JP2021063165A - White sheet, decorative sheet and manufacturing method thereof - Google Patents

Abstract

To provide a white sheet having an excellent concealment properties without increasing an addition amount of an inorganic pigment compared with a prior art, a decorative sheet having the white sheet as a substrate layer and manufacturing method of these decorative sheets.SOLUTION: In a white sheet 2, reflection chromaticity measured at a D65 light source is such that, in an Lab color system, L* is within a range of 90 to 100, a* is within a range of -1.5 to +1.5, and b* is within a range of -1.5 to 2.0, and spectral reflectance has a minimum value within a range of 500nm to 650nm.SELECTED DRAWING: Figure 7

Description

The present invention relates to a white sheet, a decorative sheet, and a method for producing the same.

In recent years, many decorative sheets using olefin resins (for example, polypropylene sheets) have been proposed as decorative sheets to replace polyvinyl chloride decorative sheets, which are concerned about environmental protection problems. As a technique relating to a decorative sheet using an olefin resin, for example, there is a technique described in Patent Document 1. By not using vinyl chloride resin in these decorative sheets, the generation of toxic gas and the like during incineration is suppressed. However, in general, polypropylene sheets have problems such as poor scratch resistance due to their low elastic modulus and easy elongation when tension is applied to the sheets during sheet production such as printing.

By the way, a decorative sheet is attached to the surface of a substrate such as a wood substrate, a metal substrate, or a non-combustible substrate to form a decorative board, and the decorative sheet imparts a design property to the decorative board according to the purpose. Therefore, the decorative sheet needs to be covered so that the surface of the substrate is completely invisible, if necessary. In this case, it is necessary to use a decorative sheet that is at least colored with a pigment and has concealing properties. The simplest configuration of the decorative sheet includes a configuration of only a base material layer composed of a single colored sheet (single layer). In the case of a decorative sheet consisting of only such a base material layer, the design that can be applied is usually limited to a single color without a pattern, but for example, by adding a bright material such as aluminum flakes or pearl pigment as a pigment, it shines. Since it is possible to give a feeling, it is possible to express the necessary and sufficient design. Further, when it is desired to give a higher design, it is also effective to decorate the surface of the base material layer by printing or the like.

Among the decorative sheets, the white sheet is used for door frames, timbers, various storages, etc. The surface of the base material of the white sheet can be easily seen through, and it is necessary to add a large amount of pigment in order to impart concealment. However, there is a problem that the white sheet as a whole becomes hard and easily broken by adding a large amount of pigment. Patent Document 2 proposes a decorative sheet in which an inorganic pigment is blended in a vesicled state and has excellent hiding power even when the amount of the pigment added increases, but the increase in the amount of the pigment added is avoided. This was not possible, and the problem of fragility was not solved.

Japanese Patent No. 3271022 Japanese Unexamined Patent Publication No. 2016-155233

The present invention has been made by paying attention to the above points, and a white sheet or a white sheet having good hiding property is used as a base material layer without increasing the amount of the inorganic pigment added as compared with the prior art. It is an object of the present invention to provide a decorative sheet or a method for producing the decorative sheet.

The present inventors have repeated various studies and experiments, and for example, by adding titanium oxide and at least one kind of blue pigment to the resin, the hiding property having a minimum value of spectral reflectance in the range of 500 nm or more and 650 nm or less. It has been found that an excellent white sheet, a decorative sheet and a method for producing the same can be provided.

In order to achieve the object, in the white sheet according to one aspect of the present invention, the reflectance chromaticity measured by the D65 light source is in the range of 90 or more and 100 or less in L * in the Lab color system, and a * is −. A white sheet having a range of 1.5 or more and +1.5 or less and a b * of -1.5 or more and 2.0 or less, and having a spectral reflectance within a range of 500 nm or more and 650 nm or less. The gist is to have a minimum value.

According to one aspect of the present invention, since it is not necessary to increase the amount of the inorganic pigment added as compared with the prior art, a white sheet, a decorative sheet and a decorative sheet which are excellent in flexibility such as bending workability and excellent concealing property. The manufacturing method can be provided.

It is sectional drawing which shows the structure of the decorative sheet which concerns on embodiment of this invention. It is sectional drawing which shows the structure of another decorative sheet which concerns on embodiment of this invention. It is sectional drawing which shows the structure of another decorative sheet which concerns on embodiment of this invention. It is a graph which shows the spectral reflectance of the white sheet containing only titanium oxide. It is a graph which shows the spectral reflectance of a sheet containing cobalt blue and ultramarine blue as a blue pigment, respectively. It is a graph which shows the spectral reflectance measured by the same white sheet on a white background and a black background, respectively. It is a graph which shows the spectral reflectance of Examples 1 to 4 and Comparative Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Here, the drawings are schematic, and the relationship between the thickness and the plane dimension, the ratio of the thickness of each layer, and the like are different from the actual ones. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, structure, etc. of the constituent parts as follows. It is not something that is specific to something. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.

"Constitution"
The decorative sheet 1 of the embodiment shown in FIG. 1 is an example in the case of a single-layer structure of only the white sheet 2. Further, as shown in FIG. 2, the white sheet 2 of the present embodiment is formed on at least one surface of a colored layer 3 formed by mixing an inorganic pigment with a polypropylene resin and a colored layer 3, and is made of a polypropylene resin. It may be composed of the layer 4. The skin layer 4 is intended to prevent the inorganic pigment contained in the colored layer 3 from bleeding and adhering to the manufacturing equipment in the manufacturing process, resulting in poor film formation. The skin layer 4 may contain a nano-sized nucleating agent in order to improve the crystallinity. By improving the crystallinity, the scratch resistance is improved. In the present embodiment, the nucleating agent may be contained, for example, in the form of a vesicle of the nucleating agent contained in the outer membrane.

