Ink composition for inkjet printing

Abstract

The present invention addresses the problem of providing an actinic-ray-curable ink composition for inkjet printing which has high adhesiveness to adherends and high stretchability, the ink composition being capable of forming ink films that are odorless and are less apt to be tacky. The ink composition for inkjet printing comprises a polymerizable component (A) represented by structural formula (X), a monofunctional polymerizable component (B) comprising a (meth)acrylamide compound and / or an N-vinyl compound, and a polyfunctional polymerizable component (C) comprising an amine-modified oligomer and a polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less, wherein the weight ratio of the polymerizable component (A) content to the monofunctional polymerizable component (B) content, (A) / (B), is in the range of 0.2-2.0 and the proportion of the polyfunctional polymerizable component (C) to the sum of all the polymerizable components is less than 18 mass%.

Description

Ink composition for inkjet printing

[0001] The present invention relates to an ink composition for ink-jet printing.

[0002] Active energy ray-curable ink compositions that can be cured by irradiation with active energy rays such as ultraviolet rays or electron beams are known. Active energy ray-curable ink compositions can be made solvent-free (or contain low amounts of solvent) and have fast drying properties, so they can be printed on a variety of printing substrates. In other words, even when an active energy ray-curable ink composition is printed on a printing substrate with low absorbency, effects such as preventing ink bleeding can be obtained.

[0003] It is also known that an actinic energy ray-curable ink composition is used as an inkjet printing ink composition. Inkjet printing ink compositions are generally required to have low viscosity. For example, Patent Document 1 discloses an ultraviolet-curable inkjet ink composition containing a (meth)acrylate compound having a vinyl group and a polymerizable compound having a ring structure, and claims that the ink composition has low viscosity and high adhesion to a printing substrate.

[0004] Furthermore, Patent Document 2 discloses an ultraviolet-curable inkjet ink composition containing a (meth)acrylate compound having a dioxolane structure and a polyfunctional monomer, and claims that the resulting cured printed film has low tack and flexibility, thereby suppressing cracking of the cured printed film even when printed on a flexible substrate. Patent Document 3 discloses an actinic ray-curable ink containing a (meth)acrylate compound having a dioxolane structure, and claims that it has high adhesion to various substrates. Furthermore, Patent Document 4 discloses an inkjet ink composition containing N-vinyloxazolidinone, a monomer having an alicyclic structure, and a monomer having a heterocyclic structure, and claims that it has good jetting properties and curing properties and suppresses stickiness of the cured coating film.

[0005] JP 2012-193260 A JP 2018-24810 A JP 2019-2010 A International Publication No. 2020 / 179155

[0006] As described above, proposals have been made to improve various physical properties of actinic energy ray-curable ink compositions for inkjet printing. First, in order to obtain a cured printed film with high adhesion to the printing substrate and high extensibility, it is generally effective to increase the content ratio of monofunctional monomers (i.e., decrease the content ratio of polyfunctional monomers). However, if the content ratio of monofunctional monomers is increased, the ink coating film tends to emit an odor and the ink coating film tends to become tacky.

[0007]

[0009] Therefore, the present invention provides an ink composition for inkjet printing that has high adhesion and spreadability to a substrate to be printed, and that produces an ink film that is odorless and less likely to become tacky. More preferably, the present invention provides an ink composition that produces an ink film that has high solvent resistance (including alcohol resistance). The present inventors have discovered that an ink composition for inkjet printing that contains a combination of compounds having specific structures as monofunctional polymerizable components can solve the above-mentioned problems.

[0008] That is, the present invention relates to the following ink composition for inkjet printing: [1] An ink composition for inkjet printing comprising a polymerizable component (A) represented by the following structural formula (X), a monofunctional polymerizable component (B) consisting of a (meth)acrylamide compound and / or an N-vinyl compound, and a polyfunctional polymerizable component (C) containing an amine-modified oligomer and a polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less, wherein the weight ratio ((A) / (B)) of the polymerizable component (A) to the monofunctional polymerizable component (B) is in the range of 0.2 to 2.0, and the content of the polyfunctional polymerizable component (C) with respect to the total amount of all polymerizable components is less than 18% by mass. [R in structural formula (X)] １ and R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or a phenyl group, or R １ and R ２ may be bonded to each other to form a cycloalkyl having 3 to 9 carbon atoms; R ３ , R ４ and R ５each independently represents a hydrogen atom or an alkyl group, R ６ represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 5.

[0009] The present invention also relates to the following ink compositions for inkjet printing: [2] The ink composition for inkjet printing according to [1] above, wherein the content of the polymerizable component (A) relative to the ink composition for inkjet printing is 5 to 30% by mass. [3] The ink composition for inkjet printing according to [1] or [2] above, wherein the content of the amine-modified oligomer relative to the ink composition for inkjet printing is 0.5 to 10% by mass. [4] The ink composition for inkjet printing according to any one of [1] to [3] above, wherein the content of a monofunctional (meth)acrylate monomer having a glass transition temperature of 10°C or less relative to the total amount of all polymerizable components is 30% by mass or more. [5] The ink composition for inkjet printing according to any one of [1] to [4] above, wherein the ink composition for inkjet printing contains a photopolymerization initiator including phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide in an amount of 3 to 10% by mass relative to the ink composition for inkjet printing.

[0010] The ink composition for ink-jet printing of the present invention can suppress the occurrence of odor and tackiness in the cured coating film, and can also sufficiently improve other coating film properties.

[0011] [1. Composition of Ink Composition for Ink Jet Printing] The ink composition for ink jet printing of the present invention contains a polymerizable component (A) represented by structural formula (X), a monofunctional polymerizable component (B) consisting of an acrylamide compound and / or an N-vinyl compound, and a polyfunctional polymerizable component (C). The ink composition for ink jet printing of the present invention may also contain a monofunctional polymerizable component (D) other than the polymerizable components (A) and (B).

[0012] The ink composition for inkjet printing of the present invention may contain, in addition to the polymerizable component, a photopolymerization initiator, a sensitizer, a polymerization inhibitor, and the like; may further contain a colorant such as a pigment, a pigment dispersant, and the like; and may further contain, as optional additives, a surfactant, and the like.

[0013] [1-1. Polymerizable Component (A)] The polymerizable component (A) is a compound represented by structural formula (X), which is a monofunctional polymerizable compound (monofunctional (meth)acrylate compound) having a dioxolane structure.

[0014] Substituent R in structural formula (X) １ and R ２ are each independently a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or a phenyl group. The alkyl group having 1 to 18 carbon atoms may have a linear, branched, or cyclic structure. １ and R ２ may be bonded to each other to form a cyclic alkyl (for example, a cyclohexyl ring, a cyclopentyl ring, etc.). １ and R ２ are preferably a hydrogen atom or an alkyl group, or are bonded to each other to form a cyclic alkyl group; more preferably an alkyl group; and even more preferably a methyl group or an ethyl group.

