WO2011162184A1

WO2011162184A1 - Light-diffusing polarization plate and liquid-crystal display device

Info

Publication number: WO2011162184A1
Application number: PCT/JP2011/063952
Authority: WO
Inventors: 康弘羽場; 室　誠治
Original assignee: 住友化学株式会社
Priority date: 2010-06-24
Filing date: 2011-06-17
Publication date: 2011-12-29
Also published as: TW201213886A; JP2012008332A

Abstract

Disclosed is a polarization plate to which light-diffusion functionality is imparted via the provision of a light-diffusing layer. Said polarization plate has sufficient mechanical strength, and when incorporated into a liquid-crystal display device, can provide high-quality display. Also disclosed is a liquid-crystal display device using said polarization plate. The disclosed light-diffusing polarization plate (100) comprises a protective film (109), a polarizing film (101), a protective film (110), a light-diffusing adhesive layer (104), and a light-diffusing film (102), layered in that order. The light-diffusing polarization plate (100) exhibits a total haze value and an internal haze value that are both greater than 40% and no greater than 85%. The light-diffusing adhesive layer (104) exhibits a total haze value between 10% and 80%.

Description

Light diffusing polarizing plate and liquid crystal display device

The present invention relates to a light diffusing polarizing plate and a liquid crystal display device using the light diffusing polarizing plate.

In recent years, the use of liquid crystal display devices in mobile phones, monitors for personal computers, televisions, liquid crystal projectors, etc. is rapidly progressing. In general, a liquid crystal display device includes a backlight device, a liquid crystal panel including a liquid crystal cell, a back side polarizing plate disposed on the backlight side of the liquid crystal cell, and a front side polarizing plate disposed on the viewing side of the liquid crystal cell. , Including.

Conventionally, in a liquid crystal display device, when the display screen is viewed from an oblique direction, high contrast cannot be obtained, and further, good display characteristics cannot be obtained due to a gradation reversal phenomenon in which the contrast of the image is reversed. The problem, that is, the problem that the viewing angle is narrow has been pointed out.

As a method for solving the above problems, a technique of providing a light diffusion film on the viewing side surface of a liquid crystal display device is conventionally known. For example, in Japanese Patent Application Laid-Open No. 2007-94369 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2002-107512 (Patent Document 2), a coating liquid containing fine particles (light diffusing agent) is applied onto a substrate. A light diffusion film (light diffusion sheet) having a high-haze light diffusion layer to be formed is disclosed.

Further, for example, in Japanese Patent Application Laid-Open No. 2009-301014 (Patent Document 3), a liquid crystal display provided with a glare-proof layer having a certain level of light diffusibility on the viewing side by dispersing and mixing minute fillers (light diffusing agents). An apparatus is disclosed. By disposing such a light diffusing film or antiglare layer on the viewing side surface of the liquid crystal display device, when the display screen of the liquid crystal display device is observed from an oblique direction, image contrast deterioration and gradation inversion are improved. It is possible to widen the viewing angle.

JP 2007-94369 A JP 2002-107512 A JP 2009-301014 A

In the liquid crystal display device including the light diffusing layer imparted with the light diffusibility by the filler as described above, a wider viewing angle can be obtained by increasing the content of the filler in the light diffusing layer. However, the light diffusion layer containing a large amount of filler has a high surface roughness. If such a light diffusing layer is disposed on the surface of the display, it is not preferable because the display quality is lowered such as whitening due to reflection of outside light. Note that “whitening” is a phenomenon in which the surface of the screen of the liquid crystal display device looks whitish, and is a phenomenon that is likely to occur particularly in a bright place.

As a method of reducing the surface roughness of the light diffusion layer containing a large amount of filler, a method of increasing the thickness of the light diffusion layer, or forming a layer containing no filler or only a small amount outside the light diffusion layer However, it is not economically advantageous, and it may be difficult to meet the demand for thinning the entire liquid crystal display device. Further, when the light diffusing layer is thick, there is a disadvantage that the mechanical strength of the layer structure including the light diffusing layer is lowered and becomes difficult to handle.

Accordingly, an object of the present invention is a polarizing plate provided with a light diffusing function by providing a light diffusing layer, which has a sufficient mechanical strength and has a good image quality when incorporated in a liquid crystal display device. It is an object to provide a polarizing plate and a liquid crystal display device using the same.

The present invention is a light diffusing polarizing plate comprising a polarizing film (film), a light diffusing film, and a light diffusing pressure-sensitive adhesive layer, wherein the total haze of the light diffusing polarizing plate exceeds 40%. 85% or less, the internal haze of the light diffusable polarizing plate is more than 40% and 85% or less, and the total haze of the light diffusable pressure-sensitive adhesive layer is 10% or more and 80% or less. Provide a board.

In one form of the light diffusable polarizing plate of the present invention, the light diffusing pressure-sensitive adhesive layer further includes a pair of protective films laminated on both surfaces of the polarizing film, It is laminated on the surface opposite to the film side.

In one embodiment of the light diffusing polarizing plate of the present invention, the light diffusing pressure-sensitive adhesive layer is laminated on one surface of the light diffusing film.

In a preferred embodiment of the light diffusing polarizing plate of the present invention, the light diffusing polarizing plate further includes a pair of protective films laminated on both surfaces of the polarizing film, one of the protective films, the polarizing film, the other protective film, and the light. The diffusible pressure-sensitive adhesive layer and the light diffusion film are laminated in this order.

In one form of the light diffusing polarizing plate of the present invention, the laser light having a wavelength of 543.5 nm is incident on the light diffusing polarizing plate and is emitted after passing through the polarizing film and the light diffusing film in this order. The ratio L ₂ / L of the intensity L ₂ of the laser light emitted in a direction inclined by 40 ° from the normal direction with respect to the intensity L _{1 of the} laser light incident in the normal direction of the light diffusing polarizing plate ₁ is preferably 0.0002% or more and 0.01% or less.

In the present invention, a backlight device, a light diffusing means, a backlight side polarizing plate, a liquid crystal cell, and the light diffusing polarizing plate are arranged in this order, and are close to the liquid crystal cell. Provided is a liquid crystal display device in which the light diffusing polarizing plate is arranged so that the polarizing film and the light diffusing film are located in this order from the side.

In the liquid crystal display device of the present invention, the light emitted from the light diffusing means has a luminance in a direction inclined by 70 ° from the normal direction of the light diffusing means with respect to the luminance in the normal direction of the light diffusing means. %, And the emitted light preferably includes non-parallel light.

The light diffusion means includes, for example, a light diffusion plate and a light deflection plate, and the light diffusion plate and the light deflection plate are arranged in this order from the backlight device side.

As the liquid crystal cell, a TN (twisted nematic) liquid crystal cell, an IPS (in-plane switching) liquid crystal cell, a VA (vertical alignment) liquid crystal cell, or the like can be used.

According to the present invention, a polarizing plate provided with a light diffusing function by providing a light diffusing layer has sufficient mechanical strength, and displays a good image quality when incorporated in a liquid crystal display device. A polarizing plate can be provided. The liquid crystal display device of the present invention to which the light diffusing polarizing plate is applied can display a good image quality.

When laser light is incident from the normal direction of the incident surface of the light diffusing polarizing plate, and the transmitted scattered light intensity of the laser light transmitted in the direction inclined by 40 ° from the normal direction on the output surface is measured, It is the perspective view which showed typically the incident direction and the transmitted scattered light intensity | strength measurement direction. It is a schematic sectional drawing which shows 1st Embodiment of the light diffusable polarizing plate of this invention. It is the schematic which shows an example of the apparatus for manufacturing a light-diffusion film. It is a schematic sectional drawing which shows 2nd Embodiment of the light diffusable polarizing plate of this invention. It is a schematic sectional drawing which shows 3rd Embodiment of the light diffusable polarizing plate of this invention. It is a schematic sectional drawing which shows a preferable example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of a light-diffusion means. It is a schematic sectional drawing which shows another example of a light-diffusion means. It is a schematic perspective view for demonstrating the relationship between the ridgeline direction of the linear prism which two light deflection plates (prism sheet | seat) have, and the transmission-axis direction of a polarizing plate. It is an example of a method for measuring the luminance value in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell for the light diffusion means. It is a figure explaining the definition of non-parallel light. It is a schematic sectional drawing which shows another preferable example of the liquid crystal display device of this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following forms.
<Light diffusing polarizing plate>
The light diffusable polarizing plate according to the present invention includes a polarizing film, a light diffusing film, and a light diffusing pressure-sensitive adhesive layer. The total haze of the light diffusable polarizing plate is more than 40% and 85% or less, and the internal haze of the light diffusing polarizing plate is more than 40% and 85% or less. The light diffusable pressure-sensitive adhesive layer is laminated at any position of the polarizing plate. The total haze of the light diffusable pressure-sensitive adhesive layer is 10% or more and 80% or less. The light diffusable polarizing plate according to the present invention has one or a plurality of such light diffusable pressure-sensitive adhesive layers. ADVANTAGE OF THE INVENTION According to this invention, while having high light diffusibility, it can provide the light diffusable polarizing plate which is thin and easy to handle. The liquid crystal display device of the present invention to which the light diffusing polarizing plate is applied can display a good image quality.

[Optical characteristics of light-diffusing polarizing plate]
(1) Haze The total haze of the light diffusable polarizing plate of the present invention is more than 40% and 85% or less, and the internal haze is more than 40% and 85% or less. Here, “total haze” refers to the total light transmittance (Tt) that represents the total amount of light transmitted through the light diffusing polarizing plate, and the diffused light that has been diffused and transmitted by the light diffusing polarizing plate. From the ratio with the transmittance (Td), the following formula (1):
Total haze (%) = (Td / Tt) × 100 (1)
It is calculated by.

The total light transmittance (Tt) is the sum of the parallel light transmittance (Tp) and the diffuse light transmittance (Td) that are transmitted coaxially with the incident light. The total light transmittance (Tt) and the diffused light transmittance (Td) are values measured in accordance with JIS K 7361.

Further, the “internal haze” of the light diffusing polarizing plate is a haze other than the haze (surface haze) due to the surface shape of the light diffusing polarizing plate among all the hazes.

When the total haze and / or internal haze is 40% or less, the light scattering property is insufficient and the viewing angle may be narrowed. Further, when the total haze and / or internal haze exceeds 85%, light scattering is too strong. Therefore, when the light diffusing polarizing plate is applied to a liquid crystal display device, for example, in the black display, the front direction of the liquid crystal display device However, the front contrast is lowered due to the fact that light leaking obliquely is scattered in the front direction and the display quality is deteriorated.
Further, when the total haze and / or internal haze exceeds 85%, the transparency of the light diffusing polarizing plate tends to be impaired. The total haze and internal haze are each preferably 50% or more and 85% or less, and more preferably 59% or more and 77% or less.

