Film with hardcoat layers and heat-shielding window film

Abstract

Provided are: a film with hardcoat layers which is capable of imparting an excellent heat-shielding performance to window films and is highly transparent, and in which the adhesion of the hardcoat layers to a substrate layer is also high; and a heat-shielding window film including the hardcoat film with hardcoat layers.　This film with hardcoat layers comprises a substrate layer provided with a first hardcoat layer and a second hardcoat layer, wherein the first hardcoat layer comprises tin-doped indium oxide and the second hardcoat layer comprises cesium-doped tungsten oxide. A preferred embodiment of this film with hardcoat layers includes the first hardcoat layer provided on one surface of the substrate layer and the second hardcoat layer provided on the other surface thereof.

Description

Hard-coated film and heat-shielding window film

[0001] The present invention relates to a film with a hard coat layer and a heat-shielding window film.

[0002] BACKGROUND ART Window films with heat ray shielding properties have been developed as one of the energy-saving measures for buildings such as buildings and houses, and for transportation such as trains and automobiles. Such window films are required to transmit visible light from sunlight pouring through windows, while blocking heat rays.

[0003] For example, Patent Document 1 discloses a heat-shielding film having a resin substrate film, an adhesive layer, a heat-shielding layer, and a UV hard coat layer, in which the heat-shielding layer contains fine particles of an inorganic near-infrared absorber (antimony-doped tin oxide, antimony-doped zinc oxide, gallium-doped zinc oxide, tin-doped zinc oxide, etc.) It is believed that such a heat-shielding film can enhance the heat-shielding effect and easily impart heat-shielding properties to window glass and the like.

[0004] JP 2013-230613 A

[0005] However, in recent years, there has been a demand for window films with even higher heat-shielding performance, and the technology disclosed in Patent Document 1 sometimes does not provide sufficient heat-shielding performance, leaving room for improvement. In particular, the technology disclosed in Patent Document 1 has the problem that the number of steps required to manufacture the window film increases because the hard coat layer and the heat-shielding layer are provided independently. Also, while it is possible to improve the heat-shielding performance by changing the type and amount of heat-shielding material contained in the hard coat layer, this can sometimes result in a loss of transparency and a deterioration in the adhesion of the hard coat layer to the substrate.

[0006] The present invention has been made in view of the above, and aims to provide a film with a hard coat layer that can impart excellent heat-shielding performance to a window film, has high transparency, and has high adhesion of the hard coat layer to the substrate layer, as well as a heat-shielding window film comprising the hard coat film with a hard coat layer.

[0007] As a result of extensive research into achieving the above object, the inventors have found that the above object can be achieved by providing a hard coat layer containing tin-doped indium oxide and a hard coat layer containing cesium-doped tungsten oxide, and have thus completed the present invention.

[0008] That is, the present invention encompasses, for example, the subject matter described in the following items. Item 1: A hard coat film having a first hard coat layer and a second hard coat layer on a substrate layer, wherein the first hard coat layer contains tin-doped indium oxide, and the second hard coat layer contains cesium-doped tungsten oxide. Item 2: A hard coat film having a first hard coat layer and a second hard coat layer on a substrate layer, wherein the hard coat film has an infrared transmittance of 40% or less at a wavelength of 800 to 1500 nm and an infrared transmittance of 30% or less at a wavelength of 1500 to 2000 nm. Item 3: The hard coat film according to Item 1, wherein the first hard coat layer is on one surface of the substrate layer and the second hard coat layer is on the other surface. Item 4: The hard coat film according to Item 2, wherein the first hard coat layer is on one surface of the substrate layer and the second hard coat layer is on the other surface. Item 5. The hard coat film according to any one of Items 1 to 4, wherein an adhesive layer is formed on either the first hard coat layer or the second hard coat layer. Item 6. The hard coat film according to claim 5, wherein at least one of the base layer and the adhesive layer has an ultraviolet-shielding function. Item 7. The hard coat film according to any one of Items 1 to 6, wherein the first hard coat layer and the second hard coat layer contain a cured product of an ultraviolet-curable acrylic resin. Item 8. The hard coat film according to any one of Items 1 to 4, wherein the hard coat film is used for window glass. Item 9. The hard coat film according to Item 5 or 6, wherein the hard coat film is used for window glass. Item 10. A heat-shielding window film comprising the hard coat film according to Item 8. Item 11. A heat-shielding window film comprising the hard coat film according to Item 9.

[0009] The film with a hard coat layer of the present invention can impart excellent heat-shielding properties to a window film, has high transparency, and also has high adhesion of the hard coat layer to the substrate layer.

[0010]

[0023] In the present specification, the terms "contain" and "comprise" include the concepts of "contain," "comprise," "substantially consist," and "consist only of."

[0011] The hard coat film of the present invention is a hard coat film having a first hard coat layer and a second hard coat layer on a substrate layer, wherein the first hard coat layer contains tin-doped indium oxide and the second hard coat layer contains cesium-doped tungsten oxide. A preferred embodiment of the hard coat film is a hard coat film having a first hard coat layer on one side of a substrate layer and a second hard coat layer on the other side, wherein the first hard coat layer contains tin-doped indium oxide and the second hard coat layer contains cesium-doped tungsten oxide.

[0012] The film with a hard coat layer of the present invention (hereinafter sometimes simply referred to as "the film of the present invention") can impart excellent heat-shielding performance to a window film, has high transparency, and also has high adhesion of the hard coat layer to the substrate layer. Therefore, the film with a hard coat layer of the present invention can be suitably used for a window film having heat-shielding performance (heat-shielding window film).

