window film

Abstract

To provide a window film capable of combining, at a high level, excellent adhesion with an adherend and suppression of occurrence of glue slippage when adhering to the adherend.SOLUTION: A window film of the present invention is a window film comprising a base material and an adhesive layer provided on one side of the base material, the adhesive layer comprising a material composed of an acrylic adhesive and a silane coupling agent, the silane coupling agent is 3-trimethoxysilylpropyl succinic anhydride, and the 3-trimethoxysilylpropyl succinic anhydride is contained in the adhesive layer as a reaction product with the acrylic adhesive. It is preferable that proportion of 3-trimethoxysilylpropyl succinic anhydride is 0.01 pt.mass or more and 10 pts.mass to 100 pts.mass of the acrylic adhesive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Window films are adhesive films applied to the window glass of vehicles such as automobiles, ships, and trains, and buildings such as houses, apartment buildings, and office buildings, and are widely used for purposes such as blocking ultraviolet and / or infrared rays in sunlight, protecting privacy, preventing crime, preventing glass from shattering, and decoration (see, for example, Patent Document 1).

[0003] A widely used method for applying window films is a water-based application method, which allows for easy reapplication and position adjustment. This involves spraying an application liquid made by adding a surfactant to water onto the surface of the adherend, then laminating the window film on the adherend, and applying pressure with a tool called a squeegee to push out any air or moisture between the window film and the adherend, thereby adhering the window film (see, for example, Patent Document 2).

[0004] When adhering a window film to an adherend as described above, after laminating the window film to the adherend, the position may be adjusted by manually pushing and shifting the window film before applying pressure. However, this can cause misalignment between the base material and the pressure-sensitive adhesive layer of the window film, known as adhesive misalignment. Adhesive misalignment of the window film can result in a deterioration in appearance and functionality.

[0005] Such adhesive slippage is a problem caused by the high adhesive strength between the window film and the substrate, and it has been difficult to achieve a high level of both good adhesion to the substrate and the prevention of adhesive slippage when the film is applied to the substrate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-012082 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-150392 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 can achieve both good adhesion to an adherend and suppression of adhesive misalignment at a high level when applied to the adherend. [Means for solving the problem]

[0008] Such an object can be achieved by the present invention described below. The window film of the present invention is a window film comprising a substrate and a pressure-sensitive adhesive layer provided on one surface side of the substrate, the pressure-sensitive adhesive layer is made of a material containing an acrylic pressure-sensitive adhesive and a silane coupling agent, the acrylic pressure-sensitive adhesive contains, as monomer components, a (meth)acrylic acid alkyl ester in a proportion of 50% by mass or more and 99% by mass or less, and a (meth)acrylic acid hydroxyalkyl ester in a proportion of 0.5% by mass or more and 20% by mass or less; The silane coupling agent is 3-trimethoxysilylpropylsuccinic anhydride, and the 3-trimethoxysilylpropylsuccinic anhydride is contained in the pressure-sensitive adhesive layer as a reaction product with the acrylic pressure-sensitive adhesive.

[0009] In the present invention, the content of the 3-trimethoxysilylpropylsuccinic anhydride in the pressure-sensitive adhesive layer is preferably 0.01 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the acrylic pressure-sensitive adhesive.

[0011] In the present invention, the (meth)acrylic acid hydroxyalkyl ester is selected from the group consisting of hydroxymethyl (meth)acrylate, 2-(meth)acrylic acid Hydroxyethyl It is preferable that the acrylate is one or more selected from the group consisting of 3-hydroxypropyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate.

[0012] In the present invention, the pressure-sensitive adhesive layer preferably further contains an ultraviolet absorber. In the present invention, the substrate is preferably made of a material containing polyester.

[0013] In the present invention, the thickness of the pressure-sensitive adhesive layer is preferably 1 μm or more and 100 μm or less.

[0014] In the present invention, it is preferable that a release liner be provided on the surface of the pressure-sensitive adhesive layer opposite to the substrate. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a window film that can achieve a high level of both good adhesion to an adherend and suppression of adhesive slippage when applied to an adherend. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing one example of the configuration of a window film of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present invention will be described in detail below. [1] Window film First, the window film of the present invention will be described.

