Active energy ray curable ink tack reducing agent for lithographic printing, active energy ray curable ink for lithographic printing, and method for manufacturing printed materials using the same.

Abstract

To provide an active energy ray curable ink tack reducing agent for lithographic printing and an active energy ray curable ink for lithographic printing using the same, which can reduce ink tack by suppressing background staining during printing and the elution of unreacted components from the ink film after curing. [Solution] An active energy ray curable ink tack reducing agent for lithographic printing, comprising a compound having the characteristics of (1) and (2) below. (1) The molecule has two or more ethylenically unsaturated double bonds. (2) The kinematic viscosity at 25°C is 50 mm 2 It is miscible at 25°C with 30 parts by volume or more of dimethyl silicone oil at 100 parts by volume.

Description

[Technical Field]

[0001] The present invention relates to an active energy ray curable ink tack reducing agent for lithographic printing, an active energy ray curable ink for lithographic printing, and a method for manufacturing printed materials using the same. [Background technology]

[0002] Lithographic printing is a widely used printing method that provides high-speed, high-volume, and inexpensive printed materials. In recent years, the use of active energy ray curing inks for lithographic printing, which harden instantly when irradiated with active energy rays such as mercury lamps, metal halide lamps, light-emitting diodes, and electron beams, has spread to many fields due to its advantages in terms of equipment, safety, environmental friendliness, and productivity.

[0003] Traditionally, lithographic printing has often used paper as the printing medium, but in light of the need to diversify the printing mediums, printing on plastic films and other materials is also expanding. In particular, in recent years, there has been progress in exploring its application to flexible packaging printing used for daily necessities, food products, and pharmaceuticals, where thin plastic films are used as the printing medium.

[0004] Active energy ray curable inks for lithographic printing are considered ideal materials for forming ink films on plastic films with poor heat resistance because they can be cured at room temperature in a short time. Examples of such active energy ray curable inks for lithographic printing that have been proposed include active energy ray curable inks for lithographic printing having (a) a resin having hydrophilic groups, (b) a polyfunctional (meth)acrylate having hydrophilic groups, and (c) a bifunctional (meth)acrylate having a chain-like aliphatic skeleton with 8 to 18 carbon atoms (see, for example, Patent Document 1), and lithographic printing inks containing (a) a pigment, and (b) a resin having ethylenically unsaturated groups and hydrophilic groups, and (d) one or more compounds selected from silicone liquids, alkyl acrylates, hydrocarbon solvents, and fluorocarbons (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-98773 [Patent Document 2] Japanese Patent Publication No. 2018-188671 [Overview of the project] [Problems that the invention aims to solve]

[0006] The films used for printing on flexible packaging are generally thin films with a thickness of 50 μm or less, and because they are easily torn and stretched, there are limits to the tension that can be applied during printing. In lithographic printing, the ink transferred to the blanket is transferred to the film by cleavage within the ink layer, but especially when the printing area is large, if the film tension is low, the film is prone to shifting due to ink tack, so it is necessary to reduce the ink tack.

[0007] The active energy ray curable lithographic printing ink described in Patent Document 1 is suitable for use in flexible packaging printing using plastic film as the printing medium because of its excellent ink transfer properties. Furthermore, through our research, we have found that (c) a bifunctional (meth)acrylate having a chain-like aliphatic skeleton with 8 to 18 carbon atoms has the effect of lowering ink tack, but increasing the content of such bifunctional (meth)acrylate in the ink to further reduce ink tack presents a problem in that ink tends to adhere unintentionally to the non-image areas of the printing plate, a phenomenon known as background staining.

[0008] Patent Document 2 describes that (d) staining can be suppressed by including one or more compounds selected from silicone liquid, alkyl acrylate, hydrocarbon solvent, and fluorocarbon. Furthermore, according to the inventors' studies, these compounds have the effect of lowering ink tack. However, these compounds have a low reaction probability because they have few functional groups that react with active energy rays, and they are not easily incorporated into three-dimensional crosslinks during curing, so they have the problem of easily leaching out of the ink film after curing.

[0009] Therefore, the problem that the present invention aims to solve is to provide an active energy ray curable ink tack reducing agent for lithographic printing and an active energy ray curable ink for lithographic printing using the same, which can suppress background staining during printing and the elution of unreacted components from the ink film after curing, thereby reducing ink tack. [Means for solving the problem]

[0010] To solve the above problems, the present invention mainly has the following configuration. [1] An active energy ray curable ink tack reducing agent for lithographic printing, comprising a compound having the characteristics of (1) and (2) below. (1) The molecule has two or more ethylenically unsaturated double bonds. (2) The kinematic viscosity at 25°C is 50 mm 2 It is miscible at 25°C with 30 parts by volume or more of dimethyl silicone oil at 100 parts by volume. [2] The active energy ray curable ink tack reducing agent for lithographic printing according to [1], wherein the compound further has the following (3) characteristics. (3) The kinematic viscosity at 25°C is 5,000 mm² 2 It does not mix with 100 parts by volume of dimethyl silicone oil at 25°C in more than 200 parts by volume. [3] The active energy ray curable ink tack reducing agent for lithographic printing according to [1] or [2], wherein the ethylenically unsaturated double bond in (1) is derived from an alkenyl ether group. [4] The active energy ray curable ink tack reducing agent for lithographic printing according to [3], wherein the alkenyl ether group is a vinyl ether group. [5] The active energy ray curable ink tack reducing agent for lithographic printing according to any one of [1] to [4], wherein the active energy ray curable ink for lithographic printing is a waterless active energy ray curable ink for lithographic printing. [6] An active energy ray curable ink for lithographic printing, comprising (a) a resin, (b) a compound having two or more (meth)acryloyl groups in its molecule, and (c) an active energy ray curable ink tack reducing agent for lithographic printing described in any of [1] to [5]. [7] The active energy ray curable ink for lithographic printing according to [6], comprising 0.5 to 20% by mass of the active energy ray curable ink tack reducing agent for lithographic printing described in any of (c)[1] to [5] above. [8] A photocatalytic active energy ray curable ink for lithographic printing according to [6] or [7], substantially free of a photocationic polymerization initiator. [9] The active energy ray curable ink for lithographic printing according to any one of [6] to [8], wherein the active energy ray curable ink for lithographic printing is a waterless active energy ray curable ink for lithographic printing.

[10] A method for manufacturing a printed material, comprising the steps of transferring an active energy ray-curable ink for lithographic printing described in any of [6] to [9] onto a printing medium using a lithographic printing plate, and irradiating the transferred active energy ray-curable ink for lithographic printing with an active energy ray.

[11] The method for manufacturing a printed material according to

[10] , wherein the lithographic printing plate is a waterless lithographic printing plate having a silicone rubber layer as an ink-repellent layer.

[12] A method for manufacturing a printed material according to

[10] or

[11] , wherein the average thickness of the printing medium is 50 μm or less.

[13] A method for manufacturing a printed material according to any one of

[10] to

[12] , wherein the active energy beam is an electron beam.

