UV-curable printing ink composition, method for producing same, and cured film

Abstract

The present invention addresses the problem of providing a UV-curable printing ink composition having excellent adhesion to a substrate. Provided is a UV-curable printing ink composition containing a specific amount of polymer microparticles (A) having a specific composition.

Description

Technical Field

[0001] The present invention relates to a UV curable printing ink composition, a method for producing the same, and a cured film. Background Art

[0002] Conventionally, there are known UV curable resin compositions obtained by mixing an ultraviolet curable resin with a pigment or the like (for example, Patent Documents 1 to 3).

[0003] Patent Document 1 discloses a photocurable liquid solder resist ink composition, wherein polymer microparticles having a Tg of 20° C. or less are dispersed in the solder resist ink composition containing a photocurable resin as an essential component.

[0004] Patent Document 2 discloses a polymerizable compound characterized by being represented by a characteristic general formula.

[0005] Furthermore, Patent Document 3 discloses a liquid crystal sealing resin composition characterized by containing a rubber-modified unsaturated compound, a coupling agent, a filler, and a photopolymerization initiator as essential components.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 9-137109

[0009] Patent Document 2: Japanese Patent Application Publication No. 2008-274216

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 9-236809 Summary of the invention

[0011] However, from the viewpoint of adhesion to the substrate, the above-mentioned conventional techniques are not sufficient and there is room for further improvement.

[0012] One embodiment of the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a UV curable printing ink composition having excellent adhesion to a substrate.

[0013] The present inventors have conducted intensive studies to solve the above-mentioned problems and have completed the present invention.

[0014] A UV curable printing ink composition according to one embodiment of the present invention comprises the following composition:

[0015] A UV curable printing ink composition comprises polymer particles (A) and a pigment (D), wherein the polymer particles (A) comprise a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer, the elastomer comprising one or more selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber, the graft portion comprising a polymer comprising a structural unit derived from one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylate monomers, and the content of the pigment (D) in the UV curable printing ink composition is 1% by weight or more relative to 100% by weight of the UV curable printing ink composition.

[0016] According to one embodiment of the present invention, there is an effect of being able to provide a UV curable printing ink composition having excellent adhesion to a substrate. DETAILED DESCRIPTION

[0017] An embodiment of the present invention is described below, but the present invention is not limited to this. The present invention is not limited to the various structures described below, and various changes can be made within the scope shown in the claims. In addition, embodiments or embodiments obtained by appropriately combining the technical means respectively disclosed in different embodiments or embodiments are also included in the technical scope of the present invention. Moreover, new technical features can be formed by combining the technical means respectively disclosed in each embodiment. It should be noted that all academic literature and patent documents recorded in this specification are cited as references in this specification. In addition, in this specification, unless otherwise specified, "A~B" indicating a numerical range means "above A (including A and larger than A) and below B (including B and smaller than B)".

[0018] [1. Technical concept of the present invention]

[0019] Although water-based printing ink compositions can be used to print on paper, they cannot be used to print on materials that are impermeable to water-based printing ink compositions, such as plastic materials such as films and molded products, and metal materials and glass materials. Therefore, when printing on non-permeable substrates such as plastic materials, metal materials and glass materials, solvent-containing inks and UV-curable printing inks are often used.

[0020] In addition, aqueous printing ink compositions and printing ink compositions containing solvents have the disadvantage that a large amount of energy is required for evaporation and drying. On the other hand, UV curable printing ink compositions are cured immediately by irradiating UV after the printing ink composition is applied to the substrate, so they have the advantage of excellent productivity. In addition, compared with printing ink compositions containing solvents, UV curable printing ink compositions do not need to volatilize the solvent after application, and the waste liquid generated during the manufacturing process does not contain solvents, which is also excellent from the perspective of improving the working environment and reducing the environmental load.

[0021] On the other hand, UV curable printing ink compositions still have problems from the viewpoint of adhesion to substrates.

[0022] The above-mentioned problems are described in detail below.

[0023] First, the UV curable printing ink composition is cured by free radical polymerization. In free radical polymerization, the olefinic double bonds contained in the monomers as the reaction diluent react with each other, thereby generating -C-C- bonds, and the monomers are connected to each other. However, through this polymerization reaction, a significant volume shrinkage of about 10% occurs before and after the curing of the UV curable printing ink composition. Therefore, due to the stress remaining in the cured film (coating film) obtained after the curing of the UV curable printing ink composition, the cured film can be peeled off from the substrate. That is, the previous UV curable printing ink composition has the disadvantage of not having sufficient adhesion to the substrate.

[0024] One embodiment of the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a novel UV curable printing ink composition having excellent adhesion to a substrate.

[0025] The present inventors have conducted intensive studies to solve the above-mentioned problems and have newly found that a UV-curable printing ink composition having excellent adhesion to a substrate can be obtained by forming a UV-curable printing ink composition comprising polymer microparticles (A), wherein the polymer microparticles (A) comprise a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer, wherein the elastomer comprises one or more selected from a diene rubber, a (meth)acrylate rubber and an organosiloxane rubber, and the graft portion comprises a polymer having a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer and a (meth)acrylate monomer, and the UV-curable printing ink composition further comprises a pigment (D), and the content of the pigment (D) in the UV-curable printing ink composition is 1% by weight or more relative to 100% by weight of the UV-curable printing ink composition, and have completed the present invention.

[0026] Furthermore, the present inventors have newly found that by providing a UV curable printing ink composition with the above-mentioned structure, it is possible to achieve both the adhesion of the UV curable printing ink composition to a substrate and the color development of the cured film, which has been difficult to achieve so far.

[0027] [2. UV curable printing ink composition]

[0028] A UV-curable printing ink composition according to one embodiment of the present invention is a UV-curable printing ink composition comprising polymer microparticles (A) and a pigment (D), wherein the polymer microparticles (A) comprise a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer, the elastomer comprising one or more selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber, the graft portion comprising a polymer comprising a structural unit derived from one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylate monomers, and the content of the pigment (D) in the UV-curable printing ink composition is 1% by weight or more relative to 100% by weight of the UV-curable printing ink composition.

[0029] In this specification, a "UV curable printing ink composition" may be referred to as a "printing ink composition", and a "UV curable printing ink composition according to one embodiment of the present invention" may be referred to as a "present printing ink composition". It should be noted that a UV curable printing ink composition may also be referred to as an ink composition for UV curable printing or an ink composition for UV curable printing.

[0030] In addition, in one embodiment of the present invention, a substance obtained by curing the printing ink composition is referred to as a cured film. A cured film formed by curing the present printing ink composition is also one embodiment of the present invention. In this specification, sometimes "a cured film according to one embodiment of the present invention" is referred to as "the present cured film". It should be noted that the cured film is sometimes referred to as a cured film, an ink film or an ink film, which have the same meaning.

[0031] Since the present printing ink composition has the above-mentioned structure, it has the advantage of excellent adhesion to the substrate. It should be noted that in this specification, "excellent adhesion to the substrate" means that when the substrate (for example, PMMA (polymethyl methacrylate) sheet) is subjected to the adhesion test described in the following examples, the result is 1 (acceptable) or more, that is, 2 (good) or 1 (acceptable). That is, the present printing ink composition has the advantage that when the adhesion test described in the following examples is subjected to the PMMA sheet as the substrate, the result is 1 (acceptable) or more, that is, 2 (good) or 1 (acceptable).

[0032] The present printing ink composition may contain a solvent, but the content of the solvent (e.g., an organic solvent) is preferably small. For example, the content of the solvent (e.g., an organic solvent) contained in the printing ink composition is preferably 10% by weight or less, more preferably 5% by weight or less, further preferably 3% by weight or less, further preferably 1% by weight or less, and particularly preferably 0.1% by weight, relative to 100% by weight of the printing ink composition. When the content of the solvent (e.g., an organic solvent) in the present printing ink composition is within the above range, the following advantages are achieved: (a) the amount of solvent discharged is reduced or eliminated, thereby reducing the environmental load, and (b) the time of the drying process for removing the solvent is shortened or unnecessary, thereby achieving an improvement in productivity.

[0033] (2-1. Polymer microparticles (A))

[0034] The polymer microparticles (A) include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer. Since the printing ink composition includes the polymer microparticles (A), it has the advantage of being able to provide a cured film having excellent adhesion. The reason for this is not yet clear, but it is believed that the polymer microparticles (A) can reduce the residual stress in the cured film caused by the volume shrinkage of the cured film during the curing of the printing ink composition, but one embodiment of the present invention is not limited to such speculation.

[0035] (2-1-1. Elastic body)

[0036] The elastomer comprises one or more selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber. In addition to the above-mentioned rubber, the elastomer may also comprise natural rubber. The elastomer may also be referred to as an elastic part or rubber particles. In this specification, (meth)acrylate refers to acrylate and / or methacrylate.

[0037] Hereinafter, the case where the elastomer includes a diene rubber (case A) will be described. In case A, the printing ink composition including the polymer microparticles (A) can provide a cured film having excellent toughness and impact resistance. A cured film having excellent toughness and / or impact resistance is also referred to as a cured film having excellent durability.

[0038] The diene rubber is an elastomer containing a structural unit derived from a diene monomer as a structural unit. The diene monomer may also be referred to as a conjugated diene monomer. In case A, the diene rubber may contain 50 to 100% by weight of a structural unit derived from a diene monomer and 0 to 50% by weight of a structural unit derived from a vinyl monomer other than the diene monomer copolymerizable with the diene monomer in 100% by weight of the structural unit. In case A, the diene rubber may contain a structural unit derived from a (meth) acrylate monomer as a structural unit in an amount less than the structural unit derived from the diene monomer.

[0039] Examples of the diene monomer include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), and 2-chloro-1,3-butadiene. These diene monomers may be used alone or in combination of two or more.

[0040] As vinyl monomers other than diene monomers copolymerizable with diene monomers (hereinafter also referred to as vinyl monomers A), for example, (a) vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; (b) vinyl carboxylic acids such as acrylic acid and methacrylic acid; (c) vinyl cyanides such as acrylonitrile and methacrylonitrile; (d) vinyl halides such as vinyl chloride, vinyl bromide, and chloroprene; (e) vinyl acetate; (f) olefins such as ethylene, propylene, butylene, and isobutylene; (g) polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. The above-mentioned vinyl monomers A may be used alone or in combination of two or more. Among the above-mentioned vinyl monomers A, styrene is particularly preferred.

[0041] In case A, the diene rubber is preferably a butadiene rubber (also called polybutadiene rubber) composed of structural units derived from 1,3-butadiene or a butadiene-styrene rubber (also called polystyrene-butadiene) which is a copolymer of 1,3-butadiene and styrene. As the diene rubber, butadiene rubber is more preferred. That is, the elastomer is preferably butadiene rubber. According to the above-mentioned constitution, the desired effect brought about by the elastomer of the polymer particles (A) containing the diene rubber can be further exerted. In addition, butadiene-styrene rubber is also more preferred in that the transparency of the obtained cured film can be improved by adjusting the refractive index.

[0042] The case where the elastomer includes a (meth)acrylate rubber (case B) will be described. In case B, a wide range of polymer designs of the elastomer can be achieved by combining a plurality of monomers.

[0043] The (meth)acrylate rubber is an elastomer containing a structural unit derived from a (meth)acrylate monomer as a structural unit. In case B, the (meth)acrylate rubber may contain 50 to 100% by weight of a structural unit derived from a (meth)acrylate monomer and 0 to 50% by weight of a structural unit derived from a vinyl monomer other than the (meth)acrylate monomer copolymerizable with the (meth)acrylate monomer, in 100% by weight of the structural unit. In case B, the (meth)acrylate rubber may contain a structural unit derived from a diene monomer as a structural unit in an amount smaller than that derived from the (meth)acrylate monomer.

[0044] Examples of the (meth)acrylate monomers include (a) alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (b) aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; (c) 2-hydroxyethyl (meth)acrylate, (meth)acrylate monomers include hydroxyalkyl (meth)acrylates such as 4-hydroxybutyl (meth)acrylate; (d) glycidyl (meth)acrylate, glycidyl (meth)acrylate alkyl (meth)acrylate; (e) alkoxyalkyl (meth)acrylate; (f) allyl (meth)acrylate, propyl (meth)acrylate and other allyl (meth)acrylate alkyl esters; (g) polyfunctional (meth)acrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and tetraethylene glycol di(meth)acrylate. These (meth)acrylate monomers may be used alone or in combination of two or more. Among these (meth)acrylate monomers, ethyl (meth)acrylate, butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred, and butyl (meth)acrylate is more preferred.

[0045] In case B, the (meth)acrylate rubber is preferably one or more selected from ethyl (meth)acrylate rubber, butyl (meth)acrylate rubber and 2-ethylhexyl (meth)acrylate rubber, and more preferably butyl (meth)acrylate rubber. Ethyl (meth)acrylate rubber is a rubber composed of structural units derived from ethyl (meth)acrylate, butyl (meth)acrylate rubber is a rubber composed of structural units derived from butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate rubber is a rubber composed of structural units derived from 2-ethylhexyl (meth)acrylate. According to this structure, the glass transition temperature (Tg) of the elastomer becomes lower, so that polymer particles (A) with low Tg can be obtained. As a result, (a) the printing ink composition containing the obtained polymer particles (A) can provide a cured film with excellent toughness, and (b) the viscosity of the printing ink composition can be further reduced.

[0046] As the vinyl monomer other than the (meth)acrylate monomer copolymerizable with the (meth)acrylate monomer (hereinafter also referred to as the vinyl monomer B), the monomers listed as the above-mentioned vinyl monomer A can be cited. The vinyl monomer B can be used alone or in combination of two or more. Among the vinyl monomers B, styrene is particularly preferred.

[0047] The case where the elastomer includes an organosiloxane-based rubber (case C) will be described. In case C, the printing ink composition can provide a cured film having sufficient heat resistance and excellent impact resistance at low temperatures.

[0048] Examples of the organosiloxane rubber include (a) organosiloxane polymers composed of alkyl or aryl disubstituted siloxy units such as dimethylsiloxy, diethylsiloxy, methylphenylsiloxy, diphenylsiloxy, and dimethylsiloxy-diphenylsiloxy, and (b) organosiloxane polymers composed of alkyl or aryl monosubstituted siloxy units such as organohydrogensiloxy in which a part of the alkyl group in the side chain is substituted with a hydrogen atom. These organosiloxane polymers may be used alone or in combination of two or more.

[0049] In this specification, a polymer composed of dimethylsiloxy units is referred to as dimethylsiloxy rubber, a polymer composed of methylphenylsiloxy units is referred to as methylphenylsiloxy rubber, and a polymer composed of dimethylsiloxy units and diphenylsiloxy units is referred to as dimethylsiloxy-diphenylsiloxy rubber. In case C, as the organosiloxane rubber, (a) from the viewpoint that the printing ink composition can provide a cured film having excellent heat resistance, one or more selected from dimethylsiloxy rubber, methylphenylsiloxy rubber and dimethylsiloxy-diphenylsiloxy rubber are preferred, and (b) from the viewpoint of easy availability and economical efficiency, dimethylsiloxy rubber is more preferred.

[0050] In case C, the polymer fine particles (A) preferably contain 80% by weight or more, more preferably 90% by weight or more, of the organosiloxane rubber based on 100% by weight of the elastomer contained in the polymer fine particles (A). With the above configuration, the printing ink composition can provide a cured film having excellent heat resistance.

[0051] In one embodiment of the present invention, the elastomer is preferably one or more selected from butadiene rubber, butadiene-styrene rubber, butadiene-(meth)acrylate rubber, ethyl (meth)acrylate rubber, butyl (meth)acrylate rubber, 2-ethylhexyl (meth)acrylate rubber, dimethylsiloxy rubber, methylphenylsiloxy rubber and dimethylsiloxy-diphenylsiloxy rubber, and more preferably one or more selected from butadiene rubber, butadiene-styrene rubber, butyl (meth)acrylate rubber and dimethylsiloxy rubber.

[0052] (Cross-linked structure of elastomer)

[0053] From the perspective of being able to maintain the dispersion stability of the polymer particles (A) in the printing ink composition, it is preferred to introduce a cross-linked structure into the elastomer. As a method for introducing a cross-linked structure into an elastomer, a generally used technique can be adopted, for example, the following method can be cited. That is, in the manufacture of an elastomer, a method can be cited in which a cross-linked monomer such as a multifunctional monomer and / or a mercapto-containing compound is mixed with a monomer that can constitute the elastomer, and then polymerized. In this specification, the step of manufacturing a polymer such as an elastomer is also referred to as a polymer.

[0054] In addition, as a method for introducing a cross-linked structure into an organosiloxane rubber, the following methods can also be cited: (a) a method of using a multifunctional alkoxysilane compound and other materials when polymerizing the organosiloxane rubber; (b) a method of introducing a reactive group (for example, (a) a mercapto group and (b) a reactive vinyl group) into the organosiloxane rubber, and then adding (a) an organic peroxide or (b) a polymerizable vinyl monomer to the obtained reaction product to carry out a free radical reaction; or (c) a method of mixing a multifunctional monomer and / or a cross-linking monomer such as a mercapto-containing compound with other materials when polymerizing the organosiloxane rubber, and then polymerizing the mixture; etc.

[0055] A multifunctional monomer may also be referred to as a monomer having two or more free radical polymerizable reaction groups in the same molecule. The free radical polymerizable reaction group is preferably a carbon-carbon double bond. As a multifunctional monomer, excluding butadiene, examples include (meth)acrylates having ethylenically unsaturated double bonds such as (meth)acrylate allyl alkyl esters and (meth)acrylate allyloxyalkyl esters. As monomers having two (meth)acrylate groups, examples include: ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and polyethylene glycol di(meth)acrylates. As the polyethylene glycol di(meth)acrylates, examples include triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol (600) di(meth)acrylate, and the like. In addition, as a monomer having three (meth) acrylic groups, alkoxylated trimethylolpropane tri(meth)acrylates, glycerol propoxy tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, etc. can be exemplified. As alkoxylated trimethylolpropane tri(meth)acrylates, trimethylolpropane tri(meth)acrylate, trimethylolpropane triethoxy tri(meth)acrylate, etc. can be cited. And, as a monomer having four (meth) acrylic groups, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, etc. can be exemplified. And, as a monomer having five (meth) acrylic groups, dipentaerythritol penta(meth)acrylate, etc. can be exemplified. And, as a monomer having six (meth) acrylic groups, ditrimethylolpropane hexa(meth)acrylate, etc. can be exemplified. Examples of the polyfunctional monomer include diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene.

