JP6558007B2 - Antireflection film, display device using the antireflection film, and method for selecting antireflection film - Google Patents

Description

  The present invention relates to an antireflection film, a display device using the antireflection film, and a method for selecting an antireflection film.

In recent years, with the shift to terrestrial digital broadcasting and the like, development of display devices capable of displaying ultra-high definition images has been progressing. In order not to impair the image quality of such an ultra-high-definition display device, the surface of the display device is required to have a performance that prevents external light from being reflected.
As means for preventing the reflection of external light, there are mainly anti-glare treatment for reducing the regular reflection light by making the surface uneven, and anti-reflection treatment for reducing the reflectance by the interference action of the multilayer thin film. In recent years, anti-reflection processing that tends to give a high-quality image has become mainstream.

  Multilayer thin films can reduce reflectivity and color as the thin films are stacked, but from the viewpoint of cost effectiveness, many of them use the interference action of two to four layers. As such an antireflection film, for example, one of Patent Document 1 can be mentioned.

  In addition, due to the ultra-high definition of display devices in recent years, even if the display device has a large screen, pixels are no longer an issue, so the number of display devices with a large screen has further increased. In such a large screen display device, the left and right ends of the screen have large emission angles even when viewed from the front. In addition, even when the display device has a convex shape, the emission angles at the left and right ends are large. For this reason, development of an antireflection film having uniformity in color at a wide range of emission angles (hereinafter referred to as “broad color uniformity”) has been underway.

JP 2010-152111 A

However, in a small display device such as a smartphone, since the emission angles at the left and right ends do not widen, the need for a wide range of color uniformity is low, and the color uniformity at a narrow emission angle in the front direction (hereinafter referred to as `` Called "narrow range color uniformity").
Further, an antireflection film developed so as to satisfy a wide range of color uniformity tends to be inferior to a narrow range of color uniformity.

  An object of the present invention is to provide an antireflection film excellent in narrow color uniformity, a display device using the antireflection film, and a method for selecting the antireflection film.

The present invention provides the following antireflection films [1] to [8], a display device using the antireflection film, and a method for selecting the antireflection film.
[1] An antireflection film having a high refractive index layer and a low refractive index layer on a transparent substrate, the antireflection film being opposite to the high refractive index layer side of the transparent substrate of the antireflection film An antireflection film in which the L ^* value, a ^* value, and b ^* value of the Lab color system measured from a sample in which a black plate is bonded to the surface via a transparent adhesive satisfy the following condition (1).
<Condition (1)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, the ^{L *} value at each incident angle, calculates the square root SQ sum of squares of ^{a *} and ^{b *} values. When the difference SQ _di of the square root of the sum of squares of the L ^* value, a ^* value, and b ^* value between each measurement is calculated, the maximum value of SQ _di is 0.25 or less.
[2] The antireflection film according to [1], wherein the L ^* value, a ^* value, and b ^* value of the Lab color system measured from the sample satisfy the following condition (2).
<Condition (2)>
The incident angle of light perpendicularly incident on the surface of the low refractive index layer side of the sample is set to 0 degree, and light is incident on the sample at an interval of 25 degrees from an incident angle of 25 degrees to 45 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, to calculate the square root SQ of the sum of the squares of the ^{L *} value, ^{a *} and ^{b *} values at each incident angle, further, the When the cumulative value SQ _25-45 of the square root SQ of the sum of squares is calculated, the cumulative value SQ _25-45 is 20.00 or more.

[3] The antireflection film as described in [1] or [2] above, wherein a hard coat layer is provided between the transparent substrate and the high refractive index layer.
[4] A display device in which the antireflection film according to any one of the above [1] to [3] is disposed on a display element so that the transparent substrate side of the antireflection film faces the display element.
[5] The display device according to [4], including a touch panel on the display element, and the antireflection film disposed on the touch panel.
[6] The display device according to [4] or [5], wherein a screen size of the display device is a diagonal of 38.1 cm or less.
[7] The display device according to any one of [4] to [6], wherein the number of pixels of the display element is 3840 × 2160 pixels or more.
[8] A black plate on a surface opposite to the high refractive index layer side of the transparent base material of the antireflection film having a high refractive index layer and a low refractive index layer on the transparent base material via a transparent adhesive. The anti-reflection film is selected by making the L ^* value, a ^* value and b ^* value of the Lab color system measured from the sample satisfy the following condition (1). Method.
<Condition (1)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, the ^{L *} value at each incident angle, calculates the square root SQ sum of squares of ^{a *} and ^{b *} values. When the difference SQ _di of the square root of the sum of squares of the L ^* value, a ^* value, and b ^* value between each measurement is calculated, the maximum value of SQ _di is 0.25 or less.

  The antireflection film and display device of the present invention are excellent in color uniformity in a narrow range. Moreover, the selection method of the antireflection film of this invention can select the antireflection film excellent in the color uniformity of a narrow range correctly.

[Antireflection film]
The antireflection film of the present invention is an antireflection film having a high refractive index layer and a low refractive index layer on a transparent substrate, and the antireflection film is on the high refractive index layer side of the transparent substrate of the antireflection film. The L ^* value, a ^* value, and b ^* value of the Lab color system measured from a sample in which a black plate is bonded to the surface opposite to the surface through a transparent adhesive satisfy the following condition (1). .
<Condition (1)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. The L ^* value, a ^* value, and b ^* value of the Lab color system of light are measured, and the square root SQ of the square sum of the a ^* value and b ^* value at each incident angle is calculated. When the difference SQ _di of the square root of the sum of squares of the L ^* value, a ^* value, and b ^* value between each measurement is calculated, the maximum value of SQ _di is 0.25 or less.

In addition, in this invention, the refractive index of the transparent adhesive used for a sample uses that whose refractive index difference with the refractive index of a transparent base material and a black board is less than 0.05.
Further, hereinafter, “the difference SQ _di between the square roots of the L ^* value, the a ^* value, and the b ^* value between the measurements” may be referred to as “SQ _di ”. Further, hereinafter, the “L ^* value, the square root SQ of the a ^* value and the b ^* value” may be referred to as “SQ”.

Condition (1)
It can be said that SQ represents the color, and SQ _di represents the color difference for each angle.
In other words, satisfying the condition (1) means that when the center of the screen is 0 degree, the color uniformity is excellent in a field of view of ± 20 degrees (field of view near the front). In other words, satisfying the condition (1) means that the color uniformity in a narrow range is excellent.
The maximum value of SQ _{di in} condition (1) is preferably 0.20 or less, more preferably 0.15 or less, further preferably 0.10 or less, and 0.08 or less. It is even more preferable.

