External window film

Abstract

The external window film of the present invention comprises a substrate, a hard coating disposed on one side of the substrate, and an adhesive layer disposed on the side opposite to the hard coating side of the substrate. The hard coating is formed of a material containing a (meth)acrylate resin as a component of urethane (meth)acrylate, a hindered amine light stabilizer, and a UV absorber. In the external window film of the present invention, the proportion of the hindered amine light stabilizer relative to 100.0 parts by weight of the (meth)acrylate resin is 2.0 parts by weight or more and 15.0 parts by weight or less, and the proportion of the UV absorber is 5.0 parts by weight or more and 30.0 parts by weight or less.

Description

Technical Field

[0001] This invention relates to an external window film. Background Technology

[0002] Window film is an adhesive film applied to the window glass of vehicles such as cars, ships, and trains, as well as buildings such as residences, apartments, and office buildings. Window film is widely used for blocking ultraviolet and / or infrared rays from sunlight, protecting privacy, preventing crime, preventing glass breakage, and for decoration.

[0003] For example, a window film may include a transparent substrate, a rigid coating layer placed on one side of the substrate, and an adhesive layer on the other side of the rigid coating layer opposite to the substrate. Additionally, by incorporating a UV absorber into the adhesive layer, the window film effectively blocks ultraviolet light (e.g., Patent Document 1).

[0004] In interior window film applied to the interior side of window glass, sunlight passes through in the following order: window glass / adhesive layer / substrate / hard coating / interior. In this case, because the adhesive layer can block ultraviolet rays, it protects the hard coating from ultraviolet radiation, thus inhibiting the degradation of the hard coating caused by ultraviolet rays.

[0005] On the other hand, for customers who wish to apply window film to the outside of windows due to the structure of the building, an external window film that is applied to the outside of the window glass has also been developed.

[0006] In this type of exterior window film, sunlight travels through the hard coating layer, substrate, adhesive layer, window glass, and interior in that order. Therefore, the adhesive layer cannot block ultraviolet (UV) rays and thus cannot protect the hard coating layer from UV damage, leading to UV degradation of the hard coating layer.

[0007] In addition to sunlight, rain, wind, and temperature changes can also cause the hard coating of exterior window films to deteriorate.

[0008] Furthermore, since cranes and other equipment are used when installing window film from the outside, it is desirable to transport as much window film as possible to the installation location in a single operation.

[0009] Therefore, in order to ensure that the hard coating of the window film is on the outside, the window film is transported in a rolled-up state. At this time, no cracks must appear in the hard coating.

[0010] If cracks form in the hard coating, problems such as reduced transparency, as well as decreased appearance and performance may occur.

[0011] [Reference Technical Documents]

[0012] [Patent Literature]

[0013] [Patent Document 1] Re-Table 2018 / 1173979. Summary of the Invention

[0014] [The problem this invention aims to solve]

[0015] The purpose of this invention is to provide an external window film with a hard coating that can maintain transparency, prevent cracks in the hard coating when rolled up, and has excellent weather resistance.

[0016] [Problem-solving methods]

[0017] This objective is achieved by the present invention having the following structure. Furthermore, these structures can be combined arbitrarily in the present invention.

[0018] The external window film of the present invention includes a substrate, a hard coating disposed on one side of the substrate, and an adhesive layer disposed on the side of the substrate opposite to the side where the hard coating is disposed.

[0019] The hard coating is composed of a (meth)acrylate resin containing urethane (meth)acrylate as a component, a hindered amine light stabilizer, and a UV absorber.

[0020] The product is characterized in that, relative to 100.0 parts by weight of (meth)acrylate resin, the proportion of hindered amine light stabilizer is 2.0 parts by weight or more and 15.0 parts by weight or less, and the proportion of ultraviolet absorber is 5.0 parts by weight or more and 30.0 parts by weight or less.

[0021] In this invention, the ultraviolet absorber preferably contains a compound having a benzophenone structure and a compound having a hydroxyphenyltriazine structure.

[0022] In this invention, the ratio of the content of the compound having a benzophenone structure to the content of the compound having a hydroxyphenyltriazine structure in the hard coating is preferably 1.0:2.0 or more and 2.0:1.0 or less by mass.

[0023] In this invention, the (meth)acrylate resin preferably has a structure obtained by polymerizing urethane (meth)acrylate using a photopolymerization initiator.

[0024] In this invention, the photopolymerization initiator is preferably a triphenylphosphine oxide compound because its ultraviolet absorption wavelength is more biased towards the longer wavelength side than that of ultraviolet absorbers.

[0025] In this invention, the thickness of the hard coating is preferably 0.1 μm or more and 20 μm or less.

[0026] In this invention, the substrate is preferably made of a material containing polyester.

[0027] [Invention Effects]

[0028] According to the present invention, an external window film equipped with a hard coating can be provided that ensures transparency while preventing cracks in the hard coating during winding and has excellent weather resistance. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view illustrating an example of the structure of the outer window film of the present invention.

[0030] Figure 2 This is a micrograph of the surface of the outer window film of Example 1 after accelerated aging test.

[0031] Figure 3 This is a micrograph of the surface of the outer window film after accelerated aging test in Comparative Example 1.

[0032] Figure 4 This is a micrograph of the surface of the outer window film after accelerated aging test in Comparative Example 3.

[0033] Figure 5 This is a micrograph of the surface of the outer window film after accelerated aging test of ratio 6.

[0034] Figure 6 This is a surface micrograph of the outer window film of Comparative Example 1 before accelerated aging testing.

[0035] [Symbol Explanation]

[0036] 1: External window film

[0037] 2: Substrate

[0038] 3: Hard coating

[0039] 4: Adhesive layer

[0040] 10: Peel off the liner. Detailed Implementation

[0041] The preferred embodiments of the present invention will now be described in detail.

[0042] [1] Window film

[0043] Figure 1 This is a cross-sectional view illustrating an example of the structure of the outer window film of the present invention.