[0056] As the mercapto-containing compound, alkyl-substituted mercaptan, allyl-substituted mercaptan, aryl-substituted mercaptan, hydroxyl-substituted mercaptan, alkoxy-substituted mercaptan, cyano-substituted mercaptan, amino-substituted mercaptan, silyl-substituted mercaptan, acid-substituted mercaptan, halogen-substituted mercaptan and acyl-substituted mercaptan can be mentioned. As the alkyl-substituted mercaptan, alkyl-substituted mercaptan having 1 to 20 carbon atoms is preferred, and alkyl-substituted mercaptan having 1 to 10 carbon atoms is more preferred. As the aryl-substituted mercaptan, phenyl-substituted mercaptan is preferred. As the alkoxy-substituted mercaptan, alkoxy-substituted mercaptan having 1 to 20 carbon atoms is preferred, and alkoxy-substituted mercaptan having 1 to 10 carbon atoms is more preferred. As the acid-substituted mercaptan, alkyl-substituted mercaptan having 1 to 10 carbon atoms or aryl-substituted mercaptan having 1 to 12 carbon atoms having a carboxyl group is preferred.

[0057] (Glass transition temperature of elastomer)

[0058] The glass transition temperature of the elastomer is preferably 80°C or less, more preferably 70°C or less, more preferably 60°C or less, more preferably 50°C or less, more preferably 40°C or less, more preferably 30°C or less, more preferably 20°C or less, more preferably 10°C or less, more preferably 0°C or less, more preferably -20°C or less, more preferably -40°C or less, more preferably -45°C or less, more preferably -50°C or less, more preferably -55°C or less, more preferably -60°C or less, more preferably -65°C or less, more preferably -70°C or less, more preferably -75°C or less, more preferably -80°C or less, more preferably -85°C or less, more preferably -90°C or less, more preferably -95°C or less, more preferably -100°C or less, more preferably -105°C or less, more preferably -110°C or less, more preferably -115°C or less, further preferably -120°C or less, particularly preferably -125°C or less. In this specification, "glass transition temperature" may also be referred to as "Tg". According to this structure, polymer particles (A) having a low Tg can be obtained. As a result, the printing ink composition can provide a cured film having excellent toughness. In addition, according to this structure, the viscosity of the printing ink composition can be further reduced. The Tg of the elastomer can be obtained by measuring the viscoelasticity using a flat plate composed of polymer particles (A). Specifically, Tg can be measured as follows: (1) A dynamic viscoelasticity measurement is performed on a flat plate composed of polymer particles (A) under tensile conditions using a dynamic viscoelasticity measurement device (for example, DVA-200 manufactured by IT Measurement and Control Co., Ltd.) to obtain a tanδ curve graph; (2) For the obtained tanδ curve graph, the peak temperature of tanδ is used as the glass transition temperature. Here, in the tanδ curve graph, when multiple peaks are obtained, the lowest peak temperature is used as the glass transition temperature of the elastomer.

[0059] On the other hand, since a decrease in the elastic modulus (rigidity) of the obtained cured film can be suppressed, that is, a cured film having a sufficient elastic modulus (rigidity) can be obtained, the Tg of the elastomer is preferably greater than 0°C, more preferably above 20°C, further preferably above 50°C, particularly preferably above 80°C, and most preferably above 120°C.

[0060] The Tg of the elastomer can be determined by the composition of the structural units contained in the elastomer, etc. In other words, the Tg of the obtained elastomer can be adjusted by changing the composition of the monomers used when producing (polymerizing) the elastomer.

[0061] Here, when a homopolymer is formed by polymerizing only one monomer, the group of monomers that provide a homopolymer having a Tg greater than 0°C is referred to as monomer group a. In addition, when a homopolymer is formed by polymerizing only one monomer, the group of monomers that provide a homopolymer having a Tg less than 0°C is referred to as monomer group b. An elastomer containing 50 to 100% by weight (more preferably 65 to 99% by weight) of a structural unit derived from at least one monomer selected from monomer group a and 0 to 50% by weight (more preferably 1 to 35% by weight) of a structural unit derived from at least one monomer selected from monomer group b is referred to as elastomer X. The Tg of elastomer X is greater than 0°C. In addition, when the elastomer contains elastomer X, the printing ink composition can provide a cured film having sufficient rigidity.

[0062] It is also preferable to introduce a cross-linked structure into the elastomer when the Tg of the elastomer is higher than 0° C. Examples of the method for introducing the cross-linked structure include the above-mentioned methods.

[0063] Monomers that can be included in the monomer group a are not limited to the following, for example, unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; vinyl substituted aromatic compounds such as α-methylstyrene; cycloalkylated vinyl aromatic compounds such as 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene; cycloalkoxylated vinyl aromatic compounds such as 4-methoxystyrene and 4-ethoxystyrene; ring halogenated vinyl aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; cyclic esters such as 4-acetoxystyrene Substituted vinyl aromatic compounds; ring-hydroxylated vinyl aromatic compounds such as 4-hydroxystyrene; vinyl esters such as vinyl benzoate and vinyl cyclohexanoate; vinyl halides such as vinyl chloride; aromatic monomers such as acenaphthene and indene; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and isopropyl methacrylate; aromatic methacrylates such as phenyl methacrylate; methacrylates such as isobornyl methacrylate and trimethylsilyl methacrylate; methacrylic acid monomers including methacrylic acid derivatives such as methacrylonitrile; certain acrylic acid esters such as isobornyl acrylate and tert-butyl acrylate; acrylic acid monomers including acrylic acid derivatives such as acrylonitrile, etc. Furthermore, examples of monomers that may be included in the monomer group a include monomers that can provide a homopolymer having a Tg of 120° C. or higher when forming a homopolymer, such as acrylamide, isopropyl acrylate, N-vinyl pyrrolidone, isobornyl methacrylate, dicyclopentyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate. These monomers a may be used alone or in combination of two or more.

[0064] As the above-mentioned monomer b, ethyl acrylate, butyl acrylate (also known as butyl acrylate), 2-ethylhexyl acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, etc. can be mentioned. These monomers b can be used alone or in combination of two or more. Among these monomers b, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate are particularly preferred.

[0065] (Volume average particle size of elastomer)

[0066] The volume average particle size of the elastomer is preferably 0.03 μm to 50.00 μm, more preferably 0.05 μm to 10.00 μm, more preferably 0.08 μm to 2.00 μm, further preferably 0.10 μm to 1.00 μm, further preferably 0.10 μm to 0.80 μm, and particularly preferably 0.10 μm to 0.50 μm. When the volume average particle size of the elastomer is (a) 0.03 μm or more, an elastomer having a desired volume average particle size can be stably obtained, and when it is (b) 50.00 μm or less, the heat resistance and impact resistance of the obtained cured film become good. The volume average particle size of the elastomer can be measured by using a dynamic light scattering particle size distribution measuring device or the like with an aqueous latex containing the elastomer as a sample. The method for measuring the volume average particle size of the elastomer is described in detail in the following examples.

[0067] (Ratio of elastic body)

[0068] The proportion of the elastomer in the polymer particles (A) is preferably 40 to 97% by weight, more preferably 60 to 95% by weight, and further preferably 70 to 93% by weight, when the polymer particles (A) as a whole are set to 100% by weight. When the above proportion of the elastomer is 40% by weight or more, the printing ink composition can provide a cured film with excellent toughness and impact resistance. When the above proportion of the elastomer is 97% by weight or less, the polymer particles (A) are not easy to aggregate (not easy to aggregate), so the printing ink composition will not become high viscosity. As a result, the printing ink composition can be easily handled.

[0069] (Gel content of elastomer)

[0070] The elastomer is preferably an elastomer that swells in a suitable solvent but is substantially insoluble. In addition, in order to allow the polymer microparticles (A) to exist in the form of particles in the printing ink composition and the cured film, the elastomer is preferably insoluble in the low molecular weight compound (C), the free radical polymerizable oligomer resin and the inert resin (E) described later.

[0071] The gel content of the elastomer is preferably 60 wt % or more, more preferably 80 wt % or more, further preferably 90 wt % or more, and particularly preferably 95 wt % or more. When the gel content of the elastomer is within the above range, the printing ink composition can provide a cured film with excellent toughness.

[0072] In this specification, the calculation method of gel content is as follows. First, an aqueous latex containing polymer particles (A) is obtained, and then, a powder of polymer particles (A) is obtained from the aqueous latex. There is no particular limitation on the method for obtaining a powder of polymer particles (A) from an aqueous latex, and for example, the method includes (i) agglomerating the polymer particles (A) in the aqueous latex, (ii) dehydrating the obtained agglomerates, and (iii) further drying the agglomerates to obtain a powder of polymer particles (A). Next, 2.0 g of the powder of polymer particles (A) is dissolved in 50 mL of methyl ethyl ketone (MEK). Then, the obtained MEK dissolved material is separated into components soluble in MEK (MEK soluble components) and components insoluble in MEK (MEK insoluble components). Specifically, the obtained MEK solution was centrifuged at 30,000 rpm for 1 hour using a centrifuge (manufactured by Hitachi Koki Co., Ltd., CP60E) to separate the solution into a MEK soluble component and a MEK insoluble component. Here, the centrifugation operation was performed three times in total. The weights of the obtained MEK soluble component and the MEK insoluble component were measured, and the gel content was calculated by the following formula.

[0073] Gel content (%)=(weight of methyl ethyl ketone insoluble components) / {(weight of methyl ethyl ketone insoluble components)+(weight of methyl ethyl ketone soluble components)}×100.

[0074] (2-1-2. Grafting section)

[0075] In this specification, the polymer grafted to the elastomer is referred to as a graft portion. The graft portion contains a polymer, which contains structural units from one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylate monomers as structural units. Since the graft portion has the above-mentioned structure, it can play various roles. "Various roles" include (a) improving the compatibility between the resin component in the printing ink composition and the polymer particles (A), (b) improving the dispersibility of the polymer particles (A) in the printing ink composition and in the cured film, and (c) the polymer particles (A) can be dispersed in the printing ink composition and the cured film in the state of primary particles.

[0076] Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene.

[0077] Specific examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile.

[0078] Specific examples of the (meth)acrylate monomer include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, and hydroxybutyl (meth)acrylate.

[0079] One or more monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylate monomers may be used alone or in combination of two or more.

[0080] In the grafted portion, as structural units, the total of structural units derived from aromatic vinyl monomers, structural units derived from vinyl cyanide monomers, and structural units derived from (meth)acrylate monomers preferably comprises 10 to 95% by weight, more preferably 30 to 92% by weight, further preferably 50 to 90% by weight, particularly preferably 60 to 87% by weight, and most preferably 70 to 85% by weight in 100% by weight of all structural units.

[0081] The grafted portion preferably contains a structural unit derived from a monomer having a reactive group as a structural unit. The monomer having the reactive group is preferably selected from an epoxy group, an oxetane group, a hydroxyl group, an amino group, an imide group, a carboxylic acid group, a carboxylic anhydride group, a cyclic ester, a cyclic amide, a benzoic acid group, a The monomer having one or more reactive groups selected from the group consisting of an oxazine group and a cyanate group is more preferably a monomer having one or more reactive groups selected from the group consisting of an epoxy group, a hydroxyl group and a carboxylic acid group, and the most preferred monomer having an epoxy group. According to the above constitution, in the obtained printing ink composition, the grafted part of the polymer microparticles (A) can be chemically bonded to the low molecular weight compound (C) or the radical polymerizable oligomer resin and the inert resin (E). As a result, in the obtained printing ink composition or the cured film, the polymer microparticles (A) can be maintained in a good dispersion state without agglomerating the polymer microparticles (A).

[0082] Specific examples of the monomer having an epoxy group include glycidyl group-containing vinyl monomers such as glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and allyl glycidyl ether.

[0083] Specific examples of monomers having a hydroxyl group include (a) hydroxyl straight-chain alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate (particularly C1-6 hydroxyl straight-chain alkyl (meth)acrylate); (b) caprolactone-modified hydroxy (meth)acrylates; (c) hydroxyl branched alkyl (meth)acrylates such as methyl α-(hydroxymethyl)acrylate and ethyl α-(hydroxymethyl)acrylate; (d) hydroxyl-containing (meth)acrylates such as mono(meth)acrylates of polyester diols (particularly saturated polyester diols) obtained from dicarboxylic acids (phthalic acid, etc.) and diols (propylene glycol, etc.);

[0084] Specific examples of the monomer having a carboxylic acid group include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid. As the monomer having a carboxylic acid group, the above monocarboxylic acids can be preferably used.

[0085] The above-mentioned monomers having a reactive group may be used alone or in combination of two or more.

[0086] The grafted portion preferably contains 0.5 to 90% by weight of a structural unit derived from a monomer having a reactive group in 100% by weight of the grafted portion, more preferably 1 to 50% by weight, further preferably 2 to 35% by weight, and particularly preferably 3 to 20% by weight. When the grafted portion contains 0.5% by weight or more of a structural unit derived from a monomer having a reactive group in 100% by weight of the grafted portion, the printing ink composition can provide a cured film having sufficient impact resistance. When the grafted portion contains 90% by weight or less of a structural unit derived from a monomer having a reactive group in 100% by weight of the grafted portion, the printing ink composition has the advantages of being able to provide a cured film having sufficient impact resistance and having good storage stability.

[0087] The structural unit derived from the monomer having a reactive group is preferably contained in the graft portion, and more preferably contained only in the graft portion.

[0088] The graft portion may contain a structural unit derived from a polyfunctional monomer as a structural unit. When the graft portion contains a structural unit derived from a polyfunctional monomer, there are the following advantages: (a) swelling of the polymer microparticles (A) can be prevented in the printing ink composition, (b) the viscosity of the printing ink composition is reduced, so there is a tendency for the handling of the printing ink composition to be improved, and (c) the dispersibility of the polymer microparticles (A) in the printing ink composition is improved.

[0089] When the graft portion does not contain a structural unit derived from a polyfunctional monomer, the printing ink composition can provide a cured film having better toughness and impact resistance than when the graft portion contains a structural unit derived from a polyfunctional monomer.

[0090] As the multifunctional monomer that can be used for the polymerization of the graft portion, the same monomers as those mentioned above can be cited. Among these multifunctional monomers, as the multifunctional monomer that can be preferably used for the polymerization of the graft portion, allyl methacrylate, butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and polyethylene glycol di(meth)acrylates can be cited. These multifunctional monomers can be used alone or in combination of two or more.

[0091] The graft portion preferably contains 1 to 20% by weight, more preferably 5 to 15% by weight, of the structural unit derived from the polyfunctional monomer based on 100% by weight of the graft portion.

[0092] In the polymerization of the graft part, the above-mentioned monomers may be used alone or in combination of two or more.

[0093] The graft portion may contain, as a structural unit, a structural unit derived from other monomers in addition to the structural unit derived from the above-mentioned monomers.

[0094] (Glass transition temperature of grafted portion)

[0095] The glass transition temperature of the grafted portion is preferably 190°C or less, more preferably 160°C or less, more preferably 140°C or less, more preferably 120°C or less, preferably 80°C or less, more preferably 70°C or less, more preferably 60°C or less, more preferably 50°C or less, more preferably 40°C or less, more preferably 30°C or less, more preferably 20°C or less, more preferably 10°C or less, more preferably 0°C or less, more preferably -20°C or less, more preferably -40°C or less, more preferably -45°C or less, more preferably - The temperature of the present invention is preferably below -50°C, more preferably below -55°C, more preferably below -60°C, more preferably below -65°C, more preferably below -70°C, more preferably below -75°C, more preferably below -80°C, more preferably below -85°C, more preferably below -90°C, more preferably below -95°C, more preferably below -100°C, more preferably below -105°C, more preferably below -110°C, more preferably below -115°C, further preferably below -120°C, and particularly preferably below -125°C.

[0096] The glass transition temperature of the grafted portion is preferably 0°C or higher, more preferably 30°C or higher, more preferably 50°C or higher, more preferably 70°C or higher, further preferably 90°C or higher, and particularly preferably 110°C or lower.

[0097] The Tg of the grafted portion can be determined by the composition of the structural unit contained in the grafted portion, etc. In other words, the Tg of the obtained grafted portion can be adjusted by changing the composition of the monomer used when producing (polymerizing) the grafted portion.

[0098] The Tg of the grafted portion can be obtained by measuring the viscoelasticity using a flat plate composed of polymer particles (A). Specifically, the Tg can be measured as follows: (1) Using a dynamic viscoelasticity measuring device (e.g., DVA-200 manufactured by IT Instrumentation and Control Co., Ltd.) on a flat plate composed of polymer particles (A), dynamic viscoelasticity is measured under stretching conditions to obtain a tanδ curve; (2) In the obtained tanδ curve, the peak temperature of tanδ is used as the glass transition temperature. Here, in the tanδ curve, when multiple peaks are obtained, the highest peak temperature is used as the glass transition temperature of the grafted portion.

[0099] (Grafting rate of grafted part)

[0100] In one embodiment of the present invention, the polymer microparticles (A) are polymers having the same structure as the grafted portion, and may have polymers that are not grafted and bonded to the elastomer. In this specification, a polymer having the same structure as the grafted portion and not grafted and bonded to the elastomer is referred to as a non-grafted polymer. The non-grafted polymer also constitutes a part of the polymer microparticles (A) involved in one embodiment of the present invention. The above-mentioned non-grafted polymer can also be said to be a polymer that is not grafted and bonded to the elastomer in the polymer produced in the polymerization of the grafted portion.

[0101] In this specification, the ratio of the polymer grafted to the elastomer in the polymer produced by the polymerization of the grafted portion is called the grafting ratio. The grafting ratio can also be said to be a value represented by (weight of the grafted portion) / {(weight of the grafted portion)+(weight of the non-grafted polymer)}×100.

[0102] The grafting rate of the grafted portion is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. When the grafting rate is 70% or more, there is an advantage that the viscosity of the printing ink composition does not become too high.

[0103] In this specification, the method for calculating the grafting rate is as follows. First, an aqueous latex containing polymer particles (A) is obtained, and then, a powder of polymer particles (A) is obtained from the aqueous latex. As a method for obtaining a powder of polymer particles (A) from an aqueous latex, specifically, there can be cited a method of (i) coagulating the polymer particles (A) in the above-mentioned aqueous latex, (ii) dehydrating the obtained coagulant, and (iii) further drying the coagulant to obtain a powder of polymer particles (A). Next, 2 g of the powder of polymer particles (A) is dissolved in 50 mL of methyl ethyl ketone (MEK). Then, the obtained MEK dissolved material is separated into a component soluble in MEK (MEK soluble component) and a component insoluble in MEK (MEK insoluble component). Specifically, the obtained MEK dissolved substance was centrifuged for 1 hour at a speed of 30000rpm using a centrifugal separator (manufactured by Hitachi Koki Co., Ltd., CP60E), and the dissolved substance was separated into a MEK soluble component and a MEK insoluble component. Here, the centrifugal separation operation was implemented in three groups in total. Then, 20 ml of the concentrated MEK soluble component was mixed with 200 ml of methanol. A calcium chloride aqueous solution obtained by dissolving 0.01 g of calcium chloride in water was added to the obtained mixture, and the obtained mixture was stirred for 1 hour. Then, the obtained mixture was separated into a methanol soluble component and a methanol insoluble component, and the weight of the methanol insoluble component was used as the free polymer (FP) amount.

