Active energy ray-curable ink composition

Abstract

The present invention provides an active energy ray-curable ink composition having excellent ink misting resistance (scattering suppression ability) and excellent drying properties. This active energy ray-curable ink composition is characterized by containing a pigment (A), an allyl polymer (B) obtained by polymerizing an allyl compound represented by general formula (I), an ethylenically unsaturated compound (C), and a photopolymerization initiator (D), and the content of the photopolymerization initiator (D) in the active energy ray-curable ink composition is 5.0 mass% or more. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to an active energy ray-curable ink composition. Background Art

[0002] Conventionally, various resin compositions that are cured by light (e.g., ultraviolet rays) have been used for inks, coatings, adhesives, photoresists, etc. For example, active energy ray-curable ink compositions are highly regarded for their fast curing speed, curing in a short time, environmental friendliness without the use of solvents, and resource and energy conservation, and have been widely used.

[0003] In this case, the active energy ray-curable ink composition includes a compound such as an acrylate compound that is curable to active energy rays (hereinafter referred to as an active energy ray-curable compound). Therefore, when irradiated with active energy rays, the ink composition will instantly cure to form a tough coating based on three-dimensional crosslinking of the active energy ray-curable compound. In addition, since the ink composition can be instantly cured, subsequent processing can be performed immediately after printing. Based on these advantages, the active energy ray-curable ink composition is suitable for packaging packaging printing that requires a strong coating to improve productivity and protect the design, as well as printing plate printing in the commercial field.

[0004] Generally, active energy ray-curable ink compositions (hereinafter also referred to as "ink") are required to have printing properties such as emulsification suitability, smear resistance, and initial concentration stability. In addition to the above printing properties, the inks are also required to have printing film suitability such as curability, glossiness, and adhesion, and printing film strength such as abrasion resistance and solvent resistance.

[0005] A typical active energy ray-curable ink composition (hereinafter, also simply referred to as "ink") contains a binder and a pigment as solid components, and the binder is a component that forms a coating. The binder contains: a resin component (referred to as a binder resin) containing an active energy ray-curable compound such as a resin and an acrylate compound; a photopolymerization initiator; and various additives as required. In addition, in order to meet the above requirements, unsaturated polyester resins, epoxy acrylate resins, polyurethane acrylate resins, polyester acrylate resins, etc. have been studied as binder resins for active energy ray-curable ink compositions.

[0006] For example, Patent Document 1 discloses a binder resin obtained by modifying a saturated polyester with an isocyanate group-containing urethane acrylate.

[0007] In addition, as an active energy ray-curable ink composition, for example, an active energy ray-curable flatbed offset ink composition is proposed, which comprises: 30% of an acrylate-added disproportionated rosin alkyd resin obtained by reacting 133 parts of disproportionated rosin, 133 parts of benzoic acid, 130 parts of phthalic acid and 173 parts of trimethylolpropane, 59.9% of dipentaerythritol hexaacrylate, and 0.1% of hydroquinone (for example, refer to Patent Document 2 (Example 1)).

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2001-348516

[0011] Patent Document 2: Japanese Patent Application Publication No. 2007-231220 Summary of the invention

[0012] Problem that the invention aims to solve

[0013] As such an active energy ray-curable ink composition, it is required to improve the ink flying resistance (scattering inhibition property) from the viewpoint of high-speed printing and mass printing. However, the present inventors have studied and found that the ink flying resistance (scattering inhibition property) of the active energy ray-curable ink composition is not sufficient.

[0014] The present invention solves a new problem found by the present inventors, and an object of the present invention is to provide an active energy ray-curable ink composition having excellent ink flying resistance and also excellent drying properties.

[0015] Solutions for solving problems

[0016] The inventors of the present invention have conducted intensive research and found that an active energy ray-curable ink composition comprising a pigment (A), an allyl polymer (B) obtained by polymerization of an allyl compound represented by the general formula (I), an ethylenically unsaturated compound (C), and a specific amount of a photopolymerization initiator (D) has excellent ink resistance to flying, and thus conceived the present invention.

[0017] That is, the present invention (1) relates to an active energy ray-curable ink composition, characterized in that it contains a pigment (A), an allyl polymer (B) obtained by polymerizing an allyl compound represented by the general formula (I), an ethylenically unsaturated compound (C), and a photopolymerization initiator (D),

[0018] The content of the photopolymerization initiator (D) in the active energy ray-curable ink composition is 5.0% by mass or more.

[0019]

[0020] [R 1 and R 2 Represent H or CH3,

[0021] X is an a-valent alicyclic hydrocarbon group or an a-valent aromatic hydrocarbon group. a represents 2 or 3.]

[0022] The present invention (2) relates to the active energy ray-curable ink composition according to the present invention (1), characterized in that:

[0023] The photopolymerization initiator (D) includes an intramolecular cleavage type photopolymerization initiator (d-1) and a hydrogen abstraction type photopolymerization initiator (d-2).

[0024] The present invention (3) relates to the active energy ray-curable ink composition according to the present invention (2), wherein the intramolecular cleavage type photopolymerization initiator (d-1) is at least one selected from the group consisting of α-hydroxyalkylphenone-based photopolymerization initiators, α-aminoalkylphenone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators,

[0025] The hydrogen abstraction type photopolymerization initiator (d-2) is at least one selected from the group consisting of benzophenone-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and ketosulfone-type photopolymerization initiators.

[0026] The present invention (4) relates to the active energy ray-curable ink composition according to any one of the present inventions (1) to (3), further comprising a photoinitiator auxiliary (d-3).

[0027] The present invention (5) relates to the active energy ray-curable ink composition according to any one of the present inventions (1) to (4), wherein X in the general formula (I) has any of the following cyclic skeletons.

[0028]

[0029] The present invention (6) relates to the active energy ray-curable ink composition according to any one of the present inventions (1) to (4), wherein X in the general formula (I) is an aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0030] The present invention (7) relates to the active energy ray-curable ink composition according to any one of the present inventions (1) to (4), wherein X in the general formula (I) has the following cyclic skeleton.

