JP5168209B2 - Antireflection film - Google Patents

Description

  The present invention relates to an antireflection film, and more particularly to an antireflection film provided on a display surface in order to prevent reflection of light on a display surface of a display device such as a liquid crystal display device.

  On the display surface of a display device such as a liquid crystal display device, if the reflection of light emitted from an external light source such as an indoor fluorescent tube is large, the visibility and aesthetics of the display device may be impaired. For example, interference between light reflected from the surface of the display surface and light reflected from interfaces in a plurality of layers in the display device may cause unevenness due to interference fringes and impair visibility and aesthetics. Therefore, in order to improve the visibility and aesthetics of the display device, it has been conventionally performed to provide an antireflection film having a layer that reduces such reflection and interference on the display surface of the outermost layer of the display device. .

  As a layer for reducing reflection and interference in an antireflection film, a layer in which a plurality of low refractive index layers and high refractive index layers are alternately laminated on a base film is known. For example, Patent Document 1 describes an antireflection layer in which a plurality of low refractive index layers made of an inorganic compound and high refractive index layers made of an inorganic compound are alternately stacked. Thus, the antireflection layer in which a plurality of low refractive index layers and high refractive index layers are alternately laminated can achieve a reduction in reflectance more effectively than an antireflection layer comprising only one low refractive index layer.

  However, the antireflection layer in which a plurality of such low refractive index layers and high refractive index layers are alternately stacked has a complicated manufacturing process for stacking the plurality of layers, and thus the manufacturing process is complicated and the manufacturing cost is low. Is expensive.

  On the other hand, as a base film for the antireflection film, a multilayer film composed of a flexible layer, a hard layer, and a flexible layer is used so that the surface hardness of the antireflection film can be increased and wound as a roll. It is known to use. Such a multilayer film can be efficiently produced by coextrusion molding or the like. However, no attempt has been made in the past to use such a multilayer structure to optically exhibit an antireflection function.

JP 2007-256475 A

  An object of the present invention is to provide an antireflection film that has improved reflectance and hardness, improved hardness and adhesion, is easy to manufacture, and is low in manufacturing cost.

As a result of studies to solve the above problems, the present inventor adopted a specific multilayer film as the base film constituting the antireflection film, and one low refractive index layer and a plurality of layers of the base film As a result of optically cooperating, it was found that the same antireflection effect as that obtained by alternately laminating a plurality of low refractive index layers and high refractive index layers was obtained, and the present invention was completed.
That is, according to the present invention, the following [1] to [7] are provided.

[1] An antireflection film comprising a substrate film having a first surface and a second surface opposite to the first surface, and a low refractive index layer provided on the first surface of the substrate film Because
The base film includes a first layer located on the outermost layer on the first surface side of the base film, a second layer located on the second surface side from the first layer, and the second layer. A third layer located on the second surface side,
The refractive index of the first layer is higher than the refractive index of the low refractive index layer,
An antireflection film, wherein the refractive index of the second layer is lower than the refractive index of the first layer.
[2] The antireflection film according to [1], wherein the refractive index of the third layer is higher than the refractive index of the second layer.
[3] The first layer and the second layer contain a resin, and the resin constituting the first layer and the resin constituting the second layer contain the same polymerization unit,
The first layer further includes fine particles dispersed in the resin;
The antireflection film according to [1] or [2], wherein the fine particles have a refractive index higher than the resin of the first layer by 0.05 or more.
[4] The third layer includes a resin, and the resin constituting the third layer includes the same polymerization unit as the resin constituting the first layer and the second layer,
The antireflection film according to [3], wherein the refractive index of the second layer is 1.59 or less.
[5] The antireflection film according to any one of [1] to [4], which has a layer made of a material having a hydrophilic group as a layer located in the outermost layer of the second surface.
[6] The antireflection film according to any one of [1] to [5], wherein the refractive indexes of the first layer and the third layer are both 1.50 or more.
[7] The antireflection film according to any one of [1] to [6], wherein the reflectance of light incident on the low refractive index layer is 1.5% or less.

  Since the antireflection film of the present invention has a low reflectance and can be easily produced, it is useful as an antireflection film on display surfaces of various display devices such as liquid crystal display devices.

