TWI912385B - Anti-reflective film - Google Patents

Abstract

Issue: To provide an anti-reflective film with excellent scratch resistance and minimal degradation of anti-reflective properties. Solution: Anti-reflective film 1, comprising a substrate 11, a hard coating layer 12 disposed on one side of the substrate 11, and an anti-reflective layer 13 disposed on the side of the hard coating layer 12 opposite to the substrate 11. The thickness of the anti-reflective layer 13 is 0.15 μm or more and 1 μm or less.

Description

Anti-reflective film

This invention relates to an anti-reflective film that provides anti-reflective properties when used in displays and the like.

In displays such as LCDs and OLEDs, light enters the screen from the outside. This light can be reflected, making the displayed image difficult to read. Especially in recent years, with the increasing size of displays, solving this problem has become an increasingly important issue. To address this problem, various anti-reflective and anti-glare treatments are currently implemented in various displays. One such method is the use of anti-reflective films in various displays.

For example, Patent 1 discloses an antireflective film having a laminated structure comprising a substrate, an antireflective layer having defined properties, and a hard coating layer located between them. [Prior Art Documents] [Patent Documents]

[Patent Document 1] Japanese Patent Application Publication No. 2020-008877

[The problem the invention aims to solve]

However, conventional antireflective films, such as those in Patent 1, have the problem that if the surface of the antireflective film is rubbed, the antireflective layer will be damaged and the antireflective performance will be reduced.

In view of the above-mentioned situation, the present invention aims to provide an anti-reflective film with excellent scratch resistance and minimal degradation of anti-reflective properties. [Method for solving the problem]

To achieve the above objectives, firstly, the present invention provides an anti-reflective film, which is an anti-reflective film having a substrate, a hard coating layer disposed on one side of the substrate, and an anti-reflective layer disposed on the side of the hard coating layer opposite to the substrate, characterized in that the thickness of the anti-reflective layer is 0.15 μm or more and 1.00 μm or less (Invention 1).

In the aforementioned invention (Invention 1), the anti-reflective properties are well achieved by using an anti-reflective layer with a thickness within the aforementioned range. Furthermore, the anti-reflective layer of this thickness is not easily scratched even when the surface is rubbed, exhibiting excellent scratch resistance and preventing a decrease in anti-reflective performance due to abrasion. In other words, the anti-reflective film according to the aforementioned invention (Invention 1) achieves a good balance between scratch resistance and anti-reflective performance, resulting in excellent scratch resistance and good anti-reflective performance that is not easily diminished.

In the above invention (Invention 1), the pencil hardness of the surface of the anti-reflective layer in the anti-reflective film is preferably F or higher (Invention 2).

In the above inventions (Inventions 1 and 2), the coefficient of dynamic friction of the surface of the antireflective layer side of the antireflective film is preferably 0.4 or less (Invention 3).

In the above inventions (Inventions 1 to 3), the reflectivity of the surface of the antireflective layer in the antireflective film is preferably below 4% (Invention 4).

In the above inventions (Inventions 1-4), it is preferable that the aforementioned hard coating layer and the aforementioned anti-reflective layer are used to form a material that hardens the composition containing the active energy line hardening component (Invention 5).

In the above inventions (Inventions 1-5), the anti-reflective layer is formed as a single layer, and preferably, the refractive index of the anti-reflective layer is lower than that of the hard coating layer (Invention 6). [Effects of the Invention]

The anti-reflective film of this invention has excellent scratch resistance and its anti-reflective performance is not easily reduced.

The following describes an embodiment of the present invention. Figure 1 is a cross-sectional view of an antireflective film 1 according to an embodiment of the present invention. As shown in Figure 1, the antireflective film 1 according to the present invention includes a substrate 11, a hard coating layer 12 disposed on one side of the substrate 11, and an antireflective layer 13 disposed in the hard coating layer 12 on the opposite side to the substrate 11.

In the antireflective film 1 of this embodiment, the thickness of the antireflective layer 13 is 0.15 μm or more. Therefore, even if the surface of the antireflective layer 13 is rubbed, it is difficult to be scratched, exhibiting excellent scratch resistance and minimal reduction in antireflective performance due to abrasion. Furthermore, the thickness of the antireflective layer 13 is 1.00 μm or less. This maintains good antireflective performance. In other words, in the antireflective film 1 of this embodiment, by ensuring the thickness of the antireflective layer 13 is within the aforementioned range, a good balance between scratch resistance and antireflective performance is achieved, resulting in excellent scratch resistance and minimal reduction in good antireflective performance.

From the viewpoint of scratch resistance, the thickness of the anti-reflective layer 13 is preferably 0.18 μm or more, especially 0.24 μm or more, and even more than 0.30 μm.

Furthermore, from the perspective of anti-reflective performance, the thickness of the anti-reflective layer 13 is preferably below 0.90 μm, especially below 0.70 μm, and further below 0.40 μm.

1. Components 1-1. Anti-reflective layer The anti-reflective layer 13 is formed as a single layer, preferably having a refractive index lower than that of the hard coating layer 12. This allows the anti-reflective film 1 to exhibit excellent anti-reflective properties due to interference of reflected light generated by the refractive index difference with the hard coating layer 12. Consequently, in displays using the anti-reflective film 1, the reflection of external light is reduced, improving the visibility of the displayed image. However, the anti-reflective layer 13 can also be a single anti-reflective layer. In this case, for example, the anti-reflective layer 13 can also have a multi-layered structure.

The antireflective layer 13 of this embodiment is preferably formed of an antireflective layer composition containing binder resin, and further including low-refractive-index particles and additives as needed, but is not limited thereto. For example, it may also be formed of an antireflective layer composition containing low-refractive-index binder resin without containing low-refractive-index particles.