[0031]

[0032] Effects of the Invention

[0033] The active energy ray-curable ink composition of the present invention contains a pigment (A), an allyl polymer (B) obtained by polymerizing an allyl compound represented by general formula (I), an ethylenically unsaturated compound (C), and a photopolymerization initiator (D), and the content of the photopolymerization initiator (D) in the ink composition has been adjusted to a prescribed range. Therefore, the ink composition has excellent ink flying resistance and further excellent drying properties. DETAILED DESCRIPTION

[0034] Hereinafter, the present invention will be described in detail.

[0035] The reason why the above-mentioned active energy ray-curable ink composition can obtain the above-mentioned effects is presumed as follows.

[0036] The allyl polymer (B) obtained by polymerizing the allyl compound represented by the general formula (I) has excellent ink flying resistance and drying properties, but when the allyl polymer (B) obtained by polymerizing the allyl compound represented by the general formula (I) is combined with a pigment (A), an ethylenically unsaturated compound (C) and a specific amount of a photopolymerization initiator (D), better ink flying resistance and drying properties can be obtained.

[0037] Pigment (A)

[0038] The pigment used in the active energy ray-curable ink composition of the present invention is not particularly limited, and organic or inorganic pigments can be used alone or in combination of two or more. Among the pigments, pigments with high color development and high heat resistance are preferred, and organic pigments are generally used, but not limited thereto. Among them, as described above, pigments generally contain alkaline polar functional groups and / or acidic polar functional groups, but pigments having alkaline polar functional groups and / or acidic polar functional groups are preferred.

[0039] The pigments that can be used in the present invention are not particularly limited, and examples thereof include: soluble azo pigments, insoluble azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, isoindolinone pigments, perylene pigments, pyrenone pigments, dioxazine pigments, anthraquinone pigments, dianthraquinone pigments, anthrapyrimidine pigments, anthranthrone pigments, indanthrone pigments, flavanthron pigments, pyranthrone pigments, or diketopyrrolopyrrole pigments, etc.

[0040] If specific examples are further shown by the common names of the pigment index, the following can be cited:

[0041] Blue pigments such as Pigment Black 7, Pigment Blue 15, Pigment Blue 15:1, Pigment Blue 15:3, Pigment Blue 15:4, Pigment Blue 15:6, Pigment Blue 22, Pigment Blue 60, or Pigment Blue 64;

[0042] Green pigments such as Pigment Green 7, Pigment Green 36, or Pigment Green 58;

[0043] Red pigments such as Pigment Red 9, Pigment Red 48, Pigment Red 49, Pigment Red 52, Pigment Red 53, Pigment Red 57, Pigment Red 97, Pigment Red 122, Pigment Red 123, Pigment Red 144, Pigment Red 146, Pigment Red 149, Pigment Red 166, Pigment Red 168, Pigment Red 177, Pigment Red 178, Pigment Red 179, Pigment Red 180, Pigment Red 185, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Red 215, Pigment Red 216, Pigment Red 217, Pigment Red 220, Pigment Red 221, Pigment Red 223, Pigment Red 224, Pigment Red 226, Pigment Red 227, Pigment Red 228, Pigment Red 238, Pigment Red 240, Pigment Red 242, Pigment Red 254, or Pigment Red 255;

[0044] Purple pigments such as pigment violet 19, pigment violet 23, pigment violet 29, pigment violet 30, pigment violet 37, pigment violet 40, or pigment violet 50;

[0045] Yellow pigments such as pigment yellow 12, pigment yellow 13, pigment yellow 14, pigment yellow 17, pigment yellow 20, pigment yellow 24, pigment yellow 74, pigment yellow 83, pigment yellow 86, pigment yellow 93, pigment yellow 94, pigment yellow 95, pigment yellow 109, pigment yellow 110, pigment yellow 117, pigment yellow 120, pigment yellow 125, pigment yellow 128, pigment yellow 137, pigment yellow 138, pigment yellow 139, pigment yellow 147, pigment yellow 148, pigment yellow 150, pigment yellow 151, pigment yellow 153, pigment yellow 154, pigment yellow 155, pigment yellow 166, pigment yellow 168, pigment yellow 180, pigment yellow 185, or pigment yellow 213;

[0046] Orange pigments such as pigment orange 13, pigment orange 36, pigment orange 37, pigment orange 38, pigment orange 43, pigment orange 51, pigment orange 55, pigment orange 59, pigment orange 61, pigment orange 64, pigment orange 71, or pigment orange 74; or,

[0047] Brown pigments such as Pigment Brown 23, Pigment Brown 25, or Pigment Brown 26.

[0048] In addition, any carbon black such as neutral, acidic or basic can be used as Pigment Black 7, and acidic ones are preferred. As white pigments, titanium oxide, zinc oxide and the like can be used.

[0049] The active energy ray-curable ink composition may use a dye in addition to a pigment, and Food Red 3, 3:1, 7, 9, 17, 17:1, Food Blue 2, 2:1, Food Yellow 3, Food Black 1, 2, Food Blown 3, etc. are particularly preferred from the viewpoint of safety.

[0050] In order to ensure a sufficient color gamut of printed matter, the amount of pigment (A) added is preferably contained in the active energy ray-curable ink composition in the range of 5 to 65 mass %. The lower limit is more preferably 10 mass % or more, and the upper limit is more preferably 60 mass % or less, further preferably 55 mass % or less, particularly preferably 40 mass % or less, and most preferably 30 mass % or less.

[0051] Allyl polymer (B)

[0052] The active energy ray-curable ink composition of the present invention is characterized by containing an allyl polymer (B) obtained by polymerizing an allyl compound represented by general formula (I). The allyl polymer (B) can be used alone or in combination of two or more.

[0053]

[0054] [R 1 and R 2 Represent H or CH3,

[0055] X is an a-valent alicyclic hydrocarbon group or an a-valent aromatic hydrocarbon group. a represents 2 or 3.]

[0056] X in formula (I) is either an a-valent alicyclic hydrocarbon group or an a-valent aromatic hydrocarbon group. X in formula (I) is preferably an a-valent alicyclic hydrocarbon group because of its excellent compatibility with ethylenically unsaturated compounds.

[0057] (i) a-valent alicyclic hydrocarbon group

[0058] When X in the formula (1) is an a-valent alicyclic hydrocarbon group, the carbon number is preferably 3 to 18, more preferably 4 to 12, and particularly preferably 4 to 8.