If necessary, the pattern layer 5 may be formed (laminated) on one surface of the white sheet 2 to improve the design. Further, in the decorative sheet 1, at least one layer of the transparent resin layer 6 and the top coat layer 7 may be laminated on one surface side of the white sheet 2. The decorative sheet 1 illustrated in FIG. 3 is an example in which the pattern layer 5, the transparent resin layer 6, and the top coat layer 7 are laminated in this order on one surface of the white sheet 2. Further, one of the transparent resin layer 6 and the top coat layer 7 may be omitted. Further, the pattern layer 5 may be omitted.

Here, at least one of the transparent resin layer 6 and the top coat layer 7 may be provided with an embossed uneven pattern (embossed pattern 6a) depending on the requirements for design. Ink can be embedded in the embossed pattern 6a to further improve the design. Further, if there is a problem in the adhesion between the pattern layer 5 and the transparent resin layer 6, the adhesive resin layer 6b may be provided as appropriate. When the adhesive resin layer 6b is provided, it is formed by a coextrusion method of the transparent resin layer 6 and the adhesive resin layer 6b. The adhesive resin layer 6b may be formed of, for example, a resin such as polypropylene, polyethylene, or acrylic that has been acid-modified. The thickness of the adhesive resin layer 6b is preferably 2 μm or more for the purpose of improving the adhesive strength. Further, from the requirement of scratch resistance and the like, it is possible to stack a plurality of layers of at least one of the transparent resin layer 6 and the top coat layer 7, and another known layer may be arranged.

In FIGS. 1, 2 and 3, reference numeral B represents a substrate. The substrate B is a substrate to which the decorative sheet 1 is attached. The substrate B is not particularly limited, and examples thereof include wood boards, inorganic boards, metal plates, and composite boards made of a plurality of materials. A primer layer 8 or a concealing layer (not shown) may be appropriately provided between the decorative sheet 1 and the substrate B.

The range of the tensile elastic modulus of the decorative sheet 1 of the present embodiment, particularly the tensile elastic modulus of the white sheet 2 alone, is preferably 1000 MPa or more and 2200 MPa or less. When the tensile elastic modulus is less than 1000 MPa, the scratch resistance tends to deteriorate. When the tensile elastic modulus exceeds 2200 MPa, the crystallinity is too high, and even when a nucleating agent (for example, a nucleating agent vesicle) is used, problems such as whitening and cracking may occur in the bending process.

Next, each layer constituting the decorative sheet 1 will be described.

<White sheet 2>
The white sheet 2 has a reflection chromaticity measured by a D65 light source in a Lab color system, L * in the range of 90 or more and 100 or less, and a * in the range of −1.5 or more and +1.5 or less. , B * is formed so as to be in the range of −1.5 or more and 2.0 or less, and the spectral reflectance is formed so as to have a minimum value in the range of 500 nm or more and 650 nm or less. For example, it has a colored layer 3 formed by mixing an inorganic pigment with a resin in an appropriate composition. If the colored layer 3 is on the outermost layer, the pigment component contained in the colored layer 3 may bleed, and the T-die of the extruder, the roll during transportation, or the like may be contaminated. It is desirable to provide 4. When the skin layer 4 is thin, the pigment component contained in the colored layer 3 bleeds, so that the thickness of the skin layer 4 is preferably 3 μm or more. The skin layer 4 may be formed on at least one surface of the colored layer 3.

The thickness of the white sheet 2 is preferably in the range of 50 μm or more and 150 μm or less. When the thickness of the white sheet 2 is less than 50 μm, the performance (non-landing property) of covering the unevenness of the base is poor, which is not preferable. On the other hand, if the thickness of the white sheet 2 exceeds 150 μm, problems such as whitening and cracking may occur in the bending process.

(Inorganic pigment)
The inorganic pigment contains, for example, titanium oxide in order to impart concealing properties to the white sheet 2. The white sheet 2 plays a role of concealing the pattern of the base material B. In order to obtain the concealing property required from the viewpoint of the design of the decorative sheet 1, the light transmittance is preferably 40% or less. If the hiding property is low, the patterns of the pattern layer 5 and the base material B are mixed, which is not preferable. By containing an inorganic pigment, a decorative sheet 1 having a good hiding property can be obtained. The mixing amount (addition amount) of the entire inorganic pigment is preferably in the range of 5 parts by mass or more and 70 parts by mass or less with the resin material as 100 parts by mass. If the mixing amount is less than 5 parts by mass, the hiding property is poor, and if the mixing amount is more than 70 parts by mass, embrittlement of the white sheet 2 occurs, which is not preferable.

FIG. 4 shows a graph of the spectral reflectance of the white sheet containing only titanium oxide. The spectral reflectance is low on the short wavelength side, but the reflectance is 90% or more in the wavelength range of 450 nm to 700 nm.
The white sheet 2 contains at least one kind of blue pigment as an inorganic pigment in addition to the above-mentioned titanium oxide.

As a blue pigment, a beautiful blue-purple pigment powdered with lapis lazuli (lapis lazuli) has been used since ancient times. It was called ultramarine because it was brought from beyond the distant sea. It can now be synthesized and is known as Gunjo. Ultramarine can be made by mixing, for example, the clay mineral kaolin with sulfur, activated carbon, etc. and baking it. The three-dimensional aluminosilicate lattice that constitutes ultramarine contains three sulfur atoms that are bonded to form ions. The blue color of the pigment is due to the radical anion having unpaired electrons, and its drawback is that it is weak against acids. In addition, in ultramarine, for example, there is a complex of sodium silicate containing sulfur (Na _8-10 Al ₆ Si ₆ O ₂₄ S _2-4 ).

