JP7501005B2 - Decorative sheet - Google Patents

Description

The present invention relates to a decorative sheet used for the surface decoration of the interior and exterior of buildings, fittings, furniture, construction materials, flooring materials, etc.

In recent years, as shown in Patent Document 1, many decorative sheets using olefin resins (e.g., polypropylene sheets) have been proposed as alternatives to decorative sheets made of polyvinyl chloride, which are of concern in terms of environmental protection. These decorative sheets do not use vinyl chloride resin, and therefore the generation of toxic gases and the like during incineration is suppressed. When a resin with high crystallinity and high isotacticity is used to improve the scratch resistance of soft polyolefin sheets made of olefin resins used as decorative sheets, there is a problem that the decorative sheets have poor weather resistance. In response to this, Patent Document 2 discloses providing a surface protective layer made of a resin containing a triazine-based organic ultraviolet absorber on the surface of the polyolefin sheet.

Furthermore, titanium oxide, a typical inorganic pigment, exhibits strong oxidizing power when excited by light. When decorative materials containing titanium oxide are used for exterior applications, the photocatalytic action of titanium oxide may cause decomposition or chemical reactions of the resin contained in the base material, resulting in deterioration of the resin and layer peeling, reducing weather resistance.
In response to this, focusing on the fact that light that excites the photocatalytic action of titanium oxide includes ultraviolet light in the wavelength range of 380 nm or less, a method is known in which an ultraviolet absorbing agent is added to the surface protective layer of a decorative sheet that is exposed to light to suppress the photocatalytic action of titanium oxide caused by ultraviolet light.

By the way, a decorative sheet is attached to the surface of a substrate such as a wooden substrate, a metal substrate, or a non-flammable substrate to become a decorative board, and the decorative sheet imparts a design to the decorative board according to the purpose. Therefore, the decorative sheet needs to cover the surface of the substrate completely as necessary. In this case, it is necessary to use a decorative sheet that is at least colored with a pigment and has concealing properties. The simplest configuration of a decorative sheet is a configuration with only a base layer consisting of a single colored sheet (single layer). In the case of such a decorative sheet consisting of only a base layer, the design that can be imparted is usually limited to a single color without a pattern, but it is possible to impart a sense of brilliance by adding a lustrous material such as aluminum flakes or pearl pigments as a pigment, so that a necessary and sufficient design expression is possible. In addition, if you want to impart a more sophisticated design, it is also effective to decorate the surface of the base layer by printing, etc.

Among decorative sheets, white sheets are used for door frames, baseboards, various storage compartments, etc. The surface of the base material is easily visible through the white sheet, and a large amount of pigment needs to be added to impart hiding power. However, adding a large amount of pigment causes a problem of poor weather resistance of the white sheet. Patent Document 3 proposes a decorative sheet that contains an inorganic pigment in a vesiculated state, and has excellent hiding power even when the amount of pigment added is increased, but it is not possible to avoid increasing the amount of pigment added, and the problem of poor weather resistance has not been solved.

Patent No. 3271022 Patent No. 4032829 JP 2016-155233 A

First, even if the weather resistance of only the surface protective layer located at the top of the decorative sheet is improved, there is a problem that, for example, sufficient weather resistance is not obtained in the cracks present in the surface protective layer, and the pattern layer or base layer located in the lower layers may deteriorate and whiten. In addition, in the case of a decorative sheet that does not have a surface protective layer and has an embossed pattern formed on the surface of the transparent resin layer that is the top layer, no matter how much the weather resistance of the transparent resin layer is improved, there is a risk that sufficient weather resistance will not be obtained in the recesses of the embossed pattern where the layer thickness is thin. For this reason, there was a problem that deterioration may progress from the parts located in the recesses in the pattern layer or base layer provided in the lower layer, causing whitening or breakage.

In addition, in order to achieve high hiding power, it is necessary to increase the concentration of inorganic pigments, which makes it difficult to improve weather resistance. Furthermore, when a large amount of ultraviolet absorber is contained in the base layer in order to improve weather resistance, the aggregated ultraviolet absorber bleeds out on the surface of the resin composition, causing powdery lifting on the surface of the base layer and a decrease in interlayer adhesion.
An object of the present invention is to provide a decorative sheet that combines weather resistance, hiding power, and bleed-out resistance.

The inventors conducted extensive research and experimentation into the optimum UV absorber and the amount of UV absorber added to a substrate layer containing an inorganic pigment and a polyolefin resin, and discovered that it is possible to provide a decorative sheet that overcomes the above-mentioned problems.

In order to achieve the object, a decorative sheet according to one embodiment of the present invention is a base layer containing an inorganic pigment and a polyolefin resin, the base layer containing a triazine-based ultraviolet absorber, the triazine-based ultraviolet absorber containing a first hydroxyphenyltriazine-based ultraviolet absorber (UVA-A) having a structure represented by the following general formula (1) and a second hydroxyphenyltriazine-based ultraviolet absorber (UVA-B) having a structure represented by the following general formula (2), the content of each of the first hydroxyphenyltriazine-based ultraviolet absorber (UVA-A) and the second hydroxyphenyltriazine-based ultraviolet absorber (UVA-B) being in the range of 10/90 to 90/10 in terms of the mass ratio (UVA-A/UVA-B) of the first hydroxyphenyltriazine-based ultraviolet absorber (UVA-A) to the second hydroxyphenyltriazine-based ultraviolet absorber (UVA-B), and the average absorbance in the wavelength range of 450 nm to 800 nm is 1.0 to 2.0.

