JP5303242B2 - Antireflection film - Google Patents

Description

  The present invention relates to an antireflection film, and more particularly to an antireflection film having excellent antireflection performance.

In recent years, development of high-definition and large-screen displays typified by liquid crystal display devices (LCDs) and plasma display panels (PDPs) has been progressing rapidly. In order to improve the visibility of the display surface of the display, it is necessary to dispose an antireflection film having an antireflection function on the surface in order to prevent reflection of external light such as a fluorescent lamp on the screen.
Such an antireflection film is provided with a low refractive index layer on at least the outermost surface and performs antireflection by optical interference. In order to achieve a higher antireflection function, for example, a configuration in which two layers of a high refractive index layer and a low refractive index layer are provided, or three layers of a medium refractive index layer, a high refractive index layer, and a low refractive index layer are provided. There has been proposed an antireflection film that exhibits antireflection performance due to optical interference caused by a plurality of layers, including the structure to be provided (Patent Document 1, etc.).
As a method for producing an antireflection film, an inorganic metal is vapor-deposited or sputtered on the display surface, a so-called dry coating method or a low refractive index material is applied to a substrate in a liquid form such as a solution or a dispersion, dried, and then necessary. There is known a wet coating method or the like that is produced by curing in response. With the recent increase in the size of displays, a wet coating method that is inexpensive and easy to cope with an increase in size using Roll-to-Roll is becoming mainstream.
In the antireflection film by the wet coating method, various devices have been conventionally made in order to achieve higher antireflection performance. For example, the use of a fluorine-containing material as the low refractive index layer (Patent Document 2, etc.) and the optimization of the layer structure of the antireflection layer (Patent Document 3, etc.) have been proposed. Thus, conventionally, attention has been paid only to the surface on which the antireflection layer is provided, and the material and the layer structure have been improved.

Japanese Patent Laid-Open No. 10-300902 JP 2004-354740 A JP 2005-275225 A

  However, in order to cope with the demand for higher antireflection performance associated with higher quality of antireflection films in recent years and the mass production accompanying the increase in demand, the conventional technology has been limited and cannot be supported. is there.

  This invention is made | formed in order to solve the said subject, and it aims at providing the antireflection film which has a higher antireflection function.

The object of the present invention is achieved by an antireflection film having the following constitution.
(1) The reflectance with respect to the back coat layer surface of the base film formed by forming a back coat layer on one surface of the translucent substrate shows a minimum value at a wavelength of 530 nm to 580 nm, and the minimum reflectivity An antireflection film having a value of 0.5% to 4.0% and further comprising an antireflection layer on the other side of the base film on which the backcoat layer is formed.
(2) The antireflective film as described in (1) whose refractive index of a backcoat layer is 1.3-1.6 and is lower than the refractive index of a translucent base material.
(3) The antireflection film according to any one of (1) to (2), wherein an optical film thickness of the backcoat layer is 130 nm to 150 nm.

ADVANTAGE OF THE INVENTION According to this invention, the low visibility sensitivity reduction of an antireflection film can be achieved, and it becomes possible to provide the antireflection film which has higher antireflection performance.

In the antireflection film of the present invention, a back coat layer is formed on one surface of a translucent substrate, the reflectivity with respect to the back coat layer surface shows a minimum value at a wavelength of 530 nm to 580 nm, and the minimum value of the reflectivity is 0.00. By using the base film of 5% to 4.0%, it is possible to achieve a low visibility reflectance of the antireflection film and to exhibit higher antireflection performance. Moreover, it is preferable that the refractive index of the said backcoat layer is 1.3-1.6 and is lower than the refractive index of the said translucent base material. And it is more preferable that the optical film thickness of a backcoat layer is 130 nm-150 nm.
Here, the minimum value of the reflectance refers to the smallest value of the reflectance when the reflection spectrum is measured. Moreover, what is necessary is just to show the minimum value of the reflectance with respect to a backcoat layer surface in the wavelength range of 530 nm-580 nm. When the minimum value of the reflectance with respect to the back coat layer surface is indicated by a wavelength smaller than the wavelength of 530 nm or a wavelength larger than the wavelength of 580 nm, the value of the visibility reflectance of the antireflection layer becomes high. On the other hand, when the minimum value of the reflectance with respect to the back coat layer surface is larger than 4.0%, the visibility reflectance value of the antireflection layer becomes high.
In the present invention, the reflectance with respect to the back coat layer surface means that the other surface of the base film with respect to the back coat layer surface is roughened with, for example, a file and further coated with black ink or the like. This refers to the measurement of the reflection of only the back coat layer surface without the influence of the reflection from the other surface on the coat layer surface.
On the other hand, in the present invention, the reflectance with respect to the antireflection layer surface means that the backcoat layer surface of the antireflection film is bonded to a substrate such as glass with an adhesive or the like, and the antireflection film of the substrate is bonded. This refers to the measurement of reflection with the effect of reflection from the other surface on the antireflection layer surface, with black tape or the like attached to the non-reflection surface.
In the present invention, the optical film thickness means an n × d value obtained by multiplying the physical film thickness d and the refractive index n of each layer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing a layer configuration of an embodiment of an antireflection film according to the present invention.
The antireflection film 10 of the present embodiment includes a base film 13 formed by forming a back coat layer 11 on a translucent base 12 and a surface of the base film 13 on which the back coat layer 11 is formed. The antireflection layer 14 formed on the surface is provided.
<Base film>
The base film 13 constituting the antireflection film 10 of the present invention is formed by forming a back coat layer 11 on a translucent base 12.

