JP2003303508A - Surface light source device and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent display device capable of protecting components from ultraviolet radiation from a light source of a surface light source device and stabilizing display quality for a long period. <P>SOLUTION: The transparent display device 1 comprises a liquid crystal display unit 2 and a surface light source unit 3. The surface light source unit includes a tubular light source 4, light guiding member 5, a light diffusion film 7 with ultraviolet absorption capability, and a prism sheet 8. The light diffusion film 7 absorbs ultraviolet radiation from a light source (fluorescent tube) of a surface light source device (back light) to protect the diffusion sheet 7, the prism sheet 8 and liquid crystal display cells from being deteriorated. The light diffusion film may be constituted by a light diffusion layer constituted by a plurality of resins each having a different angle of refraction and a transparent resin film laminated on the light diffusion layer, wherein at least the transparent resin film includes a ultraviolet absorption material. The light diffusion film may be an anisotropy diffusion film which diffuses anisotropically. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device and a transmissive liquid crystal display device using a light diffusion film useful for diffusing light rays.

[0002]

2. Description of the Related Art Display panels (such as liquid crystal display modules)
In a backlight type display device (a liquid crystal display device or the like) that illuminates the back surface of the display panel, a surface light source unit (or a backlight unit) is provided on the back surface of the display panel.
Further, a diffusion sheet, a prism sheet, a brightness enhancement sheet (a reflection type deflection plate, etc.) and the like are used in order to make the irradiation light to the display panel uniform as a surface light source and to increase the brightness in front of the liquid crystal display device. Further, in the liquid crystal display device, a deflection plate, a retardation plate or the like is used as a constituent member of the liquid crystal cell. Furthermore, liquid crystal substances and color filters are also used.

More specifically, for example, as a planar display device (planar display device) whose image display area is flat (planar), as shown in FIG. 6, a planar display unit (transmissive liquid crystal display unit) is used. Etc.) and a surface light source unit for illuminating this unit from the back side are known. This surface light source unit has one or a plurality of fluorescent discharge tubes (cold cathode tubes) 41, and a reflecting plate 42 for reflecting light is disposed on the back side of the fluorescent discharge tubes 41, and A diffusion plate 43 for diffusing light and illuminating the display unit 45 uniformly is disposed between the discharge tube 41 and the display unit 45, and a prism sheet 44 is laminated on the display unit side of the diffusion plate 43. Has been done. In the case of a liquid crystal display unit, the planar display unit 45 includes a first polarizing film 46a, a first glass substrate 47a, a first electrode 48a formed on the glass substrate, and a first electrode laminated on the electrode. Alignment film 49a, liquid crystal layer 50, second alignment film 49b, second electrode 48b, color filter 5
It is formed by sequentially laminating the first and second glass substrates 47b and the second polarizing film 46b. In such a display device, the display unit can be directly illuminated from the back surface by the fluorescent tube (cold cathode tube) 41.

Further, in the surface type display device shown in FIG.
There is known an apparatus using a backlight unit having a light guide plate as shown in FIG. 7 in the backlight section.
The backlight unit includes a tubular light source 51 such as a fluorescent tube (cold-cathode tube) and a light guide plate 54 disposed with its side surface adjacent to the tubular light source and guiding light from the tubular light source to a display panel. The light guide plate 54 is composed of a diffusion plate 53 provided on the upper side (light emitting surface or front surface) and a reflection plate 55 provided on the opposite side of the light guide plate to the display unit. The thickness of the light guide plate 54 is larger on the tubular light source 51 side, and the light from the tubular light source 51 is
While being guided by the light guide plate 54, it is reflected by the reflection plate 55 and emitted from the light exit surface (front surface) of the light guide plate 54, and then the diffusion plate 53.
After being diffused by, the light is incident on a surface type display unit (not shown) laminated on the diffusion plate. In order to improve the brightness of the display device, when a plurality of tubular light sources are arranged on the light guide plate (when fluorescent tubes are used on both sides or two or more sides of the light guide plate), generally the entire surface is substantially Light guide plates of the same thickness can be used.

Under the light guide plate, white scatterers for widely and radially scattering the light are regularly arranged in dots to form light scattering dots.

However, in the surface light source device using the fluorescent discharge tube, the light guide plate, the diffusion plate, the prism sheet (if necessary, a protective film for the prism sheet) as described above, the number of parts is large, and therefore the raw material cost is high. However, the assembly cost is high, and foreign matter is likely to be mixed between each component, resulting in a high defect rate. It should be noted that it is possible to remove the foreign matter, but the assembling cost becomes higher. Therefore, a low cost surface light source device is desired.

In recent years, as a surface light source device having a low cost and a simple structure, a surface light source device has been proposed in which a wedge-shaped reflection groove is formed in the lower portion of a light guide plate and the reflected light is used (Japanese Patent Laid-Open No. 2000-2000). -305073, JP 2000-
34185, JP-A-2000-352719, JP-A-2000-353413, etc.).

However, in the conventional liquid crystal display device, ultraviolet rays leak from a tubular light source such as a fluorescent tube, and the constituent members of the surface light source unit (for example, the above-mentioned diffusion sheet, prism sheet, and brightness enhancement sheet (such as a reflection type deflection plate). ), A polarizing plate, a retardation plate, a liquid crystal substance or a color filter) deteriorates after long-term use.

In Japanese Patent Application Laid-Open No. 11-246704, a polarizing plate protective film containing an ultraviolet protective agent is used.
It has been proposed to protect liquid crystal cells.

In order to prevent the leakage of ultraviolet rays,
In the backlight unit, a method of arranging an ultraviolet absorbing film in the vicinity of the fluorescent tube or adding an ultraviolet absorber to the light guide plate to prevent leakage of ultraviolet rays can be considered. However, in the former method, it is necessary to use a film having high heat resistance, and in the latter method, the ultraviolet absorber slightly absorbs visible light, so that the hue changes throughout.

In order to prevent the leakage of ultraviolet rays, a fluorescent substance (magnesium oxide, titanium oxide, etc.) is used as a white scatterer formed under the light guide plate, and a small amount of ultraviolet rays is converted into visible light from the fluorescent tube. Is proposed. However, even with such a method, ultraviolet rays leak from the backlight unit. Therefore, the diffusion sheet, the prism sheet, and the brightness enhancement sheet (such as the reflection type deflection plate) are exposed to ultraviolet rays for a long period of time and become yellowish. Especially in the backlight where the wedge-shaped reflection groove is formed in the lower part of the light guide plate,
Since the white scatterer composed of the above phosphor is not used,
Strong ultraviolet rays leak from the light guide plate.

JP-A-2001-31774 discloses that a sea-island structure light-scattering sheet made of resins having different refractive indices has an average particle size of the island polymer of 0.5 to 10.
μm, the ratio of sea polymer and island polymer is 70/30 ~
40/60 (weight ratio) and sheet thickness is 5 to 200
A transmission type light-scattering sheet having a thickness of μm is disclosed. This document also discloses that scattered light is directed and diffused within a scattering angle range of 5 to 50 °.

[0013]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a transmissive display device (particularly, a transmissive liquid crystal display device) which can stably maintain the display quality for a long period of time and is constructed from ultraviolet rays leaking from a light source. An object of the present invention is to provide a device (a surface light source device and a display device) provided with a light scattering film that can effectively protect components.

Another object of the present invention is to provide a backlight using a wedge-shaped reflecting groove formed in the lower part of a light guide plate without using a white scatterer composed of a fluorescent material, and to prevent components from leaking ultraviolet rays. An object of the present invention is to provide a device (a surface light source device and a display device) using a light scattering film that can effectively protect the light.

[0015]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors found that a film having light diffusing property and ultraviolet absorbing property is provided on the light emitting surface of a surface light source unit. It is possible to prevent ultraviolet rays from leaking at a low cost reliably and with high reliability for a long period of time, and to effectively protect various components used for the surface light source device and the liquid crystal cell from the leaking ultraviolet rays, and The present invention has been completed by finding that the deterioration of the function can be prevented.

That is, the surface light source device of the present invention is provided with a light guide plate whose side portion is arranged close to the light source, and which guides light from the light source, and a light guide plate formed below the light guide plate.
A surface light source unit including a wedge-shaped reflection groove for reflecting the light guided by the light guide plate to the light exit surface side, and an ultraviolet absorbing light diffusing film disposed on the light exit surface side of the light guide plate. Is equipped with. When a light guide plate having a wedge-shaped reflection groove is used, almost regular reflection light of the light incident on the slope of the wedge can be used for illumination, so a white scatterer is not required,
The ultraviolet absorbing light diffusing film can be effectively used. The ultraviolet absorptive light diffusing film comprises a light diffusing layer (1) made of a plurality of resins having different refractive indexes, and a transparent resin layer (2) laminated on at least one surface of the light diffusing layer.
The ultraviolet absorber can be contained in the light diffusion layer and / or the transparent resin layer, and is usually contained in at least the transparent resin layer (2). By arranging the transparent resin layer (2) of such a laminated film on the light emitting surface of the surface light source unit, (1) the light diffusing layer can be effectively protected and UV leakage can be prevented more stably.

The ultraviolet absorbing light diffusing film may have light scattering anisotropy (or anisotropic light scattering). By using such a film, it is possible to realize the uniformity of the brightness of the display surface as a surface light source device even when viewed from a wide angle in the left-right and up-down directions. For example, in the scattering characteristic F (θ) showing the relationship between the scattering angle θ and the scattered light intensity F, the scattering characteristic in the X-axis direction of the film is Fx (θ) and the scattering characteristic in the Y-axis direction is Fy (θ). At this time, the scattered light intensity characteristic of the anisotropic light-scattering film is F at the scattering angle θ = 4 to 30 °.
y (θ) / Fx (θ)> 1.01 (preferably ≧ 1.
Satisfy 1). With such an anisotropic light-scattering film, it is possible to clearly realize the uniformity of brightness in the left-right direction or the vertical direction.