[0059] The a-valent alicyclic hydrocarbon group may be a saturated a-valent alicyclic hydrocarbon group or may have an unsaturated bond in part. In the present invention, the alicyclic hydrocarbon group refers to a hydrocarbon group having a non-aromatic cyclic structure.

[0060] In the formula (I), when X is an a-valent alicyclic chain hydrocarbon group, a is preferably 2 or 3, and more preferably 2.

[0061] In addition, the a-valent alicyclic hydrocarbon group may have an alkyl group. The alkyl group may be a straight chain or branched chain having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, more preferably methyl or ethyl. The alkyl group may be present at one or more substitutable positions of the alicyclic hydrocarbon group. It should be noted that the a-valent alicyclic hydrocarbon group does not necessarily have an alkyl group. The a-valent alicyclic hydrocarbon group preferably has no substituent.

[0062] When X in the formula (I) is an a-valent alicyclic hydrocarbon group, X is preferably a saturated or partially unsaturated 4- to 8-membered ring skeleton having no substituent.

[0063] When X in the formula (I) is an a-valent alicyclic hydrocarbon group, the following cyclic skeletons can be exemplified as preferred examples of X in the above general formula (I).

[0064]

[0065] When X in the formula (I) is an a-valent alicyclic hydrocarbon group, more preferable examples of X in the general formula (I) include the following cyclic skeletons.

[0066]

[0067] When X in the formula (I) is an a-valent alicyclic hydrocarbon group, the following cyclic skeletons can be exemplified as further preferred examples of X in the above general formula (I).

[0068]

[0069] X may be in various forms and may be a cyclic skeleton other than the above. When the cyclic skeleton is partially unsaturated, the number of double bonds in the cyclic skeleton is not limited to 1 and may be 2 or more.

[0070] X may be cross-linked within the molecule, and examples of X that is cross-linked within the molecule include adamantane, norbornene, and norbornane.

[0071] X is an a-valent group, a is 2 or 3, and therefore, X is a divalent or trivalent group. On the cyclic skeleton of X, the allyl ester group [-CO-O-CH2-CR 2 =CHR 1 ] is combined with a (2 or 3) groups. R of the allyl ester group shown in the general formula (I) 1 is H or CH3, R 2 It is H or CH3.

[0072] The allyl ester group [-CO-O-CH2-CR 2 =CHR 1] can be any combination of substitution positions, and the allyl compound can be a mixture of substances having different combinations of substitution positions. In particular, when two allyl ester groups are combined with X of a 6-membered ring, the two allyl ester groups can be any one of ortho-, meta-, or para-oriented, preferably ortho-oriented or para-oriented, more preferably ortho-oriented.

[0073] Specific examples of the allyl compounds represented by the general formula (I) include 1,2-cyclohexanedicarboxylic acid diallyl ester, 1,3-cyclohexanedicarboxylic acid diallyl ester, 1,4-cyclohexanedicarboxylic acid diallyl ester, 4-cyclohexene-1,2-dicarboxylic acid diallyl ester, 2-cyclohexene-1,2-dicarboxylic acid diallyl ester, etc. Among them, 1,2-cyclohexanedicarboxylic acid diallyl ester, 4-cyclohexene-1,2-dicarboxylic acid diallyl ester, and 1,4-cyclohexanedicarboxylic acid diallyl ester are preferred, and 1,2-cyclohexanedicarboxylic acid diallyl ester is more preferred.

[0074] (ii) a-valent aromatic hydrocarbon group

[0075] When X in the formula (I) is an a-valent aromatic hydrocarbon group, it is preferably any one of aromatic hydrocarbon groups having 6 to 20 carbon atoms, and more preferably any one of aromatic hydrocarbon groups having 6 to 12 carbon atoms.

[0076] In the formula (I), when X is an a-valent aromatic hydrocarbon group, a is preferably 2 or 3, and more preferably 2.

[0077] In addition, the a-valent aromatic hydrocarbon group may have an alkyl group. The alkyl group may be a straight chain or branched chain having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, more preferably methyl or ethyl. The alkyl group may be present in one or more substitutable positions of the aromatic hydrocarbon group. It should be noted that the a-valent aromatic hydrocarbon group does not necessarily have an alkyl group. The a-valent aromatic hydrocarbon group preferably has no substituent.

[0078] When X in the formula (I) is an a-valent aromatic hydrocarbon group, X is preferably an aromatic 6- to 8-membered ring skeleton having no substituent.

[0079] When X in the formula (I) is an a-valent aromatic hydrocarbon group, the following cyclic skeletons can be exemplified as preferred examples of X in the above general formula (I).

[0080]

[0081] When X in formula (I) is an a-valent aromatic hydrocarbon group, the substitution position of the allyl ester (COOCH2CH=CH2) group on the ring may be any combination or a mixture thereof. In particular, when two COOCH2CH=CH2 groups are combined with a 6-membered ring, the two COOCH2CH=CH2 groups may be in any one of ortho, meta or para orientations, preferably in ortho or meta orientations.

[0082] Specific examples of the allyl compound when X in the formula (I) is an a-valent aromatic hydrocarbon group include diallyl phthalate and diallyl isophthalate.

[0083] The allyl polymer (B) obtained by polymerizing at least one selected from the group consisting of the above-mentioned allyl compounds can be used in the active energy ray-curable ink composition. In addition, the allyl compound represented by the above-mentioned general formula (I) and other polymerizable compounds can also be used in the active energy ray-curable ink composition.

[0084] Examples of methods for obtaining the compounds given as specific examples of the allyl compounds represented by the general formula (I) include: a method of subjecting cyclohexanedicarboxylic acid or cyclohexanedicarboxylic anhydride to an esterification reaction with allyl alcohol or allyl chloride; and a method of subjecting cyclohexenedicarboxylic acid or cyclohexenedicarboxylic anhydride to an esterification reaction with allyl alcohol or allyl chloride.

[0085] Furthermore, commercially available products of the compounds listed as specific examples of the allyl compounds represented by the above general formula (I) may also be used.

[0086] In addition, for example, the allyl compound represented by the above general formula (I) can also be produced according to the method described in Japanese Patent Application Laid-Open No. 2019-19291.

[0087] The polymerization method of the allyl compound shown in the above general formula (I) is not particularly limited, and a common polymerization reaction can be used. In the above polymerization reaction, a polymerization initiator can be appropriately added as needed. By using a polymerization initiator, a polymer with a higher molecular weight can be obtained in a short time.

