Active energy ray-curable offset printing ink, printed matter using same, and printed matter manufacturing method

Abstract

The present invention pertains to: an active energy ray-curable offset printing ink characterized by comprising (1) 3-9 wt% of a photopolymerization initiator that is a dialkylaminobenzophenone compound, (2) 2-5 wt% of a photopolymerization initiator that is a thioxanthone compound, (3) 3-8 wt% of a photopolymerization initiator that is an α-aminoalkylphenone compound, and (4) a compound having an ethylenic double bond; printed matter obtained through printing with said printing ink; and a printed matter manufacturing method. The dialkylaminobenzophenone compound is preferably 4,4'-bis-(dimethylamino)benzophenone or 4,4'-bis-(diethylamino)benzophenone.

Description

Active energy ray curable offset printing ink, printed matter using the same, and method for producing printed matter

[0001] The present invention relates to an actinic ray-curable offset printing ink that exhibits excellent curability and stability even when used with an ozone-free ultraviolet irradiation device that uses a light source that incorporates an ozone-cutting or infrared filter, such as a metal halide lamp, high-pressure mercury lamp, or electrodeless metal halide lamp, or an ultraviolet irradiation device that uses a light-emitting diode or UV-LED lamp. The present invention also relates to a printed material using the ink, and a method for producing the printed material.

[0002] 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 printed materials. They are therefore used in a variety of printing methods, including lithographic printing (including lithographic printing using dampening water and waterless lithographic printing without dampening water), letterpress printing, intaglio printing, stencil printing, and a combination of these printing methods, including a transfer (offset) method in which the ink applied to the printing plate is transferred to an intermediate transfer medium such as a blanket and then printed on a substrate. They are applied to a variety of printed materials, including printed materials for forms, various book prints, various packaging prints such as carton paper, various plastic prints, prints for stickers and labels, fine art prints, and metal prints (art prints, prints on beverage cans, prints on canned food, etc.). Active energy ray-curable offset printing inks, which combine lithographic printing with the offset method, are particularly widely used in fields such as various book prints, fine art prints, sticker and label prints, business form prints, and package prints for food packaging such as toys and paper cartons. In addition to conventional light sources such as high-pressure mercury lamps and metal halide lamps, various types of light sources have been used in recent years for actinic ray-curable inks, such as light sources that use ozone-free metal halide lamps that do not generate ozone and emit ultraviolet light in the range of 230 to 420 nm, and light-emitting diodes (UV-LEDs) that emit ultraviolet light with a peak emission wavelength in the range of 350 to 420 nm, and inventions have been made that combine multiple photopolymerization initiators with different absorption wavelengths that are tailored to the wavelength ranges of various light sources (Patent Documents 1 to 3). However, at present, it cannot be said that sufficient curing properties can be obtained with all light sources while maintaining the stability of the ink itself over time.

[0003] Patent Document 1: WO2009 / 008226 Patent Document 2: JP2011-94117 Patent Document 3: JP2012-214782

[0004] An object of the present invention is to provide an actinic ray-curable offset printing ink that exhibits excellent curability and stability not only with conventional metal halide lamps and high-pressure mercury lamps, but also with ozone-less metal halide lamps that do not generate ozone, light-emitting diodes, and UV-LED lamps, and further to provide a printed material using the ink and a method for producing the printed material.

[0005] As a result of extensive research aimed at solving the above problems, the present inventors have found that an actinic ray-curable offset printing ink that combines excellent curability and stability can be obtained by using three specific types of photopolymerization initiators in combination with a compound having an ethylenic double bond, and have thus completed the present invention.

[0006] That is, the present invention provides an actinic ray-curable offset printing ink containing (1) 3 to 9 wt % of a photopolymerization initiator that is a dialkylaminobenzophenone compound, (2) 2 to 5 wt % of a photopolymerization initiator that is a thioxanthone compound, (3) 3 to 8 wt % of a photopolymerization initiator that is an α-aminoalkylphenone compound, and (4) a compound having an ethylenic double bond.

[0007] The present invention also provides the actinic ray-curable offset printing ink as described above, wherein the dialkylaminobenzophenone compound is 4,4'-bis-(dimethylamino)benzophenone or 4,4'-bis-(diethylamino)benzophenone.

