UV-curable compositions and cured products

Abstract

To provide an ultraviolet-curable composition which has low viscosity and can form a coating film excellent in high heat resistance, low outgassing properties and bending resistance.SOLUTION: An ultraviolet-curable composition contains an N-substituted (meth)acrylamide (A), a bifunctional (meth)acrylate (B) represented by the following general formula (1), a (meth)acrylate (C) having a urethane group, and a photopolymerization initiator (D) containing an acylphosphine oxide compound. CH2=CXCO-O-(R-O)n-COCX=CH2 (1) [where n represents an integer of 2-15; R represents a C2-6 alkylene group (provided that when there are a plurality of R's in one molecule, each R independently represents a C2-6 alkylene group); and each X independently represents a hydrogen atom or a methyl group.]SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to ultraviolet-curable compositions and cured products. [Background technology]

[0002] Organic EL (electroluminescent) light-emitting devices are being applied to lighting, displays, and other applications, and their widespread adoption is expected in the future. In an organic EL light-emitting device, for example, organic EL elements are arranged on a support substrate, these organic EL elements are covered with an inorganic layer called a passivation layer, and the passivation layer is further covered with a encapsulant made of organic resin. It has been proposed to produce encapsulants for organic EL light-emitting devices using an inkjet method. For example, Patent Document 1 discloses the production of encapsulants by an inkjet method using an ink composition containing 75-95 wt.% polyethylene glycol dimethacrylate monomer, 4-10 wt.% pentaerythritol tetraacrylate, and 1-15 wt.% of a spreading modifier having a viscosity in the range of about 14 to about 18 cps at 22°C and a surface tension in the range of about 35 to about 39 dynes / cm at 22°C.

[0003] As mentioned above, organic EL light-emitting devices are used in displays, but in recent years there has been a demand for their application to flexible displays and foldable displays. In particular, for application to foldable displays, bending resistance is necessary due to the characteristic of being repeatedly bent, but the composition described in Patent Document 1 has insufficient bending resistance, which is a problem when considering its application to such displays. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2017-531049 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultraviolet curable composition capable of forming a coating film having low viscosity, high heat resistance, low outgassing property and excellent flexural resistance.

Means for Solving the Problems

[0006] As a result of intensive studies to achieve the above object, the present inventors have reached the present invention. That is, the present invention relates to an N-substituted (meth)acrylamide (A), a bifunctional (meth)acrylate (B) represented by the following general formula (1), a (meth)acrylate (C) having a urethane group, an ultraviolet curable composition containing a photopolymerization initiator (D) containing an acylphosphine oxide compound; and a cured product obtained by curing the ultraviolet curable composition. [[ID=**18**]]CH2=CXCO-O-(R-O) n [[ID=**20**]]-COCX=CH2(1) [n is an integer of 2 or more and 15 or less, R is an alkylene group having 2 or more and 6 or less carbon atoms (however, when there are a plurality of Rs in one molecule, each R is independently an alkylene group having 2 or more and 6 or less carbon atoms), and X is each independently a hydrogen atom or a methyl group.]

Effects of the Invention

[0007] The ultraviolet curable composition of the present invention has low viscosity and can form a coating film excellent in high heat resistance, low outgassing property and flexural resistance.

Modes for Carrying Out the Invention

[0008] As a result of studies to achieve the above problems, the present inventors have reached the present invention. That is, the present invention relates to an N-substituted (meth)acrylamide (A), a bifunctional (meth)acrylate (B) represented by the following general formula (1), a (meth)acrylate (C) having a urethane group, It is an ultraviolet curable composition containing a photoinitiator (D) containing an acylphosphine oxide compound. CH2=CXCO-O-(R-O) n -COCX=CH2(1) [n is an integer of 2 or more and 15 or less, R is an alkylene group having 2 or more and 6 or less carbon atoms (however, when there are a plurality of Rs in one molecule, each R is independently an alkylene group having 2 or more and 6 or less carbon atoms), and X is each independently a hydrogen atom or a methyl group.]

[0009] In the present invention, "(meth)acrylate" means methacrylate or acrylate. In the present invention, "(meth)acrylic" means methacrylic or acrylic.

[0010] In the present invention, N-substituted (meth)acrylamide (A) means that one or two of the hydrogen atoms of the amino group of (meth)acrylamide are substituted with a substituent such as a hydrocarbon group. Examples of N-substituted (meth)acrylamide include N-alkoxyalkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, N-alkoxyalkyl-N-alkyl (meth)acrylamide, N-hydroxyalkyl (meth)acrylamide, and heterocyclic ring-containing (meth)acrylamide in which the nitrogen atom of the (meth)acrylamide group forms a heterocyclic ring.

[0011] Examples of N-alkoxyalkyl (meth)acrylamide include N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-propoxymethyl (meth)acrylamide, N-n-butoxymethyl (meth)acrylamide, and N-isobutoxymethyl (meth)acrylamide. The number of carbon atoms of the N-alkoxyalkyl group of N-alkoxyalkyl (meth)acrylamide is preferably 2 to 10 from the viewpoint of the viscosity of the ultraviolet curable composition.

