Window film

Abstract

To provide a window film that exhibits an excellent black appearance when attached to an adherend, has a hard coat layer with excellent abrasion resistance, and resistance to heat damage during production.SOLUTION: A window film of the present invention comprises: a substrate; a hard coat layer provided on one surface of the substrate; and an adhesive agent layer provided on another surface of the substrate. The hard coat layer is made of a material containing a cured product of an ultraviolet curable resin, carbon black, and titanium nitride. The cured product of the ultraviolet curable resin is formed by a polymerization reaction using a composition containing a photopolymerization initiator having a maximum absorption peak in a wavelength range of 300 nm or less in an ultraviolet region of 210 nm or more. A ratio of carbon black to 100.0 pts.mass of titanium nitride is 25.0 pts.mass or more to 85.0 pts.mass or less.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, condominiums, and office buildings, and are widely used for blocking ultraviolet and / or infrared rays in sunlight, protecting privacy, preventing crime, preventing glass from shattering, decoration, etc. A hard coat layer may also be provided to improve the scratch resistance (scratch resistance) of the window film surface.

[0003] Depending on the purpose, window films may need to adjust sunlight, and window films with a so-called sunlight adjustment function are in demand. In order to impart a sunlight adjustment function to window films, for example, a colored substrate made of a material containing a synthetic resin colored black or the like is used (Patent Document 1).

[0004] However, because the color of the window film is determined by the masterbatch that is mixed into the resin material during the production of the substrate, it is difficult to adjust to a variety of black colors with different colors and visible light transmittances. Furthermore, the colored substrate also poses the problem of susceptibility to heat damage, such as the generation of wrinkles, during the production of the window film, specifically, during the UV curing of the hard coat layer on the substrate and the drying of the adhesive layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 02-043045 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a window film that exhibits an excellent black appearance when attached to an adherend, has a hard coat layer that has excellent abrasion resistance, and is resistant to heat damage during production. [Means for solving the problem]

[0007] Such an object can be achieved by the present invention described below. The window film of the present invention comprises a substrate, a hard coat layer provided on one surface of the substrate, and a pressure-sensitive adhesive layer provided on the other surface of the substrate, the hard coat layer is made of a material containing a cured product of an ultraviolet curable resin, carbon black, and titanium nitride; the cured product of the ultraviolet curable resin is formed by a polymerization reaction using a composition containing a photopolymerization initiator having a maximum absorption peak in a wavelength region of 300 nm or less in the ultraviolet region of 210 nm or more, The ratio of the carbon black to 100.0 parts by mass of the titanium nitride is 25.0 parts by mass or more and 85.0 parts by mass or less.

[0008] In the present invention, the proportion of the carbon black is preferably 0.005 parts by mass or more and 6.0 parts by mass or less with respect to 100.0 parts by mass of the cured product of the ultraviolet curable resin.

[0009] In the present invention, the ratio of the titanium nitride to 100.0 parts by mass of the cured product of the ultraviolet curable resin is preferably 0.02 parts by mass or more and 7.0 parts by mass or less.

[0010] In the present invention, the proportion of the amount of the photopolymerization initiator used relative to 100.0 parts by mass of the polymerizable component constituting the ultraviolet curable resin is preferably 0.3 parts by mass or more and 18.0 parts by mass or less.

[0011] In the present invention, the thickness of the hard coat layer is preferably 0.2 μm or more and 20.0 μm or less. In the present invention, the substrate is preferably made of a material containing polyester. [Effects of the Invention]

[0012] According to the present invention, a window film can be provided which exhibits an excellent black appearance when attached to an adherend, has a hard coat layer with excellent abrasion resistance, and is resistant to heat damage during production. [Brief explanation of the drawings]

[0013] [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

[0014] Preferred embodiments of the present invention will be described in detail below. [1] Window film FIG. 1 is a cross-sectional view showing an example of the structure of the window film of the present invention.

