Urethane (METH)acrylate compound, active energy ray-curable resin composition, coating agent, and sheet

Abstract

To provide a urethane (meth)acrylate compound that enables formation of a cured coating film with an excellent balance between elongation and surface tackiness, as well as an active energy ray-curable resin composition, a coating agent, and a sheet comprising the urethane (meth)acrylate compound.SOLUTION: A urethane (meth)acrylate compound comprises: a structural unit originating from a polyisocyanate compound (a1); a structural unit originating from a polyol compound (a2-1) whose average functionality exceeds 2.0, and a structural unit originating from a hydroxyl group-containing (meth)acrylate compound (a3), with the polyol compound (a2-1) having a melting point of 15°C or more and a number-average molecular weight of 500 or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a urethane (meth)acrylate compound, an active energy ray-curable resin composition, a coating agent, and a sheet. [Background technology]

[0002] Conventionally, active energy ray-curable resin compositions are cured completely by irradiation with energy rays for a very short time, and therefore have been widely used in applications such as coating agents for various substrates, adhesives, pressure sensitive adhesives, inks, etc. Urethane (meth)acrylate compounds are well known as components constituting such active energy ray-curable resin compositions.

[0003] As a composition containing a urethane (meth)acrylate compound, for example, Patent Document 1 discloses a composition containing a prepolymer obtained by reacting a polyether polyol, a polycarbonate polyol, a polyisocyanate, and a hydroxyl group-containing (meth)acrylate. Patent Document 2 discloses a composition containing specific amounts of phenoxyethyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, and a difunctional urethane (meth)acrylate. Patent Document 3 discloses a composition containing a urethane (meth)acrylate having a specific structural unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-180328 A [Patent Document 2] JP 2013-43894 A [Patent Document 3] JP 2017-48301 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the cured coating film formed using the composition described in Patent Document 1 has excellent tensile strength and tensile elongation, it tends to leave a sticky feeling on the coating film surface. A cured coating film formed using the composition described in Patent Document 2 has good adhesion to the substrate, but has a strong tackiness and is difficult to handle. Although the cured coating film formed using the composition described in Patent Document 3 has excellent elastic modulus and elongation, the stickiness of the coating film surface has not been investigated. It is generally believed that there is a trade-off between the elongation and surface tackiness of a cured coating film.

[0006] The present invention aims to provide a urethane (meth)acrylate compound capable of forming a cured coating film having an excellent balance between elongation and surface tackiness, and an active energy ray-curable resin composition, a coating agent, and a sheet each using the urethane (meth)acrylate compound. [Means for solving the problem]

[0007] The present invention includes the following aspects. [1] A copolymer having a structural unit derived from a polyisocyanate compound (a1), a structural unit derived from a polyol compound (a2-1), and a structural unit derived from a hydroxyl group-containing (meth)acrylate compound (a3), The polyol compound (a2-1) has a melting point of 15° C. or higher and a number average molecular weight of 500 or higher. [2] The urethane (meth)acrylate compound according to [1], wherein the polyisocyanate compound (a1) is an alicyclic diisocyanate. [3] The urethane (meth)acrylate compound according to [1] or [2], further comprising a structural unit derived from a polyol compound (a2-2) having a molecular weight of 300 or less (excluding the polyol compound (a2-1)). [4] The elongation of a cured coating film having a thickness of 100 μm formed using the urethane (meth)acrylate compound is 200% or more at 23° C. in a tensile test; the tack value of the cured coating film at 23°C in a probe tack test is 1.0 or less; The urethane (meth)acrylate compound according to any one of the above [1] to [3], wherein the cured coating film has a glass transition temperature of 0° C. or lower. [5] The urethane (meth)acrylate compound according to any one of the above [1] to [4], wherein the urethane (meth)acrylate compound has a weight average molecular weight of 10,000 to 100,000. [6] An active energy ray-curable resin composition comprising the urethane (meth)acrylate compound according to any one of [1] to [5] above. [7] A coating agent comprising the active energy ray-curable resin composition according to [6]. [8] A sheet comprising a cured product of the active energy ray-curable resin composition described in [6]. Effect of the Invention

[0008] According to the present invention, it is possible to provide a urethane (meth)acrylate compound capable of forming a cured coating film having an excellent balance between elongation and surface tackiness, and an active energy ray-curable resin composition, a coating agent, and a sheet each using the urethane (meth)acrylate compound. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in further detail below by presenting preferred embodiments of the invention. However, the following description is one example of an embodiment of the present invention, and the present invention is not limited to the contents described below as long as it does not go beyond the gist of the invention. In the present invention, "(meth)acrylate" is a general term for "acrylate" and "methacrylate", and the same applies to "(meth)acryl" and "(meth)acryloyl". In the present invention, a numerical range expressed by "to" means a numerical range including the numerical values ​​before and after "to" as the lower and upper limits. For example, A to B is equivalent to A or more and B or less. In the present invention, the "cured coating film" refers to a film made of a cured product of the urethane (meth)acrylate compound, which is formed using the urethane (meth)acrylate compound of the present invention. In the present invention, the term "sheet" conceptually encompasses a sheet and a film.

[0010] [Urethane (meth)acrylate compounds] The urethane (meth)acrylate compound according to this embodiment (hereinafter also referred to as "urethane (meth)acrylate compound (A)") has a structural unit derived from a polyisocyanate compound (a1) (hereinafter also referred to as "structural unit (a1)"), a structural unit derived from a polyol compound (a2) (hereinafter also referred to as "structural unit (a2)"), and a structural unit derived from a hydroxyl group-containing (meth)acrylate compound (a3) ​​(hereinafter also referred to as "structural unit (a3)"). That is, the urethane (meth)acrylate compound (A) is a reaction product of the polyisocyanate compound (a1), the polyol compound (a2), and the hydroxyl group-containing (meth)acrylate compound (a3). The urethane (meth)acrylate compound (A) may, in addition to the structural unit (a1), the structural unit (a2), and the structural unit (a3), optionally further have a structural unit (hereinafter also referred to as "structural unit (a4)") derived from a compound (hereinafter also referred to as "other compound (a4)") other than the polyisocyanate compound (a1), the polyol compound (a2), and the hydroxyl group-containing (meth)acrylate compound (a3), so long as the effects of the present invention are not impaired. The urethane (meth)acrylate compound (A) may contain volatile components such as unreacted polyisocyanate compound (a1), polyol compound (a2) and hydroxyl group-containing (meth)acrylate compound (a3).

[0011] <Polyisocyanate compound (a1)> Examples of the polyisocyanate compound (a1) include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. aliphatic polyisocyanates such as hydrogenated diphenylmethane diisocyanate (methylene bis(cyclohexane-4,1-diyl) bisisocyanate), hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and the like; or trimer compounds or polymer compounds of these polyisocyanates, allophanate type polyisocyanates, biuret type polyisocyanates, water-dispersible polyisocyanates, and the like. Among these, from the viewpoint of increasing the thermal stability of the urethane (meth)acrylate compound, diisocyanate compounds are preferred, aliphatic diisocyanates and alicyclic diisocyanates are more preferred, and aliphatic diisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, and alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, and norbornene diisocyanate are even more preferred. Among these, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, and norbornene diisocyanate are particularly preferred in terms of small curing shrinkage, and hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, and isophorone diisocyanate are more preferred in terms of excellent reactivity and versatility. The polyisocyanate compound (a1) may be used alone or in any combination of two or more kinds in any ratio.

