Decorative sheet

Abstract

To provide a decorative sheet capable of suppressing occurrence of crack on a surface protective layer at bending, while securing scratch resistance of a surface protective layer.SOLUTION: A decorative sheet 1 is composed of a thermoplastic resin base sheet 11, a patterned layer 12, a transparent thermoplastic resin layer 13, and a surface protection layer 14, which are sequentially laminated. The surface protective layer 14 consists of a mixture of a curable resin that includes at least one of a thermosetting resin and a radiation-curable resin, and a curing agent that has a longer side chain attached to the six-membered ring than hexamethylene diisocyanate (HDI) nucleated type.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cosmetic sheet.

Background Art

[0002] Patent Document 1 discloses a decorative sheet used for building materials and the like. In the decorative sheet of Patent Document 1, a base sheet made of a thermoplastic resin, a pattern layer, a transparent thermoplastic resin layer, and a surface protection layer are laminated in order. Such a decorative sheet is used as a flooring material or the like by bonding it to various adherends such as a wooden base material. In the decorative sheet used as a flooring material, the scratch resistance of the surface protection layer is particularly required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the surface protection layer of this type of decorative sheet, a mixture of a curable resin and a curing agent is often used. Conventionally, in consideration of the scratch resistance of the surface protection layer, a mixture of hexamethylene diisocyanate (HDI) nurate type and xylylene diisocyanate (XDI) is often used as the curing agent for the surface protection layer. However, in the decorative sheet using the above-mentioned curing agent, when the decorative sheet is bent, there is a problem that cracks occur in the bent portion of the surface protection layer. Bending of the decorative sheet occurs, for example, in wrapping processing in which a plate-shaped adherend is wrapped with the decorative sheet, and thus the occurrence of cracks in the surface protection layer is not preferable.

[0005] In view of the above problems, an object of the present invention is to provide a decorative sheet that can suppress the occurrence of cracks in the surface protection layer even when bent while ensuring the scratch resistance of the surface protection layer.

Means for Solving the Problem

[0006] One aspect of the present invention is a decorative sheet in which a base sheet made of a thermoplastic resin, a pattern layer, a transparent thermoplastic resin layer, and a surface protective layer are laminated in this order. The surface protective layer is composed of a curable resin containing at least one of a thermosetting resin and a radiation-curable resin, and a curing agent having a longer side chain attached to the six-membered ring than the hexamethylene diisocyanate (HDI) nurate type.

Advantages of the Invention

[0007] According to the present invention, while ensuring the scratch resistance of the surface protective layer, it is possible to prevent cracks from occurring in the surface protective layer even when bent.

Brief Description of the Drawings

[0008]

Figure 1

Mode for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings used in the following description may show the main part enlarged for convenience of understanding the features of the present invention, and the dimensional ratios and the like of each component are not necessarily the same as the actual ones.

[0010] As shown in FIG. 1, the decorative sheet 1 of the present embodiment includes a base sheet 11 made of a thermoplastic resin, a pattern layer 12, a transparent thermoplastic resin layer 13, and a surface protective layer 14. The base sheet 11 made of a thermoplastic resin, the pattern layer 12, the transparent thermoplastic resin layer 13, and the surface protective layer 14 are laminated in this order. Further, the decorative sheet 1 further includes an adhesive layer 15 interposed between the pattern layer 12 and the transparent thermoplastic resin layer 13.

[0011] The base sheet 11 made of a thermoplastic resin and the pattern layer 12 are both colored. On the other hand, the transparent thermoplastic resin layer 13, the surface protective layer 14, and the adhesive layer 15 are all transparent. Therefore, when the decorative sheet 1 is viewed from the surface protective layer 14 side, the pattern layer 12 can be visually recognized through the surface protective layer 14, the transparent thermoplastic resin layer 13, and the adhesive layer 15.

[0012] Further, the decorative sheet 1 further includes a primer layer 16 that overlaps the second surface 11b of the base sheet 11 made of a thermoplastic resin, which is opposite to the surface protective layer 14 side. Hereinafter, each layer will be described.

