WO2009148190A1

WO2009148190A1 - Antistatic light diffuser plate

Info

Publication number: WO2009148190A1
Application number: PCT/JP2009/060649
Authority: WO
Inventors: 濱松豊博
Original assignee: 住友化学株式会社
Priority date: 2008-06-05
Filing date: 2009-06-04
Publication date: 2009-12-10
Also published as: JP2009294441A; TW201011352A

Abstract

Provided is an antistatic light diffuser plate wherein a surface (6a) treated by corona discharge is formed at least on one surface of a light diffusing resin board (6) containing a transparent resin.

Description

Antistatic Light Diffuser Technical Field

The present invention provides a light diffusing substrate suitable for uniformly applying a solution containing an antistatic agent, and the formation of a uniform antistatic coating layer, which can sufficiently prevent adhesion of dust and the like and is used for a direct type backlight. The present invention relates to a suitable light diffusion plate.

In this specification and claims, the term “water contact angle” refers to the contact of pure water with the surface of the resin board measured according to JISK 6 7 6 8 — 1 9 9 9. Means a corner. Background art

A known liquid crystal display device has a configuration in which a direct backlight is disposed on the back side of a liquid crystal panel (image display unit). As the direct type backlight, there is known a configuration in which a plurality of light sources are arranged in front of a light reflecting plate and a light diffusing plate is arranged on the front side of these light sources (Patent Document 1 “Special Features”). Open 2 0 0 4 — 1 7 0 9 3 7 ”). '' In recent years, the size of liquid crystal display devices, especially liquid crystal televisions, has been rapidly increasing. If the number of light sources is increased in order to increase the screen size and ensure sufficient brightness, the amount of heat generated by the light sources will increase greatly. End up. Therefore, when the screen is enlarged, it is required to discharge the heat generated inside more efficiently.

In direct type backlight devices, fans are often installed to exhaust heat. Cooling is performed by blowing air from the exhaust heat fan and replacing the air inside the direct backlight unit. However, when air is blown in this way, there is a problem that dust or the like easily adheres to the surface of the light diffusion plate. If dust or the like adheres to the surface of the light diffusing plate, there is a concern that the image may be disturbed or the sharpness or brightness of the image may be reduced.

In order to prevent such dust adhesion, the light diffusion plate has excellent antistatic performance. , It is required to be.

Therefore, it has been proposed to form an antistatic coating layer on the surface of the light diffusion plate by applying an antistatic agent aqueous solution to the surface of the light diffusion plate made of synthetic resin so that the light diffusion plate has antistatic performance. (Patent Document 2 “Japanese Unexamined Patent Publication No. 2 0 06 _ 3 3 0 5. 46”, Patent Document 3 “Japanese Unexamined Patent Application Publication No. 2 0 7-7 1 7 8 5 4 4”, Patent Document 4 “JP 2 0 0 8— 1 9 4 1 1 ”). Disclosure of the invention

However, when an antistatic agent aqueous solution is applied to the surface of a synthetic resin light diffusing plate, the antistatic agent aqueous solution is not likely to spread uniformly on the surface, and unevenness in the application of the antistatic agent is likely to occur. As a result, there is a concern that the prevention of dust adhesion is partially insufficient. As a result of the inventor's investigation, in particular, when the aqueous solution of an antistatic agent is applied to a light diffusion plate made of a propylene polymer, unevenness in the density of the application of the antistatic agent tends to occur remarkably. It was.

The present invention has been made in view of such a technical background, and when a solution containing an antistatic agent is applied, the light diffusion substrate can be applied uniformly and unevenness in coating is less likely to occur. An object of the present invention is to provide an antistatic light diffusing plate that can sufficiently prevent dust and the like from adhering to the entire surface. It is another object of the present invention to provide a liquid crystal display device capable of displaying a good image with which dust or the like hardly adheres to the surface of the light diffusion plate.

In order to achieve the above object, the present invention provides the following means.

[1] A light diffusing substrate having a corona discharge treatment on at least one surface of a light diffusing resin plate containing a transparent resin.

[2] The light diffusion substrate according to [1], wherein the transparent resin is a propylene polymer or a styrene polymer.

[3] A light diffusing substrate in which a resin containing a propylene polymer forms at least one surface, and a water contact angle on the surface is 90 ° or less.

[4] A light diffusing substrate in which a resin containing a styrene polymer forms at least one surface, and a water contact angle on the surface is 60 ° or less.