  Moreover, the reflectance with respect to the backcoat layer surface of the base film 13 shows a minimum value at a wavelength of 530 nm to 580 nm, and the minimum value of the reflectance is 0.5% to 4.0%.

By adjusting the refractive index and thickness of the back coat layer 11 and the translucent base material 12 constituting the base film 13, the minimum value of the reflectance of the base film 13 with respect to the back coat layer 11 is set to the wavelength. In the range of 530 nm to 580 nm, the content may be 0.5% to 4.0%.
<Translucent substrate>
The translucent base material 12 constituting the antireflection film 10 of the present invention is not particularly limited as long as it is formed of a translucent material. For example, polyester resin, polycarbonate resin, polyacrylate resin, alicyclic polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyvinyl acetate resin, polyethersulfone resin, triacetyl cellulose What processed materials, such as resin, in the shape of a film or a sheet can be used. Of these, polyester resins are preferred from the standpoint of economics and thermal and mechanical form stability that can withstand even when applied to the front of the display. The polyester resin used for the translucent substrate 12 is not particularly limited, and a known polyester resin can be used. Examples thereof include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate. Among these, polyethylene terephthalate is preferably used from the viewpoint of cost and mechanical strength.
Examples of methods for processing the translucent substrate 12 into a film or sheet include extrusion molding, calendar molding, compression molding, injection molding, and a method in which the above resin is dissolved in a solvent and cast. Additives such as antioxidants, flame retardants, heat resistance inhibitors, ultraviolet absorbers, lubricants and antistatic agents may be added to the above materials.
The thickness of the translucent substrate 12 is preferably 10 μm to 500 μm, and more preferably 50 μm to 200 μm. When the thickness of the translucent substrate 12 is too thin, the handling property becomes poor. On the other hand, when the thickness of the translucent substrate 12 is too thick, there is not only a problem in terms of cost, but also when the film is wound and stored in a roll shape, poor flatness due to curling tends to occur. Coat layer>
The back coat layer 11 constituting the antireflection film 10 of the present invention is formed on the translucent substrate 12.
The refractive index of the backcoat layer 11 is lower than the refractive index of the translucent substrate 12, and is preferably 1.3 to 1.6.

  Moreover, it is preferable that the optical film thickness of the backcoat layer 11 is 130 nm-150 nm.

  Note that the back coat layer 11 has not only an optical function but also a function of improving adhesion with other media such as a functional film and a glass substrate, and an easy-sliding function.

The back coat layer 11 preferably contains any one of a polyester resin, a polyurethane resin, and an acrylic resin.
The polyester resin is a general term for polymers having an ester bond in the main chain. The polyester resin is generally obtained by a reaction between a polycarboxylic acid and a polyol. As the polycarboxylic acid, for example, fumaric acid, adipic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, or the like can be used. Among these, terephthalic acid and naphthalenedicarboxylic acid can be preferably used. What copolymerized sodium sulfoisophthalate etc. is preferable since it can be used as a water-soluble or water-dispersible polyester resin.

  Examples of the polyol include ethylene glycol, propylene glycol, 1,4 butanediol, 1,6 hexanediol, glycerin, hexanetriol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyester polyol. Can do.

