Window film

Abstract

To provide a window film which effectively suppresses crimes caused by entry from a window, and improves crime prevention effects.SOLUTION: A window film includes: a laminate including a first base material which is composed of a material containing an aluminum vapor deposition film and polyethylene terephthalate and is arranged on a first surface side that is one surface of the aluminum vapor deposition film, and a second base material which is composed of a material containing polyethylene terephthalate and is arranged on a second surface side that is a surface opposite to the first surface of the aluminum vapor deposition film; and an adhesive layer for sticking which is arranged on a surface side opposite to a surface facing the aluminum vapor deposition film of the second base material and is stuck to an adherend. The aluminum vapor deposition film is preferably provided on the surface of the first base material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to window films. [Background technology]

[0002] Window films are adhesive films that are applied to the window glass of vehicles such as automobiles, ships, and trains, as well as buildings such as houses, apartment buildings, and office buildings. They are widely used for blocking ultraviolet and / or infrared rays in sunlight, protecting privacy, preventing crime, preventing glass from shattering, and for decoration.

[0003] Recently, crimes such as robbery and burglary have been on the rise, leading to a heightened awareness of crime prevention. Burglars and other criminals often break into buildings by breaking window glass. To prevent such intrusions through windows, security window films have been launched onto the market. By applying security window film to windows, the destruction and penetration of glass openings is significantly delayed, dissuading intruders from attempting to break in, thereby providing security for buildings.

[0004] For example, a security window film has been proposed in which the overall thickness of the security window film is increased by increasing the number of laminated films, thereby improving security performance such as tear strength and tensile strength (for example, Patent Document 1).

[0005] However, simply increasing the overall thickness of security window film and improving its strength has limited effectiveness in dissuading intruders from breaking in by buying them time, leaving room for improvement in security effectiveness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-126953 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a window film that effectively prevents crimes committed through windows and improves crime prevention effects. [Means for solving the problem]

[0008] These objects can be achieved by the present invention as set forth in (1) to (6) below. (1) A laminate including an aluminum vapor-deposited film, a first substrate made of a material containing polyethylene terephthalate and disposed on a first surface side of the aluminum vapor-deposited film, and a second substrate made of a material containing polyethylene terephthalate and disposed on a second surface side of the aluminum vapor-deposited film, the second surface side being the surface opposite to the first surface; A window film characterized by having an adhesive layer for adhering to an adherend, arranged on the side of the second substrate opposite the side facing the aluminum vapor deposition film.

[0009] (2) The window film according to (1), wherein the aluminum vapor deposition film is provided on the surface of the first substrate.

[0010] (3) The window film according to (1) or (2) above, wherein the laminate has a bonding adhesive layer that bonds the aluminum vapor deposition film and the second substrate.

[0011] (4) The window film according to (3) above, wherein the polymer serving as the adhesive constituting the adhesive layer for bonding has a content of a monomer containing an acidic group of 0.5% by mass or less.

[0012] (5) The window film according to any one of (1) to (4) above, wherein the laminate comprises three to five substrates made of a material containing polyethylene terephthalate.

[0013] (6) A window film according to any one of (1) to (5) above, further comprising a hard coat layer made of a material containing a (meth)acrylate resin on the surface of the laminate opposite to the surface on which the adhesive layer for application is disposed. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a window film that effectively prevents crimes committed through windows and has improved crime prevention effects. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing a first embodiment of a window film of the present invention. [Figure 2] FIG. 3 is a cross-sectional view showing a second embodiment of the window film of the present invention. [Figure 3] FIG. 2 is a cross-sectional view showing the structure of the window film produced in Comparative Example 1. [Figure 4] FIG. 2 is a cross-sectional view showing the structure of a window film produced in Comparative Example 2. [Figure 5] FIG. 1 is a cross-sectional view showing the structure of a window film produced in Comparative Example 3. [Figure 6] FIG. 10 is a cross-sectional view showing the structure of the window film produced in Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will be described in detail below. [1] Window film [1-1] First embodiment FIG. 1 is a cross-sectional view showing a first embodiment of the window film of the present invention.

[0017] As shown in Figure 1, the window film 1 comprises a laminate 10 including an aluminum vapor-deposited film 11, a first substrate 12 made of a material containing polyethylene terephthalate and arranged on one side (first surface) of the aluminum vapor-deposited film 11, and a second substrate 14 made of a material containing polyethylene terephthalate and arranged on the second side (second surface) of the aluminum vapor-deposited film 11 opposite the first surface; and an adhesive layer 2 for adhering to an adherend, arranged on the side of the second substrate 14 opposite the side facing the aluminum vapor-deposited film 11.

[0018] Glass generally has the property of breaking when subjected to impact, but when the window film 1 having multiple substrates is attached, it takes time for the window film 1 to break.

[0019] Therefore, when window film 1 is applied to a window, even if a burglar or other intruder applies impact to break the window glass, and the glass breaks, window film 1 does not easily break, making it impossible to drill a hole for entry, such as a hole to reach in to unlock a window crescent lock, or it would take a long time to drill a hole for entry. This discourages intruders from attempting to break in, improving crime prevention.

[0020] In this specification, the term "intruder" refers collectively to a person who commits an act of trespassing into a building (for example, breaking a window) and a person who approaches the building with the intention of committing such an act.

[0021] Additionally, because the window film 1 is provided with the aluminum vapor deposition film 11, the aluminum vapor deposition film 11 functions as a mirror, and an intruder attempting to break the window glass will be reflected in the window film 1. This makes the intruder aware that they may be seen by passersby, and in particular that their image or face may be seen reflected in the window film 1, and may make the intruder feel guilty, thereby discouraging them from breaking the glass and enhancing the crime prevention effect.

[0022] In this way, the window film 1 of the present invention can provide a higher crime prevention effect through the synergistic effect of making the film itself less likely to break, thereby making it physically less likely to break, and the psychological effect of its function as a mirror.

[0023] [1-1-1] Laminate As described above, in the present invention, the laminate may comprise an aluminum vapor-deposited film, a first substrate made of a material containing polyethylene terephthalate and arranged on a first surface, which is one side of the aluminum vapor-deposited film, and a second substrate made of a material containing polyethylene terephthalate and arranged on a second surface, which is the surface opposite to the first surface, of the aluminum vapor-deposited film. In this embodiment, however, the laminate 10 comprises an aluminum vapor-deposited film 11, a first substrate 12 made of a material containing polyethylene terephthalate and arranged on a first surface, which is one side of the aluminum vapor-deposited film 11, a second substrate 14 made of a material containing polyethylene terephthalate and arranged on a second surface, which is the surface opposite to the first surface of the aluminum vapor-deposited film 11, and a third substrate 16 made of a material containing polyethylene terephthalate and arranged on the surface of the first substrate 12 opposite to the surface on which the aluminum vapor-deposited film 11 is provided. In other words, in this embodiment, the laminate 10 includes three substrates, namely, a first substrate 12, a second substrate 14, and a third substrate 16, as the plurality of substrates.

