JP7464476B2 - Active energy ray curable ink for lithographic offset printing and printed matter - Google Patents

Description

The present invention relates to an active energy ray-curable ink for lithographic offset printing, the substrate of which is a film substrate or paper. It also relates to a printed matter using the ink.

Active energy ray curable inks are solvent-free and instantly cure and dry using active energy rays, making them environmentally friendly, easy to print, and capable of producing high-quality prints. They are used in a variety of printing methods that combine lithographic printing (lithographic printing using dampening water and waterless lithographic printing not using dampening water), letterpress printing, intaglio printing, stencil printing, and transfer (offset) printing, which involves transferring the ink on these plates to an intermediate transfer medium such as a blanket and then printing on the print medium. They are used in a variety of prints, including prints for forms, various book prints, various packaging prints such as carton paper, various plastic prints, seals, prints for labels, fine art prints, and metal prints (fine art prints, prints on beverage cans, prints on canned food, etc.). Of these, lithographic offset printing active energy ray curable inks, in which the ink on a lithographic printing plate is transferred to an intermediate transfer medium such as a blanket and then printed on the print medium, are widely used as a high-speed printing method for printing on paper, plastic substrates, and soft packaging substrates used in the food packaging field.

Conventionally, diallyl phthalate resin, urethane resin, polyester resin, etc. have been generally used as binder resins for active energy ray curable inks for lithographic offset printing (for example, see Patent Document 1). Among them, diallyl phthalate resin is characterized by having both high elasticity and fluidity, and other binder resins having the same high elasticity and fluidity as diallyl phthalate resin have not been found. On the other hand, diallyl phthalate resin contains unreacted diallyl phthalate monomer (diallyl phthalate, CAS number 131-17-9) that remains in the resin and is a former Type II monitored chemical substance and a substance of high concern for mutagenicity (GHS Class 1B (germ cell mutagenicity)), so there is an increasing demand for diallyl phthalate-free resins for use in active energy ray curable inks for lithographic offset printing (for example, see paragraph 0009 of Patent Document 3).
On the other hand, in recent years, as the demand for environmentally friendly products aimed at combating global warming and reducing the environmental impact has been increasing, when using plant-derived raw materials, it is desirable to design products that take into account the compatibility of the binder resins and monomers used with the plant-derived raw materials.

JP 2015-193677 A JP 2015-174994 A WO14/129461

The object of the present invention is to provide an active energy ray-curable ink for lithographic offset printing that uses plant-derived raw materials and has excellent ink fluidity, compatibility, and viscoelasticity, even without using diallyl phthalate resin, which is equal to or better than the ink that uses diallyl phthalate resin.

As a result of extensive research conducted by the inventors to solve the above problems, the above problems were solved by incorporating a specific acrylic copolymer (A), a (meth)acrylate compound (B), a vegetable oil-modified (meth)acrylate compound (B2), an extender pigment (D), and a polar group-containing pigment dispersant (E).

That is, the present invention relates to a composition comprising: (a) 5 to 70% by mass of a polyfunctional (meth)acrylate compound having 2 to 6 functional groups;
(b) 0.1 to 50% by mass of an aryl (meth)acrylate compound, (c) 5 to 40% by mass of a styrene compound, (d) 0.1 to 10% by mass of a polymerizable unsaturated bond-containing compound having a hydrophilic group, and (e) 0.1 to 10% by mass of a (meth)acrylate compound having a nitrogen-containing heterocyclic group,
(f) a copolymer (A) made of a polymer containing, as an essential polymerization component, 0.1 to 10% by mass of a (meth)acrylate compound having an alkylamino group (the total amount of (a) to (f) is 100% by mass);
A (meth)acrylate compound (B),
A vegetable oil-modified (meth)acrylate compound (B2),
An extender pigment (D),
and a polar group-containing pigment dispersant (E).

The present invention also relates to an active energy ray-curable ink for lithographic offset printing, in which the copolymer (A) has a weight average molecular weight of 5,000 to 100,000, a PDI of the molecular weight of 3 to 35, and an acid value of 1 to 40 mg/KOH/g.

The present invention also relates to an active energy ray-curable ink for lithographic offset printing, in which the mass ratio of the copolymer (A) to the (meth)acrylate compound (B) is in the range of 5:65 to 30:40.

The present invention also relates to an actinic radiation-curable ink for lithographic offset printing, which contains at least one extender pigment (D) selected from the group consisting of talc, magnesium carbonate, and calcium carbonate.

The present invention also relates to an actinic radiation-curable ink for lithographic offset printing, in which the polar group-containing pigment dispersant (E) is a basic group-containing pigment dispersant having an acid value.

The present invention also relates to a method for producing a cured ink product, which comprises offset printing using the 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 having a cured product of the above-described active energy ray-curable ink for lithographic offset printing on a substrate.

