JP2012168244A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device that has excellent expression of black, and a suppressed rainbow diffraction pattern.SOLUTION: An image display device comprises: an image display part (10); and a light-transmissive protection part (12) arranged on the image display part. There is an interface (s) having refractive index difference Δn of 0.01 to 0.2 between the image display part and the protection part. Standard deviation σ of in-plane distribution of optical path lengths between the image display part and the protection part is 40 nm or more.

Description

  The present invention relates to an image display device, and more particularly to an image display device that is excellent in blackening in a bright room environment and that reduces the occurrence of iridescent diffraction patterns that appear in reflected light.

For the purpose of improving aesthetics and the like, an image display device has been proposed in which a translucent protective portion is disposed on an upper portion of an image display portion such as a liquid crystal display panel. In an image display device having this configuration, a gap is generally present between the image display unit and the protection unit. However, the presence of this gap causes light reflection at the refractive index interface, resulting in a decrease in contrast. Then there is a problem. In order to solve this problem, it has been proposed to fill the voids with a cured resin (for example, Patent Document 1).
However, when the gap between the image display unit and the protection unit is uniformly filled with the cured resin, a rainbow-colored diffraction pattern is recognized on the display surface, and visibility may be reduced. Details of the cause have not been known so far, and no solution has been proposed.

By the way, conventionally, the decrease in the visibility of the image display device is considered to be caused by the reflection of external light in a bright room environment. In order to prevent the reflection of external light, a fine uneven shape is formed on the surface. Arrangement of an antiglare film having is performed. However, when an anti-glare film is disposed, there is a problem that black tightening is deteriorated and the screen becomes whitish. In order to solve this, an antiglare film having a structure in which layers having an uneven surface with a refractive index different by 0.06 or more has been proposed (Patent Document 2).
A display surface material having an uneven surface has also been proposed in order to make an attached fingerprint inconspicuous (for example, Patent Document 3). Furthermore, with regard to a hard coat layer for an image display device including a plurality of layers having different refractive indexes, it has been proposed to form an uneven shape at the interface between the layers having different refractive indexes (for example, Patent Document 4). ~ 6).

  However, forming an uneven surface on the surface material of the image display device, as described above, causes a reduction in black tightening, and in particular, in the image display device having the above-described configuration including a protection unit that places importance on aesthetics, It is common technical knowledge that it is desirable to avoid the use of an uneven interface. In the first place, the cause of the iridescent diffraction pattern recognized in the image display device having the above-described configuration is not elucidated, and the problems described in Patent Documents 2 to 6 are also different. For example, in the technologies disclosed in Patent Documents 4 to 6, the visibility decreases due to interference unevenness caused by the lamination of layers having different refractive indexes, and a predetermined uneven shape is used as an interface. Forming and mitigating. However, the image display device having the above-described configuration having the protection unit is not based on a configuration in which layers having different refractive index differences are stacked, and the interference unevenness solved in Patent Documents 4 to 6 and the protection unit are provided. The rainbow-colored diffraction pattern of the image display apparatus having the above configuration is a phenomenon caused by a different cause. Therefore, in the background art, it can be said that there is no motivation for introducing the uneven interface in the image display device having the above-described configuration including the protection unit.

JP 2005-55641 A JP 2009-150998 A JP 2007-34027 A JP-A-8-197670 JP 2003-205563 A JP 2007-90656 A

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide an image display apparatus that has a clear feeling, good black tightening, and reduced generation of iridescent diffraction patterns. .

  As a result of various studies on the cause of the rainbow-colored diffraction pattern (hereinafter sometimes referred to as “rainbow-colored diffraction pattern”) of the image display device having the above-described configuration provided with the protection unit, the present inventor has produced a rainbow-colored diffraction pattern. It has been found that the main cause is the periodic structure inside the image display unit (for example, a periodic structure formed by arranging a plurality of pixels or electrodes having the same shape with a predetermined period). A part of the external light is incident from the translucent protection part and reflected by various members inside the image display part. It was found that if the periodic structure is inside the image display unit, the reflected light is diffracted and the diffracted light interferes with each other, so the wavelength range of the reflected light varies depending on the direction and is recognized as an iridescent diffraction pattern. . Color unevenness may also occur due to interference unevenness solved in the above Patent Documents 4 to 6, etc., but this is due to the change in the reflection spectrum due to the unevenness of the film thickness, This phenomenon is different from the iridescent diffraction pattern of the present invention. In addition, the interference unevenness described in Patent Documents 4 to 6 and the like is caused by the structure itself of the display material or the like in which a plurality of layers having different refractive indexes are stacked, whereas the rainbow diffraction pattern As described above, this is mainly due to the periodic structure existing inside the image display unit, and is different from the interference unevenness in that it appears uniformly anywhere on the screen.

  As a result of further various studies based on the above knowledge, the present inventor has an interface having a refractive index difference within a predetermined range between the protective part and the image display part of the image display device having the above structure, and It has been found that by forming the optical path length between the protection unit and the image display unit within a predetermined range in the plane, it is possible to reduce the generation of the rainbow diffraction pattern without reducing the black tightening. Based on this knowledge, further studies have been made and the present invention has been completed.

Means for solving the above problems are as follows.
[1] An image display device having an image display unit, and a translucent protection unit disposed on the image display unit,
An interface having a refractive index difference Δn of 0.01 to 0.2 exists between the image display unit and the protection unit, and an in-plane optical path length between the image display unit and the protection unit A standard deviation σ of distribution is 40 nm or more.
[2] The image display according to [1], wherein an optical film is provided between the image display unit and the protection unit, and the interface is an adjacent surface between the optical film and a layer adjacent thereto. apparatus.
[3] The image display device according to [2], wherein the surface roughness Ra of the adjacent surface of the optical film is 150 nm to 10000 nm.
[4] The image display device according to [2] or [3], wherein an average interval of unevenness of adjacent surfaces of the optical film is 10 μm to 1000 μm.
[5] The image display device according to [4], wherein the optical film contains translucent particles.
[6] The image display device according to [5], wherein the translucent particles have an average particle diameter of 5.0 to 20.0 μm.
[7] Any one of [2] to [6], wherein the optical film is a film having a laminated structure including a base film and a layer containing at least translucent particles on the base film. Image display device.
[8] The image display device according to any one of [2] to [7], wherein an adjacent surface of the optical film is sandblasted.
[9] The image display device according to any one of [2] to [8], wherein the optical film is made of or includes a film produced by a casting method.
[10] Any of [2] to [9], wherein the optical film is or includes a film produced by a casting method from a solution containing a main component polymer prepared by a solvent having a dielectric constant of 35 or more. Image display device.
[11] Any of [2] to [10], wherein the optical film is or includes a film made by a casting method using a solution containing at least particles and a main component polymer. Image display device.
[12] The optical film is composed of or includes a film produced by a co-casting method using a solution containing at least particles and a main component polymer, and a solution containing the main component polymer and no particles. The image display device according to any one of [2] to [11].
[13] The image display device according to any one of [2] to [12], wherein the optical film is a protective film for a polarizing plate.
[14] The image display device according to any one of [2] to [13], wherein the layer adjacent to the optical film is a filled layer made of a curable resin composition.

  According to the present invention, it is possible to provide an image display device that has a clear feeling, good black tightening, and reduced generation of iridescent diffraction patterns.

It is a cross-sectional schematic diagram of an example of the image display apparatus of this invention. It is a cross-sectional schematic diagram of an example of the conventional image display apparatus.

  The present invention is described in detail below. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value. Hereinafter, the present invention will be described with reference to the drawings. However, the drawings are schematic views, and the relative relationship between the thicknesses of the respective layers does not reflect the actual relationship.