[0012] The content of the structural unit (a1) is preferably 5 to 40 mass%, more preferably 10 to 30 mass%, and even more preferably 13 to 25 mass% based on the total mass of all structural units constituting the urethane (meth)acrylate compound (A). If the content of the structural unit (a1) is equal to or greater than the lower limit, the unreacted polyvalent isocyanate compound (a1) remaining can prevent the active energy ray curable resin composition and coating agent containing the urethane (meth)acrylate compound (A) from becoming highly viscous due to a decrease in storage stability, which is caused by the presence of the remaining unreacted polyvalent isocyanate compound (a1). If the content of the structural unit (a1) is equal to or less than the upper limit, the viscosity of the urethane (meth)acrylate compound (A) does not become excessively high, and a cured coating film having excellent elongation, strength, and elastic modulus can be formed.

[0013] <Polyol compound (a2)> The urethane (meth)acrylate compound (A) has, as the polyol compound (a2), a structural unit (hereinafter also referred to as "structural unit (a2-1)") derived from a polyol compound (a2-1) having a melting point of 15°C or higher and a number average molecular weight of 500 or higher. It is preferable that the urethane (meth)acrylate compound (A) further contains, as the polyol compound (a2), a structural unit (hereinafter also referred to as "structural unit (a2-2)") derived from a polyol compound (a2-2) (excluding the polyol compound (a2-1)) having a molecular weight of 300 or less. When the urethane (meth)acrylate compound (A) contains the structural unit (a2-2), a cured coating film having excellent elongation, strength, and elastic modulus can be formed. That is, the urethane (meth)acrylate compound (A) has at least the structural unit (a1), the structural unit (a2-1), and the structural unit (a3), and preferably further has the structural unit (a2-2) in addition to these. In addition, the urethane (meth)acrylate compound (A) may further have a structural unit (hereinafter also referred to as "structural unit (a2-3)") derived from a polyol compound (a2-3) other than the polyol compound (a2-1) and the polyol compound (a2-2) as necessary within a range that does not impair the effects of the present invention. Examples of the polyol compound (a2-3) include a polyol compound having a melting point of less than 15°C and a molecular weight of more than 300; a polyol compound having a melting point of 15°C or higher and a molecular weight of more than 300 and less than 500, and the like.

[0014] (Polyol compound (a2-1)) The melting point of the polyol compound (a2-1) is 15°C or higher, preferably 17°C or higher, more preferably 20°C or higher, and preferably 100°C or lower, more preferably 90°C or lower, even more preferably 80°C or lower, and particularly preferably 70°C or lower. If the melting point of the polyol compound (a2-1) is above the lower limit, a cured coating film having excellent elongation, less sticky surface, and excellent surface tackiness can be formed. If the melting point of the polyol compound (a2-1) is below the upper limit, a cured coating film having excellent reactivity, less sticky surface, and more excellent surface tackiness can be formed. The above upper and lower limits can be combined in any combination. For example, the melting point of the polyol compound (a2-1) is 15°C or higher, preferably 15 to 100°C, more preferably 15 to 90°C, further preferably 17 to 80°C, and particularly preferably 20 to 70°C.

[0015] The melting point of the polyol compound (a2-1) is a value measured by the following method using a differential scanning calorimeter (DSC). Approximately 10 mg of polyol compound (a2-1) is placed in an aluminum sample container, heated to 200°C at a rate of 10°C / min and held for 5 minutes to melt, then cooled to -100°C at 10°C / min and held for 1 minute. The temperature is again increased at a rate of 10°C / min, held for 5 minutes, and cooled at 10°C / min, and the maximum point of the crystal melting peak observed at this time is taken as the melting point of polyol compound (a2-1). When a commercially available product is used as the polyol compound (a2-1), if a catalog value is available, the catalog value may be used as a simple measured value for the melting point of the polyol compound (a2-1).

[0016] The number average molecular weight (Mn) of the polyol compound (a2-1) is 500 or more, preferably 600 or more, more preferably 1,000 or more, and preferably 10,000 or less, more preferably 8,000 or less, and even more preferably 5,000 or less. If the number average molecular weight (Mn) of the polyol compound (a2-1) is the above lower limit or more, a cured coating film with excellent elongation can be formed. If the number average molecular weight (Mn) of the polyol compound (a2-1) is the above upper limit or less, a cured coating film with excellent strength and elastic modulus can be formed. The above upper and lower limits can be combined in any combination. For example, the number average molecular weight (Mn) of the polyol compound (a2-1) is 500 or more, preferably 500 to 10,000, more preferably 600 to 8,000, and even more preferably 1,000 to 5,000.

[0017] The number average molecular weight (Mn) of the polyol compound (a2-1) is a value calculated from the following formula (1). Number average molecular weight (Mn) = 56110 × number of functional groups (F) / hydroxyl value (mg KOH) (1) In addition, the "number of functional groups (F)" in formula (1) represents the number of hydroxyl groups contained in one molecule. The hydroxyl value of the polyol compound is a value measured in accordance with JIS K 0070:1992.

[0018] The average number of functional groups of the polyol compound (a2-1) is preferably 2.0 or more, and is preferably 5.0 or less, more preferably 4.0 or less. If the average number of functional groups of the polyol compound (a2-1) is the above lower limit or more, it tends to be easy to form a cured coating film that is excellent in heat resistance and has high hardness. If the average number of functional groups of the polyol compound (a2-1) is the above upper limit or less, it tends to be easy to suppress gelation during the reaction, and the storage stability after the reaction tends to be improved. The above upper and lower limits can be combined in any desired manner. For example, the average number of functional groups of the polyol compound (a2-1) is preferably from 2.0 to 5.0, and more preferably from 2.0 to 4.0. The average number of functional groups in the polyol compound (a2-1) is the average number of functional groups per molecule of the polyol compound (a2-1), where the functional group refers to a hydroxyl group.

[0019] Examples of the polyol compound (a2-1) include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols, polyisoprene polyols, (meth)acrylic polyols, polysiloxane polyols, etc. Among these, polyether polyols, polyester polyols, and polycarbonate polyols are preferred, and polyether polyols and polyester polyols are more preferred. The polyol compound (a2-1) may be used alone or in any combination of two or more kinds in any ratio.

[0020] Examples of the polyether polyol include alkylene structure-containing polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol, and random or block copolymers of these polyalkylene glycols.

[0021] Examples of the polyester-based polyols include condensation polymers of polyhydric alcohols and polycarboxylic acids, ring-opening polymers of cyclic esters (lactones), reaction products of three components, a polyhydric alcohol, a polycarboxylic acid, and a cyclic ester, polyols derived from castor oil, polyols in which a portion of ricinoleic acid has been replaced with a fatty acid that has no hydroxyl group, such as oleic acid, and polyols in which the hydroxyl groups of ricinoleic acid have been partially esterified with a monocarboxylic acid.

[0022] Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2,2-dimethylolheptane, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 2,4-diethyl-1,5-pentamethylenediol, hydrogenated bis(methylphenyl)ether Examples of the polyhydric alcohol having three or more functional groups include diols such as phenol A, hydroxyalkylated bisphenol A, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, isosorbide, and 2,2,4-trimethyl-1,3-pentanediol; glycerol, trimethylolmethane, trimethylolethane, trimethylolpropane, trimethylolbutane, 1,2,4-butanetriol, 1,2,3-hexanetriol, 1,2,4-hexanetriol, tris(hydroxymethyl)amine, tris(hydroxyethyl)amine, tris(hydroxypropyl)amine, pentaerythritol, diglycerol, triglycerol, polyglycerol, bis(trimethylolpropane), tris(hydroxymethyl)isocyanurate, tris(hydroxyethyl)isocyanurate, and sugars such as glucose; and sugar derivatives such as sorbitol. The polyhydric alcohol may be used alone or in any combination of two or more kinds in any ratio.

