JP7743706B2 - Recoatable decorative sheet and coloring method for decorative sheet using the same - Google Patents

Description

The present invention relates to a decorative sheet for recoating and a method for coloring a decorative sheet using the same.

It is common practice, primarily in Europe and the United States, for ordinary consumers to paint the surfaces of wooden building interior materials, furniture surfaces, etc., using colored paints such as water-based or oil-based stains, or to paint the surfaces of wooden furniture (DIY: Do It Yourself). Such stains penetrate the wood to color it, and because they do not conceal the wood grain or form a film on the surface, they have the advantage of making the most of the wood's unique design and appearance, such as the grain and luster (pearl-like luster).

In recent years, decorative sheets made by printing wood grain patterns on the surface of a sheet-like substrate, rather than natural wood, have begun to be used as interior building materials and surface materials for furniture, etc., and decorative sheets that can be stained using the above-mentioned stain paints are now being manufactured. Specifically, these recoatable decorative sheets are surface-treated to ensure the adhesion of stain paint, with the expectation that purchasers will apply the stain paint themselves to achieve the desired texture.

Such decorative sheets have been proposed as recoatable decorative sheets, in which a design layer is printed on a polyvinyl chloride (PVC) resin substrate and then heat-fused to a nonwoven fabric (see, for example, Patent Document 1), and stainable decorative sheets, in which a paper substrate and nonwoven fabric are used (see, for example, Patent Document 2). These recoatable and stainable decorative sheets are popular with consumers because they can be recoated, and the nonwoven fabric imparts a fine irregularity to the surface, giving them a texture very similar to that of wood.

Japanese Patent Application Publication No. 9-262934 Japanese Patent Application Laid-Open No. 2019-64131

However, using a PVC substrate as the base material raises the problem of the high cost of the decorative sheet. Furthermore, when a PVC substrate is used as the base material, incineration can pose an environmental problem, as it generates gases containing chlorine atoms, such as hydrogen chloride (HCl), when disposed of.

To address the above-mentioned problems, it has been considered to change the substrate to a paper substrate, but such a change is expected to cause various problems.
For example, when laminating a nonwoven fabric on a paper substrate, the paper substrate and the nonwoven fabric do not adhere to each other, so the method of adhering the paper substrate and the nonwoven fabric becomes an issue. If an adhesive layer is provided between the paper substrate and the nonwoven fabric to adhere them, the unevenness of the nonwoven fabric may be lost, which may cause a problem of losing the tactile feel that closely resembles wood. On the other hand, if the unevenness of the nonwoven fabric is taken advantage of too much, the tactile feel may be lost due to fluffing of the nonwoven fabric, and the fluffing (surface unevenness) and even the difference in refractive index due to the voids in the fibers that make up the nonwoven fabric may cause a problem of reduced transparency of the decorative sheet and a decrease in designability.

To prevent a decrease in transparency due to changes in refractive index and a decrease in tactile feel due to fuzzing, one option is to provide a surface layer. However, providing a surface layer can reduce the penetration and adhesion of stains and other colored paints. On the other hand, using a material with high affinity for stains and other colored paints to improve penetration and adhesion can cause appearance problems, such as the surface layer deteriorating and whitening due to the solvents (water, solvents, alcohol, etc.) contained in stains and other colored paints. This problem is not limited to stains and other colored paints, and can also occur outdoors when exposed to wind and rain.

For this reason, it is difficult to achieve both the application suitability (called "stainability" in English, but the term "stainable" is used even when used as a noun in this specification) that ensures the penetration and adhesion of stain paint and other colored paints, while also achieving surface properties (such as water resistance) that prevent deterioration (such as whitening) caused by stain paint and other colored paints.

In view of the above problems, the present invention aims to provide a recoatable decorative sheet that has excellent stainability and excellent surface properties such as water resistance, as well as a method for coloring decorative sheets using the same.

As a result of extensive research conducted by the inventors to solve the above problems, they discovered that the above problems can be solved by a decorative recoat sheet having the following configuration.

1. A recoat decorative sheet comprising, in order, a paper base material, an adhesive layer, a nonwoven fabric layer, and a surface layer composed of a cured product of a composition containing a polyol compound having hydroxyl groups in its molecule and an isocyanate curing agent, wherein the nonwoven fabric layer partially has, on the side of the layer thickness where the adhesive layer is provided, a filled section A in which the resin forming the adhesive layer fills some of the voids in the fibers constituting the nonwoven fabric layer, and on the side of the layer thickness where the surface layer is provided, a filled section B in which the cured product fills some of the voids in the fibers constituting the nonwoven fabric layer, wherein the content of residual hydroxyl groups in the surface layer is 0.25% by mass or more and 1.10% by mass or less, and the ratio ( _CNCO / _COH ) of the amount of isocyanate groups C _NCO (mmol) in the isocyanate curing agent to the amount of hydroxyl groups C _OH (mmol) in the polyol compound is 0.20 or more.
2. The decorative sheet for recoat according to the above item 1, wherein the fibers are at least one type of fibers selected from thermoplastic resin fibers and recycled fibers.
3. The decorative sheet for recoat according to the above 1 or 2, wherein the fibers are cellulose resin fibers.
4. The decorative sheet for recoat according to any one of the above items 1 to 3, wherein the resin forming the adhesive layer is at least one resin selected from the group consisting of urethane resins and polyolefin resins.
5. A decorative recoat sheet according to any one of 1 to 4 above, wherein the polyol compound is at least one selected from acrylic polyol, polyester polyol, polyether polyol, and polycarbonate polyol. 6. A decorative recoat sheet according to any one of 1 to 5 above, wherein the isocyanate curing agent is a polyvalent isocyanate compound.
7. The decorative sheet for recoat according to any one of the above items 1 to 6, further comprising a decorative layer between the paper substrate and the adhesive layer.
8. The decorative sheet for recoat according to the above item 7, wherein the decorative layer has a wood grain pattern.
9. A method for coloring a decorative sheet, comprising applying a colored coating to the surface of the surface layer side of the decorative sheet for recoat described in any one of 1 to 8 above, thereby coloring the nonwoven fabric layer.

The present invention provides a recoatable decorative sheet that has excellent stainability and excellent surface properties such as water resistance, as well as a method for coloring decorative sheets using the same.

1 is a schematic cross-sectional view showing one embodiment of a decorative sheet for recoating according to the present embodiment. 1 is a schematic cross-sectional view showing one embodiment of a decorative sheet for recoating according to the present embodiment.

An embodiment of the present invention (hereinafter sometimes referred to as "this embodiment") will be described below. Note that in this specification, the numerical values associated with "greater than or equal to," "less than or equal to," and "to" when describing a numerical range can be arbitrarily combined, and the numerical values in the examples are numerical values that can be used as the upper and lower limits of the numerical range.

[Decorative sheet for recoating]
The decorative sheet for recoat of this embodiment comprises, in order, a paper base material, an adhesive layer, a nonwoven fabric layer, and a surface layer constituted by a cured product of a composition containing a polyol compound having hydroxyl groups in its molecule and an isocyanate curing agent; the nonwoven fabric layer partially has, on the side of the layer thickness where the adhesive layer is provided, a filled portion A in which the resin forming the adhesive layer fills some of the voids in the fibers constituting the nonwoven fabric layer, and on the side of the layer thickness where the surface layer is provided, a filled portion B in which the cured product fills some of the voids in the fibers constituting the nonwoven fabric layer; the content of residual hydroxyl groups in the surface layer is 0.25% by mass or more and 1.10% by mass or less; and the ratio ( _CNCO / _COH ) of the amount of isocyanate groups C _NCO (mmol) in the isocyanate curing agent to the amount of hydroxyl groups C _OH (mmol) in the polyol compound is 0.20 or more.