[0013] (Substrate Layer) The substrate layer is a member that serves as the base of the film of the present invention and serves as a member for supporting the hard coat layer. Therefore, the substrate layer can be formed of an appropriate material taking into consideration, for example, mechanical strength, visible light transmittance, processability, etc.

[0014] Among these, the substrate layer is preferably formed from a material containing a resin, more preferably from a highly transparent resin, and even more preferably from a highly transparent resin film. The substrate layer can be formed from various resins such as polyester resin, acrylic resin, polycarbonate resin, styrene resin, polyolefin resin, hydrogenated cyclic resin, fluororesin, silicone, and urethane resin. Among these, polyester resin is more preferred in terms of excellent transparency and processability, and polyethylene terephthalate (PET) is particularly preferred.

[0015] The substrate layer can have a single-layer structure or a multilayer structure. When the substrate layer has a multilayer structure, each layer can be formed of the same or different resins. One embodiment of a substrate layer having a multilayer structure is a multilayer resin film formed by alternately laminating resin films having different refractive indices. When such a multilayer resin film is used as the substrate layer, the heat-shielding properties of the film of the present invention are particularly improved.

[0016] An example of such a multilayer resin film is a film having a multilayer structure in which resin layer 1 containing thermoplastic resin 1 and resin layer 2 containing thermoplastic resin 2 are alternately laminated. However, resin layer 1 and resin layer 2 have different refractive indices. Hereinafter, it is assumed that the refractive index of resin layer 1 is greater than the refractive index of resin layer 2.

[0017] Examples of the thermoplastic resin 1 include various resins such as polyester resin, acrylic resin, polycarbonate resin, styrene resin, polyolefin resin, hydrogenated cyclic resin, fluororesin, silicone, and urethane resin. Among these, polyester resin is more preferable as the thermoplastic resin 1, and polyethylene terephthalate (PET) is particularly preferable, because of its excellent transparency and processability.

[0018] The resin layer 1 may be made of only the thermoplastic resin 1, or the resin layer 1 may contain a resin other than the thermoplastic resin 1. The resin layer 1 preferably contains 80% by mass or more of the thermoplastic resin 1, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0019] The refractive index of the resin layer 1 is preferably 1.50 or more, more preferably 1.55 or more, even more preferably 1.60 or more, and particularly preferably 1.65 or more. The upper limit of the refractive index of the resin layer 1 is not particularly limited, and is, for example, about 1.8.

[0020] The type of thermoplastic resin 2 is not particularly limited as long as it can provide resin layer 2 with a refractive index lower than that of resin layer 1, and examples thereof include copolymers of polyethylene / spiroglycol / cyclohexanecarboxylic acid, as well as various resins such as polyester resins, acrylic resins, polycarbonate resins, styrene resins, polyolefin resins, hydrogenated cyclic resins, fluororesins, silicones, and urethane resins. Among these, copolymers of polyethylene / spiroglycol / cyclohexanecarboxylic acid are preferred because of their excellent transparency and processability.

[0021] The resin layer 2 may be made of only the thermoplastic resin 2, or the resin layer 2 may contain a resin other than the thermoplastic resin 2. The resin layer 2 preferably contains 80% by mass or more of the thermoplastic resin 2, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0022] The refractive index of the resin layer 2 is preferably 1.65 or less, more preferably 1.60 or less, even more preferably 1.58 or less, and particularly preferably 1.56 or less. The lower limit of the refractive index of the resin layer 1 is not particularly limited, and is, for example, about 1.4.

[0023] The refractive index difference between resin layer 1 and resin layer 2 is, for example, preferably 0.02 or more, more preferably 0.05 or more, and even more preferably 0.1 or more, and is preferably 0.25 or less, preferably 0.2 or less, and even more preferably 0.15 or less.

[0024] The multilayer resin film has a multilayer structure in which resin layer 1 and resin layer 2 are alternately laminated. For example, the multilayer resin film is formed by laminating a plurality of alternating layers made of resin layer 1 and resin layer 2 in the thickness direction. In particular, since resin layer 1 and resin layer 2 have different refractive indices, the multilayer resin film can have the property of being able to selectively reflect light of a specific wavelength.

[0025] In the multilayer resin film, the total number of resin layers 1 and 2 can be set within the range of 500 to 1500 layers, for example.

[0026] The base layer can be produced by, for example, a known method or can be obtained from a commercially available product. In particular, when the base layer is the above-mentioned multilayer resin film, examples of commercially available multilayer resin films that can be used include Teijin (registered trademark) Tetoron (registered trademark) Film MLF, such as MLF-13.0, MLF-16.5, and MLF-19.0 manufactured by Teijin DuPont Films Co., Ltd., and PICASUS (registered trademark) manufactured by Toray Industries, Inc.

[0027] The thickness of the substrate layer can be, for example, 25 μm or more and 250 μm or less, preferably 38 μm or more, more preferably 50 μm or more, and preferably 188 μm or less, more preferably 150 μm or less.

[0028] The substrate layer may contain other components as needed within the range that does not impair the effects of the present embodiment. Examples of such other components include various components that can be contained in known window films, such as ultraviolet absorbers, light stabilizers (e.g., hindered amine light stabilizers (HALS)), and fluorine-based antifouling agents.

[0029] (Hard Coat Layer) The hard coat layer is a layer provided on the substrate layer, for example, on only one side of the substrate layer, or on both sides of the substrate layer. The film of the present invention has at least two types of hard coat layers, one of which is referred to as a "first hard coat layer" and the other as a "second hard coat layer." The first hard coat layer contains tin-doped indium oxide, as described below, and the second hard coat layer contains cesium-doped tungsten oxide, as described below. When a hard coat layer is provided on each side of the substrate layer, for example, a first hard coat layer is provided on one side of the substrate layer and a second hard coat layer is provided on the other side.