（一般式（１）中、Ｒ１からＲ３はそれぞれ独立し、水素原子またはメチル基またはフェニル基またはアルコキシ基を示し、かつ少なくとも２つが炭素数６から１８のアルコキシ基であり、Ｒ４、Ｒ５はそれぞれ独立し、ヒドロキシル基またはメチル基または水素原子を示し、Ｒ６からＲ８はそれぞれ独立し、メチル基または水素原子を示す。）

(In general formula (1), R1 to R3 each independently represent a hydrogen atom, a methyl group, a phenyl group, or an alkoxy group, and at least two of them are an alkoxy group having 6 to 18 carbon atoms; R4 and R5 each independently represent a hydroxyl group, a methyl group, or a hydrogen atom; and R6 to R8 each independently represent a methyl group or a hydrogen atom.)

（一般式（２）中、Ｒ１は炭素数８から１８のアルコキシ基であり、Ｒ２からＲ５はそれぞれ独立し、水素原子またはメチル基を示す。）

(In general formula (2), R1 is an alkoxy group having 8 to 18 carbon atoms, and R2 to R5 are each independently a hydrogen atom or a methyl group.)

According to one aspect of the present invention, by adding an optimal amount of an optimal UV absorber to a substrate layer containing an inorganic pigment and a polyolefin resin, a decorative sheet with weather resistance, hiding power, and bleed-out resistance can be provided.

1 is a cross-sectional view showing a configuration of a decorative sheet according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of another decorative sheet according to an embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, and the like differ from the actual ones. The embodiments shown below are illustrative of configurations for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the materials, shapes, structures, and the like of the components as described below. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.

"composition"
The decorative sheet 10 of the embodiment shown in FIG. 1 is an example of the case where a base layer 1 alone is used. As shown in FIG. 1, the base layer 1 of this embodiment may be composed of a colored layer 2 formed by mixing an inorganic pigment with a polypropylene resin, and a skin layer 3 formed on at least one side of the colored layer 2 and made of polypropylene resin. The skin layer 3 is intended to prevent the inorganic pigment contained in the colored layer 2 from bleeding and adhering to the manufacturing equipment during the manufacturing process, resulting in poor film formation. The skin layer 3 may contain a nano-sized nucleating agent to improve the crystallinity. By improving the crystallinity, the scratch resistance is improved. In this embodiment, the nucleating agent may be contained in the form of a nucleating agent vesicle that is vesiculated by being enclosed in an outer membrane.

As shown in FIG. 2, a pattern layer 4 may be formed (laminated) on one side of the base layer 1 as necessary to improve the design. The decorative sheet 10 may also have at least one of a transparent resin layer 5 and a topcoat layer 6 laminated on one side of the base layer 1. The decorative sheet 10 illustrated in FIG. 2 is an example in which a pattern layer 4, a dry lamination adhesive layer 7, a transparent resin layer 5, and a topcoat layer 6 are laminated in this order on one side of the decorative sheet 10. Either the transparent resin layer 5 or the topcoat layer 6 may be omitted. The pattern layer 4 may also be omitted.

However, when the decorative sheet 10 of this embodiment is provided with the transparent resin layer 5 and the surface protection layer 6, it is preferable to design the total thickness to be within the range of 100 μm or more and 250 μm or less. If the total thickness of the decorative sheet 10 is less than 100 μm, the strength of the decorative sheet 10 as a whole will be insufficient, and problems may arise with smoothness during wrapping processing. If the total thickness of the decorative sheet 10 exceeds 250 μm, the strength of the decorative sheet 10 as a whole will be too high, and problems may arise during bending processing.

When the transparent resin layer 5 and the top coat layer 6 are provided, the film thickness may be, for example, 140 μm for the base layer 1, 95 μm for the transparent resin layer 5, and 15 μm for the top coat layer 6. Here, among the base layer 1, the pattern layer 4, the transparent resin layer 5, and the top coat layer 6, the pattern layer 4 has a thin layer thickness, so the total thickness of the entire decorative sheet 10 may be designed to be in the range of 100 μm to 250 μm, ignoring the thickness of the pattern layer 4. Here, at least one of the transparent resin layer 5 and the top coat layer 6 may be given an uneven shape by embossing depending on the design requirements. Furthermore, it is possible to laminate at least one of the transparent resin layer 5 and the top coat layer 6 in multiple layers due to requirements such as scratch resistance, and other known layers may be arranged.

