JP7338151B2 - Base material for decorative sheet, decorative sheet and decorative board - Google Patents

Description

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

For decorative sheets used for building interior materials and surfaces of fittings, especially for decorative sheets used in public places, the noncombustible materials described in Article 108-2, Item 1 and Item 2 of the Enforcement Order of the Building Standards Law It is required to meet the technical standards of Conventionally, a decorative sheet containing a soft polyvinyl chloride resin has been used as a decorative sheet that satisfies the technical standards for such noncombustible materials. However, the decorative sheet containing a soft polyvinyl chloride resin has a problem of generating toxic gas and the like during incineration after disposal.

Therefore, in recent years, decorative sheets using polyolefin-based resins have been proposed instead of polyvinyl chloride-based resins. However, when polyolefin resin is used for decorative sheets, the generation of toxic gases during combustion is suppressed. It was difficult to meet technical standards.
As a decorative sheet using a polyolefin resin that satisfies the technical standards for noncombustible materials described in the above-mentioned laws and regulations, there are sheets described in Patent Documents 1 and 2, for example. The patent documents 1 and 2 disclose a structure using a polyolefin resin layer containing an inorganic filler such as calcium carbonate.

JP 2013-010931 A JP 2011-122293 A

As a method for obtaining a decorative sheet made of a polyolefin resin that satisfies the technical standards for noncombustible materials, for example, there is a method of thinning the base material of the decorative sheet, that is, the base material for the decorative sheet. Further, generally, in order to impart designability to the decorative sheet, a printed layer is provided on the surface of the base material for the decorative sheet. At this time, the decorative sheet base material is required to have sufficient mechanical tensile strength in order to suppress the occurrence of misalignment of the printing position when the decorative sheet base material is loaded into the printing machine.
In this case, if a uniaxially or biaxially stretched stretched film is used as the base material for the decorative sheet, the base material for the decorative sheet can be thinned to increase the non-combustibility of the decorative sheet. By increasing the elastic modulus of , it is possible to increase the mechanical strength of the decorative sheet base material per the same cross-sectional area, and further to increase the mechanical strength of the entire decorative sheet.

However, when the surface layer of the decorative sheet base material is hardened by stretching, stress concentration occurs between the printed layer and the surface layer, and the printed layer and the surface layer are likely to separate in the vicinity of the interface. In such a situation, the peel strength, which is expressed by the peel test force between the base material and the transparent resin layer formed (laminated) on the base material for the decorative sheet via the printed layer, is greatly reduced. There is a problem.
Achieving both improvement in peel strength and improvement in strength by stretching is a problem in obtaining a decorative sheet having both mechanical strength and durability of a thin base material for a decorative sheet.

The present invention was made by paying attention to the above-mentioned points, and can be evaluated by the peel test force between the decorative sheet base material and the laminate including the transparent resin layer provided above the printed layer. To provide a base material for a decorative sheet, a decorative sheet, and a decorative board in which the mechanical strength of the base material for the decorative sheet is improved even though it is a thin film by increasing the elastic modulus while maintaining peel strength (interlaminar adhesion). for the purpose.

In order to solve the above problems, a laminated stretched film according to an aspect 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. , when the first layer located on the outermost surface among the plurality of layers is defined as the surface layer, and the layer other than the surface layer among the plurality of layers is defined as the core layer, the surface layer is Martens The gist is that the hardness is 20 N/mm ² or more and less than 120 N/mm ² and the peak intensity ratio in Raman spectroscopy is 1.0 or more and less than 6.0.
Further, a decorative sheet according to one aspect of the present invention uses the laminated stretched film according to one aspect as a base material for a decorative sheet, and contains a polyolefin-based resin formed on the surface of the base material for the decorative sheet on the surface layer side. and a transparent resin layer of one or more layers.

According to one aspect of the present invention, the peel strength (interlayer adhesion) that can be evaluated by the peel test force between the base material for the decorative sheet and the laminate including the transparent resin layer provided above the printed layer is maintained. At the same time, by increasing the elastic modulus of the decorative sheet base material, it is possible to improve the mechanical strength of the thin film.
In one aspect of the present invention, the base material for decorative sheet is uniaxially or biaxially stretched to adjust the Martens hardness and the peak intensity ratio of the surface layer of the base material for decorative sheet in Raman spectroscopy. , stress concentration at the interface between the surface layer and the core layer is suppressed, and sufficient peel strength is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows one structural example of the decorative sheet which concerns on embodiment of this invention.

