WO2007072856A1

WO2007072856A1 - Light diffusing sheet and light diffusing plate, and backlight unit and liquid crystal display device using them

Info

Publication number: WO2007072856A1
Application number: PCT/JP2006/325374
Authority: WO
Inventors: Kazuhisa Hirata
Original assignee: Nippon Shokubai Co., Ltd.
Priority date: 2005-12-21
Filing date: 2006-12-20
Publication date: 2007-06-28
Also published as: TW200730886A

Abstract

This invention provides a light diffusing sheet comprising a transparent film and a light diffusing layer provided on at lest one side of the transparent film, the light diffusing layer comprising a group of at least one type of fine particles dispersed in a light transparent resin, characterized in that the absolute value of the difference in refractive index between the light transparent resin constituting the light diffusing layer and the group of at least one type of fine particles is not less than 0.05; a light diffusing plate characterized by comprising a transparent support and a light diffusing layer provided on at least one side of the transparent support, the light diffusing layer comprising a group of at least one type of fine particles dispersed in a light transparent resin, the absolute value of the difference in refractive index between the light transparent resin constituting the light diffusing layer and the group of at least one type of fine particles being not less than 0.05; and a light diffusing plate characterized by comprising a light diffusing sheet applied onto at least one side of the transparent support with the aid of an adhesive or a pressure-sensitive adhesive, the light diffusing sheet comprising a transparent film and a light diffusing layer provided on one side of the transparent film and formed of a group of at least one type of fine particles dispersed in a light transparent resin, the absolute value of the difference in refractive index between the light transparent resin constituting the light diffusing layer and the group of at least one type of fine particles being not less than 0.05. The light diffusing sheet and light diffusing plates, while maintaining basic optical properties such as excellent light diffusing properties and light focusing properties and, at the same time, high total light transmittance and brightness, can reduce the members of a backlight unit and, at the same time, is excellent in scratch resistance of the light diffusing layer, and thus is suitable for used in a backlight unit in a liquid crystal display device.

Description

Light diffusing sheet and light diffusing plate, and backlight unit and liquid crystal display device using the same

Technical field

The present invention relates to a light diffusing sheet and a light diffusing plate, and a backlight unit and a liquid crystal display device using the same.

Background art

[0002] Currently, liquid crystal display devices are used in a wide range of fields such as cellular phones, PDA terminals, digital cameras, televisions, personal computer displays, and notebook computers. In a liquid crystal display device, for example, a backlight unit is disposed behind a liquid crystal display panel, and an image is displayed by supplying light from the knock light unit to the liquid crystal display panel. The backlight unit used in such a liquid crystal display device is required to supply as much light as possible without simply supplying uniform light to the liquid crystal display panel in order to make the displayed image easy to see. In other words, the knocklight unit is required to have optical characteristics such as excellent light diffusibility and high brightness.

For example, as shown in FIG. 20, in the conventional backlight unit, in addition to the light source 201, light emitted backward from the light source 201 is directed to a liquid crystal display panel (not shown) (hereinafter referred to as “front direction”). ) Reflecting sheet 202 that plays a role of reflecting light); a light diffusing plate 203 that diffuses light from the light source 201 (line light source) to form a surface light source and erase the shape of the light source; Light that has passed through the light diffusing plate 203 is further diffused, the shape of the light source is erased, and the light is condensed in the front direction to improve the brightness. A number of members such as a prism sheet 205 which plays a role of concentrating the light in the front direction and improving the luminance are also configured. In the knocklight unit 200 of FIG. 20, the force that shows one light diffusion sheet and one prism sheet each. Usually, the knocklight unit has a plurality of light diffusion sheets and prism sheets in order to obtain high brightness. Used.

Here, as shown in FIG. 21, for example, the conventional light diffusing plate is a transparent thermoplastic resin 21 such as polymethyl methacrylate, MS resin, polycarbonate, and cyclic polyolefin. A composition obtained by kneading a fine particle group 212 such as a silicone-based resin or an acrylic-based resin in 1 is extruded into a plate shape or cast and used. The light diffusion plate 210 shown in FIG. 21 diffuses light by the fine particle group 212 dispersed in the transparent thermoplastic resin 211. Further, in the conventional light diffusion sheet, for example, as shown in FIG. 22, the surface of a transparent film 221 such as a polyethylene terephthalate film is directly coated with a composition obtained by kneading the fine particle group 223 in the translucent resin 222. Things are used. In the light diffusing sheet 220 shown in FIG. 22, in the light diffusing layer 224, the light is diffused by the fine particles completely embedded in the translucent resin 222, and the fine particles partially protruded from the translucent resin 222. To collect the light in the front direction. Further, although not shown in the drawings, a conventional prism sheet is used in which a prism pattern of acrylic resin is uniformly and precisely formed on the surface of a polyester film, for example.

However, as the conventional backlight unit shown in FIG. 20 has a large number of members, the cost required for assembly increases. In addition, since light from the light source passes through many members before reaching the liquid crystal display panel, loss of light occurs, and total light transmittance and luminance are reduced. As a result, for example, in order to improve luminance, it is necessary to increase the number of light sources or increase the power of the light sources. Furthermore, when a plurality of prism sheets or light diffusion sheets are stacked in order to improve the brightness, there is a problem that moire caused by light interference between the sheets occurs and the image quality of the display image is lowered. Therefore, in the structure of the knock light unit, there is a need for a reduction in the number of members and a combination of functions without reducing the total light transmittance and brightness and without causing light interference.

[0006] As an attempt to reduce the number of members of the knocklight unit or to combine the functions, for example, a method of attaching a light diffusion sheet on a glass substrate serving as a light diffusion plate (for example, JP 2 005-129346), a method of using only a light diffusing sheet held on a transparent member without using a light diffusing plate (see, for example, JP-A-2003-272406), a prism sheet Instead, a method of forming prism rows on the surface of the light diffusing plate (see, for example, Japanese Patent Application Laid-Open No. 2003-016819), and bonding a resin sheet having a three-dimensional pattern such as a prism shape to the surface of the light diffusing plate Method (see, for example, Japanese Patent Application Laid-Open No. 2004-163575), a diffusion layer containing a diffuser is provided between a light incident control layer composed of a prism surface and a light distribution layer. (For example, refer to JP-A-2005-107020).

[0007] According to the methods described in JP-A-2005-129346 and JP-A-2003-272406, the light diffusing plate and the light diffusing sheet are respectively integrated, or the diffusing plate is omitted. Although it is an abbreviated method, sufficient diffused light cannot be obtained, so the shape of the light source cannot be completely erased, and since a prism sheet is not used, low brightness and power cannot be obtained. problem ^; a force ^s. In addition, the methods described in Japanese Patent Application Laid-Open Nos. 2003-0116819, 2004-163575, and 2005-107020 are all methods for integrating the light diffusing plate and the prism sheet. Force Brightness is improved and the shape of the light source can be completely erased. On the other hand, it is difficult to accurately form the prism shape on an industrial scale, resulting in an increase in manufacturing cost.

On the other hand, attempts to improve the light diffusibility and brightness of the light diffusing sheet are also actively made. As such an attempt, for example, a method in which a part of the fine particle group is completely embedded in the light diffusion layer formed on the transparent base film and the remaining part is partially embedded (for example, Japanese Patent Laid-Open No. 11 64611). See), a method of arranging spherical fine particles in a single layer on a translucent substrate (see, for example, Japanese Patent No. 3509703), and a method of embedding microsphere lenses in a light absorption layer formed on a transparent support substrate (For example, see JP-A-2001-281420).

[0009] However, the method described in JP-A-11 64611 is excellent in light diffusibility, but since there are few fine particles partially protruding from the light diffusion layer, the light collecting property is low and the luminance is low. In addition, the methods described in Japanese Patent No. 3509703 and Japanese Patent Application Laid-Open No. 2001-281420 are excellent in light-collecting properties, but only spherical particles and microsphere lenses are arranged in a single layer. Therefore, there is a problem that the light diffusibility is insufficient and the shape of the light source cannot be completely erased.

[0010] By the way, a light diffusion sheet provided with a light diffusion layer containing fine particles is in contact with other members with which the convex portions of the light diffusion layer come into contact during production, storage, transportation, installation on a display, and the like. By rubbing, scratches occur on the light diffusion sheet and the contact member. For example, the light diffusing sheet is stored in a roll shape, and at this time, the light diffusing layer is strongly pressed against the facing base film, so that the light diffusing sheet and the base film are damaged. Also on the display At the time of installation, an optical sheet such as a light diffusion sheet, a prism sheet, or a brightness enhancement sheet may be further installed on the light diffusion sheet. At that time, the convex portions of the light diffusion layer come into contact with the optical sheet, so that the light diffusion sheet and the optical sheet are damaged. As described above, when the light diffusing sheet is scratched, optical characteristics such as light diffusibility and total light transmittance are deteriorated.

[0011] As an attempt to improve the scratch resistance of the light diffusing sheet, for example, a method in which the light diffusing layer contains crosslinked (meth) acrylic acid ester polymer fine particles whose compression strength and average particle diameter are adjusted ( For example, see Japanese Patent No. 3531668), a method in which a light diffusing layer contains rosin particles and a particulate lubricant whose compressive strength is adjusted (see, for example, JP-A-2003-270410), a light diffusing sheet And a method of providing a sticking prevention layer composed of a resin layer containing a hard coat agent on the back surface of the base film on which the film is formed (see, for example, JP-A-2003-107219).

However, in the method described in Japanese Patent No. 3531668, since the crosslinked (meth) acrylate polymer fine particles are coated with a transparent resin binder, the fine particles partially protrude from the light diffusion layer. In some cases, the transparent resin binder covering the surface may be peeled off by friction or the like, and the method described in JP-A-2003-270410 uses a particulate lubricant in addition to the resin particles of the light diffusing agent. Therefore, the light diffusibility of the light diffusing layer may be lowered, and the method described in Japanese Patent Application Laid-Open No. 2003-107219 has a higher anti-sticking layer hardness than the light diffusing layer! 2H to 3H), there is a problem that even if it is possible to prevent scratches on the back surface of the base film on which the light diffusion layer is formed, scratches cannot be prevented from occurring on the light diffusion layer.

Disclosure of the invention

[0013] Under the circumstances described above, the problem to be solved by the present invention is that, in addition to being excellent in light diffusibility and light condensing property, high light transmittance and luminance can be obtained. While maintaining, the number of components of the knock light unit can be reduced, and the light diffusion sheet and light diffusion plate excellent in scratch resistance of the light diffusion layer, and the backlight unit and liquid crystal using them It is to provide a display device.

As a result of various studies, the present inventors have configured a light diffusion layer in a light diffusion sheet or a light diffusion plate. If the refractive index difference between the translucent resin and the fine particle group is defined, the light diffusion sheet and light diffusion plate are high by themselves and have light diffusibility and light condensing properties. Since it is not necessary to use a light diffusing sheet and a light diffusing plate or a prism sheet, the number of members can be reduced while maintaining the basic optical characteristics of the knock light unit, and inorganic If (meth) acrylic resin containing ultrafine particles or organic / inorganic composite ultrafine particles is used as a translucent resin, the hardened resin has an appropriate hardness derived from inorganic ultrafine particles or organic / inorganic composite ultrafine particles. Thus, the present invention was completed by finding that the light diffusing layer and the contact member are less likely to be damaged by covering the light diffusing agent fine particles partially protruding from the light diffusing layer.

That is, the present invention is a light diffusing sheet in which a light diffusing layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on at least one surface of a transparent film, Provided is a light diffusing sheet characterized in that the absolute value of the difference in refractive index between the translucent resin constituting the layer and at least one kind of fine particle group is 0.05 or more.

In a preferred embodiment, at least one of the light diffusing layers includes two types of fine particle groups, and the surface roughness of the light diffusing layer is an arithmetic average roughness of not less than 0 and not more than 7 m. . In addition, a light diffusion layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on one surface of the transparent film, and at least one kind of the translucent resin is formed on the light diffusion layer. A condensing layer in which fine particle groups are embedded is formed, and the surface roughness of the condensing layer is not less than 0.5 μm and not more than 7 μm in terms of arithmetic average roughness. Alternatively, a light diffusion layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one side of the transparent film, and at least one kind of transparent resin is provided on the opposite surface of the transparent film. A light collecting layer in which fine particle groups are embedded is formed, and the surface roughness of the light collecting layer is not less than 0 and not more than 7 m in terms of arithmetic average roughness. Furthermore, the translucent resin is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles.

[0017] Further, according to the present invention, a light diffusing layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on at least one surface of the transparent support, and the light transmissive layer constituting the light diffusing layer is formed. A light diffusing plate characterized in that the absolute value of the difference in refractive index between the hydrophobic resin and at least one kind of fine particle group is 0.05 or more; and at least the transparent resin on one side of the transparent film. 1 type A light diffusing sheet in which a light diffusing layer in which fine particles are dispersed is bonded to at least one surface of a transparent support with an adhesive or a pressure-sensitive adhesive, and constitutes the light diffusing layer. There is provided a light diffusing plate characterized in that an absolute value of a refractive index difference with at least one kind of fine particle group is 0.05 or more.

In a preferred embodiment, at least one of the light diffusing layers contains two types of fine particle groups, and the surface roughness of the light diffusing layer is not less than 0 and not more than 7 m in terms of arithmetic average roughness. Further, a light diffusion layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on one surface of the transparent support, and at least one type of translucent resin is formed on the light diffusion layer. A light condensing layer in which fine particle groups are embedded is formed, and the surface roughness of the light condensing layer is an arithmetic average roughness of not less than 0 and not more than 7 m. Alternatively, a light diffusion layer in which at least one type of fine particle group is dispersed in a transparent resin is formed on one side of the transparent support, and at least 1 of the transparent resin is provided on the opposite surface of the transparent support. A condensing layer in which various kinds of fine particle groups are embedded is formed, and the surface roughness of the condensing layer is not less than 0. Alternatively, a light diffusing layer in which at least one type of fine particle group is dispersed in a transparent resin is formed on one side of the transparent support, and at least 1 of the transparent resin is provided on one side of the transparent film. A condensing sheet having a condensing layer in which various kinds of fine particle groups are embedded is attached to the opposite surface of the transparent support with an adhesive or an adhesive, and the surface roughness of the condensing layer is an arithmetic average. The roughness is 0.5 μm or more and 7 μm or less. Alternatively, on one side of the transparent film, a light diffusion layer in which at least one kind of fine particle group is dispersed is formed in the translucent resin, and on the light diffusion layer, at least one kind of fine particle group is formed in the translucent resin. A light diffusing sheet formed with a light condensing layer embedded therein is bonded to one side of the transparent support with an adhesive or an adhesive, and the surface roughness of the light condensing layer is an arithmetic average roughness of 0. This is 7 m or less. Alternatively, a light diffusing sheet in which a light diffusing layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one side of a transparent film is attached to one side of the transparent support with an adhesive or a pressure sensitive adhesive. And a condensing layer in which at least one kind of fine particle group is embedded in a transparent resin is formed on the opposite surface of the transparent support, and the surface roughness of the condensing layer is an arithmetic average roughness of 0. It is 5 μm or more and 7 μm or less. Alternatively, a light diffusion layer in which a light diffusion layer in which at least one type of fine particle group is dispersed in a transparent resin is formed on one side of a transparent film A light-condensing layer in which a sheet is bonded to one side of the transparent support with an adhesive or a pressure-sensitive adhesive, and a light-condensing layer in which at least one type of fine particle group is embedded in one side of the transparent film. A sheet is attached to the opposite surface of the transparent support with an adhesive or an adhesive.

And the surface roughness of the light condensing layer is not less than 0 and not more than 7 m in terms of arithmetic average roughness. Furthermore, the translucent resin is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles.

[0019] Further, the present invention provides a backlight unit comprising a light source, a reflection sheet, a transparent support, and the light diffusion sheet; a light source, a reflection sheet, and the light diffusion sheet; A backlight unit comprising a light source, a reflective sheet, and the light diffusing plate; and a backlight unit comprising any of these backlight units! A liquid crystal display device characterized by the above.

[0020] According to the light diffusing sheet and the light diffusing plate of the present invention, the shape of the light source can be completely erased, and the line light source can be used as a surface light source. Therefore, the light diffusing property and the light collecting property are excellent. When high light transmittance and brightness can be provided, the number of components of the knock light unit can be reduced while maintaining basic optical characteristics. Therefore, the knock light unit and the liquid crystal display device of the present invention using such a light diffusion sheet and light diffusion plate can reduce the cost of various products using the liquid crystal display device. Moreover, since the loss of light rays when passing between members is reduced by reducing the number of members, the number of light sources can be reduced and the power of the light sources can be reduced. Furthermore, since the number of members does not cause light interference between sheets, the image quality of the display image is improved. Since the light diffusing layer has excellent scratch resistance, the light diffusing sheet and light diffusing plate of the present invention are easy to handle during production, storage, transportation, use, etc., and yield is improved. .

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view showing a configuration example of a light diffusion sheet of the present invention.

FIG. 2 is a schematic sectional view showing another configuration example of the light diffusion sheet of the present invention.

FIG. 3 is a schematic cross-sectional view showing another configuration example of the light diffusion sheet of the present invention.

FIG. 4 is a schematic sectional view showing another configuration example of the light diffusion sheet of the present invention. FIG. 5 is a schematic cross-sectional view showing another configuration example of the light diffusion sheet of the present invention.

FIG. 6 is a schematic cross-sectional view showing another configuration example of the light diffusion sheet of the present invention.

FIG. 7 is a schematic cross-sectional view showing a configuration example of a light diffusion plate of the present invention.

FIG. 8 is a schematic cross-sectional view showing another configuration example of the light diffusion plate of the present invention.

FIG. 9 is a schematic cross-sectional view showing another configuration example of the light diffusion plate of the present invention.

FIG. 10 is a schematic sectional view showing another configuration example of the light diffusing plate of the present invention.

FIG. 11 is a schematic cross-sectional view showing another configuration example of the light diffusion plate of the present invention.

FIG. 12 is a schematic cross-sectional view showing another configuration example of the light diffusion plate of the present invention.

FIG. 13 is a schematic cross-sectional view showing another configuration example of the light diffusion plate of the present invention.

FIG. 14 is a schematic sectional view showing another configuration example of the light diffusing plate of the present invention.

FIG. 15 is a schematic explanatory view showing a configuration example of a backlight unit of the present invention.

FIG. 16 is a schematic explanatory view showing another configuration example of the backlight unit of the present invention.

FIG. 17 is a schematic explanatory view showing another configuration example of the backlight unit of the present invention.

FIG. 18 is a schematic explanatory diagram showing another configuration example of the backlight unit of the present invention.

FIG. 19 is a drawing-substituting photograph showing irregularities on the surface of the light collecting layer of the light diffusion sheet obtained in Example 1.

FIG. 20 is a schematic explanatory view showing a configuration example of a conventional backlight unit.

FIG. 21 is a schematic cross-sectional view showing a configuration of a conventional light diffusing plate.

FIG. 22 is a schematic sectional view showing a configuration example of a conventional light diffusion sheet.

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] << Light diffusion sheet >>

The light diffusion sheet of the present invention is a light diffusion sheet in which a light diffusion layer in which at least one kind of fine particle group is dispersed is formed on at least one surface of a transparent film. The absolute value of the difference in refractive index between the translucent resin constituting the layer and at least one kind of fine particle group is 0.05 or more.

In a preferred embodiment, at least one of the light diffusion layers contains two types of fine particle groups, and the surface roughness of the light diffusion layer is not less than 0 and not more than 7 m in terms of arithmetic average roughness. . Further, on one side of the transparent film, at least one kind of fine particle group in translucent resin A light-diffusing layer is formed, and a light-condensing layer is formed on the light-diffusing layer by embedding at least one kind of fine particles in a translucent resin, and the surface of the light-condensing layer is roughened. The arithmetic mean roughness is 0.5 μm or more and 7 μm or less. Alternatively, a light diffusion layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one side of the transparent film, and at least one kind of transparent resin is provided on the opposite surface of the transparent film. A light collecting layer in which fine particle groups are embedded is formed, and the surface roughness of the light collecting layer is not less than 0 and not more than 7 m in terms of arithmetic average roughness. Furthermore, the translucent resin is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles.

Here, in the light diffusion layer, “at least one kind of fine particle group is dispersed in the light transmissive resin” means that one kind of fine particle is contained in the light transmissive resin constituting the light diffusion layer. Force that groups are dispersed substantially uniformly, force that two types of particles are dispersed substantially uniformly, or group of three or more types of particles are distributed substantially uniformly Means that. In the case of the type of fine particle group, it is preferable that substantially all of the fine particle group is embedded in the light-transmitting resin constituting the light diffusion layer, and there are two or more types of fine particle groups. Preferably, a fine particle group (for example, a fine particle group having a relatively small particle diameter) mostly embedded in the light transmissive resin constituting the light diffusion layer and a part of the light transmissive resin constituting the light diffusion layer In particular, there are fine particle groups that protrude (for example, fine particle groups having a relatively large particle diameter). However, when two or more types of fine particle groups with a sufficiently large difference in particle size are used, the particle size is small! / ヽ particle group has a large particle size! Also present in translucent resin. The type of fine particle group is distinguished depending on the material and the state of existence, but it is not distinguished depending on the particle diameter and shape. In addition, in the light collecting layer, “at least one kind of fine particle group is embedded in the translucent resin” means that the fine particle group (for example, having a particle diameter of the light transmitting resin constituting the light collecting layer) is embedded. A relatively small particle group) and a group of fine particles partially protruding from the translucent coagulant constituting the light collecting layer (for example, a particle group having a relatively large particle diameter). means.