[14] A method for manufacturing a printed material according to any one of

[10] to

[13] , wherein the printed material is for food packaging. [Effects of the Invention]

[0011] The active energy ray-curable ink tack reducer for lithographic printing and the active energy ray-curable ink for lithographic printing using the same can suppress background soiling during printing and the elution of unreacted components from the cured ink film, and can reduce the ink tack.

Mode for Carrying Out the Invention

[0012] Hereinafter, the present invention will be specifically described.

[0013] The active energy ray-curable ink tack reducer for lithographic printing according to the present invention (hereinafter may be abbreviated as "ink tack reducer") is composed of a compound having the following characteristics (1) and (2). The ink tack reducer of the present invention may contain two or more kinds of such compounds. (1) It has two or more ethylenically unsaturated double bonds in the molecule. (2) It is compatible with 100 parts by volume of dimethyl silicone oil having a kinematic viscosity of 50 mm 2 / s at 25°C in a volume of 30 parts or more at 25°C.

[0014] By having the characteristic of (1) above, the reaction probability of the ethylenically unsaturated double bond by the active energy ray is high, and it is easily incorporated into the three-dimensional crosslinking during curing, so that the elution from the cured ink film can be suppressed. By having the characteristic of (2) above, the ink tack can be reduced and the background soiling during printing can be suppressed. In (2), the kinematic viscosity at 25°C is 50 mm 2The compatibility of / s with dimethyl silicone oil is an indicator of how well it blends with silicone rubber, a component of the ink-repellent layer in typical lithographic printing plates. Compatibility of 30 parts by volume or more means that it blends appropriately with the silicone rubber that makes up the ink-repellent layer. As a result, the ink tack reducing agent covers the surface of the ink-repellent layer in a film-like manner, thereby reducing ink tack and suppressing background smudging during printing. By having the characteristics of (1) and (2) above, the ink tack reducing agent can reduce ink tack while suppressing the elution of such compounds from the ink film after curing, and further suppress background smudging during printing.

[0015] In (1) above, compounds having an ethylenically unsaturated double bond are preferably compounds having a (meth)acryloyl group, an alkenyl ether group, etc. Here, (meth)acryloyl group is a general term for acryloyl group and methacryloyl group, and examples of alkenyl ether groups include vinyl ether group, allyl ether group, propenyl ether group, etc. Compared to the ester bond contained in the (meth)acryloyl group, the ether bond contained in the alkenyl ether group has lower polarity and is more compatible with the components that make up the ink repulsion layer of the lithographic printing plate, thus further suppressing background staining. Furthermore, among alkenyl ethers, the vinyl ether group is more preferred, and because it is highly reactive, it can further suppress elution from the ink film after curing.

[0016] In (2) above, the kinematic viscosity at 25°C is 50 mm 2Examples of dimethyl silicone oils with a viscosity of 0.50 / s include KF-96-50cs (manufactured by Shin-Etsu Chemical Co., Ltd.), "DOWSIL®" SH200 Fluid 50cSt, "DOWSIL®" SH200 C Fluid 50cSt (both manufactured by Toray Dow Corning Co., Ltd.), "WACKER®" SILICONE FLUID AK 50 (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.), TSF451-50 (manufactured by Momentive Performance Materials Japan LLC), and DMS-T15 (manufactured by GELEST Inc.). When evaluating using any of these dimethyl silicone oils, comparable compatibility values ​​for ink tack reducing agents are obtained.

[0017] In (2) above, "compatible" means that the ink tack reducing agent and the kinematic viscosity at 25°C are 50 mm². 2 This means that the dimethyl silicone oil at / s has mutual affinity and mixes at the molecular level. Specifically, this can be determined as follows: In a temperature-controlled room at 25°C, the kinematic viscosity at 25°C is 50 mm². 2 100 volumes of dimethyl silicone oil ( / s) are placed in a sealable glass container, then 10 volumes of ink tack reducing agent are added, the container is sealed, and the mixture is shaken vigorously by hand for 5 minutes, after which it is allowed to stand. The mixture is considered "miscible" if no turbidity is observed visually, or if turbidity is observed but no clear phase separation (phase interface) is observed after standing for 7 days. On the other hand, "miscible" means that the phases separate without mixing. Specifically, the mixture is considered "miscible" if a clear phase separation (phase interface) is observed visually, or if turbidity is observed but a clear phase separation (phase interface) is observed after standing for 7 days. The kinematic viscosity at 25°C is 50 mm². 2When the dimethyl silicone oil of / s and the ink tack reducer are compatible, add, stir, and let stand in 10 - volume - part increments up to a maximum of 210 volume - parts, repeating the process until the ink tack reducer becomes incompatible, and evaluate the compatibility each time. If it is compatible at 10 volume - parts of the ink tack reducer and incompatible at 20 volume - parts of the ink tack reducer, it is determined as "compatible up to 10 volume - parts" or "incompatible beyond 10 volume - parts". If no phase separation is observed after adding 210 volume - parts of the ink tack reducer, stirring, and letting stand, it is determined as "compatible at 210 volume - parts or more".

[0018] In the above (2), it is preferably compatible at 80 volume - parts or more at 25°C, more preferably compatible at 130 volume - parts or more, and even more preferably compatible at 180 volume - parts or more.

[0019] The compound having the characteristics of (1) and (2) preferably further has the following characteristic of (3). (3) The kinematic viscosity at 25°C is 5,000 mm 2 It is not compatible beyond 200 volume - parts at 25°C with respect to 100 volume - parts of dimethyl silicone oil of / s.

[0020] The kinematic viscosity at 25°C is 5,000 mm 2 The compatibility with dimethyl silicone oil of / s is an index representing the ease of familiarity with ethylene - propylene - diene rubber (EPDM) used for the inking roller and blanket used during printing. By not being compatible beyond 200 volume - parts at 25°C, penetration and diffusion into EPDM can be suppressed, and an increase in ink tack due to contact with the inking roller or blanket and printing defects resulting from swelling and deformation of the inking roller or blanket can be suppressed. It is more preferably not compatible beyond 150 volume - parts, and even more preferably not compatible beyond 100 volume - parts.

[0021] In the above (3), the kinematic viscosity at 25°C is 5,000 mm 2Examples of dimethyl silicone oils with a viscosity of / s include KF-96-5,000cs (manufactured by Shin-Etsu Chemical Co., Ltd.), "DOWSIL®" SH200 Fluid 5,000cSt, "DOWSIL®" SH200 C Fluid 5,000cSt (both manufactured by Toray Dow Corning Co., Ltd.), "WACKER®" SILICONE FLUID AK 5,000 (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.), TSF451-5000 (manufactured by Momentive Performance Materials Japan LLC), and DMS-T35 (manufactured by GELEST Inc.). When evaluating using any of these dimethyl silicone oils, comparable compatibility values ​​for ink tack reducing agents are obtained.