  The present invention relates to an image display device having an image display unit and a translucent protection unit disposed on the image display unit. 2. Description of the Related Art Conventionally, in an image display device provided with a translucent protective part such as a glass plate or a plastic substrate on the upper part of an image display part such as a liquid crystal panel, an image display part 50 and a protective part 52 as shown in FIG. In general, a spacer 54 is disposed between and a void 56 is formed, or as shown in FIG. 2B, a curable resin composition is filled and cured to form a filled layer 56 ′. Is. That is, in the prior art, there is a gap 56 or a filling layer 56 ′ made of a uniform curable resin between the image display unit 50 and the protection unit 52, and there is no interface having a refractive index difference. Further, since the optical path length is calculated from the sum of the products of the refractive indexes of the respective layers and the thicknesses of the respective layers (details will be described later), the optical path length is protected from the image display unit 50 in which the uniform void 56 and the filled layer 56 ′ exist. The optical path length with the portion 52 is substantially constant in the plane. However, in the prior art shown in FIGS. 2A and 2B, the rainbow diffraction pattern is recognized on the screen, and the visibility may be lowered.

In the present invention, an interface having a refractive index difference Δn of 0.01 to 0.2 exists between the image display unit and the protection unit, and an optical path between the image display unit and the protection unit. By setting the standard deviation σ of the long in-plane distribution to 40 or more, the above-mentioned problems are solved while maintaining a high blackness. Here, in this specification, the optical path length is defined as a value calculated by Σni × hi, and n
i means the refractive index of the i-th layer, and hi means the thickness of the i-th layer. i means an integer of 1 or more and N or less (where N is the number of layers existing between the image display unit and the protection unit, and N is 2 or more).

  In the prior art shown in FIGS. 2 (a) and 2 (b), it has been found by the inventors that the rainbow-color diffraction pattern is generated on the screen due to the periodic structure existing inside the image display unit. It was. The term “periodic structure” as used herein refers to a structure in which members having the same shape such as electrodes, pixels, and ITO fine structures in the pixels are arranged at a predetermined period. When external light enters from the translucent protective part, a part of it reaches the image display part and is reflected by various reflecting elements inside the image display part. When the periodic structure exists in the image display, the light reflected by the periodic structure is diffracted and interferes with each other. Light reflected in one direction is intensified by interference, light reflected in the other direction is weakened by interference, and external light incident from the protection unit is not monochromatic light. This causes a phenomenon in which light in the wavelength region is intensified, and light reflected in other directions is intensified in other wavelength regions. It appears as an iridescent diffraction pattern on the image. In the present invention, the rainbow-color diffraction pattern resulting from the periodic structure existing inside the image display unit has an interface having a refractive index difference within a predetermined range between the image display unit and the protection unit. By distributing the optical path length between the display unit and the protection unit within a predetermined range in the plane, the black tightening is reduced without being reduced.

  In order to have an in-plane distribution of the optical path length, it is necessary to have an interface with different refractive index differences and an uneven surface. On the other hand, it is conventionally known that disposing the uneven surface on the upper part of the image display unit causes a reduction in black tightening. For example, when the concavo-convex structure faces air, a large amount of light is reflected because the difference in refractive index at the interface with air is large. Furthermore, since the concavo-convex structure scatters light in various directions, the entire screen becomes whitish and black tightening deteriorates. On the other hand, in the present invention, even if a surface with an uneven shape exists, the black index is not reduced by setting the difference in refractive index within a predetermined range and distributing the optical path length within a predetermined range in the surface. The fact that the iridescent diffraction pattern is reduced and the effect of the present invention is obtained with such a configuration can be said to be surprising that it cannot be predicted in view of the background art and the like.

FIG. 1 shows a schematic cross-sectional view of an example of the image display device of the present invention.
The image display device shown in FIG. 1 has an image display unit 10 made of a liquid crystal panel or the like, a translucent protection unit 12 such as a glass plate or a plastic substrate, and a refractive index difference Δn between 0.01 and 0 between 16. .2 interface s. A layer 16a and a layer 16b are disposed between the image display unit 10 and the protection unit 12, and the interface s exists between these layers 16a and 16b, that is, on their adjacent surfaces. is there.

  The adjacent surfaces of the layer 16a and the layer 16b preferably have a fine uneven shape. For example, when an optical film having a concavo-convex shape on the surface is arranged as the layer 16a, the void is filled with a curable resin composition, and the composition is cured to form a filled layer, the concavo-convex on the surface adjacent to the optical film 16a The shape can be maintained. In this embodiment, the optical film becomes the layer 16a, the filling layer becomes the layer 16b, and the interface s is an adjacent surface between the optical film and the filling layer.

In the said aspect, it is preferable that the surface roughness Ra of the optical film arrange | positioned as the layer 16a is 150 nm-10000 nm, and it is more preferable that it is 1000 nm-3000 nm. Moreover, it is preferable that it is 10 micrometers-1000 micrometers, and, as for the average space | interval Sm of the unevenness | corrugation of the said optical film, it is more preferable that they are 20 micrometers-200 micrometers. The surface roughness Ra and the average interval between the irregularities are arranged between the image display portion and the protection portion, and the image display portion is arranged adjacent to the filling layer having a refractive index difference in the range. The standard deviation of the in-plane distribution of the optical path length with respect to the protection part can be easily adjusted to about 40 nm to 1000 nm.
Ra and Sm can be measured according to JIS B 0601 (1994).

  The refractive index difference Δn of the interface s is 0.01 to 0.2, preferably 0.01 to 0.15, and more preferably 0.01 to 0.1. As long as the refractive index difference Δn is in the above range, the refractive indexes of the layers 16a and 16b are not particularly limited. However, it is not preferable to dispose a member having an excessively high refractive index from the viewpoint of suppressing deterioration in display quality due to light reflection at the interface. From this viewpoint, the refractive indexes of the layer 16a and the layer 16b are 1.35 to 35. It is preferably in the range of about 1.7, and more preferably in the range of about 1.35 to 1.55.

Standard deviation σ of in-plane distribution of the optical path length (Σni × hi) between the image display unit 10 and the protection unit 12
Is over 40. The upper limit is not particularly limited, but is preferably 1000 nm or less from the viewpoint of suppressing deterioration in display quality due to light scattering, that is, the standard deviation σ is preferably 40 nm to 1000 nm, and preferably 60 nm to 500 nm. Is more preferable, and it is further more preferable that it is 80 nm-200 nm. Here, the optical path length refers to the optical path length in the normal direction perpendicular to the layer surface. Specifically, for all layers existing between the image display unit and the protection unit, the refractive index n, the thickness It is calculated by summing the product with the length h. For example, when there are two layers, it is calculated as the sum of the product of the refractive index n and the thickness h of one interface and the product of the refractive index n and the thickness h of the other interface. Alternatively, it is calculated as the sum of the product of the refractive index n of one layer and the height h ′ from the average line and the product of −h ′ in which the sign of the refractive index n of the other layer and the height from the average line is reversed. Is done. This is because what is important for obtaining the effect of the present invention is the magnitude of the in-plane fluctuation of the optical path length, and therefore, a method of obtaining the standard deviation by measuring the deviation from the average value is also applicable. Actually measuring the standard deviation of the in-plane distribution of the optical path length is difficult because it is difficult to measure the in-plane distribution of the thickness of the layer having irregularities, so the height distribution h ′ of the layer having irregularities is measured. Based on this, the standard deviation of the in-plane distribution of the optical path length is calculated. The height distribution h ′ of the layer having unevenness can be measured with a measuring device based on JIS B 0601 (1994). As a measuring device, for example, a surf coder MODEL SE-3500 manufactured by Kosaka Laboratory Ltd. can be used.