In the condition (1), the incident angle is measured from 5 degrees to 20 degrees for the following reason.
First, when a human observes an object, the ideal distance (clear vision distance) is 25 to 30 cm. A general-purpose tablet-type display device has a vertical / horizontal length ratio of 5: 3 and is mainly used in a vertical orientation. A tablet-type display device usually has a screen size of 15 inches (diagonal) or less in consideration of portability and handling.
When observing a general-purpose tablet-type display device (with a screen size diagonal of 38.1 cm or less and a vertical / horizontal length ratio of 5: 3) in a normal orientation (vertical orientation) from a clear viewing distance (25-30 cm) The viewing angle at both ends of the screen is 22.7 degrees at the maximum (when the screen size is diagonally 38.1 cm and observed from a distance of 25 cm).
In other words, in a general-purpose tablet display device, the viewing angle hardly exceeds 20 degrees. Therefore, in the condition (1), the measurement is performed from the incident angle of 5 degrees to 20 degrees.

The L ^* value, a ^* value, and b ^* value of the Lab color system in condition (1) are the X value obtained by measuring the X value, Y value, and Z value of CIE XYZ of the regular reflection light of the incident light. , Y value and Z value can be calculated by conversion using a general-purpose conversion formula. In the measurement of the condition (1), the viewing angle, the light source, and the measurement wavelength are preferably set as the following conditions.
Viewing angle: 2 degrees, light source: D65, measurement wavelength: 380 to 780 nm at 0.5 nm intervals The measurement conditions of conditions (2) to (4) described later are also the same as those of condition (1).

In the antireflection film of the present invention, the L ^* value, a ^* value, and b ^* value of the Lab color system measured from the sample preferably satisfy the following condition (2).
<Condition (2)>
The incident angle of light perpendicularly incident on the surface of the low refractive index layer side of the sample is set to 0 degree, and light is incident on the sample at an interval of 25 degrees from an incident angle of 25 degrees to 45 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, to calculate the square root SQ of the sum of the squares of the ^{L *} value, ^{a *} and ^{b *} values at each incident angle, further, the When the cumulative value SQ _25-45 of the square root SQ of the sum of squares is calculated, the cumulative value SQ _25-45 is 20.00 or more.
Hereinafter, the cumulative value SQ _25-45 of SQ with an incident angle of 25 degrees to 45 degrees may be referred to as “SQ _25-45 ”.

Condition (2) means that the tint is strong in a visual field of 25 to 45 degrees when the center of the screen is 0 degrees.
As described above, a general-purpose tablet display device has a maximum viewing angle of 22.7 degrees. Therefore, even if the condition (2) is satisfied, the color uniformity in a narrow range is not adversely affected. In addition, by deliberately enhancing the color of the field of view of 25 to 45 degrees, it is possible to easily reduce the fluctuation range of the SQ value in the range where the incident angle is small, and to easily satisfy the condition (1). Can do.
The SQ _{25-45 in the} condition (2) is more preferably 21.00 or more.

In the antireflection film of the present invention, it is preferable that the L ^* value, a ^* value, and b ^* value of the Lab color system measured from the sample satisfy the following condition (3).
<Condition (3)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, to calculate the square root SQ of the sum of the squares of the ^{L *} value, ^{a *} and ^{b *} values at each incident angle, further, the When the cumulative value SQ _5-20 of the square root SQ of the sum of squares is calculated, the cumulative value SQ _5-20 is 12.00 or less.
Hereinafter, the cumulative value SQ _5-20 of the SQ with the incident angle of 5 degrees to 20 degrees may be referred to as “SQ _5-20 ”.

Satisfying condition (3) together with condition (1) suppresses a rapid change in tint in a narrow angle range near the front direction (0 degree) and suppresses a strong tint in the angle range. Thus, the visibility of the video can be made extremely good.
The SQ _{5-20 in the} condition (3) is more preferably 10.00 or less.

Condition (4)
In the antireflection film of the present invention, the luminous reflectance Y value measured from the sample preferably satisfies the following condition (4).
<Condition (4)>
When the incident angle of light perpendicularly incident on the surface on the low refractive index layer side of the sample is 0 degree and the light is incident on the sample at an incident angle of 5 degrees, the specular reflection of the incident light is visible The reflectance Y value is 1.00% or less.

By satisfying the condition (4), it is possible to suppress a decrease in image quality of the ultra-high definition display device.
In condition (4), the luminous reflectance Y value is more preferably 0.50% or less, further preferably 0.30% or less, and further preferably 0.20% or less.
The luminous reflectance Y value refers to the Y value of the CIE 1931 standard color system.

Configuration of Antireflection Film The antireflection film of the present invention has a basic configuration having a high refractive index layer and a low refractive index layer on a transparent substrate. The high refractive index layer and the low refractive index layer have a role of providing an antireflection function by an optical interference function. The antireflection film may be further provided with an antireflection function by an optical interference function of three or more layers by providing a medium refractive index layer or the like. However, it is not preferable from the viewpoint of cost effectiveness if a multilayer structure is formed too much.
Therefore, the antireflection film of the present invention preferably has an antireflection function by an optical interference function in two layers of a high refractive index layer and a low refractive index layer. In addition, when it has the hard-coat layer mentioned later between a transparent base material and a high-refractive-index layer, a hard-coat layer is made into medium refractive index, a medium-refractive-index layer (hard-coat layer), a high-refractive-index layer, and It is preferable that three layers of the low refractive index layer provide an antireflection function by an optical interference function.

(Transparent substrate)
The transparent substrate of the antireflection film is not particularly limited as long as it is a transparent substrate generally used as the substrate of the antireflection film, but from the viewpoint of material cost, productivity, etc., preferably a plastic film, a plastic sheet, etc. Can be appropriately selected depending on the application.

  As a plastic film or a plastic sheet, what consists of various synthetic resins is mentioned. Synthetic resins include cellulose resins such as triacetyl cellulose resin (TAC), diacetyl cellulose, acetate butyrate cellulose, cellophane; polyethylene terephthalate resin (PET), polybutylene terephthalate resin, polyethylene naphthalate-isophthalate copolymer resin, polyester Polyester resins such as thermoplastic elastomers; low density polyethylene resins (including linear low density polyethylene resins), medium density polyethylene resins, high density polyethylene resins, ethylene α-olefin copolymers, polypropylene resins, polymethylpentene resins, polybutenes Polyolefin resins such as resins, ethylene-propylene copolymers, propylene-butene copolymers, olefinic thermoplastic elastomers or mixtures thereof; ) Acrylic resins such as methyl acrylate resin, poly (meth) ethyl acrylate resin, poly (meth) butyl acrylate resin; polyamide resin represented by nylon 6 or nylon 66; polystyrene resin; polycarbonate resin; polyarylate resin Or preferably a polyimide resin.