[0088] Examples of the polymerization initiator used in the polymerization reaction of the allyl compound include azo initiators such as azobisisobutyronitrile and dimethyl 2,2'-azobisisobutyrate; and peroxide initiators such as ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, and benzoyl peroxide.

[0089] The amount of the polymerization initiator is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and particularly preferably 0.001 to 3.0 parts by mass, based on 100 parts by mass of the monomer of the allyl compound represented by the general formula (I).

[0090] The reaction temperature during polymerization is 60 to 240° C., for example, preferably 80 to 220° C. The reaction time is 0.1 to 100 hours, for example, preferably 1 to 30 hours.

[0091] By polymerizing the allyl compound represented by the above general formula (I) by the above method or the like, an allyl polymer (A) having monomer units based on the allyl compound represented by the above general formula (I) can be prepared.

[0092] In addition, for example, the allyl polymer (A) can also be produced according to the method described in JP-A-2019-19291.

[0093] In 100% by mass of the allyl polymer (B), the content of the monomer units based on the allyl compound represented by the above-mentioned general formula (I) is preferably 20% by mass or more, more preferably 50% by mass or more, further preferably 80% by mass or more, particularly preferably 98% by mass or more, and may also be 100% by mass.

[0094] The weight average molecular weight of the allyl polymer (B) is preferably 300,000 or less, more preferably 200,000 or less, further preferably 2,000 to 150,000, particularly preferably 5,000 to 140,000.

[0095] The weight average molecular weight of the allyl polymer (B) is measured by the method described in Examples.

[0096] The content of the allyl polymer (B) in the active energy ray-curable ink composition of the present invention is preferably 1 to 60% by mass, more preferably 1 to 55% by mass, and further preferably 1 to 50% by mass relative to the total amount of the active energy ray-curable ink composition. The lower limit is preferably 5% by mass or more, and the upper limit is particularly preferably 40% by mass or less, and most preferably 30% by mass or less. When the content of the allyl polymer (B) exceeds 60% by mass, the solubility in the ethylenically unsaturated compound (C) deteriorates, the viscosity also increases, and sometimes the handling property deteriorates. When the content of the allyl polymer (B) is less than 1% by mass, sometimes the resulting active energy ray-curable ink composition cannot obtain sufficient drying properties.

[0097] Ethylenically unsaturated compounds (C)

[0098] The active energy ray-curable ink composition of the present invention preferably contains an ethylenically unsaturated compound (C) that can be cured by light irradiation. The ethylenically unsaturated compound (C) preferably has 1 to 20, more preferably 1 to 10, and further preferably 2 to 6 carbon-carbon double bonds. Examples of the ethylenically unsaturated compound (C) include: (meth)acrylate compounds, (meth)allyl compounds, and vinyl compounds. In addition, the ethylenically unsaturated compound can be used alone or as a mixture of two or more compounds.

[0099] Examples of the (meth)acrylate compound include: (meth)acrylate compounds of alcohols such as pentaerythritol, dipentaerythritol, trimethylolpropane, di(trimethylol)propane, neopentyl glycol, 1,6-hexanediol, glycerol, polyethylene glycol, and polypropylene glycol, and (meth)acrylate compounds obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to these alcohols; (meth)acrylate compounds obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to bisphenols such as bisphenol A and bisphenol F; (meth)acrylate compounds such as epoxy (meth)acrylate, polyurethane (meth)acrylate, and alkyd (meth)acrylate; epoxy (meth)acrylates; The (meth)acrylate compounds such as soybean oil acrylate are preferably (meth)acrylate compounds of alcohols such as pentaerythritol, dipentaerythritol, trimethylolpropane, di(trimethylol)propane, neopentyl glycol, 1,6-hexanediol, glycerol, polyethylene glycol, polypropylene glycol, and (meth)acrylate compounds obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to them; more preferably (meth)acrylate compounds of alcohols such as pentaerythritol, dipentaerythritol, trimethylolpropane, di(trimethylol)propane, and (meth)acrylate compounds obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to them.

[0100] Examples of the (meth)allyl compound include di(meth)allyl phthalate and tri(meth)allyl isocyanurate.

[0101] Examples of the vinyl compound include styrene, divinylbenzene, N-vinylpyrrolidone, and vinyl acetate.

[0102] Among them, from the viewpoint of compatibility with the allyl polymer (B) and curability during photocuring, pentaerythritol tetraacrylate and glycerol triacrylate to which alkylene oxide is added are preferred; and pentaerythritol tetraacrylate to which alkylene oxide is added is more preferred.

[0103] The content of the ethylenically unsaturated compound (C) contained in the active energy ray-curable ink composition of the present invention is preferably 50 to 400 parts by mass, more preferably 50 to 300 parts by mass, and even more preferably 50 to 275 parts by mass, based on 100 parts by mass of the allyl polymer (B) in the active energy ray-curable ink composition.

[0104] Photopolymerization initiator (D)

[0105] The active energy ray-curable ink composition of the present invention contains a photopolymerization initiator. The photopolymerization initiator can be used alone or in combination of two or more. There are no particular restrictions on the photopolymerization initiator that can be used in the present invention, and a known photopolymerization initiator can be used. As a specific example, an intramolecular cleavage type photopolymerization initiator (d-1) and a hydrogen abstraction type photopolymerization initiator (d-2) are preferably used. As a result, there is a tendency to obtain better ink flying resistance and drying properties.

[0106] In order to obtain better drying properties, the content of the photopolymerization initiator (D) contained in the active energy ray-curable ink composition may be 5.0% by mass or more, preferably 5.4% by mass or more, more preferably 5.6% by mass or more, further preferably 5.8% by mass or more, particularly preferably 6.0% by mass or more, most preferably 6.2% by mass or more, and most preferably 6.5% by mass or more, relative to the total amount of the active energy ray-curable ink composition. The upper limit of the photopolymerization initiator (D) in the active energy ray-curable ink composition is not particularly limited, and may be, for example, 15% by mass or less, preferably 14% by mass or less, and more preferably 13% by mass or less. As a result, there is a tendency to obtain better ink flying resistance and drying properties.