[0015] The window film 1 includes a substrate 2, a hard coat layer 3 provided on one side of the substrate 2, and a pressure-sensitive adhesive layer 4 provided on the other side of the substrate 2. The hard coat layer 3 is composed of a material containing a cured product of an ultraviolet-curable resin, carbon black, and titanium nitride, and the cured product of the ultraviolet-curable resin is formed by a polymerization reaction using a composition containing a photopolymerization initiator that has a maximum absorption peak in the ultraviolet wavelength range of 210 nm or more and 300 nm or less. In the hard coat layer 3, the ratio of carbon black to 100.0 parts by mass of titanium nitride is 25.0 parts by mass or more and 85.0 parts by mass or less.

[0016] With this configuration, it is possible to provide a window film 1 that exhibits an excellent black appearance when attached to an adherend, has a hard coat layer 3 with excellent abrasion resistance, and is resistant to heat damage during production.

[0017] Such effects are achieved because the hard coat layer 3 contains both carbon black and titanium nitride, and the compounding ratio of the carbon black to titanium nitride is limited to the above range, thereby achieving a suitable blackish hue. Furthermore, by coloring the hard coat layer 3, which is thinner than the substrate 2, the window film 1 is less susceptible to heat damage during production, specifically, during the formation of the hard coat layer 3 and the adhesive layer 4, for example. Furthermore, the photopolymerization initiator used in the curing reaction of the ultraviolet-curable resin has a maximum absorption peak in the ultraviolet region of 210 nm or more and in the wavelength region of 300 nm or less. This reduces the transmittance of the ultraviolet region in the short wavelength region due to the carbon black, and effectively prevents the curing reaction of the ultraviolet-curable resin constituting the hard coat layer 3 from progressing sufficiently, thereby effectively preventing a decrease in the hardness and abrasion resistance of the hard coat layer 3.

[0018] In the present invention, the wavelength region defining the absorption peak of the photopolymerization initiator is specified to be 210 nm or more in the ultraviolet region because this wavelength region allows efficient curing of ultraviolet-curable resins using commercially available light sources. Light components below 210 nm are either rarely contained in ordinary commercially available light sources or are light components that are not suitable for curing ultraviolet-curable resins.

[0019] The excellent effects of the present invention can be obtained by the window film 1 having the above-mentioned configuration, and cannot be obtained if the window film 1 does not have the above-mentioned configuration.

[0020] For example, if carbon black and titanium nitride are contained in the substrate rather than in the hard coat layer, it becomes difficult to produce a window film in a wide variety of black-based colors with different colors and visible light transmittances.

[0021] Furthermore, the colored substrate makes the window film more susceptible to heat damage during manufacturing.

[0022] Furthermore, for example, if the ratio of carbon black to 100.0 parts by mass of titanium nitride in the hard coat layer is outside the above range, the following problems arise: If the ratio of carbon black to 100.0 parts by mass of titanium nitride is less than 25.0 parts by mass, the appearance of the window film when attached to the adherend will have a bluish tint; if the ratio of carbon black to 100.0 parts by mass of titanium nitride is more than 85.0 parts by mass, the appearance of the window film when attached to the adherend will have a brownish tint.

[0023] Furthermore, if the photopolymerization initiator used in the curing reaction of the UV-curable resin does not have a maximum absorption peak in the wavelength range of 300 nm or less in the UV range of 210 nm or more, the following problems arise. That is, if the photopolymerization initiator does not have a maximum absorption peak in the wavelength range of 300 nm or less in the UV range of 210 nm or more, but has a maximum absorption peak in the wavelength range less than 210 nm, the light irradiated for the curing reaction of the UV-curable resin cannot be sufficiently transmitted by the carbon black, and the curing reaction of the UV-curable resin cannot proceed smoothly. As a result, the hardness and abrasion resistance of the hard coat layer are inferior. Furthermore, if the photopolymerization initiator does not have a maximum absorption peak in the wavelength range of 300 nm or less in the UV range of 210 nm or more, but has a maximum absorption peak in the wavelength range over 300 nm, the composition for forming the hard coat layer will cure under the influence of light from light sources such as sunlight, fluorescent lamps, and LED lights before being applied and irradiated with UV light, making it impossible to obtain a coated product with a good surface condition.

[0024] In the present invention, the "maximum absorption peak" refers to the wavelength at which the absorbance is greatest among the wavelengths at which the absorbance is maximum in the absorption spectrum. The absorbance can be measured, for example, using a solution in which the target photopolymerization initiator is dissolved at a concentration of 0.1% by mass. In this case, for example, acetonitrile can be used as the solvent.