[0012] Examples of N,N-dialkyl(meth)acrylamides 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 number of carbon atoms in the two alkyl groups of the N,N-dialkyl(meth)acrylamide is preferably 1 to 10 independently from the viewpoint of the viscosity of the UV-curable composition.

[0013] Examples of N-alkoxyalkyl-N-alkyl(meth)acrylamides include Nn-butoxymethyl-N-methyl(meth)acrylamide, N-methyl-N-methoxymethyl(meth)acrylamide, N-methyl-N-ethoxymethyl(meth)acrylamide, N-methyl-N-propoxymethyl(meth)acrylamide, N-methyl-N-butoxymethyl(meth)acrylamide, N-ethyl-N-methoxymethyl(meth)acrylamide, N-ethyl-N-ethoxymethyl(meth)acrylamide, N-ethyl-N-butoxymethyl(meth)acrylamide, N-propyl-N-methoxymethyl(meth)acrylamide, N-propyl-N-ethoxymethyl(meth)acrylamide, N-butyl-N-methoxymethyl(meth)acrylamide, and N-butyl-N-ethoxymethyl(meth)acrylamide. The number of carbon atoms in the N-alkoxyalkyl-N-alkyl(meth)acrylamide is preferably 2 to 10 from the viewpoint of the viscosity of the UV-curable composition, and the number of carbon atoms in the N-alkoxyalkyl-N-alkyl(meth)acrylamide is preferably 1 to 10 from the viewpoint of the viscosity of the UV-curable composition.

[0014] Examples of N-hydroxyalkyl(meth)acrylamides include N-hydroxyethyl(meth)acrylamide. The number of carbon atoms in the N-hydroxyalkyl(meth)acrylamide is preferably 1 to 10 from the viewpoint of the viscosity of the UV-curable composition.

[0015] Examples of heterocyclic (meth)acrylamides in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle include N-(meth)acryloylmorpholine, N-(meth)acryloylthiomorpholine, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, and N-(meth)acryloylpiperidine.

[0016] In the present invention, these N-substituted (meth)acrylamides (A) can be used individually or in combination of two or more. Of these, preferred from the viewpoint of curability are N,N-dialkyl(meth)acrylamide, N-alkoxyalkyl(meth)acrylamide, and heterocyclic (meth)acrylamide in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle. More preferably are N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-(meth)acryloylmorpholine, and Nn-butoxymethyl(meth)acrylamide. Particularly preferred are N,N-dimethylacrylamide, N,N-diethylacrylamide, N-acryloylmorpholine, and Nn-butoxymethylacrylamide.

[0017] The UV-curable composition of the present invention contains a bifunctional (meth)acrylate (B) represented by general formula (1). CH2=CXCO-O-(RO) n -COCX=CH2(1) [In general formula (1), n ​​is an integer between 2 and 15, R is an alkylene group having 2 to 6 carbon atoms (however, if there are multiple R groups in one molecule, each R is independently an alkylene group having 2 to 6 carbon atoms), and X is independently a hydrogen atom or a methyl group.]

[0018] In general formula (1), R represents an alkylene group having 2 to 6 carbon atoms, specifically including ethylene, 1,2-propylene, 1,3-propylene, 1,2-butylene, 1,3-butylene, and 1,4-butylene groups. From the viewpoint of the hardness of the cured product, alkylene groups having 2 to 3 carbon atoms are preferred, and ethylene groups and 1,2-propylene groups are more preferred. n is an integer between 2 and 15, and is preferably an integer between 7 and 15 from the viewpoint of low outgassing and bending resistance.

[0019] Examples of difunctional (meth)acrylates (B) represented by general formula (1) include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polyethylene glycol (n=9) di(meth)acrylate, polyethylene glycol (n=14) di(meth)acrylate, polypropylene glycol (n=7) di(meth)acrylate, and polypropylene glycol (n=12) di(meth)acrylate. Hereinafter, n represents the number of repeating alkylene oxy groups. The same applies hereafter. These two-functional (meth)acrylates (B) can be used individually or in combination of two or more. Among these, from the viewpoint of the hardness of the cured product, a bifunctional acrylate is preferably used, and more preferably dipropylene glycol diacrylate, tripropylene glycol diacrylate, diethylene glycol diacrylate, polytetramethylene glycol diacrylate, polyethylene glycol (n = 9) diacrylate, polyethylene glycol (n = 14) diacrylate, and polypropylene glycol (n = 7) diacrylate polypropylene glycol (n = 12) diacrylate, particularly preferably dipropylene glycol diacrylate, tripropylene glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol (n = 9) diacrylate, polyethylene glycol (n = 14) diacrylate, polypropylene glycol (n = 7) diacrylate, and polypropylene glycol (n = 12) diacrylate, and most preferably dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol (n = 7) diacrylate, and polypropylene glycol (n = 12) diacrylate.