[0107] Intramolecular cleavage type photopolymerization initiator (d-1)

[0108] Examples of the intramolecular cleavage type photopolymerization initiator (d-1) include α-hydroxyalkylphenone type photopolymerization initiators, α-aminoalkylphenone type photopolymerization initiators, acylphosphine oxide type photopolymerization initiators, etc. The intramolecular cleavage type photopolymerization initiator (d-1) may be used alone or in combination of two or more.

[0109] Examples of the α-hydroxyalkylphenone-based photopolymerization initiator include 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propane-1-one (number average molecular weight: 340), poly(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone) (number average molecular weight: 424), and 2-hydroxy-1-{4-〔4-(2-hydroxy-2-methylpropionyl)phenoxy〕phenyl}-2-methylpropanone (number average molecular weight: 342). Any one or more of these may be included, and a plurality of them may be used in combination. Among them, 2-hydroxy-1-{4-〔4-(2-hydroxy-2-methylpropionyl)phenoxy〕phenyl}-2-methylpropanone and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide are preferred; 2-hydroxy-1-{4-〔4-(2-hydroxy-2-methylpropionyl)phenoxy〕phenyl}-2-methylpropanone is more preferred.

[0110] As the α-hydroxyalkylphenone-based photopolymerization initiator, from the viewpoint of anti-inking and low migration, the one having a number average molecular weight of 300 or more is preferred. Alternatively, the number average molecular weight may be 1500 or less.

[0111] In this specification, the number average molecular weight of the photopolymerization initiator is measured by gel permeation chromatography (GPC).

[0112] Examples of the α-aminoalkylphenone-based photopolymerization initiator include 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one (number average molecular weight: 279), 1-([1,1'-biphenylyl]-4-yl)-2-methyl-2-morpholinopropane-1-one (number average molecular weight: 309), 2-benzyl-2-dimethylamino-1-(4-piperidinylphenyl)-butane-1-one (number average molecular weight: 364), and 2-(dimethylamino)-1- (4-Morpholinophenyl)-2-benzyl-1-butanone (number average molecular weight: 366), 2-(dimethylamino)-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butane-1-one (number average molecular weight: 380), "1-(9,9-dibutyl-9H-fluorene-2-yl)-2-methyl-2-morpholinopropane-1-one" (average molecular weight: 434), as long as any one or more of these are included, a plurality of them may be used in combination. As an α-aminoalkylphenone-based photopolymerization initiator, from the viewpoint of ink resistance and low migration, a number average molecular weight of 300 or more is preferred. In addition, the number average molecular weight may be 1500 or less.

[0113] As acylphosphine oxide-based photopolymerization initiators, there can be cited: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc., any one or more of these can be used, and a plurality of them can also be used in combination. Among them, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide is preferred. As acylphosphine oxide-based photopolymerization initiators, from the viewpoint of ink resistance and low migration, those with a number average molecular weight of 300 or more are preferred. In addition, the number average molecular weight can be 1500 or less.

[0114] Among them, as the intramolecular cleavage type photopolymerization initiator (d-1), from the viewpoints of drying property, ink resistance, low migration, etc. of the coating film, an α-hydroxyalkylphenone type photopolymerization initiator is preferred; from the viewpoint of internal curing property of the coating film, an acylphosphine oxide type photopolymerization initiator is preferred, and a combination of an α-hydroxyalkylphenone type photopolymerization initiator and an acylphosphine oxide type photopolymerization initiator is more preferred. When an α-hydroxyalkylphenone type photopolymerization initiator and an acylphosphine oxide type photopolymerization initiator are used in combination, the ratio of the α-hydroxyalkylphenone type photopolymerization initiator to the acylphosphine oxide type photopolymerization initiator can be 10:90 to 90:10 (by mass), and a ratio of 20:80 to 80:20 is preferred.

[0115] Hydrogen abstraction type photopolymerization initiator (d-2)

[0116] Examples of the hydrogen abstraction type photopolymerization initiator (d-2) include benzophenone type photopolymerization initiators, thioxanthone type photopolymerization initiators, ketosulfone type photopolymerization initiators, etc. The hydrogen abstraction type photopolymerization initiator (d-2) may be used alone or in combination of two or more.

[0117] As benzophenone-based photopolymerization initiators, benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3,'4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 3,3'-dimethyl-4-methoxybenzophenone and other benzophenone-based compounds; 4,4'-bis-dimethylaminobenzophenone, 4,4'-bis-diethylaminobenzophenone and other aminobenzophenone-based compounds. In addition, polymer benzophenone derivatives may also be used. As polymer benzophenone derivatives, specifically, GENOPOL BP-2 (manufactured by RAHN AG) and the like may be exemplified. As long as any one or more of these are included, a plurality of them may be used in combination. Among them, polymer benzophenone derivatives are preferred.

[0118] Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-isopropyl thioxanthone, 2-dodecyl thioxanthone, 2-cyclohexyl thioxanthone, 2,4-diethyl thioxanthone, 2,4-dimethyl thioxanthone, 1-phenoxy thioxanthone, 1-methoxycarbonyl thioxanthone, 2-ethoxycarbonyl thioxanthone, 3-(2-methoxyethoxycarbonyl)-thioxanthone, 4-butoxycarbonyl thioxanthone, 3-butoxycarbonyl-7-methyl thioxanthone, 3,4-di-[2-(2-methoxyethoxy)-ethoxycarbonyl]-thioxanthone, 2-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, Thioxanthone, 1-chloro-4-n-propoxythioxanthone, 2-methyl-6-dimethoxymethyl-thioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl)-thioxanthone, 6-ethoxycarbonyl-2-methoxy-thioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, 1-ethoxycarbonyl-3-(1-methyl-1-morpholinoethyl)-thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, thioxanthone-2-carboxylic acid polyethylene glycol ester, polybutylene glycol bis(9-oxo-9H-thioxanthenyl)acetate, and the like may be included at least one of these, and a plurality of these may be used in combination.

[0119] Examples of ketosulfone photopolymerization initiators include 1-[4-(4-benzoylphenylthio)phenyl]-2-methyl-2-(4-methylbenzenesulfonyl)propane-1-one, etc. As long as any one or more of these are included, a plurality of them may be used in combination. Among them, 1-[4-(4-benzoylphenylthio)phenyl]-2-methyl-2-(4-methylbenzenesulfonyl)propane-1-one is preferred.

