Active energy ray curing black ink, and printed materials

Abstract

To provide an active energy ray-curable black ink that has ink dispersibility, fluidity equal as acidic carbon black while using neutral carbon black, and can reduce contamination of halftone dots compared with the acidic carbon black, as well as, to provide printed matters therewith.SOLUTION: An active energy ray-curable black ink contains neutral carbon black, two or more resins including a diallyl isophthalate resin, a (meth)acrylate compound including a (meth)acrylate compound having three or more (meth)acryloyl groups in a molecule, and an extender pigment.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an active energy ray-curable ink for printing and a printed matter using the same.

Background Art

[0002] In recent years, the demand for active energy ray-curable inks has been expanding in place of oil-based inks. The factors include that active energy ray-curable inks have high-speed drying properties (high curability) important for high-speed printing and labor saving, and excellent coating film resistance such as solvent resistance, which is an important physical property of printed matters. On the other hand, the quality of printed matters equivalent to that of oil-based inks is required.

[0003] Also, in active energy ray-curable black inks, from the viewpoints of ink dispersibility and fluidity, the use of acidic carbon black is the mainstream in the selection of carbon black (see Patent Document 1). The factors include that acidic carbon black has acidic polar groups due to the oxidation treatment in the manufacturing process, and thus the dispersibility and fluidity in the ink are improved. However, since it has acidic polar groups, it is hydrophilic and the ink is likely to contain water, easily causing problems such as contamination of halftone dots in printing. In addition, there is also a problem that the manufacturing cost becomes high because of the oxidation treatment.

[0004] On the other hand, neutral carbon black does not undergo oxidation treatment, so the manufacturing cost can be kept low. Therefore, the use of neutral carbon black is the mainstream in oil-based inks (see Patent Document 2). It is possible to maintain ink dispersibility and fluidity by mixing with solvents or natural resins for neutral carbon black without polar groups. However, neutral carbon black has poor compatibility with (meth)acrylate compounds used in active energy ray-curable inks, and the ink dispersibility and fluidity are significantly reduced. Therefore, it is difficult to formulate an ink using neutral carbon black in active energy ray-curable inks.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-081264 [Patent Document 2] Japanese Patent Publication No. 2019-119749 [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide an activated energy ray-curable black ink that uses neutral carbon black while having ink dispersibility and fluidity equivalent to acidic carbon black, and that can reduce halftone dot staining compared to acidic carbon black, and to provide printed materials using the same. [Means for solving the problem]

[0007] The inventors of this invention have conducted extensive research to solve the above problems and have found that the above problems can be solved by the activated energy ray curable black ink and printed materials using the same, as described below, and have completed the present invention.

[0008] In other words, the present invention is an active energy ray curable black ink containing a colorant, two or more types of resin, a (meth)acrylate compound, and an extender pigment, The coloring agent contains carbon black pigment with a pH value of 7.0 to 8.5. The resin contains diallyl isophthalate resin at a concentration of 13-30% by mass of the total resin amount. An active energy ray curable black ink containing a (meth)acrylate compound that has three or more (meth)acryloyl groups in its molecule.

[0009] The present invention also relates to the above-mentioned active energy ray curable ink, wherein the resin comprises a diallyl orthophthalate resin.

[0010] The present invention also provides an active energy ray-curable ink composition for printing inks, wherein the resin contains a rosin-modified resin.

[0011] The present invention also provides an active energy ray-curable ink composition for printing inks, wherein the rosin-modified resin is a reaction product of an addition reaction product of rosin acids (A) and an α,β-unsaturated carboxylic acid or its acid anhydride (B) and a polyol (C).

[0012] The present invention also provides an active energy ray-curable ink composition for printing inks, wherein the total content of the resin is 8 to 20% by mass in the total amount of the ink.

[0013] The present invention also provides an active energy ray-curable ink composition for printing inks, wherein the extender pigment contains at least one selected from the group consisting of magnesium carbonate, calcium carbonate, and talc.

[0014] The present invention also provides an active energy ray-curable ink composition for printing inks, which further contains silica.

[0015] The present invention also provides a printed matter obtained by printing the active energy ray-curable ink composition for printing inks on a substrate and curing it with active energy rays.