According to the present invention, it is possible to provide an active energy ray-curable ink for lithographic offset printing which uses plant-derived raw materials and has excellent ink fluidity, compatibility, and viscoelasticity similar to those obtained when a diallyl phthalate resin is used, even without using a diallyl phthalate resin.
The active energy ray curable ink for lithographic offset printing of the present invention can be suitably used as an ink for lithographic offset printing which uses fountain solution.

(Definition of words)
In the present invention, the term "(meth)acrylate" refers to either or both of an acrylate and a methacrylate, and the term "(meth)acryloyl group" refers to either or both of an acryloyl group and a methacryloyl group.

(Copolymer (A))
The copolymer (A) used in the present invention is
(a) 5 to 70% by mass of a polyfunctional (meth)acrylate compound having 2 to 6 functional groups;
(b) 0.1 to 40% by mass of an aryl (meth)acrylate compound, (c) 5 to 40% by mass of a styrene compound, (d) 0.1 to 10% by mass of a polymerizable unsaturated bond-containing compound having a hydrophilic group, and (e) 0.1 to 10% by mass of a (meth)acrylate compound having a nitrogen-containing heterocyclic group,
(f) A polymer containing, as an essential polymerization component, 0.1 to 10% by mass of a (meth)acrylate compound having an alkylamino group (the total amount of (a) to (f) is 100% by mass).

Examples of the polyfunctional (meth)acrylate compound having 2 to 6 functional groups, which is an essential polymerization component of the copolymer (A), include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, 1,3 butylene glycol di(meth)acrylate, 1,6 hexanediol di(meth)acrylate, 1,9 nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, allyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolethane tri(meth)acrylate, and ethylene oxide modified trimethylolpropane tri(meth)acrylate pentaacrylate. Examples of the acrylates include taerythritol tetra(meth)acrylate, sorbitol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dimethylolethane tetra(meth)acrylate, dimethylolbutane tetra(meth)acrylate, dimethylolhexane tetra(meth)acrylate, dimethyloloctane tetra(meth)acrylate, diglycerin tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol propionate tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, sorbitol penta(meth)acrylate, dipentaerythritol (meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, and sorbitol hexa(meth)acrylate. One of these may be used alone, or two or more may be used in combination.

(b) Aryl (meth)acrylate compounds, which are essential polymerization components of the copolymer (A), include, for example, benzyl (meth)acrylate, phenoxy (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phonoxypolyethylene glycol (meth)acrylate, phenyl (meth)acrylate, ethoxylated o-phenylphenol (meth)acrylate, etc. One of these may be used alone, or two or more may be used in combination.

Examples of the styrene compound (c), which is an essential polymerization component of the copolymer (A), include alkyl styrenes such as styrene, α-methylstyrene, β-methylstyrene, 2,4-dimethylstyrene, α-ethylstyrene, α-butylstyrene, and α-hexylstyrene, halogenated styrenes such as 4-chlorostyrene, 3-chlorostyrene, and 3-bromostyrene, 3-nitrostyrene, and 4-methoxystyrene. Only one of these may be used alone, or two or more may be used in combination.

Examples of the (d) polymerizable unsaturated bond-containing compound having a hydrophilic group, which is an essential polymerization component of the copolymer (A), include acrylic acid, methacrylic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate (n, which indicates the degree of polymerization of polyethylene glycol, is 3 to 23). Only one of these may be used alone, or two or more may be used in combination.

(e) (meth)acrylates having a nitrogen-containing heterocyclic group, which are essential polymerization components of the copolymer (A), include, for example, acryloylmorpholine, 3-acryloyl-2-oxazolidinone, etc. One of these may be used alone, or two or more may be used in combination.

(f) (meth)acrylate having an alkylamino group, which is an essential polymerization component of the copolymer (A), includes, for example, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. One of these may be used alone, or two or more may be used in combination.

The copolymer (A) used in the present invention has a weight average molecular weight of 5,000 to 100,000. Of these, the range of 10,000 to 80,000 is preferred, and the range of 20,000 to 70,000 is more preferred. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) method, and is a value converted into the molecular weight of polystyrene used as a standard substance.

The copolymer (A) used in the present invention has a molecular weight PDI of 3 to 35. Of these, a range of 5 to 30 is preferred, and a range of 8 to 25 is more preferred. The molecular weight PDI is an abbreviation for poly dispersity index (PDI), which is a value obtained by dividing the weight average molecular weight measured by the GPC method by the number average molecular weight also measured by the GPC method.

The copolymer (A) used in the present invention preferably has an acid value in the range of 1 to 40 mg/KOH/g.
The acid value is a value measured by the neutralization titration method described in the Japanese Industrial Standards "K0070:1992, Testing methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products".