(1) Components (1-1) Adhesive Resin As an adhesive resin, commonly known light-transmitting resins can be used. Examples of such resins include, for example, polyolefin resins, acrylic resins, polyester resins, styrene resins, ABS resins, vinyl chloride resins, fluorinated resins, polysiloxane resins, polycarbonate resins, ethyl polyurethane resins, ethyl polyurethane resins, phenolic resins, urea resins, melamine resins, unsaturated polyester resins, epoxy resins, ethyl polyurethane resins, polystyrene, polyvinyl alcohol, polyvinyl chloride, etc. One of these can be used alone, or two or more can be used in combination.

As a binder resin, a curing component is preferred. A curing component is one that is cured by a trigger such as active energy lines or heat; examples include active energy line curing components and thermosetting components. In this embodiment, from the viewpoint of the hardness and scratch resistance of the formed antireflective layer 13, it is preferable to use an active energy line curing component.

As specific active energy line curing components, examples include polyfunctional (meth)acrylate monomers, (meth)acrylate prepolymers, and other active energy line curing polymers, with polyfunctional (meth)acrylate monomers or (meth)acrylate prepolymers being preferred. Polyfunctional (meth)acrylate monomers and (meth)acrylate prepolymers can be used individually or in combination. Furthermore, in this specification, (meth)acrylate refers to both acrylate and methacrylate. Other similar terms are also used in the same way.

As multifunctional (meth)acrylate monomers, examples include, for instance, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxytrimethylacetic acid neopentyl glycol di(meth)acrylate, dicyclopentyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate phosphate, di(acryloxyethyl)triisocyanate, allylated di(meth)acrylate cyclohexyl ester, ethoxylated bisphenol A diacrylate, and 9,9-bis[4-(2-acryloxyethoxy)phenyl]furan, which are difunctional; trifunctional The following are trifunctional types of hydroxymethylpropane tri(meth)acrylate, dinepentylenetetroxide tri(meth)acrylate, propionic acid-modified dinepentylenetetroxide tri(meth)acrylate, neopentylenetetroxide tri(meth)acrylate, propylene oxide-modified trihydroxymethylpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanate, and ε-caprolactone-modified tris(2-(meth)acryloxyethyl)isocyanate; quadrifunctional types of diglycerol tetra(meth)acrylate and neopentylenetetroxide tetra(meth)acrylate; pentafunctional types of propionic acid-modified dinepentylenetetroxide penta(meth)acrylate; and hexafunctional types of dinepentylenetetroxide hexa(meth)acrylate and caprolactone-modified dinepentylenetetroxide hexa(meth)acrylate. Each of these can be used alone or in combination of two or more. From the perspective of the hardness of the formed antireflective layer 13, it is preferable to have 3 or more functions, and especially 4 or more functions.

On the other hand, examples of (meth)acrylate prepolymers include, for example, polyester acrylate prepolymers, epoxy acrylate prepolymers, ethyl carbamate acrylate prepolymers, and polyol acrylate prepolymers.

As a polyester acrylate prepolymer, for example, it can be obtained by esterifying the hydroxyl groups of a polyester oligomer with hydroxyl groups at both ends obtained by condensing a polycarboxylic acid and a polyol, or by esterifying the terminal hydroxyl groups of an oligomer obtained by esterification with (meth)acrylic acid, or by esterifying the terminal hydroxyl groups of an oligomer obtained by adding a polycarboxylic acid to an alkylene oxide with (meth)acrylic acid.

Epoxy acrylate prepolymers can be obtained, for example, by reacting the oxirane ring of a relatively low molecular weight bisphenol epoxy resin or phenolic epoxy resin with (meth)acrylic acid and then esterifying it.

Ethyl carbamate acrylate prepolymers can be obtained by esterifying polyurethane oligomers, for example, by reacting polyether polyols, polyester polyols, etc., with polyisocyanates, with (meth)acrylic acid.

Polyol acrylate prepolymers can be obtained, for example, by esterifying the hydroxyl groups of polyether polyols with (meth)acrylic acid.

The above prepolymers can be used alone or in combination of two or more.

Here, if a low refractive index resin is used as the binder resin, then the low refractive index particles described later are not necessary. Examples of low refractive index binder resins include, for example, active energy line curing fluorinated resins. Examples of active energy line curing fluorinated resins include fluorinated resins having both fluorinated monomer-derived constituent units and crosslinking monomer-derived constituent units. Specific examples of fluorinated monomer units include, for example, fluoroolefins such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, and perfluoro-2,2-dimethyl-1,3-dioxole; fluorinated alkyl ester derivatives of (meth)acrylic acid; and fluorinated vinyl ethers. As crosslinking monomers, examples of (meth)acrylate monomers besides (meth)acrylate monomers include those with carboxyl, hydroxyl, amino, sulfonic acid, etc.

(1-2) Low-Refractive-Index Particles The antireflective layer composition of this embodiment preferably contains low-refractive-index particles. By containing low-refractive-index particles, the refractive index of the antireflective layer 13 can be effectively reduced, resulting in superior antireflective performance.

As for the aforementioned low refractive index particles, hollow silica microparticles and porous silica microparticles are preferred, with hollow silica microparticles being the most desirable. Hollow silica microparticles can also be modified with organic materials to improve dispersibility. Furthermore, hollow silica microparticles are preferably in the form of an organic sol (colloidal) (hollow silica gel).

Hollow silica microparticles are microscopic structures with open or closed voids within them. Because these voids are filled with gas (air), hollow silica microparticles have a relatively low refractive index. Therefore, by using these microparticles, the refractive index of the antireflective layer 13 can be effectively reduced without compromising its transparency. Hollow silica microparticles can be composed of individual bubbles, continuous bubbles, or both.

The refractive index of the low-refractive-index particles is preferably below 1.45, more preferably below 1.40, especially below 1.35, and further preferably below 1.30. This increases the refractive index difference between the anti-reflective layer 13 and the hard coating layer 12, resulting in superior anti-reflective performance. The lower limit of the refractive index of the low-refractive-index particles is not particularly limited, but it is generally preferred to be above 1.00, especially above 1.10, and further preferably above 1.15. Furthermore, the refractive index of the low-refractive-index particles in this specification is a value determined using the minimum deflection method.