[0044] The external window film 1 includes a substrate 2, a hard coating layer 3 disposed on one side of the substrate 2, and an adhesive layer 4 on the opposite side to the side where the hard coating layer 3 is disposed on the substrate 2. The hard coating layer 3 is formed of a material containing a (meth)acrylate resin as a component of urethane (meth)acrylate, a hindered amine light stabilizer, and a UV absorber. Furthermore, relative to 100.0 parts by weight of the (meth)acrylate resin, the proportion of the hindered amine light stabilizer is 2.0 parts by weight or more and 15.0 parts by weight or less, and the proportion of the UV absorber is 5.0 parts by weight or more and 30.0 parts by weight or less.

[0045] As described above, in the hard coating 3, the (meth)acrylate resin contains urethane (meth)acrylate as a component. This gives the hard coating 3 flexibility and helps prevent cracks from appearing in the hard coating 3 when the outer window film 1 is wound into a roll.

[0046] In addition, the hard coating 3 contains a hindered amine light stabilizer, which helps to improve the light resistance of the outer window film 1 and helps to suppress the decrease in the transparency of the outer window film 1.

[0047] Furthermore, since the hard coating 3 contains an ultraviolet absorber, it can block ultraviolet rays. As a result, the proportion of ultraviolet rays in the light transmitted through the outer window film 1 can be reduced. In addition, when the outer window film 1 is adhered to the substrate, ultraviolet rays can be blocked by the hard coating 3 as the outermost layer. This also helps to suppress the deterioration of the adhesive layer 4 and the substrate 2.

[0048] In addition, relative to 100.0 parts by weight of (meth)acrylate resin, the proportion of hindered amine light stabilizer is 2.0 parts by weight or more and 15.0 parts by weight or less, and the proportion of ultraviolet absorber is 5.0 parts by weight or more and 30.0 parts by weight or less.

[0049] The hard coating 3 contains a predetermined proportion of hindered amine light stabilizer and ultraviolet absorber, thereby ensuring the transparency of the outer window film 1 while preventing cracks from appearing in the hard coating 3 when it is rolled into a roll, thus improving the weather resistance of the outer window film 1.

[0050] When the outer window film 1 has the above-described structure, the preferred effects of the present invention can be obtained; when the outer window film 1 does not have the above-described structure, the preferred effects of the present invention cannot be obtained.

[0051] For example, if the (meth)acrylate resin constituting the hard coating does not contain urethane (meth)acrylate as a component, then when the outer window film is wound into a roll, it will not be able to adequately prevent the hard coating from cracking.

[0052] Furthermore, if the hard coating does not contain hindered amine light stabilizers, the light resistance of the outer window film will be significantly reduced, and the transparency of the outer window film 1 will be significantly reduced.

[0053] Furthermore, even if the hard coating contains hindered amine light stabilizers, if the proportion is less than the aforementioned lower limit, the lightfastness of the outer window film cannot be sufficiently improved even if the hard coating contains a high content of UV absorbers. As a result, the reduction in the transparency of the outer window film 1 cannot be adequately suppressed.

[0054] Furthermore, if the proportion of hindered amine light stabilizer in the hard coating exceeds the above-mentioned upper limit, there is a concern that the hindered amine light stabilizer may segregate on the surface and the outer window film may have an undesirable appearance.

[0055] Furthermore, if the hard coating does not contain UV absorbers, the weather resistance of the exterior window film will be significantly reduced.

[0056] Furthermore, even if the hard coating contains UV absorbers, if the proportion is less than the aforementioned lower limit, the weather resistance of the outer window film cannot be adequately improved even if the hard coating contains a high content of hindered amine light stabilizers.

[0057] In addition, if the proportion of UV absorber in the hard coating exceeds the above-mentioned upper limit, the urethane (meth)acrylate will excessively absorb UV light during the curing reaction, which may lead to poor curing of the urethane (meth)acrylate.

[0058] [1-1] Substrate

[0059] The substrate 2 has the function of supporting the hard coating 3 and the adhesive layer 4.

[0060] The substrate 2 can be made of any material. For example, the constituent materials of the substrate 2 include various resin materials. However, the substrate 2 is preferably made of a material containing polyester, and more preferably mainly made of polyester.

[0061] As a result, the operability of the outer window film 1 is improved, and the bonding operation between the outer window film 1 and the substrate is more convenient. In addition, the durability of the outer window film 1 is improved.

[0062] In addition, in this specification, "main" refers to the part with the highest content among the target parts.

[0063] In particular, the polyester content in the substrate 2 is preferably 90 wt% or more, and more preferably 95 wt% or more.

[0064] The polyester constituting the substrate 2 can be, for example, polyethylene terephthalate, polybutylene terephthalate, etc. Among them, polyethylene terephthalate is preferred.

[0065] As a result, the operability of the outer window film 1 becomes better, and the bonding operation of the outer window film 1 to the substrate is more convenient. In addition, the durability of the outer window film 1 is improved. Furthermore, the adhesion to the hard coating layer 3 and the adhesive layer 4 made of the materials described later is improved.

[0066] Substrate 2 may contain components other than those listed below.

[0067] Such components include, for example, colorants, antioxidants, UV 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.

[0068] The substrate 2 preferably contains an ultraviolet absorber. This improves the lightfastness of the substrate 2 itself, and also improves the overall lightfastness of the outer window film 1. Furthermore, the ultraviolet absorber in the substrate 2 and the ultraviolet absorber in the hard coating 3 can be the same or different, but are preferably different. This allows the aforementioned effects to be achieved more significantly.

[0069] In particular, the preferred substrate 2 is mainly composed of polyethylene terephthalate and contains ultraviolet absorbers. This allows the aforementioned effects to be achieved more significantly.