[0015] Substituent R in structural formula (X) ３ , R ４ and R ５ are each independently a hydrogen atom or an alkyl group, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom.

[0016] Substituent R in structural formula (X) ６ represents a hydrogen atom or an alkyl group; preferably a hydrogen atom or a methyl group; more preferably a hydrogen atom.

[0017] In structural formula (X), n represents 1 to 5; preferably 1 to 3; and more preferably 1.

[0018] Examples of the compound represented by structural formula (X) include, but are not limited to, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-isobutyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (cyclohexanespiro-2-(1,3-dioxolan-4-yl))methyl (meth)acrylate, etc. Among the compounds represented by structural formula (X), (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate is preferred from the viewpoints of low viscosity and extremely little odor.

[0019] The polymerizable component (A) may be composed of only one compound represented by structural formula (X), or may be a combination of two or more compounds. The content of the polymerizable component (A) is preferably 5% by mass or more, and more preferably 10% by mass or more, relative to the ink composition; and is preferably 30% by mass or less, and more preferably 25% by mass or less.

[0020] Cured products of actinic ray-curable inks containing a large amount of monofunctional monomers tend to produce odors and tackiness. On the other hand, although the compound represented by structural formula (X) is a monofunctional monomer, it is less likely to produce odors or tackiness when actinic ray-curable inks containing it are cured. Furthermore, the compound represented by structural formula (X) can enhance the actinic ray curability of the ink composition compared to other monofunctional monomers.

[0021] [1-2. Monofunctional Polymerizable Component (B)] The monofunctional polymerizable component (B) comprises a (meth)acrylamide compound and / or an N-vinyl compound.

[0022] The (meth)acrylamide compound may be any of N-unsubstituted (meth)acrylamide, N-1-substituted (meth)acrylamide, and N-2-substituted (meth)acrylamide. The substituent on the N of the (meth)acrylamide may be an alkyl group (e.g., a C1-C8 alkyl group) which may have a substituent, and two substituents on the N may be bonded to each other to form a ring. The molecular weight of the (meth)acrylamide compound may be 2,000 or less.

[0023] Examples of the (meth)acrylamide compound include (meth)acrylamide; N-alkyl(meth)acrylamides including N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N-octyl(meth)acrylamide; N-methoxymethyl(meth)acrylamide, N-methylol(meth)acrylamide, diacetone(meth)acrylamide, N-hydroxymethyl(meth)acryldiamide, N-hydroxyethyl(meth)acrylamide, and diacetone acrylamide; and other N-substituted (meth)acrylamides. N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide, (meth)acryloylmorpholine, N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethylaminopropyl(meth)acrylamide, N-disubstituted (meth)acrylamides such as N,N-di(2-hydroxyethyl)(meth)acrylamide, N,N-di(3-hydroxypropyl)(meth)acrylamide, and N,N-di(4-hydroxybutyl)(meth)acrylamide, etc. A preferred example of the (meth)acrylamide compound is acryloylmorpholine (ACMO).

[0024] The N-vinyl compound is a compound in which a vinyl group is bonded to the nitrogen atom of an amine or amide. The N-vinyl compound is preferably a compound in which a vinyl group is bonded to the nitrogen atom of a cyclic amine or cyclic amide. The molecular weight of the N-vinyl compound is preferably 2000 or less.

[0025] Specific examples of the N-vinyl compound include N-vinyl-2-caprolactam, N-vinylpyrrolidone, N-vinylimidazole, N-vinylcarbazole, N-vinylmorpholine, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinylformamide, and N-vinyl-5-methyl-2-oxazolidinone.

[0026] The content weight ratio ((A) / (B)) of the polymerizable component (A) to the monofunctional polymerizable component (B) is 0.2 or more, preferably 0.5 or more, and more preferably 0.7 or more; and on the other hand, it is 2.0 or less, preferably 1.7 or less, and more preferably 1.4 or less. By setting the content weight ratio ((A) / (B)) to a certain level or more, the flexibility and stretchability of the ink coating film (cured coating film) can be improved. Furthermore, by setting the content weight ratio ((A) / (B)) to a certain level or less, the odor of the ink composition can be suppressed and the tackiness of the ink coating film (cured coating film) can also be reduced.

[0027] [1-3. Polyfunctional polymerizable component (C)] The polyfunctional polymerizable component (C) contains an amine-modified oligomer and a polyfunctional (meth)acrylate monomer having a molecular weight of not more than 500. The polyfunctional polymerizable component (C) may also contain other polyfunctional polymerizable compounds.

[0028] [1-3-1. Amine-Modified Oligomer] Amine-modified oligomers are reactive oligomers containing two or more amino groups and functional groups that crosslink or polymerize upon irradiation with active energy rays. They are also sometimes referred to as reactive amine coinitiators, reactive amine synergists, acrylate-modified amine synergists, amine acrylates, etc. An oligomer is a component that polymerizes ethylenically unsaturated bonds within the molecule to achieve a high molecular weight. Because oligomers are relatively high molecular weight components before polymerization, they can impart appropriate viscosity and elasticity to ink compositions. Furthermore, oligomers have relatively high polarity, which can impart adhesion to non-absorbent printing substrates to the cured ink composition. Furthermore, amine-modified oligomers can significantly enhance curability.

[0029] There are no particular restrictions on the viscosity of the amine-modified oligomer, but a viscosity of 2000 cps or less at 25° C. is particularly preferred in order to keep the viscosity of the entire photocurable ink composition for inkjet printing within an appropriate range.

[0030] Amine-modified oligomers are also commercially available. Examples of commercially available amine-modified oligomers include CN371, CN373, CN383, CN386, CN501, CN550, and CN551 manufactured by Sartomer; EBECRYL80 and EBECRYL7100 manufactured by Daicel Allnex; GENOMER5142, GENOMER5161, and GENOMER5275 manufactured by RAHN; Miramer AS2010 and Miramer AS5142 manufactured by Miwon; and Etercure 641, Etercure 6410, Etercure 6411, Etercure 6412, Etercure 6413, Etercure 6414 manufactured by Changxing Chemical Co., Ltd. Examples of preferred amine-modified oligomers include Etercure 6417, Etercure 6420, Etercure 6422, Etercure 6423, Etercure 6425, Etercure 6430, Etercure 645, and Etercure 647. Preferred examples of the amine-modified oligomer are acrylated amine compounds such as CN371, CN373, CN383, and CN386 (manufactured by Sartomer), and more preferred are CN371, CN386 (manufactured by Sartomer) and EBECRYL80 (manufactured by Daicel Allnex Corporation), which have two or more photopolymerizable functional groups in the molecule.

