Decorative sheet

Abstract

To provide a decorative sheet having sufficient flaw resistance and hard to generate a crack at the time of bending.SOLUTION: The decorative sheet 1 includes a thermoplastic resin base material sheet 11, a picture pattern layer 12 formed on the thermoplastic resin base material sheet, a transparent thermoplastic resin layer 13 formed on the picture pattern layer, and a surface protective part 20 formed on the transparent thermoplastic resin layer. The surface protective part contains a base resin and a low gloss agent, and has a first protective layer 21 formed on the transparent thermoplastic resin layer and a second protective layer 22 formed on the first protective layer. The base resin of the second protective layer includes a curable resin containing at least one of a thermosetting resin and an ionizing radiation curable resin, and a mixed curing agent obtained by mixing a curing agent in which hexamethylene diisocyanate nurate type and xylylene diisocyanate are mixed and a curing agent having a longer side chain attached to a six-membered ring than the hexamethylene diisocyanate nurate type at a mass ratio of 1:1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a decorative sheet. [Background technology]

[0002] Patent Document 1 discloses a decorative sheet used for building materials, etc. The decorative sheet of Patent Document 1 comprises a thermoplastic resin base sheet, a patterned layer, a transparent thermoplastic resin layer, and a surface protective layer laminated in that order. Such a decorative sheet is attached to various adherends, such as wood substrates, to form the surface of flooring materials and improve their design, etc. Decorative sheets used for flooring materials are particularly required to have scratch resistance in the surface protective layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-163757 Summary of the Invention [Problem to be solved by the invention]

[0004] In the surface protective layer of this type of decorative sheet, cracks may occur in the folded portion of the surface protective layer when the decorative sheet is folded, for example, during a wrapping process in which the decorative sheet is wrapped around a plate-shaped adherend. On the other hand, if cracks are to be prevented during lapping, the scratch resistance of the surface protection layer may become insufficient, and it is not easy to achieve both.

[0005] An object of the present invention is to provide a decorative sheet that has sufficient scratch resistance and is less likely to crack when folded. [Means for solving the problem]

[0006] The present invention is a decorative sheet comprising a thermoplastic resin base sheet, a picture pattern layer formed on the thermoplastic resin base sheet, a transparent thermoplastic resin layer formed on the picture pattern layer, and a surface protection portion formed on the transparent thermoplastic resin layer. The surface protection part has a first protective layer containing a base resin and a low gloss agent and formed on the transparent thermoplastic resin layer, and a second protective layer containing a base resin and a low gloss agent and formed on the first protective layer. The base resin of the second protective layer is composed of a curable resin containing at least one of a thermosetting resin and an ionizing radiation curable resin, and a mixed curing agent obtained by mixing a curing agent obtained by mixing a hexamethylene diisocyanate nurate type curing agent with a xylylene diisocyanate curing agent in a mass ratio of 1:1, and a curing agent having a longer side chain attached to the six-membered ring than the hexamethylene diisocyanate nurate type curing agent. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a decorative sheet that has sufficient scratch resistance and is less likely to crack when folded. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view showing a decorative sheet according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described with reference to FIG. 1, the decorative sheet 1 of this embodiment comprises a thermoplastic resin base sheet 11, a picture / pattern layer 12, a transparent thermoplastic resin layer 13, and a surface protection portion 20. The picture / pattern layer 12, the transparent thermoplastic resin layer 13, and the surface protection portion 20 are formed in this order on the first surface 11a of the thermoplastic resin base sheet 11.

[0010] Both the thermoplastic resin substrate sheet 11 and the picture pattern layer 12 are colored, while the transparent thermoplastic resin layer 13 and the surface protection portion 20 are transparent. Therefore, when the decorative sheet 1 is viewed from the surface protection portion 20 side, the picture pattern layer 12 can be seen through the surface protection portion 20 and the transparent thermoplastic resin layer 13 .

[0011] The decorative sheet 1 also has a primer layer 16 on the second surface 11b of the thermoplastic resin base sheet 11, which is opposite to the first surface 11a. Each layer will be described below.