The total haze, internal haze, and surface haze of the light diffusing polarizing plate are specifically measured as follows. The total haze is measured by using a haze transmittance meter in accordance with JIS K 7136 (for example, a haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd.) and total light transmittance (Tt) and diffuse light transmittance. (Td) is measured and calculated by the above formula (1).

Next, a triacetyl cellulose film having a haze of approximately 0% is bonded to the light exit surface of the light diffusing polarizing plate using glycerin, and the haze is measured in the same manner as the measurement of the total haze described above. The haze can be regarded as “internal haze” of the light diffusing film because it is almost canceled by the triacetyl cellulose film to which the surface haze resulting from the surface shape of the light diffusing polarizing plate is bonded. Therefore, the “surface haze” of the light diffusing polarizing plate is expressed by the following formula (2):
Surface haze (%) = Total haze (%)-Internal haze (%) (2)
More demanded.

The surface haze caused by the surface shape of the light diffusing polarizing plate is preferably 2% or less. When the surface haze exceeds 2%, whitening tends to occur due to surface irregular reflection. In order to prevent whitening more effectively, the surface haze is preferably 1% or less.

(2) Relative scattered light intensity The light diffusable polarizing plate of the present invention is incident on the light diffusing polarizing plate, and the laser light having a wavelength of 543.5 nm emitted after passing through the polarizing film and the light diffusing film in this order, Ratio L ₂ / L ₁ of the intensity L ₂ of the laser beam emitted in a direction inclined by 40 ° from the normal direction with respect to the intensity L _{1 of the} laser beam incident in the normal direction of the light diffusing polarizing plate ( Relative scattered light intensity) is preferably 0.0002% or more and 0.01% or less. Hereinafter, the relative scattered light intensity will be described with reference to FIG.

FIG. 1 is a perspective view schematically showing an incident direction of laser light and a transmitted scattered light intensity measurement direction in a light diffusing polarizing plate. Referring to FIG. 1, a laser beam (He having a wavelength of 543.5 nm and an intensity of L ₁ incident from the incident surface side of light diffusing polarizing plate 10 in the direction of normal A1 of light diffusing polarizing plate 10 is shown. for -Ne laser parallel light), obtained by measuring the polarizing film, the transmitted scattered light intensity L ₂ of the laser light passing through the light diffusion film in a direction A3 inclined 40 ° from the normal direction A2 after passing in this order The relative scattered light intensity L ₂ / L ₁ is preferably in the range of 0.0002% to 0.01%. More preferably, the relative scattered light intensity L ₂ / L ₁ is in the range of 0.0004% to 0.0014%.

When the relative scattered light intensity L ₂ / L ₁ is less than 0.0002%, the light scattering property is insufficient and the viewing angle becomes narrow. If it exceeds 0.01%, light scattering is too strong, so when a light diffusing polarizing plate is applied to a liquid crystal display device, for example, in black display, it leaks obliquely with respect to the front direction of the liquid crystal display device. The front contrast is lowered due to the fact that the emitted light is scattered in the front direction by the light diffusion layer, and the display quality is deteriorated. The relative scattered light intensity L ₂ / L ₁ is more preferably 0.0003% or more and 0.001% or less.

For measuring the relative scattered light intensity, an optical power meter (for example, “3292 03 optical power sensor” manufactured by Yokogawa Electric Corporation and “3292 optical power meter” manufactured by the same company) can be used.

[Haze of light diffusing adhesive layer]
The light diffusing pressure-sensitive adhesive layer is laminated at any position of the polarizing plate. The total haze of the light diffusable pressure-sensitive adhesive layer is 10% or more and 80% or less. Preferably, the total haze of the light diffusable pressure-sensitive adhesive layer is 25% or more and 70% or less. Since the light diffusing polarizing plate according to the present invention has a light diffusing pressure-sensitive adhesive layer, even if the light diffusing film does not have high diffusibility, the light diffusing polarizing plate as a whole achieves a desired haze. be able to. Therefore, sufficient light diffusibility can be ensured as a whole. That is, it is possible to provide a light diffusing polarizing plate having a desired haze while suppressing a reduction in display quality due to thinning of the light diffusing film and protrusion of the light diffusing agent from the surface. The total haze of the light diffusable pressure-sensitive adhesive layer can be measured by the same method as the total haze of the light diffusable polarizing plate.

[First embodiment]
FIG. 2 is a schematic cross-sectional view showing the light diffusable polarizing plate of the first embodiment. In FIG. 2, the light diffusing polarizing plate 100 has a polarizing film 101, and a first protective film 110, a diffusible adhesive layer 104, and a light diffusing film 102 are laminated in this order on one surface of the polarizing film 101. The second protective film 109 is laminated on the other surface of the polarizing film 101.

(Polarizing film)
As the polarizing film 101, for example, a film made of a polyvinyl alcohol resin, a polyvinyl acetate resin, an ethylene / vinyl acetate (EVA) resin, a polyamide resin, a polyester resin, etc., and a dichroic dye adsorbed and oriented, a molecule A polyvinyl alcohol / polyvinylene copolymer containing an oriented molecular chain of a dichroic dehydrated product of polyvinyl alcohol (polyvinylene) in a partially oriented polyvinyl alcohol film.
In particular, those obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin layer are preferably used.

As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with vinyl acetate.
Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol-based resin is preferably 98.0 mol% or more.
If the saponification degree is less than 98.0 mol%, sufficient optical performance may not be obtained.

The saponification degree as used herein is a unit ratio (mol%) representing the ratio of the acetate group contained in the polyvinyl acetate resin, which is a raw material for the polyvinyl alcohol resin, to a hydroxyl group by the saponification step. Is a numerical value defined by the following formula. It can be determined by the method defined in JIS K K 6726 (1994).

Saponification degree (mol%) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100
The higher the degree of saponification, the higher the proportion of hydroxyl groups, that is, the lower the proportion of acetate groups that inhibit crystallization. Further, the polyvinyl alcohol resin used in the present embodiment may be a modified polyvinyl alcohol partially modified. For example, polyvinyl alcohol-based resins modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, alkyl esters of unsaturated carboxylic acids, acrylamide, etc. . The average degree of polymerization of the polyvinyl alcohol resin is not particularly limited, but is preferably 100 to 10,000, and more preferably 1500 to 10,000.

Examples of the polyvinyl alcohol-based resin having such characteristics include PVA124H (degree of saponification: 99.9 mol% or more), PVA124 (degree of saponification: 98.0 to 99.0 mol%) manufactured by Kuraray Co., Ltd. PVA117H (degree of saponification: 99.3 mol% or more), PVA117 (degree of saponification: 98.0 to 99.0 mol%); for example, NH-18 (degree of saponification: Nippon Synthetic Chemical Industry Co., Ltd.) 98.0 to 99.0 mol%), N-300 (degree of saponification: 98.0 to 99.0 mol%); for example, JF-17 (degree of saponification: 98 manufactured by Nihon Acetate Bipoar Co., Ltd.) 0.0-99.0 mol%), JF-17L (degree of saponification: 98.0-99.0 mol%), JF-20 (degree of saponification: 98.0-99.0 mol%) and the like. And can be suitably used in this embodiment.

A film obtained by forming such a polyvinyl alcohol-based resin constitutes the polarizing film 101 according to the present embodiment. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The polarizing film 101 is preferably uniaxially stretched at a stretch ratio of more than 5 times, more preferably more than 5 times and not more than 17 times.

The thickness of the polarizing film 101 is not particularly limited, but is generally preferably 100 μm or less, more preferably in the range of 10 to 50 μm, and still more preferably in the range of 25 to 35 μm from the viewpoint of thinning the polarizing plate.

(Light diffusion film)
The light diffusion film 102 includes a base film 105 and a light diffusion layer 106 laminated on the base film 105. The light diffusing layer 106 is a layer having a translucent resin 106b as a base material, and the light diffusing agent 106a is dispersed in the translucent resin 106b. As shown in FIG. 2, the light diffusing film 106 may have a light diffusing layer 702 whose surface is constituted by an uneven surface or a flat surface. Note that another layer (including an adhesive layer) may be provided between the base film 105 and the light diffusion layer 106.

(1) Base film The base film 105 of the light diffusing film 102 may be a light-transmitting film, and for example, glass or plastic film can be used. The plastic film only needs to have appropriate transparency and mechanical strength. Specific examples include cellulose acetate resins such as TAC (triacetyl cellulose), acrylic resins, polycarbonate resins, and polyester resins such as polyethylene terephthalate. The layer thickness of the base film 105 is, for example, 10 to 500 μm, preferably 20 to 300 μm.

(2) Light diffusing layer The light diffusing layer 106 is a layer having a light transmissive resin 106b as a base material, and a light diffusing agent 106a is dispersed in the light transmissive resin 106b.

The translucent resin 106b is not particularly limited as long as it has translucency. For example, an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin or a cured product of a thermosetting resin, A thermoplastic resin, a cured product of metal alkoxide, or the like can be used. Among these, an ionizing radiation curable resin is preferable because it has high hardness and can impart high scratch resistance as a light diffusion film provided on the surface of the liquid crystal display device. In the case of using an ionizing radiation curable resin, a thermosetting resin, or a metal alkoxide, the translucent resin 106b is formed by curing the resin by irradiation or heating with ionizing radiation.

Examples of the ionizing radiation curable resin include polyfunctional acrylates such as polyhydric alcohol acrylic acid or methacrylic acid ester; polyisocyanates synthesized from diisocyanate, polyhydric alcohol and acrylic acid or methacrylic acid hydroxy ester, and the like. Examples include functional urethane acrylate. Besides these, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can also be used.

Examples of the thermosetting resin include a phenol resin, a urea melamine resin, an epoxy resin, an unsaturated polyester resin, and a silicone resin in addition to a thermosetting urethane resin composed of an acrylic polyol and an isocyanate prepolymer.

Examples of thermoplastic resins include cellulose derivatives such as acetylcellulose, nitrocellulose, acetylbutylcellulose, ethylcellulose, and methylcellulose; vinyl acetate and copolymers thereof, vinyl chloride and copolymers thereof, vinylidene chloride and copolymers thereof, and the like. Acetal resins such as polyvinyl formal and polyvinyl butyral; Acrylic resins and copolymers thereof, Acrylic resins such as methacrylic resins and copolymers; Polystyrene resins; Polyamide resins; Polyester resins; Polycarbonate resins Etc.

