Active energy ray-curable ink composition for inkjet

Abstract

[Problem] To provide an active energy ray-curable ink composition for inkjet, which has excellent inkjet head discharge ability, forms a printed layer having excellent adhesion to various substrates, has excellent curability, does not tack on the surface after curing, has excellent flexibility when bent together with a substrate, has excellent image quality after curing, and can be used in the field of inkjet printing. The smell is very small after curing. [Solution] An active energy ray-curable inkjet ink composition satisfying the following conditions (A) to (D): (A) the content of an amine-modified oligomer accounting for 1.0% to 20.0% by mass of the total solid content, (B) the content of an alicyclic skeleton-containing monofunctional monomer forming a polymer having a Tg of 10 DEG C to 60 DEG C during polymerization accounting for 16.0% or more by mass of the total solid content, (C) 3-methyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3, 5-trimethyl-1, 3-trimethyl-1 the content of 1, 5-pentanediol diacrylate accounts for 8.0% to 25.0% by mass of the total solid content, and the content of acryloylmorpholine accounts for 3.0% to 15.0% by mass of the total solid content.

Description

Technical Field

[0001] This invention relates to an ink composition for inkjet printing that is cured by active energy rays. Background Technology

[0002] Active energy ray curable inkjet ink compositions are used for printing on a variety of substrates. Inkjet printing is advantageous for small-batch production because it eliminates the need for printing plates. Furthermore, in UV-curable ink compositions, the organic solvent content can be reduced; this is also advantageous in terms of environmental friendliness, as it reduces VOC emissions.

[0003] In printing active energy ray-curable inkjet ink compositions, ink droplets fall onto a target printing substrate and are cured by light irradiation, thereby forming a printed layer consisting of a cured coating on the target printing substrate. However, depending on the material of the target printing substrate and the composition of the ink composition, in some cases, the adhesion between the printed layer formed by the cured coating and the surface of the target printing substrate is insufficient.

[0004] In contrast, it is well known that in active energy ray curable inkjet ink compositions containing compounds with a cyclic structure and a glass transition temperature (Tg) of 90°C or higher and compounds containing a homopolymer with a glass transition temperature (Tg) of -30°C or lower, by incorporating amine-modified acrylate oligomers, printing can be performed at transport speeds of 1.8 m / s or higher during the printing process, and anti-blocking properties can be improved (Patent Document 1).

[0005] Citation List Patent documents Patent Document 1: Japanese patent application pending examination, publication number 2023-059023 Summary of the Invention Technical issues The purpose of this invention is to provide an active energy ray curable ink composition for inkjet printing, which has excellent inkjet head discharge capability, forms a printing layer with excellent adhesion to various substrates, has excellent curability, has no tackiness on the surface after curing, has excellent flexibility when bent together with the substrate, has excellent image quality after curing, and has very little odor after curing.

[0006] Technical solutions to the problem This invention relates to the following active energy ray curable ink composition for inkjet printing.

[0007] 1. An ink composition for inkjet printing that is cured by active energy rays, satisfying the following conditions (A) to (D): (A) The content of amine-modified oligomers, by mass, is 1.0% to 20.0% of the total solids. (B) The content of monofunctional monomers containing an alicyclic skeleton that form polymers with a Tg of 10°C to 60°C during polymerization accounts for more than 16.0% of the total solid content by mass. (C) The content of 3-methyl-1,5-pentanediol diacrylate is 8.0% to 25.0% of the total solids by mass, and (D) Acryloylmorpholine content is 3.0% to 15.0% of the total solids by mass.

[0008] 2. The active energy ray curable inkjet ink composition as described in 1, wherein the content of the amine-modified oligomer accounts for 2.0% to 15.0% of the total solids by mass.

[0009] 3. The active energy ray curable inkjet ink composition as described in 1 or 2, wherein the content of the amine-modified oligomer accounts for 4.0% to 13.0% of the total solids by mass.

[0010] 4. The active energy ray curable inkjet ink composition according to any one of 1 to 3, wherein the content of the monofunctional monomer containing an alicyclic skeleton that forms a polymer with a Tg of 10°C to 60°C during polymerization accounts for more than 18.0% by mass of the total solids content.

[0011] 5. The active energy ray curable inkjet ink composition according to any one of 1 to 4, wherein the content of 3-methyl-1,5-pentanediol diacrylate is 10.0% to 20.0% by mass of the total solids content.

[0012] 6. The active energy ray curable ink composition for inkjet printing as described in any one of 1 to 5, wherein the content of acrylomorpholine is 5.0% to 10.0% by mass of the total solids.

[0013] 7. The active energy ray curable ink composition for inkjet printing as described in any one of 1 to 6, wherein the monofunctional monomer containing an alicyclic skeleton that forms a polymer with a Tg of 10°C to 60°C during polymerization is tert-butylcyclohexyl acrylate.

[0014] 8. The active energy ray curable ink composition for inkjet printing as described in any one of 1 to 7, wherein the contents of benzyl acrylate, tetrahydrofurfuryl acrylate and isobornyl acrylate are each less than 5.0% by mass of the total solids content.

[0015] Advantages of the invention The active energy ray curable ink composition of the present invention satisfies conditions (A) to (D), and therefore exhibits excellent performance in terms of LED curability and discharge stability from a head. Furthermore, the printed layer obtained by curing the active energy ray curable ink composition has the following effects: excellent adhesion to the target printing substrate, flexibility of the printed coating, and image quality; non-sticky surface; and minimal odor. Detailed Implementation

[0016] [1. Composition of ink compositions for active energy ray curable inkjet printers] The active energy ray curable ink composition for inkjet printing (hereinafter sometimes simply referred to as "ink composition") of the present invention substantially satisfies the following conditions (A) to (D): (A) The content of amine-modified oligomers ranges from 1.0% to 20.0% by mass. (B) The content of monofunctional monomers containing an alicyclic skeleton that form polymers with a Tg of 10°C to 60°C during polymerization is 16.0% or more by mass. (C) The content of 3-methyl-1,5-pentanediol diacrylate is 8.0% to 25.0% by mass, and (D) The content of acrylamide is 3.0% to 15.0% by mass.

[0017] In this invention, the content of each component is a value when the total solids content in the ink composition is 100% by mass. Total solids content is the sum of components excluding solvents that do not remain in the printed layer. However, reactive solvents that react to form the cured ink composition film are included in the components constituting the total solids content.

[0018] In addition to the components described above, the ink composition may optionally contain 1) a pigment, 2) a pigment dispersant, 3) a photopolymerizable compound, 4) a photopolymerization initiator, and 5) any other component. Known active energy rays (such as ultraviolet light and electron beams) suitable for polymerizing photopolymerizable compounds can be used as active energy rays. When using an electron beam, the ink composition may be free of a photopolymerization initiator.

[0019] [(A) The content of amine-modified oligomers is 1.0% to 20.0% of the total solids by mass.] The ink composition contains amine-modified oligomers, which are photopolymerizable compounds comprising 1.0% to 20.0% of the total solids in the ink composition by mass. The amine-modified oligomer is a component containing amine groups, whose olefinic unsaturated bonds polymerize to increase its molecular weight. As a component with a relatively high molecular weight before polymerization, the amine-modified oligomer can impart appropriate viscosity and elasticity to the ink composition. Furthermore, the relatively high polarity of the amine-modified oligomer can impart good adhesion / tack to non-absorbent media to the cured ink composition. The amine-modified oligomer can improve the photocurability of the ink composition and the quality of the printed image.

