Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/16—Layered products comprising a layer of synthetic resin specially treated, e.g. irradiated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
  • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
  • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
  • B32B3/30—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer formed with recesses or projections, e.g. hollows, grooves, protuberances, ribs

Definitions

• the present invention relates to a decorative sheet.
• Decorative sheets are used to decorate the surfaces of interior and exterior materials such as building fixtures, furniture, fixtures, and flooring, for the purpose of imparting design and durability to these components.
• Decorative sheets are generally widely used as decorative panels that are attached via adhesives to the surface of substrates such as wood, wood boards, metal plates, non-flammable boards, paper substrates, and resin substrates.
• Designs can be added by using various printing methods to create patterns such as wood grain or stone grain. Plain decorative sheets without patterns are sometimes preferred. The choice of whether or not to have a pattern and the type of pattern varies depending on the application and preference.
• the texture is also important to the design of decorative sheets. For example, there is a demand for decorative sheets that have a texture similar to that obtained when wood is planed to create a highly smooth surface and then the planed surface is lightly rubbed with coarse sandpaper, i.e., a texture that is smooth yet has a texture that differs from that of a completely smooth surface.
• this type of texture will also be referred to as the "sanding feel.”
• durability is an important function of decorative sheets, along with providing design. Durability is a comprehensive assessment of scratch resistance, stain resistance, and whether these properties can be maintained over the long term. Requirements vary depending on the environment and situation in which the decorative sheet is used, but there is always a demand for decorative sheets with high performance.
• a surface protective layer on the outermost surface of the decorative sheet. Furthermore, to adjust the aforementioned gloss, particularly to achieve a low gloss, it is common to add a gloss adjuster (matt additive) to the surface protective layer.
• one example of a decorative sheet that takes into consideration design (low gloss), scratch resistance, and stain resistance is the decorative sheet described in Patent Document 1.
• the object of the present invention is to provide a decorative sheet that provides a unique feel.
• One aspect of the present invention provides a decorative sheet comprising an original fabric layer and a surface protective layer provided on one surface of the original fabric layer, wherein the surface of the surface protective layer has an uneven structure, and the uneven structure of the surface protective layer has an autocorrelation length Sal of 20 ⁇ m or less and a root-mean-square gradient Sdq of 0.1 or more.
• a decorative sheet according to the above aspect in which the convex area ratio is 40% or less.
• a decorative sheet according to any of the above aspects, wherein the surface protective layer contains a cured resin and particles.
• a decorative sheet according to the above aspect, in which the particles are contained in the surface protective layer in an amount of 5 to 10 parts by mass per 100 parts by mass of the resin.
• a decorative sheet according to any of the above aspects, wherein the resin is an ionizing radiation curable resin.
• a decorative sheet according to any of the above aspects, wherein the resin is an acrylate.
• a decorative sheet according to any of the above aspects, wherein the resin includes an acrylate having a functionality of three or less.
• a decorative sheet according to the above aspect, wherein the resin further contains a bifunctional acrylate, and the amount of the bifunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more.
• a decorative sheet according to the above aspect wherein the molecular weight of the bifunctional acrylate is within the range of 250 to 850.
• a decorative sheet according to any of the above aspects, wherein the resin further contains a pentafunctional or higher acrylate, and the amount of the pentafunctional or higher acrylate is 3 parts by mass or more and 20 parts by mass or less.
• a decorative sheet according to any of the above aspects, wherein the resin contains a tetrafunctional acrylate, the amount of the tetrafunctional acrylate per 100 parts by mass of the resin is 40 parts by mass or more, and the molecular weight of the tetrafunctional acrylate is in the range of 1800 to 2000.
• a decorative sheet according to any of the above aspects, wherein the thickness t of the surface protective layer is 3 ⁇ m or more and 10 ⁇ m or less.
• a decorative sheet according to any of the above aspects, wherein the gloss level of the surface protective layer is 5 or less.
• a decorative sheet according to any of the above aspects, further comprising a pattern layer between the base fabric layer and the surface protective layer.
• a decorative material comprising a decorative sheet according to any of the above aspects and a substrate to which the decorative sheet is attached.
• a method for producing a decorative sheet comprising: forming a coating film made of a coating liquid containing an ionizing radiation curable resin and particles on an original fabric layer; carrying out a first irradiation step in which the coating film is irradiated with light having a wavelength of 200 nm or less; and then carrying out a second irradiation step in which the coating film is irradiated with ionizing radiation or ultraviolet light having a longer wavelength than the light irradiated in the first irradiation step, wherein the first irradiation step is carried out so that the autocorrelation length Sal of the surface of the coating film after the second irradiation step is 20 ⁇ m or less and the root-mean-square gradient Sdq is 0.1 or more.
• the present invention provides a decorative sheet that provides a unique feel.
• FIG. 1 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention.
• FIG. 2 is a cross-sectional view of a surface protective layer included in the decorative sheet of FIG.
• FIG. 3 is a microscope image of a surface protective layer included in a decorative sheet according to one example of the present invention.
• Decorative material and decorative sheet Fig. 1 is a cross-sectional view of a decorative material including a decorative sheet according to one embodiment of the present invention.
• Fig. 2 is a cross-sectional view of a surface protective layer included in the decorative sheet of Fig. 1.
• Fig. 3 is a micrograph of a surface protective layer included in a decorative sheet according to one example of the present invention.
• the micrograph in Figure 3 is a planar photograph taken with a laser microscope (OLS-4000, manufactured by Olympus Corporation).
• the decorative material 11 shown in Figure 1 includes a substrate B and a decorative sheet 1 attached thereto.
• the decorative material 11 is a decorative board.
• the decorative board may be a flat plate, or may be curved or folded.
• the decorative material 11 may have a shape other than a plate.
• the substrate B is a plate material.
• the plate material is, for example, a wood board, an inorganic board, a metal plate, or a composite board made of multiple materials.
• the substrate B may also have a shape other than a plate.
• the decorative sheet 1 includes a base fabric layer 2, a design layer 3, a transparent resin layer 4, a surface protective layer 5, an adhesive layer 7, a primer layer 6, and a concealing layer 8.
