JP2023096299A - Reflection prevention film - Google Patents

Abstract

To provide a reflection prevention film that has an excellent resistance to abrasion by contribution of a hardcoat layer.SOLUTION: A reflection prevention film 10 includes: a base material film 12; a hardcoat layer 16 on the surface of the base material film 12; and a reflection prevention layer 14 on the surface of the hardcoat layer 16. The hardcoat layer 16 is made of a cured material of an ionization radiation curable composition including a (meth)acrylate compound and a polyfunctional secondary thiol.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an antireflection film, and more particularly to an antireflection film suitable for use on the surface of a display such as a liquid crystal display, an organic EL display, or a touch panel of a smart phone.

2. Description of the Related Art An antireflection film is sometimes placed on the display surface of a liquid crystal display, an organic EL display, a touch panel of a smart phone, or the like, in order to prevent external light from reflecting on the screen.

As an antireflection film, one having a hard coat layer and an antireflection layer (low refractive layer) on a base film in this order is known. For example, in Patent Document 1 filed by the applicant, by studying the composition of the low refractive index layer formed on the surface of the hard coat layer, the antireflection properties, scratch resistance, and antifouling properties of the antireflection film are We are trying to improve.

WO2021/020504

In order to improve the scratch resistance of the antireflection film, it is effective to devise the constituent material of the antireflection layer formed on the surface of the hard coat layer as in the embodiment of Patent Document 1. However, devising the constituent material of the hard coat layer is also considered to be effective in improving the scratch resistance of the antireflection film. In addition to the antireflection layer, if the hard coat layer also increases the scratch resistance, the scratch resistance of the antireflection film as a whole may be more effectively improved.

The problem to be solved by the present invention is to provide an antireflection film having excellent scratch resistance due to the contribution of the hard coat layer.

In order to solve the above problems, the antireflection film according to the present invention comprises a base film, a hard coat layer formed on the surface of the base film, and an antireflection layer formed on the surface of the hard coat layer. and the hard coat layer is composed of a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound and a polyfunctional secondary thiol.

Here, the ionizing radiation-curable composition includes, as the (meth)acrylate compound, a polyfunctional urethane (meth)acrylate compound and a pentaerythritol (meth)acrylate compound having a hydroxyl value of 200 mgKOH/g or more and 350 mgKOH/g or less. , should be included. In this case, the content of the pentaerythritol (meth)acrylate compound in the ionizing radiation-curable composition is preferably 15% by mass or more and 75% by mass or less with respect to 100% by mass of the solid content. Moreover, the said polyfunctional secondary thiol is good in it being more than trifunctional. The content of the polyfunctional secondary thiol in the ionizing radiation-curable composition is preferably 3% by mass or more and 35% by mass or less with respect to 100% by mass of the solid content.

The base film and the antireflection layer are preferably made of a material having a carbon-carbon double bond at least at a portion in contact with the hard coat layer. Moreover, it is preferable that at least the part of the antireflection layer in contact with the hard coat layer is made of a cured product of an ionizing radiation-curable material containing (meth)acrylate.

The antireflection film according to the present invention includes a base film, a hard coat layer formed on the surface of the base film, and an antireflection layer formed on the surface of the hard coat layer. , The hard coat layer is composed of a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound and a polyfunctional secondary thiol, so that the hard coat layer contributes to excellent scratch resistance. It becomes a thing with sex.

Here, the ionizing radiation-curable composition comprises, as (meth)acrylate compounds, a polyfunctional urethane (meth)acrylate compound and a pentaerythritol (meth)acrylate compound having a hydroxyl value of 200 mgKOH/g or more and 350 mgKOH/g or less. When it is contained, the scratch resistance of the antireflection film can be effectively enhanced. Moreover, it is excellent in the effect of suppressing curling while maintaining the hardness of the antireflection film at a high level. In this case, when the content of the pentaerythritol (meth)acrylate compound in the ionizing radiation-curable composition is 15% by mass or more and 75% by mass or less with respect to 100% by mass of the solid content, the above effects are particularly enhanced. .

Moreover, when the polyfunctional secondary thiol is trifunctional or higher, the hardness of the antireflection film can be effectively increased. When the content of the polyfunctional secondary thiol in the ionizing radiation-curable composition is 3% by mass or more and 35% by mass or less with respect to 100% by mass of the solid content, the effect of improving the scratch resistance of the antireflection film is obtained. Hardness can be ensured while obtaining high.

In the substrate film and the antireflection layer, when at least the portion in contact with the hard coat layer is composed of a material having a carbon-carbon double bond, the carbon-carbon divalent contained in the substrate film and the antireflection layer The formation of a chemical bond between the double bond and the polyfunctional secondary thiol contained in the hard coat layer increases the adhesion between the layers. Further, in the antireflection layer, when at least the portion in contact with the hard coat layer is composed of a cured product of an ionizing radiation-curable material containing (meth)acrylate, Adhesion is effectively enhanced.

1 is a cross-sectional view of an antireflection film according to a first embodiment of the present invention; FIG. FIG. 2 is a cross-sectional view of an antireflection film according to a second embodiment of the invention; FIG. 4 is a cross-sectional view of an antireflection film according to a third embodiment of the invention; FIG. 4 is a cross-sectional view of an antireflection film according to a fourth embodiment of the invention;

The present invention will be described in detail below.

<Antireflection film of the first embodiment>
FIG. 1 is a cross-sectional view of an antireflection film according to a first embodiment of the invention. As shown in FIG. 1, the antireflection film 10 according to the first embodiment of the present invention includes a base film 12, a hard coat layer 16 formed on the surface of the base film 12, and a hard coat layer 16. and a low refractive index layer 14 as an antireflection layer formed on the surface. The antireflection film 10 has a base film 12, a hard coat layer 16, and a low refractive index layer 14 in this order. Preferably, the base film 12 and the hard coat layer 16 are in direct contact with each other without interposing any other layer. Also, the hard coat layer 16 and the low refractive index layer 14 (or layers other than the low refractive index layer 14 constituting the antireflection layer) are preferably in direct contact with each other without any other layer interposed therebetween.

(Base film)
The base film 12 is not particularly limited as long as it has transparency. Examples of the base film 12 include transparent polymer films and glass films. Transparency means that the total light transmittance in the visible light wavelength region is 50% or more, and the total light transmittance is more preferably 85% or more. The total light transmittance can be measured according to JIS K7361-1 (1997). The thickness of the base film 12 is not particularly limited, but is preferably in the range of 2 to 500 μm from the viewpoint of excellent handleability. More preferably, it is within the range of 2 to 200 μm. The term "film" generally refers to a film having a thickness of less than 0.25 mm. .25mm or more shall be included in "film".

Polymer materials for the substrate film 12 include polyester resins such as polyethylene terephthalate resin and polyethylene naphthalate resin, polycarbonate resins, poly(meth)acrylate resins, polystyrene resins, polyamide resins, polyimide resins, polyacrylonitrile resins, polypropylene resins, Polyolefin resins such as polyethylene resins, polycycloolefin resins and cycloolefin copolymer resins, cellulose resins such as triacetyl cellulose resins and diacetyl cellulose resins, polyphenylene sulfide resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl alcohol resins, etc. mentioned. The polymeric material of the base film 12 may be composed of only one of these, or may be composed of a combination of two or more. Among these resins, polyethylene terephthalate resins, polyimide resins, polycarbonate resins, poly(meth)acrylate resins, polycycloolefin resins, cycloolefin copolymer resins, and triacetylcellulose resins are more preferable from the viewpoint of optical properties and durability.

The substrate film 12 may be composed of a single layer composed of a layer containing one or more of the above polymer materials, or a layer containing one or more of the above polymer materials and a layer containing this polymer material. It may be composed of two or more layers, such as a layer containing one or more polymeric materials different from the layer.

