Decorative sheet and production method thereof

Abstract

A decorative sheet according to one embodiment of the present invention comprises: a base layer; a transparent layer provided on the base layer; and an ultraviolet cured coating layer provided on the transparent layer, wherein the ultraviolet cured coating layer comprises acrylic resin and an ultraviolet absorbent, and the rate of change of ultraviolet absorbent content in the ultraviolet cured coating layer is 10% or less under accelerated assessment using method 1.

Description

Decorative sheet and method of manufacturing the same

[0001] The present application claims the benefit of the filing dates of Korean patent applications No. 10-2024-0162888, No. 10-2024-0162879 and No. 10-2024-0162893 filed with the Korean Intellectual Property Office on November 15, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a decorative sheet and a method for manufacturing the same.

[0003] Films intended for decoration are coated or bonded for interior and exterior use on materials in various fields, such as automobiles, construction materials, advertising materials, flooring, and wallpaper. In the case of coating materials, a coating composition is applied directly to the target and then cured; while this offers the advantage of having no restrictions on the shape of the target, it has limitations in color realization and is susceptible to changes over time. On the other hand, decorative films are primarily based on polyvinyl chloride (PVC) resin, which offers the advantages of low cost, excellent transparency, and colorability. Furthermore, as a thermoplastic material, PVC resin softens and exhibits fluidity under external conditions, then hardens into a solid upon cooling; it also softens and regains fluidity when external conditions are applied, resulting in excellent moldability. Therefore, decorative films possessing these characteristics offer the advantage of enabling a wide variety of colors and designs.

[0004] However, these deco films have limitations depending on the shape of the application target due to the characteristics of the film, and in particular, existing exterior deco films contain metal ions (more precisely, free ion impurities such as Fe) within the black color pigment, so they exhibit weather resistance problems such as localized yellowing (brown spots) caused by prolonged UV irradiation.

[0005] Therefore, in this technical field, there is a demand for the development of weather-resistant deco films, decorative sheets, etc. that can be applied as building exterior materials, as they can suppress yellowing even during prolonged UV irradiation.

[0006] The present invention aims to provide a decorative sheet and a method for manufacturing the same. More specifically, the present invention aims to provide a decorative sheet having excellent weather resistance and capable of controlling surface gloss characteristics, and a method for manufacturing the same.

[0007] One embodiment of the present invention is,

[0008] It comprises a base layer; a transparent layer provided on the base layer; and a UV-curing coating layer provided on the transparent layer,

[0009] The above UV-curing coating layer comprises an acrylic resin and a UV absorber, and

[0010] A decorative sheet is provided in which, when evaluated according to the following method 1, the rate of change in the content of the UV absorber included in the UV-cured coating layer is 10% or less.

[0011] [Method 1]

[0012] The above decorative sheet is subjected to accelerated heat treatment by being left in a 60℃ oven for 30 days, and

[0013] For the UV-cured coating layer before and after accelerated degradation treatment, the peak area per weight (area / mg) of the UV absorber was calculated from the graph analyzed by pyrolysis gas chromatography mass spectrometry (Pyro-GCMS), and the rate of change in the content of the UV absorber was calculated according to the following mathematical formula 1.

[0014] [Mathematical Formula 1]

[0015] Rate of change in UV absorber content (%) = [(Peak area per weight of UV absorber before accelerated degradation treatment - Peak area per weight of UV absorber after accelerated degradation treatment) / (Peak area per weight of UV absorber before accelerated degradation treatment)] × 100

[0016] In addition, another embodiment of the present invention is,

[0017] Step of preparing the base layer;

[0018] A step of forming a transparent layer on the above base layer; and

[0019] A step of forming a UV-cured coating layer by applying a coating layer composition comprising an acrylic resin, a triazole-based UV absorber, and a hindered amine-based light stabilizer onto the above transparent layer, and then performing a UV curing process.

[0020] A method for manufacturing a decorative sheet including is provided.

[0021] According to the present invention, by including a UV-curing coating layer in the decorative sheet, the yellowing phenomenon of the decorative sheet can be suppressed even during prolonged UV irradiation, thereby providing a decorative sheet with excellent weather resistance that can be applied as an exterior building material.

[0022] In addition, the decorative sheet according to the present invention can have its surface gloss varied, such as glossy or matte, depending on the manufacturing process of the UV-cured coating layer, so it can be applied to various products.

[0023] FIG. 1 is a schematic diagram showing a decorative sheet according to one embodiment of the present invention.

[0024] FIG. 2 is a schematic diagram showing a decorative sheet according to one embodiment of the present invention.

[0025] Figure 3 is a figure showing mapping analysis images of the decorative sheet of Experimental Example 1 before and after accelerated deterioration treatment.

[0026] Figure 4 is a figure showing mapping analysis images of the decorative sheet of Experimental Example 5 before and after accelerated deterioration treatment.

[0027] Figure 5 is a figure showing analysis images according to pyrolysis gas chromatography mass spectrometry before and after accelerated deterioration treatment of the decorative sheet of Experimental Example 1.

[0028] [Explanation of the symbol]

[0029] 10: Base layer

[0030] 20: Transparent layer

[0031] 30: UV-cured coating layer

[0032] 40: Print layer

[0033] The present invention will be described in more detail below.

[0034] In the present invention, when it is said that a certain member is located "on" another member, this includes not only the case where a certain member is in contact with another member, but also the case where another member exists between the two members.

[0035] In the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0036] Generally, a decorative sheet consists of a base layer, a printed layer, and a transparent layer laminated sequentially. Among these, the base layer mainly contains polyvinyl chloride (PVC) resin and a plasticizer, the printed layer contains pigments and binder resins, and the transparent layer mainly contains acrylate-based resin, an ultraviolet absorber, and an impact reinforcing agent. However, as mentioned above, if ultraviolet rays are continuously irradiated onto a base layer containing metal ions, localized yellowing of the base layer inevitably occurs due to the catalytic reaction of the metal ions.

[0037] Accordingly, methods such as formulations that simply suppress the yellowing of the base layer have been proposed; however, even in this case, there were limitations in improving the yellowing phenomenon caused by metal ions originating from the interface between the base layer and the printing layer, which is the upper surface of the base layer. Therefore, to prevent or minimize yellowing, a measure is required to prevent ultraviolet rays from reaching the base layer.

[0038] Furthermore, conventional decorative sheets for building exteriors harbor the following additional problems in addition to the aforementioned issues. Generally, the base layer of a decorative sheet for building exteriors contains a plasticizer. This plasticizer affects the transparent layer, causing UV absorbers scattered within the transparent layer to diffuse and migrate through the printed layer to the base layer, thereby reducing the UV blocking ability of the decorative sheet. Additionally, after the decorative sheet for building exteriors is exposed to UV rays for a long period, the UV absorbers contained in the transparent layer are lost, which may result in UV rays being directly irradiated onto the base layer.

[0039] Furthermore, even if the base layer of the decorative sheet for building exteriors does not contain plasticizers, a problem arises in which some of the UV absorbers contained in the transparent layer are lost after prolonged exposure to ultraviolet rays. In other words, when the decorative sheet for building exteriors is exposed to ultraviolet rays for an extended period, some of the UV absorbers evenly distributed within the transparent layer are lost; consequently, this leads to the problem of UV rays passing through the transparent layer and the printed layer to directly irradiate the base layer.

[0040] Therefore, the present invention aims to develop a decorative sheet with excellent weather resistance that can be applied as an exterior building material, capable of solving the aforementioned problems and suppressing yellowing even under prolonged UV irradiation.

[0041] A decorative sheet according to one embodiment of the present invention comprises a base layer; a transparent layer provided on the base layer; and a UV-curing coating layer provided on the transparent layer, wherein the UV-curing coating layer comprises an acrylic resin and a UV absorber, and when subjected to accelerated evaluation according to Method 1 below, the rate of change in the content of the UV absorber included in the UV-curing coating layer is 10% or less.

