JP2023047651A - Optical film set and image display device - Google Patents

Abstract

To provide an optical film set capable of ensuring image clarity and suppressing reflection and white blur of an image display device having a cover window thereon via an air layer, and to provide an image display device using such optical film set.SOLUTION: An optical film set 100 disclosed herein comprises a first optical film 10 and a second optical film 20. The first optical film 10 comprises a first transparent film base material 11, a first hard coat layer 12, and a first anti-reflection layer 13 arranged in the described order. The second optical film 20 comprises a second transparent film base material 21, a second hard coat layer 22, and a second anti-reflection layer 23 arranged in the described order. The first optical film 10 has a haze in a range of 15% to 40%, inclusive. The second optical film 20 has a haze of 30% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical film set and an image display device.

Liquid crystal display devices and organic EL display devices are widely used as various image display devices such as smartphones, car navigation devices, personal computer monitors, and televisions. In such an image display device, a cover window made of a transparent resin plate, a glass plate, or the like is sometimes provided on the viewing side of the image display cell (more specifically, a liquid crystal cell, an organic EL cell, or the like).

For example, Patent Literature 1 describes a cover window that protects the viewing side (display surface) of an image display cell. The cover window described in Patent Document 1 has a decorative portion formed on the peripheral edge of the display surface side surface, and is attached to the display surface via a double-faced adhesive sheet having the same shape as the decorative portion. Therefore, in the image display device of Patent Document 1, an air layer exists between the cover window and the display surface.

JP-A-2003-255847

In the image display device, if there is an air layer between the cover window and the display surface, the reflection of light at the interface of the air layer causes reflection of outside light, which tends to reduce the visibility of the screen. In some cases, an anti-glare film is placed on the display surface in order to suppress deterioration in visibility due to the glare. However, when the anti-glare film is placed on the display surface, a phenomenon called "white blur" may occur in which the image becomes whitish due to the diffusion of light when used in a bright environment. Further, when an antiglare film is placed on the display surface, the sharpness of an image with a white background (hereinafter sometimes referred to as "image sharpness") may deteriorate. As described above, in an image display device in which a cover window is provided via an air layer, it is difficult to suppress reflection and white blur while ensuring image clarity.

The present invention has been made in view of the above problems, and its object is to be able to suppress reflection and white blur while ensuring image clarity in an image display device in which a cover window is provided via an air layer. An object of the present invention is to provide an optical film set and an image display device using the optical film set.

An optical film set according to the present invention comprises a first optical film arranged on the viewing side of an image display cell via a cover window, and a second optical film arranged on the image display cell side of the cover window via an air layer. and an optical film. The first optical film has a first transparent film substrate, a first hard coat layer and a first antireflection layer in this order. The second optical film has a second transparent film substrate, a second hard coat layer and a second antireflection layer in this order. The haze of the first optical film is 15% or more and 40% or less. A haze of the second optical film is 30% or less.

In one embodiment of the optical film set according to the present invention, the first optical film further includes a first pressure-sensitive adhesive layer disposed on the side opposite to the first hard coat layer side of the first transparent film base. have.

In one embodiment of the optical film set according to the present invention, the second optical film further has a polarizer arranged on the side opposite to the second hard coat layer side of the second transparent film base.

In one embodiment of the optical film set according to the present invention, the second optical film further has a second pressure-sensitive adhesive layer arranged on the opposite side of the polarizer to the second transparent film substrate side.

In one embodiment of the optical film set according to the present invention, the first hard coat layer contains a binder and particles having an average particle size of 1.0 μm or more and 8.0 μm or less.

An image display device according to the present invention includes an image display cell, a cover window arranged on the viewing side of the image display cell, and an optical film set according to the present invention. The first optical film of the optical film set is arranged on the viewing side of the cover window with the first antireflection layer facing the viewing side. The second optical film of the optical film set is arranged on the image display cell side of the cover window via an air layer, with the second antireflection layer facing the viewing side.

In one embodiment of the image display device according to the present invention, the air layer has a thickness of 0.1 mm or more and 2.0 mm or less.

According to the present invention, in an image display device provided with a cover window via an air layer, an optical film set capable of suppressing reflection and white blur while ensuring image clarity, and an image using the optical film set. A display device can be provided.

1 is a cross-sectional view showing an example of an optical film set according to the present invention; FIG. 1 is a cross-sectional view showing an example of a first optical film included in an optical film set according to the present invention; FIG. FIG. 4 is a cross-sectional view showing an example of a second optical film included in the optical film set according to the present invention; FIG. 4 is a cross-sectional view showing another example of the second optical film included in the optical film set according to the present invention; It is a sectional view showing an example of an image display device concerning the present invention.

Preferred embodiments of the present invention are described below. First, the terms used in this specification will be explained. "Average particle size" is the volume average particle size measured by the Coulter Counter method. "Number average primary particle size" is the circle equivalent diameter of 100 primary particles (Heywood diameter: primary particle size) measured using an electron microscope and image processing software (e.g., "ImageJ" manufactured by the National Institutes of Health). diameter of a circle having the same area as the projected area). "Refractive index" refers to the refractive index for light with a wavelength of 550 nm in an atmosphere at a temperature of 23°C. The "principal surface" of a layered product (more specifically, a transparent film substrate, a hard coat layer, an adhesive layer, a polarizer, a transparent protective film, a cover window, etc.) refers to a surface perpendicular to the thickness direction of the layered product. point to A "major component" of a material means the component, by weight, that is the most abundant component of that material. The thickness (film thickness) of each layer constituting the optical film is obtained by randomly selecting 10 measurement points from an image of a cross section of the layer cut in the thickness direction, and measuring the thickness of the selected 10 measurement points. is the arithmetic mean of 10 measurements obtained.

Hereinafter, compounds and derivatives thereof may be collectively referred to by adding "system" to the name of the compound. When the polymer name is expressed by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative. Acryl and methacryl may be collectively referred to as "(meth)acryl". Acryloyl and methacryloyl may be collectively referred to as "(meth)acryloyl". Acrylate and methacrylate may be collectively referred to as "(meth)acrylate".

In this specification, both solvent and dispersion medium are described as "solvent". In addition, the drawings referred to in the following description schematically show each component mainly for easy understanding, and the size, number, shape, etc. It may differ from the actual one due to the convenience of Also, for convenience of description, in the drawings described later, the same components as those in the drawings described earlier may be denoted by the same reference numerals, and the description thereof may be omitted.

<First Embodiment: Optical Film Set>
An optical film set according to a first embodiment of the present invention includes a first optical film arranged on the viewing side of an image display cell with a cover window interposed therebetween, and an optical film arranged on the image display cell side of the cover window with an air layer interposed therebetween. and a second optical film. The first optical film is a laminate having a first transparent film substrate, a first hard coat layer and a first antireflection layer in this order. The second optical film is a laminate having a second transparent film substrate, a second hard coat layer and a second antireflection layer in this order. The haze of the first optical film is preferably 15% or more and 40% or less. The haze of the second optical film is preferably 30% or less. Both the haze of the first optical film and the haze of the second optical film can be measured according to JIS K7136-2000.

The optical film set according to the first embodiment includes a first optical film having a specific haze range and a second and an optical film. As a result, the optical film set according to the first embodiment can suppress reflection and white blur while ensuring image clarity in an image display device.

In the first embodiment, the haze of the first optical film is preferably 18% or more, more preferably 20% or more, and more preferably 23% or more in order to further suppress reflection. More preferably, it is still more preferably 25% or more. Further, in the first embodiment, the haze of the first optical film is preferably 38% or less, more preferably 35% or less, in order to further suppress white blurring.

In the first embodiment, the haze of the second optical film is preferably 0.3% or more, more preferably 0.5% or more, in order to further suppress reflection. In the first embodiment, the haze of the second optical film is preferably 29% or less, more preferably 28% or less, in order to further suppress white blurring.

In the first embodiment, in order to further suppress reflection and white blur while ensuring image clarity, the haze of the first optical film is 18% or more and 38% or less, and the haze of the second optical film is is preferably 0.3% or more and 29% or less, the first optical film has a haze of 20% or more and 35% or less, and the second optical film has a haze of 0.5% or more and 28% or less. More preferably, the haze of the first optical film is 23% or more and 35% or less, and the haze of the second optical film is 0.5% or more and 28% or less, and the haze of the first optical film is It is even more preferable that the haze of the second optical film is 25% or more and 35% or less, and the haze of the second optical film is 0.5% or more and 28% or less, and the haze of the first optical film is 27% or more and 34% or less, and It is particularly preferable that the haze of the second optical film is 0.8% or more and 27% or less.

