JP6479326B2 - Photocurable inkjet ink and image forming method - Google Patents

Description

  The present invention relates to a photocurable composition and a photocurable inkjet ink containing the photocurable composition, and further, a recording method using the photocurable composition, and a photocurable composition containing the photocurable composition. Recording method using an ink jet ink.

  The inkjet recording method is used in various printing fields because an image can be formed easily and inexpensively. One of the ink jet recording methods is an ultraviolet ray curable ink jet method in which droplets of ultraviolet ray curable ink are landed on a recording medium and then irradiated with ultraviolet rays to be cured to form an image. The ultraviolet curing ink jet method has recently been attracting attention because it can form an image having high abrasion resistance and adhesion even on a recording medium having no ink absorbability.

  In the method described above, since the photopolymerizable compound is photopolymerized by ultraviolet light to form a cured product on the recording medium, it is possible to improve the adhesion to the recording medium while being excellent in quick-drying property. Specifically, Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-225751), which discloses enhancing adhesion by containing a polyester resin in an ultraviolet-curable ink, and styrene or a styrene derivative as a polymer or copolymer Patent document 2 (Unexamined-Japanese-Patent No. 2013-249357) which disclosed that adhesiveness can be improved by adding the polymer component containing acrylic acid ester and acrylic acid at least one is known.

Further, Patent Document 3 (Japanese Patent Application Laid-Open No. 2012-162646) discloses that adhesion is improved by adding a polyfunctional acrylate as a polyfunctional photopolymerizable compound and adding silica fine particles and an oligomer (varnish). ) Are also known.

JP, 2011-225751, A JP, 2013-249357, A JP 2012-162646 A

  However, with the improvement of adhesion, the shrinkage of a cured product formed by the polymerization of the photopolymerizable compound which is a photopolymerizable monomer and / or a photopolymerizable oligomer by ultraviolet irradiation has become a problem. Specifically, for example, the photocurable composition applied in a non-absorptive medium is photopolymerized by ultraviolet light, and the photopolymerizable compound reacts rapidly to cause volume contraction, thereby causing shrinkage of the cured product. The problem arises that the non-absorbing recording medium is deformed. Moreover, when the polymer component of patent document 2 is added, although a cure shrinkage can be suppressed, the problem to which adhesiveness is insufficient arises.

  Therefore, the present inventors focused attention on the process of polymerization of the photopolymerizable compound by ultraviolet irradiation. Particularly in radical polymerization, it is known that curing shrinkage is remarkable by volumetric shrinkage at the time of ultraviolet irradiation, and this is caused by the fact that the photopolymerizable compound existing at van der Waals distance becomes a covalent bond after polymerization. It is believed that volumetric contraction occurs due to the difference in the bonding distance. Since the inventor of the present invention can add a partially polymerized resin to the photocurable composition by adding the photocurable resin to the photocurable composition, light containing no photocurable resin Unlike the curable composition, the volume shrinkage at the time of ultraviolet irradiation is reduced, and as a result, the curing shrinkage can be suppressed, and the photocurable resin has a photopolymerizable group, so that a substrate such as a non-absorbing substrate etc. It was found that the adhesion at

An object of the present invention is to provide a photocurable composition and a photocurable inkjet ink capable of improving the adhesion of a cured product to a non-absorptive substrate while suppressing curing shrinkage and further improving the curing sensitivity. It is to do.

In order to solve the above problems, the invention described in the paragraph (1) is
A photocurable composition containing a photopolymerizable compound and a photoinitiator, wherein the photocurable composition contains a photocurable resin having a photopolymerizable group, and the photocurable resin is the photocurable resin. While having a methacrylate or / and an acrylate having a polymerizable group, the molecular weight of the photocurable resin is 10000 or more and 150000 or less,
The photocurable resin is contained in an amount of 5 or more and 40% by mass or less based on the total mass of the photocurable composition.

The invention described in the item (2) is the photocurable composition described in the item (1),
An equivalent of the photopolymerizable group of the photocurable resin is 100 or more and 1000 or less.

The invention described in the item (3) is the photocurable composition described in the item (1) or (2),
The molecular weight of the photocurable resin is 10000 or more and 70000 or less.

The invention described in the item (4) is the photocurable composition described in any one of the items (1) to (3),
It is characterized in that the equivalent of the photopolymerizable group of the photocurable resin is 100 or more and 500 or less.

The invention described in item (5) is the photocurable composition described in any one of items (1) to (4),
The photocurable composition contains an organic solvent, and the organic solvent is 3% by mass or less based on the total mass of the photocurable composition.

The invention described in item (6) is
A photocurable ink jet ink comprising the photocurable composition according to any one of items (1) to (5).

  The invention described in the item (7) is characterized in that, in the photocurable inkjet ink described in the item (6), the ink-jet ink contains a coloring material.

The invention described in Item (8) is the photocurable inkjet ink described in Item (7),
A pigment is contained as the coloring material, and a pigment dispersant is further contained.

The invention described in item (9) relates to a recording method using a photocurable composition,
After applying the photocurable composition according to any one of items (1) to (5) to a recording medium, the composition is irradiated with an actinic ray to cure the photocurable composition. I assume.

The invention described in Item (10) is the recording method using the photocurable composition described in Item (8),
The recording medium is any of polypropylene, polyethylene and polyethylene terephthalate.

The invention according to item (11) relates to a recording method using a photocurable inkjet ink,
An inkjet head for ejecting the photocurable inkjet ink according to any one of (6) to (8).
An irradiation unit for irradiating an actinic ray,
A transport unit for transporting the recording medium;
Recording method using a photocurable inkjet ink in an inkjet recording apparatus comprising
After the photocurable inkjet ink is applied to the recording medium by the inkjet head, the photocurable inkjet ink is cured by irradiation with an actinic ray by the irradiation unit.

The invention described in Item (12) is the recording method using the photocurable inkjet ink described in Item (10),
The recording medium is any of polypropylene, polyethylene and polyethylene terephthalate.

  ADVANTAGE OF THE INVENTION According to this invention, the photocurable composition and photocurable inkjet ink which can improve the adhesiveness of the hardened | cured material with respect to a base material, and also can aim at the improvement of hardening sensitivity are provided, suppressing hardening shrinkage.

FIG. 1 is a view showing an essential part of an example of an ink jet recording apparatus used in the present invention. FIG. 6 is a view showing the main parts of another example of the ink jet recording apparatus used in the present invention.

  The photocurable composition in the present invention is, for example, one that applies a primer layer before forming an image on a substrate by an inkjet or the like, and enables image formation on a non-absorbing recording medium. In addition, by incorporating a coloring material such as a pigment into the above-described photocurable composition, a photocurable inkjet ink capable of forming a high-definition image on a medium can also be obtained. Below, the photocurable composition mentioned above is explained in full detail.

[Photopolymerizable compound]
The photopolymerizable compound in the present invention is a compound that is photopolymerized to be a cured product when irradiated with ultraviolet light, and any known photopolymerizable monomer and / or photopolymerizable oligomer can be used. In the present invention, "and / or" means that it may be a photopolymerizable monomer or an oligomer, and may further include both. In the following description, any monomer or oligomer is referred to as a photopolymerizable compound.

  In the present invention, radically polymerizable monomers and / or cationically polymerizable monomers can be used as the photopolymerizable compound.

As a radically polymerizable monomer, for example, a compound having a (meth) acrylate group is used. Among them, an acrylate compound is preferably used from the viewpoint of curability. Specifically, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomystyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrate Hydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl Acrylate 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid, lactone-modified flexible acrylate, monofunctional monomers such as t-butyl cyclohexyl acrylate;
Triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate Difunctional monomers such as dimethylol-tricyclodecane diacrylate, PO adduct diacrylate of bisphenol A, neopentyl glycol diacrylate hydroxypivalate, and polytetramethylene glycol diacrylate;
Trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxy triacrylate, caprolactone modified trimethylol propane triacrylate, pentaerythritol ethoxy tetraacrylate, caprolactam modified di Trifunctional or higher polyfunctional monomers such as pentaerythritol hexaacrylate;
Methacryl such as methyl methacrylate, n-butyl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane and the like Derivatives are included. More specifically, Yamashita Toshi 3 ed., "Crosslinking agent handbook", (1981 Taiseisha); Kato Seiyo ed., "UV · EB curing handbook (raw material ed.)" (1985, Polymer Journal), Rad Tech Journal of the research group, “Application and market of UV / EB curing technology”, page 79 (1989, CMC); written by Eiichiro Takiyama, “Polyester resin handbook”, (1988, Nikkan Kogyo Shimbun Co., Ltd.), etc. Commercially available products or photopolymerizable monomers known in the art can be used.

  Besides these, polymerizable oligomers can also be blended in the same manner as the monomer. Examples of the polymerizable oligomer include epoxy acrylates, aliphatic urethane acrylates, aromatic urethane acrylates, polyester acrylates and linear acrylic oligomers.

  In addition, since radically polymerizable monomers are covalently bonded together with the photopolymerizable group of the photocurable resin described later in detail when irradiated with ultraviolet light to form a cured product, compared with other photopolymerizable compounds. It is preferable in the viewpoint which improves the adhesiveness of the hardened | cured material with respect to a base material more.

  On the other hand, as a cationically polymerizable monomer, for example, a styrene derivative, vinyl ether, oxirane, oxetane, tetrahydrofuran, lactam, lactone compound and the like are used. Among them, oxirane, oxetane, vinyl ether compounds or styrene derivatives are preferably used, and in particular vinyl ether compounds are preferably used from the viewpoint of curability.