  The polyurethane resin is a general term for polymers having a urethane bond in the main chain. A polyurethane resin is generally obtained by a reaction of a polyisocyanate and a polyol. Examples of the polyisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and naphthalene diisocyanate. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, and hexane. Triol or the like can be used.

An acrylic resin is a general term for polymers having acrylic acid, methacrylic acid and derivatives thereof as components. As the acrylic resin, for example, a polymer obtained by copolymerizing a monomer copolymerizable with acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylonitrile, hydroxyl acrylate or the like as a main component. Can be used.
The back coat layer 11 has a silica, titanium oxide, calcium carbonate, calcium silicate, barium sulfate, calcium phosphate, aluminum oxide, magnesium oxide, zirconium oxide, cerium oxide, tin oxide, indium oxide for adjusting the refractive index. , Etc. may contain inorganic fine particles or crosslinked polymer fine particles. The average particle diameter of the fine particles is 0.01 μm to 1.0 μm, preferably 0.01 μm to 0.5 μm. When the average particle size exceeds 1.0 μm, the film surface becomes rough, and the transparency of the film tends to be lowered or the fine particles are liable to fall off. When the average particle size is less than 0.01 μm, dispersion becomes difficult. .
Two or more kinds of the above fine particles may be blended in the back coat layer 11, or the same kind of particles having different diameters may be blended. In any case, it is preferable that the average particle diameter of the entire fine particles satisfies the above range.
Furthermore, it is preferable that the fine particles also serve as an easy slip function. That is, it is preferable to form appropriate protrusions on the surface of the backcoat layer 11 by causing some of the particles to protrude from the surface of the backcoat layer 11.

The method for forming the backcoat layer 11 on the translucent substrate 12 is not particularly limited, but a wet coating method is preferable from the viewpoint of productivity and production cost. As the wet coating method, a known method can be used. For example, a coating method such as roll coating, die coating, air knife coating, blade coating, reverse coating, gravure coating, or gravure printing, screen printing, offset printing, inkjet Printing methods such as printing can be used. Moreover, you may form the translucent base material 12 and the backcoat layer 11 simultaneously in-line. For example, when the translucent substrate 12 is a polyethylene terephthalate film, when the polyethylene terephthalate film is stretched or cast to form a film, a back coat layer can be simultaneously formed on the surface. This method is a widely known method, and a film-formed one can be easily obtained as a commercial product.
<Antireflection layer>
The antireflection layer 14 constituting the antireflection film 10 of the present invention is formed on the other surface of the base film 13 on which the backcoat layer 11 is formed.