• the design layer 3, adhesive layer 7, transparent resin layer 4, and surface protective layer 5 are provided in this order from the base fabric layer 2 side on the surface of the base fabric layer 2 opposite the surface facing the substrate B.
• the concealing layer 8 and primer layer 6 are provided in this order from the base fabric layer 2 side on the surface of the base fabric layer 2 facing the substrate B.
• One or more of the design layer 3, transparent resin layer 4, primer layer 6, adhesive layer 7, and concealing layer 8 may be omitted. The elements included in the decorative sheet 1 are explained below in order.
• the raw fabric layer 2 or its material can be any material selected from, for example, paper, synthetic resin, synthetic resin foam, rubber, nonwoven fabric, synthetic paper, metal foil, etc.
• paper include tissue paper, titanium paper, and resin-impregnated paper.
• synthetic resins include polyethylene, polypropylene, polybutylene, polystyrene, polycarbonate, polyester, polyamide, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and acrylic.
• Examples of rubber include ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer rubber, styrene-butadiene-styrene block copolymer rubber, and polyurethane.
• Examples of nonwoven fabric include organic and inorganic nonwoven fabrics.
• Examples of metals for the metal foil include aluminum, iron, gold, and silver.
• the thickness of the base fabric layer 2 is preferably in the range of 20 ⁇ m to 250 ⁇ m, taking into consideration printing workability and costs.
• Primer Layer When an olefin-based resin is used as the material of the raw fabric layer 2, the surface of the raw fabric layer 2 is often in an inactive state. Therefore, in this case, it is preferable to provide a primer layer 6 between the raw fabric layer 2 and the substrate B.
• the primer layer 6 may be omitted, and the raw fabric layer 2 may be subjected to a surface modification treatment such as corona treatment, plasma treatment, ozone treatment, electron beam treatment, ultraviolet treatment, or dichromate treatment in order to improve the adhesion between the raw fabric layer 2 and the substrate B.
• the materials used for the primer layer 6 can be, for example, the materials described below for the design layer 3. Since the primer layer 6 is applied to the back surface of the decorative sheet 1, and considering that the decorative sheet 1 will be wound into a web, an inorganic filler may be added to the primer layer 6 to avoid blocking and increase adhesion to the adhesive.
• inorganic fillers include silica, alumina, magnesia, titanium oxide, and barium sulfate.
• a colored sheet is used as the base layer 2, or an opaque concealing layer 8 is provided.
• the concealing layer 8 can be made of, for example, the same material as that used for the design layer 3, which will be described later.
• an opaque pigment titanium oxide, iron oxide, or the like, as the pigment.
• metals such as gold, silver, copper, and aluminum can also be added to the material of the concealing layer 8. Generally, flake-shaped aluminum pieces are often added.
• the design layer 3 is a layer formed by printing a design onto the base layer 2 using ink.
• ink binders include soluble nitrocellulose, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, polyesters, and modified versions thereof, either alone or in combination.
• the binder may be aqueous, solvent-based, or emulsion-based, and may be a one-component type or a two-component type incorporating a curing agent.
• the design layer 3 may be formed by curing a layer formed with a curable ink by exposure to ultraviolet light, electron beams, or the like.
• the most common method is to use a urethane-based ink that is cured with an isocyanate.
• the ink used to form the design layer 3 may further contain, in addition to the binder, pigments and colorants such as dyes, extender pigments, solvents, and various additives typically found in inks.
• pigments and colorants such as dyes, extender pigments, solvents, and various additives typically found in inks.
• versatile pigments include condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, and pearl pigments such as mica.
• the ink contains a light stabilizer. This prevents deterioration of the decorative sheet 1 itself due to light degradation of the ink, thereby extending the life of the decorative sheet 1.
• the pattern layer 3 is provided between the base fabric layer 2 and the adhesive layer 7, but it can be provided at any position between the base fabric layer 2 and the surface protection layer 5.
• the pattern layer 3 has, for example, a wood grain pattern. When the pattern layer 3 has a wood grain pattern, the user can get a wood-like tactile sensation from the visual information.
• the pattern layer 3 may also be omitted.
• Adhesive Layer 7 is also called a heat-sensitive adhesive layer, an anchor coat layer, or a dry lamination adhesive layer.
• the resin material for adhesive layer 7 is not particularly limited, but can be appropriately selected from acrylic, polyester, polyurethane, and epoxy resin materials. Furthermore, ethylene-vinyl acetate copolymer resin adhesives can also be used as the resin material for adhesive layer 7.
• the coating method can be appropriately selected depending on the viscosity of the adhesive. Generally, gravure coating is used, and after forming adhesive layer 7 on the top surface of design layer 3 by gravure coating, transparent resin layer 4 is laminated. Note that adhesive layer 7 can be omitted if sufficient adhesive strength can be obtained between transparent resin layer 4 and design layer 3.
• An olefin-based resin is preferably used as the resin material for the transparent resin layer 4.
• the olefin-based resin include polypropylene, polyethylene, polybutene, and the like, as well as ⁇ -olefins (e.g., propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1
• the resin for the transparent resin layer 4.
• various additives such as heat stabilizers, light stabilizers, antiblocking agents, catalyst scavengers, colorants, light scattering agents, and gloss adjusters can also be added to the transparent resin layer 4 as needed.
• Phenol-based, sulfur-based, phosphorus-based, and hydrazine-based heat stabilizers are commonly used, while hindered amine-based and other light stabilizers are commonly used, each added in any combination.
• the surface protection layer 5 includes a core portion 5A and a plurality of ridge portions 5B each protruding in a ridge shape from one surface of the core portion 5A. These ridge portions 5B form an uneven structure.
• the term "ridge-like” refers to a convex shape that is linear in plan view.
• the ridge portions 5B may be curved or linear in plan view, but curved shapes are preferable from the standpoint of the fingerprint resistance of the decorative sheet 1.
• Each ridge portion 5B may or may not be branched in plan view.
• the ridge portions 5B refer to, for example, the portion from the lowest point to the tip of the uneven shape provided on the surface of the surface protective layer 5, and the core portion 5A refers to the portion of the surface protective layer 5 excluding the ridge portions 5B.
