Active energy ray-curable ink, method for producing the same, and printed matter

Abstract

To provide an active energy ray-curable ink having excellent printability and improved resolution and curability, as well as printed matter produced therewith.SOLUTION: An active energy ray-curable ink comprises a urethane (meth)acrylate (A) and a resin (C) having a cyclic structure, where the (meth)acryloyl group concentration of the urethane (meth)acrylate (A) is in the range of 4.0 to 8.0 mmol / g.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel and useful active energy ray-curable ink, a method for producing the same, and a printed matter.

Background Art

[0002] In recent years, due to the increasing demand for shorter delivery times and environmental friendliness in printing, the use of active energy ray-curable inks, which are quick-drying and do not use solvents, has been expanding, replacing the conventionally used oil-based inks. Active energy ray-curable inks contain an unsaturated compound having active energy ray-curability, such as an acrylic ester compound, as a constituent component, and instantaneously cure upon irradiation with active energy rays, forming a tough film by three-dimensional crosslinking of the above unsaturated compound. Since it cures instantaneously, post-processing can be performed immediately after printing. Therefore, active energy ray-curable inks are preferably used in packaging printing and foam printing in the commercial field, etc., where a strong film is required for productivity improvement and design protection.

[0003] For active energy ray-curable inks, binder resins typified by diallyl phthalate resin are often used for the purpose of imparting printability. However, since most binder resins do not have (meth)acryloyl groups, they do not participate in three-dimensional crosslinking formation in the cured film of the active energy ray-curable ink, resulting in the problem of deteriorating the curability of the ink. On the other hand, the use of urethane acrylate, which is a binder resin having a (meth)acryloyl group, can solve the problem of the curability of the ink. For example, Patent Document 1 discloses an ink using urethane acrylate having a (meth)acryloyl group concentration in the range of 1.5 to 3.9 mmol / g, with hydroxyethyl acrylate, polyol, and polymeric MDI as raw materials. Patent Document 2 discloses an ink using urethane acrylate prepared from pentaerythritol triacrylate, polypropylene glycol with a molecular weight of 1000, and isophorone diisocyanate as raw materials. However, the (meth)acryloyl group concentration of the urethane acrylate in Patent Document 2 only reaches about 1.6 mmol / g. In the printing field, further improvement in productivity and reduction in the irradiation amount of active energy rays are required. Therefore, improvement in the curability of the ink by further introducing (meth)acryloyl groups into urethane acrylate is required.

[0004] In addition, compared with oil-based inks, active energy ray-curable inks are prone to problems such as ink mist generated by the rotation of rollers in the printing press, which causes the printing press to become dirty, and problems such as ink not being scraped from the ink pot to the rollers during printing (ink pot escape) due to poor fluidity of the ink. In recent years, the market has demanded the provision of more high-definition and clear printed matter. Patent Document 3 discloses an active energy ray-curable coating composition comprising a urethane urea (meth)acrylate oligomer and a photopolymerization initiator, but it is insufficient for suppressing troubles on the printing press and providing high-definition printed matter described above.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 International Publication No. 2016 / 63625 Patent Document 2 Japanese Patent Application Laid-Open No. 60-161468 Patent Document 3 Japanese Patent Application Laid-Open No. 2006-249353 Summary of the Invention Problems to be Solved by the Invention

[0006] An object of the present invention is to provide an active energy ray-curable ink having good printability, high definition, and improved curability, and a printed matter thereof. Means for Solving the Problems

[0007] The inventors of the present invention have found that an active energy ray-curable ink containing a urethane acrylate having a (meth)acryloyl group concentration in the range of 4.0 to 8.0 mmol / g and a resin having a ring structure eliminates ink mist and potting problems during printing, and provides an ink capable of providing excellent curability and a high-definition printed matter, thus arriving at the present invention.

[0008] That is, the present invention is an active energy ray-curable ink containing a urethane (meth)acrylate (A) and a resin (C) having a ring structure, and relates to an active energy ray-curable ink characterized in that the (meth)acryloyl group concentration of the urethane (meth)acrylate (A) is in the range of 4.0 to 8.0 mmol / g.

[0009] Further, the present invention relates to the above-mentioned active energy ray-curable ink, characterized in that the urethane (meth)acrylate (A) is a reaction product of a (meth)acrylic compound (a1) having one or more hydroxyl groups, a polyol compound (a2) other than (a1), and an isocyanate compound (a3).

[0010] Furthermore, the present invention relates to the above-mentioned active energy ray-curable ink, wherein the resin (C) having a ring structure has a weight average molecular weight of 1,000 to 100,000.

[0011] Furthermore, the present invention relates to the above-mentioned active energy ray-curable ink, wherein the resin (C) having a ring structure contains one or more selected from the group consisting of allyl resins, diallyl phthalate resins, rosins, maleated rosins, acrylated rosins, rosin-modified resins, epoxy resins, polyester resins, polyurethane resins, alkyd resins, and petroleum resins.

[0012] Furthermore, the present invention relates to the above-mentioned active energy ray-curable ink, which further contains a (meth)acrylic compound (excluding the cases where it is (A) and (C)).

[0013] Furthermore, the present invention relates to the above-mentioned active energy ray-curable ink, wherein the hydroxyl value of the polyol compound (a2) is 125 to 1850 mgKOH / g.

[0014] Furthermore, the present invention relates to the above-mentioned active energy ray-curable ink, wherein the ratio [(a1') / (a3')] of the number of moles (a1') of the hydroxyl group contained in the (meth)acrylic compound (a1) having one or more hydroxyl groups to the number of moles (a3') of the isocyanate group contained in the isocyanate compound (a3) is in the range of 0.2 to 0.6.