  Although FIG. 1 shows a configuration in which two layers are arranged between the image display unit and the protection unit, three or more layers may be arranged. However, in an embodiment in which three or more layers are arranged, the refractive index difference Δn of at least one interface is 0.01 to 0.2, and there may be a refractive index difference for other interfaces, but the refractive The rate difference Δn is also preferably 0.01 to 0.2. In addition, it is not necessary that all the interfaces having a difference in refractive index have an uneven shape, but it is preferable that at least one interface has an uneven shape. An example of an embodiment in which three or more layers are arranged is an embodiment in which an optical film having a laminated structure having a base film and a layer having an uneven surface thereon is arranged as the layer 16a.

  In the present invention, each of the image display unit and the protection unit, and the interface between the optical film and the filling layer disposed therebetween, specifically, the interface between the image display unit 10 and the layer 16a in FIG. In addition, the interface between the protection unit 12 and the layer 16b is not included in the “interface existing between the image display unit and the protection unit”. Further, in the present invention, the image display unit means a unit including a member capable of displaying an image. When a liquid crystal panel is taken as an example of the image display unit, a liquid crystal cell and polarized light disposed at least on the display surface side A unit including a membrane. In an aspect in which the liquid crystal panel is used as the image display unit, the display surface side polarizing film may be a layer adjacent to the layer 16a.

Hereinafter, details of various members usable in the liquid crystal display device of the present invention will be described.
Optical film:
In the image display device of the present invention, an optical film is disposed between the image display unit and the protection unit for the purpose of causing an interface satisfying the above condition to exist between the image display unit and the protection unit. Is preferred. The optical film may be used as a functional layer for a predetermined application in the image display device. For example, in the aspect in which the protective layer side outermost layer of the image display unit is a polarizing film and the optical film is disposed as the layer 16a in FIG. 1, the protective film that protects the polarizing film may be disposed as the layer 16a. Alternatively, a film having a laminated structure including a protective film may be disposed as the layer 16a.

  The optical film used in the present invention preferably has an uneven shape on the surface. The preferable ranges of the surface roughness Ra and the average interval Sm between the irregularities are as described above, and the surface roughness Ra is preferably 150 nm to 10000 nm, and more preferably 1000 nm to 3000 nm. Moreover, it is preferable that it is 10 micrometers-1000 micrometers, and, as for the average space | interval Sm of an unevenness | corrugation, it is more preferable that they are 20 micrometers-200 micrometers.

  The optical film having the above surface structure can be produced by various methods. An example is a method of adding translucent particles. Here, “translucent particles” refers to particles that hardly absorb visible light. The average particle diameter of the translucent particles used for the production of a film having a surface roughness Ra in the above range is preferably from 0.1 to 20 μm, more preferably from 5.0 to 20.0 μm, More preferably, it is 15 micrometers, and it is still more preferable that it is 3-15 micrometers. In the present invention, when the average particle diameter of the particles is in the above range, the stability of the surface shape is excellent. Further, it is preferable because the blackness of the screen is improved. However, since the surface property can be adjusted not only by the particle diameter of the translucent particles but also by the production method and conditions thereof, the average particle diameter of the translucent particles to be used is not limited to the above range.

  In order to adjust the refractive index difference Δn of the interface to the above range, it is not preferable to use translucent particles having an excessively high refractive index. On the other hand, the refractive index of the translucent particles to be added may be positively used in order to adjust the refractive index difference Δn at the interface within a predetermined range. From these viewpoints, the refractive index of the translucent particles to be used is preferably 1.4 to 1.7, and more preferably 1.45 to 1.55. Further, the refractive index difference with the main component polymer serving as a matrix containing the light-transmitting particles in a dispersed manner is preferably from 0.00 to 0.1 from the viewpoint of suppressing deterioration in display quality due to light scattering at the particles. From the same viewpoint, it is more preferably 0.00 to 0.02.

  Examples of optical films that can be used include both single-layered films and laminated-structured films.

  A film having a single-layer structure containing translucent particles can be produced by forming a polymer composition containing at least a main component polymer and translucent particles by a solution film-forming method or a melt film-forming method. it can. Preferably, a dope containing at least a main component polymer, translucent particles and a solvent is cast on a support, and the solvent in the dope is evaporated and dried to form a film by a solution casting method. . A film that has been subjected to post-treatment such as stretching treatment after film formation may be used.

In this embodiment, the amount of the light-transmitting ^{particles, 0.1g / m 2 ~5.0g / m} 2 are preferred per unit area, more ^{preferably, 0.2g / m 2 ~3.0g / m} 2, most preferably from ^{0.3g / m 2 ~2.0g / m 2} . By using the amount within this range, a desired surface shape can be obtained.

In addition, a film formed by a co-casting method using at least a dope containing a main component polymer and translucent particles and a dope containing the main component polymer but not containing translucent particles can also be used. When using the film produced by the co-casting method, it is preferable to arrange | position so that the surface of the layer which consists of a main component polymer and translucent particle | grains may become the said interface. The co-casting is described in detail in JP 2010-237339 A and can be referred to.
Also in the co-casting method, the preferable range of the amount of translucent particles used is the same as described above.

  Further, in the casting method, a film having a concavo-convex shape on the surface can be produced without using translucent particles or by selecting a solvent during dope preparation. By using a mixed solvent containing at least a solvent having a dielectric constant of 35 or more (preferably water) and a solvent that is incompatible with each other as a solvent at the time of preparing the dope, the surface can be used without using translucent particles. It is known that it is possible to produce films having independent, predetermined shaped indentations. In this invention, you may arrange | position the film manufactured using this method between an image display part and a protection part. When using the film manufactured by this method, it is preferable to arrange | position so that the surface which has the said hollow may become the said interface. JP-A-2009-263658 discloses a detailed description of a film production method by a casting method using a dope prepared with a mixed solvent containing a high dielectric constant solvent, and can be referred to.

  Examples of the film that can be used in the present invention include a polymer film having a concavo-convex shape formed on the surface by surface treatment. Examples of the surface treatment include a sand blasting method and an embossing method. Especially, the polymer film which has the uneven | corrugated shaped surface formed by the sandblast method is preferable.

  There is no particular limitation on the main component polymer (the ratio of the polymer exceeding 50% by mass of the solid content of the optical film raw material) that can be used in the production of the optical film having the single layer structure. A thermoplastic resin is preferable, and specific examples include cellulose acylate (for example, triacetylcellulose, diacetylcellulose, propionylcellulose, butyrylcellulose, acetylpropionylcellulose, nitrocellulose), polyamide, polycarbonate, polyester (for example, polyethylene terephthalate). , Polyethylene naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4′-dicarboxylate, polybutylene terephthalate), polystyrene (eg, syndiotactic polystyrene), polyolefin (Eg, polypropylene, polyethylene, polymethylpentene, polycycloalkane), polysulfone, polyethersulfone, polya Rate, polyetherimide, polymethylmethacrylate, polyetherketone, norbornene resin (Arton: trade name, manufactured by JSR), amorphous polyolefin (ZEONEX: trade name, manufactured by ZEON Corporation), (meth) acrylic resin (Acrypet VRL20A: trade name, manufactured by Mitsubishi Rayon Co., Ltd., ring structure-containing acrylic resin described in JP-A No. 2004-70296 and JP-A No. 2006-171464) and the like are included. Triacetyl cellulose, diacetyl cellulose, propionyl cellulose, polyethylene terephthalate and polyethylene naphthalate are particularly preferred.

In the case of producing the optical film by a solution casting method, a fatty acid ester of cellulose (cellulose acylate) is preferable from the viewpoint of ease of preparation of the solution (dope) of the main component polymer, and further triacetyl cellulose, Diacetyl cellulose and propionyl cellulose are particularly preferred.