It is a longitudinal section showing an example of the antireflection film of the present invention roughly.

  The antireflection film of the present invention includes a base film having a first surface and a second surface opposite to the first surface, a low refractive index layer provided on the first surface of the base film, including. The base film includes a first layer located on the outermost layer on the first surface side of the base film, a second layer located on the second surface side of the first layer, and a second layer of the second layer. And a third layer located on the second surface side. Accordingly, the base film includes the first layer, the second layer, and the third layer in this order from the first surface side.

  FIG. 1 is a longitudinal sectional view schematically showing an example of the antireflection film of the present invention. In FIG. 1, the antireflection film 1 includes a base film 10 having a first surface 10A and a second surface 10B, and a low refractive index layer 21 provided on the base film first surface 10A. In this example, the base film 10 includes a first layer 11, a second layer 12, and a third layer 13, and the third layer 13 is located on the outermost layer of the second surface. On the surface 1A on the side where the low refractive index layer 21 is provided, the antireflection film 1 has an antireflection effect. That is, the reflectance of light incident on the surface 1A can be reduced.

(Base film)
Each of the first to third layers constituting the base film can be a layer containing a resin. Moreover, in addition to resin, arbitrary substances can further be included. Preferred examples of such an arbitrary substance include fine particles for adjusting the refractive index.

  As the resin constituting the first layer to the third layer, various transparent resins can be used. Such a transparent resin is a resin having a thickness of 1 mm and a total light transmittance of 80% or more. For example, resin having alicyclic structure, polyester resin, cellulose resin, polycarbonate resin, polysulfone resin, polyethersulfone resin, polystyrene resin, polyolefin resin, polyvinyl alcohol resin, polyvinyl chloride resin, polymethyl methacrylate resin, etc. It is done.

  Preferably, the resin constituting the first layer and the resin constituting the second layer can be a resin that is a polymer containing the same polymerization unit. More preferably, in addition to the resin constituting the first layer and the resin constituting the second layer, the resin constituting the third layer can also be a resin that is a polymer containing the same polymerized unit. By constituting each layer with a resin that is a polymer containing the same polymer unit, the adhesion of these interfaces can be made good, and the mechanical and optical properties should be uniform. As a result, an antireflection film having good optical properties and good mechanical properties such as durability can be obtained.

The fine particles that can be included in the first layer to the third layer in order to adjust the refractive indexes of the first layer to the third layer can be particles made of an organic material, an inorganic material, or a mixture thereof. Examples of the fine particles made of an organic material include styrene beads. Examples of the fine particles made of an inorganic material include fine particles made of Al ₂ O ₃ , Sb ₂ O ₅ , ZrO ₂ , TiO ₂ , or a mixture thereof. The number average particle diameter of the fine particles can be 5 to 300 nm. Many of these fine particles have a higher refractive index of the layer as the content ratio of the fine particles in the layer is higher. Therefore, the preferable refractive index of each layer can be obtained as the content ratio of the fine particles in each layer. It can be adjusted as appropriate.

  The first to third layers may contain an optional compounding agent in addition to the transparent resin and the fine particles. Although there is no special limitation as a compounding agent, stabilizers, such as antioxidant, a heat stabilizer, a light stabilizer, a weathering stabilizer, a ultraviolet absorber, a near-infrared absorber; Resin modifiers, such as a lubricant and a plasticizer Colorants such as dyes and pigments; antistatic agents and the like. These compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the object of the present invention, and is usually 0 to 100 parts by weight of the transparent resin. 5 parts by weight, preferably 0 to 3 parts by weight.

  As described later, the base film is preferably a high refractive index layer such as the first layer and optionally the third layer, preferably 1.50 or more, more preferably 1.55 or more. In order to obtain layers having such a high refractive index, these layers preferably contain fine particles having a high refractive index. Specifically, it is preferable to contain fine particles having a refractive index higher than that of the resin by 0.05 or more.