  Among vinyl ether compounds, examples of monofunctional vinyl ether compounds 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, cyclohexyl vinyl ether, Cyclohexylmethylvinylether, 4-methylcyclohexylmethylvinylether, benzylvinylether, dicyclopentenylvinylether, 2-dicyclopentenoxyethylvinylether, methoxyethylvinylether, ethoxyethylvinylether, butoxyethylvinylether, methoxyethoxyethylvinylether, ethoxyethoxyethylvinylether , Metki Polyethylene glycol vinyl ether, tetrahydrofrillyl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethyl cyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chlorethyl vinyl ether, chlorobutyl vinyl ether And chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxy polyethylene glycol vinyl ether and the like.

  Also, as examples of polyfunctional vinyl ether compounds, for example, 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 Divinyl ethers such as F alkylene oxide divinyl ether; trimethylol ethane trivinyl ether, trimethylol propane trivinyl ether, ditrimethylol propane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol Tall hexavinyl ether, ethylene oxide addition 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 Multifunctional vinyl ethers such as addition pentaerythritol tetravinyl ether, ethylene oxide addition dipentaerythritol hexavinyl ether, propylene oxide addition dipentaerythritol hexavinyl ether, cyclohexane dimethanol divinyl ether (CHDMVE), triethylene glycol Over distearate ether (TEGDVE), and the like.

  As the oxirane compound, any known epoxy compound (epoxide) can be used.

  Examples of monofunctional epoxides include, for example, phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene mono Oxides, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, 3-vinylcyclohexene oxide, etc. It can be mentioned.

  Examples of polyfunctional epoxides include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, brominated bisphenol S diglycidyl Ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexane carboxylate (celloxide 2021 P (manufactured by Daicel Corporation), 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxa Bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl 3 ', 4'-Epoxy-6'-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, di (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylene bis 3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1, 6 Hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1,2 And 7,8-diepoxyoctane, 1,2,5,6-diepoxycyclooctane and the like.

  Moreover, as a compound (oxetane compound) which has an oxetane ring, all well-known oxetane compounds which are introduced by Unexamined-Japanese-Patent No. 2001-220526, 2001-310937 can be used together.

  Examples of monofunctional oxetanes such as 3-ethyl-3-hydroxymethyl oxetane, 3- (meth) allyloxymethyl-3-ethyl oxetane, (3-ethyl-3-oxetanyl methoxy) methyl, and oxetane compounds are exemplified. Benzene, 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, 4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-) Ethyl-3-oxetanylmethoxy) ethyl] phenylether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl- 3-oxetanylmethyl) ether, 2-ethylhexyl (3- Ru-3-oxetanylmethyl) ether, ethyl diethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3-ethyl-3-ethyl) Oxetanylmethyl) ether, dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl (3-ethyl-3-oxeta) Rumethyl) ether, 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl-3-oxetanylmethyl) ether, Pentachlorophenyl (3-ethyl-3-oxetanylmethyl) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanylmethyl) ether and the like can be mentioned.

  Moreover, as a polyfunctional oxetane compound, for example, 3,7-bis (3-oxetanyl) -5-oxa-nonane, 3,3 '-(1,3- (1,2- (2-methylenyl) propanediyl bis (oxymethylene)) Bis- (3-ethyloxetane), 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1 , 3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl bis (3-ethyl-3-oxetanylmethyl) ether, Triethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis (3 Ethyl-3-oxetanylmethyl) ether, tricyclodecanediyldimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether, 1,4-bis (3) -Ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis (3-ethyl- 3-oxetanylmethyl) ether, polyethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol pentakis (3- Ethyl-3-oxetanylmethyl) ether, dipentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone modified dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone modified dipentaerythritol pentamer Kiss (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropane tetrakis (3-ethyl-3-oxetanylmethyl) ether, EO modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO modified bisphenol A Bis (3-ethyl-3-oxetanylmethyl) ether, EO modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO modified hydrogenated bisphenol A bis (3 Mention may be made of polyfunctional oxetanes such as -ethyl-3-oxetanylmethyl) ether and EO-modified bisphenol F (3-ethyl-3-oxetanylmethyl) ether.

  The content of the photopolymerizable compound can be appropriately set according to the addition amount of the photocurable resin described later, but the content is 60% by mass or more and 90% by mass or less based on the total mass of the photocurable composition. Is preferred.

[Photo initiator]
The photoinitiator (photopolymerization initiator) according to the present invention is capable of initiating polymerization of a polymerizable compound by light, and as the photoinitiator, “application and market of UV / EB curing technology” (CMCC) Any of the known photoinitiators described in the publication, edited by T. Tabata (edited by Radtech Research Group), etc. can be used.
As a photoinitiator, a radical polymerization initiator and a cationic polymerization initiator can be mentioned.

  The radical polymerization initiator contained in the photocurable composition of the present invention may be either a molecular cleavage type or a hydrogen abstraction type. Preferred specific examples of the radical polymerization initiator include benzoin isobutyl ether, 2,4-diethyl thioxanthone, 2-isopropyl thioxanthone, benzyl, 2,4,6-trimethyl benzoyl diphenyl phosphine oxide, 2-benzyl-2-dimethylamino- 1- (4-morpholinophenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentyl phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenyl phosphine Oxide and the like are included.

  Further, examples of other radical cleavage type radical polymerization initiators include 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1 -(4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 1- [4- (2) And -hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one and the like. Further, examples of hydrogen abstraction type photoinitiators include benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4'-methyl-diphenyl sulfide, and metallocene-type polymerization initiator bis (2,4-cyclo). Pentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium, an oxime ester type polymerization initiator, 1,2-octanedione, 1- ( 4- (phenylthio) -2- (O-benzoyloxime)), ethanone, 1- (9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl) -1- (O-acetyloxime Etc.).

Moreover, you may contain a sensitizer with a radical polymerization initiator. Examples of sensitizers include trimethylamine, methyldimethanol amine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzylamine and 4, Included are amines that do not undergo addition reaction with photopolymerizable compounds, such as 4'-bis (diethylamino) benzophenone. Of course, the radical polymerization initiator and the sensitizer are preferably excellent in the solubility in the photopolymerizable compound.
The content of the radical polymerization initiator and the sensitizer is in the range of 0.1 to 20% by mass, preferably 1 to 12% by mass, with respect to the total mass of the photocurable composition.

In addition, a type in which an amine starting auxiliary is attached as an initiator structure to a dendrimer core described in European Patent No. 1,674,499 A, European Patent No. 2,161,264 A, European Patent No. The initiator having a polymerizable group described in 2,189,477A, an amine-based start aid, and a plurality of amine-based start aids described in European Patent No. 1,927,632 B1 are contained in one molecule. The type having a plurality of thioxanthones in the molecule described in WO 2009/060235, and the alpha hydroxy propiophenone represented by ESACURE ONE commercially available from Lamberti, represented by ESACUR KIP 150. An oligomer type polymerization initiator or the like bonded to a chain can also be preferably used.

  Also, the maleimide-containing polymerizable monomer itself can function as an initiator.

  On the other hand, in the case of using a cationic polymerization monomer, for example, a cationic amplification initiator used for a chemically amplified photoresist or photo cationic polymerization is used (Organic Electronics Materials Research Committee, "organic material for imaging", Bunshin Publishing Co., Ltd.) (1993), pages 187-192). Examples of compounds suitable for the present invention include B (C6F5) 4-, PF6-, AsF6-, SbF6-, CF3SO3-salts and sulfonic acids of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium and the like And halides that photogenerate hydrogen halides, and iron allene complexes.

[Photo-curable resin]
The photocurable resin of the present invention has a methacrylate or / and an acrylate having a photopolymerizable group. The photopolymerizable group is a group having a reactive double bond which causes a polymerization reaction by reacting with radicals generated when the radical polymerization initiator is irradiated with ultraviolet light and the like. As a photocurable resin of this invention, the polymer type acrylate which has a (meth) acryl group in a side chain can be mentioned, for example. As the polymer type acrylate, either a commercial product or a synthetic product may be used, and in the case of the commercial product, a polymer type acrylate resin (manufactured by Taisei Fine Chemical Co., Ltd .: 8KX polymer series), (Hitachi Chemical Co., Ltd .: Hitachiloid series), (DI Corporation: Unidic Series), (Mitsubishi Chemical Corporation: Yupimar Series), etc. can be used, but not limited thereto.

  In the case of a synthetic product, reference can be made to known synthetic examples. For example, Unexamined-Japanese-Patent No. 2006-335837 is mentioned. That is, a polymer obtained by copolymerizing a (meth) acrylic acid ester monomer containing a functional group (acid and epoxy) and an acrylic macromonomer by radical polymerization or the like in a first step solvent is prepared, and a second step epoxy or acid The (meth) acrylic acid ester-based monomer of the above is obtained by the addition reaction of the first-stage polymerized polymer. In addition, it is not limited to the synthesis example mentioned above.

  By containing the photocurable resin described above, the adhesion of the cured product to the substrate can be improved while suppressing curing shrinkage, and the curing sensitivity can be further improved. The inventors consider the reason for the above-mentioned effect as follows.

