JP2012027460A - Light diffusing polarizer and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light diffusing polarizer having sufficient light diffusion, which also excellently exhibits other optical functions such as an antidazzle function and an antireflection function, and to provide a liquid crystal display device using the polarizer.SOLUTION: A light diffusing polarizer comprises a polarizing film 101, a light diffusing film 102 which is laminated on the polarizing film 101, and a surface treated film 103 made of a transparent resin film 107 which is laminated on the light diffusing film 102 and has one optically treated surface, and a liquid crystal display device uses the polarizer. The light diffusing film 102 includes a light diffusing layer 106 which contains translucent fine particles 106b dispersed in a translucent resin 106a in the range from 20 pts.wt. to 100 pts.wt. relative to the translucent resin 106a of 100 pts.wt. The light diffusing layer 106 of the light diffusing film 102 and the surface treated film 103 are laminated to each other through an adhesive layer or a bonding layer 104.

Description

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

  In recent years, application of liquid crystal display devices to mobile phones, personal computer monitors, televisions, liquid crystal projectors, and the like 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 such a problem of viewing angle characteristics, a technique for imparting a light diffusion function to a front-side polarizing plate is conventionally known. For example, JP 2009-301014 A (Patent Document 1) discloses a polarizing plate having a relatively high light diffusibility (“second light diffusion layer” in Patent Document 1) on the front side (viewing side) of a liquid crystal cell. Is disclosed). This second light diffusing layer is, for example, a polarizing plate and a resin layer (light diffusing layer) provided on the front side of the polarizing plate and provided with a light diffusing function containing a relatively large amount of filler (light diffusing agent). ).

JP 2009-301014 A

  On the other hand, for the purpose of further improving the visibility of the liquid crystal display device, it is possible to prevent or reduce external light from being reflected on the display surface on the outermost surface of the liquid crystal display device, that is, the outermost surface of the front-side polarizing plate. Optical processing such as anti-glare processing or anti-reflection processing for preventing or reducing reflection of external light incident on the display surface may be performed. In order for these optical treatments to fully exhibit a predetermined function, the shape of the surface on which the optical treatment is performed needs to be precisely controlled.

  However, the light diffusion layer containing a relatively large amount of filler, such as the light diffusion layer of the front-side polarizing plate described in Patent Document 1, may not always have a sufficiently controlled surface shape. In such a case, it is difficult to directly apply the optical treatment as described above to the surface of the light diffusing layer, or even if it is possible to directly apply the optical treatment itself, Certain functions such as an antireflection function may not be expressed well.

  Accordingly, an object of the present invention is a polarizing plate having sufficient light diffusibility, and further a new light diffusing polarizing plate that exhibits excellent other optical functions such as an anti-glare function and an anti-reflection function, and uses the same. It is to provide a liquid crystal display device.

  The present invention relates to a polarizing film, a light diffusing film laminated on the polarizing film, and a surface-treated film having an optical treatment applied to one surface of a transparent resin film laminated on the light diffusing film. The light diffusing film has a light diffusing layer in which 20 to 100 parts by weight of translucent fine particles are dispersed in the translucent resin with respect to 100 parts by weight of the translucent resin. The light diffusing polarizing plate in which the light diffusing layer of the light diffusing film and the surface treatment film are bonded to each other via an adhesive layer or an adhesive layer is provided.

  In the light diffusing polarizing plate of the present invention, the surface treatment film has a surface not subjected to optical treatment, and the light diffusion layer and the surface not subjected to optical treatment of the surface treatment film are adhesive. It is preferable that the light diffusion layer and the surface treatment film are bonded to each other through an agent layer or an adhesive layer.

  The surface-treated film is, for example, an antiglare film in which an antiglare treatment is performed on one surface of the transparent resin film, or an antireflection film in which an antireflection treatment is performed on one surface of the transparent resin film. be able to.

  It is preferable that a light-diffusion film is equipped with a transparent base film and the said light-diffusion layer laminated | stacked on this transparent base film. The light diffusion layer of such a light diffusion film can be formed by applying a resin liquid in which translucent fine particles are dispersed on a transparent substrate film. The light diffusing layer is formed by applying a resin liquid in which translucent fine particles are dispersed on a transparent substrate film, and then transferring the mirror surface or the uneven surface of the mold to the surface of the layer made of the resin liquid. May be formed.

  Moreover, this invention provides a liquid crystal display device provided with a backlight apparatus, a light-diffusion means, a backlight side polarizing plate, a liquid crystal cell, and the said light diffusable polarizing plate in this order. In the liquid crystal display device of the present invention, the light diffusing polarizing plate is disposed so that the polarizing film side faces the liquid crystal cell.

  In the liquid crystal display device of the present invention, the emitted light from the light diffusing means has a luminance in a direction inclined by 70 ° from the normal direction of the light incident surface of the liquid crystal cell is 20% or less with respect to the luminance in the normal direction. It is preferable to have light distribution characteristics and include non-parallel light.

  The light diffusing means may include a light diffusing plate and a light deflecting plate 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.

  ADVANTAGE OF THE INVENTION According to this invention, while having sufficient light diffusibility, the light diffusable polarizing plate which shows suitably other optical functions, such as a glare-proof function and an antireflection function, can be provided. The liquid crystal display device of the present invention to which the light diffusing polarizing plate is applied has high viewing angle characteristics and also has other optical functions imparted to the light diffusing polarizing plate, and is excellent in visibility.

It is a schematic sectional drawing which shows a preferable example of the light diffusable polarizing plate of this invention. It is a schematic sectional drawing which shows another preferable example 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 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.

<Light diffusing polarizing plate>
FIG. 1 and FIG. 2 are schematic sectional views showing preferred examples of the light diffusing polarizing plate of the present invention. The light diffusing polarizing plates 100 and 200 shown in FIGS. 1 and 2 according to the present invention are laminated on the polarizing film 101, the light diffusing film 102 laminated on the polarizing film 101, and the light diffusing film 102. A surface treatment film 103 made of a transparent resin film 107 having one surface subjected to optical treatment (specifically, a surface treatment layer 108 is provided), and a light diffusion layer 106 of the light diffusion film 102. The surface treatment film 103 is bonded to each other through an adhesive layer or an adhesive layer 104.