[0104] The grafting rate was calculated according to the following formula.

[0105] Grafting rate (%)=100-[(FP amount) / {(FP amount)+(weight of MEK insoluble component)}] / (weight of polymer at grafted portion)×10,000.

[0106] It should be noted that the weight of the polymer outside the graft portion is the feed amount of the monomers constituting the polymer outside the graft portion. The polymer outside the graft portion is, for example, an elastomer. In addition, when the polymer particles (A) include the surface cross-linked polymer described later, the polymer outside the graft portion includes both the elastomer and the surface cross-linked polymer. The weight of the polymer in the graft portion is the feed amount of the monomers constituting the polymer in the graft portion. In addition, in the calculation of the grafting rate, the method of coagulating the polymer particles (A) is not particularly limited, and a method using a solvent, a method using a coagulant, a method of spraying an aqueous latex, etc. can be used.

[0107] In the production of polymer microparticles (A), when the elastomer and the graft part are polymerized sequentially, in the obtained polymer microparticles (A), at least a part of the graft part may be covered with at least a part of the elastomer. In other words, sequential polymerization of the elastomer and the graft part can also be referred to as multi-stage polymerization of the elastomer and the graft part. The polymer microparticles (A) obtained by multi-stage polymerization of the elastomer and the graft part can also be referred to as multi-stage polymers.

[0108] When the polymer microparticles (A) are multistage polymers, the grafted portion may cover at least a portion of the elastomer or the entire elastomer. When the polymer microparticles (A) are multistage polymers, a portion of the grafted portion may enter the inside of the elastomer.

[0109] When the polymer particles (A) are multistage polymers, the elastomer and the grafted portion may also form a layer structure. For example, a method in which the elastomer forms the innermost layer (also referred to as the core layer) and the layer of the grafted portion is formed on the outside of the elastomer as the outermost layer (also referred to as the shell layer) is also a method of the present invention. A structure in which the elastomer is the core layer and the grafted portion is the shell layer may also be called a core-shell structure. In this way, the polymer particles (A) in which the elastomer and the grafted portion form a layer structure (core-shell structure) may also be referred to as a multilayer polymer or a core-shell polymer. That is, in one embodiment of the present invention, the polymer particles (A) may be a multistage polymer and / or a multilayer polymer or a core-shell polymer. However, as long as the grafted portion is graft-bonded to the elastomer, the polymer particles (A) are not limited to the above-mentioned structure.

[0110] It is preferred that at least a part of the grafted portion covers at least a part of the elastomer. In other words, it is preferred that at least a part of the grafted portion is present on the outermost side of the polymer fine particle (A).

[0111] (2-1-3. Surface cross-linked polymer)

[0112] In the rubber-containing graft copolymer, in addition to the elastomer and the grafted portion graft-bonded to the elastomer, it is preferred to further have a surface cross-linked polymer. In other words, in the polymer particles (A), in addition to the elastomer and the grafted portion graft-bonded to the elastomer, it is preferred to further have a surface cross-linked polymer. Hereinafter, an embodiment of the present invention is described by taking the case where the polymer particles (A) (e.g., the rubber-containing graft copolymer) further have a surface cross-linked polymer as an example. In this case, there are the following advantages: (a) in the manufacture of the polymer particles (A), the anti-blocking property can be improved, and (b) the dispersibility of the polymer particles (A) in the printing ink composition becomes better. As a reason, there is no particular limitation, but it can be inferred as follows: by coating at least a portion of the elastomer with a surface cross-linked polymer, the exposure of the elastomer portion of the polymer particles (A) is reduced, and as a result, the elastomers are not easily adhered to each other, so the dispersibility of the polymer particles (A) is improved.

[0113] When the polymer particles (A) further have a surface crosslinked polymer, the following effects may be further achieved: (a) reducing the viscosity of the printing ink composition, (b) increasing the crosslinking density in the elastomer, and (c) increasing the grafting efficiency of the grafted portion. The crosslinking density in the elastomer refers to the number of crosslinked structures in the entire elastomer.

[0114] The surface cross-linked polymer is composed of a polymer containing 30 to 100% by weight of a structural unit derived from a polyfunctional monomer and 0 to 70% by weight of a structural unit derived from other vinyl monomers as structural units, with the total amount being 100% by weight.

[0115] As a multifunctional monomer that can be used for the polymerization of surface cross-linked polymers, the same monomers as the above-mentioned multifunctional monomers can be cited. Among these multifunctional monomers, as a multifunctional monomer that can be preferably used for the polymerization of surface cross-linked polymers, allyl methacrylate, ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate (such as dimethacrylate 1,3-butylene glycol ester, etc.), butanediol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate and polyethylene glycol di(meth)acrylate can be cited. These multifunctional monomers can be used alone or in combination of two or more.

[0116] The polymer particles (A) may include a surface crosslinked polymer independently polymerized with the rubber-containing graft copolymer, or may include a surface crosslinked polymer polymerized with the rubber-containing graft copolymer. The polymer particles (A) may be a multistage polymer obtained by sequentially polymerizing the elastomer, the surface crosslinked polymer, and the graft portion in multiple stages. In any of these embodiments, the surface crosslinked polymer may cover at least a portion of the elastomer.

[0117] The surface cross-linked polymer can also be regarded as a part of the elastomer. In other words, the surface cross-linked polymer can also be regarded as a part of the rubber-containing graft copolymer, also known as the surface cross-linked polymer portion. In the case where the polymer particles (A) contain a surface cross-linked polymer, the graft portion can be (a) graft-bonded to an elastomer other than the surface cross-linked polymer, (b) graft-bonded to the surface cross-linked polymer, or (c) graft-bonded to both the elastomer other than the surface cross-linked polymer and the surface cross-linked polymer. In the case where the polymer particles (A) contain a surface cross-linked polymer, the volume average particle size of the above-mentioned elastomer refers to the volume average particle size of the elastomer containing the surface cross-linked polymer.

[0118] The case (case D) in which the polymer microparticles (A) are a multistage polymer obtained by sequentially multistage polymerization of an elastomer, a surface cross-linked polymer, and a grafted portion is described. In case D, the surface cross-linked polymer may be coated with a portion of the elastomer or the entire elastomer. In case D, sometimes a portion of the surface cross-linked polymer enters the inside of the elastomer. In case D, the grafted portion may be coated with a portion of the surface cross-linked polymer or the entire surface cross-linked polymer. In case D, sometimes a portion of the grafted portion enters the inside of the surface cross-linked polymer. In case D, the elastomer, the surface cross-linked polymer, and the grafted portion may have a layer structure. For example, a method in which the elastomer is the innermost layer (core layer), the layer of the surface cross-linked polymer is present on the outside of the elastomer as an intermediate layer, and the layer of the grafted portion is present on the outside of the surface cross-linked polymer as the outermost layer (shell layer) is also one method of the present invention.

[0119] (2-1-4. Physical properties of polymer microparticles (A))

[0120] The physical properties of the polymer fine particles (A) are described below.

[0121] (Volume Average Particle Size (Mv) of Polymer Microparticles (A))

[0122] From the viewpoint of obtaining a printing ink composition having a desired viscosity and being highly stable, the volume average particle size (Mv) of the polymer microparticles (A) is preferably 0.03 μm to 50.00 μm, more preferably 0.05 μm to 10.00 μm, more preferably 0.08 μm to 2.00 μm, further preferably 0.10 μm to 1.00 μm, further preferably 0.10 μm to 0.80 μm, and particularly preferably 0.10 μm to 0.50 μm. When the volume average particle size (Mv) of the polymer microparticles (A) is within the above range, there is also an advantage that the dispersibility of the polymer microparticles (A) in the printing ink composition is good. It should be noted that, in this specification, unless otherwise specified, the "volume average particle size (Mv) of the polymer microparticles (A)" refers to the volume average particle size of the primary particles of the polymer microparticles (A). The volume average particle size of the polymer microparticles (A) can be measured using a dynamic light scattering particle size distribution measuring device or the like using an aqueous latex containing the polymer microparticles (A) as a sample. The volume average particle size of the polymer microparticles (A) is described in detail in the following examples. The volume average particle size of the polymer microparticles (A) can also be measured by cutting a cured film of the printing ink composition, photographing the cut surface using an electron microscope or the like, and using the obtained photographed data (photographed image).

[0123] The number distribution of the volume average particle size of the polymer microparticles (A) preferably has a half-peak width of 0.5 to 1 times the volume average particle size from the viewpoint of obtaining a printing ink composition that has a low viscosity and is easy to handle.

[0124] (2-1-5. Method for producing polymer microparticles (A))

[0125] The polymer microparticles (A) can be produced by, after polymerizing an elastomer, graft-polymerizing a polymer constituting a graft portion onto the elastomer in the presence of the elastomer. Hereinafter, the method for producing the polymer microparticles (A) (polymerization method) will be described by taking as an example the method for producing an aqueous latex of the polymer microparticles (A) which can be preferably used in the production of the present printing ink composition described later.

[0126] The polymer particles (A) can be manufactured by known methods, such as emulsion polymerization, suspension polymerization, microsuspension polymerization, etc. Specifically, the polymerization of the elastomer in the polymer particles (A), the polymerization of the grafted portion (graft polymerization), and the polymerization of the surface cross-linked polymer can be implemented by known methods, such as emulsion polymerization, suspension polymerization, microsuspension polymerization, etc. Among them, as a method for manufacturing polymer particles (A), emulsion polymerization is particularly preferred. According to the emulsion polymerization method, there are the following advantages: (a) the composition design of the polymer particles (A) is easy, (b) the industrial production of the polymer particles (A) is easy, and (c) it is easy to obtain an aqueous latex of the polymer particles (A) that can be preferably used for the manufacture of a printing ink composition. Below, the elastomer that can be contained in the polymer particles (A), the grafted portion, and the method for manufacturing the surface cross-linked polymer as an arbitrary structure are described.

[0127] (Method for producing elastomer)

[0128] Consider the case where the elastomer contains at least one selected from diene rubber and (meth)acrylate rubber. In this case, the elastomer can be produced by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, etc., and as its production method, for example, the method described in WO2005 / 028546 can be used.

[0129] Consider the case where the elastomer includes an organosiloxane rubber. In this case, the elastomer can be produced by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, etc., and as its production method, for example, the method described in WO2006 / 070664 can be used.

[0130] (Method for producing grafted portion)

[0131] The graft portion can be formed, for example, by polymerizing the monomers used to form the graft portion by known free radical polymerization. In the case where (a) the elastomer or (b) the polymer particle precursor comprising the elastomer and the surface cross-linked polymer is obtained in the form of an aqueous latex, the polymerization of the graft portion is preferably carried out by emulsion polymerization. The graft portion can be manufactured, for example, by the method described in WO2005 / 028546.

[0132] The grafted part is composed of a plurality of grafted parts (e.g., grafted part 1, grafted part 2, ..., grafted part n ) is described below. In this case, the grafted portion 1, the grafted portion 2, ..., the grafted portion n The above methods are used to polymerize each of the above-mentioned grafted parts, and then the grafted parts are mixed and composited to produce a grafted part (composite) composed of multiple grafted parts. Alternatively, grafted part 1, grafted part 2, ..., grafted part n The multi-stage polymerization is sequentially performed to produce a single graft portion composed of a plurality of graft portions.

[0133] (Method for producing surface cross-linked polymer)

[0134] The surface cross-linked polymer can be formed by polymerizing monomers for forming the surface cross-linked polymer by known free radical polymerization. When the elastomer is obtained in the form of an aqueous latex, the polymerization of the surface cross-linked polymer is preferably performed by emulsion polymerization.

[0135] When an emulsion polymerization method is used as a method for producing the polymer fine particles (A), a known emulsifier (dispersant) can be used for the production of the polymer fine particles (A).

[0136] As emulsifiers, for example, anionic emulsifiers, nonionic emulsifiers, polyvinyl alcohol, alkyl-substituted cellulose, polyvinyl pyrrolidone, polyacrylic acid derivatives, etc. can be mentioned. As anionic emulsifiers, sulfur-based emulsifiers, phosphorus-based emulsifiers, sarcosine-based emulsifiers, carboxylic acid-based emulsifiers, etc. can be mentioned. As sulfur-based emulsifiers, sodium dodecylbenzene sulfonate (abbreviated as: SDBS) can be mentioned. As phosphorus-based emulsifiers, sodium polyoxyethylene lauryl ether phosphate can be mentioned.

[0137] As a method for producing polymer microparticles (A), when an emulsion polymerization method is used, a thermal decomposition type initiator can be used in the production of polymer microparticles (A). As the above-mentioned thermal decomposition type initiator, for example, known initiators such as (a) 2,2'-azobisisobutyronitrile and (b) peroxides such as organic peroxides and inorganic peroxides can be mentioned. As the above-mentioned organic peroxide, tert-butyl peroxyisopropyl carbonate, terpene hydroperoxide, isopropylbenzene hydroperoxide, diisopropylbenzene peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide and tert-hexyl peroxide can be mentioned. As the above-mentioned inorganic peroxide, hydrogen peroxide, potassium persulfate, ammonium persulfate, etc. can be mentioned.

[0138] In the manufacture of polymer particles (A), a redox initiator can also be used. The redox initiator is an initiator that combines (a) a peroxide such as an organic peroxide and an inorganic peroxide with (b) a reducing agent such as a transition metal salt such as iron (II) sulfate, sodium formaldehyde sulfoxylate, glucose, etc. In addition, a chelating agent such as disodium ethylenediaminetetraacetate can be used in combination as needed, and further a phosphorus-containing compound such as sodium pyrophosphate can be used in combination as needed.

[0139] When a redox initiator is used, polymerization can be carried out even at a low temperature where the above-mentioned peroxide does not substantially undergo thermal decomposition, and the polymerization temperature can be set within a wide range. Therefore, it is preferred to use a redox initiator. Among the redox initiators, organic peroxides such as cumene hydroperoxide, dicumyl peroxide, terpene hydroperoxide and tert-butyl hydroperoxide are preferably used as redox initiators of peroxides. The amount of the above-mentioned initiator used and the amount of the above-mentioned reducing agent, transition metal salt and chelating agent used when the redox initiator is used can be used within a known range.

[0140] For the purpose of introducing a crosslinked structure into an elastomer, a grafted portion or a surface crosslinked polymer, when a multifunctional monomer is used in the polymerization of the elastomer, the grafted portion or the surface crosslinked polymer, a known chain transfer agent can be used within the scope of a known usage amount. By using a chain transfer agent, the molecular weight and / or the degree of crosslinking of the obtained elastomer, the grafted portion or the surface crosslinked polymer can be easily adjusted.

[0141] In the production of polymer microparticles (A), a surfactant may be used in addition to the above-mentioned components. The type and amount of the surfactant used are within a known range.

[0142] In the production of the polymer microparticles (A), conditions in known numerical ranges can be appropriately applied as to the polymerization temperature, pressure, deoxygenation and other conditions during the polymerization.

[0143] It should be noted that in the present printing ink composition, the content of the polymer microparticles (A) is preferably 1.0 wt % or more, more preferably 1.5 wt % or more, further preferably 2.0 wt % or more, and particularly preferably 2.5 wt % or more relative to 100 wt % of the UV curable printing ink composition. This configuration has the advantage of excellent adhesion of the cured film to the substrate.

[0144] In addition, in the present printing ink composition, the content of the polymer microparticles (A) is preferably 10.0 wt % or less, more preferably 8.0 wt % or less, further preferably 6.0 wt % or less, and particularly preferably 4.0 wt % or less, relative to 100 wt % of the UV curable printing ink composition. This configuration has the advantage of being able to maintain the cured film in a high hardness state.

[0145] (2-2. Resin (B))

[0146] The present printing ink composition preferably further comprises a resin (B). The resin (B) is preferably contained in the powder of the polymer particles (A) described later. In other words, the powder of the polymer particles (A) preferably comprises the resin (B). According to this configuration, there is a surprising advantage that the polymer particles (A) have excellent dispersibility in the printing ink composition.

[0147] The resin (B) may be, for example, a thermosetting resin, a thermoplastic resin, or any combination of a thermosetting resin and a thermoplastic resin.

[0148] (2-2-1. Thermosetting resin)

[0149] The thermosetting resin in the resin (B) is not particularly limited, but preferably includes at least one selected from epoxy resins, phenolic resins, polyol resins, and amino-formaldehyde resins. The thermosetting resin in the resin (B) may also include a resin containing a polymer obtained by polymerizing an aromatic polyester raw material. In the resin (B), only one type of thermosetting resin may be used, or two or more types may be used in combination.

[0150] (Epoxy resin)

[0151] The epoxy resin is not particularly limited as long as it has at least one epoxy group in the molecule.

[0152] Specific examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, bisphenol S type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, novolac type epoxy resins, glycidyl ether type epoxy resins of bisphenol A propylene oxide adducts, hydrogenated bisphenol A (or F) type epoxy resins, fluorinated epoxy resins, rubber-modified epoxy resins containing polybutadiene or NBR, flame-retardant epoxy resins such as glycidyl ether of tetrabromobisphenol A, p-oxybenzoic acid glycidyl ether ester type epoxy resins, meta-aminophenol type epoxy resins, diaminodiphenylmethane type epoxy resins, urethane-modified epoxy resins having urethane bonds, various alicyclic epoxy resins, glycidyl ethers of polyols, hydantoin type epoxy resins, epoxides of unsaturated polymers such as petroleum resins, and amino group-containing glycidyl ether resins. Examples of the polyol include N,N-diglycidylaniline, N,N-diglycidyl-o-toluidine, triglycidyl isocyanurate, polyalkylene glycol diglycidyl ether, and glycerol. Examples of the epoxy resin include epoxy compounds obtained by addition reaction of bisphenol A (or F) or polyacids with the above-mentioned epoxy resins. The epoxy resin is not limited to these, and commonly used epoxy resins can be used. These epoxy resins can be used alone or in combination of two or more.

[0153] In view of high reactivity during curing of the printing ink composition and the easy formation of a three-dimensional network in the obtained cured film, the above-mentioned epoxy resin preferably has at least two epoxy groups in one molecule. In addition, as the epoxy resin, in view of economical efficiency and easy availability, an epoxy resin having at least two epoxy groups in one molecule is preferably an epoxy resin having a bisphenol type epoxy resin as a main component.

[0154] (Phenolic resin)

[0155] The phenolic resin is not particularly limited as long as it is a compound obtained by the reaction of phenols and aldehydes. As phenols, there are no particular limitations, and examples thereof include phenol, o-cresol, m-cresol, p-cresol, xylenol, p-tert-butylphenol, p-octylphenol, p-phenylphenol, bisphenol A, bisphenol F, and resorcinol. As particularly preferred phenols, phenol and cresol can be mentioned.