[0025] Such a light diffusion sheet is, for example, the content of the fine particle group in the translucent resin and the difference in refractive index between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group. , The shape of each fine particle constituting the fine particle group dispersed in the light diffusion layer, the average particle diameter of the fine particle group, In addition, the surface roughness of the light condensing layer, the shape of each fine particle constituting the fine particle group embedded in the light condensing layer, the average particle diameter of the fine particle group, and the embedded state (or partially protruding state) should be adjusted. Thus, the light diffusibility of the light diffusion layer and the light condensing property of the light collecting layer can be controlled. Further, as a preferred embodiment, in the case of a light diffusion layer in which two types of fine particle groups are dispersed in a translucent resin, the surface roughness of the light diffusion layer, that is, the fine particle groups dispersed in the translucent resin. By adjusting the embedding state (or partially protruding state) of the fine particles constituting the light diffusion layer, the light diffusibility and the light condensing property of the light diffusion layer can be controlled. That is, if two types of fine particle groups are dispersed in the translucent resin constituting the light diffusing layer and the surface roughness of the light diffusing layer is adjusted, the light diffusing layer having the light diffusing property can be focused. Can be granted. Hereinafter, such a light diffusion layer may be referred to as a “light diffusion / condensing layer”.

For example, the greater the difference in refractive index between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group, the more light is refracted at the interface between the translucent resin and each fine particle, It can be diffused sufficiently. Therefore, in the light diffusing sheet of the present invention, in order to express the degree of light diffusibility of the fine particle group in the light diffusing layer, the refractive index of the translucent resin constituting the light diffusing layer and at least one kind of fine particle group. The absolute value of the difference is specified to be 0.05 or higher. When the absolute value of the refractive index difference is less than 0.05, light is not largely refracted at the interface between the translucent resin and each fine particle constituting at least one kind of fine particle group, and the light cannot be sufficiently diffused. Therefore, the shape of the light source cannot be completely erased, and the function of making the line light source a surface light source may not be provided. The absolute value of the refractive index difference is preferably 0.07 or more, more preferably 0.09 or more. The upper limit of the absolute value of the refractive index difference is not particularly limited, but is preferably 2.0 or less, more preferably 1.5 or less. The refractive index of the translucent resin was measured by forming a 40 m thick film and measuring the refractive index of the obtained film with a multiwavelength Abbe refractometer (for example, DR-M2, manufactured by Atago Co., Ltd.). Value. However, the measurement wavelength is 589.3 nm and the measurement temperature is 25 ° C. For the refractive index of the fine particle group, several types of Cargill standard refraction liquids (for example, standard series, manufactured by Moritex Co., Ltd .; refractive index range n ²⁵ = 1. 300-2.11) are prepared. Of fine particles in the standard refractive liquid

D

Immersion and transmission optical microscope at 25 ° C (for example, digital microscope VHX-200, manufactured by Keyence Corporation; light source lamp is a 12V, 100W halogen lamp (color temperature 3, 100K ( When the maximum amount of light is observed)))), the interface between the fine particle group and the refractive standard solution is the least visible! The refractive index of the standard refractive solution used at times is used. However, if there are two types of standard refractive liquids used when the interface between the fine particle group and the standard refractive liquid is least visible, the refractive index of the fine particle group is the intermediate value of these refractive indexes. If the refractive index of the fine particle group is outside the refractive index range of the standard gilding liquid, the refractive index of the material is taken as the refractive index of the fine particle group.

[0027] Preferably, as an embodiment, when two kinds of fine particle groups are dispersed in the light diffusion layer, the fine particle group dispersed in the translucent resin is composed of the fine particle group mostly embedded in the light diffusion layer and the light. It consists of a group of fine particles partially protruding from the diffusion layer. The latter fine particle group is partially embedded in the light diffusion layer, and the remaining portion protrudes from the light diffusion layer force. Part). Therefore, in the light diffusing sheet of the present invention, the surface roughness of the light diffusing layer is preferably expressed by arithmetic average roughness in order to express the embedded state (or partially protruding state) of the fine particle group in the light diffusing layer. 0. It is specified as 7 m or less. When the surface roughness is less than 0.5 / zm in terms of arithmetic average roughness, the fine particle group is unlikely to partially protrude from the light diffusion layer, and thus light may not be sufficiently collected. Conversely, if the surface roughness exceeds 7 m in terms of arithmetic average roughness, the fine particle group partially protrudes from the light diffusion layer, so that light may not be sufficiently collected. The surface roughness is more preferably 0.

It is 6 μm or less, more preferably 0.9 μm or more and 5 μm or less. The surface roughness is obtained by measuring the arithmetic average roughness at 5 or more points randomly selected for each sample using a surface roughness meter (for example, Dektak3030, manufactured by Nippon Vacuum Technology Co., Ltd.). It is the average value of the measured values.

[0028] Further, preferably U, as an embodiment, when two kinds of fine particle groups are dispersed in the light diffusion layer, the average particle diameter in the light diffusion layer is large! Expressed in a different form, the ratio of the layer thickness to the average particle diameter of the fine particle group in the light diffusion layer (layer thickness of the light diffusion layer Z average particle diameter of the fine particle group in the light diffusion layer) is Preferably it is 1.0 or more and 4.0 or less. When the ratio is less than 1.0, the fine particle group partially protrudes excessively from the light diffusion layer, so that light may not be sufficiently collected. Conversely, if the ratio exceeds 4.0, the group of fine particles is unlikely to partially protrude from the light diffusion layer. The light may not be collected sufficiently. The ratio is more preferably 1.05 or more and 3.0 or less, and still more preferably 1.1 or more and 2.5 or less. The average particle size of the fine particle group is a volume average particle size measured using a particle size distribution measuring device (for example, Multisizer II type, manufactured by Coulter, Inc.). The layer thickness of the light diffusion layer is obtained by measuring the layer thickness at 5 points or more for each sample using a thickness measuring instrument (for example, dial thickness gauge G-6, manufactured by Ozaki Mfg. Co., Ltd.). The average value of the measured values. Here, the layer thickness of the light diffusing layer refers to the thickness up to the maximum height portion where the back surface translucent resin exists where the light diffusing layer is in contact with the transparent film or the like. Therefore, for example, when the fine particle group is coated with a translucent resin, the maximum height portion is the most protruding part from the light diffusion layer among the fine particle group coated with the translucent resin. It refers to the apex of the translucent resin covering the fine particles.

[0029] Furthermore, as a preferred embodiment, in the case where a light condensing layer is provided in addition to the light diffusion layer, the fine particle group embedded in the translucent resin in the light condensing layer is buried in the light condensing layer. The latter fine particle group is partially embedded in the condensing layer and the remaining part is in a state where the condensing layer force protrudes. Light is condensed by the protruding part (convex part). Therefore, in the light diffusing sheet of the present invention, the surface roughness of the light condensing layer is preferably expressed as an arithmetic average roughness in order to express the embedded state (or partially protruding state) of the fine particle groups in the light condensing layer. As stated above, it is specified as 7 m or less. When the surface roughness is less than 0.5 m in terms of arithmetic average roughness, the fine particle group is unlikely to partially protrude from the light condensing layer, so that light may not be sufficiently collected. On the other hand, if the surface roughness exceeds 7 m in terms of arithmetic average roughness, the fine particle group partially protrudes excessively from the light condensing layer, so that light may not be sufficiently condensed. The surface roughness is an arithmetic average roughness, more preferably 0.7 μm or more and 6 μm or less, and still more preferably 0.9 μm or more and 5 μm or less. The surface roughness was obtained by measuring the arithmetic average roughness at 5 or more locations randomly selected for each sample using a surface roughness meter (Dektak3030, manufactured by Nippon Vacuum Technology Co., Ltd.). This is the average value of the measured values.

[0030] Furthermore, as a preferred embodiment, in the case where a light condensing layer is provided in addition to the light diffusion layer, the embedded state (or partially protruding state) of the fine particle group in the light condensing layer can be expressed in another form. Ratio of layer thickness to average particle diameter of fine particle group in condensing layer (concentration layer thickness Z condensing The average particle diameter of the fine particle group in the layer is preferably 1.0 or more and 4.0 or less. When the ratio is less than 1.0, the fine particle group partially protrudes from the light condensing layer, so that the light may not be sufficiently collected. On the other hand, when the ratio exceeds 4.0, the fine particle group is unlikely to partially protrude from the light condensing layer, so that the light may not be sufficiently collected. The ratio is more preferably 1.05 or more and 3.0 or less, and still more preferably 1.1 or more and 2.5 or less. The average particle size of the fine particle group is a volume average particle size measured using a particle size distribution measuring device (for example, Multisizer II type, manufactured by Coulter, Inc.). The layer thickness of the condensing layer is the average of the measured values obtained by observing the cross section of the light diffusion sheet with an electron microscope and measuring the layer thickness at 5 or more points for each sample. Here, the layer thickness of the condensing layer refers to the thickness up to the maximum height where the condensing layer is in contact with the light diffusing layer, the transparent film, etc., and the rear force translucent resin is present. Therefore, for example, when the fine particle group is coated with a translucent resin, the maximum height portion is the most part of the fine particle group coated with the translucent resin from the light collecting layer. The apex of the translucent resin that covers the protruding fine particles. For example, in the case of a light diffusion sheet in which a light condensing layer is formed on the surface of the transparent film and a light diffusion layer is formed on the back surface of the transparent film, the film is first formed at the stage where only the light condensing layer is formed. By measuring the total thickness of the transparent film and the light condensing layer with a thickness meter and subtracting the film thickness of the transparent film, the layer thickness of the light condensing layer can be calculated.

Hereinafter, the “surface (front surface)” of the transparent film means the surface of the obtained light diffusion sheet facing the liquid crystal display panel (front direction) when used, for example, The other side is expressed as “back side (back side)”, but it is not necessary to distinguish the front side from the back side when handling transparent film. If one side is the front side, the other side becomes the back side. There is no other special meaning.

[0032] <Translucent resin>

In the light diffusing sheet of the present invention, each of the light diffusing layer and the light collecting layer is composed of a translucent resin and at least one kind of fine particle group. The translucent resin constituting the light diffusion layer and the translucent resin constituting the light condensing layer may be the same type or different types.

[0033] Examples of the translucent resin include (meth) acrylic resin; styrene resin; vinyl acetate. Olefins such as polyethylene and polypropylene; Cyclic olefins such as norbornene resin; salt vinyl resin; salt vinylidene resin; polyethylene terephthalate and polyethylene Polyester-based resin such as naphthalate; copolymers of these

And so on. These rosins may be used alone or in combination of two or more. Of these, the (meth) acrylic resin is preferred.

[0034] In a preferred embodiment, the translucent resin constituting the light diffusion layer is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles. Here, “organic-inorganic composite ultrafine particles” means composite ultrafine particles in which an organic polymer is fixed on the surface of inorganic ultrafine particles. The term “ultrafine particles” is an expression for distinguishing from at least one type of fine particles dispersed in a translucent resin, and as will be described below, the average particle size is smaller than that of the latter type of fine particles. Small! / Dark means fine particles.

[0035] Of the (meth) acrylic resin used as a translucent resin, a repeating unit derived from a (meth) acrylic acid ester having a cycloalkyl group and a repeating element derived from isobutyl (meth) acrylate Group power consisting of units and repeating units derived from t-butyl (meth) acrylate. Preferred is a copolymer having at least one repeating unit selected and derived from a (meth) acrylic acid ester having a cycloalkyl group. A copolymer having a repeating unit is particularly preferred.

[0036] The repeating unit derived from the (meth) acrylic acid ester having a cycloalkyl group is preferably the following formula (1):

[0037] [Chemical 1]

[In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom, a methyl group or an ethyl group, R ³ is an organic residue, m is an integer of 0 or more and 4 or less. N is an integer of 0 or more and 2 or less, and when m is 2 or more and 4 or less, R ² may be the same or different. When n is 2, R ³ may be the same or different.]

Indicated by

In the above formula (1), the organic residue represented by R ³ is, for example, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, 1 or more carbon atoms, 5 or less hydroxy alkyl group, 1 or more carbon atoms, 5 or less alkoxyalkyl group, 1 or more carbon atoms, 5 or less acetooxyalkyl group, 1 to 5 carbon atoms halogenated (for example, chlorinated, bromine Or a fluorinated alkyl group. Among these organic residues, an alkyl group having 1 or more and 4 or less carbon atoms, a hydroxyalkyl group having 1 or more and 2 or less carbon atoms, an alkoxyalkyl group having 1 or more and 2 or less carbon atoms, 1 or more carbon atoms, Less than 2 acetooxyalkyl groups are preferred.

In the above formula (1), when n is 2, a ring may be formed by two R ³ . For example, a ring may be formed by two R ³ , and the cyclohexyl group in the above formula (1) may be an isoborn group. Further, the bonding position of R ^{3 to} the cyclohexyl group is not particularly limited, but when n is 1 or 2, preferably one R ³ is cycl. It binds to the 3rd or 4th position of the mouth hexyl group.

[0041] The repeating unit represented by the above formula (1) is not particularly limited. For example, cyclohexyl (meth) acrylate, cyclohexyl methyl (meth) acrylate, cyclohexyl ethyl ( (Meth) acrylate, cyclohexyl propyl (meth) acrylate, cyclohexyl butyl (meth) acrylate, 4-methylcyclohexyl methyl (meth) acrylate, 4-ethyl cyclohexylmethyl (meth) acrylate, isobornyl (meta ) It can be introduced by using monomers such as acrylate and 4-hydroxymethylcyclohexylmethyl (meth) acrylate. Of these monomers, cyclohexyl (meth) acrylate, cyclohexyl methyl (meth) acrylate, and 4-methylcyclohexyl methyl (meth) acrylate are preferred. That is, the repeating unit represented by the above formula (1) is preferably such that R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom, an R ³ cate group, m force ^ or 1 And n is 0 or 1.

[0042] The copolymer used as the translucent resin may contain a repeating unit derived from isobutyl (meth) acrylate. The repeating unit derived from isobutyl (meth) acrylate is “—CH—CH (COOCH CH (CH)) —” or “—CH—C (CH) (C

2 2 3 2 2 3

OOCH CH (CH)) — ”means a repeating unit. (Meth) acrylic acid iso

2 3 2

When a copolymer containing a repeating unit derived from butyl is used, heat resistance, moisture resistance, hardness and the like of the light diffusion layer and the light collecting layer are improved.

[0043] The copolymer used as the translucent resin may contain a repeating unit derived from t-butyl (meth) acrylate. The repeating unit derived from t-butyl (meth) acrylate means “one CH-CH (COOC (CH)) one” or “one CH-C (CH) (COOC (C

2 3 3 2 3

H)) means a repeating unit represented by “1”. Derived from t-butyl (meth) acrylate

3 3

When a copolymer containing a repeating unit is used, the heat resistance, moisture resistance, hardness, etc. of the light diffusion layer and the light collecting layer are improved.

[0044] The copolymer used as the translucent resin is preferably a repeating unit derived from a (meth) acrylic acid ester having a cycloalkyl group, a repeating unit derived from isobutyl (meth) acrylate, or It has at least one repeating unit derived from t-butyl (meth) acrylate. [0045] The copolymer used as the translucent resin may contain other repeating units! Monomers that can be used to synthesize the copolymer include, for example, polymerizable unsaturated monomers having a carboxyl group such as (meth) acrylic acid, maleic acid, and maleic anhydride; methyl (meth) atari Rate, ethyl (meth) acrylate, propyl (meth) acrylate, isopyl pill (meth) acrylate, butyl (meth) acrylate, 2-ethyl hexyl (meth) acrylate, lauryl (meth) acrylate , (Meth) acrylic acid alkyl esters such as stearyl (meth) acrylate; 2 hydroxyethyl (meth) acrylate, 4 hydroxy butyl (meth) acrylate, force prolatatone modified hydroxy (meth) acrylate, etc. Polyunsaturated unsaturated monomer: bull sulfonic acid, styrene sulfonic acid, sulfoethyl (meth) alk Polymerizable unsaturated monomers having a sulfonic acid group, such as relate; 2- (meth) attaroyloxychetyl acid phosphate, 2- (meth) allyloyloxypropyl acid phosphate, 2-methacryloyloxyschetilphe -Acidic phosphate ester unsaturated unsaturated monomers such as luric acid; Polymerizable unsaturated monomers having an epoxy group such as glycidyl (meth) acrylate; (meth) acrylamide, N, N'-dimethyl Polymerizable unsaturated monomers having a nitrogen atom such as aminoethyl (meth) acrylate; Polymerizable unsaturated monomers having a halogen atom such as salty bubul and salty vyuryidene; styrene, α-methyl Aromatic polymerizable unsaturated monomers such as styrene and butyl toluene; vinyl esters such as butyl acetate; vinyl ethers; (meth) acrylonitrile Unsaturated Shiani 匕合 of like; and the like. Other monomers to be used and their blending amounts may be determined in consideration of characteristics such as heat resistance, translucency and hardness desired for the translucent resin.

[0046] The content of each repeating unit in the copolymer used as the translucent resin is not particularly limited. In order to effectively prevent stagnation of the light diffusion sheet, preferably, a repeating unit derived from a (meth) acrylic acid ester having a cycloalkyl group in the copolymer and a repeating unit derived from isobutyl (meth) acrylate The total amount of units and repeating units derived from t-butyl (meth) acrylate is preferably 5.0% by mass or more and 90.0% by mass or less, more preferably 30% by mass relative to the polymerizable unsaturated monomer. It is 0 mass% or more and 8 0.0 mass% or less.

[0047] The method for producing the copolymer may be appropriately selected according to the type of monomer and the working environment. There is no particular limitation.

[0048] The translucent resin has a glass transition temperature of preferably 0 ° C or higher and 120 ° C or lower, more preferably

It is 10 ° C or more and 110 ° C or less, more preferably 20 ° C or more and 100 ° C or less. The glass transition temperature is calculated using the formula for FOX:

[0049] [Equation 1]

/ Tg-X CVV / Tg,)

[0050] [wherein Tg is the glass transition temperature (K) of the translucent resin, W is the mass fraction of monomer i, and Tg is the glass transition temperature of the resin composed of the monomer ( K)]

The glass transition temperature (K) calculated in (1) can be calculated by converting from absolute temperature (K) to Celsius temperature (° c).

[0051] The translucent resin has a haze of preferably 0% or more and 20% or less, more preferably 0% or more, 10% or less, further preferably 0% or more and 5% or less, and Z or The total light transmittance is preferably 70% or more and 100% or less, more preferably 80% or more and 100% or less. The haze and total light transmittance are values measured by a measurement method based on JIS K7105 using a turbidimeter (for example, NDH-1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0052] In a preferred embodiment, the translucent resin contains inorganic ultrafine particles and organic-inorganic composite ultrafine particles. Either one of inorganic ultrafine particles or organic-inorganic composite ultrafine particles may be used, or both may be used in combination. If the translucent resin contains inorganic ultrafine particles or organic-inorganic composite ultrafine particles, the heat resistance of the light diffusing layer and the condensing layer is improved, the deformation of the light diffusing layer due to heat is suppressed, and the liquid crystal display panel Luminance unevenness on the display screen is eliminated. In addition, when the translucent resin contains inorganic ultrafine particles or organic-inorganic composite ultrafine particles, the translucent resin has an appropriate hardness and toughness, so that the light diffusing sheet and the contact member are caused by friction with other members. Excellent scratch resistance, easy to handle during manufacturing, storage, transportation, use, etc., improving yield. Furthermore, it is possible to prevent the fine particle group from falling off the light diffusion sheet.

[0053] The material of the inorganic ultrafine particles is not particularly limited. For example, a metal element

(In the present invention, it is assumed that silicon is included.) Is a metal oxide that forms a three-dimensional network mainly through oxygen atoms. As a metal element constituting a metal oxide In the short-period element periodic table, metal elements belonging to Group 2 to Group 6 are preferred. Metal elements belonging to Group 3 to Group 5 are more preferred. -Kay, which is particularly preferred, is most preferred. As the inorganic ultrafine particles, colloidal silica is particularly preferable among the oxides of silicon.

[0054] The inorganic ultrafine particles may be formed of a single material or may be formed of two or more kinds of materials, and may be formed of one kind of fine particle cartridge having the same material. There are also two or more types of fine particle forces that are made of different materials.

[0055] Examples of the shape of the inorganic ultrafine particles include a spherical shape, a needle shape, a plate shape, a scale shape, and a crushed shape. The inorganic ultrafine particles having these shapes may be used alone or in combination of two or more.

[0056] The organic-inorganic composite ultrafine particles are composite ultrafine particles in which an organic polymer is fixed on the surface of the inorganic ultrafine particles. By fixing the organic polymer on the surface of the inorganic ultrafine particles, the dispersibility of the inorganic ultrafine particles in the translucent resin and the affinity between the translucent resin and the inorganic ultrafine particles are improved. The total light transmittance of the light diffusion layer and the light collecting layer is improved. Here, “fixing” means that a chemical bond is formed between the inorganic ultrafine particles and the organic polymer, which is not simply adhesion or adhesion. Therefore, when the organic / inorganic composite ultrafine particles are washed with an arbitrary organic solvent, substantially no organic polymer is detected in the organic solvent. The inorganic ultrafine particles may contain an organic polymer in the fine particles. In this case, moderate softness and toughness can be imparted to the central portion of the inorganic ultrafine particles.