Advantages of the Invention

[0016] According to the present invention, there are provided an active energy ray-curable ink composition for printing inks which has ink dispersibility and fluidity equivalent to those of an acidic carbon black even when using a neutral carbon black and can reduce the stain of halftone dots, and a printed matter using the same.

Best Mode for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist thereof. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass". In addition, in this specification, descriptions such as “(meth)acryloyl”, “(meth)acrylic acid”, “(meth)acrylate”, and “(meth)acryloyloxy” mean “acryloyl and / or methacryloyl”, “acrylic acid and / or methacrylic acid”, “acrylate and / or methacrylate”, and “acryloyloxy and / or methacryloyloxy”, respectively, unless otherwise specified. Also, “PO” represents “propylene oxide” and “EO” represents “ethylene oxide”.

[0018] <Active energy ray curable inkjet ink> The active energy ray curable inkjet ink (hereinafter also simply referred to as “ink”) of the present invention contains a colorant, a resin, a (meth)acrylate compound, and an extender pigment.

[0019] <Colorant> The ink of the present invention contains, as a colorant, a neutral carbon black pigment having a pH value of 7.0 to 8.5 (hereinafter also referred to as “neutral carbon black”).

[0020] Here, carbon black includes acidic carbon black having a surface treatment to give an acidic polar group on the carbon surface (the acidic carbon black in the present invention refers to those having a pH value of less than 7.0 for carbon black), and neutral carbon black (pH value 7.0 to 8.5) without surface treatment and having no polar group on the carbon surface. Acidic carbon black was developed for the purpose of improving the dispersibility and fluidity of active energy ray curable inkjet ink, and currently, it is the mainstream carbon black in active energy ray curable inkjet ink. On the other hand, neutral carbon black is the mainstream carbon black in oil-based ink because its production cost is low due to no surface treatment.

[0021] In the ink of the present invention, by being able to use neutral carbon black, the cost of the ink can be reduced and the soiling of halftone dots can be reduced.

[0022] The pH value of carbon black is the value measured by the glass electrode method for a mixture obtained by mixing 3 g of carbon black and 20 g of distilled water, boiling for 5 minutes, and then cooling to room temperature.

[0023] In the present invention, the content of the neutral carbon black pigment is preferably 14 to 18% by mass in the total amount of the ink. By setting the content of the neutral carbon black pigment to 14 to 18% by mass in the total amount of the ink, it is possible to achieve both printing suitability and physical properties (such as density) of the printed matter.

[0024] <Resin> The ink of the present invention contains two or more kinds including a diallyl isophthalate resin as a resin.

[0025] In the present invention, the total content of the resin is 8 to 20% by mass in the total amount of the ink, preferably 10 to 15% by mass, and more preferably 12 to 13% by mass. By containing 8 to 20% by mass of the total content of the resin in the total amount of the ink, the balance of the viscoelasticity and fluidity of the ink is maintained.

[0026] <Diallyl isophthalate resin> The present invention includes a diallyl isophthalate resin as a resin. By including the diallyl isophthalate resin, high pigment dispersibility can be obtained even when using a neutral carbon black pigment with poor dispersibility. As a result, the dispersibility and fluidity of the ink are significantly improved. Examples of commercially available diallyl isophthalate resins include Daiso Isodap manufactured by Osaka Soda Co., Ltd.

[0027] In the present invention, the content of the diallyl isophthalate resin is 13 to 30% by mass in the total amount of the resin, preferably 15 to 25% by mass, and more preferably 17 to 20% by mass.

[0028] In the present invention, the diallyl isophthalate resin preferably has a weight-average molecular weight of 2,000 to 30,000, and more preferably 3,000 to 15,000. A weight-average molecular weight of 2,000 to 30,000 results in good abrasion resistance and adhesion, and also improves dispersibility by increasing wettability to colorants.

[0029] <Resins other than diallyl isophthalate resin> The ink of the present invention contains at least one resin other than diallyl isophthalate resin (hereinafter referred to as "other resin"). The other resin can be appropriately selected according to the desired physical properties, but a resin that has good compatibility with and is soluble in (meth)acrylate compounds is preferred.

[0030] Other resins include, specifically, diallyl orthophthalate resin, rosin-modified resin, polyester resin, epoxy resin, and urethane resin.