[0008] The present invention also relates to a compound, wherein the α-aminoalkylphenone compound is 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-piperidinyl) and the active energy ray-curable offset printing ink as described above, wherein the active energy ray-curable offset printing ink is selected from the group consisting of 1-(4-methoxyphenyl)-2-methyl-2-morpholinopropan-1-one, 1-(4-methoxyphenyl)-2-methyl-2-morpholin-4-yl-propan-1-one, and polyethylene glycol (200) di(β-4[4-(2-dimethylamino-2-benzyl)butanonylphenyl]piperazine propionate.

[0009] The present invention also provides the above-described actinic ray-curable offset printing ink, which contains an acylphosphine oxide compound, a benzophenone compound, a ketocoumarin compound, a hydroxyacetophenone compound, and / or a benzyl dimethyl ketal compound.

[0010] The present invention also provides the actinic ray-curable offset printing ink described above, wherein the compound having an ethylenic double bond is a compound having two or more ethylenic double bonds.

[0011] The present invention also provides a printed matter obtained by printing with the above-described active energy ray-curable offset printing ink.

[0012] The present invention also provides a method for producing a printed matter, comprising the steps of printing the above-described actinic energy ray-curable offset printing ink on a substrate, and curing the printed ink with actinic energy rays.

[0013] The present invention provides an actinic ray-curable offset printing ink that exhibits excellent curability and stability not only with conventional metal halide lamps and high-pressure mercury lamps, but also with ozone-free metal halide lamps that do not generate ozone, light-emitting diodes, and UV-LED lamps. Furthermore, it also provides a printed material using the ink and a method for producing the printed material.

[0014] The active energy ray-curable offset printing ink of the present invention exhibits the intended effects of the present invention by containing: (1) a photopolymerization initiator that is a dialkylaminobenzophenone compound; (2) a photopolymerization initiator that is a thioxanthone compound; (3) a photopolymerization initiator that is an α-aminoalkylphenone compound; and (4) a compound having an ethylenic double bond.

[0015] (Dialkylaminobenzophenone Compound) Specific examples of the dialkylaminobenzophenone compound used in the present invention include 4,4'-dialkylaminobenzophenones such as 4,4'-bis-(dimethylamino)benzophenone and 4,4'-bis-(diethylamino)benzophenone. The dialkylaminobenzophenone compounds may be used alone or in combination of two or more.

[0016] (Thioxanthone Compound) Examples of the thioxanthone compound used in the present invention include 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-diisopropylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dichlorothioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthone-2-yloxy-N,N,N-trimethyl-1-propanamine hydrochloride, and the like. Preferred are 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, and 2,4-dichlorothioxanthone. , 1-chloro-4-propoxythioxanthone, 2-chlorothioxanthone, and 2-isopropylthioxanthone. These thioxanthone compounds may be used alone or in combination of two or more.

[0017] (α-Aminoalkylphenone compound) Examples of the α-aminoalkylphenone compound used in the present invention include 2-(dimethylamino)-2-methyl-1-[4-(4-morpholinyl)phenyl]-3-phenyl-1-propanone, 1-butanone, 2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-2-(phenylmethyl)-,(2S)-, 2-(dimethylamino)-2-methyl-3-(4-methylphenyl)-1-[4-(4-morpholinyl)phenyl]-1-propanone, 2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]- ]-2-(phenylmethyl)-1-pentanone, 2-(dimethylamino)-2-[(4-ethylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-(dimethylamino)-2-[(4-hydroxyphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-[(4-butylphenyl)methyl]-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 1-butanone, 2-(dimethylamino)-1-[4-(4-morpholinyl) phenyl]-2-[(4-propylphenyl)methyl]-, 2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-2-phenyl-1-butanone, 3-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-3-(phenylmethyl)-2-pentanone, 2-(dimethylamino)-2-ethyl-1-[4-(4-morpholinyl)phenyl]-4-phenyl-1-butanone, 3-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-3-phenyl-2-butanone, 1-(4-mercaptomethyl)- 1-[4-(ethylthio)phenyl]-2-methyl-2-(4-morpholinyl)-1-propanone, 1-[4-(ethylthio)phenyl]-2-methyl-2-(4-morpholinyl)-1-propanone, dimethyl[4-[2-methyl-2-(4-morpholinyl)-1-oxopropyl]phenyl]sulfonium, 2-methyl-1-[4-[(1-methylethyl)thio]phenyl]-2-(4-morpholinyl)-1-propanone, ethylmethyl[4-[2-methyl-2-(4-morpholinyl)-1-oxopropyl]phenyl]sulfonium,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-piperidinylphenyl)-1-butanone, 1-(biphenyl-4-yl)-2-methyl-2-morpholinopropan-1-one, 1-(4-methoxyphenyl)-2-methyl-2-morpholin-4-yl-propan-1-one, polyethylene glycol (200) di(β-4[4-(2-dimethylamino-2-benzyl)butanonylphenyl]piperazinepropionate, and the like. In particular, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-piperidinylphenyl)-1-butanone, 1-(biphenyl-4-yl)-2-methyl-2-morpholinopropan-1-one, 1-(4-methoxyphenyl)-2-methyl-2-morpholin-4-yl-propan-1-one, polyethylene glycol (200) di(β-4[4-(2-dimethylamino-2-benzyl)butanonylphenyl]piperazinepropionate is preferred.