[0013] <Base Sheet Made of Thermoplastic Resin> The base sheet 11 made of a thermoplastic resin contains a thermoplastic resin. The thermoplastic resin contained in the base sheet 11 made of a thermoplastic resin may be a known one. The thermoplastic resin may be, for example, a polyolefin resin such as polyethylene (PE) or polypropylene (PP). The thermoplastic resin contained in the base sheet 11 made of a thermoplastic resin can be appropriately selected in terms of its grade and composition, for example, considering the required environmental compatibility, processability, price, ease of seating, printability, or bendability. The thermoplastic resin contained in the base sheet 11 made of a thermoplastic resin may be only one kind or two or more kinds. When there are two or more kinds of the thermoplastic resins, their combinations and ratios can be arbitrarily selected.

[0014] The base sheet 11 made of a thermoplastic resin may contain other components that do not correspond to the thermoplastic resin. The other components contained in the base sheet 11 made of a thermoplastic resin may be only one kind or two or more kinds. When there are two or more kinds, their combinations and ratios can be arbitrarily selected. The base sheet 11 made of a thermoplastic resin of the present embodiment contains a colorant as another component. The colorant may be a known one and may be, for example, either a pigment or a dye. Other components contained in the thermoplastic resin-based substrate sheet 11 are not limited to colorants and can be arbitrarily selected according to the purpose. Examples of other components contained in the thermoplastic resin-based substrate sheet 11 include fillers, flame retardants, antioxidants, lubricants, foaming agents, etc.

[0015] The thermoplastic resin-based substrate sheet 11 is not limited to being a single layer as exemplified in FIG. 1, and may be, for example, a plurality of layers of two or more layers. When the thermoplastic resin-based substrate sheet 11 is a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited.

[0016] The thickness of the thermoplastic resin-based substrate sheet 11 is not particularly limited, but may be, for example, 40 to 150 μm, or may be 50 to 100 μm.

[0017] <Pattern layer> The pattern layer 12 has a design property that can be visually recognized when the decorative sheet 1 is viewed from the surface protection layer 14 side. The patterns and designs of the visually recognized pattern layer 12 may be, for example, one or a combination of two or more selected from wood grain patterns, cork patterns, stone (e.g., marble) grain patterns, sand grain patterns, tile sticker patterns, brick stack patterns, cloth patterns, leather grain patterns, geometric figures, characters, symbols, abstract patterns, and solid colors. The pattern layer 12 may be formed, for example, by printing on the first surface 11a of the thermoplastic resin-based substrate sheet 11 using ink.

[0018] <Transparent thermoplastic resin layer> The transparent thermoplastic resin layer 13 is transparent. Therefore, when the decorative sheet 1 is viewed from the surface protection layer 14 side, the pattern layer 12 disposed below the transparent thermoplastic resin layer 13 can be visually recognized. The transparent thermoplastic resin layer 13 is mainly provided to protect the pattern layer 12 and the thermoplastic resin-based substrate sheet 11. In addition, the transparent thermoplastic resin layer 13 also has a role of adjusting the texture of the pattern layer 12 visually recognized through the transparent thermoplastic resin layer 13 to adjust the appearance of the decorative sheet 1.

[0019] The transparent thermoplastic resin layer 13 has a recess 131 formed on the first surface 13a on the surface protection layer 14 side of the transparent thermoplastic resin layer 13. The recess 131 is recessed from the first surface 13a of the transparent thermoplastic resin layer 13. The recess 131 may be dot-shaped or groove-shaped. Further, although the recess 131 is formed in a V-shaped cross section as illustrated in FIG. 1, it may be formed in an arbitrary cross-sectional shape such as a U-shaped cross section. The recess 131 may be formed in advance to form a recess 141 in the surface protection layer 14 described later, or may be formed simultaneously when the recess 141 of the surface protection layer 14 is formed. If the recess 141 of the surface protection layer 14 can be appropriately formed, the recess 131 of the transparent thermoplastic resin layer 13 may not be formed.

[0020] The transparent thermoplastic resin layer 13 contains a thermoplastic resin. The thermoplastic resin contained in the transparent thermoplastic resin layer 13 may be a known one. The thermoplastic resin may be, for example, a polyolefin resin such as polyethylene (PE) or polypropylene (PP). The transparent thermoplastic resin layer 13 may be either colorless or colored as long as it is transparent.

[0021] The transparent thermoplastic resin layer 13 is not limited to being a single layer as illustrated in FIG. 1, and may be, for example, a plurality of layers of two or more layers. When the transparent thermoplastic resin layer 13 is a plurality of layers, these plurality of layers may be the same as or different from each other, and the combination of these plurality of layers is not particularly limited.

