Hard coat film and decorative sheet using the same

Abstract

The present invention provides a hard coat film with excellent light resistance and a decorative sheet using the same. [Solution] The invention comprises a substrate made of polyethylene terephthalate and a hard coat layer (HC layer) laminated on the outermost layer of one side of the substrate, with an easy-adhesion layer further provided between the HC layer and the substrate. The HC layer is a cured product of a composition containing a specific compound UV-curable resin, a photopolymerization initiator, and a UV absorber, with the compound content being 3-7% by mass of the HC layer, and the thickness of the HC layer being 4-6 μm. The test was conducted using an accelerated lightfastness tester at 62°C and 75 mW / cm². 2 The absolute value of the change in luminous transmittance Y before and after 24 hours of UV irradiation is 0.30 or less, and the hue a * The absolute value of the change is 0.20 or less, hue b * A hard coat film in which the absolute value of the change is 0.48 or less, and the number of sections remaining on the substrate in a cellophane tape adhesion test using a 2mm grid method is 50 or more out of 100 squares.

Description

[Technical Field]

[0001] This invention relates to a light-resistant hard coat film and a decorative sheet using the same. [Background technology]

[0002] Decorative sheets, made by printing wood grain, stone patterns, etc., onto resin films or paper, are widely used as materials to decorate the surfaces of furniture and building materials. One type of decorative sheet consists of a hard coat film, which is made by laminating a hard coat layer onto a base film such as PET (polyethylene terephthalate) film, and this hard coat film is placed on the front side of the printed layer for surface protection. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-43374 [Patent Document 2] Patent No. 5605587 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] PET film is susceptible to degradation from ultraviolet light. In a configuration where a hard coat film based on PET film is applied to a decorative sheet, yellowing due to degradation of the PET film leads to a deterioration in the appearance of the decorative sheet.

[0005] Therefore, in order to improve the light resistance of the hard coat film provided on the decorative sheet, it has been conventional practice to add light-resistant agents such as ultraviolet absorbers to the hard coat layer (see, for example, Patent Documents 1 and 2). However, conventional hard-coated films with ultraviolet absorbers added to the hard coat layer still had room for improvement in terms of light resistance.

[0006] Therefore, an object of the present invention is to provide a hard coat film having excellent light resistance and a decorative sheet using the same.

Means for Solving the Problems

[0007] The hard coat film according to the present invention includes a base material made of polyethylene terephthalate and a hard coat layer laminated on the outermost layer on one surface side of the base material, and further includes an easy adhesion layer between the hard coat layer and the base material. The hard coat layer is a cured product of a composition containing an ultraviolet curable resin, a photoinitiator, and an ultraviolet absorber (however, a hindered amine compound is not included). The ultraviolet absorber is composed of a hydroxyphenyltriazine compound having a maximum absorption wavelength at 280 to 330 nm, and its content is 3 to 7% by mass of the hard coat layer. The thickness of the hard coat layer is 4 to 6 μm. Using a super accelerated light resistance tester (manufactured by Iwasaki Electric Co., Ltd., model: Eye Super UV Tester), the absolute value of the change amount of the visual transmittance Y before and after a 24-hour light resistance test set under the conditions of a temperature of 62 °C and an ultraviolet irradiation amount of 75 mW / cm 2 is 0.30 or less, the absolute value of the change amount of hue a * is 0.20 or less, the absolute value of the change amount of hue b * is 0.48 or less, and after the light resistance test, the hard coat layer is subjected to a cellophane tape adhesion test by the 2 mm grid method. After forming 100 squares of 2 mm squares and adhering the cellophane tape, the cellophane tape is peeled off, and the number of sections remaining on the base material without peeling is 50 or more.

[0008] The decorative sheet according to the present invention includes the above hard coat film.

Effects of the Invention

[0009] According to the present invention, a hard coat film having excellent light resistance and a decorative sheet using the same can be provided.

Brief Description of the Drawings

[0010] [Figure 1]A schematic cross-sectional view showing the hard coat film according to the embodiment. [Figure 2] A schematic cross-sectional view showing a decorative sheet according to the embodiment. [Modes for carrying out the invention]

[0011] Figure 1 is a schematic cross-sectional view showing a hard coat film according to the embodiment, and Figure 2 is a schematic cross-sectional view showing a decorative sheet according to the embodiment.