[0018] FIG. 1 is a cross-sectional view showing an example of the structure of the window film of the present invention. The window film 1 includes a substrate 2 and an adhesive layer 3 provided on one surface of the substrate 2. The adhesive layer 3 is made of a material containing an acrylic adhesive and a silane coupling agent, and the silane coupling agent is 3-trimethoxysilylpropylsuccinic anhydride, which is contained in the adhesive layer 3 as a reaction product with the acrylic adhesive.

[0019] As represented by the following formula (1), 3-trimethoxysilylpropylsuccinic anhydride is a silane coupling agent having an alkoxysilyl group and an acid anhydride group.

[0020] [ka]

[0021] As shown in the following formula (2), 3-trimethoxysilylpropylsuccinic anhydride reacts with the acrylic adhesive in the adhesive layer 3, and the acid anhydride moiety is present in a ring-opened state. In other words, 3-trimethoxysilylpropylsuccinic anhydride is contained in the adhesive layer 3 as a reaction product with the acrylic adhesive. In this way, the silane coupling agent having an acid anhydride group has excellent reactivity with the acrylic adhesive and provides superior adhesive strength. In particular, the adhesive layer 3 and the substrate 2 have excellent adhesion.

[0022] [ka]

[0023] Furthermore, when the substrate of the window film 1 is glass, the adhesive layer 3 contains a silane coupling agent having an alkoxysilyl group, so that when the window film 1 is attached to the glass by so-called water lamination, the alkoxysilyl group of the silane coupling agent is hydrolyzed to generate SiOH, which is adsorbed to the glass surface by hydrogen bonding, or forms a covalent bond of -O-Si-O- with the glass, thereby providing excellent adhesion between the adhesive layer 3 and the glass.

[0024] Thus, in the window film 1 of the present invention, the adhesive layer 3 contains 3-trimethoxysilylpropylsuccinic anhydride, which is a silane coupling agent having an alkoxysilyl group and an acid anhydride group, and therefore the adhesive layer 3 has excellent adhesion to both the adherend and the substrate 2.

[0025] This prevents misalignment between the substrate 2 and the adhesive layer 3, or so-called adhesive misalignment, even if the window film 1 is manually pushed and shifted to adjust its position when it is attached to glass.

[0026] As mentioned above, adhesive slippage occurs due to the high adhesive strength between the window film 1 and the substrate, but the present invention can effectively suppress the occurrence of adhesive slippage while maintaining the high adhesive strength between the window film 1 and the substrate.

[0027] As a result, the present invention can provide a window film 1 that can achieve a high level of both good adhesion to the substrate and suppression of adhesive slippage when applied to the substrate.

[0028] The excellent effects of the present invention are obtained by the window film 1 having the above-mentioned configuration, but cannot be obtained if the window film 1 does not have the above-mentioned configuration. For example, if the pressure-sensitive adhesive layer 3 does not contain 3-trimethoxysilylpropylsuccinic anhydride as a silane coupling agent, the pressure-sensitive adhesive layer 3 will not have excellent adhesion to both the adherend and the substrate 2, and the intended effects of the present invention will not be obtained.

[0029] [1-1] Base material The substrate 2 has the function of supporting the pressure-sensitive adhesive layer 3 .

[0030] The substrate 2 may be made of any material. For example, the constituent material of the substrate 2 may be various resin materials, but it is preferable that the substrate 2 be made of a material containing polyester, and it is more preferable that the substrate 2 be made mainly of polyester.

[0031] This improves the handleability of the window film 1 and improves the workability of attaching the window film 1 to an adherend, etc. Furthermore, the durability of the window film 1 is improved.

[0032] In this specification, the term "mainly" refers to the part of interest that has the highest content.

[0033] In particular, the content of polyester in the base material 2 is preferably 90% by mass or more, and more preferably 95% by mass or more.

[0034] Examples of polyesters that can be used to form the substrate 2 include polyethylene terephthalate and polybutylene terephthalate, with polyethylene terephthalate being preferred.

[0035] This improves the handleability of the window film 1 and the workability of attaching the window film 1 to an adherend, etc. Also, the durability of the window film 1 is improved. Also, the adhesion to the pressure-sensitive adhesive layer 3 made of a material described below is improved.

[0036] The substrate 2 may contain components other than those mentioned above. Examples of such components include colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, antistatic agents, polymerization inhibitors, crosslinking agents, catalysts, leveling agents, thickeners, and dispersants.

[0037] The substrate 2 may have a substantially uniform composition throughout, or may have regions with different compositions. For example, the substrate 2 may be a laminate including multiple layers with regions with different compositions (including, for example, resin materials with different molecular weights), or may be made of a gradient material whose composition changes gradually along the thickness direction.