[0120] Among them, as the hydrogen abstraction type photopolymerization initiator (d-2), benzophenone-based photopolymerization initiators and ketosulfone-based photopolymerization initiators are preferred; more preferably, benzophenone-based photopolymerization initiators and ketosulfone-based photopolymerization initiators are used in combination. When benzophenone-based photopolymerization initiators and ketosulfone-based photopolymerization initiators are used in combination, the ratio of benzophenone-based photopolymerization initiator to ketosulfone-based photopolymerization initiator is 10:90 to 90:10 (by mass), and preferably 20:80 to 80:20.

[0121] In addition, for the hydrogen abstraction type photopolymerization initiator (d-2), from the viewpoint of ink resistance and low migration, the number average molecular weight is preferably 300 or more, more preferably 500 or more. In addition, the number average molecular weight can be 1500 or less. As the hydrogen abstraction type photopolymerization initiator (d-2) having the above characteristics, polytetramethylene glycol bis (9-oxo-9H-thioxanthenyl) acetate, polymer benzophenone derivatives, 1- [4- (4-benzoylphenylthio) phenyl] -2-methyl-2- (4-methylphenylsulfonyl) propane-1-one can be exemplified.

[0122] The photopolymerization initiator in the active energy curable ink composition preferably includes an intramolecular cleavage type photopolymerization initiator (d-1) and a hydrogen abstraction type photopolymerization initiator (d-2). The amount of each photopolymerization initiator in the photopolymerization initiator is not particularly limited. For example, the ratio of the intramolecular cleavage type photopolymerization initiator (d-1): the hydrogen abstraction type photopolymerization initiator (d-2) can be 10:90 to 90:10 (by mass), preferably 20:80 to 60:40. If it is within the above range, the effect of the present invention can be more fully obtained.

[0123] As the photopolymerization initiator in the active energy curable ink composition, the use of photopolymerization initiators other than the above-mentioned ones is not excluded. When a photopolymerization initiator other than the above-mentioned photopolymerization initiator is used, the amount added may be, for example, 10% by mass or less, preferably 5% by mass or less, relative to the total content of the photopolymerization initiator used in the active energy curable ink composition.

[0124] Photoinitiator additive (d-3)

[0125] In the active energy curable ink composition of the present invention, a photopolymerization initiator (D) may be further added with a photoinitiator aid (d-3). Examples of the photoinitiator aid include thioxanthone-based photoinitiators and amine-based photoinitiators. Any one or more of these may be included, and a plurality of these may be used in combination. Among these, amine-based photoinitiators are preferred.

[0126] Examples of the thioxanthone-based photoinitiator aid include thioxanthone, 2-isopropyl thioxanthone, 2-dodecyl thioxanthone, 2-cyclohexyl thioxanthone, 2,4-diethyl thioxanthone, 2,4-dimethyl thioxanthone, 1-phenoxy thioxanthone, 1-methoxycarbonyl thioxanthone, 2-ethoxycarbonyl thioxanthone, 3-(2-methoxyethoxycarbonyl)-thioxanthone, 4-butoxycarbonyl thioxanthone, 3-butoxycarbonyl-7-methyl thioxanthone, 3,4-di-[2-(2-methoxyethoxy)-ethoxycarbonyl]-thioxanthone, 2-chlorothioxanthone, 1-ethoxycarbonyl-3-ethoxythioxanthone. Ketone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-chloro-4-n-propoxythioxanthone, 2-methyl-6-dimethoxymethyl-thioxanthone, 2-methyl-6-(1,1-dimethoxybenzyl)-thioxanthone, 6-ethoxycarbonyl-2-methoxy-thioxanthone, 6-ethoxycarbonyl-2-methylthioxanthone, 1-ethoxycarbonyl-3-(1-methyl-1-morpholinoethyl)-thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, thioxanthone-2-carboxylic acid polyethylene glycol ester, polybutylene glycol bis(9-oxo-9H-thioxanthenyl) acetate, and the like.

[0127] As the amine-based photoinitiator aid, tertiary amines are preferred, for example, aliphatic amines such as triethanolamine, methyldiethanolamine, and triisopropanolamine; aromatic amines such as 4,4'-diethylaminobenzophenone, ethyl 2-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isopentyl 4-dimethylaminobenzoate, and dimethylaminobenzoate with branched polyols. Among them, aromatic amines are preferred, and dimethylaminobenzoate with branched polyols is more preferred.

[0128] As the photoinitiator aid (d-3), from the viewpoint of anti-fogging and low migration, thioxanthone-based photoinitiator aids include polytetramethylene glycol bis(9-oxo-9H-thioxanthenoxy)acetate, 4,4′-diethylaminobenzophenone, and dimethylaminobenzoate of branched polyols.

[0129] The content of the photopolymerization initiator auxiliary (d-3) can be in the range of 0.01 to 50% by mass, preferably in the range of 0.1 to 40% by mass, and the lower limit is more preferably 1% by mass or more, particularly preferably 10% by mass or more.

[0130] As the photopolymerization initiator (D), it is more preferred to use an α-hydroxyalkylphenone-based photopolymerization initiator and an acylphosphine oxide-based photopolymerization initiator together as the intramolecular cleavage-type photopolymerization initiator (d-1), and to use a benzophenone-based photopolymerization initiator and a ketosulfone-based photopolymerization initiator as the hydrogen abstraction-type photopolymerization initiator (d-2). Furthermore, it is preferred to include an amine-based photopolymerization aid as the photopolymerization aid (d-3).

[0131] The total content of the intramolecular cleavage type photopolymerization initiator (d-1), the hydrogen abstraction type photopolymerization initiator (d-2) and the photoinitiation aid (d-3) in 100% by mass of the photopolymerization initiator (D) is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, particularly preferably 98% by mass or more, and may also be 100% by mass.

[0132] The total content of the intramolecular cleavage type photopolymerization initiator (d-1) and the hydrogen abstraction type photopolymerization initiator (d-2) in 100% by mass of the photopolymerization initiator (D) is preferably 1 to 99% by mass, more preferably 10 to 90% by mass, further preferably 20 to 90% by mass, and particularly preferably 55 to 75% by mass.

