Active energy ray-curable ink composition

Abstract

To provide an actinic-ray-curable ink composition that has good flowability and good dry-down and scratch resistance in printed matter obtained by using it, while reducing the use of photoinitiators by using monomers and oligomers that can polymerize without using the photoinitiators, and also reducing the use of diallyl phthalate resin out of consideration for the environment.SOLUTION: The actinic-ray-curable ink composition comprises: at least one (A) component selected from among (A1) polymers of allyl monomers, (A2) rosin-modified resins, and (A3) terpene monomer skeleton-containing resins; and a (B) component, which is (B1) a monomer and / or oligomer having an amine functional group and / or (B2) a combination of a monomer and / or oligomer not having an amine functional group but having an aryl ketone skeleton or alkyl aryl ketone skeleton with a polyether acrylate having an amine functional group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an actinic ray-curable ink composition. [Background technology]

[0002] When printing using an ink composition, various printing methods are appropriately selected according to the material and shape of the substrate to be printed, and an ink composition having appropriate properties is also selected according to the printing method. For example, for flat printing paper, an offset printing method using a lithographic plate is selected, and an offset printing ink composition containing vegetable oil or mineral oil and having high viscosity is used in this printing method. For printing on corrugated paper, a flexographic printing method using a rubber relief plate is selected, and an aqueous flexographic printing ink composition with extremely high fluidity is used in this printing method. In addition, as is well known, various printing methods such as gravure printing, screen printing, letterpress printing, and inkjet printing are appropriately selected for printing.

[0003] In printing, in addition to depositing an ink composition on a substrate to form an image, drying of the ink composition after printing is also an important factor. Immediately after printing, the ink composition is not sufficiently fixed on the surface of the substrate, resulting in problems such as the ink composition adhering to fingers when touched with a finger or the image being distorted and smeared when rubbed. For this reason, when the printed substrate is sent for post-processing, it is necessary for the ink composition to be sufficiently fixed (i.e., dried) on the surface of the substrate. The process of fixing (i.e., drying) the ink composition after printing varies depending on the type of ink composition used, and includes, for example, penetration of the solvent into the substrate, evaporation of the solvent from the substrate, and polymerization due to oxidation of components contained in the ink composition. In either case, the drying process requires a certain amount of time, and with technological advances resulting in increased printing speeds, the time required for the drying process is no longer negligible.

[0004] In light of this situation, printing using active energy ray-curable ink compositions has recently been practiced. When an active energy ray-curable ink composition is irradiated with ultraviolet light or electron beams, the components contained in the ink composition undergo high molecular weight, resulting in drying. The time required for this drying is extremely short, and printing using this ink composition meets the demand for quickly sending printed materials to post-processing. An example of an ink composition compatible with this drying method is proposed in, for example, Patent Document 1.

[0005] Incidentally, active energy ray-curable ink compositions generally contain a photopolymerization initiator as one of their components to generate radical species for polymerizing monomers or oligomers upon irradiation with active energy rays. This photopolymerization initiator generates low-molecular-weight decomposition products upon irradiation with active energy rays. These decomposition products can cause a characteristic odor in printed matter after drying. Therefore, from the perspective of reducing the odor of printed matter, it is desirable to minimize the generation of such decomposition products. As an example of a technology that meets this need, Patent Document 2 discloses that the use of specific monomers or oligomers can impart drying properties to an ink composition without using a photopolymerization initiator. The ink composition described in Patent Document 2 maintains performance such as pigment dispersibility and drying properties by using a resin such as a diallyl phthalate resin in addition to the specific monomers or oligomers.

[0006] However, diallyl phthalate, a raw material for producing diallyl phthalate resin, is a phthalate ester, which is a chemical substance that is of concern for its effects on the human body and the environment. Although the diallyl phthalate resin obtained by polymerizing this ester is harmless, given the concerns about the raw material, it is preferable to reduce its use.

[0007] Meanwhile, it has been proposed to use a polymer (hereinafter also referred to as an allyl polymer) obtained by polymerizing an ester of a cycloalkanecarboxylic acid or a cycloalkenecarboxylic acid with allyl alcohol as one of the components of a photocurable resin composition that can also be used as an ink composition (see, for example, Patent Document 3). The allyl polymer obtained from an allyl alcohol ester of cyclohexanedicarboxylic acid, which is considered a preferred example in this document, corresponds to a diallyl phthalate resin in which the benzene ring is replaced with cyclohexane, and is expected to be used as a binder resin for active energy ray-curable ink compositions, similar to diallyl phthalate resin. Furthermore, since the raw material is a mono- or polycarboxylic acid ester of a cycloalkane or cycloalkene, rather than a phthalate ester, which is hazardous to the human body and the environment, it is expected that such concerns will be further alleviated. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-193677 [Patent Document 2] Patent No. 7062816 [Patent Document 3] Japanese Patent Application Publication No. 2019-026675 Summary of the Invention [Problem to be solved by the invention]

[0009] However, according to the investigations of the present inventors, it has become clear that when the above-mentioned specific monomers or oligomers are used to obtain an actinic ray-curable ink composition that does not contain a photopolymerization initiator, when the allyl polymer described in Patent Document 3 is used as a binder resin, not only does the fluidity of the ink composition decrease, reducing printability, but also printed matter obtained by printing using this composition suffers from problems such as increased dry-down and reduced scratch resistance. In other words, when a substitute for the diallyl phthalate resin is used in an actinic ray-curable ink composition that does not contain a photopolymerization initiator, sufficient performance cannot be obtained.

[0010] The present invention has been made in view of the above circumstances, and has an object to provide an active energy ray-curable ink composition that has good fluidity and can improve the dry-down and scratch resistance of printed matter obtained using the ink composition, while reducing the use of photopolymerization initiators by using monomers or oligomers that can be polymerized without the use of photopolymerization initiators, and further reducing the use of diallyl phthalate resins in consideration of the environment. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve the above problems and have found that the above problems can be solved by using a specific resin (component (A) described below) in combination with a specific monomer and / or oligomer (component (B) described below), thereby completing the present invention. Specifically, the present invention provides the following.

[0012] (1) The present invention provides an actinic ray-curable ink composition comprising: component (A), which is at least one selected from the following (A1), (A2), and (A3), and which further contains a pigment dispersant when (A1) is selected alone from these selections; component (B), which is composed of the following (B1) and / or (B2); a compound having an ethylenically unsaturated bond that does not fall under either component (A) or component (B); and a pigment, wherein the content of component (B) is 15% by mass or more of the total. (A1) A polymer of an allyl monomer represented by the following general formula (1): (A2) Rosin-modified resin (A3) Terpene Monomer Skeleton-Containing Resin (B1) Monomers and / or oligomers with amine functional groups (B2) Both a monomer and / or oligomer having an aryl ketone skeleton or an alkylaryl ketone skeleton but no amine functional group, and a polyether acrylate having an amine functional group [ka] (In the above general formula (1), R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X is an n-valent group consisting of a 4- to 8-membered alicyclic skeleton, and n is 2 or 3.

[0013] (2) The present invention also provides the actinic ray-curable ink composition according to item (1), wherein X in the general formula (1) is a divalent group represented by any one of the following formulas: [ka]

[0014] (3) The present invention also provides an actinic ray-curable ink composition according to item (1) or (2), wherein the weight-average molecular weight of (A2) and (A3) is 1,000 or more and 100,000 or less.

[0015] (4) The present invention also provides an actinic ray-curable ink composition according to any one of (1) to (3), wherein the total content of the component (A) is 5% by mass to 20% by mass of the total.

[0016] (5) The present invention also provides an actinic ray-curable ink composition according to any one of (1) to (4), wherein the rosin-modified resin is a rosin-modified polyester resin.

