Electron beam-curable composition, and production method for electron beam-curable composition

Abstract

Provided are an electron beam-curable composition and a use therefor, the electron beam-curable composition including: a polymer (A) that includes a constituent unit derived from a (meth)acrylate having a (meth)acryloyl group; and a compound (B1) that has a trimethylolpropane structure and has two or more ethylenically unsaturated groups.

Description

Electron beam curable composition, and method for producing an electron beam curable composition

[0001] This disclosure relates to electron beam curable compositions and methods for producing electron beam curable compositions.

[0002] (Meth)acrylate polymers having (meth)acryloyl groups in their side chains, so-called (meth)acrylic (meth)acrylates, have the advantage of excellent weather resistance when used as coating agents, etc., because their main chain skeleton is composed of a (meth)acrylic structure.

[0003] On the other hand, active energy ray curable compositions are known as coating agents. Compared to thermosetting compositions, active energy ray curable compositions have advantages such as shorter curing time and lower energy requirements. In particular, electron beam curable compositions have advantages over ultraviolet curable compositions such as not requiring the inclusion of a photopolymerization initiator, allowing curing even with a high pigment content, and resulting in excellent weather resistance of the cured film.

[0004] For example, as an active energy ray curable composition, Patent Document 1 describes an active energy ray curable resin composition characterized by containing a reaction product (C) having a (meth)acrylic equivalent of 200 to 500 g / eq and a weight-average molecular weight of 50,000 to 200,000, and a saturated organic monocarboxylic acid component (D). Patent Document 2 describes an active energy ray curable composition containing 100 parts by mass of a (meth)acrylic block copolymer, which comprises a methacrylic polymer block (A) having an active energy ray curable group containing a specific substructure and a (meth)acrylic polymer block (B) not having an active energy ray curable group, wherein the content of the substructure relative to the total monomer units constituting the (meth)acrylic block copolymer is 0.3 mol% to 7.0 mol%, the content of the methacrylic polymer block (A) is 30% by mass to 60% by mass, and the number average molecular weight of the (meth)acrylic block copolymer is 13,000 or more, and 0.01 to 10 parts by mass of an active energy ray polymerization initiator.

[0005] On the other hand, as an electron beam curable composition, Patent Document 3 describes an electron beam curable paint containing colored particles, an acrylic poly(meth)acrylate containing 1.5 mol or more of (meth)acryloyl groups per 1,000 molecular weight, and a polyhydric alcohol (meth)acrylate containing two or more (meth)acryloyl groups in one molecule and having a (meth)acryloyl equivalent of 150 or less. Patent Document 4 describes an electron beam curable composition containing a polymerizable acrylic polymer containing an ultraviolet stability monomer unit and having a polymerizable double bond in a side chain.

[0006] JP 2011-57905 A, JP 2017-193644 A, JP 08-257498 A, JP 2000-109523 A

[0007] In the electron beam curable composition, there are cases where it is required that the obtained cured product has excellent mechanical properties and excellent solvent resistance.

[0008] The present disclosure has been made in view of such circumstances, and the problem to be solved by one embodiment of the present disclosure is to provide an electron beam curable composition capable of obtaining a cured product having excellent mechanical properties and excellent solvent resistance, and a method for producing an electron beam curable composition.

[0009] The present disclosure includes the following aspects. <1> An electron beam curable composition containing a polymer (A) containing a structural unit derived from a (meth)acrylate having a (meth)acryloyl group, and a compound (B1) having a trimethylolpropane structure and having two or more ethylenically unsaturated groups. <2> The electron beam curable composition according to <1>, wherein the structural unit derived from the (meth)acrylate having a (meth)acryloyl group is at least one selected from the group consisting of structural units represented by the following formulas (1A) to (1D). In Formulas (1A) to (1D), R １１ , R １２ , R ２１ , R ２２ , R ３１ , R ３２ , R ４１ , and R ４２ each independently represents a divalent organic group, and R １０ , R１３ , R ２０ , R ２３ , R ３０ , R ３３ , R ４０ , and R ４３Each independently represents a hydrogen atom or a methyl group. <3> The electron beam curable composition according to <1> or <2>, wherein polymer (A) has (meth)acryloyl groups in its side chains and has a (meth)acrylic equivalent of 500 to 5,000 g / eq. <4> The electron beam curable composition according to any one of <1> to <3>, wherein polymer (A) has a glass transition temperature of -15°C to 90°C. <5> The electron beam curable composition according to any one of <1> to <4>, wherein compound (B1) further has an alkylene oxide group. <6> The electron beam curable composition according to any one of <1> to <5>, further comprising compound (B2) having one ethylenically unsaturated group. <7> The electron beam curable composition according to any one of <1> to <6>, wherein the total content of polymer (A) and compound (B1) is 5% to 95% by mass based on the total amount of the electron beam curable composition. <8> The electron beam curable composition according to any one of <1> to <7>, wherein the content of polymer (A) is 20% to 90% by mass relative to the total content of polymer (A) and compound (B1). <9> The electron beam curable composition according to any one of <1> to <8>, used as a coating agent. <10> The electron beam curable composition according to any one of <1> to <8>, used as an outdoor coating agent. <11> A method for producing an electron beam curable composition, comprising the steps of: reacting a polymer (a1) containing a constituent unit derived from a (meth)acrylate (a1-1) that does not have a reactive group and a constituent unit derived from a (meth)acrylate (a1-2) that has a reactive group X with a (meth)acrylate (a2) that has a reactive group Y that can react with the reactive group X to produce a polymer (A) containing a constituent unit derived from a (meth)acrylate that has a (meth)acryloyl group; and mixing polymer (A) with a compound (B1) that has a trimethylolpropane structure and two or more ethylenically unsaturated groups. <12> The method for producing an electron beam curable composition according to <11>, wherein the reactive group X and the reactive group Y are an epoxy group, a carboxyl group, a hydroxyl group, or an isocyanate group.

[0010] According to one embodiment of the present disclosure, an electron beam curable composition is provided that can produce a cured product with excellent mechanical properties and excellent solvent resistance, and a method for producing the electron beam curable composition is provided.

[0011] In this specification, a numerical range indicated using "~" means a range that includes the numbers listed before and after "~" as the minimum and maximum values, respectively. In numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Furthermore, in numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples.

[0012] In this specification, the amount of each component in a composition means the total amount of multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" is included not only in the sense of an independent process, but also in the sense of a process that cannot be clearly distinguished from other processes, as long as the intended purpose of that process is achieved.

[0013] In this specification, "(meth)acrylate" means acrylate and / or methacrylate. Also, "(meth)acrylic" means acrylic and / or methacrylic. Furthermore, "(meth)acryloyl group" means acryloyl group and / or methacryloyl group.

