WO2023080130A1 - Film de diffusion de lumière anisotrope, film de diffusion de lumière anisotrope avec couche adhésive, et dispositif d'affichage d'image - Google Patents

Film de diffusion de lumière anisotrope, film de diffusion de lumière anisotrope avec couche adhésive, et dispositif d'affichage d'image Download PDF

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WO2023080130A1
WO2023080130A1 PCT/JP2022/040850 JP2022040850W WO2023080130A1 WO 2023080130 A1 WO2023080130 A1 WO 2023080130A1 JP 2022040850 W JP2022040850 W JP 2022040850W WO 2023080130 A1 WO2023080130 A1 WO 2023080130A1
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layer
resin
anisotropic light
light diffusion
ratio
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PCT/JP2022/040850
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English (en)
Japanese (ja)
Inventor
知彰 原田
隆敏 牟田
博樹 中村
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三菱ケミカル株式会社
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Priority claimed from JP2021179414A external-priority patent/JP2023068370A/ja
Priority claimed from JP2021212116A external-priority patent/JP2023096394A/ja
Priority claimed from JP2021212117A external-priority patent/JP2023096395A/ja
Application filed by 三菱ケミカル株式会社 filed Critical 三菱ケミカル株式会社
Publication of WO2023080130A1 publication Critical patent/WO2023080130A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L69/00—Compositions of polycarbonates; Compositions of derivatives of polycarbonates
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/54—Accessories
    • G03B21/56—Projection screens
    • G03B21/60—Projection screens characterised by the nature of the surface
    • G03B21/62—Translucent screens
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements

Definitions

  • the present invention relates to an anisotropic light diffusion film.
  • This application is based on Japanese Patent Application No. 2021-179414 filed in Japan on November 2, 2021, Japanese Patent Application No. 2021-212116 filed in Japan on December 27, 2021, and Japan on December 27, 2021. Claiming priority based on Japanese Patent Application No. 2021-212117 filed, March 18, 2022, Japanese Patent Application No. 2022-043572, Japanese Patent Application No. 2022-043573, and Japanese Patent Application No. 2022-043574. , the contents of which are hereby incorporated by reference.
  • a light diffusion film is used as an optical film used in a liquid crystal display.
  • a light diffusion film is used as a diffuser plate in a liquid crystal display device to obtain a uniform planar light source by planarly scattering the light from the light source. It is used as a screen for
  • a light diffusion film As a light diffusion film, one or both surfaces of the film are roughened, or the surface of the film is provided with a scattering particle-containing layer obtained by coating transparent organic fine particles such as acrylic resin. It is used.
  • a scattering particle-containing layer obtained by coating transparent organic fine particles such as acrylic resin.
  • an internal structure containing a diffusion element of organic particles inside a matrix resin A light diffusion film is disclosed in which a light diffusion layer is formed on at least one surface of the diffusion film, and the light diffusion layer is composed of at least a binder resin and particles.
  • an anisotropic light diffusion film that scatters light in a specific direction instead of scattering light evenly has been desired.
  • Applications of such an anisotropic light diffusion film include the display surface of large-sized liquid crystal televisions, diffusion plates, screens of projection type image display devices such as rear projection televisions, and the like.
  • Patent Document 2 as an anisotropic scattering film suitable as a screen of a projection type image display device and excellent in all performances of resolution, contrast, and brightness, at least two or more incompatible resins wherein the phase-separated structure of the immiscible resin is a sea-island structure comprising a sea phase comprising at least one resin and an island phase comprising at least one resin, wherein the island phase comprises
  • the film has a rod-like shape oriented in one direction at least on the surface layer, and is characterized in that the scattered light intensity is different between the scattering plane parallel to the orientation direction of the island phase and the scattering plane perpendicular to the orientation direction of the island phase.
  • Patent Document 3 describes an anisotropic optical film that suppresses glare and abrupt changes in luminance and has an optimized balance of optical properties including light diffusion properties.
  • a film is disclosed.
  • the mainstream is the direct type, in which the light source is arranged on the back of the liquid crystal panel, or the edge-light type, in which the light source is arranged near the side of the liquid crystal panel.
  • Backlight units used in large-sized liquid crystal displays are mainly direct type cold cathode ray tube backlight units that use cold cathode ray tubes as the light source from the viewpoint of excellent brightness of the screen and uniformity of brightness within the screen. Used.
  • a cold cathode ray tube which is a linear light source
  • a plurality of cold cathode ray tubes may be arranged in parallel in order to brighten the display screen. In this case, light from adjacent cold cathode ray tubes interferes with each other, and stripe-like spots of brightness tend to occur.
  • edge-light type backlight units have also come to be used in large liquid crystal displays.
  • an edge light type LED backlight unit using light emitting diodes (LEDs) as a light source is often used. Parts such as a light plate are required.
  • LEDs light emitting diodes
  • direct backlight units using LEDs as light sources have come to be used for reasons such as reducing power consumption and reducing costs by omitting the light guide plate.
  • Such a direct type LED backlight unit generally has an aspect in which the LED light sources are arranged substantially on the same plane as the reflector.
  • luminance spots such as darkening of the corresponding portions between the LEDs, tend to occur in the display device.
  • an anisotropic diffusion film capable of diffusing light in a specific direction can prevent light from scattering in directions other than the direction in which the viewer views the screen. You can expect to be able to solve these problems.
  • an object of one aspect of the present invention is to provide a light diffusion film that is excellent in brightness and visibility when mounted on a display.
  • Another object of the present invention is to provide an anisotropic light diffusion film having both an anisotropic light diffusion property for diffusing light in a specific direction and low reflectivity.
  • an anisotropic light diffusion film that can diffuse light in a specific direction can prevent light from scattering in directions other than the direction in which the viewer views the screen, enabling viewing at a wide viewing angle. I thought it would be possible to improve the brightness reflected in the human eye. On the other hand, we discovered that if the anisotropic light diffusion is too high, the visibility of the screen when viewed from the front deteriorates. It was found that the brightness and visibility were improved when mounted. Further, as a result of intensive studies by the present inventors, in an anisotropic light diffusion film having a sea-island structure, the anisotropic light diffusion property and the It has been found that both low reflectivity can be achieved.
  • the gist of the present invention is as follows.
  • a light diffusion film having at least a first layer capable of scattering incident light in the direction of travel of the light An anisotropic light-diffusing film having a ratio of 60° brightness ratio to front brightness ratio (60° brightness ratio/front brightness ratio) determined by the following method of 0.30 or more and 0.60 or less.
  • ⁇ 60° luminance ratio> In the light diffusion film, the ratio (C/B) of the luminance C in the direction inclined 60° from the normal N direction of the film surface to the light diffusion direction and the front luminance B in the normal N direction of the film surface is 60° Let it be the luminance ratio.
  • ⁇ Front luminance ratio> The ratio (B/A) of the front luminance B of the light diffusion film and the front luminance A in the normal N direction of the film surface in the blank sample satisfying the following conditions (1) and (2) is defined as the front luminance ratio. do.
  • the ratio of the luminous reflectance R SCE of the specular component exclude method to the luminous reflectance R SCI of the specular component include method (R SCE /R SCI ) is 50% or more, the anisotropic light-diffusing film according to any one of the above [1] to [7].
  • the diol component having an alicyclic structure is one or more selected from spiroglycol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. , the anisotropic light diffusion film according to [19] above.
  • the first layer comprises an amorphous polyester resin and a polycarbonate resin (excluding a polycarbonate resin containing a structural unit (a) derived from a dihydroxy compound represented by the following general formula (1)).
  • It has a first layer having a sea-island structure with a continuous phase (I) and a dispersed phase (II), has a haze of 40% or more as measured in accordance with JIS K7136, and is tensile in the MD and TD directions.
  • An anisotropic light-diffusing film having an intensity ratio ( ⁇ MD / ⁇ TD ) of 0.75 to 1.25.
  • It has a first layer having a sea-island structure composed of a continuous phase (I) and a dispersed phase (II), has a haze of 40% or more as measured according to JIS K7136, and has a tensile strength ⁇ MD in the MD direction.
  • a first layer having a sea-island structure composed of a continuous phase (I) and a dispersed phase (II) is provided, and the volume of the dispersed phase at the central portion in the thickness direction of the first layer is 20 ⁇ m 3 or more and 120 ⁇ m 3 or less.
  • the ratio of the average dispersion diameter in the MD direction to the average dispersion diameter in the TD direction of the dispersed phase (II) is 3 or more at the center in the thickness direction. .
  • an anisotropic light diffusion film wherein the area of the dispersion diameter in the TD cross section at the central portion in the thickness direction of the dispersed phase (II) is 2 ⁇ m 2 or more.
  • It has a sea-island structure with a continuous phase (I) and a dispersed phase (II), and at least one of the continuous phase (I) and the dispersed phase (II) contains a thermoplastic resin having an average refractive index of 1.53 or less.
  • An anisotropic light diffusing film including.
  • An anisotropic light-diffusing film with an adhesive layer comprising an adhesive layer on at least one surface of the anisotropic light-diffusing film of any one of [1] to [31] above.
  • An image display device comprising the anisotropic light diffusion film according to any one of [1] to [31] above.
  • the image display device according to [34] having a screen size of 32 inches or more.
  • the anisotropic light-diffusing film according to one aspect of the present invention is excellent in anisotropic light-diffusing properties, transmittance, and low reflectivity, and is therefore excellent in brightness and visibility when mounted on a display.
  • An anisotropic light-diffusing film according to another aspect of the present invention can have both anisotropic light-diffusing properties and low reflectivity.
  • FIG. 4 is a cross-sectional view (MD cross section) of an anisotropic light diffusion film of Test Example 4-1.
  • FIG. 4 is a cross-sectional view (TD cross section) of an anisotropic light diffusion film of Test Example 4-1.
  • FIG. 10 is a cross-sectional view (MD cross section) of an anisotropic light-diffusing film of Test Example 4-2.
  • FIG. 10 is a cross-sectional view (TD cross section) of an anisotropic light-diffusing film of Test Example 4-2.
  • FIG. 10 is a cross-sectional view (MD cross section) of an anisotropic light-diffusing film of Test Example 4-3.
  • FIG. 10 is a cross-sectional view (TD cross section) of an anisotropic light-diffusing film of Test Example 4-3.
  • FIG. 10 is a cross-sectional view (MD cross section) of an anisotropic light-diffusing film of Test Example 4-4.
  • FIG. 10 is a cross-sectional view (TD cross section) of an anisotropic light-diffusing film of Test Example 4-4.
  • FIG. 10 is a cross-sectional view (MD cross section) of an anisotropic light-diffusing film of Test Example 4-7.
  • FIG. 10 is a cross-sectional view (TD cross section) of an anisotropic light-diffusing film of Test Example 4-7.
  • FIG. 10 is a cross-sectional view (MD cross section) of an anisotropic light-diffusing film of Test Example 4-8.
  • FIG. 10 is a cross-sectional view (TD cross section) of an anisotropic light-diffusing film of Test Example 4-8.
  • An anisotropic light diffusion film (hereinafter also referred to as “this light diffusion film”) according to one embodiment of the present invention includes a first layer (hereinafter simply referred to as “first (also referred to as “layer”).
  • first also referred to as “layer”
  • “capable of scattering incident light in the traveling direction of light” means that the front luminance ratio is 70% or more and the 60-degree luminance ratio is 20% or more.