[0017] (6) The present invention also provides an actinic ray-curable ink composition according to any one of items (1) to (5), wherein X in the general formula (1) is a 1,2-cyclohexylene group. [Effects of the Invention]

[0018] According to the present invention, there is provided an active energy ray-curable ink composition that has good fluidity and can improve the dry-down and scratch resistance of printed matter obtained using the ink composition, while reducing the use of photopolymerization initiators by using monomers and oligomers that can be polymerized without the use of photopolymerization initiators and further reducing the use of diallyl phthalate resins in consideration of the environment. DETAILED DESCRIPTION OF THE INVENTION

[0019]

[0033] Hereinafter, one embodiment of the active energy ray-curable ink composition of the present invention (hereinafter, appropriately abbreviated as "ink composition") will be described. Note that the present invention is not limited to the following embodiment, and can be practiced by making appropriate modifications within the scope of the present invention.

[0020] The actinic radiation-curable ink composition of the present invention has the ability to cure upon irradiation with actinic radiation such as ultraviolet rays or electron beams. As described below, the ink composition of the present invention contains a compound (e.g., a monomer or oligomer) having an ethylenically unsaturated bond. When irradiated with actinic radiation, radicals generated in the ink composition polymerize the compound having the ethylenically unsaturated bond, thereby curing the ink composition. Therefore, when actinic radiation is irradiated to an ink composition that is sticky on the surface of a printed material immediately after printing, the ink composition instantly cures to form a film and becomes dry (tack-free). When ultraviolet radiation is used as the actinic radiation, the component (B) described below functions as a photopolymerization initiator, generating radicals or exhibiting a sensitizing effect upon irradiation with ultraviolet radiation, thereby curing the ink composition. When electron beams are used as the actinic radiation, various components contained in the ink composition undergo intramolecular cleavage upon irradiation with electron beams, generating radicals and thereby curing the ink composition. Therefore, the ink composition of the present invention does not necessarily need to contain a photopolymerization initiator as a constituent component, but may use one appropriately if necessary.

[0021] Examples of active energy rays used to cure the ink composition of the present invention include ultraviolet rays and electron beams. Among these, ultraviolet rays are preferred from the standpoints of device cost and ease of use. However, in recent years, the introduction of electron beam generators into printing devices has progressed, and from this standpoint, electron beams are also preferred. When ultraviolet rays are used as active energy rays, their wavelength may be appropriately determined according to the absorption wavelength of the photopolymerization initiator used, but examples include 400 nm or less. Examples of ultraviolet irradiation devices that generate such ultraviolet rays include metal halide lamps, high-pressure mercury lamps, excimer lamps containing rare gases, and ultraviolet light-emitting diodes (LEDs). When electron beams are used as active energy rays, the irradiation device for irradiating the electron beam is not particularly limited. Examples of such irradiation devices include Cockcroft-Wartsin type, Van de Graaff type, and resonant transformer type irradiation devices. The energy of the electron beam is preferably 50 to 1000 eV, more preferably 100 to 300 eV. Whichever active energy ray is used, the amount of irradiation is adjusted appropriately while observing the degree of curing of the ink composition.

[0022] The printing method to which the ink composition of the present invention is applied is not particularly limited. Examples of such printing methods include offset printing, waterless offset printing, letterpress printing, rubber relief printing, flexographic printing, gravure printing, and inkjet printing. Properties such as viscosity of the ink composition may be appropriately set depending on the printing method to which the ink composition is applied. Among these, offset printing and waterless offset printing are preferred as printing methods to which the present invention is applied.

[0023] The ink composition of the present invention is characterized by comprising: component (A), which is at least one selected from (A1), (A2), and (A3) described below; component (B), which is composed of (B1) and / or (B2), also described below; a compound having an ethylenically unsaturated bond that does not fall into either component (A) or component (B); and a pigment, wherein the content of component (B) is 15% by mass or more of the total. The ink composition of the present invention does not necessarily need to contain a photopolymerization initiator, but may contain one. Each component will be described below.

[0024] [Component (A)] Component (A) is at least one selected from (A1), (A2), and (A3) described below. When (A1) is selected alone from these options, the ink composition of the present invention further contains a pigment dispersant. By including component (A) in the ink composition of the present invention, the ink composition can be made less in use of photopolymerization initiators, and further, in consideration of the environment, the ink composition can be made less in use of diallyl phthalate resins, while still providing good fluidity and achieving dry-down and scratch resistance in printed materials obtained using the ink composition. These components (A) are described below.

[0025] (A1) is a polymer of an allyl monomer represented by the following general formula (1).

[0026] [ka]

[0027] In the above general formula (1), R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. In this specification, "independently" means that each is determined independently and without regard to the other, and may be the same or different. Examples of such alkyl groups include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a pentyl group. In a preferred embodiment, R 1 and R 2and R are each a hydrogen atom, but are not particularly limited thereto.

[0028] In the above general formula (1), n ​​is 2 or 3, and X is an n-valent group consisting of a 4- to 8-membered alicyclic skeleton. The "n-valent group consisting of a 4- to 8-membered alicyclic skeleton" means an n-valent group formed by bonds to other groups from n carbon atoms among the carbon atoms constituting an alicyclic ring having 4 to 8 carbon atoms. Preferred examples of the alicyclic ring include cycloalkanes and cycloalkenes having 4 to 8 carbon atoms. Note that X may be intramolecularly crosslinked, and examples of intramolecularly crosslinked X include adamantane, norbornene, and norbornane.

[0029] In a more specific embodiment, X is preferably a divalent group represented by any of the following general formulae: In this case, n in the above general formula (1) is 2.

[0030] [ka]

[0031] Among the Xs represented by the general formula above, a 1,2-cyclohexylene group is particularly preferred. In this case, the 1- and 2-positions of cyclohexane are substituted with the groups represented by the parenthesized portions of general formula (1) above.

[0032] Preferred examples of the allyl monomer represented by the general formula (1) include diallyl 1,2-cyclohexanedicarboxylate, diallyl 1,3-cyclohexanedicarboxylate, diallyl 1,4-cyclohexanedicarboxylate, diallyl 4-cyclohexene-1,2-dicarboxylate, diallyl 2-cyclohexene-1,2-dicarboxylate, etc. Among these, diallyl 1,2-cyclohexanedicarboxylate, diallyl 4-cyclohexene-1,2-dicarboxylate, and diallyl 1,4-cyclohexanedicarboxylate are more preferred, and diallyl 1,2-cyclohexanedicarboxylate is even more preferred.

[0033] The allylic monomer represented by the general formula (1) is a cycloalkane or cycloalkene having 4 to 8 carbon atoms and having two or three carboxy groups, and a substituent R 1 and R 2 It can be obtained by esterifying an allyl alcohol having the substituent R 1 and R 2 As already mentioned, it is preferable that both of are hydrogen atoms.

[0034] To obtain a polymer by polymerizing the allyl monomer represented by the general formula (1), the allyl monomer may be polymerized using a radical polymerization initiator. Examples of such radical polymerization initiators include azo initiators such as azobisisobutyronitrile and 2,2'-azobisisobutyrate dimethyl, peroxide initiators such as ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, peroxyesters, and benzoyl peroxide, acetophenone initiators such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 1-hydroxycyclohexylphenyl ketone, benzoin initiators such as benzoin and benzoin ethyl ether, benzophenone initiators such as benzophenone, phosphorus initiators such as acylphosphine oxides, sulfur initiators such as thioxanthone, and benzyl initiators such as benzyl and 9,10-phenanthrenequinone. These polymerization initiators can be used alone or in combination of two or more.