Prussian blue is the first synthetic pigment born in Germany, also known as Prussian blue, and cobalt blue is also a bright blue pigment. In addition, inorganic pigments such as cerulean blue and Kuresu can be used. Prussian blue (Millory blue) is, for example, a pigment represented by the composition formula of _{Fe 4} [Fe (CN) ₆ ] _3. Further, cobalt blue is, for example, a pigment represented by a composition formula of _{CoAl 2} O ₄ or CoO Al ₂ O _3. Further, cerulean blue is, for example, _{a pigment represented by a composition formula of CoO · nSnO 2} · mMgO (n = 1.5 to 3.5, m = 2 to 6). Kuresu is, for example, quartz, halloysite, or lysiophorite.

FIG. 5 shows a graph of the spectral reflectance of a sheet containing cobalt blue and ultramarine independently as blue pigments. Although there are differences in reflectance depending on the type of blue pigment, qualitatively, the blue pigment exhibits a spectral reflectance having a minimum value in the range of 500 nm to 650 nm.
The amount of the blue pigment added is preferably in the range of 1 part by mass or more and 2 parts by mass or less when titanium oxide is 100 parts by mass. If the amount of the blue pigment added is less than 1 part by mass, it is difficult to obtain the effect of improving the hiding power, and if the amount of the blue pigment added is more than 2 parts by mass, the bluish tint is strong and it cannot be recognized as white.

As the inorganic pigment contained in the white sheet 2, a known inorganic pigment can be mixed and used in addition to the above-mentioned titanium oxide and blue pigment. The inorganic pigment to be mixed is not particularly limited, and examples thereof include natural inorganic pigments and synthetic inorganic pigments. Examples of natural inorganic pigments include earth-based pigments, calcined soil, and mineral pigments. Examples of synthetic inorganic pigments include oxide pigments, hydroxide pigments, sulfide pigments, silicate pigments, phosphate pigments, carbonate pigments, metal powder pigments, carbon pigments and the like. In addition, organic pigments such as phthalocyanine and carbon black may be used in combination.

By containing titanium oxide and at least one kind of blue pigment in an appropriate blending ratio, the white sheet 2 can obtain a spectral reflectance having a minimum value in the range of 500 nm or more and 650 nm or less. The superiority or inferiority of the hiding property is judged by the color difference when the base is white or black, but as shown in FIG. 6, the spectral reflectance shows a difference on the long wavelength side of 500 nm or more. Therefore, if the spectral reflectance on the long wavelength side is reduced with a blue pigment in advance, a sheet having good hiding properties can be obtained.

(resin)
The resin to be mixed with the inorganic pigment is preferably an olefin resin from the viewpoint of environmental protection. Examples of the olefin resin include olefin homopolymers such as ethylene, propylene and butene, block copolymers of ethylene-propylene, random copolymers, at least one of ethylene and propylene, and at least one of butene, pentene and hexene. Examples thereof include a polymer of one kind with another olefin, a polymer of at least one of ethylene and propylene, and a polymer of at least one other monomer such as vinyl acetate and vinyl alcohol. Of these, polyethylene and polypropylene are preferable from the viewpoint of obtaining excellent scratch resistance and good bending workability.

[Polyethylene resin]
Polyethylene may be a homopolymer of ethylene, or other comonomer copolymerizable with ethylene and ethylene (eg, α-olefins such as propylene, 1-butene, 1-hexene, 1-octene, vinyl acetate, etc. It may be a copolymer with (vinyl alcohol, etc.). Examples of the polyethylene resin include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (VLDPE), and ultra-high-density polyethylene (Ultra-high-density polyethylene). UHMWPE), crosslinked polyethylene (PEX) and the like. These polyethylenes may be used alone or in combination of two or more.

[Polypropylene resin]
Highly crystalline polypropylene, which will be described later, is preferably used as the polypropylene resin, but for example, a random polypropylene resin having ethylene content within a predetermined range or a known amorphous polypropylene resin is mixed with the highly crystalline homopolypropylene. be able to.
In the present embodiment, it is preferable to use a polypropylene resin having high crystallinity as the polypropylene resin. In particular, the highly crystalline homopolypropylene resin, which is a propylene homopolymer having an isotactic pentad fraction (mmmm fraction) of 95% or more, is in the range of 50% by mass or more and 100% by mass or less with respect to the mass of the total polypropylene resin. It is preferable to use it inside.

The crystallization temperature of the polypropylene resin is generally in the range of 100 ° C. to 130 ° C., and is in the range of 110 ° C. to 140 ° C. when a nucleating agent is added. Further, when a polypropylene resin having an isotactic pentad fraction (mmmm fraction) of less than 95% is used, the crystallinity is insufficient, so that the tensile elastic modulus is lower than the preferable range even if the manufacturing process is controlled. It may become. Further, when the amount of the highly crystalline homopolypropylene resin is less than 50% by mass, the crystallinity is also insufficient, so that the tensile elastic modulus may be lower than the preferable range even if the manufacturing process is controlled.

Here, the isotactic pentad fraction (mmmm fraction) refers to a resin material having a predetermined resonance frequency by a 13C-NMR measurement method (nuclear magnetic resonance measurement method) using carbon C (nuclear species) having a mass of 13. It is calculated from the numerical value (electromagnetic wave absorption rate) obtained by resonating with the above, and defines the atomic arrangement, electronic structure, and molecular fine structure in the resin material. The pentad fraction of the crystalline polypropylene resin is the ratio of five propylene units determined by 13C-NMR arranged side by side, and is used as a measure of crystallinity or stereoregularity. The pentad fraction is one of the important factors that mainly determine the scratch resistance of the surface, and basically, the higher the pentad fraction, the higher the crystallinity.