In the copolymer (A), the ratio of each of the compounds (a) to (f) is as follows:
(a) 5 to 70% by mass of a polyfunctional (meth)acrylate compound having 2 to 6 functional groups;
(b) 0.1 to 40% by mass of an aryl (meth)acrylate compound, (c) 5 to 50% by mass of a styrene compound, (d) 0.1 to 10% by mass of a polymerizable unsaturated bond-containing compound having a hydrophilic group, and (e) 0.1 to 10% by mass of a (meth)acrylate compound having a nitrogen-containing heterocyclic group,
(f) 0.1 to 10% by mass of a (meth)acrylate compound having an alkylamino group
The components (a) to (f) are mixed in a range satisfying the above formula (1) and polymerized by a known method to obtain a polymerized product. However, the total amount of the components (a) to (f) is 100% by mass.
In the above ratio, more preferably,
(a) 10 to 70% by mass of a polyfunctional (meth)acrylate compound having 2 to 6 functional groups;
(b) 5 to 35 mass% of an aryl (meth)acrylate compound, (c) 10 to 45 mass% of a styrene compound, (d) 0.5 to 8 mass% of a polymerizable unsaturated bond-containing compound having a hydrophilic group, and (e) 1 to 8 mass% of a (meth)acrylate compound having a nitrogen-containing heterocyclic group,
(f) 0.5 to 8% by mass of a (meth)acrylate compound having an alkylamino group
(However, the total amount of (a) to (f) is mixed so that it becomes 100 mass %)
and more preferably,
(a) 20 to 70% by mass of a polyfunctional (meth)acrylate compound having 2 to 6 functional groups;
(b) 10 to 30 mass% of an aryl (meth)acrylate compound, (c) 15 to 40 mass% of a styrene compound, (d) 1 to 7 mass% of a polymerizable unsaturated bond-containing compound having a hydrophilic group, and (e) 2 to 6 mass% of a (meth)acrylate compound having a nitrogen-containing heterocyclic group,
(f) 0.5 to 6 mass% of a (meth)acrylate compound having an alkylamino group
(However, the total amount of (a) to (f) is mixed so that it becomes 100 mass %)
It is.

The copolymer (A) can be obtained by a known polymerization method, such as a solution polymerization method.

Examples of the solvent include aromatic hydrocarbon solvents, ketone solvents, ether solvents, and ester solvents. Only one of these may be used alone, or two or more may be used in combination. For example, it is preferable to use 50 to 500 parts by mass of the solvent per 100 parts by mass, which is the total amount of the polymerization components of the copolymer (A).

When polymerizing the polymerization components, for example, a radical polymerization initiator can be used. The radical polymerization initiator is not particularly limited, and for example, an inorganic peroxide, an organic peroxide, an azo compound, etc. can be used.

Specific examples of radical polymerization initiators include inorganic peroxides such as ammonium persulfate and potassium persulfate, benzoyl peroxide, t-butyl peroxyacetate, 2,2-di-(t-butylperoxy)butane, t-butyl peroxybenzoate, n-butyl 4,4-di-(t-butylperoxyisopropyl)benzene, dicumyl peroxide, di-t-hexyl peroxide, 2,5-dimethyl-2,5,-di(t-butylperoxy)hexane, t-butylcumyl peroxide, and di-t-butyl peroxy. Examples of the initiator include organic peroxides such as diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and t-butyltrimethylsilyl peroxide, and azo compounds such as 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile). One of these may be used alone, or two or more may be used in combination. It is preferable to use 0.1 to 20 parts by mass of these radical polymerization initiators relative to 100 parts by mass, which is the total amount of the polymerization components.

When polymerizing the polymerization components, for example, a chain transfer agent can be used. The chain transfer agent is not particularly limited, and examples thereof include lauryl mercaptan, dodecyl mercaptan, 2-mercaptobenzothiazole, bromotrichloromethane, etc. Only one of these may be used alone, or two or more may be used in combination. It is preferable to use 0.01 to 5 parts by mass of these chain transfer agents per 100 parts by mass, which is the total amount of the polymerization components.

The amount of copolymer (A) used in the present invention is preferably in the range of 5 to 30% by mass, more preferably 15 to 25% by mass, based on the total amount of the active energy ray-curable ink.

((Meth)acrylate Compound (B))
The (meth)acrylate compound (B) used in the present invention may be any (meth)acrylate commonly used in active energy ray-curable ink technology. Specific examples of such compounds include monofunctional (meth)acrylates and polyfunctional (meth)acrylates.
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, and the like.

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 glycol di(meth)acrylates of dihydric alcohols such as 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; di(meth)acrylates of diols obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol; ) acrylate, di(meth)acrylate of a diol obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A, poly(meth)acrylate of a polyhydric alcohol having three or more valences, such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and poly(meth)acrylate of dipentaerythritol, poly(meth)acrylate of 3 or more moles of ethylene oxide or Examples of the polyoxyalkylene polyol include poly(meth)acrylates of polyoxyalkylene polyols such as tri(meth)acrylates of triols obtained by adding propylene oxide, di- or tri(meth)acrylates of triols obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane (trimethylolpropane ethylene oxide modified tri(meth)acrylate), and di(meth)acrylates of diols obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of bisphenol A. These may be used alone or in combination of two or more.