[0035] The amount of the polymerization initiator is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 0.001 to 3 parts by mass, relative to 100 parts by mass of the allylic monomer represented by general formula (1). The reaction temperature during polymerization is preferably about 60 to 240°C. The reaction time is preferably about 0.1 to 100 hours.

[0036] When the allylic monomer represented by the general formula (1) is polymerized to obtain a polymer, it may be a homopolymer using a single allylic monomer, or a copolymer combining multiple types of allylic monomers or other monomers. The most preferred embodiment is a homopolymer of 1,2-cyclohexanedicarboxylate diallyl, but is not particularly limited thereto.

[0037] The weight average molecular weight of the polymer is preferably 300,000 or less, more preferably 200,000 or less, even more preferably about 2,000 to 150,000, and particularly preferably 5,000 to 140,000.

[0038] Such polymers may be synthesized as described above, or may be commercially available products, such as those manufactured by Osaka Soda Co., Ltd.

[0039] When (A1) is selected alone as the component (A), the component (A) further contains a pigment dispersant. That is, as described above, the component (A) is at least one selected from (A1) and the components (A2) and (A3) described below. When (A1) is selected alone from these, a pigment dispersant is further included as the component (A). When (A1) is used in combination with (A2) and / or (A3), the component (A) does not necessarily need to contain a pigment dispersant. Even in this case, the component (A) may contain a pigment dispersant. When (A1) is used alone as the component (A), the ink composition tends to have insufficient fluidity, and therefore a pigment dispersant is used in combination with it to compensate for this fluidity.

[0040] Pigment dispersants are components used to improve pigment dispersibility in ink compositions. Examples of such components include, without limitation, those that have been used in ink compositions to date. Examples of pigment dispersants include sorbitan fatty acid esters, partial fatty acid esters of polyacrylic acid, alkylamine fatty acid salts, and alkyldiamines. However, any pigment dispersant that has the ability to disperse pigments is acceptable, and is not limited to these. Such pigment dispersants are commercially available, including the Solsperse series manufactured by Lubrizol, the DISPERBYK series manufactured by BYK Japan, the Ajinomoto Fine-Techno Co., Ltd. AJISPER series manufactured by Ajinomoto Fine-Techno Co., Ltd., and the EFKA series manufactured by BASF.

[0041] The content of the pigment dispersant in the ink composition is preferably 0.5 to 5 mass%, more preferably 0.5 to 3 mass%, and even more preferably 0.5 to 1.5 mass%. The amount of pigment dispersant added to the pigment contained in the ink composition is preferably 1 to 20 mass%, more preferably 2 to 10 mass%, based on the pigment.

[0042] (A2) is a rosin-modified resin. Rosin-modified resins are resins prepared by modifying rosins. Examples of such rosins include gum rosin, wood rosin, and tall oil rosin, which are primarily composed of resin acids such as abietic acid, palustric acid, neoabietic acid, pimaric acid, isopimaric acid, and dehydroabietic acid. Examples of such rosins include disproportionated rosins obtained by disproportionating these rosins, polymerized rosins obtained by dimerization or further polymerization, hydrogenated rosins obtained by hydrogenation, and modified rosins obtained by partially maleating and / or fumarating rosin. Maleic anhydride is used to maleate rosin, and fumaric acid is used to fumarate rosin. The addition reaction of maleic anhydride and / or fumaric acid to rosin can be carried out by known methods. For example, the raw rosin can be heated and melted, and maleic anhydride and / or fumaric acid can be added to the melt. The reaction may be carried out either under elevated pressure or under normal pressure.

[0043] The rosin-modified resin may be any resin having a monomer structure based on rosin, and examples thereof include rosin-modified alkyd resins, rosin-modified polyester resins, rosin-modified maleic acid resins (maleic rosin polyesters), rosin-modified fumaric acid resins (fumarized rosin polyesters), rosin-modified phthalic acid resins (phthalated rosin polyesters), rosin-modified phenolic resins, and rosin-modified petroleum resins. These rosin-modified resins are commercially available and readily available. Examples of such commercially available products include Hartall R-WW, Haritac AQ-90A, and Harimac T-80 manufactured by Harima Chemical Industries, Ltd., and Chugoku Rosin WW and Marquid 382 manufactured by Arakawa Chemical Industries, Ltd. The rosin-modified resin may be commercially available, or may be synthesized by known means.

[0044] The weight-average molecular weight of the rosin-modified resin is preferably 1,000 or more and 100,000 or less. A weight-average molecular weight of 1,000 or more is preferred because it provides excellent pigment dispersibility and imparts good viscoelasticity to the ink composition, while a weight-average molecular weight of 100,000 or less is preferred because it provides good solubility and excellent handleability. A more preferred weight-average molecular weight of the rosin-modified resin is approximately 5,000 or more and 70,000 or less.

[0045] Among these, preferred rosin-modified polyester resins include condensation polymers of polyhydric alcohols and acid components including resin acids, fatty acids, and polybasic acids. The acid value of the rosin-modified polyester resin is preferably about 1 to 50 mgKOH / g. By keeping the acid value at 50 mgKOH or less, problems such as abnormal emulsification can be suppressed in offset printing ink compositions using the rosin-modified polyester resin. The acid value is preferably 1 to 25 mgKOH, and more preferably 1 to 10 mgKOH.

[0046] As described above, the rosin-modified polyester resin is preferably a condensation polymer of an acid component including a resin acid, a fatty acid, and a polybasic acid, and a polyhydric alcohol. Next, these components will be described.

[0047] Resin acids refer to abietic acid and its isomers contained in rosins, as well as their derivatives. Rosins are non-volatile components of pine resin collected from plants of the Pinaceae family, and are primarily composed of abietic acid and its isomers. Examples of abietic acid and its isomers include abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, and dehydroabietic acid, all of which have a carboxy group and can form esters with polyhydric alcohols described below. Introducing such resin acids into a rosin-modified polyester resin can improve affinity for pigments and increase the proportion of biomass-derived components in the resulting rosin-modified polyester resin.

[0048] Although the above-mentioned abietic acid and its isomers contain only one carboxyl group, multiple carboxyl groups can be introduced by modifying them. For example, abietic acid is a trans-diene compound, but it can be isomerized to a cis-diene compound by heating. Multiple carboxyl groups can be introduced into the abietic acid skeleton by subjecting the resulting cis-diene compound to a Diels-Alder reaction with a dienophile compound containing multiple carboxyl groups, such as maleic acid or 1,2-cyclohexene dicarboxylic acid. Furthermore, polymerized rosin can be synthesized by polymerizing multiple molecules of abietic acid or its isomers, and these compounds also contain multiple carboxyl groups. The derivatives of abietic acid and its isomers refer to these compounds.

[0049] Since rosins are primarily composed of resin acid, rosins themselves may be used in place of the resin acid. Several types of rosins are known, differing in their production methods and subsequent chemical treatments, and any of these may be used. Examples of such rosins include gum rosin, wood rosin, tall rosin, disproportionated rosin, hydrogenated rosin, and polymerized rosin. Rosins may also be modified by the Diels-Alder reaction described above. From the standpoint of storage stability, it is preferable to use rosins that chemically have no or few conjugated double bonds. Examples of such rosins include disproportionated rosin and hydrogenated rosin. Although rosins with conjugated double bonds are somewhat inferior in terms of storage stability of the synthesized resin, they can also be used without any problems.