A transmissive liquid crystal display device of the present invention includes the surface light source device. In this device, the light diffusion film having anisotropic light diffusion property may be arranged in various directions with respect to the surface light source unit. For example, the left-right direction (lateral direction) of the liquid crystal display surface is defined as the Y axis. At this time, the Y axis (main light scattering direction) of the ultraviolet absorbing light diffusing film may be arranged along the Y axis of the liquid crystal display surface. If the light diffusing film is arranged in such a direction, the standard (TCO, The Swedish Co
nfederation of Professional employee) can be satisfied.

In the present specification, the term "film" is used to mean a sheet regardless of its thickness.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Below, referring to the attached drawings,
The present invention will be described in detail. FIG. 1 is a schematic exploded perspective view showing an example of a surface light source device and a transmission type liquid crystal display device of the present invention.

In FIG. 1, the display device 1 includes a liquid crystal display unit (or liquid crystal display panel) 2 as an irradiation target, which includes a liquid crystal cell in which liquid crystal is sealed, and a rear side of the display unit (or panel). And a surface light source unit 3 for illuminating the display unit 2.

The surface light source unit 3 is composed of a tubular light source 4 such as a fluorescent tube (cold-cathode tube) and a translucent plate-like member, and a light guide member (where the tubular light sources are arranged adjacent to each other). A light guide plate 5 and the tubular light source 4 are disposed laterally,
A reflection mirror 6b for reflecting the light from the light source to the side surface of the light guide member 5 and the light from the tubular light source 4 arranged on the back surface side of the light guide member 5 in the forward direction (display unit side). A reflection member or a reflection layer 6a for reflecting the light and guiding it to the display unit 2. The light from the tubular light source 4 enters from the side surface of the light guide member 5 and exits from the flat exit surface to illuminate the display unit. At that time, the ultraviolet light generated from the tubular light source 4 passes through the light guide member (light guide plate) 5, is emitted from the emission surface, and leaks. Further, generally, the brightness distribution of the light emitted from the tubular light source 4 is not uniform, and the brightness distribution in the direction orthogonal to the axial direction of the tubular light source 4 is not uniform. Therefore, even if light is emitted from the emission surface through the light guide member 5, the display unit 2 cannot be illuminated uniformly.

Therefore, in the present invention, a film 7 having both ultraviolet absorbing property and light diffusing property on the emitting surface side of the light guide member 5 (light emitting surface side of the surface light source unit) and a micro prism having a triangular cross section. And prism sheets 8 formed in parallel in a predetermined direction are sequentially laminated and arranged. for that reason,
The light from the tubular light source 4 is diffused through the light guide member 5 by the ultraviolet absorbing light diffusing film 7 to be uniformized and becomes visible light substantially containing no ultraviolet light, and is collected forward by the prism sheet 8. The display unit 2 can be illuminated from the backside by illuminating and increasing the brightness. Then, it is possible to prevent yellowing of the light guide plate, the diffusion sheet, the prism sheet (the brightness improving sheet if necessary), and to suppress the hue change on the display surface of the liquid crystal display device. In addition, it is possible to suppress deterioration of the polarizing plate and its protective film (such as a cellulose triacetate layer) generally attached to the surface of the liquid crystal display panel.
Therefore, the display quality can be stabilized for a long period of time. Furthermore, since a single film can impart high light-scattering property and ultraviolet blocking property, the structure of the surface light source device and the liquid crystal display device can be simplified without the need for a white scatterer composed of an ultraviolet absorbing film or a phosphor. Can be converted.

In the present invention, at least the ultraviolet absorbing light diffusing film may be disposed on the emission surface side of the surface light source unit, and it is not necessary to use it in combination with the prism sheet or the brightness improving sheet. The light scattering sheet may be interposed between the surface light source unit and the display unit, and need not be laminated on the emission surface of the surface light source unit.

The light diffusing film may have a light diffusing property and an ultraviolet absorbing property, and may have a single layer structure or a laminated structure. Further, on the back surface of the light guide member (light guide plate), various reflecting means may be formed, for example, reflecting means constituted by a wedge-shaped groove not limited to the reflecting layer.

FIG. 2 is a schematic view for explaining another example of the surface light source unit provided with the light diffusion film. In this example, a light guide member (light guide plate) 15, a tubular light source 4 arranged adjacent to a side portion of the light guide plate, and a laminated or arranged light emitting surface of the light guide plate 15 and absorbing ultraviolet light. A single-layer structure light-scattering film 17 containing an agent, and a wedge-shaped reflection groove (or reflection uneven portion) 18 formed on the back surface of the light guide plate 15 for reflecting light from the light source in the emission surface direction. I have it. Further, the light diffusion film 17 having a single-layer structure is composed of a plurality of resins having different refractive indexes, and the continuous layer 1
7a has a phase separation structure (or sea-island structure) in which dispersed phase particles 17b are dispersed.

When the surface light source unit is composed of the light guide plate 15 having the wedge-shaped reflection groove 18 and the light diffusion film 17 as described above, the side surface of the light guide plate 15 is arranged close to the tubular light source. While guiding the light from the light source by the wedge-shaped reflection groove 18 formed in the lower portion of the light guide plate 15,
The light guided by the light guide plate can be reflected toward the light emitting surface side and emitted. Therefore, it is not necessary to form a white scatterer on the back surface of the light guide plate, and the surface light source unit can be configured simply by laminating the light diffusion film on the light guide plate that can be easily and economically manufactured by a method such as molding, and the structure is simple. Can be converted.

FIG. 3 is a schematic sectional view showing another example of the light diffusion film. In this example, the light diffusion film 27
Has a laminated structure including a light diffusion layer 28 and a transparent resin layer 29 laminated on at least one surface of the light diffusion layer. And in order to impart ultraviolet absorption,
In this example, at least the transparent resin layer 29 contains an ultraviolet absorber. The light diffusion layer 28 is made of a plurality of resins having different refractive indexes, and is a continuous layer 28a.
It has a phase separation structure (or sea-island structure) in which dispersed phase particles 28b are dispersed.

In the light diffusing film having such a laminated structure, the light diffusing layer 28 can also be effectively protected from ultraviolet rays by laminating or disposing the transparent resin layer 29 on the light emitting surface of the light guide plate of the surface light source unit. Therefore, the leakage of ultraviolet rays can be reliably and stably prevented. Further, when the light diffusion layer is protected by the transparent resin layer, the disperse phase particles can be prevented from falling off or adhering, the scratch resistance and the production stability of the film can be improved, and the strength and handleability of the film can be improved.

In the light diffusion film of the present invention, the transmitted light may be isotropically diffused or anisotropically diffused. By anisotropically diffusing light, the brightness of the display surface can be improved with high uniformity even when viewed from a wide angle in the left-right direction or the vertical direction as a surface light source unit or device.

The anisotropic light diffusing sheet is capable of scattering incident light in the traveling direction of light, is not isotropically scattered, is strong in a predetermined direction, and even if the scattering angle in the predetermined direction becomes large, The film may have a higher scattering intensity than the scattering angle in the direction orthogonal to the predetermined direction.

FIG. 4 is a conceptual diagram for explaining the anisotropy of light diffusion. As shown in FIG. 4, the anisotropic light-diffusing film 37 is composed of a continuous phase 37a made of a resin and an anisotropic dispersed phase 37b dispersed in the continuous phase. Then, the anisotropy of light diffusion depends on the scattering angle θ and the scattered light intensity F.
In the scattering characteristic F (θ) showing the relationship with, when the scattering characteristic of the film in the X-axis direction is Fx (θ) and the scattering characteristic in the Y-axis direction orthogonal to the X-axis direction is Fy (θ), θ = 4-
The scattered light intensity characteristic satisfies Fy (θ) / Fx (θ)> 1.01 in the range of 30 °. The X-axis direction of the anisotropic light diffusion film 37 is usually the long axis direction of the dispersed phase 37b. Therefore, the X-axis direction of the anisotropic light diffusion film is the axial direction (X-axis direction) of the tubular light source of the surface light source unit.
Are arranged substantially parallel to or coincide with. The X-axis direction of the anisotropic light-diffusing film does not need to be completely aligned with the axial direction (X-axis direction) of the tubular light source of the surface light source unit, and for example, is oblique within a range of about ± 15 °. You may arrange | position toward a direction.

A preferable scattered light intensity characteristic is Fy (θ) /
Fx (θ) ≧ 1.1, especially ≧ 1.5. Note that Fy
The value of (θ) / Fx (θ) is usually 1.1 to 500 (for example, 10 to 500), preferably 15 to 500, and more preferably 50 to 500 (for example, 100 to 400).
It is a degree.

That is, the Fy (θ) in the Y-axis direction of the anisotropic light-diffusing film is strong up to the scattering angle θ of a considerably wide angle, and the Fx (θ) in the X-axis direction is attenuated at the scattering angle θ of a small angle. It has the feature of doing. The light diffusion film having such optical characteristics can make the brightness in the horizontal direction or the vertical direction uniform on the display surface of the display unit.

The transmissive display device (particularly the transmissive liquid crystal display device) of the present invention is a display unit (liquid crystal display unit or the like).
And the surface light source unit for illuminating this display unit. In this device, the anisotropic light diffusing film may be arranged in various directions, but when the horizontal direction of the display surface (liquid crystal display surface) is the Y axis, the anisotropic light diffusion film is It is preferable that the anisotropic light-diffusing film is arranged along the Y-axis (main light-scattering direction) or along the same direction. The Y-axis direction of the anisotropic light-diffusing film does not need to be completely aligned with the left-right direction (Y-axis direction) of the display unit.
It may be arranged in an oblique direction within a range of about °. By arranging the anisotropic light diffusion film in such a direction, the luminance distribution can be made uniform, and the angular dependence of the luminance with respect to the display surface can be reduced, so that the luminance in the left-right direction (horizontal direction) can be made uniform, and the standard such as TCO. Can be satisfied.