[0012] The hard coat film 100 shown in Figure 1 comprises a transparent substrate 1 and an easy-adhesion layer 2 and a hard coat layer 3 that are sequentially laminated on one side of the transparent substrate 1. The decorative sheet 200 shown in Figure 2 is a sheet used as a surface decoration material for furniture and building materials, and comprises the hard coat film 100 shown in Figure 1. More specifically, the decorative sheet 200 is formed by laminating the other side of the transparent substrate 1 of the hard coat film 100 to a printed layer 11 provided on one side of the substrate 10 via an adhesive layer 12. The hard coat film 100 functions as a surface protective material for the decorative sheet 200.

[0013] The following provides a detailed explanation of hard coat film 100.

[0014] The transparent substrate 1 is a film made of polyethylene terephthalate (PET). PET is suitable as a substrate for the protective film of the decorative sheet 200 because it has excellent heat resistance, cold resistance, and chemical resistance, as well as high transparency. The surface of the transparent substrate 1 may be modified by corona treatment, plasma treatment, or the like.

[0015] The easy-adhesion layer 2 is provided to improve the adhesion between the transparent substrate 1 and the hard coat layer 3, and is formed, for example, by applying an anchor coating agent. However, the easy-adhesion layer 2 is not essential, and the hard coat layer 3 may be laminated directly onto the transparent substrate 1.

[0016] The hard coat layer 3 can be formed by applying and curing a hard coat layer forming composition containing an ultraviolet-curable resin, an ultraviolet absorber, a photopolymerization initiator, and a solvent.

[0017] UV-curable resins are resins that polymerize and harden upon irradiation with ultraviolet light, and for example, monofunctional, bifunctional, or trifunctional (meth)acrylate monomers can be used. In this specification, "(meth)acrylate" is a general term for both acrylate and methacrylate, and "(meth)acryloyl" is a general term for both acryloyl and methacryloyl.

[0018] Examples of monofunctional (meth)acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfluryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isobornyl (meth)acrylate. Phosphate, Isodecyl (meth)acrylate, Lauryl (meth)acrylate, Tridecyl (meth)acrylate, Cetyl (meth)acrylate, Stearyl (meth)acrylate, Benzyl (meth)acrylate, 2-Ethoxyethyl (meth)acrylate, 3-Methoxybutyl (meth)acrylate, Ethyl carbitol (meth)acrylate, Phosphate (meth)acrylate, Ethylene oxide-modified Phosphate (meth)acrylate, Phenoxy (meth)acrylate, Ethylene oxide-modified Phenoxy (meth)acrylate, Propylene oxide Phenoxy(meth)acrylate modified with ethylene oxide, nonylphenol(meth)acrylate, ethylene oxide-modified nonylphenol(meth)acrylate, propylene oxide-modified nonylphenol(meth)acrylate, methoxydiethylene glycol(meth)acrylate, methoxypolyethylene glycol(meth)acrylate, methoxypropylene glycol(meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, 2-(meth) ) Acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hexahydrohydrogen phthalate, 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropropyl (meth)acrylate, 2-adamantane,Examples include adamantane derivative mono(meth)acrylates such as adamantyl acrylate, which has a monovalent mono(meth)acrylate derived from adamantanediol.

[0019] Examples of difunctional (meth)acrylate compounds include di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and hydroxypivalate neopentyl glycol di(meth)acrylate.

[0020] Examples of trifunctional (meth)acrylate compounds include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris-2-hydroxyethyl isocyanurate tri(meth)acrylate, glycerin tri(meth)acrylate, and other trifunctional (meth)acrylate compounds such as pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, and ditrimethylolpropane tri(meth)acrylate. Examples include polyfunctional (meth)acrylate compounds with three or more functions, such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane hexa(meth)acrylate, as well as polyfunctional (meth)acrylate compounds in which some of these (meth)acrylates are substituted with alkyl groups or ε-caprolactone.

[0021] Furthermore, urethane (meth)acrylate can also be used as an ultraviolet-curing resin. Examples of urethane (meth)acrylate include those obtained by reacting a product obtained by reacting a polyester polyol with an isocyanate monomer or prepolymer with a hydroxyl group (meth)acrylate monomer.

[0022] Examples of urethane (meth)acrylates include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer.

[0023] The UV-curing resins mentioned above can be used individually or in combination of two or more types. That's good. Furthermore, the UV-curable resin mentioned above may be a monomer in the hard coat layer forming composition, or it may be a partially polymerized oligomer.