From the perspective of maximizing the benefits of low refractive index, the average particle size of low-refractive-index particles is preferably 5 nm or larger, especially 10 nm or larger, further preferably 30 nm or larger, and ideally 50 nm or larger. Furthermore, from the perspective of minimizing light scattering and achieving excellent transparency, the average particle size of low-refractive-index particles is preferably below 300 nm, especially below 200 nm, and further preferably below 100 nm. Also, the average particle size of low-refractive-index particles in this specification is a value measured using the centrifugal precipitation transmission method.

When the antireflective layer composition of this embodiment contains low-refractive-index particles, the content of these low-refractive-index particles is preferably 1 part by mass or more, more than 10 parts by mass, and particularly more than 30 parts by mass, relative to 100 parts by mass of the binder resin, from the viewpoint of utilizing the low refractive index. Furthermore, from the viewpoint of the coatability and light transmittance of the obtained antireflective layer 13, the content of the aforementioned low-refractive-index particles is preferably 300 parts by mass or less, more than 100 parts by mass, and particularly more than 70 parts by mass, relative to 100 parts by mass of the binder resin.

(1-3) Other Components In addition to the components mentioned above, the antireflective layer composition in this embodiment may also contain various additives. Examples of such additives include, for instance, photopolymerization initiators, surface conditioners, leveling agents, stain inhibitors, dispersants, UV absorbers, antioxidants, light stabilizers, antistatic agents, silane coupling agents, anti-aging agents, thermal polymerization inhibitors, colorants, refractive index adjusters, surfactants, preservation stabilizers, plasticizers, lubricants, defoamers, organic fillers, wettability modifiers, and coating modifiers.

Antireflective layer compositions containing active energy line curing components are preferred when using ultraviolet light as the active energy line, especially those containing photopolymerization initiators. Examples of photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one, 4-(2... (Hydroethoxy)phenyl-2-(hydroxy-2-propyl)one, diphenylone, p-phenyl diphenylone, 4,4'-diethylamino diphenylone, dichloro diphenylone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methyl-thioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketone, acetophenone dimethyl ketone, p-dimethylaminobenzoate, etc. These can be used alone or in combination of two or more.

The content of the photopolymerization initiator in the antireflective layer composition is preferably 0.01 parts by weight or more, particularly 0.1 parts by weight or more, and further preferably 1 part by weight or more, relative to 100 parts by weight of the active energy line curing component. Furthermore, the upper limit is preferably 20 parts by weight or less, particularly 15 parts by weight or less, and further preferably 10 parts by weight or less.

From the viewpoint of reducing the coefficient of dynamic friction of the surface of the antireflective layer 13 (the surface of the antireflective film 1) and improving scratch resistance, the composition of the antireflective layer in this embodiment is preferably containing a surface modifier. Examples of surface modifiers include, for example, polysiloxane-based surface modifiers, fluorine-based surface modifiers, and acrylic-based surface modifiers. From the viewpoint that the coefficient of dynamic friction of the surface of the antireflective film 1 is easily within the preferred range described later, the use of a polysiloxane-based surface modifier or a fluorine-based surface modifier is preferred in this embodiment. More specifically, examples include polysiloxane oligomers (including reactive ones), polysiloxane oils (including modified ones), and fluorine-based oligomers (including reactive ones). It is preferable to use reactive fluorinated oligomers or reactive polysiloxane oligomers, especially fluorinated oligomers or polysiloxane oligomers with (meth)acrylic acid groups having reactive energy lines.

The content of the surface modifier in the antireflective layer composition is preferably 1 part by weight or more, particularly 3 parts by weight or more, and further preferably 5 parts by weight or more, relative to 100 parts by weight of the binder resin. Furthermore, the content of the aforementioned surface modifier is preferably 30 parts by weight or less, particularly 20 parts by weight or less, and further preferably 10 parts by weight or less, relative to 100 parts by weight of the binder resin.

(2) Properties of the Anti-reflective Layer The refractive index of the anti-reflective layer 13 is preferably below 1.48, more preferably below 1.46, particularly below 1.45, and further preferably below 1.44. This allows the refractive index of the anti-reflective layer 13 to be lower than that of the hard coating layer 12, resulting in superior anti-reflective performance of the anti-reflective film 1. The lower limit of the aforementioned refractive index is not particularly limited, but is generally preferred to be above 1.30, and particularly above 1.35. Furthermore, the refractive index of the anti-reflective layer in this specification is determined using an elliptic polarimeter.

1-2. Hard Coating The hard coating 12 in the antireflective film 1 is preferably formed of a hard coating composition containing a binder resin, and further containing, as needed, microparticles, additives, etc.

(1) Components (1-1) Binder Resin As the binder resin, the aforementioned components included in the antireflective layer composition used to form the antireflective layer 13 can be used. From the viewpoint of obtaining a hard coating layer 12 with excellent scratch resistance while increasing the refractive index difference with the antireflective layer 13, the binder resin preferably has a refractive index of 1.46~1.75, more preferably 1.48~1.65, and particularly preferably 1.49~1.54.

(1-2) Microparticles The hard coating composition in this embodiment may be free of microparticles, but may also contain microparticles to obtain the desired physical properties. For example, from the viewpoint of imparting glare suppression and anti-glare properties to the hard coating 12, it may also contain light-diffusing microparticles (light-diffusing microparticles).

Examples of light-diffusing microparticles include inorganic microparticles such as silicon dioxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide; organic light-transmitting microparticles such as acrylic resins like polymethyl methacrylate, polystyrene resins, polymethyl methacrylate-polystyrene copolymers, polyethylene resins, and epoxy resins; and microparticles formed from silica-containing compounds with an intermediate structure between inorganic and organic elements, such as polysiloxane resins (e.g., the Tospearl series manufactured by Momentive Performance Materials Japan). Each of these light-diffusing microparticles can be used alone or in combination of two or more.