  In the light diffusing polarizing plates 100 and 200 shown in FIGS. 1 and 2, the light diffusing film 102 includes a transparent base film 105 and a light diffusing layer 106 laminated on the transparent base film 105. The light diffusion layer 106 is made of a resin layer in which translucent fine particles 106b are dispersed in a translucent resin 106a. The light diffusion film 102 is laminated on the polarizing film 101 so that the transparent base film 105 side faces the polarizing film 101. In the light diffusing film 102 of the present invention, the surface of the light diffusing layer 106 may be constituted by a flat surface as in the example shown in FIG. 1, or from the uneven surface as in the example shown in FIG. It may be configured.

  The surface treatment film 103 includes a transparent resin film 107 and a surface treatment layer 108 laminated on one surface of the transparent resin film 107. The surface treatment film 103 is a surface opposite to the surface treatment layer 108 of the transparent resin film 107 (a surface on which the surface treatment film 103 is not subjected to optical treatment), and the adhesive layer or the adhesive layer 104 is interposed therebetween. And bonded to the light diffusion layer 106 of the light diffusion film 102.

  In addition, although the protective film 109 is a film for protecting the other surface of the polarizing film 101, it is not necessarily required and may be omitted. Further, instead of the protective film 109, an optical compensation film such as a retardation film (retardation plate) may be bonded.

  According to the light diffusable polarizing plate of the present invention having the above configuration, the light diffusion layer 106 of the light diffusion film 102 and the surface treatment film 103 formed by laminating the surface treatment layer 108 on the transparent resin film 107, Since it is bonded through the pressure-sensitive adhesive layer or the adhesive layer 104, a surface-treated film having a desired optical function can be surely formed on the light diffusion layer 106 regardless of the control accuracy of the surface shape of the light diffusion layer 106. Further, it is possible to perform lamination while completely eliminating the influence of the surface shape of the light diffusion layer 106 on the structure and shape of the surface treatment layer 108. Therefore, the light diffusing polarizing plate of the present invention exhibits a predetermined optical function by the surface treatment layer 108 as well as a light diffusing function.

Hereinafter, the light diffusable polarizing plate of the present invention will be described in more detail.
(Polarizing film)
As the polarizing film 101, for example, a dichroic dye or iodine is adsorbed and oriented on a film made of polyvinyl alcohol resin, polyvinyl acetate resin, ethylene / vinyl acetate (EVA) resin, polyamide resin, polyester resin, or the like. Examples thereof include a polyvinyl alcohol / polyvinylene copolymer containing a molecular chain oriented with a dichroic dehydrated product of polyvinyl alcohol (polyvinylene) in a molecularly oriented polyvinyl alcohol film. In particular, a uniaxially stretched polyvinyl alcohol resin film obtained by adsorbing and orienting a dichroic dye or iodine is suitably used as a polarizing film. Although there is no restriction | limiting in particular in the thickness of the polarizing film 101, From viewpoints, such as thickness reduction of a light diffusable polarizing plate, 100 micrometers or less are preferable, More preferably, it is 10-50 micrometers, More preferably, it is 25-35 micrometers.

(Light diffusion film)
As shown in FIGS. 1 and 2, the light diffusion film 102 used in the present invention includes a transparent base film 105 and a light diffusion layer 106 laminated on the transparent base film 105, and the light diffusion layer 106 Is preferably made of a resin layer in which translucent fine particles (light diffusing agent) 106b are dispersed in translucent resin 106a.

  The transparent substrate film 105 is not particularly limited as long as it is optically transparent, and for example, glass or plastic film can be used. As the plastic film, those having appropriate transparency and mechanical strength are preferable. Specifically, cellulose acetate resins such as TAC (triacetyl cellulose), acrylic resins, polycarbonate resins, and polyester systems such as polyethylene terephthalate. Resin etc. are mentioned. The thickness of the transparent substrate film 105 is, for example, 10 to 500 μm, and preferably 20 to 300 μm.

  The light diffusing layer 106 is a layer having a translucent resin 106a as a base material, and translucent fine particles 106b are dispersed in the translucent resin 106a. The translucent resin 106a 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, ionizing radiation curable resins are preferred because they can impart high hardness and scratch resistance. In the case of using an ionizing radiation curable resin, a thermosetting resin, or a metal alkoxide, the translucent resin 106a 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 or the like using a silicon alkoxide material as a raw 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 transmissive fine particles 106b, a light diffusing agent made of light transmissive organic fine particles or inorganic fine particles can be used. For example, organic fine particles made of acrylic resin, melamine resin, polyethylene, polystyrene, organic silicone resin, acrylic-styrene copolymer, 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 translucent fine particles 106b may be composed of one kind of fine particles, or may contain two or more kinds of fine particles. The shape of the translucent fine particles 106b 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 translucent fine particles 106b is preferably 0.5 to 15 μm, and more preferably 3 to 8 μm. When the weight average particle size of the light-transmitting fine particles 106b is less than 0.5 μm, the light diffusing property of the light diffusing film 102 becomes insufficient, and as a result, when a light diffusing polarizing plate is applied to a liquid crystal display device, Sufficient wide viewing angle performance may not be obtained. Moreover, when the weight average particle diameter exceeds 15 μm, sufficient light diffusibility may not be obtained. The translucent fine particles 106b preferably have a ratio of standard deviation of particle diameter to weight average particle diameter (standard deviation / weight average particle diameter) of 0.5 or less, preferably 0.4 or less. More preferred. When the ratio exceeds 0.5, the translucent fine particles include particles having extremely large particle diameters. As a result, the surface of the light diffusion film 102 becomes too rough, and thus the surface-treated film is bonded. Occasionally, problems such as air bubble biting may occur. The weight average particle diameter and the standard deviation of the particle diameter of the translucent fine particles 106b 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 transmissive fine particles 106b in the light diffusion layer 106 is 20 parts by weight or more and 100 parts by weight or less, preferably 20 parts by weight or more and 70 parts by weight or less, with respect to 100 parts by weight of the light transmissive resin 106a. Preferably they are 25 to 60 weight parts, More preferably, they are 30 to 55 weight parts. When the content of the light transmissive fine particles 106b is less than 20 parts by weight with respect to 100 parts by weight of the light transmissive resin, the light diffusing film 102 has insufficient light diffusibility. When a polarizing plate is applied, sufficient wide viewing angle performance is difficult to obtain. Further, when the content of the light transmissive fine particles 106b exceeds 100 parts by weight with respect to 100 parts by weight of the light transmissive resin, the haze of the light diffusing film 102 becomes excessively large, resulting in a decrease in transparency of the light diffusing film 102. However, when a light diffusing polarizing plate is applied to the liquid crystal display device, the front contrast is lowered. In the present invention, a relatively large amount of light-transmitting fine particles (light diffusing agent) is contained in the light diffusing layer as described above, but the surface treatment film is bonded to the light diffusing layer via the pressure-sensitive adhesive layer or the adhesive layer. Therefore, there is no difficulty in forming the surface treatment layer, and the surface treatment layer can be reliably and easily produced without compromising the structure and shape necessary for the surface treatment layer to exhibit a predetermined optical function. The treatment layer can be applied to the light diffusing polarizing plate.