[0020] The ultraviolet curable composition of the present invention contains a (meth)acrylate (C) having a urethane group. The (meth)acrylate (C) having a urethane group is not particularly limited as long as it is a (meth)acrylate having a urethane group. For example, a compound represented by the following general formula (2) having one urethane group and one polymerizable unsaturated double bond each can be mentioned. By using such a (meth)acrylate having a urethane group, the adhesion and stretchability of the obtained cured product tend to be further improved. The (meth)acrylate (C) having a urethane group may be used alone or in combination of two or more. CH2=CR 1 -COO-R 2 -OCONH-R 3 ···(2) (In formula (2), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a divalent hydrocarbon group which may have a substituent, and R 3(This indicates a monovalent hydrocarbon group which may have substituents.)

[0021] In the formula, R 2 Examples of divalent hydrocarbon groups represented by include alkylene groups such as methylene, ethylene, propylene, butylene, and cyclohexylene; arylene groups such as phenylene and naphthalene; and aralkylene groups such as xylylene. Among these, alkylene groups are preferred from the viewpoint of viscosity and bending resistance, methylene and ethylene groups are more preferred, and ethylene groups are even more preferred. 2 The number of carbon atoms in the divalent hydrocarbon group represented is preferably 1 to 9, and more preferably 1 to 6, from the viewpoint of viscosity and bending resistance.

[0022] In the formula, R 3 Examples of monovalent hydrocarbon groups represented by include alkyl groups, cycloalkyl groups, alkenyl groups, aryl groups, alkylaryl groups, or arylalkyl groups. Among these, alkyl groups are preferred from the viewpoint of viscosity and bending resistance. 3 The number of carbon atoms in the monovalent hydrocarbon group represented is preferably 1 to 9, and more preferably 2 to 6, from the viewpoint of viscosity and bending resistance.

[0023] R 2 A divalent hydrocarbon group represented by and R 3 The monovalent hydrocarbon group represented by may have substituents. Substituents are not particularly limited, but examples include halogen atoms, alkoxy groups, carbonyl groups, amino groups, imino groups, cyano groups, azo groups, azi groups, thiol groups, sulfo groups, nitro groups, hydroxyl groups, acyl groups, and aldehyde groups.

[0024] The molecular weight of the (meth)acrylate (C) having a urethane group is preferably 500 or less, and more preferably 300 or less, from the viewpoint of viscosity and bending resistance.

[0025] Specific examples of (meth)acrylate (C) having a urethane group are not particularly limited, but include (methylaminocarbonyl)oxyethylene (meth)acrylate, (ethylaminocarbonyl)oxyethylene (meth)acrylate, (propylaminocarbonyl)oxyethylene (meth)acrylate, (butylaminocarbonyl)oxyethylene (meth)acrylate, (pentylaminocarbonyl)oxyethylene (meth)acrylate, (hexylaminocarbonyl)oxyethylene (meth)acrylate, and urethane (meth)acrylate (such as ETERCURE DR-U250). Of these, the compound represented by general formula (2) is preferred from the viewpoint of viscosity and bending resistance, more preferably (butylaminocarbonyl)oxyethylene (meth)acrylate, and particularly preferably (butylaminocarbonyl)oxyethylene acrylate.

[0026] The UV-curable composition of the present invention contains a photopolymerization initiator (D) containing an acylphosphine oxide compound. Examples of acylphosphine oxide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide. The photopolymerization initiator (D) may further contain compounds other than acylphosphine oxide compounds, for example, at least one selected from the group consisting of benzoin compounds, acetophenone compounds, anthraquinone compounds, ketal compounds, benzophenone compounds, α-aminoalkylphenone compounds, and oxime ester compounds. The benzoin compound may contain at least one selected from the group consisting of benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1-hydroxycyclohexylphenyl ketone. Acetophenone compounds include, for example, at least one selected from the group consisting of acetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methylphenylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one. Anthraquinone compounds include, for example, at least one selected from the group consisting of 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-chloroanthraquinone, and 2-amylanthraquinone. Ketal compounds include, for example, at least one selected from the group consisting of acetophenone dimethyl ketal and benzyl dimethyl ketal. The benzophenone compound contains at least one selected from the group consisting of, for example, benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 4,4'-bismethylaminobenzophenone. The α-aminoalkylphenone compound contains at least one selected from the group consisting of, for example, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopro-butanone-1 and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone].The oxime ester compound contains at least one selected from the group consisting of 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)] and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyl oxime), etc. These photopolymerization initiators (D) can be used individually or in combination of two or more. Of these acylphosphine oxide compounds, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide are preferred from the viewpoint of curability, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is more preferred.

