JP2023161006A - Laminated stretched film, base material for decorative sheet, decorative sheet and decorative plate - Google Patents

Abstract

To provide a laminated stretched film which is reduced in peeling with time between a base material for decorative sheet and a laminate including a base material for decorative sheet and a transparent resin layer provided on an upper layer of a printing layer while having easy peelability with the laminate, a base material for decorative sheet, a decorative sheet and a decorative plate.SOLUTION: A base material 6 is a uniaxially or biaxially laminated stretched film in which a main component of a resin material is made of polypropylene, and has a plurality of layers (number n of layers≥2, n is an integer) in which the main component of the resin material is made of a polypropylene-based resin. When an uppermost layer positioned on the outermost surface among the plurality of layers is defined as a surface layer 6-1, and layers other than the surface layer 6-1 among the plurality of layers are defined as core layers 6-2 to 6-(n-1), the surface layer 6-1 has elastic deformation power of 55% or more and less than 100% in indentation test by Martens hardness tester.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laminated stretched film, a base material for a decorative sheet, a decorative sheet, and a decorative board.

For decorative sheets used for building interior materials and the surfaces of fittings, especially for decorative sheets used in public places, noncombustible materials listed in Article 108-2, Items 1 and 2 of the Enforcement Order of the Building Standards Act are used. It is required to meet the technical standards of Conventionally, decorative sheets containing soft polyvinyl chloride resins have been used as decorative sheets that meet the technical standards for noncombustible materials. However, decorative sheets containing soft polyvinyl chloride resins have a problem in that they generate toxic gas when incinerated after disposal.

Therefore, in recent years, decorative sheets using polyolefin resins instead of polyvinyl chloride resins have been proposed. However, when polyolefin resins are used for decorative sheets, although the generation of toxic gases during combustion is suppressed, the high combustibility of polyolefin resins causes global warming. May be a source of gas.
Examples of decorative sheets using polyolefin resins that meet the technical standards for noncombustible materials listed in the above-mentioned laws and regulations and can suppress the generation of global warming gas include the sheets described in Patent Documents 1 and 2, for example. be. Patent Documents 1 and 2 disclose structures using a polyolefin resin layer containing an inorganic filler such as calcium carbonate.

Japanese Patent Application Publication No. 2013-010931 Japanese Patent Application Publication No. 2011-122293

As mentioned above, with decorative sheets made of polyolefin resin that meet technical standards for non-combustible materials, it is difficult to dramatically reduce the amount of global warming gases generated during production defects and when disposing of used products. be. From the perspective of preventing global warming, it is important to reduce the environmental burden by recycling decorative sheet materials.

When recycling a base material for a decorative sheet, that is, a base material for a decorative sheet, a problem arises in the ease of peeling between the base material for a decorative sheet and the transparent resin layer. In many conventional decorative sheets, the bond between the printed layer and the underlying decorative sheet base material made of polyolefin resin is strong, and the printed layer and the decorative sheet base material are not easily separated. For this reason, it may not be possible to separate the decorative sheet base material from the laminate including the layer above the printed layer. On the other hand, if the interfacial adhesion between the decorative sheet base material and the printed layer is reduced too much, the decorative sheet base material and the printed layer may unintentionally separate during use due to deterioration over time. Problems arose and it was difficult to recycle and use the base material for decorative sheets.

The present invention has been made with attention to the above-mentioned points, and includes easy peelability between a base material for a decorative sheet and a laminate including a transparent resin layer provided above the printing layer. An object of the present invention is to provide a laminated stretched film, a base material for a decorative sheet, a decorative sheet, and a decorative board in which peeling of a base material for a decorative sheet and a laminate thereof over time is reduced.

In order to solve the above problems, a laminated stretched film according to one embodiment of the present invention is a uniaxially or biaxially laminated stretched film, and has a plurality of layers in which the main component of the resin material is a polypropylene resin. , among the plurality of layers, the first layer located on the outermost surface is defined as the surface layer, and the layers other than the surface layer among the plurality of layers are defined as the core layer, and the surface layer is Martens. The gist is that the elastic deformation power is 55% or more and less than 100% in an indentation test using a hardness meter.
Further, a decorative sheet according to one embodiment of the present invention uses the laminated stretched film according to the above one embodiment as a decorative sheet base material, and includes a polyolefin resin formed on the surface layer side of the decorative sheet base material. One or more transparent resin layers.

According to one aspect of the present invention, the base material for a decorative sheet and the laminate thereof can be easily separated from each other, while the base material for a decorative sheet and the laminate including a transparent resin layer provided above the printed layer can be easily separated. Peeling over time can be reduced.
In one aspect of the present invention, cohesive failure of the decorative sheet base material is induced by stretching the decorative sheet base material uniaxially or biaxially and adjusting the elastic deformation power in an indentation test using a Martens hardness meter. It becomes possible to peel off the transparent resin layer along with the printed layer from the decorative sheet base material. In other words, in one aspect of the present invention, by controlling the ease of cohesive failure of the decorative sheet base material without reducing the interfacial adhesive force between the decorative sheet base material and the printed layer, It becomes possible to reduce the peeling force expressed by the peeling test force, that is, to impart easy peelability. In addition, in this embodiment, the above-mentioned "separating the transparent resin layer from the decorative sheet base material together with the printed layer" means that the outermost layer of the decorative sheet base material is attached to the printed layer, and the transparent resin layer is peeled off from the decorative sheet base material together with the printed layer. This includes cases where the outermost layer of the base material also peels off.