The shape of the light-diffusing particles can be a uniform sphere, especially a true sphere, or a random amorphous shape. The average particle size of the light-diffusing particles obtained by laser diffraction is preferably 0.1 μm or more, especially 1 μm or more, and further preferably 2 μm or more. Furthermore, the aforementioned average particle size is preferably 20 μm or less, more preferably 10 μm or less, especially 5 μm or less, and further preferably 3 μm or less. An average particle size within the above range makes it easier to balance the desired haze performance and anti-reflective properties.

The refractive index of the light-diffusing particles is preferably 1.40~1.80, more preferably 1.42~1.60, and preferably 1.43~1.48. This facilitates a balance between anti-reflective and anti-glare properties. Furthermore, the refractive index of the light-diffusing particles in this specification is the value obtained as measured below. The particles to be measured are placed on a glass slide, a refractive index standard solution is dropped onto the particles, and a coverslip is placed on top to prepare a sample. The sample is observed under a microscope according to Method B of JIS K7142:2014. The refractive index of the standard solution from which the particle outline is least clearly visible is taken as the refractive index of that particle.

Regarding the particle size distribution of spherical light-diffusing particles, from the viewpoint of uniform light diffusion, the coefficient of variation (CV) of the particle size shown in the following formula (1) is preferably 3% or more, particularly 5% or more, and even more than 10%. Furthermore, the aforementioned CV value is preferably 50% or less, more preferably 40% or less, and especially preferably 30% or less. Coefficient of variation (CV) of particle size = (Standard deviation particle size / Average particle size) × 100 … (1)

On the other hand, regarding the particle size distribution of amorphous light-diffusing particles, from the viewpoint of random light diffusion, a particle size variation coefficient (CV value) of 50% or more is preferred, especially 60% or more, and further preferably 70% or more. Furthermore, the aforementioned CV value is preferably 200% or less, more preferably 175% or less, especially 150% or less, and further preferably 125% or less.

Furthermore, the average particle size of the light-diffusing particles in this instruction manual is determined by centrifugal precipitation transmission method. The determination of the average particle size by centrifugal precipitation transmission method in this instruction manual is performed using a centrifugal automatic particle size distribution measuring device (Horiba Seisakusho, CAPA-700) with 1.2g of particles thoroughly mixed with 98.8g of isopropanol as the sample. Moreover, the coefficient of variation (CV) of the particle size of the light-diffusing particles in this instruction manual is a value obtained by dynamic light scattering method.

The content of light-diffusing microparticles in the hard coating composition is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, and especially preferably 5 parts by weight or more, relative to 100 parts by weight of binder resin. This makes it easier to obtain the desired light diffusion properties. Furthermore, from the viewpoint of coatability and film strength, the content of light-diffusing microparticles is preferably 100 parts by weight or less, more preferably 50 parts by weight or less, and especially preferably 20 parts by weight or less, relative to 100 parts by weight of binder resin.

When imparting anti-glare properties to the hard coating layer 12, it is preferable that the hard coating composition contains more nanoparticles. This allows the aforementioned light-diffusing particles to easily segregate to the surface of the anti-reflective layer 13 side of the hard coating layer 12 (hereinafter referred to as the "surface of the hard coating layer 12"). As a result, it is easy to form an uneven surface on the hard coating layer 12, further enhancing the anti-glare effect.

As an example of nanoparticles, silicon dioxide nanoparticles are preferred. Silicon dioxide nanoparticles can be in the form of colloids or have reactive groups on their surface. Examples of reactive groups include (meth)acrylic acid groups.

The refractive index of nanoparticles is preferably 1.40~1.80, even better 1.42~1.60, and exceptionally good 1.44~1.48.

The average particle size of the nanoparticles is preferably 1 nm or larger, more preferably 10 nm or larger, and especially preferably 20 nm or larger. Furthermore, the average particle size is preferably 1000 nm or smaller, more preferably 500 nm or smaller, and especially preferably 90 nm or smaller. Within the above-mentioned average particle size range, the light-diffusing particles can easily segregate to the surface of the hard coating layer 12. Also, the average particle size of the nanoparticles is a value determined by the zeta potential method.

The content of nanoparticles in the hard coating composition is preferably 1 part by weight or more, more preferably 10 parts by weight or more, and especially preferably 100 parts by weight or more, relative to 100 parts by weight of binder resin. This allows the light-diffusing particles to easily segregate to the surface of the hard coating layer 12. Furthermore, from the viewpoint of coatability and film strength, the content of nanoparticles is preferably 1000 parts by weight or less, more preferably 500 parts by weight or less, and especially preferably 200 parts by weight or less, relative to 100 parts by weight of binder resin.

(1-3) Other Components In addition to the components described above, the hard coating composition in this embodiment may also contain various additives. As various additives, the aforementioned components contained in the antireflective layer composition used to form the antireflective layer 13 can be used.

For example, hard coating compositions contain active energy line curing components. When using ultraviolet light as the active energy line, it is preferable that the hard coating composition contains a photopolymerization initiator. The type and content of the photopolymerization initiator are the same as those for antireflective coating compositions.

(2) Properties of the Hard Coating Layer The refractive index of the hard coating layer 12 is preferably higher than that of the antireflective layer 13. Specifically, the refractive index of the hard coating layer 12 is preferably 1.46 or higher, particularly 1.48 or higher, and further preferably 1.50 or higher. This increases the refractive index difference between the hard coating layer 12 and the antireflective layer 13, resulting in better antireflective performance of the antireflective film 1. While there is no particular upper limit to the refractive index of the hard coating layer 12, it is generally preferred to be 1.75 or lower, particularly 1.65 or lower, and further preferably 1.58 or lower. Furthermore, the method for measuring the refractive index of the hard coating layer 12 in this specification is as described in the test examples below.