  The photocurable composition containing only the photopolymerizable compound shows remarkable curing shrinkage, but this is because the photopolymerizable compound existing at van der Waals distance is covalently bonded after being polymerized by irradiation of ultraviolet light. It is considered that the resin becomes a cured product, and the difference in the bonding distance causes contraction. Therefore, by incorporating the photocurable resin in the present invention into the photocurable composition, it is possible to add a partially polymerized resin in comparison with a photocurable composition containing only a photopolymerizable compound. Therefore, unlike the photopolymerizable compound alone system, it is presumed that the volumetric shrinkage at the time of ultraviolet irradiation decreases, and as a result, the shrinkage of the cured product can be suppressed. Moreover, since a photocurable resin can be covalently bonded to a photopolymerizable compound by having a photopolymerizable group, adhesion to a substrate can be imparted in addition to the suppression of the cure shrinkage described above. . In addition, by incorporating the photocurable resin in the photocurable composition, it is possible to impart adhesiveness which is excellent in hard coatability particularly to the non-absorptive substrate inherent to the photocurable resin. Specifically, the chemical affinity between the non-absorbent substrate and the cured product is improved, and the adhesion is improved. Furthermore, it is estimated that the photocurable resin is excellent in photocurability because the photocurable resin has a photopolymerizable group so that the reactivity with the photopolymerizable compound in the photocurable composition is not broken.

  The molecular weight of the photocurable resin can be suitably used as long as it is 10000 or more and 150000 or less, but when the photocurable composition of the present invention is contained in an inkjet ink and used as a photocurable inkjet ink It is more preferable to set the molecular weight to 10000 or more and 70000 or less from the viewpoint of favorably ejecting the curable inkjet ink from the nozzle. Moreover, as content of photocurable resin, 5 mass% or more and 40 mass% or less are preferable with respect to the total mass of a photocurable composition.

  The equivalent weight of the photopolymerizable group of the photocurable resin is 100 or more and 1000 or less from the viewpoint of facilitating bonding with the photopolymerizable compound or the photocurable resin and improving the hardness to improve the adhesion. It can be used suitably, More preferably, it is 100 or more and 500 or less.

[Radical polymerization inhibitor]
The photocurable composition of the present invention preferably further contains a radical polymerization inhibitor from the viewpoint of storage stability.

Examples of radical polymerization inhibitors include phenolic hydroxyl group-containing compounds, quinones or hydroquinones, phenothiazines, N-oxyls, aromatic amines or phenylenediamines, imines, sulfonamides, oximes, hydroxylamines, urea derivatives (for example, urea) Or thiourea), phosphorus-containing compounds (eg, triphenylphosphine, triphenyl phosphite, hypophosphorous acid, torinyl phosphite, triethyl phosphite or diphenylisopropyl phosphine), sulfur-containing compounds (eg, diphenyl sulfide, phenothiazine), And sulfur-containing natural substances (eg, cysteine) and the like.

Complexing agents based on tetraazaannulene (TAA) are described, for example, in Chem. So
c. Rev. 1998, 27, 105-115, for example, dibenzotetraaza [14] ring and porphyrin.

In addition, metal salts (copper, manganese, cerium, nickel, chromium, etc.) such as carbonic acid, chloride, dithiocarbamic acid, sulfuric acid, salicylic acid, acetic acid, stearic acid, ethylhexanoic acid and the like can be mentioned.

Further, the N-oxyl free radical compound having a vinyl ether functional group described in Macromol. Rapid Commun., 28, 1929 (2007) has a structure having a polymerizable function and a radical scavenging function in the same molecule, and has a curability and From the viewpoint of the preservability of the photocurable composition, it is preferable to add it to the photocurable composition of the present invention. Further, a polymer obtained by polymerizing the N-oxyl free radical compound having a vinyl ether functional group is a polymer having a structure having a free radical in a side chain, and curing such as solvent resistance, abrasion resistance and weather resistance It is preferable to add from the viewpoint of film physical properties and storage stability of the photocurable composition.

  The content of the radical polymerization inhibitor in the photocurable composition of the present invention is preferably 1.0 or more and 5,000 μg / g or less, and 10 or more and 2,000 μg / g or less. Or less is more preferable. If it is 1.0 μg / g or more of the photocurable composition, the cure shrinkage of the formed image can be effectively suppressed. In addition, desired photocurable composition storage stability can be obtained, and in particular, suppression of thickening of the inkjet ink containing the photocurable composition and liquid repellency to the inkjet nozzle can be obtained, from the viewpoint of discharge stability Preferred. Further, if it is 5,000 μg / g or less, it is preferable from the viewpoint of maintaining high curing sensitivity without impairing the acid radical generation efficiency of the polymerization initiator when using a photo radical polymerization initiator in combination.

[Cationic polymerization inhibitor]
In the photocurable composition of the present invention, a cationic polymerization inhibitor is preferably blended together with the radical polymerization inhibitor.

Examples of the cationic polymerization inhibitor include alkali metal compounds, alkaline earth metal compounds and amines.

Preferred amines as cationic polymerization inhibitors include alkanolamines, N, N-
And dimethylalkylamines, N, N-dimethylalkenylamines, N, N-dimethylalkynylamines and the like. Specifically, triethanolamine, triisopropanolamine, tributanolamine, N-ethyldiethanolamine, propanolamine, n-butylamine, sec-butylamine, 2-aminoethanol, 2-methylaminoethanol, 3
-Methylamino-1-propanol, 3-methylamino-1,2-propanediol, 2-ethylaminoethanol, 4-ethylamino-1-butanol, 4- (n-butylamino) -1-butanol, 2- (T-butylamino) ethanol, N, N-dimethylundecanol, N, N-dimethyldodecanolamine, N, N-dimethyltridecanolamine, N, N-dimethyltetradecanolamine, N, N- Dimethylpentadecanolamine, N, N-Dimethyl nonadecylamine, N, N-Dimethyl icosylamine, N, N-Dimethyl eicosyl amine, N, N-Dimethyl henicosyl amine, N, N-Dimethyl docosyl Amine, N, N-dimethyltricosylamine, N, N-dimethyltetracosylamine, N, N-dimethylpentacosylamine, N,
N-dimethylpentanolamine, N, N-dimethylhexanolamine, N, N-dimethylheptanolamine, N, N-dimethyloctanolamine, N, N-dimethylnonanolamine, N, N-dimethyldecanolamine N, N-dimethylnonylamine, N, N-dimethyldecylamine, N, N-dimethylundecylamine, N, N-dimethyldodecylamine, N,
N-Dimethyltridecylamine, N, N-Dimethyltetradecylamine, N, N-Dimethylpentadecylamine, N, N-Dimethylhexadecylamine, N, N-Dimethylheptadecylamine, N, N-Dimethyloctadecylamine Can be mentioned. Besides these, quaternary ammonium salts can also be used. Among them, 2-methylaminoethanol is preferable because the storage stability can be improved without decreasing the curability by the addition of a small amount.

  The content of the cationic polymerization inhibitor in the photocurable composition of the present invention is preferably 0.1 μg / g or more photocurable composition or more and 50 μg / g or less photocurable composition or less. By setting the content to 0.1 μg / g or more of the photocurable composition, the cure shrinkage of the formed image can be effectively suppressed. In addition, good storage stability of the photocurable composition can be obtained, and in particular, suppression of thickening of the ink jet ink containing the photocurable composition and good liquid repellency to the ink jet nozzle can be obtained, and discharge stability is maintained. It is preferable at the point which can be done. Further, by setting the concentration to 50 μg / g or less of the photocurable composition, it becomes possible to sufficiently maintain the acid radical generation efficiency of the photoradical polymerization initiator when using the photoradical polymerization initiator in combination, and the curing sensitivity is maintained. Preferred above.

[Color material]
The photocurable composition may further contain a colorant, if necessary. The colorant may be a dye or a pigment, but is preferably a pigment because it has good dispersibility with respect to the components of the ink and is excellent in weather resistance. The pigment is not particularly limited. For example, organic pigments or inorganic pigments of the following numbers described in Color Index can be used.
As the pigment, for example, colorless inorganic pigments such as carbon black, titanium oxide and calcium carbonate or colored organic pigments can be used. Examples of organic pigments include insoluble azo pigments such as toluidine red, toluidine maroon, Hansa yellow, benzidine yellow and pyrazolone red, soluble azo pigments such as lithole red, helio Bordeaux, pigment scarlet and permanent red 2B; alizarin, indanthrone, Derivatives from vat dyes such as thioindigo maroon; Phthalocyanine-based organic pigments such as phthalocyanine blue and phthalocyanine green; Quinacridone-based organic pigments such as quinacridone red and quinacridone magenta; perylene-based organic pigments such as perylene red and perylene scarlet; Isoindolinone-based organic pigments such as linon yellow and isoindolinone orange; pyranthrone-based organic pigments such as pyranthrone red and pyranthrone orange; thioin Organic pigments, condensed azo organic pigments, benzimidazolone organic pigments, quinophthalone organic pigments such as quinophthalone yellow; isoindoline organic pigments such as isoindoline yellow; other pigments such as flavanthrone yellow, acylamide yellow Nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianthraquinonil red, dioxazine violet and the like.

  The organic pigments are exemplified below by color index (CI) numbers.

C. I. Pigment yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 110, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185,
C. I. Pigment orange 16, 36, 43, 51, 55, 59, 61,
C. I. Pigment red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 177, 180, 192, 202, 206, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240,
C. I. Pigment violet 19, 23, 29, 30, 37, 40, 50,
C. I. Pigment blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64,
C. I. Pigment green 7, 36,
C. I. Pigment brown 23, 25, 26,

Among the above pigments, quinacridone pigments, phthalocyanine pigments, benzimidazolone pigments, isoindolinone pigments, condensation azo pigments, quinophthalone pigments, isoindoline pigments, and the like are preferable because of their excellent light resistance.

