Active energy ray curable inkjet printing ink composition

Abstract

To provide an active energy ray curable inkjet printing ink composition that can achieve "improved color reproducibility" of cured coating films (printed materials) while also achieving "reduced gloss." [Solution] An active energy ray curable inkjet printing ink composition containing a colorant, a photopolymerizable monomer including a monofunctional monomer and a difunctional monomer, an amine-modified oligomer, organic fine particles, and a photopolymerization initiator, wherein the ink composition contains 8% by mass or more of a monofunctional monomer having a glass transition temperature of -10°C or lower as the monofunctional monomer; more than 20% by mass and 50% by mass or less of the difunctional monomer as the ink composition; the organic fine particles are organic fine particles with an average particle diameter of 0.2 to 0.8 μm; the content of the organic fine particles is in the range of 1.5 to 5.5% by mass of the ink composition; the content ratio of organic fine particles to the colorant (organic fine particles / colorant component) is 1.6 or less; and the photopolymerization initiator contains an acylphosphine-based initiator, with the content of the acylphosphine-based initiator in the ink composition being in the range of 6.0 to 18.0% by mass.

Description

[Technical Field]

[0001] The present invention relates to an active energy ray curable ink composition for inkjet printing. [Background technology]

[0002] Ink compositions that can be cured by irradiation with active energy rays such as ultraviolet rays or electron beams (active energy ray curable ink compositions) are known. Active energy ray curable ink compositions can be solvent-free (or low-solvent) and are fast-drying, so they can be printed on a variety of substrates. In other words, active energy ray curable ink compositions can prevent ink bleeding even when printed on substrates with low absorbency.

[0003] Active energy ray curable ink compositions are also known to be used as inkjet printing ink compositions. For example, Patent Document 1 discloses an active energy ray curable inkjet ink containing at least a colorant, a monofunctional monomer having a glass transition temperature of less than -25°C, a bifunctional oligomer, a photopolymerization initiator, and a surface tension modifier.

[0004] Furthermore, Patent Document 2 proposes a radical polymerization type UV-curable inkjet ink containing particles (melamine-based particles) with an average particle diameter of 0.4 to 2.5 μm and a refractive index of 1.4 to 1.7. This inkjet ink is said to produce a matte effect by diffusely reflecting light off the surface of the printed material. In addition, Patent Document 3 discloses an active radiation-curable inkjet ink composition containing a colorant, a polymerization initiator, a polymerizable monomer, and crosslinked organic fine particles; this ink composition is said to provide printed materials with good die-cutting characteristics.

[0005] When using active energy ray-curable inkjet ink, a printed material is printed onto the substrate and the printed coating is cured to obtain the printed material. However, when the resulting printed materials are stacked, adhesion marks may remain on the printed surface, or the ink may peel off. This was thought to be due to the poor surface slipperiness of the cured printing film of the active energy ray-curable inkjet ink, causing the stacked printed materials to adhere to each other (blocking). On the other hand, inks containing organic fine particles may have a narrower color gamut and reduced color reproducibility due to the influence of the organic particles.

[0006] To address these issues, Patent Document 4 discloses an active energy ray-curable inkjet printing ink composition containing a colorant, a polymerizable component containing a monofunctional monomer and an amine-modified oligomer, a specific amount of organic fine particles with an average particle size of 0.1 to 0.8 μm, and a surface modifier; which improves the slipperiness of the cured printing film, suppresses blocking, and ensures various properties as an inkjet printing ink (discharge stability, curability, flexibility (stretchability) of the cured printing film, abrasion resistance, and adhesion), thereby maintaining the color gamut of the ink-printed material and improving color reproducibility. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2009-299057 [Patent Document 2] Japanese Patent Publication No. 2019-218435 [Patent Document 3] Japanese Patent Publication No. 2012-025910 [Patent Document 4] Patent No. 7653568 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] As described above, an active energy ray-curable inkjet printing ink composition (see Patent Document 4) containing a colorant, a polymerizable component containing a monofunctional monomer and an amine-modified oligomer, a specific amount of organic fine particles with an average particle size of 0.1 to 0.8 μm, and a surface modifier has been reported to improve the color reproducibility of its cured coating film (printed material); however, it is sometimes required that the cured coating film (printed material) of an active energy ray-curable inkjet printing ink composition have reduced gloss. Therefore, the object of the present invention is to provide an active energy ray-curable inkjet printing ink composition that can achieve both "improved color reproducibility" and "reduced gloss" of the cured coating film (printed material). [Means for solving the problem]

[0009] In other words, the present invention relates to the following active energy ray curable inkjet printing ink composition. [1] An active energy ray-curable inkjet printing ink composition comprising a colorant, a photopolymerizable monomer including a monofunctional monomer and a difunctional monomer, an amine-modified oligomer, organic fine particles, and a photopolymerization initiator, wherein the monofunctional monomer contains 8% by mass or more of a monofunctional monomer having a glass transition temperature of -10°C or lower, relative to the ink composition; the difunctional monomer contains more than 20% by mass and 50% by mass or less, relative to the ink composition; the organic fine particles are organic fine particles with an average particle diameter of 0.2 to 0.8 μm; the content of the organic fine particles is in the range of 1.5 to 5.5% by mass relative to the ink composition; the content ratio of the organic fine particles to the colorant (organic fine particles / colorant component) is 1.6 or less; and the photopolymerization initiator contains an acylphosphine-based initiator, with the content of the acylphosphine-based initiator in the ink composition being in the range of 6.0 to 18.0% by mass.

[0010] Preferably, the present invention relates to the following active energy ray curable inkjet printing ink composition. [2] The active energy ray curable inkjet printing ink composition according to [1], wherein the monofunctional monomer having a glass transition temperature of -10°C or lower is a monofunctional monomer having a glass transition temperature of -20°C or lower. [3] The active energy ray curable inkjet printing ink composition according to [1] or [2], wherein the monofunctional monomer having a glass transition temperature of -10°C or lower comprises one or more selected from ethyl carbitol acrylate, 4-hydroxybutyl acrylate, lauryl acrylate, isodecyl acrylate, and isooctyl acrylate. [4] The active energy ray curable inkjet printing ink composition according to any one of [1] to [3] above, wherein the photopolymerization initiator comprises one or more selected from 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO), 2,4,6-trimethylbenzoyl-xylenyl-phosphine oxide (TMO), ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPOL), and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO). [5] An active energy ray curable inkjet printing ink composition according to any one of [1] to [4], further comprising a surface modifier. [6] The active energy ray curable inkjet printing ink composition according to any one of [1] to [5] above, wherein the coloring agent is a pigment. [7] The active energy ray curable inkjet printing ink composition according to any one of [1] to [6], wherein the amine-modified oligomer is an oligomer having an amino group and two or more functional groups that are crosslinked or polymerized by irradiation with active energy rays within the molecule. [8] A printing ink comprising: step A, which is inkjet coated onto a substrate to be printed with an active energy ray curable ink ink composition according to any one of [1] to [7] above to form a coating film; and step B, which is cured by irradiating the coating film with active energy rays, wherein the integrated amount of active energy rays irradiated in step B is 80 mJ / cm². 2 More than 320mJ / cm2 A method for manufacturing an inkjet printed matter, which is as follows. [Advantages of the Invention]

[0011] The active energy ray-curable ink composition for inkjet printing of the present invention can provide a printed matter with high color reproducibility and suppressed gloss by being cured after inkjet application to a substrate to be printed. [Embodiments for Carrying Out the Invention]

[0012] [1. Composition of the Active Energy Ray-Curable Ink Composition for Inkjet Printing] The active energy ray-curable ink composition for inkjet printing of the present invention (hereinafter sometimes referred to as "ink composition") contains 1) a colorant, 2) a photopolymerizable monomer, 3) an amine-modified oligomer, 4) organic fine particles, and 5) a photopolymerization initiator. Further, the active energy ray-curable ink composition for inkjet printing of the present invention can contain, if necessary, any other components, for example, a pigment dispersant, a surface conditioner, a sensitizer, a polymerization inhibitor, and the like.

