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

Abstract

To provide an active energy ray-curable offset printing ink which, even with an ozone-less metal halide lamp, a light-emitting diode, or a UV-LED lamp, combines superior curing performance with stability.SOLUTION: There are provided an active energy ray-curable offset printing ink satisfying (1) to (4), a printed material obtained by printing the ink, and a method for producing the printed material. (1) The ink contains 3 to 15 wt.% of a photopolymerization initiator which is an acylphosphine oxide compound having a number average molecular weight of 350 to 450 and a melting point of 120°C to 150°C, relative to the total amount of the ink. (2) The ink contains a photopolymerization initiator which is a dialkylaminobenzophenone compound, a photopolymerization initiator which is an α-aminoalkylphenone compound, or a photopolymerization initiator which is a thioxanthone compound. (3) The photopolymerization initiator of (2) is contained in an amount of 3 to 12 wt.% relative to the total amount of the ink. (4) The ink contains a compound having an ethylenic double bond.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an actinic radiation-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. [Background technology]

[0002] Active energy beam-curable inks are solvent-free and instantly cure and dry using active energy beams. Because they are environmentally friendly, offer excellent printability, and produce high-quality prints, they are 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, and stencil printing, as well as a combination of these methods (offset printing, in which the ink applied to the plate is transferred to an intermediate transfer material such as a blanket and then printed on the substrate). These inks are used for a variety of printed materials, including forms, various books, various packaging materials such as carton paper, various plastics, stickers and labels, fine art prints, and metal prints (fine art prints, beverage can prints, canned food prints, etc.). Active energy beam-curable offset printing inks, which combine lithographic printing with offset printing, are particularly popular in a variety of fields, including book printing, fine art prints, sticker and label printing, business form printing, and packaging printing for toys, paper cartons, and other food packaging.

[0003] In recent years, various types of light sources have been used for actinic ray-curable inks, including conventional light sources such as high-pressure mercury lamps and metal halide lamps, as well 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 diode UV-LEDs that emit ultraviolet light with a peak emission wavelength in the range of 350 to 420 nm. Inventions have been made that combine multiple photopolymerization initiators with different absorption wavelengths that are suited to the wavelength ranges of various light sources (see Patent Documents 1 to 3). However, it cannot be said that the ink itself has sufficient stability over time while still achieving sufficient curability under all light sources. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2009 / 008226 publication [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-94117 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-214782 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims 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-free metal halide lamps that do not generate ozone, light-emitting diodes, and UV-LED lamps, and further aims to provide a printed material using the ink and a method for producing the printed material. [Means for solving the problem]

[0006] As a result of intensive research into 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 a photopolymerization initiator that is an acylphosphine oxide compound having a high melting point, a compound selected from three specific photopolymerization initiators, and a compound having an ethylenic double bond in combination, and have thus completed the present invention.

[0007] That is, the present invention provides an actinic ray-curable offset printing ink that satisfies the requirements (1) to (4). (1) The ink contains 3 to 15% by weight of a photopolymerization initiator, which is an acylphosphine oxide compound having a number average molecular weight of 350 to 450 and a melting point of 120°C to 150°C. (2) Contains a photopolymerization initiator that is a dialkylaminobenzophenone compound, a photopolymerization initiator that is an α-aminoalkylphenone compound, or a photopolymerization initiator that is a thioxanthone compound. (3) The photopolymerization initiator (2) is contained in an amount of 3 to 12% by weight based on the total amount of the ink. (4) Contains a compound having an ethylenic double bond.

[0008] The present invention also provides the above-described actinic ray-curable offset printing ink, wherein the acylphosphine oxide compound is bis-(4-methylphenyl)-2,4,6-trimethylbenzoylphosphine oxide or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0009] The present invention also provides the actinic ray-curable offset printing ink described above, wherein the dialkylaminobenzophenone compound is 4,4'-bis-(dimethylamino)benzophenone or 4,4'-bis-(diethylamino)benzophenone.