  The organic pigment preferably has an average particle size in the ink of 10 nm to 150 nm as measured by laser scattering. When the average particle size of the pigment is less than 10 nm, the reduction of the particle size may cause a decrease in light resistance. When it exceeds 150 nm, it becomes difficult to maintain the stability of the dispersion and precipitation of the pigment tends to occur, and particularly when used in an inkjet ink, the ejection stability decreases and a problem of generation of a minute mist called satellite occurs. Sometimes. However, in the case of titanium oxide, the average particle diameter is 150 nm or more and 300 nm or less, preferably 180 nm or more and 250 nm or less, in order to give whiteness and concealability.

  Further, it is preferable to remove coarse particles by sufficient dispersion or filtration so that the maximum particle size of the pigment in the inkjet ink does not exceed 1.0 μm. The presence of coarse particles also tends to reduce the ejection stability.

The refinement of the organic pigment can be carried out by the following method. That is, 3 of organic pigments and organic pigments
A mixture consisting of at least three components of a water-soluble inorganic salt and a water-soluble solvent at a mass ratio of at least three components is formed into a clay and finely kneaded with a kneader etc. to be finely divided and then put into water and stirred by a high speed mixer etc. It will be in the form of The slurry is then filtered and washed repeatedly to remove water-soluble inorganic salts and water-soluble solvents by aqueous treatment. In the refining process, a resin, a pigment dispersant and the like may be added.

Examples of water-soluble inorganic salts include sodium chloride and potassium chloride. These inorganic salts are used in a range of 3 to 20 times by mass of the organic pigment, but after dispersion treatment, the chloride ion (halogen ion) is washed with water to achieve the halogen ion content specified in the present invention Perform removal operation by processing. If the amount of the inorganic salt is less than 3 times by mass, a treated pigment of a desired size can not be obtained, and if it is more than 20 times by mass, the washing treatment in the later step is extensive and the substance of the organic pigment Throughput is reduced.

The water-soluble solvent is not particularly limited as long as it is a solvent that dissolves in water and is used to form a proper clay state of an organic pigment and a water-soluble inorganic salt used as a crushing aid and to perform sufficient crushing efficiently. However, since the temperature rises during kneading and the solvent is easily evaporated, a solvent having a high boiling point of 120 or more and 250 ° C. or less is preferable from the viewpoint of safety. As a water-soluble solvent, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (i-pentyloxy) ethanol, 2- (hexyloxy) ethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether , Triethylene glycol, triethylene glycol monomethyl ether, liquid polyethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, low molecular weight Polypropylene glycol etc. are mentioned.

Moreover, in order to promote adsorption of the pigment on the surface with the pigment dispersant, it is preferable to perform surface treatment by known techniques such as acid treatment or basic treatment, synergist, various coupling agents, etc. to ensure dispersion stability. Preferred.

  In order to obtain sufficient concentration and sufficient light resistance, the pigment is 1.5 to 8% by mass in the case of a color except white in the photocurable composition, and 10 to 30% in the case of a white ink using titanium oxide. It is preferable to include in the range of%.

[Pigment dispersant]
It is preferable to include a pigment dispersant for dispersing the above-described pigment in the photocurable composition. As pigment dispersants, hydroxyl group-containing carboxylic acid esters, salts of long chain polyaminoamide and high molecular weight acid ester, salts of high molecular weight polycarboxylic acid, salts of long chain polyaminoamide and polar acid ester, high molecular weight unsaturated acid ester, Polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic surfactant, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl Phenyl ether, stearylamine acetate, pigment derivatives and the like can be mentioned.

As specific examples, "Anti-Terra-U (polyaminoamide phosphate)", "Anti-Terra-203 / 204 (high molecular weight polycarboxylate)" manufactured by BYK Chemie, "Disperbyk-101 (polyaminoamide phosphoric acid)" Salt and acid ester)
, 107 (hydroxy group-containing carboxylic acid ester), 110 (copolymer containing an acid group), 130 (130
Polyamide), 161, 162, 163, 164, 165, 166, 170 (polymer copolymer) "," 400 "," Bykumen "(high molecular weight unsaturated acid ester)," BYK
-P104, P105 (high molecular weight unsaturated acid polycarboxylic acid) "," P104 S, 240 S
(High molecular weight unsaturated acid polycarboxylic acid and silicone type) "Lactimon (long chain amine and unsaturated acid polycarboxylic acid and silicone)" can be mentioned.

In addition, “Efka 44, 46, 47, 48, 49, 5” manufactured by Efka CHEMICALS.
4, 63, 64, 65, 66, 71, 701, 764, 766 "," Efka Polymer 10
0 (modified polyacrylate), 150 (aliphatic modified polymer), 400, 401, 40
2, 403, 450, 451, 452, 453 (modified polyacrylate), 745 (copper phthalocyanine type) ";" Floren TG-710 (urethane oligomer) manufactured by Kyoei Kagaku Co., Ltd. "
“Flowon SH-290, SP-1000”, “Polyflow No. 50E, No.
300 (acrylic copolymer) "Dispalon KS-860, 873" manufactured by Kushimoto Chemical Co., Ltd.
SN, 874 (polymer dispersant), # 2150 (aliphatic polyvalent carboxylic acid), # 7004 (polyether ester type) and the like.

Furthermore, “Demol RN, N (Naphthalene sulfonic acid formalin condensate sodium salt), MS, C, SN-B (aromatic sulfonic acid formalin condensate sodium salt) manufactured by Kao Corporation,
EP "," homogenol L-18 (polycarboxylic acid type polymer) "," Emulgen 920,
930, 931, 935, 950, 985 (polyoxyethylene nonyl phenyl ether) "," Acetamine 24 (coconut amine acetate), 86 (stearyl amine acetate) ";" Sor Spars 5000 (phthalocyanine ammonium salt system) "manufactured by Zeneka
13240, 13940 (polyester amine type), 17000 (fatty acid amine type),
24000, 32000, 7000 ′ ′; “Nikkole T106 (polyoxyethylene sorbitan monooleate), MYS-IEX (polyoxyethylene monostearate), Hexagline 4-0 (hexaglyceryl tetraoleate)” manufactured by Nikko Chemical Co., Ajinomoto fine techno Manufactured by AISPER 821, 822, 824 and the like.

These pigment dispersants are preferably contained in an amount of 5 to 70% by mass, preferably 10 to 50% by mass, with respect to 100 of the pigment. If it is less than 5%, dispersion stability may be difficult to obtain, and if it is more than 70%, for example, in the case of using in an inkjet ink, the ejection stability may be deteriorated.

Furthermore, it is preferable that these pigment dispersants have a solubility of 5% by mass or more in the entire cationically polymerizable monomer at 0 ° C. If the solubility is less than 5% by mass, when the photocurable composition is stored at a low temperature between about 0 ° C. and 10 ° C., soft aggregates of an undesirable polymer gel or pigment may be generated. While the storage stability of a photocurable composition deteriorates, when using for inkjet ink, discharge stability may deteriorate.

[Organic solvent]
Small amounts of solvents such as ester solvents, ether solvents, ether ester solvents, ketone solvents, aromatic hydrocarbon solvents, nitrogen-containing organic solvents and the like may be included. The content of the organic solvent is preferably 0.2% by mass or more and 5% by mass or less with respect to the mass of the entire photocurable composition from the viewpoint of photocurability and the environment.

Further, as described above, while the curability can be improved as the content of the organic solvent is reduced, the influence of the cure shrinkage becomes remarkable. In the present invention, the adhesiveness can be improved while suppressing the cure shrinkage by containing the photocurable resin even with respect to the cure shrinkage that occurs more significantly when the content of the organic solvent is reduced.

[Other additives]
The photocurable composition of the present invention is for the purpose of improving the emission stability, print head and ink packaging container compatibility, storage stability, image storage property, and other various properties, as needed, in addition to the above description. Accordingly, various known additives, for example, surfactants, lubricants, fillers, antifoaming agents, gelling agents, thickeners, resistivity modifiers, film forming agents, UV absorbers, antioxidants, discoloration It is possible to appropriately select and use an inhibitor, a rust inhibitor, a rust inhibitor and the like.

Specific examples of various additives include dimethylsulfoxide, diethylsulfoxide, methylethylsulfoxide, diphenylsulfoxide, tetraethylenesulfoxide, dimethylsulfone, methylethylsulfone, methyl-isopropylsulfone, methyl-hydroxyethylsulfone, sulfolane, or N- Methyl-2-pyrrolidone, 2-pyrrolidone, β-lactam, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, 3-methyl -2-oxazolidinone,
γ-butyrolactone, γ-valerolactone, isophorone, cyclohexanone, propylene carbonate, anisole, methyl ethyl ketone, acetone, ethyl lactate, butyl lactate, dioxane, ethyl acetate, butyl acetate, diethylene glycol dimethyl ether, dibasic acid ester, methoxybutyl acetate, etc. Can be mentioned. When these are added in an amount of 1.5 to 30% by mass, preferably 1.5 to 15% by mass, in the ink, the adhesion to a resin recording medium such as polyvinyl chloride is improved.

Other specific examples of various additives include: diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, alkylene glycol monoalkyl ethers such as tripropylene glycol monomethyl ether, ethylene glycol dibutyl ether, tetraethylene glycol Alkylene glycol dialkyl ethers such as dimethyl ether, alkylene glycol monoalkyl ether acetates such as ethylene glycol monobutyl ether acetate, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, ethylene glycol diacetate, propylene glycol diacetate, etc. Listed .