[0023] Examples of the polyvalent carboxylic acid include dicarboxylic acids such as aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids, and polyvalent carboxylic acids having three or more functional groups such as trimellitic acids, pyromellitic acids, and trimesic acids. Examples of the aliphatic dicarboxylic acid include malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Examples of the alicyclic dicarboxylic acid include 1,4-cyclohexanedicarboxylic acid. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, and paraphenylenedicarboxylic acid. The polyvalent carboxylic acid may be used alone or in any combination of two or more kinds in any ratio.

[0024] Examples of the cyclic ester include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone. The cyclic ester may be used alone or in any combination of two or more kinds in any ratio.

[0025] Examples of the polyol derived from castor oil include castor oil and partially dehydrated castor oil. Castor oil is an oil containing a triester compound of ricinoleic acid and glycerin. Approximately 90 mol% of the fatty acids constituting the triester compound of castor oil is ricinoleic acid having a secondary hydroxyl group, and the rest are oleic acid, linoleic acid, linolenic acid, etc., which do not have a hydroxyl group. Therefore, castor oil is a polyol having an average functionality of about 2.7 including a secondary hydroxyl group. Since castor oil is derived from a plant and contains many impurities, it is preferable to use castor oil that has been purified by distillation or the like. Since castor oil contains fatty acids having unsaturated bonds such as ricinoleic acid, it is also preferable to use hydrogenated castor oil.

[0026] Examples of the polycarbonate-based polyol include a reaction product of a polyhydric alcohol with phosgene, and a ring-opening polymer of a cyclic carbonate (such as an alkylene carbonate).

[0027] Examples of the polyhydric alcohol used in the polycarbonate-based polyol include the polyhydric alcohols exemplified above in the explanation of the polyester-based polyol. Examples of the alkylene carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, hexamethylene carbonate, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, and diphenyl carbonate. The polycarbonate-based polyol may be any compound having a carbonate bond in the molecule and a hydroxyl group at the end, and may have an ester bond in addition to the carbonate bond.

[0028] The polyolefin polyols include, for example, those having a homopolymer or copolymer of ethylene, propylene, butene, or the like as a saturated hydrocarbon skeleton and having hydroxyl groups at the molecular terminals.

[0029] The polybutadiene-based polyols include, for example, those having a butadiene copolymer as a hydrocarbon skeleton and having hydroxyl groups at the molecular terminals. The polybutadiene-based polyol may be a hydrogenated polybutadiene polyol in which all or a part of the ethylenically unsaturated groups contained in the structure thereof have been hydrogenated.

[0030] The polyisoprene-based polyols include, for example, those having an isoprene copolymer as a hydrocarbon backbone and having hydroxyl groups at the molecular terminals. The polyisoprene-based polyol may be a hydrogenated polyisoprene polyol in which all or a part of the ethylenically unsaturated groups contained in the structure have been hydrogenated.

[0031] The (meth)acrylic polyol may, for example, be one having two or more hydroxyl groups in the molecule of a polymer or copolymer of alkyl (meth)acrylate. Examples of such alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0032] Examples of the polysiloxane polyol include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

[0033] The content of the structural unit (a2-1) is preferably 59.5 to 90 mass%, more preferably 65 to 85 mass%, and even more preferably 73 to 81 mass% based on the total mass of all structural units constituting the urethane (meth)acrylate compound (A). If the content of the structural unit (a2-1) is equal to or greater than the above lower limit, the viscosity of the urethane (meth)acrylate compound (A) does not become excessively high, and a cured coating film having excellent elongation, strength, and elastic modulus can be formed. If the content of the structural unit (a2-1) is equal to or less than the above upper limit, the unreacted polyol compound (a2-1) remaining in the active energy ray curable resin composition and coating agent containing the urethane (meth)acrylate compound (A) can be prevented from increasing in viscosity due to a decrease in storage stability, and from a decrease in strength of the cured coating film.

[0034] (Polyol compound (a2-2)) The molecular weight of the polyol compound (a2-2) is 300 or less, preferably 250 or less, more preferably 200 or less. If the molecular weight of the polyol compound (a2-2) is the above upper limit or less, a cured coating film having excellent strength and elastic modulus can be formed. The lower limit of the molecular weight of the polyol compound (a2-2) is not particularly limited, but is preferably 50 or more, more preferably 55 or more, and even more preferably 60 or more. The upper and lower limits can be combined in any combination. For example, the number average molecular weight (Mn) of the polyol compound (a2-2) is 300 or less, preferably 50-300, more preferably 55-250, and even more preferably 60-200.

[0035] Examples of the polyol compound (a2-2) include aliphatic polyols and alicyclic polyols. The polyol compound (a2-2) may be used alone or in any combination of two or more kinds in any ratio.

[0036] Examples of aliphatic polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol (1,3-propanediol), dimethylolpropane, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, Examples of the alcohols include aliphatic alcohols containing two hydroxyl groups, such as 1,5-pentamethylene diol, 1,6-hexamethylene diol, 3-methyl-1,5-pentamethylene diol, 2,4-diethyl-1,5-pentamethylene diol, pentaerythritol diacrylate, 1,9-nonanediol, and 2-methyl-1,8-octanediol; sugar alcohols, such as xylitol and sorbitol; and aliphatic alcohols containing three or more hydroxyl groups, such as glycerin, trimethylolpropane, and trimethylolethane. Examples of alicyclic polyols include cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyldimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecane dimethanol.

[0037] The content of the structural unit (a2-2) is preferably 0.1 to 15 mass%, more preferably 0.1 to 10 mass%, and even more preferably 0.3 to 8 mass% based on the total mass of all structural units constituting the urethane (meth)acrylate compound (A). If the content of the structural unit (a2-2) is equal to or more than the above lower limit, the viscosity of the urethane (meth)acrylate compound (A) does not become excessively high, and a cured coating film having excellent elongation, strength, and elastic modulus can be formed. If the content of the structural unit (a2-2) is equal to or less than the above upper limit, the unreacted polyol compound (a2-2) remaining in the active energy ray curable resin composition and coating agent containing the urethane (meth)acrylate compound (A) can be prevented from increasing in viscosity due to a decrease in storage stability, and from a decrease in strength of the cured coating film.

[0038] The total content of the structural unit (a2-1) and the structural unit (a2-2) is preferably 59.5 to 94.5% by mass, more preferably 65 to 88.5% by mass, and even more preferably 73 to 85% by mass, based on the total mass of all structural units constituting the urethane (meth)acrylate compound (A). If the total content of the structural unit (a2-1) and the structural unit (a2-2) is equal to or greater than the lower limit, the viscosity of the urethane (meth)acrylate compound (A) does not become excessively high, and a cured coating film having excellent elongation, strength, and elastic modulus can be formed. If the total content of the structural unit (a2-1) and the structural unit (a2-2) is equal to or less than the upper limit, the remaining unreacted polyol compound (a2) can be used to suppress the increase in viscosity due to the decrease in storage stability of the active energy ray curable resin composition and coating agent containing the urethane (meth)acrylate compound (A) and the decrease in strength of the cured coating film.

[0039] As the polyol (a2) as a whole, it is preferable to use a difunctional polyol since it can impart extensibility to a cured coating film, and further, a difunctional polyol and a trifunctional polyol may be used in combination.

