Active energy ray curable composition and cured product

Abstract

The object of the present invention is to provide an active energy ray curable composition that gives a cured product with excellent flexibility and resilience, and further exhibits excellent storage stability. [Solution] An active energy ray curable composition comprising a monofunctional monomer (A), a polyfunctional (meth)acrylate (C) having a weight-average molecular weight of 6500 to 40000, water, and a photopolymerization initiator (D), wherein the monofunctional monomer (A) contains a monofunctional monomer (A1) having a homopolymer glass transition temperature of less than 25°C and a monofunctional monomer (A2) having a homopolymer glass transition temperature of 25°C or higher, and based on the total weight of (A) and (C), the content of (A) is 10 to 75% by weight, the content of (C) is 25 to 90% by weight, the content of the photopolymerization initiator (D) is 0.1 to 20% by weight, the water content is 0.005 to 0.5% by weight based on the weight of the active energy ray curable composition, and the inter-crosslinking molecular weight of the cured product is 5000 to 25000.

Description

[Technical Field]

[0001] This invention relates to an active energy ray curable composition and a cured product. [Background technology]

[0002] In recent years, there has been active development of so-called flexible displays that can be bent and stretchable devices that can be expanded and contracted. Accordingly, there is a demand for materials that can be expanded and contracted without breaking when bent or delamination between components. Furthermore, active energy ray curable compositions that have low viscosity at room temperature can be applied to many coating methods, including inkjet methods, and are used as materials for electronic components and optical components that require high-precision coating. In addition, there is a desire for flexible materials that can be attached to curved surfaces such as displays. Conventionally, stretchable UV resins have existed, but they had problems such as poor recovery rate and flexibility, or high elastic modulus which caused them to delaminate from other substrates when the device was pulled (Patent Document 1). Furthermore, these materials often lose their flexibility after long-term storage, and storage stability can sometimes be a challenge. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-70338 [Overview of the project] [Problems that the invention aims to solve]

[0004] The object of the present invention is to provide an active energy ray curable composition that gives a cured product with excellent flexibility and resilience, and further exhibits excellent storage stability. [Means for solving the problem]

[0005] The inventors of this invention arrived at the present invention as a result of diligent research to solve the above problems. In other words, the present invention relates to an active energy ray curable composition containing a monofunctional monomer (A), a polyfunctional (meth)acrylate (C) having a weight-average molecular weight of 6500 to 40000, water, and a photopolymerization initiator (D), wherein the monofunctional monomer (A) contains a monofunctional monomer (A1) having a homopolymer glass transition temperature of less than 25°C and a monofunctional monomer (A2) having a homopolymer glass transition temperature of 25°C or higher, and the monofunctional monomer (A) and the polyfunctional (meth)acrylate An active energy ray curable composition having, based on the total weight of the active energy ray curable composition, a content of monofunctional monomer (A) of 10 to 75% by weight, a content of polyfunctional (meth)acrylate (C) of 25 to 90% by weight, a content of photopolymerization initiator (D) of 0.1 to 20% by weight, an inter-crosslinking molecular weight of the cured product of 5000 to 25000, and a water content of 0.005 to 0.5% by weight based on the weight of the active energy ray curable composition, and a cured product obtained by curing the composition. [Effects of the Invention]

[0006] The active energy ray curable composition of the present invention exhibits excellent storage stability, and the cured product has excellent flexibility and resilience. [Modes for carrying out the invention]

[0007] The active energy ray curable composition of the present invention is an active energy ray curable composition containing a monofunctional monomer (A), a polyfunctional (meth)acrylate (C) having a weight-average molecular weight of 6500 to 40000, water, and a photopolymerization initiator (D).

[0008] In this invention, "(meth)acrylate" means "methacrylate or acrylate," "(meth)acrylic" means "methacrylic or acrylic," and "(meth)acryloyl" means "methacryloyl or acryloyl."

[0009] The essential components of the active energy ray curable composition of the present invention, namely the monofunctional monomer (A), the polyfunctional (meth)acrylate (C) having a weight-average molecular weight of 6,500 to 40,000, and the photopolymerization initiator (D), are described below in order.

[0010] Monofunctional monomer (A) contains monofunctional monomer (A1) whose homopolymer glass transition temperature is less than 25°C and monofunctional monomer (A2) whose homopolymer glass transition temperature is 25°C or higher.

[0011] Here, the glass transition temperature of a homopolymer is the temperature at which the loss tangent (tanδ) of a polymer obtained by homopolymerizing the monofunctional monomer using the method described below shows its maximum value. Monofunctional monomers such as aromatic groups, monofunctional monomers with alicyclic skeletons, and methyl methacrylate tend to have high glass transition temperatures, while (meth)acrylates with long-chain alkyl groups, urethane groups, and oxyalkylene groups tend to have low glass transition temperatures.

[0012] <Preparation of test pieces> (1) As a photoradical polymerization initiator, 1-hydroxycyclohexylphenyl ketone [trade name "Irgacure 184", manufactured by IGM Resins BV] is added at a concentration of 3% by weight relative to the monofunctional monomer, and the mixture is stirred until homogeneous to prepare a test piece sample. (2) Cut two 1mm thick silicone rubber sheets [product name: Silicone Rubber Sheet, manufactured by AS ONE Corporation] to 10mm wide x 150mm long and attach them to both ends of a glass plate [product name: GLASS PLATE, manufactured by AS ONE Corporation, 200mm high x 200mm wide x 5mm thick]. Place about 5g of the test piece sample between the silicone rubber sheets, cover with a PET film [product name: Lumirror S, manufactured by Toray Industries, Inc.] to prevent air from entering, and then cover with the glass plate to create a laminate. (3)(2) The laminate is subjected to ultraviolet irradiation at a temperature of 25°C using a UV irradiation device (e.g., Fusion UV Systems Japan VPS / I600, lamp: D bulb) to an illuminance of 1500 mW / cm². 2Irradiate with 1000 mJ / cm² in (UV-A). 2 Further, turn the laminate of (2) over and irradiate from the opposite side with 1000 mJ / cm² 2 to cure the composition. (4) Cut the cured sample of (3) into a test piece with a vertical width of 40 mm, a horizontal width of 5 mm, and a thickness of 1 mm.

[0013] <Dynamic viscoelasticity measurement method> Using this test piece, measure the dynamic viscoelasticity under the following conditions with a dynamic viscoelasticity measuring device (for example, Rheogel-E4000, manufactured by UBM). Measurement mode: Temperature dependence, measurement temperature range: -80°C to 200°C, frequency: 10 Hz, heating rate: 4°C / min, strain waveform: sine wave, measurement jig: tension The temperature at which the ratio (tanδ) of the loss elastic modulus E” to the storage elastic modulus E’ of the obtained spectrum becomes the maximum value is defined as the glass transition temperature (Tg).

[0014] The monofunctional monomer (A1) whose glass transition temperature of the homopolymer is less than 25°C is not particularly limited in chemical structure as long as the glass transition temperature of the homopolymer is less than 25°C. The monofunctional monomer (A1) whose glass transition temperature of the homopolymer is less than 25°C is preferably at least one selected from the group consisting of monofunctional (meth)acrylates (E) having a linear or branched alkyl group with 10 to 22 carbon atoms, monofunctional urethane (meth)acrylates (F), and other monofunctional (meth)acrylates (G).

[0015] Monofunctional (meth)acrylates (E) having linear or branched alkyl groups with 10 to 22 carbon atoms include decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and behenyl (meth)acrylate. These (meth)acrylates can be easily produced by direct esterification or transesterification reactions with natural or synthetic alcohols such as (meth)acrylic acid or methyl (meth)acrylate. When natural alcohols are used, the alkyl groups are linear and have an even number of carbon atoms. When synthetic alcohols are used, for example, when using Dovanol (manufactured by Mitsubishi Chemical Corporation), the alkyl groups are a mixture of linear and branched, and the number of carbon atoms is a mixture of odd and even. When using Diadol (manufactured by Mitsubishi Chemical Corporation), the alkyl groups are a mixture of linear and branched, and the number of carbon atoms is only odd. In the present invention, these monofunctional (meth)acrylates (E) having linear or branched alkyl groups with 10 to 22 carbon atoms may be used individually or in combination of two or more.

[0016] Among these monofunctional (meth)acrylates (E) having linear or branched alkyl groups with 10 to 22 carbon atoms, lauryl (meth)acrylate, isodecyl (meth)acrylate, and isostearyl (meth)acrylate are preferred from the viewpoint of flexibility of the cured product, strength of the cured product, and adhesion to the substrate.