[0018] The content of the dialkylaminobenzophenone compound photopolymerization initiator is preferably in the range of 2 to 12% by mass of the total ink of the present invention. In particular, if it is 3% by mass or more, good curability can be obtained, and by keeping it to 10% by mass or less, improved storage stability can be expected. A content of 3 to 9% by mass is even more preferable. Furthermore, the content of the thioxanthone compound photopolymerization initiator is preferably in the range of 1 to 8% by mass of the total ink of the present invention. In particular, if it is 2% by mass or more, good curability can be obtained, and by keeping it to 6% by mass or less, improved fluidity can be expected. A content of 2 to 5% by mass is even more preferable. Furthermore, the content of the α-aminoalkylphenone compound photopolymerization initiator is preferably in the range of 2 to 12% by mass of the total ink of the present invention. In particular, if it is 3% by mass or more, good curability can be obtained, and by keeping it to 9% by mass or less, improved storage stability can be expected. A content of 3 to 8% by mass is even more preferable.

[0019] The ratio of the photopolymerization initiator which is a dialkylaminobenzophenone compound, the photopolymerization initiator which is a thioxanthone compound, and the photopolymerization initiator which is an α-aminoalkylphenone compound is preferably in the range of 1:1:1 to 3:1:3, and more preferably 1:1:1 to 2:1:3.

[0020] (Photopolymerization initiators that can be used in combination) In the present invention, photopolymerization initiators having structures other than the above-mentioned photopolymerization initiators can also be used in combination, such as acylphosphine oxide compounds, benzophenone compounds, ketocoumarin compounds, hydroxyacetophenone compounds, and / or benzyl dimethyl ketal compounds.

[0021] (Acylphosphine oxide compound) The acylphosphine oxide compound used in the present invention is preferably a compound represented by general formula (1).

[0022]

[0023] In general formula (1), Y １ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a structural moiety represented by general formula (2), Y​２ represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a (poly)alkoxyalkyl group having 1 to 6 carbon atoms (the alkoxyalkyl group portion is an alkoxyalkyl group having 2 to 12 carbon atoms), a phenyl group, or a structural moiety represented by general formula (3), and Y ３ represents a phenyl group or a group represented by general formula (2),

[0024]

[0025]

[0026] In general formula (3), Y １１ represents Y in general formula (1). １ and each independently represent the same group, and Y in general formula (3) ３３ represents Y in general formula (1). ３ and each independently represent the same group, and R in general formula (3) １４ , R １５ each independently represents an alkylene group having 1 to 6 carbon atoms or a (poly)oxyalkylene group having 1 to 6 carbon atoms, and R in general formula (1), general formula (2), and general formula (3) １ ~R １３ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0027] Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, etc. Specific examples of the alkylene group having 1 to 6 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group, etc.

[0028] In particular, in the general formula (1), R １ and R ２ and R ４ is a methyl group, R ３ and Y １ is hydrogen, Y ２ is an ethyl group, Y ３ is a phenyl group, ethylphenyl(2,4,6-trimethylbenzoyl)phosphinate is preferred, and an example of a commercially available product is TPO-L (#CAS 84434-11-7, manufactured by SARTOMER).