The decorative recoat sheet of this embodiment has the above-described configuration, and thus has excellent stainability and excellent surface properties such as water resistance.
Generally, when a surface layer is provided to improve surface properties such as water resistance or scratch resistance, stainability tends to decrease. To improve surface properties, the affinity with colored paints such as stain paints is reduced, that is, a material with low affinity is used, which makes it easier to suppress deterioration of the material caused by the colored paint, mainly the solvents (water, solvent, alcohol, etc.) contained in the colored paint, and to prevent whitening. However, with a material with low affinity with the colored paint, it becomes difficult to obtain the application suitability that ensures the penetration and ink-receiving ability of the colored paint, that is, stainability.

The polyol compound having a hydroxyl group in its molecule (hereinafter sometimes simply referred to as "polyol compound") used in this embodiment is a material that inherently has a high affinity with colored paints such as stain paints, i.e., has a high affinity with the solvents (water, solvent, alcohol, etc.) contained in the colored paints, making it easy to achieve excellent stainability. However, this high affinity with colored paints can conversely accelerate the degradation of the polyol compound, causing whitening and other deterioration in surface properties such as water resistance.

In the recoat decorative sheet of this embodiment, excellent stainability is obtained by using a polyol compound having such properties, and the surface layer is composed of a cured product of a composition containing a polyol compound and an isocyanate curing agent, and the content of residual hydroxyl groups in the surface layer is set to a range of 0.25% by mass or more and 1.10% by mass or less, and the ratio ( _CNCO / _COH ) of the amount of isocyanate groups C _NCO (mmol) in the isocyanate curing agent to the amount of hydroxyl groups C _OH (mmol) in the polyol compound is set to 0.20 or more. In other words, by using a certain amount or more of isocyanate curing agent to obtain a good cured state of the cured product, while leaving some of the hydroxyl groups in the polyol compound remaining, it is possible to achieve a high level of compatibility between stainability and surface properties such as water resistance, which are contradictory properties.

It can be said to be a surprising effect that the conflicting properties of stainability and surface properties such as water resistance can be achieved at a high level by the relatively easy method of adjusting the content and ratio (C _NCO /C _OH ) of the residual hydroxyl groups by the types of polyol compound and isocyanate curing agent used as the base agents and the amounts used depending on the types. And this effect is possible only because a polyol compound is selected as the base agent and a urethane resin (cured product) using an isocyanate curing agent is used as the material for forming the surface layer.
Furthermore, when a resin composition using a PVC-based resin is used to form a layer, as with the substrate, incineration for disposal may generate gases containing chlorine atoms, such as hydrogen chloride (HCl), which may cause environmental problems. Therefore, one of the benefits of using a urethane resin (cured product) to form the surface layer is the reduction of the burden on the environment. Furthermore, it is preferable not to use PVC resin not only for the substrate and surface layer, but also for forming other layers.

The recoatable decorative sheet of this embodiment will be described below with reference to the drawings. In the following description of the drawings, identical or similar parts are represented by identical or similar symbols. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc., differ from reality. Therefore, specific thicknesses and dimensions should be determined in reference to the following description. Furthermore, it goes without saying that the drawings also include parts with different dimensional relationships and ratios.

The recoatable decorative sheet 1 shown in Figure 1 comprises, in that order, a paper substrate 10, an adhesive layer 20, a nonwoven fabric layer 30, and a surface layer 40, with the adhesive layer 20 provided on at least one surface 11 of the paper substrate 10. The nonwoven fabric layer 30 is shown to have a filled portion A31 on the surface 30a where the adhesive layer 20 is provided in the thickness direction of the layer (hereinafter also referred to as the "surface where the adhesive layer of the nonwoven fabric layer is provided"), where the resin that forms the adhesive layer 20 fills some of the voids in the fibers that make up the nonwoven fabric layer 30, and a filled portion B33 on the surface 30b where the surface layer 40 is provided in the thickness direction of the layer (hereinafter also referred to as the "surface where the surface layer of the nonwoven fabric layer is provided") where the composition that forms the surface layer 40 fills some of the voids in the fibers that make up the nonwoven fabric layer 30. The nonwoven fabric layer 30 is also shown to have a fiber portion 32 between filling portion A31 and filling portion B33, as a portion other than filling portion A31 and filling portion B32.

In addition, the recoating sheet 1 shown in Figure 2 is the recoating sheet 1 shown in Figure 1, and has a decorative layer 50 consisting of a full-colored layer 51 and a picture layer 52 between the paper base material 10 and the adhesive layer 20.
Hereinafter, each layer constituting the decorative sheet for recoat of this embodiment will be described with reference to FIGS.

[Surface layer 40]
The surface layer 40 in the recoat decorative sheet of this embodiment is composed of a cured product of a composition containing a polyol compound having hydroxyl groups in its molecule and an isocyanate curing agent, and the content of residual hydroxyl groups contained in the surface layer is 0.25% by mass or more and 1.10% by mass or less. By having the surface layer 40, it is possible to achieve a high level of both surface properties such as water resistance and stainability, as described above.

(Residual Hydroxyl Group Content)
The surface layer 40 is composed of a cured product of a composition containing a polyol compound and an isocyanate curing agent (hereinafter sometimes simply referred to as the "curing agent"), and contains 0.25% to 1.10% by mass of residual hydroxyl groups. If the content of residual hydroxyl groups is less than 0.25% by mass, the surface layer 40 will not have affinity with colored paints such as stain paints, and therefore will not be stainable. On the other hand, if the content of residual hydroxyl groups is more than 1.10% by mass, the surface layer 40 will have too high an affinity with solvents (water, solvents, alcohol, etc.), especially water, which will accelerate deterioration of the surface layer and make it more susceptible to whitening, and therefore will not have surface properties such as water resistance and scratch resistance.

From the perspective of improving surface properties as well as stainability, the content of residual hydroxyl groups in the surface layer 40 is preferably 0.30% by mass or more, more preferably 0.35% by mass or more, even more preferably 0.40% by mass or more, and even more preferably 0.45% by mass or more, with the upper limit being preferably 1.05% by mass or less, more preferably 1.00% by mass or less, even more preferably 0.95% by mass or less, and even more preferably 0.90% by mass or less. Note that, because the surface layer 40 is composed of a cured product, the content of residual hydroxyl groups in the surface layer 40 is substantially the same as the content of residual hydroxyl groups in the cured product.

In this specification, the content of residual hydroxyl groups in the surface layer 40 refers to the content (mass %) of hydroxyl groups in the polyol compound contained in the resin composition that remain without forming a urethane bond by reacting with an isocyanate group (—NCO) in the curing agent relative to the cured product constituting the surface layer 40, more specifically, the total amount of the polyol compound and the curing agent. Specifically, this content can be calculated by the following method.
The hydroxyl value X _OH (mg KOH/g) of a polyol compound having hydroxyl groups in the molecule is determined based on JIS K1557-1:2007 (Plastics - Test methods for polyurethane raw polyols - Part 1: Determination of hydroxyl value). Using the determined hydroxyl value X _OH and the following amounts, the content of residual hydroxyl groups is calculated according to the following mathematical formula (1):

Residual hydroxyl group content (mass%) = (amount of residual hydroxyl groups) / (amount of polyol compound used + amount of curing agent used) × 100 (1)
Amount of remaining hydroxyl groups = Amount of hydroxyl groups in polyol compound - Amount of isocyanate groups in curing agent Amount of hydroxyl groups in polyol compound (g) = X _OH / 56.1 × _{A P} × 17.0
Amount of isocyanate groups in curing agent (g) = X _NCO × A _C × 42.0
A _P (g): Amount of polyol compound used A _C (g): Amount of curing agent used X _NCO (mmol/g): Content of isocyanate groups in the curing agent

(Ratio of isocyanate group amount to hydroxyl group amount)
In the surface layer 40, the ratio ( _CNCO / _COH ) of the amount of isocyanate groups C _NCO (mmol) in the isocyanate curing agent to the amount of hydroxyl groups C _OH (mmol) in the polyol compound must be 0.20 or more. If this ratio is less than 0.20, the proportion of crosslinking caused by the isocyanate groups will be low, making it impossible to obtain excellent surface properties.