[0017] In the present invention, monofunctional urethane (meth)acrylate (F) refers to a monomer having one (meth)acryloyl group and at least one urethane group in its molecule. From the viewpoint of viscosity, a monomer having one (meth)acryloyl group and one urethane group is preferred. Examples of monofunctional urethane (meth)acrylate (F) include reaction products of a monofunctional (meth)acrylate (a) having a hydroxyl group and an organic monoisocyanate compound (b).

[0018] Examples of monofunctional (meth)acrylates (a) having a hydroxyl group include hydroxyalkyl (the number of carbon atoms in the hydroxyalkyl group is preferably 2 to 4) (meth)acrylates (such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 1,4-cyclohexanedimethanol monoacrylate). Monofunctional (meth)acrylate (a) having a hydroxyl group may be used alone or in combination of two or more types.

[0019] Of these monofunctional (meth)acrylates (a) having hydroxyl groups, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred from the viewpoint of viscosity.

[0020] Examples of organic monoisocyanate compounds (b) include aliphatic monoisocyanate compounds (b1), alicyclic monoisocyanate compounds (b2), and aromatic monoisocyanate compounds (b3). Aliphatic monoisocyanate compounds (b1) include those having an alkyl group with 1 to 20 carbon atoms, such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, hexyl isocyanate, octyl isocyanate, lauryl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, and octadecyl isocyanate. Alicyclic monoisocyanate compounds (b2) include those having a hydrocarbon group with 5 to 13 carbon atoms and an alicyclic skeleton, such as cyclohexyl isocyanates. Aromatic monoisocyanate compounds (b3) include those having a hydrocarbon group with 6 to 12 carbon atoms that has an aromatic ring, such as phenyl isocyanate, tolylene isocyanate, and naphthyl isocyanate. Organic monoisocyanate compound (b) may be used alone or in combination of two or more types.

[0021] Of these organic monoisocyanate compounds (b), aliphatic monoisocyanate compounds (b1) and alicyclic monoisocyanate compounds (b2) are preferred from the viewpoint of the flexibility and viscosity of the cured product, more preferably aliphatic monoisocyanate compounds (b1), then even more preferably aliphatic monoisocyanate compounds having an alkyl group having 1 to 6 carbon atoms, and particularly preferably methyl isocyanate, ethyl isocyanate, propyl isocyanate, butyl isocyanate and hexyl isocyanate.

[0022] As the monofunctional urethane (meth)acrylate (F), a reaction product obtained by urethane-forming a monofunctional (meth)acrylate (a) having a hydroxyl group and an organic monoisocyanate compound (b) using a known method can be used. Alternatively, commercially available products can be used, such as Viscoat #216 (2-[(butylamino)carbonyl]oxyethyl acrylate: manufactured by Osaka Organic Chemical Industry Co., Ltd., homopolymer Tg 0℃), Etermer EM2080 (manufactured by Choko Material Industry Co., Ltd., homopolymer Tg 0℃), and Genomer 1122 (manufactured by RAHN, homopolymer Tg 7℃).

[0023] As for the monofunctional urethane (meth)acrylate (F), from the viewpoint of the flexibility and viscosity of the cured product, a urethane compound of hydroxyalkyl (meth)acrylate and an aliphatic monoisocyanate compound (b1), or a urethane compound of hydroxyalkyl (meth)acrylate and an alicyclic monoisocyanate compound (b2) is preferred, more preferably a urethane compound of hydroxyalkyl (hydroxyalkyl group with 2 to 4 carbon atoms) (meth)acrylate and an aliphatic monoisocyanate compound (b1), and particularly preferably a urethane compound of hydroxyalkyl (hydroxyalkyl group with 2 to 4 carbon atoms) (meth)acrylate and an aliphatic monoisocyanate having an alkyl group with 1 to 6 carbon atoms.

[0024] Other monofunctional (meth)acrylates (G) include (meth)acrylates having a heterocyclic skeleton containing an oxygen atom {e.g., tetrahydrofurfuryl acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, etc.}, alkyl (meth)acrylates having alkyl groups with 1 to 9 carbon atoms {e.g., methyl acrylate, ethyl acrylate, butyl acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, isoamyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, etc.}, and (meth)acrylates having an aromatic ring skeleton {e.g., benzyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4 Examples include 5-tetramethylphenyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc., 2-ethylhexyldiglycol (meth)acrylate, 2-ethylhexylcarbitol (meth)acrylate, fluorine atom-containing (meth)acrylate {for example, 2,2,2-tetrafluoroethyl (meth)acrylate, 1H,1H,2H,2H-perfluorodecyl (meth)acrylate, trifluoroethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, etc.}, trimethoxysilylpropyl (meth)acrylate, triethoxysilylpropyl (meth)acrylate, trimethylsilylpropyl (meth)acrylate, hydroxyethyl acrylate, methoxytriethylene glycol acrylate, etc. In the present invention, these other monofunctional (meth)acrylates (G) may be used individually or in combination of two or more. Other monofunctional (meth)acrylates (G) are preferably (meth)acrylates having a heterocyclic skeleton containing oxygen atoms, from the viewpoint of the tackiness of the cured product.

[0025] As monofunctional monomers (A1) having a glass transition temperature of less than 25°C for the homopolymer, preferred from the viewpoint of the flexibility of the cured product are lauryl acrylate (homopolymer Tg -30°C), (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (homopolymer Tg -7°C), 2-[(butylamino)carbonyl]oxoethyl acrylate (homopolymer Tg -0°C), tetrahydrofurfuryl acrylate (homopolymer Tg -12°C), and isostearyl acrylate. Lauryl acrylate (homopolymer Tg -18°C) is preferred, more preferably lauryl acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, 2-[(butylamino)carbonyl]oxoethyl acrylate, and tetrahydrofurfuryl acrylate, and particularly preferred lauryl acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, and tetrahydrofurfuryl acrylate.

[0026] As monofunctional monomers (A1) having a homopolymer glass transition temperature of less than 25°C, from the viewpoint of the flexibility of the cured product, those having a homopolymer glass transition temperature of -80 to 24°C are preferred, more preferably -60 to 20°C, and particularly preferably -40 to 10°C.

[0027] The monofunctional monomer (A2) having a glass transition temperature of 25°C or higher is not particularly limited in its chemical structure as long as the glass transition temperature of the homopolymer is 25°C or higher. Examples of monofunctional monomers (A2) having a glass transition temperature of 25°C or higher include methyl methacrylate, (meth)acrylate (H) having an alicyclic skeleton, monofunctional monomer (I) having a nitrogen atom in the molecule, and other monofunctional (meth)acrylates (J). From the viewpoint of curability, monofunctional monomer (I) having a nitrogen atom in the molecule is preferred.

[0028] As a monofunctional monomer (A2) having a homopolymer glass transition temperature of 25°C or higher, from the viewpoint of curability, it is preferable that the homopolymer has a glass transition temperature of 25 to 180°C, more preferably 30 to 170°C, and particularly preferably 40 to 160°C.

[0029] Examples of (meth)acrylates (H) having an alicyclic skeleton include isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 1-ethylcyclohexyl (meth)acrylate, and adamantyl (meth)acrylate. In the present invention, these alicyclic (meth)acrylate (H) compounds may be used individually or in combination of two or more.

[0030] Among these alicyclic skeleton-containing (meth)acrylates (H), isobornyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, and 1-ethylcyclohexyl (meth)acrylate are preferred from the viewpoint of the flexibility and strength of the cured product.

[0031] Examples of monofunctional monomers (I) having a nitrogen atom in the molecule include N-substituted vinyl monomers and N-substituted (meth)acrylamides, with N-substituted (meth)acrylamides being preferred from the viewpoint of curability. Examples of N-substituted vinyl monomers include N-vinylpyrrolidone, N-vinylcarbazole, N-vinylcaprolactam, N-vinylimidazole, and vinylmethyloxazolidinone. In the present invention, N-substituted (meth)acrylamide means a (meth)acrylamide in which one or two hydrogen atoms of the amino group are replaced with substituents such as hydrocarbon groups. Examples of N-substituted (meth)acrylamides include chain amides having an N-(meth)acryloyl group (I1), cyclic amides having an N-(meth)acryloyl group (I2), and diacetone acrylamide.

[0032] Examples of chain-like amides (I1) having an N-(meth)acryloyl group include N-alkyl(meth)acrylamide (I11), N,N-dialkyl(meth)acrylamide (I12), N-hydroxyalkyl(meth)acrylamide (I13), N-alkoxyalkyl(meth)acrylamide (I14), and N-alkyl-N-alkoxy(meth)acrylamide (I15).

