JP2006030544A - Antireflection film, polarizer and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which has improved adhesiveness between a low refractive index layer and a high refractive index layer just under the same and has improved scratch resistance as well as satisfactory optical characteristic. <P>SOLUTION: The antireflection film comprises a transparent substrate, a high refractive index layer which is formed directly or via other layer on the transparent substrate and comprises a composition for high refractive index layer formation including an ionizing radiation curable resin (A) and a low refractive index layer which is formed directly on the high refractive index layer and comprises a composition for low refractive index layer formation including an ionizing radiation curable resin (B). Therein, the high refractive index layer has irregularities on the surface of the side on which the low refractive index layer side is disposed, surface roughness of the irregularities is 1 to 10 nm and the ratio of the amount A of surface double bond before curing to the amount B of remaining surface double bond on the high refractive index layer is 0.3≤B/A≤0.9. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antireflection film, a polarizing plate using it as at least one surface of a surface protective film, and an image display device using the same.

  Antireflection films are used in various image display devices such as liquid crystal display devices (LCD), plasma display panels (PDP), electroluminescence displays (ELD), and cathode ray tube display devices (CRT) to reflect external light and In order to prevent a decrease in contrast due to reflection, it is arranged on the surface of the display.

  As an antireflection layer (a high refractive index layer, a medium refractive index layer, a low refractive index layer, etc.) used for an antireflection film, a multilayer film obtained by laminating a transparent thin film of metal oxide has been widely used. Usually, a transparent thin film of a metal oxide has been formed by a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, particularly a vacuum vapor deposition method or a sputtering method which is a kind of physical vapor deposition method.

  On the other hand, it is also possible to produce the antireflection film by wet coating. In this case, a coating composition prepared by dissolving or dispersing a composition for forming a film having a specific refractive index in a solvent is applied on a substrate, dried, and cured as necessary. A single-layer or multilayer thin film is formed. In the case of a single layer, the low refractive index layer may be formed with an optical film thickness of ¼ of the design wavelength. When further low reflection is required, a high refractive index layer may be formed between the base material and the layer having a low refractive index (see, for example, Patent Documents 1 and 2). In order to reduce the reflection in a wider wavelength range, an intermediate refractive index layer may be formed between the base material and the high refractive index layer (see, for example, Patent Document 3).

Such an antireflection film is often used on the outermost surface of a display. As the low refractive index layer material disposed on the outermost layer, a material having a low refractive index is desired from the viewpoint of antireflection performance, and at the same time, high physical strength is required.
In order to achieve high scratch resistance in a thin film with a thickness of around 100 nm, it is important to enhance the adhesion with the lower layer of the low refractive index layer, that is, the high refractive index layer, in addition to the strength of the low refractive index layer itself. It is.
In the wet coating method, various curable resins such as heat or photo-curable resin are sequentially applied and cured. In this case, in order to improve interlayer adhesion, a curable resin that forms an upper layer (low refractive index layer) in a half-cured state after coating a curable resin that forms a lower layer (high refractive index layer). A method is proposed in which the upper layer and the lower layer are cured after coating (see, for example, Patent Document 4).
However, even this method has a problem that the adhesion between the upper layer and the lower layer may be insufficient. In addition, when the upper layer is applied again, the interface between the upper layer and the lower layer is mixed, the surface condition is deteriorated, and desired optical characteristics may not be obtained.
On the other hand, a technique for improving the adhesion with the lower layer due to the anchor effect by forming irregularities on the surface of the lower layer has also been proposed (see, for example, Patent Document 5). There was also a problem that optical characteristics could not be obtained.
JP-A-8-110401 JP-A-11-153703 JP 2002-156508 A JP 2003-311911 A Japanese Patent Laid-Open No. 2002-311204

  The present invention provides an antireflection film having a low refractive index layer and a high refractive index layer, which improves the adhesion between the low refractive index layer and the high refractive index layer immediately below the antireflective film, and maintains good optical properties while being scratch resistant. Is to provide an improved antireflection film. Moreover, it is providing the antireflection film which has the said effect using this antireflection film, a polarizing plate, and a liquid crystal display device.

As a result of intensive studies to solve the above problems, the present inventors have determined that the roughness of the surface irregularities of the high refractive index layer is within a specific range and the surface before curing the composition for forming the high refractive index layer. In order to complete the present invention, it has been found that the above object can be achieved by controlling the amount of double bonds and the amount of residual double bonds after curing to form a high refractive index layer within a specific range. It came.
That is, according to the present invention, an antireflection film, a polarizing plate, an image display device and a liquid crystal display device having the following constitution are provided, and the above object of the present invention is achieved.
1. A high refractive index layer comprising a transparent substrate, a composition for forming a high refractive index layer containing the ionizing radiation curable resin (A), which is formed directly or via another layer on the transparent substrate, and the high refractive index layer An antireflective film having a low refractive index layer formed of a composition for forming a low refractive index layer containing an ionizing radiation curable resin (B) provided directly on the refractive index layer,
The high refractive index layer has irregularities on the surface where the low refractive index layer side is provided, the surface roughness of the irregularities is 1 to 10 nm, and the high refractive index layer has a surface double before curing. An antireflection film, wherein the ratio of the amount of bond A to the amount of residual surface double bond B after curing is 0.3 ≦ B / A ≦ 0.9.
2. 2. The antireflection film according to 1, wherein the surface irregularities of the high refractive index layer are derived from the shape of the inorganic fine particles.
3. 3. The antireflection film according to 2, wherein the inorganic fine particles have a particle size of 10 to 100 nm.
4). 4. The antireflection film as described in 2 or 3, wherein the content of the inorganic fine particles in the high refractive index layer is 50% by mass or more.
5. 5. The antireflection film as described in 4, wherein the inorganic fine particles are fine particles mainly composed of titanium dioxide.
6). 6. The antireflection film as described in any one of 1 to 5, wherein the haze is 1.0% or less.
7). The ratio of the surface double bond amount A before curing and the residual surface double bond amount B after curing in the high refractive index layer is 0.3 ≦ B / A ≦ 0.9. The antireflection film according to any one of 1 to 6.
7). The ratio of the surface double bond amount A before curing and the residual surface double bond amount B after curing in the high refractive index layer is 0.3 ≦ B / A ≦ 0.6. The antireflection film according to any one of 1 to 6.
8). The composition for forming a low refractive index layer contains a fluorine polymer represented by the following general formula (1) in an amount of 20% by mass or more based on the total solid content of the composition for forming a low refractive index layer. The antireflection film according to any one of the above.

L represents a linking group having 1 to 10 carbon atoms, and X represents a hydrogen atom or a methyl group. x, y, and z represent mol% of each constituent component, and 30 ≦ x ≦ 60, 5 ≦ y ≦ 70, and 0 ≦ z ≦ 65.
9. The antireflective film according to any one of 1 to 8, wherein the low refractive index layer contains 30% by mass or more of hollow silica.
10. A high refractive index layer-forming composition containing an ionizing radiation curable resin (A) is applied on a transparent substrate directly or via another layer and cured to have a surface roughness of 1 to 10 nm. A high refractive index layer forming step of forming a high refractive index layer;
A low-refractive-index layer forming step in which a low-refractive-index layer is formed by directly applying and curing a low-refractive-index layer-forming composition containing an ionizing radiation curable resin (B) on the high-refractive index layer; A method for producing an antireflection film containing
In the high refractive index layer forming step, the ratio of the surface double bond amount A before curing and the residual surface double bond amount B after curing of the high refractive index layer is 0.3 ≦ B / A ≦ 0. 9. A method for producing an antireflection film, comprising controlling the oxygen concentration and the irradiation amount during curing so as to be 9.
11. In the high refractive index layer forming step, the amount of surface double bonds A of the applied composition for forming a high refractive index layer before curing and the residual surface double bond amount B of the high refractive index layer formed after curing 11. The method for producing an antireflection film according to 10, wherein the oxygen concentration and the irradiation amount at the time of curing the high refractive index layer are controlled so that the ratio is 0.3 ≦ B / A ≦ 0.6. .
12. 12. The method for producing an antireflection film according to 10 or 11, wherein the oxygen concentration at the time of curing is controlled to 0.5% or less.
13. The method for producing an antireflection film according to any one of 10 to 12, wherein an irradiation amount during the curing is controlled to 200 mJ / cm ² or less.
14 A polarizing plate, wherein the antireflection film according to any one of 1 to 9 is used as a protective film on at least one side.
15. An image display device comprising the antireflection film according to any one of 1 to 9.
16. 14. A TN, STN, VA, IPS, OCB, or ECB mode transmissive, reflective, or transflective liquid crystal display device having at least one polarizing plate according to 14.

  Since the antireflection film of the present invention is very excellent in adhesion between the low refractive index layer and the high refractive index layer directly therebelow, it has high scratch resistance. Moreover, since it is excellent also in antireflection performance, when used for a display, deterioration of visibility due to reflection of external light is prevented at a high level.

  The antireflection film of the present invention will be described in detail below. In the present specification, the description “numerical value A” to “numerical value B” represents the meaning of “numerical value A or more and numerical value B or less” when the numerical value represents a physical property value, a characteristic value, or the like. The description of “(meth) acryloyl” means “acryloyl or methacryloyl, or both”. The same applies to “(meth) acrylate”, “(meth) acrylic acid”, and “(meth) acrylamide”.

[Configuration of antireflection film]
First, a configuration example of the antireflection film of the present invention will be described.
The antireflection film of the present invention comprises a transparent substrate and a composition for forming a high refractive index layer containing an ionizing radiation curable resin (A) formed on the transparent substrate directly or via another layer. A high refractive index layer, and a low refractive index layer made of a composition for forming a low refractive index layer containing an ionizing radiation curable resin (B) provided directly on the high refractive index layer.
That is, it is sufficient if the antireflection layer has at least two layers of a high refractive index layer and a low refractive index layer, and the number of layers can be selected according to the purpose, but it is low in a wide wavelength region. In order to realize reflection, as described in “Characteristics and Optimal Design / Film Creation Technology of Antireflection Film” (published on February 5, 2002, p. 15-16), transparent Three layers of a medium refractive index layer, a high refractive index layer, and a low refractive index layer are laminated in order from the substrate side, and the optical film thickness of each layer, that is, the product of the refractive index and the film thickness is λ with respect to the design wavelength λ. / 4, λ / 4, λ / 4, or λ / 4, λ / 2, λ / 4 are preferable.