1 and 2, the symbol B represents a substrate. The substrate B is a substrate to which the decorative sheet 10 is attached. The substrate B is not particularly limited, but examples thereof include wood boards, inorganic boards, metal plates, and composite boards made of multiple materials. In addition, a primer layer or a concealing layer may be provided between the decorative sheet 10 and the substrate B as appropriate. The tensile modulus of the decorative sheet 10 of this embodiment, particularly the tensile modulus of the base material layer 1 alone, is preferably in the range of 700 MPa to 2000 MPa. If the tensile modulus is less than 700 MPa, defects during printing processing cannot be suppressed, or surface smoothness during wrapping processing may not be maintained. If the tensile modulus exceeds 2000 MPa, the crystallinity is too high, so even if a nucleating agent vesicle is used, defects such as whitening and cracking may occur during bending processing. The preferred range of the tensile modulus is 1000 MPa to 1800 MPa. By keeping the value within this range, it is possible to achieve excellent results in terms of defects during printing, scratch resistance, surface smoothness during wrapping, tearability, and bending.

Next, each layer constituting the decorative sheet 10 will be described.
<Base layer 1>
The base layer 1 is made of polyolefin resin as a main raw material, and is colored by mixing inorganic pigment into the polyolefin resin. When the skin layer 3 is provided, it is formed containing polyolefin resin and does not contain inorganic pigment.
Furthermore, when a nano-sized nucleating agent is added for the purpose of increasing the crystallinity of the base layer 1, it is desirable to add it to the skin layer 3 if a skin layer 3 is provided.

The base layer 1 contains hydroxyphenyltriazine-based ultraviolet absorbents having structures represented by the following general formulas (1) and (2), i.e., a first hydroxyphenyltriazine-based ultraviolet absorbent UVA-A and a second hydroxyphenyltriazine-based ultraviolet absorbent UVA-B, such that the mass ratio of UVA-A to UVA-B (UVA-A/UVA-B) is within the range of 10/90 to 90/10.
In protecting the film in the decorative sheet 10 according to this embodiment, if the mass ratio of UVA-A to UVA-B (UVA-A/UVA-B) is less than 10/90, the content of UVA-A is too low, and discoloration of the base layer 1 and the pattern layer 4 described below may be significant. Also, if the mass ratio of UVA-A to UVA-B (UVA-A/UVA-B) exceeds 90/10, the content of UVA-A is too high, and absorption on the short wavelength side becomes weak, and whitening or cracking of the protective film 10 itself may occur easily. Thus, in either case, problems with weather resistance may occur.

As UVA-A, a compound represented by the following general formula (3) is preferable, and in particular, a compound represented by the following formula (4), 2,4-bis[2-hydroxy-4-(2-ethylhexyloxy)phenyl]-6-(4-methoxyphenyl)-s-triazine, is more preferable.
Examples of UVA-B include compounds represented by the following formulas (5), (6), and (7), and in particular, the compound represented by the following formula (5), 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(octyloxy)phenyl]-s-triazine, is preferred. The octyloxy group in this compound may be either linear or branched.

In general formula (1), R1 to R3 are each independently a hydrogen atom, a methyl group, a phenyl group, or an alkoxy group, and at least two of them are alkoxy groups having 8 to 18 carbon atoms; R4 and R5 are each independently a hydroxyl group, a methyl group, or a hydrogen atom; and R6 to R8 are each independently a methyl group or a hydrogen atom.

In the general formula (2), R1 is an alkoxy group having 8 to 18 carbon atoms, and R2 to R5 are
each independently represents a hydrogen atom or a methyl group.

In general formula (3), R1 and R2 are alkoxy groups having 8 to 18 carbon atoms, R3 is an alkoxy group having 1 to 4 carbon atoms, R4 is a hydroxyl group, and R5 to R8 are hydrogen atoms.

The amount of hydroxyphenyltriazine-based ultraviolet absorbers, i.e., UVA-A and UVA-B, is not particularly limited and is set appropriately depending on various conditions such as the thickness of the base layer 1, but is usually within the range of 0.1 to 2 parts by mass per 100 parts by mass of olefin resin. If the amount of hydroxyphenyltriazine-based ultraviolet absorbers is less than 0.1 parts by mass, it may not be possible to impart sufficient weather resistance to the transparent polyolefin resin layer. Furthermore, if the amount of hydroxyphenyltriazine-based ultraviolet absorbers exceeds 2 parts by mass, powder or liquid may precipitate from the base layer 1, causing problems with the design of the sheet.

The base layer 1 preferably has an average absorbance in the wavelength range of 450 nm to 800 nm in the range of 1.0 to 2.0. If the average absorbance in the wavelength range of 450 nm to 800 nm is less than 1.0, the sheet may not be able to hide the base and may show through. If the absorbance in the wavelength range of 450 nm to 800 nm in excess of 2.0, the pigment concentration will be too high and weather resistance will decrease. The absorbance in the wavelength range of 450 nm to 800 nm inclusive is preferably 1.0 to 2.0, more preferably 1.4 to 1.8.

The product of the thickness C μm of the substrate layer 1 and the inorganic pigment content D mass % divided by 100, [C×D/100], is preferably 0.5 or more, more preferably 2.0 or more, and even more preferably 5.0 or more. The value of [C×D/100] is preferably 100.0 or less, more preferably 60.0 or less, and even more preferably 40.0 or less. With regard to the inorganic pigment concentration in the substrate, if the value of [C×D/100] is within the above range, it is suitable for the decorative sheet to exhibit excellent weather resistance.

