WO2021079804A1

WO2021079804A1 - Light-diffusing film, and polarizing plate comprising light-diffusing film

Info

Publication number: WO2021079804A1
Application number: PCT/JP2020/038794
Authority: WO
Inventors: 貴博吉川; 聡司三田; 夏紀村上
Original assignee: 日東電工株式会社
Priority date: 2019-10-24
Filing date: 2020-10-14
Publication date: 2021-04-29
Also published as: CN114600008A; JP2021067849A; JP7446766B2; TW202119107A; KR20220084269A

Abstract

Provided is a light-diffusing film that, when combined with another film to constitute an optical laminate, can contribute to the durability (particularly high-humidity resistance) of the optical laminate.　This light-diffusing film comprises a shaping layer and a light-diffusing layer positioned on one surface of the shaping layer, the shaping layer including a base-material part and a relief part positioned on one surface of the base-material part, and the light-diffusing layer being positioned on the base-material-part side of the shaping layer.

Description

Polarizing plate with light diffusing film and light diffusing film

The present invention relates to a light diffusing film and a polarizing plate including a light diffusing film.

In recent years, there has been an increasing demand for thinner image display devices (for example, liquid crystal display devices and organic EL display devices) and improved design (for example, narrower bezels). Along with this, there is an increasing demand for integration of optical members and / or optical films used in image display devices and / or integration of functions. As an example of such integration or integration of functions, it has been proposed to directly attach a light diffusing film to a predetermined optical member or the like to impart a light diffusing function. The light diffusing film may be required to have excellent optical properties and workability, and the durability (particularly, humidification durability) of the optical laminate provided with the light diffusing film. It is difficult to satisfy these characteristics in a well-balanced manner in a diffusion film. In particular, it is difficult to stably produce a light diffusing film composed of light diffusing particles due to frequent breakage during film formation, and the processability and other characteristics (for example, optical characteristics) are deteriorated. It was difficult to achieve both.

Japanese Unexamined Patent Publication No. 2012-118235 Japanese Unexamined Patent Publication No. 2009-025774

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to have excellent processability and optical properties, and to form an optical laminate in combination with another film. An object of the present invention is to provide a light diffusing film that can contribute to the durability (particularly, humidification durability) of the optical laminate.

The light diffusing film of the present invention includes a shaping layer and a light diffusing layer arranged on one side of the shaping layer, and the shaping layer is arranged on a base material portion and one side of the base material portion. The light diffusing layer is arranged on the base material side of the shaping layer, including the uneven portion.
In one embodiment, the light diffusing layer and the shaping layer are laminated via an adhesive layer or an adhesive layer.
In one embodiment, the light diffusing layer is formed directly on the shaping layer.
In one embodiment, the light diffusing layer contains light diffusing particles, and the volume average particle diameter of the light diffusing fine particles is 2 μm to 30 μm or less.
In one embodiment, the light diffusing film has a haze value of 30% to 95%.
According to another aspect of the present invention, a polarizing plate is applied. The polarizing plate includes a polarizing element and the light diffusing film laminated with the polarizing element via an adhesive layer.

According to the present invention, by providing a shaping layer having uneven portions and a light diffusing layer, it has excellent processability and optical characteristics, and when an optical laminate is formed in combination with another film, it is formed. , A light diffusing film that can contribute to the durability (particularly, humidification durability) of the optical laminate can be provided.

It is the schematic sectional drawing of the light diffusion film by one Embodiment of this invention. It is a schematic plan view which shows the typical example of the plan view shape of the convex part of the concavo-convex surface in the light diffusion film by embodiment of this invention. It is the schematic sectional drawing of the optical laminated body by one Embodiment of this invention. It is the schematic sectional drawing of the polarizing plate by one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. The drawings are schematically shown for easy viewing, and the ratios of length, width and thickness, the shape and fineness of the unevenness, etc. are different from the actual ones.

A. Light diffusion film A-1. Overall Configuration FIG. 1 is a schematic cross-sectional view of a light diffusing film according to one embodiment of the present invention. The light diffusing film 100 of the illustrated example includes a shaping layer 10 and a light diffusing layer 20 arranged on one side of the shaping layer 10. The shaping layer 10 has a base material portion 11 and an uneven portion 12 formed on one surface of the base material portion 11. The uneven portion 12 has a convex portion 12a and a concave portion 12b. The light diffusion layer 20 is arranged on the base material portion 11 side (opposite side of the uneven portion 12) of the shaping layer 10. In one embodiment, the light diffusing film of the present invention is used by attaching the uneven portion 12 to another film.

FIG. 2 is a schematic plan view showing a typical example of the plan view shape of the convex portion of the uneven portion in the shaping layer of the light diffusion film according to one embodiment of the present invention. In one embodiment, as shown in FIG. 2, the recess 12b may have a cell structure formed surrounded by a convex portion 12a (substantially a wall surface of the convex portion). By forming the recess having the cell structure, when the light diffusing film is laminated on another film to form an optical laminate, it is possible to prevent moisture from entering the optical laminate. Further, by forming the recess having the cell structure, it is possible to obtain a light diffusion film capable of cutting with good workability by preventing defects such as cracking and chipping in the cut portion. It should be noted that not all of the recesses need to have a cell structure. For example, in the vicinity of the edge of the light diffusing film, the recess may be open on the edge side of the light diffusing film.

Any appropriate shape can be adopted as the plan view shape of the convex portion 12a in the concave-convex portion. The plan view shape of the convex portion 12a may be a regular shape (for example, a grid shape) or an irregular shape, as shown in FIG. 2, for example. The pitch of the convex portions (distance between the convex portions) is preferably 1000 μm or less, more preferably 500 μm or less, and further preferably 100 μm or less. If the plan view shape of the convex portion has regularity, the angle may be biased by 1 degree to 90 degrees. When the shape of the convex portion in a plan view is irregular, the pitch means an average pitch, and it is preferable that the distribution is such that within ± 50% of the average value of the pitch is 50% or more. With such a configuration, when the light diffusing film is laminated on another film, the adhesive strength between the light diffusing film and the other film can be ensured, and good display quality can be ensured. Further, when the light diffusing film is laminated on another film to form an optical laminate, it is possible to prevent moisture from entering the optical laminate.