[0020] Amine-modified oligomers are oligomers having one or more amino groups and one or more photopolymerizable functional groups in their molecules, preferably oligomers having two or more photopolymerizable functional groups (polyfunctional amine-modified oligomers). The photopolymerizable functional group is preferably a (meth)acryloyl group. Amine-modified oligomers are preferably amine-modified (meth)acrylate oligomers having two or more (meth)acryloyl groups and one or more amino groups in their molecules. In this specification, "(meth)acrylate" means "acrylate and / or methacrylate," and "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid."

[0021] Amine-modified (meth)acrylate oligomers can be synthesized by polymerization of desired monomers, or they can be commercially available products. Examples of commercially available products include GENOMER 5161 and GENOMER 5275 (RAHN); CN371, CN371NS, CN373, CN383, CN384, CN386, CN501, CN503, CN550, and CN551 (Sartomer Inc.); EBECRYL80, EBECRYL 81, EBECRYL 83, EBECRIL 7100, EBECRYL 84, and EBECRYR P115 (Daicel-Allnex Ltd.); LAROMER PO 83F, LAROMER PO 84F, Laromer LR 8946, Laromer LR 8956, Laromer LR 8996, and Laromer LR 8894 (BASF); AgiSyn 001, AgiSyn002, Agisyn 003 and Agisyn 008 (DSM Coating Resins Ltd.); Photomer4771, Photomer 4775, Photomer 4967, Photomer 5006, Photomer 5096, Photomer 5662 and Photomer 5930 (Cognis); and Doublecure EPD, Doublecure OPD, Doublecure 115, Doublecure 225, Doublecure 645, PolyQ 222, PolyQ 226, PolyQ 224 and PolyQ 101 (Double Bond Chemical Ind. Co., Ltd.)

[0022] There is no limitation on the viscosity of the amine-modified oligomer, but the viscosity at 25°C is preferably below 2000 mPa•s, so as to set the viscosity of the entire active energy ray curable inkjet ink composition within an appropriate range.

[0023] The content of amine-modified oligomers in the ink composition is from 1.0% to 20.0% of the total solids in the ink composition by mass. Preferably, the content is 2.0% or more of the total solids by mass, more preferably 4.0% or more of the total solids by mass, and even more preferably 6.0% or more of the total solids by mass. Preferably, the content is 17.0% or less by mass, more preferably 15.0% or less by mass, and even more preferably 13.0% or less by mass. A content of less than 1.0% of amine-modified oligomers by mass may lead to deterioration in image quality and LED curability. A content of more than 20.0% of amine-modified oligomers by mass may lead to deterioration in head ejection capability (ejection stability).

[0024] [(B) The content of monofunctional monomers containing an alicyclic backbone that form polymers with a Tg of 10°C to 60°C during polymerization accounts for more than 16.0% by mass of the total solids content.] B) Examples of monofunctional monomers containing an alicyclic skeleton that form polymers with a Tg of 10°C to 60°C during polymerization include trimethylcyclohexyl acrylate (TMCHA) (Tg: 52°C), cyclohexyl acrylate (CHA) (Tg: 15°C), cyclohexanediol monoacrylate (Tg: 18°C), and 4-tert-butylcyclohexyl acrylate (Tg: 34°C) (referred to as TBCH or TBCHA).

[0025] The content of monofunctional monomers containing alicyclic skeletons that form polymers with a Tg of 10°C to 60°C during polymerization in the ink composition is 16.0% or more by mass of the total solids content in the ink composition. Preferably, the content is 20.0% or more by mass, more preferably 25.0% or more by mass. Preferably, the content is 45.0% or less by mass, more preferably 40.0% or less by mass. In particular, when the content is less than 16.0% by mass of the total solids content, the adhesion of the polyethylene terephthalate resin decreases, and the flexibility and image quality deteriorate.

[0026] Monofunctional monomers containing an alicyclic skeleton that form polymers with a Tg of 10°C to 60°C during polymerization are alicyclic compounds whose molecules contain carbon atoms.

[0027] [The content of (C) 3-methyl-1,5-pentanediol diacrylate is 8.0% to 25.0% of the total solids by mass.] The ink composition contains 8.0% to 25.0% (by weight) of 3-methyl-1,5-pentanediol diacrylate (MPDA) of the total solids content. Therefore, the ink composition exhibits excellent head ejection stability. Furthermore, the printed layer obtained by curing the ink composition demonstrates excellent adhesion to the target printing substrate, flexibility of the printed coating, and image quality, and has a non-sticky surface. The content is preferably 9.0% or more (by weight), more preferably 10.0% or more (by weight), and even more preferably 11.0% or more (by weight). The content is preferably 23.0% or less (by weight), more preferably 20.0% or less (by weight), and even more preferably 19.0% or less (by weight). When the content is less than 8.0% (by weight), the printed and cured coating is sticky, and the printed image quality deteriorates. When the content exceeds 25.0% (by weight), the adhesion of polyethylene terephthalate decreases, and the flexibility and image quality deteriorate.

[0028] Furthermore, if the content of 3-methyl-1,5-pentanediol diacrylate does not account for 8.0% to 25.0% of the total solids by mass and another multifunctional polymeric compound is contained, the effect provided when the content of 3-methyl-1,5-pentanediol diacrylate is the predetermined content as described above will not be provided.

[0029] [(D) Acryloylmorpholine content, by mass, is 3.0% to 15.0% of the total solids.] The ink composition contains 3.0% to 15.0% acrylamide morpholine by weight of the total solids content. The content is preferably 4.0% or more by weight, more preferably 5.0% or more by weight. The content is preferably 13.0% or less by weight, more preferably 10.0% or less by weight. When the content is less than 3.0% by weight, the tackiness and curability of the coating surface may deteriorate. When the content exceeds 15.0% by weight, the flexibility and adhesion may deteriorate.

[0030] <Other photopolymerizable compounds> [Other monofunctional monomers (excluding monofunctional monomers containing alicyclic skeletons that form polymers with a Tg of 10°C to 60°C during polymerization and acrylamide morpholine)] Other monofunctional monomers that may be contained in the ink composition may be used alone or in combination of two or more. Monomers may be unsaturated carboxylic acid compounds, alkyl (meth)acrylate compounds, hydroxyl-containing (meth)acrylate compounds, halogen-containing (meth)acrylate compounds, ether-containing (meth)acrylate compounds, carboxyl-containing (meth)acrylate compounds, amide-containing monofunctional monomers, other (meth)acrylate compounds, styrene compounds, N-vinyl compounds, allyl compounds, or other compounds having one olefinic unsaturated bond. These monofunctional monomers may be included without impairing the effects of the invention. Alternatively, these monofunctional monomers may not be required.

[0031] Examples of unsaturated carboxylic acid compounds include unsaturated carboxylic acids (such as (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, fumaric acid, and maleic acid), their salts, and their anhydrides.

[0032] Examples of alkyl methacrylate compounds include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, isooctyl methacrylate, lauryl methacrylate, stearyl methacrylate, isostearyl methacrylate, and more. Isodecyl methacrylate, isomyristyl methacrylate, octadecyl methacrylate, dicyclopentyl methacrylate, tridecyl methacrylate, nonyl methacrylate, hexadecyl methacrylate, myristyl methacrylate, isoborneol methacrylate, cyclohexyl methacrylate, norborneol methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, 1-adamantyl methacrylate, 3,5,5-trimethylcyclohexyl methacrylate, and 4-tert-butylcyclohexyl(meth)acrylate.

[0033] Examples of hydroxyl-containing (meth)acrylate compounds include hydroxyalkyl (meth)acrylates such as 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, polypropylene glycol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate. Acrylates and cyclohexanediol mono(meth)acrylates), glycerol mono(meth)acrylates, 2-hydroxy-3-chloropropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-allyloxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, (poly)alkylene glycol modified (meth)acrylates (such as 2-ethylhexyl EO modified (meth)acrylates, o-phenylphenol EO modified (meth)acrylates, p-cumylphenol EO modified (meth)acrylates, and nonylphenol EO modified (meth)acrylates), and 4-hydroxybutyl acrylate glycidyl glycerol ether (HBAGE).