Hereinafter, the optical film set according to the first embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of an optical film set according to the first embodiment. The optical film set 100 shown in FIG. 1 has a first optical film 10 and a second optical film 20 . The first optical film 10 is an optical film arranged on the viewing side of the image display cell 201 (see FIG. 5) via a cover window 202 (see FIG. 5). The second optical film 20 is an optical film arranged on the image display cell 201 (see FIG. 5) side of the cover window 202 (see FIG. 5) via an air layer 204 (see FIG. 5).

The first optical film 10 has a first transparent film substrate 11, a first hard coat layer 12 and a first antireflection layer 13 in this order. The second optical film 20 has a second transparent film substrate 21, a second hard coat layer 22 and a second antireflection layer 23 in this order. The haze of the first optical film 10 is preferably 15% or more and 40% or less. The haze of the second optical film 20 is preferably 30% or less.

The first optical film included in the optical film set according to the first embodiment has only a first transparent film substrate 11, a first hard coat layer 12 and a first antireflection layer 13, as shown in FIG. good too. Also, the first optical film included in the optical film set according to the first embodiment may have a layer configuration different from that of the first optical film 10 shown in FIG. For example, the first optical film included in the optical film set according to the first embodiment is, as shown in FIG. The first optical film 30 may further have a first adhesive layer 31 disposed thereon. The first optical film 30 has a first adhesive layer 31, a first transparent film substrate 11, a first hard coat layer 12 and a first antireflection layer 13 in this order.

A release liner (not shown) may be temporarily attached to the main surface of the first pressure-sensitive adhesive layer 31 opposite to the first transparent film substrate 11 side. The release liner protects the surface of the first pressure-sensitive adhesive layer 31, for example, until the first optical film 30 is attached to a cover window 202 (see FIG. 5), which will be described later. Plastic films made of acrylic, polyolefin, cyclic polyolefin, polyester or the like are preferably used as the constituent material of the release liner. The thickness of the release liner is, for example, 5 μm or more and 200 μm or less. The surface of the release liner is preferably subjected to release treatment. Examples of release agent materials used in release treatment include silicone-based materials, fluorine-based materials, long-chain alkyl-based materials, fatty acid amide-based materials, and the like.

The second optical film included in the optical film set according to the first embodiment has only the second transparent film substrate 21, the second hard coat layer 22 and the second antireflection layer 23, as shown in FIG. good too. Also, the second optical film included in the optical film set according to the first embodiment may have a layer configuration different from that of the second optical film 20 shown in FIG. For example, the second optical film included in the optical film set according to the first embodiment, as shown in FIG. It may be the second optical film 40 further having a polarizer 41 disposed thereon. The second optical film 40 shown in FIG. 3 further has a transparent protective film 42 arranged on the main surface 41a of the polarizer 41 opposite to the second transparent film substrate 21 side. That is, the second optical film 40 has the transparent protective film 42, the polarizer 41, the second transparent film substrate 21, the second hard coat layer 22 and the second antireflection layer 23 in this order.

The transparent protective film 42 is not particularly limited as long as it is a transparent film that can protect the polarizer 41. For example, a transparent film made of a cellulose-based resin such as triacetyl cellulose, a transparent film made of a polyvinyl alcohol-based resin, or the like can be used. A film, a transparent film made of an acrylic resin, or the like can be used. The thickness of the transparent protective film 42 is, for example, 10 μm or more and 100 μm or less. Note that the transparent protective film 42 may be omitted in the first embodiment. In other words, the second optical film is an optical film that has the polarizer 41, the second transparent film substrate 21, the second hard coat layer 22, and the second antireflection layer 23 in this order and does not have the transparent protective film 42. There may be.

Further, in the first embodiment, even if the polarizer 41 is arranged on the main surface 21a of the second transparent film substrate 21 opposite to the second hard coat layer 22 side via a transparent protective film (not shown). good. In this case, the second transparent film substrate 21 and the transparent protective film can be bonded together with, for example, a transparent pressure-sensitive adhesive or a transparent adhesive. Examples of the transparent protective film disposed between the polarizer 41 and the second transparent film substrate 21 include a transparent film made of cellulose-based resin such as triacetyl cellulose, and a transparent film made of polyvinyl alcohol-based resin. A film, a transparent film made of an acrylic resin, or the like can be used. Moreover, the thickness of the transparent protective film arranged between the polarizer 41 and the second transparent film substrate 21 is, for example, 10 μm or more and 100 μm or less. Note that the transparent protective film disposed between the polarizer 41 and the second transparent film substrate 21 and the transparent protective film 42 are made of different materials, even if they are made of the same material. It may be a film. Moreover, the thickness of the transparent protective film arranged between the polarizer 41 and the second transparent film substrate 21 and the thickness of the transparent protective film 42 may be the same or different.

Moreover, as shown in FIG. 4, the second optical film included in the optical film set according to the first embodiment is a second pressure-sensitive adhesive disposed on the opposite side of the polarizer 41 from the second transparent film substrate 21 side. It may be a second optical film 50 further comprising a layer 51 . In the second optical film 50 shown in FIG. 4, the second pressure-sensitive adhesive layer 51 is arranged on the main surface 42a of the transparent protective film 42 opposite to the polarizer 41 side. That is, the second optical film 50 has the second adhesive layer 51, the transparent protective film 42, the polarizer 41, the second transparent film substrate 21, the second hard coat layer 22 and the second antireflection layer 23 in this order. .

A release liner (not shown) may be temporarily attached to the main surface of the second pressure-sensitive adhesive layer 51 opposite to the transparent protective film 42 side. The release liner protects the surface of the second pressure-sensitive adhesive layer 51, for example, until the second optical film 50 is attached to an image display cell 201 (see FIG. 5), which will be described later. Plastic films made of acrylic, polyolefin, cyclic polyolefin, polyester or the like are preferably used as the constituent material of the release liner. The thickness of the release liner is, for example, 5 μm or more and 200 μm or less. The surface of the release liner is preferably subjected to release treatment. Examples of release agent materials used in release treatment include silicone-based materials, fluorine-based materials, long-chain alkyl-based materials, fatty acid amide-based materials, and the like.

The configuration of the optical film set according to the first embodiment has been described above with reference to the drawings. Next, the elements of the optical film set according to the first embodiment (more specifically, the elements of the first optical film and the elements of the second optical film) will be described.

[First optical film]
{First transparent film substrate 11}
As a material constituting the first transparent film substrate 11, a resin material having excellent transparency, mechanical strength, and thermal stability is preferable. Specific examples of resin materials include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) Examples include acrylic resins, cyclic polyolefin resins (more specifically, norbornene resins, etc.), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The visible light transmittance of the first transparent film substrate 11 is preferably 80% or higher, more preferably 90% or higher.

The thickness of the first transparent film substrate 11 is not particularly limited, but is preferably 5 μm or more and 300 μm or less, and preferably 10 μm or more and 250 μm or less, from the viewpoint of strength, workability such as handleability, thin layer property, and the like. is more preferable, and more preferably 20 μm or more and 200 μm or less.

{First hard coat layer 12}
The first hard coat layer 12 is a layer that enhances mechanical properties such as hardness and elastic modulus of the first optical film. In order to easily adjust the haze of the first optical film to the range of 15% or more and 40% or less, the first hard coat layer 12 must contain a binder and particles having an average particle diameter of 1.0 μm or more and 8.0 μm or less (hereinafter referred to as , sometimes referred to as “microparticles”). The first hard coat layer 12 containing microparticles exhibits an antiglare property because the surface thereof is uneven. As used herein, the term “binder” refers to a cured product of resin or a cured product of a composite material of nanoparticles and resin, which will be described later. Moreover, the binder before hardening may be described as a "binder raw material."

The haze of the first optical film is determined by, for example, the average particle size of the microparticles, the amount of the microparticles in the first hard coat layer 12, and the difference (refractive index difference) between the refractive index of the microparticles and the refractive index of the binder. It can be adjusted by changing at least one of them. In order to easily adjust the haze of the first optical film to the range of 15% or more and 40% or less, the haze of the first hard coat layer 12 is preferably 15% or more and 40% or less.

(binder raw material)
As a binder material that can be used to form the first hard coat layer 12, curable resins such as thermosetting resins, photo-curable resins, and electron beam curable resins are preferably used. Types of curable resins include polyester resins, acrylic resins, urethane resins, acrylic urethane resins, amide resins, silicone resins, silicate resins, epoxy resins, melamine resins, oxetane resins, and acrylic resins. Urethane-based resins and the like are included. One or more curable resins can be used. Among these, one or more selected from the group consisting of acrylic resins, acrylic urethane resins, and epoxy resins are preferable because they have high hardness and can be photocured, and acrylic resins and acrylic urethane resins. More preferably, one or more selected from the group consisting of As will be described later, the binder raw material may contain an inorganic component such as inorganic nanoparticles in addition to the resin component (organic component). The refractive index of the binder, which is a cured product of the binder raw material, is, for example, 1.4 or more and 1.6 or less.