• the ridge portions 5B are each curved, and at least some of them are adjacent to each other in the width direction.
• the cross section of the surface protection layer 5 parallel to this width direction and the thickness direction of the surface protection layer 5 has a wave shape, such as a sine wave shape, in the portion where the uneven structure is provided, as shown in Figure 2.
• the surface protective layer 5 covers the entire upper surface of the underlying layer (transparent resin layer 4 in this embodiment) that contacts the surface protective layer 5.
• the underlying layer i.e., transparent resin layer 4
• the surface protective layer 5 is not exposed on the surface.
• the uneven structure of the surface protection layer 5 has an autocorrelation length Sal of 20 ⁇ m or less.
• the autocorrelation length Sal is, for example, 5.5 ⁇ m or more.
• the autocorrelation length Sal is preferably 5.5 ⁇ m or more and 15.0 ⁇ m or less, and more preferably 5.5 ⁇ m or more and 7.4 ⁇ m or less.
• the autocorrelation length Sal is the shortest distance at which the autocorrelation function decays to 0.2.
• the autocorrelation function is a function that indicates the correlation between a certain surface texture surface and a surface texture surface obtained by shifting that surface texture surface by (tx, ty) in the reference region (A).
• the autocorrelation length represents the period of the uneven structure.
• the autocorrelation length Sal is large, gentle unevenness predominates in the uneven structure.
• the autocorrelation length Sal is small, steep unevenness predominates in the uneven structure. Therefore, when the autocorrelation length Sal is within the above range, the uneven structure has a fine mesh.
• the autocorrelation length Sal is a surface texture parameter defined in ISO 25178-2:2021.
• the uneven structure of the surface protection layer 5 has a root-mean-square gradient Sdq of 0.1 or more.
• the root-mean-square gradient Sdq is, for example, 0.4 or less.
• the root-mean-square gradient Sdq is preferably 0.15 or more and 0.6 or less, and more preferably 0.27 or more and 0.6 or less.
• the root-mean-square gradient Sdq is the root-mean-square of the local gradient in a reference area.
• the root-mean-square gradient Sdq is a parameter that can be used to evaluate the magnitude of the local gradient. Specifically, the root-mean-square gradient Sdq quantifies the steepness of the convex or concave portions contained in the uneven structure. The larger the root-mean-square gradient Sdq, the steeper the gradient of the convex or concave portions.
• the root-mean-square gradient Sdq is a surface texture parameter specified in ISO 25178-2:2021.
• the root mean square gradient Sdq is expressed by the following equation 1.
• A indicates the reference area.
• the uneven structure of the surface protection layer 5 has a convex area ratio of 40% or less, as described below.
• the convex area ratio is, for example, 30% or less.
• the convex area ratio is preferably 25% or more and 34% or less, and more preferably 25% or more and 30% or less.
• the convex area ratio is a numerical value expressed in percent by the following formula 2.
• Convex area ratio (Smr1/100) ⁇ V/Spk/S ⁇ 100 Equation 2
• Smr1 is the area load ratio in percent at the point where the line separating the protruding peaks of the evaluation area from the core of the profile curve intersects with the load curve.
• the area load ratio Smr1 is preferably 7% or more and 30% or less, and more preferably 15% or more and 30% or less.
• Smr1 is a surface texture parameter specified in ISO 25178-2:2021.
• V is the volume of the entire shape at or above the minimum height in the evaluation region.
• the volume V is, for example, 0.21 mm3 or more and 1.2 mm3 or less.
• the volume V can be measured by integrating the height of the entire region based on the minimum height of the shape image obtained by the laser microscope.
• the average height Spk of the protruding peaks is preferably 0.8 ⁇ m or more and 5.1 ⁇ m or less, and more preferably 2.5 ⁇ m or more and 5.1 ⁇ m or less.
• the average height Spk of the protruding peaks is a surface texture parameter specified in ISO 25178-2:2021.
• the surface area S is the surface area of the evaluation region.
• the surface area S is preferably 0.08 mm 2 or more and 0.14 mm 2 or less, and more preferably 0.1 mm 2 or more and 0.14 mm 2 or less.
• the surface area S is expressed by the following formula 3.
• A is the reference region.
• the convex area ratio is equivalent to the ratio, expressed as a percentage, of the total area of the upper surfaces of the multiple convex portions contained in the concave-convex structure, assuming that each of the convex portions is a rectangular parallelepiped, to the area of the concave-convex structure itself.
• the thickness t of the surface protective layer 5 is preferably 10 ⁇ m or less. It is more preferable that the thickness t of the surface protective layer 5 is 3 ⁇ m or more and 10 ⁇ m or less. If the thickness of the surface protective layer 5 is too small or too large, it becomes difficult to achieve a "sanding feel."
• the thickness of the surface protective layer 5 is determined by observing the cross section with a scanning electron microscope and averaging the values at 25 points. Specifically, the thickness of the surface protective layer 5 can be determined as described in the examples below. Note that if the surface protective layer coating liquid described below does not contain a solvent, the thickness of the coating film made from the surface protective layer coating liquid will be equal to the thickness of the surface protective layer 5.
• the surface protective layer 5 preferably contains a cured resin and particles.
• the resin contained in the surface protection layer 5 is preferably an ionizing radiation curable resin.
• ionizing radiation refers to a charged particle beam such as an electron beam.
• the ionizing radiation curable resin is cured by irradiation with ionizing radiation.
• the ionizing radiation curable resin can also be cured by irradiation with ultraviolet light.
• the ionizing radiation curable resin used here is cured by irradiation with light having a wavelength of 200 nm or less, and has a large absorption coefficient for this light.
• the amount of cured ionizing radiation curable resin in the surface protective layer 5 is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.
• the ionizing radiation curable resin may be any known resin, such as various monomers or commercially available oligomers. For example, (meth)acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, or epoxy resins may be used.
• the ionizing radiation curable resin may be either an aqueous resin or a non-aqueous (organic solvent-based) resin.
• the main component of the ionizing radiation curable resin is preferably an acrylate.
• the main component of the ionizing radiation curable resin means a component that accounts for 60% or more by mass in the ionizing radiation curable resin.
