JP2001154006A - Antidazzle layer and optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop an antidazzle layer and an optical member using the layer, which can prevent induction of glare due to a reduced size of pixels and which effectively prevents hindrance against visibility by the surface reflection of external light, even in a display device having a large-size screen. SOLUTION: This antidazzle layer has a fine rugged structure on the surface with <=40 μm average crest-to-trough pitch and >=5 deg. average inclination angle, and the optical member has this antidazzle layer on at least one surface of a polarizing plate or elliptically polarizing plate. Therefore, various kinds of display devices, such as a liquid crystal display device having excellent display quality such as visibility, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiglare layer suitable for preventing visual disturbance due to surface reflection of external light in various display devices.

[0002]

2. Description of the Related Art Conventionally, in various display devices such as a liquid crystal display device, a CRT, and a plasma display, a screen provided on a surface of a screen or the like for the purpose of preventing image disturbance due to reflection of external light of a fluorescent lamp. As the glare layer, those provided with various fine uneven structure surfaces so as to scatter and reflect external light have been known. However, with the recent increase in the size of the screen, the conventional anti-glare layer has a problem that the scattering effect is insufficient and the reflection of external light cannot be sufficiently prevented.

[0003] Enhancement of the anti-glare effect by enhancing the scattering effect has been studied. However, in this case, with the recent reduction in pixel size due to the high definition of images, point-like luminance unevenness randomly appears on the screen, probably because light interferes with pixels and fine irregularities, and the image is coarse. There is a problem that induces a glare phenomenon that is difficult to see.

[0004]

SUMMARY OF THE INVENTION The present invention effectively prevents the occurrence of glare due to the reduction in pixel size, and effectively prevents the occurrence of visual disturbance due to surface reflection of external light even in a display device having a large screen. It is an object of the present invention to develop an anti-glare layer and an optical member using the same.

[0005]

According to the present invention, an average peak-to-valley spacing of 40 is provided on a surface.
μm or less, and an antiglare layer having a fine uneven structure with an average inclination angle of 5 ° or more, and an optical member having the antiglare layer on at least one side of a polarizing plate or an elliptically polarizing plate Is provided.

[0006]

According to the present invention, the use of the anti-glare layer having the fine uneven structure having the above-mentioned shape characteristics prevents the occurrence of glare even in a large-screen display device having a small pixel size. It is possible to effectively prevent the occurrence of visual disturbance due to surface reflection of light, and to apply an optical member using the same to obtain various display devices such as a liquid crystal display device having excellent display quality such as visibility.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The antiglare layer according to the present invention has a fine uneven structure with an average peak-to-valley interval of 40 μm or less and an average inclination angle of 5 ° or more on the surface. The shape of the fine concavo-convex structure can be measured by a stylus-type surface roughness measuring instrument or the like. Scanning is performed in a fixed direction with a length of 3 mm, and a change in the vertical movement of the measuring needle in that case is measured, which can be known as a recorded surface roughness curve.

The average peak-to-valley interval is assumed to be a reference line on which the unevenness change of the surface roughness curve can be evaluated as a convex portion based on a portion where the unevenness change in the surface roughness curve is minute (a portion almost flat). With the average of the heights of the projections from the reference line as the center line, the average of the distance between the intersections based on the intersection when the surface roughness curve passes the center line from bottom to top (or from top to bottom) Can be defined as The average inclination angle can be defined as the average of the absolute value of the gradient based on the gradient of the portion of the surface roughness curve where the above-mentioned unevenness change is minute.

The fine unevenness structure of the antiglare layer according to the present invention has an average peak-to-valley interval of 40 μm or less and an average inclination angle of 5 ° or more.
The average peak-to-valley interval is 5 to 30 μm, especially 10 to 25 μm, and the average inclination angle is 6 degrees or more from the point of preventing the occurrence of glare phenomenon due to the enlargement of the screen and preventing the occurrence of visual disturbance due to surface reflection of external light, In particular, it is preferable to have a fine uneven structure of 7 degrees or more. The upper limit of the average inclination angle is not particularly limited, but is generally 30 degrees or less, especially 20 degrees or less.