[0033] Examples of N-alkyl(meth)acrylamide(I11) include N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-dodecyl(meth)acrylamide, and N-octadecyl(meth)acrylamide.

[0034] Examples of N,N-dialkyl(meth)acrylamide(I12) include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-dibutyl(meth)acrylamide, N,N-diisobutyl(meth)acrylamide, N,N-di-tert-butyl(meth)acrylamide, N,N-diheptyl(meth)acrylamide, N,N-dioctyl(meth)acrylamide, N,N-di-tert-octyl(meth)acrylamide, N,N-didodecyl(meth)acrylamide, and N,N-dioctadecyl(meth)acrylamide. The two alkyl groups of N,N-dialkyl(meth)acrylamide(I12) may be the same or different, and the number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 8, and particularly preferably 1 to 4 from the viewpoint of curability.

[0035] Examples of N-hydroxyalkyl(meth)acrylamide(I13) include N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N-(3-hydroxypropyl)(meth)acrylamide. From the viewpoint of curability, the number of carbon atoms in the alkyl group of N-hydroxyalkyl(meth)acrylamide(I13) is preferably 1 to 20, more preferably 1 to 8, and particularly preferably 1 to 4.

[0036] Examples of N-alkoxyalkyl(meth)acrylamide(I14) include N-methoxymethyl(meth)acrylamide, N-ethoxymethyl(meth)acrylamide, N-propoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-ethoxyethyl(meth)acrylamide, N-butoxyethyl(meth)acrylamide, N-methoxypropyl(meth)acrylamide, N-ethoxypropyl(meth)acrylamide, N-methoxybutyl(meth)acrylamide, and N-ethoxybutyl(meth)acrylamide. From the viewpoint of curability, the number of carbon atoms in the alkoxyalkyl group of N-alkoxyalkyl(meth)acrylamide(I14) is preferably 2 to 20, more preferably 2 to 8, and particularly preferably 2 to 6. From the viewpoint of curability, the number of carbon atoms in the alkyl group of the alkoxyalkyl group is preferably 1 to 4, more preferably 1 to 3, and particularly preferably 1 to 2.

[0037] Examples of N-alkyl-N-alkoxy(meth)acrylamide (I15) include N-methyl-N-methoxy(meth)acrylamide, N-methyl-N-ethoxy(meth)acrylamide, N-methyl-N-propoxy(meth)acrylamide, N-methyl-N-butoxy(meth)acrylamide, N-ethyl-N-methoxy(meth)acrylamide, N-ethyl-N-ethoxy(meth)acrylamide, N-ethyl-N-butoxy(meth)acrylamide, N-propyl-N-methoxy(meth)acrylamide, N-propyl-N-ethoxy(meth)acrylamide, N-butyl-N-methoxy(meth)acrylamide, and N-butyl-N-ethoxy(meth)acrylamide.

[0038] Examples of cyclic amides (I2) having an N-(meth)acryloyl group include N-(meth)acryloylmorpholine, N-(meth)acryloylthiomorpholine, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, and N-(meth)acryloylpiperidine. The number of carbon atoms in the cyclic amide having an N-(meth)acryloyl group is preferably 7 to 20, more preferably 7 to 18, and particularly preferably 7 to 16, from the viewpoint of curability. In the present invention, these N-substituted (meth)acrylamides may be used individually or in combination of two or more.

[0039] Of these N-substituted (meth)acrylamides, those preferred from the viewpoint of viscosity, curability and flexibility of the cured product are N,N-dialkyl(meth)acrylamide (I12), N-alkoxyalkyl(meth)acrylamide (I14), and cyclic amides (I2) having an N-(meth)acryloyl group. More preferably, these are N,N-dialkyl(meth)acrylamide (I12) and cyclic amides (I2) having an N-(meth)acryloyl group. Particularly preferred are N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and N-(meth)acryloylmorpholine.

[0040] Other monofunctional (meth)acrylates (J) include cyclic trimethylolpropaneform (meth)acrylate, etc.

[0041] From the viewpoint of the flexibility of the cured product, the monofunctional monomers (A2) with a glass transition temperature of 25°C or higher are preferably N-acryloylmorpholine (homopolymer Tg 145°C), N,N-dimethylacrylamide (homopolymer Tg 119°C), N,N-diethylacrylamide (homopolymer Tg 81°C), isobornyl acrylate (homopolymer Tg 97°C), t-butylcyclohexyl acrylate (homopolymer Tg 65°C), cyclic trimethylolpropane formal acrylate (homopolymer Tg 27°C), and diacetone acrylamide (homopolymer Tg 77°C).

[0042] The molecular weight (sum of the products of atomic weight and number of atoms based on the chemical formula) of the monofunctional monomer (A) is preferably 100 to 500, and more preferably 150 to 400, from the viewpoint of the resilience of the cured product.

[0043] In this invention, the polyfunctional (meth)acrylate (C) has a weight-average molecular weight of 6500 to 40000. If the weight-average molecular weight is less than 6500, it is not possible to achieve both flexibility and elastic modulus in the cured product, and if it exceeds 40000, the elastic modulus of the cured product is not satisfactory. The weight-average molecular weight of the polyfunctional (meth)acrylate (C) is preferably 8,000 to 36,000, and more preferably 10,000 to 30,000. In the present invention, the weight-average molecular weight of the polyfunctional (meth)acrylate (C) can be measured by gel permeation chromatography (GPC). Specifically, it can be measured using the following measurement method. <Method for measuring the weight-average molecular weight of polyfunctional (meth)acrylate (C)> The sample was dissolved in tetrahydrofuran, filtered to remove impurities, and then the GPC instrument was set up under the following conditions to equilibrate the column. The sample was injected and measured. The obtained weight-average molecular weight was expressed as a relative value on a polystyrene basis. Device name: HLC-8320 (manufactured by Tosoh Corporation) Column: (Example: PLgel 5μm MIXED-C, Molecular weight range: 200~2,000,000) Mobile phase: Dimethylformamide Flow rate: 1.0ml / min Column temperature: 35℃ Detector: Differential refractive index detector

[0044] As a polyfunctional (meth)acrylate (C) with a weight-average molecular weight of 6,500 to 40,000, a bifunctional (meth)acrylate (L) with a weight-average molecular weight of 6,500 to 40,000 is preferred from the viewpoint of the flexibility of the cured product and the elastic modulus of the cured product.

[0045] Examples of bifunctional (meth)acrylates (L) include di(meth)acrylates (L1) of alkylene oxide adducts (alkylene groups with 2 to 4 carbon atoms) of divalent phenol compounds (e.g., 90 to 500 moles added), diesterified (meth)acrylic acid of alkylene oxide adducts (alkylene groups with 2 to 4 carbon atoms) of divalent alcohols with 2 to 30 carbon atoms (e.g., 90 to 500 moles added), di(meth)acrylates of ethylene oxide adducts of fluorene, and urethane diacrylates (L3). Of these, urethane diacrylates (L3) are preferred from the viewpoint of the restorability of the cured product.

[0046] Examples of di(meth)acrylate (L1) divalent phenol compounds include monocyclic phenols (catechol, resorcinol, hydroquinone, etc.), condensed polycyclic phenols (dihydroxynaphthalene, etc.), and bisphenol compounds (bisphenol A, bisphenol F, and bisphenol S, etc.). Examples of di(meth)acrylates (L1) include, for example, the di(meth)acrylate of the ethylene oxide (hereinafter, ethylene oxide may be abbreviated as EO) adduct of catechol, the di(meth)acrylate of the propylene oxide (hereinafter, 1,2- or 1,3-propylene oxide may be abbreviated as PO) adduct of dihydroxynaphthalene, and the di(meth)acrylate of the EO adduct of bisphenol A.

[0047] In the diesterified product (L2), the dihydric alcohols having 2 to 30 carbon atoms include straight-chain aliphatic diols (e.g., ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-dodecanediol, etc.) and branched aliphatic diols (e.g., 1,2-propanediol, 1,2-, 1,3- or 2,3-butanediol, 2-methyl-1,4-butanediol). Examples include ols, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,5-pentanediol and 3-methyl-1,5-pentanediol, etc., and alicyclic diols (e.g., 1,2-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 1,4-bis(hydroxymethyl)cyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane, etc.). Examples of diesterized products (L2) include (meth)acrylic acid diesters of polyethylene glycol, (meth)acrylic acid diesters of polypropylene glycol, and (meth)acrylic acid diesters of polytetramethylene glycol.