[0038] The substrate 2 may be subjected to a surface treatment to enhance adhesion to the pressure-sensitive adhesive layer 3. Examples of such surface treatments include corona treatment and application of an adhesion improver such as a urethane-based, polyester-based, polyethylene-based, polyethyleneimine-based, or acrylic-based one.

[0039] These surface treatment methods are appropriately selected depending on the material constituting the substrate 2, but generally, application of an adhesion improver is preferred in terms of effectiveness and operability.

[0040] The thickness of the substrate 2 is not particularly limited, but is preferably 10 μm or more and 500 μm or less, more preferably 15 μm or more and 400 μm or less, and even more preferably 20 μm or more and 300 μm or less.

[0041] This not only improves the durability of the window film 1, but also improves the handleability of the window film 1, facilitating tasks such as application to an adherend. In addition, the ability to conform to the shape of a curved adherend is improved, effectively preventing wrinkles and the like.

[0042] [1-2] Adhesive layer The pressure-sensitive adhesive layer 3 has the function of coming into contact with and bonding to an adherend when the window film 1 is stuck to the adherend.

[0043] The adhesive layer 3 is made of a material containing an acrylic adhesive and 3-trimethoxysilylpropylsuccinic anhydride as a silane coupling agent.

[0044] [1-2-1] Acrylic adhesive The acrylic adhesive may contain a (meth)acrylic monomer as a monomer component of the structural unit, but it is preferable that the monomer components include a (meth)acrylic acid alkyl ester and a (meth)acrylic acid hydroxyalkyl ester.

[0045] In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid.

[0046] The number of carbon atoms in the alkyl group of the (meth)acrylic acid alkyl ester is preferably 1 or more and 20 or less, and more preferably 1 or more and 12 or less. The alkyl group in the (meth)acrylic acid alkyl ester may be a straight chain or a branched chain.

[0047] Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (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.

[0048] Among these, from the viewpoint of adhesiveness, the (meth)acrylic acid alkyl ester is preferably 2-ethylhexyl (meth)acrylate, methyl (meth)acrylate, or butyl (meth)acrylate, more preferably butyl (meth)acrylate, and even more preferably butyl acrylate.

[0049] Examples of hydroxyalkyl (meth)acrylates include hydroxymethyl (meth)acrylate, 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, and one or more selected from these may be used in combination.

[0050] Among these, the (meth)acrylic acid hydroxyalkyl ester is preferably one or more selected from the group consisting of hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0051] This makes it possible to ensure a higher cohesive force, and the above-mentioned effects can be made more pronounced.

[0052] When the acrylic pressure-sensitive adhesive contains a (meth)acrylic acid alkyl ester and a (meth)acrylic acid hydroxyalkyl ester as monomer components, the content of the (meth)acrylic acid alkyl ester in the acrylic pressure-sensitive adhesive is preferably 50% by mass or more and 99% by mass or less, and more preferably 60% by mass or more and 95% by mass or less.

[0053] Furthermore, when the acrylic pressure-sensitive adhesive contains a (meth)acrylic acid alkyl ester and a (meth)acrylic acid hydroxyalkyl ester as monomer components, the content of the (meth)acrylic acid hydroxyalkyl ester in the acrylic pressure-sensitive adhesive is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1.0% by mass or more and 18% by mass or less, and even more preferably 1.5% by mass or more and 15% by mass or less.

[0054] When the content of the (meth)acrylic acid alkyl ester and the (meth)acrylic acid hydroxyalkyl ester satisfies the above conditions, the above-mentioned effects can be made even more remarkable.

[0055] The acrylic pressure-sensitive adhesive may contain (meth)acrylic acid as a monomer component. In particular, the acrylic pressure-sensitive adhesive preferably contains (meth)acrylic acid as a monomer component in addition to the (meth)acrylic acid alkyl ester and the (meth)acrylic acid hydroxyalkyl ester.

[0056] When the acrylic pressure-sensitive adhesive contains (meth)acrylic acid as a monomer component, the content of (meth)acrylic acid in the acrylic pressure-sensitive adhesive is preferably 0.1% by mass or more and 30.0% by mass or less, more preferably 0.2% by mass or more and 20.0% by mass or less, and even more preferably 0.3% by mass or more and 10.0% by mass or less.