[0031] [1-3-2. Polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less] The polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less is a compound having two or more polymerization-reactive (meth)acryloyl groups. The polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less preferably has a molecular weight of 400 or less, and more preferably a molecular weight of 300 or less.

[0032] Specific examples of polyfunctional (meth)acrylate monomers having two (meth)acryloyl groups include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and butylene glycol di(meth)acrylate. , pentyl glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxypivalyl hydroxypivalate di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,2-hexanediol di(meth)acrylate, 1,5-hexanediol di(meth)acrylate, 2,5-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,2-octanediol di(meth)acrylate , 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,2-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,2-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,2-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,2-hexadecanediol di(meth)acrylate, 2-methyl-2,4-pentanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-2-propyl-1,3-propanediol di(meth)acrylate, 2,4-dimethyl-2,4-pentanediol di(meth)acrylate, 2,2-diethyl-1,3-propanediol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, dimethylol octane di(meth)acrylate, 2-ethyl-1,3-hexanediol di(meth)acrylate, 2,5-dimethyl-2,5-hexanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 2,4-diethyl-1,5-pentanediol di(meth)acrylate, tricyclodecanedimethylol di(meth)acrylate, tricyclodecanedimethylol dicaprolactonate di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, etc.

[0033] Specific examples of polyfunctional (meth)acrylate monomers having three or more (meth)acryloyl groups include glycerin tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolhexane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxy tri(meth)acrylate; and 3EO (ethylene oxide) modified products thereof.

[0034] [1-3-3. Other Polyfunctional Polymerizable Compounds] The polyfunctional polymerizable component (C) may contain other polyfunctional polymerizable compounds in addition to the amine-modified oligomer and the polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less; however, the ratio of other polyfunctional polymerizable compounds in the polyfunctional polymerizable component (C) is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0035] Examples of other polyfunctional polymerizable compounds include polyfunctional (meth)acrylate monomers having a molecular weight of more than 500. However, polyfunctional (meth)acrylate monomers having a molecular weight of more than 500 may increase the viscosity of the ink composition or reduce the alcohol resistance of the cured coating film. Therefore, the proportion of polyfunctional (meth)acrylate monomers having a molecular weight of more than 500 in the polyfunctional polymerizable component (C) is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0036] The content of the polyfunctional polymerizable component (C) relative to the total amount of all polymerizable components contained in the ink composition is less than 18% by mass and preferably 16% by mass or less. By setting the content of the polyfunctional polymerizable component (C) to a certain level or less, the flexibility of the ink coating film (cured film) can be improved, and its bendability and stretchability can be increased. On the other hand, the content of the polyfunctional polymerizable component (C) relative to the total amount of all polymerizable components contained in the ink composition is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and even more preferably 9% by mass or more.

[0037] Furthermore, the content of the amine-modified oligomer constituting the polyfunctional polymerizable component (C) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, relative to the ink composition; on the other hand, it is preferably 10% by mass or less, and more preferably 8% by mass or less. By setting the content of the amine-modified oligomer to a certain level or more, it is possible to improve the curability of the ink composition, and by setting the content of the amine-modified oligomer to a certain level or less, it is possible to suppress an increase in the viscosity of the ink composition.

[0038] [1-4. Other Monofunctional Polymerizable Component (D)] The ink composition of the present invention contains component (A) and component (B) as monofunctional polymerizable components, but may further contain another monofunctional polymerizable component (D). The monofunctional polymerizable component (D) is preferably an ethylenically unsaturated monomer. Furthermore, the molecular weight of the monofunctional polymerizable component (D) is preferably 2000 or less.

[0039] The monofunctional polymerizable component (D) may be an unsaturated carboxylic acid compound, an alkyl (meth)acrylate compound, a hydroxyl group-containing (meth)acrylate compound, a halogen-containing (meth)acrylate compound, an ether group-containing (meth)acrylate compound, a carboxyl group-containing (meth)acrylate compound, other (meth)acrylate compounds, a styrene compound, an arylate compound, or other compounds having one ethylenically unsaturated bond.

[0040] Examples of the unsaturated carboxylic acid compound as the monofunctional polymerizable component (D) include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, fumaric acid, and maleic acid, salts thereof, and acid anhydrides thereof.

[0041] Examples of alkyl(meth)acrylate compounds as the monofunctional polymerizable component (D) include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, i-butyl(meth)acrylate, t-butyl acrylate, amyl(meth)acrylate, isoamyl(meth)acrylate, hexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, octyl(meth)acrylate, decyl(meth)acrylate, dodecyl(meth)acrylate, isooctyl(meth)acrylate, lauryl(meth)acrylate, stearyl(meth)acrylate, and isostearyl(meth)acrylate. acrylate, isodecyl (meth)acrylate, isomyristyl (meth)acrylate, octadecyl (meth)acrylate, dicyclopentanyl (meth)acrylate, tridecyl (meth)acrylate, nonyl (meth)acrylate, hexadecyl (meth)acrylate, myristyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 1-adamantyl (meth)acrylate, 3,5,5-trimethylcyclohexyl acrylate, 4-t-butylcyclohexyl (meth)acrylate, and the like.

[0042] Examples of the hydroxyl group-containing (meth)acrylate compound as the monofunctional polymerizable component (D) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, 2-hydroxy-3-methoxypropyl (meth)acrylate, 2-hydroxy-3-butoxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, Examples of the alkylene glycol-modified (meth)acrylate include (poly)alkylene glycol-modified (meth)acrylates such as polypropylene glycol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate, glycerin mono(meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-allyloxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-ethylhexyl EO-modified (meth)acrylate, o-phenylphenol EO-modified acrylate, p-cumylphenol EO-modified (meth)acrylate, and nonylphenol EO-modified (meth)acrylate.

[0043] Examples of the halogen-containing (meth)acrylate compound as the monofunctional polymerizable component (D) include trifluoromethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H-hexafluoroisopropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-heptadecafluorodecyl (meth)acrylate, 2,6-dibromo-4-butylphenyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, and 2,4,6-tribromophenol 3EO (ethylene oxide) adduct (meth)acrylate.