[0015] Furthermore, the present invention relates to a method for producing the above-mentioned active energy ray-curable ink, which includes a step of reacting a (meth)acrylic compound (a1) having one or more hydroxyl groups, a polyol compound (a2) other than (a1), and an isocyanate compound (a3) in a (meth)acrylic compound (excluding the cases where it is (A) and (C)) to obtain a urethane (meth)acrylate (A).

[0016] The present invention also relates to a printed matter having a cured product of the above-mentioned active energy ray-curable ink on a substrate. Effect of the Invention

[0017] INDUSTRIAL APPLICABILITY The present invention provides an actinic ray-curable ink having printability, high-definition printed matter and excellent curability, and a printed matter thereof, which is extremely useful industrially. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiment described below, and various modifications are possible without departing from the spirit of the present invention.

[0019] The active energy ray curable ink of the present invention contains a urethane (meth)acrylate (A) and a resin (C) having a ring structure, and is characterized in that the (meth)acryloyl group concentration of the urethane (meth)acrylate (A) is in the range of 4.0 to 8.0 mmol / g. When the (meth)acryloyl group concentration of the urethane (meth)acrylate (A) is in the range of 4.0 to 8.0 mmol / g, it is possible to achieve both excellent printability and curability. When the (meth)acryloyl group concentration is less than 4.0 mmol / g, the curability of the ink deteriorates, and when it is 8.0 or more, it becomes difficult to introduce a structure that exhibits printability. The (meth)acryloyl group concentration of the urethane (meth)acrylate (A) is preferably in the range of 4.5 to 7.5 mmol / g, more preferably in the range of 5.0 to 7.0 mmol / g.

[0020] The content of the urethane (meth)acrylate (A) used in the present invention is preferably from 5 to 40 mass %, and more preferably from 7 to 30 mass %, based on the total amount of the ink, from the viewpoints of printability and curability.

[0021] As a preferred form of the urethane (meth)acrylate (A) of the present invention, a reaction product of a (meth)acrylic compound (a1) having one or more hydroxyl groups, a polyol compound (a2) other than (a1), and an isocyanate compound (a3) can be mentioned.

[0022] ((meth)acrylic compound (a1) having one or more hydroxyl groups) Examples of the (meth)acrylic compound (a1) having one or more hydroxyl groups include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, polyethylene glycol (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylates, glycerin poly(meth)acrylate, diglycerin poly(meth)acrylate, trimethylolpropane poly(meth)acrylate, ditrimethylolpropane poly(meth)acrylate, pentaerythritol poly(meth)acrylate, dipentaerythritol poly(meth)acrylate, polypentaerythritol poly(meth)acrylate, and the like. These (meth)acrylic compounds (a1) having one or more hydroxyl groups may be used alone or in combination of two or more. Among these, from the viewpoint of making the (meth)acryloyl group concentration of the urethane (meth)acrylate (A) 4.0 to 8.0 mmol / g, it is preferable to use pentaerythritol polyacrylate, dipentaerythritol polyacrylate, or polypentaerythritol polyacrylate. Further, from the viewpoint of ink fluidity, it is preferable to use dipentaerythritol polyacrylate.

[0023] (Polyol compound (a2) other than (a1)) As the polyol compound (a2) other than (a1), a polyol compound having two or more hydroxyl groups in the molecule can be used. Preferably, as the polyol compound (a2), at least one selected from the group consisting of a polyol compound having 2 to 20 carbon atoms, an alkylene oxide-modified product of a polyol compound having 2 to 20 carbon atoms, and an amine compound is used, and the storage stability of the resin composition is improved by using these. More preferably, as the polyol compound (a2), a polyol compound having a hydroxyl value in the range of 50 to 1850 mgKOH / g is used, and the curability is improved by using these.

[0024] Examples of polyol compounds having 2 to 20 carbon atoms include linear alkylene dihydric alcohols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,2-octanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol, 1,12-dodecanediol, 1,2-dodecanediol, 1,14-tetradecanediol, 1,2-tetradecanediol, 1,16-hexadecanediol, 1,2-hexadecanediol, 1,18-octadecanediol, 1,2-octadecanediol, 1,20-eicosanediol, 1,2-eicosanediol; branched alkylene dihydric alcohols such as neopentyl glycol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-dimethylpentanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, dimethylol octane, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol; and cyclic alkylene dihydric alcohols such as 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cycloheptanediol, tricyclodecanedimethanol, bisphenol A, bisphenol F, bisphenol S, hydrogenated bisphenol A, hydrogenated bisphenol, hydrogenated bisphenol S. In addition, examples of polyhydric alcohols having a valency of 3 or higher include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, diglycerin, ditrimethylolpropane, dipentaerythritol, tripentaerythritol, sorbitan, sorbitol, inositol, and the like. These polyol compounds having 2 to 20 carbon atoms may be used alone or in combination of two or more. Among these, from the viewpoint of easy availability, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, glycerin, trimetholpropane, pentaerythritol, etc. are preferably used.

[0025] Examples of the alkylene oxide-modified products of the polyol compounds having 2 to 20 carbon atoms include compounds obtained by subjecting the above polyol compounds having 3 to 20 carbon atoms to alkylene oxide modification such as ethylene oxide modification (EO modification), propylene oxide modification (PO modification), and butylene oxide modification (BO modification). The alkylene oxide-modified products of the polyol compounds having 2 to 20 carbon atoms may be used alone or in combination of two or more. Examples of the alkylene oxide-modified products of the polyol compounds having 2 to 20 carbon atoms include PEG series (manufactured by Sanyo Chemical Industries, Ltd., polyethylene glycol), Sunix PP series (manufactured by Sanyo Chemical Industries, Ltd., polypropylene glycol), PTMG series (manufactured by Mitsubishi Chemical Corporation, polytetramethylene glycol), Unionox G series (manufactured by NOF Corporation, ethylene oxide-modified glycerin), Sunix GP series (manufactured by Sanyo Chemical Industries, Ltd., propylene oxide-modified glycerin), Sunix TP series (manufactured by Sanyo Chemical Industries, Ltd., propylene oxide-modified trimetholpropane), Wilbride S-753D (manufactured by NOF Corporation, EOPOBO-modified glycerin), and the like.

