Ink composition, ink set, printed material, inkjet recording device, recording method, and method for manufacturing printed material

Abstract

This invention provides an ink composition that possesses the properties required for active energy ray curable ink compositions, even if it contains a polymerization initiator that is not a candidate for inclusion as a substance of very high concern under the REACH Regulation. [Solution] An active energy ray curable ink composition ejected by an inkjet method, comprising a polymerizable compound and a polymerization initiator, wherein the polymerization initiator comprises a specific acylphosphine oxide-based polymerization initiator A that is not a candidate for inclusion as a substance of very high concern under the REACH Regulation, and a polymerization initiator B that differs from acylphosphine oxide-based polymerization initiator A in that it contains a polycyclic structure, and the polymerizable compound comprises a polymerizable group-containing modified polysiloxane compound.

Description

[Technical Field]

[0001] The present invention relates to an ink composition, an ink set, a printed material, an inkjet recording device, a recording method, and a method for manufacturing a printed material. [Background technology]

[0002] In recent years, there has been a trend towards small-batch, high-mix printing of printed materials, and inkjet printing, an on-demand printing method, is attracting attention as an alternative to the conventional offset printing method. Compared to the conventional offset printing method, inkjet printing is simpler and offers advantages such as cost-effectiveness and energy savings.

[0003] Among these inkjet printing methods, there is one that uses an active energy ray curing ink composition that hardens when exposed to ultraviolet light, electron beams, or other active energy rays. Because active energy ray curing ink compositions are fast-drying, ink bleeding can be prevented even when printing on substrates that do not absorb ink or absorb very little ink, such as plastics, glass, and coated paper.

[0004] For example, Patent Document 1 describes a technology relating to an energy-ray curable inkjet ink composition that allows for stretching of the printed film after curing, and which contains a monomer (polymerizable compound) having an ethylenic double bond and an acylphosphine oxide-based initiator such as diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO).

[0005] Patent Document 1 describes that this energy ray curable inkjet ink composition has excellent stretchability of the printed film, as well as excellent curability, adhesion, and continuous ejection properties. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-299057 [Overview of the project] [Problems that the invention aims to solve]

[0007] Recently, there has been a need to develop active energy ray-curable ink compositions containing polymerization initiators that are not candidates for being listed as Substances of Very High Concern (SVHCs) in Annex XIV of the REACH Regulation established by the European Union.

[0008] Examples of polymerization initiators that are not candidates for being listed as substances of very high concern in Annex XIV of the REACH Regulation established by the European Union include phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, and (2,4,6-trimethylbenzoyl)bis(p-tolyl)phosphine oxide.

[0009] However, using such polymerization initiators may result in the inability to meet the required properties for active energy ray-curable ink compositions compared to using polymerization initiators that have been candidates for inclusion as substances of very high concern.

[0010] The present invention aims to provide an ink composition that possesses the properties required for active energy ray curable ink compositions, even if it contains a polymerization initiator that is not a candidate for inclusion as a substance of very high concern under the REACH Regulation. [Means for solving the problem]

[0011] As a result of diligent research, the inventors of the present invention have found that the above-mentioned problems can be solved by including a polymerization initiator containing a polycyclic structure, along with a specific acylphosphine oxide-based polymerization initiator, and further including a polymerizable group-containing modified polysiloxane compound, thereby completing the present invention.

[0012] (1) An active energy ray-curable ink composition to be ejected by an inkjet method, comprising a polymerizable compound and a polymerization initiator, wherein the polymerization initiator comprises an acylphosphine oxide-based polymerization initiator A, and a polymerization initiator B different from the acylphosphine oxide-based polymerization initiator A and containing a polycyclic structure, the acylphosphine oxide-based polymerization initiator A contains at least one compound selected from the group consisting of the following general formula (1), the following general formula (2), and the following general formula (3), and the polymerizable compound contains a polymerizable group-containing modified polysiloxane compound, an ink composition.

Chemical Formula

Chemical Formula

Chemical Formula

[0013] (2) The ink composition according to (1), wherein the polymerizable compound further contains at least one selected from the group consisting of an N-vinyl group-containing polymerizable compound, a vinyl ether group-containing polymerizable compound, and a cyclic structure-containing polymerizable compound. The ink composition according to (1).

[0014] (3) The ink composition according to claim 1 or 2, wherein the polymerization initiator B containing a polycyclic structure is represented by the following general formula (4). The ink composition according to claim 1 or 2.

Chemical Formula

[0015] (4) An ink set comprising the ink composition described in any of (1) to (3).

[0016] (5) A printed material on which any of the ink compositions described in (1) to (3) is printed on the surface of a substrate.

[0017] (6) An inkjet recording device having a storage mechanism filled with any of the ink compositions described in (1) to (3).

[0018] (7) Dispense the ink composition described in any of (1) to (3) by an inkjet method. Recording method.

[0019] (8) A printed material is manufactured by ejecting an ink composition described in any of (1) to (3) by an inkjet method. A method for manufacturing printed materials. [Effects of the Invention]

[0020] According to the present invention, even if the polymerization initiator is not a candidate for inclusion as a substance of very high concern under the REACH Regulation, it still possesses the properties required for an active energy ray curable ink composition. [Modes for carrying out the invention]

[0021] The following describes specific embodiments of the present invention in detail, but the present invention is not limited in any way to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0022] ≪1. Active Energy Ray Curable Ink Composition≫ The active energy ray curable ink composition according to this embodiment contains a polymerizable compound and a polymerization initiator.

[0023] The polymerization initiator comprises at least one acylphosphine oxide polymerization initiator A selected from the group consisting of a compound represented by formula (1), a compound represented by formula (2), and a compound represented by formula (3), and polymerization initiator B, which differs from acylphosphine oxide polymerization initiator A in that it contains a polycyclic structure.

[0024] [ka]

[0025] [ka] In formula (2), R1 is a branched alkyl group having 1 to 10 carbon atoms.

[0026] [ka] In formula (3), R2 is a branched alkyl group having 1 to 10 carbon atoms, and R3 is a branched alkyl group having 1 to 10 carbon atoms.

[0027] By including a specific acylphosphine oxide polymerization initiator A along with a polymerization initiator B containing a polycyclic structure, it becomes possible to effectively suppress the decrease in curability of the ink composition, even when the polymerization initiator is not a substance of very high concern as listed in Annex XIV of the REACH Regulation.

[0028] Furthermore, the active energy ray curable ink composition according to this embodiment is characterized by containing a polymerizable group-containing modified polysiloxane compound as a polymerizable compound. By including such a polymerizable group-containing modified polysiloxane compound, the polymerization reaction can proceed further even without containing polymerization initiators, which are substances of very high concern as described in Annex XIV of the REACH Regulation, and as a result, it becomes possible to form a cured film that adheres to various substrates.

[0029] The active energy ray curing ink composition according to this embodiment may also be a colored ink containing a colorant. In this specification, "colorant" includes dyes and pigments, and is used as a concept that includes, for example, dyes or pigments contained in colored inks that form images such as yellow, magenta, cyan, black, red, orange, violet, blue, green, and intermediate or light colors thereof, as well as white dyes or white pigments contained in white inks and luminous colorants contained in metallic inks.

[0030] This colored ink may be a colored ink that forms an image in colors such as yellow, magenta, cyan, black, red, orange, violet, blue, green, and intermediate or light shades thereof. Alternatively, the colored ink may be a white ink containing a white pigment, or a metallic ink containing a luminous pigment, etc.

[0031] Furthermore, if the active energy ray-curable ink composition according to this embodiment contains a colorant, it may also contain a dispersant that disperses at least a portion of the colorant within the ink composition.

[0032] Furthermore, the active energy ray curable ink composition according to this embodiment may be a clear ink that does not contain a colorant. Specifically, it may be a primer ink for forming a primer layer on the surface of a substrate, an overcoat ink for forming an overcoat layer on the surface of a recording, a matte ink composition for removing the gloss of a recording (substrate), an ink composition for imparting gloss or texture, or an ink containing an ultraviolet absorber or light stabilizer for forming a weather-resistant layer.

[0033] In addition, the water content in the active energy ray curable ink composition according to this embodiment is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 1.0% by mass or less, and even more preferably 0.5% by mass or less of the total amount of ink composition.

[0034] The following describes each component included in the active energy ray curable ink composition according to this embodiment.

[0035] [Polymerizable compound] The active energy ray curable ink composition according to this embodiment contains a polymerizable compound. A polymerizable compound is a compound (polymerizable monomer) that has one or more ethylenically unsaturated double bonds and polymerizes to form a cured product when irradiated with active energy rays. Active energy rays include electromagnetic waves such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, visible light, infrared rays, X-rays, and gamma rays, as well as electron beams, proton beams, and neutron beams. This polymerizable compound is mainly in liquid form and has the function of polymerizing to form a cured product, as well as the function of a dispersion medium or solvent for the ink composition.

[0036] The polymerizable compound may be a monofunctional polymerizable compound having one ethylenically unsaturated double bond, or a polyfunctional polymerizable compound having two or more ethylenically unsaturated double bonds.

[0037] Furthermore, the polymerizable compound may be a polymerizable compound with a relatively large weight-average molecular weight, such as an oligomer.

[0038] The polymerizable compound contained in the active energy ray curable ink composition according to this embodiment contains a polymerizable group-containing modified polysiloxane compound. A polymerizable group-containing modified polysiloxane compound is a polymerizable compound that has an ethylenically unsaturated double bond and a polysiloxane structure.

[0039] As polymerizable compounds having a polysiloxane structure, for example, compounds represented by the following formula (5) can be used.

