JP7844708B2 - Electron beam curable printing ink composition - Google Patents

Description

This invention relates to a method for manufacturing printed materials, printed materials, and electron beam-curable printing ink compositions.

In active energy ray-curing inks, diallyl phthalate resin (sometimes called "DAP resin" or "DAP resin") is used as one of the resin components. While diallyl phthalate resin itself is generally considered harmless, its raw material, diallyl phthalate, is a type of phthalate ester, and therefore a chemical substance of concern regarding its effects on human health and the environment. For this reason, in recent years, polymers of diallyl cyclohexanedicarboxylic acid, which are structurally similar, have been considered as alternative materials to diallyl phthalate resin.

Patent Document 1 discloses an active energy ray-curable ink composition characterized by comprising a compound having an ethylenically unsaturated bond, component (A) which is a polymer of an allyl monomer having a specific structure, and component (B) which is a rosin-modified resin and/or a terpene monomer skeleton-containing resin.

Patent Document 2 discloses an active energy ray curable ink composition containing (A) a pigment, (B) an allyl resin, (C) an epoxy compound, (D) an oxetane compound, and (E) a photocationic polymerization initiator, characterized by the following (1) to (3).
(1) The total amount of the ink composition contains (B) 3 to 25% by weight of allyl resin.
(2) The total amount of the ink composition contains 30 to 65% by weight of (C) epoxy compound and (D) oxetane compound.
(3) The weight ratio expressed as (C) epoxy compound / (D) oxetane compound is in the range of 1 to 5.

Japanese Patent Publication No. 2023-121316 Japanese Patent Publication No. 2023-161230

However, in the case of prior art, including Patent Documents 1 and 2, there is still room for further improvement in achieving a balance between the required characteristics of ink, such as fluidity, storage stability, and curability, as well as odor suppression, abrasion resistance, tape adhesion, and lamination suitability of printed materials.

This invention has been made in view of the circumstances described above, and aims to provide a method for manufacturing printed materials, a printed material, and an electron beam-curable printing ink composition that can achieve both ink fluidity, storage stability, and curability, as well as odor suppression, abrasion resistance, tape adhesion, and lamination suitability of the printed material.

As a result of diligent research to achieve the above-mentioned objectives, the inventors of the present invention have found an electron beam-curable printing ink composition containing (A) a polymer of an allyl monomer having a specific structure, (B) a (meth)acrylate resin, (C) a polyfunctional (meth)acrylate, and (D) a pigment, thereby completing the present invention.

In other words, the present invention is as follows.
<1>
A method for producing a printed material, comprising: a printing step of printing on a printing target using an electron beam curable printing ink composition containing (A) a polymer of an allyl monomer represented by the following general formula (1), (B) a (meth)acrylate resin, (C) a polyfunctional (meth)acrylate, and (D) a pigment; and a curing step of curing the printed electron beam curable printing ink composition by irradiating it with an electron beam under conditions where the acceleration voltage is 50 to 150 kV, the irradiation dose is 15 to 50 kGy, and the oxygen concentration is 300 ppm or less.

(In general formula (1), ^R1 and ^R2 are each independently a hydrogen atom or a carbon atom having 1 to 5 carbon atoms)
X represents an alkyl group, where X represents an n-valent group having a 4-8 membered alipid ring skeleton, and n is 2
(Or it is 3.)
<2>
The method for producing a printed article according to <1>, wherein component (B) is at least one selected from the group consisting of epoxy (meth)acrylate resin, polyester (meth)acrylate resin, and urethane (meth)acrylate resin.
<3>
The method for producing a printed article according to <1> or <2>, wherein the content of component (A) in the electron beam curable printing ink composition is 3 to 30% by mass.
<4>
The method for producing a printed article according to <1> or <2>, wherein the content of component (B) in the electron beam curable printing ink composition is 5 to 60% by mass.
<5>
The method for producing a printed article according to <1> or <2>, wherein the content of component (C) in the electron beam curable printing ink composition is 5 to 60% by mass.
<6>
The electron beam curable printing ink composition is a method for producing a printed article according to <1> or <2>, wherein the electron beam curable printing ink composition does not contain a polymerization initiator.
<7>
The method for producing a printed article according to <1> or <2> is wherein the electron beam curable printing ink composition is an offset printing ink composition.
<8>
The method for producing a printed article according to <1> or <2> is wherein the electron beam curable printing ink composition is a surface printing ink composition.
<9>
The method for producing a printed article according to <1> or <2> is wherein the electron beam curable printing ink composition is a reverse printing ink composition.
<10>
The printed material is obtained by the method for manufacturing printed materials described in <1> or <2>.
<11>
This is an electron beam curable printing ink composition that contains (A) a polymer of an allyl monomer represented by the following general formula (1), (B) a (meth)acrylate resin, (C) a polyfunctional (meth)acrylate, and (D) a pigment, and is used for curing under curing conditions where the acceleration voltage is 50 to 150 kV, the irradiation dose is 15 to 50 kGy, and the oxygen concentration is 300 ppm or less.
(In general formula (1), ^R1 and ^R2 each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X represents an n-valent group having a 4 to 8-membered anticyclic ring skeleton, and n is 2 or 3.)

According to the present invention, it is possible to provide a method for manufacturing printed materials, printed materials, and an electron beam-curable printing ink composition that can achieve both ink fluidity, storage stability, and curability, as well as odor suppression, abrasion resistance, tape adhesion, and lamination suitability of printed materials.

The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be appropriately modified and implemented within the scope of its gist.

Furthermore, unless otherwise specified in this specification, "(meth)acrylate" encompasses both acrylate and methacrylate. For example, "(meth)acrylate" means acrylate, methacrylate, or both. The same applies to other similar terms such as "(meth)acrylic."

<Manufacturing Method for Printed Materials>

The method for manufacturing printed materials according to this embodiment includes a printing step of printing on a printing target using an electron beam-curable printing ink composition containing (A) a polymer of an allyl monomer represented by the following general formula (1), (B) a (meth)acrylate resin, (C) a polyfunctional (meth)acrylate, and (D) a pigment; and a curing step of curing the printed electron beam-curable printing ink composition by irradiating it with an electron beam under conditions where the acceleration voltage is 50 to 150 kV, the irradiation dose is 15 to 50 kGy, and the oxygen concentration is 300 ppm or less. This manufacturing method ensures at least the fluidity, storage stability, and curability of the ink, as well as the suppression of odor, abrasion resistance, tape adhesion, and lamination suitability of the printed material. The following describes each component and condition.