[0022] In (3) above, "compatible" means, as in (2) above, that the ink tack reducing agent and the kinematic viscosity at 25°C is 5,000 mm². 2 This means that the dimethyl silicone oil at / s has mutual affinity and mixes at the molecular level, while "mismatched" means that the phases separate without mixing. Specifically, the kinematic viscosity at 25°C is 5,000 mmHg. 2 The evaluation can be performed in the same manner as in (2) above using dimethyl silicone oil of / s.

[0023] Compounds that satisfy all of the above characteristics (1) to (3) include, for example, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, 1,9-nonanediol divinyl ether, 1,10-decanediol divinyl ether, 1,12-dodecanediol divinyl ether, neopentyl glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, dicyclopentadiene dimethanol divinyl ether, tricyclodecanedimethanol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, tetrapropylene glycol divinyl ether, glycerin trivinyl ether, and propylene Glycerin oxide (PO) modified trivinyl ether, trimethylolpropane trivinyl ether, ethylene oxide (EO) modified trimethylolpropane trivinyl ether, PO modified trimethylolpropane trivinyl ether, pentaerythritol tetravinyl ether, PO modified pentaerythritol tetravinyl ether, ditrimethylolpropane tetravinyl ether, PO modified ditrimethylolpropane tetravinyl ether, 1,4-butanediol diallyl ether, 1,6-hexanediol diallyl ether, 1,9-nonanediol diallyl ether, 1,10-decanediol diallyl ether, 1,12-dodecanediol diallyl ether, neopentyl glycol diallyl ether, 1,Examples include 4-cyclohexanedimethanol diallyl ether, dicyclopentadiene dimethanol diallyl ether, tricyclodecane dimethanol diallyl ether, propylene glycol diallyl ether, dipropylene glycol diallyl ether, tripropylene glycol diallyl ether, tetrapropylene glycol diallyl ether, glycerin triallyl ether, PO-modified glycerin triallyl ether, trimethylolpropane triallyl ether, EO-modified trimethylolpropane triallyl ether, PO-modified trimethylolpropane triallyl ether, pentaerythritol tetraallyl ether, PO-modified pentaerythritol tetraallyl ether, ditrimethylolpropane tetraallyl ether, and PO-modified ditrimethylolpropane tetraallyl ether.

[0024] Compounds that satisfy all of the above characteristics (1) to (3) preferably have a boiling point of 200°C or higher, which can suppress volatilization during storage and use of the compound. Examples of such compounds include 1,6-hexanediol divinyl ether, 1,9-nonanediol divinyl ether, 1,10-decanediol divinyl ether, 1,12-dodecanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, dicyclopentadiene dimethanol divinyl ether, tricyclodecanedimethanol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, tetrapropylene glycol divinyl ether, glycerin trivinyl ether, PO-modified glycerin trivinyl ether, trimethylolpropane trivinyl ether, EO-modified trimethylolpropane trivinyl ether, PO-modified trimethylolpropane trivinyl ether, pentaerythritol tetravinyl ether, PO-modified pentaerythritol tetravinyl ether, ditrimethylolpropane tetravinyl ether, PO-modified ditrimethylolpropane tetravinyl ether Examples include ether, 1,6-hexanediol diallyl ether, 1,9-nonanediol diallyl ether, 1,10-decanediol diallyl ether, 1,12-dodecanediol diallyl ether, 1,4-cyclohexanedimethanol diallyl ether, dicyclopentadiene dimethanol diallyl ether, tricyclodecanedimethanol diallyl ether, dipropylene glycol diallyl ether, tripropylene glycol diallyl ether, tetrapropylene glycol diallyl ether, glycerin triallyl ether, PO-modified glycerin triallyl ether, trimethylolpropane triallyl ether, EO-modified trimethylolpropane triallyl ether, PO-modified trimethylolpropane triallyl ether, pentaerythritol tetraallyl ether, PO-modified pentaerythritol tetraallyl ether, ditrimethylolpropane tetraallyl ether, and PO-modified ditrimethylolpropane tetraallyl ether.

[0025] The ink tack reducing agent of the present invention is used in lithographic printing. Among lithographic printing methods, it is preferably used in waterless lithographic printing, which uses a waterless lithographic printing plate as the printing plate, from the viewpoint of further suppressing misalignment and improving registration accuracy by reducing ink tack. In particular, when using a waterless lithographic printing plate having a silicone rubber layer as an ink repulsion layer, it is more preferably used because, in addition to improving registration accuracy by reducing ink tack, it can also further suppress background staining.

[0026] The active energy ray curable ink for lithographic printing according to the present invention (hereinafter sometimes abbreviated as "ink") comprises (a) a resin, (b) a compound having two or more (meth)acryloyl groups in its molecule, and (c) an ink tack reducing agent. By including the polymeric resin (a), the ink can be made highly viscous, further suppressing background staining. In addition, the ink film after curing becomes less brittle. Furthermore, if the ink contains the pigment (d) described later, its dispersion stability can also be improved. By including the compound (b) having two or more (meth)acryloyl groups in its molecule, the ink can be adjusted to a viscosity suitable for lithographic printing. In addition, high-speed curing by irradiation with active energy rays becomes possible. Furthermore, by including the aforementioned ink tack reducing agent (c), when the ink comes into contact with the ink repulsion layer, the ink tack reducing agent (c) migrates and diffuses to the surface of the ink repulsion layer, covering the surface of the ink repulsion layer in a thin film, thereby reducing ink tack and suppressing background staining during printing.

[0027] In this invention, when describing the content of each component in the ink, if the ink contains water and / or solvents, the mass of the contents excluding them shall be used as the basis (100% by mass).

[0028] (a) The resin preferably has hydrophilic groups in its molecules. (a) When the resin has hydrophilic groups, if the ink contains the pigment (d) described later, it stabilizes the dispersion of the pigment (d) in the ink, maintains the viscosity of the ink even under high shear, and further suppresses background staining.

[0029] Examples of hydrophilic groups include hydroxyl groups, amino groups, mercapto groups, carboxyl groups, sulfo groups, and phosphate groups. Among these, (d) carboxyl groups and hydroxyl groups are particularly preferred because they provide good pigment dispersibility.

[0030] Examples of the (a) resin having hydrophilic groups include those exemplified as resins having hydrophilic groups in Japanese Patent Publication No. 2021-98773. The acid value, hydroxyl value, weight-average molecular weight, structure, and iodine value are also preferably within the ranges specified as preferred in Japanese Patent Publication No. 2021-98773. Specifically, (meth)acrylic acid copolymers, (meth)acrylic acid-(meth)acrylic acid ester copolymers, styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, styrene-maleic acid copolymers, styrene-maleic acid-(meth)acrylic acid copolymers, and styrene-maleic acid-(meth)acrylic acid ester copolymers are preferred.

[0031] The content of (a) resin in the ink according to the present invention is preferably 5% by mass or more and 40% by mass or less, from the viewpoint of further improving the dispersibility of (d) pigment and further suppressing background staining.

