JP6628760B2 - Active energy ray-curable inkjet ink composition - Google Patents

Description

  The present invention relates to an active energy ray-curable inkjet ink composition, and more particularly to an active energy ray-curable inkjet ink composition having excellent wettability and re-discharge properties.

  In recent years, many active energy ray-curable inks have been proposed as inks used for inkjet printing. Active energy ray-curable inks are cured by irradiation with active energy rays such as ultraviolet rays, so that steps such as volatilization and drying of water and organic solvents performed in the case of conventional organic solvent-based inks and water-based inks are unnecessary, Further, since it is quick-drying, there is an advantage that productivity of printed matter can be improved. However, on the other hand, there is also a problem that it is difficult to obtain sufficient wettability to the printing surface, and a method for addressing such a problem is being studied.

  Japanese Patent Application Laid-Open No. 2008-207528 (Patent Document 1) discloses a process of performing a wettability improving process selected from the group consisting of a plasma process, a corona process, and a frame process on an ink-applied surface. Describes a method for producing a colored product in which the process of applying an ultraviolet-curable ink and the process of irradiating the applied ultraviolet-curable ink with ultraviolet light are repeated.

  Japanese Patent Application Laid-Open No. 2010-112073 (Patent Document 2) discloses a building board having a base material having an undercoat layer and a UV ink image layer in contact with the undercoat layer. The paint is a acrylic resin emulsion with a calculated glass transition point Tg of 35 to 90 ° C, and describes a building board that contains a wetting agent in the UV ink of the UV ink image layer.

  The methods described in Patent Literatures 1 and 2 improve the printing surface of the active energy ray-curable ink to cover the low wettability of the ink.

  On the other hand, JP-A-2015-67765 (Patent Document 3) includes a radical polymerizable monomer (A) having 1 to 2 functional groups, a photopolymerization initiator (B), and an acrylic surface conditioner (C). Describe an active energy ray-curable inkjet ink composition characterized by that, by blending the acrylic surface conditioner, the wettability of the ink to a hydrophilic substrate having a contact angle to water of 60 ° or less, In addition, it describes that the leveling property of the printed matter can be improved.

JP 2012-219255 A (Patent Document 4) discloses that as a polymerizable compound, CH ₂ ＣＲCR ¹ —COOR ² —O—CH ＝ CH—R ³ (wherein R ¹ is a hydrogen atom or a methyl group. , R ² is a divalent organic residue having 2 to 20 carbon atoms, and R ³ is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms. ) Acrylates are contained, and as a surfactant, a polyether-modified silicone oil having a mass average molecular weight of 10,000 to 13,000 and an HLB of 5 to 11 is contained in a specific ratio. Describes an ultraviolet-curable ink composition, in which the use of vinyl ether group-containing (meth) acrylates and polyether-modified silicone oils described herein are preferable for improving wettability. It is that there is.

  Japanese Patent Application Laid-Open No. 2010-235914 (Patent Document 5) discloses an active energy ray-curable inkjet ink containing at least a polymerizable monomer, wherein the polymerizable monofunctional monomer is at least 60% of the total polymerizable monomer. 98% or less, and one of the monofunctional monomers is isobornyl acrylate, containing 25% or more and 65% or less based on the total polymerizable monomer, and one of the monofunctional monomers is N-vinylcaprolactam. Wherein the active energy ray-curable inkjet ink composition contains 12.5% or more and 60% or less with respect to all polymerizable monomers. It has a particularly good affinity for and shows good wet spreadability to various substrates.

JP 2008-207528 A JP 2010-112073 A JP-A-2015-67765 JP 2012-219255 A JP 2010-235914 A

  The ink compositions described in Patent Documents 3 to 5 can be said to be inks having excellent wettability. However, an ink having excellent wettability exhibits good wettability not only on a printing surface but also on an ink jet printer, more specifically, a nozzle head portion thereof. For this reason, if printing is performed intermittently or printing is temporarily interrupted, printing will be performed at a certain time interval due to evaporation of the ink adhering to the head and spreading of the nozzle surface. When restarted, there is a problem that the ink cannot be normally ejected.

  Therefore, an object of the present invention is to solve the above-described problems of the prior art, and even for an active energy ray-curable inkjet ink composition having excellent wettability, when printing is resumed after a certain period of time, the nozzle head section has An object of the present invention is to provide an ink composition capable of normal ejection.

  In the present specification, the property that an image can be printed at a predetermined position even when ink-jet printing is restarted after a certain time has elapsed is referred to as “re-discharge property”. Here, the fixed time until the printing is restarted is assumed to be a time period from 10 minutes to 120 minutes after the ink ejection is stopped until the printing is restarted. For example, if the time interval before resuming printing is shorter than 10 minutes, it is considered that there is no problem of re-ejection even with the conventional ink having excellent wettability. If the time interval until the printing is restarted is longer than 120 minutes, the re-ejection property may be reduced due to volatilization of the active energy ray-curable ink and spreading on the nozzle surface regardless of the wettability. By the way, when the time interval until the printing is resumed is too long and the re-ejection property is reduced, for example, by performing the usual maintenance of the printer head such as forcibly discharging the ink and wiping the ink of the nozzle plate. It is possible to deal with it.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, an active energy ray-curable inkjet ink composition having a low surface tension and a monofunctional monomer having a specific ratio and excellent wettability, the monofunctional monomer was used. It has been found that an active energy ray-curable inkjet ink composition having excellent re-discharge properties can be provided by blending a alkanediol diacrylate in a specific ratio with respect to the monomer and blending a monofunctional monomer having an aromatic ring. Thus, the present invention has been completed.

That is, the active energy ray-curable inkjet ink composition of the present invention is an active energy ray-curable inkjet ink composition containing a radical polymerizable monomer (A) and a photopolymerization initiator (B),
The radical polymerizable monomer (A) is a monomer (A-1) to (A-3) shown below:
(A-1) a monofunctional monomer having a surface tension at 25 ° C of 32 mN / m or less,
(A-2) at least a bifunctional monomer that is an alkanediol diacrylate, and (A-3) a monofunctional monomer having an aromatic ring.
The content of the monomer (A-1) in the ink composition is 5 to 40% by mass, and the mass ratio of the monomer (A-1) to the monomer (A-2) in the ink composition is 2: 1 to 1: 4.

  In a preferable example of the active energy ray-curable inkjet ink composition of the present invention, the content of the monomer (A-1) in the ink composition is 10 to 35% by mass, and the content of the monomer (A-1) in the ink composition is The content of A-2) is 10 to 35% by mass, and the content of the monomer (A-3) in the ink composition is 10 to 25% by mass.