[0031] The other resins preferably include at least one selected from the group consisting of diallyl orthophthalate resins and rosin-modified resins, and more preferably include diallyl orthophthalate resins and rosin-modified resins.

[0032] The inclusion of diallyl orthophthalate resin allows for maintaining a balance of fluidity without inhibiting ink curing properties. Furthermore, the inclusion of rosin-modified resin improves the ink emulsification rate.

[0033] In this invention, a commercially available example of the diallyl orthophthalate resin is Daiso Dapp manufactured by Osaka Soda Co., Ltd.

[0034] In the present invention, the diallyl orthophthalate resin preferably has a weight-average molecular weight of 2,000 to 30,000, and more preferably 3,000 to 15,000. A weight-average molecular weight of 2,000 to 30,000 results in good abrasion resistance and adhesion.

[0035] In this invention, the rosin-modified resin refers to a resin containing a rosin-derived skeleton within its resin backbone. By containing a rosin-derived skeleton, curing shrinkage due to UV irradiation during high-speed printing can be suppressed, and the smoothness of the dried film can be maintained, thereby improving gloss and adhesion.

[0036] Furthermore, the rosin-modified resin in the present invention is preferably a reaction product of an addition reaction between rosin acids (A) and an α,β-unsaturated carboxylic acid or its acid anhydride (B), and a polyol (C). More specifically, rosin-modified resins are preferred that are obtained by a Diels-Alder reaction between an organic acid having a conjugated double bond contained in rosin acids (A) and an α,β-unsaturated carboxylic acid or its acid anhydride (B), an organic acid from rosin acids (A) that does not have a conjugated double bond, and other organic acids, in which a hydroxyl group of a compound formed by the reaction of a carboxylic acid with a polyol (C) to form an ester bond is reacted with the hydroxyl group to form an ester bond.

[0037] <Rosin Acids (A)> The rosin acids (A) used to obtain the rosin-modified resin in the present invention refer to monobasic acids having a cyclic diterpene skeleton. These include rosin acid, disproportionated rosin acid, hydrogenated rosin acid, or alkali metal salts of the above compounds. Specifically, examples include abietic acid having a conjugated double bond, and its conjugated compounds, such as neoabietic acid, palastic acid, and levopimaric acid, as well as pimaric acid, isopimaric acid, sandaracopimalic acid, and dehydroabietic acid, which do not have a conjugated double bond. Examples of natural resins containing these rosin acids (A) include gum rosin, wood rosin, and tall oil rosin.

[0038] The amount of rosin acid (A) used to obtain the rosin-modified resin in the present invention is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass, based on the total amount of resin raw materials. If the amount of rosin acid (A) is 20% by mass or more, the gloss of the active energy ray curable coating varnish containing the resin will be good, and if the amount is 70% by mass or less, the abrasion resistance of the active energy ray curable coating varnish will be good.

[0039] <α,β-unsaturated carboxylic acids or their acid anhydrides (B)> Examples of α,β-unsaturated carboxylic acids or their acid anhydrides (B) used to obtain the rosin-modified resin in the present invention include maleic acid, fumaric acid, citraconic acid, itaconic acid, crotonic acid, isocrotonic acid, and their acid anhydrides. Considering the reactivity with rosin acids (A), maleic acid or its acid anhydride is preferred.

[0040] In the present invention, the amount of α,β-unsaturated carboxylic acid or its acid anhydride (B) is preferably in the range of 60 to 200, more preferably in the range of 70 to 180 mol%, and particularly preferably in the range of 80 to 155 mol% relative to rosin acids (A). When the amount of α,β-unsaturated carboxylic acid or its acid anhydride (B) is adjusted within the above range, it is easy to obtain a rosin-modified resin with excellent friction resistance and adhesion.

[0041] <Carboxylic acids other than (A) and (B) (hereinafter also referred to as "other organic acids")> In order to obtain the rosin-modified resin in the present invention, in addition to rosin acids (A) and α,β-unsaturated carboxylic acids or their acid anhydrides (B), other organic acids may be used individually or in pairs or more. The amount of other organic acids is preferably 0 to 30% by mass, and more preferably 0 to 20% by mass, based on the total amount of resin raw materials.

[0042] Other specific examples of organic acids include, but are not limited to, the following.

