Heat-shielding adhesive film, heat-shielding window film, and heat-shielding structure

Abstract

Provided are: a heat-shielding adhesive film that can impart excellent heat-shielding performance to a window film and also has excellent antifogging property and durability; and a heat-shielding window film provided with the heat-shielding adhesive film.　The heat-shielding adhesive film of the present invention has a hard coat layer on one surface of a base material layer and an adhesive layer on the other surface thereof. The base material layer has a multilayer structure in which a resin layer 1 containing a thermoplastic resin 1 and a resin layer 2 containing a thermoplastic resin 2 are alternately laminated. The resin layer 1 and the resin layer 2 have different refractive indices, and the water contact angle of the surface of the hard coat layer is 20° or less.

Description

Heat-shielding adhesive film, heat-shielding window film and heat-shielding structure

[0001] The present invention relates to a heat-shielding pressure-sensitive adhesive film, a heat-shielding window film, and a heat-shielding structure.

[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 multilayer film including an infrared-reflecting multilayer film having alternating layers of a first polymer type and a second polymer type, and an infrared-absorbing nanoparticle layer. Such a multilayer film is said to have high visible light transmittance and to be able to substantially block infrared rays.

[0004] Special Publication No. 2008-528313

[0005] However, conventional heat-shielding window films have a problem in that the temperature difference between the inside and outside of the window can cause condensation on the surface of the heat-shielding film, which impairs the heat-shielding performance of the heat-shielding film. Furthermore, when exposed to sunlight for a long period of time, the film deteriorates, posing a durability issue. From this perspective, there has been a need for the development of a window film that not only has excellent heat-shielding properties, but also has excellent anti-fogging properties and durability.

[0006] The present invention has been made in view of the above, and aims to provide a heat-shielding adhesive film that can impart excellent heat-shielding performance to a window film and also has excellent anti-fogging properties and durability, and a heat-shielding window film that includes the heat-shielding adhesive film.

[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 on one side of a predetermined substrate and an adhesive layer on the other side, and by adjusting the water contact angle of the surface of the hard coat layer within a predetermined range, thereby completing the present invention.

[0008] That is, the present invention encompasses, for example, the subject matter described in the following items. Item 1: A heat-shielding pressure-sensitive adhesive film having a hard coat layer on one surface of a substrate layer and a pressure-sensitive adhesive layer on the other surface, the substrate layer having a multilayer structure in which resin layer 1 containing thermoplastic resin 1 and resin layer 2 containing thermoplastic resin 2 are alternately laminated, and resin layer 1 and resin layer 2 have refractive indices different from each other, and the water contact angle of the surface of the hard coat layer is 20° or less. Item 2: The heat-shielding pressure-sensitive adhesive film according to Item 1, in which the hard coat layer or the pressure-sensitive adhesive layer contains an infrared absorbing agent. Item 3: The heat-shielding pressure-sensitive adhesive film according to Item 2, in which the infrared absorbing agent is at least one selected from the group consisting of potassium tungsten oxide, rubidium tungsten oxide, cesium tungsten oxide, thallium tungsten oxide, ITO, and ATO. Item 4: The heat-shielding pressure-sensitive adhesive film according to any one of Items 1 to 3, which is used for window glass. Item 5: A heat-shielding window film comprising the heat-shielding pressure-sensitive adhesive film according to Item 4.

[0009] The heat-shielding pressure-sensitive adhesive film of the present invention can impart excellent heat-shielding performance to a window film, and is also excellent in anti-fogging properties and durability.

[0010]

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

[0011] 1. Heat-shielding adhesive film The heat-shielding adhesive film of the present invention has a hard coat layer on one surface of a base layer and an adhesive layer on the other surface, the base layer has a multilayer structure in which a resin layer 1 containing a thermoplastic resin 1 and a resin layer 2 containing a thermoplastic resin 2 are alternately laminated, the resin layers 1 and 2 having refractive indices different from each other, and the water contact angle of the surface of the hard coat layer is 20° or less.

[0012] The heat-shielding pressure-sensitive adhesive film of the present invention can impart excellent heat-shielding performance to a window film, and also has excellent anti-fogging properties and durability. Therefore, the heat-shielding pressure-sensitive adhesive film 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 heat-shielding pressure-sensitive adhesive film of the present invention, and serves as a member that supports the hard coat layer and the pressure-sensitive adhesive layer.