  • the ratio of the 60° luminance ratio (60° luminance ratio/front luminance ratio) to the front luminance ratio obtained by the following method is 0.30 or more and 0.30. It is preferably 60 or less.
  • the 60° luminance ratio/front luminance ratio is more preferably 0.32 or more, still more preferably 0.34 or more, and even more preferably 0.36 or more. It is more preferably 0.55 or less, more preferably 0.50 or less, more preferably 0.48 or less, still more preferably 0.46 or less, and even more preferably 0.44 or less.
  • the fact that the 60° luminance ratio/front luminance ratio is within the above range means that the display has good brightness and visibility both when viewed from the front and when viewed at a wide viewing angle. Therefore, when the 60° luminance ratio/front luminance ratio is within the above range, it can be said that the anisotropic light diffusibility and the front luminance are well balanced.
  • the 60° luminance ratio and the front luminance ratio are obtained by the following methods.
  • the ratio (C/B) of the luminance C in the direction inclined 60° from the normal N direction of the film surface to the front luminance B in the normal N direction of the film surface (100%) is the 60° luminance ratio (%).
  • An example of the measuring method is shown in FIG.
  • the light diffusion film 1 is fixed to the backlight unit 2, and light is made to enter from the normal N direction of the film surface (thick arrow in FIG. 1).
  • the luminance C is the measured value when the backlight unit 2 is tilted so that the luminance meter 3 is positioned in a direction tilted 60° from the normal N direction of the film surface to the light diffusion direction y.
  • the luminance B is the measured value when the backlight unit 2 is arranged so that the luminance meter 3 is positioned in the normal N direction.
  • front luminance ratio The ratio (B/A) of the front luminance B of this light diffusion film to the front luminance A in the normal N direction of the film surface (100%) in a blank sample that satisfies the following conditions (1) and (2). Brightness ratio (%).
  • [Blank sample] (1) The total light transmittance measured according to JIS K7361-1 is 90% or more. (2) The haze measured according to JIS K7136 is 1% or less.
  • the front luminance A is obtained when the blank sample is fixed to the backlight unit, light is incident from the normal N direction of the film surface, and the backlight unit is arranged so that the luminance meter is positioned in the normal N direction. is the measured value.
  • the 60° brightness ratio of the present light diffusion film is preferably 27% or more, more preferably 30% or more, and even more preferably 32% or more.
  • the upper limit of the 60° luminance ratio is not particularly limited, it is preferably 99% or less, more preferably 95% or less.
  • the anisotropic light diffusing property of the film is good, and it is possible to prevent light from scattering in a direction other than the direction in which the viewer views the screen. can improve the brightness seen by viewers.
  • the front luminance ratio of the present light diffusion film is preferably 50% or more, more preferably 60% or more, further preferably 70% or more, and 80% or more. is even more preferred.
  • the upper limit of the front luminance ratio is not particularly limited, but is preferably 99% or less, more preferably 95% or less, and even more preferably 90% or less.
  • the haze of the present light diffusion film is preferably 10% or more, more preferably 20% or more, still more preferably 25% or more, and even more preferably 30% or more. Furthermore, among them, 40% or more is preferable, 45% or more is more preferable, 50% or more is still more preferable, 60% or more is still more preferable, and 70% or more is particularly preferable. On the other hand, the upper limit of the haze is not particularly limited, but is preferably 99% or less, more preferably 95% or less, and even more preferably 90% or less.
  • the present light diffusion film has a structure containing a liquid crystal component, organic fine particles, an anisotropic inorganic filler, or a dispersed phase in a sea-island structure (hereinafter also referred to as a "dispersed component")
  • a large amount of the dispersed component is present in the film.
  • haze tends to increase. Therefore, when the haze is within the above range, the anisotropic light diffusibility of the film tends to be high.
  • the haze in the present invention can be measured according to JIS K7136 by the method described in Examples.
  • the light diffusion film preferably has a total light transmittance of 85% or more, more preferably 86% or more, even more preferably 87% or more, and 90% or more. is even more preferable, and 92% or more is particularly preferable. Furthermore, among them, it is preferably 94% or more, more preferably 94.5% or more, still more preferably 95% or more, and even more preferably 96% or more. On the other hand, although the upper limit of the total light transmittance is not particularly limited, it is preferably 99% or less.
  • the total light transmittance in the present invention can be measured according to JIS K7361-1 by the method described in Examples.
  • the present light diffusion film has a reflectance of Specular Component Include method measured using a spectrophotometer, that is, a luminous reflectance R SCI of 32 or less. It is preferably 29 or less, even more preferably 26 or less, and even more preferably 22 or less. Furthermore, among them, it is preferably 20 or less, more preferably 18 or less, still more preferably 16 or less, and even more preferably 14 or less.
  • the lower limit of the luminous reflectance R SCI is not particularly limited, but from the viewpoint of anisotropic light diffusion, it is preferably 5 or more, more preferably 5.5 or more. When the luminous reflectance R SCI is within the above range, the film tends to have low reflectivity.
  • This light diffusion film has a specular component exclude method (Specular Component Exclude method) reflectance measured using a spectrophotometer (100%) with respect to the luminous reflectance R SCI , that is, the luminous reflectance R
  • the SCE ratio (R SCE /R SCI ) is preferably 40% or more, more preferably 45% or more, still more preferably 50% or more, and even more preferably 55% or more. , above 60%.
  • the upper limit of the ratio (R SCE /R SCI ) is not particularly limited as long as it is 100% or less. When the ratio (R SCE /R SCI ) is within the above range, the film has good light diffusing properties.
  • the luminous reflectance R SCI and the luminous reflectance R SCE in the present invention can be measured by the method described in Examples using a black background having a luminous reflectance R SCI of 5.1.
  • the light diffusion film has a heat dimensional change rate in the MD direction measured under test conditions of 110°C for 60 minutes in accordance with JIS K7133: 1999, which is 0.5% or less. is preferred, 0.4% or less is more preferred, and 0.3% or less is even more preferred.
  • the thermal dimensional change rate is within the above range, it can be considered that the present light diffusion film has sufficient heat resistance at 110° C. or less.
  • Such a film can be suitably used as a constituent member of an image display device mounted on a vehicle.
  • the surface hardness of the light diffusion film is measured on the surface of the film layer in accordance with JIS K5600 under the conditions of a temperature of 23°C ⁇ 2°C, a relative humidity of 50% ⁇ 10°C, and a load of 750 gf. is preferably B or higher, more preferably HB or higher, and even more preferably F or higher. When the surface hardness is within the above range, the present light diffusion film can be prevented from being scratched.
  • the light diffusion film preferably has an arithmetic mean height Ra of 10 ⁇ m or less, more preferably 5 ⁇ m or less, even more preferably 3 ⁇ m or less, and preferably 1 ⁇ m or less. Even more preferable.
  • the lower limit of the arithmetic mean roughness Ra is not particularly limited. More preferred.
  • the arithmetic mean height Ra in the present invention can be measured according to JIS B0601:2001 by the method described in Examples.
  • the tensile strength ratio ( ⁇ MD / ⁇ TD ) in the MD direction and the TD direction is preferably 0.75 to 1.25, especially It is more preferably 0.80 or more and 1.20 or less, more preferably 0.85 or more and 1.15 or less, and more preferably 0.90 or more and 1.10 or less. preferable.
  • the anisotropy of the tensile strength is small.
  • the "MD direction” indicates the take-up (flow) direction of the sheet or film when manufacturing the sheet or film
  • the "TD direction” indicates the orthogonal direction.
  • both the tensile strength ⁇ MD in the MD direction and the tensile strength ⁇ TD in the TD direction are preferably 50 MPa or more, more preferably 55 MPa or more, and 60 MPa or more. is more preferable.
  • the upper limit of the tensile strength is not particularly limited, it is preferably 200 MPa or less.
  • the tensile strength ⁇ MD in the MD direction and the tensile strength ⁇ TD in the TD direction are within the above ranges, reflection due to interfacial peeling between the matrix component and the dispersed component is less likely to occur, and the film tends to have low reflectivity. , the total light transmittance tends to be high.
  • the tensile strength of the light diffusion film can be measured according to JIS K7161-1 by the method described in Examples.
  • the first layer will be described below.
  • the first layer has a structure capable of scattering incident light in the traveling direction of the light.
  • a liquid crystal component, organic fine particles, anisotropic inorganic filler, or other dispersing component is added to the matrix resin
  • a liquid crystal component, organic fine particles, anisotropic inorganic filler, or other dispersing component is added to the matrix resin
  • Patent Document 1 JP-A-2010-079197, International Publication No. 2015/182517, etc.
  • those having an uneven structure on the film surface for example, JP-A-2013-114846, etc.
  • a light diffusion film having an uneven structure on its surface can have a 60° luminance ratio/front luminance ratio within the above range by adjusting the uneven structure.
  • such a light diffusion film may cause a striped pattern called moire when mounted on a display, and it may be difficult to increase the production speed due to the manufacturing method.
  • a light diffusion film having a sea-island structure with a continuous phase (I) and a dispersed phase (II) has a 60° luminance ratio by adjusting the components and amounts of the continuous phase (I) and the dispersed phase (II). /front luminance ratio can be set within the above range.
  • the first layer preferably has an uneven structure on the surface or has a sea-island structure with the continuous phase (I) and the dispersed phase (II), and the continuous phase (I) and the dispersed phase (II) It is more preferable to have a sea-island structure by Preferred forms of the first layer are described below.
  • a first layer according to a first preferred embodiment of the present invention has an uneven structure on its surface.
  • the concave-convex structure of the first layer is not particularly limited as long as the 60° luminance ratio/front luminance ratio of the present light diffusion film is within the above range.
  • Examples of the first layer having an uneven structure on its surface include the following. (1) Concavities and convexities are formed on the surface of a mold base material made of metal, resin, etc., and the shape is transferred from this mold to a resin film, etc.
  • a first layer according to a second preferred embodiment of the present invention has a sea-island structure with a continuous phase (I) and a dispersed phase (II).
  • the continuous phase (I) is the phase that forms the sea in the island-sea structure
  • the dispersed phase (II) is the phase that forms the islands in the island-sea structure.
  • the dispersed structure can be observed with a transmission electron microscope (TEM) or a scanning electron microscope (SEM).
  • the first layer has a dispersed structure in which the island portions of the sea-island structure, ie, the dispersed phase (II), are extended in the MD direction, and the sea portion, ie, the continuous phase (I) is dispersed. preferable.
  • the anisotropic light diffusibility of the film is enhanced.
  • At least one of the continuous phase (I) and the dispersed phase (II) of the first layer preferably contains a thermoplastic resin having an average refractive index of 1.53 or less.
  • the average refractive index of the thermoplastic resin is more preferably 1.52 or less, even more preferably 1.51 or less.
  • the lower limit of the average refractive index is not particularly limited, it is preferably 1.45 or more.
  • thermoplastic resin having an average refractive index of 1.53 or less is preferably a resin component that constitutes the continuous phase (I). Among them, it is preferable that the thermoplastic resin having an average refractive index of 1.53 or less accounts for 50% by mass or more of the resin components constituting the continuous phase (I). Among them, it accounts for 80% by mass or more, more preferably 90% by mass or more (including 100% by mass).
  • the refractive index difference between the continuous phase (I) and the dispersed phase (II) is preferably 0.010 to 0.080, more preferably 0.015 or more or 0.075 or less, and more preferably 0.020 or more or 0.070 or less is more preferable.