[0133] Other additives

[0134] The active energy ray curable ink composition of the present invention may contain various additives according to the purpose, and examples thereof include various additives such as stabilizers (for example, polymerization inhibitors such as hydroquinone, hydroquinone methyl ether, and methyl hydroquinone), fillers, viscosity modifiers, extender pigments, waxes, and dispersants. These may be used alone or in combination of two or more. The amount of stabilizer contained in the active energy ray curable ink composition is preferably in the range of 0.01 to 2% by mass, and more preferably in the range of 0.05 to 1% by mass, relative to the total amount of the active energy ray curable ink composition.

[0135] A body pigment may be added to the active energy ray-curable ink composition of the present invention. The body pigment is a component used to impart appropriate printability, viscoelasticity and other properties to the active energy ray-curable ink composition, and various substances commonly used in the preparation of the active energy ray-curable ink composition can be used. Examples of such body pigments include: clay, kaolinite (kaolin), barium sulfate, magnesium sulfate, calcium carbonate, silicon oxide (silicon dioxide), bentonite, talc, mica, titanium oxide, and the like. Among the above-mentioned body pigments, silicon dioxide and talc are most preferred. The amount of such body pigment added can be exemplified by about 0.1 to 10% by mass relative to the total amount of the active energy ray-curable ink composition, and is not particularly limited.

[0136] In order to improve the abrasion resistance, anti-blocking property, etc., the active energy ray-curable ink composition of the present invention may be added with wax. Examples of the aforementioned wax include: paraffin wax, carnauba wax, beeswax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, polytetrafluoroethylene wax, amide wax and the like; fatty acids having an atomic carbon number of about 8 to 18 such as coconut oil fatty acid and soybean oil fatty acid, etc. Among the above waxes, polyethylene wax is most preferred. The amount of such wax added may be about 0 to 10% by mass relative to the total amount of the active energy ray-curable ink composition, and is not particularly limited.

[0137] There are various dispersants such as polymer dispersants and low molecular weight dispersants, and they can be selected according to the dispersibility. As the dispersing aid, a pigment derivative can be used.

[0138] The active energy ray-curable ink composition of the present invention can be prepared by mixing a pigment (A), an ethylenically unsaturated compound (C), a photopolymerization initiator (D), and, as required, a stabilizer (e.g., a polymerization inhibitor such as hydroquinone, hydroquinone methyl ether, methyl hydroquinone), a filler, a viscosity modifier, a body pigment, a wax, and a dispersant in an allyl polymer (B). The active energy ray-curable ink composition of the present invention is cured by irradiating light. The light used for curing is generally ultraviolet light.

[0139] The curing device and curing conditions used in the curing reaction of the active energy ray-curable ink composition are not particularly limited, and any method used in a general photocuring reaction may be used.

[0140] The use of the active energy ray-curable ink composition of the present invention is not particularly limited. For example, it can be used in printing inks such as photocurable lithographic inks, screen printing inks, gravure printing inks, etc. Alternatively, it can be used in coatings for paper, plastics, metals, woodworking, etc., and if exemplified, it is overprint varnish), adhesives, photoresists, and other technical fields. Among them, in addition to toys and various food packaging materials that emphasize safety and hygiene, it can also be widely expanded to packaging and filling uses for sanitary products / cosmetics / pharmaceuticals, etc.

[0141] For example, a conventional method for preparing an active energy ray-curable ink composition is as follows. An acrylic polymer (B) and a stabilizer are dissolved in an ethylenically unsaturated compound (C) at a temperature of 60° C. to 100° C. while stirring to prepare a varnish. In the varnish, a pigment (A), a photopolymerization initiator (D), and other additives are stirred and mixed with a butterfly mixer, and then kneaded with a three-roll mill or the like to obtain an ink composition.

[0142] (Example)

[0143] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0144] Determination of weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of allyl polymers

[0145] The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were measured using GPC. These are values ​​of weight average molecular weight converted to standard polystyrene.

[0146] Column: Shodex KF-806L, KF-804, KF-803, KF-802, KF-801 connected in series

[0147] Flow rate: 1.0mL / min

[0148] Temperature: 40℃

[0149] Detection: RID-6A

[0150] Sample: 20 mg of the sample was dissolved in 10 mL of tetrahydrofuran to prepare a sample for measurement.

[0151] Preparation Example 1 Synthesis of 1,2-cyclohexanedicarboxylic acid diallyl ester polymer

[0152] Diallyl 1,2-cyclohexanedicarboxylate is produced by the esterification reaction of cyclohexanedicarboxylic anhydride and allyl alcohol.

[0153] 2400 g of 1,2-cyclohexanedicarboxylic acid diallyl ester and 60 g of benzoyl peroxide were added to a 3 L separable flask, and heated and stirred at 80°C. After reacting for 2.5 hours, the mixture was cooled to 30°C. After cooling, methanol was added to the flask to precipitate the polymer. The obtained polymer was dried under reduced pressure at 40°C for 16 hours (yield: 408 g, yield: 17%, Mw=32,000, Mw / Mn=2.8). The obtained polymer was referred to as polymer 1 and used in the following manner.

[0154] Examples 1 to 7, Comparative Example 1

[0155] Active energy ray-curable ink compositions having the compositions shown in Tables 3 and 4 below were prepared, and the properties of the active energy ray-curable ink compositions were evaluated.

[0156] 1) Preparation of active energy ray-curable resin composition

[0157] Active energy ray-curable resin compositions (compositions A to C) having the respective compositions shown in Table 1 were prepared.

[0158] [Table 1]

[0159]

[0160] ※The numbers in the table indicate parts by mass.

[0161] ※1; Diallyl phthalate resin (ortho-isomer)

[0162] ※2; Diallyl phthalate resin (isomer (meta orientation))

[0163] ※3; PPTTA: Alkoxy pentaerythritol tetraacrylate EBECRYL40 (manufactured by DAICEL-ALLNEX LTD.)

[0164] ※4; MHQ: Methylhydroquinone (manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0165] 2) Preparation of photopolymerization initiator mixture

[0166] The photopolymerization initiator mixture (mixture 1) described in Table 2 was prepared by heating and stirring.

[0167] [Table 2]

[0168]

[0169] ※The numbers in the table indicate parts by mass.