  The translucent particles used in the production of the optical film of the above aspect may be organic fine particles or inorganic fine particles. Both inorganic particles and organic particles can be used. Examples of inorganic particles include silica and alumina. For example, Micron's spherical silica and spherical alumina can be raised. As organic particles, polymethacrylic acid methyl acrylate resin, acrylic styrene resin, polymethyl methacrylate resin, silicon resin, polystyrene resin, polycarbonate resin, benzoguanamine resin, melamine resin, polyolefin resin, polyester resin, Examples thereof include a polyamide resin, a polyimide resin, and a polyfluoroethylene resin. Commercially available products include styrene, acrylic resins, Chemisnow MX series and SX series manufactured by Soken Chemical Co., Ltd., and techpolymers manufactured by Sekisui Plastics Co., Ltd. Examples of posters and melamine resins made by Catalyst Co., Ltd. include opt-beads made by Nissan Chemical Co., Ltd. From the viewpoint of adhesion to the main component polymer, and from the viewpoints of interfacial peeling and dropping due to humidity and heat, it is preferable to use organic particles having similar expansion coefficient characteristics. The translucent particles are particularly preferably substantially spherical resin particles.

  The optical film having a single-layer structure contains a main component polymer and, if desired, translucent particles. Furthermore, other additives may be contained as desired. Examples of other additives include plasticizers, UV absorbers, deterioration inhibitors (including antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers and amines), optical additives. A directionality adjusting agent, an infrared absorber, and the like are included.

  An example of the film having a laminated structure is a film having a laminated structure having a base film made of a polymer film or the like and a layer made of a composition containing at least translucent particles thereon. For the formation of the layer, formation techniques such as an antiglare layer and a hard coat layer can be used. In one example, the composition is prepared as a coating liquid for the curable composition, applied to the surface of the base film or the surface of the layer formed thereon, and then irradiated with ionizing radiation and / or under heating. In this method, the curing reaction is advanced to form a layer. Since the light-transmitting particles are contained in the cured layer, a layer having an uneven shape on the surface can be formed by the presence of the light-transmitting particles. When using a film having this laminated structure, it is preferable to arrange the cured layer so that the surface of the cured layer is the interface. Japanese Patent Application Laid-Open No. 2010-32916 describes in detail the technology for forming an antiglare layer that can be used in the present invention.

The film having the laminated structure may be composed of three or more layers. Specifically, one or more functional layers other than the antiglare layer may be arranged on a base film made of a polymer film. Regarding the layer structure of the present invention, at least one antiglare layer and an abrasion resistant layer on the outermost surface are provided. Examples of other functional layers include a scratch-resistant layer, a hard coat layer, an antistatic layer, an antireflection layer, a low refractive index layer, and an antifouling layer.
Although the specific example of the laminated | multilayer film which can be utilized as an optical film for this invention is as follows, it is not limited to the following specific examples.
・ Base film / Anti-glare layer ・ Base film / Anti-glare layer / Abrasion resistant layer ・ Base film / Antistatic layer / Anti-glare layer / Abrasion resistant layer / Base film / Anti-glare layer / Abrasion resistance Layer (also serves as a low refractive index layer)
Base film / antiglare layer / antistatic layer / scratch resistant layerBase film / hard coat layer / antiglare layer / scratch resistant layer / base film / hard coat layer / antiglare layer / antistatic layer / Scratch resistant layer / base film / hard coat layer / antistatic layer / antiglare layer / scratch resistant layer / base film / antiglare layer / high refractive index layer / scratch resistant layer / base film / prevention Dazzle layer / Medium refractive index layer / High refractive index layer / Abrasion resistant layer / Antistatic layer / Base film / Anti-glare layer / Medium refractive index layer / High refractive index layer / Abrasion resistant layer / Base film / Charge Prevention layer / Anti-glare layer / Medium refractive index layer / High refractive index layer / Abrasion resistant layer / Antistatic layer / Base film / Anti-glare layer / High refractive index layer / Low refractive index layer / High refractive index layer / Anti-resistant Scratch Layer Details of these functional layers are described in JP 2010-32916 A and can be referred to.

Antiglare layer:
The refractive index of the antiglare layer is preferably 1.4 to 1.6, and more preferably 1.45 to 1.55. Moreover, it is preferable that the surface has a concavo-convex shape in which the surface roughness Ra and the average interval of the concavo-convex are in the above ranges. On the other hand, an interface also exists between the base film and the antiglare layer, but there is no particular limitation on the difference in refractive index between the interfaces. When the interface has an uneven shape, the refractive index difference is preferably small, and is preferably within the above range, that is, 0.01 to 0.2. In an aspect in which another functional layer is disposed on the antiglare layer or between the antiglare layer and the base film, between the antiglare layer and the functional layer, or between the base film and the functional layer, In the aspect having two or more functional layers, there may be an interface between the functional layers. The refractive index difference Δn of the interface is not particularly limited, but when the interface has an uneven shape, the refractive index difference is preferably small and is preferably within the above range, that is, 0.01 to 0.2. .

In the production of the optical film having the laminated structure, examples of materials used for forming the antiglare layer and examples of the forming method are as follows.
The antiglare layer is formed by applying a coating liquid containing at least a translucent particle and a matrix polymer containing the dispersed particles (which may be a polymerizable monomer serving as a matrix polymer) to the surface of a substrate film, etc. It can be formed by drying and curing. Although there is no restriction | limiting in particular about the thickness of an anti-glare layer, Generally, it is preferable that it is about 1-40 micrometers.

  The preferable range of the average particle diameter of the translucent particles used for forming the antiglare layer is as described above. Translucent particles having a uniform average particle diameter may be used, or two or more kinds of particles having different average particle diameters may be used. The average particle size of the translucent particles that can be used is the primary particle size regardless of whether two or more particles are present adjacent to each other in the coating film or independently. Means. However, when the agglomerated inorganic particles having a primary particle size of about 0.1 μm are dispersed as secondary particles in the coating liquid and then applied, the size of the secondary particles is set.

  A lower internal scattering property in the antiglare layer is preferable. In order to obtain the necessary internal scattering properties, it is preferable to adjust the refractive index between the particles and the matrix, and the difference in refractive index between the at least one kind of particles and the matrix is preferably 0.0 to 0.05, More preferably, it is 0.0-0.02, More preferably, it is 0.0-0.01.

  1-60 mass% in the total solid of the formation material of an anti-glare layer is preferable, as for the addition amount of particle | grains, it is still more preferable that it is 2-50 mass%, More preferably, it is 3-40 mass%. When the particles are in this ratio, the effect of reducing the variation of the surface morphology of the coating film accompanying the change with time of the coating solution is excellent.

Examples of translucent particles that can be used to form the antiglare layer include resin particles and inorganic fine particles. Specific examples of the resin particles include, for example, crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles, crosslinked polystyrene particles, crosslinked methyl methacrylate-methyl acrylate copolymer particles, crosslinked acrylate-styrene copolymer particles, Preferred examples include resin particles such as melamine / formaldehyde resin particles and benzoguanamine / formaldehyde resin particles. Of these, crosslinked styrene particles, crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles, and the like are preferable. Furthermore, the surface of these resin particles is a so-called surface-modified particle in which a compound containing a fluorine atom, a silicon atom, a carboxyl group, a hydroxyl group, an amino group, an sulfonic acid group, a phosphoric acid group, or the like is chemically bonded. The particle | grains which couple | bonded the inorganic fine particle of the size to the surface are also mentioned preferably. Moreover, inorganic fine particles can also be used as the translucent particles. Specific examples of the inorganic fine particles include silica particles and alumina particles, and silica particles are particularly preferably used.
As the shape of the particle, either a true sphere or an irregular shape can be used.

