JP6652622B2 - Energy ray-curable inkjet ink composition - Google Patents

Description

  The present invention relates to an energy ray-curable inkjet ink composition. More specifically, the present invention relates to an energy ray-curable inkjet ink composition that has high adhesion to the surface of a recording medium of various materials and realizes unprecedented excellent stretchability after curing. The energy ray-curable inkjet ink composition of the present invention can be used as both an image forming ink and a primer ink.

  The ink jet method of ejecting ink from the ink nozzle head as droplets has been applied to many printers because it is small and inexpensive and can form an image without contacting the surface of a recording medium. In recent years, commercial printing and industrial printing using an inkjet printer have been performed for advertisement, poster, decoration, etc., and accordingly, including impermeable recording medium surfaces such as plastics. There is a strong demand for enabling printing on various types of recording media and realizing a printing surface with higher image quality.

  In order to respond to such demands, researches have been made on an ink-jet ink composition that can improve the composition of an ink-jet ink composition used in an ink-jet printer and can print on the surface of various materials including a non-permeable recording medium. For example, an energy ray-curable inkjet ink composition having a specific viscosity containing a reactive liquid material containing monofunctional and polyfunctional monomers and oligomers, and oligomers and heterocyclic radiation-curable monomers as polymerizable compounds And / or energy ray-curable inkjet ink compositions containing alkoxylated monomers have been proposed (Patent Documents 1 and 2).

JP 2001-525479A JP 2004-514014 A

  However, the conventional energy ray-curable inkjet ink composition as described above imparts quick-drying to the ink composition for the purpose of preventing bleeding of the formed image and improving the quality of the formed image. In order to improve the adhesion of the ink composition to the surface of the recording medium, and to increase the adhesion of the ink composition, a polymerizable compound having relatively high curability is used. For this reason, when the printing surface formed using these ink compositions is stretched together with the recording medium after printing, the printed image is cracked or peeled off, resulting in poor stretchability. Therefore, it has been difficult to apply the method to a use in which a printed image is stretched together with a recording medium after printing, such as a marking film or a three-dimensional display member.

  An object of the present invention is to have excellent adhesion to recording media of various materials including a non-permeable recording medium surface, and furthermore, excellent flexibility and unprecedented printed images after printing. An object of the present invention is to provide an energy-ray-curable inkjet ink composition that achieves stretchability.

The present invention provides the following [1] to [8].
[1] An energy ray-curable ink-jet ink composition containing a polymerizable monomer, wherein the polymerizable monomer is a monofunctional monomer having an aromatic hydrocarbon-based cyclic structure in the molecule and an aliphatic carbonic acid in the molecule. A monofunctional monomer having a hydrogen-based cyclic structure, and 90% by mass or more of the polymerizable monomer is a monofunctional monomer;
Furthermore, an energy ray-curable inkjet ink composition containing a monofunctional monomer having the aromatic hydrocarbon-based cyclic structure and a monofunctional monomer other than the monofunctional monomer having the aliphatic hydrocarbon-based cyclic structure.
[2] The energy ray-curable inkjet ink composition according to [1], wherein the monofunctional monomer having an aromatic hydrocarbon-based cyclic structure includes 2-hydroxy-3-phenoxypropyl acrylate.
[3] The monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure is isobornyl acrylate, cyclohexyl acrylate, 3,5,5-trimethylcyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl The energy ray-curable inkjet ink composition according to the above [1] or [2], comprising at least one selected from the group consisting of acrylates and dicyclopentanyl acrylates.
[4] The above-mentioned [1] to [1], wherein the monofunctional monomer having an aromatic hydrocarbon-based cyclic structure and the monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure are contained in a mass ratio of 1:10 to 10: 1. 3] The energy ray-curable inkjet ink composition according to any one of [1] to [3].
[5] The energy ray-curable inkjet ink composition according to any one of [1] to [4] above, which contains 2-hydroxy-3-phenoxypropyl acrylate and isobornyl acrylate as a polymerizable monomer.
[6] Any of the above-mentioned [1] to [5], containing at least one photopolymerization initiator selected from the group consisting of a thioxanthone-based initiator, an acylphosphine oxide-based initiator and an α-aminoalkylphenone-based initiator. An energy ray-curable inkjet ink composition according to any one of the above.
[7] The energy ray-curable inkjet ink composition according to any one of [1] to [6], which is used as an image forming ink.
[8] The energy ray-curable inkjet ink composition according to any one of [1] to [6], which is used as a primer ink.

  According to the present invention, an energy ray-curable inkjet ink composition having high adhesion to the surface of a recording medium made of various materials, and achieving unprecedented flexibility and stretchability after curing Can be provided.

  Hereinafter, the present invention will be described in detail.

(Polymerizable compound)
The energy ray-curable inkjet ink composition of the present invention (hereinafter sometimes referred to as “the ink composition of the present invention”) is a monofunctional polymerizable compound having an aromatic hydrocarbon-based cyclic structure in the molecule. It contains a monomer and a monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure in the molecule.

  In the present invention, a monofunctional monomer having an aromatic hydrocarbon-based cyclic structure in the molecule (hereinafter, sometimes referred to as “aromatic cyclic structure monofunctional monomer”) refers to one unsaturated bond in the molecule. And a polymerizable monomer having at least one aromatic hydrocarbon cyclic structure. Examples of the cyclic structure of the aromatic hydrocarbon include an aromatic hydrocarbon ring structure such as a monocyclic aromatic such as benzene and a polycyclic aromatic such as naphthalene and anthracene. As the unsaturated bond, an ethylenic double bond is preferable. The ethylenic double bond preferably has a (meth) acryloyloxy group, a (meth) acrylamide group, a vinyl group or a vinyl ether group in the molecule, and particularly preferably a (meth) acryloyloxy group.

Examples of such an aromatic cyclic structure monofunctional monomer include benzyl (meth) acrylate, 4-butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate (2-HPA), 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropylphthalic acid, EO-modified phenol (meth) acrylate, EO-modified cresol (meth) acrylate, EO-modified nonylphenol (meth) acrylate, PO-modified nonylphenol (meth) a Having one or more aromatic hydrocarbon cyclic structure in the molecule, such as relations (meth) acrylate compounds. Also, for example, styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, vinyl benzoate methyl ester, 3-methyl Styrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene, 3-octyl Styrene, 4-octylstyrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allylstyrene, isopropenylstyrene, butenylstyrene, octenylstyrene, 4-t- Aromatic vinyl compounds such as ethoxycarbonylstyrene, 4-methoxystyrene and 4-t-butoxystyrene; and one or more aromatic hydrocarbon compounds in the molecule such as benzyl vinyl ether, phenylethyl vinyl ether and phenoxy polyethylene glycol vinyl ether. A vinyl ether compound having a cyclic structure can also be used. These can be used alone or in combination of two or more. In particular, the ink composition of the present invention preferably contains, as an aromatic cyclic structure monofunctional monomer, a (meth) acrylate compound having one or more aromatic hydrocarbon-based cyclic structures in the molecule, More preferably, it contains -3-phenoxypropyl acrylate. By containing 2-hydroxy-3-phenoxypropyl acrylate, it is possible to obtain an ink composition having sufficient stretchability while ensuring excellent adhesion to recording media of various materials.
In this specification, “(meth) acrylate” refers to acrylate or methacrylate, and the notations such as “(meth) acryloyloxy” and “(meth) acrylamide” have the same meaning.