The thickness of the hard coating 12 is preferably 0.5 μm or more, more preferably 1 μm or more, especially 2 μm or more, and further preferably 3 μm or more. This results in superior scratch resistance and anti-reflective properties. Furthermore, the thickness of the hard coating 12 is preferably 30 μm or less, more preferably 15 μm or less, especially 10 μm or less, and further preferably 7 μm or less. This helps to suppress curling caused by hardening shrinkage.

1-3. Substrate While not particularly limited, the substrate 11 preferably uses a resin film with a predetermined transparency. Examples of such resin films include, for instance, polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin films such as polyethylene films and polypropylene films; cellophane; cellulose diacetate films; cellulose triacetate films; cellulose acetate butyrate films; polyvinyl chloride films; polyvinyl chloride films; polyvinyl alcohol films; and ethylene-vinyl acetate copolymers. Resin films or laminates thereof, including polystyrene films, polycarbonate films, polymethylpentene films, polyurethane films, polyetheretherketone films, polyetherurethane films, polyetherimide films, fluororesin films, polyamide films, acrylic resin films, polyurethane resin films, nobornene polymer films, cyclic olefin polymer films, cyclic conjugated diene polymer films, and vinyl cyclohexane polymer films, are preferred. Among these, polyethylene terephthalate films, polycarbonate films, cellulose triacetate films, and nobornene polymer films are preferred in terms of mechanical strength, etc.

Furthermore, in the aforementioned substrate 11, to improve the adhesion between layers disposed on its surface, surface treatments such as primer treatment, oxidation, and texturing can be applied to one or both sides as needed. Examples of oxidation methods include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, and ozone/ultraviolet treatment. Examples of texturing methods include sandblasting and solvent treatment. These surface treatment methods can be appropriately selected depending on the type of substrate 11. Generally, corona discharge treatment is preferred in terms of improving adhesion and operability.

The thickness of the substrate 11 is preferably 10 μm or more, especially 25 μm or more, and further preferably 50 μm or more. Also, the thickness of the substrate 11 is preferably 1000 μm or less, especially 500 μm or less, and further preferably 300 μm or less.

1-4. Other Compositions Regarding the antireflective film 1 of this embodiment, an adhesive layer may also be prepared on the side opposite to the substrate 11 and the hard coating layer 12. There are no particular limitations on the adhesive used to constitute this adhesive layer; known adhesives such as acrylic adhesives, rubber adhesives, and polysiloxane adhesives can be used, but it is preferable to use an adhesive with a predetermined degree of transparency.

Furthermore, when the antireflective film 1 of this embodiment has the aforementioned adhesive layer, a release liner can also be laminated on the side of the antireflective film 1 opposite to the adhesive layer and the substrate 11. There are no particular limitations as long as the release liner has the desired peelability on its peeling surface (the surface in contact with the adhesive layer), and any known release liner that can be used, such as a resin film whose single side has been treated with a release agent, is acceptable.

2. Properties of the Anti-reflective Film (1) Haze Value The upper limit of the haze value of the anti-reflective film 1 in this embodiment is not particularly limited, but from a high-precision perspective, 80% or less is preferred, 40% or less is more preferred, especially 20% or less is preferred, and furthermore, 10% or less is preferred. On the other hand, the lower limit of the haze value of the anti-reflective film 1, when imparting glare suppression and anti-glare properties to the anti-reflective film 1, is preferably 0.1% or more, 0.5% or more is more preferred, and especially 6% or more is preferred. Furthermore, the method for measuring the haze value is as described in the test examples below.

(2) Total Light Transmittance The total light transmittance of the antireflective film 1 in this embodiment is preferably 80% or higher, more preferably 85% or higher, particularly preferably 88% or higher, and further preferably 90% or higher. A total light transmittance of 80% or higher indicates very high transparency, making it particularly suitable for optical applications (displays). Furthermore, the method for measuring total light transmittance is as described in the test examples below.

(3) Pencil Hardness Regarding the antireflective film 1 of this embodiment, the pencil hardness of the surface of the antireflective layer 13 opposite to the hard coating layer 12 (hereinafter referred to as the "surface of the antireflective film 1") is preferably F or higher, particularly H or higher, and further preferably 2H or higher. With this pencil hardness of the antireflective layer 13, the surface of the antireflective film 1 has sufficient hardness and can exhibit excellent scratch resistance. The upper limit of the above-mentioned pencil hardness is not particularly limited, but 9H or lower is preferred. Furthermore, the method for measuring pencil hardness is as described in the test examples below.

(4) Coefficient of Dynamic Friction The coefficient of dynamic friction of the surface of the antireflective film 1 of this embodiment is preferably 0.4 or less, more preferably 0.3 or less, particularly preferably 0.25 or less, and further preferably 0.2 or less. This provides better scratch resistance. From the viewpoint of operability and preventing blocking, the lower limit of the above-mentioned coefficient of dynamic friction is preferably 0.001 or more, more preferably 0.01 or more, particularly preferably 0.05 or more, and further preferably 0.10 or more. Furthermore, the method for measuring the coefficient of dynamic friction is as described in the test examples below.

(5) Reflectivity The reflectivity of the surface of the antireflective film 1 in this embodiment is preferably 4% or less, more preferably 3.5% or less, particularly preferably 3% or less, and further preferably 2.5% or less. Therefore, the display panel using this antireflective film 1 can reduce the reflection of external light, improving the visibility of the image. Furthermore, the lower limit of the above-mentioned reflectivity is not particularly limited, but approximately 1.4% or more is preferred. Also, the method for measuring reflectivity in this specification is as shown in the test examples described later.

(6) The difference in reflectance before and after the abrasion resistance test: On the surface of the antireflective film 1, the reflectance (%) measured after 10 repeated wipings with #0000 steel wool under a load of 250 g/ ^cm² is the difference between the reflectance (%) before and after the abrasion resistance test and the reflectance after the abrasion resistance test. The difference in reflectance is preferably less than 1.3 percentage points, more preferably less than 1.0 percentage points, especially less than 0.5 percentage points, and further preferably less than 0.3 percentage points. In this way, the antireflective film 1 can maintain its antireflective performance even when the surface is rubbed.

