JP7128571B2 - Composition for low refractive index layer - Google Patents

Description

The present invention relates to an antireflection optical film and a composition for a low refractive index layer.

In products with display screens such as mobile phones, tablet terminals, video cameras, digital cameras, and equipment for automobiles, the display screen portion is composed of a combination of liquid crystal panels, organic EL panels, and the like.
The display screens of such products are required to have anti-reflection properties in order to make the displayed screens easier to see. High scratch resistance that does not stick is required.
In addition, display screens of image display devices in recent years have become increasingly high-definition, and it is also required to obtain a more excellent sense of design (glossy black display, etc.).

On the other hand, for example, Patent Document 1 discloses an antireflection molded product having an antireflection layer with an average surface roughness Ra of 2.0 to 150 nm.
Such a conventional antireflection layer is manufactured using a mold having a specific shape so that the value of the average surface roughness Ra is controlled within a predetermined range.
However, even an antireflection layer having such an average surface roughness cannot be said to have sufficient antifouling properties and scratch resistance. A film was wanted.

Japanese Patent Application Laid-Open No. 2002-205317

In view of the above-mentioned current situation, the present invention provides a low refractive index layer composition capable of forming a low refractive index layer having extremely excellent antifouling properties and scratch resistance and excellent antireflection performance, and an extremely excellent An object of the present invention is to provide an antireflection optical film which has excellent antireflection performance as well as antifouling properties and scratch resistance.

The present invention provides an antireflection optical film having at least a hard coat layer and a low refractive index layer laminated on one surface of the hard coat layer, wherein the hard coat layer side of the low refractive index layer and On the opposite side surface, when the root-mean-square roughness Rq, the ten-point average roughness Rz, and the maximum height roughness Ry are measured with a cutoff wavelength of 2.5 mm, the Rq is 0.010 μm or more and 0.01 μm or more. 050 μm or less, Rz is 0.050 μm or more and 0.250 μm or less, and Ry is 0.050 μm or more and 0.350 μm or less.

The antireflection optical film of the present invention has a root-mean-square roughness Rq and a ten-point average roughness at cutoff wavelengths of 2.5 mm and 0.25 mm on the surface of the low refractive index layer opposite to the hard coat layer side. When Rz and maximum height roughness Ry were measured, the ratio of the values at the cutoff wavelength of 2.5 mm and the values at the cutoff wavelength of 0.25 mm of the above Rq, Rz and Ry (the value at the cutoff wavelength of 2.5 mm /value at a cutoff wavelength of 0.25 mm) is preferably 1.00 or more and 2.00 or less.
The hard coat layer preferably contains 10 parts by mass or more and 300 parts by mass or less of inorganic fine particles with respect to 100 parts by mass of the binder component.
Further, it is preferable that a transparent optical adhesive film is laminated on the side of the hard coat layer opposite to the low refractive index layer.
Further, it is preferable that an anchor layer and an adhesive layer are laminated via the anchor layer on the side of the hard coat layer opposite to the low refractive index layer.
Further, in the antireflection optical film of the present invention, the total thickness of the low refractive index layer and the hard coat layer is preferably 3 μm or more and 15 μm or less. The total thickness of the film and the total thickness of the low refractive index layer, hard coat layer, anchor layer and adhesive layer are preferably 8 μm or more and 30 μm or less.
In addition, a release film is attached to the side opposite to the hard coat layer side of the low refractive index layer, and the peeling force between the low refractive index layer and the release film is 10 mN / 25 mm or more and 500 mN / 25 mm The following are preferable.

The present invention also provides a composition for a low refractive index layer containing hollow particles and a binder resin, which contains 20% by mass or more of an alkylene oxide-modified (meth)acrylate compound based on 100% by mass of solid content of the binder resin. A composition for a low refractive index layer characterized by:
In the composition for low refractive index layer of the present invention, the alkylene oxide-modified (meth)acrylate compound is preferably an ethylene oxide-modified (meth)acrylate-based compound and/or a propylene oxide-modified (meth)acrylate-based compound. .
Moreover, it is preferable that the number of functional groups of the alkylene oxide-modified (meth)acrylate compound is 6 or less.
Further, it is preferable that the hollow particles are contained in an amount of 40 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin, and the hollow particles are preferably hollow silica fine particles.
The present invention will be described in detail below.

As a result of intensive studies, the present inventors have found that in a conventional antireflection optical film provided with an antireflection layer, when the unevenness on the outermost surface (for example, the low refractive index layer) on the display screen side is touched with a finger, The present inventors have found that the residual dust results in insufficient antifouling performance, and that the scratch resistance is sometimes deteriorated due to the dust being caught on the irregularities.
That is, the antireflection optical film of the present invention has extremely high antifouling properties and excellent scratch resistance because the surface of the low refractive index layer is formed with an uneven shape that is controlled with extremely high precision. It also has prevention performance.
In addition, the composition for a low refractive index layer of the present invention can suitably form a low refractive index layer in which such an uneven shape controlled with extremely high accuracy is formed.

First, the composition for low refractive index layer of the present invention will be described.
The low refractive index layer composition of the present invention contains hollow particles and a binder resin.
The above-mentioned hollow particles refer to particles having an outer shell layer, the interior of the particle surrounded by the outer shell layer being porous or hollow, and the interior of the particle containing air.
The low refractive index layer composition of the present invention can lower the refractive index of the low refractive index layer to be formed by containing the hollow fine particles.
The refractive index of the hollow particles is preferably 1.44 or less, particularly preferably 1.40 or less, from the viewpoint of imparting low refractive index properties.

The outer shell layer of the hollow particles may be inorganic or organic, and examples thereof include those made of metals, metal oxides, resins, silica, and the like.
The hollow particles are preferably hollow silica particles whose outer shell layer is made of silica. When the outer shell layer is silica, the silica may be crystalline, sol-like, or gel-like.
The shape of the hollow particles may be any of nearly spherical, chain-like, needle-like, plate-like, flake-like, rod-like, fibrous, etc., such as true spheres, spheroids, and polyhedral shapes that can be approximated to spheres. Among them, a spherical shape and a substantially spherical shape are preferable, and a spheroidal shape or a true spherical shape is particularly preferable.