  The refractive index difference between the translucent fine particles 106b and the translucent resin 106a is preferably in the range of 0.04 to 0.15. By setting the refractive index difference between the translucent fine particles 106b and the translucent resin 106a within the above range, appropriate internal scattering occurs due to the refractive index difference between the translucent fine particles 106b and the translucent resin 106a. A light diffusive film having moderately high diffusibility can be obtained.

  Moreover, it is preferable that the surface (surface on the opposite side to the transparent base film 105) of the light-diffusion layer 106 is formed only by the translucent resin 106a. That is, it is preferable that the translucent fine particles 106 b do not protrude from the surface of the light diffusion layer 106 and are completely buried in the light diffusion layer 106. Therefore, the thickness of the light diffusion layer 106 is preferably 1 to 3 times the weight average particle diameter of the translucent fine particles 106b. When the thickness of the light diffusing layer 106 is less than 1 times the weight average particle diameter of the translucent fine particles 106b, the surface of the light diffusing layer 106 is rough when the light diffusing polarizing plate is applied to the liquid crystal display device. Since it will become too much, problems, such as a bubble biting, may arise at the time of surface treatment film bonding. Further, when the thickness of the light diffusion layer 106 exceeds three times the weight average particle diameter of the translucent fine particles 106b, the thickness of the light diffusion layer 106 becomes too large, and the light diffusion property of the light diffusion film 102 is accordingly increased. As a result, when the light diffusing polarizing plate is applied to the liquid crystal display device, the front contrast may be lowered.

  The thickness of the light diffusion layer 106 is preferably in the range of 1 to 30 μm. When the thickness of the light diffusion layer 106 is less than 1 μm, sufficient scratch resistance required for the light diffusion film 102 disposed on the viewing side surface of the liquid crystal display device may not be provided. On the other hand, when the thickness exceeds 30 μm, the amount of curl generated in the produced light diffusing film 102 becomes large, and the handleability in the manufacturing process of the light diffusing polarizing plate is deteriorated.

  As shown in FIGS. 1 and 2, the surface shape of the light diffusion layer 106 may be formed of a flat surface or an uneven surface, but the degree of unevenness (roughness of surface unevenness) ) Is preferably such that the unevenness is filled with an adhesive or an adhesive.

The light diffusion film 102 preferably has a total haze of 30% to 70% and an internal haze of 30% to 70%. “Total haze” means the total light transmittance (Tt) representing the total amount of light transmitted through the light diffusing film 102 and the diffused light transmittance (Td) diffused and transmitted by the light diffusing film 102. From the ratio to the following formula (1):
Total haze (%) = (Td / Tt) × 100 (1)
Is required.

  The total light transmittance (Tt) is the sum of the parallel light transmittance (Tp) and the diffused 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 according to JIS K 7361.

  The “internal haze” of the light diffusion film 102 is a haze other than the haze (surface haze) caused by the surface shape of the light diffusion layer 106 among all the hazes.

  When the total haze and / or internal haze is less than 30%, the light scattering property is insufficient, and it is difficult to obtain a sufficient wide viewing angle performance. Further, when the total haze and / or internal haze exceeds 70%, light scattering becomes strong, and the front contrast may be lowered when the light diffusing polarizing plate is applied to the liquid crystal display device. Further, when the total haze and / or internal haze exceeds 70%, the transparency of the light diffusion film 102 tends to be impaired. The total haze and internal haze are each preferably 35% or more and 65% or less.

  Specifically, the total haze, internal haze, and surface haze of the light diffusion film 102 are measured as follows. That is, first, in order to prevent warping of the film, the light diffusion film 102 is pasted on the glass substrate using an optically transparent adhesive so that the light diffusion layer 106 becomes the surface. In combination, a measurement sample is prepared, and the total haze value of the measurement sample is measured. The total haze value is determined by using a haze transmittance meter (for example, a haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7136, and a total light transmittance (Tt) and diffused light transmission. The rate (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 surface of the light diffusion layer 106 using glycerin, and the haze is measured in the same manner as the measurement of the total haze described above. Since the surface haze resulting from the surface shape of the surface on the light emission side of the surface of the light diffusion layer 106 is almost canceled by the bonded triacetyl cellulose film, the haze is “ It can be regarded as “internal haze”. Therefore, the “surface haze” of the light diffusion film 102 is expressed by the following formula (2):
Surface haze (%) = Total haze (%)-Internal haze (%) (2)
More demanded.

  The light diffusion film 102 may have another layer (including an adhesive layer) between the transparent base film 105 and the light diffusion layer 106.

  Next, a method for manufacturing the light diffusion film 102 will be described. The light diffusion film 102 can be formed by a method including a step of applying a resin liquid in which the translucent fine particles 106b are dispersed on the transparent base film 105.