[0027] The content of N-substituted (meth)acrylamide (A) is preferably 20% to 60% by weight, and more preferably 30% to 50% by weight or less, based on the weight of the UV-curable composition, from the viewpoint of curability and low outgassing. The content of the bifunctional (meth)acrylate (B) represented by general formula (1) is preferably 5% to 60% by weight, and more preferably 10% to 50% by weight, based on the weight of the UV-curable composition, from the viewpoint of heat resistance and bending resistance. The content of (meth)acrylate (C) having a urethane group is preferably 1% to 20% by weight, and more preferably 1% to 10% by weight, based on the weight of the UV-curable composition, from the viewpoint of bending resistance and heat resistance. The content of the photopolymerization initiator (D) is preferably 2% to 15% by weight, more preferably 2% to 14% by weight, and even more preferably 3% to 13% by weight, based on the weight of the UV-curable composition, from the viewpoint of curability and viscosity.

[0028] In addition to (A), (B), and (C), the UV-curable composition of the present invention may further contain monofunctional (meth)acrylate (E), bifunctional (meth)acrylate (F), and polyfunctional (meth)acrylate (G).

[0029] Examples of monofunctional (meth)acrylates (E) include monofunctional (meth)acrylates (E1) having a linear or branched alkyl group with 8 to 18 carbon atoms, and monofunctional (meth)acrylates (E2) having a cyclic skeleton, and can also be used to adjust the viscosity of compositions.

[0030] Monofunctional (meth)acrylates (E1) having linear or branched alkyl groups with 8 to 18 carbon atoms include octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate. These (meth)acrylates can be easily produced by direct esterification or transesterification reactions of natural or synthetic alcohols with (meth)acrylic acid or methyl (meth)acrylate, etc. If natural alcohol is used, the alkyl groups will be linear and the number of carbon atoms will be even. If synthetic alcohol is used, for example, if Dovanol (manufactured by Mitsubishi Petrochemical Co., Ltd.) is used, the alkyl groups will be a mixture of linear and branched, and the number of carbon atoms will be a mixture of odd and even. When using Diador (manufactured by Mitsubishi Chemical), alkyl groups become a mixture of straight and branched chains, and only those with an odd number of carbon atoms are produced. Among the monofunctional (meth)acrylates (E1) having linear or branched alkyl groups with 8 to 18 carbon atoms, from the viewpoint of elongation and elastic modulus of the cured product, monofunctional alkyl (meth)acrylates having linear or branched alkyl groups with 8 to 18 carbon atoms are preferred, more preferably monofunctional alkyl (meth)acrylates having linear or branched alkyl groups with 8 to 16 carbon atoms are preferred, and particularly preferred are octyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate. The aforementioned (E1) may be used alone or in combination of two or more types.

[0031] Examples of monofunctional (meth)acrylates (E2) having a cyclic skeleton include isobornyl (meth)acrylate, cyclic trimethylolpropane formal acrylate, phenoxydiethylene glycol acrylate, dicyclopentanyl acrylate, t-butylcyclohexyl acrylate, trimethylcyclohexyl acrylate, and 3-phenoxybenzyl acrylate. The above (E2) may be used individually or in combination of two or more.

[0032] Examples of bifunctional (meth)acrylates (F) other than (B) include alkylenedi(meth)acrylate (F1), di(meth)acrylate (F2) containing polyoxyalkylene groups other than (B), and can raise the glass transition temperature of the cured product.

[0033] Examples of alkylenedi(meth)acrylate (F1) include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, and 1,12-dodecanediol di(meth)acrylate. One of the above (F1) may be used alone, or two or more may be used in combination.

[0034] Examples of di(meth)acrylates (F2) containing polyoxyalkylene groups include 9,9-bis[4-(2-hydroxyethoxy)phenyl]ful orange acrylate and ethoxylated bisphenol A diacrylate. The above (F2) may be used individually or in combination of two or more types.

[0035] The polyfunctional (meth)acrylate (G) is a trifunctional or tetrafunctional (meth)acrylate that is an ester of (meth)acrylic acid with at least one polyhydric alcohol selected from the group consisting of glycerin, trimethylolpropane, pentaerythritol, and their alkylene oxide adducts, and can raise the glass transition temperature of the cured product. Furthermore, the number of moles of the alkylene oxide adduct added is an integer from 1 to 4. If the number of moles added is 5 or more, there is a problem that the viscosity becomes high. The number of carbon atoms in the alkylene oxide of the glycerin alkylene oxide adduct, the trimethylolpropane alkylene oxide adduct, and the pentaerythritol alkylene oxide adduct is preferably 2 to 3, respectively, from the viewpoint of heat resistance. The alkylene oxide is preferably ethylene oxide or propylene oxide.

[0036] In the present invention, examples of polyfunctional (meth)acrylate (G) include glycerin tri(meth)acrylate, ethoxylated glycerin tri(meth)acrylate with an addition number of 1 to 4 moles, propoxylated glycerin tri(meth)acrylate with an addition number of 1 to 4 moles, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate with an addition number of 1 to 4 moles, propoxylated trimethylolpropane tri(meth)acrylate with an addition number of 1 to 4 moles, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate with an addition number of 1 to 4 moles, and propoxylated pentaerythritol tetra(meth)acrylate with an addition number of 1 to 4 moles. These polyfunctional (meth)acrylates (G) may be used individually or in combination of two or more. Of these, preferred from the viewpoint of viscosity are trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and ethoxylated pentaerythritol tetra(meth)acrylate with an addition number of 1 to 4 moles, and more preferably trimethylolpropane triacrylate, pentaerythritol triacrylate, and ethoxylated pentaerythritol tetraacrylate with an addition number of 1 to 4 moles.