As the metal alkoxide, a silicon oxide matrix made of a silicon alkoxide material can be used. Specifically, it is tetramethoxysilane, tetraethoxysilane, or the like, and can be made into an inorganic or organic-inorganic composite matrix (translucent resin) by hydrolysis or dehydration condensation.

Further, as the light diffusing agent 106a in the light diffusing layer 106, organic fine particles or inorganic fine particles having translucency can be used. For example, organic fine particles made of acrylic resin, melamine resin, polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, etc., and made of calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, glass, etc. Examples include inorganic fine particles. Organic polymer balloons and glass hollow beads can also be used. The light diffusing agent 106a may be composed of one kind of fine particles or may contain two or more kinds of fine particles. The shape of the light diffusing agent 106a may be any of a spherical shape, a flat shape, a plate shape, a needle shape, an indefinite shape, and the like, but a spherical shape or a substantially spherical shape is preferable.

The weight average particle diameter of the light diffusing agent 106a is preferably 0.1 μm or more and 15 μm or less, and more preferably 1 μm or more and 10 μm or less. When the weight average particle size of the light diffusing agent 106a is less than 0.1 μm, visible light having a wavelength region of 380 nm to 800 nm cannot be sufficiently scattered, and the light diffusing property of the light diffusing film 701 becomes insufficient, and the relative scattered light It may be difficult to make the intensity L ₂ / L ₁ 0.0002% or more, and as a result, a wide viewing angle may not be obtained. When the weight average particle size exceeds 15 μm, sufficient light scattering properties may not be obtained, and the relative scattered light intensity L ₂ / L ₁ may not be 0.0002% or more.

The ratio of the standard deviation of the particle size to the weight average particle size (standard deviation / weight average particle size) of the light diffusing agent 106a is preferably 0.5 or less, and more preferably 0.4 or less. When the ratio exceeds 0.5, a light diffusing agent having an extremely large particle size may be included, and protrusion-like defects may occur frequently on the surface of the light diffusing layer. Doing so will cause a reduction in display quality. The weight average particle diameter and the standard deviation of the particle diameter of the light diffusing agent 106a are measured using a Coulter Multisizer (manufactured by Beckman Coulter, Inc.) based on the Coulter principle (pore electrical resistance method).

The content of the light diffusing agent 106a in the light diffusion layer 106 is preferably 5 parts by weight or more and 100 parts by weight or less, with respect to 100 parts by weight of the translucent resin 106b, and is 10 parts by weight or more and 40 parts by weight or less. It is more preferable.

The refractive index difference between the light diffusing agent 106a and the translucent resin 106b is preferably in the range of 0.01 to 0.2, and more preferably 0.05 to 0.15. By setting the difference in refractive index between the light diffusing agent 106a and the translucent resin 106b within the above range, appropriate internal scattering occurs due to the difference in refractive index between the light diffusing agent 106a and the translucent resin 106b. It becomes easy to control the total haze and internal haze of the polarizing plate within the predetermined range.

Further, it is preferable that the surface of the light diffusion layer 106 (the surface opposite to the base film 105) is formed only by the light-transmitting resin 106b. That is, it is preferable that the light diffusing agent 106 a does not protrude from the surface of the light diffusing layer 106 and is completely buried in the light diffusing layer 106. For this reason, the layer thickness of the light diffusion layer 106 is preferably 1 to 3 times the weight average particle diameter of the light diffusion agent 106a. When the layer thickness of the light diffusing layer 106 is less than 1 times the weight average particle diameter of the light diffusing agent 106 a, the light diffusing agent 106 a easily protrudes from the surface of the light diffusing layer 106. Further, when the layer thickness of the light diffusion layer 106 exceeds three times the weight average particle diameter of the light diffusion agent 106a, the layer thickness of the light diffusion layer 106 becomes too thick.

The layer thickness of the light diffusion layer 106 is preferably in the range of 1 to 30 μm. When the layer thickness of the light diffusing layer 106 is less than 1 μm, sufficient scratch resistance may not be exhibited when the light diffusing polarizing plate is disposed on the viewing side surface of the liquid crystal display device. Moreover, when the layer thickness exceeds 30 μm, the amount of curl generated in the produced light diffusion film becomes large, and the handleability in pasting to other layers becomes poor.

(3) Manufacturing method Application | coating of the resin liquid containing the light-diffusion agent 106a and the translucent resin 106b on the base film 105 is a gravure coat method, a micro gravure coat method, a rod coat method, a knife coat method, An air knife coating method, a kiss coating method, a die coating method, or the like can be used. When applying the resin liquid, as described above, the coating film thickness is adjusted so that the thickness of the light diffusion layer 106 is 1 to 3 times the weight average particle diameter of the translucent fine particles 106b. It is preferable to do.

Various surface treatments may be applied to the surface of the base film 105 (surface on the light diffusion layer side) for the purpose of improving the coating property of the resin liquid or improving the adhesion with the light diffusion layer 106. Examples of the surface treatment include corona discharge treatment, glow discharge treatment, acid surface treatment, alkali surface treatment, and ultraviolet irradiation treatment. Further, another layer such as a primer layer (easily adhesive layer) may be formed on the base film 105, and the resin liquid may be applied on the other layer.

In order to improve the adhesion between the base film 105 and the light diffusing pressure-sensitive adhesive layer 104, the surface of the base film 105 opposite to the light diffusing layer 106 is subjected to the surface treatment as described above. Is preferred.

The light diffusing film 102 can also be obtained by applying a resin liquid in which the light diffusing agent 106a is dispersed on the base film 105 and then transferring the mirror surface or uneven surface of the mold to the surface of the layer made of the resin liquid. Can be formed. For example, a light diffusion layer having a flat surface can be formed by transferring the mirror surface by bringing the mirror surface of a mold having a mirror surface (mirror surface mold) into close contact with the surface of the layer made of the resin liquid. . In addition, the light diffusing layer having the uneven surface shape as shown in FIG. 2 has the uneven surface of the mold (embossing mold) having an uneven surface adhered to the surface of the layer made of the resin liquid. An uneven surface can be transferred and formed. The mirror surface mold may be a mirror surface metal roll, and the embossing mold may be an embossing metal roll.

When ionizing radiation curable resin, thermosetting resin or metal alkoxide is used as the resin for forming the translucent resin 106b, a layer made of the above resin solution is formed and dried (removing the solvent) as necessary. Depending on the condition, the surface of the layer made of the resin liquid is in close contact with or close to the mold mirror surface or uneven surface, and then irradiated with ionizing radiation (when using ionizing radiation curable resin) or heated (thermosetting) The layer made of the resin liquid is cured by using a mold resin or metal alkoxide. The ionizing radiation can be appropriately selected from ultraviolet rays, electron beams, near ultraviolet rays, visible light, near infrared rays, infrared rays, X-rays, etc. depending on the type of resin contained in the resin liquid. Among these, ultraviolet rays, An electron beam is preferable, and ultraviolet rays are particularly preferable because of easy handling and high energy.

As the ultraviolet light source, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. An ArF excimer laser, a KrF excimer laser, an excimer lamp, synchrotron radiation, or the like can also be used. Among these, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a xenon arc, and a metal halide lamp are preferably used.

As the electron beam, 50 to 1000 keV emitted from various electron beam accelerators such as Cockloft Walton type, Bande graph type, resonance transformation type, insulation core transformation type, linear type, dynamitron type, and high frequency type, preferably 100 Mention may be made of electron beams having an energy of ˜300 keV.

Next, a preferred embodiment for manufacturing the light diffusion film 102 will be described. In the manufacturing method according to the preferred embodiment, in order to continuously manufacture the light diffusion film 102, a step of continuously feeding the base film 105 wound in a roll shape, a resin liquid in which the light diffusion agent 106a is dispersed And a step of drying as necessary, a step of curing a layer made of a resin liquid, and a step of winding up the obtained light diffusion film 102.

FIG. 3 is a schematic diagram showing a configuration of a manufacturing apparatus for carrying out such a manufacturing method. First, the base film 105 is continuously unwound by the unwinding device 301. Next, a resin liquid in which the light diffusing agent 106a is dispersed is applied onto the unwound base film 105 using a coating device 302 and a backup roll 303 facing the coating device 302. Next, when a solvent is contained in the resin liquid, the resin liquid is dried by passing it through a dryer 304. Next, the base film 105 provided with the layer made of the resin liquid is placed between the mirror metal roll or the embossing metal roll 305 and the nip roll 306, and the layer made of the resin liquid is a mirror metal roll or It winds so that it may contact | adhere with the metal roll 305 for embossing. Thereby, the mirror surface of the mirror surface metal roll or the uneven surface of the metal roll for embossing is transferred to the surface of the layer made of the resin liquid.

Next, a layer made of a resin liquid is obtained by irradiating ultraviolet rays from an ultraviolet irradiation device 308 through the base film 105 in a state where the base film 105 is wound around a mirror surface metal roll or an embossing metal roll 305. Is cured. Since the irradiated surface becomes high temperature due to ultraviolet irradiation, the mirror surface metal roll or the embossing metal roll 305 preferably includes a cooling device for adjusting the surface temperature to about room temperature to 80 ° C. . Further, one or a plurality of ultraviolet irradiation devices 308 can be used. The base film 105 (light diffusion film 102) on which the light diffusion layer 106 is formed is peeled off from the mirror surface metal roll or the embossing metal roll 305 by the peeling roll 307.

The light diffusion film 102 produced as described above is taken up by the take-up device 309. At this time, for the purpose of protecting the light diffusing layer 106, it is wound up with a surface protective film made of polyethylene terephthalate, polyethylene, or the like attached to the surface of the light diffusing layer 106 through an adhesive layer having removability. Also good.

In addition, after peeling from the mirror surface metal roll or the embossing metal roll 305 by the peeling roll 307, additional ultraviolet irradiation may be performed. Further, instead of performing ultraviolet irradiation in a state of being wound around a mirror surface metal roll or an embossing metal roll 305, a base film 105 on which a layer made of an uncured resin liquid is formed is used as a mirror surface metal roll or After peeling from the embossing metal roll 305, it may be cured by irradiation with ultraviolet rays.

(Light diffusion adhesive layer)
In the light diffusing polarizing plate 100 of the present embodiment, the light diffusing pressure-sensitive adhesive layer 104 bonds the first protective film 110 and the base film 105 of the light diffusing film 102. The light diffusable pressure-sensitive adhesive layer 104 has a total haze of 10% to 80%.