The photocurable resin contains a polyfunctional compound having two or more photopolymerizable (preferably ultraviolet polymerizable) functional groups in one molecule. Polyfunctional compounds may be monomeric or oligomeric. As the photopolymerizable polyfunctional compound, a compound containing two or more (meth)acryloyl groups in one molecule is preferably used.

Specific examples of polyfunctional compounds having two or more (meth)acryloyl groups in one molecule include tricyclodecanedimethanol diacrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol. tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane triacrylate, dimethylolpropane tetraacrylate, 1,6-hexanediol di(meth)acrylate, 1 ,9-nonanediol diacrylate, 1,10-decanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, dipropylene glycol diacrylate, isocyanuric acid tri(meth)acrylate, ethoxylated glycerin triacrylate, ethoxylated pentaerythritol tetraacrylate, and oligomers or prepolymers thereof;

Acrylic urethane-based resins contain urethane (meth)acrylate monomers, oligomers, or prepolymers as polyfunctional compounds. The number of (meth)acryloyl groups in one molecule of the urethane (meth)acrylate is preferably 3 or more, more preferably 4 or more and 15 or less, and even more preferably 6 or more and 12 or less. The molecular weight of the urethane (meth)acrylate oligomer is, for example, 3000 or less, preferably 500 or more and 2500 or less, more preferably 800 or more and 2000 or less. Urethane (meth)acrylate is obtained, for example, by reacting hydroxy (meth)acrylate obtained from (meth)acrylic acid or (meth)acrylic acid ester and polyol with diisocyanate.

The amount of the polyfunctional compound is preferably 50 parts by weight or more, preferably 60 parts by weight or more, with respect to a total of 100 parts by weight of the resin components (monomers, oligomers, and prepolymers that form the binder by curing) of the binder raw material. It is more preferable that the amount is 70 parts by weight or more. If the amount of the polyfunctional compound is within the above range, the hardness of the first hard coat layer 12 tends to be increased.

The binder raw material may further contain a monofunctional monomer. The amount of the monofunctional monomer is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 30 parts by weight or less with respect to 100 parts by weight of the resin component of the binder raw material. .

(microparticle)
Microparticles that can be used to form the first hard coat layer 12 include metal (or metalloid) oxide particles such as silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide; Glass particles; crosslinked or uncrosslinked resin particles made of various transparent polymers such as polymethyl methacrylate, styrene resin, polyurethane, styrene-acrylic copolymer, benzoguanamine resin, melamine resin, polycarbonate, silicone resin, etc. without particular limitation Available. These particles can be used singly or in combination of two or more.

In order to further suppress reflection and white blur while ensuring image clarity, the difference (refractive index difference) between the refractive index of the microparticles and the binder is 0.01 or more and 0.10 or less. Preferably. When multiple types of microparticles are used, the refractive index of the microparticles for calculating the refractive index difference is the average refractive index of the multiple types of microparticles used. For example, when using particles A (refractive index: na, weight ratio: x) and particles B (refractive index: nb, weight ratio: y), the average refractive index is calculated by the formula average refractive index = na × x + nb × y (where 0<x<1, 0<y<1, and x+y=1).

In order to further suppress reflection and white blur while ensuring image clarity, the average particle diameter of the microparticles is preferably 2.0 μm or more and 5.0 μm or less, and more preferably 2.5 μm or more and 4.0 μm. The following are more preferable.

Although the shape of the microparticles is not particularly limited, spherical particles having an aspect ratio of 1.5 or less are preferable from the viewpoint of reducing glare. The aspect ratio of the spherical particles is preferably 1.3 or less, more preferably 1.1 or less.

In order to further suppress reflection and white blur while ensuring image clarity, the amount of microparticles (when using multiple types of microparticles, the total amount of these multiple types of microparticles) With respect to 100 parts by weight, it is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, further preferably 1.0 parts by weight or more, and 1.5 parts by weight or more, or 2.0 parts by weight or more. In order to further suppress reflection and white blur while ensuring image clarity, the amount of microparticles (when using multiple types of microparticles, the total amount of these multiple types of microparticles) With respect to 100 parts by weight, it is preferably 20.0 parts by weight or less, more preferably 15.0 parts by weight or less, and may be 14.0 parts by weight or less.

(Nanoparticles)
The first hard coat layer 12 may contain particles having a number average primary particle diameter of less than 1.0 μm (hereinafter sometimes referred to as “nanoparticles”) as a binder component. For example, the first hard coat layer 12 contains nanoparticles having a number average primary particle diameter of 10 nm or more and 100 nm or less, so that the surface of the first hard coat layer 12 has a smaller size than the unevenness formed by the microparticles. are formed, and the adhesion between the first hard coat layer 12 and the first antireflection layer 13 formed thereon tends to improve. In addition, by including nanoparticles having a number average primary particle diameter sufficiently smaller than the wavelength of visible light (e.g., 100 nm or less), the transparency of the first hard coat layer 12 can be reduced without reducing the refractive index of the binder. You can adjust the rate.

From the viewpoint of enhancing dispersibility in the binder, the number average primary particle size of the nanoparticles is preferably 15 nm or more, more preferably 20 nm or more. From the viewpoint of forming a fine uneven shape that contributes to the improvement of adhesion, the number average primary particle diameter of the nanoparticles is preferably 90 nm or less, more preferably 70 nm or less, and further preferably 50 nm or less. preferable.

Inorganic oxides are preferred as the material for the nanoparticles. Examples of inorganic oxides include metal (or metalloid) oxides such as silicon oxide (silica), titanium oxide, aluminum oxide, zirconium oxide, niobium oxide, zinc oxide, tin oxide, cerium oxide, and magnesium oxide. The inorganic oxide may be a composite oxide of multiple (semi)metals. Among the exemplified inorganic oxides, silicon oxide is preferable because it has a high effect of improving adhesion. That is, the nanoparticles are preferably particles of silicon oxide (nanosilica particles). A functional group such as an acrylic group or an epoxy group may be introduced into the surface of the inorganic oxide particles as nanoparticles for the purpose of enhancing adhesion and affinity with the resin.

The amount of nanoparticles in the first hard coat layer 12 is preferably 5 parts by weight or more, 10 parts by weight or more, and 20 parts by weight with respect to 100 parts by weight of the total amount of the binder component (total amount of resin and nanoparticles). parts or more, or 30 parts by weight or more. When the amount of nanoparticles is 5 parts by weight or more, the refractive index of the binder can be easily adjusted while improving the adhesion to the layer formed on the first hard coat layer 12 . The upper limit of the amount of nanoparticles in the first hard coat layer 12 is, for example, 90 parts by weight, preferably 80 parts by weight, with respect to 100 parts by weight of the total amount of the binder component (total amount of resin and nanoparticles). , 70 parts by weight.

(Method for Forming First Hard Coat Layer 12)
The first hard coat layer 12 is formed by applying the hard coat composition onto the first transparent film substrate 11 and optionally removing the solvent and curing the resin. The hard coat composition contains, for example, the above-described binder raw material (resin or composite material of resin and nanoparticles) and microparticles, and optionally contains a solvent capable of dissolving or dispersing these components. When the resin component in the hard coat composition is a curable resin, the hard coat composition preferably contains an appropriate polymerization initiator. For example, when the resin component in the hard coat composition is a photocurable resin, the hard coat composition preferably contains a photopolymerization initiator.

In addition to the above components, the hard coat composition contains a leveling agent, a viscosity modifier (thixotropic agent, thickener, etc.), an antistatic agent, an antiblocking agent, a dispersant, a dispersion stabilizer, an antioxidant, and an ultraviolet absorber. , antifoaming agents, surfactants, and lubricants.

When the hard coat composition contains a thixotropic agent, sedimentation of the microparticles is suppressed, unevenness due to the microparticles is uniformly formed on the surface of the first hard coat layer 12, and a surface shape suitable for reducing glare is easily formed. tend to become Thixotropic agents include organic clays, polyolefin oxides, modified urea, and the like. Among them, organic clay such as smectite is preferable. The amount of the thixotropic agent compounded is preferably 0.3 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the binder raw material.

When the hard coat composition contains a leveling agent, the surface shape of the first hard coat layer 12 tends to be made uniform. Examples of leveling agents include fluorine-based leveling agents and silicone-based leveling agents. The blending amount of the leveling agent is preferably 0.01 parts by weight or more and 3 parts by weight or less with respect to 100 parts by weight of the raw material for the binder.