[0014] [Electron beam curable composition] The electron beam curable composition of the present disclosure comprises a polymer (A) containing a constituent unit derived from a (meth)acrylate having a (meth)acryloyl group, and a compound (B1) having a trimethylolpropane structure and having two or more ethylenically unsaturated groups.

[0015] In the electron beam curable composition of this disclosure, a cured product with excellent mechanical properties and solvent resistance can be obtained by combining a polymer (A) containing constituent units derived from (meth)acrylate having a (meth)acryloyl group with a compound (B1) having a trimethylolpropane structure and two or more ethylenically unsaturated groups. The reason for obtaining such effects is not clear, but it is presumed that the following occurs: By using a compound (B1) having a trimethylolpropane structure and two or more ethylenically unsaturated groups, the reaction rate between the (meth)acryloyl group of polymer (A) and compound (B1) is improved. As a result, a cured product with excellent mechanical properties and solvent resistance can be obtained.

[0016] The electron beam curable composition of this disclosure is a composition that is cured by irradiation with an electron beam.

[0017] Electron beam irradiation can be performed using an electron beam irradiation device. The electron beam irradiation conditions are not particularly limited. The acceleration voltage for electron beam irradiation is, for example, 80 kV to 250 kV, preferably 100 kV to 200 kV. The dose for electron beam irradiation is, for example, 1 kGy to 1000 kGy, preferably 10 kGy to 500 kGy.

[0018] <Polymer (A)> The electron beam curable composition of this disclosure comprises polymer (A) (hereinafter also simply referred to as "polymer (A)") which includes constituent units derived from (meth)acrylate having a (meth)acryloyl group. In this disclosure, "polymer" refers to a polymer with a weight-average molecular weight of 2,000 or more.

[0019] A (meth)acrylate having a (meth)acryloyl group is acceptable as long as it has a (meth)acryloyl group, and from the viewpoint of ease of synthesis and the mechanical properties of the resulting cured product, it is preferable that it contains a urethane bond (-NH-C(=O)O-) or an ester bond (-C(=O)O-). Furthermore, from the viewpoint of electron beam curability, it is preferable that the (meth)acrylate having a (meth)acryloyl group is a (meth)acrylate having an acryloyl group.

[0020] In particular, the constituent unit derived from (meth)acrylate having a (meth)acryloyl group is preferably at least one selected from the group consisting of constituent units represented by the following formulas (1A) to (1D).

[0021] In formulas (1A) to (1D), R １１ , R １２ , R ２１ , R ２２ , R ３１ , R ３２ , R ４１ , and R ４２ Each of these independently represents a divalent organic group, R １０ , R １３ , R ２０ , R ２３ , R ３０ , R ３３ , R ４０ , and R ４３ Each of these independently represents either a hydrogen atom or a methyl group.

[0022] A divalent organic group may have at least one heteroatom selected from the group consisting of oxygen and nitrogen atoms. For example, a divalent organic group may include ether bonds, ester bonds, amide bonds, urethane bonds, and the like.

[0023] (Formula (1A)) A polymer (A) containing the constituent units represented by formula (1A) can be produced, for example, by reacting a polymer containing constituent units derived from a (meth)acrylate having a hydroxyl group with a (meth)acrylate having an isocyanate group.

[0024] Examples of (meth)acrylates having a hydroxyl group include hydroxyalkyl (meth)acrylates.

[0025] Examples of hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0026] The (meth)acrylate having a hydroxyl group may be an ε-caprolactone adduct of a hydroxyalkyl (meth)acrylate such as an ε-caprolactone adduct of 2-hydroxyethyl (meth)acrylate, a polypropylene glycol adduct of (meth)acrylic acid, a polyethylene glycol adduct of (meth)acrylic acid, a poly(3-hydroxybutyrate) adduct of 2-hydroxyethyl (meth)acrylate, or a polytetramethylene glycol adduct of (meth)acrylic acid.

[0027] ε-caprolactone adducts of 2-hydroxyethyl (meth)acrylate may be commercially available. Examples of commercially available products include Praxel FA2D (ε-caprolactone adduct of 2-hydroxyethyl acrylate), Praxel FA5 (ε-caprolactone adduct of 2-hydroxyethyl acrylate, molecular weight 689), Praxel FM2D (ε-caprolactone adduct of 2-hydroxyethyl methacrylate), Praxel FM3 (ε-caprolactone adduct of 2-hydroxyethyl methacrylate), and Praxel FM5 (ε-caprolactone adduct of 2-hydroxyethyl methacrylate), all manufactured by Daicel Corporation.

[0028] Examples of (meth)acrylates having an isocyanate group include (meth)acryloyloxyethyl isocyanate. (Meth)acryloyloxyethyl isocyanate may be a commercially available product. Examples of commercially available products include Karenz MOI and Karenz AOI manufactured by Showa Denko Corporation.

[0029] Furthermore, polymer (A) containing the constituent units represented by formula (1A) can be produced, for example, by reacting a polymer containing constituent units derived from a (meth)acrylate having a hydroxyl group with a diisocyanate, and then reacting it with a (meth)acrylate having a hydroxyl group.

[0030] Specific examples of (meth)acrylates having a hydroxyl group are as described above.

[0031] Examples of diisocyanates include aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; alicyclic diisocyanates such as hydrogenated tolylene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate; and aromatic diisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, paraphenylenedi diisocyanate, and 1,5-naphthalene diisocyanate.

[0032] In formula (1A), R １１ Examples of divalent organic groups in include divalent hydrocarbon groups. Divalent hydrocarbon groups may have an oxygen atom at the carbonyl end. In formula (1A), R １２ Examples of divalent organic groups in this context include divalent hydrocarbon groups. Divalent hydrocarbon groups may contain urethane bonds, ester bonds, or amide bonds between carbon atoms.

[0033] Examples of divalent hydrocarbon groups include alkylene groups, aromatic hydrocarbon groups, and groups consisting of combinations thereof.

[0034] In formula (1A), R １１ It is preferable that the group is an alkylene oxide group. However, the oxygen atom of the alkylene oxide group is bonded to the carbon atom of the carbonyl group in formula (1A). The alkylene oxide group has 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

[0035] In formula (1A), R １２ It is preferably an alkylene group. The alkylene group has 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms. Also, R １２ *1-R ｋ１ -OC(=O)NH-R ｋ２ -*2 is also preferable. R ｋ１ and R ｋ２Each of these is an alkylene group, where *1 is bonded to an oxygen atom and *2 is bonded to a nitrogen atom. ｋ１ The number of carbon atoms in the alkylene group represented by is preferably 1 to 6, and more preferably 1 to 4. ｋ２ The number of carbon atoms in the alkylene group represented by is preferably 1 to 10, and more preferably 2 to 8.

[0036] In formula (1A), R １３ This is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.

[0037] (Formula (1B)) A polymer (A) containing the constituent units represented by formula (1B) can be produced, for example, by reacting a polymer containing constituent units derived from a (meth)acrylate having an isocyanate group with a (meth)acrylate having a hydroxyl group.