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 relation between the thickness and the planar dimension, the ratio of the thickness of each layer, and the like are different from the actual one. Further, the embodiments shown below are examples of configurations for embodying the technical idea of the present invention. It is not limited to things. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

FIG. 1 is a cross-sectional view showing the configuration of a decorative sheet 1 according to this embodiment. The decorative sheet 1 has a base material 6 for a decorative sheet (hereinafter also referred to as base material 6) composed of a laminate including a plurality of thermoplastic resin layers, and on one side (surface) of the base material 6 In addition, a printed layer 5, an adhesive layer 4, a transparent resin layer 3 and a surface protective layer 2 are formed in this order. In addition, the decorative sheet 1 is provided with a masking layer 7 and a primer layer 8 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 substrate 6 is composed of a laminate of n (n is any positive integer equal to or greater than 2) substrate layers. The base material 6 includes a first base material layer 6-1 (hereinafter referred to as the surface layer 6-1) which is the outermost surface, and a second base material layer 6-2 which is located below the surface layer 6-1. and at least one of the n-th base layers 6-n. The second base layer 6-2 to the (n-1)th base layer 6-(n-1) are "core layers 6-2 to 6-(n-1)", and the other base layer 6-(n-1) The n-th base layer 6-n, which is the surface, is also referred to as the "bottom layer 6-n". Further, when the substrate 6 is composed of two layers, the surface layer 6-1 and the core layer 6-2, the back surface of the core layer 6-2 is the other surface of the substrate 6. FIG. Since the bottom layer 6-n may be in contact with the primer layer 8, it preferably has 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.

The concealing layer 7 may be formed between the base material 6 and the printed layer 5, or may be omitted. In particular, in this embodiment, as will be described later, an inorganic pigment is mixed into the base material 6, so there is no problem in terms of design even if the masking layer 7 is omitted. In order to reduce the amount of pigment mixed with the base material 6, it is preferable to provide the masking layer 7 as necessary.
The thickness of the decorative sheet 1 is preferably in 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, the printing workability when manufacturing the decorative sheet 1 is improved, and the manufacturing cost can be suppressed.
Such a decorative sheet 1 constitutes a decorative board by attaching the surface (back surface) of the decorative sheet 1 on the side of the primer layer 8 to a base plate 9 made of, for example, a woody base material.
Each part of the decorative sheet 1 will be described in detail below.

<Base material>
The substrate 6 of the present embodiment is made of a laminated stretched film thinned by uniaxial stretching or biaxial stretching.
By stretching the base material 6, the Martens hardness and the peak intensity ratio of the surface layer of the decorative sheet base material in Raman spectroscopy are adjusted, and the peel strength (interlayer adhesion) that can be evaluated by the peel test force is improved. are doing. The thickness of the base material 6 is preferably 20 μm or more and less than 60 μm, and 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 peel strength, mechanical properties (mechanical strength), and noncombustibility of the decorative sheet 1 can be compatible. 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.

It is considered that the reason why nonflammability is enhanced by setting the thickness of the base material 6 within the above numerical range is that the base material 6 is thinned by stretching. Further, the reason why the mechanical properties (mechanical strength) are enhanced by setting the thickness of the base material 6 within the above numerical range is considered to be that the elastic modulus of the base material 6 is increased by stretching.
The noncombustibility of the base material 6 is evaluated by a heat generation test using a cone calorimeter tester in accordance with ISO 5660-1 in a state where it is laminated with a noncombustible base material (not shown) made of a metal plate or an inorganic material. It is preferable to have incombustibility sufficient to satisfy the requirements described in Article 108-2, Item 1 and Item 2 of the Enforcement Order. It is possible to impart incombustibility sufficient to satisfy the requirements described in Article 108-2, Item 1 and Item 2 of the Enforcement Ordinance of the Building Standards Act, as in the examples described later.

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-based resin, which is a thermoplastic resin, as a main component of the resin material forming the base material layer. In this specification, the main component is, 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 that constitutes the layer is 100 parts by mass. .

(Martens hardness of base material 6)
The “Martens hardness” in this embodiment will be described below.
The Martens hardness in the present embodiment is measured using, for example, a Martens hardness measuring device (Fischerscope HM2000; Fisher Instruments Co., Ltd.) conforming to ISO14577. In addition, Martens hardness may be measured from the cross section of the substrate in order to avoid the influence of the core layer of the laminated substrate other than the surface layer during measurement. Specifically, the base material is embedded in a resin such as a cold-curing type epoxy resin or UV-curing resin, which is sufficiently hardened, and then cut so that the cross section of the base material appears, followed by mechanical polishing. A measurement plane may be obtained by A specific measuring method is to press an indenter against the measuring surface of the base material of each sample, and calculate the Martens hardness from the depth of the pressing and the load. The measurement conditions are, for example, a test force of 10 mN, a test force load required time of 10 seconds, and a test force holding time of 5 seconds.

(Peak intensity ratio of substrate 6 in Raman spectroscopy)
The “peak intensity ratio in Raman spectroscopy” in this embodiment will be described below.
In this embodiment, a polarizing filter is used to analyze Raman scattered light in order to measure the peak intensity ratio of the polypropylene film surface by Raman spectroscopy. Here, the value of the peak intensity ratio is represented by the following formula (1).

The S808 parallel and the S841 parallel are the peak intensity at 808 cm ^{−1 and the peak intensity at 841 cm −1 when} the polarization direction and the MD direction (flow direction during film formation) are parallel. S808 vertical is the peak intensity at 808 cm ⁻¹ when the polarization direction is perpendicular to the MD direction, and S841 vertical is the peak intensity at 841 cm ⁻¹ when the polarization direction is perpendicular to the MD direction. This peak intensity ratio serves as a measure of the degree of molecular orientation.