[0040] [ka] In formula (5), R a , R b R is a hydrogen or methyl group, c、 R d X is an alkyl group, aralkyl group, polyester group, or polyether group, and X is a polymerizable functional group.

[0041] By including a polymerizable group-containing modified polysiloxane compound, it is possible to suppress bleeding (smearing) on ​​the surface of the formed cured film and to smooth the surface of the cured film, thereby improving the gloss of the cured film surface. Furthermore, by including a polymerizable group-containing modified polysiloxane compound, good compatibility with polymerizable compounds in the ink composition can be maintained, and the fluidity of the ink inside the inkjet head and inkjet printer can be improved, thereby improving inkjet ejection performance. Moreover, even if polymerization initiators, which are substances of very high concern listed in Annex XIV of the REACH Regulation, are not included, the decrease in curability of the ink composition can be suppressed, and the coating film can be cured uniformly, resulting in the formation of a cured film that adheres to various substrates, and the gloss and abrasion resistance of the cured coating film can be improved. A polymerizable functional group is a functional group having one or more ethylenically unsaturated double bonds. Vinyl groups, acrylic groups, and methacrylate groups are preferred as polymerizable functional groups.

[0042] Examples of polymerizable group-containing modified polysiloxane compounds include BYKUV3570, BYKUV3500, BYK-UV3505, and BYKUV3510 from BIC Chemie Japan, and TEGO RAD 2010 and TEGO RAD 2300 from Evonik Degussa Japan.

[0043] The content of the polymerizable group-containing modified polysiloxane compound is not particularly limited, but it is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, in the total amount of the ink composition. The content of the polymerizable group-containing modified polysiloxane compound is not particularly limited, but it is preferably 10.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 5.0% by mass or less, in the total amount of the ink composition. The content of the polymerizable group-containing modified polysiloxane compound is not particularly limited, but in order to obtain the effects of the polymerizable group-containing modified polysiloxane compound and maintain good curability of the ink composition and physical properties of the cured coating film, it is preferably 0.1% by mass or more and 10.0% by mass or less, more preferably 0.3% by mass or more and 7.0% by mass or less, and even more preferably 0.5% by mass or more and 5.0% by mass or less, in the total amount of the ink composition.

[0044] Furthermore, the active energy ray curable ink composition according to this embodiment may contain other polymerizable compounds in addition to the polymerizable group-containing modified polysiloxane compound. Examples of other polymerizable compounds include N-vinyl group-containing polymerizable compounds, vinyl ether group-containing polymerizable compounds, and cyclic structure-containing polymerizable compounds. By including these polymerizable compounds, it is possible to improve the physical properties of the ink composition and the cured coating film, such as substrate adhesion, curability, and abrasion resistance.

[0045] N-vinyl group-containing polymerizable compounds are polymerizable compounds that have an N-vinyl group (C=CN-) in their structural formula, vinyl ether group-containing polymerizable compounds are polymerizable compounds that have a vinyl ether group (C=CO-) in their structural formula, and cyclic structure-containing polymerizable compounds are polymerizable compounds that have a cyclic structure such as an aromatic ring, aliphatic ring, or heterocycle in their structural formula.

[0046] Among these, it is preferable that the polymerizable compound contains a cyclic structure. Examples of polymerizable compounds containing a cyclic structure include polymerizable compounds containing oxygen-containing heterocyclic rings, polymerizable compounds containing nitrogen-containing heterocyclic rings, polymerizable compounds containing aromatic rings, and polymerizable compounds containing alicyclic structures.

[0047] Examples of oxygen-containing heterocyclic polymerizable compounds include cyclic trimethylolpropane formal acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)arylate, tetrahydrofurfuryl (meth)acrylate, alkoxylated tetrahydrofurfuryl (meth)acrylate, (2-methyl-2-isobutyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (cyclohexanespiro-2-(1,3-dioxolan-4-yl))methyl (meth)acrylate, γ-butyrolactone (meth)acrylate, glycerin carbonate (meth)acrylate, and 2-isopropenyl-2-oxazoline. These may also be modified in various ways, such as alkoxy modification and caprolactone modification. The oxygen-containing heterocyclic polymerizable compound may be a polyfunctional polymerizable compound having two or more ethylenically unsaturated double bonds, but it is preferable that it be a monofunctional polymerizable compound having one ethylenically unsaturated double bond.

[0048] Examples of nitrogen-containing heterocyclic polymerizable compounds include N-vinylcaprolactam, 4-acryloylmorpholine, 5-methyl-3-vinyloxazolidine-2-one, N-vinylpyrrole acrylate, imido(meth)acrylate, N-vinylpyrrolidone, N-vinyloxazolidone, 5-methyl-3-vinyl-2-oxazolidinone, 2-vinyl-2-oxazoline, N-vinylpyridine, N-vinylimidazole, 2-isopropenyl-2-oxazoline, and N-vinylsuccinimide. These may also be modified in various ways, such as alkoxy modification and caprolactone modification. Nitrogen-containing heterocyclic polymerizable compounds may be polyfunctional polymerizable compounds having two or more ethylenically unsaturated double bonds, but it is preferable that they be monofunctional polymerizable compounds having one ethylenically unsaturated double bond.

[0049] Examples of polymerizable compounds containing aromatic rings include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, cresol (meth)acrylate, 2-acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxypropyl phthalate, paracumylphenoxyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, phenyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, and styrene. These may also have various modifications such as alkoxy modification and caprolactone modification. The aromatic ring-containing polymerizable compound may be a polyfunctional polymerizable compound having two or more ethylenically unsaturated double bonds, but it is preferable that it be a monofunctional polymerizable compound having one ethylenically unsaturated double bond.

[0050] Examples of polymerizable compounds containing alicyclic structures include isobornyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, n-butylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-acryloyloxyethylhexahydrophthalate, 1-adamantyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, hydroxycyclohexyl (meth)acrylate, 3-3-5-trimethylcyclohexyl (meth)acrylate, vinylcyclohexane, tert-butyl-4-ethynylcyclohexane, cycloheptyl (meth)acrylate, cyclopentyl (meth)acrylate, and cyclobutyl (meth)acrylate. These may also have various modifications such as alkoxy modification and caprolactone modification. The polymerizable compound containing an alicyclic structure may be a polyfunctional polymerizable compound having two or more ethylenically unsaturated double bonds, but it is preferable that it be a monofunctional polymerizable compound having one ethylenically unsaturated double bond.

[0051] The content of the polymerizable compound containing a cyclic structure is not particularly limited, but is preferably 5.0% by mass or more, more preferably 7.0% by mass or more, and even more preferably 10.0% by mass or more, of the total amount of the ink composition. The content of the polymerizable compound containing a cyclic structure is preferably 90.0% by mass or less, more preferably 85.0% by mass or less, and even more preferably 80.0% by mass or less, of the total amount of the ink composition. The content of the polymerizable compound containing a cyclic structure is preferably 5.0% by mass or more and 90.0% by mass or less, more preferably 7.0% by mass or more and 85.0% by mass or less, and even more preferably 10.0% by mass or more and 80.0% by mass or less, of the total amount of the ink composition.

[0052] Furthermore, the active energy ray curable ink composition according to this embodiment may contain other polymerizable compounds in addition to polymerizable group-containing modified polysiloxane compounds and cyclic structure-containing polymerizable compounds.

[0053] Other polymerizable compounds include isooctyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, stearyl (meth)acrylate, isodecyl (meth)acrylate, caprolactone (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, 2-methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, and 2-ethyl Hexyl (meth)acrylate, methyl (meth)acrylate, butyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, octyl (meth)acrylate, trifluoroethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methyl α-(hydroxymethyl) (meth)acrylate Ethyl α-(hydroxymethyl)(meth)acrylate, n-butyl α-(hydroxymethyl)(meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-vinyl methyl carbamate, N,N-methylvinyl acetamide, (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acrylonitrile, N,N-diethyl (meth)acrylamide, N-ethyl-N-methyl-(meth)acrylamide, N,N-dipropyl (meth Examples include acrylamide, N,N-dibutyl(meth)acrylamide, N-ethyl-N-butyl-acrylamide, N-isopropyl(meth)acrylamide, N-propyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-octyl(meth)acrylamide, N-2-ethylhexyl(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-[3-(dimethylamino)propyl](meth)acrylamide, etc. These may also have various modifications such as alkoxy modification and caprolactone modification.