[0025] [1-1] Base material The substrate 2 has the function of supporting the hard coat layer 3 and the pressure-sensitive adhesive layer 4 .

[0026] 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.

[0027] 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.

[0028] In this specification, the term "mainly" refers to the part of interest that has the highest content.

[0029] 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.

[0030] Examples of polyesters that can be used to form the substrate 2 include polyethylene terephthalate and polybutylene terephthalate, with polyethylene terephthalate being preferred.

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

[0032] The substrate 2 may contain components other than those mentioned above. Examples of such components include colorants, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, heat stabilizers, lubricants, and antistatic agents.

[0033] 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.

[0034] The substrate 2 may be subjected to a surface treatment to enhance adhesion to the hard coat layer 3 and the pressure-sensitive adhesive layer 4.

[0035] 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.

[0036] 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.

[0037] The thickness of the substrate 2 is not particularly limited, but is preferably 10 μm or more and 300 μm or less, more preferably 15 μm or more and 200 μm or less, and even more preferably 18 μm or more and 100 μm or less.

[0038] This not only provides shatterproof properties for 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.

[0039] [1-2] Hard coat layer The hard coat layer 3 has better scratch resistance than the substrate 2, and has the function of improving the scratch resistance of the window film 1 as a whole.

[0040] This allows the window film 1 to exhibit excellent abrasion resistance after being attached to an adherend, and also effectively prevents scratches during the process of attaching the window film 1 to an adherend.

[0041] In the present invention, the hard coat layer 3 is made of a material containing a cured product of an ultraviolet curable resin, carbon black, and titanium nitride.

[0042] [1-2-1] UV-curable resin hardened product The cured product of the ultraviolet curable resin contained in the hard coat layer 3 is formed by irradiating ultraviolet rays and polymerizing the polymerizable compound through the action of a photopolymerization initiator, which will be described in detail later.

[0043] [1-2-1-1]Polymerizable compound The polymerizable compound is not particularly limited, but for example, a (meth)acrylate compound can be suitably used.

[0044] In this specification, the term "(meth)acrylate" is a concept that includes both acrylate and methacrylate.

[0045] In particular, tri- or higher functional polyfunctional (meth)acrylate compounds and urethane (meth)acrylate compounds are suitable materials.

[0046] This allows the hard coat layer 3 to have sufficiently excellent transparency, while also providing the hardness and scratch resistance of the hard coat layer 3 with improved properties.

[0047] Examples of (meth)acrylate compounds include trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerol tri(meth)acrylate, triallyl(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0048] When a tri- or higher functional polyfunctional (meth)acrylate compound is contained, the polyfunctional (meth)acrylate compound may be tri- or higher functional, but is preferably penta- or higher functional. This makes it possible to more significantly exhibit the above-mentioned effects.

[0049] 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. Urethane (meth)acrylate is, for example, an oligomer.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] A urethane (meth)acrylate can be obtained by reacting a (meth)acrylate having a hydroxy group with a terminal isocyanate 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.

[0055] 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.

[0056] When the cured product of the ultraviolet-curable resin constituting the hard coat layer 3 contains at least one of a tri- or higher functional polyfunctional (meth)acrylate compound and a urethane (meth)acrylate compound as a polymerizable compound, it may further contain other polymerizable compounds. Hereinafter, such components will also be referred to as "other components" in this section.

[0057] Examples of other components include difunctional or lower functional (meth)acrylate compounds.

[0058] However, in such a case, the proportion of other components in the total polymerizable compounds constituting the cured product of the ultraviolet-curable resin contained 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.

[0059] [1-2-1-2] Photopolymerization initiator As described above, the cured product of the ultraviolet curable resin constituting the hard coat layer 3 is formed by a polymerization reaction using a composition containing a photopolymerization initiator having a maximum absorption peak in the wavelength region of 300 nm or less in the ultraviolet region of 210 nm or more.

[0060] The wavelength region in which the photopolymerization initiator has its maximum absorption peak in the ultraviolet region of 210 nm or more is 300 nm or less, preferably 230 nm or more and 290 nm or less, and more preferably 240 nm or more and 280 nm or less. This makes the above-mentioned effects more pronounced.

