusting the distance between the first pressing roll 44 and the second pressing roll 45 shown in FIG. By adjusting the distance between the second pressing roll 45 and the third pressing roll 46, the surface roughness of the surface of the resin sheet portion 12 can be adjusted.
　得られた樹脂シート部１２の第２の表面部１２ｃに、スクリーン印刷又はインクジェット印刷によって拡散ドット（反射部２４）が形成される。その結果、光学シート１１が得られる。光学シート１１の作製方法は、これに限定されない。例えば、射出成型等によって、反射部２４が樹脂シート部１２の第２の表面部１２ｃに形成された光学シート１１が直接作製されてもよい。例えば、反射部２４が第２の表面部１２ｃに形成された凹凸形状である場合、上記樹脂シート部１２を製造する工程において、表面に所定のパターンを有する凹凸形状が設けられた押圧ロールを第二押圧ロール４５又は第三押圧ロール４６として用いることによって、光学シート１１が直接作製されてもよい。反射部２４として、拡散ドットの代わりに透明ドット又は半透明ドット等が用いられる場合、透明ドット又は半透明ドットは、拡散ドットの場合と同様にして形成され得る。以上の作製方法の一例では、温度等の製造条件を例示したが、光学シート１１の製造条件は例示した条件に限定されない。 A diffusion dot (reflecting part 24) is formed on the second surface part 12c of the obtained resin sheet part 12 by screen printing or ink jet printing. As a result, the optical sheet 11 is obtained. The manufacturing method of the optical sheet 11 is not limited to this. For example, the optical sheet 11 in which the reflecting portion 24 is formed on the second surface portion 12c of the resin sheet portion 12 may be directly manufactured by injection molding or the like. For example, when the reflecting portion 24 has a concavo-convex shape formed on the second surface portion 12c, in the step of manufacturing the resin sheet portion 12, a pressing roll having a concavo-convex shape having a predetermined pattern is provided on the surface. By using the second pressing roll 45 or the third pressing roll 46, the optical sheet 11 may be directly produced. When a transparent dot or a semi-transparent dot or the like is used as the reflecting portion 24 instead of the diffusion dot, the transparent dot or the semi-transparent dot can be formed in the same manner as the case of the diffusion dot. In the example of the manufacturing method described above, manufacturing conditions such as temperature are exemplified, but the manufacturing conditions of the optical sheet 11 are not limited to the exemplified conditions.
　本実施形態に係る樹脂シート部１２の作用効果が、図１に示されるように、面光源装置２２の一部として透過型画像表示装置１０に適用した場合を例にして説明される。光源部１４が有する光源１４Ａが発光すると、光源１４Ａからの光は、光源１４Ａに対向する樹脂シート部１２の側面１２ａから樹脂シート部１２に入射する。樹脂シート部１２に入射した光は、樹脂シート部１２内を全反射しながら伝播する。樹脂シート部１２内を伝播する光の一部は、反射部２４によって、光の全反射条件以外の条件で反射する。そのため、反射部２４で反射した光は、第１の表面部１２ｂ側から出射する。これにより第１の表面部１２ｂが面状の光を出射し得る。 The operation and effect of the resin sheet portion 12 according to the present embodiment will be described by taking as an example a case where it is applied to the transmissive image display device 10 as a part of the surface light source device 22, as shown in FIG. When the light source 14A of the light source unit 14 emits light, the light from the light source 14A enters the resin sheet unit 12 from the side surface 12a of the resin sheet unit 12 that faces the light source 14A. The light incident on the resin sheet portion 12 propagates while totally reflecting inside the resin sheet portion 12. A part of the light propagating through the resin sheet portion 12 is reflected by the reflecting portion 24 under conditions other than the light total reflection condition. Therefore, the light reflected by the reflecting portion 24 is emitted from the first surface portion 12b side. Thereby, the 1st surface part 12b can radiate | emit planar light.
　光学シート１１が有する樹脂シート部１２は、第１樹脂層１２ｄ及び第２樹脂層１２ｅが積層されてなる積層体である。第１樹脂層１２ｄ及び第２樹脂層１２ｅの主成分は、スチレン系樹脂である。そのため、光学シート１１は、低コストで製造され得る。樹脂シート部１２の一部を構成する第１樹脂層１２ｄは、第１樹脂層１２ｄの質量を基準として０．５質量％～３．０質量％の紫外線吸収剤及び０．１質量％～２．０質量％のヒンダードアミン系光安定剤を含む。そのため、樹脂シート部１２がスチレン系樹脂を主成分として構成されていても、紫外線照射に起因する樹脂の劣化が抑制され得る。第１樹脂層１２ｄは、紫外線吸収剤に加えてヒンダードアミン系光安定剤を含むため、紫外線吸収剤を添加することによる第１樹脂層１２ｄの黄色味を抑制し得る。その結果、光学シート１１を備える透過型画像表示装置１０は、自然により近い色合いで画像を表示し得る。 The resin sheet portion 12 included in the optical sheet 11 is a laminated body in which a first resin layer 12d and a second resin layer 12e are laminated. The main component of the first resin layer 12d and the second resin layer 12e is a styrene resin. Therefore, the optical sheet 11 can be manufactured at low cost. The first resin layer 12d constituting a part of the resin sheet portion 12 has an ultraviolet absorber of 0.5 mass% to 3.0 mass% and 0.1 mass% to 2 based on the mass of the first resin layer 12d. Contains 0% by weight of a hindered amine light stabilizer. Therefore, even if the resin sheet part 12 is comprised by making a styrene resin into a main component, deterioration of the resin resulting from ultraviolet irradiation can be suppressed. Since the 1st resin layer 12d contains a hindered amine light stabilizer in addition to an ultraviolet absorber, the yellowishness of the 1st resin layer 12d by adding an ultraviolet absorber can be controlled. As a result, the transmissive image display device 10 including the optical sheet 11 can display an image with a color closer to nature.