  The resin liquid is a translucent fine particle 106b, a translucent resin 106a constituting the light diffusion layer 106, or a resin forming the same (for example, ionizing radiation curable resin, thermosetting resin, thermoplastic resin, or metal alkoxide). And other components such as a solvent as necessary. In the case where an ultraviolet curable resin is used as the resin forming the translucent resin 106a, the resin liquid includes a photopolymerization initiator (radical polymerization initiator). Examples of the photopolymerization initiator include acetophenone photopolymerization initiator, benzoin photopolymerization initiator, benzophenone photopolymerization initiator, thioxanthone photopolymerization initiator, triazine photopolymerization initiator, and oxadiazole photopolymerization initiator. An initiator or the like is used. Examples of the photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2 '-Biimidazole, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, benzyl, 9,10-phenanthrenequinone, camphorquinone, methyl phenylglyoxylate, titanocene compound and the like can also be used. The usage-amount of a photoinitiator is 0.5-20 weight part normally with respect to 100 weight part of resin contained in a resin liquid, Preferably, it is 1-5 weight part. In order to make the optical properties and the surface shape of the light diffusion film 102 uniform, the dispersion of the light-transmitting fine particles 106b in the resin solution is preferably isotropic dispersion.

  Application of the resin liquid onto the transparent substrate film 105 can be performed by, for example, a gravure coating method, a micro gravure coating method, a rod coating method, a knife coating method, an air knife coating method, a kiss coating method, a die coating method, or the like. . 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 transparent substrate film 105 (the surface on the light diffusion layer 106 side) for the purpose of improving the coating property of the resin liquid or improving the adhesion to 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 (easy adhesion layer) may be formed on the transparent base film 105, and the resin liquid may be applied on the other layer.

  In order to improve the adhesion between the transparent substrate film 105 and the polarizing film 101, the surface of the transparent substrate film 105 opposite to the surface on the light diffusion layer 106 side is subjected to the surface treatment as described above. It is preferable.

  The light diffusion film 102 is a method in which a resin liquid in which translucent fine particles 106b are dispersed is applied onto a transparent substrate film 105, and then a mirror surface or an uneven surface of a mold is transferred to the surface of the layer made of the resin liquid. Can also be formed. For example, a light diffusion layer having a flat surface as shown in FIG. 1 transfers 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. Can be formed. 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. It can be formed by transferring the uneven surface. 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 106a, 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 lamp, and a metal halide lamp are preferably used.

  Further, as the electron beam, 50 to 1000 keV emitted from various electron beam accelerators such as a cockroft Walton type, a bandegraph type, a resonance transformation type, an insulation core transformation type, a linear type, a dynamitron type, and a 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 diffusing film 102, the step of continuously feeding the transparent base film 105 wound in a roll shape, the translucent fine particles 106b are dispersed. It includes a step of applying a resin liquid and drying it as necessary, a step of curing a layer made of the resin liquid, and a step of winding up the obtained light diffusion film 102. Such a manufacturing method can be carried out using, for example, a manufacturing apparatus shown in FIG.

  First, the transparent base film 105 is continuously unwound by the unwinding device 301. Next, a resin liquid in which the translucent fine particles 106 b are dispersed is applied onto the unwound transparent base film 105 using the coating device 302 and the backup roll 303 facing the coating device 302. Next, when the solvent is contained in the resin liquid, the transparent substrate film 105 coated with the resin liquid is dried by passing it through the dryer 304. Next, the transparent base film 105 provided with a layer made of a resin liquid is a mirror surface metal roll or an embossing metal roll 305 between the nip roll 306 and the layer made of the resin liquid is a mirror surface 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, in a state where the transparent base film 105 is wound around the mirror surface metal roll or the embossing metal roll 305, the ultraviolet light is irradiated from the ultraviolet irradiation device 308 through the transparent base film 105, thereby removing from the resin liquid. The light diffusion layer 106 is formed by curing the layer. Since the irradiated surface becomes hot due to the 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 about 80 ° C. . Further, one or a plurality of ultraviolet irradiation devices 308 can be used. The transparent substrate 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 transparent 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 metal roll 305 for embossing, you may harden by irradiating an ultraviolet-ray.

  The light diffusion film 102 and the polarizing film 101 are bonded to each other through an adhesive layer or the like. The light diffusing film 102 also functions as a protective film for the polarizing film 101, and such a configuration is advantageous for reducing the thickness of the light diffusing polarizing plate. The bonding using the adhesive between the light diffusion film 102 and the polarizing film 101 is performed by the same method using the same adhesive as described later for the bonding between the surface treatment film 103 and the light diffusion film 102. Can do.

(Surface treatment film)
The surface treatment film 103 is a film in which one surface of the transparent resin film 107 is optically treated. Specifically, the surface treatment layer 108 having a desired optical function on one surface of the transparent resin film 107. It can be a film formed. As the transparent resin film 107, for example, a resin film made of a cellulose acetate resin such as TAC (triacetyl cellulose), an acrylic resin such as polymethyl methacrylate, a polycarbonate resin, and a polyester resin such as polyethylene terephthalate is used. be able to. The thickness of the transparent resin film 107 is, for example, 10 to 500 μm, and preferably 20 to 300 μm.

  As the surface treatment film 103, for example, the surface treatment layer 108 is an antiglare layer having irregularities on the surface that uses irregular reflection on the surface to reduce or prevent reflection on the display screen (that is, the above-mentioned optical treatment film 103). (Anti-glare treatment is an anti-glare film) or an anti-reflection layer that reduces or prevents reflection of external light incident on the display screen by the anti-glare film or surface treatment layer 108. There can be mentioned an antireflection film (that is, the optical treatment is an antireflection treatment).

  As the antiglare film, for example, after the ultraviolet curable resin composition containing or not containing fine particles is coated on the transparent resin film 107, the formed ultraviolet curable resin layer has a predetermined uneven surface shape. An ultraviolet curable resin composition containing fine particles on the transparent resin film 107, or an antiglare layer provided with predetermined surface irregularities by curing the ultraviolet curable resin layer while pressing the uneven surface of the mold. After the coating, a UV curable resin layer is cured without using a mold, and thus an antiglare layer having predetermined surface irregularities by fine particles can be used. A commercially available anti-glare film can also be used as the anti-glare film.

