JP7464455B2 - Active energy ray curable ink for lithographic offset printing, its manufacturing method, manufacturing method of cured ink, and printed matter - Google Patents

Description

The present invention relates to an active energy ray-curable ink for lithographic offset printing, a method for producing the same, a method for producing a cured ink product, and a printed product.

Active energy ray-curable printing inks have advantages such as excellent workability due to their ability to cure instantly when exposed to energy rays such as ultraviolet rays, and a relatively low environmental impact because they are basically used without solvents, and are therefore used in a variety of applications such as paper printing and plastic packaging materials. However, active energy ray-curable printing inks also have unique issues, such as poor leveling of the printed surface due to the aforementioned instant curing property, making it difficult to achieve gloss, and poor adhesion to the printed surface compared to oil-based inks, and effective solutions to these issues are required.

As binder resins for active energy ray-curable printing inks, diallyl phthalate resins, which have excellent compatibility with reactive diluents such as dipentaerythritol polyacrylate, and rosin-modified (meth)acrylate resins, which have excellent adhesion to substrates, are known. As inks with excellent printed surface gloss and static fluidity evaluations, printing inks containing acid group-containing urethane (meth)acrylate and metal complex (B) are known. (See, for example, Patent Document 1)

Publication No. WO2019/17270 JP 2017-66348 A

The problem that the present invention aims to solve is to provide an active energy ray-curable ink for lithographic offset printing that is suitable for lithographic offset printing and has even better fluidity and stability.

As a result of intensive research by the inventors to solve the above problems, they discovered that an active energy ray-curable ink for lithographic offset printing containing a monomer having an ethylenically unsaturated double bond, a metal complex, a compound having a polar group, a pigment, and a pigment dispersant solves the above problems.

It is known that metal complexes improve the fluidity of printing inks by coordinating with the polar groups of pigments or polar group-containing pigment dispersants, thereby contributing to stabilizing the dispersion state (see paragraph 0022 of Patent Document 2). In other words, if a certain amount of polar groups is present in the ink, a certain degree of improvement in fluidity can be achieved. In the present invention, it has been discovered that the compound having a polar group is not limited to a pigment dispersant, and that any compound having a polar group can improve fluidity.

That is, the present invention provides an active energy ray-curable ink for lithographic offset printing that contains a monomer having an ethylenically unsaturated double bond, a metal complex, a compound having a polar group, a pigment, and a polar group-containing pigment dispersant.

The present invention also provides a method for producing an active energy ray-curable ink for lithographic offset printing, which contains a monomer having an ethylenically unsaturated double bond, a metal complex, a compound having a polar group, a pigment, and a polar group-containing pigment dispersant, and which comprises mixing and dispersing the metal complex and the compound having a polar group in advance, and then mixing and dispersing the monomer having an ethylenically unsaturated double bond, the pigment, and the polar group-containing pigment dispersant.

The present invention also provides a method for producing a cured ink product, which comprises offset printing using the above-described active energy ray-curable ink for lithographic offset printing, and curing the printed ink using active energy rays.

The present invention also provides a printed matter obtained by the method for producing the ink cured product described above.

The present invention provides an active energy ray-curable ink for lithographic offset printing that has even better fluidity and stability.

(Definition of words)
In the present invention, the term "(meth)acrylate resin" refers to a resin having an acryloyl group, a methacryloyl group, or both in the molecule. The term "(meth)acryloyl group" refers to either an acryloyl group or a methacryloyl group, or both, and the term "(meth)acrylate" is a general term for acrylate and methacrylate.

(Monomer having an ethylenically unsaturated double bond)
The monomer and/or oligomer having an ethylenically unsaturated double bond used in the present invention can be used without any particular limitation as long as it is a monomer and/or oligomer used in the active energy ray curing technical field. In particular, those having a (meth)acryloyl group, a vinyl ether group, or the like as a reactive group are preferred. There is also no particular limitation on the number of reactive groups or molecular weight, and those having a larger number of reactive groups tend to have higher reactivity but higher viscosity and crystallinity, and those having a higher molecular weight tend to have higher viscosity, so that they can be used in appropriate combination according to the desired physical properties. For example, in terms of suitable curing with low energy irradiation such as UV-LED, it is preferred to combine a monomer having a more reactive trifunctional or higher ethylenically unsaturated double bond, and to use a monofunctional or bifunctional monomer alone or in combination as appropriate to obtain the necessary physical properties such as adhesion to a printing substrate and flexibility of the film depending on the application.

Specifically, for example, monofunctional (meth)acrylates, polyfunctional (meth)acrylates, polymerizable oligomers, and other materials that have a proven track record in lamp systems can be used as is in the ultraviolet light-emitting diode system described in this invention.

Examples of monofunctional (meth)acrylates include ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, isoamyl (meth)acrylate, isodecyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxydiethylene glycol ( (meth)acrylate, nonylphenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, diethylaminoethyl (meth)acrylate, nonylphenoxyethyl tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc.

Examples of bifunctional or higher functional (meth)acrylates include 1,4-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene Di(meth)acrylates of dihydric alcohols such as ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and di(meth)acrylates of tris(2-hydroxyethyl)isocyanurate, and di(meth)acrylates obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol Di(meth)acrylates of diols, di(meth)acrylates of diols obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A, poly(meth)acrylates of trihydric or higher polyhydric alcohols such as trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and poly(meth)acrylate of dipentaerythritol. Examples of such poly(meth)acrylates include polyoxyalkylene polyols such as tri(meth)acrylates of triols obtained by adding 3 or more moles of ethylene oxide or propylene oxide to 1 mole of glycerin, di- or tri(meth)acrylates of triols obtained by adding 3 or more moles of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane, and di(meth)acrylates of diols obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A.

Examples of polymerizable oligomers include amine-modified polyether acrylates, amine-modified epoxy acrylates, amine-modified aliphatic acrylates, amine-modified polyester acrylates, amine-modified acrylates such as amino(meth)acrylates, thiol-modified polyester acrylates, thiol-modified acrylates such as thiol(meth)acrylates, polyester(meth)acrylates, polyether(meth)acrylates, polyolefin(meth)acrylates, polystyrene(meth)acrylates, epoxy(meth)acrylates, and urethane(meth)acrylates.

Furthermore, as the monomer and/or oligomer having an ethylenically unsaturated double bond, a tetrafunctional or higher (meth)acrylate is preferably used in printing applications on paper such as fine paper, coated paper, art paper, imitation paper, thin paper, and thick paper, as it contributes greatly to improving curing properties and strength, and is preferably used in the range of 15 to 70 mass% of the total ink solids. On the other hand, in printing applications on plastics, as the crosslink density of the cured coating film increases, the adhesion between the substrate and the cured coating film decreases, so it is necessary to appropriately reduce the content of the tetrafunctional or higher (meth)acrylate. In this case, it is preferable to use the tetrafunctional or higher (meth)acrylate in the range of 0 to 50 mass% of the total ink solids.