  In the present invention, a monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure in the molecule (hereinafter, sometimes referred to as an “alicyclic monofunctional monomer”) refers to one unsaturated bond in the molecule. And a polymerizable monomer having one or more alicyclic hydrocarbon structures. Examples of the alicyclic hydrocarbon structure include aliphatic cyclic structures such as a cycloalkane skeleton, an admantan skeleton, and a norbornane skeleton. As the unsaturated bond, an ethylenic double bond is preferable. The ethylenic double bond preferably has a (meth) acryloyloxy group, a (meth) acrylamide group, a vinyl group or a vinyl ether group in the molecule, and particularly preferably a (meth) acryloyloxy group.

  Examples of such alicyclic monofunctional monomers include cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, and isobornyl (meth) acrylate. And (meth) acrylate compounds having an alicyclic hydrocarbon structure in the molecule, such as acrylate, 3,5,5-trimethylcyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, and dicyclopentanyl acrylate. Can be Further, a vinyl ether compound having an alicyclic hydrocarbon structure in a molecule such as cyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, 4-methylcyclohexylmethyl vinyl ether, and 4-hydroxymethylcyclohexylmethyl vinyl ether can also be used. These can be used alone or in combination of two or more. In particular, the ink composition of the present invention preferably contains, as an alicyclic structure monofunctional monomer, a (meth) acrylate compound having an alicyclic hydrocarbon structure in the molecule, and is preferably isobornyl acrylate, cyclohexyl acrylate, or 5, at least one selected from the group consisting of 5,5-trimethylcyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate and dicyclopentanyl acrylate. More preferred. By containing at least one selected from the above group as the polymerizable monomer, an ink composition having sufficient stretchability while ensuring excellent adhesion to recording media of various materials is obtained. be able to.

  In a preferred embodiment of the present invention, the ink composition of the present invention contains 2-hydroxy-3-phenoxypropyl acrylate and isobornyl acrylate as polymerizable monomers.

  The ink composition of the present invention comprises an aromatic cyclic monofunctional monomer and an alicyclic monofunctional monomer in an aromatic cyclic monofunctional monomer: alicyclic monofunctional monomer ratio of 1:10 to 10: 1. It is preferably contained in a mass ratio, more preferably in a mass ratio of 1: 5 to 5: 1, and particularly preferably in a mass ratio of 1: 4 to 3: 2. By containing these two types of monofunctional monomers in the above range, it is possible to impart sufficient stretchability and adhesion to the obtained ink composition.

  The ink composition of the present invention, in addition to a monofunctional monomer having an aromatic hydrocarbon-based cyclic structure in the molecule and a monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure in the molecule, as a polymerizable compound, It may contain a monofunctional monomer having a structure different from the above two types of monofunctional monomers. Such a monofunctional monomer is not particularly limited as long as it is a compound that can be polymerized by an active radical or the like generated from a photopolymerization initiator by the action of light, and a monofunctional monomer conventionally known in this field can be used. Can be used.

  The monofunctional monomer that the ink composition of the present invention may contain in addition to the two monofunctional monomers is, for example, a polymerizable monomer having one ethylenic double bond in a molecule having a property of being cured by energy rays. For example, monofunctional (meth) acrylate compounds, (meth) acrylamide compounds and monofunctional vinyl ether compounds.

  Specific examples of the monofunctional (meth) acrylate compound include, for example, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, Decyl (meth) acrylate, isodecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, 2-ethylhexyldiglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, cyanoethyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl (meth) a Relate, alkoxyethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, 2- (2-butoxyethoxy) ethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate 1H, 1H, 2H, 2H-perfluorodecyl (meth) acrylate, glycidyl (meth) acrylate, glycidyloxybutyl (meth) acrylate, glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, Tetrahydrofurfuryl (meth) acrylate, hydroxyalkyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Tyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, trimethoxysilylpropyl ( (Meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, oligoethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide (meth) acrylate, oligoethylene oxide (meth) acrylate, oligoethylene oxide monoalkyl ether (meth) ) Acrylate, polyethylene oxide monoalkyl ether (meth) acrylate , Dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl ether (meth) acrylate, oligopropylene oxide monoalkyl ether (meth) acrylate, 2-methacryloyloxyethyl succinic acid, butoxydiethylene glycol (meth) acrylate, trifluoroethyl ( (Meth) acrylate, perfluorooctylethyl (meth) acrylate, and EO-modified-2-ethylhexyl (meth) acrylate.

  As the (meth) acrylamide compound, specifically, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-n-butyl (meth) ) Acrylamide, Nt-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide and (meth) acryloylmorpholine are exemplified.

  Specific examples of the monofunctional vinyl ether compound include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, methoxyethyl vinyl ether, and ethoxyethyl. Vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, polyethylene Recall vinyl ether, chloroethyl vinyl ether, etc. chlorobutyl vinyl ether and chloroethoxyethyl vinyl ether.

  Above all, as a monofunctional monomer other than the aromatic cyclic monofunctional monomer and the alicyclic monofunctional monomer that the ink composition of the present invention can contain, a monofunctional (meth) acrylate compound is preferable, and isooctyl acrylate, -Ethylhexyl acrylate and tetrahydrofurfuryl acrylate are particularly preferred. These monofunctional monomers are suitable for preparing a low-viscosity ink composition.

  When the ink composition of the present invention contains a monofunctional monomer other than the aromatic cyclic structure monofunctional monomer and the alicyclic structure monofunctional monomer, the content is determined by the aromatic cyclic structure monofunctional monomer and the alicyclic structure It is preferably at most 20 parts by mass, more preferably at most 10 parts by mass, based on 100 parts by mass of the monofunctional monomer in total. Although the lower limit is not particularly limited, the adhesion to the recording medium surface may be reduced if the content of the monofunctional monomer other than the aromatic cyclic structure monofunctional monomer and the alicyclic structure monofunctional monomer is large, The smaller the content of the monofunctional monomer other than the aromatic cyclic structure monofunctional monomer and the alicyclic structure monofunctional monomer, the better. Therefore, the monofunctional monomer constituting the ink composition of the present invention may be only an aromatic cyclic monofunctional monomer and an alicyclic monofunctional monomer.

