Electron beam curable inkjet ink, printed matter using the same, and image forming method

Abstract

To provide an electron beam-curable inkjet ink that can quickly form a printed image having low migration, scratch resistance, and high image quality.SOLUTION: An electron beam-curable inkjet ink contains a polymerizable compound (A) having, in each molecule, a C6-30 long-chain alkyl group, a hydrogen bonding group, and a polymerizable group, a polymerizable compound (B) excluding the component (A), and a colorant (C).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electron beam curable inkjet ink, a printed matter using the same, and an image forming method. [Background technology]

[0002] Inkjet recording using an inkjet printer is a method of printing by ejecting ink droplets from the printer and depositing them on a recording medium such as paper, resin film, etc. This method has rapidly spread in recent years because it is easy to reduce the size and speed, and its application in industrial applications is also progressing.

[0003] UV-curable inkjet inks that are cured by exposure to UV rays are known as a type of inkjet ink. UV-curable inkjet inks are generally compositions containing a polymerizable compound, a photoinitiator, and a colorant. When droplets of UV-curable inkjet ink are landed on the surface of a recording medium and the landed droplets are irradiated with UV rays, the reaction of the polymerizable compound in the ink proceeds, and the droplets are cured to form a cured film on the surface of the recording medium. Compared to solvent-based and water-based inkjet inks, UV-curable inkjet inks have features such as high-speed curing and versatility in substrates, and are therefore expected to be applied to packaging materials.

[0004] However, in the cured film formed by curing the ultraviolet-curable inkjet ink, unreacted photoinitiators, decomposition products of the photoinitiators, unreacted polymerizable compounds, and other low-molecular-weight compounds remain, causing problems of migration and odor. Therefore, when printing on food packaging materials in particular, it is essential to reduce the amount of unreacted photoinitiators and decomposition products of the photoinitiators that tend to emit odors.

[0005] Electron beam curable inkjet inks are inkjet inks that solve the problems of migration and odor while maintaining the excellent high-speed curing and substrate versatility of UV-curable inkjet inks.

[0006] Electron beam curable inkjet inks can cure ink droplets using the high energy of an electron beam without using a photoinitiator, which makes it possible to prevent migration and odors caused by photoinitiators.

[0007] In order to take advantage of these advantages, various studies have been carried out on electron beam curable inkjet inks.

[0008] Patent Document 1 discloses an electron beam curable inkjet ink containing a colorant, dipropylene glycol diacrylate as a polymerizable compound, and 2-(2-vinyloxyethoxy)ethyl acrylate. However, when color printing is performed with this ink, the ink droplets of each color land on a substrate, and the landed ink droplets mix with each other during the time until they are irradiated with an electron beam, resulting in a deterioration in image quality.

[0009] Patent Document 2 discloses an electron beam curable inkjet ink containing a photopolymerizable compound including a trifunctional or higher polyfunctional compound, a linear alkyl aldehyde having 6 to 9 carbon atoms, and a gelling agent, as a technology for solving the problem of mixing of droplets of the deposited electron beam curable inkjet ink. However, when the ink is applied to food packaging materials, the unreacted linear alkyl aldehyde and gelling agent may migrate into the food, and the reduction in migration is insufficient. In addition, the linear alkyl aldehyde inhibits the reactivity of the polymerizable compound, and the scratch resistance of the cured film is also insufficient. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 6477113 [Patent Document 2] JP 2019-104845 A Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above circumstances, and has an object to provide an electron beam curable inkjet ink that has low migration and excellent abrasion resistance and is capable of forming high quality printed images at high speed. [Means for solving the problem]

[0012] That is, the present invention relates to the following [1] to [6]. Note that in this application, "(Numerical value 1) to (Numerical value 2)" indicates that the upper and lower limits are included. [1] The electron beam curable inkjet ink contains: a polymerizable compound (A) having a long-chain alkyl group having from 6 to 30 carbon atoms in the molecule, a hydrogen-bonding group, and a polymerizable group; a polymerizable compound (B) other than component (A); and a colorant (C). [2] The electron beam curable ink-jet ink according to item [1] above, wherein the component (A) is a reaction product of an alcohol compound (a) having from 6 to 30 carbon atoms and an isocyanate compound (b) having a (meth)acrylate group. [3] The electron beam curable inkjet ink according to item [1] or [2] above, wherein the content of the component (A) in the total amount of the electron beam curable inkjet ink is 0.5 to 90% by weight. [4] The electron beam-curable ink-jet ink according to any one of the above items [1] to [3], wherein the solidification initiation temperature is 20°C or higher and lower than 100°C. [5] A printed matter using the electron beam curable inkjet ink according to any one of the above items [1] to [4]. [6] An image forming method comprising the following steps 1 to 3. (Step 1) A step of heating the electron beam curable inkjet ink according to any one of the above items [1] to [4] to a temperature equal to or higher than the ink solidification start temperature. (Step 2) A step of ejecting droplets of the electron beam curable inkjet ink according to any one of the above items [1] to [4] from a nozzle of an ejection head and landing the droplets on a substrate surface. (Step 3) Further irradiate the ink with electron beams to harden it. Effect of the Invention

[0013] The present invention can provide an electron beam curable inkjet ink that has low migration and excellent abrasion resistance and is capable of forming high quality printed images at high speed. [Brief description of the drawings]

[0014] [Figure 1] 1H-NMR chart of Synthesis Example 1 is shown. [Diagram 2] 1 shows a chart of the solidification start temperature measurement in Example 1. [Diagram 3] 1 shows a solidification start temperature measurement chart for Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In this specification, "CI" is an abbreviation for Color Index. In addition, "(meth)acrylate" means "acrylate" and / or "methacrylate". Furthermore, in this specification, "%" and "parts" are all written on a weight basis unless otherwise specified.