[0048] Urethane diacrylate (L3) is a urethane (meth)acrylate containing polyol (m), polyisocyanate (n), and active hydrogen group-containing (meth)acrylate (c) as constituent raw materials.

[0049] Examples of polyols (m) include linear aliphatic polyols (m1) having 1 to 20 carbon atoms, alicyclic polyols (m2) having 6 to 20 carbon atoms, aromatic polyols (m3) having 6 to 20 carbon atoms, and adducts thereof with alkylene oxides [ethylene oxide (EO), 1,2- or 1,3-propylene oxide (PO), and 1,2-, 1,3-, 1,4- or 2,3-butylene oxide, etc.].

[0050] Examples of linear aliphatic polyols (m1) include straight-chain aliphatic diols with 1 to 20 carbon atoms (ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-dodecanediol, etc.) and branched aliphatic diols (1,2-propanediol, 1,2-, 1, Examples include 3- or 2,3-butanediol, 2-methyl-1,4-butanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,5-pentanediol, and 3-methyl-1,5-pentanediol, etc., and linear aliphatic tri- to octavalent alcohols (such as pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, and dipentaerythritol).

[0051] Examples of alicyclic polyols (m2) having 6 to 20 carbon atoms include 1,2-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 1,4-bis(hydroxymethyl)cyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane, and 1,3,5-cyclohexanetriol.

[0052] Examples of aromatic polyols (m3) having 6 to 20 carbon atoms include resorcinol, hydroquinone, naphthalenediol, and bisphenols (bisphenol A, bisphenol F, and bisphenol S, etc.).

[0053] When using an alkylene oxide adduct of the aforementioned linear aliphatic polyol (m1), alicyclic polyol (m2), or aromatic polyol (m3) as the polyol (m), the number of moles of alkylene oxide added is preferably 1 to 50 moles, and more preferably 4 to 30 moles, from the viewpoint of the elongation of the cured product.

[0054] Of these polyols (m), from the viewpoint of elongation of the cured product, alkylene oxide adducts of the aforementioned linear aliphatic polyol (m1) are preferred, more preferably 1,4-butylene oxide adducts of aliphatic polyol (m1) are preferred, and particularly preferably poly-1,4-butylene oxide (polytetramethylene glycol) is preferred. Polyol(m) may be used individually or in combination of two or more types.

[0055] Examples of polyisocyanates (n) include linear aliphatic polyisocyanates (n1) having 4 to 20 carbon atoms, alicyclic polyisocyanates (n2) having 6 to 22 carbon atoms, and aromatic polyisocyanates (n3) having 8 to 22 carbon atoms.

[0056] Examples of chain-like aliphatic polyisocyanates (n1) having 4 to 20 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0057] Examples of alicyclic polyisocyanates (n2) having 6 to 22 carbon atoms include cyclohexane-1,3-diylbismethylene diisocyanate, isophorone diisocyanate (IPDI), 2,4- or 2,6-methylcyclohexane diisocyanate (hydrogenated TDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI; hereafter sometimes referred to as MDIH), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexylene-1,2-dicarboxylate, 2,5- or 2,6-norbornane diisocyanate, and dimer acid diisocyanate.

[0058] Examples of aromatic polyisocyanates (n3) having 8 to 22 carbon atoms include 1,3- or 1,4-phenylenediisocyanate, 2,4- or 2,6-tolylenediisocyanate (TDI), 4,4'- or 2,4'-diphenylmethanediisocyanate (MDI), m- or p-isocyanatophenylsulfonyl isocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylenediisocyanate, m- or p-isocyanatophenylsulfonyl isocyanate, m- or p-xylylenediisocyanate (XDI), and α,α,α',α'-tetramethylxylylenediisocyanate (TMXDI).

[0059] Of these polyisocyanates (n), from the viewpoint of elongation and light resistance of the cured product, preferably are alicyclic polyisocyanates (n2) having 6 to 22 carbon atoms and aromatic polyisocyanates (n3) having 8 to 22 carbon atoms, more preferably alicyclic polyisocyanates having 6 to 20 carbon atoms and aromatic polyisocyanates having 8 to 20 carbon atoms, particularly preferably cyclohexane-1,3-diylbismethylene diisocyanate, IPDI, XDI, TMXDI, MDI, and TDI, with IPDI being the most preferred. Polyisocyanate (n) may be used alone or in combination of two or more types.

[0060] Examples of active hydrogen group-containing (meth)acrylates (c) include hydroxyl group-containing (meth)acrylate (c1), amino group-containing (meth)acrylate (c2), and carboxyl group-containing (meth)acrylate (c3). Of these, the preferred is the hydroxyl group-containing (meth)acrylate. Examples of hydroxyl group-containing (meth)acrylates (C1) include hydroxyalkyl (meth)acrylates (C11) and polyalkylene glycol mono(meth)acrylates (C12).

[0061] Preferably, the hydroxyalkyl (meth)acrylate (C11) is a hydroxyalkyl (meth)acrylate having 4 to 20 carbon atoms, and specifically, examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate.

[0062] Examples of polyalkylene glycol mono(meth)acrylate (C12) include polyethylene glycol mono(meth)acrylate and polypropylene glycol mono(meth)acrylate.

[0063] Examples of amino group-containing (meth)acrylates (C2) include monoalkyl (1-4 carbon atoms) aminoalkyl (2-6 carbon atoms) (meth)acrylates {aminoethyl, aminopropyl, methylaminoethyl, ethylaminoethyl, butylaminoethyl, or methylaminopropyl (meth)acrylate}.

[0064] Examples of carboxyl group-containing (meth)acrylates (C3) include 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl phthalic acid, and 2-(meth)acryloyloxyethyl hexahydrophthalic acid.

[0065] Among the active hydrogen group-containing (meth)acrylates (c), hydroxyl group-containing (meth)acrylate (c1) is preferred from the viewpoint of reactivity in the urethane reaction and elongation of the cured product, more preferably hydroxyl group-containing monofunctional (meth)acrylate, particularly preferably hydroxyalkyl (meth)acrylate (c11), and most preferably 2-hydroxyethyl (meth)acrylate. The active hydrogen group-containing (meth)acrylate (c) may be used alone or in combination of two or more types. The aforementioned urethane diacrylate (L3) may be used alone or in combination of two or more types.

[0066] Regarding the constituent raw materials of the urethane diacrylate (L3) described above, polyol (m), polyisocyanate (n), and active hydrogen group-containing (meth)acrylate (c), the molar ratio of isocyanate groups in polyisocyanate (n) to active hydrogen groups in polyol (m) and active hydrogen group-containing (meth)acrylate (c) [(isocyanate groups in (n) / total active hydrogen groups in (m) and (c)] is not particularly limited, but from the viewpoint of storage stability, it is preferably 1 / 0.5 to 1 / 10, more preferably 1 / 0.7 to 1 / 5, and particularly preferably 1 / 1 to 1 / 2.

[0067] The urethane diacrylate (L3) in the present invention can be produced by reacting a polyol (m), a polyisocyanate (n), and an active hydrogen group-containing (meth)acrylate (c) by known methods. In particular, it is preferable to produce a urethane prepolymer having two or more isocyanate groups by polyaddition reaction of a polyol (m) and a polyisocyanate (n), and then to produce it by addition reaction of an active hydrogen group-containing (meth)acrylate (c). In the polyaddition and addition reactions described above, a urethane catalyst may be used. Examples of urethane catalysts include metal compounds (organobismuth compounds, organotin compounds, and organotitanium compounds, etc.) and quaternary ammonium salts.

[0068] The polyfunctional (meth)acrylate (C) having a weight-average molecular weight of 6500 to 40000 may be a (meth)acrylate with three or more functions, such as urethane tetraacrylate.

[0069] The photopolymerization initiator (D) is not limited as long as it generates radicals and ions, etc., upon irradiation with active energy rays to cause a monomer polymerization reaction, and a photopolymerization initiator that generates radicals upon irradiation with active energy rays is preferably used. Preferred photopolymerization initiators (D) include acylphosphine oxide compounds (D1), α-hydroxyalkylphenone compounds (D2), α-aminoalkylphenone compounds (D3), ketal compounds (D4), benzoylformate compounds (D5), thioxanthone compounds (D6), benzophenone compounds (D7), and oxime ester compounds (D8).