[0061] The photopolymerization initiator may have a maximum absorption peak in a wavelength region of 300 nm or shorter in the ultraviolet region of 210 nm or longer, and may have multiple absorption peaks in the wavelength region of 300 nm or shorter, or may have an absorption peak other than the maximum absorption peak in a wavelength region longer than 300 nm in addition to the maximum absorption peak present in the wavelength region of 300 nm or shorter.

[0062] The photopolymerization initiator may also have an absorption peak in a wavelength region other than the ultraviolet region of 210 nm or more.

[0063] The absorbance at that wavelength of a 0.1% by mass solution of the photopolymerization initiator is preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and most preferably 0.5 or more. This makes the above-mentioned effects more pronounced.

[0064] Examples of the photopolymerization initiator include 1-[4-(2-hydroxyethoxyl)-phenyl]-2-hydroxy-methoxypropanone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexyl-phenyl ketone, a mixture of oxy-phenyl-acetic acid-2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid-2-[2-hydroxy-ethoxy]-ethyl ester, and a mixture of a compound represented by the following formula and propylene carbonate. One or more of these may be used in combination.

[0065] [ka]

[0066] This makes the above-mentioned effects more pronounced.

[0067] The proportion of the amount of the photopolymerization initiator used relative to 100.0 parts by mass of the polymerizable component constituting the ultraviolet-curable resin is preferably 0.3 parts by mass or more and 18.0 parts by mass or less, more preferably 0.5 parts by mass or more and 15.0 parts by mass or less, and even more preferably 1.5 parts by mass or more and 10.0 parts by mass or less.

[0068] This allows the polymerization reaction of the ultraviolet-curable resin to proceed more smoothly during the production of the window film 1, thereby improving the hardness and scratch resistance of the hard coat layer 3 and the durability of the window film 1.

[0069] [1-2-1-3] Other conditions The content of the cured product of the ultraviolet curable resin in the hard coat layer 3 is preferably 30.0% by mass or more and 99.0% by mass or less, more preferably 50.0% by mass or more and 95.0% by mass or less, and even more preferably 60.0% by mass or more and 93.0% by mass or less. This makes it possible to more significantly exhibit the above-mentioned effects.

[0070] [1-2-2] Carbon Black The hard coat layer 3 contains carbon black.

[0071] In the hard coat layer 3, the ratio of carbon black to 100.0 parts by mass of titanium nitride may be 25.0 parts by mass or more and 85.0 parts by mass or less, preferably 30.0 parts by mass or more and 80.0 parts by mass or less, and more preferably 40.0 parts by mass or more and 70.0 parts by mass or less.

[0072] This allows the above-mentioned effects to be exhibited more significantly, and also allows the color and light transmittance of the window film 1 to be suitably adjusted.

[0073] The content of carbon black in the hard coat layer 3 is preferably 0.005 parts by mass or more and 6.0 parts by mass or less, more preferably 0.0075 parts by mass or more and 4.0 parts by mass or less, and even more preferably 0.01 parts by mass or more and 2.0 parts by mass or less, relative to 100.0 parts by mass of the cured product of the ultraviolet-curable resin.

[0074] This allows the window film 1 to have a more excellent color when attached to an adherend.

[0075] [1-2-3] Titanium nitride The hard coat layer 3 contains titanium nitride.

[0076] The content of titanium nitride in the hard coat layer 3 is preferably 0.02 parts by mass or more and 7.0 parts by mass or less, more preferably 0.03 parts by mass or more and 5.5 parts by mass or less, and even more preferably 0.04 parts by mass or more and 4.0 parts by mass or less, relative to 100.0 parts by mass of the cured product of the ultraviolet-curable resin.

[0077] This allows the window film 1 to have a more excellent color when attached to an adherend.

[0078] [1-2-4] Other ingredients The hard coat layer 3 may contain components other than the above-mentioned components. Hereinafter, in this section, such components will also be referred to as "other components."

[0079] Examples of other components include carbon black, colorants other than titanium nitride, near-infrared absorbers other than cesium tungsten oxide, photopolymerization initiators other than those mentioned above, light stabilizers, antioxidants, ultraviolet absorbers, silane coupling agents, leveling agents, antistatic agents, and antifoaming agents.