[0016] [Electron beam curable inkjet ink] The electron beam-curable inkjet ink of the present invention contains a polymerizable compound (A) (hereinafter also referred to simply as "component (A)") having a long-chain alkyl group having from 6 to 30 carbon atoms in the molecule, a hydrogen-bonding group, and a polymerizable group, a polymerizable compound (B) (hereinafter also referred to simply as "component (B)") other than component (A), and a colorant (C) (hereinafter also referred to simply as "component (C)").

[0017] [Polymerizable compound (A) having a long-chain alkyl group having 6 to 30 carbon atoms in the molecule, a hydrogen-bonding group, and a polymerizable group] Component (A) has 6 to 30 long-chain alkyl groups, hydrogen-bonding groups, and polymerizable groups in the molecule. When the droplets of the electron beam curable inkjet ink of the present invention are ejected from the nozzle of the ejection head and land on the surface of a substrate, the droplets solidify and are less likely to mix with each other due to the inclusion of component (A), so that a high-definition image can be formed. Furthermore, since component (A) has a polymerizable group, it is fixed in the cured film by electron beam irradiation, and low migration can also be achieved.

[0018] It is more preferable that the long-chain alkyl group having 6 to 30 carbon atoms is a straight-chain alkyl group having 12 to 22 carbon atoms. When the alkyl group has less than 6 carbon atoms, the ink droplets are difficult to solidify when they land on the substrate surface, and the droplets are mixed together, resulting in poor image quality. When the alkyl group has more than 30 carbon atoms, the abrasion resistance of the cured film is poor. When the alkyl group has 6 or more carbon atoms, the ink droplets are easily solidified when they land on the substrate surface, so that a high-quality image can be obtained, and when the alkyl group has 30 or less carbon atoms, the abrasion resistance of the cured film is not insufficient. In addition, an alkyl group having 6 or more carbon atoms also has the effect of reducing the viscosity of the ink.

[0019] Examples of the hydrogen-bonding group of component (A) include a hydroxyl group, a urethane group, a urea group, an amide group, a carboxyl group, and an ester group. The presence of the hydrogen-bonding group makes it easier for the ink droplets to solidify when they land on the surface of the substrate. Among the hydrogen-bonding groups, the hydroxyl group, the urethane group, and the amide group are preferred, and the urethane group is more preferred from the viewpoint of imparting toughness to the cured film and adhesion to the substrate.

[0020] The polymerizable group of component (A) is not particularly limited as long as it undergoes a polymerization reaction upon electron beam irradiation. Examples of the polymerizable group include an acrylic group, a methacrylic group, a vinyl group, a vinyl ether group, and an allyl group. From the viewpoint of productivity, an acrylic group or a methacrylic group, which has a fast curing rate, is preferred.

[0021] The method for obtaining component (A) is not particularly limited, and examples thereof include a method of reacting an alcohol compound (a) having 6 to 30 carbon atoms (hereinafter simply referred to as "component (a)") with an isocyanate compound (b) having a (meth)acrylate group (hereinafter simply referred to as "component (b)"), or a method of reacting an isocyanate compound (c) having 6 to 30 carbon atoms (hereinafter simply referred to as "component (c)") with a (meth)acrylate compound (d) having a hydroxyl group (hereinafter simply referred to as "component (d)").

[0022] When reacting component (a) with component (b), the target component (A) can be obtained by mixing component (b) with component (a) so that the amount of isocyanate groups per equivalent of hydroxyl groups is 1.0 to 1.2 equivalents, preferably 1.05 to 1.1 equivalents, and reacting at a reaction temperature of 70 to 90° C. When reacting component (c) with component (d), the target component (A) can be obtained by mixing component (d) with component (c) so that the amount of hydroxyl groups per equivalent of isocyanate is 1.0 to 1.2 equivalents, preferably 1.05 to 1.1 equivalents, and reacting at a reaction temperature of 70 to 90° C.

[0023] Examples of component (a) include hexyl alcohol, octyl alcohol, tridecanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol, 1,2-hexanediol, 1,2-octanediol, 1,2-nonanediol, 1,2-decanediol, 1,2-dodecanediol, 1,2-tetradecanediol, 1,2-hexadecanediol, 1,2-octadecanediol, and 1,2-icosanediol, and preferably those having no branched structure.

[0024] Examples of component (b) include 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko K.K.), 2-isocyanatoethyl acrylate (Karenz AOI manufactured by Showa Denko K.K.), 2-(2-methacryloyloxyethyloxy)ethyl isocyanate (Karenz MOI-EG manufactured by Showa Denko K.K.), and 1,1-(bisacryloyloxymethyl)ethyl isocyanate (Karenz BEI manufactured by Showa Denko K.K.).

[0025] Examples of the component (c) include hexyl isocyanate, heptyl isocyanate, octyl isocyanate, nonyl isocyanate, decyl isocyanate, dodecyl isocyanate, octadecyl isocyanate, hexamethylene diisocyanate, and the like, with octadecyl isocyanate (Millionate O, manufactured by Hodogaya Chemical Co., Ltd.) and hexamethylene diisocyanate (HDI) being particularly preferred.

[0026] Examples of the component (d) include hydroxy C2-C4 alkyl (meth)acrylates such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, dimethylolcyclohexyl mono(meth)acrylate, hydroxycaprolactone (meth)acrylate, hydroxyl-terminated polyalkylene glycol (meth)acrylate, glycerin di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate. From the viewpoint of curability, however, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, hydroxycaprolactone acrylate, glycerin diacrylate, pentaerythritol triacrylate, and dipentaerythritol pentaacrylate are preferred.

[0027] In the electron beam curable inkjet ink of the present invention, component (A) may be used alone or in a mixture of two or more kinds in any ratio. The content of component (A) in the total amount of the electron beam curable inkjet ink of the present invention is preferably 0.5 to 90% by weight, more preferably 1 to 80% by weight, particularly preferably 3 to 50% by weight, and most preferably 5 to 20% by weight. If the content is less than 0.5% by weight, the ink droplets are difficult to solidify when they land on the substrate surface, and the droplets mix with each other, resulting in poor image quality. If the content is more than 90% by weight, the abrasion resistance of the cured film is poor.