  Moreover, as surfactant which can be used for the photocurable composition of this invention, anionic surfactant, such as dialkyl sulfo succinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, Nonionic surfactants such as polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, etc. Cationic surfactants such as alkylamine salts, quaternary ammonium salts, silicone type A fluorine type surfactant is mentioned, Especially a silicone type or fluorine type surfactant is preferable.

By adding a silicone-based or fluorine-based surfactant, it is possible to further suppress the ink mixing to a recording medium composed of various hydrophobic resins such as a vinyl chloride sheet, and a recording medium such as a printing paper, which absorbs slowly. High quality printed images. The surfactant is particularly preferably used in combination with the low surface tension water-soluble organic solvent.

The silicone surfactant is preferably a polyether-modified polysiloxane compound, for example, KF-351A, KF-642, X-22-427 manufactured by Shin-Etsu Chemical Co., Ltd.
2 and Big Chemie made BYK 307, BYK 345, BYK 347, BYK 348, and TSF 4452 made by Toshiba Silicone Co., Ltd.

The fluorine-based surfactant means a part or all of which is substituted with fluorine, instead of hydrogen bonded to carbon of the hydrophobic group of a normal surfactant. Among these, those having a perfluoroalkyl group in the molecule are preferable.

Of fluorine-based surfactants, some of them are Megafac from DIC (Megafa
c) Under the trade name F, from Asahi Glass Co., Ltd. under the trade name Surflon, and from Minnesota Mining and Manufacturing Company, Inc. Fluorad (F
luorad) FC under the trade name Imperial Chemical Industries, Inc. under the trade name Monflor, E. I. Dupont Nemeras &
It is commercially available under the tradename Zonyls from Company, or under the tradename Licowet VPF from Rubberge-Hoechst, and under the tradename tradename from Neos.

  The addition amount of the surfactant is preferably 0.1% by mass or more and less than 2.0% by mass with respect to the total mass of the photocurable composition.

[Physical Properties of Photocurable Composition]
The viscosity at 25 ° C. of the photocurable composition is preferably 10 m · pas or more and 500 m · pas or less from the viewpoint of handling such as ease of spreading when the photocurable composition is applied by a bar coder or the like. The surface tension can be appropriately adjusted and used according to the recording medium to be coated.

[Method for adjusting photocurable composition]
The photocurable composition of the present invention can be appropriately diluted with a photopolymerizable compound in order to contain a photocurable resin. For example, in the case of using a photocurable resin diluted in an organic solvent, it can be used by diluting the solvent with a photopolymerizable compound in advance and then evaporating the solvent under reduced pressure. Moreover, although mentioned later, a photocurable inkjet ink can also be obtained by using the photocurable composition obtained here.

[Physical Properties of Photocurable Inkjet Ink Containing Photocurable Composition]
Next, the photocurable inkjet ink containing the photocurable composition of the present invention will be described in detail. If the surface tension of the photocurable inkjet ink in the present invention is 15 mN / m or more, the area around the nozzle of the inkjet head will not be wet and the discharge capacity will not be reduced, and if less than 35 mN / m, the surface energy will be It is preferable because it does not wet well on coated paper and resin recording media, which are lower than ordinary paper, and whitening does not occur. The surface tension of the photocurable inkjet ink can be determined by the Wilhelmy method (plate method). The surface tension of the photocurable inkjet ink can be adjusted by the selection of the photocurable compound described above, the adjustment of the blending ratio, and the addition of the surfactant described above.

  The physical properties of the photocurable inkjet ink of the present invention preferably have physical property values similar to those of a normal photocurable inkjet ink. That is, the viscosity is 2 mPa · s or more and 50 mPa · s or less at 25 ° C., and the ink temperature at ejection is in the range of 20 ° C. or more and less than 100 ° C., preferably 25 ° C. or more and 60 ° C. or less It is preferable to perform ejection at an ink temperature such that the ink viscosity is 7 mPa · s to 15 mPa · s, more preferably 8 mPa · s to 13 mPa · s. The viscosity of the inkjet ink can be determined by a rotational viscometer. In addition, the viscosity of the inkjet ink can be adjusted by the selection of the photopolymerizable compound described above and the adjustment of the blending ratio.

When a pigment is used as a coloring material, there is no gel-like substance having an average particle size exceeding 1.0 μm other than pigment particles, and the conductivity is a conductivity of 10 μS / cm or less, It is preferable to use an ink that does not cause such corrosion. In the continuous type, it is necessary to adjust the conductivity by the electrolyte, and in this case, the conductivity may need to be adjusted to 0.5 mS / cm or more. The conductivity of the inkjet ink can be determined by immersing two electrodes separated by a fixed distance in the ink, applying a fixed voltage between the electrodes, and measuring the value of the current flowing between the electrodes. The conductivity of the ink-jet ink can be adjusted by the selection and blending ratio of the above-mentioned photopolymerizable compound, polymerization initiator, sensitizer and water content of the ink-jet ink.

  In addition, as a physical property of the inkjet ink of the present invention, a further preferable embodiment is a unit when DSC (differential scanning calorific value) measurement of the ink is performed in the range of 25 ° C. to −25 ° C. at a falling rate of 5 ° C. per minute. The calorific value per mass does not show an exothermic peak of 10 mJ / mg or more. By selecting the material according to the configuration of the present invention, it is possible to suppress heat generation of a certain amount or more in DSC measurement. With such a configuration, it is possible to suppress the generation of gel and the generation of precipitates even when the ink is stored at a low temperature.

  Although an inkjet ink containing a photocurable composition as a photocurable composition will be described in detail below as a specific example, it goes without saying that the scope of the present invention is not limited to the inkjet ink.

[Method of preparing photocurable inkjet ink]
The photocurable inkjet ink comprises a photopolymerizable compound which is a photocurable composition, a photoinitiator, a pigment dispersant when a pigment is used as a coloring material, and a pigment, and a common dispersing machine such as a sand mill. It is preferable that it manufactures by disperse | distributing using well. It is preferable to prepare a concentrate having a high concentration of pigment in advance and dilute it with a photopolymerizable compound. Sufficient dispersion is possible even in the case of dispersion with a conventional disperser, and therefore, since excessive dispersion energy is not required and a large dispersion time is not required, it is difficult to cause deterioration at the time of dispersion of ink components, and stability Can be prepared. The prepared ink is preferably filtered with a filter having a pore size of 3 μm or less, and further 1 μm or less.

[recoding media]
As a recording medium used for the recording method using the photocurable composition of the present invention and the recording method using the photocurable ink jet ink, a wide variety of synthetic resins conventionally used in various applications are targeted. Specifically, for example, polyester, polyvinyl chloride, polyethylene, polyurethane, polypropylene, acrylic resin, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, polybutadiene terephthalate and the like can be mentioned, and these synthetic resins The thickness and shape of the substrate are not limited at all. In particular, as a recording medium for the photocurable inkjet ink of the present invention, polypropylene, polyethylene and polyethylene terephthalate are preferable. In addition to this, metals, glass, papers and the like (for example, printing paper) can also be used.

Specific examples of polyvinyl chloride, which is one of the recording media used in the ink jet recording method of the present invention, include SOL-371G, SOL-373M, SOL-4701 (all manufactured by Big Technos Co., Ltd.), glossy polyvinyl chloride (Co., Ltd.) Systemgraphy Co., Ltd., KSM-VS, KSM-VST, KSM-VT (above, Kimoto Co., Ltd.), J-CAL-HGX, J-CAL-YHG, J-CAL-WWPG (above, Co. Made in Osaka, BUS MARK V400 F vinyl, LITEcal V-600 F vinyl (above, made by Flexcon), FR2 (made by Hanwha) LLBAU 13713, LLSP20133 (above, made by Sakurai Co., Ltd.), P-370B, P-400M (above , Kanbo Plus Inc.), S02P, S12P, S 3P, S14P, S22P, S24P, S34P, S27P (above, made by Grafityp), P-223RW, P-224RW, P-249ZW, P-284ZC (above, made by Lintec Corporation), LKG-19, LPA-70 , LPE-248, LPM-45, LTG-11, LTG-21 (all, manufactured by Shinsei Co., Ltd.), MPI 3023 (manufactured by Toyo Corporation), Napoleon Gloss Glossy PVC (manufactured by Nishiki Electronics Co., Ltd.), JV-610, Y-114 (above, made by ICK Corporation), NIJ-CAPVC, NIJ-SPVCGT (above, made by Nichie Co., Ltd.), 3101 / H12 / P4, 3104 / H12 / P4, 3104 / H12 / P4S , 9800 / H12 / P4, 3100 / H12 / R2, 310 / H12 / R2, 3104 / H12 / R2, 1445 / H14 / P3, 1438 / One Way Vision (above, made by Inetrcoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829R, JT5829PM, JT5829RM, JT5929PM (all, Mactac, Inc.) Products), MPI 1005, MPI 1900, MPI 2000, MPI 2001, MPI 2002, MPI 3000, MPI 3021, MPI 350, MPI 3501 (above, made by Avery), AM-101G, AM-501G (above, made by Gin-I Co., Ltd.), FR2 (Hanfa Japan) AY-15P, AY-60P, AY-80P, DBSP 137 GGH, DBSP 137 GGL (all manufactured by Insa Co., Ltd.) SJT-V200F, SJT-V400F-1 (above, manufactured by Hiraoka Textile Co., Ltd.), SPS-98, SPSM-98, SPSH-98, SVGL-137, SVGS-137, MD3-200, MD3 -301M, MD5-100, MD5-101M, MD5-105 (above, manufactured by Metamark), 640M, 641G, 641M, 3105M, 3105SG, 3162G, 3164G, 3164M, 3164XG, 3164XM, 3165G, 3165M, 3169M, 3169M, 3169M, 3169M 3451 SG, 3551 G, 3551 M, 3631, 3641 M, 3651 G, 3651 M, 3651 SG
3951 G, 3641 M (all, manufactured by Orafol), SVTL-HQ130 (manufactured by Lamy Corporation), SP300 GWF, SPCLEARAD vinyl (manufactured by Catalina, Inc.), RM-SJR (manufactured by Ryoyo Trading Co., Ltd.), Hi Lucky, New Lucky PVC (all manufactured by LG), SIY-110, SIY-310, SIY-320 (all manufactured by Sekisui Chemical Co., Ltd.), PRINT MI Frontlit, PRINT XL Light weight banner (all manufactured by Endutex), RIJET 100, RIJET 145, RIJET 165 (all manufactured by Ritrama), NM-SG, NM-SM (manufactured by Nikkei Kako Co., Ltd.), LTO3GS (manufactured by Rukio Co., Ltd.), easy print 80, Performance print 80 (above, made by Jetgraph Co., Ltd.), DSE 550, DSB 550, DSE 800G, DSE 802/137, V250WG, V300WG, V350WG (above, made by Hexis), Digital White 6005PE, 6010PE (above, made by Multifix) Etc.).