In the present invention, by providing the shaping layer having the uneven portion, when the light diffusing film is laminated on another film to form an optical laminate, the convex portion (substantially convex) of the light diffusing film is formed. Only the top of the part) can be glued to another film. In this specification, bonding of only the convex portion may be referred to as "point bonding" for convenience. By such point bonding, a substantially low refractive index portion due to a recess (air portion or void portion) is defined in the vicinity of the point bonding portion. As a result, good light diffusion performance can be realized and the brightness viewing angle can be increased. Conventionally, another film (for example, a polarizing plate (polarizing plate)) and a light diffusing film are separately placed in an image display device, and as a result, an air layer is interposed between the polarizing plate and the light diffusing film. .. While the air layer becomes an obstacle to thinning, the brightness viewing angle is maintained large by the retroreflection by the air layer. By integrating another film and the light diffusing film, it is possible to reduce the thickness and integrate the functions, but the elimination of the air layer reduces the luminance viewing angle. By forming the low refractive index portion in the vicinity of the point-bonded portion, light is efficiently retroreflected as in the case where the air layer is present. Therefore, according to the embodiment of the present invention, by forming the point adhesion, the desired light diffusion performance can be exhibited and the luminance viewing angle can be maintained large (wide).

In one embodiment, the shaping layer does not contain light diffusing particles. The shaping layer can be produced by any suitable film forming method, but the shaping layer formed without containing light diffusing particles is less likely to break during film forming and is excellent in processability. It is the present invention that good light diffusing performance can be realized and the luminance viewing angle can be increased without containing light diffusing particles in the shaping layer (that is, while having good processability). This is one of the results.

The thickness of the light diffusing film of the present invention is preferably 25 μm to 250 μm, more preferably 30 μm to 100 μm.

The haze value of the light diffusing film of the present invention is preferably 30% to 95%, more preferably 40% to 93%, and even more preferably 60% to 90%. According to the present invention, it is possible to provide a light diffusing film capable of achieving an excellent luminance viewing angle while suppressing a decrease in luminance while increasing the haze value.

A-2. Shaped layer As the resin constituting the shaped layer, any suitable resin can be adopted. Specific examples of the resin constituting the shaping layer include (meth) acrylic resin, polyester resin (for example, polyethylene terephthalate (PET)), cycloolefin resin (for example, norbornene resin), and cellulose resin (for example). , Triacetyl cellulose (TAC)), polyvinyl alcohol-based resin, polycarbonate-based resin, polyamide-based resin, polyimide-based resin, polyether sulfone-based resin, polysulfone-based resin, polystyrene-based resin, polyolefin-based resin, acetate-based resin. .. These resins may be used alone or in combination of two or more. From the viewpoint of optical properties, transparency and versatility, (meth) acrylic resin, polyester resin and cycloolefin resin are preferable, and (meth) acrylic resin is more preferable. In addition, in this specification, "(meth) acrylic" means acrylic and / or methacryl.

As the (meth) acrylic resin, any suitable (meth) acrylic resin can be adopted. For the sake of simplification of the description, the (meth) acrylic resin is hereinafter simply referred to as an acrylic resin. Acrylic resins typically contain an alkyl (meth) acrylate as a main component as a monomer unit. Examples of the alkyl (meth) acrylate constituting the main skeleton of the acrylic resin include linear or branched alkyl groups having 1 to 18 carbon atoms. These can be used alone or in combination. Further, any suitable copolymerization monomer may be introduced into the acrylic resin by copolymerization. The type, number, copolymerization ratio, etc. of such copolymerization monomers can be appropriately set according to the purpose. The constituent components (monomer unit) of the main skeleton of the acrylic resin will be described later with reference to the general formula (2).

The acrylic resin preferably has at least one selected from a glutarimide unit, a lactone ring unit, a maleic anhydride unit, a maleimide unit, and a glutaric anhydride unit. Acrylic resins having a lactone ring unit are described in, for example, Japanese Patent Application Laid-Open No. 2008-181078, and the description in this publication is incorporated herein by reference. The glutarimide unit is preferably represented by the following general formula (1):

In the general formula (1), R ¹ and R ² independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 18 carbon atoms and 3 to 12 carbon atoms. The cycloalkyl group of the above, or an aryl group having 6 to 10 carbon atoms is shown. In the general formula (1), preferably R ¹ and R ² are independently hydrogen or methyl groups, and R ³ is a hydrogen, methyl group, butyl group or cyclohexyl group, respectively. More preferably, R ¹ is a methyl group, R ² is hydrogen and R ³ is a methyl group.

The above alkyl (meth) acrylate is typically represented by the following general formula (2):

In the general formula (2), R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ represents a hydrogen atom or an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms which may be substituted. Shown. Examples of the substituent include halogens and hydroxyl groups. Specific examples of alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and t-butyl (meth) acrylate. Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylate Included are 3-hydroxypropyl, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylic acid and 2,3,4,5-tetrahydroxypentyl (meth) acrylic acid. In formula (2), R ⁵ is preferably a hydrogen atom or a methyl group. Therefore, a particularly preferred alkyl (meth) acrylate is methyl acrylate or methyl methacrylate.

The acrylic resins may also include only a single glutarimide units, R ^1, R ² and R ³ may contain a plurality of different glutarimide units in formula (1).

The content ratio of the glutarimide unit in the acrylic resin is preferably 2 mol% to 50 mol%, more preferably 2 mol% to 45 mol%, further preferably 2 mol% to 40 mol%, and particularly preferably 2 mol. % To 35 mol%, most preferably 3 mol% to 30 mol%. If the content ratio is less than 2 mol%, the effects exhibited from the glutarimide unit (for example, high optical properties, high mechanical strength, thinning) may not be sufficiently exhibited. If the content ratio exceeds 50 mol%, for example, heat resistance and transparency may be insufficient.

The acrylic resins may also include only a single alkyl (meth) acrylate units, R ⁴ and R ⁵ in the above general formula (2) is comprise a plurality of different alkyl (meth) acrylate unit May be good.

The content ratio of the alkyl (meth) acrylate unit in the acrylic resin is preferably 50 mol% to 98 mol%, more preferably 55 mol% to 98 mol%, still more preferably 60 mol% to 98 mol%, and particularly preferably. Is 65 mol% to 98 mol%, most preferably 70 mol% to 97 mol%. If the content ratio is less than 50 mol%, the effects expressed from the alkyl (meth) acrylate units (for example, high heat resistance and high transparency) may not be sufficiently exhibited. If the content ratio is more than 98 mol%, the resin is brittle and easily cracked, high mechanical strength cannot be sufficiently exhibited, and productivity may be inferior.