As a method for applying the hard coat composition, any suitable method such as bar coating, roll coating, gravure coating, rod coating, slot orifice coating, curtain coating, fountain coating, comma coating, etc. can be used. can be adopted. The heating temperature after application may be set to an appropriate temperature depending on the composition of the hard coat composition, and is, for example, 50° C. or higher and 150° C. or lower. When the resin component in the hard coat composition is a photocurable resin, photocuring is performed by irradiating active energy rays such as ultraviolet rays. The integrated light quantity of the irradiation light is preferably 100 mJ/cm ² or more and 500 mJ/cm ² or less.

Before forming the first antireflection layer 13, the first hard coat layer 12 is subjected to surface treatment for the purpose of further improving adhesion between the first hard coat layer 12 and the first antireflection layer 13, for example. may be broken. Examples of surface treatment include surface modification treatments such as corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, alkali treatment, acid treatment, and treatment with a coupling agent. A vacuum plasma treatment may be performed as the surface treatment. The surface roughness of the first hard coat layer 12 can also be adjusted by vacuum plasma treatment. The discharge power of the vacuum plasma treatment (for example, argon plasma treatment) is, for example, 0.5 kW or more and 10 kW or less, preferably 1 kW or more and 5 kW or less.

(Characteristics of first hard coat layer 12)
The thickness of the first hard coat layer 12 is not particularly limited, but is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more in order to achieve high hardness. On the other hand, in order to suppress a decrease in strength due to cohesive failure, the thickness of the first hard coat layer 12 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 12 μm or less. . The thickness of the first hard coat layer 12 is preferably in the range of 1.2 to 4 times the average particle diameter of the microparticles, more preferably in the range of 1.5 to 3 times. preferable. When the ratio of the average particle size of the microparticles to the thickness of the first hard coat layer 12 is within the above range, the uneven shape formed on the surface of the first hard coat layer 12 has excellent antiglare properties and less glare. It is likely to be suitable for display.

The arithmetic mean roughness Ra of the surface of the first hard coat layer 12 is preferably 0.05 μm or more and 0.25 μm or less, more preferably 0.06 μm or more and 0.20 μm or less, and 0.07 μm or more and 0.07 μm or more. It is more preferably 0.18 μm or less. The average spacing RSm of the unevenness on the surface of the first hard coat layer 12 is preferably 60 μm or more and 200 μm or less, more preferably 80 μm or more and 180 μm or less, and even more preferably 100 μm or more and 160 μm or less. The surface shape parameter of the first hard coat layer 12 is obtained from a roughness curve obtained by passing a cross-sectional curve with a reference length of 4 mm measured by a stylus surface roughness tester through a wide-area filter with a cutoff value of 0.8 mm, and then JIS Calculated according to B0601:2001.

By changing the average particle size and content of the microparticles, the arithmetic mean roughness Ra and the average spacing RSm can be adjusted. As the content of microparticles increases, the number of protrusions formed by the microparticles increases, so the average interval RSm tends to decrease. Further, the arithmetic mean roughness Ra tends to increase as the average particle size of the microparticles increases and the content of the microparticles increases.

The root-mean-square roughness Rq of the surface of the first hard coat layer 12 is preferably 0.06 μm or more and 0.30 μm or less, more preferably 0.08 μm or more and 0.25 μm or less, and 0.09 μm or more. It is more preferably 0.20 μm or less. The maximum cross-sectional height Rt of the surface of the first hard coat layer 12 is preferably 0.3 μm or more and 2.5 μm or less, more preferably 0.5 μm or more and 2.0 μm or less, and 0.7 μm or more and 1 It is more preferably 0.7 μm or less. The maximum height Rz of the surface of the first hard coat layer 12 is preferably 0.1 μm or more and 1.5 μm or less, more preferably 0.3 μm or more and 1.0 μm or less, and more preferably 0.4 μm or more and 0.4 μm or more. It is more preferably 9 μm or less. The ten-point average height Rz _JIS of the surface of the first hard coat layer 12 is preferably 0.05 μm or more and 1.0 μm or less, more preferably 0.1 μm or more and 0.8 μm or less, and 0.2 μm. More preferably, the thickness is not less than 0.6 μm and not more than 0.6 μm.

The average inclination angle θa of the surface of the first hard coat layer 12 is preferably 0.1° or more and 1.1° or less, more preferably 0.15° or more and 1.0° or less. It is more preferably 2° or more and 0.8° or less, and particularly preferably 0.3° or more and 0.6° or less. The average inclination angle θa is the sum (h ₁ +h ₂ +h ₃ . ·+h _n ) divided by the reference length L, and using the value Δa, it is calculated from the following formula.
θa=tan ⁻¹ Δa

{First antireflection layer 13}
The first antireflection layer 13 is composed of two or more layers of thin films having different refractive indices. In general, the antireflection layer has an optical thickness (product of refractive index and thickness) of the thin film so that the reversed phases of incident light and reflected light cancel each other out. By making the antireflection layer a multi-layer laminate of two or more thin films having different refractive indices, the reflectance can be reduced in a wide wavelength range of visible light.

Materials for the thin film forming the first antireflection layer 13 include oxides, nitrides, and fluorides of metals (or metalloids). The first antireflection layer 13 is preferably an alternate laminate of high refractive index layers and low refractive index layers.

The high refractive index layer has, for example, a refractive index of 1.9 or more, preferably 2.0 or more. Materials for the high refractive index layer include titanium oxide, niobium oxide, zirconium oxide, tantalum oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and antimony-doped tin oxide (ATO). Among them, one or more selected from the group consisting of titanium oxide and niobium oxide is preferable. The low refractive index layer has, for example, a refractive index of 1.6 or less, preferably 1.5 or less. Materials for the low refractive index layer include silicon oxide, titanium nitride, magnesium fluoride, barium fluoride, calcium fluoride, hafnium fluoride, and lanthanum fluoride. Among them, silicon oxide is preferred. In particular, it is preferable to alternately stack a niobium oxide (Nb ₂ O ₅ ) thin film as a high refractive index layer and a silicon oxide (SiO ₂ ) thin film as a low refractive index layer. In addition to the low refractive index layer and the high refractive index layer, a medium refractive index layer having a refractive index greater than 1.6 and less than 1.9 may be provided.

Each of the high refractive index layer and the low refractive index layer preferably has a thickness of 5 nm or more and 200 nm or less, more preferably 10 nm or more and 150 nm or less. The film thickness of each layer may be designed so that the reflectance of visible light is reduced according to the refractive index, lamination structure, and the like. For example, as a laminated structure of a high refractive index layer and a low refractive index layer, from the first hard coat layer 12 side, a high refractive index layer with an optical thickness of 20 nm or more and 55 nm or less and a low refractive index layer with an optical thickness of 35 nm or more and 55 nm or less A four-layer structure consisting of a layer, a high refractive index layer with an optical thickness of 80 nm or more and 250 nm or less, and a low refractive index layer with an optical thickness of 100 nm or more and 150 nm or less.

A method for forming the thin film forming the first antireflection layer 13 is not particularly limited, and either a wet coating method or a dry coating method may be used. A dry coating method such as vacuum deposition, CVD, or sputtering is preferable because a thin film having a uniform thickness can be formed. Among them, the sputtering method is preferable because it is excellent in the uniformity of film thickness and can easily form a dense and high-strength film.

In the sputtering method, a thin film is formed by a roll-to-roll method while conveying a long film (specifically, the first transparent film substrate 11 having the first hard coat layer 12 formed thereon) in one direction (longitudinal direction). Continuous film formation is possible. In the sputtering method, film formation is performed while introducing an inert gas such as argon and, if necessary, a reactive gas such as oxygen into a chamber. The deposition of the oxide layer by the sputtering method can be carried out by either a method using an oxide target or reactive sputtering using a metal (or semi-metal) target. Reactive sputtering using a metal (or semi-metal) target is preferred for depositing a metal oxide film at a high rate.

{First adhesive layer 31}
The adhesive constituting the first adhesive layer 31 is not particularly limited, and examples thereof include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate-vinyl chloride copolymers, modified polyolefins, epoxy A transparent pressure-sensitive adhesive whose base polymer is a polymer such as a base resin, a fluororesin, a natural rubber, or a synthetic rubber can be appropriately selected and used.

As a pressure-sensitive adhesive excellent in optical transparency and adhesiveness, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferably used. When using an acrylic pressure-sensitive adhesive as the pressure-sensitive adhesive that constitutes the first pressure-sensitive adhesive layer 31, the content of the acrylic polymer with respect to the total solid content of the pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer 31 is 50. It is preferably at least 70% by weight, even more preferably at least 80% by weight.