[0013] [1-1. Colorant]​​​​​​

[0015] Examples of yellow pigments include, for example, C.I.Pigment Yellow (PY) 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, 213, etc.

[0016] Examples of magenta pigments include, for example, C.I.Pigment Red (PR) 5, 7, 12, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57, 57:1, 63:1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, C.I.Pigment Violet 19, etc.

[0017] Examples of cyan pigments include, for example, C.I.Pigment Blue (PB) 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 22, 27, 29, 60, etc.

[0018] Examples of black pigments include, for example, carbon black (C.I.Pigment Black 7), etc.

[0019] Examples of white pigments include, for example, titanium oxide, aluminum oxide, etc., and they may be surface-treated with various materials such as alumina and silica.

[0020] The content of the pigment in the ink composition varies depending on the type of the pigment and the degree of coloring intended, and is not particularly limited. However, when using a white pigment, it can be about 1 to 20% by mass with respect to the whole ink composition, and when using pigments other than the white pigment, it can be about 0.5 to 15% by mass.

[0021] [1-2. Photopolymerizable monomer] The photopolymerizable monomers contained in the ink composition of the present invention can be broadly classified into A) monofunctional monomers, B) difunctional monomers, and C) polyfunctional monomers with three or more functions.

[0022] [1-2A. Monofunctional monomers] Monofunctional monomers as photopolymerizable monomers are typically compounds having one ethylenically unsaturated bond; they can be broadly classified into nitrogen-containing monofunctional monomers and other monofunctional monomers (unsaturated carboxylic acid compounds, alkyl (meth)acrylate compounds, hydroxyl group-containing (meth)acrylate compounds, halogen-containing (meth)acrylate compounds, ether group-containing (meth)acrylate compounds, carboxyl group-containing (meth)acrylate compounds, other (meth)acrylate compounds, and styrene compounds). In this specification, "(meth)acrylic" means "acrylic and / or methacrylic," and "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid."

[0023] <Nitrogen-containing monofunctional monomers> Nitrogen-containing monofunctional monomers are monofunctional monomers that contain nitrogen atoms in their molecules and can improve the curability of ink compositions. Examples of nitrogen-containing monofunctional monomers include acryloylmorpholine, morpholinoethyl (meth)acrylate, vinylmethyloxazolidinone, vinylcaprolactam, and selected from N,N-dimethyl(meth)acrylamide, acrylonitrile, (meth)acrylamide, diethylacrylamide, diethylaminoethyl (meth)acrylate, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-hydroxymethyl(meth)acrylamide, diacetoneacrylamide, N,N-diethyl(meth)acrylamide, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, dimethylaminoethyl acrylate benzyl chloride quaternary salt, 1-(meth)acryloylpiperidine-2-one, N-(meth)acryloyloxyethylhexahydrophthalimide, imidoacrylate, maleimide, etc. These nitrogen-containing monofunctional monomers can be used individually or in combination of two or more.

[0024] <Unsaturated carboxylic acid compounds> Examples of unsaturated carboxylic acid compounds include (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, fumaric acid, maleic acid, and other unsaturated carboxylic acids, as well as their salts and acid anhydrides.

[0025] <Alkyl (meth)acrylate compounds> Examples of alkyl (meth)acrylate compounds include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and isodecyl (meth)acrylate. Examples include isomiristyl (meth)acrylate, octadecyl (meth)acrylate, dicyclopentanyl (meth)acrylate, tridecyl (meth)acrylate, nonyl (meth)acrylate, hexadecyl (meth)acrylate, myristyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 1-adamantyl (meth)acrylate, 3,5,5-trimethylcyclohexyl acrylate, 4-t-butylcyclohexyl (meth)acrylate, tricyclodecane monomethylol (meth)acrylate, etc.

[0026] <Hydroxyl group-containing (meth)acrylate compounds> Examples of hydroxyl group-containing (meth)acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-1-(meth)acryloxy-3-methacryloxypropane, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 1,4-cyclohexanedimethanol mono(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 Examples include polyalkylene glycol-modified (meth)acrylates such as ylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, 1,6-hexanediol mono(meth)acrylate, glycerin mono(meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxy-3-allyloxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-ethylhexyl EO-modified (meth)acrylate, o-phenylphenol EO-modified (meth)acrylate, p-cumylphenol EO-modified (meth)acrylate, and nonylphenol EO-modified (meth)acrylate.

[0027] <Halogen-containing (meth)acrylate compounds> Examples of halogen-containing (meth)acrylate compounds include tribromophenyl (meth)acrylate, trifluoromethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H-hexafluoroisopropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-heptadecafluorodecyl (meth)acrylate, 2,6-dibromo-4-butylphenyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, and 2,4,6-tribromophenol 3EO (ethylene oxide) addition (meth)acrylate.

[0028] <Ether group-containing (meth)acrylate compounds> Examples of ether group-containing (meth)acrylate compounds include ethyl diglycol acrylate, trimethylolpropane formal (meth)acrylate, 2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 2-(meth)acrylate-1,4-dioxaspiro[4,5]decy-2-ylmethyl, 2-ethylhexyl diglycol (meth)acrylate, 1,3-butylene glycol methyl ether (meth)acrylate, methoxytriethylene glycol (meth)acrylate, Methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, 2-ethylhexyl carbitol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, cresyl polyethylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, p-nonylphenoxyethyl (meth)acrylate, p-nonylphenoxypolyethylene glycol (meth)acrylate, glycidyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxy-polyethylene glycol (meth)acrylate, hexaethylene glycol monophenyl ether mono(meth)acrylate, diethylene glycol monobutyl ether acrylate, dipropylene glycol monomethyl ether (meth)acrylate, 3-methoxybutyl (meth) Acrylate, methoxydiethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate (EO repeating units 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,Examples include alkoxylated 2-phenoxyethyl (meth)acrylate (ethoxylated 2-phenoxyethyl (meth)acrylate, propoxylated 2-phenoxyethyl (meth)acrylate, etc.), alkoxylated nonylphenyl (meth)acrylate (ethoxylated (4) nonylphenol acrylate, etc.), 2-phenoxyethyl (meth)acrylate, paracumylphenoxyethylene glycol (meth)acrylate, methylphenoxyethyl acrylate, ethoxylated succinic acid (meth)acrylate, ethoxylated tribromophenyl acrylate, ethoxylated nonylphenyl (meth)acrylate, and other alkoxy and / or phenoxy (meth)acrylates.

[0029] <Carboxyl group-containing (meth)acrylate compounds> Examples of carboxyl group-containing (meth)acrylate compounds include β-carboxyethyl (meth)acrylate, monoacryloyloxyethyl succinate, ω-carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hexahydrohydrogen phthalate, 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate, acryloyloxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, 2-(meth)acryloyloxyethyl succinic acid, and 2-(meth)acryloyloxyethyl hexahydrophthalic acid.

[0030] <Other (meth)acrylate compounds> Other (meth)acrylate compounds include, for example, benzyl acrylate, trimethylsiloxyethyl (meth)acrylate, diphenyl-2-(meth)acryloyloxyethyl phosphate, 2-(meth)acryloyloxyethyl acid phosphate, caprolactone-modified-2-(meth)acryloyloxyethyl acid phosphate, (meth)acrylate dimer, cresol (meth)acrylate, neopentyl glycol (meth)acrylate benzoate, and γ-butyrolactone (meth)acrylate.