[0040] <Hydroxyl group-containing (meth)acrylate compound (a3)> The hydroxyl group-containing (meth)acrylate compound (a3) ​​is a compound having a hydroxyl group and a (meth)acryloyl group. The number of hydroxyl groups is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1. The number of (meth)acryloyl groups is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2.

[0041] Examples of the hydroxyl group-containing (meth)acrylate compound (a3) ​​include hydroxyl group-containing (meth)acrylates having one ethylenically unsaturated group, hydroxyl group-containing (meth)acrylates having two ethylenically unsaturated groups, and hydroxyl group-containing (meth)acrylates having three or more ethylenically unsaturated groups. The hydroxyl group-containing (meth)acrylate compound (a3) ​​may be used alone or in any combination of two or more kinds in any ratio.

[0042] Examples of the hydroxyl group-containing (meth)acrylate having one ethylenically unsaturated group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol mono(meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate.

[0043] Examples of hydroxyl-containing (meth)acrylates having two ethylenically unsaturated groups include glycerin di(meth)acrylate and 2-hydroxy-3-acryloyl-oxypropyl methacrylate.

[0044] Examples of hydroxyl group-containing (meth)acrylates containing three or more ethylenically unsaturated groups include pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified dipentaerythritol penta(meth)acrylate.

[0045] Among these, hydroxyl group-containing (meth)acrylates having one ethylenically unsaturated group are preferred, hydroxyalkyl (meth)acrylates are more preferred, hydroxyalkyl (meth)acrylates in which the alkyl group has 1 to 4 carbon atoms are even more preferred, and 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are particularly preferred.

[0046] The content of the structural unit (a3) ​​is preferably 0.5 to 10 mass%, more preferably 1.5 to 8 mass%, and even more preferably 2 to 5 mass%, based on the total mass of all structural units constituting the urethane (meth)acrylate compound (A). When the content of the structural unit (a3) ​​is equal to or more than the lower limit, a decrease in the elongation of the cured coating film due to an increase in the number of (meth)acrylate functional groups can be suppressed. When the content of the structural unit (a3) ​​is equal to or less than the upper limit, a decrease in the strength of the cured coating film due to a decrease in the number of (meth)acrylate functional groups can be suppressed.

[0047] <Other compounds (a4)> Examples of the other compounds (a4) include monools. The other compound (a4) may be used alone or in any combination of two or more kinds in any ratio.

[0048] The content of the structural unit (a4) is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total mass of all structural units constituting the urethane (meth)acrylate compound (A). The lower limit of the content of the structural unit (a4) is preferably 0% by mass. The total content of the structural units (1), (a2), (a3) ​​and (a4), i.e., the total content of the structural units (1), (a2-1), (a2-2), (a2-3), (a3) ​​and (a4), is 100 mass%.

[0049] <Weight average molecular weight> The weight average molecular weight (Mw) of the urethane (meth)acrylate compound (A) is preferably 10,000 to 100,000, more preferably 12,000 to 80,000, and even more preferably 15,000 to 60,000. If the weight average molecular weight of the urethane (meth)acrylate compound (A) is equal to or greater than the above lower limit, a cured coating film having superior elongation, strength, and elastic modulus can be formed. If the weight average molecular weight of the urethane (meth)acrylate compound (A) is equal to or less than the above upper limit, the viscosity of the active energy ray curable resin composition and coating agent containing the urethane (meth)acrylate compound (A) is unlikely to be excessively high, and therefore, the handling property is excellent, and the coating agent is unlikely to gel.

[0050] The weight average molecular weight (Mw) of the urethane (meth)acrylate compound (A) is a weight average molecular weight calculated based on the molecular weight of standard polystyrene. For example, the weight average molecular weight was measured using a high performance liquid chromatography (manufactured by Japan Waters, Inc., "Waters 2695 (main body)" and "Waters 2414 (detector)") with a column: Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 7 , Separation range: 100~2×10 7 The measurement is performed using three columns in series (theoretical plate number: 10,000 plates / column, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm).

[0051] <Method for producing urethane (meth)acrylate compound (A)> The urethane (meth)acrylate compound (A) can be obtained by reacting a polyisocyanate compound (a1), a polyol compound (a2), and a hydroxyl group-containing (meth)acrylate compound (a3), and, if necessary, another compound (a4). An example of a method for producing the urethane (meth)acrylate compound (A) includes a step of reacting a polyisocyanate compound (a1), a polyol compound (a2-1), a hydroxyl group-containing (meth)acrylate compound (a3), and, if necessary, one or more of a polyol compound (a2-2) and other compounds (a4).

[0052] When the total amount of the polyisocyanate compound (a1), the polyol compound (a2-1), the polyol compound (a2-2), the hydroxyl group-containing (meth)acrylate compound (a3) ​​and the other compounds (a4) is taken as 100 mass%, the proportion of each component is as follows. The proportion of the polyisocyanate compound (a1) is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 13 to 25% by mass. If the proportion of the polyisocyanate compound (a1) is equal to or greater than the lower limit, the unreacted polyisocyanate compound (a1) remaining in the active energy ray curable resin composition and coating agent containing the urethane (meth)acrylate compound (A) can be prevented from increasing in viscosity due to a decrease in storage stability. If the proportion of the polyisocyanate compound (a1) is equal to or less than the upper limit, the viscosity of the urethane (meth)acrylate compound (A) does not become excessively high, and a cured coating film having excellent elongation, strength, and elastic modulus can be formed.

[0053] The proportion of the polyol compound (a2-1) is preferably from 59.5 to 90 mass %, more preferably from 65 to 85 mass %, and even more preferably from 73 to 81 mass %. The proportion of the polyol compound (a2-2) is preferably from 0.1 to 15 mass %, more preferably from 0.1 to 10 mass %, and even more preferably from 0.3 to 8 mass %. The total proportion of the polyol compound (a2-1) and the polyol compound (a2-1) is preferably from 59.5 to 94.5 mass %, more preferably from 65 to 88.5 mass %, and even more preferably from 73 to 85 mass %. If these ratios are equal to or greater than the lower limit, the viscosity of the urethane (meth)acrylate compound (A) does not become excessively high, and a cured coating film having excellent elongation, strength, and elastic modulus can be formed. If these ratios are equal to or less than the upper limit, the remaining unreacted polyol compound (a2) can suppress the increase in viscosity due to the decrease in storage stability of the active energy ray-curable resin composition and coating agent containing the urethane (meth)acrylate compound (A) and the decrease in strength of the cured coating film.

[0054] The proportion of the hydroxyl-containing (meth)acrylate compound (a3) ​​is preferably 0.5 to 10 mass%, more preferably 1.5 to 8 mass%, and even more preferably 2 to 5 mass%. When the proportion of the hydroxyl-containing (meth)acrylate compound (a3) ​​is equal to or greater than the lower limit, a decrease in the elongation of the cured coating film due to an increase in the number of (meth)acrylate functional groups can be suppressed. When the proportion of the hydroxyl-containing (meth)acrylate compound (a3) ​​is equal to or less than the upper limit, a decrease in the strength of the cured coating film due to a decrease in the number of (meth)acrylate functional groups can be suppressed. The proportion of the other compound (a4) is preferably from 0 to 20 mass %, more preferably from 0 to 10 mass %, and even more preferably from 0 to 5 mass %.