Among them, it is preferable that the (meth)acrylate compound (B) contains a bifunctional or higher (meth)acrylate, and it is even more preferable that the (meth)acrylate compound (B) contains a trifunctional or higher (meth)acrylate. In particular, the trifunctional or higher (meth)acrylate is preferably at least one selected from the group consisting of dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and trimethylolpropane ethylene oxide modified tri(meth)acrylate.

The (meth)acrylate compound (B) is preferably used in an amount ranging from 20 to 70% by mass, more preferably from 30 to 60% by mass, based on the total amount of the active energy ray-curable ink.

The copolymer (A) and the (meth)acrylate compound (B) are preferably mixed in a ratio ranging from 5:65 to 30:40, and more preferably from 15:55 to 25:45.

(Vegetable Oil Modified (Meth)Acrylate Compound (B2))
In the present invention, it is preferable that the (meth)acrylate compound (B) contains a vegetable oil-modified (meth)acrylate compound (B2). By using the vegetable oil-modified (meth)acrylate compound (B2) using a raw material derived from a plant, for example, an effect of increasing a biomass-derived component is brought about.
Incidentally, since the vegetable oil-modified (meth)acrylate compound (B2) is in the category of the (meth)acrylate compound (B), when the vegetable oil-modified (meth)acrylate compound (B2) is used in combination with a (meth)acrylate compound (B) other than the vegetable oil-modified (meth)acrylate compound (B2), the "(meth)acrylate compound (B) other than the vegetable oil-modified (meth)acrylate compound (B2)" may be referred to as the "(meth)acrylate compound (B1)."

Among the vegetable oil-modified (meth)acrylate compounds (B2), epoxidized vegetable oil-modified acrylates are preferred.

Examples of epoxidized vegetable oils that are reaction raw materials for the epoxidized vegetable oil modified acrylate include epoxidized soybean oil, epoxidized linseed oil, epoxidized tung oil, epoxidized castor oil, epoxidized palm oil, epoxidized cottonseed oil, epoxidized camellia oil, epoxidized olive oil, epoxidized corn oil, epoxidized coconut oil, and epoxidized safflower oil, etc. These can be used alone or in combination of two or more kinds.
Among these epoxidized vegetable oils, those selected from epoxidized soybean oil, epoxidized linseed oil, epoxidized tung oil and epoxidized castor oil are particularly preferred, with epoxidized soybean oil being particularly preferred.
Specific examples of the epoxidized soybean oil include PHOTOMER 3005 (CAS. No. 91722-14-4, manufactured by IGM Resins B.V.), EB860, EB5848 (manufactured by Daicel Allnex Co., Ltd.), MIRAMER PE310 (manufactured by MIWON), LAROMER EA9101 (manufactured by BASF), CN111 (manufactured by SARTOMER), and Agysin 2020 (manufactured by DSM). These may be used alone or in appropriate combination of two or more.

By combining the epoxidized soybean oil-modified acrylate, which has excellent flexibility, with a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (DPHA), ditrimethylolpropane tetraacrylate (DTMPTA), trimethylolpropane ethylene oxide-modified triacrylate, or the like, which have poor flexibility, in an appropriate amount range, it is possible to achieve a balance between the film strength and flexibility of the ink coating and to maintain the fluidity and viscoelasticity of the ink.
That is, the ratio of the vegetable oil-modified (meth)acrylate compound (B2) and the (meth)acrylate compound (B1) which is the (meth)acrylate compound (B) other than the vegetable oil-modified (meth)acrylate compound (B2) is used in combination,
The ratio of the vegetable oil-modified (meth)acrylate compound (B2):(meth)acrylate compound (B1) is preferably in the range of 5:45 to 30:19, more preferably in the range of 7:43 to 20:30, and most preferably in the range of 12:37.5 to 18:31.5.

(Extender Pigment (D))
In the active energy ray curable ink for lithographic offset printing of the present invention, it is preferable to use a body pigment. Inorganic fine particles can be used as the body pigment. Examples of inorganic fine particles include inorganic coloring pigments such as titanium oxide, graphite, and zinc oxide; inorganic body pigments such as lime carbonate powder, precipitated calcium carbonate, precipitated barium sulfate, gypsum, clay (China Clay), silica, diatomaceous earth, talc, kaolin, alumina white, barium sulfate, aluminum stearate, calcium stearate, magnesium carbonate, barite powder, and grinding powder; and inorganic pigments such as silicone and glass beads. These inorganic fine particles can adjust the flowability of the ink, prevent misting, and prevent penetration into printing substrates such as paper, and can also add an effect of suppressing the trouble of paper peeling that occurs during printing under low temperature conditions such as winter or high-speed printing.