(7) Abrasion resistance Regarding the surface of the anti-reflective film 1 (2cm×2cm), when using #0000 steel wool to rub it repeatedly 10 times with a load of 250g/cm ² , the number of scratches on the surface is preferably less than 5, better than 3, especially better than 1, and best of 0.

3. Manufacturing Method of Anti-reflective Film The manufacturing method of anti-reflective film 1 is not particularly limited. For example, it is preferable to form an anti-reflective layer 13 on the side of the hard coating layer 12 opposite to the substrate 11 after forming a hard coating layer 12 on one side of the substrate 11. For example, the aforementioned hard coating layer can be applied to the substrate 11 with a coating liquid of the composition to form a hardened hard coating layer 12. After forming the hard coating layer 12 on the substrate 11, an anti-reflective layer coating liquid of the composition is applied to the side of the hard coating layer 12 opposite to the substrate 11, for example, and then hardened to form the anti-reflective layer 13. The coating solutions for the above-mentioned hard coating and antireflective layer compositions may also contain solvents as desired.

Solvents used for formulating hard coatings can be used for improving coatability, adjusting viscosity, adjusting solid content, etc., and can be used without special limitations as long as they can dissolve binders, resins, etc.

Specific examples of solvents include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl lactate, and γ-butyrolactone; ethers such as ethylene glycol monomethyl ether (methyl cyrrolidone), ethylene glycol monoethyl ether (ethyl cyrrolidone), diethylene glycol monobutyl ether (butyl cyrrolidone), and propylene glycol monomethyl ether; aromatic hydrocarbons such as benzene, toluene, and xylene; and amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

The application of hard coating compositions can be carried out using conventional methods, such as rod coating, knife coating, Mayer bar coating, roller coating, scraper coating, stencil coating, and gravure coating. After applying the hard coating composition, it is best to dry the coating at a temperature of 40°C to 120°C for approximately 30 seconds to 5 minutes.

The curing of the coating can be carried out depending on the type of binder resin used, for example, by heat treatment or irradiation with active energy lines. In particular, when using the aforementioned multifunctional (meth)acrylate monomers or (meth)acrylate-based prepolymers as binder resins, it is preferable to cure the hard coating composition by irradiating the coating film of the hard coating composition with active energy lines such as ultraviolet rays or electron beams in an air environment. Curing it in an air environment can improve the adhesion to the antireflective layer 13. Ultraviolet irradiation can be performed using high-pressure mercury lamps, fusion H lamps, xenon lamps, etc., with an irradiance of 50 mW/ ^cm² or higher and 1000 mW/ ^cm² or lower, and a light intensity of 50 mJ/ ^cm² or higher and 1000 mJ/ ^cm² or lower. On the other hand, electron beam irradiation can be performed using electron beam accelerators, etc., with an electron beam irradiation dose of 10 klad or higher and 1000 klad or lower.

The solvent used for preparing the antireflective layer composition can be the same as that used for preparing the hard coating composition. Furthermore, the coating method for the antireflective layer composition and the curing method for the formed coating film can be performed using the same methods as those for the coating and curing methods for the hard coating composition. However, it is preferable to perform the curing of the antireflective layer composition under a nitrogen atmosphere. This results in better scratch resistance of the antireflective layer 13.

4. Use of the anti-reflective film The anti-reflective film 1 of this embodiment can be used as, for example, the surface layer or internal intermediate layer of various displays such as liquid crystal displays, organic EL displays, and touch panels.

The embodiments described above are provided for ease of understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to include all design variations and equivalents that fall within the scope of the present invention.

For example, other layers may exist between the substrate 11 and the hard coating layer 12, or between the hard coating layer 12 and the antireflective layer 13, in the antireflective film 1. Furthermore, other layers may also be formed on the side of the antireflective layer 13 opposite to the hard coating layer 12. [Example]

The invention will be further illustrated below by examples, but the scope of the invention is not limited to these examples.

[Formulation Example 1] Hard Coating Compound (HC-1)

100 parts by weight of neopentyl terephthalate tetraacrylate (A) as a binder resin (solid content conversion, the same below), and 3 parts by weight of 1-hydroxycyclohexylphenyl ketone (F) as a photopolymerization initiator, were mixed and diluted with propylene glycol monoethyl ether (PGM) as a solvent to obtain a coating solution for hard coating (HC-1).

[Formulation Example 2] Hard Coating Compound (HC-2)

100 parts by weight of neopentyl terephthalate tetraacrylate (A) as a binder resin, 10 parts by weight of silica microparticles (B; material: silica, shape: amorphous, refractive index: 1.46, average particle size: 1.5 μm, particle size variation coefficient: 83%) as light-diffusing microparticles, and 3 parts by weight of 1-hydroxycyclohexylphenyl ketone (F) as a photopolymerization initiator were mixed and diluted with propylene glycol monoethyl ether (PGM) as a solvent to obtain a coating solution for hard coating (HC-2).

[Formulation Example 3] Hard Coating Compound (HC-3)

100 parts by weight of neopentyl terephthalate tetraacrylate (A) as a binder resin, 150 parts by weight of silica nanoparticles (C; average particle size: 40 nm, refractive index: 1.46) as nanoparticles, 10 parts by weight of polysiloxane microparticles (D; shape: spherical, refractive index: 1.43, average particle size: 3 μm, particle size variation coefficient: 19%) as light-diffusing microparticles, and 3 parts by weight of 1-hydroxycyclohexylphenyl ketone (F) as a photopolymerization initiator were mixed and diluted with propylene glycol monoethyl ether (PGM) as a solvent to obtain a coating solution for hard coating (HC-3).