[0055] Examples of the method for reacting the polyisocyanate compound (a1), the polyol compound (a2), and the hydroxyl group-containing (meth)acrylate compound (a3) ​​include the following methods (i) to (iii). Method (i): A method in which a polyisocyanate compound (a1), a polyol compound (a2-1), a hydroxyl group-containing (meth)acrylate compound (a3), and, if necessary, a polyol compound (a2-2) are charged into a reactor all at once or separately and reacted. Method (ii): A method in which a polyisocyanate compound (a1), a polyol compound (a2-1), and, if necessary, a polyol compound (a2-2) are reacted with the resulting urethane compound (a12) having a terminal isocyanate group, and a hydroxyl group-containing (meth)acrylate compound (a3). Method (iii): A method of reacting a polyisocyanate compound (a1) with a hydroxyl group-containing (meth)acrylate compound (a3), and reacting the resulting reaction product (a13) with a polyol compound (a2-1) and, if necessary, a polyol compound (a2-2).

[0056] Among the methods (i) to (iii), the method (ii) is preferred from the viewpoint of reducing by-products in the reaction, and the method (iii) is preferred from the viewpoint of reaction stability. For example, the reaction can be terminated when the residual isocyanate group content in the reaction system becomes 0.1 mass % or less, thereby obtaining the urethane (meth)acrylate compound (A).

[0057] The reactions of the methods (i) to (iii) are preferably carried out in the presence of a catalyst for the purpose of promoting the reaction. Examples of the catalyst include organometallic compounds, metal salts, amine catalysts, and bismuth catalysts. The catalyst may be used alone or in any combination of two or more kinds in any ratio.

[0058] Examples of the organometallic compound include dibutyltin dilaurate, trimethyltin hydroxide, and tetra-n-butyltin. Examples of the metal salt include zinc octoate, tin octoate, cobalt naphthenate, stannous chloride, and stannic chloride. Examples of the amine catalyst include triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N',N'-tetramethyl-1,3-butanediamine, and N-ethylmorpholine. Examples of the bismuth catalyst include bismuth nitrate, bismuth bromide, bismuth iodide, bismuth sulfide, and the like; as well as organic bismuth compounds such as dibutyl bismuth dilaurate and dioctyl bismuth dilaurate; and organic acid bismuth salts such as bismuth 2-ethylhexanoate, bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth tribisneodecanoate, bismuth disalicylate, and bismuth digallate. Among these, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferable.

[0059] In the reactions of methods (i) to (iii), an organic solvent having no functional group reactive with an isocyanate group may be used. Examples of the organic solvent include esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as toluene and xylene. The organic solvent may be used alone or in any combination of two or more kinds in any ratio.

[0060] The reaction temperature is preferably from 30 to 90°C, more preferably from 40 to 80°C. The reaction time is preferably from 2 to 12 hours, more preferably from 3 to 10 hours.

[0061] <Action and effect> The urethane (meth)acrylate compound (A) of this embodiment contains the above-mentioned structural unit (a1), structural unit (a2) and structural unit (a3), and therefore can form a cured coating film with an excellent balance between elongation and surface tackiness. Specifically, the urethane (meth)acrylate compound (A) of this embodiment can easily form a cured coating film having an elongation of 200% or more at 23°C in a tensile test and a tack value of 1.0 or less at 23°C in a probe tack test.

[0062] The cured coating film is a film formed by using the urethane (meth)acrylate compound (A) and made of a cured product of the urethane (meth)acrylate compound (A). The cured coating film is formed, for example, by applying the urethane (meth)acrylate compound (A) onto a substrate so that the film thickness after curing is 100 μm, drying as necessary, and then irradiating with active energy rays. Examples of the method for applying the urethane (meth)acrylate compound (A) include wet coating methods such as spray, shower, dipping, roll, spin, curtain, flow, slit, die, gravure, comma, dispenser, screen printing, and inkjet printing. Examples of the active energy rays to be irradiated include light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays, electromagnetic waves such as X-rays and γ-rays, as well as electron beams, proton beams, neutron beams, etc. Among these, ultraviolet rays are preferred.

[0063] The elongation (elongation rate) of a cured coating film having a thickness of 100 μm at 23° C. in a tensile test is preferably 200% or more, more preferably 210% or more, and even more preferably 220% or more. There is no particular upper limit to the elongation, but it is preferably, for example, 500%. The elongation of the cured coating film is a value measured by a tensile test, specifically, in accordance with JIS K 7127:1999, at a tensile speed of 10 mm / min and a measurement temperature of 23°C.

[0064] The tack value of a cured coating film having a thickness of 100 μm at 23° C. in a probe tack test is preferably 1.0 or less, more preferably 0.7 or less, and even more preferably 0.5 or less. There is no particular restriction on the lower limit of the tack value, but it is preferably, for example, 0.01. The tack value of the cured coating film is a value measured by a probe tack test. Specifically, a probe tack tester was used, with a probe diameter of φ5.05 mm, a pressing speed of 1.0 cm / s, a peeling speed of 1.0 cm / s, and a contact load of 1000 gf / cm 2 This value is measured under the measurement conditions of a contact time of 5.0 seconds.

[0065] The glass transition temperature of a cured coating film having a thickness of 100 μm is preferably 0° C. or lower, more preferably −10° C. or lower, and even more preferably −20° C. or lower. There is no particular restriction on the lower limit of the glass transition temperature, but it is preferably −130° C., for example. When the glass transition temperature of the cured coating film is equal to or lower than the above upper limit, the adhesion of the cured coating film to the substrate tends to be improved. The glass transition temperature of the cured coating film is a value measured by dynamic viscoelasticity measurement. Specifically, using a dynamic viscoelasticity measurement device, the storage modulus (E') and loss modulus (E") of the cured coating film are measured in a tensile mode in accordance with ISO6721-4:2019 under the conditions of an initial chuck distance of 2.0 cm, a measurement frequency of 1 Hz, a measurement temperature range of -150 to 200°C, a heating rate of 3°C / min, and a nitrogen gas flow of 8 mL / min. Tan δ (loss tangent) at each temperature is calculated from the formula tan δ = E" / E', and the temperature showing the maximum value of tan δ is regarded as the glass transition temperature of the cured coating film.

[0066] [Active energy ray-curable resin composition] The active energy ray-curable resin composition of the present embodiment contains the above-mentioned urethane (meth)acrylate compound (A). The content of the urethane (meth)acrylate compound (A) relative to the total mass of the active energy ray curable resin composition is preferably 0.5 to 100 mass%, more preferably 1 to 100 mass%, further preferably 3 to 100 mass%, and particularly preferably 5 to 100 mass%. If the content of the urethane (meth)acrylate compound (A) is equal to or greater than the above lower limit, sufficient film-forming properties tend to be obtained. If the content of the urethane (meth)acrylate compound (A) is equal to or less than the above upper limit, the increase in viscosity of the active energy ray curable resin composition can be suppressed, and good coatability tends to be maintained.

[0067] The active energy ray-curable resin composition may consist only of the urethane (meth)acrylate compound (A). However, it is preferable that the active energy ray-curable resin composition contains, in addition to the urethane (meth)acrylate compound (A), an ethylenically unsaturated monomer (B) (excluding the urethane (meth)acrylate compound (A)). The active energy ray-curable resin composition preferably contains a photopolymerization initiator (C). The active energy ray-curable resin composition may further contain, as necessary, components other than the urethane (meth)acrylate compound (A), the ethylenically unsaturated monomer (B), and the photopolymerization initiator (C) (hereinafter, also referred to as "optional components"), as long as the effects of the present invention are not impaired.

[0068] <Ethylenically unsaturated monomer (B)> The ethylenically unsaturated monomer (B) may be any ethylenically unsaturated monomer having one or more ethylenically unsaturated groups in one molecule, and examples thereof include monofunctional monomers, bifunctional monomers, trifunctional or higher functional monomers, etc. However, the ethylenically unsaturated monomer (B) does not include the urethane (meth)acrylate compound (A). The ethylenically unsaturated monomer (B) may be used alone or in any combination of two or more kinds in any ratio.