As the acrylic polymer, one having a main skeleton of a monomer unit derived from a (meth)acrylic acid alkyl ester is preferably used. As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferably used. The (meth)acrylic acid alkyl ester may have a branched alkyl group. Examples of (meth)acrylic acid alkyl esters having branched alkyl groups include 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, isotetradecyl (meth)acrylate, Isooctadecyl (meth)acrylate and the like are preferably used.

The content of the (meth)acrylic acid alkyl ester in the monomer for forming the acrylic polymer is preferably 40% by weight or more, preferably 50% by weight, based on the total amount of the monomer component for forming the acrylic polymer. % or more, more preferably 60% by weight or more. The acrylic polymer may be a copolymer of multiple types of (meth)acrylic acid alkyl esters, and may be a copolymer of a straight-chain alkyl (meth)acrylate and a branched alkyl (meth)acrylate. There may be. The arrangement of constituent monomer units in the copolymer may be random or block.

An acrylic monomer having a crosslinkable functional group may be used as the monomer for forming the acrylic polymer. Acrylic monomers having a crosslinkable functional group include hydroxy group-containing monomers (more specifically, hydroxyethyl acrylate and the like), carboxy group-containing monomers, and the like.

A polyfunctional monomer may be used as the monomer for forming the acrylic polymer. The use of polyfunctional monomers tends to increase the storage modulus of the pressure-sensitive adhesive. A polyfunctional monomer is a monomer having at least two polymerizable functional groups having unsaturated double bonds such as (meth)acryloyl groups or vinyl groups.

The method for forming the first adhesive layer 31 is not particularly limited. For example, the adhesive composition is polymerized by a known polymerization method such as solution polymerization, photopolymerization, bulk polymerization, emulsion polymerization, and A layer 31 can be formed. When photopolymerization is employed as the polymerization method, for example, a pressure-sensitive adhesive composition containing a monomer, a solvent, a photopolymerization initiator, additives (silane coupling agents, tackifiers, etc.) added as necessary, After coating on the release liner, the pressure-sensitive adhesive composition is irradiated with light (for example, ultraviolet rays) to promote polymerization of the pressure-sensitive adhesive composition. Next, the first adhesive layer 31 can be formed on the main surface 11a of the first transparent film substrate 11 by laminating the layer composed of the adhesive composition after light irradiation to the first transparent film substrate 11. can.

Although the thickness of the first pressure-sensitive adhesive layer 31 is not particularly limited, it is preferably 5 μm or more and 100 μm or less from the viewpoint of achieving both thin layer properties and adhesiveness.

[Second optical film]
{Second transparent film substrate 21}
Examples of the material forming the second transparent film substrate 21 include the same materials as those exemplified as the materials forming the first transparent film substrate 11 described above. The second transparent film substrate 21 and the first transparent film substrate 11 may be made of the same kind of material, or may be made of different kinds of materials.

A preferable range of the thickness of the second transparent film substrate 21 is the same as the preferable range of the thickness of the first transparent film substrate 11 described above, for example. The thickness of the second transparent film substrate 21 and the thickness of the first transparent film substrate 11 may be the same or different.

{Second hard coat layer 22}
The second hard coat layer 22 is a layer that enhances mechanical properties such as hardness and elastic modulus of the second optical film. When the haze of the second optical film is adjusted to a relatively low range (for example, 0.8% or less), the second hard coat layer 22 may not contain microparticles. The second hard coat layer 22 may contain only at least one of the resin components listed as the binder raw material for the layer 12 . On the other hand, in order to easily adjust the haze of the second optical film to a range of 0.9% or more, the second hard coat layer 22, like the first hard coat layer 12, contains a binder and microparticles. preferably included.

The haze of the second optical film is determined, for example, by the amount of microparticles in the second hard coat layer 22, the average particle diameter of the microparticles, and the difference (refractive index difference) between the refractive index of the microparticles and the refractive index of the binder. It can be adjusted by changing at least one of them. In order to easily adjust the haze of the second optical film to a range of 30% or less, the haze of the second hard coat layer 22 is preferably 30% or less.

Examples of the constituent components of the second hard coat layer 22 include the same constituent components as those exemplified as the constituent components of the first hard coat layer 12 described above. The preferable content range of each component of the second hard coat layer 22 is the same as the preferable content range of each component of the first hard coat layer 12 described above, for example. The constituents of the second hard coat layer 22 and the constituents of the first hard coat layer 12 may be the same or different. Also, the content of each component of the second hard coat layer 22 and the content of each component of the first hard coat layer 12 may be the same or different.

As for the method for forming the second hard coat layer 22, the first hard coat layer 12 described above is used except that the hard coat composition is applied onto the second transparent film substrate 21 instead of the first transparent film substrate 11. The same method as the formation method of can be adopted.

The range of preferable properties (thickness, surface shape parameters, etc.) of the second hard coat layer 22 is also the same as the range of preferable properties of the first hard coat layer 12 described above. The properties of the second hard coat layer 22 and the properties of the first hard coat layer 12 may be the same or different.

{Second antireflection layer 23}
The configuration of the second antireflection layer 23 may be, for example, the same configuration as the configuration of the first antireflection layer 13 described above. Further, examples of materials for the thin film forming the second antireflection layer 23 include the same materials as those exemplified as the materials for the thin film forming the first antireflection layer 13 described above. The configuration of the second antireflection layer 23 and the configuration of the first antireflection layer 13 may be the same or different. The material of the thin film forming the second antireflection layer 23 and the material of the thin film forming the first antireflection layer 13 may be the same or different.

Regarding the method of forming the second antireflection layer 23, instead of the first transparent film substrate 11 having the first hard coat layer 12 formed thereon, the second transparent film substrate 21 having the second hard coat layer 22 formed thereon. The same method as the method for forming the first antireflection layer 13 described above can be employed, except that the film is formed using .

A preferable range of the thickness of the second antireflection layer 23 is the same as the preferable range of the thickness of the first antireflection layer 13 described above, for example. The thickness of the second antireflection layer 23 and the thickness of the first antireflection layer 13 may be the same or different.

{polarizer 41}
As the polarizer 41, for example, a polyvinyl alcohol film containing a dichroic material such as iodine or a dichroic dye can be used. Polyvinyl alcohol or a derivative thereof is used as the material of the polyvinyl alcohol film applied to the polarizer 41 . Derivatives of polyvinyl alcohol include, for example, polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene; carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and their alkyl esters; Polyvinyl alcohol is mentioned. As polyvinyl alcohol, for example, one having a degree of polymerization of 1000 or more and 10000 or less and a degree of saponification of 80 mol % or more and 100 mol % or less can be used.

The polarizer 41 is obtained by dyeing and stretching the polyvinyl alcohol-based film with a dichroic material. The thickness of the polarizer 41 is, for example, 5 μm or more and 50 μm or less.

{Second adhesive layer 51}
As the adhesive that forms the second adhesive layer 51, for example, the same adhesive as that exemplified as the adhesive that forms the first adhesive layer 31 described above can be used. The pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer 51 and the pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer 31 may be of the same type or of different types.

As for the method for forming the second adhesive layer 51, the above-described method for forming the first adhesive layer 31 is used, except that the adhesive layer is formed on the side of the polarizer 41 opposite to the second transparent film substrate 21 side. can use the same method.

A preferable range of the thickness of the second adhesive layer 51 is, for example, the same as the preferable range of the thickness of the first adhesive layer 31 described above. The thickness of the second adhesive layer 51 and the thickness of the first adhesive layer 31 may be the same or different.

Although the optical film set (more specifically, the first optical film and the second optical film) according to the first embodiment has been described above, the optical film set according to the present invention is not limited to the above embodiments. For example, the first optical film and the second optical film included in the optical film set according to the present invention are a primer layer (more specifically, an inorganic film such as silicon oxide) disposed between the hard coat layer and the antireflection layer. layer made of oxide, etc.). Further, the first optical film and the second optical film included in the optical film set according to the present invention are antifouling layers (more specifically, fluorine a layer made of a contained compound, etc.).