[0044] Examples of the ether group-containing (meth)acrylate compound as the monofunctional polymerizable component (D) include 1,3-butylene glycol methyl ether (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, and 2-ethylhexyl carbitol (meth)acrylate. acrylate, tetrahydrofurfuryl (meth)acrylate, cresyl polyethylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, p-nonylphenoxyethyl (meth)acrylate, p-nonylphenoxypolyethylene glycol (meth)acrylate, glycidyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxy-polyethylene glycol (meth)acrylate, hexaethylene glycol monophenyl ether mono(meth)acrylate, diethylene glycol monobutyl ether ether acrylate, dipropylene glycol monomethyl ether (meth)acrylate, 3-methoxybutyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate (number of EO repeating units: 400, 700, etc.), 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl acrylate, ethoxyethyl Acrylates, ethoxyethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, alkoxylated 2-phenoxyethyl (meth)acrylate (ethoxylated 2-phenoxyethyl (meth)acrylate, propoxylated 2-phenoxyethyl (meth)acrylate, etc.), alkoxylated nonylphenyl (meth)acrylate (ethoxylated (4) nonylphenol acrylate, etc.), 2-phenoxyethyl (meth)acrylate, paracumylphenoxyethylene glycol (meth)acrylate, methylphenoxyethyl acrylate,Examples of the alkoxy and / or phenoxy (meth)acrylates include ethoxylated succinic acid (meth)acrylate, ethoxylated tribromophenyl acrylate, and ethoxylated nonylphenyl (meth)acrylate.

[0045] Examples of the carboxyl group-containing (meth)acrylate compound as the monofunctional polymerizable component (D) include β-carboxyethyl (meth)acrylate, succinic acid monoacryloyloxyethyl ester, ω-carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hexahydrohydrogen phthalate, and 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate.

[0046] Examples of other (meth)acrylate compounds as the monofunctional polymerizable component (D) include benzyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, acryloylmorpholine, morpholinoethyl (meth)acrylate, trimethylsiloxyethyl (meth)acrylate, diphenyl-2-(meth)acryloyloxyethyl phosphate, 2-(meth)acryloyloxyethyl acid phosphate, kaolin ... Prolactone-modified 2-(meth)acryloyloxyethyl acid phosphate, 2-hydroxy-1-(meth)acryloxy-3-methacryloxypropane, acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, tricyclodecane monomethylol (meth)acrylate, (meth)acrylic acid dimer, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl oxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-ethylhexyl-diglycol (meth)acrylate, aminoethyl (meth)acrylate, ethyl carbitol acrylate, ethyl diglycol acrylate, dimethylaminoethyl acrylate benzyl chloride quaternary salt, tribromophenyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, cresol (meth)acrylate, trimethylolpropane Examples of the acrylate include formal (meth)acrylate, neopentyl glycol (meth)acrylic acid benzoate, 1-(meth)acryloylpiperidin-2-one, 2-(meth)acrylic acid-1,4-dioxaspiro[4,5]decy-2-ylmethyl, N-(meth)acryloyloxyethylhexahydrophthalimide, γ-butyrolactone (meth)acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, imide acrylate, vinyl (meth)acrylate, and maleimide.

[0047] Examples of the styrene-based compound as the monofunctional polymerizable component (D) include styrene, vinyltoluene, p-hydroxystyrene, p-chlorostyrene, p-bromostyrene, p-methylstyrene, p-methoxystyrene, p-t-butoxystyrene, p-t-butoxycarbonylstyrene, p-t-butoxycarbonyloxystyrene, 2,4-diphenyl-4-methyl-1-pentene, and divinylbenzene.

[0048] Examples of the arylate compound as the monofunctional polymerizable component (D) include allyl glycidyl ether, diallyl phthalate, triallyl trimellitate, and isocyanuric acid triallylate.

[0049] Furthermore, the monofunctional polymerizable component (D) may be vinyl acetate, vinyl monochloroacetate, vinyl benzoate, vinyl pivalate, vinyl butyrate, vinyl laurate, divinyl adipate, vinyl crotonate, vinyl 2-ethylhexanoate, three-membered ring compounds (e.g., vinylcyclopropanes, 1-phenyl-2-vinylcyclopropanes, 2-phenyl-3-vinyloxiranes, 2,3-divinyloxiranes, etc.), cyclic ketene acetals (e.g., 2-methylene-1,3-dioxepane, 2-methylene-4-phenyl-1,3-dioxepane, 4,7-dimethyl-2-methylene-1,3-dioxepane, 5,6-benzo-2-methylene-1,3-dioxepane, etc.), or the like.

[0050] It may be preferable that at least a portion of the monofunctional polymerizable component (D) is a monofunctional (meth)acrylate monomer, the polymer of which has a glass transition temperature of 10° C. or lower. More specifically, in the ink composition, the proportion of the total amount of monofunctional (meth)acrylate monomers, the polymer of which has a glass transition temperature of 10° C. or lower, relative to the total amount of polymerizable components is preferably 30% by mass or higher, more preferably 35% by mass or higher, and even more preferably 40% by mass or higher.

[0051] When the ink composition contains a monofunctional (meth)acrylate monomer having a polymer glass transition temperature of 10° C. or less at a certain level or higher, the flexibility and stretchability of the cured coating film can be improved.

[0052] The polymerizable component (A) and the monofunctional polymerizable component (B) may also be monofunctional (meth)acrylate monomers whose polymers have a glass transition temperature of 10° C. or lower; however, the monofunctional polymerizable component (B) often has a polymer whose glass transition temperature exceeds 10° C. Therefore, the total amount of monofunctional (meth)acrylate monomers whose polymers have a glass transition temperature of 10° C. or lower may be the total amount of the polymerizable component (A) and the monofunctional polymerizable component (D) whose polymers have a glass transition temperature of 10° C. or lower.

[0053] [1-5. Photopolymerization initiator] The ink composition of the present invention may contain a photopolymerization initiator. In particular, when the ink composition is to be cured by irradiation with ultraviolet light, it is preferable that the ink composition contains a photopolymerization initiator. On the other hand, when the ink composition is to be cured by irradiation with an electron beam, it usually does not contain a photopolymerization initiator.

[0054] The photopolymerization initiator generates active species such as radicals upon irradiation with active energy rays, thereby initiating photopolymerization of the active energy ray-curable composition. Examples of the photopolymerization initiator include acylphosphine oxide compounds, triazine compounds, aromatic ketone compounds, aromatic onium salt compounds, organic peroxides, thioxanthone compounds, thiophenyl compounds, anthracene compounds, hexaarylbisimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, halogenated hydrocarbon compounds and alkylamine compounds, iodonium salt compounds, and sulfonium salt compounds.

[0055] Preferred examples of the photopolymerization initiator include acylphosphine oxide compounds; diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide are preferred, with phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide being more preferred. The inclusion of an acylphosphine oxide compound as a photopolymerization initiator further enhances the curability of the ink composition of the present invention. The content of the photopolymerization initiator in the ink composition varies depending on the type of photopolymerization initiator, but is typically in the range of 3 to 10% by mass.

[0056] [1-6. Sensitizer and Polymerization Inhibitor] The ink composition of the present invention may contain a sensitizer. The sensitizer can improve the curing properties of the ink composition. Examples of sensitizers include anthracene-based sensitizers such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene; and thioxanthone-based sensitizers such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. The sensitizer is preferably a thioxanthone-based sensitizer. The content of the sensitizer in the ink composition is, for example, about 0.1 to 3.0% by mass.

