JP7704800B2 - Curable composition, cured product thereof, and laminate - Google Patents

Description

The present invention relates to a curable composition, a cured product thereof, and a laminate.

Traditionally, resin-impregnated decorative boards (hereafter referred to as "decorative boards") have been used as surface materials to improve the design and durability of building materials for homes and furniture. Decorative boards are obtained by integrating resin-impregnated decorative paper (hereafter referred to as "decorative paper") impregnated with melamine, a thermosetting resin, with a substrate (such as a wood substrate or inorganic material).

The manufacturing method of decorative paper includes, for example, (1) a method in which impregnated paper such as porous base paper is immersed in a tank filled with melamine resin to impregnate the paper with melamine resin to obtain decorative paper, and then the decorative paper is layered on the top of a substrate and thermo-compressed at low pressure (low-pressure melamine method); and (2) a method in which only melamine resin-impregnated decorative paper and phenolic resin-impregnated decorative paper are layered and thermo-compressed at high pressure (high-pressure melamine method). These melamine decorative boards have high top surface hardness, excellent stain resistance, abrasion resistance, heat resistance, water resistance, and scratch resistance, and therefore the decorative boards obtained by the low-pressure melamine method are used for furniture materials and interior materials, and the decorative boards obtained by the high-pressure melamine method are thin and therefore used for furniture and door surfaces, shelves, counter surfaces, etc. From the viewpoint of obtaining a decorative board with excellent surface smoothness and design, a decorative board in which a top coat layer is further provided on the surface of the decorative paper after the decorative paper is manufactured has also been proposed (for example, Patent Documents 1 and 2, etc.).

JP 2018-140629 A JP 2022-172800 A Patent No. 7212425

However, the manufacturing of decorative boards has a problem in that a large amount of thermal energy is consumed during the manufacturing process. That is, decorative boards are manufactured by impregnating, drying, and thermocompressing (180°C) petroleum-derived resins such as melamine resin and phenolic resin as described above, and the amount of thermal energy consumed during the manufacturing process is enormous. For this reason, there is a demand for curable materials that can manufacture decorative paper and decorative boards with less thermal energy than conventional thermosetting resins. In addition, because thermosetting resins such as melamine resin have a high proportion of petroleum-derived components, there is also a demand for environmentally friendly curable materials with fewer petroleum-derived components. In response to this problem, for example, Patent Document 3 proposes a manufacturing device for decorative boards that can reduce power consumption in the manufacturing process.

The objective of the present disclosure is to provide a curable composition that can be applied to decorative paper and decorative boards, and that can be cured with less thermal energy than conventional curable compositions, a cured product thereof, and a laminate that contains one or more of these.

After extensive research, the inventors of the present application have found that the above-mentioned problems can be solved by making the curable component a dual-cure material capable of both photocuring (UV curing, electron beam curing, etc.) and heat curing, and by controlling the ratio of heat-curable functional groups and photocurable functional groups in the curable component. Even more surprisingly, they have found that this curable material can be cured at a lower temperature than conventional materials, and can be applied to all of the impregnating resin, topcoat layer, and adhesive layer to the substrate of decorative paper or decorative board. Furthermore, since the above-mentioned effects can be maintained even if a biomass-derived material is selected as the curable component, it is also possible to make an environmentally friendly curable material with a low ratio of petroleum-derived components.

That is, the present invention has the following aspects.
[1] A composition comprising a curable component and a photopolymerization initiator,
The curable component is
a polyisocyanate component (A) containing at least two isocyanate groups;
and a polyol component (B) containing at least two hydroxyl groups,
The curable composition further comprises one or more components selected from the component (A) and the component (B), which further comprises at least one (meth)acryloyl group, and/or further comprises a (meth)acrylate component (C) comprising at least one (meth)acryloyl group.
[2] The curable composition according to [1], wherein one or more components selected from the component (A) and the component (B) further contain at least one (meth)acryloyl group.
[3] The curable component contains the component (C),
The curable composition according to [1] or [2], wherein the component (C) contains a hydroxyl group-containing (meth)acrylate (C2) containing at least one (meth)acryloyl group and a hydroxyl group.
[4] The curable composition according to any one of [1] to [3], wherein the component (B) contains a (meth)acryloyl group-containing polyol (B2) having at least one (meth)acryloyl group and at least two hydroxyl groups.
[5] The curable composition according to any one of [1] to [4], wherein the ratio of the biomass-derived component to the total mass of the curable component is 10 mass% or more.
[6] The curable composition according to any one of [1] to [5], wherein the average hydroxyl equivalent of the component (B) is 30 to 5,000.
[7] The curable composition according to any one of [1] to [6], wherein the curable component has an isocyanate index (average isocyanate group equivalent/average hydroxyl group equivalent) of 0.01 to 2.0.
[8] A cured product of the curable composition according to any one of [1] to [7].
[9] A laminate comprising a layer containing one or more layers selected from the curable composition according to any one of [1] to [7] and the cured product according to [8].
[10] The laminate according to [9], which is a resin-impregnated decorative paper or a resin-impregnated decorative board.

The present disclosure provides a curable composition that can be cured with less thermal energy than conventional methods, a cured product thereof, and a laminate that contains one or more of these.

FIG. 11 is a cross-sectional view showing an example of a decorative board, which is one aspect of a laminate according to a third embodiment.

An embodiment of the present disclosure will be described in detail below. The present disclosure is not limited to the following embodiment, and can be implemented by making appropriate modifications within a range that does not impair the effects of the present disclosure.
Each configuration and combination thereof in each embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible as appropriate within the scope of the present disclosure. The present disclosure is not limited to the embodiments, but is limited only by the claims.
Each feature disclosed herein may be combined with any other feature disclosed herein.
In cases where a specific description given for one embodiment also applies to other embodiments, the description may be omitted in the other embodiments. In this disclosure, the expression "X to Y" regarding a numerical range means "X or more and Y or less."

[Curable composition]
A first embodiment of the present disclosure relates to a curable composition comprising a curable component and a photopolymerization initiator, the curable component comprising a polyisocyanate component (A) containing at least two isocyanate groups and a polyol component (B) containing at least two hydroxyl groups, and one or more components selected from the components (A) and (B) further comprising at least one (meth)acryloyl group and/or further comprising a (meth)acrylate component (C) containing at least one (meth)acryloyl group. According to the first embodiment, a curable composition that can be cured with less thermal energy than conventional compositions can be provided.

<Curable component>
The curable composition according to the first embodiment includes a polyisocyanate component (A) containing at least two isocyanate groups and a polyol component (B) containing at least two hydroxyl groups, and one or more components selected from the component (A) and the component (B) further include at least one (meth)acryloyl group, and/or further include a (meth)acrylate component (C) containing at least one (meth)acryloyl group.

(Polyisocyanate Component (A))
The curable component includes a polyisocyanate component (A) (hereinafter, sometimes referred to as "component (A)") having at least two isocyanate groups. Here, the "polyisocyanate component (A)" includes a polyisocyanate having at least two isocyanate groups (e.g., polyisocyanate (A1) and/or (meth)acryloyl group-containing polyisocyanate (A2) described below) in an amount of 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, based on the total mass of component (A).

