Active energy ray-curable inkjet-printing ink composition

Abstract

The present invention addresses a problem of, in relation to an active energy ray-curable inkjet-printing ink composition, ensuring various characteristics (discharge stability, curability, flexibility (stretchability) of a cured printed film, scratch resistance, and adhesion) as an inkjet-printing ink while improving slidability of the cured printed film and suppressing blocking. Preferably, the present invention addresses a problem of, in relation to an active energy ray-curable inkjet-printing ink composition containing organic fine particles, maintaining the color gamut of an ink-printed matter and improving color reproducibility. As a solution to the problems, provided is an active energy ray-curable inkjet-printing ink composition comprising: a colorant; a polymerizable component containing a monofunctional monomer and an amine modified oligomer; organic fine particles; and a surface modifier. The organic fine particles have an average particle diameter of 0.1-0.8 µm. The contained amount of the organic fine particles is 1.2-8 mass% with respect to the ink composition. The content ratio (organic fine particles / colorant component) of the organic fine particles to the colorant component is not more than 1.5.

Description

Ink composition for active energy ray-curable inkjet printing

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

[0002] Active energy ray-curable ink compositions (active energy ray-curable ink compositions) that can be cured by irradiating active energy rays such as ultraviolet rays and electron beams are known. Since the active energy ray-curable ink composition can be solvent-free (or low-solvent) and has quick drying properties, it can be printed on various printing substrates. That is, even when the active energy ray-curable ink composition is printed on a printing substrate with low absorbency, effects such as preventing ink bleeding can be obtained.

[0003] It is also known to use an active energy ray-curable ink composition as an ink composition for inkjet printing. 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 photoinitiator, and a surface tension modifier.

[0004] Further, Patent Document 2 proposes a radical polymerization type ultraviolet curable inkjet ink containing particles (melamine-based particles) having an average particle diameter of 0.4 to 2.5 μm and a refractive index of 1.4 to 1.7. The inkjet ink is said to exhibit a matte effect by diffusely reflecting the surface of the printed matter. Patent Document 3 also discloses an active radiation curable inkjet ink composition containing a colorant, a polymerization initiator, a polymerizable monomer, and crosslinked organic fine particles; it is said that a printed matter with good punching characteristics can be provided using the ink composition.

[0005] JP-A-2009-299057 JP-A-2019-218435 JP-A-2012-025910

[0006] 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, it was found that inks containing organic fine particles may have a narrower color gamut and reduced color reproducibility due to the influence of the organic fine particles.

[0007] The object of the present invention is to improve the slipperiness of the cured print film and suppress blocking in an active energy ray curable inkjet printing ink composition, while ensuring various properties as an inkjet printing ink (discharge stability, curability, flexibility (stretchability), abrasion resistance, and adhesion of the cured print film). More preferably, the object of the present invention is to maintain the color gamut of the ink-printed material and improve color reproducibility in an active energy ray curable inkjet printing ink composition containing organic fine particles.

[0008] 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 polymerizable component containing a monofunctional monomer and an amine-modified oligomer, organic fine particles, and a surface modifier, wherein the organic fine particles are organic fine particles with an average particle diameter of 0.1 to 0.8 μm; the content of the organic fine particles is 1.2 to 8% by mass relative to the active energy ray-curable inkjet printing ink composition; and the content ratio of the organic fine particles to the colorant component (organic fine particles / colorant component) is 1.5 or less.

[0009] Furthermore, the present invention preferably relates to the following inkjet printing ink compositions: [2] The active energy ray curable inkjet printing ink composition according to [1], wherein the average particle size of the organic fine particles is 0.5 μm or less. [3] The active energy ray curable inkjet printing ink composition according to [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 the molecule. [4] The active energy ray curable inkjet printing ink composition according to any one of [1] to [3], wherein the content of the amine-modified oligomer is 0.5 to 20% by mass with respect to the total amount of the polymerizable components. [5] The active energy ray curable inkjet printing ink composition according to any one of [1] to [4], wherein the content of the monofunctional monomer is 60% by mass or more with respect to the total amount of the polymerizable components. [6] The active energy ray-curable inkjet printing ink composition according to any one of [1] to [5], wherein the polymerizable component contains a polyfunctional monomer, and the content of the polyfunctional monomer is 2 to 40% by mass relative to the total amount of the polymerizable component. [7] The active energy ray-curable inkjet printing ink composition according to any one of [1] to [6], wherein the organic fine particles are fine particles of a crosslinked polymer. [8] The active energy ray-curable inkjet printing ink composition according to any one of [1] to [7], wherein the organic fine particles are melamine-based fine particles. [9] The active energy ray-curable inkjet printing ink composition according to any one of [1] to [8], wherein the surface modifier is a silicone-based surface modifier.