As the transparent substrate, it can be used alone or in the form of a mixture of two or more of the above-described plastic film and plastic sheet. From the viewpoint of flexibility, toughness, transparency, and the like, a cellulose resin, A polyester resin is more preferable, and triacetyl cellulose resin (TAC) and polyethylene terephthalate resin are more preferable.
Although there is no restriction | limiting in particular about the thickness of a transparent base material, Although it selects suitably according to a use, Usually, it is 5-130 micrometers, and when durability, handling property, etc. are considered, 10-100 micrometers is preferable.

(Hard coat layer)
Between the transparent substrate and the high refractive index layer, it is preferable to have a hard coat layer for the purpose of improving the scratch resistance of the antireflection film. Here, a hard coat means what shows hardness more than "H" in the pencil hardness test prescribed | regulated by JISK5600-5-4: 1999.
A hard-coat layer can be formed from the hard-coat layer coating liquid containing a curable resin composition, for example. Examples of the curable resin composition include a thermosetting resin composition and an ionizing radiation curable resin composition, and an ionizing radiation curable resin composition is preferable from the viewpoint of scratch resistance.

The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating.
Examples of the thermosetting resin include acrylic resin, urethane resin, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin. In the thermosetting resin composition, a curing agent is added to these curable resins as necessary.

The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as “ionizing radiation curable compound”). Examples of the ionizing radiation curable functional group include an ethylenically unsaturated bond group such as a (meth) acryloyl group, a vinyl group, and an allyl group, an epoxy group, and an oxetanyl group. As the ionizing radiation curable compound, a compound having an ethylenically unsaturated bond group is preferable, a compound having two or more ethylenic unsaturated bond groups is more preferable, and among them, having two or more ethylenically unsaturated bond groups, Polyfunctional (meth) acrylate compounds are more preferred. As the polyfunctional (meth) acrylate compound, any of a monomer and an oligomer can be used.
The ionizing radiation means an electromagnetic wave or a charged particle beam having an energy quantum capable of polymerizing or cross-linking molecules, and usually ultraviolet (UV) or electron beam (EB) is used. Electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams can also be used.

Among the polyfunctional (meth) acrylate compounds, bifunctional (meth) acrylate monomers include ethylene glycol di (meth) acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, 1,6-hexane. Examples thereof include diol diacrylate.
Examples of the tri- or higher functional (meth) acrylate monomer include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di Examples include pentaerythritol tetra (meth) acrylate and isocyanuric acid-modified tri (meth) acrylate.
The (meth) acrylate-based monomer may be modified by partially modifying the molecular skeleton, and is modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, or the like. Can also be used.

Moreover, examples of the polyfunctional (meth) acrylate oligomer include acrylate polymers such as urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate.
Urethane (meth) acrylate is obtained by reaction of polyhydric alcohol and organic diisocyanate with hydroxy (meth) acrylate, for example.
A preferable epoxy (meth) acrylate is a (meth) acrylate obtained by reacting (meth) acrylic acid with a tri- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin or the like. (Meth) acrylates obtained by reacting the above aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like with polybasic acids and (meth) acrylic acid, and bifunctional or higher functional aromatic epoxy resins, It is a (meth) acrylate obtained by reacting an alicyclic epoxy resin, an aliphatic epoxy resin or the like with a phenol and (meth) acrylic acid.
The ionizing radiation curable compounds can be used alone or in combination of two or more.

When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.
Examples of the photopolymerization initiator include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoylbenzoate, α-acyloxime ester, thioxanthones, and the like. These photopolymerization initiators preferably have a melting point of 100 ° C. or higher. By setting the melting point of the photopolymerization initiator to 100 ° C. or higher, the photopolymerization initiator remaining due to the heat of the transparent conductive film formation or the crystallization process is sublimated to prevent the low resistance of the transparent conductive film from being impaired. can do. The same applies when a photopolymerization initiator is used in a high refractive index layer and a low refractive index layer described later.
The photopolymerization accelerator can reduce polymerization inhibition by air during curing and increase the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. One or more selected may be mentioned.

The thickness of the hard coat layer is preferably in the range of 0.1 to 100 μm, and more preferably in the range of 0.8 to 20 μm. If the thickness of the hard coat layer is within the above range, sufficient hard coat performance can be obtained, and it is difficult to break without occurrence of cracks or the like with respect to external impact.
The thicknesses of the hard coat layer and the high refractive index layer and the low refractive index layer, which will be described later, are measured using, for example, a scanning electron microscope (SEM), a transmission electron microscope (TEM), or a scanning transmission electron microscope (STEM). The thickness at 20 locations can be measured from the photographed cross-sectional image and calculated from the average value of the 20 locations. When the film thickness to be measured is on the order of μm, it is preferable to use SEM, and when it is on the order of nm, it is preferable to use TEM or STEM. In the case of SEM, the acceleration voltage is preferably 1 to 10 kV and the magnification is preferably 1000 to 7000 times. In the case of TEM or STEM, the acceleration voltage is preferably 10 to 30 kV and the magnification is preferably 50,000 to 300,000 times.

  The refractive index of the hard coat layer is preferably smaller than the refractive index of the high refractive index layer described later, more preferably 1.45 to 1.70, and still more preferably 1.45 to 1.60. . If the refractive index of the hard coat layer is within such a range, the hard coat layer has a role as a middle refractive index layer, and the hard coat layer (medium refractive index layer), the high refractive index layer, and the low refractive index layer. Since the interference action by the three layers is possible, it is preferable in that the above-described various conditions are easily satisfied. From the viewpoint of suppressing interference fringes, it is preferable to reduce the difference between the refractive index of the hard coat layer and the refractive index of the transparent substrate.

Examples of means for imparting a role as a medium refractive index layer to the hard coat layer include a means for blending a resin having a high refractive index in the hard coat layer coating liquid and a means for blending particles having a high refractive index. When particles having a high refractive index are blended, whitening or coating defects may occur due to aggregation of the particles, so the former means (blending a resin having a high refractive index) is preferable.
Examples of the resin having a high refractive index include those obtained by introducing a sulfur-containing group, an aromatic ring, or the like into the thermosetting resin or ionizing radiation-curable compound described above. As the particles having a high refractive index, the same particles as those used for the high refractive index layer described later can be used.

  The refractive index of the hard coat layer, the high refractive index layer and the low refractive index layer, which will be described later, is, for example, a reflection spectrum measured by a reflection photometer and a reflection spectrum calculated from an optical model of a multilayer thin film using a Fresnel coefficient. And can be calculated by fitting.

  The hard coat layer is prepared by adjusting the coating liquid for forming the hard coat layer by using the curable resin composition described above, additives such as an ultraviolet absorber and a leveling agent, and a diluting solvent, which are blended as necessary. It can be formed by coating on a material by a conventionally known coating method, drying, and curing by irradiation with ionizing radiation as required.