As the antireflection film, for example, a film having a low refractive index layer composed of a material lower than the refractive index of the light diffusion layer 106 as an antireflection layer, or a material higher than the refractive index of the light diffusion layer 106 is used. Examples thereof include a layer having a laminated structure of a high refractive index layer and a low refractive index layer made of a material lower than the refractive index of the high refractive index layer as an antireflection layer. The low refractive index layer is, 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 107 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.

(Adhesive layer, adhesive layer)
In the light diffusing polarizing plate of the present invention, the surface treatment film 103 is usually a surface opposite to the surface treatment layer 108 of the transparent resin film 107 (a surface on which the surface treatment film 103 is not subjected to optical treatment). Then, it is bonded to the light diffusion layer 106 of the light diffusion film 102 via the pressure-sensitive adhesive layer or the adhesive layer 104.

  A conventionally well-known thing can be used as an adhesive which forms an adhesive layer, For example, an acrylic adhesive, a urethane type adhesive, a silicone type adhesive etc. are mentioned. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer can be provided by a method in which such a pressure-sensitive adhesive is, for example, an organic solvent solution, which is applied onto the light diffusion layer 106 or the transparent resin film 107 by a die coater or a gravure coater and dried. The sheet-like pressure-sensitive adhesive formed on the release-treated plastic film (referred to as a separate film) can also be provided by a method of transferring to the light diffusion layer 106 or the transparent resin film 107. The thickness of the pressure-sensitive adhesive layer is usually in the range of 2 to 40 μm.

  Moreover, as an adhesive, since it can adhere | attach the surface treatment film 103 and the light-diffusion film 102 with high adhesive strength, without exerting a bad influence on the external appearance of a light-diffusion polarizing plate, the curable resin composition containing an epoxy resin An adhesive comprising an active energy ray such as a thermosetting resin composition or a water-based adhesive containing a polyvinyl alcohol resin or a urethane resin as an adhesive component can be preferably used. Among them, an adhesive made of a curable resin composition containing an epoxy resin is more preferably used because production efficiency can be improved such that a drying step is not required and good adhesive strength can be obtained.

  Bonding the surface treatment film 103 and the light diffusion film 102 using an adhesive made of a curable resin composition containing an epoxy resin is performed by applying the adhesive on the light diffusion layer 106 or the transparent resin film 107. Then, after laminating both films via an uncured adhesive layer, the film can be cured by irradiating with active energy rays or heating to cure the uncured adhesive layer. There are no particular limitations on the method of applying the adhesive, and various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Since each coating method has an optimum viscosity range, the viscosity of the adhesive may be adjusted using an organic solvent. The thickness of the adhesive layer after curing is usually 0.1 to 20 μm, preferably 0.2 to 10 μm, and more preferably 0.5 to 5 μm.

  Prior to the bonding with the adhesive or the adhesive, the bonding surface of the transparent resin film 107 and / or the light diffusion layer 106 is subjected to an easy adhesion process such as a corona discharge process or a primer process (formation of a primer layer). May be.

(Protective film)
As shown in FIGS. 1 and 2, the light diffusing polarizing plate of the present invention includes a protective film 109 laminated on the opposite side of the polarizing film 101 from the light diffusing film 102 via an adhesive layer or the like. May be. The protective film 109 is preferably a film made of a polymer having low birefringence and excellent transparency, mechanical strength, thermal stability, moisture shielding properties, and the like. Examples of such films include cellulose acetate resins such as TAC (triacetyl cellulose); acrylic resins; fluorine resins such as tetrafluoroethylene / hexafluoropropylene copolymers; polycarbonate resins; polyethylenes Polyester resins such as terephthalate; polyimide resins; polysulfone resins; polyethersulfone resins; polystyrene resins; polyvinyl alcohol resins; polyvinyl chloride resins; polyolefin resins or polyamide resins It is done. Among these, a triacetyl cellulose film and a norbornene-based thermoplastic resin film can be preferably used from the viewpoints of polarization characteristics and durability. The norbornene-based thermoplastic resin film is particularly suitable because it has high moisture and heat resistance and can greatly improve the durability of the polarizing plate and has high dimensional stability because of low hygroscopicity. For forming the resin into a film, a conventionally known method such as a casting method, a calendering method or an extrusion method can be used. Although there is no limitation in the thickness of the protective film 109, 500 micrometers or less are preferable from viewpoints, such as thickness reduction of a polarizing plate, More preferably, it is the range of 5-300 micrometers, More preferably, it is the range of 5-150 micrometers.

  The bonding using the adhesive between the polarizing film 101 and the protective film 109 can be performed by the same method using the same adhesive as described above for the bonding between the surface treatment film 103 and the light diffusion film 102. it can.

  Note that an optical compensation film such as a retardation film (retardation plate) or the like may be bonded to the polarizing film 101 instead of the protective film 109.

  The light diffusing polarizing plate having the above configuration is typically a glass substrate of a liquid crystal cell through an adhesive layer or the like so that the surface treatment film 103 is on the viewing side when applied to a liquid crystal display device. Is attached to the liquid crystal display 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. 4 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 of FIG. 4 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 the present invention 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.

  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. The light incident on the liquid crystal cell 401 is emitted from the liquid crystal cell 401 with the polarization state 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 the present invention, 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 conventionally transmitted. The light is further condensed by the light diffusing polarizing plate 405. This makes it possible to obtain an excellent image quality such as color reproducibility as compared with the conventional apparatus.

Hereinafter, the constituent members constituting the liquid crystal display device of the present invention will be described in more 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. Note that the backlight device 402 used in the present invention is not limited to the direct type shown in FIG. 4, 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 a flat surface type. Various types such as a shape light source type can be used.