[0050] Fatty acids are obtained by hydrolyzing natural fats and oils such as vegetable oils and animal oils, and because they have one carboxyl group, they can form esters with polyhydric alcohols, which will be described later. By incorporating such fatty acids into rosin-modified polyester resins, the proportion of biomass-derived components in the resulting rosin-modified polyester resin can be increased. From this perspective, it is preferable to use fatty acids in an amount such that the oil length, which is the ratio (mass %) of the mass of the fatty acid moiety to the mass of the entire resin, is approximately 30 to 85, and more preferably approximately 50 to 85.

[0051] Examples of fatty acids include caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, arachidic acid, and behenic acid. Fatty acids have a carboxyl group and can be considered to be compounds with a relatively high sp value. Among these fatty acids, the lower the carbon number, the higher the sp value tends to be. From this perspective, in the present invention, fatty acids with 8 to 16 carbon atoms are preferably used, and fatty acids with 8 to 14 carbon atoms are more preferably used. Furthermore, while the fatty acid may be either unsaturated or saturated, those with one or fewer unsaturated bonds in the molecule are preferred to avoid coloration due to deterioration. For fatty acids with two or more unsaturated bonds, such as oleic acid, linoleic acid, and eleostearic acid, it is preferable to use those in which the double bonds have been epoxidized and eliminated by oxidation. Such modified fatty acids can also be used as fatty acids in the present invention. These fatty acids can be used alone or in combination of two or more.

[0052] The polybasic acid is a compound having multiple carboxyl groups, and is a component for polycondensation with a polyhydric alcohol (described later) to increase the molecular weight. As the compound having multiple carboxyl groups, any compound that has been used in the synthesis of alkyd resins can be used without limitation, and it may have two or more carboxyl groups, or may be an acid anhydride thereof.

[0053] Examples of such compounds include phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, trimellitic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexenedicarboxylic acid, 1,4-cyclohexenedicarboxylic acid, hexahydrophthalic anhydride, 5-sodiosulfoisophthalic acid, fumaric acid, benzoic acid, tert-butylbenzoic acid, tetrahydrophthalic anhydride, maleic anhydride, succinic acid, succinic anhydride, fumaric acid, sebacic acid, azelaic acid, tetrabromophthalic anhydride, methylhimic anhydride, tetrachlorophthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride, trimellitic anhydride, methylcyclohexenedicarboxylic anhydride, etc. These may be used alone or in combination of two or more.

[0054] The polyhydric alcohol forms an ester with the acid components, including the resin acid, fatty acid, and polybasic acid, as already explained, to increase the molecular weight of these components. As the polyhydric alcohol, any of those that have been used in the synthesis of alkyd resins can be used without limitation, and examples thereof include compounds having two or more hydroxyl groups.

[0055] Such compounds include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, 1,3-butanediol, neopentyl glycol, spiroglycol, dioxane glycol, adamantanediol, 3-methyl-1,5-pentanediol, methyloctanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 2-methylpropanediol 1,3, 3-methylpentanediol 1,5, hexamethylene glycol, and the like. Examples of the polyol include ethylene oxide-modified compounds of bifunctional phenols such as bisphenol A, propylene oxide-modified compounds of bifunctional phenols such as bisphenol A, ethylene oxide- and propylene oxide-copolymerized compounds of bisphenol A, copolymerized polyether polyols of ethylene oxide and propylene oxide, polycarbonate diols, adamantane diols, polyether diols, polyester diols, and polycaprolactone diols. These may be used alone or in combination of two or more.

[0056] In order to adjust the molecular weight of the rosin-modified polyester resin, a monobasic acid other than a fatty acid may be added as an acid component, such as benzoic acid, acetic acid, propionic acid, or butyric acid.

[0057] Next, a method for preparing a rosin-modified polyester resin using these materials will be described. Rosin-modified polyester resins are prepared by reacting an acid component containing a resin acid, a fatty acid, and a polybasic acid with a polyhydric alcohol. One example of the reaction procedure involves adding a small amount of a solvent such as xylene to a reactor containing these raw materials while injecting an inert gas such as nitrogen gas into the reactor, heating the reactor, and then azeotropically removing the condensed water while carrying out condensation polymerization. The reaction temperature can be approximately 170 to 250°C, and the reaction time can be approximately 5 to 25 hours, but is not particularly limited. The completion of the reaction can be determined by monitoring the acid value of the reaction mixture over time. That is, the reaction can be completed when the decrease in the acid value of the reaction mixture accompanying the condensation polymerization stops. The condensation polymerization reaction can be carried out in a shorter time by distilling the water generated by the condensation polymerization out of the system or by using a reaction catalyst. Examples of reaction catalysts include tetrabutyl zirconate, monobutyltin oxide (monobutyltin oxide), zirconium naphthate, and tetrabutyl titanate.

[0058] (A3) is a terpene monomer skeleton-containing resin. The terpene monomer skeleton-containing resin is a resin having a terpene-derived structure in its structure, and examples of such resins include terpene resins prepared by polymerizing only terpene monomers, and various resins prepared by polymerizing a terpene monomer in combination with other monomer components.

[0059] Terpene monomers, also known as terpene compounds, have unsaturated bonds in their molecules and can be polymerized alone or with other monomers to form polymers. Examples of such terpene monomers include α-pinene, β-pinene, carene, α-terpinene, ν-terpinene, d-limonene, dipentene, terpinolene, α-phellandrene, β-phellandrene, paramenthadienes, pyronene, camphene, alloocimene, and myrcene. Preferred examples include d-limonene, dipentene, α-phellandrene, β-phellandrene, and α-terpinene. The terpene monomers may be used alone or in combination of two or more.

[0060] Other monomer components that can be used in combination with the terpene monomer include unsaturated dicarboxylic acids, unsaturated dicarboxylic anhydrides, unsaturated dicarboxylic acid dialkyl esters, phenols, acrylates, vinyl compounds such as styrene, etc. These monomer components are polymerized with the terpene monomer through a cycloaddition reaction such as the Diels-Alder reaction, a radical polymerization reaction, a cationic polymerization reaction, etc. Examples of the unsaturated dicarboxylic acid include maleic acid and fumaric acid.

[0061] Examples of the terpene monomer skeleton-containing resin include terpene resin, aromatic modified terpene resin, terpene phenol resin, hydrogenated terpene phenol resin, etc. Various types of these are commercially available, for example, products manufactured by Yasuhara Chemical Co., Ltd. and Arakawa Chemical Industries, Ltd.

[0062] The weight-average molecular weight of the terpene monomer skeleton-containing resin is preferably 1,000 or more and 100,000 or less. A weight-average molecular weight of 1,000 or more of the terpene monomer skeleton-containing resin is preferred because it provides excellent pigment dispersibility and imparts good viscoelasticity to the ink composition, while a weight-average molecular weight of 100,000 or less is preferred because it provides good solubility and excellent handleability. A more preferred weight-average molecular weight of the terpene monomer skeleton-containing resin is about 5,000 or more and 70,000 or less.

[0063] The content of component (A) in the ink composition is preferably from 5 to 40% by mass, more preferably from 5 to 30% by mass, even more preferably from 5 to 20% by mass, and particularly preferably from 5 to 15% by mass.

[0064] [(B) Component] Component (B) consists of (B1) and / or (B2) described below. Component (B) is a compound or group of compounds that exhibit sensitization and radical generation capabilities upon exposure to active energy rays, and that themselves contain ethylenically unsaturated bonds and are polymerizable. When a typical photopolymerization initiator is used, the molecule cleaves to generate radicals, resulting in cleavage fragments (low-molecular-weight compounds). These fragments remain in the cured film of the ink composition and are gradually released from the film to the outside, causing odor generation and migration. In contrast, with component (B) used in the present invention, the cleavage fragments remaining after radical generation contain ethylenically unsaturated bonds, and thus are polymerized together with components such as monomers and oligomers to form a high molecular weight polymer. In this case, the cleavage fragments remain in the polymer and are not released from the cured film to the outside, thereby suppressing odor generation and migration. These components (B) are described below.