The ratio ( _CNCO / _COH ) of the amount of isocyanate groups C _NCO (mmol) in the curing agent to the amount of hydroxyl groups C _OH (mmol) in the polyol compound is preferably 0.25 or more, more preferably 0.30 or more, from the viewpoint of improving stainability and surface properties. There is no particular upper limit, but in order to improve stainability, it is preferably 0.90 or less, more preferably 0.80 or less, even more preferably 0.60 or less, and still more preferably 0.45 or less.

Here, the amount of isocyanate groups C _NCO (mmol) in the curing agent and the amount of hydroxyl groups C _OH (mmol) in the polyol compound are values calculated by the following formulas (2) and (3).
Amount of isocyanate group in curing agent C _NCO (mmol) = X _NCO × A _C (2)
Amount of hydroxyl groups in the polyol compound C _OH (mmol) = X _OH /56.1 × _{A P} (3)

(Polyol Compound)
The surface layer 40 is made of a cured product of a composition containing a polyol compound having a hydroxyl group in the molecule and an isocyanate curing agent.
Preferred examples of the polyol compound include acrylic polyol, polyester polyol, polyether polyol, and polycarbonate polyol, which can be used alone or in combination. From the viewpoint of improving the surface properties as well as the stainability, acrylic polyol is particularly preferred.

Specific examples of acrylic polyols include those in which a plurality of hydroxyl groups have been introduced by copolymerizing an alkyl (meth)acrylate ester such as ethyl (meth)acrylate with a hydroxyacrylate such as 2-hydroxyethyl acrylate or 2-hydroxy-3-phenoxypropyl acrylate.
Specific examples of polyester polyols include poly(ethylene adipate), poly(butylene adipate), poly(neopentyl adipate), poly(hexamethylene adipate), poly(butylene azelaate), poly(butylene sebacate), and polycaprolactone.

Specific examples of polyether polyols include those having alkyleneoxy groups as repeating units, such as polyoxyethylene monomethyl ether, polyethylene glycol, polyoxyethylene glycerol ether, polyoxyethylene trimethylolpropane ether, polyoxyethylene neopentylglycerol ether, polyoxyethylene pentaerythritol ether, polypropylene glycol, and polytetramethylene glycol.

Specific examples of polycarbonate polyols include polycarbonate diols produced by condensing one or more alkylene diols having an alkylene group containing 4 to 12 carbon atoms with a low-molecular-weight carbonate compound (e.g., dialkyl carbonates having an alkyl group containing 1 to 6 carbon atoms, alkylene carbonates having an alkylene group containing 2 to 6 carbon atoms, and diaryl carbonates having an aryl group containing 6 to 9 carbon atoms) while causing a dealcoholization reaction. More specific examples include polybutylene carbonate polyol, polyhexamethylene carbonate polyol, and polycyclohexanedimethylene carbonate polyol.

The polyol compound preferably has a hydroxyl value (mgKOH/g) of 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, even more preferably 15 mgKOH/g or more, and even more preferably 20 mgKOH/g or more, with the upper limit being preferably 60 mgKOH/g or less, more preferably 55 mgKOH/g or less, even more preferably 50 mgKOH/g or less, and even more preferably 45 mgKOH/g or less. When the hydroxyl value of the polyol compound is within the above range, it is easy to adjust the residual hydroxyl group content to between 0.25% and 1.10% by mass, which improves stainability and surface properties.

(Isocyanate curing agent)
The isocyanate curing agent is preferably a polyvalent isocyanate compound, and examples thereof include aliphatic diisocyanates, aromatic diisocyanates, and prepolymer, isocyanurate, urea, and carbodiimide modified products of these diisocyanates.
Examples of the aliphatic diisocyanate include alicyclic diisocyanates such as isophorone diisocyanate (hereinafter also referred to as "IPDI"), 4,4'-dicyclohexylmethane diisocyanate (hereinafter also referred to as "DCI"), 4-methyl-1,3-cyclohexylene diisocyanate, and 1,2-bis(isocyanatomethyl)cyclohexane; and linear or branched chain aliphatic diisocyanates such as hexamethylene diisocyanate (hereinafter also referred to as "HMDI") and trimethylhexamethylene diisocyanate.
Examples of aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, and 3,3'-dimethyl-4,4'-biphenylene diisocyanate.

The content of isocyanate groups (-NCO) contained in the isocyanate curing agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, with the upper limit being preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. When the content of isocyanate groups contained in the isocyanate curing agent is within the above range, it is easy to adjust the content of residual hydroxyl groups to between 0.25% by mass and 1.10% by mass or less, which improves stainability and surface properties.

Among the above isocyanate curing agents, aliphatic chain diisocyanates are preferred, with hexamethylene diisocyanate being particularly preferred, from the viewpoint of improving surface properties as well as stainability.

The content of residual hydroxyl groups contained in the surface layer 40 can be adjusted by the type and content of the polyol compound and isocyanate curing agent contained in the composition used to form the surface layer.
The contents of the polyol compound and the isocyanate curing agent in the composition are not particularly limited as long as the content of residual hydroxyl groups is 0.25% by mass or more and 1.10% by mass or less. For example, it is preferable that the contents are set so that the ratio (CNCO/COH) of the amount of isocyanate groups C _NCO (mmol) in the curing agent to the amount of hydroxyl _groups C _OH ( _mmol ) in the polyol compound falls within the above-mentioned preferred range.

For example, the amount of isocyanate curing agent used per 100 parts by mass of polyol compound in the composition is preferably 0.3 parts by mass or more, more preferably 1.0 parts by mass or more, even more preferably 1.5 parts by mass or more, even more preferably 2.0 parts by mass or more, and particularly preferably 2.5 parts by mass or more, with the upper limit being preferably 20.0 parts by mass or less, more preferably 12.5 parts by mass or less, even more preferably 10.0 parts by mass or less, even more preferably 7.0 parts by mass or less, and particularly preferably 5.5 parts by mass or less. Keeping the amount of isocyanate curing agent used within the above range makes it easier to adjust the residual hydroxyl group content to between 0.25% and 1.10% by mass, thereby improving both stainability and surface properties. Furthermore, the isocyanate curing agent used in forming the surface layer can also contribute to improving the adhesion between the paper substrate and nonwoven fabric layer, as described below, allowing the adhesive layer to be made relatively thin.

(Aspects of Surface Layer 40)
The form of the surface layer 40 is not particularly limited as long as it is present so as to have a filled portion B in which the cured product fills some of the voids in the fibers that make up the nonwoven fabric layer. For example, as shown in Figures 1 and 2, the surface layer 40 may be present in the form of a layer with a certain thickness on the surface 30b of the nonwoven fabric layer 30, or it may be present so as to cover the outermost fibers along the surface 30b of the nonwoven fabric layer 30, i.e., so that the voids in the fibers that make up the nonwoven fabric layer 30 are present on the outermost surface.