The particle size of the hollow particles is not particularly limited, but the average particle size defined as the 50% particle size (d50 median diameter) when the particle size distribution measured by the dynamic light scattering method is represented by the volume cumulative distribution ( Hereinafter, sometimes simply referred to as "average particle size (d50)") is preferably 10 nm or more and 120 nm or less, more preferably 40 nm or more and 100 nm or less, and still more preferably 50 nm or more and 80 nm or less.
When the average particle diameter (d50) of the hollow particles is equal to or less than the upper limit, the obtained low refractive index layer has excellent transparency. It is easy to disperse uniformly in the inside, and it becomes easy to impart low refractive index properties to the low refractive index layer. Further, when the average particle diameter (d50) of the hollow particles is within the above range, it becomes easy to make the uneven shape of the uneven surface of the low refractive index layer have a specific maximum height difference.
The average particle size (d50) is the average particle size (d50) of the primary particle size if the hollow particles are not aggregated, and the secondary particle size if the hollow particles are aggregated particles. Let it be the average particle size (d50).
The average particle size (d50) can be measured using a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd. or a Nanotrac particle size analyzer.

As the hollow particles, it is preferable to use a combination of two or more kinds of hollow particles having different average particle diameters (d50) from the viewpoint of improving the scratch resistance of the low refractive index layer. ) is 40 to 60 nm, and hollow fine particles B having an average particle diameter (d50) larger than the average particle diameter (d50) of the hollow fine particles A and 50 to 80 nm are preferably used in combination. When two or more types of hollow particles having different average particle diameters (d50) are used, it is preferable that the hollow particles have uniform particle diameters. d50) is preferably 20% or less, more preferably 10% or less. Abrasion resistance can be further improved by using a combination of two or more types of hollow particles having small variations in particle size and different average particle sizes (d50).
In addition, the ratio (X/Y) of the content of the hollow fine particles A (X parts by mass) and the content of the hollow fine particles B (Y parts by mass) in the total solid content of the composition for the low refractive index layer is preferably 0.5-2.

In addition, the average particle diameter of the hollow particles that can be measured from a TEM photograph or an SEM photograph of the low refractive index layer after curing is not particularly limited, but is preferably 10 nm to 120 nm, and is preferably 40 nm to 100 nm. is more preferable, and 50 nm to 80 nm is even more preferable.
The method for measuring the average particle size is, for example, observing particles using a TEM photograph or SEM photograph taken at a magnification of 500,000 to 2,000,000 times, and the average value of the particle sizes of 100 observed particles is taken as the average particle size. can do. In addition, when the shape of the hollow particles is a shape that includes the concept of an aspect ratio, such as a spheroid shape or rod shape having a short diameter and a long diameter, the particle diameter of the hollow particles is the average value of the short diameter and long diameter. .
In addition, the average particle size measured from the TEM photograph or SEM photograph is the average particle size of the primary particle size if the hollow particles are particles that do not aggregate, and if the hollow particles are aggregate particles, the secondary particles It is assumed to be the average particle size of the diameter.

Specific examples of the hollow particles include composite oxide sols and hollow silica fine particles disclosed in JP-A-7-133105 and JP-A-2001-233611. Among them, hollow silica particles prepared using the technique disclosed in JP-A-2001-233611 are preferable. In addition, since the hollow particles have high hardness, the layer strength of the low refractive index layer is improved, and the refractive index can be adjusted within the range of about 1.20 to 1.44. Microparticles are preferred.

The content of the hollow particles is preferably 40 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin described later. When the content of the hollow particles is at least the lower limit, it is easy to impart low refractive index properties, and when it is at most the upper limit, the film strength of the low refractive index layer to be formed can be improved. More preferably, the hollow particles are 100 parts by mass or more and 150 parts by mass or less.

The composition for a low refractive index layer of the present invention contains 20% by mass or more of an alkylene oxide-modified (meth)acrylate compound based on 100% by mass of solid content of the binder resin. If it is less than 20% by mass, when the release film is attached to the surface of the formed low refractive index layer, the peel strength between the release film and the low refractive index layer will be insufficient.
The content of the alkylene oxide-modified (meth)acrylate compound is preferably 50 parts by mass or more with respect to 100 parts by mass of the binder resin in 100% by mass of solid content of the binder resin.
In addition, in this specification, (meth)acrylate represents acrylate or methacrylate.

The alkylene oxide-modified (meth)acrylate-based compound is preferably an ethylene oxide (EO)-modified (meth)acrylate-based compound and/or a propylene oxide (PO)-modified (meth)acrylate-based compound. PO-modified (meth)acrylate compounds are more preferred in consideration of the peeling force between the layer and the low refractive index layer.

Moreover, it is preferable that the number of functional groups of the alkylene oxide-modified (meth)acrylate compound is 6 or less.
If the number of functional groups exceeds 6, the peel strength between the release film and the low refractive index layer may be insufficient.

Binder resins other than the above alkylene oxide-modified (meth)acrylate compounds include, for example, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol (meth)tetraacrylate, dipentaerythritol penta(meth) ) polymers or copolymers of at least one monomer selected from the group consisting of acrylates, trimethylolpropane tri(meth)acrylates, and dipentaerythritol tetra(meth)acrylates.

A solvent is usually used in the composition for low refractive index layer of the present invention in order to improve coatability. The solvent may be appropriately selected from those that do not react with the components in the composition for the low refractive index layer and can uniformly dissolve or disperse the components. Examples of such solvents include various ketone-based solvents such as methyl isobutyl ketone and methyl ethyl ketone.
The content of the solvent is preferably 60 to 98% by mass, more preferably 70 to 97% by mass, based on the total amount of the low refractive index layer composition.
Further, the composition for low refractive index layer may contain a conventionally known photopolymerization initiator.

The composition for a low refractive index layer of the present invention having such a composition can suitably form a low refractive index layer having a low refractive index and extremely excellent flatness. The antifouling performance and scratch resistance are extremely excellent, and the optical film provided with the low refractive index layer can be made excellent in antireflection performance.

In addition, since an optical film having a low refractive index layer formed using the composition for a low refractive index layer of the present invention can be made more excellent in antireflection performance, the high refractive index layer can be used as described above. It is preferably formed adjacent to the low refractive index layer.
Examples of the high refractive index layer include layers having a higher refractive index than the low refractive index layer.