[Light diffusion means]
As shown in FIG. 5, the light diffusing unit 403 includes a light diffusing plate 403 a disposed on the backlight device 402, and a front 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. 5, the light diffusion plate 403 a can be a film or 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 made of various acrylic resins, melamine resins, polyethylene resins, polystyrene resins, organic silicone resins, acrylic-styrene copolymer resins, and the like, 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, methacryl 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. In this specification, the “thickness of the light deflection plate” refers to the maximum thickness from the surface of the light deflection plate 403b close to the light diffusion plate 403a to the apex of the apex angle of the linear prism 450. Point to. In a portion where the thickness from the surface of the light deflecting plate 403b close to the light diffusing plate 403a to the top of the apex angle of the linear prism 450 is not maximum (for example, the valley portion of the linear prism 450), the light deflecting plate 403b. The thickness may not be in the above range.

  The light diffusing plate 403a and the light deflecting plate 403b may be formed integrally, 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. 6, the light diffusing unit 403 may be provided with a light diffusing function by dispersing and mixing a light diffusing agent 440 on a light deflecting plate 403 b that performs a light deflecting function.

  Further, as shown in FIG. 7, 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. 7, 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.

  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. Usually, as shown in FIG. 4, since the back surface of the light diffusing means 403 and the light incident surface of the liquid crystal cell 401 are arranged in parallel, the direction of 70 ° with respect to the normal line of the light incident surface of the liquid crystal cell 401 For example, as shown in FIG. 8, 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. 5 and 6) 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. 5 and 6) is usually in the range of 10 μm to 500 μm, and preferably in the range of 30 μm to 200 μm.

  As shown in FIG. 9, non-parallel light means that light emitted from a circle having a diameter of 1 cm on the exit surface of the light diffusing means 403 is parallel to the exit surface 1 m away from the normal direction of the exit 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)
As shown in FIG. 10, the liquid crystal display device of the present invention can include a retardation plate 406. In the liquid crystal display device 400 ′ shown in FIG. 10, the retardation plate 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 case where a retardation plate is disposed between the light diffusing polarizing plate 405 and the liquid crystal cell 401.

  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.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples. In addition, the measuring method of the haze of the light-diffusion film in the following examples, the thickness of a light-diffusion layer, and the weight average particle diameter of the used translucent fine particle is as follows.

(A) Haze Using an optically transparent adhesive, measurement was performed using a measurement sample in which a light diffusion film was bonded to a glass substrate on the base film side. For the measurement of the total haze value and the internal haze, a haze transmittance meter (haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd.) based on JIS K 7136 was used. Based on the result, the surface haze was calculated from the above formula (2).

(B) Thickness of light diffusing layer The thickness of the light diffusing film is measured using DIGIMICRO MH-15 (main body) and ZC-101 (counter) manufactured by NIKON, and the substrate thickness of 80 μm is subtracted from the measured layer thickness. Was used to measure the thickness of the light diffusion layer.

(C) Weight average particle diameter of light-transmitting fine particles 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).

[Production of metal roll]
(Production of metallic mirror 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 tester MIC10 (manufactured by Krautkramer).

(Production of metal emboss roll)
The surface of a 200 mm diameter iron roll (STKM13A by JIS) was prepared by applying copper ballad plating. Copper ballad plating consists of a copper plating layer / thin silver plating layer / surface copper plating layer, and the thickness of the entire plating layer was about 200 μm. The copper-plated surface is mirror-polished, and further, zirconia beads TZ-B125 (manufactured by Tosoh Corporation, average particle size: 125 μm) are used on the polished surface using a blasting device (manufactured by Fuji Seisakusho). Blasting was performed at a blast pressure of 0.05 MPa (gauge pressure, the same shall apply hereinafter) and a fine particle usage amount of 16 g / cm ² (a usage amount per 1 cm ² of surface area of the roll, the same shall apply hereinafter) to form irregularities on the surface. Using a blasting device (manufactured by Fuji Seisakusho) on the uneven surface, zirconia beads TZ-SX-17 (manufactured by Tosoh Corp., average particle size: 20 μm), blast pressure 0.1 MPa, using fine particles Blasting was performed at an amount of 4 g / cm ² to finely adjust the surface irregularities. The resulting copper-plated iron roll with unevenness was etched with a cupric chloride solution (etching amount: 3 μm). Then, chromium plating processing (thickness of chromium plating: 4 μm) was performed to produce a metal embossing roll. The Vickers hardness of the chromium plating surface of the obtained metal embossing roll was 1000 (the measuring method of Vickers hardness is the same as the above).

[Production of surface-treated film]
(Production Example 1: Production of antiglare film)
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.

  Next, with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition, “Lucillin TPO” (manufactured by BASF, chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) ) Was added, and diluted with propylene glycol monomethyl ether so that the solid content concentration was 60% by weight to prepare a coating solution.

This coating solution was applied on a transparent resin film which is a 80 μm thick triacetyl cellulose (TAC) film, and dried for 1 minute in a drier set at 80 ° C. The dried transparent resin film was pressed and adhered to the uneven surface of the metal embossing roll 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 transparent resin film side so that the amount of light in terms of h-line is 300 mJ / cm ² to cure the ultraviolet curable resin composition layer, and transparent An antiglare film having an antiglare layer formed on the resin film was obtained.

(Production Example 2: Production of antireflection film)
10 parts by weight of dipentaerythritol triacrylate, 10 parts by weight of pentaerythritol tetraacrylate, 30 parts by weight of urethane acrylate (“UA-306T” manufactured by Kyoeisha Chemical Co., Ltd.), “Irgacure 184” (manufactured by Ciba Japan Co., Ltd.) as a photopolymerization initiator ) 2.5 parts by weight, 50 parts by weight of methyl ethyl ketone and 50 parts by weight of butyl acetate as a solvent were mixed to prepare a coating liquid for forming a hard coat layer which is an ultraviolet curable resin composition. This coating solution was applied onto a transparent resin film (refractive index: 1.49), which is a TAC film having a thickness of 80 μm, with a wire bar coater and dried in a dryer set at 80 ° C. for 1 minute. A hard coat layer was formed on the transparent resin film after drying by irradiating with ultraviolet rays at a power of 120 W from a distance of 20 cm for 10 seconds using a metal halide lamp. The obtained hard coat layer had a thickness of 5 μm and a refractive index of 1.52.

