Actinic radiation curable ink composition for inkjet printing

Abstract

To provide an active ray-curable ink composition for inkjet printing that is capable of reducing a gloss difference between a low printing rate part and a high printing rate part and excels not only in curability but also in recoating properties when applying a varnish composition to the obtained coating film.SOLUTION: An active ray-curable ink composition for inkjet printing contains a polymerizable compound, a polymerization initiator, and a gelling agent. The wetting index of a cured coating film formed by inkjet printing is 40 mN / m or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an actinic ray-curable ink composition for inkjet printing. More specifically, the present invention relates to an actinic ray-curable ink composition for inkjet printing that can reduce the difference in gloss between a low coverage area and a high coverage area, and that not only has excellent curability but also excellent recoatability when a varnish composition is applied to the resulting coating film. [Background technology]

[0002] Conventionally, printed matter using ultraviolet-curable inkjet ink has a large difference in gloss between low and high coverage areas, especially in single-pass applications. Techniques for reducing the gloss difference include using extender pigments (silica, alumina) with a particle size of 1 μm or more, and using gelling agents such as fatty acid amides to produce low-gloss printed matter (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-40760 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method using extender pigments, ejection stability tends to deteriorate when extender pigments with relatively large particle diameters are used in high-resolution inkjet printers. Also, in the method described in Patent Document 1, the gelling agent tends to float on the printed surface, which can easily cause pinholes and repelling when a varnish is applied in post-processing.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and has an object to provide an actinic ray-curable ink composition for inkjet printing that can reduce the difference in gloss between low printing rate areas and high printing rate areas, and that not only has excellent curability but also excellent recoating properties when a varnish composition is applied to the resulting coating film. [Means for solving the problem]

[0006] The present invention, which solves the above problems, mainly comprises the following configuration.

[0007] (1) An actinic ray-curable ink composition for inkjet printing, comprising a polymerizable compound, a polymerization initiator, and a gelling agent, and forming a cured coating film by inkjet printing with a wetting index of 40 mN / m or more.

[0008] With this configuration, the actinic radiation-curable ink composition for inkjet printing has excellent curability, and the resulting coating film has a reduced difference in gloss between low and high coverage areas, and also has excellent recoatability when applying a varnish composition.

[0009] (2) The actinic ray-curable ink composition for inkjet printing according to (1), wherein the gelling agent contains at least one of a fatty acid ester containing a C12 to C18 hydrocarbon chain and a fatty acid amide containing a C12 to C18 hydrocarbon chain, and the molecule contains two C12 to C18 hydrocarbon chains.

[0010] According to this configuration, the difference in gloss between the low printing rate area and the high printing rate area of ​​the obtained coating film is more likely to be reduced.

[0011] (3) The actinic ray-curable ink composition for inkjet printing according to (1) or (2), wherein the content of the gelling agent is 2% by mass or more.

[0012] According to this configuration, the difference in gloss between the low printing rate area and the high printing rate area of ​​the obtained coating film is more likely to be reduced. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an actinic ray-curable ink composition for inkjet printing that can reduce the difference in gloss between low printing rate areas and high printing rate areas, and that not only has excellent curability but also excellent recoating properties when a varnish composition is applied to the resulting coating film. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Actinic Radiation Curable Ink Composition for Inkjet Printing> An actinic radiation-curable ink composition for inkjet printing (hereinafter also referred to as ink composition) according to one embodiment of the present invention contains a polymerizable compound, a polymerization initiator, and a gelling agent. The cured coating film formed by inkjet printing has a wetting index of 40 mN / m or more. Each of these components will be described below.

[0015] (colorant) The ink composition of this embodiment may contain a coloring material (pigment). There are no particular limitations on the pigment. Examples of the pigment include various organic pigments and inorganic pigments.

[0016] Examples of organic pigments include dye lake pigments, azo-based, benzimidazolone-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indigo-based, thioindigo-based, perylene-based, perinone-based, diketopyrrolopyrrole-based, isoindolinone-based, nitro-based, nitroso-based, flavanthrone-based, quinophthalone-based, pyranthrone-based, and indanthrone-based pigments.

[0017] Inorganic pigments include colored pigments (including achromatic colored pigments such as white and black) such as titanium oxide, red iron oxide, antimony red, cadmium yellow, cobalt blue, ultramarine, Prussian blue, iron black, chromium oxide green, carbon black, and graphite, as well as extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc.