Among these, talc, magnesium carbonate, and calcium carbonate are preferred from the viewpoint of preventing paper peeling, and talc and magnesium carbonate are particularly preferred from the viewpoint of maintaining the fluidity of the ink.

The talc, magnesium carbonate, and calcium carbonate may be used alone or in combination of two or more. When the talc is used, its content is preferably in the range of 1 to 6 mass% of the total ink composition, and when magnesium carbonate and calcium carbonate are used, their content is preferably in the range of 1 to 10 mass% of the total ink composition.

(Polar Group-Containing Pigment Dispersant (E))
The pigment dispersant used in the present invention is preferably a polar group-containing pigment dispersant (E) because it can further improve the dispersibility of the pigment and the fluidity of the ink. 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 the present invention, the basic group-containing pigment dispersant may be a commercially available dispersant known as a basic dispersant. 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.).

(Other binder resins)
In the present invention, it is essential to use the copolymer (A), but other known and publicly used various binder resins can be used in combination. The binder resin described here refers to any resin having appropriate pigment affinity and dispersibility and rheological properties required for printing inks. For example, non-reactive resins include diallyl phthalate resins, epoxy resins, epoxy ester resins, polyurethane resins, polyester resins, petroleum resins, rosin ester resins, poly(meth)acrylic acid esters (excluding the acrylic copolymer (A) containing a styrene monomer and benzyl (meth)acrylate as essential polymerization components), cellulose derivatives, vinyl chloride-vinyl acetate copolymers, polyamide resins, polyvinyl acetal resins, butadiene-acrylonitrile copolymers, etc., and epoxy acrylate compounds, urethane acrylate compounds, polyester acrylate compounds, etc. having at least one polymerizable group in the molecule can 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.).

(Photopolymerization initiator)
Next, in consideration of the curing properties of the ink, the active energy ray-curable ink for lithographic offset printing of the present invention preferably further contains a photopolymerization initiator.
When a photopolymerization initiator is used, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, thioxanthone and thioxanthone derivatives, 2,2'-dimethoxy-1,2-diphenylethan-1-one, diphenyl(2,4,6-trimethoxybenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, etc. can be mentioned. These photopolymerization initiators can be used alone or in combination of two or more kinds.

Commercially available products of the photopolymerization initiator include, for example, "Omnirad-1173", "Omnirad-184", "Omnirad-127", "Omnirad-2959", "Omnirad-369", "Omnirad-379", "Omnirad-907", "Omnirad-4265", "Omnirad-1000", "Omnirad-651", "Omnirad-TPO", "Omnirad-819", "Omnirad-2022", "Omnirad-2100", "Omnirad-754", "Omnirad-784", "Omnirad-50 ...4265", "Omnirad-1000", "Omnirad-4265", "Omnirad-1000", "Omnirad-4265", "Omnirad-4265", "Omnirad-1000", "Omnirad-4265", " Examples include "irad-81" (manufactured by IGM), "Kayacure-DETX", "Kayacure-MBP", "Kayacure-DMBI", "Kayacure-EPA", "Kayacure-OA" (manufactured by Nippon Kayaku Co., Ltd.), "Bi-Cure-10", "Bi-Cure-55" (manufactured by Stouffer Chemical Co., Ltd.), "Trigonal P1" (manufactured by Akzo), "Sandray 1000" (manufactured by Sandoz Co., Ltd.), "Deep" (manufactured by Upjohn), "Quantacure-PDO", "Quantacure-ITX", "Quantacure-EPD" (manufactured by Ward Blenkinsop Co., Ltd.), and "Runtecure-1104" (manufactured by Runtec).

When the photopolymerization initiator is contained, its amount is preferably in the range of 1 to 20 mass % in terms of solid content in the active energy ray curable ink for lithographic offset printing of the present invention, and more preferably in the range of 5 to 15 mass %. In other words, when the total amount of photopolymerization initiator used is 1 mass % or more, good curability can be obtained, and when it is 20 mass % or less, no unreacted polymerization initiator remains in the cured product, and curing defects can be suppressed. However, when electron beams are used as the active energy rays, the use of these photopolymerization initiators is not essential in principle.

In addition, since the active energy ray-curable ink for lithographic offset printing can improve the curability of the cured coating film of the active energy ray-curable resin composition, a photosensitizer can be further added to improve the curability, if necessary.

Examples of the photosensitizer include amine compounds such as aliphatic amines and aromatic amines, urea compounds such as o-tolylthiourea, and sulfur compounds such as sodium diethyldithiophosphate and s-benzylisothiuronium-p-toluenesulfonate. The amount of these photosensitizers used is preferably in the range of 1 to 20% by mass, including the alkylaminobenzophenone compound, based on 100% by mass of non-volatile components in the active energy ray-curable ink of the present invention, in order to achieve a good effect in improving curability.