[0028] [Polymerizable compound (B) other than component (A)] The electron beam curable inkjet ink of the present invention contains, as component (B), a polymerizable compound other than component (A). Component (B) may be an alkyl (meth)acrylate having 5 to 25 carbon atoms, such as isooctyl (meth)acrylate, isoamyl (meth)acrylate, lauryl (meth)acrylate, isodecyl (meth)acrylate, stearyl (meth)acrylate, cetyl (meth)acrylate, isomyristyl (meth)acrylate, isostearyl (meth)acrylate, or tridecyl (meth)acrylate, benzyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, or phenoxyethyl (meth)acrylate. , (meth)acrylamide, N-hydroxyethyl acrylamide, N,N-dimethyl acrylamide, N,N-diethyl acrylamide, acryloyl morpholine, allyloxymethyl methyl acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, 2-(2-vinyloxyethoxy)ethyl methacrylate, phenyl glycidyl (meth)acrylate, tricyclodecane (meth)acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate Acrylate, dicyclopentanyl (meth)acrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl acrylate, 1-adamantyl methacrylate, polypropylene oxide modified nonylphenyl (meth)acrylate, dicyclopentadieneoxyethyl (meth)acrylate, and other (meth)acrylates having a cyclic skeleton, 4-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, ) acrylate, and other alkyl (meth)acrylates having a hydroxyl group; ethoxydiethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polypropylene oxide-modified nonylphenyl (meth)acrylate and other polyalkylene glycol (meth)acrylates; caprolactone-modified tetrafurfuryl (meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate,Di(meth)acrylates of aliphatic hydrocarbon diols having 5 to 12 carbon atoms, such as 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and tricyclodecanedimethanol di(meth)acrylate, xanthane glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, alkylene oxide modified bisphenol A type di(meth)acrylate, caprolactone modified hydroxypivalic acid neopentyl glycol di(meth)acrylate, trimethylol propane tri(meth)acrylate, trimethylol octane tri(meth)acrylate and other trimethylol carbon number 2 to 10 alkane tri(meth)acrylates, trimethylol propane polyethoxy tri(meth)acrylate acrylate, trimethylolpropane polypropoxy tri(meth)acrylate, trimethylolpropane polyethoxy polypropoxy tri(meth)acrylate and other trimethylol carbon number 2-10 alkane polyalkoxy tri(meth)acrylate, tris[(meth)acryloyloxyethyl]isocyanurate, pentaerythritol tri(meth)acrylate, ethylene oxide modified trimethylolpropane tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate and other alkylene oxide modified trimethylolpropane tri(meth)acrylate trimethylolpropane tri(meth)acrylate pentaerythritol polyethoxy tetra(meth)acrylate, pentaerythritol polypropoxy tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy(meth)acrylate oligomer, aliphatic urethane(meth)acrylate oligomer,(Meth)acrylate compounds such as aromatic urethane (meth)acrylate oligomers and polyester (meth)acrylate oligomers; monofunctional vinyl ether compounds including butyl vinyl ether, butyl propenyl ether, butyl butenyl ether, hexyl vinyl ether, ethylhexyl vinyl ether, phenyl vinyl ether, benzyl vinyl ether, ethyl ethoxy vinyl ether, acetyl ethoxy ethoxy vinyl ether, cyclohexyl vinyl ether, and adamantyl vinyl ether; ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol vinyl ether, butylene divinyl ether, dibutylene glycol divinyl ether, neopentyl glycol divinyl ether, cyclohexanediol divinyl ether, cyclohexane dimethanol divinyl ether, norbornyl dimethanol divinyl ether, isovinyl divinyl ether, divinyl resorcinol, and Examples of such vinyl ether compounds include difunctional vinyl ether compounds including divinyl hydroquinone, trifunctional vinyl ether compounds including glycerin trivinyl ether, glycerin ethylene oxide adduct trivinyl ether (ethylene oxide added mole number: 6), trimethylolpropane trivinyl ether, trivinyl ether ethylene oxide adduct trivinyl ether (ethylene oxide added mole number: 3), pentaerythritol trivinyl ether, ditrimethylolpropane hexavinyl ether, and trifunctional or higher vinyl ether compounds including oxyethylene adducts thereof, aromatic vinyl compounds including styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, vinylnaphthalene, indene, divinylbenzene, and diallyl phthalate, vinyl ester compounds including vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, and divinyl adipate, and allyl compounds including allyl acetate, allyl benzoate, diallyl adipate, diallyl terephthalate, diallyl isophthalate, and diallyl phthalate.

[0029] From the viewpoint of reactivity and solubility of component (A), acryloylmorpholine, allyloxymethyl methyl acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, 2-(2-vinyloxyethoxy)ethyl methacrylate, phenylglycidyl (meth)acrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, polytetramethylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and ethylene oxide-modified trimethylolpropane triacrylate are particularly preferred.

[0030] From the viewpoint of imparting flexibility to the ink after curing, lauryl acrylate, isodecyl acrylate, stearyl acrylate, cetyl acrylate, isomyristyl acrylate, isostearyl acrylate, tridecyl acrylate, polypropylene glycol diacrylate, polyethylene glycol diacrylate, polytetramethylene glycol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, 1,12-dodecanediol diacrylate, aliphatic urethane acrylate oligomers, and aromatic urethane acrylate oligomers are particularly preferred.

[0031] In the electron beam curable inkjet ink of the present invention, component (B) may be used alone or in a mixture of two or more kinds in any ratio. The content of component (B) in the total amount of the electron beam curable inkjet ink of the present invention is preferably 10 to 99.5% by weight, more preferably 20 to 99% by weight, and particularly preferably 50 to 95% by weight.

[0032] Colorant (C) The electron beam curable inkjet ink of the present invention contains a colorant as component (C). As component (C), a dye or a pigment can be used, and from the viewpoint of obtaining an image with good weather resistance, the colorant is preferably a pigment. The pigment can be selected from, for example, a yellow pigment, a red or magenta pigment, a blue or cyan pigment, and a black pigment depending on the color of the image to be formed, and examples of the pigment include inorganic pigments, organic pigments, extender pigments, and hollow particles.