(High refractive index layer)
The high refractive index layer can be formed from, for example, a high refractive index layer coating solution containing a curable resin composition and high refractive index particles.
The high refractive index layer preferably has a high refractive index from the viewpoint of making the antireflection film have a very low reflectance. However, in order to increase the refractive index, a large amount of high refractive index particles are required. Aggregates and causes whitening. For this reason, the refractive index is preferably 1.55 to 1.85, more preferably 1.56 to 1.70.
Further, the thickness of the high refractive index layer is preferably 200 nm or less, and more preferably 50 to 180 nm. In addition, when a high refractive index layer consists of 2 layer structure mentioned later, it is preferable that the total thickness of 2 layers satisfy | fills the said value.
The high refractive index layer may be formed from a plurality of layers satisfying the above refractive index range, but from the viewpoint of cost effectiveness, two or less layers are preferable, and a single layer is more preferable.

As high refractive index particles, antimony pentoxide (1.79), zinc oxide (1.90), titanium oxide (2.3 to 2.7), cerium oxide (1.95), tin-doped indium oxide (1. 95 to 2.00), antimony-doped tin oxide (1.75 to 1.85), yttrium oxide (1.87), zirconium oxide (2.10), and the like. In addition, the inside of the said parenthesis shows the refractive index of the material of each particle.
Among these high refractive index particles, those having a refractive index of more than 2.0 are preferable from the viewpoint of achieving the above-mentioned preferable refractive index with a small amount of addition. Further, conductive high refractive index particles such as antimony pentoxide, tin-doped indium oxide (ITO), and antimony-doped tin oxide (ATO) have free electrons whose plasma frequency is in the near infrared region, and the free electrons Due to the plasma oscillation, part of the light in the visible light region is also absorbed or reflected, and it may be difficult to suppress the color. For this reason, the high refractive index particles are preferably non-conductive.
From the above, among the high refractive index particles exemplified above, titanium oxide and zirconium oxide are suitable, and zirconium oxide is most suitable from the viewpoint of high durability stability such as light resistance. In addition, when it is desired to impart antistatic properties to the antireflection film, it is preferable that the high refractive index layer has a two-layer structure as described later and that one layer contains conductive high refractive index particles.

The average particle diameter of the primary particles of the high refractive index particles is preferably 5 to 200 nm, more preferably 5 to 100 nm, and further preferably 10 to 80 nm.
The average particle diameter of the primary particles of the high refractive index particles and the low refractive index particles described later can be calculated by the following operations (1) to (3).
(1) A surface image of SEM, TEM, or STEM is taken for the particles themselves or those obtained by applying and drying a dispersion of particles on a transparent substrate.
(2) Ten arbitrary particles are extracted from the surface image, the major axis and minor axis of each particle are measured, and the particle diameter of each particle is calculated from the average of the major axis and minor axis. The major axis is the longest diameter on the screen, and the minor axis is the distance between two points where a line segment perpendicular to the midpoint of the line segment constituting the major axis is drawn and the perpendicular line segment intersects the particle. Shall.
(3) The same operation was performed five times in the imaging of another screen of the same sample, and the value obtained from the number average of the particle diameters of a total of 50 particles was defined as the average particle diameter.
In calculating the average particle diameter of the particles, it is preferable to use SEM when the average particle diameter to be calculated is on the order of μm, and it is preferable to use TEM or STEM when the average particle diameter to be calculated is on the order of nm. . In the case of SEM, the acceleration voltage is preferably 1 to 10 kV and the magnification is preferably 1000 to 7000 times. In the case of TEM or STEM, the acceleration voltage is preferably 10 to 30 kV and the magnification is preferably 50,000 to 300,000 times.

  The content of the high refractive index particles is preferably 30 to 400 parts by mass with respect to 100 parts by mass of the curable resin composition, from the viewpoint of the balance between increasing the refractive index, suppressing tint, and suppressing whitening, and 50 More preferably, it is -200 mass parts, More preferably, it is 80-150 mass parts.

  The high refractive index layer is preferably dispersed and stabilized in order to suppress excessive aggregation of the high refractive particles. As a means for stabilizing the dispersion, for example, a means for adding another high refractive index particle having a smaller surface charge than that of the high refractive particle serving as a base to the base may be mentioned. According to this means, it is possible to suppress the high refractive index particles serving as the base from appropriately gathering around the other high refractive index particles and excessively aggregating the high refractive particles serving as the base. Further, as another means for stabilizing the dispersion, there may be mentioned means for using a surface treated as high refractive index particles or adding a dispersing agent to the high refractive index layer coating solution.

As the curable resin composition for forming the high refractive index layer, the same as those exemplified for the hard coat layer can be used, and an ionizing radiation curable resin composition is suitable.
Moreover, in order to obtain the refractive index mentioned above without making the addition amount of high refractive index particles excessive, it is preferable to use a curable resin composition having a high refractive index. The refractive index of the curable resin composition is preferably about 1.54 to 1.70.

The high refractive index layer may have a two-layer configuration of a high refractive index layer (A) located on the hard coat layer side and a high refractive index layer (B) located on the low refractive index layer side. At that time, it is preferable to make the refractive index of the high refractive index layer (B) higher than the refractive index of the high refractive index layer (A). By configuring the high refractive index layer as described above, the refractive index difference with the low refractive index layer can be increased, the reflectance can be lowered, and the refractive index difference between the high refractive index layer and the hard coat layer can be reduced, thereby interfering with the interference. Generation of fringes can be suppressed.
When the high refractive index layer has two layers, the refractive index of the high refractive index layer (A) is 1.55 to 1.70, and the refractive index of the high refractive index layer (B) is 1.60 to 1.85. Preferably there is.
Further, in the above two-layer configuration, one of the high refractive index layer (A) and the high refractive index layer (B) contains conductive high refractive index particles, and the other contains nonconductive high refractive index particles. And, it is preferable that [the thickness of the layer containing conductive high refractive index particles <the thickness of the layer containing nonconductive high refractive index particles]. By setting it as the said structure, antistatic property can be provided, suppressing the addition amount of electroconductive high refractive index particle | grains which can cause a color tint. Further, the conductive high refractive index particles are preferable in that they can be networked in the layer to impart antistatic properties with a small addition amount, and as a result, color and whitening can be suppressed.

  The high refractive index layer is prepared by adjusting the coating liquid for forming a high refractive index layer with a high refractive index particle, a curable resin composition, an additive such as an ultraviolet absorber or a leveling agent and a diluent solvent, if necessary. The coating solution can be formed on the hard coat layer by coating, drying, and curing by irradiating with ionizing radiation as necessary.