FIG. 1 shows a preferred configuration example of the antireflection film of the present invention. FIG. 1 is a cross-sectional view schematically showing a layer configuration of an embodiment of the antireflection film of the present invention and schematically showing an embodiment of a polarizing plate using the antireflection film of the present invention.
As shown in FIG. 1, the antireflection film of this embodiment comprises a transparent substrate 1, a hard coat layer 2 formed on the transparent substrate 1, a medium refractive index layer 3 formed on the hard coat layer, It consists of a high refractive index layer 4 formed on the medium refractive index layer 3 and a low refractive index layer 5 as the uppermost layer formed on the high refractive index layer 4. That is, in the present embodiment, the high refractive index layer 4 is provided on the transparent substrate 1 via the hard coat layer 2 and the medium refractive index layer 3.
The haze of the antireflection film is preferably 1.0% or less, and more preferably 0.6% or less.

Hereinafter, the layers constituting the antireflection film of the present invention will be described in detail.
[Transparent substrate]
A plastic film is preferably used as the transparent substrate. Examples of the plastic film include cellulose esters (eg, triacetyl cellulose, diacetyl cellulose, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, nitrocellulose) and polyolefins (eg, polypropylene, polyethylene, polymethylpentene). Acetylcellulose and polyolefin are preferable for use as polarizing plates because of their low retardation and high optical uniformity. Particularly, when an antireflection film and a polarizing plate are used in a liquid crystal display device, triacetylcellulose is preferably used.
As the triacetyl cellulose, those disclosed in the public technique publication technical report number 2001-1745 are preferably used.
The thickness of the transparent substrate is preferably 10 to 200 μm from the viewpoint of thickness and handling suitability, and more preferably 40 to 100 μm.

[High refractive index layer]
In FIG. 1, a hard coat layer is provided immediately above the transparent substrate, and a medium refractive index layer is provided immediately above the hard coat layer. For convenience of explanation, the high refractive index layer and the uppermost low refractive index layer are provided first. Then, the medium refractive index layer and the hard coat layer will be described.
The refractive index of the high refractive index layer in the antireflection film of the present invention is preferably 1.60 to 2.40, and more preferably 1.70 to 2.20. The haze of the high refractive index layer is preferably 3% or less. Further, the thickness of the high refractive index layer is preferably 50 to 200 nm, and more preferably 60 to 120 nm.

In the present invention, the high refractive index layer is composed of a composition for forming a high refractive index layer containing an ionizing radiation curable resin (A). The composition for forming a high refractive index layer includes the ionizing radiation curable resin (A), and further includes a composition in which inorganic fine particles having a high refractive index and a polymerization initiator are dispersed in the ionizing radiation curable resin (A). The product is preferably used.
A high refractive index layer excellent in scratch resistance and adhesion can be formed by polymerizing and curing with ionizing radiation after applying the composition for forming a high refractive index layer.

{Composition for forming a high refractive index layer}
(Ionizing radiation curable resin (A))
The composition for forming a high refractive index layer contains, as the ionizing radiation curable resin (A), a polymerizable compound having an ionizing radiation curable polyfunctional monomer or a polyfunctional oligomer functional group.
The ionizing radiation curable resin (A) is preferably a light, electron beam, or radiation polymerizable compound, and a compound having a photopolymerizable functional group is particularly preferable.
Examples of the photopolymerizable functional group include unsaturated polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group is preferable.

  Specific examples of the polymerizable compound having a photopolymerizable functional group include (meth) acrylic acid diesters of alkylene glycols such as neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, and propylene glycol di (meth) acrylate. (Meth) acrylic acid diesters of polyoxyalkylene glycols such as triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate; (Meth) acrylic acid diesters of polyhydric alcohols such as pentaerythritol di (meth) acrylate; 2,2-bis {4- (acryloxy-diethoxy) phenyl} propane, 2-2-bis {4- (a (Meth) acrylic acid diesters of ethylene oxide or propylene oxide adducts such as (acryloxy / polypropoxy) phenyl} propane; and the like.

  Furthermore, epoxy (meth) acrylates, urethane (meth) acrylates, and polyester (meth) acrylates are also preferably used. Of these, esters of polyhydric alcohol and (meth) acrylic acid are preferred. More preferably, a polyfunctional monomer having 3 or more (meth) acryloyl groups in one molecule is preferable. Specifically, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, 1,2,4-cyclohexanetetra (meth) acrylate, pentaglycerol triacrylate, pentaerythritol tetra (meth) acrylate, penta Erythritol tri (meth) acrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol triacrylate, tripentaerythritol hexatriacrylate, etc. Two or more types may be used in combination.

The composition for forming a high refractive index can contain a photopolymerization initiator used for the polymerization reaction of the ionizing radiation curable resin (A). As the photopolymerization initiator, a photoradical polymerization initiator and a photocationic polymerization initiator are preferable, and a photoradical polymerization initiator is particularly preferable.
Examples of the photo radical polymerization initiator include acetophenones, benzophenones, Michler's benzoylbenzoate, α-amyloxime ester, tetramethylthiuram monosulfide, and thioxanthones.
Commercially available radical photopolymerization initiators can also be used. For example, KAYACURE (DETX-S, BP-100, BDKM, CTX, BMS, 2-EAQ, ABQ, CPTX, EPD manufactured by Nippon Kayaku Co., Ltd. , ITX, QTX, BTC, MCA, etc.), Irgacure (651, 184, 500, 907, 369, 1173, 2959, 4265, 4263, etc.) manufactured by Ciba Geigy Japan, Esacure (KIP100F, KB1, manufactured by Sartomer) EB3, BP, X33, KT046, KT37, KIP150, TZT) and the like.
In particular, photocleavable photoradical polymerization initiators are preferred. The photocleavable photoradical polymerization initiator is described in the latest UV curing technology (P.159, issuer; Kazuhiro Takashiro, publisher; Technical Information Association, Inc., published in 1991).
Examples of commercially available photocleavable photoradical polymerization initiators include Irgacure (651, 184, 907) manufactured by Nippon Ciba-Geigy Co., Ltd.

It is preferable to use a photoinitiator in the range of 1-10 mass parts with respect to 100 mass parts of said ionizing radiation curable resins (A), More preferably, it is the range of 2-6 mass parts.
In addition to the photopolymerization initiator, a photosensitizer may be used. Specific examples of the photosensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, Michler's ketone and thioxanthone.
Examples of commercially available photosensitizers include KAYACURE (DMBI, EPA) manufactured by Nippon Kayaku Co., Ltd.

(Inorganic fine particles)
As the inorganic fine particles, oxides of metals (for example, aluminum, titanium, zirconium and antimony) are preferable. From the viewpoint of refractive index, fine particles of titanium dioxide are preferable, and inorganic fine particles mainly containing titanium dioxide are most preferable.
The average particle size of the inorganic fine particles is preferably 10 to 100 nm. More preferably, it is 20-90 nm, More preferably, it is 40-80 nm. If it is this range, a desired optical characteristic can be acquired and abrasion resistance can be provided, without raising the haze of a coating film and without protruding an inorganic fine particle to a low-refractive-index layer.
By containing at least one element selected from Co (cobalt), Al (aluminum) and Zr (zirconium) in inorganic fine particles mainly composed of titanium dioxide, the photocatalytic activity of titanium dioxide can be suppressed, This is preferable because the weather resistance of the high refractive index layer can be improved.
A particularly preferable element is Co (cobalt). It is also preferable to use two or more types in combination.

  The inorganic fine particles mainly composed of titanium dioxide in the present invention preferably have a refractive index of 1.90 to 2.80, more preferably 2.10 to 2.80, and 2.20 to 2.80. 80 is most preferred.

The particle diameter of the inorganic fine particles can be measured by a light scattering method or an electron micrograph. The specific surface area of the inorganic fine particles is preferably 10 to 400 m ² / g, more preferably from 20 to 200 m ² / g, and most preferably from 30 to 150 m ² / g.
The crystal structure of the inorganic fine particles containing titanium dioxide as the main component is preferably a rutile, rutile / anatase mixed crystal, anatase or amorphous structure, particularly preferably a rutile structure.

(Dispersant)
In the present invention, a dispersant can be used for dispersing the inorganic fine particles used in the high refractive index layer.
In the present invention, it is particularly preferable to use a dispersant having an anionic group for dispersing the inorganic fine particles.
As the anionic group, a group having an acidic proton such as a carboxyl group, a sulfonic acid group (and a sulfo group), a phosphoric acid group (and a phosphono group), or a sulfonamide group, or a salt thereof is effective. A sulfonic acid group, a phosphoric acid group and a salt thereof are preferable, and a carboxyl group and a phosphoric acid group are particularly preferable. The number of anionic groups contained in the dispersant per molecule may be one or more.
A plurality of anionic groups may be contained for the purpose of further improving the dispersibility of the inorganic fine particles. The average number is preferably 2 or more, more preferably 5 or more, and particularly preferably 10 or more. Moreover, the anionic group contained in a dispersing agent may contain multiple types in 1 molecule.

  The dispersant preferably further contains a crosslinkable or polymerizable functional group. Crosslinkable or polymerizable functional groups include ethylenically unsaturated groups (for example, (meth) acryloyl groups, allyl groups, styryl groups, vinyloxy groups, etc.) that can undergo addition reactions and polymerization reactions with radical species, and cationic polymerizable groups (epoxies). Groups, oxatanyl groups, vinyloxy groups, etc.), polycondensation reactive groups (hydrolyzable silyl groups, etc., N-methylol groups) and the like, and functional groups having an ethylenically unsaturated group are preferred.

That is, the dispersant used for dispersing the inorganic fine particles preferably has an anionic group and a crosslinkable or polymerizable functional group, and has the crosslinkable or polymerizable functional group in the side chain.
The mass average molecular weight (Mw) of the dispersant used for the inorganic fine particles is not particularly limited, but is preferably 1000 or more. The more preferable mass average molecular weight (Mw) of the dispersant is 2000 to 1000000, more preferably 5000 to 200000, and particularly preferably 10000 to 100000.

  The amount of the dispersant used relative to 100 parts by mass of the inorganic fine particles is preferably in the range of 1 to 50 parts by mass, more preferably in the range of 5 to 30 parts by mass, and most preferably 5 to 20 parts by mass. preferable. Two or more dispersants may be used in combination.