  In another preferred example of the active energy ray-curable inkjet ink composition of the present invention, the mass ratio of the monomer (A-1) to the monomer (A-2) is from 1.5: 1 to 1: 2.

  In another preferred example of the active energy ray-curable inkjet ink composition of the present invention, the total content of the monomer (A-1) and the monomer (A-2) in the ink composition is 30 to 70% by mass. is there.

  In another preferred embodiment of the active energy ray-curable inkjet ink composition of the present invention, the monomer (A-1) is at least selected from the group consisting of alicyclic monofunctional monomers and propylene glycol monofunctional monomers. One kind.

  In another preferred embodiment of the active energy ray-curable inkjet ink composition of the present invention, the monomer (A-2) has 6 to 10 carbon atoms between two acryloyloxy groups.

  In another preferred embodiment of the active energy ray-curable inkjet ink composition of the present invention, the ink composition further includes a radically polymerizable urethane oligomer (C), and the radically polymerizable urethane oligomer (C) in the ink composition. ) Is 5 to 15% by mass.

  In another preferred example of the active energy ray-curable inkjet ink composition of the present invention, the radical polymerizable monomer (A) further includes an alicyclic bifunctional monomer (A-4), and The content of the monomer (A-4) is 5 to 15% by mass.

〔式（１）中、Ｒ^１は、水素原子又は炭素数が１〜８のアルキル基であり、Ｒ^２は、水素原子又はメチル基である〕で表されるモノマー（Ａ−５）を更に含み、前記インク組成物中における単官能モノマー（Ａ−５）の含有量が１〜９質量％である。 In another preferred embodiment of the active energy ray-curable inkjet ink composition of the present invention, the radical polymerizable monomer (A) is represented by the following formula (1):

[In the formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ² is a hydrogen atom or a methyl group.] The content of the monofunctional monomer (A-5) in the ink composition is 1 to 9% by mass.

  ADVANTAGE OF THE INVENTION According to this invention, the active-energy-ray-curable inkjet ink composition which is excellent in wettability and re-discharge property can be provided.

  Hereinafter, the active energy ray-curable inkjet ink composition of the present invention (hereinafter, also simply referred to as the ink composition of the present invention) will be described in detail. The ink composition of the present invention is an active energy ray-curable inkjet ink composition containing a radical polymerizable monomer (A) and a photopolymerization initiator (B), wherein the radical polymerizable monomer (A) is (A) -1) at least a monofunctional monomer having a surface tension at 25 ° C of 32 mN / m or less, (A-2) a bifunctional monomer that is an alkanediol diacrylate, and (A-3) a monofunctional monomer having an aromatic ring. Here, the content of the monomer (A-1) in the ink composition is 5 to 40% by mass, and the mass of the monomer (A-1): the monomer (A-2) in the ink composition. The ratio is in the range of 2: 1 to 1: 4.

  In the present specification, the active energy ray-curable inkjet ink composition is an ink composition used for printing by an inkjet printer (also referred to as inkjet printing), and is cured by irradiation with active energy rays such as ultraviolet rays. Means an ink composition that can be used.

  The radical polymerizable monomer (A) used in the ink composition of the present invention may be a polymerizable unsaturated group (for example, a carbon-carbon double bond constituting an acryloyl group, a methacryloyl group, a vinyl group or an allyl group) upon irradiation with active energy rays. ) Is a monomer that causes a polymerization reaction, specifically, a monofunctional monomer having one functional group exhibiting reactivity upon irradiation with active energy rays (a monofunctional monomer having one polymerizable unsaturated group) ), A bifunctional monomer having two functional groups (a bifunctional monomer having two polymerizable unsaturated groups), and a polyfunctional monomer having three or more functional groups (having three or more polymerizable unsaturated groups) Polyfunctional monomer) and the like. In the present invention, the monomer generally has a molecular weight of less than 2,000. In the ink composition of the present invention, the content of the radically polymerizable monomer (A) is preferably from 60 to 95% by mass.

In the ink composition of the present invention, the radical polymerizable monomer (A) contains at least the following monomers (A-1) to (A-3) from the viewpoint of achieving both wettability and re-dischargeability. In addition, each of these monomers (A-1) to (A-3) may be used alone or in combination of two or more.
(A-1) Monofunctional monomer whose surface tension at 25 ° C. is 32 mN / m or less (A-2) Bifunctional monomer which is alkanediol diacrylate (A-3) Monofunctional monomer having an aromatic ring

  The monofunctional monomer (A-1) has a good wettability since the surface tension at 25 ° C. is 32 mN / m or less. The surface tension of the monofunctional monomer (A-1) at 25 ° C. is preferably 31 mN / m or less. On the other hand, although the lower limit of the surface tension of the monofunctional monomer (A-1) is not particularly limited, the surface tension of the monofunctional monomer (A-1) at 25 ° C. is preferably 20 mN / m or more from the viewpoint of re-ejectability. , 25 mN / m or more. The surface tension of the monomer can be measured by a plate method.

Further, among the monofunctional monomers (A-1), an alicyclic monofunctional monomer and a propylene glycol monofunctional monomer are preferable from the viewpoint of the effect of improving the wettability. Here, the “alicyclic monofunctional monomer” refers to a monofunctional monomer having a cyclic hydrocarbon group excluding an aromatic ring (for example, a cycloalkyl group, a cycloalkenyl group, etc.), and the cyclic hydrocarbon group is a monocyclic monomer. Or a polycyclic ring, and may be substituted with a substituent such as a straight-chain or branched-chain hydrocarbon group (eg, an alkyl group or an alkenyl group) or an alkoxy group. The “propylene glycol monofunctional monomer” is a monofunctional monomer having one or a plurality of propylene glycol-derived structural parts — (CHCH ₃ CH ₂ O) — or — (CH ₂ CHCH ₃ O) — in a molecule. Point to.

  Specific examples of the monofunctional monomer (A-1) include isobornyl acrylate (30.6 mN / m), methoxydipropylene glycol acrylate (29.4 mN / m), lauryl acrylate (29.8 mN / m), Stearyl acrylate (26.0 mN / m), decyl acrylate (24.8 mN / m), isodecyl acrylate (28.5 mN / m), tridecyl acrylate (29.6 mN / m), isoamyl acrylate (25.7 mN / m) ), Octyl acrylate (24.8 mN / m), isooctyl acrylate (25.7 mN / m), cyclohexyl acrylate (30.5 mN / m), (2-methyl-2-ethyl-1,3-dioxolan-4-) Yl) methyl acrylate (31.6 mN / m), 2-ethylhexyl Diglycol acrylate (30.2 mN / m), t-butylcyclohexyl acrylate (28.5 mN / m) and the like are preferable. Among them, isocyclic monofunctional monomers and propylene glycol monofunctional monomers are classified. Bornyl acrylate, methoxydipropylene glycol acrylate, cyclohexyl acrylate, t-butylcyclohexyl acrylate and the like are particularly preferred.