[0038] Specific examples of (meth)acrylates having an isocyanate group and (meth)acrylates having a hydroxyl group are as described above.

[0039] Furthermore, polymer (A) containing the constituent units represented by formula (1B) can be produced, for example, by reacting a polymer containing constituent units derived from a (meth)acrylate having an isocyanate group with a diol, and then reacting it with a (meth)acrylate having an isocyanate group.

[0040] Specific examples of (meth)acrylates having an isocyanate group are as described above.

[0041] Examples of diols include ethylene glycol, propylene glycol, cyclohexanedimethanol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol.

[0042] In formula (1B), R ２１ Examples of divalent organic groups in this context include divalent hydrocarbon groups. Divalent hydrocarbon groups may contain urethane bonds, ester bonds, or amide bonds between carbon atoms.

[0043] In formula (1B), R２２ Examples of divalent organic groups include divalent hydrocarbon groups. Divalent hydrocarbon groups may contain urethane bonds, ester bonds, or amide bonds between carbon atoms. Divalent hydrocarbon groups may have an oxygen atom at the carbonyl end.

[0044] Examples of divalent hydrocarbon groups include alkylene groups, aromatic hydrocarbon groups, and groups consisting of combinations thereof.

[0045] In formula (1B), R ２１ It is preferable that the group is an alkylene group. The alkylene group has 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

[0046] In formula (1B), R ２２ It is preferably an alkylene oxide group. However, the oxygen atom of the alkylene oxide group is bonded to the carbon atom of the carbonyl group in formula (1B). The number of carbon atoms in the alkylene oxide group is preferably 1 to 6, and more preferably 1 to 4. Also, R ２２ *1-R ｋ３ -NH-C(=O)OR ｋ４ It is also preferable that it be -O-*2. ｋ３ and R ｋ４ Each of these is an alkylene group, where *1 is bonded to an oxygen atom and *2 is bonded to a carbon atom of a carbonyl group. ｋ３ The number of carbon atoms in the alkylene group represented by is preferably 1 to 6, and more preferably 1 to 4. ｋ４ The number of carbon atoms in the alkylene group represented by is preferably 1 to 10, and more preferably 2 to 8.

[0047] In formula (1B), R ２３ This is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.

[0048] (Formula (1C)) A polymer (A) containing the constituent units represented by formula (1C) can be produced, for example, by reacting a polymer containing constituent units derived from an epoxy group-containing (meth)acrylate with a carboxyl group-containing (meth)acrylate.

[0049] Examples of (meth)acrylates having an epoxy group include glycidyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether.

[0050] Examples of (meth)acrylates having a carboxyl group include monohydroxyethyl acrylate phthalate, ω-carboxy-polycaprolactone monoacrylate, (meth)acryloyloxyethyl succinate, (meth)acryloyloxyethyl hexahydrophthalate, (meth)acryloyloxyethyl phthalate, (meth)acryloyloxyethyl-2-hydroxyethyl phthalate, β-carboxyethyl acrylate, phthalic anhydride adduct of pentaerythritol triacrylate, succinic anhydride adduct of pentaerythritol triacrylate, succinic anhydride adduct of dipentaerythritol triacrylate, and phthalic anhydride adduct of dipentaerythritol triacrylate.

[0051] Furthermore, polymer (A) containing the constituent units represented by formula (1C) can be produced, for example, by reacting a polymer containing constituent units derived from (meth)acrylate having epoxy groups with a dicarboxylic acid, and then reacting it with (meth)acrylate having epoxy groups.

[0052] Specific examples of (meth)acrylates having epoxy groups are as described above.

[0053] Examples of dicarboxylic acids include adipic acid, azelaic acid, sebatic acid, undecanediic acid, dodecanediic acid, dimer acid, isophthalic acid, and terephthalic acid.

[0054] In formula (1C), R ３１ Examples of divalent organic groups in this formula include divalent hydrocarbon groups. In formula (1C), R ３２ Examples of divalent organic groups in this context include divalent hydrocarbon groups. Divalent hydrocarbon groups may contain urethane bonds, ester bonds, or amide bonds between carbon atoms.

[0055] Examples of divalent hydrocarbon groups include alkylene groups, aromatic hydrocarbon groups, and groups consisting of combinations thereof.

[0056] In formula (1C), R ３１ It is preferable that the group is an alkylene group. The alkylene group has 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

[0057] In formula (1C), R ３２ The alkylene group is preferably an alkylene group. The alkylene group may contain an ester bond. The alkylene group has 1 to 20 carbon atoms, and more preferably 6 to 15 carbon atoms.

[0058] In formula (1C), R ３３ This is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.

[0059] (Formula (1D)) A polymer (A) containing the constituent units represented by formula (1D) can be produced, for example, by reacting a polymer containing constituent units derived from a (meth)acrylate having a carboxyl group with a (meth)acrylate having an epoxy group.

[0060] Specific examples of (meth)acrylates having a carboxyl group and (meth)acrylates having an epoxy group are as described above.

[0061] Furthermore, polymer (A) containing the constituent units represented by formula (1D) can be produced, for example, by reacting a polymer containing constituent units derived from a (meth)acrylate having a carboxyl group with a compound having two epoxy groups, and then reacting it with a (meth)acrylate having a carboxyl group.

[0062] Specific examples of (meth)acrylates having a carboxyl group are as described above.

[0063] Examples of compounds having two epoxy groups include diglycidyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A diglycidyl ether, and bisphenol F diglycidyl ether.

[0064] In formula (1D), R ４１ Examples of divalent organic groups in this include divalent hydrocarbon groups. In formula (1D), R ４２ Examples of divalent organic groups in this context include divalent hydrocarbon groups. Divalent hydrocarbon groups may contain urethane bonds, ester bonds, or amide bonds between carbon atoms.

[0065] Examples of divalent hydrocarbon groups include alkylene groups, aromatic hydrocarbon groups, and groups consisting of combinations thereof.

[0066] In formula (1D), R ４１ The alkylene group is preferably an alkylene group. The alkylene group may contain an ester bond. The alkylene group has 1 to 20 carbon atoms, and more preferably 6 to 15 carbon atoms.

[0067] In formula (1D), R ４２ The alkylene group is preferably an alkylene group. The alkylene group may contain an ester bond. The alkylene group preferably has 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

[0068] In formula (1D), R ４３ This is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.

[0069] The polymer (A) preferably contains other constituent units other than those derived from (meth)acrylate having a (meth)acryloyl group.

[0070] From the viewpoint of ease of manufacture, the other constituent units are preferably constituent units derived from polymerizable compounds that do not have reactive groups.

[0071] In particular, from the viewpoint of weather resistance, transparency, and smoothness of the cured product, the polymerizable compound without reactive groups is preferably at least one selected from the group consisting of monofunctional (meth)acrylates and styrene compounds without reactive groups, and more preferably a monofunctional (meth)acrylate and styrene compound without reactive groups.