[0070] Examples of ultraviolet (UV) absorbers include: salicylic acid UV absorbers such as p-butylphenyl salicylate and p-octylphenyl salicylate; benzophenone UV absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, and bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane; benzotriazole UV absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-phenol]; and 2-p-nitrophenyl-3,1-benzoxazine-4-one, 2-(p-benzoylphenyl)-3,1-benzoxazine-4-one. Benzooxazinone-based UV absorbers include ketones, 2-(2-naphthyl)-3,1-benzoxazin-4-one, 2,2'-(p-phenylene)bis(3,1-benzoxazin-4-one), 2,2'-(2,6-naphthylene)bis(3,1-benzoxazin-4-one), etc.; inorganic UV absorbers include titanium dioxide, cerium oxide, zinc oxide, iron oxide, barium sulfate, etc. For example, combinations of one or more of these can be used. Benzooxazinone-based UV absorbers are preferred from the viewpoint of being able to be melt-mixed with polyethylene terephthalate. Examples of benzooxazinone (organic) UV absorbers include 2,2'-(1,4-phenylene)bis[4H-3,1-benzoxazin-4-one] and 2,6-naphthylbis(1,3-benzoxazin-4-one).

[0071] The substrate 2 can have a generally uniform composition or it can have portions with different compositions. For example, the substrate 2 can be a laminate comprising multiple layers, each layer having portions with different compositions (including, for example, resin materials with different molecular weights). Furthermore, the substrate 2 can be made of a gradient material whose composition varies along the thickness direction.

[0072] The substrate 2 can be surface treated to improve its adhesion to the hard coating 3 and the adhesive layer 4.

[0073] Examples of such surface treatments include corona treatment and the application of adhesive resins.

[0074] Examples of easy-to-bond resins include polyester resins, polyurethane resins, and acrylic resins.

[0075] 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 20 μm or more and 100 μm or less.

[0076] As a result, the durability of the outer window film 1 is improved, and its operability is enhanced, making it easier to perform operations such as pasting onto the substrate. Furthermore, its ability to follow the shape of curved substrates is improved, effectively preventing wrinkles from forming in the outer window film 1.

[0077] [1-2] Hard coating

[0078] The hard coating 3 has better abrasion resistance than the substrate 2, for example, it has the function of improving the overall abrasion resistance of the outer window film 1.

[0079] Therefore, after the outer window film 1 is adhered to the substrate, it exhibits excellent abrasion resistance. In particular, the outer window film 1 has a high chance of coming into contact with and colliding with sand, dust, and various flying objects, and the hard coating 3 is an important part that ensures that it is difficult to scratch and has sufficient durability even in such usage environments. In addition, it can effectively prevent damage during the process of adhering the outer window film 1 to the substrate.

[0080] Furthermore, the hard coating 3 is formed of a material containing hindered amine light stabilizers and ultraviolet absorbers. This allows it to block ultraviolet rays, reducing the proportion of ultraviolet light in the light transmitted through the outer window film 1. Additionally, when the outer window film 1 is adhered to an object, the hard coating 3, as the outermost layer, can block ultraviolet rays. Therefore, the hard coating 3 helps to inhibit the deterioration of the adhesive layer 4 and the substrate 2, and also improves the weather resistance of the outer window film 1.

[0081] [1-2-1](Meth)acrylate resin

[0082] The hard coating 3 contains a (meth)acrylate resin with urethane (meth)acrylate as a constituent component, i.e., a polymerizable component.

[0083] By including urethane (meth)acrylate as a component in the (meth)acrylate resin, the hard coating 3 can be imparted with flexibility. In particular, by satisfying the specified content relationship between the hindered amine light stabilizer and the ultraviolet absorber described later, the hard coating 3 can be imparted with flexibility, and cracking of the hard coating 3 can be effectively prevented.

[0084] Carbamate (meth)acrylates are oligomers having at least a (meth)acryloyl group and a carbamate bond, and have the property of being polymerized and cured by energy radiation.

[0085] The (meth)acrylate resin constituting the hard coating 3 may contain components other than urethane (meth)acrylates. Examples of such components include (meth)acrylates that do not have urethane groups.

[0086] The proportion of urethane (meth)acrylate in the (meth)acrylate resin constituting the hard coating 3 is preferably 10.0 wt% or more, more preferably 30.0 wt% or more, and even more preferably 50.0 wt% or more.

[0087] Chapter 0061

[0088] The content of (meth)acrylate resin in the hard coating 3 is preferably 50.0 wt% or more and 93.0 wt% or less, more preferably 60.0 wt% or more and 90.0 wt% or less, and even more preferably 70.0 wt% or more and 86.0 wt% or less.

[0089] In addition, when the hard coating 3 contains multiple (meth)acrylate resins, the content of (meth)acrylate resins in the hard coating 3 is the sum of these contents.

[0090] [1-2-2] Hindered amine light stabilizers

[0091] Hard coating 3 contains hindered amine light stabilizer.

[0092] First, the role of hindered amine light stabilizers will be explained.

[0093] That is, hindered amine light stabilizers have the effect of returning the energy state of substances excited by ultraviolet irradiation to the ground state and releasing the returned energy in the form of heat.

[0094] Therefore, it can suppress chemical reactions caused by substances excited by ultraviolet radiation, thereby effectively suppressing weather resistance degradation such as yellowing of the outer window film 1.

[0095] The hindered amine light stabilizer contained in the hard coating 3 has the function of improving the weather resistance of the hard coating 3 and inhibiting the deterioration of properties over time caused by light irradiation, etc.

[0096] Hindered amine light stabilizers have at least one group (hindered amine group) represented by the following formula (1) in one molecule.

[0097] [Chemical Formula 1]

[0098]

[0099] In equation (1), R 1 This indicates a hydrogen atom, an alkyl group, or an alkoxy group. Examples of alkyl groups include methyl, ethyl, propyl, butyl, etc. Examples of alkoxy groups include methoxy and ethoxy.