[0024] While there are no particular limitations on the UV absorber, it is preferable to use one having a maximum absorption wavelength in the 280-330 nm range. The UV absorber is added to suppress yellowing due to degradation of the PET substrate. However, if the amount of UV absorption by the UV absorber becomes too high when curing the coating film of the hard coat layer forming composition, the curing reaction will not be activated, and the UV absorber will inhibit the curing of the UV-curable resin. In this case, the curing of the UV-curable resin will be insufficient, making the coating film prone to peeling, and resulting in insufficient surface hardness of the hard coat layer 3 and poor adhesion between the hard coat layer 3 and the transparent substrate 1. Therefore, in the present invention, curing inhibition when a UV absorber is included is suppressed by using a UV absorber whose absorption wavelength range in the UV region is sufficiently narrow compared to the absorption wavelength range in the UV region of the photopolymerization initiator. As the UV absorber, the hydroxyphenyltriazine compound having a maximum absorption wavelength in the 280-330 nm range described above can be suitably used.

[0025] The amount of UV absorber added is preferably 3 to 7% by mass of the hard coat layer 3 (total solid content of the hard coat layer forming composition) after curing. If the amount of UV absorber added is less than 3% by mass of the hard coat layer 3, the UV absorption capacity of the hard coat layer 3 decreases, and the degradation of the transparent substrate 1 made of PET is not adequately suppressed. If the amount of UV absorber added exceeds 7% by mass of the hard coat layer 3, the amount of UV absorber is too high, causing curing inhibition of the UV-curable resin, resulting in insufficient adhesion and surface hardness of the hard coat layer 3.

[0026] While there are no particular limitations on the photopolymerization initiator, it is preferable to use one having an absorption wavelength range of 200 to 380 nm. When a photopolymerization initiator having an absorption wavelength range of 200 to 380 nm is used, the absorption wavelength range of the UV absorber having a maximum absorption wavelength of 280 to 330 nm is sufficiently narrow compared to the absorption wavelength range of the photopolymerization initiator. Therefore, the curing reaction of the UV-curable resin can proceed while avoiding curing inhibition by the UV absorber. Examples of photopolymerization initiators that can be used include 2,2-ethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, Michler ketone, acetophenone, and 2-chlorothioxanthone. One of these may be used alone, or two or more may be used in combination.

[0027] Examples of solvents include ethers such as dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, and phenethole; ketones such as acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone; esters such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butylolactone; and cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, and cellosolve acetate. These may be used individually or in combination of two or more types.

[0028] Furthermore, the hard coat layer formation composition may contain metal oxide fine particles for the purpose of adjusting the refractive index or imparting hardness. Examples of metal oxide fine particles include zirconium oxide, titanium oxide, niobium oxide, antimony trioxide, antimony pentoxide, tin oxide, indium oxide, indium tin oxide, and zinc oxide.

[0029] Furthermore, the hard coat layer forming composition may contain any of the following to impart water-repellent and / or oil-repellent properties and enhance stain resistance: silicon oxide, fluorine-containing silane compound, fluoroalkylsilazane, fluoroalkylsilane, fluorine-containing silicon-based compound, or perfluoropolyether group-containing silane coupling agent.

[0030] Other additives that may be added to the hard coat layer forming composition include leveling agents, defoaming agents, antioxidants, light stabilizers, photosensitizers, conductive materials, and the like.

[0031] The method for applying the hard coat layer formation composition to the transparent substrate 1 is not particularly limited, and wet coating methods such as dip coating, spin coating, flow coating, spray coating, roll coating, gravure roll coating, air doctor coating, blade coating, wire doctor coating, knife coating, reverse coating, transfer roll coating, microgravure coating, kiss coating, cast coating, slot orifice coating, calender coating, and die coating can be employed.

[0032] The coating film of the hard coat layer forming composition can be cured by irradiation with ultraviolet light using a high-pressure mercury lamp, halogen lamp, xenon lamp, fusion lamp, etc. The ultraviolet irradiation dose is 100 to 800 mJ / cm². 2 It is preferable that this be the case.

[0033] The thickness of the transparent substrate 1 and the hard coat layer 3 according to this embodiment is not particularly limited, but when used as a protective film for a decorative sheet, the thickness of the substrate is preferably 75 to 100 μm, and the thickness of the hard coat layer (film thickness after denaturation) is preferably 4 to 6 μm. However, the thickness of the transparent substrate 1 and the hard coat layer 3 can be appropriately set according to the surface hardness and overall thickness required for the hard coat film 100.