[10] The active energy ray-curable inkjet printing ink composition according to any one of [1] to [9], wherein the coloring agent component is a pigment.

[0010] The active energy ray-curable inkjet printing ink composition of the present invention possesses various characteristics as an inkjet printing ink (discharge stability, curability, flexibility (stretchability) of the cured printing film, abrasion resistance, and adhesion), while forming a cured printing film with excellent slipperiness and blocking resistance. Furthermore, despite containing organic fine particles, the active energy ray-curable inkjet printing ink composition of the present invention has a wide color gamut, and therefore exhibits high color reproducibility.

[0011] [1. Composition of Active Energy Ray Curable Inkjet Printing Ink Composition] The active energy ray curable inkjet printing ink composition of the present invention (hereinafter sometimes referred to as the ink composition) contains 1) a colorant, 2) a polymerizable component, 3) organic fine particles, and 4) a surface modifier. The active energy ray curable inkjet printing ink composition of the present invention may also contain any other components as needed, such as a photopolymerization initiator, a sensitizer, a polymerization inhibitor, a pigment dispersant, etc.

[0012] [1-1. Colorants] The colorants contained in the ink composition of the present invention are components added to the ink composition to impart coloring power, opacity, etc. The colorants may be pigments or dyes, but pigments are preferred. Examples of pigments include coloring pigments, white pigments, extender pigments, metal powders (aluminum paste, bronze powder, etc.), and the following organic and / or inorganic pigments can be listed without particular limitation.

[0013] Examples of pigments include dye lake pigments, azo, benzimidazolone, phthalocyanine, quinacridone, anthraquinone, dioxazine, indigo, thioindico, perylene, perinone, diketopyrrolopyrrole, isoindolinone, nitro, nitroso, flavanthrone, quinophthalone, pyranthrone, and indanthrone organic pigments, as well as various inorganic pigments.

[0014] Examples of yellow pigments include 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, and 213.

[0015] Examples of magenta pigments include 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, and C. I. Pigment Violet 19.

[0016] Examples of cyan pigments include C.I. Pigment Blue (PB) 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 22, 27, 29, and 60.

[0017] Examples of black pigments include carbon black (C.I. Pigment Black 7).

[0018] Examples of white pigments include titanium dioxide and aluminum oxide, and these may be surface-treated with various materials such as alumina and silica.

[0019] The pigment content in the ink composition varies depending on the type of pigment and the desired degree of coloring, and is not particularly limited. However, when using white pigment, it may be approximately 1 to 20% by mass, and when using pigments other than white pigment, it may be approximately 0.5 to 15% by mass of the total ink composition.

[0020] [1-2. Polymerizable Components] The polymerizable components contained in the ink composition of the present invention can be broadly classified into A) monofunctional monomers, B) polyfunctional monomers, and C) reactive oligomers.

[0021] [1-2A. Monofunctional Monomers] Monofunctional monomers as polymerizable components 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).

[0022] <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 acryloyl morpholine, vinylmethyl oxazolidinone, vinyl caprolactam, and selected from N,N-dimethylacrylamide, acrylonitrile, (meth)acrylamide, diethylacrylamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-hydroxymethyl(meth)acrylamide, diacetoneacrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, lactone-modified flexible acrylates, etc. These nitrogen-containing monofunctional monomers can be used alone or in combination of two or more. In this specification, "(meth)acrylic" means "acrylic and / or methacrylic," and "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid."

[0023] <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.

[0024] <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, i Examples include sodecyl (meth)acrylate, 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, and 4-t-butylcyclohexyl (meth)acrylate.

[0025] <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, 4-hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, 2-hydroxy-3-methoxypropyl (meth)acrylate, 2-hydroxy-3-butoxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polypropylene Examples include polyalkylene glycol-modified (meth)acrylates such as ylene 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.

[0026] <Halogen-containing (meth)acrylate compounds> Examples of halogen-containing (meth)acrylate compounds include trifluoromethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H-hexafluoroisopropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-heptadecafluorodecyl (meth)acrylate, 2,6-dibromo-4-butylphenyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, and 2,4,6-tribromophenol 3EO (ethylene oxide)-added (meth)acrylate.