[0057] The acrylic pressure-sensitive adhesive may further contain other monomer components as structural units. Examples of the other monomer components 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, and nitrile-based monomers such as acrylonitrile and methacrylonitrile. One or more selected from these may be used in combination.

[0058] When the acrylic pressure-sensitive adhesive further contains the other monomer component as a constituent unit, the content of the other monomer component in the acrylic pressure-sensitive adhesive is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 10% by mass or less.

[0059] In the adhesive layer 3, the content of the acrylic adhesive is preferably 75% by mass or more and 99.99% by mass or less, more preferably 85% by mass or more and 99.95% by mass or less, and even more preferably 90% by mass or more and 99.9% by mass or less. This makes it possible to make the above-mentioned effects even more pronounced.

[0060] [1-2-2] Silane coupling agents The pressure-sensitive adhesive layer 3 contains 3-trimethoxysilylpropylsuccinic anhydride as a silane coupling agent.

[0061] As described above, 3-trimethoxysilylpropylsuccinic anhydride reacts with the acrylic adhesive in the adhesive layer 3, and the acid anhydride moiety is present in a ring-opened state.

[0062] An example of a commercially available product of such 3-trimethoxysilylpropylsuccinic anhydride is "X-12-967C" manufactured by Shin-Etsu Chemical Co., Ltd.

[0063] The content of 3-trimethoxysilylpropylsuccinic anhydride in the adhesive layer 3 is preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.05 parts by mass or more and 8 parts by mass or less, and even more preferably 0.1 parts by mass or more and 6 parts by mass or less, relative to 100 parts by mass of the acrylic adhesive.

[0064] This can improve the adhesion between the pressure-sensitive adhesive layer 3 and the substrate 2. Furthermore, by ensuring that the content of 3-trimethoxysilylpropylsuccinic anhydride is within the above range, the adhesive strength between the window film 1 and the adherend is prevented from becoming excessively high, and adhesive slippage during application can be more effectively prevented.

[0065] [1-2-3] UV absorbers The pressure-sensitive adhesive layer 3 may further contain an ultraviolet absorber.

[0066] 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.

[0067] The content of the ultraviolet absorber in the adhesive layer 3 is preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the solid content in the adhesive composition.

[0068] [1-2-4] Other ingredients The pressure-sensitive adhesive layer 3 may contain components other than those described above as long as it is made of a material containing an acrylic pressure-sensitive adhesive and a silane coupling agent. Hereinafter, in this section, such components will be referred to as "other components."

[0069] Examples of other components include adhesives other than acrylic adhesives, coupling agents other than 3-trimethoxysilylpropylsuccinic anhydride, solvents, crosslinking agents, dispersants, tackifiers, ultraviolet absorbers, antioxidants, polymerization initiators, light stabilizers, heat stabilizers, softeners, fillers, colorants, and antistatic agents, and one or more selected from these may be used in combination.

[0070] However, the content of other components in the pressure-sensitive adhesive layer is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0071] The content of 3-trimethoxysilylpropylsuccinic anhydride in the adhesive layer 3 is preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.05 parts by mass or more and 8 parts by mass or less, and even more preferably 0.1 parts by mass or more and 6 parts by mass or less, relative to 100 parts by mass of the acrylic adhesive.

[0072] [1-2-5] Other conditions The thickness of the pressure-sensitive adhesive layer 3 is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 80 μm or less, and even more preferably 10 μm or more and 60 μm or less.

[0073] This not only improves the durability of the window film 1, but also improves the handleability of the window film 1, making it easier to perform tasks such as attaching the film to an adherend. In addition, the film is able to conform to the shape of a curved adherend, effectively preventing wrinkles and the like.

[0074] [1-3] Release liner In the window film 1 , a release liner 4 may be disposed on the surface of the pressure-sensitive adhesive layer 3 opposite to the substrate 2 .

[0075] This effectively prevents dust and the like from adhering to the adhesive layer 3 and the adhesive layer 3 from adhering to undesired areas during storage, transportation, etc. of the manufactured window film 1.

[0076] The release liner 4 is peeled off from the pressure-sensitive adhesive layer 3 when the window film 1 is to be stuck to an adherend.

[0077] The release liner 4 may be, for example, a sheet made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyarylate, etc., or a base material made of various paper materials such as polyethylene-laminated paper, polypropylene-laminated paper, clay-coated paper, resin-coated paper, glassine paper, or high-quality paper, with the surface of this base material in contact with the adhesive layer 3 being subjected to a release treatment as necessary.