In one embodiment, the number of isocyanate groups in component (A) (hereinafter referred to as "isocyanate group number (a)") may be 2 to 4, or 2 to 3.5. If the isocyanate group number (a) is within the above range, it is easier to balance photocuring and thermal curing, and it is easier to obtain a curable composition that can be cured with less thermal energy. Note that, when component (A) contains polyisocyanate (A1) and (meth)acryloyl group-containing polyisocyanate (A2) described later, the isocyanate group number (a) is the total number of isocyanate groups in polyisocyanates (A1) and (A2).

The number (a) of isocyanate groups in component (A) can be calculated from the following formula (1).
Number of isocyanate groups (a) = (number average molecular weight (Mn) of component (A)) x (isocyanate group concentration (mass%) in component (A)) / 4202 ... (1)
In formula (1), the number average molecular weight (Mn) of component (A) can be measured using GPC with a solvent of THF, a column temperature of 40° C., and a standard substance of polyethylene oxide. The isocyanate group concentration in component (A) can be analyzed by, for example, IR (infrared spectroscopy) or the following titration method.

Measurement of isocyanate group concentration: Measurement of the isocyanate group concentration (mass%) by titration is carried out as follows: The measurement is carried out using a 100 mL glass flask while stirring with a stirrer.
First, a blank value is measured as follows.
15 mL of a THF solution of dibutylamine (0.1 N) is added to 15 mL of THF. Three drops of bromophenol blue (1% by mass diluted in methanol) are added to color the solution blue, and the solution is then titrated with an aqueous HCl solution having a normality of 0.1 N. The titration amount of the aqueous HCl solution at the point when a color change is observed is designated as Vb (mL).
Next, the actual isocyanate group concentration is measured. First, a sample is weighed out to Ws (g), dissolved in 15 mL of THF, and 15 mL of a THF solution of dibutylamine (0.1 N) is added. After confirming that the sample has been dissolved, three drops of bromophenol blue (1% by mass diluted with methanol) are added to color the sample blue, and then titrated with an aqueous HCl solution having a normality of 0.1 N. The titration amount of the aqueous HCl solution at the time when a color change is observed is designated as Vs (mL).
The isocyanate group concentration in the sample is calculated using the following formula (2).
Isocyanate group concentration (mass%)=[(Vb−Vs)×1.005×0.42]/Ws (2)
When a commercially available product is used as component (A), the aforementioned isocyanate group concentration and number average molecular weight may be the nominal values published by the manufacturer.

In one embodiment, the isocyanate group concentration in component (A) may be 5 to 30% by mass, 10 to 30% by mass, 15 to 30% by mass, or 20 to 30% by mass. The number average molecular weight (Mn) of component (A) may be 100 to 1,000, 150 to 1,000, 150 to 800, or 450 to 700. When the number average molecular weight (Mn) and isocyanate group concentration of component (A) are within the above ranges, the curability is likely to be good.

In one embodiment, the average isocyanate group equivalent of component (A) may be 80 to 1,000 g/mol, 90 to 750 g/mol, or 100 to 500 g/mol. When the average isocyanate group equivalent of component (A) is within the above range, the curability tends to be good. The "average isocyanate group equivalent" (hereinafter sometimes referred to as "NCO equivalent") may be a value measured according to the standard of JIS K 1603-1, or a value calculated from the following formula (3).
NCO equivalent=(molecular weight of isocyanate group (NCO group) (42))/(isocyanate group concentration (mass%))×100 (3)

Component (A) may contain one or more polyisocyanates (A1) selected from polyisocyanate monomers and polyisocyanate derivatives having at least two isocyanate groups.

(Polyisocyanate (A1))
Examples of the polyisocyanate monomer contained in the polyisocyanate (A1) (hereinafter, sometimes referred to as "component (A1)") include polyisocyanates such as aromatic polyisocyanates, araliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

Aromatic polyisocyanates include, for example, bifunctional aromatic diisocyanates such as tolylene diisocyanate (2,4- or 2,6-tolylene diisocyanate, or a mixture thereof) (TDI), phenylene diisocyanate (m-, p-phenylene diisocyanate, or a mixture thereof), 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate, or a mixture thereof) (MDI), 4,4'-toluidine diisocyanate (TODI), and 4,4'-diphenyl ether diisocyanate. Component (A) may contain one of these aromatic polyisocyanates alone, or two or more of them may be used in combination.

Aromatic aliphatic polyisocyanates include, for example, bifunctional araliphatic diisocyanates such as xylylene diisocyanate (1,3- or 1,4-xylylene diisocyanate, or a mixture thereof) (XDI), tetramethyl xylylene diisocyanate (1,3- or 1,4-tetramethyl xylylene diisocyanate, or a mixture thereof) (TMXDI), ω,ω'-diisocyanato-1,4-diethylbenzene, etc. Component (A) may contain one of these araliphatic polyisocyanates alone, or two or more of them may be used in combination.

Aliphatic polyisocyanates include, for example, bifunctional aliphatic diisocyanates such as trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate), 1,5-pentamethylene diisocyanate (PDI), 1,6-hexamethylene diisocyanate (also known as hexamethylene diisocyanate) (HDI), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methylcaproate. Component (A) may contain one of these aliphatic polyisocyanates alone, or two or more of them may be used in combination.

Alicyclic polyisocyanates include, for example, 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, cyclohexane diisocyanate (1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as isophorone diisocyanate) (IPDI), hydrogenated xylylene diisocyanate (also known as bis(isocyanatomethyl)cyclohexane) (1,3- or 1,4-hydrogenated xylylene diisocyanate, or a mixture thereof) (H ₆ Examples of the difunctional alicyclic diisocyanates include hydrogenated diphenylmethane diisocyanate (also known as bis(isocyanatocyclohexyl)methane, methylene bis(cyclohexyl isocyanate)) (4,4'-, 2,4'-, or 2,2'-methylene bis(cyclohexyl isocyanate) in its trans-trans form, trans-cis form, cis-cis form, or mixtures thereof) (H ₁₂ MDI), methylcyclohexane diisocyanate (methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate), and norbornane diisocyanate (various isomers, or mixtures thereof) (NBDI). Component (A) may contain one of these alicyclic polyisocyanates alone, or two or more of them may be used in combination.

In one embodiment, component (A1) may contain one of the above polyisocyanate monomers alone or two or more of them in combination.

Polyisocyanate derivatives Examples of polyisocyanate derivatives include multimers of the above-mentioned polyisocyanate monomers (e.g., dimers, trimers (e.g., isocyanurate-modified products, iminooxadiazinedione-modified products), pentamers, heptamers, etc.), allophanate-modified products (e.g., allophanate-modified products produced by reacting the above-mentioned polyisocyanate monomers with known monohydric alcohols and/or known dihydric alcohols), polyol-modified products (e.g., polyol-modified products produced by reacting the above-mentioned polyisocyanate monomers with known trihydric or higher alcohols (alcohol adducts), etc.), biuret modified products (for example, a biuret modified product produced by the reaction of the polyisocyanate monomer with water or an amine), urea modified products (for example, a urea modified product produced by the reaction of the polyisocyanate monomer with a diamine), oxadiazinetrione modified products (for example, oxadiazinetrione produced by the reaction of the polyisocyanate monomer with carbon dioxide), carbodiimide modified products (for example, a carbodiimide modified product produced by a decarboxylation condensation reaction of the polyisocyanate monomer), uretdione modified products, uretonimine modified products, etc.