(In general formula (1), ^R1 and ^R2 each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X represents an n-valent group having a 4 to 8-membered anticyclic ring skeleton, and n is 2 or 3.)

<Electron beam curable printing ink composition>

The electron beam-curable printing ink composition used in the method for manufacturing printed materials according to this embodiment (hereinafter sometimes simply referred to as "ink composition") is an electron beam-curable printing ink composition containing (A) a polymer of an allyl monomer represented by the above general formula (1), (B) a (meth)acrylate resin, (C) a polyfunctional (meth)acrylate, and (D) a pigment.

Electron beam-curable printing ink compositions possess the ability to harden upon irradiation with active energy rays such as ultraviolet light or electron beams. As described later, these electron beam-curable printing ink compositions contain compounds with ethylenically unsaturated bonds (e.g., monomers and oligomers), and hardening occurs when radicals generated in the ink composition upon irradiation with active energy rays increase the molecular weight of the compounds with ethylenically unsaturated bonds. Therefore, when an active energy ray is irradiated onto an ink composition that is still sticky on the surface of a printed material immediately after printing, the ink composition instantly hardens to form a film and becomes dry (tack-free). From this perspective, electron beam-curable printing ink compositions can achieve the desired effects even without containing polymerization initiators such as photopolymerization initiators (however, the effects and properties of this embodiment are not limited to these).

The electron beam-curable printing ink composition, by containing components (A), (B), (C), and (D) described above, exhibits excellent fluidity, storage stability, and curability in the ink itself, and superior odor suppression, abrasion resistance, tape adhesion, and lamination suitability in printed materials using this ink. Thus, the electron beam-curable printing ink composition possesses at least the above-mentioned advantages regardless of the printing method, and also exhibits excellent water-to-weight compatibility and density stability, making it suitable as an ink composition for offset printing (e.g., offset printing ink composition, electron beam-curable offset printing ink composition, etc.). Further details will be described later.

<(A) Polymers of allyl monomers>

The electron beam-curable printing ink composition contains component (A), which is a polymer of an allyl monomer represented by the following general formula (1). This polymer is obtained by polymerizing the allyl monomer represented by the following general formula (1) by means of radical polymerization or other methods. The completely polymerized polymer may be used as an inert resin binder, or the polymerization reaction may be stopped at approximately 50% to 80% to leave unreacted unsaturated bonds, which may then be used as the curable component.

In general formula (1), ^R1 and ^R2 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. In this specification, "each independently" means that each is determined independently of the other, and they may be the same or different. Examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, and pentyl groups. In a preferred embodiment, both ^R1 and ^R2 are hydrogen atoms, but this is not particularly limited.

In general formula (1), n is 2 or 3, and X is an n-valent group having a 4- to 8-membered alipid ring skeleton. "An n-valent group having a 4- to 8-membered alipid ring skeleton" means an n-valent group formed by the formation of bonds between n carbon atoms and other groups from among the carbon atoms constituting the 4- to 8-carbon alipid ring. X may have an alipid ring skeleton and may also contain other skeletons, but a 4- to 8-carbon alipid ring skeleton is preferred. Furthermore, a 4- to 8-carbon cycloalkane or cycloalkene is preferred as the alipid ring of X. X may also be intramolecularly cross-linked; examples of intramolecularly cross-linked X include adamantane, norbornene, norbornane, etc.

More specifically, it is preferable that X is a divalent group represented by one of the following general formulas. In this case, n in general formula (1) is 2.

Among the X groups represented by the above general formula, the 1,2-cyclohexalene group is preferred. In this case, the 1st and 2nd positions of cyclohexane are substituted with the group represented by the parenthetical portion of general formula (1).

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

Allyl monomers represented by general formula (1) are obtained by dehydration condensation and esterification of a carbon-4 to carbon-8 cycloalkane or cycloalkene having two or three carboxyl groups with an allyl alcohol having substituents ^R1 and ^R2 . As previously mentioned, it is preferable that substituents ^R1 and ^R2 are both hydrogen atoms.

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

The amount of radical polymerization initiator is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 0.001 to 3 parts by mass, per 100 parts by mass of the allyl monomer represented by general formula (1). The reaction temperature during polymerization is not particularly limited, but is usually around 60 to 240°C. The reaction time is typically around 0.1 to 100 hours.

Furthermore, when polymerizing the allyl monomer represented by general formula (1) to obtain a polymer, a homopolymer using a single allyl monomer may be used, or a copolymer combining multiple allyl monomers or other monomers may be used. In the copolymer, other monomers copolymerizable with the above allyl monomer are not particularly limited, but examples include 3-methyl-hexahydro-1,2-diallyl phthalate, 4-methyl-hexahydro-1,2-diallyl phthalate, 3-methyl-1,2,3,6-tetrahydro-1,2-diallyl phthalate, and 4-methyl-1,2,3,6-tetrahydro-1,2-diallyl phthalate. A preferred embodiment in this example is a homopolymer of diallyl 1,2-cyclohexanedicarboxylic acid, but is not particularly limited.

The weight-average molecular weight of the polymer is not particularly limited, but is preferably between 2,000 and 300,000. The lower limit is more preferably 5,000 or more, and even more preferably 10,000 or more. The upper limit is more preferably 200,000 or less, even more preferably 150,000 or less, and even more preferably 140,000 or less. Unless otherwise specified, the weight-average molecular weight refers to the weight-average molecular weight ( _Mw ) in polystyrene terms, obtained by gel permeation chromatography (GPC) analysis.

Furthermore, the polymer used may be one synthesized as described above, or a commercially available product may be used. An example of such a commercially available product is one manufactured by Osaka Soda Co., Ltd.

(A) Component may be used alone or in combination of two or more components.

The content of component (A) relative to the total electron beam-curable printing ink composition is not particularly limited, but is preferably 3 to 30% by mass. The lower limit is more preferably 5% by mass or more, and even more preferably 10% by mass or more. The upper limit is more preferably 25% by mass or less, and even more preferably 15% by mass or less. If the electron beam-curable printing ink composition in this embodiment contains a solvent, the above content is preferably the content when the total solid content is considered to be 100% by mass.