  In the ink composition of the present invention, the content of the monofunctional monomer (A-1) is 5 to 40% by mass, and preferably 10 to 35% by mass. When the content of the monofunctional monomer (A-1) is 5% by mass or more, good wettability can be given to the ink. On the other hand, if the content of the monofunctional monomer (A-1) exceeds 40% by mass, re-discharge properties may not be obtained.

  The bifunctional monomer (A-2) is an alkanediol diacrylate. By blending this with the ink, good re-discharge properties can be imparted to the ink. Here, the "alkanediol diacrylate" refers to a bifunctional monomer in which two hydroxy groups of a dihydric alcohol form an ester with two carboxyl groups of acrylic acid.

In addition, the bifunctional monomer (A-2) preferably has 6 to 10 carbon atoms between _two acryloyloxy groups CH ₂ ＣＨCHCOO— from the viewpoint of improving re-discharge properties. The site existing between the two acryloyloxy groups corresponds to a divalent hydrocarbon group derived from a dihydric alcohol. Here, examples of the hydrocarbon group include straight-chain or branched-chain hydrocarbon groups.

  Specific examples of the bifunctional monomer (A-2) include 1,12-dodecanediol diacrylate, 1,10-decanediol diacrylate, 2-methyl-1,8-octanediol diacrylate, and 2-butyl- 2-ethyl-1,3-propanediol diacrylate, 1,9-nonanediol diacrylate, 1,8-octanediol diacrylate, 1,7-heptanediol diacrylate, 1,6-hexanediol diacrylate, , 4-butanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, neopentyl glycol diacrylate, and the like.

  In the ink composition of the present invention, the mass ratio of the monofunctional monomer (A-1) to the bifunctional monomer (A-2) is in the range of 2: 1 to 1: 4, and 1.5: 1 to 1.5: 1. The ratio is preferably 1: 2, most preferably 1.3: 1 to 1: 1.5. When the mass ratio of the monomer (A-1) to the monomer (A-2) in the ink composition of the invention is within the above-specified range, both wettability and re-discharge property can be achieved.

  Further, in the ink composition of the present invention, the total content of the monofunctional monomer (A-1) and the bifunctional monomer (A-2) is preferably from 30 to 30 from the viewpoint of improving the wettability and the re-discharge property. It is preferably 70% by mass.

  In the ink composition of the present invention, the content of the bifunctional monomer (A-2) is preferably from 10 to 35% by mass from the viewpoint of the effect of improving the re-ejectability.

  The monofunctional monomer (A-3) is a monomer having an aromatic ring, has high compatibility with a photopolymerization initiator and an additive, does not cause undesired separation of the photopolymerization initiator and the like from the ink, and has a long life. This can contribute to both wettability and re-discharge properties. Here, the “aromatic ring” refers to a ring structure contained in an aromatic compound, and is an aromatic ring derived from an aromatic hydrocarbon such as a condensed ring such as a benzene ring or a naphthalene ring, or an aromatic heterocyclic ring such as a pyridine ring. An aromatic ring derived from a system compound can be exemplified. Further, the aromatic ring may be substituted with a substituent such as a straight-chain or branched-chain hydrocarbon group (for example, an alkyl group or an alkenyl group) or an alkoxy group.

  Specific examples of the monofunctional monomer (A-3) include neopentyl glycol acrylate benzoate, phenoxyethyl acrylate, benzyl acrylate, and phenoxydiethylene glycol acrylate. Of these, phenoxyethyl acrylate and benzyl acrylate And phenoxydiethylene glycol acrylate.

  In the ink composition of the present invention, the content of the monofunctional monomer (A-3) is preferably from 10 to 25% by mass from the viewpoint of the effect of improving the solubility.

  In the ink composition of the present invention, the radical polymerizable monomer (A) preferably further contains an alicyclic bifunctional monomer (A-4). By blending the alicyclic bifunctional monomer (A-4), the hardness of the cured printing layer can be improved. Here, the “alicyclic bifunctional monomer” refers to a bifunctional monomer having a cyclic hydrocarbon group excluding an aromatic ring (eg, a cycloalkyl group, a cycloalkenyl group, etc.), and the cyclic hydrocarbon group is a monocyclic monomer. Or a polycyclic ring, and may be substituted with a substituent such as a straight-chain or branched-chain hydrocarbon group (eg, an alkyl group or an alkenyl group) or an alkoxy group.

  Specific examples of the alicyclic bifunctional monomer (A-4) include dimethylol-tricyclodecane diacrylate, dimethylol-cyclohexane diacrylate, and the like. In addition, the monomer (A-4) may be used alone or in a combination of two or more.

  In the ink composition of the present invention, the content of the alicyclic bifunctional monomer (A-4) is preferably 5 to 15% by mass from the viewpoint of increasing the hardness of the cured printing layer.

〔式（１）中、Ｒ^１は、水素原子又は炭素数が１〜８のアルキル基であり、Ｒ^２は、水素原子又はメチル基である〕で表される単官能モノマー（Ａ−５）を更に含むことが好ましい。上記式（１）の単官能モノマー（Ａ−５）を配合することによって、印刷層の密着性を向上させることができる。上記式（１）の単官能モノマー（Ａ−５）は、そのアミド結合部位に由来する水素結合によって、印刷層の密着性を向上させることができる。 In the ink composition of the present invention, the radical polymerizable monomer (A) has the following formula (1):

[In the formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ² is a hydrogen atom or a methyl group.] (A-5) It is preferable to further include By blending the monofunctional monomer (A-5) of the above formula (1), the adhesion of the print layer can be improved. The monofunctional monomer (A-5) of the above formula (1) can improve the adhesion of the print layer by a hydrogen bond derived from the amide bond site.

In the above formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In the above formula (1), R ² is a hydrogen atom or a methyl group, and is preferably hydrogen.

  Specific examples of the monofunctional monomer (A-5) of the above formula (1) include Nn-butoxymethylacrylamide, N-isobutoxymethylacrylamide, N-methoxymethylacrylamide, and N-methylolacrylamide. No. In addition, the monofunctional monomer (A-5) of the above formula (1) may be used alone or in combination of two or more.

  In the ink composition of the present invention, the content of the monofunctional monomer (A-5) of the above formula (1) is preferably 1 to 9% by mass from the viewpoint of the effect of improving the adhesion of the print layer. .

  In the ink composition of the present invention, the radical polymerizable monomer (A) may further include a monomer other than the above-mentioned monomers (A-1) to (A-5) (hereinafter, referred to as another monomer).