The light diffusing pressure-sensitive adhesive layer 104 has a structure in which a light diffusing agent 104a having light scattering ability is dispersed in a light-transmitting pressure-sensitive adhesive 104b. The light diffusing agent 104a to be used is not particularly limited as long as it scatters light, and either organic fine particles or inorganic fine particles can be used. As the material and shape of the light diffusing agent 104a, the same material as the light diffusing agent 106a in the light diffusing layer 106 of the light diffusing film 102 described above can be used.

If the particle size of the light diffusing agent 104a is too small, the light scattering ability is not expressed, and if it is too large, the display quality deteriorates when the light diffusing polarizing plate is applied to a liquid crystal display device. The thickness is preferably 15 μm or less and more preferably 0.5 μm or more and 10 μm or less. The addition amount of the light diffusing agent 104a can be appropriately set according to the desired light scattering ability. Preferably, it is blended in the range of 0.5 to 40 parts by weight, particularly 1 to 20 parts by weight with respect to 100 parts by weight of the light-transmitting pressure-sensitive adhesive 104b to be dispersed.

As the translucent adhesive 104b used for the light diffusable adhesive layer 104, a conventionally well-known appropriate adhesive can be used, for example, an acrylic adhesive, a urethane adhesive, a silicone adhesive, etc. It is done. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The light diffusing pressure-sensitive adhesive layer 104 is formed by applying a coating liquid (for example, a coating liquid containing an organic solvent) containing such a light transmissive pressure-sensitive adhesive 104b and the light diffusing agent 104a to a base film (for example, the first protective film 110 or the like). The light diffusing film 102 can be provided by a method such as coating on a base film 105 or the like of the light diffusion film 102 by a die coater or a gravure coater and drying. In addition, a light diffusable pressure-sensitive adhesive layer is formed in the same manner as above on a plastic film (referred to as a separate film) that has been subjected to a release treatment, and the formed sheet-like light diffusable pressure-sensitive adhesive layer is used as a base film. It can also be provided by a transfer method. The thickness of the light diffusing pressure-sensitive adhesive layer 104 is not particularly limited, but is preferably in the range of 2 to 40 μm.

(Protective film)
The first protective film 110 and the second protective film 109 may be simple protective films having no optical function, or may be protective films having both optical functions such as a retardation film and a brightness enhancement film. . The material of the

protective films

109 and 110 is not particularly limited, but examples thereof include a cyclic polyolefin resin film, a cellulose acetate resin film made of a resin such as triacetyl cellulose and diacetyl cellulose, polyethylene terephthalate, and polyethylene naphthalate. Examples thereof include films that have been widely used in the art, such as polyester resin films made of resins such as phthalate and polybutylene terephthalate, polycarbonate resin films, acrylic resin films, and polypropylene resin films.

Examples of the cyclic polyolefin-based resin include appropriate commercial products such as Topas (registered trademark) (manufactured by Ticona), Arton (registered trademark) (manufactured by JSR Corporation), ZEONOR (registered trademark) (Nippon ZEON ( ZEONEX (registered trademark) (manufactured by Nippon Zeon Co., Ltd.), Apel (registered trademark) (manufactured by Mitsui Chemicals, Inc.) can be suitably used. When such a cyclic polyolefin resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, pre-formed cyclic polyolefins such as Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), ZEONOR (registered trademark) film (manufactured by Optes Co., Ltd.), etc. A commercial product of a film made of a resin may be used.

The cyclic polyolefin resin film may be uniaxially stretched or biaxially stretched. An arbitrary retardation value can be imparted to the cyclic polyolefin-based resin film by stretching. Stretching is usually performed continuously while unwinding the film roll, and is stretched in the heating furnace in the roll traveling direction, the direction perpendicular to the traveling direction, or both. The temperature of the heating furnace is usually in the range from the vicinity of the glass transition temperature of the cyclic polyolefin resin to the glass transition temperature + 100 ° C. The stretching ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times in one direction.

Since the cyclic polyolefin resin film generally has poor surface activity, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment is performed on the surface to be bonded to the polarizing film. preferable. Among these, plasma treatment and corona treatment that can be performed relatively easily are preferable.

Examples of the cellulose acetate-based resin film include commercially available products such as Fujitac (registered trademark) TD80 (manufactured by Fuji Film Co., Ltd.), Fujitac (registered trademark) TD80UF (manufactured by Fuji Film Co., Ltd.), and Fujitac (registered trademark). TD80UZ (Fuji Film Co., Ltd.), Fujitac (registered trademark) TD40UZ (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta Opto Co., Ltd.), KC4UY (Konica Minolta Opto Co., Ltd.) are preferably used. be able to.

A liquid crystal layer or the like may be formed on the surface of the cellulose acetate-based resin film in order to improve viewing angle characteristics. Moreover, in order to provide a phase difference, what stretched the cellulose acetate type-resin film may be used. The cellulose acetate-based resin film is usually subjected to a saponification treatment in order to improve the adhesiveness with the polarizing film. As the saponification treatment, a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be employed.

Optical layers such as a hard coat layer, an antiglare layer, and an antireflection layer can be formed on the surfaces of the

protective films

109 and 110 as described above. The method for forming these optical layers on the surface of the protective film is not particularly limited, and a known method can be used.

The thickness of the

protective films

109 and 110 is preferably as thin as possible from the request for thinning, preferably 88 μm or less, and more preferably 48 μm or less. On the other hand, if it is too thin, the strength is lowered and the processability is poor, and therefore it is preferably 5 μm or more.

The first protective film 110 and the second protective film 109 may be the same or different. The

protective films

109 and 110 and the polarizing film 101 are bonded through, for example, an unillustrated adhesive layer or pressure-sensitive adhesive layer. The bonding surfaces of the

protective films

109 and 110 may be subjected to easy adhesion treatment such as corona discharge treatment and primer treatment (formation of a primer layer) prior to bonding with an adhesive or a pressure-sensitive adhesive.

(1) Adhesive layer The adhesive used for bonding the

protective films

109 and 110 and the polarizing film 101 is, for example, an aqueous adhesive using a polyvinyl alcohol resin aqueous solution, an aqueous two-component urethane emulsion adhesive, or the like. Is mentioned. In the case of using a cellulose acetate film hydrophilized by a saponification process or the like as the

protective films

109 and 110, a polyvinyl alcohol resin aqueous solution is suitably used as an aqueous adhesive for bonding to the polarizing film 101. Polyvinyl alcohol resins used as adhesives include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as other single quantities copolymerizable with vinyl acetate. And vinyl alcohol copolymers obtained by saponifying the copolymer with the polymer, and modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups. A polyhydric aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound, or the like may be added as an additive to the water-based adhesive. When such a water-based adhesive is used, the adhesive layer obtained therefrom is usually 1 μm or less.

The method of bonding the polarizing film 101 and the

protective films

109 and 110 using an aqueous adhesive is not particularly limited. For example, the adhesive is uniformly applied to the surfaces of the polarizing film 101 and / or the

protective films

109 and 110. The method of apply | coating, laminating | stacking another film on an application | coating surface, bonding with a roll etc., and drying is mentioned. Usually, after the preparation, the adhesive is applied at a temperature of 15 to 40 ° C., and the laminating temperature is usually in the range of 15 to 30 ° C.

When using a water-based adhesive, the polarizing film 101 and the

protective films

109 and 110 are bonded, and then dried to remove water contained in the water-based adhesive. The temperature of the drying furnace is preferably 30 ° C to 90 ° C. When the temperature is lower than 30 ° C., the adhesive surface between the polarizing film 101 and the

protective films

109 and 110 tends to be easily peeled off. If it is 90 ° C. or higher, the optical performance may be deteriorated by heat. The drying time can be 10 to 1000 seconds, and particularly from the viewpoint of productivity, it is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds.

After drying, it may be further cured at room temperature or slightly higher, for example, at a temperature of about 20 to 45 ° C. for about 12 to 600 hours. The temperature at the time of curing is generally set lower than the temperature adopted at the time of drying.

Moreover, a photocurable adhesive can also be used as an adhesive when the polarizing film 101 and the

protective films

109 and 110 are bonded together. Examples of the photocurable adhesive include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator.

As a method of applying an adhesive to the polarizing film 101 or the

protective films

109 and 110, a conventionally known method can be used. For example, a casting method, a Mayer bar coating method, a gravure coating method, a comma coater method, a doctor plate method, a die coating method, a dip coating method, a spraying method and the like can be mentioned. In the casting method, the polarizing film 101 or the

protective films

109 and 110 that are the objects to be coated are moved in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between them, and an adhesive is allowed to flow onto the surface. It is a method of spreading.

After applying an adhesive on the surface of the polarizing film 101 or the

protective film

109, 110, the polarizing film 101 and the

protective film

109, 110 are bonded together by sandwiching them with a nip roll or the like through the adhesive application surface. In addition, an adhesive is dropped between the polarizing film 101 and the

protective films

109 and 110 in a state where the polarizing film 601 and the

protective films

109 and 110 are overlapped, and then the laminated body is pressed uniformly with a roll or the like. A method of spreading out can also be suitably used. In this case, a metal, rubber, or the like can be used as the material of the roll. Furthermore, after dropping an adhesive agent between the polarizing film 101 and the

protective films

109 and 110, a method of passing the laminate between the rolls and pressurizing and spreading is preferably employed. In this case, these rolls may be made of the same material or different materials. The thickness of the adhesive layer after being bonded using the nip roll or the like before drying or curing is preferably 5 μm or less and 0.01 μm or more.

In order to improve the adhesion, the surface of the polarizing film 101 and / or the

protective film

109, 110 is appropriately subjected to a surface treatment such as a plasma treatment, a corona treatment, an ultraviolet irradiation treatment, a flame (flame) treatment, or a saponification treatment. You may give it. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

When a photocurable resin is used as the adhesive, the photocurable adhesive is cured by irradiating active energy rays after the polarizing film 101 and the

protective films

109 and 110 are joined. The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low pressure mercury lamp, the medium pressure mercury lamp, the high pressure mercury lamp, the ultrahigh pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excitation mercury lamp, a metal halide lamp and the like are preferably used.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW / it is preferable that the cm ^2. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when it is 6000 mW / cm ² or less, the epoxy is generated by the heat radiated from the light source and the heat generated when the photo-curable adhesive is cured. There is little risk of yellowing of the resin or deterioration of the polarizing film. The light irradiation time to the photocurable adhesive is not particularly limited and is applied according to the photocurable adhesive to be cured, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time. Is preferably set to 10 to 10,000 mJ / cm ² . When the cumulative amount of light to the photocurable adhesive is 10 mJ / cm ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to allow the curing reaction to proceed more reliably, and at 10,000 mJ / cm ² or less. In some cases, the irradiation time does not become too long and good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 μm, preferably 0.01 μm or more and 2 μm or less, more preferably 0.01 μm or more and 1 μm or less.