[5] On the corona discharge-treated surface of the light diffusing substrate according to [1] or [2], A light diffusion plate in which a coating layer containing an antistatic agent is laminated.

[6] A light diffusing plate in which a coating layer containing an antistatic agent is laminated on the surface of the light diffusing substrate according to the above [3] having a water contact surface of 90 ° or less.

[7] A light diffusing plate in which a coating layer containing an antistatic agent is laminated on the surface of the light diffusing substrate according to the above [4] whose water contact surface is 60 ° or less.

[8] The light according to any one of [5] to [7], wherein the coating layer is formed by applying a solution containing an antistatic agent to a light diffusion substrate and drying the solution. Diffusion plate.

[9] Use of the light diffusing plate according to any one of [5] to [8] as a component in a direct backlight.

[10] A direct backlight comprising the light diffusing plate according to any one of [5] to [8], and a plurality of light sources arranged on the back side of the light diffusing plate.

[11] The light diffusing plate according to any one of [5] to [8], a plurality of light sources arranged on the back side of the light diffusing plate, and the front side of the light diffusing plate A liquid crystal display device comprising a liquid crystal panel.

In the invention of [1], corona discharge treatment is performed on at least one surface of the light diffusing resin plate containing the transparent resin, so if a solution containing an antistatic agent is applied to the corona discharge treatment surface, It can be applied evenly (that is, the density unevenness of the application of the antistatic agent is suppressed), and therefore a uniform antistatic coating layer is formed, so that light that can sufficiently prevent the adhesion of dust etc. over the entire surface. A diffuser plate is provided.

In the invention of [2], the transparent resin is a propylene polymer or a styrene polymer, and a solution containing an antistatic agent can be uniformly applied using a material suitable as a light diffusion plate. Therefore, since a uniform antistatic coating layer is formed, the light diffusing plate capable of sufficiently preventing the adhesion of dust or the like over the entire surface is provided.

In the invention of [3], since the resin containing the propylene polymer forms at least one surface and the water contact angle of the surface is 90 ° or less, the solution containing the antistatic agent on the surface Can be applied uniformly (ie, the uneven density of the application of the antistatic agent is suppressed), and thus a uniform antistatic coating layer is formed. Thus, a light diffusing plate that can sufficiently prevent adhesion of dust and the like over the entire surface is provided.

In the invention of [4], since at least one surface containing the styrene polymer contains at least one surface, and the water contact angle on the surface is 60 ° or less, the solution containing the antistatic agent on the surface Can be applied uniformly (that is, the uneven density of the antistatic agent applied is suppressed), and therefore a uniform antistatic coating layer is formed, so that the adhesion of dust and the like can be sufficiently prevented over the entire surface. A light diffusion plate is provided.

In the invention of [5], since a coating layer containing an antistatic agent is laminated on the corona discharge-treated surface of the light diffusion substrate of [1] or [2], a uniform antistatic coating layer is formed. Accordingly, it is possible to sufficiently prevent the dust from adhering to the light diffusion plate over the entire surface.

In the invention of [6], since the coating layer containing the antistatic agent is laminated on the surface of the light diffusing substrate of [3] having a water contact angle of 90 ° or less, a uniform antistatic coating is provided. Therefore, it is possible to sufficiently prevent the dust from adhering to the light diffusing plate over the entire surface.

In the invention of [7], since the coating layer containing the antistatic agent is laminated on the surface of the light diffusing substrate of the above [4] having a water contact angle of 60 ° or less, a uniform antistatic coating Therefore, it is possible to sufficiently prevent the dust from adhering to the light diffusing plate over the entire surface.

In the invention of [8], the coating layer is formed by applying a solution containing an antistatic agent to the light diffusion substrate of any one of the above ““ 5 ”to“ 7 ”and drying it. Provided is a light diffusing plate that can sufficiently prevent the adhesion of dust or the like over the entire surface.

The invention of [9] provides a use as a part of a direct backlight plate of a light diffusing plate excellent in antistatic performance that can sufficiently prevent adhesion of dust or the like over the entire surface.

In the invention of [10], the light diffusing plate constituting the direct type backlight has uniform antistatic performance over the entire surface, so that high-brightness backlight light can be secured over a long period of time.