[0012] <Thermoplastic resin base sheet> The thermoplastic resin substrate sheet 11 contains a thermoplastic resin. The thermoplastic resin contained in the thermoplastic resin substrate sheet 11 may be a known one. The thermoplastic resin may be, for example, a polyolefin resin such as polyethylene (PE) or polypropylene (PP). The grade and composition of the thermoplastic resin contained in the thermoplastic resin substrate sheet 11 can be selected appropriately, taking into consideration, for example, the required environmental compatibility, processability, price, ease of sheeting, printability, or bending processability. The thermoplastic resin substrate sheet 11 may contain only one type of thermoplastic resin, or two or more types of thermoplastic resins. When two or more types of thermoplastic resins are contained, the combination and ratio thereof can be selected arbitrarily.

[0013] The thermoplastic resin substrate sheet 11 may contain other components that are not thermoplastic resins. The other components contained in the thermoplastic resin substrate sheet 11 may be one type only or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily. The thermoplastic resin substrate sheet 11 of this embodiment contains a colorant as another component. The colorant may be a known colorant, such as a pigment or a dye. The other components contained in the thermoplastic resin substrate sheet 11 are not limited to colorants and can be selected arbitrarily depending on the purpose. Examples of other components contained in the thermoplastic resin substrate sheet 11 include fillers, flame retardants, antioxidants, lubricants, and foaming agents.

[0014] The thermoplastic resin substrate sheet 11 is not limited to being a single layer as illustrated in Fig. 1, but may be made up of, for example, two or more layers. When the thermoplastic resin substrate sheet 11 is made up of multiple layers, these multiple layers may be the same or different from one another, and the combination of these multiple layers is not particularly limited.

[0015] The thickness of the thermoplastic resin substrate sheet 11 is not particularly limited, but can be, for example, 40 to 150 μm, or 50 to 100 μm.

[0016] <Pattern layer> The picture pattern layer 12 contributes to the design of the decorative sheet 1 when viewed from the side of the surface protection portion 20. The visible picture or pattern of the picture pattern layer 12 may be, for example, one or a combination of two or more selected from a wood grain pattern, a cork pattern, a stone (e.g., marble) pattern, a sand grain pattern, a tiled pattern, a brickwork pattern, a fabric pattern, a leather-grained pattern, a geometric figure, letters, symbols, an abstract pattern, and a solid color. The picture pattern layer 12 may be formed by printing on the first surface 11a of the thermoplastic resin base sheet 11 using, for example, ink.

[0017] <Transparent thermoplastic resin layer> The transparent thermoplastic resin layer 13 is transparent, so that when the decorative sheet 1 is viewed from the surface protection portion 20 side, the picture pattern layer 12 disposed underneath can be seen. The transparent thermoplastic resin layer 13 mainly functions to protect the picture and pattern layer 12 and the thermoplastic resin substrate sheet 11. The transparent thermoplastic resin layer 13 also adjusts the appearance of the decorative sheet 1 by adjusting the texture of the picture and pattern layer 12 that is visible through the transparent thermoplastic resin layer 13.

[0018] The transparent thermoplastic resin layer 13 has recesses 131 formed on a first surface 13a of the transparent thermoplastic resin layer 13 on the surface protective layer 14 side. The recesses 131 are recessed from the first surface 13a of the transparent thermoplastic resin layer 13. The recesses 131 may be dot-shaped or groove-shaped. In FIG. 1, the recesses 131 are formed with a V-shaped cross section, but they may be formed with any cross-sectional shape, such as a U-shaped cross section. The recess 131 is usually formed before forming the surface protection portion 20 described below, but may be formed after the surface protection portion 20 is completed.

[0019] 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, so long as it is transparent. When forming the transparent thermoplastic resin layer 13 using a film made of the above-mentioned material, the picture pattern layer 12 and the transparent thermoplastic resin layer 13 are bonded via an adhesive layer (sometimes called an anchor coat layer) 15, as shown in Figure 1.

[0020] The transparent thermoplastic resin layer 13 is not limited to being a single layer as illustrated in Fig. 1, but may be a multi-layer structure, for example, two or more layers. When the transparent thermoplastic resin layer 13 is a multi-layer structure, these multi-layer structures may be the same or different from one another, and the combination of these multi-layer structures is not particularly limited.

[0021] The thickness of the transparent thermoplastic resin layer 13 is not particularly limited, but can be, for example, 30 to 200 μm.

[0022] <Surface protection part> The surface protection portion 20 is a portion that constitutes the outermost surface of the decorative sheet 1, and protects the layers disposed below the surface protection portion 20. The surface protective portion 20 is transparent. Therefore, when the decorative sheet 1 is viewed from the surface protective portion 20 side, the layers disposed below the surface protective portion 20 can be seen. The surface protective portion 20 may be either colorless or colored, as long as it is transparent.