[0054] Furthermore, the active energy ray curable ink composition according to this embodiment may also contain a polyfunctional polymerizable compound having two or more ethylenically unsaturated double bonds. Examples of polyfunctional polymerizable compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, long-chain aliphatic di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,6-hexanedi Ethylene oxide modification (EO modification) of 1,6-hexanediol di(meth)acrylate (2), ethylene oxide modification (EO modification) of 1,6-hexanediol di(meth)acrylate (3), ethylene oxide modification (EO modification) of 1,6-hexanediol di(meth)acrylate (5), propylene oxide modification (PO modification) of 1,6-hexanediol di(meth)acrylate (2), propylene oxide modification (PO modification) of 1,6-hexanediol di(meth)acrylate (3), 1,9-nonanediol di(meth) ) Acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide modified (EO modified) neopentyl glycol di(meth)acrylate (2), ethylene oxide modified (EO modified) neopentyl glycol di(meth)acrylate (3), propylene oxide modified (PO modified) neopentyl glycol di(meth)acrylate (2), propion oxide modified (PO modified) neopentyl glycol di(meth)acrylate (8) , propylene oxide modified (PO modified) neopentyl glycol di(meth)acrylate (16), hydroxypivalate neopentyl glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate caprolactone modified (2), hydroxypivalate neopentyl glycol di(meth)acrylate caprolactone modified (4), polyalkylene glycol diacrylate, polyalkylene glycol diacrylate ethylene oxide modified (EO modified) (4),Polyalkylene glycol diacrylate modified with ethylene oxide (EO) (9), polyalkylene glycol diacrylate modified with ethylene oxide (EO) (14), polyalkylene glycol diacrylate modified with ethylene oxide (EO) (23), polyalkylene glycol diacrylate modified with ethylene oxide (EO) (46), polyalkylene glycol diacrylate modified with propylene oxide (PO) (3), polyalkylene glycol diacrylate modified with propylene oxide (PO) )(7), propylene oxide modification of polyalkylene glycol diacrylate (PO modification)(12), ethylene oxide and propylene oxide modification of polyalkylene glycol diacrylate (PO modification (12) & EO modification (6)), ethylene oxide and propylene oxide modification of polyalkylene glycol diacrylate (PO modification (6) & EO modification (12)), ethylene oxide and propylene oxide modification of polyalkylene glycol diacrylate (PO modification (4) & EO modification (12)), polyalkylene glycol di Modification of acrylates with ethylene oxide and propylene oxide (PO modification (4) & EO modification (17)), modification of polyalkylene glycol diacrylates with ethylene oxide and propylene oxide (PO modification (13) & EO modification (5)), modification of polyalkylene glycol diacrylates with butylene oxide (BO modification) (3.5), modification of polyalkylene glycol diacrylates with butylene oxide (BO modification) (9), modification of polyalkylene glycol diacrylates with butylene oxide (BO modification) (14), stearic acid modified pen Taerythritol di(meth)acrylate, propylene glycol di(meth)acrylate, glycerol di(meth)acrylate, triethylene glycol di(meth)acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, tetraethylene glycol di(meth)acrylate, tetramethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene di(meth)acrylate,Triglycerol di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, methoxylated cyclohexyl di(meth)acrylate, acrylic isocyanurate, bis(acryloxyneopentyl glycol) adipate, bisphenol A di(meth)acrylate, ethylene oxide-modified (EO-modified) bisphenol A di(meth)acrylate (2), ethylene oxide-modified (EO-modified) bisphenol A di(meth)acrylate Modified (3), ethylene oxide modification (EO modification) of bisphenol A di(meth)acrylate (4), ethylene oxide modification (EO modification) of bisphenol A di(meth)acrylate (10), ethylene oxide modification (EO modification) of bisphenol A di(meth)acrylate (20), ethylene oxide modification (EO modification) of bisphenol A di(meth)acrylate (30), propylene oxide modification (PO modification) of bisphenol A di(meth)acrylate (3), ethylene oxide modification of bisphenol A di(meth)acrylate Modified bisphenol and propylene oxide (PO modification (6) & EO modification (3)), tetrabromobisphenol A di(meth)acrylate, bisphenol S di(meth)acrylate, butanediol di(meth)acrylate, phthalate di(meth)acrylate, phosphate di(meth)acrylate, zinc di(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethylene oxide modification (EO modification) of pentaerythritol tetra(meth)acrylate (4), pentaerythritol tetra(meth)acrylate Ethylene oxide modification (EO modification) of (35), propylene oxide modification (PO modification) of pentaerythritol tetra(meth)acrylate (4), propylene oxide modification (PO modification) of pentaerythritol tetra(meth)acrylate (10), ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide modification (EO modification) of dipentaerythritol hexa(meth)acrylate (6),Dipentaerythritol hexa(meth)acrylate modified with ethylene oxide (EO) (12), dipentaerythritol hexa(meth)acrylate modified with ethylene oxide (EO) (18), dipentaerythritol hexa(meth)acrylate modified with ethylene oxide (EO) (24), dipentaerythritol hexa(meth)acrylate modified with ethylene oxide (EO) (48), dipentaerythritol hexa(meth)acrylate modified with propylene oxide (PO) (6), dipentaerythritol Caprolactone-modified trimethylolpropane(meth)acrylate (2), caprolactone-modified dipentaerythritol hexa(meth)acrylate (3), caprolactone-modified dipentaerythritol hexa(meth)acrylate (6), caprolactone-modified dipentaerythritol hexa(meth)acrylate (12), trimethylolpropane(meth)acrylate, ethylene oxide-modified (EO-modified) trimethylolpropane(meth)acrylate (3), ethylene oxide-modified trimethylolpropane(meth)acrylate Side modification (EO modification) (6), ethylene oxide modification (EO modification) of trimethylolpropane tri(meth)acrylate (9), ethylene oxide modification (EO modification) of trimethylolpropane tri(meth)acrylate (15), ethylene oxide modification (EO modification) of trimethylolpropane tri(meth)acrylate (20), ethylene oxide modification (EO modification) of trimethylolpropane tri(meth)acrylate (30), propylene oxide modification (PO modification) of trimethylolpropane tri(meth)acrylate (3), Propylene oxide modification (PO modification) of trimethylolpropane tri(meth)acrylate (6), pentaerythritol tri(meth)acrylate, glycerin tri(meth)acrylate, ethylene oxide modification (EO modification) of glycerin tri(meth)acrylate (3), ethylene oxide modification (EO modification) of glycerin tri(meth)acrylate (6), ethylene oxide modification (EO modification) of glycerin tri(meth)acrylate (9), ethylene oxide modification (EO modification) of glycerin tri(meth)acrylate (20),Examples include glycerin tri(meth)acrylate modified with propylene oxide (PO modification) (3), glycerin tri(meth)acrylate modified with propylene oxide (PO modification) (5.5), glycerin tri(meth)acrylate modified with propylene oxide (PO modification) (6), glycerin tri(meth)acrylate modified with propylene oxide (PO modification) (9), dimethylol tricyclodecanediaacrylate, and (meth)acrylates with different modification levels, modification species, and structural differences.

[0055] The content of polyfunctional polymerizable compounds having two or more ethylenically unsaturated double bonds is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more of the total ink composition. The content of polyfunctional polymerizable compounds having two or more ethylenically unsaturated double bonds is preferably 80% by mass or less, more preferably 78% by mass or less, and even more preferably 75% by mass or less of the total ink composition. The content of polyfunctional polymerizable compounds having two or more ethylenically unsaturated double bonds is preferably 5% by mass or more and 80% by mass or less, more preferably 10% by mass or more and 78% by mass or less, and even more preferably 15% by mass or more and 75% by mass or less of the total ink composition. By being within this range, good curability and strength of the cured coating film can be achieved.

[0056] Furthermore, the active energy ray curable ink composition according to this embodiment may also contain a polymerizable oligomer in addition to the polymerizable compound described above. A polymerizable oligomer generally refers to a polymer in which a relatively small number of monomers are bonded together. An example of a polymerizable oligomer is a compound in which several to tens of constituent unit molecules are polymerized and which has a weight-average molecular weight of less than 10,000. By including a predetermined amount of polymerizable oligomer, it is possible to adjust the curability and viscosity of the ink composition.

[0057] Examples of polymerizable oligomers include urethane acrylate oligomers, epoxy acrylate oligomers, polyester acrylate oligomers, polymer-type acrylate (acrylic acrylate) oligomers, amine-modified acrylate oligomers, acid-modified acrylate oligomers, and various other types, which can be obtained from companies such as Rahn AG, Sartomer, Daicel Corporation, Taisei Fine Chemicals, Mitsubishi Chemical Corporation, Daiichi Kogyo Seiyaku Co., Ltd., Kyoeisha Chemical Co., Ltd., Shin Nakamura Chemical Co., Ltd., and others.

[0058] If polymerizable oligomers are included, the polymerizable oligomer content is preferably 1.0% by mass or more, more preferably 1.3% by mass or more, and even more preferably 1.5% by mass or more, based on the total amount of the ink composition. The polymerizable oligomer content is preferably 20.0% by mass or less, more preferably 17.0% by mass or less, and even more preferably 15.0% by mass or less, based on the total amount of the ink composition. The polymerizable oligomer content is preferably 1.0% by mass or more and 20.0% by mass or less, more preferably 1.3% by mass or more and 17.0% by mass or less, and even more preferably 1.5% by mass or more and 15.0% by mass or less, based on the total amount of the ink composition.

[0059] These polymerizable compounds may be solid or liquid at room temperature. Among these, it is preferable that at least one of the polymerizable compounds contained in the ink composition according to this embodiment is liquid at room temperature. Because the polymerizable compound is liquid at room temperature, this liquid polymerizable compound can act as a solvent (dispersion medium) for dissolving or dispersing each component contained in the ink composition.

[0060] The content of polymerizable compounds is not particularly limited, but is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more of the total ink composition. A polymerizable compound content of 40% by mass or more of the total ink composition improves the curability of the cured film formed when irradiated with active energy rays. The polymerizable compound content is preferably 90% by mass or less of the total ink composition, more preferably 87% by mass or less, and even more preferably 85% by mass or less. A polymerizable compound content of 90% by mass or less of the total ink composition allows for a relative increase in the content of colorants, etc., thereby imparting desired properties to the ink composition and the resulting printed material. The polymerizable compound content is preferably 40% by mass or more and 90% by mass or less of the total ink composition, more preferably 50% by mass or more and 87% by mass or less, and even more preferably 60% by mass or more and 85% by mass or less.

[0061] [Polymerization initiator] The active energy ray curable ink composition according to this embodiment contains an acylphosphine oxide-based polymerization initiator A and a polymerization initiator B that differs from acylphosphine oxide-based polymerization initiator A and contains a polycyclic structure.