[0029] In addition, in the general formula (1), R １ and R ２ and R ４ is a methyl group, R ３ is a hydrogen atom, Y ２ is a polyalkoxymethyl group having 2 carbon atoms, Y ３ is represented by the structural moiety represented by general formula (2), and R ６ and R ７ and R ９ is a methyl group and R ５ and R ８ is preferably hydrogen, and an example of a commercially available product is Omnirad 820 (manufactured by IGM Resins BV).

[0030] In addition, in the general formula (1), R １ and R ２ and R ４ is a methyl group, R ３ is a hydrogen atom, Y １ is represented by the structural moiety represented by general formula (2), and R ５ ~R ９ is a hydrogen atom, Y ２ is an ethyl group, Y ３ is a phenyl group, ethyl (3-benzoyl-2,4,6-trimethylbenzoyl) (phenyl) phosphinate is preferred, and an example of a commercially available product is SpeedCure XKm (#CAS 1539267-56-5, manufactured by SARTOMER).

[0031] In addition, in the general formula (1), R １ , R ２ , R ４ is a methyl group, R ３ , Y １ is a hydrogen atom, Y ３ is a phenyl group, Y2 is a group represented by general formula (3), and R １０ , R １１ , R １３ is a methyl group, R １２ and Y １１ is a hydrogen atom, Y ３３ is a phenyl group, R １４ and R １５is preferably a (poly)oxyalkylene group having 2 carbon atoms, and an example of a commercially available product thereof is Omnipol TP (#CAS 1834525-17-5, manufactured by IGM Resins B.V.) These acylphosphine oxide compounds may be used alone or in combination of two or more.

[0032] (Benzophenone Compound) Examples of the benzophenone compound used in the present invention include 4-benzoyl-4'-methyldiphenyl sulfide and 4-methylbenzophenone. Of these, 4-methylbenzophenone is preferred from the standpoint of safety. These benzophenone compounds may be used alone or in combination of two or more.

[0033] (Ketocoumarin Compound) Examples of the ketocoumarin compound used in the present invention include 3-benzoylcoumarin, 3-(4-methoxybenzoyl)coumarin, 3-benzoyl-7-methoxycoumarin, 3-(4-methoxybenzoyl)7-methoxy-3-coumarin, 3-acetyl-7-dimethylaminocoumarin, 3-benzoyl-7-dimethylaminocoumarin, 3,3'-coumarinoketone, 3,3'-bis(7-diethylaminocoumarin)ketone, etc. These ketocoumarin compounds may be used alone or in combination of two or more.

[0034] (Hydroxyacetophenone Compound) Examples of the hydroxyacetophenone compound used in the present invention include ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxy-cyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, etc. These hydroxyacetophenone compounds may be used alone or in combination of two or more.

[0035] (Benzyl Dimethyl Ketal Compound) The benzyl dimethyl ketal compound used in the present invention includes, for example, 2,2-dimethoxy-2-phenylacetophenone (Omnirad 651, manufactured by IGM Resins BV).

[0036] The content of these photopolymerization initiators that may be used in combination is preferably in the range of 2 to 10% by mass of the total amount of the ink of the present invention. If it is 2% by mass or more, curability can be obtained, and if it is 6% by mass or less, improved storage stability can be expected. Of these, the content is more preferably in the range of 2 to 6% by mass.

[0037] In the present invention, the total amount of photopolymerization initiators is preferably in the range of 2 to 25% by mass, more preferably in the range of 5 to 20% by mass, and most preferably in the range of 10 to 20% by mass, of the total amount of the ink of the present invention.

[0038] Furthermore, the active energy ray-curable offset printing ink of the present invention must contain (4) a compound having an ethylenic double bond.

[0039] Examples of the compound having an ethylenic double bond include (meth)acrylic group-containing compounds and additives. Examples of the monofunctional monomer that is the (meth)acrylic group-containing compound 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 phenoxydiethyl (meth)acrylate. ethylene 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.