[0080] However, the proportion 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.

[0081] [1-2-5] Other conditions The hard coat layer 3 can be formed by applying a liquid composition (coating liquid) for forming the hard coat layer 3 onto the substrate 2 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 coating by irradiating it with ultraviolet rays or an electron beam or by heating. Alternatively, heating may be performed while irradiating it with ultraviolet rays or an electron beam.

[0082] If necessary, components other than the above-mentioned components may be contained in the coating liquid for forming the hard coat layer 3. Examples of such components include a thermosetting catalyst and a solvent.

[0083] The thickness of the hard coat layer 3 is not particularly limited, but is preferably 0.2 μm to 20.0 μm, more preferably 0.4 μm to 16.0 μm, and even more preferably 0.6 μm to 12.0 μm.

[0084] This not only provides even better abrasion resistance and weather resistance, but also improves the ease of handling of the window film 1 and improves the workability of, for example, attaching the window film 1 to an adherend. In addition, the occurrence of wrinkles, curls, and the like can be suitably prevented.

[0085] [1-3] Adhesive layer The pressure-sensitive adhesive layer 4 generally has excellent flexibility and is the part that adheres closely to the adherend.

[0086] Examples of adhesives that can be used to form the adhesive layer 4 include natural rubber adhesives, synthetic rubber adhesives, acrylic adhesives, polyvinyl ether adhesives, urethane adhesives, and silicone adhesives.

[0087] Among these, acrylic adhesives, urethane adhesives, and silicone adhesives are particularly suitable from the standpoint of weather resistance and the like.

[0088] Specific examples of acrylic adhesives include copolymers of butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, methyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, and the like.

[0089] The adhesive layer 4 only needs to be composed mainly of an adhesive, and may contain components other than the adhesive.

[0090] Examples of such components include crosslinking agents, ultraviolet absorbers, silane coupling agents, tackifiers, fillers, softeners, antioxidants, light stabilizers, 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.

[0091] The adhesive layer 4 can be formed, for example, by applying a liquid composition (coating liquid) for forming the adhesive layer 4 onto the substrate 2 by various coating methods such as roll coating, gravure coating, reverse coating, knife coating, die coating, and bar coating.

[0092] The pressure-sensitive adhesive layer 4 can be formed by drying the coating film of the coating liquid. The coating liquid may have a different composition from the pressure-sensitive adhesive layer 4. For example, after the coating liquid is applied, the solvent contained therein may be removed, or the degree of polymerization or crosslinking may be made different by allowing a curing reaction or a crosslinking reaction to proceed.

[0093] Alternatively, the pressure-sensitive adhesive layer 4 may be formed on a release liner 10 first, and then attached to the substrate 2.

[0094] The thickness of the pressure-sensitive adhesive layer 4 is not particularly limited, but is preferably, for example, 1 μm to 100 μm, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 60 μm.

[0095] This not only improves the durability of the window film 1, but also makes it easier to handle and apply (stick) the window film 1 to an adherend. In addition, the ability to conform to the shape of a curved adherend is improved, effectively preventing wrinkles and the like.

[0096] [1-4] Other conditions The window film 1 may be, for example, an interior film that is attached to the interior surface of the window glass, or an exterior film that is attached to the exterior surface of the window glass, but is preferably an interior film.

[0097] The thickness of the window film 1 is not particularly limited, but is preferably 11 μm to 400 μm, more preferably 18 μm to 230 μm, and even more preferably 20 μm to 100 μm.

[0098] This not only improves the durability of the window film 1, but also improves the handling properties of the window film 1, making it easier to apply the film to an adherend, etc. Furthermore, it improves the ability to conform to the shape of a curved adherend, effectively preventing wrinkles and the like.

[0099] Here, "the thickness of the window film 1" 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 10 (described below) is disposed on the pressure-sensitive adhesive layer 4 during storage of the window film 1, the thickness of the release liner 10 is not included in the thickness.

[0100] [2] Release liner A release liner 10 may be disposed on the pressure-sensitive adhesive layer 4 of the window film 1 .

[0101] The release liner 10 is peeled off from the pressure-sensitive adhesive layer 4 when the window film 1 is to be stuck to an adherend.