[0022] The thickness of the transparent thermoplastic resin layer 13 is not particularly limited, but may be, for example, 30 to 200 μm.

[0023] <Adhesive layer> The adhesive layer 15 adheres the pattern layer 12 and the transparent thermoplastic resin layer 13 to improve the adhesion between the pattern layer 12 and the transparent thermoplastic resin layer 13. The adhesive layer 15 is transparent. Therefore, when the decorative sheet 1 is viewed from the surface protection layer 14 side, the pattern layer 12 disposed below the adhesive layer 15 can be visually recognized. The adhesive layer 15 may be either colorless or colored as long as it is transparent. The adhesive layer 15 may be a known one, for example, one containing a transparent adhesive resin.

[0024] <Surface protection layer> The surface protection layer 14 is a layer that constitutes the outermost surface of the decorative sheet 1 and protects the layers disposed below the surface protection layer 14. The surface protection layer 14 has scratch resistance that is difficult to be scratched. The surface protection layer 14 is transparent. Therefore, when the decorative sheet 1 is viewed from the surface protection layer 14 side, the layers disposed below the surface protection layer 14 can be visually recognized. The surface protection layer 14 may be either colorless or colored as long as it is transparent.

[0025] The surface protection layer 14 has a recess 141 formed on the first surface 14a of the surface protection layer 14 that constitutes the outermost surface of the decorative sheet 1. The recess 141 is recessed from the first surface 14a of the surface protection layer 14. The recess 141 may be dot-shaped or groove-shaped. Further, although the recess 141 is formed in a V-shaped cross section as illustrated in FIG. 1, it may be formed in an arbitrary cross-sectional shape such as a U-shaped cross section. The recess 141 of the surface protection layer 14 illustrated in FIG. 1 is formed so as to follow the recess 131 of the transparent thermoplastic resin layer 13 in which the recess 141 is formed. Note that the recess 141 of the surface protection layer 14 may be formed, for example, without being affected by the shape of the first surface 14a of the surface protection layer 14. The recess 141 of the surface protection layer 14 functions as an anti-slip. Note that the surface protection layer 14 may not have the recess 141, for example.

[0026] The surface protection layer 14 is made of a mixture of a curable resin and a curing agent. The curable resin in the surface protective layer 14 may be either a thermosetting resin or an ionizing radiation curable resin. In this specification, "ionizing radiation" means an electromagnetic wave or a charged particle beam having energy capable of causing a curing reaction of the ionizing radiation curable resin. Specific examples thereof include ultraviolet rays, electron beams, visible light, X-rays, ion beams, and the like.

[0027] Examples of the thermosetting resin in the surface protective layer 14 include polyfunctional acrylate urethane resins, polyester resins, and the like.

[0028] Examples of the ionizing radiation curable resin in the surface protective layer 14 include transparent resins mainly composed of prepolymers, oligomers, or monomers having radical polymerizable double bonds capable of undergoing a polymerization crosslinking reaction upon irradiation with ionizing radiation in their molecules. Each of the above-mentioned prepolymers, oligomers, and monomers may be only one kind, or may be two or more kinds. When there are two or more kinds of prepolymers, oligomers, and monomers respectively, their combinations and ratios can be arbitrarily selected.

[0029] The curing agent in the surface protective layer 14 is a curing agent having a longer side chain attached to the six-membered ring than the hexamethylene diisocyanate (HDI) nurate type. The curing agent does not contain xylylene diisocyanate (XDI). Examples of such a curing agent include urethane-based flexible curing agents. When curing a mixture of the above-mentioned curable resin and the curing agent, the curing agent has a function of moderately suppressing the shrinkage of the mixture as compared with conventional curing agents. Note that the "conventional curing agent" is a mixture of hexamethylene diisocyanate (HDI) nurate type and xylylene diisocyanate (XDI). Examples of the "conventional curing agent" include urethane-based curing agents.

[0030] The pencil hardness of the surface protective layer 14 is 2B or more. The pencil hardness of the surface protective layer 14 is the result measured by a pencil hardness test in accordance with JIS K5600.

[0031] The thickness of the surface protective layer 14 is not particularly limited, and may be, for example, 1 to 5 μm.

[0032] <Primer layer> The primer layer 16 is a layer for fixing the decorative sheet 1 to the application site for the purpose of the decorative sheet 1. By providing the decorative sheet 1 with the primer layer 16, when using the decorative sheet 1, for example, the step of primer-treating the second surface 11b of the base material sheet 11 made of a thermoplastic resin can be omitted. The decorative sheet 1 may not include the primer layer 16, for example.