[0033] Examples of the inorganic pigment include carbon black, metal oxides, hydroxides, sulfides, ferrocyanides, and metal chlorides.

[0034] When the ink is a black ink and the pigment is an inorganic pigment, the inorganic pigment contained in the black ink is preferably carbon black such as thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black. Specific examples of carbon black include the Raven series manufactured by Columbia Carbon, the Monarch series, Regal series, and Mogul series manufactured by Cabot Corporation, the ColorBlack series, Printex series, SpecIalBlack series, and Nerox series manufactured by Orion Engineered Carbons, and the MA series, MCF series, No. 25, No. 33, No. 40, No. 47, No. 52, No. 900, and No. 2300 manufactured by Mitsubishi Chemical Corporation. When the ink is a white ink and the pigment is an inorganic pigment, examples of the inorganic pigment contained in the white ink include oxides, nitrides, and oxynitrides of metals such as zinc, silicon, aluminum, titanium, strontium, and zirconium; and inorganic compounds such as various types of glass and silica, and titanium dioxide and zinc oxide are preferred.

[0035] Examples of the organic pigment include various pigments such as azo, disazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perinone, thioindigo, anthraquinone, and quinophthalone, and disazo is preferred.

[0036] Examples of the organic pigment include yellow such as CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 128, 129, 138, 139, 150, 151, 154, 155, 180, 185, 193, 199, 202, and 213; Reds such as 5, 7, 12, 48, 48:1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 168, 177, 178, 179, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 269, 272; Blues such as 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, 80; Violets such as 19, 23, 29, 37, 38, 50; Oranges such as 13, 16, 43, 68, 69, 71, 73; Examples of pigments include green pigments such as Green 7, 36, and 54; and black pigments such as CI Pigment Black 1.

[0037] Examples of the extender pigment include silica, calcium carbonate, talc, clay, barium sulfate, white carbon, etc. The extender pigment is often used in combination with other colorants.

[0038] As the hollow particles, for example, known hollow particles described in U.S. Pat. No. 4,880,465, Japanese Patent No. 3,562,754, Japanese Patent No. 6026234, Japanese Patent No. 5459460, JP-A-2003-268694, Japanese Patent No. 4902216, etc. can be used, and it is particularly preferable to use them as a white pigment.

[0039] The disperse dye may be a known disperse dye or a known oil-soluble dye. As the known disperse dye, CI Dispers-based disperse dyes are preferred. Specific examples thereof include yellows such as CIDispers Yellow 9, 23, 33, 42, 49, 54, 58, 60, 64, 66, 71, 76, 79, 83, 86, 90, 93, 99, 114, 116, 119, 122, 126, 149, 160, 163, 165, 180, 183, 186, 198, 200, 211, 224, 226, 227, 231, and 237; reds such as CIDispers Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, and 283; and CIDispers Orange. Examples of disperse dyes include oranges such as 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, and 97; violets such as CI Dispers Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, and 79:1; and blues such as CI Dispers Blue 27, 56, 60, 79:1, 87, 143, 165, 165:1, 165:2, 181, 185, 197, 202, 225, 257, 266, 267, 281, 341, 353, 354, 358, 364, 365, and 368. As the known solvent dye, CISolvent-based disperse dyes are preferred.

[0040] The average particle size of component (C) is preferably 30 nm to 300 nm, and more preferably 50 nm to 250 nm. In this specification, the average particle size refers to the average particle size of particles measured by a laser light scattering method.

[0041] In the electron beam curable inkjet ink of the present invention, component (C) may be used alone or in a mixture of two or more kinds in any ratio. The content of component (C) in the total amount of the electron beam curable inkjet ink of the present invention is preferably 0.1 to 40% by weight, more preferably 0.5 to 20% by weight, particularly preferably 1 to 10% by weight, and most preferably 2 to 7% by weight.

[0042] [Optional ingredients] The electron beam curable inkjet ink of the present invention may contain, as appropriate, various additives such as a surface tension adjuster, a pigment dispersant, an ultraviolet absorber, an antifoaming agent, an antioxidant, a light stabilizer (for example, a hindered amine compound, etc.), a silane coupling agent, a metal adhesion imparting agent, and an organic solvent as optional components.

[0043] (Surface tension adjuster) The electron beam curable inkjet ink of the present invention may further contain a surfactant as a surface tension adjuster. Examples of the surfactant include anionic, nonionic, silicone, and fluorine-based surfactants. Among these, a surfactant selected from the group consisting of nonionic and silicone surfactants is preferred.

[0044] Examples of the anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acylamino acids or salts thereof, N-acylmethyltaurines, alkyl sulfates, polyoxyalkyl ether sulfates, alkyl sulfates, polyoxyethylene alkyl ether phosphates, rosin acid soaps, castor oil sulfates, lauryl alcohol sulfates, alkylphenol phosphates, alkyl phosphates, alkylarylsulfonates, diethylsulfosuccinates, diethylhexylsulfosuccinates, and dioctylsulfosuccinates.

[0045] Examples of the nonionic surfactants include ether surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and polyoxyethylene distyrenated phenyl ether (for example, Emulgen A-60, A-90, and A-500 manufactured by Kao Corporation); ester surfactants such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; and acetylene glycol (or acetylene alcohol) surfactants such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyne-3-ol (for example, Surfynol manufactured by Evonik Japan Co., Ltd.). 104, 104PG50, 82, 420, 440, 465, 485, Olfine STG, etc.); polyglycol ethers, etc.