  Further, the ink composition of the present invention may contain a polyfunctional monomer and / or a polymerizable oligomer as a polymerizable compound. The polyfunctional monomer and the polymerizable oligomer are not particularly limited as long as they are compounds that can be polymerized by an active radical or the like generated from a photopolymerization initiator by the action of light, and conventionally known compounds can be used. . In this specification, the term “oligomer” refers to those having a weight average molecular weight of 800 or more and 10,000 or less, and the term “weight average molecular weight” means the weight average molecular weight in terms of polystyrene measured by GPC (Gel Permeation Chromatography). I do. In general, by containing a polyfunctional monomer, the strength of a coating film on the surface of a printed material obtained by using the ink composition can be improved. Further, by containing a polymerizable oligomer, excellent flexibility and stretchability can be imparted to the ink composition.

  The polyfunctional monomer that can be contained in the ink composition of the present invention is a polymerizable monomer having two or more unsaturated bonds in a molecule having a property of being polymerized by energy rays. For example, bifunctional, trifunctional, tetrafunctional, pentafunctional and hexafunctional polyfunctional (meth) acrylate compounds having an ethylenic double bond as an unsaturated bond, polyfunctional vinyl ether compounds and the like can be mentioned.

As the bifunctional (meth) acrylate compound, specifically, for example,
1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2,4-dimethyl-1,5-pentanediol di (meth) acrylate Butylethylpropanediol (meth) acrylate, ethoxylated cyclohexanemethanol di (meth) acrylate, polyethylene glycol di (meth) acrylate, oligoethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, 2-ethyl- 2-butyl-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate hydroxypivalate, EO-modified bisphenol A di (meth) acrylate, bisphenol F polyethoxydi (meth) Acrylate, polypropylene glycol di (meth) acrylate, oligopropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 2-ethyl-2-butylpropanediol di (meth) acrylate, 1,9- Nonanedi (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate and tricyclodecanedi (meth) acrylate.

As the trifunctional (meth) acrylate compound, for example,
Trimethylolpropane tri (meth) acrylate, trimethylolethanetri (meth) acrylate, alkylene oxide-modified tri (meth) acrylate of trimethylolpropane, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, trimethylol Propane tris ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide-modified tri (meth) acrylate, dipentaerythritol propionate tri (meth) acrylate, tris ((meth) acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde Modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) acrylate, propoxylated trimethylol pro Entry (meth) acrylate, and ethoxylated glycerin triacrylate, and the like.

  Examples of the tetrafunctional (meth) acrylate include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate, dipentaerythritol tetrapropionate tetra (meth) acrylate, and ethoxylated pentaerythritol Tetra (meth) acrylate and the like, pentafunctional (meth) acrylate as sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate, and hexafunctional (meth) acrylate as dipentaerythritol hexa (meth) acrylate Acrylate, sorbitol hexa (meth) acrylate, alkylene oxide-modified hexa (meth) acrylate of phosphazene and caprolactone-modified dipentane Risuri Tall hexa (meth) acrylate, and the like.

Examples of polyfunctional vinyl ether compounds include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, and the like. Divinyl ethers;
Trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide Addition trimethylolpropane trivinyl ether, ethylene oxide addition ditrimethylolpropane tetravinyl ether, propylene oxide addition ditrimethylolpropane tetravinyl ether, ethylene oxide addition pentaerythritol tetravinyl ether, propylene oxide addition pentaerythritol La ether, ethylene oxide adduct of dipentaerythritol hexavinyl ether, polyfunctional vinyl compounds such as propylene oxide adduct of dipentaerythritol hexa vinyl ether.

Examples of the polymerizable oligomer that can be contained in the ink composition of the present invention include a urethane acrylate oligomer, a polyester acrylate oligomer, and an epoxy acrylate oligomer.
Examples of the urethane acrylate oligomer include a reaction product of an isocyanate compound obtained by reacting a polyol with a polyvalent isocyanate, and a (meth) acrylate having a hydroxy group. Examples of the isocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, and hydrogenated xylylene diisocyanate. Examples of the (meth) acrylate having a hydroxy group include 2-hydroxyethyl acrylate.
The polymerizable oligomer is preferably a urethane acrylate oligomer, a polyester acrylate oligomer, an epoxy acrylate oligomer or a mixture thereof, and more preferably a urethane acrylate oligomer. As the urethane acrylate oligomer, an aliphatic urethane acrylate oligomer composed of an aliphatic isocyanate and an acrylate having a hydroxy group is preferable from the viewpoint of easily providing adhesion and easily obtaining flexibility.

  In the present invention, the proportion of the monofunctional monomer in the total amount of the polymerizable monomers contained in the ink composition of the present invention is 90% by mass or more, preferably 95% by mass or more. Further, all the polymerizable monomers contained therein may be monofunctional monomers. In other words, when the ink composition of the present invention contains a polyfunctional monomer, its content is less than 10% by mass, preferably less than 5% by mass, based on the total amount of the polymerizable monomer. If the ratio of the monofunctional monomer to the total amount of the polymerizable monomer is less than 90% by mass, the obtained ink composition cannot be provided with sufficient flexibility, resulting in an ink composition having poor stretchability. Adhesion to the surface of the recording medium made of the material also decreases. Here, the amount of the monofunctional monomer means the total amount of the monofunctional monomer having an aromatic cyclic structure, the monofunctional monomer having an alicyclic structure, and the monofunctional monomer having a structure other than the above two types.

  The content of the polymerizable monomer contained in the ink composition of the present invention is preferably at least 70 parts by mass, more preferably at least 80 parts by mass, based on 100 parts by mass of the ink composition. Also, it is preferably at most 95 parts by mass, more preferably at most 90 parts by mass. When the ink composition of the present invention contains a polymerizable oligomer, the content is preferably 20 parts by mass or less, more preferably 10 parts by mass or less based on 100 parts by mass of the ink composition. By containing a polymerizable oligomer in addition to the polymerizable monomer, excellent flexibility and stretchability can be imparted to the ink composition.

(Coloring material)
The ink composition of the present invention contains a coloring material. As the colorant used in the present invention, conventionally known various dyes can be used, but from the viewpoint of weather resistance, it is preferable to use one or both of an inorganic pigment and an organic pigment.
Basically, a pigment having a cyan color, a pigment having a magenta color, a pigment having a yellow color, a black pigment, a white pigment, and the like are used. In some cases, an image having excellent color reproducibility can be formed by using a special color pigment such as violet, blue, green, orange, and red. In addition to general black pigments and white pigments, and pigments of three primary colors of cyan, magenta and yellow, for example, metal luster pigments such as gold and silver, and colorless or light-colored extender pigments are contained according to purposes. May be.