[0024] In the following description, a film made of a material containing polyethylene terephthalate as a base material may be referred to as a "PET film."

[0025] As described above, in this embodiment, the laminate 10 includes three base materials, the first base material 12, the second base material 14, and the third base material 16, as the plurality of base materials.

[0026] Thus, it is preferable that the laminate 10 includes three or more base materials. This allows the window film 1 to have better security performance such as elongation and tensile strength.

[0027] On the other hand, if the number of substrates is too large, the productivity of the window film 1 decreases and the manufacturing costs increase, and depending on the thickness of the substrates, the overall thickness of the window film 1 may become thick, making it difficult to wind it onto a roll during manufacturing, resulting in reduced processability, or the film may become too hard during use, making it difficult to handle and install, etc. Therefore, it is preferable that the number of substrates included in the laminate 10 is 5 or less.

[0028] Therefore, by having three to five substrates in the thickness direction of the laminate 10, the productivity of the window film 1 can be increased and manufacturing costs can be reduced, while the security performance of the window film 1 can be achieved at a high level along with ease of processing and installation.

[0029] In the following explanation, the illustrated configuration in which the laminate 10 has three substrates (PET films) will be mainly described, but the present invention is not limited to this, and the number of substrates (PET films) provided in the laminate 10 may be two, or four or more.

[0030] [1-1-1-1] Base material (PET film) The multiple substrates that make up the laminate 10, namely, the first substrate 12, the second substrate 14, and the third substrate 16, are present on the substrate after the window film 1 is attached to the substrate, and are the parts that substantially contribute to the security performance of the window film 1.

[0031] Each of the multiple base materials constituting the laminate 10 is made of a material containing polyethylene terephthalate, and is preferably made mainly of polyethylene terephthalate.

[0032] This further improves the crime prevention performance of the window film 1. In addition, the window film 1 has good handleability, improving the workability of attaching the window film 1 to an object to be adhered.

[0033] In this specification, the term "mainly" refers to the part of interest that has the highest content.

[0034] In particular, the content of polyethylene terephthalate in each of the multiple base materials constituting the laminate 10 is preferably 90% by mass or more, and more preferably 95% by mass or more.

[0035] It is preferable that each of the multiple substrates constituting the laminate 10 is biaxially stretched, which gives the multiple substrates constituting the laminate 10 high tensile strength and improves the crime prevention performance of the window film 1.

[0036] The substrate constituting the laminate 10 may be, for example, a PET film produced by producing an unstretched resin film by a known method such as T-die extrusion molding, and then using a known method such as sequential biaxial stretching or simultaneous biaxial stretching. Note that the substrate constituting the laminate 10 may also be a uniaxially stretched one.

[0037] The thickness of the first base material 12 constituting the laminate 10 is preferably 12 μm or more and 100 μm or less, more preferably 25 μm or more and 75 μm or less, and even more preferably 35 μm or more and 60 μm or less.

[0038] The thickness of each of the second substrate 14 and the third substrate 16 constituting the laminate 10 is preferably 50 μm or more and 125 μm or less, more preferably 75 μm or more and 115 μm or less, and even more preferably 90 μm or more and 110 μm or less.

[0039] If the thickness of the substrates constituting the laminate 10 satisfies the above-mentioned conditions, the ease of handling of each substrate during the production of the laminate 10 and the window film 1 can be improved, and also, for example, when the window film 1 is attached to an adherend by wet lamination, the workability of removing the application liquid after wet lamination can be improved. Furthermore, if each substrate constituting the laminate 10 is too thin, it is necessary to increase the number of bonding pressure-sensitive adhesive layers to ensure the overall thickness of the laminate 10, which can make it difficult to remove the application liquid with a squeegee or the like after wet lamination of the window film 1; however, if the thickness of the substrates constituting the laminate 10 satisfies the above-mentioned conditions, the occurrence of such problems can be more suitably prevented.

[0040] The total thickness of all the substrates (first substrate 12, second substrate 14, and third substrate 16) that make up laminate 10 is preferably 100 μm or more and 500 μm or less, more preferably 150 μm or more and 400 μm or less, and even more preferably 200 μm or more and 260 μm or less.

[0041] This makes it possible to increase the productivity of the window film 1 and reduce manufacturing costs, while simultaneously achieving high levels of security performance, ease of processing, and ease of application of the window film 1.

[0042] The multiple substrates constituting the laminate 10 may have different conditions (e.g., thickness, composition of constituent materials, weight average molecular weight of polyethylene terephthalate, etc.), but it is preferable that the second substrate 14 and the third substrate 16 have the same conditions.

[0043] [1-1-1-2] Aluminum vapor deposition film The laminate 10 and the window film 1 are provided with an aluminum vapor deposition film 11 . The aluminum vapor deposition film 11 has high light reflectance and functions as a mirror.

[0044] In particular, by forming a vapor-deposited film, it is possible to form a film that transmits visible light more than aluminum foil or the like.

[0045] Furthermore, because the aluminum vapor-deposited film 11 is highly flexible, even if the window film 1 is rolled or bent during transportation or application, the aluminum vapor-deposited film 11 is prevented from wrinkling. This prevents deterioration in the overall appearance of the window film 1 and deterioration in the mirror function of the aluminum vapor-deposited film 11, and also makes application easier.

[0046] The aluminum vapor-deposited film 11 may be disposed between the first substrate 12 and the second substrate 14, but in the window film 1 shown in the figure, the aluminum vapor-deposited film 11 is provided on the surface of the first substrate 12. In other words, in the illustrated configuration, the aluminum vapor-deposited film 11 is provided on the surface of the first substrate 12 by a vapor deposition method.

[0047] This allows the window film 1 to function more effectively as a mirror when viewed from the indoor side when attached to the indoor side of a windowpane, even if the thickness of the aluminum vapor-deposited film 11 is relatively thin. This therefore further enhances the crime prevention effect of the window film 1 and is also preferable from the viewpoint of reducing the manufacturing costs of the window film 1.

[0048] The thickness of the aluminum vapor deposition film 11 is not particularly limited, but is set so that the visible light transmittance is 1% or more and 50% or less, and the visible light reflectance is 20% or more and 80% or less, and is preferably 1 nm or more and 1000 nm or less, more preferably 5 nm or more and 500 nm or less, and even more preferably 10 nm or more and 100 nm or less. This makes it possible to make the above-mentioned effects more pronounced.

[0049] [1-1-1-3] Bonding adhesive layer The laminate 10 has a bonding pressure-sensitive adhesive layer that functions to bond adjacent substrates together.