[0070] Examples of acylphosphine oxide compounds (D1) include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl(2,4,6-trimethylbenzoyl)-phenylphosphenate, and ethyl 2,4,6-trimethylbenzoylphenylphosphinate.

[0071] Examples of α-hydroxyalkylphenone compounds (D2) include 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-phenylpropan-1-one.

[0072] Examples of α-aminoalkylphenone compounds (D3) include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-butan-1-one, and 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-butan-1-one.

[0073] Examples of ketal compounds (D4) include benzyldimethyl ketal.

[0074] Examples of benzoylformate compounds (D5) include methylbenzoylformate.

[0075] Examples of thioxanthone compounds (D6) include 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 2-chlorothioxanthone.

[0076] Examples of benzophenone compounds (D7) include benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 4,4'-bismethylaminobenzophenone.

[0077] Examples of oxime ester compounds (D8) include 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime) and 1-[6-(2-methylbenzoyl)-9-ethyl-9H-carbazole-3-yl]-ethanone-1-(O-acetyl oxime). In the present invention, these photopolymerization initiators (D) may be used individually or in combination of two or more.

[0078] Of these photopolymerization initiators (D), those preferred from the viewpoint of curability and transmittance of the cured product are acylphosphine oxide compounds (D1), α-hydroxyalkylphenone compounds (D2), and α-aminoalkylphenone compounds (D3), more preferably α-hydroxyalkylphenone compounds (D2) and α-aminoalkylphenone compounds (D3), and particularly preferably 1-hydroxycyclohexylphenyl ketone and 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone.

[0079] The content of monofunctional monomer (A) in this invention is 10 to 75% by weight, based on the total weight of monofunctional monomer (A) and polyfunctional (meth)acrylate (C). If the content of monofunctional monomer (A) is less than 10% by weight, the flexibility of the cured product will be insufficient, and if it exceeds 75% by weight, the resilience of the cured product will be insufficient.

[0080] In the present invention, the content of monofunctional monomer (A1) having a glass transition temperature of less than 25°C in the homopolymer is preferably 5 to 30% by weight, and more preferably 5 to 25% by weight, based on the total content of monofunctional monomer (A) and polyfunctional (meth)acrylate (C), from the viewpoint of curability and flexibility.

[0081] The content of monofunctional monomer (A2) with a glass transition temperature of 25°C or higher in the homopolymer is preferably 5 to 70% by weight, based on the total weight of monofunctional monomer (A) and polyfunctional (meth)acrylate (C), from the viewpoint of curability and flexibility.

[0082] In the present invention, the weight ratio (A1) / (A2) of monofunctional monomers (A1) in the composition having a homopolymer glass transition temperature of less than 25°C to monofunctional monomers (A2) having a homopolymer glass transition temperature of 25°C or higher is preferably 0.50 to 2.0 from the viewpoint of curability (tackiness), flexibility of the cured product, and restorability of the cured product.

[0083] In this invention, the content of polyfunctional (meth)acrylate (C) is 25 to 90% by weight, based on the total weight of monofunctional monomer (A) and polyfunctional (meth)acrylate (C). If the content of polyfunctional (meth)acrylate (C) is less than 25% by weight, the resilience of the cured product is insufficient, and if it exceeds 90% by weight, the flexibility is insufficient.

[0084] In the present invention, the weight ratio (A) / (C) of monofunctional monomer (A) to polyfunctional monomer (C) in the composition is preferably 0.05 to 2.0, and more preferably 0.1 to 1.5, from the viewpoint of the restorability of the cured product.

[0085] The content of the photopolymerization initiator (D) in the present invention is 0.1 to 20% by weight, preferably 2 to 20% by weight, more preferably 2 to 18% by weight, and even more preferably 5 to 15% by weight, based on the total weight of the monofunctional monomer (A) and the polyfunctional (meth)acrylate (C). If the content of the photopolymerization initiator (D) is less than 0.1% by weight, the curing performance will be insufficient, and if it exceeds 20% by weight, the transmittance of the cured product will be insufficient.

[0086] The inter-crosslinking molecular weight of the cured product in this invention is 5,000 to 25,000. If the inter-crosslinking molecular weight is less than 5,000, it is not possible to achieve both flexibility and elastic modulus in the cured product, and if it exceeds 25,000, the elastic modulus of the cured product will not be satisfactory. The inter-crosslinking molecular weight can be increased, for example, by increasing the proportion of monomer components with a small number of functional groups and a large weight-average molecular weight, and can be decreased by increasing the proportion of components with a large number of functional groups and a small weight-average molecular weight. The molecular weight between the crosslinking points is expressed as [Mc](g / mol). The molecular weight between crosslinking points is preferably 6,000 to 20,000 (g / mol), and more preferably 10,000 to 15,000 (g / mol), from the viewpoint of the flexibility and elastic modulus of the cured product. The molecular weight between crosslinking points [Mc] (g / mol) can be calculated by the following formula (1). [Mc]=1 / {a0×(1 / Mc0)+a1×(1 / Mc1)+···+a i ×(1 / Mc i) + ··· + a n × (1 / Mc n )} (1) In the above calculation formula (1), a0, a1, ··· a i , ··· a n represent the weight percentages of the respective components of the monomers constituting (hereinafter abbreviated as each component). Also, Mc0, Mc1, ··· Mc i , ··· Mc n represent the molecular weight between crosslinking points for each component. Note that [Mc i (g / mol) can be calculated by the following calculation formula (2). [Mc i = Mw / {2 × (n - 1)} (2) In the above calculation formula (2), for the monofunctional monomer (A), Mw is its molecular formula weight, and for the others (polyfunctional (meth)acrylate (C), etc.), Mw is its weight average molecular weight (g / mol). n represents the number of (meth)acryloyl groups possessed by each component (n is 2 or more).

[0087] The water content of the active energy ray-curable composition of the present invention is 0.005 to 0.5% by weight based on the weight of the active energy ray-curable composition. If it is less than 0.005% by weight, the flexibility is poor, and if it exceeds 0.5% by weight, the storage stability of the active energy ray-curable composition is poor. The water content can be adjusted, for example, by subjecting the components to dehydration under reduced pressure or adding water after blending the components. The water content of the active energy ray-curable composition can be measured in accordance with JIS K0113. Specifically, it can be determined by performing coulometric titration using methanol as a solvent by the Karl Fischer method in accordance with JIS K0113 using a trace moisture measuring device "AQV-300" manufactured by Hiranuma Sangyo Co., Ltd. The water content of the active energy ray-curable composition of the present invention is preferably 0.01 to 0.4% by weight, more preferably​​​The acid value (mgKOH / g) of the active energy ray curable composition of the present invention is preferably 0.01 to 1.5, more preferably 0.01 to 1.0, and particularly preferably 0.01 to 0.5, from the viewpoint of storage stability of the active energy ray curable composition and storage stability of the cured product. The acid value can be increased by using (meth)acrylic acid as the monofunctional monomer (A) or by hydrolyzing the monofunctional monomer (A), and can be decreased by removing (meth)acrylic acid by treating the active energy ray curable composition under reduced pressure. The acid value of the active energy ray curable composition can be measured in accordance with JIS K0070.

[0089] The active energy ray curable composition of the present invention may contain other monomers (M) other than monofunctional monomers (A) and polyfunctional (meth)acrylates (C) having a weight-average molecular weight of 6500 to 40000, as long as they do not inhibit the effects of the present invention. Other monomers (M) include bifunctional or higher (meth)acrylates with a molecular weight or weight-average molecular weight of less than 6500 or greater than 40000 [for example, bifunctional (meth)acrylate (N), trifunctional or higher (meth)acrylate (O), and (meth)acrylate (P) having a phosphate group]. Furthermore, in the present invention, if monomers having cationic polymerizable groups such as vinyl ether groups and N-vinyl groups are used, the storage stability of the active energy ray curable composition may be insufficient, so it is preferable not to use them.

[0090] As bifunctional (meth)acrylates (N), those with a molecular weight or weight-average molecular weight of less than 6500 or more than 40000 include alkylene glycol di(meth)acrylates {e.g., ethylene glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, etc.}, polyalkylene glycol (alkylene group with 2-4 carbon atoms) di(meth)acrylate (N1), di(meth)acrylates (N2) of alkylene oxide (alkylene group with 2-4 carbon atoms) adducts of divalent phenol compounds, and polyalkylene glycol (alkylene group with 2-30 carbon atoms) Examples include diesterified (meth)acrylic acid diesters of alkylene oxide adducts (alkylene group with 2-4 carbon atoms) of valent (preferably 2-8 valent) alcohols, diesterified (meth)acrylic acid diesters of diglycidyl ether and (meth)acrylic acid, di(meth)acrylates of ethylene oxide adducts of fluorene, cyclohexanemethanol di(meth)acrylate, ethoxylated cyclohexanemethanol di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, and 1,3-adamantyldiol di(meth)acrylate.