[0031] <Styrene-based compounds> Examples of styrene-based compounds include styrene, vinyltoluene, p-hydroxystyrene, p-chlorostyrene, p-bromostyrene, p-methylstyrene, p-methoxystyrene, pt-butoxystyrene, pt-butoxycarbonylstyrene, pt-butoxycarbonyloxystyrene, 2,4-diphenyl-4-methyl-1-pentene, and divinylbenzene.

[0032] As a compound having one ethylenically unsaturated bond, "other compounds having one ethylenically unsaturated bond" other than the aforementioned compounds can be used. Examples of such compounds include vinyl acetate, monochlorovinyl acetate, vinyl benzoate, vinyl pivalate, vinyl butyrate, vinyl laurate, divinyl adipate, vinyl crotonate, vinyl 2-ethylhexanoate, three-membered ring compounds (e.g., vinylcyclopropanes, 1-phenyl-2-vinylcyclopropanes, 2-phenyl-3-vinyloxiranes, 2,3-divinyloxiranes, etc.), cyclic ketene acetals (e.g., 2-methylene-1,3-dioxepane, posioxolanes, 2-methylene-4-phenyl-1,3-dioxepane, 4,7-dimethyl-2-methylene-1,3-dioxepane, 5,6-benzo-2-methylene-1,3-dioxepane, etc.).

[0033] <Low Tg monofunctional monomers> Some or all of the monofunctional monomers used as photopolymerizable monomers are monofunctional monomers having a glass transition temperature of -10°C or lower (also called "low Tg monofunctional monomers"), preferably monofunctional monomers having a glass transition temperature of -20°C or lower, and may also be monofunctional monomers having a glass transition temperature of -30°C or lower. By making at least some of the monofunctional monomers low Tg monofunctional monomers, the gloss of the cured coating film of the ink composition can be reduced.

[0034] Examples of low Tg monofunctional monomers include ethyl carbitol acrylate (Tg: -54°C), 4-hydroxybutyl acrylate (Tg: -32°C), lauryl acrylate (Tg: -30°C), lauryl methacrylate (-65°C), isodecyl acrylate (Tg: -60°C), isooctyl acrylate (Tg: -54°C), tridecyl acrylate (Tg: -55°C), and tridecyl methacrylate (Tg: -4°C). These include low-Tg monofunctional monomers (Tg: -15°C), tetrahydroflyl acrylate (Tg: -53°C), caprolactone acrylate (Tg: -53°C), alkoxylated 2-phenoxyethyl acrylate (Tg: -23.5°C), methoxypolyethylene glycol monomethacrylate (Tg: -60°C or below), ethoxylated 2-phenol acrylate (Tg: -13°C), ethoxylated 4-phenol acrylate (Tg: -32°C), etc. Low-Tg monofunctional monomers can be used alone or in combination of two or more.

[0035] The content of low-Tg monofunctional monomers in the ink composition of the present invention is 8% by mass or more, preferably 10% by mass or more, more preferably 12% by mass or more, and even more preferably 15% by mass or more. The monofunctional monomers in the present invention may include other monofunctional monomers in addition to low-Tg monofunctional monomers.

[0036] The total content of monofunctional monomers in the ink composition of the present invention is preferably 25% by mass or more, more preferably 30% by mass or more, and may be 35% by mass or more, relative to the total content of the ink composition; on the other hand, it is preferably 70% by mass or less, and more preferably 60% by mass or less. Since the ink composition of the present invention can contain relatively hard organic fine particles, it is preferable to make the curing resin, which consists of polymerizable components contained in the ink composition, a relatively flexible resin in order to improve the overall stretchability of the cured printed film.

[0037] [1-2B.2 Functional Monomers] The bifunctional monomer used as a polymerizable component is a monomer having two ethylenically unsaturated bonds, and examples include bifunctional (meth)acrylate compounds and vinyl ether group-containing (meth)acrylate compounds.

[0038] Examples of difunctional monomers 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, butylene glycol di(meth)acrylate, pentyl glycol di(meth)acrylate, and neopentyl glycol. Di(meth)acrylate, hydroxypivalyl hydroxypivalate di(meth)acrylate, hydroxypivalyl hydroxypivalate dicaprolactone di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,2-hexanediol di(meth)acrylate, 1,5-hexanediol di(meth)acrylate, 2,5-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,2-octanediol di(meth)acrylate acrylate, 1,9-nonanediol di(meth)acrylate, 1,2-decanediol di(meth)acrylate, 1,10-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-hexadecanediolic acid di(meth)acrylate, 1,2-hexadecanediolic acid di(meth)acrylate, 2-methyl-2,4-pentanediol All di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-2-propyl-1,3-propanediol di(meth)acrylate, 2,4-dimethyl-2,4-pentanediol di(meth)acrylate, 2,2-diethyl-1,3-propanediol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, dimethylol octanedi(meth)acrylate, 2-ethyl-1,3-hexanediol di(meth)acrylate, 2,5-dimethyl-2,5-Hexanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 2,4-diethyl-1,5-pentanediol di(meth)acrylate, tricyclodecanedimethylol di(meth)acrylate, tricyclodecanedimethylol dicaprolactone di(meth)acrylate, bisphenol A tetraethylene oxide adduct di(meth)acrylate, bisphenol F tetraethylene oxide adduct di(meth)acrylate Examples include bisphenol S tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol F tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol F di(meth)acrylate, bisphenol A tetraethylene oxide adduct dicaprolactone di(meth)acrylate, and bisphenol F tetraethylene oxide adduct dicaprolactone di(meth)acrylate.

[0039] The difunctional monomer may also be a vinyl ether group-containing (meth)acrylate compound; examples include (meth)acrylate-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 Ropil, (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-4-vinyloxymethylcyclohexylmethyl, (meth) 3-vinyloxymethylcyclohexylmethyl lylate, 2-vinyloxymethylcyclohexylmethyl (meth)acrylate, p-vinyloxymethylphenylmethyl (meth)acrylate, m-vinyloxymethylphenylmethyl (meth)acrylate, o-vinyloxymethylphenylmethyl (meth)acrylate, 2-(vinyloxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxy)propyl (meth)acrylate, 2- Examples include (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-2-(vinyloxyisopropoxyisopropoxy)ethyl, (meth)acrylate-2-(vinyloxyisopropoxyisopropoxy)ethyl, and (meth)acrylate vinyl.

[0040] The content of the difunctional monomer in the ink composition of the present invention is more than 20% by mass, preferably 25% by mass or more, and more preferably 30% by mass or more, relative to the ink composition; on the other hand, it is preferably 50% by mass or less, and 45% by mass or less. By setting the content of the difunctional monomer to more than 20% by mass or more relative to the ink composition, the resistance (including abrasion resistance and water resistance) of the cured coating film of the ink composition of the present invention can be improved. On the other hand, by setting the content of the difunctional monomer to a certain level or less, the gloss of the cured coating film can be appropriately suppressed.

[0041] [1-2C, 3- or more polyfunctional monomers] Polyfunctional (meth)acrylate compounds with three or more functions are monomers possessing three or more ethylenically unsaturated bonds, such as tri(meth)acrylate compounds with three or more functions.

[0042] Examples of trifunctional monomers include trimethylolpropane EO-modified tri(meth)acrylate, glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tricaprolactone tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolhexane tri(meth)acrylate, trimethyloloctan tri(meth)acrylate, and pentaerythritol tri(meth)acrylate.

[0043] Examples of monomers with four or more functionalities include pentaerythritol tetra(meth)acrylate, pentaerythritol tetracaprolactone tetra(meth)acrylate, diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ditrimethylolpropane tetracaprolactone tetra(meth)acrylate, ditrimethylolethane tetra(meth)acrylate, ditrimethylolbutane tetra(meth)acrylate, and ditrimethylol Examples include hexanetetra(meth)acrylate, ditrimethyloloctanetetra(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.