[Surface layer]
The surface layer 6-1 forming the surface of the base material 6 has a Martens hardness of 20 N/mm ² or more and less than 120 N/mm ² , preferably 50 N/mm ² or more and less than 120 N/mm ² , and Raman spectroscopy. The peak intensity ratio at is 1.0 or more and less than 6.0. By doing so, stress concentration between the printed layer 5 and the surface layer 6-1 can be suppressed, resulting in sufficient peel strength. Further, if the Martens hardness of the surface layer 6-1 is 50 N/mm ² or more, the stretched film can be made preferable in terms of scratch resistance on the surface. If the Martens hardness is less than 20 N/mm ² , stress concentration occurs between the surface layer 6-1 and the core layers 6-2 to 6-(n-1), resulting in insufficient peel strength. . If the Martens hardness is 120 N/mm ² or more, stress concentration may occur between the printed layer 5 and the surface layer 6-1, resulting in insufficient peel strength.

Even if the Martens hardness of the surface layer 6-1 is 20 N/mm ² or more and less than 120 N/mm ² , if the peak intensity ratio in Raman spectroscopy is 6.0 or more, the surface layer 6- 1, the cohesive failure of the surface layer 6-1 may occur in the peel test between the transparent resin layer 3 and the substrate 6, resulting in insufficient peel strength. Further, when the peak intensity ratio in Raman spectroscopy is less than 1.0, the cohesive force of the surface layer 6-1 is insufficient. -1 cohesive failure may occur and peel strength may be insufficient. On the other hand, by setting the peak intensity ratio in Raman spectroscopy to 1.0 or more and less than 6.0, the peel strength between the transparent resin layer 3 and the substrate 6 becomes sufficient.
Thus, by setting the Martens hardness of the surface layer 6-1 to 20 N/mm ² or more and less than 120 N/mm ² and the peak intensity ratio in Raman spectroscopy to 1.0 or more and less than 6.0, The peel strength between the stretched base material 6 and the transparent resin layer 3 can be improved.

[Core layer]
The substrate is required to have sufficient mechanical tensile strength in order to suppress the occurrence of misalignment of the printing position when the substrate is loaded into the printing machine. Therefore, by setting the Martens hardness of the core layers 6-2 to 6-(n-1) to 60 N/mm ² or more and less than 150 N/mm ² , the base material has sufficiently high tensile strength even if it is a thin film. . On the other hand, if the Martens hardness of the core layers 6-2 to 6-(n-1) is less than 60 N/mm ² , the stretched and thinned substrate may not have sufficient tensile strength. Further, if the Martens hardness is 150 N/mm ² or more, stress concentration occurs between the surface layer 6-1 and the core layers 6-2 to 6-(n−1), which is not preferable.
Further, the Martens hardness value of the core layers 6-2 to 6-(n−1) may be greater 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, both the peel strength and the tensile strength of the base material 6 are sufficiently high. can be

[Bottom layer]
When recycling the decorative sheet 1, it is desirable to separate the decorative sheet 1 from the base plate 9, for example. Therefore, by setting the Martens hardness of the bottom layer 6-n to 20 N/mm ² or more and less than 120 N/mm ² and the peak intensity ratio in Raman spectroscopy to 1.0 or more and less than 6.0, the decorative sheet 1 can be easily separated from the base plate 9 . On the other hand, if the bottom layer 6-n has a Martens hardness of less than 20 N/mm ² or more than 120 N/mm ² , the decorative sheet 1 may not be easily separated from the base plate 9 . Moreover, even if the peak intensity ratio in Raman spectroscopy is less than 1.0 or 6.0 or more, the decorative sheet 1 may not be easily separated from the base plate 9 in some cases.

Further, since the bottom layer 6-n of the base material 6 may be in contact with the primer layer 8, by configuring the bottom layer 6-n of the base material 6 to have the same structure as the surface layer 6-1, the base material 6 and the adhesion (adhesion) between the primer layer 8 and the primer layer 8 can also be improved.
As described above, by defining the Martens hardness and the peak intensity ratio in Raman spectroscopy in the surface layer 6-1 of the base material 6, the base material 6 and the transparent resin layer provided above the printed layer 5 3 and the like can be improved in peel strength (interlayer adhesion) that can be evaluated by a peel test force, and the mechanical strength of the thinned base material 6 can be improved.

(resin material)
As described above, the main component of the resin material constituting each base material layer constituting the base material 6, that is, each base layer forming the surface layer 6-1 and the core layers 6-2 to 6-n is polypropylene-based. Resin.
Examples of polypropylene-based resins include those obtained by copolymerizing polypropylene with α-olefin alone or with two or more kinds thereof. Examples of α-olefins 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 -methyl-1-dodecene, 12-ethyl-1-tetradecene and the like.
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 Martens hardness after stretching or the peak intensity ratio in Raman spectroscopy.
A first example of the soft material is a polypropylene-based resin composed of a propylene-α-olefin copolymer, which is an α-olefin copolymer of polypropylene. A propylene-α-olefin copolymer is a polypropylene-based resin produced by copolymerizing propylene with an α-olefin consisting of a linear olefin. Examples of α-olefins composed of linear olefins include ethylene, butene, and pentene. The polypropylene-based resin composed of this propylene-α-olefin copolymer is a polypropylene-based resin having a lower melting point than that of homopolypropylene.