  • the refractive index difference between the continuous phase (I) and the dispersed phase (II) is within the above range, the internal reflection of the film is suppressed and the reflectivity tends to be low.
  • the anisotropic light diffusibility can be enhanced while maintaining a high total light transmittance.
  • the refractive index difference between the continuous phase (I) and the dispersed phase (II) is calculated as the absolute value of the refractive index difference between the raw material resins forming the continuous phase (I) and the dispersed phase (II).
  • the refractive index of each phase can be determined from the compounding ratio of the raw material resins and the average refractive index of each resin. shall be calculated.
  • the continuous phase (I) and dispersed phase (II) in the first layer can be formed by using at least two thermoplastic resins.
  • the thermoplastic resin include polyester resins such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate and polybutylene terephthalate; polyolefins such as polyethylene, polypropylene, cyclopolyolefin and polymethylpentene; acetylcellulose and nitrocellulose.
  • Cellulose derivatives such as , acetylbutyl cellulose, ethyl cellulose, methyl cellulose; vinyl resins such as vinyl acetate and its copolymers, vinyl chloride and its copolymers, vinylidene chloride and its copolymers; acetals such as polyvinyl formal and polyvinyl butyral Acrylic resins such as acrylic resins such as polyacrylates and copolymers thereof, methacrylic resins such as polymethacrylates and copolymers thereof; acrylic resins such as polystyrene resins; polyamide resins; be able to.
  • vinyl resins such as vinyl acetate and its copolymers, vinyl chloride and its copolymers, vinylidene chloride and its copolymers
  • acetals such as polyvinyl formal and polyvinyl butyral Acrylic resins such as acrylic resins such as polyacrylates and copolymers thereof, methacrylic resins such as polymethacrylates and copolymers
  • thermoplastic resins are a thermoplastic resin having an average refractive index of 1.53 or less (also referred to as “resin ⁇ "). More specifically, the at least two thermoplastic resins include a combination of resin ⁇ and a thermoplastic resin incompatible therewith (also referred to as “resin ⁇ ”).
  • the term "incompatible” means a state in which at least two resin components are not completely mixed, and may be partially mixed. (TEM) or scanning electron microscope (SEM), micro-phase separation structure due to sea-island structure is observed.
  • the continuous phase (I) and the dispersed phase (II) By forming the continuous phase (I) and the dispersed phase (II) with materials containing these two types of resins ⁇ and ⁇ , the vicinity of the direction inclined 60° from the normal N direction of the surface of the light diffusion film to the light diffusion direction An ideal island component having strong diffusivity can be formed, and an optimum dispersion structure can be formed to exhibit excellent anisotropic light diffusibility.
  • the first layer may contain a resin ⁇ as a third component in addition to the resins ⁇ and ⁇ .
  • the resin ⁇ is a thermoplastic resin incompatible with the resin ⁇ , and preferably forms the dispersed phase (II) together with the resin ⁇ and is compatible with or phase-separated from the resin ⁇ in the dispersed phase (II).
  • the anisotropic light diffusibility of the present light diffusion film can be adjusted.
  • resin ⁇ having an average refractive index of 1.53 or less include polymethyl methacrylate, polypropylene, polyurethane, and the like. From the viewpoint of above, a polycarbonate resin containing a structural unit (a) derived from a dihydroxy compound represented by general formula (1) is preferred.
  • the polycarbonate resin containing the structural unit (a) is preferably the main component in the continuous phase (I) of the first layer.
  • the "main component” means the resin with the highest content among the resins constituting the continuous phase (I) or the dispersed phase (II), for example, the continuous phase (I) or the dispersed phase (II ), a resin component that accounts for 50% by mass or more, particularly 70% by mass or more, especially 80% by mass or more (including 100% by mass).
  • dihydroxy compound represented by the general formula (1) examples include isosorbide, isomannide and isoide, which are stereoisomers. These may be used individually by 1 type, and may be used in combination of 2 or more type. Since these dihydroxy compounds do not have a phenolic hydroxyl group, they are usually produced by transesterification using diester carbonate.
  • isosorbide which is obtained by dehydration condensation of sorbitol produced from various easily available starches, which exists abundantly as a plant-derived resource, has transparency, stretchability, heat resistance and It is most preferable from the aspect of anisotropic light diffusion.
  • the structural unit (a) in the polycarbonate resin accounts for preferably 35 mol% or more, more preferably 40 mol% or more, and even more preferably 45 mol% or more of all structural units derived from the dihydroxy compound. Also, it is preferably 90 mol % or less, more preferably 85 mol % or less, and still more preferably 80 mol % or less. If the ratio of the structural unit (a) is at least the above lower limit, it becomes easy to increase the molecular weight of the polycarbonate resin. On the other hand, if the said ratio is below the said upper limit, polycarbonate resin will be hard to color.
  • the polycarbonate resin containing the structural unit (a) may further contain a structural unit (b) derived from a dihydroxy compound other than the structural unit (a).
  • Examples of the structural unit (b) include a structural unit (b1) derived from an aliphatic dihydroxy compound and/or a structural unit (b2) derived from an alicyclic dihydroxy compound.
  • Specific examples of the aliphatic dihydroxy compound and the alicyclic dihydroxy compound include the following.
  • aliphatic dihydroxy compound examples include 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-ethyl -1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, hydrogenated dilinoleyl glycol, hydrogenated dioleyl glycol, etc. are mentioned. These aliphatic dihydroxy compounds may be used singly or in combination of two or more.
  • the molar ratio between the structural unit (a) and the structural unit (b1) derived from the aliphatic dihydroxy compound can be selected at any ratio. Flexibility and moldability can be improved by adjusting the molar ratio. Therefore, from such a viewpoint, the molar ratio of the structural unit (a) and the structural unit (b1) derived from the aliphatic dihydroxy compound is preferably 35:65 to 99:1, and 40:60 to More preferably 90:10, even more preferably 45:55 to 80:20.
  • Alicyclic dihydroxy compounds include compounds containing a 5- or 6-membered ring structure. When the alicyclic dihydroxy compound has a 5-membered ring structure or a 6-membered ring structure, there are advantages such as improved heat resistance.
  • the six-membered ring structure may be fixed in a chair or boat shape by a covalent bond.
  • the number of carbon atoms contained in the alicyclic dihydroxy compound is usually 70 or less, preferably 50 or less, more preferably 30 or less.
  • An alicyclic dihydroxy compound having 70 or less carbon atoms is preferred because it is easy to synthesize and purify, and is inexpensive and readily available.
  • alicyclic dihydroxy compound containing a 5-membered ring structure or 6-membered ring structure include alicyclic dihydroxy compounds represented by the following general formula (2) or (3).
  • HO—R 10 —OH (3) (In general formulas (2) and (3), R 9 and R 10 each independently represent a substituted or unsubstituted divalent group containing a cycloalkyl structure having 4 to 20 carbon atoms.)
  • Examples of the alicyclic dihydroxy compound represented by the general formula (2) include cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, decalindimethanol, tricyclotetradecanedimethanol, norbornanedimethanol, and adamantanediethanol. Methanol etc. are mentioned.
  • the alicyclic dihydroxy compounds represented by the general formula (3) include tricyclodecanediol, pentacyclopentadecanediol, decalindiol, tricyclotetradecanediol, norbornanediol, and adamantanediol.
  • alicyclic dihydroxy compounds may be used singly or in combination of two or more.
  • the structural unit (b3) is any one or more selected from cyclohexanedimethanol, tricyclodecanedimethanol, adamantanediol and pentacyclopentadecanedimethanol from the viewpoint of availability and ease of handling. Structural units derived from compounds are particularly preferred.
  • the molar ratio of the structural unit (a) and the structural unit (b2) derived from the alicyclic dihydroxy compound is preferably 35:65 to 99:1, more preferably 40:60 to 90:10. More preferably, it is 45:55 to 80:20. When the molar ratio is within the above range, the polycarbonate resin is less likely to be colored and the molecular weight can be easily increased.
  • the glass transition temperature (Tg) of resin ⁇ is preferably 90° C. or higher, more preferably 100° C. or higher, and more preferably 110° C. or higher.
  • the temperature is preferably 350° C. or lower, more preferably 300° C. or lower, and more preferably 250° C. or lower.
  • the glass transition temperature of the resin is determined according to JIS K7121:2012 using a differential scanning calorimeter (for example, "DSC8500" manufactured by PerkinElmer Japan Co., Ltd.) with a temperature range of 0 to 200 ° C. and a heating rate of A value measured at 10°C/min.
  • the apparent viscosity ⁇ 240, ⁇ of the resin ⁇ at 240° C. and a shear rate of 100 (1/s) is preferably 100 (Pa s) to 10000 (Pa s), especially 200 (Pa s) from the viewpoint of moldability. (Pa ⁇ s) or more and 5000 (Pa ⁇ s) or less is more preferable, and among them, 300 (Pa ⁇ s) or more and 1000 (Pa ⁇ s) or less is more preferable.
  • the content of resin ⁇ in the first layer is preferably 10 to 90% by mass, more preferably 20% by mass or more or 80% by mass or less, and more preferably 30% by mass or more or 70% by mass or less. Among them, 40% by mass or more or 65% by mass or less is more preferable.
  • the content of the resin ⁇ is within the above range, the dispersed phase (II) is appropriately formed in the first layer, and the anisotropic light diffusibility is improved.
  • the resin ⁇ examples include at least one resin selected from the group consisting of amorphous polyester resins and amorphous styrene resins.
  • the resin ⁇ is preferably the main component in the dispersed phase (II) of the first layer.
  • amorphous polyester resin for example, a polyalkylene terephthalate resin such as polyethylene terephthalate or a polyalkylene-2,6-naphthalate resin such as polyethylene-2,6-naphthalate is acid-modified and/or diol-modified.
  • a crystalline copolyester may be mentioned.
  • an amorphous polyester resin modified with a diol component having an alicyclic structure that is, an amorphous polyester resin containing a diol component having an alicyclic structure is preferred.
  • amorphous means having no melting peak in DSC measurement.
  • a diol component having at least one alicyclic structure selected from spiroglycol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol Amorphous polyester resins containing are particularly preferred.
  • the amorphous polyester resin containing a diol component having an alicyclic structure various commercially available raw materials can be preferably used.
  • amorphous styrene resin examples include styrene resin, acrylonitrile/styrene copolymer (AS resin), and acrylonitrile/butadiene/styrene copolymer (ABS resin).
  • the average refractive index of the resin ⁇ is preferably 1.53 or higher, more preferably 1.54 or higher, and even more preferably 1.55 or higher, from the viewpoint of anisotropic light diffusion and low reflectivity. On the other hand, from the viewpoint of low reflectivity, it is preferably 1.60 or less, more preferably 1.58 or less.
  • the glass transition temperature (Tg) of resin ⁇ is preferably 70° C. or higher, more preferably 80° C. or higher, and more preferably 90° C. or higher.
  • the temperature is preferably 350° C. or lower, more preferably 300° C. or lower, and more preferably 250° C. or lower.
  • the apparent viscosity ⁇ 240, ⁇ of the resin ⁇ at a shear rate of 100 (1/s) at 240° C. is preferably higher than the apparent viscosity ⁇ 240, ⁇ of the resin ⁇ . , preferably 400 (Pa s) to 10000 (Pa s), more preferably 600 (Pa s) or more or 9000 (Pa s) or less, among which 800 (Pa s) ) or more or 8000 (Pa ⁇ s) or less.