When the surface layer 40 exists in a layer of a certain thickness, it will be present on a portion of the surface of the recoat decorative sheet of this embodiment in order to ensure the adhesion of colored paints such as water-based stain paints and oil-based stain paints and to obtain excellent stainability.
When the surface layer is present so as to cover the outermost surface fibers, from the viewpoint of ensuring ink receptivity and obtaining excellent stainability, it is preferable that voids formed by the fibers at the outermost surface and its vicinity (the vicinity in the thickness direction within the layer of nonwoven fabric layer 30) are at least partially present. From the viewpoint of improving surface properties as well as stainability, and further improving transparency, touch, etc., the surface layer is preferably present so as to cover the outermost surface fibers, and more preferably present so as to cover the entire surface.

As such, regardless of the form of the surface layer 40, in order to ensure the penetration of colored paints such as water-based stain paints and oil-based stain paints and to obtain excellent stainability, it is preferable that there be voids formed between fibers, at least some of whose surfaces may be coated with resin, at the outermost surface and its vicinity (nearby in the thickness direction within the nonwoven fabric layer 30).

Depending on the desired performance, the surface layer 40 may contain additives such as colorants such as pigments and dyes, ultraviolet absorbers, weather resistance agents such as light stabilizers, extender pigments, solvents, stabilizers, plasticizers, catalysts, etc. That is, the composition containing the polyol compound and the isocyanate curing agent used to form the surface layer 40 may contain these additives.
In this case, the content of the additives is not particularly limited as long as it is within a range that depends on the desired performance and does not inhibit the curing of the polyol compound and the isocyanate curing agent. For example, the total amount of additives used may be approximately 1 to 20 parts by mass per 100 parts by mass of the resin content of the surface layer 40 (i.e., the total amount of the polyol compound and the isocyanate curing agent), and is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, with the upper limit being preferably 15 parts by mass or less, more preferably 10 parts by mass or less.

The thickness of the surface layer 40 can be determined primarily by considering the balance between the filling section B33, the fiber section 32, and the filling section A31 in the nonwoven fabric layer 30, as well as the thickness of the surface layer 40. From the perspective of forming a balanced structure of the filling sections A31, B33, and fiber section 32, improving stainability and surface characteristics, as well as transparency and tactile feel, the total thickness of the surface layer 40 and the filling section B33 is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more, with an upper limit of preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less. The total thickness of the surface layer 40 and the filling section B33 is determined by measuring the thickness at any 30 points on a cross-sectional image taken using an electron microscope, such as a transmission electron microscope (TEM), scanning electron microscope (SEM), or scanning transmission electron microscope (STEM), and is the average value of the thicknesses at those 30 points.

(Nonwoven fabric layer 30)
The nonwoven fabric layer 30 is a layer that ensures the ink-receiving ability of colored paints such as water-based stain paints and oil-based stain paints to penetrate into the voids in the fibers that form the nonwoven fabric layer 30, and exhibits stainability.The nonwoven fabric layer 30 partially has a filled portion A31 on the side of the surface 30a in the thickness direction of the layer where the adhesive layer 20 is provided, where the resin that forms the adhesive layer 20 has filled some of the voids in the fibers that form the nonwoven fabric layer 30, and a filled portion B33 on the side of the surface 30b in the thickness direction of the layer where the surface layer 40 is provided, where the cured product that forms the surface layer 40 has filled some of the voids in the fibers that form the nonwoven fabric layer 30.

Fibers that make up the nonwoven fabric layer 30 include thermoplastic resin fibers, natural fibers, recycled fibers, and semi-synthetic fibers, with thermoplastic resin fibers and recycled fibers being preferred from the standpoint of stainability. In this embodiment, these fibers can be used alone or in combination with multiple types.

Preferred examples of thermoplastic resin fibers include (meth)acrylic resins such as poly(meth)acrylate; polyvinyl acetal (butyral resin) such as polyvinyl butyral; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyolefin resins such as polyethylene and polypropylene; styrene resins such as polystyrene and α-methylstyrene; acetal resins such as polyoxymethylene; thermoplastic elastomers such as polyolefin thermoplastic elastomers, polystyrene thermoplastic elastomers, polydiene thermoplastic elastomers, polyurethane thermoplastic elastomers, polyester thermoplastic elastomers, and fluororesin thermoplastic elastomers; fluororesins such as vinyl chloride resins, polyurethane resins, and ethylene-tetrafluoroethylene copolymers, polyamide resins, polyimide resins, polylactic acid resins, polycarbonate resins, polyvinyl acetal resins, and liquid crystalline polyester resins. Of these thermoplastic resin fibers, considering dimensional stability, thermoplastic resin fibers made from resins such as polyester resin, polyolefin resin, and polyurethane resin are preferred, with thermoplastic resin fibers made from polyester resin and polyolefin resin being more preferred.

The thermoplastic resin that makes up the thermoplastic resin fiber may be a single type or a combination of multiple types. For example, it may be a composite fiber, such as a double-structure fiber in which the core is polyester resin and the sheath is polyolefin resin.

Natural fibers include fibers made from natural materials such as cotton, wool, and silk, regenerated fibers include rayon, cupra, and lyocell, and semi-synthetic fibers include triacetate and promix.

There are no particular restrictions on the fiber diameter of the fibers constituting the nonwoven fabric layer 30, but taking into consideration the feel in particular, the average fiber diameter is preferably 0.5 μm or more, more preferably 1 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. Nonwoven fabrics made of fibers having an average fiber diameter in this range tend to have a feel that closely resembles wood.
The average fiber diameter of the fibers constituting the nonwoven fabric can be measured by measuring the fiber widths (diameters) of 30 fibers present at any location in the nonwoven fabric using an electron microscope (300x magnification) and averaging the values obtained for each measurement result.

The fibers that make up the nonwoven fabric layer 30 can be formed, for example, by forming fleece using the spunbond method and then bonding the formed fleece using a thermal bond method, spunlace method (hydroentanglement method), or other method. Furthermore, nonwoven fabric layers 30 formed using these methods tend to have a texture that closely resembles wood.

The basis weight of the fibers constituting the nonwoven fabric layer 30 is not particularly limited, but from the viewpoint of obtaining the strength of the nonwoven fabric layer 30, it is preferably 10 g/ ^m2 or more, more preferably 15 g/ ^m2 or more, and the upper limit is preferably 40 g/m2 or ^less , more preferably 30 g/m2 or ^less , and even more preferably 20 g/ ^m2 or less.

There are no particular restrictions on the thickness of the nonwoven fabric layer 30, but taking into consideration the strength, mass, flexibility, and other physical properties of the recoat decorative sheet 1, it is preferably 30 μm or more, more preferably 50 μm or more, even more preferably 60 μm or more, and even more preferably 70 μm or more, with an upper limit of preferably 250 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, and even more preferably 100 μm or less.

(Filling section A31 and filling section B33)
On the surface 30a side of the nonwoven fabric layer 30 where the adhesive layer 20 is provided in the thickness direction within the layer, there is a filled section A31 in which a resin that forms the adhesive layer 20 is filled into some of the voids in the fibers, and on the other hand, on the surface 30b side where the surface layer 40 is provided in the thickness direction within the layer, there is a filled section B33 in which a cured material that forms the surface layer 40 is filled into some of the voids in the fibers.