[0010] 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-phenyl)-1-butanone, 1-(biphenyl-4-yl)-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.

[0011] The present invention also provides the above-described actinic ray-curable offset printing ink, wherein the compound having an ethylenic double bond is a compound having two or more ethylenic double bonds.

[0012] The present invention also provides a printed matter obtained by printing with the above-described active energy ray-curable offset printing ink.

[0013] 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. [Effects of the Invention]

[0014] 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. DETAILED DESCRIPTION OF THE INVENTION

[0015] The active energy ray-curable offset printing ink of the present invention satisfies (1) to (4) to achieve the intended effects of the present invention. An active energy ray curable offset printing ink characterized by: (1) The ink contains 3 to 15% by weight of a photopolymerization initiator, which is an acylphosphine oxide compound having a number average molecular weight of 350 to 450 and a melting point of 120°C to 150°C. (2) Contains a photopolymerization initiator that is a dialkylaminobenzophenone compound, a photopolymerization initiator that is an α-aminoalkylphenone compound, or a photopolymerization initiator that is a thioxanthone compound. (3) The photopolymerization initiator (2) is contained in an amount of 3 to 12% by weight based on the total amount of the ink. (4) Contains a compound having an ethylenic double bond.

[0016] (Acylphosphine oxide compounds) The acylphosphine oxide compound used in the present invention has a number average molecular weight of 350 to 450 and a melting point of 120°C to 150°C. Specific examples include 2,4,6-trimethylbenzoylphosphines such as bis-(4-methylphenyl)-2,4,6-trimethylbenzoylphosphine oxide (Mn = 376.4, melting point 127°C) and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Mn = 418.5, melting point 130 to 131°C). The acylphosphine oxide compounds may be used alone or in combination of two or more.

[0017] (Dialkylaminobenzophenone compounds) Specific examples of the dialkylaminobenzophenone compound used in the present invention include 4,4'-dialkylaminobenzophenones such as 4,4'-bis-(dimethylamino)benzophenone, 4,4'-bis-(diethylamino)benzophenone, etc. The dialkylaminobenzophenone compounds may be used alone or in combination of two or more.

[0018] (thioxanthone compounds) 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.

[0019] (α-aminoalkylphenone compounds) The α-aminoalkylphenone compounds 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-mercaptophenyl)-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-morph Examples include 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, etc. 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 are preferred.

[0020] The content of the photopolymerization initiator, which is an acylphosphine oxide compound, is preferably in the range of 3 to 15% by mass of the total amount of the ink of the present invention. In particular, if it is 3% by mass or more, good fluidity can be obtained, and if it is 15% by mass or less, good curability and improved storage stability can be expected. A content in the range of 4 to 12% by mass is even more preferable. The content of the photopolymerization initiator, which is the dialkylaminobenzophenone compound, is preferably in the range of 3 to 10% by mass of the total amount of the ink of the present invention. In particular, if it is 3% by mass or more, good curability can be obtained, and if it is 10% by mass or less, improved storage stability can be expected. Among these, the content is more preferably in the range of 3 to 8% by mass. The content of the photopolymerization initiator, which is the thioxanthone compound, is preferably in the range of 0.1 to 6% by mass of the total amount of the ink of the present invention. In particular, if it is 1% by mass or more, good curability can be obtained, and if it is 5% by mass or less, improved fluidity can be expected. Of these, the content is more preferably in the range of 2 to 4% by mass. The content of the photopolymerization initiator, which is an α-aminoalkylphenone compound, is preferably in the range of 2 to 12% by mass of the total amount of each ink. In particular, if it is 3% by mass or more, good curability can be obtained, and if it is 9% by mass or less, improved storage stability can be expected. Of these, the content is more preferably in the range of 3 to 8% by mass.

[0021] (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 benzophenone compounds, ketocoumarin compounds, hydroxyacetophenone compounds, and / or benzyl dimethyl ketal compounds.