(Low refractive index layer)
The low refractive index layer is a layer provided on the high refractive index layer.
The low refractive index layer preferably has a refractive index of 1.26 to 1.40, more preferably 1.28 to 1.38, in order to make the antireflection film have an extremely low reflectance. More preferably, it is 30 to 1.32.
The lower the refractive index of the low refractive index layer, the lower the refractive index of the antireflection film without increasing the refractive index of the high refractive index layer. On the other hand, if the refractive index of the low refractive index layer is too low, the strength of the low refractive index layer tends to decrease. Therefore, by setting the refractive index of the low refractive index layer within the above range, the amount of the high refractive index particles added to the high refractive index layer can be suppressed while maintaining the strength of the low refractive index layer. Is preferable in that it leads to suppression.
The thickness of the low refractive index layer is preferably 80 to 120 nm, more preferably 85 to 110 nm, and still more preferably 90 to 105 nm.
The low refractive index layer may be formed from a plurality of layers satisfying the above refractive index range, but from the viewpoint of cost effectiveness, two or less layers are preferable, and a single layer is more preferable.

Methods for forming the low refractive index layer can be broadly classified into wet methods and dry methods. As the wet method, a method of forming by a sol-gel method using a metal alkoxide, a method of forming by applying a low refractive index resin such as a fluororesin, and a low low refractive index particle in a resin composition. A technique of coating and forming a coating solution for forming a refractive index layer is exemplified. Examples of the dry method include a method in which particles having a desired refractive index are selected from low-refractive-index particles described later and formed by physical vapor deposition or chemical vapor deposition.
The wet method is excellent in terms of production efficiency. In the present invention, among the wet methods, the wet method is preferably formed by a coating solution for forming a low refractive index layer in which low refractive index particles are contained in a resin composition.

  The low refractive index particles are preferably used for the purpose of lowering the refractive index, that is, for the purpose of improving the antireflection properties, and are used without limitation whether they are inorganic or organic such as silica or magnesium fluoride. However, from the viewpoint of further improving the antireflection characteristics and ensuring good surface hardness, particles having a structure having voids themselves are preferably used.

  A particle having a structure having a void itself has a fine void inside, and is filled with a gas such as air having a refractive index of 1.0, so that its own refractive index is low. It has become. Examples of such particles having voids include inorganic or organic porous particles, hollow particles, and the like. For example, porous polymer particles using porous silica, hollow silica particles, acrylic resin, or the like. And hollow polymer particles. As inorganic particles, silica particles having voids prepared by using the technology disclosed in Japanese Patent Application Laid-Open No. 2001-233611 are used, and as organic particles, technology disclosed in Japanese Patent Application Laid-Open No. 2002-80503. As a preferred example, hollow polymer particles prepared using Silica having voids as described above or porous silica has a refractive index in the range of 1.18 to 1.44, and a refractive index higher than that of general silica particles having a refractive index of about 1.45. Is low from the viewpoint of reducing the refractive index of the low refractive index layer.

  The hollow silica particles are particles having a function of lowering the refractive index while maintaining the coating strength of the low refractive index layer. The hollow silica particles used in the present invention are silica particles having a structure having a cavity inside. The hollow silica particles are silica particles whose refractive index decreases in inverse proportion to the occupancy of the internal cavities as compared with the original refractive index of silica particles (refractive index n = 1.45 or so). For this reason, the refractive index of the hollow silica particles as a whole is 1.18 to 1.44.

  The hollow silica particles are not particularly limited, and are, for example, particles that have an outer shell and are porous or hollow inside, and are disclosed in JP-A-6-330606, JP-A-7-013137, and JP-A-7. -133105 and the silica particle prepared using the technique currently disclosed by Unexamined-Japanese-Patent No. 2001-233611.

  The average particle diameter of the primary particles of the low refractive index particles is preferably 5 to 200 nm, more preferably 5 to 100 nm, and further preferably 10 to 80 nm. If the average particle diameter of the primary particles is within the above range, the transparency of the low refractive index layer is not impaired, and a good dispersion state of the particles can be obtained. In particular, when hollow particles are used as the low refractive index particles and the average particle diameter of the hollow particles is 70 to 80 nm, the refractive index is lowered by increasing the porosity while maintaining the thickness of the outer shell that does not cause insufficient strength. It is preferable in that it is excellent in balance with the thickness (about 100 nm) of an ideal low refractive index layer for reducing the reflectance.

  The low refractive index particles used in the present invention are preferably surface-treated. As the surface treatment of the low refractive index particles, a surface treatment using a silane coupling agent is more preferable, and among these, a surface treatment using a silane coupling agent having a (meth) acryloyl group is preferably performed. By applying surface treatment to the low refractive index particles, the affinity with the binder resin described later is improved, the dispersion of the particles becomes uniform, and the particles are less likely to agglomerate. The decrease in the transparency of the refractive index layer, the applicability of the composition for forming a low refractive index layer, and the decrease in the coating strength of the composition are suppressed.

  In addition, when the silane coupling agent has a (meth) acryloyl group, the silane coupling agent has ionizing radiation curability, and therefore easily reacts with a binder resin described later. Therefore, the composition for forming a low refractive index layer In the coating film, the low refractive index particles are satisfactorily fixed to the binder resin. That is, the low refractive index particles have a function as a crosslinking agent in the binder resin. Thereby, the tightening effect of the whole coating film is obtained, and it is possible to impart excellent surface hardness to the low refractive index layer while leaving the flexibility inherent to the binder resin. Therefore, since the low refractive index layer is deformed by utilizing its own flexibility, it has the ability to absorb and restore external impacts, so that the generation of scratches is suppressed and the surface hardness is excellent with excellent scratch resistance. It will have.

  Examples of the silane coupling agent preferably used in the surface treatment of the low refractive index particles include 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, and 3- (meth) acryloxypropyl. Examples thereof include methyldimethoxysilane, 3- (meth) acryloxypropylmethyldiethoxysilane, 2- (meth) acryloxypropyltrimethoxysilane, 2- (meth) acryloxypropyltriethoxysilane and the like.

The content of the low refractive index particles in the low refractive index layer is preferably 10 to 250 parts by mass, more preferably 50 to 200 parts by mass, and even more preferably 100 to 180 parts by mass with respect to 100 parts by mass of the resin of the low refractive index layer. preferable. If the content of the low refractive index particles is within the above range, good antireflection characteristics and surface hardness can be obtained.
Further, the ratio of the hollow particles and / or the porous particles in all the low refractive index particles contained in the low refractive index layer is preferably 70% by mass or more, more preferably 80% by mass or more, and further 80 to 95% by mass. preferable.