Here, the copolymerization ratio of the α-olefin in the polypropylene-based resin made of the propylene-α-olefin copolymer is 3% or more and less than 16% (per 100 parts by mass of the polypropylene-based resin that is the propylene-α-olefin copolymer, The α-olefin content is preferably 3 parts by mass or more and less than 16 parts by mass).
If the copolymerization ratio is 16% or more, the cohesive force of the surface layer 6-1 is lowered, and the necessary peel strength may not be obtained. Also, if the copolymerization ratio is less than 3%, the surface layer 6-1 may have a reduced cohesive strength, and the required peel strength may not be obtained.

A second example of the soft material is a polypropylene-based resin that has a lower melting point than isotactic homopolypropylene by lowering the stereoregularity of the polypropylene-based resin. Here, the stereoregularity can be expressed by the mesopentad fraction. It is desirable that the mesopentad fraction representing the stereoregularity of the soft material is 30% or more and less than 75%. If the mesopentad fraction is less than 30%, the cohesive force of the surface layer 6-1 is lowered, and the necessary peel strength may not be obtained. Further, when the mesopentad fraction is 75% or more, the cohesive force of the surface layer 6-1 is lowered, and the necessary peel strength may not be obtained.
By appropriately blending the soft materials as exemplified above, it is possible to ensure that the surface layer 6-1 after stretching has a Martens hardness of 20 N/mm ² or more and less than 120 N/mm ² and a peak intensity in Raman spectroscopy. The ratio can be adjusted from 1.0 to less than 6.0.

When the surface layer 6-1 contains a soft material, the surface layer 6-1 is formed by mixing 5 parts by mass or more of the soft material with 100 parts by mass of the main component resin (base resin) constituting the surface layer 6-1. It is preferably made of a mixed resin. If the mixed amount of the soft material is less than 5 parts by mass, the softening effect due to the mixing of the soft material may be difficult to appear. When the mixed amount of the soft material is 80 parts by mass or more, the softening effect due to the mixing of the soft material appears, but the stickiness of the surface layer 6-1 may become a problem due to the heat treatment during stretching of the base material 6. There is
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 a polypropylene-based resin, it is desirable that the soft material to be mixed is also a polypropylene-based resin.

(Inorganic pigment)
At least one base material layer constituting the base material 6 preferably contains an inorganic pigment. By containing the inorganic pigment, the light transmittance of the base material 6 is lowered so that the pattern of the base plate 9 to which the decorative sheet 1 is adhered can be prevented from being transmitted.
The mixing amount of the inorganic pigment is preferably 5 vol % or more and 50 vol % or less with respect to the resin material in the base layer containing the inorganic pigment. When the mixing amount of the inorganic pigment is 5 vol% or more and 50 vol% or less, the effect of improving the nonflammability due to the addition of the inorganic pigment is exhibited, and embrittlement of the base material 6 due to the addition amount of the inorganic pigment being too large is also suppressed. This is because

The inorganic pigment to be contained is not particularly limited, but examples thereof include natural inorganic pigments and synthetic inorganic pigments.
Examples of natural inorganic pigments include earth pigments, calcined earth, 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. Also, one or a mixture of two or more of natural inorganic pigments and synthetic inorganic pigments may be used.
In addition, it is not preferable to use an organic pigment as the pigment. This is because the nonflammability of the substrate 6 is impaired.

The base material 6 preferably has a light transmittance of 40% or less in order to obtain the concealing property required from the viewpoint of the design of the decorative sheet 1 . If the light transmittance is more than 40%, the decorative sheet 1 cannot have sufficient concealing properties to bring out the design. In addition, the above-mentioned "sufficient hiding property cannot be obtained" means, for example, in a decorative board configured by attaching the surface of the decorative sheet 1 on the primer layer 8 side to a base board 9 made of a wooden base material or the like. , means that the pattern on the surface of the wood substrate or the like facing the primer layer 8 is visible from the side of the surface protective layer 2 through the decorative sheet 1 . When visible in this way, the design of the printed layer 5 and the pattern of the substrate plate 9 such as a wooden substrate may be visually recognized overlapping. It is preferable to provide the concealing layer 7 when it is visible.

<Print layer>
The printed layer 5 is a layer on which a pattern is formed in order to impart design properties. The printed layer 5 can be provided on the surface layer 6-1 of the substrate 6 using a known printing technique. If the substrate 6 can be prepared in a rolled state, printing for forming the printing layer 5 can be performed by a roll-to-roll printing apparatus. The printing method is not particularly limited, but if productivity and image quality are taken into consideration, gravure printing, for example, can be used.

As for the pattern, any pattern may be adopted in consideration of the design properties according to the place of use such as the floor material and the wall material. For example, when obtaining a decorative sheet 1 having a wood-based pattern, various wood grain patterns are often preferred for the pattern, and a cork pattern may be used in addition to the wood grain pattern. In addition, when obtaining the decorative sheet 1 having an image of a stone floor such as marble, the grain of marble or the like is used for the picture pattern. In addition to the picture patterns of natural materials, artificial picture patterns such as geometric patterns and artificial patterns using natural materials as motifs are used as the picture patterns of the printed layer 5 .
The printing ink used to form the printing layer 5 is not particularly limited, but an ink corresponding to the printing method is appropriately selected. In particular, it is preferable to select the printing ink in consideration of adhesion to the substrate 6, printability, weather resistance of the decorative sheet 1, and the like.