(Metal Complex)
The metal complex used in the present invention may also be referred to as a chelating agent.Specific examples include aluminum triethylate aluminum tripropylate, aluminum dipropylate monobutylate, aluminum tributyrate, and other aluminum trialkyl chelates; aluminum acetylacetate dipropylate, aluminum acetylacetate dibutylate, aluminum triacetylacetate, aluminum ethylacetoacetate dipropylate, aluminum trisethylacetoacetate, aluminum octadecylacetoacetate dipropylate, and other aluminum alkyl acetoacetates; titanium tetrapropylate, titanium tetrabutylate, and other titanium alkyl acetoacetates; titanium bis(acetylacetate)dipropylate, and other titanium alkyl acetoacetates; zirconium tetrabutylate, and other zirconium tetraalkyl chelates. Specific examples of these commercially available products include the aluminum organic compound series manufactured by Kawaken Fine Chemical Co., Ltd. ("AMD", "ASBD", "AIPD", "PADM", "aluminum ethoxide", "ALCH", "ALCH-TR", "Aluminum chelate M", "Aluminum chelate D", "Aluminum chelate A, A(W)"); the "Plenact" series manufactured by Ajinomoto Fine-Techno Co., Ltd. ("AL-M", "TTS"); and the "Orgatics" series manufactured by Matsumoto Fine Chemical Co., Ltd. ("AL-3001", "AL-3100", "AL-3200", "AL-3215", "TA-8", "TA-21", "TA-23", "TA-30", "TC-100", "TC-401", "TC-710", "TC-750", "ZA-45", "ZA-65", "AC-150", "ZC-540"), etc. The metal complex (B) may be used alone or in combination of two or more kinds.

Metal compounds such as metal alkoxides and metal acylates can also be used, specifically, alkoxides and acylates of metals selected from the group consisting of aluminum, titanium and zirconium.
Examples of metal alkoxides include aluminum ethylate, aluminum isopropoxide, aluminum disopropylate mono-secondary butylate, aluminum secondary butoxide, tetraisopropyl titanate, tetra-n-butyl titanate, tertiary amyl titanate, tetra-tertiary butyl titanate, tetrastearyl titanate, butyl titanate dimer, tetraoctyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, n-propyl zirconate, and n-butyl zirconate.

Examples of metal acylates include aluminum ethyl acetoacetate diisopropylate, aluminum tris-ethyl acetoacetate, aluminum alkyl acetoacetate diisopropylate, aluminum bis-ethyl acetoacetate monoacetylacetonate, aluminum tris-acetylacetonate, titanium isostearate, zirconium octylate, and zirconium stearate.

The blending amount of the metal complex in the active energy ray-curable ink for lithographic offset printing can be appropriately adjusted depending on the desired ink performance, etc., but in order to obtain a printing ink having particularly high fluidity and excellent gloss of the printed surface, and also having sufficiently high other performances such as misting resistance and emulsification suitability, the blending amount is preferably from 0.01 to 1.5% by mass, and particularly preferably from 0.01 to 1.0% by mass.
The amount of the metal complex is preferably 0.01 mmol to 3.0 mmol, and particularly preferably 0.04 to 2.0 mmol, per 100 g of the active energy ray-curable ink for lithographic offset printing.
The ratio of the substance amount of the polar group of the compound having a polar group described below to the substance amount of the metal complex is preferably 0.5 to 10, and more preferably 0.5 to 3.0.

(Compound having a polar group)
In the present invention, it is essential to use the metal complex in combination with a compound having a polar group.
It is known that metal complexes improve the fluidity of printing inks by coordinating with the polar groups of pigments or polar group-containing pigment dispersants, thereby contributing to stabilization of the dispersion state (see paragraph 0022 of Patent Document 2), and a certain amount of polar groups present in the ink can improve the fluidity to a certain extent. In the present invention, the compound having a polar group is not limited to a pigment dispersant, and any compound having a polar group can improve the fluidity.

The polar group is not particularly limited, and examples thereof include amino groups, hydroxyl groups, carboxyl groups, phosphate groups, epoxy groups, nitrile groups, nitro groups, aldehyde groups, amino groups, and amide groups. These may be used alone or in combination of two or more. Among these, hydroxyl groups and carboxyl groups are preferred.

Among these compounds having a polar group, compounds having a polar group in a monomer, oligomer, or polymer having an ethylenically unsaturated double bond that can become a binder resin are particularly preferred because they can contribute to improving flowability.
Examples of the compound having a polar group in a monomer, oligomer, or polymer having an ethylenically unsaturated double bond include a monomer having an ethylenically unsaturated double bond having a polar group, an epoxy (meth)acrylate obtained by reacting an epoxy compound with a hydroxy (meth)acrylate compound, or the like, and a urethane (meth)acrylate obtained by reacting a polyisocyanate compound with a hydroxy (meth)acrylate compound or an acid group-containing hydroxy compound.

(Monomer Having an Ethylenically Unsaturated Double Bond Having a Polar Group)
Examples of monomers having an ethylenically unsaturated double bond with a polar group include the above-mentioned monomers having an ethylenically unsaturated double bond and having a polar group such as an amino group, a hydroxyl group, a carboxyl group, a phosphoric acid group, an epoxy group, a nitrile group, a nitro group, an aldehyde group, an amino group, or an amide group. In addition to the above-mentioned monomers having an ethylenically unsaturated double bond and having a polar group such as an amino group, a hydroxyl group, a carboxyl group, a phosphoric acid group, an epoxy group, a nitrile group, a nitro group, an aldehyde group, an amino group, or an amide group, examples of monomers having an ethylenically unsaturated double bond include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, 2-hydroxy(meth)acrylate, 2-hydroxypropyl(meth)acrylate, glycidyl(meth)acrylate, allyl glycidyl ether, dimethylaminoethyl(meth)acrylate, vinylpyridine, t-butylaminoethyl(meth)acrylate, (meth)acrylamide, maleimide, allyl alcohol, and oxazoline. The above compounds can be used alone or in combination of two or more kinds. Of these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred.

(Epoxy (meth)acrylate)
The epoxy (meth)acrylate has a hydroxyl group in the molecule, and an example thereof is one obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a basic catalyst according to a conventional method. Examples of epoxy compounds that can be used as raw materials for synthesizing epoxy (meth)acrylates include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, 2,2'-diallyl bisphenol A type epoxy resins, hydrogenated bisphenol type epoxy resins, propylene oxide-added bisphenol A type epoxy resins, resorcinol type epoxy resins, biphenyl type epoxy resins, sulfide type epoxy resins, diphenyl ether type epoxy resins, dicyclopentadiene type epoxy resins, naphthalene type epoxy resins, phenol novolac type epoxy resins, ortho-cresol novolac type epoxy resins, dicyclopentadiene novolac type epoxy resins, biphenyl novolac type epoxy resins, naphthalene phenol novolac type epoxy resins, glycidyl amine type epoxy resins, alkyl polyol type epoxy resins, rubber modified type epoxy resins, glycidyl ester compounds, bisphenol A type episulfide resins, and the like.