As a resin composition contained in the coating solution for forming a low refractive index layer, first, a curable resin composition is exemplified. As a curable resin composition, the thing similar to what was illustrated by the hard-coat layer can be used, and an ionizing radiation curable resin composition is suitable.
Further, as the resin composition, a fluorine-containing polymer or a fluorine monomer which itself exhibits a low refractive index property is also preferably used. The fluorine-containing polymer is a polymer of a polymerizable compound containing at least a fluorine atom in the molecule, and is preferable in that it can impart antifouling property and slipperiness. The fluoropolymer preferably has a reactive group in the molecule and functions as a curable resin composition, and has an ionizing radiation curable reactive group and functions as an ionizing radiation curable resin composition. More preferred.

  As the fluorine-containing polymer, not only repels dirt on the surface of the low refractive index layer, but also preferably contains silicon together with fluorine in order to impart wiping properties of the repelled dirt. For example, the copolymer contains a silicone component. Preferred is a silicone-containing vinylidene fluoride copolymer. Examples of silicone components in this case include (poly) dimethylsiloxane, (poly) diethylsiloxane, (poly) diphenylsiloxane, (poly) methylphenylsiloxane, alkyl-modified (poly) dimethylsiloxane, azo group-containing (poly) dimethylsiloxane, , Dimethyl silicone, phenylmethyl silicone, alkyl aralkyl modified silicone, fluorosilicone, polyether modified silicone, fatty acid ester modified silicone, methyl hydrogen silicone, silanol group containing silicone, alkoxy group containing silicone, phenol group containing silicone, methacryl modified silicone, Acrylic modified silicone, amino modified silicone, carboxylic acid modified silicone, carbinol modified silicone, epoxy modified silicone, mercapto modified silicone Corn, fluorine-modified silicones, polyether-modified silicone, and the like. Of these, those having a dimethylsiloxane structure are preferred.

  The low refractive index layer is prepared, for example, by adjusting the coating solution for forming a low refractive index layer with low refractive index particles, a resin composition, additives such as an ultraviolet absorber and a leveling agent, and a diluent solvent, if necessary. The coating liquid can be formed on the high refractive index layer by coating and drying by a conventionally known coating method, and curing by irradiation with ionizing radiation as necessary.

(Physical properties of antireflection film)
The antireflection film preferably has a total light transmittance (JIS K7361-1: 1997) of 90% or more, and more preferably 92% or more. In the antireflection film of the present invention, the haze (JISK7136: 2000) is preferably 1.0% or less, more preferably 0.5% or less, and further preferably 0.3% or less. preferable.
The light incident surface for measuring the total light transmittance and haze is on the transparent substrate side.

The arithmetic average roughness Ra (JIS B0601: 1994) of the surface of the antireflection film (the surface on the low refractive index layer side) is preferably 10 nm or less, and more preferably 1 to 8 nm. The ten-point average roughness Rz (JIS B0601: 1994) of the surface of the antireflection film (the surface on the low refractive index layer side) is preferably 160 nm or less, and more preferably 50 to 155 nm.
When Ra and Rz are within the above ranges, the surface is smooth and the scratch resistance is improved.

  The above-described antireflection film of the present invention is excellent in a narrow range of color uniformity. In particular, a small display device having a screen size of a diagonal of 38.1 cm or less (particularly, a display device having a length-to-width ratio (vertical length / horizontal length) of 1.50 to 1.80) and a pixel number of When the antireflection film of the present invention is used for a display device having a resolution of so-called 4K resolution of 3840 × 2160 pixels or more, the effect can be easily exhibited.

[Display device]
In the display device of the present invention, the above-described antireflection film of the present invention is arranged on a display element such that the transparent substrate side of the antireflection film faces the display element side.
Examples of the display element constituting the display device include a liquid crystal display element, a plasma display element, and an organic EL display element.
The specific configuration of the display element is not particularly limited. For example, in the case of a liquid crystal display element, the liquid crystal display element has a basic structure having a lower glass substrate, a lower transparent electrode, a liquid crystal layer, an upper transparent electrode, a color filter, and an upper glass substrate in this order. The upper transparent electrode is patterned with high density.

  The size of the display device is not particularly limited, but a small display device having a diagonal size of 38.1 cm or less where importance is placed on color uniformity in a narrow range (particularly, the length ratio (vertical length / The display device (lateral length) of 1.50 to 1.80 is preferable in that the effect of the present invention is easily exhibited.

The display element preferably has a so-called 4K resolution or higher resolution in which the number of pixels is 3840 × 2160 pixels or higher. An ultra-high-definition display element having a resolution of 4K or higher is preferable in that it has a small amount of light per pixel, is easily affected by color, and easily exhibits the effects of the present invention.
Note that examples of the 4K resolution display element include a display element having 3840 × 2160 pixels and a display element having 4096 × 2160 pixels.

The display device of the present invention may have a touch panel on a display element, and an antireflection film may be disposed on the touch panel. In this embodiment as well, it is necessary to dispose the antireflection film so that the transparent substrate side faces the display element side.
Examples of the touch panel include a capacitive touch panel, a resistive touch panel, an optical touch panel, an ultrasonic touch panel, and an electromagnetic induction touch panel.

A resistive touch panel has a basic configuration in which a conductive film of a pair of upper and lower transparent substrates having a conductive film is arranged with a spacer so as to face each other, and a circuit is connected to the basic configuration. is there.
The capacitive touch panel includes a surface type and a projection type, and a projection type is often used. A projected capacitive touch panel is formed by connecting a circuit to a basic configuration in which an X-axis electrode and a Y-axis electrode orthogonal to the X electrode are arranged via an insulator. The basic structure will be described more specifically. (1) A mode in which X electrodes and Y electrodes are formed on separate surfaces on a single transparent substrate, (2) X electrodes, insulator layers, Y on a transparent substrate An embodiment in which the electrodes are formed in this order, (3) an embodiment in which an X electrode is formed on a transparent substrate, a Y electrode is formed on another transparent substrate, and laminated via an adhesive layer or the like are included. Moreover, the aspect which laminate | stacks another transparent substrate in these basic aspects is mentioned.

[Selection method of antireflection film]
The method for selecting the antireflection film of the present invention is such that the antireflection film having a high refractive index layer and a low refractive index layer on the transparent substrate has a surface opposite to the high refractive index layer side of the transparent substrate. A sample in which a black plate is bonded via a transparent adhesive is prepared, and the L ^* value, a ^* value, and b ^* value of the Lab color system measured from the sample satisfy the following condition (1) It is what.
<Condition (1)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, the ^{L *} value at each incident angle, calculates the square root SQ sum of squares of ^{a *} and ^{b *} values. When the difference SQ _di of the square root of the sum of squares of the L ^* value, a ^* value, and b ^* value between each measurement is calculated, the maximum value of SQ _di is 0.25 or less.

  In the method for selecting an antireflection film of the present invention, it is preferable that one or more selected from the above-described conditions (2) to (4) are used as the determination conditions.