In order to achieve the effect of obtaining stainability and surface characteristics, as well as improving the surface feel and transparency, the filling section A formed from the adhesive layer 20 and nonwoven fabric layer 30, and the filling section B formed from the surface layer 40 and nonwoven fabric layer 30, as well as the configuration of the surface layer 40 described above, also play an important role. In relation to the adhesive layer 20 and the surface layer 40, the nonwoven fabric layer 30 can be said to be a layer having two filling sections, filling sections A and B.

The filling portion A31 is formed by at least a portion of the resin forming the adhesive layer 20 penetrating into the nonwoven fabric layer 30, thereby achieving excellent adhesion between the paper base material 10 and the nonwoven fabric layer 30. In addition, by suppressing and protecting the paper base material 10 from the penetration of solvents (water, solvents, alcohol, etc.) contained in colored paints such as stain paints, the recoat decorative sheet as a whole is also water-resistant, in addition to the water-resistance as a surface characteristic.
On the other hand, the filling portion B33 is formed by at least a portion of the resin forming the surface layer 40 penetrating into the nonwoven fabric layer 30, thereby providing stainability as well as surface properties, and further providing a pleasant feel by maintaining good nap in the nonwoven fabric layer 30 together with the surface layer 40, and also suppressing a decrease in transparency due to the nap (surface irregularities) and refractive index caused by voids in the nonwoven fabric layer 30, thereby achieving designability through excellent transparency. Furthermore, deterioration of the paper substrate 10 due to penetration of solvents (water, solvents, alcohol, etc.) contained in colored paints such as stain paints can be suppressed, thereby providing water resistance for the recoat decorative sheet as a whole.

The filled portion A31 is a portion in which the resin that forms the adhesive layer 20 is filled into the gaps in the fibers that form the nonwoven fabric layer 30, and no gaps remain, so it does not have the ability to accept colored paint such as stain paint.
In the filled section B33, like the filled section A31, the voids in the fibers that form the nonwoven fabric layer 30 are filled with the hardened material that forms the surface layer 40, and no voids remain, so this is a section that does not have the ink-retentive properties to allow colored paints such as water-based stain paint and oil-based stain paint to penetrate.

In the recoatable decorative sheet 1 of this embodiment, the nonwoven fabric layer 30 partially has the above-mentioned filled portion A31 and filled portion B33. That is, the nonwoven fabric layer 30 needs to have the fiber portion 32 described below, which is the portion other than filled portion A31 and filled portion B33. Without the fiber portion 32, which is the portion other than the filled portions, these filled portions will have no voids and will not have the ability to accept colored paint such as stain paint, and therefore will not be able to achieve stainability.

In Figures 1 and 2, filled portions A31 and B33 are shown schematically as being layered, but because the shapes of the fibers constituting nonwoven fabric layer 30 and the shapes of the voids in the fibers are not uniform, it is believed that they do not necessarily form uniform layers as shown in the figures. Considering that coloring is achieved by the penetration of a colored paint such as a stain paint, it is believed that, for example, filled portions A31 and B33 shown in the figures are scattered within a certain range in the thickness direction of nonwoven fabric layer 30, in which the voids in the fibers constituting nonwoven fabric layer 30 are filled with the resin that forms adhesive layer 20 and the cured product that forms surface layer 40, respectively, and the remaining portions are scattered as fiber portions 32, described below.

(Fiber part 32)
As described above, the recoat decorative sheet of this embodiment is a layer that partially has the filled portion A31 and the filled portion B33, and therefore naturally has the portion other than these filled portions, i.e., the fiber portion 32. By having the fiber portion 32, the recoat decorative sheet of this embodiment ensures ink-receiving properties that allow a colored paint such as a stain paint to penetrate into the voids in the fibers, thereby exhibiting stainability.

The form of the fiber portion 32 is not particularly limited, as long as it is not filled with the cured material that forms the adhesive layer 20 and the surface layer 40 and voids remain. Examples include a form in which the resin that forms the adhesive layer 20 and the surface layer 40 does not penetrate into the voids in the fibers that form the nonwoven fabric layer 30 at all, leaving the fibers intact and with voids in the fibers; or a form in which the resin that forms the adhesive layer 20 and the surface layer 40 penetrates to some extent, but the fibers are merely coated with these resins, with voids in the coated resin. In the recoatable decorative sheet of this embodiment, either form of the fiber portion 32 is acceptable.

The fiber portion 32 is the portion not filled with the resin that forms the adhesive layer 20 and the surface layer 40, i.e., the portion other than the filled portion A31 and the filled portion B33. In Figures 1 and 2, the fiber portion 32 is shown schematically as existing in a layer; however, as previously mentioned, the filled portion A31 and the filled portion B33 are scattered within a certain range in the thickness direction of the nonwoven fabric layer 30, and therefore, strictly speaking, they are not considered to exist in a layer. Therefore, the fiber portion 32 is considered to be scattered within a certain range in the thickness direction of the nonwoven fabric layer 30, as shown as the fiber portion 32 in Figures 1 and 2.

One method for partially providing the nonwoven fabric layer 30 with the filled portions A31 and B33 is to adjust the amount of resin composition applied when forming the adhesive layer 20 and the amount of resin composition applied when forming the surface layer 40. For example, increasing the amount of resin composition applied when forming the adhesive layer 20 increases the proportion of filled portions A31 in the nonwoven fabric layer 30. On the other hand, increasing the amount of composition applied when forming the surface layer 40 increases the proportion of filled portions B33 in the nonwoven fabric layer 30. Furthermore, increasing the amount of composition applied when forming the adhesive layer 20 and the surface layer 40 decreases the proportion of fiber portions 32 in the nonwoven fabric layer 30, and decreasing the amount of composition applied increases the proportion of fiber portions 32 in the nonwoven fabric layer 30.
In this embodiment, the desired state of the nonwoven fabric layer 30 can be obtained by adjusting, for example, the amount of application.

(Adhesive layer 20)
The adhesive layer 20 is a layer provided on at least one side of the paper substrate 10, and is a layer provided for bonding the paper substrate 10 to the nonwoven fabric layer 30. Furthermore, by providing the adhesive layer 20 so that it has the filling portion A, in addition to the adhesion between the paper substrate 10 and the nonwoven fabric layer 30, it is possible to suppress and protect the paper substrate 10 from the penetration of solvents (water, solvents, alcohol, etc.) contained in the stain paint, and therefore the recoat decorative sheet as a whole is provided with water resistance in addition to water resistance as a surface property.

The adhesive used in the adhesive layer 20 can be any adhesive made of various resins, without any particular limitations. Examples of resins that form the adhesive include urethane resins, polyolefin resins, acrylic resins, and epoxy resins. These resins can be used alone or in combination. Among these, urethane resins and polyolefin resins are preferred, and urethane resins are even more preferred. The use of these resins can provide excellent adhesion while suppressing the penetration of the solvent (solvent, alcohol) of the stain paint applied to the nonwoven fabric layer 30 into the paper substrate 10, improving the surface properties of the recoat decorative sheet 1, such as water resistance, and also making it easier to maintain physical properties such as strength, mass, and flexibility.
The nonwoven fabric layer 30 includes a filled portion A31 and a filled portion B33 filled with the resin that forms the adhesive layer 20 and the resin that forms the surface layer 40, and also includes a fiber layer 32 that is not filled with either resin, but also includes a portion where the resin that forms the adhesive layer and the resin that forms the surface layer come into contact. Therefore, if the adhesive used in the adhesive layer 20 is the same type of resin as the resin used to form the surface layer 40, i.e., a urethane resin, is used, the adhesive properties can be further improved. From this perspective, urethane resin is particularly preferred as the adhesive used in the adhesive layer 20.