[0032] (b) The compound having two or more (meth)acryloyl groups in its molecule preferably includes (bi) a compound having two or more (meth)acryloyl groups in its molecule and having a hydrophilic group (hereinafter sometimes abbreviated as "(bi) compound") and (b-ii) a compound having two or more (meth)acryloyl groups in its molecule and not having a hydrophilic group (hereinafter sometimes abbreviated as "(b-ii) compound"). By including the (bi) compound, when the ink contains the (d) pigment described later, the (d) pigment in the ink is dispersed and stabilized, the viscosity of the ink is maintained even under high shear, and background staining can be further suppressed. Furthermore, by including the (b-ii) compound, the wettability to the printing medium can be improved and adhesion can be increased. In addition, since the (b-ii) compound has polarity between the highly polar (bi) compound and the low polarity (c) ink tack reducing agent, the elution of the (c) ink tack reducing agent from the ink can be further suppressed and storage stability can be improved.

[0033] Examples of hydrophilic groups in the (bi) compound include monovalent groups such as carboxyl groups, hydroxyl groups, amino groups, and sulfonic acid groups, and divalent linking groups such as (poly)ethylene oxide linking groups. Two or more of these may be present. Among these, hydroxyl groups, which have particularly high hydrophilicity, are preferred.

[0034] The (bi) compound is preferably one that has high affinity for both the (a) resin and the (b-ii) compound described above, and can dissolve the (a) resin.

[0035] (bi) Examples of compounds include those exemplified in Japanese Patent Publication No. 2021-98773 as (b) polyfunctional (meth)acrylates having hydrophilic groups, and the hydroxyl value, weight-average molecular weight, and structure are preferably within the ranges specified as preferred in Japanese Patent Publication No. 2021-98773, specifically pentaerythritol tri(meth)acrylate, diglycerin tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate.

[0036] The content of the (bi) compound in the ink of the present invention is preferably 10% by mass or more, from the viewpoint of improving the dispersion stability of the (d) pigment and the curability when irradiated with active energy rays. On the other hand, the content of the (bi) compound in the ink of the present invention is preferably 55% by mass or less, from the viewpoint of suppressing the increase in viscosity of the ink due to intermolecular forces between polar groups and maintaining fluidity.

[0037] (b-ii) The compound is preferably one that has high affinity for both the (bi) compound and the (c) ink tack reducing agent mentioned above, and is compatible with these compounds.

[0038] (b-ii) Examples of compounds include 1,4-cyclohexanedimethanol di(meth)acrylate, dicyclopentadiene dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, glycerin tri(meth)acrylate, PO-modified glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate. Examples include acrylate, PO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, PO-modified pentaerythritol tetra(meth)acrylate, diglycerin tetra(meth)acrylate, PO-modified diglycerin tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, PO-modified ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and PO-modified dipentaerythritol hexa(meth)acrylate. Two or more of these may be included.

[0039] The content of compound (b-ii) in the ink of the present invention is preferably 5% by mass or more, from the viewpoint of improving the storage stability of the ink and its adhesion to plastic films and the like. On the other hand, the content of compound (b-ii) in the ink of the present invention is preferably 50% by mass or less, from the viewpoint of suppressing the decrease in viscosity of the ink and further suppressing background staining.

[0040] (c) The ink tack reducing agent preferably has a moderately low affinity for (a) resins and (bi) compounds, which suppresses entanglement of molecular chains in the ink and can further reduce ink tack. On the other hand, (c) the ink tack reducing agent preferably has a high affinity for (b-ii) compounds and is compatible with them.

[0041] The content of (c) ink tack reducing agent in the ink of the present invention is preferably 0.5% by mass or more, more preferably 2% by mass or more, and even more preferably 3.5% by mass or more, from the viewpoint of further reducing ink tack. On the other hand, the content of (c) ink tack reducing agent in the ink of the present invention is preferably 20% by mass or less, and more preferably 15% by mass or less, from the viewpoint of maintaining an appropriate level of ink tack to further suppress background staining, and from the viewpoint of maintaining an appropriate level of affinity with (a) resin and (b) compound to improve the storage stability of the ink.

[0042] The ink according to the present invention may further contain (d) a pigment. By including (d) a pigment, a desired color can be imparted to the ink. Examples of (d) pigments include those exemplified as pigments in Japanese Patent Application Publication No. 2021-98773.

[0043] If the ink of the present invention contains (d) pigment, the content is preferably 15% by mass or more if it is an organic pigment or carbon black with a specific gravity of 2 or less, and preferably 40% by mass or more if it is an inorganic pigment with a specific gravity greater than 2, from the viewpoint of improving print density. On the other hand, the content of (d) pigment in the ink of the present invention is preferably 40% by mass or less if it is an organic pigment or carbon black with a specific gravity of 2 or less, and preferably 50% by mass or less if it is an inorganic pigment with a specific gravity greater than 2, from the viewpoint of improving ink fluidity and transferability.

[0044] The ink according to the present invention may (d) not contain a pigment. If (d) it does not contain a pigment, it is transparent and can be used, for example, as an overcoat varnish.

[0045] The ink according to the present invention may further contain a photoradical polymerization initiator and a sensitizer. By including a photoradical polymerization initiator, the ink can be cured even when ultraviolet light is used as the active energy ray. Furthermore, by including a sensitizer, sensitivity is improved, and the ink can be cured with a smaller amount of ultraviolet exposure.

[0046] Examples of photoradical polymerization initiators include those exemplified in (e) Photopolymerization Initiator in Japanese Patent Publication No. 2018-188671.

[0047] If the ink of the present invention contains a photoradical polymerization initiator, its content is preferably 2% by mass or more from the viewpoint of improving sensitivity to ultraviolet light. On the other hand, the content of the photoradical polymerization initiator in the ink of the present invention is preferably 20% by mass or less from the viewpoint of improving the storage stability of the ink and maintaining good fluidity.

[0048] Examples of sensitizers include those exemplified as sensitizers in Japanese Patent Publication No. 2021-98773.

[0049] If the ink according to the present invention contains a sensitizer, its content is preferably 2% by mass or more from the viewpoint of improving sensitivity. On the other hand, the content of the sensitizer in the ink according to the present invention is preferably 10% by mass or less from the viewpoint of improving the storage stability of the ink.

[0050] Furthermore, when (c) a compound having two or more alkenyl ether groups in the molecule is used as an ink tack reducing agent, it is also preferable to include a photocationic polymerization initiator in addition to the above-mentioned photoradical polymerization initiator, which can accelerate the curing reaction. Examples of photocationic polymerization initiators include the triarylsulfonium complex salt described in U.S. Patent No. 4,231,951, the aromatic sulfonium salt or aromatic iodonium salt of a halogen-containing complex ion described in U.S. Patent No. 4,256,828; the aromatic onium salt of a group VIa element described in U.S. Patent No. 4,058,401 and No. 4,138,255; and the aromatic onium salt of a group Va element described in U.S. Patent No. 4,069,055.