[0018] Specific examples of pigments for each representative hue of the ink composition of this embodiment are as follows: Yellow pigments include CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, and 213, and preferably CI Pigment Yellow 150, 155, 180, and 213.

[0019] Examples of magenta pigments include CI Pigment Red 5, 7, 12, 19, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57, 57:1, 63:1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, and CI Pigment Violet 19, and preferred examples include CI Pigment Red 122, 202, and Pigment Violet 19.

[0020] Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 22, 27, 29, and 60, and preferably CI Pigment Blue 15:4.

[0021] The black pigment is carbon black (CI Pigment Black 7) or the like.

[0022] The content of the pigment is not particularly limited. For example, the content of the pigment in the ink composition is preferably 0.5% by mass or more, and more preferably 2% by mass or more. Furthermore, the content of the pigment in the ink composition is preferably 20% by mass or less, and more preferably 10% by mass or less. When the content of the pigment is within the above range, the ink composition has excellent color reproducibility.

[0023] The ink composition of this embodiment may contain a pigment dispersant. The pigment dispersant is not particularly limited. Examples of the pigment dispersant include carbodiimide-based dispersants, polyester amine-based dispersants, fatty acid amine-based dispersants, modified polyacrylate-based dispersants, modified polyurethane-based dispersants, multi-chain polymeric nonionic dispersants, and polymeric ionic surfactants.

[0024] When a pigment dispersant is added, the content of the pigment dispersant is preferably 1.0 to 100% by mass, and more preferably 5.0 to 60.0% by mass, relative to the pigment, in order to improve the dispersibility of the pigment and the storage stability of the ink composition.

[0025] The ink composition of this embodiment can reduce the difference in gloss between low coverage areas and high coverage areas in the resulting printed matter even when it does not contain an extender pigment, and therefore an extender pigment is not essential and need not be included.

[0026] When an extender pigment is contained, the extender pigment is not particularly limited, and examples of the extender pigment include clay, talc, mica, kaolinite (kaolin), barium sulfate, magnesium sulfate, calcium carbonate, silicon oxide, aluminum oxide, bentonite, ground calcium carbonate, barium carbonate, zirconia, and alumina.

[0027] If the particle size of the extender pigment is large, there is a risk that the gloss difference in the resulting printed matter will be large, so the average particle size of the extender pigment is preferably 0.001 to 0.2 μm, and more preferably 0.01 to 0.1 μm.

[0028] When a body pigment is included, the content of the body pigment is not particularly limited. For example, the content of the body pigment in the ink composition is preferably more than 0% by mass, and more preferably 1% by mass or more. Furthermore, the body pigment may be included to an extent that does not impair ink ejection performance.

[0029] (polymerizable compound) The polymerizable compound may be any known polymerizable compound used in actinic radiation-curable inkjet ink compositions. For example, the polymerizable compound may be a monomer or oligomer having a photopolymerizable unsaturated bond.

[0030] Examples of the monomer having one photopolymerizable unsaturated bond include alkyl methacrylates or acrylates such as methyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; aralkyl methacrylates or acrylates such as benzyl methacrylate and benzyl acrylate; alkoxyalkyl methacrylates or acrylates such as butoxyethyl methacrylate and butoxyethyl acrylate; and aminoalkyl methacrylates such as N,N-dimethylaminoethyl methacrylate and N,N-dimethylaminoethyl acrylate. Methacrylates or acrylates; methacrylic acid esters or acrylic acid esters of polyalkylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, triethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, etc.; methacrylic acid esters or acrylic acid esters of polyalkylene glycol monoaryl ethers such as hexaethylene glycol monophenyl ether; isobornyl methacrylate or acrylate; glycerol methacrylate or acrylate; 2-hydroxyethyl methacrylate or acrylate, etc.

[0031] Monomers having two or more photopolymerizable unsaturated bonds include bisphenol A dimethacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, diethylene glycol dimethacrylate, glycerol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, and dipentaerythritol tetramethacrylate. Examples of such acrylates include erythritol pentamethacrylate, bisphenol A diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, diethylene glycol diacrylate, glycerol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol pentaacrylate.