In the invention of [1 1], since the light diffusing plate constituting the liquid crystal display device has uniform antistatic performance over the entire surface, high quality and high quality images ( In other words, it is possible to display a sharp and high-brightness image that is less likely to be disturbed. Brief Description of Drawings

FIG. 1 is a sectional view showing an embodiment of a light diffusion substrate according to the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of a light diffusing plate according to the present invention.

FIG. 3 is a schematic sectional view showing an embodiment of the liquid crystal display device according to the present invention. FIG. 4 is a sectional view showing another embodiment of the light diffusing plate according to the present invention.

Explanation of symbols

1 ... Light diffusion plate

2 ... Light diffusion substrate

3… Coating layer ''

6… Light diffusing resin plate

6 a ... Corona discharge treated surface

3 0… Liquid crystal display device

3 1… Direct backlight

3 2… Light source

3 8 ... Liquid crystal panel Embodiment for carrying out the invention

One embodiment of the light diffusion substrate (2) according to the present invention is shown in FIG. In this light diffusion substrate (2), a corona discharge treatment is performed on one side of a light diffusion resin plate (6) containing a transparent resin. That is, one side is the corona discharge treatment surface (6a). In the present embodiment, a laminated plate in which the surface layers (2 2) and (2 2) are laminated on both sides of the base layer (2 1) is used as the light diffusing resin plate (6). Of course, the light diffusing resin plate (6) may be composed of a single layer (see FIG. 4). In this embodiment, a configuration in which corona discharge treatment is applied to only one surface of the light diffusing resin plate (6) is adopted, but corona discharge treatment is applied to both surfaces of the light diffusing resin plate (6). Then, a configuration in which both surfaces are formed on the corona discharge treatment surface (6a) (6a) may be adopted (see FIG. 4). In the light diffusing substrate (2) having the above configuration, at least one surface is formed on the corona discharge treatment surface (6 a). Therefore, a solution containing an antistatic agent is applied to the corona discharge treatment surface (6 a). If applied, it can be applied uniformly while suppressing unevenness in the application of the antistatic agent, that is, a uniform antistatic coating layer (3) can be formed, so that adhesion of dust etc. is sufficient over the entire surface. It is possible to provide a light diffusing plate (1) that can be prevented easily (see Fig. 2).

The treatment conditions of the corona discharge treatment are not particularly limited, but the moving speed (line speed) when the light diffusing resin plate (6) to be treated passes through the corona discharge region is determined. It is preferably set to 1 to 20 mZ. The applied power for the corona discharge treatment is preferably set to 100 to 100 W, and particularly preferably set to 150 to 900 W.

By performing such corona discharge treatment, for example, in the light diffusing resin plate (6) containing a propylene polymer, the water contact angle of the surface (corona discharge treatment surface) can be reduced to 90 ° or less. In addition, in the light diffusing resin plate (6) containing a styrene polymer, the water contact angle of the surface (corona discharge treatment surface) can be made 60 ° or less. Thus, the corona discharge treatment can reduce the water contact angle of the surface (corona discharge treatment surface). Therefore, if a solution containing an antistatic agent is applied to the corona discharge treatment surface (6a), It is thought that it was possible to apply the antistatic agent uniformly by suppressing unevenness in density.

By the corona discharge treatment,

a) The surface is roughened,

b) A hydrophilic functional group such as a radical is formed on the surface.

The detailed mechanism of action, which is presumed to contribute to reducing the water contact angle, is not clear.

The transparent resin constituting the light diffusing resin plate (6) is not particularly limited. For example, a propylene polymer, a styrene polymer, an acrylonitrile-butylene-styrene copolymer, Low-density polyethylene, high-density polyethylene, linear low-density polyethylene, acrylonitrile monostyrene copolymer, acrylic monoacrylonitrile monostyrene copolymer, methyl methacrylate polymer, methacrylate Mesylate Chillylstyrene copolymer, Polyacetal, Polyamide, Polyethylene terephthalate, Polystrength bonate, Polyesterolone, Polyetherolenorephone, Methinorepentene polymer, Polyarylate, Polybutylene terephthalate, Fatty Examples of such general-purpose plastics or engineering plastics, such as resin containing a ring structure-containing ethylenically unsaturated monomer unit, polyphenylene sulfide, polyphenylene oxide, and poly ether ketone. .