[0156] The aldehydes are not particularly limited, and examples thereof include formaldehyde, acetaldehyde, butyraldehyde, acrolein, and mixtures thereof. As the aldehydes, substances that are sources of the above-mentioned aldehydes or solutions of these aldehydes may also be used. As the aldehydes, formaldehyde is preferred from the perspective of ease of handling when phenols react with aldehydes.

[0157] The molar ratio (F / R) of phenols (P) to aldehydes (R) when reacting phenols with aldehydes (hereinafter also referred to as the reaction molar ratio) is not particularly limited. When an acid catalyst is used in the reaction, the above reaction molar ratio (F / R) is preferably 0.4 to 1.0, and more preferably 0.5 to 0.8. When an alkali catalyst is used in the reaction, the above reaction molar ratio (F / R) is preferably 0.4 to 4.0, and more preferably 0.8 to 2.5. When the reaction molar ratio is above the above lower limit, the yield will not become too low, and the molecular weight of the obtained phenolic resin will not become small. On the other hand, when the reaction molar ratio is below the above upper limit, the molecular weight of the phenolic resin will not become too large, and the softening point will not become too high, so sufficient fluidity can be obtained when heated. In addition, when the reaction molar ratio is below the above upper limit, it is easy to control the molecular weight, and gelation or partial gelation caused by the reaction conditions will not occur.

[0158] (Polyol resin)

[0159] The polyol resin is a compound having two or more active hydrogen atoms at the terminal, and is a difunctional or higher polyol having a molecular weight of about 50 to 20000. Examples of the polyol resin include aliphatic alcohols, aromatic alcohols, polyether polyols, polyester polyols, polyolefin polyols, and acrylic polyols.

[0160] The aliphatic alcohol may be any of a diol or a trihydric or higher alcohol (a triol, a tetrahydric alcohol, etc.). Examples of the diol include (a) ethylene glycol, propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol and other alkylene glycols (particularly alkylene glycols having 1 to 6 carbon atoms), and (b) dehydrated condensates of two or more molecules (e.g., about 2 to 6 molecules) of the alkylene glycol compounds (diethylene glycol, dipropylene glycol, tripropylene glycol, etc.). Examples of the triol include glycerol, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol and the like (particularly trihydric alcohols having 3 to 10 carbon atoms). Examples of the tetrahydric alcohol include pentaerythritol, diglycerol and the like. In addition, sugars such as monosaccharides, oligosaccharides, and polysaccharides can be mentioned.

[0161] Examples of the aromatic alcohol include bisphenols such as bisphenol A and bisphenol F; biphenyls such as dihydroxybiphenyl; polyphenols such as hydroquinone and phenol formaldehyde condensate; and naphthalene diol.

[0162] Examples of polyether polyols include (a) random copolymers or block copolymers obtained by ring-opening polymerization of ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc. in the presence of one or more initiators containing active hydrogen, and (b) mixtures of these copolymers. Examples of initiators containing active hydrogen used in the ring-opening polymerization of polyether polyols include glycols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and bisphenol A; triols such as trimethylolethane, trimethylolpropane, and glycerol; sugars such as monosaccharides, oligomers, and polysaccharides; amines such as sorbitol, ammonia, ethylenediamine, urea, monomethyldiethanolamine, and monoethyldiethanolamine; and the like.

[0163] As polyester polyols, for example, there can be mentioned polymers obtained by polycondensing a polyacid and / or an anhydride of a polyacid with a polyol in the presence of an esterification catalyst within a temperature range of 150 to 270°C. As the above-mentioned polyacid, there can be mentioned maleic acid, fumaric acid, adipic acid, sebacic acid, phthalic acid, dodecanedioic acid, isophthalic acid, azelaic acid, etc. As the above-mentioned polyols, there can be mentioned ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, etc. In addition, as polyester polyols, there can be mentioned (a) ring-opening polymers such as ε-caprolactone and valerolactone, and (b) active hydrogen compounds having two or more active hydrogens such as polycarbonate diol and castor oil.

[0164] Examples of the polyolefin polyol include polybutadiene polyol, polyisoprene polyol, and hydrogenated products thereof.

[0165] Examples of acrylic polyols include copolymers of (a) hydroxyl-containing monomers such as hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate and vinylphenol and (b) general-purpose monomers such as n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate, and mixtures of these copolymers.

[0166] Among these polyol resins, polyether polyols are preferred because the printing ink composition has low viscosity and excellent workability, and can provide a cured film with excellent balance between hardness and toughness. In addition, polyester polyols are preferred because the printing ink composition can provide a cured film with excellent adhesion.

[0167] (Amino-formaldehyde resin)

[0168] The amino-formaldehyde resin is not particularly limited as long as it is a compound obtained by reacting an amino compound with an aldehyde under a basic catalyst. Examples of the amino compound include melamine; 6-substituted guanamines such as guanamine, acetylguanamine, and benzoguanamine; amine-substituted triazine compounds such as CTUguanamine (3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl)ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane) and CMTUguanamine (3,9-bis[(3,5-diamino-2,4,6-triazaphenyl)methyl]-2,4,8,10-tetraoxaspiro[5,5]undecane); and ureas such as urea, thiourea, and ethyleneurea. In addition, as the above-mentioned amino compound, the following may be used: (a) substituted melamine compounds obtained by substituting the hydrogen of the amino group of melamine with an alkyl group, an alkenyl group and / or a phenyl group (described in the specification of U.S. Pat. No. 5,998,573 (corresponding to the Japanese publication: Japanese Patent Laid-Open No. 9-143238)), and (b) substituted melamine compounds obtained by substituting the hydrogen of the amino group of melamine with a hydroxyalkyl group, a hydroxyalkyloxyalkyl group, and / or an aminoalkyl group (described in the specification of U.S. Pat. No. 5,322,915 (corresponding to the Japanese publication: Japanese Patent Laid-Open No. 5-202157)). As the above-mentioned amino compound, from the perspective of industrial production and low price, melamine, guanamine, acetylguanamine and benzoguanamine, which are polyfunctional amino compounds, are preferred among the above-mentioned compounds, and melamine is particularly preferred. The above-mentioned amino compounds may be used alone or in combination of two or more. In addition to these amino compounds, (a) phenols such as phenol, cresol, alkylphenol, resorcinol, hydroquinone, and pyrogallol, and (b) aniline may be additionally used.

[0169] Examples of the aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, and furfural. As the aldehydes, formaldehyde and paraformaldehyde are preferred because they are low in price and have good reactivity with the amino compounds mentioned above. In the manufacture of the amino-formaldehyde resin, the aldehydes are preferably used in an amount of 1.1 to 6.0 moles per effective aldehyde group relative to 1 mole of the amino compound, and particularly preferably 1.2 to 4.0 moles.

[0170] (Aromatic polyester raw materials)

[0171] Examples of the aromatic polyester raw material include aromatic vinyl compounds, (meth)acrylic acid derivatives, vinyl cyanide compounds, radical polymerizable monomers such as maleimide compounds, dimethyl terephthalate, alkylene glycol, etc. In the present specification, (meth)acrylic acid refers to acrylic acid and / or methacrylic acid.

[0172] The thermosetting resin in the resin (B) is a thermosetting resin obtained by polymerization of an ethylenically unsaturated monomer with a reactive group (e.g., an epoxy group, an oxetane group, a hydroxyl group, an amino group, an imide group, a carboxylic acid group, a carboxylic anhydride group, a cyclic ester, a cyclic amide, a benzoic acid group) by a method other than radical polymerization. The compounds obtained by bonding an ethylenically unsaturated monomer to a compound having a reactive group (such as an oxazine group and a cyanate group) also include compounds having at least one ethylenically unsaturated bond in the molecule. In this specification, "a compound obtained by bonding an ethylenically unsaturated monomer to a compound having a reactive group by a method other than free radical polymerization" is sometimes referred to as "a monomer containing a reactive group-ethylenically unsaturated bond". The thermosetting resin in the resin (B) also includes a monomer containing a reactive group-ethylenically unsaturated bond.

[0173] The compound having a reactive group also includes thermosetting resins such as resins containing polymers obtained by polymerizing the above-mentioned epoxy resins, phenolic resins, polyol resins, amino-formaldehyde resins and aromatic polyester raw materials. The monomer containing a reactive group-ethylenically unsaturated bond may be a compound obtained by bonding an ethylenically unsaturated monomer to one or more polymers selected from epoxy resins, phenolic resins, polyol resins, amino-formaldehyde resins and aromatic polyester raw materials by a method other than free radical polymerization.

[0174] Examples of the monomer containing an ethylenically unsaturated bond as a reactive group include unsaturated polyester resins, vinyl ester resins, epoxy acrylates, etc. These may be used alone or in combination of two or more.

[0175] (2-2-2. Thermoplastic resin)

[0176] Examples of the thermoplastic resin in the resin (B) include acrylic polymers, vinyl copolymers, polycarbonates, polyamides, polyesters, polyphenylene ethers, polyurethanes, and polyvinyl acetates, etc. These may be used alone or in combination of two or more.

[0177] Acrylic polymers are polymers having as main components structural units composed of acrylic ester monomers. The number of carbon atoms in the ester portion of the acrylic ester monomers is preferably 1 to 20. In addition, acrylic polymers include (a) homopolymers of acrylic ester monomers, (b) copolymers of acrylic ester monomers and monomers such as unsaturated fatty acids, acrylamide monomers, maleimide monomers, vinyl acetate, or vinyl copolymers (hereinafter also referred to as acrylic copolymers), and the like.

[0178] Examples of the acrylic acid ester monomer include methyl acrylate (MA), ethyl acrylate (EA), 2-ethylhexyl acrylate (2EHA), acrylic acid (AA), methacrylic acid (MAA), 2-hydroxyethyl acrylate (2HEA), 2-hydroxyethyl methacrylate (2HEMA), butyl acrylate (BA), methyl methacrylate (MMA), ethyl methacrylate (EMA), n-butyl methacrylate (nBMA), isobutyl methacrylate (iBMA), propyl acrylate, isopropyl acrylate, isobutyl acrylate, tert-butyl acrylate, neopentyl acrylate, isodecyl acrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate, cyclohexyl acrylate, isobornyl acrylate, tricyclodecanyl acrylate, hydroxyethyl acrylate, hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxyethyl acrylate, 2-methoxyethyl acrylate, dimethylaminoethyl acrylate, chloroethyl acrylate, trifluoroethyl acrylate, and tetrahydrofurfuryl acrylate. These may be used alone or in combination of two or more.

[0179] In the acrylic copolymer, the ratio of (a) the structural unit derived from an acrylic ester monomer (structural unit (a)) to (b) the structural unit derived from a monomer such as an unsaturated fatty acid, an acrylamide monomer, a maleimide monomer, vinyl acetate, or a vinyl copolymer (structural unit (b)) is preferably such that the structural unit (a) is 50% by weight to 100% by weight and the structural unit (b) is 0% by weight to 50% by weight.

[0180] The acrylic polymer preferably contains 50% by weight or more of structural units of butyl acrylate (BA), more preferably 60% by weight or more, further preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more.

[0181] The vinyl copolymer is obtained by copolymerizing a mixture of one or more vinyl monomers selected from aromatic vinyl monomers, cyanide vinyl monomers and unsaturated carboxylic acid alkyl ester monomers. The mixture of vinyl monomers may further contain other monomers (hereinafter also referred to as monomer C) copolymerizable with the above monomers.

[0182] As the above-mentioned aromatic vinyl monomer, for example, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, tert-butylstyrene, vinyltoluene, etc. can be mentioned. These vinyl monomers can be used alone or in combination of two or more. Among them, from the viewpoint of being able to easily increase the refractive index, aromatic vinyl monomers are preferred, and styrene is more preferred.

[0183] The unsaturated carboxylic acid alkyl ester monomer is not particularly limited. For example, esters of alcohols having 1 to 6 carbon atoms and acrylic acid or methacrylic acid are preferred. The esters of alcohols having 1 to 6 carbon atoms and acrylic acid or methacrylic acid may further have a substituent such as a hydroxyl group or a halogen group.

[0184] Examples of esters of an alcohol having 1 to 6 carbon atoms and acrylic acid or methacrylic acid include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, chloromethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth)acrylate, and 2,3,4,5-tetrahydroxypentyl (meth)acrylate. These may be used alone or in combination of two or more.

[0185] Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, ethacrylonitrile, etc. These may be used alone or in combination of two or more.

[0186] Monomer C is a vinyl monomer other than the above-mentioned aromatic vinyl monomer, unsaturated carboxylic acid alkyl ester monomer, and cyanide vinyl monomer, and is not particularly limited as long as the effect of the present invention is not impaired. As monomer C, specifically, unsaturated fatty acids, acrylamide monomers, maleimide monomers, vinyl acetate, acrylate monomers, etc. can be cited. These can be used alone or in combination of two or more.

[0187] The unsaturated fatty acid may be selected from, for example, itaconic acid, maleic acid, fumaric acid, crotonic acid, acrylic acid, methacrylic acid, and the like.

[0188] The acrylamide monomer may be selected from, for example, acrylamide, methacrylamide, N-methylacrylamide, and the like.

[0189] The maleimide monomer may be selected from, for example, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-hexylmaleimide, N-octylmaleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide.

[0190] The method for producing the vinyl copolymer is not particularly limited, and examples thereof include emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization.

[0191] In the method for producing the vinyl copolymer, a polymerization initiator may be used as needed, and as the polymerization initiator, for example, one or more of peroxides, azo compounds, potassium persulfate, etc. may be appropriately selected. The amount of the polymerization initiator added is not particularly limited.

[0192] Examples of the peroxide include benzoyl peroxide, cumene hydroperoxide, dicumene peroxide, dicumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl isopropyl carbonate, di-tert-butyl peroxide, tert-butyl peroxyoctanoate, 1,1-bis(tert-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, and tert-butyl peroxy-2-ethylhexanoate. Among these, cumene hydroperoxide, 1,1-bis(tert-butylperoxy)3,3,5-trimethylcyclohexane, and 1,1-bis(tert-butylperoxy)cyclohexane are particularly preferably used.

[0193] Examples of the azo compound include azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile), 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2-cyano-2-propylazocarbonamide, 1,1'-azobiscyclohexane-1-carbonitrile, azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobisisobutyric acid dimethyl ester, 1-tert-butylazo-2-cyanobutane, and 2-tert-butylazo-2-cyano-4-methoxy-4-methylpentane. Among them, 1,1'-azobiscyclohexane-1-carbonitrile is particularly preferably used.

[0194] Specific examples of vinyl copolymers include polyvinyl chloride, chlorinated polyvinyl chloride, polystyrene, styrene-acrylonitrile copolymers, styrene-acrylonitrile-N-phenylmaleimide copolymers, α-methylstyrene-acrylonitrile copolymers, polymethyl methacrylate, methyl methacrylate-styrene copolymers, etc. These may be used alone or in combination of two or more.

[0195] Examples of the polyester include polyethylene terephthalate and polybutylene terephthalate.

[0196] The resin (B) may be the same resin (resin having the same composition) as the component (E) (free radical polymerizable oligomer resin or inert resin) described later, or may be a resin different from the component (E). In the printing ink composition, the component (E) and the resin (B) preferably do not phase separate. The resin (B) is preferably a resin compatible with the component (E).

[0197] When the resin (B) is the same resin as the component (E) described below, there is an advantage that the resin (B) does not affect various physical properties of the printing ink composition containing the obtained powder or particulate matter or the cured film.

[0198] As an example, consider the case where resin (B) is the same type of resin as component (E). In this case, in the printing ink composition, component (E) cannot be distinguished from resin (B). Therefore, in appearance, the printing ink composition can be regarded as (a) having component (E) but not having resin (B), or (b) having resin (B) but not having component (E). Next, consider the case where resin (B) is a different type of resin from component (E). In this case, in the printing ink composition, component (E) and resin (B) can be identified. In this case, the printing ink composition contains component (E), and may contain resin (B) as a resin other than component (E).

[0199] (2-2-3. Others)

[0200] In this specification, resin (B) also includes oils and fatty acid esters. Resin (B) preferably includes oils and fats, and more preferably consists of oils and fats. Examples of oils and fats that can be suitably used as resin (B) include epoxidized oils and fats such as epoxidized soybean oil and epoxidized linseed oil. These resins can be used alone or in combination of two or more. Resin (B) preferably includes epoxidized soybean oil, and more preferably consists of epoxidized soybean oil. As epoxidized soybean oil, commercially available products can also be used, for example, ADK Cizer O-130P manufactured by ADEKA. Examples of fatty acid esters that can be suitably used as resin (B) include epoxidized fatty acid butyl ester, epoxidized fatty acid 2-ethylhexyl ester, epoxidized fatty acid octyl ester, epoxidized fatty acid alkyl ester, and the like.

[0201] Epoxidized fats and oils and epoxidized fatty acid esters are sometimes also referred to as epoxy plasticizers. That is, in this specification, epoxy plasticizers are also included in resin (B). Examples of epoxy plasticizers other than epoxidized fats and oils and epoxidized fatty acid esters include diepoxystearyl epoxyhexahydrophthalate and di-2-ethylhexyl epoxyhexahydrophthalate.

[0202] The above-mentioned thermosetting resins, thermoplastic resins, mixtures of thermosetting resins and thermoplastic resins, oils and fats, and fatty acid esters can be mixed with antioxidants respectively. In this specification, antioxidants are considered as part of resin (B) only when they are mixed with the above-mentioned substances. When only antioxidants are used, antioxidants are not considered as resin (B). The case where only antioxidants are used instead of resin (B) is explained. Since antioxidants are components that do not contribute to crosslinking, the physical properties of the cured film formed by curing the printing ink composition tend to deteriorate. For example, consider the case where the Tg of the cured film is reduced or the impact resistance is deteriorated.

[0203] The antioxidant is not particularly limited and includes, for example, (a) primary antioxidants such as phenolic antioxidants, amine antioxidants, lactone antioxidants, and hydroxylamine antioxidants, and (b) secondary antioxidants such as sulfur antioxidants and phosphorus antioxidants.

[0204] As the above-mentioned phenolic antioxidant, hindered phenolic antioxidants can be mentioned. As hindered phenolic antioxidants, compounds having a hindered phenol structure or a semi-hindered phenol structure in the molecule can be mentioned. As the phenolic antioxidant, commercially available products can also be used, for example, Irganox 245 manufactured by BASF JAPAN Co., Ltd. can be mentioned.

[0205] The amine antioxidant is not particularly limited, and conventionally known substances can be widely used. Specific examples of the amine antioxidant include amine-ketone compounds, 2,2,4-trimethyl-1,2-dihydroquinoline polymers, 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, and a reaction product of diphenylamine and acetone.