In one embodiment, component (A1) may contain one of the above-mentioned polyisocyanate derivatives alone, or two or more of them may be used in combination. From the viewpoint of easily adjusting the number of isocyanate groups (a) to more than 2, component (A1) preferably contains a polyisocyanate derivative. It may also contain a polymer of an aliphatic diisocyanate.

When the component (A) contains the component (A1), it is preferable to use a polyisocyanate having the above-mentioned isocyanate group concentration, number average molecular weight (Mn) and NCO equivalent.
In a more preferred embodiment, component (A) may contain component (A1) having an isocyanate group concentration of 20 to 30 mass% and an NCO equivalent of 100 to 200 g/mol. The proportion of component (A1) relative to the total mass of component (A) is preferably 10 to 100 mass%, more preferably 50 to 100 mass%.

Component (A) may further contain at least one (meth)acryloyl group. That is, component (A) may contain one or more components selected from component (A1) and (meth)acryloyl group-containing polyisocyanate (A2) containing at least two isocyanate groups and at least one (meth)acryloyl group. Note that the "(meth)acryloyl group" may contain both an acryloyl group and a methacryloyl group.

((Meth)acryloyl Group-Containing Polyisocyanate (A2))
The number of (meth)acryloyl groups in the (meth)acryloyl group-containing polyisocyanate (A2) (hereinafter sometimes referred to as "component (A2)") may be 1 to 10, 2 to 8, or 2 to 4. The number of isocyanate groups in component (A2) is 2 or more, and the upper limit is not particularly limited. In one embodiment, component (A2) may be an isocyanate group-containing urethane (meth)acrylate having at least one urethane bond, at least one (meth)acryloyl group, and at least two isocyanate groups in the molecule.

When component (A) contains component (A2), it is preferable to use a (meth)acryloyl group-containing polyisocyanate having the above-mentioned isocyanate group concentration, number average molecular weight (Mn), and NCO equivalent. In a more preferred embodiment, component (A) may contain component (A2) having an isocyanate group concentration of 10 to 15 mass% and an NCO equivalent of more than 200 and 350 or less g/mol. The ratio of component (A2) to the total mass of component (A) may be 0 to 90 mass%, or may be 0 to 50 mass%. In one embodiment, the ratio of component (A2) in component (A) may be 100 mass%.

Component (A2) may be a commercially available product, such as products manufactured by Daicel-Allnex Co., Ltd. under the product names "EBECRYL (registered trademark) 4141," "EBECRYL 4250," and "EBECRYL 4510." Component (A2) may be used alone or in combination of two or more types.

In one embodiment, from the viewpoint of easily achieving good thermosetting properties of the curable composition, it is preferable that component (A) contains component (A1).

From the viewpoint of making it easier to obtain an environmentally friendly curable composition, component (A1) and component (A2) may contain a component derived from biomass.

An example of the biomass-derived component (A1) (hereinafter, biomass-derived component (A1) will be referred to as "component (A11)") is polyisocyanate obtained from a plant-derived raw material. In one embodiment, component (A11) preferably has a biomass degree of 40% or more, more preferably 50% or more. An example of component (A11) having such a biomass degree is a dicarboxylic acid derived from a plant that has been converted into a terminal amino group by acid amidation and reduction, and then reacted with phosgene to convert the amino group into an isocyanate group. Preferably, an aliphatic polyisocyanate having 5 to 18 carbon atoms can be used, and specific examples include aliphatic diisocyanates obtained from plant-derived raw materials such as 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,7-heptamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate, dimer acid diisocyanate, octamethylene diisocyanate, and decamethylene diisocyanate. These may be used alone or in combination of two or more.

In one embodiment, component (A11) may be obtained by converting an amino group in an amino acid, which is a plant-derived raw material, to an isocyanate group. For example, the biomass-derived pentamethylene diisocyanate may be obtained by using lysine as a raw material.

In one embodiment, component (A11) may contain a derivative such as a polymer of an aliphatic polyisocyanate obtained from the above-mentioned plant-derived raw material, a biuret modified product, an allophanate modified product, an oxadiazinetrione modified product, or a polyol modified product. Of these, it is preferable to contain a polymer of an aliphatic polyisocyanate.

Examples of aliphatic polyisocyanate multimers obtained from plant-derived raw materials include dimers such as uretdione, uretoimine, and carbodiimide, and trimers and higher such as isocyanurate and iminooxadianedione, and it is more preferable to include isocyanurate. In a more preferred embodiment, component (A11) can include 1,5-pentamethylene diisocyanate and/or its derivatives (more preferably isocyanurate) obtained from plant-derived raw materials.

In another preferred embodiment, component (A11) may be an aliphatic polyisocyanate and/or its derivative obtained from the above-mentioned plant-derived raw material, having a biomass ratio of 50% or more and an isocyanate group concentration and NCO equivalent weight similar to those of the above-mentioned component (A1). As such component (A11), a commercially available product may be used, for example, products manufactured by Mitsui Chemicals, Inc. under the product names "STABIO (registered trademark) D-370N" and "STABIO D-376N", etc.

Component (A) can contain component (A11) in a ratio similar to that of component (A1) described above.

Component (A2) may also contain a biomass-derived component (A2) (hereinafter, biomass-derived component (A2) will be referred to as "component (A21)"). The biomass content of component (A21) may be any percentage.

Component (A) can contain component (A21) in a ratio similar to that of component (A2) described above.

(Polyol Component (B))
The curable component includes a polyol component (B) (hereinafter, sometimes referred to as "component (B)") having at least two hydroxyl groups. Here, "polyol component (B)" includes a polyol having at least two hydroxyl groups (e.g., polyol (B1) and/or (meth)acryloyl group-containing polyol (B2) described later) in an amount of 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, based on the total mass of component (B).

In one embodiment, the number of hydroxyl groups in component (B) (hereinafter referred to as "hydroxyl group number (b)") may be 2 or more and less than 4, from the viewpoint of more favorable balance between photocuring and thermal curing. When component (B) contains polyol (B1) and (meth)acryloyl group-containing polyol (B2) described later, the hydroxyl group number (b) is the total number of hydroxyl groups in polyols (B1) and (B2).