　樹脂シート部１２が、図２に示されるように、中間層としての第２樹脂層１２ｅの両側に、表層としての第１樹脂層１２ｄがそれぞれ設けられた構成である場合、光源部１４から樹脂シート部１２の側面１２ａに入射した光は、第２樹脂層１２ｅを主に伝搬する。その結果、光の透過率の低下がより抑制され得る。紫外線は、光学シート１１においてより表面積の大きい光学シート１１の第１の表面部１２ｂ側及び第２の表面部１２ｃ側から光学シート１１に入射しやすい。そのため、紫外線吸収剤及びヒンダードアミン系光安定剤を含む第１樹脂層１２ｄが、積層構造における最外層に配置されていることによって、紫外線照射による樹脂の劣化が効率的に抑制される。その結果、光学シート１１を備える透過型画像表示装置１０は、より自然に近い色合いで画像を表示し得る。第１樹脂層１２ｄのみに紫外線吸収剤及びヒンダードアミン系光安定剤を含むため、光学シート１１の製造時における紫外線吸収剤及びヒンダードアミン系光安定剤の使用量が抑制され得る。 As shown in FIG. 2, when the resin sheet portion 12 has a structure in which the first resin layer 12d as the surface layer is provided on both sides of the second resin layer 12e as the intermediate layer, the resin from the light source portion 14 The light incident on the side surface 12a of the sheet portion 12 mainly propagates through the second resin layer 12e. As a result, a reduction in light transmittance can be further suppressed. Ultraviolet rays are likely to enter the optical sheet 11 from the first surface portion 12 b side and the second surface portion 12 c side of the optical sheet 11 having a larger surface area in the optical sheet 11. Therefore, the first resin layer 12d containing the ultraviolet absorber and the hindered amine light stabilizer is disposed in the outermost layer in the laminated structure, so that deterioration of the resin due to ultraviolet irradiation is efficiently suppressed. As a result, the transmissive image display device 10 including the optical sheet 11 can display an image with a more natural hue. Since only the first resin layer 12d contains the ultraviolet absorber and the hindered amine light stabilizer, the amount of the ultraviolet absorber and the hindered amine light stabilizer used in manufacturing the optical sheet 11 can be suppressed.
　面光源装置２２は、樹脂シート部１２を有する光学シート１１を備える。したがって、面光源装置２２は、自然に近い色合いで、更に、輝度が確保された面状の光を出射し得る。透過型画像表示装置１０は、上記光学シート１１を備える。したがって、透過型画像表示装置１０は、自然に近い色合いで、更に、輝度が確保された画像を表示し得る。 The surface light source device 22 includes an optical sheet 11 having a resin sheet portion 12. Therefore, the surface light source device 22 can emit planar light having a brightness close to that of natural colors. The transmissive image display device 10 includes the optical sheet 11. Therefore, the transmissive image display apparatus 10 can display an image with a luminance that is close to natural and with a sufficient luminance.
　本発明は、以上説明した実施形態に限定されない。本発明は、本発明の趣旨を逸脱しない範囲で適宜変形が可能である。例えば、第１樹脂層１２ｄ及び第２樹脂層１２ｅの主成分であるスチレン系樹脂は、例示したポリスチレンに限定されず、スチレン系単量体単位を含む樹脂であればよい。例えば、第１樹脂層１２ｄ及び第２樹脂層１２ｅは、それぞれスチレン系単量体と（メタ）アクリル酸エステルとが共重合した樹脂であり得る。なお、本発明においては、（メタ）アクリル酸エステルは、メタクリル酸エステルとアクリル酸エステルとを含む意味である。 The present invention is not limited to the embodiment described above. The present invention can be modified as appropriate without departing from the spirit of the present invention. For example, the styrene resin that is the main component of the first resin layer 12d and the second resin layer 12e is not limited to the exemplified polystyrene, and may be a resin containing a styrene monomer unit. For example, the first resin layer 12d and the second resin layer 12e may be resins obtained by copolymerizing a styrene monomer and a (meth) acrylic acid ester, respectively. In the present invention, (meth) acrylic acid ester is meant to include methacrylic acid ester and acrylic acid ester.