[0072] Examples of monofunctional (meth)acrylates that do not have reactive groups include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, C12-C13 alkyl (meth)acrylate, and cetyl (meth)acrylate. Examples include monofunctional (meth)acrylates having aliphatic hydrocarbon groups such as stearyl (meth)acrylate, isostearyl (meth)acrylate, or isomiristyl (meth)acrylate; and monofunctional (meth)acrylates having alicyclic hydrocarbon groups such as bornyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, cyclic trimethylolpropaneformal (meth)acrylate, dicyclopentenyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecane (meth)acrylate, or dicyclopentenyloxyethyl (meth)acrylate.

[0073] Examples of styrene compounds include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, and p-methoxy-β-methylstyrene.

[0074] The polymer (A) preferably has (meth)acryloyl groups in its side chains and a (meth)acrylic equivalent of 500 to 5,000 g / eq.

[0075] If the (meth)acrylic equivalent of polymer (A) is 500 g / eq or more, the cured product exhibits excellent toughness. If the (meth)acrylic equivalent of polymer (A) is 5,000 g / eq or less, the cured product exhibits excellent hardness.

[0076] From the above viewpoint, the (meth)acrylic equivalent of polymer (A) is more preferably 600 g / eq to 4,000 g / eq, and even more preferably 700 g / eq to 3,000 g / eq.

[0077] In this disclosure, (meth)acrylic equivalent represents the mass (g) per equivalent (eq) of (meth)acryloyl groups. A higher value indicates a lower (meth)acryloyl group content. Conversely, a lower value indicates a higher (meth)acryloyl group content.

[0078] The (meth)acrylic equivalent can be calculated using the following formula.

[0079] (meth)acrylic equivalent (g / eq) = [mass of polymer (A) (g)] / [number of moles of (meth)acryloyl groups contained in polymer (A)]

[0080] The number of moles of (meth)acryloyl groups contained in polymer (A) of the above formula is calculated by the following method: A predetermined amount of isopropyl acetate is added to polymer (A) as an internal standard. １ Based on the peak integral values ​​derived from (meth)acryloyl groups and isopropyl acetate obtained from 1H-NMR measurements, the number of moles of (meth)acryloyl groups contained in polymer (A) is calculated.

[0081] The polymer (A) preferably has a glass transition temperature of -15°C to 90°C.

[0082] If polymer (A) has a glass transition temperature of -15°C or higher, the cured product exhibits excellent strength. If polymer (A) has a glass transition temperature of 90°C or lower, the cured product exhibits excellent flexibility.

[0083] From the above viewpoint, the glass transition temperature of polymer (A) is more preferably -10°C to 85°C, and even more preferably 0°C to 80°C.

[0084] In this disclosure, the glass transition temperature refers to the temperature determined from the intersection of the baseline and the tangent at the inflection point of the heat flux curve obtained using a differential scanning calorimeter. An example of a differential scanning calorimeter is the Q-100 manufactured by TA Instrument. The heat flux curve is obtained by cooling approximately 10 mg of a sample to -100°C in a nitrogen atmosphere, holding for 5 minutes, then raising the temperature to 120°C at 10°C / min, continuing to cool to -100°C, holding for 5 minutes, and then raising the temperature to 350°C at 10°C / min.

[0085] The weight-average molecular weight (Mw) of polymer (A) is preferably 5,000 to 200,000. When the Mw of polymer (A) is 5,000 or more, it exhibits excellent weather resistance and mechanical properties. When the Mw of polymer (A) is 200,000 or less, it exhibits excellent coating properties and excellent compatibility when mixed with other compounds having ethylenically unsaturated groups. From the above viewpoint, the Mw of polymer (A) is more preferably 5,000 to 150,000, and even more preferably 8,000 to 100,000.

[0086] In this disclosure, Mw means the value of the molecular weight measured by gel permeation chromatography (hereinafter referred to as GPC) converted to polystyrene equivalent.

[0087] The content of polymer (A) is preferably 20% to 90% by mass relative to the total content of polymer (A) and compound (B1) described later. When the content of polymer (A) is 20% by mass or more relative to the total content, the coating properties are excellent. When the content of polymer (A) is 90% by mass or less relative to the total content, the reactivity properties are excellent.

[0088] From the above viewpoint, the content of polymer (A) is more preferably 20% to 80% by mass, and even more preferably 30% to 70% by mass, relative to the total content.

[0089] The content of polymer (A) is preferably 20% to 90% by mass relative to the total amount of the electron beam curable composition.

[0090] <Compound (B1)> The electron beam curable composition of this disclosure comprises compound (B1) having a trimethylolpropane structure and two or more ethylenically unsaturated groups (hereinafter also simply referred to as "compound (B1)").

[0091] Examples of ethylenically unsaturated groups contained in compound (B1) include (meth)acryloyl groups, maleimide groups, (meth)acrylamide groups, and vinyl groups.

[0092] From the viewpoint of curability, the ethylenically unsaturated group contained in compound (B1) is preferably a (meth)acryloyl group.

[0093] The compound (B1) contains two or more ethylenically unsaturated groups, preferably two to eight, and more preferably three or four.

[0094] Examples of compound (B1) include trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri or tetra(meth)acrylate, trimethylolpropane alkylene oxide adduct tri(meth)acrylate, and ditrimethylolpropane alkylene oxide adduct tri or tetra(meth)acrylate.

[0095] In particular, compound (B1) preferably further has an alkylene oxide group. The alkylene oxide group is preferably at least one selected from the group consisting of an ethylene oxide group and a propylene oxide group, and more preferably a propylene oxide group.

[0096] The number of alkylene oxide groups in compound (B1) is preferably 1 to 20, and more preferably 3 to 15.

[0097] When compound (B1) contains an alkylene oxide group, the resulting cured product exhibits excellent elongation and improved mechanical properties.

[0098] From the above viewpoint, compound (B1) is preferably a tri(meth)acrylate of a trimethylolpropanealkylene oxide adduct, or a tri or tetra(meth)acrylate of a ditrimethylolpropanealkylene oxide adduct, more preferably a tri(meth)acrylate of a trimethylolpropanealkylene oxide adduct, and even more preferably a tri(meth)acrylate of a trimethylolpropanepropylene oxide adduct.

[0099] The total content of polymer (A) and compound (B1) is preferably 5% by mass or more, more preferably 5% to 95% by mass, and even more preferably 10% to 90% by mass, based on the total amount of the electron beam curable composition.

[0100] The content of compound (B1) is preferably 10% to 80% by mass relative to the total amount of the electron beam curable composition.

[0101] <Compound (B2)> The electron beam curable composition of this disclosure may contain components other than polymer (A) and compound (B1). In particular, the electron beam curable composition of this disclosure preferably further contains compound (B2) having one ethylenically unsaturated group (hereinafter also simply referred to as "compound (B2)").