[0044] The content of the polyfunctional monomer with three or more functions in the ink composition of the present invention may be 0, but may be 1% by mass or more, 2% by mass or more, or 3% by mass or more relative to the ink composition; on the other hand, it may be 10% by mass or less. Including polyfunctional monomers with three or more functions may improve the abrasion resistance and water resistance of the printed cured product.

[0045] [1-3. Reactive Oligomers (Amine-Modified Oligomers)] The ink composition of the present invention contains a reactive oligomer as a polymerizable component. A reactive oligomer is an oligomer having one or more polymerizable functional groups (ethylenically unsaturated bonds) in its molecule, and the ethylenically unsaturated bonds in the molecule polymerize to become high molecular weight. Since the oligomer is a relatively high molecular weight component before polymerization, it can impart appropriate viscosity and elasticity to the ink composition. In addition, the oligomer is relatively polar, which may impart adhesion to non-absorbent substrates to the cured ink composition.

[0046] The reactive oligomers contained in the ink composition include amine-modified oligomers. Amine-modified oligomers are reactive oligomers having two or more amino groups and functional groups that crosslink or polymerize upon irradiation with active energy rays within their molecule. Preferably, amine-modified oligomers have two amino groups and two functional groups that crosslink or polymerize upon irradiation with active energy rays within their molecule. Amine-modified oligomers are also sometimes referred to as reactive amine co-initiators, reactive amine synergists, acrylate-modified amine synergists, amine acrylates, etc.

[0047] The viscosity of the reactive oligomer (preferably an amine-modified oligomer) is not limited, but it is particularly preferable that the viscosity at 25°C be 2000 cps or less in order to bring the overall viscosity of the ink composition within an appropriate range.

[0048] The content of amine-modified oligomers in the ink composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to the total polymerizable components of the ink composition; on the other hand, it is preferably 20% by mass or less, more preferably 17% by mass or less, and even more preferably 13% by mass or less. By setting the content of amine-modified oligomers to 0.5% by mass or more, the curability of the ink composition can be improved and blocking of the cured printed material can be suppressed. Furthermore, by setting the content of amine-modified oligomers to 20% by mass or less, the viscosity of the ink composition can be suppressed to improve discharge stability, while making it easier to ensure the stretchability of the cured printed film.

[0049] Amine-modified oligomers are also available from the market. Examples of amine-modified oligomers available on the market include CN371, CN373, CN383, CN386, CN501, CN550, and CN551 from Sartomer; EBECRYL80 and EBECRYL7100 from Daicel Ornex; GENOMER5142, GENOMER 5161, and GENOMER 5275 from RAHN; Miramer AS2010 and Miramer AS5142 from Miwon; and Etercure 641, Etercure 6410, Etercure 6411, Etercure 6412, Etercure 6413, Etercure 6417, Etercure 6420, Etercure 6422, Etercure 6423, Etercure 6425, and Etercure from Changxing Chemical Co., Ltd. Examples of preferred amine-modified oligomers include 6430, Etercure 645, and Etercure 647. Examples of preferred amine-modified oligomers include acrylic amine compounds such as CN371, CN373, CN383, and CN386 (manufactured by Sartomer), with CN371, CN386 (manufactured by Sartomer), EBECRYL80 (manufactured by Daicel Ornex), etc., having two or more photopolymerizable functional groups in the molecule being even more preferred.

[0050] [1-4.Organic fine particles] The organic fine particles contained in the ink composition of the present invention are preferably made of resin. The average particle size of the organic fine particles is 0.2 μm or more, preferably 0.3 μm or more; on the other hand, it is 0.8 μm or less, preferably 0.6 μm or less. When the average particle size of the organic fine particles is 0.2 μm or more, it is easy to reduce the gloss of the cured printed material of the ink composition and easy to improve the slipperiness and blocking resistance of the cured printed material; when it is 0.8 μm or less, it is easy to maintain the ejection stability of the ink composition. The average particle size of the organic fine particles can be measured by a particle size distribution analyzer that uses the laser diffraction scattering method as its measurement principle. An example of a particle size distribution analyzer is a particle size distribution analyzer that uses the dynamic light scattering method as its measurement principle (such as the Microtrac UPA manufactured by Nikkiso Co., Ltd.).

[0051] The resin constituting the organic microparticles may be a crosslinked resin or a non-crosslinked resin. Compared to organic microparticles made of a non-crosslinked resin, organic microparticles made of a crosslinked resin have higher physical strength (hardness, etc.), making it easier to improve the slipperiness and blocking resistance of cured printed materials containing them. Furthermore, because organic microparticles made of a crosslinked resin do not swell easily in the ink composition, the stability of the ink composition can be improved.

[0052] Specific examples of resins that make up organic fine particles include polymethyl methacrylate, acrylic resin, styrene-acrylic copolymer, melamine resin, polycarbonate, styrene resin, cross-linked polystyrene, polyvinyl chloride, benzoguanamine-melamineformaldehyde resin, fluororesin, silicone (silicon) resin, and melamine / silica composite particles.

[0053] The organic microparticles may be those available on the market. Examples of organic microparticles that can be used include Nippon Paint's FineSphere® series, which consists of acrylic resin or styrene-acrylic copolymer; Nippon Shokubai's Epostor® series, which consists of melamine resin; Fujikura Chemical's FFP series, which consists of acrylic resin; and Nissan Chemical's OptoBeads® series, which consists of melamine / silica composite particles.

[0054] The content of organic fine particles in the ink composition is 1.5% by mass or more, preferably 1.8% by mass or more, and more preferably 2.0% by mass or more, relative to the mass of the ink composition; on the other hand, it is 5.5% by mass or less, preferably 5.0% by mass or less, and more preferably 4.5% by mass or less. By setting the content of organic fine particles to 1.5% by mass or more, it is easier to obtain the effect of reducing the gloss of the cured printed material, and it is also possible to improve the slipperiness and blocking resistance of the cured printed material. Furthermore, by setting the content of organic fine particles to 5.5% by mass or less, the discharge stability of the ink composition can be ensured.

[0055] The ink composition of the present invention contains organic fine particles, which can reduce the gloss of cured printed materials and improve their slipperiness and blocking resistance; however, the color gamut of the cured coating film produced by the ink composition may be narrowed, resulting in a decrease in color reproducibility in the cured printed materials. For example, the inclusion of organic fine particles may narrow the human color perception threshold (the range of color space that a person can recognize as a color tone that should be imparted by the colorant of the ink composition).

[0056] Therefore, in the ink composition of the present invention, it is preferable to broaden the color gamut of the ink composition by adjusting the relative content ratio of organic fine particles to a colorant (preferably a pigment). Specifically, the mass content of organic fine particles in the ink composition is 1.6 or less, preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.0 or less, relative to the mass content of the colorant (preferably a pigment); on the other hand, it is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more. By setting the content ratio of organic fine particles to the colorant to 1.6 or less, the color gamut of the ink composition can be broadened and color reproducibility can be improved.

[0057] Furthermore, it is preferable that the organic fine particles contained in the ink composition are localized on the surface (the surface opposite to the surface in contact with the substrate) when the ink composition is printed on the substrate and cured. Localization of the organic fine particles on the surface of the cured coating film tends to improve the slipperiness and blocking resistance of the printed material. For this reason, it is preferable that the specific gravity of the organic fine particles be low; specifically, it is preferable that the true specific gravity of the organic fine particles be 2.1 or less, and more preferably 2.0 or less.