[0030] In the following description, the term "hard coat layer" includes both the "first hard coat layer" and the "second hard coat layer."

[0031] When the film of the present invention is provided on a window, the hard coat layer has the property of blocking heat rays and ultraviolet rays from sunlight irradiated from outside the room mainly by reflection, and also blocking far infrared rays emitted from inside the room mainly by reflection.

[0032] The material for forming the hard coat layer is not particularly limited, and for example, a wide range of materials for forming a known hard coat layer can be used. Among these, the hard coat layer is preferably formed from a material containing an ultraviolet-curable resin. That is, the hard coat layer can contain a cured product of an ultraviolet-curable acrylic resin. Therefore, the first hard coat layer and the second hard coat layer can contain a cured product of an ultraviolet-curable acrylic resin.

[0033] Examples of the ultraviolet-curable resin include acrylic resins, silicone resins, urethane resins, olefin resins, and ester resins. From the viewpoint of ease of handling and processing, ultraviolet-curable acrylic resins are preferred. The ultraviolet-curable resins may be used alone or in combination of two or more different types.

[0034] Examples of the ultraviolet-curable acrylic resin include a polymer of a curable composition comprising a monomer or oligomer having an acrylic polymerizable unsaturated group. The monomer or oligomer having an acrylic polymerizable unsaturated group may be either monofunctional or polyfunctional, or may contain both. In order to ensure that the hard coat layer has an appropriate strength, it is preferable that the monomer or oligomer having an acrylic polymerizable unsaturated group is polyfunctional.

[0035] Specific examples of the monofunctional monomer having an acrylic polymerizable unsaturated group include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate.

[0036] Specific examples of monofunctional oligomers having an acrylic polymerizable unsaturated group include ethoxylated o-phenylphenol acrylate, methoxypolyethylene glycol acrylate, and phenoxypolyethylene glycol acrylate.

[0037] On the other hand, examples of polyfunctional acrylic monomers or oligomers having a polymerizable unsaturated group include polyfunctional (meth)acrylic acid esters, and specific examples thereof include bifunctional (meth)acrylates such as dipropylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene oxide-modified neopentyl glycol di(meth)acrylate, modified bisphenol A di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and polyethylene glycol di(meth)acrylate; pentaerythritol tri(meth)acrylate; Examples of the (meth)acrylate include trifunctional (meth)acrylates such as acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxy tri(meth)acrylate, polyether tri(meth)acrylate, and glycerin propoxy tri(meth)acrylate; and tetrafunctional or higher (meth)acrylates such as pentaerythritol tetra(meth)acrylate, pentaerythritol ethoxy tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. These may be used alone or in combination of two or more. In order to ensure the hardness of the hard coat layer, it is preferable to use a tetrafunctional or higher (meth)acrylate.

[0038] Examples of the monomer or oligomer having an acrylic polymerizable unsaturated group include fluorine-containing acrylic resins in which some of the hydrogen atoms are substituted with fluorine atoms. In this case, the scratch resistance and stain resistance of the hard coat layer are likely to be improved.

[0039] In addition to the above, the ultraviolet curable resin is also preferably a urethane-based curable resin composed of a polymer of a urethane acrylate monomer or oligomer. For example, a wide range of known urethane acrylate oligomers can be used as the urethane acrylate oligomer, and specifically, an oligomer in which polyoxyalkylene segments or saturated polyester segments or both are linked via urethane bonds and has acryloyl groups at both ends can be mentioned. For example, the urethane acrylate oligomer can be obtained from a commercially available product.

[0040] When the hard coat layer is formed using an ultraviolet curable resin, an ultraviolet polymerization initiator can be used to cure the ultraviolet curable resin.

[0041] As the ultraviolet polymerization initiator, various known polymerization initiators can be used. Specific examples of the ultraviolet polymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, α-hydroxyacetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyphenyl)-2-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 2-hydroxy-2-methyl-1-phenyl ... Examples of the benzoic acid ester include (hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, propiophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, and p-dimethylamine benzoate.

[0042] These ultraviolet polymerization initiators may be used alone or in combination of two or more. The amount of ultraviolet polymerization initiator added may be, for example, 1 to 10 mass % based on the total mass of the ultraviolet curable resin. The ultraviolet polymerization initiator may be commercially available.

[0043] The method for forming the hard coat layer is not particularly limited, and for example, a known method can be widely adopted. Specifically, a hard coat composition containing an ultraviolet curable resin for forming the hard coat layer and an ultraviolet polymerization initiator is coated on a substrate layer to form a coating film, and the coating film is irradiated with ultraviolet light to form the hard coat layer. As described later, the hard coat composition contains tin-doped indium oxide or cesium-doped tungsten oxide, and may also contain other additives as necessary.

[0044] As described above, the hard coat layer is formed, for example, as a first hard coat layer on one side of the substrate layer and as a second hard coat layer on the other side. The first hard coat layer and the second hard coat layer may both be formed on the same side of the substrate layer, and in this case, either the first hard coat layer or the second hard coat layer may be disposed on the substrate layer side. Preferably, the first hard coat layer is disposed on one side of the substrate, and the second hard coat layer is disposed on the other side of the substrate. In this case, it is preferable that both the first hard coat layer and the second hard coat layer are disposed directly on the substrate layer. It is preferable that the film of the present invention has one layer of each of the first hard coat layer and the second hard coat layer.