[0014] As described above, the base layer has a multilayer structure in which resin layer 1 containing thermoplastic resin 1 and resin layer 2 containing thermoplastic resin 2 are alternately laminated. Resin layer 1 and resin layer 2 have different refractive indices. Hereinafter, the refractive index of resin layer 1 is assumed to be greater than the refractive index of resin layer 2.

[0015] By providing the heat-shielding pressure-sensitive adhesive film of the present invention with the base layer, the heat-shielding properties are particularly improved.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The substrate layer has a multilayer structure in which resin layers 1 and 2 are alternately laminated. For example, the substrate layer is formed by laminating a plurality of alternating layers made of resin layers 1 and 2 in the thickness direction. In particular, since the refractive indexes of resin layers 1 and 2 are different, the substrate layer can have the property of being able to selectively reflect light of a specific wavelength.

[0024] In the base material layer, the total number of resin layers 1 and 2 stacked can be set within the range of 500 to 1500 layers, for example.

[0025] The substrate layer can be produced by, for example, a known method, or can be obtained from a commercially available product. Examples of commercially available substrate layer products include Teijin (registered trademark) Tetoron (registered trademark) films 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.

[0026] The thickness of the base 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 200 μm or less, more preferably 188 μm or less, and even more preferably 150 μm or less.

[0027] 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.

[0028] (Hard Coat Layer) The hard coat layer is a layer provided on one surface of the substrate layer.

[0029] 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 them, it is preferable that the hard coat layer is 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 hard coat layer can contain a cured product of an ultraviolet curable acrylic resin.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] Specific examples of monofunctional oligomers having an acrylic polymerizable unsaturated group include ethoxylated o-phenylphenol acrylate, methoxypolyethylene glycol acrylate, and phenoxypolyethylene glycol acrylate.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] As described above, the surface of the hard coat layer has a water contact angle of 20° or less. The surface of the hard coat layer particularly refers to the surface of the hard coat layer opposite the substrate layer, and can mean the exposed surface (the surface exposed to the outside air) when the heat-shielding pressure-sensitive adhesive film of the present invention is attached to a window glass or the like.

[0041] When the water contact angle of the surface of the hard coat layer is 20° or less, the phenomenon of fogging due to condensation is unlikely to occur when the heat-shielding pressure-sensitive adhesive film of the present invention is attached to window glass, etc., i.e., the anti-fogging property is excellent. When the water contact angle of the surface of the hard coat layer exceeds 20°, the desired anti-fogging property cannot be obtained, and visibility is reduced due to condensation, etc.

[0042] The water contact angle of the surface of the hard coat layer is preferably 18° or less, more preferably 15° or less, even more preferably 13° or less, and particularly preferably 10° or less. The lower limit of the water contact angle of the surface of the hard coat layer is not particularly limited, and may be, for example, 0° or more, or 1° or more.

[0043] The method for adjusting the water contact angle of the surface of the hard coat layer to 20° or less is not particularly limited, and various methods can be used to adjust the water contact angle of the surface of the hard coat layer to 20° or less. For example, the water contact angle of the surface of the hard coat layer can be adjusted to 20° or less by a method of adjusting the water contact angle of the surface of the hard coat layer by incorporating inorganic fine particles into the hard coat layer, or by a method of incorporating a surfactant into the hard coat layer.

[0044] The inorganic fine particles are preferably hydrophilic inorganic fine particles, and among them, hydrophilic metal oxide particles can be mentioned. As the hydrophilic metal oxide particles, various metal oxide particles can be mentioned, for example, colloidal silica, alumina sol, titania sol, zirconia sol, etc., and colloidal silica, alumina sol, etc. are more preferred. The hard coat layer can contain one or more types of inorganic fine particles.

[0045] The shape of the inorganic fine particles is not particularly limited, and examples thereof include spherical, irregular, and fibrous shapes. The average particle size of the inorganic fine particles is not particularly limited, and can be, for example, 5 to 500 nm, and preferably 10 to 100 nm. The average particle size of the inorganic fine particles is the average value (median diameter) of the particle size distribution measured by a laser diffraction scattering method. Furthermore, when the inorganic fine particles are fibrous, the minor axis can be 1 to 50 nm, and the major axis can be 500 to 5000 nm. The minor axis is preferably 2 to 10 nm, and the major axis is preferably 1000 to 3000 nm.