(Pigment)
The active energy ray curable ink for lithographic offset printing of the present invention functions as a printing ink that imparts visibility by containing a pigment as a coloring material. When the ink does not contain a pigment, it can also be used as an overprint varnish (OP varnish) used for the purpose of overcoating a printed layer. Examples of pigments used as coloring materials include well-known and commonly used inorganic pigments and organic pigments.

Examples of the inorganic pigment include iron oxide and carbon black produced by known methods such as the contact method, furnace method, and thermal method.
Examples of such compounds include Raben 14, Raben 450, Raben 860 Ultra, Raben 1035, Raben 1040, Raben 1060 Ultra, Raben 1080 Ultra, Raben 1180, Raben 1255 (all manufactured by Birla), Regal 250R, Regal 400R, Regal 330R, Regal 660R, Mogul L (all manufactured by Cabot Corporation), MA7, MA8, MA11 (all manufactured by Mitsubishi Chemical Corporation), and the like. These compounds may be used alone or in appropriate combination of two or more.

Examples of the organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, azo pigments, etc. These pigments can be used alone or in combination of two or more.

Specific examples of pigments used in yellow inks include C.I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, and 185.

Specific examples of pigments used in magenta inks include C.I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122, 123, 146, 168, 176, 184, 185, 202, 209, 269, etc., and C.I. Pigment Violet 19, etc.

Specific examples of pigments used in cyan inks include C.I. Pigment Blue 1, 2, 3, 15, 15:3, 15:4, 16, 22, 60, 63, and 66.

(Other additives)
The active energy ray curable ink for lithographic offset printing of the present invention may further contain other additives, such as antioxidants, polymerization inhibitors, silicon-based additives, waxes, dyes, etc., as required.

Examples of the antioxidant include hindered phenol-based antioxidants, hindered amine-based antioxidants, organic sulfur-based antioxidants, and phosphate-based antioxidants. These antioxidants can be used alone or in combination of two or more.

Examples of the silicon-based additives include polyorganosiloxanes having alkyl or phenyl groups, such as dimethylpolysiloxane, methylphenylpolysiloxane, cyclic dimethylpolysiloxane, methylhydrogenpolysiloxane, polyether-modified dimethylpolysiloxane copolymer, polyester-modified dimethylpolysiloxane copolymer, fluorine-modified dimethylpolysiloxane copolymer, and amino-modified dimethylpolysiloxane copolymer, polydimethylsiloxane having polyether-modified acrylic groups, and polydimethylsiloxane having polyester-modified acrylic groups. These silicon-based additives can be used alone or in combination of two or more kinds.

In the actinic energy ray-curable ink for lithographic offset printing of the present invention, wax can be added for the purpose of improving curability. Examples of the wax include waxes such as paraffin wax, carnauba wax, beeswax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, polytetrafluoroethylene wax, and amide wax, and fatty acids having an atomic carbon number of about 8 to 18, such as coconut oil fatty acid and soybean oil fatty acid.
The active energy ray-curable ink for lithographic offset printing of the present invention can be printed on a substrate and then irradiated with active energy rays to form a cured coating film.

Examples of the active energy rays include ionizing radiation such as ultraviolet rays, electron beams, α rays, β rays, and γ rays. When ultraviolet rays are used as the active energy rays, irradiation may be performed in an inert gas atmosphere such as nitrogen gas, or in an air atmosphere, in order to efficiently carry out the curing reaction by ultraviolet rays.

As a source of the ultraviolet rays, ultraviolet lamps are generally used from the viewpoints of practicality and economy. Specific examples include germicidal lamps, ultraviolet fluorescent lamps, high-pressure mercury lamps for copying, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, extra-high-pressure mercury lamps, electrodeless lamps, carbon arcs, xenon lamps, gallium lamps, metal halide lamps, sunlight, ultraviolet light-emitting diodes (UV-LEDs), etc.

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.

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

(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 perspective, in the actinic radiation curable ink for lithographic offset printing of the present invention, the acid value of the resin or monomer used in the ink is preferably within the range of 0 to 20.0, and more preferably within the range of 0.0 to 10.0. If the acid value of the resin or monomer is high, the ink is more likely to emulsify, and when 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 hydrophilically treated non-image areas on the plate, causing stains on the non-image areas of the printed matter.

The present invention will be specifically explained below with examples and comparative examples.