[0042] [Method 1]

[0043] The above decorative sheet is subjected to accelerated heat treatment by being left in a 60℃ oven for 30 days, and

[0044] For the UV-cured coating layer before and after accelerated degradation treatment, the peak area per weight (area / mg) of the UV absorber was calculated from the graph analyzed by pyrolysis gas chromatography mass spectrometry (Pyro-GCMS), and the rate of change in the content of the UV absorber was calculated according to the following mathematical formula 1.

[0045] [Mathematical Formula 1]

[0046] Rate of change in UV absorber content (%) = [(Peak area per weight of UV absorber before accelerated degradation treatment - Peak area per weight of UV absorber after accelerated degradation treatment) / (Peak area per weight of UV absorber before accelerated degradation treatment)] × 100

[0047] A decorative sheet according to one embodiment of the present invention comprises: a base layer; a transparent layer provided on the base layer; and a UV-curing coating layer provided on the transparent layer.

[0048] The base layer is intended not only to improve weather resistance but also to support a printed layer, a transparent layer, and a UV-cured coating layer that may be provided on the base layer, and may be formed in the shape of a sheet or a film. The base layer may include one or more selected from the group consisting of polyvinyl chloride resin (PVC), acrylic resin, thermoplastic polyolefin resin (TPO), acrylonitrile butadiene styrene (ABS) copolymer, and acrylonitrile styrene acrylate (ASA), and among these, it is more preferable to include polyvinyl chloride resin (PVC).

[0049] The thickness of the base layer may be 100㎛ to 400㎛, and by having a thickness within the above range, the transparent layer and the UV-cured coating layer can be sufficiently supported without excessively increasing the total thickness of the decorative sheet according to the present invention.

[0050] In addition, the above base layer may further be provided with an adhesive layer on the opposite side of the side where the transparent layer is provided (i.e., the side that comes into contact with the target substrate to which the decorative sheet is to be attached). By attaching the decorative sheet to the target article to which it is to be attached through the adhesive layer, the decorative sheet can coat the target article as a surface finishing material of the target article. The adhesive layer may include one or more selected from the group consisting of hydroxyl group-containing acrylic adhesives, saturated polyester adhesives, urethane adhesives, and combinations thereof. In addition, the adhesive layer may include an isocyanate-based curing agent exemplified by xylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), etc., and may include conventional solvents such as methyl ethyl ketone, toluene, ethyl acetate, and methyl isobutyl ketone as a solvent.

[0051] The adhesive layer can be formed by applying a comma coat to a thickness of 10㎛ to 15㎛ using an adhesive such as polyester, and by forming it as an opaque layer, a more beautiful and vivid three-dimensional effect can be produced. In addition, when forming the adhesive layer as an opaque layer, various colored pigments may be added to the adhesive. Furthermore, a release film may be attached to the opposite side of the adhesive layer that does not face the base layer, and in this case, the decorative sheet can be attached to the substrate surface after the release film is removed, and can be applied as a finishing material, for example, for the exterior of a building or exterior materials.

[0052] In addition, the base layer may further include a plasticizer for the purpose of imparting or increasing plasticity to the decorative sheet. Since adding a plasticizer to the base layer of a conventional decorative sheet is a common technique, a detailed explanation thereof will be omitted.

[0053] The above transparent layer is used to protect the base layer from external environmental factors such as ultraviolet rays, and any commercially available film for high weather resistance applications may be applied. For example, the above transparent layer may include one or more of polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF). The above transparent layer may be a single-layer structure including polymethyl methacrylate (PMMA), a single-layer structure including polyvinylidene fluoride (PVDF), a single-layer structure including polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF), or a multi-layer structure including a combination thereof, but is not limited thereto.

[0054] The above transparent layer may further include one or more of a UV absorber and a light stabilizer. The UV absorber that may be included in the above transparent layer may be any component commonly used as a UV absorber in the art and is not particularly limited. For example, the UV absorber included in the above transparent layer may include one or more products such as Tinuvin 329, Tinuvin 234, Tinuvin P, Tinuvin 1577, etc., but is not limited thereto. In addition, the light stabilizer that may be included in the above transparent layer may be any component commonly used as a light stabilizer in the art and is not particularly limited. For example, the light stabilizer included in the transparent layer may include one or more of 2-hydroxybenzophenone, 2-hydroxyphenylbenzotriazole, hydroxyphenyltriazine, hindered amine, organic nickel compound, salicylate, resorcinol monobenzoate, cinnamate derivative, oxanilide, para-hydroxybenzoate, etc., but is not limited thereto. The ultraviolet absorber and light stabilizer included in the transparent layer may be the same as or different from the ultraviolet absorber and light stabilizer included in the ultraviolet curing coating layer described later.

[0055] In addition, the transparent layer may further include one or more types of impact reinforcing agents, antioxidants, etc. The impact reinforcing agents and antioxidants may be those known in the art and are not particularly limited.

[0056] In one embodiment of the present invention, a printed layer may be further included between the base layer and the transparent layer.

[0057] The printing layer may include a binder resin comprising an acrylic resin or a vinyl resin, and a urethane-based ink (pigment), and may be formed by applying a pattern to the upper surface of the base layer using various printing methods such as transfer printing, gravure printing, screen printing, offset printing, rotary printing, and flexographic printing. The thickness of the printing layer may be 1 μm to 20 μm, and by having a thickness within the above range, sufficient patterns or colors can be realized without excessively increasing the total thickness of the decorative sheet.

[0058] In one embodiment of the present invention, the UV-curing coating layer comprises an acrylic resin and a UV absorber.

[0059] In one embodiment of the present invention, the UV-curing coating layer may further include a light stabilizer. In this case, it is preferable that the UV absorber included in the UV-curing coating layer is a triazole-based UV absorber and the light stabilizer is a hindered amine-based light stabilizer.

[0060] The above UV-curable coating layer can be manufactured by a method of forming a coating layer by applying and curing a coating layer composition onto the transparent layer. Accordingly, the UV-curable coating layer can be provided in direct contact with the transparent layer without a separate adhesive layer.

[0061] A decorative sheet according to one embodiment of the present invention includes a UV-curing coating layer on the transparent layer, thereby suppressing the yellowing phenomenon of the decorative sheet even during prolonged UV irradiation, and thus can provide a decorative sheet with excellent weather resistance that can be applied as an exterior building material.

[0062] The above triazole-based ultraviolet absorber may use a benzotriazole compound. The above benzotriazole compounds include 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-amyl-5'-isobutylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-isobutyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-isobutyl-5'-propylphenyl)-5-chlorobenzotriazole, and 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole. Examples include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2'-hydroxy-5'-(1,1,3,3-tetramethyl)phenyl]benzotriazole, 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy, 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol, etc. Commercially available products include TINUVIN PS, TINUVIN 99-2, TINUVIN 109, TINUVIN 328, TINUVIN 384-2, TINUVIN 900, TINUVIN 928, TINUVIN 171, TINUVIN 1130 (all manufactured by BASF), UV 384-2 (manufactured by Baoxu Chemical), etc.

[0063] The above hindered amine-based light stabilizer may be a hindered amine-based compound having a 2,2,6,6-tetramethyl-piperidine ring, and may also be a compound having multiple 2,2,6,6-tetramethyl-piperidine rings in one molecule. Examples of commercially available products include TINUVIN 770DF, TINUVIN 152, and TINUVIN 123 from BASF, ADK STAB LA-72 and ADK STAB LA-81 from ADEKA, and UV 292 from Baoxu Chemical.