The substrate film 12 is preferably made of a material having a carbon-carbon double bond, preferably an ethylenic carbon-carbon double bond, at least at a portion in contact with the hard coat layer 16 . Then, a bond is formed between the thiol group of the polyfunctional secondary thiol contained in the hard coat layer 16 described later and the carbon-carbon double bond of the base film 12, so that the base film 12 and the hard coat The adhesiveness between the layers 16 is improved, which is highly effective in improving the scratch resistance of the antireflection film 10 . In this case, in addition to the form in which the film material itself constituting the base film 12 contains carbon-carbon double bonds, a coating layer is formed on the surface of the film material by applying a functional layer such as a primer treatment or an antistatic layer. When formed, the constituent material of the coating layer may contain a carbon-carbon double bond.

(Hard coat layer)
The hard coat layer 16 contributes to improving the scratch resistance of the antireflection film 10 . The hard coat layer is composed of a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound and a polyfunctional secondary thiol. Ionizing radiation means electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or cross-linking molecules. Examples of ionizing radiation include electromagnetic waves such as ultraviolet rays (UV), X-rays and γ-rays, charged particle beams such as electron beams (EB), α-rays and ion beams. Among these, ultraviolet rays (UV) are particularly preferable from the viewpoint of productivity. Hereinafter, the ionizing radiation-curable composition may be simply referred to as a curable composition. Moreover, in this specification, "(meth)acrylate" means "at least one of acrylate and methacrylate". "(Meth)acryloyl" means "at least one of acryloyl and methacryloyl". "(Meth)acrylic" means "at least one of acrylic and methacrylic". A "(meth)acrylate compound" is a compound having a (meth)acryloyl group, and includes monomers, oligomers, prepolymers, and the like. Hereinafter, the (meth)acrylate compound may be simply referred to as (meth)acrylate.

The (meth)acrylate may be a monofunctional (meth)acrylate or a polyfunctional (meth)acrylate. Alternatively, it may be composed of a combination of a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate. The curable composition more preferably contains a polyfunctional (meth)acrylate as the (meth)acrylate from the viewpoint of improving curability.

(Meth)acrylates include urethane (meth)acrylates, silicone (meth)acrylates, alkyl (meth)acrylates, and aryl (meth)acrylates. Among these, urethane (meth)acrylates, particularly urethane (meth)acrylate oligomers are preferred. Urethane (meth)acrylates include, for example, those obtained by reacting a polyisocyanate compound, a hydroxyl group-containing (meth)acrylate compound, and, if necessary, a polyol compound. Examples of polyisocyanate compounds include diisocyanate compounds such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and 4,4′-diphenylmethane diisocyanate, and their nurate modified products, adduct modified products, biuret modified products, and the like. is mentioned. Examples of hydroxyl group-containing (meth)acrylate compounds include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, trimethylolpropane diacrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and These polyoxyalkylene-modified products, polylactone-modified products and the like are included. Examples of polyol compounds include ethylene glycol, propylene glycol, butanediol, hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, glycerin, trimethylolpropane, pentaerythritol, biphenol and bisphenol. When the curable composition for forming the hard coat layer 16 contains urethane (meth)acrylate as the ionizing radiation curable resin, the hard coat layer 16 has appropriate flexibility, so that the antireflection film 10 is resistant to heat. Flexibility is increased, and it can be suitably used for flexible displays that are repeatedly bent, such as foldable displays and rollable displays. Further, for example, even if the base film 12 is made of polycycloolefin, cycloolefin copolymer, or the like and is relatively fragile, cracking of the base film 12 can be easily suppressed.

It is preferable that the (meth)acrylate constituting the curable composition further contains a pentaerythritol (meth)acrylate compound. Specific examples of pentaerythritol (meth)acrylate compounds include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and tripentaerythritol. Tetra(meth)acrylate, tripentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate and the like can be mentioned. In particular, pentaerythritol tri(meth)acrylate is preferably contained in the curable composition. Furthermore, the pentaerythritol (meth)acrylate compound preferably has a hydroxyl value of 200 mgKOH/g or more and 350 mgKOH/g or more.

The pentaerythritol (meth)acrylate compound is a low-viscosity polyfunctional (meth)acrylate, and when it is contained in the curable composition, the coating properties of the curable composition are improved, so the amount of solvent should be reduced. The curable composition can be applied onto the base film 12 even in the following cases. Therefore, non-uniform structures such as unevenness caused in the drying process of the solvent are suppressed, and the anti-reflection film 10 with good appearance quality is obtained. However, when using a low-viscosity (meth)acrylate, the film may tend to curl due to curing shrinkage. , curing shrinkage can be kept small. Therefore, it is possible to suppress curling of the antireflection film 10 and reduce coating unevenness while ensuring sufficient hardness. The content of the pentaerythritol (meth)acrylate compound in the curable composition is preferably 15% by mass or more, more preferably 20% by mass, relative to 100% by mass of the solid content of the (meth)acrylate compound contained in the curable composition. % or more, more preferably 25 mass % or more. Then, the effect of improving hardness and coatability is highly obtained. On the other hand, its content is preferably 75% by mass or less, more preferably 65% by mass or less, and even more preferably 55% by mass. As a result, a high curl suppression effect can be obtained.

As described above, the curable composition contains a polyfunctional secondary thiol in addition to the (meth)acrylate compound. A polyfunctional secondary thiol is a compound containing two or more secondary thiol groups (mercapto groups; —SH) in the molecule. The curable composition containing a polyfunctional thiol improves the scratch resistance of the antireflection film 10 . This is because the polyfunctional thiol forms a bond with the (meth)acrylate compound in the hard coat layer 16, and the adhesiveness between the hard coat layer 16 and the base film 12 and between the low refractive index layer 14 is It is thought that it depends on the improvement. In particular, when at least the portion of the base film 12 and the low refractive index layer 14 (antireflection layer) that contacts the hard coat layer 16 is composed of a material having a carbon-carbon double bond, the polyfunctional A thiol group of a thiol reacts with a carbon-carbon double bond to form a bond (radical addition reaction), thereby forming a bond between the hard coat layer 16, the base film 12 and the low refractive index layer 14 (antireflection layer). The adhesion of is particularly high.

In particular, when the polyfunctional thiol contained in the curable composition is a secondary thiol, gelation of the curable composition is suppressed as compared with the case where it is a primary thiol. As a result, the storage stability of the uncured curable composition is enhanced. In addition, in the formed hard coat layer 16, fish eye defects due to gelation products are less likely to occur, and the antireflection film 10 having the hard coat layer 16 with high uniformity can be obtained. Furthermore, the secondary thiol has a weaker odor than the primary thiol, and in the manufacturing process of the antireflection film 10, equipment required for exhaust and the like can be simplified. Moreover, from the viewpoint of increasing the hardness of the hard coat layer 16, the polyfunctional thiol is preferably trifunctional or more. In particular, from the viewpoint of suppressing material costs, it is preferable that it is trifunctional or tetrafunctional.

Polyfunctional secondary thiols that can be suitably used for forming the hard coat layer 16 include pentaerythritol tetrakis (3-mercaptobutyrate), pentaerythritol tris (3-mercaptobutyrate), 1,3,5-tris ( 2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinane-2,4,6-trione, trimethylolpropane tris (3-mercaptobutyrate), trimethylolethane tris (3-mercaptobutyrate rate), 1,4-bis(3-mercaptobutyryloxy)butane, and the like. The curable composition may contain only one type of these polyfunctional secondary thiols, or may contain two or more types.

The content of the polyfunctional secondary thiol in the hard coat layer 16 is preferably 3% by mass, more preferably 5% by mass or more, and still more preferably 7% by mass or more, based on the total solid content of the curable composition. good. Then, the effect of improving the abrasion resistance is highly obtained. On the other hand, its content is preferably 35% by mass or less, more preferably 25% by mass or less, and even more preferably 15% by mass or less. Then, it becomes easier to secure the hardness of the hard coat layer 16 .

The curable composition forming the hard coat layer 16 may or may not contain a non-ionizing radiation curable resin in addition to the ionizing radiation curable resin. Moreover, the curable composition forming the hard coat layer 16 may contain a photopolymerization initiator. In addition, if necessary, additives that can be added to the curable composition may be included. Additives include dispersants, leveling agents, antifoaming agents, stabilizing agents, antifouling agents, antibacterial agents, flame retardants, slip agents, antistatic agents, inorganic particles, resin particles and the like. Moreover, a solvent may be contained as necessary.