[0057] The ink composition of the present invention may also contain a polymerization inhibitor. The polymerization inhibitor can suppress unintended polymerization reactions (such as polymerization reactions that occur in the absence of active energy ray irradiation). Examples of polymerization inhibitors include hydroquinone, dibutylhydroxytoluene, hydroquinone monomethyl ether, and phenothiazine. The content of the polymerization inhibitor in the ink composition is, for example, about 0.1 to 3.0% by mass.

[0058] [1-7. Colorant and Pigment Dispersant] The ink composition of the present invention may contain a colorant. The colorant may be a pigment or a dye, but is preferably a pigment. The pigment is a component added to the ink composition to impart coloring power, hiding power, etc., and examples thereof include colored pigments, white pigments, metal powders, etc., and examples thereof include, without particular limitation, the following organic and / or inorganic pigments.

[0059] Examples of pigments include dye lake pigments, azo-based, benzimidazolone-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigo-based, thioindigo-based, perylene-based, perinone-based, diketopyrrolopyrrole-based, isoindolinone-based, nitro-based, nitroso-based, flavanthrone-based, quinophthalone-based, pyranthrone-based, and indanthrone-based organic pigments, and various inorganic pigments.

[0060] Examples of preferred pigments include yellow pigments such as disazo yellow (Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 1), Hansa Yellow, Pigment Yellow 150, and Pigment Yellow 155; magenta pigments such as Brilliant Carmine 6B, Lake Red C, Watching Red, Quinacridone, Pigment Red 122, and Pigment Red 254; cyan pigments such as phthalocyanine blue, phthalocyanine green, alkali blue, and Pigment Blue 15:4; colored pigments (including achromatic colored pigments such as white and black) such as titanium oxide (Pigment White 6, etc.), red iron oxide, antimony red, cadmium yellow, cobalt blue, Prussian blue, ultramarine blue, iron black, chromium oxide green, carbon black (Pigment Black 7, etc.), and graphite; and metal powders such as aluminum paste and bronze powder.

[0061] The content of the pigment in the ink composition varies depending on the type of pigment and the desired degree of coloring, and is not particularly limited, but can be, for example, about 1.0 to 10.0% by mass of the entire ink composition.

[0062] When the ink composition of the present invention contains a pigment, it may further contain a pigment dispersant for dispersing the pigment. The pigment dispersant is preferably a polymeric pigment dispersant, and is also preferably a pigment dispersant containing a basic group. Examples of pigment dispersants containing a basic group include polymeric pigment dispersants such as basic group-containing polyester pigment dispersants, basic group-containing acrylic pigment dispersants, basic group-containing urethane pigment dispersants, and basic group-containing carbodiimide pigment dispersants, as well as anionic surfactants.

[0063] The polymeric pigment dispersant is not particularly limited, but may be a linear polymer having a pigment-affinity moiety consisting of a basic group at least at one or both ends of the main chain due to a block or graft structure. The polymeric pigment dispersant may contain 2 to 3,000 basic groups per molecule and may have a number average molecular weight of 1,000 to 1,000,000.

[0064] The content of the pigment dispersant in the ink composition is preferably 1.0 to 200.0 parts by mass when the total amount of the pigment is taken as 100 parts by mass.

[0065] [1-8. Surfactants and Other Additives] The ink composition of the present invention may contain a surfactant. The surfactant reduces the surface tension of the ink composition, thereby increasing the wetting ability of the ink composition to the substrate to be printed, and also increasing the quick-drying ability of the ink composition. Examples of surfactants include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants, and silicone-based surfactants.

[0066] Preferred examples of surfactants include silicone surfactants, fluorine surfactants, and acetylene surfactants, with silicone surfactants being more preferred. Examples of silicone surfactants include polyether-modified silicone oils such as hydroxyl group-containing polyether-modified polydimethylsiloxanes and polyether-modified polydimethylsiloxanes, polyester-modified polydimethylsiloxanes, and polyester-modified methylalkylpolysiloxanes such as polyester-modified polymethylalkylsiloxanes. Silicone surfactants are also commercially available, and are available as BYK-307, BYK-315, BYK-331, BYK-333, BYK-347, BYK-348, BYK-349, BYK-345, BYK-377, BYK-378, BYK-3455 (BYK Corporation), and the like.

[0067] The content of the surfactant in the ink composition is preferably set so that the surface tension of the ink composition is 20.0 to 36.0 mN / m, and can be, for example, in the range of 0.10 to 1.50 mass% with respect to the actinic energy ray-curable inkjet ink composition.

[0068] The ink composition of the present invention may contain other additives, and examples of such other additives include solvents, ultraviolet absorbers, antioxidants, antifoaming agents, storage stability improvers, antifungal agents, antirust agents, thickeners, moisturizing agents, pH adjusters, etc. The content of the solvent in the ink composition is preferably 5.0% by mass or less, more preferably 2.0% by mass or less, and the ink composition may not contain any solvent.

[0069] 2. Physical Properties of Ink Composition for Ink Jet Printing The photocurable ink composition for ink jet printing of the present invention may be printed using an ink jet device and may have physical properties that do not impair curability by actinic energy rays.

[0070] [2-1. Viscosity] The viscosity of the photocurable ink composition for inkjet printing at 25°C is preferably 5.0 mPa·s or more, more preferably 10.0 mPa·s or more, and even more preferably 15.0 mPa·s or more; and preferably 100.0 mPa·s or less, 60.0 mPa·s or less, more preferably 46.0 mPa·s or less, and even more preferably 25.0 mPa·s or less. The viscosity of the ink composition can be adjusted mainly by the composition of the photopolymerizable component, and may also be adjusted by adding a viscosity modifier or the like, as necessary. The viscosity described in this specification is a viscosity measured using an E-type viscometer (RE100L type viscometer, manufactured by Toki Sangyo Co., Ltd.) at 25°C and 10 rpm. If the viscosity is less than 5.0 mPa·s or more than 100.0 mPa·s, the ejection stability during inkjet printing may be reduced.

[0071] [2-2. Surface tension] The surface tension of the photocurable inkjet printing ink composition at 25°C is preferably 20.0 to 36.0 mN / m. The surface tension of the ink composition can be adjusted by blending a surfactant (leveling agent) as needed. The surface tension can be measured at a temperature of 25°C using a dynamic wettability tester (for example, trade name: WET-6000, manufactured by Rhesca Co., Ltd.).

[0072] [3. Preparation of Ink Composition for Ink Jet Printing] The ink composition of the present invention can be prepared according to a conventionally known method. For example, the ink composition can be obtained by dispersing and mixing the components using a dispersing machine such as a wet circulation mill, a bead mill, a ball mill, a sand mill, an attritor, a roll mill, a DCP mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a high-pressure homogenizer (e.g., Microfluidizer, Nanomizer, Ultimizer, Genus PY, DeBEE2000), or a pearl mill, and adjusting the viscosity as necessary.