[0078] Examples of the release treatment include forming a release agent layer made of a release agent such as a silicone resin, a long-chain alkyl resin, or a fluorine-based resin.

[0079] The thickness of the release liner 4 is not particularly limited, but is preferably, for example, 10 μm to 400 μm. Furthermore, when the release layer is provided, the thickness of the release layer is preferably, for example, 0.01 μm to 5 μm.

[0080] [1-4] Other conditions The thickness of the window film 1 is not particularly limited, but is preferably 11 μm to 600 μm, more preferably 18 μm to 500 μm, and even more preferably 20 μm to 400 μm.

[0081] This not only improves the durability and UV absorption function of the window film 1, but also improves the handleability of the window film 1, making it easier to apply the film to an adherend. In addition, the film is more easily conformable to the shape of a curved adherend, more effectively preventing wrinkles and the like.

[0082] The thickness of the window film 1 does not include the thickness of the release liner 4. In other words, it is the thickness of only the portion that is attached to the adherend.

[0083] The window film 1 is preferably transparent so as not to impair the appearance of the adherend.

[0084] In this specification, "transparent" means that the transmittance in the visible light region is 60% or more (upper limit 100%), and preferably 80% or more (upper limit 100%). The transmittance of the window film 1 can be measured by a method in accordance with JIS A5759:2016 (Films for architectural glazing - Visible light transmittance test).

[0085] The window film 1 preferably has a yellowness index (YI) of 4 or less, more preferably 3.5 or less, and even more preferably 2.5 or less.

[0086] This makes it possible to obtain a window film 1 in which coloring is more suitably suppressed, and which has better transparency and colorlessness, making it more suitable as a window film 1.

[0087] The yellowness index (YI) of the window film 1 can be measured by a method in accordance with JIS K7373:2006.

[0088] In accordance with the adhesive strength measurement method of JIS A5759:2016, the window film 1 is cut to a width of 25 mm and pressed onto a float glass plate using a 2 kg roller with one back and forth motion.After leaving the film for 24 hours in an environment of 23°C and relative humidity of 50%, the adhesive strength measured at an angle of 180° and a peeling speed of 300 mm / min is preferably 9 N / 25 mm or more, more preferably 10 N / 25 mm or more, and even more preferably 11 N / 25 mm or more.

[0089] This allows the window film 1 to have better adhesion to the adherend.

[0090] [2] Window film manufacturing method Next, a method for manufacturing a window film will be described.

[0091] First, the substrate 2 as described above is prepared, and the pressure-sensitive adhesive layer 3 is formed on the substrate 2 . The method for forming the pressure-sensitive adhesive layer 3 is not particularly limited, but examples thereof include a method in which a composition for forming the pressure-sensitive adhesive layer 3 containing the components described above is applied onto the substrate 2.

[0092] The coating method is not particularly limited, and the coating can be performed using a known coating device such as a roll coater, knife coater, air knife coater, bar coater, blade coater, slot die coater, lip coater, or gravure coater.

[0093] After applying the composition for forming the pressure-sensitive adhesive layer 3 onto the substrate 2, a drying treatment is carried out to form the pressure-sensitive adhesive layer 3. The drying conditions at this time are not particularly limited, and for example, the drying is carried out under conditions of 60°C or higher and 150°C or lower for 10 seconds or higher and 120 seconds or lower. A release liner 4 for protecting the pressure-sensitive adhesive layer 3 may be attached onto the pressure-sensitive adhesive layer 3 .

[0094] However, the manufacturing method of the window film 1 is not limited to this, and the window film 1 may be manufactured, for example, by applying a composition for forming the adhesive layer 3 to a release liner 4, and then contacting the composition applied to the release liner 4 with the substrate 2.

[0095] The pressure-sensitive adhesive layer 3 can be formed on the release liner 4 in the same manner as described above.

[0096] [3] Adherent Next, an adherend to which the window film 1 is attached will be described.

[0097] The window film 1 is suitably applied to window glass of buildings such as houses and buildings, and vehicles such as automobiles and trains, as well as mirrors, glass cases, and show windows.

[0098] In particular, it is preferable that the adherend has a chemical structure of —Si—OH on the surface to which the window film 1 is applied.

[0099] [4] How to apply window film Next, a method for applying the window film 1 will be described.