[0046] Examples of silicone surfactants include polyether-modified siloxanes and polyether-modified polydimethylsiloxanes. Examples of such surfactants include Dynol 960 and 980 manufactured by Air Products Co., Ltd.; Silface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG009, SAG010, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 manufactured by Nissin Chemical Co., Ltd.; and BYK Additives & and BYK-306, 307, 333, 347, 348, BYK-UV3500, UV-3510, UV-3530, UV3570, 345, 347, 348, 349, 3455, LP-X23288, LP-X23289, and LP-X23347 manufactured by Evonic Instruments; and TEGO Twin 4000, TEGO Wet KL 245, 250, 260, 265, 270, 280, TEGO Rad 2010, 2011, 2100, 2200N, 2250, 2300, 2500, 2600, and 2700 manufactured by Evonic Tego Chemie.

[0047] Examples of fluorine-based surfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains, etc. Specific examples of commercially available products include Capstone FS-30 and FS-31 (manufactured by Chemours), etc.

[0048] Among the above surfactants, surfactants containing a polymerizable group are preferred from the viewpoint of migration, and examples thereof include BYK-UV3500, BYK-UV3510, BYK-UV3530, BYK-UV3570, TEGO Rad 2010, 2011, 2100, 2200N, 2250, 2300, 2500, 2600, and 2700.

[0049] (Pigment dispersant) The electron beam curable inkjet ink of the present invention can use a pigment dispersant. Examples of pigment dispersants include polyurethane skeletons, polyacrylic skeletons, polyester skeletons, polyamide skeletons, polyimide skeletons, and polyurea skeletons. Specific examples include Solsperse 24000GR, 32000, 33000, 35000, 39000, 41000, 53000, and J180 (manufactured by Lubrizol), and Ajisper PB821, 822, 824, 827, and 711 (manufactured by Ajinomoto Fine-Techno Co., Ltd.).

[0050] (UV absorber) The electron beam curable inkjet ink of the present invention may contain an ultraviolet absorbing agent to improve weather resistance. Examples of ultraviolet absorbing agents include benzophenone-based ultraviolet absorbing agents, benzotriazole-based ultraviolet absorbing agents, salicylate-based ultraviolet absorbing agents, hydroxyphenyltriazine-based ultraviolet absorbing agents, cyanoacrylate-based ultraviolet absorbing agents, and nickel complex salt-based ultraviolet absorbing agents. Among them, 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole (trade name: RUVA-93, manufactured by Otsuka Chemical Co., Ltd.) containing a polymerizable group is preferable because of its low migration risk.

[0051] (Antioxidants) Specific examples of the antioxidant include BHT, 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylene bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N-hexyl Examples of the monomer include samethylene bis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, octylated diphenylamine, 2,4-bis[(octylthio)methyl-O-cresol, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], dibutylhydroxytoluene, and 4-allyl-2,6-di-t-butylphenol. However, 4-allyl-2,6-di-t-butylphenol (trade name: TRIAM-100, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) containing a polymerizable group is preferable because it has a low migration risk.

[0052] (Light stabilizer) Specific examples of the light stabilizer include 1,2,2,6,6-pentamethyl-4-piperidyl alcohol, 2,2,6,6-tetramethyl-4-piperidyl alcohol, 1,2,2,6,6-pentamethyl-4-piperidyl (meth)acrylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6 -Mixed esters of pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, decanedioic acid bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1-undecaneoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,2,6,6-pentamethyl-4-piperidinyl-methacrylate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)[[3,5-bis(1,1-dimethyl) ethyl)-4-hydroxyphenyl]methyl]butylmalonate, decanedioic acid bis(2,2,6,6-tetramethyl-1(octyloxy)-4-piperidinyl) ester, reaction products of 1,1-dimethylethyl hydroperoxide with octane, N,N',N'',N'''-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine, dibutylamine·1,3,5-triazine·N,N'-bis(2,2,6,Polycondensation product of 6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, poly[[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]], polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, ,2,4,4-Tetramethyl-20-(β-lauryloxycarbonyl)ethyl-7-oxa-3,20-diazadispiro〔5,1,11,2〕heneicosan-21-one, β-alanine, N-(2,2,6,6-tetramethyl-4-piperidinyl)-dodecyl ester / tetradecyl ester, N-acetyl-3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidinyl)pyrrolidine-2,5-dione, 2,2,4,4-tetramethyl-7-oxa-3,20-diazadispiro〔5,1,11,2〕heneicosane -21-one, 2,2,4,4-tetramethyl-21-oxa-3,20-diazadicyclo-[5,1,11,2]-heneicosane-20-propanoic acid dodecyl ester / tetradecyl ester, propanedioic acid, [(4-methoxyphenyl)-methylene]-bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, higher fatty acid esters of 2,2,6,6-tetramethyl-4-piperidinol, 1,3-benzenedicarboxamide, N,N'-bis(2,2,6,6-tetramethyl-4-piperi diphenyl), hindered amine compounds, benzophenone compounds, such as octabenzone, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole, 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate with polyethylene glycol, benzotriazole compounds such as 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, benzoates such as 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, and triazine compounds such as 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]phenol, but 1,2,2,6,6-pentamethyl-4-piperidyl (meth)acrylate (trade name: LA-82, manufactured by Adeka Corporation) containing a polymerizable group is preferred due to its low migration risk.

[0053] (Silane coupling agent) The electron beam curable inkjet ink of the present invention may contain a silane coupling agent to improve adhesion to the substrate. Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, and N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride. , 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane and other silane-based coupling agents; isopropyl(N-ethylaminoethylamino)titanate, isopropyltriisostearoyltitanate, titanium di(dioctylpyrophosphate)oxyacetate, tetraisopropyldi(dioctylphosphite)titanate, neoalkoxytri(pN-(β-aminoethyl)aminophenyl)titanate and other titanium-based coupling agents;Examples of the coupling agent include zirconium or aluminum coupling agents such as Zr-acetylacetonate, Zr-methacrylate, Zr-propionate, neoalkoxyzirconate, neoalkoxytrisneodecanoylzirconate, neoalkoxytris(dodecanoyl)benzenesulfonylzirconate, neoalkoxytris(ethylenediaminoethyl)zirconate, neoalkoxytris(m-aminophenyl)zirconate, ammonium zirconium carbonate, Al-acetylacetonate, Al-methacrylate, and Al-propionate. However, vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.), 3-methacryloxypropylmethyldimethoxysilane (trade name: KBM-502, manufactured by Shin-Etsu Chemical Co., Ltd.), 3-methacryloxypropyltrimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.), 3-methacryloxypropyltriethoxysilane (trade name: KBE-503, manufactured by Shin-Etsu Chemical Co., Ltd.), and 3-acryloxypropyltrimethoxysilane (trade name: KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), which contain a polymerizable group, are preferred because they have a low migration risk;