[0058] [1-5. Photopolymerization Initiators] The photopolymerization initiator contained in the ink composition of the present invention hardens the ink composition when it is irradiated with ultraviolet light, LED, or the like. The photopolymerization initiator generates active species such as radicals when irradiated with active energy rays, and initiates the photopolymerization of the active energy ray curable composition. Examples of photopolymerization initiators include acylphosphine oxide compounds, triazine compounds, aromatic ketone compounds, aromatic onium salt compounds, organic peroxides, thioxanthone compounds, thiophenyl compounds, anthracene compounds, hexaarylbisimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, halogenated hydrocarbon compounds and alkylamine compounds, iodonium salt compounds and sulfonium salt compounds, etc.

[0059] The photopolymerization initiator is, in part or in whole, an acylphosphine oxide compound. When a predetermined amount of an acylphosphine oxide compound is incorporated as a photopolymerization initiator, it contributes to suppressing the gloss of the cured printed material and further enhances the curability of the ink composition of the present invention. The mechanism of gloss suppression by the acylphosphine oxide compound is not particularly limited, but it can be considered that controlling the curing behavior of the polymerizable component can impart surface roughness to the coating film, leading to gloss suppression.

[0060] The content of acylphosphine oxide compounds in the ink composition is 6.0% by mass or more, preferably 8.0% by mass or more, while it is 18.0% by mass or less, and preferably 15.0% by mass or less.

[0061] Examples of acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPOL), and 2,4,6-trimethylbenzoyl-xylenyl-phosphine oxide (TMO); these can be used individually or in combination of two or more.

[0062] The photopolymerization initiator may contain other photopolymerization initiators along with the acylphosphine oxide compound. Specific examples of other photopolymerization initiators include benzophenone, diethylthioxanthone, 2-methyl-1-(4-methylthio)phenyl-2-morpholinopropan-1-one, 4-benzoyl-4'-methyldiphenyl sulfide, 1-chloro-4-propoxythioxanthone, isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2,2-dimethyl-2-hydroxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and 2-benzyl-2-dimethylamino-1-(morpholinophenyl)-butan-1-one.

[0063] The total content of the photopolymerization initiator in the ink composition is 6.0% by mass or more, preferably 8.0% by mass or more, while it is 18.0% by mass or less, and preferably 15.0% by mass or less.

[0064] [1-6. Other ingredients] [1-6-1. Surface modifiers] The ink composition of the present invention may contain a surface modifier. By using organic fine particles and a surface modifier in the ink composition, the slipperiness and blocking resistance are further improved. Furthermore, the surface modifier can enhance the ejection stability of the ink composition. Examples of surface modifiers include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants, and silicone-based surfactants. On the other hand, it is preferable that the surface modifier is not a polymer-based additive.

[0065] Specific examples of silicone-based surfactants used as surface modifiers include polyether-modified silicone oils such as hydroxyl-containing polyether-modified polydimethylsiloxane and polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane and polyester-modified methylalkylpolysiloxane. Silicone-based surfactants are also available from the market as BYK-307, BYK-315, BYK-315N, BYK-331, BYK-333, BYK-347, BYK-348, BYK-349, BYK-345, BYK-377, BYK-378, BYK-3455, BYK3760, BYK3764 (BYK), Tegorad2250, Tegorad2300 (EVONIK), etc.

[0066] The content of the surface modifier in the ink composition is preferably in the range of 0.05 to 2.50% by mass relative to the ink composition.

[0067] [1-6-2. Sensitizers] The ink composition of the present invention may contain a sensitizer. The sensitizer can improve the curability of the ink composition. Examples of sensitizers include anthracene-based sensitizers such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene; and thioxanthone-based sensitizers such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. The sensitizer is preferably a thioxanthone-based sensitizer. The content of the sensitizer in the ink composition is, for example, about 0.1 to 5% by mass.

[0068] [1-6-3. Polymerization inhibitors] The ink composition of the present invention may contain a polymerization inhibitor. The polymerization inhibitor can suppress unintended polymerization reactions (such as polymerization reactions that occur without irradiation with active energy rays). Examples of polymerization inhibitors include hydroquinone, dibutylhydroxytoluene, hydroquinone monomethyl ether, and phenothiazine. The content of the polymerization inhibitor in the ink composition is, for example, about 0.01 to 5.0% by mass.

[0069] [1-6-4. Pigment Dispersants] If the ink composition of the present invention contains a pigment, it may further contain a pigment dispersant for dispersing the pigment. The pigment dispersant is preferably a polymer-based pigment dispersant, and more preferably a pigment dispersant containing a basic group. Examples of pigment dispersants containing a basic group include polymer-based pigment dispersants such as basic group-containing polyester-based pigment dispersants, basic group-containing acrylic-based pigment dispersants, basic group-containing urethane-based pigment dispersants, and basic group-containing carbodiimide-based pigment dispersants, as well as anionic surfactants.

[0070] Polymeric pigment dispersants are not particularly limited, but may be linear polymers having a pigment-affinity moiety consisting of basic groups at least at the ends of the main chain (one or both ends) by a block or graft structure. Polymeric pigment dispersants can contain 2 to 3,000 basic groups per molecule, and their number-average molecular weight may be 1,000 to 1,000,000.

[0071] The pigment dispersant content in the ink composition is preferably 1.0 to 200.0 parts by mass, based on a total pigment content of 100 parts by mass.

[0072] [1-6-5. Other Additives] Other additives may include solvents, UV absorbers, antioxidants, defoamers, preservatives, mold inhibitors, rust inhibitors, thickeners, humectants, pH adjusters, and various other additives. The amount of solvent in the ink composition is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, even more preferably 2.0% by mass or less, and may not be included at all.

[0073] [2. Preparation of the ink composition] The ink composition of the present invention can be prepared according to conventionally known methods. For example, the components can be dispersed and mixed using a disperser such as a wet circulation mill, bead mill, ball mill, sand mill, attritor, roll mill, DCP mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, high-pressure homogenizer (microfluidizer, nanomizer, ultimateizer, Genus PY, DeBEE2000, etc.), or pearl mill, and the viscosity can be adjusted as necessary to obtain the ink composition.

[0074] Furthermore, the ink composition of the present invention can also be prepared by first obtaining a base ink composition by mixing a colorant (such as a pigment), organic fine particles, and some polymerizable components, and then adding the remaining components to achieve the desired composition. In addition, if the ink composition contains a pigment, a base ink composition containing the pigment and a pigment dispersant can be prepared, and organic fine particles may or may not be incorporated into the base ink composition.

[0075] [3. Inkjet Printing of Ink Compositions] The ink composition of the present invention can be used to inkjet print an inkjet printed material onto a substrate to be printed. In other words, the method for producing an inkjet printed material according to the present invention comprises: step A, which is inkjet coated onto a substrate to be printed to form a coating film; and step B, which is irradiated with active energy rays to cure the coating film.

[0076] [3-1. Process A] The ink coating of the ink composition in step A can be performed using an inkjet printing device. The type of inkjet printing device that can be used is not particularly limited; it may be a line head type (single pass type) or a serial head type (multi-pass type). A continuous type inkjet printing device may also be used, in which case a conductivity imparting agent can be added to further adjust the conductivity of the ink composition.

[0077] The ink composition is supplied to the printer head of an inkjet printing device, and the printer head ejects the ink composition onto the substrate to be printed. The ejection of the ink composition from the printer head onto the substrate (printing of an image) should be performed so that the thickness of the coating on the substrate is, for example, 1 to 60 μm.

[0078] The substrate to be printed on is not particularly limited, and is not limited to any substrate to which a conventionally known photocurable inkjet printing ink composition can be applied. Examples of substrates include plastics, paper, capsules, gels, metal foils, glass, wood, and cloth. The cured coating film of the ink composition of the present invention has excellent abrasion resistance and stretchability. Therefore, it is sometimes preferable to print the ink composition of the present invention on a flexible substrate, such as a plastic film.