Further, the refractive index of the high refractive index layer may be higher than the refractive index of the low refractive index layer. Specifically, it is preferably in the range of 1.5 to 1.7. .
Further, when the high refractive index layer is provided between a hard coat layer and a low refractive index layer described later, the refractive index of the high refractive index layer is higher than the refractive index of the low refractive index layer, and , preferably higher than the refractive index of the hard coat layer.

The high refractive index layer is not particularly limited as long as it satisfies the above refractive index range and has transparency. Examples thereof include those obtained by curing a composition for a high refractive index layer containing index fine particles. Among them, it is preferable to use a composition obtained by curing a composition for a high refractive index layer containing an ionizing radiation curable resin and high refractive index fine particles, because adjustment of the refractive index is easy.

The ionizing radiation curable resin used for the high refractive index layer is not particularly limited as long as it satisfies the above refractive index range and can obtain a transparent high refractive index layer. It is appropriately selected from the viewpoint of film strength and the like.
Examples of the ionizing radiation curable resin include ultraviolet curable resins and electron beam curable resins, among which ultraviolet curable resins are preferred.

Specific examples of the ionizing radiation curable resin include ionizing radiation used in high refractive index layers described in JP-A-2013-142817, JP-A-2012-150226, JP-A-2011-170208, and the like. A radiation curable resin and the like can be mentioned.

The high refractive index fine particles are not particularly limited as long as they have a higher refractive index than the ionizing radiation curable resin and can provide a high refractive index layer that satisfies the above refractive index range. The fine particles preferably have a refractive index of about 1.5 to 2.8.
Examples of such high refractive index fine particles include metal oxide fine particles, specifically zirconium oxide, antimony oxide, antimony tin oxide, indium tin oxide, phosphorus tin compound, gallium zinc oxide, -Al ₂ O ₅ , γ-Al ₂ O ₅ , barium titanate, titanium oxide, cerium oxide, tin oxide, aluminum zinc oxide, gallium zinc oxide, zinc antimonate and the like.

Moreover, the high refractive index fine particles may be surface-treated. By subjecting the high refractive index fine particles to a surface treatment, the affinity with the ionizing radiation curable resin and solvent is improved, the high refractive index fine particles are uniformly dispersed, and aggregation of the high refractive index fine particles is less likely to occur. It is possible to suppress a decrease in the transparency of the high refractive index layer, a decrease in the applicability of the composition for the high refractive index layer, and a decrease in the coating strength of the composition for the high refractive index layer.
Examples of the surface-treated high refractive index fine particles include those described in JP-A-2013-142817.
Also, the high refractive index fine particles may be reactive fine particles having photocurable groups on their surfaces.

The average particle size of the fine particles of high refractive index may be any value as long as it is possible to form a high refractive index layer having a uniform thickness. It is in the range of 100 nm or less, more preferably in the range of 10 nm or more and 80 nm or less.
If the average particle size of the high refractive index fine particles is within the above range, the high refractive index fine particles can be dispersed in a favorable state without impairing the transparency of the high refractive index layer. As long as the average particle size of the high refractive index fine particles is within the above range, the average particle size may be either the primary particle size or the secondary particle size. may
Here, the average particle size of the high refractive index fine particles refers to the average value of 20 particles observed in a transmission electron microscope (TEM) photograph of the cross section of the high refractive index layer.
The shape of such high refractive index fine particles is not particularly limited, and examples thereof include spherical, chain-like, needle-like, and the like.

The contents of the ionizing radiation curable resin and the high refractive index fine particles in the high refractive index layer are not particularly limited, and are appropriately set so that the refractive index of the high refractive index layer as a whole satisfies the above refractive index range.

When an ultraviolet curable resin is used as the ionizing radiation curable resin, the high refractive index layer may contain a photopolymerization initiator. Further, the high refractive index layer may contain various additives according to desired physical properties. The same photopolymerization initiators and the same as those for the low refractive index layer can be used. Examples of the additives include dispersing aids, weather resistance improvers, wear resistance improvers, polymerization inhibitors, and cross-linking agents. , infrared absorbers, adhesion improvers, antioxidants, leveling agents, thixotropic agents, coupling agents, plasticizers, antifoaming agents, fillers and the like.

Although the thickness of the high refractive index layer varies depending on the refractive index, it is preferably, for example, within the range of 50 nm or more and 200 nm or less.

As a method for forming the high refractive index layer, for example, a composition for a high refractive index layer obtained by mixing the above-described ionizing radiation curable resin, high refractive index fine particles, a solvent, a photopolymerization initiator and various additives is applied. and a method in which the formed coating film is cured by irradiation with ionizing radiation.

The present invention provides an antireflection optical film having at least a hard coat layer and a low refractive index layer laminated on one surface of the hard coat layer, wherein the hard coat layer side of the low refractive index layer and On the opposite surface (hereinafter also referred to as the surface), the cutoff wavelength is 2.5 mm, and the root mean square roughness Rq, the ten point average roughness Rz, and the maximum height roughness Ry are measured. , 0.010 μm or more and 0.050 μm or less, the Rz is 0.050 μm or more and 0.250 μm or less, and the Ry is 0.050 μm or more and 0.350 μm or less. But also.

When the low refractive index layer satisfies the requirements for Rq, Rz and Ry, the antireflection optical film of the present invention has an extremely flat surface of the low refractive index layer.
Here, conventional antireflection optical films provided with a low refractive index layer exhibit antifouling performance by adding a leveling agent to the low refractive index layer or a hard coat layer described later. Since the antifouling optical film can exhibit extremely excellent antifouling performance due to the flatness of the surface of the low refractive index layer, it is not necessary to include a leveling agent in the low refractive index layer or the like.