[0034] Using the hard coat film according to this embodiment, at a temperature of 62°C and an ultraviolet irradiation dose of 75 mW / cm², 2 When a lightfastness test is performed by irradiating the hard coat film with ultraviolet light for 24 hours under these conditions, the degree of yellowing ΔYI of the hard coat film before and after the weather resistance test is 0 to 0.8. Because the degree of yellowing ΔYI of the hard coat film according to this embodiment is small before and after the weather resistance test, even when used as a protective film for decorative sheets in an environment exposed to ultraviolet light, the protective film is less likely to yellow over time, and the design of the decorative sheet can be maintained.

[0035] Also, when a light resistance test is performed by irradiating ultraviolet rays for 24 hours under the conditions of a temperature of 62° C. and an ultraviolet irradiation amount of 75 mW / cm 2 using the hard coat film according to the present embodiment, it is preferable that the absolute value of the change amount of the visual transmittance Y before and after the light resistance test is 0.3 or less. When the absolute value of the change amount of the visual transmittance Y before and after the light resistance test is 0.3 or less, even when the hard coat film is used in an environment where it is exposed to ultraviolet rays as a protective film of a decorative sheet, the protective film is less likely to yellow over time, and the design property of the decorative sheet can be maintained.

[0036] Also, when a light resistance test is performed by irradiating ultraviolet rays for 24 hours under the conditions of a temperature of 62° C. and an ultraviolet irradiation amount of 75 mW / cm 2 using the hard coat film according to the present embodiment, it is preferable that the absolute value of the change amount of the chromaticity a * before and after the light resistance test is 0.2 or less. When the absolute value of the change amount of the chromaticity a * before and after the light resistance test is 0.2 or less, even when the hard coat film is used in an environment where it is exposed to ultraviolet rays as a protective film of a decorative sheet, the color tone of the protective film is less likely to change over time, and the design property of the decorative sheet can be maintained.

[0037] Also, when a light resistance test is performed by irradiating ultraviolet rays for 24 hours under the conditions of a temperature of 62° C. and an ultraviolet irradiation amount of 75 mW / cm 2 using the hard coat film according to the present embodiment, it is preferable that the absolute value of the change amount of the chromaticity b * before and after the light resistance test is 0.5 or less. When the absolute value of the change amount of the chromaticity b * before and after the light resistance test is 0.5 or less, even when the hard coat film is used in an environment where it is exposed to ultraviolet rays as a protective film of a decorative sheet, the color tone of the protective film is less likely to change over time, and the design property of the decorative sheet can be maintained.

[0038] Incidentally, the above a * and b * are La * b *These are coordinate values ​​in the color space (CIELAB).

[0039] As described above, the hard coat film 100 according to this embodiment has a hard coat layer 3 containing an ultraviolet absorber, and at a temperature of 62°C and an ultraviolet irradiation dose of 75 mW / cm², 2 Under these conditions, the degree of yellowing ΔYI before and after a 24-hour lightfastness test was 0 to 0.8, indicating minimal degradation due to UV irradiation and excellent lightfastness. [Examples]

[0040] The following describes specific examples of how the present invention is implemented.

[0041] (Preparation of hard coat film) A hard coat layer forming composition containing an ultraviolet-curable resin, a photopolymerization initiator, an ultraviolet absorber (except for Comparative Example 1), and a solvent was prepared. The ultraviolet absorbers used and the amounts added are as shown in Table 1. The amount of ultraviolet absorber added is the mass percentage shown in part of the total solid content of the hard coat layer forming composition. The maximum absorption wavelengths of the ultraviolet absorbers shown in Table 1 are as follows: A: Benzotriazole-based UV absorbers (high absorption wavelength 345nm) B: Hydroxyphenyltriazine-based UV absorber (maximum absorption wavelength 336nm) C: Hydroxyphenyltriazine-based UV absorber (maximum absorption wavelength 322nm)

[0042] [Table 1]

[0043] The prepared hard coat layer forming composition was applied to a PET film with an easy-adhesion layer and a thickness of 100 μm so that the cured film thickness would be 5 μm. After drying, the coating film was cured by irradiating it with ultraviolet light having an emission line spectrum at 365 nm using a high-pressure mercury lamp to obtain the hard coat films according to each example and comparative example.

[0044] (Test method) Using a spectrophotometer (Hitachi High-Technologies Corporation, Model: U-4100), the transmittance of the hard coat films for each example and comparative example was measured. Under the conditions of a C light source and a 2-degree field of view, the luminous transmittance Y, yellowing degree ΔYI, and chromaticity a before and after the lightfastness test were measured. * and b * The result was calculated.