[0043] <Organic monobasic acid> Aromatic monobasic acids such as benzoic acid, methylbenzoic acid, tert-butylbenzoic acid, naphthoic acid, and orthobenzoylbenzoic acid. Compounds that have a conjugated double bond but do not have a cyclic diterpene skeleton, such as conjugated linoleic acid, eleostearic acid, parinalic acid, and calencic acid. These are some examples.

[0044] <Alicyclic polybasic acids or their acid anhydrides> Examples include 1,2,3,6-tetrahydrophthalic acid, 3-methyl-1,2,3,6-tetrahydrophthalic acid, 4-methyl-1,2,3,6-tetrahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and their acid anhydrides.

[0045] (Other organic polybasic acids or their acid anhydrides) Examples include oxalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, sebacic acid, azelaic acid, alkenyl succinic acids such as dodecenyl succinic acid and pentadecenyl succinic acid, o-phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, and their acid anhydrides.

[0046] <Polyol (C)> Polyol (C) is a compound obtained by the Diels-Alder reaction between an organic acid having a conjugated double bond, which is included in rosin acids (A), and an α,β-unsaturated carboxylic acid or its acid anhydride (B). It also forms ester bonds through reactions with carboxylic acids in organic acids from rosin acids (A) that do not have a conjugated double bond, and other organic acids. To obtain the rosin-modified resin in the present invention, the polyols described below can be used individually or in combination of two or more types. Specific examples of polyols are listed below, but are not limited to these.

[0047] (Linear alkylene divalent polyol) 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,2-octanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol, 1,12-dodecanediol, 1,2-dodecanediol, 1,14-tetradecanediol, 1,2-tetradecanediol, 1,16-hexadecanediol, 1,2-hexadecanediol, etc.

[0048] <Branched alkylene divalent polyol> 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, dimethyloloctane, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, etc.

[0049] <Cyclic divalent polyol> Cyclic alkylene divalent polyols such as 1,2-cycloheptanediol, tricyclodecanedimethanol, 1,2-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated bisphenol S, hydrogenated catechol, hydrogenated resorcinol, and hydrogenated hydroquinone; aromatic divalent polyols such as bisphenol A, bisphenol F, bisphenol S, catechol, resorcinol, and hydroquinone.

[0050] <Other divalent polyols> Divalent polyether polyols such as polyethylene glycol (n=2~20), polypropylene glycol (n=2~20), and polytetramethylene glycol (n=2~20), as well as polyester polyols, etc.

[0051] <Trivalent polyol> Glycerin, trimethylolpropane, 1,2,6-hexanetriol, 3-methylpentane-1,3,5-triol, hydroxymethylhexanediol, trimethyloloctane, etc.

[0052] <Polyols with tetravalent or higher valent properties> Linear, branched, and cyclic polyols with tetravalent or higher nucleotides, such as pentaerythritol, diglycerin, ditrimethylolpropane, dipentaerythritol, sorbitol, inositol, and tripentaerythritol.

[0053] The rosin-modified resin in this invention preferably has a weight-average molecular weight of 3,000 to 30,000, and more preferably 3,000 to 15,000. A weight-average molecular weight of 3,000 to 30,000 results in good gloss and adhesion.

[0054] In the present invention, the rosin-modified resin preferably has an acid value of 20 to 80 mgKOH / g, more preferably 30 to 80 mgKOH / g, even more preferably 40 to 80 mgKOH / g, and particularly preferably 50 to 80 mgKOH / g. When the acid value of the rosin-modified resin is within the above range, it exhibits excellent adhesion.

[0055] Furthermore, the melting point of the rosin-modified resin is preferably 50°C or higher, and more preferably in the range of 60 to 100°C. The melting point can be measured using a MeltingPoint M-565 manufactured by BUCHI under a heating rate of 0.5°C / min.

[0056] <(meth)acrylate compounds> The ink of the present invention contains a (meth)acrylate compound. The (meth)acrylate compound in the present invention is not particularly limited as long as it is a compound having a (meth)acryloyl group. Furthermore, in the present invention, the (meth)acrylate compound may be one type or a combination of two or more types, but from the viewpoint of ink viscosity and curability, it is preferable to combine two or more types, and more preferable to combine three or more types.