(Urethane (meth)acrylate)
An example of the urethane (meth)acrylate is an acid group-containing urethane (meth)acrylate obtained by reacting a polyisocyanate compound (a1), a hydroxy (meth)acrylate compound (a2) and an acid group-containing hydroxy compound (a3) according to a standard method.

Examples of the polyisocyanate compound (a1) include aliphatic diisocyanate compounds such as butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate; alicyclic diisocyanate compounds such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate, and 1,5-naphthalene diisocyanate; polyisocyanate compounds having a repeating structure represented by the following structural formula (1); and isocyanurate modified products, biuret modified products, and allophanate modified products of these. These may be used alone or in combination of two or more types.

［式中、Ｒ^１はそれぞれ独立に水素原子、炭素原子数１～６の炭化水素基の何れかである。Ｒ^２はそれぞれ独立に炭素原子数１～４のアルキル基、又は構造式（１）で表される構造部位と＊印が付されたメチレン基を介して連結する結合点の何れかである。ｌは０又は１～３の整数であり、ｍは１以上の整数である。］

[In the formula, R ¹ is independently either a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms. R ² is independently either an alkyl group having 1 to 4 carbon atoms, or a bonding point connecting the structural portion represented by structural formula (1) via a methylene group marked with an *. l is 0 or an integer of 1 to 3, and m is an integer of 1 or more.]

Among the polyisocyanate compounds (a1), it is preferable to use a polyisocyanate compound having a molecular structure represented by the structural formula (1) or a polyisocyanate compound having an average number of functional groups of 3 or more, such as an isocyanurate-modified product of various diisocyanate compounds, since a printing ink having excellent fluidity and gloss of the printed surface as well as excellent general printing suitability such as misting resistance and emulsification suitability can be obtained. In particular, the proportion of the polyisocyanate compound having an average number of functional groups of 3 or more in the polyisocyanate compound (a1) is preferably 70% by mass or more, more preferably 90% by mass or more. In addition, when the polyisocyanate compound is an isocyanurate-modified product, the raw material diisocyanate compound is preferably an aliphatic or alicyclic diisocyanate compound, and an aliphatic diisocyanate compound is particularly preferred.

The hydroxy(meth)acrylate compound (a2) may be, for example, an aliphatic hydroxymono(meth)acrylate compound such as hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, or hydroxybutylacrylate; an aliphatic hydroxypoly(meth)acrylate compound such as glycerin di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, or dipentaerythritol penta(meth)acrylate; 4-hydroxyphenyl acrylate, β-hydroxyphenethyl acrylate, 4-hydroxyphenethyl acrylate, 1-phenyl-2-hydroxyethyl acrylate, or 3-hydroxy-4-acetylphenyl acrylate. Examples of the hydroxy(meth)acrylate compounds include aromatic hydroxymono(meth)acrylate compounds such as 2-hydroxy-3-phenoxypropyl acrylate, polyoxyalkylene-modified monohydroxy(meth)acrylate compounds obtained by ring-opening polymerization of the above-mentioned various hydroxy(meth)acrylate compounds with various cyclic ether compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether, and lactone-modified hydroxy(meth)acrylate compounds obtained by polycondensation of the above-mentioned monohydroxy(meth)acrylate compounds with lactone compounds such as ε-caprolactone. These compounds may be used alone or in combination of two or more.

Among the hydroxy(meth)acrylate compounds (a2), the aliphatic hydroxymono(meth)acrylate compounds, the aliphatic hydroxypoly(meth)acrylate compounds, and their polyoxyalkylene-modified or lactone-modified derivatives are preferred, since they provide printing inks that are excellent in fluidity and gloss of the printed surface, as well as in general printing suitability such as misting resistance and emulsification suitability, and lactone-modified aliphatic hydroxy(meth)acrylate compounds are more preferred, with lactone-modified aliphatic hydroxymono(meth)acrylate compounds being particularly preferred. Furthermore, the proportion of the lactone-modified aliphatic hydroxymono(meth)acrylate compounds in the hydroxy(meth)acrylate compounds (a2) is preferably 70% by mass or more, and more preferably 90% by mass or more.

The number of carboxyl groups and hydroxyl groups and other specific structures of the acid group-containing hydroxyl compound (a3) are not particularly limited as long as the acid group, such as a carboxyl group, and a hydroxyl group are contained in the molecular structure. The acid group-containing hydroxyl compounds (a3) may be used alone or in combination of two or more. Among them, aliphatic compounds are preferred because they provide a printing ink with even better fluidity and gloss on the printed surface, and compounds having 1 to 3 carboxyl groups and 1 to 3 hydroxyl groups on an aliphatic hydrocarbon having 2 to 20 carbon atoms are more preferred. Specific examples of such compounds include monohydroxy compounds such as glycolic acid, lactic acid, hydroxybutanoic acid, hydroxypentanoic acid, hydroxyhexanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, hydroxydodecanoic acid, hydroxytetradecanoic acid, hydroxyhexadecanoic acid, hydroxyheptadecanoic acid, hydroxyoctadecanoic acid (hydroxystearic acid), and ricinoleic acid; dihydroxy compounds such as glyceric acid, 2-(hydroxymethyl)-3-hydroxypropionic acid, 2-(dihydroxymethyl)propionic acid, dimethylolpropionic acid, and 3,3-dimethylolpropionic acid; and trihydroxy compounds such as 3-hydroxy-2,2-bis(hydroxymethyl)propionic acid.

The acid group-containing urethane (meth)acrylate may be a product obtained by using other reaction raw materials in combination with the polyisocyanate compound (a1), the hydroxy (meth)acrylate compound (a2), and the acid group-containing hydroxy compound (a3). Examples of the other reaction raw materials include polyol compounds other than the hydroxy (meth)acrylate compound (a2) and the acid group-containing hydroxy compound (a3). Examples of the polyol compounds include aliphatic polyol compounds such as ethylene glycol, propylene glycol, butanediol, hexanediol, glycerin, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipentaerythritol; aromatic polyol compounds such as biphenol and bisphenol; (poly)oxyalkylene modified compounds in which a (poly)oxyalkylene chain such as a (poly)oxyethylene chain, a (poly)oxypropylene chain, or a (poly)oxytetramethylene chain has been introduced into the molecular structure of the various polyol compounds; and lactone modified compounds in which a (poly)lactone structure has been introduced into the molecular structure of the various polyol compounds.

When the other reaction raw materials are used, the effects of the present invention are fully exhibited, so that the proportion of the total mass of the polyisocyanate compound (a1), the hydroxy(meth)acrylate compound (a2) and the acid group-containing hydroxy compound (a3) in the reaction raw materials of the acid group-containing urethane (meth)acrylate is preferably 70 mass% or more, and more preferably 90 mass% or more.