[0034] The content of 4-hydroxybutyl methacrylate may or may not be 1.0% to 10.0% by mass.

[0035] Examples of halogenated (meth)acrylate compounds 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-heptafluorodecyl (meth)acrylate, 2,6-dibromo-4-butylphenyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, and 2,4,6-tribromophenol 3EO (ethylene oxide) adduct ester.

[0036] Examples of ether-containing (meth)acrylate compounds include alkoxy and / or phenoxy (meth)acrylates, such as 1,3-butanediol methyl ether (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, 2-ethylhexyl carbitol (meth)acrylate, and tetramethyl (meth)acrylate. Hydrogenated furfuryl ester, cresol polyethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, p-nonylphenoxyethyl (meth) acrylate, p-nonylphenoxy polyethylene glycol (meth) acrylate, glycidyl glycerol (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, hexaethylene glycol monophenyl ether mono(meth) acrylate, diethylene glycol monobutyl ether acrylate, dipropylene glycol monomethyl ether (meth) acrylate, 3-methoxybutyl (meth) acrylate, methoxydi Ethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, methoxy polyethylene glycol (meth)acrylate (EO repeating unit number of 400, 700, etc.), 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl acrylate, ethoxyethyl acrylate, ethoxyethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, alkoxylated 2-phenoxyethyl 2-Phenoxyethyl acrylate (such as ethoxylated 2-phenoxyethyl acrylate and propoxylated 2-phenoxyethyl acrylate), alkoxylated nonylphenyl acrylate (such as ethoxylated (4) nonylphenol acrylate), 2-phenoxyethyl acrylate, p-cumylphenoxyethylene glycol acrylate, methylphenoxyethyl acrylate, ethoxylated succinic acid acrylate, ethoxylated tribromophenyl acrylate and ethoxylated nonylphenyl acrylate.

[0037] In particular, the content of phenoxyethyl (meth)acrylate may or may not be 1.0% to 15.0% by mass.

[0038] Examples of carboxyl-containing (meth)acrylate compounds include β-carboxyethyl (meth)acrylate, monoacryloyloxyethyl succinate, ω-carboxylated polycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, 2-(meth)acryloyloxypropyl hexahydrophthalate, and 2-(meth)acryloyloxypropyl tetrahydrophthalate.

[0039] The monofunctional monomer containing an amide group is preferably (meth)acrylamide, more preferably (meth)acrylamide (N,N-disubstituted (meth)acrylamide) in which the two hydrogens on the nitrogen atom of the amide group (-C(═O)NH2) are replaced by other substituents, and particularly preferably N,N-disubstituted acrylamide. Examples of N,N-disubstituted (meth)acrylamide include (meth)acryloylmorpholine, N,N-dimethyl (meth)acrylamide, diethyl (meth)acrylamide, N-hydroxyalkyl (C1 to 5) (meth)acrylamide (such as di(2-hydroxyethyl) (meth)acrylamide, di(3-hydroxypropyl) (meth)acrylamide and di(4-hydroxybutyl) (meth)acrylamide) and adducts of these N-hydroxyalkyl (C1 to 5) (meth)acrylamides with 1 to 3 mol of ethylene oxide or propylene oxide.

[0040] The monofunctional monomer containing the amide group can be 1) (methyl)acrylamide, 2) N-methyl (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, etc., in which one hydrogen atom on the nitrogen atom of the amide group (-C(=O)NH2) is replaced by other substituents, or 3) N-vinylpyrrolidone (NVP), N-vinylformamide, etc.

[0041] Examples of other (meth)acrylate compounds include benzyl acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, morpholinoethyl (meth)acrylate, trimethylsiloxyethyl (meth)acrylate, diphenyl-2-(meth)acryloyloxyethyl phosphate, 2-(meth)acryloyloxyethyl acid phosphate, caprolactone-modified 2-(meth)acryloyloxyethyl acid phosphate, 2-hydroxy-1-(meth)acryloyloxy-3-methacryloyloxypropane, acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, tricyclodecane monomethyl alcohol (meth)acrylate, (meth)acrylate dimer, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyoxy 2-Ethylhexyl diethylene glycol (meth)acrylate, aminoethyl (meth)acrylate, ethyl carbitol acrylate, ethyl diethylene glycol acrylate, dimethylaminoethyl acrylate benzyl chloride quaternary ammonium salt, tribromophenyl (meth)acrylate, 1,4-cyclohexanediethanol mono(meth)acrylate, cresol (meth)acrylate, trimethylolpropane formal (meth)acrylate, neopentyl glycol (meth) benzoate, ( 2-Methyl-2-ethyl-1,3-dioxolane-4-yl)methyl (meth)acrylate, 1-(meth)acryloylpiperidin-2-one, 2-(meth)acrylate-1,4-dioxaspiro[4,5]dec-2-methylene ester, N-(meth)acryloyloxyethyl hexahydrophthalimide, γ-butyrolactone (meth)acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, imide acrylate, vinyl (meth)acrylate and maleimide.

[0042] It may contain phosphate (meth)acrylates. (Phosphate (meth)acrylates are compounds that simultaneously possess a phosphate group and a (meth)acryloyl group in their molecule. That is, phosphate (meth)acrylates are compounds in which a "(meth)acryloyl functional group" is introduced onto one, two, or three of the three -OH groups of phosphate (P(=O)(OH)3).) Examples of styrene compounds include styrene, vinyltoluene, p-hydroxystyrene, p-chlorostyrene, p-bromostyrene, p-methylstyrene, p-methoxystyrene, p-tert-butoxystyrene, p-tert-butoxycarbonylstyrene, p-tert-butoxycarbonylstyrene, 2,4-diphenyl-4-methyl-1-pentene, and divinylbenzene.

[0043] Examples of N-vinyl compounds include N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinyl-2-caprolactam, N-vinylcarbazole, and vinylmethyloxazolidinone.

[0044] Examples of allyl compounds include allyl glycidyl glycerol ether, diallyl phthalate, triallyl trimellitate, and triallyl isocyanurate.

[0045] Other compounds having one olefinic unsaturated bond, besides those mentioned above, can be used as compounds having one olefinic unsaturated bond. Examples of such compounds include vinyl acetate, vinyl monochloroacetate, vinyl benzoate, vinyl neopentanoate, vinyl butyrate, vinyl laurate, divinyl adipate, vinyl crotonate, vinyl 2-ethylhexanoate, three-membered ring compounds (such as vinylcyclopropane, 1-phenyl-2-vinylcyclopropane, 2-phenyl-3-vinylethylene oxide, and 2,3-divinylethylene oxide), cyclic ketene acetals (such as 2-methylene-1,3-dioxane, dioxolane, 2-methylene-4-phenyl-1,3-dioxane, 4,7-dimethyl-2-methylene-1,3-dioxane, and 5,6-benzo-2-methylene-1,3-dioxane), 2-hydroxyethyl vinyl ether (HEVE), and 4-hydroxybutyl vinyl ether (HBVE).

[0046] Other monofunctional monomers included in the ink composition preferably include monomers having (meth)acrylate groups. Preferred examples of monomers having (meth)acrylate groups include isobornyl acrylate, lauryl acrylate, acrylmorpholine, 4-hydroxybutyl acrylate, ethyl carbitol acrylate, and benzyl acrylate.