In the case of cohesive failure of the base material for decorative sheets, unlike when peeling occurs at the interface between the printed layer and the base material for decorative sheets, deterioration in peel strength (adhesion strength) over time is unlikely to occur. Therefore, by causing cohesive failure of the base material for decorative sheets, it is possible to suppress the deterioration of the peeling force between the printed layer and the base material for decorative sheets over time, and when recycling the decorative sheet, the layers above the printed layer It becomes possible to easily separate the laminate containing the laminate and the decorative sheet base material with low peeling force.
As a method for achieving the above-mentioned easy peelability, the elastic deformation power of the surface layer of the decorative sheet base material in an indentation test using a Martens hardness meter is set to 55% or more and less than 100%. By setting the elastic deformation power in the indentation test using a Martens hardness tester to be 55% or more and less than 100%, cohesive failure is induced in the surface layer, and the laminate including the layers above the printed layer is made into a decorative material. It can be easily peeled off from the sheet base material and can be reused as a decorative sheet base material.

FIG. 1 is a cross-sectional view showing an example of the configuration of a decorative sheet according to an embodiment of the present invention. It is a conceptual diagram showing each area of plastic deformation work and elastic deformation work in elastic deformation power.

An embodiment of the present invention will be described with reference to the drawings.
Here, the configuration shown in FIG. 1 is a schematic one, and the relationship between the thickness and the planar dimension, the ratio of the thickness of each layer, etc. are different from the actual one. In addition, the embodiments shown below illustrate configurations for embodying the technical idea of the present invention, and the technical idea of the present invention is that the materials, shapes, structures, etc. of the component parts are It is not limited to things. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.

FIG. 1 is a sectional view showing the configuration of a decorative sheet 1 according to this embodiment. The decorative sheet 1 has a decorative sheet base material 6 (hereinafter also referred to as the base material 6) made of a laminate including a plurality of thermoplastic resin layers, and on one side (surface) of the base material 6. A printing layer 5, an adhesive layer 4, a transparent resin layer 3, and a surface protection layer 2 are formed in this order. Further, in the decorative sheet 1, a concealing layer 7 and a primer layer 8 are provided on the other surface (back surface) of the base material 6. The back surface of the base material 6 is also called the bottom surface.

The base material 6 consists of a laminate of n base material layers (n is any positive integer of 2 or more). The base material 6 includes a first base layer 6-1 (hereinafter referred to as surface layer 6-1) which is the outermost surface, and a second base layer 6-2 located below the surface layer 6-1. to at least one of the n-th base material layers 6-n. The second base material layer 6-2 to the (n-1)th base material layer 6-(n-1) are referred to as "core layers 6-2 to 6-(n-1)", and The n-th base material layer 6-n, which is the surface, is also referred to as a "lowermost layer 6-n." Further, when the base material 6 is composed of two layers, a surface layer 6-1 and a core layer 6-2, the back surface of the core layer 6-2 becomes the other surface of the base material 6. Furthermore, since the bottom layer 6-n may come into contact with the primer layer 8, it is preferable to have the same structure as the surface layer 6-1. By doing so, the adhesion between the base material 6 and the primer layer 8 can be maintained.

In addition, the hiding layer 7 may be formed between the base material 6 and the printing layer 5, or may be omitted. In particular, in this embodiment, since an inorganic pigment is mixed into the base material 6 as described later, there is no problem in design even if the hiding layer 7 is omitted. When suppressing the amount of pigment mixed into the base material 6, it is preferable to provide a concealing layer 7 as necessary.
The thickness of the decorative sheet 1 is preferably within the range of, for example, 49 μm or more and 360 μm or less. When the thickness of the decorative sheet 1 is within this range, printing workability when manufacturing the decorative sheet 1 is improved, and manufacturing costs can be suppressed.

Such a decorative sheet 1 constitutes a decorative board by attaching the surface (back surface) on the primer layer 8 side to a base plate 9 made of, for example, a wood base material.
Note that the peelability of the decorative sheet 1 was tested in accordance with JIS K 6854-2. In the peel test between the transparent resin layer 3 and the base material 6, the decorative sheet 1 showed that the base material 6 was not deformed or torn, and the transparent resin layer provided above the base material 6 and the printed layer 5 were not deformed or torn. It is preferable to have the ability to separate a laminate containing 3 or the like.
Each part of the decorative sheet 1 will be described in detail below.

<Base material>
The base material 6 of this embodiment is made of a laminated stretched film made into a thin film by uniaxial stretching or biaxial stretching.
By stretching the base material 6, the elastic deformation power in an indentation test using a Martens hardness meter is adjusted, and easy peelability is improved. The thickness of the base material 6 is preferably 20 μm or more and less than 60 μm, more preferably 20 μm or more and 40 μm or less. When the thickness of the base material 6 is in the range of 20 μm or more and less than 60 μm, the decorative sheet 1 can achieve both easy peelability, mechanical properties (mechanical strength), and nonflammability. Moreover, when the thickness of the base material 6 is in the range of 20 μm or more and 40 μm or less, the nonflammability is further improved, which is more preferable.
The reason why the nonflammability is improved by setting the thickness of the base material 6 within the above numerical range is thought to be because the base material 6 becomes thinner by stretching. Furthermore, the reason why the mechanical properties (mechanical strength) are increased by setting the thickness of the base material 6 within the above numerical range is considered to be because the density of the base material 6 is increased by stretching.