[0026] Examples of the amine compound include amine compounds having two substituents with a hydroxyl group and one substituent without a hydroxyl group, such as N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine, N-tert-butyldiethanolamine, N-methyldipropanolamine, N-ethyldipropanolamine, N-butyldipropanolamine, N-tert-butyldipropanolamine, N-methyldibutanolamine, N-ethyldibutanolamine, N-butyldibutanolamine, N-tert-butyldibutanolamine, N-pentyldibutanolamine, Examples of the amine compound include amine compounds having three substituents with a hydroxyl group, such as trimethanolamine, triethanolamine, and tributanolamine.

[0027] Among these amine compounds, it is preferable to use an amine compound that is a tertiary amine because it can suppress an unintended cross-linking reaction by preventing reactions such as the reaction between an amino group and an isocyanate group and the Michael addition reaction between an amino group and an acryloyl group.

[0028] The polyol compound (a2) may be used alone or in combination of two or more.

[0029] From the balance between storage stability and curability, the content of the amine compound in the polyol compound (a2) is preferably 5 to 80 mol%, more preferably 10 to 50 mol%, based on the total number of moles of the polyol compound (a2).

[0030] (Isocyanate compound (a3)) Examples of the isocyanate compound (a3) include tolylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, dimer diisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group, Millionate MR400 (manufactured by Tosoh Corporation, polymeric MDI), and the like. Among these, a diisocyanate compound is preferable from the viewpoint of reaction control.

[0031] (Method for producing urethane (meth)acrylate (A)) A method for producing a reaction product of a (meth)acrylic compound (a1) having one or more hydroxyl groups, a polyol compound (a2) other than (a1), and an isocyanate compound (a3) will be described. The reaction of the (meth)acrylic compound (a1) having one or more carboxyl groups, the polyol compound (a2) other than (a1), and the isocyanate compound (a3) may be carried out simultaneously, or after previously reacting the (meth)acrylic compound (a1) having one or more carboxyl groups and the isocyanate compound (a3), the polyol compound (a2) may be reacted. Since the (meth)acrylic compound (a1) having one or more carboxyl groups can be surely reacted with the polyol compound (a2) via the isocyanate compound (a3), it is more preferable to react the polyol compound (a2) after previously reacting the (meth)acrylic compound (a1) having one or more carboxyl groups and the isocyanate compound (a3). The ratio [(a1') / (a3')] of the number of moles of carboxyl groups (a1') contained in the (meth)acrylic compound (a1) having one or more carboxyl groups to the number of moles of isocyanate groups (a3') contained in the isocyanate compound (a3) is preferably in the range of 0.2 to 0.6. When [(a1') / (a3')] is in the range of 0.2 to 0.6, the molecular weight of the urethane (meth)acrylate (A) is suitable and the printing suitability is improved.

[0032] The reaction proceeds even without a catalyst, but a catalyst can also be used. Examples of the catalyst that can be used include tertiary amine-based catalysts such as triethylamine and dimethylaniline, and metal-based catalysts such as tin and zinc. From the viewpoint of reactivity, tin 2-ethylhexanoate is preferable. The reaction can be carried out in a solvent if necessary, but it can also be carried out in the (meth)acrylic compound described below. Since the steps of dissolving the urethane (meth)acrylate (A) in the (meth)acrylic compound and removing the solvent can be omitted, it is preferable.

[0033] From the viewpoint of printing suitability, the molecular weight of the urethane (meth)acrylate (A) is preferably in the range of 2000 to 30000 as the weight average molecular weight. In the present invention, the weight average molecular weight was measured by gel permeation chromatography (HLC-8320) manufactured by Tosoh Corporation. The calibration curve was created using standard polystyrene samples. The eluent was tetrahydrofuran, and three TSKgel SuperHM-M (manufactured by Tosoh Corporation) columns were used. The measurement was performed at a flow rate of 0.6 ml / min, an injection volume of 10 μl, and a column temperature of 40°C.

[0034] In addition, the number of (meth)acryloyl groups contained in the urethane (meth)acrylate (A) is preferably 4 to 50 per molecule, more preferably 7 to 30 per molecule, from the viewpoints of printability and curability.

[0035] (Resin (C) having a cyclic structure) In the present invention, the resin (C) having a cyclic structure is not particularly limited as long as it is a compound having one or more structural units having a cyclic structure in one molecule of the resin. Examples of the cyclic structure include a cyclic hydrocarbon compound skeleton and a heterocyclic compound skeleton, which may have a substituent. The proportion of the structural unit having a cyclic structure in one molecule of the resin is preferably 10 to 90% by mass, with 100% by mass of one molecule of the resin, from the viewpoints of providing a clear printed matter and printability.

[0036] The cyclic hydrocarbon compound may be any of alicyclic hydrocarbon compounds such as cycloalkanes, cycloalkenes, cycloalkynes, and aromatic hydrocarbon compounds, and may have substituents. The skeleton forming the cyclic hydrocarbon compound is not particularly limited, but aromatic monobasic acids such as benzoic acid, methylbenzoic acid, tertiary butylbenzoic acid, naphthoic acid, orthobenzoylbenzoic acid, resin acids such as abietic acid, neoabietic acid, palustric acid, dehydroabietic acid, pimaric acid, isopimaric acid, sandaracopimaric acid, communic acid, 1,2,3,6-tetrahydrophthalic acid, 3-methyl-1,2,3,6-tetrahydrophthalic acid, 4-methyl-1,2,3,6-tetrahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, o-phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, dihydroagatolic acid and their acid anhydrides, benzene, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclobutyne, cyclopentyne, cyclohexyne are mentioned. Furthermore, alcohols such as phenol, cresol, tertiary butylphenol, octylphenol, naphthol, cyclohexanedimethanol, cyclohexanediethanol, benzyl alcohol and the like can be mentioned.