　第１樹脂層１２ｄ又は第２樹脂層１２ｅの主成分が、スチレン系単量体と、（メタ）アクリル酸エステルとが共重合した樹脂である場合、スチレン系単量体単位の量は、（メタ）アクリル酸エステル単位の量以上であることが好ましい。すなわち、第１樹脂層１２ｄ及び第２樹脂層１２ｅを構成する樹脂は、スチレン系単量体単位の含有量が５０質量％～１００質量％であり、（メタ）アクリル酸エステル単位の含有量が０質量％～５０質量％である樹脂が好ましい。このようなスチレン系樹脂は、スチレン系単量体単位に由来するためか、紫外線照射による劣化が起きやすいので、本発明が好ましく適用される。このようなスチレン系単量体と、（メタ）アクリル酸エステル単量体とが共重合した樹脂の例は、スチレン単量体単位及びメタクリル酸メチル単量体単位を含む樹脂（ＭＳ樹脂）である。 When the main component of the first resin layer 12d or the second resin layer 12e is a resin obtained by copolymerizing a styrene monomer and a (meth) acrylic acid ester, the amount of the styrene monomer unit is ( It is preferable that it is more than the quantity of a meth) acrylic ester unit. That is, the resin constituting the first resin layer 12d and the second resin layer 12e has a styrene monomer unit content of 50% by mass to 100% by mass and a (meth) acrylic acid ester unit content. Resins that are 0% to 50% by weight are preferred. Since such a styrene-based resin is derived from a styrene-based monomer unit or is easily deteriorated by ultraviolet irradiation, the present invention is preferably applied. An example of a resin in which such a styrene monomer and a (meth) acrylic acid ester monomer are copolymerized is a resin (MS resin) containing a styrene monomer unit and a methyl methacrylate monomer unit. is there.
　スチレン系単量体としては、スチレンの他に、置換スチレン等が用いられ得る。置換スチレンは、例えば、クロロスチレン及びブロモスチレン等のハロゲン化スチレン、並びに、ビニルトルエン及びα－メチルスチレン等のアルキルスチレンが挙げられる。（メタ）アクリル酸エステルとしては、メタクリル酸メチルの他に、例えば、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸シクロヘキシル、メタクリル酸フェニル、メタクリル酸ベンジル、メタクリル酸２－エチルヘキシル及びメタクリル酸２－ヒドロキシエチル等のメタクリル酸エステル、並びに、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸シクロヘキシル、アクリル酸フェニル、アクリル酸ベンジル、アクリル酸２－エチルヘキシル及びアクリル酸２－ヒドロキシエチル等のアクリル酸エステルが挙げられる。 As the styrene monomer, substituted styrene or the like can be used in addition to styrene. Examples of the substituted styrene include halogenated styrene such as chlorostyrene and bromostyrene, and alkylstyrene such as vinyltoluene and α-methylstyrene. Examples of (meth) acrylic acid esters include, in addition to methyl methacrylate, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate and 2-hydroxyethyl methacrylate. And acrylate esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate Can be mentioned.
　樹脂シート部１２の層構造は、図４に示されるような、第１樹脂層１２ｄと第２樹脂層１２ｅとを１層ずつ有する２層構造でもよい。図４において、第１樹脂層１２ｄが樹脂シート部１２の第１の表面部１２ｂである。樹脂シート部１２の第１の表面部１２ｂは、図１において透過型画像表示部１８側にあり、樹脂の色合いが画像表示に影響を与えやすい領域である。このような第１の表面部１２ｂを、紫外線吸収剤及びヒンダードアミン系光安定剤を含む第１樹脂層１２ｄが形成することによって、紫外線照射による樹脂の劣化が抑制されて、より自然に近い色合いで画像を表示し得る。 The layer structure of the resin sheet portion 12 may be a two-layer structure having one first resin layer 12d and one second resin layer 12e as shown in FIG. In FIG. 4, the first resin layer 12 d is the first surface portion 12 b of the resin sheet portion 12. The first surface portion 12b of the resin sheet portion 12 is on the transmissive image display portion 18 side in FIG. 1, and is a region where the color of the resin tends to affect image display. By forming such a first surface portion 12b with the first resin layer 12d containing the ultraviolet absorber and the hindered amine light stabilizer, the deterioration of the resin due to the ultraviolet irradiation is suppressed, and the hue is more natural. An image can be displayed.
　第２樹脂層１２ｅは、紫外線吸収剤及びヒンダードアミン系光安定剤を含んでもよい。さらに、樹脂シート部１２は、多層構造に限らず単層であってもよい。例えば、第１樹脂層１２ｄと第２樹脂層１２ｅとが同一のスチレン系樹脂を含み、第１樹脂層１２ｄと第２樹脂層１２ｅとの界面において、紫外線吸収剤及びヒンダードアミン系光安定剤の濃度が段階的に変化してもよい。紫外線吸収剤とヒンダードアミン系光安定剤が、樹脂シート部１２中に均一に分散されていてもよい。紫外線照射による樹脂の劣化がより確実に抑制され得る。樹脂シート部１２を単層にすることで、製造工程が簡略化され、更に製造歩留まりが向上する。 The second resin layer 12e may contain an ultraviolet absorber and a hindered amine light stabilizer. Furthermore, the resin sheet portion 12 is not limited to a multilayer structure, and may be a single layer. For example, the first resin layer 12d and the second resin layer 12e contain the same styrene resin, and the concentration of the ultraviolet absorber and the hindered amine light stabilizer at the interface between the first resin layer 12d and the second resin layer 12e. May change step by step. The ultraviolet absorber and the hindered amine light stabilizer may be uniformly dispersed in the resin sheet portion 12. Deterioration of the resin due to ultraviolet irradiation can be more reliably suppressed. By making the resin sheet portion 12 a single layer, the manufacturing process is simplified, and the manufacturing yield is further improved.