[0102] When compound (B2) is included in addition to polymer (A) and compound (B1), the resulting cured product exhibits superior elongation and improved mechanical properties.

[0103] Examples of ethylenically unsaturated groups contained in compound (B2) include (meth)acryloyl groups, maleimide groups, (meth)acrylamide groups, and vinyl groups.

[0104] From the viewpoint of curability, the ethylenically unsaturated group contained in compound (B2) is preferably a (meth)acryloyl group. That is, compound (B2) is preferably a monofunctional (meth)acrylate.

[0105] The monofunctional (meth)acrylate may be a monofunctional (meth)acrylate that does not have the above-mentioned reactive group, or it may be a monofunctional (meth)acrylate that has the reactive group.

[0106] Specific examples of monofunctional (meth)acrylates that do not have reactive groups are as described above.

[0107] Examples of monofunctional (meth)acrylates having reactive groups include (meth)acrylates having a hydroxyl group, (meth)acrylates having an isocyanate group, (meth)acrylates having an epoxy group, and (meth)acrylates having a carboxyl group.

[0108] In particular, compound (B2) preferably further has an alkylene oxide group. The alkylene oxide group is preferably at least one selected from the group consisting of ethylene oxide group and propylene oxide group, and more preferably an ethylene oxide group.

[0109] The number of alkylene oxide groups in compound (B2) is preferably 1 to 20, and more preferably 1 to 6.

[0110] When compound (B2) contains an alkylene oxide group, the resulting cured product exhibits excellent elongation and improved mechanical properties.

[0111] From the above viewpoint, it is preferable that compound (B2) is a (meth)acrylate of an alkylene oxide adduct of an aromatic compound, such as a (meth)acrylate of an alkylene oxide adduct of a phenol, a (meth)acrylate of an alkylene oxide adduct of an alkylphenol, a (meth)acrylate of an alkylene oxide adduct of p-cumylphenol, or a (meth)acrylate of an alkylene oxide adduct of o-phenylphenol; and an alkyl carbitol (meth)acrylate, such as ethyl carbitol (meth)acrylate, butyl carbitol (meth)acrylate, or 2-ethylhexyl carbitol (meth)acrylate.

[0112] When the electron beam curable composition contains compound (B2), the content of compound (B2) is preferably 5% to 30% by mass relative to the total amount of the electron beam curable composition.

[0113] When the electron beam curable composition contains compound (B2), the mass ratio of the content of compound (B2) to the content of compound (B1) is preferably 0.2 to 5.

[0114] <Other Components> The electron beam curable composition of this disclosure may contain other components besides the compound (B2) described above.

[0115] Other ingredients can be selected as appropriate depending on the purpose.

[0116] When the electron beam curable composition of this disclosure is used as a coating agent, other components may include, for example, polymerization inhibitors, antioxidants, lightfastness enhancers, inorganic particles, surface modifiers, pigments, dyes, tackifiers, and the like.

[0117] Examples of polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, and 2,6-di-tert-butyl-4-methylphenol.

[0118] As antioxidants, phenolic antioxidants are preferred, but sulfur-based secondary antioxidants, phosphorus-based secondary antioxidants, and the like are also acceptable.

[0119] The lightfastness enhancer may be an ultraviolet absorber or a light stabilizer.

[0120] Examples of UV absorbers include benzotriazole compounds such as 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, and 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)benzotriazole; and triazine compounds such as 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-isooctyloxyphenyl)-s-triazine; Examples include benzophenone compounds such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3',4,4'-tetrahydroxybenzophenone, or 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0121] Examples of light stabilizers include hindered amine compounds such as N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-N,N'-diformylhexamethylenediamine, bis(1,2,2,6,6-)pentamethyl-4-piperidyl)-2-(3,5-diter-butyl-4-hydroxybenzyl)-2-n-butylmalonate, and bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate.

[0122] [Applications] The electron beam curable compositions of this disclosure are applicable to a variety of uses. For example, the electron beam curable compositions of this disclosure can be used as coatings, adhesives, inks, or films, and are preferably used as coatings, and more preferably as outdoor coatings.

[0123] Specific applications of coating agents include various paints, decorative films, and topcoats.

[0124] More specific applications of the coating agent include hard coating applications. Suitable substrates include plastic films used in polarizer protective films and anti-reflective films, as well as resin molded products used in home appliances and automotive interior and exterior parts.

[0125] Other applications of the coating agent include its suitability as a coating agent for metal substrates, and it can be used as an electrode protective coating agent for PDPs (plasma display panels), circuit board protective materials for electric bicycles, and lithium-ion batteries, as well as a coating agent for automotive interior and exterior components. The electron beam curable composition of this disclosure is suitable for use as an outdoor coating agent for outdoor applications such as building exteriors, outdoor signs, and automotive exteriors, because the resulting cured product has excellent mechanical properties and excellent solvent resistance.

[0126] [Method for Producing an Electron Beam Curable Composition] The method for producing an electron beam curable composition according to the present disclosure includes a step of reacting a polymer (a1) containing a constituent unit derived from a (meth)acrylate (a1-1) that does not have a reactive group and a constituent unit derived from a (meth)acrylate (a1-2) that has a reactive group X with a (meth)acrylate (a2) that has a reactive group Y that can react with the reactive group X to produce a polymer (A) containing a constituent unit derived from a (meth)acrylate that has a (meth)acryloyl group (hereinafter also referred to as the "polymer (A) production step") and a step of mixing polymer (A) with a compound (B1) that has a trimethylolpropane structure and two or more ethylenically unsaturated groups (hereinafter also referred to as the "mixing step").

[0127] <Polymer (A) Manufacturing Process> The polymer (A) manufacturing process is a process of reacting polymer (a1), which contains a constituent unit derived from (meth)acrylate (a1-1) that does not have a reactive group, and a constituent unit derived from (meth)acrylate (a1-2) that has a reactive group X, with (meth)acrylate (a2) that has a reactive group Y that can react with the reactive group X, to produce polymer (A) which contains a constituent unit derived from (meth)acrylate that has a (meth)acryloyl group.

[0128] (Polymer (a1)) Polymer (a1) includes constituent units derived from (meth)acrylate (a1-1) without reactive groups, and constituent units derived from (meth)acrylate (a1-2) having reactive group X. Specific examples of (meth)acrylate without reactive groups are as described above. Specific examples of (meth)acrylate having reactive groups are as described above.

[0129] Polymer (a1) is produced, for example, by known polymerization methods such as suspension polymerization, emulsion polymerization, solution polymerization, and bulk polymerization, using (meth)acrylate without reactive groups and (meth)acrylate having reactive groups X as raw materials.