Conventionally, even if the surface of a low refractive index layer looks flat to the naked eye, it actually has various extremely fine irregularities. That is, although it is visually flat, the low refractive index layer is formed by actually transferring the low refractive index layer adhered to the release film to the transferred material by a transfer method as described later. As a result, the transfer surface of the completed low refractive index layer sometimes caused a difference in antifouling property and scratch resistance.
The inventors of the present application have found that this is caused by fine irregularities that cannot be visually recognized on the surface of the low refractive index layer. Then, regarding the uneven shape of the surface of the low refractive index layer, the root mean square roughness Rq, the ten point average roughness Rz, and the maximum height roughness Ry, which are parameters related to the height direction of the surface of the low refractive index layer. are controlled so as to fall within a predetermined range at a cutoff wavelength of 2.5 mm, so that the flatness of the surface of the low-refractive-index layer makes it possible to exhibit extremely excellent antifouling performance and scratch resistance.
In addition, the antireflection optical film of the present invention exhibits excellent antifouling properties without using additives such as fluorine materials. can be expressed.

The above Rq represents the root-mean-square roughness. Specifically, as shown in FIG. 1 and obtained by arithmetically averaging Rq′ obtained at a plurality of sampling lengths. The above Rq can also be determined according to ISO 4287-1984 or ISO 4287-1997, and specifically, it is measured using a surface roughness measuring instrument (SE3400, SE3500, SE4000, manufactured by Kosaka Laboratory). can.
The above Rq is a representative value representing the average height of the protrusions on the surface of the low refractive index layer.
In the antireflection optical film of the present invention, the root mean square roughness Rq of the surface of the low refractive index layer is 0.010 μm or more and 0.050 μm or less at a cutoff wavelength of 2.5 mm. If it is less than 0.010 μm, the smoothness is good, and it is preferable for scratch resistance and antifouling properties. The smoothness becomes insufficient, and the scratch resistance and antifouling properties tend to decrease. A preferable upper limit of Rq is 0.040 μm, and a more preferable upper limit is 0.030 μm.

The above Rz is the 10-point average roughness of JIS B0601-1994, and the concave portion from the lowest to the 5th and the convex portion from the highest to the 5th which cannot be seen because it is smoothed out by the average value like Rq Since it is the ten-point average roughness value obtained by adding the above, it is the average value in the direction of the maximum existing on the plane.
In the antireflection film of the present invention, the surface of the low refractive index layer has a ten-point average roughness Rz of JIS B0601-1994 of 0.050 μm or more and 0.250 μm or less at a cutoff wavelength of 2.5 mm. If it is less than 0.050 µm, the smoothness is good, and although it is preferable for antifouling properties, it tends to be difficult to peel off from the release film during actual production, and if it exceeds 0.250 µm, the smoothness is insufficient. As a result, the scratch resistance and antifouling properties tend to decrease, and it causes optical defects in the antireflection film. A preferable upper limit of Rz is 0.200 μm, and a more preferable upper limit is 0.150 μm.

The parameters representing the average flatness of the surface of the low refractive index layer may be the above Rq and Rz. It is necessary to limit such protruding asperities, as such asperities can cause optical defects in the product and thus reduce its scratch resistance. Therefore, in the present invention, the range of Ry is controlled as the limit value of the unevenness on the surface of the low refractive index layer.
The above Ry is the maximum height roughness of JIS B0601-1994, and is a value obtained by measuring the distance between the peak line of the convex portion and the bottom line of the concave portion in the direction of the longitudinal magnification of the roughness curve.
In the antireflection film of the present invention, the surface of the low refractive index layer has a maximum height roughness Ry of JIS B0601-1994 of 0.050 μm or more and 0.350 μm or less at a cutoff wavelength of 2.5 mm. If it is less than 0.050 μm, the smoothness is good and it is preferable for antifouling properties, but it tends to be difficult to peel off from the release film during actual production. It becomes an optical defect of the protective optical film and causes deterioration of scratch resistance. A preferable upper limit of Ry is 0.300 μm, and a more preferable upper limit is 0.250 μm.

In addition, as in the antireflection optical film of the present invention, it is extremely difficult to achieve excellent antifouling properties and scratch resistance simply by controlling the uneven shape of the surface of the low refractive index layer without adding any additives. It should be flat without resistance. In other words, in the antireflection optical film of the present invention, it is preferable that the surface of the low refractive index layer has no difference in unevenness between the low-frequency component and the high-frequency component.
Here, in the measurement of the irregular shape of the surface of the low refractive index layer, when the cutoff wavelength is set to 0.25 mm, a narrow range is measured. On the other hand, when the cutoff wavelength is 2.5 mm, a wider range is measured than when the cutoff wavelength is 0.25 mm, and it is considered that the low-frequency component of surface flatness is observed.
The low-frequency component is like a basic large undulation that constitutes the surface of the low refractive index layer, and the small unevenness that slightly exists on it is the high-frequency component.

The antireflection optical film of the present invention has a root mean square roughness Rq according to ISO 4287-1984 or 1997 with cutoff wavelengths of 2.5 mm and 0.25 mm on the surface of the low refractive index layer, When the ten-point average roughness Rz and the maximum height roughness Ry of JIS B0601-1994 are measured, the values at the cutoff wavelength of 2.5 mm and the values at the cutoff wavelength of 0.25 mm of the above Rq, Rz and Ry (value at a cutoff wavelength of 2.5 mm/value at a cutoff wavelength of 0.25 mm) (hereinafter also referred to as cutoff ratio) are preferably 1.00 or more and 2.00 or less. When the cutoff ratios of Rq, Rz and Ry are all 1.00 or more and 2.00 or less, the antifouling property and scratch resistance of the antireflection optical film of the present invention can be made extremely excellent. can. The cutoff ratios of Rq, Rz and Ry are more preferably 1.70 or less, still more preferably 1.50 or less.

A low refractive index layer that satisfies the above relationships of Rq, Rz and Ry can be suitably formed by using the composition for a low refractive index layer of the present invention described above. A specific method for forming the low refractive index layer will be described in detail later.

The hard coat layer preferably contains 10 to 300 parts by mass of inorganic fine particles with respect to 100 parts by mass of the binder component. If the amount is less than 10 parts by mass, the hard coat performance of the antireflection optical film of the present invention will be insufficient, and if it exceeds 300 parts by mass, the hard coat layer will become rigid, have no elongation, and easily crack. There is A more preferable lower limit for the content of the inorganic fine particles is 20 parts by mass, and a more preferable upper limit is 150 parts by mass.
Further, the inorganic particles are preferably reactive silica fine particles when increasing the hardness, and preferably high refractive index particles when increasing the refractive index. Fine particles of zirconia, antimony pentoxide, alumina, ATO, ITO, _TiO2 , etc. are used as the high refractive index particles.