[0062] Acylphosphine oxide polymerization initiator A contains at least one compound selected from the group consisting of the following general formulas (1), (2), and (3).

[0063] [ka]

[0064] [ka] In formula (2), R1 is a branched alkyl group having 1 to 10 carbon atoms.

[0065] [ka] In formula (3), R2 is a branched alkyl group having 1 to 10 carbon atoms, and R3 is a branched alkyl group having 1 to 10 carbon atoms.

[0066] A general formula (1) is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0067] A preferred example of general formula (2) is ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate. Other compounds can be used in which R1 is a branched alkyl group having 1 to 10 carbon atoms, such as a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, or hexyl group. These compounds are selected from those that do not fall under the category of substances of very high concern as described in Annex XIV of the REACH Regulation.

[0068] A preferred example of general formula (3) is (2,4,6-trimethylbenzoyl)bis(p-tolyl)phosphine oxide. In addition, compounds in which R2 and R3 are independently branched alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, and hexyl groups, can be used. These compounds are selected from those that do not fall under the category of substances of very high concern as described in Annex XIV of the REACH Regulation.

[0069] These acylphosphine oxide polymerization initiators A do not fall under the category of substances of very high concern as listed in Annex XIV of the REACH Regulation.

[0070] The content of acylphosphine oxide polymerization initiator A is not particularly limited, but is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2.0% by mass or more, in the total amount of the ink composition. The content of acylphosphine oxide polymerization initiator is preferably 20.0% by mass or less, more preferably 17.0% by mass or less, even more preferably 15.0% by mass or less, and even more preferably 12.0% by mass or less, in the total amount of the ink composition.

[0071] Furthermore, the active energy ray curable ink composition according to this embodiment is characterized by containing a specific acylphosphine oxide-based polymerization initiator A, along with a polymerization initiator B containing a polycyclic structure. This makes it possible to effectively suppress a decrease in the curability of the ink composition even when it does not contain polymerization initiators that are substances of very high concern as described in Annex XIV of the REACH Regulation.

[0072] Polymerization initiator B containing a polycyclic structure can be a polymerization initiator containing two or more structures selected from condensed polycyclic structures, aromatic rings, alicyclic structures, heterocyclic structures, and aromatic heterocyclic structures. Examples include polymerization initiators having a condensed polycyclic structure and a morpholine structure, polymerization initiators containing a condensed polycyclic structure and an aromatic ring, benzophenone-based polymerization initiators containing multiple aromatic rings, and aromatic ketone-based polymerization initiators containing thioxanthones, etc. Among these, polymerization initiators having a condensed polycyclic structure and a morpholine structure are preferred. Examples of polymerization initiator B containing a polycyclic structure include 4-(4-methylphenylthio)benzophenone, 1,1'-(methylene-di-4,1-phenylene)bis(2-hydroxy-2-methyl-1-propanone), 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-"4-(hydrochyethoxy)-phenyl"-2-hydroxy-2-methyl-propan-1-one, 4,4'-bis(diethylamino)benzophenone, 1,4-diethoxynaphthalene, 2,4-diethylthioxanthene-9-one, 2-isopropyl-9H-thioxanthone-9, isopropyl-9H-thioxanthene-9-one, etc., but are not limited to these and may be included as long as they are not substances of very high concern as listed in Annex XIV of the REACH Regulation.

[0073] As a polymerization initiator having a condensed polycyclic structure and a morpholine structure, it is preferable to use a compound of the following general formula (4).

[0074] [ka] (In formula (4), R4 is a branched alkyl group having 1 to 10 carbon atoms, and R5 (This is a branched alkyl group having 1 to 10 carbon atoms.)

[0075] A preferred example of a compound of such general formula (4) is 1-(9,9-dibutyl-9H-fluoren-2-yl)-2-methyl-2-morpholine-4-ylpropan-1-one. In addition, compounds in which R4 and R5 are each independently a branched alkyl group having 1 to 10 carbon atoms, such as a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, or hexyl group, can be used. These compounds are selected from those that do not fall under the category of substances of very high concern as described in Annex XIV of the REACH Regulation.

[0076] The content of polymerization initiator B containing a polycyclic structure is not particularly limited, but is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more, in the total amount of the ink composition. The content of polymerization initiator B containing a polycyclic structure is preferably 12.0% by mass or less, more preferably 10.0% by mass or less, and even more preferably 8.0% by mass or less, in the total amount of the ink composition. The content of polymerization initiator B containing a polycyclic structure is preferably 0.5% by mass or more and 12.0% by mass or less, more preferably 0.8% by mass or more and 10.0% by mass or less, and even more preferably 1.0% by mass or more and even more preferably 8.0% by mass or less, in the total amount of the ink composition. By being within this range, the curability of the ink composition can be improved.

[0077] Furthermore, the ratio (Wb / Wa) of the content of a specific acylphosphine oxide polymerization initiator A to the content of a polymerization initiator B containing a polycyclic structure (Wb) is preferably 0.05 or higher, more preferably 0.10 or higher, even more preferably 0.13 or higher, and still more preferably 0.15 or higher. The ratio (Wb / Wa) of the content of a specific acylphosphine oxide polymerization initiator A to the content of a polymerization initiator B containing a polycyclic structure (Wb) is preferably 1.50 or lower, more preferably 1.40 or lower, even more preferably 1.30 or lower, and still more preferably 1.0 or lower. The ratio (Wb / Wa) of the content of a specific acylphosphine oxide polymerization initiator A to the content of a polycyclic polymerization initiator B (Wb) is preferably 0.05 to 1.50, more preferably 0.10 to 1.40, and even more preferably 0.13 to 1.30. By including different types of polymerization initiators within this range, the curability of the ink composition can be improved.

[0078] The ink composition according to this embodiment may further contain polymerization initiators other than those described above, provided that they do not fall under the category of substances of very high concern as described in Annex XIV of the EACH Regulation.

[0079] The content of the polymerization initiator in the active energy ray curable ink composition according to this embodiment is not particularly limited, but is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2.0% by mass or more of the total ink composition. The content of the polymerization initiator is preferably 15.0% by mass or less, more preferably 12.0% by mass or less, and even more preferably 10.0% by mass or less of the total ink composition. The content of the polymerization initiator is preferably 1.0% by mass or more and 15.0% by mass or less of the total ink composition, more preferably 1.5% by mass or more and 12.0% by mass or less, and even more preferably 2.0% by mass or more and 10.0% by mass or less of the total ink composition.

[0080] [Polymerization inhibitor] The ink composition according to this embodiment may optionally contain a polymerization inhibitor. The polymerization inhibitor is not particularly limited, and for example, diphenylpicryl hydrazide, tri-p-nitrophenylmethyl, p-benzoquinone, p-tert-butylcatechol, picric acid, copper chloride, methyl hydroquinone, methoquinone, tert-butylhydroquinone, phenothiazines, nitrosamines, and other polymerization inhibitors can be used.

[0081] [Colorants] The active energy ray-curable ink composition according to this embodiment may contain a colorant as needed. When the active energy ray-curable ink composition according to this embodiment contains a colorant, the colorant is not particularly limited and may be a dye-based or a pigment-based colorant, but it is preferable to use a pigment (pigment-based colorant) from the viewpoint of good resistance such as water resistance and light resistance of the recorded material. The pigments that can be used in the active energy ray-curable ink composition according to this embodiment are not particularly limited and include organic pigments or inorganic pigments used in conventional ink compositions. These may be used individually or in combination of two or more. The ink composition according to this embodiment does not have to contain a colorant. Alternatively, the pigment or dye may be incorporated into the resin and used.

[0082] In the active energy ray curable ink composition according to this embodiment, when a pigment is used, the dispersion stability of the pigment can be improved by using dispersants, dispersion aids (pigment derivatives), and surfactants described later.

[0083] Specific examples of organic pigments include, for instance, insoluble azo pigments, soluble azo pigments, derivatives from dyes, phthalocyanine organic pigments, quinacridone organic pigments, perylene organic pigments, perinone organic pigments, azomethine organic pigments, anthraquinone organic pigments (anthrone organic pigments), xanthene organic pigments, diketopyrrolopyrrole organic pigments, dioxazine organic pigments, nickel azo pigments, isoindolinone organic pigments, pyranthrone organic pigments, thioindigo organic pigments, condensed azo organic pigments, benzimidazolon organic pigments, quinophthalone organic pigments, isoindoline organic pigments, quinacridone solid solution pigments, perylene solid solution pigments and other organic solid solution pigments, as well as other pigments such as lake pigments and carbon black.

[0084] Examples of organic pigments using Color Index (CI) numbers include: CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 117, 120, 125, 128, 129, 130, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, 213, 214; CI Pigment Red 5, 7, 9, 12, 48, 49, 52, 53, 57:1, 97, 112, 122, 123, 146, 149, 150, 168, 177, 180, 184 Examples include 192, 202, 206, 208, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 269, 291, CI Pigment Orange 16, 36, 43, 51, 55, 59, 61, 64, 71, 73, CI Pigment Violet 19, 23, 29, 30, 37, 40, 50, CI Pigment Blue 15, 15:1, 15:3, 15:4, 15:6, 16, 22, 60, 64, CI Pigment Green 7, 36, 58, 59, 62, 63, CI Pigment Brown 23, 25, 26, CI Pigment Black 7, etc.