[0170] ※1; Omnirad 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; number average molecular weight: 418) manufactured by IGM Resins BV

[0171] ※2; GENOPOL BP-2 (polymer benzophenone derivative; number average molecular weight: 980) manufactured by RAHN AG

[0172] ※3; GENOPOL AB-2 (dimethylaminobenzoate with branched polyol; number average molecular weight: 900) manufactured by RAHNAG

[0173] ※4; ESACURE 1001M (1-[4-(4-benzoylphenylthio)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one; number average molecular weight: 515) manufactured by IGM Resins BV

[0174] ※5; ESACURE KIP 160 (2-hydroxy-1-{4-〔4-(2-hydroxy-2-methylpropionyl)phenoxy〕phenyl}-2-methylpropanone; number average molecular weight: 342) manufactured by IGM Resins BV

[0175] 3) Preparation of Active Energy Ray-Curable Ink Compositions 1 to 8 (Examples 1 to 7, Comparative Example 1)

[0176] The compositions A to C prepared in 1) and the components listed in Tables 3 and 4 were ground with a three-roll mill to prepare active energy ray-curable ink compositions 1 to 8, and the ink properties were evaluated.

[0177] [Table 3]

[0178]

[0179] ※The numbers in the table indicate parts by mass.

[0180] [Table 4]

[0181]

[0182] ※The numbers in the table indicate parts by mass.

[0183] ※1; Composition A prepared in 1)

[0184] ※2: Polyester acrylate oligomer EBECRYL LEO 10801 (manufactured by DAICEL-ALLNEX LTD.)

[0185] ※3; PPTTA: Alkoxy pentaerythritol tetraacrylate EBECRYL40 (manufactured by DAICEL-ALLNEX LTD.)

[0186] ※4; Solsperse 39000 (manufactured by Japan Lubrizol Corporation)

[0187] ※5; The mixture of photopolymerization initiators prepared in 2) 1

[0188] ※6: Ink pigment RAVEN 1060 ULTRAPOWDER (manufactured by Birla Carbon)

[0189] ※7: Blue pigment FASTOGEN BLUE FA5375 (manufactured by Sun Chemical)

[0190] ※8: Red pigment SYMULER BRILLIANT CARMINE 6B350K (manufactured by SunChemical)

[0191] ※9; Talc: NICRON 674 (manufactured by Imerys)

[0192] ※10; Silica; CAB-O-SIL M7D (manufactured by Cabot Corporation)

[0193] ※11; Polyethylene wax: S-394-N1 (manufactured by Shamrock)

[0194] ※12; Inhibitor FLORSTAB UV-1 (manufactured by KROMACHEM LTD.)

[0195] ※13; Composition B prepared in 1)

[0196] ※14; Composition C prepared in 1)

[0197] 4) Drying test

[0198] On a single-sided coated paper (made by OJIPAPER CO., LTD.), each of the above compositions 1 to 8 was coated on the surface of the single-sided coated paper using an RI tester to form a coating film. Using a high-pressure mercury lamp with a power of 120W / cm (lamp distance 11cm), the single-sided coated paper coated with each composition was placed on a conveyor belt at a conveyor belt speed of 50m / min and passed through multiple times to cure until the coating film was non-sticky. It should be noted that the UV curing device used a conveyor belt type ultraviolet curing device made by Eye Graphics Co., Ltd. The fewer the number of passes, the better the drying property. The evaluation results are shown in Tables 5 and 6.

[0199] 5) Ink flying test

[0200] The single-sided coated paper was placed under the rubber roller of an ink viscosity meter (manufactured by TOYO SEIKI-SEISAKU-SHO, LTD.), and the roller was rotated at 400 rpm for 1 minute and 1200 rpm for 2 minutes while the ink was applied to the roller. The stains of the ink scattered on the paper surface of the single-sided coated paper were visually confirmed and evaluated according to the following criteria. The evaluation results are shown in Tables 5 and 6.

[0201] Evaluation criteria: No stains on the paper: ○, Slight stains on the paper: △, Many stains on the paper: ×

[0202] [Table 5]

[0203] Example 1 Example 2 Example 3 Comparative Example 1 Composition Composition 1 Composition 2 Composition 3 Composition 4 Dryness (UV exposure times) 2 times 3 times 4 times 4 times Ink resistance 〇 〇 〇 ×

[0204] [Table 6]

[0205] Example 4 Example 5 Example 6 Example 7 Composition Composition 5 Composition 6 Composition 7 Composition 8 Dryness (UV exposure times) 2 times 3 times 2 times 3 times Ink resistance 〇 〇 〇 〇

[0206] The results in Table 5 and Table 6 demonstrate that Examples 1 to 7 have better or equivalent performance than the conventional formulations in terms of drying properties and are also excellent in terms of ink flying resistance.

Claims

1. An active energy ray-curable ink composition, characterized in that: It contains a pigment (A), an allyl polymer (B) obtained by polymerizing an allyl compound represented by the general formula (I), an ethylenically unsaturated compound (C), and a photopolymerization initiator (D). The content of the photopolymerization initiator (D) in the active energy ray-curable ink composition is 5.0% by mass or more, R 1 and R 2 Represent H or CH3, X is an a-valent alicyclic hydrocarbon group or an a-valent aromatic hydrocarbon group, and a represents 2 or 3.

2. The active energy ray-curable ink composition according to claim 1, wherein The photopolymerization initiator (D) includes an intramolecular cleavage type photopolymerization initiator (d-1) and a hydrogen abstraction type photopolymerization initiator (d-2).

3. The active energy ray-curable ink composition according to claim 2, wherein The intramolecular cleavage type photopolymerization initiator (d-1) is at least one selected from the group consisting of α-hydroxyalkylphenone-based photopolymerization initiators, α-aminoalkylphenone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators. The hydrogen abstraction type photopolymerization initiator (d-2) is at least one selected from the group consisting of benzophenone-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and ketosulfone-based photopolymerization initiators. 4 . The active energy ray-curable ink composition according to claim 1 , further comprising a photoinitiator auxiliary (d-3).

5. The active energy ray-curable ink composition according to claim 1 or 2, wherein X in the general formula (I) has any of the following cyclic skeletons, 6. The active energy ray-curable ink composition according to claim 1 or 2, wherein X in the general formula (I) is an aromatic hydrocarbon group having 6 to 20 carbon atoms.

7. The active energy ray-curable ink composition according to claim 1 or 2, wherein X in the general formula (I) has the following cyclic skeleton,

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