The antireflection layer 14 is preferably composed of a plurality of layers. Although the configuration of the antireflection layer 14 is not particularly limited, for example, from the surface of the base film 13,
(1) Hard coat layer / low refractive index layer (2) Primer layer / hard coat layer / low refractive index layer (3) Hard coat layer / high refractive index layer / low refractive index layer (4) Primer layer / hard coat layer / High refractive index layer / Low refractive index layer (5) Hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layer (6) Primer layer / Hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layer.
The primer layer, hard coat layer, high refractive index layer, medium refractive index layer, and low refractive index layer have different layer structures to be designed depending on the properties required for the antireflection film, and the thickness and refractive index of each layer are the design layer structure. Set accordingly.
The refractive index of the primer layer is the same as that of the hard coat layer and the translucent substrate 12 formed on the primer layer, n _F ≦ n _P ≦ n _B, or n _F ≧ n _P ≧ n _B , and | n It is preferable to satisfy the relationship of _P −n _B | ≦ 0.1. Incidentally, the refractive index of the translucent substrate 12 n _B, the refractive index of the primer layer n _P, the refractive index of the hard coat layer and n _F. Further, the primer layer has a function of improving the adhesion and slipperiness between the base film 13 and the hard coat layer. If the above relationship can be satisfied, it may be formed of only a resin material, or may be formed of a mixed material of a resin material and a filler such as inorganic fine particles.
The resin may be the same as that of the back coat layer 11, or an ionizing radiation curable resin may be used when hardness is required.
In addition, the primer layer is provided with silica, titanium oxide, calcium carbonate, calcium silicate, barium sulfate, calcium phosphate, aluminum oxide, magnesium oxide, zirconium oxide, cerium oxide, tin oxide for adjusting the refractive index or imparting slipperiness. Inorganic oxides mainly composed of indium oxide, and crosslinked polymer fine particles may be contained. The average particle diameter of the fine particles is 0.01 μm to 1.0 μm, preferably 0.01 μm to 0.5 μm. If the average particle size exceeds 1.0 μm, the surface of the primer layer becomes rough, the transparency of the primer layer tends to decrease, and the particles tend to fall off. If the average particle size is less than 0.01 μm, dispersion is difficult. It becomes.
Moreover, it is preferable that the thickness of a primer layer is 80 nm-100 nm.
The method for forming the primer layer on the translucent substrate 12 is not particularly limited, but the wet coating method is preferable from the viewpoint of productivity and production cost. As the wet coating method, a known method can be used. For example, a coating method such as roll coating, die coating, air knife coating, blade coating, reverse coating, gravure coating, or gravure printing, screen printing, offset printing, inkjet Printing methods such as printing can be used. Moreover, you may form the translucent base material 12 and a primer layer into a film in-line simultaneously. For example, when the translucent substrate 12 is a polyethylene terephthalate film, a primer layer can be simultaneously formed on the surface of the polyethylene terephthalate film when it is stretched or cast. This method is a widely known method, and a film-formed one can be easily obtained as a commercial product.
The hard coat layer preferably has a refractive index of 1.51 to 1.75.
The required refractive index differs depending on the layer structure of the antireflection layer to be designed. For example, when the layer structure of the antireflection layer is primer layer / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index layer, the refractive index of the hard coat layer is 1.50 to 1.54. It is preferable that
If the refractive index of the hard coat layer falls within the above range, it may be formed of only a resin material or a mixed material of a resin material and a filler such as inorganic fine particles. Examples of the inorganic fine particles include silica, titanium oxide, calcium carbonate, calcium silicate, barium sulfate, calcium phosphate, aluminum oxide, magnesium oxide, zirconium oxide, cerium oxide and the like.
Moreover, it is preferable that the thickness of a hard-coat layer is 900 nm-5000 nm.

  As the resin used for the hard coat layer, an ionizing radiation curable resin having a particularly high surface hardness is preferable. As the ionizing radiation curable resin, monomers, prepolymers, oligomers, polymers, and the like having vinyl groups, (meth) acryloyl groups, epoxy groups, oxetanyl groups, thiol groups, and the like are used. The above resins can be used alone or in combination of two or more. In addition, it is preferable to use a polyfunctional resin as the resin from the viewpoint of the productivity of the hard coat layer and the hardness after curing, and it has many bonding groups and functional groups that form hydrogen bonds in the molecule. When it does, since adhesiveness with a translucent base material improves, it is preferable. Further, a high refractive index type resin such as bisphenol A-modified (meth) acrylate may be used.

  Examples of the polyfunctional resin include polyfunctional acrylic resin monomers having two or more unsaturated groups such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1 , 4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, Dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetrimethacrylate; pentaerythritol Polyurethane polyacrylates such as reacrylate hexamethylene diisocyanate urethane prepolymer; esters formed from polyhydric alcohols such as polyester polyacrylate and (meth) acrylic acid, 1,4-divinylbenzene, 4-vinylbenzoic acid-2 -Vinylbenzene, such as acryloyl ethyl ester and 1, 4- divinylcyclohexanone, and derivatives thereof. These may be used alone or in combination of two or more. Among these, it is preferable to contain at least one selected from pentaerythritol triacrylate and dipentaerythritol hexaacrylate from the viewpoint of further improving scratch resistance. In the above, “(meth) acrylate” means “acrylate and / or methacrylate”.

  When curing the ionizing radiation curable resin contained in the hard coat layer, in the case of performing ultraviolet irradiation, a photopolymerization initiator is added to the coating liquid for the hard coat layer. As photopolymerization initiators, acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, thiuram compounds, fluoroamine compounds Etc. are used. These can be used alone or in combination of two or more. Although the usage-amount of a photoinitiator is not specifically limited, It is 1 to 15 weight% with respect to the weight of the ionizing-radiation-curable resin monomer to be used.