[0046] The content of the inorganic fine particles in the hard coat layer is not particularly limited as long as the water contact angle is 20° or less. For example, the content of the inorganic fine particles is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and particularly preferably 5 parts by mass or more, per 100 parts by mass of the total mass of the hard coat layer, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0047] The surfactant may be any of various surfactants, and among these, silicone surfactants are preferably used. Examples of silicone surfactants include polyoxyethylene-methylpolysiloxane copolymers. The hard coat layer may contain one or more surfactants.

[0048] The content of the surfactant in the hard coat layer is not particularly limited as long as the water contact angle is 20° or less. For example, the content of the surfactant is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.4 parts by mass or more, and particularly preferably 0.5 parts by mass or more, per 100 parts by mass of the total mass of the hard coat layer, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

[0049] The hard coat layer may contain additives other than the inorganic fine particles and the surfactant, such as an ultraviolet absorber and an infrared absorber, which will be described later. In particular, the hard coat layer preferably contains an infrared absorber, which will be described later. It is also preferable that the hard coat layer does not contain an ultraviolet absorber, which will be described later.

[0050] In addition to the ultraviolet absorber and the infrared absorber, the hard coat layer may contain other components within a range that does not impair the effects of the present embodiment. Examples of the other components include various components that can be contained in known window films.

[0051] The thickness of the hard coat layer is not particularly limited and can be, for example, 0.1 to 5.0 μm, preferably 0.5 to 4.0 μm, and more preferably 0.9 to 3.0 μm. The thickness of the hard coat layer can be measured using an optical film thickness meter.

[0052] 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. In addition to the ultraviolet curable resin and the ultraviolet polymerization initiator, the hard coat composition can also contain the aforementioned inorganic fine particles to make the water contact angle of the surface 20° or less.

[0053] As will be described later, the hard coat composition contains an ultraviolet absorber or an infrared absorber, and may also contain other additives as necessary.

[0054] (Adhesive Layer) In the film of the present invention, an adhesive layer is formed on the surface of the substrate layer opposite the hard coat layer. 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 glass.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The adhesive layer may contain, for example, an ultraviolet absorber, an infrared absorber, etc., which will be described later. In particular, the adhesive layer preferably contains an ultraviolet absorber, which will be described later. The adhesive layer may also contain other components, as long as the effects of this embodiment are not impaired. Examples of such other components include various components that can be contained in known window films, such as light stabilizers (hindered amine light stabilizers (HALS), etc.), fluorine-based antifouling agents, etc.

[0059] In addition to the ultraviolet absorber and the infrared absorber, the adhesive layer may contain other components within a 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.

[0060] 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.

[0061] The method for forming the adhesive layer on the substrate layer is not particularly limited, and for example, a wide variety of known methods can be used. For example, an adhesive composition containing an adhesive and a crosslinking agent added as needed is applied, and the adhesive layer can be formed by heat treatment or the like under appropriate conditions. As described below, the adhesive composition contains an ultraviolet absorber or an infrared absorber, and may also contain other additives as needed. In particular, it is preferable that the adhesive composition contains an ultraviolet absorber.

[0062] (Ultraviolet absorber) The heat-shielding pressure-sensitive adhesive film of the present invention may contain an ultraviolet absorber. The ultraviolet absorber may be contained in any layer constituting the heat-shielding pressure-sensitive adhesive film of the present invention, and is preferably contained in the hard coat layer and / or the pressure-sensitive adhesive layer, and more preferably contained in the pressure-sensitive adhesive layer.

[0063] The type of ultraviolet absorber is not particularly limited, and for example, a wide variety of known ultraviolet absorbers can be used. Examples of ultraviolet absorbers include a triazine-based ultraviolet absorber (Tinuvin 477) and a benzotriazole-based ultraviolet absorber (Tinuvin 384-2, Tinuvin PS) manufactured by BASF Japan Ltd. By including these ultraviolet absorbers, the heat-shielding pressure-sensitive adhesive film of the present invention has a higher heat-shielding effect and is also likely to have increased durability.

[0064] The content of ultraviolet absorber is also not particularly limited.For example, when ultraviolet absorber is contained in the adhesive layer, the content of ultraviolet absorber is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the total mass of the adhesive layer, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, more preferably 7 parts by mass or less, particularly preferably 5 parts by mass or less.In addition, when ultraviolet absorber is contained in the hard coat layer or the base layer, the content ratio of ultraviolet absorber can be the same range as the content of ultraviolet absorber contained in the adhesive layer.

[0065] The heat-shielding pressure-sensitive adhesive film of the present invention may contain one or more types of ultraviolet absorbers.