[0050] In the window film 1 shown in Figure 1, the laminate 10 has, as an adhesive layer, an adhesive layer (first adhesive layer 13) that bonds the aluminum vapor deposition film 11 provided on the surface of the first substrate 12 to the second substrate 14, and further has, on the surface of the first substrate 12 opposite to the surface on which the aluminum vapor deposition film 11 is provided, an adhesive layer (second adhesive layer 15) that bonds the first substrate 12 to the third substrate 16.

[0051] The adhesive layers (first adhesive layer 13 and second adhesive layer 15) constituting the laminate 10 can be made of adhesives commonly used in the field of window films 1. Examples of such adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, and polyurethane adhesives. Among these, acrylic adhesives are preferred from the viewpoint of weather resistance. These adhesives may be emulsion-type, solvent-type, or solventless type.

[0052] The weight average molecular weight of the pressure-sensitive adhesive is preferably 300,000 or more and 2,000,000 or less, and more preferably 500,000 or more and 1,500,000 or less.

[0053] The "weight average molecular weight" herein is a value measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0054] [1-1-1-3-1] Acrylic adhesive Examples of acrylic adhesives include (meth)acrylic acid ester copolymers.

[0055] Examples of (meth)acrylic acid ester copolymers include copolymers of a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 20 carbon atoms, a monomer containing a functional group having active hydrogen, and other optionally used monomers.

[0056] In this specification, the term "(meth)acrylic acid" is a concept that includes both "acrylic acid" and "methacrylic acid."

[0057] Examples of (meth)acrylic acid alkyl esters having an alkyl group with 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate, and one or more selected from these may be used in combination.

[0058] Examples of monomers containing a functional group having active hydrogen include hydroxyl group-containing monomers such as (meth)acrylic acid hydroxyalkyl esters, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; amide group-containing monomers, such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylol acrylamide, and N-methylol methacrylamide; monoalkylaminoalkyl (meth)acrylates, such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate; and carboxylic acids having an ethylenically unsaturated bond, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

[0059] Examples of the other monomer that may be optionally used include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene-based monomers such as styrene and α-methylstyrene; diene-based monomers such as butadiene, isoprene, and chloroprene; nitrile-based monomers such as acrylonitrile and methacrylonitrile; and N,N-dialkyl-substituted acrylamides such as N,N-dimethylacrylamide and N,N-dimethylmethacrylamide. One or more selected from these may be used in combination.

[0060] The copolymerization form of the (meth)acrylic acid ester copolymer is not particularly limited, and may be any of a random copolymer, a block copolymer, and a graft copolymer.

[0061] In addition, if the adhesive layer for bonding (first adhesive layer 13) that contacts the aluminum vapor deposition film 11 contains an acidic group, the acidic group may react with the aluminum vapor deposition film 11, causing the adhesive for bonding to turn yellow.

[0062] Therefore, in the adhesive layer for bonding (first adhesive layer 13) that contacts the aluminum vapor deposition film 11, the polymer serving as the adhesive that constitutes the adhesive layer for bonding preferably has a content of monomers containing acidic groups of 0.5 mass % or less, more preferably 0.3 mass % or less, and even more preferably 0.2 mass % or less.

[0063] This makes it possible to more effectively prevent the adhesive for bonding that is in contact with the aluminum vapor-deposited film 11 from yellowing.

[0064] In addition, in the adhesive constituting the adhesive layer for bonding, the content of acid components other than the constituent monomers of the polymer is preferably 0.5 mass % or less, more preferably 0.3 mass % or less, and even more preferably 0.2 mass % or less.

[0065] This effectively prevents the aluminum vapor deposition film 11 from yellowing due to the acid component.

[0066] Examples of such acid components other than the constituent monomers of the polymer include acidic free monomers that were not used in the polymerization.

[0067] [1-1-1-3-2] Silane coupling agent The adhesive layers (first adhesive layer 13 and second adhesive layer 15) constituting the laminate 10 are preferably formed using a material containing an acrylic adhesive and a silane coupling agent.

[0068] This allows the window film 1 to maintain its adhesive strength more suitably even when it is placed in a humid environment while attached to an adherend.

[0069] The silane coupling agent may be any compound that contains a silicon atom and has two or more different reactive groups in the molecule.

[0070] Examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; and amino group-containing silicon compounds such as 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, 1,6-bis(trimethoxysilyl)hexane, and condensates of at least one of these with alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. One or a combination of two or more selected from these can be used.

[0071] The content of the silane coupling agent in the material, i.e., the material used to form the bonding adhesive layer (first adhesive layer 13 and second adhesive layer 15), is preferably 0.005 parts by mass or more and 7.0 parts by mass or less, more preferably 0.05 parts by mass or more and 5.0 parts by mass or less, and even more preferably 0.1 parts by mass or more and 3.0 parts by mass or less, per 100 parts by mass of the acrylic adhesive.

[0072] This makes it possible to more suitably maintain the adhesive strength of the window film 1, particularly when the window film 1 is placed in a humid environment while attached to an adherend.

[0073] [1-1-1-3-3] Other ingredients The adhesive layers (first adhesive layer 13 and second adhesive layer 15) constituting laminate 10 may contain components other than those described above. Hereinafter, in this section, such components will be referred to as "other components."

[0074] Examples of other components include ultraviolet absorbers, tackifiers, fillers, softeners, antioxidants, light stabilizers, crosslinkers, colorants, modifiers, rust inhibitors, flame retardants, hydrolysis inhibitors, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, antistatic agents, polymerization inhibitors, catalysts, leveling agents, thickeners, dispersants, and antifoaming agents.

[0075] However, the content of other components in the bonding adhesive layers (first adhesive layer 13 and second adhesive layer 15) that make up laminate 10 is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0076] [1-1-1-3-4] Other conditions The pressure-sensitive adhesive may be crosslinked. The crosslinking agent used for the crosslinking treatment is not particularly limited, and examples thereof include polyisocyanate compounds, epoxy compounds, melamine resins, urea resins, dialdehydes, methylol polymers, metal chelate compounds, metal alkoxides, and metal salts, and one or more selected from these may be used in combination.

[0077] The amount of crosslinking agent used varies depending on the type, etc., but is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the acrylic adhesive.

[0078] The thickness of each of the bonding adhesive layers (first adhesive layer 13 and second adhesive layer 15) constituting laminate 10 is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less.

[0079] Each adhesive layer (first adhesive layer 13 and second adhesive layer 15) constituting laminate 10 may have different conditions (e.g., thickness, composition, etc.), but it is preferable that they have the same conditions.

[0080] [1-1-2]Adhesive layer for pasting The adhesive layer 2 for adhesion is an adhesive layer for adhering to an adherend, and in the illustrated configuration, is arranged on the side opposite to the side facing the aluminum vapor deposition film 11 of the second substrate 14.