When a base material having an inert surface, which is formed of a resin such as an olefin resin, is used for the decorative sheet 1, the front and back surfaces of the white sheet 2, for example, corona treatment, plasma treatment, ozone treatment, electron beam treatment, etc. It is desirable to perform UV treatment, heavy chromium acid treatment, etc.
Further, an additive such as a fatty acid metal salt may be added to a resin such as a polypropylene resin in order to improve dispersibility and extrusion suitability.

<Pattern layer 5>
On the surface of the white sheet 2, a pattern layer 5 for adding a pattern to the decorative sheet 1 can be provided. As the pattern, for example, a wood grain pattern, a stone grain pattern, a sand grain pattern, a tiled pattern, a brickwork pattern, a cloth grain pattern, a leather squeezing pattern, a geometric figure, or the like can be used.
Further, a solid base ink layer (not shown) may be provided between the white sheet 2 and the pattern layer 5 according to the degree of the target design. The base solid ink layer is provided so as to cover the entire surface of the white sheet 2, for example. Further, the base solid ink layer may be a multi-layer having two or more layers, if necessary, such as hiding property. Further, the pattern layer 5 may be formed by laminating as many plates as necessary to express the required design. As described above, the pattern layer 5 and the base solid ink layer have various combinations depending on the required design, that is, the design to be expressed, but are not particularly limited.

The constituent materials of the base solid ink layer and the pattern layer 5 are not particularly limited. As a constituent material of the base solid ink layer and the pattern layer 5, for example, a printing ink or a coating agent obtained by dissolving and dispersing a matrix and a colorant such as a dye or a pigment in a solvent can be used. Examples of the matrix include oil-based vitrified cotton resin, two-component urethane resin, acrylic resin, styrene resin, polyester resin, urethane resin, polyvinyl resin, alkyd resin, epoxy resin, melamine resin, and fluorine resin. Various synthetic resins such as resins, silicone-based resins, and rubber-based resins, or mixtures thereof, copolymers, and the like can be used. Examples of colorants include inorganic pigments such as carbon black, titanium white, zinc flower, petals, chrome yellow, navy blue, and cadmium red, azo pigments, lake pigments, anthraquinone pigments, phthalocyanine pigments, and isoindolinone pigments. , Organic pigments such as dioxazine pigments, or mixtures thereof. As the solvent, for example, toluene, xylene, ethyl acetate, butyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, water, etc., or a mixture thereof can be used. ..

Further, in order to impart various functions to the base solid ink layer and the pattern layer 5, for example, an extender pigment, a plasticizer, a dispersant, a surfactant, a tackifier, an adhesive aid, a desiccant, a curing agent, and a curing agent. Functional additives such as accelerators and curing retarders may be added.
Here, the base solid ink layer and the pattern layer 5 can be formed by various printing methods such as a gravure printing method, an offset printing method, a screen printing method, an electrostatic printing method, and an inkjet printing method. Further, since the base solid ink layer covers the entire surface of the white sheet 2, it can be formed by various coating methods such as a roll coating method, a knife coating method, a microgravure coating method, and a die coating method. These printing methods and coating methods may be selected separately depending on the layer to be formed, but it is efficient to select the same method and perform batch processing.
The thickness of the pattern layer 5 is preferably in the range of 3 μm or more and 20 μm or less. When the thickness of the pattern layer 5 is within this range, printing can be clarified, printing workability when manufacturing the decorative sheet 1 can be improved, and manufacturing cost can be suppressed.

<Transparent resin layer 6>
The resin material used as the main component of the transparent resin layer 6 is preferably made of an olefin resin, and in addition to polypropylene, polyethylene, polybutene and the like, α-olefins (for example, propylene, 1-butene, 1-pentene, 1) -Hexen, 1-heptene, 1-octene, 1-nonen, 1-decene, 1-ethylene, 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.) alone Copolymerized or copolymerized with two or more types, ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl methacrylate copolymer, ethylene / butyl methacrylate Examples thereof include those obtained by copolymerizing ethylene or α-olefin with other monomers, such as a polymer, an ethylene / methyl acrylate copolymer, an ethylene / ethyl acrylate copolymer, and an ethylene / butyl acrylate copolymer. .. Further, when improving the surface strength of the decorative sheet 1, it is preferable to use highly crystalline polypropylene.
Here, in the present embodiment, the main component refers to 90% by mass or more of the target material unless otherwise specified.

When the transparent resin layer 6 is provided, the layer thickness of the transparent resin layer 6 is preferably in the range of 50 μm or more and 100 μm or less. When the layer thickness of the transparent resin layer 6 is less than 50 μm, the effect of improving the scratch resistance on the surface of the transparent resin layer 6 is low, and the significance of providing the transparent resin layer 6 is reduced. Further, when the layer thickness of the transparent resin layer 6 exceeds 100 μm, the rigidity of the decorative sheet 1 is too high, and there is a possibility that problems such as whitening and cracking may occur in the bending process.
However, when the top coat layer 7 is provided on the transparent resin layer 6, the layer thickness of the transparent resin layer 6 may be less than 50 μm.

The resin composition constituting the transparent resin layer 6 may contain, for example, a heat stabilizer, a light stabilizer, an antiblocking agent, a catalyst scavenger, a colorant, a light scattering agent, a gloss adjusting agent, etc., if necessary. Various functional additives of the above may be contained. These various functional additives can be appropriately selected and used from well-known ones.