  For the formation of the antiglare layer, a polymer and / or monomer serving as a matrix containing light-transmitting particles in a dispersed manner is used. It is preferable to use a polymer that cures under the supply of ionizing radiation and / or heat, and it is preferable to use a monomer that forms a light-transmitting polymer having a saturated hydrocarbon chain or a polyether chain as the main chain after curing. . Moreover, it is preferable that the main binder polymer after hardening has a crosslinked structure.

  As the binder polymer having a saturated hydrocarbon chain as a main chain after curing, an ethylenically unsaturated monomer selected from compounds of the first group described below and a polymer thereof are preferable. Moreover, as a polymer which has a polyether chain as a principal chain, the epoxy-type monomer chosen from the compound of the 2nd group described below and the polymer by these ring-opening are preferable. Furthermore, a polymer of a mixture of these monomers is also preferable.

  As the first group of compounds, the binder polymer having a saturated hydrocarbon chain as the main chain and having a crosslinked structure is preferably a (co) polymer of monomers having two or more ethylenically unsaturated groups. In order to obtain a high refractive index, the monomer structure preferably contains at least one selected from an aromatic ring, a halogen atom other than fluorine, a sulfur atom, a phosphorus atom, and a nitrogen atom.

As a monomer having two or more ethylenically unsaturated groups used for forming a binder polymer that can be used for forming the antiglare layer, an ester of a polyhydric alcohol and (meth) acrylic acid {for example, ethylene glycol Di (meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipenta Erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-chlorohexane Tramethacrylate, polyurethane polyacrylate, polyester polyacrylate}, vinylbenzene and derivatives thereof (for example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone ( For example, divinyl sulfone), (meth) acrylamide (for example, methylenebisacrylamide) and the like can be mentioned.
Furthermore, resins having two or more ethylenically unsaturated groups, such as relatively low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins And oligomers or prepolymers such as polyfunctional compounds such as polyhydric alcohols. Two or more of these monomers may be used in combination, and the resin having two or more ethylenically unsaturated groups is preferably contained in an amount of 10 to 100% based on the total amount of the binder.

  Polymerization of the monomer having an ethylenically unsaturated group can be performed by irradiation with ionizing radiation or heating in the presence of a photoradical polymerization initiator or a thermal radical polymerization initiator. Accordingly, a coating solution containing a monomer having an ethylenically unsaturated group, a photo radical polymerization initiator or a thermal radical polymerization initiator, and particles, and if necessary, an inorganic filler, a coating aid, other additives, an organic solvent and the like. After the coating liquid is applied to the surface of the base film or the layer formed thereon, the polymerization reaction is allowed to proceed under the supply of light and / or heat to cure and form an antiglare layer can do. Various photopolymerization initiators and thermal polymerization initiators can be used, and commercially available compounds may be used. They are described in the catalog of “Latest UV Curing Technology” (p.159, publisher: Kazuhiro Takasagi, publisher; Technical Information Association, Inc., published in 1991) and Ciba Specialty Chemicals Co., Ltd. ing.

As the second group of compounds, it is preferable to use an epoxy compound described below in order to reduce curing shrinkage of the cured film. As these monomers having an epoxy group, monomers having two or more epoxy groups in one molecule are preferable, and examples thereof include JP-A Nos. 2004-264563, 2004-264564, and 2005-37737, Examples thereof include epoxy monomers described in JP-A-2005-37738, JP-A-2005-140862, JP-A-2005-140863, and JP-A-2002-322430.
The monomer having an epoxy group is preferably contained in an amount of 20 to 100% by mass with respect to all binders constituting the layer in order to reduce curing shrinkage, more preferably 35 to 100% by mass, and more preferably 50 to 100% by mass. It is more preferable to contain.

Examples of photoacid generators that generate cations by the action of light for polymerizing epoxy monomers and compounds include ionic compounds such as triarylsulfonium salts and diaryliodonium salts, and nitrobenzyl esters of sulfonic acids. Non-ionic compounds and the like can be used, and various known photoacid generators such as compounds described in “Organic Materials for Imaging” published by Bunshin Publishing Co., Ltd. (1997) can be used. . Among these, a sulfonium salt or an iodonium salt is particularly preferable, and PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , B (C ₆ F ₅ ) ₄ ^{− and the} like are preferable as a counter ion.

  The polymerization initiator is preferably used in a range of 0.1 to 15 parts by mass with respect to 100 parts by mass of the compound of the first group or the second group in the total amount of the polymerization initiator. Is more preferable.

For the formation of the antiglare layer, a polymer compound may be used. By adding a polymer compound, curing shrinkage can be reduced, and the viscosity of the coating solution can be adjusted.
Examples of the polymer compound that can be used include cellulose esters (eg, cellulose triacetate, cellulose diacetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate), urethane acrylates, Polyester acrylates, (meth) acrylic acid esters (for example, methyl methacrylate / (meth) methyl acrylate copolymer, methyl methacrylate / (meth) ethyl acrylate copolymer, methyl methacrylate / (meth) acrylic) Examples include resins such as butyl acid copolymer, methyl methacrylate / styrene copolymer, methyl methacrylate / (meth) acrylic acid copolymer, polymethyl methacrylate) and polystyrene.

  The polymer compound is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, based on the total binder contained in the antiglare layer, from the viewpoint of effect on curing shrinkage and the effect of increasing the viscosity of the coating solution. It is preferable to contain in the range. Further, the molecular weight of the polymer compound is preferably from 30,000 to 400,000 in terms of mass average, more preferably from 50,000 to 300,000, and even more preferably from 50,000 to 200,000.

  In addition to the above-mentioned translucent particles, the antiglare layer has an inorganic filler depending on the purpose of adjusting the refractive index, adjusting the film strength, reducing curing shrinkage, and reducing the reflectance when a low refractive index layer is provided. It may be added. Examples of the inorganic filler that can be used include an oxide containing at least one metal element selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony. It is also preferable to contain a fine high refractive index inorganic filler that is generally 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.06 μm or less and 1 nm or more.

  In an embodiment using an optical film having the antiglare layer, the interface with the other layers of the antiglare layer (for example, the interface with the resin-filled layer formed between the image display unit and the protective unit) If the difference in refractive index at the interface with other functional layers or the base polymer film is too large, the effects of the present invention may be impaired. In such a case, it is preferable to adjust the refractive index difference of the antiglare layer to reduce the refractive index difference Δn at the interface with other layers (for example, 0.01 to 0.2). For example, when it is necessary to lower the refractive index of the matrix, a fine low refractive index inorganic filler such as silica fine particles or hollow silica fine particles can be used as the inorganic filler. In addition, when it is necessary to increase the refractive index of the matrix, the inorganic filler is fine as an oxide containing at least one metal element selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony. A high refractive index inorganic filler can be used. The particle size of the inorganic filler is preferably smaller from the viewpoint of suppressing light scattering, but if it is too small, the viscosity of the coating solution increases. Therefore, the average particle diameter of the primary particles is generally 0.001 μm or more and 0.2 μm or less, preferably 0.001 μm or more and 0.1 μm or less, more preferably 0.001 μm or more and 0.06 μm or less. . Since the particle size range is sufficiently shorter than the wavelength of light, the antiglare layer containing the inorganic filler in the particle size range does not scatter, and the dispersion in which the filler is dispersed in the binder polymer is optically uniform. It has the properties of a new substance.