[0045] The first hard coat layer contains tin-doped indium oxide, which is commonly known as ITO. The inclusion of ITO in the first hard coat layer can impart excellent heat-shielding properties to the film of the present invention.

[0046] The tin-doped indium oxide is preferably in the form of particles, that is, the first hard coat layer preferably contains tin-doped indium oxide particles.

[0047] It is preferable that the first hard coat layer does not contain metal oxide particles having heat-shielding properties other than tin-doped indium oxide. This further increases the adhesion of the first hard coat layer to the substrate layer, and also makes it easier to improve the heat-shielding properties. It is more preferable that the metal oxide particles contained in the first hard coat layer are only tin-doped indium oxide. Note that the metal oxide particles having heat-shielding properties particularly refer to metal oxide particles having the property of blocking infrared rays.

[0048] The average particle size of the tin-doped indium oxide particles is, for example, 5 to 500 nm, preferably 20 nm or more, more preferably 40 nm or more, even more preferably 50 nm or more, and particularly preferably 60 nm or more, and is preferably 400 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and particularly preferably 150 nm or less. The average particle size of the tin-doped indium oxide particles is the average value (median diameter) of the particle size distribution measured by a laser diffraction scattering method.

[0049] The content of tin-doped indium oxide in the first hard coat layer is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less.

[0050] The method for incorporating tin-doped indium oxide into the first hard coat layer is not particularly limited. For example, the first hard coat layer can be made to incorporate tin-doped indium oxide by incorporating tin-doped indium oxide into the above-mentioned hard coat composition and forming a hard coat layer using the composition.

[0051] Tin-doped indium oxide can be produced by a known method, or can be obtained from a commercial product.

[0052] The second hard coat layer contains cesium-doped tungsten oxide, which is a so-called CWO. The inclusion of such CWO in the second hard coat layer can impart excellent heat-shielding properties to the film of the present invention.

[0053] The cesium-doped tungsten oxide is preferably in the form of particles, that is, the second hard coat layer preferably contains cesium-doped tungsten oxide particles.

[0054] It is preferable that the second hard coat layer does not contain metal oxide particles having heat-shielding properties other than cesium-doped tungsten oxide. This increases the adhesion of the second hard coat layer to the substrate layer and also tends to improve the heat-shielding properties. It is more preferable that the metal oxide particles contained in the second hard coat layer are only cesium-doped tungsten oxide.

[0055] The average particle size of the cesium-doped tungsten oxide particles is, for example, 5 to 500 nm, preferably 20 nm or more, more preferably 50 nm or more, even more preferably 80 nm or more, particularly preferably 100 nm or more, and preferably 400 nm or less, more preferably 350 nm or less, even more preferably 300 nm or less, particularly preferably 250 nm or less. The average particle size of the cesium-doped tungsten oxide particles is the average value (median diameter) of the particle size distribution measured by laser diffraction scattering method.

[0056] The content of the cesium-doped tungsten oxide in the second hard coat layer is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less.

[0057] The method for incorporating cesium-doped tungsten oxide into the second hard coat layer is not particularly limited. For example, the second hard coat layer can be made to incorporate cesium-doped tungsten oxide by incorporating cesium-doped tungsten oxide into the above-mentioned hard coat composition and then forming a hard coat layer using the composition.

[0058] Cesium-doped tungsten oxide can be produced by a known method, or can be obtained as a commercially available product.

[0059] The thickness of the hard coat layer is not particularly limited and can be set within an appropriate range depending on the purpose, etc. For example, the thickness of the hard coat layer can be set to 0.1 to 5.0 μm, preferably 0.5 to 4.0 μm, and more preferably 0.9 to 3.0 μm. The thicknesses of the first hard coat layer and the second hard coat layer may be the same or different. The thickness of the hard coat layer can be measured using an optical film thickness meter.

[0060] The hard coat layer may contain other components as needed within the range that does not impair the effects of this embodiment. Examples of such other components include various components that can be contained in known window films, such as ultraviolet absorbers, light stabilizers (e.g., hindered amine light stabilizers (HALS)), and fluorine-based antifouling agents.

[0061] (Adhesive Layer) In the film of the present invention, it is preferable that an adhesive layer is formed on either the first hard coat layer or the second hard coat layer. That is, the adhesive layer can be provided on either the hard coat layer containing tin-doped indium oxide or the hard coat layer containing cesium-doped tungsten oxide. The adhesive layer may be provided on both the first hard coat layer and the second hard coat layer.

[0062] Such an adhesive layer makes it possible to easily attach and fix the film of the present invention to the surface of, for example, a window pane.

[0063] The adhesive layer is provided on the surface of the hard coat layer opposite the substrate layer. For example, in a film in which a first hard coat layer is provided on one surface of the substrate and a second hard coat layer is provided on the other surface of the substrate, when an adhesive layer is provided on the first hard coat layer, the adhesive layer is provided on the surface opposite the substrate layer of the first hard coat layer, and when an adhesive layer is provided on the second hard coat layer, the adhesive layer is provided on the surface opposite the substrate layer of the second hard coat layer. When an adhesive layer is provided on the first hard coat layer, the adhesive layer may not be provided on the second hard coat layer, and when an adhesive layer is provided on the second hard coat layer, the adhesive layer may not be provided on the first hard coat layer. When both the first hard coat layer and the second hard coat layer are formed on the same surface of the substrate layer, the adhesive layer is provided on the hard coat layer that is farther from the substrate layer.

[0064] The adhesive layer can be formed, for example, from a known adhesive, and adhesive layers provided on known window films can be widely applied to the present invention.