[0069] The monofunctional monomer may be any monomer containing one ethylenically unsaturated group, and examples thereof include styrene, vinyl toluene, chlorostyrene, α-methylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, acrylonitrile, vinyl acetate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-phenoxy-2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxypropyl ... 2-Hydroxypropyl (meth)acrylate, 2-Hydroxy-3-phenoxypropyl (meth)acrylate, 3-Chloro-2-Hydroxypropyl (meth)acrylate, Glycerin Mono(meth)acrylate, Glycidyl (meth)acrylate, Lauryl (meth)acrylate, Cyclohexyl (meth)acrylate, Isobornyl (meth)acrylate, Tricyclodecanyl (meth)acrylate, Dicyclopentenyl (meth)acrylate, N-Butyl (meth)acrylate, Hexyl (meth)acrylate, Heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, benzyl (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, nonylphenol propylene oxide modified (meth)acrylate, half ester (meth)acrylates of phthalic acid derivatives such as 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, etc. acrylate, tetrahydrofurfuryl (meth)acrylate, carbitol (meth)acrylate, benzyl (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, allyl (meth)acrylate, acryloylmorpholine, 2-hydroxyethyl acrylamide, N-methylol (meth)acrylamide, N-vinylpyrrolidone, 2-vinylpyridine, 2-(meth)acryloyloxyethyl acid phosphate monoester, and the like.

[0070] The bifunctional monomer may be any monomer containing two ethylenically unsaturated groups, and examples thereof include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide modified bisphenol A type di(meth)acrylate, propylene oxide modified bisphenol A type di(meth)acrylate, 1 ,6-hexanediol di(meth)acrylate, 1,6-hexanediol ethylene oxide modified di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, hydroxypivalic acid modified neopentyl glycol di(meth)acrylate, isocyanuric acid ethylene oxide modified diacrylate, 2-(meth)acryloyloxyethyl acid phosphate diester, and the like.

[0071] The trifunctional or higher functional monomer may be any monomer containing three or more ethylenically unsaturated groups, and examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, isocyanuric acid ethylene oxide modified triacrylate, ethylene oxide modified dipentaerythritol penta(meth)acrylate, and the like. Examples of the poly(meth)acrylate include dipentaerythritol penta(meth)acrylate, ethylene oxide modified dipentaerythritol hexa(meth)acrylate, ethylene oxide modified pentaerythritol tri(meth)acrylate, ethylene oxide modified pentaerythritol tetra(meth)acrylate, caprolactone modified dipentaerythritol penta(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate, caprolactone modified pentaerythritol tri(meth)acrylate, caprolactone modified pentaerythritol tetra(meth)acrylate, and succinic acid modified pentaerythritol tri(meth)acrylate.

[0072] As the ethylenically unsaturated monomer (B), a urethane (meth)acrylate compound obtained by reacting a polyisocyanate compound with a (meth)acrylate compound containing one hydroxyl group, or a urethane (meth)acrylate compound obtained by reacting a polyisocyanate compound, a (meth)acrylate compound containing one hydroxyl group, and a polyol compound (excluding the urethane (meth)acrylate compound (A)) may be used.

[0073] Among these, as the ethylenically unsaturated monomer (B), a monofunctional monomer is preferable, an alicyclic monofunctional monomer is more preferable, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate is further preferable, and isobornyl (meth)acrylate is particularly preferable.

[0074] The ethylenically unsaturated monomer (B) may be added separately to the urethane (meth)acrylate compound (A), or a part or all of the ethylenically unsaturated monomer (B) may be present in the reaction system during the production of the urethane (meth)acrylate compound (A). The ethylenically unsaturated monomer (B) may be the one used as a reaction solvent during the production of the urethane (meth)acrylate compound (A).

[0075] The content of the ethylenically unsaturated monomer (B) in the active energy ray curable resin composition is preferably 20 to 400 parts by mass, more preferably 30 to 300 parts by mass, further preferably 40 to 200 parts by mass, particularly preferably 50 to 150 parts by mass, and most preferably 60 to 100 parts by mass, relative to 100 parts by mass of the urethane (meth)acrylate compound (A). If the content of the ethylenically unsaturated monomer (B) is within the above range, sufficient adhesion to a substrate tends to be easily obtained when the active energy ray curable resin composition is used as a coating agent.

[0076] <Photopolymerization initiator (C)> The active energy ray-curable resin composition according to the embodiment preferably contains a photopolymerization initiator (C) in order to more efficiently carry out curing with active energy rays. The photopolymerization initiator (C) is not particularly limited as long as it generates radicals by the action of light, and examples thereof include acetophenones, benzoins, benzophenones, thioxanthones, and acylphosphonoxides. The photopolymerization initiator (C) may be used alone or in any combination of two or more kinds in any ratio.

[0077] Examples of acetophenones include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)-phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propanone oligomer, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, phenylglyoxylic acid methyl ester, and the like.

[0078] Examples of benzoins include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether. Preferred examples of benzophenones include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, and (4-benzoylbenzyl)trimethylammonium chloride.

[0079] Examples of thioxanthones include 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride, and the like. Examples of the acylphosphonoxides include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0080] When the photopolymerization initiator (C) is used, an auxiliary may be used in combination. Examples of the auxiliary include triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. Among these, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin isopropyl ether, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one are preferred. The auxiliary may be used alone or in any combination of two or more kinds in any ratio.

[0081] The content of the photopolymerization initiator (C) in the active energy ray curable resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the total of the urethane (meth)acrylate compound (A) and the ethylenically unsaturated monomer (B). If the content of the photopolymerization initiator (C) is equal to or greater than the lower limit, curing tends to be good. If the content of the photopolymerization initiator (C) is equal to or less than the upper limit, precipitation is unlikely to occur when applied, the solution stability is excellent, and problems such as embrittlement and coloration tend to be unlikely to occur.

[0082] <Optional ingredients> Examples of the optional components include a surface conditioner, a leveling agent, a polymerization inhibitor, and an organic solvent. The surface conditioner is not particularly limited, but examples thereof include alkyd resins, etc. Alkyd resins have the effect of imparting film-forming properties during coating and the effect of increasing adhesion to a thin metal film surface. The surface conditioner may be used alone or in any combination of two or more kinds in any ratio.

[0083] As the leveling agent, any known leveling agent can be used as long as it has the effect of imparting wettability to the substrate and reducing the surface tension of the coating liquid. Examples of such leveling agents include silicone-modified resins, fluorine-modified resins, and alkyl-modified resins. The leveling agent may be used alone or in any combination of two or more kinds in any ratio.

[0084] Examples of the polymerization inhibitor include p-benzoquinone, naphthoquinone, toluquinone, 2,5-diphenyl-p-benzoquinone, hydroquinone, 2,5-di-t-butylhydroquinone, methylhydroquinone, methoxyphenol, 2,6-di-t-butyl-p-cresol, mono-t-butylhydroquinone, pt-butylcatechol, etc. Among these, methoxyphenol and 2,6-di-t-butyl-p-cresol are preferred. The polymerization inhibitor may be used alone or in any combination of two or more kinds in any ratio.

[0085] Examples of the organic solvent include alcohols such as methanol, ethanol, propanol, n-butanol, and i-butanol; ketones such as acetone, methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; cellosolves such as ethyl cellosolve; aromatics such as toluene and xylene; glycol ethers such as propylene glycol monomethyl ether; acetates such as methyl acetate, ethyl acetate, and butyl acetate; and diacetone alcohol. The organic solvent may be used alone or in any combination of two or more kinds in any ratio.