[0091] In the present invention, these bifunctional (meth)acrylates (N) may be used individually or in combination of two or more.

[0092] Examples of (meth)acrylate(O) with three or more functions include trifunctional (meth)acrylate monomers and tetrafunctional (meth)acrylate monomers.

[0093] Examples of trifunctional (meth)acrylate monomers include trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane modified tri(meth)acrylate with 3-4 carbon atoms alkylene oxide, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, trimethylolpropane tri((meth)acryloyloxypropyl) ether, sorbitol tri(meth)acrylate, tri(meth)acrylate of pentaerythritol added to 1-30 molars of 3-4 carbon atoms alkylene oxide, and ethoxylated glycerin tri(meth)acrylate.

[0094] Examples of (meth)acrylate monomers with four or more functions include pentaerythritol tetra(meth)acrylate, sorbitol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol propionic acid tetra(meth)acrylate, tetra(meth)acrylate of 1 to 11 molar adducts of 3-4 carbon atoms of pentaerythritol, sorbitol penta(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. In the present invention, these three- or more functional (meth)acrylate (O) can be used individually or in combination of two or more.

[0095] The (meth)acrylate (P) having a phosphate group is not limited as long as it is a phosphate ester having a (meth)acryloyl group, and examples include those with 1 to 3 (meth)acryloyl functional groups. It is possible to use commercially available products, such as 2-methacryloyloxyethyl acid phosphate (Unichemical, Fosmer M), acid phosphopolyoxyethylene glycol monomethacrylate (Unichemical, Fosmer PE), acid phosphopolyoxypropylene glycol monomethacrylate (Unichemical, Fosmer PP), 2-acryloyloxyethyl acid phosphate (Kyoeisha Chemical, Light Acrylate P-1A(N)), 2-methacryloyloxyethyl acid phosphate (Kyoeisha Chemical, Light Ester P-1M), bis(2-methacryloyloxyethyl) acid phosphate (Kyoeisha Chemical, Light Ester P-2M), and bis(2-methacryloyloxyethyl) acid phosphate (Nippon Kayaku, KAYAMER). Examples include PM-2) and the reaction product of a 6-hexanolide addition polymer of 2-hydroxyethyl methacrylate and phosphoric acid anhydride (manufactured by Nippon Kayaku Co., Ltd., KAYAMER PM-21). In the present invention, these (meth)acrylates (P) having phosphate groups may be used individually or in combination of two or more.

[0096] Among the (meth)acrylates (P) having phosphate groups, from the viewpoint of metal adhesion, (meth)acrylates having phosphate groups with 1 to 2 functional groups of (meth)acryloyl groups are preferred, and more preferably are reaction products of 6-hexanolide addition polymers of 2-(meth)acryloyloxyethyl acid phosphate, bis{2-(meth)acryloyloxyethyl} acid phosphate, and 2-hydroxyethyl methacrylate with phosphoric anhydride.

[0097] The content of other monomers (M) is preferably 0 to 20% by weight, and more preferably 0 to 10% by weight, based on the total weight of monofunctional monomers (A) and polyfunctional (meth)acrylates (C), from the viewpoint of flexibility and adhesion.

[0098] The active energy ray curable composition of the present invention may contain various additives as needed, as long as they do not inhibit the effects of the present invention. Examples of additives include leveling agents, charge regulators, light stabilizers, UV absorbers, surface treatment agents, antioxidants, anti-aging agents, crosslinking accelerators, plasticizers, preservatives, pH adjusters, defoamers, and humectants.

[0099] The method for producing the active energy ray-curable composition of the present invention is not particularly limited. For example, the above components can be mixed by stirring them in a suitable container such as a glass beaker, can, or plastic cup using a stirring rod, spatula, etc., or by uniformly mixing them using a known mixing device (such as a mechanical stirrer or magnetic stirrer, a mixing device equipped with a stirring spring such as a paddle, a dissolver, a ball mill, or a planetary mixer). The active energy ray curable composition of the present invention is preferably liquid at room temperature, and its viscosity can be measured using an E-type viscometer [such as the "VISCOMETER TV-25L" manufactured by Toki Sangyo Co., Ltd.] and a B-type viscometer.

[0100] To obtain a cured product of an active energy ray curable composition, the active energy ray curable composition is applied to a substrate by a known method, and then cured by irradiation with active energy rays. Examples of active energy rays in this invention include ultraviolet rays and electron beams. The active energy rays used for curing the active energy ray-curable composition of the present invention can be adjusted by selecting a photopolymerization initiator. When the aforementioned photopolymerization initiator (D) is used, photocuring is possible by irradiation with active energy rays having a wavelength of 200 to 700 nm, and it is preferable that curing is possible by irradiation with light (ultraviolet light) having a wavelength of 200 to 400 nm.

[0101] As light sources that emit ultraviolet light, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and high-power metal halide lamps can be used (Latest Trends in UV / EB Curing Technology, edited by Radtech Research Group, CMC Publishing, p. 138, 2006), as well as LEDs. Among these, LEDs consume less power and generate less ozone compared to other light sources, resulting in lower running costs and a smaller environmental impact. When curing with an LED light source, an LED light source ultraviolet irradiation device [for example, LED light source ultraviolet irradiation device "FJ100 150×20 365, phoseon", manufactured by TECHNOLOGY Co., Ltd.] can be used. The amount of ultraviolet light irradiated when curing the active energy ray-curable composition of the present invention is preferably 10 to 10,000 mJ / cm² from the viewpoint of curability and flexibility of the cured product. 2 More preferably 50 to 5,000 mJ / cm² 2 That is the case. When irradiating with the aforementioned electron beam, a known electron beam irradiation device can be used. The electron beam irradiation dose is preferably 1 to 10 Mrad from the viewpoint of curability and suppression of deterioration of the cured product.

[0102] The substrate to which the active energy ray-curable composition of the present invention is applied can be appropriately selected according to the application, and organic materials such as plastics, or inorganic materials such as metals and glass can be used. Examples of metals include steel, hot-dip galvanized steel, electro-galvanized steel, tinplate, tin-free steel, various other plated or alloy-plated steels, stainless steel, aluminum, gold, platinum, silver, and copper. Furthermore, various surface treatments such as phosphate treatment, chromate treatment, organic phosphate treatment, organic chromate treatment, and heavy metal substitution treatment may be applied. Examples of plastic materials include polyester resins {polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), etc.}, acrylic resins (methyl methacrylate copolymers, etc.), triacetylcellulose, acrylonitrile-butadiene-styrene copolymer (ABS) resin, styrene resin, polysulfone resin, polyethersulfone resin, polycarbonate resin, vinyl chloride resin, polymethacrylimide resin, and polyolefin resins (polyethylene, polypropylene, and cycloolefin polymers, etc.). Examples of inorganic materials include glass and ceramics. Of these, the active energy ray curable composition of the present invention exhibits particularly excellent adhesion to metals.

[0103] As a method for applying the active energy ray-curable composition of the present invention to a substrate, known coating methods such as spin coating, roll coating, and spray coating, as well as known printing methods such as lithographic printing, cardboard printing, metal printing, offset printing, screen printing, and gravure printing, can be applied. Furthermore, since the composition of the present invention has low viscosity at room temperature, it can also be applied to inkjet coating methods (inkjet printing) that continuously eject fine droplets. Inkjet printing allows for precise and high-speed printing with relatively simple equipment, making it ideally suited for the manufacture of display components such as liquid crystal displays and organic EL displays, as well as other electronic and optical components.

[0104] The active energy ray curable composition of the present invention has low viscosity, and the cured product of the active energy ray curable composition exhibits excellent elongation and elastic modulus, making it useful as a material for various electronic and optical components, including display components. In particular, it can be suitably used for bonding and sealing applications of electronic components such as display components and image sensors, and semiconductor packages. It can also be widely used for various coatings, inks (UV printing inks and UV inkjet printing inks, etc.), and paints.