Examples of non-ionizing radiation curable resins include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include polyester resins, polyether resins, polyolefin resins, and polyamide resins. Thermosetting resins include unsaturated polyester resins, epoxy resins, alkyd resins, phenolic resins, and the like.

Examples of the photopolymerization initiator include alkylphenone-based, acylphosphine oxide-based, and oxime ester-based photopolymerization initiators. Alkylphenone-based photopolymerization initiators include 2,2′-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl- Propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-( 2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzylmethyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-morpholino phenyl)-1-butanone, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, N,N-dimethylaminoacetophenone and the like. Acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2 , 4,4-trimethyl-pentylphosphine oxide. Examples of oxime ester photopolymerization initiators include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), ethanone-1-[9-ethyl-6-(2- methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) and the like. These photopolymerization initiators may be used alone, or two or more of them may be used in combination.

The content of the photopolymerization initiator is preferably in the range of 0.1% by mass or more and 10% by mass or less based on the total solid content of the curable composition. More preferably, it is in the range of 1% by mass or more and 5% by mass or less.

The inorganic particles and resin particles are added to the hard coat layer 16 for the purpose of, for example, preventing blocking of the hard coat layer 16 and adjusting the hard coat layer 16 to have a high refractive index. By forming fine surface irregularities on the hard coat layer 16 by adding inorganic particles and resin particles, a hard coat film composed of the base film 12 and the hard coat layer 16 before forming the low refractive index layer 14 is formed. When wound in a roll, it is easy to suppress blocking where the front and back surfaces adhere. By making the hard coat layer 16 have a high refractive index, the antireflection function can be further enhanced when the low refractive index layer 14 is laminated. A high refractive index refers to a refractive index of 1.50 or more at a measurement wavelength of 589.3 nm, preferably in the range of 1.55 to 1.80, more preferably in the range of 1.60 to 1.70. .

Inorganic particles capable of optically adjusting the hard coat layer 16 to a high refractive index include oxides of metals such as titanium, zirconium, tin, zinc, silicon, niobium, aluminum, chromium, magnesium, germanium, gallium, antimony, and platinum. and metal oxide particles. These may be used alone as optically adjustable inorganic particles, or may be used in combination of two or more. Among these, titanium oxide and zirconium oxide are particularly preferable from the viewpoint of being excellent in both high refractive index and transparency. Examples of resin particles include resins such as (meth)acrylic resins, styrene resins, styrene-(meth)acrylic resins, urethane resins, polyamide resins, silicone resins, epoxy resins, phenolic resins, polyethylene resins, and cellulose. resin particles. These resin particles may be used singly or in combination of two or more.

Although the thickness of the hard coat layer 16 is not particularly limited, it is preferably 0.5 μm or more from the viewpoint of having sufficient hardness. More preferably, it is 0.75 μm or more. In addition, from the viewpoint of easily suppressing curling caused by a difference in heat shrinkage with the base film 12, the thickness is preferably 20 μm or less. More preferably, it is 10 µm or less. The thickness of the hard coat layer 16 is the thickness of the relatively smooth portion in the thickness direction where there are no irregularities caused by inorganic particles or resin particles.

The arithmetic mean roughness Ra of the surface of the hard coat layer 16 on which surface irregularities are formed is preferably in the range of 0.3 to 20 nm from the viewpoint of blocking. More preferably, it is within the range of 0.5 to 10 nm.

Solvents used in the curable composition forming the hard coat layer 16 include ethanol, isopropyl alcohol (IPA), n-butyl alcohol (NBA), ethylene glycol monomethyl ether (EGM), and ethylene glycol monoisopropyl ether (IPG). , alcohol solvents such as propylene glycol monomethyl ether (PGM) and diethylene glycol monobutyl ether; ketone solvents such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone and acetone; aromatic solvents such as toluene and xylene; Ester-based solvents such as ethyl acetate (EtAc), propyl acetate, isopropyl acetate and butyl acetate (BuAc), and amide-based solvents such as N-methylpyrrolidone, acetamide and dimethylformamide are included. These may be used individually by 1 type as a solvent, and may be used in combination of 2 or more types.

The solid content concentration (concentration of components other than the solvent) of the curable composition may be appropriately determined in consideration of coatability, film thickness, and the like. For example, it may be 1 to 90% by mass, 1.5 to 80% by mass, 2 to 70% by mass, and the like.

(Low refractive index layer)
In the antireflection film 10 according to this embodiment, a low refractive index layer 14 is provided as an antireflection layer on the surface of the hard coat layer 16 . The low refractive index layer 14 has a refractive index lower than that of the hard coat layer 16, and exhibits an antireflection effect due to a significant difference in refractive index from the hard coat layer 16. FIG. The refractive index of the low refractive index layer 14 is preferably in the range of 1.29-1.45, more preferably 1.32-1.43. The refractive index of the low refractive index layer 14 is the refractive index at the measurement wavelength of 589.3 nm. Although the composition of the low refractive index layer 14 is not particularly limited, it preferably contains inorganic oxide particles 18, hollow silica particles 22, a fluorine-containing compound, and a binder resin. As the low refractive index layer 14, the one described in Patent Document 1 can be suitably applied.

The low refractive index layer 14 is preferably made of a material having a carbon-carbon double bond, preferably an ethylenic carbon-carbon double bond, at least at a portion in contact with the hard coat layer 16 . Then, a bond is formed between the thiol group of the polyfunctional secondary thiol contained in the hard coat layer 16 and the carbon-carbon double bond of the low refractive index layer 14, thereby forming the low refractive index layer 14 and the hard coat layer. The adhesiveness between 16 is improved, showing a high effect in improving the scratch resistance of the antireflection film 10 . For example, a carbon-carbon double bond of (meth)acrylate contained in the low refractive index layer 14 as a binder resin can play this role.

As the binder resin, from the viewpoint of scratch resistance of the low refractive index layer 14, a cured product of a thermosetting compound, a cured product of an ultraviolet curable compound, or the like is preferable. Moreover, from the viewpoint of productivity and the like, a cured product of an ultraviolet curable compound is more preferable.

Examples of UV-curable resins include monomers, oligomers and prepolymers having UV-reactive groups. Examples of the UV-reactive reactive group include a radical polymerization type reactive group having an ethylenically unsaturated bond such as an acryloyl group, a methacryloyl group, an allyl group, and a vinyl group, and a cationic polymerization type reactive group such as an oxetanyl group. is mentioned. Among these, acryloyl group, methacryloyl group and oxetanyl group are more preferable, and acryloyl group and methacryloyl group are particularly preferable. That is, (meth)acrylates are particularly preferred.

(Meth)acrylates include urethane (meth)acrylates, silicone (meth)acrylates, alkyl (meth)acrylates, and aryl (meth)acrylates. (Meth) acrylate may be composed of only monofunctional (meth) acrylate, may be composed of polyfunctional (meth) acrylate, monofunctional (meth) acrylate and polyfunctional (meth) acrylate It may be composed of a combination of (Meth)acrylates more preferably include polyfunctional (meth)acrylates.

Monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, and isobutyl (meth)acrylate. , t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl ( meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate ) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, bornyl (meth) acrylate, tricyclodeca Nil (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, 2-naphthylmethyl (meth)acrylate ) acrylate, phenoxyethyl (meth) acrylate, phenoxy-2-methylethyl (meth) acrylate, phenoxyethoxyethyl (meth) acrylate, 3-phenoxy-2-hydroxypropyl (meth) acrylate, 2-phenylphenoxyethyl (meth) Acrylates, 4-phenylphenoxyethyl (meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2- Hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) ) acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and the like.

Polyfunctional (meth)acrylates include bifunctional (meth)acrylates, trifunctional (meth)acrylates, tetrafunctional (meth)acrylates, and the like. More specifically, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, Diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate , pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol tetra(meth)acrylate, tripentaerythritol penta(meth)acrylate ) acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate and the like.