The hardness of each of the first layer, the second layer, and the third layer can be arbitrarily set, but the second layer is formed so that the antireflection film has a high surface hardness and can be wound as a roll. It is preferable that it is relatively hard and the first layer and the third layer are softer than the second layer. Specifically, the hardness of the second layer is preferably a Martens hardness of 180 N / mm ² or more, and the hardness of the first layer and the third layer is preferably less than a Martens hardness of 180 N / mm ² .

In addition to the first layer to the third layer, the base film can optionally have an arbitrary layer on the second surface side from the third layer. That is, the third layer may be the outermost layer on the second surface side of the base film, and the layer other than the third layer may be the outermost layer on the second surface side of the base film.
Examples of an arbitrary layer that can be provided on the second surface side from the third layer include a layer made of a material having a hydrophilic group.

  The base film may have an uneven structure on the first surface side. Such a concavo-convex structure can be provided by a known arbitrary process such as pressing an embossing roll against the first surface where the first layer is located in the manufacturing process of the base film. The base film may have the same component as the low refractive layer on the first surface side.

  Although the manufacturing method of a base film is not specifically limited, The method including the process of coextruding the material which comprises a 1st layer-3rd layer, and shape | molding a multilayer film is preferable. Although such a multilayer film can be used as it is as a base film in the present invention, if necessary, after forming the multilayer film, an optional layer is further formed on the second surface side as the outermost layer on the second surface side. It is also possible to obtain a base film having an arbitrary layer in addition to the first to third layers, and use it in the present invention.

  More specifically, the second surface is obtained by applying a material having a hydrophilic group to the second surface side of the multilayer film obtained by coextrusion molding to obtain a coating film and curing the coating film. It can be set as the base film which has a layer (henceforth a "hydrophilic layer" sometimes) which consists of material which has a hydrophilic group in the outermost layer of the side. Examples of the material having a hydrophilic group constituting the hydrophilic layer include, for example, an acrylic resin, silica, a modified silica coupling agent, and the like, and a layer that comes into contact with the antireflection film when the antireflection film is provided on the display device. (For example, it can be set as the material with favorable adhesiveness with the polyvinyl alcohol of a polarizer.).

(Low refractive index layer)
The low refractive index layer constituting the antireflection film of the present invention is obtained by applying a material for forming the low refractive index layer (low refractive index forming material) to the base film to obtain a coating film, and the coating film. Can be obtained by curing.
As a material for forming a low refractive index, any material having a low refractive index can be appropriately selected. Examples thereof include a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in the resin, and a sol-gel material using a metal alkoxide such as tetraethoxysilane. The material forming these low refractive index layers may be a polymerized polymer, or a monomer or oligomer that is a precursor of a certain polymer (that is, cured by polymerization at the stage of curing the coating film). Thing). Moreover, it is preferable that each material contains the compound containing a fluorine group, in order to provide antifouling property.

As the sol-gel material, a sol-gel material containing a fluorine group is preferably used. Examples of the sol-gel material containing a fluorine group include fluorine-containing alkylalkoxysilanes. The fluorine-containing alkylalkoxysilane is, for example, represented by the general formula (1): CF ₃ (CF ₂ ) nCH ₂ CH ₂ Si (OR) ₃ (wherein R represents an alkyl group having 1 to 5 carbon atoms, n Represents an integer of 0 to 12). Specifically, the fluorine-containing alkylalkoxysilane includes trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane. , And heptadecafluorodecyltriethoxysilane. Among these, the compound whose said n is 2-6 is preferable.

  The low refractive index layer can be made of a cured product of a thermosetting fluorine-containing compound or an ionizing radiation curable fluorine-containing compound. The cured product preferably has a dynamic friction coefficient of 0.03 to 0.15, and a contact angle with water of 90 to 120 degrees. Examples of the curable fluorine-containing compound include perfluoroalkyl group-containing silane compounds and the like, as well as fluorine-containing polymers having a crosslinkable functional group.

This fluorine-containing polymer having a crosslinkable functional group is obtained by copolymerizing a fluorine-containing monomer and a monomer having a crosslinkable functional group, or by copolymerizing a fluorine-containing monomer and a monomer having a functional group, and then polymer. It can be obtained by adding a compound having a crosslinkable functional group to the functional group therein.
Fluoroolefins such as fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole; biscoat 6FM (Osaka Organic) Chemical), M-2020 (manufactured by Daikin), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives, fully or partially fluorinated vinyl ethers, and the like.