In the antireflection optical film of the present invention, it is preferable that a transparent optical adhesive film is laminated on the side of the hard coat layer opposite to the low refractive index layer. By laminating the transparent optical pressure-sensitive adhesive film, it is possible to produce an antireflection optical film that is excellent in transferability and adhesion to a transfer material.
Examples of the transparent optical pressure-sensitive adhesive film include a structure in which an optical pressure-sensitive adhesive layer is formed on a base material. , weather resistance, heat resistance, and transparency, acrylic resins are used. Monomers constituting the acrylic resin include, for example, alkyl acrylates such as ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, and benzyl acrylate, Methacrylic acid alkyl esters such as butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, ethyl methacrylate, and vinyl acetate, vinyl propionate, vinyl ether, styrene, acrylonitrile, methacrylonitrile, etc. A group-containing compound may be copolymerized. Furthermore, in order to improve the adhesion durability performance and suppress the generation of outgassing, it is preferable that the main component of the optical pressure-sensitive adhesive is an acrylic resin, have a weight average molecular weight of 500,000 or more, and have a polydispersity of 5 or less. In addition, when an adhesive layer is used for bonding various optical films, if the difference in refractive index between the optical film and the adhesive layer is large, interfacial reflection of light occurs at the interface between the optical film and the adhesive layer. A refractive index adjuster is added to adjust the refractive index. In addition, if necessary, cross-linking agents, catalysts, UV absorbers, antioxidants, coloring pigments, glass beads, fillers, flame retardants, antibacterial agents, light stabilizers, coloring agents, flow improvers, lubricants, anti-blocking agents agents, antistatic agents, cross-linking aids and the like can be blended. These may be used alone or in combination of two or more. Any cross-linking agent can be used without particular limitation as long as it does not interfere with the required properties. Examples include polyisocyanates, chelates, epoxy resins, melamine resins, and amide resins.

Although the thickness of the pressure-sensitive adhesive layer for optics may be set arbitrarily, it is preferably 3 μm or more and 30 μm or less.
The base material on which the optical pressure-sensitive adhesive layer is provided is not particularly limited. There are resin sheets and norbornene resin sheets. Although the thickness of the sheet is not particularly limited, it is preferably less than 500 μm, more preferably 10 μm or more and 50 μm or less. For protection of the optical pressure-sensitive adhesive layer, it can be used by laminating with a release liner or the like, if necessary. The release liner is not particularly limited, but examples thereof include PET film, olefin resin film, PPS resin film, TAC film, acrylic resin film, and those subjected to release treatment. Although the thickness of the release liner is not particularly limited, it is preferably less than 500 μm, more preferably 10 μm or more and 50 μm or less.

In the antireflection optical film of the present invention, it is preferable that an anchor layer and an adhesive layer are laminated via the anchor layer on the side of the hard coat layer opposite to the low refractive index layer.

The anchor layer is a layer provided as desired in order to improve adhesion between the hard coat layer and the adhesive layer.
The anchor layer includes a two-liquid curable urethane resin, a thermosetting urethane resin, a melamine resin, a cellulose ester resin, a chlorine-containing rubber resin, a chlorine-containing vinyl resin, an acrylic resin, an epoxy resin, and a vinyl copolymer. Using a coalescing resin or the like, for example, coating on the hard coat layer formed as described above by a coating method such as a gravure coating method, a roll coating method, a comma coating method, a gravure printing method, a screen printing method, etc. can be formed by The thickness of the anchor layer is usually about 0.1 μm to 5 μm, preferably about 1 μm to 5 μm.

The adhesive layer is a layer formed for transferring to a resin molding with good adhesiveness. A heat-sensitive or pressure-sensitive resin suitable for the material of the resin molding is appropriately used for this adhesive layer. For example, when the material of the resin molding is acrylic resin, it is preferable to use acrylic resin. If the material of the resin molding is polyphenylene oxide/polystyrene resin, polycarbonate resin, or styrene resin, use acrylic resin, polystyrene resin, polyamide resin, etc. that have affinity with these resins. is preferred. Furthermore, when the material of the resin molding is polypropylene resin, it is preferable to use chlorinated polyolefin resin, chlorinated ethylene-vinyl acetate copolymer resin, cyclized rubber, and coumarone-indene resin.
Methods for forming the adhesive layer include coating methods such as gravure coating and roll coating, and printing methods such as gravure printing and screen printing.
It is preferable that the thickness of the adhesive layer is usually about 0.1 μm or more and 5 μm or less.

Further, it is preferable that the total thickness of the low refractive index layer and the hard coat layer is 3 μm or more and 15 μm or less. If it is less than 3 μm, the hard coat performance may be insufficient, and if it exceeds 15 μm, it may become rigid and easily crack.

Further, the total thickness of the low refractive index layer, hard coat layer and transparent optical adhesive film is preferably 8 μm or more and 30 μm or less. If the thickness is less than 8 μm, the adhesive strength may be weak, and the transfer described below may not be possible.
Further, the total thickness of the low refractive index layer, hard coat layer, anchor layer and adhesive layer is preferably 8 μm or more and 30 μm or less. If the thickness is less than 8 μm, the adhesive strength may be weak, and the transfer described below may not be possible.

Moreover, it is preferable that a release film is attached to the surface of the low refractive index layer, and the peeling force between the low refractive index layer and the release film is 10 mN/25 mm or more and 500 mN/25 mm or less. .
Suitable release films include untreated polyethylene terephthalate (PET) films.
As will be described later, the low refractive index layer is preferably transferred to a transfer target by a transfer method with the release film attached, and then the release film is peeled off, but the peel force is 10 mN / If it is less than 25 mm, the release film may peel off during the transfer method, and if it exceeds 500 mN/25 mm, the release film may not be peeled off during the transfer method.
A more preferable lower limit of the peel force is 20 mN/25 mm, and a more preferable upper limit is 300 mN/25 mm.
The peeling force between the low refractive index layer and the peeling film can be measured according to JIS Z 0237.