Coloring agents such as pigments and dyes, extender pigments, solvents, and binders, which are contained in ordinary inks, are appropriately added to the printing ink. Examples of pigments include condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, and pearl pigments such as mica. The binder may be water-based, solvent-based, or emulsion type, and the curing method is also particularly limited, such as a one-liquid type, a two-liquid type consisting of a main agent and a curing agent, or a type that is cured by ultraviolet rays, electron beams, or the like. not something to do. Among them, the general method is a two-liquid type method using a urethane-based main agent and an isocyanate curing agent. In addition, the design 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 printed layer 5 is within this range, the print can be clearly printed, the printing workability in manufacturing the decorative sheet 1 can be improved, and the manufacturing cost 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 . Strong adhesion between the base material 6 and the printed layer 5 and the transparent resin layer 3 makes it possible to give the decorative sheet 1 bending workability to follow curved surfaces and perpendicular surfaces. Adhesive layer 4 is preferably transparent.
The adhesive layer 4 is made 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 urethane-based material obtained by reaction with a polyol using isocyanate as a two-liquid curing type because of its cohesion. Note that the adhesive layer 4 may be omitted if sufficient adhesive strength is obtained between the transparent resin layer 3 and the printed layer 5 .

Any method can be selected as a method for bonding the substrate 6 and the printed layer 5 to the transparent resin layer 3 via the adhesive layer 4. For example, a lamination method such as thermal lamination, extrusion lamination, or dry lamination can be used. 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 printed layer 5 and the transparent resin layer 3 is improved, and the printing workability during the production of the decorative sheet 1 is improved. , and the manufacturing cost can be suppressed.

<Transparent resin layer>
The transparent resin layer 3 is composed of, for example, a transparent resin sheet, and is adhered to the base material 6 and the printed layer 5 with an adhesive layer 4 . In the decorative sheet 1 shown in FIG. 1, the case where the transparent resin layer 3 is one layer is illustrated, but a plurality of transparent resin layers 3 may be laminated. The transparent resin layer 3 of this embodiment is preferably composed mainly of a polyolefin resin. The main component is, for example, 70 to 100 parts by mass, preferably 90 to 100 parts by mass of the resin material that constitutes the transparent resin layer 3 is 100 parts by mass.

Examples of polyolefin-based resins constituting the transparent resin layer 3 include polypropylene, polyethylene, polybutene, and α-olefins (eg, 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 kinds. 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 copolymers, ethylene-butyl acrylate copolymers, and the like, copolymers of ethylene or α-olefins with other monomers. In order to improve 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, the printing workability in manufacturing the decorative sheet 1 is improved, and the manufacturing cost can be suppressed.

<Surface protective layer>
The surface protective layer 2 is provided on the outermost surface of the decorative sheet 1 and has functions of surface protection and gloss adjustment. Materials constituting the surface protective layer 2 include, for example, polyurethane-based resins, acrylic silicon-based resins, fluorine-based resins, epoxy-based resins, vinyl-based resins, polyester-based resins, melamine-based resins, aminoalkyd-based resins, and urea-based resins. etc. The form of the resin material is not particularly limited, and may be water-based, emulsion, solvent-based, or the like. As for the curing method, a one-liquid type, a two-liquid type, an ultraviolet curing method, or the like can be appropriately selected and carried out.

In particular, as the resin material that is the main component of the surface protective layer 2, a urethane-based resin using isocyanate is suitable from the viewpoints of workability, cost, cohesion of the resin itself, and the like. Isocyanates include, for example, tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), diphenylmethane diisocyanate (MDI), lysine diisocyanate (LDI), isophorone diisocyanate (IPDI), methylhexane diisocyanate (HTDI). ), methylcyclohexanone diisocyanate (HXDI), trimethylhexamethylene diisocyanate (TMDI), and the like. Among them, hexamethylene diisocyanate (HMDI) having a linear molecular structure is suitable as the isocyanate from the viewpoint of weather resistance. 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. These resins can be used in combination with each other. For example, by using a hybrid type of thermosetting type and photosetting type, it is possible to improve surface hardness, suppress curing shrinkage, and improve adhesion. can be planned.

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, it is possible to protect the surface of the decorative sheet 1 and to provide sufficient luster, improve the printing workability when manufacturing the decorative sheet 1, and reduce the manufacturing cost. can be suppressed.

<Concealing layer>
The concealing layer 7 is formed for the purpose of maintaining the concealability with respect to the base plate 9 in the decorative board in which the primer layer 8 side surface of the decorative sheet 1 is attached to the base board 9 such as a wooden base. be. The masking layer 7 is formed, for example, by ink printing in the same manner as the printed 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. In addition, in order to improve the concealability of the pattern of the base plate 9 made of a wooden base material or the like to which the decorative sheet 1 is attached in the concealing layer 7, for example, a metal such as gold, silver, copper, or aluminum is added to the ink. It is also possible to add aluminum flakes, and it is generally preferable to add aluminum flakes. As described above, the concealing layer 7 can be omitted when any one of the substrate layers of the substrate 6 is opaque and has concealing properties.
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 concealability with respect to the base plate 9, improve printing workability when manufacturing the decorative sheet 1, and reduce manufacturing costs.