[0023] The surface protection part 20 according to this embodiment is composed of two layers: a first protection layer 21 and a second protection layer 22. The first protection layer 21 is formed on the first surface 13a of the transparent thermoplastic resin layer 13, and the second protection layer 22 is formed on the first protection layer 21. The surface protection section 20 made up of the first protection layer 21 and the second protection layer 22 has an uneven shape following the recesses 131 because the transparent thermoplastic resin layer 13 has the recesses 131 .

[0024] The first protective layer 21 and the second protective layer 22 are both made mainly of a base resin made of a mixture of a curable resin and a curing agent, and a granular low gloss agent. The curable resin may be either a thermosetting resin or an ionizing radiation curable resin. In this specification, "ionizing radiation" means electromagnetic waves or charged particle beams having energy capable of causing a curing reaction of the ionizing radiation curable resin, and specific examples thereof include ultraviolet rays, electron beams, visible light, X-rays, and ion beams.

[0025] Examples of the thermosetting resin include polyfunctional acrylic urethane resin and polyester resin.

[0026] Examples of ionizing radiation curable resins include transparent resins containing as a main component a prepolymer, oligomer, or monomer having in its molecule a radically polymerizable double bond that can undergo a polymerization and crosslinking reaction upon irradiation with ionizing radiation. The above-mentioned prepolymers, oligomers, and monomers may each be of one kind or two or more kinds. When two or more kinds of prepolymers, oligomers, and monomers are used, the combination and ratio thereof can be selected arbitrarily.

[0027] The low-gloss agent is transparent, so that the picture pattern layer 12 remains visible, while diffusely reflecting incident light, thereby reducing the glossiness of the surface of the decorative sheet 1 and imparting a matte appearance. A suitable example of a low-gloss agent is silica particles. The particle size of the silica particles is preferably equal to or smaller than the thickness of the base resin. If the particle size is too large compared to the thickness of the base resin, the stain resistance of the surface of the decorative sheet 1 may be reduced, or the silica particles may be more likely to protrude from the base resin and fall off.

[0028] The pencil hardness of the surface of the surface protection part 20 is 2B or more. The pencil hardness of the surface of the surface protection part 20 in the present invention is the result of measurement by a pencil hardness test in accordance with JIS K5600.

[0029] <Primer layer> The primer layer 16 is a layer for fixing the decorative sheet 1 to the intended application location. By providing the decorative sheet 1 with the primer layer 16, it is possible to omit, for example, the step of primer treating the second surface 11b of the thermoplastic resin base sheet 11 when using the decorative sheet 1. The primer layer 16 is not an essential layer for the decorative sheet and may be omitted.

[0030] The inventors have conducted extensive research into the surface configuration of a decorative sheet that has sufficient scratch resistance and is less likely to crack when folded. As a result, they have succeeded in achieving both by configuring the curing agent of the surface protection portion 20 in a specific manner.

[0031] A commonly used curing agent for the surface protective layer of decorative sheets is a mixture of hexamethylene diisocyanate (HDI) nurate type and xylylene diisocyanate (XDI) (hereinafter sometimes referred to as "curing agent A"), and examples include urethane-based curing agents. Surface protective layers using this curing agent have excellent scratch resistance, but are prone to cracking. Other curing agents include those with longer side chains attached to the six-membered ring than HDI nurate types and that do not contain XDI (hereinafter referred to as "curing agent B"). Examples include urethane-based flexible curing agents. Compared to a mixture of HDI nurate type and XDI, this curing agent has the function of moderately suppressing the shrinkage of the mixture, making it less susceptible to cracking, but at the cost of slightly reduced scratch resistance. Based on this, the inventors conducted various studies and found that by mixing hardener A and hardener B in a 1:1 ratio, it was possible to achieve both sufficient scratch resistance and suppression of cracks during lapping processing.

[0032] Such a mixed curing agent need only be used in the second protective layer 22 of the surface protective section 20, which constitutes the outermost surface of the decorative sheet 1; the curing agent for the underlying first protective layer 21 can be appropriately selected taking into consideration the intended use of the decorative sheet 1, etc. For example, if scratch resistance is more important in the surface protective section 20, only curing agent A may be used, or if a more flexible surface protective section 20 is desired, only curing agent A may be used. Furthermore, a mixture of curing agents A and B in a different ratio than that used in the second protective layer 22 may be used, or a curing agent that is neither curing agent A nor curing agent B may be used. It is of course possible for the curing agent for the first protective layer 21 to be the same as the curing agent for the second protective layer 22.