[0081] [1-1-2-1] Adhesive The adhesive constituting the adhesive layer for attachment 2 can be the same as that explained in the above [1-1-1-3] adhesive layer for bonding.

[0082] The adhesive contained in the bonding adhesive layer (first adhesive layer 13 and second adhesive layer 15) that constitutes the laminate 10 and the adhesive contained in the attachment adhesive layer 2 may be of different conditions.

[0083] [1-1-2-2] UV absorbers The window film 1 may be attached to the indoor side of the window glass or to the outdoor side of the window glass, but it is preferable that it be attached to the indoor side of the window glass, from the viewpoint of further enhancing the crime prevention effect of the window film 1.

[0084] When the window film 1 is to be attached to the interior side of a windowpane, the adhesive layer 2 for attachment is disposed on the most exterior side when the window film 1 is attached to the windowpane.

[0085] Therefore, it is preferable that the adhesive layer 2 for application further contains an ultraviolet absorber. This allows the adhesive layer 2 for application to suitably absorb ultraviolet light.

[0086] Examples of the ultraviolet absorber include 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-amyl-5'-isobutylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-isobutyl-5'-methylphenyl)-5-chlorobenzotriazole, and 2-(2'-hydroxy-3'-isobutyl-5'-methylphenyl)-5-chlorobenzotriazole. 2'-Hydroxyphenyl-5-chlorobenzotriazole-based ultraviolet absorbers such as 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 2,2'-Dihydroxybenzophenone UV absorbers such as ',4,4'-tetrahydroxybenzophenone; 2-hydroxybenzophenone UV absorbers such as 2-hydroxy-4-methoxybenzophenone and 2,4-dihydroxybenzophenone; salicylic acid ester UV absorbers such as phenyl salicylate and 4-tert-butyl-phenyl-salicylate; 2-ethyl-hexyl-2-cyano-3,3-diphenylacrylate, ethyl-2-cyano-3,3-diphenylacrylate, octyl-2-cyano cyanoacrylate-based ultraviolet absorbers such as 3,3-diphenylacrylate; triazine-based ultraviolet absorbers such as 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl, 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3-5-triazine, 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine, and tris(hydroxyphenyl)triazine;Examples include reactive ultraviolet absorbers in which an acryloyl group or a methacryloyl group is introduced into a benzotriazole skeleton, and one or more selected from these may be used in combination.

[0087] The content of the ultraviolet absorber in the adhesive layer 2 is preferably 0.5 parts by mass or more and 20 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, per 100 parts by mass of the solid content in the adhesive layer 2.

[0088] [1-1-2-3] Other ingredients The adhesive layer 2 for application may contain components other than those mentioned above. Hereinafter, in this section, such components will be referred to as "other components".

[0089] Examples of other components include tackifiers, fillers, softeners, antioxidants, light stabilizers, crosslinkers, colorants, modifiers, rust inhibitors, flame retardants, hydrolysis inhibitors, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, antistatic agents, polymerization inhibitors, catalysts, leveling agents, thickeners, dispersants, and antifoaming agents.

[0090] The content of other components in the adhesive layer 2 for adhesion is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0091] [1-1-2-4] Other conditions The thickness of the adhesive layer 2 for application is not particularly limited, but is preferably from 1 μm to 100 μm, more preferably from 5 μm to 80 μm, and even more preferably from 10 μm to 60 μm.

[0092] This can improve the durability of the window film 1, and also improve the ease of handling of the window film 1, making it easier to apply (stick) to an adherend. Also, the adhesive strength to an adherend is improved.

[0093] [1-1-3] Hard coat layer The window film 1 shown in the figure further comprises a hard coat layer 3 made of a material containing a (meth)acrylate resin on the surface of the laminate 10 opposite to the surface on which the adhesive layer 2 for bonding is disposed. In the configuration shown, the hard coat layer 3 is disposed on the surface opposite to the surface facing the second adhesive layer 15 (adhesive layer for bonding) of the third substrate 16.

[0094] The hard coat layer 3 has better scratch resistance than the PET films that make up the first substrate 12, the second substrate 14, and the third substrate 16, and has the function of improving the scratch resistance of the window film 1 as a whole.

[0095] This allows the window film 1 to exhibit better abrasion resistance after being attached to an adherend, and also more effectively prevents scratches during the process of attaching the window film 1 to an adherend.

[0096] [1-1-3-1] (Meth)acrylate resin The hard coat layer 3 is made of a material containing a (meth)acrylate resin, and the (meth)acrylate resin may, for example, contain urethane (meth)acrylate as a constituent component.

[0097] [1-1-3-1-1] Urethane (meth)acrylate The (meth)acrylate resin contains urethane (meth)acrylate as a constituent component, which provides sufficient flexibility, thereby making it possible to suppress the occurrence of cracks in the hard coat layer 3.

[0098] The urethane (meth)acrylate is a compound having at least a (meth)acryloyl group and a urethane bond, and has the property of being polymerized and cured by irradiation with energy rays. The urethane (meth)acrylate is, for example, an oligomer.

[0099] The number of (meth)acryloyl groups in the urethane (meth)acrylate (hereinafter also referred to as "number of functional groups") may be monofunctional, bifunctional, or trifunctional or more, but is preferably trifunctional or more.

[0100] The urethane (meth)acrylate can be obtained, for example, by reacting a polyol compound with a polyvalent isocyanate compound to obtain a terminal isocyanate urethane prepolymer, and then reacting the resulting prepolymer with a hydroxyl group-containing (meth)acrylate. The urethane (meth)acrylate can be used alone or in combination of two or more.

[0101] The polyol compound used as a raw material for the urethane (meth)acrylate is not particularly limited as long as it is a compound having two or more hydroxy groups, and examples thereof include alkylene diols, polyether polyols, polyester polyols, polycarbonate polyols, etc. Among these, polyester polyols are preferred.

[0102] The polyol compound may be any of a difunctional diol, a trifunctional triol, and a polyol having tetrafunctional or more, but a difunctional diol is preferred, and a polyester type diol is more preferred.

[0103] Examples of polyisocyanate compounds include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and ω,ω'-diisocyanatodimethylcyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, and naphthalene-1,5-diisocyanate. One or more compounds selected from these may be used in combination. Of these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferred.

[0104] The urethane (meth)acrylate can be obtained by reacting a (meth)acrylate having a hydroxy group with the isocyanate-terminated urethane prepolymer obtained by reacting the above-mentioned polyol compound with a polyisocyanate compound. The (meth)acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth)acryloyl group in at least one molecule.

[0105] Specific examples of (meth)acrylates having a hydroxy group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate; hydroxyl group-containing (meth)acrylamides such as N-methylol (meth)acrylamide; and reaction products obtained by reacting diglycidyl esters of vinyl alcohol, vinylphenol, and bisphenol A with (meth)acrylic acid. One or more of these can be used in combination. Among these, hydroxyalkyl (meth)acrylates are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred.