  • the resin ⁇ examples include at least one selected from the amorphous polyester resins exemplified for the resin ⁇ and the polycarbonate resins other than those exemplified for the resin ⁇ .
  • Examples thereof include 4,4'-dioxydiarylalkane-based polycarbonates such as 2,2-bis(4-hydroxyphenyl)propane-based polycarbonates (bisphenol A-based polycarbonates).
  • the resins ⁇ and ⁇ include the following combinations, and these resins ⁇ and ⁇ preferably constitute the dispersed phase (II).
  • Resins ⁇ and ⁇ are both amorphous polyester resins. That is, the first layer contains two or more amorphous polyester resins.
  • the resin ⁇ is an amorphous polyester resin, and the resin ⁇ is a polycarbonate resin other than those exemplified for the resin ⁇ . That is, the first layer contains an amorphous polyester resin and a polycarbonate resin (excluding the polycarbonate resin containing the structural unit (a)).
  • resin ⁇ (the resin with the higher content among the amorphous polyester resins in the dispersed phase (II)) and resin ⁇ (among the amorphous polyester resins in the dispersed phase (II)
  • the content mass ratio of the resin having a smaller content is preferably 50:50 to 95:5, more preferably 50:50 to 90:10, further preferably 50:50 to 85:15, and 50:50 to 80 :20 is even more preferred.
  • the content mass ratio of the resin ⁇ and the resin ⁇ is preferably 50:50 to 95:5, more preferably 50:50 to 90:10, further preferably 50:50 to 85:15. :50 to 80:20 is even more preferable.
  • the average refractive index of the resin ⁇ is preferably higher than that of the resin ⁇ . Even more preferable. On the other hand, from the viewpoint of low reflectivity, it is preferably 1.64 or less, more preferably 1.62 or less, and even more preferably 1.60 or less.
  • the glass transition temperature (Tg) of resin ⁇ is preferably 70° C. or higher, more preferably 80° C. or higher, and more preferably 90° C. or higher.
  • the temperature is preferably 350° C. or lower, more preferably 300° C. or lower, and more preferably 250° C. or lower.
  • the apparent viscosity ⁇ 240, ⁇ of the resin ⁇ at a shear rate of 100 (1/s) at 240° C. is preferably higher than the apparent viscosity ⁇ 240, ⁇ of the resin ⁇ . , preferably 400 (Pa s) to 10000 (Pa s), more preferably 600 (Pa s) or more or 9000 (Pa s) or less, among which 800 (Pa s) ) or more or 8000 (Pa ⁇ s) or less.
  • the dispersed phase volume of the first layer is preferably 20 ⁇ m 3 or more, more preferably 30 ⁇ m 3 or more, and even more preferably 40 ⁇ m 3 or more at the central portion in the thickness direction. Among them, it is preferably 50 ⁇ m 3 or more, more preferably 60 ⁇ m 3 or more, and even more preferably 70 ⁇ m 3 or more. Also, it is preferably 120 ⁇ m 3 or less, more preferably 110 ⁇ m 3 or less, even more preferably 100 ⁇ m 3 or less, and even more preferably 90 ⁇ m 3 or less.
  • the volume of the dispersed phase in the first layer is equal to or greater than the above lower limit, the dispersed diameters in the TD direction and the thickness direction are appropriately large, so that the reflection per dispersed phase can be reduced.
  • the dispersion diameter in the MD direction is moderately large, the anisotropic light diffusibility is also improved.
  • the dispersed phase volume is equal to or less than the above upper limit, the dispersion diameter in the TD direction and the thickness direction does not become too large, so the vicinity of the direction inclined 60° from the normal N direction of the light diffusion film surface to the light diffusion direction.
  • An ideal island component with strong diffusivity can be formed, and an optimum dispersion structure can be obtained to enhance the anisotropic light diffusibility.
  • the dispersed phase volume of the first layer is preferably 10 ⁇ m 3 or more, more preferably 15 ⁇ m 3 or more, and 20 ⁇ m in the surface layer and/or back layer in the thickness direction. More preferably, it is 3 or more. Among them, it is preferably 25 ⁇ m 3 or more, more preferably 30 ⁇ m 3 or more, and even more preferably 35 ⁇ m 3 or more. Also, it is preferably 120 ⁇ m 3 or less, more preferably 110 ⁇ m 3 or less, even more preferably 100 ⁇ m 3 or less, and even more preferably 90 ⁇ m 3 or less.
  • the dispersed phase volume was calculated by calculating the average dispersed diameter in the MD direction, the average dispersed diameter in the TD direction, and the average dispersed diameter in the thickness direction by the method described later, and assuming that the dispersed phase (II) was elliptical. value.
  • the “central portion in the thickness direction” refers to an area corresponding to ⁇ 15% of the thickness of the light diffusion film from the center in the thickness direction of the light diffusion film
  • the “surface layer and / or back in the thickness direction “Layer portion” refers to a region corresponding to 35% of the thickness of the light diffusion film from the front surface or back surface in the thickness direction of the light diffusion film.
  • the dispersed phase area in the TD cross section of the first layer is preferably 2 ⁇ m 2 or more, more preferably 2.5 ⁇ m 2 or more, and even more preferably 3 ⁇ m 2 or more at the central portion in the thickness direction. . Among them, it is preferably 3.5 ⁇ m 2 or more, more preferably 4 ⁇ m 2 or more. Also, it is preferably 100 ⁇ m 2 or less, more preferably 80 ⁇ m 2 or less, even more preferably 50 ⁇ m 2 or less, and even more preferably 30 ⁇ m 2 or less.
  • the dispersed phase area in the TD cross section of the first layer is at least the above lower limit, the dispersion diameters in the TD direction and the thickness direction are appropriately large, so that the reflection per dispersed phase can be reduced.
  • the dispersed phase area in the TD cross section is equal to or less than the above upper limit, the dispersion diameter in the TD direction and the thickness direction does not become too large, so the light diffusion film is tilted at 60° from the normal N direction of the surface of the light diffusion film to the light diffusion direction.
  • An ideal island component with strong diffusivity can be formed in the vicinity of the polar direction, and an optimum dispersion structure can be obtained to enhance the anisotropic light diffusibility.
  • the dispersed phase area in the TD cross section of the first layer is preferably 1 ⁇ m 2 or more, more preferably 1.5 ⁇ m 2 or more in the surface layer portion and/or the back layer portion in the thickness direction. is more preferable, and 2 ⁇ m 2 or more is even more preferable. Among them, it is preferably 2.5 ⁇ m 2 or more, more preferably 3 ⁇ m 2 or more, still more preferably 3.5 ⁇ m 2 or more, and even more preferably 4 ⁇ m 2 or more. Also, it is preferably 100 ⁇ m 2 or less, more preferably 80 ⁇ m 2 or less, even more preferably 50 ⁇ m 2 or less, and even more preferably 30 ⁇ m 2 or less.
  • the dispersed phase area is calculated by calculating the average dispersion diameter in the TD direction and the average dispersion diameter in the thickness direction in the TD cross section of the present light diffusion film by the method described later, and assuming that the dispersed phase (II) is elliptical. is the value
  • TD cross section refers to a cross section obtained by cutting the present light diffusion film in the TD direction at the center of the MD direction and having sides in the TD direction and the thickness direction of the film as shown in FIG. .
  • MD cross section refers to a cross section in which the present light diffusion film is cut in the MD direction at the center of the TD direction, and as shown in FIG. Say.
  • the light diffusion film preferably has a dispersed structure in which the island portions of the sea-island structure in the first layer extend in the MD direction and are dispersed in the sea portions.
  • the ratio of the average dispersion diameter in the MD direction to the average dispersion diameter in the TD direction of the dispersed phase (II) is the central part in the thickness direction and the surface part in the thickness direction and/or in the back layer, it is preferably 1.1 or more and 120 or less, more preferably 2 or more or 60 or less, more preferably 3 or more or 30 or less, especially 5 or more Alternatively, it is more preferably 25 or less.
  • the size of the dispersed component (dispersed phase (II)) in the MD direction of the film is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, still more preferably 10 ⁇ m or more, even more preferably 15 ⁇ m or more, and 20 ⁇ m or more at the central portion in the thickness direction. is particularly preferred.
  • it is preferably 60 ⁇ m or less.
  • the average dispersion diameter in the MD direction is preferably 1.5 ⁇ m or more, more preferably 2.5 ⁇ m or more, and is preferably 5 ⁇ m or more in the surface layer portion and/or the back layer portion in the thickness direction. More preferably, it is 10 ⁇ m or more, even more preferably 15 ⁇ m or more. On the other hand, from the viewpoint of morphology control, it is preferably 60 ⁇ m or less.
  • the average dispersion diameter in the direction perpendicular to the MD direction (TD direction) of the film is preferably 0.5 to 10 ⁇ m at the central portion in the thickness direction, especially 0.8 ⁇ m or more or 7 ⁇ m. It is more preferably 1 ⁇ m or more or 5 ⁇ m or less.
  • the average dispersion diameter in the TD direction is preferably 0.4 to 10 ⁇ m, more preferably 0.5 ⁇ m or more or 7 ⁇ m or less in the surface layer and / or back layer in the thickness direction. Among them, it is more preferably 0.6 ⁇ m or more or 5 ⁇ m or less.
  • the average dispersion diameter in the thickness direction of the film is preferably 0.1 to 10 ⁇ m, more preferably 0.5 ⁇ m or more or 7 ⁇ m or less, at the central portion in the thickness direction.
  • the thickness is more preferably 1 ⁇ m or more or 5 ⁇ m or less.
  • the average dispersion diameter in the thickness direction of the film is preferably 0.1 to 10 ⁇ m, more preferably 0.2 ⁇ m or more or 7 ⁇ m or less, in the surface layer portion and/or the back layer portion in the thickness direction.
  • the thickness is more preferably 0.3 ⁇ m or more or 5 ⁇ m or less.
  • any of the above average dispersion diameters can be obtained by photographing the cross section of the corresponding portion with a transmission electron microscope (TEM) or scanning electron microscope (SEM), and measuring the dispersion diameter in the photographing range using the free software "ImageJ". It is a value calculated as an average of all dispersion diameters within a range that can be analyzed and confirmed.
  • the photographing range may be appropriately adjusted depending on the size of the dispersed phase (II), but is preferably a range in which 10 or more dispersed phases (II) can be observed.
  • the discharge amount Q (kg / h) and the screw rotation speed N (rpm)
  • the ratio Q/N (kg/h/rpm)
  • the apparent viscosity ratio ⁇ 240, ⁇ / 240, ⁇ of the resins ⁇ and ⁇ forming the first layer at 240°C and a shear rate of 100 (1/s) is 1.5 to 15. is preferably 1.8 or more or 10 or less, more preferably 2 or more or 5 or less.
  • the light diffusion film may have a second layer on at least one surface of the first layer.
  • the provision of the second layer can suppress damage to other layers.
  • the first layer has a sea-island structure consisting of the continuous phase (I) and the dispersed phase (II)
  • shear stress is generally likely to be applied to the front and back layers during film formation.
  • the dispersion diameter of the surface layer portion and/or the back layer portion tends to be small.