[0033] The decorative sheet 1 of the present embodiment configured as described above can form a decorative material such as for flooring by being bonded to various adherends by the primer layer 16. As a specific example of the decorative material, for example, when the adherend is plate-shaped, a decorative board such as for flooring can be mentioned. The decorative sheet 1 may be bonded to the adherend, for example, by performing a wrapping process that wraps the plate-shaped adherend.

[0034] As described above, in the decorative sheet 1 of the present embodiment, the surface protective layer 14 is composed of a mixture of a curable resin containing at least one of a thermosetting resin and a radiation-curable resin, and a curing agent having a longer side chain attached to the six-membered ring than the hexamethylene diisocyanate (HDI) nurate type. Therefore, when the above curable resin and curing agent are mixed and the mixture is cured, the shrinkage of the mixture can be moderately suppressed. Thereby, compared with the conventional surface protective layer 14, the flexibility of the surface protective layer 14 can be moderately increased. Therefore, while ensuring the scratch resistance of the surface protective layer 14, it is possible to suppress the occurrence of cracks in the surface protective layer 14 even when bent.

[0035] Also, in the decorative sheet 1 of the present embodiment, the pencil hardness of the surface protective layer 14 is 2B or more. Thereby, the scratch resistance of the surface protective layer 14 can be sufficiently ensured.

[0036] 〔Experimental example〕 Hereinafter, the cosmetic sheet according to the present invention will be further described using experimental examples (Example 1, Comparative Examples 1 and 2). The technical scope of the present invention is not limited in any way by the specific contents of the experimental examples.

[0037] [Example 1] The cosmetic sheet of Example 1 was configured by laminating a base sheet made of a thermoplastic resin, a pattern layer, an adhesive layer, a transparent thermoplastic resin layer, and a surface protective layer in this order. The base sheet made of a thermoplastic resin was a 55-μm-thick sheet made of polyethylene (PE). A pattern layer was formed by applying urethane-based printing ink to the first surface of the base sheet made of a thermoplastic resin. An adhesive layer was formed by applying an adhesive onto the pattern layer.

[0038] Furthermore, a transparent thermoplastic resin layer was formed by laminating molten polypropylene (PP) onto the adhesive layer while extruding it. At the time of forming the transparent thermoplastic resin layer, embossing was performed on the surface (first surface) of the transparent thermoplastic resin layer simultaneously with the lamination onto the adhesive layer to form recesses. Also, a surface protective layer was formed by overlaying a mixture of an ionizing radiation curable resin and a urethane-based flexible curing agent on the transparent thermoplastic resin layer. As the ionizing radiation curable resin, a UV curable resin that cures by ultraviolet rays was adopted. As the urethane-based flexible curing agent, a flexible curing agent manufactured by DIC Corporation was adopted. Recesses imitating the recesses of the transparent thermoplastic resin layer were formed on the surface (first surface) of the surface protective layer. Thus, the cosmetic sheet of Example 1 was obtained.

[0039] [Comparative Example 1] The cosmetic sheet of Comparative Example 1 was produced in the same manner as the cosmetic sheet of Example 1, except that a surface protective layer was formed by overlaying a mixture of an ionizing radiation curable resin and a urethane-based curing agent on the transparent thermoplastic resin layer. As the ionizing radiation curable resin, the same UV curable resin as in Example 1 was adopted. As the urethane-based curing agent, W325N manufactured by DIC Corporation was adopted.

[0040] [Comparative Example 2] The cosmetic sheet of Comparative Example 2 was produced in the same manner as the cosmetic sheet of Example 1, except that a surface protective layer was formed by laminating a mixture of a thermosetting resin and a urethane-based curing agent on a transparent thermoplastic resin layer. W480E manufactured by DIC Corporation was used as the thermosetting resin. The same urethane-based curing agent as in Comparative Example 1 was used.

[0041] <Lapping process> For the cosmetic sheets of Example 1 and Comparative Examples 1 and 2, after performing a lapping process in which a plate-shaped adherend was wrapped with the cosmetic sheet, it was confirmed whether cracks occurred in the portion bent at approximately a right angle (90 degrees) of each cosmetic sheet. As a result of the confirmation, when no cracks were visible in the corresponding portion, it was marked as "○" and considered qualified. Also, when cracks were visible in a part of the corresponding portion, it was marked as "△", and when cracks were visible in the entire corresponding portion, it was marked as "×".