[0100] When a molecule contains multiple groups represented by formula (1), the R in the multiple groups 1 They can be the same or different.

[0101] Examples of such hindered amine light stabilizers include dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine condensate, poly{[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidinyl))imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidinyl)imino], poly{[6- Morpholino-s-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidinyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidinyl)imino, N,N',N”,N”'-tetra(4,6-bis(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)triazine-2-yl)-4,7-diazadecane-1,10-diamine, bis(1,2,2, 6,6-Pentamethyl-4-piperidinyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, the reaction product of cyclohexane and n-butyl peroxide, 2,2,6,6-tetramethyl-4-piperidinamine-2,4,6-trichloro-1,3,5-triazine and 2-aminoethanol, bis(2,2,6,6-tetramethyl-1-(octoxy)-4-piperidinyl) sebacate, 1,1-di The reaction products of methyl ethyl hydroperoxide with octane, mixtures of bis(1,2,2,6,6-pentamethyl-piperidinyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate, mixtures of bis(1,2,2,6,6-pentamethyl-piperidinyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, etc. They can be used alone or in combination of two or more.

[0102] From the perspective of its excellent performance as a light stabilizer and improved weather resistance, R in formula (1) is preferred. 1 It is an alkyl tertiary hindered amine group. Hindered amine light stabilizers with tertiary hindered amine groups have particularly excellent performance as light stabilizers, making the above effects even more significant.

[0103] Examples of such hindered amine light stabilizers include: N,N',N”,N”'-tetra(4,6-bis(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-piperidinyl))amino)triazine-2-piperidinyl)-4,7-diazadecane-1,10-diamine, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-piperidinyl) sebacate and mixtures of methyl 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate, etc.

[0104] Examples of such hindered amine light stabilizers include the commercially available product manufactured by BASF under the trade name "Tinuvin 292" (a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate).

[0105] As described above, in the hard coating 3, the hindered amine light stabilizer is present in a proportion of 2.0 parts by weight or more and 15.0 parts by weight or less relative to 100.0 parts by weight of (meth)acrylate resin. The proportion of the hindered amine light stabilizer relative to 100.0 parts by weight of (meth)acrylate resin is preferably 3.0 parts by weight or more and 14.0 parts by weight or less, more preferably 4.0 parts by weight or more and 12.0 parts by weight or less, and even more preferably 5.0 parts by weight or more and 10.0 parts by weight or less.

[0106] Therefore, the effects of the present invention can be more significantly achieved.

[0107] The content of the hindered amine light stabilizer in the hard coating 3 is preferably 1.5 wt% or more and 12.5 wt% or less, more preferably 2.2 wt% or more and 11.5 wt% or less, and even more preferably 4.0 wt% or more and 8.3 wt% or less.

[0108] Therefore, the effects of the present invention can be more significantly achieved.

[0109] In addition, when the hard coating 3 contains a variety of hindered amine light stabilizers, the content of the hindered amine light stabilizers in the hard coating 3 is the sum of these contents.

[0110] [1-2-3] Ultraviolet absorbers

[0111] Hard coating 3 contains UV absorbers.

[0112] Ultraviolet absorbers absorb ultraviolet rays and convert them into energy such as heat, thus preventing the effects of ultraviolet rays on the human body and objects.

[0113] The ultraviolet absorber is preferably an acetonitrile solution with a concentration of 0.1 wt% having a maximum absorption wavelength of less than 380 nm in the wavelength range of 200 nm to 500 nm.

[0114] In addition, if there are multiple maximum absorption wavelengths in the wavelength range of 200nm to 500nm, at least one maximum absorption wavelength must be within the above range.

[0115] Therefore, when exposed to ultraviolet light, acrylic polymers are not hindered by ultraviolet absorbers and can be fully cured.

[0116] On the other hand, from the viewpoint of preventing the effects of ultraviolet rays on the human body and objects, the lower limit of the maximum absorption wavelength is preferably above 280nm.

[0117] Examples of compounds that can be used as ultraviolet absorbers include benzophenone, benzotriazole, benzoate esters, benzoxazinone, triazine, phenyl salicylate, cyanoacrylate, and nickel complex salts. One of these compounds can be used alone or in combination with two or more.

[0118] Among the aforementioned ultraviolet absorbers, compounds having a benzophenone structure or a hydroxyphenyltriazine structure are preferred.

[0119] These compounds exhibit excellent compatibility with the aforementioned (meth)acrylic resins and also possess high ultraviolet absorption capabilities. Therefore, the hard coating 3 formed using these compounds readily satisfies the aforementioned optical properties.

[0120] In particular, the hard coating 3 preferably contains compounds having a benzophenone structure and compounds having a hydroxyphenyltriazine structure as ultraviolet absorbers.

[0121] Therefore, the above-mentioned effects of the present invention can be more significantly realized.

[0122] When the hard coating 3 contains a compound having a benzophenone structure and a compound having a hydroxyphenyltriazine structure as an ultraviolet absorber, the ratio of the content of the compound having a benzophenone structure to the content of the compound having a benzophenone structure in the hard coating 3 is as follows: The hydroxyphenyltriazine structure is preferably 1.0:2.0 or more and 2.0:1.0 or less, more preferably 1.0:1.5 or more and 1.0:1.0 or less, and even more preferably 1.0:1.2 or more and 1.2:1.0 or less.

[0123] As a result, the aforementioned effects are realized even more significantly.

[0124] Specific examples of ultraviolet absorbers include compounds represented by formulas (2) to (13) below. Among these, compounds represented by formulas (8) to (13) below are preferred from the viewpoint of more significantly exerting the above-mentioned effects.