Next, isopropyl alcohol and 0.1N hydrochloric acid were added to tetraethoxysilane and hydrolyzed to obtain a solution containing a tetraethoxysilane polymer composed of an oligomer. Antimony-doped tin oxide (ATO) fine particles having a primary particle diameter of 8 nm are mixed with this solution, and isopropyl alcohol is added to obtain 2.5 wt% of tetraethoxysilane polymer and 2.5 wt.% Of antimony-doped tin oxide fine particles. A coating solution for forming an antistatic layer containing 5% by weight was obtained. On the other hand, the TAC film on which the hard coat layer was formed was immersed in a 1.5N-NaOH aqueous solution at 50 ° C. for 2 minutes for alkali treatment, washed with water, and then washed with a 0.5 wt% H ₂ SO ₄ aqueous solution at room temperature. It was neutralized by dipping for 30 seconds, further washed with water, and dried. The antistatic layer-forming coating solution was applied onto the alkali-treated hard coat layer with a wire bar coater and dried in a drier set at 120 ° C. for 1 minute to form an antistatic layer. The resulting antistatic layer had a thickness of 163 nm, a refractive index of 1.53, and an optical film thickness of 250 nm.

  Next, an oligomer is formed by adding isopropyl alcohol and 0.1N hydrochloric acid to a 95: 5 (molar ratio) mixture of tetraethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane and hydrolyzing the mixture. A solution containing a polymer of an organosilicon compound was obtained. A coating solution for forming a low refractive index layer containing 2 wt% of an organosilicon compound and 2 wt% of low refractive index silica fine particles by mixing low refractive index silica fine particles having voids in the solution and adding isopropyl alcohol to the solution. Got. The obtained coating solution for forming a low refractive index layer was coated on the antistatic layer with a wire bar coater and dried in a dryer set at 120 ° C. for 1 minute to form a low refractive index layer. The obtained low refractive index layer had a thickness of 91 nm, a refractive index of 1.37, and an optical film thickness of 125 nm. As described above, an antireflection film comprising a hard coat layer, an antistatic layer and a low refractive index layer on a transparent resin film was produced.

[Production of light diffusion film]
(Production Example 3: Production of light diffusion film A)
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, 35 parts by weight of polystyrene-based particles having a weight average particle size of 6.0 μm and a standard deviation of 2.19 μm as translucent fine particles with respect to 100 parts by weight of the solid content of the ultraviolet curable resin composition, And 5 parts by weight of photopolymerization initiator “Lucirin TPO” (manufactured by BASF, chemical name: 2,4,6-trimethylbenzoyldiphenylphosphine oxide) so that the solid content concentration is 60% by weight. A coating solution was prepared by diluting with propylene glycol monomethyl ether.

This coating solution was applied onto a TAC film (transparent substrate film) having a thickness of 80 μm and dried for 1 minute in a dryer set at 80 ° C. The dried transparent substrate film was brought into close contact with the mirror surface of the metal mirror roll with a rubber roll so that the ultraviolet curable resin composition layer was on the roll side. In this state, the ultraviolet curable resin composition layer is cured by irradiating light from a high-pressure mercury lamp with an intensity of 20 mW / cm ² from the transparent substrate film side so as to be 300 mJ / cm ^{2 in} terms of the amount of h-line conversion, A light diffusion film A composed of a light diffusion layer having a flat surface and a transparent substrate film was obtained.

(Production Example 4: Production of light diffusion film B)
A light diffusion film B was produced in the same manner as in Production Example 3 except that the ultraviolet curable resin composition layer of the transparent base film after drying was cured without being brought into close contact with the mirror surface of the metal mirror roll.

  Table 1 shows the haze of the light diffusion films A and B, the thickness of the light diffusion layer, and the like.

<Example 1>
After the corona treatment is applied to the surface of the transparent base film of the light diffusion film A obtained in Production Example 3, an ultraviolet curable adhesive containing an ultraviolet curable epoxy resin and a cationic photopolymerization initiator is thickened on the corona treatment surface. Coating was performed at 4 μm. On the other hand, after a corona treatment was applied to one side of a TAC film (thickness 80 μm) as a protective film, the same UV curable adhesive as described above was applied to the corona treatment surface with a thickness of 4 μm. Next, the light diffusion film A is laminated on one surface of a polarizing film obtained by adsorbing and orienting iodine on a uniaxially stretched polyvinyl alcohol resin film, and the protective film is disposed on the other surface. It laminated | stacked through the adhesive bond layer, and was pinched with a pair of nip roll. Then, the ultraviolet-ray was irradiated from the protective film side, both the adhesive bond layers were hardened, and the light diffusable polarizing plate was obtained.

  Next, the antiglare film obtained in Production Example 1 is a general-purpose acrylic transparent so that the transparent resin film side becomes a bonding surface on the light diffusion layer of the light diffusion film A in the light diffusion polarizing plate. A light diffusing polarizing plate laminated with an adhesive and subjected to an antiglare treatment was obtained.

<Example 2>
Instead of the light diffusion film A, a light diffusing polarizing plate subjected to an antiglare treatment was obtained in the same manner as in Example 1 except that the light diffusion film B obtained in Production Example 4 was used.

<Example 3>
Instead of the antiglare film, a light diffusing polarizing plate subjected to an antireflection treatment was obtained in the same manner as in Example 1 except that the antireflection film obtained in Production Example 2 was used.

<Example 4>
Example 1 except that the light diffusion film B obtained in Production Example 4 was used instead of the light diffusion film A, and the antireflection film obtained in Production Example 2 was used instead of the antiglare film. In the same manner, a light diffusing polarizing plate that was subjected to antireflection treatment was obtained.

<Comparative Example 1>
By pressing the surface of the light diffusion layer of the light diffusion film A against the concavo-convex surface of the metal embossing roll with a rubber roll instead of the laminated body in which the light diffusion film A and the antiglare film are laminated via an adhesive layer. A light diffusing polarizing plate having an antiglare treatment was obtained in the same manner as in Example 1 except that a film having an antiglare treatment applied to the light diffusion layer was used.