[0086] In addition to the above, optional components such as antioxidants, flame retardants, antistatic agents, fillers, stabilizers, reinforcing agents, matting agents, and abrasives may be used.

[0087] <Manufacturing method> In producing the active energy ray curable composition, the method of mixing the urethane (meth)acrylate compound (A), the ethylenically unsaturated monomer (B), the photopolymerization initiator (C) and the optional components is not particularly limited, and they can be mixed by various methods. For example, each component may be mixed at once, or two or more of the urethane (meth)acrylate compound (A), the ethylenically unsaturated monomer (B), the photopolymerization initiator (C) and the optional components may be mixed, and then the remaining components may be mixed.

[0088] <Curing> When the active energy ray-curable resin composition is used for various applications, it is applied onto various substrates or members and cured by irradiating the composition with active energy rays.

[0089] Examples of substrates to which the active energy ray-curable resin composition is applied include resin molded products such as films, sheets, and cups, metal substrates, glass, and composite substrates thereof. Examples of resins that can be used to form the resin molded product include polyolefin resins, polyester resins, polycarbonate resins, acrylonitrile butadiene styrene copolymers (ABS), polystyrene resins, and polyamide resins. Examples of the metal substrate include a metal deposition layer and a metal plate (copper, stainless steel (SUS304, SUSBA, etc.), aluminum, zinc, magnesium, etc.).

[0090] The method for applying the active energy ray-curable resin composition is not particularly limited, and examples thereof include wet coating methods such as spray, shower, dipping, roll, spin, curtain, flow, slit, die, gravure, comma, dispenser, screen printing, and inkjet printing. When the active energy ray-curable resin composition is a solid or a high-viscosity liquid, a hot melt method in which the active energy ray-curable resin composition is heated to reduce the viscosity and then coated by the above-mentioned method may be used.

[0091] When the active energy ray-curable resin composition contains an organic solvent, it is preferable to dry and remove the organic solvent before irradiation with active energy rays. The drying temperature is preferably from 40 to 120°C, and more preferably from 50 to 100°C. The drying time is preferably from 1 to 20 minutes, more preferably from 2 to 10 minutes.

[0092] Examples of the active energy rays to be irradiated include light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X-rays and gamma rays, as well as electron beams, proton beams, neutron beams, etc. Curing by ultraviolet irradiation is advantageous in terms of curing speed, ease of availability of irradiation equipment, cost, etc. The active energy ray-curable resin composition according to this embodiment can be cured without using a photopolymerization initiator (C) when irradiated with an electron beam.

[0093] The method of curing by ultraviolet irradiation may be, for example, using a high-pressure mercury lamp, ultra-high-pressure mercury lamp, carbon arc lamp, metal halide lamp, xenon lamp, chemical lamp, electrodeless discharge lamp, LED, or the like that emits light in the wavelength range of 150 to 450 nm, with an intensity of 30 to 3,000 mJ / cm. 2 Irradiation is performed to a degree. After the ultraviolet irradiation, heating may be carried out as necessary to complete the curing.

[0094] The thickness of the coating film after curing is preferably from 1 to 300 μm, more preferably from 2 to 250 μm, and even more preferably from 5 to 200 μm.

[0095] <Application> The use of the active energy ray-curable resin composition according to the present embodiment is not particularly limited, and is suitable as various coating film-forming materials, for example, protective coating agents, anchor coating agents, coating agents for hard coats, paints, inks, magnetic powder coating binders, coatings for sandblasting, pressure sensitive adhesives, adhesives, tackifiers, printing plates, and the like. In particular, the cured product of the active energy ray-curable resin composition according to this embodiment is not sticky and has excellent elongation, and is therefore extremely useful as a coating agent.

[0096] [Coating agent] The coating agent of the present embodiment contains the above-mentioned active energy ray-curable resin composition. The coating agent may consist of only the active energy ray-curable resin composition, or may contain, in addition to the active energy ray-curable resin composition, components other than the active energy ray-curable resin composition (hereinafter, also referred to as "other components").

[0097] The coating agent preferably contains the above-mentioned urethane (meth)acrylate compound (A) in an amount of 5 to 100 mass% based on the total mass of the coating agent, more preferably 5 to 99 mass%, even more preferably 10 to 95 mass%, particularly preferably 15 to 90 mass%, and most preferably 55 to 90 mass%. If the content of the urethane (meth)acrylate compound (A) is equal to or greater than the above lower limit, sufficient film-forming properties tend to be obtained. If the content of the urethane (meth)acrylate compound (A) is equal to or less than the above upper limit, the viscosity of the coating agent tends to be suppressed from increasing, and good coatability tends to be maintained.

[0098] Examples of other components include urethane (meth)acrylates other than the urethane (meth)acrylate compound (A) (hereinafter also referred to as "other urethane (meth)acrylates"), ethylenically unsaturated monomers, diluting solvents, (meth)acrylic resins, and the like. The other components may be used alone or in any combination of two or more kinds in any ratio.

[0099] Sheet The sheet of the present embodiment includes a cured product of the above-mentioned active energy ray-curable resin composition. The sheet can be produced, for example, by coating an active energy ray-curable resin composition on a substrate, drying the composition if necessary, irradiating the substrate with active energy rays to cure the active energy ray-curable resin composition on the substrate, and then peeling the composition off. The method for curing the active energy ray-curable resin composition is as described above. EXAMPLES

[0100] The present invention will be described in more detail below with reference to examples. In the examples and comparative examples, "parts" refers to "parts by mass" unless otherwise specified, and "%" refers to "% by mass" unless otherwise specified. Evaluations in the examples and comparative examples were performed by the following methods. The following examples are illustrative of the present invention and are not intended to limit the scope of the present invention.

[0101] [Raw materials] <Polyisocyanate compound (a1)> ·A1-1: Methylenebis(cyclohexane-4,1-diyl)bisisocyanate. ·A1-2: Isophorone diisocyanate.

[0102] <Polyol compound (a2-1) and its comparative products> · a2-1-1: Polyether polyol (polyethylene glycol, hydroxyl value 38.6, average functionality 2.0, melting point 21°C, number average molecular weight (Mn) 2,900). · a2-1-2: Polyester polyol (hydroxyl value 58.1, average functionality 2.0, melting point 54°C, number average molecular weight (Mn) 1,900). · a2-1-3: Polyether polyol (polyethylene glycol, hydroxyl value 56.9, average functionality 2.0, melting point 21°C, number average molecular weight (Mn) 2,000). a2-1-4 (comparison product): Polyether polyol (polyethylene glycol, hydroxyl value 56.1, average functionality 2.0, melting point -35°C, number average molecular weight (Mn) 2,000). a2-1-5 (comparison product): Polyester polyol (hydroxyl value 62.1, average functionality 2.0, melting point -65°C, number average molecular weight (Mn) 1,800).

[0103] <Polyol compound (a2-2)> · a2-2-1: 1,3-propanediol (melting point -27℃, molecular weight 76.1). · a2-2-2: 2,2-dimethyl-1,3-propanediol (melting point 130°C, molecular weight 104.1).

[0104] <Hydroxyl group-containing (meth)acrylate compound (a3)> ·A3-1: 2-hydroxyethyl acrylate.