In one embodiment, the hydroxyl value of component (B) may be 10 to 2,000 KOHmg/g or 100 to 2,000 KOHmg/g. Also, the number average molecular weight (Mn) of component (B) may be 30 to 10,000, 50 to 5,000, or 90 to 1,600.
In one embodiment, the average hydroxyl equivalent of component (B) may be 30 to 5,000 g/mol, 30 to 1,000 g/mol, or 30 to 600 g/mol. If the number average molecular weight, hydroxyl value, and/or average hydroxyl equivalent of component (B) are within the above ranges, the curability is likely to be good. In this specification, the "hydroxyl value" can be a method according to the JIS standard. The number average molecular weight (Mn) of component (B) can be measured using GPC with a solvent of THF, a column temperature of 40°C, and a standard substance of standard polystyrene. In addition, the "average hydroxyl equivalent" (hereinafter sometimes referred to as "OH equivalent") may be a value measured according to the JIS standard, or a value calculated from the following formula (4).
(Molecular weight of KOH (56.1) × 100) / (Hydroxyl value (KOH mg / g)) × 100 ... (4)

Component (B) can contain a known or conventional polyol (B1) having at least two hydroxyl groups in the molecule.

(Polyol (B1))
The polyol (B1) (hereinafter, sometimes referred to as "component (B1)") is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polyoxy-C2-4 alkylene glycols (polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, etc.), polyester diols, polyether diols, polycarbonate diols, bisphenol A and its alkylene oxide adducts, bisphenol F and its alkylene oxide adducts, hydrogenated bisphenol A and its alkylene oxide adducts, and the like. Examples of the diols include alkylene oxide adducts, hydrogenated bisphenol F and its alkylene oxide adducts, cyclohexanediol, cyclohexanedimethanol, tricyclodecane dimethanol, isosorbide, and xylene glycol; and polyols having at least three hydroxyl groups in the molecule, such as glycerin, 1,1,1-tris(hydroxymethyl)propane, D-sorbitol, xylitol, D-mannitol, D-mannite, diglycerin, polyglycerin, trimethylolethane, trimethylolpropane, pentaerythritol, polyether polyol, polyester polyol, polycarbonate polyol, acrylic polyol, epoxy polyol, natural oil polyol, silicon polyol, fluorine polyol, and polyolefin polyol. Component (B1) may also be a polyoxyalkylene polyol obtained by adding an alkylene oxide to the above-mentioned polyol as an initiator. Component (B1) may be one of these alone or two or more of them in combination.

When the component (B) contains the component (B1), it is preferable to use a polyol having the above-mentioned hydroxyl value, number average molecular weight (Mn) and OH equivalent.
In a more preferred embodiment, component (B) may contain component (B1) having a hydroxyl value of 10 to 2,000 KOHmg/g and an OH equivalent of 30 to 5,000 g/mol. The proportion of component (B1) relative to the total mass of component (B) is preferably 10 to 100 mass%, more preferably 20 to 100 mass%, and even more preferably 50 to 100 mass%.

Component (B) may further contain at least one (meth)acryloyl group. That is, component (B) may contain one or more components selected from component (B1) and (meth)acryloyl group-containing polyol (B2) containing at least two hydroxyl groups and at least one (meth)acryloyl group.

((Meth)acryloyl Group-Containing Polyol (B2))
The number of (meth)acryloyl groups in the (meth)acryloyl group-containing polyol (hereinafter sometimes referred to as "component (B2)") may be 1 to 10, 2 to 8, or 2 to 4. The number of hydroxyl groups in component (B2) may be 2 to 10, 2 to 8, or 2 to 4. In one embodiment, component (B2) may be a hydroxyl group-containing urethane (meth)acrylate having at least one urethane bond, at least one (meth)acryloyl group, and at least two hydroxyl groups in the molecule.

Examples of component (B2) include trimethylolpropane (meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol (meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, ditrimethylolpropane (meth)acrylate, ditrimethylolpropane di(meth)acrylate, etc. These may be used alone or in combination of two or more.

When the component (B) contains the component (B2), it is preferable to use a (meth)acryloyl group-containing polyol having the above-mentioned hydroxyl value, number average molecular weight (Mn) and OH equivalent.
In a more preferred embodiment, component (B) may contain one or more components (B2) having a hydroxyl value of 150 to 350 KOHmg/g and an OH equivalent of 100 to 600 g/mol. The proportion of component (B2) relative to the total mass of component (B) may be any value within the range of 10 to 100 mass%.

In one embodiment, from the viewpoint of making it easier to balance photocuring and thermal curing, it is preferable that component (B) contains component (B2).

From the viewpoint of making it easier to obtain an environmentally friendly curable composition, component (B1) and component (B2) may contain a component derived from biomass.

Biomass-derived component (B1) (hereinafter biomass-derived component (B1) will be referred to as "component (B11)") is, for example, a polyol compound obtained from a plant-derived raw material, preferably having a biomass degree of 20% or more, more preferably 40% or more, and even more preferably 50% or more. The biomass degree of component (B11) may be 100%. Examples of such polyol compounds include isosorbide, vegetable oil-based polyols, vegetable raw material glycerin, bioethylene glycol, bio-1,3-propane glycol, and biobutylene glycol. These may be used alone or in combination of two or more.

Examples of vegetable oil-based polyols include castor oil-based polyols, soybean oil-based polyols, palm oil-based polyols, palm kernel oil-based polyols, coconut oil-based polyols, cashew oil-based polyols, olive oil-based polyols, cottonseed oil-based polyols, safflower oil-based polyols, sesame oil-based polyols, sunflower oil-based polyols, linseed oil-based polyols, etc. Polyols derived from vegetable oils usually have 2 to 3 hydroxyl groups per molecule.
Examples of castor oil-based polyols include castor oil, a reaction product of castor oil with a polyol, an esterification reaction product of castor oil fatty acid with a polyol, etc. Examples of polyols to be reacted with castor oil or castor oil fatty acid include divalent polyols such as ethylene glycol, diethylene glycol, and propylene glycol, and trivalent or higher polyols such as glycerin, trimethylolpropane, hexanetriol, and sorbitol.
The soybean oil-based polyol may be a polyol derived from soybean oil, such as a reaction product of soybean oil and a polyol, or an esterification reaction product of soybean oil fatty acid and a polyol. The polyol to be reacted with soybean oil or soybean oil fatty acid may be the same as that of castor oil. The same applies to palm oil-based polyol, cashew oil-based polyol, etc.

Component (B) can contain component (B11) in a proportion similar to that of component (B1) described above.

In one embodiment, the aforementioned component (B2) may also include a biomass-derived component (B2) (hereinafter, the biomass-derived component (B2) will be referred to as "component (B21)").

As component (B21), a biomass degree of 10% or more is preferred, 20% or more is more preferred, and 30% or more is even more preferred. In one embodiment, from the viewpoint of obtaining a curable composition with a better balance between photocuring and thermal curing, a polyol-modified (meth)acrylate having 2 to 4 hydroxyl groups and 1 to 4 (meth)acryloyl groups is preferred. As such polyol-modified (meth)acrylate, sorbitol-modified (meth)acrylate (hydroxyl group number: 4, (meth)acryloyl group number: 2) and epoxidized soybean oil-modified (meth)acrylate (hydroxyl group number: 3.5, (meth)acryloyl group number: 3.5) are particularly preferred. Such polyol-modified (meth)acrylates may be commercially available products, such as "Aronix (registered trademark) M-926" manufactured by Toagosei Co., Ltd. and "EBECRYL 5848" manufactured by Daicel Allnex Co., Ltd. As mentioned above, component (B) also includes compounds that generate hydroxyl groups in the molecule by ring-opening.