The acrylic resin may contain units other than the glutarimide unit and the alkyl (meth) acrylate unit.

In one embodiment, the acrylic resin can contain, for example, 0% by weight to 10% by weight of unsaturated carboxylic acid units that are not involved in the intramolecular imidization reaction described later. The content ratio of the unsaturated carboxylic acid unit is preferably 0% by weight to 5% by weight, and more preferably 0% by weight to 1% by weight. When the content is in such a range, transparency, retention stability and moisture resistance can be maintained.

In one embodiment, the acrylic resin can contain a copolymerizable vinyl-based monomer unit (another vinyl-based monomer unit) other than the above. Examples of other vinyl-based monomers include acrylonitrile, methacrylonitrile, etacrylonitrile, allyl glycidyl ether, maleic anhydride, itaconic anhydride, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, and acrylic. Aminoethyl acid, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, metaallylamine, N-methylallylamine, 2 -Isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acroyl-oxazoline, N-phenylmaleimide, phenylaminoethyl methacrylate, styrene, α-methylstyrene, p-glycidylstyrene, p-aminostyrene, 2-styryl- Examples include oxazoline. These may be used alone or in combination. Styrene-based monomers such as styrene and α-methylstyrene are preferable. The content ratio of the other vinyl-based monomer unit is preferably 0 to 1% by weight, more preferably 0 to 0.1% by weight. Within such a range, the appearance of an undesired phase difference and the decrease in transparency can be suppressed.

The imidization ratio of the acrylic resin is preferably 2.5% to 20.0%. When the imidization ratio is within such a range, a resin having excellent heat resistance, transparency and molding processability can be obtained, and the generation of kogation during film molding and the decrease in mechanical strength can be prevented. In the acrylic resin, the imidization ratio is represented by the ratio of the glutarimide unit and the alkyl (meth) acrylate unit. This ratio can be obtained from, for example, an NMR spectrum, an IR spectrum, or the like of an acrylic resin. In this embodiment, the imidization rate ^{can be determined by 1 1} H-NMR measurement of the ^{resin using 1 1} HNMR BRUKER Avance III (400 MHz). More specifically, let A be the peak area derived from the _{O-CH 3} proton of the alkyl (meth) acrylate around 3.5 to 3.8 ppm _{, and N-CH 3 of glutarimide around 3.0 to 3.3 ppm.} It is calculated by the following equation, where B is the area of the peak derived from the proton.
Imidization rate Im (%) = {B / (A + B)} × 100

The acrylic resin has a Tg (glass transition temperature) of preferably 110 ° C. or higher, more preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and most preferably 130 ° C. or higher. When the Tg is 110 ° C. or higher, the polarizing plate containing the light diffusing film obtained from such a resin tends to have excellent durability. The upper limit of Tg is preferably 300 ° C. or lower, more preferably 290 ° C. or lower, still more preferably 285 ° C. or lower, particularly preferably 200 ° C. or lower, and most preferably 160 ° C. or lower. When Tg is in such a range, moldability can be excellent.

The acrylic resin can be produced, for example, by the following method. In this method, (I) an alkyl (meth) acrylate monomer corresponding to an alkyl (meth) acrylate unit represented by the general formula (2), an unsaturated carboxylic acid monomer and / or a precursor thereof is used alone. The body and the copolymer are copolymerized to obtain the copolymer (a); and (II) the copolymer (a) is treated with an imidizing agent to obtain the copolymer (a) in the copolymer (a). The alkyl (meth) acrylate monomer unit and the unsaturated carboxylic acid monomer and / or its precursor monomer unit are subjected to an intramolecular imidization reaction, and the glutarimide unit represented by the general formula (1) is copolymerized. Introducing into the polymer;

Details of the acrylic resin and the method for producing the same are described in, for example, JP-A-2018-155812 and JP-A-2018-155813. The description of these publications is incorporated herein by reference.

The height H of the convex portion 12a is preferably 5% to 40% with respect to the thickness of the shaping layer. Within such a range, good point adhesion can be realized. Further, setting the height of the convex portion within the above range is also advantageous from the viewpoint of mechanical strength, whereby the concave shape is preferably maintained, and excellent light diffusivity and a luminance viewing angle can be obtained.

The height H of the convex portion 12a is more preferably 10% to 30% and further preferably 10% to 20% with respect to the thickness of the shaping layer. Within such a range, good point adhesion can be realized.

The height H of the convex portion 12a is preferably 2.5 μm to 25 μm, and more preferably 5 μm to 20 μm. Within such a range, good point adhesion can be realized.

The average area of the recesses having a cell structure is preferably 5000 μm ² or more. Within such a range, it is possible to obtain a light diffusing film capable of realizing an excellent brightness viewing angle while suppressing a decrease in brightness. Average area of the recesses having a cell structure is more preferably 5000 .mu.m ² ~ 50000 ^2, more preferably from 7000μm ^² ~ 40000μm ^2, particularly preferably 8000μm ^² ~ 30000μm ^2. Within such a range, the above effect becomes remarkable, and a light diffusing film having excellent mechanical strength can be obtained. The average area of the recess having the cell structure can be obtained by using image analysis software (free software "ImageJ"). That is, the inside and outside of the recess are determined by the threshold value of the binary image on the surface of the shaped film, and the outer frame of the recess is specified. It can be obtained by calculating the area within the specified frame and calculating the average value of the calculated areas.

In one embodiment, the maximum length of the recess having a cell structure in a plan view is preferably 300 μm or more, more preferably 400 μm or more, and further preferably 500 μm or more. Within such a range, even when the light diffusing film is cut and used, the light diffusing film effectively prevents moisture intrusion and improves the durability in the vicinity of the end portion of the optical laminate. be able to. The maximum length of the concave portion having the cell structure means the distance at the place where the distance between the wall surfaces of the convex portion forming the concave portion is the longest.