<(B) (Meth)acrylate resin>

Electron beam curable printing ink compositions contain (meth)acrylate resins. Examples of (meth)acrylate resins include resins having a (meth)acrylate skeleton with one or more functional groups selected from the group consisting of epoxy groups, ester groups, ether groups, and urethane groups. Specific examples include epoxy (meth)acrylate resins, polyester (meth)acrylate resins, urethane (meth)acrylate resins, and polyether (meth)acrylate resins.

Among these, it is preferable that component (B) is at least one selected from the group consisting of epoxy (meth)acrylate resin, polyester (meth)acrylate resin, and urethane (meth)acrylate resin. Using these components can further improve the adhesion of the ink coating and the lamination suitability of the printed material.

Epoxy (meth)acrylate resins can be, for example, aromatic (meth)acrylate resins having a bisphenol skeleton, or aliphatic (meth)acrylate resins having a hydrogenated bisphenol skeleton. Commercially available products may also be used.

Polyester (meth)acrylate resins can be, for example, aliphatic polyester (meth)acrylates or aromatic polyester (meth)acrylates. Commercially available products may also be used.

Examples of urethane (meth)acrylate resins that can be used include polyester urethane (meth)acrylate, polyether urethane (meth)acrylate, and polycarbonate urethane (meth)acrylate. Commercially available products may also be used.

(B) Component may be used alone or in combination of two or more components.

The content of component (B) relative to the total electron beam-curable printing ink composition is not particularly limited, but is preferably 5 to 60% by mass. The lower limit is more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit is more preferably 50% by mass or less, and even more preferably 40% by mass or less. If the electron beam-curable printing ink composition in this embodiment contains a solvent, the above content is preferably the content when the total solid content is considered to be 100% by mass.

<(C) Polyfunctional (meth)acrylate>

The electron beam curable printing ink composition contains (C) a polyfunctional (meth)acrylate. The polyfunctional (meth)acrylate compound can enhance the electron beam curability of the ink composition. Polyfunctionality refers to the number of (meth)acrylate groups contained in one molecule, and it is preferable that it be bifunctional to hexafunctional.

(C) Specific examples of component are not particularly limited, but include, for example, 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, tricyclodecanedimethanol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di Di(meth)acrylates of dihydric alcohols such as (meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; di(meth)acrylate of polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, tris(2-hydroxyethyl) isocyanurate di(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 neopentyl glycol. , 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 trivalent 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 dipentaerythritol poly(meth)acrylate; 3 moles or more of ethylene oxide to 1 mole of glycerin Examples include poly(meth)acrylates of polyoxyalkylene polyols such as triol triacrylates obtained by adding dimethylol or propylene oxide, 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; vegetable oil (e.g., soybean oil) modified epoxy acrylates; and urethane acrylates.

Among these, alkylene oxide-modified trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, alkylene oxide-modified glycerin (meth)acrylate, soybean oil-modified acrylate, and urethane acrylate are preferred; ditrimethylolpropane tetra(meth)acrylate, tri(meth)acrylate of a 3-mol ethylene oxide adduct of trimethylolpropane, tri(meth)acrylate of a 6-mol ethylene oxide adduct of trimethylolpropane, tri(meth)acrylate of a 3-mol propylene oxide adduct of trimethylolpropane, tri(meth)acrylate of a 3-mol propylene oxide adduct of glycerin, and dipentaerythritol hexaacrylate are more preferred.

(C) Component may be used alone or in combination of two or more types.

Component (C) is preferably a compound with a low glass transition temperature (for example, preferably 100°C or lower, more preferably 60°C or lower). A low glass transition temperature for component (C) can improve the lamination suitability of the ink composition. Specific examples of (meth)acrylate compounds with a low glass transition temperature include, but are not limited to, 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. Furthermore, when two or more components are used in combination as component (C), it is preferable, for example, that 50% by mass or more of component (C) is a compound with a low glass transition temperature, and more preferably that 60% by mass or more of component (C) is a compound with a low glass transition temperature.

The content of component (C) in the total electron beam-curable printing ink composition is not particularly limited, but is preferably 5 to 60% by mass. The lower limit is more preferably 10% by mass or more, and even more preferably 20% by mass or more. The upper limit is more preferably 55% by mass or less, and even more preferably 50% by mass or less. If the electron beam-curable printing ink composition in this embodiment contains a solvent, the above content is preferably the content when the total solid content is considered to be 100% by mass.

<(D) Pigments>

The electron beam-curable printing ink composition contains (D) a pigment. The type of (D) pigment is not particularly limited, but examples include inorganic pigments and organic pigments. Specific examples of inorganic pigments include coloring pigments such as carbon black, graphite, antimony red, cadmium yellow, cobalt blue, Prussian blue, ultramarine, and titanium dioxide (including achromatic coloring pigments such as white and black); and extender pigments such as graphite, zinc, calcium carbonate powder, calcium carbonate, gypsum, clay, silica (silicon dioxide), diatomaceous earth, talc, kaolin, alumina white, barium sulfate, aluminum stearate, magnesium carbonate, magnesium silicate, barite powder, and glass beads. Specific examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments.

(D) Component may be used alone or in combination of two or more components.

Furthermore, extender pigments can more effectively adjust the rheological properties of the ink composition. Additionally, by localizing on the surface (outer surface) of the cured film formed by the ink composition, extender pigments can be expected to effectively prevent sticking of printed materials (however, the effects and benefits of this embodiment are not limited to these).

Furthermore, one preferred example of an extender pigment is one containing at least (D-1) calcium carbonate, magnesium carbonate, or magnesium silicate, and (D-2) silica (silicon dioxide) in combination. Such a combination, in conjunction with other components, can more effectively suppress the stringiness (tendency to string) of the ink composition. The content ratio (mass ratio) of component (D-1) to component (D-2) is not particularly limited, but is preferably 10:1 to 1:1, more preferably 10:1 to 2:1, even more preferably 10:1 to 4:1, and even more preferably 10:1 to 6:1.

The content of the extender pigment in component (D) relative to the entire electron beam-curable printing ink composition is not particularly limited, but is preferably 0.1 to 10% by mass. The lower limit is more preferably 1% by mass or more, and even more preferably 2% by mass or more. The upper limit is more preferably 8% by mass or less, and even more preferably 6% by mass or less. If the electron beam-curable printing ink composition in this embodiment contains a solvent, the above content is preferably the content when the total solid content is considered to be 100% by mass.