[0051] If the ink of the present invention contains a photocationic polymerization initiator, its content is preferably 2% by mass or more from the viewpoint of improving sensitivity to ultraviolet light. On the other hand, the content of the photocationic polymerization initiator in the ink of the present invention is preferably 15% by mass or less from the viewpoint of improving the storage stability of the ink and maintaining good fluidity. However, as will be described later, in applications such as food packaging, it is also preferable for the ink to be substantially free of the photocationic polymerization initiator.

[0052] The ink according to the present invention may contain polymerization inhibitors. Examples of polymerization inhibitors include hydroquinone, hydroquinone monoesters, N-nitrosodiphenylamine, phenothiazine, pt-butylcatechol, N-phenylnaphthylamine, 2,6-di-t-butyl-p-methylphenol, chloranyl, and pyrogallol. Two or more of these may be included.

[0053] If the ink of the present invention contains a polymerization inhibitor, its content is preferably 0.001% by mass or more from the viewpoint of improving storage stability, and preferably 5% by mass or less from the viewpoint of improving sensitivity.

[0054] The ink according to the present invention may contain (e) a pigment dispersant to improve the dispersibility of the pigment. The optimal amount of (e) pigment dispersant varies depending on the density, particle size, surface area, etc., of the (d) pigment used, but (e) the pigment dispersant acts on the surface of the (d) pigment and suppresses the aggregation of the pigment. This improves the dispersibility of the pigment and can improve the fluidity of the ink according to the present invention.

[0055] (e) Examples of pigment dispersants include those exemplified as pigment dispersants in Japanese Patent Publication No. 2021-98773.

[0056] If the ink of the present invention contains (e) a pigment dispersant, the amount thereof is preferably 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of (d) pigment, from the viewpoint of improving the fluidity of the ink.

[0057] The ink according to the present invention may further contain additives such as wax, defoaming agents, transferability enhancers, and leveling agents, as needed.

[0058] In applications where the migration and elution of unreacted components and the suppression of odors are particularly important, the ink of the present invention preferably contains substantially no photocationic polymerization initiator. Here, "substantially contained" means that the content of photocationic polymerization initiator in the ink is less than 0.5% by mass. Examples of such applications include food packaging. In such applications, it is also preferable that the above-mentioned photoradical polymerization initiator and sensitizer also contain substantially no photocationic polymerization initiator.

[0059] The ink of the present invention is used in lithographic printing. Among lithographic printing methods, it is preferably used in waterless lithographic printing, which uses a waterless lithographic printing plate as the printing plate, from the viewpoint of further suppressing misalignment by reducing ink tack and further improving registration accuracy. In particular, when using a waterless lithographic printing plate having a silicone rubber layer as an ink repulsion layer, it is more preferably used because, in addition to improving registration accuracy by reducing ink tack, it is also possible to further suppress background smudging.

[0060] The ink tack of the ink of the present invention can be measured using an incometer. More specifically, 1.31 ml of ink is weighed using an ink pipette, and the ink tack is measured using an incometer at a rotation speed of 400 rpm and a temperature of 38°C. In this invention, the value obtained 1 minute after the start of measurement is defined as the ink tack.

[0061] Next, a method for manufacturing the ink according to the present invention will be described. Examples of the ink according to the present invention include a method in which (a) a resin is dissolved in (b) a compound having two or more (meth)acryloyl groups in its molecule at a temperature range of 5 to 100°C, (d) a pigment and other components are added and homogeneously mixed and dispersed, and (c) an ink tack reducing agent is added and further mixed until uniform, or a method in which (a) a resin is dissolved in (b) a compound having two or more (meth)acryloyl groups in its molecule and (c) an ink tack reducing agent at a temperature range of 5 to 100°C, and then (d) a pigment and other components are added and homogeneously mixed and dispersed. Examples of mixing and dispersion equipment include kneaders, three-roll mills, ball mills, planetary ball mills, bead mills, roll mills, attritors, sand mills, gate mixers, paint shakers, homogenizers, and other agitators and kneaders. When (c) an ink tack reducing agent is added to the ink, it may be mixed manually using a spatula or the like. Degassing under vacuum or reduced pressure conditions is also preferably performed after mixing and dispersion or during the mixing and dispersion process.

[0062] Next, a method for manufacturing printed materials using the ink according to the present invention will be described. One embodiment of the method for manufacturing printed materials according to the present invention includes the steps of transferring the ink according to the present invention to a printing medium and irradiating the transferred active energy ray-curable ink for lithographic printing with active energy rays. In another embodiment of the method for manufacturing printed materials according to the present invention, if an ink that does not contain (c) an ink tack reducing agent is used instead of the ink according to the present invention, then in the step of transferring the ink to the printing medium, if lithographic printing is used, the (c) ink tack reducing agent of the present invention may be applied to the lithographic printing plate in advance. In this case, the (c) ink tack reducing agent may be dissolved or dispersed in a solvent such as water or an organic solvent and then applied.

[0063] First, the process of transferring the ink according to the present invention to the printing medium will be described.

[0064] Examples of printing media include art paper, coated paper, cast paper, synthetic paper, newsprint, plastic film, plastic film laminated paper, metal plates, metal-deposited paper, and metal-deposited plastic film. Examples of plastic films include films made from plastics such as polyethylene terephthalate, polyethylene, polyester, polyamide, polyimide, polystyrene, polypropylene, polycarbonate, and polyvinyl acetal. Examples of plastic film laminated paper include those in which the aforementioned plastic film is laminated on paper. Examples of metal plates include plates made from metals such as aluminum, zinc, and copper. Examples of metal-deposited paper and metal-deposited plastic film include those in which the aforementioned metal or its oxide is deposited on paper or plastic. Among these, plastic film, plastic film laminated paper, and metal-deposited plastic film do not absorb ink and therefore do not fix the ink by absorption, making them suitable for use in the method of manufacturing printed materials of the present invention, which allows the ink to be cured and fixed by irradiation with active energy rays.

[0065] The printing medium may be treated with an easy-adhesion treatment, which can further improve ink transfer to the printing medium. Examples of easy-adhesion treatments include surface treatments such as primer application, corona discharge treatment, and plasma treatment, as well as the formation of an easy-adhesion layer.

[0066] The thickness of the substrate is preferably 5 μm or more, and more preferably 10 μm or more, from the viewpoint of improving mechanical strength and further improving registration accuracy. On the other hand, the thickness of the substrate is preferably 50 μm or less, and more preferably 30 μm or less, from the viewpoint of reducing the amount of substrate used.

[0067] Both sheet-fed and roll-film materials can be used as the printing medium. When using thin film for flexible packaging applications, it is preferable to use roll-film and transfer the image using a roll-to-roll method.