{High refractive index layer forming step}
The inorganic fine particles are preferably used in the formation of a high refractive index layer by being contained in the composition for forming a high refractive index layer in a dispersion state.
A dispersion of inorganic fine particles can be obtained by dispersing in a dispersion medium in the presence of the above-described dispersant.
As the dispersion medium, a liquid having a boiling point of 60 to 170 ° C. is preferably used. Examples of dispersion media include water, alcohols (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), esters (eg, methyl acetate, ethyl acetate, Propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg hexane, cyclohexane), halogenated hydrocarbons (eg methylene chloride, chloroform, carbon tetrachloride), aromatic Hydrocarbon (eg, benzene, toluene, xylene), amide (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ether (eg, diethyl ether, dioxane, tetrahydrofuran) ), Ether alcohols (e.g., 1-methoxy-2-propanol) are included. Of these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and butanol are preferred.
Particularly preferred dispersion media are methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

The inorganic fine particles are dispersed using a disperser. Examples of dispersers include sand grinder mills (eg, pinned bead mills), high speed impeller mills, pebble mills, roller mills, attritors and colloid mills. A sand grinder mill and a high-speed impeller mill are particularly preferred. Further, preliminary dispersion processing may be performed. Examples of the disperser used for the preliminary dispersion treatment include a ball mill, a three-roll mill, a kneader, and an extruder.
The inorganic fine particles are preferably refined in a dispersion medium to have a mass average diameter of 10 to 100 nm, and more preferably 20 to 90 nm.
By setting the inorganic fine particles within the above range, a high refractive index layer that has a small haze and does not impair transparency can be formed (the same applies to a medium refractive index layer described later), which is preferable.

  In the high refractive index layer used in the present invention, the above-mentioned polymerization initiator and photosensitizer are appropriately added to the ionizing radiation curable resin (A), and more preferably, the inorganic fine particles are dispersed in the dispersion medium as described above. The resulting dispersion is added to form a composition for forming a high refractive index layer, the composition for forming a high refractive index layer is applied onto a transparent substrate, and a crosslinking reaction between the ionizing radiation curable resin (A) and the dispersant or It is preferably formed by being cured by a polymerization reaction.

  In the high refractive index layer thus prepared, for example, the above preferred dispersant and an ionizing radiation-curable polyfunctional monomer or polyfunctional oligomer undergo a crosslinking or polymerization reaction, and the anionic group of the dispersant is contained in the layer. Will be incorporated. Furthermore, the high refractive index layer has a function in which the anionic group maintains the dispersion state of the inorganic fine particles, the crosslinked or polymerized structure imparts a film forming ability, and the inorganic fine particles are coated with the ionizing radiation curable resin. The physical strength, chemical resistance, and weather resistance of the high refractive index layer can be improved.

  In addition to the above components (inorganic fine particles, polymerization initiators, photosensitizers, etc.), the high refractive index layer includes resins, surfactants, antistatic agents, coupling agents, thickeners, anti-coloring agents, and coloring. Agents (pigments, dyes), antifoaming agents, leveling agents, flame retardants, ultraviolet absorbers, infrared absorbers, adhesion-imparting agents, polymerization inhibitors, antioxidants, surface modifiers, conductive metal particles, etc. It can also be added.

  The high refractive index layer of the present invention has a surface roughness of the high refractive index layer within a specific range, and the high refractive index layer has a surface double bond amount A before curing and a residual surface after curing. The ratio with the double bond amount B is in a specific range. With this configuration, the adhesion between the high refractive index layer and the low refractive index layer directly provided on the high refractive index layer can be remarkably increased, and good optical characteristics can be maintained.

(Surface roughness)
In the present invention, the surface roughness of the surface irregularities on the side where the low refractive index layer of the high refractive index layer is provided is 1 to 10 nm. If it is less than 1 nm, the effect of improving interlayer adhesion is poor. The surface roughness is preferably 2 nm or more, and more preferably 3 nm or more. On the other hand, if it exceeds 10 nm, the haze of the layer increases.
The surface roughness (Ra) can be measured with an atomic force microscope.

By setting the particle size of the inorganic fine particles added to the high refractive index layer to the range described above for (inorganic fine particles), the surface roughness can be controlled within the above range.
Further, the inorganic fine particles are preferably added so that the content in the high refractive index layer after formation is 50% or more in the total solid content, more preferably 50 to 80% by mass, and 60 to 70%. It is more preferable to add mass%.
If it is said range, the unevenness | corrugation which inorganic fine particles form is sufficient, and it is preferable also from a viewpoint of the intensity | strength of a film | membrane and a weather resistance.

  The uneven surface shape of the high refractive index layer is preferably derived from the shape of the inorganic fine particles. The surface irregularity shape can be controlled by the amount of inorganic fine particles added to the high refractive index layer, the particle diameter, and the film thickness of the high refractive index layer.

(Ratio of surface double bond amount A before curing and residual surface double bond amount B after curing)
In the present invention, the ratio of the surface double bond amount A before curing and the residual surface double bond amount B after curing in the high refractive index layer is 0.3 ≦ B / A ≦ 0.9. In other words, the ratio B / A is a double bond residual ratio on the surface of the high refractive index layer, and indicates that the closer to 0, the closer to complete curing. The present inventors have found that adhesion can be improved by leaving unreacted binding groups on the surface of the high refractive index layer in a specific range when the low refractive index layer is applied.
The residual ratio B / A is more preferably 0.3 ≦ B / A ≦ 0.6.
The amount of double bonds on the surface can be quantified by modifying the unsaturated bond with bromine and measuring the peak intensity with ESCA.
When the residual ratio B / A of the double bond is less than 0.3, the bonding site with the low refractive index layer is insufficient, and thus the scratch resistance becomes insufficient. Conversely, when B / A exceeds 0.9, interfacial mixing occurs at the interface between the high-refractive index layer and the low-refractive index layer, so that the surface state deteriorates.
Further, B / A is preferably 0.6 or less. By setting B / A to 0.6 or less, the change in the thickness of the high refractive index layer before and after the formation of the low refractive index layer can be 3 nm or less, which is preferable. That is, by setting B / A in the range of 0.6 or less, in order to obtain desired optical characteristics, it is necessary to design in consideration of the decrease in the thickness of the high refractive index layer before and after the formation of the low refractive index layer. This is preferable because it can also suppress a decrease in manufacturing robustness.
As described above, when the change in the film thickness of the high refractive index layer is large, in order to obtain desired optical characteristics, it is sufficient to design in consideration of the decrease in film thickness, but the manufacturing robustness is lowered. The decrease in film thickness is preferably 3 nm or less, and more preferably 2 nm or less.

  The amount of residual double bonds can be controlled by the oxygen concentration at the time of curing and the irradiation amount. This point will be described in detail in the column of the manufacturing method.

[Low refractive index layer]
The low refractive index layer is formed by applying a composition for forming a low refractive index layer containing an ionizing radiation curable resin (B) on the high refractive index layer, followed by curing polymerization. Examples of the ionizing radiation curable resin (B) include the polymerizable compounds exemplified in the ionizing radiation curable resin (A). Among them, a fluoropolymer having a repeating unit derived from a fluorine-containing vinyl monomer and a repeating unit having a (meth) acryloyl group in the side chain as essential constituent components is preferable from the viewpoint of refractive index and strength. The fluoropolymer preferably accounts for 20% by mass or more of the total solid content of the low refractive index layer, more preferably accounts for 40% by mass or more, and particularly preferably accounts for 80% by mass or more. From the viewpoint of achieving both low refractive index and film hardness, monomers such as polyfunctional (meth) acrylates are also preferably used in an addition amount within a range that does not impair the compatibility.

The refractive index of the low refractive index layer is preferably 1.20 to 1.50, more preferably 1.25 to 1.48, and particularly preferably 1.30 to 1.46.
The thickness of the low refractive index layer is preferably 50 to 200 nm, and more preferably 70 to 130 nm. The haze of the low refractive index layer is preferably 3% or less, more preferably 2% or less, and most preferably 1% or less. The specific strength of the low refractive index layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test under a 500 g load.
Further, in order to improve the antifouling performance of the antireflection film, it is preferable that the contact angle of the surface with respect to water is 90 ° or more. More preferably, it is 95 ° or more, and particularly preferably 100 ° or more.

{Fluoropolymer}
Next, the said fluoropolymer is demonstrated.
Examples of the fluorine-containing vinyl monomer that is a raw material component of the fluoropolymer include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, etc.), (meth) acrylic acid moieties or fully fluorinated alkyl ester derivatives (E.g., Biscoat 6FM (trade name, manufactured by Osaka Organic Chemical Co., Ltd.), M-2020 (trade name, manufactured by Daikin), etc.), fully or partially fluorinated vinyl ethers, and the like. Preferred are perfluoroolefins and refractive index. From the viewpoints of solubility, transparency, availability, etc., hexafluoropropylene is particularly preferable.
Increasing the composition ratio of these fluorine-containing vinyl monomers can lower the refractive index but lowers the film strength. In the present invention, the fluorine-containing vinyl monomer is preferably introduced so that the fluorine content of the fluoropolymer is 20 to 60% by mass, more preferably 25 to 55% by mass, and particularly preferably 30 to 50% by mass. %.

  The fluoropolymer used in the present invention preferably has a repeating unit having a (meth) acryloyl group in the side chain as an essential constituent component. If the composition ratio of these (meth) acryloyl group-containing repeating units is increased, the film strength is improved, but the refractive index is also increased. Generally, the (meth) acryloyl group-containing repeating unit preferably accounts for 5 to 90% by mass, more preferably 30 to 70% by mass in the fluoropolymer, although it varies depending on the type of repeating unit derived from the fluorine-containing vinyl monomer. It is particularly preferable to occupy 40 to 60% by mass.

  In the fluoropolymer useful in the present invention, in addition to the repeating unit derived from the above-mentioned fluorine-containing vinyl monomer and the repeating unit having a (meth) acryloyl group in the side chain, it contributes to adhesion to the substrate and Tg of the polymer (film hardness) And other vinyl monomers can be appropriately copolymerized from various viewpoints such as solubility in a solvent, transparency, slipperiness, dust resistance and antifouling properties. A plurality of these vinyl monomers may be combined depending on the purpose, and are preferably introduced in the range of 0 to 65 mol% in the copolymer in total, and more preferably in the range of 0 to 40 mol%. The range of 0 to 30 mol% is particularly preferable.