[0102] The release liner 10 is not particularly limited and may be one that is commonly used in the field of window films. Examples of the release liner 10 include a release liner having a release layer on the surface of a resin film substrate or a paper substrate.

[0103] 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.

[0104] The release layer may contain a release agent such as silicone, long-chain alkyl resin, or fluorine-based resin.

[0105] The thickness of the release liner 10 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.

[0106] [3] Adherent Next, an adherend to which the window film 1 is attached will be described.

[0107] 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.

[0108] This allows for optimal adjustment of sunlight, effectively suppressing temperature increases inside the room or vehicle due to sunlight.

[0109] [4] How to apply window film Next, a method for applying the window film 1 will be described.

[0110] When the window film 1 is applied to an adherend such as a window glass, if a release liner 10 is present, the application can be performed by first peeling off the release liner 10 to expose the pressure-sensitive adhesive layer 4, and then adhering the pressure-sensitive adhesive layer 4 to the adherend. Here, application can also be performed by a method known as water application, in which application is performed at the interface between the pressure-sensitive adhesive layer 4 and the adherend via an application liquid prepared by adding a surfactant to water, and then scraping out the application liquid using a tool known as a squeegee.

[0111] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0112] 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 between the substrate and the hard coat layer, or may further have at least one coating layer on the outer surface side of the hard coat layer. [Example]

[0113] 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).

[0114] [5] Window film manufacturing Example 1 First, a liquid composition (coating liquid) for forming a hard coat layer was prepared using Aronix M-403 (manufactured by Toagosei Co., Ltd.) as a mixture of ultraviolet-curable pentafunctional acrylate compounds and hexafunctional acrylate compounds, carbon black, titanium nitride, Omnirad 754 (manufactured by IGM Resins BV) as a photopolymerization initiator, and methyl ethyl ketone as a solvent.

[0115] The photopolymerization initiator had a maximum absorption peak at a wavelength of 260 nm in the ultraviolet region of 210 nm or more.

[0116] Furthermore, a 50 μm thick film made of polyethylene terephthalate (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360") was prepared as a substrate. The substrate was uncolored and transparent.

[0117] The coating solution for forming the hard coat layer was applied to one side of this substrate by bar coating so that the film thickness after curing would be 5 μm, and after drying at 70 °C for 1 minute, it was exposed to an integrated light intensity of 150 mJ / cm 2 As a result, a hard coat layer containing a cured product of the ultraviolet curable resin, carbon black, and titanium nitride was formed.

[0118] In the formed hard coat layer, the proportion of carbon black was 0.3 parts by mass, the proportion of titanium nitride was 1 part by mass, and the proportion of titanium nitride was 30 parts by mass, relative to 100.0 parts by mass of the cured product of the ultraviolet curable resin.

[0119] Next, a composition containing an acrylic adhesive was applied by knife coating to the surface of the substrate opposite to the surface on which the hard coat layer was formed, and then dried at 90°C for 2 minutes to form an adhesive layer with a thickness of 10 μm.

[0120] Furthermore, a release liner was prepared, which had a release layer containing a silicone-based release agent formed on one side of a 38 μm-thick polyethylene terephthalate film.

[0121] Then, the release layer of the release liner was attached to the pressure-sensitive adhesive layer to obtain a window film in which the pressure-sensitive adhesive layer was protected by the release liner.

[0122] Examples 2 to 5 A window film was produced in the same manner as in Example 1, except that the composition of the coating liquid for forming the hard coat layer was adjusted to have the structure of the hard coat layer as shown in Table 1.

[0123] (Comparative Examples 1 to 5) A window film was produced in the same manner as in Example 1, except that the composition of the coating liquid for forming the hard coat layer was adjusted and the integrated amount of ultraviolet light applied to the substrate coated with the coating liquid was adjusted to form the hard coat layer as shown in Table 1.

[0124] (Comparative Example 6) The substrate was made of a material containing 100 parts by mass of polyethylene terephthalate, 0.3 parts by mass of carbon black, and 1 part by mass of titanium nitride. A window film was produced in the same manner as in Example 1, except that carbon black and titanium nitride were not used as components of the coating liquid for forming the hard coat layer.

[0125] [6] Window film evaluation The obtained window films were evaluated as follows.