　本実施形態に係る光学シート１１は、導光板としてだけではなく、光拡散板として用いられ得る。図５は、透過型画像表示装置の他の実施形態を示す端面図である。透過型画像表示装置１０は、透過型画像表示部１８と、透過型画像表示部１８の背面側（下側）に配置された直下型のバックライトユニットとしての面光源装置２２とを含んでいる。 The optical sheet 11 according to the present embodiment can be used not only as a light guide plate but also as a light diffusion plate. FIG. 5 is an end view showing another embodiment of the transmissive image display device. The transmissive image display device 10 includes a transmissive image display unit 18 and a surface light source device 22 as a direct type backlight unit disposed on the back side (lower side) of the transmissive image display unit 18. .
　面光源装置２２は、並列配置された複数の光源１４Ａを含む光源部１４を有する。各光源１４Ａは、複数の光源１４Ａの配列方向に直交する方向に延在している線状光源１４Ａである。光源１４Ａの例は、蛍光ランプ（冷陰極線ランプ）等の直管状の光源である。複数の光源１４Ａは、各光源１４Ａの中心軸線が同一の平面内に位置するように間隔をあけて配置されている。図５に示される透過型画像表示装置では、光源１４Ａは線状光源であるが、ＬＥＤ等の点光源等が用いられてもよい。 The surface light source device 22 has a light source unit 14 including a plurality of light sources 14A arranged in parallel. Each light source 14A is a linear light source 14A extending in a direction orthogonal to the arrangement direction of the plurality of light sources 14A. An example of the light source 14A is a straight tubular light source such as a fluorescent lamp (cold cathode ray lamp). The plurality of light sources 14A are arranged at intervals so that the central axes of the light sources 14A are located in the same plane. In the transmissive image display apparatus shown in FIG. 5, the light source 14A is a linear light source, but a point light source such as an LED may be used.
　面光源装置２２は、光源部１４の前面側（図５中、上側）、すなわち、透過型画像表示部１８側に、光源１４Ａに対して離間して配置された板状の光学シート（光拡散板）１１を有する。樹脂シート部１２の平面視形状は、例えば、長方形及び正方形等の四角形状が挙げられる。 The surface light source device 22 is a plate-like optical sheet (light diffusion) disposed on the front side of the light source unit 14 (upper side in FIG. 5), that is, on the transmissive image display unit 18 side and spaced from the light source 14A. Plate) 11. Examples of the planar view shape of the resin sheet portion 12 include rectangular shapes such as a rectangle and a square.
　さらに、本実施形態に係る光学シート１１は、拡散フィルム、プリズムフィルム及び輝度向上フィルム等の光学フィルム２０として用いられてもよい。 Furthermore, the optical sheet 11 according to the present embodiment may be used as an optical film 20 such as a diffusion film, a prism film, and a brightness enhancement film.
　以下、実施例を挙げて本発明がより詳細に説明されるが、本発明はこれらに限定されない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
　＜原材料＞
　本実施例及び比較例においては、樹脂シートを形成させるために以下の原材料及びマスターバッチペレットが用いられた。
熱可塑性樹脂Ａ：東洋スチレン（株）製、商品名、トーヨースチロールＨＲＭ－４０（スチレン系樹脂）
光拡散剤Ａ：ローム・アンド・ハースジャパン社製、商品名、パラロイドＥＸＬ５７６６
光拡散剤Ｂ：住友化学（株）製、商品名、スミペックスＸＣ１Ａ
紫外線吸収剤Ａ：城北化学工業（株）製、商品名、ＪＦ－７７
紫外線吸収剤Ｂ：（株）ＡＤＥＫＡ製、商品名、アデカスタブＬＡ－３１
ヒンダードアミン系光安定剤：ＢＡＳＦジャパン製、商品名、Ｔｉｎｕｖｉｎ７７０ＤＦ
熱安定剤：住友化学（株）製、商品名、スミライザーＧＰ
マスターバッチペレットＢ：８５．０質量部の熱可塑性樹脂Ａに対して、１４．０質量部の光拡散剤Ａと、１．０質量部の紫外線吸収剤Ａがドライブレンドされた。その後、ブレンドした物をスクリュー径３０ｍｍφの造粒機のホッパに投入し、１９０℃～２３０℃で溶融混練することによってマスターバッチペレットＢが作製された。 <Raw materials>
In the examples and comparative examples, the following raw materials and master batch pellets were used to form a resin sheet.