[0073] In addition, when the ink composition contains a pigment, the ink composition can also be prepared by first obtaining a base ink composition (also called a pigment dispersion) by mixing the pigment, the pigment dispersant, and the polymerizable component, and then adding the remaining components to the base ink composition so as to obtain a desired composition.

[0074] [4. Inkjet Printing] The ink composition of the present invention can be used for printing using an inkjet printing device. The type of inkjet printing device that can be used is not particularly limited, and may be a line head type (single pass type) or a serial head type (multi-pass type). A continuous type inkjet printing device may also be used, in which case the conductivity of the ink composition can be adjusted by further adding a conductivity imparting agent.

[0075] The ink composition is supplied to a printer head of an inkjet printing device, and ejected from the printer head onto a substrate to be printed. The ink composition is ejected from the printer head onto the substrate (printing of an image) so that the thickness of the coating film on the substrate is, for example, 1 to 60 μm.

[0076] The ink composition that has landed on the printing substrate is exposed to actinic energy rays and cured. Examples of actinic energy rays include ultraviolet rays emitted from light-emitting diodes (LEDs), various lamps, and electrodes, electron beams, and visible light. From an environmental perspective, it is preferable to use a light-emitting diode (LED) that emits ultraviolet light with an emission peak wavelength in the range of 350 to 420 nm as the light source.

[0077] The substrate to be printed on is not particularly limited, as long as it is a substrate to which a conventionally known photocurable inkjet printing ink composition can be applied. Examples of substrates include plastic, paper, capsules, gel, metal foil, glass, wood, and cloth. A cured coating film of the ink composition of the present invention has excellent flexibility and stretchability. Therefore, it may be preferable to print the ink composition of the present invention on a flexible substrate, such as a plastic film.

[0078] Examples of plastics that may be used to form the printing substrate include polyester polymers (e.g., polyethylene terephthalate (PET), polyethylene naphthalate, etc.), cellulose polymers (e.g., diacetyl cellulose, triacetyl cellulose (TAC), etc.), polycarbonate polymers, polyacrylic polymers (e.g., polymethyl methacrylate, etc.), vinyl chloride polymers, polyolefin polymers (e.g., polyethylene, polypropylene, polyolefin polymers having a cyclic or norbornene structure, ethylene-propylene copolymer polymers, etc.), polyamide polymers (e.g., nylon, aromatic polyamide polymers, etc.), polystyrene polymers (e.g., polystyrene, acrylonitrile-styrene copolymer polymers, etc.), polyimide polymers, polysulfone polymers, polyethersulfone polymers, polyetherketone polymers, polyphenylsulfide polymers, polyvinyl alcohol polymers, polyvinylidene chloride polymers, polyvinyl butyral polymers, polyarylate polymers, polyoxymethylene polymers, polyepoxy polymers, and blends of these polymers.

[0079] A. Preparation of Ink Compositions for Ink Jet Printing Ink compositions for each of the Examples and Comparative Examples were prepared using the following components. That is, each ink composition for ink jet printing was prepared by blending the components according to the formulation shown in Tables 1 to 3, and stirring and mixing them.

[0080] A-1. Polymerizable component (A) - (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate (MEDOL-10, glass transition temperature: -7°C) A-2. Monofunctional polymerizable component (B) - Acryloylmorpholine (glass transition temperature: 145°C) - N-vinyl-5-methyl-2-oxazolidinone A-3. Multifunctional polymerizable component (C) Amine-modified oligomer (CN371, bifunctional) 1,6-hexanediol diacrylate (1,6-HDDA, MW=226) 3-methyl-1,5-pentanediol diacrylate (MW=226) Dipropylene glycol diacrylate (DPGDA, MW=242) Trimethylolpropane (EO)3 triacrylate (trimethylolpropane (EO)3 TA, MW=428) PEG400 diacrylate (MW=508) Bisphenol A (EO)4 diacrylate (bisphenol A (EO)4DA, MW=512) A-4. Other monofunctional polymerizable components (D): t-butylcyclohexyl acrylate (TBCHA, glass transition temperature: 65°C), benzyl acrylate (glass transition temperature: 6°C), ethyl carbitol acrylate (EEEA, glass transition temperature: -67°C).

[0081] A-5. Photopolymerization initiator: Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) A-6. Sensitizer: 2,4-diethylthioxanthone (DETX) A-7. Polymerization inhibitor: 4-methoxyphenol (MEHQ) A-8. Surfactant: Polyester-modified polymethylalkylsiloxane (BYK-315N)

[0082] A-9. Coloring pigments: Phthalocyanine blue pigment (PB15:4) Quinacridone magenta pigment (PR122) Nickel azo yellow pigment (PY150) Carbon black (PBk7) A-10. Pigment dispersants: Solsperse SS32000 (Lubrizol Corporation) Ajisper PB821 (Ajinomoto Fine-Techno Co., Ltd.)

[0083] B. Evaluation of Ink Compositions and Cured Coating Films (Printed Matter) The ink compositions prepared in each of the Examples and Comparative Examples, and the cured coating films of the printed matter thereof, were evaluated for the following points, and the evaluation results are shown in Tables 1 to 3.

[0084] B-1. Viscosity of Ink Composition Using an E-type viscometer (product name: RE100L type viscometer, manufactured by Toki Sangyo Co., Ltd.), the viscosity of the ink composition of Example 1 was measured (10.0 cps) at a temperature of 25°C and a rotor rotation speed of 20 rpm. Furthermore, the viscosity of the ink compositions of each of the Examples and Comparative Examples other than Example 1 was measured, and the viscosity increase compared to Example 1 was used to evaluate the viscosity according to the following criteria: 5: Viscosity increase of less than +1 cps based on Example 1 4: Viscosity increase of +1 to less than +2 cps based on Example 1 3: Viscosity increase of +2 to less than +3 cps based on Example 1 2: Viscosity increase of +3 to less than +4 cps based on Example 1 1: Viscosity increase of +4 cps or more based on Example 1

[0085] B-2. Curability of Ink Compositions The photocurable inkjet printing ink compositions obtained in the Examples and Comparative Examples were applied to a polyvinyl chloride film PVC80 (manufactured by Lintec Corporation) using a No. 8 bar coater. The coating was then cured by irradiating it with light using a conveyor-type light irradiation device (Heraeus STM-250E-16, lamp: Z-8 lamp (metal halide type)) at 120W x 50m / min with a UV cumulative light dose of 150mJ / cm2 (the UV cumulative light dose was determined by measuring the dose at the following wavelengths using an EIT UVIMAP (UM365H-S) measuring device). After each pass, the coating was rubbed with a cotton swab, and the curability was evaluated according to the following criteria. 5: After one pass, the coating film shows no uncured ink on the cotton swab. 4: After two passes, the coating film shows no uncured ink on the cotton swab. 3: After three passes, the coating film shows no uncured ink on the cotton swab. 2: After four passes, the coating film shows no uncured ink on the cotton swab. 1: After four passes, the coating film shows uncured ink on the cotton swab.