[0057] The organic polymer means a polymer composed of organic components, and is not particularly limited with respect to molecular weight, shape, composition, presence or absence of functional groups, and the like. Examples of the resin constituting the organic polymer include (meth) acrylic resin; styrene resin; vinyl acetate resin; polyolefin resin such as polyethylene and polypropylene; and cyclic olefin resins such as norbornene resin. Examples thereof include resin, salt-bulle resin, salt-vinyl-redene resin, polyester resin such as polyethylene terephthalate, and copolymers thereof. These resins may be used alone or in combination of two or more. These resins may be partially modified with a functional group such as an amino group, an epoxy group, a hydroxyl group, or a carboxyl group. In addition The organic polymer content in the organic / inorganic composite ultrafine particles is preferably 0.5% by mass or more and 50% by mass or less with respect to the inorganic ultrafine particles, for example.

[0058] The average particle diameter of the inorganic ultrafine particles or organic-inorganic composite ultrafine particles is preferably 5 nm or more and 1 OO nm or less, more preferably 5 nm or more and 50 nm or less. If the average particle size is less than 5 nm, the surface energy of the fine particles becomes high and aggregation or the like may occur easily. Conversely, when the average particle diameter exceeds 200 nm, the amount of light passing through the light diffusion layer and the light condensing layer is decreased, and the luminance may be decreased. The average particle size of inorganic ultrafine particles and organic-inorganic composite ultrafine particles is a volume average particle size measured using a submicron particle size analyzer (NICOMP MODEL 370, manufactured by Nozaki Sangyo Co., Ltd.).

[0059] The content of the inorganic ultrafine particles or organic-inorganic composite ultrafine particles in the translucent resin is, for example, preferably 1 part by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the translucent resin. More preferably, it is 5 parts by mass or more and 100 parts by mass or less. If the content of inorganic ultrafine particles or organic-inorganic composite ultrafine particles is less than 1 part by mass, thermal deformation of the light diffusion layer and damage to the light diffusion layer and the contact member may not be sufficiently prevented. Conversely, if the content of inorganic ultrafine particles or organic inorganic composite ultrafine particles exceeds 200 parts by mass, it becomes difficult to coat the light diffusing layer, and the amount of light passing through the light diffusing layer and the condensing layer decreases. In addition, the total light transmittance and brightness may decrease.

[0060] The translucent resin may contain a polyfunctional isocyanate compound. When a polyfunctional isocyanate compound is contained and a component having a hydroxyl group is further contained, a crosslinked structure can be formed between the multifunctional isocyanate compound and the component having a hydroxyl group. As a result, the characteristics such as moisture resistance, flexibility and durability of the light diffusion layer and the light collecting layer are further improved.

[0061] In addition, additives such as a stabilizer, a deterioration preventing agent, a plasticizer, a dispersant, and a fluorescent brightening agent may be added to the translucent resin. The blending amount of these additives is not particularly limited as long as it is appropriately adjusted according to the type thereof.

[0062] <Fine particle group>

In the light diffusing sheet of the present invention, the light diffusing layer is composed of a translucent resin and at least one kind of fine particle group. In a preferred embodiment, the light diffusion on the transparent film And a condensing layer, both of which are composed of translucent resin and at least one kind of fine particle group. In this case, at least one type of fine particle group dispersed in the translucent resin constituting the light diffusion layer and at least one type of fine particle group embedded in the translucent resin constituting the light collecting layer are: Even if they are composed of the same kind of fine particles, they may be composed of different kinds of microparticle forces.

[0063] The material of each fine particle constituting the fine particle group includes, for example, (meth) acrylic resin such as polymethyl methacrylate; styrene resin such as polystyrene; amino compound such as melamine and benzoguanamine and formaldehyde Condensed with amino formalin crosslinked resin; polyurethane resin; polyester resin; silicone resin; fluorine resin; copolymers of these; clays such as smectite and kaolinite Inorganic compounds such as silica, titanium dioxide, alumina, silica alumina, zirconium oxide, zinc oxide, barium oxide, strontium oxide; calcium carbonate, barium carbonate, barium chloride, barium sulfate, barium nitrate, water Barium oxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium sulfate, And the like; silica composite 榭脂 particles of transparent or translucent 榭脂 and silica fine particles; strontium, strontium hydroxide, inorganic fine particles such as glass particles. Among these materials, as the material of each fine particle constituting at least one kind of fine particle group dispersed in the translucent resin constituting the light diffusion layer, (meth) acrylic resin, styrene resin, Amino-formalin crosslinked resin, silicone resin, silica, titanium, alumina, inorganic acid such as zinc oxide, calcium carbonate, barium sulfate, etc. are suitable, (meth) acrylic resin Fats, styrene-based resins, amino-based formalin crosslinked resins, silicone-based resins, titers, alumina, zinc oxide, calcium carbonate, and barium sulfate are particularly suitable. In addition, as the material of each fine particle constituting at least one kind of fine particle group embedded in the translucent resin constituting the light collecting layer, (meth) acrylic resin, styrene resin, amino formalin are used. Cross-linked resin, silicone-based resin, silica composite resin particles and the like are suitable, and (meth) acrylic resin, styrene-based resin, silicone-based resin, and silica composite resin particles are particularly preferable.

[0064] At least one type of fine particle group dispersed in the light transmissive resin constituting the light diffusion layer and at least one type of fine particle group embedded in the light transmissive resin constituting the light collecting layer are formed. Each fine particle may be made of a single material or two or more kinds of materials, and the fine particles may be made of different materials even if they are composed of the same kind of fine particle force 2 More than one kind of fine particle force is also configured.

[0065] Examples of the shape of each fine particle constituting the fine particle group include a spherical shape, a plate shape, an ellipsoid shape, a saddle shape, a polygonal shape, a disk shape, a star shape, a surface wrinkle shape, a hollow shape, and a crushed shape. It is done. The fine particles having these shapes may be used alone or in combination of two or more. Of the fine particles having these shapes, spherical particles are preferred as the fine particles constituting at least one kind of fine particle group dispersed in the translucent resin constituting the light diffusion layer, but stronger than the spherical particles.ヽ Light diffusibility. Addition of a small amount makes it excellent in light diffusibility and high!から When plate-shaped, ellipsoidal, bowl-shaped, polygonal, disk-shaped, star-shaped, surface wrinkled, hollow, crushed, etc. are suitable because total light transmittance and brightness can be obtained There is also. From the viewpoint of photofluorescence, spherical particles are particularly preferable as the fine particles constituting at least one kind of fine particle group embedded in the translucent resin constituting the light collecting layer.

[0066] The average particle size of the fine particle group dispersed in the translucent resin constituting the light diffusion layer is preferably 0.2 μm or more and 30 μm or less, more preferably 0.25 μm or more, 30 It is not more than μm, more preferably not less than 0 and not more than 10 m. If the average particle size of the fine particle group is less than 0, the light incident on the light diffusion layer may not be sufficiently diffused. Conversely, when the average particle size of the fine particle group exceeds 30 m, the amount of light passing through the light diffusion layer decreases, and the total light transmittance and luminance may decrease. The average particle size of the fine particle group is a volume average particle size measured using a particle size distribution measuring apparatus (for example, Multisizer II type, manufactured by Coulter Co., Ltd.).

[0067] The average particle size of the fine particle group embedded in the translucent resin constituting the light collecting layer is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 40 μm or less. More preferably, it is 5 μm or more and 30 μm or less. If the average particle size of the fine particle group is less than 1 μm, the light incident on the condensing layer may not be sufficiently collected. Conversely, when the average particle size of the fine particle group exceeds 50 m, the amount of light passing through the condensing layer may decrease, and the total light transmittance and luminance may decrease. The average particle size of the fine particle group is a volume average particle size measured using a particle size distribution measuring device (for example, Multisizer I type II, manufactured by Coulter, Inc.). [0068] The content of the fine particle group in the translucent resin constituting the light diffusion layer is, for example, preferably 1 part by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the translucent resin. Preferably they are 5 to 200 mass parts. When the content of the fine particle group is less than 1 part by mass, the light incident on the light diffusion layer may not be sufficiently diffused. On the contrary, if the content of the fine particle group exceeds 300 parts by mass, it becomes difficult to form a light diffusion layer, or the amount of light passing through the light diffusion layer decreases, and the total light transmittance and luminance may decrease. is there.

[0069] The content of the fine particle group in the translucent resin constituting the light collecting layer is, for example, preferably 5 parts by mass or more and 700 parts by mass or less with respect to 100 parts by mass of the translucent resin. Preferably they are 10 to 500 mass parts. When the content of the fine particle group is less than 5 parts by mass, the light incident on the condensing layer may not be sufficiently collected. On the contrary, when the content force of the fine particle group exceeds S700 parts by mass, it becomes difficult to form a condensing layer, or the amount of light passing through the condensing layer decreases, and the total light transmittance and luminance decrease. There is.

[0070] In a preferred embodiment, at least one of the light diffusion layers contains two types of fine particle groups. In this case, examples of the material of each fine particle constituting the fine particle group include the above-described materials listed as materials for each fine particle constituting the fine particle group in the light diffusion sheet of the present invention. Among these materials, a fine particle group that satisfies the condition that the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group is 0.05 or more (hereinafter referred to as “fine particle” The material of each fine particle constituting “Group A”) may be (meth) acrylic resin, styrene resin, amino formalin cross-linked resin, silicone resin, silica, titanium Inorganic acids such as alumina and acid zinc, calcium carbonate, and barium sulfate are preferred. (Meth) acrylic resin, styrene resin, amino formalin cross-linked resin, silicone resin Fat, titer, alumina, calcium carbonate, and barium sulfate are particularly suitable. Further, it is not always necessary to satisfy the condition that the absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group is 0.05 or more. Group B ”) may be made of (meth) acrylic resin, styrene resin, amino formalin cross-linked resin, silicone resin, silica composite resin particle (Meth) acrylic resin, styrene resin, silicone resin, and silica composite resin particles are particularly preferable. [0071] Each fine particle constituting the fine particle groups A and B may be formed of a single material or two or more kinds of material particles. The same material may be composed of one kind of fine particle cover, or may be composed of two or more kinds of fine particles of different materials.

[0072] Examples of the shapes of the fine particles constituting the fine particle groups A and B include the shapes described above as the shapes of the fine particles constituting the fine particle group in the light diffusion sheet of the present invention. The fine particles having these shapes may be used alone or in combination of two or more. Among the fine particles having these shapes, the fine particles constituting the fine particle group A are preferably spherical particles, but have a light diffusibility stronger than that of the spherical particles, and are excellent in light diffusibility when added in a small amount. In addition, high total light transmittance and brightness can be obtained, and thus irregular particles such as plate, ellipsoid, saddle, polygon, disk, star, surface wrinkle, hollow, and crushed are preferable. In some cases. The fine particles constituting the fine particle group B are particularly preferably spherical particles from the viewpoint of collecting light.

[0073] The average particle size of the fine particle group A is preferably 0.2 m or more and 30 μm or less, more preferably 0.25 μm or more and 20 μm or less, and still more preferably 0.3 μm or more, 10 μm or less. If the average particle size of the fine particle group A is less than 0.2 m, the light incident on the light diffusion layer may not be sufficiently diffused. On the contrary, when the average particle size of the fine particle group A exceeds 30 m, the amount of light passing through the light diffusion layer decreases, and the total light transmittance and luminance may decrease. The average particle size of the fine particle group A is a volume average particle size measured using a particle size distribution measuring device (for example, Multisizer II type, manufactured by Coulter, Inc.).

[0074] The average particle size of the fine particle group B is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 40 μm or less, and further preferably 5 μm or more and 30 μm or less. is there. If the average particle size of the particle group B is less than 1 μm, the light incident on the light diffusion layer may not be sufficiently collected. On the contrary, if the average particle size of the fine particle group B exceeds 50 m, the amount of light passing through the light diffusion layer may decrease, and the total light transmittance and luminance may decrease. The average particle size of the fine particle group B is a volume average particle size measured using a particle size distribution measuring device (for example, Multisizer II type, manufactured by Coulter Co., Ltd.).

[0075] The content of the fine particle group A in the translucent resin constituting the light diffusion layer is, for example, translucent The amount is preferably 1 part by mass or more and 300 parts by mass or less, more preferably 5 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the synthetic resin. If the content of the fine particle group A is less than 1 part by mass, the light incident on the light diffusion layer may not be sufficiently diffused. Conversely, if the content of fine particle group A exceeds 300 parts by mass, it becomes difficult to form a light diffusing layer, or the amount of light passing through the light diffusing layer decreases, resulting in a decrease in total light transmittance and luminance. There is.

[0076] The content of the fine particle group B in the translucent resin constituting the light diffusion layer is, for example, preferably 5 parts by mass or more and 700 parts by mass or less with respect to 100 parts by mass of the translucent resin. More preferably, it is 10 parts by mass or more and 500 parts by mass or less. If the content of the fine particle group B is less than 5 parts by mass, the light incident on the light diffusion layer may not be sufficiently collected. Conversely, if the content of fine particle group B exceeds 700 parts by mass, it becomes difficult to form a light diffusing layer, or the amount of light passing through the light diffusing layer decreases, resulting in a decrease in total light transmittance and luminance. There is.

[0077] <Light diffusion layer>

The light diffusion sheet of the present invention has a light diffusion layer in which at least one kind of fine particle group is dispersed in a translucent resin. The light diffusion layer has a function of sufficiently diffusing incident light.

[0078] In a preferred embodiment of the light diffusion sheet of the present invention, a light diffusion layer in which one kind of fine particle group is dispersed in a transparent resin is formed on at least one side of a transparent film. These fine particle groups are the fine particle group A satisfying the condition that the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group is 0.05 or more. . The fine particle group A is preferably mostly buried in a translucent resin constituting the light diffusion layer, and has a function of sufficiently diffusing the light incident on the light diffusion layer. The light diffusing layer formed on at least one side of the transparent film is composed of a translucent resin in which the fine particle group A is dispersed and has a function of sufficiently diffusing incident light. When the light diffusion layer is formed on the surface of the transparent film, the light that has entered and passed through the transparent film enters the light diffusion layer, and the light diffusion layer is formed on the surface of the transparent film. Can be sufficiently diffused. Further, when the light diffusion layer is formed on both surfaces of the transparent film, the light incident on the light diffusion layer formed on the back surface of the transparent film is sufficiently diffused by the particle group A in the light diffusion layer. The light enters the transparent film, passes through, enters the light diffusion layer formed on the surface of the transparent film, and is further sufficiently diffused by the fine particle group A. In addition, like this When using a light diffusion sheet in which one type of fine particle group is dispersed in the translucent resin constituting the light diffusion layer, two or more types of fine particles are used in the translucent resin constituting the light diffusion layer. It is desirable to use a light diffusion sheet in which the child groups are dispersed or a conventionally known light diffusion sheet in combination.

[0079] In the light diffusing sheet of the present invention, in a preferred embodiment, a light diffusing layer in which one kind of fine particle group is dispersed in a transparent resin is formed on the surface of the transparent film, and the light diffusing layer is formed. A condensing layer in which one type of fine particle group is embedded in the translucent coagulant is formed, or one type of fine particle group is dispersed in the translucent coagulant on the back surface of the transparent film. The light diffusing layer is formed, and a light condensing layer is formed on the surface of the transparent film by embedding one kind of fine particle group in a translucent resin. Among these fine particle groups, the fine particle group dispersed in the light diffusion layer has an absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group of 0.05 or more. It is a fine particle group A that satisfies the condition of being. The fine particle group A is preferably mostly buried in a translucent resin constituting the light diffusion layer, and has a function of sufficiently diffusing the light incident on the light diffusion layer. The light diffusing layer formed on the front or back surface of the transparent film is composed of a translucent resin in which the fine particle group A is dispersed, and has a function of sufficiently diffusing incident light. When the light diffusing layer is formed on the surface of the transparent film, the light that has entered and passed through the transparent film enters the light diffusing layer and is sufficiently diffused by the fine particle group A in the light diffusing layer. After that, the light is incident on the light collecting layer formed on the light diffusion layer. In addition, when the light diffusion layer is formed on the back surface of the transparent film, the light incident on the light diffusion layer is sufficiently diffused by the fine particle group A in the light diffusion layer, and then enters the transparent film. And enters the condensing layer formed on the surface of the transparent film.

[0080] The absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and the fine particle group A is 0.05 or more, preferably 0.07 or more, more preferably 0.09 or more. . The upper limit of the absolute value of the refractive index difference is not particularly limited, but is preferably 2.0 or less, more preferably 1.5 or less. Therefore, as the translucent resin and fine particle group A constituting the light diffusion layer, the translucent resin and fine particle group described above so that the absolute value of the difference in refractive index S falls within this range. Materials selected and combined as appropriate from the above are used in a blended amount adjusted as appropriate.

[0081] The thickness of the light diffusion layer is preferably 1 μm or more, 60 μm or less, more preferably 5 μm or more, 40 μm or less. If the thickness of the light diffusion layer is less than 1 μm, the light incident on the light diffusion layer may not be sufficiently diffused. Conversely, if the thickness of the light diffusing layer exceeds 60 m, the amount of light passing through the light diffusing layer decreases, and the total light transmittance and luminance may decrease.

[0082] The light diffusing layer may be formed of a single layer or may be formed of two or more layers. Also, the light diffusing layer may be formed of one single layer of the same material, but two types of materials are different. It may be composed of the above multiple layers.

[0083] In a preferred embodiment, the light diffusing sheet of the present invention has a light diffusing layer in which two or more kinds of fine particle groups are dispersed in a translucent resin on at least one side of a transparent film. These fine particle groups satisfy the above conditions when the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group is 0.05 or more. When the absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group is 0.05 or more, the fine particle group B does not necessarily have to satisfy the conditions. And. The fine particle group A is preferably mostly buried in the light-transmitting resin constituting the light diffusion layer and has a function of sufficiently diffusing the light incident on the light diffusion layer, whereas the fine particle group Preferably, most of B protrudes partially from the translucent resin constituting the light diffusing layer, and the front surface is a convex portion that partially protrudes the light sufficiently diffused by the fine particle group A. It has a function of collecting light in the direction. Therefore, such a light diffusion layer is sometimes referred to as “light diffusion layer”. The light diffusing light condensing layer formed on at least one side of the transparent film is composed of a translucent resin in which two or more kinds of fine particle groups A and B are dispersed, and sufficiently diffuses incident light. And has a function of condensing light in the front direction. Light diffusing 'If the condensing layer is formed on one side of the transparent film, the light that has entered the transparent film and passed through it is incident on the light diffusing' condensing layer and formed on the surface of the transparent film. In the diffusion-condensing layer, it is sufficiently diffused by the particle group A, and is condensed in the front direction by the convex part of the particle group B. In addition, when the light diffusion / condensation layer is formed on both sides of the transparent film, the light diffusion / condensation layer formed on the back surface of the transparent film is the light diffusion / condensation layer. The light is condensed by the convex part of B, and after being sufficiently diffused by the fine particle group A, it enters and passes through the transparent film, and enters the light diffusing 'condensing layer formed on the surface of the transparent film. Further, it is further sufficiently diffused by the fine particle group A, and the positive part of the fine particle group B is positive. It is condensed in the surface direction. The surface of the particle group B partially protruding from the light diffusing / condensing layer may or may not be covered with the light transmissive resin constituting the light diffusing / condensing layer. However, the viewpoint power for improving the scratch resistance of the light diffusion sheet is preferably covered. In either case, it is sufficient if the fine particle group B has light diffusion 'concavity and convexity formed on the surface of the condensing layer. Light diffusion' light incident on the condensing layer is formed on the surface of the light diffusion 'condensing layer. Concentrated in the front direction by the convex part of fine particle group B.

[0084] The absolute value of the difference in refractive index between the light transmissive resin and the fine particle group A constituting the light diffusing condensing layer is 0.

05 or more, preferably 0.07 or more, more preferably 0.09 or more. The upper limit of the absolute value of the refractive index difference is not particularly limited, but is preferably 2.0 or less, more preferably 1.5 or less. Therefore, the translucent resin and the fine particle group A constituting the light diffusing condensing layer have the absolute value of the difference in refractive index S. Materials appropriately selected and combined from the group of fats and fine particles are used in appropriately adjusted amounts.

[0085] The surface roughness of the light diffusing condensing layer is an arithmetic average roughness, preferably 0.5 / zm or more and 7 m or less, more preferably 0.7 m or more and 6 m or less, and still more preferably. 0.9 m or more and 5 m or less. Further, the ratio of the layer thickness to the average particle diameter of the fine particle group B in the light diffusion / condensing layer is preferably 1.0 or more and 4.0 or less, more preferably 1.05 or more and 3.0 or less, and further preferably. Is 1.1 or more and 2.5 or less. Therefore, the translucent resin and fine particle group B constituting the light diffusion / condensing layer are described above so that the ratio of the layer thickness to the average particle diameter and the surface roughness are within this range. A material selected and combined as appropriate from the translucent resin and the fine particle group is used by appropriately adjusting it within the range of the blending amount explained above.

[0086] The thickness of the light diffusion layer is preferably 1 μm or more and 60 m or less, more preferably 5 μm or more and 40 m or less. If the thickness of the light diffusion / condensing layer is less than 1 μm, light incident on the light diffusion / condensing layer may be sufficiently diffused and not collected. Conversely, if the thickness of the light diffusing / condensing layer exceeds 60 m, the amount of light passing through the light diffusing / condensing layer may decrease, and the total light transmittance and luminance may decrease.