Further, the adhesive used for adhering the pattern layer 5 and the transparent resin layer 6 can be arbitrarily selected as an adhesive method, and for example, there are laminating methods such as thermal laminating, extrusion laminating, and dry laminating. The adhesive can be selected from, for example, acrylic, polyester, polyurethane, and other materials. Usually, a two-component curing type urethane-based material utilizing the reaction between isocyanate and polyol is desirable because of its cohesive force. Although there are no particular restrictions on the laminating method, a method applying heat pressure, an extrusion laminating method, a dry laminating method, or the like is common. Further, when embossing the pattern 6a, there are a method of later embossing the sheet once laminated by various methods by heat pressure, and a method of providing an uneven pattern on the cooling roll and embossing at the same time as extrusion laminating.

Further, a method of laminating the embossed pattern layer 5 and the transparent resin layer 6 at the same time as extrusion by heat or dry lamination can be used.
Further, when further laminating strength is required by the extrusion laminating method, an adhesive resin layer 6b may be provided between the transparent resin layer 6 and the adhesive. When the adhesive resin layer 6b is provided, the transparent resin layer 6 and the adhesive resin layer 6b are laminated by a coextrusion method. The adhesive resin layer 6b may be formed of, for example, a resin such as polypropylene, polyethylene, or acrylic that has been acid-modified. The thickness of the adhesive resin layer 6b is preferably 2 μm or more for the purpose of improving the adhesive strength.

<Top coat layer 7>
When it is necessary to further improve the scratch resistance and adjust the gloss, the top coat layer 7 can be provided on the surface of the transparent resin layer 6.
The resin material as the main component of the top coat layer 7 is appropriately selected from, for example, polyurethane-based, acrylic silicon-based, fluorine-based, epoxy-based, vinyl-based, polyester-based, melamine-based, aminoalkyd-based, and urea-based resin materials. Can be used. The form of the resin material is not particularly limited, such as water-based, emulsion, and solvent-based. The curing method can also be appropriately selected from a one-component type, a two-component type, an ultraviolet curing method, and the like.

As the resin material used as the main component of the topcoat layer 7, a urethane-based resin material 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 bis (isocyanate methyl). It can be appropriately selected from curing agents such as adduct, buretto, and isocyanurate, which are derivatives such as cyclohexane (HXDI) and trimethylhexamethylene diisocyanate (TMDI), but it is linear in consideration of weather resistance. Hexamethylene diisocyanate (HMDI) or isophorone diisocyanate (IPDI) -based curing agent having the above molecular structure is suitable. In addition to this, when improving 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 a thermosetting type and a photocuring type, the surface hardness can be improved, the curing shrinkage can be suppressed, and the adhesion can be improved. Can be planned.

A gloss adjuster can be added to the top coat layer 7 for gloss adjustment. As the gloss adjusting agent, a known commercially available product may be used. As the gloss adjuster, for example, fine particles made of an inorganic material such as silica, glass, alumina, calcium carbonate, and barium sulfate may be used. Alternatively, fine particles made of an organic material such as acrylic can be used. However, when high transparency is required, it is desirable to use fine particles such as silica, glass, and acrylic having high transparency. In particular, among the fine particles such as silica and glass, a gloss adjuster having a low bulk density in which fine primary particles are secondarily aggregated instead of solid subatomic particles has a high matting effect on the amount of addition. Therefore, by using such a gloss adjusting agent, the amount of the gloss adjusting agent added can be reduced.

Further, in order to impart various functions to the top coat layer 7, functional additives such as an antibacterial agent and an antifungal agent may be added. Further, an ultraviolet absorber and a light stabilizer may be added as needed. As the ultraviolet absorber, for example, benzotriazole-based, benzoate-based, benzophenone-based, triazine-based, and cyanoacrylate-based can be used. Further, as the light stabilizer, a hindered amine system can be used.
The layer thickness of the top coat layer 7 is preferably in the range of 3 μm or more and 15 μm or less. When the layer thickness of the top coat layer 7 is less than 3 μm, the effect of improving the scratch resistance is low, and the significance of providing the top coat layer 7 is reduced. Further, when the layer thickness of the top coat layer 7 exceeds 15 μm, cracks and cracks occur during bending, which causes problems in design and deterioration of weather resistance.

<Primer layer 8>
As the material of the primer layer 8, basically the same material as that of the pattern layer 5 can be used. Considering that it is applied to the back surface of the decorative sheet 1 and wound up in a web shape, in order to avoid blocking and to improve the adhesion with the adhesive, for example, silica, alumina, magnesia, and oxidation are applied to the primer layer 8. Inorganic fillers such as titanium and barium sulfate may be added. The coating thickness of the primer layer 8 is preferably in the range of 0.1 μm or more and 3.0 μm or less because the purpose is to ensure adhesion with the base material B. The primer layer 8 is necessary when the white sheet 2 has an inert surface such as an olefin-based material, but is not particularly necessary when the surface is active.

"Production method"
An example of manufacturing the decorative sheet 1 will be described.
The polypropylene resin used for the colored layer 3 is preferably mixed with a random polypropylene resin having ethylene content or a known amorphous polypropylene resin within a predetermined range in order to facilitate dispersion of the inorganic pigment described later. As the polypropylene resin used for the skin layer 4, it is preferable to use a homopolypropylene resin having high crystallinity. The polypropylene resin may be used alone or in combination.
The resin material for the white sheet is heated and melted and molded into a sheet having a thickness of 50 μm or more and 150 μm or less by extrusion molding or the like to obtain a white sheet 2.
Further, if necessary, a pattern layer 5 is formed on the upper surface of the white sheet 2 by printing, and at least one of the transparent resin layer 6 and the top coat layer 7 is formed on the pattern layer 5.