  The vinyl monomer unit that can be used in combination is not particularly limited. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid) 2-ethylhexyl, 2-hydroxyethyl acrylate), methacrylic acid esters (methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, etc.), styrene derivatives (styrene, p-hydroxymethylstyrene, p -Methoxystyrene, etc.), vinyl ethers (methyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, etc.), vinyl esters (vinyl acetate) Vinyl propionate, vinyl cinnamate, etc.), unsaturated carboxylic acids (acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, etc.), acrylamides (N, N-dimethylacrylamide, N-tertbutylacrylamide, N- Cyclohexylacrylamide), methacrylamides (N, N-dimethylmethacrylamide), acrylonitrile, and the like.

  As a preferred form of the fluoropolymer used in the present invention, the following general formula (1) may be mentioned.

In the general formula (1), L represents a linking group having 1 to 10 carbon atoms, more preferably a linking group having 1 to 6 carbon atoms, and particularly preferably a linking group having 2 to 4 carbon atoms, which is linear. Alternatively, it may have a branched structure, may have a ring structure, or may have a heteroatom selected from O, N, and S.
Preferred examples include *-(CH ₂ ) ₂ -O-**, *-(CH ₂ ) ₂ -NH-**, *-(CH ₂ ) ₄ -O-**, *-(CH ₂ ) ₆ -O-**, *-(CH ₂ ) ₂ -O- (CH ₂ ) ₂ -O-**, -CONH- (CH ₂ ) ₃ -O-**, * -CH ₂ CH (OH) CH ₂ -O- *, * -CH ₂ CH ₂ OCONH (CH ₂ ) ₃ -O-** (* represents the linking site on the polymer main chain side, and ** represents the linking site on the (meth) acryloyl group side. And the like). m represents 0 or 1;

  In general formula (1), X represents a hydrogen atom or a methyl group. From the viewpoint of curing reactivity, a hydrogen atom is more preferable.

  In the general formula (1), A represents a repeating unit derived from an arbitrary vinyl monomer, and is not particularly limited as long as it is a constituent component of a monomer copolymerizable with hexafluoropropylene. The polymer Tg (contributes to film hardness), solubility in solvents, transparency, slipperiness, dustproof / antifouling properties, etc., can be selected as appropriate, depending on the purpose. You may be comprised by the monomer.

  Preferred examples include methyl vinyl ether, ethyl vinyl ether, t-butyl vinyl ether, cyclohexyl vinyl ether, isopropyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, glycidyl vinyl ether, vinyl ethers such as allyl vinyl ether, vinyl acetate, vinyl propionate, butyric acid. (Meth) such as vinyl esters such as vinyl, methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth) acrylate, glycidyl methacrylate, allyl (meth) acrylate, (meth) acryloyloxypropyltrimethoxysilane Acrylates, styrene, styrene derivatives such as p-hydroxymethylstyrene, crotonic acid, maleic acid, itaconic acid Can be mentioned unsaturated carboxylic acids and derivatives thereof, more preferably ether derivatives, vinyl ester derivatives, particularly preferably a vinyl ether derivative.

  x, y, and z represent mol% of each constituent component, and represent values satisfying 30 ≦ x ≦ 60, 5 ≦ y ≦ 70, and 0 ≦ z ≦ 65. Preferably, 35 ≦ x ≦ 55, 30 ≦ y ≦ 60, and 0 ≦ z ≦ 20, and particularly preferably 40 ≦ x ≦ 55, 40 ≦ y ≦ 55, and 0 ≦ z ≦ 10. However, the sum of x, y, and z is 100.

  A particularly preferred form of the copolymer used in the present invention is general formula (2).

In the general formula (2), X, x, and y have the same meaning as in the general formula (1), and preferred ranges are also the same.
n represents an integer of 2 ≦ n ≦ 10, preferably 2 ≦ n ≦ 6, and particularly preferably 2 ≦ n ≦ 4.
B represents a repeating unit derived from an arbitrary vinyl monomer, and may be composed of a single composition or a plurality of compositions. As an example, what was demonstrated as an example of A in the said General formula (1) is applicable.
z1 and z2 represent mol% of each repeating unit, and represent values satisfying 0 ≦ z1 ≦ 65 and 0 ≦ z2 ≦ 65. It is preferable that 0 ≦ z1 ≦ 30 and 0 ≦ z2 ≦ 10 respectively, and it is particularly preferable that 0 ≦ z1 ≦ 10 and 0 ≦ z2 ≦ 5. However, the sum of x, y, z1, and z2 is 100.

  In the fluoropolymer represented by the general formula (1) or (2), for example, a (meth) acryloyl group is introduced into a copolymer comprising a hexafluoropropylene component and a hydroxyalkyl vinyl ether component by any one of the methods described above. Can be synthesized.

{Other compounds contained in low refractive index layer forming composition}
The low refractive index layer-forming composition used in the present invention is usually in the form of a liquid, and the ionizing radiation curable resin (B) is an essential constituent, and various additives and radical polymerization initiators are added as necessary. It is prepared by dissolving in an appropriate solvent. At this time, the concentration of the solid content is appropriately selected according to the use, but is generally about 0.01 to 60% by mass, preferably 0.5 to 50% by mass, particularly preferably 1% to 20% by mass. %.

  From the viewpoint of film hardness of the low refractive index layer, it is not always advantageous to add an additive such as a curing agent, but from the viewpoint of interfacial adhesion with the high refractive index layer, a polyfunctional (meth) acrylate compound, A curing agent such as a polyfunctional epoxy compound, polyisocyanate compound, aminoplast, polybasic acid or anhydride thereof, or a small amount of inorganic fine particles such as silica can be added. When these are added, it is preferably in the range of 0 to 30% by mass, more preferably in the range of 0 to 20% by mass, based on the total solid content of the composition for forming a low refractive index layer. It is especially preferable that it is in the range of -10 mass%.

  In addition, for the purpose of imparting properties such as antifouling properties, water resistance, chemical resistance, and slipping properties, known silicone-based or fluorine-based antifouling agents, slipping agents, and the like can be appropriately added. In the case of adding these additives, it is preferably added in the range of 0 to 20% by mass, more preferably in the range of 0 to 10% by mass of the total solid content of the composition for forming a low refractive index layer. Particularly preferably 0 to 5% by mass.

  The radical polymerization initiator may be in any form of generating radicals by the action of heat or generating radicals by the action of light.

As the compound that initiates radical polymerization by the action of heat, organic or inorganic peroxides, organic azo, diazo compounds, and the like can be used.
Specifically, benzoyl peroxide, halogen benzoyl peroxide, lauroyl peroxide, acetyl peroxide, dibutyl peroxide, cumene hydroperoxide, butyl hydroperoxide as organic peroxides, hydrogen peroxide, peroxides as inorganic peroxides. Ammonium sulfate, potassium persulfate, etc., 2-azo-bis-isobutyronitrile, 2-azo-bis-propionitrile, 2-azo-bis-cyclohexanedinitrile, etc. as diazo compounds, diazoaminobenzene, p-nitrobenzenediazonium Etc.

When a compound that initiates radical polymerization by the action of light is used, the coating is cured by irradiation with active energy rays.
Examples of such radical photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds , Disulfide compounds, fluoroamine compounds and aromatic sulfoniums. Examples of acetophenones include 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-4-methylthio-2-morpholinopropiophenone and 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone is included. Examples of benzoins include benzoin benzene sulfonate, benzoin toluene sulfonate, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether. Examples of the benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone. Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Sensitizing dyes can also be preferably used in combination with these photoradical polymerization initiators.

  The amount of the compound that initiates radical polymerization by the action of heat or light may be an amount that can initiate polymerization of the carbon-carbon double bond, and is based on the total solid content in the low refractive index layer forming composition. 0.1-15 mass% is preferable, More preferably, it is 0.5-10 mass%, Most preferably, it is 2-5 mass%.

  The solvent contained in the low refractive index layer coating liquid composition is not particularly limited as long as the composition containing the fluorine-containing copolymer is uniformly dissolved or dispersed without causing precipitation. A solvent can also be used in combination. Preferred examples include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (ethyl acetate, butyl acetate, etc.), ethers (tetrahydrofuran, 1,4-dioxane, etc.), alcohols (methanol, ethanol, isopropyl). Alcohol, butanol, ethylene glycol, etc.), aromatic hydrocarbons (toluene, xylene, etc.), water and the like.

  The low refractive index layer may contain a filler (for example, inorganic fine particles and organic fine particles), a silane coupling agent, a slip agent (silicone compound such as dimethyl silicone), a surfactant, etc. in addition to the fluorine-containing compound. it can. In particular, it is preferable to contain inorganic fine particles, a silane coupling agent, and a slip agent.

  As the inorganic fine particles, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride) and the like are preferable. Particularly preferred is silicon dioxide (silica). The mass average diameter of primary particles of the inorganic fine particles is preferably 1 to 150 nm, more preferably 1 to 100 nm, and most preferably 1 to 80 nm. It is preferable that the inorganic fine particles are more finely dispersed in the outermost layer. The shape of the inorganic fine particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, a short fiber shape, a ring shape, or an indefinite shape. In order to lower the refractive index, hollow silica is preferable.

The hollow silica preferably has a refractive index of 1.17 to 1.40, more preferably 1.17 to 1.35, and most preferably 1.17 to 1.30. The refractive index here represents the refractive index of the entire particle, and does not represent the refractive index of only the outer shell silica forming the hollow silica particles. At this time, when the radius of the cavity in the particle is a and the radius of the particle outer shell is b, the porosity x is expressed by the following formula (VIII).
(Formula VIII)
^{x = (4πa 3/3)} / (4πb 3/3) × 100
= (A / b) ³ × 100
The porosity x is preferably 10 to 60%, more preferably 20 to 60%, and most preferably 30 to 60%. If hollow silica particles are made to have a lower refractive index and a higher porosity, the thickness of the outer shell becomes thinner and the strength of the particles becomes weaker. From the viewpoint of scratch resistance, the low refractive index is less than 1.17. Rate particles do not hold.
A method for producing hollow silica is described in, for example, Japanese Patent Application Laid-Open Nos. 2001-233611 and 2002-79616.
The blending ratio of the hollow silica is preferably 30% by mass or more, more preferably 40 to 70% by mass in the total solid content of the composition for forming a low refractive index layer.

  As the silane coupling agent, a compound represented by the following general formula A and / or a derivative compound thereof can be used. Preferred are silane coupling agents containing a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an alkyl group, an alkoxysilyl group, an acyloxy group, and an acylamino group, and particularly preferred are an epoxy group and a polymerizable acyloxy group ( (Meth) acryloyl), a silane coupling agent containing a polymerizable acylamino group (acrylamino, methacrylamino).