[0130] Bulk polymerization or solution polymerization is preferred as the polymerization method because it is easy to manufacture the polymer and does not contain impurities such as emulsifiers.

[0131] In solution polymerization, for example, the raw materials are dissolved in an organic solvent, a thermal polymerization initiator is added, and the mixture is heated and stirred. A chain transfer agent may be used if necessary.

[0132] Examples of organic solvents include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate; ethers such as propylene glycol monomethyl ether; aromatic hydrocarbons such as toluene and xylene; and aliphatic hydrocarbons such as hexane, heptane, and mineral spirits.

[0133] Examples of thermal polymerization initiators include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), azobiscyclohexacarbonnitrile, azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-amidinopropane)dihydrochloride, and 4,4'-azobis(4-cyanovaleric acid); and organic peroxides such as di-t-butyl peroxide, di-t-hexyl peroxide, t-hexyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, cumene hydroperoxide, and t-butyl hydroperoxide.

[0134] ((meth)acrylate(a2)) (meth)acrylate(a2) has a reactive group Y that can react with the reactive group X contained in polymer(a1).

[0135] The reaction between reactive group X and reactive group Y yields polymer (A) containing constituent units derived from (meth)acrylate having a (meth)acryloyl group.

[0136] In the reaction between polymer (a1) and (meth)acrylate (a2), the mixing ratio of polymer (a1) and (meth)acrylate (a2) is preferably 0.5 to 1.5 moles, more preferably 0.8 to 1.2 moles, and even more preferably 0.9 to 1.1 moles, of reactive groups Y of (meth)acrylate (a2) per mole of reactive groups X of polymer (a1).

[0137] From the viewpoint of reactivity, reactive groups X and Y are preferably epoxy groups, carboxyl groups, hydroxyl groups, or isocyanate groups.

[0138] The following combinations of reactive group X and reactive group Y are preferred: 1. Reactive group X is a hydroxyl group and reactive group Y is an isocyanate group. 2. Reactive group X is an isocyanate group and reactive group Y is a hydroxyl group. 3. Reactive group X is an epoxy group and reactive group Y is a carboxyl group. 4. Reactive group X is a carboxyl group and reactive group Y is an epoxy group. 5. Reactive group X is a hydroxyl group and reactive group Y is a carboxyl group. 6. Reactive group X is a carboxyl group and reactive group Y is a hydroxyl group.

[0139] In particular, from the viewpoint of ease of synthesis and storage stability of polymer (a1), the combination of reactive group X and reactive group Y is preferred in embodiment 1 or embodiment 3, with embodiment 1 being more preferred.

[0140] In embodiment 1 or embodiment 2, for example, polymer (A) is obtained by mixing polymer (a1) and (meth)acrylate (a2), then adding a curing catalyst such as dibutyltin dilaurate as needed, and heating to 60°C to 100°C.

[0141] In embodiment 3 or embodiment 4, for example, polymer (A) is obtained by heating a mixture of polymer (a1), (meth)acrylate (a2), catalyst, and organic solvent to 60°C to 120°C for about 5 to 30 hours.

[0142] Examples of catalysts include tetrabutylammonium bromide, tetrabutylammonium chloride, tetramethylammonium bromide, tetramethylammonium chloride, triphenylphosphine, tributylphosphine, 1,8-diazabicyclo[5,4,0]-7-undecene, and 1,4-diazabicyclo[2,2,2]octane.

[0143] Examples of organic solvents include ethyl acetate, butyl acetate, acetone, and methyl ethyl ketone.

[0144] In embodiment 5 or embodiment 6, for example, polymer (A) is obtained by heating a mixture of polymer (a1), (meth)acrylate (a2), catalyst, and organic solvent to 100°C to 120°C, and then azeotropically dehydrating the organic solvent and the resulting water.

[0145] Examples of catalysts include p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, and sulfuric acid.

[0146] As the organic solvent, it is preferable to use an organic solvent that has low solubility with water produced in the dehydration esterification reaction and that allows the reaction to proceed while water is removed by azeotrope. Examples of organic solvents include aromatic hydrocarbons such as toluene, benzene, and xylene; aliphatic hydrocarbons such as hexane, cyclohexane, and heptane; and ketones such as methyl ethyl ketone and cyclohexanone.

[0147] After the reaction, the acid is generally removed with water or an alkaline aqueous solution.

[0148] In all of embodiments 1 to 6, it is preferable to add a polymerization inhibitor for the purpose of suppressing gelation or for the purpose of improving the storage stability of polymer (A).

[0149] Examples of polymerization inhibitors include methoxyphenol, hydroquinone, and dibutylhydroxytoluene. From the viewpoint of suppressing discoloration of the cured product, dibutylhydroxytoluene is preferred as the polymerization inhibitor.

[0150] <Mixing Step> In the mixing step, polymer (A) and compound (B1) are mixed. The mixing method is not particularly limited. After mixing, stirring may be performed.

[0151] The present disclosure will be explained in more detail below with reference to examples and comparative examples, but this disclosure is not limited thereto.

[0152] The weight-average molecular weight (Mw), number-average molecular weight (Mn), glass transition temperature, and (meth)acrylic equivalent were measured according to the following method.

[0153] (Weight-average molecular weight (Mw), number-average molecular weight (Mn)) The obtained polymers were subjected to gel permeation chromatography (GPC) under the conditions described below to obtain the number-average molecular weight (Mn) and weight-average molecular weight (Mw) in polystyrene equivalent. -Measurement conditions- Column: 4 x TSKgel SuperMultiporeHZ-M columns manufactured by Tosoh Solvent: Tetrahydrofuran Temperature: 40°C Detector: RI Flow rate: 600 μL / min

[0154] ((meth)acrylic equivalent (g / eq)) A predetermined amount of isopropyl acetate was added to polymer (A) as an internal standard substance. １ Based on the peak integral values ​​derived from (meth)acryloyl groups and isopropyl acetate obtained from 1H-NMR measurements, the number of moles of (meth)acryloyl groups contained in polymer (A) was calculated.

[0155] (Glass transition temperature) The glass transition temperature was determined from the intersection of the baseline and the tangent at the inflection point of the heat flux curve obtained using a differential scanning calorimeter. A Q-100 manufactured by TA Instrument was used as the differential scanning calorimeter. The heat flux curve was obtained under the following conditions: approximately 10 mg of the sample was cooled to -100°C in a nitrogen atmosphere, held for 5 minutes, then heated to 120°C at 10°C / min, subsequently cooled to -100°C, held for 5 minutes, and then heated to 350°C at 10°C / min.

[0156] The methods for producing polymers A1 to A9, which are polymers (A), and polymer AA1, which is another polymer, are as follows. First, polymers a1-1 to a1-9 were produced as polymers (a1). Then, polymers A1 to A9 and polymer AA1 were produced by reacting polymers (a1) with (meth)acrylate (a2).

