JP2020164656A - Active energy ray-curable printing ink, and method of producing printed matter using the same - Google Patents

Abstract

To provide an active energy ray-curable printing ink having excellent storage stability even when a metallic pigment is used for the active energy ray-curable printing ink, and a method of producing printed matter using the same.SOLUTION: An active energy ray-curable printing ink comprises (a) a metallic pigment, (b) an acrylic resin having an acidic group, (c) a polyfunctional (meth)acrylate, and (d) a photoinitiator, and contains a compound represented by the formula in the figure, where R1 to R10 each independently represent a methyl group or hydrogen.SELECTED DRAWING: None

Description

The present invention relates to an active energy ray-curable printing ink and a method for producing a printed matter using the ink.

In recent years, the use of active energy ray-curable printing ink, which can be instantly cured by irradiating it with active energy rays such as ultraviolet rays, has been widely used due to its high equipment, safety, environment, and productivity. It is spreading in the field. Further, since the active energy ray-curable printing ink can be cured in a short time at room temperature, it is considered to be the most suitable material for forming a film on a plastic substrate having poor heat resistance. However, the active energy ray-curable ink composition usually contains a polymerizable compound in the ink composition, and the polymerization reaction proceeds even during storage due to radicals generated in the composition. In some cases, it may cause an increase in viscosity and gelation.

In order to solve this problem, for example, Patent Document 1 describes an active energy ray-curable ink composition containing a quinone derivative such as methquinone and an aluminum salt of N-nitrosophenylhydroxylamine as a storage stabilizer. There is.

Japanese Unexamined Patent Publication No. 2003-261817 (paragraph 0021)

However, even if the polymerization inhibitor described in Patent Document 1 is added to prepare an active energy ray-curable printing ink, it is still being stored, especially when aluminum powder is used as the pigment among the metal pigments. There was a problem that the polymerization reaction proceeded and the viscosity increased and gelation occurred.

Therefore, an object of the present invention is an active energy ray-curable printing ink having excellent storage stability even when a metal pigment is used as the active energy ray-curable printing ink, and a method for producing a printed matter using the same. Is to provide.

That is, the present invention is an active energy ray-curable printing ink containing (a) a metal pigment, (b) an acrylic resin having an acidic group, (c) a polyfunctional (meth) acrylate, and (d) a photopolymerization initiator. The active energy ray-curable printing ink is characterized by containing a compound represented by the following general formula (1).

R ^{1 to} R ¹⁰ independently represent a methyl group or hydrogen.

According to the present invention, it is possible to obtain an active energy ray-curable printing ink having high storage stability and capable of suppressing an increase in viscosity and gelation during storage.

Hereinafter, the present invention will be specifically described.

The active energy ray-curable printing ink according to the present invention contains (a) a metal pigment. Examples of the metal pigment include an aluminum pigment, a zinc pigment, and a copper pigment. Among the (a) metal pigments, it is particularly preferable to use (a1) an aluminum pigment from the viewpoint of cost and metallic luster. The aluminum pigment (a1) used in the present invention may be ordinary aluminum powder, but an aluminum paste obtained by processing aluminum into fine scaly particles and making a paste with an organic solvent or the like is more preferably used. Compared with ordinary aluminum powder, aluminum paste is preferable because it has better dispersibility in active energy ray-curable printing ink and the hiding power is less likely to decrease when a printed matter is produced.

As the aluminum paste, there are a leafing type paste in which aluminum flakes float on the surface of the coating film due to surface tension and are arranged in parallel, and a non-leaving type paste in which the aluminum flakes are uniformly dispersed and arranged in the coating film, both of which are suitable. Can be used for. In particular, the non-leafing type aluminum paste can be preferably used because the occurrence of surface peeling of the printed matter can be suppressed as compared with the leafing type aluminum paste.

Further, when the surface of the (a1) aluminum pigment in the aluminum paste is coated with an acrylic resin or an acrylic monomer, the dispersibility is improved as compared with the above-mentioned aluminum paste, and the active energy ray-curable printing ink is used. Since the transferability becomes good, it can be used even more preferably.