The area ratio of the concave portion to the total area when the uneven portion is viewed in a plan view is preferably 50% or more, preferably 60% or more, and more preferably 70% or more. The upper limit of the area ratio of the recesses can be, for example, 90%. When the area ratio of the recesses is within such a range, good diffusion performance is imparted to the light diffusing film while maintaining a wide brightness viewing angle, and adhesive strength is obtained when the light diffusing film is laminated on another film. Can be secured.

In the light diffusing film of the present invention, it is preferable that the wall surface of the convex portion 12a exists in a region within 500 μm from the edge of the light diffusing film. In the present invention, when the light diffusing film is laminated on another film to form an optical laminate, the convex portion 12a can prevent moisture from entering the optical laminate. By forming the wall surface of the convex portion 12a in a region within 500 μm from the edge of the light diffusing film, it is possible to effectively prevent moisture intrusion and improve the durability in the vicinity of the edge of the optical laminate. It is more preferable that the wall surface of the convex portion 12a is present in a region within 400 μm from the edge of the light diffusing film, and even more preferably the wall surface of the convex portion 12a is present in a region within 300 μm from the edge of the light diffusing film. .. Preferably, the wall surface of the convex portion 12a is present in the entire region within 500 μm (preferably within 400 μm, more preferably within 300 μm) from the edge of the light diffusing film.

The ratio B / A of the cross-sectional area B of the concave portion to the cross-sectional area A of the entire uneven portion is preferably 50% or more, more preferably more than 50%, still more preferably 60% or more, and particularly preferably. It is 70% or more. The upper limit of the ratio B / A can be, for example, 90%. When the ratio B / A is in such a range, good diffusion performance is imparted to the light diffusing film while maintaining a wide brightness viewing angle, and adhesive strength is obtained when the light diffusing film is laminated on another film. Can be secured. The cross-sectional area A of the entire uneven portion is the area of the portion surrounded by the line connecting the surface of the convex portion, the line connecting the bottom of the concave portion, and the vertical line at both ends of the film (for reference, of the relevant portion). The cross-sectional area B of the recesses surrounded by a broken line on the outside is the cross-sectional area of each recess 22 (the line connecting the wall line of the adjacent convex portion and the surface of the convex portion and the line connecting the bottom of the concave portion). The total area of the part surrounded by and.

The thickness of the shaping layer is preferably 25 μm to 250 μm, more preferably 40 μm to 100 μm.

The thickness of the base material portion is preferably 22.5 μm to 225 μm, and more preferably 30 μm to 90 μm.

The uneven portion (concave shape) can be formed by any suitable method. The uneven shape can be formed by, for example, a roughening method or a method of imparting unevenness with fine particles. Specific examples of the roughening method include embossing and sandblasting. The uneven portion (concave and convex shape) can be typically formed by shaping the surface of the melt-extruded film with an embossed roll.

In one embodiment, the base material portion and the uneven portion are made of the same material. Preferably, the base material portion and the uneven portion are integrally formed of the same material.

A-3. Light diffusing layer The light diffusing layer may be made of a light diffusing element, or may be made of a light diffusing adhesive or a light diffusing adhesive. The light diffusing element may have a structure having a fine concavo-convex structure on the surface (external diffusion type light diffusion layer), and may have a structure including a matrix and light diffusing fine particles dispersed in the matrix (internal diffusion type light). It may be a diffusion layer). Further, the light diffusing element contains an arbitrary appropriate group of a dispersion liquid (for example, a coating liquid for forming a light diffusing layer) containing a light diffusing cured layer (for example, a matrix resin, light diffusing fine particles, and an additive if necessary). It may be formed by coating on a material, curing and / or drying), or it may be a light diffusing film (for example, a commercially available film). The matrix of the light diffusing adhesive is composed of an adhesive, and the matrix of the light diffusing adhesive is composed of an adhesive. When the light diffusing layer is composed of a light diffusing adhesive or a light diffusing adhesive, any suitable side opposite to the shaping layer of the light diffusing layer is used to protect the surface of the light diffusing layer. A protective film may be arranged.

Details of the light diffusing element and the light diffusing adhesive are described in, for example, JP-A-2012-83741, JP-A-2012-83742, JP-A-2012-83743, JP-A-2012-83744, JP-A-2013- It is described in Japanese Patent Application Laid-Open No. 235259 and Japanese Patent Application Laid-Open No. 2014-224964. The description of these publications is incorporated herein by reference. Surface-concavo-convex light diffusing elements are well known in the art.

The light diffusion layer is arranged directly on the shaping layer, or is laminated with the shaping layer via the shaping layer and the pressure-sensitive adhesive layer or the adhesive layer. The directly placed shaping layer can be formed by coating. The light diffusing layer thus formed includes, for example, a light diffusing layer formed by applying the above-mentioned coating liquid for forming a light diffusing layer, a light diffusing adhesive, or a light diffusing adhesive. Layers and the like can be mentioned. Examples of the light diffusing layer arranged via the pressure-sensitive adhesive layer or the adhesive layer include a light diffusing film. The pressure-sensitive adhesive layer that attaches the shaping layer and the light diffusing layer contains any suitable pressure-sensitive adhesive. Examples of the pressure-sensitive adhesive include rubber-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, cellulose-based pressure-sensitive adhesives, and the like, and acrylic-based pressure-sensitive adhesives are preferable. The adhesive layer that attaches the shaping layer and the light diffusing layer contains any suitable adhesive. Examples of the adhesive include water-based adhesives (for example, vinyl alcohol-based adhesives) and curable adhesives (for example, active energy ray-curable adhesives or heat-curable adhesives).

The light diffusion performance of the light diffusion layer can be expressed by, for example, a haze value. The haze value of the light diffusion layer is preferably 20% to 90%, more preferably 30% to 87%, and even more preferably 40% to 85%. The haze value of the light diffusing layer can be controlled by adjusting the fine uneven structure of the surface, the constituent material of the matrix (adhesive), the constituent material of the light diffusing fine particles, the volume average particle size, the blending amount, and the like. it can.

The total light transmittance of the light diffusion layer is preferably 75% or more, more preferably 80% or more, and further preferably 85% or more.

The thickness of the light diffusion layer can be appropriately adjusted according to the configuration, desired light diffusion performance, and the like. Specifically, the thickness of the light diffusion layer is preferably 2 μm to 100 μm, and more preferably 5 μm to 30 μm.