[0064] In one embodiment of the present invention, the triazole-based UV absorber included in the UV-curing coating layer absorbs ultraviolet rays and converts them into thermal energy, thereby blocking the ultraviolet rays from reaching the interior of the material and preventing color change of the decorative sheet. In particular, the triazole-based UV absorber can exhibit the effect of suppressing the yellowing (brown spot) phenomenon caused by Fe ions included in the base layer.

[0065] In one embodiment of the present invention, the hindered amine-based light stabilizer included in the UV-cured coating layer can suppress or stop free radical reactions caused by ultraviolet rays absorbed inside the material, thereby preventing deterioration such as color change or yellowing of the decorative sheet.

[0066] In particular, according to one embodiment of the present invention, the UV-curing coating layer simultaneously comprises a triazole-based UV absorber and a hindered amine-based light stabilizer. Since the triazole-based UV absorber blocks UV rays exposed to the decorative sheet and the hindered amine-based light stabilizer suppresses deterioration that may occur if UV rays are absorbed, the protective effect against UV rays can be maximized. If the UV-curing coating layer comprises only a triazole-based UV absorber, it is difficult to prevent internal decomposition or deterioration when the decorative sheet is exposed to an outdoor environment for a long time. Furthermore, if the UV-curing coating layer comprises only a hindered amine-based light stabilizer, UV blocking is insufficient, making it prone to damage to the surface of the decorative sheet.

[0067] In one embodiment of the present invention, the content of the triazole-based UV absorber and the hindered amine-based light stabilizer included in the UV-curing coating layer may vary depending on the type of product and the usage environment. In the present invention, since the UV-curing coating layer is formed as a thin, transparent layer on the surface of a decorative sheet, it is preferable that the content of the triazole-based UV absorber be higher than the content of the hindered amine-based light stabilizer. More specifically, based on the total weight of the acrylic resin, the content of the triazole-based UV absorber may be 0.5% to 5% by weight and 1% to 3% by weight, but is not limited thereto. Additionally, based on the total weight of the acrylic resin, the content of the hindered amine-based light stabilizer may be 0.1% to 4% by weight and 0.5% to 2% by weight, but is not limited thereto.

[0068] If the content of the triazole-based UV absorber and hindered amine-based light stabilizer exceeds the aforementioned range, the UV absorber and light stabilizer may excessively absorb UV rays during the UV curing reaction stage of the UV-cured coating layer. Consequently, there may not be enough UV rays for the photoinitiator to start the polymerization reaction, which could result in the coating layer not being fully cured. Furthermore, physical properties such as hardness, adhesion, and chemical resistance of the UV-cured coating layer may be significantly degraded, and migration phenomena may occur in which the UV absorber and / or light stabilizer flow out of the surface of the coating layer, which is undesirable.

[0069] In one embodiment of the present invention, the surface of the ultraviolet curing coating layer has a structure in which wrinkles are formed, and the roughness (Rz) of the surface of the ultraviolet curing coating layer may be 1 μm to 10 μm and 2 μm to 9 μm.

[0070] The above-mentioned wrinkled structure means that the UV-cured coating layer includes wrinkles on at least one surface, and the UV-cured coating layer has three-dimensional surface irregularities due to the wrinkles. For example, the surface has irregularities including large and small ridges, valleys, and wrinkles formed from them that can be seen as a predetermined shape. Each of the ridges, valleys, and wrinkles may have a regular or irregular shape. Such a wrinkled surface may also be referred to as a surface having a microfolding structure.

[0071] When observing the surface of the UV-cured coating layer in which wrinkles are formed in the normal direction of the UV-cured coating layer, ridges, valleys, wrinkles, and irregularities formed therefrom can be observed over the entire area of ​​the surface, for example, while undergoing the curing process described later.

[0072] The above wrinkles can be observed in a form including a directional line shape (e.g., straight line, curve). As one example, surface wrinkles formed by the repetition of straight and curved shapes can impart curvature, such as a mountain range shape, to the surface of the UV-cured coating layer. The surface irregularity structure formed by wrinkles having a line shape as described above is clearly distinct from the so-called point-wise irregularity shape formed by using particles in the composition for forming the UV-cured coating layer or by using emulsion dispersion.

[0073] Additionally, the surface of the UV-cured coating layer may include wrinkles that can be seen with a predetermined size and shape. For example, the wrinkles may have a width at the nm level (less than about 1 μm) and have a line (straight or curved) shape extending several micrometers (μm) or more. The width and / or height of the wrinkles and the length of the wrinkles can be confirmed from an image of the surface on which the wrinkles are formed. The image can be obtained from an optical microscope, a scanning electron microscope (SEM), a confocal laser scanning microscope (CLSM), etc. Furthermore, the length in the direction of extension may be greater than the width. Specifically, the ends of wrinkles extended in a straight or curved shape may be incorporated into the UV-cured coating layer with a slope in which the height gradually decreases. In some cases, the end of a wrinkle having the above size and shape may become the starting point of another wrinkle or a connection point with another wrinkle. In addition, when observing the cross-sectional curve near the wrinkle in a direction perpendicular to the extension direction of the wrinkle, the width of the wrinkle may be incorporated into the resin layer with a slope in which the height gradually decreases in both directions starting from the point or part (e.g., ridge) that forms the height of the wrinkle. Meanwhile, when a ridge and an adjacent valley form the wrinkle or a part thereof, the visible area of ​​the shape including the valley can be considered as the width of the wrinkle.

[0074] The above UV-curing coating layer may have a thickness within an appropriate range that does not affect the durability of the decorative sheet. For example, the thickness of the above UV-curing coating layer may be 3㎛ or more, 5㎛ or more, 10㎛ or more, or 15㎛ or more. Additionally, for example, the thickness of the above UV-curing coating layer may be 100㎛ or less, 90㎛ or less, 80㎛ or less, 70㎛ or less, 60㎛ or less, 50㎛ or less, 40㎛ or less, 30㎛ or less, 20㎛ or less, or 15㎛ or less. The thickness of the UV-curing coating layer mentioned in the present invention may refer to the average thickness of the UV-curing coating layer excluding the height of dense wrinkles, and in some cases, may refer to a thickness including the average thickness of the UV-curing coating layer excluding the height of dense wrinkles and half the value of the average maximum height of dense wrinkles.

[0075] The above UV-curing coating layer may additionally comprise 10 weight percent or less of organic particles and / or inorganic particles based on the total weight of the acrylic resin. The type of particles is not particularly limited, and known organic or inorganic particles may be used. In one example, the inorganic particles may be particles that function as so-called matting agents. In one example, the inorganic particles may be particles having a size in the range of 3 µm to 10 µm. Here, particle size may refer to the average size of the particles and may be a d50 value. When particles of the above range are used, they may help to secure the surface roughness described above. As an example, silica particles may be used. Additionally, the organic particles may also be particles having a size in the range of 5 µm to 10 µm. As an example, polyurethane particles may be used.

[0076] In one embodiment of the present invention, the surface gloss of the decorative sheet can be varied to a glossy, matte, etc., depending on the manufacturing process of the UV-cured coating layer. The gloss level of the surface of the UV-cured coating layer under a gloss level of 60° may be 10 or less, and may be 5 or less. Additionally, the gloss level of the surface of the UV-cured coating layer under a gloss level of 60° may be 20 or more, and may be 30 or more. Additionally, the gloss level of the surface of the UV-cured coating layer under a gloss level of 60° may be greater than 10 and less than 20.

[0077] In one embodiment of the present invention, during accelerated evaluation according to Method 1, the rate of change in the content of the UV absorber included in the UV-cured coating layer may be 10% or less, 5% or less, 3% or less, or 1% or less. During accelerated evaluation according to Method 1, if the rate of change in the content of the UV absorber included in the UV-cured coating layer exceeds 10%, it is undesirable because yellowing may occur due to prolonged UV irradiation.