The scattering characteristic F (θ) is, for example, as shown in FIG.
It can be measured using a measuring device as shown in. This device is a laser light irradiation device (NIHON KAGAKU ENG NEO-20M) for irradiating the anisotropic light diffusion sheet 37 with laser light.
S) 38 and a detector 39 for measuring the intensity of the laser light transmitted through the anisotropic light diffusion sheet 37.
Then, the surface of the light diffusion sheet 37 is irradiated with laser light at 90 ° (perpendicularly), and the intensity (diffusion intensity) F of the light diffused by the film is measured with respect to the diffusion angle θ (plot). By doing so, the light scattering characteristics can be obtained.

In the anisotropic light-diffusing film, if the anisotropy of light scattering is high, the angular dependence of scattering in a predetermined direction can be further reduced, and thus the angular dependence of brightness can be further reduced. In the anisotropic diffusion sheet, when the angle (90 °) perpendicular to the display surface is set to 0 °, it is possible to suppress a decrease in brightness beyond an angle of 20 ° with respect to the display surface and an angle of 40 ° or more. .

Such characteristics can be expressed by the ratio of the brightness at a predetermined scattering angle (θ) to the front brightness of the display surface or the ratio of the brightness at two scattering angles (θ).
That is, when the light diffusion film or surface light source unit of the present invention is used, the value of the above ratio can be reduced. For example, the front brightness (N = 0) at an angle (θ = 0 °) perpendicular to the display surface.
(0 °)) and the brightness at an angle of 18 ° (N (18 °))
And the ratio of the brightness at an angle of 40 ° (N (40 °)) and the ratio of the brightness at an angle of 18 ° (N (18 °)) to the brightness at an angle of 40 ° (N (40 °)) are small. it can. By reducing these ratios, for example, by disposing an anisotropic scattering sheet on the prism sheet of the liquid crystal display device, it is possible to supply a transmissive liquid crystal display device suitable for a commercial monitor satisfying the TCO99 standard. .

In the surface light source device, the light diffusing film may be arranged in the light path emitted from the light emitting surface (emission surface) of the surface light source unit, that is, on the light emitting surface (emission surface) side of the surface light source unit. , If necessary, it may be arranged in a laminated form in which it is laminated on the light emitting surface (emission surface) using an adhesive,
It may be arranged between the emission surface of the surface light source unit and the display unit. The prism sheet is not particularly necessary, but it is useful for condensing diffused light and illuminating the display unit. When the prism sheet and the light diffusing sheet are used in combination, the prism sheet is usually arranged on the downstream side of the light path with respect to the light diffusing sheet.

The light-diffusing film has only to have light-diffusing properties and ultraviolet-absorbing properties, and is not limited to the form containing the ultraviolet-absorbing agent, and a coating film containing the ultraviolet-absorbing agent may be formed. The light-diffusing film can be composed of at least a light-diffusing layer, and as described above, it may be composed of a laminate of a light-diffusing layer and a transparent layer, and the transparent layer is not limited to a resin layer but various transparent bases. Materials such as glass can be used.

Further, the ultraviolet absorber can be contained in various layers constituting the light diffusing film. For example, it is blended in at least one of a layer having a light scattering property (light scattering layer) and a transparent resin layer. Alternatively, it may be contained in both layers. Further, in the light diffusion film having a laminated structure, not only one surface of the light scattering layer but also transparent resin layers may be laminated on both surfaces. The resin constituting the transparent resin layer may be the same as or different from the resin of the continuous phase and / or the dispersed phase constituting the light diffusing layer, as long as the adhesion and mechanical properties are not impaired. A resin that is the same or common (or the same system) as the resin of the continuous phase is preferably used.

The light diffusion layer comprises a continuous phase (resin continuous phase, matrix resin), a dispersed phase dispersed in the continuous phase (scattering factors such as particulate or fibrous dispersed phase) and, if necessary, an ultraviolet absorber. The continuous phase and the dispersed phase have different refractive indexes from each other, and are usually incompatible or hardly compatible with each other. The continuous phase and dispersed phase can usually be formed of transparent materials.

The resin forming the light diffusing film (the resin forming the continuous phase and / or the dispersed phase) includes a thermoplastic resin (olefin resin, cyclic olefin resin, halogen-containing resin (including fluorine resin), Vinyl alcohol resin, vinyl ester resin, vinyl ether resin,
(Meth) acrylic resin, styrene resin, polyester resin, polyamide resin, polycarbonate resin, thermoplastic polyurethane resin, polysulfone resin (polyether sulfone, polysulfone, etc.), polyphenylene ether resin (2,6-xylenol) Polymers, etc.), cellulose derivatives (cellulose esters,
Cellulose carbamates, cellulose ethers, etc.), silicone resins (polydimethylsiloxane, polymethylphenylsiloxane, etc.), rubbers or elastomers (polybutadiene, polyisoprene and other diene rubbers, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer) Coalesced, acrylic rubber, urethane rubber,
Etc.) and thermosetting resins (epoxy resin, unsaturated polyester resin, diallyl phthalate resin, silicone resin, etc.) and the like. The preferred resin is a thermoplastic resin.

Examples of the olefin resin include homopolymers or copolymers of C _2-6 olefins (ethylene, ethylene, ethylene-propylene copolymer and other ethylene resins, polypropylene, propylene-ethylene copolymer, propylene-
Polypropylene resin such as butene copolymer, poly (methylpentene-1), propylene-methylpentene copolymer, etc.), copolymer of C _2-6 olefin and copolymerizable monomer (ethylene-vinyl acetate) Copolymer, ethylene-vinyl alcohol copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid copolymer or a salt thereof (for example, ionomer resin), ethylene-
Examples thereof include copolymers such as (meth) acrylic acid ester copolymers. As alicyclic olefin resins, cyclic olefins (norbornene, dicyclopentadiene, etc.)
Homopolymer or copolymer (for example, a polymer having a sterically rigid alicyclic hydrocarbon group such as tricyclodecane), a copolymer of the cyclic olefin and a copolymerizable monomer (ethylene- Norbornene copolymer, propylene-norbornene copolymer, etc.) and the like. The alicyclic olefin-based resin is, for example, a product name “ARTO (ARTO
N) ”, product name“ ZEONEX ”, etc.

Examples of the halogen-containing resin include vinyl halide resins (polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, homopolymers of halogen-containing monomers such as polyvinyl fluoride, tetrafluoroethylene-hexa). Fluoropropylene copolymers, copolymers of halogen-containing monomers such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, vinyl chloride-vinyl acetate copolymers, vinyl chloride- (meth) acrylic acid ester copolymers , A copolymer of a halogen-containing monomer such as tetrafluoroethylene-ethylene copolymer and a copolymerizable monomer), a vinylidene halide resin (polyvinylidene chloride, polyvinylidene fluoride, vinylidene chloride- ( (Meth) acrylic acid ester copolymer Halogen-containing vinylidene monomer and other monomers, a copolymer) and the like.

Derivatives of vinyl alcohol resins include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. As vinyl ester resin,
Homo- or copolymers of vinyl ester monomers (polyvinyl acetate, vinyl propionate, etc.), copolymers of vinyl ester monomers and copolymerizable monomers (vinyl acetate-ethylene copolymers) , Vinyl acetate-vinyl chloride copolymer, vinyl acetate- (meth) acrylic acid ester copolymer, etc.) or their derivatives. Derivatives of vinyl ester resins include polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyvinyl acetal resins, and the like.

Examples of vinyl ether resins include vinyl C such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether and vinyl t-butyl ether.
_1-10 Alkyl ether homo- or copolymers, vinyl C
Examples thereof include copolymers of _1-10 alkyl ether and a copolymerizable monomer (such as vinyl alkyl ether-maleic anhydride copolymer).

As the (meth) acrylic resin, a homopolymer or copolymer of a (meth) acrylic monomer and a copolymer of a (meth) acrylic monomer and a copolymerizable monomer can be used. . Examples of the (meth) acrylic monomer include (meth) acrylic acid; methyl (meth) acrylate, (meth)
Ethyl acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. C _1-10 alkyl (meth) acrylate; aryl (meth) acrylate such as phenyl (meth) acrylate; hydroxyalkyl (meth) acrylate such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate; glycidyl (Meth) acrylate; N, N-dialkylaminoalkyl (meth) acrylate; (meth) acrylonitrile; (meth) acrylate having an alicyclic hydrocarbon group such as tricyclodecane. The copolymerizable monomer, the styrene-based monomer, vinyl ester-based monomer, maleic anhydride,
Examples include maleic acid and fumaric acid. These monomers can be used alone or in combination of two or more.

Examples of the (meth) acrylic resin include poly (meth) acrylic acid esters such as polymethylmethacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylic acid. Examples thereof include ester copolymers, methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymers, and (meth) acrylic acid ester-styrene copolymers (MS resin, etc.). Preferred (meth) acrylic resins include poly (meth) acrylates such as poly (meth) acrylate.
Acrylic acid C _1-6 alkyl, in particular a main component methyl methacrylate (50 to 100 wt%, preferably 70 to 100
Methyl methacrylate-based resin is used.

Examples of the styrene resin include homopolymers or copolymers of styrene monomers (polystyrene, styrene-α-methylstyrene copolymer, styrene-vinyltoluene copolymer, etc.), styrene monomers and others. And a copolymer with a polymerizable monomer ((meth) acrylic monomer, maleic anhydride, maleimide monomer, dienes, etc.).
Examples of the styrene-based copolymer include a styrene-acrylonitrile copolymer (AS resin), a copolymer of styrene and a (meth) acrylic monomer [styrene-methyl methacrylate copolymer, styrene-methacrylic acid Styrene- (meth) acrylic acid ester copolymers such as methyl- (meth) acrylic acid ester copolymer, styrene-methyl methacrylate- (meth) acrylic acid copolymer], styrene-maleic anhydride copolymer, etc. Is mentioned. Preferred styrene resins include polystyrene, copolymers of styrene and (meth) acrylic monomers [copolymers containing styrene and methyl methacrylate as main components, such as styrene-methyl methacrylate copolymer], Examples include AS resins and styrene-butadiene copolymers.