  • the present light diffusion film includes the second layer, the shear stress applied to the front and back sides of the first layer during film production can be reduced, so that the dispersed phase (II) on the front and back sides of the first layer
  • the dispersion diameter can be increased, and both excellent anisotropic light diffusibility and low reflectivity can be achieved.
  • the second layer preferably has a continuous phase (Ib) composed of at least one selected from the thermoplastic resins exemplified for the first layer.
  • continuous phase (Ib) means a phase in which individual domains are connected without isolation from a macroscopic point of view, but it does not matter if there is a part that is not connected.
  • the continuous phase (Ib) of the second layer is preferably formed from a resin having an average refractive index of 1.45 to 1.53. More preferably, it is formed from a resin having a viscosity of 1.51 or more.
  • the continuous phase (Ib) contained in the second layer is preferably formed from a resin having a glass transition temperature of 90° C. or higher from the viewpoint of enhancing the heat resistance of the present light diffusion film.
  • the glass transition temperature of the resin constituting the continuous phase (Ib) contained in the second layer is preferably 90° C. or higher, more preferably 100° C. or higher, and more preferably 110° C. or higher. is more preferable, and 120° C. or higher is even more preferable.
  • the temperature is preferably 350° C. or lower, more preferably 300° C. or lower, and even more preferably 250° C. or lower.
  • the second layer preferably has a surface hardness of HB or higher, more preferably F or higher.
  • a resin having high hardness as the main component resin constituting the second layer.
  • it is not limited to this method.
  • the continuous phase (Ib) of the second layer is preferably formed from a polycarbonate resin or polymethyl methacrylate containing the structural unit (a) derived from the dihydroxy compound.
  • a polycarbonate resin or polymethyl methacrylate containing the structural unit (a) derived from the dihydroxy compound from the viewpoint of transparency, stretchability, heat resistance, low reflectivity, anisotropic light diffusibility, realization of high hardness, etc., it is preferable to form a polycarbonate resin containing the structural unit (a) derived from the above dihydroxy compound. Especially preferred.
  • a resin containing 50 mol% or more of the structural unit (a) derived from a dihydroxy compound is particularly preferable, and a resin containing 55 mol% or more of the structural unit (a) is more preferable, and a resin containing 60 mol% or more of the structural unit (a). is more preferred.
  • the continuous phase (Ib) of the second layer contains the same thermoplastic resin as the thermoplastic resin forming the continuous phase (I) of the first layer.
  • the first layer has a sea-island structure with the continuous phase (I) and the dispersed phase (II)
  • the composition of the resin constituting the continuous phase (I) of the first layer and the continuous phase (Ib) of the second layer When the resin is of the same type, reflection is less likely to occur at the interface between the first layer and the second layer, so that both excellent anisotropic light diffusion and low reflectivity can be achieved.
  • thermoplastic resin of the same type as the thermoplastic resin forming the continuous phase (I) of the first layer means that a polymer composed of the same or similar monomers is used as the base resin.
  • the monomers constituting the main repeating units of the thermoplastic resin component may be the same or of the same type, including the case where the degrees of polymerization are different.
  • the monomer ratio in addition to the case where the monomer ratio is different, it includes the case where the copolymerizable monomer is different, and also includes the case where the degree of polymerization is different as described above. .
  • the second layer preferably does not substantially have a dispersed phase, particularly a dispersed phase having a refractive index different from that of the continuous phase (Ib).
  • the phrase “substantially does not have a dispersed phase having a refractive index different from that of the continuous phase (Ib)” means that the cross-sectional area of the second layer in the TD direction (total area including the continuous phase and the dispersed phase) is It means that the area ratio of the phase (Ib) and the dispersed phase having a different refractive index is 20 area% or less, more preferably 10 area% or less, and most preferably 5 area% or less. It means that there is The dispersed phase having the same refractive index as that of the continuous phase (Ib) travels straight at the interface between the continuous phase (Ib) and the dispersed phase, so there is no risk that the reflectance will increase. can.
  • the second layer is laminated on at least one side of the first layer, e.g. Adjacent lamination is particularly preferred.
  • the terms “upper side” and “upper side” refer to the surface that was in contact with the cast surface
  • the terms “lower side” and “lower side” refer to the side that was in contact with the cast surface. indicates the opposite surface.
  • the present light diffusion film can be used so that either the upper surface side (upper side) or the lower surface side (lower side) is arranged on the display surface side (viewing side), and the display It can be used so that either the upper surface side (upper side) or the lower surface side (lower side) is arranged on the surface side opposite to the surface side (viewing side). In other words, the present light diffusion film can be used without distinguishing between the upper surface side (upper side) and the lower surface side (lower side).
  • the present light diffusion film is usually used by laminating with an adhesive layer, but when the second layer is provided, the interface between the adhesive layer and the first layer having a dispersed phase with a high refractive index is eliminated. and the reflectance can be reduced.
  • any one of the following aspects is more preferable for the present light diffusion film.
  • - Having at least a first layer capable of scattering incident light in the direction of travel of the light, and having a ratio of the 60° brightness ratio to the front brightness ratio (60° brightness ratio/front brightness ratio) of 0.30 or more and 0.60 It is below.
  • - Having at least a first layer capable of scattering incident light in the direction of travel of the light, and having a ratio of the 60° brightness ratio to the front brightness ratio (60° brightness ratio/front brightness ratio) of 0.30 or more and 0.50 It is below.
  • - comprising a first layer having a sea-island structure composed of a continuous phase (I) and a dispersed phase (II), wherein the dispersed phase volume at the central portion in the thickness direction of the first layer is 20 ⁇ m 3 or more and 120 ⁇ m 3 or less;
  • the ratio of the average dispersion diameter in the MD to the average dispersion diameter in the TD of the phase (II) is 3 or more at the central portion in the thickness direction.
  • - comprising a first layer having a sea-island structure composed of a continuous phase (I) and a dispersed phase (II), wherein the dispersed phase volume at the central portion in the thickness direction of the first layer is 20 ⁇ m 3 or more and 120 ⁇ m 3 or less;
  • the area of the dispersed diameter in the TD cross section at the central portion in the thickness direction of the phase (II) is 2 ⁇ m 2 or more.
  • It has a sea-island structure with a continuous phase (I) and a dispersed phase (II), and at least one of the continuous phase (I) and the dispersed phase (II) contains a thermoplastic resin having an average refractive index of 1.53 or less.
  • thermoplastic resin having a laminated structure comprising at least a first layer and a second layer, the first layer having a sea-island structure with a continuous phase (I) and a dispersed phase (II), and the second layer , a continuous phase (Ib) laminated on at least one surface side of the first layer and containing the same thermoplastic resin as the thermoplastic resin forming the continuous phase (I) of the first layer .
  • the first layer having a sea-island structure with a continuous phase (I) and a dispersed phase (II), and the second layer , which is laminated on at least one side of the first layer, has a continuous phase (Ib) containing a resin having a glass transition temperature of 90° C. or higher, and has a surface hardness of HB or higher.
  • the present light diffusion film may have a single layer structure consisting of only the first layer, or may have a multilayer structure including the first layer and the second layer. When it has a multilayer structure, it may have other layers in addition to the first layer and the second layer.
  • Examples of the multilayer structure include, for example, a second layer/first layer, two types of two layers, a second layer/first layer/second layer, a first layer/second layer/ Two kinds of three layers of the first layer; hard coat layer / second layer / first layer, second layer / first layer / hard coat layer, adhesive layer / second layer / first layer layer, second layer/first layer/adhesive layer 3 types 3 layers; hard coat layer/second layer/first layer/hard coat layer, adhesive layer/second layer/first layer Layer/adhesive layer, hard coat layer/second layer/first layer/second layer, adhesive layer/second layer/first layer/second layer, hard coat layer/first layer / second layer / first layer, adhesive layer / first layer / second layer / first layer 3 types 4 layers; hard coat layer / second layer / first layer / second layer / hard coat layer, adhesive layer / second layer / first layer / second layer / adhesive layer, hard coat layer / first layer / second layer / first Layer/hard
  • the present light diffusion film has a multilayer structure
  • at least one layer may be a layer having anisotropic light diffusing properties
  • the other layers may be layers having no anisotropic light diffusing properties.
  • all layers may be composed of an anisotropic light diffusion layer.
  • the anisotropic light diffusion layer serves as an intermediate layer.
  • the thickness of the first layer is preferably 10 to 90% of the thickness of the entire light diffusion film, more preferably 20% or more or 80% or less. , more preferably 30% or more or 70% or less.
  • the thickness of the second layer is preferably 5 to 90% of the thickness of the entire light diffusion film, especially 10% or more or 80% or less, especially 15% % or more or 70% or less.
  • the thickness ratio between the first layer and the second layer is preferably in the range of 0.1 to 30, especially 0 It is more preferably in the range of 0.2 or more or 20 or less, more preferably in the range of 0.3 or more or 10 or less, and more preferably in the range of 0.4 or more or 5 or less. preferable.
  • the first layer has a sea-island structure with the continuous phase (I) and the dispersed phase (II)
  • the first layer Since the shear stress applied to the front and back surfaces can be reduced, the dispersion diameter of the dispersed phase on the front and back surfaces of the first layer can be increased, and excellent anisotropic light diffusion and low reflectivity can be achieved.
  • the thickness of the light diffusion film is preferably 10-1000 ⁇ m.
  • excellent anisotropic light can be obtained by setting the film thickness to be suitable for the dispersion structure formed in the present light diffusion film. From the viewpoint of obtaining diffusibility, it is preferably 15 to 500 ⁇ m, more preferably 20 ⁇ m or more or 300 ⁇ m or less, and even more preferably 25 ⁇ m or more or 100 ⁇ m or less.
  • the light diffusion film is preferably oriented in at least one direction.
  • the first layer has a sea-island structure composed of the continuous phase (I) and the dispersed phase (II), as described above, it has a unique dispersed structure with island portions extending in the MD direction. It is preferred to have a dispersed structure in which the island portions are dispersed in the sea portion. In order to form such a dispersed structure, it is more preferable to be oriented in one direction.
  • the unidirectional orientation of the present light-diffusing film means that the island portions of the first layer are elongated in the MD direction in the cross-sectional view (MD cross-section) of the anisotropic light-diffusing film. You can check by checking.
  • the method for producing the present light diffusion film includes, for example, a mixed resin composition containing at least two thermoplastic resins, A method of forming a film by melting can be mentioned.
  • film-forming methods include a T-die casting method, a calendering method, and an inflation method. Among these methods, the T die casting method is preferable from the viewpoint of film formation stability and production efficiency.
  • a film insert method a melt extrusion method, an extrusion lamination method, a heat press method, a solution casting method, etc., can be used.
  • the melt extrusion method is particularly preferably used.
  • the resin compositions used for the first layer and the second layer are heated and melted in separate extruders, and laminated in a molten state by a method such as a coextrusion multilayer die method or a feed block method.
  • a co-extrusion method can be mentioned in which the mixture is formed into a film by inflation, T-die casting, or the like.
  • the extrusion temperature of the film is preferably in the range of approximately 220°C to 300°C, more preferably in the range of 230°C to 280°C, although it depends on the flow characteristics of each resin.
  • the extrusion temperature is 220° C. or higher, the film can be sufficiently formed so that the molten resin can flow.
  • the diameter of the resin forming the dispersed phase (II) in the mixed resin composition can be controlled.