Thermoplastic resin A: manufactured by Toyo Styrene Co., Ltd., trade name, Toyostyrene HRM-40 (styrene resin)
Light diffusing agent A: manufactured by Rohm and Haas Japan, trade name, Paraloid EXL5766
Light diffusing agent B: manufactured by Sumitomo Chemical Co., Ltd., trade name, Sumipex XC1A
UV absorber A: Johoku Chemical Industry Co., Ltd., trade name, JF-77
Ultraviolet absorber B: Product name, ADK STAB LA-31, manufactured by ADEKA Corporation
Hindered amine light stabilizer: manufactured by BASF Japan, trade name, Tinuvin 770DF
Thermal stabilizer: Sumitomo Chemical Co., Ltd., trade name, Sumilizer GP
Master batch pellet B: 15.0 parts by mass of light diffusing agent A and 1.0 part by mass of ultraviolet absorber A were dry blended with respect to 85.0 parts by mass of thermoplastic resin A. Thereafter, the blended product was put into a hopper of a granulator having a screw diameter of 30 mmφ, and melted and kneaded at 190 ° C. to 230 ° C. to produce a master batch pellet B.
＜実施例１＞
　図３（ａ）に示した製造装置４０で樹脂シート部１２としての樹脂シートが製造された。９０．４質量部の熱可塑性樹脂Ａに対して、８．０質量部の光拡散剤Ｂと、１．０質量部の紫外線吸収剤Ｂと、０．５質量部のヒンダードアミン系光安定剤と、０．１０質量部の熱安定剤とがドライブレンドされた。その後、ブレンドした物をスクリュー径３０ｍｍφの造粒機のホッパに投入し、１９０℃～２３０℃で溶融混練することによってマスターバッチペレットＣが作製された。 <Example 1>
The resin sheet as the resin sheet part 12 was manufactured with the manufacturing apparatus 40 shown to Fig.3 (a). With respect to 90.4 parts by mass of thermoplastic resin A, 8.0 parts by mass of light diffusing agent B, 1.0 part by mass of ultraviolet absorber B, 0.5 parts by mass of hindered amine light stabilizer, And 0.10 parts by mass of a heat stabilizer were dry blended. Thereafter, the blended product was put into a hopper of a granulator having a screw diameter of 30 mmφ, and melt-kneaded at 190 ° C. to 230 ° C. to produce master batch pellets C.
　１００質量部のマスターバッチペレットＣが第２押出機４２（スクリュー径２０ｍｍφの単軸押出機）にて２００℃～２４５℃で溶融混練された。１１質量部のマスターバッチペレットＢと８９質量部の熱可塑性樹脂Ａがブレンド（ハンドブレンド）された。その後、ブレンドした物が第１押出機４１（スクリュー径４０ｍｍφの単軸押出機）にて２００℃～２４５℃で溶融混練された。そして、溶融混練されたそれぞれの樹脂が幅２５０ｍｍのマルチマニホールドダイ４３から、ダイ温度２４５℃で２種３層の構造の樹脂シートとして連続的に共押出された。この押出された樹脂シートが、鏡面冷却ロールである第一押圧ロール４４と第二押圧ロール４５とで押圧された。その後、この樹脂シートが第二押圧ロール４５に密着された状態で第二押圧ロール４５の回転に伴って搬送された。次いで樹脂シートが、第二押圧ロール４５と第三押圧ロール４６とで押圧された。これにより、紫外線吸収剤及びヒンダードアミン系光安定剤を含む表層（第１樹脂層１２ｄ）が樹脂シートの両面にある実施例１の樹脂シート部１２としての樹脂シートが製造された。得られた樹脂シートの表層の厚みは、５０μｍであった。得られた樹脂シートの板厚みは、２．０ｍｍであった。 100 parts by mass of the master batch pellet C was melt-kneaded at 200 ° C. to 245 ° C. in the second extruder 42 (single screw extruder having a screw diameter of 20 mmφ). 11 parts by mass of master batch pellet B and 89 parts by mass of thermoplastic resin A were blended (hand blended). Thereafter, the blended product was melt-kneaded at 200 ° C. to 245 ° C. in a first extruder 41 (single screw extruder having a screw diameter of 40 mmφ). Each melt-kneaded resin was continuously coextruded from a multi-manifold die 43 having a width of 250 mm as a resin sheet having a two-kind / three-layer structure at a die temperature of 245 ° C. The extruded resin sheet was pressed by the first pressing roll 44 and the second pressing roll 45 which are mirror surface cooling rolls. Thereafter, the resin sheet was conveyed along with the rotation of the second pressing roll 45 in a state of being in close contact with the second pressing roll 45. Next, the resin sheet was pressed by the second pressing roll 45 and the third pressing roll 46. Thereby, the resin sheet as the resin sheet part 12 of Example 1 which has the surface layer (1st resin layer 12d) containing a ultraviolet absorber and a hindered amine light stabilizer on both surfaces of the resin sheet was manufactured. The thickness of the surface layer of the obtained resin sheet was 50 μm. The plate thickness of the obtained resin sheet was 2.0 mm.
＜実施例２＞
　８９．９質量部の熱可塑性樹脂Ａに対して、８．０質量部の光拡散剤Ｂと、１．０質量部の紫外線吸収剤Ｂと、１．０質量部のヒンダードアミン系光安定剤と、０．１０質量部の熱安定剤がドライブレンドされた。ブレンドした物をスクリュー径３０ｍｍφの造粒機のホッパに投入し、１９０℃～２３０℃で溶融混練することによって、マスターバッチペレットＤが作製された。 <Example 2>
To 89.9 parts by mass of thermoplastic resin A, 8.0 parts by mass of light diffusing agent B, 1.0 part by mass of ultraviolet absorber B, 1.0 part by mass of a hindered amine light stabilizer, 0.10 parts by weight of heat stabilizer was dry blended. The blended product was put into a hopper of a granulator having a screw diameter of 30 mmφ, and melt-kneaded at 190 ° C. to 230 ° C. to produce a master batch pellet D.