The ultraviolet curable resin may be composed of one kind of the above-described (meth)acrylates alone, or may be composed of two or more kinds. From the viewpoint of improving scratch resistance, the UV-curable resin preferably contains a pentafunctional or higher polyfunctional (meth)acrylate, and the content of the pentafunctional or higher polyfunctional (meth)acrylate should be increased. is preferred.

Moreover, it is preferable that a polyfunctional (meth)acrylate contains a dimer. Dimers of polyfunctional (meth)acrylates are excellent in curing speed and can easily increase the curing rate of the curable composition, so that the scratch resistance can be further improved. Among them, it is preferable to include at least one selected from the group consisting of dimers of pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, More preferably, it contains at least one selected from the group consisting of dimers of pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

The content of the dimer is preferably in the range of 25 to 50% by mass based on the total solid content of the polyfunctional (meth)acrylate from the viewpoint of scratch resistance, transparency, and solubility in solvents. . More preferably, it is in the range of 30 to 40% by mass.

The inorganic oxide particles 18 are included in the low refractive index layer 14 to form projections on the surface of the low refractive index layer 14 . By forming projections on the surface of the low refractive index layer 14 by the inorganic oxide particles 18, the low refractive index layer 14 can have good scratch resistance.

The inorganic oxide particles 18 may be solid particles or hollow particles. The inorganic oxide particles 18 are preferably solid particles. Solid particles are particles that have substantially no cavities inside the particles, and the proportion of cavities is less than 5% of the volume of the solid particles. Hollow particles are particles that have cavities inside the particles, and that the proportion of cavities is 5% or more of the volume of the hollow particles. When the inorganic oxide particles 18 are solid particles, the abrasion resistance of the low refractive index layer 14 is improved, and the abrasion resistance of the antireflection film 10 is improved. If the inorganic oxide particles 18 are hollow particles, the refractive index of the low refractive index layer 14 can be lowered to reduce light reflection. In the hollow particles, the proportion of voids is preferably 10 to 80% of the volume of the hollow particles. More preferably 20 to 60%, still more preferably 30 to 60%. When the ratio of voids is 10% or more, the refractive index can be lowered to reduce the reflection of light. A decrease in the dispersibility of the inorganic oxide particles 18 can be suppressed when the void ratio is 80% or less.

Examples of the inorganic oxide particles 18 include metal oxide particles made of oxides of metals such as titanium, zirconium, silicon, aluminum, and calcium. These may be used singly as the inorganic oxide particles 18, or may be used in combination of two or more. Among these, silica particles and alumina particles are preferred, and alumina particles are particularly preferred, from the viewpoints of low refractive index, excellent transparency, and high hardness.

The shape of the inorganic oxide particles 18 is not particularly limited, and may be spherical, needle-like, scale-like, rod-like, fibrous, amorphous, or the like. Among these, a spherical shape is preferable.

The inorganic oxide particles 18 form projections on the surface of the low refractive index layer 14, and in order to obtain good scratch resistance, the average particle diameter r of the inorganic oxide particles 18 and the average thickness of the low refractive index layer 14 are The difference in d (rd) is preferably 10 nm or more. The difference (rd) is more preferably 15 nm or more, still more preferably 18 nm or more. On the other hand, the difference (r−d) is preferably 300 nm or less from the viewpoint of maintaining transparency by suppressing the height of the formed protrusions. It is more preferably 200 nm or less, still more preferably 100 nm or less.

The average particle diameter r of the inorganic oxide particles 18 depends on the average thickness d of the low refractive index layer 14, but is preferably within the range of 60 to 400 nm. It is more preferably within the range of 70 to 300 nm, still more preferably within the range of 90 to 200 nm. The average particle diameter r of the inorganic oxide particles 18 is a volume-based average arithmetic value obtained by a laser diffraction/scattering method according to JIS Z8825, and is not only a primary particle diameter but also a secondary particle diameter that is an aggregate of particles. Also includes

The content of the inorganic oxide particles 18 in the low refractive index layer 14 is preferably 0.1% by mass or more and 4.0% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14 . When the content of the inorganic oxide particles 18 in the low refractive index layer 14 is 0.1% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 14, excellent scratch resistance can be obtained. From this point of view, the content of the inorganic oxide particles 18 in the low refractive index layer 14 is more preferably 0.5% by mass or more, more preferably 1% by mass with respect to 100% by mass of the solid content of the low refractive index layer 14. .0% by mass or more. When the content of the inorganic oxide particles 18 in the low refractive index layer 14 is 4.0% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14, high transparency can be obtained. From this point of view, the content of the inorganic oxide particles 18 in the low refractive index layer 14 is more preferably 3.5% by mass or less, more preferably 3.5% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14. .2% by mass or less. In addition, the solid content of the low refractive index layer 14 as used herein refers to components other than liquid components at room temperature that are not fixed in the binder resin in the low refractive index layer 14 . The solid content of the low refractive index layer 14 includes inorganic oxide particles 18, hollow silica particles 22, a binder resin, a fluorine-containing compound immobilized in the binder resin, and the like. Oil components as additives and surfactants that are not immobilized in the binder resin are not included.

The hollow silica particles 22 are particles having an average particle diameter smaller than the average thickness of the low refractive index layer 14 . The hollow silica particles 22 are preferably particles having an average particle diameter smaller than that of the inorganic oxide particles 18 that form projections on the surface of the low refractive index layer 14 . The hollow silica particles 22 are particles that do not substantially contribute to the formation of surface irregularities of the low refractive index layer 14 . The hollow silica particles 22 are particles having cavities inside the particles, and are particles whose volume ratio is 5% or more of the volume. The term “hollow” refers to a core-shell structure consisting of an outer shell and internal cavities, or a porous structure having a large number of cavities. Since the hollow silica particles 22 have a hollow structure, the refractive index of the low refractive index layer 14 can be lowered to reduce light reflection. The shape of the hollow silica particles 22 is not particularly limited, but is preferably spherical, spindle-shaped, egg-shaped, tabular, cubic, amorphous, or the like. Among these, a spherical shape, a tabular shape, a cubic shape, and the like are particularly preferable.

In the hollow silica particles 22, the ratio of voids is preferably 10 to 80% of the volume. More preferably 20 to 60% by volume, still more preferably 30 to 60% by volume. If the cavity ratio is 10% or more of the volume, the refractive index can be lowered to reduce light reflection. When the ratio of voids is 80% or less of the volume, deterioration of the dispersibility of the hollow silica particles 22 can be suppressed.

Although it depends on the average thickness of the low refractive index layer 14, the average particle diameter of the hollow silica particles 22 is preferably 5 nm or more and 100 nm or less. It is more preferably 20 nm or more and 80 nm or less, and still more preferably 40 nm or more and 70 nm or less. When the average particle size of the hollow silica particles 22 is within these preferred ranges, the low refractive index layer 14 can have excellent antireflection effect and transparency. The average particle size is a volume-based average arithmetic value obtained by a laser diffraction/scattering method according to JIS Z8825. It includes not only the primary particle size but also the secondary particle size, which is an aggregate of particles.

The refractive index of the hollow silica particles 22 is preferably within the range of 1.01 to 1.45. It is more preferably in the range of 1.15 to 1.38, still more preferably in the range of 1.15 to 1.35. Within this range, an excellent antireflection effect can be obtained.

The content of the hollow silica particles 22 in the low refractive index layer 14 is preferably 6.0% by mass or more and 49.9% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14 . When the content of the hollow silica particles 22 in the low refractive index layer 14 is 6.0% by mass with respect to 100% by mass of the solid content of the low refractive index layer 14, excellent antireflection properties can be obtained. From this point of view, the content of the hollow silica particles 22 in the low refractive index layer 14 is more preferably 10% by mass or more, more preferably 20% by mass or more, relative to 100% by mass of the solid content of the low refractive index layer 14. , particularly preferably 30% by mass or more. When the content of the hollow silica particles 22 in the low refractive index layer 14 is 49.9% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14, deterioration of scratch resistance is suppressed. From this point of view, the content of the hollow silica particles 22 in the low refractive index layer 14 is more preferably 45% by mass or less, more preferably 40% by mass or less, relative to 100% by mass of the solid content of the low refractive index layer 14. is.