The surface of the inorganic filler is preferably subjected to a silane coupling treatment or a titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with a binder species on the filler surface is preferably used.
The added amount of the inorganic filler is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and particularly preferably 30 to 75% by mass with respect to the total mass of the antiglare layer.

A surfactant may be added to the coating composition used for forming the antiglare layer. Surfactants will be used to reduce coating unevenness, drying unevenness, point defects, and the like. From these viewpoints, it is preferable to use at least one of a fluorine-based surfactant and a silicone-based surfactant. In particular, a fluorosurfactant is preferable because it is effective with a smaller addition amount. Preferable examples of the fluorine-based surfactant that can be used include the compounds described in paragraph numbers 0049 to 0074 of JP-A-2007-188070.
The preferable addition amount of the surfactant (particularly the fluorine-based polymer) added to the coating composition for forming the antiglare layer is in the range of 0.001 to 5% by mass, preferably 0. The range is 0.005 to 3% by mass, and more preferably 0.01 to 1% by mass.

  An organic solvent can be used for the preparation of the coating composition used for forming the antiglare layer. Examples of organic solvents include alcohol, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, isoamyl alcohol, 1-pentanol, n-hexanol, methyl amyl Alcohol, etc. For ketones, methyl isobutyl ketone, methyl ethyl ketone, diethyl ketone, acetone, cyclohexanone, diacetone alcohol, etc. For esters, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, isobutyl acetate, n-butyl acetate , Isoamyl acetate, n-amyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl acetate, methyl lactate, ethyl lactate, ether, acetal, 1,4 dioxane, tetra In hydrocarbons such as lofuran, 2-methylfuran, tetrahydropyran, diethyl acetal, etc., hexane, heptane, octane, isooctane, ligroin, cyclohexane, methylcyclohexane, toluene, xylene, ethylbenzene, styrene, divinylbenzene, etc., halogen hydrocarbons In, carbon tetrachloride, chloroform, methylene chloride, ethylene chloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, tetrachloroethylene, 1,1,1,2-tetrachloroethane In the polyhydric alcohol and derivatives thereof, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoacetate, diethylene glycol, propylene Recall, dipropylene glycol, butanediol, hexylene glycol, 1,5-pentanediol, glycerin monoacetate, glycerin ethers, 1,2,6-hexanetriol, etc. In fatty acid systems, formic acid, acetic acid, propionic acid, entanglement In the case of nitrogen, compounds such as formamide, N, N-dimethylformamide, acetamide, acetonitrile, etc., in the case of sulfur compounds, dimethyl sulfoxide, etc. are included.

  Among organic solvents, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, acetone, toluene, xylene, ethyl acetate, 1-pentanol and the like are particularly preferable. In addition, an alcohol or a polyhydric alcohol solvent may be appropriately mixed with the organic solvent for the purpose of controlling cohesion. These organic solvents may be used alone or in combination, and the coating composition preferably contains 20 wt% to 90 wt%, and preferably 30 wt% to 80 wt% as the total amount of the organic solvent. More preferably, it is more preferably 40 to 70% by weight. In order to stabilize the surface shape of the antiglare layer, it is preferable to use a solvent having a boiling point of less than 100 ° C. and a solvent having a boiling point of 100 ° C. or more in combination.

An example of the method for forming the antiglare layer is as follows. However, it is not limited to this method.
First, a coating solution containing components for forming an antiglare layer is prepared. Next, this coating liquid is apply | coated to the surface of the layer formed on the base film or the base film. As a coating method, a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, a die coating method and the like are preferable, and a micro gravure coating method, a wire bar coating method, a die coating method ( U.S. Pat. No. 2,681,294 and JP-A-2006-122889) are more preferred, and the die coating method is particularly preferred.

After coating, the coating is dried to remove the solvent and form a coating film. Drying may be performed under heating.
Next, the curing reaction of the components in the coating film is allowed to proceed and cure to form an antiglare layer. The curing reaction can proceed under irradiation with ionizing radiation and / or under heating. More specifically, light curing, electron beam irradiation, heat treatment and the like can be performed to advance the curing reaction. Examples of the curing reaction include a crosslinking reaction and a polymerization reaction.

  In the case of ultraviolet irradiation, ultraviolet rays emitted from light such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. can be used. Curing with ultraviolet rays is preferably carried out by nitrogen purge or the like in an atmosphere having an oxygen concentration of 4% by volume or less, more preferably 2% by volume or less, and most preferably 0.5% by volume or less.

  After forming the antiglare layer or before forming it, another functional layer such as a scratch-resistant layer may be formed on the surface of the antiglare layer as desired. The method for forming the other functional layer is the same as the method for forming the antiglare layer. Examples of other functional layers are as described above, and for materials used for forming each functional layer, the description in JP-A-2001-32916 can be referred to.

As the base film for supporting the antiglare layer, it is preferable to use a plastic film. Examples of the polymer forming the plastic film include cellulose acylate (eg, triacetyl cellulose, diacetyl cellulose, typically TAC-TD80U, TD80UF, etc., manufactured by Fuji Film), polyamide, polycarbonate, polyester (eg, polyethylene terephthalate, polyethylene). Naphthalate), polystyrene, polyolefin, norbornene resin (Arton: trade name, manufactured by JSR), amorphous polyolefin (ZEONEX: trade name, manufactured by ZEON CORPORATION), (meth) acrylic resin (ACRYPET VRL20A: product) Name, manufactured by Mitsubishi Rayon Co., Ltd., ring structure-containing acrylic resin described in JP-A No. 2004-70296 and JP-A No. 2006-171464), and the like. Of these, triacetyl cellulose, polyethylene terephthalate, and polyethylene naphthalate are preferable, and triacetyl cellulose is particularly preferable.
The thickness of the base film is usually about 25 μm to 1000 μm, preferably 25 μm to 250 μm, and more preferably 30 μm to 90 μm.

  Although the arbitrary width | variety of a base film can be used, the thing of 100-5000 mm is normally used from the point of handling, a yield, and productivity, and it is preferable that it is 800-3000 mm, and is 1000-2000 mm. More preferably it is. The base film can be handled in a roll form and is usually 100 m to 5000 m, preferably 500 m to 3000 m.

  As the base film, a plastic film having a smooth surface can be used. Specifically, a plastic film having an average roughness Ra of 1 μm or less, 0.0001 to 0.5 μm, or 0.001 to 0.1 μm can be used.

  As described above, in the aspect in which the optical film is disposed between the image display unit and the protection unit, the optical film may be used as a functional layer for a predetermined application in the image display device. For example, in an aspect in which the protective layer side outermost layer of the image display unit is a polarizing film, the optical film may be a protective film for the polarizing film. When the main component polymer of the optical film is triacetyl cellulose, or when the main component polymer of the base film constituting the optical film is triacetyl cellulose, it is suitable as a protective film for a polarizing film.

  In an aspect in which the optical film is used as a protective film for a polarizing plate, in order to sufficiently bond the optical film, a surface to be bonded to the polarizing film of the optical film (in an aspect having an antiglare layer or the like, an antiglare layer or the like is provided). It is preferable to perform a saponification treatment on the surface not formed). In the embodiment of the laminated structure having an antiglare layer or the like, it is preferable to carry out a saponification treatment after forming the antiglare layer or the like. The saponification treatment may be performed by a known method, for example, by immersing the film in an alkaline solution for an appropriate time. After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by dipping in a dilute acid so that the alkaline component does not remain in the film. By saponification treatment, it can be hydrophilized and the adhesion to the polarizing film is improved. The saponification treatment is preferably performed so that the contact angle with water is 40 ° or less. More preferably, it is 30 ° or less, particularly preferably 20 ° or less.