  Among the other monomers, the monofunctional monomer preferably has a molecular weight of 1000 or less, and specific examples thereof include 4-hydroxybutyl acrylate, acryloylmorpholine, N, N-dimethylacrylamide, dicyclopentanyl acrylate, and dicyclopentanyl acrylate. Cyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, N-vinylcaprolactam, EO (ethylene oxide) -modified 2-ethylhexyl acrylate, N-vinyl-2-pyrrolidone, tetrahydrofurfuryl acrylate, and cyclic trimethylolpropane formal acrylate, and ethoxy -Diethylene glycol acrylate and the like. Among them, 4-hydroxybutyl acrylate, ethoxy-diethylene glycol acrylate, and tetrahydrofurfuryl acrylate are preferable from the viewpoint of the viscosity of the ink. These monofunctional monomers may be used alone or in combination of two or more.

  Among the other monomers, the bifunctional monomer preferably has a molecular weight of 1,000 or less, and specific examples thereof include polytetramethylene glycol diacrylate, neopentyl glycol diacrylate hydroxypivalate, and PO (propylene oxide) -modified Examples include pentyl glycol diacrylate, tetraethylene glycol diacrylate, triethylene glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and the like. In addition, these bifunctional monomers may be used alone or in combination of two or more.

  Among the other monomers, the trifunctional or higher polyfunctional monomer preferably has a molecular weight of 2,000 or less, and specific examples thereof include trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane. Triacrylate, ethoxylated glycerin triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, EO-modified diglycerin tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, and EO-modified dipentaerythritol hexaacrylate. No. Among them, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate and dipentaerythritol hexaacrylate are preferred. These polyfunctional monomers may be used alone or in combination of two or more.

  The ink composition of the present invention preferably further contains a radical polymerizable urethane oligomer (C). By blending the urethane oligomer (C), the hardness of the cured printing layer can be improved. In the present specification, the “radical polymerizable urethane oligomer” refers to a polymerizable unsaturated group (for example, a carbon-carbon double bond constituting an acryloyl group, a methacryloyl group, a vinyl group or an allyl group) upon irradiation with active energy rays. Is a urethane oligomer [oligomer having a plurality of urethane bonds (-NHCOO-)], and preferably a urethane acrylate oligomer having an acryloyl group as a polymerizable unsaturated group. The number of the polymerizable unsaturated groups in the urethane oligomer (C) is preferably 1 to 6, and more preferably 2 to 6. Further, the urethane oligomer (C) preferably has a molecular weight of 2,000 to 20,000. The molecular weight is a weight average molecular weight in terms of polystyrene.

  In the ink composition of the present invention, the content of the urethane oligomer (C) is preferably 5 to 15% by mass from the viewpoint of the effect of increasing the hardness of the print layer. When the ink composition of the present invention contains a urethane oligomer (C), the total content of the radical polymerizable monomer (A) and the urethane oligomer (C) may be 60 to 95% by mass based on the total mass of the ink. preferable.

The following are specific examples of the urethane acrylate oligomer. These urethane acrylate oligomers may be used alone or in a combination of two or more.
Beam set 502H, beam set 505A-6, beam set 550B, beam set 575, beam set AQ-17 (manufactured by Arakawa Chemical Industries),
AH-600, UA-306H, UA-306T, UA-306I, UA-510H, UF-8001G (manufactured by Kyoeisha Chemical Co., Ltd.),
CN910, CN959, CN963, CN964, CN965NS, CN966NS, CN969NS, CN980NS, CN981NS, CN982, CN983NS, CN985, CN991NS, CN996NS, CN2920, CN2921, CN8881NS, CN9001N, CN9001N, CN9001N, 9004N CN9028, CN9030, CN9178NS, CN9290, CN9893NS, CN929, CN989NS, CN968NS, CN9006NS, CN9010NS, CN9025, CN9026, CN9039, CN9062, CN91110NS, CN9029, CN8885NS, CN9013NS, CN973C 978NS, CN992, CN9167, CN9782, CN9783, CN970, (manufactured by Sartomer Co., Ltd.) CN971, CN972, CN975NS, CN9165,
U-2PPA, U-6LPA, U-10HA, U-10PA, UA-1100H, U-15HA, UA-53H, UA-33H, U-200PA, UA-200PA, UA-160TM, UA-290TM, UA- 4200, UA-4400, UA-122P (manufactured by Shin-Nakamura Chemical Co., Ltd.),
New Frontier R-1235, R-1220, RST-201, RST-402, R-1301, R-1304, R-1214, R-1302XT, GX-8801A, R-1603, R-1150D (Daiichi Kogyo Pharmaceutical Co., Ltd.) Company),
EBECRYL204, EBECRYL205, EBECRYL210, EBECRYL215, EBECRYL220, EBECRYL230, EBECRYL244, EBECRYL245, EBECRYL264, EBECRYL265, EBECRYL270, EBECRYL280 / 15IB, EBECRYL284, EBECRYL285, EBECRYL294 / 25HD, EBECRYL1259, EBECRYL1290, KRM8200, EBECRYL4820, EBECRYL4858, EBECRYL5129, EBECRYL8210, EBECRYL8254, EBECRYL8301R, EBECRYL8307, EBECRYL8402, EBECRYL8405, EBECRYL8411, EBECR L8465, EBECRYL8800, EBECRYL8804, EBECRYL8807, EBECRYL9260, EBECRYL9270, EBECRYL7735, EBECRYL8296, EBECRYL8452, EBECRYL8904, EBECRYL8311, EBECRYL8701, EBECRYL8667 (manufactured by Daicel-Orunekusu Co., Ltd.),
UV-1700B, UV-6300B, UV-7550B, UV-7600B, UV-7605B, UV-7610B, UV-7630B, UV-7640B, UV-7650B, UV-6630B, UV-7000B, UV-7510B, UV- 7461TE,
UV-2000B, UV-2750B, UV-3000B, UV-3200B, UV-3300B, UV-3310B, UV-3700B, UV6640B (manufactured by Nippon Gohsei),
Art Resin UN-333, UN-350, UN-1255, UN-2600, UN-2700, UN-5590, UN-6060PTM, UN-6200, UN-6202, UN-6300, UN-6301, UN-7600, UN-7700, UN-9000 PEP, UN-9200A, UN-3320HA, UN-3320HC, UN-904, UN-906S (manufactured by Negami Industry Co., Ltd.)