<(E) Other ingredients, etc.>

The electron beam curable printing ink composition may optionally contain other components besides those listed above, as long as their function and effects are obtained. Examples of other components include colorants other than component (D), pigment dispersants, waxes, polymerization inhibitors, surfactants, solvents, etc.

Other colorants besides component (D) include, for example, dyes. Examples of dyes include basic reaction-type lakes, acid dye-type lakes, and nitro pigments.

Examples of pigment dispersants include polymer-based pigment dispersants. Preferably, the polymer-based pigment dispersant is a pigment dispersant containing basic groups. Specific examples of pigment dispersants containing basic groups include polymer-based pigment dispersants such as basic group-containing polyester-based pigment dispersants, basic group-containing acrylic-based pigment dispersants, basic group-containing urethane-based pigment dispersants, and basic group-containing carbodiimide-based pigment dispersants; and anionic surfactants. While the polymer-based pigment dispersant is not particularly limited, a linear polymer having a pigment-affinity portion consisting of basic groups at at least one or both ends of the main chain via a block structure or graft structure can be used.

Examples of waxes include animal and plant-based waxes such as beeswax, lanolin wax, whale wax, candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil; mineral and petroleum-based waxes such as montane wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, and petrolatum; synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene wax, oxidized polyethylene wax, and oxidized polypropylene wax; fluororesin-based waxes such as polytetrafluoroethylene wax; mixtures of polytetrafluoroethylene wax and polyethylene wax; modified waxes such as montane wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives; hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives; and polytetrafluoroethylene wax.

Polymerization inhibitors can effectively prevent unintended polymerization reactions from occurring during storage of the ink composition and effectively suppress the thickening of the ink composition. Examples of polymerization inhibitors include phenolic compounds (including quinone compounds) such as dibutylhydroxytoluene (BHT), tocopherol acetate, nitrosamine compounds, benzotriazole, and hindered amines. Among these, phenolic compounds such as dibutylhydroxytoluene are preferred. The content of the polymerization inhibitor in the ink composition can be appropriately set depending on the type of polymerization inhibitor, but for example, in the case of phenolic compounds such as dibutylhydroxytoluene (BHT), it may be about 0.3 to 2.0 parts by mass when the total curable component is 100 parts by mass.

Examples of surfactants include nonionic surfactants, cationic surfactants, anionic surfactants, and betaine surfactants. Specific examples of surfactants include silicone-based surfactants such as polyether-modified silicone oil, polyester-modified polydimethylsiloxane, and polyester-modified methylalkylpolysiloxane, as well as fluorine-based surfactants and acetylene-based surfactants.

Electron beam curable printing ink compositions can be cured by irradiation with an electron beam even without containing a polymerization initiator. Therefore, the ink composition may or may not contain a polymerization initiator, but it is preferable that it does not. Specific examples of such polymerization initiators, other than those mentioned above, include acylphosphine oxide compounds, thioxanthone compounds, aromatic ketones, aromatic onium salt compounds, organic peroxides, thio compounds (such as thiophenyl group-containing compounds), α-aminoalkylphenone compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having carbon-halogen bonds, and alkylamine compounds.

The electron beam curable printing ink composition may or may not contain a solvent such as water or an organic solvent. The solvent may be present in small amounts, for example, 3% by mass or less relative to the mass of the ink composition. Unless otherwise specified, when the electron beam curable printing ink composition in this embodiment contains a solvent, the content values described herein preferably represent the content when the total solid content is considered to be 100% by mass.

The viscosity of the electron beam-curable printing ink composition is preferably 100.0 Pa·s or less, and more preferably between 1.0 Pa·s and 90.0 Pa·s. This viscosity may be measured using a cone-plate viscometer at 25°C and a shear rate of 100/s. By having this viscosity within the above range, the fluidity and transferability of the ink composition are further improved, which is expected to enhance the stability of the ink composition supplied to the roller in offset printing and improve printability. Furthermore, by having this viscosity within the above range, the leveling properties of the ink composition transferred to the printing target (substrate, etc.) are further improved, which is expected to more effectively suppress quality defects such as gloss degradation. Moreover, by having the viscosity of the ink composition within the above range, the tack value of the ink can be more easily controlled to a suitable value, which is expected to effectively suppress transfer defects to the printing target and ensure stable printability.

Electron beam curable printing ink compositions have the property of curing when irradiated with an electron beam (curability). From this viewpoint, it is preferable that the electron beam curable printing ink composition contains (A) a polymer of an allyl monomer represented by the above general formula (1), (B) a (meth)acrylate resin, (C) a polyfunctional (meth)acrylate, and (D) a pigment, and is used for curing under curing conditions where the acceleration voltage is 50 to 150 kV, the irradiation dose is 15 to 50 kGy, and the oxygen concentration is 300 ppm or less. The degree of curability is not particularly limited, but for example, it is preferable that it is completely cured at an irradiation dose of 20 to 40 kGy when formed into a coating film.

<Method for Manufacturing Electron Beam Curable Printing Ink Composition>

An electron beam-curable printing ink composition can be obtained by a process of mixing components (A) to (D) described above and, if necessary, other components (such as component (E)). For example, it can be obtained by dissolving a polymer of (A) an allyl monomer or a (B) (meth)acrylate resin in (C) a polyfunctional (meth)acrylate, dispersing a pigment (D), and mixing in other arbitrary components (such as component (E)). The mixing method is not particularly limited.

<Printing process, curing process, printed matter, etc.>

In the method for manufacturing printed materials according to this embodiment, a printing step is performed to print on a printing target, followed by a curing step in which the printed electron beam-curable printing ink composition is cured by irradiation with an electron beam. In the printing step, a suitable method can be appropriately selected depending on the materials used and the application; for example, a method of applying the electron beam-curable printing ink composition to the printing target can be employed. Furthermore, the printing method in the printing step is not particularly limited, and various methods described later can be employed. In the curing step, the electron beam is irradiated under conditions where the acceleration voltage is 50 to 150 kV, the irradiation dose is 15 to 50 kGy, and the oxygen concentration is 300 ppm or less. The material of the printing target (substrate) is not particularly limited as long as the ink composition can be electron beam-cured on the object, and can be appropriately selected according to the application. However, by keeping the acceleration voltage, irradiation dose, and oxygen concentration within the above ranges, the various advantages of this embodiment described above can be effectively realized.