As the polyester resin, an aromatic polyester using an aromatic dicarboxylic acid such as terephthalic acid (such as poly C _2-4 alkylene terephthalate such as polyethylene terephthalate and polybutylene terephthalate and poly C _2-4 alkylene naphthalate) is used. Homopolyester, a C _2-4 alkylene arylate unit (C _2-4 alkylene terephthalate and / or C _2-4 alkylene naphthalate unit) as a main component (for example, 50 mol% or more, preferably 75 to 100 mol%, and further preferably Is 80-100
Mol%) and a liquid crystalline polyester. As copolyester,
Among the constituent units of poly C _2-4 alkylene arylate, C
Part of _2-4 alkylene glycol is polyoxy C _2-4 alkylene glycol, C _6-10 alkylene glycol, alicyclic diol (cyclohexanedimethanol, hydrogenated bisphenol A, etc.), diol having aromatic ring (fluorenone side chain) With 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, bisphenol A, bisphenol A-alkylene oxide adduct, etc., and a part of the aromatic dicarboxylic acid, phthalic acid , A copolyester substituted with an asymmetric aromatic dicarboxylic acid such as isophthalic acid and an aliphatic C _6-12 dicarboxylic acid such as adipic acid. Polyester resins include polyarylate resins, aliphatic polyesters using aliphatic dicarboxylic acids such as adipic acid, and homo- or copolymers of lactones such as ε-caprolactone. Preferred polyester resins are usually non-crystalline, such as non-crystalline copolyesters (eg C _2-4 alkylene arylate copolyesters).

As the polyamide resin, nylon 4 is used.
6, Nylon 6, Nylon 66, Nylon 610, Nylon 612, Nylon 11, Nylon 12 and other aliphatic polyamides, dicarboxylic acids (eg, terephthalic acid, isophthalic acid, adipic acid, etc.) and diamines (eg, hexamethylene diamine, meta Xylylenediamine) and a polyamide (eg, an aromatic polyamide such as xylylenediamine adipate (MXD-6)). The polyamide resin may be a lactam homopolymer or copolymer such as ε-caprolactam, and may be a copolyamide as well as a homopolyamide.

Polycarbonate resins include aromatic polycarbonates based on bisphenols (bisphenol A, etc.), aliphatic polycarbonates such as diethylene glycol bisallyl carbonate, and the like.

Among the cellulose derivatives, examples of the cellulose ester include aliphatic organic acid esters (cellulose acetate such as cellulose diacetate, cellulose triacetate; cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate). _C1-6 organic acid ester such as rate), aromatic organic acid ester ( _C7-12 aromatic carboxylic acid ester such as cellulose phthalate, cellulose benzoate), inorganic acid ester (for example,
Cellulose phosphate, cellulose sulfate, etc.)
It may be a mixed acid ester such as acetic acid / nitric acid cellulose ester. Cellulose derivatives include cellulose carbamates (eg, cellulose phenyl carbamate), cellulose ethers (eg, cyanoethyl cellulose; hydroxy C _2-4 alkyl cellulose such as hydroxyethyl cellulose and hydroxypropyl cellulose; C _1- such as methyl cellulose and ethyl cellulose). ₆ alkyl cellulose; carboxymethyl cellulose or salts thereof, benzyl cellulose, acetyl alkyl cellulose, etc.) are also included.

The resin component may be modified (for example, rubber modified) if necessary. Alternatively, a continuous phase matrix may be formed from the resin component, and the dispersed phase component may be grafted or block copolymerized on the matrix resin. Examples of such a polymer include a rubber block copolymer (styrene-butadiene copolymer (SB
Resin)), rubber-grafted styrene-based resin (acrylonitrile-butadiene-styrene copolymer (ABS resin), etc.) and the like.

The dispersed phase (light scattering factor) can be formed by adding inorganic or organic fine particles or fibers to the matrix resin, adding a resin having a different refractive index to the matrix resin, and kneading. As the inorganic or organic fine particles,
Inorganic particles such as inorganic oxides (silica, alumina, titanium oxide, etc.), carbonates (calcium carbonate, etc.), sulfates (barium sulfate, etc.), natural minerals or silicates (talc, etc.); crosslinked polystyrene beads, etc. Examples thereof include styrene resin, crosslinked acrylic resin such as crosslinked polymethylmethacrylate, and crosslinked resin particles such as crosslinked guanamine resin. The fibrous dispersed phase includes organic fibers, inorganic fibers and the like. Organic fibers are heat resistant organic fibers, for example,
It may be aramid fiber, wholly aromatic polyester fiber, polyimide fiber or the like. As the inorganic fiber, for example,
Examples thereof include fibrous fillers (inorganic fibers such as glass fibers, silica fibers, alumina fibers, zirconia fibers) and flaky fillers (mica etc.).

Preferred components constituting the continuous phase or dispersed phase include olefin resins, (meth) acrylic resins, styrene resins, polyester resins, polyamide resins, polycarbonate resins and the like. The resin forming the continuous phase and / or the dispersed phase may be crystalline or amorphous, and the continuous phase and the dispersed phase may be formed of an amorphous resin. In a preferred embodiment, crystalline resin and amorphous resin can be combined. That is, one of the continuous phase and the dispersed phase (for example, the continuous phase) can be made of a crystalline resin, and the other phase (for example, the dispersed phase) can be made of an amorphous resin.

Examples of the crystalline resin include olefin resins (polypropylene, polypropylene resins such as polypropylene and propylene-ethylene copolymer having a propylene content of 90 mol% or more, poly (methylpentene-1), etc.), vinylidene resins (chlorinated resin). Vinylidene-based resins, etc.), aromatic polyester-based resins (polyalkylene arylate homopolyesters such as polyalkylene terephthalates and polyalkylene naphthalates, copolyesters having an alkylene arylate unit content of 80 mol% or more, liquid crystalline aromatic polyesters, etc.) Examples thereof include polyamide resins (eg, aliphatic polyamide having short chain segments such as nylon 46, nylon 6, nylon 66). These crystalline resins can be used alone or in combination of two or more kinds.
The crystallinity of the crystalline resin (crystalline polypropylene resin or the like) is, for example, about 10 to 80%, preferably 20 to
It is about 70%, more preferably about 30 to 60%.

As the resin constituting the continuous phase, a resin having high transparency and heat stability is usually used. The resin forming the preferred continuous phase is a crystalline resin having a high fluidity as a melting property. By combining such a resin with a resin constituting the dispersed phase, it is possible to form a uniform compound with the dispersed phase. A resin having a high melting point or glass transition temperature as a resin constituting the continuous phase (particularly, a crystalline resin having a high melting point, for example, a melting point or glass transition temperature of 130 to 28).
If a resin having a temperature of about 0 ° C., preferably about 140 to 270 ° C., and more preferably about 150 to 260 ° C.) is used, the heat stability and the film processability are excellent, and the draw-down rate in the melt film formation is increased. It is easy to form a film by melt film formation. Therefore, the alignment treatment (or uniaxial stretching treatment) for improving the anisotropic scattering property can be performed at a relatively high temperature (for example, about 130 to 150 ° C.), the processing is easy, and the dispersed phase is easily formed. Can be oriented. Moreover,
Wide temperature range (for example, room temperature to 80 ° C)
And stable. Also, crystalline resins (such as crystalline polypropylene resins) are generally inexpensive. Preferred crystalline resins include crystalline polypropylene resins that are inexpensive and have high thermal stability.

As the non-crystalline resin, for example, a vinyl polymer (ionomer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid ester copolymer,
Polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, vinyl alcohol homopolymers such as vinyl monomer homopolymers or copolymers), (meth) acrylic resins (polymethylmethacrylate, methacryl) Methyl acid-
Styrene copolymer (MS resin etc.), styrene resin (polystyrene, AS resin, styrene-methyl methacrylate copolymer etc.), polycarbonate polymer, amorphous polyester resin (aliphatic polyester, diol component and / Or polyalkylene arylate copolyester in which a part of the aromatic dicarboxylic acid component is substituted, polyarylate resin, etc., polyamide resin (aliphatic polyamide having long chain segment, non-crystalline aromatic polyamide), thermoplastic elastomer (Polyester elastomer, polyolefin elastomer, polyamide elastomer, styrene elastomer, etc.) can be exemplified. In the amorphous polyester resin, the polyalkylene arylate copolyester is a part of the diol component (C _2-4 alkylene glycol) and / or the aromatic dicarboxylic acid component (terephthalic acid, naphthalene dicarboxylic acid) (for example, 10 ~ 80 mol%, preferably 2
0-80 mol%, more preferably about 30-75 mol%), (poly) oxyalkylene glycol such as diethylene glycol and triethylene glycol, cyclohexanedimethanol, phthalic acid, isophthalic acid,
Copolyesters using at least one selected from aliphatic dicarboxylic acids (such as adipic acid) are included. These non-crystalline resins can be used alone or in combination of two or more.

As the resin constituting the dispersed phase, a resin having high transparency and being easily deformed at an orientation treatment temperature such as a uniaxial stretching temperature and having a practical thermal stability is used.
In particular, when a resin having a melting point or glass transition temperature lower than that of the continuous phase is used, the aspect ratio of the dispersed phase particles can be easily increased by the orientation treatment such as uniaxial stretching. Incidentally, the melting point or glass transition temperature of the resin constituting the dispersed phase is often lower than the resin constituting the continuous phase,
For example, about 50 to 180 ° C., preferably 60 to 170
The resin may have a temperature of about 70 ° C, more preferably about 70 to 150 ° C.