[0047] When other monofunctional monomers are included in the active energy radiation-curable inkjet printing ink composition, the content of such monofunctional monomers can be from 0.1% to 70.0% by mass of the ink composition. Preferably, the content is 30.0% or more by mass, more preferably 40.0% or more by mass, and preferably 65.0% or less by mass, more preferably 60.0% or less by mass. When other monofunctional monomers are included, the content of these other monofunctional monomers in the active energy radiation-curable inkjet printing ink composition is preferably 20.0% or more by mass of the total photopolymerizable component, more preferably 30.0% or more by mass, and preferably 75.0% or less by mass, more preferably 65.0% or less by mass.

[0048] [Other multifunctional monomers (excluding amine-modified oligomers and 3-methyl-1,5-pentanediol diacrylate)] In addition to 3-methyl-1,5-pentanediol diacrylate, the ink composition may contain polyfunctional monomers, which are photopolymerizable compounds, without impairing the effects of the present invention. One type may be used alone, or two or more may be used in combination. For example, polyfunctional (meth)acrylate compounds and (meth)acrylate compounds containing vinyl ether groups may be used as polyfunctional monomers (monomers having two or more olefinic unsaturated bonds).

[0049] Polyfunctional (meth)acrylate compounds can be difunctional di(meth)acrylate compounds, trifunctional tri(meth)acrylate compounds, or polyfunctional (meth)acrylate compounds with more functional groups.

[0050] Examples of di(meth)acrylate compounds 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, butanediol di(meth)acrylate, pentylene glycol di(meth)acrylate, neopentylene glycol di(meth)acrylate, PO-modified neopentylene glycol di(meth)acrylate, and hydroxypentylene glycol di(meth)acrylate. Acrylates, hydroxypentanoyl hydroxypentanoic acid dicaprolactone di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, EO-modified 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 Acrylates, 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, dimethyl 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, tricyclodecanediethanol di(meth)acrylate, tricyclodecanediethanol dicaprolactone di(meth)acrylate, cyclohexanediethanol di(meth)acrylate, dicyclopentyl di(meth)acrylate, bisphenol A tetraethylene oxide adduct di(meth)acrylate, bisphenol F tetraethylene oxide adduct di(meth)acrylate, bisphenol S tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A tetraethylene oxide adduct Di(meth)acrylates, hydrogenated bisphenol F tetraethylene oxide adduct di(meth)acrylates, hydrogenated bisphenol A di(meth)acrylates, hydrogenated bisphenol F di(meth)acrylates, bisphenol A tetraethylene oxide adduct dicaprolactone di(meth)acrylates, bisphenol F tetraethylene oxide adduct dicaprolactone di(meth)acrylates, and di(meth)acrylates of polyols (such as glycerol, pentaerythritol, dimeric glycerol, ditrimethylene glycol, and dipentaerythritol).

[0051] It may or may not contain 1.0% to 10.0% by weight of PO-modified neopentyl glycol di(meth)acrylate and 1.0% to 15.0% by weight of 1,6-hexanediol di(meth)acrylate.

[0052] Examples of tri(meth)acrylate compounds include glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tricaprolactone tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolhexane tri(meth)acrylate, trimethylol octane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and their 3EO (ethylene oxide) modified, 6EO modified, and 9EO modified products (such as 3EO modified trimethylolpropane tri(meth)acrylate, 3EO modified trimethylolethane tri(meth)acrylate, and 3EO modified trimethylolhexane tri(meth)acrylate).

[0053] Examples of tetrafunctional or higher (meth)acrylate compounds include monomers with more than four functionalities, such as trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tetracaprolactone tetra(meth)acrylate, dipropylene glycol tetra(meth)acrylate, ditrimethylene glycol tetra(meth)acrylate, ditrimethylene glycol tetracaprolactone tetra(meth)acrylate, ditrimethylene ethane tetra(meth)acrylate, ditrimethylene butane tetra(meth)acrylate, ditrimethylene hexane tetra(meth)acrylate, ditrimethylene octane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, and tripentaerythritol polyalkylene oxide hepta(meth)acrylate.

[0054] Examples of (meth)acrylate compounds containing vinyl ether groups include 2-vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 1-methyl-3-vinyloxypropyl (meth)acrylate, 1-vinyloxymethylpropyl (meth)acrylate, 2-methyl-3-vinyloxypropyl (meth)acrylate, 3-methyl-3-vinyloxypropyl (meth)acrylate, 1,1-dimethyl-2-vinyloxyethyl (meth)acrylate, 3-vinyloxybutyl (meth)acrylate, 1-methyl-2-vinyloxypropyl (meth)acrylate, 2-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 5-vinyloxypentyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, and 4-vinyloxymethylcyclohexylmethyl (methyl)acrylate. Acrylates, 3-vinyloxymethylcyclohexyl methacrylate, 2-vinyloxymethylcyclohexyl methacrylate, p-vinyloxymethylphenyl methacrylate, m-vinyloxymethylphenyl methacrylate, o-vinyloxymethylphenyl methacrylate, 2-(vinyloxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxy)propyl (meth)acrylate, 2-(vinyloxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)ethyl (meth)acrylate, and 2-(vinyloxyisopropoxy)ethyl (meth)acrylate.

[0055] The content of the multifunctional monomer in the active energy radiation-curable inkjet ink composition is preferably 10.0% or more by mass, more preferably 20.0% or more by mass, and preferably 70.0% or less by mass, more preferably 60.0% or less by mass. The content of the multifunctional monomer in the active energy radiation-curable inkjet ink composition is preferably 15.0% or more by mass, more preferably 25.0% or more by mass, and preferably 80.0% or less by mass, more preferably 70.0% or less by mass.

[0056] [Oligomers other than amine-modified oligomers] Without impairing the effects of the invention, the ink composition of the present invention may contain oligomers other than amine-modified oligomers or may not contain oligomers other than amine-modified oligomers.

[0057] Examples of oligomers other than amine-modified oligomers include polyurethane acrylate oligomers, epoxy acrylate oligomers, and silicone acrylate oligomers.

[0058] [pigment] Ink compositions may or may not contain pigments. Pigments are components added to impart tinting strength, hiding power, etc., to the ink composition. Examples include coloring pigments, white pigments, and metallic powders. Examples of such pigments may include, but are not specifically limited to, the following organic and / or inorganic pigments commonly used in ink compositions.

[0059] Examples of pigments include organic pigments such as dye lake pigments, azo, benzimidazolone, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigo, thioindigo, perylene, perylene ketone, diketopyrrolopyrrole, isoindolinone, nitro, nitroso, flavanone, quinophthalone, pyranone, and indanone pigments; as well as various inorganic pigments.

[0060] Preferred examples of these pigments include yellow pigments such as diazo yellow (pigment yellow 12, pigment yellow 13, pigment yellow 14, pigment yellow 17 and pigment yellow 1), Hansa yellow, pigment yellow 150 and pigment yellow 155; magenta pigments such as Brilliant Carmine 6B, Lake Red C, Permanent Red, Quinacridone, Pigment Red 122 and Pigment Red 254; cyan pigments such as Phthalocyanine Blue, Phthalocyanine Green, Basic Blue and Pigment Blue 15:4; colored pigments (including non-color colored pigments such as white and black), such as titanium dioxide (e.g., Pigment White 6), zinc oxide, iron oxide red, antimony red, cadmium yellow, cobalt blue, iron blue, ultramarine, iron black, chromium oxide green, carbon black (e.g., Pigment Black 7) and graphite; and metallic powders such as aluminum powder and copper powder.

[0061] The pigment content in an ink composition varies depending on the type of pigment and the desired degree of coloration. For example, the pigment content, by mass, can be, but is not specifically limited to, about 1.0% to 30.0% of the total ink composition. When preparing a colored ink composition, another color pigment or dye can be used as a complementary color, or another color ink composition can be added.