  In addition, as a recording medium having a plasticizer-free resin base material or a non-absorbing inorganic base material as a component, the following various base materials may be used alone or in combination of one or more kinds of base materials. Can be used in combination. Examples of the resin-free resin base material used in the present invention include ABS resin, polycarbonate (PC) resin, polyacetal (POM) resin, polyamide (PA) resin, polyethylene terephthalate (PET) resin, polyimide (PI) Examples thereof include resins, acrylic resins, polyethylene (PE) resins, polypropylene (PP) resins, and rigid polyvinyl chloride (PVC) resins containing no plasticizer.

  These resins are characterized by containing no plasticizer, but there are no particular restrictions on other properties such as thickness, shape, color, softening temperature, hardness and the like.

  The recording medium used in the present invention is preferably ABS resin, PET resin, PC resin, POM resin, PA resin, PI resin, rigid PVC resin containing no plasticizer, acrylic resin, PE resin, PP resin. More preferably, they are ABS resin, PET resin, PC resin, PA resin, rigid PVC resin which does not contain a plasticizer, and acrylic resin.

  Moreover, as a non-absorbing inorganic base material used for this invention, a glass plate, metal plates, such as iron and aluminum, a ceramic plate etc. are mentioned, for example. These inorganic substrates are characterized by having no ink absorbing layer on the surface. These non-absorbing inorganic substrates are not particularly limited in various characteristics such as thickness, shape, color, softening temperature, hardness and the like.

  The photocurable inkjet ink of the present invention can particularly well exhibit the effects of the present invention in a recording medium having a surface energy of 25 mN / m or more and less than 50 mN / m. Examples of the surface energy of the recording medium include, for example, IJ 180 CV 2 (manufactured by 3M, polyvinyl chloride, surface energy = 38.0 mN / m), MD 5 (manufactured by Metamark, polyvinyl chloride, surface energy = 36.6 mN / m) ), ORAJET (manufactured by ORACAL, polyvinyl chloride, surface energy = 33.1 mN / m), OPAQUE MATT FILM (manufactured by Oce, polyethylene terephthalate, surface energy = 35.4 mN / m), Tokishi Art (Mitsubishi Paper Industries, Ltd.) Product, art paper, surface energy = 37.6 mN / m), HANITA (manufactured by Hanita Coatings, polyethylene terephthalate, surface energy = 35.4 mN / m), Lumirror 38-T60 (manufactured by Toray Industries, untreated polyethylene terephthalate, surface) Energy = 36.9 m N / m), Sanroid Uni G400 (manufactured by Sumitomo Bakelite, polyvinyl chloride, surface energy = 34.5 mN / m), Sumipex 068 (manufactured by Sumitomo Chemical, acrylic cast, surface energy = 39.5 mN / m), Sanroid Pet Ace EPG 400 (Sumitomo Bakelite Co., Ltd., non-crystalline polyethylene terephthalate, surface energy = 35.7 mN / m), Lintec Gloss (cast coated paper, surface energy 27 mN / m), Maruw Adhesive Co., Ltd. white PET # 50 solvent strength Viscosity PGS (polyethylene terephthalate, surface energy 50 mN / m) etc. can be mentioned.

  The surface energy of the recording medium according to the present invention can be calculated by measuring the contact angle using two or more kinds of liquids whose surface tensions are known.

[Recording method using a photocurable composition]
As a recording method using the photocurable composition, after the photocurable composition is applied, the curable composition is cured by irradiation with ultraviolet light and the like. Coating methods generally used include bar coating, spray coating, curtain coating, roll coating, screen printing, offset printing, and gravure printing. Although the formation of a primer layer, the formation of an image, and the formation of an overcoat layer can be performed by the method described above, particularly, in the case of forming an image using a photocurable composition, screen printing, offset printing, It is preferable to use gravure printing or a bar coat.

[Recording method using a photocurable inkjet ink]
As a recording method using a photocurable inkjet ink, for example, the photocurable inkjet ink is discharged from the inkjet nozzle onto the recording medium, and then the coating film on the recording medium is irradiated with an active energy ray such as ultraviolet light to be an ink And a recording method of curing the resin. The inkjet head used in the recording method for discharging the photocurable inkjet ink to form an image may be an on-demand method or a continuous method. Further, as a discharge method, an electro-mechanical conversion method (for example, single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any discharge method such as a mold, bubble jet (registered trademark) mold, etc. may be used. In addition, the recording method using a photocurable inkjet ink can be suitably used also when forming overcoat layer and a primer layer not only for an image formation use.

[Conditions of active energy ray irradiation after ink landing]
In the ink jet recording method of the present invention, as the irradiation condition of the active energy ray, it is preferable that the active energy ray is irradiated during 0.001 seconds or more and 1.0 seconds or less after ink landing, and more preferably 0.001. Seconds or more and 0.5 seconds or less. In order to form a high definition image, it is preferable that the irradiation timing be as early as possible.

  The irradiation method of the active energy ray is not particularly limited, and can be performed, for example, by the following method.

  A light source is provided on both sides of the head unit described in Japanese Patent Application Laid-Open No. 60-132767, the head and the light source are scanned by a shuttle method, and irradiation is performed with a certain time after ink landing, and further driving is accompanied. Method using a separate light source to complete curing, or the method using an optical fiber described in US Pat. No. 6,145,979, or a collimated light source is applied to the mirror surface provided on the side of the head unit The method of irradiating an ultraviolet-ray can be mentioned.

  Any of these irradiation methods can be used in the ink jet recording method of the present invention.

  In addition, the irradiation of the active energy ray is divided into two steps, first the active energy ray is irradiated by the above-mentioned method within 0.001 seconds to 2.0 seconds after the ink deposition, and further activation is performed after all printing is completed. A method of irradiating energy rays is also one of the preferred embodiments.

  By dividing the irradiation of the active energy ray into two steps, it is more effective in suppressing the shrinkage of the recording material which occurs when the ink is cured.

[Total ink film thickness after ink deposition]
In the ink jet recording method of the present invention, curling of the recording medium, wrinkles, recording that the total ink film thickness after the ink lands on the recording medium and is cured by irradiation with active energy rays is 2 μm or more and 20 μm or less It is preferable from the viewpoint of suppressing the inconvenience to the appearance and the texture such as the change of the texture of the medium.

  The term “total ink film thickness” as used herein means the maximum value of the film thickness of the ink drawn on the recording medium, and it is a single color, other two color overlapping (secondary color), three color overlapping, Even when recording is performed by an inkjet recording method of four-color overlapping (white ink base), the meaning of the total ink film thickness is the same.

[Ink heating and discharge conditions]
In the ink jet recording method of the present invention, it is preferable from the viewpoint of ejection stability that the active energy ray be irradiated while the active energy ray curable ink jet ink is heated.

  The heating temperature is preferably 35 ° C. to 100 ° C., more preferably 35 ° C. to 80 ° C., from the viewpoint of discharge stability by irradiating the active energy ray.

  There is no particular limitation on the method of heating and keeping the ink-jet ink at a predetermined temperature, but there is no particular limitation, for example, an ink tank constituting the head carriage, a supply pipe, an ink supply system such as a front chamber ink tank just before the head, piping with a filter, There is a method in which the piezoelectric head or the like is thermally insulated and heated to a predetermined temperature by a panel heater, a ribbon heater, heat retaining water or the like.

  The control range of the ink temperature is preferably a set temperature ± 5 ° C., more preferably a set temperature ± 2 ° C., and particularly preferably a set temperature ± 1 ° C. from the viewpoint of discharge stability.

  The amount of droplets discharged from each nozzle is preferably 2 pL or more and 20 pL or less from the viewpoint of recording speed and image quality.

[Ink jet recording apparatus]
Next, an inkjet recording apparatus (hereinafter, simply referred to as a recording apparatus) that can be used for the inkjet recording method of the present invention will be described.

  Hereinafter, the recording apparatus will be described with reference to the drawings as appropriate.

FIG. 1 is a front view showing the configuration of the main part of the recording apparatus.
The recording apparatus 1 includes a head carriage 2, a recording head 3, an irradiation unit 4, a platen unit 5 and the like.