[0085] Specific examples of dyes that can be used in the active energy ray curable ink composition according to this embodiment include azo dyes, benzoquinone dyes, naphthoquinone dyes, anthraquinone dyes, cyanine dyes, squarylium dyes, croconium dyes, merocyanine dyes, stilbene dyes, diarylmethane dyes, triarylmethane dyes, fluorane dyes, spiropyran dyes, phthalocyanine dyes, indigo dyes such as indigoids, fulgide dyes, nickel complex dyes, and azulene dyes.

[0086] In the active energy ray curable ink composition according to this embodiment, specific examples of inorganic pigments that can be used include titanium dioxide, barium sulfate, calcium carbonate, zinc oxide, barium carbonate, silica, talc, clay, synthetic mica, alumina, zinc oxide, lead sulfate, lead yellow, zinc yellow, red iron(III) oxide, ultramarine, Prussian blue, chromium oxide green, cobalt green, amber, titanium black, aluminum, titanium, indium, nickel, chromium, gold, silver, copper, synthetic iron black, iron oxide, mica, fish scale foil, bismuth acid chloride, inorganic solid solution pigments, and the like. In addition to the above pigments, other materials with optical properties or functionalities other than decorative purposes, such as conductive pigments, insulating pigments, pigments that absorb specific wavelengths, and pigments that emit or reflect specific wavelengths, can also be used.

[0087] In the active energy ray curable ink composition according to this embodiment, the average particle size of the pigment that can be contained is not particularly limited, as long as it enables the desired color development. Although it varies depending on the type of pigment used, from the viewpoint of good dispersibility and dispersion stability of the pigment and obtaining sufficient coloring power, the average particle size is preferably in the range of 5 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. The lightfastness of the ink composition can be improved by having the average particle size above the above lower limit. From the viewpoint of dispersion stability in the ink composition and inkjet ejection performance, the average particle size is preferably in the range of 1000 nm or less, more preferably 800 nm or less, even more preferably 500 nm or less, and even more preferably 350 nm. The average particle size of the pigment is preferably in the range of 5 nm or more and 1000 nm or less, more preferably 20 nm or more and 800 nm or less, and even more preferably 30 nm or more and 500 nm or less.

[0088] In this embodiment, the volume-average particle diameter of the pigment is the volume-based cumulative 50% particle diameter (D50) measured under 25°C conditions using a particle size distribution analyzer (such as the NANOTRACWAVE particle size analyzer manufactured by Microtrac Bell Co., Ltd., the "FPIA-3000S" manufactured by Sysmex Corporation, or the "FPAR-1000" manufactured by Otsuka Electronics Co., Ltd.). In this specification, "volume-based cumulative 50% particle diameter (D50)" refers to the particle diameter at which the cumulative volume calculated from the smallest diameter side becomes 50%. "Volume-based cumulative 50% particle diameter (D50)" may also be referred to as "volume-average particle diameter," "average particle diameter," or "median diameter."

[0089] In the active energy ray curable ink composition according to this embodiment, the pigment content is not particularly limited as long as it is possible to form the desired image, and can be adjusted as appropriate. Specifically, although it varies depending on the type of pigment, it is preferably in the range of 0.05% by mass or more, more preferably in the range of 0.08% by mass or more, and even more preferably in the range of 0.1% by mass or more, in the range of 0.1% by mass or more, in the range of 20% by mass or less, more preferably in the range of 15% by mass or less, and even more preferably in the range of 10% by mass or less, in the range of 0.05% by mass or more and 20% by mass or less, in the range of 0.08% by mass or more and 15% by mass or less, and even more preferably in the range of 0.1% by mass or more and 10% by mass or less, in the range of 0.05% by mass or more and 20% by mass or less, in the range of 20% by mass or less, which allows for an excellent balance between the dispersion stability of the pigment and the coloring power.

[0090] Furthermore, the active energy ray-curable ink composition according to this embodiment is not particularly limited in the colors to be recorded (printed), and may be selected and combined according to the purpose. The colors can be various inks such as yellow, magenta, cyan, black, red, orange, violet, blue, and green, as well as light magenta, light cyan, light black, white, clear, and glossy inks. In this case, the same type of colorant may be selected for the ink set containing the active energy ray-curable ink composition according to this embodiment.

[0091] [Dispersant] In the active energy ray curable ink composition according to this embodiment, a dispersant may be used as needed. Any dispersant used in ink compositions can be used as the dispersant. A polymeric dispersant is preferable as the dispersant. Such dispersants have a main chain made of polyester, polyacrylic, polyurethane, polyamine, polycaprolactone, etc., and side chains that have polar groups such as amino groups, carboxyl groups, sulfone groups, and hydroxyl groups. Examples of polyacrylic dispersants include Disperbyk-2000, 2001, 2008, 2009, 2010, 2020, 2020N, ​​2022, 2025, 2050, 2070, 2095, 2150, 2151, 2155, 2163, 2164, BYKJET-9130, 9131, 9132, 9133, 9151, 9152 (manufactured by BYK), EfkaPX4310, PX4320, PX4330, PA4401, 4402, PA4403, 4570, 7411, 7477, PX4700, PX4701, PX4703 (manufactured by BASF), and TREPLUS. Products such as D-1200, D-1410, D-1420, MD-1000 (manufactured by Otsuka Chemical Co., Ltd.), Floren DOPA-15BHFS, 17HF, 22, G-700, 900, NC-500, and GW-1500 (manufactured by Kyoeisha Chemical Co., Ltd.) are used. Examples of polycaprolactone-based dispersants include Ajisper PB821, PB822, PB881 (manufactured by Ajinomoto Fine Techno Co., Ltd.), Hinoact KF-1000, T-6000, T-7000, T-8000, T-8000E, T-9050 (manufactured by Kawaken Fine Chemical Co., Ltd.), Solsperse 20000, 24000, 32000, 32500, 32550, 32600, 33000, 33500, 34000, 35200, 36000, 37500, 39000, 71000, 76400, 76500, 86000, 88000, J180, J200 (manufactured by Lubrizol), and TEGO. Dispers 652, 655, 685, 688, and 690 (manufactured by Evonik) are used.Preferred dispersants include PB881, BYKJET-9130, 9131, 9132, 9133, 9151, 9152, EfkaPX4310, PX4320, PX4330, PX4700, PX4701, PX4703, Solsperse20000, 24000, 32000, 33000, 33500, 34000, 35200, 39000, 71000, 76500, 86000, 88000, J180, J200, TEGO Dispers655, 685, 688, 690, etc. These can be used individually or in mixtures thereof.

[0092] The content of the dispersant is not particularly limited, but it is preferable to adjust it according to the content of the colorant contained in the ink composition. When the colorant is an organic colorant, the upper limit of the dispersant content is preferably 80 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 35 parts by mass or less, per 100 parts by mass of the colorant.

[0093] When the colorant is an inorganic colorant, the upper limit of the dispersant content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the colorant.

[0094] [Dispersing agent] The active energy ray curable ink composition according to this embodiment may optionally contain a dispersion aid. The dispersion aid is adsorbed onto the surface of the colorant (pigment), and its functional groups enhance its affinity for polymerizable compounds and dispersants in the ink composition, thereby improving dispersion stability. As the dispersion aid, known pigment derivatives having functional groups such as acidic groups, basic groups, and neutral groups in the organic pigment residues can be used.

[0095] [Surfactants] The ink composition according to this embodiment may optionally contain a surfactant. The surfactant is not particularly limited.

[0096] The surfactant content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, based on the total amount of the ink composition. Furthermore, the surfactant content is preferably 5.0% by mass or less, more preferably 4.5% by mass or less, and even more preferably 4.0% by mass or less, based on the total amount of the ink composition. By setting the surfactant content to 0.1% by mass or more, or 5.0% by mass or less, the ink composition will have desirable wettability with respect to thermoplastic resin substrates, etc., and when recording (forming an image) on the substrate, the active energy ray curable ink composition will be able to wet and spread without causing repulsion, making it a particularly preferable ink composition. The surfactant content is preferably 0.1% by mass or more and 5.0% by mass or less, more preferably 0.2% by mass or more and 4.5% by mass or less, and even more preferably 0.3% by mass or more and 4.0% by mass or less, based on the total amount of the ink composition.

[0097] [Binder resin] The active energy ray curable ink composition according to this embodiment may optionally contain a binder resin. The term "binder resin" here refers to a non-polymerizable resin, distinct from polymerizable resins, polymerizable oligomers, surfactants, dispersants for dispersing colorants, and other additives. The resin is not particularly limited, but examples include acrylic resins, polystyrene resins, polyester resins, polyethylene terephthalate resins, vinyl chloride resins, vinyl acetate resins, vinyl chloride vinyl acetate copolymer resins, polyethylene resins, polyurethane resins, rosin-modified resins, phenolic resins, xylene resins, terpene resins, polyamide resins, vinyltoluene-α-methylstyrene copolymers, ethylene-vinyl acetate copolymers, cellulose resins, silicone resins, acrylamide resins, epoxy resins, diallyl phthalate resins, allyl resins, or copolymers or mixtures thereof. Among these, it is preferable that the ink composition contains one or more of the following: vinyl chloride-vinyl acetate copolymer resin, polyethylene terephthalate resin, diallyl phthalate resin, acrylic resin, allyl resin, xylene resin, and cellulose resin. It is even more preferable that the binder resin contains at least one selected from the group consisting of vinyl chloride-vinyl acetate copolymer resin, diallyl phthalate resin, xylene resin, and acrylic resin. The weight-average molecular weight of the binder resin is preferably 10,000 or more, and more preferably 15,000 or more. The weight-average molecular weight of the binder resin is preferably 500,000 or less, and more preferably 300,000 or less. Having the weight-average molecular weight of the binder resin within this range allows for good storage stability, discharge properties, and physical properties of the cured coating film of the ink composition.