The total amount of the inorganic oxide particles 18 and the hollow silica particles 22 in the low refractive index layer 14 is preferably 10% by mass or more and 50% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14 . When the total amount of the inorganic oxide particles 18 and the hollow silica particles 22 in the low refractive index layer 14 is 10% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 14, excellent scratch resistance can be obtained. can. From this point of view, the total amount of the inorganic oxide particles 18 and the hollow silica particles 22 in the low refractive index layer 14 is more preferably 20% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 14, and further Preferably, it is 30% by mass or more. On the other hand, when the total amount of the inorganic oxide particles 18 and the hollow silica particles 22 in the low refractive index layer 14 is 50% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14, the inorganic Since the oxide particles 18 and the hollow silica particles 22 can be sufficiently retained, excellent scratch resistance can be obtained. From this point of view, the total amount of the inorganic oxide particles 18 and the hollow silica particles 22 in the low refractive index layer 14 is more preferably 48% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14, and further It is preferably 46% by mass or less, particularly preferably 43% by mass or less.

A fluorine-containing compound can function as an antifouling agent. Moreover, since the slipperiness of the surface of the low refractive index layer 14 is improved, it is possible to contribute to the improvement of scratch resistance. Examples of fluorine-containing compounds include (meth)acrylates containing perfluoroalkyl groups. Such compounds include "KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd., "Megafac RS-75" manufactured by DIC, "OPTOOL DAC-HP" manufactured by Daikin Industries, and "Ftergent 601AD" manufactured by Neos. Such a fluorine-containing compound can suppress adhesion of stains and fingerprints and facilitate removal of stains and fingerprints.

The content of the fluorine-containing compound in the low refractive index layer 14 is preferably 1.0% by mass or more and 15.0% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14 . When the content of the fluorine-containing compound in the low refractive index layer 14 is 1.0% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 14, the slipperiness of the surface of the low refractive index layer 14 is improved, Improves scratch resistance. Moreover, antifouling property improves. From this point of view, the content of the fluorine-containing compound in the low refractive index layer 14 is more preferably 2.0% by mass or more, more preferably 3.0% by mass, based on 100% by mass of the solid content of the low refractive index layer 14. % by mass or more. When the content of the fluorine-containing compound in the low refractive index layer 14 is 15.0% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 14, deterioration in scratch resistance can be suppressed. From this point of view, the content of the fluorine-containing compound in the low refractive index layer 14 is more preferably 13.0% by mass or less, more preferably 10.0% by mass, based on 100% by mass of the solid content of the low refractive index layer 14. % by mass or less, particularly preferably 5.0% by mass or less.

The average thickness d of the low refractive index layer 14 is preferably within the range of 60-160 nm, more preferably within the range of 70-140 nm, further preferably within the range of 80-120 nm. Within this range, good luminosity reflectance can be obtained, and light reflection can be reduced. The average thickness of the low refractive index layer 14 is the thickness of a relatively smooth portion where the inorganic oxide particles 18 are not present in the thickness direction.

The low refractive index layer 14 may contain additives and the like as necessary. Such additives include antifouling agents, dispersants, leveling agents, antifoaming agents, stabilizing agents, antibacterial agents, flame retardants, slip agents, refractive index modifiers, and the like.

The low refractive index layer 14 can be formed using a composition containing inorganic oxide particles 18, hollow silica particles 22, a fluorine-containing compound, and a binder resin. The fluorine-containing compound and the binder resin preferably have an ultraviolet reactive group. A (meth)acryloyl group etc. are mentioned as an ultraviolet-reactive reactive group. When the fluorine-containing compound and the binder resin have an ultraviolet reactive group, the low refractive index layer 14 has improved scratch resistance, and the antireflection film 10 has improved scratch resistance. The composition for forming the low refractive index layer 14 preferably contains a photopolymerization initiator when the binder resin contains a substance having an ultraviolet-reactive reactive group (ultraviolet-curable resin). The composition for forming the low refractive index layer 14 may contain a solvent, if necessary. The binder resin of the low refractive index layer 14 may be composed of an ultraviolet curable resin, may be composed of a non-ultraviolet curable resin, or may be a combination of an ultraviolet curable resin and a non-ultraviolet curable resin. may be configured.

Examples of non-ultraviolet curable resins include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include polyester resins, polyether resins, polyolefin resins, and polyamide resins. Thermosetting resins include unsaturated polyester resins, epoxy resins, alkyd resins, phenolic resins, and the like.

Examples of the photopolymerization initiator include alkylphenone-based, acylphosphine oxide-based, and oxime ester-based photopolymerization initiators. Alkylphenone-based photopolymerization initiators include 2,2′-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl- Propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-( 2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzylmethyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-morpholino phenyl)-1-butanone, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, N,N-dimethylaminoacetophenone and the like. Acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2 , 4,4-trimethyl-pentylphosphine oxide. Examples of oxime ester photopolymerization initiators include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), ethanone-1-[9-ethyl-6-(2- methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) and the like. These photopolymerization initiators may be used alone, or two or more of them may be used in combination.

The content of the photopolymerization initiator is preferably in the range of 0.1 to 10 mass % based on the total solid content of the composition for forming the low refractive index layer 14 . More preferably, it is in the range of 1 to 5% by mass.

Solvents used in the composition for forming the low refractive index layer 14 include alcohol solvents such as ethylene glycol monomethyl ether (EGM), propylene glycol monomethyl ether (PGM), and diethylene glycol monobutyl ether, methyl ethyl ketone (MEK), and methyl isobutyl. Ketone solvents such as ketone (MIBK), cyclohexanone and acetone; aromatic solvents such as toluene and xylene; and amide solvents such as N-methylpyrrolidone, acetamide and dimethylformamide. These may be used individually by 1 type as a solvent, and may be used in combination of 2 or more types.

(Manufacturing method of antireflection film)
The antireflection film 10 is formed by applying a composition for forming the hard coat layer 16 on the surface of the base film 12, drying it if necessary, and then curing it by irradiating energy rays such as ultraviolet rays to form the base film 12. After forming the hard coat layer 16 on the surface of the hard coat layer 16, a composition for forming the low refractive index layer 14 is applied on the surface of the hard coat layer 16, dried as necessary, and irradiated with energy rays such as ultraviolet rays. It can be manufactured by curing with a hard coat layer 16 to form the low refractive index layer 14 on the surface of the hard coat layer 16 . At this time, in order to improve the adhesion between the base film 12 and the hard coat layer 16, the surface of the base film 12 may be subjected to surface treatment before coating. Examples of surface treatment include corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment.

For coating of the composition forming the hard coat layer 16 and the composition forming the low refractive index layer 14, for example, a reverse gravure coating method, a direct gravure coating method, a die coating method, a bar coating method, a wire bar coating method, Various coating methods such as roll coating method, spin coating method, dip coating method, spray coating method, knife coating method, and kiss coating method, and various printing methods such as inkjet method, offset printing, screen printing, and flexographic printing. can be done.

The drying process is not particularly limited as long as the solvent and the like used in the coating liquid can be removed, but it is preferably carried out at a temperature of 50 to 150° C. for about 10 to 180 seconds. Especially, the drying temperature is preferably 50 to 120°C.

A high-pressure mercury lamp, an electrodeless (microwave type) lamp, a xenon lamp, a metal halide lamp, or any other ultraviolet irradiation device can be used for ultraviolet irradiation. UV irradiation may be performed under an inert gas atmosphere such as nitrogen, if necessary. The amount of ultraviolet irradiation is not particularly limited, but is preferably 50-800 mJ/cm ² , more preferably 100-300 mJ/cm ² .