Among the non-crystalline resins constituting the dispersed phase, at least one resin selected from non-crystalline copolyester resin and polystyrene resin is preferable. When the dispersed phase is composed of an amorphous copolyester resin, not only is the transparency high, but the glass transition temperature is, for example, about 80.
Since the temperature is about C, the dispersed phase can be easily deformed at the orientation treatment temperature such as uniaxial stretching and can be stabilized in a predetermined temperature range (for example, room temperature to about 80 ° C) even after molding.
In addition, an amorphous copolyester (for example, ethylene glycol / cyclohexanedimethanol = 10/90 to 6)
A polyethylene terephthalate copolyester using a diol component of 0/40 (mol%), particularly about 25/75 to 50/50 (mol%), and 9,9-bis (4- (2-hydroxy) having a fluorenone side chain. (Ethoxy) phenyl) fluorene (such as a copolyester using a diol component) has a high refractive index (for example, about 1.57) and is relatively well compounded with the crystalline resin (such as a polypropylene resin). .

Since the polystyrene resin has a high refractive index and transparency and a high glass transition temperature of about 100 to 130 ° C., an anisotropic scattering sheet excellent in heat resistance can be prepared.
In addition, inexpensive polystyrene-based resin is a suitable anisotropic material because it has a relatively small ratio to the crystalline resin (polypropylene-based resin, etc.) as the resin for the continuous phase, and has a relatively low draw-down ratio for melt film formation. A sex scattering sheet can be prepared.
In addition, when the film is melted and then rolled, it exhibits very high anisotropy.

In order to impart light diffusibility, the continuous phase and the dispersed phase are composed of components having different refractive indexes. The difference in refractive index between the continuous phase and the dispersed phase is, for example, 0.001 or more (for example, about 0.001 to 0.3), preferably about 0.01 to 0.3, and more preferably 0.01 to 0.3.
It is about 0.1.

Examples of the combination of such resins include the following combinations.

(1) Combination of olefin resin (particularly propylene resin) and at least one selected from acrylic resin, styrene resin, polyester resin, polyamide resin, and polycarbonate resin (2) Combination of styrene resin and at least one selected from polyester resin, polyamide resin, and polycarbonate resin (3) Combination of polyester resin and at least one selected from polyamide resin and polycarbonate resin As a preferable combination of the crystalline resin forming the continuous phase and the amorphous resin forming the dispersed phase, for example, a crystalline polyolefin resin (such as a crystalline polypropylene resin)
And an amorphous polyester (polyalkylene terephthalate copolyester or other polyalkylene arylate copolyester) and at least one resin selected from polystyrene resins.

In the light diffusing layer, the ratio of the continuous phase and the dispersed phase depends on the kind of resin, melt viscosity, light diffusivity and the like.
For example, former / latter (weight ratio) = 99/1 to 30/70
(For example, 95/5 to 40/60 (weight ratio)), preferably 99/1 to 50/50 (for example, 95/5 to 5)
0/50 (weight ratio)), more preferably 99/1
It can be appropriately selected from the range of about 75/25.

The light-scattering sheet may contain a compatibilizer, if necessary. The use of a compatibilizer can improve the miscibility and affinity between the continuous phase and the disperse phase, can prevent the generation of defects (defects such as voids) even when the film is oriented, and makes the film transparent. It is possible to prevent deterioration of sex.
Furthermore, the adhesiveness between the continuous phase and the dispersed phase can be enhanced, and even if the film is uniaxially stretched, the adhesion of the dispersed phase to the stretching device can be reduced.

The compatibilizer can be selected from conventional compatibilizers depending on the types of the continuous phase and the dispersed phase, and examples thereof include an oxazoline compound and a modifying group (carboxyl group, acid anhydride group, epoxy group, oxazolinyl group, etc.). Modified resin, a diene- or rubber-containing polymer [eg, a diene monomer homopolymer or a diene copolymer obtained by copolymerization with a copolymerizable monomer (such as an aromatic vinyl monomer)] Polymers (random copolymers, etc.); Diene-based graft copolymers such as acrylonitrile-butadiene-styrene copolymers (ABS resins); Styrene-butadiene (SB) block copolymers, hydrogenated styrene-butadiene (SB) blocks Copolymer, hydrogenated styrene-butadiene-styrene block copolymer (SEBS), hydrogenated (styrene-ethylene / butylene- Styrene) block copolymer diene block copolymer or hydrogenated product thereof, such as, etc.], etc. The like modifying groups (epoxy group) modified with diene or rubber-containing polymer can be exemplified. These compatibilizers can be used alone or in combination of two or more.

As the compatibilizing agent, a polymer (random, block or graft copolymer) having the same or common component as the constituent resin of the polymer blend system, or an affinity for the constituent resin of the polymer blend system is usually used. A polymer (random, block or graft copolymer) or the like is used.

Examples of the diene monomer include conjugated dienes such as butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene. , C _4-20 conjugated dienes which may have a substituent such as phenyl-1,3-butadiene. The conjugated dienes may be used alone or in combination of two or more. Of these conjugated dienes, butadiene and isoprene are preferred. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene (p-methylstyrene, etc.), pt-butylstyrene, divinylbenzenes, and the like. Of these aromatic vinyl monomers,
Styrene is preferred. These monomers can be used alone or in combination of two or more.

The modification is carried out by modifying a monomer corresponding to a modifying group (for example, a carboxyl group-containing monomer such as (meth) acrylic acid when modifying a carboxyl group, maleic anhydride or an ester group modifying when modifying an acid anhydride group). Then (meth) acrylic monomer, maleimide group modified maleimide monomer,
The epoxy modification can be performed by copolymerizing an epoxy group-containing monomer such as glycidyl (meth) acrylate. Further, the epoxy modification may be carried out by epoxidizing the unsaturated double bond.

Preferred compatibilizers are unmodified or modified diene copolymers, especially modified block copolymers (eg epoxidized styrene-butadiene-styrene (SB
S) an epoxidized diene-based block copolymer such as a block copolymer or an epoxy-modified diene-based block copolymer). The epoxidized diene block copolymer is
Not only is the transparency high, but the softening temperature is relatively high at about 70 ° C., and the resin can be compatibilized in many combinations of the continuous phase and the dispersed phase, and the dispersed phase can be uniformly dispersed.

The block copolymer can be composed of, for example, a conjugated diene block or a partially hydrogenated block thereof and an aromatic vinyl block. In the epoxidized diene block copolymer, some or all of the double bonds of the conjugated diene block are epoxidized. The ratio (weight ratio) of the aromatic vinyl block and the conjugated diene block (or its hydrogenated block) is, for example, former / latter = 5/95 to 80/20 (for example, 25/75 to
80/20), more preferably 10/90 to 70
/ 30 (for example, about 30/70 to 70/30), and usually about 50/50 to 80/20. An epoxidized block copolymer having an aromatic vinyl block (styrene block etc.) content of about 60 to 80% by weight has a relatively high refractive index (for example, about 1.5%).
7) In addition, since it has a refractive index similar to that of the resin of the dispersed phase (such as amorphous copolyester), the dispersed phase can be uniformly dispersed while maintaining the light scattering property of the dispersed phase resin.

The number average molecular weight of the block copolymer is, for example, about 5,000 to 1,000,000, preferably about 7,000 to 900,000, and more preferably 1.
It can be selected from the range of about 10,000 to 800,000. The molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)] is, for example, 10 or less (about 1 to 10), preferably about 1 to 5.

The block copolymer has a linear molecular structure,
It may be branched, radial or a combination thereof. Examples of the block structure of the block copolymer include a multiblock structure such as a monoblock structure and a teleblock structure, a trichain radial teleblock structure, and a tetrachain radial teleblock structure. As such a block structure, when the aromatic diene block is X and the conjugated diene block is Y, for example, XY type, XYX type, YXY type,
X-Y-X-Y type, X-Y-X-Y-X type, Y-X-Y
-X-Y-type, (X-Y-) ₄ Si type, (Y-X-) ₄ Si
A type etc. can be illustrated.

The proportion of epoxy groups in the epoxidized diene block copolymer is not particularly limited, but the oxygen concentration of oxirane is, for example, 0.1 to 8% by weight, preferably 0.5 to 6% by weight, More preferably 1 to 5% by weight
It is a degree. The epoxy equivalent of the epoxidized block copolymer (JIS K 7236) is, for example, 300 to 10.
It may be about 00, preferably about 500 to 900, and more preferably about 600 to 800.

The refractive index of the compatibilizing agent (epoxidized block copolymer, etc.) is about the same as that of the dispersed phase resin (for example, the difference in refractive index from the dispersed phase resin is about 0 to 0.01,
Preferably about 0 to 0.005).

The epoxidized block copolymer is prepared by using a diene block copolymer (or a partially hydrogenated block copolymer) by a conventional epoxidation method, for example, in an inert solvent, an epoxidizing agent ( It can be produced by epoxidizing the block copolymer with peracids, hydroperoxides, etc.).

The amount of the compatibilizer used can be selected from the range of, for example, 0.1 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, based on the entire resin composition. .

In the preferred light diffusing film, the proportions of the continuous phase, the dispersed phase, and the compatibilizer are, for example, as follows.

(1) Continuous phase / dispersed phase (weight ratio) = 99 /
About 1 to 50/50, preferably 98/2 to 60/40
Degree, more preferably about 90/10 to 60/40,
Especially about 80/20 to 60/40 (2) Dispersed phase / Compatibilizer (weight ratio) = 99/1 to 50 /
Approximately 50, preferably approximately 99/1 to 70/30, more preferably approximately 98/2 to 80/20 When each component is used in such a ratio, pellets of each component are prepared without compounding each component in advance. Even if it is directly melt-kneaded, the disperse phase can be uniformly dispersed, a void can be prevented from being generated by an orientation treatment such as uniaxial stretching, the transmittance is high, and the ultraviolet-absorbing light-diffusing film has anisotropy. Can be obtained.