(Polyolefin resin)
Examples of the polyolefin resin used in the base layer 1 include polypropylene, polyethylene, polybutene, and the like, as well as α-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-pentene, 4-ethyl ... Examples of the copolymer include a homopolymer or a copolymer of two or more types of α-olefins (e.g., hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc.) and a copolymer of ethylene or an α-olefin with another monomer, such as an ethylene-vinyl acetate copolymer, an ethylene-vinyl alcohol copolymer, an ethylene-methyl methacrylate copolymer, an ethylene-ethyl methacrylate copolymer, an ethylene-butyl methacrylate copolymer, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, or an ethylene-butyl acrylate copolymer.

The polyolefin resin used in the core layer 2 in the base material layer 1 is preferably a highly flexible random polypropylene resin having an ethylene content, or a mixture of a known amorphous polypropylene resin with a random polypropylene resin or a homopolypropylene resin with high crystallinity, taking into consideration the dispersibility of the inorganic pigment. In applications where processability such as bending is more important, for example, a random polypropylene resin having an ethylene content within a specified range or a known amorphous polypropylene resin can be mixed with a highly crystalline homopolypropylene.

In addition, when a skin layer 3 is provided, the polyolefin resin used for the skin layer 3 is preferably a highly flexible random polypropylene resin having an ethylene content, or a mixture of a known amorphous polypropylene resin with a random polypropylene resin or a homopolypropylene resin with high crystallinity.
It is also important that the thickness of the base layer 1 made of a colored polyolefin film is within the range of 40 μm or more and 200 μm or less.

If the thickness of the base layer 1 is less than 40 μm, the film strength is insufficient, making it difficult to suppress defects during printing and deterioration of scratch resistance, and also difficult to maintain surface smoothness during wrapping. On the other hand, if the thickness of the base layer 1 is more than 200 μm, there is a high possibility that defects such as whitening and cracking will occur during bending, and during wrapping, the ability to conform to the edge surface and laminated parts of the wood substrate will be significantly deteriorated, and the adhesive strength will be insufficient, which may cause defects such as peeling over time.
A more preferable range of the thickness of the base layer 1 is 60 μm or more and 150 μm or less. Within this range, defects during printing processing, surface smoothness during wrapping processing, scratch resistance, and bending processing can be achieved with a sufficient margin.

(Inorganic pigments)
The inorganic pigment may be a known inorganic pigment, typically titanium oxide, for imparting hiding power. Examples of inorganic pigments for coloring include iron-zinc, chromium-antimony, iron-aluminum composite oxides, and iron oxide, and the like, and the blending ratio of these can be freely adjusted according to the desired color. In addition, lustrous materials such as aluminum flakes and pearl pigments may also be added as inorganic pigments. Organic pigments such as carbon black may also be used in combination.
Furthermore, additives such as fatty acid metal salts may be added to improve dispersibility and extrusion suitability.

<Pattern layer 4>
A pattern layer 4 can be provided on the surface of the colored polyolefin film (substrate layer 1) to impart a pattern to the decorative sheet 10. Examples of the pattern that can be used include wood grain, stone grain, sand grain, tiled pattern, brickwork pattern, fabric pattern, leather pattern, and geometric figures.
Furthermore, a base solid ink layer (not shown) may be provided between the base layer 1 and the pattern layer 4 depending on the level of the desired design. The base solid ink layer is provided so as to cover the entire surface of the base layer 1. The base solid ink layer may be multi-layered, having two or more layers, as necessary for hiding properties, etc. Furthermore, the pattern layer 2 may be formed by laminating as many plates as necessary to express the desired design. In this way, the pattern layer 2 and the base solid ink layer may be combined in various ways depending on the desired design, that is, the design to be expressed, but are not particularly limited.

The materials constituting the base solid ink layer and the pattern layer 4 are not particularly limited. For example, printing inks or coating agents obtained by dissolving or dispersing a matrix and a colorant such as a dye or pigment in a solvent can be used. As the matrix, for example, various synthetic resins such as oil-based nitrocellulose resin, two-liquid type urethane resin, acrylic resin, styrene resin, polyester resin, urethane resin, polyvinyl resin, alkyd resin, epoxy resin, melamine resin, fluorine resin, silicone resin, and rubber resin, or mixtures or copolymers thereof can be used. In addition, as the colorant, for example, inorganic pigments such as carbon black, titanium white, zinc oxide, red oxide, yellow lead, Prussian blue, and cadmium red, organic pigments such as azo pigments, lake pigments, anthraquinone pigments, phthalocyanine pigments, isoindolinone pigments, and dioxazine pigments, or mixtures thereof can be used. Examples of the solvent that can be used include toluene, xylene, ethyl acetate, butyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, water, and mixtures thereof.

In addition, functional additives such as extender pigments, plasticizers, dispersants, surfactants, tackifiers, adhesion aids, drying agents, hardeners, hardening accelerators, and hardening retarders may be added to the base solid ink layer and the pattern layer 2 in order to impart various functions.
Here, the base solid ink layer and the design layer 2 can be formed by various printing methods such as gravure printing, offset printing, screen printing, electrostatic printing, inkjet printing, etc. In addition, since the base solid ink layer covers the entire surface of the base layer 1, it can also be formed by various coating methods such as roll coating, knife coating, microgravure coating, die coating, etc. These printing and coating methods may be selected separately depending on the layer to be formed, but it is more efficient to select the same method and process them all at once.