The antireflection optical film of the invention can be formed by a transfer method.
That is, a coating film is formed on a release film using the composition for low refractive index layer of the present invention, and semi-cured by, for example, ultraviolet irradiation. Then, a coating film is formed using the composition for a hard coat layer on the semi-cured coating film of the composition for a low refractive index layer, for example, by completely curing by ultraviolet irradiation, a release film and a low refractive index layer are formed. It is possible to obtain an antireflection optical film that can be suitably peeled at the interface with the index layer.
In addition, by forming the film by a transfer method, it is possible to reduce the weight of the entire film, and even if the design of the display device is a curved surface or a folding type, cracks are unlikely to occur and the film can be easily followed. Are better.
The release film may be a known resin film such as a polyethylene terephthalate film, or may be a plate-shaped body such as glass. Furthermore, the surface of the release film on which the low refractive index layer is provided may be surface-treated, but from the viewpoint of preventing an increase in the reflectance of the low refractive index layer due to the effect of the treatment agent on the surface. The surface of the release film on which the low refractive index layer is provided is preferably not surface-treated.
In addition, when the release film has a cutoff wavelength of 2.5 mm and the root-mean-square roughness Rq, the ten-point average roughness Rz, and the maximum height roughness Ry are measured, the Rq is 0.010 μm. It is preferably 0.050 μm or less, more preferably 0.040 μm or less, still more preferably 0.035 μm or less, and the Rz is preferably 0.070 μm or more and 0.350 μm or less, more preferably It is 0.250 μm or less, more preferably 0.200 μm or less, and the Ry is preferably 0.100 μm or more and 0.450 μm or less, more preferably 0.350 μm or less, and still more preferably 0.250 μm or less. is.
Rq, Rz and Ry on the surface of the release film are the same as those described for the low refractive index layer.

The amount of ultraviolet irradiation for semi-curing the coating film of the low refractive index layer composition is preferably 20 mJ/cm ² or more and 75 mJ/cm ² or less. If it is less than ²⁰ mJ/cm ² , the low refractive index layer may not be formed.
The amount of UV irradiation when curing the coating film of the hard coat layer composition is preferably 20 mJ/cm ² or more and 150 mJ/cm ² or less. If it is less than 20 mJ/cm ² , the hard coat layer may not be formed, and if it exceeds 150 mJ/cm ² , it may become rigid and easily crack.
When the UV irradiation dose for semi-curing the coating film of the composition for the low refractive index layer is 20 mJ/cm ² , the UV irradiation dose for curing the coating film of the composition for the hard coat layer is It is preferably 20 mJ/cm ² or more.
Further, when the UV irradiation dose for semi-curing the coating film of the composition for the low refractive index layer is 50 mJ/cm ² , the UV irradiation dose for curing the coating film of the composition for the hard coat layer is It is preferably 50 mJ/cm ² or more.
When the UV irradiation dose for semi-curing the coating film of the composition for the low refractive index layer is 75 mJ/cm ² , the UV irradiation dose for curing the coating film of the composition for the hard coat layer is 100 mJ/cm 2 . cm ² or more is preferable.
By forming a low refractive index layer and a hard coat layer by irradiating ultraviolet rays under the conditions described above, it is possible to produce an antireflection optical film that can be suitably peeled off at the interface between the release film and the low refractive index layer. .
A transparent optical adhesive film may be laminated on the side of the hard coat layer opposite to the low refractive index layer.

As a specific method of transferring the above-described antireflection optical film of the present invention to a transfer target, for example, a transparent antireflection optical film of the present invention is coated on a polarizer (or a layer made of a PVA-based adhesive). An optical adhesive film is laminated, the antireflection optical film of the present invention is pressed with a roller, the transparent optical adhesive film is attached to a polarizer (or a layer made of a PVA-based adhesive), and the release film is peeled off after drying. There is a method to make

The antireflection optical film of the present invention preferably has a hardness of B or more, more preferably 2H or more in a pencil hardness test (load 4.9 N) according to JIS K5600-5-4 (1999).

Moreover, the antireflection optical film of the present invention preferably does not cause scratches in a scratch resistance test in which, for example, #0000 steel wool (manufactured by Bonstar) is rubbed back and forth at a friction load of 100 g/cm ² for 10 reciprocations.

Further, the antireflection optical film of the present invention preferably has a reflection Y value of 1.5% or less. If the reflection Y value exceeds 1.5%, the antireflection performance of the antireflection optical film of the present invention may become insufficient. A more preferable upper limit of the reflection Y value is 1.0%.

The antireflection optical film of the present invention is excellent in antifouling properties and scratch resistance as well as in antireflection properties, and is therefore suitable for display screens of image display devices, back surfaces of camera lenses, and the like. can be used.
The image display device using the antireflection optical film of the present invention is not particularly limited, but display devices such as mobile terminals equipped with a touch sensor such as smartphones and tablet terminals and automobile equipment are particularly suitable.
Examples of the camera lens include camera lenses mounted on smartphones and tablet terminals, and lenses of video cameras and digital cameras.
When the antireflection film of the present invention has the above-described anchor layer and adhesive layer, it can be suitably used for in-vehicle use (in-mold molding).

Further, the image display device may be a liquid crystal display device (LCD), PDP, FED, ELD (organic EL, inorganic EL), CRT, or the like.

The LCD includes a transmissive display and a light source device for illuminating the transmissive display from behind. When the image display device is an LCD, the antireflection optical film of the present invention is formed on the surface of this transmissive display.

When the image display device is an LCD, the light source of the light source device illuminates from the polarizer side. In the STN-type liquid crystal display device, a retardation plate may be inserted between the liquid crystal display element and the polarizer. An adhesive layer may be provided between each layer of the liquid crystal display device, if necessary.

The PDP includes a front glass substrate and a rear glass substrate facing the front glass substrate, with a discharge gas sealed between them. When the image display device is a PDP, the surface of the front glass substrate or its front plate (glass substrate or film substrate) is provided with the antireflection optical film described above.