　マスターバッチペレットＣの代わりにマスターバッチペレットＤを用いたこと以外は実施例１と同様の方法で、樹脂シート部１２としての樹脂シートが製造された。 A resin sheet as the resin sheet portion 12 was produced in the same manner as in Example 1 except that the master batch pellet D was used instead of the master batch pellet C.
＜比較例１＞
　９０．９質量部の熱可塑性樹脂Ａに対して、８．０質量部の光拡散剤Ｂと、１．０質量部の紫外線吸収剤Ｂと、０．１０質量部の熱安定剤がドライブレンドされた。ブレンドした物をスクリュー径３０ｍｍφの造粒機のホッパに投入し、１９０℃～２３０℃で溶融混練することによって、マスターバッチペレットＥが作製された。 <Comparative Example 1>
For 90.9 parts by mass of thermoplastic resin A, 8.0 parts by mass of light diffusing agent B, 1.0 part by mass of ultraviolet absorber B, and 0.10 parts by mass of thermal stabilizer are dry blended. It was done. The blended product was put into a hopper of a granulator having a screw diameter of 30 mmφ, and melt-kneaded at 190 ° C. to 230 ° C., thereby producing a master batch pellet E.
　マスターバッチペレットＣの代わりにマスターバッチペレットＥを用いたこと以外は実施例１と同様の方法で、樹脂シートが製造された。 A resin sheet was produced in the same manner as in Example 1 except that master batch pellet E was used instead of master batch pellet C.
＜比較例２＞
　８９．４質量部の熱可塑性樹脂Ａに対して、８．０質量部の光拡散剤Ｂと、２．５質量部の紫外線吸収剤Ｂと、０．１０質量部の熱安定剤がドライブレンドされた。ブレンドした物をスクリュー径３０ｍｍφの造粒機のホッパに投入し、１９０℃～２３０℃で溶融混練することによって、マスターバッチペレットＦが作製された。 <Comparative example 2>
For 89.4 parts by mass of thermoplastic resin A, 8.0 parts by mass of light diffusing agent B, 2.5 parts by mass of ultraviolet absorber B, and 0.10 parts by mass of thermal stabilizer are dry blended. It was done. The blended product was put into a hopper of a granulator having a screw diameter of 30 mmφ, and melt-kneaded at 190 ° C. to 230 ° C. to produce a master batch pellet F.
　マスターバッチペレットＣの代わりにマスターバッチペレットＦを用いたこと以外は実施例１と同様の方法で、樹脂シートが製造された。 A resin sheet was produced in the same manner as in Example 1 except that the master batch pellet F was used instead of the master batch pellet C.
＜耐久性評価用のサンプル作製方法＞
　得られた各樹脂シートを６５ｍｍ角にパネルソーにて切出すことによって、長さ６５ｍｍ×幅６５ｍｍ×厚み２．０ｍｍの耐久性評価用のサンプルが得られた。 <Sample preparation method for durability evaluation>
Each obtained resin sheet was cut into a 65 mm square with a panel saw to obtain a sample for durability evaluation of length 65 mm × width 65 mm × thickness 2.0 mm.
＜耐久性の評価方法＞
　耐久性評価用のサンプルが、水銀灯照射装置（ＥＳＰＥＣ　ＣＯＲＰ．製、商品名ＰＨ－２０１）の水銀灯ランプ（岩崎電気、４００Ｗ）から２０ｃｍ離れた位置に取り付けられた。耐久性評価用のサンプルを取り付けた位置の照度は１ｍＷ／ｃｍ２とした。耐久性評価用のサンプルは所定の時間ごとに取り出され、耐久性評価用のサンプルの黄色度（ＹＩ）が測定された。耐久性評価用のサンプルとして同一のサンプルが使用された。耐久性評価用のサンプルの黄色度が分光光度計（日立ハイテクノロジー社製、商品名、Ｕ－４１００）にて、０、５００、１０００、１５００及び２０００時間ごとに測定された。 <Durability evaluation method>
A sample for durability evaluation was attached at a position 20 cm away from a mercury lamp lamp (Iwasaki Electric, 400 W) of a mercury lamp irradiation apparatus (trade name PH-201, manufactured by ESPEC CORP.). The illuminance at the position where the sample for durability evaluation was attached was 1 mW / cm 2 . A sample for durability evaluation was taken out every predetermined time, and the yellowness (YI) of the sample for durability evaluation was measured. The same sample was used as a sample for durability evaluation. The yellowness of a sample for durability evaluation was measured every 0, 500, 1000, 1500 and 2000 hours with a spectrophotometer (trade name, U-4100, manufactured by Hitachi High-Technology Corporation).