The ink composition of the present invention may further include a radical polymerizable oligomer other than the radical polymerizable urethane oligomer (C), preferably an acrylate oligomer. Specific examples include an amino acrylate oligomer [acrylate oligomer having a plurality of amino groups (-NH ₂ )], an epoxy acrylate oligomer [acrylate oligomer having a plurality of epoxy groups], and a silicone acrylate oligomer [having a plurality of siloxane bonds (-SiO-). Acrylate oligomer], ester acrylate oligomer [acrylate oligomer having a plurality of ester bonds (-COO-)], butadiene acrylate oligomer [acrylate oligomer having a plurality of butadiene units], and the like.

  The ink composition of the present invention contains a photopolymerization initiator (B). The photopolymerization initiator has an action of initiating polymerization of the above-described monomer or oligomer by being irradiated with an active energy ray. Further, the content of the photopolymerization initiator is preferably 1 to 25% by mass, more preferably 3 to 20% by mass, more preferably 3 to 15% by mass based on the total mass of the ink. preferable. If the content of the photopolymerization initiator is less than 1% by mass, the printing layer may be poorly cured. If the content exceeds 25% by mass, precipitates are generated at a low temperature and ink ejection becomes unstable. There is. Further, in order to accelerate the initiation reaction of the photopolymerization initiator, it is possible to use an auxiliary agent such as a photosensitizer in combination.

  Examples of the photopolymerization initiator include a benzophenone-based compound, an acetophenone-based compound, a thioxanthone-based compound, and a phosphine oxide-based compound.From the viewpoint of curability, the wavelength of the active energy ray to be irradiated and the photopolymerization initiator It is preferable that the absorption wavelengths overlap as much as possible.

As a specific example of the photopolymerization initiator,
2,2-dimethoxy-1,2-diphenylethan-1-one,
1-hydroxy-cyclohexyl-phenyl-ketone,
2-hydroxy-2-methyl-1-phenylpropan-1-one,
Benzophenone,
1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one,
2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) -benzyl] -phenyl} -2-methyl-propan-1-one;
Phenylglyoxylic acid methyl ester,
2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one,
2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone,
2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one,
Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide,
Bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide,
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide,
1,2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyloxime)],
Ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime),
2,4-diethylthioxanthone,
2-isopropylthioxanthone,
2-chlorothioxanthone and the like. Among these, from the viewpoint of curability of the ink, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and 2,4-diethylthioxanthone are preferred, and 2,4,6-trimethylbenzoyl- Diphenyl-phosphine oxide is particularly preferred. These photopolymerization initiators may be used alone or in combination of two or more.

  The ink composition of the present invention may further contain a light stabilizer. The light stabilizer has an action of absorbing ultraviolet light and preventing deterioration due to ultraviolet light. Examples of the light stabilizer include cyanoacrylate-based compounds, benzophenone-based compounds, benzoate-based compounds, benzotriazole-based compounds, hydroxyphenyltriazine-based compounds, benzylidenecamphor-based compounds, and inorganic fine particles. Is preferred from the viewpoint of the curability of the ink. From the viewpoint of curability, it is preferable that the wavelength of the active energy ray to be irradiated does not overlap with the absorption wavelength of the light stabilizer as much as possible. The content of the light stabilizer is preferably from 0.1 to 15% by mass, more preferably from 0.2 to 5% by mass, based on the total mass of the ink. If the content of the light stabilizer is less than 0.1% by mass, a sufficient effect of absorbing ultraviolet light cannot be obtained, and if the content exceeds 15% by mass, the curability of the printed layer may be reduced.

As a specific example of the light stabilizer,
2,4-dihydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone,
2-hydroxy-4-methoxybenzophenone-5-sulfonic acid,
2-hydroxy-4-octoxybenzophenone,
2-hydroxy-4-dodecyloxybenzophenone-2-hydroxy-4-benzyloxybenzophenone,
Bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane,
2,2′-dihydroxy-4-methoxybenzophenone,
2,2′-dihydroxy-4,4′-dimethoxybenzophenone,
2,2 ′, 4,4′-tetrahydroxybenzophenone,
2-hydroxy-4-methoxy-2′-carboxybenzophenone,
2- (2′-hydroxy-5′-methylphenyl) benzotriazole 2- [2′-hydroxy-3 ′, 5′-bis (α, α- (dimethylbenzyl) phenyl] benzotriazole;
2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole,
2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole,
2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole,
2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) benzotriazole,
2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole,
2,2′-methylene-bis [4- (1,1,3,3-tetramethylbutyl) -6- (2N-benzotriazol-2-yl) phenol],
A condensate of methyl-3- [3-tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate and polyethylene glycol,
2- (2-hydroxyphenyl) benzotriazole,
2- (2'-hydroxy-5'-methylphenyl) benzotriazole,
2,6-di-tert-butylphenyl-3 ′, 5′-di-tert-butyl-4′-hydroxybenzoate,
Hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate and the like. These light stabilizers may be used alone or in combination of two or more.

  The ink composition of the present invention may further contain a polymerization inhibitor. The polymerization inhibitor has a function of reacting with an active radical generated in the ink to prevent a polymerization reaction from occurring. When a polymerization inhibitor is added to the active energy ray-curable ink, the storage stability can be further improved. The content of the polymerization inhibitor is preferably from 0.001 to 5% by mass, more preferably from 0.001 to 1% by mass, based on the total mass of the ink. If the content of the polymerization inhibitor is less than 0.001% by mass, the effect of improving the storage stability cannot be sufficiently obtained, and if it exceeds 5% by mass, the curability of the printing layer cannot be maintained and decreases.

  Examples of the polymerization inhibitor include a hydroquinone compound, a phenol compound, a phenothiazine compound, a nitroso compound, and an N-oxyl compound.

  Specific examples of the polymerization inhibitor include phenol, o-, m- or p-cresol, 2-t-butyl-4-methylphenol, 6-t-butyl-2,4-dimethylphenol, 2,6- Di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-tert-butyl-2 Phenol compounds such as 2,6-dimethylphenol, hydroquinone, hydroquinone monomethyl ether, methylhydroquinone, 2,5-di-t-butylhydroquinone, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, and trimethylhydroquinone 4- Methylbenzcatechin, t-butylhydroquinone, 3-methylbenzcatechin, 2-meth Hydroquinone-based compounds such as le-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, benzoquinone, t-butyl-p-benzoquinone, 2,5-diphenyl-p-benzoquinone, and phenothiazines such as phenothiazine Compounds, nitroso compounds such as N-nitroso-N-phenylhydroxylamine ammonium, N-nitroso-N-phenylhydroxylamine aluminum salt, 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N- N-oxyl compounds such as oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl And the like. Among these, hydroquinone monomethyl ether, phenothiazine, N-nitroso-N-phenylhydroxylamine ammonium, and N-nitroso-N-phenylhydroxylamine aluminum salt are preferred from the viewpoint of improving storage stability and maintaining curability. These polymerization inhibitors may be used alone or in combination of two or more.