[0086] B-3. ​​Adhesion of Cured Coating Film to Substrate The photocurable inkjet printing ink compositions obtained in the Examples and Comparative Examples were applied to a substrate using a No. 8 bar coater. They were then cured using a conveyor-type light irradiation device (Heraeus STM-250E-16, lamp: Z-8 lamp (metal halide type)) at 120W x 50m / min with a UV cumulative light dose of 500mJ / cm2 (the UV cumulative light dose was determined using an EIT UVIMAP (UM365H-S) measuring device over the following measurement ranges: 250-260nm, 280-320nm, 320-390nm, and 395-445nm). The coating was then rubbed with a cotton swab and allowed to cure until no uncured ink remained on the cotton swab.

[0087] A cured coating film of each ink composition prepared on an acrylic plate (Acrylite L / S manufactured by Mitsubishi Chemical Corporation) was cross-cut with a cutter knife, and cellophane tape (product name: Cellotape (registered trademark), manufactured by Nichiban Co., Ltd.) was applied to the cut area and then peeled off to evaluate the degree of peeling of the cured coating film according to the following criteria: 5: Peeling of the coating film is less than 5% by area 4: Peeling of the coating film is 5 to less than 15% by area 3: Peeling of the coating film is 15 to less than 35% by area 2: Peeling of the coating film is 35 to less than 65% by area 1: Peeling of the coating film is 65% or more by area

[0088] B-4. Alcohol resistance of cured coating film Using the same method as in B-3 above, a cured coating film of each ink composition was prepared on a polyvinyl chloride film PVC80 (manufactured by Lintec Corporation). The cured coating film was rubbed with a cotton swab dipped in a 50% aqueous ethanol solution, and alcohol resistance was evaluated based on the number of times the cotton swab was rubbed back and forth, using the following criteria: 5: The base of the cured coating film is not exposed after 50 strokes; 4: The base of the cured coating film is exposed after 40 to 50 strokes; 3: The base of the cured coating film is exposed after 30 to 39 strokes; 2: The base of the cured coating film is exposed after 20 to 29 strokes; 1: The base of the cured coating film is exposed after 19 strokes or less.

[0089] B-5. Flexibility of cured coating film Using the same method as in B-3 above, a cured coating film of each ink composition was prepared on a polyvinyl chloride sheet PVC plate (T938 manufactured by Takiron C.I. Co., Ltd.). The resulting print was bent 180°, and the cured coating film was visually inspected for cracks, and rated according to the following criteria: 5: No cracks in the coating film 4: Cracks in the coating film occurred in less than 10% of the entire bent area 3: Cracks in the coating film occurred in 10 to less than 30% of the entire bent area 2: Cracks in the coating film occurred in 30 to less than 50% of the entire bent area 1: Cracks in the coating film occurred in 50% or more of the entire bent area

[0090] B-6. Stretchability of cured coating film Using the same method as in B-3 above, a cured coating film of each ink composition was prepared on a polyvinyl chloride seeded PVC plate (T938 manufactured by Takiron C.I.). The resulting print was cut into a 2 cm x 5 cm piece, and the coating film was visually inspected for cracks when stretched 100% (uniaxial stretching). The evaluation was based on the following criteria: 5: No cracks in the coating film occurred even when stretched 100% 4: Cracking occurred in the coating film when stretched from 75% to 100% 3: Cracking occurred in the coating film when stretched from 50% to less than 75% 2: Cracking occurred in the coating film when stretched from 25% to less than 50% 1: Cracking occurred in the coating film when stretched less than 25%

[0091] B-7. Odor of cured coating film Using the same method as in B-3 above, a cured coating film of each ink composition was prepared on a polyvinyl chloride film PVC80 (manufactured by Lintec Corporation). The resulting print was cut to 8 cm x 12 cm, placed in a 24 cm x 34 cm zipper bag, and sealed. After one hour, the odor inside the bag was checked by 10 subjects at room temperature of 20°C and evaluated according to the following criteria, and the average of the 10 evaluation values ​​(rounded to the nearest whole number) was obtained. 5: Almost no odor 4: Slight odor 3: Moderate odor 2: Strong odor 1: Very strong odor

[0092] B-8. Tackiness of cured coating film Using the same method as in B-3 above, a cured coating film of each ink composition was prepared on a polyvinyl chloride film PVC80 (manufactured by Lintec Corporation). The prepared cured coating film was touched with a finger, and the condition of the coating film surface was visually confirmed, and tackiness was evaluated according to the following criteria: ◯: No fingerprints adhere to the coating film Δ: Slight fingerprints adhere to the coating film ×: Fingerprints adhere to the coating film

[0093]

[0094]

[0095]

[0096] As shown in Comparative Example 1 (Table 2), the ink composition not containing MEDOL-10 as the polymerizable component (A) exhibited an odor and tackiness in the cured coating film, resulting in a deterioration in the quality of the ink print. As shown in Comparative Example 2 (Table 2), the ink composition not containing the monofunctional polymerizable component (B) exhibited reduced curability and also exhibited an odor and tackiness in the cured coating film. As shown in Comparative Example 3 (Table 2), when the weight ratio (A / B) of the polymerizable component (A) to the monofunctional polymerizable component (B) was high (3.0), a similar tendency to Comparative Example 1 (Table 2) was observed, resulting in an odor and tackiness in the cured coating film. Furthermore, as shown in Comparative Example 4 (Table 3), when the weight ratio (A / B) of the polymerizable component (A) to the monofunctional polymerizable component (B) was low (0.17) and the proportion of monofunctional monomers with glass transition temperatures of 10°C or less was low (approximately 25% by mass), a tendency toward decreased flexibility and stretchability was observed. In contrast, the ink compositions of the examples containing the polymerizable component (A) and the monofunctional polymerizable component (B) in an appropriate ratio suppressed the occurrence of odor and tackiness in the cured coating film, and other coating film properties were also satisfactory.