Formula A
_{^{(R 10) p -Si (X}} ) 4-p
(In the formula, R ¹⁰ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. X represents a hydroxyl group or a hydrolyzable group. P represents an integer of 1 to 3.)

Particularly preferred among the compounds represented by formula A are compounds having a (meth) acryloyl group as a crosslinkable or polymerizable functional group, such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxy. Silane etc. are mentioned.
As the slip agent, dimethyl silicone and a fluorine-containing compound into which a polysiloxane segment is introduced are preferable.

{Low refractive index layer forming step}
The low refractive index layer is irradiated with an ionizing radiation curable resin (B) or other optional components contained or dispersed at the same time as application or after application, light irradiation, electron beam irradiation or heating. It is preferably formed by a crosslinking reaction by polymerization or a polymerization reaction.
The oxygen concentration during curing of the low refractive index layer is preferably 0.3% or less, more preferably 0.1% or less, and most preferably 0.05% or less. It is preferable that the amount of irradiation is 250 mJ / cm ² or more, more preferably 500 mJ / cm ² or more, most preferably 750 mJ / cm ² or more. Adhesion with the high refractive index layer can be improved by adjusting the oxygen concentration and the irradiation amount within the above ranges, which is preferable.

[Medium refractive index layer]
As described above, in order to produce an antireflection film having better antireflection performance, it is preferable to provide a middle refractive index layer between the high refractive index layer and the transparent substrate.
The medium refractive index layer can be similarly produced using the same material as the high refractive index layer, and the refractive index can be adjusted by controlling the content of the inorganic fine particles.
The refractive index of the middle refractive index layer in the antireflection film of the present invention is adjusted so as to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. High, medium and low refractive indices are relative. The refractive index of the middle refractive index layer is preferably 1.55 to 1.80. The haze of the medium refractive index layer is preferably 3% or less.
The thickness of the medium refractive index layer is preferably 20 to 90 nm from the viewpoint of reflection characteristics (reflectance and reflection color), and more preferably 30 to 80 nm.

[Hard coat layer]
The hard coat layer is a layer provided on the surface of the transparent substrate as necessary to impart physical strength to the antireflection film.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of an ionizing radiation curable compound. For example, it is formed by applying a composition for forming a hard coat layer containing an ionizing radiation-curable polyfunctional monomer or polyfunctional oligomer on a transparent substrate, and subjecting the polyfunctional monomer or polyfunctional oligomer to a crosslinking reaction or a polymerization reaction. can do. Further, the hard coat layer forming composition may contain inorganic fine particles in order to adjust the refractive index and strength of the hard coat layer.
The functional group of the ionizing radiation-curable polyfunctional monomer or polyfunctional oligomer is preferably a light, electron beam, or radiation polymerizable group, and among them, a photopolymerizable functional group is preferable.

  Examples of the photopolymerizable functional group include unsaturated polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group is preferable.

  Specific examples of the ionizing radiation-curable polyfunctional monomer having a photopolymerizable functional group include those of alkylene glycols such as neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, propylene glycol di (meth) acrylate ( (Meth) acrylic acid diesters; (meth) of polyoxyalkylene glycols such as triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate and polypropylene glycol di (meth) acrylate Acrylic acid diesters; (meth) acrylic acid diesters of polyhydric alcohols such as pentaerythritol di (meth) acrylate; 2,2-bis {4- (acryloxy-diethoxy) phenyl} propane, 2 And (meth) acrylic acid diesters of ethylene oxide or propylene oxide adducts such as 2-bis {4- (acryloxy / polypropoxy) phenyl} propane.

  Furthermore, epoxy (meth) acrylates, urethane (meth) acrylates, and polyester (meth) acrylates are also preferably used as the photopolymerizable polyfunctional monomer.

  Among these, esters of polyhydric alcohol and (meth) acrylic acid are preferable. More preferably, a polyfunctional monomer having 3 or more (meth) acryloyl groups in one molecule is preferable. Specifically, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, 1,2,4-cyclohexanetetra (meth) acrylate, pentaglycerol triacrylate, pentaerythritol tetra (meth) acrylate, penta Erythritol tri (meth) acrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol triacrylate, tripentaerythritol hexatriacrylate, etc. Is mentioned.

Two or more polyfunctional monomers may be used in combination.
The composition for forming a hard coat layer preferably contains a photopolymerization initiator used for the polymerization reaction of the polyfunctional monomer. As the photopolymerization initiator, a photoradical polymerization initiator and a photocationic polymerization initiator are preferable, and a photoradical polymerization initiator is particularly preferable.
Examples of the photo radical polymerization initiator include acetophenones, benzophenones, Michler's benzoylbenzoate, α-amyloxime ester, tetramethylthiuram monosulfide, and thioxanthones.

  Commercially available radical photopolymerization initiators can also be used. For example, KAYACURE (DETX-S, BP-100, BDKM, CTX, BMS, 2-EAQ, ABQ, CPTX, EPD manufactured by Nippon Kayaku Co., Ltd. , ITX, QTX, BTC, MCA, etc.), Irgacure (651, 184, 500, 907, 369, 1173, 2959, 4265, 4263, etc.) manufactured by Ciba Geigy Japan, Esacure (KIP100F, KB1, manufactured by Sartomer) EB3, BP, X33, KT046, KT37, KIP150, TZT) and the like.

In particular, photocleavable photoradical polymerization initiators are preferred. The photocleavable photoradical polymerization initiator is described in the latest UV curing technology (P.159, issuer; Kazuhiro Takashiro, publisher; Technical Information Association, Inc., published in 1991).
Examples of commercially available photocleavable photoradical polymerization initiators include Irgacure (651, 184, 907) manufactured by Nippon Ciba-Geigy Co., Ltd.

It is preferable to use a photoinitiator in the range of 0.1-15 mass parts with respect to 100 mass parts of polyfunctional monomers, More preferably, it is the range of 1-10 mass parts.
In addition to the photopolymerization initiator, a photosensitizer may be used. Specific examples of the photosensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, Michler's ketone and thioxanthone.
Examples of commercially available photosensitizers include KAYACURE (DMBI, EPA) manufactured by Nippon Kayaku Co., Ltd.
The photopolymerization reaction is preferably performed by ultraviolet irradiation after coating and drying of the layer.

Moreover, the composition for forming a hard coat layer may contain an oligomer and / or polymer having a mass average molecular weight of 500 or more for imparting brittleness.
Examples of the oligomer and polymer include (meth) acrylate-based, cellulose-based, and styrene-based polymers, urethane acrylate, and polyester acrylate. Preferable examples include poly (glycidyl (meth) acrylate) and poly (allyl (meth) acrylate) having a functional group in the side chain.

  The content of the oligomer and / or polymer obtained by polymerizing the polyfunctional monomer or oligomer in the hard coat layer is preferably 5 to 80% by mass, more preferably based on the total solid mass of the hard coat layer. Is 25 to 70% by mass, particularly preferably 35 to 65% by mass.

  Further, the hard coat layer may contain matte particles in order to impart antiglare properties. As the mat particles, any of those usually used in a hard coat layer can be used.

The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400.
Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.
In the formation of the hard coat layer, when the ionizing radiation curable compound is formed by a crosslinking reaction or a polymerization reaction, the crosslinking reaction or the polymerization reaction is preferably performed in an atmosphere having an oxygen concentration of 10% by volume or less. By forming in an atmosphere having an oxygen concentration of 10% by volume or less, a hard coat layer excellent in physical strength and chemical resistance can be formed.
Preferably, it is formed by a crosslinking reaction or polymerization reaction of an ionizing radiation curable compound in an atmosphere having an oxygen concentration of 6% by volume or less, more preferably an oxygen concentration of 4% by volume or less, particularly preferably an oxygen concentration of 2 Volume% or less, most preferably 1 volume% or less.

As a method of reducing the oxygen concentration to 10% by volume or less, it is preferable to replace the atmosphere (nitrogen concentration of about 79% by volume, oxygen concentration of about 21% by volume) with another gas, particularly preferably replacement with nitrogen (nitrogen purge). It is to be.
The hard coat layer is preferably constructed by applying a hard coat layer forming composition containing a coating solvent to the surface of the transparent substrate.

As the coating solvent, a ketone solvent is preferably used. By using the ketone solvent, the adhesion between the surface of the transparent substrate (particularly, the triacetyl cellulose support) and the hard coat layer is further improved.
Particularly preferred coating solvents are methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
The coating solvent may contain a solvent other than the ketone solvent.
In the coating solvent, the content of the ketone solvent is preferably 10% by mass or more of the total solvent contained in the coating composition. Preferably it is 30 mass% or more, More preferably, it is 60 mass% or more.
The thickness of the hard coat layer is preferably 2 to 10 μm from the viewpoint of hardness, and more preferably 3 to 8 μm.
Further, the refractive index of the hard coat layer is preferably 1.47 to 1.53, from the viewpoint that the interference unevenness due to the hard coat layer can be made inconspicuous, and preferably 1.48 to 1.52. Further preferred.

[Other layers]
The antireflection film may be provided with layers other than those described above. For example, an adhesive layer, a shield layer, a sliding layer, or an antistatic layer may be provided. The shield layer is provided to shield electromagnetic waves and infrared rays.
In addition, when an antireflection film is applied to a liquid crystal display device, an undercoat layer to which particles having an average particle diameter of 0.1 to 10 μm are added is newly constructed or a hard coat layer for the purpose of improving viewing angle characteristics. The above particles can be added to form a light scattering hard coat layer. The average particle diameter of the particles is preferably 0.2 to 5.0 μm, more preferably 0.3 to 4.0 μm, and particularly preferably 0.5 to 3.5 μm.

  The refractive index of the particles is preferably 1.35 to 1.80, more preferably 1.40 to 1.75, and still more preferably 1.45 to 1.75. The narrower the particle size distribution, the better.

Further, the refractive index of the particles and the portion other than the particles of the undercoat layer or the light diffusing hard coat layer (a binder component mainly composed of a resin such as a polyfunctional monomer, which may contain inorganic fine particles for adjusting the refractive index. ) Is preferably 0.02 or more. More preferably, the difference in refractive index is 0.03 to 0.5, more preferably the difference in refractive index is 0.05 to 0.4, and particularly preferably the difference in refractive index is 0.07 to 0.3. .
As the particles to be added to the undercoat layer, various inorganic particles or organic particles satisfying the above refractive index can be used.
The undercoat layer is preferably constructed between the hard coat layer and the transparent substrate. It can also serve as a hard coat layer.
When particles having an average particle size of 0.1 to 10 μm are added to the undercoat layer, the haze of the undercoat layer is preferably 3 to 60%. More preferably, it is 5 to 50%, further preferably 7 to 45%, particularly preferably 10 to 40%.