The nonflammability of the base material 6 was determined by a heat generation test using a cone calorimeter tester compliant with ISO 5660-1 when it was bonded to a nonflammable base material (not shown) made of a metal plate or an inorganic material. It is preferable that the material is nonflammable enough to satisfy the requirements set forth in Article 108-2, Items 1 and 2 of the Enforcement Order. As in the examples described below, it is possible to impart nonflammability sufficient to satisfy the requirements set forth in Article 108-2, Items 1 and 2 of the Enforcement Order of the Building Standards Act.
As described above, the base material 6 is configured as a laminate of two or more base material layers, and the layers constituting each base material layer are formed of a resin material. The base material 6 contains polypropylene resin, which is a thermoplastic resin, as a main component of the resin material constituting the base material layer. In this specification, the main component refers to, for example, a resin material that is included in 70 parts by mass or more and 100 parts by mass or less, preferably 90 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the resin material constituting the layer. .

(Elastic deformation power and Martens hardness of base material 6)
Hereinafter, "elastic deformation power in an indentation test using a Martens hardness meter" and "Martens hardness" in this embodiment will be explained.
The elastic deformation power in this embodiment is measured using, for example, a Martens hardness measuring device (Fisherscope HM2000; Fisher Instruments Co., Ltd.) based on ISO14577. Further, the elastic deformation power may be measured from a cross section of the base material in order to avoid the influence of the core layer of the laminated base material other than the surface layer during measurement. Specifically, the base material is embedded in a resin such as a cold-curing epoxy resin or a UV-curable resin, sufficiently cured, and then cut to expose a cross section of the base material and subjected to mechanical polishing. The measurement surface may be obtained by In addition, the specific measurement method is to push an indenter into the measurement surface of the base material of each sample, and calculate W _plast (plastic deformation work) and W _elast ( Elastic deformation work) is derived, and elastic deformation power (η _IT ) is derived from the ratio of elastic deformation work to W _total (total deformation work) using the following equations (1) and (2). The measurement conditions are, for example, a test force of 10 mN, a test force loading time of 10 seconds, and a test force holding time of 5 seconds.

Note that FIG. 2 shows each region of W _plast (plastic deformation work) and W _elast (elastic deformation work).
W _total = W _plast + W _elast ... (1)
η _IT =W _elast /W _total ...(2)
Further, the Martens hardness of each layer constituting the base material 6 is determined by, for example, pressing an indenter into the measurement surface of the base material of each sample, and calculating the Martens hardness from the pressing depth and load.

[Surface layer]
The surface layer 6-1 forming the surface of the base material 6 has an elastic deformation power of 55% or more and less than 100% in an indentation test using a Martens hardness meter. By doing so, cohesive failure is induced in the surface layer of the surface layer 6-1, and the base material 6 and the laminate including the layers above the printed layer 5 can be easily separated.
When the elastic deformation power of the surface layer 6-1 is less than 55%, the toughness between the printed layer 5 and the surface layer 6-1 tends to be high. In this case, cohesive failure of the surface layer 6-1 is suppressed and the peel strength is increased, so that easy peelability may be insufficient. On the other hand, if the elastic deformation power of the surface layer 6-1 is 55% or more and less than 100%, the toughness between the printed layer 5 and the surface layer 6-1 decreases, causing agglomeration of the surface layer 6-1. Since destruction is promoted, the peel strength between the printed layer 5 and the surface layer 6-1 decreases, resulting in sufficient easy peelability. Note that the upper limit of the elastic deformation power is 100%.

[Core layer]
When the base material is loaded into a printing machine, the core layers 6-2 to 6-(n-1) are required to have tensile strength due to stretching in order to suppress the occurrence of misalignment of the printing position. Therefore, by setting the elastic deformation power of the core layers 6-2 to 6-(n-1) in an indentation test using a Martens hardness tester to 45% or more and less than 100%, even if the film is thin, the tensile strength is sufficiently high. It becomes the base material. On the other hand, if the elastic deformation power of the core layers 6-2 to 6-(n-1) is less than 45%, the stretched base material may not have sufficient tensile strength.
Furthermore, the Martens hardness values of the core layers 6-2 to 6-(n-1) may be larger than the Martens hardness value of the surface layer 6-1. By making the Martens hardness value of the core layers 6-2 to 6-(n-1) larger than the Martens hardness value of the surface layer 6-1, the peel strength is sufficiently high and the tensile strength is sufficiently high. The base material 6 can have a high value.

[Bottom layer]
It is desirable to separate the decorative sheet 1 from the base plate 9, for example, before peeling the transparent resin layer 3 together with the printed layer 5 from the base material 6. Therefore, the decorative sheet 1 can be easily separated from the base plate 9 by setting the elastic deformation power of the lowermost layer 6-n in an indentation test using a Martens hardness meter to be 55% or more and less than 100%. On the other hand, if the elastic deformation power of the lowermost layer 6-n in the indentation test using the Martens hardness tester is less than 55%, peeling failure due to tearing of the decorative sheet 1 occurs when separating the decorative sheet 1 and the base plate 9. It is more likely to occur.