  As the inorganic pigment, specifically, for example, titanium oxide, zinc white, zinc oxide, tripon, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium Red, Bengal, Molybdenum Red, Chrome Vermillion, Molybdate Orange, Graphite, Chrome Yellow, Cadmium Yellow, Yellow Iron Oxide, Titanium Yellow, Chromium Oxide, Pyridian, Cobalt Green, Titanium Cobalt Green, Cobalt Chrome Green, Ultramarine, Ultra Marine blue, navy blue, cobalt blue, cerulean blue, manganese violet, cobalt violet, mica and the like.

  As the organic pigment, specifically, for example, azo-based, azomethine-based, polyazo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, indigo-based, thioindigo-based, quinophthalone-based, benzimidazolone-based, and isoindoline-based organic pigments And the like. Further, carbon black composed of acidic, neutral or basic carbon may be used. Further, hollow particles of cross-linked acrylic resin may be used as the organic pigment.

  Specific examples of the pigment having a cyan color include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Pigment Blue 60 and the like. Among them, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4 is preferred.

  Specific examples of the pigment having a magenta color include C.I. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 112, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 168, C.I. I. Pigment Red 184, C.I. I. Pigment Red 202, C.I. I. Pigment Red 209, C.I. I. Pigment Red 254, C.I. I. Pigment Violet 19 and the like. Among them, C.I. I. Pigment Red 122, C.I. I. Pigment Red 202, C.I. I. Pigment Red 209, C.I. I. Pigment Red 254, and C.I. I. Pigment Violet 19 is preferable.

  Specific examples of the pigment having a yellow color include C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14C, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 17, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment Yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 95, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 98, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 120, C.I. I. Pigment Yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment Yellow 130, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 139, C.I. I. Pigment yellow 147, C.I. I. Pigment Yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment Yellow 185, C.I. I. Pigment Yellow 213, C.I. I. Pigment Yellow 214 and the like. Among them, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 120, C.I. I. Pigment Yellow 128, 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 154, C.I. I. Pigment yellow 155, C.I. I. Pigment Yellow 213, and C.I. I. Pigment Yellow 214 is preferable.

  Specific examples of the black pigment include HCF, MCF, RCF, LFF, and SCF manufactured by Mitsubishi Chemical Corporation; Monarch and Regal manufactured by Cabot Corporation; color black, special black, and print tex manufactured by Degussa Huls; Toka Black manufactured by Tokai Carbon; Raven manufactured by Columbia; Among these, HCF # 2650, HCF # 2600, HCF # 2350, HCF # 2300, MCF # 1000, MCF # 980, MCF # 970, MCF # 960, MCF88, LFFMA7, MA8, MA11, MA77 manufactured by Mitsubishi Chemical Corporation. , MA100, and at least one selected from the group consisting of PRINTEX 95, PRINTEX 85, PRINTEX 75, PRINTEX 55, and PRINTEX 45 manufactured by Degussa Huls.

Pigment Whites 6, 18, and 21 can be exemplified as white pigments. Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), and titanium oxide (TiO ₂ , so-called titanium white). ), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) and the like can be used. Titanium oxide has a lower specific gravity than other white pigments, has a large refractive index, and is chemically and physically stable, so it has a large hiding power and coloring power as a pigment, and furthermore has a high acidity, alkalinity and other environmental properties. Also has excellent durability against Therefore, it is preferable to use titanium oxide as the white pigment. If necessary, other white pigments (may be other than the white pigments listed) may be used.

  The content of the coloring material in the ink composition may be appropriately selected depending on the color and the purpose of use, but is generally preferably 0.1 part by mass or more based on 100 parts by mass of the ink composition. It is more preferably at least 0.3 part by mass, more preferably at most 20 parts by mass, and even more preferably at most 15 parts by mass. When the content of the coloring material is in the above range, the ink composition of the present invention having excellent image coloring power while maintaining fluidity without increasing the viscosity of the ink composition can be obtained.

When a pigment is used as the coloring material, a pigment derivative or a pigment dispersant may be further used to improve the dispersibility of the pigment. Specific examples of the pigment derivative include a pigment derivative having a dialkylaminoalkyl group and a pigment derivative having a dialkylaminoalkylsulfonic acid amide group. Specific examples of the pigment dispersant include an ionic or nonionic surfactant, and an anionic, cationic or nonionic polymer compound. Among these, a polymer compound containing a cationic group or an anionic group is preferable from the viewpoint of dispersion stability. Examples of commercially available pigment dispersants include SOLPERSE manufactured by Lubrizol, DISPERBYK manufactured by BYK Chemie, and EFKA manufactured by EFKA Additives.
The content of each of the pigment derivative and the pigment dispersant in the ink composition is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the ink composition.

(Photopolymerization initiator)
The ink composition of the present invention preferably contains a photopolymerization initiator in order to initiate polymerization by low-energy irradiation means. Examples of the photopolymerization initiator that can be contained in the ink composition of the present invention include an acylphosphine oxide-based initiator, an α-aminoalkylphenone-based initiator and a thioxanthone-based initiator, an arylalkylketone-based initiator, and an oxime-ketone-based initiator. And acylphosphonate-based initiators, S-phenyl thiobenzoate-based initiators, titanocene-based initiators, aromatic ketone-based initiators, benzyl-based initiators, quinone derivative-based initiators, and ketocoumarin-based initiators. Among them, it is preferable to contain at least one photopolymerization initiator selected from the group consisting of an acylphosphine oxide initiator, an α-aminoalkylphenone initiator and a thioxanthone initiator. By using such a photopolymerization initiator, sufficient curability can be imparted. In particular, it is preferable to use an α-aminoalkylphenone-based initiator and a thioxanthone-based initiator in combination, because they are less susceptible to oxygen inhibition and a more sufficient curing rate can be obtained.

  Specific examples of the acylphosphine oxide initiator include, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 3,5,6-tetramethylbenzoyldiphenylphosphine oxide, 2,6-dimethylbenzoyldiphenylphosphine oxide, 4-methylbenzoyldiphenylphosphine oxide, 4-ethylbenzoyldiphenylphosphine oxide, 4-isopropylbenzoyldiphenylphosphine oxide, 1-methyl Cyclohexanoylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine Oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2,4,6-trimethylbenzoylphenylphosphinic acid isopropyl ester, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide And so on. These may be used alone or in combination of two or more. Examples of commercially available acylphosphine oxide-based initiators include, for example, DAROCURE TPO manufactured by BASF.