In one embodiment, the light diffusing layer is composed of a light diffusing adhesive. The light diffusing pressure-sensitive adhesive typically includes a pressure-sensitive adhesive as a matrix and light-diffusing fine particles dispersed in the pressure-sensitive adhesive.

Any appropriate adhesive can be used as the adhesive (matrix). Specific examples of the pressure-sensitive adhesive include rubber-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, cellulose-based pressure-sensitive adhesives, and the like, and acrylic-based pressure-sensitive adhesives are preferable. By using an acrylic pressure-sensitive adhesive, a light diffusion layer having excellent heat resistance and transparency can be obtained. The pressure-sensitive adhesive may be used alone or in combination of two or more.

Any suitable acrylic adhesive can be used. The glass transition temperature of the acrylic pressure-sensitive adhesive is preferably −60 ° C. to −10 ° C., more preferably −55 ° C. to −15 ° C. The weight average molecular weight of the acrylic pressure-sensitive adhesive is preferably 200,000 to 2 million, more preferably 250,000 to 1.8 million. By using an acrylic pressure-sensitive adhesive having such characteristics, appropriate pressure-sensitive adhesiveness can be obtained. The refractive index of the acrylic pressure-sensitive adhesive is preferably 1.40 to 1.65, and more preferably 1.45 to 1.60.

The acrylic pressure-sensitive adhesive is usually obtained by polymerizing a main monomer that imparts tackiness, a comonomer that imparts cohesiveness, and a functional group-containing monomer that serves as a cross-linking point while imparting tackiness. Acrylic adhesives having the above properties can be synthesized by any appropriate method. For example, they can be synthesized with reference to "Adhesive / Adhesive Chemistry and Applications" by Katsuhiko Nakamae published by Dainippon Tosho Co., Ltd.

The content of the pressure-sensitive adhesive in the light diffusion layer is preferably 50% by weight to 99.7% by weight, more preferably 52% by weight to 97% by weight.

Any suitable light diffusing fine particles can be used. Specific examples of the light diffusing fine particles include inorganic fine particles and polymer fine particles. The light diffusing fine particles are preferably polymer fine particles. Examples of the material of the polymer fine particles include polystyrene resin, polyurethane resin, melamine resin, silicone resin, acrylic resin, and styrene-acrylic copolymer resin. Since these resins have a desired difference in refractive index with respect to the pressure-sensitive adhesive and have excellent dispersibility with respect to the pressure-sensitive adhesive, a light-diffusing layer having excellent light-diffusing performance can be obtained. Preferably, it is a polystyrene resin. The shape of the light diffusing fine particles can be, for example, a true spherical shape, a flat shape, or an indefinite shape. The light diffusing fine particles may be used alone or in combination of two or more.

The volume average particle diameter of the light diffusing fine particles is preferably larger than 1 μm and 30 μm or less, more preferably 2 μm to 30 μm, further preferably 2 μm to 25 μm, and particularly preferably 3 μm to 20 μm. By setting the volume average particle diameter in the above range, a light diffusion layer having excellent optical characteristics can be obtained. In particular, if light diffusing fine particles having a volume average particle diameter of 2 μm or more are used, a light diffusing layer having remarkably excellent optical characteristics such as prevention of coloring of transmitted light can be obtained. The volume average particle size can be measured using an ultracentrifugal automatic particle size distribution measuring device.

The refractive index of the light diffusing fine particles is preferably 1.50 or more, more preferably 1.55 to 1.70, and further preferably 1.58 to 1.65.

The absolute value of the difference in refractive index between the light diffusing fine particles and the pressure-sensitive adhesive (matrix) is preferably 0.05 or more, more preferably 0.07 to 0.15, and further preferably 0.10 to 0. It is .13.

The content of the light diffusing fine particles in the light diffusing layer is preferably 0.3% by weight to 50% by weight, more preferably 3% by weight to 48% by weight. By setting the blending amount of the light diffusing fine particles within the above range, a light diffusing layer having excellent light diffusing performance can be obtained.

The light diffusing layer may contain any suitable additive. Examples of the additive include an antistatic agent and an antioxidant.

In another embodiment, the light diffusing layer is composed of a light diffusing element. In this case, the light diffusing layer typically includes a matrix and light diffusing fine particles dispersed in the matrix. The matrix is composed of, for example, an ionizing wire curable resin. Examples of the ionized wire include ultraviolet rays, visible light, infrared rays, and electron beams. It is preferably UV light, and therefore the matrix is preferably composed of UV curable resin. Examples of the ultraviolet curable resin include acrylic resins, aliphatic (for example, polyolefin) resins, and urethane resins. As the light diffusing fine particles, the same fine particles as the light diffusing fine particles that can be used for the light diffusing pressure-sensitive adhesive can be used. In this embodiment, the matrix may contain a resin component and an ultrafine particle component. In this case, a refractive index modulation region in which the refractive index changes substantially continuously can be formed outside the vicinity of the surface of the light diffusing fine particles. The refractive index modulation region is typically formed by a substantial gradient of the dispersion concentration of the ultrafine particle components in the matrix. By adopting such a configuration, backscattering can be suppressed. As described above, the resin component is preferably composed of an ultraviolet curable resin (for example, an acrylic resin). Specific examples of the monomer components constituting the acrylic resin include pentaerythritol triacrylate (PETA: molecular weight 298), neopentyl glycol diacrylate (NPGDA: molecular weight 212), dipentaerythritol hexaacrylate (DPHA: molecular weight 632), and di. Examples thereof include pentaerythritol pentaacrylate (DPPA: molecular weight 578) and trimethylolpropane triacrylate (TMPTA: molecular weight 296). The ultrafine particle component is preferably composed of an inorganic compound. Preferred inorganic compounds include, for example, metal oxides and metal fluorides. Specific examples of the metal oxide include zirconium oxide (zirconia) (refractive index: 2.19), aluminum oxide (refractive index: 1.56 to 2.62), and titanium oxide (refractive index: 2.49 to 2. 74), silicon oxide (refractive index: 1.25 to 1.46) can be mentioned. Specific examples of the metal fluoride include magnesium fluoride (refractive index: 1.37) and calcium fluoride (refractive index: 1.40 to 1.43). Details of the light diffusing layer (light diffusing element) including such a matrix are described in, for example, Japanese Patent Application Laid-Open No. 2010-250295 or Japanese Patent Application Laid-Open No. 2012-088692, and these descriptions are referred to in the present specification. It is used as.