((Meth)acrylate Component (C))
The curable component contained in the curable composition according to the present embodiment may contain a (meth)acrylate component (C) (hereinafter, sometimes referred to as "component (C)") containing at least one (meth)acryloyl group. Here, the "(meth)acrylate component (C)" contains 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more of a (meth)acrylate having at least one (meth)acryloyl group (e.g., a monofunctional or more (meth)acrylate (C1) and/or a hydroxyl group-containing (meth)acrylate (C2) described later) relative to the total mass of component (C).

The curable composition according to the present embodiment contains a curable component that contains an isocyanate group, a hydroxyl group, and a (meth)acryloyl group. Of these, the (meth)acryloyl group may be contained in one or more components selected from component (A) and component (B), or may be separately blended as component (C), or may be both. In this way, by containing three different functional groups, the curable composition according to the present embodiment can be made into a dual cure material that can be used in combination with photocuring and heat curing. Furthermore, by arbitrarily adjusting the number of isocyanate groups, hydroxyl groups, and (meth)acryloyl groups in the curable component, the composition after photocuring can be heat cured at a lower temperature than before.

In one embodiment, the number of (meth)acryloyl groups in component (C) (hereinafter referred to as "(meth)acryloyl number (c)") may be 1 to 20, 1 to 10, or 1 to 6. If the (meth)acryloyl group number (c) is within the above range, it becomes easier to balance photocuring and thermal curing, and the amount of energy used during production tends to be reduced. Note that when component (C) contains a monofunctional or higher (meth)acrylate (C1) and a hydroxyl group-containing (meth)acrylate (C2) described below, the (meth)acryloyl number (c) is the sum of the (meth)acryloyl numbers of (meth)acrylates (C1) and (C2).

Component (C) can contain a monofunctional or higher (meth)acrylate (C1) (hereinafter sometimes referred to as "component (C1)") that contains at least one (meth)acryloyl group in the molecule.

(Monofunctional or higher (meth)acrylate (C1))
Examples of the monofunctional (meth)acrylate in component (C1) include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, butoxyethyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and lauryl. Examples of the acrylates include aliphatic (meth)acrylates such as (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; and alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more.

Examples of bifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, and poly Propylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, Aliphatic (meth)acrylates such as 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, and ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate; cyclohexane dimethanol (meth)acrylate, ethoxylated cyclohexane dimethanol (meth)acrylate, propoxylated cyclohexane dimethanol (meth)acrylate, and ethoxylated propoxylated cyclohexane dimethanol (meth)acrylate , tricyclodecane dimethanol (meth)acrylate, ethoxylated tricyclodecane dimethanol (meth)acrylate, propoxylated tricyclodecane dimethanol (meth)acrylate, ethoxylated propoxylated tricyclodecane dimethanol (meth)acrylate, ethoxylated hydrogenated bisphenol A di(meth)acrylate, propoxylated hydrogenated bisphenol A di(meth)acrylate, ethoxylated propoxylated hydrogenated bisphenol A di(meth)acrylate, and other alicyclic (meth)acrylates. These may be used alone or in combination of two or more.

Examples of the trifunctional or higher (meth)acrylate include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, propoxylated ... propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, propoxylated pentaeryth Examples of the aliphatic (meth)acrylates include aliphatic (meth)acrylates such as ethoxylated propoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. These may be used alone or in combination of two or more.
Of these, from the viewpoint of the strength of the coating film, it is preferable that the composition contains a di- or higher functional (meth)acrylate, and it may contain a trifunctional (meth)acrylate or a tetrafunctional (meth)acrylate.

(Hydroxyl Group-Containing (Meth)Acrylate (C2))
In one embodiment, component (C) may contain a hydroxyl group-containing (meth)acrylate (C2) (hereinafter, sometimes referred to as "component (C2)") that contains at least one (meth)acryloyl group and a hydroxyl group. Here, the number of hydroxyl groups contained in component (C2) is more than 0 and less than 2. The (meth)acrylate having 2 or more hydroxyl groups is contained in the above-mentioned component (B2).

In one embodiment, the number of (meth)acryloyl groups in component (C2) is not particularly limited and may be 1 to 20, 1 to 10, or 1 to 6.

Examples of component (C2) containing one each of a (meth)acryloyl group and a hydroxyl group in the molecule include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and hydroxy(meth)acrylate compounds such as (poly)alkylene glycol mono(meth)acrylates such as (poly)ethylene glycol mono(meth)acrylate and (poly)propyne glycol mono(meth)acrylate. These may be used alone or in combination of two or more.

Examples of component (C2) containing two or more (meth)acryloyl groups and more than 0 and less than 1 hydroxyl group include glycerin-modified (meth)acrylate (number of hydroxyl groups: 0.5, number of (meth)acryloyl groups: 2.5), pentaerythritol triacrylate, etc. These may be used alone or in combination of two or more.

In one embodiment, from the viewpoint of achieving good thermosetting properties, it is preferable that component (C) contains component (C2). It is more preferable that component (C) contains a hydroxyl group-containing (meth)acrylate that contains two or more (meth)acryloyl groups and more than 0 but less than 1 hydroxyl group.

From the viewpoint of making it easier to obtain an environmentally friendly curable composition, component (C2) may contain a biomass-derived component (hereinafter, biomass-derived component (C2) will be referred to as "component (C21)". Component (C21) may contain the above-mentioned component (B11) as a raw material. Furthermore, the biomass degree of component (C21) is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. As such component (C21), a commercially available product may be used, for example, "Aronix M-920" (a plant-derived raw material glycerin-modified (meth)acrylate) manufactured by Toagosei Co., Ltd.

(Other ingredients)
In one embodiment, the curable component may contain a component (other component) other than the above-mentioned components (A) to (C). Examples of the other component include an isocyanate component other than component (A) and a hydroxyl group component other than component (B).

Examples of isocyanate components other than component (A) include isocyanate monomers and/or isocyanate derivatives having more than 0 and less than 2 isocyanate groups in the molecule; (meth)acryloyl group-containing isocyanates other than component (A2) (having more than 0 and less than 2 isocyanate groups in the molecule). These may be used alone or in combination of two or more.

Examples of hydroxyl group components other than component (B) include monools such as methanol and ethanol. These may be used alone or in combination of two or more.

In one embodiment, the isocyanate index (average isocyanate group equivalent/average hydroxyl group equivalent) of the curable component is preferably 0.01 to 2.0, more preferably 0.1 to 1.5, and even more preferably 0.2 to 1.2. In a particularly preferred embodiment, the isocyanate index may be 1.0. By setting the isocyanate index within the above range, a curable composition with a better balance between photocuring and thermal curing is likely to be obtained. The isocyanate index refers to a value calculated based on the total isocyanate groups and total hydroxyl groups contained in the curable component. When the curable component contains an isocyanate component other than the above-mentioned component (A) and a hydroxyl group-containing component other than the component (B) and the component (C2), it is preferable to contain these components within a range that satisfies the above-mentioned isocyanate index.