  As the α-aminoalkylphenone-based initiator, specifically, for example, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino- 1- (4-morpholinophenyl) butanone-1, 2-methyl-1- [4- (methoxythio) -phenyl] -2-morpholinopropan-2-one and the like. These may be used alone or in combination of two or more. Examples of commercially available α-aminoalkylphenone-based initiators include IRGACURE 369 and IRGACURE 907 manufactured by BASF.

  Specific examples of the thioxanthone initiator include, for example, thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone and the like. These may be used alone or in combination of two or more. Examples of commercially available thioxanthone-based initiators include KAYACURE DETX-S manufactured by Nippon Kayaku Co., Ltd., and Chivacure ITX manufactured by Double Bond Chemical Co., Ltd.

The content of the photopolymerization initiator in the ink composition depends on the content and type of the polymerizable compound, but is preferably 2 parts by mass or more, more preferably 5 parts by mass, based on 100 parts by mass of the ink composition. And more preferably 30 parts by mass or less, more preferably 20 parts by mass or less. When the content of the photopolymerization initiator is in the above range, sufficient curability can be imparted to the ink composition, and precipitation of the ink composition at a low temperature can be prevented.
Further, when an α-aminoalkylphenone-based initiator and a thioxanthone-based initiator are used in combination as a photopolymerization initiator, the ratio thereof is as follows based on the total amount of the α-aminoalkylphenone-based initiator and the thioxanthone-based initiator. Is preferably within the range.
α-aminoalkylphenone-based initiator: 40 to 99%
Thioxanthone initiator: 1 to 60%

  When the ink composition of the present invention contains a photopolymerization initiator other than an acylphosphine oxide-based initiator, an α-aminoalkylphenone-based initiator, and a thioxanthone-based initiator as a photopolymerization initiator, another photopolymerization initiator may be used. The content of the polymerization initiator is preferably 5 parts by mass or less based on 100 parts by mass of the ink composition. If the content of the other photopolymerization initiator is too large, the reactivity may decrease.

(Surface conditioner)
The ink composition of the present invention preferably contains a surface conditioner for the purpose of improving wettability on the surface of the recording medium and preventing repellency. As used herein, the term “surface conditioner” refers to a material that has a hydrophilic portion and a hydrophobic portion in its molecular structure and can adjust the surface tension of an ink composition when added.

  Specific examples of the surface conditioner that can be contained in the ink composition of the present invention include anionic surface conditioners such as dialkyl sulfosuccinates, alkylnaphthalene sulfonates, and fatty acid salts, polyoxyethylene alkyl ethers, and polyoxyethylene. Nonionic surface conditioners such as ethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, cationic surface conditioners such as alkylamine salts and quaternary ammonium salts, and silicone surface conditioners And a fluorine-based surface conditioner. These surface conditioners can be used alone or in combination of two or more.

  The content of the surface conditioner in the ink composition of the present invention can be appropriately selected depending on the purpose of use. For example, the total amount is preferably 0.01 parts by mass or more based on 100 parts by mass of the ink composition, It is more preferably at least 0.05 part by mass, preferably at most 5 parts by mass, more preferably at most 2.5 parts by mass. If the amount of the surface conditioner is too large, undissolved matter may be generated or foaming may be caused.

(Geling inhibitor)
The ink composition of the present invention preferably contains a gelling inhibitor. Storage stability can be improved by containing a gelling inhibitor. Also, from the viewpoint of preventing head clogging due to polymerization of the polymerizable compound by thermal energy, it is preferable to add a gelling inhibitor.

Examples of the gelling inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, hydroquinone monomethyl ether, hydroquinone monobutyl ether, TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), and TEMPOL (4-hydroxy -2,2,6,6-tetramethylpiperidineoxyl), cuperon Al and the like. Examples of commercially available products include IRGASTAB UV-10, IRGASTAB UV-22, FIRSTCURE ST-1 (manufactured by ALBEMARLE), and the like. These gelling inhibitors can be used alone or in combination of two or more.

  The content of the gelling inhibitor in the ink composition of the invention is preferably at least 0.001 part by mass, more preferably at least 0.01 part by mass, based on 100 parts by mass of the ink composition. Also, it is preferably at most 5 parts by mass, more preferably at most 1 part by mass.

The ink composition of the present invention may contain a sensitizing dye as a sensitizer. By including a sensitizer, the sensitivity of the photopolymerization initiator can be improved. Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in a range of 350 nm to 450 nm. For example, polynuclear aromatics, xanthenes, cyanines, merocyanines, thiazines, acridines, anthraquinones, coumarins and the like are preferable.
Further, as the co-sensitizer, a known compound having an effect of further improving sensitivity or suppressing polymerization inhibition by oxygen can be used. Examples include amines, and specific examples include triethanolamine, ethyl p-dimethylaminobenzoate, p-formyldimethylaniline, p-methylthiodimethylaniline and the like.

  The ink composition of the present invention uses a non-permeating or slow-permeating recording medium in terms of stability over time, such as non-uniformity over time, turbidity of a liquid caused by precipitation of a dye, and the like. Does not substantially contain water from the viewpoint of drying property.

In the ink composition of the present invention, for example, for the purpose of adjusting the polarity and viscosity of the ink composition, the surface tension, the solubility and dispersibility of the coloring material, the adjustment of conductivity, and the adjustment of printing performance, a solvent is used. Can be contained. The solvent is not particularly limited as long as it has compatibility with the components constituting the ink composition of the present invention, particularly, the polymerizable monomer, and known solvents can be used.
For example, an alcohol solvent, a ketone solvent, an ester solvent, an ether solvent, a hydrocarbon solvent and the like can be mentioned. Specifically, methanol, 2-butanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran and the like can be used. These solvents may be used alone or in combination of two or more.

When the ink composition of the present invention contains a solvent, the content of the solvent is preferably 10 parts by mass or less, more preferably 1 part by mass or less, based on 100 parts by mass of the ink composition. The lower limit is not particularly limited. It is preferable that the ink composition of the present invention does not substantially contain a solvent.
In addition, "substantially does not contain" means that water or a solvent is inevitably mixed, for example, the solvent or water used in cleaning the manufacturing equipment or the like contained in the manufacturing process inevitably contains water or the solvent. It does not exclude the case of mixing.

If necessary, a storage stabilizer, a conductive salt, and other additives can be added to the ink composition of the present invention as optional components. As other additives, for example, known additives such as a polymer, an ultraviolet absorber, an antioxidant, an anti-fading agent, and a pH adjuster can be used.
As for the ultraviolet absorber, antioxidant, anti-fading agent and pH adjuster, a known compound may be appropriately selected and used, and specifically, for example, an additive described in JP-A-2001-181549. Agents and the like can be used.