The antireflection film to be selected in the present invention may have a layer other than the high refractive index layer and the low refractive index layer on the transparent substrate. For example, you may have a hard-coat layer between a transparent base material and a high refractive index layer.
Embodiments of the transparent base material, the high refractive index layer, the low refractive index layer, and the hard coat layer provided as necessary according to the selection method of the antireflection film of the present invention are the antireflection film of the present invention. The transparent substrate, the high refractive index layer, the low refractive index layer, and the hard coat layer are the same as in the embodiment.

  According to the method for selecting an antireflection film of the present invention, an antireflection film excellent in a narrow range of color uniformity can be accurately selected, and the quality of the antireflection film can be standardized.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.

1. Physical properties and evaluation The following measurements and evaluations were performed on the antireflection films obtained in Examples , Reference Examples and Comparative Examples. The results are shown in Tables 1 and 2.
1-1. The L ^* value, a ^* value, and b ^* value of the Lab color system of the antireflection film are coated with a transparent adhesive (refractive index 1.49) on the surface of the antireflection film opposite to the high refractive index layer side. ) Through which a black plate (refractive index: 1.49) was bonded. The incident angle of light perpendicularly incident on the surface of the prepared sample on the low refractive index layer side is 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 45 degrees. The L ^* value, a ^* value and b ^* value of the Lab color system of specular reflection light were measured. Table 1 shows the square root SQ of the sum of squares of the L ^* value, a ^* value, and b ^* value at each incident angle. Further, the numerical values of the above conditions (1) to (3) were calculated from the square root SQ of the square sum of the L ^* value, a ^* value, and b ^* value at each incident angle. The results are shown in Table 2.
The measuring device for L ^* value, a ^* value, and b ^* value uses a spectrophotometer (trade name: V-7100, manufactured by JASCO Corporation), the viewing angle is 2 degrees, the light source is D65, and the measurement wavelength is 380. ˜780 nm was taken as 0.5 nm interval.

1-2. Luminous reflectance Y value of the antireflection film The incident angle of light incident perpendicularly to the surface on the low refractive index layer side of the sample prepared in 1-1 above is 0 degree, and light is incident on the sample at an incident angle of 5 degrees Was incident, the luminous reflectance Y value of the regular reflection light of the incident light was measured.
A spectrophotometer (manufactured by Shimadzu Corporation, trade name: UV-2450) was used as a measuring device for the luminous reflectance Y value, the viewing angle was 2 degrees, the light source was D65, and the measurement wavelength was 380 to 780 nm. The interval was 5 nm.

1-3. Evaluation of anti-reflection performance of anti-reflection film An anti-reflection film is installed on a liquid crystal display element having 3840 × 2160 pixels so that the surface of the anti-reflection film faces the liquid crystal display element side. A simulated liquid crystal display device was produced. In a bright room environment, without displaying an image on the display element, the image of the observer himself is reflected near the center of the surface (low refractive index layer) of the simulated liquid crystal display device from the vertical direction of the simulated liquid crystal display device. It was observed visually.
As a result, “A” indicates that the reflected skin color of the viewer cannot be strongly recognized as “A”, and “B” indicates that the skin color of the reflected viewer can be slightly recognized.

1-4. Narrow range color uniformity of antireflection film The sample prepared in 1-1 above was cut to a size of 31.5 cm diagonal (18.2 cm long, 25.7 cm wide). A fluorescent lamp was reflected on the cut sample in a bright room, and the color of the sample surface was visually observed from a position where regular reflection light could be confirmed. During the observation, the sample was moved directly below the fluorescent lamp so as to gradually change from vertical (0 degrees) to 20 degrees with respect to the fluorescent lamp.
Twenty people made this observation, and each person evaluated one sample with no spot where a sharp change in color was felt, and two samples with a spot where a sharp change in color was felt. The average score of 20 people is “A” when the average score is 1.25 or less, “B” when the score is more than 1.25 and less than 1.50, and “C” when the score is more than 1.50. .

2. Preparation of antireflection film [ Reference Example 1]
On a triacetyl cellulose film (refractive index: 1.49) having a thickness of 80 μm, a hard coat layer forming coating solution having the following formulation was applied, dried and irradiated with ultraviolet rays, having a thickness of 10 μm, a refractive index of 1.51, and a pencil hardness of 2H). A hard coat layer was formed. Next, a coating solution for forming a high refractive index layer having the following formulation was applied on the hard coat layer, dried and irradiated with ultraviolet rays to form a high refractive index layer having a thickness of 150 nm and a refractive index of 1.63). Next, a coating solution for forming a low refractive index layer having the following formulation is applied on the high refractive index layer, dried and irradiated with ultraviolet rays to form a low refractive index layer having a thickness of 100 nm and a refractive index of 1.30), and an antireflection film. Got.

<Preparation of hard coat layer forming coating solution>
1 photopolymerization initiator (BASF, Irgacure 127, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one) .6 parts by mass and 58.3 parts by mass of a diluting solvent (methyl isobutyl ketone / cyclohexanone = 8/2) were added and stirred until there was no undissolved residue. 40 mass parts of photocuring resin (Arakawa Chemical Co., Ltd. make, beam set 577) was put here, and it stirred until it was not melt | dissolved. Finally, 0.1 parts by weight of a leveling agent (Daiichi Seika Kogyo Co., Ltd., Seika Beam 10-28 (MB)) was added and stirred to prepare a coating solution for forming a hard coat layer.

<Preparation of coating solution for forming a high refractive index layer>
Photopolymerization initiator (BASF, Irgacure 127) 0.1 parts by mass, dilute solvent (methyl isobutyl ketone / cyclohexanone / methyl ethyl ketone = 4/2/4) was added 92.6 parts by mass, and the mixture was stirred until there was no undissolved residue. . 1.25 mass parts of photocuring resin (Arakawa Chemical Co., Ltd. beam set 577) was put here, and it stirred until there was no undissolved residue. Furthermore, 6 parts by mass of zirconium oxide (Sumitomo Osaka Cement Co., Ltd., MZ-230X, solid content 32.5% by mass, average primary particle size 15-50 nm), leveling agent (Daiichi Seika Kogyo Co., Ltd., Seika Beam 10-28 ( MB)) 0.05 parts by mass were added and stirred to prepare a coating solution for forming a high refractive index layer.

<Preparation of coating solution for forming low refractive index layer>
A photopolymerization initiator (BASF, Irgacure 127) 0.2 parts by mass and a diluting solvent (MIBK / AN = 7/3) 91.1 parts by mass were added and stirred until there was no undissolved residue. Here, 1.0 part by mass of photo-curing resin (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30), 7.6 parts by mass of hollow silica particles (solid content 20% by mass, average primary particle size 60 nm), leveling agent (large Nissei Kagaku Kogyo Co., Ltd., Seika Beam 10-28 (MB)) 0.1 parts by mass were added and stirred to prepare a coating solution for forming a low refractive index layer.