[0037] When using polyfunctional (meth)acrylate (G), the content of polyfunctional (meth)acrylate (G) is preferably 1 to 10% by weight, more preferably 1 to 5% by weight, based on the weight of the UV-curable composition, from the viewpoint of heat resistance and bending resistance.

[0038] In addition to (A), (B), and (C), the UV-curable composition of the present invention may further contain α-(allyloxymethyl)acrylate (H) represented by the following general formula (3).

[0039] [ka]

[0040] In formula (3), R 4 R represents a hydrogen atom or an organic group with 1 to 30 carbon atoms. 5 , R 6 , R 7 , R 8 and R 9 Each of these is independently either a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0041] R 5 ~R 9 If the alkyl group is an alkyl group, it may be linear or branched. Specifically, examples include methyl, ethyl, propyl, butyl, amyl, neopentyl, and hexyl groups.

[0042] Examples of α-(allyloxymethyl)acrylate (H) represented by general formula (3) include methyl α-allyloxymethylacrylate and tetrahydrofurfuryl α-allyloxymethylacrylate, which can be used for viscosity adjustment and improvement of bending resistance. The aforementioned (H) may be used alone or in combination of two or more types.

[0043] When using α-(allyloxymethyl)acrylate (H) represented by general formula (3), the content of α-(allyloxymethyl)acrylate (H) represented by general formula (3) is preferably 5% to 30% by weight, and more preferably 10% to 30% by weight, based on the weight of the UV-curable composition, from the viewpoint of low viscosity, bending resistance, and heat resistance.

[0044] The UV-curable composition of the present invention may contain a sensitizer (I). Examples of sensitizers (I) include sensitizers having a thioxanthone skeleton and other sensitizers. Examples of sensitizers having a thioxanthone skeleton include thioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, and Omnipol TX. Other sensitizers besides those containing a thioxanthone skeleton include Anthracure UVS-581. These sensitizers (I) are preferably 2,4-diethylthioxanthone and anthracure UVS-581 from the viewpoint of photosensitivity. Sensitizer (I) may be used alone or in combination of two or more.

[0045] When a sensitizer (I) is used, the content of the sensitizer (I) is preferably 0.2% to 10% by weight, and more preferably 0.5% to 5% by weight, based on the weight of the UV-curable composition, from the viewpoint of curability and photosensitivity.

[0046] The UV-curable composition of the present invention may contain a leveling agent (J). Examples of leveling agents (J) include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, fluorinated surfactants, and silicone surfactants (such as BYK-333 and TEGO TWIN 4200). Of these, fluorinated surfactants and silicone surfactants are preferred from the viewpoint of applicability, and surfactants having an oxyalkyl chain are preferred from the viewpoint of compatibility. Leveling agents (J) may be used alone or in combination of two or more types. When a leveling agent (J) is used, the content of the sensitizer (I) is preferably 0.01% to 3% by weight, and more preferably 0.05% to 1% by weight, based on the weight of the UV-curable composition, from the viewpoint of applicability.

[0047] The UV-curable composition of the present invention may contain various additives to exhibit various functionalities as needed. Specifically, the additive may contain at least one selected from the group consisting of light stabilizers, surface treatment agents, antioxidants, anti-aging agents, crosslinking accelerators, polymerization inhibitors, plasticizers, preservatives, pH adjusters, defoamers, and humectants. When additives are used, the total amount of the additive is, for example, 1.0% by weight or less, 0.5% by weight or less, or 0.4% by weight or less, relative to the total amount of the composition.

[0048] The UV-curable composition of the present invention can be obtained by stirring and mixing the above components in a suitable container such as a glass beaker, can, or plastic cup using a stirring rod, spatula, etc., or by mixing them using a known mixing device (such as a mixing device equipped with a stirring spring like a paddle, a dissolver, a ball mill, and a planetary mixer). The UV-curable composition is preferably liquid at room temperature, and its viscosity at 25°C is preferably 1 mPa·s or more and 40 mPa·s or less. In this case, it can be applied and molded at room temperature by a casting method, an inkjet method, etc. A viscosity of 25 mPa·s or less is more preferable, 20 mPa·s or less is even more preferable, and 15 mPa·s or less is particularly preferable. A viscosity of 5 mPa·s or more is also preferable, and 8 mPa·s or more is even more preferable. For example, a viscosity of 8 mPa·s or more and 25 mPa·s or less is preferable.

[0049] The water content of the composition is preferably 100 ppm or less, more preferably 70 ppm or less, and particularly preferably 50 ppm or less, from the viewpoint of reducing outgassing.