[0065] (B1) is a monomer and / or oligomer having an amine functional group. The amine functional group here refers to a primary, secondary, or tertiary amino group, preferably a tertiary amino group. That is, the monomer or oligomer having an amine functional group is a monomer or oligomer to which a primary, secondary, or tertiary amino group has been added. Examples of the monomer or oligomer having an amine functional group include amine-modified monomers or oligomers, such as amino acrylate monomers, amino methacrylate monomers, amine-modified polyester acrylates, amine-modified polyester methacrylates, amine-modified polyether acrylates, amine-modified polyether methacrylates, and polyurethane acrylates. The amine-modified oligomer can be obtained, for example, by a Michael addition reaction between a primary amine and an acrylate. The monomer and / or oligomer having an amine functional group generates radicals when irradiated with active energy rays.

[0066] Examples of amine-modified oligomers include EBECRYL LEO10101, EBECRYL80, EBECRYL81, EBECRYL83, and EBECRYL7100 manufactured by Daicel-Allnex Co., Ltd., ETERCURE63922 manufactured by Eternal Corporation, CN549NS, CN550, and CN551NS manufactured by SARTOMER, PHOTOCRYL A104 and Miramer AS1000 manufactured by MIWON, and AgiSyn701, AgiSyn701P, AgiSyn703, and AgiSyn703TF manufactured by DSM.

[0067] (B2) is both a monomer and / or oligomer having an aryl ketone skeleton or an alkylaryl ketone skeleton but no amine functional group, and a polyether acrylate having an amine functional group, i.e., (B2) includes both of these.

[0068] Monomers and / or oligomers having an aryl ketone skeleton or an alkylaryl ketone skeleton but no amine functional group have both the properties of a photopolymerization initiator and the properties of a monomer or oligomer, and therefore have self-curing properties upon irradiation with active energy rays. Here, having self-curing properties means having the property of being able to cure without a photopolymerization initiator.

[0069] The monomer and / or oligomer having an aryl ketone skeleton or an alkylaryl ketone skeleton without having an amine functional group is not particularly limited as long as it has an aryl ketone skeleton or an alkylaryl ketone skeleton, and examples thereof include polyether acrylate, polyether methacrylate, polyester acrylate, polyester methacrylate, and polyurethane acrylate having these skeletons in the molecule.

[0070] The aryl ketone skeleton includes a skeleton represented by the following general formula (2). The aryl ketone skeleton in which R is an aryl group includes a benzophenone skeleton, a benzophenone derivative skeleton, a thioxanthone skeleton, a thioxanthone derivative skeleton, an anthraquinone skeleton, or an anthraquinone derivative skeleton. The alkyl aryl ketone skeleton is a skeleton represented by the following general formula (2) in which R is an alkyl group.

[0071] [ka]

[0072] The benzophenone skeleton may have a substituent. Such a substituent is one in which a hydrogen atom bonded to a carbon atom of the benzene ring of the benzophenone skeleton is substituted with another substituent. Examples of the substituent include, but are not limited to, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms and containing a hetero atom, and a hetero atom (e.g., ═O). Examples of the benzophenone derivative skeleton include one in which one or two carbon atoms of the benzene ring are substituted with a hetero molecule. Examples of the hetero molecule include an oxygen atom, a sulfur atom, or a nitrogen atom.

[0073] The thioxanthone skeleton may have a substituent. Such a substituent is formed by substituting a hydrogen atom bonded to a carbon atom of the benzene ring of the thioxanthone skeleton with another substituent. Examples of the substituent include, but are not limited to, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms and containing a heteroatom, and a heteroatom (e.g., ═O). Examples of the thioxanthone derivative skeleton include those in which one or two carbon atoms of the benzene ring are substituted with a heteroatom. Examples of the heteroatom include an oxygen atom, a sulfur atom, and a nitrogen atom.

[0074] The anthraquinone skeleton may have a substituent. Such a substituent is one in which a hydrogen atom bonded to a carbon atom of the benzene ring of the anthraquinone skeleton is substituted with another substituent. Examples of the substituent include, but are not limited to, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms and containing a heteroatom, and a heteroatom (for example, ═O). Examples of an anthraquinone derivative skeleton include one in which one or two carbon atoms of the benzene ring are substituted with a heteroatom. Examples of the heteroatom include an oxygen atom, a sulfur atom, and a nitrogen atom.

[0075] Examples of the alkyl group in the alkyl aryl ketone skeleton include an alkyl group having 1 to 6 carbon atoms and a cycloalkyl group having 3 to 8 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Examples of the cycloalkyl group having 3 to 8 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. The alkyl aryl ketone skeleton may have a substituent. In such a substituent, a hydrogen atom bonded to a carbon atom of the benzene ring group of the alkyl aryl ketone skeleton is replaced with another substituent. Examples of the substituent include, but are not limited to, an alkyl group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms and containing a heteroatom, and a heteroatom (e.g., ═O).

[0076] Examples of the monomer and / or oligomer having an aryl ketone skeleton or an alkylaryl ketone skeleton without an amine functional group include EBECRYL LEO10103 manufactured by Daicel-Allnex Corporation.

[0077] The polyether acrylate having an amine functional group is the above-mentioned polyether acrylate having an amine functional group, for example, EBECRYL LEO10551 manufactured by Daicel-Allnex Corporation.

[0078] The content of component (B) in the ink composition is 15% by mass or more, preferably 15 to 40% by mass, more preferably 15 to 30% by mass, and even more preferably 15 to 20% by mass.

[0079] [Compounds with ethylenically unsaturated bonds] The ink composition of the present invention contains an ethylenically unsaturated bond that does not fall under either of the above components (A) and (B). Among the compounds selected as the above components (A) and (B), there are compounds having an ethylenically unsaturated bond, but the compound having an ethylenically unsaturated bond used here is different from those selected as the components (A) and (B).

[0080] Compounds having ethylenically unsaturated bonds are components that polymerize to a high molecular weight by radicals generated in the ink composition, and are called monomers, oligomers, etc. Various ethylenically unsaturated bond-containing polymers with even higher molecular weights than oligomers are also commercially available. These polymers can also be crosslinked by the above-mentioned monomers or oligomers, or by crosslinking with each other to achieve a high molecular weight. Therefore, these polymers may be used together with the above-mentioned monomers or oligomers as compounds having ethylenically unsaturated bonds. As mentioned above, these radicals are generated from the above-mentioned component (B) upon irradiation with active energy rays.

[0081] Monomers are components that have ethylenically unsaturated bonds and polymerize to a high molecular weight as described above. However, before polymerization, they are often liquid components with relatively low molecular weights. They are used as solvents when dissolving resin components to produce varnishes, and for adjusting the viscosity of ink compositions. Examples of monomers include monofunctional monomers with one ethylenically unsaturated bond in the molecule and difunctional or higher monomers with two or more ethylenically unsaturated bonds in the molecule. Difunctional or higher monomers can crosslink molecules when the ink composition cures, thereby contributing to accelerating the curing rate and forming a strong film. While monofunctional monomers do not have the crosslinking ability described above, they contribute to reducing cure shrinkage associated with crosslinking. Various combinations of these monomers can be used as needed.