[0032] The oligomer having a photopolymerizable unsaturated bond is an oligomer obtained by appropriately polymerizing the above-mentioned monomers.

[0033] The content of the photopolymerizable compound is not particularly limited. For example, the content of the photopolymerizable compound can be appropriately determined taking into consideration the physical properties of the cured coating film.

[0034] (Polymerization initiator) The polymerization initiator is not particularly limited. Examples of the polymerization initiator include a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, a triazine-based photopolymerization initiator, and an acylphosphine oxide-based photopolymerization initiator.

[0035] The content of the polymerization initiator is not particularly limited. For example, the content of the polymerization initiator in the ink composition is preferably 3% by mass or more, and more preferably 4% by mass or more. The content of the polymerization initiator in the ink composition is preferably 15% by mass or less, and more preferably 10% by mass or less. When the content of the polymerization initiator is within the above range, the ink composition is likely to have sufficient external curability and internal curability.

[0036] (gelling agent) The gelling agent is not particularly limited. For example, the gelling agent preferably contains at least one of a fatty acid ester containing a C12 to C18 hydrocarbon chain and a fatty acid amide containing a C12 to C18 hydrocarbon chain.

[0037] The fatty acid ester having a C12 to C18 hydrocarbon chain is not particularly limited. Examples of fatty acid esters having a C12 to C18 hydrocarbon chain include ester-based hydrocarbons such as glycol distearate, isopropyl myristate, isopropyl palmitate, octyldodecyl myristate, octyl palmitate, isooctyl palmitate, octyl stearate, isooctyl stearate, butyl stearate, myristyl myristate, stearyl stearate, isopropyl isostearate, 2-hexyldecyl isostearate, propylene glycol isostearate, octyl isopalmitate, and polyglyceryl monoisostearate; and sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monoisostearate, and sorbitan tristearate.

[0038] The fatty acid amide containing a hydrocarbon chain of C12 to C18 is not particularly limited, and examples thereof include n-stearyl oleamide, stearamide, and ricinoleamide.

[0039] Among the above, it is preferable that the gelling agent contains two or more C12 to C18 hydrocarbon chains, which makes it easier to reduce the difference in gloss between low and high printing rate areas of the resulting coating film.

[0040] The melting point of the gelling agent is preferably 36° C. or higher, and more preferably 67° C. or lower. When the melting point is within the above range, the ink composition exhibits excellent ejection stability when a printed matter is produced using, for example, an inkjet printing device having a print head adjusted to 35 to 60° C.

[0041] The content of the gelling agent is preferably 2% by mass or more, and more preferably 5% by mass or more. Furthermore, the content of the gelling agent is preferably 15% by mass or less, and more preferably 12% by mass or less. By keeping the content of the gelling agent within the above range, the ink composition tends to reduce the difference in gloss between low and high coverage areas in the resulting printed matter.

[0042] (optional ingredient) In addition to the above components, the ink composition of this embodiment may also contain the following components as appropriate.

[0043] Sensitizers The sensitizer is not particularly limited. For example, the sensitizer is preferably an anthracene-based sensitizer, a thioxanthone-based sensitizer, or the like, and more preferably a thioxanthone-based sensitizer. Specific examples of the sensitizer include anthracene-based sensitizers such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene, and thioxanthone-based sensitizers such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. Representative examples of commercially available anthracene-based sensitizers include DBA and DEA (manufactured by Kawasaki Chemical Industries, Ltd.), and thioxanthone-based sensitizers include DETX and ITX (manufactured by Lambson Chemical).

[0044] When a sensitizer is contained, the content of the sensitizer is not particularly limited. For example, the content of the sensitizer in the ink composition is preferably 0.5% by mass or more, and more preferably 0.8% by mass or more. Furthermore, the content of the sensitizer in the ink composition is preferably 3% by mass or less, and more preferably 2% by mass or less. When the content of the sensitizer is within the above range, there is an advantage that color change over time of the cured coating film of the ink composition can be suppressed.

[0045] Polymerization inhibitor The polymerization inhibitor is not particularly limited, and examples thereof include phenolic compounds such as butylhydroxytoluene, tocopherol acetate, nitrosamine, benzotriazole, and hindered amine.