[0068] Methods for transferring ink to a printing medium according to the present invention include flexographic printing, lithographic printing, gravure printing, and screen printing. Lithographic printing methods include lithographic offset printing, in which ink on a lithographic printing plate is transferred to the printing medium via a blanket, and lithographic direct printing, in which ink on a lithographic printing plate is transferred directly to the printing medium without the use of a blanket. In the present invention, lithographic printing, i.e., lithographic offset printing and lithographic direct printing, is preferred, and either watered printing or waterless printing methods can be used. As mentioned above, from the viewpoint of further improving registration accuracy by reducing ink tack, waterless lithographic printing, which uses a waterless lithographic printing plate as the lithographic printing plate used for printing, is more preferable. In particular, when using a waterless lithographic printing plate having a silicone rubber layer as an ink repulsion layer, it is more preferable to use it because, in addition to improving registration accuracy by reducing ink tack, background staining can be further suppressed.

[0069] Next, we will explain the process of irradiating with active energy rays.

[0070] The ink according to the present invention can instantly harden the ink coating on printed materials by irradiation with an active energy ray. Any active energy ray that has the excitation energy necessary for the hardening reaction can be used, and for example, ultraviolet (UV) light and electron beams (EB) are preferably used. Examples of ultraviolet irradiation devices include high-pressure mercury lamps, xenon lamps, metal halide lamps, and light-emitting diodes (LEDs). Using ultraviolet light (LED-UV) from a light-emitting diode that emits emission lines with a wavelength of 350 to 420 nm is preferable from the viewpoint of saving power. As for electron beam irradiation devices, electron beam devices having energy lines of 100 to 500 eV are preferably used. When obtaining printed materials for food packaging, it is preferable to irradiate with an electron beam. By using an electron beam, inks that substantially do not contain the aforementioned photoradical polymerization initiators, sensitizers, and photocationic polymerization initiators can also be sufficiently hardened, thereby suppressing the migration, elution, and odor of components derived from their decomposition products.

[0071] The thickness of the ink coating (cured ink film) on the printed material is preferably 0.1 to 50 μm. By keeping the ink coating thickness within this range, it is possible to reduce the amount of ink used while maintaining good print quality. [Examples]

[0072] The present invention will be described in more detail below with reference to examples. Measurements and evaluations in each example and comparative example were performed by the following methods.

[0073] (1) Compatibility of ink tack reducing agents with dimethyl silicone oil (1-1) Kinematic viscosity at 25°C is 50 mm 2 Compatibility of / s with dimethyl silicone oil In a temperature-controlled room at 25°C, 30 ml of KF-96-50cs was placed in a glass screw-cap bottle: "Laboran®" Pack Screw-Cap Bottle No. 8 (volume: 110 ml, manufactured by AS ONE Corporation). Then, 3 ml of the ink tack reducing agent used in each example and comparative example was added, the bottle was sealed, and after shaking vigorously by hand for 5 minutes, it was allowed to stand. If no turbidity was observed by visual inspection of the mixture, or if turbidity was observed but no clear phase separation (phase interface) was observed after standing for 7 days, it was judged to be "mismatched." If a clear phase separation (phase interface) was observed by visual inspection of the mixture, or if turbidity was observed but a clear phase separation (phase interface) was observed after standing for 7 days, it was judged to be "mismatched." When KF-96-50cs and the ink tack reducing agent were compatible, compatibility was evaluated by repeatedly adding 3 ml at a time, up to a maximum of 63 ml, until the ink tack reducing agent could no longer be compatible, stirring, and allowing it to stand, observing for turbidity and phase separation each time. By converting 30 ml to 100 parts by volume, the kinematic viscosity at 25°C was 50 mmHg. 2 The compatibility of an ink tack reducing agent with dimethyl silicone oil at / s was calculated.

[0074] (1-2) The kinematic viscosity at 25°C is 5,000 mm². 2 Compatibility of / s with dimethyl silicone oil In a temperature-controlled room at 25°C, 30 ml of KF-96-5,000cs was placed in a “Laboran®” screw-cap vial No. 8. Then, 3 ml of the ink tack reducing agent used in each example and comparative example was added, the vial was sealed, and after shaking vigorously by hand for 5 minutes, it was allowed to stand. In the same manner as in (1-1) above, it was determined whether or not the mixture was miscible. If KF-96-5,000cs and the ink tack reducing agent were miscible, the miscibleness was evaluated by repeatedly adding 3 ml at a time, up to a maximum of 63 ml, stirring and standing until the ink tack reducing agent was no longer miscible, and checking for turbidity and phase separation each time. Converting 30 ml to 100 parts by volume, the kinematic viscosity at 25°C was 5,000 mm². 2 The compatibility of an ink tack reducing agent with dimethyl silicone oil at / s was calculated.

[0075] (2) InkTac (2-1) Ink tack before EPDM contact 1.31 ml of the active energy ray-curable ink for lithographic printing obtained in each example and comparative example was weighed using an ink pipette, and the ink tack was measured using an Incometer (INKO-GRAPH TYPE V, manufactured by Tester Industries Co., Ltd.) at a rotation speed of 400 rpm and 38°C. The value obtained 1 minute after the start of measurement was defined as the ink tack in the present invention.

[0076] (2-2) Ink tack after EPDM contact A variable offset rotary printing press (MHL13A, manufactured by Miyakoshi Co., Ltd.) equipped with an EPDM inking roller (WERO-UV D407-01, manufactured by Westland Gummiwerke GmbH & Co.KG) in the inking unit was fitted with 50g of the active energy ray curable ink for lithographic printing obtained in each example and comparative example. The press was operated for 5 minutes without the ink fountain and plate cylinder in contact with the inking unit, allowing the active energy ray curable ink for lithographic printing to spread uniformly on each roller of the inking unit. After 5 minutes, the operation of the inking unit was stopped, and it was left to stand for 3 hours. After 3 hours, the ink adhering to the EPDM part of the WERO-UV D407-01 was collected, and the ink tack of the collected active energy ray curable ink for lithographic printing was measured using the same procedure as in (2-1) above.

[0077] (3) Amount of unreacted components to be eluted A waterless lithographic printing plate ("Toray Waterless CTP Lithographic Plate (Registered Trademark)": TAC-VG5 (manufactured by Toray Industries, Inc.)) with a 472mm x 350mm silicone rubber layer as an ink-rebound layer, and a strip-shaped solid image measuring 280mm x 280mm in the center, was mounted on the plate cylinder of an MHL13A printer. Printing was then performed using the activated energy ray-curable inks for lithographic printing obtained in each example and comparative example, under the following printing / ink curing conditions.

[0078] <Printing Conditions> Inking roller: WERO-UV D407-01 Blanket: T626 (manufactured by Kinyo Co., Ltd.) Printed medium: “Embret (registered trademark)” PTM-12 (rolled biaxially stretched PET film, thickness: 12 μm, printing surface: easy adhesion treatment, manufactured by Unitika Ltd.) Plate surface temperature: 28 ± 2°C Ink feed volume: Adjusted so that the thickness of the ink film after curing is 3.0 ± 0.1 μm Printing speed: 100 m / min <Ink Curing Conditions> <LED-UV (performed in Examples 1 to 2)> Wavelength: 385 nm Integrated light quantity: 150 mJ / cm 2 Irradiation atmosphere: Atmospheric atmosphere <EB (performed in Examples 3 to 18 and Comparative Examples 1 to 5)> Accelerating voltage: 110 kV Irradiation dose: 40 kGy Irradiation atmosphere: Nitrogen atmosphere.