The average particle size D50 of the (a1) aluminum pigment used in the present invention is preferably 3.0 μm or more in terms of improving dispersibility, and preferably 30 μm or less in order to maintain concealment and transferability. .. The average particle size D50 of the aluminum pigment referred to here refers to the particle size when the cumulative amount of passage from the small particle size side is 50% in the particle size distribution, and is the average particle size obtained by the following method. The value. From a two-dimensional image obtained by observing a particle with a scanning electron microscope (SEM), the one that maximizes the distance between the two intersections of the straight line that intersects the outer edge of the particle at two points is calculated, and the particle diameter is calculated. Is defined as. Further, the same measurement is performed on any 20 different particles, and the average particle diameter D50 is calculated using the obtained measured value of the particle diameter.

The active energy ray-curable printing ink according to the present invention contains (b) an acrylic resin having an acidic group.

Since it becomes soluble in a water-based cleaning solution containing water as a main component, which is a non-petroleum-based cleaning agent, (b) an acrylic resin having an acidic group preferably has an acidic group in the side chain.

Further, (b) in the acrylic resin having an acidic group, the viscosity of the active energy ray-curable printing ink increases due to the hydrogen bond between the acidic groups. When the ink has a high viscosity, the cohesive force of the ink under high shear during printing is increased, and the ink repulsion against non-image areas is improved. As a result, the ground stain resistance during lithographic printing is also improved. Contribute. Here, the background stain means that the ink adheres to the non-image area of the lithographic printing plate to which the ink originally does not adhere. As a result of the ink adhering to the non-image area of the lithographic printing plate, the ink is also transferred onto the printed matter.

(B) Specific examples of the acidic group of the acrylic resin having an acidic group include a carboxyl group, a sulfo group, and a phosphoric acid group, but from the viewpoint of solubility in water and good dispersibility of the pigment. , Carboxyl groups are particularly preferred.

Furthermore, (b) the acrylic resin having an acidic group preferably contains a resin having an ethylenically unsaturated group. (B) When the acrylic resin having an acidic group has an ethylenically unsaturated group, it is preferable because it has high sensitivity of active energy ray curability and also has excellent water resistance of the cured film. (B) When the acrylic resin having an acidic group has an ethylenically unsaturated group, the iodine value of the ethylenically unsaturated group is preferably 0.5 mol / kg or more and 3.0 mol / kg or less. When it is within the above range, the sensitivity of the active energy ray-curable lithographic printing ink to the active energy ray is high, and good storage stability can be obtained, which is preferable. The iodine value of the ethylenically unsaturated group of the resin is determined by JIS K0070: 1992, "Test method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products". It can be obtained by the method described in "Value".

(B) Acrylic resin having an acidic group can be produced by the following method. That is, a compound selected from carboxyl group-containing monomers such as acrylic acid, methacrylic acid, or these acid anhydrides, methacrylic acid ester, acrylic acid ester, styrene, acrylonitrile, vinyl acetate, and the like is used as a radical polymerization initiator. It is obtained by polymerization or copolymerization using. (B) When an ethylenically unsaturated group is further added to the acrylic resin having an acidic group, ethylene having a glycidyl group or an isocyanate group is compared with a carboxyl group which is an active hydrogen-containing group in the obtained polymer. It is obtained by an addition reaction of a sex unsaturated compound, acrylic acid chloride, methacrylate chloride or allyl chloride. However, the method is not limited to these methods.

Specific examples of the above-mentioned (b) acrylic resin having an acidic group include (meth) acrylic acid copolymer, (meth) acrylic acid- (meth) acrylic acid ester copolymer, and styrene- (meth) acrylic acid copolymer. Combined, styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene-maleic acid- (meth) acrylic acid copolymer, styrene-maleic acid- (meth) acrylic acid ester copolymer, etc. Can be mentioned.

The acid value of the acrylic resin having the (b) acidic group is preferably 30 mgKOH / g or more and 250 mgKOH / g or less. The acid value of the resin is preferably 30 mgKOH / g or more, more preferably 60 mgKOH / g or more, in order to obtain good solubility of the resin in an aqueous cleaning solution, dispersibility of pigments, and stain resistance. It is preferably 75 mgKOH / g or more, and more preferably 75 mgKOH / g or more. Further, in order to obtain water resistance of the cured film, it is preferably 250 mgKOH / g or less, more preferably 200 mgKOH / g or less, and even more preferably 150 mgKOH / g or less. The acid value of the resin in the first half is described in "Section 3.1 Neutralization Titration Method" of JISK0070: 1992 "Test Method for Acid Value, Saponification Value, Ester Value, Isoide Value, Hydroxyl Value and Unsaponified Product of Chemical Products". It can be obtained according to the method described.