[0157] <Production of Polymer A1> In a glass reactor equipped with a stirrer, reflux condenser, thermometer, nitrogen inlet pipe, and liquid supply piping connection, 20 parts by mass of butyl acetate, 10 parts by mass of methyl methacrylate (hereinafter referred to as "MMA"), 10 parts by mass of isobutyl methacrylate (hereinafter referred to as "IBMA"), 5 parts by mass of butyl acrylate (hereinafter referred to as "BA"), 7.5 parts by mass of 2-ethylhexyl methacrylate (hereinafter referred to as "HMA"), 7.5 parts by mass of styrene (hereinafter referred to as "St"), 10 parts by mass of 2-hydroxyethyl methacrylate (hereinafter referred to as "HEMA"), and 0.5 parts by mass of the chain transfer agent 2-ethylhexyl thioglycolate (hereinafter referred to as "OTG"). The internal temperature of the reactor was adjusted to 90°C while stirring and blowing in nitrogen gas. Meanwhile, 10 parts by mass of MMA, 10 parts by mass of IBMA, 5 parts by mass of BA, 7.5 parts by mass of HMA, 7.5 parts by mass of St, 10 parts by mass of HEMA, and 0.5 parts by mass of OTG were charged into a glass container fitted with a liquid delivery pipe using a metering pump, and stirred to prepare a monomer mixture (50.5 parts by mass). In addition, 0.7 parts by mass of the polymerization initiator 2,2'-azobis(2-methylbutyronitrile) (hereinafter referred to as "ABN-E") and 35 parts by mass of butyl acetate were charged into another glass container fitted with a liquid delivery pipe using a separate metering pump. After confirming that the internal temperature of the reactor had stabilized at 90°C, a polymerization initiator solution prepared by dissolving 0.07 parts by mass of the polymerization initiator ABN-E in 3.5 parts by mass of butyl acetate was added to the reactor. Next, five minutes later, the monomer mixture and initiator solution were supplied to the reactor using a metering pump. The monomer mixture was supplied to the reactor at a constant rate for 180 minutes, and the initiator solution for 330 minutes. Thirty minutes later, 0.23 parts by mass of ABN-E and 11.5 parts by mass of butyl acetate were added to the initiator solution, and the internal temperature was maintained for four hours. This yielded a solution containing polymer a1-1 having constituent units derived from MMA, IBMA, BA, HMA, St, and HEMA.

[0158] Next, the solution containing polymer a1-1 in the reactor (172 parts by mass, 102 parts by mass of solids) was cooled to 80°C over 30 minutes. Then, the nitrogen gas injection was changed to air injection, and 0.005 parts by mass of dibutylhydroxytoluene (hereinafter referred to as "BHT") was immediately added. Five minutes after the addition of BHT, 10.77 parts by mass of 2-acryloyloxyethyl isocyanate (hereinafter referred to as "AOI") was supplied to the reactor. Five minutes later, 0.02 parts by mass of dibutyltin dilaurate (product name "Neostan U-810", manufactured by Nitto Chemical Co., Ltd., "DBTL" in Table 1) was supplied to the reactor at a constant rate over 30 minutes, and the reactor was heated at an internal temperature of 80°C for 2 hours. The hydroxyl groups contained in polymer a1-1 reacted with the isocyanate groups contained in AOI to obtain a solution of polymer A1 containing constituent units derived from methacrylate having acryloyl groups.

[0159] <Production of Polymers A2 to A8> Polymers A2 to A8 were obtained in the same manner as in the production of Polymer A1, except that the types and contents of each component used in the production of the polymers were changed as shown in Table 1.

[0160] <Preparation of Polymer A9> Polymer a1-9 was obtained in the same manner as the preparation of Polymer a1-1, except that the types and contents of each component used in the preparation of the polymer were changed as shown in Table 1. In Table 1, "GMA" means glycidyl methacrylate. Next, a solution of Polymer a1-9 (172 parts by mass, 102 parts by mass of solids), 0.193 parts by mass of BHT, 21.13 parts by mass of ω-carboxy-polycaprolactone monoacrylate (product name "Aronics M-5300", hereinafter referred to as "M-5300"), and 0.97 parts by mass of tetrabutylammonium bromide (hereinafter referred to as "TBAB") as a catalyst were placed in a 1 L flask, and the liquid temperature was raised to 105°C while blowing air into it. Subsequently, the mixture was stirred for 10 hours while maintaining the temperature at 105°C. After that, the acid value was measured and confirmed to be 1.0 mg KOH / g, and the reaction was terminated. The epoxy groups in polymer a1-9 reacted with the carboxyl groups in M-5300 to obtain a solution of polymer A9 containing constituent units derived from methacrylate having acryloyl groups.

[0161] <Preparation of Polymer AA1> Polymer AA1 was obtained in the same manner as the preparation of Polymer A9, except that 21.1 parts by mass of ω-carboxy-polycaprolactone monoacrylate was replaced with 5.07 parts by mass of acrylic acid (hereinafter referred to as "AA"). Polymer AA1 is a polymer obtained by the reaction of epoxy groups contained in polymers a1-9 and carboxyl groups contained in AA, but it does not have (meth)acryloyl groups. In other words, polymer AA1 does not correspond to polymer (A).

[0162] Table 1 shows the physical properties of polymers a1-1 to a1-9, and the physical properties of polymers A1 to A9 and AA1. In Table 1, "(a2) / (a1)" refers to the molar ratio of reactive groups Y in (meth)acrylate (a2) to reactive groups X in polymer a1.

[0163] [Examples 1 to 17, Comparative Examples 1 to 2] Each component listed in Tables 2 and 3 was mixed and stirred to obtain the content (mass%) listed in Tables 2 and 3 to prepare an electron beam curable composition.

[0164] The details of compound (B1) are as follows: • Arronix M-321: Trimethylolpropane propylene oxide modified triacrylate (number of repeating propylene oxide groups: 6) • Arronix M-309: Trimethylolpropane triacrylate

[0165] The details of compound (B2) are as follows: • Arronix M-101A: Phenolethylene oxide modified acrylate (number of ethylene oxide groups: 2) • Arronix M-111: Nonylphenol ethylene oxide modified acrylate (number of ethylene oxide groups: 1) • Arronix M-120: 2-Ethylhexylethylene oxide modified acrylate (number of ethylene oxide groups: 2)

[0166] The following evaluations were performed using the obtained electron beam-curable composition.

[0167] <Reaction Rate> Cosmoshine A-4300 (product name, Toyobo's easy-adhesion PET film, film thickness: 50 μm) was prepared as a base film, and tape was attached to both ends. The electron beam curable composition was applied to the surface of the base film using an applicator so that the film thickness after drying was 90 μm to 110 μm. Next, it was dried in a forced-air dryer at 90°C for 60 minutes to obtain a coated film having a dried coating of the electron beam curable composition.