As other components constituting the hard coat layer, additives such as a polymerization inhibitor, an antioxidant, a dispersant, a surfactant, a light stabilizer and a leveling agent may be appropriately added to such an extent that the refractive index is not greatly changed. Good. Further, any amount of solvent can be added as long as the film is dried by the wet coating method. As long as the ionizing radiation curable resin can be dissolved without breaking the dispersion system, a known organic solvent can be appropriately selected and used.
The low refractive index layer preferably has a refractive index of 1.35 to 1.45.
As a material for adjusting the refractive index of the low refractive index layer to a preferable range, silica, fluororesin, hollow silica particles, and the like can be considered. Among these, hollow silica particles are preferably used from the viewpoint of the refractive index and the scratch resistance of the antireflection layer.
The thickness of the low refractive index layer is preferably 90 nm to 110 nm.
The low refractive index layer may be formed using, for example, an ionizing radiation curable resin such as a monomer, a prepolymer, an oligomer, or a polymer having a vinyl group, a (meth) acryloyl group, an epoxy group, an oxetanyl group, or a thiol group. it can. The above resins can be used alone or in combination of two or more. Moreover, as said resin, it is preferable to use a polyfunctional resin from a viewpoint of the productivity of a low refractive index layer, and the hardness after hardening. As said polyfunctional resin, the thing similar to the polyfunctional acrylic resin monomer which has two or more unsaturated groups used for the above-mentioned hard-coat layer can be used.
When curing the ionizing radiation curable resin contained in the low refractive index layer, in the case of performing ultraviolet irradiation, the photopolymerization initiator used in the hard coat layer described above is similarly used in the coating solution for the low refractive index layer. Can be added.
Additives such as a polymerization inhibitor, an antioxidant, a dispersant, a surfactant, a light stabilizer and a leveling agent may be added to the low refractive index layer to such an extent that the refractive index is not greatly changed. Further, in order to improve the strength and antifouling property, a silicone-based or fluorine-based additive may be added to such an extent that the refractive index is not significantly changed. Further, any amount of solvent can be added as long as the film is dried by the wet coating method. If it is possible to dissolve the ionizing radiation curable resin without breaking the dispersion system, it is also possible to include a solvent in the coating solution for forming the low refractive index layer. As the solvent, a known organic solvent can be appropriately selected and used.
The high refractive index layer preferably has a refractive index of 1.60 to 1.95.
Since the required refractive index varies depending on the layer structure of the antireflection layer to be designed, for example, the layer structure of the antireflection layer is changed to primer layer / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index. When forming a layer, the refractive index of the high refractive index layer is preferably 1.75 to 1.95.
In order to adjust the refractive index of the high refractive index layer to a preferable range, it is preferable to include inorganic fine particles. Examples of the inorganic fine particles include silica, titanium oxide, calcium carbonate, calcium silicate, barium sulfate, calcium phosphate, aluminum oxide, magnesium oxide, zirconium oxide, cerium oxide and the like. Among these, titanium oxide is preferable, and it is particularly preferable to use titanium oxide fine particles having a rutile structure having a weak photocatalytic action and a high refractive index. For example, titanium oxide fine particles having an anatase structure have a photocatalytic action, and there is a possibility that organic substances such as a resin component and a substrate constituting this layer may be decomposed by irradiation with ultraviolet rays. The inorganic fine particles can be used alone or in combination of two or more.
The thickness of the high refractive index layer is preferably 70 nm to 170 nm.
Since the required layer thickness differs depending on the layer structure of the antireflection layer to be designed, for example, the layer structure of the antireflection layer is changed to primer layer / hard coat layer / medium refractive index layer / high refractive index layer / low. When the refractive index layer is used, the thickness of the high refractive index layer is preferably 140 nm to 155 nm.
Other materials used for the high refractive index layer are not limited as long as the refractive index can be adjusted within the above range. For example, as in the hard coat layer described above, a polyfunctional group or a monofunctional group (meta ) An acrylate monomer or acrylate oligomer, a photopolymerization initiator, an organic solvent, an antioxidant, a light stabilizer and the like can be used.

The medium refractive index layer may be a layer having a lower refractive index than the high refractive index layer to be laminated and a higher refractive index than the low refractive index layer, and the configuration thereof is a material such as the hard coat layer or the high refractive index layer described above. Can be appropriately selected and used.
The thickness of the medium refractive index layer is preferably 80 nm to 95 nm, although there is a relationship with the refractive index of other layers and the medium refractive index layer.
The method of forming each layer constituting the antireflection layer 14 is not particularly limited, but a wet coating method is preferable from the viewpoint of productivity and production cost. As the wet coating method, a known method can be used. For example, a coating method such as roll coating, die coating, air knife coating, blade coating, reverse coating, gravure coating, or gravure printing, screen printing, offset printing, inkjet Printing methods such as printing can be used.