  • the orientation direction may be either the take-off (flow) direction (MD) of the film or the direction perpendicular to the MD (TD). From the viewpoint of controlling the diameter of the dispersed resin in the T die casting method, it is preferable to orient in the MD. That is, in the present light diffusion film, it is preferable that the axis (S axis) parallel to the orientation direction is MD, and the axis (P axis) perpendicular to the orientation direction and parallel to the film surface is TD. It will be.
  • the method for orientation is not particularly limited.
  • the method for orientation is not particularly limited.
  • Examples include a method of applying a draft to the MD, and a method of applying a draft to the MD by increasing the take-up speed when forming a film by the inflation method.
  • the method of drafting the sheet formed by the T-die casting method as described above in the MD is preferable from the viewpoint of controlling the diameter of the dispersed resin.
  • the draft is a process of stretching in the MD direction at a casting speed during film production.
  • the stretching method is not particularly limited as long as it is stretched in at least one direction, and may be a method of monoaxial stretching in the MD or TD direction or a method of biaxial stretching in the MD and TD directions. may
  • the present light-diffusing film can be in a form in which an adhesive layer is provided on one side or both sides, that is, in the form of a so-called anisotropic light-diffusing film with an adhesive layer (referred to as "this anisotropic light-diffusing film with an adhesive layer"). . That is, the anisotropic light-diffusing film with an adhesive layer has an adhesive layer on at least one surface of the light-diffusing film.
  • the pressure-sensitive adhesive layer preferably contains at least one or more selected from rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, and vinyl-based pressure-sensitive adhesives. preferably included as Among them, it is preferable to contain an acrylic pressure-sensitive adhesive, and it is particularly preferable to contain it as a main component.
  • the main component means a pressure-sensitive adhesive component that accounts for 50% by mass or more of the pressure-sensitive adhesive components constituting the pressure-sensitive adhesive layer, and more than 60% by mass, more than 70% by mass, and more than 70% by mass. It means an adhesive component that accounts for 80% by mass or more, of which 90% by mass or more (including 100% by mass).
  • the acrylic pressure-sensitive adhesive has a refractive index of about 1.49, by using it as a main component of the pressure-sensitive adhesive layer laminated on the light-diffusing film, reflection at the interface between the light-diffusing film and the pressure-sensitive adhesive layer can be reduced. can be reduced.
  • Examples of methods for forming an adhesive layer on the light diffusion film include a method of laminating an adhesive sheet formed into a film shape with a laminator or the like, and a method of coating the light diffusion film with an adhesive.
  • This light diffusion film can be used for image display devices such as personal computers, televisions (TV), mobile terminals (PDA), mobile phones, smartphones, etc.
  • image display devices such as personal computers, televisions (TV), mobile terminals (PDA), mobile phones, smartphones, etc.
  • LCD liquid crystal display devices
  • ELD electroluminescence displays
  • PDP Plasma Display Panel
  • CRT Cathode Tube Display
  • SED Surface Electrolytic Display
  • Electronic Paper Transparent Screen
  • LED Diffusion Plate Head-Up Display
  • TV Diffusion Plate etc.
  • the present light diffusion film is particularly used by bonding between the display surface of the image display device and the antireflection film, or between the antireflection film and the polarizing plate. preferably.
  • the light diffusion film may be used as a film having both the light diffusion properties and the necessary properties of the various constituent members, as a substitute for the various films of the constituent members.
  • the orientation direction of the rod-shaped island phase of the film is parallel to the length direction of the cold cathode tube of the large liquid crystal TV.
  • the anisotropic light-diffusing film of the present invention is used in a projection type image display device, it is preferable to arrange the anisotropic light-diffusing film of the present invention as a screen in front.
  • Image light projected from an image display engine such as a CRT, LCD, or DMD of a projection type image display device is projected onto a screen by an optical system such as a reflecting mirror.
  • an optical system such as a reflecting mirror.
  • Resin A-1 isosorbide-based polycarbonate resin (average refractive index: 1.506, Tg: 120 ° C., apparent viscosity (240 ° C., 100 (1 / s)): 740 Pa s, 1,4-cyclohexanedimethanol 31 .1 mol%, isosorbide 68.9 mol%)
  • Resin A-2 isosorbide-based polycarbonate resin (average refractive index: 1.516, Tg: 126 ° C., apparent viscosity (240 ° C., 100 (1 / s)): 830 Pa s, tricyclodecanedimethanol 33.3 mol %, isosorbide 66.7 mol%)
  • Resin A-3 isosorbide-based polycarbonate resin (average refractive index: 1.502, Tg: 98 ° C., apparent viscosity (240 ° C.
  • Resin B-1 Amorphous polyethylene terephthalate resin (average refractive index: 1.539, Tg: 109°C, apparent viscosity (240°C, 100 (1/s)): 1000 Pa s, acid component: 100 mol of terephthalic acid %, diol components: ethylene glycol 51.5 mol%, diethylene glycol 5.4 mol%, spiroglycol 43.1 mol%)
  • Resin B-2 Amorphous polyester resin (average refractive index: 1.552, Tg: 119 ° C., apparent viscosity (240 ° C., 100 (1 / s)): 2500 Pa s, acid component: terephthalic acid 100 mol% , diol components: 1,4-cyclohexanedimethanol 65.7 mol%, 2,2,4,4-tetramethyl-1,3-cyclobutanediol 34.3 mol%)
  • Resin B-3 Amorphous polyester resin (average refractive index: 1.539, Tg:
  • Resin C-1 acrylonitrile-styrene copolymer (AS resin) (average refractive index: 1.567, Tg: 108 ° C., apparent viscosity (240 ° C., 100 (1 / s)): 1240 Pa s)
  • Resin C-2 cyclic polyolefin resin (average refractive index: 1.534, Tg: 138 ° C., apparent viscosity (240 ° C., 100 (1 / s)): 3800 Pa s)
  • Resin C-3 cyclic polyolefin resin (average refractive index: 1.530, Tg: 100 ° C., apparent viscosity (240 ° C., 100 (1 / s)): 410 Pa s)
  • Resin C-4 polystyrene resin (average refractive index: 1.589, Tg: 100 ° C., apparent viscosity (240 ° C., 100 (1 / / s)
  • the glass transition temperature (Tg) of the resin used in each test example was determined according to JIS K7121: 2012 using a differential scanning calorimeter (for example, "DSC 8500” manufactured by PerkinElmer Japan). Measurement was performed under conditions of a temperature range of 0 to 200°C and a heating rate of 10°C/min.
  • Test Example 2 the central part in the thickness direction of the first layer (intermediate layer) of the film (the area corresponding to ⁇ 15% of the thickness of the light diffusion film from the center) and the front and back parts in the thickness direction (from the front or back to the main 35% of the thickness of the light diffusion film) was photographed with a transmission electron microscope (TEM), the maximum dispersion diameter and the minimum dispersion diameter in the photographed range were measured, and the average dispersion diameter was calculated. The table shows the minimum and maximum values in parenthesis together with the average dispersion diameter.
  • the average dispersed diameter was calculated in the same manner as in Test Example 2 except that a scanning electron microscope (SEM) was used.
  • SEM scanning electron microscope
  • Test Example 4 the central part in the thickness direction of the first layer (intermediate layer) of the film (the area corresponding to ⁇ 15% of the thickness of the light diffusion film from the center) and the front and back parts in the thickness direction (from the front or back to the main 35% of the thickness of the light diffusion film) is photographed with a scanning electron microscope (SEM), and the dispersion diameter in the photographing range is analyzed using the free software "ImageJ". An average dispersion diameter in the thickness direction was calculated as an average.
  • SEM scanning electron microscope
  • Test Example 2 the central part in the thickness direction of the first layer (intermediate layer) of the film (the area corresponding to ⁇ 15% of the thickness of the light diffusion film from the center) and the front and back parts in the thickness direction (from the front or back to the main 35% of the thickness of the light diffusion film) is photographed with a transmission electron microscope (TEM), the maximum dispersion diameter and the minimum dispersion diameter in the photographed range are measured, and the dispersion diameter as the average value was calculated, and the dispersion diameter ratio (MD dispersion diameter/TD dispersion diameter) was calculated from the average value.
  • the table shows the minimum and maximum values in parenthesis together with the dispersion diameter or dispersion diameter ratio as an average value.
  • the average dispersed diameter was calculated in the same manner as in Test Example 2 except that a scanning electron microscope (SEM) was used.
  • SEM scanning electron microscope
  • the central part in the thickness direction of the first layer (intermediate layer) of the film (the area corresponding to ⁇ 15% of the thickness of the light diffusion film from the center) and the front and back parts in the thickness direction (from the front or back to the main 35% of the thickness of the light diffusion film) is photographed with a scanning electron microscope (SEM), and the dispersion diameter in the photographed range is analyzed using the free software "ImageJ", and the range that can be confirmed.
  • the average dispersion diameter in the MD direction and the TD direction was calculated as the average of all the dispersion diameters of , and the dispersion diameter ratio (MD average dispersion diameter/TD average dispersion diameter) was calculated.
  • the average refractive index of the raw material used in each test example was measured according to JIS K7124 using an Abbe refractometer manufactured by Atago Co., Ltd., using a sodium D line (589 nm) as a light source.
  • the absolute value of the difference in refractive index between the continuous phase (I) and the dispersed phase (II) was defined as the refractive index difference.
  • the refractive index of the dispersed phase (II) was calculated from the compounding ratio in the dispersed phase (II) and the average refractive index of each resin.
  • Luminous reflectance R SCI and R SCE In Test Example 1, a spectrophotometer ("SC-T", manufactured by Suga Test Instruments Co., Ltd.) was used, with a white calibration standard plate attached to the main unit as a reference, a black background, a D65/2 light source, and a measurement range of ⁇ 5 mm. The luminous reflectance R SCI and the luminous reflectance R SCE were measured according to the method to obtain the luminous reflectance R SCI and the luminous reflectance R SCE .
  • SC-T spectrophotometer
  • Test Example 2 a spectrophotometer ("CM-600d", manufactured by Konica Minolta Co., Ltd.) was used, with a white calibration standard plate attached to the main unit as a reference, a black background (R SCI : 5.1), D65/2 Luminous reflectance R SCI and luminous reflectance R SCE were measured by a reflection method with a light source and a measurement range of ⁇ 8 mm to obtain luminous reflectance R SCI and luminous reflectance R SCE .
  • a film (PET film) made of polyethylene terephthalate having a thickness of 100 ⁇ m was laminated on both sides of the film prepared in each Test Example with an adhesive layer interposed therebetween.
  • Luminous reflectance R SCI and luminous reflectance R SCE were measured respectively to obtain luminous reflectance R SCI and luminous reflectance R SCE .
  • the adhesive layer was formed from a 150 ⁇ m-thick acrylic optical transparent adhesive sheet (“Clearfit (registered trademark)” manufactured by Mitsubishi Chemical Corporation).
  • the luminous reflectance R SCI and the luminous reflectance R SCE in the state where the PET film and the adhesive layer were laminated were 16.88 and 4.38 , respectively.
  • luminous reflectance R SCI and luminous reflectance R SCE were measured in the same manner as in Test Example 2 to obtain luminous reflectance R SCI and luminous reflectance R SCE .
  • Total light transmittance The total light transmittance of the film produced in each test example was measured according to JIS K7361-1.
  • the films 1 of Examples and Comparative Examples were fixed to a backlight unit 2, and light was made incident from the normal N direction of the film surface (thick arrow in FIG. 1).