• the ionizing radiation curable resin preferably contains 70 parts by mass or more of acrylate, and more preferably 80 parts by mass or more.
• the ionizing radiation curable resin is more preferably an acrylate.
• the acrylate preferably contains a tri- or lower functional acrylate.
• the proportion of tri- or lower functional acrylate per 100 parts by mass of ionizing radiation curable resin is preferably 50 parts by mass or more, and more preferably 70 parts by mass or more. The above proportion is, for example, 90 parts by mass or less. If the amount of tri- or lower functional acrylate is too small, it is difficult to achieve a sanded feel. Furthermore, in this case, reflections are likely to occur when the user looks at the decorative sheet 1.
• the acrylate preferably contains a trifunctional acrylate.
• the proportion of the trifunctional acrylate per 100 parts by mass of the ionizing radiation curable resin is preferably 40 parts by mass or more, and more preferably 60 parts by mass or more. The above proportion is, for example, 90 parts by mass or less.
• the acrylate preferably contains a difunctional acrylate in addition to a trifunctional acrylate.
• the proportion of the difunctional acrylate per 100 parts by mass of the ionizing radiation curable resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 40 parts by mass or more.
• the above proportion is, for example, 80 parts by mass or less.
• the acrylate comprises a difunctional acrylate and a trifunctional acrylate.
• the proportion of the trifunctional acrylate per 100 parts by mass of the ionizing radiation curable resin is preferably 40 parts by mass or more and 90 parts by mass or less. In this way, it is preferable that the acrylate contains multiple acrylates with different numbers of functional groups.
• the acrylate preferably contains a pentafunctional or higher acrylate in addition to a trifunctional or lower acrylate.
• the proportion of the pentafunctional or higher acrylate per 100 parts by mass of the ionizing radiation curable resin is preferably 3 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 10 parts by mass or less.
• the acrylate comprises a trifunctional acrylate and a pentafunctional or higher acrylate.
• the pentafunctional or higher acrylate is, for example, a pentafunctional or hexafunctional acrylate.
• the acrylate may contain a tetrafunctional acrylate.
• the proportion of the tetrafunctional acrylate per 100 parts by mass of the ionizing radiation curable resin is, for example, 40 parts by mass or more. This proportion is, for example, 80 parts by mass or less.
• the acrylate preferably contains a repeating structure.
• This repeating structure is, for example, an ethylene oxide (EO) structure, a propylene oxide (PO) structure, or an ⁇ -caprolactone (CL) structure.
• the repeating structure is preferably ethylene oxide or propylene oxide.
• the repeating structure may be in an open ring state and interposed between the acryloyl group and the methylol group.
• the number of repetitions in the repeating structure is preferably 3 or more per acryloyl group. However, when the number of functional groups is 2 or less, it is preferable that it is uniformly 3 or more. If an acrylate with a high number of repetitions is used, the cured film is more likely to expand in the in-plane direction during the first irradiation step described below, and at the same time, the cured film is more likely to buckle, and therefore wrinkles corresponding to the ridge portions 5B are more likely to appear on the coating film surface. Furthermore, if an acrylate with a high number of repetitions is used, the gloss value tends to decrease and the design properties tend to improve. However, if the number of repetitions is increased, the crosslinking density may decrease, which may reduce the scratch resistance of the surface protective layer. Furthermore, if an acrylate with a low number of repetitions is used, it may be difficult to achieve high processability.
• trifunctional acrylates containing repeating units examples include EO-modified, PO-modified, or CL-modified trimethylolpropane triacrylate, glycerin triacrylate, isocyanurate triacrylate, or pentaerythritol triacrylate.
• the number of repeating units is preferably 9 or more and 15 or less.
• the molecular weight of trifunctional acrylates containing repeating units is, for example, in the range of 690 or more and 1200 or less, and, for another example, in the range of 360 or more and 1135 or less.
• the bifunctional acrylate containing a repeating structure is, for example, polyethylene glycol diacrylate or polypropylene glycol diacrylate, and may contain a caprolactone structure.
• the number of repeating units is preferably 3 or more and 14 or less.
• the molecular weight of the bifunctional acrylate containing a repeating structure is, for example, in the range of 250 or more and 850 or less.
• a pentafunctional or higher acrylate containing a repeating unit is dipentaerythritol polyacrylate.
• the number of repeating units is preferably 12 or less.
• the molecular weight of a pentafunctional or higher acrylate containing a repeating unit is, for example, in the range of 560 to 1200.
• the acrylate may include a tetrafunctional acrylate containing a repeating unit.
• An example of a tetrafunctional acrylate containing a repeating unit is EO-modified, PO-modified, or CL-modified pentaerythritol tetraacrylate.
• the number of repeats of the repeating unit is preferably 20 or more and 25 or less.
• the molecular weight of the tetrafunctional acrylate containing a repeating unit is, for example, in the range of 1,800 or more and 2,000 or less.
• the number of repetitions of the above repeating structure can be analyzed using MALDI-TOF-MS.
• Ionizing radiation curable resins may have a molecular weight distribution. If there is a molecular weight distribution, the above number of repetitions should be the number of repetitions corresponding to the molecular weight with the strongest peak in the MALDI-TOF-MS mass spectrum.
• the particles contained in the surface protection layer 5 can be, for example, particles made of organic materials such as polyethylene (PE) wax, polypropylene (PP) wax, and resin beads, or particles made of inorganic materials such as silica, glass, alumina, titania, zirconia, calcium carbonate, and barium sulfate.
• PES polyethylene
• PP polypropylene
• resin beads or particles made of inorganic materials such as silica, glass, alumina, titania, zirconia, calcium carbonate, and barium sulfate.
• the particles preferably have an average particle size (D50) of 3 ⁇ m or more.
• the average particle size (D50) of the particles is more preferably 3 ⁇ m or more and 11 ⁇ m or less, and even more preferably 3 ⁇ m or more and 8 ⁇ m or less.
• the surface protective layer 5 contains particles, wrinkles can be more uniformly generated on the coating surface in the first irradiation step described below.