The method of forming the above-mentioned fine uneven structure surface is not particularly limited, and it can be formed by applying an appropriate method according to the related art. Incidentally, examples thereof include a sandblasting method, an embossing method, a roughening method such as an etching method, and a resin coating method containing transparent particles.

The transparent particles may be conductive, for example, made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, or the like having an average particle size of 0.5 to 20 μm. One or more kinds of inorganic particles, organic particles composed of a crosslinked or uncrosslinked polymer or the like are used. The amount of the transparent particles used is 2 to 100 parts by weight per 100 parts by weight of the transparent resin,
In particular, 5 to 80 parts by weight, especially 10 to 60 parts by weight, is generally used.

As the transparent resin for forming the coating film by blending the transparent particles, any suitable resin may be used, and among them, acrylic resin, urethane resin, acrylic urethane resin, epoxy resin, silicone resin, etc. A resin that is cured by heat, ultraviolet light, or the like is preferably used. Such a curable resin is also effective for a hard coat treatment for the purpose of preventing the antiglare layer from being damaged.

The antiglare layer is provided directly on a display device to which the display device is applied, a method for directly providing the display device on a member such as a polarizing plate or an elliptically polarizing plate, or a fine uneven structure is provided on the surface of a transparent film substrate. One or two or more layers can be provided at appropriate places on the surface of the display device by an appropriate method such as a method of directly providing the anti-glare sheet on the display device or a member forming the display device.

In the above, as the transparent film substrate for supporting the antiglare layer, one composed of one or more suitable transparent polymers can be used, and the polymer to be formed is not particularly limited. Above all, transparency and mechanical strength,
Those made of a polymer having excellent thermal stability and water resistance are preferred.

Examples of the polymers include acetate resins, carbonate resins, arylate resins and sulfone resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone resins and polyamide resins, and polyimide resins. Olefin resins such as styrene resins, styrene resins and cyclic polyolefins, and acrylic resins.

The thickness of the transparent film substrate can be appropriately determined according to the strength and light transmittance. Generally 500 μm or less, especially 10-30
The thickness is 0 μm, especially 15 to 200 μm. The surface of the transparent film substrate may be subjected to an appropriate treatment such as a corona treatment, an ultraviolet irradiation treatment, a plasma treatment, a sputter etching treatment, an undercoat treatment, etc. for the purpose of improving the adhesion of a layer attached thereto. .

On the other hand, as a polarizing plate or an elliptically polarizing plate to which the above-mentioned antiglare layer is provided as an antiglare sheet as required, a polarizing film or a polarizing film protected by a transparent protective layer,
An appropriate device used for forming a liquid crystal display device or the like, such as a laminate of a retardation plate and the like, can be used, and the type thereof is not particularly limited.

Incidentally, as a specific example of the polarizing film, iodine and / or diamine is added to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. Examples thereof include stretched films obtained by adsorbing a chromatic dye, and oriented polyene films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride.

The transparent protective layer optionally provided on one or both sides of the polarizing film may be made of an appropriate material such as a transparent resin for blending transparent particles or a polymer for forming a transparent film substrate as exemplified by the above-mentioned antiglare layer. Can be formed by a suitable method such as a coating method or a lamination method of a film. Further, a fine uneven structure may be provided on the surface of the transparent protective layer to serve also as an anti-glare layer, and the formation thereof may be in accordance with the above-described method of forming the anti-glare layer.

Examples of a retardation plate for obtaining an elliptically polarizing plate by laminating with a polarizing plate include suitable polymers such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate and polyamide. A birefringent film obtained by stretching a film made of, a liquid crystal polymer having been subjected to an alignment treatment, and an alignment layer thereof supported by a transparent film substrate. The retardation plate may be one in which two or more kinds of retardation films or the like are laminated to control optical characteristics such as retardation.

The antiglare layer may be provided on one or both sides of the transparent film substrate, the polarizing plate, or the elliptically polarizing plate as described above, and one or more layers may be provided at appropriate positions on the display device. When applied to a device, the device may be applied with a suitable optical layer such as an anti-reflection layer. The same applies to the case where an anti-glare layer is provided on an appropriate member to form an optical member.