[0078] In one embodiment of the present invention, when evaluating weather resistance according to Method 2 below, the color difference (△E) of the UV-cured coating layer after 500 hours may be 3.5 or less, 3.3 or less, 3.0 or less, or 2.7 or less. When evaluating weather resistance according to Method 2 below, if the color difference (△E) of the UV-cured coating layer after 500 hours exceeds 3.5, it is not desirable because it may be evaluated that yellowing occurs due to prolonged UV irradiation.

[0079] [Method 2]

[0080] A metal-halide lamp equipped with a UVCF10 filter was irradiated with ultraviolet and visible light in the range of 295 nm to 800 nm onto the decorative sheet, and the hourly irradiation dose of ultraviolet and visible light was 5.4 mJ / cm² 2 The temperature of the Black Standard was set to 63℃ and the relative humidity to 63%, and

[0081] After measuring the colors (L*, a*, b*) around 500 hours using a colorimeter, the color difference (△E) of the surface of the decorative sheet was calculated according to the following mathematical formula 2.

[0082] [Mathematical Formula 2]

[0083] △E = [(△L*) 2 + (△a*) 2 + (△b*) 2 ] 1 / 2

[0084] In addition, in one embodiment of the present invention, when evaluating weather resistance according to method 2, the color difference (△E) of the UV-cured coating layer after 400 hours, rather than 500 hours, may be 2.9 or less, 2.7 or less, 2.5 or less, and 2.3 or less.

[0085] In addition, in one embodiment of the present invention, when evaluating weather resistance according to method 2, the color difference (△E) of the UV-cured coating layer after 300 hours, rather than 500 hours, may be 2.3 or less, 2.2 or less, 2.15 or less, and 2.1 or less.

[0086] In addition, in one embodiment of the present invention, when evaluating weather resistance according to method 2, the color difference (△E) of the UV-cured coating layer after 100 hours, rather than 500 hours, may be 1.0 or less, 0.95 or less, 0.9 or less, and 0.88 or less.

[0087] According to the present invention, by including a UV-curing coating layer in a decorative sheet, the yellowing phenomenon of the decorative sheet can be suppressed even during prolonged UV irradiation, thereby satisfying the color difference value of the aforementioned UV-curing coating layer.

[0088] A decorative sheet according to one embodiment of the present invention is schematically illustrated in FIGS. 1 and FIG. 2 below. As shown in FIG. 1 below, the decorative sheet according to one embodiment of the present invention comprises a base layer (10); a transparent layer (20) provided on the base layer (10); and a UV-curing coating layer (30) provided on the transparent layer (20). At this time, the UV-curing coating layer (30) may include an acrylic resin, a triazole-based UV absorber, and a hindered amine-based light stabilizer. Additionally, as shown in FIG. 2 below, a printed layer (40) may be further included between the base layer (10) and the transparent layer (20).

[0089] A method for manufacturing a decorative sheet according to one embodiment of the present invention comprises the steps of: preparing a base layer; forming a transparent layer on the base layer; and applying a composition for a coating layer comprising an acrylic resin, a triazole-based ultraviolet absorber, and a hindered amine-based light stabilizer onto the transparent layer, and then performing an ultraviolet curing process to form an ultraviolet cured coating layer.

[0090] In one embodiment of the present invention, the step of forming a printed layer between the base layer and the transparent layer may be further included.

[0091] In the method for manufacturing a decorative sheet according to one embodiment of the present invention, the details regarding the base layer, printing layer, transparent layer, and UV-curing coating layer are the same as those described above, so a detailed description thereof will be omitted.

[0092] The acrylic resin of the above coating layer composition may include monomers and oligomers containing acrylate-based functional groups.

[0093] The above coating layer composition may include one or more selected from 1 to 50 parts by weight of a monofunctional first monomer, 1 to 40 parts by weight of a difunctional second monomer, and 1 to 10 parts by weight of a polyfunctional third monomer, based on 100 parts by weight of the sum of the monomer and the oligomer.

[0094] The above coating layer composition may include one or more selected from 1 to 60 parts by weight of a difunctional first oligomer, 1 to 60 parts by weight of a trifunctional second oligomer, and 1 to 10 parts by weight of a hexafunctional or ninth functional third oligomer, based on 100 parts by weight of the sum of the monomer and the oligomer.

[0095] The above coating layer composition may additionally include 1 to 10 parts by weight of an initiator based on 100 parts by weight of the sum of the monomer and the oligomer.

[0096] 상기 모노머는 Caprolactone acrylate(CA), Cyclic trimethylolpropane formal acrylate(CTFA), 3,3,5-Trimethyl cyclohexyl acrylate(TMCHA), Isobornyl acrylate(IOBA), 4-Tert-butylcyclohexyl acrylate(TBCHA), Benzyl acrylate(BZA), Lauryl acrylate(KA-C12,13), Tridecyl acrylate(TDA), Isodecyl acrylate(IDA), Phenol (EO) acrylate(PHEA), Phenol (EO)2acrylate(PHEA-2), Phenol (EO)4acrylate(PHEA-4), Tetrahydrofurfuryl acrylate(THFA), Nonyl phenol (EO)4acrylate(NP(EO)4A), Nonyl phenol (EO)8acrylate(NP(EO)8A), Nonyl phenol (PO)2acrylate(NP(PO)2A), Ethoxy ethoxy ethyl acrylate(EOEOEA), Stearyl acrylate(SA), 2-Hydropropylacrylate(HPA), 1,6-Hexanediol diacrylate(HDDA), 1,6-Hexanediol (EO) n diacrylate(HD(EO) nDA), Hydroxy pivalic acid neopentyl glycol diacrylate(HPNDA), Neopentylglycol (PO)2diacrylate(NPG(PO)2DA), Tripropylene glycol diacrylate(TPGDA), Dipropylene glycol diacrylate(DPGDA), Triethylene glycol diacrylate(TEGDA), Tricyclodecane dimethanol diacrylate(TCDDA), Tetrathylene glycol diacrylate(TTEGDA), Polyethylene glycol (200~600) diacrylate(PEG(200~600)DA), Polypropylene glycol 400 diacrylate(PPG400DA), Trimethylolpropane triacrylate(TMPTA), Trimethylolpropane (EO) n tricarylate(TMP(EO) n (n=3~15)TA), Glycerine (PO)3triacrylate(GPTA), Pentaerythritol triacrylate(PETIA), Trimethylolpropane (PO)3triacrylate(TMP(PO)3TA), Tris(2-hydroxyethyl)isocyanurate triacrylate(THEICTA), Pentaerythritol (EO) n tetraacrylate(PE(EO) nTTA), Ditrimethylolpropane tetraacrylate(DTMPTTA), Pentaerythritol tetraacrylate(PETTA), Dipentaerythritol pentaacrylate(DPPA), Dipentaerythritol Hexaacrylate(DPHA), N,N-Dimethyl acrylamide(DMAA), Polypropylene glycol monomethacrylate(PPG5MMA), Benzyl methacrylate(BZMA), Isodecyl methacrylate(IDMA), Phenoxyethyl methacrylate(PHEMA), Tetrahydrofurfuryl methacrylate(THFMA), Stearyl methacrylate(SMA), 1,6-Hexanediol dimethacrylate(HDDMA), 1,4-Butanediol dimethacrylate(BDDMA), Neopentyl glycol dimethacrylate(NPGDMA), Ethylene glycol dimethacrylate(EGDMA), Diethylene glycol dimethacrylate(DEGDMA), Triethylene glycol dimethacrylate(TEGDMA), 1,3-Butylene glycol dimethacrylate(BGDMA), Polyethylene glycol 200~600 dimethacrylate(PEG200~400DMA), Trimethylolpropane trimethacrylate(TMPTMA) 등에서 선택되는 1종 이상일 수 있다.