Furthermore, since the lowermost layer 6-n of the base material 6 may come into contact with the primer layer 8, by making the lowermost layer 6-n of the base material 6 have the same structure as the surface layer 6-1, the base material 6 The adhesion force (adhesion) between the primer layer 8 and the primer layer 8 can also be improved.
As described above, easy peelability can be achieved by specifying the elastic deformation power in the indentation test using a Martens hardness meter for each base material layer of the base material 6. Moreover, in this embodiment, since cohesive failure is induced, it is possible to reduce peeling over time between the base material and the laminate including the transparent resin layer provided above the printing layer.

(resin material)
As mentioned above, the main component of the resin material constituting each base layer constituting the base material 6, that is, the surface layer 6-1 and the core layers 6-2 to 6-n, is polypropylene-based. It is resin.
Examples of the polypropylene resin include those obtained by copolymerizing polypropylene with α-olefin alone or with two or more kinds of α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, tridecene, and 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-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11 Examples include -methyl-1-dodecene and 12-ethyl-1-tetradecene.
In order to improve the tensile modulus of the base material 6, it is preferable to use highly crystalline polypropylene.

(soft material)
The surface layer 6-1 may contain a resin material with low crystallinity as a soft material in order to adjust the elastic deformation power after stretching.
A first example of the soft material is a polypropylene resin made of a propylene-α-olefin copolymer, which is an α-olefin copolymer of polypropylene. A propylene-α-olefin copolymer is a polypropylene resin produced by copolymerizing propylene with an α-olefin consisting of a linear olefin. Examples of α-olefins consisting of linear olefins include ethylene, butene, and pentene. This polypropylene resin made of a propylene-α olefin copolymer has a lower melting point than homopolypropylene.

Here, in a polypropylene resin consisting of a propylene-α olefin copolymer,
The copolymerization ratio of α-olefin is less than 3% or 16% or more (the content of α-olefin is less than 3 parts by mass or 16 parts by mass or more with respect to 100 parts by mass of polypropylene resin, which is a propylene-α-olefin copolymer). It is preferable that
If the copolymerization ratio is 3% or more and less than 16%, the cohesive force of the surface layer 6-1 is high, and there is a possibility that the necessary easy peelability cannot be obtained.

A second example of the soft material is a polypropylene resin whose melting point is lower than that of isotactic homopolypropylene by lowering the stereoregularity of the polypropylene resin. Here, the stereoregularity can be expressed by the mesopentad fraction. The mesopentad fraction representing the stereoregularity of this soft material is preferably less than 30% or 75% or more. If the mesopentad fraction is 30% or more and less than 75%, the surface layer 6-1 has a high cohesive force, and there is a possibility that the necessary easy peelability cannot be obtained.
By appropriately blending the soft materials as exemplified above, the elastic deformation power of the surface layer 6-1 after stretching can be reliably adjusted to 55% or more and less than 100%.

When the surface layer 6-1 includes a soft material, the surface layer 6-1 contains 5 parts or more of the soft material mixed with 100 parts by mass of the main component resin (base resin) constituting the surface layer 6-1. It is preferable to use a mixed resin. When the amount of the soft material mixed is less than 5 parts by mass, the softening effect due to the mixing of the soft material may be difficult to appear. In addition, when the amount of the soft material mixed is 80 parts by mass or more, a softening effect due to the mixing of the soft material appears, but if the heat treatment during stretching of the base material 6 causes a problem of stickiness of the surface layer 6-1. There is.
Furthermore, from the viewpoint of uniformity of the resin material forming the surface layer 6-1, the soft material is preferably a material that is highly compatible with the resin material forming the surface layer 6-1. From this point of view, for example, when the surface layer 6-1 is made of polypropylene resin, it is desirable that the soft material to be mixed is also polypropylene resin.

(Inorganic pigment)
It is preferable that at least one base material layer constituting the base material 6 contains an inorganic pigment. By containing the inorganic pigment, the light transmittance of the base material 6 is reduced, so that the pattern of the base plate 9 to which the decorative sheet 1 is attached cannot be transmitted.
The mixing amount of the inorganic pigment is preferably 5 vol % or more and 50 vol % or less relative to the resin material in the base material layer in which the inorganic pigment is mixed. When the amount of the inorganic pigment mixed is 5 vol% or more and 50 vol% or less, the effect of improving the nonflammability by adding the inorganic pigment is exhibited, and the embrittlement of the base material 6 due to the addition of too much inorganic pigment is also suppressed. This is because it can be done.

The inorganic pigments to be contained are not particularly limited, and include, for example, natural inorganic pigments and synthetic inorganic pigments.
Examples of natural inorganic pigments include earth pigments, fired earth pigments, and mineral pigments. Examples of synthetic inorganic pigments include oxide pigments, hydroxide pigments, sulfide pigments, silicate pigments, phosphate pigments, carbonate pigments, metal powder pigments, and carbon pigments. Furthermore, one or a mixed pigment of two or more of natural inorganic pigments and synthetic inorganic pigments may be used.
Note that it is not preferable to use an organic pigment as the pigment. This is because the nonflammability of the base material 6 is impaired.