  The ink composition of the present invention can contain a coloring agent such as a dye or a pigment, but preferably contains a pigment from the viewpoint of weather resistance. The content of the coloring agent is, for example, 0.1 to 10% by mass based on the total mass of the ink. In addition, the coloring agent may be used alone or in combination of two or more.

Specific examples of the coloring agent include:
C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 14, 15, 16, 17, 24, 32, 34, 35, 36, 37, 41, 42, 43, 49, 53, 55, 60, 61, 62, 63, 65, 73, 74, 75, 77, 81, 83, 87, 93, 94, 95, 97, 98, 99, 100, 101, 104, 105, 106, 108, 109, 110, 111, 113, 114, 116, 117, 119, 120, 123, 124, 126, 127, 128, 129, 130, 133, 138, 139, 150, 151, 152, 153, 154, 155, 165, 167, 168, 169, 170, 172, 173, 174, 175, 176, 179, 180, 181, 182, 183, 184, 185, 91,193,194,199,205,206,209,212,213,214,215,219,
C. I. Pigment Orange 1, 2, 3, 4, 5, 13, 15, 16, 17, 19, 20, 21, 24, 31, 34, 36, 38, 40, 43, 46, 48, 49, 51, 60, 61, 62, 64, 65, 66, 67, 68, 69, 71, 72, 73, 74, 81,
C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 21, 22, 23, 31, 32, 38, 41, 48, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49, 52, 52: 1, 52: 2, 53: 1, 54, 57: 1, 58, 60: 1, 63, 64: 1, 68, 81: 1, 83, 88, 89, 95, 101, 104, 105, 108, 112, 114, 119, 122, 123, 136, 144, 146, 147, 149, 150, 164, 166, 168, 169, 170, 171, 172, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 187, 188, 190, 193, 194, 200, 202, 206, 20 , 208, 209, 210, 211, 213, 214, 216, 220, 220, 221 224, 226, 237, 238, 239, 242, 245, 247, 248, 251, 253, 254, 255, 256, 257 , 258, 260, 262, 263, 264, 266, 268, 269, 270, 271, 272, 279,
C. I. Pigment Violet 1, 2, 3, 3: 1, 3: 3, 5: 1, 13, 15, 16, 17, 19, 23, 25, 27, 29, 31, 32, 36, 37, 38, 42, 50,
C. I. Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 5, 15: 6, 16, 17: 1, 24, 24: 1, 25, 26, 27, 28, 29, 36, 56, 60, 61, 62, 63, 75, 79, 80,
C. I. Pigment Green 1, 4, 7, 8, 10, 15, 17, 26, 36, 50,
C. I. Pigment Brown 5, 6, 23, 24, 25, 32, 41, 42,
C. I. Pigment Black 1, 6, 7, 9, 10, 11, 20, 31, 32, 34,
C. I. Pigment White 1, 2, 4, 5, 6, 7, 11, 12, 18, 19, 21, 22, 23, 26, 27, 28,
Examples include aluminum flake, glass flake, and hollow particles.

Among these, from the viewpoint of weather resistance and color reproducibility of the printing layer,
C. I. Pigment Black 7,
C. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4, C.I. I. Pigment Blue 28,
C. I. Pigment Red 101, C.I. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 254, C.I. I. Pigment Red 282,
C. I. Pigment Violet 19,
C. I. Pigment White 6,
C. I. Pigment Yellow 42, C.I. I. Pigment Yellow 120, C.I. I. Pigment Yellow 138, C.I. I. Pigment Yellow 139, C.I. I. Pigment Yellow 150, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 155, C.I. I. Pigment Yellow 213 is preferred.

  When a pigment is used as the colorant, from the viewpoint of ejection stability, the pigment particles dispersed in the ink have a volume average particle diameter of 0.05 to 0.4 μm and a volume maximum particle diameter of 0.2. It is preferably about 1 μm. If the volume average particle diameter is larger than 0.4 μm and the volume maximum particle diameter is larger than 1 μm, it tends to be difficult to discharge ink stably. The volume average particle diameter and the volume maximum particle diameter can be measured by a measuring instrument using a dynamic light scattering method.

  The ink composition of the present invention may further contain a pigment dispersant, if necessary, to disperse the pigment. The content of the pigment dispersant is, for example, 0.1 to 5% by mass based on the total mass of the ink. Further, the pigment dispersant may be used alone or in combination of two or more.

As specific examples of the pigment dispersant,
ANTI-TERRA-U, ANTI-TERRA-U100,
ANTI-TERRA-204, ANTI-TERRA-205,
DISPERBYK-101, DISPERBYK-102,
DISPERBYK-103, DISPERBYK-106,
DISPERBYK-108, DISPERBYK-109,
DISPERBYK-110, DISPERBYK-111,
DISPERBYK-112, DISPERBYK-116,
DISPERBYK-130, DISPERBYK-140,
DISPERBYK-142, DISPERBYK-145,
DISPERBYK-161, DISPERBYK-162,
DISPERBYK-163, DISPERBYK-164,
DISPERBYK-166, DISPERBYK-167,
DISPERBYK-168, DISPERBYK-170,
DISPERBYK-171, DISPERBYK-174,
DISPERBYK-180, DISPERBYK-182,
DISPERBYK-183, DISPERBYK-184,
DISPERBYK-185, DISPERBYK-2000,
DISPERBYK-2001, DISPERBYK-2008,
DISPERBYK-2009, DISPERBYK-2020,
DISPERBYK-2025, DISPERBYK-2050,
DISPERBYK-2070, DISPERBYK-2096,
DISPERBYK-2150, DISPERBYK-2155,
DISPERBYK-2163, DISPERBYK-2164,
BYK-P104, BYK-P104S, BYK-P105,
BYK-9076, BYK-9077, BYK-220S, BYKJET-9150, BYKJET-9151 (all manufactured by BYK Japan KK),
Solsperse 3000, Solsperse 5000,
Solsperse 9000, Solsperse 11200,
Solsperse 13240, Solsperse 13650,
Solsperse 13940, Solsperse 16000,
Solsperse 17000, Solsperse 18000,
Solsperse 20000, Solsperse 21000,
Solsperse24000SC, Solsperse24000GR,
Solsperse 26000, Solsperse 27000,
Solsperse 28000, Solsperse 32000,
Solsperse 32500, Solsperse 32550,
Solsperse 32600, Solsperse 33000,
Solsperse 34750, Solsperse 35100,
Solsperse 35200, Solsperse 36000,
Solsperse 36600, Solsperse 37500,
Solsperse 38500, Solsperse 39000,
Solsperse 41000, Solsperse 54000,
Solsperse 55000, Solsperse 56000,
Solsperse 71000, Solsperse 76500,
Solsperse X300 (all manufactured by Lubrizol),
Dispalon DA-7301, Disparon DA-325, Disparon DA-375, Disparon DA-234 (all manufactured by Kusumoto Chemicals),
Floren AF-1000, Floren DOPA-15B, Floren DOPA-15BHFS, Floren DOPA-17HF, Floren DOPA-22, Floren DOPA-33, Floren G-600, Floren G-700, Floren G-700AMP, Floren G-700DMEA, Floren G-820, Floren G-900, Floren GW-1500, Floren KDG-2400, Floren NC-500, Floren WK-13E (all manufactured by Kyoeisha Chemical Co., Ltd.),
TEGO Dispers 610, TEGO Dispers 610S,
TEGO Dispers 630, TEGO Dispers 650,
TEGO Dispers 652, TEGO Dispers 655,
TEGO Dispers 662C, TEGO Dispers 670,
TEGO Dispers 685, TEGO Dispers 700,
TEGO Dispers 710, TEGO Dispers 740W,
LIPOTIN A, LIPOTIN BL,
LIPOTIN DB, LIPOTIN SB (all manufactured by Evonik Degussa),
PB821, PB822, PN411, PA111 (all manufactured by Ajinomoto Fine Techno Co.),
Texahole 963, Texahole 964, Texahole 987, Texahole P60, Texahole P61, Texahole P63, Texahole 3250, Texahole SF71, Texahole UV20, Texahole UV21 (all manufactured by Cognis),
BorchiGenSN88 and BorchiGen0451 (both manufactured by Bocious Inc.) and the like.