  The platen unit 5 is disposed below the recording medium P. The platen unit (recording medium support member) 5 has a function of absorbing ultraviolet light, and absorbs excess ultraviolet light that has passed through the recording medium P. As a result, high-definition images can be reproduced very stably.

  The recording medium P is guided by the guide member 6 and moves in the direction from the front to the back in FIG. 1 by the operation of the conveyance means (not shown). Head scanning means (not shown) performs scanning of the recording head 3 held by the head carriage 2 by reciprocating the head carriage 2 in the Y direction in FIG.

  The head carriage 2 is disposed on the upper side of the recording medium P, and stores a plurality of recording heads 3 described later according to the number of colors used for printing an image on the recording medium P, and arranges the discharge ports on the lower side.

  The head carriage 2 is installed on the main body of the recording apparatus 1 so as to reciprocate in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by the drive of the head scanning means.

  In FIG. 1, the head carriage 2 is white (W), yellow (Y), magenta (M), cyan (C), black (K), light yellow (Ly), light magenta (Lm), light cyan (Lc) The drawing is performed to store the recording heads 3 of light black (Lk) and white (W), but the color number of the recording heads 3 stored in the head carriage 2 can be appropriately determined in practice. It is a thing.

  The recording head 3 is directed from the discharge port toward the recording medium P by the operation of discharge means (not shown) provided with a plurality of photo curable inkjet inks supplied by the ink supply means (not shown). Discharge.

  During the scanning that the recording head 3 moves from the one end of the recording medium P to the other end of the recording medium P in the Y direction in FIG. 1 by the drive of the head scanning means, a certain area (landable area) on the recording medium P On the other hand, the photocurable inkjet ink is discharged as an ink droplet, and the ink droplet is landed on the possible landing area.

  After the above-described scanning is performed as many times as necessary and the photocurable inkjet ink is discharged toward the landable area of one area, the recording medium P is appropriately moved from the front side to the rear side in FIG. While the scanning by means is performed, the recording head 3 discharges the photocurable inkjet ink to the next possible landing area adjacent in the back direction in FIG. 1 with respect to the possible landing area.

  The above-described operation is repeated, and the recording head 3 discharges the photocurable inkjet ink etc. in conjunction with the head scanning means and the transport means, whereby an image consisting of an aggregate of photocurable inkjet ink droplets is formed on the recording medium P. It is formed.

  The irradiation unit 4 is configured to include a light source 8, for example, an ultraviolet lamp that emits ultraviolet light of a specific wavelength range with stable exposure energy, and a filter that transmits ultraviolet light of a specific wavelength.

  Here, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a black light, an LED (light emitting diode), etc. are applicable as the ultraviolet lamp. A cathode tube, a hot cathode tube, a mercury lamp or a black light is preferable, and in particular, an LED is preferable because of its long life and low cost.

  By using the LED as the radiation source of the irradiation means 4, the irradiation means 4 for curing the ultraviolet ink can be manufactured inexpensively.

  However, in general, the LED is a single wavelength light source, and the illuminance tends to be lower than a light source having a plurality of emission line spectra such as a high pressure mercury lamp. For example, in the case of curing by radical polymerization, if the illuminance is low, the rate at which radicals bond with oxygen and inactivate increases, so curing becomes difficult even if the time is the same and the integrated light quantity is the same. Therefore, it is required that the ink be curable with a low illuminance and a low integration amount.

  In order to use an inexpensive LED light source, the illuminance is preferably 8 W / cm 2 or less, more preferably 2 W / cm 2 or less.

  The irradiation unit 4 is the largest of the possible landing areas in which the recording head 3 discharges the photocurable inkjet ink by one scan by the drive of the head scanning unit, which can be set by the recording apparatus (photocurable inkjet inkjet printer) 1 The shape is substantially the same as that of the above, or the shape larger than the possible landing area.

The irradiation means 4 is fixedly installed on both sides of the head carriage 2 substantially in parallel to the recording medium P.

  As described above, as a means for adjusting the illuminance of the ink discharge section, it is a matter of course that the entire recording head 3 is shielded from light, but additionally, from the distance h1 of the irradiating means 4 and the recording medium P, the ink discharge of the recording head 3 It is effective to increase the distance h2 between the section 31 and the recording medium P (h1 <h2) or to separate the distance between the recording head 3 and the irradiating means 4 (to increase the distance).

Further, as shown in FIG. 1, it is preferable to form a bellows structure 7 between the recording head 3 and the irradiating means 4.

Here, the wavelength of the ultraviolet light irradiated by the irradiation unit 4 can be appropriately changed by replacing the ultraviolet lamp or the filter provided in the irradiation unit 4.

  FIG. 2 is a top view showing another example of the configuration of the main part of the ink jet recording apparatus.

The ink jet recording apparatus shown in FIG. 2 is called a line head system, and a plurality of ink jet recording heads 3 of each color are fixedly disposed on the head carriage 2 so as to cover the entire width of the recording medium P. ing.

On the other hand, on the downstream side of the head carriage 2 in the recording medium conveyance direction, that is, at the rear of the head carriage 2 with respect to the recording medium P to be conveyed, the entire width of the recording medium P is covered as well. There are provided irradiation means 4 arranged to cover.

  The ultraviolet lamp used for the irradiation means 4 can be the same as that described in FIG.

In this line head method, the head carriage 2 and the irradiation unit 4 are fixed, and only the recording medium P is conveyed to perform ink ejection and curing to form an image.

Although the recording method in the case of using as an inkjet ink has been described in detail, for example, a layer made of a photocurable composition, such as a primer layer or an overcoat layer, can be formed on a recording medium using an inkjet recording device. For example, in the case of forming a transparent primer layer, a photocurable composition containing no coloring material such as a pigment is discharged from an ink jet head, and the discharged photocurable composition is cured by irradiation with ultraviolet light or the like. It can be formed. Further, after forming the primer layer described above, an image is formed by discharging an ink-jet ink containing a coloring material such as a pigment, whereby a high-quality image can be formed even on a non-absorbing medium, for example. It is possible to form an image with high adhesion while suppressing curing shrinkage.
Also, after forming an image, also when forming a transparent overcoat layer, the photocurable composition containing no coloring material such as a pigment is discharged from the ink jet head, and the discharged photocurable composition is irradiated with ultraviolet light or the like. It is formed by irradiating and curing. In this case, an overcoat layer can be provided that adheres well to the formed image and can suppress curing shrinkage.
The photocurable composition may contain a coloring material such as a pigment to form a colored primer layer or overcoat layer.

<< Preparation of a photocurable composition >>
Samples (photocurable compositions) 1 to 14 were prepared according to the compositions described in Table 1 in order to form a primer layer on a recording medium. Preparation of a photocurable composition removed methyl ethyl ketone by pressure-removing the photocurable resin (A)-(G) diluted with methyl ethyl ketone, and adjusted the concentrate. An intramolecular cleavage initiator, a hydrogen abstraction initiator, an acrylic copolymer resin and the like were contained in the concentrate of the photocurable resins (A) to (G) described above according to the composition of Table 1. Next, it diluted with photopolymerizable compounds (A)-(C), and adjusted by stirring.
[Photopolymerizable Compound (A)]
1,6-Hexanediol diacrylate: Molecular weight 226 (V # 230, manufactured by Osaka Organic Chemical Company)
[Photopolymerizable Compound (B)]
Diethylene glycol diacrylate: Molecular weight 214 (SR 230, manufactured by Sartmar)
[Photopolymerizable Compound (C)]
Benzyl acrylate: Molecular weight 162 (V # 160, manufactured by Osaka Organic Chemical Company)
[Photo-curable resin (A)]
Polymer type acrylate resin: Molecular weight 60000 (Hitaloid 7988, manufactured by Hitachi Chemical Co., Ltd.)
[Photo-curable resin (B)]
Polymer type acrylate resin: Molecular weight 42000 (8KX-078, manufactured by Taisei Fine Chemical Co., Ltd.)
[Photo-curable resin (C)]
Polymer type acrylate resin: Molecular weight 25000 (8KX-012C, manufactured by Taisei Fine Chemical Co., Ltd.)
[Photo-curable resin (D)]
Polymer type acrylate resin: Molecular weight 47000 (8KX-052C, manufactured by Taisei Fine Chemical Co., Ltd.)
[Photo-curable resin (E)]
Polymer type acrylate resin: Molecular weight 78000 (Hitaloid 7975, manufactured by Hitachi Chemical Co., Ltd.)
[Photo-curable resin (F)]
Polymer type acrylate resin: Molecular weight 47000 (8KX-056, manufactured by Taisei Fine Chemical Co., Ltd.)
[Photo-curable resin (G)]
Polymer type acrylate resin: Molecular weight 180000 (8 BR-500, manufactured by Taisei Fine Chemical Co., Ltd.)
[Oligomer]
Dendric Acrylate: Molecular Weight 2000 (SP1010, Miwon)
[Acrylic copolymer resin]
Polymethyl methacrylate: Molecular weight 30000 (PMMA, manufactured by Tokyo Chemical Industry Co., Ltd.)
It was incorporated as a resin having no photopolymerizable group.
[Intramolecular cleavage initiator]
DAROCURE TPO (made by Ciba)
[Hydrogen abstraction initiator]
SPEEDCURE ITX (made by DKSH)

<< Method for forming coating film of photocurable composition >>
In the present example, a coating of the photocurable composition was formed by a bar coating method. Each sample 1 to 14 prepared above was coated on a bar coater with a white PET # 50 (made by Maru Glue Co., Ltd.) 75 mm wide and 130 mm long, a corona-treated biaxially stretched polypropylene film OPP (made by Okamoto Co., Ltd.), and Yupo (Yupo) Uniformly applied to a thickness of 10 .mu.m. After application, it was cured with a Phoseon Technology LED lamp (8 W / cm ² , water cooled unit).