[0087] The light diffusing condensing layer may be formed of a single layer or two or more layers. In addition, even if it is composed of one single layer of the same material, it may be composed of two or more layers of different materials.

Note that a layer having a refractive index different from that of the translucent resin may be formed on the fine particle group partially protruding from the light diffusing / condensing layer. Of the layers having different refractive indexes, a layer having a refractive index lower than that of the translucent resin is particularly preferable. Light diffusion · Total reflection at the interface between the fine particles partially protruding from the condensing layer and the layer having a low refractive index, and at the interface between the layer having a low refractive index and the air layer is reduced. Backward light scattering is reduced and total light transmission and brightness are improved.

[0089] In the light diffusing sheet of the present invention, the resin used as the light transmissive resin constituting the light diffusing layer or the light diffusing light collecting layer has an appropriate hardness and toughness. It has excellent scratch resistance with few scratches on the light diffusion sheet and contact member, and is easy to handle during production, storage, transportation, use, etc., and yield is improved.

[0090] <Condensing layer>

In a preferred embodiment, the light diffusing sheet of the present invention has a condensing layer in which at least one kind of fine particle group is embedded in a translucent coagulant. The condensing layer also has a light diffusing function that only condenses incident light in the front direction. When the light collecting layer is formed on the light diffusing layer formed on the surface of the transparent film, the light sufficiently diffused by the light diffusing layer is incident on the light collecting layer, and partially from the light collecting layer. It is condensed in the front direction by the fine particle group protruding to the front. When the condensing layer is formed on the surface of the transparent film, it is sufficiently diffused by the light diffusing layer formed on the back surface of the transparent film, then enters and passes through the transparent film, and enters the condensing layer. Thus, the light is collected in the front direction by the group of fine particles partially protruding from the light collecting layer. Note that the surface of the fine particle group partially protruding from the light collecting layer may or may not be covered with the translucent resin constituting the light collecting layer. In either case, it is sufficient if the group of fine particles embedded in the condensing layer forms irregularities on the surface of the condensing layer. Condensed in the front direction by the convex part.

[0091] The surface roughness of the light collecting layer is an arithmetic average roughness, and is preferably 0.5 / zm or more and m or less, more preferably 0.7 μm or more and 6 μm or less, and still more preferably 0. 9 μm or more and 5 μm or less. Further, the ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer is preferably Is 1.0 or more and 4.0 or less, more preferably 1.05 or more and 3.0 or less, and still more preferably 1.1 or more and 2.5 or less. Therefore, the translucent resin and the fine particle group constituting the condensing layer include the translucent resin described above so that the ratio of the layer thickness to the average particle diameter and the surface roughness are within this range. In addition, materials appropriately selected from the group of fine particles and combined can be appropriately adjusted and used within the range of the blending amounts described above.

[0092] The thickness of the light collecting layer is preferably 1 μm or more and 60 μm or less, more preferably 5 μm or more and 40 m or less. If the thickness of the condensing layer is less than 1 m, the light incident on the condensing layer may not be sufficiently collected. Conversely, if the thickness of the light condensing layer exceeds 60 m, the amount of light passing through the light condensing layer may decrease, and the total light transmittance and brightness may decrease.

[0093] The light-collecting layer may be formed of a single layer or may be formed of two or more layers, and the material may be different even if it is formed of one type of the same single layer. It may consist of more than one kind of multiple layers.

[0094] Note that a layer having a refractive index different from that of the translucent resin may be formed on the fine particle group partially protruding from the light collecting layer. Of the layers having different refractive indexes, a layer having a refractive index lower than that of the translucent resin is particularly preferable. Total reflection at the interface between the particle group partially protruding from the condensing layer and the layer having a low refractive index, and the interface between the layer having a low refractive index and the air layer is reduced. Light scattering is reduced and total light transmission and brightness are improved.

[0095] <Transparent film>

In the light diffusing sheet of the present invention, the transparent film is made of, for example, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate; a (meth) acrylic resin such as polymethyl methacrylate; 2- (hydroxyalkyl) acrylic Rataton ring-containing resins containing latatone ring structural units derived from acid esters; polycarbonate-based resins; olefin-based resins such as polyethylene and polypropylene; cyclic olefin-based resins such as norbornene resins; salt-bulls Examples thereof include fats; salty vinyl-redene-based resins; styrene-based resins; polyamide-based resins such as polyamide 6 and polyamide 66; cellulose derivatives such as triacetyl cellulose; and copolymers thereof. Of these materials, polyester-based resins, (meth) acrylic-based resins, outer ring-containing resins, and polycarbonate-based resins are suitable. In particular, polyethylene terephthalate, latton ring-containing resin, and polycarbonate resin are particularly suitable.

[0096] The transparent film may be formed of a single material or two or more kinds of materials, and may be formed of a single layer or a plurality of layers. Good

[0097] The thickness of the transparent film is preferably 5 μm or more and 500 μm or less, more preferably 10 μm or more and 400 μm or less, and further preferably 20 μm or more and 300 μm or less. If the thickness of the transparent film is less than 5 m, the mechanical strength of the light diffusing sheet may decrease. Conversely, if the thickness of the transparent film exceeds 500 m, the amount of light passing through the transparent film decreases, and the total light transmittance and brightness may decrease.

[0098] The transparent film preferably has a haze of 0% or more and 20% or less, more preferably 0% or more and 10% or less, still more preferably 0% or more and 5% or less, and Z or all light transmission. The rate is preferably 70% or more and 100% or less, more preferably 80% or more and 100% or less. The haze and total light transmittance are values measured by a measurement method based on JIS K7105 using a turbidimeter (for example, NDH-1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0099] Members that directly receive light of light source power, such as a transparent film or a light diffusion layer, may contain an ultraviolet inhibitor in these members in order to prevent the influence of ultraviolet rays. It is also possible to provide a UV protection layer on the surface that receives light from the light source, and members that come into contact with the air layer, such as transparent films, light diffusion layers, and condensing layers, are not affected by dust in the air. In order to prevent this, an antistatic agent may be contained in these members, or an antistatic layer may be provided on the surface in contact with the air layer.

[0100] Further, when the light diffusion layer and the light condensing layer or the light diffusion layer are formed on one side of the transparent film, the back surface of the transparent film is usually a smooth surface, but for example, embossing is performed. In addition, the light diffusing property may be a force imparting anti-sticking property, or a anti-sticking layer may be provided on the back surface of the transparent film. The anti-sticking layer is formed, for example, by directly coating the back surface of a transparent film with a composition obtained by kneading the above-described fine particle group in the above-described translucent resin. However, the average particle size of the fine particle group dispersed in the anti-sticking layer is preferably 0.5 μm or more and 20 μm or less, and more preferably. 1 μm or more and 15 m or less. The average particle size of the fine particle group is a volume average particle size measured using a particle size distribution measuring device (for example, Multisizer II type, manufactured by Coulter Co., Ltd.). The thickness of the anti-sticking layer is preferably 0.5 μm or more and 20 m or less, more preferably 1 m or more and 15 m or less. The content of the fine particle group in the translucent resin is not particularly limited, but is relatively small, and the fine particles constituting the fine particle group are separated from each other and dispersed in the translucent resin. However, it is sufficient that a part of the fine particle group partially protrudes from the translucent resin.

[0101] <Configuration example of light diffusion sheet>

Here, the specific structural example of the light-diffusion sheet of this invention is shown to FIGS. Note that FIG. 1 corresponds to a light diffusing sheet in which a light diffusing layer in which one kind of fine particle group is dispersed in a translucent resin is formed on the surface of a transparent film. Fig. 2 corresponds to a light diffusing sheet in which a light diffusing layer in which one kind of fine particle group is dispersed in a transparent resin is formed on the front and back surfaces of a transparent film. Fig. 3 corresponds to a light diffusing sheet in which a light diffusing / condensing layer is formed by dispersing two types of fine particle groups in a translucent resin on the surface of a transparent film. Figure 4 corresponds to a light diffusing sheet in which a light diffusing and condensing layer is formed on the front and back surfaces of a transparent film, in which two types of fine particles are dispersed in a translucent resin. FIG. 5 shows that a light diffusion layer in which one kind of fine particle group is dispersed in a transparent film is formed on the surface of the transparent film, and one kind of fine particle group in the light transparent resin is formed on the light diffusion layer. It corresponds to a light diffusion sheet with a light condensing layer embedded. Fig. 6 shows a condensing layer in which one type of fine particle group is embedded in a transparent film on the surface of the transparent film, and one type of fine particle in the transparent film on the back surface of the transparent film. This corresponds to a light diffusion sheet in which a light diffusion layer in which groups are dispersed is formed.

[0102] In addition, although not shown, a light diffusing condensing layer in which two or more kinds of fine particles are dispersed in a transparent resin is formed on the surface of the transparent film. A light diffusing sheet with a light diffusing layer in which one type of fine particle group is dispersed in a transparent resin on the back; one type of fine particle group is dispersed in a transparent film on the surface of a transparent film A light diffusion layer in which two or more kinds of fine particles are dispersed in a transparent resin on the back surface of the transparent film; a light diffusion sheet in which a light collecting layer is formed; etc. Can be considered.

[0103] The light diffusing sheet 10 shown in FIG. 1 has one type of translucent resin 11 on the surface of the transparent film 11. The light diffusion layer A in which the fine particle group 14 is dispersed is formed. The fine particle group 14 is substantially uniformly dispersed in the light diffusion layer A, and substantially all of the fine particle group is embedded in the translucent resin 11. Here, the absolute value of the refractive index difference between the translucent resin 11 and the fine particle group 14 is 0.05 or more. The translucent resin 11 is preferably a (meth) acrylic resin containing inorganic ultrafine particles or organic / inorganic composite ultrafine particles. The light incident on the back surface of the transparent film 11 passes through the transparent film 11 and enters the light diffusion layer A. In the light diffusion layer A, diffused light is emitted after being sufficiently diffused by the fine particle group 14 dispersed in the translucent resin 11. Since the fine particle group 14 is present substantially over the entire light diffusion layer A, more diffused light is emitted and luminance unevenness is reduced. The light diffusion sheet 10 shown in FIG. 1 may be used upside down.

A light diffusing sheet 20 shown in FIG. 2 has a light diffusing layer A in which one kind of fine particle group 22 is dispersed in a translucent resin 23 formed on the surface of a transparent film 21. Similarly, a light diffusion layer A in which one kind of fine particle group 22 is dispersed in a translucent resin 23 is formed on the back surface. The fine particle group 22 is substantially uniformly dispersed in the light diffusion layer A, and substantially all the fine particle group is embedded in the translucent resin 23. Here, the absolute value of the refractive index difference between the translucent resin 23 and the fine particle group 22 is 0.05 or more. The translucent resin 23 is preferably a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles. The light incident on the light diffusion layer A formed on the back surface of the transparent film 21 is sufficiently diffused by the fine particle group 22 dispersed in the translucent resin 23, and then passes through the transparent film 21 and passes through the transparent film 21. The light enters the light diffusion layer A formed on the surface of 21. In the light diffusion layer A, diffused light is emitted after being sufficiently diffused by the fine particle group 22 dispersed in the translucent resin 23. Since the particle group 22 is present substantially over the entire light diffusion layer A, more diffused light is emitted and luminance unevenness is reduced.

The light diffusing sheet 30 shown in FIG. 3 has a light diffusing / condensing layer B in which two kinds of fine particle groups 34 and 35 are dispersed in a transparent resin 33 on the surface of a transparent film 31. Yes. The fine particle groups 34 and 35 are substantially uniformly dispersed in the light diffusion / condensing layer B, and some of the fine particle groups partially protrude from the light diffusion / condensing layer B. Here, the absolute value of the refractive index difference between the translucent resin 33 and the fine particle group 34 is 0.05 or more. Translucent rosin 33 is preferred Or (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles. The light incident on the back surface of the transparent film 31 passes through the transparent film 31 and enters the light diffusion / condensing layer B. In the light diffusion / condensation layer B, after being sufficiently diffused by the fine particle group 34 dispersed in the translucent resin 33, the protruding part of the fine particle group 35 partially protruding from the translucent resin 33 The light is collected in the front direction by the (convex portion). Since the particle group 35 exists substantially throughout the light diffusing and condensing layer B, more light is collected in the front direction and luminance unevenness is reduced.

[0106] The light diffusion sheet 40 shown in FIG. 4 has a light diffusing condensing layer B in which two kinds of fine particle groups 44 and 45 are dispersed in a transparent resin 43 on the surface of a transparent film 41. Similarly, a light diffusing / condensing layer B in which two kinds of fine particle groups 44 and 45 are dispersed in a translucent resin 43 is formed on the back surface of the transparent film 41. The fine particle groups 44 and 45 are substantially uniformly dispersed in the light diffusing / condensing layer B, and some of the fine particle groups partially protrude from the light diffusing / condensing layer B. Here, the absolute value of the refractive index difference between the translucent resin 43 and the fine particle group 44 is 0.05 or more. The translucent resin 43 is preferably a (meth) acrylic resin containing inorganic ultrafine particles or organic inorganic composite ultrafine particles. Light diffused on the back surface of the transparent film 41 'Light incident on the condensing layer B is partly diffused by the fine particle group 44 dispersed in the translucent resin 43 and partly translucent. After being condensed by the protruding part (convex part) of the fine particle group 45 partially protruding from the synthetic resin 43, it passes through the transparent film 41, and then the light diffusion 'condensing formed on the surface of the transparent film 41 Incident to layer B. In the light diffusing condensing layer B, after being sufficiently diffused by the fine particle group 45 dispersed in the translucent resin 43, the protruding portion of the fine particle group 45 partially protruding from the translucent resin 43 ( The light is collected in the front direction by the convex portion. Since the particle group 45 is present substantially over the entire light diffusion / condensing layer B, more light is condensed in the front direction and luminance unevenness is reduced.

In the light diffusion sheet 50 shown in FIG. 5, a light diffusion layer C in which one kind of fine particle group 54 is dispersed in a translucent resin 53 is formed on the surface of a transparent film 51, and the light diffusion layer C On top of this, a condensing layer D in which five kinds of fine particle groups 56 are embedded in a translucent resin 55 is formed. Here, the absolute value of the refractive index difference between the translucent resin 53 and the fine particle group 54 is 0.05 or more. The surface roughness of the light collecting layer D is preferably an arithmetic average roughness of 0.5 / zm or more and 7 m or less. Fine particles The subgroups 54 are substantially uniformly dispersed in the light diffusion layer C, and the fine particle group 56 also partially projects the condensing layer D force. The light incident on the back surface of the transparent film 51 passes through the transparent film 51 and enters the light diffusion layer C. In the light diffusion layer C, it is sufficiently diffused by the fine particle group 54 dispersed in the translucent resin 53 and then enters the light condensing layer D. In the condensing layer D, light is condensed in the front direction by the protruding portion (convex portion) of the fine particle group 56 partially protruding from the translucent resin 55. Since the particle group 56 exists on substantially the entire surface of the condensing layer D, more light is condensed in the front direction and luminance unevenness is reduced.

A light diffusing sheet 60 shown in FIG. 6 has a light condensing layer D in which one type of fine particle group 66 is embedded in a transparent resin 65 on the surface of a transparent film 61. A light diffusion layer C in which one kind of fine particle group 64 is dispersed in a transparent resin 63 is formed on the back surface. Here, the absolute value of the refractive index difference between the translucent resin 63 and the fine particle group 64 is 0.05 or more. Further, the surface roughness of the light collecting layer D is preferably not less than 0 and not more than the arithmetic average roughness. The fine particle group 64 is substantially uniformly dispersed in the light diffusion layer C, and the fine particle group 66 also partially projects the condensing layer D force. The light incident on the light diffusion layer C formed on the back surface of the transparent film 61 is sufficiently diffused by the fine particle group 64 dispersed in the translucent resin 63, and then passes through the transparent film 61. The light enters the condensing layer D formed on the surface of 61. In the condensing layer D, light is condensed in the front direction by the protruding portion (convex portion) of the fine particle group 66 partially protruding from the translucent resin 65. Since the fine particle group 66 exists on substantially the entire surface of the condensing layer D, more light is condensed in the front direction and luminance unevenness is reduced.

[0109] <Method for producing light diffusion sheet>

Among the light diffusing sheets of the present invention, for example, a light diffusing sheet 10 shown in FIG. 1 is prepared by first mixing a composition obtained by kneading one kind of fine particle group 14 with a light transmitting resin 13 constituting a light diffusing layer A. After coating directly on the surface of the transparent film 11, the light-transmitting resin 13 is dried to form the light diffusion layer A.

[0110] The light diffusing sheet 20 shown in FIG. 2 is first coated directly on the surface of the transparent film 21 with a composition in which one kind of fine particle group 24 is kneaded with the translucent resin 23 constituting the light diffusing layer A. After that, the translucent resin 23 is dried to form a light diffusion layer A, and then the same composition as above It can be manufactured by directly coating an object on the back surface of the transparent film 21 and then drying the translucent resin 23 to form the light diffusion layer A. Of course, first, after forming the light diffusion layer A on the back surface of the transparent film 21, the light diffusion layer A may be formed on the surface of the transparent film 21.

[0111] A light diffusing sheet 30 shown in FIG. 3 is prepared by first mixing a composition obtained by kneading two kinds of fine particle groups 34 and 35 with a light transmissive resin 33 constituting a light diffusing 'condensing layer B. After coating directly on the surface, the light-transmitting resin 33 is dried to form a light diffusing and condensing layer B.

[0112] The light diffusing sheet shown in FIG. 4 is prepared by first mixing a composition obtained by kneading two kinds of fine particle groups 44 and 45 with the light transmissive resin 43 constituting the light diffusing 'condensing layer B. After coating directly onto the transparent film 41, the light-transmitting resin 43 is dried to form a light diffusion / diffusion layer B, and then the back surface of the transparent film 41 is directly coated with the same composition as above. It can be produced by drying the translucent resin 43 to form the light diffusion / condensing layer B. Of course, first, the light diffusion / condensing layer B may be formed on the back surface of the transparent film 41, and then the light diffusion / condensing layer B may be formed on the surface of the transparent film 41.

[0113] In the light diffusion sheet 50 shown in FIG. 5, first, the surface of the transparent film 51 is directly coated with a composition in which one kind of fine particle group 54 is kneaded with the translucent resin 53 constituting the light diffusion layer C. After that, the light-transmitting resin 53 is dried to form a light diffusion layer C, and then the light-transmitting resin 55 constituting the light-collecting layer D is kneaded with one kind of fine particle group 56. Can be manufactured by coating the light diffusing layer C directly and then drying the translucent resin 55 to form the light collecting layer D.

[0114] In the light diffusion sheet 60 shown in FIG. 6, first, the back surface of the transparent film 61 is directly coated with a composition in which one kind of fine particle group 64 is kneaded with the translucent resin 63 constituting the light diffusion layer C. After that, the light transmissive resin 63 is dried to form the light diffusion layer C, and then the light transmissive resin 65 constituting the light condensing layer D is kneaded with one kind of fine particle group 66. Can be produced by directly coating the surface of the transparent film 61 and then drying the light-transmitting resin 65 to form the light-collecting layer D. Of course, first, the light condensing layer D may be formed on the surface of the transparent film 61, and then the light diffusion layer C may be formed on the back surface of the transparent film 61. [0115] An organic solvent may be used when the fine particle group is kneaded with the translucent resin. The organic solvent is not particularly limited as long as it is appropriately selected in consideration of the solubility, workability, cost, etc. of each component. Specifically, for example, aromatic solvents such as toluene and xylene are used. Hydrocarbon solvents; Aliphatic hydrocarbon solvents such as hexane and heptane; Ester solvents such as ethyl acetate and butyl acetate; Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; Isopropyl alcohol and butyl alcohol Alcohol-based solvents such as; petroleum fractions having various boiling points mainly composed of aliphatic hydrocarbons; and the like. These organic solvents may be used alone or in combination of two or more.

[0116] The method of directly coating the composition obtained by kneading the fine particle group in the translucent resin is not particularly limited as long as a conventionally known coating technique is employed. The method for drying the translucent rosin is not particularly limited as long as a conventionally known drying method is adopted.

[0117] <Application of light diffusion sheet>

The light diffusion sheet of the present invention may be used in a conventionally known direct type or edge light type backlight unit as a light diffusion sheet of a direct type or edge light type backlight unit. It is preferably used for a type backlight unit. In addition, the light diffusion sheet of the present invention can be widely used for applications such as a screen for a projection display device, a plasma display device, an electoluminescence display device, and the like for expanding the viewing angle.

[0118] <Light Diffuser>

The light diffusing plate of the present invention has a light transmissive layer in which at least one surface of a transparent support is formed with a light diffusing layer in which at least one fine particle group is dispersed in a light transmissive resin, and constitutes the light diffusing layer. The absolute value of the refractive index difference between the resin and the group of at least one kind of fine particles is 0.05 or more, or at least one kind of fine particles in the translucent resin on one side of the transparent film. A light diffusing sheet in which a light diffusing layer in which groups are dispersed is bonded to at least one surface of a transparent support with an adhesive or a pressure-sensitive adhesive, and at least 1 It is characterized in that the absolute value of the difference in refractive index from the type of fine particle group is 0.05 or more. [0119] In the light diffusing plate of the present invention, at least one of the light diffusing layers contains two kinds of fine particle groups, and the surface roughness of the light diffusing layer is not less than 0. It is preferable. Such a light diffusing layer has a light condensing property in addition to a light diffusing property, and therefore is sometimes called a “light diffusing / condensing layer”.