[Preparation Example 4] Antireflective Layer Composition (LR-1)

A coating solution for an antireflective layer was prepared by mixing and diluting 100 parts by mass of neopentyl terephthalate tetraacrylate (A) as a binder resin, 50 parts by mass of hollow silica microparticles (E; average particle size: 60 nm, refractive index 1.25) as low refractive index particles, 5 parts by mass of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane-1-one (G) as a photopolymerization initiator, and 7.5 parts by mass of reactive polysiloxane oligomer (H; manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "UV-AF100") as a surface conditioner, using a 1:2 (volume ratio) mixed solvent of methyl isobutyl ketone (MIBK) and propylene glycol monoethyl ether (PGM).

[Formulation Example 5] Antireflective Layer Composition (LR-2)

An active energy line-curing fluorinated resin compound (I; manufactured by NEOS, product name "SAMPLE C") was diluted with a 1:2 (volume ratio) mixture of methyl isobutyl ketone (MIBK) and propylene glycol monoethyl ether (PGM) to obtain an antireflective coating (LR-2).

The composition of preparation examples 1-5 is shown in Table 1. Furthermore, details of the abbreviations, etc., recorded in Table 1 are as follows.

A: Neopentyl tetraacrylate

B: Silica microparticles (Material: Silica, Shape: Irregular, Average particle size: 1.5 μm, Coefficient of variation in particle size: 83%, Refractive index: 1.46)

C: Silicon dioxide nanoparticles (average particle size 40 nm, refractive index: 1.46)

D: Polysilicon microparticles (Material: Polysilicon, Shape: Spherical, Average particle size: 3μm, Particle size variation coefficient: 19%, Refractive index: 1.43)

E: Hollow silica microparticles (average particle size 60 nm, refractive index: 1.25)

F: 1-Hydrocyclohexylphenyl ketone

G: 2-Methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane-1-one

H: Reactive polysiloxane oligomer (manufactured by Japan Synthetic Chemical Industry Co., Ltd., product name "UV-AF100")

I: Active energy line-curing fluorinated resin composition (manufactured by NEOS Corporation, product name "SAMPLE C", contains photopolymerization initiator and surface conditioner)

[Implementation Example 1]

On one side of a PET film (manufactured by Toray Industries, product name "Lumirror U48", thickness 125 μm) used as the substrate, a coating solution of the hard coating compound (HC-1) obtained in Example 1 was prepared using a Mayer rod and allowed to dry. Then, the coating was irradiated with ultraviolet light in an air environment to form a hard coating layer with a thickness of 5 μm.

Next, a coating solution of the antireflective layer composition (LR-1) obtained in Example 4 was applied to the surface of the aforementioned hard coating layer using a Mayer rod and allowed to dry. Then, the coating was irradiated with ultraviolet light under a nitrogen atmosphere to form an antireflective layer with a thickness of 0.30 μm. This resulted in an antireflective film consisting of a substrate, a hard coating layer, and an antireflective layer sequentially deposited.

[Examples 2-5, Comparative Examples 1-2, Reference Examples] Except for changing the type and thickness of the hard coating composition and the type and thickness of the antireflective layer composition as shown in Table 2, the antireflective film is manufactured in the same manner as in Example 1.

[Experimental Example 1] (Determination of Refractive Index) Prepare a mixture (HC-2’) from HC-2 to which silica particles (B) are removed, and a mixture (HC-3’) from HC-3 to which polysiloxane particles (D) are removed, from the hard coating compositions (HC-2, HC-3) prepared in each of the preparation examples. Apply the coating solutions of the hard coating compositions (HC-1, HC-2’, HC-3’) and the antireflective layer compositions (LR-1, LR-2) to the side of a polyethylene terephthalate film (manufactured by Toyosho Co., Ltd., product name "cosmoshine A4100", thickness: 50 μm) having an easy-adhesion layer on one side, in the same manner as in Example 1, and allow it to harden to form a layer with a thickness of 100 nm. Sand the surface of the bonding layer with sandpaper, then apply black ink (ZEBRA product name "Mackee Black") using a pen.

The refractive indices of each layer were measured using a spectroscopic elliptic polarimeter (J.A. WOOLLAM, product name "M-2000") under conditions of a wavelength of 589 nm and a temperature of 23 °C. The results are shown in Table 1. Furthermore, the refractive indices of silica microparticles (B) and polysiloxane microparticles (D), along with their respective mixing ratios, were added to calculate the refractive index of the hard coating layer. The value, rounded to two decimal places, is the same as the refractive index in Table 1.

[Experimental Example 2] (Determination of Fog Value) The antireflective films manufactured in the Embodiments, Comparative Examples, and Reference Examples had their fog values (%) measured using a fog meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name "NDH5000") according to JIS K7136:2000. The results are shown in Table 2.

[Experimental Example 3] (Determination of Total Light Transmittance) The antireflective films manufactured in the Embodiments, Comparative Examples, and Reference Examples had their total light transmittance (%) measured using a haze meter (manufactured by Nippon Denshoku Kogyo, product name "NDH5000") according to JIS K7361-1:1997. The results are shown in Table 2.

[Experiment Example 4] (Determination of Pencil Hardness) The antireflective films prepared in the Examples, Comparative Examples, and Reference Examples were tested for pencil hardness using an electric pencil scratch hardness tester (manufactured by Yasuda Seiki Co., Ltd., product name "No. 553-M1") according to JIS K5600. The results are shown in Table 2.

[Experimental Example 5] (Determination of Coefficient of Kinetic Friction) The coefficient of kinetic friction was determined on the surface of the antireflective layer of the antireflective film prepared in the Examples, Comparative Examples, and Reference Examples using #0000 steel wool, with a load of 250 g/ ^cm² and a speed of 50 mm/s. The determination was performed using a static friction measuring machine (Trinity-lab, product name "TRILAB master TL201Ts"). The results are shown in Table 2.