[Method for producing antireflection film]
The production method of the antireflection film of the present invention is as follows:
A high refractive index layer-forming composition containing an ionizing radiation curable resin (A) is applied on a transparent substrate directly or via another layer and cured to have a surface roughness of 1 to 10 nm. A high refractive index layer forming step of forming a high refractive index layer;
A low-refractive-index layer forming step in which a low-refractive-index layer is formed by directly applying and curing a low-refractive-index layer-forming composition containing an ionizing radiation curable resin (B) on the high-refractive index layer; Containing. The high refractive index layer forming step and the low refractive index layer forming step are as described above in each section.
And in the manufacturing method of the antireflective film of this invention, in the said high refractive index layer formation process, the surface double bond amount A before hardening of this high refractive index layer and the residual surface double bond amount B after hardening The oxygen concentration and the irradiation amount during curing are controlled so that the ratio of ≦ 0.3 ≦ B / A ≦ 0.9, preferably 0.3 ≦ B / A ≦ 0.6. It is characterized by that.
The oxygen concentration such that the ratio falls within the above range is preferably 2% or less, more preferably 1% or less, still more preferably 0.5% or less, and most preferably 0.1% or less. Moreover, it is preferable that the irradiation amount at the time of the said hardening shall be 200 mJ / cm < ² > or less.
That is, it is particularly preferable that the oxygen concentration is 0.5% or less and the irradiation amount is 200 mJ / cm ² or less, and further the oxygen concentration is 0.1% or less and the irradiation amount is 200 mJ / cm ² or less.
The oxygen concentration can be controlled by changing the flow rate of nitrogen or the mixing ratio of nitrogen and air.

Other than the above, it can be carried out in the same manner as a generally known production method.
Each layer constituting the antireflection film can be formed by a coating method such as a wire bar coating method, a gravure coating method, a micro gravure method, or a die coating method. The microgravure method and the gravure method are preferable from the viewpoint of eliminating the drying unevenness by minimizing the wet coating amount, and the gravure method is preferable from the viewpoint of the film thickness uniformity in the width direction and the film thickness uniformity in the longitudinal direction over time. Particularly preferred. At least two layers of the plurality of optical thin films of the antireflection film of the present invention are formed by the steps of feeding the support film once, forming each optical thin film, and winding the film. It is preferable from the viewpoint of production cost, and when the antireflection layer has a three-layer structure, it is more preferable to form the three layers in one step. In such a production method, a plurality of coating stations and drying / curing zone sets, preferably the same number or more as the number of optical thin films, are cascaded between the feeding and winding of the support film of the coating machine. This is achieved by providing.

[Protective film for polarizing plate]
The antireflection film of the present invention can be used as a surface protective film (protective film for polarizing plate) of a polarizing film in a polarizing plate. At this time, the surface of the transparent substrate opposite to the side having the high refractive index layer, that is, the surface to be bonded to the polarizing film is hydrophilized so that the adhesive property with the polarizing film containing polyvinyl alcohol as a main component is improved. It is preferable to improve.

As the transparent substrate, it is particularly preferable to use a triacetyl cellulose film as described above.
As a method for producing a protective film for a polarizing plate using the antireflection film of the present invention, (1) each layer (eg, high refractive index layer, hard coat layer) on one surface of a transparent substrate previously saponified. (2) After coating each of the above layers (eg, high refractive index layer, hard coat layer, low refractive index layer, outermost layer, etc.) on one surface of the transparent substrate. The method of saponifying the side to be bonded to the polarizing film can be considered. However, since (1) is hydrophilicized to the surface on which the antireflection layer is to be applied, the adhesion between the transparent substrate and the antireflection layer is considered. Therefore, the method (2) is preferable.

[Saponification]
Hereinafter, the saponification treatment will be described in detail.
(1) Immersion method An antireflection film is immersed in an alkaline solution under appropriate conditions to saponify all surfaces that are reactive with alkali on the entire surface of the film, requiring no special equipment. Therefore, it is preferable from the viewpoint of cost. The alkaline liquid is preferably a sodium hydroxide aqueous solution. A preferred concentration is 0.5 to 3 mol / l, particularly preferably 1 to 2 mol / l. The liquid temperature of a preferable alkali liquid is 30-70 degreeC, Most preferably, it is 40-60 degreeC.
The combination of the above saponification conditions is preferably a combination of relatively mild conditions, but can be set according to the material and configuration of the antireflection film and the target contact angle.
After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by immersing in a dilute acid so that the alkaline component does not remain in the film.

By saponification treatment, the surface of the transparent substrate opposite to the surface having the antireflection layer is hydrophilized. As a protective film for a polarizing plate, the transparent surface of a transparent substrate is used by adhering it to a polarizing film.
The hydrophilized surface is effective for improving the adhesiveness with the adhesive layer mainly composed of polyvinyl alcohol.
In the saponification treatment, the lower the contact angle of water on the surface of the transparent substrate opposite to the side having the high refractive index layer, the better from the viewpoint of adhesion to the polarizing film, while the immersion method simultaneously increases the high refractive index. Since the surface having the layer is damaged by alkali, it is important to set the reaction conditions to the minimum necessary. As an index of damage received by the antireflection layer due to alkali, the surface of the transparent substrate opposite to the side having the antireflection layer, that is, when the contact angle to water of the bonding surface of the antireflection film is used, particularly the transparent substrate. Is 30 to 50 degrees, preferably 30 to 50 degrees, more preferably 40 to 50 degrees as the contact angle. If it is 50 degrees or more, there is a problem in the adhesion to the polarizing film, which is not preferable. On the other hand, if the angle is less than 20 degrees, the damage received by the antireflection film is too large, and physical strength and light resistance are impaired.

(2) Alkaline solution coating method As a means for avoiding damage to the antireflection film in the above-described dipping method, the alkali solution is applied only on the surface opposite to the surface having the antireflection film under appropriate conditions, heated, and washed with water. A drying alkali solution coating method is preferably used. The application in this case means that an alkali solution or the like is brought into contact only with the surface to be saponified, and at this time, the contact angle with respect to water of the bonded surface of the antireflection film is 10 to 50 degrees. It is preferable to perform a saponification treatment. In addition to the application, it may include spraying, contact with a belt containing liquid, or the like. By adopting these methods, a separate facility and process for applying an alkaline solution are required, which is inferior to the immersion method (1) from the viewpoint of cost. On the other hand, since the alkali solution contacts only the surface to be saponified, the opposite surface can have a layer using a material that is weak against the alkali solution. For example, vapor deposition films and sol-gel films have various effects such as corrosion, dissolution, and peeling due to alkali solution, so it is not desirable to use the immersion method. Is possible.

  In any of the saponification methods (1) and (2), since each layer can be formed by unwinding from a roll-shaped transparent substrate, a series of operations can be performed in addition to the above-described antireflection film manufacturing process. You can go. Furthermore, the polarizing plate can be produced more efficiently than the same operation with a single wafer by continuously performing the pasting step with the polarizing plate made of the transparent substrate that has been unwound in the same manner.

[Polarizer]
The polarizing plate of the present invention is characterized in that the above-described antireflection film of the present invention is used as a protective film on at least one side.
The preferable polarizing plate of this invention has the antireflection film of this invention in at least one of the protective film (protective film for polarizing plates) of a polarizing film, as shown in FIG. That is, in the polarizing plate shown in FIG. 1, the transparent substrate (1) of the antireflection film is adhered to the polarizing film (7) through the adhesive layer (6) made of polyvinyl alcohol, and the other polarizing film The protective film (8) is bonded to the main surface opposite to the main surface to which the antireflection film of the polarizing film (7) is bonded via the adhesive layer (6). The other surface of the protective film (8) has a pressure-sensitive adhesive layer (9) on the surface main surface opposite to the main surface bonded to the polarizing film.

By using the antireflection film of the present invention as a protective film for a polarizing plate, it is possible to produce a polarizing plate with excellent physical strength and excellent scratch resistance while maintaining good optical properties. Thinning is possible.
Further, by preparing a polarizing plate using the antireflection film of the present invention as one of the protective films for polarizing plates and an optical compensation film having optical anisotropy described later as the other protective film of the polarizing film, Thus, a polarizing plate capable of improving the contrast in the bright room of the liquid crystal display device and greatly widening the vertical and horizontal viewing angles can be produced.

[Optical compensation film]
The optical compensation film (retardation film) can improve the viewing angle characteristics of the liquid crystal display screen.
As the optical compensation film, a known film can be used. In particular, from the viewpoint of widening the viewing angle, an optical anisotropy composed of a compound having a discotic structural unit described in JP-A-2001-100042 is used. An optical compensation film characterized in that the angle formed between the discotic compound and the support varies with the distance from the support.
The angle preferably increases as the distance from the support surface side of the optically anisotropic layer increases.

When the optical compensation film is used as a protective film for the polarizing film, the surface on the side to be bonded to the polarizing film is preferably saponified, and is preferably performed according to the saponifying process.
An embodiment in which the optically anisotropic layer further contains a cellulose ester, an embodiment in which an alignment layer is formed between the optically anisotropic layer and the support, and an optical compensation film having the optically anisotropic layer It is also preferable that the support has an optically negative uniaxial property, has an optical axis in the normal direction of the support surface, and satisfies the following conditions.
20 ≦ {(nx + ny) / 2−nz} × d ≦ 400
In the above conditional expression, nx is the refractive index in the slow axis direction (direction in which the refractive index is maximum) in the film plane, and ny is the fast axis direction in the film plane (direction in which the refractive index is minimum). Where nz is the refractive index in the thickness direction of the film, and d is the thickness of the optical compensation layer.

[Image display device]
The polarizing plate can be applied to an image display device such as a liquid crystal display device (LCD) or an electroluminescence display (ELD).
The image display device of the present invention has the above-described antireflection film of the present invention.
Further, a TN, STN, VA, IPS, OCB, or ECB mode transmissive, reflective, or transflective liquid crystal display device including at least one polarizing plate of the present invention described above may be used.
In such a case, a polarizing plate having the antireflection film of the present invention as shown in FIG. 1 is used by bonding directly to the glass of the liquid crystal cell of the liquid crystal display device or through another layer.