The acid value of the acid group-containing urethane (meth)acrylate is preferably in the range of 1 to 50 mgKOH/g, more preferably in the range of 3 to 40 mgKOH/g, and particularly preferably in the range of 3 to 35 mgKOH/g, since this provides a printing ink with even better fluidity and gloss on the printed surface. In the present invention, the acid value of the resin is a value measured by the neutralization titration method of JIS K 0070 (1992).

The mass average molecular weight (Mw) of the acid group-containing urethane (meth)acrylate is preferably in the range of 1,000 to 25,000, and more preferably in the range of 1,000 to 10,000, since this provides a printing ink with superior fluidity and gloss of the printed surface when used in printing ink applications.

In this invention, the molecular weight of the resin is a value measured by gel permeation chromatography (GPC) under the following conditions:

Measuring device: Tosoh Corporation HLC-8220GPC
Column: TSK-GUARD COLUMN SuperHZ-L manufactured by Tosoh Corporation
+ Tosoh Corporation TSK-GEL Super HZM-M x 4
Detector: RI (differential refractometer)
Data processing: Multistation GPC-8020 model II manufactured by Tosoh Corporation
Measurement conditions: Column temperature: 40°C
Solvent Tetrahydrofuran
Flow rate: 0.35 ml/min. Standard: Monodisperse polystyrene Sample: 100 μl of a tetrahydrofuran solution containing 0.2% by mass of resin solids filtered through a microfilter

(Polar group concentration in ink derived from urethane acrylate)
The amount of the acid group derived from the urethane acrylate in 100 g of the active energy ray-curable ink for lithographic offset printing is preferably 0.01 to 3.0 mmol, and particularly preferably 0.03 to 1.5 mmol in order to improve the fluidity of the ink.

(Other binder resins)
In the present invention, the ink may contain a resin other than those mentioned above that can serve as a binder. The binder resin mentioned here refers to any resin having appropriate pigment affinity and dispersibility and rheological properties required for printing inks. For example, examples of non-reactive resins include diallyl phthalate resin, epoxy resin, epoxy ester resin, polyurethane resin, polyester resin, petroleum resin, rosin ester resin, poly(meth)acrylic acid ester, cellulose derivative, vinyl chloride-vinyl acetate copolymer, polyamide resin, polyvinyl acetal resin, butadiene-acrylonitrile copolymer, aldehyde resin, ketone resin, ketone-formaldehyde resin, etc., and epoxy (meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate, etc. other than those mentioned above may also be used.

The diallyl phthalate resin has three isomers, namely, ortho, iso and tere, and diallyl orthophthalate resin (often simply referred to as diallyl phthalate resin) and diallyl isophthalate resin can be used as the binder resin in the active energy ray curable ink for lithographic offset printing of the present invention.
The diallyl isophthalate resin may be, for example, a composition containing a polybasic acid such as phthalic acid as a base agent, allyl alcohol as a curing agent, and a crosslinking agent, etc. Examples of the crosslinking agent include styrene and vinyl acetate.
Diallyl orthophthalate resin and diallyl isophthalate resin are particularly useful for imparting excellent paper peeling properties, emulsification resistance, and long-run printability.
Specific examples of the diallyl orthophthalate resin include Daiso DAP A (manufactured by Osaka Soda Co., Ltd.), and examples of the diallyl isophthalate resin include Daiso Isodap (manufactured by Osaka Soda Co., Ltd.).

(Pigment)
[0043] Examples of the pigment used in the present invention include publicly known organic pigments for coloring, such as the organic pigments for printing inks listed in "Organic Pigment Handbook" (author: Hashimoto Isao, publisher: Color Office, first edition, 2006). Usable pigments include soluble azo pigments, insoluble azo pigments, condensed azo pigments, metal phthalocyanine pigments, metal-free phthalocyanine pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, diketopyrrolopyrrole pigments, carbon black pigments, and other polycyclic pigments.

In addition, inorganic fine particles may be used as an extender pigment in the active energy ray curable ink for lithographic offset printing of the present invention. Examples of inorganic fine particles include inorganic coloring pigments such as titanium oxide, graphite, and zinc oxide; inorganic extender pigments such as lime carbonate powder, precipitated calcium carbonate, gypsum, clay (China Clay), silica powder, diatomaceous earth, talc, kaolin, alumina white, barium sulfate, aluminum stearate, magnesium carbonate, baryte powder, and grinding powder; and inorganic pigments such as silicone and glass beads. By using these inorganic fine particles in the ink in the range of 0.1 to 60% by weight, it is possible to adjust the coloring and rheological properties of the ink.

(Pigment Dispersant)
The pigment dispersant used in the present invention is preferably a polar group-containing pigment dispersant (hereinafter sometimes referred to as a polar group-containing pigment dispersant) since it can further improve the dispersibility of the pigment and the ink fluidity. Examples of the polar group include an acidic group, a basic group, and other functional groups.
Examples of the acidic group include a carboxyl group, a sulfo group, and a phosphate group. Examples of the basic group include a functional group having a nitrogen atom, such as an amino group, an amide group, and an imide group. Examples of other functional groups include a hydroxyl group, a nitro group, and a cyano group. The polar group-containing pigment dispersant may have two or more types of polar groups. Among these, a basic group-containing pigment dispersant (hereinafter sometimes referred to as a basic group-containing pigment dispersant) in which the polar group is a basic group is preferred.
The polar group-containing pigment dispersant does not include a diallyl phthalate resin, a photopolymerization initiator containing a polar group, or a catalyst for the photopolymerization initiator.

In particular, it is particularly preferable to use the metal complex, the compound having the polar group, and a basic group-containing pigment dispersant having an acid value in combination, as this further improves the fluidity of the active energy ray-curable ink for lithographic offset printing.

In the present invention, examples of the basic group-containing pigment dispersant include commercially available dispersants known as basic dispersants. Among dispersants known as basic dispersants, it is preferable to use a basic dispersant that has an acid value and at least a basic adsorption group. Examples of acid values of commercially available dispersants that satisfy the above conditions include Solsperse 24000 (acid value 29 mg KOH/g), Solsperse 26000 (acid value 50 mg KOH/g), Solsperse 32000 (acid value 18 mg KOH/g), Solsperse 33000 (acid value 27 mg KOH/g), Solsperse 39000 (acid value 17.5 mg KOH/g) (all manufactured by Lubrizol Corporation), Ajisper PB821 (acid value 17 mg KOH/g), PB822 (14 mg KOH/g), PB824 (acid value 21 mg KOH/g), and PB881 (acid value 17 mg KOH/g) (all manufactured by Ajinomoto Fine-Techno Co., Ltd.).

Among these, for the active energy ray-curable ink for lithographic offset printing of the present invention, the acid value of the basic group-containing pigment dispersant is preferably 10 to 55 mgKOH/g, and particularly preferably 10 to 35 mgKOH/g.