Further, the weight average molecular weight of the acrylic resin having the acidic group (b) is preferably 5,000 or more, more preferably 15,000 or more, and more preferably 20,000 in order to obtain the water resistance of the cured film. The above is more preferable. Further, in order to obtain water solubility of the resin, it is preferably 100,000 or less, more preferably 75,000 or less, and further preferably 50,000 or less. (B) The weight average molecular weight of the acrylic resin having an acidic group can be obtained by measuring in terms of polystyrene using gel permeation chromatography (GPC).

The active energy ray-curable printing ink according to the present invention contains (c) a polyfunctional (meth) acrylate. By containing the (c) polyfunctional (meth) acrylate in addition to the (b) acrylic resin having an acidic group, the ink has high-sensitivity active energy ray curability and a cured film. Also has excellent water resistance. Generally, the number of functional groups of (c) polyfunctional (meth) acrylate is preferably about 2 to 6.

The molecular weight of the (c) polyfunctional (meth) acrylate is preferably 400 or more, and more preferably 600 or more, in order to reduce shrinkage stress during curing and improve adhesion. Further, the active energy ray curability is preferably 3,000 or less, and more preferably 2,000.

Further, the active energy ray-curable printing ink according to the present invention preferably contains (c) a polyfunctional (meth) acrylate having an alicyclic skeleton or an aliphatic skeleton having 6 to 18 carbon atoms. When the polyfunctional (meth) acrylate having the alicyclic skeleton or the aliphatic skeleton having 6 to 18 carbon atoms is contained in the active energy ray-curable lithographic printing ink, the viscosity and surface energy of the ink are lowered. Therefore, the transferability and leveling property of the ink are improved.

The viscosity of the polyfunctional (meth) acrylate having an alicyclic skeleton or an aliphatic skeleton having 6 to 18 carbon atoms at 25 ° C. and 1 atm is 50 mPa ·, which can maintain good ground stain resistance of the ink. It is preferably s or more, and more preferably 100 mPa · s or more. Further, in order to improve the fluidity of the ink and obtain good transferability and leveling property, it is preferably 300 mPa · s or less, and more preferably 200 mPa · s or less. The viscosity of the (c) polyfunctional (meth) acrylate is measured at 25 ° C. and 0.5 rpm using a B-type viscometer.

The alicyclic skeleton is preferably a tricyclodecane skeleton, which has a small volume shrinkage during curing and has good film physical properties such as scratch resistance of the cured film.

Specific examples of the (c) polyfunctional (meth) acrylate having an alicyclic skeleton or an aliphatic skeleton having 6 to 18 carbon atoms include, as a (meth) acrylate having an aliphatic skeleton having 6 to 18 carbon atoms in monofunctionality. Examples thereof include hexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and isostearyl (meth) acrylate, and examples of the (meth) acrylate having an alicyclic skeleton include an alicyclic skeleton. , Isobornyl (meth) acrylate, norbornyl (meth) acrylate, norbornan-2-methanol (meth) acrylate, cyclohexyl (meth) acrylate, tricyclopentenyl (meth) acrylate, tricyclopentenyloxy (meth) acrylate, tricyclodecanemono Examples thereof include methylol (meth) acrylate. In bifunctionality, as the (meth) acrylate having an aliphatic skeleton having 6 to 18 carbon atoms, it has 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, and an alicyclic skeleton ( Examples of the meta) acrylate include tricyclodecanedimethanol di (meth) acrylate. Among the above, tricyclodecanedimethanol di (meth) acrylate having an appropriate monomer viscosity and high sensitivity is particularly preferable.