[0066] The ultraviolet absorber can be produced by a known method, or can be obtained from a commercial product.

[0067] The method for incorporating an ultraviolet absorber into the hard coat layer or the adhesive layer is not particularly limited. For example, the ultraviolet absorber can be incorporated into the hard coat layer or the adhesive layer by incorporating the ultraviolet absorber into the above-mentioned hard coat composition or adhesive composition.

[0068] (Infrared absorbing agent) The heat-shielding pressure-sensitive adhesive film of the present invention can contain an infrared ray absorbing agent. The infrared absorbing agent may be contained in any layer constituting the heat-shielding pressure-sensitive adhesive film of the present invention, and is preferably contained in the hard coat layer and / or the pressure-sensitive adhesive layer, more preferably contained in the hard coat layer or the pressure-sensitive adhesive layer, and even more preferably contained in the hard coat layer.

[0069] The type of infrared absorbing agent contained in the heat-shielding pressure-sensitive adhesive film of the present invention is not particularly limited, and for example, a wide range of known infrared absorbing agents can be used.

[0070] The infrared absorber may be at least one selected from the group consisting of potassium tungsten oxide, rubidium tungsten oxide, cesium tungsten oxide, thallium tungsten oxide, ITO, and ATO, where ITO means tin-doped indium oxide and ATO means antimony-doped tin oxide.

[0071] Among them, cesium tungsten oxide is more preferable as the infrared absorber. In this case, the heat-shielding pressure-sensitive adhesive film of the present invention has a higher heat-shielding effect and is likely to have higher durability. Cesium tungsten oxide is cesium-doped tungsten oxide, also known as CWO.

[0072] The infrared absorber, such as cesium-doped tungsten oxide, is, for example, particulate. When the infrared absorber is particulate, its average particle size 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, and 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.

[0073] The content of the infrared absorbent is not particularly limited. For example, when the infrared absorbent is contained in the hard coat layer, the content of the infrared absorbent is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, particularly preferably 5 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, per 100 parts by mass of the total mass of the hard coat layer.

[0074] The heat-shielding pressure-sensitive adhesive film of the present invention may contain one or more types of infrared absorbents.

[0075] The infrared absorbent can be produced by a known method, or can be obtained from a commercial product.

[0076] The method for incorporating an infrared absorbent into the hard coat layer or the adhesive layer is not particularly limited. For example, the infrared absorbent can be incorporated into the hard coat layer or the adhesive layer by incorporating the infrared absorbent into the hard coat composition or the adhesive composition described above.

[0077] (Heat-shielding adhesive film) The heat-shielding adhesive film A of the present invention has a hard coat layer on one side of a substrate layer and an adhesive layer on the other side. It is preferable that both of these layers are directly bonded to the substrate layer. That is, it is preferable that no layer exists between the substrate layer and the hard coat layer, and it is also preferable that no layer exists between the substrate layer and the hard coat layer.

[0078] The heat-shielding pressure-sensitive adhesive film of the present invention has the above-mentioned layers, and the water contact angle of the surface of the hard coat layer is 20° or less, thereby imparting excellent heat-shielding performance to the window film and also exhibiting excellent anti-fogging properties and durability. In particular, the heat-shielding pressure-sensitive adhesive film of the present invention also has high transparency, so that when it is attached to window glass, for example, even if a temperature difference occurs between the indoors and outdoors, it is less likely to become cloudy due to condensation, resulting in excellent visibility. In addition, because it has excellent durability, good visibility can be maintained for a long period of time. Therefore, the heat-shielding pressure-sensitive adhesive film of the present invention can be suitably used as a window film with heat-shielding performance (heat-shielding window film).

[0079] The heat-shielding pressure-sensitive adhesive film of the present invention preferably has a total light transmittance of 70% or more. In this case, the heat-shielding pressure-sensitive adhesive film of the present invention has high transparency and is particularly suitable for use as a heat-shielding window film. The heat-shielding pressure-sensitive adhesive film of the present invention more preferably has a total light transmittance of 75% or more, and even more preferably has a total light transmittance of 80% or more. From the viewpoint of transparency, the heat-shielding pressure-sensitive adhesive film of the present invention preferably has a haze of 2% or less.

[0080] The heat-shielding pressure-sensitive adhesive film of the present invention preferably has a solar radiation transmittance of 60% or less, more preferably 50% or less, even more preferably 40% or less, and particularly preferably 30% or less.