[0037] The heterocyclic compound is a compound having a cyclic structure composed of carbon atoms and at least one or more non-carbon atoms, and the non-carbon atoms are called heteroatoms. The type of heteroatom is not particularly limited, but nitrogen atoms, oxygen atoms, silicon atoms, and sulfur atoms are preferred.

[0038] The skeleton forming the heterocyclic compound is not particularly limited, but isoxazole, isothiazole, imidazole, oxazole, silole, selenophene, thiadiazole, tetrazole, tetrahydrofuran, triazole, pyrrolidine, pyrrole, furan, dioxane, thiazine, tetrazine, piperidine, pyridine, pyran, morpholine, pyrimidine, thiophene and the like can be mentioned.

[0039] The resin (C) having a cyclic structure is not particularly limited as long as it is a compound having one or more structural units having a cyclic structure in one resin molecule, and examples thereof include allyl resins, diallyl phthalate resins, rosins, maleated rosins, acrylated rosins, rosin-modified resins, polychlorinated biphenyls, poly(meth)acrylic acid esters, epoxy resins, polyester resins, polyurethane resins, cellulose derivatives (for example, ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride-vinyl acetate copolymers, polyamide resins, polyvinyl acetal resins, alkyd resins, petroleum resins, urea resins, and the like. Among these, from the viewpoint of providing a clear printed matter, it is preferable to use one or more selected from the group consisting of allyl resins, diallyl phthalate resins, rosins, maleated rosins, acrylated rosins, rosin-modified resins, epoxy resins, polyester resins, polyurethane resins, alkyd resins, and petroleum resins, and more preferably to use one or more selected from the group consisting of allyl resins, diallyl phthalate resins, rosin-modified resins, polyester resins, and petroleum resins.

[0040] The molecular weight of the resin (C) having a cyclic structure is preferably 1,000 to 100,000, more preferably 2,000 to 60,000 in terms of weight average molecular weight. By setting the weight average molecular weight to 1,000 or more, the clarity of the printed surface is improved, and by setting it to 100,000 or less, the compatibility with urethane (meth)acrylate is improved.

[0041] The content of the resin (C) having a cyclic structure is preferably 2 to 30% by mass, more preferably 4 to 25% by mass, based on the total amount of the ink, from the viewpoint of the clarity of the printed surface.

[0042] In the active energy ray-curable ink of the present invention, the total content of the urethane (meth)acrylate (A) and the resin (C) having a cyclic structure is preferably 5 to 40% by mass, more preferably 7 to 30% by mass.

[0043] ((Meth)acrylic compounds (except for cases (A) and (C))) The content of the (meth)acrylic compound used in the ink of the present invention is 10 to 90% by mass, more preferably 20 to 85% by mass, and even more preferably 30 to 80% by mass based on the total amount of the ink.

[0044] The (meth)acrylic compound is not particularly limited, and examples include monofunctional (meth)acrylic compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, acryloylmorpholine, etc.; difunctional (meth)acrylic compounds such as ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate (n = 2 to 20), propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate (n = 2 to 20), alkane (carbon number 4 to 12) glycol di(meth)acrylate, alkane (carbon number 4 to 12) glycol ethylene oxide adduct (2 to 20 moles) di(meth)acrylate, alkane (carbon number 4 to 12) glycol propylene oxide adduct (2 to 20 moles) di(meth)acrylate, hydroxypivalyl hydroxypivalate di(meth)acrylate, tricyclodecane dimethylol di(meth)acrylate, bisphenol A ethylene oxide adduct (2 to 20 moles) di(meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol A ethylene oxide adduct (2 to 20 moles) di(meth)acrylate, etc. Trifunctional (meth)acrylic compounds such as glycerol tri(meth)acrylate, glycerol ethylene oxide adduct (3 to 30 moles) tri(meth)acrylate, glycerol propylene oxide adduct (3 to 30 moles) tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethylene oxide adduct (3 to 30 moles) tri(meth)acrylate, trimethylolpropane propylene oxide adduct (3 to 30 moles) tri(meth)acrylate, Tetrafunctional or higher (meth)acrylic compounds such as pentaerythritol tetra(meth)acrylate, pentaerythritol ethylene oxide adduct (4 to 40 moles) tetra(meth)acrylate, pentaerythritol propylene oxide adduct (4 to 40 moles) tetra(meth)acrylate, diglycerol tetra(meth)acrylate, pentaerythritol ethylene oxide adduct (4 to 40 moles) tetra(meth)acrylate, pentaerythritol propylene oxide adduct (4 to 40 moles) tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ditrimethylolpropane ethylene oxide adduct (4 to 40 moles) tetra(meth)acrylate, ditrimethylolpropane propylene oxide adduct (3 to 30 moles) tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol ethylene oxide adduct (6 to 60 moles) hexa(meth)acrylate, dipentaerythritol propylene oxide adduct (6 to 60 moles) hexa(meth)acrylate, (Meth)acrylate compounds such as polyester (meth)acrylate, urethane (meth)acrylate other than (A), epoxy (meth)acrylate, and mixtures thereof. Among these, it is preferable to use a bifunctional or higher (meth)acrylic compound from the viewpoint of curability. Also, the proportion of the bifunctional or higher (meth)acrylic compound in the total amount of the (meth)acrylic compound is preferably 40 to 100% by mass from the viewpoint of curability.