[0100] When the window film 1 is to be attached to an adherend such as a window glass, if a release liner 4 is present, the release liner 4 is first peeled off to expose the adhesive layer 3, and the adhesive layer 3 is then adhered to the adherend, thereby allowing the film to be attached.

[0101] Here, it is preferable to apply the window film 1 by a method known as water lamination, in which an application liquid prepared by adding a surfactant to water is sprayed onto the surface of the adherend, and then the window film 1 is laminated onto the adherend, and pressure is applied with a tool called a squeegee to push out air, moisture, etc. between the window film 1 and the adherend, thereby adhering the window film 1.

[0102] This allows for suitable adjustment of the position of the window film 1. Furthermore, workability is improved, and air bubbles remaining between the adherend and the window film 1 can be suitably prevented.

[0103] In particular, with conventional window films 1, the above-mentioned problem of adhesive misalignment occurred significantly when adjusting the position of the window film 1 during water application. In contrast, with the window film 1 of the present invention, the occurrence of the above-mentioned problem can be sufficiently suppressed.

[0104] The window film 1 of this embodiment can be suitably applied to both the inside of a windowpane of a building or automobile, so-called interior application, and the outside of a windowpane, so-called exterior application.

[0105] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0106] For example, the window film may have a configuration other than those described above. More specifically, for example, the window film may have at least one intermediate layer between the substrate and the pressure-sensitive adhesive layer, or may further have at least one coating layer (such as a hard coating layer) on the outer surface side of the substrate. [Example]

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0108] 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).

[0109] [5] Window film manufacturing Example 1 An acrylic adhesive was prepared by mixing and copolymerizing 80% by mass of butyl acrylate, 8% by mass of methyl acrylate, 5% by mass of vinyl acetate, 1% by mass of acrylic acid, and 6% by mass of 2-hydroxyethyl methacrylate as monomers.

[0110] 100 parts by mass (solids) of the prepared acrylic adhesive was blended with 5 parts by mass of 3-trimethoxysilylpropylsuccinic anhydride (X-12-967C, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent and 4 parts by mass of a triazine-based ultraviolet absorber (TINUVIN477, manufactured by BASF), and the mixture was thoroughly stirred to obtain a coating liquid for forming an adhesive layer.

[0111] A release liner was prepared by providing a silicone-based release layer on one side of a 25 μm thick polyethylene terephthalate film.

[0112] The adhesive layer-forming coating liquid was applied to the release layer side of the release liner using a roll knife coater so that the thickness after drying would be 20 μm, and the coating was dried by heating at 90° C. for 1 minute to form an adhesive layer.

[0113] As the substrate, a 188 μm thick, highly adhesive polyester film "Cosmoshine A4360" (manufactured by Toyobo Co., Ltd.) was prepared.

[0114] The pressure-sensitive adhesive layer formed on the release liner was attached to a substrate to produce a window film.

[0115] Examples 2 to 7 A window film was produced in the same manner as in Example 1, except that in preparing the coating liquid for forming the adhesive layer, the monomer composition of the acrylic adhesive and the amount of 3-trimethoxysilylpropylsuccinic anhydride added were changed as shown in Table 1.

[0116] (Comparative Examples 1 to 6) A window film was produced in the same manner as in Example 1, except that in preparing the coating liquid for forming the adhesive layer, the monomer composition of the acrylic adhesive and the type and amount of the silane coupling agent were changed as shown in Table 1.

[0117] [6] Window film evaluation The obtained window films were evaluated as follows.

[0118] [6-1] Evaluation of adhesive strength First, a window film was cut into a sample 25 mm wide and 150 mm long in accordance with the adhesive strength measurement method of JIS A5759: 2016. Next, the release film was removed and the adhesive layer of the window film was pressed against a float glass plate using a 2 kg rubber roller, which was moved back and forth once under conditions of 23°C and 50% RH.

[0119] Next, using a tensile testing machine (manufactured by Orientec Co., Ltd., product name "Tensilon"), the sample was peeled at an angle of 180° and at a peeling speed of 300 mm / min in accordance with the adhesive strength measurement method of JIS A5759:2016, and the adhesive strength at that time was measured.

[0120] An adhesive strength of 10 N / 25 mm or more was rated as "○" (pass), and an adhesive strength of less than 10 N / 25 mm was rated as "×" (fail).