[0098] When the active energy ray curable ink composition according to this embodiment contains a binder resin, the binder resin content is not particularly limited, but is preferably 0.05% by mass or more of the total ink composition, more preferably 0.08% by mass or more, even more preferably 0.1% by mass or more, and still more preferably 0.3% by mass or more. The binder resin content is preferably 20.0% by mass or less of the total ink composition, more preferably 15.0% by mass or less, even more preferably 10.0% by mass or less, and still more preferably 5.0% by mass or less. The binder resin content is preferably 0.05% by mass or more and 20.0% by mass or less of the total ink composition, more preferably 0.08% by mass or more and 15.0% by mass or less, and still more preferably 0.1% by mass or more and 10.0% by mass or less.

[0099] [Other additives] The ink composition according to this embodiment may also contain various additives such as organic solvents, plasticizers, light stabilizers, waxes, ultraviolet absorbers, antioxidants, orientation agents, antibacterial agents, and antiviral agents.

[0100] Furthermore, the ink composition according to this embodiment may contain a volatile organic solvent, but if the polymerizable compound contained is liquid at room temperature, the polymerizable compound acts as a solvent (dispersion medium) that dissolves or disperses each component, so it is not necessary to contain a volatile organic solvent. In particular, if the polymerizable compound contained is liquid at room temperature, the content of the volatile organic solvent is preferably 20.0% by mass or less, more preferably 10.0% by mass or less, even more preferably 5.0% by mass or less, and still more preferably 1.0% by mass or less of the total amount of the ink composition. By containing a polymerizable compound that is liquid at room temperature and having a volatile organic solvent content of 20.0% by mass or less of the total amount of the ink composition, it is possible to suppress the precipitation of components due to the volatilization of the ink composition in the inkjet nozzle, thereby further improving the inkjet ejection performance.

[0101] (Viscosity and surface tension of the ink composition) The viscosity of the ink composition according to this embodiment is preferably 30 mPa·s or less, more preferably 25 mPa·s or less, and even more preferably 22 mPa·s or less at the ejection temperature (e.g., 40°C) from the viewpoint of inkjet ejection performance and ejection stability. Furthermore, the viscosity of the ink composition according to this embodiment is preferably 3 mPa·s or more, more preferably 5 mPa·s or more, and even more preferably 8 mPa·s or more at the ejection temperature (e.g., 40°C), but it is preferable to adjust it appropriately according to the inkjet head used. Viscosity can be measured with a vibrating viscometer, rheometer, falling ball viscometer, etc.

[0102] Furthermore, the surface tension of the ink composition according to this embodiment is preferably 20 mN / m or more, more preferably 23 mN / m or more, and even more preferably 25 mN / m or more at 25°C, from the viewpoint of inkjet ejection performance, ejection stability, and leveling performance to the substrate. Furthermore, the surface tension of the ink composition according to this embodiment is preferably 40 mN / m or less, more preferably 37 mN / m or less, and even more preferably 35 mN / m or less.

[0103] (Method of manufacturing ink composition) The method for producing the active energy ray curable ink composition of one embodiment of the present invention is not particularly limited, and conventionally known methods can be used. For example, a polymerizable compound, a colorant, and a dispersant as needed are mixed and dispersed using a disperser, and then a polymerization initiator, a polymerization inhibitor as needed, a leveling agent, etc. are added and the mixture is uniformly stirred to obtain a mixture, and then the mixture is filtered to obtain the ink composition.

[0104] ≪2. Ink Set≫ The above-described active energy ray-curable ink composition may be a colored ink, a clear ink without colorants, a primer ink, or an overcoat ink. The ink set according to this embodiment may be an ink set that combines these ink compositions.

[0105] The ink set according to this embodiment may contain at least one ink composition that includes a specific acylphosphine oxide polymerization initiator A and a polymerization initiator B containing a polycyclic structure, and also contains a polymerizable group-containing modified polysiloxane compound. For example, in an ink set containing ink composition A and ink composition B, ink composition A may be the above-described ink composition, and ink composition B may be a different ink composition. Alternatively, both ink composition A and ink composition B may be the above-described ink composition. The same applies to an ink set containing three or more ink compositions.

[0106] Furthermore, the ink set may be a combination of colored ink compositions containing colorants, for example, a combination of multiple ink compositions selected from yellow, magenta, cyan, black, red, orange, violet, blue, green, intermediate or light colors thereof, a white ink composition containing a white colorant, or a metallic ink containing a glossy colorant.

[0107] ≪3. Recording Method≫ The recording method according to this embodiment is a recording method in which an ink composition containing a polymerizable group-containing modified polysiloxane compound, which contains a specific acylphosphine oxide polymerization initiator A and a polymerization initiator B containing a polycyclic structure, is applied to a substrate by an inkjet method.

[0108] An ink composition containing a specific acylphosphine oxide polymerization initiator A and a polymerization initiator B containing a polycyclic structure, and containing a polymerizable group-containing modified polysiloxane compound, possesses the properties required for active energy ray curable ink compositions, even if the polymerization initiator is not a candidate for listing as a substance of very high concern. Records (printed materials) obtained by the recording method according to this embodiment also possess the required properties.

[0109] The process may also include an irradiation step in which the ink composition applied to the surface of the substrate is irradiated with active energy rays. This irradiation causes a cured product of the ink composition to form on the surface of the substrate. Active energy rays can include electromagnetic waves such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, visible light, infrared rays, X-rays, and gamma rays, as well as electron beams, proton beams, and neutron beams. Among these, active energy rays with a peak wavelength of 365 nm to 395 nm are preferred.

[0110] The light source for irradiating with active energy rays is not particularly limited and includes, for example, high-pressure mercury lamps, metal halide lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, ultraviolet lasers, sunlight, and LED lamps. From the standpoint of energy saving and greater design flexibility for printing equipment, it is more preferable to use LED lamps as the light source.

[0111] To obtain a surface-treated resin substrate, the process may include a pretreatment step in which the surface of the substrate is pre-treated to obtain a surface-treated substrate.

[0112] Examples of surface treatment methods include corona treatment, flame treatment, plasma treatment, fire treatment, ultraviolet irradiation treatment, and silane coupling agent treatment. Two or more surface treatments may be combined.

[0113] The substrate to be pretreated may be either a non-absorbent substrate or an absorbent substrate, as described later.

[0114] Furthermore, the inkjet ejection method for the ink composition may be any method such as a piezo method or an electrostatic method, but a piezo method is preferred. The inkjet printing method may be a serial head method (also called a multi-pass method) or a line head method (also called a single-pass method), and is not particularly limited.

[0115] Alternatively, the ink composition may be applied to the substrate by means other than inkjet, such as a spray or dispenser.

[0116] ≪4. Method of manufacturing printed materials≫ The recording method described above can also be defined as a method for manufacturing printed materials by applying the above-described ink composition onto a substrate using an inkjet method. Alternatively, printed materials can also be manufactured by applying the ink onto the substrate using methods other than inkjet, such as spraying or dispensing.

[0117] ≪5.Printed materials≫ A printed material obtained using the ink composition according to the above embodiment comprises a substrate (recording medium) and a layer of cured material formed on the surface of the substrate (recording medium). This layer of cured material contains a cured polymerizable compound contained in the ink composition according to the above embodiment.

[0118] Here, the polymerizable compound included in the ink composition according to the above embodiment is a polymerization initiator that is not a candidate for listing as a substance of very high concern, yet it possesses the properties required for an active energy ray curable ink composition, and the printed material according to this embodiment also possesses the required properties.

[0119] [Substrate (recording medium)] The substrate (recording medium) included in the printed material according to this embodiment is not particularly limited and may be a non-absorbent substrate such as a resin substrate, a metal plate, or glass, an absorbent substrate such as paper or cloth, or a substrate with a surface coating such as a substrate with a receiving layer, and various substrates can be used.

[0120] Examples of non-absorbent substrates include resin substrates such as polyester resins (polyethylene terephthalate, polyethylene naphthalate), polypropylene synthetic paper, polyolefin resins (polypropylene resins, polyethylene resins, etc.), acrylic resins, polystyrene resins, polycarbonate resins, ABS resins, vinyl chloride resins, and polyimide resins, as well as metals, metal foil coated paper, glass, synthetic rubber, and natural rubber. Among these, it is preferable that the resin substrate contains at least one selected from the group consisting of polypropylene resins, polycarbonate resins, polystyrene resins, polyethylene resins, ABS resins, vinyl chloride resins, polyethylene terephthalate resins, and acrylic resins.

[0121] Absorbent base materials include newsprint, medium-quality paper, fine-quality paper, synthetic paper, cotton, synthetic fiber fabrics, silk, hemp, woven fabrics, nonwoven fabrics, leather, and the like.

[0122] Examples of substrates with surface coatings include coated paper, art paper, cast paper, lightweight coated paper, and lightly coated paper.

[0123] [Cured film of ink composition] The cured film of an ink composition is formed by the polymerization of polymerizable compounds contained in the ink composition. For example, if the ink composition contains a colorant, it becomes a decorative layer or its underlayer that forms a desired image. In this specification, the shape of the "cured film" is not limited to, for example, a flat or layered shape, but may have irregularities, may have pores in some parts, or may have a cured film formed on a part of the surface. Furthermore, for convenience, a cured film of an ink composition that is absorbed by an absorbent substrate and is substantially like a part of the substrate will also be referred to as the cured film of an ink composition.