[0082] Examples of monofunctional monomers include alkyl acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, and dodecyl (meth)acrylate, (meth)acrylic acid, (meth)acrylates of ethylene oxide adducts, (meth)acrylates of propylene oxide adducts, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, tricyclodecane monomethylol (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 2-hydroxy-3-butoxypropyl (meth)acrylate. Examples of the monofunctional monomer include α-(meth)acrylate, 2-hydroxy-3-methoxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, glycerin mono(meth)acrylate, acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, β-carboxyethyl (meth)acrylate, (meth)acrylic acid dimer, ω-carboxypolycaprolactone mono(meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-vinylpyrrolidone, N-vinylformamide, and (meth)acryloylmorpholine. These monofunctional monomers can be used alone or in combination of two or more. In this specification, "(meth)acrylate" means "acrylate and / or methacrylate", and "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid".

[0083] Examples of difunctional or higher functional monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, pentyl glycol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. Glycol di(meth)acrylate, hydroxypivalyl hydroxypivalate di(meth)acrylate, hydroxypivalyl hydroxypivalate dicaprolactonate di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,2-hexanediol di(meth)acrylate, 1,5-hexanediol di(meth)acrylate, 2,5-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,2-octanediol Di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,2-decanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,2-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,2-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,2-hexadecanediol di(meth)acrylate, 2-methyl- 2,4-pentanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-methyl-2-propyl-1,3-propanediol di(meth)acrylate, 2,4-dimethyl-2,4-pentanediol di(meth)acrylate, 2,2-diethyl-1,3-propanediol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, dimethylol octane di(meth)acrylate, 2-ethyl-1,3-hexanediol di(meth)acrylate,2,5-dimethyl-2,5-hexanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 2,4-diethyl-1,5-pentanediol di(meth)acrylate, 1,2-hexanediol di(meth)acrylate, 1,5-hexanediol di(meth)acrylate, 2,5-hexanediol di(meth)acrylate, 2-methyl-2,4-pentanedi(meth)acrylate, 2,4-diethyl-1,5-pentanedi All di(meth)acrylate, tricyclodecane dimethylol di(meth)acrylate, tricyclodecane dimethylol dicaprolactonate di(meth)acrylate, bisphenol A tetraethylene oxide adduct di(meth)acrylate, bisphenol F tetraethylene oxide adduct di(meth)acrylate, bisphenol S tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol A tetraethylene oxide adduct di(meth)acrylate, hydrogenated bisphenol F tetraethylene oxide adduct di(meth)acrylate Bifunctional monomers such as acrylate, hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol F di(meth)acrylate, bisphenol A tetraethylene oxide adduct dicaprolactonate di(meth)acrylate, and bisphenol F tetraethylene oxide adduct dicaprolactonate di(meth)acrylate; glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tricaprolactonate tri(meth)acrylate, and trimethylolethane tri(meth)acrylate; Trifunctional monomers such as trimethylolhexane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate; trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tetracaprolactonate tetra(meth)acrylate, diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and ditrimethylolpropane tetracaprolactonate tetra(meth)acrylate;Examples of such monomers include tetrafunctional or higher monomers such as ditrimethylolethane tetra(meth)acrylate, ditrimethylolbutane tetra(meth)acrylate, ditrimethylolhexane tetra(meth)acrylate, ditrimethyloloctane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, and tripentaerythritol polyalkylene oxide hepta(meth)acrylate. Among these, preferred examples include trimethylolpropane triacrylate (TMPTA; trifunctional), ditrimethylolpropane tetraacrylate (Di-TMPTA; tetrafunctional), dipentaerythritol hexaacrylate (DPHA; hexafunctional), glycerin propoxy triacrylate (GPTA; trifunctional), and hexanediol diacrylate (HDDA; bifunctional). These difunctional or higher functional monomers can be used alone or in combination of two or more.

[0084] Another type of monomer is epoxidized vegetable oil acrylate, which is obtained by acrylic modification of epoxidized vegetable oil. This is a compound in which (meth)acrylic acid is ring-opened and added to the epoxy group of epoxidized vegetable oil, which has been epoxidized at the double bond of unsaturated vegetable oil with an oxidizing agent such as peracetic acid or perbenzoic acid. Unsaturated vegetable oils are triglycerides in which at least one fatty acid has at least one carbon-carbon unsaturated bond. Examples include hemp seed oil, linseed oil, perilla oil, oiticica oil, olive oil, cocoa oil, kapok oil, kaya oil, mustard oil, apricot kernel oil, tung oil, kukui oil, walnut oil, poppy seed oil, sesame oil, safflower oil, radish seed oil, soybean oil, tung oil, camellia oil, corn oil, rapeseed oil, niger oil, rice bran oil, palm oil, castor oil, sunflower oil, grape seed oil, almond oil, pine seed oil, cottonseed oil, coconut oil, peanut oil, and dehydrated castor oil. Because these monomers are derived from vegetable oils, they are useful for increasing the amount of biomass components in the ink composition. Various epoxidized vegetable oil acrylates are commercially available, so they may also be used.

[0085] As described above, oligomers are components that polymerize to a high molecular weight, but because they are originally relatively high molecular weight components, they are also used to impart appropriate viscosity and elasticity to ink compositions. Examples of oligomers include epoxy-modified (meth)acrylates, exemplified by esters of (meth)acrylic acid with hydroxyl groups generated after ring-opening of epoxy groups contained in epoxy compounds such as epoxy resins with an acid or base; rosin-modified epoxy acrylates; polyester-modified (meth)acrylates, exemplified by esters of (meth)acrylic acid with terminal hydroxyl groups of condensation polymers of dibasic acids and diols; polyether-modified (meth)acrylates, exemplified by esters of (meth)acrylic acid with terminal hydroxyl groups of polyether compounds; and urethane-modified (meth)acrylates, exemplified by esters of (meth)acrylic acid with terminal hydroxyl groups of condensation polymers of polyisocyanate compounds and polyol compounds. Such oligomers are commercially available and can be obtained under product names such as the EBECRYL series manufactured by Daicel-Allnex Co., Ltd., the CN and SR series manufactured by SARTOMER, the ARONIX M-6000 series, 7000 series, 8000 series, ARONIX M-1100, ARONIX M-1200, and ARONIX M-1600 manufactured by Toagosei Co., Ltd., and NK Oligo manufactured by Shin-Nakamura Chemical Co., Ltd. These oligomers can be used alone or in combination of two or more types.

[0086] The polymer having an ethylenically unsaturated bond is a component that increases in molecular weight together with the above-mentioned monomers and oligomers, and since it has a large molecular weight even before being irradiated with active energy rays, it is a component that is useful for improving the viscoelasticity of the ink composition. Such a polymer is used, for example, in a state dissolved or dispersed in a monomer, which is a low-viscosity liquid. Examples of the polymer having an ethylenically unsaturated bond include an acrylic resin having an unreacted unsaturated group and an acrylic-modified phenolic resin.

[0087] The content of the compound having an ethylenically unsaturated bond that does not fall under either component (A) or component (B) in the ink composition is preferably 5 to 40% by mass, more preferably 5 to 20% by mass. By ensuring that the content of the compound having an ethylenically unsaturated bond that does not fall under either component (A) or component (B) is within the above range, it is possible to achieve both good curability and good printability. Furthermore, the content of the polymer having an ethylenically unsaturated bond is preferably 0 to 50% by mass, more preferably 0 to 30% by mass, and even more preferably 0 to 20% by mass. Having the polymer content within the above range is preferable because it can impart appropriate viscoelasticity to the ink composition to suppress the occurrence of misting and the like, while also ensuring good curability of the ink composition.

[0088] [Pigment] The pigment is a component added to the ink composition of the present invention to impart coloring power, hiding power, etc., and examples thereof include color pigments, white pigments, metal powders, etc. Examples of such pigments include, without particular limitation, organic and / or inorganic pigments that have conventionally been used in ink compositions.