[0097] The above oligomer may be one or more selected from epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, organotin-free urethane acrylate, polyester acrylate, water-borne acrylate, water-soluble acrylate, silicon acrylate, melamine acrylate, acrylic acrylate, caprolactone acrylate, oligo amine acrylate, etc.

[0098] The above initiator is an initiator capable of forming a film upon curing of the composition, and materials known in the art may be used.

[0099] The method of applying a coating layer composition onto the above-mentioned transparent layer can be carried out by methods known in the art, for example, using a Mayer, D-bar, rubber roll, G / V roll, air knife, slot die, microgravure, etc.

[0100] In one embodiment of the present invention, the ultraviolet curing process may include a step of curing the composition for the coating layer by irradiating it with short-wavelength light in one step, or curing it by irradiating it in two or three steps under different conditions.

[0101] In the above UV curing process, if the composition for the coating layer is cured by irradiating it with short wavelength light of a specific range in one step, the gloss level of the surface of the UV-cured coating layer with a gloss of 60° may exhibit glossy characteristics. Additionally, if the composition for the coating layer is cured by irradiating it with short wavelength light of a specific range in two or three steps under different conditions, the gloss level of the surface of the UV-cured coating layer with a gloss of 60° may exhibit matte characteristics.

[0102] In one embodiment of the present invention, the step of curing the composition for a coating layer by irradiating light in the first step may include a light irradiation step of forming an ultraviolet cured coating layer by irradiating light with a wavelength of 200 nm to 450 nm onto the applied composition for a coating layer. The light irradiation step may be performed in an air atmosphere using light with a wavelength of 200 nm to 450 nm, specifically 200 nm to 400 nm, 250 nm to 380 nm, 280 nm to 380 nm, 250 nm to 350 nm, or 280 nm to 320 nm. When performing the light irradiation step, the distance between the composition and the light source, that is, the distance from the surface of the applied composition to the light source, may be 50 mm or less, 40 mm or less, 30 mm or less, or 20 mm or less. Specifically, the upper limit of the distance may be 19mm or less, 18mm or less, 17mm or less, 16mm or less, 15mm or less, 14mm or less, 13mm or less, 12mm or less, 11mm or less, or 10mm or less, and the lower limit may be 0.5mm or more, 1mm or more, 2mm or more, 3mm or more, 4mm or more, or 5mm or more. The amount of light irradiated in the above light irradiation step may be 150 mJ / ㎠ or more, specifically 160 mJ / ㎠ or more, 170 mJ / ㎠ or more, 180 mJ / ㎠ or more, 190 mJ / ㎠ or more, 200 mJ / ㎠ or more, 210 mJ / ㎠ or more, 220 mJ / ㎠ or more, 230 mJ / ㎠ or more, 240 mJ / ㎠ or more, 250 mJ / ㎠ or more, or 300 mJ / ㎠ or more. In addition, the upper limit may be 500 mJ / ㎠ or less or 400 mJ / ㎠ or less, specifically 350 mJ / ㎠ or less, 340 mJ / ㎠ or less, 320 mJ / ㎠ or less, 310 mJ / ㎠ or less, or 300 mJ / ㎠ or less.

[0103] In one embodiment of the present invention, the step of curing the composition for the coating layer by irradiating light in two steps may include a first light irradiation step of inducing wrinkles on the surface of the coated composition for the coating layer by irradiating light with a wavelength of 200 nm or less under nitrogen gas (N2) conditions, and a second light irradiation step of forming an ultraviolet cured coating layer by irradiating light with a wavelength of 200 nm to 450 nm onto the composition on which wrinkles are induced on the surface.

[0104] The first light irradiation step above can be performed in a nitrogen (N2) atmosphere containing a small amount of oxygen (O2) using light with a wavelength of 200 nm or less having high energy, specifically 100 nm to 200 nm or 150 nm to 195 nm. Specifically, in the first light irradiation step, the concentration of oxygen (O2) contained in nitrogen (N2) may be 10 ppm to 30,000 ppm, and specifically, 10 ppm to 20,000 ppm, 10 ppm to 5,000 ppm, 1,000 ppm to 2,000 ppm, 2,000 ppm to 3,000 ppm, 3,000 ppm to 4,000 ppm, 4,000 ppm to 5,000 ppm, 10 ppm to 2,000 ppm, 10 ppm to 1,000 ppm, 10 ppm to 500 ppm, 100 ppm to 300 ppm, 10 ppm to 200 ppm, 50 ppm to 150 ppm, 80 ppm to 120 ppm, It may be 4,000 ppm to 6,000 ppm, 4,500 ppm to 5,500 ppm, or 4,800 ppm to 5,200 ppm. Additionally, in the first light irradiation step, the distance between the composition for the coating layer and the light source may be 5 to 100 mm, and specifically, 5 to 80 mm, 5 to 60 mm, 5 to 40 mm, 10 to 70 mm, 10 to 50 mm, 10 to 30 mm, 20 to 80 mm, 20 to 60 mm, 20 to 50 mm, 20 to 30 mm, 25 to 75 mm, 50 to 80 mm, 40 to 60 mm, or 45 to 55 mm.

[0105] In addition, the amount of light irradiation in the first light irradiation step may be 25 mJ / ㎠ to 75 mJ / ㎠, specifically 25 mJ / ㎠ to 70 mJ / ㎠, 25 mJ / ㎠ to 50 mJ / ㎠, 50 mJ / ㎠ to 75 mJ / ㎠, 40 mJ / ㎠ to 60 mJ / ㎠, 25 mJ / ㎠ to 45 mJ / ㎠, 35 mJ / ㎠ to 45 mJ / ㎠, or 38 mJ / ㎠ to 43 mJ / ㎠.

[0106] As one example, the first light irradiation step can be performed by irradiating the composition with light having a wavelength of 172 ± 5 nm for a very short time of 1 to 2 seconds with a light intensity of 25 to 45 mJ / cm² (i.e., light irradiation amount) under nitrogen (N2) conditions containing 200 ppm of oxygen (O2) to cure the composition for the coating layer.

[0107] The present invention allows for easy control of the average diameter, height, and / or frequency of dense wrinkle shapes formed on the surface of a UV-cured coating layer by controlling the gas conditions, the distance between the composition for the coating layer and the light source, and / or the amount of light irradiation within the above ranges when performing the first light irradiation step, and prevents the UV-cured coating layer from easily breaking at low temperatures due to an excessive increase in curing density.

[0108] In addition, the second light irradiation step is a step of performing true curing by additionally irradiating ultraviolet (UV) light onto a composition for a pre-cured coating layer and / or an ultraviolet-cured coating layer, and can be performed in an air atmosphere using light with a wavelength of 200 nm to 450 nm, specifically 200 nm to 400 nm, 250 nm to 380 nm, 280 nm to 380 nm, 250 nm to 350 nm, or 280 nm to 320 nm. A composition in which wrinkles are formed on its surface while curing is achieved only to a certain level by the first light irradiation step can be cured in the thickness direction by undergoing a second light irradiation step in which relatively long wavelengths are irradiated.

[0109] When performing the second light irradiation step, the distance between the composition and the light source, that is, the distance from the surface of the coated composition to the light source, may be 50 mm or less, 40 mm or less, 30 mm or less, or 20 mm or less. Specifically, the upper limit of the distance may be 19 mm or less, 18 mm or less, 17 mm or less, 16 mm or less, 15 mm or less, 14 mm or less, 13 mm or less, 12 mm or less, 11 mm or less, or 10 mm or less, and the lower limit may be 0.5 mm or more, 1 mm or more, 2 mm or more, 3 mm or more, 4 mm or more, or 5 mm or more. When performing the second light irradiation step, the distance between the composition and the light source may be smaller than that during the first light irradiation step. When adjusting the distance between the composition and the light source to the above range during the second light irradiation step, it is advantageous to increase the degree of curing of the entire coating layer.