The base material 6 preferably has a light transmittance of 40% or less in order to obtain the hiding property required from the viewpoint of the design of the decorative sheet 1. When the light transmittance exceeds 40%, sufficient hiding power to bring out the design of the decorative sheet 1 cannot be obtained. In addition, the above-mentioned "sufficient concealment property" is not obtained, for example, in a decorative board configured by pasting the surface of the decorative sheet 1 on the primer layer 8 side to a base board 9 made of a wood base material or the like. , refers to the fact that the pattern on the surface of the wood base material or the like facing the primer layer 8 is visible from the surface protection layer 2 side through the decorative sheet 1. In such a case, the pattern on the printed layer 5 and the pattern on the base plate 9 made of a wood base material may be visually recognized as overlapping each other. It is preferable to provide a concealing layer 7 in the case of being visually recognized.

<Print layer>
The printed layer 5 is a layer on which a picture pattern is formed to give design properties. The printed layer 5 can be provided on the surface layer 6-1 of the base material 6 using known printing techniques. When the base material 6 can be prepared in a rolled form, printing for forming the printing layer 5 can be performed using a roll-to-roll printing device. The printing method is not particularly limited, but if productivity and quality of the image are taken into consideration, for example, gravure printing can be used.

As for the pattern, any pattern may be adopted in consideration of the design quality depending on the place where the material is used, such as flooring material or wall material. For example, when obtaining a decorative sheet 1 with a wood-based pattern, various wood grain patterns are often preferably used as the pattern, and a cork pattern may also be used in addition to the wood grain pattern. Further, when obtaining a decorative sheet 1 that resembles a floor made of stone such as marble, the pattern of the pattern is the grain of marble. In addition to the patterns of natural materials, artificial patterns such as artificial patterns and geometric patterns based on natural materials as motifs can be used as the pattern of the printing layer 5.
The printing ink used to form the printing layer 5 is not particularly limited, but an ink compatible with the printing method is appropriately selected. In particular, it is preferable that the printing ink is selected in consideration of adhesion to the base material 6, printability, weather resistance of the decorative sheet 1, and the like.

Coloring agents such as pigments and dyes, extender pigments, solvents, and binders contained in ordinary inks are added to the printing ink as appropriate. Examples of the pigment include pearl pigments such as condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, and mica. The binder may be water-based, solvent-based, or emulsion type, and the curing method is particularly limited, such as a one-component type, a two-component type consisting of a main agent and a curing agent, or a type that is cured by ultraviolet rays or electron beams. It's not something you do. Among them, the most common method is a two-component type method that uses a urethane-based main agent and a curing agent consisting of an isocyanate. In addition, designs may be applied by vapor deposition or sputtering of various metals.
The thickness of the printed layer 5 is preferably 2 μm or more and 20 μm or less. When the thickness of the printing layer 5 is within this range, printing can be made clear, printing workability when manufacturing the decorative sheet 1 can be improved, and manufacturing costs can be suppressed.

<Adhesive layer>
The adhesive layer 4 is provided for the purpose of strengthening the adhesion between the base material 6 and the printed layer 5 and the transparent resin layer 3. Due to the strong adhesion between the base material 6 and the printed layer 5 and the transparent resin layer 3, the decorative sheet 1 can be given bending workability that follows a curved surface or a right-angled surface. Adhesive layer 4 is preferably transparent.
The adhesive layer 4 is formed of, for example, an acrylic adhesive, a polyester adhesive, a polyurethane adhesive, an epoxy adhesive, or the like. As the adhesive constituting the adhesive layer 4, it is usually preferable to use a two-component curing type material due to its cohesive strength, particularly a urethane-based material obtained by reaction with a polyol using an isocyanate. Note that the adhesive layer 4 may be omitted if sufficient adhesive strength between the transparent resin layer 3 and the printed layer 5 can be obtained.

Any method can be selected for adhering the transparent resin layer 3 to the base material 6 and print layer 5 via the adhesive layer 4, such as thermal lamination, extrusion lamination, dry lamination, etc. Can be mentioned.
The thickness of the adhesive layer 4 is preferably 1 μm or more and 20 μm or less. When the thickness of the adhesive layer 4 is within this range, the adhesive strength between the base material 6 and the printing layer 5 and the transparent resin layer 3 is improved, and printing workability during production of the decorative sheet 1 is improved. , and manufacturing costs can be suppressed.

<Transparent resin layer>
The transparent resin layer 3 is made of, for example, a transparent resin sheet, and is bonded to the base material 6 and the print layer 5 by an adhesive layer 4. Although the decorative sheet 1 shown in FIG. 1 shows a case in which the transparent resin layer 3 is one layer, a plurality of transparent resin layers 3 may be laminated. The transparent resin layer 3 of this embodiment is preferably composed of polyolefin resin as a main component. The main component refers to, for example, 70 parts by mass or more and 100 parts by mass or less, preferably 90 parts by mass or more and 100 parts by mass or less, of the resin material constituting the transparent resin layer 3 as 100 parts by mass.

In addition to polypropylene, polyethylene, polybutene, etc., the polyolefin resin constituting the transparent resin layer 3 includes, for example, α-olefin (for example, 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-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc.) are homopolymerized or copolymerized with two or more types. Monoya, 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., which are copolymers of ethylene or α-olefin and other monomers. Moreover, when aiming at improving the surface strength of the decorative sheet 1, it is preferable to use highly crystalline polypropylene.

The thickness of the transparent resin layer 3 is preferably 20 μm or more and 200 μm or less. When the thickness of the transparent resin layer 3 is within this range, the strength of the decorative sheet 1 is improved, printing workability when manufacturing the decorative sheet 1 is improved, and manufacturing costs can be suppressed.