[0206] The above-mentioned amine antioxidants also include aromatic amine compounds. Examples of the aromatic amine compounds include naphthylamine antioxidants, diphenylamine antioxidants, and p-phenylenediamine antioxidants.

[0207] The lactone antioxidant, the hydroxylamine antioxidant, and the sulfur antioxidant are not particularly limited, and conventionally known antioxidants can be widely used.

[0208] The phosphorus antioxidant is not particularly limited, and conventionally known substances can be widely used. Phosphoric acid and phosphoric acid esters containing active hydrogen have adverse effects on the storage stability of the printing ink composition and the heat resistance of the cured film provided by the printing ink composition. Therefore, as the phosphorus antioxidant, alkyl phosphites, aryl phosphites, alkyl aryl phosphites, etc. that do not contain phosphoric acid and phosphoric acid esters in the molecule are preferred.

[0209] As the above-mentioned antioxidant, other substances known in the past can also be used. As the antioxidant, for example, various substances recorded in the "Antioxidant Handbook" (first edition issued on October 25, 1975) issued by Dacheng Co., Ltd., the "Polymer Additive Handbook" (written by Haruna Tetsu, first edition issued on November 7, 2010) issued by CMC Publishing, etc. can be used.

[0210] The resin (B) is preferably selected from thermosetting resins, mixtures of thermosetting resins and antioxidants, thermoplastic resins, mixtures of thermoplastic resins and antioxidants, oils, mixtures of oils and antioxidants, fatty acid esters, mixtures of fatty acid esters and antioxidants, epoxy curing agents, and mixtures of epoxy curing agents and antioxidants. It is more preferably selected from epoxy resins, acrylic polymers, mixtures of epoxy resins and antioxidants, mixtures of acrylic polymers and antioxidants, and mixtures of epoxy plasticizers and antioxidants. It is further preferably selected from mixtures of epoxy resins and antioxidants, mixtures of acrylic polymers and antioxidants, and mixtures of epoxy plasticizers and antioxidants. It is particularly preferably a mixture of epoxy plasticizers and antioxidants. According to this configuration, there are advantages that the printing ink composition (a) can provide a cured film having excellent heat resistance and the dispersibility of the polymer particles (A) in the printing ink composition can be improved.

[0211] (2-2-4. Physical properties of resin (B))

[0212] The resin (B) is not particularly limited in other properties as long as it is a liquid, semisolid or solid having a viscosity of 100 to 1,000,000 mPa·s at 25° C. It should be noted that “the resin (B) has a viscosity of 100 to 1,000,000 mPa·s at 25° C.” means that “the resin (B) at 25° C. has a viscosity of 100 to 1,000,000 mPa·s”.

[0213] When the resin (B) is a liquid, the viscosity of the resin (B) at 25° C. is preferably 750,000 mPa·s or less, more preferably 700,000 mPa·s or less, more preferably 500,000 mPa·s or less, more preferably 350,000 mPa·s or less, more preferably 300,000 mPa·s or less, more preferably 250,000 mPa·s or less, more preferably 100,000 mPa·s or less, more preferably 75,000 mPa·s or less, more preferably 50,000 mPa·s or less, more preferably 30,000 mPa·s or less, more preferably 25,000 mPa·s or less, further preferably 20,000 mPa·s or less, and particularly preferably 15,000 mPa·s or less. According to the above configuration, the resin (B) has an advantage of excellent fluidity.

[0214] In addition, the viscosity of the resin (B) is more preferably 100 mPa·s or more, more preferably 200 mPa·s or more, more preferably 300 mPa·s or more, more preferably 400 mPa·s or more, more preferably 500 mPa·s or more, further preferably 750 mPa·s or more, further preferably 1000 mPa·s or more, and particularly preferably 1500 mPa·s or more at 25°C. According to this configuration, the resin (B) does not penetrate into the polymer microparticles (B). Therefore, the resin (B) can prevent the polymer microparticles (B) from fusing with each other.

[0215] The viscosity of resin (B) at 25°C is more preferably 100 mPa·s to 750,000 mPa·s, more preferably 100 mPa·s to 700,000 mPa·s, more preferably 100 mPa·s to 350,000 mPa·s, more preferably 100 mPa·s to 300,000 mPa·s, more preferably 100 mPa·s to 50,000 mPa·s, further preferably 100 mPa·s to 30,000 mPa·s, and particularly preferably 100 mPa·s to 15,000 mPa·s.

[0216] When the resin (B) is semi-solid at 25°C, it can be said that the resin (B) is semi-liquid at 25°C, or it can be said that the resin (B) has a viscosity greater than 1,000,000 mPa·s at 25°C. When the resin (B) is semi-solid or solid at 25°C, the resulting composition has the advantages of low viscosity and easy handling.

[0217] The viscosity of the resin (B) can be measured using a viscometer. The method for measuring the viscosity of the resin (B) is described in detail in the following examples.

[0218] The resin (B) preferably has an endothermic peak at 25° C. or lower in a thermogram of differential scanning calorimetry (DSC), and more preferably has an endothermic peak at 0° C. or lower.

[0219] (2-3. Radically polymerizable oligomer resin and / or inert resin (E))

[0220] In one embodiment of the present invention, the printing ink composition preferably contains a radically polymerizable oligomer resin and / or an inert resin (E). According to this configuration, there are advantages that the viscosity and fluidity of the printing ink composition, and the chemical properties such as film strength and adhesion of the cured film, and the printing ink composition and the cured film are excellent in printability. In this specification, "radical polymerizable oligomer resin and / or inert resin (E)" is sometimes referred to as "component (E)".

[0221] In this specification, the radical polymerizable oligomer resin in the component (E) refers to a resin that can be polymerized by radicals and has a molecular weight of 10,000 or less. As the radical polymerizable oligomer, an oligomer resin is used in which a photo-crosslinkable group such as a (meth)acryloyl group and a photopolymerizable group are introduced into a linear polymer by reacting a (meth)acrylic compound having a reactive substituent with a linear polymer having a reactive substituent. It should be noted that as the reactive substituent in the linear polymer having a reactive substituent, functional groups such as a hydroxyl group, a carboxyl group, and an amino group, and a structure derived from an acid anhydride, etc. can be cited, and as the reactive substituent in the (meth)acrylic compound having a reactive substituent, a hydroxyl group, an isocyanate group, an aldehyde group, an epoxy group, etc. can be cited. For example, as the radical polymerizable oligomer resin, there can be mentioned a half-esterified compound obtained by reacting (b) a (meth)acrylic compound having a hydroxyl group such as (meth) alkyl ester with (a) a linear polymer having a structure derived from an acid anhydride such as a styrene-maleic anhydride copolymer and an α-olefin-maleic anhydride copolymer. The radical polymerizable oligomer resin is not particularly limited, but from the viewpoint of (a) the physical and chemical properties of the cured film (ink film) and (b) the printability of the printing ink composition itself (ease of coating or spraying, viscosity, etc.), it is preferably composed of one or more selected from alkyd acrylates, urethane-modified acrylates, polyester acrylates, and epoxy acrylates, and more preferably only composed of one or more selected from them.

[0222] In the present specification, the inert resin in the component (E) refers to a solid resin which itself is non-reactive. The inert resin is not particularly limited, but from the viewpoints of (a) the physical and chemical properties of the cured film (ink film) and (b) the printability of the printing ink composition itself (ease of coating, viscosity, etc.), for example, preferably (i) contains one or more selected from diallyl phthalate resin, acrylic resin, polyurethane resin, epoxy resin, phenolic resin, cellulose ester resin and polyester resin, more preferably only contains one or more selected therefrom, more preferably (ii) contains at least one of diallyl phthalate resin and acrylic resin, and further preferably only contains at least one of diallyl phthalate resin and acrylic resin.

[0223] The total content of the radical polymerizable oligomer resin and the inert resin in the printing ink composition is preferably 0.5 to 50.0% by weight, more preferably 1.0 to 30.0% by weight, further preferably 1.0 to 20.0% by weight, and particularly preferably 1.0 to 10.0% by weight, relative to 100% by weight of the printing ink composition. This configuration has the advantages of (a) excellent physical and chemical properties of the cured film (ink film) and (b) excellent printability (ease of application, viscosity, etc.) of the printing ink composition itself.

[0224] (2-4. Low molecular weight compounds (C))

[0225] In one embodiment of the present invention, the printing ink composition preferably contains a low molecular weight compound (C). In this specification, the "low molecular weight compound (C)" may be referred to as "component (C)".

[0226] In one embodiment of the present invention, the low molecular compound (C) has at least one polymerizable unsaturated bond in the molecule. Due to this structure, the low molecular compound (C) itself can also be cured when the printing ink composition is cured. In addition, when a free radical polymerizable oligomer resin is included as the (E) component, when the printing ink composition is cured, a curing reaction can occur between the (C) component and the (E) component's free radical polymerizable oligomer resin. Therefore, the low molecular compound (C) can also act as a polymerizable monomer of a cross-linked cured film.

[0227] The low molecular weight compound (C) preferably has at least one polymerizable unsaturated bond in the molecule, more preferably has two polymerizable unsaturated bonds in the molecule, further preferably has three polymerizable unsaturated bonds in the molecule, and particularly preferably has six polymerizable unsaturated bonds in the molecule. This configuration has the advantage of increasing the curing speed.

[0228] In one embodiment of the present invention, the molecular weight of the low molecular compound (C) is less than 1000. Due to this structure, the low molecular compound (C) can function as a reactive diluent in the printing ink composition. For example, the low molecular compound (C) can function as a diluent (solvent) for adjusting the printing ink composition to an appropriate viscosity (lowering it to an appropriate viscosity). That is, by making the printing ink composition contain the low molecular compound (C), the printing ink composition has the advantage of excellent handling properties.

[0229] The molecular weight of the low molecular weight compound (C) is preferably less than 1000, more preferably less than 900, further preferably less than 800, and particularly preferably less than 700. This configuration has the advantage that the viscosity of the printing ink composition can be easily adjusted.

[0230] In the application requiring the hardness of the curing speed and the cured film, as a reactive diluent, it is preferred to use a low molecular compound (C) having at least three or more polymerizable unsaturated bonds in one molecule. However, in the past, if a large amount of low molecular compound (C) having at least three or more polymerizable unsaturated bonds in one molecule was used (for example, in 100% by weight of the printing ink composition, more than 10% by weight), the shrinkage of the cured film becomes significant as the printing ink composition is cured, and there is a trend that the adhesion of the cured film is deteriorated due to the residual stress generated in the cured film. However, the present printing ink composition, by comprising the above-mentioned polymer particles (A), can reduce the residual stress in the cured film even in the case of comprising a large amount of low molecular compound (C) having at least three or more polymerizable unsaturated bonds in one molecule. Therefore, the present printing ink composition has the advantages of excellent curing speed and hardness of the cured film and excellent adhesion to the substrate.

[0231] In one embodiment of the present invention, the low molecular weight compound (C) preferably contains 5% by weight or more of a low molecular weight compound having at least three or more polymerizable unsaturated bonds in one molecule in 100% by weight of the low molecular weight compound (C), more preferably 10% by weight or more, further preferably 15% by weight or more, and particularly preferably 20% by weight or more. According to this constitution, there is an advantage of faster curing speed.

[0232] Specific examples of the low molecular weight compound (C) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, ethoxylated 1,6-hexanediol diacrylate, neopentyl glycol di(meth)acrylate, polypropylene glycol diacrylate, 1,4-butanediol di(meth)acrylate, 1,9-nonanediol diacrylate, tetraethylene glycol diacrylate, 2-n-butyl-2-ethyl-1,3-propanediol diacrylate, dimethylol tricyclodecane diacrylate, hydroxy neopentyl glycol diacrylate, 1,3-butanediol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dimethylol dicyclopentane diacrylate, trimethylolpropane triacrylate. Acid ester, hydroxy neopentanoic acid trimethylolpropane triacrylate, ethoxylated phosphoric acid triacrylate, ethoxylated tripropylene glycol diacrylate, neopentyl glycol modified trimethylolpropane diacrylate, stearic acid modified pentaerythritol diacrylate, pentaerythritol triacrylate, tetramethylolpropane triacrylate, tetramethylolmethane triacrylate, pentaerythritol tetraacrylate, caprolactone modified trimethylolpropane triacrylate, ethoxylated isocyanuric acid triacrylate, tris (2-hydroxyethyl isocyanurate) triacrylate, propoxylated glycerol triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, caprolactone modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, neopentyl glycol oligoacrylate, 1,4-butanediol oligoacrylate, 1,6-Hexanediol oligoacrylate, trimethylolpropane oligoacrylate, pentaerythritol oligoacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, tert-butyl acrylate, isooctyl acrylate, cyclohexyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, benzyl acrylate, ethoxyethoxyethyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydipropylene glycol acrylate, methylphenoxyethyl acrylate, dipropylene glycol acrylate, β-carboxyethyl acrylate, ethyldiethylene glycol acrylate, trimethylolpropane formal monoacrylate Acrylate, 4-tert-butylcyclohexyl acrylate, tri(meth)allyl isocyanurate, acrylate imide, isoamyl acrylate, ethoxylated succinic acid acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, tribromophenyl acrylate, ethoxylated tribromophenyl acrylate, trifluoroethyl acrylate, ω-carboxy polycaprolactone monoacrylate, acryloyl morpholine, ethoxylated neopentyl glycol di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, phenoxydiethylene glycol acrylate, vinyl pyrrolidone, N-vinyl formamide, 1,4-cyclohexanedimethanol monoacrylate, etc. Component (C) is not limited to these. These compounds can be used alone or in combination of two or more as needed. The component (C) preferably contains one or more low molecular weight compounds having at least three polymerizable unsaturated bonds in one molecule, or is composed of only one or more low molecular weight compounds selected from these low molecular weight compounds. This configuration has the advantage of faster curing speed.

[0233] It should be noted that the content of the low molecular weight compound (C) is not particularly limited, and is preferably 5% to 90% by weight, more preferably 7% to 80% by weight, more preferably 10% to 70% by weight, more preferably 15% to 60% by weight, further preferably 15% to 50% by weight, and particularly preferably 20% to 40% by weight, relative to 100% by weight of the printing ink composition. The content of the low molecular weight compound (C) may be 30% by weight or more, or 40% by weight or more relative to 100% by weight of the printing ink composition. According to this configuration, there is an advantage that the viscosity of the printing ink composition can be easily adjusted.

[0234] (2-5. Pigment (D))

[0235] In one embodiment of the present invention, the printing ink composition contains a pigment (D). This configuration has the advantage of being able to color the printing ink composition. In this specification, the "pigment (D)" may be referred to as "component (D)".

[0236] The pigment (D) used in one embodiment of the present invention is not particularly limited, and known pigments can be used. For example, the pigments described in "Dictionary of Pigments" (2000 edition) compiled by Seishiro Ito, W. Herbst, K. Hunger "Industrial Organic Pigments", Japanese Patent Publication No. 2002-12607, Japanese Patent Publication No. 2002-188025, Japanese Patent Publication No. 2003-26978, and Japanese Patent Publication No. 2003-342503 can be used.

[0237] The content of the pigment (D) in the present printing ink composition is 1% by weight or more, preferably 2% by weight or more, more preferably 3% by weight or more, and further preferably 5% by weight or more, relative to 100% by weight of the printing ink composition. This configuration has the advantage that the color development of the cured film obtained by curing the printing ink composition is excellent.

[0238] (2-6. Photopolymerization initiator (F))

[0239] In one embodiment of the present invention, the printing ink composition preferably contains a photopolymerization initiator (F). According to this configuration, there is an advantage that the printing ink composition can be cured by irradiation with light. In this specification, the "photopolymerization initiator (F)" is sometimes referred to as the "(F) component".

[0240] The photopolymerization initiator (F) used in one embodiment of the present invention is not particularly limited, and a known photopolymerization initiator can be used. For example, Bruce M. Monroe et al., Chemical Revue, 93, 435 (1993); RS Davidson, Journal of Photochemistry and biology A: Chemistry, 73. 81 (1993); JP Faussier "Photoinitiated Polymerization-Theory and Applications": Rapra Review vol. 9, Report, Rapra Technology (1998); M. Tsunooka et al., Prog. Polym. Sci., 21, 1 (1996); can be used. In addition, the chemically amplified photoresists and compounds used for photocationic polymerization described in the reference "Organic Materials for Imaging" compiled by the Organic Electronic Materials Research Association, extended edition (1993), pages 187 to 192 can be used. In addition, the photopolymerization initiators described in FD Saeva, Topics in Current Chemistry, 156, 59 (1990)., GG Maslak, Topics in Current Chemistry, 168, 1 (1993)., HB Shuster et al., JACS, 112, 6329 (1990). and IDF Eggon et al., JACS, 102, 3298 (1980) can be used. From the viewpoint of curability, the photopolymerization initiator (F) preferably contains one or more selected from alkyl acetophenone polymerization initiators, alkyl phenyl ketone polymerization initiators, benzoin alkyl ether polymerization initiators, benzophenone polymerization initiators, thioxanthone polymerization initiators and anthraquinone polymerization initiators, or consists of only one or more selected from them.

[0241] The content of the photopolymerization initiator (F) in the printing ink composition is preferably 0.1 to 30.0% by weight, more preferably 0.5 to 20.0% by weight, and even more preferably 1.0 to 20.0% by weight relative to 100% by weight of the printing ink composition. This configuration has the advantage of good curability.

[0242] The content of the photopolymerization initiator (F) in the present printing ink composition is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, more preferably 1.0% by weight or more, more preferably 1.5% by weight or more, further preferably 2.0% by weight or more, and particularly preferably 2.5% by weight or more, relative to 100% by weight of the printing ink composition. This configuration has the advantage that both the curability and adhesion of the curable composition are excellent.

[0243] The content of the low molecular weight compound (C) having at least three polymerizable unsaturated bonds in one molecule of the printing ink composition is preferably 2% by weight or more, more preferably 5% by weight or more, further preferably 7.5% by weight or more, and particularly preferably 10% by weight or more relative to 100% by weight of the printing ink composition. This configuration has the advantage that both the curability and adhesion of the curable composition are excellent.

[0244] (2-7. Additives)

[0245] The printing ink composition may contain other optional components in addition to the above components as required. Examples of other optional components include photopolymerization inhibitors, waxes, leveling agents, photoinitiator aids, sensitizers, active energy ray curing catalysts, fillers, matting agents, defoaming agents, dispersants, surface conditioners, antistatic agents, antioxidants, conductive agents, silicon, flame retardants, plasticizers, thermal conductivity improvers, silane coupling agents, and the like.

[0246] It should be noted that as components other than the polymer particles (A) and the resin (B), commercial products can be used. As the commercial products, offset UV ink (FD LPC PR I CM manufactured by Toyo Ink Co., Ltd.) and inkjet UV ink (LH-100 manufactured by Mimaki Engineering Co., Ltd.) are preferred. According to this structure, there is an advantage of obtaining a good printed product.