<Comparative example 2>
Instead of the light diffusion film A, a light diffusing polarizing plate subjected to an antiglare treatment was obtained in the same manner as in Comparative Example 1 except that the light diffusion film B obtained in Production Example 4 was used.

<Comparative Example 3>
Instead of the laminate in which the light diffusion film A and the antireflection film are laminated via an adhesive layer, an antistatic layer is formed on the surface of the light diffusion layer of the light diffusion film A according to the method described in Production Example 2. By sequentially forming the low refractive index layer, a light diffusing polarizing plate that has been subjected to antireflection treatment in the same manner as in Example 3 is obtained except that the light diffusion layer is subjected to antireflection treatment. It was.

<Comparative example 4>
Instead of the light diffusion film A, a light diffusing polarizing plate that was subjected to antireflection treatment was obtained in the same manner as in Comparative Example 3 except that the light diffusion film B obtained in Production Example 4 was used.

(Evaluation of surface treatment characteristics of light diffusing polarizing plate)
(1) Evaluation of anti-glare property Anti-glare property was evaluated about the light diffusable polarizing plate of Examples 1-2 and Comparative Examples 1-2 by which the glare-proof process was performed. Specifically, the light diffusing polarizing plate was visually observed from the uneven surface (antiglare layer surface) side in a bright room with a fluorescent lamp to confirm the presence or absence of reflection of the fluorescent lamp. The case where the reflection of the fluorescent lamp was not observed over the entire surface of the film was A, and the case where the reflection of the fluorescent lamp was observed on at least a part of the film surface was indicated as B. The results are shown in Table 2.

(2) Evaluation of color unevenness Color unevenness was evaluated for the light diffusing polarizing plates of Examples 3 to 4 and Comparative Examples 3 to 4 subjected to the antireflection treatment. Specifically, a light-diffusing polarizing plate with the protective film surface colored black by a black matte spray is visually observed from the surface side of the low refractive index layer in a bright room with a fluorescent lamp to confirm the presence or absence of color unevenness. did. A case where no color unevenness was observed over the entire film surface was designated as A, and a case where color unevenness was observed on at least a part of the film surface was designated as B. The results are shown in Table 2. Color unevenness is a phenomenon in which the inside of the surface looks rainbow-colored in the above visual observation due to in-plane non-uniformity on the antireflection treatment surface. When such color unevenness occurs, the antireflection function is poor. It is judged that there is.

  As shown in Table 2, according to the light diffusable polarizing plate according to the present invention, it can be seen that excellent surface treatment characteristics can be imparted even to a light diffusion film that is difficult to be directly surface treated.

  100, 200, 405 Light diffusing polarizing plate, 101 Polarizing film, 102 Light diffusing film, 103 Surface treatment film, 104 Adhesive layer or adhesive layer, 105 Transparent substrate film, 106 Light diffusing layer, 106a Translucent resin , 106b Translucent fine particles, 107 transparent resin film, 108 surface treatment layer, 109 protective film, 301 unwinding device, 302 coating device, 303 backup roll, 304 dryer, 305 mirror surface metal roll or embossing metal Roll, 306 nip roll, 307 peeling roll, 308 ultraviolet irradiation device, 309 take-up device, 400, 400 ′ liquid crystal display device, 401 liquid crystal cell, 402 backlight device, 403 light diffusion means, 403a light diffusion plate, 403b, 403b ′ Optical deflection plate, 40 Backlight side polarizing plate, 406 retardation 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 (10)

A polarizing film;
A light diffusion film laminated on the polarizing film;
A surface-treated film that is laminated on the light diffusion film, and is subjected to optical treatment on one surface of the transparent resin film;
With
The light diffusion film has a light diffusion layer in which 20 to 100 parts by weight of light-transmitting fine particles are dispersed in the light-transmitting resin with respect to 100 parts by weight of the light-transmitting resin.
The light-diffusion polarizing plate by which the light-diffusion layer of the said light-diffusion film and the said surface treatment film are mutually bonded through the adhesive layer or the adhesive bond layer. The surface treatment film has a surface not subjected to optical treatment,
The light diffusion layer and the surface of the surface treatment film not subjected to optical treatment are bonded to each other via an adhesive layer or an adhesive layer, and the light diffusion layer and the surface treatment film are The light diffusable polarizing plate of Claim 1 currently bonded.   The surface treatment film is an antiglare film in which an antiglare treatment is performed on one surface of a transparent resin film, or an antireflection film in which an antireflection treatment is performed on one surface of a transparent resin film. Item 3. The light diffusing polarizing plate according to Item 1 or 2.   The said light-diffusion film is a light-diffusable polarizing plate in any one of Claims 1-3 provided with the transparent base film and the said light-diffusion layer laminated | stacked on the said transparent base film.   The light diffusing polarizing plate according to claim 4, wherein the light diffusing layer is formed by applying a resin liquid in which the translucent fine particles are dispersed on the transparent base film.   The light diffusion layer is formed by applying a resin liquid in which the translucent fine particles are dispersed on the transparent base film, and then transferring a mirror surface or an uneven surface of a mold onto the surface of the layer made of the resin liquid. The light diffusing polarizing plate according to claim 4, wherein the light diffusing polarizing plate is formed. 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 6, in this order,
The light diffusing polarizing plate is a liquid crystal display device arranged such that the polarizing film side faces the liquid crystal cell.   The light emitted from the light diffusing means has a light distribution characteristic in which the luminance in a direction inclined by 70 ° from the normal direction of the light incident surface of the liquid crystal cell is 20% or less with respect to the luminance in the normal direction. The liquid crystal display device according to claim 7, comprising non-parallel light.   The liquid crystal display device according to claim 7, wherein the light diffusing unit includes a light diffusing plate and a light deflecting plate in this order from the backlight device side.   The liquid crystal display device according to claim 7, wherein the liquid crystal cell is any one of a TN liquid crystal cell, an IPS liquid crystal cell, and a VA liquid crystal cell.

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