The image display device is an ELD device in which a light-emitting body such as zinc sulfide or a diamine substance that emits light when a voltage is applied is vapor-deposited on a glass substrate and the voltage applied to the substrate is controlled to perform display, or an electric signal is converted into light. It may also be an image display device such as a CRT that converts and produces an image visible to the human eye. In this case, the above-described antireflection optical film is provided on the outermost surface of each display device as described above or on the surface of its front plate.

In any case, the antireflection optical film of the present invention can be used for displays of televisions, computers, etc., and lenses for cameras. In particular, it can be suitably used for high-definition image displays such as liquid crystal panels, PDPs, ELDs, touch panels, and electronic papers, and camera lenses mounted on cholera.

Since the antireflection optical film of the present invention has the structure described above, it has extremely excellent antifouling properties and scratch resistance, and has a low refractive index that enables the formation of a low refractive index layer that is also excellent in antireflection performance. It is possible to provide a composition for a layer and an antireflection optical film having extremely excellent antifouling properties and scratch resistance and also excellent antireflection performance. Therefore, the antireflection optical film of the present invention can be used for displays such as liquid crystal displays (LCD), plasma displays (PDP), electroluminescence displays (ELD), electronic paper, tablet terminals, especially mobile terminals and cameras installed therein. It can be suitably used for lenses.

FIG. 4 is an explanatory diagram of Rq;

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.
In the text, "parts" and "%" are based on mass unless otherwise specified.

(Coating liquid for low refractive index layer)
Propylene oxide-modified pentaerythritol tetraacrylate (product name “ATM-4P”, manufactured by Shin-Nakamura Chemical Co., Ltd.) 72.5 parts by mass Pentaerythritol triacrylate (PETA) 25.5 parts by mass Hollow silica fine particles (Sururia 4320, solid content 20 %, manufactured by Nikki Shokubai Kasei Co., Ltd., average particle size 60 nm) 700.0 parts by mass Reactive silica fine particles (MIBK-SD, solid content 30%, manufactured by Nissan Chemical Industries, average particle size 10 nm) 83.3 parts by mass Photopolymerization initiation Agent (Irgacure 127, manufactured by Ciba Specialty Chemicals) 7.0 parts by mass Methyl isobutyl ketone 7721.9 parts by mass Propylene glycol monomethyl ether acetate 917.8 parts by mass

(Coating solution for hard coat layer)
Acrylic polymer (product name “BL-2002”, solid content 35%, weight average molecular weight 70,000, acrylic equivalent 265, manufactured by Seiko PMC) 228.6 parts by mass Reactive silica fine particles (product name “ELCOM V8803”, solid 40%, manufactured by Nikki Shokubai Kasei Co., Ltd.) 50.0 parts by mass Fluorine-based compound (product name "F-554", manufactured by DIC) 0.20 parts by mass Photopolymerization initiator (Irgacure 184, Ciba Specialty Chemicals Co., Ltd.) made) 4.0 parts by mass Methyl ethyl ketone 238.2 parts by mass

(Example 1)
First, a polyethylene terephthalate film (product name: Cosmoshine A4100, manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm and having one side subjected to an easy-adhesion treatment was prepared as a release film. The refractive index layer coating liquid was applied so that the film thickness after drying (25° C.×1 minute-50° C.×1 minute) would be 0.1 μm.
Then, using an ultraviolet irradiation device (light source H bulb, manufactured by Fusion UV System Japan), ultraviolet irradiation was performed at an irradiation dose of 20 mJ/cm ² to cure the low refractive index layer, thereby forming a low refractive index layer.
Next, the coating solution for hard coating was applied onto the formed low refractive index layer so that the film thickness after drying (100° C.×1 minute) would be 5 μm. Then, using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb), ultraviolet irradiation is performed at an irradiation dose of 100 mJ / cm ² to cure to form a hard coat layer, antireflection optics for transfer. got the film.

(Example 2)
Example 1 except that the blending amounts in the low refractive index layer coating solution were 50.0 parts by mass of ATM-4P, 70.0 parts by mass of PETA, and 600.0 parts by mass of hollow silica fine particles. In the same manner as above, an antireflection optical film for transfer was obtained.

(Example 3)
Example 1 except that the blending amounts in the low refractive index layer coating solution were 30.0 parts by mass of ATM-4P, 50.0 parts by mass of PETA, and 600.0 parts by mass of hollow silica fine particles. In the same manner as above, an antireflection optical film for transfer was obtained.

(Comparative example 1)
Example 1 except that the blending amounts in the low refractive index layer coating solution were 15.0 parts by mass of ATM-4P, 85.0 parts by mass of PETA, and 600.0 parts by mass of hollow silica fine particles. In the same manner as above, an antireflection optical film for transfer was obtained.

(Comparative example 2)
Same as Example 1, except that the blending amount of the low refractive index layer coating solution was not blended with ATM-4P, 100.0 parts by mass of PETA, and 600.0 parts by mass of hollow silica fine particles. Then, an antireflection optical film for transfer was obtained.

(Comparative Example 3)
600.0 parts by mass of hollow silica microparticles were added to the coating liquid for the low refractive index layer, and polyethylene terephthalate film having a thickness of 50 μm was used as a release film (product name “DIAFOIL T100-50S”, Mitsubishi Plastics Co., Ltd.). An anti-reflection optical film for transfer was obtained in the same manner as in Example 1, except that the product was used.

(Transferability)
A black acrylic plate having a thickness of 100 mm × 100 mm × 1 mm was prepared in advance by laminating a transparent optical adhesive film using a roller, and the obtained antireflection optical film for transfer was placed so that the hard coat layer surface was in contact with the transparent optical adhesive film. In addition, after lamination using a roller, peeling was performed at a speed of about 300 mm/min, and visual evaluation was performed according to the following criteria.
A: Transferred over the entire surface of the black acrylic plate and transferred easily.
Good: Transferred over the entire surface of the black acrylic plate.
Δ: 50% or more of the area of the black acrylic plate is transferred, but there is a portion where the transfer is not performed.
x: Less than 50% of the area of the acrylic plate is transferred.

(reflection Y value)
From the surface of the low refractive index layer, the 5 ° regular reflectance is measured in the wavelength range from 380 to 780 nm using a spectral reflectance measuring instrument "MPC3100" manufactured by Shimadzu Corporation, and then the lightness perceived by the human eye. A value indicating the luminous reflectance calculated by the conversion software (built into MPC3100) was obtained as the reflection Y value.