<Second Embodiment: Image Display Device>
Next, an image display device according to a second embodiment of the invention will be described. The image display device according to the second embodiment includes an image display cell, a cover window arranged on the viewing side of the image display cell, and the optical film set according to the first embodiment. FIG. 5 is a cross-sectional view showing an example of an image display device according to the second embodiment. The image display device 200 shown in FIG. 5 includes an image display cell 201 , a cover window 202 arranged on the viewing side (upper side in FIG. 5 ) of the image display cell 201 , and an optical film set 150 . The optical film set 150 has the first optical film 30 and the second optical film 50 described above. The first optical film 30 is arranged on the viewing side of the cover window 202 with the first antireflection layer 13 facing the viewing side and the first adhesive layer 31 attached to the cover window 202 . The second optical film 50 is applied to the image display cell 201 side of the cover window 202 with the second antireflection layer 23 facing the viewer side and the second pressure-sensitive adhesive layer 51 attached to the image display cell 201 . It is arranged through layer 204 . That is, the air layer 204 exists between the main surface 202a of the cover window 202 on the image display cell 201 side and the main surface 23a of the second antireflection layer 23 on the viewing side.

Examples of the image display cell 201 include a liquid crystal cell and an organic EL cell. A transparent resin plate, a glass plate, or the like can be exemplified as a constituent material of the cover window 202 . The cover window 202 may be a transparent member with a touch panel. The thickness of the cover window 202 is, for example, 0.5 mm or more and 5.0 mm or less.

A decorative portion 203 is provided on the periphery of the air layer 204 . The decorative portion 203 is, for example, a printed layer printed in a frame shape on the main surface 202a of the cover window 202 on the image display cell 201 side. In this case, the decorative portion 203 (printed layer) and the second antireflection layer 23 can be attached together with an adhesive or pressure-sensitive adhesive.

The thickness of the air layer 204 can be adjusted by changing the thickness of the decorative portion 203 . In order to further suppress reflection and white blur while ensuring image clarity, the thickness of the air layer 204 is preferably 0.1 mm or more and 2.0 mm or less, and 0.1 mm or more and 1.5 mm or less. is more preferable. Also, the width of the decorative portion 203 is, for example, 1 mm or more and 10 mm or less.

In the image display device 200, by arranging the decorative portion 203, the lead wiring and the like are not visible from the outside, thereby improving the design. Note that the decorative portion 203 may be provided not only for the purpose of shielding light, but also for specifying the position of a switch or the like.

The decorative portion 203 may be provided by printing or the like on the main surface 23a of the second antireflection layer 23 on the viewing side. In this case, the decorative portion 203 and the cover window 202 can be attached together with an adhesive or adhesive.

Since the image display device according to the second embodiment includes the optical film set according to the first embodiment, it is possible to suppress reflection and white blur while ensuring image clarity.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

<Preparation of hard coat composition>
First, a method for preparing a hard coat composition used in producing an optical film, which will be described later, will be described.

[Preparation of hard coat composition H1]
A solution obtained by adding a composite of nanosilica particles and a curable acrylic resin to a toluene/cyclopentanone mixed solvent (weight ratio: 70/30) (number average primary particle diameter of nanosilica particles: 40 nm, nanosilica in solid content Particle ratio: 60% by weight, solid concentration: 50% by weight) and 33 parts by weight of polyfunctional acrylate were mixed. The obtained mixture and 100 parts by weight of the solid content of this mixture, crosslinked polymethyl methacrylate (PMMA) particles as microparticles ("Techpolymer (registered trademark) SSX-103" manufactured by Sekisui Plastics Co., Ltd., average Particle diameter: 3.0 μm, refractive index: 1.50) 2.0 parts by weight, organic smectite ("Smecton (registered trademark) SAN" manufactured by Kunimine Industries Co., Ltd.) 1.5 parts by weight as a thixotropic agent, and light 3.0 parts by weight of a polymerization initiator (“Omnirad (registered trademark) 907” manufactured by IGM Resins) and 0.38 weight of a silicone-based leveling agent (“Polyflow LE303” manufactured by Kyoeisha Chemical Co., Ltd., active ingredient concentration: 40% by weight) and diluted with a toluene/cyclopentanone mixed solvent (weight ratio: 70/30) to prepare a hard coat composition H1 having a solid concentration of 45% by weight. The refractive index of the binder (cured hybrid material of curable acrylic resin and nanosilica particles without PMMA particles) was 1.48. The amount of microparticles was 2.0 parts by weight with respect to 100 parts by weight of the binder. The amount of organic smectite (1.5 parts by weight) is the solid content (non-volatile content). Diluted. In the preparation of the following hard coat compositions H2 to H5, the amount of the organic smectite compounded was the solid content (non-volatile content), and the dilution ratio when compounding the organic smectite was the same as above (6 % by weight).

[Preparation of hard coat composition H2]
Urethane acrylate prepolymer (“UA-53H-80BK” manufactured by Shin-Nakamura Chemical Industry Co., Ltd., solid content concentration: 80% by weight) 50 parts by weight and polyfunctional acrylate (Osaka Organic Chemical Industry Co., Ltd.) containing pentaerythritol triacrylate as the main component ("Viscoat #300") was mixed with 60 parts by weight. The obtained mixture and particles of a copolymer resin of styrene and methyl methacrylate as microparticles ("Techpolymer (registered trademark) SSX-103DXE manufactured by Sekisui Plastics Co., Ltd." are added to 100 parts by weight of the solid content of this mixture. ”, Average particle diameter: 3.0 μm, refractive index: 1.53) 7.0 parts by weight, and silicone resin particles as microparticles (Momentive Performance Materials Japan Co., Ltd. “Tospearl (registered trademark) 130” , average particle diameter: 3.0 μm, refractive index: 1.43) 3.0 parts by weight, and 2.5 parts by weight of organized smectite ("Smecton (registered trademark) SAN" manufactured by Kunimine Industries Co., Ltd.) as a thixotropic agent , Photopolymerization initiator (IGM Resins "Omnirad (registered trademark) 907") 3.0 parts by weight, silicone leveling agent (DIC Corporation "Grandic (registered trademark) PC4100", active ingredient concentration: 10 weight %) and diluted with a toluene/cyclopentanone mixed solvent (weight ratio: 80/20) to prepare a hard coat composition H2 having a solid concentration of 40% by weight. The refractive index of the binder was 1.51. The amount of microparticles was 10.0 parts by weight with respect to 100 parts by weight of the binder.

[Preparation of hard coat composition H3]
50 parts by weight of a polyfunctional acrylate (“Viscoat #300” manufactured by Osaka Organic Chemical Industry Co., Ltd.) mainly composed of pentaerythritol triacrylate, and a urethane acrylate prepolymer (“UA-53H-80BK” manufactured by Shin-Nakamura Chemical Industry Co., Ltd., solid concentration: 80% by weight) were mixed with 63 parts by weight. The resulting mixture and 100 parts by weight of the solid content of this mixture, silicone resin particles as microparticles ("Tospearl (registered trademark) 130" manufactured by Momentive Performance Materials Japan, average particle size: 3 .0 μm, refractive index: 1.43) 3.5 parts by weight, organized smectite as a thixotropic agent (“Smecton (registered trademark) SAN” manufactured by Kunimine Industries Co., Ltd.) 2.0 parts by weight, and a photopolymerization initiator ( 3.0 parts by weight of "Omnirad (registered trademark) 907" manufactured by IGM Resins, and 2.0 parts by weight of a silicone-based leveling agent ("Grandic (registered trademark) PC4100" manufactured by DIC, active ingredient concentration: 10% by weight) and diluted with a toluene/cyclopentanone mixed solvent (weight ratio: 70/30) to prepare a hard coat composition H3 having a solid concentration of 33% by weight. The refractive index of the binder was 1.52. The amount of microparticles was 3.5 parts by weight with respect to 100 parts by weight of the binder.

[Preparation of hard coat composition H4]
A solution of an ultraviolet curable resin mainly composed of urethane acrylate as a binder raw material ("Unidic (registered trademark) 17-806" manufactured by DIC Corporation, solid content concentration: 80% by weight) and a solid content of the above resin solution. With respect to 100 parts by weight, 14.0 parts by weight of crosslinked styrene resin particles as microparticles (“SX-350H” manufactured by Soken Chemical Co., Ltd., average particle diameter: 3.5 μm, refractive index: 1.59) and thixotropy 2.5 parts by weight of organic smectite ("Smecton (registered trademark) SAN" manufactured by Kunimine Industries Co., Ltd.) as an agent and 5.0 parts by weight of a photopolymerization initiator ("Omnirad (registered trademark) 907" manufactured by IGM Resins) and 0.5 parts by weight of a leveling agent (“Megafac (registered trademark) F-556” manufactured by DIC), diluted with a mixed solvent of toluene/ethyl acetate (weight ratio: 90/10) to form a solid. A hard coat composition H4 having a concentration of 30% by weight was prepared. The refractive index of the binder was 1.51. The amount of microparticles was 14.0 parts by weight with respect to 100 parts by weight of the binder.