  • the measured value (luminance C) was confirmed when the backlight unit 2 was tilted so that the luminance meter 3 was positioned in a direction tilted 60° from the normal N direction of the film surface to the light diffusion direction y.
  • the measured value (luminance B) when the backlight unit 2 is arranged so that the luminance meter 3 is positioned in the direction of the normal line N was confirmed, and the ratio (C/B) of the luminance C and the luminance B was calculated. .
  • a blank sample is fixed to the backlight unit, light is incident from the normal N direction of the film surface, and the measured value (luminance A) when the backlight unit is arranged so that the luminance meter is positioned in the normal N direction After confirmation, the ratio (B/A) of the luminance B and the luminance A was calculated.
  • a single layer sample of Resin A was used as a blank sample. The blank sample had a total light transmittance of 92% and a haze of 0.21%.
  • Tensile strength was measured according to the method described in JIS K7161-1, with a test length of 50 mm, a test width of 15 mm, a test speed of 200 mm/min, and a test temperature of room temperature. Also, the tensile strength ratio ⁇ MD / ⁇ TD was calculated from the tensile strength ⁇ MD in the MD direction and the tensile strength ⁇ TD in the TD direction.
  • ⁇ Test Example 1>> ⁇ Test Example 1-1> After sufficiently mixing 60% by mass of resin A-1 and 40% by mass of resin B-1, while feeding with a constant mass feeder, extrusion kneading at 240 ° C. with a ⁇ 25 mm twin screw extruder (discharge rate Q ( kg/h) and the screw rotation speed N (rpm): Q/N 0.016 (kg/h/rpm)), and cooled and solidified at a casting speed of 0.8 m/min to form an anisotropic light with a thickness of 69 ⁇ m. A diffusion film was produced.
  • a film with a thickness of 160 ⁇ m was produced by The resulting film was cut out, tilted at 90°, passed through a tenter heated to a stretching temperature of 150°C, and stretched 3 times in the MD to produce an anisotropic light diffusion film with a thickness of 68 ⁇ m.
  • the continuous phase (I) made of resin B-3 had a shape extending in the MD direction, made of resin B-5 and resin B-6. It was confirmed to have a sea-island structure in which the dispersed phase (II) is dispersed.
  • Each of the anisotropic light diffusion films obtained in Test Examples 1-1 to 1-4 has a sea-island structure in which the dispersed phase (II) having a shape extending in the MD direction is dispersed in the continuous phase (I).
  • the continuous phase (I) contained a thermoplastic resin having an average refractive index of 1.53 or less. From the above test examples and the results of the tests conducted by the present inventors so far, it has been found that the If at least one of them contains a thermoplastic resin having an average refractive index of 1.53 or less, it can be considered that both anisotropic light diffusibility and low reflectivity can be achieved.
  • test Examples 1-3 and 1-4 had dispersion diameters in the TD direction and thickness direction as compared with the films obtained in Test Examples 1-5 to 1-7. It was large, and the ratio of dispersion diameter (MD dispersion diameter/TD dispersion diameter) and refractive index difference were more appropriate.
  • Test Examples 1-1 and 1-2 also contain a thermoplastic resin having an average refractive index of 1.53 or less, and the refractive index difference between the continuous phase (I) and the dispersed phase (II) is about the same.
  • the dispersion diameters in the thickness direction, the MD direction and the TD direction and the ratio of the dispersion diameters are approximately the same as those in Test Examples 1-3 and 1-4. Therefore, the anisotropic light diffusing films obtained in Test Examples 1-1 to 1-4 have further excellent anisotropic light diffusibility for diffusing light in a specific direction and low reflectivity. can be considered to exist.
  • the second layer-forming composition resin A-1 was preheated using an oven so as to be held at 110 ° C.
  • a cross section of the obtained anisotropic light-diffusing film was observed with a transmission electron microscope.
  • a first layer having a sea-island structure in which the dispersed phase (I) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase. At this time, the first layer contains a dispersed phase, and the dispersed phase can be confirmed up to the interface with the second layer, so the interface between the first layer and the second layer was confirmed. .
  • a cross section of the obtained anisotropic light-diffusing film was observed with a transmission electron microscope.
  • a first layer having a sea-island structure in which the dispersed phase (I) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase.
  • 60% by mass of Resin A-3 and 40% by mass of Resin B-2 were thoroughly mixed and preheated using an oven to hold at 90° C. for 6 hours.
  • the same procedure as in Test Example 2-2 was performed except that resin A-3 was preheated in an oven so as to be held at 90° C. for 6 hours, and then supplied to the extruder.
  • an anisotropic light diffusion film (second layer/first layer/second layer: 19.5 ⁇ m/34 ⁇ m/19.5 ⁇ m) having a thickness of 73 ⁇ m was produced.
  • the continuous phase (II) made of the resin A-3 was composed of the resin B-2 exhibiting a shape extending in the MD direction.
  • a first layer having a sea-island structure in which the dispersed phase (I) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase.
  • Example 2-4 An anisotropic light diffusion film having a thickness of 69 ⁇ m (first 2 layers/first layer/second layer: 18.5 ⁇ m/32 ⁇ m/18.5 ⁇ m).
  • a cross section of the obtained anisotropic light-diffusing film was observed with a transmission electron microscope.
  • a first layer having a sea-island structure in which the dispersed phase (I) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase.
  • the continuous phase (II) made of the resin A-3 was composed of the resin B-2 exhibiting a shape extending in the MD direction.
  • a first layer having a sea-island structure in which the dispersed phase (I) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase.
  • Test Example 2-5 also has a second layer, and the refractive index difference between the continuous phase (I) and the dispersed phase (II) is about the same.
  • the dispersion diameters in the thickness direction, the MD direction and the TD direction and the ratio of the dispersion diameters (MD dispersion diameter/TD dispersion diameter) are estimated to be approximately the same as in Test Examples 2-1 to 2-4.
  • the composition for forming the first layer 60% by mass of resin A-4 and 40% by mass of resin B-2 are thoroughly mixed, and preheated using an oven so as to be held at 110 ° C. for 17 hours.
  • the composition for forming the second layer resin A-4 was preheated using an oven so as to be held at 110° C.
  • the continuous phase (I) composed of resin A-4 was composed of resin B-2, which exhibited a shape extending in the MD direction.
  • a first layer having a sea-island structure in which the dispersed phase (II) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase. At this time, the first layer contains a dispersed phase, and the dispersed phase can be confirmed up to the interface with the second layer, so the interface between the first layer and the second layer was confirmed. .
  • Example 3-2> As the composition for forming the first layer, 60% by mass of Resin A-1 and 40% by mass of Resin B-2 were thoroughly mixed and preheated using an oven to hold at 110° C. for 17 hours. On the other hand, as the second layer-forming composition, Resin A-1 was preheated using an oven so as to be held at 110 ° C. for 17 hours, and then supplied to the extruder, except that it was supplied to the extruder. Similarly, an 81 ⁇ m-thick anisotropic light diffusion film (second layer/first layer/second layer: 25.5 ⁇ m/30 ⁇ m/25.5 ⁇ m) was produced.
  • the continuous phase (I) made of the resin A-1 was made of the resin B-2 exhibiting a shape extending in the MD direction.
  • a first layer having a sea-island structure in which the dispersed phase (II) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase.
  • Example 3-3 As the composition for forming the first layer, 60% by mass of Resin A-1 and 40% by mass of Resin B-2 were thoroughly mixed and preheated using an oven to hold at 110° C. for 17 hours. On the other hand, as the second layer-forming composition, resin A-4 was preheated using an oven so as to be held at 110 ° C. for 17 hours, and then supplied to the extruder Same as Test Example 3-1. Then, an anisotropic light diffusion film (second layer/first layer/second layer: 23.5 ⁇ m/29 ⁇ m/23.5 ⁇ m) having a thickness of 76 ⁇ m was produced.
  • second layer/first layer/second layer 23.5 ⁇ m/29 ⁇ m/23.5 ⁇ m
  • the continuous phase (I) made of the resin A-1 was made of the resin B-2 exhibiting a shape extending in the MD direction.
  • a first layer having a sea-island structure in which the dispersed phase (II) is dispersed was confirmed. It was also confirmed that the second layer did not have a dispersed phase.
  • Example 3-4 As the first layer-forming composition, 59% by weight of Resin A-4 and 41% by weight of Resin C-1 were thoroughly mixed and preheated using an oven to hold at 85° C. for 17 hours. On the other hand, as the second layer-forming composition, resin A-4 was preheated using an oven so as to be held at 110 ° C. for 17 hours, and then supplied to the extruder Same as Test Example 3-1. Then, an anisotropic light diffusion film (second layer/first layer/second layer: 19 ⁇ m/29 ⁇ m/19 ⁇ m) having a thickness of 67 ⁇ m was produced.
  • ⁇ Test Example 3-5> As the composition for forming the first layer, 55% by weight of Resin A-4 and 45% by weight of Resin B-4 were thoroughly mixed and preheated using an oven to hold at 110° C. for 17 hours. On the other hand, as the second layer-forming composition, resin A-4 was preheated using an oven so as to be held at 110 ° C. for 17 hours, and then supplied to the extruder Same as Test Example 3-1. Then, an anisotropic light diffusion film (second layer/first layer/second layer: 18 ⁇ m/29 ⁇ m/18 ⁇ m) having a thickness of 65 ⁇ m was produced.
  • Resin A-1 and 41% by weight of Resin C-1 were thoroughly mixed and preheated using an oven to hold at 85° C. for 17 hours.
  • resin A-1 was preheated using an oven so as to be held at 110 ° C. for 17 hours, and then supplied to the extruder Same as Test Example 3-1. Then, an anisotropic light diffusion film (second layer/first layer/second layer: 25.5 ⁇ m/29 ⁇ m/25.5 ⁇ m) having a thickness of 80 ⁇ m was produced.
  • Example 3-7 As the composition for forming the first layer, 55% by mass of Resin A-1 and 45% by mass of Resin B-4 were thoroughly mixed and preheated using an oven to hold at 110° C. for 17 hours. On the other hand, as the second layer-forming composition, resin A-1 was preheated using an oven so as to be held at 110 ° C. for 17 hours, and then supplied to the extruder Same as Test Example 3-1. Then, an anisotropic light diffusion film (second layer/first layer/second layer: 22.5 ⁇ m/28 ⁇ m/22.5 ⁇ m) having a thickness of 73 ⁇ m was produced.
  • the second layer-forming composition resin A-3 was preheated using an oven so as to be held at 90° C.
  • FIGS. 2 and 3 show the MD cross section and TD cross section of the anisotropic light diffusion film of Test Example 4-1, respectively. Arrows in the figure indicate the interface between the first layer and the second layer.
  • ⁇ Test Example 4-2> In the same manner as in Test Example 4-2 except that 58% by mass of resin A-3, 5% by mass of resin B-3, and 37% by mass of resin B-4 were used as the first layer-forming composition, the thickness was 82 ⁇ m. of the anisotropic light diffusion film (second layer/first layer/second layer: 24.5 ⁇ m/33 ⁇ m/24.5 ⁇ m).
  • FIGS. 4 and 5 show the MD cross section and TD cross section of the anisotropic light diffusion film of Test Example 4-2, respectively. Arrows in the figure indicate the interface between the first layer and the second layer.
  • extruder cylinder temperature: 250 ° C.