<Surface protective layer>
The surface protective layer 2 is provided on the outermost surface of the decorative sheet 1, and has the function of protecting the surface and adjusting the gloss. Examples of materials constituting the surface protective layer 2 include polyurethane resins, acrylic silicone resins, fluorine resins, epoxy resins, vinyl resins, polyester resins, melamine resins, aminoalkyd resins, and urea resins. Examples include. The form of the resin material is not particularly limited, and may be water-based, emulsion, solvent-based, or the like. The curing method can be appropriately selected from one-component type, two-component type, ultraviolet curing method, etc.

In particular, as the resin material that is the main component of the surface protective layer 2, a urethane resin using isocyanate is suitable from the viewpoints of workability, price, cohesive force of the resin itself, and the like. Examples of isocyanates include tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), diphenylmethane diisocyanate (MDI), lysine diisocyanate (LDI), isophorone diisocyanate (IPDI), and methylhexane diisocyanate (HTDI). ), methylcyclohexanone diisocyanate (HXDI), trimethylhexamethylene diisocyanate (TMDI), and the like. Among these, from the viewpoint of weather resistance, hexamethylene diisocyanate (HMDI) having a linear molecular structure is suitable as the isocyanate. In addition, in order to improve the surface hardness, it is preferable to use a resin that is cured by active energy rays such as ultraviolet rays and electron beams. Note that these resins can be used in combination with each other. For example, by using a hybrid type of thermosetting type and photocuring type, it is possible to improve surface hardness, suppress curing shrinkage, and improve adhesion. can be achieved.

The thickness of the surface protective layer 2 is preferably 3 μm or more and 20 μm or less. When the thickness of the surface protective layer 2 is within this range, the surface of the decorative sheet 1 can be protected and it can have sufficient gloss, and the printing workability when manufacturing the decorative sheet 1 can be improved, and the manufacturing cost can be reduced. can be suppressed.

<Hidden layer>
The concealing layer 7 is formed for the purpose of maintaining the concealing property against the base plate 9 in a decorative board in which the surface of the decorative sheet 1 on the primer layer 8 side is pasted on the base plate 9 such as a wood base material. Ru. The concealing layer 7 is formed, for example, by ink printing similarly to the printing layer 5. As the pigment to be included in the ink, it is preferable to use, for example, an opaque pigment, titanium oxide, iron oxide, or the like. Further, in order to improve the hiding ability of the pattern of the base plate 9 made of a wood base material or the like to which the decorative sheet 1 is attached in the hiding layer 7, for example, metals such as gold, silver, copper, and aluminum are added to the ink. However, it is generally preferable to add aluminum flakes. Note that the hiding layer 7 can be omitted if any of the base layers of the base material 6 is opaque and has hiding properties, as described above.
The thickness of the concealing layer 7 is preferably 2 μm or more and 20 μm or less. When the thickness of the concealing layer 7 is within this range, it is possible to maintain the concealing property with respect to the base plate 9, improve printing workability when manufacturing the decorative sheet 1, and suppress manufacturing costs.

<Primer layer>
The primer layer 8 is provided in order to improve the adhesion between the decorative sheet 1 and the base plate 9 in a decorative board in which the surface of the decorative sheet 1 on the primer layer 8 side is attached to the base plate 9.
For the primer layer 8, basically the same material (printing ink) as that for the printing layer 5 can be used. In particular, considering that the decorative sheet 1 will be rolled up in a web form to be applied to the back side, inorganic fillers such as silica, alumina, magnesia, titanium oxide, and barium sulfate may be added to the printing ink. It is preferable to add it. Thereby, it is possible to avoid blocking when winding up the decorative sheet 1 and to improve the adhesion with the adhesive.

When the base plate 9 is a wood base material, the primer layer 8 is made of, for example, ester resin, urethane resin, acrylic resin, polycarbonate resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, It is preferably formed from a resin material such as nitrocellulose resin. These resin materials can be used alone or in combination to form an adhesive composition, which can be formed using an appropriate coating method such as a roll coating method or a gravure printing method. In this case, as the resin material constituting the primer layer 8, it is preferable to use urethane-acrylate resin. That is, it is particularly preferable to use a resin made of a copolymer of an acrylic resin and a urethane resin and an isocyanate.

The thickness of the primer layer 8 is preferably 0.1 μm or more and 20 μm or less. When the thickness of the primer layer 8 is within this range, the adhesion between the decorative sheet 1 and the base plate 9 is improved, and the printing workability when manufacturing the decorative sheet 1 is improved, and the manufacturing process is improved. Costs can be suppressed. Furthermore, when the bottom layer 6-n of the base material 6 has the same material and structure as the surface layer 6-1, the interlayer adhesion between the base material 6 and the primer layer 8 can be improved. Adhesion between the base plate 9 and the base plate 9 can be improved.
The decorative sheet 1 using the base material 6 according to the present embodiment is produced by using a base material formed by stretching and thinning a resin film whose main component is polypropylene resin, which is a thermoplastic resin. This provides easy peelability from the laminate including the transparent resin layer 3 provided above the printing layer 5, while reducing peeling of the laminate from the base material 6 over time.