[0110] The amount of light irradiated in the second light irradiation step may be greater than the amount of light irradiated in the first light irradiation step. For example, the amount of light irradiated in the second light irradiation step may be 150 mJ / ㎠ or more, specifically 160 mJ / ㎠ or more, 170 mJ / ㎠ or more, 180 mJ / ㎠ or more, 190 mJ / ㎠ or more, 200 mJ / ㎠ or more, 210 mJ / ㎠ or more, 220 mJ / ㎠ or more, 230 mJ / ㎠ or more, 240 mJ / ㎠ or more, 250 mJ / ㎠ or more, or 300 mJ / ㎠ or more. In addition, the upper limit may be 500 mJ / ㎠ or less or 400 mJ / ㎠ or less, specifically 350 mJ / ㎠ or less, 340 mJ / ㎠ or less, 320 mJ / ㎠ or less, 310 mJ / ㎠ or less, or 300 mJ / ㎠ or less. When the amount of light irradiation is adjusted to the above range during the second light irradiation, it is advantageous to increase the degree of curing of the entire coating layer.

[0111] As described above, when the first light irradiation step and the second light irradiation step are performed, the surface of the coating layer may have a relatively dense curing density.

[0112] The light irradiated in the present invention may be irradiated according to known methods capable of irradiating light of the required wavelength at each step. For example, light having a wavelength of 400 nm or less in the UV region may be irradiated using a mercury or metal halide lamp, etc.

[0113] In addition, the time during which light is irradiated in the present invention may be a very short time of 1 to 2 seconds, and this light irradiation time may be controlled by the speed at which the composition moves when irradiated with light, for example, the speed of movement of the composition coated on the transparent layer. For example, the speed of movement of the coating layer composition and / or the transparent layer coated with the composition may be 1 to 50 m / min, and specifically, 5 to 40 m / min, 10 to 40 m / min, 20 to 40 m / min, 30 to 40 m / min, 15 to 25 m / min, 5 to 15 m / min, 15 to 20 m / min, 35 to 40 m / min, or 18 to 22 m / min.

[0114] In one embodiment of the present invention, the step of curing the composition for the coating layer by irradiating light in three steps may additionally include a first' light irradiation step of activating the composition for the coating layer by irradiating light with a wavelength of 200 nm to 450 nm in air prior to the first light irradiation step of the aforementioned two-step curing step.

[0115] The above first light irradiation step is a step of pre-curing a coated coating layer composition by applying ultraviolet (UV) energy, and can be performed by irradiating light with a wavelength of 200 nm to 450 nm, specifically 200 nm to 400 nm, 250 nm to 380 nm, 280 nm to 380 nm, 250 nm to 350 nm, or 280 nm to 320 nm under air conditions.

[0116] As described above, the ultraviolet curing process has a step of curing the composition for the coating layer by irradiating it with short wavelength light of a specific range under different conditions in one, two, or three steps.

[0117] Hereinafter, the present invention will be described in detail with reference to examples in order to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the invention to those with average knowledge in the art.

[0118] <Experimental Example 1>

[0119] A base layer with a thickness of 200 μm containing polyvinyl chloride resin (LG Chem, LS100) was prepared. The base layer was processed into a sheet in the Dark Grey color by including a black inorganic pigment.

[0120] A transparent layer was prepared by forming a 53 μm thick high weather-resistant acrylic film (manufacturer: S-Polytech (Korea)) containing ultraviolet absorbers (Tinuvin 479 and UV 328) on the above base layer.

[0121] After preparing a coating layer composition as shown in Table 1 below, the coating layer composition was applied onto the transparent layer using a gravure roll coater, and while moving the film at a moving speed of 20 ± 1 m / min, light irradiation was performed stepwise as shown in Table 2 below to produce a decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer.

[0122] [Table 1]

[0123]

[0124] The ingredients used in Table 1 above are as follows.

[0125] Monofunctional monomer: isobornyl acrylate

[0126] Bifunctional monomer: tricyclodecane dimethanol diacrylate

[0127] Trifunctional oligomer: PU3450 (Miwon Specialty Chemical, Mw 6,700) (aliphatic trifunctional urethane acrylate oligomer)

[0128] Bifunctional oligomer: PU2100 (Miwon Specialty Chemical, 1,400) (aliphatic trifunctional urethane acrylate oligomer)

[0129] UV absorber: Tinuvin 928 (BASF, triazole-based UV absorber)

[0130] Light Stabilizer: STAB LA-72 (ADEKA, hindered amine light stabilizer)

[0131] Inorganic particles: EXP 8018-1 (wax-treated precipitated silica, Evonik)

[0132] Photoinitiator: Omirad 184 (1-hydroxycyclohexyl-phenyl ketone, BASF)

[0133] [Table 2]

[0134]

[0135] <Experimental Example 2>

[0136] A decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer was prepared by performing the same procedure as Experimental Example 1 above, except that a composition for the coating layer as shown in Table 3 below was used.

[0137] [Table 3]

[0138]

[0139] The ingredients used in Table 3 above are as follows.

[0140] Monofunctional monomer: Tetrahydrofurfuryl Acrylate

[0141] Difunctional monomer: 1,6-Hexenediol diacrylate

[0142] Trifunctional oligomer: PU330 (Miwon Specialty Chemical, Mw 1,700) (aliphatic trifunctional urethane acrylate oligomer)

[0143] Bifunctional oligomer: PU2100 (Miwon Specialty Chemical, 1,400) (aliphatic trifunctional urethane acrylate oligomer)

[0144] UV absorber: Tinuvin 928 (BASF, triazole-based UV absorber)

[0145] Light Stabilizer: STAB LA-72 (ADEKA, hindered amine light stabilizer)

[0146] Inorganic particles: EXP 8018-1 (wax-treated precipitated silica, Evonik)

[0147] Photoinitiator: Omirad 184 (1-hydroxycyclohexyl-phenyl ketone, BASF)

[0148] <Experimental Example 3>

[0149] A decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer was prepared by performing the same procedure as Experimental Example 1, except that a composition for the coating layer as shown in Table 4 below was used.

[0150] [Table 4]

[0151]

[0152] The ingredients used in Table 4 above are as follows.

[0153] Monofunctional monomer: isobornyl acrylate

[0154] Bifunctional monomer: tricyclodecane dimethanol diacrylate

[0155] Trifunctional oligomer: PU3450 (Miwon Specialty Chemical, Mw 6,700) (aliphatic trifunctional urethane acrylate oligomer)

[0156] Bifunctional oligomer: PU2100 (Miwon Specialty Chemical, 1,400) (aliphatic trifunctional urethane acrylate oligomer)

[0157] UV absorber: UV 384-2 (Baoxu Chemical, triazole-based UV absorber)

[0158] Light Stabilizer: STAB LA-72 (ADEKA, hindered amine light stabilizer)

[0159] Inorganic particles: EXP 8018-1 (wax-treated precipitated silica, Evonik)

[0160] Photoinitiator: Omirad 184 (1-hydroxycyclohexyl-phenyl ketone, BASF)

[0161] <Experimental Example 4>

[0162] A decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer was prepared by performing the same procedure as Experimental Example 1, except that a composition for the coating layer as shown in Table 5 below was used.

[0163] [Table 5]

[0164]

[0165] The ingredients used in Table 5 above are as follows.