The acceleration voltage can be 50 to 150 kV as described above, but the lower limit is preferably 60 kV or higher, more preferably 70 kV or higher, and even more preferably 80 kV or higher. The upper limit is preferably 140 kV or lower, more preferably 130 kV or lower, and even more preferably 110 kV or lower.

The irradiation dose should be between 15 and 50 kGy, as described above, but the lower limit is preferably 20 kGy or higher. Furthermore, the upper limit is preferably 40 kGy or lower.

As mentioned above, the oxygen concentration should be 300 ppm or less, but the upper limit is preferably 250 ppm or less, more preferably 200 ppm or less, and even more preferably 150 ppm or less. The lower limit is preferably 50 ppm or more, more preferably 70 ppm or more, and even more preferably 80 ppm or less.

Furthermore, the method for manufacturing printed materials according to this embodiment is excellent in terms of water-to-weight compatibility and density stability, making it suitable for offset printing. From this viewpoint, offset printing is preferred for the method of manufacturing printed materials according to this embodiment. For example, a manufacturing method is exemplified that includes a step of offset printing an electron beam-curable printing ink composition onto a printing target (offset printing step), and a step of curing the offset-printed electron beam-curable printing ink composition by irradiating it with an electron beam (curing step). The printing method of this embodiment will be described illustratively below, using offset printing as an example, but it goes without saying that it is not limited to the following embodiments.

The printing target in the offset printing process is not particularly limited and includes substrates such as resin substrates, metal substrates, and paper substrates. Specific examples of metals used in metal substrates include aluminum, zinc, copper, iron, and tin. Specific examples of paper substrates include synthetic paper, art paper, coated paper, cast paper, newsprint, resin-laminated paper, metal-deposited paper, and metal oxide-deposited paper.

Considering the effects and benefits of this embodiment, such as improved adhesion to the printing target and lamination suitability, a resin substrate, particularly a resin film, is sometimes preferable. The type of resin constituting the resin substrate is not particularly limited, but examples include films or sheets of polyester resin (e.g., polyethylene terephthalate), 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, cellophane, aluminum foil, and various other resins conventionally used as printing targets (substrates to be printed). The resin film may be subjected to stretching (uniaxial stretching, biaxial stretching, etc.).

The offset printing process may be carried out in accordance with known printing methods, but examples include a method that includes: (a) a step of supplying the electron beam-curable printing ink composition and dampening water according to this embodiment to the printing plate; (b) a step of transferring the ink composition supplied to the plate to the blanket (offset step); and (c) a step of fixing the ink composition transferred to the blanket to the printing object (set step).

The dampening solution supplied to the printing plate is a water-based solution, and may contain other optional components. Specific examples of these optional components include pH adjusters, water-soluble organic solvents, chelate compounds, and water-soluble polymers.

In step a, where the ink composition and dampening solution are supplied to the printing plate, for example, the ink composition can be supplied to the plate wrapped around the plate cylinder via an ink roller, and the dampening solution via a water supply roller. The printing plate typically has areas where the ink composition adheres (lipophilic image areas) and areas where the dampening solution adheres (hydrophilic non-image areas). While the ink composition adheres to the image areas of the plate, the adhering ink composition may be an emulsion of the ink composition and dampening solution (water-in-oil emulsion).

The ink composition (or emulsion with dampening solution) adhering to the image area of the plate is transferred to the blanket (step b). The dampening solution adhering to the non-image area of the plate is collected without being transferred to the blanket cylinder. Furthermore, the ink composition (or emulsion with dampening solution) transferred to the blanket is typically pressed against the printing target (substrate, etc.) by the impression cylinder, fixing to the printing target and forming a coating (step c).

The coating film formed on the printing target by offset printing hardens upon irradiation with an electron beam, becoming a cured film and fixing as an image. In offset printing, the acceleration voltage of the electron beam is preferably in the range of 80 to 150 kV, and more preferably in the range of 80 to 110 kV, from the viewpoint of effectively suppressing the penetration of the electron beam into the printing target and minimizing damage to the printing target. Furthermore, the irradiation dose of the electron beam is preferably in the range of 20 to 40 kGy, from the viewpoint of reliably hardening the coating film while suppressing poor adhesion to the substrate by preventing excessive hardening. It is preferable to appropriately set the upper limits of these parameters from the viewpoint of effectively preventing damage to the printing target (substrate, etc.) due to high irradiation doses and high acceleration voltages.

Furthermore, according to this embodiment, printed materials can also be obtained by printing using the method described above. The various conditions for the printing process can be appropriately selected from the various conditions described above. The printed materials obtained by the manufacturing method according to this embodiment exhibit excellent odor suppression, abrasion resistance, tape adhesion, and lamination suitability.

<Applications of ink compositions and printed materials>

The method for manufacturing printed materials according to this embodiment involves printing and curing a printed layer on a printing target to produce a printed material. This method may be used for reverse-printed materials (reverse-printing ink composition), front-printed materials (front-printing ink composition), or other printing methods. For front-printed materials, for example, the manufacturing method includes a step of front-printing an electron beam-curable printing ink composition onto a printing target (front-printing step), and a step of curing the front-printed electron beam-curable printing ink composition by irradiating it with an electron beam (curing step). Similarly, for reverse-printed materials, the manufacturing method includes a step of back-printing an electron beam-curable printing ink composition onto a printing target (reverse-printing step), and a step of curing the back-printed electron beam-curable printing ink composition by irradiating it with an electron beam (curing step).

In the case of surface printing (or surface printing ink composition), the printed layer is exposed on the surface of the printed material, therefore, high adhesion between the substrate and the printed layer is required. In this regard, the electron beam-curable printing ink composition according to this embodiment exhibits excellent adhesion, among other qualities. Therefore, the printed layer (printed portion) obtained from this ink composition has high adhesion to the substrate and can be suitably used in surface printing.

In the case of reverse printing (or reverse printing ink composition), the printed material is generally obtained as a laminate by laminating a laminate layer that covers the printed layer. Therefore, printed materials obtained by reverse printing require high lamination suitability (the laminate layer must not peel off easily). In this respect, the method for manufacturing printed materials according to this embodiment is excellent in terms of lamination suitability, etc., so the printed layer obtained from this ink composition can be strongly bonded to the laminate layer via an adhesive, etc., making it suitable for use in reverse printing.