  The antireflection film 10 of the present invention is bonded to the display surface of various display devices such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display device (CRT). And the visibility of the display device can be improved.

Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to the following examples. In the following, “parts” means “parts by weight” unless otherwise specified.
The characteristics of the base film and antireflection film of each example were evaluated by the following methods.
<Layer thickness and refractive index>
Using a reflection spectral film thickness meter “FE-3000” (manufactured by Otsuka Electronics Co., Ltd.), the thickness and refractive index of each layer constituting the back coat layer and the antireflection film constituting the base film were measured.
<Reflectance to the back coat layer surface>
The surface of the base film on which the back coat layer is not formed is shaved with a sandpaper, and further painted black with a black oil-based felt pen, and then the spectral reflectance measuring device “MCPD-3000” (manufactured by Otsuka Electronics Co., Ltd.) The reflectance with respect to the back coat layer surface was measured in the wavelength range of 300 nm to 800 nm.
<Reflectance to the antireflection layer surface>
In the antireflection film, the surface on which the antireflection layer was not formed, that is, the surface on which the backcoat layer was formed, and a glass plate having a thickness of 2 mm were bonded with an adhesive to prepare a measurement sample. In the prepared sample, a black tape is pasted on the glass plate surface on which the antireflection film is not bonded, and a spectral reflectance measuring device “MCPD-3000” (manufactured by Otsuka Electronics Co., Ltd.) is used for a wavelength range of 300 nm to 800 nm. The reflectance with respect to the antireflection layer surface was measured. And the visibility reflectance in D65 light source was computed from the measured reflectance according to JIS-Z-8701.
<Total light transmittance>
The total light transmittance of the antireflection film was measured using a turbidimeter “NDH-2000” (manufactured by Nippon Denshoku Industries Co., Ltd.).
Example 1
As a base film, a silica-containing backcoat layer made of a polyester resin is formed on one surface, and an easy adhesion layer having a refractive index of 1.59 and a thickness of 87 nm is formed on the other surface. A polyethylene terephthalate film having a thickness of 100 μm and a refractive index of 1.66 was prepared. The back coat layer had a refractive index of 1.55, a thickness of 86 nm, and an optical film thickness of 133.3 nm. Moreover, as a result of measuring the reflectance of the surface on which the antireflection layer was not formed in the base film, the reflectance with respect to the so-called back coat layer surface, the minimum value of the reflectance was 3.1% at a wavelength of 550 nm.
Next, an antireflection layer was formed as described below on the other surface of the base film, which was the backcoat layer measured above, to obtain an antireflection film for evaluation.
First,
"DPHA-40H" (urethane acrylate oligomer, manufactured by Nippon Kayaku Co., Ltd.) 6.8 parts,
0.9 part of pentaerythritol triacrylate (PETA),
“IRGACURE907” (photopolymerization initiator, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.23 parts,
4.8 parts of methyl isobutyl ketone (MIBK),
And 27 parts of propylene glycol monomethyl ether (PGME) was mix | blended and the coating liquid was produced.
This coating solution was applied on a base film using a micro gravure coater (manufactured by Yasui Seiki Co., Ltd.) and then dried to obtain a coating film. Subsequently, the coating film was irradiated with ultraviolet rays at a dose of 500 mJ / cm ² and cured to form a hard coat layer having a thickness of 3.0 μm. The refractive index of the hard coat layer was 1.52.
next,
Dipentaerythritol hexaacrylate (DPHA) 0.33 parts,
"Selnax CX-Z210IP F2" (zinc antimonate dispersion, manufactured by Nissan Chemical Industries, Ltd.) 2.0 parts,
"IRGACURE907" (photopolymerization initiator, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.02 parts,
2.5 parts isopropyl alcohol (IPA),
5 parts of methyl isobutyl ketone (MIBK),
And 5 parts of propylene glycol monomethyl ether (PGME) was mix | blended, and the coating liquid was produced.
This coating solution was applied onto the hard coat layer formed above using a micro gravure coater (manufactured by Yasui Seiki Co., Ltd.) and then dried to obtain a coating film. Subsequently, the coating film was irradiated with ultraviolet rays at a dose of 500 mJ / cm ² and cured to form a medium refractive index layer having a thickness of 88 nm. The refractive index of the middle refractive index layer was 1.60.
next,