• the average particle size (D50) of the particles increases, there is a tendency for the user to feel a stronger sense of particle unevenness. For this reason, if the average particle size (D50) is too large, it can be difficult to achieve a "sanding feel.” Furthermore, if the average particle size (D50) of the particles is large, particles are more likely to fall off from the surface protective layer 5, making it difficult to achieve high scratch resistance. Furthermore, if the particles are small, the effect of generating wrinkles uniformly can be reduced. Furthermore, if the particles are small, it can be difficult to create a sanding feel.
• average particle size (D50) refers to the median size (D50) measured using a laser diffraction/scattering particle size distribution analyzer. If the coating liquid for the surface protective layer contains particles, the surface protective layer 5 obtained from this coating liquid will also contain particles. The average particle size of the particles contained in the surface protective layer 5 can be determined by observing the cross section of the layer and averaging the particle sizes of multiple particles. The value obtained in this manner is essentially the same as the median size (D50) measured using a laser diffraction/scattering particle size distribution analyzer. Therefore, the above-mentioned range of average particle sizes can also be interpreted as the range of average particle sizes of the particles contained in the surface protective layer 5.
• the particles are preferably contained in the surface protection layer 5 in an amount of 5 to 10 parts by weight per 100 parts by weight of resin. It is more preferable that the amount of particles added is 5 to 7 parts by weight per 100 parts by weight of resin. Note that "100 parts by weight of resin” refers to the parts by weight of the solid content of the resin.
• the glossiness of the surface protective layer 5 is preferably less than 10.0, and more preferably 5 or less.
• glossiness is the measured value when measured at an incident angle of 60 degrees using a glossmeter conforming to JIS Z8741:1997.
• the decorative sheet 1 is manufactured, for example, by the following method.
• explanations of the design layer 3, transparent resin layer 4, primer layer 6, adhesive layer 7, and hiding layer 8 are omitted here.
• the coating liquid for the surface protective layer may further contain a solvent and additives to improve the functionality of the final product, such as antibacterial agents and antifungal agents.
• the coating liquid for the surface protective layer may further contain other additives such as ultraviolet absorbers and light stabilizers.
• ultraviolet absorbers examples include benzotriazoles, benzoates, benzophenones, and triazines.
• light stabilizers examples include hindered amines.
• a surface protective layer 5 with low gloss can be formed without the use of gloss adjusters (matt additives).
• the surface protective layer coating liquid further contains a photoinitiator.
• the photoinitiator is not particularly limited, but examples include benzophenone-based, acetophenone-based, benzoin ether-based, and thioxanthone-based photoinitiators.
• a coating film made from a surface protection layer coating liquid is formed on one surface of the raw fabric layer 2.
• This coating film can be formed by various printing methods, such as gravure printing, offset printing, screen printing, electrostatic printing, and inkjet printing, or various coating methods, such as roll coating, knife coating, microgravure coating, and die coating.
• the first irradiation step is carried out.
• the coating film is irradiated with light having a wavelength of 200 nm or less (hereinafter referred to as the first radiation).
• the ionizing radiation curable resin contained in the coating liquid for the surface protective layer has a large absorption coefficient for the first radiation. Therefore, the first radiation incident on the coating film can only reach a position several tens to several hundred nm away from the outermost surface. Therefore, in the first irradiation step, the crosslinking reaction proceeds in the surface region of the coating film, forming an extremely thin cured film, while in other regions the crosslinking reaction does not proceed and the film remains semi-cured.
• the coating film After the first irradiation step, the coating film has wrinkles on its surface that correspond to the ridge portions 5B.
• the first radiation can only reach a position tens to hundreds of nanometers away from the outermost surface of the coating film.
• the crosslinking reaction of the ionizing radiation curable resin caused by irradiation with the first radiation only occurs on the surface of the coating film, and areas more than tens to hundreds of nanometers away from the outermost surface are partially uncured, resulting in the presence of highly fluid molecules.
• These highly fluid molecules swell the cured film, increasing its volume. The increase in volume in the in-plane direction generates in-plane compressive stress, causing the cured film to buckle, resulting in wrinkles on the surface of the coating film.
• the first radiation can be extracted from excimer VUV (Vacuum Ultra Violet) light.
• Excimer VUV light can be produced from lamps that use rare gases or rare gas halide compounds. When high-energy electrons are supplied from the outside to a lamp filled with rare gases or rare gas halide compounds, a large number of discharge plasmas (dielectric barrier discharges) are generated. This plasma discharge excites the atoms of the discharge gas (rare gas), which momentarily enter an excimer state. When returning from this excimer state to the ground state, light is emitted in a wavelength range specific to that excimer.
• the gas used in excimer lamps can be any conventional gas that emits light of 200 nm or less.
• gases that can be used include rare gases such as Xe, Ar, and Kr, and mixed gases of rare gases such as ArBr and ArF with halogen gas.
• Excimer lamps have different wavelengths (center wavelengths) depending on the gas used, such as approximately 172 nm (Xe), approximately 126 nm (Ar), approximately 146 nm (Kr), approximately 165 nm (ArBr), and approximately 193 nm (ArF).
• a xenon lamp that emits excimer light with a central wavelength of 172 nm as the light source. Also, considering the cost of maintaining the equipment and the availability of materials, it is preferable to use a xenon lamp as the light source.
• the first irradiation step is carried out in an atmosphere with a low oxygen concentration.
• Oxygen has a high absorption coefficient for light of 200 nm or less. Therefore, the first irradiation step is preferably carried out in, for example, a nitrogen gas atmosphere.
• the oxygen concentration in the gas phase during the first irradiation step i.e., the residual oxygen concentration in the reaction atmosphere, is preferably 100 ppm or less, and more preferably 20 ppm or less.
• oxygen in the atmosphere inhibits radical polymerization. Therefore, the residual oxygen concentration in the reaction atmosphere affects the formation of wrinkles on the coating surface. Therefore, changing the residual oxygen concentration in the reaction atmosphere can also change the surface properties of the surface protective layer 5.
• the cumulative light amount of the first radiation is preferably 8 mJ/cm 2 or more and 20 mJ/cm 2 or less, and more preferably 10 mJ/cm 2 or more and 17 mJ/cm 2 or less.