<Action and others>
(1) In the white sheet 2 of the present embodiment, the reflectance chromaticity measured by the D65 light source is in the range of 90 or more and 100 or less for L * in the Lab color system, and a * is −1.5 or more and +1. It is in the range of .5 or less, b * is in the range of −1.5 or more and 2.0 or less, and the spectral reflectance is in the range of 500 nm or more and 650 nm or less.
With such a configuration, the white sheet 2 having excellent flexibility and excellent concealing property because it is not necessary to increase the amount of the inorganic pigment added as compared with the prior art, and the white sheet 2 thereof are provided. The decorative sheet 1 can be provided.

(2) The white sheet 2 of the present embodiment has a colored layer 3 containing an inorganic pigment and a resin, and may contain titanium oxide and at least one kind of blue pigment as the inorganic pigment.
With such a configuration, it is possible to reliably provide a white sheet 2 having excellent whiteness and a decorative sheet 1 provided with the white sheet 2.

(3) The white sheet 2 of the present embodiment may contain at least one selected from ultramarine, prussian blue, cobalt blue, cerulean blue, and Kuresu as the blue pigment. ..
With such a configuration, it is possible to reliably provide a white sheet 2 having further excellent whiteness and a decorative sheet 1 provided with the white sheet 2.

(4) The white sheet 2 of the present embodiment may have a blue pigment content in the range of 1 part by mass or more and 2 parts by mass or less when titanium oxide is 100 parts by mass.
With such a configuration, it is possible to reliably provide a white sheet 2 having further excellent whiteness and a decorative sheet 1 provided with the white sheet 2.

(5) In the white sheet 2 of the present embodiment, the resin contained in the colored layer 3 may be polypropylene.
With such a configuration, the white sheet 2 having excellent flexibility and excellent concealing property because it is not necessary to increase the amount of the inorganic pigment added as compared with the prior art, and the white sheet 2 thereof are provided. The decorative sheet 1 can be provided.

(6) The white sheet 2 of the present embodiment further has a skin layer 4 formed on at least one surface of the colored layer 3, and the skin layer 4 may contain a polypropylene resin.
With such a configuration, it is possible to reduce the bleeding of the inorganic pigment.

(7) The thickness of the white sheet 2 of the present embodiment may be in the range of 50 μm or more and 150 μm or less.
With such a configuration, it is possible to impart both non-landing property and bendability to the white sheet 2.

[Example]
A specific example of the decorative sheet 1 of the present embodiment will be described below.

(Example 1)
As a raw material for the colored layer 3, 59.6 parts by mass of a polypropylene resin was added and mixed so as to be 40 parts by mass of a titanium oxide pigment and 0.4 parts by mass of a cobalt blue pigment as an inorganic pigment. As a raw material for the skin layer 4, 0.5 parts by mass of a hindered amine-based light stabilizer (BASF's "Kimasorb 944") and a benzotriazole-based ultraviolet absorber (BASF's "Chinubin 328") are used as raw materials for the polypropylene resin. ) And mixed so as to be 0.5 parts by mass. The mixture of the colored layer 3 and the mixture of the skin layer 4 are co-extruded in the order of the skin layer 4, the colored layer 3, and the skin layer 4 using a melt extruder so as to have a thickness of 10 μm: 120 μm: 10 μm. The white sheet 2 was formed into a film.

(Example 2)
The white sheet 2 was formed by co-extruding using a melt extruder in the same manner as in Example 1 except that the cobalt blue pigment added to the colored layer 3 was added so as to be 0.8 parts by mass. ..
(Example 3)
Regarding the blue pigment added to the coloring layer 3 described above, a white sheet was co-extruded using a melt extruder in the same manner as in Example 1 except that the ultramarine blue pigment was added so as to be 0.4 parts by mass. 2 was formed.

(Example 4)
The white sheet 2 was formed by co-extruding using a melt extruder in the same manner as in Example 1 except that the cobalt blue pigment added to the colored layer 3 was added so as to be 0.2 parts by mass. ..
(Example 5)
Using the same mixture of the colored layer 3 and the mixture of the skin layer 4 as in Example 1, a melt extruder so as to have a thickness of 3 μm: 44 μm: 3 μm in the order of the skin layer 4, the colored layer 3, and the skin layer 4. The white sheet 2 was formed into a film by coextrusion using the above.

(Example 6)
Using the same mixture of the colored layer 3 and the mixture of the skin layer 4 as in Example 1, a melt extruder so as to have a thickness of 3 μm: 94 μm: 3 μm in the order of the skin layer 4, the colored layer 3, and the skin layer 4. The white sheet 2 was formed into a film by coextrusion using the above.
(Example 7)
Using the same mixture of the colored layer 3 and the mixture of the skin layer 4 as in Example 1, a melt extruder so as to have a thickness of 3 μm: 34 μm: 3 μm in the order of the skin layer 4, the colored layer 3, and the skin layer 4. The white sheet 2 was formed into a film by coextrusion using the above.

(Example 8)
Using the same mixture of the colored layer 3 and the mixture of the skin layer 4 as in Example 1, a melt extruder so as to have a thickness of 10 μm: 160 μm: 10 μm in the order of the skin layer 4, the colored layer 3, and the skin layer 4. The white sheet 2 was formed into a film by coextrusion using the above.
(Example 9)
A pattern layer 5 was formed by printing a pattern on the surface of a white sheet 2 having a thickness of 140 μm, which was produced in the same manner as in Example 1. In the pattern layer 5, 0.5 parts by mass of a hindered amine-based light stabilizer (Kimasorb 944; manufactured by BASF) is added to a two-component urethane ink (V180; manufactured by Toyo Ink Co., Ltd.) with respect to the binder resin content of the ink. It was formed using the added ink. In addition, a primer layer 8 was formed on the back surface of the white sheet 2. The primer layer 8 was formed by printing the same two-component urethane ink as the pattern layer 5. Further, a two-component curable urethane top coat (“W184” manufactured by DIC Graphics Corporation) was applied at a coating amount of 3 g / m ² to form a top coat layer 7. In this way, the decorative sheet 1 having a thickness of 145 μm shown in FIG. 3 was obtained.