The anti-reflection layer is provided for the purpose of suppressing surface reflection of external light. For example, the anti-reflection layer may be formed of a multilayer coating film of an inorganic oxide having a different refractive index or a coating film of a low refractive material such as a fluorine compound. It can be formed on the antiglare layer as an interference film or the like. In addition, for example, when an anti-reflection layer reflecting a fine uneven structure on the lower surface is formed by an appropriate coating method such as a vacuum evaporation method, an ion plating method, a sputtering method, a plating method or a sol-gel method, an antiglare layer. Can also be used.

Further, the antiglare layer and the optical member may be provided with a transparent conductive layer for the purpose of preventing static charge and shielding electromagnetic waves. As the transparent conductive layer, one layer or two or more layers can be provided at appropriate locations inside or on the surface of the layer forming the transparent film substrate or the optical member. The formation of the transparent conductive layer includes, for example, a coating method of a transparent conductive paint, a vacuum deposition method and a sputtering method of a conductive material, an ion plating method and a chemical vapor deposition method, a spray pyrolysis method and a chemical plating method, an electroplating method and the like. It can be performed by an appropriate method such as a combined method.

The conductive materials include, for example, indium oxide, tin oxide, indium / tin mixed oxide, cadmium oxide, titanium oxide, indium, tin, gold, silver, platinum, and the like.
Appropriate materials such as palladium and copper, aluminum and nickel, chromium and titanium, iron and cobalt, copper iodide and their alloys can be used alone or in combination of two or more, and there is no particular limitation, and any of known materials is used. sell.

Further, on the surface of the anti-glare layer and the optical member,
A fluorine-based surface treatment coat can be provided for the purpose of making it difficult to attach fingerprints and other stains, and to make it easier to wipe off the attached stains. In forming the coat, an appropriate fluorine-based compound that can form a film having a small surface energy, such as a fluorine-based resin or a fluorine-based silane coupling agent, can be used.

In addition, an adhesive layer may be provided on one or both surfaces of the anti-glare sheet or optical member, especially on the surface having no anti-glare layer, for the purpose of bonding to other members. For forming the pressure-sensitive adhesive layer, a pressure-sensitive adhesive having a base polymer of an appropriate polymer such as an acrylic polymer, a silicone-based polymer, polyester, polyurethane, polyether, or synthetic rubber can be used, and is not particularly limited. Among them, those having excellent optical transparency such as acrylic pressure-sensitive adhesives and exhibiting adhesive properties such as appropriate wettability, cohesiveness and adhesiveness are preferable, and those having excellent weather resistance and heat resistance in addition to the above are particularly preferable. preferable.

Incidentally, examples of the acrylic pressure-sensitive adhesive include an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, a butyl group and an ethylhexyl group (meth).
Acrylic polymer using one or more alkyl ester of acrylic acid as a main component, and one of appropriate monomer components other than acrylic acid alkyl ester for the purpose of improving adhesive properties as required. Examples of the base polymer include those obtained by copolymerizing a kind or two or more kinds.

The adhesive layer may be attached to the transparent film substrate or the optical member, for example, by directly applying the adhesive liquid on the transparent film substrate or the like by an appropriate developing method such as a casting method or a coating method. Alternatively, it can be performed by an appropriate method such as a method of forming an adhesive layer on a separator and transferring it onto a transparent film substrate or the like according to the above. The thickness of the adhesive layer can be appropriately determined according to the adhesive force and the like, and is generally 1 to 500 μm.
It is said.

If necessary, the adhesive layer may contain, for example, natural or synthetic resins, especially, tackifying resins, fillers, pigments, colorants, and antioxidants. Alternatively, a transparent particle may be blended to form an adhesive layer exhibiting light diffusion. Further, the adhesive layer can be provided as a superimposed layer of different compositions or types. When the adhesive layer is exposed on the surface, it is preferable to cover and protect the surface with a separator or the like until practical use.