(Photopolymerization initiator)
The photopolymerization initiator used in the present invention is not particularly limited, and a general-purpose photopolymerization initiator can be used in combination. Specifically, for example, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, phenyl glyoxylic acid methyl Esters, oxyphenylacetic acid, mixture of 2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic acid, 2-(2-hydroxyethoxy)ethyl ester, 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), 2-methyl-1-(4-methylthiophenyl)-2-morpholino Compounds such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-benzyl-2-dimethylamino-1-(4-piperidinophenyl)-butan-1-one, 1-([1,1'-biphenyl]-4-yl)-2-methyl-2-morpholinopropan-1-one, 1-(4-methoxyphenyl)-2-methyl-2-(4-morpholinyl-1-propanone, 1-(9,9-dibutyl-9H-fluoren-2-yl)-2-methyl-2-morpholinopropan-1-one, etc.

Other examples include acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and ethyl-(2,4,6-trimethylbenzoyl)phenylphosphineate.

Other examples include thioxanthone compounds such as 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dichlorothioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-hydroxy-3-(3,4-dimethyl-9-oxo-9Hthioxanthone-2-yloxy-N,N,N-trimethyl-1-propanamine hydrochloride.

Other examples include 4,4'-dialkylaminobenzophenones such as 4,4'-bis-(dimethylamino)benzophenone and 4,4'-bis-(diethylamino)benzophenone, and benzophenone compounds such as 4-benzoyl-4'-methyldiphenyl sulfide.

Other examples include benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 2,3,4-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, methyl-o-benzoylbenzoate, [4-(methylphenylthio)phenyl]phenylmethanone, diethoxyacetophenone, dibutoxyacetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and benzoin normal butyl ether.
The general-purpose photopolymerization initiators may be used alone or in combination of several kinds.

[Sensitizers/Photoinitiator assistants]
In the present invention, a photosensitizer or a photoinitiator assistant such as a tertiary amine may be used in combination, and is preferred. The photosensitizer is not particularly limited, but examples thereof include thioxanthone-based, benzophenone-based such as 4,4'-bis(diethylamino)benzophenone, anthraquinone-based, and coumarin-based.
Among these, thioxanthone compounds such as 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-chlorothioxanthone, and 2-isopropylthioxanthone, and 4,4'-dialkylaminobenzophenones such as Michler's ketone and 4,4'-bis-(diethylamino)benzophenone are particularly preferred, and from the viewpoints of performance, safety, availability, and the like, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 4,4'-bis-(diethylamino)benzophenone are particularly preferred.

When a sensitizer or photoinitiator aid is used in combination, the amount is preferably 0.05 to 10% by mass, more preferably 0.1 to 7.0% by mass, based on the total ink solids. If the amount is less than 0.05% by mass, sufficient improvement in curability cannot be obtained, and if the amount is more than 10% by mass, the hue of the cured coating film may become unacceptably yellowish, the sensitizer may precipitate, or the fluidity of the ink may decrease significantly.

On the other hand, tertiary amines include, but are not limited to, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N,N-dihydroxyethylaniline, triethylamine, and N,N-dimethylhexylamine, 2-ethylhexyl-4-(dimethylamino)benzoate, 2-butoxyethyl-4-(dimethylamino)benzoate, etc., which reduce polymerization inhibition caused by oxygen, react with thioxanthones and 4,4'-dialkylaminobenzophenones activated by ultraviolet light to become active radical donors, improve the curing performance of the ink, and improve the solubility of the photopolymerization initiator. The amount of tertiary amine is preferably 0.1 to 10% by mass, more preferably 0.1 to 5.0% by mass, based on the total solid content of the ink.

In addition, for applications requiring high hygiene, high molecular weight compounds in which multiple photosensitizers or tertiary amines are branched with polyhydric alcohols, etc., within one molecule can also be used as appropriate.

(Other additives)
Examples of other additives that impart abrasion resistance, anti-blocking properties, smoothness, and anti-scratch properties include natural waxes such as carnauba wax, Japan wax, lanolin, montan wax, paraffin wax, and microcrystalline wax, and synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax, and silicone compounds.

Additives that impart storage stability to inks include, for example, polymerization inhibitors such as (alkyl)phenols, hydroquinone, catechol, resorcin, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-tert-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cupferron, aluminum N-nitrosophenylhydroxylamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino-1,3-dimethylbutylidene)aniline oxide, dibutylcresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime, and cyclohexanone oxime.

Additives such as fluorescent brighteners, ultraviolet absorbers, infrared absorbers, and antibacterial agents can also be added depending on the required performance.

The active energy ray curable ink for lithographic offset printing of the present invention can be used without a solvent, or an appropriate solvent can be used as necessary. There are no particular limitations on the solvent as long as it does not react with the above-mentioned components, and it can be used alone or in combination of two or more kinds.

(Method of manufacturing active energy ray curable ink for lithographic offset printing)
The active energy ray-curable ink for lithographic offset printing of the present invention may be produced by a method similar to that of the conventional method, for example, by mixing ink composition components such as the pigment, resin, acrylic monomer or oligomer, polymerization inhibitor, initiator, sensitizer such as an amine compound, and other additives at a temperature between room temperature and 100° C. using a milling, mixing and adjustment machine such as a kneader, a three-roll mill, an attritor, a sand mill or a gate mixer.

Furthermore, in the method for producing an active energy ray-curable ink for lithographic offset printing of the present invention, if the metal complex and the compound having a polar group are mixed and dispersed in advance, and then the monomer having an ethylenically unsaturated double bond, the pigment, and the polar group-containing pigment dispersant are mixed and dispersed, the fluidity of the active energy ray-curable ink for lithographic offset printing can be further improved.
Although the exact reason is unclear, it is presumed that by mixing and dispersing the metal complex and the compound having a polar group in advance (because it is known that the metal complex and the polar group of the compound having a polar group react with each other), a reaction product is generated in which part of the metal complex and the compound having a polar group react with each other, and this reaction product contributes to fluidity.

More specifically, the method for producing the active energy ray-curable ink for lithographic offset printing of the present invention is preferably a method including the following steps (1) to (3), where (1) and (2) are collectively referred to as premixing, and (3) is referred to as main dispersion.
(1) The metal complex and the compound having a polar group are mixed and dispersed in advance to obtain a composition X. (As described above, it is presumed that a reaction product is generated by a reaction between a part of the metal complex and the compound having a polar group.)
(2) The composition X obtained in (1), the metal complex containing the reaction product, and the compound having a polar group are stirred and mixed into a composition, and a polar group-containing pigment dispersant, pigment, binder resin, photopolymerization initiator, and other additives are added to the composition under stirring at 50 to 70° C. to obtain a dispersion.
(3) Thereafter, the mixture is dispersed using a triple roll mill, a bead mill, or other known dispersing machine to obtain a dispersion, i.e., an ink, in which the pigment particle size has been adjusted to a value suitable for offset printing.
By using this manufacturing method, the fluidity of the active energy ray-curable ink for lithographic offset printing can be further improved.
The peripheral speed of the stirring blades of the disperser used in this production method and the stirring time can be appropriately adjusted depending on the volume of the tank in which the mixture is placed, but the ratio d/D of the diameter of the stirring blades of the dissolver to the diameter of the tank is preferably 0.2 to 0.5, and the peripheral speed of the dissolver is preferably in the range of 20 to 30 m/s.