More specifically, for example, (a) a crystalline polypropylene resin as a continuous phase, an amorphous copolyester resin as a dispersed phase, and an epoxidized SBS (styrene-butadiene-styrene) as a compatibilizer. Block copolymer), continuous phase / dispersed phase = 99/1 to 50/50
(Weight ratio) (especially 80/20 to 60/40 (weight ratio)), dispersed phase / compatibilizer = 99/1 to 50/50 (weight ratio) (especially 98/2 to 80/20 (weight ratio) )) Contained in the resin composition, (b) a crystalline polypropylene resin as a continuous phase, a polystyrene resin as a dispersed phase,
Epoxidized SBS as a compatibilizing agent, continuous phase / dispersed phase = 99/1 to 50/50 (weight ratio) (especially 90/10 to 10/10)
70/30 (weight ratio)), dispersed phase / compatibilizer = 99/1
-50/50 (weight ratio) (especially 99.5 / 0.5-90)
/ 10 (weight ratio)), it is easy to compound into a compound, and only by feeding the raw materials, it is possible to perform melt film formation while compounding, and to obtain light without voids even when uniaxially stretched. A diffusion film can be formed.

Examples of the ultraviolet absorber include benzotriazole type ultraviolet absorbers [N-hydroxyphenylbenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-). 5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5) '-Methylphenyl) -5
-Chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3',
5'-di-t-amylphenyl) benzotriazole, 2
-(2'-hydroxy-4'-octyloxyphenyl) benzotriazole, 2,2-methylenebis [4-
(1,1,3,3-tetramethylbutyl) -6- (2H
-Benzotriazol-2-yl) phenol], [2
-(2'-hydroxy-5'-methacryloxyphenyl) -2H-benzotriazole], etc.], benzophenone-based ultraviolet absorber [2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-alkoxy] Benzophenone (2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-
Octyloxybenzophenone, 2-hydroxy-4-
Dodecyloxybenzophenone, bis (2-methoxy-
4-hydroxy-5-sulfobenzophenone), 2-hydroxy-4-methoxy-5-sulfobenzophenone, etc.), 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, bis (2-methoxy-4-hydroxy-). 5-benzoylphenylmethane), etc.], benzoate-based UV absorber [2,4-di-t-butylphenyl-
3,5-di-t-butyl-4-hydroxybenzoate, etc.], salicylic acid-based UV absorbers [phenyl salicylate, p-t-butylphenyl salicylate, p-octylphenyl salicylate, etc.], triazine-based UV absorbers [2- ( 4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxy-phenol and the like] and the like. These ultraviolet absorbers can be used alone or in combination of two or more. Preferred UV absorbers are benzotriazole-based UV absorbers and benzophenone-based UV absorbers.

The ultraviolet absorber can be selected according to the type of resin, and a compound having compatibility or solubility with the resin is usually used. When the light diffusion layer contains a UV absorber, the UV absorber is usually mainly dissolved or finely dispersed in the continuous phase.

The amount of the ultraviolet absorber used can be selected from the range of, for example, about 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin constituting the layer containing the ultraviolet absorber or the continuous phase, and is usually 0. 1-5 parts by weight, preferably 0.2-2.
It is about 5 parts by weight, and more preferably about 0.5 to 2 parts by weight. The amount of the ultraviolet absorber used is usually selected within a range in which bleed out does not occur.

The ultraviolet absorber may be used in combination with various stabilizers (antioxidants, heat stabilizers), especially light stabilizers for preventing deterioration of the resin. Examples of the stabilizer include an ultraviolet stabilizer (nickel bis (octylphenyl) sulfide, [2,2-thiobis (4-t-octylphenolate)]-n-butylamine nickel, nickel-dibutyldithiocarbamate, etc.), a hindered amine-based light stabilizer. Stabilizer ([bis (2,2,6,6-tetramethyl 4-
Piperidyl) sebacate and the like]) and the like.

Further, as long as the light-scattering property is not adversely affected, the ultraviolet-absorbing fine particles (for example, inorganic fine particles such as fine particles of zinc oxide and titanium oxide) are in a range that does not impair the light-scattering property and the light-transmitting property (for example, , 0.01-1% by weight
A small amount) may be used together.

Further, the light diffusion film may contain a conventional additive such as a plasticizer, an antistatic agent, a flame retardant and a filler.

In the light diffusion film, the dispersed phase particles are
The spherical particles may have a ratio of the average length L of the major axis to the average length W of the minor axis (average aspect ratio, L / W) of 1. Further, in the anisotropic light diffusion film, the aspect ratio is larger than 1, and the major axis direction of the dispersed phase particles is oriented in the X axis direction of the film. A preferable average aspect ratio (L / W) is, for example, 1 to 1000 (for example, 2 to 1).
000), preferably about 5 to 1000, more preferably about 5 to 500 (for example, 20 to 500), and usually about 50 to 500 (particularly 70 to 300). Such dispersed phase particles may have a football shape (spheroidal shape or the like), a fiber shape, a rectangular shape, or the like. The larger the aspect ratio, the higher the anisotropic light scattering property can be.

The average length L of the long axis of the dispersed phase is, for example, about 0.1 to 200 μm (eg, 1 to 100 μm).
Degree), preferably about 1 to 150 μm (for example, 1 to
About 80 μm), especially about 2 to 100 μm (for example, 2
It is about 10 to 100 μm), and usually about 10 to 100 μm (for example, 30 to 100 μm, particularly 10 to 50 μm). Further, the average length W of the minor axis of the dispersed phase is, for example,
0.1 to 10 μm, preferably 0.15 to 5 μm
(For example, 0.5 to 5 μm), and more preferably 0.2 to 2 μm (for example, 0.5 to 2 μm). The average length W of the minor axis of the dispersed phase is, for example, 0.01 to
It may be about 0.5 μm, preferably about 0.05 to 0.5 μm, and more preferably about 0.1 to 0.4 μm.

The orientation coefficient of the dispersed phase particles is, for example, 0.7.
Or more (about 0.7 to 1), preferably about 0.8 to 1,
More preferably, it may be about 0.9 to 1. The higher the orientation coefficient of the dispersed phase particles, the higher the anisotropy can be imparted to the scattered light. The orientation coefficient can be calculated based on the following formula.

Orientation coefficient = (3 <cos ² θ> −1) / 2 In the formula, θ represents the angle between the major axis of the particulate dispersed phase and the X axis of the film (the major axis and the X axis are If parallel, θ = 0
)), <Cos ² θ> represents the average of cos ² θ calculated for each dispersed phase particle and is represented by the following formula.

<Cos ² θ> = ∫n (θ) · cos ² θ · dθ (where n (θ) is the proportion (weight) of the dispersed phase particles having the angle θ in the total dispersed phase particles) The anisotropic light diffusing film (shown) may have a directionality of diffused light. That is,
Having directivity means that there is an angle at which the scattering intensity has a maximum in the directions in which the anisotropic diffused light has strong scattering. When the diffused light has directivity, when the diffused light intensity F is plotted against the diffusion angle θ in the measuring device of FIG. 5, the plot curve shows a specific diffusion angle θ.
Has a maximum or a shoulder (in particular, an inflection point such as a maximum) in the range (angle range excluding θ = 0 °).

When imparting directivity to the light diffusion film,
The refractive index difference between the continuous phase resin and the dispersed phase particles is, for example,
About 0.005-0.2, preferably 0.01-0.1
The average length of the long axis of the dispersed phase particles is, for example,
It is about 1 to 100 μm, preferably about 5 to 50 μm. The aspect ratio is, for example, 10 to 300 (for example,
20 to 300), preferably about 50 to 200, and may be about 40 to 300.

The thickness of the light diffusion film is 3 to 300 μm.
Degree, preferably 5 to 200 μm (for example, 30 to 20
0 μm), more preferably 5 to 100 μm (for example, 50 to 100 μm). The total light transmittance of the light scattering sheet is, for example, 85% or more (85 to 10).
0%), preferably about 90 to 100%, more preferably about 90 to 95%.

In the light-diffusing film having a laminated structure, the transparent resin forming the transparent resin layer can be selected from the resins exemplified above, but in order to enhance heat resistance and blocking resistance, a heat resistant resin (glass transition temperature or A resin having a high melting point) or a crystalline resin is preferable. The glass transition temperature or melting point of the resin forming the transparent resin layer may be similar to the glass transition temperature or melting point of the resin forming the continuous phase, for example, about 130 to 280 ° C., preferably 1
40 to 270 ° C, more preferably 150 to 260
It may be about C.

The thickness of the transparent resin layer may be the same as that of the light scattering sheet. For example, the thickness of the light scattering layer is 3 to
When the thickness is about 300 μm, the thickness of the transparent resin layer is 3 to 150.
It can be selected from about μm. The thickness ratio of the light diffusion layer and the transparent resin layer is, for example, light diffusion layer / transparent resin layer = 5/95.
To about 99/1, preferably about 50/50 to 99/1, and more preferably about 70/30 to 95/5. The thickness of the laminated film is, for example, about 6 to 600 μm, preferably about 10 to 400 μm, and more preferably about 20 to 250 μm.

The surface of the light diffusing film may be coated with a release agent such as silicone oil or may be subjected to corona discharge treatment as long as the optical characteristics are not impaired. further,
The light diffusing film having anisotropy may be provided with an uneven portion extending in the X-axis direction of the film (long-axis direction of the dispersed phase). By forming such uneven portions, it is possible to impart a higher anisotropic light scattering property to the film.