[0050] To obtain a cured product of an ultraviolet-curable composition, the ultraviolet-curable composition is applied to a substrate by a known method, and then cured by irradiation with ultraviolet light. In this invention, ultraviolet light includes ultraviolet rays, electron beams, X-rays, infrared rays, and visible light. The ultraviolet light used for curing the UV-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 ultraviolet light 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. As a light source that emits ultraviolet light, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps and high-power metal halide lamps, etc. (Latest Trends in UV / EB Curing Technology, edited by Radtech Research Group, CMC Publishing, p. 138, 2006) and LEDs can be used. Among these, LEDs consume less power and generate less ozone compared to other light sources, resulting in lower running costs and a lower environmental impact. The amount of ultraviolet light irradiated when photocuring the UV-curable composition of the present invention is preferably 10 to 10,000 mJ / cm² from the viewpoint of the curability of the composition and the flexibility of the cured product. 2 More preferably 20 to 2,000 mJ / cm² 2 That is the case. Heating may be performed during and / or after irradiation with ultraviolet light to accelerate the curing rate of the ultraviolet-curable composition of the present invention. The heating temperature is preferably 30°C to 200°C, more preferably 35°C to 150°C, and particularly preferably 40°C to 120°C.

[0051] Transparent substrates in the form of films, sheets, or plates can be used as substrates to which the UV-curable composition of the present invention is applied. The material of the substrate can be appropriately selected depending on the application, etc. Examples include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic resins such as triacetylcellulose, polycarbonate resin, and methyl methacrylate copolymer, styrene resin, polysulfone resin, polyethersulfone resin, polycarbonate resin, vinyl chloride resin, and polymethacrylimide resin. Inorganic substrates such as glass substrates can also be used in the same manner.

[0052] The UV-curable composition of the present invention can be applied to a substrate using an inkjet method that continuously ejects fine droplets.

[0053] Examples of cured products of the present invention include those obtained by curing an ultraviolet-curable composition of the present invention, which has been applied to the aforementioned substrate, by irradiation with ultraviolet light. The cured product can be used for various coatings, inks (such as UV printing inks and UV inkjet printing inks), encapsulants or paints in light-emitting devices such as organic ELs. [Examples]

[0054] The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

[0055] <Examples 1-16 and Comparative Examples 1-4> According to the proportions (parts by weight) of ingredients in Table 1, N-substituted (meth)acrylamide (A), a bifunctional (meth)acrylate (B) represented by the following general formula (1), a (meth)acrylate having a urethane group (C), a photopolymerization initiator (D) containing an acylphosphine oxide compound, and optionally a monofunctional (meth)acrylate (E), a bifunctional (meth)acrylate (F), a polyfunctional (meth)acrylate (G), an α-(allyloxymethyl)acrylate (H) represented by the general formula (3), a sensitizer (I), and a leveling agent (J) were charged into a glass container, stirred until homogeneous, to obtain the UV-curable compositions of Examples 1 to 16 and Comparative Examples 1 to 4.

[0056] [Table 1]

[0057] The details of the raw materials represented by the symbols in Table 1 are as follows: (A-1): N-Acryloylmorpholine [ACMO: Manufactured by KJ Chemicals Co., Ltd.] (A-2): N,N-dimethylacrylamide [DMAA: Manufactured by KJ Chemicals Co., Ltd.] (A-3): N,N-Diethylacrylamide [DEAA: Manufactured by KJ Chemicals Co., Ltd.] (A-4): Nn-Butoxymethylacrylamide [NBMA: Manufactured by MCC Unitech Co., Ltd.] (A-5): N-hydroxyethylacrylamide [HEAA: Manufactured by KJ Chemicals Co., Ltd.] (A-6): N,N-dimethylaminopropylacrylamide [DMAPAA: Manufactured by KJ Chemicals Co., Ltd.] (B-1): Dipropylene glycol diacrylate [NK ester APG-100: manufactured by Shin Nakamura Kogyo Co., Ltd., general formula (1), n=2] (B-2): Tripropylene glycol diacrylate [Etermer EM223: manufactured by Changxing Materials Co., Ltd., in general formula (1), n=3] (B-3): Diethylene glycol diacrylate [Funkryl FA-222A: manufactured by Hitachi Chemical Co., Ltd., in general formula (1), n=2] (B-4): Polypropylene glycol diacrylate [APG-400: Manufactured by Shin-Nakamura Chemical Co., Ltd., in general formula (1), n=7] (B-5): Polypropylene glycol diacrylate [APG-700: Manufactured by Shin-Nakamura Chemical Co., Ltd., in general formula (1), n=12] (B-6): Polytetramethylene glycol diacrylate [A-PTMG-65: Manufactured by Shin-Nakamura Chemical Co., Ltd., in general formula (1), n=9] (C-1): (Butylaminocarbonyl)oxyethylene acrylate [Product name "Viscote 216", manufactured by Osaka Organic Co., Ltd.] (C-2): Urethane acrylate [ETERCURE DR-U250: Manufactured by Changxing Materials Co., Ltd.] (D-1): Irgacure 819 [Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: manufactured by Ciba Specialty Chemicals Co., Ltd.] (D-2): Irgacure TPO [(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: manufactured by Ciba Specialty Chemicals Co., Ltd.] (E1-1): Isodecyl acrylate [Product name "IDAA", manufactured by Osaka Organic Chemical Industry Co., Ltd.] (E1-2): Lauryl acrylate [Trade name "LA", manufactured by Osaka Organic Chemical Industry Co., Ltd.] (E1-3): Stearyl acrylate [Trade name "STA", manufactured by Osaka Organic Chemical Industry Co., Ltd.] (E2-1): Isobornyl acrylate [Light acrylate IB-XA: Manufactured by Kyoeisha Chemical Co., Ltd.] (E2-2): Phenoxydiethylene glycol acrylate [A-LEN-10: Manufactured by Shin-Nakamura Chemical Co., Ltd.] (F1-1): 1,9-nonanediol diacrylate [A-NOD-N: Manufactured by Shin-Nakamura Chemical Co., Ltd.] (F1-2): 1,10-Decanediol diacrylate [A-DOD-N: Manufactured by Shin-Nakamura Chemical Co., Ltd.] (G-1): Trimethylolpropane triacrylate [A-TMPT: Manufactured by Shin-Nakamura Chemical Co., Ltd.] (H-1): α-Allyloxymethylacrylate [Product name "AOMA", manufactured by Nippon Shokubai Co., Ltd.] (R 4 is a methyl group, R 5 , R 6 , R 7 , R 8 and R 9 (Hydrogen atom) (I-1): 2,4-Diethylthioxanthone [KayaCure DETX-S: Manufactured by Nippon Kayaku Co., Ltd.] (I-2): Anthracure UVS-581 [Sensitizer: Manufactured by Kawasaki Chemical Co., Ltd.] (I-3): Omnipol TX [Sensitizer: iGM Corporation] (J-1): BYK-333 [Silicone surfactant: Manufactured by Bic Chemie Japan Co., Ltd.] (J-2): TEGO TWIN 4200 [Silicone surfactant: Manufactured by Evonik]