(Method of manufacturing cured ink, printed matter)
The ink cured product of the present invention is characterized in that an active energy ray-curable ink for lithographic offset printing is offset printed on a substrate, and the printed ink is cured with active energy rays.

(Printing method)
As described above, the active energy ray-curable ink for lithographic offset printing of the present invention can be preferably used in a lithographic offset printing method that combines lithographic printing (lithographic printing using dampening water or waterless lithographic printing not using dampening water) with a transfer (offset) method in which the ink applied to the plate is transferred to an intermediate transfer body such as a blanket, and then printed on a substrate.

Inks that can be used in lithographic offset printing have a relatively high viscosity of 5 to 100 Pa·s, and the mechanism of a lithographic printing press is such that ink is supplied from the ink fountain of the press to the image areas of the plate via multiple rollers, and in lithographic printing that uses dampening water, dampening water is supplied to the non-image areas to repel the ink, forming an image on the paper.

In lithographic printing using dampening water, the emulsification balance between the ink and dampening water is important, and the ink is also required to be emulsification-resistant and suitable for high-speed printing. If the ink has too much emulsification, it will easily adhere to non-image areas, causing smearing, reduced print density, emulsified ink tangling on the water bar roller, and other printing defects such as flying and ink accumulation on the blanket outside the paper feed. If the emulsification level is low, when printing with few images, smearing of non-image areas, known as background staining, becomes noticeable, making it difficult to print stably.

From this viewpoint, in the active energy ray-curable ink for lithographic offset printing of the present invention, the acid value of the resins and monomers used in the ink other than the compound having a polar group and the pigment dispersant is preferably in the range of 1.0 to 10.0, and more preferably in the range of 1.0 to 2.0. If the ink acid value exceeds 10.0, the ink is more likely to emulsify, and if the amount of dampening water supplied during printing is increased, the density of the printed matter decreases, and the emulsified ink is more likely to adhere to the non-image areas on the plate that have been hydrophilically treated, causing staining called scumming in the non-image areas of the printed matter. On the other hand, if the ink acid value is below 1.0, the fluidity of the ink and the gloss of the printed matter decrease.

Specific aspects will be explained below.

(Printing substrate)
The printing substrate used in the printed matter of the present invention is not particularly limited, and examples thereof include paper such as fine paper, coated paper, art paper, imitation paper, thin paper, and thick paper, films or sheets of polyester resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl alcohol, polyethylene, polypropylene, polyacrylonitrile, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer, nylon, polylactic acid, polycarbonate, and the like, cellophane, aluminum foil, and various other substrates that have conventionally been used as printing substrates.

Examples of plastic substrates and soft packaging substrates include polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polylactic acid (PLA); polyolefin resin films such as OPP (biaxially oriented polypropylene) film; polystyrene resin films; polyamide resin films such as nylon 6 and poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin films; polyacrylonitrile resin films; polyimide resin films; and laminates thereof (for example, nylon 6/MXD6/nylon 6, nylon 6/ethylene-vinyl alcohol copolymer, and polyolefin resin films such as polyethylene, such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), which are particularly used as sealant films, acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, copolymer polypropylene, VMCPP (aluminum-vapor-deposited non-oriented polypropylene), VMLDPE (aluminum-vapor-deposited low-density polyethylene), ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, and ionomer.
Further, in order to impart various functionalities such as a barrier function to the resin film, examples of the composite film include a soft metal foil such as an aluminum foil, a vapor deposition layer such as an aluminum vapor deposition layer, a silica vapor deposition layer, an alumina vapor deposition layer, or a silica-alumina binary vapor deposition layer, and an organic barrier layer made of a vinylidene chloride resin, a modified polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, or an MXD nylon.

Among the above-mentioned substrates, the resin films used for plastic substrates and flexible packaging substrates generally have low surface energy and do not wet well with active energy ray-curable inks, which can easily cause poor adhesion. For this reason, it is preferable to generate a corona discharge by applying a high-frequency, high-voltage output supplied by a high-frequency power source between a discharge electrode and an earth roll provided in a corona treatment device, and pass the film under this corona discharge to improve the surface energy of the substrate.

It is also preferable to apply an adhesion imparting agent, generally called a primer or anchor (coating agent), to the plastic substrate or flexible packaging substrate in advance.

Onto these substrates, the active energy ray curable ink for lithographic offset printing of the present invention is transfer-printed by lithographic offset printing to provide an ink layer.
Lithographic offset printing generally involves overprinting using color process inks or special color inks in a single color or multiple colors.
Lithographic offset printing presses are manufactured and sold by many printing press manufacturers, examples of which include Heidelberg, Komori Corporation, Ryobi MHI Graphic Technology, Manroland, KBA, etc. The present invention can be suitably used in any paper supply system, including sheet-fed offset printing presses that use sheet-form printing paper and offset web printing presses that use reel-form printing paper. More specifically, examples of offset printing presses include the Speedmaster series manufactured by Heidelberg, the Lithrone series manufactured by Komori Corporation, and the RMGT series manufactured by Ryobi MHI Graphic Technology.

(light source)
Examples of active energy sources used for the purpose of curing the printed ink include ultraviolet light from a germicidal lamp, an ultraviolet fluorescent lamp, an ultraviolet light emitting diode (UV-LED), a carbon arc, a xenon lamp, a high pressure mercury lamp for copying, a medium or high pressure mercury lamp, an ultra-high pressure mercury lamp, an electrodeless lamp, a metal halide lamp, natural light, etc. The ultraviolet light emitting diode (UV-LED) preferably has a peak wavelength of about 350 to 420 nm, more preferably in the range of 350 to 400 nm, and has an integrated light quantity of about 5 mJ/cm ² to 200 mJ/cm ² , more preferably 10 to 100 mJ/cm.

The irradiation intensity (mW/cm ² ) of ultraviolet light irradiated from the ultraviolet light-emitting diode light source to the UV-curable composition on the printing substrate is not particularly specified because the appropriate irradiation intensity range varies depending on various conditions such as the number of ultraviolet light-emitting diode light sources arranged in the printing direction and the irradiation distance from the light source to the composition, but since the moving speed of the printing substrate in the printing method described in the present invention is about 60 to 400 m/min., it is preferable that the irradiation intensity is such that the integrated light amount value is about the above-mentioned level for the UV-curable composition on the printing substrate moving at that printing speed.

The active energy ray curable printing ink of the present invention is applied to lithographic offset printing, which normally uses dampening water, but can also be suitably used in waterless printing, which does not use dampening water. The active energy ray curable printing ink for lithographic offset printing of the present invention is also applied to printed materials such as forms, various books, various packaging printed materials such as carton paper, various plastic printed materials, seal/label printed materials, fine art printed materials, and metal printed materials (fine art printed materials, printed materials on beverage cans, printed materials on canned foods, etc.).