In other words, by fixing the cured product of the electron beam-curable printing ink composition according to this embodiment onto a substrate film, which is the substrate to be printed on, to form an image, applying an adhesive to cover the cured product to form an adhesive layer, and then laminating a sealant layer onto the adhesive layer, a laminate film (a laminated film comprising the substrate film, the cured product layer of the ink composition, the adhesive layer, and the sealant layer in this order) can be obtained.

The substrate film, which is the printing substrate, is preferably made of resin, but is not particularly limited and can be selected according to the intended use of the resulting laminate film. The adhesive layer is a cured product of an adhesive composition, but the composition of the adhesive composition is not particularly limited. The sealant layer, which is arranged to cover the adhesive layer, is preferably made of resin, for example, polyolefin, but can be selected according to the intended use of the laminate film.

The sealant layer may be formed by dry lamination, solvent-free lamination, or extrusion lamination. In order to effectively exhibit the effects of the electron beam-curable printing ink composition according to this embodiment (high adhesion to the substrate and high lamination suitability), it is sometimes preferable to form the sealant layer by the dry lamination method.

The laminate film obtained in this manner has the advantage of easily ensuring sufficient lamination suitability because it exhibits high adhesion between the substrate to be printed and the cured ink composition layer, as well as high adhesion between the cured ink composition layer and the adhesive layer. Furthermore, the resulting laminate film can be used for a wide range of applications, such as food packaging and food preservation packaging.

As described above, the method for manufacturing printed materials, the printed materials, and the electron beam-curable printing ink composition according to this embodiment can achieve a balance between ink fluidity, storage stability, and curability, as well as odor suppression, abrasion resistance, tape adhesion, and lamination suitability of the printed materials. These advantages are expected to be evident in a wide range of printing methods. In addition, because of its excellent water-to-weight compatibility and density stability, it can be suitably used in offset printing, which allows for quick, easy, and high-volume printing of clear prints.

Furthermore, the method for manufacturing printed materials, the printed materials, and the electron beam-curable printing ink composition according to this embodiment can be suitably used for both front-side and back-side printing. For example, in the case of package printing, front-side printing involves printing on the front side of the package (bag). The electron beam-curable printing ink composition according to this embodiment is expected to effectively suppress problems such as ink rubbing off.

Furthermore, in the case of reverse printing, the printing is done from the back of a transparent material such as a bag, and then covered by a laminate layer. This printed layer is then visible to the user from the front through the transparent material. In this respect, the electron beam-curable printing ink composition according to this embodiment exhibits excellent lamination properties. Therefore, even if the contents require safety, such as food, the lamination effect is sufficiently maintained, and it can be expected that the contents will be preserved safely and hygienically for a long period of time without the ink components contaminating them.

As described above, the method for manufacturing printed materials, the printed materials, and the electron beam-curable printing ink composition according to this embodiment can be suitably used in a wide range of printing methods, but they are particularly advantageous in offset printing. They are also suitable for printing food packaging and food preservation packaging. Note that the term "food" here is not limited to its shape or contents, and can include solid, semi-solid, fluid, and liquid foods as preservation targets.

The present invention will be described in more detail below with reference to examples, but these examples are not intended to limit the scope of the present invention. The numerical values for the formulations shown in each table are in parts by mass.

<Preparation of electron beam-curable printing ink composition>

First, the material components used to prepare the electron beam-curable printing ink compositions for each example and comparative example are shown below.

(resin)
- AD-032: A homopolymer of 1,2-cyclohexanedicarboxylate diallyl (see formula (i) below) (product name "RADPAR-AD032", manufactured by Osaka Soda Co., Ltd., non-phthalate type allyl resin)

• A-DAP: Homopolymer of diallyl phthalate (product name "Daiso DAP A", manufactured by Osaka Soda Co., Ltd.)
VS-1063: Polystyrene (Product name "VS-1063", polystyrene, weight-average molecular weight ( _Mw ) 5,500, manufactured by Seikoh PMC Co., Ltd.)
• ISODAP: Homopolymer of diallyl isophthalate (product name "Daiso ISODAP", manufactured by Osaka Soda Co., Ltd.)

(Polymerizable compound (polyfunctional))
• M410: Ditrimethylolpropanetetraacrylate (product name "MIRAMER M410", manufactured by Miwon)
• M3130: Triacrylate of the ethylene oxide 3-mol adduct of trimethylolpropane (product name "MIRAMER M3130", manufactured by Miwon)
• M3160: Triacrylate of the 6-mol ethylene oxide adduct of trimethylolpropane (product name "MIRAMER M3160", manufactured by Miwon)
• M360: Triacrylate of a 3-mol propylene oxide adduct of trimethylolpropane (product name "MIRAMER M360", manufactured by Miwon)
• M320: Triacrylate of a 3-mol adduct of glycerin with propylene oxide (product name "MIRAMER M320", manufactured by Miwon)
• M600: Dipentaerythritol hexaacrylate (product name "MIRAMER M600", manufactured by Miwon)

(Polymerizable compound (monofunctional))
• IBXA: Isobornyl acrylate (product name "IBXA", manufactured by Osaka Organic Chemical Industry Co., Ltd.)

(Meth)acrylate resins
PE210: Bisphenol A skeleton-containing epoxy diacrylate (product name "MIRAMER PE210", manufactured by Miwon)
• 623-100: Bisphenol A skeleton-containing epoxy acrylate (product name "ETERCURE 623-100", manufactured by Eternsl Materials)
EBECRYL600: Aromatic epoxy acrylate (product name "EBECRYL600", manufactured by Daicel Ornex Co., Ltd.)
EBECRYL3700: Aromatic epoxy acrylate (product name "EBECRYL3700", manufactured by Daicel Ornex Co., Ltd.)
EBECRYL3702: Fatty acid modified epoxy acrylate (product name "EBECRYL3702", manufactured by Daicel Ornex Co., Ltd.)
PE310: Soybean oil-modified epoxy acrylate (product name "MIRAMER PE310", manufactured by Miwon Co., Ltd.)
EBECRYL438: A mixture of 60 parts by mass of chlorinated polyester acrylate and 40 parts by mass of glycerin propoxy triacrylate (product name "EBECRYL438", manufactured by Daicel Ornex Co., Ltd.)
DR-U161: Aliphatic urethane acrylate (product name "ETERCURE DR-U161", manufactured by Eternsl Materials)

(Body pigments)
• T-DD: Calcium carbonate (product name "Hakutsuka T-DD", manufactured by Shiraishi Calcium Co., Ltd.)
• L-1: Talc (product name "L-1", manufactured by Nippon Talc Co., Ltd.)
CP-102: Silica (product name "Rheoroseal CP102", manufactured by Tokuyama Corporation)

(Other pigments)
• MA-70: Carbon black (product name "MA-70", manufactured by Mitsubishi Chemical Corporation)

(Pigment dispersant)
• Solspers 33000: Basic functional group-containing copolymer (amine value 43.0 mg KOH/
(g, acid value 27 mg KOH/g, active ingredient 100% by mass, manufactured by Lubrizol Japan Co., Ltd.)