When the photocurable adhesive is cured by irradiation with active energy rays, it is cured under conditions that do not deteriorate the functions of the polarizing plate, such as the degree of polarization, the transmittance and the hue of the polarizing film 101, and the transparency of the

protective films

109 and 110. It is preferable to carry out.

(2) Adhesive layer The adhesive used for bonding the

protective films

109 and 110 and the polarizing film 101 is usually based on an acrylic resin, a styrene resin, a silicone resin, etc., and an isocyanate compound. And a composition to which a crosslinking agent such as an epoxy compound or an aziridine compound is added. Furthermore, like the light diffusable pressure-sensitive adhesive layer 104 described above, a pressure-sensitive adhesive layer containing a light diffusing agent and exhibiting light diffusibility can also be used.

The thickness of the pressure-sensitive adhesive layer is preferably 1 to 40 μm, but it is preferably thinly applied as long as the workability and durability characteristics are not impaired, and more preferably 3 to 25 μm. When the thickness is 3 to 25 μm, it has good processability and is also suitable for suppressing the dimensional change of the polarizing film. When the pressure-sensitive adhesive layer is less than 1 μm, the tackiness is lowered, and when it exceeds 40 μm, problems such as the pressure-sensitive adhesive protruding easily occur.

In the method of bonding the

protective films

109 and 110 to the polarizing film 101 with an adhesive, the

protective film

109 and 110 may be bonded to the polarizing film 101 after providing an adhesive layer on the surface of the

protective film

109 or 110. After providing the pressure-sensitive adhesive layer on the surface,

protective films

109 and 110 may be bonded thereto.

The method for forming the pressure-sensitive adhesive layer is not particularly limited, and a solution containing each component including the above-mentioned base polymer is applied to the

protective film

109, 110 surface or the polarizing film 101 surface and dried. After forming the pressure-sensitive adhesive layer, the

protective films

109 and 110 and the polarizing film 101 may be bonded together, or after forming the pressure-sensitive adhesive layer on the separator, the surface is transferred to the

protective film

109 or 110 surface or the polarizing film 101 surface. And may be laminated. Further, when the pressure-sensitive adhesive layer is formed on the surface of the

protective film

109, 110 or the polarizing film 101, an adhesion treatment is performed on the surface of the

protective film

109, 110 or the polarizing film 101, or one or both of the pressure-sensitive adhesive layer, if necessary. Corona treatment or the like may be performed.

(Other optical layers)
The light diffusing polarizing plate of the present embodiment having the above-described configuration can be used by stacking other optical layers in practical use. The

protective films

109 and 110 may have the functions of these optical layers. Examples of other optical layers include a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties, a film with an antiglare function having an uneven shape on the surface, and a surface antireflection function. Examples thereof include an attached film, a reflective film having a reflective function on the surface, a transflective film having both a reflective function and a transmissive function, and a viewing angle compensation film.

Commercially available products corresponding to reflective polarizing films that transmit certain types of polarized light and reflect polarized light that exhibits the opposite properties include DBEF (available from 3M, Sumitomo 3M Co., Ltd.), APF (Available from 3M, available from Sumitomo 3M Limited). Examples of the viewing angle compensation film include an optical compensation film coated with a liquid crystal compound on the surface of the substrate and oriented, a retardation film made of a polycarbonate resin, and a retardation film made of a cyclic polyolefin resin. Commercially available products corresponding to an optical compensation film coated with a liquid crystal compound on the substrate surface and oriented are WV film (Fuji Film Co., Ltd.), NH film (Shin Nippon Oil Co., Ltd.), NR Examples include films (manufactured by Nippon Oil Corporation). Commercial products corresponding to retardation films made of cyclic polyolefin resins include Arton (registered trademark) film (manufactured by JSR Corporation), Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), Zeonor ( Registered trademark) film (manufactured by Optes Co., Ltd.). These optical layers are preferably disposed on the surface of the light diffusion film 102. The light diffusing layer 106 of the light diffusing film 102 and these optical layers are similar to each other through the same adhesive layer or pressure-sensitive adhesive layer as described in the bonding of the

protective films

109 and 110 and the polarizing film 101 described above. It can be bonded by the method.

[Second Embodiment]
FIG. 4 is a schematic cross-sectional view showing the light diffusing polarizing plate of the second embodiment. In FIG. 4, a light diffusing polarizing plate 200 has a polarizing film 101, and a light diffusing film 102, a light diffusing pressure-sensitive adhesive layer 104, and a surface treatment film 107 are laminated in this order on one surface of the polarizing film 101. A protective film 109 is laminated on the other surface of the polarizing film 101. The light diffusion film 102 includes a base film 105 and a light diffusion layer 106. Since the base film 105 is laminated immediately above the polarizing film 101, it also serves as a protective film. The light diffusing polarizing plate 200 of this embodiment is partially different from the light diffusing polarizing plate 100 of the first embodiment in the stacking order, but the polarizing film 101, the protective film 109, the light diffusing film 102, and the light diffusing property. Since the detailed structure of the adhesive layer 104 is as described in the first embodiment, the same members are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, the light diffusive pressure-sensitive adhesive layer 104 plays a role of bonding the light diffusion layer 106 of the light diffusion film 102 and the surface treatment film 107.

(Surface treatment film)
The surface treatment film 107 is a film in which one surface of the transparent resin film (the surface opposite to the light diffusable pressure-sensitive adhesive layer 104 side) is optically treated. It can be a film in which a surface treatment layer having a desired optical function is formed on one surface. As the transparent resin film, for example, a resin film made of cellulose acetate resin such as TAC (triacetyl cellulose), acrylic resin such as polymethyl methacrylate, polycarbonate resin, and polyester resin such as polyethylene terephthalate is used. Can do. The thickness of the transparent resin film is, for example, 10 to 500 μm, preferably 20 to 300 μm.

As the surface treatment film 107, for example, the surface treatment layer is an antiglare layer having surface irregularities that uses irregular reflection on the surface to reduce or prevent reflection on the display screen (that is, the above optical treatment is performed). Anti-glare film (which is anti-glare treatment) and anti-reflection layer that reduces or prevents reflection on the display screen by reducing or preventing reflection of external light incident on the display screen by the surface treatment layer (ie, And the optical treatment is an antireflection treatment).

As an antiglare film, for example, a gold resin having a predetermined surface irregularity shape is formed on an ultraviolet curable resin layer formed after coating an ultraviolet curable resin composition containing or not containing fine particles on a transparent resin film. The UV curable resin layer is cured while pressing the uneven surface of the mold to apply a predetermined surface unevenness to the antiglare layer, or an ultraviolet curable resin composition containing fine particles on the transparent resin film. After the processing, it is possible to use an anti-glare layer provided with predetermined surface irregularities by fine particles by curing the ultraviolet curable resin layer without using a mold. A commercially available anti-glare film can also be used as the anti-glare film.

Examples of the antireflection film include a low refractive index layer made of a material lower than the refractive index of the light diffusive pressure-sensitive adhesive layer 104 as an antireflection layer, and a refractive index of the light diffusable pressure sensitive adhesive layer 104. Examples include an antireflection layer having a laminated structure of a high refractive index layer composed of a high material and a low refractive index layer composed of a material lower than the refractive index of the high refractive index layer. The low refractive index layer is made of, for example, silica, metal fluoride fine particles (LiF, MgF, 3NaF / AlF, AlF, Na ₃ AlF ₆ etc.), fine particles having voids inside (hollow silica fine particles etc.), fluorine-containing polymer, etc. It can contain a low refractive index material and a binder resin. The binder resin forming material may be a conventionally known material, such as polysiloxane resin, hydrolyzate of silicon alkoxide, light or thermosetting multi-branched compound (dendrimer, hyperbranched polymer, etc.), other light or thermosetting resin. Can be used. One or more of other layers such as a hard coat layer and an antistatic layer may be interposed between the transparent resin film and the low refractive index layer or the high refractive index layer. A commercially available antireflection film can also be used as the antireflection film.

[Third embodiment]
FIG. 5 is a schematic cross-sectional view showing the light diffusing polarizing plate of the third embodiment. In FIG. 5, the light diffusing polarizing plate 300 includes a polarizing film 101, and a first protective film 110, a light-transmitting pressure-sensitive adhesive layer 108, a light diffusing film 102, a light diffusing on one surface of the polarizing film 101. The adhesive layer 104 and the surface treatment film 107 are laminated in this order, and the second protective film 109 is laminated on the other surface of the polarizing film 101. The same members as those in the first embodiment and the second embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, the light diffusive pressure-sensitive adhesive layer 104 plays a role of bonding the light diffusion layer 106 of the light diffusion film 102 and the surface treatment film 107. Moreover, the translucent adhesive layer 108 plays the role which bonds the 1st protective film 110 and the base film 105 of a light-diffusion film.

The translucent pressure-sensitive adhesive layer 108 is not limited as long as it has translucency and has an action of bonding the first protective film 110 and the base film 105 of the light diffusion film. In 1st Embodiment, the adhesive layer demonstrated as an adhesive layer used for bonding of the

protective films

109 and 110 and the polarizing film 101 is used suitably.

The light diffusing polarizing plate having the above-described configuration is preferably used as a polarizing plate on the viewing side of a liquid crystal display device, and typically a liquid crystal display so that the light diffusing film 102 is positioned on the viewing side from the polarizing sheet 101. Built into the device.

<Liquid crystal display device>
Next, the liquid crystal display device according to the present invention will be described. The liquid crystal display device of the present invention comprises a backlight device, a light diffusion means, a backlight side polarizing plate, a liquid crystal cell, and the light diffusing polarizing plate of the present invention in this order. FIG. 6 is a schematic sectional view showing a preferred example of the liquid crystal display device of the present invention. A liquid crystal display device 400 in FIG. 6 is a normally white mode TN liquid crystal display device, and includes a backlight device 402, a light diffusion means 403, a backlight side polarizing plate 404, and a pair of

transparent substrates

411a and 411b. A liquid crystal cell 401 in which a liquid crystal layer 412 is provided, and a light diffusing polarizing plate 405 according to this embodiment which is a viewing side polarizing plate are arranged in this order. The backlight side polarizing plate 404 and the light diffusing polarizing plate 405 are disposed so that their transmission axes have a crossed Nicols relationship.