<Transparent resin layer 5>
The resin material used as the main component of the transparent resin layer 5 is preferably made of an olefin-based resin, and in addition to polypropylene, polyethylene, polybutene, etc., α-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-pent ... Examples of suitable copolymers include those obtained by homopolymerizing or copolymerizing two or more of α-olefins (such as ethylene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc.) and those obtained by copolymerizing ethylene or α-olefins with other monomers, such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, etc. Furthermore, when it is intended to improve the surface strength of the decorative sheet 10, it is preferable to use a highly crystalline polypropylene resin.
In this specification, the term "main component" refers to 90% by mass or more of the target material, unless otherwise specified.

When the transparent resin layer 5 is provided, the thickness of the transparent resin layer 5 is preferably in the range of 50 μm to 100 μm. When the thickness of the transparent resin layer 5 is less than 50 μm, the effect of improving the scratch resistance and weather resistance of the surface of the transparent resin layer 5 is low, and there is a possibility that the purpose of providing the transparent resin layer 5 is reduced. When the thickness of the transparent resin layer 5 is more than 100 μm, problems such as whitening and cracking during bending may occur.
However, when the topcoat layer 6 is provided on the transparent resin layer 5, the thickness of the transparent resin layer 5 may be less than 50 μm.
In addition, the resin composition constituting the transparent resin layer 5 may contain various functional additives, such as a heat stabilizer, a light stabilizer, an antiblocking agent, a catalyst trap, a colorant, a light scattering agent, and a gloss adjuster, as necessary. These various functional additives can be appropriately selected from well-known additives.

<Top coat layer 6>
When further improvement in scratch resistance or adjustment of gloss is required, a top coat layer 4 can be provided on the surface of the transparent resin layer 3 .
The resin material as the main component of the topcoat layer 6 can be appropriately selected from polyurethane, acrylic silicone, fluorine, epoxy, vinyl, polyester, melamine, aminoalkyd, urea, and other resin materials. The form of the resin material is not particularly limited, and may be water-based, emulsion, solvent-based, or the like. The curing method may also be appropriately selected from one-liquid type, two-liquid type, ultraviolet curing method, and the like.

As the resin material used as the main component of the topcoat layer 6, a urethane-based resin using isocyanate is suitable from the viewpoints of workability, cost, cohesive strength of the resin itself, etc. As the isocyanate, for example, a curing agent such as an adduct, biuret, or isocyanurate, which is a derivative of tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), diphenylmethane diisocyanate (MDI), lysine diisocyanate (LDI), isophorone diisocyanate (IPDI), bis(isocyanatemethyl)cyclohexane (HXDI), trimethylhexamethylene diisocyanate (TMDI), etc., can be appropriately selected and used. However, in consideration of weather resistance, a curing agent based on hexamethylene diisocyanate (HMDI) or isophorone diisocyanate (IPDI) having a linear molecular structure is suitable. In addition, when trying to improve the surface hardness, it is preferable to use a resin that is cured by active energy rays such as ultraviolet rays or electron beams. These resins can be used in combination with each other. For example, by using a hybrid type of thermosetting and photocuring, it is possible to improve the surface hardness, suppress the cure shrinkage, and improve the adhesion.

A gloss regulator can be added to the topcoat layer 6 to adjust the gloss. The gloss regulator may be a known, commercially available product. For example, fine particles made of inorganic materials such as silica, glass, alumina, calcium carbonate, barium sulfate, etc. may be used. Alternatively, fine particles made of organic materials such as acrylic may be used. However, when high transparency is required, it is desirable to use fine particles of highly transparent silica, glass, acrylic, etc. In particular, among fine particles such as silica and glass, gloss regulators that are not solid spherical particles but have low bulk density formed by secondary aggregation of fine primary particles have a high matting effect relative to the amount added. Therefore, by using such gloss regulators, the amount of gloss regulator added can be reduced.

In order to impart various functions to the topcoat layer 4, functional additives such as antibacterial agents and antifungal agents may be added. Also, an ultraviolet absorber and a light stabilizer may be added as necessary. As the ultraviolet absorber, for example, a benzotriazole-based, benzoate-based, benzophenone-based, triazine-based, or cyanoacrylate-based agent may be used. As the light stabilizer, a hindered amine-based agent may be used.
The thickness of the topcoat layer 4 is preferably in the range of 3 μm to 15 μm. If the thickness of the topcoat layer 4 is less than 3 μm, the effect of improving scratch resistance is low, and there is a possibility that the purpose of providing the topcoat layer 4 is reduced. If the thickness of the topcoat layer 4 exceeds 15 μm, cracks or breaks may occur during bending, which may cause design problems or problems of deterioration of weather resistance.