[0166] Monofunctional monomer: isobornyl acrylate

[0167] Bifunctional monomer: tricyclodecane dimethanol diacrylate

[0168] Trifunctional oligomer: PU3450 (Miwon Specialty Chemical, Mw 6,700) (aliphatic trifunctional urethane acrylate oligomer)

[0169] Bifunctional oligomer: PU2100 (Miwon Specialty Chemical, 1,400) (aliphatic trifunctional urethane acrylate oligomer)

[0170] UV absorber: UV 384-2 (Baoxu Chelmcal, triazole-based UV absorber)

[0171] Light Stabilizer: UV 292 (Baoxu Chemical, hindered amine light stabilizer)

[0172] Inorganic particles: EXP 8018-1 (wax-treated precipitated silica, Evonik)

[0173] Photoinitiator: Omirad 184 (1-hydroxycyclohexyl-phenyl ketone, BASF)

[0174] <Experimental Example 5>

[0175] A decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer was prepared by performing the same procedure as Experimental Example 1, except that a composition for the coating layer as shown in Table 6 below was used and light irradiation was performed under conditions as shown in Table 7 below.

[0176] [Table 6]

[0177]

[0178] The ingredients used in Table 6 above are as follows.

[0179] Monofunctional monomer: isobornyl acrylate

[0180] Bifunctional monomer: tricyclodecane dimethanol diacrylate

[0181] Trifunctional oligomer: PU3450 (Miwon Specialty Chemical, Mw 6,700) (aliphatic trifunctional urethane acrylate oligomer)

[0182] Bifunctional oligomer: PU2100 (Miwon Specialty Chemical, 1,400) (aliphatic trifunctional urethane acrylate oligomer)

[0183] UV absorber: Tinuvin 928 (BASF)

[0184] Light stabilizer: STAB LA-72 (ADEKA)

[0185] Photoinitiator: Omirad 184 (1-hydroxycyclohexyl-phenyl ketone, BASF)

[0186] [Table 7]

[0187]

[0188] <Experimental Example 6>

[0189] A decorative sheet comprising a base layer and a transparent layer was manufactured by performing the same procedure as in Experimental Example 1, excluding the above UV-cured coating layer.

[0190] <Experimental Example 7>

[0191] When preparing the composition for the coating layer above, both the ultraviolet absorber and the light stabilizer were excluded, and the process was carried out in the same manner as Experimental Example 1 above to produce a decorative sheet comprising a base layer, a transparent layer, and an ultraviolet curing coating layer.

[0192] <Experimental Example 8>

[0193] A decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer was prepared by performing the same procedure as Experimental Example 1, except that Tinuvin 477, a triazine-based UV absorber, was used instead of Tinuvin 928, a triazole-based UV absorber, when preparing the composition for the coating layer.

[0194] <Experimental Example 9>

[0195] A decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer was prepared by performing the same procedure as in Experimental Example 1, except that when preparing the composition for the coating layer, Tinuvin 477, a triazine-based UV absorber, was used instead of Tinuvin 928, a triazole-based UV absorber, and Irganox 1135, a phenol-based light stabilizer, was used instead of STAB LA-72, a hindered amine-based light stabilizer.

[0196] <Experimental Example 10>

[0197] A decorative sheet comprising a base layer, a transparent layer, and a UV-cured coating layer was prepared by performing the same procedure as Experimental Example 1, except that a composition for the coating layer as shown in Table 8 below was used.

[0198] [Table 8]

[0199]

[0200] The ingredients used in Table 8 above are the same as those in Experimental Example 1 above.

[0201] The coating layer composition applied in Experimental Example 10 above had an excessively high content of UV absorbers and light stabilizers, so the UV rays irradiated during the curing process of the coating layer were absorbed, and the curing reaction of the coating layer was not sufficiently carried out, resulting in tackiness on the surface of the coating layer and a decrease in adhesion.

[0202] <Experimental Example 11>

[0203] Weather resistance evaluation was performed on the decorative sheets prepared in Experimental Examples 1 to 9 above. The weather resistance evaluation was conducted using an ultra-fast accelerated test method under very harsh conditions as described in Method 2 below, and the color difference (△E) of the surface of the decorative sheet was evaluated in 100-hour increments up to 500 hours, and the results are shown in Table 9 below. The color difference (△E) was calculated according to Equation 2 below after measuring the colors (L*, a*, b*) before and after the weather resistance evaluation according to the ultra-fast accelerated test method using a colorimeter. However, since the decorative sheet of Experimental Example 6 does not contain a UV-cured coating layer, the color difference (△E) of the surface of the transparent layer was evaluated.

[0204] [Method 2]

[0205] A metal-halide lamp equipped with a UVCF10 filter was irradiated with ultraviolet and visible light in the range of 295 nm to 800 nm onto the decorative sheet, and the hourly irradiation dose of ultraviolet and visible light was 5.4 mJ / cm² 2 The temperature of the Black Standard was set to 63℃ and the relative humidity to 63%, and

[0206] After measuring the colors (L*, a*, b*) around 500 hours using a colorimeter, the color difference (△E) of the surface of the decorative sheet was calculated according to the following mathematical formula 2.

[0207] [Mathematical Formula 2]

[0208] △E = [(△L*) 2 + (△a*) 2 + (△b*) 2 ]1 / 2

[0209] In addition, the glossiness of the surface of the UV-cured coating layer of the decorative sheets prepared in Experimental Examples 1 to 9 was measured under a gloss of 60° and is shown in Table 9 below. However, since the decorative sheet of Experimental Example 6 does not contain a UV-cured coating layer, the glossiness of the surface of the transparent layer under a gloss of 60° was measured. The glossiness under the gloss of 60° was measured using a gloss meter (BYK) in accordance with ASTM D2457.

[0210] [Table 9]

[0211]

[0212] As shown in the results above, in the case of Experimental Examples 1 to 5 of the present invention, when evaluating weather resistance according to Method 1, it can be confirmed that the color difference (△E) of the UV-cured coating layer is 1.0 or less after 100 hours, 2.3 or less after 300 hours, 2.9 or less after 400 hours, and 3.5 or less after 500 hours. However, in the case of Experimental Examples 6 to 9, the color difference value of the UV-cured coating layer of the present invention was not satisfied.

[0213] Accordingly, according to the present invention, by including a UV-curing coating layer in the decorative sheet, the yellowing phenomenon of the decorative sheet can be suppressed even during prolonged UV irradiation, thus providing a decorative sheet with excellent weather resistance that can be applied as an exterior building material.

[0214] <Experimental Example 12>

[0215] After the decorative sheet prepared in Experimental Example 1 above was subjected to accelerated aging treatment by leaving it in a 60°C oven for 30 days, the change in the content of the UV absorber included in the UV-cured coating layer was evaluated using the following Raman spectroscopy method, and the results are shown in Figure 3 below.

[0216] Raman Spectroscopic Analysis of UV-Curing Coating Layers

[0217] A cross-section of the decorative sheet was fabricated, and the Raman spectrum of the UV-cured coating layer was measured using a 785 nm laser as a light source. At this time, among the Raman spectra of the UV-cured coating layer, 1305 cm⁻¹ -1 Since a peak due to the UV absorber is confirmed at 1305 cm⁻¹ -1 Peak at and 1288 cm -1 A mapping analysis of the distribution of UV absorbers was performed using the ratio of peak heights at.

[0218] In the mapping analysis image above, the higher the content of the UV absorber, the more it is represented in red, and the lower the content, the more it is represented in green.

[0219] As shown in Fig. 3 below, it can be confirmed that the UV absorber included in the UV-cured coating layer of a decorative sheet according to one embodiment of the present invention does not change in content even after the accelerated deterioration treatment of the decorative sheet.

[0220] <Experimental Example 13>

[0221] After the decorative sheet prepared in Experimental Example 6 above was subjected to accelerated aging treatment by leaving it in a 60°C oven for 30 days, the change in the content of the ultraviolet absorber contained in the transparent layer was evaluated using the Raman spectroscopy method below, and the results are shown in Fig. 4 below.