[0247] (2-8. Method for producing printing ink composition)

[0248] The printing ink composition can be produced by mixing the above-mentioned components. For example, a method for producing a printing ink composition by mixing (a) a powder containing polymer microparticles (A) and an optional resin (B) with components other than the polymer microparticles (A) and the resin (B) (or commercial products containing the components) (Method 1); or a method for producing a printing ink composition by mixing (b) a dispersion (also called a masterbatch) in which polymer microparticles (A) are dispersed in component (C) and a resin, etc. with components other than these (and an optional additional component (C)) (or commercial products containing the components) (Method 2).

[0249] A method for producing a UV curable printing ink composition according to one embodiment of the present invention may have the following configuration:

[0250] a step of preparing a powder containing polymer microparticles (A); and

[0251] A step of mixing the powder and the pigment (D) to prepare a UV curable printing ink composition;

[0252] The polymer fine particles (A) include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer.

[0253] The elastomer comprises at least one selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber,

[0254] The grafted portion includes a polymer having a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth)acrylate monomer.

[0255] The content of the pigment (D) in the UV curable printing ink composition is 1% by weight or more based on 100% by weight of the UV curable printing ink composition.

[0256] In addition, a method for producing a UV curable printing ink composition according to another embodiment of the present invention may also be configured as follows:

[0257] a step of preparing a dispersion containing polymer microparticles (A), and

[0258] A step of mixing the dispersion with a pigment (D) to prepare a UV curable printing ink composition;

[0259] The polymer fine particles (A) include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer.

[0260] The elastomer is selected from one or more of diene rubber, (meth)acrylate rubber and organosiloxane rubber.

[0261] The grafted portion includes a polymer having a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth)acrylate monomer.

[0262] The content of the pigment (D) in the UV curable printing ink composition is 1% by weight or more based on 100% by weight of the UV curable printing ink composition.

[0263] The present printing ink composition can be produced by either method 1 or method 2. Method 1 is preferred because there is no limitation on the formulation.

[0264] In the case of adopting method 1, the UV-curable printing ink composition involved in one embodiment of the present invention can be the following: the UV-curable printing ink composition is obtained by dispersing powder and particles of polymer microparticles (A) in the printing ink composition, and contains a pigment (D), the above-mentioned polymer microparticles (A) contain a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer, the above-mentioned elastomer contains one or more selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber, the above-mentioned graft portion contains a polymer, and the polymer contains a structural unit derived from one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylate monomers, and the content of the above-mentioned pigment (D) in the above-mentioned UV-curable printing ink composition is 1 weight% or more relative to 100 weight% of the UV-curable printing ink composition.

[0265] (2-8-1. Method 1)

[0266] (Powder and Particle)

[0267] In this specification, "powder and granule" includes both powder and granule, and refers to an aggregate of powder, granule, etc. In addition, when a special distinction is made, "powder" refers to a substance with a volume average particle size of 0.01mm to 0.1mm, and "granule" refers to a substance with a volume average particle size of 0.1mm to 10mm. However, powder and granule may contain powder and granule of 10mm or more as coarse particles. In addition, the "volume average particle size" in the range of less than 10μm can be measured using a dynamic light scattering (DLS) particle size distribution measuring device Nanotrac WaveII-EX150 (manufactured by Micro Track Bell Co., Ltd.), and the "volume average particle size" in the range of more than 10μm is measured using a laser diffraction particle size distribution measuring device Micro TrackMT3000II (manufactured by Micro TrackBell Co., Ltd.).

[0268] (Method for producing powder and granular material)

[0269] The method for producing a powder or granule according to one embodiment of the present invention, in other words, the process for producing a powder or granule containing polymer particles (A) includes: a coagulation step for producing an agglomerate containing polymer particles (A), and a drying step for air flow drying or freeze drying the agglomerate. The polymer particles (A) include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer. The elastomer preferably includes one or more selected from diene rubber, (meth)acrylate rubber and organosilicone rubber. The graft portion preferably includes a polymer, which includes a structural unit derived from one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers and (meth)acrylate monomers as a structural unit. Sometimes the "method for producing a powder or granule according to one embodiment of the present invention" is referred to as the "present production method".

[0270] Since the present production method has the above-mentioned structure, it has the advantage of being able to provide a powder or granule having excellent dispersibility in a printing ink composition of the polymer microparticles (A). In other words, since the present production method has the above-mentioned structure, it has the advantage of being able to provide a powder or granule that can provide a printing ink composition in which the polymer microparticles (A) are uniformly dispersed.

[0271] Hereinafter, each step of the present production method will be described in detail, and matters other than those described below (such as various components and their addition amounts, etc.) are not particularly limited. It should be noted that, as described above, the powder or granule preferably further contains a resin (B). Hereinafter, an example is given to describe in detail the production method of a powder or granule containing a resin (B).

[0272] (Coagulation process)

[0273] The aggregation step is not particularly limited as long as aggregates finally containing the polymer fine particles (A) and the resin (B) can be obtained, in other words, the finally obtained aggregates contain the polymer fine particles (A) and the resin (B).

[0274] The coagulation step may include, for example, the following steps in order: a preparation step (a1) of preparing an aqueous latex containing polymer particles (A) and a resin (B); and a coagulation step (a2) of coagulating the polymer particles (A) and the resin (B) in the obtained aqueous latex.

[0275] The preparation step (a1) is not particularly limited as long as an aqueous latex containing polymer particles (A) and resin (B) can be obtained. Examples of methods for obtaining an aqueous latex containing polymer particles (A) and resin (B) include (i) a method of adding resin (B) to a reaction solution during a polymerization step of polymer particles (A); (ii) a method of adding resin (B) to an aqueous latex of polymer particles (A); and (iii) a method of polymerizing resin (B) in an aqueous latex of polymer particles (A).

[0276] The method of adding the resin (B) to the reaction solution in the polymerization step of the polymer particles (A) or the aqueous latex of the polymer particles (A) is not particularly limited. For example, there can be mentioned: (i) a method of directly adding the resin (B) to the above-mentioned reaction solution or the above-mentioned aqueous latex, (ii) a method of separately preparing an aqueous latex containing the resin (B) and then adding the aqueous latex containing the resin (B), and (iii) a method of separately preparing a solution containing the resin (B) and then adding the solution containing the resin (B). As a method for adding the resin (B), a method of separately preparing an aqueous latex containing the resin (B) and then adding the aqueous latex containing the resin (B) to the above-mentioned reaction solution or the above-mentioned aqueous latex is preferred.

[0277] In the aggregation step (a2), when a coagulant is used, the resin (B) may be added to the aqueous latex of the polymer particles (A) before or after the coagulant is added. Alternatively, the coagulant and the resin (B) may be added to the polymer particles (A) together.

[0278] As a method for obtaining an aqueous latex containing polymer fine particles (A) and a resin (B), a method of adding the resin (B) in an aqueous latex state to an aqueous latex of polymer fine particles (A) is preferred.

[0279] The coagulation step (a2) is not particularly limited as long as coagulations containing polymer particles (A) and resin (B) can be obtained. The method for coagulating the polymer particles (A) and the resin (B) in the aqueous latex together is not particularly limited. As the method, for example, known methods such as a method using a coagulant, a method using a solvent, and a method of spraying aqueous latex can be cited. Here, a mixture containing coagulations containing polymer particles (A) and resin (B) and an aqueous solvent is referred to as a slurry, and the coagulations are obtained by coagulating the polymer particles (A) and the resin (B) in the aqueous latex together.

[0280] In order to improve the anti-blocking property and to improve the dispersibility of the polymer fine particles (A) in the printing ink composition, the aggregation of the polymer fine particles (A) and the resin (B) in the aqueous latex is preferably performed in the presence of an anti-blocking agent.

[0281] The aggregation step (a2) preferably employs a method using a coagulant. In other words, it is preferred to use a coagulant in the aggregation step in the present production method.

[0282] The coagulant is not particularly limited as long as it is a substance having the property of aggregating (also referred to as coagulation and solidification) the polymer microparticles (A) and the resin (B) in the aqueous latex by contacting the aqueous latex containing the polymer microparticles (A) and the resin (B). Examples of the coagulant include aqueous solutions of inorganic salts, aqueous solutions of inorganic acids, aqueous solutions of organic salts, aqueous solutions of organic acids, and polymer coagulants.

[0283] Examples of the inorganic salt include chloride salts, bromide salts, iodide salts, sulfates, nitrates, ammonium salts, phosphates, etc. Specific examples of the inorganic salt include sodium chloride, potassium chloride, lithium chloride, sodium bromide, potassium bromide, lithium bromide, potassium iodide, sodium iodide, potassium sulfate, sodium sulfate, ammonium sulfate, ammonium chloride, sodium nitrate, potassium nitrate, calcium chloride, ferrous sulfate, magnesium sulfate, zinc sulfate, copper sulfate, barium chloride, ferrous chloride, ferric chloride, magnesium chloride, ferric sulfate, aluminum sulfate, potassium alum, iron alum, etc.

[0284] Examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and the like.

[0285] Examples of the organic salt include alkali metal or alkaline earth metal acetates, citrates, formates, gluconates, lactates, oxalates, tartrates, etc. Specific examples of the organic acid salt include sodium acetate, calcium acetate, sodium formate, calcium formate, etc.

[0286] Examples of the organic acid include acetic acid and formic acid.

[0287] As a polymer coagulant, as long as it is a polymer compound having a hydrophilic group and a hydrophobic group, it is not particularly limited, and it can also be any polymer coagulant of anionic, cationic, and nonionic systems. From the aspect of being able to further improve the effect of one embodiment of the present invention, as a polymer coagulant, a cationic polymer coagulant is preferred. As a cationic polymer coagulant, as long as it is a polymer coagulant having a cationic group in the molecule, that is, a polymer coagulant that shows cationicity when dissolved in water. As a cationic polymer coagulant, for example, polyamines, polydicyandiamides, cationized starch, cationic poly (methyl) acrylamide, water-soluble aniline resins, polythioureas, polyethyleneimines, quaternary ammonium salts, polyvinyl pyridines, chitosan, etc. can be cited.

[0288] As a coagulant, among the above compounds, only one may be used, or two or more may be used in combination. As a coagulant, among the above compounds, sodium chloride, potassium chloride, sodium sulfate, ammonium chloride, calcium chloride, magnesium chloride, magnesium sulfate, barium chloride, hydrochloric acid, sulfuric acid, etc., monovalent or divalent inorganic salts or aqueous solutions of inorganic acids may be appropriately used. There is no particular limitation on the method for adding the above coagulant, and the coagulant may be added all at once, in portions, or continuously.

[0289] By bringing an aqueous latex containing polymer particles (A) and a resin (B) into contact with a coagulant or a solution of a coagulant (e.g., an aqueous solution), the polymer particles (A) and the resin (B) can be coagulated. The method for bringing an aqueous latex containing polymer particles (A) and a resin (B) into contact with a coagulant or a solution of a coagulant is not particularly limited. Examples of the method include (i) a method of bringing an aqueous latex containing polymer particles (A) and a resin (B) into contact with a coagulant or a solution of a coagulant (hereinafter referred to as coagulation method 1), and (ii) a method of bringing droplets containing polymer particles (A) and a resin (B) obtained by spraying an aqueous latex containing polymer particles (A) and a resin (B) into contact with a coagulant or a solution of a coagulant (hereinafter referred to as coagulation method 2).

[0290] Aggregation method 1 is a method using an aqueous latex containing polymer particles (A) and a resin (B) as a liquid phase, in other words, a method without spraying an aqueous latex containing polymer particles (A) and a resin (B). In this specification, aggregation method 1 is also referred to as "liquid phase coagulation".

[0291] The coagulation method 1 is described in detail. Specific examples of the coagulation method 1 include (1-i) a method of adding a coagulant to an aqueous latex containing polymer particles (A) and a resin (B), (1-ii) a method of mixing an aqueous latex containing polymer particles (A) and a resin (B) with a solution of a coagulant, and (1-iii) a method of spraying a coagulant or a solution of a coagulant onto an aqueous latex containing polymer particles (A) and a resin (B). The method (1-iii) described above can also be said to be a method of spraying a coagulant or a solution of a coagulant in the presence of polymer particles (A) and a resin (B). In the coagulation method 1, an aqueous latex containing polymer particles (A), a resin (B) and a coagulant can be obtained.

[0292] The coagulation method 1 may further include a step of heating the obtained aqueous latex (the aqueous latex containing polymer particles (A), resin (B) and coagulant). In the case of the step of heating the aqueous latex containing polymer particles (A), resin (B) and coagulant, there is an advantage that the water content of the obtained coagulation can be reduced, and / or the fine powder in the obtained powder can be reduced. In the heating step, the temperature (heating temperature) of the aqueous latex obtained by heating the aqueous latex containing polymer particles (A), resin (B) and coagulant is not particularly limited.

[0293] Agglomeration method 2 is a method of spraying an aqueous latex containing polymer particles (A) and a resin (B), in other words, a method of using an aqueous latex containing polymer particles (A) and a resin (B) as droplets. In this specification, aggregation method 2 is also referred to as "gas phase coagulation".

[0294] The coagulation method 2 is described in detail. Specific examples of the coagulation method 2 include (2-i) a method of spraying an aqueous latex containing polymer particles (A) and a resin (B) into a coagulant or a solution of a coagulant, (2-ii) a method of spraying an aqueous latex containing polymer particles (A) and a resin (B) and spraying a coagulant or a solution of a coagulant, etc. The method (2-i) described above can also be said to be a method including a polymer particle spraying step of spraying an aqueous latex containing polymer particles (A) and a resin (B) in the presence of a coagulant.

[0295] The method of (2-ii) described above is described in detail. The method of (2-ii) described above may include the following methods: (2-ii-a) a method of contacting droplets containing polymer particles (A) and / or resin (B) obtained by spraying with droplets containing a coagulant obtained by spraying; (2-ii-b) a method of spraying an aqueous latex containing polymer particles (A) and resin (B) to an area (space) where droplets containing a coagulant obtained by spraying exist; and (2-ii-c) a method of spraying a solution of a coagulant to an area (space) where droplets containing polymer particles (A) and / or resin (B) obtained by spraying exist. Here, the area (space) where droplets containing a coagulant exist can also be said to be in the presence of a coagulant. In addition, the area (space) where droplets containing polymer particles (A) and / or resin (B) exist can also be said to be in the presence of polymer particles (A) and resin (B). Therefore, the above method (2-ii) can also be said to be a method comprising a polymer particle spraying step of spraying an aqueous latex containing polymer particles (A) and a resin (B) in the presence of a coagulant, and a coagulant spraying step of spraying a coagulant or a solution containing a coagulant in the presence of polymer particles (A) and a resin (B).

[0296] The coagulation step in the present manufacturing method is preferably carried out by coagulation method 2, i.e., "gas phase coagulation". In other words, the coagulation step in the present manufacturing method preferably further includes a polymer particle spraying step of spraying an aqueous latex containing polymer particles (A) and a resin (B) in the presence of a coagulant. According to this structure, there is an advantage that a powder or granule having a smaller proportion of particles with a volume average particle size of 1000 μm or more or particles with a volume average particle size of 600 μm or more relative to the total amount of the powder or granule can be obtained. In the coagulation step in the present manufacturing method, in addition to the polymer particle spraying step, it is more preferably further included a coagulant spraying step of spraying a solution containing a coagulant or a coagulant in the presence of polymer particles (A) and a resin (B). According to this structure, there is an advantage that a powder or granule having a smaller proportion of particles with a volume average particle size of 1000 μm or more or particles with a volume average particle size of 600 μm or more relative to the total amount of the powder or granule can be obtained.

[0297] Through the above-mentioned preparation step (a1) and aggregation step (a2), a slurry containing aggregates of polymer microparticles (A) and resin (B) can be obtained. The aggregation step may further include a recovery step (a3) ​​of recovering the aggregates obtained from the slurry, that is, the aggregates containing polymer microparticles (A) and resin (B).

[0298] The recovery step (a3) ​​is not particularly limited as long as the aqueous solvent of the slurry and the aggregates can be separated, and a known method can be used. Examples of the recovery step (a3) ​​include a method of filtering the slurry and a method of centrifugally dehydrating the slurry.

[0299] As other methods of the coagulation step, for example, there can be cited a method which includes the following steps in sequence: a coagulation step (b1) of using an aqueous latex containing only polymer particles (A) to coagulate the polymer particles (A) in the aqueous latex; a recovery step (b2) of recovering the obtained coagulates of the polymer particles (A); and a mixing step (b3) of mixing the recovered coagulates of the polymer particles (A) with the resin (B).

[0300] In the aggregation step (b1), the same method as the above-mentioned aggregation step (a2) may be used, including a preferred embodiment, except that an aqueous latex containing only the polymer fine particles (A) is used instead of an aqueous latex containing the polymer fine particles (A) and the resin (B).

[0301] In the recovery step (b2), the recovery step (b2) may be performed in the same manner as in the above recovery step (a3), including a preferred embodiment, except that the aggregates contain only the polymer fine particles (A) instead of the polymer fine particles (A) and the resin (B).

[0302] In the mixing step (b3), the method for mixing the recovered polymer microparticles (A) and the resin (B) is not particularly limited and examples of the method include mechanical mixing methods using a rotation-revolution mixer, a planetary mixer, a disperser, and the like.

[0303] (Water content of aggregate)

[0304] The aggregates containing polymer particles (A) and resin (B) obtained in the aggregation step may contain water. The water content of the aggregates is preferably 10% to 70% relative to the total weight (100% by weight) of the aggregates, more preferably 20% to 60%, more preferably 30% to 60%, further preferably 30% to 50%, and particularly preferably 30% to 40%. The water content of the aggregates can be measured by drying the obtained aggregates in an oven at 120° C. for 1 hour and comparing the weights before and after drying.

[0305] (Drying process)

[0306] The drying step is a step of drying the aggregates containing the polymer microparticles (A) and the resin (B) obtained in the above-mentioned aggregation step. In the present production method, the aggregates are subjected to airflow drying or freeze drying in the drying step.

[0307] In this specification, airflow drying refers to drying the aggregate while flying in a certain space. There is no particular limitation on the airflow drying method, and a conventionally known method can be used. As an example of airflow drying, a method can be cited in which the aggregate is stored in a container, a gas at a predetermined temperature is introduced into the container, and the aggregate is dried while flying in the container.

[0308] The atmospheric temperature during the drying step is not particularly limited. From the perspective that the obtained powder and granules can provide a printing ink composition having a more excellent dispersibility of the polymer particles (A), the drying step is preferably performed at 100°C or less, more preferably at 90°C or less, more preferably at 80°C or less, more preferably at 70°C or less, more preferably at 60°C or less, more preferably at 50°C or less, more preferably at 40°C or less, more preferably at 30°C or less, more preferably at 20°C or less, further preferably at 10°C or less, and particularly preferably at 0°C or less.