[0045] The active energy ray-curable ink of the present invention can use an active energy ray-curable compound other than a (meth)acrylic compound according to the required physical properties of the cured film.

[0046] As the active energy ray-curable compound other than the (meth)acrylic compound, a vinyl compound can be used, and examples thereof include styrene, N-vinylpyrrolidone, divinylbenzene, and the like.

[0047] The active energy ray-curable ink of the present invention can add a pigment as a colorant. When the pigment is not contained, it becomes a clear ink (hereinafter also referred to as "varnish"), and when the pigment is contained, it becomes a colored ink.

[0048] Examples of the pigment can include inorganic pigments and organic pigments. Examples of the inorganic pigments include lead yellow, zinc yellow, ultramarine blue, barium sulfate, cadmium red, titanium oxide, zinc white, Indian red, alumina white, calcium carbonate, ultramarine, carbon black, graphite, aluminum powder, red iron oxide, etc. Examples of the organic pigments include soluble azo pigments such as β-naphthol-based, β-oxynaphthoic acid-based, β-oxynaphthoic acid anilide-based, acetoacetic acid anilide-based, pyrazolone-based, etc., insoluble azo pigments such as β-naphthol-based, β-oxynaphthoic acid anilide-based, acetoacetic acid anilide-based monoazo, acetoacetic acid anilide-based disazo, pyrazolone-based, etc., phthalocyanine-based pigments such as copper phthalocyanine blue, halogenated (chlorinated or brominated) copper phthalocyanine blue, sulfonated copper phthalocyanine blue, metal-free phthalocyanine, etc., polycyclic pigments and heterocyclic pigments such as quinacridone-based, dioxazine-based, threne-based (such as pyranthrone, anthraanthrone, indanthrone, anthrapyrimidine, flavanthrone, thioindigo-based, anthraquinone-based, perinone-based, perylene-based, etc.), isoindolinone-based, metal complex-based, quinophthalone-based, etc., and various known and publicly used pigments can be used.

[0049] A resin can be used in the active energy ray-curable ink of the present invention as needed. The resins that can be used in the present invention are not particularly limited, and examples include diallyl orthophthalate resin, diallyl isophthalate resin, diallyl terephthalate resin, polyester resin, polyvinyl chloride, poly(meth)acrylate ester, epoxy resin, polyurethane resin, petroleum (based) resin, cellulose derivatives (for example, ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride-vinyl acetate copolymer, polyamide resin, polyvinyl acetal resin, polyamide resin, polyvinyl acetal resin, butadiene-acrylonitrile copolymer, and the like. These resins can be used alone or in combination of two or more.

[0050] In the active energy ray-curable ink of the present invention, a photoinitiator can be used as needed. Specifically, when ultraviolet rays are used as the active energy ray, it is necessary to add a photoinitiator. Examples of the photoinitiator include photo-cleavage type initiators and hydrogen abstraction type polymerization initiators. On the other hand, when electron beams or the like are used as the active energy ray, a photoinitiator is not required.

[0051] Examples of the photo-cleavage type initiator include α-(dimethyl)aminoalkylphenone compounds and α-morpholinoalkylphenone compounds.

[0052] More specifically, examples of the α-(dimethyl)aminoalkylphenone compound include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 or 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, and examples of the α-morpholinoalkylphenone compound include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one. These can be used alone or in combination of two or more.

[0053] Furthermore, examples of the hydrogen abstraction type polymerization initiator include dialkylbenzophenone compounds and thioxanthone compounds.

[0054] More specifically, examples of the dialkylaminobenzophenone compound include 4,4'-dialkylaminobenzophenones such as 4,4'-bis-(dimethylamino)benzophenone and 4,4'-bis-(diethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide. The dialkylaminobenzophenone compound may be used alone or in combination of two or more. Examples of the thioxanthone compound include 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dichlorothioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthon-2-yloxy)-N,N,N-trimethyl-1-propanamine hydrochloride. These may be used alone or in combination of two or more.

[0055] When ultraviolet rays are used as the active energy ray, the compounding amount of the photopolymerization initiator is preferably 0.01 to 20% by mass, more preferably 0.05 to 15% by mass, based on the total amount of the ink.

[0056] In addition, a sensitizer can be used in the active energy ray-curable ink of the present invention as needed. Examples of the sensitizer include benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 2,3,4-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, methyl-o-benzoylbenzoate, [(4-(methylphenylthio)phenyl]phenylmethanone, (4-benzoylbenzyl)trimethylammonium chloride, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxy-cyclohexyl-phenylketone, 2-hydroxy-2-methyl-1-styrylpropan-1-one polymer, diethoxyacetophenone, dibutoxyacetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin normal butyl ether, and the like. These may be used alone or in combination of two or more.

[0057] Other additives can be used in the active energy ray-curable ink of the present invention as needed.

[0058] As an additive for imparting storage stability to the ink, a radical polymerization inhibitor can be added. Examples of the radical polymerization inhibitor include (alkyl)phenol, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-diphenyl-2-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-tert-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cupferron, aluminum N-nitrosophenylhydroxylamine, triphenylmethyl, N-(3-oxyaniolino-1,3-dimethylbutylidene)aniline oxide, dibutyl cresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime, cyclohexanone oxime, and the like. When using a polymerization inhibitor, its content is preferably in the range of 0.01 to 1% by mass based on the total mass of the composition.

[0059] In addition, wax can be added as an additive for imparting abrasion resistance, antiblocking property, slipperiness, and anti-squeezing property. Examples of the wax include natural waxes such as carnauba wax, wood rosin, lanolin, montan wax, paraffin wax, and microcrystalline wax, and synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax, and silicone compounds.

[0060] In addition, additives such as an ultraviolet absorber, an infrared absorber, and an antibacterial agent can be added according to the required performance.