[0057] The ink of the present invention contains a (meth)acrylate compound as the (meth)acrylate compound, which has three or more (meth)acryloyl groups in its molecule. By including a (meth)acrylate compound with three or more (meth)acryloyl groups in its molecule, both curability and fluidity can be achieved. In particular, from the viewpoint of curability, it is preferable to include a (meth)acrylate compound that has three to six (meth)acryloyl groups in its molecule.

[0058] The total content of (meth)acrylate compounds containing three or more (meth)acryloyl groups in the molecule is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the total mass of the (meth)acrylate compounds.

[0059] In the present invention, the content of the (meth)acrylate compound is preferably 30 to 60% by mass, and more preferably 35 to 50% by mass, of the total amount of ink.

[0060] Specifically, (meth)acrylate compounds containing three or more (meth)acryloyl groups in the molecule include trimethylolpropane tri(meth)acrylate, EO-modified (3) trimethylolpropane tri(meth)acrylate, EO-modified (6) trimethylolpropane tri(meth)acrylate, PO-modified (3) trimethylolpropane tri(meth)acrylate, ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate, ethoxylated isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and other (meth)acrylate compounds having three (meth)acryloyl groups in the molecule. (Meth)acrylate compounds having four acryloyl groups in their molecule, such as pentaerythritol tetra(meth)acrylate, EO-modified (4) pentaerythritol tetra(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. (Meth)acrylate compounds having five (meth)acryloyl groups in their molecule, such as dipentaerythritol penta(meth)acrylate. Examples include (meth)acrylate compounds having six (meth)acryloyl groups in the molecule, such as dipentaerythritol hexa(meth)acrylate.

[0061] Furthermore, a (meth)acrylate compound having one or two (meth)acryloyl groups can also be used in combination.

[0062] Furthermore, other urethane (meth)acrylates such as aliphatic urethane (meth)acrylate and aromatic urethane (meth)acrylate, as well as polyester (meth)acrylate and epoxy (meth)acrylate, can also be used as (meth)acrylate compounds.

[0063] <Body pigments> The ink of the present invention contains an extender pigment. By including an extender pigment, the balance between ink tack and viscosity is maintained, and misting resistance is improved. Examples of extender pigments include clay, talc, barium sulfate, calcium carbonate, heavy calcium carbonate, barium carbonate, magnesium carbonate, and bentonite.

[0064] The extender pigment content in the ink of the present invention is preferably 0.5 to 3.0% by mass of the total ink amount, and more preferably 1.0 to 2.5% by mass.

[0065] The extender pigment in this invention preferably contains at least one selected from the group consisting of magnesium carbonate and talc. Including these helps maintain a balance between ink tack and viscosity, and improves misting resistance.

[0066] <Other ingredients> The ink of the present invention may contain, if necessary, a photopolymerization initiator, silica, a sensitizer, a polymerization inhibitor, and the like, in addition to the above-mentioned components.

[0067] <Photopolymerization initiator> The ink of the present invention may contain a photopolymerization initiator. There are no particular limitations on the photopolymerization initiator that can be used in the present invention, and known photopolymerization initiators can be used. Specific examples include benzophenone compounds, dialkoxyacetophenone compounds, α-hydroxyalkylphenone compounds, α-aminoalkylphenone compounds, acylphosphine oxide compounds, and thioxanthone compounds. Furthermore, the photopolymerization initiator may be used alone or in combination of two or more types.

[0068] Examples of the benzophenone compounds mentioned above include benzophenone, 4-methylbenzophenone, 4-phenylbenzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, and [4-(methylphenylthio)phenyl]phenylmethanone.

[0069] Examples of the above-mentioned dialkoxyacetophenone compounds include 2,2-dimethoxy-2-phenylacetophenone, dimethoxyacetophenone, and diethoxyacetophenone.

[0070] Examples of the above-mentioned α-hydroxyalkylphenone compounds include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxymethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methylpropan-1-one.

[0071] Examples of the α-aminoalkylphenone compounds mentioned above include 2-methyl-1-[4-(methoxythio)-phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone.

[0072] Examples of the acylphosphine oxide compounds mentioned above include diphenylacylphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0073] Examples of the thioxanthone compounds mentioned above include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, and 2,4-diethylthioxanthone.

[0074] The content of the photopolymerization initiator is preferably 1 to 20% by mass of the total amount of ink, and more preferably 5 to 15% by mass.