[0121] [6-2] Evaluation of glue slippage The window film was cut into a sample having a width of 25 mm and a length of 50 mm.

[0122] A solution of water containing a surfactant was sprayed onto the adhesive layer of the sample and onto the 3mm thick float glass of the adherend, and the window film was fixed to the glass. After rubbing the window film with a squeegee to remove the water, the sample was pushed with a finger to shift it 1cm on the glass surface.

[0123] When light was transmitted through the window film, the presence or absence of whitening was visually confirmed. The whitening was then rated on a 5-point scale from 1 to 5, with "5" representing the weakest whitening and "1" representing the strongest whitening.

[0124] A rating of 5 or 4 was considered "○" (pass), and a rating of 3 to 1 was considered "×" (fail).

[0125] Table 1 summarizes the results of the above evaluations for each of the Examples and Comparative Examples, along with the structure of the pressure-sensitive adhesive layer. In Table 1, butyl acrylate is represented as "BA," vinyl acetate as "Vac," methyl acrylate as "MA," acrylic acid as "AA," 2-hydroxyethyl methacrylate as "HEMA," 4-hydroxybutyl acrylate as "4HBA," 2-ethylhexyl acrylate as "2EHA," and isobutyl acrylate as "i-BA." The silane coupling agents listed in Table 1 are all product names manufactured by Shin-Etsu Chemical Co., Ltd., with X-12-967C being 3-trimethoxysilylpropylsuccinic anhydride represented by the above formula (1), KBM403 being represented by the following formula (3), KBE402 being represented by the following formula (4), KBM4803 being represented by the following formula (5), and KBM3066 being represented by the following formula (6). In Table 1, the amount of silane coupling agent added is shown as a ratio to 100 parts by mass of the acrylic adhesive, and the content of each monomer in the acrylic adhesive composition is expressed in mass %.

[0126] [ka]

[0127] [ka]

[0128] [ka]

[0129] [ka]

[0130] [Table 1]

[0131] As is clear from Table 1, in each of the above examples containing 3-trimethoxysilylpropyl succinic anhydride as a silane coupling agent together with the acrylic adhesive, high adhesive strength was obtained in the 180° peel test, and whitening was weak in the adhesive slippage test, resulting in good results.

[0132] As described above, the window films of the examples were able to achieve both good adhesion to the adherend and high levels of adhesive slippage.

[0133] In contrast, in the comparative examples in which a silane compound other than 3-trimethoxysilylpropylsuccinic anhydride was used as a silane coupling agent, the adhesive slippage test showed severe whitening and unsatisfactory results were not obtained.Furthermore, in the comparative examples, sufficient adhesive strength was not obtained in the 180° peel test. [Explanation of symbols]

[0134] 1:Window film 2: Base material 3: Adhesive layer 4: Release liner

Claims

1. A window film comprising a substrate and a pressure-sensitive adhesive layer provided on one surface of the substrate, the pressure-sensitive adhesive layer is made of a material containing an acrylic pressure-sensitive adhesive and a silane coupling agent, the acrylic pressure-sensitive adhesive contains, as monomer components, a (meth)acrylic acid alkyl ester in a proportion of 50% by mass or more and 99% by mass or less, and a (meth)acrylic acid hydroxyalkyl ester in a proportion of 0.5% by mass or more and 20% by mass or less; The window film is characterized in that the silane coupling agent is 3-trimethoxysilylpropylsuccinic anhydride, and the 3-trimethoxysilylpropylsuccinic anhydride is contained in the pressure-sensitive adhesive layer as a reaction product with the acrylic pressure-sensitive adhesive.

2. The window film according to claim 1, wherein the content of the 3-trimethoxysilylpropyl succinic anhydride in the pressure-sensitive adhesive layer is 0.01 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the acrylic pressure-sensitive adhesive.

3. The window film according to claim 1 or 2, wherein the (meth)acrylic acid hydroxyalkyl ester is one or more selected from the group consisting of hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

4. 4. The window film according to claim 1, wherein the pressure-sensitive adhesive layer further contains an ultraviolet absorber.

5. The window film according to any one of claims 1 to 4, wherein the substrate is made of a material containing polyester.

6. 6. The window film according to claim 1, wherein the thickness of the pressure-sensitive adhesive layer is 1 μm or more and 100 μm or less.

7. 7. The window film according to claim 1, wherein a release liner is provided on the surface of the pressure-sensitive adhesive layer opposite to the substrate.

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