[0062] In this invention, when the pigment contains carbon black, the carbon black content in the pigment is not particularly limited and can be freely set within a range of greater than 0% to 100% of the total pigment by mass. For example, the content is 30.0% or more by mass, preferably 50.0% or more by mass, more preferably 80.0% or more by mass, and even more preferably 100% by mass.

[0063] [Pigment Dispersant] The ink composition may contain a pigment dispersant for dispersing pigments. The pigment dispersant is preferably a polymer-based pigment dispersant, and more preferably a pigment dispersant containing a basic group. Examples of pigment dispersants containing basic groups include polymer pigment dispersants, such as polyester pigment dispersants, acrylic pigment dispersants, urethane pigment dispersants, and carbodiimide pigment dispersants; and anionic surfactants.

[0064] The polymer-based pigment dispersant can be, but is not specifically limited to, a linear polymer having a block or graft structure and having at least one end (at one or each end) of the main chain containing a portion of a basic group that has an affinity for pigments. The polymer-based pigment dispersant can contain 2 to 3000 basic groups per molecule and has a number average molecular weight of 1000 to 1000000.

[0065] The amine value of the pigment dispersant is preferably 10 mg / KOH / g or higher, more preferably 16 mg / KOH / g or higher, and more preferably 100 mg / KOH / g or lower, more preferably 80 mg / KOH / g or lower, and even more preferably 70 mg / KOH / g or lower. The amine value refers to the total amount of free base and alkali, expressed in milligrams of potassium hydroxide, and is equivalent to the amount of hydrochloric acid required to neutralize 1 gram of sample.

[0066] In some cases, the ink composition preferably contains two or more pigment dispersants with different amine values. That is, when a pigment dispersant with an amine value less than a certain value is mixed with a pigment dispersant with an amine value equal to or greater than a certain value, the dispersion stability of the pigment in the ink composition can be improved. Preferably, a combination of pigment dispersants with an amine value less than 30 mg KOH / g and pigment dispersants with an amine value greater than 30 mg KOH / g can be used.

[0067] Specific examples of pigment dispersants (preferably pigment dispersants containing basic groups) include the following examples (1) to (17).

[0068] (1) The reaction product of the amino and / or imino groups of a polyamine compound (e.g., a poly-lower alkyleneamine, such as polyallylamine, polyethyleneamine or polyethylene polyimide) with at least one selected from polyester, polyamide and polyesteramide groups having a free carboxyl group (see Japanese patent application pending publication number 2001-59906). (2) The reaction products of low molecular weight amino compounds (such as poly(lower) alkylene imines or methylaminodipropylamine) with polyesters having free carboxyl groups (see Japanese patent applications pending publication numbers 54-37082 and 1-311177). (3) The reaction product formed by the reaction of the isocyanate group of a polyisocyanate compound with an alcohol (such as methoxy polyethylene glycol) or a polyester having one hydroxyl group (such as caprolactone polyester), a compound having two or three isocyanate reactive functional groups, and an aliphatic or heterocyclic hydrocarbon compound having an isocyanate reactive functional group and a tertiary amino group (see Japanese patent application pending with publication number 2-612). (4) Compounds formed by reacting acrylate polymers with alcohol hydroxyl groups with polyisocyanate compounds and hydrocarbons with amino groups; (5) The reaction product formed by adding polyether chains to a low molecular weight amino compound; (6) The reaction product formed by the reaction of a compound having an isocyanate group with a compound having an amino group (see Japanese patent application pending publication number 4-210220). (7) The reaction product formed by reacting a polyepoxide with a linear polymer having a free carboxyl group and an organic amine compound having a secondary amino group (see Japanese patent application pending publication number 9-87537). (8) The reaction product of a polycarbonate compound having a functional group at one end that can react with an amino group and a polyamine compound (see Japanese patent application pending publication number 9-194585). (9) A copolymer of the following substances: at least one selected from methacrylates and acrylates (such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, stearyl methacrylate, benzyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, stearyl acrylate and benzyl acrylate); at least one polymerizable monomer containing a basic group (such as acrylamide, methacrylamide, N-hydroxymethylamide, vinylimidazole, vinylpyridine and monomers having an amino and polycaprolactone backbone); and at least one selected from styrene, styrene derivatives and other polymerizable monomers (see Japanese Patent Application Publication No. 1-164429 pending); (10) Carbodiimide pigment dispersants containing basic groups (see international application with publication number 2004 / 000950). (11) A block copolymer consisting of blocks having basic groups (such as tertiary amino or quaternary ammonium salts) and blocks without functional groups (see Japanese patent application pending publication number 2005-55814). (12) Pigment dispersant obtained by Michael addition reaction of polyallylamine with polycarbonate compound (see Japanese patent application pending publication number 9-194585). (13) A carbodiimide compound having at least one polybutadiene chain and at least one basic nitrogen-containing group (see Japanese patent application pending with publication number 2006-257243). (14) A carbodiimide compound having at least one side chain containing an amide group and at least one basic nitrogen-containing group in the molecule (see Japanese patent application pending with publication number 2006-176657). (15) Polyurethane compounds containing structural units having ethylene oxide chains and propylene oxide chains and containing amino groups quaternized by a quaternizing agent (see Japanese patent application pending publication number 2009-175613). (16) A compound obtained by reacting an isocyanate group in an isocyanate compound having an isocyanurate ring with an active hydrogen group in a compound having an active hydrogen group and a carbazole ring and / or an azobenzene skeleton, wherein the number of carbazole ring and azobenzene skeleton is 15% to 85% of the total number of isocyanate groups derived from isocyanate compounds having an isocyanurate ring and the total number of urethane bonds and urea bonds formed by the reaction of the isocyanate group with the active hydrogen group in the compound molecule (see Japanese patent application pending with publication number 2010-107965). (17) A graft copolymer in which a polyether or polyester side chain is introduced into an acrylate polymer having, for example, an amino group.

[0069] Pigment dispersants are also commercially available. Examples of commercially available pigment dispersants include Lubrizol's SOLSPERSE series, BYK Chemie's Disperbyk and BYKJET series, BASF's EFKA series, and Ajinomoto Fine-Techno Co., Inc.'s AJISPER series.

[0070] Examples of the SOLSPERSE series include SOLSPERSE 11200, SOLSPERSE 13240, SOLSPERSE 13650, SOLSPERSE 13940, SOLSPERSE 16000, SOLSPERSE 17000, SOLSPERSE 18000, SOLSPERSE 20000, SOLSPERSE 24000, SOLSPERSE 24000SC, SOLSPERSE 24000GR, SOLSPERSE 2600, SOLSPERSE 28000, SOLSPERSE 31845, SOLSPERSE 32000, SOLSPERSE 32500, SOLSPERSE 32550, SOLSPERSE 32600, SOLSPERSE 33000, SOLSPERSE 34750, SOLSPERSE 35100, SOLSPERSE 35200, SOLSPERSE 37500, SOLSPERSE 38500, SOLSPERSE 39000, SOLSPERSE 56000, SOLSPERSE 71000, SOLSPERSE 73000, and SOLSPERSE 74000.

[0071] Examples of the Disperbyk series include Disperbyk-101, Disperbyk-108, Disperbyk-109, Disperbyk-112, Disperbyk-116, Disperbyk-130, Disperbyk-140, Disperbyk-142, Disperbyk-145, Disperbyk-161, Disperbyk-162, Disperbyk-163, Disperbyk-164, Disperbyk-166, Disperbyk-167, Disperbyk-168, Disperbyk-180, Disperbyk-182, Disperbyk-183, Disperbyk-185, Disperbyk-184, Disperbyk-2000, Disperbyk-2001, Disperbyk-2008, Disperbyk-2020, Disperbyk-2050, Disperbyk-2070, Disperbyk-2150, and Disperbyk-2155.