[0105] [Measurement and Evaluation] <Measurement of number average molecular weight (Mn)> The number average molecular weight (Mn) of the polyol compound was calculated from the following formula (1). Number average molecular weight (Mn) = 56110 × number of functional groups (F) / hydroxyl value (mg KOH) (1) In addition, the "number of functional groups (F)" in formula (1) represents the number of hydroxyl groups contained in one molecule. The hydroxyl value of the polyol compound was measured in accordance with JIS K 0070:1992.

[0106] <Measurement of weight average molecular weight (Mw)> The weight average molecular weight (Mw) of the urethane acrylate compound was measured using a high performance liquid chromatography (manufactured by Japan Waters, "Waters 2695 (main unit)" and "Waters 2414 (detector)") with a Shodex GPC KF-806L column (exclusion limit molecular weight: 2 × 10 7 , Separation range: 100~2×10 7 The theoretical number of plates: 10,000 plates / plate, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) was used in series, and the measurements were expressed as values ​​converted into standard polystyrene molecular weights.

[0107] <Evaluation of cured coating film> (Preparation of sample pieces for evaluation) The urethane acrylate compound was applied to a heavy-release PET film using an applicator so that the film thickness after drying would be 100 μm, and then dried at 60 °C for 30 minutes. The film was then irradiated with ultraviolet light from a height of 18 cm at a conveyor speed of 5.1 m / min using one high-pressure mercury lamp in two passes (cumulative irradiation amount 800 mJ / cm 2 ) was performed to form a cured coating film on the heavy release PET film. Next, this cured coating film was punched out with a dumbbell to prepare a rectangular sample having a width of 15 mm and a length of 75 mm, and the cured coating film was peeled off from the heavy release PET film to prepare a sample piece for evaluation.

[0108] (Measurement of glass transition temperature) The glass transition temperature of the cured coating film is a value measured by dynamic viscoelasticity measurement. Specifically, a dynamic viscoelasticity measuring device (manufactured by UBM Corporation, product name "Rheogel-E4000") was used to measure the storage modulus (E') and loss modulus (E") of the evaluation sample piece in tensile mode in accordance with ISO6721-4:2019 under the conditions of an initial chuck distance of 2.0 cm, a measurement frequency of 1 Hz, a measurement temperature range of -150 to 200 °C, a heating rate of 3 °C / min, and a nitrogen gas flow of 8 mL / min. Tan δ (loss tangent) at each temperature was calculated from the formula tan δ = E" / E', and the temperature showing the maximum value of tan δ was determined as the glass transition temperature of the cured coating film.

[0109] (Measurement of tack value) A probe tack measuring device (manufactured by Tester Sangyo Co., Ltd., product name "TE-600") was used, with a probe diameter of φ5.05 mm, a pressing speed of 1.0 cm / s, a peeling speed of 1.0 cm / s, and a contact load of 1000 gf / cm. 2 The evaluation sample pieces were subjected to a probe tack test under measurement conditions of a contact time of 5.0 seconds, and the tack value of the cured coating film was measured.

[0110] (Measurement of elongation, strength and elastic modulus by tensile test) A tensile test was performed on the evaluation sample pieces at a temperature of 23°C and a humidity of 50%RH using a tensile tester (manufactured by Shimadzu Corporation, product name "AG-X") in accordance with JIS K 7127: 1999. The tensile speed was 10 mm / min, and the elongation (%) at the break point of the cured coating film, the elastic modulus (MPa) in the range of 1-2% displacement of the elongation deformation of the cured coating film, and the strength (MPa) at the break point of the cured coating film were measured. The elongation and elastic modulus of the cured coating film were measured and evaluated according to the following criteria. ◯: The elongation is 200% or more and the elastic modulus is less than 10 MPa. ×: The elongation is less than 200% and / or the elastic modulus is 10 MPa or more.

[0111] [Example 1] In a flask equipped with an internal thermometer, a stirrer and a cooling tube, 14.66 parts of a polyvalent isocyanate compound (a1-1), 80.99 parts of a polyol compound (a2-1-1), 1.06 parts of a polyol compound (a2-2-1), and 0.03 parts of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70 ° C. After the residual isocyanate group became 7.36% or less, 3.29 parts of a hydroxyl group-containing acrylate (a3-1) and 0.12 parts of 2,6-di-tert-butylcresol as a polymerization inhibitor were added and reacted at 70 ° C. The reaction was terminated when the residual isocyanate group became 0.1% or less, and a urethane acrylate compound was obtained. The weight average molecular weight of the resulting urethane acrylate compound was measured, and the results are shown in Table 1. In addition, evaluation sample pieces were prepared using the obtained urethane acrylate compound, and the glass transition temperature, tack value, elongation, strength and elastic modulus of the cured coating film were measured. The results are shown in Table 1.

[0112] [Examples 2 and 3, Comparative Examples 1 to 3] A urethane acrylate compound was obtained in the same manner as in Example 1, except that the types and amounts of raw materials used were changed as shown in Table 1. The weight average molecular weight of the resulting urethane acrylate compound was measured, and the results are shown in Table 1. In addition, evaluation sample pieces were prepared using the obtained urethane acrylate compound, and the glass transition temperature, tack value, elongation, strength and elastic modulus of the cured coating film were measured. The results are shown in Table 1.

[0113] [Table 1]

[0114] As is clear from the results in Table 1, the urethane acrylate compounds of Examples 1 to 3, which used a polyol compound (a2-1) having a melting point of 15°C or higher and a number average molecular weight of 500 or higher, were able to form cured coating films with an excellent balance between elongation and surface tackiness. On the other hand, the cured coating films formed from the urethane acrylate compounds of Comparative Examples 1 and 2, which used polyol compounds with melting points below 15° C., were not satisfactory in terms of both elongation and surface tackiness. The cured coating film formed from the urethane acrylate compound of Comparative Example 3, which used a polyol compound having a melting point of less than 15°C in combination with a polyol compound having a melting point of 15°C or higher and a molecular weight of 300 or less, was not satisfactory in terms of both elongation and surface tackiness. [Industrial Applicability]

[0115] INDUSTRIAL APPLICABILITY The urethane (meth)acrylate compound according to the present invention is useful as a raw material for active energy ray-curable resin compositions that can be used in various applications, such as coating agents, paints, inks, pressure sensitive adhesives, and bonding agents.

Claims

1. The copolymer has a structural unit derived from a polyisocyanate compound (a1), a structural unit derived from a polyol compound (a2-1), and a structural unit derived from a hydroxyl group-containing (meth)acrylate compound (a3), The polyol compound (a2-1) has a melting point of 15° C. or higher and a number average molecular weight of 500 or higher.

2. The urethane (meth)acrylate compound according to claim 1 , wherein the polyisocyanate compound (a1) is an alicyclic diisocyanate.

3. The urethane (meth)acrylate compound according to claim 1, further comprising a structural unit derived from a polyol compound (a2-2) having a molecular weight of 300 or less (excluding the polyol compound (a2-1)).

4. a cured coating film having a thickness of 100 μm formed using the urethane (meth)acrylate compound has an elongation of 200% or more at 23° C. in a tensile test; the tack value of the cured coating film at 23° C. in a probe tack test is 1.0 or less; The urethane (meth)acrylate compound according to claim 1 , wherein the cured coating film has a glass transition temperature of 0° C. or lower.

5. The urethane (meth)acrylate compound according to claim 1, wherein the weight average molecular weight of the urethane (meth)acrylate compound is 10,000 to 100,000.

6. An active energy ray-curable resin composition comprising the urethane (meth)acrylate compound according to any one of claims 1 to 5.

7. A coating agent comprising the active energy ray-curable resin composition according to claim 6.

8. A sheet comprising a cured product of the active energy ray-curable resin composition according to claim 6.

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