[0058] Table 1 shows the results of measuring or evaluating the viscosity of the UV-curable compositions of Examples 1 to 16 and Comparative Examples 1 to 4, as well as the coating curability, bending resistance, low outgassing, and heat resistance (glass transition temperature) of their cured products, using the following test methods. [Viscosity evaluation] The viscosity of the UV-curable composition was measured using an E-type viscometer (TV-25, manufactured by Toki Sangyo Co., Ltd.) under conditions of a rotation speed of 50 rpm and a temperature of 25°C. A viscosity of 25 mPa·s or less is considered low viscosity and is preferable.

[0059] (1) Evaluation of coating film hardening properties Each UV-curable composition obtained in Examples 1-16 and Comparative Examples 1-4 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 20 μm. Subsequently, an LED light source UV 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. 2Exposure was performed using [a specific method / equipment]. The exposure dose was 2000 mJ / cm². 2 That was the case. The curability of the cured coating immediately after light irradiation was evaluated by touch, specifically by the presence or absence of tackiness. <Evaluation Criteria> ○: No pleats ×: With pleats

[0060] (2) Evaluation of bending resistance <Preparation of test specimens for evaluation> Each UV-curable composition obtained in Examples 1-11 and Comparative Examples 1-4 was applied to a 10cm x 10cm square polyimide film using an applicator to a thickness of 10μm. Subsequently, an LED light source UV irradiation device [model number "FJ100 150×20 385", manufactured by Phoseon Technology Co., Ltd., irradiation wavelength 385nm] was used to irradiate the film at an intensity of 200mW / cm² under a nitrogen atmosphere. 2 Exposure was performed using [a specific method / equipment]. The exposure dose was 2000 mJ / cm². 2 Therefore, test specimens were prepared to evaluate bending resistance.

[0061] <Evaluation of bending resistance> The obtained cured material was subjected to a bending test at a radius of curvature of 2 mm using a surface unloaded U-shaped expansion and contraction test fixture DMX-FS manufactured by Yuasa Systems Equipment, and the number of bending cycles until the coating of the cured material peeled off from the polyimide film or the coating cracked (whichever came first) was measured. <Evaluation Criteria> A: More than 10,000 times of folding B: Number of folds: 5,000 to less than 10,000 C: Number of folds: 1000 to less than 5000 D: Less than 1000 folds

[0062] (3) Evaluation of heat resistance (glass transition temperature 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 ultraviolet-curable composition was applied using an applicator to achieve a cured film thickness of 100 μm. An ultraviolet irradiation device [model number "VPS / I600", manufactured by Fusion UV Systems Co., Ltd.] was used to irradiate the surface with ultraviolet light at a rate of 1000 mJ / cm² under a nitrogen atmosphere. 2 The film was irradiated to obtain a PET film coated with a cured product of an ultraviolet-curable composition.