The polarizing plate using the antireflection film used in the present invention includes twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), and optically compensated bend cell (OCB). It can be preferably used for a transmissive, reflective, or transflective liquid crystal display device of the mode.
When used in a transmissive or transflective liquid crystal display device, it is used in combination with a commercially available brightness enhancement film (a polarized light separation film having a polarization selective layer, such as D-BEF manufactured by Sumitomo 3M Co., Ltd.). Thus, a display device with higher visibility can be obtained.
Further, by combining with a λ / 4 plate, it can be used to reduce reflected light from the surface and the inside as a polarizing plate for reflective liquid crystal or a surface protective plate for organic EL display.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention should not be construed as being limited thereto.

(Preparation of coating solution for hard coat layer)
The following composition was put into a mixing tank and stirred to obtain a hard coat layer coating solution.
Composition: 750.0 parts by mass of trimethylolpropane triacrylate (Biscoat V # 295, manufactured by Osaka Organic Chemical Co., Ltd.), 270.0 parts by mass of poly (glycidyl methacrylate) having a mass average molecular weight of 15,000, and methyl ethyl ketone 730 0.0 parts by mass, 500.0 parts by mass of cyclohexanone and 50.0 parts by mass of a photopolymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals) were added and stirred. Subsequently, it filtered with the filter made from a polypropylene with the hole diameter of 0.4 micrometer, and obtained the composition for hard-coat layer formation.

(Preparation of titanium dioxide fine particle dispersion)
As the titanium dioxide fine particles as inorganic fine particles, titanium dioxide fine particles (MPT-129C, manufactured by Ishihara Sangyo Co., Ltd., TiO ₂ : Co containing cobalt and surface-treated with aluminum hydroxide and zirconium hydroxide) ₃ O ₄ : Al ₂ O ₃ : ZrO ₂ = 90.5: 3.0: 4.0: 0.5 mass ratio) was used.
47.1 parts by mass of the following dispersant as an ionizing radiation curable resin and 701.8 parts by mass of cyclohexanone were added to 257.1 parts by mass of the titanium dioxide fine particles and dispersed by dynomill, and titanium dioxide having a mass average diameter of 70 nm. A dispersion was prepared.

(Preparation of medium refractive index layer forming composition)
In 99.1 parts by mass of the above titanium dioxide dispersion, 68.0 parts by mass of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.), a photopolymerization initiator (Irgacure 907) ) 3.6 parts by mass, 1.2 parts by mass of photosensitizer (Kayacure-DETX, manufactured by Nippon Kayaku Co., Ltd.), 279.6 parts by mass of methyl ethyl ketone and 1049.0 parts by mass of cyclohexanone were added and stirred. After sufficiently stirring, the mixture was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a composition for forming a medium refractive index layer. The refractive index of the coating film formed using this coating solution was 1.666 (550 nm).

(Preparation of High Refractive Index Layer Composition Hn-1)
To 287.0 parts by mass of the above titanium dioxide dispersion, 89.1 parts by mass of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.), a photopolymerization initiator (Irgacure 907) 7.4 parts by mass, manufactured by Ciba Specialty Chemicals Co., Ltd., 2.5 parts by mass of photosensitizer (Kayacure-DETX, manufactured by Nippon Kayaku Co., Ltd.), 526.2 parts by mass of methyl ethyl ketone, and 587 of cyclohexanone .8 parts by mass was added and stirred. The solution was filtered through a polypropylene filter having a pore diameter of 0.4 μm to prepare a coating solution Hn-1 for a high refractive index layer. The refractive index of the coating film formed using this coating solution was 1.763 (550 nm).

(Preparation of composition Hn-2 for forming a high refractive index layer)
In 394.4 parts by mass of the above titanium dioxide dispersion, 60.1 parts by mass of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.), a photopolymerization initiator (Irgacure 907) Ciba Specialty Chemicals Co., Ltd.) 5.0 parts by mass, photosensitizer (Kayacure-DETX, Nippon Kayaku Co., Ltd.) 1.7 parts by mass, methyl ethyl ketone 526.3 parts by mass, and cyclohexanone 512 .6 parts by mass was added and stirred. The mixture was filtered through a polypropylene filter having a pore diameter of 0.4 μm to prepare a coating solution Hn-2 for a high refractive index layer. The refractive index of the coating film formed using this coating solution was 1.838 (550 nm).

(Preparation of composition Hn-3 for forming a high refractive index layer)
To 469.8 parts by mass of the above titanium dioxide dispersion, 40.0 parts by mass of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.), a photopolymerization initiator (Irgacure 907) 3.3 parts by mass, manufactured by Ciba Specialty Chemicals Co., Ltd., 1.1 parts by mass of photosensitizer (Kayacure-DETX, manufactured by Nippon Kayaku Co., Ltd.), 526.2 parts by mass of methyl ethyl ketone, and cyclohexanone 459 .6 parts by mass was added and stirred. The solution was filtered through a polypropylene filter having a pore diameter of 0.4 μm to prepare a coating solution Hn-3 for a high refractive index layer. The refractive index of the coating film formed using this coating solution was 1.867 (550 nm).

(Preparation of High Refractive Index Layer Composition Hn-4)
The composition Hn-3 for forming a high refractive index layer was prepared in the same manner as Hn-3, except that a dispersion having a titanium dioxide fine particle size of 120 nm was used.

(Synthesis of perfluoroolefin copolymer (1))

Into a stainless steel autoclave with a stirrer of 100 ml, 40 ml of ethyl acetate, 14.7 g of hydroxyethyl vinyl ether and 0.55 g of dilauroyl peroxide were charged, and the inside of the system was deaerated and replaced with nitrogen gas. Further, 25 g of hexafluoropropylene (HFP) was introduced into the autoclave and the temperature was raised to 65 ° C. The pressure when the temperature in the autoclave reached 65 ° C. was 5.4 kg / cm ² . The reaction was continued for 8 hours while maintaining the temperature, and when the pressure reached 3.2 kg / cm ² , the heating was stopped and the mixture was allowed to cool. When the internal temperature dropped to room temperature, unreacted monomers were driven out, the autoclave was opened, and the reaction solution was taken out. The obtained reaction solution was poured into a large excess of hexane, and the polymer was precipitated by removing the solvent by decantation. Further, this polymer was dissolved in a small amount of ethyl acetate and reprecipitated twice from hexane to completely remove the residual monomer. After drying, 28 g of polymer was obtained. Next, 20 g of the polymer was dissolved in 100 ml of N, N-dimethylacetamide, and 11.4 g of acrylic acid chloride was added dropwise under ice cooling, followed by stirring at room temperature for 10 hours. Ethyl acetate was added to the reaction solution, washed with water, the organic layer was extracted and concentrated, and the resulting polymer was reprecipitated with hexane to obtain 19 g of the perfluoroolefin copolymer (1) as a fluoropolymer. The resulting polymer had a refractive index of 1.421.

(Preparation of composition Ln-1 for forming a low refractive index layer)
Perfluoroolefin copolymer (1) was dissolved in methyl ethyl ketone so as to have a concentration of 7% by mass, and terminal methacrylate group-containing silicone resin X-22-164C (manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the copolymer. 3% of a photoradical generator Irgacure 907 (manufactured by Ciba Specialty Chemicals Co., Ltd.) was added in an amount of 5% by mass to the copolymer to prepare a composition Ln-1 for forming a low refractive index layer. The refractive index of the coating film formed using this coating solution was 1.450 (550 nm).

(Preparation of sol solution a)
A stirrer, a reactor equipped with a reflux condenser, 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of diisopropoxyaluminum ethyl acetoacetate were added and mixed. Thereafter, 30 parts of ion-exchanged water was added and reacted at 60 ° C. for 4 hours, and then cooled to room temperature to obtain sol solution a. The mass average molecular weight was 1600, and among the components higher than the oligomer component, the component having a molecular weight of 1000 to 20000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.

(Preparation of hollow silica dispersion)
Hollow silica fine particle sol (isopropyl alcohol silica sol, CS60-IPA manufactured by Catalyst Chemical Industry Co., Ltd., average particle diameter 60 nm, shell thickness 10 nm, silica concentration 20%, silica particle refractive index 1.31) in 500 parts by mass, acryloyloxy After adding 30 parts by mass of propyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-5103) and 1.5 parts by mass of diisopropoxyaluminum ethyl acetate, 9 parts by mass of ion-exchanged water were added. After making it react at 60 degreeC for 8 hours, it cooled to room temperature, added 1.8 mass parts of acetylacetone, and obtained the hollow silica dispersion liquid. The resulting hollow silica dispersion had a solid content concentration of 18% by mass and a refractive index after solvent drying of 1.31.

(Preparation of composition Ln-2 for forming a low refractive index layer)
Perfluoroolefin copolymer (1) 41.6 parts by mass, mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) 10.4 parts by mass, hollow silica 30.0 Parts by mass, photoradical generator Irgacure 907 (Ciba Specialty Chemicals Co., Ltd.) 2.2%, terminal methacrylate group-containing silicone resin X-22-164C (Shin-Etsu Chemical Co., Ltd.) 2.3 parts by mass, 13.5 parts by mass of the sol liquid a (all the above are mass% of only the solid content) is mixed and dissolved in methyl ethyl ketone so that the solid content concentration becomes 7 mass%, and the composition Ln-2 for forming a low refractive index layer is obtained. Prepared. The refractive index of the coating film formed using this coating solution was 1.425 (550 nm).

(Preparation of antireflection film)
A hard coat layer coating solution was applied onto a triacetyl cellulose film (TD-80UF, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm using a gravure coater. After drying at 100 ° C., using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) while purging with nitrogen so that the atmosphere has an oxygen concentration of 1.0 vol% or less, an irradiance of 400 mW / The coating layer was cured by irradiating with ultraviolet rays of cm ² and an irradiation amount of 300 mJ / cm ² to form a hard coat layer having a thickness of 8 μm. The refractive index of the hard coat layer thus prepared was 1.53 (550 nm).
A gravure having three coating stations on a hard coat layer, three of a composition for forming a medium refractive index layer, a composition for forming a high refractive index layer, and a composition for forming a low refractive index layer in the combinations shown in Table 1. Each of the antireflection films of Samples A to L shown in Table 1 was obtained by coating using a coater. The coating conditions were adjusted so that the thickness of each layer was 65 nm, 102 nm, and 82 nm. And after completion | finish of application | coating of each layer, drying and hardening were performed.