[Preparation of hard coat composition H5]
Crosslinked polymethyl methacrylate (PMMA) particles ("Techpolymer (registered trademark) SSX-103" manufactured by Sekisui Plastics Co., Ltd., average particle size: 3.0 μm, refractive index: 1.50) Except for not using , a hard coat composition H5 was prepared by the same preparation method as the hard coat composition H1.

<Preparation of adhesive sheet PS>
A pressure-sensitive adhesive sheet PS used in the production of an optical film, which will be described later, was produced by the following method. First, in a reaction vessel, 65 parts by weight of 2-ethylhexyl acrylate, 15 parts by weight of N-vinylpyrrolidone, 20 parts by weight of hydroxyethyl acrylate, and 1-hydroxycyclohexyl phenyl ketone ("Irgacure" manufactured by BASF) as a photopolymerization initiator. 0.1 part by weight of registered trademark) 184'') was added, and ultraviolet rays were irradiated in a nitrogen atmosphere to obtain a prepolymer composition having a polymerization rate of 10%. To 100 parts by weight of this prepolymer composition, 0.2 parts by weight of 2,2-dimethoxy-1,2-diphenylethan-1-one ("Irgacure (registered trademark) 651" manufactured by BASF) as a photopolymerization initiator , 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd. "NK Ester A-HD-N") 0.3 parts by weight as a multifunctional monomer, and 3-glycidoxypropyl as a silane coupling agent After adding 0.3 parts by weight of trimethoxysilane (“KBM-403” manufactured by Shin-Etsu Chemical Co., Ltd.), these were mixed to prepare an adhesive composition X.

Next, as release liners, two polyester films having one surface treated with silicone for release were prepared. On the release-treated surface of one of the release liner, the pressure-sensitive adhesive composition X was applied to form a coating layer so that the thickness after irradiation with ultraviolet rays, which will be described later, was 20 μm. Next, the release-treated surface of the other release liner was laminated onto the coating layer to obtain a laminate. Next, with a black light whose position is adjusted so that the irradiation intensity on the irradiation surface directly under the lamp is 5 mW/cm ² , the laminate is irradiated with ultraviolet light under the condition of an integrated light amount of 3000 mJ/cm ² to allow polymerization to proceed. , a pressure-sensitive adhesive sheet PS having release liners temporarily adhered to both sides was obtained.

<Preparation of polarizing plate PL>
As a polarizing plate used in the production of an optical film described later, a polarizer made of a stretched polyvinyl alcohol film having a thickness of 25 μm impregnated with iodine was provided with a transparent protective film made of triacetylcellulose having a thickness of 40 μm on one main surface, and a transparent protective film made of triacetylcellulose on the other main surface. A polarizing plate PL having a 30 μm-thick acrylic resin transparent protective film on its main surface was prepared.

<Production of optical film>
A method for producing an optical film used in Examples and Comparative Examples will be described below. In the following, the optical film arranged on the viewing side of the image display cell via the cover window is referred to as the first optical film, and the optical film arranged on the image display cell side of the cover window via an air layer is referred to as the second optical film. Optical film.

[Preparation of first optical film A1]
(Formation of hard coat layer)
The hard coat composition H1 was applied to an 80 μm-thick triacetyl cellulose film (“KC8UA” manufactured by Konica Minolta) using a comma coater (registered trademark) and heated at 80° C. for 1 minute. After that, ultraviolet rays were irradiated from a high-pressure mercury lamp under the condition of an accumulated light amount of 300 mJ/cm ² to cure the coating layer and form a hard coat layer having a thickness of 8.0 μm.

(Formation of antireflection layer)
The triacetyl cellulose film on which the hard coat layer was formed was introduced into a roll-to-roll type sputtering deposition apparatus, and while the film was running, _five Nb ₂ O layers with a thickness of 10.1 nm were formed on the hard coat layer. A 27.5 nm thick SiO ₂ layer, a 105.0 nm thick Nb ₂ O ₅ layer and an 83.5 nm thick SiO ₂ layer were deposited in this order. A Si target was used for the deposition of the SiO ₂ layer, and a Nb target was used for the deposition of the Nb ₂ O ₅ layer. In the deposition of the SiO ₂ layer and the Nb ₂ O ₅ layer, the amount of introduced oxygen was adjusted by plasma emission monitoring (PEM) control so that the deposition mode maintained the transition region.

(Formation of adhesive layer)
A triacetyl cellulose film having a hard coat layer and an antireflection layer formed thereon was cut into a size of 5 cm×5 cm. Next, the release liner on one side of the pressure-sensitive adhesive sheet PS described above is peeled off, and the exposed pressure-sensitive adhesive layer is attached to the main surface of the triacetyl cellulose film on the side opposite to the hard coat layer side to form the pressure-sensitive adhesive layer/triacetyl film. A first optical film A1 having a layer structure of cellulose film (transparent film substrate)/hard coat layer/antireflection layer was obtained.

The first optical film A1 was stored with a release liner temporarily attached to the main surface of the pressure-sensitive adhesive layer opposite to the triacetyl cellulose film side until before being attached to a glass plate, which will be described later. The first optical films A2 to A5, which will be described later, were also stored with the release liner temporarily attached in the same manner as the first optical film A1.

[Production of first optical film A2]
The first optical film A2 was prepared in the same manner as the first optical film A1 except that the hard coat composition H2 was used instead of the hard coat composition H1 and the thickness of the hard coat layer was changed to 8.5 μm. Obtained.

[Preparation of first optical film A3]
The first optical film A3 was prepared in the same manner as the first optical film A1 except that the hard coat composition H3 was used instead of the hard coat composition H1 and the thickness of the hard coat layer was changed to 6.3 μm. Obtained.

[Production of first optical film A4]
The hard coat composition H4 was used instead of the hard coat composition H1, the heat treatment for forming the hard coat layer was changed to 110°C for 1 minute, and the thickness of the hard coat layer was set to 5.0 µm. A first optical film A4 was obtained in the same manner as the first optical film A1, except for the changes.

[Preparation of first optical film A5]
A first optical film A5 was obtained in the same manner as the first optical film A1, except that the hard coat composition H5 was used instead of the hard coat composition H1.

[Preparation of Second Optical Film B1]
(Formation of hard coat layer)
The hard coat composition H1 was applied to an 80 μm-thick triacetyl cellulose film (“KC8UA” manufactured by Konica Minolta) using a comma coater (registered trademark) and heated at 80° C. for 1 minute. After that, ultraviolet rays were irradiated from a high-pressure mercury lamp under the condition of an accumulated light amount of 300 mJ/cm ² to cure the coating layer and form a hard coat layer having a thickness of 8.0 μm.

(Formation of antireflection layer)
The triacetyl cellulose film on which the hard coat layer was formed was introduced into a roll-to-roll type sputtering deposition apparatus, and while the film was running, _five Nb ₂ O layers with a thickness of 10.1 nm were formed on the hard coat layer. A 27.5 nm thick SiO ₂ layer, a 105.0 nm thick Nb ₂ O ₅ layer and an 83.5 nm thick SiO ₂ layer were deposited in this order. A Si target was used for the deposition of the SiO ₂ layer, and a Nb target was used for the deposition of the Nb ₂ O ₅ layer. In the deposition of the SiO ₂ layer and the Nb ₂ O ₅ layer, the amount of introduced oxygen was adjusted by plasma emission monitoring (PEM) control so that the deposition mode maintained the transition region.

(Lamination of polarizing plates)
A triacetyl cellulose film having a hard coat layer and an antireflection layer formed thereon was cut into a size of 5 cm×5 cm. Next, one release liner of the pressure-sensitive adhesive sheet PS is peeled off, and the exposed pressure-sensitive adhesive layer is adhered to the main surface of the triacetyl cellulose film opposite to the hard coat layer side, and then the other release liner is applied. peeled off. Next, the exposed pressure-sensitive adhesive layer is laminated to the triacetylcellulose transparent protective film of the polarizing plate PL described above to form a transparent protective film/polarizer/transparent protective film/adhesive layer/triacetylcellulose film (transparent film base). A second optical film B1 having a layer structure of material)/hard coat layer/antireflection layer was obtained.

[Preparation of Second Optical Film B2]
The second optical film B2 was prepared in the same manner as the second optical film B1 except that the hard coat composition H2 was used instead of the hard coat composition H1 and the thickness of the hard coat layer was changed to 8.5 μm. Obtained.

[Preparation of Second Optical Film B3]
The second optical film B3 was prepared in the same manner as the second optical film B1 except that the hard coat composition H3 was used instead of the hard coat composition H1 and the thickness of the hard coat layer was changed to 6.3 μm. Obtained.