The propylene polymer may be a homopolypropylene obtained by polymerizing propylene alone, or may be a copolymer of propylene and a copolymerized copolymer that can be copolymerized therewith. Among them, the propylene polymer is preferably a polymer containing 50% by mass or more of propylene units. Furthermore, it is particularly preferable that the content of propylene units in the propylene polymer is 98% by mass or more in that sufficient rigidity is obtained. The copolymer component is not particularly limited, and examples thereof include α-olefins such as ethylene and 1-butene.

The styrene polymer has 50% by mass or more, preferably 70% by mass or more of styrene units as its structural unit, and a part of the styrene polymer as long as it has 50% by mass or more of styrene units. It may be a copolymer substituted with a monofunctional unsaturated monomer unit copolymerizable with styrene.

Examples of the monofunctional unsaturated monomer copolymerizable with styrene include, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and methacrylic acid. Methacrylates such as benzyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyhexyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate , Acrylates such as phenyl acrylate, benzyl acrylate, 2-ethyl hexyl acrylate, acrylate 2-hydroxyhexyl, etc .; unsaturated acids such as methacrylic acid and acrylic acid; α —Methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenol maleimide Kishinoremare Lee Mi-de, and the like to the consequent opening. The copolymer may further contain a dartal anhydride unit and a dartal imide unit. In addition to the aforementioned polymers and copolymers, rubber As the polymer, a blend of gen-based rubber, acryl-based rubber or the like may be used.

The light diffusing resin plate (6) is a resin plate having a light diffusing function. For example, the light diffusing function is given by adding a light diffusing agent. It is not limited to what is given.

The light diffusing agent is a particle (powder that is incompatible with the transparent resin, has a refractive index different from that of the transparent resin, and has a function of diffusing transmitted light that passes through the light diffusing plate. If it contains), it will not specifically limit. For example, it may be inorganic particles such as glass particles, glass fibers, silica particles, aluminum hydroxide particles, calcium carbonate particles, barium sulfate particles, titanium oxide particles, talc, styrene polymer particles, acrylics. Organic particles such as polymer particles and siloxane polymer particles may be used. The light diffusing agent usually has a volume average particle diameter in the range of 0.5 to 40 / m. Used. The volume average particle size (D _5fl ) is determined by measuring the particle size and volume of all particles, adding up the volumes in order from the smallest particle size, and the accumulated volume is 5% of the total volume of all particles. This is the particle size of the particles at 0%.

The ratio in which the light diffusing agent is dispersed in the transparent resin is preferably in the range of 0.1 to 20 parts by mass of the light diffusing agent with respect to 100 parts by mass of the transparent resin. When the amount is 0.1 parts by mass or more, sufficient light diffusion performance can be secured, and when the amount is 20 parts by mass or less, the impact resistance of the plate itself can be prevented from being lowered.

Next, an embodiment of the light diffusing plate (1) according to the present invention is shown in FIG. In this light diffusion plate (1), a coating layer (3) containing an antistatic agent is laminated on the corona discharge treated surface (6a) of the light diffusion substrate (2). In the present embodiment, the coating layer (3) is formed by applying a solution containing an antistatic agent to the corona discharge treated surface (6a) of the light diffusion substrate (2) and drying it. It is a thing.

According to the light diffusing plate (1) having the above configuration, since the coating layer (3) containing the antistatic agent is laminated on the corona discharge treatment surface (6 a) of the light diffusing substrate (2), it is uniform. An anti-static coating layer is formed, so this light diffusing plate (1) Adhesion of dust or the like can be sufficiently prevented over the entire surface.

The antistatic agent is not particularly limited, and examples thereof include a cationic antistatic agent, an anionic antistatic agent, and a nonionic antistatic agent. The cationic antistatic agent is not particularly limited, and examples thereof include lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, lauryljetanolamine, and stearylamine hydrochloride. It is done. The anionic antistatic agent is not particularly limited, and examples thereof include alkylphosphoric acid diethanolamine, potassium alkylphosphoric acid, and alkylbenzenesulfonic acid salts. The nonionic antistatic agent is not particularly limited. For example, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyethylene glycol monolate, polyoxyethylene sorbitan monooleate, etc. Is mentioned.

The antistatic agent-containing solution for forming the coating layer (3) is not particularly limited, and examples thereof include an antistatic agent-containing aqueous solution and an antistatic agent-containing organic solution. Examples of the organic solvent used in the organic solution include alcohols such as ethyl alcohol. Among these, it is preferable to apply the antistatic agent-containing aqueous solution to form the coating layer (3) from the viewpoint of occupational hygiene and environmental preservation.

