JPH10282312A - Interference fringes elimination sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet to eliminate the interference fringes generated in the image display surface in an image display device having a protective plate. SOLUTION: In an interference fringes elimination sheet provided with a layer having fine irregularity consisting of the hardened film of the energy ray hardening resin composition containing particles on a transparent film, the haze value of the interference fringes elimination sheet is 1-5%, and the visibility of the transmitted image is >=40% at the optical comb width of 0.05 mm in the image clarity measuring instrument. Generation of the interference fringes is prevented by using the sheet for a protective sheet for the plasma display or a touch panel, providing the display surface easier to watch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an interference fringe eliminating sheet used for an image display device.

[0002]

2. Description of the Related Art In recent years, a plasma display (hereinafter abbreviated as PDP) has been used as a large-screen and high-definition image display device.
Development is progressing rapidly. The PDP generates heat due to light emission by plasma and generates infrared rays and electromagnetic waves. For this reason, a protective plate for cutting electromagnetic waves and infrared rays is provided on the front surface of the display screen via an air layer to promote heat radiation.

[0003]

However, when these protective plates are arranged via an image display surface and an air layer, light interference fringes, so-called Newton rings, formed by a thin layer of air sandwiched between the protective plates. This causes a problem that the visibility of the displayed image is reduced.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of such a situation, and as a result, by disposing a film having fine irregularities on the image display surface side of the protective plate, the above problem has been solved. The present inventors have found that the point can be solved, and have reached the present invention. That is, the present invention provides (1) an interference fringe eliminating sheet in which a layer having fine irregularities formed of a cured film of an energy ray-curable resin composition containing fine particles is provided on a transparent film. (2) Optical comb width 2 wherein the haze value of the sheet is 1 to 5% and the transmitted image sharpness at an optical comb width of 0.05 mm in an image clarity measuring device is 40% or more; The interference fringe eliminating sheet according to (1), wherein the transmitted image definition at 0.0 mm is 80% or more, and (3) a fluororesin layer or a multilayer antireflection film is formed on the surface of the layer having irregularities (1). Or the interference fringe eliminating sheet according to (2). (4) An interference fringe eliminating sheet provided with a layer having fine irregularities formed of a cured film of an energy ray-curable resin composition containing fine particles on a transparent film, wherein the haze value of the interference fringe eliminating sheet is 1 to 5% and an optical comb width of 0.
An image display device in which a sheet having a transmitted image definition of at least 40% at 05 mm is disposed on the front surface of a display surface with a layer having fine irregularities inside. (5) The image display device according to (4), wherein the sheet is in contact with the display unit without being bonded, (6) the image display device is a plasma display or a liquid crystal display device (4) or (5). The image display device as described in the above. (7) The image display device according to (4) or (5), wherein the image display device is a touch panel.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The interference fringe eliminating sheet of the present invention is a cured film having fine irregularities obtained by curing a transparent film and an energy ray-curable resin composition containing fine particles formed thereon. And a light scattering property (haze value) of 1 to 5%, more preferably about 1 to 3%, and a transmitted image sharpness at an optical comb width of 0.05 mm in an image clarity measuring device of 40% or more. It is preferably at least 50%. Further, it is more preferable that the transmitted image clarity at an optical comb width of 2.0 mm is 80% or more, preferably 90% or more. The image clarity measuring device is a device for measuring how sharp a transmitted image is. The higher this value, the clearer the image transmitted through the sheet.

The fine particles used in the present invention include, for example, silica fine particles or polymer compound fine particles surface-treated with an organic substance. It is preferable that the silica fine particles or the fine particles composed of a polymer compound have excellent dispersibility in an energy ray-curable resin composition and a solvent that dissolves the resin. Preferably it has been treated.
Examples of the organic substance that can be used include a wax, a silane coupling agent, chlorosilane, and an alkoxide compound.

[0007] In order to maintain a sufficient clearness of the transmitted image, the average particle diameter by the Coulter counter method is 0.5 to 3 µm, preferably about 1.0 to 2.0 µm. This average particle diameter is an average secondary particle diameter when it is composed of secondary particles. It is also possible to use a mixture of these fine particles having different average particle sizes.

Further, if the compounding amount is too large, the haze value may increase and the transmitted image definition may decrease, so that the light scattering property (haze value) is preferably 1 to 5.
%, More preferably about 1.5 to 4%, for example, preferably about 0.01 to 2 parts by weight based on 100 parts by weight of the resin component of the energy ray-curable resin composition.