[0089] Examples of pigments include yellow pigments such as disazo yellow (pigment yellow 12, pigment yellow 13, pigment yellow 14, pigment yellow 17, pigment yellow 1) and Hansa yellow; magenta pigments such as brilliant carmine 6B, lake red C, and watching red; cyan pigments such as phthalocyanine blue, phthalocyanine green, and alkali blue; black pigments such as carbon black; white pigments such as titanium oxide; and metal powders such as aluminum paste and bronze powder.

[0090] The content of the pigment is, for example, about 1 to 30 mass % of the total ink composition, but is not particularly limited. When preparing a colored ink composition, it is also possible to use a coloring component of another color as a complementary color, or to add an ink composition of another color.

[0091] [Other ingredients] In addition to the above components, other components may be added to the ink composition of the present invention as needed, such as extender pigments, polymerization inhibitors, salts such as phosphates, waxes such as polyethylene wax, olefin wax, and Fischer-Tropsch wax, and alcohols.

[0092] The extender pigment is a component that imparts suitable printability, viscoelasticity, and other properties to the ink composition, and various types of extender pigments commonly used in preparing ink compositions can be used. Examples of such extender pigments include clay, kaolinite (kaolin), barium sulfate, magnesium sulfate, calcium carbonate, silicon oxide (silica), bentonite, talc, mica, and titanium oxide. The amount of such extender pigment added is, for example, about 0 to 33% by mass of the total ink composition, but is not particularly limited.

[0093] Preferred examples of the polymerization inhibitor include phenolic compounds such as butylhydroxytoluene, tocopherol acetate, nitrosamines, benzotriazole, and hindered amines, with butylhydroxytoluene being a more preferred example. Adding such a polymerization inhibitor to the ink composition can prevent the ink composition from thickening due to a polymerization reaction during storage. The content of the polymerization inhibitor in the ink composition is, for example, about 0.01 to 1% by mass.

[0094] Conventionally known methods can be used to prepare the ink composition of the present invention using the above components. Examples of such methods include mixing the above components, grinding them in a bead mill or triple-roll mill, etc. to disperse the pigment (i.e., the coloring component and the extender pigment), adding additives (polymerization inhibitors, alcohols, waxes, etc.) as needed, and further adjusting the viscosity by adding the above-mentioned monomer components and oil components. For example, in the case of an ink composition for offset printing, the viscosity of the ink composition is, for example, 10 to 70 Pa·s as measured at 25°C using a Raley viscometer, but this is not particularly limited. [Example]

[0095] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the following examples in any way.

[0096] [Preparation of Rosin-Modified Polyester Resin A] A reactor equipped with a stirrer, reflux condenser, and thermometer was charged with 125 parts by weight of epoxidized soybean oil, 375 parts by weight of disproportionated rosin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name: "dehydroabietic acid," acid value 136 mg KOH / g), 1.5 parts by weight of triphenylphosphine, 25 parts by weight of 1,2-cyclohexene dicarboxylic acid, and 25 parts by weight of glycerin, and the mixture was reacted under a nitrogen atmosphere at 200°C for 5 hours to carry out a condensation polymerization (dehydration condensation) reaction, thereby preparing rosin-modified polyester resin A. The resulting rosin-modified polyester resin A had a weight-average molecular weight of 35,000 and an acid value of 3.5 mg KOH / g.

[0097] [Preparation of Rosin-Modified Polyester Resin B] A reaction kettle equipped with a stirrer, reflux condenser, and thermometer was charged with 125 parts by weight of coconut oil fatty acid, 375 parts by weight of disproportionated rosin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name: "dehydroabietic acid," acid value 136 mg KOH / g), 1.5 parts by weight of triphenylphosphine, 25 parts by weight of 1,2-cyclohexene dicarboxylic acid, and 25 parts by weight of glycerin, and the mixture was reacted under a nitrogen atmosphere at 200°C for 5 hours to carry out a condensation polymerization (dehydration condensation) reaction, thereby preparing rosin-modified polyester resin B. The resulting rosin-modified polyester resin B had a weight-average molecular weight of 25,000 and an acid value of 3.0 mg KOH / g.

[0098] [Preparation of Varnish 1] A four-neck flask equipped with a condenser, thermometer, and stirrer was charged with 30 parts by weight of a 1,2-cyclohexanedicarboxylate diallyl polymer (Osaka Soda Co., Ltd., product name: RADPAR-AD032), 69.4 parts by weight of trimethylolpropane triacrylate (TMPTA), and 0.2 parts by weight of dibutylhydroxytoluene (BHT). The contents were then heated to 140°C and maintained at that temperature for 50 minutes to dissolve the resin. Next, 0.4 parts by weight of aluminum ethyl acetoacetate diisopropylate (ALCH, Kawaken Fine Chemicals Co., Ltd.) was charged into the reaction vessel, and the contents were heated to 170°C and maintained at that temperature for 60 minutes to gel the contents, yielding Varnish 1. Varnish 1 is a varnish containing the polymer of an allylic monomer represented by the general formula (1) above, i.e., (A1) above.

[0099] [Preparation of Varnish 2] Varnish 2 was obtained in the same manner as varnish 1, except that a diallyl isophthalate polymer (manufactured by Osaka Soda Co., Ltd., product name: Daiso Isodap) was used instead of the diallyl 1,2-cyclohexanedicarboxylate polymer. Varnish 2 is a varnish containing a diallyl phthalate resin.

[0100] [Preparation of Varnish 3] Varnish 3 was obtained in the same manner as varnish 1, except that a diallyl phthalate polymer (manufactured by Osaka Soda Co., Ltd., product name: Daisodapp A) was used instead of the diallyl 1,2-cyclohexanedicarboxylate polymer. Varnish 3 is a varnish containing a diallyl phthalate resin.

[0101] [Preparation of Varnish A] Varnish A was obtained in the same manner as varnish 1, except that rosin-modified polyester resin A was used instead of the polymer of 1,2-cyclohexanedicarboxylate diallyl. Varnish A is a varnish containing a rosin-modified resin, i.e., the above (A2).

[0102] [Preparation of Varnish B] Varnish B was obtained in the same manner as varnish 1, except that rosin-modified polyester resin B was used instead of the polymer of 1,2-cyclohexanedicarboxylate diallyl. Varnish B is a varnish containing a rosin-modified resin, i.e., the above (A2).

[0103] [Preparation of Varnish C] Varnish C was obtained in the same manner as Varnish 1, except that a terpene resin (Yasuhara Chemical Co., Ltd., product name: YS Resin PX1000) was used instead of the 1,2-cyclohexanedicarboxylate diallyl polymer. Varnish C is a varnish containing a terpene monomer skeleton-containing resin, i.e., the above (A3).

[0104] The components were mixed according to the formulations shown in Tables 1 to 3, milled using a three-roll mill at a roll temperature of 40°C until the particle size was 5.0 μm or less, and 5 parts by mass of trimethylolpropane triacrylate (TMPTA) was added as needed to adjust the viscosity to around 40 Pa s, thereby preparing the ink compositions of Examples 1 to 19 and Comparative Examples 1 to 7. The blend amounts in Tables 1 to 3 are in parts by mass.