[0022] (benzophenone compounds) Benzophenone compounds used in the present invention include 4,4'-dialkylaminobenzophenones such as 4,4'-bis-(dimethylamino)benzophenone and 4,4'-bis-(diethylamino)benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 4-methylbenzophenone. Among these, 4,4'-bis-(diethylamino)benzophenone is preferred from the standpoint of safety. These benzophenone compounds may be used alone or in combination of two or more.

[0023] (Ketocoumarin compounds) 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.

[0024] (Hydroxyacetophenone compounds) Examples of the hydroxyacetophenone compound used in the present invention include ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxycyclohexyl 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.

[0025] (Benzyl dimethyl ketal compound) The benzyl dimethyl ketal compound used in the present invention includes, for example, 2,2-dimethoxy-2-phenylacetophenone (Omnirad651, manufactured by IGM Resins BV).

[0026] 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.

[0027] In the present invention, the total amount of photopolymerization initiators is preferably in the range of 6 to 27 mass % of the total amount of the ink of the present invention, more preferably in the range of 7 to 20 mass %, and most preferably in the range of 8 to 18 mass %.

[0028] Furthermore, the active energy ray-curable offset printing ink of the present invention must contain (4) a compound having an ethylenic double bond.

[0029] Examples of the compound having an ethylenic double bond include a (meth)acrylic group-containing compound and an additive. Examples of the monofunctional monomer that is a (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. Examples of the acrylates include 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, and dicyclopentenyloxyethyl (meth)acrylate.

[0030] 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, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, di(meth)acrylate of tris(2-hydroxyethyl)isocyanurate, and mixtures of 1 mole of neopentyl glycol with 4 moles or more 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, 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.

[0031] 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.

[0032] The total amount of the compounds 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.

[0033] Furthermore, the active energy ray-curable offset printing ink of the present invention may contain a body pigment. Inorganic fine particles can be used as the body pigment. Examples of inorganic fine particles include inorganic coloring pigments such as titanium oxide, graphite, and zinc oxide; inorganic 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 adjust the fluidity of the ink, prevent misting, and prevent penetration into printing substrates such as paper, but also suppress peeling, which can occur during printing at low temperatures such as winter or high-speed printing. In particular, when the substrate is a paper material, talc, magnesium carbonate, and silica are preferred from the viewpoint of being able to suppress "paper peeling," and talc and magnesium carbonate are particularly preferred from the viewpoint of being able to maintain the fluidity of the composition.

[0034] 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.

[0035] 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.

[0036] 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 actinic energy ray-curable ink of the present invention, in order to obtain a good effect of improving curability.

[0037] The active energy ray-curable offset printing ink of the present invention may further contain stabilizers, polymerization inhibitors, silicon-based additives, waxes, pigments, dyes, etc., as required.

[0038] 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. 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.

[0039] 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 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% by mass to 1% by mass of the total ink of the present invention.

[0040] Wax can be added to the active energy ray-curable offset printing ink of the present invention to improve curability. Examples of wax 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 acid and soybean oil fatty acid. The amount of wax 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.

[0041] 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.

[0042] Examples of the inorganic pigment include iron oxide and carbon black produced by known methods such as the contact method, furnace method, and thermal method. Examples include Raven 14, Raven 450, Raven 860 Ultra, Raven 1035, Raven 1040, Raven 1060 Ultra, Raven 1080 Ultra, Raven 1180, Raven 1255 (all manufactured by Birla), Regal 250R, Regal 400R, Regal 330R, Regal 660R, Mogul L (all manufactured by Cabot Corporation), MA7, MA8, MA11 (all manufactured by Mitsubishi Chemical Corporation), and the like. These may be used alone or in appropriate combination of two or more.

[0043] 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.

[0044] Specific examples of pigments used in yellow inks include CI 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.

[0045] Specific examples of pigments used in magenta inks include CI 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 CI Pigment Violet 19, etc.