[0054] (Metal adhesion promoter) The electron beam curable inkjet ink of the present invention may contain a metal adhesion promoter to improve adhesion to metal substrates such as aluminum. Specific examples of metal adhesion promoters include ethylene oxide modified phenoxylated (meth)acrylate phosphate, ethylene oxide modified butoxylated (meth)acrylate phosphate, ethylene oxide modified octyloxylated (meth)acrylate phosphate, ethylene oxide modified di(meth)acrylate phosphate, ethylene oxide modified tri(meth)acrylate phosphate, and caprolactone modified ethylene oxide modified di(meth)acrylate phosphate, with ethylene oxide modified dimethacrylate phosphate (trade name: KAYAMER PM-2, manufactured by Nippon Kayaku Co., Ltd.) and caprolactone modified ethylene oxide modified dimethacrylate phosphate (trade name: KAYAMER PM-21, manufactured by Nippon Kayaku Co., Ltd.) being easily available and having a low migration risk, being preferred.

[0055] (Organic solvent) The electron beam curable inkjet ink of the present invention may contain an organic solvent in order to adjust the storage stability, ejection stability, flying properties of the ink, etc. Examples of the organic solvent include alcohols, ketones, ethers, esters, nitrogen-containing compounds, amides, etc.

[0056] [Method of preparing electron beam curable inkjet ink] The electron beam curable inkjet ink of the present invention can be prepared by a conventionally known method. A suitable preparation method for the electron beam curable inkjet ink of the present invention containing a pigment as a colorant will be described below. A dispersing machine is used to premix component (C), a part of component (B), and any other component (more specifically, a pigment dispersant, etc.) as necessary, and each component is dissolved or dispersed to prepare a primary dispersion. Examples of dispersing machines include a disperser, a container-driven media mill (more specifically, a ball mill, a centrifugal mill, a planetary ball mill, etc.), a high-speed rotary mill (more specifically, a sand mill, etc.), and a media stirring mill (more specifically, a stirring tank type mill, etc.).

[0057] Next, the component (A), the remaining component (B), and the above-mentioned additives, if necessary, are added to the obtained primary dispersion liquid, and mixed uniformly using a stirrer. Examples of the stirrer include a disperser, a three-one motor, a homogenizer, and a magnetic stirrer. In this manner, an electron beam curable inkjet ink can be obtained. The electron beam curable inkjet ink may also be mixed using a mixer such as a line mixer. Furthermore, in order to further refine the particles in the electron beam curable inkjet ink, the electron beam curable inkjet ink may also be mixed using a disperser such as a bead mill and a high-pressure jet mill.

[0058] [Physical Properties] The electron beam curable inkjet ink of the present invention preferably has a viscosity of 100 mPa s or less, and more preferably 30 mPa s or less, at a temperature of 60° C. or higher. In the present invention, the viscosity can be measured using an E-type viscometer (TV-22: manufactured by Toki Sangyo Co., Ltd.).

[0059] In the electron beam curable inkjet ink of the present invention, the ink solidification start temperature is preferably 20°C or more and less than 100°C. When the ink solidification start temperature is 20°C or more, the ink solidifies quickly after landing on the substrate, thereby suppressing ink bleeding. When the ink solidification start temperature is less than 100°C, the ink melted by heating can be ejected from the inkjet head, so the ink can be ejected more stably. From the viewpoint of energy load, the ink solidifies more quickly and can be ejected at a lower temperature, and the ink solidification start temperature is more preferably 30°C or more and less than 80°C.

[0060] The ink solidification start temperature can be determined by measuring the change in the calorific value of the ink using a differential scanning calorimeter. In the present invention, the ink sample was held at 90° C. for 3 minutes and then cooled at a rate of 10° C. / min. The ink solidification start temperature was determined as the temperature at which the exothermic peak rose.

[0061] [Image forming method] The process for producing a printed matter using the electron beam curable inkjet ink of the present invention will be described. In the method for producing a printed matter of the present invention, an image is formed on the surface of a substrate by the following (Step 1) to (Step 3). (Step 1) heating an electron beam curable inkjet ink to a temperature equal to or higher than the ink's solidification initiation temperature; (Step 2) ejecting ink droplets from the nozzles of an ejection head and causing them to land on the surface of a substrate; (Step 3) A step of curing the ink by irradiating it with an electron beam.

[0062] (Process 1) In this process, the ink tank, the inkjet head, the flow path connecting the ink tank and the inkjet head, etc. are heated to a temperature equal to or higher than the ink solidification temperature. If the ink does not have a viscosity that allows it to be ejected from the inkjet head even at a temperature equal to or higher than the ink solidification temperature, the ink is heated to a temperature at which it can be ejected.

[0063] (Process 2) The electron beam curable inkjet ink of the present invention is preferably ejected by an inkjet method. As a means for discharging ink by the inkjet method, it is preferable to use an inkjet head. As an inkjet head, for example, a charge control type that uses electrostatic attraction to discharge ink, a drop-on-demand type (pressure pulse type) that uses the vibration pressure of a piezoelectric element, an acoustic inkjet type that converts an electric signal into an acoustic beam and irradiates the ink to discharge ink using radiation pressure, a thermal inkjet (Bubble Jet (registered trademark)) type that heats the ink to form bubbles and uses the generated pressure, etc. are preferably used, and the pressure pulse type that uses a piezoelectric element is particularly preferable. In addition, it is also possible to use a multi-pass type, a single-pass type (one-pass printing type), etc.