　次に、上記のようにして得られた各樹脂シートにおける黄色度（ＹＩ）及び初期値からの黄色度の変化量（ΔＹＩ）が評価された。その評価結果が表１に示される。なお、表１中、かっこ内の数値はΔＹＩを示している。 Next, the yellowness (YI) and the amount of change in yellowness (ΔYI) from the initial value in each resin sheet obtained as described above were evaluated. The evaluation results are shown in Table 1. In Table 1, the numerical value in parentheses indicates ΔYI.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　比較例２のサンプル（紫外線吸収剤２．５質量％）では、比較例１のサンプル（紫外線吸収剤１質量％）に比べて、ΔＹＩが低く紫外線照射による樹脂の劣化が抑えられていた。しかし、初期値のＹＩを比較すると、比較例２のサンプルの方が比較例１のサンプルよりも大きい値を有しており、樹脂が黄色味を帯びていることが示唆された。すなわち、紫外線吸収剤をより多く樹脂に添加することで、紫外線が照射されることによる樹脂の黄色味が抑えられるが、紫外線吸収剤の添加自体で、樹脂の黄色味が増加する傾向がある。一方、実施例１のサンプル（紫外線吸収剤１質量％、ヒンダードアミン系光安定剤０．５質量％）及び実施例２のサンプル（紫外線吸収剤１質量％、ヒンダードアミン系光安定剤１質量％）では、紫外線照射から２０００時間後のΔＹＩが、比較例１及び２のサンプルに比べて、１／６～１／４の値であり、紫外線照射による樹脂の劣化が大きく抑えられていた。さらに、ヒンダードアミン系光安定剤を含むことで、ＹＩの初期値が、比較例２のサンプルに比べて小さく、紫外線吸収剤の添加自体による樹脂の黄色味が抑えられていることが分かった。以上のことから、本発明に係る光学シートは、黄色味が抑制されるとともに紫外線照射による樹脂の劣化を抑制した光学シートであることが明らかとなった。 In the sample of Comparative Example 2 (UV absorber 2.5% by mass), ΔYI was lower than that of the sample of Comparative Example 1 (UV absorber 1% by mass), and deterioration of the resin due to UV irradiation was suppressed. However, comparing the initial values of YI, the sample of Comparative Example 2 has a larger value than the sample of Comparative Example 1, suggesting that the resin is yellowish. That is, by adding more ultraviolet absorber to the resin, the yellowness of the resin due to the irradiation with ultraviolet rays can be suppressed, but the addition of the ultraviolet absorber itself tends to increase the yellowness of the resin. On the other hand, in the sample of Example 1 (ultraviolet absorber 1 mass%, hindered amine light stabilizer 0.5 mass%) and the sample of Example 2 (ultraviolet absorber 1 mass%, hindered amine light stabilizer 1 mass%). ΔYI after 2000 hours from the ultraviolet irradiation was a value of 1/6 to 1/4 compared with the samples of Comparative Examples 1 and 2, and the deterioration of the resin due to the ultraviolet irradiation was greatly suppressed. Furthermore, it was found that by including a hindered amine light stabilizer, the initial value of YI was smaller than that of the sample of Comparative Example 2, and the yellowness of the resin due to the addition of the ultraviolet absorber itself was suppressed. From the above, it has been clarified that the optical sheet according to the present invention is an optical sheet in which yellowness is suppressed and deterioration of the resin due to ultraviolet irradiation is suppressed.
１０…透過型画像表示装置、１１…光学シート、１２…樹脂シート部、１２ａ…側面、１２ｂ…第１の表面部（出射部）、１２ｃ…第２の表面部（背面部）、１２ｄ…第１樹脂層、１２ｅ…第２樹脂層、１４…光源部、１６…反射部材、１８…透過型画像表示部、２０…光学フィルム部、２２…面光源装置、２４…反射部（拡散ドット）。 DESCRIPTION OF SYMBOLS 10 ... Transmission type image display apparatus, 11 ... Optical sheet, 12 ... Resin sheet part, 12a ... Side surface, 12b ... 1st surface part (output part), 12c ... 2nd surface part (back part), 12d ... 1st DESCRIPTION OF SYMBOLS 1 resin layer, 12e ... 2nd resin layer, 14 ... Light source part, 16 ... Reflective member, 18 ... Transmission-type image display part, 20 ... Optical film part, 22 ... Surface light source device, 24 ... Reflection part (diffusion dot).

Claims (9)

  1. 　スチレン系樹脂を含む樹脂シート部を備え、
    　第１の表面部、及び前記樹脂シート部の厚さ方向における前記第１の表面部と反対側の第２の表面部のうち少なくとも一方が、紫外線吸収剤とヒンダードアミン系光安定剤とを含む、光学シート。     A resin sheet containing a styrene resin is provided,
    At least one of the first surface portion and the second surface portion opposite to the first surface portion in the thickness direction of the resin sheet portion includes an ultraviolet absorber and a hindered amine light stabilizer, Optical sheet.
  2. 　前記樹脂シート部が前記スチレン系樹脂を含み、前記第１及び第２の表面部のうち少なくとも一方を形成する第１樹脂層と、前記スチレン系樹脂を含む第２樹脂層とを備え、
    　前記第１樹脂層は前記第２樹脂層に積層されており、前記第１樹脂層は前記紫外線吸収剤と前記ヒンダードアミン系光安定剤とを含み、
    　前記第２樹脂層は前記紫外線吸収剤と前記ヒンダードアミン系光安定剤とを含まない、請求項１に記載の光学シート。     The resin sheet portion includes the styrene resin, and includes a first resin layer that forms at least one of the first and second surface portions, and a second resin layer that includes the styrene resin.