[0027] <Ether group-containing (meth)acrylate compounds> Examples of ether group-containing (meth)acrylate compounds include 1,3-butylene glycol methyl ether (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, 2-ethylhexyl carbitol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, cresyl polyethylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, p-nonylphenoxyethyl (meth)acrylate, p-nonylphenoxypolyethylene glycol (meth)acrylate, glycidyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxy-polyethylene glycol (meth)acrylate, hexaethylene glycol monophenyl ether mono(meth)acrylate, and diethylene glycol monobutyl ether acrylate. Lilate, 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 Phenoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, alkoxylated 2-phenoxyethyl (meth)acrylate (ethoxylated 2-phenoxyethyl (meth)acrylate, propoxylated 2-phenoxyethyl (meth)acrylate, etc.), alkoxylated nonylphenyl (meth)acrylate (ethoxylated (4) nonylphenol acrylate, etc.), 2-phenoxyethyl (meth)acrylate, paracumylphenoxyethylene glycol (meth)acrylate, methylphenoxyethyl acrylate,Examples include alkoxy and / or phenoxy (meth)acrylates such as ethoxylated succinic acid (meth)acrylate, ethoxylated tribromophenyl acrylate, and ethoxylated nonylphenyl (meth)acrylate.

[0028] <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, and 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate.

[0029] <Other (meth)acrylate compounds> Other (meth)acrylate compounds include, for example, benzyl acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, acryloylmorpholine, morpholinoethyl (meth)acrylate, trimethylsiloxyethyl (meth)acrylate, diphenyl-2-(meth)acryloyloxyethyl phosphate, 2-(meth)acryloyloxyethyl acid phosphate, caprolactone-modified-2-(meth)acryloyl Xyethyl acid phosphate, 2-hydroxy-1-(meth)acryloxy-3-methacryloxypropane, acrylicoxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, tricyclodecane monomethylol (meth)acrylate, (meth)acrylate dimer, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hex Sahydrophthalic acid, 2-ethylhexyl-diglycol (meth)acrylate, aminoethyl (meth)acrylate, ethyl carbitol acrylate, ethyl diglycol acrylate, dimethylaminoethyl acrylate benzyl chloride quaternary salt, tribromophenyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, cresol (meth)acrylate, trimethylolpropaneformal (meth)acrylate, neopentyl glycol (meth)acrylic acid Examples include benzoic acid esters, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 1-(meth)acryloylpiperidine-2-one, 2-(meth)acrylate-1,4-dioxaspiro[4,5]decy-2-ylmethyl, N-(meth)acryloyloxyethylhexahydrophthalimide, γ-butyrolactone (meth)acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, imide acrylate, vinyl (meth)acrylate, maleimide, etc.

[0030] <Styrene-based compounds> Examples of styrene-based compounds include styrene, vinyltoluene, p-hydroxystyrene, p-chlorostyrene, p-bromostyrene, p-methylstyrene, p-methoxystyrene, p-t-butoxystyrene, p-t-butoxycarbonylstyrene, p-t-butoxycarbonyloxystyrene, 2,4-diphenyl-4-methyl-1-pentene, and divinylbenzene.

[0031] 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, vinyl monochloroacetate, vinyl benzoate, vinyl pivalate, vinyl butyrate, vinyl laurate, divinyl adipate, vinyl crotonate, vinyl 2-ethylhexanoate, three-membered ring compounds (e.g., vinylcyclopropanes, 1-phenyl-2-vinylcyclopropanes, 2-phenyl-3-vinyloxiranes, 2,3-divinyloxiranes, etc.), and 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.).

[0032] These monofunctional monomers can be used individually or in combination of two or more.

[0033] The monofunctional monomers included in the ink composition preferably include nitrogen-containing monofunctional monomers. The glass transition temperature of the monofunctional monomer (and the glass transition temperature of its homopolymer) is not particularly limited and may be, for example, in the range of -100°C to +200°C.

[0034] The content of monofunctional monomers in the ink composition is preferably 60% by mass or more, more preferably 70% by mass or more, relative to the total amount of polymerizable components; on the other hand, it is preferably 95% by mass or less, more preferably 90% 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 cured resin consisting of polymerizable components contained in the ink composition a relatively flexible resin in order to improve the overall stretchability of the cured printed film.

[0035] [1-2B. Polyfunctional Monomers] Polyfunctional monomers as polymerizable components are monomers having two or more ethylenically unsaturated bonds, and for example, polyfunctional (meth)acrylate compounds and vinyl ether group-containing (meth)acrylate compounds can be used. The polyfunctional (meth)acrylate compounds may be bifunctional di(meth)acrylate compounds, trifunctional tri(meth)acrylate compounds, or polyfunctional (meth)acrylate compounds with more than two functions.