[0064] Specific examples of the substrate include glass, quartz, aluminum, paper (e.g., ordinary paper having no ink-receiving layer, media used in gravure printing or offset printing, etc., paper exclusively for inkjet printing having an ink-receiving layer, film exclusively for inkjet printing, glossy paper, etc.), plastic film (e.g., polyolefin resin, polyamide resin, polyester resin, polycycloolefin resin, cellulose acetate, acrylic resin, chlorinated polyolefin resin, polyethersulfone resin, polyethylene, polystyrene, polycarbonate resin, polyethylene naphthalate, nylon, polyvinyl acetal, etc.), etc. Among these, polyolefin resin, polyamide resin, and polyester resin are preferable for packaging, and polypropylene, polyethylene, polyethylene terephthalate, and nylon are more preferable.

[0065] The surface of the substrate may be uneven, which may cause deterioration of image quality. Therefore, in order to use the substrate as a printing substrate, it is preferable to perform a surface modification treatment to make the substrate uniform. As the surface modification treatment, a known surface modification treatment selected from corona discharge treatment, plasma treatment, and frame treatment is preferable. Here, it is generally known that the effect of the surface modification treatment decreases over time. For this reason, it is preferable to perform the surface modification treatment step and the inkjet recording step consecutively, and it is preferable to perform the surface modification treatment step immediately before the inkjet recording step. In addition, it is also preferable to modify the outermost surface of the substrate by using a pretreatment agent or the like.

[0066] (Step 3) In the method for producing a printed matter of the present invention, the deposited ink is irradiated with an electron beam to cure it.

[0067] The accelerating voltage of the electron beam is preferably set to a level that allows sufficient energy to reach the inside of the ink to sufficiently cause the reaction of the polymerizable compound, and does not cause significant deterioration of the substrate. For example, from the viewpoint of minimizing migration and suppressing deterioration of the substrate, the accelerating voltage of the electron beam is preferably 10 to 150 kV, more preferably 30 to 120 kV.

[0068] When electron beams are used in the atmosphere, there is a risk of decomposing oxygen and generating a large amount of ozone, so the electron beam irradiation device is used under a low oxygen concentration. In the present invention, the oxygen concentration is preferably 1000 ppm or less. Furthermore, if the oxygen concentration is 50 to 500 ppm, the ink can be sufficiently cured and a sufficient printing speed can be maintained, which is more preferable in terms of quality and productivity.

[0069] The electron beam curable inkjet ink of the present invention has low migration and high abrasion resistance, and is therefore applicable to printing on various packages and the like, as well as various other printing applications.

[0070] In the inkjet image forming method, in order to obtain a high-definition, high-resolution image, it is preferable that each dot is small. In order to obtain small dots, a process called pinning is sometimes provided in an ultraviolet-curing inkjet system. This is a process in which ink is discharged from a nozzle and irradiated with ultraviolet light immediately after it lands on a substrate. This allows dots to be formed quickly after landing, making it possible to obtain an image with a small dot diameter, and achieving high image quality with ultraviolet-curing inkjet ink. On the other hand, with electron beam-curing inkjet ink, pinning curing by ultraviolet light is not possible, and the dot diameter becomes large, making it difficult to obtain high-resolution image quality.

[0071] The ink of the present invention, which was liquid, solidifies immediately after landing, making it possible to suppress the spread of dots on the substrate, i.e., to obtain small dot diameters. This can be easily confirmed by dropping a fixed amount of ink droplets onto a glass substrate and measuring the dot diameter. EXAMPLES

[0072] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the text, "parts" and "%" are by weight unless otherwise specified.

[0073] [Synthesis Example 1] A flask equipped with a thermometer, a condenser, and a stirrer was charged with 408.31 g of methyl ethyl ketone, 267.19 g of stearyl alcohol (NAA-45 manufactured by NOF Corporation, hydroxyl value 210 mgKOH / g), and 141.12 g of 2-isocyanatoethyl acrylate (Kalends AOI-VM manufactured by Showa Denko K.K., molecular weight 141.12), and reacted at 80°C. After 8 hours of reaction, the isocyanate content was determined by adding an excess of amine and back titrating with hydrochloric acid, and it was confirmed that the value was less than 0.1% of the residual amount of isocyanate calculated from the calculated value. Next, the methyl ethyl ketone was distilled off under reduced pressure to obtain a solid reaction product (A-1). The resulting reaction product (A-1) 1 The H-NMR chart is shown in Figure 1. 1 H-NMR(400MHz, CDCl3) δ(ppm)=6.42(d,1H),6.12(q,1H),5.84(d,1H),4.95(br,1H),4.22(t,2H),4.03(t,2H),3.46(q,2H),1.58(br,2H),1.23(br,32H),0.86(t,3H)

[0074] [Preparation Example 1]: Preparation of dispersion 10g of Solsperse 32000 (manufactured by Lubrizol) and 70g of dipropylene glycol diacrylate (DPGDA) were placed in a dispersion vessel and mixed to make a uniform liquid. 20g of CIPigmnet Blue 15:4 (manufactured by Dainichiseika Chemicals Co., Ltd. CHROMOFINEBLUE 4851) was added thereto, and 100g of 0.3mm glass beads were further added, and dispersion treatment was performed for 6 hours with a sand mill. After dispersion treatment, dipropylene glycol diacrylate was added so that the pigment concentration became 12%, and the glass beads used for dispersion were removed by filtering with glass fiber filter paper GA-100 (manufactured by Toyo Roshi Co., Ltd.), and a pigment dispersion liquid with a concentration of 12% was prepared.

[0075] [Preparation Example 2]: Preparation of ink The A-1 obtained in Synthesis Example 1, the pigment dispersion obtained in Preparation Example 1, BYK-UV3510 (manufactured by BYK Chemie, polyether-modified polydimethylsiloxane), dipropylene glycol diacrylate (DPGDA), and stearyl alcohol (NAA-45 manufactured by NOF Corporation, hydroxyl value 210 mgKOH / g) were used and mixed so that the components in the ink were as shown in Table 1, and then impurities were filtered out using a 3 μm membrane filter, thereby obtaining the inkjet inks of Example 1 and Comparative Examples 1 and 2.