[Preparation of second optical film B4]
The hard coat composition H4 was used instead of the hard coat composition H1, the heat treatment for forming the hard coat layer was changed to 110°C for 1 minute, and the thickness of the hard coat layer was set to 5.0 µm. A second optical film B4 was obtained in the same manner as the second optical film B1, except for the changes.

[Preparation of second optical film B5]
The second optical film B5 was prepared in the same manner as the second optical film B1 except that the hard coat composition H5 was used instead of the hard coat composition H1 and the thickness of the hard coat layer was changed to 6.0 μm. Obtained.

<Measurement of haze>
[Measurement of Haze of First Optical Film]
After bonding the pressure-sensitive adhesive layer of the first optical film to be measured to a glass plate (material: non-alkali glass, thickness: 1.5 mm), a haze meter ("HM-150" manufactured by Murakami Color Research Laboratory) was measured. The haze of the first optical film was measured by the method described in JIS K7136-2000 by irradiating light from the glass plate side. The results are shown in Table 1 below.

[Measurement of haze of second optical film]
Using a haze meter (“HM-150” manufactured by Murakami Color Research Laboratory), light is irradiated from the polarizing plate PL side of the second optical film to be measured, and the second optical film is measured by the method described in JIS K7136-2000. Haze of the optical film was measured. The results are shown in Table 1 below. In addition, after bonding a glass plate (material: non-alkali glass, thickness: 1.5 mm) to the polarizing plate PL of the second optical film to be measured via the adhesive layer of the separately prepared adhesive sheet PS, the haze When haze was measured by the method described in JIS K7136-2000 using a meter ("HM-150" manufactured by Murakami Color Research Laboratory), the same results as in Table 1 were obtained by irradiating light from the glass plate side. Got.

<Production of image display device for evaluation>
A method of manufacturing an evaluation image display device used for evaluation of Examples and Comparative Examples will be described below.

[Example 1]
First, the pressure-sensitive adhesive layer of the first optical film A3 was attached to a glass plate (material: non-alkali glass, thickness: 1.5 mm) as a cover window to obtain a first optical film A3 with a cover window. Using the first optical film A3 with a cover window, the second optical film B2, and the 8th generation iPad (registered trademark) manufactured by Apple Inc., an image display device for evaluation was produced by the following method. bottom.

The second optical film B2 was placed on the screen of the iPad (registered trademark) so that the polarizing plate PL was in contact with the screen. Next, a frame-shaped decorative portion (width: 5 mm) previously prepared from a resin sheet having a thickness of 0.4 mm was placed on the periphery of the antireflection layer of the second optical film B2. Next, the first optical film A3 with a cover window was placed on the decorative part so that the cover window was in contact with the decorative part, and an evaluation image display device of Example 1 was obtained. In this evaluation image display device, the thickness (the thickness of the air layer) between the antireflection layer of the second optical film B2 and the cover window was 0.4 mm.

[Examples 2 to 6 and Comparative Examples 1 to 19]
Images for evaluation of Examples 2 to 6 and Comparative Examples 1 to 19 in the same manner as in Example 1, except that the combination of the first optical film and the second optical film was changed to the combination shown in Table 1 below. A display device was obtained respectively.

<Evaluation>
[Evaluation of reflection]
In a dark room, the screen of the image display device for evaluation was turned off, and a three-wavelength fluorescent lamp installed at a position 50 cm directly above the image display device for evaluation was turned on. Then, the degree of reflection of the fluorescent tube was visually determined according to the following criteria. The larger the judgment value, the better the evaluation, and when the judgment value was 3 or more, it was evaluated as "reflection is suppressed." On the other hand, when the judgment value was 2 or less, it was evaluated as "reflection is not suppressed".

(Reflection criteria)
5: Reflection was not confirmed at all.
4: Reflection was slightly confirmed.
3: Although reflection was confirmed, it was practically no problem.
2: Reflection was clearly confirmed.
1: Reflection was very clearly confirmed.

[Evaluation of Image Clarity]
In a dark room, the brightness of the screen of the image display device for evaluation was maximized to display black characters (size: 12 points) on a white background, and the screen was viewed from directly above at a distance of 30 cm from the image display device for evaluation. . Then, the degree of image sharpness was determined according to the following criteria. The larger the judgment value, the better the evaluation, and when the judgment value was 3 or more, it was evaluated as "image clarity can be secured". On the other hand, when the judgment value was 2 or less, it was evaluated as "image clarity cannot be ensured".

(Determination criteria for image clarity)
5: The image was clear.
4: A few unclear spots were observed in the image.
3: Unclear portions were observed in the image, but there was no practical problem.
2: The entire image was unclear.
1: The entire image was extremely unclear.

[Evaluation of white blur]
In a dark room, the screen of the image display device for evaluation was turned off, and a three-wavelength fluorescent lamp installed at a position 50 cm directly above the image display device for evaluation was turned on. Then, the degree of white blurring was determined visually according to the following criteria. The larger the judgment value, the better the evaluation, and when the judgment value was 3 or more, it was evaluated as "white blur is suppressed." On the other hand, when the judgment value was 2 or less, it was evaluated as "white blur is not suppressed".

(Determination criteria for white blur)
5: No white blur was observed at all.
4: White blurring was slightly observed.
3: Although white blurring was observed, it was practically no problem.
2: White blur was clearly confirmed.
1: White blur was very clearly confirmed.

<Evaluation results>
Table 1 shows the combinations of the first optical film and the second optical film and the evaluation values for Examples 1 to 6 and Comparative Examples 1 to 19. In Examples 1 to 6 and Comparative Examples 1 to 19, the thickness of the air layer was changed to 0.6 mm and 1.0 mm, respectively, and evaluated by the same method as described above. The same results as in Table 1 were obtained for any of 1 to 19.

In Examples 1 to 6, the haze of the first optical film was 15% or more and 40% or less. Further, in Examples 1 to 6, the haze of the second optical film was 30% or less. In Examples 1 to 6, image clarity was ensured, and glare and white blurring were also suppressed.

In Comparative Examples 10-19, the haze of the first optical film was less than 15%. In Comparative Examples 1 to 5, the haze of the first optical film exceeded 40%. In Comparative Examples 1, 2, 6 to 11, 16 and 17, the haze of the second optical film exceeded 30%. In Comparative Examples 1 to 10 and 16, image sharpness was not ensured. In Comparative Examples 10 to 19, reflection was not suppressed. In Comparative Examples 1 to 5, white blur was not suppressed.

The above results show that the optical film set according to the present invention can suppress reflection and white blur while ensuring image clarity in an image display device in which a cover window is provided via an air layer. rice field.

10, 30 First optical film 11 First transparent film substrate 12 First hard coat layer 13 First antireflection layer 20, 40, 50 Second optical film 21 Second transparent film substrate 22 Second hard coat layer 23 2 antireflection layer 31 first adhesive layer 41 polarizer 51 second adhesive layers 100, 150 optical film set 200 image display device 201 image display cell 202 cover window 204 air layer

Claims (7)

An optical film set comprising a first optical film disposed on the viewing side of an image display cell via a cover window, and a second optical film disposed on the image display cell side of the cover window via an air layer. There is
The first optical film has a first transparent film substrate, a first hard coat layer and a first antireflection layer in this order,
The second optical film has a second transparent film substrate, a second hard coat layer and a second antireflection layer in this order,
haze of the first optical film is 15% or more and 40% or less;
The optical film set, wherein the second optical film has a haze of 30% or less. 2. The optical film set according to claim 1, wherein the first optical film further has a first pressure-sensitive adhesive layer disposed on the side opposite to the first hard coat layer side of the first transparent film base. 3. The optical film set according to claim 1, wherein the second optical film further comprises a polarizer arranged on the side opposite to the second hard coat layer side of the second transparent film base. 4. The optical film set according to claim 3, wherein the second optical film further has a second pressure-sensitive adhesive layer disposed on the opposite side of the polarizer to the second transparent film substrate. The optical film set according to any one of claims 1 to 4, wherein the first hard coat layer contains a binder and particles having an average particle size of 1.0 µm or more and 8.0 µm or less. An image display cell, a cover window arranged on the viewing side of the image display cell, and the optical film set according to any one of claims 1 to 5,
The first optical film of the optical film set is arranged on the viewing side of the cover window with the first antireflection layer facing the viewing side,
The image display device, wherein the second optical film of the optical film set is arranged on the image display cell side of the cover window with an air layer interposed therebetween, with the second antireflection layer facing the viewing side. 7. The image display device according to claim 6, wherein the air layer has a thickness of 0.1 mm or more and 2.0 mm or less.

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