[0105] The explanation of each material listed in Tables 1 to 3 is as follows. Black pigment: Carbon black (Mitsubishi Chemical Corporation, product name: MA-70) Yellow pigment: Pigment Yellow 13 (Clariant Chemicals, product name: BHS) Crimson pigment: Pigment Red 57:1 (Clariant Chemicals, product name: L5B) Indigo pigment: Copper phthalocyanine pigment (manufactured by DIC Corporation, product name: FASTOGEN Blue FDB13) (B1): Oligomer having an amine functional group (manufactured by Daicel-Allnex Corporation, product name: EBECRYL LEO10101; corresponding to (B1) above) (B2a): A self-curing photopolymerizable oligomer having an aryl ketone skeleton or an alkylaryl ketone skeleton but no amine functional group (manufactured by Daicel-Allnex Corporation, product name: EBECRYL LEO10103; when combined with the following (B2b), it corresponds to the above (B2)) (B2b): Polyether acrylate having an amine functional group (manufactured by Daicel-Allnex Corporation, product name: EBECRYL LEO10551; a combination of this with (B2a) corresponds to (B2) above) TMPTA: Trimethylolpropane triacrylate Pigment dispersant: Comb-type basic dispersant (manufactured by Lubrizol, product name: Solsperse 39000) Wax: Polyethylene wax (Morimura Chemical Co., Ltd., product name: NJ-100)

[0106] [Liquidity assessment] For each of the ink compositions of the Examples and Comparative Examples, the flow value was measured using a spread meter, and the fluidity was examined as the flow slope value. The flow slope value is the value obtained by subtracting the value obtained by measuring the spread diameter after 10 seconds in mm from the value obtained by measuring the spread diameter after 100 seconds in mm using a spread meter; the larger this value, the better the fluidity. The evaluation criteria were as follows, and the results are shown in the "Fluidity" column in Tables 1 to 3. ○: Flow gradient value is 4.0 or more △: Flow gradient value is 2.0 or more and less than 4.0 ×: Flow gradient value is less than 2.0

[0107] [Drydown rating: 1] Dry-down evaluation was carried out when drying using an ozone-free ultraviolet lamp. First, for each of the ink compositions of the Examples and Comparative Examples, 0.1 cc of the ink composition sample was taken and spread on aurora coated paper using an RI spreader (two-split roll, manufactured by Akira Seisakusho Co., Ltd.), and immediately irradiated with ultraviolet light (ozone-free UV lamp manufactured by Eye Graphics Co., Ltd., 120 W / cm 2A print was produced by passing the print directly under the lamp at a speed and frequency of 130 m / min (1 pass). The density of the print was measured immediately after production, and then left indoors for 24 hours before measuring the density again. The dry-down value was calculated by subtracting the density value after 24 hours from the density value immediately after application. The evaluation criteria were as follows, and the results are shown in the "Dry-down 1" column in Tables 1 to 3. A Spectroeye densitometer manufactured by Gretagmacbeth was used to measure the density of the print. ○: Dry down value is -0.2 or more (decrease in concentration is 0.2 or less) ×: Dry down value is less than -0.2 (decrease in concentration is greater than 0.2)

[0108] [Drydown rating: 2] Dry-down evaluation was carried out when drying using a high-pressure mercury lamp. First, for each of the ink compositions of the Examples and Comparative Examples, 0.1 cc of the ink composition sample was taken and spread on aurora coated paper using an RI spreader (two-split roll, manufactured by Akira Seisakusho Co., Ltd.), and immediately irradiated with ultraviolet light (high-pressure mercury lamp manufactured by Eye Graphics Co., Ltd., 120 W / cm 2 A print was produced by passing the print directly under the lamp at a speed and frequency of 130 m / min, 3 passes. The density of the print was measured immediately after production, and then left indoors for 24 hours before measuring the density again. The dry-down value was calculated by subtracting the density value after 24 hours from the density value immediately after application. The evaluation criteria were as follows, and the results are shown in the "Dry-down 2" column in Tables 1 to 3. A Spectroeye densitometer manufactured by Gretagmacbeth was used to measure the density of the print. ○: Dry down value is -0.2 or more (decrease in concentration is 0.2 or less) ×: Dry down value is less than -0.2 (decrease in concentration is greater than 0.2)

[0109] [Scratch resistance rating 1] Scratch resistance was evaluated when the ink composition was dried using an ozone-free ultraviolet lamp. First, for each of the ink compositions of the Examples and Comparative Examples, 0.1 cc of the ink composition sample was taken and spread on aurora coated paper using an RI spreader (two-split roll, manufactured by Akira Seisakusho Co., Ltd.), and immediately irradiated with ultraviolet light (ozone-free UV lamp manufactured by Eye Graphics Co., Ltd., 120 W / cm 2 A print was produced by passing the print directly under the lamp at a speed and frequency of 130 m / min, 1 pass. The coating film of the print was then rubbed with a fingernail to determine the number of rubs required until the coating film peeled off. The evaluation criteria were as follows, and the results are shown in the "Scratch Resistance 1" column of Tables 1 to 3. ○: The coating does not peel off even after rubbing 10 times △: The coating peeled off after 6 to 9 rubs ×: The coating peeled off after rubbing 1 to 5 times

[0110] [Scratch resistance rating 2] Scratch resistance was evaluated when the ink compositions were dried using a high-pressure mercury lamp. First, 0.1 cc of each ink composition sample was taken and spread on aurora coated paper using an RI spreader (two-split roll, manufactured by Akira Seisakusho Co., Ltd.), and immediately irradiated with ultraviolet light (high-pressure mercury lamp manufactured by Eye Graphics Co., Ltd., 120 W / cm 2 A print was produced by passing the print directly under the lamp at a speed and frequency of 130 m / min, 3 passes. The coating film of this print was then rubbed with a fingernail to determine the number of rubs required until the coating film peeled off. The evaluation criteria were as follows, and the results are shown in the "Scratch Resistance 2" column of Tables 1 to 3. ○: The coating does not peel off even after rubbing 10 times △: The coating peeled off after 6 to 9 rubs ×: The coating peeled off after rubbing 1 to 5 times

[0111] [Table 1]

[0112] [Table 2]

[0113] [Table 3]

[0114] Comparing the examples and comparative examples shown in Tables 1 to 3, it can be seen that the ink composition of the present invention has good properties even without using a diallyl phthalate resin or a photopolymerization initiator.

Claims

1. Component (A), which is at least one selected from the following (A1), (A2), and (A3), and when (A1) is selected alone from these selections, the component (A) further contains a pigment dispersant; Component (B) consisting of the following (B1) and / or (B2); 1. An active energy ray-curable ink composition comprising: a compound having an ethylenically unsaturated bond that does not fall under either component (A) or component (B); and a pigment, wherein the content of component (B) is 15 mass% or more of the total. (A1) A polymer of an allyl monomer represented by the following general formula (1): (A2) Rosin-modified resin (A3) Terpene Monomer Skeleton-Containing Resin (B1) Monomers and / or oligomers with amine functional groups (B2) Both a monomer and / or oligomer having an aryl ketone skeleton or an alkylaryl ketone skeleton but no amine functional group, and a polyether acrylate having an amine functional group 【Chemistry 1】 (In the above general formula (1), R １ and R ２ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X is an n-valent group consisting of a 4- to 8-membered alicyclic skeleton, and n is 2 or 3.

2. 2. The actinic ray-curable ink composition according to claim 1, wherein X in the general formula (1) is a divalent group represented by any one of the following formulas: 【Chemistry 2】

3. 3. The actinic ray-curable ink composition according to claim 1, wherein the weight average molecular weight of (A2) and (A3) is 1,000 or more and 100,000 or less.

4. 3. The actinic ray-curable ink composition according to claim 1, wherein the content of the component (A) is 5% by mass to 40% by mass of the total amount.

5. 3. The actinic ray-curable ink composition according to claim 1, wherein the rosin-modified resin is a rosin-modified polyester resin.

6. 3. The active energy ray-curable ink composition according to claim 1, wherein X in the general formula (1) is a 1,2-cyclohexylene group.

Images