Evaluation of adhesion to recording material
In the image solid print part, a pressure sensitive adhesive tape (Scotch # 250, made by Sumitomo 3M) is bonded to the cured composition sample obtained by the cross-cut tape peeling and residual adhesion test (the cross-cut test according to JIS K 5400) and reciprocated by a 2 kg roller After pressure bonding, it was peeled off at once, the number of remaining grid-like samples was examined, the adhesion rate was evaluated by the following rank, and it was used as one of the indexes of adhesion. More than Δ is a practically good range.

○: adhesion residual rate 80% or more 100%
Δ: Adhesion residual rate 60% or more and less than 80% ×: Adhesion residual rate less than 60%

<< Curl evaluation >>
About each hardened | cured material of the samples 1-14 recorded by the said coating-film formation method, the generation | occurrence | production degree of the curl by hardening shrinkage was observed visually, and the following reference | standard evaluated.

○: no warping in the cured product Δ: warping in the cured product is observed, but within the allowable range ×: large warping in the cured product, NG level «Curable evaluation (pencil hardness)»
After leaving a solid image output product to stand in an environment of 25 ° C. and 60% RH for 24 hours, the pencil hardness of the surface was measured according to JIS-K-5400 and evaluated according to the following rank, and it was regarded as one of the indicators of curability. .

○: Pencil hardness 2H or more △: B, F, H
X: The results obtained below 2 B are shown in Table 1 as follows.

  As shown in Table 1, the sample which is an example of the present invention gave a good evaluation in any evaluation item.

Next, an example in which a pigment is contained as a coloring material in the photocurable composition of the present invention and used as an inkjet ink will be shown below.
<< Preparation of pigment dispersion liquid >>
The pigment was dispersed according to the following composition.

  The following two compounds were placed in a stainless beaker and dissolved by heating and stirring for 1 hour while heating on a hot plate at 65 ° C.

Hydrazine PB 824 9 parts Diethylene glycol diacrylate (SR 230, manufactured by Sartmar Co., Ltd.) 71 parts After cooling to room temperature, add 20 parts of the following pigment to this and put it in a glass bottle with 200 g of zirconia beads of 0.5 mm in diameter After dispersing for 5 hours, the zirconia beads were removed.

Pigment Dispersion 1: Pigment Black 7 (Mitsubishi Chemical Corporation # 52)
<< Preparation of inkjet ink >>
Samples (inkjet inks) 15 to 19 of the ink compositions described in Table 2 were prepared, and filtration was performed using a Teflon (registered trademark) 3 μm membrane filter manufactured by ADVATEC. In addition, as a photopolymerizable compound in Table 2, the following were used.
Similarly, the photocurable resin (C) diluted in methyl ethyl ketone organic solvent is removed by distillation under reduced pressure to remove the methyl ethyl ketone organic solvent to obtain a high concentration solution, and then an acrylic copolymer resin, an intramolecular cleavage initiator, hydrogen A withdrawal initiator was included according to Table 2. Next, the pigment was dispersed by adding a highly concentrated solution in which the pigment is concentrated, and well dispersing using a conventional dispersing machine such as a sand mill. Thereafter, the ink composition was prepared by diluting with the photopolymerizable compounds (A) to (C) and thoroughly stirring.
[Photopolymerizable Compound (A)]
1,6-Hexanediol diacrylate: Molecular weight 226 (V # 230, manufactured by Osaka Organic Chemical Company)
[Photopolymerizable Compound (B)]
Diethylene glycol diacrylate: Molecular weight 214 (SR 230, manufactured by Sartmar)
[Photopolymerizable Compound (C)]
Benzyl acrylate: molecular weight 128.2 (V # 160, manufactured by Osaka Organic Chemical Company)
[Photo-curable resin (C)]
Polymer type acrylate resin: Molecular weight 25,000 (8KX-012C, manufactured by Taisei Fine Chemical Co., Ltd.)
[Intramolecular cleavage initiator]
DAROCURE TPO (made by Ciba)
[Hydrogen abstraction initiator]
SPEEDCURE ITX (made by DKSH)
[Surfactant]
KF-352 (Shin-Etsu Chemical Co., Ltd.)

<< Ink jet image formation method >>
Each of the prepared samples 15 to 19 was loaded into an ink jet recording apparatus having an ink jet recording head provided with a piezo type ink jet nozzle, and a long white PET # 50 (manufactured by Maru Glue Co., Ltd.) having a width of 600 mm and a length of 500 m. Image recording was continuously performed on a corona-treated biaxially oriented polypropylene film OPP (manufactured by Okamoto Co., Ltd.), Yupo, below. The conveyance speed of the recording material was 30 m / s.

  Although not shown, the ink supply system includes an ink tank, a supply pipe, a sub-ink tank immediately in front of the head, a pipe with a filter, and a piezo head. The piezo head applied a voltage so as to form 2 pl droplets and was ejected using four 360 dpi resolution heads for each color to form a K solid color solid image of 1440 × 1440 dpi.

After printing, it was cured using an LED lamp (8 W / cm ² , water cooled unit) manufactured by Phoseon Technology. Irradiation was performed at a distance of 5 mm from the tube surface (irradiation width of 20 mm in the transport direction).

Evaluation of adhesion to recording material
In the image solid print part, a pressure sensitive adhesive tape (Scotch # 250, made by Sumitomo 3M) is bonded to the cured composition sample obtained by the cross-cut tape peeling and residual adhesion test (the cross-cut test according to JIS K 5400) and reciprocated by a 2 kg roller After pressure bonding, it was peeled off at once, the number of remaining grid-like samples was examined, the adhesion rate was evaluated by the following rank, and it was used as one of the indexes of adhesion. More than Δ is a practically good range.

○: adhesion residual rate 80% or more 100%
Δ: Adhesion residual rate 60% or more and less than 80% ×: Adhesion residual rate less than 60%

<< Curl evaluation >>
About each image of the samples 15-19 recorded by the said image formation method, the generation | occurrence | production degree of the curl by hardening shrinkage was observed visually, and the following reference | standard evaluated.

:: no warping in the cured product :: warping is observed in the cured product, but within the allowable range ×: large warping in the cured product, NG level

"Hardness evaluation (pencil hardness)"
After leaving a solid image output product to stand in an environment of 25 ° C. and 60% RH for 24 hours, the pencil hardness of the surface was measured according to JIS-K-5400 and evaluated according to the following rank, and it was regarded as one of the indicators of curability. .

○: Pencil hardness 2H or more △: B, F, H
×: 2 B or less Table 2 summarizes the obtained results. The sample which is an Example of this invention obtained favorable evaluation also in any evaluation item.

  The photocurable composition of the present invention and the photocurable inkjet ink containing the photocurable composition are suitable for forming an image on a recording medium, particularly a non-absorbing recording medium.

DESCRIPTION OF SYMBOLS 1 recording device 2 head carriage 3 recording head 4 irradiation means 5 platen part 6 guide member 7 bellows structure 8 light source 31 ink discharge part

Claims (11)

A photopolymerizable monomer and / or a photopolymerizable oligomer,
With a photoinitiator
Photocurable resin having a photopolymerizable group in a side chain and having a weight average molecular weight of 10000 or more and 70000 or less (but excluding a copolymer formed from a monomer component containing 5 mol% or more of N-vinylamide) A photocurable inkjet ink containing
The content of the photopolymerizable monomer and / or the photopolymerizable oligomer is 60% by mass or more and 90% by mass or less based on the total mass of the photocurable inkjet ink,
The content of the photo-curing resin, relative to the total weight of the photocurable inkjet ink state, and are 5 wt% to 30 wt% or less,
The photocurable resin, light-curable inkjet ink, wherein polymeric acrylate der Rukoto.   The photocurable inkjet ink according to claim 1, wherein the equivalent of the photopolymerizable group of the photocurable resin is 100 or more and 1000 or less.   The photocurable inkjet ink according to claim 1 or 2, wherein an equivalent weight of the photopolymerizable group of the photocurable resin is 100 or more and 500 or less. The photocurable inkjet ink according to any one of claims 1 to 3 , wherein the photocurable resin is a polymer type acrylate having a (meth) acrylic group in a side chain. The organic solvent of 5 mass% or less is contained with respect to the total mass of the said photocurable inkjet ink, The photocurable inkjet ink of any one of the Claims 1 thru | or 4 characterized by the above-mentioned. The photocurable inkjet ink according to any one of claims 1 to 5 , further comprising a coloring material. The photocurable inkjet ink according to claim 6 , wherein the colorant is a pigment and further contains a pigment dispersant. The content of the pigment is 1.5% by mass to 8% by mass with respect to the total mass of the photocurable inkjet ink when the photocurable inkjet ink is an ink other than white, and the photocurable 8. The photocurable inkjet ink according to claim 7 , which is 10% by mass or more and 30% by mass or less based on the total mass of the photocurable inkjet ink in the case where the organic inkjet ink is a white ink containing titanium oxide. An image forming method comprising: applying a photocurable inkjet ink according to any one of claims 1 to 8 to a recording medium, and then irradiating an active ray to cure the photocurable inkjet ink. The image forming method according to claim 9 , wherein the recording medium is at least one selected from the group consisting of polypropylene, polyethylene and polyethylene terephthalate. The illuminance of the irradiated are active ray is 8W / cm ² or less, the image forming method according to claim 9 or 10.

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