[0081] The heat-shielding pressure-sensitive adhesive film of the present invention preferably has a solar reflectance of 1% or more, more preferably 3% or more, even more preferably 5% or more, and particularly preferably 6% or more.

[0082] The heat-shielding pressure-sensitive adhesive film of the present invention can be used for window glass, and is particularly suitable for use as a heat-shielding window film. Such a heat-shielding window film is provided with the heat-shielding pressure-sensitive adhesive film of the present invention, and therefore has excellent anti-fogging properties and durability, as well as excellent heat-shielding performance. It is particularly preferable to use the heat-shielding pressure-sensitive adhesive film of the present invention by attaching it to the window glass of a building or the window glass of a transportation vehicle such as an automobile.

[0083] 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.

[0084] The heat-shielding adhesive 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 encompasses films 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, for example, various materials having releasability, such as silicone.

[0085] The method for producing the film of the present invention is not particularly limited, and for example, any known method can be widely adopted. For example, the heat-shielding pressure-sensitive adhesive film of the present invention can be produced by forming a hard coat layer on one surface of a base layer using the above-mentioned hard coat composition for forming a hard coat layer, and forming a pressure-sensitive adhesive layer on the other surface using the above-mentioned pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer.

[0086] 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.

[0087] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0088] (Production Example 1a: Hard Coat Composition) A hard coat composition 1 was prepared containing 100 parts by mass (based on 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 (solid content equivalent) of hydrophilic colloidal silica having an average particle size of 10 to 15 nm. The colloidal silica was SiO ２ A methyl ethyl ketone dispersion with a concentration of 40% by mass was used.

[0089] (Production Example 1b: Hard Coat Composition) A hard coat composition 2 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, 10 parts by mass (in terms of solid content) of hydrophilic colloidal silica having an average particle size of 10 to 15 nm, and 10 parts by mass of cesium-doped tungsten oxide (CWO) as an infrared absorber having an average particle size of 200 nm. The colloidal silica was SiO ２ A methyl ethyl ketone dispersion with a concentration of 40% by mass was used.

[0090] (Production Example 1c: Hard Coat Composition) A hard coat composition 3 was prepared containing 100 parts by mass (solid content equivalent) of RUA076MG (manufactured by Asia Industries Co., Ltd.) as a hexafunctional urethane acrylate, 0.5 parts by mass of an alkylphenone-based photoinitiator, and 10 parts by mass (solid content equivalent) of hydrophilic alumina sol having a minor axis x major axis of 4 nm x 1,400 nm. ２ O ３ A dispersion with a concentration of 4.5% by weight was used.

[0091] (Production Example 1d: Hard Coat Composition) A hard coat composition 4 was prepared containing 100 parts by mass, in terms of solid content, of RUA076MG (manufactured by Asia Industries Co., Ltd.) as a hexafunctional urethane acrylate, 0.5 parts by mass of an alkylphenone photoinitiator, and 1 part by mass of a polyoxyethylene-methylpolysiloxane copolymer (HLB 14.5) as a silicone surfactant.

[0092] (Preparation Example 1e; Hard Coat Composition) Hard coat composition 5 was prepared containing 100 parts by mass, in terms of solid content, of RUA076MG (manufactured by Asia Industries Co., Ltd.) as a hexafunctional urethane acrylate and 0.5 parts by mass of an alkylphenone photoinitiator.

[0093] (Production Example 1f; Hard Coat Composition) Polyvinyl alcohol "PVA217" manufactured by Kuraray Co., Ltd. was prepared as hard coat composition 6.

[0094] (Production Example 2a: Adhesive Composition) An adhesive composition 1 was prepared 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.

[0095] (Example 1: Heat-shielding adhesive film) A heat-shielding adhesive film was produced by the following procedure. A substrate layer ("PICASUS108QPC4" (registered trademark) manufactured by Toyobo Co., Ltd.) having a multilayer structure in which 1,000 alternating layers formed of a resin layer 1 (refractive index: 1.66) made of polyethylene terephthalate and a resin layer 2 (refractive index: 1.55) made of a copolymer of polyethylene / spiroglycol / cyclohexanecarboxylic acid were stacked was prepared. The hard coat composition 1 prepared in Production Example 1a was applied to one surface of the substrate layer and dried at 80°C for 1 minute. Next, the substrate layer was heated under 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.