  Monomers having a crosslinkable functional group or compounds having a crosslinkable functional group include monomers having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate; monomers having a carboxyl group such as acrylic acid and methacrylic acid; hydroxyalkyl acrylate and hydroxyalkyl Monomers having hydroxyl groups such as methacrylate, methylol acrylate, methylol methacrylate; monomers having vinyl groups such as allyl acrylate and allyl methacrylate; monomers having amino groups; monomers having sulfonic acid groups; etc .; hydroxyalkyl (meth) Examples include acrylate and allyl acrylate.

  As a material for forming the low refractive index layer, a material containing a sol in which fine particles such as silica, alumina, titania, zirconia, magnesium fluoride and the like are dispersed in an alcohol solvent is used because it can improve scratch resistance. Can do. From the viewpoint of antireflection properties, the fine particles preferably have a lower refractive index. Such fine particles may have voids, and silica hollow fine particles are particularly preferable. The number average particle diameter of the hollow fine particles is preferably 5 nm to 2,000 nm, and more preferably 20 nm to 100 nm. Here, the number average particle diameter is a number average particle diameter obtained by observation with a transmission electron microscope.

  In the case of a low refractive index layer made of a cured product of a fluorine-containing compound, the scratch resistance of the low refractive index layer tends to decrease when the refractive index of the cured product is lowered. By optimizing the amount of addition, it is possible to achieve both scratch resistance and a low refractive index.

  The method for forming the coating film of the low refractive index layer material is not particularly limited, but the wet coating method is preferable because it is a simpler method than the vacuum deposition method or the like. Examples of the wet coating method include dip coating, air knife coating, curtain coating, roller coating, wire bar coating, and gravure coating. The thickness of the low refractive index layer is preferably about 0.05 μm to 0.3 μm, particularly preferably 0.065 μm to 0.20 μm.

  As another method for forming the low refractive index layer, a method by vapor deposition may be employed. In this case, examples of the material constituting the low refractive index layer include magnesium fluoride and silica.

(Refractive index of each layer)
In the antireflection film of the present invention, the refractive index of the first layer of the base film is higher than the refractive index of the low refractive index layer, and the second layer of the base film is higher than the refractive index of the first layer of the base film. The refractive index of is low. By having such a refractive index difference, the base film interacts optically in addition to the low refractive index layer, and as a result, even if only one low refractive index layer is formed, a high antireflection effect is achieved. It becomes possible to play.

  Furthermore, the refractive index of the third layer is preferably higher than the refractive index of the second layer. By having such a refractive index difference, a higher antireflection effect can be obtained.

The refractive index of the low refractive index layer is preferably 1.46 or less. The lower limit of the refractive index of the low refractive index layer is not particularly limited, but can be 1.2. The refractive index of the second layer is preferably 1.59 or less. The lower limit of the refractive index of the second layer is not particularly limited, but can be 1.47.
On the other hand, the refractive index of the first layer is preferably 1.50 or more. The refractive index of the third layer is preferably 1.50 or more. The upper limit of the refractive index of the first layer and the third layer is not particularly limited, but can be 1.70.

  The refractive index difference between the low refractive index layer and the first layer is preferably 0.04 to 0.5. The difference in refractive index between the first layer and the second layer is preferably 0.01 to 0.21. The refractive index difference between the second layer and the third layer is preferably 0.01 to 0.21.

(Thickness of each layer)
In the present invention, the preferred thickness of the low refractive index layer can be determined according to the center wavelength of the wavelength band in which reflection is required to be suppressed among the light incident on the low refractive index layer. Specifically, the thickness is preferably 1 / (4 × refractive index of the low refractive layer) of the center wavelength of the wavelength band in which reflection is required to be suppressed. For example, when the reflection in the visible region is suppressed, when the refractive index of the low refractive layer is 1.37, the thickness is about 100 nm which is 1 / (4 × 1.37) of 550 nm which is the central wavelength in the visible region. Preferably there is.