[0124] The cured film of the ink composition may be a colored layer containing a colorant, or it may be an overcoat layer formed on the surface of the printed material. The printed material according to this embodiment may contain at least one cured film of an ink composition containing a specific acylphosphine oxide polymerization initiator A and a polymerization initiator B containing a polycyclic structure, and containing a polymerizable group-containing modified polysiloxane compound.

[0125] The thickness of the cured product of the ink composition (e.g., the colored layer or the overcoat layer) is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. The thickness of the cured product of the ink composition (e.g., the colored layer or the overcoat layer) is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less. The thickness of the cured product of the ink composition is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 90 μm or less, and even more preferably 5 μm or more and 80 μm or less. Desired functions can be imparted to the cured product of the ink composition. Note that the thickness of the cured product is the average value of the thickness measured at multiple arbitrary locations on the surface of the cured product.

[0126] 6. Inkjet Recording Devices The inkjet recording apparatus according to this embodiment is an inkjet recording apparatus equipped with a storage mechanism filled with an ink composition containing a polymerizable group-containing modified polysiloxane compound, which contains a specific acylphosphine oxide polymerization initiator A and a polymerization initiator B containing a polycyclic structure.

[0127] The inkjet recording apparatus according to this embodiment may be a multi-pass (or serial head) inkjet recording apparatus in which the inkjet head moves back and forth to eject the ink composition, or it may be a single-pass (or line head) inkjet recording apparatus in which the inkjet head does not move to eject the ink composition onto the recording medium (substrate).

[0128] The storage mechanism mounted in the inkjet recording device according to this embodiment is not particularly limited, and examples include containers such as ink bottles, pouches, bag-in-boxes, and drums. Furthermore, these containers may be further housed in cartridges or the like. The material of the storage container is not particularly limited, and may be made of conventionally known resin, or a material that includes some metal material (for example, an aluminum pouch with an aluminum vapor deposition layer).

[0129] Furthermore, the discharge method at each discharge section may be any of the following: piezoelectric, thermal, or electrostatic, but the piezoelectric method is preferred.

[0130] The inkjet recording apparatus according to this embodiment may be equipped with a light source that emits active energy rays. The light source that emits active energy rays is not particularly limited and examples include high-pressure mercury lamps, metal halide lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, ultraviolet lasers, sunlight, LED lamps, etc. From the viewpoint of energy saving and high degree of freedom in the design of the printing apparatus, it is more preferable to use an LED lamp as the light source. [Examples]

[0131] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to these descriptions.

[0132] 1. Manufacturing of ink composition Ink compositions for experimental and comparative examples were prepared. Specifically, the polymerizable monomer, polymerization initiator, polymerization inhibitor, and colorant (pigment mill base) were prepared in the proportions shown in the table below. The units in the table are mass percent.

[0133] 2. Evaluation of the ink composition (Substance of very high concern) We checked whether each component in the ink compositions of the examples and comparative examples contained substances that are candidates for inclusion as substances of very high concern. Specifically, ink compositions that do not contain substances that are candidates for inclusion as "substances subject to authorization" (substances of very high concern) as listed in Annex XIV of the REACH Regulation established by the European Union were designated as "A," and ink compositions that contain substances that are candidates for inclusion as "substances subject to authorization" (substances of very high concern) as listed in Annex XIV of the REACH Regulation established by the European Union were designated as "C."

[0134] (curable) The curability of the ink compositions of the examples and comparative examples was evaluated. Specifically, the ink compositions of the examples and comparative examples were ejected onto the surface of PET film (Toyobo Co., Ltd. Cosmo Shine A4300) using an inkjet recording device, Fujifilm Corporation's "Material Printer DMP-2850," and evaluated with a 385nm wavelength LED lamp at a peak illuminance of 250mW / cm². 2 , cumulative light intensity 650 mJ / cm 2 The ink compositions of the examples and comparative examples were irradiated with active energy rays to produce printed materials. The curability of the produced printed materials was evaluated according to the following evaluation criteria. [Evaluation Criteria] A: Even when I rubbed it with a cotton swab, no ink came off. B: Although it was slightly sticky, no ink came off when I rubbed it with a cotton swab. C: When rubbed with a cotton swab, ink came off. A and B are within the usable range.

[0135] (Breeding) The bleed (smudge-proneness) of the ink compositions of the examples and comparative examples was evaluated. Specifically, the ink compositions of the examples and comparative examples were ejected onto the surface of a PET film (Toyobo Co., Ltd. Cosmo Shine A4300) using an inkjet recording device, Fujifilm Corporation's "Material Printer DMP-2850," so that an image with solid areas containing 6pt characters of a different color was created. The images were then tested using a 385nm wavelength LED lamp with a peak illuminance of 250mW / cm². 2 , cumulative light intensity 650 mJ / cm 2was irradiated with active energy rays to form printed materials of the ink compositions of Examples and Comparative Examples. The bleeding state of the prepared printed materials was observed visually and with a magnifying glass (×20) (denoted as "bleed" in the table). [Evaluation Criteria] A: No ink bleeding is observed under magnifying glass observation. B: Ink bleeding is observed visually, but 6 pt characters can be distinguished. C: Significant ink bleeding is observed visually, and 6 pt characters cannot be recognized.

[0136] (Gloss) Gloss was evaluated for the ink compositions of Examples and Comparative Examples. Specifically, the ink compositions of Examples and Comparative Examples were ejected onto the surface of a PET film (Cosmo Shine A4300, Toyobo Co., Ltd.) using an inkjet recording apparatus, "Material Printer DMP-2850" manufactured by FUJIFILM Corporation, and with an LED lamp having a wavelength of 385 nm, a peak illuminance of 250 mW / cm 2 , an integrated light quantity of 650 mJ / cm 2 was irradiated with active energy rays to prepare a printed material, and the 20° glossiness of the printed material was measured. The glossiness was measured with a handy-type glossmeter Phopoint IQ-S (manufactured by Konica Minolta, Inc.) (denoted as "gloss" in the table). [Evaluation Criteria] A: 20° gloss of 120 or more B: 20° gloss of 100 or more and less than 120 C: 20° gloss of less than 100

[0137] (Substrate Adhesion (PVC)) For the ink compositions of Examples and Comparative Examples, the adhesion of the cured film on a polyvinyl chloride substrate was evaluated. Specifically, the ink compositions of Examples and Comparative Examples were ejected onto the surface of a polyvinyl chloride substrate using an inkjet recording apparatus, "Material Printer DMP-2850" manufactured by FUJIFILM Corporation, and with an LED lamp having a wavelength of 385 nm, a peak illuminance of 250 mW / cm 2 , an integrated light quantity of 650 mJ / cm 2Printed materials were prepared by irradiating them with the active energy rays, and adhesive tape (Nichiban Co., Ltd. Cellotape® CT-18) was attached to the surface. The presence or absence of peeling when the tape was removed was visually checked and evaluated according to the evaluation criteria below (indicated as "Substrate Adhesion (PVC)" in the table). [Evaluation Criteria] A: Almost no peeling occurred. B: Peeling was observed, but it was generally within acceptable limits. C: The area of ​​the peeled surface was more than half the area of ​​the surface to which the adhesive tape was attached. A and B are within the usable range.

[0138] (Adhesion to substrate (PET)) The adhesion of the cured films of the ink compositions in the examples and comparative examples to PET film was evaluated. Specifically, the ink compositions of the examples and comparative examples were ejected onto the surface of PET film (Toyobo Co., Ltd. Cosmo Shine A4360) using an inkjet recording device, Fujifilm Corporation's "Material Printer DMP-2850," and evaluated with a 385nm wavelength LED lamp at a peak illuminance of 250mW / cm². 2 , cumulative light intensity 650 mJ / cm 2 Printed materials were prepared by irradiating them with the active energy rays, and adhesive tape (Nichiban Co., Ltd. Cellotape® CT-18) was attached to the surface. The presence or absence of peeling when the tape was removed was visually checked and evaluated according to the evaluation criteria below (indicated as "Substrate Adhesion (PET)" in the table). [Evaluation Criteria] A: Almost no peeling occurred. B: Peeling was observed, but it was generally within acceptable limits. C: The area of ​​the peeled surface was more than half the area of ​​the surface to which the adhesive tape was attached. A and B are within the usable range.

[0139] (Abrasion-resistant (PVC)) The abrasion resistance (abrasion resistance on a vinyl chloride film) of the ink compositions of the examples and comparative examples was evaluated. Specifically, the ink compositions of the examples and comparative examples were ejected onto the surface of a vinyl chloride film (IMAGin JT5829R: manufactured by MACtac) using an inkjet recording device, Fujifilm Corporation's "Material Printer DMP-2850," and evaluated with a 385nm wavelength LED lamp at a peak illuminance of 250mW / cm². 2 , cumulative light intensity 650 mJ / cm 2 Printed materials were prepared by irradiating them with the active energy rays, and the printed surface of the printed material was rubbed with a test cloth under a load of 200g for 50 back-and-forth strokes, and evaluated according to the evaluation criteria below (indicated as "Abrasion Resistance (PVC)" in the table). [Evaluation Criteria] A: The hardened film hardly peeled off, and there was almost no ink adhering to the test cloth. B: The hardened film peeled off slightly, and a small amount of ink adhered to the test cloth. C: The hardened film peeled off, and ink adhered to the test cloth.