As the urethane resin, either a thermoplastic urethane resin or a curable urethane resin may be used, and from the viewpoint of adhesiveness in particular, it is preferable to use a curable urethane resin.
The curable polyurethane resin may be either a two-component curing type or a one-component curing type, and from the viewpoint of adhesiveness, a two-component curing type polyurethane resin is preferred.
The two-component curing polyurethane resin is a polyurethane resin that contains a polyol as a main component and an isocyanate as a crosslinking agent (curing agent), and the polyol and isocyanate may be appropriately selected from the polyol compounds and isocyanate curing agents described above as being used to form the surface layer.
Thermoplastic polyurethane resin is a copolymer obtained by copolymerizing monomers with urethane bonds formed by condensation of an isocyanate group and a compound having a hydroxyl group such as an alcohol group.

Examples of polyolefin resins include those containing one or more monoolefins such as ethylene, propylene, butene, pentene, hexene, heptene, octene, and 4-methyl-1-pentene as monomer units, and further include those containing monomer units other than monoolefins, such as alicyclic olefins such as cyclopentene and cyclohexene, linear or cyclic polyenes such as 1,4-hexadiene, 1,5-hexadiene, divinylbenzene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, and 5-vinyl-2-norbornene, and aromatic vinyl compounds such as styrene and substituted styrene.
From the viewpoint of adhesion to the paper substrate 10 and the nonwoven fabric layer 30, the polyolefin resin is preferably a polyethylene resin containing ethylene as a monomer unit.

When a urethane resin or polyolefin resin is used, the proportion of the urethane resin or polyolefin resin relative to the total resin forming the adhesive layer 20 is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably 100%.

In this embodiment, the resin forming the adhesive layer 20 can be used as a resin composition containing an appropriate amount of additives, such as UV absorbers, weathering agents such as light stabilizers, extender pigments, solvents, stabilizers, and plasticizers. In other words, the adhesive layer 20 can be formed from a resin composition containing additives in addition to the resin.

The thickness of the adhesive layer 20 cannot be specified as a fixed value because it can vary depending on the materials of the paper base material 10 and the nonwoven fabric layer 30, the thickness of the nonwoven fabric layer 30, etc., but from the standpoint of achieving, for example, adhesion between the paper base material 10 and the nonwoven fabric layer 30, forming the filling portion A31, the filling portion B33, and the fiber portion 32 in a balanced manner, improving stainability and surface characteristics, and further improving transparency, etc., the total thickness of the adhesive layer 20 and the filling portion A31 is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and still more preferably 8 μm or more, with the upper limit being preferably 25 μm or less, more preferably 20 μm or less, even more preferably 18 μm or less, and still more preferably 15 μm or less. In addition, being within the above range also improves the water resistance of the recoat decorative sheet as a whole.
The total thickness of the adhesive layer 20 and the filling portion A31, like the total thickness of the surface layer 30 and the filling portion B33, is the average value of the thicknesses measured at any 30 points on a cross-sectional image taken using various electron microscopes, such as a transmission electron microscope (TEM), a scanning electron microscope (SEM), or a scanning transmission electron microscope (STEM).

(Paper base material 10)
From the viewpoints of reducing the environmental impact and reducing costs, a paper substrate is used for the recoat decorative sheet 1 of this embodiment. The paper substrate 10 functions as a support for providing other layers in the recoat decorative sheet 1 of this embodiment.
Examples of substrates that can be used for the paper substrate 10 include fine paper, tissue paper, linter paper, kraft paper, reinforced inter-paper paper, resin-impregnated paper, wallpaper backing paper, and flame-retardant paper obtained by mixing or impregnating a flame retardant into any of these papers. These materials may be used alone, or may be combined in any combination to form a laminate, such as a laminate of papers.
The paper base material 10 may contain additives such as flame retardants, inorganic agents, dry strength agents, wet strength agents, colorants, sizing agents, and fixing agents as needed.

There are no particular restrictions on the thickness of the paper substrate 10, but taking into consideration the durability and ease of handling of the decorative sheet, the basis weight is preferably in the range of 20 g/m2 or ^more and 150 g/ ^m2 or less, more preferably in the range of 25 g/m2 or ^more and 120 g/ ^m2 or less, even more preferably in the range of 35 g/ ^m2 or more and 100 g/m2 or ^less , and even more preferably in the range of 40 g/m2 or ^more and 60 g/ ^m2 or less.

(Decorative layer 50)
From the viewpoint of improving design, the decorative sheet for recoat 1 of this embodiment preferably has a decorative layer 50. The decorative layer 50 may be provided between the paper substrate 10 and the nonwoven fabric layer 30, and is preferably provided between the paper substrate 10 and the adhesive layer 20.
The decorative layer 50 may be a layer consisting of only an all-over colored layer 51 provided to cover the entire surface, or a layer consisting of only a patterned layer 52 provided to cover a portion of the decorative layer 50 and form a pattern, or a layer combining the all-over colored layer 51 and the patterned layer 52. These layer configurations may be determined according to the desired pattern.

The pattern imparted by the decorative layer 50 is not particularly limited and may be selected as desired, and examples thereof include wood grain patterns, marble patterns (e.g., travertine marble patterns), stone patterns imitating the surface of rock such as the cleavage plane of a granite slab, fabric patterns imitating cloth grain or fabric-like patterns, leather (leather grain) patterns expressing leather grain, tiled patterns, brickwork patterns, hairline patterns, linear grooves, pear-skin patterns, sand patterns, letters, symbols, geometric patterns, and patterns combining these, such as marquetry and patchwork. Further examples of patterns combining these include artificial stone patterns made by mixing crushed stone such as marble with white cement, hardening it, and polishing it to resemble marble, i.e., so-called artificial marble patterns.
Although consumer demands for designs change with trends and the like, wood grain patterns remain popular, and so a wood grain pattern is preferred for the pattern of the decorative recoat sheet 1 of this embodiment. Wood grain patterns include straight grain patterns, cross grain patterns, figured grain patterns, end grain patterns, etc., and any of these may be used.

To form the decorative layer 50, it is preferable to use a resin composition containing at least a binder resin and colorants such as pigments and dyes, and an appropriate mixture of other components that can be used as desired, such as matting agents, extender pigments, stabilizers, solvents, and weathering agents such as UV absorbers and light stabilizers. In other words, the decorative layer 50 is a layer that contains at least a binder resin and colorants such as pigments and dyes, and can also contain other components that can be used as desired as described above.

There are no particular restrictions on the binder resin, and preferred examples include urethane resin, acrylic polyol resin, acrylic resin, polyester resin, alkyd resin, amide resin, butyral resin, styrene resin, urethane-acrylic copolymer, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-acrylic copolymer resin, nitrocellulose resin (nitrocellulose), and cellulose acetate resin. Curable resins may also be used, such as two-component curable resins that use various polyols, such as acrylic polyols, as the base resin and various isocyanates as the curing agent. These may be used alone or in combination.

Colorants can be appropriately selected from known pigments, such as inorganic pigments such as titanium white, lead white, carbon black, iron black, yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine blue, and cobalt blue; organic pigments or dyes such as quinacridone red, isoindolinone yellow, nickel azo complexes, and phthalocyanine blue; metallic pigments consisting of scaly flakes of aluminum, brass, etc.; and pearlescent pigments consisting of scaly flakes of titanium dioxide-coated mica, basic lead carbonate, etc.