[0040] Examples of difunctional or higher functional monomers include 1,4-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene Di(meth)acrylates of dihydric alcohols such as ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and di(meth)acrylates of tris(2-hydroxyethyl)isocyanurate, and mixtures of 4 moles or more of ethylene oxide or propylene oxide with 1 mole of neopentyl glycol di(meth)acrylates of diols obtained by addition of 1 mole of bisphenol A to 2 moles of ethylene oxide or propylene oxide; di(meth)acrylates of diols obtained by addition of 1 mole of bisphenol A to 2 moles of ethylene oxide or propylene oxide; poly(meth)acrylates of trihydric or higher polyhydric alcohols such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and poly(meth)acrylate of dipentaerythritol; Examples of the poly(meth)acrylate include poly(meth)acrylates of polyoxyalkylene polyols such as triol tri(meth)acrylate obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of serine, di- or tri(meth)acrylate of triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane, and di(meth)acrylate of diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of bisphenol A.

[0041] Furthermore, the (meth)acrylic group-containing compound may be a polymerizable oligomer, such as an amine-modified acrylate, an amine-modified polyether acrylate, an amine-modified epoxy acrylate, an amine-modified aliphatic acrylate, an amine-modified polyester acrylate, or an amino(meth)acrylate, a polyester(meth)acrylate, a polyether(meth)acrylate, a polyolefin(meth)acrylate, a polystyrene(meth)acrylate, an epoxy(meth)acrylate, or a urethane(meth)acrylate.

[0042] The total amount of the compound having an ethylenic double bond is preferably in the range of 10 to 60% by mass, more preferably 10 to 40% by mass, and even more preferably 10 to 25% by mass, of the total amount of the ink of the present invention. Furthermore, from the viewpoint of achieving both excellent curability and excellent fluidity due to the combined use of various compounds, the amounts of both added are preferably within this range.

[0043] Furthermore, the active energy ray-curable offset printing ink of the present invention may contain an extender pigment. Inorganic fine particles can be used as the extender pigment. Examples of inorganic fine particles include inorganic coloring pigments such as titanium oxide, graphite, and zinc oxide; inorganic extender pigments such as lime carbonate powder, precipitated calcium carbonate, 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 abrasive powder; and inorganic pigments such as silicone and glass beads. These inorganic fine particles not only have the effects of adjusting the fluidity of the ink, preventing misting, and preventing penetration into printing substrates such as paper, but also have the effect of suppressing peeling, which can occur during printing under low temperature conditions such as winter or during high-speed printing. Particularly when the substrate is paper, talc, magnesium carbonate, and silica are preferred from the viewpoint of suppressing peeling, and talc and magnesium carbonate are particularly preferred from the viewpoint of maintaining the fluidity of the composition.

[0044] The talc, magnesium carbonate, and silica 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% by mass of the total amount of the ink of the present invention, when magnesium carbonate is used, its content is preferably in the range of 1 to 10% by mass of the total amount of the ink of the present invention, and when silica is used, its content is preferably in the range of 0.1 to 5% by mass of the total amount of the ink of the present invention.

[0045] Furthermore, since the active energy ray-curable offset printing ink of the present invention can improve the curability of the cured coating film of the ink, a photosensitizer can be further added, if necessary, to improve the curability.

[0046] 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 of the total amount of the active energy ray-curable ink of the present invention, in order to obtain a good effect of improving curability.

[0047] The active energy ray-curable offset printing ink of the present invention may further contain stabilizers (also called polymerization inhibitors or antioxidants), silicon-based additives, waxes, pigments, dyes, etc., as required.

[0048] Examples of the stabilizer include hindered phenol antioxidants, hindered amine antioxidants, organic sulfur antioxidants, phosphate ester antioxidants, dialkyldithiocarbamic acid copper complexes, and nitrosamine compounds. These stabilizers can be used alone or in combination of two or more. Combinations of two or more types are particularly preferred. The amount of these stabilizers used is preferably in the range of 0.01% by mass to 0.3% by mass of the total amount of the ink of the present invention, in order to obtain a good effect of improving storage stability.

[0049] 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, as well as polydimethylsiloxanes having polyether-modified acrylic groups and polydimethylsiloxanes having polyester-modified acrylic groups. These silicon-based additives can be used alone or in combination of two or more. From the viewpoint of achieving both excellent smoothness and excellent abrasion resistance, the amount of these silicon-based additives used is preferably in the range of 0.05% to 1% by mass of the total ink of the present invention.