[0125] [Chemical Formula 2]

[0126]

[0127] [Chemical Formula 3]

[0128]

[0129] [Chemical Formula 4]

[0130]

[0131] [Chemical Formula 5]

[0132]

[0133] [Chemical Formula 6]

[0134]

[0135] [Chemical Formula 7]

[0136]

[0137] [Chemical Formula 8]

[0138]

[0139] [Chemical Formula 9]

[0140]

[0141] [Chemical Formula 10]

[0142]

[0143] [Chemical Formula 11]

[0144]

[0145] (In formula (11), R is an alkyl group with 10 or more carbon atoms and 12 or fewer carbon atoms)

[0146] [Chemical Formula 12]

[0147]

[0148] [Chemical Formula 13]

[0149]

[0150] Commercially available ultraviolet absorbers include, for example, those manufactured by BASF under the brand names "Tinuvin PS," "Tinuvin 460," "Tinuvin 477," "Tinuvin 400," and "Tinuvin 384-2." Other examples include commercially available products manufactured by Shipro Kasei under the brand names "SEESORB SB701," "SEESORB SB704," "SEESORB SB706," "SEESORB SB707," "SEESORB SB709," "SEESORB SB107," and "SEESORB SB106." From the viewpoint of more significantly achieving the aforementioned effects, "Tinuvin 460," "Tinuvin 477," "Tinuvin 400," "SEESORB SB107," and "SEESORB SB106" are preferred.

[0151] As described above, the hard coating 3 contains an ultraviolet absorber in a proportion of 5.0 parts by weight or more and 30.0 parts by weight or less relative to 100.0 parts by weight of (meth)acrylate resin. However, the proportion of the ultraviolet absorber relative to 100.0 parts by weight of (meth)acrylate resin is preferably 7.0 parts by weight or more and 28.0 parts by weight or less, more preferably 8.0 parts by weight or more and 25.0 parts by weight or less, and even more preferably 10.0 parts by weight or more and 20.0 parts by weight or less.

[0152] Therefore, the effects of the present invention can be more significantly achieved.

[0153] The content of ultraviolet absorber in the hard coating 3 is preferably 4.1 wt% or more and 22.7 wt% or less, more preferably 5.7 wt% or more and 21.4 wt% or less, and even more preferably 8.3 wt% or more and 16.0 wt% or less.

[0154] Therefore, the effects of the present invention can be more significantly achieved.

[0155] In addition, when the hard coating 3 contains multiple ultraviolet absorbers, the content of ultraviolet absorbers in the hard coating 3 is the sum of these contents.

[0156] [1-2-4] Other ingredients

[0157] Hard coating 3 may also contain components other than those mentioned above. In the following text, such components will also be referred to as "other components" in this section.

[0158] Examples of such components include resin components other than the aforementioned (meth)acrylate resins, light stabilizers other than hindered amine light stabilizers, antioxidants, silane coupling agents, leveling agents, antistatic agents, defoamers, etc.

[0159] The proportion of other components in the hard coating 3 is preferably 10 wt% or less, more preferably 5 wt% or less, and even more preferably 3 wt% or less.

[0160] [1-2-5] Other conditions

[0161] The thickness of the hard coating 3 is not particularly limited, but is preferably 0.1 μm or more and 20 μm or less, more preferably 0.2 μm or more and 15 μm or less, and even more preferably 0.4 μm or more and 10 μm or less.

[0162] As a result, the hard coating 3 can be prevented from becoming too hard, and better wear resistance can be obtained. It can also improve the adhesion to the substrate and the operability of the external window film 1 application. In addition, it can appropriately prevent the generation of cracks, etc.

[0163] [1-3] Adhesive layer

[0164] The adhesive layer 4 typically has excellent flexibility and is the part that is tightly bonded to the substrate.

[0165] Examples of adhesives constituting adhesive layer 4 include acrylic adhesives, natural rubber adhesives, synthetic rubber adhesives, polyvinyl ether adhesives, polyurethane adhesives, and silicone adhesives. Among these, acrylic adhesives, polyurethane adhesives, and silicone adhesives are particularly preferred from the viewpoint of weather resistance.

[0166] Specific examples of synthetic rubber adhesives include styrene-butadiene rubber, polyisobutylene rubber, isobutylene-isoprene, styrene-isoprene block copolymers, styrene-butadiene block copolymers, and styrene-ethylene-butene block copolymers.

[0167] Specific examples of acrylic adhesives include copolymers of butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, methyl (meth)acrylate, hydroxyethyl (meth)acrylate, and (meth)acrylates, wherein two or more of the various polymerizing components, such as hydroxybutyl acrylate, are polymerized.

[0168] Specific examples of polyvinyl ether adhesives include polyvinyl ether, polyvinyl isobutyl ether, etc.

[0169] Specific examples of silicone adhesives include dimethylpolysiloxane, etc.

[0170] These adhesives can be used alone or in combination of two or more.

[0171] The adhesive layer 4 can be mainly composed of adhesive, or it can contain other components besides adhesive.

[0172] Such components include, for example, UV absorbers, thickeners, fillers, softeners, antioxidants, light stabilizers, crosslinking agents, colorants, modifiers, rust inhibitors, flame retardants, and hydrolysants. Examples include inhibitors, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, antistatic agents, polymerization inhibitors, catalysts, leveling agents, thickeners, dispersants, and defoamers.

[0173] The thickness of the adhesive layer 4 is not particularly limited, but 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.

[0174] As a result, the durability of the outer window film 1 is improved, and its operability is enhanced, making it easy to apply to the substrate. Furthermore, its ability to follow the shape of curved substrates is improved, effectively preventing wrinkles from forming in the outer window film 1.

[0175] [1-4] Other conditions

[0176] The thickness (total thickness) of the outer window film 1 is not particularly limited, but is preferably 11 μm or more and 400 μm or less, more preferably 18 μm or more and 230 μm or less, and even more preferably 20 μm or more and 100 μm or less.

[0177] As a result, the durability and UV absorption function of the outer window film 1 are improved, and the operability of the outer window film 1 is enhanced, making operations such as attaching to the substrate easier. In addition, the ability to follow the shape of curved substrates is improved, effectively preventing wrinkles from forming in the outer window film 1.