[0106] This makes it possible to provide the hard coat layer 3 with sufficiently excellent abrasion resistance while also providing the hard coat layer 3 with more suitable flexibility, and more effectively preventing the occurrence of cracks in the hard coat layer 3.

[0107] [1-1-3-1-2] Other monomer components The (meth)acrylate resin constituting the hard coat layer 3 may further contain a monomer component other than those mentioned above.

[0108] However, the content of components other than urethane (meth)acrylate in the (meth)acrylate resin constituting the hard coat layer 3 is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0109] [1-1-3-2] Other ingredients The hard coat layer 3 may contain components other than the above-mentioned (meth)acrylate resin. Hereinafter, in this section, such components will be referred to as "other components."

[0110] Examples of other components include photopolymerization initiators, antioxidants, ultraviolet absorbers, silane coupling agents, leveling agents, antistatic agents, antifoaming agents, and resin components other than (meth)acrylate resins.

[0111] However, the content of other components in the hard coat layer 3 is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0112] [1-1-3-3] Other conditions The thickness of the hard coat layer 3 is not particularly limited, but is preferably 0.1 μm to 20 μm, more preferably 0.2 μm to 15 μm, and even more preferably 0.4 μm to 10 μm.

[0113] This more effectively prevents the hard coat layer 3 from becoming excessively hard, while providing better abrasion resistance, and also improves the ease of handling of the window film 1 and the workability of, for example, attaching the window film 1 to an adherend. Furthermore, the occurrence of cracks and the like can be more suitably prevented.

[0114] [1-1-4] Easy adhesive layer In the laminate 10, an easy-adhesion layer (not shown) may be disposed on the surface on which the hard coat layer 3 is disposed, that is, on the surface of the third base material 16 in the illustrated configuration.

[0115] This makes it possible to improve the adhesion between the third substrate 16 and the hard coat layer 3.

[0116] Examples of materials constituting the easy-adhesion layer include resin polymers having the same components as the resin of the substrate. For example, when the first substrate 12 is a polyester resin (e.g., polyethylene terephthalate resin), examples of the resin polymer include low-molecular-weight polyesters (e.g., ethylene terephthalate oligomers) and water-soluble polyesters (e.g., water-soluble polyethylene terephthalate).

[0117] The thickness of the easy-adhesion layer is not particularly limited, but is preferably 10 nm or more and 1000 nm or less, more preferably 20 nm or more and 800 nm or less, and even more preferably 50 nm or more and 500 nm or less. This makes it possible to make the above-mentioned effects more pronounced.

[0118] If there is a large difference in refractive index between the hard coat layer 3 and the easy-adhesion layer, interference fringes may occur in the hard coat layer 3. If interference fringes occur in the hard coat layer 3, the appearance of the window film 1 as a whole may be impaired. In particular, when the window film 1 is attached to the indoor side of a window glass and viewed from the indoor side, visible light is reflected by the aluminum vapor-deposited film 11, and the occurrence of interference fringes is likely to be noticeable.

[0119] Therefore, the difference in refractive index between the hard coat layer 3 and the easy-adhesion layer is preferably 0.03 or less in absolute value, more preferably 0.02 or less, and even more preferably 0.015 or less.

[0120] This effectively prevents interference fringes from occurring in the hard coat layer 3, and prevents deterioration in the appearance of the window film 1 as a whole.

[0121] In addition, when an easy-adhesion layer is not formed on the surface of the third substrate 16, by making the refractive index of the hard coat layer 3 closer to the refractive index of the third substrate 16, it is possible to effectively suppress interference fringes caused by the difference in refractive index between the hard coat layer 3 and the third substrate 16, and to suppress deterioration in the appearance of the window film 1 as a whole.

[0122] [1-1-5] Other conditions The overall thickness of the window film 1 is preferably 150 μm or more and 500 μm or less, and more preferably 200 μm or more and 300 μm or less.

[0123] This makes the window film 1 easier to handle while still ensuring sufficient crime prevention performance.

[0124] Here, "total thickness" refers to the overall thickness of the window film 1 when it is attached to an adherend. Therefore, for example, even if a release liner 30 (described below) is disposed on the adhesive layer 2 during storage of the window film 1, the thickness of the release liner 30 is not included in the total thickness.

[0125] The visible light reflectance of the window film 1 as a whole is preferably 20% to 80%, more preferably 35% to 70%, and even more preferably 40% to 60%.

[0126] This allows the film to function as a mirror more effectively, reflecting the intruder more clearly, and further improving the crime prevention performance of the window film 1 as a whole.

[0127] In this specification, the visible light reflectance is a value measured by a method in accordance with JIS R3106:2019.

[0128] The visible light transmittance of the window film 1 as a whole is preferably 1% to 50%, more preferably 5% to 45%, and even more preferably 10% to 40%.

[0129] This allows the film to function as a mirror more effectively, reflecting the intruder more clearly, and further improving the crime prevention performance of the window film 1 as a whole.

[0130] In this specification, the visible light transmittance is a value measured by a method in accordance with JIS A5759:2016.

[0131] The elongation of the window film 1 as a whole is preferably 60% or more and 300% or less, more preferably 80% or more and 250% or less, and even more preferably 90% or more and 200% or less.

[0132] This makes it less likely to break even when an external force is applied, and the security performance of the window film 1 as a whole can be further improved.

[0133] In this specification, the elongation is a value measured by the method described in the examples below.

[0134] The tensile strength of the window film 1 as a whole is preferably 700 N / 25 mm or more, more preferably 750 N / 25 mm or more, and even more preferably 800 N / 25 mm or more.

[0135] This makes it less likely to break even when an external force is applied, and the security performance of the window film 1 as a whole can be further improved.

[0136] In this specification, the tensile strength is a value measured by the method described in the examples below.

[0137] [1-2] Second embodiment FIG. 2 is a cross-sectional view showing a second embodiment of the window film of the present invention.

[0138] This window film 1 includes a fourth substrate 18 and a fifth substrate 20 made of a material containing polyethylene terephthalate, in addition to a first substrate 12, a second substrate 14, and a third substrate 16 that constitute a laminate 10. In other words, the laminate 10 includes five substrates (PET films).

[0139] The second substrate 14, the third substrate 16, the fourth substrate 18 and the fifth substrate 20 are thinner than the second substrate 14 and the third substrate 16 that constitute the laminate 10 of the window film 1 shown in Figure 1.

[0140] In the illustrated configuration, the fourth substrate 18 is bonded to the second substrate 14 by a bonding adhesive layer (third adhesive layer 17). The fifth substrate 20 is bonded to the third substrate 16 by a bonding adhesive layer (fourth adhesive layer 19).