The method for forming the coating layer (3) is not particularly limited, but is preferably formed by applying the antistatic agent-containing solution. The coating method is not particularly limited, and examples thereof include a roll coater method, a rip coat method, and a knife coater method.

The concentration of the antistatic agent in the antistatic agent-containing solution is preferably set to 0.01 to 10% by mass. Further, the adhesion amount of the antistatic agent (solid content adhesion amount on one side) in the coating layer (3) is preferably set to 0.01 to 5 gZm ² , and the particularly preferable range is 0.05 to 2 g / m ² .

In the above embodiment (FIG. 2), the light diffusing plate (1) has a configuration in which the coating layer (3) is provided only on one side of the light diffusing substrate (2). The corona discharge treatment surfaces (6a) (6a) on both sides of the light diffusion substrate (2) A configuration provided with a single layer (3) and (3) may be adopted.

FIG. 3 shows an embodiment of a liquid crystal display device (30) configured using the light diffusing plate (1). In FIG. 3, (3 5) is a liquid crystal cell, (3 6) and (3 7) are polarizing plates, and (3 1) is a direct type backlight. Polarizers (3 6) and (3 7) are respectively arranged on the upper and lower sides of the liquid crystal cell (3 5), and a liquid crystal panel (transmission type image) is formed by these constituent members (3 5) (3 6) (3 7). (Display section) (3 8) is configured.

The backlight (3 1) is disposed on the lower surface side (rear surface side) of the lower polarizing plate (37). The backlight (3 1) has a rectangular box shape in plan view and a substantially box-shaped lamp box (3 4) whose upper surface (front side) is open, and the lamp box (34) spaced apart from each other. A plurality of arranged light sources (3 2), a light diffusing plate (1) arranged on the upper side (front side) of the plurality of light sources (3 2), and an upper side of the light diffusing plate (1) ( It has an optical film (33) arranged on the front side through an air layer (50) (see Fig. 3). The light diffusing plate (1) is arranged in a state in which a ventilation gap (40) is formed between the light diffusing plate (1) and the lamp box (34) at a position near the upper side of the lamp box (34). In addition, a light reflecting layer is provided on the inner surface of the lamp box (34). Further, although not shown, a blower fan is provided for discharging the air in the lamp box (34) to the outside.

In the liquid crystal display device (30) according to the above configuration, the high temperature air inside the lamp box (34) is sent out through the ventilation gap (40) by blowing air from the blower fan. Heat generated in the backlight (3 1) can be discharged efficiently. At this time, dust inside the lamp box (3 4) is also replaced by the air inside the lamp box (3 4). Since the light diffusion plate (1) has a coating layer (3) containing an antistatic agent on its surface (surface on the lamp box side), the surface of the light diffusion plate (1) (on the lamp box side) It is possible to prevent dust and the like from adhering to the entire surface, and the liquid crystal display device (30) can display high-quality and high-quality images over a long period of time.

The light source (32) is not particularly limited, and examples thereof include a fluorescent tube, a halogen lamp, a tungsten lamp, and a light emitting diode. The light diffusing substrate (2), the light diffusing plate (1), the direct type backlight (31), and the liquid crystal display device (30) according to the present invention are not particularly limited to those of the above embodiment, Any design changes within the scope of the claims are permitted without departing from the spirit thereof. Example

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

(Manufacture of surface layer forming materials)

Styrene one Metaku acrylic acid methyl copolymer (manufactured by Nippon Steel Chemical Co., Ltd. "Estylene MS 2 O ONT" styrene unit 80 mass ^_0/0, Metaku acrylic acid methyl units 20 wt%, M FR 1. 3~: I . 9 gZl O) 75.8 parts by mass, cross-linked acrylic polymer particles (light diffusing agent, “SUMIPEX XC 1 A” manufactured by Sumitomo Chemical Co., Ltd., volume average particle size 30 / zm) 23.0 parts by mass, UV absorption Agent (AD EKA "LA 3 1") 1.0 parts by mass and processing stabilizer (Sumitomo Chemical "Smizer 1 GP") 0.2 After driving 2 parts by mass, screw diameter 6 5 It is put into a twin screw extruder of mm, kneaded while being heated and melted at 200 to 260 ° C, extruded into a strand shape, and cut into pellets to form a pellet surface layer. Obtained material.