The energy ray-curable resin composition includes:
Acrylic, urethane, acrylic urethane, epoxy, silicone-based reactive compounds, etc.
In the case of curing using ultraviolet rays, a photopolymerization initiator is usually blended with the composition for use. The cured film layer in the present invention is preferably a film cured by an energy ray, having excellent adhesion to a transparent film, and having a hard coat property, in order to have a high hard coat property,
A monomer having a plurality of (meth) acryloyl groups is used as a reactive compound. In addition to the monomer, another reactive compound is used to improve curl and adhesion, and photopolymerization is started in the case of an ultraviolet curable type. Those containing an agent are preferred. Examples of the monomer having a plurality of (meth) acryloyl groups include dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexa (meth) acrylate, hexa (meth) acrylate obtained by reacting dipentaerythritol with epsilon-caprolactone, Examples include pentaerythritol triacrylate, ethylene glycol di (meth) acrylate, and the like.

The reactive compound other than the monomer having a plurality of (meth) acryloyl groups includes, for example, a reactive monomer other than the monomer and a reactive oligomer.
Examples of the reactive monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, tetrahydrofurfuryl acrylate, glycidyl (meth) acrylate, acryloylmorpholine, t-butylaminoethyl (meth) acrylate, -Cyano (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylacrylamide, N-vinylpyrrolidone, N-vinyl-ε-caprolactam, phenoxydiethylene glycol (meth) acrylate and the like. As the reactive oligomer, for example, polyester (meth) acrylate obtained by reacting polyester polyol with (meth) acrylic acid, bisphenol-type epoxy resin and (meth) acrylate or hydroxy (meth) acrylate
Epoxy (meth) acrylate obtained by reaction with acrylate, reaction of organic polyisocyanate with hydroxy (meth) acrylate compound, or polyol with organic polyisocyanate and hydroxy (meth)
Urethane (meth) acrylate obtained by reaction with an acrylate compound, and the like.

Examples of the photopolymerization initiator include 1-hydroxycyclohexylphenylketone, (1-6-η-cumene) (η-cyclopentadienyl) iron (1+) hexafluorophosphoric acid (1-), , 2-Dimethoxy-2-phenylacetophenone, Michler's ketone, 2-methyl- [4
-(Methylthio) phenyl] -2-morpholino-1-
Propanone, 2-benzyl-2-dimethylamino-1-
(4-morpholinophenyl) -butanone-1,2-chlorothioxanthone, 2,4-dimethylthioxanthone,
Examples thereof include 2,4-diisopropylthioxanthone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide. These photopolymerization initiators can be used alone or as a mixture of two or more kinds in an arbitrary ratio.

In order to impart high hard coat properties, the amount of the monomer having a large number of (meth) acryloyl groups in the energy ray-curable resin composition is 40% by weight or more, preferably 50 to 90% by weight. And other reactive compounds are contained in an amount of not more than 60% by weight, preferably about 10 to 50% by weight. In the case of an ultraviolet-curable resin composition, the photopolymerization initiator is added in an amount of preferably 0.01 to 10 parts by weight, and more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the composition.

Further, various leveling agents may be used for imparting abrasion resistance and antifouling property to the layer having fine irregularities formed on the surface having uniformity when coated on a transparent film. it can. Examples of such a material include a silicone-based or fluorine-based varnish, a surfactant, and a coupling agent.

It is also possible to add various solvent-dried resins to the above-mentioned energy ray-curable resin composition. By adding a solvent-drying resin, a non-glare sheet having high transmission image sharpness can be produced, and thus it is preferably used. Solvent-dried resin is a solid that is solid at room temperature and soluble in a solvent. Examples of such a compound include a polyester resin, a polyurethane resin, a fluororesin, a cellulose resin, a polyolefin resin, and an acrylic resin. , A polycarbonate resin, an acrylate resin and the like, preferably a cellulosic resin, more preferably ethyl cellulose and hydroxypropyl cellulose. The amount of addition is 0.01 to 50 parts by weight, more preferably 0.1 to 40 parts by weight, even more preferably about 0.5 to 30 parts by weight based on 100 parts by weight of the energy ray-curable resin composition. Good.

In the interference fringe eliminating sheet of the present invention, an anti-reflection layer is further formed on the cured film layer as an anti-reflection layer, for example, by laminating a large number of low refractive index fluorine resin layers or thin films of silicon dioxide or a metal compound. It is also possible to form layers. By providing the above antireflection layer optically designed to reduce the reflected light by the light interference effect on the cured film layer, the light scattered on the cured film layer surface can be reduced and the transmitted light can be increased. it can. Therefore, when used for a display or the like, a clearer and easier-to-view display screen is obtained, which is preferable. The thickness of the antireflection film layer and the number of layers of the multilayer antireflection film are appropriately determined depending on the refractive index of the material used.