(wax)
MG: Synthetic wax (product name "S-394 MG", manufactured by Shamrock Technologies)

(Polymerization inhibitor)
BHT: Dibutylhydroxytoluene

(film)
• OPP: Stretched polypropylene film (product name "P2161", manufactured by Toyobo Co., Ltd.)
PE: Uniaxially oriented polyethylene film (manufactured by JINDAL Co., Ltd.)
• OPA: Stretched nylon film (product name "Emblem ONM-15", manufactured by Unitika Corporation)
PET: Polyethylene terephthalate film (product name "E-5102", manufactured by Toyobo Co., Ltd.)

The electron beam-curable printing ink compositions (ink compositions) for each example and comparative example were obtained by blending each component to the composition shown in each table (unless otherwise specified, by mass %) and kneading the mixture in a three-roll mill.

<Evaluation Method>

The electron beam-curable printing ink compositions (ink compositions) and printed materials of each example and comparative example were evaluated according to the following procedure.

(Assessment of liquidity)
For each example and comparative example ink composition, the flow value was measured using a spread meter, and the fluidity was evaluated as a flow slope value. The flow slope value is calculated by subtracting the spread diameter measured in millimeters after 10 seconds from the spread diameter measured in millimeters after 100 seconds using a spread meter. A larger value indicates better fluidity.
5. The flow gradient value was 10 or greater.
4. The flow gradient value was between 5 and 10.
3. The flow gradient value was 3 or greater and less than 5.
2. The flow gradient value was between 1 and 3.
1: The flow gradient value was less than 1.

(Evaluation of storage stability)
For each example and comparative example of ink composition, the viscosity was measured using an E-type viscometer (product name: RE100L viscometer, manufactured by Toki Sangyo Co., Ltd.) at a temperature of 25°C and a rotor rotation speed of 20 rpm. Afterward, the compositions were stored at 25°C for 30 days in a static state, and the viscosity at 25°C was measured again using the same method as before storage. Storage stability was evaluated by calculating the percentage change in viscosity before and after storage using the following formula.

Viscosity change rate (%) = ((Viscosity after storage - Viscosity before storage) / Viscosity before storage) × 100

5. The absolute value of the rate of change in viscosity was 3% or less.
3. The absolute value of the rate of change in viscosity was greater than 3% and less than or equal to 5%.
1. The absolute value of the rate of change in viscosity exceeded 5%.

(Evaluation of hardening properties)
0.1 mL of the ink composition for each example and comparative example was spread onto an OPP film using an RI color spreader (two-part roll, manufactured by Akira Seisakusho Co., Ltd.). Then, electron beam irradiation (EB irradiation device, irradiation conditions are as described in the "EB curing conditions" column of Tables 1 to 4) was repeated until the ink coating printed on the printed material hardened, and the number of passes was counted. Hardening was determined when the ink did not adhere when the coating was rubbed with a cotton swab.
It hardened with a 5:1 pass.
It hardened in a 4:2 pass.
It hardened in a 3:3 pass.
It hardened in a 2:4 pass.
1. Cured or did not cure after 5 or more passes.

(Evaluation of suitability for water width)
First, unless otherwise specified, the printed materials were produced by printing on printing paper according to the following procedures and conditions.
• Printing press: Komori Corporation, full-size single-sided four-color press • Print rotation speed: 12,000 sph
• Printing plate: Fujifilm Global Graphic Systems, XP-F (CTP plate) AM175 lines • Printing paper: Nippon Paper Industries, OK Coat L

Printing was started with the dampening water supply dial set to 30, and after printing 10,000 sheets, the dampening water supply dial was reduced to 15 (the amount of dampening water supplied was reduced). The ink stain density (OD value) in the blank areas (non-image areas) of the printed materials obtained when the dial value was reduced was measured, and the suitability of the water width was evaluated according to the following criteria.
5. The ink stain density in the plain areas was less than 0.01.
4. The ink stain density in the plain areas was 0.01 or higher and less than 0.05.
3. The ink stain density in the plain areas was 0.05 or higher and less than 0.1.
2. The ink stain density in the plain areas was between 0.1 and less than 0.2.
1. The ink stain density in the plain areas was 0.2 or higher.

(Evaluation of concentration stability)
Printed materials were prepared using the ink compositions of each example and comparative example under the same conditions as described in "(Evaluation of Water Width Suitability)" above. However, the dampening water supply amount was varied in 10% increments between 10% and 60% (increasing the dampening water supply amount), and the print density (OD value) of the image area of the printed material obtained at each dampening water supply amount was measured. The dampening water supply amount represents the rotation speed (%) of the water source roller. The rate of decrease in print density (OD value) was then calculated using the following formula with the X-Rite spectrophotometer "eXact Advance".

5. The rate of decrease in concentration was 0%.
4. The rate of decrease in concentration was greater than 0% and less than or equal to 5%.
3. The rate of decrease in concentration was greater than 5% but less than or equal to 10%.
2. The rate of decrease in concentration was greater than 10% but less than or equal to 15%.
1. The rate of decrease in concentration exceeded 15%.

(Odor evaluation)
0.1 mL of the ink composition for each example and comparative example was spread onto an OPP film using an RI color spreader (two-part roll, manufactured by Meisei Seisakusho Co., Ltd.). Then, the printed material was irradiated with an electron beam until the ink coating hardened, and the printed material was obtained. The electron beam irradiation conditions were the same for all cases except for the curability evaluation of Comparative Examples 14-16: acceleration voltage of 90 kV, irradiation dose of 30 kGy, and oxygen concentration of 100 ppm. In Comparative Examples 14-16, the curing conditions were also as described in the "EB curing conditions" in the table. Then, four panelists checked for the presence or absence of odor in the printed material using the OPP film as the substrate.
5. No one detected any odor.
4:1 person detected an odor.
3: Two people noticed the odor.
2:3 people noticed the odor.
1. Everyone noticed the odor.