  The ink composition of the present invention comprises, as other components, an antioxidant, a surface tension modifier, a plasticizer, a rust inhibitor, a solvent, a non-reactive polymer, a filler, an antifoaming agent, a charge control agent, and a stress relaxing agent. If necessary, additives such as a penetrant, a light guide, a glitter, a magnetic material, and a phosphor may be used.

  The ink composition of the present invention is obtained by mixing various components appropriately selected as necessary and, if necessary, using a filter having a pore size of about 1/10 or less of the nozzle diameter of the inkjet print head to be used. It can be prepared by filtering the mixture obtained.

  The viscosity of the ink composition of the present invention at 40 ° C. is preferably from 5 to 25 mPa · s, and more preferably from 5 to 20 mPa · s. If the ink viscosity at 40 ° C. is within the above specified range, good ejection stability can be obtained. The ink viscosity can be measured using a cone-plate viscometer.

  The ink composition of the present invention preferably has a surface tension at 25 ° C. of 20 to 35 mN / m, and more preferably 23 to 33 mN / m. If the ink surface tension at 25 ° C. is within the above specified range, good ejection stability can be obtained. In addition, the ink surface tension can be measured by a plate method.

  Printing using the ink composition of the present invention can be performed on the underlayer by ordinary printing means to form a printed layer. Here, the printing means is preferably a printing means using an ink jet printer. Examples of the inkjet printer include, for example, an inkjet printer that discharges ink by a charge control system or a piezo system. Preferred examples are given.

The printing layer formed by the ink composition of the present invention is cured by irradiation with active energy rays such as ultraviolet rays. As a light source of the active energy ray, a high-pressure mercury lamp, a metal halide lamp, an LED lamp, or the like can be used. Further, the wavelength of the active energy ray irradiated for curing the printing layer preferably overlaps with the absorption wavelength of the photopolymerization initiator. The dominant wavelength of the line is preferably from 360 to 425 nm. In addition, it is preferable that the integrated light quantity of an active energy ray is in the range of 100 to 2000 mJ / cm ² .

  The underlayer means a layer serving as an underlayer for performing printing, and may be a base material itself, or a coating film or a print layer that can be formed on the base material.

  The substrate is not particularly limited, but a substrate used in an industrial line is preferably exemplified. Examples of the shape of the base material include a plate shape and the like. Examples of the material of the base material include plastics such as epoxy resin, ABS resin, polycarbonate, polyvinyl chloride, polystyrene, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polypropylene (PP), iron, stainless steel, and aluminum. Metal, wood, flexible board, calcium silicate board, gypsum slag bar light board, calcium carbonate board, wood chip cement board, precast concrete board, lightweight foam concrete (ALC) board, gypsum board, tile, glass, etc. Can be

  The paint used to form the coating film as the underlayer and the ink used to form the print layer as the underlayer include an organic solvent-based paint and ink using an organic solvent as a main solvent, a water-based paint using water as a main solvent, and Various conventionally known paints and inks such as inks, active energy ray-curable paints and inks, and powder paints can be used. In the above paints and inks, resins, hardener components, colorants, ultraviolet absorbers, light stabilizers, rheology modifiers, leveling agents, surface tension regulators, antioxidants, plasticizers, rust inhibitors, solvents, filling Agents, pH adjusters, defoamers, charge control agents, active energy ray-curable monomers and oligomers, photopolymerization initiators, photosensitizers, polymerization inhibitors, stress relievers, penetrants, light guides, brighteners , A magnetic material, a phosphor, a wax, and the like may be used as necessary. The paints and inks can be prepared by mixing various components appropriately selected as necessary.

  The coating method of the paint used for forming the coating film as the underlayer can be any of various conventionally used coating means such as air spray, airless spray, roll coater, flow coater, and electrostatic coating. As a printing method of the ink used to form the printing layer serving as the underlayer, various printing means conventionally used such as screen printing, gravure printing, and ink jet printing can be used.

It is preferable that the coating film and the printing layer, which are the underlayer, are cured and dried by irradiation with an active energy ray such as room temperature, heating, or ultraviolet light. The drying and curing conditions for heating are preferably a temperature of 60 to 250 ° C. and a time of 30 seconds to 1 hour. When curing is performed by irradiation with an active energy ray, the integrated light amount is preferably in the range of 100 to 2000 mJ / cm ² .

When the ink composition of the present invention contains the monofunctional monomer (A-5) of the formula (1), the underlayer reacts with the monofunctional monomer (A-5) of the formula (1). It is preferable to include a functional group which can be used. Thereby, the portion derived from the monofunctional monomer (A-5) of the above formula (1) present in the cured printing layer (specifically, the CONHCH ₂ OR ¹ site of the formula (1)) and the base layer include The functional groups can be reacted with each other by heating, and the adhesion between the printing layer and the underlayer can be improved.
In the ink composition of the present invention, a small amount of water contained in the components to be blended is present and remains in the cured printing layer. Therefore, the portion derived from the monofunctional monomer (A-5) of the above formula (1) present in the cured printing layer (specifically, the CONHCH ₂ OR ¹ site of the formula (1)) is included in the underlayer. It is considered that the reaction with the functional group to be performed becomes possible, and the interlayer adhesion can be improved.
Here, the heating temperature of the printing layer is preferably in the range of 70 to 300 ° C, more preferably in the range of 90 to 250 ° C, and most preferably in the range of 150 to 190 ° C. preferable. In the present invention, the heating temperature of the printed matter refers to the surface temperature of the underlayer or the base material. As for the heating time, for example, about 20 minutes is sufficient if it is within the above-specified range.