<Actions and other details>
(1) The decorative sheet 10 of the present embodiment is a base layer containing an inorganic pigment and a polyolefin resin, the base layer containing a triazine-based ultraviolet absorber, the triazine-based ultraviolet absorber containing a first hydroxyphenyltriazine-based ultraviolet absorber (UVA-A) having a structure represented by general formula (1) and a second hydroxyphenyltriazine-based ultraviolet absorber (UVA-B) having a structure represented by general formula (2), the contents of the first hydroxyphenyltriazine-based ultraviolet absorber (UVA-A) and the second hydroxyphenyltriazine-based ultraviolet absorber (UVA-B) being in a mass ratio (UVA-A/UVA-B) of 10/90 to 90/10, and the average absorbance within a wavelength range of 450 nm or more and 800 nm or less is in a range of 1.0 to 2.0.
According to this configuration, by adding the triazine-based ultraviolet absorber, it is possible to provide a decorative sheet 10 that has weather resistance, hiding properties, and bleed-out resistance.

(2) In the decorative sheet 10 of the present embodiment, the base layer 1 preferably contains a hindered amine light stabilizer.
This configuration can further improve weather resistance.
(3) In the decorative sheet 10 of this embodiment, it is preferable that the value [C × D/100] obtained by dividing the product of the thickness C μm of the base layer 1 and the content D of the inorganic pigment by 100 is in the range of 0.1 or more and 100 or less.
According to this configuration, it is possible to provide a decorative sheet 10 with further improved weather resistance, hiding power, and bleed-out resistance.

(4) In the decorative sheet 10 of this embodiment, it is preferable that the sum of the content E mass % of the first ultraviolet absorbent and the content F mass % of the second ultraviolet absorbent is 0.1 or more and 1.5 or less.
This configuration can further improve weather resistance.
(5) In the decorative sheet 10 of this embodiment, it is preferable that a pattern layer 4 is laminated on one surface of the base layer 1 .
According to this configuration, the design of the decorative sheet 10 can be improved.
(6) In the decorative sheet 10 of this embodiment, at least one of a transparent resin layer 3 and a top coat layer 4 is laminated on one side of the base layer 1, and it is preferable that the total thickness of the decorative sheet 10 is in the range of 100 μm or more and 250 μm or less.
With this configuration, problems such as peeling over time caused by insufficient adhesive strength due to a marked deterioration in conformity to the edge faces and layered portions of the wood substrate during wrapping can be suppressed.

Specific examples of the decorative sheet 10 of this embodiment are described below.

Example 1
As the raw material of the base layer 1 which is a colored sheet, 30 parts by mass of random polypropylene resin containing 4% ethylene component and having a melt flow rate (MFR) of 12 g/10 min (230°C) was mixed with 35 parts by mass of highly crystalline homopolypropylene resin having a pentad fraction of 97.8%, a melt flow rate (MFR) of 15 g/10 min (230°C) and a molecular weight distribution MWD (Mw/Mn) of 2.3, and 35 parts by mass of titanium oxide pigment as an inorganic pigment, and further a light stabilizer (Tinuvin XT55; BAS A resin containing 0.5 parts by mass of a compound represented by the following formula (4) (Tinosorb S; manufactured by BASF Japan Ltd.) as a hydroxyphenyltriazine-based ultraviolet absorber, 0.25 parts by mass of a compound represented by the following formula (5) (KEMISORB102; manufactured by Chemipro Chemical Co., Ltd.) as a hydroxyphenyltriazine-based ultraviolet absorber, and 0.25 parts by mass of the compound represented by the following formula (5) (KEMISORB102; manufactured by Chemipro Chemical Co., Ltd.) as a hydroxyphenyltriazine-based ultraviolet absorber was extruded using a melt extruder to form a base layer 1 made of a 100 μm colored polypropylene film, and a decorative sheet was prepared.

Example 2
The above-mentioned highly crystalline homopolypropylene resin was mixed with 67.5 parts by mass of titanium oxide pigment as an inorganic pigment, and the thickness of the above-mentioned substrate layer was set to 20 μm. Except for this, the substrate layer 1 was extruded using a melt extruder in the same manner as in Example 1 to form a film, and a decorative sheet was obtained.
Example 3
The above-mentioned highly crystalline homopolypropylene resin was mixed with 30 parts by mass of titanium oxide pigment as an inorganic pigment, and the thickness of the above-mentioned base layer was set to 250 μm. Except for this, the base layer was extruded using a melt extruder in the same manner as in Example 1 to form a base layer 1, which was then used as a decorative sheet.

Example 4
Except for adding 0.45 parts by mass of the compound represented by the above formula (4) as the above ultraviolet absorber and 0.05 parts by mass of the compound represented by the above formula (5) as the above ultraviolet absorber, the same procedure as in Example 1 was used to form a base material layer 1 by extrusion molding using a melt extruder, and a decorative sheet was obtained.
Example 5
Except for adding 0.05 parts by mass of the compound represented by the above formula (4) as the above ultraviolet absorber and 0.45 parts by mass of the compound represented by the above formula (5) as the above ultraviolet absorber, the same procedure as in Example 1 was used to form a base material layer 1 by extrusion molding using a melt extruder, and a decorative sheet was obtained.