[0222] Raman Spectroscopy of the Transparent Layer

[0223] A cross-section of the decorative sheet was fabricated, and the Raman spectrum of the transparent layer was measured using a 532 nm laser as a light source. At this time, among the Raman spectrum of the transparent layer, 1610 cm⁻¹ -1 Since a peak due to the UV absorber is confirmed at 1610 cm⁻¹ -1 Peak at and 1725 cm -1A mapping analysis of the distribution of UV absorbers was performed using the ratio of peak heights at.

[0224] In the mapping analysis image above, higher UV absorber content is represented in red, while lower content is represented in green and blue.

[0225] As shown in Fig. 4 below, since the decorative sheet of Experimental Example 6 does not include a UV-cured coating layer according to one embodiment of the present invention, it can be confirmed that the content of the UV absorber present in the transparent layer after the accelerated deterioration treatment of the decorative sheet is very low.

[0226] <Experimental Example 14>

[0227] For the decorative sheet prepared in Experimental Example 1 above, an evaluation of the rate of change in the content of the UV absorber included in the UV-cured coating layer was conducted. The evaluation of the rate of change in the content of the UV absorber was performed using an accelerated evaluation method as described in Method 1 below, and the results are shown in Fig. 5 below.

[0228] [Method 1]

[0229] The above decorative sheet is subjected to accelerated heat treatment by being left in a 60℃ oven for 30 days, and

[0230] For the UV-cured coating layer before and after accelerated degradation treatment, the peak area per weight (area / mg) of the UV absorber was calculated from the graph analyzed by Pyro-Gas Chromatography / Mass Spectrometry (Pyro-GCMS), and the rate of change in the content of the UV absorber was calculated according to the following Equation 1.

[0231] [Mathematical Formula 1]

[0232] Rate of change in UV absorber content (%) = [(Peak area per weight of UV absorber before accelerated degradation treatment - Peak area per weight of UV absorber after accelerated degradation treatment) / (Peak area per weight of UV absorber before accelerated degradation treatment)] × 100

[0233] <Pyrolysis Gas Chromatography Mass Spectrometry of UV-Curing Coating Layers>

[0234] Pyro-GCMS analysis method

[0235] - Equipment Specs: Frointier Lab PY-3030D / Agilent 7890B / 5977B

[0236] - Pyrolysis temperature: 600℃, 10min

[0237] - UA-5 column, 30m × 250㎛ × 0.25㎛

[0238] - 40℃ for 2min, 20℃ / min to 310℃ for 14min

[0239] - SIM mode, 133, 203m / z

[0240] - Confirm identical detection location using SIM mode measurement data

[0241] In the graph analyzed by Pyro-GCMS, a thermal decomposition peak of the UV absorber was identified at a retention time of 15.0 min. Since this peak is distinguishable from the thermal decomposition peaks of other components, the change in the content of the UV absorber contained in the UV-cured coating layer was quantitatively analyzed using the area of ​​this peak. As shown in the results of Figure 5 below, the peak area per weight (area / mg) of the UV absorber before accelerated degradation treatment was measured as 2.23E+06 area / mg, and the peak area per weight (area / mg) of the UV absorber after accelerated degradation treatment was measured as 2.22E+06 area / mg.

[0242] The rate of change in the content of the ultraviolet absorber according to the above mathematical formula 1 was approximately 0.45%.

[0243] As shown in the above results, it can be confirmed that the content of the UV absorber included in the UV-cured coating layer of the decorative sheet according to one embodiment of the present invention does not change even after the accelerated deterioration treatment of the decorative sheet.

[0244] As shown in the above results, according to the present invention, by including a UV-curing coating layer in the decorative sheet, the yellowing phenomenon of the decorative sheet can be suppressed even during prolonged UV irradiation, thereby providing a decorative sheet with excellent weather resistance that can be applied as an exterior building material.

[0245] In addition, the decorative sheet according to the present invention can have its surface gloss adjusted to glossy, matte, etc., depending on the manufacturing process of the UV-cured coating layer, so it can be applied to various products.

Claims

1. A base layer; a transparent layer provided on the base layer; and a UV-curing coating layer provided on the transparent layer, comprising The above UV-curing coating layer comprises an acrylic resin and a UV absorber, and A decorative sheet having a change rate in the content of a UV absorber included in the UV-cured coating layer of 10% or less when evaluated according to the following method 1: [Method 1] The above decorative sheet is subjected to accelerated heat treatment by being left in a 60℃ oven for 30 days, and For the UV-cured coating layer before and after accelerated degradation treatment, the peak area per weight (area / mg) of the UV absorber was calculated from the graph analyzed by pyrolysis gas chromatography mass spectrometry (Pyro-GCMS), and the rate of change in the content of the UV absorber was calculated according to the following mathematical formula 1. [Mathematical Formula 1] Rate of change in UV absorber content (%) = [(Peak area per weight of UV absorber before accelerated degradation treatment - Peak area per weight of UV absorber after accelerated degradation treatment) / (Peak area per weight of UV absorber before accelerated degradation treatment)] × 100 2. A decorative sheet according to claim 1, wherein the UV-curing coating layer further comprises a light stabilizer.

3. A decorative sheet according to claim 2, wherein the ultraviolet absorber is a triazole-based ultraviolet absorber and the light stabilizer is a hindered amine-based light stabilizer.

4. A decorative sheet according to Claim 1, wherein, when weathering resistance is evaluated according to the following Method 2, the color difference (△E) of the UV-cured coating layer is 3.5 or less: [Method 2] A metal-halide lamp equipped with a UVCF10 filter was irradiated with ultraviolet and visible light in the range of 295 nm to 800 nm onto the decorative sheet, and the hourly irradiation dose of ultraviolet and visible light was 5.4 mJ / cm² 2 The temperature of the Black Standard was set to 63℃ and the relative humidity to 63%, and After measuring the colors (L*, a*, b*) around 500 hours using a colorimeter, the color difference (△E) of the surface of the decorative sheet was calculated according to the following mathematical formula 1. [Mathematical Formula 2] △E = [(△L*) 2 + (△a*) 2 + (△b*) 2 ] 1 / 2 5. A decorative sheet according to Claim 1, wherein the gloss level of the surface of the UV-cured coating layer under a gloss 60° condition is 10 or less.

6. A decorative sheet according to Claim 1, wherein the gloss level of the surface of the UV-cured coating layer under a gloss 60° condition is 20 or higher.

7. A decorative sheet according to claim 1, wherein the surface of the UV-cured coating layer has a wrinkled structure, and the surface roughness (Rz) of the UV-cured coating layer is 1 μm to 10 μm.

8. A decorative sheet according to claim 1, wherein the base layer comprises polyvinyl chloride resin.

9. A decorative sheet according to claim 1, wherein the transparent layer comprises one or more of polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF).

10. A decorative sheet according to claim 9, wherein the transparent layer further comprises one or more of a UV absorber and a light stabilizer.

11. A decorative sheet according to claim 1, wherein the UV-curing coating layer is provided in direct contact with the transparent layer.

12. In any one of claims 1 to 11, the decorative sheet is a decorative sheet for use as an exterior material for a building.

13. Step of preparing the base layer; A step of forming a transparent layer on the above base layer; and A step of forming a UV-cured coating layer by applying a coating layer composition comprising an acrylic resin, a triazole-based UV absorber, and a hindered amine-based light stabilizer onto the above transparent layer, and then performing a UV curing process. A method for manufacturing a decorative sheet according to any one of claims 1 to 11, comprising 14. A method for manufacturing a decorative sheet according to claim 13, wherein the ultraviolet curing process comprises the step of curing the composition for the coating layer by irradiating it with short-wavelength light in one step, or curing it by irradiating it in two or three steps under different conditions.

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