The arithmetic mean roughness Sa of the surface of the low refractive index layer 14 is preferably 1.0 to 20 nm, more preferably 3.0 to 15 nm, and still more preferably 5.0 nm, from the viewpoint of good finger sliding property and scratch resistance. 0 to 10 nm.

The haze of the antireflection film 10 is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less from the viewpoint of good visibility.

The luminosity reflectance of the antireflection film 10 is preferably as low as possible, more preferably 2.0% or less, and even more preferably 1.0% or less.

The antireflection film 10 having the above configuration includes the base film 12, the hard coat layer 16 formed on the surface of the base film 12, and the low refractive index layer 14 formed on the surface of the hard coat layer 16 ( The hard coat layer 16 is composed of a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound and a polyfunctional secondary thiol. Due to the contribution of this hard coat layer 16, the antireflection film 10 has excellent scratch resistance.

<Other forms of antireflection film>
The antireflection film according to the present invention is not limited to the structure of the antireflection film 10 according to the first embodiment. Other embodiments of the antireflection film according to the present invention will be described below.

(Second embodiment)
FIG. 2 shows an antireflection film 20 according to the second embodiment. The antireflection film 20 according to the second embodiment includes a base film 12, a hard coat layer 16 formed on the surface of the base film 12, and a high refractive index layer formed on the surface of the hard coat layer 16. 17 and a low refractive index layer 14 formed on the surface of the high refractive index layer 17 . The antireflection film 20 has a base film 12, a hard coat layer 16, a high refractive index layer 17, and a low refractive index layer 14 in order from the base film 12 side. In this structure, the low refractive index layer 14 and the high refractive index layer 17 serve as antireflection layers.

The antireflection film 20 according to the second embodiment has a high refractive index layer 17 between the hard coat layer 16 and the low refractive index layer 14 compared to the antireflection film 10 according to the first embodiment. Except for this point, it is the same as the antireflection film 10 according to the first embodiment, and the description of the same configuration will be omitted.

The high refractive index layer 17 can be formed by appropriately selecting from the materials described for the hard coat layer 16 . The refractive index of the high refractive index layer 17 is preferably within the range of 1.55-1.80, more preferably within the range of 1.60-1.70. The refractive index of the high refractive index layer 17 is the refractive index at the measurement wavelength of 589.3 nm. The refractive index of the high refractive index layer 17 can be adjusted by selecting the binder resin, the inorganic particles, and the resin particles, the blending amount, and the like.

Although the average thickness of the high refractive index layer 17 varies depending on the setting of the refractive index, the antireflection function can be further enhanced by setting the average thickness to 50 nm or more and 200 nm or less, for example.

In the antireflection film 10 according to the first embodiment described above, the low refractive index layer 14 formed on the surface of the hard coat layer 16 constitutes an antireflection layer, In the antireflection film 20, the high refractive index layer 17 and the low refractive index layer 14 are laminated in this order on the surface of the hard coat layer 16 to form an antireflection layer. The structure is not particularly limited as long as the layer can reduce the For example, an intermediate refractive index layer may be further provided between the hard coat layer 16 and the high refractive index layer 17 of the antireflection film 20 according to the second embodiment, and the antireflection layer may have a three-layer structure. The medium refractive index layer is a layer having a refractive index between the low refractive index layer 14 and the high refractive index layer 17. By providing the medium refractive index layer, the antireflection property can be further enhanced. Furthermore, an antifouling layer may be formed on the surface of the antireflection layer.

Regardless of the structure of the antireflection layer, at least the portion of the antireflection layer in contact with the hard coat layer 16 is made of a material having a carbon-carbon double bond, preferably an ethylenic carbon-carbon double bond. It is preferable that Then, a bond is formed between the thiol group of the polyfunctional secondary thiol contained in the hard coat layer 16 and the carbon-carbon double bond of the base film 12, so that between the antireflection layer and the hard coat layer 16 , and is highly effective in improving the scratch resistance of the antireflection film. For example, of the antireflection layers, when the layer in contact with the hard coat layer 16 is composed of a cured product of an ionizing radiation curable material containing (meth)acrylate, the carbon-carbon double layer of (meth)acrylate Conjugation can play this role.

(Third embodiment)
FIG. 3 shows an antireflection film 30 according to the third embodiment. The antireflection film 30 according to the third embodiment includes a base film 12, a hard coat layer 16 formed on one surface of the base film 12, and a low refractive index layer 16 formed on the surface of the hard coat layer 16. a rate layer 14; Moreover, it has a transparent adhesive layer 24 on the other surface of the base film 12 . A release film 26 is arranged on the surface of the transparent adhesive layer 24 as necessary. The release film 26 functions as a protective layer for the transparent adhesive layer 24 before use, and is peeled off from the transparent adhesive layer 24 during use.

The antireflection film 30 according to the third embodiment differs from the antireflection film 10 according to the first embodiment in that it has a transparent adhesive layer 24 on the other surface of the base film 12. are the same as those of the antireflection film 10 according to the first embodiment, and descriptions of the same configurations are omitted.

The transparent adhesive layer 24 is for attaching the antireflection film 30 to the surface of a display or the like with good adhesion. In addition, the antireflection film 30 has the effect of preventing scattering of glass such as a display by having the transparent adhesive layer 24 . That is, the antireflection film 30 also has a function as a scattering prevention film.

The adhesive composition forming the transparent adhesive layer 24 can contain known adhesive resins such as acrylic adhesives, silicone adhesives, and urethane adhesives. Among them, acrylic pressure-sensitive adhesives are preferable from the viewpoint of optical transparency and heat resistance. The adhesive composition preferably contains a cross-linking agent in order to increase the cohesive strength of the transparent adhesive layer 24 . Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and chelate-based cross-linking agents.

The adhesive composition may contain additives as necessary. Examples of additives include known additives such as plasticizers, silane coupling agents, surfactants, antioxidants, fillers, curing accelerators and curing retarders. Moreover, from the viewpoint of productivity, etc., it may be diluted using an organic solvent.

Although the thickness of the transparent adhesive layer 24 is not particularly limited, it is preferably in the range of 5 to 100 μm. More preferably, it is within the range of 10 to 50 μm.

The transparent adhesive layer 24 is formed by directly applying an adhesive composition on the other surface of the base film 12, or by applying an adhesive composition on the surface of the release film 26, and then applying the adhesive composition to the substrate. A method of transferring onto the other surface of the material film 12, applying an adhesive composition on the surface of the first release film to form it, then bonding the second release film, It can be formed by a method of peeling off the mold film and transferring it onto the other surface of the base film 12 .

The transparent adhesive layer 24 preferably has an adhesive force to glass of 4 N/25 mm or more from the viewpoint of the glass scattering prevention effect. It is more preferably 6 N/25 mm or more, still more preferably 10 N/25 mm or more.

(Fourth embodiment)
FIG. 4 shows an antireflection film 40 according to a fourth embodiment. The antireflection film 40 according to the fourth embodiment includes a base film 12, a hard coat layer 16 formed on one surface of the base film 12, and a low refractive index film formed on the surface of the hard coat layer 16. and a protective film 32 disposed on the surface of the low refractive index layer 14 with an adhesive layer 28 interposed therebetween. Moreover, it has a transparent adhesive layer 24 on the other surface of the base film 12 . A release film 26 is arranged on the surface of the transparent adhesive layer 24 as necessary.

Compared with the antireflection film 30 according to the third embodiment, the antireflection film 40 according to the fourth embodiment has a protective film 32 on the surface of the low refractive index layer 14 via the adhesive layer 28. Other than this, it is the same as the antireflection film 30 according to the third embodiment, and the description of the same configuration will be omitted.

The protective film 32 can prevent the surface of the low refractive index layer 14 from being scratched during handling such as continuous processing by a roll process or bonding to a display or the like. The protective film 32 is attached to the surface of the low refractive index layer 14 via the adhesive layer 28 . The protective film 32 is peeled off from the surface of the low refractive index layer 14 together with the adhesive layer 28 after processing. Therefore, in the adhesive layer 28, the adhesive force between the protective film 32 and the adhesive layer 28 is stronger than the adhesive force between the low refractive index layer 14 and the adhesive layer 28, and the adhesive force between the low refractive index layer 14 and the adhesive layer 28 is stronger. The adhesive force between the agent layers 28 is adjusted so that interfacial peeling is possible.