[0079] Examples of plastics constituting the substrate to be printed include one or more selected from the group consisting of polyester polymers (e.g., polyethylene terephthalate (PET), polyethylene naphthalate, etc.), cellulosic polymers (e.g., diacetylcellulose, triacetylcellulose (TAC), etc.), polycarbonate polymers, polyacrylic polymers (e.g., polymethyl methacrylate, etc.), vinyl chloride polymers, polyolefin polymers (e.g., polyethylene, polypropylene, polyolefin polymers having a cyclic or norbornene structure, ethylene-propylene copolymer polymers, etc.), polyamide polymers (e.g., nylon, aromatic polyamide polymers, etc.), polystyrene polymers (e.g., polystyrene, acrylonitrile-styrene copolymer polymers, etc.), polyimide polymers, polysulfone polymers, polyethersulfone polymers, polyetherketone polymers, polyphenyl sulfide polymers, polyvinyl alcohol polymers, polyvinylidene chloride polymers, polyvinyl butyral polymers, polyarylate polymers, polyoxymethylene polymers, and polyepoxy polymers, as well as blends of these polymers.

[0080] [3-2. Process B] The ink film formed on the substrate to be printed is cured by irradiation with active energy rays to produce an inkjet printed material. Examples of active energy rays include ultraviolet light, electron beams, and visible light emitted from light-emitting diodes (LEDs), various lamps, and electrodes. From an environmental perspective, it is preferable to use a light-emitting diode (LED) that generates ultraviolet light with an emission peak wavelength in the range of 350-420 nm as the light source. The amount of active energy rays irradiated in step B is not particularly limited. Multiple irradiations may be performed to impart resistance to the cured film. For example, the coated area can be pinned before overall irradiation. The integrated light intensity of the irradiated light is 80 mJ / cm². 2 More than 320mJ / cm 2 The following is preferable: By adjusting the integrated amount of irradiated active energy rays, the suppression of gloss in printed materials can be enhanced.

[0081] [4. Uses of inkjet printed materials] The ink composition of the present invention, as an active energy ray curable inkjet printing ink composition, ensures the necessary properties while also providing high physical properties of the cured coating film (scratch resistance, solvent resistance, slipperiness, blocking resistance, and stretchability) due to the inclusion of organic fine particles. In addition, it offers high color reproduction and suppressed gloss in printed materials, making it applicable to a wide range of uses as an inkjet printing ink composition. For example, it can be used for printing on film, paper, metal plates, etc., for use in sign displays and commercial printing. [Examples]

[0082] The present invention will be described more specifically below with reference to examples. However, the technical scope of the present invention is not to be limited in any way by these examples.

[0083] A. Preparation of ink compositions for inkjet printing Inkjet printing ink compositions for each example and comparative example were prepared according to the composition formulations shown in Tables 1 to 4 (the amount of each component is shown in parts by mass). The raw material components used in the preparation are shown below.

[0084] A-1. Colorants (coloring pigments) • Phthalocyanine blue pigment PB15:4 • Quinacridone magenta pigment PR122 • Disazo yellow pigment PY155 • Carbon Black PBk7

[0085] A-2. Photopolymerizable monomers <monofunctional monomers> A-2-1. Low Tg monofunctional monomers • Ethyl carbitol acrylate (Tg: -54℃) • 4-Hydroxybutyl acrylate (Tg: -32℃) • Lauryl acrylate (Tg: -30℃)

[0086] A-2-2. Other monofunctional monomers MEDOL-10 (Tg: -7℃): (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate Phenoxyethyl acrylate (Tg: 2℃) • Benzyl acrylate (Tg: 6℃) Isobornyl acrylate (Tg: 97℃) VMOX (Tg: 120℃): Vinylmethyloxazolidinone • Acryloylmorpholin (Tg: 145℃)

[0087] A-3. Photopolymerizable monomers <bifunctional monomers> PEG400 diacrylate (Tg: -33℃) • 1,6-Hexanediol diacrylate (Tg: 43℃) PEG200 diacrylate (Tg: 45℃) • Tripropylene glycol diacrylate (Tg: 55℃) • PO-modified neopentyl glycol diacrylate (Tg: 60℃) 3-methyl-1,5-pentanediol diacrylate • Dipropylene glycol diacrylate (Tg: 105℃)

[0088] A-4. Photopolymerizable monomers <Polyfunctional monomers with three or more functions> Trimethylolpropane EO-modified triacrylate (Tg: 40°C) • Dipentaerythritol hexaacrylate

[0089] A-5. Amine-modified oligomers • CN371 (Sartomer): Amine-modified oligomer (difunctional)

[0090] A-6.Organic fine particles A-6-1. Average particle size within the range of 0.2 to 0.8 μm • FFP-8300 (Fujikura Chemical): Acrylic resin particles, particle size 0.3 μm • FFP-8301 (Fujikura Chemical): Acrylic resin particles, particle size 0.5 μm • FS-501 (Nippon Paint): Acrylic resin particles, particle size 0.5 μm • FS-201 (Nippon Paint): Styrene-acrylic fine particles, particle size 0.5 μm • Epostor S (Nippon Shokubai): Melamine resin particles, particle size 0.2 μm • Epostor S6 (Nippon Shokubai): Melamine resin particles, particle size 0.4 μm • Optobeads 500S (Nissan Chemical): Melamine / silica composite microparticles, particle size 0.5 μm

[0091] A-6-2. Outside the range of average particle size 0.2~0.8 μm • Eposter SS (Nippon Shokubai): Melamine resin particles, particle size 0.1 μm • Epostor S12 (Nippon Shokubai): Melamine resin particles, particle size 1.2 μm • FDB-001 (Fujikura Chemical): Acrylic microparticles, particle size 0.9 μm • FS-301 (Nippon Paint): Styrene-acrylic fine particles, particle size 1.0 μm • Epostor MV1002 (Nippon Shokubai): Acrylic resin microparticles, particle size 2μm • Optobeads 2000M (Nissan Chemical): Melamine-silica composite microparticles, particle size 2.0 μm

[0092] A-7. Photopolymerization initiator A-7-1. Acylphosphine Oxide System TPO:2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide • TMO: 2,4,6-trimethylbenzoylxylenylphosphine oxide • TPOL: Ethyl phenyl(2,4,6-trimethylbenzoyl) phosphinate • BAPO: Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide

[0093] A-7-2. Other photopolymerization initiators • Omnirad 184 (IGM.Resin): 1-Hydroxycyclohexyl-phenyl ketone • Omnirad MBF (IGM.Resin): Methylbenzoyl formate • ESACURE KIP160 (DKSH): Bifunctional α-hydroxyketone type

[0094] A-8. Others (surface modifiers, polymerization inhibitors, sensitizers, pigment dispersants) • BYK-377 (BYK): Polyether-modified hydroxyl-containing polydimethylsiloxane • Igastab UV-22 (BASF): Polymerization inhibitor • DETX: 2,4-diethylthioxanthone (sensitizer) • Solspers SS32000 (Lubrizol): Pigment dispersant • Ajisper PB821 (Ajinomoto Fine Techno Co., Ltd.): Pigment dispersant

[0095] Using the components described above, inkjet printing ink compositions for each example and comparative example in Tables 1 to 4 were prepared. In other words, each inkjet printing ink composition was prepared by blending, dispersing, and stirring the components according to the formulation compositions shown in Tables 1 to 4. Specifically, a pigment dispersion (the pigment dispersion contained the pigment, pigment dispersant, and some polymerizable components, and sometimes organic fine particles) was prepared, and then mixed with the remaining components to prepare the ink composition.