The present invention will be described in more detail below with reference to examples. Note that the present invention is not limited to these examples.

Infrared absorption spectrum measurement)
[Model] JASCO Corporation FT/IR-4100
[Measurement conditions] Completion of the reaction was confirmed by checking the infrared absorption spectrum at 2250 cm ^-1 which indicates an isocyanate group.

Measurement of Mass Average Molecular Weight (Mw) The mass average molecular weight (Mw) was measured by gel permeation chromatography (GPC) under the following conditions.
Measuring device: Tosoh Corporation HLC-8220GPC
Column: TSK-GUARDCOLUMN SuperHZ-L manufactured by Tosoh Corporation + TSK-GEL SuperHZM-Mx4 manufactured by Tosoh Corporation
Detector: RI (differential refractometer)
Data processing: Multistation GPC-8020 model II, manufactured by Tosoh Corporation
Measurement conditions: Column temperature: 40°C
Solvent Tetrahydrofuran
Flow rate: 0.35 ml/min. Standard: monodisperse polystyrene Sample: 0.2% by mass of tetrahydrofuran solution (resin solid content equivalent) filtered through a microfilter (100 μl)

Acid value measurement conditions
The measurement was performed by the neutralization titration method of JIS K 0070 (1992).

(Production Example 1) Production of a compound (A-1) having a polar group In a flask equipped with a stirrer, a gas inlet tube, a condenser and a thermometer, 187.1 parts by mass of lactone-modified hydroxyethyl acrylate ("Placcel FA2D" manufactured by Daicel Corporation), 16.1 parts by mass of 12-hydroxystearic acid, and 0.17 parts by mass of N-nitroso-N-phenylhydroxylamine aluminum were added and heated to 65°C. 108.6 parts by mass of isocyanurate-modified hexamethylene diisocyanate ("Sumidur N3300" manufactured by Sumika Covestro Urethane Co., Ltd.) were added dropwise over 1 hour. After completion of the dropwise addition, the mixture was heated to 95°C and reacted for 2 hours. It was confirmed that the infrared absorption spectrum at 2250 cm ^-1 indicating an isocyanate group had disappeared, and a compound (A-1) having a polar group, which is a urethane (meth)acrylate resin, was obtained. The compound (A-1) having a polar group had a mass average molecular weight (Mw) of 4,477 and an acid value of 11.2 mgKOH/g.

(Production Example 2) Production of a compound (A-2) having a polar group A flask equipped with a stirrer, a gas inlet tube, a condenser and a thermometer was charged with 143.3 parts by mass of lactone-modified hydroxyethyl acrylate ("Placcel FA2D" manufactured by Daicel Corporation), 6.0 parts by mass of 12-hydroxystearic acid, and 0.12 parts by mass of N-nitroso-N-phenylhydroxylamine aluminum, and heated to 65°C. 79.8 parts by mass of isocyanurate-modified hexamethylene diisocyanate ("Sumidur N3300" manufactured by Sumika Covestro Urethane Co., Ltd.) was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was heated to 95°C and reacted for 2 hours. It was confirmed that the infrared absorption spectrum at 2250 cm ^-1 indicating an isocyanate group had disappeared, and a compound (A-2) having a polar group, which is a urethane (meth)acrylate resin, was obtained. The compound (A-2) having a polar group had a mass average molecular weight (Mw) of 4,275 and an acid value of 6.0 mgKOH/g.

(Production Example 3) Production of a compound (A-3) having a polar group A flask equipped with a stirrer, a gas inlet tube, a condenser and a thermometer was charged with 116.4 parts by mass of lactone-modified hydroxyethyl acrylate (Daicel Corporation's "Placcel FA2D"), 31.3 parts by mass of 12-hydroxystearic acid, and 0.12 parts by mass of N-nitroso-N-phenylhydroxylamine aluminum, and heated to 65°C. 79.1 parts by mass of isocyanurate-modified hexamethylene diisocyanate (Sumidur N3300 manufactured by Sumika Covestro Urethane Co., Ltd.) was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was heated to 95°C and reacted for 2 hours. It was confirmed that the infrared absorption spectrum at 2250 cm ^-1 indicating an isocyanate group had disappeared, and a compound (A-3) having a polar group, which is a urethane (meth)acrylate resin, was obtained. The compound (A-3) having a polar group had a mass average molecular weight (Mw) of 4,663 and an acid value of 27.3 mgKOH/g.

(Production Example 4) Production of a compound (A-4) having a polar group A flask equipped with a stirrer, a gas inlet tube, a condenser and a thermometer was charged with 201.4 parts by mass of lactone-modified hydroxyethyl acrylate (Daicel Corporation's "Placcel FA2D"), 3.8 parts by mass of glycolic acid, and 0.17 parts by mass of N-nitroso-N-phenylhydroxylamine aluminum, and heated to 65°C. 116.7 parts by mass of isocyanurate-modified hexamethylene diisocyanate (Sumidur N3300 manufactured by Sumika Covestro Urethane Co., Ltd.) was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was heated to 95°C and reacted for 2 hours. It was confirmed that the infrared absorption spectrum at 2250 cm ^-1 indicating an isocyanate group had disappeared, and a compound (A-4) having a polar group, which is a urethane (meth)acrylate resin, was obtained. The compound (A-4) having a polar group had a mass average molecular weight (Mw) of 4,135 and an acid value of 8.9 mgKOH/g.

(Production Example 5) Production of a compound (A-5) having a polar group A flask equipped with a stirrer, a gas inlet tube, a condenser and a thermometer was charged with 167.9 parts by mass of lactone-modified hydroxyethyl acrylate (Daicel Corporation's "Placcel FA2D"), 3.4 parts by mass of dimethylolpropionic acid, and 0.17 parts by mass of N-nitroso-N-phenylhydroxylamine aluminum, and heated to 65°C. 116.9 parts by mass of isocyanurate-modified hexamethylene diisocyanate (Sumidur N3300 manufactured by Sumika Covestro Urethane Co., Ltd.) was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was heated to 95°C and reacted for 2 hours. It was confirmed that the infrared absorption spectrum at 2250 cm ^-1 indicating an isocyanate group had disappeared, and a compound (A-5) having a polar group, which is a urethane (meth)acrylate resin, was obtained. The compound (A-5) having a polar group had a mass average molecular weight (Mw) of 4,389 and an acid value of 5.5 mgKOH/g.