  On the other hand, the thickness of each layer from the first layer to the third layer can be arbitrarily determined within a range where the reflected light at each interface can contribute to interference. Moreover, it can adjust suitably according to desired requirements, such as mechanical strength as a base film, and a softness | flexibility. Specifically, each of the first to third layers can be in the range of 5 to 60 μm.

(Use)
The antireflection film of the present invention can have a low reflectance of light incident on the low refractive index layer. Specifically, the reflectance of light incident on the low refractive index layer (light incident on the surface 1A in the example of FIG. 1) can be set to a low value of 1.5% or less. Here, the reflectance is measured by measuring the reflectance at an incident angle of 5 ° at a wavelength of 430 to 700 nm using a spectrophotometer (ultraviolet visible near infrared photometer V-550, manufactured by JASCO Corporation) (measurement). The wavelength interval is 1 nm), which can be the minimum value when the reflectance in the wavelength region is measured.

  The use of the antireflection film of the present invention is not particularly limited, but the display surface of a display device such as a liquid crystal display device, a plasma display device, an electroluminescence display device, a cathode tube display device, a field emission display device, electronic paper, a touch panel, etc. It can be preferably used as a member.

  The antireflection film of the present invention can also be used by being affixed to these display devices, and these materials can be used to replace members such as a polarizing plate protective film and a front plate located in the outermost layer of a conventional display device. It can also be used in a display device. In any case, by providing the antireflection film of the present invention so that the low refractive index layer side becomes the viewing side, the reflection on the display surface is reduced, the reflection and interference on the display surface are prevented, and the visibility of the display device And aesthetics can be improved.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example. In the following, “parts” and “%” relating to the quantity ratio of the components represent parts by weight unless otherwise specified.

<Example 1>
(1-1: Material for forming the first layer)
100 parts of an acrylic resin (Sumitomo Chemical Industries Sumipex HT55X, refractive index 1.49), and 10 parts of silica (AEROSIL 130, number average particle diameter 16 nm, refractive index 1.46, manufactured by Evonik Dezaza Japan) as fine particles and zirconia (Ci Kasei) 20 parts of a product having a number average particle diameter of 30 nm and a refractive index of 1.70 were dry blended for 1 hour to prepare a first layer forming material.

(1-2: Second layer forming material)
Acrylic resin (Delpet TM, refractive index 1.49 manufactured by Asahi Kasei Chemical) was used.

(1-3: third layer forming material)
100 parts of an acrylic resin (Sumitomo Chemical Industries Sumipex HT55X, refractive index 1.49), and 10 parts of silica (AEROSIL 130, number average particle diameter 16 nm, refractive index 1.46, manufactured by Evonik Dezaza Japan) as fine particles and zirconia (Ci Kasei) 20 parts of a product having a number average particle size of 30 nm and a refractive index of 1.70 were dry blended for 1 hour to prepare a third layer forming material.

(1-4: Multilayer film molding)
Using a three-type three-layer multilayer coextrusion apparatus, the first layer forming material obtained in (1-1) above, the second layer forming material obtained in (1-2) above, and the above (1) The material for forming the third layer obtained in -3) was discharged from a T-die at extrusion rates of 10 kg / hr, 20 kg / hr, and 10 kg / hr, respectively. Thereafter, the laminate was cooled to obtain a multilayer film.
The thickness of each layer of the obtained multilayer film was the first layer 20 μm, the second layer 40 μm, and the third layer 20 μm, and the total thickness was 80 μm. The refractive indexes of the first to third layers are shown in Table 1.

(1-5. Preparation of Composition 1 for Forming Low Refractive Index Layer)
An ethanol solution of oxalic acid was prepared by adding 200 parts of ethanol to a four-necked reaction flask equipped with a reflux tube and adding 120 parts of oxalic acid to the ethanol in small portions while stirring. The solution was then heated to the reflux temperature, and a mixture of 20 parts tetraethoxysilane and 4 parts tridecafluorooctyltrimethoxysilane (GE Toshiba Silicone, trade name “TSL8257”) was added dropwise to the refluxed solution. did. After completion of the dropwise addition, heating was continued for 5 hours under reflux, followed by cooling and dilution with methanol so that the solid content was 1% by weight, thereby preparing Liquid 1.
Next, hollow silica fine particles (number average particle diameter 30 nm, refractive index 1.29) were added so as to be 30 parts by weight with respect to the solid content of the liquid 1 to prepare a composition 1 for forming a low refractive index layer. . The low refractive index layer was 90% of the silicon oxide component when dried and formed into a film. The refractive index of the low refractive index layer was 1.37.