[0033] Another advantage of the decorative sheet 1 is that it can easily be given a matte appearance. In order to reduce the gloss and impart a suitable matte appearance, it is necessary to incorporate a relatively large amount of a low-gloss agent into the surface protective layer, but if a large amount is incorporated, the low-gloss agent tends to protrude from the base resin, making it more likely to fall off after completion and reducing stain resistance. One way to prevent this is to increase the thickness of the base resin, but this tends to cause poor drying during layer formation, making it difficult to form a suitable layer.

[0034] The surface protective part 20 according to this embodiment has a multi-layer structure including a first protective layer 21 and a second protective layer 22. This allows the surface layer of the decorative sheet to be formed even with a thickness that would cause poor drying if it were a single layer, and by incorporating a sufficient amount of low gloss agent, the gloss level can be easily adjusted to the desired level.

[0035] Another advantage of constructing the surface protective part from multiple layers is that the distribution of the low-gloss agent in the surface protective part can be made non-uniform. That is, even if the first protective layer 21 contains a low-gloss agent to an extent that would reduce stain resistance as a single layer, by setting the content of the low-gloss agent in the covering second protective layer 22 to an appropriate range lower than that of the first protective layer 21, the protrusion of the low-gloss agent on the surface of the entire surface protective part can be suppressed. As a result, a surface protective part can be constructed that maintains stain resistance while containing a low-gloss agent of approximately 15 parts by weight or more per 100 parts by weight of base resin, which is difficult to achieve in a single layer. Meanwhile, because the second protective layer 22 is transparent, the low-gloss agent contained in the underlying first protective layer 21 also diffuses incident light and contributes significantly to reducing gloss.

[0036] With the above configuration, the surface gloss of the surface protection part 20 according to this embodiment is less than 10.0 at 60° and less than 13.0 at 85°. As a result, the decorative sheet 1 according to this embodiment achieves both the effect of suppressing cracks when folded and a good appearance with reduced surface gloss. As a result, it can also be suitably used for flooring materials.

[0037] In this embodiment, the thickness of the base resin of each layer constituting the surface protection part can be set appropriately within a range that does not cause poor drying. An example of such a value is approximately 4 μm to 6 μm. The thicknesses of the multiple layers constituting the surface protection part may be the same or different.

[0038] The decorative sheet according to this embodiment will be described in more detail using examples. The technical scope of the present invention is not limited solely by the specific content of the examples.

[0039] (Example) The thermoplastic resin substrate sheet was a 55 μm thick PE sheet. A urethane-based printing ink was applied to the first side of this sheet to form a pattern layer, and a urethane-based primer was applied to the second side to form a primer layer. Furthermore, a 70 μm thick polypropylene (PP) film was used to form a transparent thermoplastic resin layer on the pattern layer. Thereafter, an embossing roll was used to give the surface an uneven shape.

[0040] Subsequently, a surface protection portion was formed. First, mixture A having the following composition was applied onto a transparent thermoplastic resin layer and dried, and then the base resin was cured by heating to form a first protective layer of base resin having a thickness of 6 μm. <Mixture A> Base resin: 110 parts by mass of a mixture of thermosetting resin, a urethane-based curing agent with a longer side chain attached to the six-membered ring than HDI nurate type, and a mixed curing agent made by mixing HDI nurate type and XDI curing agent in a mass ratio of 1:1 (100 parts by mass of resin, 10 parts by mass of curing agent). Low gloss agent: Silica particles (particle size 2 to 4 μm) 20 parts by weight

[0041] Next, mixture B having the following composition was applied to the transparent thermoplastic resin layer on the first protective layer, dried, and then the base resin was cured by exposure to ionizing radiation to form a second protective layer having a base resin thickness of 6 μm. <Mixture B> Base resin: 110 parts by mass of a mixture of ionizing radiation curing resin and the same mixed curing agent as in mixture A (100 parts by mass of resin, 10 parts by mass of curing agent) Low gloss agent: Silica particles (particle size 2 to 4 μm) 12 parts by weight In this manner, a surface protective part consisting of the first protective layer and the second protective layer was formed, and a decorative sheet according to the example was produced.