[0141] In this window film 1, an adhesive pressure-sensitive adhesive layer 2 is disposed on a fourth substrate 18 of a laminate 10, and a hard coat layer 3 is disposed on a fifth substrate 20.

[0142] [2] Release liner A release liner 30 may be disposed on the adhesive layer 2 of the window film 1 (see FIG. 1).

[0143] The release liner 30 is peeled off from the adhesive layer 2 when the window film 1 is to be stuck to an adherend.

[0144] The release liner 30 is not particularly limited and may be one that is commonly used in the field of window films 1. Examples of the release liner 30 include those in which a release layer is provided on the surface of a resin film substrate or a paper substrate.

[0145] Examples of materials constituting the resin film substrate include polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyacrylate, etc. Examples of materials constituting the paper substrate include polyethylene-laminated paper, polypropylene-laminated paper, clay-coated paper, resin-coated paper, glassine paper, and fine paper.

[0146] The release layer may contain a release agent such as silicone, long-chain alkyl resin, or fluorine-based resin.

[0147] The thickness of the release liner 30 is not particularly limited, but is preferably 10 μm or more and 50 μm or less. Furthermore, if the release layer is provided, the thickness of the release layer is preferably 0.01 μm or more and 5 μm or less.

[0148] As described above, the window film 1 includes multiple substrates and has a relatively large overall thickness. Therefore, if the window film 1 is wound into a roll with a relatively small diameter during storage, transportation, display, etc., a portion of the release liner 30 may peel off from the adhesive layer 2 of the window film 1, a phenomenon known as tunneling.

[0149] To cope with this, it is preferable to wrap the window film 1 so that the release liner 30, which is thinner than the laminate 10, is on the outside. This makes it possible to more effectively prevent tunneling when the window film 1 is wrapped with a small diameter.

[0150] [3] Window film manufacturing method Next, a method for manufacturing a window film will be described.

[0151] The window film 1 can be produced, for example, by applying a liquid composition (coating liquid) for forming the hard coat layer 3 to one surface of the laminate 10 to form the hard coat layer 3, and applying a liquid composition (coating liquid) for forming the adhesive pressure-sensitive adhesive layer 2 to the other surface of the laminate 10 to form the adhesive pressure-sensitive adhesive layer 2. In such a method, the order in which the hard coat layer 3 is formed and the adhesive pressure-sensitive adhesive layer 2 are formed is not particularly limited.

[0152] The laminate 10 can be produced, for example, as follows. That is, first, an aluminum vapor deposition film 11 is formed on one surface of a first base material 12 .

[0153] The aluminum vapor deposition film 11 may be formed by a known method, for example, a dry process such as PVD (physical vapor deposition) such as vacuum deposition, sputtering, or ion plating, or CVD (chemical vapor deposition) such as thermal CVD or atomic layer deposition (ALD).

[0154] Next, a composition for forming a pressure-sensitive adhesive layer is applied onto the second substrate 14 and dried to form the first pressure-sensitive adhesive layer 13.

[0155] The adhesive layer-forming composition can be prepared by dissolving or suspending the above-mentioned materials constituting the adhesive layer in an appropriate solvent. Examples of the solvent include esters such as ethyl acetate and butyl acetate; ketones such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; and aromatic hydrocarbons such as toluene and xylene. One or more of these can be used in combination.

[0156] The adhesive layer-forming composition may be applied by a known method, for example, a method using various coaters such as an air knife coater, a blade coater, a bar coater, a gravure coater, a roll coater, a roll knife coater, a curtain coater, a die coater, a knife coater, a screen coater, a Mayer bar coater, or a kiss coater.

[0157] Next, the first base material 12 is laminated on the first adhesive layer 13 so that the aluminum vapor deposition film 11 is in contact with the first adhesive layer 13 .

[0158] Subsequently, the second pressure-sensitive adhesive layer 15 is formed on the third substrate 16 in the same manner as above. Next, the first substrate 12 is laminated on the second pressure-sensitive adhesive layer 15. This allows for obtaining a laminate 10 in which the third substrate 16, the second pressure-sensitive adhesive layer 15, the first substrate 12, the aluminum vapor-deposited film 11, the first pressure-sensitive adhesive layer 13, and the second substrate 14 are laminated in this order.

[0159] The hard coat layer 3 can be formed by applying a liquid composition (coating liquid) for forming the hard coat layer 3 onto the third substrate 16 using, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like, and curing the applied composition by irradiating it with ultraviolet rays or an electron beam, or by heating.

[0160] The coating liquid for forming the hard coat layer 3 may contain components other than the above-mentioned components as needed, such as a thermosetting catalyst, a photopolymerization initiator, a solvent, etc.

[0161] Prior to the formation of the hard coat layer 3, an easy-adhesion layer may be formed by applying a composition for forming an easy-adhesion layer onto the third substrate 16.

[0162] Next, a composition for forming a pressure-sensitive adhesive layer is applied onto the second substrate 14 and dried to form the adhesive layer 2 for application.

[0163] A method for forming the adhesive layer 2 for adhesion may include, for example, forming the adhesive layer 2 for adhesion on a release liner 30 and laminating it so that the adhesive layer 2 for adhesion is in contact with the second substrate of the laminate 10.

[0164] [4] Adherent Next, an adherend to which the window film 1 is attached will be described.

[0165] Examples of the object to which the window film 1 is to be adhered include various window panes in buildings such as houses and buildings.

[0166] This means that even if the window glass is broken, the broken glass can be held in a sheet shape to prevent it from scattering, making it difficult to unlock or break into the window or door from the outside.

[0167] [5] How to apply window film Next, a method for applying the window film 1 will be described.

[0168] When the window film 1 is applied to a window glass substrate, if a release liner 30 is present, the release liner 30 is first peeled off to expose the adhesive layer 2, and the adhesive layer 2 is then adhered to the substrate, thereby enabling application. Application may also be performed using a method known as water application, in which application is performed at the interface between the adhesive layer 2 and the substrate via a working liquid prepared by adding a surfactant to water, and then the working liquid is scraped out using a tool known as a squeegee.

[0169] In particular, the window film 1 of this embodiment is preferably attached to the indoor side of the window glass, and is preferably attached so that at least the key portion of the window glass, such as the crescent lock or auxiliary lock, is hidden when viewed from the outdoor side.

[0170] This prevents someone from inserting their hand through a hole in the window glass to unlock the door, thereby providing a more effective crime prevention measure.

[0171] Furthermore, for example, a plurality of relatively small window films 1 may be attached in a line in the vertical or horizontal direction depending on the size and shape of the window glass.

[0172] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0173] For example, the window film may have a configuration other than those described above. More specifically, for example, at least one intermediate layer may be provided between the substrate and the aluminum vapor deposition film, between the substrate and the pressure-sensitive adhesive layer, or between the substrate and the hard coat layer 3, or at least one coating layer may be provided on the outer surface side of the hard coat layer.