[0072] Examples of the BYKJET series include BYKJET-9131, BYKJET-9132, BYKJET-9133, BYKJET-9142, BYKJET-9150, BYKJET-9151, BYKJET-9152, BYKJET-9170, BYKJET-9171, BYKJET-9175, and BYKJET-9177.

[0073] Examples of the EFKA series include EFKA 4008, EFKA 4046, EFKA 4047, EFKA 4015, EFKA 4020, EFKA 4050, EFKA 4055, EFKA 4060, EFKA 4080, EFKA 4300, EFKA 4330, EFKA 4400, EFKA4401, EFKA 4402, EFKA 4403, EFKA 4500, EFKA 4510, EFKA 4530, EFKA 4800, EFKA PX 4701 and EFKA PX 4703.

[0074] Examples of the AJISPER series include AJISPER PB-711, AJISPER PB-821, and AJISPER PB-822.

[0075] Examples of pigment dispersants with an amine value of 30 mg KOH / g or higher include SOLSPERSE 24000 (41.6 mg KOH / g), SOLSPERSE 32000 (31.2 mg KOH / g), SOLSPERSE 33000 (43 mg KOH / g), SOLSPERSE 56000 (39 mg KOH / g), SOLSPERSE 71000 (75 mg KOH / g), SOLSPERSE 73000 (80 mg KOH / g), SOLSPERSE 74000 (81 mg KOH / g), Disperbyk-108 (71 mg KOH / g), Disperbyk-180 (94 mg KOH / g), Disperbyk-2008 (66 mg KOH / g), Disperbyk-2050 (31 mg KOH / g), Disperbyk-2155 (48 mg KOH / g), and EFKA. 4300 (57 mgKOH / g), EFKA 4401 (48 to 52 mgKOH / g), EFKA PX 4701 (40 mgKOH / g) and EFKA PX 4703 (56 mgKOH / g).

[0076] Examples of pigment dispersants with amine values ​​less than 30 mg KOH / g include SOLSPERSE 39000 (26 mg KOH / g), Disperbyk-163 (10 mg KOH / g), Disperbyk-168 (11 mg KOH / g), BYKJET-9151 (18 mg KOH / g), BYKJET-9152 (27 mg KOH / g), AJISPER PB-821 (11.2 mg KOH / g), and AJISPER PB-822 (18.2 mg KOH / g).

[0077] When a pigment dispersant with an amine value less than 30 mg KOH / g is mixed with a pigment dispersant with an amine value of 30 mg KOH / g or more, or with a pigment dispersant with an amine value less than 30 mg KOH / g, the amine value is preferably 10 mg KOH / g or more, and more preferably 20 mg KOH / g or more. For pigment dispersants with an amine value of 30 mg KOH / g or more, the amine value is more preferably 100 mg KOH / g or less, more preferably 80 mg KOH / g or less, and even more preferably 70 mg KOH / g or less. The amine value difference between a pigment dispersant with an amine value less than 30 mg KOH / g and a pigment dispersant with an amine value of 30 mg KOH / g or more can be 1 mg KOH / g or more.

[0078] When the ink composition contains a pigment dispersant, the pigment dispersant content is preferably 10.0 to 100 parts by weight of pigment per 100 parts by weight. More preferably, the pigment dispersant content is 15.0 parts by weight or more, more preferably 70.0 parts by weight or less, even more preferably 65.0 parts by weight or less, and most preferably 60.0 parts by weight or less. The pigment dispersant content, by weight, is preferably 0.1% or more of the entire ink composition, more preferably 0.15% or more, even more preferably 0.2% or more, and preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.5% or less. When a pigment dispersant (α) with an amine value less than 30 mg KOH / g is used in combination with a pigment dispersant (β) with an amine value of 30 mg KOH / g or more, the mass ratio of component α to component β is preferably (but not specifically limited to) in the range of α:β = 10:1 to 10:15.

[0079] [Photopolymerization initiator] The ink composition of the present invention may contain a photopolymerization initiator. Examples of photopolymerization initiators include anisole-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-keto alcohol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, triazine-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators. Among these, triazine-based photopolymerization initiators and acylphosphine oxide-based photopolymerization initiators are preferred from the perspective of good photocurability. These photopolymerization initiators can be used alone or in combination of two or more. For example, two acylphosphine oxide-based photopolymerization initiators can be used in combination.

[0080] Specific examples of photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide, benzophenone, diethylthioxanthanone, 2-methyl-1-(4-methylthio)phenyl-2-morpholinylpropane-1-one, 4-benzoyl-4'-methyldiphenyl sulfide, 1-chloro-4-propoxythioxanthanone, isopropylthioxanthanone, and 2-hydroxy-2-methyl -1-Phenylacetyl-1-one, 1-hydroxycyclohexylphenyl one, bis-2,6-dimethoxybenzoyl-2,4,4-trimethylpentylphosphine oxide, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one, 2,2-dimethyl-2-hydroxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, (2,4,6-trimethylbenzyl)diphenylphosphine oxide, and 2-benzyl-2-dimethylamino-1-(morpholinylphenyl)butane-1-one.

[0081] The content of photopolymerization initiator in the ink composition can be set according to the required curing rate of the photocurable resin composition. For reference, it is preferably more than 1.0% by weight of the whole ink composition, more preferably more than 3.0% by weight, and preferably less than 18.0% by weight, more preferably less than 16.0% by weight.

[0082] [Other optional components] The ink compositions of the present invention may contain other optional components. Examples of other optional components include sensitizers, polymerization inhibitors, surfactants (leveling agents), solvents, surface tension modifiers, non-reactive resins, ultraviolet absorbers, and antioxidants.

[0083] [Sensitizer] From the perspective of improving photocurability, ink compositions may contain sensitizers. Sensitizers can be used alone, or two or more sensitizers can be used in combination.

[0084] Examples of sensitizers include anthracene sensitizers such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene; and thioxanthone sensitizers such as 2,4-diethylthioxanthone, 2,4-diethylthioxanthone-9-one, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. Commercially available examples of the above sensitizers include anthracene sensitizers marketed under the trade names “DBA” and “DEA” (Kawasaki Kasei Chemicals Ltd.), and thioxanthone sensitizers marketed under the trade names “DETX” and “ITX” (Lambson Ltd.).

[0085] When the ink composition contains a sensitizer, from the perspective of preventing excessive addition, the sensitizer content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, in 100 parts by mass of the total amount of photopolymerizable compounds (including amine-modified oligomers, monofunctional monomers containing alicyclic skeletons that form polymers with a Tg of 10°C to 60°C during polymerization, 3-methyl-1,5-pentanediol diacrylate, acrylamide, and other polymerizable compounds). The sum of the photopolymerization initiator content and the sensitizer content is preferably 2.0 to 15.0 parts by mass in 100 parts by mass of the total amount of photopolymerizable compounds.

[0086] [Polymerization inhibitor] The ink composition may contain a polymerization inhibitor. The polymerization inhibitor can prevent the ink composition from polymerizing during storage and can inhibit the thickening of the ink composition.

[0087] Examples of polymerization inhibitors include phenolic compounds (including quinones, such as tert-butylhydroxytoluene), tocopherol acetate, nitrosamines, benzotriazoles, and hindered amines. Among these, quinones and nitrosamines are more preferred.

[0088] The content of polymerization inhibitor in the active energy radiation-curable inkjet ink composition is appropriately set according to the type of polymerization inhibitor. For quinone compounds, the content is about 0.1 to 1.0 parts by mass per 100 parts by mass of the total photopolymerizable component.