(Production of Compositions (1) to (8) of Compound Having a Polar Group and Metal Complex)
Compounds (A-1) to (A-5) having a polar group, a (meth)acrylate monomer, and a metal complex were mixed in the ratios shown in Table 1, and stirred for 1 hour to obtain compositions (1) to (8). The numbers in Table 1 indicate the number of parts, and the abbreviations in Table 1 are as follows:
(Meth)acrylate monomer: "OTA 480" manufactured by Daicel Allnex Corporation, propylene oxide modified glycerin triacrylate, average number of propylene oxide units added per molecule: 3
Metal complex (B-1): "ALCH-TR" manufactured by Kawaken Fine Chemical Co., Ltd., aluminum tris(ethylacetoacetate)
Metal complex (B-2): "Plenact AL-M" manufactured by Ajinomoto Fine-Techno Co., Ltd., aluminum alkyl acetoacetate diisopropylate

(Production Example 6) Production of urethane (meth)acrylate resin 60.3 parts by mass of polymeric diphenylmethane diisocyanate ("Millionate MR-400" manufactured by Nippon Polyurethane Industry Co., Ltd.), 0.1 parts by mass of tertiary butyl hydroxytoluene, 0.02 parts by mass of methoxyhydroquinone, and 0.02 parts by mass of zinc octylate were added to a four-neck flask equipped with a stirring blade, a gas inlet tube, a condenser, and a thermometer, and the mixture was heated to 75°C. 35.7 parts by mass of 2-hydroxyethyl acrylate was added dropwise over 1 hour while stirring the contents of the flask. After the dropwise addition was completed, the reaction was continued at 75°C, and it was confirmed that the infrared absorption spectrum at 2250 cm ^-1 indicating an isocyanate group had disappeared, and a urethane (meth)acrylate resin was obtained.

(Examples and Comparative Examples) Production of Printing Ink (Preliminary Dispersion)
The ink raw materials other than the compositions (1) to (8) and the metal complex were mixed in a vessel having a diameter of 65 (D) mm in a predetermined ratio, and stirred for 5 minutes at 16,000 rpm (circumferential speed 25 m/s) using a vertical dissolver (VMA Dispermat LC30 (d/D = 0.46)) with a stirring blade having a diameter of 30 (d) mm. Thereafter, the compositions (1) to (8) and the metal complex were added to the stirred printing ink raw materials, and then stirred again for 10 minutes at 16,000 rpm (circumferential speed 25 m/s). After stirring, the temperature of the obtained dispersion was measured and confirmed to be in the range of 50°C to 70°C.

(Book dispersion)
The dispersion obtained in the above preliminary dispersion step was milled using a three-roll mill to obtain an active energy ray-curable ink for lithographic offset printing.

Details of the ink ingredients are as shown in Table 1.

(Performance evaluation test)
<Static fluidity>
1.3 g of the active energy ray curable ink for lithographic offset printing obtained in the Examples and Comparative Examples was dropped onto a brass inclined plate tilted at 60° in an atmosphere of 25° C., and the distance the ink flowed from the landing point in 10 minutes was measured and evaluated as static fluidity. The evaluation criteria are as follows:
5: 86mm or more
4: 61-85mm
3: 46-60mm
2: 21-45mm
1: 20mm or less

<Continuous printing>
For the active energy ray curable inks for lithographic offset printing obtained in the Examples and Comparative Examples, a continuous printing test was carried out using the following printing machine, sampling was carried out every 3000 sheets, 8000 sheets, 12000 sheets, and 16000 sheets, and the continuous printability was evaluated by visually observing the presence or absence of stains on the printed matter. The evaluation criteria are as follows.
5: Good prints were obtained at the 16,000th sheet point.
4: Good prints were obtained at 12,000 sheets, but not at 16,000 sheets.
3: Good prints were obtained at 8,000 sheets, but not at 12,000 sheets.
2: Good prints were obtained at 3,000 sheets, but not at 8,000 sheets.
1: No good prints were obtained at the 3000th sheet point.

(Printing conditions)
・Offset printing machine: LITHRONEG40 (manufactured by Komori Corporation)
・PS version: XP-F (manufactured by FujiFile Global Graphics Systems)
・Paper: OK Topcoat Plus (Oji Paper)
Dampening water: Tap water/Astromark 3 (manufactured by Nikken Chemical Laboratory Co., Ltd.)/isopropyl alcohol mixed in a composition of 95% by mass/2% by mass/3% by mass. Printing conditions: Room temperature 25±1°C, printing speed 8000 sheets/hour. Printing operation conditions: The dampening water supply device was set to the lowest possible level without causing smudges on the printed matter.

<Storage stability>
The active energy ray curable inks for lithographic offset printing obtained in the Examples and Comparative Examples were left at 60° C., and the ink state after 2 weeks and 4 weeks was observed visually and by palpation with a metal spatula to evaluate storage stability. The evaluation criteria are as follows:
◯: After 4 weeks, the ink was normal. Good Δ: After 2 weeks, the ink was normal, but after 4 weeks, the ink gelled. Practical range ×: After 2 weeks, the ink gelled. Not practical.

The results are shown in Tables 2 to 7. Blank spaces in the tables indicate no blend.

In the table, the abbreviations are as follows:
Polar group (--COOH) mmol/g: carboxyl group, which is a polar group, mmol/g in compositions (1) to (8), which are mixtures of a metal complex and a compound having a polar group.
mmol/g of metal complex: mmol/g of metal complex in compositions (1) to (8) which are mixtures of a metal complex and a compound having a polar group.
Pigment Red 57:1: DIC SYMULER BRILLIANT CARMINE 6B 426SD
Pigment Yellow 13: DIC SYMULER FAST YELLOW 4340
Pigment Black 7: BIRLA CARBON Carbon Laben 1060 Powder Pigment Blue 15:3: DIC FASTOGEN BLUE FA5375
Dipentaerythritol hexaacrylate: Toagosei Co., Ltd. Aronix M-400
Ditrimethylolpropane tetraacrylate: Toagosei Co., Ltd. Aronix M-408
Ethylene oxide modified trimethylolpropane triacrylate: Miramer M3130 manufactured by MIWON
Q-1301: 5 parts by mass of "Q1301" manufactured by Wako Pure Chemical Industries, Ltd. and 5 parts by mass of MIRAMER M31309 were mixed by stirring.

Claims (5)

A method for producing an active energy ray-curable ink for lithographic offset printing, which contains a monomer having an ethylenically unsaturated double bond, a metal complex, an acid group-containing urethane (meth)acrylate resin, a pigment, and a polar group-containing pigment dispersant, the method being characterized in that the metal complex and the acid group-containing urethane (meth)acrylate resin are mixed and dispersed in advance, and then the monomer having an ethylenically unsaturated double bond, the pigment, and the polar group-containing pigment dispersant are mixed and dispersed. The method for producing an active energy ray-curable ink for lithographic offset printing according to claim 1, wherein the central metal of the metal complex is aluminum, titanium, or zirconium. The method for producing an active energy ray-curable ink for lithographic offset printing according to claim 1 or 2, wherein the polar group-containing pigment dispersant is a basic group-containing pigment dispersant having an acid value. A method for producing a cured ink product, comprising offset printing using the active energy ray-curable ink for lithographic offset printing according to any one of claims 1 to 3, and curing the printed ink using active energy rays. A method for producing a printed matter obtained by the method for producing an ink cured product according to claim 4.