[0174] In addition, in the above-described embodiment, an example was given in which the aluminum vapor deposition film and the second substrate, and the first substrate and the third substrate in the laminate were bonded via a bonding adhesive layer. However, for example, the aluminum vapor deposition film and the second substrate, and the first substrate and the third substrate may be bonded by fusion bonding or the like instead of using a bonding adhesive layer.

[0175] The window film may also have other functional layers, such as a heat-shielding layer, an anti-reflection layer, an ultraviolet-shielding layer, a printed layer, and the like.

[0176] Furthermore, the window film of the present invention may be produced by any method, and is not limited to the method described above.

[0177] For example, the window film of the present invention may be formed by applying a transfer method in which a composition for forming an adhesive layer for application is formed on one side of a release liner, and then the release liner provided with the adhesive layer for application is bonded to a laminate.

[0178] In addition, in the above-described embodiment, the hard coat layer and adhesive layer for application are formed after the laminate is formed. However, for example, the hard coat layer or adhesive layer for application may be formed on a substrate that will become part of the laminate, and then the laminate may be formed using the substrate. [Example]

[0179] The present invention will be described in detail below based on specific examples, but the present invention is not limited thereto. Treatments and measurements in the following examples, for which no temperature conditions are specified, were carried out at room temperature (23°C).

[0180] [6] Window film manufacturing Example 1 A window film having the configuration shown in FIG. 1 (Configuration 1) was produced as follows.

[0181] First, an aluminum vapor-deposited film was formed on one side of a 38 μm-thick PET film (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) as the first substrate, with a thickness such that the visible light transmittance was 15% and the visible light reflectance was 50%. Furthermore, 100 μm-thick PET films (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) were prepared as the second and third substrates.

[0182] Next, an acrylic adhesive (a mixture of 100 parts by mass of a copolymer (weight average molecular weight 600,000) of butyl acrylate / 2-hydroxyethyl acrylate / acrylic acid = 99 parts by mass / 0.8 parts by mass / 0.2 parts by mass) and 1 part by mass of an isocyanate-based crosslinking agent) was applied to one surface of the second substrate so that the thickness after drying would be 12 μm, and the coating was dried at 100°C for 1 minute to form a first adhesive layer with a thickness of 12 μm.

[0183] Next, the first base material was laminated onto the first pressure-sensitive adhesive layer so that the aluminum vapor-deposited film formed on the first base material was in contact with the first pressure-sensitive adhesive layer.

[0184] Next, the above acrylic adhesive was applied to one surface of the third substrate in the same manner as above and dried to form a second adhesive layer having a thickness of 12 μm.

[0185] Next, the first substrate was laminated onto the second adhesive layer so that the side of the first substrate opposite to the side on which the aluminum vapor deposition film was formed was in contact, thereby producing a laminate comprising three substrates.

[0186] Next, an aqueous polyester was applied onto the third substrate of the laminate to form an easy-adhesion layer. Thereafter, a liquid composition (coating liquid) for forming a hard coat layer was applied by a bar coating method while adjusting the amount of coating so that the film thickness after curing would be 2.5 μm, and an accumulated light dose of 200 mJ / cm 2 The coated film was irradiated with ultraviolet light of 1000 kJ / cm. Thereby, a hard coat layer was formed.

[0187] The liquid composition (coating liquid) for forming the hard coat layer was a solution prepared by dissolving a mixture of urethane (meth)acrylate, silica fine particles having acryloyl groups on the surface, and a photopolymerization initiator in propylene glycol as a solvent.

[0188] A 22 μm thick adhesive layer for adhesion was formed on the silicone surface of a 25 μm thick release liner, and the adhesive layer was laminated so that it was in contact with the second substrate of the laminate, resulting in a window film with an overall thickness of 286.5 μm.

[0189] In the obtained window film, the proportion of the monomer having an acidic group in the polymer serving as the adhesive in the first adhesive layer in contact with the aluminum vapor-deposited film was 0.2 mass %.

[0190] The refractive index of the easy-adhesion layer was 1.48, and the refractive index of the hard coat layer was 1.493. The absolute value of the difference between the refractive index of the hard coat layer and the refractive index of the easy-adhesion layer was 0.013.

[0191] Example 2 A window film was produced in the same manner as in Example 1, except that in the preparation of the coating liquid for forming the hard coat layer, the refractive index of the hard coat layer was changed to 1.528.

[0192] In the obtained window film, the absolute value of the difference between the refractive index of the hard coat layer and the refractive index of the easy-adhesion layer was 0.048.

[0193] Example 3 A window film was manufactured in the same manner as in Example 1, except that the first substrate was changed to a 50 μm thick PET film (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) and the visible light transmittance was set to 45% and the visible light reflectance to 25%.

[0194] Example 4 A window film having the configuration shown in FIG. 2 (Configuration 2) was produced as follows.

[0195] First, the second and third substrates were prepared as 50 μm thick PET films (manufactured by Toray Industries, Inc., Lumirror (registered trademark) T-60) and the fourth and fifth substrates were prepared as 50 μm thick PET films (manufactured by Toray Industries, Inc., Lumirror (registered trademark) T-60).

[0196] A laminate having three substrates was produced in the same manner as in Example 1, except that 50 μm-thick PET films were used as the second substrate and the third substrate. Then, the above-mentioned acrylic adhesive was applied to the surface of the second substrate in the same manner as above and dried to form a third adhesive layer having a thickness of 15 μm, and a fourth substrate was laminated onto the third adhesive layer.

[0197] In addition, the above-mentioned acrylic adhesive was applied to the surface of the third substrate in the same manner as above and dried to form a fourth adhesive layer with a thickness of 15 μm, and a fifth substrate was laminated onto the fourth adhesive layer to produce a laminate comprising five substrates.

[0198] An easy-adhesion layer and a hard coat layer were formed on the fifth substrate of the laminate in the same manner as in Example 1 above.

[0199] Furthermore, a pressure-sensitive adhesive layer for adhesion was formed on the fourth substrate of the laminate in the same manner as above to produce a window film.

[0200] (Comparative Example 1) A window film having the configuration shown in FIG. 3 (Configuration 3) was produced as follows.

[0201] First, a hard coat layer 3 was formed on one surface of a 50 μm thick second substrate 14 (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) in the same manner as in Example 1. Furthermore, an adhesive layer 2 for bonding was formed on the other surface of the second substrate 14 in the same manner as in Example 1, to produce a window film.

[0202] (Comparative Example 2) A window film having the configuration shown in FIG. 4 (Configuration 4) was produced as follows.

[0203] First, an aluminum vapor deposition film 11 having a thickness such that the visible light transmittance is 15% and the visible light reflectance is 50% was provided on one surface of a 38 μm thick PET film (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) serving as a first substrate 12.