The active energy ray-curable printing ink according to the present invention has (c) a polyfunctional skeleton or an aliphatic skeleton having 6 to 18 carbon atoms with respect to 100 parts by mass of the active energy ray-curable printing ink. When 5 parts by mass or more of (meth) acrylate is contained, the viscosity and surface tension of the ink are reduced, and the transferability to the plastic film is improved. Therefore, 10 parts by mass or more is more preferable. Further, in order to maintain good ground stain resistance of the ink, it has the alicyclic skeleton or an aliphatic skeleton having 6 to 18 carbon atoms with respect to 100 parts by mass of the active energy ray-curable printing ink (c). The polyfunctional (meth) acrylate is preferably 20 parts by mass or less, more preferably 15 parts by mass or less.

The ink according to the present invention contains (d) a photopolymerization initiator in order to improve the ink curability. Further, (d) a sensitizer may be contained to assist the effect of the photopolymerization initiator. There are mechanically different types of (d) photopolymerization initiators such as a single molecule direct cleavage type, an ion pair electron transfer type, a hydrogen abstraction type, and a two molecule complex system, and they should be selected and used. Can be done.

The (d) photopolymerization initiator used in the present invention is preferably one that generates an active radical species, and specific examples thereof include benzophenylone, methyl o-benzoylbenzoate, and 4,4-bis (dimethylamine) benzophenone. , 4,4-Bis (diethylamino) benzophenone, 4,4-dichlorobenzophenone, 4-benzoyl-4-methyldiphenylketone, dibenzylketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2- Phenyl-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, pt-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyl, benzyldimethyl Ketanol, benzylmethoxyethyl acetal, benzoin, benzoin methyl ether, benzoin butyl ether, anthraquinone, 2-t-butyl anthraquinone, 2-amyl anthraquinone, β-chloroanthraquinone, antron, benzanthron, dibenzosverone, methyleneanthron, 4- Azidobenzalacetophenone, 2,6-bis (p-azidobenzylidene) cyclohexanone, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-) Methoxycarbonyl) oxime, 1-phenyl-propanedione-2- (o-ethoxycarbonyl) oxime, 1,3-diphenyl-propanthrion-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propane Trion-2- (o-benzoyl) oxime, Michler ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, naphthalenesulfonyl chloride, quinolinesulfonyl chloride, N-phenylthioacridone, 4 , 4-azobisisobutyronitrile, diphenyldisulfide, benzthiazoledisulfide, triphenylphosphine, camphorquinone, carbon tetrabromide, tribromophenylsulfone, benzoin peroxide and eosin, photoreducing dyes such as methylene blue and ascorbin Examples thereof include a combination of reducing agents such as acid and triethanolamine.

Specific examples of the sensitizer include 2,4-diethylthioxanthone, isopropylthioxanthone, 2,3-bis (4-diethylaminobenzal) cyclopentanone, and 2,6-bis (4-dimethylaminobenzal) cyclohexanone. 2,6-bis (4-dimethylaminobenzal) -4-methylcyclohexanone, Michler ketone, 4,4-bis (diethylamino) -benzophenone, 4,4-bis (dimethylamino) chalcone, 4,4-bis (diethylamino) ) Calcon, p-dimethylaminocinnamylidene indanone, p-dimethylaminobenzylene indanone, 2- (p-dimethylaminophenylvinylene) -isonafthiazole, 1,3-bis (4-dimethylaminobenzal) acetone , 1,3-carbonyl-bis (4-diethylaminobenzal) acetone, 3,3-carbonyl-bis (7-diethylaminocoumarin), N-phenyl-N-ethylethanolamine, N-phenylethanolamine, N-trill Examples thereof include diethanolamine, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, 3-phenyl-5-benzoylthiotetrazole, 1-phenyl-5-ethoxycarbonylthiotetrazole and the like.

In the present invention, (d) one or more photopolymerization initiators and sensitizers can be used.

The content of the photopolymerization initiator (d) is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the active energy ray-curable printing ink. (D) By setting the content of the photopolymerization initiator within this range, good sensitivity and curability can be obtained. When a sensitizer is contained, the content thereof is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the active energy ray-curable printing ink. By keeping the content of the sensitizer within this range, the effect of (d) the photopolymerization initiator can be assisted.

The active energy ray-curable printing ink according to the present invention contains a compound represented by the following general formula (1).

R ^{1 to} R ¹⁰ independently represent a methyl group or hydrogen.