[0065] Examples of adhesives for forming the adhesive layer include adhesives or adhesives generally used for attaching glass, etc. For example, the adhesive layer can be formed using adhesives containing various resins such as acrylic, rubber (natural rubber, polybutadiene, etc.), silicone, urethane, polyvinyl butyral, polyvinyl acetal, and ethylene-vinyl acetate. Among these, from the viewpoint of durability, it is preferable to form the adhesive layer using an adhesive containing at least one of an acrylic resin, a rubber resin, and a silicone resin. Adhesives can also be obtained commercially.

[0066] A preferred adhesive layer contains a polymer having a structure in which an acrylic resin is crosslinked with a crosslinking agent.In this case, the adhesive layer has improved water-adhesion suitability and can also have removability.As the crosslinking agent, for example, a wide range of known crosslinking agents used to form adhesive layers can be mentioned, such as epoxy-based crosslinking agents, isocyanate-based crosslinking agents, etc.

[0067] The thickness of the adhesive layer is not particularly limited, and is, for example, 1 to 100 μm, and preferably 5 to 50 μm. The thickness of the adhesive layer can be measured using a commercially available micrometer.

[0068] The adhesive layer may contain other components as needed within the range that does not impair the effects of the present embodiment. Examples of such other components include various components that can be contained in known window films, such as ultraviolet absorbers, light stabilizers (e.g., hindered amine light stabilizers (HALS)), and fluorine-based antifouling agents.

[0069] The method for forming the adhesive layer on the hard coat layer is not particularly limited, and any known method can be used. For example, the adhesive layer can be formed by applying an adhesive composition containing an adhesive and, if necessary, a crosslinking agent and an ultraviolet absorber, and then performing a heat treatment under appropriate conditions.

[0070] (Film with Hard Coat Layer) The film of the present invention (film with hard coat layer) is a laminate comprising a base layer having a first hard coat layer on one side thereof and a second hard coat layer on the other side thereof, and an adhesive layer is formed on at least one of the first hard coat layer and the second hard coat layer. Such an adhesive layer is formed on the side of the hard coat layer opposite to the base layer.

[0071] The adhesive layer is preferably provided on only one of the hard coat layers, and in this case, the adhesive layer may be provided on either the first hard coat layer or the second hard coat layer.

[0072] It is preferable that no layer is interposed between the hard coat layer and the substrate layer, i.e., the hard coat layer is directly provided on the substrate layer. Therefore, in the film of the present invention in which the first hard coat layer is provided on one side of the substrate and the second hard coat layer is provided on the other side of the substrate, it is preferable that no layer is interposed between the first hard coat layer and the substrate layer, and the first hard coat layer is directly provided on the substrate layer, and it is also preferable that no layer is interposed between the second hard coat layer and the substrate layer, and the second hard coat layer is directly provided on the substrate layer.

[0073] In the film of the present invention, it is preferable that at least one of the base layer and the adhesive layer has an ultraviolet ray shielding function, and therefore, it is preferable that at least one of the base layer and the adhesive layer contains the above-mentioned ultraviolet ray absorber so as to exhibit the ultraviolet ray shielding function.

[0074] The type of ultraviolet absorber is not particularly limited, and a wide variety of known ultraviolet absorbers can be used, including, for example, a triazine-based ultraviolet absorber (Tinuvin 477) and a benzotriazole-based ultraviolet absorber (Tinuvin 384-2, Tinuvin PS) manufactured by BASF Japan Ltd.

[0075] The content of the ultraviolet absorber is not particularly limited, and for example, when the ultraviolet absorber is contained in the adhesive layer, it is preferably 0.1 to 8.0 parts by mass, more preferably 0.5 to 4.0 parts by mass, and particularly preferably 1.0 to 3.0 parts by mass per 100 parts by mass of the total mass of the adhesive layer. When the ultraviolet absorber is contained in the base layer, the content can be in the same range as above.

[0076] In the film of the present invention, of the pair of hard coat layers, the hard coat layer to which the pressure-sensitive adhesive layer is not attached preferably has a water contact angle of 90° or more. In this case, the hard coat layer has improved antifouling properties, and when attached to, for example, a window glass, foreign matter is less likely to adhere to the hard coat layer, high transparency is maintained, and visibility is also improved. There are no particular limitations on the method for adjusting the water contact angle to 90° or more, and examples thereof include a method of incorporating the above-mentioned fluorine-based antifouling agent. There are no particular limitations on the type of fluorine-based antifouling agent, and examples thereof include a wide range of known antifouling agents.

[0077] In the film of the present invention, the water contact angle of the hard coat layer to which the pressure-sensitive adhesive layer is attached is not particularly limited, and by making it 40° or less, for example, the interlayer adhesion is likely to be improved.

[0078] In the film of the present invention, of the pair of hard coat layers, the hard coat layer to which the pressure-sensitive adhesive layer is not attached preferably has a pencil hardness of H or more.

[0079] The film of the present invention preferably has a total light transmittance of 70% or more. In this case, the film of the present invention has high transparency and is particularly suitable for use as a heat-shielding window film. The film of the present invention more preferably has a total light transmittance of 75% or more, further preferably has a total light transmittance of 80% or more, and particularly preferably has a total light transmittance of 85% or more. The film of the present invention has a ＊ It is also preferred that the value is between -3% and 3%.

[0080] The film of the present invention preferably has an infrared transmittance of 40% or less at wavelengths of 800 to 1500 nm. In this case, the film of the present invention tends to have low solar radiation transmittance and high solar radiation reflectance, which tends to improve heat-shielding performance and make it more suitable as a heat-shielding window film.