• the cumulative light amount is reduced, it is easier to obtain a surface protection layer 5 having the above-described surface texture.
• the first irradiation step is preferably carried out within a temperature range of 20°C or higher and 65°C or lower. If the temperature in the first irradiation step is within the above range, it is easier to obtain a surface protection layer 5 having the above-mentioned surface properties.
• the second irradiation step is carried out.
• the coating film is irradiated with a second radiation to harden the entire coating film. This results in the surface protection layer 5.
• the second radiation is ionizing radiation such as an electron beam, or ultraviolet radiation with a longer wavelength than the first radiation.
• the cumulative light amount of the second radiation is preferably 10 mJ/cm 2 or more and 500 mJ/cm 2 or less, more preferably 50 mJ/cm 2 or more and 400 mJ/cm 2 or less, and even more preferably 100 mJ/cm 2 or more and 300 mJ/cm 2 or less.
• the decorative sheet 1 can be manufactured, for example, by the method described above.
• the decorative sheet 1 may also be manufactured by other methods.
• a plate may be formed using the method described above for the surface protective layer 5, and the surface protective layer 5 having a relief structure on its surface may be formed by transfer using this plate.
• the decorative sheet 1 described with reference to Figures 1 to 3 has the surface protective layer 5 with the above-mentioned surface properties.
• Such a decorative sheet 1 can provide a unique tactile sensation to the user. For example, when a user presses the surface of the surface protective layer 5 with their finger and then slides their finger over the surface of the decorative sheet 1 described above, the user is given a smooth, yet uneven, textured sensation that differs from a completely smooth surface, i.e., a "sanding sensation.” This tactile sensation will be explained below.
• the autocorrelation length Sal of the uneven structure of the surface protective layer 5 is within the above-mentioned range. Therefore, the uneven structure has a small pitch. As a result, when a user presses their finger against the surface of the surface protective layer 5 and then slides their finger across the surface, the user is given a smooth feel.
• the decorative sheet 1 described above has a root-mean-square gradient Sdq of the uneven structure that falls within the above-mentioned range. Furthermore, the decorative sheet 1 described above has a convex area ratio that falls within the above-mentioned range. The convex portions that form this uneven structure are appropriately steep, and their peaks are appropriately small. Therefore, when a user runs their finger over the surface of the surface protection layer 5, the decorative sheet 1 stimulates the user's finger, giving the user a sense of unevenness.
• the decorative sheet 1 when the autocorrelation length Sal of the uneven structure is within the above-mentioned range, the decorative sheet 1 provides a smooth feel to the user, and when the root-mean-square gradient Sdq and convex area ratio of the uneven structure are within the above-mentioned range, the decorative sheet 1 provides a sense of unevenness to the user. Therefore, while the decorative sheet 1 is smooth, it provides the user with a sense of unevenness that is different from a completely smooth surface, i.e., a "sanding feel.”
• a decorative sheet that gives a sanded look preferably has low gloss. However, if an attempt is made to achieve low gloss by providing a textured structure on the decorative sheet to make specular reflection less likely, diffuse reflection becomes more likely to occur, and the surface protective layer 5 may appear cloudy.
• the decorative sheet 1 described above has the surface properties described above, diffuse reflection and glare are less likely to occur in the surface protective layer 5. This is explained below.
• the autocorrelation length Sal of the uneven structure is within the range described above.
• the root-mean-square gradient Sdq of the uneven structure is within the range described above.
• Such an uneven structure has a relatively large number of convex portions, and the slopes of the convex portions are moderately steep, so light that is incident on the convex portions easily penetrates into the surface protective layer 5. Therefore, diffuse reflection and specular reflection are unlikely to occur in the surface protective layer 5. Therefore, clouding of the surface protective layer 5 due to diffuse reflection is unlikely to occur. Furthermore, because specular reflection is unlikely to occur, glare is also unlikely to occur.
• the surface protective layer 5 of the decorative sheet 1 has the surface properties described above, and therefore can achieve a low gloss level even without containing a gloss adjuster (matt additive).
• Gloss adjusters reduce the oil repellency of layers formed from resin materials, making surface protective layers 5 containing gloss adjusters more susceptible to fingerprints.
• Surface protective layers 5 that do not contain gloss adjusters are less likely to absorb oil and therefore less likely to be marked with fingerprints.
• surface protective layers 5 with excellent oil repellency are less likely to develop oil stains or adsorb contaminants.
• gloss adjuster particles do not fall off, and therefore decorative sheets 1 containing such surface protective layers 5 are less likely to develop gloss changes or scratches.
• the surface protection layer 5 can achieve a low gloss level. In this case, it is possible to reduce the reflection of external light on the surface of the surface protection layer 5.
• Oxygen in the gas phase during the first irradiation step not only absorbs short-wavelength ultraviolet light, but also inhibits radical polymerization.
• the effect of oxygen contained in the gas phase on radical polymerization is greatest in the portions of the coating film made of ionizing radiation-curable resin that are adjacent to the gas phase, and decreases as the distance from the coating film surface increases. Therefore, by changing the oxygen concentration in the gas phase during the first irradiation step, it is possible to change the relationship between the distance from the coating film surface and the progress of the crosslinking reaction.
• the thickness of the cured film formed on the surface of the coating by the first irradiation process and the degree of in-plane expansion of the cured film as the crosslinking reaction progresses will change.
• the thickness of the cured film and the degree of in-plane expansion of the cured film are also affected by the integrated light dose in the first irradiation process.
• the thickness of the cured film and the degree of in-plane expansion of the cured film also affect the surface properties of the surface protection layer.
• the amount of particles added to the coating and the thickness of the coating also affect the formation of wrinkles.
• Example 1 The decorative sheet 1 described with reference to Figures 1 to 3 was produced by the following method: In this example, the transparent resin layer 4, primer layer 6, adhesive layer 7, and masking layer 8 were omitted.
• an impregnated paper (GFR-506, manufactured by Kohjin Co., Ltd.) with a basis weight of 50 g/ m2 was prepared as the raw fabric layer 2.
• a design layer 3 was formed using an oil-based nitrocellulose resin gravure printing ink (PCNT (PCRNT) various colors, manufactured by Toyo Ink Co., Ltd.).