[0036] 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, 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, 1,2-Hexanediol di(meth)acrylate, 1.5-Hexanediol di(meth)acrylate, 2.5-Hexanediol di(meth)acrylate, 2-methyl-2,4-pentanedi(meth)acrylate, 2.4-diethyl-1,5-pentanediol di(meth)acrylate, tricyclodecanedimethylol di(meth)acrylate, tricyclodecanedimethylol dicaprolactone di(meth)acrylate, bisf Examples include bisphenol A tetraethylene oxide adduct di(meth)acrylate, bisphenol F tetraethylene oxide adduct di(meth)acrylate, bisphenol S tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A tetraethylene oxide adduct di(meth)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.

[0037] 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.

[0038] 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.

[0039] The polyfunctional monomer may 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-vinyl Xyxypropyl, 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)acrylate , (meth)acrylate-3-vinyloxymethylcyclohexylmethyl, (meth)acrylate-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 Examples include (t) 2-(vinyloxyethoxy)isopropyl acrylate, (meth) 2-(vinyloxyisopropoxy)propyl meth) acrylate, (meth) 2-(vinyloxyisopropoxy)isopropyl meth) acrylate, (meth) 2-(vinyloxyethoxyethoxy)ethyl meth) acrylate, (meth) 2-(vinyloxyisopropoxyethoxy)ethyl meth) acrylate, (meth) 2-(vinyloxyisopropoxyisopropoxy)ethyl meth) acrylate, etc.

[0040] The ink composition of the present invention may or may not contain a polyfunctional monomer. However, from the viewpoints of the scratch resistance and solvent resistance of the printed cured product, it preferably contains a polyfunctional monomer of 2% by mass or more, more preferably 3% by mass or more, still more preferably 4% by mass or more, based on the total mass of the polymerizable components; on the other hand, it preferably contains a polyfunctional monomer of 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less. By setting the content of the polyfunctional monomer to 2% by mass or more, the scratch resistance and solvent resistance of the cured printed film can be improved; on the other hand, when it exceeds 40% by mass, the flexibility (stretchability) of the cured printed film tends to decrease.

[0041] [1-2C. Reactive oligomer] The ink composition of the present invention contains a reactive oligomer as a polymerizable component. A reactive oligomer is an oligomer having one or two or more polymerizable functional groups (ethylenically unsaturated bonds) in the molecule, and the ethylenically unsaturated bonds contained in the molecule polymerize to increase the molecular weight. Since the oligomer is a component having a relatively high molecular weight before polymerization, it can impart appropriate viscosity and elasticity to the ink composition. In addition, the oligomer has a relatively high polarity and may impart adhesion to a non-absorbent printed substrate of the ink composition after curing.

[0042] The reactive oligomer contained in the ink composition is preferably an amine-modified oligomer. An amine-modified oligomer is a reactive oligomer having two or more amino groups and functional groups that crosslink or polymerize by irradiation with active energy rays in the molecule. The amine-modified oligomer is preferably a reactive oligomer having two amino groups and two functional groups that crosslink or polymerize by irradiation with active energy rays in the molecule. The amine-modified oligomer may also be referred to as a reactive amine co-initiator, reactive amine synergist, acrylate-modified amine synergist, amine acrylate, etc.

[0043] The viscosity of the reactive oligomer (preferably an amine-modified oligomer) is not limited. In particular, when the viscosity at 25 °C is 2000 cps or less, it is preferable in order to make the viscosity of the entire ink composition within an appropriate range.

[0044] 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.

[0045] 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, GENOMER5161, and GENOMER5275 from RAHN; Miramer AS2010 and Miramer AS5142 from Miwon; and Etercure 641, Etercure 6410, Etercure 6411, Etercure 6412, Etercure 6413, and Etercure from Changxing Chemical Co., Ltd. This includes 6417, Etercure 6420, Etercure 6422, Etercure 6423, Etercure 6425, Etercure 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.

[0046] [1-3. Organic Fine Particles] The organic fine particles contained in the ink composition of the present invention are preferably particles made of resin. The average particle diameter of the organic fine particles is 0.1 μm or more; on the other hand, it is 0.8 μm or less, and preferably 0.5 μm or less. When the average particle diameter of the organic fine particles is 0.1 μm or more, it is easy to improve the slipperiness and blocking resistance of the cured print of the ink composition; when it is 0.8 μm or less, it is easy to maintain the discharge stability of the ink composition. The average particle diameter of the organic fine particles can be measured by a particle size distribution measuring device using the laser diffraction scattering method as the measurement principle. Examples of the particle size distribution measuring device include a particle size distribution meter (such as Microtrack UPA manufactured by Nikkiso Co., Ltd.) using the dynamic light scattering method as the measurement principle.