The active energy ray-curable printing ink containing (a) a metal pigment, (b) an acrylic resin having an acidic group, (c) a polyfunctional (meth) acrylate, and (d) a photopolymerization initiator is described in the above general formula (1). ) Is not included, the viscosity gradually increases during storage, and eventually gelation occurs. That is, by containing the compound represented by the general formula (1), the storage stability of the active energy ray-curable printing ink is improved, and the increase in viscosity and gelation during storage are suppressed.

The content of the compound represented by the general formula (1) is 0.01 part by mass with respect to 100 parts by mass of the ink because good storage stability of the active energy ray-curable printing ink can be obtained. The above is preferable, 0.3 parts by mass or more is more preferable, and 1 part by mass or less at which good sensitivity can be obtained is preferable. Further, the content of the compound represented by the general formula (1) is preferably 1 part by mass or more, and preferably 5 parts by mass or less with respect to 100 parts by mass of the aluminum pigment.

Examples of the compound represented by the general formula (1) include nitrosamine-based compounds, such as N-nitrosodiphenylamine, 3-methyl-N-nitrosodiphenylamine, 4-methyl-N-nitrosodiphenylamine, and bis (4). -Methylphenyl) Nitrosamine and the like can be mentioned, but N-nitrosodiphenylamine is preferably used because of its availability on the market.

On the other hand, even if a polymerization inhibitor other than the general formula (1) is contained in the active energy ray-curable printing ink according to the present invention, the effect of improving the storage stability of the ink cannot be obtained, and the viscosity during storage increases. And gelation cannot be suppressed. Examples of the polymerization inhibitor other than the general formula (1) include hydroquinone monomethyl ethers, hydroquinone-based polymerization inhibitors such as t-butylhydroquinone, cuperon, N-nitroso-N-phenylhydroxylamine aluminum salt, and N-nitroso-N-. Nitrosoamine-based polymerization inhibitors other than the compounds represented by the general formula (1) such as methylaniline, oxime-based polymerization inhibitors such as salicylaldehyde oxime, 5-dodecyl-salitylaldehyde oxime and alkylacetophenone oxime, N, N- Hydroxime-based polymerization inhibitors such as diethyl hydroxylamine, N, N-dibenzyl hydroxylamine, N-phenyl-N'-(1,3-dimethylbutyl) -p-phenylenediamine, N, N'-di-sec Examples thereof include phenylenediamine-based polymerization inhibitors such as -butyl-p-phenylenediamine, and phenothiazine-based polymerization inhibitors such as phenothiazine and 2-methoxyphenothiazine.

Among the nitrosamine-based polymerization inhibitors, the reason why only the compound represented by the general formula (1) contributes to the storage stability of the ink is not clear, but the following speculation is possible, for example. Is. That is, it is considered that a general nitrosamine-based polymerization inhibitor tends to easily interact with an acidic group in a resin because the functional group contains an amine. On the other hand, since the compound represented by the general formula (1) has phenyl groups on both sides of the nitroso group, it is considered that steric hindrance is likely to occur and the interaction with the acidic group in the resin is inhibited. .. Therefore, it is presumed that only the compound represented by the general formula (1) contributes to the storage stability of the ink.

Further, the active energy ray-curable printing ink according to the present invention preferably contains one or more components selected from a silicone liquid, an alkyl acrylate, a hydrocarbon solvent, and a fluorocarbon. It may also contain vegetable oils or fatty acid esters derived from vegetable oils. These components have the effect of reducing the ink adhesion to the silicone rubber, which is the non-image area of the waterless lithographic printing plate. Among the above components, alkyl acrylate is preferable because it cures when irradiated with active energy rays, and thus improves the water resistance of the cured film of the ink and at the same time improves the sensitivity to active energy rays.

Further, in the active energy ray-curable printing ink according to the present invention, additives such as wax, defoaming agent, transferability improver, and leveling agent can be used, if necessary.

The method for producing the active energy ray-curable printing ink according to the present invention will be described below.