[0126] [6-1] Hard coat layer abrasion test The surface of the hard coat layer of the obtained window film was wiped with steel wool #0000 at a rate of 250 g / cm 2 The scraping test was carried out by rubbing the sample 10 times with a pressure of 0.01 mm.

[0127] The Δ haze was calculated from the haze values ​​before and after the scratch test. ΔHaze (%) = Haze value after scratch test (%) - Haze value before scratch test (%)

[0128] The haze value was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: NDH-5000) according to a method in accordance with JIS K7136:2000.

[0129] The curability of the hard coat layer was evaluated according to the following criteria.

[0130] ◯: Δ haze is less than 1.5%. ×: Δ haze is 1.5% or more.

[0131] [6-2] Thermal damage evaluation The window film, which had been subjected to heat during the manufacturing process, was placed on a flat plate, and the distance from the flat plate surface at the point furthest from the surface was measured. The thermal damage to the window film was assessed according to the following criteria. The greater the distance, the greater the thermal damage.

[0132] ○: The distance is less than 20 mm. ×: The distance is 20 mm or more.

[0133] [6-3] Color The obtained window film was attached to a glass and visually observed to evaluate the color.

[0134] Table 1 shows the results of the above evaluations for each of the examples and comparative examples, along with the conditions of the hard coat layer and the substrate.

[0135] In Table 1, the cured product of the UV-curable resin is referred to as "cured product," carbon black as "CB," Omnirad 754 (manufactured by IGM Resins BV), a photopolymerization initiator with a maximum absorption peak at a wavelength of 260 nm in the ultraviolet region of 210 nm or more, is referred to as "PI1," Omnirad 184 (manufactured by IGM Resins BV), a photopolymerization initiator with a maximum absorption peak at a wavelength of 240 nm in the ultraviolet region of 210 nm or more, is referred to as "PI2," Omnirad 2959 (manufactured by IGM Resins BV), a photopolymerization initiator with a maximum absorption peak at a wavelength of 275 nm in the ultraviolet region of 210 nm or more, is referred to as "PI3," and Omnirad 369 (manufactured by IGM Resins BV), a photopolymerization initiator with a maximum absorption peak at a wavelength of 325 nm in the ultraviolet region of 210 nm or more, is referred to as "PI4." PET) was designated as "PI4," Cosmoshine A4360 manufactured by Toyobo Co., Ltd. was designated as "transparent PET," and the substrate used in Comparative Example 6 was designated as "black PET."

[0136] [Table 1]

[0137] As is clear from Table 1, excellent results were obtained in each of the above examples, whereas satisfactory results were not obtained in each of the above comparative examples. [Explanation of symbols]

[0138] 1:Window film 2: Base material 3: Hard coat layer 4: Adhesive layer 10: Release liner

Claims

1. a substrate, a hard coat layer provided on one surface of the substrate, and a pressure-sensitive adhesive layer provided on the other surface of the substrate; the hard coat layer is made of a material containing a cured product of an ultraviolet curable resin, carbon black, and titanium nitride; the cured product of the ultraviolet curable resin is formed by a polymerization reaction using a composition containing a photopolymerization initiator having a maximum absorption peak in a wavelength region of 300 nm or less in the ultraviolet region of 210 nm or more, A window film characterized in that the ratio of the carbon black to 100.0 parts by mass of the titanium nitride is 25.0 parts by mass or more and 85.0 parts by mass or less.

2. 2. The window film according to claim 1, wherein the ratio of the carbon black to 100.0 parts by mass of the cured product of the ultraviolet curable resin is 0.005 parts by mass or more and 6.0 parts by mass or less.

3. 3. The window film according to claim 1, wherein the ratio of the titanium nitride to the cured product of the ultraviolet curable resin is 0.02 parts by mass or more and 7.0 parts by mass or less.

4. 3. The window film according to claim 1, wherein the ratio of the amount of the photopolymerization initiator used to the polymerizable component constituting the ultraviolet curable resin: 100.0 parts by mass is 0.3 parts by mass or more and 18.0 parts by mass or less.

5. 3. The window film according to claim 1, wherein the hard coat layer has a thickness of 0.2 μm or more and 20.0 μm or less.

6. The window film according to claim 1 or 2, wherein the substrate is made of a material containing polyester.

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