• PCNT nitrocellulose resin gravure printing ink
• the design pattern of the design layer was a wood grain pattern.
• a coating liquid for a surface protective layer was prepared by blending the following ionizing radiation curable resins A and B with the following particles.
• ⁇ Ionizing radiation curable resin A Type Trimethylolpropane EO-modified triacrylate (EO 15 moles added)
• Blend 97 parts by mass / ionizing radiation curable resin
• B Type Dipentaerythritol polyacrylate
• A-DPH manufactured by Shin-Nakamura Chemical Co., Ltd.
• Formulation 3 parts by mass of particles
• Product name: SYLYSIA320 manufactured by Fuji Silysia Chemical Ltd.
• Particle size 3.2 ⁇ m Blend: 5 parts by mass.
• the coating liquid for the surface protective layer was stirred as follows. First, the coating liquid for the surface protective layer was placed in a stirring vessel. A ZT-20 (manufactured by Satake Multinics Co., Ltd.) was used as the stirring vessel. A Satake Multi A Mixer AT14-VPR-0.09BI (manufactured by Satake Multinics Co., Ltd.) was used for stirring. The stirring method was centripetal stirring. The power for stirring the coating liquid for the surface protective layer was 0.75 kW, and the stirring time was 5 minutes.
• a surface protective layer coating liquid was applied onto the design layer 3.
• a coating film made from the surface protective layer coating liquid was formed to a thickness of 4.0 ⁇ m.
• a first irradiation step was carried out. Specifically, at 25°C, under atmospheric pressure, and in a nitrogen gas atmosphere with an oxygen concentration of 33.2 ppm, the surface of the coating film made of the coating liquid for surface protective layer was irradiated with ultraviolet light having a wavelength of 172 nm using a Xe excimer lamp with an illuminance of 6 mW/cm2 so that the cumulative light amount was 12 mJ/ cm2 . This caused wrinkles to form on the surface of the coating film.
• the second irradiation step was carried out. Specifically, the coating film was irradiated with ionizing radiation to cure the entire coating film, thereby forming the surface protective layer 5. In this manner, a decorative sheet 1 was obtained.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the oxygen concentration in the first irradiation step was set to 36.6 ppm. Then, a coating film made of the surface protective layer coating liquid was formed to a thickness of 7.2 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the oxygen concentration in the first irradiation step was set to 31.2 ppm. Then, a coating film made of the surface protective layer coating liquid was formed to a thickness of 9.1 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points:
• the following ionizing radiation curable resin was used.
• the oxygen concentration in the first irradiation step was set to 35.1 ppm.
• a coating film made of the coating liquid for surface protection layer was formed to a thickness of 6.8 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points:
• the following ionizing radiation curable resins A and B were used.
• ⁇ Ionizing radiation curable resin A Type Polyethylene glycol diacrylate Product name: A-1000 (manufactured by Shin-Nakamura Chemical Co., Ltd.) Blend: 60 parts by mass / ionizing radiation curable resin B Type: Trimethylolpropane EO-modified triacrylate (EO 15 moles added)
• the oxygen concentration in the first irradiation step was set to 30.5 ppm, and the temperature was set to 65° C.
• a coating film made of the coating liquid for surface protection layer was formed to a thickness of 2.9 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points:
• the following ionizing radiation curable resins A and B were used.
• ⁇ Ionizing radiation curable resin A Type Tricyclodecane dimethanol diacrylate
• Blend 60 parts by mass / ionizing radiation curable resin
• B Type Trimethylolpropane EO-modified triacrylate (EO 15 moles added)
• the oxygen concentration in the first irradiation step was set to 32.5 ppm.
• a coating film made of the coating liquid for surface protective layer was formed to a thickness of 4.4 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points:
• the following ionizing radiation curable resins A and B were used.
• ⁇ Ionizing radiation curable resin A Type Tricyclodecane dimethanol diacrylate
• Blend 60 parts by mass / ionizing radiation curable resin
• B Type Trimethylolpropane EO-modified triacrylate (EO 15 moles added)
• the oxygen concentration in the first irradiation step was set to 36.6 ppm, and the temperature was set to 65° C.
• a coating film made of the coating liquid for surface protective layer was formed to a thickness of 7.4 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. Specifically, in this example, the particle blending amount was 10 parts by mass. The oxygen concentration in the first irradiation step was 31.6 ppm. A coating film made of the surface protective layer coating liquid was formed to a thickness of 4.9 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, particles were not blended.
• the oxygen concentration in the first irradiation step was set to 33.9 ppm.
• a coating film made of the surface protective layer coating liquid was then formed to a thickness of 7.2 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, particles were not blended.
• the oxygen concentration in the first irradiation step was set to 31.7 ppm.
• a coating film made of the surface protective layer coating liquid was then formed to a thickness of 12.2 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the oxygen concentration in the first irradiation step was set to 31.4 ppm. Then, a coating film made of the surface protective layer coating liquid was formed to a thickness of 1.5 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points:
• the following ionizing radiation curable resins A and B were used.
• ⁇ Ionizing radiation curable resin A Type Dipentaerythritol polyacrylate
• Blend 60 parts by mass / ionizing radiation curable resin
• B Type Trimethylolpropane EO-modified triacrylate (EO 15 moles added)
• the oxygen concentration in the first irradiation step was set to 32.0 ppm.
• a coating film made of the coating liquid for surface protection layer was formed to a thickness of 3.5 ⁇ m.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, a coating film made of a surface protective layer coating liquid was formed to a thickness of 4.0 ⁇ m, and then the coating film was cured only by the second irradiation step without performing the first irradiation step. The oxygen concentration in the second irradiation step was set to 37.1 ppm.
• Decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. Specifically, in this example, the particle blending amount was 15 parts by mass. The oxygen concentration in the first irradiation step was 32.9 ppm. A coating film made of the surface protective layer coating liquid was formed to a thickness of 2.7 ⁇ m.
• a decorative sheet 1 was produced in the same manner as in Example 1, except for the following points. That is, in this example, the oxygen concentration in the first irradiation step was set to 35.3 ppm. Then, a coating film made of the surface protective layer coating liquid was formed to a thickness of 11.0 ⁇ m.