(Manufacture of light diffusing agent masterbatch for base layer)

Styrene polymer (Toyostyrene HRM40 manufactured by Toyo Styrene Co., Ltd., refractive index 1.59, MFR 0.9-9: 1.3 g, 10 minutes) 52 parts by mass, crosslinked acrylic polymer particles (light diffusion) Agent, Sumitomo Chemical "Sumipex XC 1 A") 40 parts by mass, silicone rubber particles (light diffusing agent, Toray Fill DY 33 — 7 1 9, Toray Dow Corning, volume average particle size 2 zm) 4 parts by weight, UV absorber (Sumitomo Chemical "Sumisorb 200") 2 parts by weight and processing stabilizer (Sumitomo Chemical "Sumilyzer 1 GP") It is put into a 65mm twin screw extruder, kneaded while being heated and melted at 80 to 250 ° C, extruded into a strand shape, and cut into pellets to produce a pellet-shaped light diffusing agent master batch. Gain It was.

(Manufacture of light diffusing resin plate)

Styrene polymer ("Toyostyrene HRM40" manufactured by Toyo Styrene Co., Ltd., refractive index 1.59) 95.0 parts by mass, base layer obtained by driving 5.0 parts by mass of the above light diffusing agent master batch The forming material is supplied to a main extruder with a screw diameter of 40 mm, where it is heated and melted at 20 to 25 ° C. to a multi-hold die (2 types, 3 layers distribution type). At the same time, the material for forming the surface layer is supplied to an auxiliary extruder having a screw diameter of 2 O mm, where it is heated and melted at 190 to 250 ° C. to obtain a multi-manifold die (type 2 3 Layer distribution type). These are coextruded at a die temperature of 2550 to 2600 ° C, so that a surface layer with a thickness of 0.05 mm is formed on both sides of the base layer (2 1) with a thickness of 1.4 mm. (2 2) A light diffusing resin board (6) (thickness 1.5 mm, width 2 2 Omm) with a three-layer structure in which (2 2) was laminated was obtained (see Fig. 1).

(Corona discharge treatment)

By performing corona discharge treatment using a corona discharge treatment apparatus equipped with a high-frequency power source (CT 0 2 1 2 type) manufactured by Kasuga Electric Co., Ltd. on one side of the light diffusing resin plate (6), one side is corona discharge. A light diffusing substrate (2), which is the treated surface (6a), was obtained (see Fig. 1). The line speed of this corona discharge treatment was set to 10 m. The applied power during the corona discharge treatment was set to 2820 W.

A light diffusion substrate was obtained in the same manner as in Example 1 except that the applied power during the corona discharge treatment was set to 500 W.

<Example 3>.

A light diffusing substrate was obtained in the same manner as in Example 1 except that the applied power in the corona discharge treatment was set to 7500 W.

A light diffusing substrate was obtained in the same manner as in Example 1 except that the corona discharge treatment was omitted (not performed).

Styrene polymer (Toyostyrene HRM4 0 manufactured by Toyo Styrene Co., Ltd.) 1 0 0 parts by mass and crosslinked acrylic polymer particles (light diffusing agent, “MB X 2 H” manufactured by Sekisui Plastics Co., Ltd., volume average particle size 3 / zm) After dry blending 6 parts by mass, the screw diameter is 4 A single-layer light-diffusing resin plate (thickness 1.5 mm, width 2 2 O mm) was supplied to an Omm extruder and heated and extruded at 20 to 2500 ° C. Obtained.

By performing corona discharge treatment on both surfaces of the light diffusing resin plate (6) in the same manner as in Example 1, a light diffusing substrate whose both surfaces are corona discharge treated surfaces (6a) (6a)

(2) was obtained (see Fig. 4). The conditions for the corona discharge treatment were a line speed of 10 mZ and an applied power of 2800 W.

A light diffusion substrate was obtained in the same manner as in Example 4 except that the applied power during the corona discharge treatment was set to 500 W.

A light diffusion substrate was obtained in the same manner as in Example 4 except that the applied power during the corona discharge treatment was set to 7500 W.

A light diffusing substrate was obtained in the same manner as in Example 4 except that the corona discharge treatment was omitted (not performed).