[0047] The resin constituting the organic fine particles may be a crosslinked resin or a non-crosslinked resin. The organic fine particles of the crosslinked resin have higher physical strength (such as hardness) compared to the organic fine particles of the non-crosslinked resin, and it is easy to improve the slipperiness and blocking resistance of the cured print containing it. In addition, the organic fine particles of the crosslinked resin are difficult to swell in the ink composition, so the stability of the ink composition can be enhanced.

[0048] Specific examples of the resin constituting the organic fine particles include polymethyl methacrylate, acrylic resin, acrylic-styrene copolymer, melamine resin, polycarbonate, styrene resin, crosslinked polystyrene, polyvinyl chloride, benzoguanamine-melamine formaldehyde resin, silicone (silicon) resin, etc. Among them, the melamine resin, which is a crosslinked resin, is preferred.

[0049] The content of organic fine particles in the ink composition is preferably 1.2% by mass or more, more preferably 1.5% 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 preferably 8% by mass or less, and more preferably 5% by mass or less. By setting the content of organic fine particles to 1.2% by mass or more, the slipperiness and blocking resistance of the cured printed material can be improved, and the gloss of the cured printed material can also be reduced. Furthermore, by setting the content of organic fine particles to 8% by mass or less, the discharge stability of the ink composition can be ensured.

[0050] The ink composition of the present invention, by containing organic fine particles, may improve the slipperiness and blocking resistance of cured printed materials and further reduce gloss; however, it has been found that the color gamut of the ink composition may be narrowed, resulting in a decrease in color reproducibility in 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 the color tone to be imparted by the colorant of the ink composition).

[0051] Therefore, in the ink composition of the present invention, it is preferable to adjust the relative content ratio of organic fine particles to a colorant (preferably a pigment) to broaden the color gamut of the ink composition. Specifically, the mass content of organic fine particles in the ink composition is 1.5 or less, preferably 1.2 or less, and 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 1.5 or less, the color gamut of the ink composition can be broadened and color reproducibility can be improved.

[0052] 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 printed material) 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.

[0053] [1-4. Surface Modifiers] The ink composition of the present invention contains a surface modifier. By using organic fine particles and a surface modifier in combination 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.

[0054] 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 (BYK Corporation), etc.

[0055] 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.

[0056] [1-5. Any other components] [1-5A. Photopolymerization initiator] The ink composition of the present invention may contain a photopolymerization initiator. In particular, if the ink composition is cured by irradiation with ultraviolet light or LED light, it is preferable to contain a photopolymerization initiator. On the other hand, if the ink composition is cured by irradiation with electron beam light, it usually does not contain a photopolymerization initiator.

[0057] Photopolymerization initiators generate active species such as radicals upon irradiation with active energy rays, thereby initiating the photopolymerization of active energy ray-curable compositions. 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.

[0058] Preferred examples of photopolymerization initiators include acylphosphine oxide compounds; diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide are preferred, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide is more preferred. When an acylphosphine oxide compound is incorporated as a photopolymerization initiator, the curability of the ink composition of the present invention is further enhanced. The content of the photopolymerization initiator in the ink composition varies depending on the type of photopolymerization initiator, but is usually in the range of 3 to 20% by mass, preferably 5 to 12% by mass.

[0059] [1-5B. 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.

[0060] [1-5C. Polymerization Inhibitors] The ink composition of the present invention may contain a polymerization inhibitor. A polymerization inhibitor can suppress the occurrence of 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.

[0061] [1-5D. Pigment Dispersant] 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 pigment dispersants, basic group-containing acrylic pigment dispersants, basic group-containing urethane pigment dispersants, and basic group-containing carbodiimide pigment dispersants, as well as anionic surfactants.

[0062] 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 may contain 2 to 3,000 basic groups per molecule and may have a number-average molecular weight of 1,000 to 1,000,000.

[0063] The amount of pigment dispersant in the ink composition is preferably 1.0 to 200.0 parts by mass, based on a total pigment amount of 100 parts by mass.

[0064] [1-5E. Other Additives] Examples of other additives include solvents, ultraviolet absorbers, antioxidants, defoamers, preservatives, fungicides, rust inhibitors, thickeners, humectants, pH adjusters, and other various additives. The solvent is preferably present in the ink composition at 10.0% by mass or less, more preferably at 5.0% by mass or less, even more preferably at 2.0% by mass or less, and may not be present at all.