• the thickness of the surface protective layer 5 was measured as follows. First, Pt is sputtered (40 mA, 20 seconds) on the surface of the surface protection layer 5 to form a Pt film for use as an interface mark. Next, the sample with the Pt film formed thereon is embedded in a photocurable resin, and then a cross section parallel to the thickness direction of the surface protection layer 5 is exposed. To expose the cross section, for example, an ultramicrotome (Leica Microsystems, EM UC7) is used. Then, this cross section is observed at 1000x magnification with an optical microscope. For example, an optical microscope (BX53M) manufactured by Olympus Corporation is used for this observation.
• an optical microscope BX53M manufactured by Olympus Corporation is used for this observation.
• the shape of the surface protection layer 5 is extracted from this cross-sectional image using the method described below.
• ImageJ is used as the image processing software for shape extraction. Specifically, the connected cross-sectional image is first converted into an 8-bit grayscale image. Next, in order to later set the gradation value of only the area corresponding to the surface protection layer to 255, the Subtract function of ImageJ is used to subtract 1 from the gradation values of all pixels. This adjusts the maximum gradation value to 254. Next, for the image with adjusted gradation values, the Polygon selection function of ImageJ is used to polygonally approximate the outline of the area corresponding to the surface protection layer. The outline of the polygonal approximation area is further converted into a smooth shape using the Fit Spline function of ImageJ.
• the binary image is converted into a 32-bit grayscale image.
• the gradation values of pixels corresponding to the above-mentioned bright areas remain at 255, and the gradation values of pixels corresponding to the above-mentioned dark areas remain at zero.
• the gradation value of each pixel is multiplied by the vertical dimension H ( ⁇ m) of the above-mentioned field of view, which corresponds to the total vertical length of the image.
• H ( ⁇ m) the vertical dimension of the above-mentioned field of view
• this product is divided by 255.
• the gradation values of pixels corresponding to the above-mentioned dark areas remain at zero, and the gradation values of pixels corresponding to the above-mentioned bright areas are replaced with the above dimension H ( ⁇ m).
• the gradation values of the pixels lined up vertically are added up for each horizontal coordinate (pixel) of the image, and a value is extracted by dividing this value by the number of pixels N in the vertical direction of the image.
• the gradation values of the pixels included in the area corresponding to the surface protection layer in the image are replaced by the vertical dimension H of the field of view, which corresponds to the entire vertical length of the image, and therefore the value obtained by dividing this added value by the number of pixels N in the vertical direction of the image can be taken as the film thickness of the surface protection layer for a specific horizontal coordinate.
• each of the above evaluators was asked, while blindfolded, to press the surface of the surface protective layer with their finger and slide their finger across the surface, and then to classify the tactile sensation related to surface roughness into one of the three groups mentioned above. This procedure was then repeated until the evaluations by each evaluator were consistent three or more times in a row, and the evaluation results between evaluators were consistent three times in a row. Based on these results, the tactile sensation was evaluated according to the above criteria.
• each of the above evaluators was asked to observe each of the decorative sheets produced in the above examples and comparative examples, and then to classify the degree of cloudiness into the three groups mentioned above. This procedure was then repeated until the evaluations by each evaluator were consistent three or more times in a row, and the evaluation results between the evaluators were consistent three or more times in a row. From these results, the degree of cloudiness was evaluated according to the above criteria.
• the decorative sheet When observing the decorative sheet, if the diffuse reflection from the surface protective layer 5 appears stronger than the light reflected from the pattern layer, the decorative sheet will appear cloudy.
• Stain Resistance To evaluate stain resistance, the Stain A test specified in the Japanese Agricultural Standards (JAS) was carried out. That is, 10 mm wide lines were drawn on the surface protective layer of each decorative sheet using blue ink, black quick-drying ink, and red crayon, and the sheets were left for 4 hours. Thereafter, the blue ink, black quick-drying ink, and red crayon lines were wiped off with a cloth soaked in ethanol.
• JS Japanese Agricultural Standards
• A No reflection occurred on the surface of the decorative sheet.
• B There was some glare on the surface of the decorative sheet.
• C Significant reflection occurred on the surface of the decorative sheet.
• each of the evaluators was asked to observe each of the decorative sheets produced in the above examples and comparative examples, and then to classify the degree of reflection into the three groups described above. This procedure was repeated until the evaluations by each evaluator were consistent three or more times in a row, and the evaluation results between the evaluators were consistent three or more times in a row. From these results, the degree of reflection was evaluated according to the above criteria.
• a weather resistance test was conducted on each of the decorative sheets produced in the above examples and comparative examples using a xenon weather meter (manufactured by Suga Test Instruments, product name: X75) under the following conditions: illuminance 60 W/ m2 , wavelength 300-400 nm, chamber environment 44.3°C/50% RH, exposure time 240 hours.
• the appearance (i.e., gloss, etc.) of the decorative sheet after the weather resistance test was visually compared with the appearance of a decorative sheet that had not been subjected to the weather resistance test.
• the appearance of the decorative sheet after the weather resistance test was then evaluated based on the following criteria.
• the image processing procedure included performing "Waviness Removal: Strength 5" in the "Surface Shape Correction" of the image processing tool, followed by "Height Cut Level: Strong,” then performing “Height Cut Level: Strong” again, then performing "Noise Removal: Strong,” and finally performing "Noise Removal: Strong” again.
• the decorative sheets of Examples 1 to 10 gave the evaluators a sanding sensation. Furthermore, these decorative sheets either developed slight cloudiness or no clouding. Furthermore, these decorative sheets either developed slight reflection or no reflection. In particular, the decorative sheets of Examples 2 and 7 developed neither cloudiness nor reflection, gave the evaluators a sanding sensation, and were also excellent in stain resistance and weather resistance. On the other hand, the decorative sheets of Comparative Examples 1 to 5 did not give the evaluators a sanding sensation. Furthermore, the decorative sheet of Comparative Example 3 had a high gloss due to its strong specular reflection. While this decorative sheet produced strong specular reflection, it was not prone to diffuse reflection, so the decorative sheet did not appear cloudy.

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