[0120] Further, a light diffusing layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on one surface of the transparent support, and the translucent resin is formed on the light diffusing layer. It is preferable that a condensing layer in which at least one kind of fine particle group is embedded is formed, and that the surface roughness of the condensing layer is an arithmetic average roughness of 0.5 μm or more and 7 μm or less.

[0121] Alternatively, a light diffusion layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on one surface of the transparent support, and the translucent resin is formed on the opposite surface of the transparent support. It is preferable that a condensing layer in which at least one kind of fine particle group is embedded is formed, and that the surface roughness of the condensing layer is an arithmetic average roughness of 0.5 m or more and 7 m or less.

[0122] Alternatively, a light diffusing layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on one surface of the transparent support, and at least 1 of the translucent resin is formed on one surface of the transparent film. A condensing sheet having a condensing layer in which various kinds of fine particle groups are embedded is attached to the opposite surface of the transparent support with an adhesive or an adhesive, and the surface roughness of the condensing layer is arithmetically averaged. The roughness is preferably 0.5 μm or more and 7 μm or less.

[0123] Alternatively, a light diffusing layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one side of the transparent film, and at least 1 in the transparent resin is formed on the light diffusing layer. A light diffusing sheet on which a condensing layer in which various kinds of fine particle groups are embedded is formed is bonded to one side of the transparent support with an adhesive or an adhesive, and the surface roughness of the condensing layer is an arithmetic average roughness. It is preferably 0.5 m or more and 7 μm or less.

[0124] Alternatively, a light diffusing sheet in which a light diffusing layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one side of a transparent film is an adhesive on one side of the transparent support. Is bonded with an adhesive, and a condensing layer is formed on the opposite surface of the transparent support with at least one fine particle group embedded in translucent resin, and the surface roughness of the condensing layer is arithmetic The average roughness is preferably 0.5 μm or more and 7 μm or less.

[0125] Alternatively, on one side of the transparent film, at least one type of fine particle group is separated in the translucent resin. A light diffusing sheet having a light diffusing layer dispersed thereon is bonded to one side of the transparent support with an adhesive or a pressure-sensitive adhesive, and at least one kind of fine particle group composed of translucent resin on one side of the transparent film. A condensing sheet with a condensing layer embedded therein is attached to the opposite surface of the transparent support with an adhesive or a pressure-sensitive adhesive, and the surface roughness of the condensing layer is an arithmetic average roughness of 0. It is preferably 5 μm or more and 7 μm or less.

[0126] Further, it is preferable that the translucent resin is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles.

[0127] In the light diffusing plate of the present invention, the light diffusing layer and the fine particle group constituting the light diffusing layer and the light condensing layer, and the light diffusing layer in which at least one kind of fine particle group is dispersed in the light transmissive resin. The light condensing layer, transparent film, and the like in which at least one kind of fine particle group is embedded in a translucent resin are the same as in the case of the light diffusion sheet described above, and thus the description thereof is omitted here. In addition, when using the above description regarding the light diffusing sheet, “light diffusing sheet” shall be read as “light diffusing plate” as necessary.

In the light diffusing plate of the present invention, the resin used as the translucent resin constituting the light diffusing layer and the light collecting layer has an appropriate hardness and toughness. Excellent scratch resistance with few scratches on the plate and contact members, easy handling during production, storage, transportation, use, etc., and yield improvement.

[0129] <Transparent support>

In the light diffusing plate of the present invention, the transparent support may be made of, for example, a (meth) acrylic resin such as polymethyl methacrylate; a rataton containing a rataton ring structural unit derived from 2- (hydroxyalkyl) acrylate. Ring-containing resin; Styrene resin such as MS resin; Olefin resin such as polyethylene and polypropylene; Cyclic olefin resin such as norbornene resin; Salt vinyl resin; Salt resin -Ridene-based resin; Polyester-based resin such as polyethylene terephthalate and polyethylene naphthalate; Polycarbonate-based resin; Copolymers of these; and other inorganic materials such as glass . Of these materials, (meth) acrylic resin, rubber ring-containing resin, MS resin, cyclic olefin-based resin, polycarbonate-based resin, and glass are preferable.

[0130] Among transparent support materials, transparent thermoplastic resins include, for example, stabilizers and prevention of deterioration. You may mix | blend additives, such as an agent, a plasticizer, and a dispersing agent. The blending amount of these additives is not particularly limited as long as it is appropriately adjusted according to the type of the additive.

[0131] The transparent support may be formed of a single material or two or more materials, and may be formed of a single layer or a plurality of layers. May

[0132] The thickness of the transparent support is not particularly limited as long as the transparent support itself does not suffice and has a mechanical strength that does not cause the light diffusion sheet to squeeze. It is preferably 0.3 mm or more and 10 mm or less, more preferably 0.5 mm or more and 7 mm or less, and further preferably lmm or more and 5 mm or less. If the thickness of the transparent support is less than 0.3 mm, the mechanical strength of the light diffusing plate may decrease. Conversely, if the thickness of the transparent support exceeds 10 mm, the thickness of the knocklight unit may increase.

[0133] The transparent support preferably has a haze of 0% or more and 20% or less, more preferably 0% or more, 10% or less, more preferably 0% or more and 5% or less, and Z or all The light transmittance is preferably 70% or more and 100% or less, more preferably 80% or more and 100% or less. The haze and total light transmittance are values measured by a measurement method based on JIS K7105 using a turbidimeter (for example, NDH-1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0134] It should be noted that members such as a transparent support and a light diffusion layer that directly receive light of light source power may contain an ultraviolet absorber in order to prevent the influence of ultraviolet rays. It is also possible to provide an ultraviolet absorbing layer on the surface that receives light with a strong light source. Members that come into contact with the air layer, such as a transparent support, light diffusing layer, and condensing layer, are affected by dust in the air. In order to prevent this, an antistatic agent may be contained in these members, or an antistatic layer may be provided on the surface in contact with the air layer.

[0135] <Configuration example of light diffusing plate>

Here, the concrete structural example of the light diffusing plate of this invention is shown to FIGS. FIG. 7 corresponds to a light diffusing plate in which a light diffusing layer in which one kind of fine particle group is dispersed in a translucent resin is formed on the surface of the transparent support. In FIG. 8, a light diffusing layer in which two kinds of fine particle groups are dispersed in a translucent resin is formed on the surface of the transparent support and corresponds to a light diffusing plate. Fig. 9 shows a light diffusion layer in which a single particle group is dispersed in a transparent resin on the surface of a transparent support. It corresponds to a light diffusing plate formed on the light diffusing layer and having a condensing layer in which one kind of fine particle group is embedded in a light transmissive resin. FIG. 10 shows that a condensing layer in which one type of fine particle group is embedded in a transparent support is formed on the surface of the transparent support, and one type of translucent resin is provided on the back of the transparent support. It corresponds to a light diffusing plate on which a light diffusing layer in which fine particles are dispersed is formed. FIG. 11 shows a light diffusing sheet in which a light diffusing layer in which one type of fine particle group is dispersed in a translucent resin is formed on the surface of a transparent film, and an adhesive or an adhesive on the surface of the transparent support. It corresponds to the light diffusing plate bonded together. Fig. 12 shows that a light diffusing sheet in which a light diffusing layer in which two types of fine particles are dispersed in a transparent resin is formed on the surface of a transparent film is bonded to the surface of the transparent support with an adhesive or an adhesive. It corresponds to the light diffusion plate. Fig. 13 shows that a light diffusing layer in which one kind of fine particle group is dispersed in a transparent film is formed on the surface of the transparent film, and one kind of fine particle group is formed on the light diffusing layer on the light diffusing layer. The light diffusion sheet on which the buried light-collecting layer is formed corresponds to the light diffusion plate bonded to the surface of the transparent support with an adhesive or a pressure-sensitive adhesive. Fig. 14 shows that a condensing sheet in which a condensing layer in which one type of fine particle group is embedded in a transparent film is formed on the surface of a transparent film is bonded to the surface of the transparent support with an adhesive or an adhesive. A light diffusion sheet in which a light diffusion layer in which one kind of fine particle group is dispersed in a transparent resin is formed on the back surface of the transparent film is bonded to the back surface of the transparent support with an adhesive or an adhesive. It corresponds to the light diffusion plate.

In addition, although not shown, a light diffusing plate in which a light diffusing layer in which one kind of fine particle group is dispersed in a transparent resin is formed on both surfaces of the transparent support; on both surfaces of the transparent support, Light diffusing plate in which two or more kinds of fine particles are dispersed in translucent resin; light diffusing plate with condensing layer formed; one kind of fine particles in translucent resin on the surface of transparent film A light diffusing sheet in which a light diffusing layer in which a light diffusing layer is dispersed is bonded to both sides of a transparent support with an adhesive or a pressure sensitive adhesive; two types of translucent resin on the surface of a transparent film, or Light diffusion sheet in which three or more kinds of fine particles are dispersed 'Light diffusion sheet with light condensing layer formed on both sides of transparent support with adhesive or adhesive; surface of transparent support In addition, a light diffusion layer in which one type of fine particle group is dispersed in a transparent resin is formed, and the back of the transparent film is formed. Formed on the surface is a light diffusion layer in which one type of fine particle group is dispersed in translucent resin A light diffusing plate in which the light diffusing sheet is bonded to the back surface of the transparent support with an adhesive or a pressure sensitive adhesive; a light diffusing layer in which one kind of fine particle group is dispersed in a translucent resin on the surface of the transparent film A light diffusing sheet on which is formed is bonded to the surface of a transparent support with an adhesive or a pressure-sensitive adhesive, and light in which one kind of fine particle group is dispersed in a transparent resin on the back surface of the transparent support. A light diffusing plate with a diffusion layer formed on it; a light diffusing condensing layer in which two or more kinds of fine particles are dispersed in a transparent support is formed on the surface of a transparent support, and a transparent film A light diffusing sheet in which two or more kinds of fine particle groups are dispersed in a translucent resin is formed on the back surface of the transparent support with an adhesive or an adhesive on the back surface of the transparent support. Bonded light diffusing plate; 2 or 3 or more kinds of translucent resin on the surface of the transparent film A light diffusion sheet in which a child group is dispersed A light diffusion sheet on which a diffusion layer is formed is bonded to the surface of the transparent support with an adhesive or a pressure-sensitive adhesive, and the transparent support is coated on the back surface of the transparent support. Light diffusing plate in which two or more types of fine particles are dispersed; a light diffusing plate in which a diffusion layer is formed; light condensing with one type of fine particles embedded in a transparent support on the surface of a transparent support A light diffusion sheet in which a light diffusing layer in which one kind of fine particle group is dispersed in a transparent resin is formed on the back surface of the transparent film is formed on the back surface of the transparent support. Light diffusion plate bonded with an adhesive; a light-condensing sheet in which a light-condensing layer in which one type of fine particle group is embedded in a transparent film is formed on the surface of a transparent film is attached to the surface of the transparent support Or, it is bonded with an adhesive, and one kind of fine particle group is added to the transparent resin on the back of the transparent support. A light diffusing plate on which a dispersed light diffusing layer is formed may be considered.

In the light diffusing plate 70 shown in FIG. 7, a light diffusing layer A in which one type of fine particle group 74 is dispersed in a translucent resin 73 is formed on the surface of a transparent support 72. The fine particle group 74 is substantially uniformly dispersed in the light diffusion layer A, and substantially all of the fine particle group is embedded in the translucent resin 73. Here, the absolute value of the refractive index difference between the translucent resin 73 and the fine particle group 74 is 0.05 or more. The translucent resin 73 is preferably a (meth) acrylic resin containing inorganic ultrafine particles or organic inorganic composite ultrafine particles. Light incident from the back surface of the transparent support 72 is sufficiently diffused by the fine particle group 74 and then travels to a liquid crystal display panel (not shown). Note that the light diffusing plate 70 shown in FIG. 7 may be used upside down.

[0138] The light diffusing plate 80 shown in Fig. 8 has two kinds of fine particles on the surface of the transparent support 82 and the translucent resin 83. A light diffusing / condensing layer B in which the particle groups 84 and 85 are dispersed is formed. The fine particle groups 84 and 85 are substantially uniformly dispersed in the light diffusion / condensing layer B, and some of the fine particle groups partially protrude from the light diffusion / condensing layer B. Here, the absolute value of the difference in refractive index between the translucent resin 83 and the fine particle group 84 is 0.05 or more. The translucent resin 83 is preferably a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles. Further, the surface roughness of the light diffusing light condensing layer B is an arithmetic average roughness, preferably 0.

This is the following. The light that has also entered the back surface force of the transparent support 82 passes through the transparent support 82 and enters the light diffusion / condensing layer B. In the light diffusion / condensing layer B, the incident light is sufficiently diffused by the fine particle group 84, and then the frontal direction is caused by the protruding portion (convex portion) of the fine particle group 85 partially protruding from the translucent resin 83. The light is focused on the liquid crystal display panel (not shown).

[0139] In the light diffusing plate 90 shown in FIG. 9, a light diffusing layer C in which one kind of fine particle group 94 is dispersed in a transparent resin 93 is formed on the surface of a transparent support 92, and the light diffusing layer C is formed. On layer C, a condensing layer D in which one kind of fine particle group 96 is embedded in translucent resin 95 is formed. Here, the absolute value of the refractive index difference between the translucent resin 93 and the fine particle group 94 is 0.05 or more. Further, the surface roughness of the light collecting layer D is preferably an arithmetic average roughness of 0.5 / z m or more and 7 m or less. The light that has also entered the back surface force of the transparent support 92 passes through the transparent support 92 and enters the light diffusion layer C. In the light diffusion layer C, the incident light is sufficiently diffused by the fine particle group 94 and then enters the light condensing layer D. In the light condensing layer D, the light is condensed in the front direction by the protruding portion (convex portion) of the fine particle group partially protruding from the translucent resin 95 and heads toward the liquid crystal display panel (not shown).

[0140] In the light diffusing plate 100 shown in Fig. 10, a condensing layer D in which one kind of fine particle group 106 is embedded in a transparent resin 105 is formed on the surface of a transparent support 102, and the transparent support 102 is formed. On the back surface of the body 102, a light diffusion layer C in which one kind of fine particle group 104 is dispersed in a translucent resin 103 is formed. Here, the absolute value of the refractive index difference between the translucent resin 103 and the fine particle group 104 is 0.05 or more. Further, the surface roughness of the light collecting layer D is preferably an arithmetic average roughness of 0.5 / zm or more and m or less. The light incident on the light diffusion layer C formed on the back surface of the transparent support 102 is sufficiently diffused by the fine particle group 104, passes through the transparent support 102, and is formed on the surface of the transparent support 102. Incident on the condensing layer D. In the condensing layer D, the translucent resin 105 is partially The light is condensed in the front direction by the protruding portion (convex portion) of the protruding fine particle group, and is directed to a liquid crystal display panel (not shown).

[0141] The light diffusing plate 110 shown in FIG. 11 is a light diffusing sheet in which a light diffusing layer A in which one kind of fine particle group 114 is dispersed in a translucent resin 113 is formed on the surface of a transparent film 111. The transparent support 112 is bonded to the surface with an adhesive or a pressure sensitive adhesive 118. The fine particle group 114 is substantially uniformly dispersed in the light diffusion layer A, and substantially all of the fine particle group is embedded in the translucent resin 113. Here, the absolute value of the refractive index difference between the translucent resin 113 and the fine particle group 114 is 0.05 or more. The translucent resin 113 is preferably a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles. The light incident from the back surface of the transparent support 112 passes through the transparent support 112, the adhesive or pressure-sensitive adhesive 118, and the transparent film 111 and enters the light diffusion layer A. In the light diffusion layer A, the incident light is sufficiently diffused by the fine particle group 114 and then travels to a liquid crystal display panel (not shown).

[0142] In the light diffusing plate 120 shown in FIG. 12, a light diffusing condensing layer B in which two kinds of fine particle groups 124 and 125 are dispersed in a transparent resin 123 is formed on the surface of a transparent film 121. The light diffusion sheet is bonded to the surface of the transparent support 122 with an adhesive or an adhesive 128. The fine particle groups 124 and 125 are substantially uniformly dispersed in the light diffusion / condensing layer B, and some of the fine particle groups partially protrude from the light diffusion / condensing layer B. Here, the absolute value of the refractive index difference between the translucent resin 123 and the fine particle group 124 is 0.05 or more. The translucent resin 123 is preferably a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles. The light that has also entered the back surface force of the transparent support 122 passes through the transparent support 122, the adhesive or pressure-sensitive adhesive 128, and the transparent film 121, and enters the light diffusing layer B. In the light diffusion and condensing layer B, the incident light is sufficiently diffused by the fine particle group 124, and then the front surface is projected by the protruding portion (convex portion) of the fine particle group 125 partially protruding from the translucent resin 123. The light is condensed in the direction toward the liquid crystal display panel (not shown).

In the light diffusion plate 130 shown in FIG. 13, a light diffusion layer C in which one kind of fine particle group 134 is dispersed in a transparent resin 133 is formed on the surface of the transparent film 131, and the light diffusion layer A light diffusing sheet with a condensing layer D formed by embedding one type of fine particle group 136 in transparent resin 135 on C Is bonded to the surface of the transparent support 132 with an adhesive or an adhesive 138. Here, the absolute value of the difference in refractive index between the translucent resin 133 and the fine particle group 134 is 0.05 or more. Further, the surface roughness of the light collecting layer D is preferably not less than 0 and not more than the arithmetic average roughness. The light that has also entered the back surface force of the transparent support 132 passes through the transparent support 132, the adhesive or adhesive 138, and the transparent film 131, and enters the light diffusion layer C. In the light diffusion layer, the incident light is sufficiently diffused by the fine particle group 134 and then enters the light condensing layer D. In the light condensing layer D, the light is condensed in the front direction by the protruding portion (convex portion) of the fine particle group partially protruding from the translucent resin 135 and is directed to the liquid crystal display panel (not shown).

[0144] The light diffusing plate 140 shown in FIG. 14 has a condensing sheet in which a condensing layer D in which one kind of fine particle group 146 is embedded in a transparent resin 141 is formed on the surface of a transparent film 141. A light diffusing layer C in which one kind of fine particle group 144 is dispersed in the transparent resin 141 is formed on the back surface of the transparent film 141 by being bonded to the surface of the transparent support 14 2 with an adhesive or an adhesive 148. The light diffusion sheet thus adhered is bonded to the back surface of the transparent support 142 with an adhesive or an adhesive 148. Here, the absolute value of the refractive index difference between the translucent resin 143 and the fine particle group 144 is 0.05 or more. The surface roughness of the light collecting layer D is preferably an arithmetic average roughness of not less than 0 and not more than 7 m. Light incident on the light diffusion layer C of the light diffusion sheet bonded to the back surface of the transparent support 142 is sufficiently diffused by the fine particle group 143, and then the transparent film 141, the adhesive or pressure sensitive adhesive 148, the transparent support Passes through 142, adhesive or adhesive 148, transparent film 141, and enters the light collecting layer D. In the light condensing layer D, the light is condensed in the front direction by the protruding portion (convex portion) of the fine particle group partially protruding from the translucent resin 145 and is directed to the liquid crystal display panel (not shown).

[0145] <Production Method of Light Diffusing Plate>

Among the light diffusing plates of the present invention, for example, the light diffusing plate shown in FIG. 7 is prepared by first transparently translating a composition in which one kind of fine particle group 74 is kneaded with a light transmitting resin 73 constituting the light diffusing layer A. It can be manufactured by coating the surface of the support 72 directly and then drying the translucent resin 73 to form the light diffusion layer A. Alternatively, when the transparent support 72 is composed of a transparent thermoplastic resin, the transparent thermoplastic resin constituting the transparent support 72 and one kind of fine particle group 74 in the translucent resin 73 Coextruded with the kneaded composition to prepare a transparent support 72 It can be manufactured by forming the light diffusion layer A on the surface.

[0146] In the light diffusing plate shown in FIG. 8, first, a transparent support 82 is prepared by mixing a composition obtained by kneading two kinds of fine particle groups 84 and 85 with a translucent resin 83 constituting a light diffusing 'condensing layer B. After the direct coating on the surface, the light-transmitting resin 53 is dried to form a light diffusion / condensing layer B. Alternatively, when the transparent support 82 is composed of a transparent thermoplastic resin, the transparent thermoplastic resin constituting the transparent support 82 and the translucent resin 83 are divided into two types of fine particle groups 84 and 85. It is possible to manufacture by coextruding a composition obtained by kneading the above and forming the light diffusing and condensing layer B on the surface of the transparent support 82.

[0147] In the light diffusing plate 90 shown in FIG. 9, first, the surface of the transparent support 92 is directly coated with a composition in which the fine particle group 94 is kneaded with the translucent resin 93 constituting the light diffusing layer C. The light transmissive resin 93 is dried to form a light diffusing layer C, and then a composition obtained by kneading the fine particle group 96 with the light transmissive resin 95 constituting the light collecting layer D is placed on the light diffusing layer C. After the direct coating, the light-transmitting resin 95 is dried to form the light-collecting layer D. Alternatively, when the transparent support 92 is made of a transparent thermoplastic resin, the fine particle group 94 is first kneaded with the transparent thermoplastic resin constituting the transparent support 92 and the translucent resin 93. A composition in which the light diffusing layer C is formed on the surface of the transparent support 92 by co-extrusion with the prepared composition, and then the fine-particle group 96 is kneaded with the translucent resin 95 constituting the condensing layer D. Can be manufactured by coating the light diffusing layer C directly and then drying the light transmissive resin 95 to form the light collecting layer D.