[0045] Furthermore, the lightfastness test was conducted using an accelerated lightfastness tester (manufactured by Iwasaki Electric Co., Ltd., model: i Super UV Tester) on the hard coat films of each example and comparative example, at a temperature of 62°C and an irradiation dose of 75 mW / cm². 2 The device was exposed to ultraviolet light for 24 hours.

[0046] Furthermore, as an adhesion test, a cellophane tape adhesion test using a 2mm grid method was conducted. Specifically, a cross-cut was made in the hard coat layer using a utility knife to form 100 2mm square sections. Cellophane tape was then adhered to the cross-cut sections and instantly peeled off. The number of sections that remained on the transparent substrate without peeling was counted, and these remaining sections were classified into the following categories. ○: Remaining number is 95 or more △: Remaining number is 50 or more but less than 94 ×: Less than 50 remaining

[0047] (evaluation) Yellowing degree ΔYI, adhesion, luminous transmittance Y, chromaticity a * and b * The following evaluation criteria were used to assess the product.

[0048] (i) Yellowing degree ΔYI The degree of yellowness before the lightfastness test is YI0, and the degree of yellowness after the lightfastness test is YI 24 Let the degree of yellowing ΔYI be defined as ΔYI = YI 24 -YI0 was used for calculation and evaluated according to the following criteria. ○: ΔYI is between 0 and 0.8 (inclusive) Δ:ΔYI exceeds 0.8

[0049] (ii) Adhesion test The adhesion tests described above were performed before and after the lightfastness test, and the adhesion was evaluated according to the following criteria. ○: Initial adhesion before lightfastness test is ○, adhesion after lightfastness test is ○ △: Initial adhesion before lightfastness test is ○, adhesion after lightfastness test is △ ×: Either the initial adhesion before the lightfastness test or the adhesion after the lightfastness test, or both, are ×

[0050] (iii) Change in luminous transmittance Y The luminous transmittance after the lightfastness test is Y 24 The change in luminous transmittance Y, obtained by subtracting Y0 from the luminous transmittance before the lightfastness test, was evaluated according to the following criteria. ○: The absolute value of the change in luminous transmittance Y is 0.3 or less. ×: The absolute value of the change in luminous transmittance Y exceeds 0.3.

[0051] (iv) Chromaticity a * a after lightfastness test * 24 from before the lightfastness test * a minus 0 * The change in [the specified value] was evaluated according to the following criteria. ○:a * The absolute value of the change is 0.2 or less. ×:a * The absolute value of the change exceeds 0.2

[0052] (v) Chromaticity a * b after lightfastness test * 24 From before the lightfastness test * Subtracting 0 from b * The change in [the specified value] was evaluated according to the following criteria. ○:b * The absolute value of the change is 0.5 or less. ×:b * The absolute value of the change exceeds 0.5

[0053] Table 2 shows the evaluation of the hard coat film for each example and comparative example.* The change in amount and b * If all evaluation items for the change in the value were marked with a circle (○), it was marked with a cross (×). If one or more evaluation items were marked with a cross (×), it was marked with a triangle (△).

[0054] [Table 2]

[0055] As shown in Table 2, the hard coat films according to Examples 1-1 to 1-5 contain a hydroxyphenyltriazine-based UV absorber in the hard coat layer, and the degree of yellowing ΔYI before and after the lightfastness test was 0 or more and 0.3 or less, confirming that yellowing due to UV irradiation is suppressed. Furthermore, the hard coat films according to Examples 1-1 to 1-5 showed a change in luminous transmittance Y, a * The change in amount and b * The amount of change was suppressed, and the adhesion between the hard coat layer and the transparent substrate was also good, confirming its suitability as a protective film for decorative sheets.

[0056] The hard coat film in Comparative Example 1 did not have sufficient UV absorption because the hard coat layer did not contain an UV absorber. As a result, the degree of yellowing ΔYI before and after the lightfastness test was large, and the degradation of the PET film was not adequately suppressed. Furthermore, in Comparative Example 1, the adhesion decreased after the lightfastness test, and the luminous transmittance Y and chromaticity a before and after the lightfastness test were also poor. * and b * Because the amount of change could not be sufficiently suppressed, it was not suitable as a protective film for decorative sheets.

[0057] The hard coat films in Comparative Examples 2-1 to 2-4 contained a benzotriazole-based UV absorber in the hard coat layer, but sufficient UV absorption was not achieved, resulting in a large degree of yellowing ΔYI before and after the lightfastness test, and insufficient suppression of PET film degradation. Furthermore, similar to Comparative Example 1, a decrease in adhesion occurred after the lightfastness test, and the luminous transmittance Y and chromaticity a before and after the lightfastness test were observed. * and b *Because the amount of change could not be sufficiently suppressed, it was not suitable as a protective film for decorative sheets.