[0075] <Silica> The ink of the present invention may contain silica. Preferably, the silica content in the ink of the present invention is 0.5 to 1.5% by mass of the total ink volume. The inclusion of silica can reduce the fouling of halftone dots.

[0076] <Sensitizer> The ink of the present invention may contain a sensitizer. Including a sensitizer can further improve curability. Specific examples of sensitizers include triethanolamine, methyldiethanolamine, triisopropanolamine, aliphatic amines, ethyl 2-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, and dibutylethanolamine.

[0077] <Polymerization inhibitors> The ink of the present invention may contain a polymerization inhibitor. Specific examples of polymerization inhibitors include 4-methoxyphenol, hydroquinone, methylhydroquinone, t-butylhydroquinone, 2,6-di-t-butyl-4-methylphenol, phenothiazine, and aluminum salts of N-nitrosophenylhydroxylamine.

[0078] From the viewpoint of maintaining curability while improving ink stability, the content of the polymerization inhibitor is preferably 0.01 to 2% by mass of the total ink volume.

[0079] The black ink of the present invention preferably contains substantially no water. "Substantially no water" means that the water content is 2% by mass or less of the total ink volume.

[0080] The black ink of the present invention preferably contains substantially no organic solvents. "Substantially no" means that the amount of organic solvents is 1% by mass or less of the total ink volume.

[0081] <Printed material> The printed material of the present invention is obtained by printing the ink of the present invention onto a substrate and curing it with active energy rays.

[0082] The substrate used in this invention is not particularly limited as long as it is a paper substrate, and known types can be used. Specifically, examples include coated papers such as art paper, coated paper, and cast paper; newsprint such as fine paper, medium-quality paper, and newspaper; and synthetic papers such as Yupo paper.

[0083] Methods for printing the ink of the present invention onto a substrate include offset printing (conventional lithographic printing using dampening solution and waterless lithographic printing without dampening solution), flexographic printing, gravure printing, screen printing, and inkjet printing, among which it is preferable to use it for lithographic printing.

[0084] In the present invention, there are no particular limitations on the method for curing the ink, and known methods can be used. For example, curing can be performed by irradiating with alpha rays, gamma rays, electron beams, X-rays, ultraviolet rays, visible light, or infrared light. Among these, ultraviolet rays and electron beams are preferred, and ultraviolet rays are more preferred. The peak wavelength of the ultraviolet rays is preferably 200 to 600 nm, and more preferably 350 to 420 nm.

[0085] There are no particular restrictions on the active energy source, and known sources can be used. Specifically, examples include mercury lamps, xenon lamps, metal hydride lamps, ultraviolet light-emitting diodes (UV-LEDs), ultraviolet laser diodes (UV-LDs), and other LEDs (light-emitting diodes), as well as gas and solid-state lasers. Among these, ultraviolet light-emitting diodes (UV-LEDs) are preferred. [Examples]

[0086] The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited in any way by the following examples. In the examples and comparative examples, "parts" and "%" represent "parts by mass" and "mass%", respectively.

[0087] <Preparation of resin varnish A> Thirty parts of diallyl isophthalate resin (manufactured by Osaka Soda Co., Ltd., Daiso Isodap) were dissolved in 70 parts of ditrimethylolpropanetetraacrylate, and the mixture was heated and mixed at a temperature of 80°C to create resin varnish A. <Preparation of resin varnish B> 28 parts of diallyl orthophthalate resin (Daiso Dap A, manufactured by Osaka Soda Co., Ltd.) were dissolved in 60 parts of dipentaerythritol hexaacrylate and 12 parts of ditrimethylolpropane tetraacrylate, and the mixture was heated and mixed at a temperature of 80°C to prepare resin varnish B. <Preparation of resin varnish C> Forty parts of rosin-modified resin 1 (resin 4 described in paragraph 0076 of International Publication No. 2017 / 164246) were dissolved in 60 parts of ditrimethylolpropanetetraacrylate, and the mixture was heated and mixed at a temperature of 80°C to prepare resin varnish C. <Preparation of resin varnish D> Forty parts of rosin-modified resin 2 (resin 5 described in paragraph 0076 of International Publication No. 2017 / 164246) were dissolved in 60 parts of ditrimethylolpropanetetraacrylate, and the mixture was heated and mixed at a temperature of 80°C to prepare resin varnish D.