[0148] The light diffusing plate 100 shown in FIG. 10 is obtained by first directly coating the back surface of the transparent support 102 with a composition in which the fine particle group 104 is kneaded with the translucent resin 103 constituting the light diffusing layer C. The light transmissive resin 103 is dried to form the light diffusion layer C, and then the composition obtained by kneading the light transmissive resin 105 constituting the light collecting layer D with the fine particle group 106 is used as the transparent support 102. After the direct coating on the surface, the light-transmitting resin 105 is dried to form the light condensing layer D. Of course, first, the light condensing layer D may be formed on the surface of the transparent support 102, and then the light diffusion layer C may be formed on the back surface of the transparent support 102. Alternatively, when the transparent support 102 is made of a transparent thermoplastic resin, first, the fine particle group 104 is kneaded with the transparent thermoplastic resin constituting the transparent support 102 and the translucent resin 103. Composition By coextruding the product, a light diffusing layer C is formed on the back surface of the transparent support 102, and then a composition obtained by kneading the fine particle group 106 with the translucent resin 105 constituting the condensing layer D is obtained. It can be manufactured by coating the surface of the transparent support 102 directly and then drying the translucent resin 105 to form the light collecting layer D.

[0149] The light diffusing plate shown in FIG. 11 is first coated directly on the surface of the transparent film 111 with a composition in which one kind of fine particle group 114 is kneaded with the translucent resin 113 constituting the light diffusing layer A. The light diffusing sheet A is dried to form a light diffusing layer A, whereby a light diffusing sheet is prepared. Then, the light diffusing sheet is applied to the surface of the transparent support 112. The transparent film 111 can be produced by bonding with an adhesive or pressure-sensitive adhesive 118 so that the transparent film 111 faces the transparent support 112.

[0150] The light diffusing plate shown in FIG. 12 is prepared by first mixing a composition obtained by kneading two kinds of fine particle groups 124 and 125 with the light transmissive resin 123 constituting the light diffusing 'condensing layer B. After the direct coating, the light-transmitting resin 123 is dried to form a light diffusing condensing layer B to prepare a light diffusing sheet, and then the light diffusing sheet is used as a transparent support. It can be produced by adhering the transparent film 121 of the light diffusing sheet to the transparent support 122 on the surface of 122 2 with an adhesive or an adhesive 128.

[0151] In the light diffusing plate 130 shown in FIG. 13, first, a composition obtained by kneading the fine particle group 134 in the translucent resin 133 constituting the light diffusing layer C was directly coated on the surface of the transparent film 131. Thereafter, the light transmissive resin 133 is dried to form a light diffusing layer C, and then a composition obtained by kneading the light transmissive resin 135 constituting the light collecting layer D with the fine particle group 136 is added to the light diffusing layer. After coating directly on C, the light transmissive resin 135 is dried to form a light condensing layer D, whereby a light diffusing sheet is prepared, and then the light diffusing sheet is used as a transparent support. It can be manufactured by adhering the transparent film 131 of the light diffusing sheet to the transparent support 132 on the surface of 132 with an adhesive or an adhesive 138.

[0152] In the light diffusing plate 140 shown in FIG. 14, first, a composition in which the fine particle group 144 was kneaded with the translucent resin 143 constituting the light diffusing layer C was directly coated on the back surface of the transparent film 141. Thereafter, the light-transmitting resin 143 is dried to form a light diffusion layer C, whereby a light diffusion sheet is prepared and fine particles are added to the light-transmitting resin 145 constituting the light-collecting layer D. Group 146 was kneaded After the composition is directly coated on the surface of the transparent film 141, the light-transmitting resin 145 is dried to form the light-collecting layer D, thereby preparing a light-condensing sheet. Is attached to the back surface of the transparent support 142 with an adhesive or an adhesive 148 so that the transparent film 141 of the light diffusion sheet faces the transparent support 142, and this condensing sheet is attached to the transparent support 142. The transparent film 141 of the light condensing sheet is bonded to the surface with an adhesive or a pressure sensitive adhesive 148 so that the transparent film 142 faces the transparent support 142. Of course, first, the light condensing sheet may be bonded to the surface of the transparent support 142, and then the light diffusion sheet may be bonded to the back surface of the transparent support 142.

[0153] An organic solvent may be used when the fine particle group is kneaded with the translucent resin. The organic solvent is not particularly limited as long as it is appropriately selected in consideration of the solubility, workability, cost, and the like of each component. Specifically, for example, aromatic carbon such as toluene and xylene is used. Hydrogen solvents; Aliphatic hydrocarbon solvents such as hexane and heptane; Ester solvents such as ethyl acetate and butyl acetate; Ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; Isopropyl alcohol and butyl alcohol Alcohol-based solvents; petroleum fractions having various boiling points mainly composed of aliphatic hydrocarbons; and the like. These organic solvents may be used alone or in combination of two or more.

[0154] The method of directly coating the composition obtained by kneading the fine particle group in the translucent resin is not particularly limited as long as a conventionally known coating technique is employed. The method for drying the translucent rosin is not particularly limited as long as a conventionally known drying method is adopted.

[0155] Examples of the adhesive used to bond the light diffusing sheet and the light collecting sheet include acryl-based adhesives, polyester-based adhesives, polyamide-based adhesives, polyurethane-based adhesives, and isocyanate-based adhesives. And epoxy adhesives. These adhesives may be used alone or in combination of two or more. Of these adhesives, polyurethane adhesives, isocyanate adhesives, and acrylic adhesives are preferable, and polyurethane adhesives are particularly preferable. Examples of the pressure-sensitive adhesive used for bonding the light diffusion sheet and the light collecting sheet include an acrylic pressure-sensitive adhesive and a silicone pressure-sensitive adhesive. These adhesives may be used alone or in combination of two or more. Of these adhesives, acrylic A system-based pressure-sensitive adhesive is particularly suitable.

[0156] <Application of light diffusion plate>

The light diffusing plate of the present invention may be used in a conventionally known direct type backlight unit as a light diffusing plate of a direct type backlight unit, but is used in the direct type backlight unit of the present invention described below. Is preferred.

[0157] 《Backlight unit》

The backlight unit of the present invention has a light source, a reflection sheet, a transparent support, and the light diffusion sheet of the present invention described above, or a light source and a reflection sheet. The light diffusing sheet of the present invention described above is included, or the light diffusing sheet of the present invention described above is characterized by including a light source, a reflective sheet, and the light diffusing plate of the present invention described above. . As described above, the light diffusion sheet and the light diffusion plate of the present invention exhibit high light diffusibility by the light diffusion layer and high light condensing property by the light condensing layer, or high light diffusibility by the light diffusing layer. Therefore, the backlight unit of the present invention using such a light diffusion sheet or light diffusion plate is a light diffusion plate or light diffusion sheet for diffusing light, a prism sheet or light diffusion for condensing light. A backlight unit can be configured without using a sheet. That is, according to the present invention, when the light diffusibility and the light condensing property are excellent and the high total light transmittance and the luminance are obtained, the number of members of the satellite unit can be reduced while maintaining the basic optical characteristics. Can do.

[0158] <Light source and reflection sheet>

In the backlight unit of the present invention, the light source is not particularly limited as long as it is appropriately selected from various light sources used in conventionally known backlight units. Examples include fluorescent lamps (CCFL), external electrode fluorescent lamps (EEFL), flat fluorescent lamps (FFL), and light emitting diodes (LEDs). Further, the reflection sheet is not particularly limited as long as it is appropriately selected from various reflection sheets used in conventionally known backlight units. Synthetic resin sheet in which white pigment is dispersed, synthetic resin sheet in which bubbles for scattering light are dispersed, synthetic resin sheet in which the surface is formed in a mat shape, metal or alloy such as silver or aluminum is deposited on the surface Synthetic resin sheets and the like. [0159] <Transparent support>

In the backlight unit of the present invention, the material, thickness, configuration, characteristics and the like of the transparent support are the same as those described when the light diffusing plate of the present invention is described, and thus the description thereof is omitted here.

[0160] However, the transparent support used for supporting the light diffusing sheet of the present invention, not the transparent support used for the light diffusing plate of the present invention, has a pattern shape on the surface facing the light diffusing sheet. May be. The pattern shape is prismatic (specifically, a shape in which prism lens portions are arranged substantially in parallel), pyramid shape (specifically, a triangular pyramid or quadrangular pyramidal convex or concave portion is regular. Shape), hemisphere (specifically, a shape in which hemispherical convex or concave portions are regularly arranged) and various embossed patterns (for example, prism lenses) Shapes with irregularly arranged parts, shapes with triangular or quadrangular pyramidal projections or recesses irregularly, shapes with irregularly arranged hemispherical projections or recesses, and other arbitrary shapes Irregular shapes such as irregularly arranged convex or concave portions). These pattern shapes may be used alone or in combination of two or more. The pattern shape may be provided on the entire surface of the transparent support, or may be provided on a part of the surface of the transparent support (that is, there may be a portion where the pattern shape is not provided). If a regular shape is provided on the surface of the transparent support, the light guided to the light diffusion sheet can be controlled, so that the light from the light source can be diffused more efficiently. Light diffusion can be easily simulated with a light beam simulator. Further, if an irregular shape is provided on the surface of the transparent support, light from the light source can be diffused to some extent, so that the light diffusion effect can be further enhanced. As a method of providing a pattern shape on the surface of the transparent support, when the transparent support is made of thermoplastic resin, for example, when the transparent support is extruded, an embossing roll having a pattern shape is used. A method of embossing using a gravure roll; A method of applying a resin composition with a gravure roll having a pattern shape and drying or curing; After applying a photocurable resin, a laser light interference method is used for exposure. If the transparent support is composed of an inorganic material, the transparent support can be formed by laser processing, wet or dry etching, etc. Body table Examples thereof include a method of forming a pattern shape on the surface. These methods may be used alone or in combination of two or more. If the pattern shape is a regular shape, the pitch of the pattern shape is ί, preferably ί or more lm to 1,000 / zm, more preferably ί to 5 m or more, 800 m or less, more preferably 10 / zm or more, 500 / zm or less. If the pitch force of the pattern shape is less than m, or if it exceeds 1,000 m, the light from the light source may not be effectively diffused.

[0161] Of course, the transparent support used for supporting the light diffusion sheet of the present invention also contains an ultraviolet absorber or prevents light from the light source power in order to prevent the influence of ultraviolet rays. In order to prevent the influence of dust in the air, an antistatic agent is added or an antistatic layer is provided on the surface in contact with the air layer. You may keep it.

[0162] <Light diffusion sheet and light diffusion plate>

In the backlight unit of the present invention, the light diffusion sheet of the present invention described above (for example, the light diffusion sheet shown in FIGS. 1 to 6) is used as the light diffusion sheet. As the light diffusion plate, the light diffusion plate of the present invention described above (for example, the light diffusion plate shown in FIGS. 7 to 14) is used. In the knocklight of the present invention, either the light diffusing sheet of the present invention or the light diffusing plate of the present invention may be used alone, or both may be used together. A prism sheet and a brightness enhancement film (for example, DB EF manufactured by 3M) may be used in combination.

[0163] Configuration example of the backlight unit>

Here, specific configuration examples of the backlight unit of the present invention are shown in FIGS. 15 and 16 correspond to a backlight unit having a light source, a reflection sheet, a transparent support, and the light diffusion sheet of the present invention described above. FIG. 17 corresponds to a backlight unit having a light source, a reflection sheet, and the light diffusion sheet of the present invention described above. Further, FIG. 18 corresponds to a backlight unit having a light source, a reflection sheet, and the light diffusion plate of the present invention described above.

A backlight unit 150 shown in FIG. 15 includes a light source 151, a reflection sheet 152, a transparent support 153, and a light diffusion sheet 154. Here, as the light diffusion sheet 154, FIGS. The light diffusion sheet shown in FIG. A part of the light emitted from the light source 151 is directed to the transparent support 153, a part is reflected by the reflection sheet 152, and the force is also directed to the transparent support 153. The light incident on the transparent support 153 passes through the transparent support 153 and enters the light diffusion sheet 154. The light incident on the light diffusion sheet 154 is sufficiently diffused by the light diffusion layer A as shown in the light diffusion sheets 10 and 20 shown in FIGS. 1 and 2, or the light diffusion shown in FIGS. 3 and 4, respectively. As in sheets 30 and 40, the light is diffused sufficiently by the light condensing layer B and condensed in the front direction, or as in the light diffusion sheets 50 and 60 shown in FIGS. 5 and 6, respectively. After being sufficiently diffused by the diffusion layer C, the light is condensed in the front direction by the light condensing layer D and is directed to a liquid crystal display panel (not shown).

The backlight unit 160 shown in FIG. 16 includes a light source 161, a reflection sheet 162, a transparent support 163, and a light diffusion sheet 164. Here, as the light diffusion sheet 164, the light diffusion sheet shown in FIGS. A part of the light emitted from the light source 161 is directed to the transparent support 163, and part of the light is reflected by the reflection sheet 162, and the force is also directed to the transparent support 163. The light incident on the transparent support 163 passes through the transparent support 163 and forms a pattern formed on the surface of the transparent support 163 (FIG. 16 shows a hemispherical pattern as a specific example. However, it is not limited to this shape) and is then incident on the light diffusion sheet 164. The light incident on the light diffusing sheet 164 is sufficiently diffused by the light diffusing layer A, as shown in FIGS. 1 and 2, respectively, or in FIGS. 3 and 4, respectively. As shown in the light diffusion sheets 30 and 40 shown in FIG. 5, it is sufficiently diffused by the light diffusion 'condensing layer B and condensed in the front direction, or the light diffusion sheets 50 and 60 shown in FIGS. 5 and 6 respectively. As described above, after being sufficiently diffused by the light diffusion layer C, the light is condensed in the front direction by the light condensing layer D, and is directed to a liquid crystal display panel (not shown).

A backlight unit 170 shown in FIG. 17 includes a light source 171, a reflection sheet 172, and a light diffusion sheet 174. Here, as the light diffusion sheet 174, the light diffusion sheet force S shown in FIGS. The light diffusion sheet 174 is supported by a support member (not shown) without using a transparent support. A part of the light emitted from the light source 171 is directed to the light diffusion sheet 174, a part is reflected by the reflection sheet 172, and the force is also directed to the light diffusion sheet 174. Light incident on the light diffusing sheet 174 is reflected by the light diffusing sheets 10 and 20 shown in FIGS. 1 and 2, respectively. Thus, the force sufficiently diffused by the light diffusing layer A, or the light diffusing 'light condensing layer B as shown in FIGS. Condensed force Alternatively, after being sufficiently diffused by the light diffusing layer C, as shown in FIGS. 5 and 6, respectively, after being sufficiently diffused by the light diffusing layer C, the light is condensed in the front direction by the liquid crystal. Head to the display panel (not shown).

The backlight unit 180 shown in FIG. 18 includes a light source 181, a reflection sheet 182, and a light diffusing plate 183. Here, as the light diffusion plate 183, the light diffusion plate shown in FIGS. A part of the light emitted from the light source 181 is directed to the light diffusing plate 183, and part of the light is reflected by the reflection sheet 182 and travels toward the force light diffusing plate 183. The light incident on the light diffusion plate 183 is sufficiently diffused by the light diffusion layer A as shown in the light diffusion plates 70 and 110 shown in FIGS. 7 and 11, respectively, or the light shown in FIGS. 8 and 12, respectively. Like the diffuser plates 80 and 120, it is sufficiently diffused by the light diffusing / condensing layer B and condensed in the front direction, or the light diffusing plate 90, shown in FIGS. 9, 10, 13 and 14, respectively. After being sufficiently diffused by the light diffusion layer, such as 100, 130, and 140, the light is condensed in the front direction by the light condensing layer D and is directed to a liquid crystal display panel (not shown).

[0168] The backlight units shown in Figs. 15 to 18 use either the light diffusion sheet or the light diffusion plate of the present invention. As described above, the light diffusion sheet and the light diffusion sheet of the present invention and Both of the light diffusing plates may be used together, or a conventionally known light diffusing sheet, prism sheet, and brightness enhancement film (for example, DBEF manufactured by 3M) may be used in combination.

[0169] <Manufacturing method of backlight unit>

The backlight unit of the present invention is at least a light source, a reflection sheet, a transparent support, a light, except that it is not always necessary to use a light diffusing plate or a prism sheet used in a conventionally known backlight unit. It can be assembled from a diffusion sheet, from a light source, a reflection sheet, and a light diffusion sheet, or from a light source, a reflection sheet, and a light diffusion plate in the same manner as a conventionally known knock light unit. Therefore, the method for assembling the backlight unit of the present invention is not particularly limited. In the case of the backlight unit of the present invention, the light diffusing sheet and the light diffusing plate alone have high light diffusing properties and high light collecting properties. Can be used together with Since there is no need to use a sheet or, in some cases, a transparent support, it is possible to reduce at least one to three members of the knock light unit, which in turn reduces the cost of assembly. be able to.

[0170] Uses of Backlight Unit>

The backlight unit of the present invention can be suitably used as a light source for image display of a transmissive liquid crystal display device, particularly for applications such as liquid crystal televisions and liquid crystal displays.

[0171] <Liquid crystal display device>

The liquid crystal display device of the present invention includes the backlight unit of the present invention described above. Since the backlight unit of the present invention is preferably a direct type backlight unit, the liquid crystal display device of the present invention preferably has a relatively large screen size. Therefore, the liquid crystal display device of the present invention can be suitably used particularly for applications such as liquid crystal televisions and liquid crystal displays having a relatively large screen size.

[0172] The liquid crystal display device of the present invention has the same components as those of conventionally known liquid crystal display devices, except that the knocklight unit is the knocklight unit of the present invention. Therefore, the liquid crystal display device of the present invention can be manufactured in the same manner as a conventionally known liquid crystal display device except that the backlight unit of the present invention is used as the knock light unit.

[0173] Since the liquid crystal display device of the present invention uses the backlight unit of the present invention, the liquid crystal display device can provide high brightness, small display unevenness, uniform brightness and display.

Example

[0174] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as well as the present invention. It is also possible to carry out with addition, and they are all included in the technical scope of the present invention.

(1) In the following Examples 1 1 to 14 and Comparative Examples 1 1 to 16, in order to obtain a light diffusing sheet having high performance, the light transmissive resin and the fine particle group constituting the light diffusing layer It is demonstrated that the condition that the absolute value of the difference in refractive index between and is 0.05 or more is necessary.

[0176] First, a method for measuring physical properties of elements constituting a light diffusing sheet and a light diffusing sheet I will explain how to evaluate the performance of the!

[0177] <Refractive index of translucent resin>

The refractive index of the translucent resin constituting the light diffusing layer is the isocyanate group (Desmodur N3200, manufactured by Sumika Bayer Urethane Co., Ltd.), a hydroxyl group (OH group) of the translucent resin and a polyfunctional isocyanate compound (manufactured by Sumika Bayer Urethane Co., Ltd.) After adding the polyfunctional isocyanate compound to the translucent resin so that the NCO group) becomes OH group ZNCO group = 1 (equivalent ratio), a 40 m thick film is used using a bar coater The refractive index of this film was measured with a multiwavelength Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.). The measurement wavelength was 589 nm and the measurement temperature was 25 ° C.

[0178] <Refractive index of fine particle group>

The refractive index of the fine particle group dispersed in the translucent resin constituting the light diffusing layer has several strengths of a standard refractory liquid (standard series, manufactured by Moritex Corp .; refractive index range n ²⁵ = 1.

D

300 ~ 2.11), place a group of fine particles on a slide glass, add a standard refractive liquid with the expected refractive index, sandwich it with a cover glass, and then at 25 ° C a transmission optical microscope (digital Microscope VHX-200, manufactured by Keyence Corporation; the light source lamp is a 12V, 100W halogen lamp (color temperature 3, 100K (at maximum light intensity)). The refractive index of the standard refractive liquid used when the interface was most difficult to see was taken as the refractive index of the fine particle group. However, if there are two types of standard refractive liquids used when the interface between the fine particle group and the standard refractive liquid is most difficult to see, the refractive index of the fine particle group is the intermediate value of these refractive indices. In addition, when the refractive index of the fine particle group is outside the refractive index range of Cargill's standard refractive liquid, the refractive index of the material is taken as the refractive index of the fine particle group.

[0179] <Surface roughness of condensing layer>

The surface roughness of the condensing layer can be obtained by measuring the arithmetic average roughness at 5 or more points randomly selected for each sample using a surface roughness meter (Dektak3030, manufactured by Nippon Vacuum Technology Co., Ltd.). This is the average of the measured values.

[0180] <Concentration layer thickness>

The thickness of the light condensing layer is determined for each sample by solidifying the sample of the light diffusion sheet or light diffusion plate with an epoxy-based resin, cutting with a microtome, and observing the obtained cross section with an electron microscope. It is the average value of the measured values obtained by measuring the layer thickness of the light collecting layer at 5 points or more. [0181] <Average particle size of fine particle group>

The average particle diameter of the fine particle group is a volume average particle diameter measured using a particle size distribution measuring device (for example, Multisizer II type, manufactured by Coulter Co., Ltd.).