[0046] When a polymerization inhibitor is contained, the content of the polymerization inhibitor is not particularly limited. For example, the content of the polymerization inhibitor is preferably 0.5 parts by mass or more, and more preferably 0.8 parts by mass or more, relative to 100 parts by mass of the polymerizable component. Furthermore, the content of the polymerization inhibitor is preferably 2.0 parts by mass or less, and more preferably 1.2 parts by mass or less, relative to 100 parts by mass of the polymerizable component. By keeping the content of the polymerization inhibitor within the above range, the ink composition can be prevented from undergoing a polymerization reaction during storage, thereby preventing the ink composition from becoming thicker.

[0047] UV absorber Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, hydroxyphenyltriazine-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and nickel complex salt-based ultraviolet absorbers.

[0048] When an ultraviolet absorber is contained, the content of the ultraviolet absorber can be adjusted appropriately.

[0049] Antioxidants The antioxidant may be a phenol-based antioxidant, an amine-based antioxidant, a sulfur-based antioxidant, a phosphorus-based antioxidant, or the like.

[0050] When an antioxidant is contained, the content of the antioxidant can be adjusted appropriately.

[0051] Leveling agent The leveling agent may be a nonionic surfactant, a cationic surfactant, an anionic surfactant, a betaine surfactant, or the like.

[0052] When a leveling agent is included, the content of the leveling agent is not particularly limited. For example, the content of the leveling agent in the ink composition is preferably 0.005% by mass or more, and more preferably 0.01% by mass or more, in order to improve the ejection stability of the ink composition from the inkjet head. Furthermore, the content of the leveling agent in the ink composition is preferably 1.5% by mass or less, and more preferably 1% by mass or less.

[0053] The ink composition of this embodiment forms a cured coating film by inkjet printing with a wetting index of 40 mN / m or more. If the wetting index is less than 40 mN / m, the resulting coating film will have poor recoatability when a varnish composition is applied, and pinholes and cissing are likely to occur. The wetting index can be measured in accordance with JIS K 6768 by using various standard wettability indicators manufactured by Wako Pure Chemical Industries, with a viscosity of 22.7 dyn / cm to 70 dyn / cm, applying the indicator to the surface of the cured coating film with a cotton swab, and determining the level just before the index at which repellency occurs.

[0054] From the viewpoint of improving the ejection stability of the ink composition, the viscosity of the ink composition of this embodiment is preferably 100 mPa·s or less at 45°C, more preferably 50 mPa·s or less, and even more preferably 20 mPa·s or less. Furthermore, the viscosity of the ink composition is preferably 1 mPa·s or more, and more preferably 5 mPa·s or more, at 45°C. The viscosity of the ink composition can be designed to be compatible with each inkjet device. In this embodiment, the viscosity can be measured using an E-type viscometer (RE100L type viscometer, manufactured by Toki Sangyo Co., Ltd.) at 45°C and 20 rpm.

[0055] The ink composition of this embodiment can reduce the gloss difference between low and high coverage areas of the resulting coating film. The gloss difference can be evaluated by measuring the gloss value of a cured coating film at 100% coverage of each ink composition printed on coated paper (OK topcoat) in a 25°C environment using a gloss meter (manufactured by BYK). In this embodiment, the gloss value is preferably 60 or less.

[0056] As described above, according to this embodiment, the ink composition has excellent curability, and the resulting coating film has a reduced difference in gloss between low and high coverage areas.

[0057] The varnish composition is not particularly limited, and an example of the varnish composition is water-based varnish AC Coat V-181 manufactured by Sakata Inx Corporation.

[0058] In addition to the effects of curing and reducing gloss difference, the coating film of the ink composition of this embodiment has a wetting index of 40 mN / m or more, and therefore is less likely to develop pinholes or cissing, even when the varnish composition is applied, and has excellent recoatability.

[0059] <Method for preparing ink composition> The method for preparing the ink composition of this embodiment is not particularly limited. For example, the ink composition can be prepared by dispersing and mixing using a dispersing machine such as a wet circulation mill, a bead mill, a ball mill, a sand mill, an attritor, a roll mill, a DCP mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a high-pressure homogenizer (such as a Microfluidizer, Nanomizer, Ultimizer, Genus PY, or DeBEE2000), or a pearl mill.