[Example 1 ]
The high refractive index layer of Reference Example 1 has a two-layer structure, and zirconium oxide of the coating liquid for forming the high refractive index layer of Reference Example 1 is used as antimony pentoxide (A) as the coating liquid for the high refractive index layer (A) on the hard coat layer side. The solid content of 40% by mass) (refractive index 1.58 after change) was used, the thickness was 50 nm, and the coating liquid for the high refractive index layer (B) on the low refractive index layer side was high as in Reference Example 1. An antireflection film was obtained in the same manner as in Reference Example 1 except that the refractive index layer forming coating solution was used and the thickness was changed to 105 nm.

[ Reference Example 2 ]
The high refractive index layer (B) of Example 1 was not formed, and with respect to the high refractive index layer (A), 4.25 parts by mass of the photocurable resin of the coating solution, antimony pentoxide was antimony-doped tin oxide (solid content 45) % By weight), and the one changed to 3 parts by mass (refractive index after change 1.56), the film thickness was changed to 160 nm, and the photocurable resin of the coating liquid was changed to 3 for the low refractive index layer. .1 part by mass, the amount of hollow silica particles was changed to 5.5 parts by mass (refractive index after change of 1.38), and the thickness was changed to 90 nm, and an antireflection film was obtained in the same manner as in Example 1 . .

[Comparative Example 1]
The photo-curing resin of the coating liquid for forming the hard coat layer in Reference Example 1 was changed to 20 parts by mass, and 20 parts by mass of a high refractive index resin (manufactured by DIC Corporation, Polylite RX-4800) was added (after change). The antireflection film was obtained in the same manner as in Reference Example 1 except for the refractive index of 1.54).

[Comparative Example 2]
The high refractive index layer (A) on the hard coat layer side in Example 1 was changed from antimony pentoxide to ampmon-doped tin oxide (refractive index 1.59 after the change), and the high refractive index layer (A) An antireflection film was obtained in the same manner as in Example 1 except that the thickness of was changed to 70 nm.

[Comparative Example 3]
Comparative Example 2 was the same as Comparative Example 2, except that the thickness of the high refractive index layer (A) on the hard coat layer side was changed to 60 nm and the thickness of the high refractive index layer (B) on the low refractive index layer side was changed to 120 nm. Thus, an antireflection film was obtained.

As is clear from the results in Table 2, it can be seen that the antireflection films of Example 1 and Reference Examples 1 and 2 satisfying the condition (1) are excellent in color uniformity in a narrow range.
On the other hand, it turns out that the antireflection film of Comparative Examples 1-3 which does not satisfy | fill conditions (1) cannot satisfy the color uniformity of a narrow range.

  The antireflection film and display device of the present invention are useful in that they are excellent in a narrow range of color uniformity.

Claims (11)

High refractive index layer on a transparent substrate, and a antireflection film having a low refractive index layer provided on the high refractive index layer,
The high refractive index layer has a two-layer configuration,
The antireflection film is an L ^* value of the Lab color system measured from a sample in which a black plate is bonded to the surface of the antireflection film opposite to the high refractive index layer side of the transparent base material via a transparent adhesive. , A ^* value and b ^* value satisfy the following condition (1).
<Condition (1)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, the ^{L *} value at each incident angle, calculates the square root SQ sum of squares of ^{a *} and ^{b *} values. When the difference SQ _di of the square root of the sum of squares of the L ^* value, a ^* value, and b ^* value between each measurement is calculated, the maximum value of SQ _di is 0.25 or less. The antireflection film according to claim 1, wherein the L ^* value, a ^* value, and b ^* value of the Lab color system measured from the sample satisfy the following condition (2).
<Condition (2)>
The incident angle of light perpendicularly incident on the surface of the low refractive index layer side of the sample is set to 0 degree, and light is incident on the sample at an interval of 25 degrees from an incident angle of 25 degrees to 45 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, to calculate the square root SQ of the sum of the squares of the ^{L *} value, ^{a *} and ^{b *} values at each incident angle, further, the When the cumulative value SQ _25-45 of the square root SQ of the sum of squares is calculated, the cumulative value SQ _25-45 is 20.00 or more. Lab color system L measured from the sample ^* Value, a ^* Value and b ^* The antireflection film according to claim 1 or 2, wherein the value satisfies the following condition (3).
<Condition (3)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. Light Lab color system L ^* Value, a ^* Value and b ^* Measure the value, L at each incident angle ^* Value, a ^* Value and b ^* The square root SQ of the square sum of the values is calculated, and the cumulative value SQ of the square root SQ of the square sum _5-20 When the cumulative value SQ is calculated. _5-20 Is 12.00 or less. The antireflection film according to claim 1 comprising a hard coat layer between the high refractive index layer and the transparent substrate. The antireflection film according to claim 1, wherein one of the high refractive index layers includes conductive high refractive index particles, and the other includes nonconductive high refractive index particles. Among the high refractive index layers, the refractive index of the layer located on the low refractive index layer side is 1.60 to 1.85, and the refractive index of the layer located on the transparent substrate side is 1.55 to 1. 70, and the thickness of the high refractive index layer is 200 nm or less,
6. The antireflection film according to claim 1, wherein the low refractive index layer has a refractive index of 1.26 to 1.40, and the low refractive index layer has a thickness of 80 to 120 nm. A display device in which the antireflection film according to any one of claims 1 to 6 is arranged on a display element so that the transparent substrate side of the antireflection film faces the display element. The display device according to claim 7 , further comprising a touch panel on the display element, wherein the antireflection film is disposed on the touch panel. The display device according to claim 7 or 8 , wherein a screen size of the display device is a diagonal of 38.1 cm or less. Display device according to any one of claims 7-9 number of pixels is 3840 × 2160 pixels or more of the display device. On a transparent substrate, a two-layer high-refractive index layer of the structure, and a transparent adhesive on a surface opposite to the high refractive index layer side of the transparent substrate of the antireflective film comprising a low refractive index layer A sample in which a black plate is bonded to the sample, and the L ^* value, a ^* value, and b ^* value of the Lab color system measured from the sample satisfy the following condition (1). Prevention film selection method.
<Condition (1)>
The incident angle of light perpendicularly incident on the surface of the sample on the low refractive index layer side is set to 0 degree, and light is incident on the sample at intervals of 5 degrees from an incident angle of 5 degrees to 20 degrees, and regular reflection of the incident light is performed. Lab color system of ^{L *} value of light, ^{a *} and ^{b *} values were measured, the ^{L *} value at each incident angle, calculates the square root SQ sum of squares of ^{a *} and ^{b *} values. When the difference SQ _di of the square root of the sum of squares of the L ^* value, a ^* value, and b ^* value between each measurement is calculated, the maximum value of SQ _di is 0.25 or less.