[0182] Total light transmittance and haze>

The total light transmittance and haze of the sample were measured using a color difference meter (∑90, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0183] <Front brightness>

The front luminance of the sample was measured by the following method using a cold cathode tube (luminance on the light source: about 10,000 cd, m ² ) as a light source.

[0184] Measuring method:

In Examples 1 1 to 14 and Comparative Examples 1 1 to 14, a 2 mm thick polycarbonate transparent support was placed 5 mm away from the surface of the cold cathode tube, and a sample was placed thereon. A luminance meter (BM-7, manufactured by Topcon Corporation) was fixed at a position 50 cm away from the sample cover, and the luminance on the light source was measured.

[0185] In Comparative Examples 15 and 16, the light diffusing plate having a thickness of 2 mm, 5 mm away from the surface of the cold-cathode tube (used for the AQUOS LC-37AD5 LCD TV manufactured by Sharp Corporation) A scattering plate) was installed, and a sample was placed thereon. Luminance meter (B

M-7, manufactured by Topcon Corporation) was fixed, and the luminance on the light source was measured.

[0186] <Light source shape>

When measuring the front luminance, the shape of the light source was visually observed and evaluated according to the following criteria.

◯: The power source shape could not be confirmed;

Δ: The light source shape is blurred;

X: The light source shape was clearly confirmed.

[0187] << Example 1-1 >>

A polyethylene terephthalate film (Cosmo Shine A-4300, manufactured by Toyobo Co., Ltd .; thickness 100 m) was used as a transparent film.

[0188] First, as a translucent resin, a special acrylic resin containing a repeating unit derived from cyclohexylmethacrylate (Udouble S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49) 100 Part by mass, fine particle group, spherical fine particles of benzoguanamine 'formaldehyde condensate (Epester M05, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.66, average particle size 5.2 / ζ πι) 30 parts by mass, polyfunctional isocyanate Compound (Desmodur Ν3200, manufactured by Sumika Bayer Urethane Co., Ltd.) 10 parts by weight and 40 parts by weight of toluene are thoroughly stirred and mixed, and then applied onto the surface of the transparent film using a bar coater and dried. A light diffusing layer having a thickness of 19. was formed.

[0189] Next, as a translucent resin, a special acrylic resin containing a repeating unit derived from cyclohexyl methacrylate (Udouble S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49) 10 0 Particulate mass, fine particle group, polymethyl methacrylate cross-linked spherical microparticles (Eposta MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 13.5 / zm) 70 parts by mass, multifunctional Isocyanate compound (Desmodur N3200, manufactured by Sumika Bayer Urethane Co., Ltd.) 10 parts by mass and 80 parts by mass of toluene were sufficiently stirred and mixed, and then on the light diffusion layer formed above using a bar coater. It was applied and dried to form a light collecting layer with a thickness of 19.5 m.

[0190] By force, a light diffusing layer in which fine particles are dispersed in a translucent resin is formed on the surface of the transparent film, and the fine particles are embedded in the translucent resin on the light diffusing layer. A light diffusing sheet on which a condensing layer was formed was obtained. In the obtained light diffusing sheet, the absolute value of the refractive index difference between the translucent resin and the fine particle group constituting the light diffusing layer is 0.17, and the surface roughness of the light collecting layer is 2.2. m. The ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.4. The total light transmittance and haze of the obtained light diffusion sheet were 75% and 93%, respectively. In addition, the front luminance was 6755cdZm ² and the shape of the light source could not be confirmed. These results are shown in Table 1.

[0191] Further, a drawing-substituting photograph in which the surface of the light condensing layer of the light diffusion sheet obtained in this example was observed with a digital microscope (VHX-200, manufactured by Keyence Corporation; magnification 450 times) Shown in 9.

[0192] <Example 1-2>

A light diffusion layer having a thickness of 16. was formed on the back surface of the transparent film using the same material as in Example 11. Then, a light condensing layer having a thickness of 21.7 m was formed on the surface of the transparent film. . [0193] By force, a condensing layer is formed on the surface of the transparent film, in which fine particles are embedded in translucent resin, and the fine particles are dispersed in translucent resin on the back of the transparent film. A light diffusing sheet having the light diffusing layer formed thereon was obtained. In the obtained light diffusing sheet, the absolute value of the refractive index difference between the translucent resin constituting the light diffusing layer and the fine particle group is 0.17, and the surface roughness of the light collecting layer is 2.O. / zm. Further, the ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.6. The total light transmittance and haze of the obtained light diffusion sheet were 72% and 93%, respectively. Further, the front luminance was 6766 cdZm ² , and the shape of the light source could not be confirmed. These results are shown in Table 1.

[0194] <Example 1-3>

In Example 1-1, a cyclohexane compounded with organocolloidal silica was used as the translucent resin instead of special acrylic resin (Udable S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49). A polyfunctional isocyanate compound (Desmodur N3200, Residential module) using a special acrylic resin containing a repeating unit derived from hexylmethacrylate (Udouble C-3600, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51) Except for changing the blending amount of Kabayashi Urethane Co., Ltd. from 10 parts by weight to 16 parts by weight, light diffusion with a thickness of 18.1 m was applied to the surface of the transparent film in the same manner as in Example 1-1. After forming the layer, a light collecting layer having a thickness of 18. was formed on the light diffusion layer.

[0195] By force, a light diffusing layer in which fine particles are dispersed in a translucent resin is formed on the surface of the transparent film, and the fine particles are embedded in the translucent resin on the light diffusing layer. A light diffusing sheet on which a condensing layer was formed was obtained. In the obtained light diffusing sheet, the absolute value of the refractive index difference between the translucent resin and the fine particle group constituting the light diffusing layer is 0.15, and the surface roughness of the light collecting layer is 1.9. m. The ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.4. The total light transmittance and haze of the obtained light diffusion sheet were 84% and 92%, respectively. Further, the front luminance was 6714CdZm ^2, light source shape can be confirmed that ChikaraTsuta. These results are shown in Table 1.

[0196] << Example 1-4 >>

In Example 1-2, as a translucent resin, a special acrylic resin (Udouble S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49) was used instead of a special compound containing organocolloidal silica. In the same manner as in Example 12 except that acrylic resin (Udable C-3600, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51) was used, a transparent film with a thickness of 18. After the diffusion layer was formed, a light collecting layer having a thickness of 24.7 m was formed on the surface of the transparent film.

[0197] By force, a condensing layer is formed on the surface of the transparent film, in which fine particles are embedded in translucent resin, and the fine particles are dispersed in translucent resin on the back of the transparent film. A light diffusing sheet having the light diffusing layer formed thereon was obtained. In the obtained light diffusion sheet, the absolute value of the refractive index difference between the translucent resin and the fine particle group constituting the light diffusion layer is 0.15, and the surface roughness of the light collecting layer is 2.2. m. Further, the ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.8. The total light transmittance and haze of the obtained light diffusion sheet were 76% and 93%, respectively. The front luminance was 6600 cdZm ² , and the shape of the light source could not be confirmed. These results are shown in Table 1.

[0198] <Comparative Example 1 1>

[0199] First, as a translucent resin, a special acrylic resin (Udouble S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49), 100 parts by mass, as a fine particle group, a polymethyl methacrylate cross-linked product Spherical fine particles (Poster MA1004, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 4.3 m) 30 parts by mass, polyfunctional isocyanate compound (Desmodur N3200, Sumika Bayer Urethane Co., Ltd. 10 parts by mass and 40 parts by mass of toluene were sufficiently stirred and mixed, and then applied to the surface of the transparent film using a bar coater and dried to form a light diffusion layer having a thickness of 14.

[0200] Next, as a translucent resin, special acrylic resin (Udouble S-2840, manufactured by Nippon Catalysts Co., Ltd .; refractive index 1.49), 100 parts by mass, as a fine particle group, polymethyl methacrylate Spherical fine particles of epoxy cross-linked product (Poster MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 13.5 m) )) After mixing 10 parts by mass and 80 parts by mass of toluene sufficiently with a bar coater, it was applied onto the light diffusion layer formed above, dried, and dried to a thickness of 24.8 μm. A light collecting layer was formed. [0201] On the surface of the transparent film, a light diffusing layer in which fine particles are dispersed is formed on the surface of the transparent film, and the fine particles are embedded in the light transmissive resin on the light diffusing layer. A light diffusing sheet on which a condensing layer was formed was obtained. In the obtained light diffusing sheet, the absolute value of the refractive index difference between the translucent resin and the fine particle group constituting the light diffusing layer is 0.02, and the surface roughness of the light collecting layer is 2.1. μm. Further, the ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.8. The total light transmittance and haze of the obtained light diffusion sheet were 91% and 64%, respectively. The front luminance was 8724cdZm ² and the light source shape was clearly confirmed. These results are shown in Table 1.

[0202] << Comparative Example 1 2 >>

A light diffusion layer having a thickness of 18. was formed on the back surface of the transparent film using the same material as in Comparative Example 11 and then a light condensing layer having a thickness of 23.2 m was formed on the surface of the transparent film. .

[0203] A light condensing layer in which fine particles are embedded in translucent resin is formed on the surface of the transparent film, and the fine particles are dispersed in the transparent film on the back surface of the transparent film. A light diffusing sheet having the light diffusing layer formed thereon was obtained. In the obtained light diffusion sheet, the absolute value of the refractive index difference between the translucent resin and the fine particle group constituting the light diffusion layer is 0.02, and the surface roughness of the light collecting layer is 2.1. μm. Further, the ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.7. The total light transmittance and haze of the obtained light diffusion sheet were 79% and 89%, respectively. The front luminance was 8527 cdZm ² and the light source shape was blurred. These results are shown in Table 1.

[0204] << Comparative Example 1 3 >>

[0205] First, as a translucent resin, a special acrylic resin (Udouble S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49) 100 parts by mass, as a fine particle group, silica acrylic composite Spherical fine particles (Soliostar YS, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 4.2 ^ πι) 30 parts by mass, polyfunctional isocyanate compound (Desmodur Ν3200, Sumika Bayer Ureta) 10 parts by mass and 40 parts by mass of toluene after sufficiently stirring and mixing, using a bar coater, applied to the surface of the transparent film and dried to obtain a light diffusion layer having a thickness of 16. Formed.

[0206] Next, as a translucent resin, a special acrylic resin (Udouble S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49) 100 parts by mass, as a fine particle group, polymethyl methacrylate Spherical fine particles of epoxy cross-linked product (Poster MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 13.5 m) 70 parts by mass, polyfunctional isocyanate compound (Desmodur N3200, Sumika Neue Urethane ( 10 parts by mass and 80 parts by mass of toluene were sufficiently stirred and mixed, and then applied onto the light diffusion layer formed above using a bar coater and dried to a thickness of 18.9 μm The light condensing layer was formed.

[0207] On the surface of the transparent film, a light diffusing layer in which fine particles are dispersed in a transparent resin is formed, and the fine particles are embedded in the transparent resin on the light diffusing layer. A light diffusing sheet on which a condensing layer was formed was obtained. In the obtained light diffusing sheet, the absolute value of the refractive index difference between the translucent resin and the fine particle group constituting the light diffusing layer is 0.02, and the surface roughness of the light collecting layer is 2.1. μm. The ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.4. The total light transmittance and haze of the obtained light diffusion sheet were 93% and 73%, respectively. The front luminance was 8714cdZm ² and the light source shape was clearly confirmed. These results are shown in Table 1.

[0208] Comparative Example 1 4

A light diffusing layer having a thickness of 15. was formed on the back surface of the transparent film using the same material as in Comparative Example 13 and then a light condensing layer having a thickness of 23.1 m was formed on the surface of the transparent film. .

[0209] A light condensing layer in which fine particles are embedded in a translucent resin is formed on the surface of the transparent film, and the fine particles are added to the transparent film on the back surface of the transparent film. A light diffusing sheet on which a dispersed light diffusing layer was formed was obtained. In the obtained light diffusion sheet, the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and the fine particle group is 0.02, and the surface roughness of the light collecting layer is 2.O. / zm. Further, the ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.7. The total light transmittance and haze of the obtained light diffusion sheet were 78% and 79%, respectively. Further, the front luminance was 8662 cdZm ² and the light source shape was blurred. These results are shown in Table 1.

[0210] Comparative Example 1 5 When the front luminance was measured and the shape of the light source was measured using a light diffusing plate used for the AQUOS LC-37AD5 LCD TV manufactured by Sharp Corporation, the front luminance was 536 5cdZm ² and the shape of the light source I couldn't confirm it.

[0211] Comparative Example 1 6

[0212] As a translucent resin, special acrylic resin (Udouble S-2840, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.49), 100 parts by mass, as a fine particle group, a polymethyl methacrylate-based crosslinked product Spherical fine particles (Poster MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 13.5 μm) 70 parts by mass, polyfunctional isocyanate compound (Desmodur N3200, manufactured by Sumika Bayer Urethane Co., Ltd.) 10 parts by mass and 80 parts by mass of toluene were sufficiently stirred and mixed, and then applied onto the surface of the transparent film using a bar coater and dried to form a light collecting layer having a thickness of 24.3 m.

[0213] As a result, a light diffusing sheet was obtained in which only the light-collecting layer in which fine particles were embedded in translucent resin was formed on the surface of the transparent film. In the obtained light diffusion sheet, the surface roughness of the light collecting layer was 2.1 μm, and the ratio of the layer thickness to the average particle diameter of the fine particle group in the light collecting layer was 1.8. The total light transmittance and haze of the obtained light diffusion sheet were 81% and 89%, respectively. In addition, the front luminance was 5959cdZm ² and the light source shape was too strong to confirm. The front luminance was measured by using the light diffusing plate used in Comparative Example 15 in combination with the light diffusing sheet obtained in this Comparative Example.

[0214] [Table 1]

[0215] As is apparent from Table 1, Examples 1 1 to 1 satisfying the condition that the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and the fine particle group is 0.05 or more. The light diffusion sheet of 14 shows sufficient total light transmittance, high haze, and sufficient front brightness, so it has both sufficient light diffusibility and light collecting properties as a light diffusion sheet. Since the shape of the light source can be completely erased, it can be seen that it has the function of making the line light source a surface light source.

[0216] On the other hand, the light of Comparative Examples 1 1 to 14 that does not satisfy the condition that the absolute value of the refractive index difference between the translucent resin and the fine particle group constituting the light diffusion layer is 0.05 or more. The diffuser sheet exhibits sufficient total light transmittance and frontal brightness, but its haze is low, so the light diffusibility is not sufficient, and the shape of the light source cannot be completely erased. It turns out that it does not have a function to do. Furthermore, the light diffusion sheet of Comparative Example 1-5 in which only a light-collecting layer is formed on a conventionally known polycarbonate light diffusion plate of Comparative Example 1-5 or a transparent film (used in combination with a conventionally known polycarbonate light diffusion plate) is a light source. Since the shape of the light source can be completely erased, it has the function of using a line light source as a surface light source, but it is not satisfactory as a light diffusing sheet with low light diffusivity and front brightness! /.

(2) In the following Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-6, in order to obtain a light diffusing sheet having high performance, a light transmissive film constituting the light diffusing layer is used. If the absolute value of the difference in refractive index between the fat and at least one type of fine particle group (fine particle group A) is 0.05 or more, the condition is necessary, and in particular, it has excellent scratch resistance and fine particle shedding. In order to obtain a light diffusion sheet, it is necessary that the translucent resin constituting the light diffusion layer is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles. Prove that. In the following Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-6, the light diffusion layer in which the fine particle groups A and B are dispersed in the light-transmitting resin is a light diffusion layer. It means the light collecting layer.

[0218] First, a method for measuring physical properties of elements constituting the light diffusion sheet and a method for evaluating the performance of the light diffusion sheet will be described.

[0219] <Average particle size of fine particle group>

The average particle size of the fine particle group is a volume average particle size measured using a particle size distribution analyzer (Multisizer II type, manufactured by Coulter Co., Ltd.).

[0220] <Layer thickness of light diffusion layer> The layer thickness of the light diffusing layer is the average value of the measured values obtained by measuring the layer thickness at 5 or more points for each sample using a thickness meter (Dial Thickness Gauge, manufactured by Ozaki Manufacturing Co., Ltd.). .

[0221] <Refractive index of translucent resin>

The refractive index of the translucent resin constituting the light diffusing layer is the isocyanate group (Desmodur N3200, manufactured by Sumika Bayer Urethane Co., Ltd.), a hydroxyl group (OH group) of the translucent resin and a polyfunctional isocyanate compound (manufactured by Sumika Bayer Urethane Co., Ltd.) After adding the polyfunctional isocyanate compound to the translucent resin so that the NCO group) becomes OH group ZNCO group = 1 (equivalent ratio), a 40 m thick film is used using a bar coater The refractive index of this film was measured with a multiwavelength Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.). The measurement wavelength was 589.3 nm and the measurement temperature was 25 ° C.

[0222] <Refractive index of fine particle group A>

The refractive index of the fine particle group A dispersed in the translucent resin constituting the light diffusion layer is determined by several types of Cargill standard refraction liquids (standard series, manufactured by Moritex Corp .; refractive index range n ²⁵ =

D

1. Prepare 300-2.11), place microparticles group A on a slide glass, add a standard refractive solution with the expected refractive index, sandwich it with a cover glass, and then use a transmission optical microscope at 25 ° C. (Digital microscope VHX-200, manufactured by Keyence Corporation; the light source lamp is a 12V, 100W, Rogen lamp (color temperature 3, 100K (at maximum light intensity))). The refractive index of the standard refractive liquid used when the interface with the quasi-refractive liquid is most difficult to see is defined as the refractive index of the fine particle group A. However, if there are two types of standard refractive liquids that have a continuous refractive index when the interface between the fine particle group A and the standard refractive liquid is most difficult to see, the intermediate value of these refractive indices is set to the refractive index of the fine particle group A. In addition, when the refractive index of the fine particle group A is outside the refractive index range of the Cargill standard refraction liquid, the refractive index of the material is taken as the refractive index of the fine particle group A.

[0223] <Surface roughness of light diffusion layer>

The surface roughness of the light diffusing layer was obtained by measuring the arithmetic average roughness at 5 or more locations randomly selected for each sample using a surface roughness meter (Dektak3030, manufactured by Nippon Vacuum Technology Co., Ltd.). The average value of the measured values.

[0224] <Total light transmittance and haze>

The total light transmittance and haze of the sample were measured using a turbidimeter (NDH-1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.). [0225] <Front brightness>

[0226] Measuring method:

A 2 mm-thick polycarbonate transparent support was placed 5 mm away from the surface of the cold cathode tube, and a sample was placed on it. A luminance meter (BM-7, manufactured by Topcon Co., Ltd.) was fixed at a position 50 cm away from the sample, and the luminance on the light source was measured.

[0227] <Light source shape>

When measuring the front luminance, the shape of the light source was visually observed and evaluated according to the following criteria. ◯: The power source shape could not be confirmed;

Δ: The light source shape is blurred;

X: The light source shape was clearly confirmed.

[0228] <Scratch resistance>

The scratch resistance was evaluated using a friction tester (FR-2 type, manufactured by Suga Test Instruments Co., Ltd.). First, a polyethylene terephthalate (PET) film (Cosmo Chain A-4300, manufactured by Toyobo Co., Ltd .; thickness 100 / zm) was installed on the friction surface of the friction tester, and a light diffusion layer was placed on top of it. A light diffusing sheet was placed so as to face, a load of 200 g was applied, and the friction element was reciprocated 10 times. After that, the occurrence of scratches on the surface of the light diffusion sheet is observed with an optical microscope (450 times), and the occurrence of scratches on the surface of the PET film is visually observed. Was evaluated according to the following criteria.

◎: No damage was observed

◯: A strong wound was observed;

Δ: considerable scratches observed;

X: Significant scratches were observed.

[0229] <Particle shedding>

The detachability of the fine particle group was evaluated using a friction tester (FR-2, manufactured by Suga Test Instruments Co., Ltd.). First, a non-woven fabric (Bencott, manufactured by Asahi Kasei Co., Ltd.) was placed on the frictional sliding surface of the friction tester, and a light diffusion sheet was placed on top of it so that the light diffusion layer was opposed to it. Or And made 10 round trips. Thereafter, the adhesion state of the drop-off particles on the surface of the nonwoven fabric was observed with an optical microscope (450 times), and the drop-off property of the light diffusion sheet was evaluated according to the following criteria.

◎: Dropping fine particles were not observed at all;

◯: A small amount of shed particles was observed;

Δ: A small amount of shed particles was observed;

X: A large amount of falling fine particles was observed.

[0230] Next, the (meth) acrylic resin (hereinafter referred to as "copolymer A" or "copolymer B") or organic-inorganic composite used in the examples and comparative examples. A method for preparing ultrafine particles will be described.

[0231] <Preparation of copolymer A>

100 parts by mass of butyl acetate was added as a solvent to four Roflascos equipped with a stirrer, thermometer, cooler, dropping funnel and nitrogen gas inlet tube, and the temperature was raised to the reflux temperature. Next, while introducing nitrogen gas, 40 parts by weight of cyclohexyl methacrylate as a monomer, butanol methacrylate 37.7 mass 咅 ^ butynole acrylate 7.3 mass 咅 ^ 2 It consists of 13.9 parts by weight of tacrylate, 1.1 parts by weight of methacrylic acid, and 3.0 parts by weight of t-butylperoxy 2-ethylhexanoate (trade name Perbutyl 0, manufactured by Nippon Oil & Fats Co., Ltd.) as a polymerization initiator. The monomer mixture was dropped from the dropping funnel over 3 hours. Furthermore, 1,1-bis (t-butylperoxy) 1,3,3,5 trimethylcyclohexane (trade name Perhexa 3M, manufactured by NOF Corporation) 0.2 part by mass is added 3 times at 30 minute intervals And held at reflux temperature for 2 hours. Thereafter, the reaction solution was cooled to room temperature to obtain a copolymer A solution. The resulting copolymer A had a solid content concentration of 50.3%. The molecular weight of copolymer A was number average molecular weight (Mn) Z weight average molecular weight (Mw) = 5,300 / 10,500. Formula power of FOX The calculated theoretical glass transition temperature was 40 ° C, and the theoretical hydroxyl value was 60.