<Primer layer>
The primer layer 8 is provided to improve adhesion between the decorative sheet 1 and the base plate 9 in the decorative plate in which the primer layer 8 side of the decorative sheet 1 is attached to the base plate 9 .
The primer layer 8 can basically use the same material (printing ink) as the printing layer 5 . In particular, considering that the decorative sheet 1 is wound in a web shape because it is applied to the back surface, inorganic fillers such as silica, alumina, magnesia, titanium oxide, and barium sulfate are added to the printing ink. It is preferable to add This makes it possible to avoid the occurrence of blocking when the decorative sheet 1 is wound up, and to enhance the close contact with the adhesive.

When the substrate plate 9 is a wood substrate, the primer layer 8 is made of, for example, an ester resin, a urethane resin, an acrylic resin, a polycarbonate resin, a vinyl chloride-vinyl acetate copolymer, a polyvinyl butyral resin, It is preferably made of a resin material such as nitrocellulose resin. These resin materials can be used alone or mixed to form an adhesive composition, which can be formed using an appropriate coating means such as a roll coating method or a gravure printing method. In this case, it is preferable to use a urethane-acrylate resin as the resin material forming the primer layer 8 . That is, it is particularly preferable to use a resin composed 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 adhesiveness between the decorative sheet 1 and the base plate 9 is improved, and the printing workability when manufacturing the decorative sheet 1 is improved. Cost 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 with the base plate 9 can be improved.
The decorative sheet 1 using the base material 6 according to the present embodiment uses a base material formed by stretching and thinning a resin film mainly composed of polypropylene-based resin, which is a thermoplastic resin, so that the base material 6 And, while maintaining the peel strength (interlayer adhesion) that can be evaluated by the peel test force with the laminate including the transparent resin layer 3 provided above the printed layer 5, the mechanical properties of the thinned base material 6 improving strength.

In addition, the decorative sheet 1 according to the present embodiment has multiple layers of polypropylene-based resin constituting the stretched film, and the surface layer 6-1 has a Martens hardness of 20 N/mm ² or more and less than 120 N/mm ² , and , the peak intensity ratio in Raman spectroscopy is 1.0 or more and less than 6.0.
According to this configuration, in the present embodiment, the peel strength (interlayer adhesion) between the substrate 6 and the laminate including the transparent resin layer 3 provided above the printed layer 5 can be evaluated by the peel test force. By increasing the elastic modulus of the base material 6 while maintaining the above, it is possible to improve the mechanical strength of the thin film.
That is, according to the present embodiment, the peel strength (interlayer adhesion) that can be evaluated by the peel test force between the substrate 6 and the laminate including the transparent resin layer 3 provided above the printed layer 5 is maintained. At the same time, by increasing the elastic modulus of the base material 6, it is possible to obtain the decorative sheet 1 having improved mechanical strength despite being a thin film.

Furthermore, since the base material 6 can be thinned by stretching, it is also possible to improve 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 two or more layers, the lowest layer (nth layer) 6-n is , is preferably made of the same material as the surface layer 6-1. That is, the lowest layer (nth layer) 6-n has a Martens hardness of 20 N/mm ² or more and less than 120 N/mm ² and a peak intensity ratio in Raman spectroscopy of 1.0 or more and less than 6.0. is preferred.
This configuration can improve the adhesion between the primer layer 8 and the lowermost layer 6-n.

[Example]
The present invention will be further described 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.
(Step of forming resin sheet for transparent resin layer)
First, a resin material was prepared by adding a hindered phenol-based antioxidant, a benzotriazole-based ultraviolet absorber, and a hindered amine-based light stabilizer to a homopolypropylene resin. Here, as the homopolypropylene resin, a material having 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. A hindered phenol-based antioxidant (Irganox 1010: manufactured by BASF) was added at 500 ppm to the homopolypropylene resin. A benzotriazole-based 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 polypropylene transparent resin sheet having 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 to adjust the wetting tension of the surface of the transparent resin sheet to 40 dyn/cm or more.

(Base material forming step)
A structure was adopted in which the substrate was composed of three substrate layers, the first layer being the surface layer, the second layer being the core layer, and the third layer being the bottom layer. Then, a base material in which three layers of the first to third layers were laminated was formed by extruding and stretching the film. That is, the decorative sheet base material was composed of three layers made of a polypropylene-based resin.
A layer serving as a precursor of the surface layer of the first layer was formed with a thickness of 12 μm using the resin A as a material. Subsequently, on the layer that will be the precursor of the surface layer of the first layer, a layer that will be the precursor of the core layer of the second layer is formed with a thickness of 108 μm using resin C to which an inorganic pigment is added as a material. formed. A layer serving as a precursor of the third layer was laminated thereon using the resin B as a material.
Thereby, a laminated resin precursor having a total thickness of 132 μm of three layers was formed.