[0105] The present application is as follows: <1> ~ <5> The invention is disclosed. <1> An active energy ray curable composition comprising a monofunctional monomer (A), a polyfunctional (meth)acrylate (C) having a weight-average molecular weight of 6500 to 40000, water, and a photopolymerization initiator (D), wherein the monofunctional monomer (A) comprises a monofunctional monomer (A1) having a homopolymer glass transition temperature of less than 25°C and a monofunctional monomer (A2) having a homopolymer glass transition temperature of 25°C or higher, and based on the total weight of the monofunctional monomer (A) and the polyfunctional (meth)acrylate (C), the content of the monofunctional monomer (A) is 10 to 75% by weight, the content of the polyfunctional (meth)acrylate (C) is 25 to 90% by weight, the content of the photopolymerization initiator (D) is 0.1 to 20% by weight, the content of water is 0.005 to 0.5% by weight, and the inter-crosslinking molecular weight of the cured product is 5000 to 25000. <2> The acid value of the aforementioned active energy ray-curable composition is 0.01 to 1.5 mg KOH / g. <1> The activated energy ray curable composition described above. <3> The monofunctional monomer (A2) is a monofunctional monomer having a nitrogen atom in its molecule. <1> or <2> The activated energy ray curable composition described above. <4> The monofunctional monomer (A2) is an N-substituted (meth)acrylamide. <1> ~ <3> An active energy ray curable composition as described in any of the following. <5> <1> ~ <4> A cured product obtained by curing an active energy ray curable composition as described in any of the above. [Examples]

[0106] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0107] <Preparation of Activated Energy Ray Curable Compositions> (Examples 1-6, Comparative Example 1) According to the proportions (parts by weight) in Table 1, a monofunctional monomer (A), a polyfunctional (meth)acrylate (C) with a weight-average molecular weight of 6500 to 40000, a photopolymerization initiator (D), and other monomers (M) were charged into a glass container. After stirring until homogeneous, a mixture of nitrogen and air was supplied to the mixed solution at a rate of 10 mL / min, and dehydration was carried out under reduced pressure at 7 kPa at 50°C for 1 hour to obtain the active energy ray curable compositions of Examples 1 to 6 and Comparative Example 1.

[0108] (Example 7) In Example 1, the vacuum dehydration conditions were changed from "50°C at a pressure of 7kPa for 1 hour" to "50°C at a pressure of 7kPa for 3 hours," but otherwise the procedure was carried out in the same manner as in Example 1 to obtain the active energy ray curable composition of Example 7.

[0109] (Example 8) In Example 1, the vacuum dehydration conditions were changed from "50°C at a pressure of 7kPa for 1 hour" to "20°C at a pressure of 7kPa for 1 hour," but otherwise the procedure was carried out in the same manner as in Example 1 to obtain the active energy ray curable composition of Example 8.

[0110] (Comparative Example 2) According to the proportions (parts by weight) shown in Table 1, monofunctional monomer (A), photopolymerization initiator (D), and other monomers (M) were charged into a glass container and stirred at 20°C under atmospheric pressure for 10 hours to obtain the active energy ray curable composition of Comparative Example 2.

[0111] (Comparative Example 3) In Example 7, the procedure was carried out in the same manner as in Example 7, except that the vacuum dehydration conditions were changed from "50°C at a pressure of 7 kPa for 3 hours" to "60°C under atmospheric pressure conditions with stirring for 10 hours" and the proportions (parts by weight) were as shown in Table 1, to obtain the active energy ray curable composition of Comparative Example 3.

[0112] (Comparative Example 4) In Example 7, the vacuum dehydration conditions were changed from "50°C at a pressure of 7kPa for 3 hours" to "55°C at a pressure of 7kPa for 8 hours," but otherwise the procedure was carried out in the same manner as in Example 7 to obtain the active energy ray curable composition of Comparative Example 4.

[0113] (Comparative Example 5) The procedure was carried out in the same manner as in Example 7, except that "3 hours at 50°C and a pressure of 7 kPa" was replaced with "15 hours under 20°C and atmospheric pressure conditions," to obtain the active energy ray curable composition of Comparative Example 5.

[0114] [Table 1]

[0115] The raw materials used in Table 1 are as follows: (A1-1): Lauryl acrylate [Product name: LA, manufactured by Osaka Organic Chemical Industry Co., Ltd.] (Tg of homopolymer: -30℃) (A1-2): (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate [Product name: MEDOL-10, manufactured by Osaka Organic Chemical Industry Co., Ltd.] (Tg of homopolymer: -7℃) (A1-3): 2-[(butylamino)carbonyl]oxyethyl acrylate [product name: Viscoat #216, manufactured by Osaka Organic Chemical Industry Co., Ltd.] (homopolymer Tg: 0℃) (A1-4): Tetrahydrofurfuryl acrylate [Product name: Viscoat #150, manufactured by Osaka Organic Chemical Industry Co., Ltd.] (Tg of homopolymer: -12℃) (A2-1): N-Acryloylmorpholine [Trade name: ACMO, manufactured by KJ Chemicals] (Tg of homopolymer: 145℃) (A2-2): N,N-dimethylacrylamide [Trade name: DMAA, manufactured by KJ Chemicals] (Tg of homopolymer: 119℃) (A2-3): Isobornyl acrylate [Product name: Light Acrylate IBXA, manufactured by Kyoeisha Chemical Co., Ltd.] (Tg of homopolymer: 97℃) (A2-4): Cyclic trimethylolpropane formal acrylate [Product name: Viscoat #200, manufactured by Osaka Organic Chemical Industry Co., Ltd.] (Tg of homopolymer: 27℃) (C-1): Urethane diacrylate (weight-average molecular weight approximately 18,000) [Product name: UV-3000B, manufactured by Mitsubishi Chemical Corporation] (C-2): Urethane diacrylate (weight-average molecular weight approximately 13,000) [Product name: UV-3300B, manufactured by Mitsubishi Chemical Corporation] (C-3): Urethane diacrylate (weight-average molecular weight approximately 6500) [Product name: UN-6200, manufactured by Negami Kogyo Co., Ltd.] (C-4): Urethane diacrylate (weight-average molecular weight approximately 20,000) [Product name: UN-7700, manufactured by Negami Kogyo Co., Ltd.] (C-5): Urethane diacrylate (weight-average molecular weight approximately 12,500) [Product name: UN-350, manufactured by Negami Kogyo Co., Ltd.] (C-6): Urethane diacrylate (weight-average molecular weight approximately 35,000) [Product name: UF-C051, manufactured by Kyoeisha Chemical Co., Ltd.] (M-1): Reaction product of 6-hexanolide addition polymerization of 2-hydroxyethyl methacrylate and phosphoric anhydride [Product name: KAYAMER PM-21, manufactured by Nippon Kayaku Co., Ltd.] (M-2): Polyethylene glycol diacrylate (weight-average molecular weight approximately 1100) [Product name: NK Ester A-1000, manufactured by Shin Nakamura Chemical Industry Co., Ltd.] (M-3): Polypropylene glycol diacrylate (weight-average molecular weight approximately 800) [Product name: NK Ester APG-700, manufactured by Shin Nakamura Chemical Industry Co., Ltd.] (M-4): Silicone diacrylate (weight-average molecular weight approximately 2500) [Product name: EBECRYL350, manufactured by Daicel Ornex] (D-1): (2,4,6-trimethylbenzoyl)-diphenylphosphine oxide [Trade name: Irgacure TPO, manufactured by IGM Resins BV] (D-2): 2-Methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone [Trade name: Irgacure 907, manufactured by IGM Resins BV] (D-3): Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide [Trade name: Irgacure 819, manufactured by IGM Resins BV] (D-4): 1-Hydroxycyclohexylphenyl ketone [Trade name: Irgacure 184, manufactured by IGM Resins BV]

[0116] Table 1 shows the results of measuring or evaluating the initial viscosity, moisture content, acid value, and coating curability of each active energy ray curable composition obtained in Examples 1-8 and Comparative Examples 1-5, as well as the total light transmittance, elastic modulus, elongation, recovery rate, and storage stability of the cured product, using the following test methods.

[0117] (1) Measurement of initial viscosity Each of the active energy ray-curable compositions obtained in Examples 1-8 and Comparative Examples 1-5 was temperature-controlled at 25°C for 30 minutes, and the initial viscosity (mPa·s) was measured using an E-type viscometer [VISCOMETER TV-25L manufactured by Toki Sangyo Co., Ltd.] under the following conditions. [Measurement conditions] Cone rotor: Standard cone rotor (1°34' × R24) Measurement temperature: 25℃ Measurement range: M Rotation speed: 50 rpm

[0118] (2) Measurement of moisture content (weight %) The moisture content (by weight) of each active energy ray curable composition obtained in Examples 1-8 and Comparative Examples 1-5 was measured in accordance with JIS K0113.