In one embodiment, the ratio of the biomass-derived components to the total mass of the curable components is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. From the viewpoint of making a curable composition more environmentally friendly, the ratio of the biomass components to the total mass of the curable components may be 100%.

<Photopolymerization initiator>
The curable composition according to the first embodiment further contains a photopolymerization initiator.
Examples of the photopolymerization initiator include benzophenone, acetophenone benzyl, benzyl dimethyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, dimethoxyacetophenone, dimethoxyphenylacetophenone, diethoxyacetophenone, diphenyl disulfite, methyl orthobenzoylbenzoate, ethyl 4-dimethylaminobenzoate (e.g., Nippon Kayaku Co., Ltd., trade name "KAYACURE (registered trademark) EPA" and the like), 2,4-diethylthioxanthone (e.g., Nippon Kayaku Co., Ltd., trade name "KAYACURE DETX" and the like), 2-methyl-1-[4-(methyl)phenyl]-2-morpholinopropanone-1 (e.g., Ciba-Geigy Co., Ltd., trade name "Irgacure (registered trademark) 907), 1-hydroxycyclohexyl phenyl ketone (for example, trade name "Omn184" manufactured by IGM, etc.), 2-amino-2-benzoyl-1-phenylalkane compounds such as 2-dimethylamino-2-(4-morpholino)benzoyl-1-phenylpropane, aminobenzene derivatives such as tetra(t-butylperoxycarbonyl)benzophenone, benzil, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and 4,4'-bis(diethylamino)benzophenone, 2,2'- Examples of the compound include imidazole compounds such as bis(2-chlorophenyl)-4,5,4',5'-tetraphenyl-1,2'-biimidazole (for example, trade name "B-CIM" manufactured by Hodogaya Chemical Co., Ltd.), halomethylated triazine compounds such as 2,6-bis(trichloromethyl)-4-(4-methoxynaphthalen-1-yl)-1,3,5-triazine, and halomethyloxadiazole compounds such as 2-trichloromethyl-5-(2-benzofuran-2-yl-ethenyl)-1,3,4-oxadiazole. These compounds may be used alone or in combination of two or more. If necessary, a photosensitizer may be added.

The content of the photopolymerization initiator in the curable composition is preferably 0.5 to 12% by mass, more preferably 0.5 to 10% by mass, and even more preferably 0.5 to 8% by mass, based on the total mass of the curable composition. When the content of the photopolymerization initiator is within the above range, the curable composition according to this embodiment can be appropriately cured by ultraviolet light, which will be described later.

(Other additives)
The curable composition according to the present embodiment may contain any component (other additives) other than the curable component and the photopolymerization initiator. The other additives are not particularly limited, and any additive that can be blended in the photocurable composition and/or the thermosetting composition may be blended. For example, a radical polymerization initiator other than the photopolymerization initiator, an ultraviolet absorber, a reaction accelerator, a light stabilizer, a surface conditioner, etc. may be blended.

Ultraviolet Absorber Any known or commonly used ultraviolet absorber can be used, and is not particularly limited. Examples of the ultraviolet absorber include cyanoacrylate-based, dihydroxybenzophenone-based, benzotriazole-based, triazine-based, and benzophenone-based ultraviolet absorbers.

Examples of cyanoacrylate ultraviolet absorbers include 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, and ethyl-2-cyano-3,3-diphenylacrylate.
Examples of dihydroxybenzophenone-based ultraviolet absorbers include 2-hydroxy-4-methoxybenzophenone, (2,4-dihydroxyphenyl)-phenylmethanone, hydroxymethoxybenzophenonesulfonic acid, 2-(2H-benzotriazol-2-yl)-4-methyl, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl), and 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methyl.
Examples of benzotriazole-based ultraviolet absorbers include 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(5-chloro-2H-benzotriazol-2-yl)-6-tertiarybutyl-4-methylphenol, and 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol].
Examples of triazine-based ultraviolet absorbers include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoloxy)ethoxy]phenol, 2-(4-((2-hydroxy-3-dodecyloxypropyl)oxy)-2-hydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and 2-(4-((2-hydroxy-3-tridecyloxypropyl)oxy)-2-hydroxyphenyl)-4,6-bis (2,4-dimethylphenyl)-1,3,5-triazine, 2-(4-((2-hydroxy-3-(2'ethyl)hexyl)oxy)-2-hydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bisbutyloxyphenyl)-1,3,5-triazine, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxy, and the like.
An example of the benzophenone-based ultraviolet absorber is [2-hydroxy-4-(octyloxy)phenyl]phenylmethanone. The ultraviolet absorbers may be used alone or in combination of two or more.

Light stabilizer As the light stabilizer, known or conventional ones can be used, and there is no particular limitation. Examples of the light stabilizer include 2,2,6,6-tetraalkyl-4-piperidyl esters (2,2,6,6-tetramethyl-4-piperidyl esters, etc.), 4-alkoxy-2,2,6,6-tetraalkylpiperidines (for example, 4-(C1-10 alkoxy)-2,2,6,6-piperidines such as 4-methoxy-2,2,6,6-tetramethylpiperidine; 4-(C6-10 aryloxy)-2,2,6,6-piperidines such as 4-phenoxy-2,2,6,6-tetramethylpiperidine; 4-(C6-10 aryl)-(C1-4 alkyl)-2,2,6,6-tetramethylpiperidines such as 4-benzyloxy-2,2,6,6-tetramethylpiperidine, etc.), biphenyls, bis(2,2,6,6-tetraalkyl-4-piperidyloxy)alkanes [for example, bis(2,2,6,6-tetramethyl-4-piperidyloxy)(C2-6 alkanes) such as 1,2-bis(2,2,6,6-tetramethyl-4-piperidyloxy)ethane], tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate; bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate; reaction products of 1,2,3,4-butanetetracarboxylic acid tetramethyl ester with 1,2,2,6,6-pentamethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, and the like. The light stabilizers may be used alone or in combination of two or more.

Reaction accelerators that can be used include known or conventional reaction accelerators, and are not particularly limited. Examples of reaction accelerators include 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) or a salt thereof (e.g., phenol salt, octylate salt, p-toluenesulfonate, formate salt, tetraphenylborate salt, etc.); 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) or a salt thereof (e.g., phenol salt, octylate salt, p-toluenesulfonate, formate salt, tetraphenylborate salt, etc.); benzyldimethylamine, 2,4,6-tris(dimethylamine), Examples of the reaction accelerator include tertiary amines such as 2-ethyl-4-methylimidazole and 1-cyanoethyl-2-ethyl-4-methylimidazole, phosphoric acid esters, phosphines such as triphenylphosphine and tris(dimethoxy)phosphine, phosphonium compounds such as tetraphenylphosphonium tetra(p-tolyl)borate, organic metal salts such as zinc octoate, tin octoate and zinc stearate, and metal chelates such as aluminum acetylacetone complex. Note that one type of reaction accelerator may be used alone, or two or more types may be used in combination.