[0065] [2. Preparation of 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.

[0066] 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.

[0067] [3. Inkjet Printing of Ink Compositions] The ink composition of the present invention can be used for printing with an inkjet printing apparatus. The type of inkjet printing apparatus that can be used is not particularly limited and may be a line head type (single pass type) or a serial head type (multi-pass type). A continuous type inkjet printing apparatus may also be used, in which case a conductivity imparting agent can be added to adjust the conductivity of the ink composition.

[0068] 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 such that the thickness of the coating on the substrate is, for example, 1 to 60 μm.

[0069] The ink composition that lands on the substrate to be printed is exposed to and cured by active energy rays. 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 light-emitting diodes (LEDs) that generate ultraviolet light with an emission peak wavelength in the range of 350 to 420 nm as the light source.

[0070] 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.

[0071] 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, polyphenylsulfide polymers, polyvinyl alcohol polymers, polyvinylidene chloride polymers, polyvinyl butyral polymers, polyarylate polymers, polyoxymethylene polymers, and polyepoxy polymers, as well as blends of these polymers.

[0072] 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.

[0073] A. Preparation of Inkjet Printing Ink Compositions Inkjet printing ink compositions for each example and comparative example were prepared according to the composition formulations in Tables 1 to 3. The raw material components used in the preparation are shown below.

[0074] A-1. Photopolymerizable components <Amine-modified oligomers> ・CN371: Amine-modified oligomer (bifunctional) (Sartomer) <Monofunctional monomers> ・Isobornyl acrylate (glass transition temperature: 97°C) ・Benzyl acrylate (glass transition temperature: 6°C) ・Ethyl carbitol acrylate (glass transition temperature: -67°C) ・MEDOL-10: (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (glass transition temperature: -7°C) ・Acryloyl morpholine (glass transition temperature: 145°C) <Polyfunctional monomers> ・1,6-Hexanediol diacrylate (glass transition temperature: 43°C) ・Trimethylolpropane EO-modified triacrylate (glass transition temperature: 40°C)

[0075] A-2. Organic microparticles (melamine-based microparticles) (manufactured by Nippon Shokubai Co., Ltd.) ・Epostor® S6 (average particle size 0.4 μm) ・Epostor® SS (average particle size 0.1 μm) ・Epostor® S (average particle size 0.2 μm) ・Epostor® S12 (average particle size 1.2 μm)

[0076] A-3. Surface modifiers: BYK-315N: Polyester-modified polymethylalkylsiloxane; BYK-377: Polyether-modified hydroxyl group-containing polydimethylsiloxane

[0077] A-4. Photopolymerization initiators, sensitizers, and polymerization inhibitors: TPOL: Ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate; BAPO: Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide; DETX: Sensitizer (2,4-diethylthioxanthone); Igastab UV-22 (BASF): Polymerization inhibitor

[0078] A-5. Colorants (coloring pigments) • Phthalocyanine blue pigment PB15:4 • Quinacridone magenta pigment PR122 • Disazo yellow pigment PY155 • Carbon black PBk7

[0079] A-6. Pigment dispersants: Solspers SS32000 (Lubrisol Co., Ltd.), Adisper PB821 (Ajinomoto Fine Techno Co., Ltd.)

[0080] Using the components described above, inkjet printing ink compositions for each example and comparative example in Tables 1 to 3 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 3. 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. Separately, ink compositions without organic fine particles were prepared in the same manner for each example and comparative example inkjet printing ink composition and used for the evaluation of "B-8. Color Gamut" described later.

[0081] B. Evaluation of Ink Compositions and Cured Printed Materials The ink compositions prepared in each example and comparative example, and the printed materials (cured coatings of the printed materials) were evaluated based on the following points, and the evaluation results are shown in Tables 1 to 3.

[0082] B-1. Discharge Stability of Ink Compositions Each ink composition prepared in the examples and comparative examples was continuously printed (printed) on a substrate: polyvinyl chloride film (PVC80, manufactured by Lintec Corporation) using an inkjet recording device equipped with an inkjet nozzle, and the discharge stability was evaluated according to the following evaluation criteria. ○: Discharge is stable without any printing irregularities. △: Discharge is stable with some printing irregularities. ×: Discharge is present or stable discharge is not possible.