[0081] The film of the present invention preferably has an infrared transmittance of 30% or less at wavelengths of 1500 to 2000 nm. In this case, the film of the present invention tends to have a low solar radiation transmittance and a high solar radiation reflectance, which tends to improve the heat-shielding performance and make the film more suitable as a heat-shielding window film.

[0082] The film of the present invention preferably has a solar radiation transmittance of 70% or less, more preferably 60% or less, and even more preferably 50% or less. The film of the present invention preferably has a solar radiation reflectance of 5% or more, more preferably 10% or more, and even more preferably 20% or more. From the viewpoint of transparency, the film of the present invention preferably has a haze of 2% or less.

[0083] While ITO has a low infrared cutoff rate for wavelengths of 1500 nm or less, CWO can cut off the same range. However, conventionally, CWO has the risk of reducing the total light transmittance because it also absorbs in the visible light range, and there has also been a risk of coloring the hard coat layer blue. In other words, when a hard coat layer contains ITO and CWO, the infrared cutoff rate (heat-shielding performance) and transparency are in a trade-off relationship, making it difficult to improve the performance of both.

[0084] In contrast, as described above, the film of the present invention has an ITO-containing hard coat layer and a CWO-containing hard coat layer formed independently on the substrate layer, thereby achieving excellent heat-shielding performance and high transparency. Furthermore, by forming an ITO-containing hard coat layer and a CWO-containing hard coat layer independently on the substrate layer, the adhesion of each hard coat layer to the substrate layer can be improved.

[0085] The film of the present invention can impart excellent heat-shielding performance to a window film and has high transparency, so it can be used for window glass, and is particularly suitable for use as a heat-shielding window film. In particular, the film with a hard coat layer of the present invention can be attached to the window glass of a building or the window glass of a transportation vehicle such as an automobile. The film of the present invention can be attached to the window glass, for example, via the adhesive layer. A heat-shielding window film including the film of the present invention has excellent transparency and heat-shielding performance.

[0086] Examples of the window glass include transparent glass for taking sunlight from the outside into buildings, vehicles, ships, etc., and are window glass made of, for example, inorganic glass, transparent organic resin, etc. The shape of the window glass may be flat or curved.

[0087] The film of the present invention can be provided with a release layer on the exposed surface of the adhesive layer as needed. Therefore, the present invention also includes a film with a release layer. By providing a release layer on the exposed surface of the adhesive layer as needed, the adhesive layer can be protected. The release layer can be formed from various materials having releasability, such as silicone.

[0088] The method for producing the film of the present invention is not particularly limited, and for example, a known method can be widely adopted. For example, the film of the present invention can be produced by forming a hard coat layer on one side of a substrate layer using the hard coat composition for forming the first hard coat layer described above, and forming a hard coat layer on the other side using the hard coat composition for forming the first hard coat layer described above.

[0089] The present invention also includes the following hard coat film X. Hard coat film X: A hard coat film having a first hard coat layer and a second hard coat layer on a substrate layer, which has an infrared transmittance of 40% or less at wavelengths of 800 to 1500 nm and an infrared transmittance of 30% or less at wavelengths of 1500 to 2000 nm.

[0090] The types and manufacturing methods of the first and second hard coat layers in the hard coat layer-attached film X are the same as those in the film of the present invention. Therefore, in the hard coat layer-attached film X, it is preferable that the first hard coat layer is provided on one side of the substrate and the second hard coat layer is provided on the other side of the substrate, and it is also preferable that an adhesive layer is formed on either the first hard coat layer or the second hard coat layer.

[0091] In specifying the inventions included in the present disclosure, the components (properties, structures, functions, etc.) described in each embodiment of the present disclosure may be combined in any manner. In other words, the present disclosure includes all subject matter consisting of all combinations of the components that can be combined as described in this specification.

[0092] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0093] (Production Example 1; ITO-containing hard coat composition) A hard coat composition 1 was prepared containing 100 parts by mass, in terms of solid content, of RUA076MG (manufactured by Asia Kogyo Co., Ltd.) as a hexafunctional urethane acrylate, 0.5 parts by mass of an alkylphenone-based photoinitiator, and 10 parts by mass of tin-doped indium oxide (ITO) having an average particle diameter of 120 nm as metal oxide particles having heat-shielding properties.

[0094] (Production Example 2; CWO-containing hard coat composition) Hard coat composition 2 was prepared containing 100 parts by mass, converted into solids, of RUA076MG (manufactured by Asia Industries Co., Ltd.) as a hexafunctional urethane acrylate, 0.5 parts by mass of an alkylphenone-based photoinitiator, 10 parts by mass of cesium-doped tungsten oxide (CWO) having an average particle size of 200 nm as metal oxide particles having heat-shielding properties, and 0.5 parts by mass of Optool DAC-HP (manufactured by Daikin Industries, Ltd.) as a fluorine-based antifouling agent.

[0095] (Production Example 3; Hard Coat Composition Containing CWO and ITO) Hard coat composition 3 was prepared containing 100 parts by mass, converted to solids, of RUA076MG (manufactured by Asia Kogyo Co., Ltd.) as a hexafunctional urethane acrylate, 0.5 parts by mass of an alkylphenone-based photoinitiator, 10 parts by mass of cesium-doped tungsten oxide (CWO) having an average particle size of 200 nm and 10 parts by mass of tin-doped indium oxide (ITO) having an average particle size of 120 nm as metal oxide particles having heat-shielding properties, and 0.5 parts by mass of Optool DAC-HP (manufactured by Daikin Industries, Ltd.) as a fluorine-based antifouling agent.