In addition, the decorative sheet 1 according to the present embodiment has multiple layers of polypropylene resin constituting the stretched film, and the elastic deformation power of the surface layer 6-1 in an indentation test using a Martens hardness meter is 55% or more and 100%. less than
According to this configuration, in this embodiment, cohesive failure can be induced in the surface layer of the surface layer 6-1, so that the base material 6 and the transparent resin layer 3 provided above the printing layer 5, etc. It is possible to reduce peeling between the base material 6 and the laminate over time while providing easy peelability from the laminate containing the base material 6.
That is, according to the present embodiment, the base material 6 and the laminate including the transparent resin layer 3 provided above the printed layer 5 can be easily separated, while the base material 6 and the laminate can be easily separated from each other. A decorative sheet 1 with reduced peeling over time can be obtained.

Furthermore, since the base material 6 can be made thinner by stretching, it is also possible to improve the nonflammability.
Here, when the base material 6 is composed of three or more base material layers, that is, when the core layers 6-2 to 6-n are composed of two or more layers, the bottom layer (nth layer) 6-n is , is preferably made of the same material as the surface layer 6-1. That is, it is preferable that the lowermost layer (nth layer) 6-n has an elastic deformation power of 55% or more and less than 100% in an indentation test using a Martens hardness tester.
According to this configuration, the adhesion between the primer layer 8 and the bottom layer 6-n can be improved.

[Example]
The present invention will be further explained below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<Example 1>
First, Example 1 will be described.
The decorative sheet of Example 1 was formed by the steps shown below.
(Formation process of resin sheet for transparent resin layer)
First, a resin material was prepared by adding a hindered phenol antioxidant, a benzotriazole ultraviolet absorber, and a hindered amine light stabilizer to a homopolypropylene resin. Here, as the homopolypropylene resin, a material with a mesopentad fraction of 97.8%, an MFR (melt flow rate) of 15 g/10 min (230°C), and a molecular weight distribution MWD (Mw/Mn) of 2.3 is used. did. Further, a hindered phenol antioxidant (Irganox 1010: manufactured by BASF) was added at 500 PPM to the homopolypropylene resin. A benzotriazole ultraviolet absorber (Tinuvin 328: manufactured by BASF) was added at 2000 PPM to the homopolypropylene resin. A hindered amine light stabilizer (Kimasorb 944: manufactured by BASF) was added at 2000 PPM to the homopolypropylene resin. Such a resin material was extruded using a melt extruder to form a transparent resin sheet made of polypropylene with a thickness of 80 μm to be used as a transparent resin layer.
Subsequently, both surfaces of the obtained transparent resin sheet were subjected to corona treatment, and the wet tension on the surface of the transparent resin sheet was set to 40 dyn/cm or more.

(Base material formation process)
The base material was composed of three base material layers, the first layer was a surface layer, the second layer was a core layer, and the third layer was a bottom layer. Then, a base material in which the first to third layers were laminated was formed into a film by an extrusion method and stretched. That is, the base material for the decorative sheet was composed of three layers made of polypropylene resin.
A layer serving as a precursor for the first surface layer was formed with a thickness of 12 μm using resin A as a material. Next, on the layer that would become the precursor of the first surface layer, a layer that would become the precursor of the second core layer was formed with a thickness of 108 μm using resin C added with an inorganic pigment as the material. Formed. On top of that, a layer serving as a precursor for the third and lowermost layer was formed using resin C as a material.
Thereby, a laminated resin precursor having a total thickness of three layers of 132 μm was formed.

Next, this laminated resin precursor was stretched 4 times by a uniaxial stretching method to obtain a base material with a thickness of 33 μm (surface layer thickness of 3 μm, core layer thickness of 27 μm, and bottom layer thickness of 3 μm). was formed.
[Resin A]
Resin material: Homo PP (polypropylene)
[Resin C]
Resin material: polypropylene copolymer with 15% ethylene content

(Print layer forming process)
A pattern was printed on the surface layer of the base material using a gravure printing method to form a printed layer. The printing layer is a two-component urethane ink (V180; manufactured by Toyo Ink Mfg. Co., Ltd.) containing 0.5% by mass of a hindered amine light stabilizer (Kimasorb 944; manufactured by BASF) based on the binder resin content of the ink. It was formed using the added ink.

(Transparent resin layer forming process)
Subsequently, a dry laminating adhesive (Takelac A540; manufactured by Mitsui Chemicals, Inc.; coating amount: 2 g/m ² ) was applied as an adhesive layer to the surface layer side of the base material on which the printing layer was formed. Thereafter, a transparent resin sheet was attached to the front surface of the base material on which the printed layer was formed via an adhesive layer by dry lamination to form a transparent resin layer.
In this way, a decorative sheet constituting Example 1 was formed.
In Example 1, the surface layer of the base material had an elastic deformation power (indentation elastic deformation power) of 59, the core layer had an elastic deformation power of 43, and the bottom layer had an elastic deformation power of 43. Ta.

<Example 2>
A decorative sheet constituting Example 2 was formed in the same manner as in Example 1 except that the resin A material described above was used as the material for the bottom layer.
In Example 2, the surface layer of the base material had an elastic deformation power of 59, the core layer had an elastic deformation power of 43, and the bottom layer had an elastic deformation power of 54.

<Example 3>
A decorative sheet constituting Example 3 was formed in the same manner as in Example 1, except that the surface layer, core layer, and bottom layer were each formed using the material of resin A.
In Example 3, the surface layer of the base material had an elastic deformation power of 59, the core layer had an elastic deformation power of 59, and the bottom layer had an elastic deformation power of 54.