When each member is bonded using an adhesive layer or an adhesive layer when configuring a liquid crystal display device, the adhesive layer or the adhesive layer is bonded to the

protective films

109 and 110 and the polarizing film 101 in the above. The same material as that described as the pressure-sensitive adhesive layer or adhesive layer used for combining can be used, or the same material as that described above as the light-diffusing pressure-sensitive adhesive layer 104 can also be used. . For example, when the light diffusing polarizing plate 405 and the liquid crystal cell 401 are bonded, an adhesive layer similar to the above-described light diffusing adhesive layer 104 can be used.

The backlight device 402 is a direct-type backlight device including a rectangular parallelepiped case 421 having an upper surface opening and a plurality of cold cathode tubes 422 as linear light sources arranged in parallel in the case 421. The light diffusion means 403 is provided on the light diffusion plate 403a disposed on the backlight device 402 and on the front side of the light diffusion plate 403a (between the light diffusion plate 403a and the backlight side polarizing plate 404). And an optical deflection plate (prism sheet) 403b.

In the liquid crystal display device 400 having such a configuration, the light emitted from the backlight device 402 is diffused by the light diffusing plate 403a of the light diffusing means 403, and then the light incident surface of the liquid crystal cell 401 by the light deflecting plate 403b. Predetermined directivity with respect to the normal direction is given. The directivity with respect to the normal direction is set higher than that of the conventional apparatus. The light having a predetermined directivity is polarized by the backlight side polarizing plate 404 and enters the liquid crystal cell 401. Light incident on the liquid crystal cell 401 is emitted from the liquid crystal cell 401 after the polarization state is controlled by the liquid crystal layer 412. The light emitted from the liquid crystal cell 401 is diffused by the light diffusing polarizing plate 405.

Thus, in the liquid crystal display device of this embodiment, the directivity in the normal direction of the light incident on the liquid crystal cell 401 in the light diffusing unit 403 is made higher than that in the conventional case, that is, the incident light to the liquid crystal cell 401 is reduced. It is assumed that the light is more concentrated than before, and is further diffused by the light diffusing polarizing plate 405. As a result, image quality such as color reproducibility superior to that of the conventional apparatus can be obtained.

Hereafter, the structural member which comprises the liquid crystal display device of this embodiment is demonstrated in detail.
(Liquid crystal cell)
The liquid crystal cell 401 includes a pair of

transparent substrates

411a and 411b arranged to face each other with a predetermined distance by a spacer, and a liquid crystal layer 412 formed by sealing liquid crystal between the pair of

transparent substrates

411a and 411b. The pair of

transparent substrates

411a and 411b are each formed by laminating a transparent electrode and an alignment film, and the liquid crystal is aligned by applying a voltage based on display data between the transparent electrodes. The display method of the liquid crystal cell 401 is the TN method in the above example, but a display method such as an IPS method or a VA method may also be adopted.

(Backlight device)
The backlight device 402 includes a rectangular parallelepiped case 421 having an upper surface opening, and a plurality of cold cathode tubes 422 as linear light sources arranged in parallel in the case 421. The case 421 is formed from a resin material or a metal material, and at least the inner peripheral surface of the case 421 may be white or silver from the viewpoint of reflecting the light emitted from the cold cathode tube 422 on the inner peripheral surface of the case 421. desirable. As a light source, LEDs of various shapes such as a linear shape can be used in addition to a cold cathode tube. When the linear light source is used, the number of the linear light sources to be arranged is not particularly limited, but the distance between the centers of the adjacent linear light sources is in the range of 15 mm to 150 mm from the viewpoint of suppressing luminance unevenness on the light emitting surface. It is preferable. The backlight device 402 used in the present embodiment is not limited to the direct type shown in FIG. 5, but is a sidelight type in which a linear light source or a point light source is arranged on the side surface of the light guide plate, or Various types such as a planar light source type can be used.

(Light diffusion means)
7 and 8 are cross-sectional views showing a preferred example of the light diffusing means. As shown in FIG. 7, the light diffusing unit 403 includes a light diffusing plate 403 a disposed on the backlight device 402, a front surface side of the light diffusing plate 403 a (a light diffusing plate 403 a and a backlight side polarizing plate 404. And a light deflector plate (prism sheet) 403b provided between the two. For example, as shown in FIG. 7, the light diffusing plate 403 a can be a film or a sheet in which a light diffusing agent 440 is dispersed and mixed with a base material 430. As the base material 430, polycarbonate resin, methacrylic resin, methyl methacrylate-styrene copolymer resin, acrylonitrile-styrene copolymer resin, methacrylic acid-styrene copolymer resin, polystyrene resin, polyvinyl chloride resin Polyolefin resins such as polypropylene and polymethylpentene, cyclic polyolefin resins, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamide resins, polyarylate resins, and polyimide resins can be used.

Further, the light diffusing agent 440 mixed and dispersed in the base material 430 is not particularly limited as long as it is a fine particle made of a material having a refractive index different from that of the material to be the base material 430. For example, it is different from the material to be the base material 430. Organic fine particles consisting of various acrylic resins, melamine resins, polyethylene resins, polystyrene resins, organic silicone resins, acrylic-styrene copolymer resins, etc., and calcium carbonate, silica, aluminum oxide, barium carbonate, barium sulfate, titanium oxide, Examples include inorganic fine particles made of glass. Only one type of light diffusing agent 440 may be used, or two or more types may be used in combination. An organic polymer balloon or glass hollow beads can also be used as the light diffusing agent 440. The weight average particle diameter of the light diffusing agent 440 is preferably in the range of 0.5 to 30 μm. The light diffusing agent 440 may have a spherical shape, a flat shape, a plate shape, a needle shape, or the like, but is preferably a spherical shape.

On the other hand, the light deflection plate (prism sheet) 403b has a flat surface on the light incident surface side (backlight device 402 side) and a tapered cross section on the light emission surface (surface facing the backlight side polarizing plate 404). A plurality of polygonal prisms, preferably triangular linear prisms 450, are formed in parallel. Examples of the material of the light deflector 403b include polycarbonate resins, ABS resins, methacrylic resins, methyl methacrylate-styrene copolymer resins, polystyrene resins, acrylonitrile-styrene copolymer resins, and polyolefin resins such as polyethylene and polypropylene. Examples thereof include resins. As a method for producing the light deflection plate 403b, a normal thermoplastic resin molding method can be used, and examples thereof include hot press molding using a mold and extrusion molding. The thickness of the light deflection plate 403b is usually 0.1 to 15 mm, preferably 0.5 to 10 mm.

The light diffusing plate 403a and the light deflecting plate 403b may be integrally formed, or may be formed separately and then joined. Further, in the case of separately producing and joining, the light diffusing plate 403a and the light deflecting plate 403b may be contacted via an air layer. Further, the light diffusion plate 403a and the light deflection plate 403b may be arranged apart from each other.

As shown in FIG. 8, the light diffusing means 403 may be one in which a light diffusing function is imparted by dispersing and mixing a light diffusing agent 440 to a light deflecting plate 403b having a light deflecting function.

FIG. 9 shows another example of the light diffusing means. As shown in FIG. 9, the light diffusing unit 403 may include two light deflecting plates (prism sheets) disposed on the front side of the light diffusing plate 403a. In this case, referring to FIG. 9, in the light deflection plate 403b disposed on the side closer to the light diffusion plate 403a, the direction of the ridge line 451 of the linear prism 450 is substantially the same as the transmission axis direction of the backlight side polarizing plate 404. The light deflection plate 403b ′ arranged so as to be parallel to each other and disposed on the front side of the light deflection plate 403b has the direction of the ridge line 451 ′ of the linear prism 450 ′ as the transmission axis direction of the light diffusing polarizing plate 405. Are preferably arranged so as to be substantially parallel to each other. With such a configuration, the luminance in the front direction of the liquid crystal display device can be further improved. However, it is arranged so that the direction of the ridge line 451 ′ of the linear prism 450 ′ of the light deflector 403b ′ is substantially parallel to the transmission axis direction of the backlight side polarizing plate 404, and the linear prism 450 of the light deflector 403b. It is also possible to arrange the ridge line 451 so that the direction of the ridge line 451 is substantially parallel to the transmission axis direction of the light diffusing polarizing plate 405.

FIG. 10 shows an example of a method of measuring the luminance value in the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell with respect to the light diffusion means. The light distribution characteristic of the light that has passed through the light diffusing means 403 is that the luminance value in the direction inclined by 70 ° from the normal direction of the light incident surface of the liquid crystal cell 401 is the front luminance value, that is, the light incident surface of the liquid crystal cell 401. It is preferable that the luminance value is 20% or less with respect to the luminance value in the normal direction, and the emitted light from the light diffusion means 403 includes non-parallel light. A more preferable light distribution characteristic is to prevent light exceeding 60 ° from the normal line of the light incident surface of the liquid crystal cell 401. Normally, as shown in FIG. 6, the back surface of the light diffusing means 403 and the light incident surface of the liquid crystal cell 401 are arranged in parallel, so that the 70 ° direction of the light incident surface of the liquid crystal cell 401 is normal. For example, as shown in FIG. 10, the luminance value is a normal line to the xy plane when the longitudinal direction of the light diffusing unit 403 is the x direction and the plane parallel to the back surface of the light diffusing unit 403 is the xy plane. The luminance value is in the direction of 70 ° with respect to the z axis, and preferably the luminance value in the direction in which the angle formed with the z axis on the xz plane is 70 °. In order to achieve such a light distribution characteristic, for example, the shape of the linear prism 450 (and / or the linear prism 450 ') having a triangular cross section of the light deflection plate 403b may be adjusted.

The apex angle θ (see FIGS. 7 and 8) of the

linear prisms

450 and 450 ′ is preferably in the range of 60 to 120 °, more preferably 90 to 110 °. As for the shape of this triangle, an equal side and an unequal side can be arbitrary, but an isosceles triangle is preferable when concentrating in the normal direction of the liquid crystal cell 401 (front direction of the liquid crystal display device). Also, the prism surface composed of linear prisms is arranged sequentially so that the bases corresponding to the apex angles of the triangles are adjacent to each other, and a plurality of linear prisms are arranged so as to be substantially parallel to each other. Is preferred. In this case, the V-shaped grooves formed by the apexes of the linear prisms and the adjacent linear prisms may be curved as long as the light collecting ability is not significantly reduced. The distance between the ridgelines of the linear prism (distance d shown in FIGS. 7 and 8) is usually in the range of 10 μm to 500 μm, and preferably in the range of 30 μm to 200 μm.