[Production Method of Light Diffusing Film] The light diffusing film can be produced by combining a resin, a light scattering component and an ultraviolet absorber. For example, it can be produced by a coating method in which a composition composed of an ultraviolet absorber, a light scattering component and a binder resin is applied on a substrate film, or an extrusion laminating method in which the composition is laminated. Further, the light-diffusing film having a single-layer structure is produced by molding a resin composition containing a resin, a light-scattering component and an ultraviolet absorber using a conventional film molding method such as a casting method or an extrusion molding method. it can.

A light diffusing film having a laminated structure composed of a light diffusing layer and a transparent resin layer laminated on at least one surface of the light diffusing layer is composed of components corresponding to the light diffusing layer. A resin composition and a resin composition composed of components corresponding to the transparent resin layer are co-extruded,
It can be formed by a coextrusion molding method of forming a film, a method of laminating one layer prepared in advance with the other layer by extrusion lamination, a dry laminating method of laminating a light diffusion layer and a transparent resin layer which are respectively prepared. As described above, it is preferable that at least the resin composition corresponding to the transparent resin layer contains an ultraviolet absorber.

The anisotropic light diffusing film can be obtained by dispersing and orienting the components (resin component, fibrous component, etc.) constituting the dispersed phase in the resin constituting the continuous phase. For example, the resin forming the continuous phase, the ultraviolet absorber, and the components forming the disperse phase (resin component, fibrous component, etc.) can be used, if necessary, by a conventional method (eg, melt blending method, tumbler method, etc.). Blend, melt mix, T
The dispersed phase can be dispersed by extruding from a die or ring die to form a film.

The orientation treatment of the dispersed phase can be performed, for example, by
(1) A method of forming a film while drawing an extruded sheet,
(2) A method of uniaxially stretching the extruded sheet, (3) A method of combining the method (1) and the method (2), and the like. Note that (4) a light diffusion film having anisotropy can also be formed by solution-blending the above components and forming a film by a casting method or the like.

The melting temperature is a temperature above the melting point of the resin component (continuous phase resin, dispersed phase resin), for example, 150 to 290.
C., preferably about 200 to 260.degree. The draw ratio (draw magnification) is, for example, about 2 to 40 times, preferably about 5 to 30 times, more preferably about 7 to 20 times. The draw ratio is, for example, about 1.1 to 50 times (for example, about 3 to 50 times), preferably about 1.5 to 30 times (for example, about 5 to 30 times).

When a draw and a draw are combined, the draw ratio may be, for example, about 2 to 10 times, preferably about 2 to 5 times, and the draw ratio is, for example,
1.1 to 20 times (eg, 2 to 20 times), preferably 1.5 to 10 times (eg, 3 to 10 times)
May be

A method for easily increasing the aspect ratio of the dispersed phase is to use a film (for example, a film formed and cooled).
Uniaxially stretching is included. The uniaxial stretching method is not particularly limited, and for example, a method of pulling both ends of the solidified film (pull stretching), a pair of rolls (2
Multiple rolls (for example, 2 rolls) are arranged in parallel, the film is inserted into each of the two rolls, and the film is stretched between the two rolls on the feeding side and the two rolls on the feeding side. A method of stretching by making the feeding speed of the film of the two rolls on the side higher than that of the two rolls on the feeding side (inter-roll stretching), inserting the film between a pair of rolls facing each other, and rolling the film by the roll pressure. A rolling method (roll rolling) and the like can be mentioned.

Preferred uniaxial stretching methods include methods that facilitate mass production of the film, such as roll-to-roll stretching and roll rolling. It is used as a method for producing a retardation film. Especially by roll rolling, not only the amorphous resin but also the crystalline resin can be easily stretched.
That is, usually, when the resin sheet is uniaxially stretched, the neck-in in which the thickness and width of the film are locally reduced is likely to occur, whereas the roll-in can prevent the neck-in and stabilize the stretching process of the film. it can. And, since there is little decrease in the film width before and after stretching, and the thickness in the width direction can be made uniform, the light scattering characteristics can be made uniform in the width direction of the film, the product quality can be easily maintained, and the film usage rate ( The yield) can also be improved. Furthermore, the draw ratio can be set widely. In the case of roll rolling, since the film width can be maintained before and after stretching, the reciprocal of the reduction rate of the film thickness and the stretching ratio become substantially equal.

The rolling pressure is, for example, 1 × 10 ⁴
˜1 × 10 ⁷ N / m (about 0.01 to 10 t / cm), preferably 1 × 10 ⁵ to 1 × 10 ⁷ N / m (about 0.1)
It is about 10 t / cm).

The draw ratio can be selected from a wide range, and for example, the draw ratio is about 1.1 to 10 times, preferably the draw ratio is about 1.3 to 5 times, and more preferably the draw ratio is 1.5.
It may be about 3 times. The roll rolling is performed, for example, by a thickness reduction rate (reduction rate) of about 0.9 to 0.1, preferably about 0.77 to 0.2, and more preferably about 0.67.
It can be performed at about 0.33.

The stretching temperature may be equal to or higher than the melting point or glass transition temperature of the dispersed phase resin. Further, as a resin constituting the continuous phase, a resin having a higher glass transition temperature or melting point than the dispersed phase resin (for example, about 5 to 200 ° C., preferably 5
Uniaxially stretched while melting or softening the disperse phase resin, the disperse phase resin is much more easily deformed than the continuous phase resin, so that the aspect ratio of the disperse phase particles can be increased, A film having particularly large anisotropy of light scattering can be obtained. A preferable stretching temperature is, for example, 100
~ 200 ° C (110-200 ° C), preferably 11
It is about 0 to 180 ° C (130 to 180 ° C). Also,
When the continuous phase resin is a crystalline resin, the rolling temperature is
It may be a temperature below the melting point of the resin and in the vicinity of the melting point, and when the continuous phase resin is an amorphous resin, it may be below the glass transition temperature and in the vicinity of the glass transition temperature.

[0111]

According to the present invention, since the light diffusing film has an ultraviolet absorbing property, the display quality can be stably maintained for a long period in a transmissive display device (transmissive liquid crystal display device, etc.) The components can be effectively protected from the ultraviolet rays leaking from them. Further, in a backlight using a wedge-shaped reflection groove formed in the lower part of the light guide plate without using a white scatterer composed of a fluorescent material, components (for example, a diffusion film, a prism sheet or Brightness enhancement sheet, liquid crystal display cell, etc.) can be effectively protected.

[0112]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples.

The characteristics of the light diffusion films used in Examples and Comparative Examples, and the surface light source device and the transmission type liquid crystal display device using the same were evaluated according to the following methods.

[Ultraviolet absorption characteristic] The ultraviolet absorption characteristic of the diffusion film was measured by SpectrophotometerU manufactured by Hitachi, Ltd.
Measured at -3300. Table 1 shows the transmittance of ultraviolet rays of 365 nm emitted from mercury.

[Light diffusion characteristics] NDH-30 made by NIPPON DENSHOKU
It was measured using 0A. The haze value is shown in Table 1.

[Anisotropy] The scattered light intensity F with respect to the scattering angle θ was measured using the measuring apparatus shown in FIG. The stretching direction of the anisotropic scattering sheet was defined as the X-axis direction, and the direction orthogonal to this direction was defined as the Y-axis direction. As an index of anisotropy, F (18
The values of (°) = Fy (18 °) / Fx (18 °) are shown in Table 1.

[Ultraviolet Irradiation Acceleration Test] An ultraviolet irradiation acceleration test was conducted using "Metal Weather" manufactured by Diepla Wintes. Irradiation was performed at a temperature of 60 ° C. and an output of 75 mW for 10 hours. In this test, a diffusion film and a prism sheet (BEFIII manufactured by 3M Co., Ltd.) were overlaid, and the diffusion sheet was irradiated as an irradiation surface to change the color of both (the degree of yellowing).
The following criteria were visually evaluated. ○: hardly discolored △: slightly yellowed ×: severely yellowed [Measurement of ultraviolet ray leakage from surface light source device] A surface light source device having a wedge-shaped lower part of the light guide plate was prepared, and A film was placed on the emitting surface, and the emission spectrum was measured with PHOTAL7000 manufactured by Otsuka Electronics to examine the degree of leakage of ultraviolet rays. In addition, in this surface light source device, 36 from the light guide plate.
It emits ultraviolet rays of 5 nm. Further, with respect to the emission intensity of the ultraviolet rays of 365 nm in the emission spectrum, the degree of blocking the ultraviolet rays when the film was placed on the light guide plate was evaluated according to the following criteria.

○: 10% or less Δ: more than 10% and less than 30% ×: leaking 30% or more Example 1 Crystalline polypropylene resin PP (F133, manufactured by Grand Polymer Co., Ltd.) as a continuous phase resin Rate 1.50
3) 90 parts by weight, 9 parts by weight of polystyrene resin GPPS (general-purpose polystyrene resin, GPPS # 30 manufactured by Daicel Chemical Industries, Ltd., refractive index 1.589) as a dispersed phase resin, and epoxidized diene as a compatibilizer. -Based block copolymer resin (Epofriend A manufactured by Daicel Chemical Industries, Ltd.)
T202; styrene / butadiene = 70/30 (weight ratio) Epoxy equivalent 750, refractive index about 1.57) 0.5
0.4 parts by weight of a benzotriazole-based ultraviolet absorber (manufactured by Ciba Specialty Chemicals Co., Ltd., “Tinuvin 234”), and an aminotriazine-based light stabilizer (manufactured by Ciba Specialty Chemicals Co., Ltd.), 0.1 parts by weight of "Kimasorp 944FD") was used.

The continuous phase resin, the dispersed phase resin, the ultraviolet absorber and the light stabilizer were dried at 70 ° C. for about 4 hours, kneaded in a Banbury mixer, melted at about 240 ° C. in an extruder, and drawn from a T-die to draw ratio. The film was extruded by about 3 times against a cooling drum having a surface temperature of 25 ° C. to produce a film having a thickness of about 100 μm. When the central portion in the thickness direction of the cross section was observed with a transmission electron microscope (TEM), the dispersed phase was found to have a substantially spherical shape (aspect ratio of about 1.5, average particle diameter of about 5 μm) in the central portion.
m) was dispersed in a rugby ball shape having a small aspect ratio.