[0083] B-2. Curing of Ink Compositions 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 × 50 m / min, with an integrated UV light intensity of 75 mJ / cm². 2[UV integrated light intensity was determined by measuring the irradiation amount using an EIT UVIMAP (UM365H-S) as the measuring instrument, in the measurement ranges of 250-260 nm, 280-320 nm, 320-390 nm, and 395-445 nm.] This was considered one pass, and the coating film was irradiated with light to cure it. 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 rubbing marks remain on the coating film. △: After 6 passes, no uncured ink adheres to the cotton swab, and no rubbing marks remain on the coating film. ×: After 6 passes, uncured ink adheres to the cotton swab, or rubbing marks remain on the coating film.

[0084] B-3. ​​Abrasion Resistance of Printed Materials The cured coatings prepared using the ink compositions in the examples and comparative examples were printed onto PVC boards (T938, manufactured by Takiron CI Co., Ltd.) and then rubbed with a bleaching cloth at 500g x 100 times at 60 rpm using a Gakushin-type friction fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.). The degree to which the coating was removed was visually observed and evaluated according to the following criteria: ○: No removal of the coating. △: Scratches on the surface of the coating. ×: Clear removal of the coating.

[0085] B-4. Solvent 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.). The cured coating film was then rubbed with an ethanol-soaked bleaching cloth 200g x 10 times at 30 rpm using a Gakushin-type friction fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.). The degree to which the coating film was removed was visually observed and evaluated according to the following criteria: ○: No removal of coating film. △: Scratches on the surface of the coating film. ×: Clear removal of coating film is observed.

[0086] B-5. Slipperiness of Printed Materials Each ink composition prepared in the examples and comparative examples was printed onto a PET film. The ink-coated surface of each evaluation piece of the cured coating film was then placed on top of the PET film and left to stand for 10 seconds. After that, the pieces were slid at a sliding speed of 500 mm / min, and the static friction coefficient was measured in accordance with JIS-K7125 and evaluated according to the following criteria: ○: Measured static friction coefficient in the range of 0.1 to 0.5. △: Measured static friction coefficient greater than 0.5 to 1.0. ×: Measured static friction coefficient greater than 1.0.

[0087] B-6. Blocking resistance of printed materials. Cured coatings obtained by printing each ink composition prepared in the examples and comparative examples onto PET film were measured on a 4 x 5 cm sheet. ２ The film was cut to size, the ink side of the hardened coating was placed on top of the PET film, and a 2kg load was applied. The adhesion of the coating after one day was checked. ○: There are no adhesion marks on the coating and it can be peeled off without resistance. △: There are slight adhesion marks on the coating, or there is resistance to peeling when removed. ×: There are adhesion marks on the coating, and the ink peels off when removed.

[0088] B-7. Stretchability of Printed Materials Each ink composition prepared in the examples and comparative examples was applied to a substrate: polyvinyl chloride film (PVC80, manufactured by Lintec Corporation) using a bar coater No. 6. Then, using a conveyor-type light irradiation device (Heraeus STM-250E-16, lamp: Z-8 lamp (metal halide type)), the light was irradiated at 120W × 50 m / min, with an integrated UV light intensity of 75 mJ / cm². 2 [UV integrated light intensity was determined by measuring the irradiation amount using an EIT UVIMAP (UM365H-S) as the measuring instrument, in the measurement ranges of 250-260 nm, 280-320 nm, 320-390 nm, and 395-445 nm.] The coating film was rubbed with a cotton swab and cured until no uncured ink adhered to the cotton swab, creating a cured coating film. The obtained printed material was cut into 2 cm x 5 cm pieces, and the cracking of the coating film when uniaxially stretched was visually observed and evaluated according to the following criteria: ○: No cracking of the coating film occurs even when stretched by 40%. △: Cracking of the coating film occurs when stretched by 20% to 40%. ×: Cracking of the coating film occurs when stretched by less than 20%.

[0089] B-8. Each ink composition obtained in the color gamut examples and comparative examples, along with ink compositions without organic fine particles, were printed at 100% solid color onto a substrate: polyvinyl chloride film (PVC80, manufactured by Lintec Corporation) using an inkjet recording device equipped with an inkjet nozzle to obtain printed materials. 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 of 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 the corresponding ink composition without organic fine particles, and the color gamut was evaluated under the following conditions: ○: ΔE ≤ 5 △: 5 < ΔE ≤ 10 ×: 10 < ΔE

[0090]

[0091]

[0092]

[0093] As shown in Comparative Example 1 of Table 3, ink compositions with a low content of organic fine particles (0.5% by mass relative to the ink composition) exhibited poor lubricity of the cured coating film and blockage; furthermore, the cured coating film also lacked sufficient abrasion resistance and solvent resistance.