FIG. 11 is a diagram for explaining the definition of non-parallel light. As shown in FIG. 11, non-parallel light is parallel to the emission surface, which is 1 m away from the inside of a circle having a diameter of 1 cm on the emission surface of the light diffusing means 403 and is 1 m away from the normal direction of the emission surface. When viewed as a projection image on a simple observation surface, the light has an emission characteristic such that the minimum half-value width of the in-plane luminance distribution of the projection image is 30 cm or more.

(Backlight side polarizing plate)
As the backlight-side polarizing plate 404, a polarizing film in which a protective film is bonded to one side or both sides can be usually used. As a polarizing film and a protective film, what was mentioned above about the light diffusable polarizing plate can be used.

(Phase difference plate)
FIG. 12 is a schematic cross-sectional view showing another preferred example of the liquid crystal display device of the present invention. As shown in FIG. 12, the liquid crystal display device of the present embodiment can include a retardation plate 406. In the liquid crystal display device 400 ′ shown in FIG. 12, the retardation film 406 is disposed between the backlight side polarizing plate 404 and the liquid crystal cell 401. This phase difference plate 406 has a substantially zero phase difference in a direction perpendicular to the surface of the liquid crystal cell 401, has no optical effect from the front, and has a phase difference when viewed from an oblique direction. It is expressed and compensates for the phase difference generated in the liquid crystal cell 401. As a result, a wider viewing angle can be obtained, and better display quality and color reproducibility can be obtained. The retardation plate 406 can be disposed between the backlight side polarizing plate 404 and the liquid crystal cell 401, or between the light diffusing polarizing plate 405 and the liquid crystal cell 401, or both. The retardation film 406 can be laminated on the protective film of the backlight-side polarizing plate 404, or can be laminated directly on the polarizing film so as to function as a protective film. The same applies to the light diffusing polarizing plate 405.

As the phase difference plate 406, for example, a polycarbonate resin or a cyclic olefin polymer resin is used as a film, and this film is further biaxially stretched, or a liquid crystalline monomer is applied to the film, and its molecular arrangement is changed by a photopolymerization reaction. Immobilized ones are listed. The phase difference plate 406 optically compensates for the alignment of the liquid crystal, and therefore has a refractive index characteristic opposite to that of the liquid crystal alignment. Specifically, for a TN mode liquid crystal cell, for example, “WV film” (manufactured by FUJIFILM Corporation), for an STN mode liquid crystal display cell, for example, “LC film” (manufactured by Nippon Oil Corporation), For IPS mode liquid crystal display cells, for example, a biaxial retardation film, for VA mode liquid crystal display cells, for example, a retardation plate or a biaxial retardation film combining a A plate and a C plate, a π cell For the mode liquid crystal display cell, for example, “OCB WV film” (manufactured by FUJIFILM Corporation) can be suitably used.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following examples, the relative scattered light intensity and haze of the light diffusing polarizing plate, the thickness of the light diffusing layer of the light diffusing film, the bending strength of the light diffusing film, the haze of the adhesive layer, and the light diffusing agent used. The method of measuring the weight average particle size of is as follows.

(A) Relative scattered light intensity Using an optically transparent adhesive, measurement is performed using a measurement sample in which a light diffusing polarizing plate is bonded to a glass substrate on the side opposite to the light diffusing film. It was. He-Ne laser parallel light (wavelength 543.5 nm) was incident from the glass substrate surface side of the measurement sample into the normal direction of the light diffusing polarizing plate, and was tilted by 40 ° from the normal direction of the light diffusion layer side. The intensity L ₂ of the laser beam transmitted in the direction A3 was measured, and the relative scattered light intensity L ₂ / L ₁ was calculated as a value obtained by dividing the intensity L ₂ of the transmitted scattered light by the light intensity L ₁ of the light source. For measurement, a “3292 03 optical power sensor” manufactured by Yokogawa Electric Corporation and a “3292 optical power meter” manufactured by the same company were used. In performing this measurement, a light source for irradiating a He—Ne laser was disposed at a position of 430 mm from the glass substrate. The power sensor, which is a light receiver, was arranged in a direction A3 inclined by 40 ° from the normal direction on the light diffusion layer side of the sample at a position 280 mm from the emission point of the laser beam. The measurement of the light intensity _{L 1} of the light source was performed by placing the power sensor to the position of 710mm (= 430mm + 280mm) from the light source.

(B) Haze Using an optically transparent adhesive, measurement was performed using a measurement sample in which a light diffusing polarizing plate was bonded to a glass substrate on the surface opposite to the light diffusing film. For the measurement of total haze and internal haze, a haze transmittance meter (haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd.) according to JIS K 7136 was used. About an adhesive layer, by the method similar to the light diffusable polarizing plate mentioned above using the sample for a measurement which bonded the adhesive sheet containing an adhesive layer to the glass substrate using an optically transparent adhesive. Measurements were made.

(C) Thickness of the light diffusion layer The thickness of the light diffusion film is measured using DIGIMICRO MH-15 (main body) and ZC-101 (counter) manufactured by NIKON, and the thickness of the base sheet is subtracted from the measurement layer thickness. Thus, the thickness of the light diffusion layer was measured.

(D) Bending strength of light diffusing film About the bending strength of the light diffusing film, the mandrel test was implemented using the metal rod of 8 mm diameter using the mandrel testing machine based on JISK5600. At this time, a case where abnormality such as cracking or whitening was observed in the coating film (light diffusion layer) was evaluated as x, and a case where abnormality was not observed was evaluated as o.

(E) Weight average particle diameter of light diffusing agent and standard deviation of particle diameter Based on the Coulter principle (pore electrical resistance method), measurement was performed using a Coulter Multisizer (manufactured by Beckman Coulter).

<Light diffusion film>
[Preparation of mirror surface metal roll]
The surface of an iron roll having a diameter of 200 mm (STKM13A by JIS) was subjected to industrial chrome plating, and the surface was then mirror-polished to produce a mirror-surface metal roll. The Vickers hardness of the chrome-plated surface of the obtained mirror surface metal roll was 1000. The Vickers hardness was measured according to JIS Z 2244 using an ultrasonic hardness meter MIC10 (manufactured by Krautkramer).

[Light diffusion film]
(1) Production Example 1
60 parts by weight of pentaerythritol triacrylate and 40 parts by weight of polyfunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate) are mixed in a propylene glycol monomethyl ether solution so that the solid content concentration becomes 60% by weight. To obtain an ultraviolet curable resin composition. The refractive index of the cured product after removing propylene glycol monomethyl ether from the composition and curing with ultraviolet rays was 1.53.

Next, polystyrene particles having a weight average particle size of 7.2 μm, a standard deviation of 0.52 μm, and a refractive index of 1.59 are used as a light diffusing agent with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition. 35 parts by weight and 5 parts by weight of “Lucirin TPO” (manufactured by BASF, chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) as a photopolymerization initiator are added, and the solid content is 60% by weight. A coating solution was prepared by diluting with propylene glycol monomethyl ether.

This coating solution was coated on a 80 μm thick triacetyl cellulose (TAC) film (base film) and dried for 1 minute in a dryer set at 80 ° C. The base film after drying was brought into close contact with the mirror surface of the mirror-finished metal roll produced above with a rubber roll so that the ultraviolet curable resin composition layer was on the roll side. In this state, light from a high-pressure mercury lamp having an intensity of 20 mW / cm ² is irradiated from the base film side so as to be 300 mJ / cm ^{2 in} terms of the amount of h-line conversion, and the ultraviolet curable resin composition layer is cured and flattened. The light-diffusion film which consists of a light-diffusion layer and a base film which have an appropriate surface was obtained. The thickness of the light diffusion layer after curing was 8 μm. Moreover, the above-mentioned bending strength test was done about the obtained light-diffusion film. Evaluation was (circle).

(2) Production Example 2
A light diffusion film was obtained using the same material and the same method as in Production Example 1. The thickness of the light diffusion layer after curing was 13 μm. Moreover, the above-mentioned bending strength test was done about the obtained light-diffusion film. Evaluation was (circle).

(3) Production Example 3
A light diffusing film was obtained by the same material and the same method as in Production Example 1 except that the amount of the light diffusing agent was 43 parts by weight with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition. The thickness of the light diffusion layer after curing was 10 μm. Moreover, the above-mentioned bending strength test was done about the obtained light-diffusion film. Evaluation was x.

<Adhesive layer>
(1) Production example a
A base paint in which 1.5 parts by weight of an isocyanate curing agent (D-90; manufactured by Soken Chemical Co., Ltd.) is added to 100 parts by weight of an acrylic pressure-sensitive adhesive having a refractive index of 1.50. .43, 3 parts by weight of silicon resin beads having a weight average particle diameter of 1.0 μm were added, and the mixture was stirred with an agitator for 1 hour to prepare an adhesive. Then, this pressure-sensitive adhesive was applied to an 8 μm-thick release sheet (PET3801, manufactured by Lintec Corporation), dried to form a pressure-sensitive adhesive layer, and then a release sheet (K-14, manufactured by Teijin Limited) on the pressure-sensitive adhesive layer. Were bonded together to obtain an adhesive sheet. The thickness of the pressure-sensitive adhesive layer after drying was 25 μm, the total haze of the pressure-sensitive adhesive layer was 25%, and a light diffusable pressure-sensitive adhesive layer was obtained.

(2) Production example b
An adhesive sheet was obtained in the same manner as in Production Example a except that no light diffusing agent was blended. The total haze of the pressure-sensitive adhesive layer was 0%.

(3) Production example c
Adhesive prepared by mixing an appropriate amount of silicone resin beads “Tospearl 145” (made by Momentive Performance Materials Japan Co., Ltd.) as a light diffusing agent with a general-purpose acrylic transparent adhesive. Except for the points used, a pressure-sensitive adhesive sheet was obtained using the same material and the same method as in Production Example a. The thickness of the pressure-sensitive adhesive layer after drying was 25 μm, the total haze of the pressure-sensitive adhesive layer was 33%, and a light diffusable pressure-sensitive adhesive layer was obtained.

(4) Production example d
Adhesive prepared by mixing an appropriate amount of silicone resin beads “Tospearl 145” (made by Momentive Performance Materials Japan Co., Ltd.) as a light diffusing agent with a general-purpose acrylic transparent adhesive. Except for the points used, a pressure-sensitive adhesive sheet was obtained using the same material and the same method as in Production Example a. The thickness of the pressure-sensitive adhesive layer after drying was 25 μm, the total haze of the pressure-sensitive adhesive layer was 60%, and a light diffusable pressure-sensitive adhesive layer was obtained.