[0042] <Pencil hardness test> For the cosmetic sheets of Example 1 and Comparative Examples 1 and 2, after laminating each cosmetic sheet on a medium-density fiberboard (MDF), the pencil hardness of each cosmetic sheet was evaluated by performing a pencil hardness test in accordance with JIS K5600. It was considered qualified when the pencil hardness was 2B or higher. On the other hand, it was considered unqualified when the pencil hardness was 3B or lower.

[0043] <Hoffman scratch test> For the cosmetic sheets of Example 1 and Comparative Examples 1 and 2, after laminating each cosmetic sheet on a medium-density fiberboard (MDF), using a Hoffman scratch hardness tester (manufactured by BYK-Gardner), the exposed surface (the first surface) of the surface protective layer of each cosmetic sheet was scratched by increasing the applied load in increments of 200 g from 200 g. Each time the load increased, it was confirmed whether there were scratches on each cosmetic sheet. As a result of the confirmation, it was considered qualified when scratches first appeared at 600 g or more. It was considered unqualified when scratches first appeared at less than 600 g.

[0044] <Comprehensive evaluation> For the cosmetic sheets of Example 1 and Comparative Examples 1 and 2, when all three tests, namely the above-mentioned wrapping process, pencil hardness test, and Hoffman scratch test, were passed, it was evaluated as "○ (passed)". On the other hand, when any one of these three tests was not passed, it was evaluated as "× (failed)". Table 1 shows the results of the wrapping process, pencil hardness test, Hoffman scratch test, and comprehensive evaluation for the cosmetic sheets of Example 1 and Comparative Examples 1 and 2.

[0045]

Table 1

[0046] As shown in Table 1, in Comparative Example 1, although the results of both the pencil hardness test and the Hoffman scratch test were passed, the result of the wrapping process was "×". That is, for the cosmetic sheet of Comparative Example 1, although the scratch resistance of the surface protective layer could be ensured, cracks occurred in the surface protective layer due to bending, so the comprehensive evaluation was "× (failed)". In Comparative Example 2, the result of the wrapping process was "○ (passed)", but the results of both the pencil hardness test and the Hoffman scratch test were failed. That is, for the cosmetic sheet of Comparative Example 2, although the occurrence of cracks in the surface protective layer due to bending could be prevented, the scratch resistance of the surface protective layer could not be ensured, so the comprehensive evaluation was "× (failed)".

[0047] On the other hand, in Example 1, the result of the wrapping process was "○ (passed)", and the results of both the pencil hardness test and the Hoffman scratch test were also passed. That is, for the cosmetic sheet of Example 1, the occurrence of cracks in the surface protective layer due to bending could be prevented, and the scratch resistance of the surface protective layer could also be ensured, so the comprehensive evaluation was "○ (passed)".

[0048] As described above, the embodiments according to the present invention have been explained. However, the present invention is not limited to the above embodiments and can be appropriately modified without departing from the gist thereof.

[0049] In the present invention, the pattern layer 12 may be integrally formed on, for example, a base sheet 11 made of a thermoplastic resin. In other words, instead of laminating the pattern layer 12 on the first surface 11a of the base sheet 11 made of a thermoplastic resin, for example, the first surface 11a of the base sheet 11 made of a thermoplastic resin may have a picture or a pattern.

[0050] In the present invention, the decorative sheet 1 may not include, for example, the adhesive layer 15. In this case, the pattern layer 12 and the transparent thermoplastic resin layer 13 may be directly adhered by melting the transparent thermoplastic resin layer 13 or the like.

Explanation of reference numerals

[0051] 1 Decorative sheet 11 Base sheet made of thermoplastic resin 12 Pattern layer 13 Transparent thermoplastic resin layer 14 Surface protection layer

Claims

1. A decorative sheet is formed by laminating a substrate sheet made of a thermoplastic resin, a pattern layer, a transparent thermoplastic resin layer, and a surface protective layer in this order. The surface protective layer is composed of a curable resin containing at least one of a thermosetting resin and a radiation-curable resin, and a curing agent having a longer side chain attached to the six-membered ring than the hexamethylene diisocyanate (HDI) nurate type.

2. The decorative sheet according to claim 1, wherein the pencil hardness of the surface protective layer is 2B or more.

Images