B. Optical laminate B-1. Overall Configuration FIG. 3 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 200 of the illustrated example includes a light diffusing film 100 and another film 110 arranged on one side of the light diffusing film 100. The light diffusing film 100 and another film 110 are laminated so that the uneven portion 12 of the shaping layer 10 included in the light diffusing film 100 and another film 110 face each other. Typically, the light diffusing film 100 and another film 110 are laminated via the adhesive layer 120.

As described above, in the uneven portion 12 of the light diffusion film 100, the ratio B / A of the cross-sectional area B of the concave portion to the cross-sectional area A of the entire uneven portion is preferably 50% or more, more preferably more than 50%. It is more preferably 60% or more, and particularly preferably 70% or more. The upper limit of the ratio B / A can be, for example, 90%. The ratio B / A can correspond to the porosity. Within such a range, it is possible to obtain an optical laminate having good light diffusion performance, a large luminance viewing angle, and excellent mechanical strength.

B-2. Another film As another film, any suitable film can be adopted. Examples of another film include an optical film such as a polarizer, a wavelength conversion film, and a polarizing reflection film; glass (preferably thin glass); a resin film (for example, a protective film) and the like.

In one embodiment, a polarizer is used as another film. In this embodiment, the light diffusing film functions as a polarizer protective film, and the optical laminate can be a polarizing plate. Details of the polarizing plate will be described later.

B-3. Adhesive layer The adhesive layer is composed of any suitable adhesive or adhesive. The adhesive layer is typically formed of a water-based adhesive (eg, vinyl alcohol-based adhesive) or a curable adhesive (eg, active energy ray-curable adhesive or heat-curable adhesive).

In one embodiment, the adhesive layer contains an active energy ray-curable adhesive. If the adhesive layer is formed by using the active energy ray-curable adhesive, an optical laminate can be obtained without impairing the uneven shape of the light diffusing film.

As the active energy ray-curable adhesive, any suitable adhesive can be used as long as it is an adhesive that can be cured by irradiation with active energy rays. Examples of the active energy ray-curable adhesive include an ultraviolet curable adhesive and an electron beam-curable adhesive. Specific examples of the curing type of the active energy ray-curing adhesive include a radical curing type, a cation curing type, an anion curing type, and a combination thereof (for example, a hybrid of a radical curing type and a cation curing type).

The active energy ray-curable adhesive includes, for example, a compound (for example, a monomer and / or an oligomer) having a radically polymerizable group such as a (meth) acrylate group or a (meth) acrylamide group as a curing component. Can be mentioned.

Specific examples of the active energy ray-curable adhesive and a curing method thereof are described in, for example, Japanese Patent Application Laid-Open No. 2012-144690. This description is incorporated herein by reference.

As the method for applying the active energy ray-curable adhesive, any appropriate method can be adopted depending on the viscosity of the adhesive and the desired thickness of the adhesive layer or the like. Examples of the coating method include coating with a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, or the like. Further, the coating by the dipping method may be adopted.

Any appropriate method can be adopted as the curing method of the above-mentioned active energy ray-curable adhesive. Conditions such as the wavelength of the active energy ray and the irradiation amount can be set to any appropriate conditions according to the type of the curable compound used and the like.

The thickness of the portion where the thickness of the adhesive layer is maximum is preferably 0.5 μm to 10 μm, and more preferably 0.5 μm to 5 μm. Within such a range, it is possible to preferably form voids due to the unevenness of the shape film, and it is possible to obtain an optical laminate having excellent mechanical strength. In one embodiment, the portion where the thickness of the adhesive layer is maximized is from the upper surface of the convex portion of the light diffusing film (the surface facing another film) to the lower surface of another film (the surface facing the light diffusing film). Can correspond to the gap of. In another embodiment, the portion where the thickness of the adhesive layer is maximized can be a position corresponding to the recess of the light diffusing film (FIG. 4). For example, the adhesive layer may be formed so as to cover at least a part of the wall surface of the convex portion of the light diffusing film. At this time, the adhesive layer is not formed on the concave surface of the light diffusing film, and is preferably in a so-called meniscus shape. In this embodiment, it is possible to obtain an optical laminate having excellent adhesiveness between the light diffusing film and another film while securing voids.

In one embodiment, the thickness T of the adhesive layer formed on the upper surface of the convex portion of the light diffusion film is preferably thinner than the thickness (height) H of the convex portion. The ratio T / H of the thickness T to the height H of the convex portion is preferably 50% or less, more preferably 30% or less. When the ratio T / H is in such a range, good point adhesion can be realized. The lower limit of the ratio T / H can be, for example, 10%.

The light diffusing film has an uneven portion, and the convex portion of the light diffusing film and another film are bonded (that is, point-bonded) and laminated, but the adhesive layer is on another film. In addition to the portion that contributes to adhesion, it is preferable that the portion is also formed in the void portion. In other words, the adhesive layer preferably covers at least a part (preferably all) of another film surface in the recesses (void portions) of the light diffusing film. In this way, deterioration of another film can be prevented. Such an effect is particularly useful when another film is deteriorated by moisture, outside air, or the like, and is particularly useful when another film is a polarizer. The thickness of the adhesive layer in the void portion may be constant or indefinite. In one embodiment, the adhesive layer in the void portion has a meniscus shape and its thickness is indefinite. Examples of the method of providing the adhesive layer in the void portion include a method of forming an adhesive precursor layer on another film and then adhering the other film and the light diffusing film.

The storage elastic modulus of the adhesive layer at 25 ° C. is preferably 100 kPa or more, more preferably 100 kPa to 3 GPa, and even more preferably 100 kPa to 1 GPa. Within such a range, it is possible to preferably form voids due to the unevenness of the light diffusion film, and it is possible to obtain an optical laminate having excellent mechanical strength. The storage elastic modulus can be obtained by dynamic viscoelasticity measurement. For dynamic viscoelasticity measurement, for example, for a pressure-sensitive adhesive sample having a thickness of 2 mm and a diameter of 8 mm, "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific Co., Ltd. is used, and deformation mode: torsion, measurement frequency: 1 Hz, temperature rise rate 5 ° C / min, measurement temperature: −50 ° C to 150 ° C.