    The first resin layer is laminated on the second resin layer, and the first resin layer includes the ultraviolet absorber and the hindered amine light stabilizer,
    The optical sheet according to claim 1, wherein the second resin layer does not include the ultraviolet absorber and the hindered amine light stabilizer.
  3. 　前記樹脂シート部が、２つの前記第１樹脂層を有し、前記樹脂シート部の厚さ方向において２つの前記第１樹脂層の間に前記第２樹脂層が挟まれており、２つの前記第１樹脂層の一方が前記第１の表面部を形成し、他方が前記第２の表面部を形成する、請求項２に記載の光学シート。 The resin sheet portion has two first resin layers, and the second resin layer is sandwiched between two first resin layers in the thickness direction of the resin sheet portion, and the two The optical sheet according to claim 2, wherein one of the first resin layers forms the first surface portion, and the other forms the second surface portion.
  4. 　前記紫外線吸収剤と前記ヒンダードアミン系光安定剤は、前記樹脂シート部中に均一に分散されている、請求項１に記載の光学シート。 2. The optical sheet according to claim 1, wherein the ultraviolet absorber and the hindered amine light stabilizer are uniformly dispersed in the resin sheet portion.
  5. 　前記スチレン系樹脂が、ポリスチレン樹脂又はスチレン単量体単位及びメタクリル酸メチル単量体単位を含む樹脂である、請求項１～４のいずれか一項に記載の光学シート。 The optical sheet according to any one of claims 1 to 4, wherein the styrene-based resin is a polystyrene resin or a resin containing a styrene monomer unit and a methyl methacrylate monomer unit.
  6. 　請求項１～５のいずれか一項に記載の光学シートであって、前記光学シートの前記樹脂シート部の前記第２の表面部側に設けられており前記第１の表面部側に光を反射する反射部を有する光学シートと、
    　前記第１の表面部及び前記第２の表面部と交差しており、前記光学シートが有する前記樹脂シート部の側面に光を供給する光源部と、
    　を備える面光源装置。     The optical sheet according to any one of claims 1 to 5, wherein the optical sheet is provided on the second surface portion side of the resin sheet portion of the optical sheet and emits light to the first surface portion side. An optical sheet having a reflecting portion to reflect;
    A light source section that intersects the first surface section and the second surface section and supplies light to the side surface of the resin sheet section of the optical sheet;
    A surface light source device comprising:
  7. 　請求項１～５のいずれか一項に記載の光学シートであって、前記光学シートが有する前記樹脂シート部の前記第２の表面部から入射された光を前記第１の表面部から拡散して出射する前記光学シートと、
    　前記光学シートが有する前記樹脂シート部の前記第２の表面部に光を供給する光源部と、
    　を備える面光源装置。     The optical sheet according to any one of claims 1 to 5, wherein light incident from the second surface portion of the resin sheet portion of the optical sheet is diffused from the first surface portion. The optical sheet exiting
    A light source part for supplying light to the second surface part of the resin sheet part of the optical sheet;
    A surface light source device comprising:
  8. 　請求項１～５のいずれか一項に記載の光学シートであって、前記光学シートの前記樹脂シート部の前記第２の表面部側に設けられており前記第１の表面部側に光を反射する反射部を有する光学シートと、
    　前記第１の表面部及び前記第２の表面部と交差しており、前記光学シートが有する前記樹脂シート部の側面に光を供給する光源部と、
    　前記第１の表面部側に設けられ、前記第１の表面部から出射される面状の光で照明される透過型画像表示部と、
    を備える透過型画像表示装置。     The optical sheet according to any one of claims 1 to 5, wherein the optical sheet is provided on the second surface portion side of the resin sheet portion of the optical sheet and emits light to the first surface portion side. An optical sheet having a reflecting portion to reflect;
    A light source section that intersects the first surface section and the second surface section and supplies light to the side surface of the resin sheet section of the optical sheet;
    A transmissive image display unit that is provided on the first surface portion side and is illuminated with planar light emitted from the first surface portion;
    A transmissive image display device.
  9. 　請求項１～５のいずれか一項に記載の光学シートであって、前記光学シートが有する前記樹脂シート部の前記第２の表面部から入射された光を前記第１の表面部から拡散して出射する前記光学シートと、
    　前記光学シートが有する前記樹脂シート部の前記第２の表面部に光を供給する光源部と、
    　前記第１の表面部側に設けられ、前記第１の表面部から出射される面状の光で照明される透過型画像表示部と、
    を備える透過型画像表示装置。     The optical sheet according to any one of claims 1 to 5, wherein light incident from the second surface portion of the resin sheet portion of the optical sheet is diffused from the first surface portion. The optical sheet exiting
    A light source part for supplying light to the second surface part of the resin sheet part of the optical sheet;
    A transmissive image display unit that is provided on the first surface portion side and is illuminated with planar light emitted from the first surface portion;
    A transmissive image display device.
PCT/JP2012/065639 2011-07-14 2012-06-19 Optical sheet, planar light source device, and transmission image display device WO2013008589A1 (en)

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CN103688102A (en) 2014-03-26

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