The active energy ray-curable printing ink according to the present invention includes (a) a metal pigment, (b) an acrylic resin having an acidic group, (c) a polyfunctional (meth) acrylate, (d) a photopolymerization initiator, and the above-mentioned general. The compound represented by the formula (1) and any other component are obtained by heating and dissolving at 5 to 100 ° C., if necessary, and then uniformly mixing and dispersing with a stirrer / kneader. Examples of the stirring / kneading machine include a kneader, a three-roll mill, a ball mill, a planetary ball mill, a bead mill, a roll mill, an attritor, a sand mill, a gate mixer, a paint shaker, a homogenizer, and a self-revolving stirrer. Defoaming under vacuum or reduced pressure conditions is also preferably performed after mixing and dispersing, or in the process of mixing and dispersing.

The method for producing a printed matter using the ink according to the present invention is as follows.

First, the ink according to the present invention is printed on a substrate, and then the ink is cured by irradiating it with active energy rays to obtain a printed matter having an ink curing film.

As the base material, a film base material such as a polypropylene film, a polyester film, or a polyamide film is preferable, and a polypropylene film is most preferably used. It is preferable to use a film substrate that has been previously corona-treated in an air atmosphere or a nitrogen atmosphere. Further, the thickness of the film base material used in the present invention is more preferably 30 μm or less because it can be used for flexible packaging.

As a method of printing on the base material of the active energy ray-curable printing ink according to the present invention, it is applied on the base material by a well-known method such as flexographic printing, lithographic printing, gravure printing, screen printing, and bar coater. be able to. In particular, lithographic printing is preferably used because ink can be printed in large quantities at high speed and at low cost. There are two types of lithographic printing: a method using a lithographic printing plate without water and a method using a lithographic printing plate with water. The method for producing a printed matter according to the present invention preferably includes a step of printing on a film substrate using a lithographic printing plate.

The thickness of the ink curing film on the printed matter is preferably 0.1 to 50 μm. When the thickness of the ink curing film is within the above range, the ink cost can be reduced while maintaining good print quality.

Next, the ink coating film on the printed matter is cured by irradiating with active energy rays. As the active energy ray, any one having an excitation energy required for the curing reaction can be used, but for example, ultraviolet rays are preferably used. When curing by ultraviolet rays, an ultraviolet irradiation device such as a high-pressure mercury lamp, a xenon lamp, a metal halide lamp, or an LED is preferably used. Curing at a speed of 50 to 150 m / min is preferable from the viewpoint of productivity.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited thereto.

<Ink raw material>
(A1) Aluminum Pigment Aluminum Pigment 1: "BP-490PA" (manufactured by Toyo Aluminum K.K.) Acrylic resin coated product, non-leaving type, average particle size D50 is 7 μm
Aluminum pigment 2: "PCF7076A" (manufactured by Toyo Aluminum Co., Ltd.) Acrylic resin coating product, non-leaving type, average particle size D50 is 10 μm
Aluminum pigment 3: "BP-280PA" (manufactured by Toyo Aluminum K.K.) Acrylic resin coated product, non-leaving type, average particle size D50 is 10 μm
Aluminum pigment 4: "13UV" (manufactured by Asahi Kasei Metals Co., Ltd.) No resin coating, leafing type, average particle size D50 is 6 μm
Aluminum pigment 5: "18UV" (manufactured by Asahi Kasei Metals Co., Ltd.) No resin coating, leafing type, average particle size D50 is 8 μm.

(B) Acrylic resin having an acidic group 0.4 equivalents of glycidyl methacrylate is added to the carboxyl group of a copolymer of 25% by mass methyl methacrylate, 25% by mass styrene, and 50% by mass methacrylic acid. It was. The weight average molecular weight was 34,000, the acid value was 102, and the iodine value was 2.0.

(C) Polyfunctional (meth) acrylate Polyfunctional (meth) acrylate 1: Mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate "Miramer" (registered trademark) M340 (manufactured by MIWON), molecular weight 298, hydroxyl value 115 mgKOH / g ..
Polyfunctional (meth) acrylate 2: Tricyclodecanedimethanol diacrylate "NK ester" (registered trademark) A-DCP (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), molecular weight 304, has an alicyclic skeleton.

(D) Photopolymerization Initiator Photopolymerization Initiator 1: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide "Lucillin" (registered trademark) TPO (manufactured by BASF)
Photopolymerization Initiator 2: 2- [4- (Methylthio) Benzoyl] -2- (4-morpholinyl) Propane "Irgacure" (registered trademark) 907 (manufactured by BASF).