In the interference fringe eliminating sheet of the present invention, examples of the transparent film include plastic and the like, but the total light transmittance is preferably 80% or more, more preferably, in order not to lower the visibility of the image display device. 90%
Above is good. As the plastic, a thermoplastic resin, a thermosetting resin, an energy ray-curable resin such as ultraviolet light, etc. can be used.For example, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, triacetyl cellulose, butyl cellulose and the like can be used. Examples include cellulose resin, polystyrene, polyurethane, vinyl chloride, acrylic resin, polycarbonate resin, and acrylate resin. When used for an image display device, a transparent plastic that is optically homogeneous and isotropic is preferable, and examples of such a plastic include plastics such as polyester resin, cellulose resin, acrylic resin, and polycarbonate. . The thickness of the film is preferably 25 to 300 μm, more preferably 50 to 200 μm, from the viewpoint of weight reduction.

Further, in order to enhance the adhesiveness between the energy ray-curable resin composition and the film, it is possible to apply various treatments to the surface of the film. Examples of the treatment method include a primer treatment and a corona treatment. Examples of the resin for forming the primer layer include a polyester resin, a polyurethane resin, and an acrylic ether polyol resin. Its thickness is 0.
It is from 0.05 to 1.0 μm, preferably from 0.1 to 0.3 μm.

In the present invention, a cured film layer is formed on a transparent film to produce an interference fringe eliminating sheet as follows. That is, an energy ray-curable resin composition (a photopolymerization initiator is added in the case of an ultraviolet-curable type) and fine particles are uniformly dissolved or dispersed in a solvent, and a mixture adjusted to a desired concentration is dispersed. The solution can be obtained by applying a liquid on the film so as to have a uniform thickness, removing the solvent preferably by heating, and then irradiating an energy ray to cure the mixture. As the solvent, there is no particular limitation as long as the energy ray-curable resin composition dissolves without destroying the dispersion state of the fine particles, for example, toluene, methanol, ethanol, alcohols such as isopropyl alcohol, acetone, ketones such as methyl ethyl ketone, Esters such as ethyl acetate and butyl acetate are exemplified. These solvents may be used alone or in a mixture at an arbitrary ratio. The method for applying the dispersion of the mixture is not particularly limited, but is preferably a uniform film thickness in order to keep the characteristics of the non-glare layer constant. For example, a wire bar method, a dip coating method, a spin coating method, a gravure method Various coating methods such as a method, a microgravure method, and a doctor blade method can be used.
Suitable energy rays are preferably 2000 Å to 7 Å obtained from a high-pressure mercury lamp, a low-pressure mercury lamp, a xenon lamp, a germicidal lamp, a laser beam or the like.
Electromagnetic wave energy (for example, ultraviolet light) having a wavelength of 000 angstroms or high energy rays such as electron beams, X-rays, and radiations are used. The irradiation time of the energy ray depends on the intensity of the energy ray, but usually about 0.1 second to 10 seconds is sufficient.

The thickness of the sheet has the desired light scattering property, clearness of transmitted image, and hard coat property, and further eliminates interference fringes caused by shrinkage of the energy ray-curable resin composition upon curing. In order to reduce curl, the average thickness of the cured film is preferably 1.5 to 7 μm,
More preferably, it is about 2 to 5 μm.

The thus obtained interference fringe eliminating sheet is bonded to an acrylic plate, a glass plate, a plastic film or the like using a (pressure-sensitive) adhesive to obtain a plate-like article or a laminate. If desired, the plate-shaped article or laminate has an antistatic function to prevent contamination by static electricity, an electromagnetic wave shielding function to cut electromagnetic waves, an infrared cut function to prevent malfunctions of remote controls, etc., and reduces reflection of external light. It is also possible to provide an anti-glare function, an anti-reflection function, etc.

The thus obtained interference fringe eliminating sheet, plate-like article or laminate is applied to an image display device such as a touch panel, a plasma display or a reflection type liquid crystal display device so that the cured film layer is on the image display surface side. The image display device of the present invention can be obtained by arranging the sheet in front of the image display surface, preferably by arranging the sheet so as to be in contact with the display surface without being bonded. The method of arranging the interference fringe elimination sheet of the present invention is not particularly limited. And fixing using a magic tape or the like.

The image display device thus obtained can prevent the occurrence of interference fringes caused by a thin layer of air generated between the image display surface and the interference fringe eliminating sheet, plate-like article or laminate on the front surface. Can be improved.