[0046] Specific examples of pigments used in cyan inks include CI Pigment Blue 1, 2, 3, 15, 15:3, 15:4, 16, 22, 60, 63, 66, and the like.

[0047] 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.

[0048] (resin) As the resin, various known and commonly used binder resins can be used. The term "binder resin" used herein refers to any resin that has appropriate pigment affinity and dispersibility and the rheological properties required for printing inks. Examples of 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 that have at least one polymerizable group in the molecule. These binder resins may be used alone or in combination of two or more.

[0049] 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 suppressing misting and paper 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.

[0050] 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.

[0051] 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.

[0052] 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).

[0053] 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.

[0054] The printing substrate to be used with the active energy ray-curable offset printing ink of the present invention is not particularly limited, and can be used, for example, for printing catalogs, posters, flyers, CD jackets, direct mail, pamphlets, and packaging for cosmetics, beverages, pharmaceuticals, toys, equipment, and the like, as well as various synthetic papers and the like. In addition, the ink can be used on films or sheets of polyester resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl alcohol, polyethylene, polypropylene, polyacrylonitrile, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid copolymer, nylon, polylactic acid, polycarbonate, and the like, cellophane, aluminum foil, and various other substrates that have conventionally been used as printing substrates. It may also be used on other substrates such as metal substrates, glass substrates, paper substrates, wood substrates, and fibrous substrates.

[0055] 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. [Example]

[0056] The present invention will be specifically described below with reference to examples and comparative examples. Hereinafter, "parts" and "%" are all based on mass.

[0057] [DAP-A Varnish Manufacturing Method] Diallyl phthalate resin (Daiso DAP A, manufactured by Osaka Soda Co., Ltd.) solid content 33.33 mass % and MIRAMER M600 dipentaerythritol hexaacrylate (CAS 126-58-9, manufactured by MIWON Co., Ltd.) 66.67 mass % were thoroughly dissolved and stirred at 90°C to prepare DAP-A varnish.

[0058] [Method for manufacturing active energy ray curable offset printing ink] The active energy ray-curable offset printing inks of Examples 1 to 8 and Comparative Examples 1 to 6 were milled in a three-roll mill according to the formulations shown in Tables 1 and 2. Note that blank spaces in the tables indicate that the ink was not blended, and the values in the tables are in mass %.

[0059] (Drying method using ultraviolet light-emitting diode light source) Using a UV irradiation device (manufactured by Eye Graphics) equipped with a water-cooled UV-LED (central emission wavelength 385nm ± 5nm, UV-LED output 100%) and a belt conveyor, the developed material was placed on the conveyor and passed directly under the LED (irradiation distance 9cm) at a conveyor speed of 100m / min. The developed material after applying the photocurable ink obtained by the above method was irradiated with ultraviolet (UV) light to cure and dry the ink film.

[0060] (Evaluation item 1: Curability of active energy ray-curable ink) Immediately after curing, the cured ink layer was rubbed with a fingernail to evaluate the curability of the cured film. The evaluation criteria were as follows: ◎: No scratches are left even when rubbed with strong force, and UV curing properties are very good. Good: If you rub it hard, it will be slightly scratched. △: Scratches are clearly visible when rubbed with strong force ×: Scratches were clearly visible even when rubbed with a weak force, and the UV curing properties were poor.

[0061] (Evaluation item 2: Liquidity) Ink fluidity was measured using the spreadmeter method (parallel plate viscometer) in accordance with JIS K5101, 5701. The ink was sandwiched between two horizontally placed parallel plates, and the concentric spreading of the ink due to the weight of the loaded plates (115 grams) was observed over time. 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-point scale. In this evaluation item, compositions with a DM of less than 30 mm are prone to printability problems such as ink fountain breakage on the printing press and poor ink transfer between the ink rollers. (Evaluation criteria) 5: 40mm 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 25mm

[0062] (Evaluation item 3: Stability) 40 g of each of the indigo inks from Examples 1 to 8 and Comparative Examples 1 to 6 was placed in a 50 mL metal can, the lid was put on, 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, the presence of any insoluble gel on the wire mesh was visually confirmed. ○: No gel was observed on the wire mesh. ×: Gel was observed on the wire mesh.