(1-6: Formation of low refractive index layer, preparation of antireflection film)
The low refractive index layer composition obtained in (1-5) above was applied to the first surface (the surface on the first layer side) of the multilayer film obtained in (1-4) above using a bar coater, The coating film is cured at 70 ° C. for 1 minute at 100 ° C. to form a low refractive index layer having a thickness of 100 nm, and consists of four layers of low refractive index layer-first layer-second layer-third layer. An antireflection film of the present invention was obtained.

(1-7: Evaluation reflectance)
The reflectance of the surface on the low refractive index layer side of the antireflection film obtained in (1-6) above was measured. Using a spectrophotometer (ultraviolet visible near-infrared photometer V-550, manufactured by JASCO Corporation), the reflectance at an incident angle of 5 ° at a wavelength of 430 to 700 nm was measured (measurement wavelength interval was 1 nm), and The minimum reflectance in the wavelength region was measured. The results are shown in Table 1.

(1-8: Evaluation pencil hardness)
Except for changing the load to 500 g, according to JIS K 5600-5-4, the pencil was scratched by about 5 mm with 5 pencils on the surface of the antireflective film on the low refractive layer side, and the degree of damage was confirmed. The results are shown in Table 1.

(1-9: Evaluation adhesion)
The antireflection film obtained in (1-6) was cut in the length direction of 300 mm, and the corona discharge treatment was performed on the surface in the air with a discharge amount of 100 W / m ² · min. Film (A) "). The wetting tension on the surface of the film (A) subjected to the corona discharge treatment was 70 mN / m or more. A 10% aqueous solution of a polyvinyl alcohol polymer (manufactured by Kuraray Co., Ltd .: PVA203, degree of saponification of 86.5-89.5%, average degree of polymerization of 300) is dropped on the surface of the film (A) that has been subjected to corona treatment, On top of that, unstained polyvinyl alcohol biaxially stretched film (C) of the same size (polarization film: Boblon # 140 (film thickness: 14 μm) manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was bonded. Next, one surface of a film (B) (moisture permeability of 270 g / cm ² · 24 h) made of triacetyl cellulose having the same size as the film (A) and a thickness of 80 μm is saponified with a 10% aqueous solution of caustic soda. Then, a 10% aqueous solution of the same polyvinyl alcohol polymer was dropped. Next, the laminated film obtained by bonding the polarizing film (C) and the film (A) and the film (B) were bonded so that the aqueous solution application surface and the polarizing film side surface face each other. The above three-layer laminated film was placed in a roll laminator and pressed before the aqueous polyvinyl alcohol solution was dried. Next, the laminated film was allowed to stand at 40 ° C. for 72 hours to adhere each layer. The thickness of the adhesive layer was 1 μm. About the obtained laminated | multilayer film, the JISK5600 crosscut test was done and adhesiveness was confirmed. The results are shown in Table 1.

<Example 2>
Examples except that the acrylic resin used in (1-1), (1-2) and (1-3) was changed to a resin ZEONOR1420 having an alicyclic structure (refractive index 1.53 manufactured by Nippon Zeon Co., Ltd.) In the same procedure as 1, an antireflection film was prepared and evaluated. The results are shown in Table 1.

<Example 3>
(1-4) In the same procedure as in Example 1 except that the coextrusion conditions were changed and the thickness of each layer was changed to 10 μm for the first layer, 40 μm for the second layer, and 10 μm for the third layer. An antireflection film was prepared and evaluated. The results are shown in Table 1.