[0023]

The present invention will now be described more specifically with reference to practical examples and comparative examples. Example 1 1.7 parts by weight of silica fine particles having an average secondary particle diameter of 1.0 μm, 5 parts by weight of a photopolymerization initiator (Irgacure 184: manufactured by Ciba Geigy), 90 parts by weight of dipentaerythritol hexaacrylate, 2- 100 parts by weight of an ultraviolet-curable acrylic resin containing 10 parts by weight of hydroxyethyl acrylate was stirred at high speed in a mixed solvent of toluene and isopropyl alcohol, and a mixed dispersion was prepared so as to have a solid content of 40% by weight. A 50 μm-thick double-sided easily-adhesive treated PET film (A43, manufactured by Toyobo Co., Ltd.)
00) was applied by microgravure coating, the solvent was evaporated, and then cured by irradiating light with a high-pressure mercury lamp of 80 W / cm to form a cured film layer having a thickness of 2.
An interference fringe eliminating sheet of the present invention having fine irregularities of 5 μm was obtained. Next, the back surface of this film was bonded to an acrylic plate using a pressure-sensitive adhesive to obtain an interference fringe eliminating plate. Table 1 shows the evaluation results of this plate. Furthermore, this interference fringe eliminating plate,
With the layer having fine irregularities inside, the image display surface is arranged so as to be in contact with the front surface of the image display surface of the liquid crystal display device without being bonded, and the presence or absence of interference fringes and the visibility of the display image are visually observed. As a result, no interference fringes occurred, the displayed image was clear, and the visibility was good.

Example 2 0.17 parts by weight of fine silica particles having an average secondary particle diameter of 1.8 μm was used, and fine irregularities were obtained by the same operation as in Example 1 except that the thickness of the cured film layer was 4 μm. An interference fringe eliminating sheet of the present invention was obtained. This sheet was evaluated in the same manner as in Example 1. The results are shown in Table 1. Further, when the presence or absence of interference fringes and the visibility of the displayed image were visually evaluated using a liquid crystal display device as in Example 1, no interference fringes were generated, and the displayed image was clear and had good visibility. Met.

Comparative Example 1 An acrylic plate having fine irregularities (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Acryfilter MR-2NG T70) was evaluated in the same manner as in Example 1. The results are shown in Table 1.
Further, when the presence or absence of interference fringes and the visibility of a display image were visually evaluated using a liquid crystal display device in the same manner as in Example 1, no interference fringes were generated, but the display image flickered and sharpness was observed. , Visibility was poor.

Comparative Example 2 A sheet having a cured film of an ultraviolet curable resin composition was obtained in the same manner as in Example 1 except that no silica fine particles were used. Evaluation was performed in the same manner as in Example 1 using this sheet. The results are shown in Table 1. Further, this sheet was used in Example 1.
When the presence or absence of interference fringes and the visibility of the displayed image were visually evaluated using a liquid crystal display device in the same manner as described above, the displayed image was clear, but interference fringes were generated and the visibility of the displayed image was poor. Met.

[0027]

[Table 1]

(1) Light scattering: Haze value was measured using a haze meter (manufactured by Tokyo Denshoku Co., Ltd.). (2) Transmission image clarity: A method similar to JIS K7105 image clarity measuring method was used to measure the distance between the test piece and the lens on the light receiving unit side by using an image clarity measuring device (manufactured by Suga Test Instruments Co., Ltd.).
0 cm), optical comb width 0.05 mm, 2.0 mm
Of the transmitted image was measured.

From the results shown in Table 1, it can be seen that the transmission image of the sheet of the present invention is clearer than that of the comparative example.

[0031]

According to the present invention, there is provided a transparent film having a layer having fine irregularities formed of a cured film of an energy ray-curable resin composition containing fine particles, and having a haze value of 1 to 5.
%, And a fine unevenness having a transmitted image clarity of 40% or more at an optical comb width of 0.05 mm, comprising: a protective plate for a plasma display; In such a case, the occurrence of interference fringes can be prevented, and a display screen that is easier to see can be obtained.

Claims (7)

[Claims] An interference fringe eliminating sheet comprising a transparent film and a layer having fine irregularities formed of a cured film of an energy ray-curable resin composition containing fine particles, wherein the haze of the interference fringe eliminating sheet is provided. An interference fringe eliminating sheet having a value of 1 to 5% and a transmitted image definition of 40% or more at an optical comb width of 0.05 mm in an image clarity measuring device. 2. The interference fringe eliminating sheet according to claim 1, wherein the transmitted image clarity at an optical comb width of 2.0 mm is 80% or more. 3. The interference fringe eliminating sheet according to claim 1, wherein a fluorine resin layer or a multilayer antireflection film is formed on a surface of the layer having irregularities. 4. An interference fringe eliminating sheet comprising a transparent film provided with a layer having fine irregularities formed of a cured film of an energy ray-curable resin composition containing fine particles, wherein the haze of the interference fringe eliminating sheet is provided. A sheet having a value of 1 to 5% and a transmitted image clarity of 40% or more at an optical comb width of 0.05 mm in the image clarity measuring device is arranged in front of the display surface with the layer having fine irregularities inside. Image display device. 5. The image display device according to claim 4, wherein the sheet is in contact with the display surface without being bonded. 6. The image display device according to claim 4, wherein the image display device is a plasma display or a liquid crystal display device. 7. The image display device according to claim 4, wherein the image display device is a touch panel.