Subsequently, this laminated resin precursor was stretched 4 times by a uniaxial stretching method to obtain a substrate having a thickness of 33 μm (thickness of the surface layer 3 μm, thickness of the core layer 27 μm, thickness of the bottom layer 3 μm). formed.
[Resin A]
Resin material: random PP (polypropylene)
[Resin B]
Resin material: homo PP (polypropylene)
[Resin C]
Resin material: Polypropylene copolymer with an ethylene content of 4%

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

(Transparent resin layer forming step)
Subsequently, an adhesive for dry lamination (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 substrate on which the printed layer was formed. Thereafter, a transparent resin layer was formed by laminating a transparent resin sheet to the front surface of the base material on which the printed layer was formed via an adhesive layer by a dry lamination method.
Thus, a decorative sheet constituting Example 1 was formed.
In Example 1, the surface layer of the substrate has a Martens hardness of 110 and a peak intensity ratio in Raman spectroscopy of 5.5, and the core layer has a Martens hardness of 52 and a peak intensity ratio in Raman spectroscopy of The bottom layer had a Martens hardness of 159 and a peak intensity ratio of 6.1 in Raman spectroscopy.

<Example 2>
A decorative sheet constituting Example 2 was formed in the same manner as in Example 1, except that the material of resin A was used as the material for the lowermost layer.
In Example 2, the surface layer of the substrate has a Martens hardness of 110 and a peak intensity ratio in Raman spectroscopy of 5.5, and the core layer has a Martens hardness of 52 and a peak intensity ratio in Raman spectroscopy of The bottom layer had a Martens hardness of 109 and a Raman spectroscopy peak intensity ratio of 5.3.

<Example 3>
The procedure of Example 1 was repeated except that the above resin A material was used as the surface layer material, the above resin B material was used as the core layer material, and the above resin A material was used as the bottom layer material. Thus, a decorative sheet constituting Example 3 was formed.
In Example 3, the surface layer of the substrate has a Martens hardness of 110 and a peak intensity ratio in Raman spectroscopy of 5.5, and the core layer has a Martens hardness of 96 and a peak intensity ratio in Raman spectroscopy of The bottom layer had a Martens hardness of 109 and a peak intensity ratio of 5.3 in Raman spectroscopy.

<Example 4>
The procedure of Example 1 was repeated except that the above resin C material was used as the surface layer material, the above resin B material was used as the core layer material, and the above resin C material was used as the bottom layer material. Thus, a decorative sheet constituting Example 4 was formed.
In Example 4, the surface layer of the substrate has a Martens hardness of 54 and a peak intensity ratio in Raman spectroscopy of 1.9, and the core layer has a Martens hardness of 103 and a peak intensity ratio in Raman spectroscopy of The bottom layer had a Martens hardness of 54 and a peak intensity ratio of 2.1 in Raman spectroscopy.

<Example 5>
The same procedure as in Example 1 was carried out except that the above resin C material was used as the surface layer material, the above resin C material was used as the core layer material, and the above resin C material was used as the bottom layer material. Thus, a decorative sheet constituting Example 5 was formed.
In Example 5, the surface layer of the substrate has a Martens hardness of 56 and a peak intensity ratio in Raman spectroscopy of 1.9, and the core layer has a Martens hardness of 52 and a peak intensity ratio in Raman spectroscopy of The bottom layer had a Martens hardness of 55 and a peak intensity ratio of 1.7 in Raman spectroscopy.

<Comparative Example 1>
The procedure of Example 1 was repeated except that the above resin B material was used as the surface layer material, the above resin B material was used as the core layer material, and the above resin B material was used as the bottom layer material. Thus, a decorative sheet constituting Comparative Example 1 was formed.
In Comparative Example 1, the surface layer of the substrate had a Martens hardness of 160 and a peak intensity ratio in Raman spectroscopy of 6.2, and the core layer had a Martens hardness of 92 and a peak intensity ratio in Raman spectroscopy of The bottom layer had a Martens hardness of 159 and a peak intensity ratio of 6.1 in Raman spectroscopy.

<Comparative Example 2>
The procedure of Example 1 was repeated except that the following resin D material was used as the surface layer material, the above resin B material was used as the core layer material, and the following resin D material was used as the bottom layer material. Thus, a decorative sheet constituting Comparative Example 2 was formed.
[Resin D]
Resin material: Polypropylene copolymer with an ethylene content of 15% In Comparative Example 2, the surface layer of the substrate has a Martens hardness of 16 and a peak intensity ratio in Raman spectroscopy of 1.8, and the core layer has a Martens hardness The bottom layer had a Martens hardness of 18 and a peak intensity ratio of 1.7 by Raman spectroscopy.

<Comparative Example 3>
The procedure of Example 1 was repeated except that the above resin B material was used as the surface layer material, the above resin C material was used as the core layer material, and the above resin B material was used as the bottom layer material. Thus, a decorative sheet constituting Comparative Example 3 was formed.
In Comparative Example 3, the surface layer of the substrate had a Martens hardness of 160 and a peak intensity ratio in Raman spectroscopy of 6.5, and the core layer had a Martens hardness of 58 and a peak intensity ratio in Raman spectroscopy of 2, and the bottom layer had a Martens hardness of 161 and a peak intensity ratio of 6.7 in Raman spectroscopy.