<Method of producing curable composition>
The curable composition according to the first embodiment can be produced by mixing the above-mentioned curable component, the photopolymerization initiator, and, if necessary, the above-mentioned other additives. As a means for mixing, a known or conventional means, for example, various mixers such as a dissolver or a homogenizer, a kneader, a roll, a bead mill, a self-rotating stirring device, etc., can be used. Conditions such as temperature and rotation speed during mixing are not particularly limited and can be appropriately set.

The curable composition according to the first embodiment can be cured with less thermal energy than conventional methods by combining photocuring and thermal curing. Such a curable composition can be suitably used, for example, as an impregnating resin, an adhesive layer composition, and a topcoat layer composition for decorative boards and decorative papers. Needless to say, the uses of the curable composition are not limited to these decorative boards and decorative papers.

[Cured product]
The second embodiment of the present disclosure is a cured product of the curable composition according to the first embodiment. The curable composition according to the first embodiment can be made into a cured product by a combination of light irradiation and heating. The cured product according to the second embodiment includes both the above-mentioned curable composition irradiated with ultraviolet rays or active energy rays to be described later to promote the curing reaction, and the cured product completely cured by thermal curing after photocuring. In addition, the cured product of this embodiment also includes a "semi-cured product" in which the curable composition is irradiated with light or heated and cured to the extent that it loses fluidity.

The cured product according to this embodiment can be obtained as a cured coating film by, for example, applying the curable composition according to the first embodiment to an object such as a substrate, followed by photocuring and/or thermal curing.

The method for applying the curable composition is not particularly limited, and any conventionally known method can be used, such as a coating method or a casting method.

(light curing)
The photocuring is preferably carried out by irradiation with active energy rays such as ultraviolet rays or electron beams.
Examples of light sources that can be used for ultraviolet irradiation include high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, etc. The ultraviolet irradiation time can be adjusted as desired between several seconds and several tens of seconds depending on the type of light source, the distance between the light source and the coated surface, and other conditions.
On the other hand, in the case of electron beam irradiation, it is preferable to use an electron beam having an energy in the range of, for example, 50 to 1000 KeV, and to set the irradiation dose at 2 to 5 Mrad. Usually, an irradiation source with a lamp output of about 80 to 300 W/cm is used.

(thermal curing)
The photocuring is preferably followed by further heat curing. The temperature during heat curing is not particularly limited as long as it is a temperature at which the curable composition can be cured, but from the viewpoint of reducing thermal energy during production, room temperature is preferred, and from the viewpoint of working speed, heating is preferred.

The thickness of the cured coating film is not particularly limited and can be adjusted as desired depending on the application. For example, it may be adjusted to a range of 0.5 to 1,000 μm, preferably 2 to 500 μm.

The object (subject to be coated) onto which the curable composition is applied is not particularly limited, but examples include plastic articles such as polyethylene terephthalate (PET), polycarbonate, polymethacrylate, polyvinyl chloride resin, etc., the above-mentioned articles whose plastic surfaces have been subjected to metal deposition, glass, wood, metal plates, paper, and various other articles. The coated surface may be subjected to a release treatment.

[Laminate]
The third embodiment of the present disclosure is a laminate comprising a layer containing one or more layers selected from the curable composition according to the first embodiment and the cured product according to the second embodiment. Such a laminate is not particularly limited, but is preferably a decorative paper or a decorative board. Hereinafter, the details of the decorative paper and the decorative board will be described as one aspect of the laminate.

<Decorative paper>
When the laminate according to the third embodiment is a decorative paper, the decorative paper is obtained by impregnating a porous base paper with the curable composition according to the first embodiment and then curing the same. The surface of the decorative paper may be provided with a patterned layer for enhancing design, a topcoat layer for enhancing smoothness, or the like. That is, the decorative paper according to this embodiment may be a multilayer body having a layer containing the curable composition and/or the cured product according to this embodiment.

The porous base paper may be any fibrous sheet-like material such as paper with good water absorption that can be impregnated with the curable composition, and examples of such materials that can be used include tissue paper, titanium paper, fine paper, bleached or unbleached kraft paper, etc. Among these, it is preferable to use titanium paper, which has excellent suitability for both printing and resin impregnation.

<Decorative board>
The decorative paper obtained above can be further attached to a substrate to obtain a decorative board.

1 is a cross-sectional view showing an example of a decorative board 100 including a decorative paper 10 containing the curable composition and/or cured product according to this embodiment as an impregnated resin, and a substrate 20. The decorative paper 10 in the decorative board 100 in FIG. 1 includes a porous base paper 1, a topcoat layer 2, and an adhesive layer 3. The porous base paper 1 is impregnated with the curable composition and/or cured product according to this embodiment. In addition, in the decorative paper 10 in FIG. 1, the topcoat layer 2 and the adhesive layer 3 are also composed of the curable composition and/or cured product according to this embodiment. In such a decorative board 100, for example, the curable composition according to this embodiment is applied to one surface of the substrate 20 by any method, and then the porous base paper 1 is laminated to impregnate the porous base paper 1 with the curable composition. As a result, the adhesive layer 3 can also be laminated on one surface of the porous base paper 1 (the surface on the substrate 20 side). After that, the curable composition according to this embodiment is further applied to the other surface of the porous base paper 1, and the topcoat layer 2 is laminated. After the surface of the topcoat layer 2 is covered with a resin film (such as a PET film), ultraviolet light or active energy rays are irradiated from the resin film side to harden the topcoat layer 2. The resin film is then peeled off and further thermally hardened to harden the impregnated resin and adhesive layer 3. This allows the decorative paper 10 and the substrate 20 to be integrated together to obtain the decorative board 100.

The substrate 20 is preferably a plate-shaped substrate, and for example, an inorganic substrate, a wood substrate, an organic substrate, or the like can be used.
Examples of inorganic substrates include cement boards, volcanic glass laminate boards, calcium silicate boards, magnesium silicate boards, and magnesium oxide boards.
Examples of wood substrates include plywood, insulation board, MDF (medium density fiberboard), hardboard, particle board, and oriented strand board.
Examples of organic substrates include plastic plates of thermosetting resins or thermoplastic resins, and specific examples thereof include phenolic resin plates, polycarbonate plates, acrylic resin plates, hard polyvinyl chloride plates, soft polyvinyl chloride plates, polypropylene resin plates, polystyrene resin plates, polyethylene terephthalate (PET) resin plates, etc. Among these, inorganic substrates are preferred from the viewpoints of easily obtaining decorative boards with excellent non-flammability and excellent strength.

The thickness of the substrate 20 is not particularly limited, but from the standpoint of the strength of the substrate and ease of handling, a thickness of 20 μm to 25 mm is preferable.