Drying and curing were performed as follows.
The medium refractive index layer was dried at 110 ° C. for 15 seconds, and the ultraviolet curing condition was a 180 W / cm air-cooled metal halide lamp (eye graphics) while purging with nitrogen so that the atmosphere had an oxygen concentration of 1.0 vol% or less. The amount of irradiation was 400 mW / cm ² and the amount of irradiation was 400 mJ / cm ² .

  The drying condition of the high refractive index layer is 110 ° C. for 15 seconds, and the ultraviolet curing condition is a 240 W / cm air-cooled metal halide lamp (made by Eye Graphics Co., Ltd.) while purging with nitrogen so that the oxygen concentration atmosphere shown in Table 1 is obtained. ) Using the irradiance and irradiation amount shown in Table 1.

The low refractive index layer was dried at 90 ° C. for 15 seconds, and the ultraviolet curing condition was 240 W / cm air-cooled metal halide lamp (eye graphics) while purging with nitrogen so that the atmosphere had an oxygen concentration of 0.1% by volume or less. The amount of irradiation was 600 mW / cm ² and the irradiation amount was 600 mJ / cm ² .

The film thus prepared was saponified under the following conditions to obtain antireflection films A to L.
(Saponification)
Immerse in a 1.5 mol / L aqueous sodium hydroxide solution maintained at 55 ° C. for 2 minutes.
Flush with running water for 15 seconds.
Immerse in 0.05 mol / L sulfuric acid kept at 30 ° C. for 20 seconds.
Flush with running water for 15 seconds.
Dry with Celco at 120 ° C for 1 minute.

  The surface roughness of the high refractive index layer, the surface double bond residual ratio B / A, the scratch resistance of the antireflection films A to L, the haze, and the film thickness change of the high refractive index layer before and after forming the low refractive index layer are as follows The method was evaluated. The results are shown in Table 1.

(Surface roughness)
Evaluation was performed using an atomic force microscope (SPI-3800N AFM; manufactured by Seiko Instruments Inc.). On the surface of the produced high refractive index layer, measurement is performed at an area of 1 μm × 1 μm randomly from an area of 100 cm ² , and the average value of the average surface roughness (Ra) at a total of 100 locations (area of 1 mm ² ) is obtained. Asked.

(Surface double bond remaining rate)
The double bond residual ratio on the surface of the high refractive index layer was quantified by X-ray photoelectron spectroscopy (ESCA) after modifying the double bond with Br. This method is also described, for example, on page 63 of “X-ray Photoelectron Spectroscopy” (Maruzen), a surface analysis technology selection edited by the Surface Science Society of Japan.
Specifically, the sample was allowed to stand for 1 hour in a gas phase in a sealed container containing 2% by mass of bromine water, and Br was added to the double bond portion. The signal area intensity of ESCA Br2p and C1s on the sample surface was measured, and the ratio Br / C between them was determined and used as an index of the surface double bond amount. The value of Br / C after curing with respect to Br / C of the high refractive index layer before curing was defined as the residual rate of surface double bonds.

(Abrasion resistance)
Using a steel wool scratch resistance evaluation rubbing tester, a rubbing test was performed under the following conditions.
Sample humidity control conditions: 25 ° C., 60% RH, 2 hours or more.
Rub material: Steel wool (manufactured by Nippon Steel Wool Co., Ltd., Geledo No. 0000) was wound around the rubbing tip (1 cm × 1 cm) of a tester in contact with the sample, and the band was fixed so as not to move.
Travel distance (one way): 10cm
Rubbing speed: 10 cm / second,
Load: 500 g / cm ² ,
Tip contact area: 1 cm × 1 cm,
Number of rubs: 10 round trips.
An oil-based black ink was applied to the back side of the rubbed sample and visually observed with reflected light, and scratches on the rubbed portion were evaluated according to the following criteria.
Even if you look very carefully, you can hardly see any scratches. : ◎
If you look very carefully, you can see a weak wound. : ○
A weak wound is visible. : △
Scratches are visible at first glance. : ×

(Haze)
The haze of the obtained antireflection film was measured using a haze meter MODEL 1001DP (manufactured by Nippon Denshoku Industries Co., Ltd.).

(Change in film thickness of the high refractive index layer before and after the formation of the low refractive index layer)
The back surface of the antireflective film before and after the formation of the low refractive index layer is rubbed with a sandpaper and then painted black with a magic mirror. The specular reflectance and tint spectrophotometer V-550 (manufactured by JASCO Corporation) and adapter ARV-474 Was mounted, and the specular reflectance at an exit angle of -5 ° at an incident angle of 5 ° was measured in a wavelength region of 380 to 780 nm. Optical fitting was performed on the obtained reflection spectrum, and the change in the film thickness of the high refractive index layer before and after the formation of the low refractive index layer was calculated.

As is clear from the results shown in Table 1, the antireflection film A having a surface roughness Ra of less than 1 nm had poor scratch resistance. In addition, the antireflection film D having a surface roughness Ra exceeding 10 nm had good scratch resistance but high haze.
Further, even when the surface roughness Ra was about 4 nm, the antireflection film E having a B / A of less than 0.3 was inferior in scratch resistance. The antireflection film J having a B / A exceeding 0.9 caused interfacial mixing with the high refractive index layer by applying the low refractive index layer, and a clean surface sample could not be obtained.
Examination of antireflection films C, F to I, K, and L that have the same Ra and have the oxygen concentration and the UV irradiation amount adjusted so that B / A falls within the range of 0.3 to 0.9. did. In Samples F and G in which the oxygen concentration was increased from 0.03% to 0.3%, the film thickness change of the high refractive index layer slightly started before and after the low refractive index layer was cured. Since the film thickness of the high refractive index layer was thinner than the intended film thickness, the reflected color of the finished sample was slightly different from the intended color. Samples H, I, and K prepared with an oxygen concentration of 1% and 20% were able to maintain good scratch resistance by adjusting the irradiation amount, but the B / A value increased and the low refractive index layer The film thickness change of the high refractive index layer before and after curing increased. For this reason, the deviation of the reflected color of the completed sample from the intended reflected color slightly increased. Along with this, the manufacturing robustness also decreased.
The antireflective film L in which the same high refractive index layer as that of the antireflective film C is formed and the low refractive index layer is changed to Ln-2 is excellent in scratch resistance like the antireflective film C, and more external light. The reflection of was able to be prevented.

FIG. 1 is a cross-sectional view schematically showing a layer configuration of an embodiment of the antireflection film of the present invention and schematically showing an embodiment of a polarizing plate using the antireflection film of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base | substrate 2 Hard-coat layer 3 Middle refractive index layer 4 High refractive index layer 5 Low refractive index layer (outermost layer)
6 Adhesive layer 7 Polarizing film 8 Surface protective film 9 on the opposite side Adhesive layer

Claims (16)

A high refractive index layer comprising a transparent substrate, a composition for forming a high refractive index layer containing the ionizing radiation curable resin (A), which is formed directly or via another layer on the transparent substrate, and the high refractive index layer An antireflective film having a low refractive index layer formed of a composition for forming a low refractive index layer containing an ionizing radiation curable resin (B) provided directly on the refractive index layer,
The high refractive index layer has irregularities on the surface where the low refractive index layer side is provided, the surface roughness of the irregularities is 1 to 10 nm, and the high refractive index layer has a surface double before curing. An antireflection film, wherein the ratio of the amount of bond A to the amount of residual surface double bond B after curing is 0.3 ≦ B / A ≦ 0.9.   2. The antireflection film according to claim 1, wherein the surface irregularities of the high refractive index layer are derived from the shape of the inorganic fine particles.   The antireflection film according to claim 2, wherein the inorganic fine particles have a particle size of 10 to 100 nm.   4. The antireflection film according to claim 2, wherein the content of the inorganic fine particles in the high refractive index layer is 50% by mass or more.   The antireflection film according to claim 4, wherein the inorganic fine particles are fine particles containing titanium dioxide as a main component.   The antireflection film according to claim 1, wherein the haze is 1.0% or less.   The ratio of the surface double bond amount A before curing and the residual surface double bond amount B after curing in the high refractive index layer is 0.3 ≦ B / A ≦ 0.6. The antireflection film according to any one of claims 1 to 6. The composition for forming a low refractive index layer contains a fluorine polymer represented by the following general formula (1) in an amount of 20% by mass or more based on the total solid content of the composition for forming a low refractive index layer. 8. The antireflection film according to any one of 7 above.

L represents a linking group having 1 to 10 carbon atoms, and X represents a hydrogen atom or a methyl group. x, y, and z represent mol% of each constituent component, and 30 ≦ x ≦ 60, 5 ≦ y ≦ 70, and 0 ≦ z ≦ 65.   The antireflection film according to any one of claims 1 to 8, wherein the low refractive index layer contains 30% by mass or more of hollow silica. A high refractive index layer-forming composition containing an ionizing radiation curable resin (A) is applied on a transparent substrate directly or via another layer and cured to have a surface roughness of 1 to 10 nm. A high refractive index layer forming step of forming a high refractive index layer;
A low-refractive-index layer forming step in which a low-refractive-index layer is formed by applying and curing a low-refractive-index layer-forming composition containing an ionizing radiation curable resin (B) directly on the high-refractive index layer; A method for producing an antireflection film containing
In the high refractive index layer forming step, the ratio of the surface double bond amount A before curing and the residual surface double bond amount B after curing of the high refractive index layer is 0.3 ≦ B / A ≦ 0. 9. A method for producing an antireflection film, comprising controlling the oxygen concentration and the irradiation amount when the high refractive index layer is cured so as to be 9.   In the high refractive index layer forming step, the amount of surface double bonds A of the applied composition for forming a high refractive index layer before curing and the residual surface double bond amount B of the high refractive index layer formed after curing 11. The antireflection film according to claim 10, wherein the oxygen concentration and the irradiation amount during curing of the high refractive index layer are controlled so that the ratio is 0.3 ≦ B / A ≦ 0.6. Production method.   The method for producing an antireflection film according to claim 10 or 11, wherein the oxygen concentration during the curing is controlled to 0.5% or less. The method for producing an antireflection film according to any one of claims 10 to 12, wherein an irradiation amount during the curing is controlled to 200 mJ / cm ² or less.   A polarizing plate using the antireflection film according to claim 1 as a protective film on at least one side.   An image display device comprising the antireflection film according to claim 1.   A TN, STN, VA, IPS, OCB, or ECB mode transmissive, reflective, or transflective liquid crystal display device having at least one polarizing plate according to claim 14.

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