Comparative Example 1 A commercially available light-diffusing plate diffusion sheet (“Ruirulight TRX100” manufactured by Reiko Co., Ltd.) was used as a comparative example.

Example 2 Crystalline polypropylene resin PP (F133, manufactured by Grand Polymer Co., Ltd.) as a continuous phase resin, refractive index 1.50
3) 85 parts by weight, and polystyrene-based resin GPPS (general-purpose polystyrene-based resin, GPPS # 30 manufactured by Daicel Chemical Industries, Ltd., refractive index 1.589) as a dispersed phase resin 14
Parts by weight, as the compatibilizer, an epoxidized diene-based block copolymer resin (manufactured by Daicel Chemical Industries, Ltd., Epofriend AT202; styrene / butadiene = 70/30 (weight ratio)) epoxy equivalent 750, refractive index about 1.57 ) 1 part by weight is used as a component for the light diffusion layer, 99.5 parts by weight of the crystalline polypropylene resin PP and a benzotriazole type ultraviolet absorber ("Tinuvin 234" manufactured by Ciba Specialty Chemicals Co., Ltd.) 0 4 parts by weight, and 0.1 part by weight of an aminotriazine-based light stabilizer (Ciba Soap 944FD, manufactured by Ciba Specialty Chemicals Co., Ltd.) were used as components for the transparent resin layer.

The light diffusion layer component and the transparent resin layer component are each dried at 70 ° C. for about 4 hours and kneaded with a Banbury mixer to obtain a light diffusion layer resin composition and a transparent resin layer resin as a surface layer. The composition was melted at about 240 ° C. in a multi-layer extruder and extruded from a T-die at a draw ratio of about 3 times to a cooling drum having a surface temperature of 60 ° C. ) 45 μm was laminated to produce a laminated sheet having a three-layer structure (thickness 150 μm).

Observation of the central light diffusing layer with a transmission electron microscope (TEM) revealed that the dispersed phase in the central layer was substantially spherical (aspect ratio was about 1.4, average particle size was about 6 μm).
m) or a rugby ball shape having a small aspect ratio.

Comparative Example 2 A light diffusion film was prepared in the same manner as in Example 1 without using an ultraviolet absorber. That is, 90 parts by weight of crystalline polypropylene resin PP (F133, manufactured by Grand Polymer Co., Ltd., refractive index 1.503) as the continuous phase resin, and polystyrene resin GPPS (general-purpose polystyrene resin, Daicel Chemical Industries ( Made by G
PPS # 30, refractive index 1.589) 9 parts by weight, and an epoxidized diene-based block copolymer resin as a compatibilizer (manufactured by Daicel Chemical Industries, Ltd. Epofriend AT202; styrene / butadiene = 70/30 (weight) Ratio) Epoxy equivalent of 750, refractive index of about 1.57) 0.5 parts by weight, and aminotriazine light stabilizer [Cimasorp 944FD] 0.5
A light-diffusing film was produced using the parts by weight.

Example 3 Crystalline polypropylene resin PP (F133, manufactured by Grand Polymer Co., Ltd.) as a continuous phase resin, refractive index 1.50
3) 80 parts by weight and an amorphous copolyester resin (PET-G, EASTMAN CHEMI) as a dispersed phase resin
EA Corp. Eastar PETG GN071,
18 parts by weight of refractive index 1.567) and an epoxidized diene block copolymer resin as a compatibilizer (Epofriend AT202 manufactured by Daicel Chemical Industries Ltd .; styrene / butadiene = 70/30 (weight ratio) epoxy equivalent) 750, a refractive index of about 1.57) 1.3 parts by weight, a benzotriazole-based ultraviolet absorber (Ciba Specialty Chemicals Co., Ltd., "Tinuvin 234") 0.2 parts by weight, and an aminotriazine-based photostable. A light diffusing film was prepared in the same manner as in Example 1 using 0.2 parts by weight of the agent (“Cimasoap 944FD” manufactured by Ciba Specialty Chemicals Co., Ltd.).

Comparative Example 3 A commercially available diffusion sheet for a light guide plate (condensing type D121 manufactured by Tsujiden Co., Ltd.) was used as a comparative example.

Example 4 As a component for the light diffusion layer, a crystalline polypropylene resin PP (F manufactured by Grand Polymer Co., Ltd.) as a continuous phase resin
109 BA, refractive index 1.503) 70 parts by weight, amorphous copolyester resin (PET-G) as dispersed phase resin,
Eastman manufactured by Eastman Chemical Co., Ltd.
r PETG GN071, 28 parts by weight of refractive index 1.567, epoxidized diene block copolymer resin as compatibilizer (Epofriend AT202 manufactured by Daicel Chemical Industries, Ltd .; styrene / butadiene = 70/30 (weight) Ratio) 2 parts by weight of an epoxy equivalent of 750 and a refractive index of about 1.57) were used.

As a component for the transparent resin layer, a polypropylene-based copolymer resin (manufactured by Nippon Polychem Co., Ltd., “FX-
3 ") and 99.3 parts by weight, and 0.7 parts by weight of a benzotriazole-based ultraviolet absorber (" Tinuvin 234 "manufactured by Ciba Specialty Chemicals).

The light diffusion layer component and the transparent resin layer component are each dried at 70 ° C. for about 4 hours and kneaded with a Banbury mixer to obtain a light diffusion layer resin composition and a transparent resin for forming a surface layer. The resin composition for layers is prepared, melted at about 240 ° C. in an extruder for multilayer, and drawn from the T die at a draw ratio of about 3 times,
It was extruded to a cooling drum having a surface temperature of 25 ° C. to prepare a three-layer laminated sheet (thickness 300 μm) in which a surface layer (transparent resin layer) 75 μm was laminated on both sides of a light diffusion layer 150 μm. When the central layer was observed with a transmission electron microscope (TEM), the dispersed phase was dispersed in the central layer in a substantially spherical shape.

This sheet was roll-rolled (125 ° C., rolling ratio doubled (thickness reduction ratio approximately 1/2), width reduction ratio about 3).
%) To obtain a film having a thickness of 150 μm. When the film was observed by TEM (staining with osmic acid), the dispersed phase of the light diffusion layer (1) was a very long and narrow fibrous substance with an average major axis length of about 30 μm and an average minor axis length of about 1.5 μm. Had the shape of.

[0131]

[Table 1]

[0132]

[Table 2]

[Brief description of drawings]

FIG. 1 is a schematic exploded perspective view showing an example of a surface light source device and a transmissive liquid crystal display device of the present invention.

FIG. 2 is a schematic view for explaining another example of the surface light source unit including the light diffusion film.

FIG. 3 is a schematic cross-sectional view showing another example of the light diffusion film.

FIG. 4 is a conceptual diagram for explaining anisotropic scattering of a light diffusion film.

FIG. 5 is a schematic sectional view for explaining a method for measuring light scattering characteristics.

FIG. 6 is a schematic cross-sectional view showing a conventional transmissive liquid crystal display device.

FIG. 7 is a schematic cross-sectional view showing a backlight unit of a transmissive liquid crystal display device.

[Explanation of symbols]

1 ... Display device 2 ... Liquid crystal display unit 3 ... Surface light source unit 4 ... Tube light source 5 ... Light guide member 6a ... Reflective member or reflective layer 7, 17, 27, 37 ... Ultraviolet absorbing light diffusion film 8 ... Prism sheet 15 ... Light guide plate 17a, 27a, 37a ... Continuous phase 17b, 27b, 37b ... Dispersed phase 18 ... Wedge-shaped reflective groove 29 ... Transparent resin layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // F21Y 103: 00 F21Y 103: 00 (72) Inventor Tomohiro Sasakawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Inventor Naoko Iwasaki 2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Inventor Akemi Yuki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Ryoden Co., Ltd. (72) Inventor Osamu Murakami 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Denki Co., Ltd. F-term (reference) 2H042 AA03 AA26 BA03 BA12 BA20 2H091 FA14Z FA21Z FA23Z FA32Z FA43Z FB02 FB12 FD06 FD15 LA03

Claims (6)

[Claims] 1. A side portion is disposed in proximity to a light source,
And a light guide plate for guiding the light from the light source, a wedge-shaped reflection groove formed under the light guide plate for reflecting the light guided by the light guide plate to the light emitting surface side, and the light guide plate. A surface light source device including a surface light source unit composed of an ultraviolet absorbing light diffusing film disposed on the light emitting surface side of the. 2. A light diffusing layer (1) in which an ultraviolet absorbing light diffusing film is composed of a plurality of resins having different refractive indexes.
And a transparent resin layer (2) laminated on at least one surface of the light diffusion layer, wherein at least the transparent resin layer (2) contains an ultraviolet absorber. 3. The surface light source device according to claim 1, wherein the ultraviolet absorbing light diffusing film has light scattering anisotropy. 4. The ultraviolet absorbing light diffusing film has a scattering characteristic F (θ) showing a relationship between a scattering angle θ and a scattered light intensity F, wherein the scattering characteristic in the X-axis direction of the film is Fx (θ), Y.
When the scattering characteristic in the axial direction is Fy (θ), the scattering angle θ =
Fy (θ) / Fx (θ)> 1.0 in the range of 4 to 30 °
3. The surface light source device according to claim 1, which has a scattered light intensity characteristic that satisfies 1. 5. A transmissive liquid crystal display device comprising the surface light source device according to claim 1. 6. When the horizontal direction of the liquid crystal display surface is the X axis, the Y axis of the ultraviolet absorbing light diffusing film according to claim 4 is arranged along the X axis of the liquid crystal display surface. Transmissive liquid crystal display device.