Example 6
The above-mentioned highly crystalline homopolypropylene resin was mixed with 67.5 parts by mass of titanium oxide pigment as an inorganic pigment, and the thickness of the above-mentioned base layer was set to 12 μm. Except for this, the base layer was extruded using a melt extruder in the same manner as in Example 1 to form a base layer 1, which was then used as a decorative sheet.
(Example 7)
The above-mentioned highly crystalline homopolypropylene resin was mixed with 20 parts by mass of titanium oxide pigment as an inorganic pigment, and the thickness of the above-mentioned base layer was set to 12 μm. Except for this, the base layer was extruded using a melt extruder in the same manner as in Example 1 to form a base layer 1, which was then used as a decorative sheet.

(Example 8)
Except for adding 0.025 parts by mass of the compound represented by the above formula (4) as the above ultraviolet absorber and 0.025 parts by mass of the compound represented by the above formula (5) as the above ultraviolet absorber, the same procedure as in Example 1 was used to form a base layer 1 by extrusion molding using a melt extruder, and a decorative sheet was obtained.
Example 9
Except for adding 0.05 parts by mass of the compound shown in the above formula (4) as the above-mentioned ultraviolet absorber and 0.05 parts by mass of the compound shown in the above formula (5) as the above-mentioned ultraviolet absorber, the substrate layer 1 was formed by extrusion molding using a melt extruder in the same manner as in Example 1, and a decorative sheet was obtained.

(Example 10)
Except for adding 0.5 parts by mass of the compound shown in the above formula (4) as the above ultraviolet absorber and 0.5 parts by mass of the compound shown in the above formula (5) as the above ultraviolet absorber, the same procedure as in Example 1 was used to extrude using a melt extruder to form a base layer 1, which was then used as a decorative sheet.
(Example 11)
Except for adding 0.75 parts by mass of the compound shown in the above formula (4) as the above ultraviolet absorber and 0.75 parts by mass of the compound shown in the above formula (5) as the above ultraviolet absorber, the same procedure as in Example 1 was used to form a base layer 1 by extrusion molding using a melt extruder, and a decorative sheet was obtained.
Example 12
Except for adding 1.0 part by mass of the compound shown in the above formula (4) as the above ultraviolet absorber and 1.0 part by mass of the compound shown in the above formula (5) as the above ultraviolet absorber, the same procedure as in Example 1 was used to form a base material layer 1 by extrusion molding using a melt extruder, and a decorative sheet was obtained.

(Comparative Example 1)
The same procedure as in Example 1 was repeated, except that 0.5 parts by mass of the compound shown in the above formula (4) was added as the ultraviolet absorber, and no compound shown in the above formula (5) was added as the ultraviolet absorber, to form a base layer 1, which was then used as a decorative sheet.
(Comparative Example 2)
The same procedure as in Example 1 was repeated, except that the compound shown in the above formula (4) was not added as the above ultraviolet absorber, and 0.5 parts by mass of the compound shown in the above formula (5) was added as the above ultraviolet absorber, to form a base layer 1, which was then used as a decorative sheet.

(Comparative Example 3)
The above-mentioned ultraviolet absorber was replaced with a benzotriazole-based ultraviolet absorber (Tinuvin 326; manufactured by BASF Corporation) and added in an amount of 0.5 parts by mass. Except for this, the substrate layer 1 was formed by extrusion molding using a melt extruder in the same manner as in Example 1, and a decorative sheet was obtained.
(Comparative Example 4)
A base layer 1 was formed by extrusion molding using a melt extruder in the same manner as in Example 1, except that the above-mentioned ultraviolet absorbing agent was not added, and a decorative sheet was obtained.

(Comparative Example 5)
The above-mentioned highly crystalline homopolypropylene resin was mixed with 20 parts by mass of titanium oxide pigment as an inorganic pigment, and the thickness of the above-mentioned base layer was set to 250 μm. Except for this, the base layer was extruded using a melt extruder in the same manner as in Example 1 to form a base layer 1, which was then used as a decorative sheet.
(Comparative Example 6)
The above-mentioned highly crystalline homopolypropylene resin was mixed with 68 parts by mass of titanium oxide pigment as an inorganic pigment, and the thickness of the above-mentioned substrate layer was set to 10 μm. Except for this, the substrate layer 1 was extruded using a melt extruder in the same manner as in Example 1 to form a decorative sheet.

(evaluation)
For the above Examples 1 to 12 and Comparative Examples 1 to 4, the weather resistance, hiding power, and bleed-out resistance of the base layer 1 serving as a decorative sheet were evaluated.

<Weather resistance>
The appearance of the decorative sheet after the accelerated weathering test was visually observed, and the discoloration of the pattern and the change in appearance of the protective film were evaluated according to the following criteria: The accelerated weathering test was performed using an Eye Super UV Tester (SUV-W161; Iwasaki Electric Co., Ltd.) at a black panel temperature of 63°C and an illuminance of 65 mW/ ^cm2 , with 30 cycles consisting of 20 hours of UV irradiation + 4 hours of condensation.

(Changes in appearance of substrate)
○: No difference in appearance was observed.
△: Cracks were observed in the base layer (small degree).
×: Cracks were observed in the base layer (large degree).