[0050] Waxes can be added to the active energy ray-curable offset printing ink of the present invention to improve curability. Examples of waxes include paraffin wax, carnauba wax, beeswax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, polytetrafluoroethylene wax, and amide wax, as well as fatty acids having approximately 8 to 18 carbon atoms, such as coconut oil fatty acids and soybean oil fatty acids. The amount of these waxes used is preferably in the range of 0.5 to 4% by mass of the total ink of the present invention, from the viewpoint of achieving both excellent curability and excellent abrasion resistance.

[0051] In the active energy ray-curable offset printing ink of the present invention, known and commonly used inorganic pigments and organic pigments can be used.

[0052] Examples of the inorganic pigment include iron oxide and carbon black produced by known methods such as a contact method, a furnace method, a thermal method, etc. Examples include Raven 14, Raven 450, Raven 860 Ultra, Raven 1035, Raven 1040, Raven 1060 Ultra, Raven 1080 Ultra, Raven 1180, and Raven 1255 (all manufactured by Birla), Regal 250R, Regal 400R, Regal 330R, Regal 660R, and Mogul L (all manufactured by Cabot Corporation), and MA7, MA8, and MA11 (all manufactured by Mitsubishi Chemical Corporation). These may be used alone or in appropriate combination of two or more.

[0053] Examples of the organic pigment 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.

[0054] 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.

[0055] 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.

[0056] 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, 66, and the like.

[0057] Further examples of dyes include azo dyes such as monoazo and disazo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoimine dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, perinone dyes, phthalocyanine dyes, triarylmethane dyes, etc. These dyes can be used alone or in combination of two or more.

[0058] (Resin) As the resin, various known and commonly used binder resins can be used. The binder resin described here refers to any resin that has appropriate pigment affinity and dispersibility and the rheological properties required for printing inks. For example, non-reactive resins include diallyl phthalate resins, epoxy resins, polyurethane resins, polyester resins, petroleum resins, rosin ester resins, poly(meth)acrylic acid esters, cellulose derivatives, vinyl chloride-vinyl acetate copolymers, polyamide resins, polyvinyl acetal resins, and butadiene-acrylonitrile copolymers. Also usable are epoxy acrylate compounds, urethane acrylate compounds, and polyester acrylate compounds having at least one polymerizable group in the molecule. These binder resins may be used alone or in combination of two or more.

[0059] The resin can be used as a varnish by mixing and dissolving it with a compound having an ethylenic double bond for the purpose of adjusting the viscosity and achieving appropriate dispersibility. From the viewpoint of simultaneously suppressing misting and peeling, the content of such a varnish is preferably in the range of 10 to 60% by mass, more preferably 15 to 50% by mass, of the total amount of the ink of the present invention.

[0060] The active energy ray-curable offset printing ink of the present invention can be printed on a substrate and then irradiated with active energy rays to form a cured coating film.

[0061] Examples of the active energy rays include ionizing radiation such as ultraviolet rays, electron beams, α rays, β rays, γ rays, etc. 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 a curing reaction by ultraviolet rays.

[0062] As a source of ultraviolet light, ultraviolet lamps are generally used from the viewpoints of practicality and economy, and 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, ultra-high-pressure mercury lamps, electrodeless lamps, carbon arc lamps, xenon lamps, gallium lamps, metal halide lamps, sunlight, and ultraviolet light-emitting diodes (UV-LEDs).

[0063] In particular, in the active energy ray-curable offset printing ink of the present invention, by appropriately using the photopolymerization initiators (1) to (3) and (4) a compound having an ethylenic double bond in combination, it is possible to maintain excellent curability, excellent surface curability, excellent internal curability, and excellent adhesion not only with conventional metal halide lamps and high-pressure mercury lamps, but also with ozone-less metal halide lamps that do not generate ozone, light-emitting diodes, and UV-LED lamps.