Example 7>

Propylene polymer (“Noniprene D 10 1” manufactured by Sumitomo Chemical Co., Ltd., with a propylene unit content of 99% by mass or more and an ethylene unit content of 1% by mass or less) 10 0. (ADEKA “NA 1 1”) 0.05 parts by mass were dry blended, then fed to an extruder with a screw diameter of 40 mm, and heated and melted at 20 ° C to 2500 ° C. As a result, a single-layer light-diffusing resin plate (thickness 1.5 mm, width 2 2 O mm) was obtained.

(2) was obtained (see Fig. 4). The conditions of the corona discharge treatment were a line speed of 10 mZ and an applied power of 2800 W.

Three A light diffusing substrate was obtained in the same manner as in Example 7 except that the applied power during the corona discharge treatment was set to 50 OW.

Example 9>

A light diffusion substrate was obtained in the same manner as in Example 7 except that the applied power during the corona discharge treatment was set to 7500 W.

A light diffusing substrate was obtained in the same manner as in Example 7 except that the corona discharge treatment was omitted (not performed).

Propylene polymer (“Nobrene D 1 0 1” manufactured by Sumitomo Chemical Co., Ltd.) 1 0.0.0 parts by mass, silicone rubber particles (light diffusing agent, “Trefill DY 3 3-7 1 9” manufactured by Toray Dow Coung Co., Ltd.) 1 2 parts by mass and nucleating agent (“NA 1 1” manufactured by AD EKA) 0. After driving 5 parts by mass, supply to an extruder with a screw diameter of 4 Omm. A single-layer light-diffusing resin plate (thickness 1.5 mm, width 2 2 Omm) was obtained by heat-melt extrusion at 50 ° C.

(2) was obtained (see Fig. 4). The conditions for the corona discharge treatment were an in-speed of 10 mZ and an applied power of 2880 W.

A light diffusing substrate was obtained in the same manner as in Example 10 except that the applied power during the corona discharge treatment was set to 500 W. .

A light diffusion substrate was obtained in the same manner as in Example 10 except that the applied power during the corona discharge treatment was set to 7500 W.

A light diffusing substrate was obtained in the same manner as in Example 10 except that the corona discharge treatment was omitted (it was not performed).

Four

± ^ s

Measurement and applicability were evaluated. These evaluation results are shown in Tables 1-4.

Water contact angle measurement method>

The contact angle of pure water (distilled water) with respect to the corona discharge treated surface of the light diffusion substrate was measured according to JISK 6 7 6 8-1 9 9 9. That is, using a contact angle meter “CA-X” manufactured by Kyowa Interface Science Co., Ltd., the contact angle of pure water to the corona discharge treated surface of the light diffusion substrate was measured by the 0 Z2 method. ,

Applicability Evaluation Method>

Each light diffusing substrate was cut into a size of 5 O mm x 5 O mm, and an antistatic agent aqueous solution (quaternary ammonia-sulfuric acid-based antistatic agent made by Nippon Pure Chemical Co., Ltd.) was applied to the corona discharge-treated surface of these light diffusing substrates. An aqueous solution of “SAT_ 6 C” diluted 100 times with water was dropped about 1 milliliter, and then spread evenly using a small roll coater. Thereafter, it was naturally dried to obtain an antistatic light diffusion plate. The applicability was visually evaluated based on the following criteria.

(Criteria)

“◎”: Uniform coating was possible over the entire corona discharge treatment surface.

Γ ○ ”… can be applied almost uniformly over the entire surface of the corona discharge treatment surface Γχ”… cannot be applied uniformly over the entire surface of the corona discharge treatment surface (partially of the application of the antistatic agent) The shading unevenness was remarkable).

Next, each light diffusion plate obtained as described above was evaluated according to the following evaluation method.

These evaluation results are shown in Tables 1-4.

In accordance with JISK 6 9 1 1-1 9 9 5, insulation meter (manufactured by TOA DK Corporation, SM-8 2 2 0) and electrode for flat plate samples (manufactured by TOA DK Corporation, S ME- 8 3 1 1) was used to measure the surface resistivity (Ω well) of the light diffusing plate. Before the measurement, the measurement sample was left for 6 hours under conditions of 23 ° CX humidity 50% RH for condition adjustment.

> Total light transmittance measurement method>

Total light transmittance of light diffuser according to JISK 7 3 6 1— 1 9 9 7 T t (%) Was measured.