(Example 10)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 140 μm prepared in the same manner as in Example 2 in the same manner as in Example 9 to obtain a decorative sheet 1 having a thickness of 145 μm.
(Example 11)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 140 μm prepared in the same manner as in Example 3 in the same manner as in Example 9 to obtain a decorative sheet 1 having a thickness of 145 μm.

(Example 12)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 140 μm prepared in the same manner as in Example 4 in the same manner as in Example 9, and a decorative sheet 1 having a thickness of 145 μm was obtained.
(Example 13)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 50 μm prepared in the same manner as in Example 5 in the same manner as in Example 9 to obtain a decorative sheet 1 having a thickness of 55 μm.

(Example 14)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 100 μm prepared in the same manner as in Example 6 in the same manner as in Example 9 to obtain a decorative sheet 1 having a thickness of 105 μm.
(Example 15)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 40 μm prepared in the same manner as in Example 7 in the same manner as in Example 9 to obtain a decorative sheet 1 having a thickness of 45 μm.

(Example 16)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 180 μm prepared in the same manner as in Example 8 in the same manner as in Example 9, and a decorative sheet 1 having a thickness of 185 μm was obtained.
(Example 17)
The white sheet 2 was formed by co-extruding using a melt extruder in the same manner as in Example 1 except that the cobalt blue pigment added to the colored layer 3 was added so as to be 1.0 part by mass. ..

(Example 18)
A top coat layer 7 was formed on the white sheet 2 having a thickness of 140 μm prepared in the same manner as in Example 17 in the same manner as in Example 9 to obtain a decorative sheet 1.
(Example 19)
The white sheet 2 was formed by co-extruding using a melt extruder in the same manner as in Example 1 except that the polypropylene resin was used as the polyethylene resin as the raw material of the colored layer 3 described above.

(Example 20)
Melt extrusion is the same as in Example 1 except that the polypropylene resin 69.7 parts by mass, the titanium oxide pigment is 30 parts by mass, and the cobalt blue pigment is 0.3 parts by mass as the raw materials of the colored layer 3 described above. The white sheet 2 was formed by co-extrusion using a machine.
(Example 21)
The white sheet 2 was formed by co-extruding using a melt extruder in the same manner as in Example 1 except that the skin layer 4 was not formed.
(Example 22)
Melt extrusion is the same as in Example 1 except that the raw material of the colored layer 3 is 79.8 parts by mass of polypropylene resin, 20 parts by mass of titanium oxide pigment, and 0.2 parts by mass of cobalt blue pigment. The white sheet 2 was formed by co-extrusion using a machine.

(Comparative Example 1)
The white sheet 2 was formed into a film by co-extrusion using a melt extruder in the same manner as in Example 5 except that the above-mentioned blue pigment was not added.
(Comparative Example 2)
A pattern layer 5 was formed by printing a pattern on the surface of a white sheet 2 having a thickness of 50 μm, which was produced in the same manner as in Comparative Example 1. In the pattern layer 5, 0.5 parts by mass of a hindered amine-based light stabilizer (Kimasorb 944; manufactured by BASF) is added to a two-component urethane ink (V180; manufactured by Toyo Ink Co., Ltd.) with respect to the binder resin content of the ink. It was formed using the added ink. In addition, a primer layer 8 was formed on the back surface of the white sheet 2. The primer layer 8 was formed by printing the same two-component urethane ink as the pattern layer 5. Further, a two-component curable urethane top coat (“W184” manufactured by DIC Graphics Corporation) was applied at a coating amount of 3 g / m ² to form a top coat layer 7. In this way, the decorative sheet 1 having a thickness of 55 μm shown in FIG. 3 was obtained.
(Comparative Example 3)
The white sheet 2 was formed by co-extruding using a melt extruder in the same manner as in Example 1 except that the cobalt blue pigment added to the colored layer 3 was added so as to be 1.2 parts by mass. ..

[Evaluation]
The spectral reflectance, hue, concealing property, and bending suitability of Examples 1 to 22 and Comparative Examples 1 to 3 were evaluated.

<Spectroreflectance>
For the spectral reflectance measurement, a fluorescence spectrophotometer (FD-7) manufactured by Konica Minolta Co., Ltd. was used to obtain a spectral reflectance of 400 to 700 nm. Since a white sheet having low hiding power is affected by the color of the base, all the sheets were measured on a white base of a concealment test paper (byko-chart high brightness 2A) manufactured by BYK-GARDNER.
The spectral reflectances of Examples 1 to 4 and Comparative Example 1 are shown in FIG. Since Examples 1 to 4 have a blue pigment added, they have a minimum value at 500 nm to 650 nm, but Comparative Example 1 shows a monotonically decreasing spectral reflectance because no blue pigment is added.

<Hue>
The hue was evaluated using a spectrophotometer (530JP / LP) manufactured by X-rite, using a D65 light source, and measured on a white background of a concealment test paper (byko-chart high brightness 2A) manufactured by BYK-GARDNER. It was evaluated by chromaticity.

<Concealment>
The concealing property was evaluated by using a spectrophotometer (530JP / LP) manufactured by X-rite and measuring the color difference between the white background and the black background of the concealment test paper (byko-chart high brightness 2A) manufactured by BYK-GARDNER. Judged by. The smaller the color difference, the better the hiding property. When it is 0.5 or less, it is "◎", when it is more than 0.5 and 0.7 or less, it is "○", and when it is more than 0.7 and 1.0 or less, it is "△". , And the case of more than 1.0 was defined as "x". If the evaluation is "Δ" or higher, there is no problem in practical use.