[0058] The hard coat films in Comparative Examples 3-1 to 3-8 contained a hydroxyphenyltriazine-based UV absorber in the hard coat layer, but they were unable to sufficiently suppress the degree of yellowing ΔYI before and after the lightfastness test, resulting in insufficient suppression of PET film degradation. Furthermore, similar to Comparative Example 1, the luminous transmittance Y and chromaticity a before and after the lightfastness test were also insufficient. * and b * Because the amount of change could not be sufficiently suppressed, it was not suitable as a protective film for decorative sheets. In Comparative Examples 3-1 to 3-5, similar to Comparative Example 1, a decrease in adhesion occurred after the lightfastness test. In Comparative Examples 3-6 to 3-8, the amount of UV absorber was too high, which inhibited the curing of the hard coat layer forming composition, resulting in poor adhesion before the lightfastness test. It should be noted that the adhesion evaluation after the lightfastness test in Comparative Examples 3-6 and 3-7 was positive because curing was accelerated by UV irradiation during the lightfastness test.

[0059] The hard coat films of Comparative Examples 4-1 to 4-4 were prepared by adding the same UV absorber as in Examples 1-1 to 1-5 to the hard coat layer. In the hard coat films of Comparative Examples 4-1 and 4-2, the amount of UV absorber was too low, resulting in insufficient UV absorption and failure to adequately suppress the degree of yellowing ΔYI before and after the lightfastness test. Also, similar to Comparative Example 1, the chromaticity a before and after the lightfastness test * and b * Because the amount of change could not be sufficiently suppressed, it was not suitable as a protective film for decorative sheets. In the hard coat films of Comparative Examples 4-3 and 4-4, the amount of ultraviolet absorber was too high, which inhibited the curing of the hard coat layer forming composition, resulting in reduced adhesion before the lightfastness test. Furthermore, in Comparative Examples 4-3 and 4-4, the degree of yellowing ΔYI before and after the lightfastness test could not be sufficiently suppressed compared to the examples. [Industrial applicability]

[0060] The present invention can be used as a hard coat film, and in particular as a protective film for articles used in environments exposed to ultraviolet light, such as decorative sheets. [Explanation of Symbols]

[0061] 1 Transparent base material 2 Easy adhesive layer 3. Hard court layer 100 Hard Coat Film 200 decorative sheets

Claims

1. A substrate made of polyethylene terephthalate, The substrate comprises a hard coat layer laminated on the outermost layer on one side of the substrate, The hard coat layer and the substrate are further provided with an easy-adhesion layer, The hard coat layer is a cured product of a composition containing an ultraviolet-curable resin, a photopolymerization initiator, and an ultraviolet absorber (however, it does not contain a hindered amine compound). The ultraviolet absorber consists of a hydroxyphenyltriazine compound having a maximum absorption wavelength of 280 to 330 nm, and its content is in proportion to 3 to 7% by mass of the hard coat layer. The thickness of the hard coat layer is 4 to 6 μm. Using an accelerated lightfastness tester (manufactured by Iwasaki Electric Co., Ltd., model: i-Super UV Tester), the test was conducted at a temperature of 62°C and an ultraviolet irradiation dose of 75 mW / cm². ２ The absolute value of the change in luminous transmittance Y before and after a 24-hour lightfastness test irradiated under the specified conditions is 0.30 or less, and the hue a ＊ The absolute value of the change in hue b is 0.20 or less. ＊ The absolute value of the change is 0.48 or less. A hard coat film in which, after the lightfastness test, the hard coat layer is subjected to a cellophane tape adhesion test using a 2 mm grid method, forming 100 2 mm square sections, to which cellophane tape is adhered, and then the cellophane tape is peeled off, leaving 50 or more sections on the substrate without peeling.

2. The hard coat film according to claim 1, wherein the degree of yellowing ΔYI before and after the lightfastness test is 0 to 0.

7.

3. The hard coat film according to claim 1 or 2, wherein the thickness of the substrate is 75 to 100 μm.

4. The hard coat film according to any one of claims 1 to 3, wherein the photopolymerization initiator has an absorption wavelength range of 200 to 380 nm.

5. A decorative sheet comprising a hard coat film according to any one of claims 1 to 4.

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