<Concealment>
The evaluation of the hiding power was judged by the color difference measured with a spectrophotometer (530JP/LP) manufactured by X-rite and a hiding test paper (byco-chart high brightness 2A) manufactured by BYK-GARDNER on a white background and a black background. The smaller the color difference value, the better the hiding power. When the hiding power is less than 0.3, it is marked as "◎", when it is 0.3 or more and less than 0.5, it is marked as "〇", when it is 0.5 or more and less than 1.0, it is marked as "△", and when it is 1.0 or more, it is marked as "×". In addition, if it is rated as "〇" or more, there is no practical problem for generally used substrates in general, but when it is rated as "△", it is not suitable for some substrates, but there is no practical problem for the majority of substrates. It is preferable to be rated as "〇" or more.

<Bleed-out resistance>
The bleed-out resistance was evaluated by testing the composition in a high-temperature incubator (model HT310, manufactured by Espec Corp.) at 60° C. for 2000 hours.
The case where there was no change in gloss or stickiness on the surface of the base layer was rated as "◯", the case where there was a visible change in gloss on the surface was rated as "Δ", and the case where the surface was sticky was rated as "×".
In addition, a rating of "△" or higher poses no practical problem, but a rating of "◯" or higher is preferable.
The evaluation results are shown in Table 1.

As can be seen from Table 1, the decorative sheets of Examples 1, 3 to 5, and 7 to 12 are highly weather resistant and bleed-out resistant despite their high inorganic pigment loadings. Also, the decorative sheets of Examples 2 and 6 are thin and have low inorganic pigment loadings, but are able to achieve the required performance with a sufficient margin.
On the other hand, it was confirmed that the weather resistance deteriorated depending on the amount of ultraviolet absorber and the type of weather resistance agent in Comparative Examples 1 to 4. Also, it was found that in Comparative Examples 5 and 6, the required performance was not achieved unless the average absorbance at wavelengths of 450 nm to 800 nm was within a certain range.

From the above, it is clear that the decorative sheets of Examples 1 to 12 are decorative sheets that have all of high weather resistance, high hiding power, and bleed-out resistance.
The decorative sheet of the present invention is not limited to the above-mentioned embodiments and examples, and various modifications are possible without departing from the characteristics of the invention.

REFERENCE SIGNS LIST 1 Base material layer 2 Colored layer 3 Skin layer 4 Design layer 5 Transparent resin layer 6 Surface protection layer 7 Dry lamination adhesive layer 8 Adhesive layer with substrate 10 Decorative sheet B Substrate

Claims (8)

A substrate layer containing an inorganic pigment and a polyolefin resin, the substrate layer containing a triazine-based ultraviolet absorber,
The triazine-based ultraviolet absorber contains a first hydroxyphenyltriazine-based ultraviolet absorber (UVA-A) having a structure represented by the following general formula (1) and a second hydroxyphenyltriazine-based ultraviolet absorber (UVA-B) having a structure represented by the following general formula (2):
the mass ratio (UVA-A/UVA-B) of the first hydroxyphenyltriazine ultraviolet absorber (UVA-A) to the second hydroxyphenyltriazine ultraviolet absorber (UVA-B) is within a range of 10/90 to 90/10;
The average absorbance in the wavelength range of 450 nm or more and 800 nm or less is 1.0 or more and 2.0 or less,
A decorative sheet, characterized in that the sum of the content E mass % of the first ultraviolet absorbent and the content F mass % of the second ultraviolet absorbent is 0.1 or more and 1.5 or less .

(In general formula (1), R1 to R3 each independently represent a hydrogen atom, a methyl group, a phenyl group, or an alkoxy group, and at least two of them are an alkoxy group having 6 to 18 carbon atoms; R4 and R5 each independently represent a hydroxyl group, a methyl group, or a hydrogen atom; and R6 to R8 each independently represent a methyl group or a hydrogen atom.)

(In general formula (2), R1 is an alkoxy group having 8 to 18 carbon atoms, and R2 to R5 are each independently a hydrogen atom or a methyl group.) The decorative sheet according to claim 1, characterized in that the substrate layer contains a hindered amine light stabilizer. The decorative sheet according to claim 1 or 2, characterized in that the product of the thickness C μm of the base layer and the content D mass % of the inorganic pigment divided by 100 [C × D / 100] is in the range of 0.5 to 100. The decorative sheet according to any one of claims 1 to 3 , characterized in that the ultraviolet absorber (UVA-A) has a structure represented by the following general formula (3):

(In general formula (3), R1 and R2 each represent an alkoxy group having 8 to 18 carbon atoms, R3 represents an alkoxy group having 1 to 4 carbon atoms, R4 represents a hydroxyl group, and R5 to R8 each represent a hydrogen atom.) The decorative sheet according to any one of claims 1 to 4 , wherein the ultraviolet absorber (UVA-A) has a structure represented by the following formula (4):

The decorative sheet according to any one of claims 1 to 5 , wherein the ultraviolet absorbing agent (UVA-B) has a structure represented by the following formula (5).

7. The decorative sheet according to claim 1, further comprising a pattern layer laminated on one surface of the base layer. A decorative sheet according to any one of claims 1 to 7, characterized in that at least one of a transparent resin layer and a top coat layer is laminated on one side of the base layer, and the total thickness of the sheet is within the range of 100 μm or more and 250 μm or less.

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