[0168] The obtained coated film was irradiated with an electron beam using an electron beam irradiation device manufactured by NHV Corporation under the conditions of an acceleration voltage of 150 kV, a dose of 100 kGy (adjusted by beam current and transport speed), and an oxygen concentration of 300 ppm or less, to obtain a film with a cured film. IR measurements were performed on the coated film and the film with the cured film using an ATR infrared spectrophotometer (Spectrum 100, Perkin Elmer). The reaction rate of the acryloyl group was 1730 cm⁻¹. －１ Based on the absorbance of 1406 cm², －１ The relative absorbance was determined, and the reaction rate of the acryloyl group before electron beam irradiation was set to 0%, and the reaction rate after electron beam irradiation was calculated according to the following formula (1). The reaction rate of the methacryloyl group was 1406 cm⁻¹ from the IR measurement of the acryloyl compound alone. －１ and 810cm －１ After separately calculating the ratio α of absorbances, 1730 cm －１ Based on the absorbance of 810 cm, －１ The relative absorbance was determined, and the reaction rate after irradiation was calculated according to the following formulas (2) and (3), assuming that the reaction rate of the methacryloyl group before irradiation was 0%.

[0169]

[0170]

[0171]

[0172] X (%): Reaction rate of acryloyl group Y (%): Reaction rate of methacryloyl group Abs. １ (1730cm) －１ ): 1730 cm before irradiation －１ Absorbance Abs.１ (1406 cm －１ ): Absorbance Abs. of 1406 cm －１ before irradiation. １ (810 cm －１ ): Absorbance Abs. of 810 cm －１ before irradiation. ２ (1730 cm －１ ): Absorbance Abs. of 1730 cm －１ after irradiation. ２ (1406 cm －１ ): Absorbance Abs. of 1406 cm －１ after irradiation. ２ (810 cm －１ ): Absorbance Abs. of 810 cm －１ after irradiation. ３ (1406 cm －１ ): Absorbance Abs. of 1406 cm －１ of the acryloyl compound alone. ３ (810 cm －１ ): Absorbance of 810 cm －１ of the acryloyl compound alone.

[0173] <Tensile properties> After cutting the film with a cured film into strips with a width of 60 mm × 10 mm, the cured film was peeled off from the base film. Using a tensile testing machine (Autograph AGS-J, manufactured by Shimadzu Corporation), the elongation at break (%) and the breaking strength (unit: MPa) of this cured film were measured under the conditions of a distance between chucks of 4 mm and a tensile speed of 5 mm / min, and the tensile product was calculated by the following formula. Tensile product (MPa·%) = Breaking strength (MPa) × Elongation at break (%).

[0174] <Solvent resistance> The surface of the film with a cured film was rubbed 100 times with a Kimwipe (registered trademark) impregnated with methyl ethyl ketone, with one reciprocation counted as one time. Then, the surface of the film with a cured film was visually observed. Evaluation was performed based on the presence or absence of changes before and after rubbing. A: No change B: Change (for example, changes such as cloudiness or scratches).

[0175] The evaluation results are shown in Tables 2 and 3.

[0176]

[0177]

[0178]

[0179] As shown in Tables 2 and 3, in Examples 1 to 17, it was found that the electron beam curable composition contained polymer (A) and compound (B1) having a trimethylolpropane structure and two or more ethylenically unsaturated groups, resulting in a cured product with excellent mechanical properties and excellent solvent resistance. On the other hand, in Comparative Example 1, compound (B1) was not included, and it was found to have poor solvent resistance. In Comparative Example 2, polymer (A) was not included, and it was found to have poor mechanical properties.

[0180] In Example 1, the (meth)acrylic equivalent of polymer (A) was 500 to 5,000 g / eq, and it was found to have superior mechanical properties compared to Examples 10 and 11.

[0181] In Example 1, the glass transition temperature of polymer (A) was -15°C to 90°C, and it was found to have superior mechanical properties compared to Examples 12 and 13.

[0182] In Example 1, because compound (B1) has an alkylene oxide group, it was found to have superior mechanical properties compared to Example 9.

[0183] Examples 5 to 7 were found to have superior mechanical properties compared to Example 1 because they contained compound (B2).

[0184] Furthermore, the disclosure of Japanese Patent Application No. 2024-225709, filed on December 20, 2024, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated as being incorporated by reference.

Claims

1. An electron beam curable composition comprising: a polymer (A) containing constituent units derived from a (meth)acrylate having a (meth)acryloyl group; and a compound (B1) having a trimethylolpropane structure and two or more ethylenically unsaturated groups.

2. The constituent unit derived from the (meth)acrylate having the (meth)acryloyl group is at least one selected from the group consisting of the constituent units represented by the following formulas (1A) to (1D). The electron beam curable composition according to claim 1. In formulas (1A) to (1D), R １１ , R １２ , R ２１ , R ２２ , R ３１ , R ３２ , R ４１ , and R ４２ each independently represents a divalent organic group, and R １０ , R １３ , R ２０ , R ２３ , R ３０ , R ３３ , R ４０ , and R ４３ each independently represents a hydrogen atom or a methyl group.

3. The electron beam curable composition according to claim 1, wherein the polymer (A) has (meth)acryloyl groups in its side chains and has a (meth)acrylic equivalent of 500 to 5,000 g / eq.

4. The electron beam curable composition according to claim 1, wherein the polymer (A) has a glass transition temperature of -15°C to 90°C.

5. The electron beam curable composition according to claim 1, wherein the compound (B1) further comprises an alkylene oxide group.

6. The electron beam curable composition according to claim 1, further comprising a compound (B2) having one ethylenically unsaturated group.

7. The electron beam curable composition according to claim 1, wherein the total content of the polymer (A) and the compound (B1) is 5% by mass to 95% by mass based on the total amount of the electron beam curable composition.

8. The electron beam curable composition according to claim 1, wherein the content of polymer (A) is 20% by mass to 90% by mass based on the total content of polymer (A) and compound (B1).

9. An electron beam curable composition used as a coating agent, according to any one of claims 1 to 8.

10. An electron beam curable composition according to any one of claims 1 to 8, used as an outdoor coating agent.

11. A method for producing an electron beam curable composition, comprising the steps of: reacting a polymer (a1) containing a constituent unit derived from a (meth)acrylate (a1-1) that does not have a reactive group and a constituent unit derived from a (meth)acrylate (a1-2) that has a reactive group X with a (meth)acrylate (a2) that has a reactive group Y that can react with the reactive group X to produce a polymer (A) containing a constituent unit derived from a (meth)acrylate that has a (meth)acryloyl group; and mixing the polymer (A) with a compound (B1) having a trimethylolpropane structure and two or more ethylenically unsaturated groups.

12. The method for producing an electron beam curable composition according to claim 11, wherein the reactive group X and the reactive group Y are an epoxy group, a carboxyl group, a hydroxyl group, or an isocyanate group.

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