[0089] Surfactants (leveling agents) Depending on the printhead type of the inkjet printer used for printing, the ink composition may contain surfactants as leveling agents. Known surfactants may be included, without particular limitation. Examples of surfactants include nonionic surfactants, cationic surfactants, anionic surfactants, and betaine surfactants. Specific examples of surfactants include silicone-based surfactants (such as polyether-modified silicone oils, polyester-modified polydimethylsiloxanes, and polyester-modified methylalkyl polysiloxanes), fluoropolymer surfactants, and acetylene-based surfactants. These surfactants may be used alone or in combination of two or more.

[0090] Examples of silicone-based surfactants include BYK-307, BYK-315N, BYK-331, BYK-333, BYK-347, BYK-348, BYK-349, BYK-345, BYK-377, BYK-378, BYK-3455, and BYK-UV3500 (BYK Chemicals).

[0091] Examples of fluorinated surfactants include F-410, F-444, F-553 (DIC Corp.), FS-65, FS-34, FS-35, FS-31, and FS-30 (DuPont de Nemours, Inc.).

[0092] Examples of acetylene-based surfactants include Dynol 607, Dynol 609, Olfine E1004, Olfine E1010, Olfine E1020, Olfine PD-001, Olfine PD-002W, Olfine PD-004, Olfine PD-005, Olfine EXP.4001, Olfine EXP.4200, Olfine EXP.4123, Olfine EXP.4300 (Nissin Chemical Industry Co., Ltd.), Surfynol 104E, Surfynol 104H, Surfynol 104A, Surfynol 104BC, Surfynol 104DPM, Surfynol 104Pa, Surfynol 104PG-50, and Surfynol... 420, Surfynol 440 and Surfynol 465 (Evonik).

[0093] From the perspective of reducing the surface tension of the ink composition and enhancing the ejection stability of the inkjet head, the surfactant content in the ink composition is preferably 0.005% or more by mass, more preferably 0.01% or more by mass. From the perspective of suppressing bubbles in the ink composition generated during the mixing process and enhancing ejection stability, it is preferably 1.5% or less by mass, more preferably 1.0% or less by mass.

[0094] When a surfactant is included as a leveling agent, the surfactant content is preferably adjusted such that the surface tension of the ink composition at 25°C is 20 to 36 mN / m. In active energy radiation-curable inkjet ink compositions, the surfactant content is more preferably 0.1% to 1.5% by mass.

[0095] [solvent] The ink compositions of the present invention may or may not contain water or organic solvents. As used herein, the term "organic solvent" refers to a non-reactive organic solvent, which, unlike reactive organic solvents, is not a component that forms a coating film through curing.

[0096] [Physical Properties and Applications of Ink Compositions] The active energy ray curable inkjet ink composition of the present invention can be printed using an inkjet device and exhibits excellent performance in terms of LED curability and head ejection stability. Furthermore, the printed layer obtained by curing the active energy ray curable inkjet ink composition exhibits excellent adhesion to the target printing substrate, flexibility of the printed film, and image quality, and also has low surface tack and odor.

[0097] [Printing Method] The ink composition of the present invention can be used for printing with an inkjet printer. The inkjet printer system that can be used can be, but is not specifically limited to, a line head system (single-pass system) or a serial head system (multi-pass system). The inkjet printer can also be a continuous inkjet printer. In this case, the conductivity of the ink composition can be adjusted by further adding conductive additives.

[0098] The ink composition is supplied to the printhead of the inkjet printer, and the ink composition is ejected from the printhead onto the target printing substrate. The ejection of the ink composition from the printhead onto the substrate (printed image) can be performed in such a way that the film thickness is, for example, 1 to 60 µm.

[0099] The ink composition applied to the substrate is cured by exposure to ultraviolet light, electron beams, or visible light emitted from light-emitting diodes (LEDs) and various lamps and electrodes. From an environmental perspective, it is preferable to use light-emitting diodes (LEDs) that produce ultraviolet light with emission peak wavelengths in the range of 350 to 420 nm as the light source.

[0100] [Target Printing Substrate] There are no particular limitations on the target printing substrate, as long as it is a substrate to which conventionally known active energy ray-curable inkjet ink compositions can be applied. Examples of substrates include plastics, paper, capsules, gels, metal foils, glass, wood, and cloth. The active energy ray-curable inkjet ink composition of the present invention can provide an effect that makes it unlikely for photopolymerization initiators to migrate, even when a substrate formed of any material is used as the printing target. Examples of plastics forming the substrate include those selected from polyester-based polymers (such as polyethylene terephthalate (PET) and polyethylene naphthalate), cellulose-based polymers (such as diacetyl cellulose and triacetyl cellulose (TAC)), polycarbonate polymers, polyacrylic acid polymers (such as polymethyl methacrylate), vinyl chloride polymers (such as polyvinyl chloride (PVC)), polyolefin polymers (such as polyethylene, polypropylene, polyolefin polymers having cyclic or norbornene structures, and ethylene-propylene copolymers), polyamide polymers (such as nylon and aromatic polyamide polymers), polystyrene polymers (such as polystyrene and acrylonitrile-styrene copolymers), polyimide polymers, polysulfone polymers, polyethersulfone polymers, polyetherketone polymers, polyphenylene sulfide polymers, polyvinyl alcohol polymers, polyvinylidene chloride polymers, polyvinyl butyral polymers, polyarylate polymers, polyoxymethylene polymers, polyepoxy polymers, and blends of these polymers.

[0101] Example The invention will be described in more detail below with reference to embodiments, but the description of the embodiments should not be construed as limiting the scope of the invention.

[0102] The following describes the materials used to prepare the ink compositions.

[0103] Pigments PB15:4: Pigment Blue 15:4 PR122: Pigment Red 122 PY150: Pigment Yellow 150 P.Bk.7: Pigment Black 7 (Carbon Black) Pigment dispersants Dispersant 1: EFKA PX 4701 (amine value: 40 mg KOH / g) (BASF) Dispersant 2: SOLSPERSE 56000 (amine value: 39 mgKOH / g) (Lubrizol) Dispersant 3: SOLSPERSE 24000 (amine value: 24 mgKOH / g) (Lubrizol) Dispersant 4: BYKJET-9151 (amine value: 18 mg KOH / g) (BYK Chemicals) Amine-modified oligomer: Agisyn 008 (DSM Coatings & Resins) TMCHA: 3,3,5-Trimethylcyclohexyl acrylate CHA: Cyclohexyl acrylate MPDA: 3-Methyl-1,5-pentanediol diacrylate (EO)TMPTA: Ethoxylated trimethylolpropane triacrylate Photopolymerization initiators TPO: Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide TPO-L: Ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide DETX: 2,4-Diethylthioxanthone <surfactants> BYK-377: Silicon-based surfactant (BYK Chemicals) <Polymerization inhibitors> MEHQ: Hydroquinone monomethyl ether The ink compositions in the examples and comparative examples were prepared according to the composition formulations given in Tables 1, 2, 3, and 4. Specifically, a mixture of compositions containing pigments and pigment dispersants was stirred to prepare a pigment dispersion. Monomers, oligomers, photopolymerization initiators, etc., were added to the obtained pigment dispersion, and the mixture was stirred to prepare the ink composition.

[0104] The ink compositions prepared for each example and comparative example were evaluated for the following items, and the evaluation results are shown in Tables 1, 2, 3 and 4.

[0105] (Head ejection capability) The inkjet recording device equipped with inkjet nozzles and each UV-curable inkjet ink composition were placed at an ambient temperature of 25°C for 24 hours to allow the temperature of both the inkjet recording device and the UV-curable inkjet printing ink composition to reach 25°C. Subsequently, the UV-curable inkjet printing ink composition was continuously sprayed onto polyvinyl chloride (PVC) at 25°C for 1 minute, and then the printhead ejection stability was evaluated according to the following criteria: ○: The ink composition is ejected stably without printing interference; △: Despite some printing interference, the ink composition was ejected almost stably; ×: Printing is disrupted, or the ink composition cannot be ejected stably.