Example 1
(Method of manufacturing active energy ray curable ink for lithographic offset printing)
Copolymer (A) was prepared by mixing 18 parts by mass of copolymer (A-1), which is a polymer of the polymerization components shown in Table 1, 15 parts by mass of Photomer 3005F (CAS. No. 91722-14-4), which is a vegetable oil-modified (meth)acrylate, and 34.5 parts by mass of dipentaerythritol hexaacrylate, and the inside of a reaction vessel was heated to 110° C. to prepare varnish (V1).
Further, 10 parts by mass of an acylphosphine oxide-based photopolymerization initiator Omnirad TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by IGM) and 5 parts by mass of Omnirad EMK (4,4'-bisdiethylaminobenzophenone, manufactured by IGM) were mixed with the varnish (V1) as a photopolymerization initiator at 60°C for 3 hours, and then 15 parts by mass of carbon black Raven 1060 Ultra (manufactured by BIRLA CARBON), 2 parts by mass of extender pigment High Filler #5000PJ, and 0.5 parts by mass of a polar group-containing pigment dispersant Solsperse 24000 were added thereto to make a total of 100 parts by mass. The mixture was then stirred using a mixer (single-shaft dissolver), and the blend was milled using a three-roll mill to obtain active energy ray-curable offset black ink 1.

The values in Table 1 are the number of parts (solid content) and blank spaces indicate that the material is not blended. The abbreviations are as follows:
Polymerization component (a): a polyfunctional (meth)acrylate compound having two or three functional groups; Polymerization component (b): an aryl (meth)acrylate compound; Polymerization component (c): a styrene compound and polymerization component (d): a polymerizable unsaturated bond-containing compound having a hydrophilic group; Polymerization component (e): a (meth)acrylate compound having a nitrogen-containing heterocyclic group; Polymerization component (f): a (meth)acrylate compound having an alkylamino group.

[Examples 2 to 12 and Comparative Examples 1 to 8: Preparation of active energy ray curable offset black inks 2 to 20]
For Examples 2 to 12 and Comparative Examples 1 to 8, Black Ink 2 to Ink 20 were prepared in the same manner as in Example 1 according to the formulations shown in Tables 2 to 5.
In Examples 2 to 8, 10, and 12 and Comparative Examples 5 and 6, the copolymer (A-2) shown in Table 1 was used instead of the copolymer (A-1).

The active energy ray curable offset black inks obtained in the above Examples and Comparative Examples were used to carry out the following evaluations.
It was confirmed that the ink viscosities of the obtained black inks 1 to 20 at 25° C. were 25 Pa.s.

The resulting active energy ray-curable offset black ink was used to evaluate paper peeling on a printing press.

[Evaluation item 1: Compatibility]
Each of the active energy ray curable offset black inks 1 to 20 was prepared by mixing the copolymer (A-1) or (A-2) in the process of being produced, the vegetable oil modified (meth)acrylate Photomer 3005F, and the meth(acrylate) compound (B) such as pentaerythritol hexaacrylate to form varnishes (V1 to 20). The varnishes were stirred at 80°C and cooled to 25°C, and the compatibility was visually evaluated according to the following three-level scale.
(Evaluation criteria)
◯: Completely dissolved and becomes transparent.
△: Slight turbidity is observed.
×: Turbidity is observed.

[Evaluation item 2: Ink fluidity]
Ink fluidity was measured by the spreadmeter method (parallel plate viscometer) according to JIS K5101, 5701, and the ink sandwiched between two horizontally placed parallel plates was observed over time to spread concentrically due to the weight of the loaded plate (115 grams), and the diameter of the ink spread after 60 seconds was measured as the diameter value (DM [mm]). The ink printability was evaluated on the following five-point scale according to which the ink printability was good. In this evaluation item, compositions with a DM of less than 30 mm are prone to problems in printability, such as fountainhead breakage on the printing press and poor transfer between ink rollers.
(Evaluation criteria)
5: 40mm or more 4: 35 to less than 40mm 3: 30 to less than 35mm 2: 25 to less than 30mm 1: Less than 25mm

[Evaluation item 3: Viscoelasticity]
The obtained active energy ray curable offset black ink was used to evaluate the viscoelasticity based on the degree of paper peeling on an offset printing machine.
Using a Lithrone G40 manufactured by Komori Corporation equipped with a water-cooled metal halide lamp (output 160 W/cm, 3 lamps used) manufactured by Eye Graphics as an ultraviolet irradiation device, the clearance between the ink fountain and the fountain roller was adjusted to 2-3 μm, and the solid density of the solid part of the pattern was uniformly adjusted to an ink density of 1.7 (measured with a SpectroEye densitometer manufactured by X-Rite), and offset printing was performed at a printing speed of 15,000 sheets per hour. The printing paper used was OK Topcoat Plus (57.5 kg, A size) manufactured by Oji Paper Co., Ltd. The dampening water supplied to the plate surface was an aqueous solution made by mixing 98% by mass of tap water and 2% by mass of an etching solution (FST-700, manufactured by DIC Corporation). At that time, the degree of paper peeling of the printed matter was visually evaluated on the following 5-point scale.
(Evaluation criteria)
5: No peeling is observed on the printed matter.
4: Slight peeling of paper is observed on the print.
3: Some peeling of the paper is observed on the print.
2: Paper peeling is observed on the print.
1: Paper peeling of printed matter is noticeable.