[0096] On the other hand, the adhesive composition 1 prepared in Production Example 2a was applied to the silicone-treated surface of a silicone-treated separator sheet (Mitsubishi Plastics, Inc., MRQ#38, 38 μm thick) and dried for 2 minutes in a hot air oven at 100° C. to form an adhesive layer with a thickness of 25 μm. This adhesive layer was superimposed on the surface opposite the hard coat layer of the substrate layer and aged for 7 days to obtain a film with a release layer in which the hard coat layer, substrate layer, adhesive layer, and release layer were laminated in this order.

[0097] Example 2 A film with a release layer was obtained in the same manner as in Example 1, except that the hard coat layer was formed using hard coat composition 2 prepared in Production Example 1b instead of hard coat composition 1.

[0098] Example 3 A film with a release layer was obtained in the same manner as in Example 1, except that the hard coat layer was formed using hard coat composition 3 prepared in Production Example 1c instead of hard coat composition 1.

[0099] Example 4 A film with a release layer was obtained in the same manner as in Example 1, except that the hard coat layer was formed using hard coat composition 4 prepared in Production Example 1d instead of hard coat composition 1.

[0100] Comparative Example 1 A film with a release layer was obtained in the same manner as in Example 1, except that the hard coat layer was formed using hard coat composition 5 prepared in Production Example 1e instead of hard coat composition 1.

[0101] Comparative Example 2 A film with a release layer was obtained in the same manner as in Example 1, except that the hard coat layer was formed using hard coat composition 6 prepared in Production Example 1f instead of hard coat composition 1.

[0102] (Evaluation Method) For the films obtained in each Example and Comparative Example, the water contact angle of the hard coat layer, the total light transmittance, haze, solar transmittance, solar reflectance, heat shading coefficient, anti-fogging property, and durability (haze) of the film were evaluated by the following procedures.

[0103] <Water Contact Angle of Hard Coat Layer> In accordance with JIS R 3257, a dynamic water contact angle tester (1100DAT, manufactured by Fibro) was used to measure the water contact angle 30 seconds after 4 μL of distilled water was dropped onto the surface of the hard coat layer.

[0104] <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.).

[0105] <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.

[0106] <Anti-Fog Properties> The films obtained in the Examples and Comparative Examples were exposed to a water bath at 40°C for 1 minute, and then visually observed for changes in the appearance of the film, and the anti-fogging properties were evaluated according to the following criteria. [Evaluation Criteria] A: No clear changes were observed on the film surface, and visibility through the film was good. B: Blurring was observed in the water film formed on the film surface, but this did not affect visibility through the film. C: Water droplets formed on the film surface, causing fogging and reducing visibility through the film.

[0107] <Durability> The films obtained in the examples and comparative examples were stored in an environment of 60°C and 90% RH for 500 hours, and then the haze of the films was measured using an integrating sphere light transmittance measuring device (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0108] (Evaluation Results) Table 1 shows the layer structure of the film obtained in each Example and Comparative Example, and indicates the additives contained in the hard coat layer and the adhesive layer. Note that a blank in Table 1 means that the additive is not contained.

[0109] Table 2 shows the evaluation results of the films obtained in each Example and Comparative Example, including the water contact angle of the hard coat layer, the total light transmittance of the film, haze, solar transmittance, solar reflectance, heat shading coefficient, anti-fogging property, and durability.

[0110] As can be seen from Table 2, the films obtained in the examples had excellent anti-fogging properties and excellent durability. In Comparative Examples 1 and 2, the water contact angle of the hard coat layer exceeded 20°, so the anti-fogging properties were poor.

[0111]

[0112]

Claims

1. A heat-shielding adhesive film having a hard coat layer on one side of a base layer and an adhesive layer on the other side, wherein the base layer has a multilayer structure in which resin layer 1 containing thermoplastic resin 1 and resin layer 2 containing thermoplastic resin 2 are alternately laminated, and resin layer 1 and resin layer 2 have mutually different refractive indices, and the water contact angle of the surface of the hard coat layer is 20° or less.

2. The heat-shielding adhesive film according to claim 1, wherein the hard coat layer or the adhesive layer contains an infrared absorbing agent.

3. The heat-shielding adhesive film according to claim 2, wherein the infrared absorber is at least one selected from the group consisting of potassium tungsten oxide, rubidium tungsten oxide, cesium tungsten oxide, thallium tungsten oxide, ITO and ATO.

4. The heat-shielding adhesive film according to any one of claims 1 to 3, which is for use on window glass.

5. A heat-shielding window film comprising the heat-shielding adhesive film according to claim 4.

Images