[0140] (Abrasion resistance (PET)) The abrasion resistance (abrasion resistance on PET film) of the ink compositions of the examples and comparative examples was evaluated. Specifically, the ink compositions of the examples and comparative examples were ejected onto the surface of PET film (Toyobo Co., Ltd. Cosmo Shine A4360) using an inkjet recording device, Fujifilm Corporation's "Material Printer DMP-2850," and evaluated with a 385nm wavelength LED lamp at a peak illuminance of 250mW / cm². 2 , cumulative light intensity 650 mJ / cm 2 Printed materials were prepared by irradiating them with the active energy rays, and the printed surface of the printed material was rubbed with a test cloth under a load of 200g for 50 back-and-forth strokes, and evaluated according to the evaluation criteria below (indicated as "Abrasion Resistance (PET)" in the table). [Evaluation Criteria] A: The hardened film hardly peeled off, and there was almost no ink adhering to the test cloth. B: The hardened film peeled off slightly, and a small amount of ink adhered to the test cloth. C: The hardened film peeled off, and ink adhered to the test cloth.

[0141] [Table 1]

[0142] [Table 2]

[0143] [Table 3]

[0144] [Table 4]

[0145] In the table, "A1-1" refers to "isobornyl acrylate (alicyclic structure-containing monomer)". In the table, "A1-2" refers to "4-tert-butylcyclohexyl acrylate (alicyclic structure-containing monomer)". In the table, "A2-1" refers to "cyclic trimethylolpropane formal acrylate (oxygen-containing heterocyclic polymerizable compound)." In the table, "A2-2" refers to "(2-methyl-2-ethyl-1,3-dioxolane-4-yli)methyl acrylate (oxygen-containing heterocyclic polymerizable compound)." In the table, "A2-3" refers to "tetrahydrofurfuryl acrylate (oxygen-containing heterocyclic polymerizable compound)." In the table, "A3-1" refers to "phenoxyethyl acrylate (a polymerizable compound containing aromatic rings)." In the table, "A3-2" refers to "benzyl acrylate (a polymerizable compound containing aromatic rings)." In the table, "A3-3" refers to "phenoxydiethylene glycol acrylate (a polymerizable compound containing aromatic rings)." In the table, "A3-4" refers to "2-hydroxy-3-phenoxypropyl acrylate (a polymerizable compound containing an aromatic ring)." In the table, "A4-1" refers to "N-vinylcaprolactam (a polymerizable compound containing nitrogen-containing heterocyclic compounds)." In the table, "A4-2" refers to "4-acryloylmorpholine (a polymerizable compound containing nitrogen-containing heterocyclic compounds)." In the table, "A4-3" refers to "5-methyl-3-vinyloxazolidine-2-one (polymerizable compound containing nitrogen-containing heterocyclic compounds)." In the table, "A5-1" refers to "N,N-diethylacrylamide (other polymerizable compounds)". In the table, "A5-2" refers to "Tridecylacrylate (other polymerizable compounds)". In the table, "A5-3" refers to "2-(2-ethoxyethoxy)ethyl acrylate (other polymerizable compounds)". In the table, "A6-1" refers to "neopentyl glycol diacrylate (a polyfunctional polymerizable compound)." In the table, "A6-2" refers to "1,6-hexanediol diacrylate (polyfunctional polymerizable compound)". In the table, "A6-3" refers to "1,9-nonanediol diacrylate (polyfunctional polymerizable compound)". In the table, "A6-4" refers to "3-methyl-1,5-pentanediol diacrylate (polyfunctional polymerizable compound)". In the table, "A6-5" refers to "2-(2-vinyloxyethoxy)ethyl acrylate (polyfunctional polymerizable compound)". In the table, "A6-6" refers to "trimethylolpropane triacrylate (a polyfunctional polymerizable compound)." In the table, "A6-7" refers to "dipentaerythritol hexaacrylate (a polyfunctional polymerizable compound)." In the table, "O-1" refers to "Shiko 3300B (acrylate oligomer manufactured by Mitsubishi Chemical)". In the table, "O-2" refers to "CN996NS (Acrylate oligomer manufactured by ARKEMA)". In the table, "O-3" refers to "CN971 (Acrylate oligomer manufactured by ARKEMA)". In the table, "P-1" refers to "Daiso DAP K (diallyl phthalate resin manufactured by Osaka Soda)". In the table, "TMO" refers to "(2,4,6-trimethylbenzoyl)bis(p-tolyl)phosphine oxide (acylphosphine oxide polymerization initiator A represented by formula (3))". In the table, "TPOL" refers to "ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate (acylphosphine oxide polymerization initiator A represented by formula (2))." In the table, "BAPO" refers to "phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (acylphosphine oxide polymerization initiator A represented by formula (1))." In the table, "NPI" refers to "1-(9,9-dibutyl-9H-fluoren-2-yl)-2-methyl-2-(morpholine-4-yl)propan-1-one (polymerization initiator B containing a condensed polycyclic structure represented by formula (4))." In the table, "DETX" refers to "2,4-diethylthioxanthene-9-one (polymerization initiator B containing a polycyclic structure)." In the table, "BMS" refers to "4-benzoyl-4'-methyldiphenyl sulfide (polymerization initiator B containing a polycyclic structure)." In the table, "MBP" refers to "4-methylbenzophenone (polymerization initiator B containing a polycyclic structure)." In the table, "TPO" refers to "2,4,6-trimethylbenzoyldiphenylphosphine oxide (polymerization initiator, candidate for listing as a substance of very high concern)." In the table, "379" refers to "2-(N,N-dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)butan-1-one (polymerization initiator, candidate for inclusion as a substance of very high concern)." In the table, "S1-1" refers to "BYKUV3570 (a modified polysiloxane compound containing polymerizable groups) manufactured by BYK Corporation." In the table, "S1-2" refers to "BYKUV3500 (a modified polysiloxane compound containing polymerizable groups) manufactured by BYK Corporation." In the table, "S1-3" refers to "Tegorad 2010 (a polymerizable group-containing modified polysiloxane compound) manufactured by Evonik." In the table, "S1-4" refers to "TEGO RAD 2300 (a polymerizable group-containing modified polysiloxane compound) manufactured by Evonik." In the table, "S2-1" refers to "BYK390 (non-polymerizable modified polysiloxane compound) manufactured by BYK Corporation." In the table, "S2-2" refers to "KF-6004 (non-polymerizable modified polysiloxane compound) manufactured by Shin-Etsu Chemical Co., Ltd." In the table, "I-1" refers to "Antage TDP (polymerization inhibitor) manufactured by Kawaguchi Chemical Industry Co., Ltd." In the table, "PY155" refers to "CI Pigment Yellow 155 (pigment)". In the table, "PY138" refers to "CI Pigment Yellow 138 (pigment)". In the table, "PR122" refers to "CI Pigment Red 122 (pigment)". In the table, "PV19" refers to "CI Pigment Violet 19 (pigment)". In the table, "PB15:4" refers to "CI Pigment Blue 15:4 (Pigment)". In the table, "PR254" refers to "CI Pigment Red 254 (pigment)". In the table, "PB15:6" refers to "CI Pigment Blue 15:6 (Pigment)". In the table, "PB7" refers to "CI Pigment Black 7 (pigment)". In the table, "PW6" refers to "CI Pigment White 6 (pigment)". In the table, "D-1" refers to "SOLSPERSE 32000 (pigment dispersant) manufactured by Lubrizol Corporation." In the table, "D-2" refers to "SOLSPERSE 33000 (pigment dispersant) manufactured by Lubrizol Corporation." In the table, "D-3" refers to "BYK Disperbykjet 9151 (pigment dispersant)".

[0146] As can be seen from the table above, the ink composition contains a specific acylphosphine oxide polymerization initiator A, along with polymerization initiator B containing a polycyclic structure, and further contains a polymerizable group-containing modified polysiloxane compound. This demonstrates that even if the polymerization initiator is not a candidate for inclusion as a substance of very high concern under the REACH Regulation, the ink composition possesses the properties required for active energy ray curable ink compositions.

Claims

1. An active energy ray curable ink composition for obtaining a record by ejection using an inkjet method, It contains a polymerizable compound and a polymerization initiator. The polymerization initiator is an acylphosphine oxide-based polymerization initiator A, Unlike the acylphosphine oxide polymerization initiator A, it consists only of polymerization initiator B containing a polycyclic structure. Polymerization initiator B containing a polycyclic structure is given by the following general formula (4): The acylphosphine oxide polymerization initiator A contains at least one compound selected from the group consisting of the following general formulas (1), (2), and (3), The polymerizable compound contains a polymerizable group-containing modified polysiloxane compound, The viscosity at 40°C is in the range of 30 mPa·s or less. Ink composition. 【Chemistry 1】 【Chemistry 2】 In formula (2), R １ This is a branched alkyl group having 1 to 10 carbon atoms. 【Transformation 3】 In formula (3), R ２ R is a branched alkyl group having 1 to 10 carbon atoms, ３ This is a branched alkyl group having 1 to 10 carbon atoms. 【Chemistry 4】 In formula (4), R ４ R is a branched alkyl group having 1 to 10 carbon atoms, ５ This is a branched alkyl group having 1 to 10 carbon atoms.

2. The polymerizable compound further contains at least one selected from the group consisting of N-vinyl group-containing polymerizable compounds, vinyl ether group-containing polymerizable compounds, and cyclic structure-containing polymerizable compounds. The ink composition according to claim 1.

3. An ink set comprising the ink composition according to claim 1 or 2.

4. A printed article having the ink composition described in claim 1 or 2 printed on the surface of a substrate.

5. An inkjet recording apparatus comprising a storage mechanism filled with the ink composition according to claim 1 or 2.

6. The ink composition according to claim 1 or 2 is ejected by an inkjet method. Recording method.

7. A printed material is manufactured by ejecting the ink composition described in claim 1 or 2 using an inkjet method. A method for manufacturing printed materials.

Images