[0088] <Creation of activated energy ray-curing black ink> Example 1 A mixture of 15 parts of #85L carbon black with a pH of 7.0-8.5, 10 parts of EO(3)-modified trimethylolpropane triacrylate (TMP(EO)TA), 10 parts of ditrimethylolpropane tetraacrylate (DiTMPTA), 10 parts of dipentaerythritol hexaacrylate (DPHA), 2.5 parts of OmniradDETX, 3 parts of OmniradEMK, 5 parts of Omnirad930, 1 part of silica, 2.5 parts of magnesium carbonate, 0.5 parts of talc, 0.5 parts of polymerization inhibitor, and 10 parts of resin varnish A, 15 parts of resin varnish B, and 15 parts of resin varnish C was mixed and stirred using a butterfly mixer, and then dispersed using a three-roll mixer to a maximum particle size of 7.5 μm or less to prepare the ink.

[0089] Examples 2-14, Comparative Examples 1-11 Except for changing the raw materials and quantities listed in Table 1, the inks of Examples 2-14 and Comparative Examples 1-11 were obtained using the same method as in Example 1. A blank space indicates that the ingredient was not included.

[0090] [Table 1]

[0091] [Table 1]

[0092] The following is an explanation of the notation in Table 1. [Pigments] • #85L: Carbon black (pH 7.5) manufactured by Mitsubishi Chemical Corporation. • #25: Carbon black (pH 8.0) manufactured by Mitsubishi Chemical Corporation. • #2600: Carbon black (pH 6.5) manufactured by Mitsubishi Chemical Corporation. • MA-14: Carbon black (pH 2.4) manufactured by Mitsubishi Chemical Corporation. • MA-11: Manufactured by Mitsubishi Chemical Corporation, carbon black (pH value 2.4) [(meth)acrylate compounds] • TMP(EO)TA: MIRAMER M3130 (manufactured by MIWON) • DiTMPTA:EBECRYL 1142 (manufactured by Daicel Ornex Co., Ltd.) • DPHA: MIRAMER M600 (manufactured by MIWON) [Photopolymerization initiator] • OmniradDETX: Manufactured by IGM Resins, thioxanthone • OmniradEMK: Manufactured by IGM RESINS, benzophenone • Omnirad930: α-aminoacetophenone, manufactured by IGM RESINS. (Extender pigments) • Magnesium carbonate: Magnesium carbonate manufactured by Naikai Salt Industry Co., Ltd. • Calcium carbonate: Neolite EG-290 (manufactured by Takehara Chemical Industry Co., Ltd.) • Talc: Manufactured by Matsumura Sangyo Co., Ltd., High Filler 5000PJ [others] (silica) • Silica: NipSeal LP (manufactured by Tosoh Silica Co., Ltd.), hydrophilic wet silica (Polymerization inhibitor) • Q-1301: N-nitrosophenylhydroxylamine aluminum (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0093] The obtained inks were evaluated for their performance using the following method. The results are shown in Table 2. [Dispersibility] The obtained ink and ditrimethylolpropanetetraacrylate were mixed in a 2:1 mass ratio, and the dispersibility was measured using a particle size analyzer (grindometer) according to JIS K5600-2-5. Levels 4 and 3 were evaluated as being at a level that poses no practical problems. 4. Particle size is 5.0 microns or less. 3: Particle size is 7.5 microns or less 2: Particle size is 10.0 microns or less 1: Particle size 12.5 microns or less

[0094] [Liquidity] The obtained ink was dropped at a rate of 3g onto a brass inclined plate tilted at 60° in a 25°C atmosphere, and the distance the ink flowed from the point of contact over 10 minutes (static flow) was measured to evaluate its fluidity. Levels of 5, 4, and 3 are considered to be at a level that is acceptable for practical use, while levels of 5 and 4 are considered to be at a level that is preferable for practical use. 5. The static flow rate is 120 mm or more. 4. The static flow is 90 mm or more and less than 120 mm. 3: The static flow is 60 mm or more and less than 90 mm. 2: The static flow is 30 mm or more and less than 60 mm. 1: The static flow rate is less than 30 mm.