[0042] (Comparative Example 1) A decorative sheet according to Comparative Example 1 was produced in the same manner as in the Example, except that the curing agent for Mixtures A and B was a mixture of HDI nurate type and XDI only. (Comparative Example 2) A decorative sheet according to Comparative Example 2 was produced using the same procedure as in the Examples, except that the curing agents in Mixtures A and B were urethane-based curing agents with longer side chains attached to the six-membered ring than the HDI nurate type.

[0043] The decorative sheets according to the examples were evaluated as follows. (wrapping process) For each example, the decorative sheet was wrapped around a board-shaped medium density fiberboard (MDF) and then the decorative sheet was bent at a roughly right angle (90°) and visually inspected to see if there were any cracks. Evaluation was based on the following three levels, with only ○ representing a pass. 〇(Good): No cracks observed △(Bad): Some cracks are observed × (Worse): Cracks are observed throughout the entire surface.

[0044] (Pencil hardness test) The decorative sheet according to each example was attached to MDF and measured in accordance with JIS K 5600. Pencil hardness of 2B or more was considered to be acceptable, and that of 3B or less was considered to be unacceptable. (Hoffman scratch test) The decorative sheet according to each example was attached to MDF, and the surface of each decorative sheet was scratched using a Hoffman scratch hardness tester (manufactured by BYK-Gardner) while increasing the load from 200 g by 100 g. After scratching, the surface of the decorative sheet was checked each time to see if scratches had occurred, and the test was stopped when scratches were found, and the load value at that time was used, with a value of 600 g or more being considered a pass.

[0045] (Stain resistance) The decorative sheet of each example was attached to MDF, and then the test was carried out using black magic marker, red crayon, and blue ink in accordance with the JAS (Japanese Agricultural Standards) special plywood staining test A. The evaluation was made on the following two levels, with only ○ being considered a pass. 〇 (Good): No color residue observed in any case × (Bad): Color remains in at least one area

[0046] (comprehensive evaluation) Among the above items, those that passed all were evaluated as ○ (good), and those that failed any of the items were evaluated as × (bad). The results are shown in Table 1.

[0047] [Table 1]

[0048] In the examples, no cracks were generated during the lapping process, and scratch resistance and contamination resistance were sufficiently ensured. On the other hand, in Comparative Example 1, although there were no problems with scratch resistance or contamination resistance, the occurrence of cracks due to lapping could not be suppressed, and in Comparative Example 2, the occurrence of cracks due to lapping could be suppressed, but the scratch resistance and contamination resistance were insufficient. From the above, the usefulness of the configuration of the decorative sheet according to this embodiment was confirmed.

[0049] The present invention has been described above using embodiments and examples, but the specific configuration is not limited to these embodiments, and configuration changes and combinations within the scope that do not deviate from the gist of the present invention are also included.

[0050] For example, the surface protection part according to the present invention is not limited to the two-layer structure shown in the embodiment, but may be composed of three or more layers. Also, different low gloss agents may be used in each layer. [Explanation of symbols]

[0051] 1 decorative sheet 11 Thermoplastic resin base sheet 12 Pattern layer 13 Transparent thermoplastic resin layer 20 Surface protection part 21 First protective layer 22 Second protective layer

Claims

1. A thermoplastic resin base sheet; a picture pattern layer formed on the thermoplastic resin substrate sheet; a transparent thermoplastic resin layer formed on the picture pattern layer; a surface protection part formed on the transparent thermoplastic resin layer; Equipped with The surface protection part is a first protective layer formed on the transparent thermoplastic resin layer, the first protective layer including a base resin and a low-gloss agent; a second protective layer formed on the first protective layer, the second protective layer including a base resin and a low-gloss agent; The base resin of the second protective layer is composed of a curable resin containing at least one of a thermosetting resin and an ionizing radiation curable resin, and a mixed curing agent obtained by mixing a curing agent obtained by mixing a hexamethylene diisocyanate nurate type curing agent with a xylylene diisocyanate curing agent in a mass ratio of 1:1 with a curing agent having a longer side chain attached to the six-membered ring than that of the hexamethylene diisocyanate nurate type curing agent. Decorative sheet.

2. the thermoplastic resin substrate sheet and the transparent thermoplastic resin layer are made of a polyolefin resin; The decorative sheet according to claim 1 .

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