[0178] Here, "total thickness" refers to the total thickness of the outer window film 1 when it is adhered to the substrate. Therefore, for example, even if the release liner 10 (described later) is placed on the adhesive layer 4 during the storage of the outer window film 1, the thickness of the release liner 10 is not included in the total thickness of the outer window film 1.

[0179] In order not to damage the appearance of the object being adhered to, the outer window film 1 is preferably transparent.

[0180] In this specification, "transparent" means that the transmittance of visible light is 60% or more (up to 100%), preferably 80% or more (up to 100%). The transmittance of the exterior window film 1 can be measured according to the method of JIS A5759:2016 (films for architectural windows - test for visible light transmittance).

[0181] The yellowness index (YI) of the outer window film 1 is preferably 4 or less, more preferably 1 or more and 3.5 or less, and even more preferably 1.5 or more and 2.5 or less.

[0182] As a result, an outer window film 1 with suppressed coloration is obtained. Thus, the outer window film 1 can achieve excellent transparency and colorlessness, making it suitable for use as an outer window film.

[0183] It should be noted that the yellow index (YI) of the outer window film 1 can be measured according to the method in JIS K 7373:2006.

[0184] The haze of the outer window film 1, as measured according to JIS K 7136:2000, is preferably close to the haze of the substrate 2 alone, preferably 2.0% or less, more preferably 1.8% or less, and even more preferably 1.5% or less.

[0185] Therefore, the outer window film 1 can have excellent transparency.

[0186] [2] Peeling off the gasket

[0187] A release liner 10 can be provided on the adhesive layer 4 of the outer window film 1.

[0188] When the outer window film 1 is applied to the object, the release liner 10 is peeled off from the adhesive layer 4.

[0189] The release liner 10 is not particularly limited and can have a structure commonly used in the window film industry. As a component of the release liner 10, for example, it can be configured such that a release layer is provided on the surface of a paper substrate or a resin film substrate.

[0190] Examples of materials constituting resin film substrates include polyethylene terephthalate and polypropylene. Examples of materials constituting paper substrates include polyethylene laminated paper, polypropylene laminated paper, clay-coated paper, resin-coated paper, cellophane, and wood pulp-free paper.

[0191] Examples of compositions containing release agents, such as silicone, long-chain alkyl resins, and fluororesins, can be used as components of the b-release layer.

[0192] The thickness of the release liner 10 is not particularly limited, but is preferably 10 μm or more and 400 μm or less. Furthermore, when the release liner 10 has the aforementioned release layer, the thickness of the release layer is preferably, for example, 0.01 μm or more and 5 μm or less.

[0193] [3] Manufacturing method of window film

[0194] Next, the method for manufacturing the external window film will be explained.

[0195] First, for example, a liquid composition (coating liquid) for forming the hard coating 3 is applied to one side of the substrate 2 to form the hard coating 3. Next, a liquid composition (coating liquid) for forming the adhesive layer 4 is applied to the other side of the substrate 2 to form the adhesive layer 4. Thus, the outer window film 1 can be manufactured. In such a method, the order in which the hard coating 3 and the adhesive layer 4 are formed is not particularly limited.

[0196] The liquid composition used to form the hard coating 3 can be applied by known methods, such as bar coating, blade coating, roller coating, knife coating, mold coating, gravure coating, etc.

[0197] The adhesive layer 4 can be formed by irradiating the liquid composition coated on the substrate 2 with ultraviolet light or an electron beam, or by heating and curing it.

[0198] In the liquid composition used to form the hard coating 3, from the viewpoint of shortening the polymerization time caused by light irradiation and reducing the amount of light irradiation to form the hard coating 3, it is preferable to add the above-mentioned photopolymerization initiator.

[0199] In other words, the (meth)acrylate resin preferably has a structure for polymerizing urethane (meth)acrylate using the aforementioned photopolymerization initiator.

[0200] The content of the photopolymerization initiator in the liquid composition for forming the hard coating 3 is preferably 0.05 parts by mass and 15.0 parts by mass and less, more preferably 0.1 parts by mass and 10.0 parts by mass and less, and even more preferably 0.3 parts by mass and 5.0 parts by mass and less, relative to 100.0 parts by mass of urethane (meth)acrylate.

[0201] As a result, the aforementioned effects are made even more pronounced.

[0202] The liquid composition used to form the hard coating 3 may contain components other than those described above, as needed. Such components may include, for example, a thermosetting catalyst, a solvent, etc.

[0203] The liquid composition for forming the adhesive layer 4 can be obtained by dissolving or suspending the aforementioned materials constituting the adhesive layer 4 in a suitable solvent. Examples of solvents include esters such as ethyl acetate and butyl acetate; aromatic hydrocarbons such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; and aromatic hydrocarbons such as toluene and xylene. A composition selected from one or two of these solvents can be used.

[0204] The liquid composition used to form the adhesive layer 4 can be applied by known methods, such as air knife coating machines, doctor blade coating machines, bar coating machines, gravure coating machines, roller coating machines, roller knife coating machines, curtain coating machines, die coating machines, knife coating machines, screen coating machines, Meyer bar coating machines, kiss coating machines, and other methods of various coating machines.

[0205] The amount of liquid composition used to form adhesive layer 4 can be appropriately adjusted so that the thickness of the dried adhesive layer 4 falls within the aforementioned range. There are no particular limitations on the drying conditions of the liquid composition used to form adhesive layer 4, but the drying temperature can be, for example, above 70°C and below 130°C, and the drying time can be, for example, 1 minute and below 5 minutes.

[0206] Thus, the outer window film 1 can be obtained.

[0207] In addition, a release liner 10 can be laminated onto the adhesive layer 4 of the outer window film 1.

[0208] [4] Adhesive

[0209] Next, the object to which the outer window film 1 is pasted will be described.