Furthermore, from the viewpoint of further improving the design, it is preferable that the decorative layer 50 contains a matting agent among the other components that may be used as desired.
Examples of the matting agent include inorganic fillers such as silica, clay, heavy calcium carbonate, light calcium carbonate, precipitated barium sulfate, calcium silicate, synthetic silicate, and silicate fine powder; and organic fillers such as acrylic resin, urethane resin, nylon resin, polypropylene resin, and urea resin.

By including a matting agent in the decorative layer 50, the decorative layer has a lower gloss, which makes it possible to create a design that has a visually uneven appearance due to differences in gloss.
For example, in the wood grain pattern exemplified as a preferred pattern, the wood grain pattern includes a lower gloss (matte or low gloss) vessel portion, a higher gloss (glossy or high gloss) spring wood portion, and an even higher gloss autumn wood portion (shiny portion). In the decorative layer 50, a highly decorative pattern can be formed by combining multiple pattern layers 52, such as a pattern layer forming a lower gloss vessel portion, a pattern layer forming a higher gloss spring wood portion, and a pattern layer forming an even higher gloss autumn wood portion. In this case, for example, by not including a matting agent in the full-colored layer 51 or by including a lower matting agent content than in the pattern layer 52, the difference in gloss from the pattern layer 52 can be increased, thereby improving the decorativeness.

There are no particular restrictions on the thickness of the decorative layer 50, but from the perspective of improving design, it is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, with the upper limit being preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 7.5 μm or less. When the decorative layer 50 is formed from two or more layers, it is preferable that the total thickness of the layers be within the above range.

(Method for manufacturing decorative sheet for recoating)
The method for producing the recoatable decorative sheet 1 of this embodiment will be described by taking as an example the recoatable decorative sheet 1 shown in FIG. 2, which is one of the preferred embodiments of the recoatable decorative sheet 1 of this embodiment.
The recoatable decorative sheet 1 of this embodiment shown in Figure 2 can be manufactured through step 1 of providing a decorative layer 50 on a paper base material 10, step 2 of providing an adhesive layer 20 on the decorative layer 50, step 3 of providing a nonwoven fabric layer 30 and a filling portion A31 on the adhesive layer 20, and step 4 of applying a resin composition that forms a surface layer 40 to the surface of the nonwoven fabric layer 30, and forming a filling portion B33 together with the surface layer 40.

Step 1 is to provide a decorative layer 50 on a paper substrate 10 .
The decorative layer 50 is preferably formed by gravure printing, silk screen printing, gravure offset printing, flexographic printing, ink jet printing, etc. using the resin composition used to form the decorative layer 50, and it is more preferable to use gravure printing for large lots and ink jet printing for small lots.

Step 2 is a step of providing an adhesive layer 20 on the decorative layer 50 .
For example, a resin composition that is appropriately selected from the resins exemplified as resins that can form the adhesive layer 20, preferably containing a urethane resin, is applied onto the decorative layer 50 to form the adhesive layer 20. In this case, the method for applying the resin composition may be selected from any of the known methods exemplified as the method for applying the resin composition to the decorative layer 50.

In this case, the amount of resin composition applied (dry base) to form the adhesive layer 20 is preferably 2 g/m2 or more, more preferably 5 g/ ^m2 or more, even more preferably 8 g/m2 or more, and still more preferably 10 g/m2 or more, from the viewpoint of obtaining excellent adhesion, forming the filling portion ^A31 , the filling portion B33, and the fiber ^{portion 32} in a balanced manner, and improving stainability and transparency, and the upper limit is preferably 50 g/ ^m2 or ^less , more preferably 45 g/m2 or ^less , even more preferably 40 g/m2 or ^less , and still more preferably 30 g/ ^m2 or less.

Step 3 is a step of providing the nonwoven fabric layer 30 and the filling portion A31 on the adhesive layer 20.
The nonwoven fabric layer 30 and the filling portion A31 are formed, for example, by forming an adhesive layer 20 by applying a resin composition, placing a nonwoven fabric on top of this, and then dry laminating the adhesive layer 20 to form the nonwoven fabric layer 30, and the resin composition used to form the adhesive layer is filled into some of the voids in the nonwoven fabric to form the filling portion A31.

In this case, the thickness of the adhesive layer-forming resin is preferably 10% or more, more preferably 12% or more, and even more preferably 14% or more of the thickness of the nonwoven fabric layer 30, from the perspective of obtaining excellent adhesion between the paper base material 10 and the nonwoven fabric layer 30, forming the filling portion A31, the filling portion B33, and the fiber portion 32 in a balanced manner, improving stainability and transparency, and further improving transparency, tactile feel, etc., and the upper limit is preferably 25% or less, more preferably 23% or less, and even more preferably 20% or less.

Step 4 is a step of applying a composition for forming the surface layer 40 to the surface of the nonwoven fabric layer 30, thereby forming the surface layer 40 and the filling portion B33.
The composition that forms the surface layer 40 may be applied by selecting any of the known methods exemplified above as methods for applying the resin composition in the decorative layer 50. When forming the surface layer 40, the amount of composition to be applied may be determined mainly taking into consideration the thickness of the surface layer 40 as well as the balance between the filler B33, the fiber portion 32, and the filler A31 in the nonwoven fabric layer 30. From the viewpoint of forming the filler A31, the filler B33, and the fiber portion 32 in a balanced manner and improving the surface characteristics as well as stainability, as well as transparency and tactile feel, the amount of composition to be applied is typically 2 g/m ² or more, preferably 4 g/m ² or more, and more preferably 6 g/m ² or more, with the upper limit being preferably 20 g/m ² or less, more preferably 15 g/m ² or less, and even more preferably 12 g/m ² or less.

The above steps allow for the production of a preferred embodiment of the recoatable decorative sheet 1 shown in Figure 2, which comprises, in order, a paper base material 10, a decorative layer 50, an adhesive layer 20, a nonwoven fabric layer 30 (filler section A31, fiber section 32, filler section B33), and a surface layer 40.

[Method for coloring decorative sheets]
The method for coloring a decorative sheet of this embodiment is characterized in that a colored paint is applied to the surface layer side of the decorative sheet for recoat of this embodiment, thereby coloring the nonwoven fabric layer. Examples of the colored paint include stain paint (water-based or oil-based).
The recoat decorative sheet 1 of this embodiment has a nonwoven fabric layer 30, which ensures the adhesion of colored paints such as water-based stain paints and oil-based stain paints, allowing them to penetrate into the voids in the fibers. By applying colored paint using the coloring method of this embodiment, the colored paint is retained in the fiber portion 32 of the nonwoven fabric layer 30 as well as on the outermost surface of the recoat decorative sheet, resulting in a decorative sheet exhibiting a design created by the colored paint.

Next, the present invention will be explained in more detail using examples, but the present invention is not limited to these examples in any way.

(Evaluation method)
The decorative sheets obtained in each of the Examples and Comparative Examples were evaluated as follows.
<Evaluation of Staynability>
The decorative sheets obtained in each Example and Comparative Example were cut to dimensions of 200 mm x 300 mm, and an aqueous stain ("W Stain (trade name)" manufactured by Osaka Paint Industries Co., Ltd.) or an oil-based stain ("WOODFINISH (trade name)" manufactured by MINWAX Co., Ltd.) was uniformly applied and allowed to dry. After that, a 25 mm wide cellophane adhesive tape ("Cellotape (registered trademark)" manufactured by Nichiban Co., Ltd.) was applied to the stained area and then peeled off, and the condition of the stain was visually evaluated according to the following criteria to assess stainability. In this evaluation, a rating of A is a pass.
A: No peeling was observed for either the water-based stain or the oil-based stain.
B: Peeling was observed for the water-based stain.
C: Peeling was observed for both the water-based stain and the oil-based stain.