[0097] As shown in Comparative Example 5 (Table 3), an ink composition containing 1,6-hexanediol diacrylate, a polyfunctional (meth)acrylate monomer with a molecular weight of 500 or less, as the polyfunctional polymerizable component (C), but not containing an amine-modified oligomer, exhibited poor curability, reduced alcohol resistance of the cured coating film, and tackiness. Also, as shown in Comparative Example 6 (Table 3), an ink composition containing an amine-modified oligomer as the polyfunctional polymerizable component (C) but not containing a polyfunctional (meth)acrylate monomer exhibited poor alcohol resistance of the cured coating film and tackiness. Furthermore, as shown in Comparative Example 7 (Table 3), an ink composition not containing a polyfunctional polymerizable component (C) exhibited poor alcohol resistance of the cured coating film, resulting in tackiness and odor. On the other hand, as shown in Comparative Example 8 (Table 3), an ink composition containing a high content of polyfunctional polymerizable component (C) relative to the total content of the polymerizable components also exhibited poor flexibility and stretchability of the cured coating film. In contrast, the ink compositions of the examples, which contained a predetermined amount of an amine-modified oligomer and a polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less as the polyfunctional polymerizable component (C), suppressed the occurrence of odor and tackiness in the cured coating film, and other coating film properties were also satisfactory.

[0098] As shown in Comparative Example 9 (Table 3), an ink composition containing an amine-modified oligomer and PEG400 diacrylate with a molecular weight exceeding 500 (molecular weight 508) as the multifunctional polymerizable component (C) increased the viscosity of the ink composition, reduced the alcohol resistance of the cured coating film, and caused tackiness. Furthermore, as shown in Comparative Examples 10 and 11 (Table 3), an ink composition containing an amine-modified oligomer and bisphenol A (EO)4 diacrylate with a molecular weight exceeding 500 (molecular weight 512) as the multifunctional polymerizable component (C) tended to increase the viscosity. Decreasing the content of bisphenol A (EO)4 diacrylate tended to improve the viscosity increase, but reduced the alcohol resistance and caused tackiness. In contrast, the ink compositions of each Example, which contained a predetermined amount of an amine-modified oligomer and a multifunctional (meth)acrylate monomer with a molecular weight of 500 or less as the multifunctional polymerizable component (C), suppressed odor and tackiness in the cured coating film, and other coating film properties were also satisfactory.

[0099] As shown in Examples 1 to 3 (Table 1), all of the ink compositions containing component (A) MEDOL-10 and component (B) acryloylmorpholine and / or N-vinyl-5-methyl-2-oxazolidinone in a 1:1 ratio suppressed the odor and tackiness of the cured coating film, and other coating film properties were also satisfactory.

[0100] As shown in Example 1 and Examples 4 and 5 (Table 1), all of the ink compositions in which the content of component (A) MEDOL-10 was adjusted to be in the range of 5.0 to 30.0 mass% relative to the ink composition suppressed the occurrence of odor and tackiness in the cured coating film, and other coating film physical properties were also satisfactory. Furthermore, as shown in Example 1 and Examples 5 and 6 (Table 1), all of the ink compositions in which the content ratio (A / B) of component (A) MEDOL-10 to component (B) acryloylmorpholine was adjusted to be in the range of 0.2 to 2.0 suppressed the occurrence of odor and tackiness in the cured coating film, and other coating film physical properties were also satisfactory.

[0101] As shown in Example 7 (Table 1), the ink composition containing 0.5 mass % of the amine-modified oligomer significantly suppressed the odor and tackiness of the cured coating film, and other coating film physical properties were also satisfactory, compared to the ink composition of Comparative Example 5 (Table 3), which did not contain the amine-modified oligomer. As shown in Examples 8 and 9 (Table 1), the ink compositions in which the content of 1,6-hexanediol diacrylate, component (C), was set slightly higher relative to the total amount of the polymerizable components also suppressed the odor and tackiness of the cured coating film, and other coating film physical properties were also satisfactory.

[0102] As shown in Example 1 (Table 1) and Examples 10 to 12 (Table 2), ink compositions containing an amine-modified oligomer and a polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less, such as 1,6-hexanediol diacrylate (molecular weight 226), 3-methyl-1,5-pentanediol (molecular weight 226), dipropylene glycol diacrylate (molecular weight 242), or trimethylolpropane (EO) triacrylate (molecular weight 428), as the polyfunctional polymerizable component (C) exhibited reduced odor and tackiness in the cured coating film and also exhibited satisfactory other coating film physical properties, compared to Comparative Examples 9 to 11 (Table 3) (ink compositions containing a polyfunctional (meth)acrylate monomer having a molecular weight of more than 500). Thus, by combining an amine-modified oligomer with a polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less as the polyfunctional polymerizable component (C), it is possible to suppress the odor and tackiness in the cured coating film and to sufficiently improve other coating film physical properties.

[0103] Furthermore, as shown in Example 1 (Table 1) and Examples 13 to 15 (Table 2), even when the type of color pigment contained in the ink composition of the present invention is changed, it is possible to suppress the occurrence of odor and tackiness in the cured coating film and to sufficiently improve other physical properties of the coating film.

[0104] The ink composition for inkjet printing of the present invention can be applied to various print media by inkjet coating and curing to obtain printed matter. The resulting cured coating film has excellent physical properties, such as no odor or tackiness, and good stretchability and flexibility. Therefore, the printed matter can be used in a variety of applications, such as signage (billboards, posters, etc.), labels, printing on metal substrates, and food packaging films.

Claims

1. An ink composition for inkjet printing, comprising a polymerizable component (A) represented by the following structural formula (X), a monofunctional polymerizable component (B) consisting of a (meth)acrylamide compound and / or an N-vinyl compound, and a polyfunctional polymerizable component (C) containing an amine-modified oligomer and a polyfunctional (meth)acrylate monomer having a molecular weight of 500 or less, wherein the weight ratio ((A) / (B)) of the polymerizable component (A) to the monofunctional polymerizable component (B) is in the range of 0.2 to 2.0, and the content of the polyfunctional polymerizable component (C) relative to the total amount of all polymerizable components is less than 18% by mass. [R in structural formula (X)] １ and R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or a phenyl group, or R １ and R ２ may be bonded to each other to form a cycloalkyl having 3 to 9 carbon atoms; R ３ , R ４ and R ５ each independently represents a hydrogen atom or an alkyl group, R ６ represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 5.

2. The ink composition for ink-jet printing according to claim 1, wherein the content of the polymerizable component (A) in the ink composition for ink-jet printing is 5 to 30% by mass.

3. The ink composition for ink-jet printing according to claim 1 or 2, wherein the content of the amine-modified oligomer in the ink composition for ink-jet printing is 0.5 to 10% by mass.

4. The ink composition for inkjet printing according to claim 1 or 2, wherein the content of the monofunctional (meth)acrylate monomer having a glass transition temperature of 10°C or less is 30% by mass or more relative to the total amount of all polymerizable components.

5. The ink composition for inkjet printing according to claim 1 or 2, wherein the ink composition for inkjet printing contains a photopolymerization initiator containing phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide in an amount of 3 to 10% by mass based on the ink composition for inkjet printing.

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