[0060] <Method of manufacturing printed matter and printed matter> A method for producing a printed matter according to one embodiment of the present invention includes a step of ejecting the ink composition onto a substrate from an inkjet printing device.

[0061] The substrate is not particularly limited, and examples thereof include plastic substrates, paper, metal foil, glass, wood, and cloth. The plastic substrate is a substrate made of one or more materials selected from the group consisting of polyester polymers (e.g., polyethylene terephthalate (PET), polyethylene naphthalate, etc.), cellulose polymers (e.g., diacetyl cellulose, triacetyl cellulose (TAC), etc.), polycarbonate polymers, polyacrylic polymers (e.g., polymethyl methacrylate, etc.), vinyl chloride polymers, polyolefin polymers (e.g., polyethylene, polypropylene, polyolefin polymers having a cyclic or norbornene structure, ethylene-propylene copolymer polymers, etc.), polyamide polymers (e.g., nylon, aromatic polyamide polymers, etc.), polystyrene polymers (e.g., polystyrene, acrylonitrile-styrene copolymer polymers, etc.), polyimide polymers, polysulfone polymers, polyethersulfone polymers, polyetherketone polymers, polyphenylsulfide polymers, polyvinyl alcohol polymers, polyvinylidene chloride polymers, polyvinyl butyral polymers, polyarylate polymers, polyoxymethylene polymers, polyepoxy polymers, and blends of these polymers.

[0062] An inkjet printing device supplies an ink composition to a print head, ejects the ink composition from the print head onto a substrate to be printed so as to form a coating of an appropriate thickness, and then exposes and cures the ink composition that has landed on the substrate with actinic radiation, such as ultraviolet light, electron beams, or visible light emitted from a light-emitting diode (LED), various lamps, or electrodes.

[0063] The coating film obtained as described above has a reduced difference in gloss between the low printing rate area and the high printing rate area, and also has excellent recoatability when applying a varnish composition. [Example]

[0064] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

[0065] The raw materials and preparation methods used are shown below. (Colorant (pigment)) PY155 Pigment Yellow 155 PR122 Pigment Red 122 PB15:4 Pigment Blue 15:4 P.Bk.7 Pigment Black 7 (pigment dispersant) SS32000 (copolymer containing basic functional groups (amine value: 31.2 mg KOH / g), manufactured by Lubrizol Japan Co., Ltd.) SS56000 (copolymer containing basic functional groups (amine value: 39.0 mg KOH / g), manufactured by Lubrizol Japan Co., Ltd.) (polymerizable compound) CN371NS (amine-modified oligomer, multifunctional monomer, manufactured by Sartomer) ACMO (acryloylmorpholine, acrylamide skeleton-containing monomer (monofunctional), manufactured by KJ Chemicals Co., Ltd.) DMAA (N,N-dimethylacrylamide, acrylamide skeleton-containing monomer (monofunctional), manufactured by KJ Chemicals Co., Ltd.) 4HBA (4-hydroxybutyl acrylate, monofunctional monomer, manufactured by Osaka Organic Chemical Industry Ltd.) V190 (Ethyl carbitol acrylate, monofunctional monomer, manufactured by Osaka Organic Chemical Industry Co., Ltd.) HDDA (1,6-hexanediol diacrylate, a multifunctional monomer manufactured by Osaka Organic Chemical Industry Co., Ltd.) Aronix M-933 (high hydroxyl value pentaerythritol acrylate, multifunctional monomer, manufactured by Toagosei Co., Ltd.) (gelling agent) Exepar MY-M (myristyl myristate, melting point 36-46°C, manufactured by Kao Chemical Co., Ltd.) Exepar SS (stearyl stearate, melting point 56-66°C, manufactured by Kao Chemical Co., Ltd.) Emanon 3201M-V (glycol distearate, melting point 60-65°C, manufactured by Kao Chemical Co., Ltd.) Nikkaamide SO (n-stearyl oleic acid amide, melting point 67°C, manufactured by Mitsubishi Chemical Corporation) Excel P-40 (glycerin fatty acid ester, melting point 56-60°C, manufactured by Kao Chemical Co., Ltd.) Excel S-95 (glycerol monostearate, melting point 65-70°C, manufactured by Kao Chemical Co., Ltd.) Fatty acid amide T (stearic acid amide, melting point 97-102°C, manufactured by Kao Chemical Co., Ltd.) Diamid L200 (erucic acid amide, melting point 80°C, manufactured by Mitsubishi Chemical Corporation) Diamid O-200T (oleic acid amide, melting point 70-75°C, manufactured by Mitsubishi Chemical Corporation) Diamid Y (lauric acid amide, melting point 99°C, manufactured by Mitsubishi Chemical Corporation) (Polymerization initiator) TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by Lambson) TPOL (ethoxy(2,4,6-trimethylbenzoyl)phenylphosphine oxide) BAPO (bis(2,4,6-trimethylbenzoyl)-diphenylphosphine oxide) (sensitizer) DETX (diethylthioxanthone, manufactured by Lambson) (polymerization inhibitor) UV22 (quinone polymerization inhibitor, manufactured by ChromaChem) (Surface conditioner (leveling agent)) BYK-377 (polyether-modified silicone surfactant, manufactured by BYK-Chemie)