Packing layer:
The image display device of the present invention preferably has a filling layer between the image display unit and the protection unit. As the filling layer, a material obtained by curing a pressure-sensitive adhesive, an adhesive, or a curable resin composition can be used. In particular, a material obtained by curing a curable resin composition is preferable. An aspect of the image display device of the present invention is an image display unit and a protection unit, wherein the optical film having a concavo-convex shape is disposed on the surface of the image display unit, and the optical film is protected It is an aspect which has a filling layer formed by filling and curing the curable resin composition in the gap between the parts. In this aspect, the adjacent surface of the optical film and the filling layer is an interface having a refractive index difference Δn of 0.01 to 0.2, and the interface has an uneven shape, whereby the optical path length is predetermined in the surface. It is preferable that it is distributed in the range.

  Examples of the filling layer using a material obtained by curing the curable resin composition include a layer made of a cured product of a photocurable resin composition containing a polymer and an acrylate monomer. Examples of the polymer having a polymerizable group that can be used for forming the packed layer include polyurethane acrylate, polyisoprene acrylate or an ester compound thereof, terpene hydrogenated resin, butadiene polymer, and the like. Examples of the monomer having a polymerizable group that can be used for forming the packed layer include isobornyl acrylate, dicyclopentenyloxyethyl methacrylate, 2-hydroxybutyl methacrylate, and the like.

  The curable composition preferably contains a polymerization initiator. Examples of usable polymerization initiators include photopolymerization initiators such as 1-hydroxy-cyclohexyl-phenyl-ketone. However, it is not limited to these examples, It can select according to the kind of polymer and monomer which have a polymeric group used. A thermal polymerization initiator may be used.

The filling layer fills the gap between the optical film disposed on the image display portion and the protective portion with the curable composition, and cures under irradiation with light such as ultraviolet rays and / or under heating. It can be formed by proceeding and curing.
Although there is no restriction | limiting in particular about the thickness of the filling layer formed, The thickness of the filling layer formed will be about 50-1000 micrometers. However, it is not limited to this range.

  The refractive index of the filling layer is not particularly limited, but if the refractive index difference Δn between the filling layer and the protective part (generally a glass substrate and the refractive index is about 1.5) is too large, Since problems, such as a display quality fall by interface reflection, arise, it is preferable that it is 1.45-1.55, and it is more preferable that it is 1.47-1.53. However, the difference Δn between the refractive index of the optical film to be used in combination (the refractive index of the outermost layer adjacent to the filling layer in the case where the optical film has a laminated structure) should be 0.01 to 0.2. The range is not limited.

Image display:
The image display unit of the image display device of the present invention includes a liquid crystal panel of a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD) panel, a cathode ray tube display device (CRT), a surface electric field display ( Various image display panels such as SED) panels can be used. Particularly preferred is a liquid crystal panel of a liquid crystal display device (LCD). The mode of the liquid crystal panel is not particularly limited, and the effects of the present invention can be obtained. Various modes such as twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optically compensated bend cell (OCB), transmission type, reflection type, Alternatively, a transflective liquid crystal panel can be used.

  In an aspect in which a liquid crystal panel is used as the image display unit, an example of the image display unit includes at least a liquid crystal cell and a pair of polarizing films disposed above and below the liquid crystal cell. Between the liquid crystal cell and both or one of the pair of polarizing films, a polymer film such as an optical compensation film or a protective film for the polarizing film may be disposed. Moreover, the polymer film etc. which function as a protective film of a polarizing film may be arrange | positioned in the further outer side of each of a pair of polarizing film. Moreover, as described above, an optical film having the uneven shape on the surface may be disposed as a protective film for the polarizing film disposed on the protective portion side.

Protection part:
The protection unit included in the image display device of the present invention is translucent. Here, “translucency” means
It means that it absorbs almost no visible light. The protective part is formed of a plate-like, sheet-like, or film-like translucent member having the same size as the image display part. Examples of the translucent member that can be used as the protective part include optical glass and plastic (acrylic resin such as polymethyl methacrylate). An antireflection film, a light shielding film, a viewing angle control film, or the like may be disposed on the front surface or the back surface of the protective portion.

  The image display device of the present invention can be used as an image display device for various uses such as a television display device, a monitor, a signage, a touch panel display device, a personal computer display device, and a mobile phone display device. In particular, having a protective part is excellent in aesthetics, so it is suitable for applications such as video viewing.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

1. Manufacture of an optical film The optical film of the laminated structure which has a glare-proof layer on a base film was manufactured with the following method, respectively.
(1) Preparation of base film A commercially available acetyl cellulose film ("TAC-TD80U" manufactured by FUJIFILM Corporation) having a long thickness of 80 µm wound in a roll form was prepared.

(2) Formation of antiglare layer Coating solutions having the compositions described in the following table were prepared. The numerical value in the following table means mass%. Moreover, the particle | grains 1 and the particle | grains 2 in the following table | surface are respectively as follows.
Particle 1:
30 mass% MIBK dispersion of crosslinked acrylic / styrene particles having an average particle size of 8.0 μm [manufactured by Sekisui Plastics Co., Ltd.], which is prepared by dispersing for 20 minutes at 10,000 rpm in a polytron disperser liquid. The refractive index of the particles is 1.555.
Particle 2:
30% by weight MIBK dispersion of particles having an average particle size of 5 μm from Eposter M05 (benzoguanamine / formaldehyde condensate, manufactured by Nippon Shokubai Co., Ltd.), and prepared by dispersing for 20 minutes at 10,000 rpm in a polytron disperser Dispersion. The refractive index of the particles is 1.66.

In addition, the meanings of the symbols in the following table are as follows.
DPHA: a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate [manufactured by Nippon Kayaku Co., Ltd.];
Z7404: Hard coating agent containing ZrO ₂ fine particles (Desolite Z7404 [refractive index 1.72, solid content concentration: 60% by mass, zirconium oxide fine particle content: 70% by mass (solid content), average particle diameter of zirconium oxide fine particles: about 20 nm, solvent composition: MIBK / MEK = 9/1, manufactured by JSR Corporation]);
Irg127: polymerization initiator (Irgacure 127 [Ciba Specialty Chemicals Co., Ltd.]);
MIBK: methyl isobutyl ketone;
MEK: methyl ethyl ketone;
SP-13: Fluorine-based surfactant having the following structure (used after dissolving as a 10% by mass solution of MEK)

The film in the roll form is unwound, and each coating solution having the above composition is transferred by a die coating method using a slot die (similar to the slot die used in Example 1 of Japanese Patent Laid-Open No. 2006-122889). After applying at 30 m / min, drying at 60 ° C. for 150 seconds, and further using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with an oxygen concentration of about 0.1% under a nitrogen purge, An antiglare layer was formed by irradiating ultraviolet rays having an illuminance of 400 mW / cm ² and an irradiation amount of 100 mJ / cm ² to cure the coating layer.
The thickness of the binder part of each antiglare layer formed was 4 μm for Examples 1-2 and Comparative Example 3, 2 μm for Examples 3-4 and Comparative Example 4, and 10 μm for Comparative Example 2, It was set as the said thickness by adjusting quantity. The optical film used in Comparative Example 1 did not form an antiglare layer, that is, a commercially available cellulose acetate film was used as it was.

  Thus, each optical film was manufactured. Details and results of measurement of the characteristics of each optical film will be described later.

(3) Saponification treatment of optical film Each optical film produced above was subjected to saponification treatment under the following conditions.
First, a 1.5 mol / L sodium hydroxide aqueous solution was prepared and kept at 55 ° C. A 0.01 mol / L dilute sulfuric acid aqueous solution was prepared and kept at 35 ° C. Each of the produced optical films was immersed in the aqueous sodium hydroxide solution for 2 minutes and then immersed in water to sufficiently wash away the aqueous sodium hydroxide solution. Subsequently, after being immersed in the above-mentioned dilute sulfuric acid aqueous solution for 1 minute, it was immersed in water to sufficiently wash away the dilute sulfuric acid aqueous solution. Finally, each film was sufficiently dried at a temperature of 120 ° C. Thus, each saponified optical film was produced.