[0096] (Production Example 4: Adhesive Composition) An adhesive composition containing 100 parts by mass of SK-2094 (manufactured by Soken Chemical & Engineering Co., Ltd.) as an acrylic copolymer, 0.5 parts by mass of E-AX (manufactured by Soken Chemical & Engineering Co., Ltd.) as an epoxy crosslinking agent, and 2 parts by mass of Tinuvin 477 (manufactured by BASF) as a triazine ultraviolet absorber was prepared.

[0097] (Example 1) A polyethylene terephthalate (PET) substrate having a thickness of 100 μm was prepared as a substrate layer. The hard coat composition 2 prepared in Production Example 2 was applied to one surface of the substrate layer and dried at 80° C. for 1 minute. Then, the hard coat composition 2 was irradiated with a high-pressure mercury lamp (illuminance 400 mW / cm ２ ) and the light intensity is 150 mJ / cm ２ A second hard coat layer was formed on one surface of the substrate layer to a thickness of 3 μm by irradiating the substrate with ultraviolet light so that the hard coat layer was irradiated ... ２ ) and the light intensity is 150 mJ / cm ２ By irradiating the other surface of the substrate layer with ultraviolet light so as to form a first hard coat layer with a thickness of 3 μm on the other surface of the substrate layer.

[0098] On the other hand, the adhesive composition prepared in Production Example 4 was applied to the silicone-treated surface of a silicone-treated separator sheet (Mitsubishi Plastics, MRQ#38, 38 μm thick), and dried in a hot air oven at 100 ° C for 2 minutes to form an adhesive layer with a thickness of 25 μm. This adhesive layer was superposed on the second hard coat layer and aged for 7 days to obtain a hard coat film with a release layer. The hard coat film with a release layer is a laminate formed by laminating a first hard coat layer, a substrate layer, a second hard coat layer, an adhesive layer, and a release layer in this order.

[0099] (Example 2) A film with a hard coat layer having a release layer was obtained in the same manner as in Example 1, except that the adhesive layer was superimposed on the first hard coat layer. The film with a hard coat layer having a release layer was a laminate in which the release layer, adhesive layer, first hard coat layer, base layer, and second hard coat layer were laminated in this order.

[0100] Example 3 A film with a hard coat layer and a release layer was obtained in the same manner as in Example 1, except that the substrate layer was changed to a multilayer resin film "PICASUS108QPC4" (registered trademark, manufactured by Toyobo Co., Ltd.). The film with a hard coat layer and a release layer was a laminate in which a first hard coat layer, a substrate layer, a second hard coat layer, an adhesive layer, and a release layer were laminated in this order.

[0101] Example 4 A film with a hard coat layer and a release layer was obtained in the same manner as in Example 2, except that the substrate layer was changed to a multilayer resin film "PICASUS108QPC4" (registered trademark, manufactured by Toyobo Co., Ltd.). The film with a hard coat layer and a release layer was a laminate in which a release layer, an adhesive layer, a first hard coat layer, a substrate layer, and a second hard coat layer were laminated in this order.

[0102] Comparative Example 1 A polyethylene terephthalate (PET) substrate having a thickness of 100 μm was prepared as a substrate layer. The hard coat composition 2 prepared in Production Example 2 was applied to one surface of the substrate layer and dried at 80° C. for 1 minute. Then, the hard coat composition 2 was irradiated with a high-pressure mercury lamp (illuminance 400 mW / cm ２ ) and the light intensity is 150 mJ / cm ２ By irradiating the substrate with ultraviolet light so as to form a second hard coat layer having a thickness of 3 μm on one surface of the substrate layer.

[0103] On the other hand, the adhesive composition prepared in Production Example 4 was applied to the silicone-treated surface of a silicone-treated separator sheet (manufactured by Mitsubishi Plastics, MRQ#38, 38 μm thick), and dried in a hot air oven at 100 ° C for 2 minutes to form an adhesive layer with a thickness of 25 μm. This adhesive layer was superimposed on the substrate layer and aged for 7 days to obtain a film with a hard coat layer and a release layer. This film with a hard coat layer and a release layer is a laminate (i.e., a laminate without a first hard coat layer) in which a second hard coat layer, a substrate layer, an adhesive layer, and a release layer are laminated in this order.

[0104] Comparative Example 2 A polyethylene terephthalate (PET) substrate having a thickness of 100 μm was prepared as a substrate layer. The hard coat composition 1 prepared in Production Example 1 was applied to one surface of the substrate layer and dried at 80° C. for 1 minute. Then, the hard coat composition 1 was irradiated with a high-pressure mercury lamp (illuminance 400 mW / cm ２ ) and the light intensity is 150 mJ / cm ２ By irradiating the substrate with ultraviolet light so as to form a first hard coat layer having a thickness of 3 μm on one surface of the substrate layer.

[0105] On the other hand, the adhesive composition prepared in Production Example 4 was applied to the silicone-treated surface of a silicone-treated separator sheet (Mitsubishi Plastics, MRQ#38, 38 μm thick), and dried in a hot air oven at 100 ° C for 2 minutes to form an adhesive layer with a thickness of 25 μm. This adhesive layer was superimposed on the substrate layer and aged for 7 days to obtain a film with a hard coat layer and a release layer. The film with a hard coat layer and a release layer is a laminate (i.e., a laminate without a second hard coat layer) in which a first hard coat layer, a substrate layer, an adhesive layer, and a release layer are laminated in this order.

[0106] Comparative Example 3 A film with a hard coat layer having a release layer was obtained in the same manner as in Comparative Example 1, except that the first hard coat layer was formed from hard coat composition 3 prepared in Production Example 3. The film with a hard coat layer having a release layer was a laminate in which a hard coat layer, a base layer, an adhesive layer, and a release layer were laminated in this order.