[0061] The active energy ray-curable ink of the present invention is adjusted to a composition consisting of 0 to 30% by mass of a pigment, 5 to 40% by mass of urethane (meth)acrylate (A), 10 to 90% by mass of a (meth)acrylic compound, 2 to 30% by mass of a resin (C) having a ring structure, 0 to 20% by mass of a photopolymerization initiator and / or a sensitizer, and 0 to 10% by mass of other additives with respect to the whole ink.

[0062] The method for producing the active energy ray-curable ink of the present invention may be carried out by the same method as the conventional active energy ray-curable ink. For example, between room temperature and 100 °C, the above pigment, urethane (meth) acrylate (A), (meth) acrylic compound, resin (C) having a ring structure, polymerization inhibitor, photoinitiator and sensitizer, and other additive components of the ink composition are produced using a kneading, mixing, and adjusting machine such as a kneader, three-roll mill, attritor, sand mill, gate mixer, etc.

[0063] As a method for printing or coating the ink of the present invention on a substrate, there are a roll coater, gravure coater, flexo coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, transfer roll coater, kiss coater, curtain coater, cast coater, spray coater, die coater, offset printing (ordinary lithography using dampening water and waterless lithography without using dampening water), flexo printing, gravure printing, screen printing, etc.

[0064] <Laminate> The laminate in the present invention is obtained by printing or coating the ink of the present invention on a substrate and curing it with active energy rays. The substrate is not particularly limited, and known ones can be used. Specifically, coated papers such as art paper, coated paper, and cast paper, uncoated papers such as high-quality paper, medium-quality paper, and newsprint, synthetic papers such as Yupo paper, plastic films such as PET (polyethylene terephthalate), PP (polypropylene), and OPP (biaxially stretched polypropylene), metal plates such as steel, copper, stainless steel, stainless steel, aluminum, tin-plated steel sheet, and tin-free steel, or metal underfloor plates provided with a base coat (primer) layer on these metal plates, etc. can be mentioned.

[0065] The printed matter manufactured according to the present invention is applicable to various base materials, various printed matter for books, various printed matter for packaging such as paper, various plastic printed matter, printed matter for seals / labels, art printed matter, metal printed matter (printed matter for beverage cans, food printed matter such as canned foods, etc.), printed matter such as packaging containers, etc.

[0066] In the present invention, there is no particular limitation on the method of curing the ink with active energy rays, and known ones can be used as the active energy ray source. Specifically, mercury lamps, xenon lamps, metal halide lamps, ultraviolet light-emitting diodes (UV-LEDs), light-emitting diodes (LEDs) such as ultraviolet laser diodes (UV-LDs), electron beams, gas / solid lasers, etc. can be mentioned.

Examples

[0067] Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples do not limit the scope of rights of the present invention in any way. In the present invention, "part" represents "part by mass", and "%" represents "% by mass".

[0068] (Weight average molecular weight) In the present invention, the weight average molecular weight of was measured by gel permeation chromatography (HLC-8320) manufactured by Tosoh Corporation. The calibration curve was prepared using standard polystyrene samples. The eluent was tetrahydrofuran, and three TSKgel SuperHM-M (manufactured by Tosoh Corporation) columns were used. The measurement was carried out at a flow rate of 0.6 ml / min, an injection volume of 10 μl, and a column temperature of 40°C.

[0069] (Production Example 1) Into a four-necked flask equipped with a stirrer, a cooler, a thermometer, and a gas inlet tube, 71.6 parts of MIRAMER M500 (a mixture with a (meth)acrylic compound) as a (meth)acrylic compound (a1) having one or more hydroxyl groups, 11.9 parts of toluene-2,4-diisocyanate as an isocyanate compound (a3), 9.2 parts of MIRAMER M600 and 5.0 parts of LAROMER LR8863 as (meth)acrylic compounds, 0.01 part of tin 2-ethylhexanoate as a catalyst, and 0.2 part of tertiary butyl hydroquinone as a polymerization inhibitor were placed, and air was blown in while stirring, and the reaction was carried out at 100 °C for 1 hour. Next, 2.1 parts of glycerin was added as a polyol compound (a2) other than (a1), and the reaction was further carried out at 110 °C for 5 hours to obtain Resin Composition 1. The value of [(a1') / (a3')] in this reaction was 0.5, and the (meth)acrylic group concentration of the obtained urethane acrylate (A) was 6.86 mmol / g.

[0070] (Production Examples 2 to 9, 13 to 14) According to the composition in Table 1, Resin Compositions 2 to 9 and 13 to 14 were obtained in the same manner as in Production Example 1 except that each raw material was changed.

[0071] (Production Example 10) In a four-necked flask equipped with a stirrer, a cooler, a thermometer, and a gas inlet tube, 67.1 parts of MIRAMER M500 (a mixture with a (meth)acrylic compound) as a (meth)acrylic compound (a1) having one or more hydroxyl groups, 11.1 parts of toluene-2,4-diisocyanate as an isocyanate compound (a3), 11.5 parts of MIRAMER M600 and 5.0 parts of LAROMER LR8863 as (meth)acrylic compounds, 0.01 part of tin 2-ethylhexanoate as a catalyst, and 0.2 part of tertiary butyl hydroquinone as a polymerization inhibitor were placed. While stirring, air was blown in and the reaction was carried out at 100 °C for 1 hour. Next, 0.5 part of N-methyldiethanolamine and 4.6 parts of Sunnex GP-250 were added as polyol compounds (a2) other than (a1), and the reaction was further carried out at 110 °C for 5 hours to obtain a resin composition 10. The value of [(a1') / (a3')] in this reaction was 0.5, and the (meth)acrylic group concentration of the obtained urethane acrylate (A) was 6.43 mmol / g.

[0072] (Production Examples 11 to 12) Resin compositions 11 to 12 were obtained in the same manner as in Production Example 10 except that each raw material was changed according to the composition in Table 1.