<Bending process suitability>
In the bending suitability test, first, urethane sheets of Examples 1 to 22 and Comparative Examples 1 to 3 obtained by the above method were applied to one surface of the medium density fiberboard (MDF) as the substrate B. It was attached using a system adhesive. With respect to the other surface of the substrate B, a V-shaped groove is inserted up to the boundary where the substrate B and the decorative sheet 1 are bonded so that the decorative sheet 1 on the opposite side is not scratched. Next, the substrate B is bent up to 90 degrees along the V-shaped groove so that the surface of the decorative sheet 1 is mountain-folded, and whether the bent portion of the surface of the decorative sheet 1 is whitened or cracked. Was observed using an optical microscope, and the state of bending workability was evaluated.
"◎" if no whitening or cracks are seen, "○" if some whitening is visible, "△" if some whitening is visible, or if whitening is visible on the entire surface or partly The case where a crack is visible is marked with "x". If the evaluation is "Δ" or higher, there is no problem in practical use.

The results of these evaluations are shown in Table 1.

As can be seen from Table 1, the decorative sheets of Examples 1 to 3 and 9 to 11 had very good concealing properties and had no problem in bending. Further, in each of the decorative sheets of Examples 9 to 11, the pattern layer 5 and the top coat layer 7 are laminated on the decorative sheets of Examples 1 to 3, and while giving a high design, both hiding property and bending process are compatible. You can see that it is made.
Since each of the decorative sheets of Examples 4 and 12 was produced with a composition in which the amount of the blue pigment added was as small as 0.2, the hiding property was slightly poor, but it was at a level where there was no problem in practical use.
Since each of the decorative sheets of Examples 5 and 13 was prepared so that the thickness of the colored layer was as thin as 44 μm, the hiding property was slightly poor, but it was at a level where there was no problem in practical use.

Since each of the decorative sheets of Examples 6 and 14 was prepared so that the thickness of the colored layer was as thin as 94 μm, the hiding property was slightly poor, but it was at a level where there was no problem in practical use.
Each of the decorative sheets of Examples 7 and 15 was prepared so that the thickness of the colored layer was as thin as 34 μm, so that the hiding property was very poor, but there was no problem in practical use.
Since each of the decorative sheets of Examples 8 and 16 was prepared so that the thickness of the colored layer was as thick as 160 μm, the hiding property was very good, but the bending workability was deteriorated. However, there was no problem in practical use.

Since each of the decorative sheets of Examples 17 and 18 was prepared with a large amount of blue pigment added as 1.0, the hue was closer to bluish (b * is on the minus side), but at a level where there is no practical problem. there were.
The decorative sheet of Example 19 used polyethylene resin instead of polypropylene resin, but the finish was not a problem.
The decorative sheet of Example 20 had a titanium oxide concentration of 30 parts by mass, which was lower than that of Example 1, and thus the concealing property was slightly deteriorated, but it was at a level where there was no problem in practical use.
Since the decorative sheet of Example 21 does not have a skin layer, the hiding property is slightly deteriorated, but the level is not a problem in practical use.
The decorative sheet of Example 22 had a titanium oxide concentration of 20 parts by mass, which was considerably lower than that of Example 1, and thus the concealing property was slightly deteriorated, but it was at a level where there was no problem in practical use.

Since the decorative sheets of Comparative Examples 1 and 2 did not contain a blue pigment, they did not have a minimum value in the spectral reflectance of 500 nm to 650 nm, and as a result, the decorative sheets were inferior in hiding power.
The decorative sheet of Comparative Example 3 was produced with a very large amount of blue pigment added of 1.2, so that the hue was blue (b * value was -1.75), which was a level that could not be called a white sheet. It was.

As described above, the present invention is particularly suitable for decorative sheets used as building materials for exteriors and interiors of buildings, surfaces of fittings, surface materials of home appliances, and the like.

1 ... decorative sheet, 2 ... white sheet, 3 ... colored layer, 4 ... skin layer, 5 ... pattern layer, 6 ... transparent resin layer, 6a ... embossed pattern, 6b ... adhesive resin layer, 7 ... top coat layer, 8 ... Primer layer, B ... Base material

Claims (9)

The reflected chromaticity measured by the D65 light source is in the range of 90 or more and 100 or less for L * in the Lab color system, a * is in the range of -1.5 or more +1.5 or less, and b * is. Within the range of -1.5 or more and 2.0 or less,
A white sheet having a spectral reflectance in the range of 500 nm or more and 650 nm or less. The white sheet according to claim 1, wherein the white sheet has a colored layer containing an inorganic pigment and a resin, and contains titanium oxide and at least one kind of blue pigment as the inorganic pigment. The white sheet according to claim 2, wherein the blue pigment contains at least one selected from ultramarine, prussian blue, cobalt blue, cerulean blue, and Kuresu. The white sheet according to claim 2 or 3, wherein the content of the blue pigment is in the range of 1 part by mass or more and 2 parts by mass or less when titanium oxide is 100 parts by mass. The white sheet according to any one of claims 2 to 4, wherein the resin contained in the colored layer is polypropylene. The white sheet further has a skin layer formed on at least one surface of the colored layer.
The white sheet according to any one of claims 2 to 5, wherein the skin layer contains a polypropylene resin. The white sheet according to any one of claims 1 to 6, wherein the thickness of the white sheet is within the range of 50 μm or more and 150 μm or less. A decorative sheet comprising at least the white sheet according to any one of claims 1 to 7, and a top coat layer. The method for manufacturing a decorative sheet according to claim 8.
A method for producing a decorative sheet, which comprises mixing an inorganic pigment with a resin to prepare a white sheet so that the spectral reflectance has a minimum value within the range of 500 nm or more and 650 nm or less.

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