The materials composing the protective film 32 can be appropriately selected from the materials exemplified as the materials composing the base film 12 . The thickness of the protective film 32 is not particularly limited, but may be in the range of 2-500 μm, or in the range of 2-200 μm.

The adhesive that forms the adhesive layer 28 is not particularly limited, and an acrylic adhesive, a silicone adhesive, a urethane adhesive, or the like can be preferably used. In particular, acrylic pressure-sensitive adhesives are suitable because they are excellent in transparency and heat resistance. The acrylic pressure-sensitive adhesive is preferably formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer and a cross-linking agent.

(Meth)acrylic polymers are homopolymers or copolymers of (meth)acrylic monomers. (Meth)acrylic monomers include alkyl group-containing (meth)acrylic monomers, carboxyl group-containing (meth)acrylic monomers, and hydroxyl group-containing (meth)acrylic monomers.

Examples of alkyl group-containing (meth)acrylic monomers include (meth)acrylic monomers having an alkyl group having 2 to 30 carbon atoms. The alkyl group having 2 to 30 carbon atoms may be linear, branched, or cyclic. More specifically, the alkyl group-containing (meth)acrylic monomer includes, for example, isostearyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, dodecyl (meth)acrylate, (meth)acrylic acid ) Decyl acrylate, isononyl (meth) acrylate, nonyl (meth) acrylate, isooctyl (meth) acrylate, octyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, ( meth)pentyl acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, propyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, etc. are mentioned.

Carboxyl group-containing (meth)acrylic monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate. The carboxyl group may be located at the end of the alkyl chain or in the middle of the alkyl chain.

Examples of hydroxyl group-containing (meth)acrylic monomers include hydroxylauryl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxybutyl (meth)acrylate, Hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, and the like. The hydroxyl group may be located at the end of the alkyl chain or may be located in the middle of the alkyl chain.

The (meth)acrylic monomer forming the (meth)acrylic polymer may be one of the above, or may be a combination of two or more.

Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, metal chelate-based cross-linking agents, metal alkoxide-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and melamine-based cross-linking agents. . The cross-linking agent may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition may contain other additives in addition to the (meth)acrylic polymer and the cross-linking agent. Other additives include cross-linking accelerators, cross-linking retarders, tackifying resins (tackifiers), antistatic agents, silane coupling agents, plasticizers, release aids, pigments, dyes, wetting agents, thickeners. , ultraviolet absorbers, preservatives, antioxidants, metal deactivators, alkylating agents, flame retardants and the like. These are appropriately selected and used according to the application and purpose of use of the pressure-sensitive adhesive.

Although the thickness of the adhesive layer 28 is not particularly limited, it is preferably in the range of 1 to 10 μm. More preferably, it is in the range of 2-7 μm.

Although the embodiments of the present invention have been described above, the present invention is by no means limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, in the above-described embodiment, the surface of the base film 12 may be subjected to surface treatment. good too.

4, the protective film 32 is added to the antireflection film 30 of the third embodiment shown in FIG. 3, but the antireflection film 30 of the first embodiment shown in FIG. 10, or may be added to the antireflection film 20 of the second embodiment shown in FIG.

Various functional layers such as a gas barrier property improving layer, an antistatic layer, and an oligomer block layer may be provided in advance on the surface of the base film 12 before forming each layer.

The antistatic layer is provided for the purpose of, for example, reducing adhesion of surrounding dust due to separation electrification or frictional electrification. The antistatic layer is preferably a layer made of a composition for forming an antistatic layer containing an antistatic agent.

Examples of antistatic agents include cationic antistatic agents such as quaternary ammonium salts and pyridium salts; anionic antistatic agents such as alkali metal salts such as sulfonic acid, phosphoric acid and carboxylic acid; Amphoteric antistatic agents such as esters, nonionic antistatic agents such as amino alcohols, glycerin and polyethylene glycol, ionic compounds, conductive polymers such as polyacetylene and polythiophene, metal oxide particles, carbon nanotubes, etc. conductive particles, conductive fibers, and the like. Among these, antistatic agents, metal particles, and metal oxide particles, which are obtained by combining a dopant with a conductive polymer such as polyacetylene or polythiophene, are used from the viewpoint of less humidity dependence and prevention of bleeding out from the antistatic layer. preferable.

Specific examples of the antistatic agent made of the conductive polymer include polyacetylene, polyaniline, polythiophene, polypyrrole, polyphenylene sulfide, poly(1,6-heptadiyne), polybiphenylene (polyparaphenylene), polyparaphenylene sulfide, Examples include conductive polymers such as polyphenylacetylene, poly(2,5-thienylene), or derivatives thereof, preferably polythiophene-based conductive organic polymers (e.g., 3,4-ethylenedioxythiophene ( PEDOT), etc.). These antistatic agents may be used singly or in combination of two or more.

The content of the antistatic agent is preferably in the range of 1 to 50% by mass based on the total solid content of the antistatic layer-forming composition. It is more preferably in the range of 5 to 40% by mass, still more preferably in the range of 10 to 20% by mass. If the content is 1% by mass or more, good antistatic properties can be imparted, and if it is 50% by mass or less, a highly transparent film with good total light transmittance can be obtained.

The antistatic layer may have a binder resin. The binder resin is not particularly limited as long as it is compatible with or can be mixed and dispersed with the antistatic agent, and may be a curable resin or a thermoplastic resin.

Examples of thermoplastic resins include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyimide resins such as polyimide and polyamideimide; and polyamide 6, polyamide 6,6, polyamide 12, polyamide 11, and the like. Examples include polyamide resin, polyvinylidene fluoride, acrylic resin, vinyl resin such as polyvinyl alcohol, and urethane resin.
As the curable resin, the same material as that used for forming the hard coat layer 16 can be used.

The thickness of the antistatic layer is preferably 1 nm to 5 μm, more preferably 10 nm to 1 μm, still more preferably 30 nm to 300 nm, from the viewpoint of preventing static charge.

The present invention will be described in detail below using examples and comparative examples.

<Preparation of composition for forming hard coat layer>
Each component was blended so as to have the formulation composition (% by mass of the total solid content) shown in Table 1, ethyl acetate was added so that the solid content concentration shown in Table 1 was obtained, and the composition for forming a hard coat layer prepared the product.

Materials used as constituents of the composition for forming the hard coat layer are as follows.
・Ultraviolet curable resin 1-DIC “Luxidia ESS-620”, urethane acrylate resin, solvent: ethyl acetate, solid content concentration: 79% by mass
・Ultraviolet curable resin 2-Toagosei “Aronix M-933”, pentaerythritol acrylated reaction product mainly composed of pentaerythritol triacrylate, hydroxyl value: 250 to 300 mgKOH / g, solid content concentration: 100 mass %
・ Polyfunctional secondary thiol - "Karenzu MT PE1" manufactured by Showa Denko, a mixture of pentaerythritol tetrakis (3-mercaptobutyrate) and pentaerythritol tris (3-mercaptobutyrate), solid content concentration: 100% by mass
· Leveling agent - Neos "Ftergent 602A", fluorine-based leveling agent, solvent: ethyl acetate, solid content concentration: 50% by mass
- Photopolymerization initiator - IGM Resins B.I. V. manufactured by "Omnirad 127", 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one

<Preparation of composition for forming low refractive index layer>
In mass% of the total solid content, 55% by mass of ultraviolet curable resin, 3.8% by mass of alumina sol, 8% by mass of fluorine-containing compound, 30% by mass of hollow silica particles, and 3% by mass of photopolymerization initiator, A composition for forming a low refractive index layer was prepared by blending each component and adjusting the solid content concentration to 3% by mass using a solvent (MEK/PGM=1/3).