[0076] The inkjet inks of Example 1 and Comparative Examples 1 and 2 were subjected to the various tests shown below, and the results are shown in Table 1.

[0077] (viscosity measurement) The viscosity was measured at 50° C. using an E-type viscometer (TV-22, manufactured by Toki Sangyo Co., Ltd.).

[0078] (Measurement of solidification start temperature) Using a differential scanning calorimeter (DSC Q2000: manufactured by TA Instruments), the inkjet ink (2 mg) was held at 90°C for 3 minutes and then cooled to -20°C at 10°C / min to measure the solidification start temperature. The measurement chart for Example 1 is shown in Figure 2, and the measurement chart for Comparative Example 1 is shown in Figure 3. The solidification start temperature of the ink of Example 1 was 36°C. No exothermic peak associated with solidification was observed for the ink of Comparative Example 1.

[0079] (image quality) Using a micropipette, 20 μL droplets of inkjet ink were dropped from a height of 5 mm onto a glass substrate and a polyethylene terephthalate film (E5102: manufactured by Toyobo), and the spread of the droplets after 5 minutes was measured and used as the dot diameter. Each experiment was performed six times, and the average value was calculated. The experiments were performed in a laboratory set at 25° C., and the inks of Example 1 and Comparative Example 2 were preheated to 60° C. before use.

[0080] (Preparation of evaluation specimens) A 10 cm square glass plate was placed on a hot plate at 60° C., and the inkjet ink heated to 60° C. was applied to the glass plate to a thickness of 20 μm over an area of ​​8 cm square using a bar coater heated to 60° C. Next, electron beam curing was performed in an atmosphere with an oxygen concentration of 300 ppm under conditions of an accelerating voltage of 100 kV and a dose of 50 kGy to obtain a test piece.

[0081] (Abrasion resistance) The prepared test pieces were rubbed back and forth 10 times under a load of 300 g using a Gakushin type rub fastness tester RT-200 manufactured by Daiei Scientific Instruments Co., Ltd., and the cured surface was visually observed and evaluated according to the following criteria. A: Almost no scratches were found on the printed image. B: Slight scratches were found on the printed image. C: Very large scratches were found on the printed image.

[0082] (Adhesion) Using the prepared test pieces, a 1 cm wide piece of Scotch tape (registered trademark) was attached to a length of 5 cm on the cured surface, and after peeling off the Scotch tape (registered trademark) surface was visually observed and evaluated according to the following evaluation criteria. A: There is no print on it. B: Print is slightly unattached C: Printed matter is stuck to the surface

[0083] (Solvent resistance) The cured surface of the prepared test piece was rubbed with a cotton swab soaked in 95% ethanol and evaluated according to the following criteria. A: The cotton swab does not stain, and there are no rubbing marks on the surface of the printed material. B: The cotton swab does not stain, but there are faint marks of rubbing on the surface of the print. C: The cotton swab is discolored and has been rubbed onto the surface of the print.

[0084] (Migration) A 3cm x 5cm test piece was cut out from the prepared test piece using a laser cutter, and its weight (W1) was measured. This was left in refluxing methyl ethyl ketone for about 8 hours to extract the eluted components, and then dried at 80°C for 3 hours and at 120°C for 5 hours, and its weight (W2) was measured. Weight reduction rate (%)=(W1-W2)×100 / W1 A: Weight loss rate is less than 2% B: Weight loss rate is 2% or more and less than 5% C: Weight reduction rate is 5% or more

[0085] [Table 1]

[0086] The ink of Example 1 achieved good results in all evaluations. On the other hand, the ink of Comparative Example 1, which does not contain component (A), does not have a solidification initiation temperature, and therefore has problems with image quality. The ink of Comparative Example 2, in which component (A) is changed to stearyl alcohol, has problems with solvent resistance, migration, etc. [Industrial Applicability]

[0087] The electron beam-curable inkjet ink of the present invention has low migration, excellent abrasion resistance, and excellent image quality, and is expected to be a useful electron beam-curable inkjet ink for food and pharmaceutical packaging.

Claims

1. The composition comprises a polymerizable compound (A) having a long-chain alkyl group having from 6 to 30 carbon atoms in the molecule, a hydrogen-bonding group, and a polymerizable group, a polymerizable compound (B) other than the component (A), and a colorant (C), the component (B) is one or more selected from neopentyl glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, polytetramethylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and ethylene oxide-modified trimethylolpropane triacrylate; the weight loss rate calculated by the following formula (1) when the cured product is left in methyl ethyl ketone under reflux for 8 hours is less than 2%, 1. An electron beam curable inkjet ink comprising: Weight reduction rate (%) = (W1-W2) x 100 / W1...Formula (1)

2. 2. The electron beam curable ink-jet ink according to claim 1, wherein the component (A) is a reaction product of an alcohol compound (a) having from 12 to 30 carbon atoms and an isocyanate compound (b) having a (meth)acrylate group.

3. 3. The electron beam curable ink-jet ink according to claim 1, wherein the content of the component (A) in the total amount of the electron beam curable ink-jet ink is 0.5 to 90% by weight.

4. 4. The electron beam curable ink-jet ink according to claim 1, wherein the solidification initiation temperature is 20° C. or higher and lower than 100° C.

5. A printed matter using the electron beam curable inkjet ink according to any one of claims 1 to 4.

6. An image forming method comprising the following steps (Step 1) to (Step 3). (Step 1) A step of heating the electron beam curable inkjet ink according to any one of claims 1 to 4 to a temperature equal to or higher than the ink solidification start temperature. (Step 2) A step of ejecting droplets of the electron beam curable inkjet ink according to any one of claims 1 to 4 from the nozzles of an ejection head and landing them on a substrate surface. (Step 3) A step of further irradiating the ink with an electron beam to cure the ink.

Images