[0204] Next, a second adhesive layer having a thickness of 15 μm was formed on one side of a third substrate 16 (manufactured by Toray Industries, Inc., Lumirror (registered trademark) T-60) having a thickness of 25 μm, and the first substrate 12 was laminated so that the side opposite to the side on which the aluminum vapor deposition film was formed was in contact with the second adhesive layer. Next, a hard coat layer 3 was formed on the third substrate 16 in the same manner as in Example 1 above.

[0205] Then, an adhesive layer 2 for adhesion was formed on the surface of the aluminum vapor-deposited film 11 provided on the first substrate 12 in the same manner as in Example 1, to produce a window film.

[0206] (Comparative Example 3) A window film having the configuration shown in FIG. 5 (Configuration 5) was produced as follows.

[0207] First, a second pressure-sensitive adhesive layer 15 was formed in the same manner as in Example 1 on one surface of a second substrate 14 (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) having a thickness of 100 μm.

[0208] Next, a third substrate 16 (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) having a thickness of 100 μm was laminated onto the second pressure-sensitive adhesive layer 15. Next, a hard coat layer 3 was formed on the third substrate 16 in the same manner as in Example 1 above.

[0209] Then, an adhesive layer 2 for adhesion was formed on the other surface of the second substrate 14 in the same manner as in Example 1, to produce a window film.

[0210] Comparative Example 4 A window film having the configuration shown in FIG. 6 (Configuration 6) was produced as follows.

[0211] First, a first pressure-sensitive adhesive layer 13 was formed in the same manner as in Example 1 on one surface of a first substrate 12 (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.) having a thickness of 100 μm. Next, a second substrate 14 having a thickness of 100 μm was laminated onto the first pressure-sensitive adhesive layer 13.

[0212] Next, a second pressure-sensitive adhesive layer 15 was formed on the other surface of the first substrate 12 in the same manner as in Example 1 above.

[0213] Next, a second adhesive layer was formed on one surface of a 100 μm-thick third substrate 16 (Lumirror (registered trademark) T-60, manufactured by Toray Industries, Inc.), and the first substrate was laminated so that the second adhesive layer was in contact with the first substrate. Next, a hard coat layer 3 was formed on the third substrate 16 in the same manner as in Example 1 above.

[0214] Then, an adhesive layer 2 for attachment was formed on the second substrate 14 in the same manner as in Example 1, to produce a window film.

[0215] [7] Window film evaluation The obtained window films were evaluated as follows.

[0216] [7-1]Visible light transmittance The visible light transmittance of the entire window film was measured using a method in accordance with JIS A5759: 2016. During the measurement, the glass surface of the test piece was placed facing the light source.

[0217] [7-2]Visible light reflectance The visible light reflectance of the entire window film was measured from the side opposite to the side on which the pressure-sensitive adhesive layer was laminated, using a method in accordance with JIS R3106:2019.

[0218] [7-3] Elongation and tensile strength Elongation and tensile strength were measured according to JIS A5759:2016. In an environment of 23°C and 50% RH, the window films produced in each of the examples and comparative examples were cut to a size of 25 mm wide x 150 mm long to obtain a measurement sample. The sample was placed in a tensile tester (Shimadzu Autograph AG-IS, manufactured by Shimadzu Corporation) so that the grip spacing was 100 mm. The sample was then pulled at a pulling speed of 300 mm / min, and the grip spacing at the time of sample breakage and the maximum load until breakage were defined as elongation (%) and tensile strength (N / 25 mm), respectively. The elongation is calculated by the following formula.

[0219] Elongation (%) = {(L-L0) / L0} x 100 L: Grip distance during cutting [mm] L0: Grip distance before tension [mm]

[0220] [7-4] Refractive Index The refractive indexes of the hard coat layer and the easy-adhesion layer were measured using a spectroscopic ellipsometer (M-2000, manufactured by JAWOOLLAM) at a measurement wavelength of 589 nm and a measurement temperature of 25°C according to a method in accordance with JIS K7142:2014.

[0221] [7-5] Evaluation of interference fringes The window films manufactured in the above examples and comparative examples were attached to a transparent glass plate.

[0222] The obtained adhesive sheet was visually inspected from the hard coat layer side under a three-band fluorescent lamp to check for interference fringes and was evaluated.

[0223] Table 1 shows the layer structure of the window film and the above evaluation results for each of the examples and comparative examples.

[0224] [Table 1]

[0225] As is clear from Table 1, the window film of the present invention exhibited good results in terms of visible light transmittance, visible light reflectance, elongation, and tensile strength. In other words, it was confirmed that the window film of the present invention is not only resistant to breakage even when subjected to external force, but also functions as a good mirror, allowing an intruder to be favorably reflected.

[0226] Furthermore, in Example 1, in which the difference in refractive index between the hard coat layer and the easy-adhesion layer was set to 0.013, the occurrence of interference fringes could be more suitably suppressed.

[0227] The window film of Example 1 was also wound around a cylindrical core with a diameter of 50 mm. When the film was wound with the release liner on the inside, tunneling, in which the release liner rose from the adhesive layer, was observed, but when the film was wound with the release liner on the outside, no tunneling was observed. In contrast, the comparative examples did not provide satisfactory results. [Explanation of symbols]

[0228] 1. Window film 2…Adhesive layer for pasting 3...Hard coat layer 10...Laminate 11...Aluminum vapor deposition film 12...First substrate 13...First adhesive layer 14...Second substrate 15...Second adhesive layer 16...Third substrate 17...Third adhesive layer 18...Fourth substrate 19...Fourth adhesive layer 20...5th substrate 30...Release liner

Claims

1. a laminate including an aluminum vapor-deposited film, a first substrate made of a material containing polyethylene terephthalate and disposed on a first surface side of the aluminum vapor-deposited film, and a second substrate made of a material containing polyethylene terephthalate and disposed on a second surface side of the aluminum vapor-deposited film, the second surface side being the surface opposite to the first surface; A window film characterized by having an adhesive layer for adhering to an adherend, arranged on the side of the second substrate opposite the side facing the aluminum vapor deposition film.

2. The window film according to claim 1 , wherein the aluminum vapor deposition film is provided on the surface of the first substrate.

3. The window film according to claim 1 or 2, wherein the laminate has a bonding adhesive layer that bonds the aluminum vapor deposition film and the second substrate together.

4. 4. The window film according to claim 3, wherein the polymer serving as the adhesive constituting the adhesive layer for bonding has a content of a monomer containing an acidic group of 0.5% by mass or less.

5. The window film according to claim 1 or 2, wherein the laminate comprises three to five substrates made of a material containing polyethylene terephthalate.

6. 3. The window film according to claim 1, further comprising a hard coat layer made of a material containing a (meth)acrylate resin on the surface of the laminate opposite to the surface on which the adhesive layer is disposed.

Images