  • FIGS. 6 and 7 show MD cross sections and TD cross sections of the anisotropic light diffusion film of Test Example 4-3, respectively. Arrows in the figure indicate the interface between the first layer and the second layer.
  • FIGS. 8 and 9 show the MD cross section and TD cross section of the anisotropic light diffusion film of Test Example 4-4, respectively. Arrows in the figure indicate the interface between the first layer and the second layer.
  • resin A-1 was preheated using an oven so as to be held at 110° C. for 17 hours, and then supplied to an extruder (cylinder temperature: 230° C.) and melted. bottom.
  • resin C-3 is preheated using an oven so as to be held at 70 ° C. for 17 hours, and then supplied to an extruder (cylinder temperature: 230 ° C.) and melted. bottom.
  • FIGS. 10 and 11 show the MD cross section and TD cross section of the anisotropic light diffusion film of Test Example 4-7, respectively. Arrows in the figure indicate the interface between the first layer and the second layer.
  • FIGS. 12 and 13 show the MD cross section and TD cross section of the anisotropic light diffusion film of Test Example 4-8, respectively.
  • All of the anisotropic light diffusion films obtained in Test Examples 4-1 to 4-6 have a 60° luminance ratio/front luminance ratio within the preferred range of the present invention, a high 60° luminance ratio, and all light rays It also has excellent transmittance and low reflectivity. Therefore, by adjusting the 60° luminance ratio/front luminance ratio, it can be said that the front luminance and the anisotropic light diffusion property are well balanced, and the brightness and visibility at a wide viewing angle are improved when mounted on a display.
  • all of the anisotropic light diffusion films obtained in Test Examples 4-1 to 4-6 are formed by dispersing the dispersed phase (II) exhibiting a shape extending in the MD direction in the continuous phase (I). It has a sea-island structure and high haze, so it contains a large amount of dispersion components and is excellent in anisotropic light diffusion.
  • the tensile strength is within the preferred range of the present invention, and the anisotropy of the tensile strength is small, so it is thought that interfacial separation between the continuous phase (I) and the dispersed phase (II) is unlikely to occur. It can be said that the reflection is small, ie, the low reflectivity is excellent, and the total light transmittance is high.
  • the average dispersion diameter in the MD direction with respect to the average dispersion diameter in the TD direction at the center in the thickness direction of the first layer is within the preferred range of the present invention, and the anisotropic light diffusibility is excellent.
  • the dispersed phase volume in the central part in the thickness direction and the dispersed phase area in the TD cross section are within the preferable range of the present invention, the dispersed diameter in the TD direction and the thickness direction are moderately large, so per dispersed phase.
  • the dispersion diameter in the TD direction and the thickness direction does not become too large, it has strong diffusivity in the vicinity of the direction inclined 60° from the normal N direction of the light diffusion film surface to the light diffusion direction. It can be said that an ideal island component can be formed and an optimum dispersion structure can be obtained to further enhance the anisotropic light diffusibility.
  • the 60° luminance ratio/front luminance ratio is smaller than the preferred range of the present invention, and the low reflectivity is Test Examples 4-1 to 4- 6, but inferior in 60° luminance ratio and total light transmittance.
  • the anisotropic light diffusion films of Test Examples 4-7 to 4-9 have low anisotropic light diffusion properties and low transmittance, and are insufficient in brightness and visibility when mounted on a display.
  • the anisotropic light diffusion film obtained in Test Example 4-7 had a sea-island structure in which the dispersed phase (II) having a shape extending in the MD direction was dispersed in the continuous phase (I). Since the haze is high, it contains many dispersed components, but the tensile strength is low and the anisotropy of the tensile strength is large. It is considered that the control of the diameter is difficult and the anisotropic light diffusing property tends to be low.
  • the volume of the dispersed phase at the central portion in the thickness direction is larger than the preferred range of the present invention, the dispersion diameters in the TD direction and the thickness direction become too large, and the light diffuses from the normal N direction of the surface of the light diffusion film.
  • An ideal island component having a strong diffusivity cannot be formed in the vicinity of a direction inclined 60° to the direction, and it can be considered that the anisotropic light diffusibility is inferior to that of Test Examples 4-1 to 4-6. can.
  • the anisotropic light diffusion film obtained in Test Example 4-8 has low anisotropy in tensile strength, so interfacial separation between the continuous phase (I) and the dispersed phase (II) is unlikely to occur, and the interfacial reflection is small. Although it has excellent low reflectivity, the haze is low, so the dispersion component is small. /TD average dispersion diameter) is smaller than the preferred range of the present invention, and it can be said that the anisotropic light diffusing property is inferior.
  • the dispersion diameter in the TD direction and the thickness direction is small, so that the reflection per dispersed phase is large, and the present light diffusion
  • An ideal island component with strong diffusivity could not be formed in the vicinity of the direction inclined 60° from the normal N direction of the film surface to the light diffusion direction, which was different from Test Examples 4-1 to 4-6. It can be considered that the directional light diffusion is inferior.
  • the anisotropic light diffusion film obtained in Test Example 4-9 has a large anisotropy of tensile strength, so interfacial separation between the continuous phase (I) and the dispersed phase (II) is likely to occur, and the interfacial reflection is large and low. It can be said that the reflectivity is inferior. Moreover, since the refractive index difference between the continuous phase (I) and the dispersed phase (II) is very small, it can be said that the anisotropic light diffusibility is inferior.
  • the dispersion diameter in the TD direction and the thickness direction is small, so that the reflection per dispersed phase is large, and the present light diffusion
  • An ideal island component with strong diffusivity could not be formed in the vicinity of the direction inclined 60° from the normal N direction of the film surface to the light diffusion direction, which was different from Test Examples 4-1 to 4-6. It can be considered that the directional light diffusion is inferior.
  • this light diffusion film has excellent brightness and visibility when mounted on a display, it is particularly useful for image display devices such as personal computers, televisions, mobile terminals (PDA), mobile phones, smartphones, transparent screens, and LED diffusion plates. And it can be used as a component (diffusion member) such as a head-up display.

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Abstract

Un film de diffusion de lumière anisotrope selon un aspect de la présente invention comprend au moins une première couche capable de diffuser une lumière incidente dans la direction de déplacement de la lumière, et le rapport (rapport de luminosité de 60°/ rapport de luminosité avant) entre un rapport de luminosité de 60° et un rapport de luminosité avant qui sont obtenus par les procédés suivants est de 0,30 à 0,60 inclus.　<60° brightness ratio> Dans le film de diffusion de lumière, le rapport (C/B) entre une luminosité C dans une direction inclinée à 60° dans une direction de diffusion de lumière à partir de la direction d'une N normale à une surface de film et une luminosité avant B dans la direction de la normale N à la surface de film est définie comme étant le rapport de luminosité de 60°.　<Front brightness ratio> Le rapport (B/A) entre la luminosité avant B du film de diffusion de lumière et une luminosité avant A dans la direction d'une N normale à une surface de film dans un échantillon d'ébauche satisfaisant aux conditions (1) et (2) est défini comme étant le rapport de luminosité avant.　[Échantillon blanc] Condition (1) : La transmittance de lumière totale mesurée conformément à JIS K7361-1 est de 90 % ou plus.　Condition (2) : Le trouble mesuré conformément à JIS K7136 est de 1 % ou moins.
PCT/JP2022/040850 2021-11-02 2022-11-01 Film de diffusion de lumière anisotrope, film de diffusion de lumière anisotrope avec couche adhésive, et dispositif d'affichage d'image WO2023080130A1 (fr)

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JP2021179414A JP2023068370A (ja) 2021-11-02 2021-11-02 異方性光拡散フィルム及びこれを備えてなる液晶表示装置
JP2021-179414 2021-11-02
JP2021-212117 2021-12-27
JP2021-212116 2021-12-27
JP2021212116A JP2023096394A (ja) 2021-12-27 2021-12-27 異方性光拡散フィルム、粘着剤層付き異方性光拡散フィルム及び画像表示装置
JP2021212117A JP2023096395A (ja) 2021-12-27 2021-12-27 異方性光拡散フィルム、粘着剤層付き異方性光拡散フィルム及び画像表示装置
JP2022-043572 2022-03-18
JP2022043572 2022-03-18
JP2022043574 2022-03-18
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JP2022-043573 2022-03-18
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Publication number Priority date Publication date Assignee Title
JP2001159704A (ja) * 1999-09-21 2001-06-12 Daicel Chem Ind Ltd 異方性光散乱フィルム
JP2002001858A (ja) * 2000-06-22 2002-01-08 Daicel Chem Ind Ltd 積層フィルム
JP2003050306A (ja) * 2001-06-01 2003-02-21 Daicel Chem Ind Ltd 異方性拡散フィルム
JP2003075643A (ja) * 2001-06-22 2003-03-12 Daicel Chem Ind Ltd 偏光素子並びにそれを用いた面光源装置及び液晶表示装置
JP2008241889A (ja) * 2007-03-26 2008-10-09 Sekisui Chem Co Ltd プリズムシート及び光学シート
JP2009157029A (ja) * 2007-12-26 2009-07-16 Hitachi Maxell Ltd レンズシート、レンズシートを用いたバックライト及び液晶表示装置
JP2009277553A (ja) * 2008-05-15 2009-11-26 Hitachi Maxell Ltd バックライト、光学部材、レンチキュラレンズシート及び液晶表示装置
JP2014038171A (ja) * 2012-08-14 2014-02-27 Daicel Corp 異方性光拡散積層体及びプロジェクタースクリーン
JP2014535127A (ja) * 2011-09-30 2014-12-25 コーニンクレッカ フィリップス エヌ ヴェ ディスプレイバックライトシステム
WO2015030036A1 (fr) * 2013-08-28 2015-03-05 富士フイルム株式会社 Élément de conversion de lumière, unité de rétroéclairage le contenant et dispositif d'affichage à cristaux liquides

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001159704A (ja) * 1999-09-21 2001-06-12 Daicel Chem Ind Ltd 異方性光散乱フィルム
JP2002001858A (ja) * 2000-06-22 2002-01-08 Daicel Chem Ind Ltd 積層フィルム
JP2003050306A (ja) * 2001-06-01 2003-02-21 Daicel Chem Ind Ltd 異方性拡散フィルム
JP2003075643A (ja) * 2001-06-22 2003-03-12 Daicel Chem Ind Ltd 偏光素子並びにそれを用いた面光源装置及び液晶表示装置
JP2008241889A (ja) * 2007-03-26 2008-10-09 Sekisui Chem Co Ltd プリズムシート及び光学シート
JP2009157029A (ja) * 2007-12-26 2009-07-16 Hitachi Maxell Ltd レンズシート、レンズシートを用いたバックライト及び液晶表示装置
JP2009277553A (ja) * 2008-05-15 2009-11-26 Hitachi Maxell Ltd バックライト、光学部材、レンチキュラレンズシート及び液晶表示装置
JP2014535127A (ja) * 2011-09-30 2014-12-25 コーニンクレッカ フィリップス エヌ ヴェ ディスプレイバックライトシステム
JP2014038171A (ja) * 2012-08-14 2014-02-27 Daicel Corp 異方性光拡散積層体及びプロジェクタースクリーン
WO2015030036A1 (fr) * 2013-08-28 2015-03-05 富士フイルム株式会社 Élément de conversion de lumière, unité de rétroéclairage le contenant et dispositif d'affichage à cristaux liquides

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