[0073]

Table 1

[0074] The details of the materials described in Table 1 are described below. ·(Meth)acrylic compound (a1) MIRAMER M500: Manufactured by Miwon Specialty Chemical Co., Ltd., a mixture of dipentaerythritol pentaacrylate / dipentaerythritol hexaacrylate = 50 / 50 (mass ratio) Biscoat #802: Manufactured by Osaka Organic Chemical Industry Co., Ltd., polypentaerythritol polyacrylate ·Polyol compound (a2) Sunnex PP-600: Manufactured by Sanyo Chemical Industries, Ltd., polypropylene glycol Sunnex GP-250: Manufactured by Sanyo Chemical Industries, Ltd., propylene oxide-modified glycerin Sunnex PP-1200: Manufactured by Sanyo Chemical Industries, Ltd., polypropylene glycol · (Meth)acrylic compound MIRAMER M600: Manufactured by American Specialty Chemicals Co., Ltd., dipentaerythritol hexaacrylate LAROMER LR8863: Manufactured by BASF, ethylene oxide-modified trimethylolpropane triacrylate · Polymerization inhibitor TBHQ: Tertiary butylhydroquinone

[0075] (Manufacturing example of polyester resin) Into a four-necked flask equipped with a stirrer, Dean-Stark tube, thermometer, and gas inlet tube, 10 parts of glycerin, 20 parts of ethylene glycol, and 59 parts of phthalic anhydride were placed as raw materials, and the mixture was heated to 220 °C with stirring. The reaction was carried out while removing the condensed water generated during the progress of the reaction outside the system, and the reaction was terminated when the theoretical amount of water was removed, and a polyester resin with a weight average molecular weight of 10,500 was obtained.

[0076] (Manufacturing example of rosin-modified resin) 27.0 parts of gum rosin and 17.0 parts of maleic anhydride were charged into a four-necked flask equipped with a stirrer, a reflux condenser with a water separator, and a thermometer, and the reaction mixture was obtained by heating at 180 °C for 1 hour while blowing nitrogen gas. 31.9 parts of benzoic acid, 8.0 parts of trimethylolpropane, 16.0 parts of pentaerythritol, and 0.1 part of p-toluenesulfonic acid monohydrate as a catalyst were added to the reaction mixture, and a dehydration condensation reaction was carried out at 230 °C for 10 hours to obtain a rosin-modified resin with a weight average molecular weight of 28,000.

[0077] (Manufacturing example of varnish A) Into a four-necked flask equipped with a stirrer, a Dean-Stark tube, a thermometer, and a gas inlet tube, 35 parts of DAISO DAP A, 10 parts of EBECRYL 1142, and 55 parts of LAROMER LR8863 were placed, heated to 100 °C while stirring, and stirred and melted at 100 °C for 2 hours to obtain varnish A.

[0078] (Varnish Production Examples B - H) According to the composition in Table 2, varnishes B - H were obtained in the same manner as Varnish Production Example A except that each raw material was changed.

[0079]

Table 2

[0080] The details of the materials described in Table 2 are described below. · Resin DAISO DAP A: It has a ring structure. Weight average molecular weight 30,000, diallyl phthalate resin manufactured by Osaka Soda Co., Ltd. DAISO ISODAP: It has a ring structure. Weight average molecular weight 35,000, diallyl phthalate resin (diallyl isophthalate resin) manufactured by Osaka Soda Co., Ltd. RADPAR AD032: It has a ring structure. Weight average molecular weight 32,000, allyl resin manufactured by Osaka Soda Co., Ltd. PETROTACK 90: It has a ring structure. Weight average molecular weight 1,600, petroleum resin manufactured by Toray Industries, Inc. Funakoshi Flax 2: It does not have a ring structure. Polymerized linseed oil manufactured by Toshin Yushi Co., Ltd. Quintone B170: It does not have a ring structure. Petroleum resin manufactured by Nippon Zeon Co., Ltd. · (Meth)acrylic compound EBECRYL 1142: Ditrimethylolpropane tetraacrylate manufactured by Daicel Ornex Co., Ltd.

[0081] (Examples 1 - 33, Comparative Examples 1 - 7) According to the composition in Table 3, the active energy ray-curable inks of Examples 1 to 33 and Comparative Examples 1 to 7 were obtained by kneading with a three-roll mill. As a method for evaluating the printability of the obtained active energy ray-curable inks, "ink mist" and "ink pot escape" on a printing press were examined, and as a method for evaluating curability, "moisture and heat blocking" of the printed matter was examined, and "dot gain" was examined as a method for evaluating the sharpness of the printed matter. The results are shown in Table 3 together.

[0082] <Measurement method of ink mist> Printing was carried out at a speed of 10,000 sheets per hour under the following conditions using an offset sheet-fed printing press LITHRONE26 (Komori Corporation). During printing, white paper was attached to the inside of the safety cover of the printing press, and after 10,000 sheets, the white paper was taken out and the degree of ink scattering was evaluated. 4, 3, and 2 are at the practical level. (Evaluation criteria) 4: A small amount of ink mist is scattered on a part of the white paper. 3: The ink mist is thinly scattered over the entire surface of the white paper. 2: The ink mist is scattered rather thickly over the entire surface of the white paper. 1: The ink mist is scattered thickly over the entire surface of the white paper. (Printing conditions) Printing press: LITHRONE26 (manufactured by Komori Corporation) Paper: OK Top Coat+ (79.1 g / m 2 ), manufactured by Oji Paper Co., Ltd. Printing speed: 10,000 sheets per hour Lamp: Metal halide lamp (output 120 W / cm, 1 lamp used), manufactured by Eye Graphics Co., Ltd.