(Polymerization inhibitor)
Polymerization inhibitor 1: N-nitrosodiphenylamine (manufactured by Tokyo Kasei Co., Ltd.)
Polymerization inhibitor 2: Hydroquinone monomethyl ether (manufactured by Tokyo Kasei Co., Ltd.)
Polymerization inhibitor 3: Salicylaldehyde oxime (manufactured by Wako Pure Chemical Industries, Ltd.)
Polymerization inhibitor 4: N, N-diethylhydroxylamine (manufactured by Wako Pure Chemical Industries, Ltd.)
Polymerization inhibitor 5: N-nitroso-N-methylaniline (manufactured by Tokyo Kasei Co., Ltd.)
Polymerization inhibitor 6: Cuperon (manufactured by Wako Pure Chemical Industries, Ltd.)
Polymerization inhibitor 7: N-nitroso-N-phenylhydroxylamine aluminum salt (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
Polymerization inhibitor 8: t-butylhydroquinone (manufactured by Wako Pure Chemical Industries, Ltd.)
Polymerization inhibitor 9: 2-Methoxyphenothiazine (manufactured by Wako Pure Chemical Industries, Ltd.)
Polymerization inhibitor 10: Phenothiazine (manufactured by Wako Pure Chemical Industries, Ltd.)
Polymerization inhibitor 11: N, N'-di-sec-butyl-p-phenylenediamine (manufactured by Tokyo Kasei Co., Ltd.).

(Other)
Sensitizer: 4,4-bis (diethylamino) benzophenone (manufactured by Hodogaya Chemical Co., Ltd.)
Additive: Lauryl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
Film base material: Polypropylene film P2111 (manufactured by Toyobo Co., Ltd.) Film thickness 20 μm.

<Storage stability>
A container containing 100 g of the inks of Examples and Comparative Examples described later was placed in an incubator at 80 ° C. for one day. After one day, the container containing the ink was taken out, and the ink inside was mixed with a spatula to check for gelled ink. When there was gelled ink, the non-gelled portion of the ink was removed, and then the mass of the remaining ink was measured to calculate the gelled ratio. If 50% by mass or more of the ink is gelled, it is defective, if the ratio of gelled ink is 1 to 50% by mass, it is slightly defective, and if there is no gelled ink, it is good. I decided.

<Metastatic>
Using the inks of Examples and Comparative Examples described later, 0.1 g of ink is placed on a roller of an RI tester (PI-600, manufactured by Tester Sangyo Co., Ltd.), transferred to a film substrate, and then transferred to a film substrate. The weight of the ink was measured. The transfer rate of the ink from the roller was determined using the weight of the film substrate measured in advance. If the transfer rate of the ink is less than 10% by mass, the transferability is insufficient, and if the transfer rate is 10% by mass or more and less than 12% by mass, the transferability is good, and if the transfer rate is 12% by mass or more. For example, the metastatic property was judged to be extremely good.

<Tape peeling>
Using the inks of Examples and Comparative Examples described later, 0.1 g of ink was placed on a roller of an RI tester (PI-600, manufactured by Tester Sangyo Co., Ltd.) and transferred to a film substrate. Then, using an ultraviolet irradiation device (120 W / cm, one ultra-high pressure metal halide lamp) manufactured by USHIO Co., Ltd., the ink was cured at a belt conveyor speed of 50 m / min to prepare a printed matter. A cellophane tape (CT-24, manufactured by Nichiban Co., Ltd.) 3 cm was attached to the surface of the printed matter and immediately peeled off, and it was observed whether the printed matter was peeled off. When the printed matter was completely peeled off, the adhesion to the film substrate was poor, when a part of the printed matter was peeled off, it was slightly poor, and when the printed matter was not peeled off, it was judged to be good.

[Example 1]
The ink compositions shown in Table 1 were weighed and stirred at 2000 rpm for 15 minutes using a self-revolving stirrer (ARE-310, manufactured by Shinky Co., Ltd.) to obtain ink.

The obtained ink was evaluated for storage stability, transferability (transfer rate), and tape peeling (adhesion).

The storage stability of the produced ink was good because there was no gelled ink at all. The metastasis rate was 12.3% by mass, and the metastasis was extremely good. There was no tape peeling, and the adhesion to the film substrate was good.