B-4. Polarizing plate As described above, in one embodiment, the optical laminate is a polarizing plate. FIG. 4 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. The polarizing plate 200a of the illustrated example includes a polarizing element 110a and a polarizer protective film 100a laminated on the polarizing element 110a via an adhesive layer 120. The polarizer protective film 100a in this embodiment corresponds to the above-mentioned light diffusing film. Further, the polarizer 110a corresponds to the above-mentioned other film. The polarizer protective film 100a is arranged so that the uneven portion side is the polarizer 110a side. The adhesive layer is as described above. Practically, another protective film 140 is arranged on the opposite side of the polarizing element protective film 100a. Practically, a pressure-sensitive adhesive layer 150 is further provided as the outermost layer, and the polarizing plate can be attached to the image display cell. A separator (not shown) is temporarily attached to the surface of the pressure-sensitive adhesive layer 150 so that it can be peeled off, protecting the pressure-sensitive adhesive layer until the polarizing plate is actually used, and enabling roll formation. The polarizing plate according to the embodiment of the present invention may be used as a backside polarizing plate of an image display device, or may be used as a viewing side polarizing plate. According to the embodiment of the present invention, since the polarizer protective film itself has a light diffusing performance and also serves as a light diffusing film, a remarkable reduction in thickness can be realized by a synergistic effect with the effect of eliminating the air layer.

Any suitable polarizer can be adopted as the polarizer. For example, the resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer system partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine or a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical properties, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is used.

The above-mentioned dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Alternatively, it may be stretched and then dyed. If necessary, the PVA-based film is subjected to a swelling treatment, a cross-linking treatment, a washing treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt and blocking inhibitor on the surface of the PVA-based film, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizer obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying the resin base material. It is produced by forming a PVA-based resin layer on the resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; and stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further include, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. The obtained resin base material / polarizer laminate may be used as it is (that is, the resin base material may be used as a protective layer for the polarizer), and the resin base material is peeled off from the resin base material / polarizer laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface. Details of the method for producing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The entire description of the publication is incorporated herein by reference.

The thickness of the polarizer is, for example, 1 μm to 80 μm. In one embodiment, the thickness of the polarizer is preferably 1 μm to 20 μm, more preferably 3 μm to 15 μm.

The polarizer protective film is preferably substantially optically isotropic. As used herein, the term "substantially optically isotropic" means that the in-plane phase difference Re (550) is 0 nm to 10 nm. The in-plane retardation Re (550) is more preferably 0 nm to 5 nm, further preferably 0 nm to 3 nm, and particularly preferably 0 nm to 2 nm. When the Re (550) of the polarizer protective film is in such a range, it is possible to prevent an adverse effect on the display characteristics when the polarizing plate containing the polarizer protective film is applied to an image display device. Re (550) is an in-plane phase difference of the film measured with light having a wavelength of 550 nm at 23 ° C. Re (550) is calculated by the formula: Re (550) = (nx-ny) × d. Here, nx is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), and ny is the in-plane direction orthogonal to the slow-phase axis (that is, the phase-advancing axis direction). It is the refractive index, and d is the thickness (nm) of the film.

The higher the light transmittance at 380 nm in the polarizing element protective film having a thickness of 40 μm, the more preferable. Specifically, the light transmittance is preferably 75% or more, more preferably 80% or more, and further preferably 85% or more. When the light transmittance is in such a range, desired optical characteristics can be ensured. The light transmittance can be measured, for example, by a method according to ASTM-D-1003.

The haze of the polarizer protective film is preferably 50% to 99%, more preferably 70% to 95%.

The polarizer protective film preferably has the following characteristics. When the light transmittance at 550 nm is 100%, the difference between the light transmittance at 450 nm and 650 nm and the light transmittance at 550 nm is preferably within ± 5%, more preferably within ± 2%, respectively. is there.

Regarding the luminance viewing angle of the polarizer protective film, the luminance half-value angle (angle at which the luminance becomes 50% of the front surface) is preferably 56 ° (28 ° on one side) or more, and more preferably 60 ° to 70 ° (30 on one side). ° to 35 °). Further, the angle at which the brightness is 25% of the front surface is preferably 90 ° (45 ° on one side) or more, and more preferably 96 ° to 120 ° (48 ° to 60 ° on one side). According to the embodiment of the present invention, it is possible to impart excellent diffusion performance to the polarizer protective film and maintain a wide luminance viewing angle.

_{The refractive index n F} of the polarizer protective film as a whole is preferably 1.3 to 1.8, and more preferably 1.4 to 1.6. When the refractive index of the polarizer protective film is in such a range, the difference in refractive index from the low refractive index portion defined by the point adhesion with the polarizer in the polarizing plate can be set in a desired range.

Moisture permeability of the polarizer protective film is preferably 300g ^/ m 2 · 24hr or less, more preferably 250g ^/ m 2 · 24hr or less, more preferably 200g ^/ m 2 · 24hr or less, particularly preferably 150g ^/ m 2 · 24hr , and most preferably not more than 100g ^/ m 2 · 24hr. When the moisture permeability of the polarizer protective film is within such a range, a polarizing plate having excellent durability and moisture resistance can be obtained.

C. Image display device The above polarizing plate can be applied to an image display device. Therefore, the present invention also includes an image display device using such a polarizing plate. Typical examples of the image display device include a liquid crystal display device and an organic electroluminescence (EL) display device. Since the image display device adopts a configuration well known in the industry, detailed description thereof will be omitted.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows. Unless otherwise specified, "parts" and "%" in the examples are based on weight.

(1) Workability (tear strength)
The tear strength of the shaping layer was determined by a method according to JIS K7128-1 using the Trouser tear method. Under constant temperature conditions (23 ° C., relative humidity 50%), the test piece was cut out to a predetermined size, a slit of 75 mm was inserted, and a tear test was performed at a speed of 200 mm / min. 20 mm at the start of tearing and 5 mm before the end of tearing were excluded, and it was calculated from the average value of the tear strength of the remaining 50 mm. The test was carried out at N = 5, and the average value was calculated.
When the tear strength was 0.5 N or less, it was judged as NG because there is a risk of breakage during film formation.