[0309] In air flow drying, the atmospheric temperature during the drying step can be adjusted by changing the temperature in the container containing the aggregates and / or the temperature of the gas fed into the container.

[0310] In the air flow drying, the gas fed into the container is not particularly limited, but examples of the gas include air, nitrogen, a mixture of nitrogen and air, a mixture of nitrogen and oxygen, and a rare gas.

[0311] The freeze-drying method is not particularly limited, and a conventionally known method can be used. When freeze-drying is used as the drying step, the drying step can be easily performed at 0°C or lower.

[0312] The time of the drying process is not particularly limited and can be appropriately set according to the degree of drying of the agglomerate. The drying time can be, for example, 1 minute to 3 hours, preferably 1 minute to 1 hour, more preferably 1 minute to 30 minutes, further preferably 1 minute to 20 minutes, and particularly preferably 1 minute to 10 minutes. The drying process can be carried out, for example, before the temperature of the agglomerate (powder and granular body) reaches 40°C.

[0313] In this specification, a method of drying the aggregates containing polymer fine particles (A) and resin (B) by standing in a container such as an oven as in the related art is also referred to as "standing drying".

[0314] (Washing process)

[0315] The present production method preferably further comprises a step of washing the agglomerates obtained in the agglomeration step between the agglomeration step and the drying step. By washing the agglomerates, a powder with a small content of inclusions etc. can be obtained. In the washing step, it is more preferred to wash the agglomerates with water, and it is further preferred to wash with ion exchange water or pure water.

[0316] The specific method of the washing process is not particularly limited as long as it is a process for washing the agglomerates. As specific methods of the washing process, for example, a method of mixing the agglomerates with water and stirring them with a stirrer, a method of kneading the agglomerates with water using a kneader, a method of mixing the agglomerates with water using a rotation and revolution mixer, a method of spraying water on the agglomerates, a method of washing filter cakes using a pressure filter, etc. can be cited. As kneading machines, various intermittent kneading machines, continuous kneading machines, extrusion kneading machines, extruders, etc. can be used.

[0317] The washing time is not particularly limited, and for example, 1 second to 60 minutes can be cited. The washing time is preferably 1 second to 45 minutes, more preferably 1 second to 30 minutes, more preferably 1 minute to 30 minutes, further preferably 3 minutes to 30 minutes, particularly preferably 5 minutes to 30 minutes, and particularly preferably 10 minutes to 30 minutes.

[0318] The number of washing is not particularly limited, and for example, 1 to 10 times (cycles) may be mentioned. The number of washing is preferably 1 to 6 times (cycles), more preferably 1 to 5 times (cycles), further preferably 1 to 4 times (cycles), and most preferably 1 to 3 times (cycles).

[0319] The amount of washing water is not particularly limited, and for example, 0.1 to 1000 parts by weight can be cited relative to 1 part by weight of the agglomerate. The amount of washing water is preferably 1 to 1000 parts by weight, more preferably 1 to 500 parts by weight, more preferably 1 to 200 parts by weight, more preferably 10 to 200 parts by weight, further preferably 15 to 200 parts by weight, and particularly preferably 20 to 200 parts by weight. The amount of washing water is also preferably 1 to 10 parts by weight, further preferably 2 to 10 parts by weight, and further preferably 2 to 5 parts by weight relative to 1 part by weight of the agglomerate. In addition, in the case of washing by kneading the agglomerate and water using a kneader, it is more preferred because the amount of washing water can be reduced.

[0320] The temperature of the washing water is also not limited, and for example, water at room temperature or heated water can be used appropriately. For the washing effect, warm water has a higher washing effect, so it is preferable to use heated washing water. As the temperature of the washing water, for example, 10°C to 100°C can be cited, but it is preferably 15°C to 100°C, more preferably 20°C to 100°C, more preferably 40°C to 100°C, more preferably 40°C to 90°C, further preferably 40°C to 85°C, further preferably 40°C to 80°C, and particularly preferably 40°C to 70°C.

[0321] In the washing step, the method for removing the water after washing is not limited, and examples thereof include draining the washing water, vacuum filtration, oil-water separation, filter pressing, centrifugal separation, belt pressing, screw pressing, membrane separation, and squeeze dehydration.

[0322] The object to be washed refers to all impurities contained in the aggregates, and is not particularly limited. For example, in addition to impurities derived from emulsifiers (such as phosphorus emulsifiers and sulfonic acid emulsifiers), impurities derived from coagulants when coagulants are used can be mentioned.

[0323] (temperature)

[0324] The agglomerates and powders containing polymer particles (A) and resin (B) are preferably operated (treated) in a temperature environment lower than the glass transition temperature of the grafted portion of the polymer particles (A) in the entire manufacturing method. In other words, in the entire manufacturing method, the agglomerates and powders containing polymer particles (A) and resin (B) are exposed to a temperature environment higher than the glass transition temperature of the grafted portion of the polymer particles (A) for as little time as possible. According to this configuration, the obtained powder can provide a printing ink composition with better dispersibility of the polymer particles (A) (i.e., the polymer particles (A) are more uniformly dispersed).

[0325] In the present production method, the time (period) during which the agglomerates and granules containing polymer particles (A) and resin (B) are exposed to a temperature environment above the glass transition temperature of the grafted portion of the polymer particles (A) can be shortened by adjusting the following temperatures: the temperature of the aqueous latex containing polymer particles (A), the temperature of the aqueous latex containing polymer particles (A) and resin (B) (the aqueous latex before the addition of the coagulant), the temperature of the aqueous solution of the coagulant, the temperature of the aqueous latex containing polymer particles (A), resin (B) and coagulant, the heating temperature in the heating step, the drying temperature in the drying step, the temperature of the washing water in the washing step, etc.

[0326] The temperature lower than the glass transition temperature of the grafted part of the polymer microparticles (A) can vary depending on the composition of the grafted part, and can be appropriately set according to the composition of the grafted part. The agglomerates and granules containing the polymer microparticles (A) and the resin (B) are preferably treated in an environment of less than 90°C, more preferably in an environment of less than 80°C, and further preferably in an environment of less than 70°C in the entire production method. That is, each of the above temperatures is preferably less than 90°C, more preferably less than 80°C, more preferably less than 70°C, more preferably less than 60°C, more preferably less than 50°C, and further preferably less than 40°C.

[0327] The content of the resin (B) in the powder is preferably 50 to 99% by weight and 1 to 50% by weight of the polymer particles (A) and the resin (B), respectively, when the total of the polymer particles (A) and the resin (B) is 100% by weight. The content of the resin (B) in the powder can be appropriately set within the above numerical range according to the type of the resin (B) and the physical properties of the resin (B) (solid, semi-solid, liquid or viscosity, etc.). When the resin (B) is liquid at 25°C and the content of the resin (B) in the powder is high, the powder may not be obtained. When the resin (B) is liquid at 25°C and the content of the resin (B) in the powder is high, the fluidity (smoothness) of the powder may be deteriorated.

[0328] From the perspective of excellent anti-blocking properties, the content of the resin (B) in the powder and granule is described. When the total of the polymer microparticles (A) and the resin (B) is 100% by weight, it is more preferred that the polymer microparticles (A) are 55 to 99% by weight and the resin (B) is 1 to 45% by weight, more preferably the polymer microparticles (A) are 60 to 99% by weight and the resin (B) is 1 to 40% by weight, more preferably the polymer microparticles (A) are 65 to 99% by weight and the resin (B) is 1 to 35% by weight, more preferably the polymer microparticles (A) are 70 to 99% by weight and the resin (B) is 1 to 30% by weight, and more preferably It is preferred that the polymer particles (A) are 75 to 99% by weight and the resin (B) is 1 to 25% by weight, more preferably the polymer particles (A) are 80 to 99% by weight and the resin (B) is 1 to 20% by weight, further preferably the polymer particles (A) are 85 to 99% by weight and the resin (B) is 1 to 15% by weight, further preferably the polymer particles (A) are 90 to 99% by weight and the resin (B) is 1 to 10% by weight, and particularly preferably the polymer particles (A) are 95 to 99% by weight and the resin (B) is 1 to 5% by weight.

[0329] From the perspective of improving the dispersibility of the polymer microparticles (A) in the printing ink composition, the content of the resin (B) in the powder is described. When the total of the polymer microparticles (A) and the resin (B) is 100% by weight, preferably the polymer microparticles (A) are 50 to 97% by weight and the resin (B) are 3 to 50% by weight, more preferably the polymer microparticles (A) are 50 to 95% by weight and the resin (B) are 5 to 50% by weight, more preferably the polymer microparticles (A) are 50 to 92% by weight and the resin (B) are 8 to 50% by weight, more preferably the polymer microparticles (A) are 50 to 90% by weight and the resin (B) are 10 to 50% by weight, and more preferably the polymer microparticles (A) are 50 to 92% by weight and the resin (B) are 8 to 50% by weight. The polymer particles (A) are 50 to 87% by weight and the resin (B) is 13 to 50% by weight, more preferably the polymer particles (A) are 50 to 85% by weight and the resin (B) is 15 to 50% by weight, further preferably the polymer particles (A) are 50 to 82% by weight and the resin (B) is 18 to 50% by weight, further preferably the polymer particles (A) are 50 to 80% by weight and the resin (B) is 20 to 50% by weight, and particularly preferably the polymer particles (A) are 60 to 80% by weight and the resin (B) is 20 to 40% by weight.

[0330] It should be noted that when a printing ink composition is obtained by method 1, the content of the resin (B) in the printing ink composition (the content of the resin (B) when the total of the polymer particles (A) and the resin (B) is set to 100% by weight) can be said to be the same as the content of the resin (B) in the powder (the content of the resin (B) when the total of the polymer particles (A) and the resin (B) is set to 100% by weight).

[0331] (Anti-blocking agent)

[0332] When the polymer microparticles (A) are used as a powder, the powder preferably further contains an anti-blocking agent. According to this configuration, the obtained powder has (a) excellent anti-blocking properties and (b) excellent dispersibility of the polymer microparticles (A) in a printing ink composition.

[0333] As long as the anti-adhesive agent plays the effect of one embodiment of the present invention, there is no particular limitation. As the anti-adhesive agent, silicon dioxide, titanium oxide, aluminum oxide, zirconium oxide, aluminum silicate, diatomaceous earth, zeolite, kaolin, talc, calcium carbonate, calcium phosphate, barium sulfate, hydrated magnesium silicate (magnesium hydrosilicate) and the like anti-adhesive agents composed of inorganic particles can be cited; anti-adhesive agents composed of organic particles; grease-based anti-adhesive agents such as polyethylene wax, higher fatty acid amide, metal soap, and silicone oil. Among these, the anti-adhesive agent composed of particles is preferred, and the anti-adhesive agent composed of organic particles is more preferred. As the anti-adhesive agent composed of organic particles, it is particularly preferred that the anti-adhesive agent is composed of organic particles of a polymer containing a structural unit of one or more monomers selected from aromatic vinyl monomers, vinyl cyanide monomers, and (meth) acrylate monomers as a structural unit.

[0334] The anti-blocking agent composed of microparticles is generally formed by dispersing the microparticles in a liquid, or is in a colloidal state. The volume average particle size (Mv) of the microparticles in the anti-blocking agent is usually less than 10 μm, preferably 0.05 μm to 10.00 μm. The content of the anti-blocking agent is preferably 0.01 wt% to 5.00 wt%, more preferably 0.50 wt% to 3.00 wt%, relative to the total weight (100 wt%) of the powder.

[0335] (Other optional ingredients)

[0336] The present powder or granule may contain other optional components in addition to the above components as necessary. Examples of other optional components include various components described in the section (2-2-5. Additives) described later.

[0337] The anti-blocking agent and other optional components can be appropriately added in any step of the method for producing the powder or granule. For example, the anti-blocking agent and other optional components can be added to the polymer microparticles (A) or the aqueous suspension (aqueous latex) of the polymer microparticles (A) and the resin (B) before or after coagulation. The anti-blocking agent and other optional components can also be added to the polymer microparticles (A), the resin (B), or the powder or granule containing the polymer microparticles (A) and the resin (B).

[0338] (2-8-2. Method 2)

[0339] (Dispersion (Masterbatch))

[0340] Examples of the method for producing a dispersion, in other words, the step of preparing a dispersion containing polymer microparticles (A) include the following methods (i) and (ii):

[0341] (i) (i-1) obtaining an aqueous latex containing polymer microparticles (A), (i-2) subsequently bringing the aqueous latex into contact with the component (C) and / or a resin (oligomer), and (i-3) subsequently removing unnecessary components such as water from the obtained mixture; and

[0342] (ii) (ii-1) obtaining an aqueous latex containing polymer particles (A), (ii-2) then temporarily extracting the polymer particles (A) in the aqueous latex into an organic solvent, (ii-2) then mixing the obtained organic solvent solution of the polymer particles (A) with the component (C) and / or the resin (oligomer), (ii-3) then removing the organic solvent from the obtained mixture (process). As a method for producing a polymer particle dispersion composition, it is preferred to use the method described in International Publication No. 2005 / 028546.

[0343] A preferred embodiment of the method for producing a dispersion, in other words, the steps of preparing a dispersion containing polymer particles (A), for example, comprises in order: (i) a first step of preparing an aqueous latex containing polymer particles (A) (in other words, preparing polymer particles (A) by emulsion polymerization); (ii) a second step of mixing the aqueous latex containing polymer particles (A) (specifically, a reaction mixture after preparing polymer particles (A) by emulsion polymerization) with an organic solvent having a solubility of 5% by weight to 40% by weight in water at 20° C., further adding an excess of water to the obtained mixture, mixing the obtained mixture, and agglomerating the polymer particles (A); (iii) a third step of separating and recovering the agglomerated polymer particles (A) from the mixture (liquid phase), and then mixing the recovered polymer particles (A) again with an organic solvent to obtain an organic solvent solution of the polymer particles (A); and (iv) a fourth step of further mixing the obtained organic solvent solution with component (C) and / or a resin (oligomer), and then distilling off the organic solvent.

[0344] It should be noted that the method for producing a UV-curable printing ink composition according to one embodiment of the present invention includes a step of mixing the powder and granules described in (Powder and granules) or the dispersion described in (2-8-2. Method 2) with components other than polymer particles (A) and resin (B). The method for producing a printing ink composition according to one embodiment of the present invention may also include a step of mixing the powder and granules obtained by the method for producing a powder and granules described in (Method for producing a powder and granules) or the dispersion described in (2-8-2. Method 2) with components other than polymer particles (A) and resin (B). According to these structures, a printing ink composition in which polymer particles (A) are uniformly dispersed in components other than polymer particles (A) and resin (B) can be obtained.

[0345] Regarding the method for producing the printing ink composition, various components and specific steps are not particularly limited, and the above description can be appropriately cited.

[0346] A specific method for mixing the above-mentioned powder or the dispersion described in (2-8-2. Method 2) with components other than polymer particles (A) and resin (B), in other words, a process for preparing a printing ink composition using the powder or the dispersion is described. This method (process) can be, for example, a method using an autorotation / revolution mixer, a planetary mixer, a disperser, etc. The method of mixing the powder with components other than polymer particles (A) and resin (B) is preferably a method of mixing at 2000 rpm for 40 minutes using an autorotation / revolution mixer.

[0347] (2-4. Application)

[0348] The UV curable printing ink composition according to one embodiment of the present invention can be suitably used as printing ink (printing ink).

[0349] 〔3. Curing film〕

[0350] The cured film according to one embodiment of the present invention is preferably obtained by curing the UV curable printing ink composition described in [2. UV curable printing ink composition]. With this configuration, the cured film has an advantage of being difficult to peel off from the substrate.

[0351] In addition, in recent years, as a light source for curing a UV curable printing ink composition to obtain a cured film, a transition to LEDs that can light up instantly and save electricity is being made. On the other hand, LEDs, etc. have low output compared to UV, etc. Therefore, in order to achieve curing using LEDs, UV curable printing ink compositions need to contain a large amount of photopolymerization initiators and multifunctional monomers, etc., and have better curability (high sensitivity). There is a trade-off between curability and adhesion in curable compositions, and UV curable printing ink compositions containing a large amount of photopolymerization initiators and multifunctional monomers (e.g., low molecular weight compounds (C) having at least three or more polymerizable unsaturated bonds in one molecule) have the disadvantage of low adhesion to the substrate.

[0352] On the other hand, the present printing ink composition solves the above-mentioned problems and has the advantage of excellent adhesion to the substrate. In other words, the present cured film is not easily peeled off from the substrate.

[0353] The light source used when curing the printing ink composition, i.e., when obtaining a cured film from the printing ink composition, is not particularly limited, but a high-pressure mercury lamp, a metal halide lamp, and a UV-LED lamp are preferred. It should be noted that an EB (electron beam) lamp may also be used as the light source. When an EB (electron beam) lamp is used, since the electron beam can be used to decompose organic molecules to initiate free radical polymerization, it is not necessary to contain a photopolymerization initiator.

[0354] The method of printing the UV curable printing ink composition on the substrate is not particularly limited, and examples thereof include offset printing, screen printing, flexographic printing, and IJ printing.

[0355] One embodiment of the present invention may have the following configuration.

[0356] [1] A UV curable printing ink composition comprising polymer particles (A) and a pigment (D),

[0357] The polymer fine particles (A) include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer.

[0358] The elastomer comprises at least one selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber,

[0359] The grafted portion includes a polymer having a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth)acrylate monomer.

[0360] The content of the pigment (D) in the UV curable printing ink composition is 1% by weight or more based on 100% by weight of the UV curable printing ink composition.

[0361] [2] The UV curable printing ink composition according to [1], further comprising a resin (B).

[0362] [3] The UV curable printing ink composition according to [1] or [2], wherein the UV curable printing ink composition further comprises a low molecular weight compound (C),

[0363] The above-mentioned low molecular weight compound (C),

[0364] (i) has at least one polymerizable unsaturated bond in the molecule, and

[0365] (ii) The molecular weight is less than 1000.

[0366] [4] The UV curable printing ink composition according to [3], wherein the low molecular weight compound (C) contains 5 wt % or more of a low molecular weight compound having at least three polymerizable unsaturated bonds in one molecule in 100 wt % of the low molecular weight compound (C).

[0367] [5] A UV-curable printing ink composition according to any one of [1] to [4], wherein the UV-curable printing ink composition further comprises a free radical polymerizable oligomer resin and / or an inert resin (E), and the total content of the free radical polymerizable oligomer resin and the inert resin (E) in the UV-curable printing ink composition is 0.5 wt% or more relative to 100 wt% of the UV-curable printing ink composition.