[0095] [Curability] The obtained ink composition was used to prepare a colored sample (substrate: non-absorbent base material) using an RI tester (manufactured by Tester Industries Co., Ltd.) with a 4-part roll and an ink volume of 0.75 ml. Subsequently, it was cured using an I-Graphics UV curing device (160 W / cm²). 2 The printed surface was completely dried by irradiating it with ultraviolet light using a metal halide lamp at a conveyor speed of 60 m / min. The printed surface was then evaluated by rubbing it with a cotton cloth. Less rubbing indicates better curing performance. Levels 4 and 3 were evaluated as being at a level that poses no practical problems. 4: No rubbing on the printed surface. 3: Scratches up to the surface layer of the printed surface 2: Scratches up to the middle of the printed surface 1: Scratches down to the bottom of the printed surface

[0096] [Smudges on halftone dots] The printing test involved continuously printing 5,000 copies of a typical image with a typical density using a LITHRONE26 printer manufactured by Komori Corporation under the following conditions. During printing, the paper surface was checked for stains as needed, and the water dial was raised to adjust the dampening water supply each time a stain was detected. The amount the water dial rose after the operation was completed was evaluated. Levels 5, 4, and 3 were evaluated as acceptable for practical use, while levels 5 and 4 were evaluated as desirable for practical use. "Water level limit" refers to the minimum amount of dampening solution that can be supplied for normal printing, and "water dial" refers to the dial provided on the printing press used to adjust the amount of dampening solution supplied. 5. The water level rise after the end of operation is less than 3. 4. The water level rise after the end of operation is less than 5. 3. The water level rise after the end of operation is less than 7. 2: The water level rise after the end of operation is less than 9. 1: The water level rises by 10 or more after the operation is complete. (Printing conditions) Printing press: LITHRONE26 (manufactured by Komori Corporation) CTP version: Fujifilm Corporation XP-F Paper: OK Topcoat+ manufactured by Oji Paper Co., Ltd. Dampening solution: Tap water / PRESSMAX W-P1 (manufactured by FFGS) mixed in a 98 / 2 mass ratio. Printing speed: 10000 sheets / hour Lamp: LED lamp (manufactured by iGraphics, 100% output, 2 lamps used) Chiller setting temperature: 25℃ Water dial value: Start at a value 2 higher than the lower limit of the water range.

[0097] [Misting resistance] During the printing test described above, a blank sheet of paper was attached to the inside of the printing press's safety cover. After running 5,000 copies, the blank sheet was removed, and the degree of ink splatter was evaluated on a three-point scale according to the following criteria. Levels 3 and 2 are practically preferable. 3: A small amount of ink mist is scattered on a part of the blank paper. 2: Ink mist is scattered across the entire blank page. 1: The entire blank page is covered in thick ink mist. [Table 2]

[0098] From the above, it has been found that the active energy ray curable black ink of the present invention provides an active energy ray curable black ink that has ink dispersibility and fluidity equivalent to that of acidic carbon black even when using neutral carbon black, and that can reduce the staining of halftone dots, and that printed materials using this ink can be provided.

Claims

1. An active energy ray curable black ink containing a coloring agent, two or more types of resin, a (meth)acrylate compound, and an extender pigment, The coloring agent contains carbon black pigment with a pH value of 7.0 to 8.

5. The resin contains diallyl isophthalate resin in an amount of 13 to 30% by mass of the total resin, and also contains rosin-modified resin. An active energy ray curable black ink containing a (meth)acrylate compound that has three or more (meth)acryloyl groups in its molecule.

2. The active energy ray curable black ink according to claim 1, wherein the resin comprises a diallyl orthophthalate resin.

3. The active energy ray curable black ink according to claim 1, wherein the rosin-modified resin is a reaction product of an addition reaction product of rosin acids (A) and an α,β-unsaturated carboxylic acid or its acid anhydride (B) and a polyol (C).

4. The activated energy ray-curable black ink according to claim 1, wherein the total content of the aforementioned resin is 8 to 20% by mass of the total amount of ink.

5. The active energy ray-curable black ink according to claim 1, wherein the extender pigment comprises at least one selected from the group consisting of magnesium carbonate, calcium carbonate, and talc.

6. Furthermore, the active energy ray curable ink according to claim 1, further comprising silica.

7. A printed material obtained by printing an active energy ray-curable black ink according to any one of claims 1 to 6 onto a substrate and curing it with active energy rays.

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