(5) Production example e
Adhesive prepared by mixing an appropriate amount of silicone resin beads “Tospearl 145” (made by Momentive Performance Materials Japan Co., Ltd.) as a light diffusing agent with a general-purpose acrylic transparent adhesive. Except for the points used, a pressure-sensitive adhesive sheet was obtained using the same material and the same method as in Production Example a. The thickness of the pressure-sensitive adhesive layer after drying was 25 μm, the total haze of the pressure-sensitive adhesive layer was 70%, and a light diffusable pressure-sensitive adhesive layer was obtained.

<Light diffusing polarizing plate>
[Production]
(1) Example 1
One release sheet is peeled off from the light diffusing film produced in Production Example 1 and the adhesive layer produced in Production Example a is applied to obtain a laminate, and the relative scattered light intensity and haze are measured by the above methods. did. Thereafter, the other release sheet was further peeled off and attached to an iodine polarizing plate (“TRW842AP7” manufactured by Sumitomo Chemical Co., Ltd.), and an iodine polarizing plate, an adhesive layer, and a light diffusion film were laminated in this order. The light diffusable polarizing plate of Example 1 was obtained.

(2) Example 2
One release sheet is peeled off from the light diffusion film produced in Production Example 3 and the adhesive layer produced in Production Example c is applied to obtain a laminate, and the relative scattered light intensity and haze are measured by the above methods. did. Thereafter, the other release sheet was further peeled off and attached to an iodine polarizing plate (“TRW842AP7” manufactured by Sumitomo Chemical Co., Ltd.), and an iodine polarizing plate, an adhesive layer, and a light diffusion film were laminated in this order. The light diffusable polarizing plate of Example 2 was obtained.

(3) Example 3
One release sheet is peeled off to the light diffusion film produced in Production Example 3, the adhesive layer produced in Production Example d is applied, and the other release sheet is further peeled off to remove the iodine-based polarizing plate (Sumitomo Chemical Co., Ltd.). A light diffusing polarizing plate of Example 3 in which an iodine polarizing plate, an adhesive layer, and a light diffusing film were laminated in this order was attached to “TRW842AP7”).

(4) Example 4
One release sheet is peeled off from the light diffusion film produced in Production Example 3 and the pressure-sensitive adhesive layer produced in Production Example e is applied, and the other release sheet is further peeled off to remove the iodine-based polarizing plate (Sumitomo Chemical Co., Ltd.). A light diffusing polarizing plate of Example 4 in which an iodine polarizing plate, an adhesive layer, and a light diffusing film were laminated in this order was attached to “TRW842AP7”).

(5) Comparative Example 1
One release sheet is peeled off from the light diffusion film produced in Production Example 1 and the pressure-sensitive adhesive layer produced in Production Example b is applied, and the other release sheet is further peeled off to remove the iodine-based polarizing plate (Sumitomo Chemical Co., Ltd.). A light diffusing polarizing plate of Comparative Example 1 in which an iodine polarizing plate, an adhesive layer, and a light diffusing film were laminated in this order was attached to “TRW842AP7”).

(6) Comparative Example 2
One release sheet is peeled off to the light diffusion film produced in Production Example 2 and the light diffusable pressure-sensitive adhesive layer produced in Production Example b is applied, and the other release sheet is further peeled off to remove the iodine-based polarizing plate ( It was affixed to “TRW842AP7” manufactured by Sumitomo Chemical Co., Ltd.) to obtain a light diffusing polarizing plate of Comparative Example 2 in which an iodine polarizing plate, an adhesive layer, and a light diffusing film were laminated in this order.

[Measurement of optical properties]
About the obtained light diffusable polarizing plate, the total haze and relative scattered light intensity were measured by the above-mentioned method. Table 1 shows the results. Since the surface haze of the obtained light diffusing polarizing plate is substantially 0%, the internal haze is substantially the same value as the total haze.

<Liquid crystal display device>
[Production]
A liquid crystal display device was produced using the obtained light diffusing polarizing plate, and the image quality was comprehensively evaluated based on the front contrast, the viewing angle, the degree of moire, and the degree of whitishness. First, a light diffusing plate was arranged on the backlight device of the Panasonic IPS mode 32-inch LCD TV “VIERA TH-32LZ85”, and a plurality of linear prisms having an apex angle of 95 ° were arranged in parallel. Two prism films were used, and these were arranged between the light diffusion plate and the backlight side polarizing plate. At this time, one prism film (prism film close to the backlight device) is arranged so that the direction of the ridgeline of the linear prism is substantially parallel to the transmission axis of the backlight side polarizing plate, and the other prism film ( The prism film near the backlight side polarizing plate) was arranged so that the direction of the ridgeline of the linear prism was substantially parallel to the transmission axis of the viewing side polarizing plate (light diffusing polarizing plate) described later. In the light emitted from the prism film, the luminance value in the direction of 70 ° with respect to the normal direction was 10% of the luminance value in the normal direction. Further, the viewing-side polarizing plate was peeled off, and the light-diffusing polarizing plates of Examples 1 to 4 and Comparative Examples 1 and 2 were bonded to the backlight-side polarizing plate so as to be crossed Nicols, and the liquid crystal display device Got.

[Evaluation]
The image quality of the liquid crystal display device obtained as described above was visually evaluated based on the viewing angle, the degree of moire and the degree of whitishness. The evaluation criteria are as follows. The evaluation results are shown in Table 1.
A: No abnormality is observed in the display quality.
○: There is almost no abnormality in the display quality.
X: Abnormality is recognized in display quality such as gradation collapse, inversion, contrast reduction, and moire generation.

The light diffusion films of Examples 1 to 4 (Production Examples 1 and 3) are thinner than the light diffusion film (Production Example 2) used in Comparative Example 2. As shown in Table 1, according to the liquid crystal display device using the light diffusing polarizing plate according to Examples 1 to 4, good image quality can be obtained. In the liquid crystal display device using the light diffusing polarizing plate of Comparative Example 2 in which the light diffusing film is thickened to increase the light diffusing property, the same image quality can be obtained, but in this case, the light diffusing film is weak against bending. It becomes difficult to handle. Therefore, according to the present invention, it is possible to contribute to the thinning of the liquid crystal display device by thinning the polarizing film while exhibiting good display characteristics, and the mechanical strength is strong and the handling becomes easy.

The light diffusing polarizing plate according to the present invention is a polarizing plate provided with a light diffusing function by providing a light diffusing layer, and has a sufficient mechanical strength, so that it is good when incorporated in a liquid crystal display device. Display with high image quality. Therefore, the light diffusing polarizing plate and the liquid crystal display device using the same according to the present invention are suitable for use in mobile phones, personal computer monitors, televisions, liquid crystal projectors, and the like.

DESCRIPTION OF SYMBOLS 10,100,200,300,405 ... Light diffusable polarizing plate, 101 ... Polarizing film, 102 ... Light diffusing film, 104 ... Light diffusing adhesive layer, 104a ... Light diffusing Agent, 104b ... translucent adhesive, 105 ... substrate film, 106 ... light diffusion layer, 106a ... light diffusion agent, 106b ... translucent resin, 107 ... surface Treated film, 108 ... translucent adhesive layer, 109, 110 ... protective film, 301 ... unwinding device, 302 ... coating device, 303 ... backup roll, 304 ... Dryer, 305 ... mirror metal roll or embossing metal roll, 306 ... nip roll, 307 ... peeling roll, 308 ... UV irradiation device, 309 ... winding device, 400, 400 ... Liquid crystal display device, 401 ... Liquid crystal cell, 402 ... Backlight device, 403 ... Light diffusing means, 403a ... Light diffusing plate, 403b, 403b '... Light deflecting plate, 404 ... Backlight side polarizing plate, 406 ... Phase difference plate, 411a, 411b ... Transparent substrate, 412 ... Liquid crystal layer, 421 ... Case, 422 ... Cold cathode tube, 430 ... -Base material, 440 ... Light diffusing agent, 450, 450 '? ... linear prism, 451, 451'? ... ridge line of linear prism.

Claims

A light diffusing polarizing plate comprising a polarizing film, a light diffusing film, and a light diffusing pressure-sensitive adhesive layer,
The total haze of the light diffusing polarizing plate is more than 40% and 85% or less,
The internal haze of the light diffusing polarizing plate is more than 40% and 85% or less,
The light diffusable polarizing plate whose total haze of the said light diffusable adhesive layer is 10% or more and 80% or less.
Comprising a pair of protective films laminated on both sides of the polarizing film;
The light diffusable polarizing plate according to claim 1, wherein the light diffusable pressure-sensitive adhesive layer is laminated on a surface of one of the protective films opposite to the polarizing film side.
The light diffusable polarizing plate according to claim 1, wherein the light diffusive pressure-sensitive adhesive layer is laminated on one surface of the light diffusing film.
Comprising a pair of protective films laminated on both sides of the polarizing film;
The light diffusing polarizing plate according to claim 1, wherein the one protective film, the polarizing film, the other protective film, the light diffusing pressure-sensitive adhesive layer, and the light diffusing film are laminated in this order.
Laser that is incident on the light diffusable polarizing plate and is emitted in the normal direction of the light diffusing polarizing plate with respect to laser light having a wavelength of 543.5 nm that is emitted after passing through the polarizing film and the light diffusing film in this order. relative intensity of the light L 1, the ratio L 2 / L 1 of the laser light intensity L 2 emitted from the normal direction to the 40 ° inclined direction is less than 0.01% not less than 0.0002%, wherein Item 5. The light diffusing polarizing plate according to any one of Items 1 to 4.
A backlight device, a light diffusing means, a backlight side polarizing plate, a liquid crystal cell, and the light diffusing polarizing plate according to any one of claims 1 to 5 are arranged in this order,
The liquid crystal display device in which the light diffusing polarizing plate is disposed so that the polarizing film and the light diffusing film are positioned in this order from the side close to the liquid crystal cell.
The emitted light from the light diffusing means has a luminance in a direction inclined by 70 ° from the normal direction of the light diffusing means with respect to the luminance in the normal direction of the light diffusing means being 20% or less, and The liquid crystal display device according to claim 6, wherein the emitted light includes non-parallel light.
The light diffusing means includes a light diffusing plate and a light deflecting plate,
The liquid crystal display device according to claim 6 or 7, wherein the light diffusion plate and the light deflection plate are arranged in this order from the backlight device side.
9. The liquid crystal display device according to claim 6, wherein the liquid crystal cell is a TN liquid crystal cell, an IPS liquid crystal cell, or a VA liquid crystal cell.