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

<Method for measuring Martens hardness>
In each example and each comparative example, Martens hardness was measured using a Martens hardness tester. Specifically, the Martens hardness was measured using a Martens hardness measuring device (Fischerscope HM2000; Fisher Instruments Co., Ltd.) conforming to ISO14577. For the decorative sheets of each example and each comparative example, measurement was performed from the cross section of the substrate in order to avoid the influence of the core layer of the laminated substrate other than the surface layer during measurement. Specifically, the base material is embedded in a resin such as a cold-curing type epoxy resin or UV-curing resin, which is sufficiently hardened, and then cut so that the cross section of the base material appears, followed by mechanical polishing. A measurement surface was obtained by As a specific measuring method, an indenter was pushed into the measuring surface of the base material of each decorative sheet, and the Martens hardness was calculated from the indentation depth and the load. In addition, the measurement was performed under the conditions of a test force of 10 mN, a required test force load time of 10 seconds, and a test force holding time of 5 seconds.

<Method for measuring peak intensity ratio in Raman spectroscopy>
In each example and each comparative example, the peak intensity ratio of the polypropylene film surface was measured by Raman spectroscopy. Specifically, Raman scattered light was analyzed using a polarizing filter. Here, the value of the peak intensity ratio is represented by the following equation (2).

The S808 parallel and the S841 parallel were defined as the peak intensity at 808 cm ⁻¹ and the peak intensity at 841 cm ⁻¹ when the polarization direction and the MD direction (flow direction during film formation) were parallel. The S808 vertical is the peak intensity at 808 cm ⁻¹ when the polarization direction is perpendicular to the MD direction, and the S841 vertical is the peak intensity at 841 cm ⁻¹ when the polarization direction is perpendicular to the MD direction.

<Performance evaluation of decorative sheet>
Performance evaluation was performed on the decorative sheets of each example and each comparative example.
[Peel test (180 degree peel test)]
The peel test (180-degree peel test) is a test for evaluating the adhesion (adhesion) between the transparent resin layer and the substrate as peel strength. The peel test was conducted according to JIS K 6854-2 using the decorative sheets of each example and each comparative example.
Evaluation is as follows.
○: Good (within the standard) (12 N / inch or more)
×: Poor (out of standard) (peel force less than 12 N/inch)

[Elastic modulus measurement (tensile test)]
The decorative sheet of each example and each comparative example was pulled at 50 mm/min by a Tensilon universal material testing machine to measure the elastic modulus.
Evaluation of elastic modulus is as follows.
○: Very good (elastic modulus of 800 MPa or more)
△: good (modulus of elasticity of 500 MPa or more and less than 800 MPa)
×: Poor (elastic modulus less than 500 MPa)

As can be seen from the results of the peel test shown in Table 1, in the decorative sheets of Examples 1 to 5, the peel test between the substrate and the laminate containing the transparent resin layer provided above the printed layer The peel strength (interlayer adhesive strength) that can be evaluated by force was sufficient.
Further, as shown in Table 1, the decorative sheets of Examples 1 to 5 had a sufficient elastic modulus.

1 decorative sheet 2 surface protective layer 3 transparent resin layer 4 adhesive layer 5 printed layer 6 substrate 6-1 surface layer (surface substrate layer)
6-2 to 6-n Core layer 7 Concealing layer 8 Primer layer 9 Base plate

Claims (6)

A decorative sheet base material comprising a uniaxially or biaxially laminated stretched film,
The laminated stretched film has a plurality of layers in which the main component of the resin material is a polypropylene resin,
When the first layer located on the outermost surface among 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,
The surface layer has a Martens hardness of 20 N/mm ² or more and less than 120 N/mm ² and a peak intensity ratio in Raman spectroscopy of 1.0 or more and less than 6.0,
The laminated stretched film has a lowermost layer whose main component of the resin material is a polypropylene-based resin under the core layer,
The bottom layer has a Martens hardness of 20 N/mm ² or more and less than 120 N/mm ² and a peak intensity ratio in Raman spectroscopy of 1.0 or more and less than 6.0 ,
A base material for a decorative sheet , wherein the surface layer and the bottom layer are made of materials having the same composition . The surface layer has a Martens hardness of 50 N/mm ² or more and less than 120 N/mm ² ,
The base material for a decorative sheet according to claim 1, wherein the core layer has a Martens hardness of 60 N/mm ² or more and less than 150 N/mm ² . 3. The base material for a decorative sheet according to claim 1, wherein the Martens hardness value of the core layer is greater than the Martens hardness value of the surface layer. Satisfies the requirements described in Article 108-2 No. 1 and No. 2 of the Enforcement Order of the Building Standards Law in the exothermic test with a cone calorimeter tester conforming to ISO 5660-1 in a state where it is laminated with a noncombustible base material. 4. The base material for a decorative sheet according to any one of claims 1 to 3, which is a noncombustible material. A single or multiple layers of transparent resin containing the base material for decorative sheet according to any one of claims 1 to 4, and a polyolefin resin formed on the surface layer side of the base material for decorative sheet. A decorative sheet comprising: a layer; A decorative board comprising the decorative sheet according to claim 5 and a substrate board made of a wood material.

Images