As described above, the decorative paper and decorative board containing the curable composition according to this embodiment can be produced with less thermal energy than conventional methods because the impregnated resin can be cured by a combination of photocuring and heat curing.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[material]
The materials used in the examples and comparative examples are as follows. The details of each component are shown in Table 1.
<Component (A)>
Component (A11-1): Biomass-derived 1,5-pentamethylene diisocyanate derivative (manufactured by Mitsui Chemicals, Inc., product name "STABIO D-370N").
Component (A11-2): Biomass-derived 1,5-pentamethylene diisocyanate derivative (manufactured by Mitsui Chemicals, Inc., product name "STABIO D-376N").
Component (A2-1): Isocyanate group-containing acrylate (manufactured by Daicel Allnex Corporation, product name "EBECRYL 4141").
<Component (B)>
Ingredient (B11-1): Glycerin derived from plant material (manufactured by Sakamoto Pharmaceutical Industry Co., Ltd., product name "R-PG").
Component (B21-1): Sorbitol-modified acrylate (manufactured by Toagosei Co., Ltd., product name "Aronix M-926").
Component (B21-2): soybean oil modified epoxy acrylate (manufactured by Daicel Allnex Co., Ltd., product name "EBECRYL 5848").
<Component (C)>
Component (C21-1): Glycerin modified acrylate (manufactured by Toa Gosei Co., Ltd., product name "Aronix M-920").
<Photopolymerization initiator>
1-Hydroxycyclohexyl phenyl ketone (manufactured by IGM, trade name "Omn184").
<Reaction accelerator>
1,8-diazabicyclo[5.4.0]undecene-7 (DBU).

[Examples 1 to 3 and Comparative Examples 1 to 4]
Using the above materials, a curable composition was obtained by mixing each component in the composition and content ratio shown in Table 2. The obtained curable composition was evaluated for curability and adhesion under the following conditions. The results are shown in Table 2.

<Curability and Adhesion Evaluation>
The curable composition was applied to the surface of the base PET film (thickness 100 μm) at 100 g/m ^2. Then, a porous base paper (impregnated titanium base paper, manufactured by KJ Specialty Paper Co., Ltd.) was laminated, and the porous base paper was impregnated with the curable composition to obtain a paper layer. The curable composition was further applied to the paper layer at 100 g/m ² , and the outermost surface was covered with a protective PET film (thickness 100 μm) to obtain a laminate in the order of base PET film/adhesive layer (curable composition)/paper layer/topcoat layer (curable composition)/protective PET film.
(Photocuring evaluation)
The obtained laminate was photocured by irradiating ultraviolet light from the protective PET film side (light source: high pressure mercury lamp, irradiation conditions: 2 kW, 4 m, 2 passes, cumulative light amount: 800 mJ/ ^cm2 ). The protective PET film was then peeled off, and the curability of the topcoat layer was evaluated according to the following evaluation criterion 1. In addition, the paper layer was peeled off, and the curability of the paper layer and the curability of the adhesive layer were evaluated according to evaluation criterion 2.
(Evaluation Criteria 1)
A: The top coat layer has no tack when touched with a finger.
B: The top coat layer is tacky when touched with a finger.
(Evaluation Criteria 2)
A: The base PET film and the paper layer were adhered to each other (the paper layer and the adhesive layer were cured).
B: The base PET film and the paper layer were not adhered to each other (the paper layer and adhesive layer were not cured).
(Photocuring and heat curing evaluation)
The obtained laminate was photocured under the same conditions as above, and then placed in an oven at 80° C. to measure the time until all layers were cured. After completion of thermal curing, the protective PET film was peeled off, and the curability of the topcoat layer was evaluated according to the above-mentioned Evaluation Criteria 1. In addition, the paper layer was peeled off, and the curability of the paper layer and the curability of the adhesive layer were evaluated according to the above-mentioned Evaluation Criteria 2. Furthermore, the curability in photocuring and thermal curing was evaluated according to the following Evaluation Criteria 3.
(Evaluation Criteria 3)
Pass: The topcoat layer, the paper layer, and the adhesive layer were all cured, and the time required for heat curing was less than 30 minutes.
Fail: Either the topcoat layer, the paper layer, or the adhesive layer was not cured, or all layers were cured but the time required for heat curing was more than 30 minutes.
(Adhesion Evaluation)
After the above photocuring and heat curing, the peelability when peeling the paper layer from the base PET film was evaluated on a 5-point scale, with "0" being uncured and "5" being the most closely attached (difficult to peel), and the peelability between the paper layer and the base PET film was evaluated on a scale of 0, 1, 2, 3, 4, and 5, with 4 or more being considered a pass.

As shown in Table 2, in Examples 1 to 4, which satisfy the configuration of the curable composition according to the first embodiment, the topcoat layer, the paper layer, and the adhesive layer were all cured by photocuring and heat curing. Furthermore, the time required for heat curing was less than 30 minutes. On the other hand, in the curable compositions of Comparative Examples 1 to 3, which do not contain component (B), the topcoat layer was cured by photocuring, but the paper layer and the adhesive layer were not cured even when heated for 60 minutes or more. In addition, in the curable composition of Comparative Example 4, which does not contain a (meth)acryloyl group, the paper layer and the adhesive layer were cured by photocuring and heat curing, but the topcoat layer was not cured. In order to completely cure the curable composition of Comparative Example 4, it is considered that it is necessary to perform heat curing by heat pressing or at a higher temperature condition.
From the above results, it was found that the curable composition according to the first embodiment can be cured with less thermal energy than conventional curable compositions. Furthermore, as shown in Examples 1 to 4, by using a biomass-derived material, it is possible to obtain an environmentally friendly curable composition with fewer petroleum-derived components. Such a curable composition and/or cured product can be suitably used as an impregnating resin for decorative paper and decorative boards. It can also be suitably used as a curable composition for an adhesive layer or a topcoat layer.

1: Porous base paper 2: Topcoat layer 3: Adhesive layer 10: Decorative paper 20: Substrate 100: Decorative board

Claims (8)

Contains a curable component and a photopolymerization initiator,
The curable component is
A (meth)acryloyl group-containing polyisocyanate component (A2) containing at least two isocyanate groups and at least one (meth)acryloyl group;
A curable composition comprising one or more selected from a polyol component (B1) containing at least two hydroxyl groups, and a (meth)acryloyl group-containing polyol component (B2) containing at least two hydroxyl groups and at least one (meth)acryloyl group. The curable composition according to claim 1 , wherein a ratio of the biomass-derived component to a total mass of the curable component is 10 mass% or more. The curable composition of claim 1 or 2 , wherein the curable component further comprises a (meth)acrylate component (C) containing at least one (meth)acryloyl group. The curable composition according to claim 1 or 2 , wherein the average hydroxyl equivalent of the component (B1) is 30 to 5,000. The curable composition according to claim 1 or 2 , wherein the curable component has an isocyanate index (average isocyanate group equivalent/average hydroxyl group equivalent) of 0.01 to 2.0. A cured product of the curable composition according to claim 1. A laminate comprising at least one layer selected from the curable composition according to claim 1 and the cured product according to claim 6 . The laminate according to claim 7 , which is a resin-impregnated decorative paper or a resin-impregnated decorative board.

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