[0063] The formulations and evaluation results of each active energy ray-curable offset printing ink are shown in Tables 1 and 2. Note that blank spaces indicate no formulation.

[0064] · [Table 1]

[0065] · [Table 2]

[0066] The abbreviations in the table are as follows: FASTOGEN BLUE FA5375: Pigment Blue 15:3 indigo pigment (DIC Corporation) Neolite SA300: (Takehara Chemical Industry Co., Ltd.) High Filler 5000PJ: (Matsumura Sangyo Co., Ltd.) S-381-N1: Polyethylene wax (manufactured by Shamrock) Miramer M600: Dipentaerythritol hexaacrylate (Miwon) SR355NS: Ditrimethylolpropanetetraacrylate (manufactured by Sartomer) Miramer M240: Bisphenol A, Ethylenediamine diacrylate Miramer M3130: Ethylene oxide modified (3 mol) trimethylolpropane triacrylate (Miwon) TMO: Bis-(4-methylphenyl)-2,4,6-trimethylbenzoyl-phosphine oxide (Shanghai Yinzhu Industrial Co., Ltd.) Omnirad 819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (IGM Resins BV) Omnirad EMK: 4,4'-bis-(diethylamino)benzophenone (manufactured by IGM Resins BV) Omnirad 379: 2-dimethylamino-2-(4-methyl-benzoyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (IGM Resins BV) RUNTECURE 1607: 1-(4-methoxyphenyl)-2-methyl-2-morpholin-4-yl-propan-1-one (Tianjin Jiuri New Materials Co., Ltd.) Omnirad 907: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (IGM Resins BV) Omnirad DETX: 2,4-diethyl-9H-thioxanthen-9-one (manufactured by IGM Resins BV) SpeedCure 2-ITX: 2-isopropylthioxanthone (ARKEMA KK) Omnirad TPO-L: Ethyl phenyl (2,4,6-trimethylbenzoyl) phosphinate (manufactured by IGM Resins BV) Omnirad 4MBZ: 4-methylbenzophenone (manufactured by IGM Resins BV) Omnirad 651: 2,2-dimethoxy-2-phenylacetophenone (IGM Resins BV) Suncerer TT-CU: Copper dimethyldithiocarbamate (manufactured by Sanshin Chemical Industry Co., Ltd.) Q-1301: n-Nitrosophenylhydroxylamine aluminum salt (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0067] It is clear that the active energy ray-curable lithographic offset printing inks of Examples 1 to 8 have excellent curability, fluidity, and stability, whereas the inks of Comparative Examples 1 to 6 are inferior in either curability, fluidity, or stability.

Claims

1. An active energy ray-curable offset printing ink that satisfies (1) to (4). (1) The ink contains a photopolymerization initiator, which is an acylphosphine oxide compound having a number average molecular weight of 350 to 450 and a melting point of 120°C to 150°C, in an amount of 3 to 15% by weight based on the total weight of the ink. (2) The composition contains a photopolymerization initiator which is a dialkylaminobenzophenone compound, a photopolymerization initiator which is an α-aminoalkylphenone compound, or a photopolymerization initiator which is a thioxanthone compound. (3) The photopolymerization initiator (2) is contained in an amount of 3 to 12% by weight based on the total amount of the ink. (4) Contains a compound having an ethylenic double bond.

2. 2. The active energy ray-curable offset printing ink according to claim 1, wherein the acylphosphine oxide compound is bis-(4-methylphenyl)-2,4,6-trimethylbenzoylphosphine oxide or bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

3. 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.

4. 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.

5. 2. 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 the actinic energy ray-curable offset printing ink according to any one of claims 1 to 5 onto a substrate, and curing the printed ink with actinic energy rays.

Images