<Comparative example 1>
A comparison was made in the same manner as in Example 1, except that the surface layer was formed using the material of resin C, the core layer was formed using the material of resin A, and the bottom layer was formed using the material of resin C. A decorative sheet constituting Example 1 was formed.
In Comparative Example 1, the surface layer of the base material had an elastic deformation power of 44, the core layer had an elastic deformation power of 57, and the bottom layer had an elastic deformation power of 44.

<Comparative example 2>
Same as Example 1 except that the surface layer was formed using the material of Resin B below, the core layer was formed using the material of Resin C, and the bottom layer was formed using the material of Resin B below. A decorative sheet constituting Comparative Example 2 was then formed.
[Resin B]
Resin material: polypropylene copolymer with an ethylene content of 4% In Comparative Example 2, the surface layer of the base material has an elastic deformation power of 50, the core layer has an elastic deformation power of 42, and the bottom layer has an elastic deformation power of 42. The work rate was 50.

Table 1 shows the configurations of each example and each comparative example. Table 1 also describes the evaluation.

<Method for measuring elastic deformation power>
In each Example and each Comparative Example, the elastic deformation power was measured using a Martens hardness meter. Specifically, the elastic deformation power was measured using a Martens hardness measuring device (Fisherscope HM2000; Fisher Instruments Co., Ltd.) based on ISO14577. For the decorative sheets of each Example and each Comparative Example, measurements were taken from the cross section of the base material in order to avoid the influence of the core layer of the laminated base material other than the surface layer. Specifically, the base material is embedded in a resin such as a cold-curing epoxy resin or a UV-curable resin, sufficiently cured, and then cut to expose a cross section of the base material and subjected to mechanical polishing. The measurement surface was obtained by The specific measurement method is to press an indenter into the measurement surface of the base material of each decorative sheet, and calculate Wplast (plastic deformation work) and Welast (elastic deformation work) from the area surrounded by the curve of indentation depth displacement and load. ) was derived, and the elastic deformation power was derived from the ratio of the elastic deformation work to the total deformation work. The measurement conditions were a test force of 10 mN, a test force loading time of 10 seconds, and a test force holding time of 5 seconds.

<Performance evaluation of decorative sheets>
Performance evaluation was performed on the decorative sheets of each Example and each Comparative Example.
[Peelability test (180 degree peel test)]
The peelability test is a test that evaluates the adhesion (adhesion) between the transparent resin layer and the base material as peel strength. The peel test was conducted in accordance with JIS K 6854-2 using the decorative sheets of each Example and each Comparative Example.
The evaluation is as follows.
○: Good (within specifications) (no printed layer remains on the base material for decorative sheet after peeling, peeling force is 3 N/inch or more and less than 12 N/inch)
×: Defective (non-standard) (Printed layer remains on decorative sheet base material after peeling)

As can be seen from the peel test results shown in Table 1, in the decorative sheets of Examples 1 to 3, the laminate including the base material and the transparent resin layer provided above the printed layer deteriorated over time. There was no peeling. Here, the fact that the result of the peel test is good (evaluation of "○") means that easy peelability due to cohesive failure is imparted. This is because in the above peel test, if the printed layer does not remain on the base material for decorative sheets after peeling and peel force is generated, cohesive failure always occurs on the surface layer of the base material. .
As described above, in the decorative sheets of Examples 1 to 3 shown in Table 1, cohesive failure of the base material was induced, and the transparent resin layer, together with the printed layer, could be easily peeled off from the base material.

1 Decorative sheet 2 Surface protection layer 3 Transparent resin layer 4 Adhesive layer 5 Printing layer 6 Base material 6-1 Surface layer (surface base material layer)
6-2 to 6-n Core layer 7 Hiding layer 8 Primer layer 9 Base plate

Claims (7)

A uniaxial or biaxial laminated stretched film having a plurality of layers in which the main component of the resin material is a polypropylene resin,
When the first layer located at the outermost surface of the plurality of layers is defined as the surface layer, and the layers other than the surface layer among the plurality of layers are defined as the core layer,
A laminated stretched film, wherein the surface layer has an elastic deformation power of 55% or more and less than 100% in an indentation test using a Martens hardness tester. The lower layer of the core layer has a lowermost layer in which the main component of the resin material is a polypropylene resin,
The laminated stretched film according to claim 1, wherein the lowermost layer has an elastic deformation power of 55% or more and less than 100% in an indentation test using a Martens hardness tester. 3. The laminated stretched film according to claim 1, wherein the core layer has an elastic deformation power of 45% or more and less than 100% in an indentation test using a Martens hardness tester. A base material for a decorative sheet, comprising the laminated stretched film according to any one of claims 1 to 3. Satisfies the requirements set forth in Article 108-2, Items 1 and 2 of the Building Standards Act Enforcement Ordinance in a heat generation test using a cone calorimeter tester that complies with ISO5660-1 when bonded to a noncombustible base material. The base material for a decorative sheet according to claim 4, wherein the base material is a noncombustible material. The decorative sheet base material according to claim 4 or 5, and one or more transparent resin layers containing a polyolefin resin formed on the surface layer side of the decorative sheet base material. A cosmetic sheet characterized by: A decorative board, characterized in that the decorative sheet according to claim 6 is laminated to a base board made of a wood material.

Images