[0106] (LED curability) The inkjet recording device and each UV-curable inkjet printing ink composition were placed at an ambient temperature of 25°C for 24 hours to allow the temperature of the inkjet recording device and the UV-curable inkjet printing ink composition to reach 25°C. Subsequently, the UV-curable inkjet printing ink composition was continuously printed on a polyvinyl chloride (PVC) sheet at 25°C. Afterwards, a UV-LED lamp manufactured by Phoseon Technology was used at 180 mJ / cm². 2 The ink composition was cured using cumulative UV light exposure, with a 2 cm distance maintained between the lamp and the ink coating surface. The cured coating was wiped with a cotton swab, and the curing performance was evaluated based on the degree of removal. The degree of removal was visually determined according to the following evaluation criteria: ○: No removal was observed; ×: Removal was observed.

[0107] (Seamless fit) The ink compositions prepared in each example and comparative example were applied to the surfaces of PVC (polyvinyl chloride sheet, product name: PVC80-P-11k White, manufactured by Lintec Corporation), banner (polyvinyl chloride-coated polyester fabric (with a surface structure reflecting the irregularity of the fabric, unlike PVC sheet)), PET (polyethylene terephthalate, product name: E5100, manufactured by Toyobo Co., Ltd.) and coated paper (product name: OK Top Coat, manufactured by Oji Paper Co., Ltd.) using a commercially available inkjet printer, and then irradiated with ultraviolet light to prepare a cured coating film. The cured coating film formed on the substrate was cross-cut with a cutting knife to form 100 squares of cured coating film. Transparent tape (Cellotape (registered trademark), Nichiban Co., Ltd.) was then applied to the cross-cut areas and peeled off. The evaluation is based on the number of squares that remain on the substrate and do not adhere to the transparent tape, thus requiring peeling. The total number of squares obtained from the cross-cut is recorded as the denominator, and the number of unpeeled squares is recorded as the numerator.

[0108] In Table 1, "100 / 100" indicates that none of the sheets have peeled off and all sheets remain on the substrate, which means that the adhesion is good.

[0109] (Flexibility) An inkjet printing ink composition for UV curing was printed onto polyethylene terephthalate (PET) sheets using an inkjet recording device. After UV irradiation, a cured coating was formed. The printed sample was folded 180° and evaluated visually according to the following criteria: ○: No linear cracks or micro-cracks appeared in the coating during folding; △: Microcracks are generated during folding; ×: Line cracks appear when folding (long and large cracks appear at the folding point when folding).

[0110] (Image quality) The UV-curable inkjet printing ink compositions prepared in the various examples and comparative examples were printed onto the surface of coated paper (PA-T1 8LK Blue, manufactured by Lintec Corporation) using an inkjet recording device to form a solid color image. The images were then irradiated with UV light to form a cured coating. The degree of filling of the solid color areas of the cured coating on the printed matter was visually evaluated according to the following evaluation criteria: Evaluation criteria ○: The solid color areas are completely filled, with almost no stripe effect; ×: Obvious stripes are visible overall.

[0111] (Surface adhesion) Using a No. 4 rod coater, the UV-curable ink compositions for inkjet printing prepared in each example and comparative example were coated onto the corresponding surfaces of two polyethylene terephthalate (PET) films, and then cured by UV irradiation.

[0112] Temporarily overlap the cured coatings on the surfaces of two PET films, and manually peel them off after 30 seconds. Evaluate the adhesion based on the feel of the film upon peeling using the following criteria: ○: No viscosity was observed; ×: Viscosity was observed.

[0113] (Coating odor) The UV-curable ink compositions for inkjet printing prepared in each example and comparative example were applied to the surface of polyvinyl chloride (PVC) using a No. 6 bar coater, and then cured by UV irradiation.

[0114] The cured coating was cut into 8 cm × 12 cm pieces. Each piece was placed in a 24 cm × 34 cm resealable zippered bag, which was immediately sealed. The bag was then kept at 25°C for 1 hour before being opened. The odor at the opening was smelled and evaluated according to the following criteria: ○: No odor detected; △: A slight odor was detected; ×: A distinct odor was detected.

[0115] Ten people gave the same evaluation, and the evaluation result with the most people was used as the assessment result for the odor of the coating.

[0116] [Table 1]

[0117] [Table 2]

[0118] [Table 3]

[0119] [Table 4]

[0120] According to each embodiment described in Tables 1 to 3, an active energy ray curable inkjet composition with excellent head ejection capability and LED curability can be obtained. Furthermore, a coating with excellent adhesion, flexibility, and image quality, no surface tack, and minimal odor can be obtained. However, in each of Examples 20 to 22, when the content of the monofunctional acrylate (such as benzyl acrylate, tetrahydrofurfuryl acrylate, or isobornyl acrylate) as an odor source was 5% by mass, no odor was perceived. In each of Examples 23 to 25, when the content of the monofunctional acrylate was 10% by mass, a slight odor was perceived.

[0121] In contrast, among the comparative examples described in Table 4, some active energy ray curable inkjet ink compositions exhibited poor head ejection capability or LED curing performance. Furthermore, some coatings showed poor adhesion, flexibility, or image quality, or poor surface tack or coating odor.

[0122] Practicality of work The active energy ray curable ink composition of the present invention provides an active energy ray curable ink composition with excellent head ejection capability and LED curability. Furthermore, regardless of the type of target printing substrate, a coating with excellent adhesion, flexibility, and image quality, no surface tack, and minimal odor can be obtained.

Claims

1. An ink composition for inkjet printing that is cured by active energy rays, satisfying the following conditions (A) to (D): (A) The content of amine-modified oligomers, by mass, is 1.0% to 20.0% of the total solids. (B) The content of monofunctional monomers containing an alicyclic skeleton that form a polymer with a Tg of 10°C to 60°C during polymerization accounts for more than 16.0% by mass of the total solids content. (C) The content of 3-methyl-1,5-pentanediol diacrylate is from 8.0% to 25.0% by mass of the total solids content, and (D) The content of acrylomorpholine is 3.0% to 15.0% of the total solids by mass.

2. The active energy ray curable ink composition for inkjet printing according to claim 1, wherein, The content of the amine-modified oligomer is 2.0% to 15.0% of the total solids by mass.

3. The active energy ray curable ink composition for inkjet printing according to claim 1 or 2, wherein, The content of the amine-modified oligomer is 4.0% to 13.0% of the total solids by mass.

4. The active energy ray curable ink composition for inkjet printing according to any one of claims 1 to 3, wherein, The content of the monofunctional monomer containing an alicyclic skeleton that forms a polymer with a Tg of 10°C to 60°C during polymerization accounts for more than 18.0% by mass of the total solids content.

5. The active energy ray curable ink composition for inkjet printing according to any one of claims 1 to 4, wherein, The content of 3-methyl-1,5-pentanediol diacrylate is 10.0% to 20.0% of the total solids by mass.

6. The active energy ray curable ink composition for inkjet printing according to any one of claims 1 to 5, wherein, The content of acrylomorpholine is 5.0% to 10.0% of the total solids by mass.

7. The active energy ray curable ink composition for inkjet printing according to any one of claims 1 to 6, wherein, The monofunctional monomer containing an alicyclic skeleton that forms a polymer with a Tg of 10°C to 60°C during polymerization is tert-butylcyclohexyl acrylate.

8. The active energy ray curable ink composition for inkjet printing according to any one of claims 1 to 7, wherein, The contents of benzyl acrylate, tetrahydrofurfuryl acrylate and isobornyl acrylate are all less than 5.0% of the total solids by mass.

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