[0119] (3) Measurement of acid value (mgKOH / g) The acid value (mgKOH / g) of each active energy ray curable composition obtained in Examples 1-8 and Comparative Examples 1-5 was measured in accordance with JIS K0070.

[0120] (4) Evaluation of coating film hardening properties Each of the active energy ray-curable compositions obtained in Examples 1-8 and Comparative Examples 1-5 was applied to a surface-treated 100 μm thick PET (polyethylene terephthalate) film [Cosmoshine A4300, manufactured by Toyobo Co., Ltd.] using an applicator to a film thickness of 10 μm. Subsequently, an LED light source ultraviolet irradiation device [model number "FJ100 150×20 385", manufactured by Phoseon Technology Co., Ltd., irradiation wavelength 385 nm] was used to irradiate the film at an intensity of 200 mW / cm² under a nitrogen atmosphere. 2 Exposure was performed using [a specific method / setting]. The exposure dose was 1000 mJ / cm². 2 The curability of the cured coating film was checked by touch immediately after light irradiation and 10 seconds after light irradiation to confirm the presence or absence of tackiness. If tack is present, the irradiation intensity should be 200 mW / cm², as described above. 2 Exposure was performed using (total exposure dose for the first and second exposures: 2000 mJ / cm²). 2 The curability immediately after light irradiation and 10 seconds after light irradiation was checked by touch to confirm the presence or absence of tack. The coating film curability was evaluated according to the following criteria. A coating film curability of 2 or higher is preferable, and 3 is more preferable. In addition, if the coating film curability evaluation was 1, the curability was insufficient, so the subsequent evaluation of the total light transmittance, elastic modulus, elongation, recovery rate, and storage stability of the cured product was not performed. [Evaluation Criteria] 3: Exposure dose 1000 mJ / cm 2 And the tucks disappeared. 2: Total exposure: 2000 mJ / cm² 2 And the tucks disappeared. 1: Total exposure 2000 mJ / cm² 2 But it has pleats.

[0121] (5) Evaluation of the total light transmittance of the cured product Each of the active energy ray-curable compositions obtained in Examples 1-8 and Comparative Examples 1-5 was applied to a surface-treated 100 μm thick PET (polyethylene terephthalate) film [Cosmoshine A4300, manufactured by Toyobo Co., Ltd.] using an applicator to a film thickness of 10 μm. Subsequently, an LED light source ultraviolet irradiation device [model number "FJ100 150×20 385", manufactured by Phoseon Technology Co., Ltd., irradiation wavelength 385 nm] was used to irradiate the film at an intensity of 200 mW / cm² under a nitrogen atmosphere. 2 Samples for evaluation were prepared by exposure. The exposure dose was 2000 mJ / cm². 2 That was the case. The prepared evaluation samples were temperature-controlled at 25°C for 30 minutes, and the total light transmittance (%) was measured using a total light transmittance measuring device [product name "haze-garddual", manufactured by BYK gardner Co., Ltd.] in accordance with JIS K7136:2000. In this invention, it is preferable that the total light transmittance is 90% or higher.

[0122] (6) Evaluation of the elastic modulus and elongation of the cured product <Preparation of test specimens> A PET film [product name: Lumirror S, manufactured by Toray Industries, Inc.] was attached to a glass plate [product name: GLASS PLATE, manufactured by AS ONE Corporation, 200 mm x 200 mm x 5 mm thick], and an active energy ray curable composition was applied using an applicator to achieve a cured film thickness of 100 μm. The mixture was then irradiated with ultraviolet light at a rate of 2000 mJ / cm² under a nitrogen atmosphere using an ultraviolet irradiation device [model number "VPS / I600", manufactured by Fusion UV Systems Co., Ltd.]. 2 Irradiated the film to obtain a PET film coated with a cured product of an active energy ray-curable composition. The PET film coated with the above-mentioned cured material was punched out into a dumbbell shape (size 3) in accordance with JIS K 6251:2017, and then the PET film was peeled off to obtain test specimens for measurement. <Tensile Test> The obtained test specimens were left to stand at 25°C and 50% RH for 5 hours, and then tensile tests were performed using an Autograph [model number "AG-IS" (manufactured by Shimadzu Corporation)] in accordance with JIS K 6251:2017 to measure the modulus of elasticity and elongation. [Measurement conditions] Chuck spacing: 20mm Distance between gauge lines: 20mm Tensile speed: 10 mm / min Next, the growth rate (%) was calculated using the following formula (2). Elongation (%) = (Gauge length at fracture - Gauge length) / (Gauge length) × 100 ... (2) The elastic modulus was analyzed for the portion with a displacement of 0.01 to 0.05 mm. In this invention, the modulus of elasticity is preferably 10 MPa or less, more preferably 5 MPa or less, and even more preferably 2 MPa or less. Furthermore, the elongation is preferably 50% or more, and more preferably 100% or more. In addition, a relationship between elongation and modulus of elasticity {elongation (%) / modulus of elasticity (MPa)} of 120 or more is preferable because it makes the material more easily deformable and provides excellent flexibility.

[0123] (7) Evaluation of the restorability of the cured product <Recovery Rate> The test specimens obtained in the same manner as in "(6) Evaluation of the elastic modulus and elongation of the cured material" were left to stand at 25°C and 50% RH for 5 hours. Then, in accordance with JIS K 6251:2017, they were stretched to 50% elongation using an Autograph [model number "AG-IS" manufactured by Shimadzu Corporation], and the recovery rate was calculated after returning the grips to the 0% position and leaving them to stand for 1 hour. Restoration rate (%) = (Gauge mark distance before test (20 mm)) / (Gauge mark distance after test) × 100 For Comparative Examples 1, 2, and 4, the recovery rate could not be calculated because the test specimens were destroyed. In the present invention, the recovery rate is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0124] (8) Storage stability Each of the active energy ray-curable compositions obtained in Examples 1-8 and Comparative Examples 1-5 was left to stand in a circulating air dryer at 40°C for one month, and then evaluated according to the following evaluation criteria in the same manner as in "(6) Method for evaluating the elongation of the cured product". [Evaluation Criteria] ◎: The growth rate after standing at 40℃ for one month is between 95% and 100% compared to the growth rate before standing. ○: At 40℃, the growth rate after 1 month of standing is 90% or more but less than 95% compared to the growth rate before standing. △: The growth rate after standing at 40℃ for one month is 85% or more but less than 90% compared to the growth rate before standing. ×: The elongation rate after standing at 40°C for one month is less than 85% compared to the elongation rate before standing. [Industrial applicability]

[0125] The active energy ray curable composition of the present invention exhibits excellent flexibility and resilience, as well as superior storage stability, making it useful as a material for various electronic components, stretchable devices, and various optical components, including display components such as flexible displays. In particular, it can be suitably used for bonding and sealing applications of electronic components such as display components and image sensors, and semiconductor packages. It can also be widely used for various coatings, inks (UV printing inks and UV inkjet printing inks, screen printing inks, etc.), and paints.

Claims

1. An active energy ray curable composition comprising a monofunctional monomer (A), a polyfunctional (meth)acrylate (C) having a weight-average molecular weight of 6,500 to 40,000, water, and a photopolymerization initiator (D), wherein the monofunctional monomer (A) comprises a monofunctional monomer (A1) having a homopolymer glass transition temperature of less than 25°C and a monofunctional monomer (A2) having a homopolymer glass transition temperature of 25°C or higher, and based on the total weight of the monofunctional monomer (A) and the polyfunctional (meth)acrylate (C), the content of the monofunctional monomer (A) is 10 to 75% by weight, the content of the polyfunctional (meth)acrylate (C) is 25 to 90% by weight, the content of the photopolymerization initiator (D) is 0.1 to 20% by weight, the water content is 0.005 to 0.5% by weight based on the weight of the active energy ray curable composition, and the inter-crosslinking molecular weight of the cured product is 5,000 to 25,000.

2. The active energy ray curable composition according to claim 1, wherein the acid value of the active energy ray curable composition is 0.01 to 1.5 mg KOH / g.

3. The active energy ray curable composition according to claim 1, wherein the monofunctional monomer (A2) is a monofunctional monomer having a nitrogen atom in its molecule.

4. The active energy ray curable composition according to claim 1, wherein the monofunctional monomer (A2) is an N-substituted (meth)acrylamide.

5. A cured product obtained by curing the active energy ray curable composition according to any one of claims 1 to 4.

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