[0210] External window film 1 is suitable for use in the windows of residential buildings, high-rise buildings, automobiles, trains and other vehicles.

[0211] Specifically, the exterior window film 1 of the present invention is applied to the exterior surface of a window glass. In such an exterior window film 1, sunlight sequentially irradiates the hard coating 3 / substrate 2 / adhesive layer 4 / window glass / interior. Therefore, the hard coating 3 can block ultraviolet rays and appropriately suppress its degradation. In addition, it can also appropriately suppress the degradation of the substrate 2 and adhesive layer 4 caused by ultraviolet rays. Furthermore, in addition to ultraviolet rays, it can also appropriately suppress degradation caused by rain, wind, temperature changes, etc.

[0212] As mentioned above, since the outer window film 1 has excellent weather resistance, it can be used as an outer window film in harsher working environments than the inner window film.

[0213] [5] How to apply window film

[0214] Next, the method for applying the outer window film 1 will be explained.

[0215] The following describes the process of attaching the exterior window film 1 to a substrate such as window glass. When the exterior window film 1 has a release liner 10, the release liner 10 is first peeled off to expose the adhesive layer 4. The exterior window film 1 can be adhered to the substrate by bonding the adhesive layer 4 to it. This adhesion can be performed, for example, by a method known as water bonding. In water bonding, the adhesive layer 4 and the substrate are bonded by inserting a construction liquid containing a surfactant added to water at the interface between the adhesive layer 4 and the substrate, and then the application is completed by scraping out the construction liquid using a jig called a scraper.

[0216] The preferred embodiments of the present invention have been described above, but the present invention is not limited thereto.

[0217] For example, the external window film may have a structure other than those described above. More specifically, for example, at least one intermediate layer may be provided between the substrate and the adhesive layer or between the substrate and the hard coating layer, or at least one coating layer may be provided on the outer surface of the hard coating layer.

[0218] Furthermore, the outer window film of the present invention can be manufactured by any method, and is not limited to the manufacturing methods described above.

[0219] For example, the external window film of the present invention can be formed by applying a transfer printing method. Specifically, firstly, a composition for forming an adhesive layer is applied to one side of a release liner to form an adhesive layer. Then, the release liner with the adhesive layer is bonded to a substrate. In this way, the external window film can be formed by applying a transfer printing method.

[0220] [example]

[0221] The present invention will now be described in detail with reference to specific embodiments, but the present invention is not limited thereto. In the following embodiments, all processing and measurements without specified temperature conditions were performed at room temperature (23°C).

[0222] [6] External window film manufacturing

[0223] (Example 1)

[0224] First, a liquid composition (coating liquid) for forming a hard coating was prepared using beamset 575CB (manufactured by Arakawa Chemical Industry Co., Ltd.) containing polyurethane acrylate, Tinuvin 292 (manufactured by BASF) as a hindered amine light stabilizer, UV-24 (manufactured by Solvay) as a benzophenone-based ultraviolet absorber, Tinuvin 477 (manufactured by BASF) as an ultraviolet absorber, Omnira d TPO (manufactured by IGM Resins) as a photopolymerization initiator, and methyl ethyl ketone as a solvent.

[0225] Additionally, Tinuvin 292 is a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate.

[0226] [Chemical Formula 14]

[0227]

[0228] In addition, UV-24 is 2,2'-dihydroxy-4-methoxybenzophenone.

[0229] [Chemical Formula 15]

[0230]

[0231] Additionally, Tinuvin 477 is a mixture of a hydroxyphenyltriazine UV absorber and 2-methoxy-1-methylethyl acetate. Furthermore, Omnirad TPO is 2,4,6-trimethylbenzoyl diphenylphosphine oxide, with the structure shown below.

[0232] [Chemical Formula 16]

[0233]

[0234] The liquid composition for forming a hard coating as described above was applied to one side of a substrate using a rod coating method, while adjusting the coating amount to achieve a cured film thickness of 2.5 μm, thus obtaining the coating film. The cumulative light intensity of the coating film under irradiation was 200 mJ / cm. 2 Ultraviolet light. This forms a hard coating.

[0235] As the substrate, a 50μm thick polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., Toyobo Ester (registered trademark) HB3) containing ultraviolet absorbers was used.

[0236] Next, an acrylic adhesive (100 parts by mass of a copolymer of 90 parts by mass of butyl acrylate and 10 parts by mass of acrylic acid (weight average molecular weight: 600,000), and 1 part by mass of an isocyanate crosslinking agent) is applied to the surface of the substrate opposite to the surface where the hard coating is formed, to obtain a coating film with a dried thickness of 25 μm. The coating film is dried at 100°C for 1 minute to form an adhesive layer. An exterior window film is manufactured in this manner. Furthermore, a release liner with a thickness of 38 μm is laminated onto the adhesive layer of the exterior window film.

[0237] (Examples 2 and 3)

[0238] Except for changing the amount of each component in the liquid composition for forming the hard coating so that the content of each component satisfies the relationship shown in Table 1, the external treatment is performed in the same manner as in Example 1. External window film is then produced.

[0239] (Comparative Examples 1-6)

[0240] Except for changing the amount of each component in the liquid composition for forming the hard coating so that the content of each component satisfies the relationship shown in Table 1, the external treatment is performed in the same manner as in Example 1. External window film is then produced.

[0241] [7] Evaluation of external window film

[0242] The obtained external window film is evaluated as follows.

[0243] [7-1] Weather resistance test of hard coating

[0244] Accelerated aging tests were conducted using an accelerated aging tester.

[0245] The obtained external window film was attached to a glass plate and placed in an accelerated aging test chamber, where it was exposed to an irradiance of 255 W / m². 2 Accelerated aging tests were conducted under conditions of (300-400nm), blackboard temperature of 63℃, and humidity, during which the samples were placed for 1000 hours.

[0246] Visually inspect the surface of the hard coating to evaluate for the presence of cracks.