(2) Optical characteristics The content of the light-diffusing fine particles is adjusted so that the haze of the light-diffusing film is 80%, and the transmittance T (450) at a wavelength of 450 nm, the transmittance T (550) at a wavelength of 550 nm, and the wavelength. The transmittance T (650) at 650 nm was measured.
The case where the value of ((T450) -T (650)) / T (550) was within ± 0.5 was regarded as acceptable (◯). The accepted product was not colored by transmitted light and had excellent optical characteristics.

(3) Humidity Durability After applying an adhesive to the surface of the polarizer with 1 μm, the polarizer is bonded to the uneven surface of the light diffusing film (polarizer protective film) obtained in Examples and Comparative Examples. Then, UV irradiation was performed to cure the adhesive to obtain a polarizing plate composed of a shaping film (polarizer protective film) / adhesive layer / polarizer.
A shaping film (polarizer protective film) of the polarizing plate and a glass plate were laminated via an acrylic pressure-sensitive adhesive. The obtained laminate was left to stand in an environment of a temperature of 60 ° C. and a humidity of 90% for 500 hours. Then, the transmittance of the laminated body was measured by an absorptiometer with an integrating sphere (“V7100” manufactured by JASCO Corporation).
When the transmittance after heating and humidification changed by 10% or more with respect to the transmittance before heating and humidification, it was evaluated as rejected (x), and when the change was less than 10%, it was evaluated as acceptable (◯).

<Example 1>
A methacrylic resin (manufactured by Kuraray Co., Ltd., product name "Parapet HR-S") is put into a single-screw extruder, and while melt-extruded at 260 ° C., an embossed roll is used to shape an uneven shape on one surface to form a shaping layer. (Thickness: 50 μm, convex height: 10 μm, cell size: 15000 μm ² ) was obtained.
On the side of the shaping layer having no uneven shape, a mixture of 10 parts of silica particles having a volume average particle diameter of 10 μm was applied to an acrylic ultraviolet curable resin. The coating layer was irradiated with ultraviolet rays to cure the ultraviolet curable resin to form a light diffusing layer, and a light diffusing film was obtained.
The obtained light diffusion film was subjected to the above evaluations (1) to (3). The results are shown in Table 1.

<Example 2>
A light diffusion film was obtained in the same manner as in Example 1 except that silica particles having a volume average particle diameter of 6 μm were used as the silica particles in the light diffusion layer.
The obtained light diffusion film was subjected to the above evaluations (1) to (3). The results are shown in Table 1.

<Example 3>
A light diffusion film was obtained in the same manner as in Example 1 except that silica particles having a volume average particle diameter of 2 μm were used as the silica particles in the light diffusion layer.
The obtained light diffusion film was subjected to the above evaluations (1) to (3). The results are shown in Table 1.

<Example 4>
A shaping layer was obtained in the same manner as in Example 1.
On the side of the shaping layer that does not have an uneven shape, the shaping layer and the acrylic film are laminated via an adhesive film (light diffusion adhesive) in which silica particles are dispersed in an acrylic pressure-sensitive adhesive, and light is applied. A diffusion film was obtained.
The obtained light diffusion film was subjected to the above evaluations (1) to (3). The results are shown in Table 1.

<Example 5>
A shaping layer was obtained in the same manner as in Example 1.
On the side of the shaping layer that does not have an uneven shape, the shaping layer and a light diffusing film (manufactured by Kimoto Co., Ltd., trade name "diffusing film MXE") are laminated via an acrylic adhesive to diffuse light. I got a film. The light diffusing film was laminated with the surface opposite to the diffusing layer on the shaping layer side.
The obtained light diffusion film was subjected to the above evaluations (1) to (3). The results are shown in Table 1.

<Comparative example 1>
For 100 parts of methacrylic resin (manufactured by Kuraray, product name "Parapet HR-S"), 9 parts of silicone resin fine particles (volume average particle diameter 4.5 μm) as light diffusible fine particles are put into a single-screw extruder. Then, while melt-extruding at 260 ° C., an uneven shape was formed on one surface with an embossing roll to obtain a ^{light diffusing film (thickness: 50 μm, convex height: 10 μm, cell size: 15000 μm 2).}
The obtained light diffusion film was subjected to the above evaluations (1) to (3). The results are shown in Table 1.

<Comparative example 2>
A prism film BEF2-T-155 manufactured by 3M Ltd. was subjected to the above evaluation (3). At that time, an adhesive was applied to the surface of the polarizer with 1 μm, and then the prism film was bonded to the prism side.

The light diffusing film of the present invention can be used in various fields as a film capable of imparting a light diffusing function. For example, the light diffusing film of the present invention is preferably used as a polarizing plate. The polarizing plate of the present invention is suitably used for an image display device. The image display device of the present invention is a portable device such as a mobile information terminal (PDA), a smartphone, a mobile phone, a clock, a digital camera, or a portable game machine; an OA device such as a personal computer monitor, a laptop computer, or a copy machine; a video camera, a television. , Household electrical equipment such as microwave ovens; In-vehicle equipment such as back monitors, car navigation system monitors, car audio; Exhibition equipment such as digital signage and information monitors for commercial stores; Security equipment such as monitoring monitors; Nursing care It can be used for various purposes such as nursing / medical equipment such as monitors and medical monitors.

10 Shaped layer 11 Base material 12 Concavo-convex part 12a Convex part 12b Concave part 20 Light diffusing layer 100 Light diffusing film 110 Another film 120 Adhesive layer 200 Optical laminate

Claims

A shaping layer and a light diffusing layer arranged on one side of the shaping layer are provided.
The shaping layer includes a base material portion and an uneven portion arranged on one surface of the base material portion.
The light diffusing layer is arranged on the base material side of the shaping layer.
Light diffusion film.
The light diffusing film according to claim 1, wherein the light diffusing layer and the shaping layer are laminated via an adhesive layer or an adhesive layer.
The light diffusing film according to claim 1, wherein the light diffusing layer is directly formed on the shaping layer.
The light diffusing layer contains light diffusing particles and contains.
The volume average particle diameter of the light diffusing fine particles is 2 μm to 30 μm.
The light diffusing film according to any one of claims 1 to 3.
The light diffusing film according to any one of claims 1 to 4, wherein the haze value is 30% to 95%.
A polarizing plate comprising a polarizing element and a light diffusing film according to any one of claims 1 to 5, which is laminated with the polarizing element via an adhesive layer.