More specifically, the functional group capable of reacting with the monofunctional monomer (A-5) of the above formula (1) refers to the monofunctional monomer (A) of the above formula (1) present in the cured printing layer. -5) can be expressed as a functional group capable of reacting with a moiety derived from (specifically, the CONHCH ₂ OR ¹ site of the formula (1)) by heating. Specific examples thereof include a hydroxyl group, An amino group, an amide group, an imide group, and an alkoxymethyl group are preferably exemplified. Among these, a hydroxyl group is most preferred. The underlayer may include one or more of these functional groups, or may include two or more of these functional groups.

  The underlayer preferably contains at least one resin selected from the group consisting of an epoxy resin, a polyester resin, an acrylic resin, an alkyd resin, and a fluororesin. If the material of the underlayer is an organic material such as a resin (preferably an epoxy resin, a polyester resin, an acrylic resin, an alkyd resin or a fluororesin), the monofunctional monomer (A-5) of the above formula (1) is used. An underlayer containing a functional group capable of reacting can be easily prepared.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<Ink preparation method>
Mixtures according to the formulation shown in Tables 1 to 4 were obtained, kneaded with a bead mill and homogenized to prepare an active energy ray-curable inkjet ink.

a) Urethane oligomer (manufactured by Daicel Ornex)
b) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (manufactured by Lambson)
c) Pigment dispersant (by Big Chemie Japan)

<Wettability>
14 pL droplets were ejected by an inkjet printer (head temperature 45 ° C.) using an active energy ray-curable inkjet ink, and a 10% solid image was printed on a PET film. Three dots were randomly selected from the printed image, and the diameter was measured. The average value was evaluated for wettability according to the following criteria. The results are shown in Tables 1 to 4.
◎: Average diameter of 90 μm or more ○: Average diameter of 70 μm or more and less than 90 μm Δ: Average diameter of 50 μm or more and less than 70 μm ×: Average diameter of less than 50 μm

<Redischarge property>
A nozzle check image is printed on copy paper by an inkjet printer (head temperature: 45 ° C.) using an active energy ray-curable inkjet ink, and then the printer is left for 30 minutes without maintenance or printing, and the same image is again printed. Printed. The print appearance was visually evaluated for re-discharge properties according to the following criteria. The results are shown in Tables 1 to 4.
：: All nozzles were ejected, and there was no displacement of the landing position.
：: All nozzles could be discharged, but the landing positions were partially shifted.
Δ: Less than 20% of the nozzles did not discharge.
X: 20% or more of the nozzles did not discharge.

<Pencil hardness>
An aluminum plate was coated with a Dai Nippon Paint PE primer to form an underlayer. Next, a solid image (thickness: about 8 μm) is printed on the underlayer by an inkjet printer using an active energy ray-curable inkjet ink, and then an active energy ray having a main wavelength of 380 to 390 nm is printed using an ultraviolet LED lamp. Was irradiated at 2000 mJ / cm ² to cure the image (printed layer). The printed matter was evaluated for pencil hardness by scratch hardness (pencil method) according to JIS K-5600-5-4. The results are shown in Tables 1 to 4.

<Adhesiveness>
An underlayer and a printed material were prepared in the same manner as described in the above <Pencil hardness>. The printed layer of the printed material was subjected to a cross cut of 100 squares of 1 mm width, and a cellophane tape was sufficiently adhered and then peeled off. The adhesion was evaluated according to the following criteria. The results are shown in Tables 1 to 4.
：: No peeling was observed at the cut portion.
B: Peeling of less than 10% can be confirmed at the cut portion.
Δ: Peeling of 10% or more and less than 25% can be confirmed in the cut portion.
X: 25% or more peeling can be confirmed in the cut portion.

Claims (8)

An active energy ray-curable inkjet ink composition comprising a radical polymerizable monomer (A) and a photopolymerization initiator (B),
The radical polymerizable monomer (A) is a monomer (A-1) to (A-3) shown below:
(A-1) a monofunctional monomer having a surface tension at 25 ° C of 32 mN / m or less,
(A-2) A bifunctional monomer that is an alkanediol diacrylate (where the site existing between the two acryloyloxy groups of the alkanediol diacrylate corresponds to a divalent hydrocarbon group derived from a dihydric alcohol) And (A-3) at least a monofunctional monomer having an aromatic ring, wherein
The content of the monomer (A-1) in the ink composition is 15 to 40% by mass, and the mass ratio of the monomer (A-1) to the monomer (A-2) in the ink composition is 1. 3 : An active energy ray-curable ink-jet ink composition, which is in the range of 1-1 to 1.5 . The content of the monomer (A-1) in the ink composition is 15 to 35% by mass,
The content of the monomer (A-2) in the ink composition is 10 to 35% by mass,
The active energy ray-curable inkjet ink composition according to claim 1, wherein the content of the monomer (A-3) in the ink composition is 10 to 25% by mass. The active energy ray-curable inkjet according to claim 1 or 2 , wherein the total content of the monomer (A-1) and the monomer (A-2) in the ink composition is 30 to 70% by mass. Ink composition. The monomer (A-1) is at least one selected from the group consisting of alicyclic monofunctional monomers and propylene glycol monofunctional monomers, according to any one of claims 1 to 3 , wherein The active energy ray-curable inkjet ink composition according to the above. The active energy ray-curable inkjet according to any one of claims 1 to 4 , wherein the monomer (A-2) has 6 to 10 carbon atoms between two acryloyloxy groups. Ink composition. The ink composition further comprises a radically polymerizable urethane oligomer (C), and the content of the radically polymerizable urethane oligomer (C) in the ink composition is 5 to 15% by mass. The active energy ray-curable ink-jet ink composition according to any one of claims 1 to 5 . The radical polymerizable monomer (A) further includes an alicyclic bifunctional monomer (A-4), and the content of the monomer (A-4) in the ink composition is 5 to 15% by mass. The active energy ray-curable inkjet ink composition according to any one of claims 1 to 6 . The radical polymerizable monomer (A) is represented by the following formula (1):

[In the formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ² is a hydrogen atom or a methyl group.] The active energy ray-curable type according to any one of claims 1 to 7 , wherein the content of the monofunctional monomer (A-5) in the ink composition is 1 to 9% by mass. Ink jet ink composition.