  As a method for preparing the ink composition of the present invention, a conventionally known preparation method can be used. Specifically, for example, a mixture is prepared by premixing a pigment, part or all of a polymerizable monomer (or a polymerizable oligomer in the case of blending), and, if necessary, a pigment dispersant. To prepare a primary dispersion. Examples of the dispersing machine include a disperser; a container driving medium mill such as a ball mill, a centrifugal mill, and a planetary ball mill; a high-speed rotating mill such as a sand mill; and a medium stirring mill such as a stirred tank mill.

  Next, to the primary dispersion, the remaining polymerizable compound, polymerization initiator and surface conditioner, and if necessary, other additives such as an anti-gelling agent are added, and the mixture is uniformly mixed using a stirrer. Specific examples of the stirrer include a three-one motor, a magnetic stirrer, a disper, and a homogenizer. Further, the ink composition may be mixed using a mixer such as a line mixer. Furthermore, the ink composition may be mixed using a disperser such as a bead mill or a high-pressure jet mill for the purpose of making the particles in the ink composition finer.

  In order to stably discharge the ink composition on the surface of the recording medium by the ink jet method, the viscosity of the ink composition of the present invention at 25 ° C. is preferably about 3 mPa · s to 35 mPa · s. The viscosity of the ink composition can be measured using a rotary viscometer.

  Further, from the viewpoint of preventing spread and repelling of the ink composition on the surface of the recording medium, and from the viewpoint of ensuring stable continuous ejection, the surface tension of the ink composition of the present invention is about 25 to 33 mN / m. Preferably, there is. If the surface tension of the ink composition is less than 25 mN / m, repelling to the surface of the recording medium is likely to occur, and an image may not be drawn. The ink composition tends to spread on the surface, and the image may be blurred. In addition, if the above range is significantly out of the above range, the ink itself may be out of the IJP suitability, and the ink itself may have an ejection failure.

  The ink composition of the present invention has excellent stretchability after curing. For example, after printing on an olefin-based film (for example, SPM100: manufactured by Nippon Matai Co., Ltd.), at least 700% of the printed film is stretched. Has elongation. For this reason, for example, a printing film such as a marking film (a car wrapping film used for decoration of a vehicle or the like) is used to extend a printing film together with the surface of a recording medium after printing, or a printing material such as a three-dimensional three-dimensional display member is formed three-dimensionally. It is suitable for.

Therefore, in a preferred embodiment of the present invention, the ink composition of the present invention is used as an image forming ink. In particular, the ink composition of the present invention can be suitably used as an image forming ink in applications requiring large stretchability, applications such as overcoating or laminating.
In this embodiment, the ink composition of the present invention may be directly applied to the surface of a recording medium by an inkjet method.

  Further, the ink composition of the present invention has excellent adhesion to various types of recording media such as non-permeable recording media. For this reason, for example, when printing is performed using a general inkjet ink composition having relatively low adhesion to a non-permeable recording medium, the ink composition of the present invention can be used as a primer ink. .

When the ink composition of the present invention is used as a primer ink, for example, the ink composition of the present invention is applied to a recording medium by an ink-jet method to form a primer layer. Then, an image forming ink composition that is cured by irradiation with energy rays is discharged, and the ink composition is cured with the energy rays, whereby an image can be formed.
In particular, since the ink composition of the present invention can be applied by an inkjet method, when the ink composition of the present invention is used as a primer ink, at least one ink case constituting an ink set is filled with the ink composition of the present invention. By performing a printing process by a multi-pass method, formation of a primer layer and image formation can be performed in a series of processes. Naturally, the ink composition of the present invention may be applied to the recording medium in advance by using a separate coating device, and then the image may be formed with the image forming ink.

  When the ink composition of the present invention is used as a primer ink, the image forming ink used for forming an image on the primer formed with the primer ink of the present invention is not particularly limited, and a conventional ink jet system A known ink composition used for the above method can be used, but it is preferable to use an ink composition containing a polymerizable compound which is energy ray-curable and using a pigment as a coloring material.

In particular, in the case where a strength higher than the strength of the printed coating film surface obtained when the ink composition of the present invention is used as an image forming ink is required, the present invention is applied to a recording medium by an inkjet method. Forming a primer layer by applying an ink composition, and then having a high surface hardness after curing, forming an image using an image forming ink having excellent chemical resistance and abrasion resistance, It is possible to obtain a printed material having excellent adhesion to a recording medium of the above material and having high printing surface strength.
Hereinafter, an image forming ink composition particularly suitable for use with the ink composition of the present invention as a primer ink in order to obtain the above effects will be described.

  The image forming ink composition is configured to be at least a composition for forming an image. Specifically, for example, it contains at least one polymerizable compound, and if necessary, comprises a polymerization initiator, a colorant, a surface conditioner, a gelling inhibitor, other additives, and the like.

As the polymerizable compound, for example, a polymerizable compound such as a polymerizable monomer exemplified as a compound usable in the ink composition of the invention can be appropriately selected and used.
As the polymerizable compound used in the image forming ink composition, a (meth) acrylate compound and a (meth) acrylamide compound are preferable from the viewpoint of curing speed. In particular, it is preferable to mainly use a polyfunctional polymerizable compound, and it is preferable to contain a tetrafunctional or higher (meth) acrylate. Further, from the viewpoint of reducing the viscosity and improving the adhesive strength of the image forming ink composition, a trifunctional or higher polyfunctional (meth) acrylate, a monofunctional (meth) acrylate or a difunctional (meth) acrylate or (meth) It is preferable to use acrylamide in combination.

In the ink composition for image formation, the mixing ratio of the monofunctional polymerizable compound and the polyfunctional polymerizable compound is 9: 1 to 1: 9 by mass ratio (monofunctional polymerizable compound: polyfunctional polymerizable compound). It is preferably 8: 2 to 2: 8, more preferably 4: 6 to 2: 8. When the mixing ratio of the monofunctional polymerizable compound and the polyfunctional polymerizable compound is within the above range, an image forming ink composition having an appropriate curing speed and viscosity and realizing excellent surface hardness is obtained. be able to.
The content of the polymerizable compound is preferably 50 to 99.6% by mass, and more preferably 60 to 99.0% by mass, based on the solid content (mass) of the image forming ink composition.

  As the polymerization initiator, for example, the photopolymerization initiator exemplified as being usable in the ink composition of the invention can be appropriately selected and used. Specifically, from the viewpoint of curability, aromatic ketones are preferable, compounds having a benzophenone skeleton or a thioxanthone skeleton are more preferable, and α-aminoalkylphenone compounds and acylphosphine oxide compounds are particularly preferable. The polymerization initiators can be used alone or in combination of two or more. In addition, it can be used in combination with a known sensitizer for the purpose of improving sensitivity.