[0368] [6] A UV-curable printing ink composition according to any one of [1] to [5], wherein the UV-curable printing ink composition further comprises a photopolymerization initiator (F), and the content of the photopolymerization initiator (F) in the UV-curable printing ink composition is 1.0 wt% or more relative to 100 wt% of the UV-curable printing ink composition.

[0369] [7] The UV curable printing ink composition according to any one of [1] to [6], wherein the content of the polymer microparticles (A) is 1.0 wt % or more relative to 100 wt % of the UV curable printing ink composition.

[0370] [8] The UV curable printing ink composition according to any one of [1] to [7], wherein the content of the polymer microparticles (A) is 10.0 wt % or less relative to 100 wt % of the UV curable printing ink composition.

[0371] [9] The UV curable printing ink composition according to any one of [1] to [8], wherein the elastomer is butadiene rubber.

[0372]

[10] The UV curable printing ink composition according to any one of [1] to [9], wherein the volume average particle size of the polymer microparticles (A) is 0.03 μm to 50.00 μm.

[0373]

[11] The UV curable printing ink composition according to [2], wherein the resin (B) is composed of epoxidized soybean oil.

[0374] A cured film obtained by curing the UV curable printing ink composition described in any one of [1] to

[11] .

[0375]

[13] A method for producing a UV curable printing ink composition, comprising the following steps:

[0376] a step of preparing a powder containing polymer microparticles (A); and

[0377] A step of mixing the powder and the pigment (D) to prepare a UV curable printing ink composition;

[0378] The polymer fine particles (A) include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer.

[0379] The elastomer comprises at least one selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber,

[0380] The grafted portion includes a polymer having a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth)acrylate monomer.

[0381] The content of the pigment (D) in the UV curable printing ink composition is 1% by weight or more based on 100% by weight of the UV curable printing ink composition.

[0382]

[14] A method for producing a UV curable printing ink composition, comprising the following steps:

[0383] a step of preparing a dispersion containing polymer microparticles (A), and

[0384] A step of mixing the dispersion with a pigment (D) to prepare a UV curable printing ink composition;

[0385] The polymer fine particles (A) include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer.

[0386] The elastomer is selected from one or more of diene rubber, (meth)acrylate rubber and organosiloxane rubber.

[0387] The grafted portion includes a polymer having a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth)acrylate monomer.

[0388] The content of the pigment (D) in the UV curable printing ink composition is 1% by weight or more based on 100% by weight of the UV curable printing ink composition.

[0389] Example

[0390] Hereinafter, an embodiment of the present invention will be described in further detail according to examples and comparative examples, but the present invention is not limited thereto. An embodiment of the present invention can be appropriately changed and implemented within the scope of the above or the following purport, and they are all included in the technical scope of the present invention. It should be noted that in the following examples and comparative examples, "parts" and "%" refer to parts by weight or weight %.

[0391] <Evaluation Method>

[0392] First, the evaluation method of the printing ink composition prepared according to the examples and comparative examples is described below. In the following description, unless otherwise specified, the term "polymer microparticles" includes polymer microparticles (A) according to one embodiment of the present invention and polymer microparticles outside the scope of the present invention.

[0393] (Method for preparing a cured film composed of a printing ink composition)

[0394] The printing ink composition obtained in each example and comparative example was applied to a PMMA sheet at a thickness of 30 μm, and the PMMA sheet was irradiated with ultraviolet light to cure the printing ink composition, thereby forming a cured film composed of the printing ink composition on the PMMA sheet.

[0395] (Method for measuring the adhesion of a cured film formed by a printing ink composition)

[0396] First, the cured film formed on the PMMA sheet was cut using a cutter to form a chessboard grid (10 vertical × 10 horizontal) consisting of a grid of 1 mm in length × 1 mm in width. Next, a cellophane tape (manufactured by NICHIBAN) was attached to the cured film so that the chessboard-shaped cuts were completely covered. Finally, the cellophane tape was peeled off from the cured film, and the number of grids on the PMMA sheet where the cured film remained in an area of ​​more than 80% of the total area of ​​one grid was visually counted. The adhesion of the printing ink composition was determined based on the number using the following criteria. The results are shown in Table 1.

[0397] 2 (good): The number of grids on which the cured film remains in 80% or more of the total area of ​​one grid on the PMMA sheet is 80 or more

[0398] 1 (OK): The number of grids on the PMMA sheet where the cured film remains in an area of ​​80% or more of the total area of ​​one grid is 50 to 80

[0399] 0 (unacceptable): The number of grids on the PMMA sheet where the cured film remains in 80% or more of the total area of ​​one grid is 50 or less.

[0400] <1. Preparation of elastomer>

[0401] (Production Example 1-1: Preparation of polybutadiene rubber latex (R-1))

[0402] 200 parts by weight of deionized water, 0.03 parts by weight of tripotassium phosphate, 0.002 parts by weight of disodium ethylenediaminetetraacetate (EDTA), 0.001 parts by weight of ferrous sulfate 7-hydrate, and 1.55 parts by weight of sodium dodecylbenzene sulfonate (SDBS) as an emulsifier were added to the pressure polymerizer. Next, the gas inside the pressure polymerizer was replaced with nitrogen while stirring the added raw materials, thereby fully removing oxygen from the inside of the pressure polymerizer. Then, 100 parts by weight of butadiene (Bd) was added to the pressure polymerizer, and the temperature inside the pressure polymerizer was raised to 45°C. Then, 0.03 parts by weight of terpene hydroperoxide (PHP) was added to the pressure polymerizer, and then 0.10 parts by weight of sodium formaldehyde sulfoxylate (SFS) was added to the pressure polymerizer to start polymerization. From the 15th hour after the start of polymerization, devolatilization was carried out under reduced pressure to remove the monomers that were not used in the polymerization and remained, and the polymerization was terminated. During the polymerization, PHP, EDTA and ferrous sulfate 7-hydrate salt are added to the pressure-resistant polymerization vessel in any amount and at any time. Through the polymerization, an aqueous latex (R-1) containing an elastomer with polybutadiene rubber as the main component is obtained. The volume average particle size of the elastomer contained in the obtained aqueous latex is 70 nm.

[0403] (Production Example 1-2: Preparation of polybutadiene rubber latex (R-2))

[0404] The above-obtained polybutadiene rubber latex (R-1) was charged into a pressure polymerizer in the amount of 7 parts by weight in terms of solid content, 200 parts by weight of deionized water, 0.03 parts by weight of tripotassium phosphate, 0.002 parts by weight of EDTA, and 0.001 parts by weight of ferrous sulfate 7 hydrate. Next, the gas inside the pressure polymerizer was replaced with nitrogen while stirring the charged raw materials, thereby fully removing oxygen from the inside of the pressure polymerizer. Then, 93 parts by weight of Bd was charged into the pressure polymerizer, and the temperature inside the pressure polymerizer was raised to 45°C. Then, 0.02 parts by weight of PHP was charged into the pressure polymerizer, and then 0.10 parts by weight of SFS was charged into the pressure polymerizer to start polymerization. From the 30th hour after the start of polymerization, devolatilization was performed under reduced pressure to devolatilize and remove the monomers remaining in the polymerization without being used, and the polymerization was terminated. During the polymerization, PHP, EDTA, ferrous sulfate 7 hydrate, and SDBS were added to the pressure polymerizer in any amount and at any time. By this polymerization, an aqueous latex (R-2) containing an elastomer having polybutadiene rubber as a main component was obtained. The volume average particle size of the elastomer contained in the obtained aqueous latex was 195 nm.

[0405] <2. Preparation of polymer microparticles (A) (polymerization of grafted portion)>

[0406] (Production Example 2-1: Preparation of polymer microparticle latex (L-1))

[0407] 230 parts by weight of the polybutadiene rubber latex (R-2) (including 80 parts by weight of an elastomer having polybutadiene rubber as the main component) and 103 parts by weight of deionized water were added to a glass reactor. Here, the glass reactor had a thermometer, a stirrer, a reflux cooler, a nitrogen inlet, and a monomer addition device. The gas in the glass reactor was replaced with nitrogen, and the raw materials added were stirred at 60°C. Next, 0.003 parts by weight of EDTA, 0.0007 parts by weight of ferrous sulfate 7 hydrate, and 0.14 parts by weight of SFS were added to the glass reactor and stirred for 10 minutes. Then, a mixture of 19 parts by weight of methyl methacrylate (MMA), 1 part by weight of butyl acrylate, and 0.1 parts by weight of tert-butyl hydroperoxide (BHP) was continuously added to the glass reactor over 80 minutes. Then, 0.012 parts by weight of BHP was added to the glass reactor, and the mixture in the glass reactor was further stirred for 1 hour to complete the polymerization. By the above operation, an aqueous latex (L-1) containing polymer particles (A) was obtained. The polymerization conversion rate of the monomer component was 99% or more. The volume average particle size of the polymer particles (A) contained in the obtained aqueous latex was 200 nm. The solid content concentration (concentration of polymer particles (A)) in the obtained aqueous latex (L-1) was 30%.

[0408] <3. Preparation of powder and granules>

[0409] (Production Example 3-1)

[0410] Aqueous emulsion (S-1) (resin (B) content 50%) was prepared by mixing (i) water, (ii) a mixture of 67 parts by weight of epoxidized soybean oil (ADK Cizer O-130P, manufactured by ADEKA Co., Ltd.) as resin (B) and 33 parts by weight of triethylene glycol bis[3-(tert-butyl-4-hydroxy-5-methylphenyl) propionate] (Irganox 245, manufactured by BASF Japan Co., Ltd.) as an antioxidant, and (iii) SDBS as an emulsifier using a homogenizer. 4 parts by weight of calcium acetate was dissolved and 600 parts by weight of ion exchange water adjusted to 70° C. was prepared. Next, 333 parts by weight of the aqueous latex (L-1) corresponding to 100 parts by weight of the polymer microparticles (A) and 22.2 parts by weight of the aqueous emulsion (S-1) (corresponding to 11.1 parts by weight of the resin (B)) are added to 600 parts by weight of the ion exchange water to obtain a slurry containing a coagulated product of the polymer microparticles (A). Next, the slurry is centrifuged and dehydrated to obtain a wet powder as the coagulated product. Furthermore, the obtained wet powder is used to repeat the operation of adding the wet powder to 500 parts by weight of ion exchange water and the operation of centrifuging the obtained mixture for a total of 2 cycles to obtain a wet powder. Finally, the wet powder is dried in a dryer at 50°C for 48 hours to obtain a powder (P-1) containing polymer microparticles (A) and resin (B). The powder (P-1) contains 90% by weight of the polymer microparticles (A) and 10% by weight of the resin (B) when the total of the polymer microparticles (A) and the resin (B) is 100% by weight.

[0411] <4. Preparation of masterbatch>

[0412] (1st step)

[0413] A mixing tank (volume 1 L) equipped with a stirrer was used as an apparatus. In addition, methyl ethyl ketone (MEK) was used as an organic solvent that is partially soluble in water. After the temperature in the mixing tank reached 30°C, 126 parts by weight of MEK were added to the mixing tank. Then, while stirring the MEK in the mixing tank, 143 parts by weight of a latex (L-1) of polymer particles (A) was added to the mixing tank. By uniformly mixing the input raw materials, a mixture (mixture M) containing an aqueous latex of polymer particles (A) and an organic solvent that is partially soluble in water was obtained. Next, while stirring the mixture M, 200 parts by weight of water (469 parts by weight in total) was added to the mixing tank at a supply rate of 80 parts by weight / minute, so that the mixture M was in contact with the water. After the supply of water was completed, the stirring was quickly stopped, and floating coagulations (coagulations of polymer particles (A)) were generated in the water phase, and a slurry solution containing the coagulations was obtained.

[0414] (Second step)

[0415] Next, the agglomerates are separated and recovered from the aqueous phase. Specifically, 350 parts by weight of the aqueous phase are discharged from the outlet at the bottom of the mixing tank, while the agglomerates are left in the mixing tank, thereby obtaining agglomerates. 150 parts by weight of MEK are added to the obtained agglomerates (concentrated solution of polymer particles (A)), and they are mixed to obtain a first organic solvent dispersion containing polymer particles (A). The obtained first organic solvent solution is 277 parts by weight (containing 42.9 parts by weight of polymer particles (A)).

[0416] (Step 3)

[0417] 0.1716 parts by weight of 2,6-di-tert-butyl-p-cresol was added to 277 parts by weight of the obtained first organic solvent dispersion (containing 42.9 parts by weight of polymer microparticles (A)), and the obtained mixture was mixed. Next, 64 parts by weight of acryloylmorpholine (molecular weight 141.17) as a low molecular compound (C) was added to the obtained mixture, and the obtained mixture was mixed to obtain a second organic solvent dispersion. In the third step, when the total amount of polymer microparticles (A) and low molecular compound (C) is 100% by weight, polymer microparticles (A) and low molecular compound (C) are mixed at a mixing ratio of 40% by weight of polymer microparticles (A) and 60% by weight of low molecular compound (C).

[0418] (Step 4)

[0419] MEK was distilled off under reduced pressure from the obtained second organic solvent dispersion to obtain a master batch (M-1). The master batch (M-1) contained 40% by weight of the polymer fine particles (A) and 60% by weight of the low molecular weight compound (C) when the total of the polymer fine particles (A) and the low molecular weight compound (C) was 100% by weight.

[0420] <5. Production of UV Curable Printing Ink Composition>

[0421] (Example 1)

[0422] 2.0 wt % of the powder (P-1) was mixed with 100 wt % of an offset UV ink (FD LPC PR I CM manufactured by Toyo Ink Co., Ltd.) using a three-roll mixer to prepare a printing ink composition.

[0423] The offset UV ink contains 20 wt % or more of the component (C), 1 wt % or more of the component (D) as a pigment, 1.0 wt % or more of the component (E), and 1.0 wt % or more of the component (F) in 100 wt % of the offset UV ink.

[0424] (Example 2)

[0425] 5.0 wt % of the masterbatch (M-1) was mixed with 100 wt % of an offset UV ink (FD LPC PR I CM manufactured by Toyo Ink Co., Ltd.) using a three-roll mixer to prepare a printing ink composition.

[0426] (Example 3)

[0427] A printing ink composition was prepared by mixing 1.0 wt % of the powder (P-1) with 100 wt % of an inkjet UV ink (LH-100 manufactured by Mimaki Engineering Co., Ltd.) using a three-roll mixer.

[0428] The inkjet UV ink contains 20 wt % or more of the component (C), 1 wt % or more of the component (D) as a pigment, 0.5 wt % or more of the component (E), and 1.0 wt % or more of the component (F) in 100 wt % of the inkjet UV ink.

[0429] (Example 4)

[0430] A printing ink composition was prepared by mixing 2.0 wt % of the powder (P-1) with 100 wt % of an inkjet UV ink (LH-100 manufactured by Mimaki Engineering Co., Ltd.) using a three-roll mixer.

[0431] (Comparative Example 1)

[0432] No polymer fine particles (A) or resin (B) were used, and only offset UV ink (FD LPCPR I CM manufactured by Toyo Ink Co., Ltd.) was used.

[0433] (Comparative Example 2)

[0434] No polymer fine particles (A) or resin (B) were used, and only inkjet UV ink (LH-100, manufactured by MIMAKI ENGINEERING CO., LTD.) was used.

[0435]

[0436] Industrial Applicability

[0437] The UV curable printing ink composition according to one embodiment of the present invention can be suitably used as printing ink (printing ink).

Claims

1. A UV curable printing ink composition comprising polymer particles A and pigment D, The polymer microparticles A include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer. The elastomer comprises one or more selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber, The grafted portion comprises a polymer, the polymer comprising a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer and a (meth)acrylate monomer, The content of the pigment D in the UV curable printing ink composition is 1% by weight or more relative to 100% by weight of the UV curable printing ink composition.

2. The UV curable printing ink composition according to claim 1, wherein The UV curable printing ink composition further comprises a resin B.

3. The UV curable printing ink composition according to claim 1, wherein The UV curable printing ink composition further comprises a low molecular weight compound C, The low molecular weight compound C, (i) has at least one polymerizable unsaturated bond in the molecule, and (ii) The molecular weight is less than 1000.

4. The UV curable printing ink composition according to claim 3, wherein The low molecular weight compound C contains 5 wt % or more of a low molecular weight compound having at least three polymerizable unsaturated bonds in one molecule based on 100 wt % of the low molecular weight compound C.

5. The UV curable printing ink composition according to claim 1, wherein The UV curable printing ink composition further comprises a free radical polymerizable oligomer resin and / or an inert resin E, The total content of the radical polymerizable oligomer resin and the inert resin E in the UV curable printing ink composition is 0.5% by weight or more relative to 100% by weight of the UV curable printing ink composition.

6. The UV curable printing ink composition according to claim 1, wherein The UV curable printing ink composition further comprises a photopolymerization initiator F, The content of the photopolymerization initiator F in the UV curable printing ink composition is 1.0% by weight or more relative to 100% by weight of the UV curable printing ink composition.

7. The UV curable printing ink composition according to claim 1, wherein The content of the polymer fine particles A is 1.0 wt % or more relative to 100 wt % of the UV curable printing ink composition.

8. The UV curable printing ink composition according to claim 1, wherein The content of the polymer fine particles A is 10.0 wt % or less based on 100 wt % of the UV curable printing ink composition.

9. The UV curable printing ink composition according to claim 1, wherein The elastomer is butadiene rubber.

10. The UV curable printing ink composition according to claim 1, wherein The volume average particle size of the polymer microparticles A is 0.03 μm to 50.00 μm.

11. The UV curable printing ink composition according to claim 2, wherein: The resin B is composed of epoxidized soybean oil. 12 . A cured film formed by curing the UV curable printing ink composition according to claim 1 .

13. A method for producing a UV curable printing ink composition, comprising the following steps: a step of preparing a powder containing polymer microparticles A, and A step of mixing the powder and the pigment D to prepare a UV curable printing ink composition; The polymer microparticles A include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer. The elastomer comprises one or more selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber, The grafted portion comprises a polymer, the polymer comprising a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer and a (meth)acrylate monomer, The content of the pigment D in the UV curable printing ink composition is 1% by weight or more relative to 100% by weight of the UV curable printing ink composition.

14. A method for producing a UV curable printing ink composition, comprising the following steps: a step of preparing a dispersion containing polymer microparticles A, and A step of mixing the dispersion and pigment D to prepare a UV curable printing ink composition; The polymer microparticles A include a rubber-containing graft copolymer having an elastomer and a graft portion graft-bonded to the elastomer. The elastomer comprises one or more selected from diene rubber, (meth)acrylate rubber and organosiloxane rubber, The grafted portion comprises a polymer, the polymer comprising a structural unit derived from one or more monomers selected from an aromatic vinyl monomer, a vinyl cyanide monomer and a (meth)acrylate monomer, The content of the pigment D in the UV curable printing ink composition is 1% by weight or more relative to 100% by weight of the UV curable printing ink composition.

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