"TTO-51A" (titanium oxide fine particles, manufactured by Ishihara Sangyo Co., Ltd.) 10 parts,
“Disperbyk-180” (dispersant, manufactured by Big Chemie) 1.0 part,
After putting zirconia beads having a diameter of 0.3 mm as beads for stirring and dispersing into a container containing a composition in which 5.0 parts of acetylacetone and 51 parts of propylene glycol monomethyl ether (PGME) are mixed, the mixture is dispersed for 3 hours using a paint shaker. Then, zirconia beads were removed to prepare a dispersion.
And
2.5 parts of the dispersion prepared above, 0.12 parts dipentaerythritol hexaacrylate (DPHA),
"IRGACURE907" (photopolymerization initiator, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.01 part, isopropyl alcohol (IPA) 5.0 part,
Methyl isobutyl ketone (MIBK) 0.3 part and propylene glycol monomethyl ether (PGME) 4.3 part were blended to prepare a coating solution.
This coating solution was applied onto the medium refractive index layer formed above using a micro gravure coater (manufactured by Yasui Seiki Co., Ltd.) and then dried to obtain a coating film. Subsequently, the coating film was irradiated with ultraviolet rays at a dose of 500 mJ / cm ² and cured to form a high refractive index layer having a thickness of 147 nm. The refractive index of the high refractive index layer was 1.83.
Finally,
"ELCOM P-special product" (hollow silica fine particles, manufactured by JGC Catalysts & Chemicals Co., Ltd.) 2.7 parts,
Dipentaerythritol hexaacrylate (DPHA) 0.13 parts,
0.05 parts of hydroxypivalic acid neopentyl glycol diacrylate (HPNGDA),
0.26 part of pentaerythritol triacrylate (PETA),
“X-22-2445” (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.01 part “IRGACURE907” (photopolymerization initiator, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.02 part,
17.5 parts isopropyl alcohol (IPA),
9.8 parts of methyl isobutyl ketone (MIBK),
And 9.9 parts of propylene glycol monomethyl ether (PGME) was mix | blended and the coating liquid was produced.
This coating solution was applied onto the high refractive index layer formed above using a micro gravure coater (manufactured by Yasui Seiki Co., Ltd.) and then dried to obtain a coating film. Subsequently, the coating film was irradiated with ultraviolet rays at a dose of 500 mJ / cm ² and cured to form a low refractive index layer having a thickness of 100 nm. The refractive index of the low refractive index layer was 1.37. Thus, the evaluation antireflection film of Example 1 was produced.
(Comparative Example 1)
The base film has a refractive index of 1.59, a thickness of 83 nm, an optical thickness of 132.0 nm, and a minimum reflectance of 4.5% at a wavelength of 530 nm with respect to the surface of the backcoat layer. An antireflection film for evaluation of Comparative Example 1 was produced in the same manner as Example 1 except that the change was made.
(Comparative Example 2)
The base film was changed to one having a refractive index of the backcoat layer of 1.50, a thickness of 52 nm, an optical film thickness of 78 nm, and a minimum reflectance of 2.0% with respect to the backcoat layer surface at a wavelength of 300 nm. Except for the above, an antireflection film for evaluation of Comparative Example 2 was produced in the same manner as Example 1.
Table 1 shows the evaluation results of various characteristics.

As shown in Table 1, the antireflection film of Example 1 has an antireflection layer surface as compared with the antireflection films of Comparative Examples 1 and 2 whose reflectance to the backcoat layer surface does not belong to the specified range of the present invention. The luminous reflectance is as low as 0.1%, and the total light transmittance is as high as 1.0%. That is, it turns out that the antireflection film of Example 1 has higher antireflection performance.

It is a schematic diagram which shows an example of the laminated constitution of the antireflection film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Antireflection film 11 Backcoat layer 12 Translucent base material 13 Base film 14 Antireflection layer

Claims (3)

The reflectance with respect to the backcoat layer surface of the substrate film formed by forming a backcoat layer on one surface of the translucent substrate shows a minimum value at a wavelength of 530 nm to 580 nm, and the minimum value of the reflectance However, it is 0.5%-4.0%, Furthermore, the antireflection film which equips the other surface with the surface in which the backcoat layer was formed in the said base film. The antireflection film according to claim 1, wherein the back coat layer has a refractive index of 1.3 to 1.6 and is lower than the refractive index of the translucent substrate. The antireflection film according to claim 1, wherein the backcoat layer has an optical film thickness of 130 nm to 150 nm.

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