[0079] Cut out the printed matter at the 1,000 m printing point, cut the cured ink film part of the solid part into a 12 cm square, set it in a cylindrical single-sided elution device with an evaluation area of 100 cm 2 so that the printing surface becomes the elution surface, then inject 100 ml of 95% by mass ethanol and store it in a constant temperature bath at 60°C for 5 hours. Then, concentrate the ethanol by 10 times and measure the amount of ink components (unreacted components) eluted in the ethanol by liquid chromatography mass spectrometry (LC-MS).

[0080] (4) Odor of Printed Matter Printing was performed in the same manner as described in (3) above for evaluating the amount of unreacted components eluted, except that the ink feed rate was adjusted so that the reflectance density of the solid areas was 1.60 ± 0.05. A sample of the printed material was cut out at the 1,000m printing stage, and the presence or absence of odor was evaluated by a sensory test. Five different people smelled the hardened ink film portion (solid area) of the printed material, and the number of people who detected an odor was counted. The fewer the number of people who detected an odor, the less odor there was, and if 0 people detected an odor, it was considered odorless.

[0081] (5) Ground stains The printout used in the evaluation of the odor of the printed material in (4) above, at the 1,000m printing stage, was placed on a stack of five sheets of coated paper: OK "Topcoat (registered trademark)"+ (manufactured by Oji Paper Co., Ltd.), and the reflectance density of the non-image area located 10mm below the solid area in the printing direction from the center in the width direction was measured using a spectrophotometer: Exact Advance (manufactured by X-Rite). For reference, the reflectance density of the paper white was set as 0.00 when an unprinted "Emblet (registered trademark)" PTM-12 was placed on top of the stack of five sheets of OK "Topcoat (registered trademark)"+ and the reflectance density measured from the "Emblet (registered trademark)" PTM-12 side was placed. The lower the reflectance density, the more the background staining is suppressed.

[0082] [Example 1] In a separable flask, (a-1), (b-1), and (b-2) were added and heated at 95°C for 390 minutes while stirring with a disperser blade at a rotation speed of 500 rpm to obtain varnish. To the obtained varnish, (d-1), (e-1), (f-1), and (g-1) were added and kneaded five times through a gap of 1 using a three-roll mill: "EXAKT®" M-80S (manufactured by EXAKT). (a-1) Resin: 20 parts by mass of a resin having ethylenically unsaturated groups and carboxyl groups, obtained by adding 0.55 equivalents of glycidyl methacrylate to the carboxyl group of a copolymer obtained from 25% by mass of methyl methacrylate, 25% by mass of styrene, and 50% by mass of methacrylic acid, with a weight-average molecular weight of 34,000, an acid value of 105 mgKOH / g, and an iodine value of 2.0 mol / kg. (b-1) Compounds having two or more (meth)acryloyl groups in the molecule: A mixture of pentaerythritol triacrylate ((bi) compound) and pentaerythritol tetraacrylate ((b-ii) compound) "Miramer" (registered trademark) M340 (hydroxyl group: present, hydroxyl value: 115 mg KOH / g, pentaerythritol triacrylate content: 61% by mass, manufactured by MIWON): 21 parts by mass (b-2) Compounds having two or more (meth)acryloyl groups in the molecule: Tricyclodecanedimethanol diacrylate ((b-ii) compound) “Miramer” (registered trademark) M262 (hydroxyl group: none, hydroxyl value: 0 mgKOH / g, manufactured by MIWON): 21 parts by mass (d-1) Pigment: Seica Cyanine Blue 4920 (manufactured by Dainichi Seika Co., Ltd.): 20 parts by mass (e-1) Photoradical polymerization initiator: "Irgacure" (registered trademark) 819 (manufactured by BASF): 4.9 parts by mass (f-1) Photocationic polymerization initiator: CPI-110P (manufactured by Sunapro Co., Ltd.): 3 parts by mass (g-1) Polymerization inhibitor: p-methoxyphenol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): 0.1 parts by mass.

[0083] To the resulting mixture, 10 parts by mass of (c-1) ink tack reducing agent: DCDVE (1,10-decanediol divinyl ether, manufactured by Nippon Carbide Industries Co., Ltd.) were added and thoroughly mixed with a spatula to obtain active energy ray curable ink-1 for lithographic printing.

[0084] [Example 2] Active energy ray curable ink-2 for lithographic printing was obtained by the same procedure as in Example 1, except that (b-1) and (b-2) were both changed to 22.5 parts by mass, and (f-1) was changed to 0 parts by mass.

[0085] [Example 3] In a separable flask, (a-1), (b-1), and (b-2) were added and heated at 95°C for 390 minutes while stirring with a disperser blade at a rotation speed of 500 rpm to dissolve and obtain varnish. To the obtained varnish, (d-1) was added and kneaded five times through a gap of 1 using an "EXAKT®" M-80S. (a-1) 20 parts by mass of a resin having ethylenically unsaturated groups and carboxyl groups, obtained by adding 0.55 equivalents of glycidyl methacrylate to the carboxyl group of a copolymer obtained from 25% by mass of methyl methacrylate, 25% by mass of styrene, and 50% by mass of methacrylic acid, with a weight-average molecular weight of 34,000, an acid value of 105 mgKOH / g, and an iodine value of 2.0 mol / kg. (b-1) “Miramer (registered trademark)” M340: 25 parts by mass (b-2) “Miramer (registered trademark)” M262: 25 parts by mass (d-1) Seika Cyanine Blue 4920: 20 parts by mass.

[0086] To the resulting mixture, 10 parts by mass of (c-1)DCDVE were added and thoroughly mixed with a spatula to obtain lithographic active energy ray curable ink-3.

[0087] [Example 4] Active energy ray curable ink-4 for lithographic printing was obtained by the same procedure as in Example 3, except that (c-1) was changed to (c-2) ink tack reducing agent: CHDVE (1,4-cyclohexanedimethanol divinyl ether, manufactured by Nippon Carbide Industries, Ltd.).

[0088] [Example 5] Active energy ray curable ink-5 for lithographic printing was obtained by the same procedure as in Example 3, except that (c-1) was changed to (c-3) ink tack reducing agent represented by the following general formula (I): PO-modified trimethylolpropane trivinyl ether (manufactured by Nippon Carbide Industries Co., Ltd.).

[0089] [ka]

[0090] [Example 6] Active energy ray curable ink-6 for lithographic printing was obtained by the same procedure as in Example 3, except that (c-1) was changed to (c-4) ink tack reducing agent: pentaerythritol tetraallyl ether (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0091] [Example 7] Except for changing (c-1) to (c-5), an ink tack reducing agent represented by the following general formula (II): EO-modified trimethylolpropane trivinyl ether (manufactured by Nippon Carbide Industries Co., Ltd.), an active energy ray curable ink-7 for lithographic printing was obtained by the same procedure as in Example 3.