<Evaluation of surface properties (water resistance)>
The decorative sheets obtained in each Example and Comparative Example were cut to a size of 100 mm x 100 mm, water-soaked absorbent cotton was placed on the surface of the sheet, and the absorbent cotton was covered with a cap and left for 24 hours. After that, the cap was removed and the water was wiped off, and the appearance of the surface was visually evaluated according to the following criteria to evaluate the surface characteristics (water resistance). In this evaluation, an A rating is a pass.
A: No change in appearance was observed.
B: Slight whitening was observed on the surface.
C: Significant whitening was observed on the surface.

Example 1
A printing paper (HPT30 (product number) manufactured by Hokuetsu Kishu Paper Co., Ltd., thickness: 60 μm, basis weight: 45 g/ ^m2 ) was prepared as the paper substrate, and a decorative layer exhibiting a wood grain pattern (thickness: 2-6 μm) was formed on the printing paper by gravure printing using an ink containing an acrylic resin as a binder and a pigment (an ink containing an acrylic resin as a binder and carbon black as a pigment). Next, a resin composition for forming an adhesive layer (urethane resin, base: polyester polyol (Seikabond E-295NTL-D50 (product name) manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), and an isocyanate curing agent (Seikabond C-55 (product name) manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) was applied by gravure printing to form an adhesive layer (thickness: 3 μm) on the decorative layer.
Separately, a nonwoven fabric made of rayon fibers (product number "3016", manufactured by Kinsei Paper Co., Ltd., thickness: 80 μm, basis weight: 17 g/ ^m2 ) was prepared, and the paper base material on which the decorative layer and adhesive layer were formed was dry laminated with the nonwoven fabric to obtain a laminate having a paper base material, a decorative layer, an adhesive layer, and a nonwoven fabric layer consisting of filling portion A and a fiber portion.
Next, a composition containing 100 g of acrylic polyol compound 1 (hydroxyl value: 41 mg KOH/g) and 5 g of an isocyanate curing agent (hexamethylene diisocyanate, isocyanate group content: 19% by mass) was applied to the nonwoven fabric layer side of the laminate at a coating amount of 12 g/ ^m2 (dry basis) to form a filling section B and a surface layer, and the laminate was cured at 70°C for 48 hours to obtain a recoatable decorative sheet having a paper base material, a decorative layer, an adhesive layer, a nonwoven fabric layer consisting of filling section A, a fiber section and filling section B, and a surface layer.
The resulting decorative recoat sheet was evaluated by the above-mentioned methods, and the results are shown in Table 1.

Example 2
A recoatable decorative sheet was obtained in the same manner as in Example 1, except that in the composition used to form the surface layer in Example 1, acrylic polyol compound 1 was changed to acrylic polyol compound 2 (hydroxyl value: 24 mg KOH/g) and the amount of isocyanate curing agent used was changed from 5 g to 3 g.
The resulting decorative recoat sheet was evaluated by the above-mentioned methods, and the results are shown in Table 1.

(Comparative Examples 1 to 4)
A decorative sheet was obtained in the same manner as in Example 1, except that the amounts of acrylic polyol compound 1 and isocyanate curing agent used in the composition used to form the surface layer were changed as shown in Table 1.
The decorative sheet obtained was evaluated by the above-mentioned methods, and the results are shown in Table 1.

From the results of the examples, it was confirmed that the recoatable decorative sheet of this embodiment is excellent in surface properties such as water resistance as well as stainability.
On the other hand, the decorative sheet of Comparative Example 1 had a high content of residual hydroxyl groups and an excessively high affinity for moisture on the surface of the surface layer, resulting in poor water resistance. The decorative sheets of Comparative Examples 2 and 3 also had a low content of residual hydroxyl groups, and the decorative sheet of Comparative Example 3 also had a molar ratio (C _NCO /C _OH ) of less than 0.20, resulting in poor stainability and/or surface properties.

The decorative sheet of Comparative Example 4 had an appropriate content of residual hydroxyl groups, but the molar ratio ( _CNCO / _COH ) was less than 0.20, resulting in poor surface properties (water resistance).
From the above results, it was confirmed that unless both the content of residual hydroxyl groups and the molar ratio (C _NCO /C _OH ) are satisfied, it is not possible to achieve both stainability and surface properties.

The recoat decorative sheet of this embodiment is not only stainable but also has excellent surface properties such as water resistance, making it suitable for applications requiring repainting with a colored paint such as a stain paint, such as interior or exterior building components such as walls, ceilings, and floors, fittings and fixtures such as window frames, doors, handrails, baseboards, moldings, and other fixtures, as well as decorative surface panels for kitchen equipment, furniture, or cabinets for low-voltage and office equipment, and as a layer constituting the interior or exterior components of vehicles.

1: Recoatable decorative sheet 10: Paper substrate 20: Adhesive layer 30: Nonwoven fabric layer 30a: Surface of nonwoven fabric layer on which adhesive layer is provided 30b: Surface of nonwoven fabric layer on which surface layer is provided 31: Filling section A
32: Fiber portion 33: Filling portion B
40: Surface layer 50: Decorative layer 51: Full colored layer 52: Design layer

Claims (9)

A decorative sheet for recoat comprising , in order, a paper substrate, an adhesive layer, a nonwoven fabric layer, and a surface layer made of a cured product of a composition containing a polyol compound having a hydroxyl group in its molecule and an isocyanate curing agent,
the nonwoven fabric layer partially has a filled portion A on the side of the layer in the thickness direction where the adhesive layer is provided, in which a resin forming the adhesive layer is filled into some of the voids of the fibers constituting the nonwoven fabric layer, and a filled portion B on the side of the layer in the thickness direction where the surface layer is provided, in which the cured product is filled into some of the voids of the fibers constituting the nonwoven fabric layer,
the outermost surface of the decorative sheet for recoat has at least partial voids between the fibers constituting the nonwoven fabric layer;
the content of residual hydroxyl groups contained in the surface layer is 0.25% by mass or more and 1.10% by mass or less,
a ratio (C _NCO /C _OH ) of the amount of isocyanate groups C _NCO (mmol) in the isocyanate curing agent to the amount of hydroxyl groups C _OH (mmol) in the polyol compound is 0.20 or more;
Decorative sheet for recoating. The decorative sheet for recoating according to claim 1, wherein the fibers are at least one type of fiber selected from thermoplastic resin fibers and recycled fibers. The decorative sheet for recoat according to claim 1 or 2, wherein the fibers are cellulose resin fibers. The decorative sheet for recoat according to any one of claims 1 to 3, wherein the resin forming the adhesive layer is at least one resin selected from urethane resins and polyolefin resins. The decorative sheet for recoat according to any one of claims 1 to 4, wherein the polyol compound is one or more selected from acrylic polyol, polyester polyol, polyether polyol, and polycarbonate polyol. The decorative sheet for recoat according to any one of claims 1 to 5, wherein the isocyanate curing agent is a polyvalent isocyanate compound. The decorative sheet for recoat according to any one of claims 1 to 6, further comprising a decorative layer between the paper substrate and the adhesive layer. The decorative sheet for recoat according to claim 7, wherein the decorative layer has a wood grain pattern. A method for coloring a decorative sheet, comprising applying a colored coating to the surface of the surface layer of the recoatable decorative sheet according to any one of claims 1 to 8, thereby coloring the nonwoven fabric layer.