[0064] The printing substrate used with the active energy ray-curable offset printing ink of the present invention is not particularly limited, and can be used for printing, for example, catalogs, posters, flyers, CD jackets, direct mail, pamphlets, packaging for cosmetics, beverages, pharmaceuticals, toys, equipment, etc., including high-quality paper, coated paper, art paper, construction paper, tissue paper, and cardboard, as well as various synthetic papers, as well as films or sheets of polyester resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl alcohol, polyethylene, polypropylene, polyacrylonitrile, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer, nylon, polylactic acid, polycarbonate, etc., cellophane, aluminum foil, and various other substrates conventionally used as printing substrates. The ink can also be used on other substrates such as metal substrates, glass substrates, paper substrates, wood substrates, and fibrous substrates.

[0065] The actinic energy ray-curable offset printing ink described in the present invention is produced in the same manner as conventional actinic energy ray-curable offset printing inks, by blending the compound having an ethylenic double bond, a photopolymerization initiator, other additives, etc., stirring and mixing them in a mixer or the like, and grinding the mixture using a dispersing machine such as a three-roll mill or a bead mill.

[0066] The present invention will be specifically described below with reference to examples and comparative examples. Hereinafter, "parts" and "%" are all based on mass.

[0067] [Method of Producing DAP-A Varnish] 33.33% by mass of solids of diallyl phthalate resin (Daiso DAP A, manufactured by Osaka Soda Co., Ltd.) and 66.67% by mass of MIRAMER M600 dipentaerythritol hexaacrylate (CAS 126-58-9, manufactured by MIWON Co., Ltd.) were thoroughly dissolved and stirred at 90°C to prepare DAP-A varnish.

[0068] [Method for producing active energy ray-curable offset printing inks] Active energy ray-curable offset printing inks of Examples 1 to 14 and Comparative Examples 1 to 9 were milled in a three-roll mill according to the formulations shown in Tables 1 to 5, to obtain active energy ray-curable offset printing indigo inks. Note that blank spaces in the tables indicate that no formulation was used, and the values ​​in the tables are in mass %.

[0069] (Drying method using ultraviolet light-emitting diode light source) A UV irradiation device (manufactured by iGraphics Co., Ltd.) equipped with a water-cooled UV-LED (central emission wavelength 385 nm±5 nm, UV-LED output 100%) and a belt conveyor was used, and the drawn-down product was placed on the conveyor and passed directly under the LED (irradiation distance 9 cm) at a conveyor speed of 100 m / min. The drawn-down product after coating with the photocurable ink obtained by the above method was irradiated with ultraviolet (UV) light to cure and dry the ink film.

[0070] (Evaluation item 1: Evaluation of curability of active energy ray-curable ink) The curability of the cured film was evaluated by rubbing the cured ink layer with a fingernail immediately after curing. The evaluation criteria were as follows: ⊚: No scratches even when rubbed with strong force, UV curability is very good. ◯: Slight scratches when rubbed with strong force. Δ: Clear scratches when rubbed with strong force. ×: Clear scratches even when rubbed with weak force, UV curability is poor.

[0071] (Evaluation Item 2: Fluidity) Ink fluidity was measured using the spreadmeter method (parallel plate viscometer) in accordance with JIS K5101, 5701. The ink sandwiched between two horizontally placed parallel plates was observed over time for its characteristic of spreading concentrically due to the weight of the loaded plates (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 using the following five levels, which indicate good printability. In this evaluation item, compositions with a DM of less than 30 mm are prone to problems with printability, such as fountain runout on the printing press and poor transfer between ink rollers. (Evaluation Criteria) 5: 40 mm or more 4: 35 to less than 40 mm 3: 30 to less than 35 mm 2: 25 to less than 30 mm 1: Less than 25 mm

[0072] (Evaluation item 3: Stability) 40 g of each of the indigo inks of Examples 1 to 14 and Comparative Examples 1 to 9 was placed in a 50 mL metal can, the can was closed, and the can was stored in an oven at 60°C for one month. After one month, each ink was dissolved in tetrahydrofuran and filtered through a wire mesh. After filtration, it was visually confirmed whether or not there was any insoluble gel on the wire mesh. ◯: No gel was observed on the wire mesh. ×: Gel was observed on the wire mesh.

[0073] Tables 1 to 5 show the formulations of each active energy ray-curable offset printing ink and the evaluation results.