[0083] <Evaluation method of ink pot escape> The presence or absence of "ink pot escape" trouble in which the ink is not scraped off by the supply roller in the ink pot during printing was observed in the same manner as above. 4, 3, and 2 are at the practical level. (Evaluation criteria) 4: Does not occur for 60 minutes or more. 3: Does not occur for 30 minutes or more and less than 60 minutes. 2: It does not occur for more than 10 minutes and less than 30 minutes 1: It occurs within less than 10 minutes

[0084] <Dot gain evaluation method> Using the printed matter obtained by the above printing, the dot gain, which indicates how much the 50% halftone dots on the printed surface expand during continuous printing of 5,000 sheets, was compared. A dot gain evaluation score of 2 or more is a practically acceptable level. A score of 3 or more is more preferable and can provide a clear printed matter (Evaluation criteria) 4: Dot gain is less than 19%, and a clear printed matter that fully meets market requirements can be provided 3: Dot gain is 19% or more and less than 22%, and a printed matter at a level acceptable to the market can be provided 2: Dot gain is 22% or more and less than 25%, which is the lower limit level acceptable to the market 1: Dot gain is 25% or more, and it does not meet market requirements

[0085] <Wet heat blocking evaluation method> Using an RI tester (a simple color development machine), ink was developed on coated paper (OK Top Coat Plus manufactured by Oji Paper Co., Ltd.) at a coating amount of 1 g / m 2 Then, using a metal halide lamp (manufactured by Eye Graphics Co., Ltd., output: 96 W / cm, lamp distance: 10 cm), the conveyor speed was changed (80, 100, 120 m / min) to cure and obtain a printed matter. Next, the printed matter was cut out into a 4 cm × 5 cm square, and the ink-printed surfaces were overlapped. Under the conditions of temperature: 40°C, humidity: 80% RH, load: 2 kg / cm 2 After blocking for 24 hours, the printed matter was evaluated. Ratings of 4, 3, and 2 are practical levels (Evaluation criteria) 4: No change in the printed surface 3: Peeling is observed on a part of the printed surface (less than 10% of the area) 2: Peeling is observed on a part of the printed surface (10% or more and less than 50% of the area) 1: Peeling is observed on a part of the printed surface (50% or more of the area) or on the entire surface

[0086]

Table 3

[0087]

Table 3

[0088]

Table 3

[0089] The details of the materials described in Table 3 are described below. · (Meth)acrylic compound OTA480: Propylene oxide-modified glycerin triacrylate manufactured by Daicel Ornex Co., Ltd. · Pigment Carbon black: Carbon black MA11 manufactured by Mitsubishi Chemical Corporation · Photoinitiator Omnirad379EG: 2-Dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one manufactured by iGM RESINS KAYACURE DETX-S: 2,4-Diethylthioxanthone manufactured by Nippon Kayaku Co., Ltd.

[0090] In Examples 1 to 33 of the present invention, the evaluations of "ink mist" and "ink pot escape", "humid heat blocking", and "dot gain" were good. On the other hand, in Comparative Example 1, the humid heat blocking deteriorated because the (meth)acryloyl group concentration of urethane (meth)acrylate (A) was less than 4.0 mmol / g. Further, in Comparative Example 2, the viscoelasticity and fluidity of the ink were insufficient, and the ink mist and ink pot escape deteriorated. Furthermore, in Comparative Examples 3 to 6 where the resin (C) having a ring structure was not used, the dot gain deteriorated. In Comparative Example 7 where urethane (meth)acrylate (A) was not used, the humid heat blocking deteriorated. From the above, it was found that the present invention can obtain an active energy ray-curable ink that suppresses ink mist and ink pot leakage, has excellent curability, and can provide a clear printed matter with little dot gain.

Claims

1. An active energy ray-curable ink containing urethane (meth)acrylate (A) and a resin (C) having a ring structure, wherein the (meth)acryloyl group concentration of the urethane (meth)acrylate (A) is in the range of 4.0 to 8.0 mmol / g, which is characterized as an active energy ray-curable ink.

2. The active energy ray-curable ink according to Claim 1, wherein the urethane (meth)acrylate (A) is a reaction product of a (meth)acrylic compound (a1) having one or more hydroxyl groups, a polyol compound (a2) other than (a1), and an isocyanate compound (a3).

3. The active energy ray-curable ink according to Claim 1, wherein the resin (C) having a ring structure has a weight average molecular weight of 1,000 to 100,000.

4. The active energy ray-curable ink according to Claim 1, wherein the resin (C) having a ring structure contains one or more selected from the group consisting of allyl resin, diallyl phthalate resin, rosin, maleated rosin, acrylated rosin, rosin-modified resin, epoxy resin, polyester resin, polyurethane resin, alkyd resin, and petroleum resin.

5. The active energy ray-curable ink according to Claim 1, further comprising a (meth)acrylic compound (excluding the cases where it is (A) and (C)).

6. The active energy ray-curable ink according to Claim 2, wherein the hydroxyl value of the polyol compound (a2) is 125 to 1850 mgKOH / g.

7. The active energy ray-curable ink according to Claim 2, wherein the ratio [(a1') / (a3')] of the number of moles of hydroxyl groups (a1') contained in the (meth)acrylic compound (a1) having one or more hydroxyl groups to the number of moles of isocyanate groups (a3') contained in the isocyanate compound (a3) is in the range of 0.2 to 0.

6.

8. A method for producing the active energy ray-curable ink according to Claim 2, comprising a step of reacting a (meth)acrylic compound (a1) having one or more hydroxyl groups, a polyol compound (a2) other than (a1), and an isocyanate compound (a3) in a (meth)acrylic compound (excluding the cases where it is (A) and (C)) to obtain urethane (meth)acrylate (A).

9. A printed matter characterized by having a cured product of the active energy ray-curable ink according to any one of claims 1 to 7 on a substrate.

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