[0066] <Examples 1 to 13 and Comparative Examples 1 to 7> According to the formulations in Tables 1 to 2 (the mixing ratios of each material are in mass %), each material was stirred and mixed to obtain the active energy ray-curable inkjet printing ink compositions of Examples 1 to 13 and Comparative Examples 1 to 7. Using the obtained ink compositions, the following evaluations were conducted. The results are shown in Tables 1 to 2.

[0067]

Table 1

[0068]

Table 2

[0069] <LED curability> In an environment of 40 °C, the ink composition was applied to coated paper (OK top coat) with a #4 bar coater. Using a UV-LED light lamp manufactured by Foseon Technology, under the irradiation conditions of a distance of 2 cm between the lamp and the coated surface of the ink and an irradiation time of 1 second per application (UV integrated light quantity of 60 mJ / cm 2 ), it was irradiated until the tack on the surface disappeared, and the number of irradiations was evaluated according to the following evaluation criteria. (Evaluation criteria) ○: The number of irradiations was 1 time. ×: The number of irradiations was 2 times or more.

[0070] <Gloss value> The ink composition was printed at a printing head temperature of 45 °C using a UV inkjet printing evaluation apparatus (600 dpi, droplet volume (5 to 50 pL)) equipped with a Ricoh GEN6 head, and cured with LED in the same manner as above to prepare a coating film. Using a gloss meter (BYK gloss meter), the gloss value of the cured coating film was measured and evaluated according to the following evaluation criteria. (Evaluation criteria) 〇: The gloss value was 60 or less. ×: The gloss value exceeded 60.

[0071] <Recoatability> The ink composition was printed at a print head temperature of 45°C using a UV inkjet printing evaluation device (600 dpi, droplet volume (5-50 pL)) equipped with a Ricoh GEN6 head, and then cured with LED in the same manner as above to produce a coating film. The wetting index of the resulting coating film was measured in accordance with JIS-K6768 and evaluated according to the following evaluation criteria. Note that if the wetting index is 40 mN / m or higher, when Sakata Inx Corporation's water-based varnish (AC Coat V-181) is applied with a bar coater, there is no repellency and it can be determined that the recoatability is good. (Evaluation criteria) ○: The wettability index was 40 mN / m or more. ×: The wettability index was less than 40 mN / m.

[0072] As shown in Tables 1 and 2, the ink compositions of Examples 1 to 13 of the present invention had excellent curability. In addition, the resulting coating films had small gloss differences and excellent recoatability.

Claims

1. The composition includes a polymerizable compound, a polymerization initiator, and a gelling agent, the polymerizable compound includes 4-hydroxybutyl acrylate, the content of the 4-hydroxybutyl acrylate in the ink composition is 1.00 to 14.00% by mass, The wetting index of the cured coating film formed by inkjet printing is 40 mN / m or more, and The gloss value of the cured coating film formed by inkjet printing is 60 or less, the gelling agent comprises at least one of a fatty acid ester containing a hydrocarbon chain of C12 to C18 and a fatty acid amide containing a hydrocarbon chain of C12 to C18; The actinic ray curable ink composition for ink jet printing contains two C12 to C18 hydrocarbon chains in the molecule.

2. The actinic ray-curable ink composition for ink-jet printing according to claim 1 , wherein the content of the gelling agent is 2% by mass or more.

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