Tables 2 to 5 show the evaluation results of the active energy ray-curable offset black inks.

The values in Tables 2 to 5 are percent by mass (solid content). The raw materials and abbreviations shown in each table are as follows:
Raven 1060Ultra: carbon black, manufactured by Birla Omnirad TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide, number average molecular weight 418.5, manufactured by IGM Omnirad EMK: 4,4'-bis(diethylamino)benzophenone, number average molecular weight 324.5, manufactured by IGM AR-1: Daiso DAP A: diallyl orthophthalate resin, average weight molecular weight 55,000: manufactured by Osaka Soda Co., Ltd. AR-2: Daiso Isodap: diallyl isophthalate resin, average weight molecular weight 50,000: manufactured by Osaka Soda Co., Ltd. AR-3: Variplus AP: polyketone oligomer, manufactured by Evonik AR-4: Laropal A81: urea-aldehyde resin, BASF High Filler #5000PJ: talc made of hydrated magnesium silicate, Matsumura Sangyo Co., Ltd. Hakuenka TDD: calcium carbonate, Shiraishi Kogyo Co., Ltd. Magnesium Carbonate TT: basic magnesium carbonate, Naikai Salt Industry Co., Ltd. Photomer 3005F: epoxidized soybean oil modified acrylate, CAS. No. 91722-14-4, IGM Resins B.V. Solsperse 24000: Basic dispersant with acid value, acid value 29 mg KOH/g, Lubrizol AJISPER PB-824: Basic dispersant with acid value, acid value 29 mg KOH/g, Ajinomoto Fine-Techno Co., Ltd. DPHA: Miramer M600: Dipentaerythritol hexaacrylate, dipentaerythritol pentaacrylate mixture (DPHA), MIWON DTMPTA: Miramer M410: Ditrimethylolpropane tetraacrylate, MIWON TMP(EO)3TA: Miramer M3130: Trimethylolpropane ethylene oxide modified triacrylate, MIWON

The active energy ray-curable ink for lithographic offset printing of the present invention has excellent compatibility between the binder resin and monomers used and the epoxidized soybean oil-modified acrylate, which is a plant-derived raw material, and has excellent ink flowability and viscoelasticity that does not peel off even when the substrate is paper.
In addition, for Comparative Examples 6 to 8, since Photomer 3005F (epoxidized soybean oil modified acrylate) was not used, the compatibility evaluation was omitted.

Claims (8)

(a) 5 to 70% by mass of a polyfunctional (meth)acrylate compound having 2 to 6 functional groups;
(b) 0.1 to 50% by mass of an aryl (meth)acrylate compound, (c) 5 to 40% by mass of a styrene compound, (d) 0.1 to 10% by mass of a polymerizable unsaturated bond-containing compound having a hydrophilic group, and (e) 0.1 to 10% by mass of a (meth)acrylate compound having a nitrogen-containing heterocyclic group,
(f) a copolymer (A) made of a polymer containing, as an essential polymerization component, 0.1 to 10% by mass of a (meth)acrylate compound having an alkylamino group (the total amount of (a) to (f) is 100% by mass);
As the (meth)acrylate compound (B), a vegetable oil-modified (meth)acrylate compound (B2) is used;
An extender pigment (D),
Polar group-containing pigment dispersant (E)
An active energy ray curable ink for lithographic offset printing, comprising: The active energy ray-curable ink for lithographic offset printing according to claim 1, wherein the copolymer (A) has a weight average molecular weight of 5,000 to 100,000, a PDI of the molecular weight of 3 to 35, and an acid value of 1 to 40 mg/KOH/g. The active energy ray curable ink for lithographic offset printing according to claim 1 or 2, wherein the mass ratio of the copolymer (A) to the (meth)acrylate compound (B) is in the range of 5:65 to 30:40. The active energy ray curable ink for lithographic offset printing according to any one of claims 1 to 3, which contains at least one selected from the group consisting of talc, magnesium carbonate, and calcium carbonate as the extender pigment (D). The active energy ray curable ink for lithographic offset printing according to any one of claims 1 to 4, containing, as the (meth)acrylate compound (B), a vegetable oil modified (meth)acrylate compound (B2) and a (meth)acrylate compound (B) other than the vegetable oil modified (meth)acrylate compound (B2). The active energy ray-curable ink for lithographic offset printing according to any one of claims 1 to 5, wherein the polar group-containing pigment dispersant (E) 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 6, and curing the printed ink using active energy rays. A printed matter characterized by having a cured product of the active energy ray-curable ink for lithographic offset printing described in any one of claims 1 to 6 on a substrate.