Materials used as constituents of the composition for forming a low refractive index layer are as follows.
・Ultraviolet curable resin - Toagosei "Aronix MT-3041", polyfunctional acrylate, solid content concentration: 100% by mass
・ Aluminasol - Toyochem "Riodulas KT-110AL", alumina particles (average particle diameter: 110 nm) 25% by mass, photosensitive monomer and resin 15% by mass, solvent (MEK, cyclohexanone, aliphatic solvent)
・ Fluorine-containing compound - "KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd., perfluoroalkyl group-containing (meth) acrylate, solvent: MIBK, solid content concentration: 20% by mass
・ Hollow silica particles - "Sururia 4320" manufactured by JGC Catalysts and Chemicals, average particle size: 60 nm, solvent: MIBK, solid content concentration: 20% by mass
Photoinitiator - "Omnirad 127" above

<Preparation of composition for forming high refractive index layer>
UV curable resin composition "Riodurus TYZ65-01" (manufactured by Toyochem, acrylic resin, containing zirconium oxide (average particle size 80 nm), photopolymerization initiator, solvent (cyclohexanone, methyl isobutyl ketone, propylene glycol monomethyl ether), solid concentration of 35% by mass), a solvent (MEK / PGM = 1/1) is added so that the solid content concentration is 8.5% by mass (concentration with respect to the entire composition for forming a high refractive index layer), and the high refractive index layer A forming composition was prepared.

<Preparation of hard coat layer>
For each of Examples 1 to 5 and Comparative Example 1, a #4 wire bar was used on a substrate film (Toray's "Lumirror #50-U403", polyethylene terephthalate film, thickness 50 μm) for forming a hard coat layer. The composition was applied. After drying at 80° C. for 3 minutes, an electrodeless (microwave) lamp was used to irradiate ultraviolet light at a light intensity of 80 mJ/cm ² to form a hard coat layer.

<Preparation of high refractive index layer>
For Example 5, the composition for forming a high refractive index layer was applied onto the surface of the hard coat layer using a #4 wire bar, dried at 80°C for 3 minutes, and then subjected to an electrodeless (microwave type ) was irradiated with ultraviolet rays at a light intensity of 150 mJ/cm ² using a lamp to form a high refractive index layer.

<Preparation of low refractive index layer>
A low refractive index layer was formed on the surface of the hard coat layer in Examples 1 to 4 and Comparative Example 1, and on the surface of the high refractive index layer in Example 5. At this time, the composition for forming a low refractive index layer was applied using a #4 wire bar, dried at 80° C. for 60 seconds, and then under a nitrogen atmosphere using an electrodeless (microwave) lamp with a light intensity of 150 mJ. A low refractive index layer was formed by irradiating ultraviolet rays of 1/cm ² .

As described above, an antireflection film was produced. The thicknesses of the hard coat layer, the high refractive index layer, and the low refractive index layer were measured by spectral interferometry using Filmetrics F20 film thickness measurement system, and are shown in Table 1.

<Evaluation method>
(Scratch resistance)
Using a flat abrasion tester ("DAS-400" manufactured by Daiei Kagaku Seiki Seisakusho), steel wool #0000 (manufactured by Nippon Steel Wool Co., Ltd.) fixed to a flat friction element of 20 mm × 20 mm was used to measure the low refractive index of the antireflection film. It was placed on the surface of the rate layer and reciprocated. The stroke length of the test stand was 50 mm, the reciprocation speed of the test stand was 60 reciprocations/minute, and the load was 1.0 kg, and the reciprocation was performed 1500 times. The antireflection film after the test with scratches of 10 mm or more in length was evaluated as having low scratch resistance (×). In addition, those with scratches less than 10 mm in length but no scratches with a length of 10 mm or more were evaluated as having high scratch resistance (◯). A damage of this degree poses no practical problem. Furthermore, those without scratches were evaluated as having very high scratch resistance (⊚).

(Pencil hardness)
The surface of each sample was measured for pencil hardness by the method specified in JIS K 5600-5-4 using a pencil hardness tester (manufactured by Tester Sangyo). The test load was 1 kg, and the test was repeated while changing the hardness of the pencil.

(Luminosity reflectance)
The back surface of the antireflection film (the surface opposite to the low refractive index layer) was roughened with #400 sandpaper, painted with black paint, and measured with an ultraviolet-visible near-infrared spectrophotometer (manufactured by Shimadzu Corporation "UV-3600 ) was used to measure the 5° specular reflectance of the surface of the low refractive index layer, and the measured value was multiplied by the relative luminous efficiency value to calculate the luminous reflectance.

(Haze (Hz), total light transmittance (Tt))
Haze (Hz) and total light transmittance (Tt) of the entire antireflection film were measured by the method of JIS-K7136 using Nippon Denshoku's "Haze Meter NDH7000".

<Evaluation results>
Table 1 below shows the evaluation results of Examples 1 to 5 and Comparative Example 1 together with the component composition of the hard coat layer and the thickness of each layer.

In Comparative Example 1, in which the curable composition constituting the hard coat layer did not contain a polyfunctional secondary thiol, the scratch resistance evaluation result was poor. On the other hand, in Examples 1 to 5, in which the curable composition constituting the hard coat layer contained a polyfunctional secondary thiol, high scratch resistance was obtained. From this, it can be seen that the scratch resistance of the antireflection film is improved by adding a polyfunctional secondary thiol to the curable composition constituting the hard coat layer. In particular, Examples 1, 3, and 5, in which the polyfunctional secondary thiol content exceeds 5% by mass, provide extremely high scratch resistance. Furthermore, in Examples 1 to 5, a pencil hardness of H or more, a luminous reflectance of 2.0% or less, a haze of 1.5 or less, and a total light transmittance of 90% or more were obtained. is sufficiently high as the performance of the antireflection film. The test for evaluation of scratch resistance is performed under stricter conditions than the test in Patent Document 1, and the sample of Comparative Example 1 is also considered to have sufficient scratch resistance according to the standards of Patent Document 1. .

As described above, in an antireflection film having a base film, a hard coat layer formed on the surface of the base film, and an antireflection layer formed on the surface of the hard coat layer, the hard coat By forming the layer from a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound and a polyfunctional secondary thiol, the hard coat layer contributes to provide an antireflection film with excellent scratch resistance. Become.

Although the embodiments of the present invention have been described above, the present invention is by no means limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

10, 20, 30, 40 Antireflection film 12 Base film 14 Low refractive index layer 16 Hard coat layer 17 High refractive index layer 18 Inorganic oxide particles 22 Hollow silica particles 24 Transparent adhesive layer 26 Release film 28 Adhesive layer 32 Protection the film

Claims (7)

A substrate film, a hard coat layer formed on the surface of the substrate film, and an antireflection layer formed on the surface of the hard coat layer,
The hard coat layer is
(meth) acrylate compound,
a polyfunctional secondary thiol;
An antireflection film comprising a cured product of an ionizing radiation-curable composition containing The ionizing radiation curable composition contains, as the (meth)acrylate compound,
A polyfunctional urethane (meth)acrylate compound,
a pentaerythritol (meth)acrylate compound having a hydroxyl value of 200 mgKOH/g or more and 350 mgKOH/g or less;
The antireflection film according to claim 1, comprising: 3. The content of the pentaerythritol (meth)acrylate compound in the ionizing radiation-curable composition is 15% by mass or more and 75% by mass or less with respect to 100% by mass of the solid content of the (meth)acrylate compound. Antireflection film as described. The antireflection film according to any one of claims 1 to 3, wherein the polyfunctional secondary thiol is trifunctional or higher. 5. Any one of claims 1 to 4, wherein the content of the polyfunctional secondary thiol in the ionizing radiation-curable composition is 3% by mass or more and 35% by mass or less with respect to 100% by mass of the solid content. The antireflection film described in . 6. The base film and the antireflection layer according to any one of claims 1 to 5, wherein at least a portion in contact with the hard coat layer is made of a material having a carbon-carbon double bond. anti-reflection film. 7. The antireflection layer according to any one of claims 1 to 6, wherein at least a portion in contact with the hard coat layer is composed of a cured product of an ionizing radiation-curable material containing (meth)acrylate. Antireflection film as described.

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