[Examples 2 to 5]
A printing experiment was carried out in the same manner as in Example 1 except that the type of aluminum pigment was changed to 2 to 5, and storage stability, transferability (transfer rate), and tape peeling (adhesion) were evaluated.

The storage stability of the produced inks was good, with no gelled inks at all. The transfer rate was 12% by mass or more in Examples 2 to 3 using the pigment whose surface was coated with the acrylic resin, and the transferability was extremely good. The tape peeling was good in Examples 2 to 3 using the non-reefing type pigment without peeling, but in Examples 4 to 5 using the leafing type pigment, peeling was observed only on the surface, which was slightly poor. ..
Table 1 shows the composition and evaluation results of each component used in Examples 1 to 5.

[Examples 6 to 13]
A printing experiment was carried out in the same manner as in Example 1 except that the contents of the polymerization inhibitor 1 and the additive were changed to the amounts shown in Table 2, and storage stability, transferability (transfer rate), and tape peeling (transfer rate) were carried out. Adhesion) was evaluated.

Regarding the storage stability of the produced ink, the proportion of the gelled ink tended to increase when the content of the polymerization inhibitor was small, and the storage stability of Examples 6 to 8 was slightly poor. In Examples 9 to 13 in which the content of the polymerization inhibitor was 0.3 parts by mass or more, there was no gelled ink at all, and the storage stability was good. The metastasis rate was 12% by mass or more in all the examples, and the metastasis was extremely good. In the tape peeling, in Example 13 in which the content of the polymerization inhibitor is as large as 1.5 parts by mass, the sensitivity of the printed film is lowered and the curing is insufficient, so that the printed film is completely peeled off and the film substrate is peeled off. Adhesion with was poor. In Examples 6 to 12, the printing film was not peeled off by the tape peeling, and the adhesion to the film substrate was good. Table 2 shows the composition and evaluation results of each component used in Examples 6 to 13.

[Comparative Examples 1 to 10]
A printing experiment was carried out in the same manner as in Example 1 except that the type of the polymerization inhibitor was changed as shown in Table 3, and storage stability, transferability (transfer rate), and tape peeling (adhesion) were evaluated. ..

In all the comparative examples, the transferability and tape peeling of the produced ink were good, but in all the comparative examples, the ratio of gelled ink was 70% by mass or more, and the storage stability was poor. was. Table 3 shows the composition and evaluation results of each component used in Comparative Examples 1 to 10.

Claims (9)

An active energy ray-curable printing ink containing (a) a metal pigment, (b) an acrylic resin having an acidic group, (c) a polyfunctional (meth) acrylate, and (d) a photopolymerization initiator, which are generally described below. An active energy ray-curable printing ink containing a compound represented by the formula (1).

R ^{1 to} R ¹⁰ independently represent a methyl group or hydrogen. The active energy ray-curable printing ink according to claim 1, wherein the (a) metal pigment is (a1) an aluminum pigment. The active energy ray-curable printing ink according to claim 1 or 2, wherein the compound represented by the general formula (1) is N-nitrosodiphenylamine. The active energy ray-curable printing ink according to claim 2 or 3, wherein the aluminum powder contained in the aluminum pigment (a1) is coated on the surface with an acrylic resin or an acrylic monomer. The active energy ray-curable printing ink according to any one of claims 2 to 4, wherein the average particle size D50 of the aluminum pigment (a1) is 3.0 to 30 μm. The active energy ray-curable printing ink according to any one of claims 1 to 5, wherein the acrylic resin having an acidic group (b) contains an ethylenically unsaturated group. The active energy ray-curable printing ink according to any one of claims 1 to 6, wherein the acrylic resin having an acidic group (b) has an acid value of 30 mgKOH / g or more and 250 mgKOH / g or less. The invention according to any one of claims 1 to 7, wherein the content of the compound represented by the general formula (1) is 0.01 to 1 part by mass with respect to 100 parts by mass of the active energy ray-curable printing ink. Ink for active energy ray-curable printing. The step of printing the active energy ray-curable printing ink according to any one of claims 1 to 8 on a substrate using a lithographic printing plate, and the step of irradiating the active energy ray to cure the ink are included. , How to make printed matter.