[0096] In addition, ink compositions without organic fine particles were similarly prepared for each example and comparative example of inkjet printing ink composition and used for the evaluation of "B-6. Gloss" and "B-7. Color Gamut" described later.

[0097] B. Evaluation of ink compositions and their cured printed materials The ink compositions prepared in each example and comparative example, and the printed materials (cured coatings of the printed materials) thereof, were evaluated based on the following points, and the evaluation results are shown in Tables 1 to 4.

[0098] B-1. Discharge Stability of Ink Composition Each ink composition prepared in the examples and comparative examples was continuously printed (printed) onto a substrate: polyvinyl chloride film (PVC80, manufactured by Lintec Corporation) using an inkjet recording device equipped with an inkjet nozzle, and its ejection stability was evaluated according to the following evaluation criteria. ○: Printing is consistent and stable. △: There are some minor printing irregularities, but the print output is stable. ×: Printing is irregular or the material cannot be ejected consistently.

[0099] B-2. Curability of the ink composition Each ink composition prepared in the examples and comparative examples was applied to a substrate: PVC board (T938, manufactured by Takiron CI Co., Ltd.) using a bar coater No. 6. Then, using a conveyor-type light irradiation device (STM-250E-16, manufactured by Heraeus, Inc., lamp: Z-8 lamp (metal halide type)), the light was irradiated at 120W × 50m / min, with an integrated UV light intensity of 75mJ / cm². 2 [The UV integrated light dose was determined by measuring the irradiation dose at the following ranges: 250-260 nm, 280-320 nm, 320-390 nm, and 395-445 nm using an EIT UVIMAP (UM365H-S) as the measuring instrument] and this was considered one pass, during which the coating film was irradiated with light and cured. After each pass, the coating film was rubbed with a cotton swab, and the curability was evaluated according to the following criteria. ○: After 3 passes, no uncured ink adheres to the cotton swab, and no marks are left on the coating from rubbing with the cotton swab. △: After 6 passes, no uncured ink adheres to the cotton swab, and no marks are left on the coating from rubbing with the cotton swab. ×: After 6 passes, uncured ink adheres to the cotton swab, or marks from rubbing with a cotton swab remain on the paint film.

[0100] B-3. ​​Abrasion resistance of printed materials Each ink composition prepared in the examples and comparative examples was printed onto a PVC board (T938, manufactured by Takiron CI Co., Ltd.), and an integrated light intensity of 100 mJ / cm² was measured using an LED lamp with an emission peak wavelength of 395 nm. 2 Pinning irradiation was performed, followed by an integrated light intensity of 500 mJ / cm². 2 A cured coating was created by light irradiation. The created coating was then visually observed to see how much of the coating was removed when rubbed with a bleaching cloth at 60 rpm for 100 times with 500g of material using a JSPS-type friction fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho), and evaluated according to the following criteria. ○: No paint film has been removed. △: The paint film surface has scratches. ×: Shows clear signs of paint film removal.

[0101] B-4. Water resistance of printed materials Each ink composition prepared in the examples and comparative examples was printed on a PVC plate (T938 manufactured by Takiron Shiaei Co., Ltd.), and pinned irradiation was performed using an LED lamp with a peak emission wavelength of 395 nm at an integrated light quantity of 100 mJ / cm 2 followed by light irradiation at an integrated light quantity of 500 mJ / cm 2 to form a cured coating film. The obtained cured coating film was visually observed for the condition of the coating film being rubbed off when rubbed with a sun-exposed cloth containing water at 200 g × 10 times and 30 rpm using a Kagaku Shinku Seisakusho Co., Ltd.-manufactured Gakushin-type friction fastness tester, and evaluated according to the following criteria. 〇: No rubbing off of the coating film. ×: Obvious rubbing off of the coating film is observed.

[0102] B-5. Blocking resistance of printed matter Each ink composition prepared in the examples and comparative examples was printed on a PET film, and pinned irradiation was performed using an LED lamp with a peak emission wavelength of 395 nm at an integrated light quantity of 100 mJ / cm 2 followed by light irradiation at an integrated light quantity of 500 mJ / cm 2 to form a cured coating film. The obtained cured coating film was cut into a size of 4 × 5 cm 2 and the ink surface of the cured coating film was overlapped with the PET film, and the sticking state of the coating film after applying a load of 2 kg for 1 day was confirmed. 〇: There are no adhesion marks on the coating film, and it can be peeled off without resistance. △: There are some adhesion marks on the coating film, or there is peeling resistance when peeled off. ×: There are adhesion marks on the coating film, and the ink peels off when peeled off.

[0103] B-6. Gloss Each ink composition obtained in the examples and comparative examples and an ink composition not containing organic fine particles were printed in solid printing (printing) at 100% on a substrate: polyvinyl chloride film (PVC80, manufactured by Lintec Corporation) using an inkjet recording apparatus equipped with an inkjet nozzle, and pinned irradiation was performed using an LED lamp with a peak emission wavelength of 395 nm at an integrated light quantity of 100 mJ / cm​​​Printed materials were obtained by irradiating them with light. The gloss of the printed surface of the obtained printed materials was measured using a gloss meter (HORIBA Gloss Checker IG-340, incident angle 60°). The difference in gloss value (ΔGLOSS) of the obtained printed materials was determined for each ink composition obtained in the examples and comparative examples, and for the corresponding ink composition without organic fine particles, and the gloss was evaluated under the following conditions. 〇:20≦ΔGLOSS △: 10 ≤ ΔGLOSS < 20 ×:ΔGLOSS <10

[0104] B-7. Color gamut Each ink composition obtained in the examples and comparative examples, and ink compositions without organic fine particles, were 100% solid printed onto a substrate: polyvinyl chloride film (PVC80, manufactured by Lintec Corporation) using an inkjet recording device equipped with an inkjet nozzle, and an integrated light intensity of 100 mJ / cm² was measured using an LED lamp with an emission peak wavelength of 395 nm. 2 Pinning irradiation was performed, followed by an integrated light intensity of 500 mJ / cm². 2 Printed materials were obtained by irradiating them with light. The color values ​​of the printed surface of the obtained printed materials were measured using a colorimeter (X-Rite spectrophotometer, eXact) under conditions of a viewing angle of 2° and a light source D50. The difference in color values ​​(color difference ΔE) of the obtained printed materials was determined for each ink composition obtained in the examples and comparative examples, and for the corresponding ink composition without organic fine particles, and the color gamut was evaluated under the following conditions. 〇:ΔE≦5 △:5<ΔE≦10 ×: 10 < ΔE

[0105] [Table 1]

[0106] [Table 2]

[0107] [Table 3]

[0108] [Table 4]

[0109] Examples 1-25 (Tables 1-3) all received a sufficiently high evaluation for all evaluation items.

[0110] In Comparative Example 1, the average particle size of the organic fine particles (Epostor SS) contained in it was 0.1 μm, which is below 0.2 μm, and the gloss of the cured coating film was not suppressed. In Comparative Examples 2 to 6, the average particle size of the organic fine particles contained in them (Epostor S12, FDB-001, FS-301, Epostor MV1002, Optobeads 2000M) exceeded 0.8 μm, resulting in a decrease in the color gamut evaluation of the cured coating film and deterioration of the discharge stability. Thus, it can be seen that by adjusting the average particle size of the organic fine particles, it is possible to achieve both gloss suppression and color gamut expansion of the cured coating film.