(Evaluation of abrasion resistance)
In the printed material using the above-mentioned OPP film as a base material, friction was applied 200 times back and forth with a 500g weight via a backing cloth (Kanakin No. 3), and the condition of the coating after this friction was observed visually.
5. No scratches were observed on the surface of the cured film.
4. Although scratches were observed on the surface of the cured film, no peeling was confirmed.
3: Less than half of the entire surface of the hardened film peeled off, revealing less than half of the underlying material.
2: More than half of the entire surface of the hardened film peeled off, exposing more than half of the substrate.
1: The hardened film has completely peeled off.

(Preparation of cured products using films other than OPP as a base material)
0.1 mL of the ink composition for each example and comparative example was spread onto each film (PE, OPA, PET) other than OPP using an RI color spreader (two-roll type, manufactured by Meisei Seisakusho Co., Ltd.). Then, electron beam irradiation was performed until the ink coating printed on the material hardened, and the printed material was obtained. The electron beam irradiation conditions were the same for all cases except for the curability evaluation of comparative examples 14 to 16: acceleration voltage of 90 kV, irradiation dose of 30 kGy, and oxygen concentration of 100 ppm. In comparative examples 14 to 16, curing was also performed under the conditions described in "EB curing conditions" in the table.

(Tape adhesion)
Cellophane tape (manufactured by Nichiban Co., Ltd., product name "Sellotape®") was applied to the cured coating surface of printed materials using each of the above films (OPP, PE, OPA, PET) as a base material, and then peeled off in one swift motion. The area of the cured coating that was peeled off was evaluated on a five-point scale according to the following criteria. A smaller peeled area was considered to indicate better adhesion between the cured coating and the resin film.
5: It didn't peel off at all.
4. The amount of peeled hardened film was greater than 0% and less than or equal to 20% of the total area.
3. The amount of peeled hardened coating was between 20% and 50% of the total area.
2. The amount of peeled hardened coating was between 50% and 75% of the total area.
1. The peeled-off hardened coating covered more than 75% of the surface area.

(Lamination suitability)
First, adhesive (Mitsui Chemicals, "Takelac A969V/Takenate A-5") was applied to the cured surface of printed materials using each of the above films (OPP, PE, OPA, PET) as a base material at a solid content of 3.5 g/ ^m² . Then, an unoriented polypropylene film (RM Tohcello, "GLC", 40 μm thick) was laminated using a dry laminating machine. Next, the tensile strength of each laminate was determined using a tensile testing machine (Yasuda Seiki Seisakusho) under the conditions of a measurement temperature of 25°C and a tensile speed of 200 mm/min. Finally, the lamination suitability was evaluated based on the following criteria.
5. The peel strength was 1.5 N/15 mm or higher.
4. The peel strength was 1.0 N/15 mm or more and less than 1.5 N/15 mm.
3. The peel strength was 0.5 N/15 mm or more and less than 1.0 N/15 mm.
2. The peel strength was 0.1 N/15 mm or more and less than 0.5 N/15 mm.
1. The peel strength was less than 0.1 N/15 mm.

The composition and evaluation results of the ink compositions for each example and comparative example are shown in Tables 1 to 4.

Based on the above, it has been confirmed that the method for manufacturing printed materials in this embodiment has excellent ink fluidity, storage stability, curability, water-to-weight compatibility, and concentration stability, as well as excellent odor suppression, abrasion resistance, tape adhesion, and lamination compatibility of the printed materials.

Claims (9)

An electron beam curable printing ink composition for offset printing, comprising: (A) a polymer of an allyl monomer represented by the following general formula (1); (B) a (meth)acrylate resin; (C) a polyfunctional (meth)acrylate; and (D) a pigment:
The aforementioned component (B) is at least one selected from the group consisting of epoxy (meth)acrylate resin, polyester (meth)acrylate resin, and urethane (meth)acrylate resin;
The aforementioned component (C) is at least one selected from the group consisting of ditrimethylolpropane tetra(meth)acrylate, tri(meth)acrylate of a trimethylolpropane adduct of 3 moles or more of ethylene oxide, tri(meth)acrylate of a trimethylolpropane adduct of 3 moles or more of propylene oxide, and tri(meth) acrylate of a glycerin adduct of 3 moles or more of propylene oxide;
An electron beam-curable printing ink composition having a viscosity of 1.0 Pa·s to 90.0 Pa·s as measured by a cone plate viscometer at 25°C and a shear rate of 100/s.
(In general formula (1), ^R1 and ^R2 each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X represents an n-valent group having a 4 to 8-membered anticyclic ring skeleton, and n is 2 or 3.) The electron beam curable printing ink composition according to claim 1, wherein component (C) is at least one selected from the group consisting of ditrimethylolpropanetetra(meth)acrylate, tri(meth)acrylate of a 3-mol ethylene oxide adduct of trimethylolpropane, tri(meth)acrylate of a 6-mol ethylene oxide adduct of trimethylolpropane, tri(meth)acrylate of a 3-mol propylene oxide adduct of trimethylolpropane, and tri(meth)acrylate of a 3-mol propylene oxide adduct of glycerin. The electron beam curable printing ink composition according to claim 1 or 2, wherein the content of component (A) in the electron beam curable printing ink composition is 3 to 30% by mass. The electron beam curable printing ink composition according to claim 1 or 2, wherein the content of component (A) in the electron beam curable printing ink composition is 15% by mass or less. The electron beam curable printing ink composition according to claim 1 or 2, wherein the content of component (B) in the electron beam curable printing ink composition is 5 to 60% by mass. The electron beam curable printing ink composition according to claim 1 or 2, wherein the content of component (C) in the electron beam curable printing ink composition is 5 to 60% by mass. The electron beam-curable printing ink composition according to claim 1 or 2, wherein the electron beam-curable printing ink composition is a surface-printing ink composition. The electron beam-curable printing ink composition according to claim 1 or 2, wherein the electron beam-curable printing ink composition is a reverse-printing ink composition. The electron beam curable printing ink composition according to claim 1 or 2, wherein the electron beam curable printing ink composition does not contain a polymerization initiator.