  It is preferable that the polymerization initiator is appropriately selected and contained within a range that can maintain the storage stability of the image forming ink composition to a desired degree. The content is, for example, preferably from 0.1 to 20% by mass, more preferably from 0.5 to 10% by mass, based on the solid content of the image forming ink composition. The content ratio of the polymerization initiator to the polymerizable compound is preferably 0.5: 100 to 30: 100 by mass ratio (polymerization initiator: polymerizable compound), and 1: 100 to 15: 100. Is more preferable.

  The image forming ink composition may include a coloring agent, a surface conditioner, an anti-gelling agent, and a sensitizer, a co-sensitizer, a storage stabilizer, a conductive salt, a solvent, and other additives depending on the purpose. May be contained. As these components, each component exemplified as being usable in the ink composition of the present invention can be appropriately selected and used.

The ink composition of the present invention can be used for various types of recording media, and exhibits good adhesion to various types of recording medium surfaces.
As the recording medium, any of a permeable recording medium, a non-permeable recording medium, and a slowly permeable recording medium can be used.

  In particular, the effects of the present invention are more remarkably exerted on non-permeable and slowly permeable recording media. Here, in the present specification, the term “penetrable recording medium” means, for example, that when 10 pL (picoliter) ink droplets are dropped on the surface of the recording medium, the time required for the entire liquid amount to penetrate is 100 hours. It refers to a recording medium that is milliseconds or less, and the “non-permeable recording medium” refers to a recording medium to which liquid droplets do not substantially penetrate. Note that “not substantially penetrate” specifically means, for example, that the penetration of the ink droplet is 5% or less one minute after the ink droplet is dropped on the surface of the recording medium. In addition, the term “slowly permeable recording medium” refers to a recording medium in which the time required for the entire liquid amount to permeate is 100 milliseconds or more when 10 pL of ink droplets are dropped on the surface of the recording medium. Say.

  Examples of the permeable recording medium include plain paper, porous paper, and other recording media that can absorb ink droplets. Examples of the non-permeable or slowly permeable recording medium include art paper, synthetic resin, rubber, resin-coated paper, glass, metal, pottery, and wood. Further, in the present invention, for the purpose of adding functions, a recording medium which is composited by combining a plurality of these materials can be used.

  As the synthetic resin, for example, polyethylene terephthalate, polyester such as polybutadiene terephthalate, polyolefin such as polyvinyl chloride, polystyrene, polyethylene, polyurethane, polypropylene, acrylic resin, polycarbonate, acrylonitrile-butadiene-styrene copolymer, diacetate, triacetate , Polyimide, cellophane, celluloid and the like.

The thickness and shape of the recording medium when using a synthetic resin are not particularly limited, and may be any of a film shape, a card shape, and a block shape, and may be either transparent or opaque. .
As the usage form of the synthetic resin, it is also preferable to use it in the form of a film used for so-called soft packaging, and various non-absorbable plastics and films thereof can be used. Examples of the plastic film include a PET film, an OPS film, an OPP film, a PNY film, a PVC film, a PE film, a TAC film, a PP film, and the like. As other plastics, polycarbonate, acrylic resin, ABS, polyacetal, PVA, rubbers and the like can be used.

  Examples of the resin-coated paper include a transparent polyester film, an opaque polyester film, an opaque polyolefin resin film, and a paper support having both sides of a paper laminated with a polyolefin resin.

  Examples of the metal include aluminum, iron, gold, silver, copper, nickel, titanium, chromium, molybdenum, silicon, lead, zinc, stainless steel, and the like, and a composite material thereof.

  The recording medium that can further exert the effect of the ink composition of the present invention is a recording medium having no particular permeability, such as an OPP film, a CPP film, PE, PET, PP, a metal plate, and a soft package having a low permeability. Materials, laminated paper, coated paper, art paper, and the like.

  The inkjet method is not particularly limited, but a charge control method for discharging ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) using a vibration pressure of a piezo element, an electric signal Acoustic ink jet system that uses radiation pressure to irradiate ink by converting light into an acoustic beam, and thermal ink jet system that heats ink to form bubbles and uses the generated pressure. The ink-jet method includes a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different densities, and a method of colorless and transparent ink. And the like.

  In the present invention, the application of energy for initiating the polymerization reaction of the polymerizable compound can be performed by irradiation with a conventionally known energy ray. As the irradiation means, an ultraviolet LED, an ultraviolet laser, or the like can be used in addition to a mercury lamp and a metal halide lamp. It is preferable to irradiate the energy composition with the energy ray after discharging the ink composition onto the surface of the recording medium until 1 to 1,000 milliseconds have elapsed. If the elapsed time is less than 1 millisecond, the distance between the head and the light source is too short, and the head may be irradiated with energy rays, which may cause an unexpected situation. On the other hand, if the elapsed time exceeds 1,000 milliseconds, the image quality tends to deteriorate due to ink bleeding when multiple colors are used.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the following, “parts” means “parts by mass”.

  Table 1 below shows the component compositions of the ink compositions used in Examples and Comparative Examples.

(Preparation of ink composition)
Example 1: Ink composition 100 ml plastic bottle was mixed with a coloring material (MA-8), a dispersant (Sol. 33000), and a polymerizable compound (HPPA, IBOA, IOA) shown in Table 2 shown in Table 2. The resulting mixture was weighed, 100 parts of zirconia beads having a diameter of 0.1 mm was added thereto, and the mixture was subjected to a dispersion treatment for 2 hours by a paint conditioner (manufactured by Toyo Seiki Co., Ltd.) to obtain a primary dispersion. Next, to the obtained primary dispersion, a photopolymerization initiator (IRGACURE907, ChivacureITX), a surface conditioner (Tegorad2100), and an anti-gelling agent (H-TEMPO) were added in the amounts shown in Table 2 and magnetically added. The mixture was stirred with a stirrer for 30 minutes. After stirring, the mixture was subjected to suction filtration using a glass filter (manufactured by Kiriyama Seisakusho) to prepare an ink composition.

Examples 2 to 14 and Comparative Examples 1 to 6 and Reference Examples 1 and 2
An ink composition was prepared in the same manner as in Example 1 so as to have the composition shown in Table 2.

  The viscosities and surface tensions of the ink compositions prepared as described above in Examples and Comparative Examples were measured by the following methods. Table 3 shows the results.

〔viscosity〕
The viscosity was measured using an R100 type viscometer (manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. and a cone rotation speed of 10 rpm.

〔surface tension〕
The surface tension at 25 ° C. was measured using a fully automatic equilibrium electro-surface tensiometer ESB-V (manufactured by Kyowa Kagaku).