[0094] On the other hand, as shown in Comparative Example 2 of Table 3, ink compositions with a high content of organic fine particles (12% by mass relative to the ink composition; a ratio of 3.0 to the colorant) showed deterioration in both discharge stability and color gamut evaluation. Similarly, the ink composition of Comparative Example 4 of Table 3 (organic fine particle content ratio to colorant of 2.0) and the ink composition of Comparative Example 5 of Table 3 (10% by mass relative to the ink composition; organic fine particle content ratio to colorant of 1.7) showed deterioration in both discharge stability and color gamut evaluation. In contrast, as shown in the examples in Tables 1 to 3, ink compositions containing an appropriate amount of organic fine particles performed well in all evaluation items.

[0095] As shown in Comparative Example 3 of Table 3, ink compositions with large organic microparticle sizes (epostor S12: average particle diameter of 1.2 μm) exhibited poor discharge stability. In contrast, as shown in the examples in Tables 1 to 3, reducing the average particle diameter of the organic microparticles to 0.8 μm or less improved the discharge stability of the ink composition and yielded better results in other evaluations.

[0096] As shown in Comparative Example 6 of Table 3, the ink composition that did not contain the amine-modified oligomer showed reduced curability, deterioration of the abrasion resistance and solvent resistance of the cured coating film, and blockage of the printed material.

[0097] The ink compositions of Examples 1 to 21 in Tables 1 to 3 received evaluations of sufficient practical use in all evaluation items. As can be seen from the comparison of Examples 1 to 4 in Table 1, it can be seen that the color gamut evaluation is sufficient when the relative ratio of organic fine particles to colorant is within a certain range, but as the content ratio of organic fine particles increases, there was a tendency for the color gamut evaluation to decrease. In addition, as the content of organic fine particles decreases, there was a tendency for the blocking resistance of the cured coating film to decrease.

[0098] As can be seen from the comparison between Example 1 and Example 5, sufficient evaluation results are obtained in all items regardless of the type of surface modifier. Furthermore, as can be seen from the comparison between Examples 1, 6, and 7, sufficient evaluation results are obtained in all items even when the type of photopolymerization initiator is changed or the composition of the polyfunctional monomer is changed (even when using polyfunctional monomers with three or more functions). As can be seen from the comparison between Examples 1, 8, and 9, sufficient evaluation results are obtained in all items even when the particle size of the organic fine particles is changed within a predetermined range.

[0099] As can be seen from the comparison between Example 1 and Example 10, even when the photopolymerization initiator is changed, sufficient evaluation results are obtained in all items. As can be seen from the comparison between Examples 1, 11, 12, and 13, sufficient evaluation results are obtained in all items regardless of the type of pigment. As can be seen from the comparison between Examples 14 to 16, the content of amine-modified oligomer can be adjusted, but when the content of amine-modified oligomer is low, there is a tendency for curability to decrease and the abrasion resistance of the cured coating film to decrease.

[0100] As shown in Example 17, an increase in polyfunctional monomers in the polymerizable component tends to decrease the stretchability of the cured coating film. As shown in Examples 18 to 21, even when the composition of monofunctional monomers in the polymerizable component is adjusted in various ways, sufficient evaluation results are obtained for all items.

[0101] The ink composition of the present invention, as an active energy ray curable inkjet printing ink, ensures all 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, because it offers high color reproduction of printed materials, it can be applied to a variety of inkjet printing applications. 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 polymerizable component containing a monofunctional monomer and an amine-modified oligomer, organic fine particles, and a surface modifier, wherein the organic fine particles are organic fine particles with an average particle diameter of 0.1 to 0.8 μm; the content of the organic fine particles is 1.2 to 8% by mass relative to the active energy ray-curable inkjet printing ink composition; and the content ratio of the organic fine particles to the colorant component (organic fine particles / colorant component) is 1.5 or less.

2. The active energy ray curable inkjet printing ink composition according to claim 1, wherein the average particle size of the organic fine particles is 0.5 μm or less.

3. 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 the molecule.

4. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the content of the amine-modified oligomer is 0.5 to 20% by mass relative to the total amount of the polymerizable components.

5. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the content of the monofunctional monomer is 60% by mass or more relative to the total amount of the polymerizable components.

6. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the polymerizable component contains a polyfunctional monomer, and the content of the polyfunctional monomer is 2 to 40% by mass relative to the total amount of the polymerizable component.

7. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the organic fine particles are fine particles of a cross-linked polymer.

8. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the organic fine particles are melamine-based fine particles.

9. The active energy ray curable inkjet printing ink composition according to claim 1 or 2, wherein the surface modifier is a silicone-based surface modifier.

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

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