[0232] <Preparation of copolymer B>

In the preparation of copolymer A, the composition of the monomer contained in the monomer mixture was changed to 37.2 parts by mass of methyl metatalylate, 39.3 parts by mass of butyl metatalylate, 2 ethylhexyl Copolymer B was prepared in the same manner as Copolymer A, except that 8.5 parts by weight of tallylate, 13.9 parts by weight of hydroxyethyl methacrylate, and 1.1 parts by weight of methacrylic acid were used. A solution was obtained. The resulting copolymer B had a solid content concentration of 50.1%. The molecular weight of copolymer B was number average molecular weight (Mn) Z weight average molecular weight (Mw) = 5,700 / 10,200. Formula force of FOX The calculated theoretical glass transition temperature was 40 ° C, and the theoretical hydroxyl value was 60.

[0233] <Preparation of organic-inorganic composite ultrafine particles>

Organic inorganic composite ultrafine particles in which an organic polymer ((meth) acrylic resin) is fixed on the surface of inorganic ultrafine particles (silica) according to the method described in JP-A-11-5940, paragraphs 0056 to 0061 (Hereinafter, sometimes simply referred to as “composite ultrafine particles”) was obtained in a dispersion in butyl acetate. The concentration of the composite ultrafine particles was 30.0% by mass, and the inorganic content in the composite ultrafine particles was 57.8% by mass. The composite ultrafine particles had an average particle size of 55 nm and a coefficient of variation of 18.0%. The alkoxy group present in the composite ultrafine particles contained 0.12 mol / g of methoxy group. The composite ultrafine particles also had good stability over time. The force obtained by analyzing the supernatant obtained by centrifuging this composite ultrafine particle dispersion by gel permeation chromatography (GPC) showed that no organic polymer was detected. In addition, each composite ultrafine particle, which is a sediment after centrifugation of the composite ultrafine particle dispersion, was washed with tetrahydrofuran or water, and the washing was analyzed by gel permeation chromatography (GPC). No power was detected. The above results indicate that in the composite ultrafine particles, the organic polymer is firmly fixed rather than simply adhering to the inorganic ultrafine particles.

[0234] The composite ultrafine particle concentration was calculated by the following formula after drying the composite ultrafine particle dispersion at 130 ° C for 24 hours under a pressure of 1.33 X 10 ⁴ Pa (100 mmHg).

Composite ultrafine particle concentration (mass%) = 100 X D / W

[Wherein D represents the mass (g) of the composite ultrafine particles after drying, and W represents the mass (g) of the composite ultrafine particle dispersion before drying]

The inorganic content in the composite ultrafine particles was determined by elemental analysis of the composite ultrafine particle dispersion dried at 130 ° C for 24 hours under a pressure of 1.33 X 10 ⁴ Pa (100 mmHg) It was set as the inorganic content in the composite ultrafine particles.

[0235] The average particle size of the composite ultrafine particles was measured at 23 ° C by a dynamic light scattering measurement method using a submicron particle size analyzer (NICOMPMO DEL370, manufactured by Nozaki Sangyo Co., Ltd.). The measured average particle diameter is a volume average particle diameter. The measurement sample was a composite ultrafine particle dispersion dispersed in tetrahydrofuran having a composite ultrafine particle concentration of 0.1 to 2.0% by mass (if the organic polymer in the composite ultrafine particles does not dissolve in tetrahydrofuran, the organic polymer Dispersed in a solvent in which one is dissolved).

[0236] The coefficient of variation of the average particle diameter of the composite ultrafine particles was calculated by the following equation.

Coefficient of variation (%) = Standard deviation of particle diameter of composite ultrafine particles Z Average particle diameter of composite ultrafine particles The content of alkoxy groups in composite ultrafine particles is 1.33 X 10 ⁴ Pa (lOOmmHg) 5 g of composite ultrafine particles dried at 130 ° C for 24 hours under a pressure of 50 μg of acetone and 50 g of 2N-NaOH aqueous solution was dispersed in the mixture and stirred at room temperature for 24 hours. The alcohol was quantitatively calculated.

[0237] The composite ultrafine particles are stable over time by sealing the composite ultrafine particle dispersion in a Gardner viscosity tube and storing it at 50 ° C for 1 month, then agglomeration and sedimentation of the composite ultrafine particles, increase in viscosity, etc. What was not recognized was set as "good".

[Example 2-1]

By mixing 27 parts by mass of the copolymer A solution obtained above with 100 parts by mass of the butyl acetate dispersion of the composite ultrafine particles obtained above, the inorganic substance content in the solid content force S40% by mass Thus, a translucent resin solution containing the copolymer A and the composite ultrafine particles was obtained. The refractive index of the translucent resin was 1.51.

[0239] In this translucent resin solution, as fine particle group A, spherical fine particles of benzoguanamine 'formaldehyde condensate (Epester MS, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.66, average particle size 1.6 / zm) is 30% by mass with respect to the translucent resin solution, and as microparticles group B, spherical microparticles of polymethyl methacrylate-based crosslinked product (Epaster MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1. 51, An average particle diameter of 13.5 m) was added to 70% by mass with respect to the translucent resin solution. Thereafter, a polyfunctional isocyanate compound (Desmodur N3200, manufactured by Sumika Bayer Urethane Co., Ltd.) was weighed and added to this mixture in an amount such that OH group ZNCO group = 1 (equivalent ratio). . The obtained resin composition was coated on a polyethylene terephthalate film (Cosmo Shine A-4300, manufactured by Toyobo Co., Ltd .; thickness 100 m) as a transparent film using a bar coater. After standing for a period of time, it was dried at 80 ° C. for 2 hours to obtain a light diffusion sheet having a light diffusion layer having a thickness of 25 m. The absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.15, and the surface roughness of the light diffusion layer was 1.55 / zm.

[0240] The total light transmittance and haze of the obtained light diffusion sheet were 71% and 93%, respectively. The front luminance was 7,253 cdZm ² and the light source shape could not be confirmed. These results and the performance of the light diffusion sheet are shown in Table 2.

[0241] <Example 2-2>

In Example 2-1, except that the solution of the copolymer B obtained above was used instead of the solution of the copolymer A, a translucent resin solution was prepared. In the same manner as described above, a light diffusion sheet having a light diffusion layer with a thickness of 24 / zm was obtained. The refractive index of the translucent resin was 1.51. The absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.15, and the surface roughness of the light diffusion layer was 1.52 / zm.

[0242] The total light transmittance and haze of the obtained light diffusion sheet were 70% and 94%, respectively. In addition, the front luminance was 7,186 cdZm ² , and the shape of the light source could not be confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[0243] Example 2-3

In Example 2-1, titanium oxide fine particles (TIPAQUE CR-95, manufactured by Ishihara Sangyo Co., Ltd .; average particle size 250 nm) as fine particle group A were added to the translucent resin solution. As a fine particle group B, a spherical particle of polymethyl methacrylate-based cross-linked product (Epester MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 13.5 / zm) is passed through. A light diffusing sheet having a light diffusing layer having a thickness of 26 m was obtained in the same manner as in Example 2-1, except that 70% by mass was added to the light waving solution. The absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and the fine particle group A was 1.20, and the surface roughness of the light diffusion layer was 1.49 / zm. [0244] The total light transmittance and haze of the obtained light diffusion sheet were 46% and 92%, respectively. In addition, the front luminance was 4,658 cdZm ² , and the light source shape could not be confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[Example 2-4]

In Example 2-1, spherical fine particles of benzoguanamine 'formaldehyde condensate as fine particle group A (Poster MS, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.66, average particle size 1. 6 m) was added in an amount of 30% by mass with respect to the translucent resin solution, but as fine particle group B, spherical particles of polymethyl methacrylate-based crosslinked product (Epester MA10 13, manufactured by Nippon Shokubai Co., Ltd .; refractive index) 1. A light diffusing sheet having a light diffusing layer having a thickness of 23 m was obtained in the same manner as in Example 2-1, except that 1.51 and an average particle size of 13.5 m) were added. The absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.15, and the surface roughness of the light diffusion layer was 0.49 m.

[0246] The total light transmittance and haze of the obtained light diffusing sheet were 79% and 93%, respectively. The front luminance was 6,621 cd / m ² , and the shape of the light source could not be confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[Example 2-5]

In Example 2-1, the translucent resin solution was mixed with acid zinc fine particles (LPZINC-2, manufactured by Sakai Chemical Industry Co., Ltd .; refractive index 1.95, average particle size m) as the fine particle group A. 20% by mass with respect to the translucent rosin solution, and as microparticles group B, spherical microparticles of polymethyl methacrylate-based cross-linked product (Epaster MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 13 A light diffusion sheet having a light diffusion layer having a thickness of 22 m was prepared in the same manner as in Example 2-1, except that 70% by mass of 5 μm) was added to the translucent resin solution. Obtained. The absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.44, and the surface roughness of the light diffusion layer was 1.48 m.

[0248] The total light transmittance and haze of the obtained light diffusion sheet were 70% and 90%, respectively. In addition, the front luminance was 7,013 cd / m ² , and the shape of the light source could not be confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[0249] << Comparative Example 2-1 >> In Example 2-1, the thickness of the film was changed in the same manner as in Example 2-1, except that the translucent resin solution was prepared without adding the composite ultrafine particles to the copolymer A solution. A light diffusion sheet having a light diffusion layer of 24 m was obtained. The absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.17, and the surface roughness of the light diffusion layer was 1.53 / zm.

[0250] The total light transmittance and haze of the obtained light diffusion sheet were 70% and 91%, respectively. In addition, the front luminance was 7,213 cd / m ² , and the shape of the light source could not be confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[0251] Comparative Example 2-2

In Example 2-2, a thickness of 26 m was obtained in the same manner as in Example 2 except that the translucent resin solution was prepared without adding the composite ultrafine particles to the copolymer B solution. A light diffusing sheet having a light diffusing layer was obtained. The absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.05, and the surface roughness of the light diffusion layer was 1.

[0252] The total light transmittance and haze of the obtained light diffusion sheet were 70% and 92%, respectively. In addition, the front luminance was 7,159 cdZm ² , and the shape of the light source could not be confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[0253] <Comparative Example 2-3>

In Example 2-3, the thickness was changed in the same manner as in Example 2-3 except that the translucent resin solution was prepared without adding the composite ultrafine particles to the copolymer A solution. A light diffusing sheet having a light diffusing layer was obtained. The absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and the fine particle group A was 1.22, and the surface roughness of the light diffusion layer was 1.

[0254] The total light transmittance and haze of the obtained light diffusion sheet were 45% and 92%, respectively. In addition, the front luminance was 4,523 cdZm ² , and the shape of the light source could not be confirmed. Table 1 shows these results and the performance of the light diffusion sheet.

[0255] << Comparative Example 2-4 >>

In Example 2-5, the thickness was determined in the same manner as in Example 2-5, except that the translucent resin solution was prepared without adding the composite ultrafine particles to the copolymer A solution. A light diffusion sheet having a 21 μm light diffusion layer was obtained. The absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.46, and the surface roughness of the light diffusion layer was 1.46 m. [0256] The total light transmittance and haze of the obtained light diffusion sheet were 71% and 88%, respectively. In addition, the front luminance was 7,002 cd / m ² , and the shape of the light source could not be confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[0257] << Comparative Example 2-5 >>

In Example 2-1, spherical particles of poly (methacrylic acid) methyl-based cross-linked product as fine particle group A in a translucent resin solution (Epaster MA1004, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle) The diameter of 4.3 m is 30% by mass with respect to the translucent resin solution, and the fine particle group B is a spherical particle of polymethyl methacrylate-based crosslinked product (Epaster MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1 A light diffusion layer having a thickness of 24 m was obtained in the same manner as in Example 2-1, except that 70% by mass of 51, average particle size of 13.5 m) was added to the translucent resin solution. A light diffusing sheet having The absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.00, and the surface roughness of the light diffusion layer was 1.58 / zm.

[0258] The total light transmittance and haze of the obtained light diffusion sheet were 75% and 90%, respectively. The front luminance was 9,012 cdZm ² , and the light source shape was clearly confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[0259] Comparative Example 2-6

In Example 2-4, spherical fine particles of polymethacrylic acid methyl-based cross-linked product as a fine particle group A in a translucent resin solution (Epaster MA1004, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle A spherical particle of polymethyl methacrylate-based bridge as force particle group B with 4.3 m diameter added (Epaster MA1013, manufactured by Nippon Shokubai Co., Ltd .; refractive index 1.51, average particle size 13.5 A light diffusing sheet having a light diffusing layer having a thickness of 22 m was obtained in the same manner as in Example 2-4, except that m) was not added. The absolute value of the difference in refractive index between the translucent resin constituting the light diffusion layer and the fine particle group A was 0.00, and the surface roughness of the light diffusion layer was 0.78 m.

[0260] The total light transmittance and haze of the obtained light diffusion sheet were 78% and 85%, respectively. The front luminance was 9, 312 cdZm ² and the light source shape was clearly confirmed. Table 2 shows these results and the performance of the light diffusion sheet.

[0261] [Table 2]

[0262] As is apparent from Table 2, the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group (fine particle group A) is 0.05 or more. The light diffusing sheets of Examples 2-1 to 2-5 satisfying the above conditions exhibit a sufficient total light transmittance, high haze, sufficient front luminance, and can completely erase the shape of the light source. In addition, since it has a function of using a line light source as a surface light source, it has a remarkable light diffusivity and light condensing property as a light diffusion sheet. In addition, the translucent resin constituting the light diffusion layer is a resin containing (meth) acrylic resin and organic-inorganic composite ultrafine particles, and has excellent scratch resistance. During storage, the light diffusing sheet and the contact member will not be damaged, and the particles that make up the light diffusing layer will not fall off.Manufacturing, storage, transportation, use, etc. It is easy to handle and it can be seen that the yield is improved.

[0263] On the other hand, the condition that the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group (microparticle group A) is 0.05 or more is satisfied. Comparative Example 2-1 to 2-4 The light diffusing sheet has sufficient total light transmittance, front luminance and haze, and can completely erase the shape of the light source, and the function of using a linear light source as a surface light source Therefore, the light diffusing sheet has sufficient light diffusibility and light collecting property, but the translucent resin constituting the light diffusing layer does not contain inorganic ultrafine particles or organic-inorganic composite ultrafine particles. ! ヽ (Meth) acrylic resin, inferior in scratch resistance and fine particle shedding, so it is not practical as a light diffusion sheet that is not easy to handle during production, storage, transportation, use, etc. I understand that. Further, if the absolute value of the refractive index difference between the translucent resin constituting the light diffusion layer and at least one kind of fine particle group (fine particle group A) is 0.05 or more, the above condition is not satisfied! The light diffusing sheets of Comparative Examples 5 and 6 have good or comparatively good scratch resistance and fine particle shedding, but the shape of the light source is good despite showing sufficient total light transmittance, front luminance, and haze. Is not practical as a light diffusing sheet because it cannot be completely extinguished and does not have a function of using a line light source as a surface light source.

Industrial applicability

[0264] The light diffusing sheet and the light diffusing plate of the present invention can completely erase the light source shape and have a function of using a line light source as a surface light source. While maintaining the basic optical properties of providing light transmittance and brightness The number of components of the knocklight unit can be reduced, and the force is excellent in the scratch resistance of the light diffusion layer, the handling is easy, and the yield is improved. It makes a great contribution to the reduction.

Claims

The scope of the claims

[1] A light diffusing sheet in which a light diffusing layer in which at least one kind of fine particle group is dispersed is formed on at least one surface of a transparent film, and the light transmissive layer constituting the light diffusing layer A light diffusing sheet, characterized in that the absolute value of the difference in refractive index between the synthetic resin and at least one kind of fine particle group is 0.05 or more.

[2] At least one of the light diffusion layers contains two kinds of fine particle groups, and the surface roughness of the light diffusion layer is not less than 0.5 μm and not more than 7 μm in arithmetic mean roughness. The light diffusion sheet according to 1.

[3] A light diffusion layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one surface of the transparent film, and at least one kind of transparent resin is formed on the light diffusion layer. 2. The light diffusing sheet according to claim 1, wherein a light condensing layer in which fine particle groups are embedded is formed, and the surface roughness of the light condensing layer is an arithmetic average roughness of 0.5 μm or more and 7 μm or less.

[4] A light diffusion layer in which at least one type of fine particle group is dispersed in a transparent resin is formed on one side of the transparent film, and at least one type of transparent resin is formed on the opposite surface of the transparent film. The light diffusing sheet according to claim 1, wherein a light condensing layer in which a group of fine particles is embedded is formed, and the surface roughness of the light condensing layer is not less than 0 and not more than 7 m in terms of arithmetic average roughness.

5. The light diffusing sheet according to any one of claims 1 to 4, wherein the translucent resin is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles.

[6] A light diffusing layer in which at least one kind of fine particle group is dispersed is formed on at least one surface of the transparent support, and at least 1 A light diffusing plate, characterized in that the absolute value of the difference in refractive index from a group of fine particles is 0.05 or more

[7] A light diffusing sheet in which a light diffusing layer in which at least one kind of fine particle group is dispersed in one side of a transparent film is formed on one side of a transparent film is an adhesive or an adhesive on at least one side of the transparent support. A light diffusing plate, characterized in that the absolute value of the difference in refractive index between the translucent resin and the at least one kind of fine particles that are bonded together and constitute the light diffusing layer is 0.05 or more.

[8] At least one of the light diffusion layers contains two kinds of fine particle groups, and the surface roughness of the light diffusion layer is not less than 0.5 μm and not more than 7 μm in arithmetic mean roughness. 6 or 7 Light diffusion plate.

[9] A light diffusing layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one surface of the transparent support, and at least one kind of transparent resin is formed on the light diffusing layer. The light diffusing plate according to claim 6, wherein a light condensing layer in which the fine particle group is embedded is formed, and the surface roughness of the light condensing layer is an arithmetic average roughness of 0.5 μm or more and 7 μm or less. .

[10] A light diffusing layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on one surface of the transparent support, and at least the translucent resin is formed on the opposite surface of the transparent support. 7. The light diffusing plate according to claim 6, wherein a light condensing layer in which one kind of fine particle group is embedded is formed, and the surface roughness of the light condensing layer is an arithmetic average roughness of not less than 0 and not more than 7 m. .

[11] A light diffusion layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one side of the transparent support, and at least one kind of transparent resin is provided on one side of the transparent film. A condensing sheet having a condensing layer in which fine particles are embedded is attached to the opposite surface of the transparent support with an adhesive or an adhesive, and the surface roughness of the condensing layer is an arithmetic average roughness. The light diffusing plate according to claim 6, which is 0.5 μm or more and 7 μm or less.

[12] A light diffusing layer in which at least one kind of fine particle group is dispersed in a transparent resin is formed on one side of the transparent film, and at least one kind of fine particles in the light transmitting resin is formed on the light diffusing layer. A light diffusing sheet on which a condensing layer in which a group is embedded is formed is bonded to one side of the transparent support with an adhesive or an adhesive, and the surface roughness of the condensing layer is 0 in terms of arithmetic average roughness. The light diffusing plate according to claim 7, which is 7 m or less.

[13] A light diffusing sheet in which a light diffusing layer in which at least one kind of fine particle group is dispersed in a translucent resin is formed on one side of a transparent film is attached to one side of the transparent support with an adhesive or an adhesive. And a condensing layer in which at least one type of fine particle group is embedded in a transparent resin is formed on the opposite surface of the transparent support, and the surface roughness of the condensing layer is an arithmetic average roughness. 8. The light diffusing plate according to claim 7, which is 0.5 μm or more and 7 μm or less.

[14] A light diffusing sheet in which a light diffusing layer in which at least one kind of fine particle group is dispersed in one side of a transparent film is formed on one side of a transparent film is attached to one side of the transparent support with an adhesive or an adhesive. And a condensing sheet having a condensing layer in which at least one kind of fine particle group is embedded in a transparent resin is formed on one side of the transparent film. 8. The light diffusing plate according to claim 7, wherein the light diffusing plate is attached with an adhesive, and the surface roughness of the light condensing layer is not less than 0.

[15] The light diffusing plate according to any one of [6] to [14], wherein the translucent resin is a (meth) acrylic resin containing inorganic ultrafine particles or organic-inorganic composite ultrafine particles.

[16] A knocklight unit comprising a light source, a reflective sheet, a transparent support, and the light diffusion sheet according to any one of claims 1 to 5.

[17] A backlight unit comprising a light source, a reflection sheet, and the light diffusion sheet according to any one of claims 1 to 5.

[18] A knock light unit comprising a light source, a reflective sheet, and the light diffusing plate according to any one of claims 6 to 15.

[19] A liquid crystal display device comprising the backlight unit according to any one of claims 16 to 18.