[0107] Comparative Example 4 A polyethylene terephthalate (PET) substrate having a thickness of 100 μm was prepared as a substrate layer. The hard coat composition 3 prepared in Production Example 3 was applied to one surface of the substrate layer and dried at 80° C. for 1 minute. Then, the hard coat composition 3 was irradiated with a high-pressure mercury lamp (illuminance 400 mW / cm ２ ) and the light intensity is 150 mJ / cm ２ By irradiating the substrate with ultraviolet light so as to form a hard coat layer with a thickness of 3 μm on one surface of the substrate layer.

[0108] On the other hand, the adhesive composition prepared in Production Example 4 was applied to the silicone-treated surface of a silicone-treated separator sheet (Mitsubishi Plastics, MRQ#38, 38 μm thick), and dried in a hot air oven at 100 ° C for 2 minutes to form an adhesive layer with a thickness of 25 μm. This adhesive layer was superposed on the hard coat layer and aged for 7 days to obtain a hard coat film with a release layer. The hard coat film with a release layer is a laminate formed by laminating a release layer, an adhesive layer, a hard coat layer, and a substrate layer in this order.

[0109] (Evaluation Method) The total light transmittance, haze, solar radiation transmittance, solar radiation reflectance, heat-shielding coefficient, and hard coat layer adhesion of the films obtained in each of the Examples and Comparative Examples were evaluated by the following procedures.

[0110] <Total Light Transmittance and Haze> The films obtained in the Examples and Comparative Examples were cut into 50 mm x 50 mm pieces, the release layer was peeled off, and the pieces were attached to slide glasses (S9112, manufactured by Matsunami Glass Co., Ltd.) to prepare measurement samples. The total light transmittance and haze were measured using an integrating sphere light transmittance measuring device (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0111] <Solar transmittance, solar reflectance, and heat shading coefficient> The films obtained in the examples and comparative examples were cut into 50 mm x 50 mm pieces, the release layer was removed, and the pieces were attached to slide glass (S9112, manufactured by Matsunami Glass Co., Ltd.) to prepare measurement samples. Measurements were performed using a spectrophotometer (U-4100, manufactured by Hitachi, Ltd.) in the wavelength range of 300 to 2500 nm, and the solar transmittance, solar reflectance, and heat shading coefficient were measured in accordance with JIS S3107:2013.

[0112] <Hard Coat Layer Adhesion> The adhesion of the hard coat layer (each of the first and second hard coat layers in the Examples) to the substrate was evaluated by the cross-cut method in accordance with JIS K 5600-5-6 and according to the following criteria. Note that in Comparative Examples 1 to 4, the hard coat layer was provided on only one side of the substrate, so: [Evaluation Criteria] A: No peeling of the hard coat layer. B: Partial peeling of the hard coat layer. C: Complete peeling of the hard coat layer.

[0113] Table 1 shows the layer structure and evaluation results of the hard-coated films obtained in each example and comparative example.In addition, in the column of the position of the adhesive layer in Table 1, "first side" means that the adhesive layer is bonded to the first hard-coat layer side, "second side" means that the adhesive layer is bonded to the second hard-coat layer side, and "substrate side" means that the adhesive layer is bonded directly to the substrate.In addition, "hard-coat layer side" in Comparative Example 4 means that the adhesive layer is bonded to the hard-coat layer.

[0114] As can be seen from Table 1, the hard coat layer films obtained in the examples have excellent heat-shielding performance and high transparency, since the hard coat layer on one side of the substrate layer contains tin-doped indium oxide (ITO) and the other hard coat layer contains cesium-doped tungsten oxide (CWO). Furthermore, it was found that the hard coat layer films obtained in the examples also have high adhesion to the substrate layer for both hard coat layers. On the other hand, the films obtained in Comparative Examples 1 and 2 had high adhesion of the hard coat layer to the substrate layer, but poor heat-shielding performance, and the films obtained in Comparative Examples 3 and 4 had low adhesion of the hard coat layer to the substrate layer.

[0115]

Claims

1. A film with a hard coat layer, comprising a base layer and a first hard coat layer and a second hard coat layer, wherein the first hard coat layer contains tin-doped indium oxide, and the second hard coat layer contains cesium-doped tungsten oxide.

2. A hard-coat film having a first hard-coat layer and a second hard-coat layer on a substrate layer, wherein the hard-coat film has an infrared transmittance of 40% or less at wavelengths of 800 to 1500 nm and an infrared transmittance of 30% or less at wavelengths of 1500 to 2000 nm.

3. The film with a hard coat layer according to claim 1, wherein the first hard coat layer is provided on one surface of the substrate layer, and the second hard coat layer is provided on the other surface of the substrate layer.

4. The film with a hard coat layer according to claim 2, wherein the first hard coat layer is provided on one surface of the substrate layer, and the second hard coat layer is provided on the other surface of the substrate layer.

5. The film with a hard coat layer according to any one of claims 1 to 4, wherein an adhesive layer is formed on either the first hard coat layer or the second hard coat layer.

6. The film with a hard coat layer according to claim 5, wherein at least one of the base layer and the adhesive layer has an ultraviolet ray blocking function.

7. The film with a hard coat layer according to any one of claims 1 to 4, wherein the first hard coat layer and the second hard coat layer contain a cured product of an ultraviolet-curable acrylic resin.

8. The film with a hard coat layer according to any one of claims 1 to 4, which is for use on window glass.

9. The film with a hard coat layer according to claim 5, which is for use on window glass.

10. A heat-shielding window film comprising the film with a hard coat layer according to claim 8.

11. A heat-shielding window film comprising the film with a hard coat layer according to claim 9.

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