1. Evaluation as Ink for Forming Image Using the following four types of recording media, the ink compositions of Examples 1 to 14 and Comparative Examples 1 to 6 and Reference Examples 1 and 2 were applied to the surface of each recording medium, The adhesion was evaluated. Table 3 shows the results.
(Recording medium)
Glass: MICRO SLIDEGLASS S9112 manufactured by Matsunami
Tiles: KEL-GEF manufactured by INAX
Acrylic board: Kuraray trading (1.0mm thickness)
Copper plate: HC336 manufactured by Hikari Co., Ltd.

Using the following films as recording media, the ink compositions of Examples 1 to 14 and Comparative Examples 1 to 6 and Reference Examples 1 and 2 were applied to the surface of each recording medium, and the elongation was measured. The stretchability of the product was evaluated. Table 3 shows the results.
(Recording medium)
Media for stretching test: SPM100 (olefin-based film) manufactured by Nippon Matai

(Image forming method)
According to the procedure described below, each ink composition was applied onto each recording medium to form an image, and a printed matter was obtained.

(A) On a recording medium, an ink solid print was produced using an ink jet recording apparatus having a piezo type ink jet nozzle, and an ink layer having a thickness of 3 μm was formed. This inkjet recording apparatus includes an ink tank, a supply pipe, a front chamber ink tank immediately before the head, and a piezo head as an ink supply system. Further, the inkjet recording apparatus was driven at a driving frequency of 10 KHz so that the ink could be ejected at a droplet size of about 7 pL and a resolution of 600 × 600 dpi.
(B) The ink layer is irradiated with ultraviolet rays using an ultraviolet LED ("NLBU21W01-E2" manufactured by Nichia Corporation) so that the total irradiation light quantity becomes 300 mJ / cm ² as the irradiation means. The layer was cured.

  The characteristics of each printed matter were evaluated by the following methods. Table 3 shows the results.

[Adhesion evaluation method]
The evaluation was performed according to "Cross-cut cellotape (registered trademark) peeling" specified in JIS K5600-5-6. The evaluation criteria were as follows.
：: 10 or less peeled portions in cross-cut test △: 11 to 20 peeled portions in cross-cut test ×: 21 or more peeled portions in cross-cut test

[Measurement of elongation]
A printed image was formed on the stretching test medium according to the above procedures (A) and (B). The printed matter obtained was cut out into a strip of 10 mm × 70 mm to obtain a test piece.
The position of 10 mm on both sides of the test piece was fixed to the sample table, and a tensile tester: AUTOGRAGH AGS-H 100N manufactured by SIMADZU was evaluated at a pulling speed of 10 mm / min. When cracks occurred in the printed portion of the test piece, the tension was stopped and the elongation was determined. The evaluation criteria were as follows. Table 3 shows the results.
A: The film was broken when stretched to 700%. No cracks or the like occurred in the printed portion other than the broken portion of the film.
：: 200% or more and less than 700% elongation ×: less than 200% elongation

  It was confirmed that each of the ink compositions of Examples 1 to 14 had excellent adhesion to glass, tile, acrylic plate and copper plate. Further, it was confirmed that a high elongation rate was realized when an image was formed on an olefin film.

2. Evaluation as a primer ink [Preparation of ink composition for forming image layer]
A colorant, a dispersant, and a polymerizable compound are weighed and measured in a 100 ml plastic bottle in the amounts shown in Table 4, and 100 parts of zirconia beads having a diameter of 0.1 mm are added thereto. The mixture is painted with a paint conditioner (manufactured by Toyo Seiki Co., Ltd.) ) To obtain a primary dispersion. Next, to the obtained primary dispersion, a photopolymerization initiator, a surface conditioner, and a gelling inhibitor were added in the amounts shown in Table 4, and the mixture was stirred for 30 minutes by a magnetic stirrer. After stirring, the mixture was subjected to suction filtration using a glass filter (manufactured by Kiriyama Seisakusho) to prepare image forming ink compositions P-1 to P-5.

(Image forming method)
On each recording medium of glass, tile, acrylic plate and copper plate, the ink composition of Example 1 was applied according to the procedure described in the above (A), and the ink composition applied according to the procedure described in the above (B) The product was cured to form a primer layer. Thereafter, an image was formed on the primer layer using the image forming ink P-1 according to the procedures described in the above (A) and (B) to obtain a printed material. Similarly, an image was formed using each of the image forming inks (P-2 to P-5) to obtain a printed material.
Further, with respect to the ink composition of Example 5, an image was formed with each image forming ink in the same manner as described above, and a printed matter was obtained.

  The obtained printed surface was evaluated for adhesion. The evaluation was performed in the same manner as the above-described evaluation method for the image forming ink composition. Table 5 shows the results obtained with the ink composition of Example 1, and Table 6 shows the results obtained with the ink composition of Example 5.

  It was confirmed that when the ink composition of the present invention was used as a primer ink, it exhibited excellent adhesion to any of glass, tile, acrylic plate and copper plate.

  According to the present invention, there is provided an energy ray-curable inkjet ink composition which has high adhesion to the surface of a recording medium made of various materials and realizes unprecedented excellent stretchability after curing. be able to.

Claims (3)

An energy ray-curable inkjet ink composition containing a polymerizable monomer and used as a primer ink,
The polymerizable monomer is a monofunctional monomer having an aromatic hydrocarbon-based cyclic structure in the molecule and a monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure in the molecule, and the aromatic hydrocarbon-based cyclic structure Containing a monofunctional monomer having a monofunctional monomer and a monofunctional monomer other than the monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure,
The monofunctional monomer having an aromatic hydrocarbon-based cyclic structure and the monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure are each composed of a monofunctional monomer having a (meth) acryloyloxy group; Monofunctional monomers other than the monofunctional monomer having a hydrocarbon-based cyclic structure and the monofunctional monomer having the aliphatic hydrocarbon-based cyclic structure are monofunctional (meth) acrylate compounds,
The monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure contains isobornyl acrylate,
The monofunctional monomer having an aromatic hydrocarbon-based cyclic structure contains 2-hydroxy-3-phenoxypropyl acrylate,
The content of the polyfunctional monomer is less than 5% by mass relative to the total amount of the polymerizable monomer;
Energy ray-curable inkjet ink composition. The energy beam curing according to claim 1, comprising a monofunctional monomer having an aromatic hydrocarbon-based cyclic structure and a monofunctional monomer having an aliphatic hydrocarbon-based cyclic structure in a mass ratio of 1:10 to 10: 1. -Type inkjet ink composition. The energy ray-curable inkjet according to claim 1, further comprising at least one photopolymerization initiator selected from the group consisting of a thioxanthone-based initiator, an acylphosphine oxide-based initiator, and an α-aminoalkylphenone-based initiator. Ink composition.