The diffused light transmittance T d (%) of the light diffusing plate was measured according to JISK 7 1 3 6— 2 0 0 0.

Glow value measurement method>

The haze value (%) of the light diffusing plate was measured according to JISK 7 1 3 6—2 0 0 0. Measurement of yellowness Y I, chromaticity x, chromaticity y by spectral transmittance measurement>

Using a self-recording spectrophotometer equipped with an integrating sphere ("UV-400" manufactured by Hitachi, Ltd.), the spectral transmittance of the light diffuser plate in the wavelength range of 3800 to 780 nm was measured. Based on this, yellowness YI, chromaticity x, and chromaticity y were calculated.

As is clear from Tables 1 and 2, the light diffusion substrates of Examples 1 to 6 according to the present invention have a water contact angle of 60 ° or less on the corona discharge treatment surface, and are not subjected to corona discharge treatment. Compared with the light diffusing substrates of Examples 1 and 2, the coating properties are improved. In the light diffusing substrates of Examples 1 to 6, the antistatic agent could be uniformly applied over the entire corona discharge treatment surface.

As is apparent from Tables 3 and 4, the light diffusion substrates of Examples 7 to 12 according to the present invention have a water contact angle of 90 ° or less on the corona discharge treatment surface and are not subjected to corona discharge treatment. Compared with the light diffusion substrates of Comparative Examples 3 and 4, the applicability is significantly improved. In the light diffusing substrates of Examples 7 to 12, the antistatic agent could be uniformly applied over the entire corona discharge treated surface.

In Examples 7 to 9 and Comparative Example 3, although the light diffusing agent is not included, the propylene resin is a crystalline resin, and there are crystal parts and amorphous parts. It looks slightly cloudy, and a slight light diffusion performance can be obtained without adding a light diffusing agent. Industrial applicability

The light diffusing substrate of the present invention is suitably used for the production of a light diffusing plate for a direct type backlight, but is not particularly limited to such applications. Further, the antistatic light diffusing plate of the present invention is preferably used as a component in a direct type backlight. In particular, it is not limited to such an application. Further, the direct type backlight according to the present invention is suitably used for a liquid crystal display device, but is not particularly limited to such an application.

2

Claims

Scope of request

[Claim 1]

A light diffusing substrate on which at least one surface of a light diffusing resin plate containing a transparent resin is subjected to corona discharge treatment.

[Claim 2]

2. The light diffusing substrate according to claim 1, wherein the transparent resin is a propylene polymer or a styrene polymer.

[Claim 3]

A light diffusing substrate in which a resin containing a propylene polymer forms at least one surface and a water contact angle on the surface is 90 ° or less.

[Claim 4]

A light diffusing substrate in which a resin containing a styrene polymer forms at least one surface, and the water contact angle of the surface is 60 ° or less.

[Claim 5]

2. A light diffusing plate, wherein a coating layer containing an antistatic agent is laminated on the corona discharge treated surface of the light diffusing substrate according to claim 1.

[Claim 6]

4. A light diffusing plate, wherein a coating layer containing an antistatic agent is laminated on a surface of the light diffusing substrate according to claim 3 having a water contact surface of 90 ° or less.

[Claim 7]

5. A light diffusing plate, wherein a coating layer containing an antistatic agent is laminated on a surface of the light diffusing substrate according to claim 4 having a water contact surface of 60 ° or less.

[Claim 8]

6. The light diffusing plate according to claim 5, wherein the coating layer is formed by applying a solution containing an antistatic agent to a light diffusing substrate and drying the solution.

[Claim 9]

7. The light diffusing plate according to claim 6, wherein the coating layer is formed by applying a solution containing an antistatic agent to a light diffusing substrate and drying the solution. [Claim 1 0]

8. The light diffusing plate according to claim 7, wherein the coating layer is formed by applying a solution containing an antistatic agent to a light diffusing substrate and drying it.

[Claim 1 1]

Use of the light diffusing plate according to any one of claims 5 to 10 as a part in a direct type backlight.

[Claim 1 2]

A direct type backlight comprising: the light diffusing plate according to any one of claims 5 to 10; and a plurality of light sources disposed on a back side of the light diffusing plate.

[Claim 1 3]

A light diffusing plate according to any one of claims 5 to 10, a plurality of light sources arranged on the back side of the light diffusing plate, and a liquid crystal panel arranged on the front side of the light diffusing plate. LCD LCD device.