[0111] Comparative Example 7 contained no organic fine particles, while Comparative Example 8 contained 1.0% by mass of organic fine particles, which is below 1.5% by mass, resulting in reduced abrasion resistance and blocking resistance. Furthermore, the cured coating film of Comparative Example 7 was visibly more glossy compared to the example. Comparative Example 9 contained 8.0% by mass of organic fine particles, which is above 5.5% by mass, resulting in reduced color gamut evaluation of the cured coating film and decreased discharge stability. Thus, it can be seen that by adjusting the content of organic fine particles, it is possible to achieve both gloss suppression and color gamut expansion of the cured coating film.

[0112] Comparative Example 10 had an organic fine particle content ratio of 1.7 relative to the pigment, which was higher than 1.6, resulting in a decrease in color gamut evaluation. This demonstrates that reducing the organic fine particle content ratio relative to the pigment can expand the color gamut.

[0113] Comparative Example 11 had an acylphosphine-based photopolymerization initiator (TMO) content of 4.0% by mass, which was below 6.0% by mass, resulting in poor curability of the ink composition and reduced abrasion resistance and blocking resistance of the cured coating film. Comparative Example 12 had an acylphosphine-based photopolymerization initiator (TMO) content of 20.0% by mass, which was above 18.0% by mass, resulting in insufficient gloss suppression.

[0114] Comparative Example 13 did not contain difunctional monomers, while Comparative Example 14 contained 15.0% by mass of difunctional monomers, which is below 20% by mass. As a result, the water resistance of the cured coating film deteriorated, and its abrasion resistance and blocking resistance also decreased. Comparative Example 15 contained 55.0% by mass of difunctional monomers, which is above 50% by mass. As a result, the gloss suppression of the cured coating film was insufficient. Thus, by including a predetermined amount of difunctional monomers, it is possible to achieve gloss suppression while improving various resistances of the cured coating film.

[0115] Comparative Example 16 did not contain an amine-modified oligomer, resulting in insufficient curability of the ink composition and deterioration of various resistances of the cured coating film (scratch resistance, water resistance, and blocking resistance).

[0116] Comparative Examples 17-19 contained 5.0% by mass of low-Tg monofunctional monomers, which is below 8% by mass. This resulted in insufficient gloss suppression of the cured coating film and reduced curability of the ink composition. Thus, including low-Tg monofunctional monomers (monofunctional monomers with a glass transition temperature of -10°C or lower) can promote gloss suppression of the cured coating film.

[0117] Examples 1-25 (Tables 1-3) received more than satisfactory evaluations for all evaluation items. First, as shown in Examples 1-4, satisfactory evaluations were obtained for all types of pigments (cyan, magenta, yellow, black) in all evaluation categories.

[0118] As shown in Examples 1 and 5-7, sufficient evaluations were obtained in all evaluations even when the content of organic fine particles (FFP-8300) was changed from 1.5% by mass to 4.5% by mass. However, in Example 5, where the content of organic fine particles was 1.5% by mass, gloss suppression of the cured coating film was slightly more difficult, and abrasion resistance and blocking resistance were also slightly reduced. In Example 7, where the content of organic fine particles was 4.5% by mass, the color gamut evaluation of the cured coating film was slightly reduced.

[0119] As shown in Examples 1 and 8-13, by including 10 or 12% by mass of an acylphosphine-based initiator (TPO, TMO, TPOL, BAPO) as a photopolymerization initiator, good evaluation results were obtained for all evaluation items. In Example 14, the acylphosphine-based initiator (TPOL) content was 6% by mass, and the abrasion resistance and blocking resistance of the cured coating film were slightly reduced. In Example 15, the acylphosphine-based initiator (TPOL) content was 18% by mass, and in Example 16, the acylphosphine-based initiator (TPOL) content was 15% by mass, and both contained a combination of three types of low-Tg monofunctional monomers, but the gloss suppression of these cured coating films became slightly more difficult. Thus, by adjusting the content of the acylphosphine-based initiator, it is possible to suppress gloss while improving various resistances of the cured coating film.

[0120] Example 17 contains 44.0% by mass of a difunctional monomer (3-methyl-1,5-pentanediol diacrylate) and 10.0% by mass of a low-Tg monofunctional monomer (ethyl carbitol acrylate), which slightly reduced the gloss suppression of the cured coating film.

[0121] In Example 18, the amine-modified oligomer content was 0.5% by mass, resulting in reduced curability of the ink composition. In Example 19, the amine-modified oligomer content was 15.0% by mass, and a combination of three low-Tg monofunctional monomers was included, but good results were obtained in all evaluation items.

[0122] As shown in Examples 1 and 20-25, good results were obtained for all evaluation items even when the organic fine particles contained therein were changed. However, in Example 23, which contained the organic fine particle Epostor S (average particle size 0.2 μm), it became slightly more difficult to suppress the gloss of the cured coating film. [Industrial applicability]

[0123] By manufacturing printed materials using the active energy ray curable inkjet printing ink of the present invention, the cured coating film exhibits high resistance to various factors (including abrasion resistance, water resistance, and blocking resistance), high color reproduction of the printed material, and suppression of gloss. Therefore, it can be applied to a wide range of applications as an inkjet printing ink. For example, it can be used for printing on film, paper, metal plates, etc., for use in sign displays and commercial printing.

Claims

1. An active energy ray curable inkjet printing ink composition comprising a colorant, a photopolymerizable monomer including monofunctional and difunctional monomers, an amine-modified oligomer, organic fine particles, and a photopolymerization initiator: The ink composition contains 8% by mass or more of a monofunctional monomer having a glass transition temperature of -10°C or lower, as the monofunctional monomer. The aforementioned difunctional monomer is contained in an amount of 21% by mass or more and 50% by mass or less relative to the ink composition. The aforementioned organic fine particles are organic fine particles with an average particle size of 0.2 to 0.8 μm. The content of the organic fine particles is in the range of 1.5 to 5.5% by mass relative to the ink composition. The content ratio of the organic fine particles to the coloring agent (organic fine particles / coloring agent component) is 1.6 or less. An active energy ray curable inkjet printing ink composition wherein the photopolymerization initiator contains an acylphosphine-based initiator, and the content of the acylphosphine-based initiator in the ink composition is in the range of 6.0 to 18.0% by mass.

2. The active energy ray curable inkjet printing ink composition according to Claim 1, wherein the difunctional monomer is contained in an amount of 25% by mass or more relative to the ink composition.

3. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the monofunctional monomer having a glass transition temperature of -10°C or lower is a monofunctional monomer having a glass transition temperature of -20°C or lower.

4. The active energy ray-curable inkjet printing ink composition according to claim 1 or 2, wherein the monofunctional monomer having a glass transition temperature of -10°C or lower comprises one or more selected from ethyl carbitol acrylate, 4-hydroxybutyl acrylate, lauryl acrylate, isodecyl acrylate, and isooctyl acrylate.

5. The active energy ray-curable inkjet printing ink composition according to claim 1 or 2, wherein the photopolymerization initiator comprises one or more selected from 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (TPO), 2,4,6-trimethylbenzoyl-xylenyl-phosphine oxide (TMO), ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide (TPOL), and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO).

6. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, further comprising a surface modifier.

7. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the coloring agent is a pigment.

8. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the amine-modified oligomer is an oligomer having an amino group and two or more functional groups that are crosslinked or polymerized by irradiation with active energy rays within its molecule.

9. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the monofunctional monomer has a glass transition temperature of -10°C or lower and contains 70% by mass or less of the ink composition.

10. The invention comprises the steps of: A) applying the active energy ray-curable inkjet printing ink composition according to claim 1 or 2 to a substrate to be printed using an inkjet printer to form a coating film; and B) curing the coating film by irradiating it with active energy rays. The integrated amount of the active energy rays irradiated in step B is 80 mJ / cm². ２ More than 320mJ / cm ２ The following is a method for manufacturing inkjet printed materials.

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