The antiglare layer, the transparent film substrate, and the optical member are treated with an ultraviolet absorber such as a salicylate compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound. Depending on the method, it is possible to provide ultraviolet absorbing ability. The antiglare layer and the optical member according to the present invention can be applied to various display devices such as a liquid crystal display device, a CRT, and a plasma display.

[0031]

EXAMPLES Example 1 30 parts of spherical resin fine particles having an average particle diameter of 2.5 μm (parts by weight,
The same shall apply hereinafter), UV-curable acrylic urethane resin 10
0 parts and 5 parts of a photopolymerization initiator are mixed with a solvent by a homogenizer to prepare a homogeneous dispersion having a volatile concentration of 60%.
It was applied on one side of a triacetyl cellulose film having a thickness of 80 μm with a bar coater, dried, and then cured with ultraviolet rays to obtain an anti-glare sheet having a thickness of 1 μm and having an anti-glare layer having a fine irregular surface structure.

Comparative Example 1 Example 1 was repeated except that the amount of the spherical resin fine particles was changed to 3 parts.
An anti-glare sheet was obtained by forming an anti-glare layer according to the following.

Comparative Example 2 An antiglare sheet was obtained by forming an antiglare layer in the same manner as in Example 1 except that the amount of the spherical resin fine particles was changed to 10 parts.

Evaluation test Average peak-to-valley interval, average inclination angle The surface of the anti-glare layer in the anti-glare sheet obtained in each of the examples and comparative examples was a measuring needle having a diameter of 1 mm and a conical tip having a vertex angle of 55 ° made of diamond. Using a stylus type surface roughness measuring device having a scanning speed of 0.3 mm / sec and a cut-off value of 0.8 mm, measure in a fixed direction at a length of 3 mm, and determine the average peak-to-valley interval from the surface roughness curve. The average tilt angle was determined.

Anti-glare properties The anti-glare sheets obtained in Examples and Comparative Examples have a pixel size of 170
The anti-glare layer is adhered to the screen of a liquid crystal display device (15 "UXGA) with a size of 15 nm × 170 nm and a screen size of 15 inches, and a fluorescent lamp is reflected on the screen with the device turned off. The outline of the shadow of the fluorescent lamp was observed with a naked eye, and the evaluation was performed on a five-point scale, with five cases where the outline was not visible at all and one case where the outline was clearly visible.

Brightness Variation (Glittering) The liquid crystal display device according to the above-described antiglare test was turned on to set the brightness to a white state with the maximum brightness. In this case, the center of the screen was photographed with a CCD camera in an area of 20 mm square. Then, the distribution of the bright spots was calculated, and the variation in luminance due to the luminance unevenness was examined.

The results are shown in the following table. Average peak-to-valley interval (μm) Average tilt angle (degree) Anti-glare property Variation in luminance Example 1 18.6 7.45 5 1.00 Comparative example 1 139.0 3.09 2 1.04 Comparative example 2 49.3 4 .39 3 1.03

From the table, it can be seen that the embodiment shows excellent anti-glare properties even when the pixel size is small and the screen is large, so that the reflection of the fluorescent lamp is hardly seen, the variation in luminance on the screen is small, and the glare phenomenon is also small. It can be seen that it is prevented. However, in the comparative example 1, the reflection of the fluorescent lamp was clearly seen, the visibility was significantly disturbed, and the variation in luminance on the screen was large. It turns out that it is big.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Masami Masada 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 2H042 BA02 BA03 BA13 BA15 BA20 2H049 BA02 BA04 BB62 BC22 2H091 FA08X FA08Z FA11X FA37X FB02 FB04 FB06 FC02 FC12 FC23 FD06 FD15 GA16 LA03 LA16

Claims (3)

[Claims] 1. An anti-glare layer having a fine uneven structure having an average peak-to-valley interval of 40 μm or less and an average inclination angle of 5 ° or more on the surface. 2. The antiglare layer according to claim 1, which is supported by a transparent film substrate. 3. An optical member comprising the antiglare layer according to claim 1 on at least one side of a polarizing plate or an elliptically polarizing plate.