[0074] ・

[0075] ・

[0076] ・

[0077] ・

[0078] ・

[0079] The abbreviations in the table are as follows: FASTOGEN BLUE FA5375: Pigment Blue 15:3 indigo pigment (manufactured by DIC Corporation) S-381-N1: Polyethylene wax (manufactured by Shamrock) Miramer M600: Dipentaerythritol hexaacrylate (manufactured by Miwon) SR355NS: Ditrimethylolpropane tetraacrylate (manufactured by Sartomer) Miramer M240: Bisphenol AEO modified diacrylate Miramer M3130: Ethylene oxide modified (3 mol) trimethylolpropane triacrylate (manufactured by Miwon) Omnirad EMK: 4,4'-bis-(diethylamino)benzophenone (manufactured by IGM Resins B.V.) Omnirad DETX: 2,4-diethyl-9H-thioxanthen-9-one (manufactured by IGM Resins B.V.) SpeedCure 2-ITX: 2-isopropylthioxanthone (manufactured by ARKEMA K.K.) Omnirad 379: 2-dimethylamino-2-(4-methyl-benzoyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (manufactured by IGM Resins B.V.) RUNTECURE 1607: 1-(4-methoxyphenyl)-2-methyl-2-morpholin-4-yl-propan-1-one (manufactured by Tianjin Jiuri New Materials Co., Ltd.) Omnirad 907: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (manufactured by IGM Resins B.V.) Omnirad 320: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins B.V.) Omnirad TPO-L: ethylphenyl(2,4,6-trimethylbenzoyl)phosphinate (manufactured by IGM Resins B.V.) SpeedCure XKm: ethyl(3-benzoyl-2,4,6-(trimethylbenzoyl)(phenyl)phosphinate (manufactured by ARKEMA K.K.) Omnirad 4MBZ: 4-methylbenzophenone (IGM Resins B. V.・Omnirad 651:2,2-Dimethoxy-2-phenylacetophenone (manufactured by IGM Resins B.V.) Suncerer TT-CU: Copper dimethyldithiocarbamate (manufactured by Sanshin Chemical Industry Co., Ltd.) Q-1301: n-Nitrosophenylhydroxylamine aluminum salt (Fujifilm Wako Pure Chemical Industries Co., Ltd.),

[0080] It is clear that the active energy ray-curable lithographic offset printing inks of Examples 1 to 14 have excellent curability, fluidity, and stability. On the other hand, the inks of Comparative Examples 1 to 9 are inferior in either curability, fluidity, or stability.

Claims

1. An active energy ray curable offset printing ink comprising: (1) 3 to 9 weight percent of a photopolymerization initiator which is a dialkylaminobenzophenone compound; (2) 2 to 5 weight percent of a photopolymerization initiator which is a thioxanthone compound; (3) 3 to 8 weight percent of a photopolymerization initiator which is an α-aminoalkylphenone compound; and (4) a compound having an ethylenic double bond.

2. The active energy ray-curable offset printing ink according to claim 1, wherein the dialkylaminobenzophenone compound is 4,4'-bis-(dimethylamino)benzophenone or 4,4'-bis-(diethylamino)benzophenone.

3. The active energy ray curable offset printing ink according to claim 1, wherein the α-aminoalkylphenone compound is 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-piperidinylphenyl)-1-butanone, 1-(biphenyl-4-yl)-2-methyl-2-morpholinopropan-1-one, 1-(4-methoxyphenyl)-2-methyl-2-morpholin-4-yl-propan-1-one, or polyethylene glycol (200) di(β-4[4-(2-dimethylamino-2-benzyl)butanonylphenyl]piperazinepropionate.

4. The active energy ray-curable offset printing ink according to claim 1, which contains an acylphosphine oxide compound, a benzophenone compound, a ketocoumarin compound, a hydroxyacetophenone compound, and / or a benzyl dimethyl ketal compound.

5. The active energy ray-curable offset printing ink according to claim 1, wherein the compound having an ethylenic double bond is a compound having two or more ethylenic double bonds.

6. A printed matter obtained by printing with the active energy ray-curable offset printing ink according to any one of claims 1 to 5.

7. A method for producing a printed matter, comprising the steps of printing an active energy ray-curable offset printing ink according to any one of claims 1 to 5 onto a substrate, and curing the printed ink with active energy rays.

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