[0247] A: No cracks

[0248] B: There are cracks

[0249] [7-2] Crack resistance test of hard coating

[0250] The obtained outer window film is wound into a roll around a cylindrical core with an outer diameter of 20 mm, so that the hard coating is on the outside.

[0251] Remove the core from the core, insert the needle 10mm into the hard coating, visually inspect the damaged surface, and evaluate whether there are cracks.

[0252] A: No cracks

[0253] B: There are cracks

[0254] [7-3] External window film haze

[0255] According to JIS K7136:2000, the haze of the obtained external window film was measured using a haze meter (manufactured by Nippon Denshoku Kogyo, NDH-5000).

[0256] It can be said that the smaller this value is, the better the transparency of the outer window film.

[0257] Table 1 summarizes the conditions for forming the hard coating composition and the results of the above evaluations of the various examples and comparative examples. In Table 1, the content of each component is expressed in parts by mass. Furthermore, the content of the hindered amine light stabilizer and the ultraviolet absorber is expressed as a percentage relative to 100.0 parts by mass of urethane acrylate contained in the formed hard coating. Furthermore, the content of the photopolymerization initiator is expressed as a percentage relative to 100.0 parts by mass of urethane (meth)acrylate contained in the liquid composition for forming the hard coating.

[0258] Table 1

[0259]

[0260] As shown in Table 1, in Examples 1 to 3, the hard coating achieved good results in terms of weather resistance, crack resistance, and haze.

[0261] On the other hand, no satisfactory results were obtained in any of the comparative examples.

[0262] More specifically, in Comparative Examples 2-4, where the hard coating did not contain hindered amine light stabilizers, cracks appeared and haze increased after the weathering test. Furthermore, in Comparative Example 1, which did not contain either hindered amine light stabilizers or UV absorbers, the haze became even greater. Additionally, even when both hindered amine light stabilizers and UV absorbers were present, Comparative Examples 5 and 6, with a low content of hindered amine light stabilizers, did not yield sufficiently good results.

[0263] In addition, surface micrographs of the external window films of Example 1 and Comparative Examples 1, 3, and 6 after undergoing a 1000-hour accelerated aging test are shown in the figures below. Figure 2 , 3 , 4 and 5.

[0264] also, Figure 6 A surface micrograph of the outer window film of Comparative Example 1 is shown before accelerated aging testing.

[0265] Although no cracks were observed in Example 1, cracks were found in Comparative Examples 1, 3 and 6.

[0266] When preparing the liquid composition for forming a hard coating, the hindered amine light stabilizer is in the ratio of 2.0 parts by mass to 100.0 parts by mass of (meth)acrylate resin in the formed hard coating, and the proportion of ultraviolet absorber in the liquid composition for forming the hard coating can vary within a range of 5.0 parts by mass or more and 30.0 parts by mass or less. Various changes can be made to the proportions of the hindered amine light stabilizer and the ultraviolet absorber in the acrylate resin, and by manufacturing an external window film of the same type as the aforementioned external window film and testing and evaluating it to the same specifications, the same results as described above can still be obtained.

[0267] Furthermore, the mixing ratio of the UV absorber (UV-24) with a benzophenone structure and the UV absorber (Tinuvin 477) with a hydroxyphenyl triazine structure in the hard coating was varied in various ways within the range of 1.0:2.0 to 2.0:1.0 by mass. Except for various changes within the range of 0 to 2.0:1.0, the same results could still be obtained by manufacturing an external window film of the same type as the above-mentioned external window film and testing and evaluating it with the same specifications.

[0268] In addition, by varying the thickness of the hard coating within the range of 0.1μm to 20μm, and by manufacturing an external window film of the same type as the aforementioned external window film and testing and evaluating it according to the same specifications, the same results as described above can still be obtained.

[0269] [Industrial Applicability]

[0270] According to the present invention, an exterior window film equipped with a hard coating is provided that ensures transparency, prevents cracking in the hard coating during winding, and exhibits excellent weather resistance. Therefore, the present invention has industrial applicability.

Claims

1. An external window film, characterized in that: It includes a substrate, a hard coating disposed on one side of the substrate, and an adhesive layer disposed on the side opposite to the hard coating side of the substrate. The hard coating is composed of a (meth)acrylate resin containing urethane (meth)acrylate as a component, a hindered amine light stabilizer, and an ultraviolet absorber. Relative to 100.0 parts by weight of (meth)acrylate resin, the proportion of hindered amine light stabilizer is 5.0 parts by weight or more and 15.0 parts by weight or less, and the proportion of ultraviolet absorber is 5.0 parts by weight or more and 30.0 parts by weight or less.

2. The external window film according to claim 1, wherein a compound having a benzophenone structure and a compound having a hydroxyphenyltriazine structure are used as the ultraviolet absorber.

3. The external window film according to claim 2, wherein, The ratio of the content of the compound having a benzophenone structure to the content of the compound having a hydroxyphenyltriazine structure in the hard coating is greater than 1.0:2.0 and less than 2.0:1.

0.

4. The external window film according to any one of claims 1 to 3, wherein, The (meth)acrylate resin is formed by polymerizing the urethane (meth)acrylate using a photopolymerization initiator.

5. The external window film according to claim 4, wherein, The photopolymerization initiator is a triphenylphosphine oxide compound.

6. The external window film according to claim 1, wherein the thickness of the hard coating is 0.1 μm or more and 20 μm or less.

7. The external window film according to claim 1, wherein, The substrate is made of a material containing polyester.

8. The external window film according to claim 1, wherein, The proportion of the hindered amine light stabilizer is 10.0 parts by weight or more and 15.0 parts by weight or less, relative to 100.0 parts by weight of the (meth)acrylate resin.

9. The external window film according to claim 1, wherein, The proportion of the ultraviolet absorber is 10.0 parts by weight or more and 30.0 parts by weight or less relative to 100.0 parts by weight of the (meth)acrylate resin.

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