<Example 4>
80 parts of polyester resin (Mitsui Chemicals J125S refractive index 1.65), acrylic resin (Sumitomo Chemical Industries Sumipex HT55X, refractive index 1.49) 20 parts, silica fine particles 10 parts and zirconia fine particles 20 parts are dry blended for 1 hour. A mixture was prepared. The same silica fine particles and zirconia fine particles as those used in Example 1 were used.
An antireflection film was produced and evaluated in the same procedure as in Example 1 except that this mixture was used instead of the materials for forming the first layer and the third layer in (1-1) and (1-3). The results are shown in Table 1.

<Comparative Example 1>
An acrylic resin (Delpet TM manufactured by Asahi Kasei Chemical Co., Ltd., refractive index: 1.49) was used alone, and was discharged from a T-type die at an extrusion rate of 20 kg / hr using a single layer extrusion apparatus. Then, it cooled and obtained the single layer film.
The thickness of the obtained single layer film was 80 μm. An antireflection film was prepared and evaluated in the same procedure as in (1-5) and after in Example 1 except that this film was used instead of the multilayer film obtained in (1-4). The results are shown in Table 1.

<Comparative example 2>
A resin having an alicyclic structure (ZEONOR 1420, refractive index 1.53, manufactured by Nippon Zeon Co., Ltd.) was used alone and discharged from a T-type die at an extrusion rate of 20 kg / hr using a single-layer extrusion apparatus. Then, it cooled and obtained the single layer film.
The thickness of the obtained single layer film was 80 μm. An antireflection film was prepared and evaluated in the same procedure as in (1-5) and after in Example 1 except that this film was used instead of the multilayer film obtained in (1-4). The results are shown in Table 1.

<Comparative Example 3>
As the first layer forming material, an acrylic resin (Sumipex HT55X, refractive index 1.49, manufactured by Sumitomo Chemical Co., Ltd.) was used alone. As a material for forming the second layer, a mixture was prepared by dry blending 100 parts of an acrylic resin (Sumitomo Chemical Industries Sumipex HT55X, refractive index 1.49) and 12 parts of zirconia fine particles for 1 hour. As a material for forming the third layer, a mixture was prepared by dry blending 100 parts of an acrylic resin (Sumitomo Chemical Industries Sumipex HT55X, refractive index 1.49) and 30 parts of zirconia fine particles for 1 hour. The same zirconia fine particles as those used in Example 1 were used.
Antireflection was carried out in the same procedure as in Example 1 except that these first layer forming material to third layer forming material were used instead of the materials obtained in (1-1) to (1-3). Films were made and evaluated. The results are shown in Table 1.

1: Antireflection film 1A: Surface 10: Base film 10A: First surface 10B: Second surface 11: First layer 12: Second layer 13: Third layer

Claims (7)

An antireflection film comprising: a base film having a first surface and a second surface opposite to the first surface; and a low refractive index layer provided on the first surface of the base film. ,
The base film includes a first layer located on the outermost layer on the first surface side of the base film, a second layer located on the second surface side from the first layer, and the second layer. A third layer located on the second surface side,
The refractive index of the first layer is higher than the refractive index of the low refractive index layer,
Than the refractive index of the first layer, the refractive index of the second layer is rather low,
The first layer, the second layer, and the third layer contain a resin, and the resin that constitutes the first layer, the resin that constitutes the second layer, and the resin that constitutes the third layer Comprising the same polymerized unit, an antireflection film.   The antireflection film according to claim 1, wherein the refractive index of the third layer is higher than the refractive index of the second layer. Before Symbol first layer further comprises dispersed fine particles in the resin,
The antireflection film according to claim 1 or 2, wherein the fine particles have a refractive index higher by 0.05 or more than the resin of the first layer. Refractive index of the previous SL second layer is 1.59 or less, the antireflection film of claim 3.   The antireflection film according to any one of claims 1 to 4, wherein the antireflection film has a layer made of a material having a hydrophilic group as a layer located on the outermost layer of the second surface.   The antireflection film according to any one of claims 1 to 5, wherein both the first layer and the third layer have a refractive index of 1.50 or more.   The antireflection film according to any one of claims 1 to 6, wherein a reflectance of light incident on the low refractive index layer is 1.5% or less.

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