2. Production of Polarizing Plate A commercially available acetyl cellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd.) having a thickness of 80 μm was prepared, immersed in an aqueous NaOH solution of 1.5 mol / L, 55 ° C. for 2 minutes, Washed with water and water.
Separately, a polarizing film prepared by adsorbing iodine on a polyvinyl alcohol film and stretching it was prepared.
Each optical film after saponification treatment was adhered to one surface of the polarizing film, and the acetylcellulose film after saponification treatment was adhered to the other surface to produce a polarizing plate.
Thus, each polarizing plate was produced.

3. Production of Image Display Device For a commercially available IPS mode liquid crystal display device, the polarizing plate on the front side was peeled off, and each of the produced polarizing plates was bonded so that the antiglare layer was on the front side. An adhesive was used for pasting.
Corning EAGLE XG having a thickness of 0.5 mm was prepared as a protective part, and it was placed and fixed on an optical film adhered on a liquid crystal cell via a spacer. The gap between the optical film and the protective part was 1 mm.

A space between the protective part and the optical film was filled with a curable resin composition having the following composition.
Composition of curable resin composition for packed bed:
Polyisoprene polymer maleate anhydride adduct and 2-hydroxyethyl methacrylate 100 parts by weight Dicyclopentenyloxyethyl methacrylate 30 parts by weight 2-hydroxybutyl methacrylate 10 parts by weight Terpene-based hydrogenated resin 30 parts by weight Butadiene heavy 210 parts by weight of photopolymerization initiator (trade name Irgacure 184, manufactured by Ciba Specialty Chemicals)
7 parts by weight

The curable resin composition filled in the voids was conveyed by a UV conveyor and irradiated with ultraviolet rays, and the curing reaction was advanced to form a packed layer. The refractive index of this filling layer is shown in the following table.
In this manner, an image display device having the same configuration as in FIG. 1 was produced using each of the optical films produced above.
However, in Comparative Example 2, no protective part was arranged.

4). Evaluation (1) Refractive Index of Optical Film and Filling Layer The refractive index of the optical film and filling layer was measured using an Abbe refractometer by separately preparing a sample with a smooth surface. About each optical film, the coating liquid which extracted the translucent particle | grains from each coating liquid composition for glare-proof layers was created, the coating liquid was apply | coated on the glass substrate, and it was made to harden | cure on the same conditions as an anti-glare layer. Moreover, about the filling layer, after apply | coating the same coating liquid as a filling layer on a glass substrate, it conveyed with the UV conveyor and irradiated with the ultraviolet-ray and was hardened.
(2) Measurement of surface property of optical film Ra of the surface of the antiglare layer of each optical film produced above was measured using VertScan 2.0 manufactured by Ryoka System.

(3) In-plane standard deviation of the optical path length between the image display unit and the protection unit The RMS (root mean square roughness) of the surface of the antiglare layer of each optical film produced above is VertScan2. Measured using 0. The refractive index difference of the layer between the optical film, the protective film and the optical film was Δn, and the in-plane standard deviation was calculated using the formula σ = Δn × RMS.

(4) Evaluation of image display device (optical characteristic evaluation method)
Separately, evaluation samples were prepared by the following methods.
Each optical film was affixed on the glass 1 via an adhesive, and the curable resin composition having the above composition was applied to the outermost surface except for Comparative Example 2. The glass 2 was placed thereon and sealed, and irradiated with ultraviolet rays to cure the curable resin composition to form a filling layer. The back side of the adhesive of Glass 1 was painted with black paint.
-Specular reflectance, integrating sphere reflectance Measured using an ultraviolet-visible spectrophotometer V550 manufactured by JASCO. The smaller the value of the integrating sphere reflectivity, the better the image display device has better black tightening in a bright room environment.
-Image clarity It measured using Suga Test Instruments' image clarity measuring device ICM-1T. The evaluation value of image clarity of optical comb teeth of 0.125 mm is shown in the table. A smaller value indicates that the image display apparatus is less likely to generate an iridescent diffraction pattern.

(5) Evaluation of image display device (visual evaluation method)
Each image display device was installed in a room equipped with a fluorescent lamp (TOSHIBA fluorescent lamp FHF32E) on a ceiling with a height of 2.5 m, and the rainbow-color diffraction pattern and black tightening were visually evaluated.
-Rainbow color diffraction pattern Visual evaluation of the diffraction rainbow was carried out according to the following criteria, based on whether or not a rainbow color pattern was visible around the fluorescent light by reflecting a fluorescent lamp on the ceiling on the display surface.
◎ Invisible ○ Slightly visible × Clearly visible / Black tightening Visual evaluation of black tightening was performed by observing the image display device from the front and evaluating the blackness of the screen. For comparison, a glass plate (hereinafter referred to as black glass) whose back was painted with black paint was placed next to each image display device, and the blackness was compared.
◎ Equivalent to black glass ○ Slightly whiter than black glass × Whiter than black glass

  The results of the above evaluations are shown in the following table.

From the results shown in the above table, it can be understood that the image display device of the present invention is an image display device with excellent display characteristics that exhibits excellent black tightening and a reduced iridescent diffraction pattern.
On the other hand, in the image display device of Comparative Example 1 in which the optical path length between the image display unit and the protection unit is uniform in the plane, the rainbow color solution pattern is observed, and the display characteristics are remarkably worse than in the example. It was.
Further, in Comparative Example 2 in which no protective part was arranged, the black tightening was poor and the entire screen was whitish.
In Comparative Examples 3 and 4, since an optical film having an antiglare layer is disposed between the image display unit and the protection unit, an interface having a refractive index difference Δn of 0.01 to 0.2 exists. In addition, although the optical path length was also distributed in the plane, the standard deviation was outside the range of the present invention, so the effect of reducing the iridescent diffraction pattern could not be obtained.

DESCRIPTION OF SYMBOLS 10 Image display part 12 Protection part 16a Optical film 16b Packing layer s Interface

Claims (11)

An image display device having an image display unit, and a translucent protection unit disposed on the image display unit,
An interface having a refractive index difference Δn of 0.01 to 0.2 exists between the image display unit and the protection unit, and an in-plane optical path length between the image display unit and the protection unit A standard deviation σ of distribution is 40 nm or more. The image display device according to claim 1, further comprising an optical film between the image display unit and the protection unit, wherein the interface is an adjacent surface between the optical film and a layer adjacent thereto. . The image display device according to claim 2, wherein a surface roughness Ra of an adjacent surface of the optical film is 150 nm to 10,000 nm. 4. The image display device according to claim 2, wherein an average interval of unevenness of adjacent surfaces of the optical film is 10 μm to 1000 μm. The image display device according to claim 4, wherein the optical film contains translucent particles. The image display device according to claim 5, wherein an average particle diameter of the translucent particles is 5.0 to 20.0 μm. The image according to any one of claims 2 to 6, wherein the optical film is a film having a laminated structure including a base film and a layer containing at least translucent particles thereon. Display device. The image display device according to claim 2, wherein an adjacent surface of the optical film is sandblasted. The image display device according to claim 2, wherein the optical film is made of or includes a film produced by a casting method. The image display device according to claim 2, wherein the optical film is a protective film for a polarizing plate. The image display device according to claim 2, wherein the layer adjacent to the optical film is a filling layer made of a curable resin composition.

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