[Experimental Example 6] (Determination of Reflectivity/Evaluation of Antireflective Performance Before Abrasion Resistance Test) The substrate side of the antireflective films prepared in the Examples, Comparative Examples, and Reference Examples was adhered to one side of a black acrylic sheet (Mitsubishi Rayon Co., Ltd., product name "OPTERIA MO-3006C", refractive index 1.49, haze value: <1.0%) using an acrylic transparent adhesive. Then, the surface of the antireflective layer of the antireflective film was measured using a UV-Vis-NIR spectrophotometer (Shimadzu Corporation, product name "UV-3600"). The lowest reflectivity in the visible light region (360~830nm) was taken as the reflectivity (%). The results are shown in Table 2.

Furthermore, the antireflective properties before the scratch resistance test were evaluated according to the following criteria. The results are shown in Table 2. 3: Reflectivity below 2.5%, excellent antireflective performance 2: Reflectivity above 2.5% but below 3.5%, relatively good antireflective performance 1: Reflectivity above 3.5%, poor antireflective performance

[Experimental Example 7] (Evaluation of the Change in Antireflective Performance Before and After the Abrasion Resistance Test) The surface (2cm × 2cm) of the antireflective layer of the antireflective film prepared in the Examples, Comparative Examples, and Reference Examples was repeatedly rubbed 10 times with #0000 steel wool under a load of 250g/ ^cm² . Then, the reflectivity (%; and the reflectivity after the abrasion resistance test) was measured using the same method as in Experimental Example 6. The difference in reflectivity (percentage points) between the reflectivity after the abrasion resistance test and the reflectivity before the abrasion resistance test was used to evaluate the change in antireflective performance before and after the abrasion resistance test according to the following criteria. The results are shown in Table 2. 3: Reflectivity difference less than 0.5 percentage points, small change in anti-reflection performance; 2: Reflectivity difference greater than 0.5 percentage points but less than 1.3 percentage points, relatively small change in anti-reflection performance; 1: Reflectivity difference greater than 1.3 percentage points, large change in anti-reflection performance.

Furthermore, the number of scratches added to the surface of any anti-reflective film after the above-mentioned scratch resistance test is 0.

[Table 1] Bonding resin particle Low refractive index particles Photopolymerization initiator Surface Conditioner Refractive index Kind mass Kind mass Kind mass Kind mass Kind mass Modulation example 1 Hard coating composition HC-1 A 100 - - - - F 3 - - 1.50 Modulation example 2 HC-2 A 100 B 10 - - F 3 - - 1.50 Modulation example 3 HC-3 A 100 C 150 - - F 3 - - 1.49 D 10 Modulation example 4 Anti-reflective layer components LR-1 A 100 - - E 50 G 5 H 7.5 1.43 Modulation example 5 LR-2 I 100 - - - - - - - - 1.43

[Table 2] Hard coating Anti-reflective layer Fog level (%) Total light transmittance (%) Pencil hardness Coefficient of kinetic friction reflectivity Anti-reflective properties before scratch resistance test Changes in antireflective properties before and after abrasion resistance test Kind Thickness (μm) Kind Thickness (μm) Before abrasion resistance test (%) Abrasion resistance test results (%) Difference in reflectivity (percentage points) Implementation Example 1 HC-1 5 LR-1 0.30 0.9 92.8 3H 0.18 2.3 2.7 0.4 3 3 Implementation Example 2 HC-1 5 LR-2 0.40 0.9 92.7 3H 0.20 2.2 2.5 0.3 3 3 Implementation Example 3 HC-2 4 LR-1 0.30 8.4 91.9 3H 0.19 2.7 3.3 0.6 2 2 Implementation Example 4 HC-3 4 LR-1 0.20 9.1 92.1 3H 0.18 2.9 3.5 0.6 2 2 Implementation Example 5 HC-1 5 LR-1 0.50 1.1 91.5 3H 0.16 3.2 3.4 0.2 2 3 Comparative example 1 HC-1 5 LR-2 0.10 0.8 93.1 3H 0.21 1.9 3.3 1.4 3 1 Comparative example 2 - - LR-1 0.30 1.2 92.1 HB 0.21 2.0 3.8 1.8 3 1 Reference HC-1 5 - - 0.9 91.1 3H 0.52 4.1 - - 1 -

As shown in Table 2, the anti-reflective film manufactured in the embodiments exhibits excellent scratch resistance and its anti-reflective performance is not easily degraded. [Industrial Applicability]

The anti-reflective film of this invention is preferably used, for example, on the visible side of a cover material attached to various displays.

1: Anti-reflective film 11: Substrate 12: Hard coating 13: Anti-reflective layer

[Figure 1] Cross-sectional view of an antireflective film of an embodiment of the present invention.

1: Anti-reflective coating

11: Substrate

12: Hard Coating

13: Anti-reflective layer

Claims (6)

An antireflective film comprising a substrate, a hard coating disposed on one side of the substrate, and an antireflective layer disposed in the hard coating on the opposite side of the substrate, characterized in that the thickness of the antireflective layer is 0.20 μm or more and 1.00 μm or less (excluding 0.20 μm). The antireflective film as described in claim 1, wherein the pencil hardness of the surface of the antireflective layer in the aforementioned antireflective film is F or higher. The antireflective film as described in claim 1, wherein the coefficient of kinetic friction of the surface on the side of the aforementioned antireflective layer in the aforementioned antireflective film is 0.4 or less. The antireflective film as described in claim 1, wherein the reflectivity of the surface on the side of the aforementioned antireflective layer in the aforementioned antireflective film is 4% or less. The antireflective film as claimed in claim 1, wherein the aforementioned hard coating and the aforementioned antireflective layer are formed of a material that hardens an assembly containing an active energy line hardening component. The antireflective film as described in any one of claims 1 to 5, wherein the aforementioned antireflective layer is formed of a single layer and the refractive index of the aforementioned antireflective layer is lower than the refractive index of the aforementioned hard coating layer.