[0092] [ka]

[0093] [Example 8] In a separable flask, (a-1), (b-1), (b-2), and (c-1) were added and heated at 95°C for 390 minutes while stirring with a disperser blade at a rotation speed of 500 rpm to dissolve and obtain varnish. To the obtained varnish, (d-1) was added and kneaded five times through gap 1 using "EXAKT®" M-80S to obtain active energy ray curable ink-8 for lithographic printing. (a-1) 20 parts by mass of a resin having ethylenically unsaturated groups and carboxyl groups, obtained by adding 0.55 equivalents of glycidyl methacrylate to the carboxyl group of a copolymer obtained from 25% by mass of methyl methacrylate, 25% by mass of styrene, and 50% by mass of methacrylic acid, with a weight-average molecular weight of 34,000, an acid value of 105 mgKOH / g, and an iodine value of 2.0 mol / kg. (b-1) “Miramer” (registered trademark) M340: 29.75 parts by mass (b-2) “Miramer” (registered trademark) M262: 29.75 parts by mass (c-1)DCDVE: 0.5 parts by mass (d-1) Seika Cyanine Blue 4920: 20 parts by mass.

[0094] [Examples 9-14] Active energy ray curable inks for lithographic printing, 9 to 14, were obtained using the same procedure as in Example 8, except that the amounts of (b-1), (b-2), and (c-1) added were changed as shown in Table 2.

[0095] [Example 15] Active energy ray curable ink-15 for lithographic printing was obtained by the same procedure as in Example 13, except that (c-1) was changed to (c-3).

[0096] [Example 16] Active energy ray curable ink-16 for lithographic printing was obtained by the same procedure as in Example 14, except that (c-1) was changed to (c-3).

[0097] [Example 17] Active energy ray curable ink-17 for lithographic printing was obtained by the same procedure as in Example 13, except that (c-1) was changed to (c-4).

[0098] [Example 18] Active energy ray curable ink-18 for lithographic printing was obtained by the same procedure as in Example 14, except that (c-1) was changed to (c-4).

[0099] [Comparative Example 1] In a separable flask, (a-1), (b-1), and (b-2) were added and heated at 95°C for 390 minutes while stirring with a disperser blade at a rotation speed of 500 rpm to dissolve and obtain varnish. To the obtained varnish, (d-1) was added and kneaded five times through gap 1 using "EXAKT®" M-80S to obtain active energy ray curable ink-19 for lithographic printing. Active energy ray curable ink-19 for lithographic printing does not contain an ink tack reducing agent. (a-1) 20 parts by mass of a resin having ethylenically unsaturated groups and carboxyl groups, obtained by adding 0.55 equivalents of glycidyl methacrylate to the carboxyl group of a copolymer obtained from 25% by mass of methyl methacrylate, 25% by mass of styrene, and 50% by mass of methacrylic acid, with a weight-average molecular weight of 34,000, an acid value of 105 mgKOH / g, and an iodine value of 2.0 mol / kg. (b-1) “Miramer (registered trademark)” M340: 30 parts by mass (b-2) “Miramer (registered trademark)” M262: 30 parts by mass (d-1) Seika Cyanine Blue 4920: 20 parts by mass.

[0100] [Comparative Example 2] Active energy ray curable ink-20 for lithographic printing was obtained by the same procedure as in Example 12, except that (c-1) was changed to (c-6) ink tack reducing agent: NK ester A-DOD-N (1,10-decanediol diacrylate, manufactured by Shin Nakamura Chemical Industry Co., Ltd.).

[0101] [Comparative Example 3] Active energy ray curable ink-21 for lithographic printing was obtained by the same procedure as in Example 12, except that (c-1) was changed to (c-7) ink tack reducing agent: 1,12-dodecanediol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0102] [Comparative Example 4] Active energy ray curable ink-22 for lithographic printing was obtained by the same procedure as in Example 12, except that (c-1) was changed to (c-8) ink tack reducing agent: LA (lauryl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.).

[0103] [Comparative Example 5] Active energy ray curable ink-23 for lithographic printing was obtained by the same procedure as in Example 12, except that (c-1) was changed to (c-9) ink tack reducing agent: ISTA (isostearyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.).

[0104] Tables 1-3 show the ink composition and evaluation results for Examples 1-18 and Comparative Examples 1-5.

[0105] [Table 1]

[0106] [Table 2]

[0107] [Table 3]

Claims

1. An active energy ray curable ink tack reducing agent for lithographic printing, comprising a compound having the characteristics of (1) and (2) below. (1) The molecule contains two or more ethylenically unsaturated double bonds. (2) Kinematic viscosity at 25°C is 50 mm ２ It is miscible at 25°C with 30 parts by volume or more of dimethyl silicone oil at 100 parts by volume.

2. The active energy ray curable ink tack reducing agent for lithographic printing according to claim 1, wherein the compound further has the following (3) characteristics. (3) The kinematic viscosity at 25°C is 5,000 mm². ２ At 25°C, it does not miscible in more than 200 parts by volume with 100 parts by volume of dimethyl silicone oil at / s.

3. The active energy ray curable ink tack reducing agent for lithographic printing according to claim 1 or 2, wherein the ethylenically unsaturated double bond in (1) is derived from an alkenyl ether group.

4. The active energy ray curable ink tack reducing agent for lithographic printing according to claim 3, wherein the alkenyl ether group is a vinyl ether group.

5. The active energy ray curable ink tack reducing agent for lithographic printing according to claim 1 or 2, wherein the active energy ray curable ink for lithographic printing is a waterless active energy ray curable ink for lithographic printing.

6. A lithographic active energy ray-curable ink comprising (a) a resin, (b) a compound having two or more (meth)acryloyl groups in its molecule, and (c) the active energy ray-curable ink tack reducing agent for lithographic printing described in claim 1 or 2.

7. The active energy ray curable ink for lithographic printing according to claim 6, comprising 0.5 to 20% by mass of the active energy ray curable ink tack reducing agent for lithographic printing according to claim 1 or 2.

8. The active energy ray curable ink for lithographic printing according to claim 6, which substantially does not contain a photocationic polymerization initiator.

9. The active energy ray curable ink for lithographic printing according to claim 6, wherein the active energy ray curable ink for lithographic printing is a waterless active energy ray curable ink for lithographic printing.

10. A method for manufacturing a printed material, comprising the steps of transferring the active energy ray-curable ink for lithographic printing described in claim 6 to a printing medium using a lithographic printing plate, and irradiating the transferred active energy ray-curable ink for lithographic printing with active energy rays.

11. The method for manufacturing a printed article according to claim 10, wherein the lithographic printing plate is a waterless lithographic printing plate having a silicone rubber layer as an ink repulsion layer.

12. The method for manufacturing a printed article according to claim 10, wherein the average thickness of the printing medium is 50 μm or less.

13. The method for manufacturing a printed article according to claim 10, wherein the active energy ray is an electron beam.

14. The method for manufacturing a printed material according to claim 10, wherein the printed material is for food packaging.

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