[0063] <Evaluation of heat resistance (glass transition temperature of cured material)> The obtained test specimens were shaped using a cutter to form specimens with a width of 5 mm and a length of 50 mm. The Tg was measured using the DMA method in tensile mode at 10 Hz with a dynamic viscoelasticity analyzer (DMA) [model number "Rheogel-E4000", manufactured by UBM Co., Ltd.]. The higher the glass transition temperature, the better the heat resistance. A glass transition temperature of 80°C or higher indicates good heat resistance.

[0064] (4) Outgassing <Preparation of outgassing evaluation test samples> Each UV-curable composition obtained in Examples 1-11 and Comparative Examples 1-4 was coated onto a glass plate to a thickness of 10 μm, and then exposed to light under a nitrogen atmosphere using an LED-UV irradiator manufactured by CCS Corporation, with a peak wavelength of 395 nm and an intensity of approximately 500 mW / cm². 2 After curing by light irradiation under these conditions, approximately 50 mg of the cured material was placed into a 22 mL headspace vial, and the vial was sealed. <Outgassing Assessment> Next, the cured material sealed in the vial was heated at 110°C for 30 minutes, and the outgassed gaseous portion in the vial was introduced into a gas chromatograph using the headspace method for analysis. Based on the peak area of ​​the resulting gas chromatogram, the concentration of outgassed material from the cured material was determined. The measurement conditions at this time are as follows:

[0065] Equipment: “GC-2010 Plus” manufactured by Shimadzu Corporation Column: Zebron ZB-5 0.25mm x 30m Column temperature: 40~320℃ (20℃ / min) Oven temperature: 110℃ Carrier gas: Helium Inlet pressure: 90 kPas Total flow rate: 21.3mL / min Injection volume: 0.06mL

[0066] The outgassing concentration was calculated by dividing the sum of all peak areas by the weight of the cured material and then dividing that value by 1000. The outgassing concentration is preferably less than 50 nV·s / mg, and more preferably less than 30 nV·s / mg. <Evaluation Criteria> A: Less than 30 nV·s / mg B: 30 to less than 40 nV·s / mg C: 40 to less than 50 nV·s / mg D: 50nV·s / mg or more

[0067] As shown in Table 1, the UV-curable compositions of Examples 1 to 16 of the present invention had low viscosity, and the cured products formed coatings with excellent coating curability, heat resistance, low outgassing, and bending resistance. On the other hand, the cured product of the UV-curable composition of Comparative Example 1 had poor curability and bending resistance, and exhibited significant outgassing. The cured products of the UV-curable compositions of Comparative Examples 2 and 3 also had poor bending resistance and exhibited significant outgassing. The UV-curable composition of Comparative Example 4 had high viscosity, and its cured product had poor bending resistance and heat resistance. [Industrial applicability]

[0068] The UV-curable composition of the present invention has low viscosity and good curability upon UV irradiation. Its cured product exhibits excellent heat resistance (glass transition temperature of the cured product), low outgassing, and bending resistance, and is suitable for high-speed printing. Therefore, it can be suitably used as a encapsulant in light-emitting devices such as organic ELs. Furthermore, it can be suitably used as a material for various coatings, inks (UV printing inks and UV inkjet printing inks, etc.), or paints.

Claims

1. N-substituted (meth)acrylamide (A) and A difunctional (meth)acrylate (B) represented by the following general formula (1), (Meth)acrylate (C) having a urethane group, A UV-curable composition containing a photopolymerization initiator (D) containing an acylphosphine oxide compound, An ultraviolet-curable composition in which the (meth)acrylate (C) having a urethane group is a (meth)acrylate having a urethane group with a molecular weight of 300 or less. CH ２ =CXCO-O-(R-O) ｎ -COCX=CH ２ (1) [In general formula (1), n ​​is an integer between 2 and 15, R is an alkylene group having 2 to 6 carbon atoms (however, if there are multiple R groups in one molecule, each R is independently an alkylene group having 2 to 6 carbon atoms), and X is independently a hydrogen atom or a methyl group.]

2. The ultraviolet-curable composition according to claim 1, wherein the N-substituted (meth)acrylamide (A) is at least one compound selected from the group consisting of N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-(meth)acryloylmorpholine, N-n-butoxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N,N-dimethylaminopropyl(meth)acrylamide.

3. The ultraviolet-curable composition according to claim 1 or 2, wherein the bifunctional (meth)acrylate (B) is an integer in general formula (1) in which n is 7 or more and 15 or less.

4. The UV-curable composition according to claim 1 or 2, further comprising a monofunctional (meth)acrylate (E1) having a linear or branched alkyl group having 8 to 18 carbon atoms.

5. The UV-curable composition according to claim 1 or 2, wherein, based on the weight of the UV-curable composition, the content of the N-substituted (meth)acrylamide (A) is 20% to 60% by weight, the content of the bifunctional (meth)acrylate (B) is 5% to 60% by weight, the content of the (meth)acrylate (C) having a urethane group is 1% to 20% by weight, and the content of the photopolymerization initiator (D) is 2% to 15% by weight.

6. A cured product obtained by curing the ultraviolet-curable composition according to claim 1 or 2.

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