(Anti-fouling)
After attaching a fingerprint to the surface of each antireflection film obtained, Kimwipe (registered trademark) manufactured by Nippon Paper Crecia Co., Ltd. was wiped off by reciprocating 30 times. was evaluated on the basis of
◎: can be completely wiped off with 30 reciprocations or less (compared to ○, it was easier to wipe off)
○: can be completely wiped off with 30 reciprocations or less ×: cannot be wiped off with 30 reciprocations or less

(Scratch resistance)
The surface of the low refractive index layer of each antireflection film thus obtained was rubbed back and forth 10 times with #0000 steel wool at friction loads of 100 and 200 g/cm ² , and then checked for peeling of the coating film. The presence or absence was visually observed, and the results were evaluated according to the following criteria.
◎: No scratches at 200 g/cm ² ○: No scratches at 100 g/cm ² ×: Scratches at 100 g/cm ²

(Measurement of uneven shape)
Samples obtained from antireflection optical films according to Examples and Comparative Examples were irradiated with the above ultraviolet rays, and Rz, Rq, and Ry on the surface of the polyethylene terephthalate film that was in contact with the hard coat layer after peeling the polyethylene terephthalate film were measured. Along with the measurement, Rz, Rq and Ry on the surface of the protective film in contact with the polyethylene terephthalate film were also measured. The definitions of Rz and Ry are in accordance with JIS B0601-1994, and Rq is in accordance with the formula described in ISO 4287-1984, but can also be similarly measured in ISO 4287-1997. Rz, Rq and Ry were measured using a surface roughness measuring instrument (product name "Surfcorder SE3400, manufactured by Kosaka Laboratory Ltd.) under the following measurement conditions. Rz, Rq and Ry are respectively , and the arithmetic mean value of the values obtained by measuring three times.

Measurement sample:
A sample obtained by pasting an acrylic plate (manufactured by Kuraray Co., Ltd., product name: Comoglass, product number: DFA502K, 10 cm × 10 cm, plate thickness 2 mm) through a transparent adhesive layer (refractive index: 1.55, Panac PDC-S1 50 μm). made.
1) Stylus of surface roughness detector (product name “Surfcorder SE-3400”, manufactured by Kosaka Laboratory, 2 μm standard)
・Tip curvature radius 2 μm, apex angle 90 degrees, material diamond

Measurement conditions used in Examples and Comparative Examples are described below.
A vertical magnification of 100,000 times was suitable for excellent flatness. On the other hand, if the flatness is poor, the amplitude of the waveform appearing during measurement may protrude from the recording paper. Since the longitudinal magnification may affect the measured value, it is preferably 10,000 to 100,000 times when measuring a flat surface, and preferably 100,000 times in the examples. Although the lateral magnification does not affect the measured value, it is sufficient if the waveform is easy to see on the recording paper, and 5 to 50 times is preferable.
The reason why the feed speed is 0.1 mm/s in the case of 0.25 mm is that the measurement range is small, and a slower speed is preferable for stable stylus measurement. On the other hand, in the case of 2.5 mm/s, the lowest speed was 0.5 mm/s in terms of device settings, and the slowest speed was selected in order to stably measure the stylus.

Measurement condition 1 of surface roughness measuring instrument (used in Examples and Comparative Examples 1 and 2)
・Reference length (cutoff value λc of roughness curve): 0.25 mm
・ Evaluation length (reference length (cutoff value λc) × 5): 1.25 mm
・Feeding speed of stylus: 0.1mm/s
・Longitudinal magnification: 100,000 times ・Horizontal magnification: 50 times ・Skid: Not used (no contact with the measurement surface)
・Cutoff filter type: Gaussian ・JIS mode: JIS1994

Measurement condition 2 of surface roughness measuring instrument (used in Examples and Comparative Examples 1 and 2)
・Reference length (cutoff value λc of roughness curve): 2.5 mm
・ Evaluation length (reference length (cutoff value λc) × 5): 12.5 mm
・Feeding speed of stylus: 0.5mm/s
・Longitudinal magnification: 100,000 times ・Horizontal magnification: 50 times ・Skid: Not used (no contact with the measurement surface)
・Cutoff filter type: Gaussian ・JIS mode: JIS1994

Measurement condition 3 of surface roughness measuring instrument (used in Comparative Example 3)
・Reference length (cutoff value λc of roughness curve): 0.25 mm
・ Evaluation length (reference length (cutoff value λc) × 5): 1.25 mm
・Feeding speed of stylus: 0.1mm/s
・Longitudinal magnification: 10,000 times ・Horizontal magnification: 50 times ・Skid: Not used (no contact with the measurement surface)
・Cutoff filter type: Gaussian ・JIS mode: JIS1994

Measurement condition 4 of the surface roughness measuring instrument (used in Comparative Example 3)
・Reference length (cutoff value λc of roughness curve): 2.5 mm
・ Evaluation length (reference length (cutoff value λc) × 5): 12.5 mm
・Feeding speed of stylus: 0.5mm/s
・Longitudinal magnification: 10,000 times ・Horizontal magnification: 50 times ・Skid: Not used (no contact with the measurement surface)
・Cutoff filter type: Gaussian ・JIS mode: JIS1994
The results are shown in Tables 1-3 below.

The antireflection optical film of the present invention is useful for displays such as liquid crystal displays (LCD), plasma displays (PDP), electroluminescence displays (ELD), electronic paper, tablet terminals, etc. It can be suitably used for applications (in-mold molding).

Claims (2)

A low refractive index layer composition for forming a low refractive index layer by a transfer method containing hollow particles and a binder resin, wherein the solid content of the binder resin is 100% by mass, and alkylene oxide-modified (meth)acrylate containing 20% by mass or more of the system compound,
Containing 100 parts by mass or more and 150 parts by mass or less of the hollow particles with respect to 100 parts by mass of the binder resin,
A composition for a low refractive index layer, wherein the alkylene oxide-modified (meth)acrylate compound is propylene oxide-modified pentaerythritol tetraacrylate . 2. The composition for a low refractive index layer according to claim 1 , wherein the hollow particles are hollow silica particles.

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