JP6170210B2 - Energy ray curable primer ink - Google Patents

Description

  The present invention relates to an energy ray curable primer ink.

  An ink jet recording method in which ink is ejected as droplets from an ink ejection port is used in many printers because it is small and inexpensive, and can form an image without contact with a recording medium.

  Recently, commercial printing and industrial printing using an ink jet printer have been performed not only for photographic printing and document printing for home or office, but also for advertising, posters, and decoration. Along with this, inkjet ink and inkjet recording printed matter for home or office use (1) high quality of the formed image, and (2) any recording medium including non-permeable recording media such as plastic. There is a strong demand for printability.

  2. Description of the Related Art Home or office ink jet ink, ink jet recording apparatus, and ink jet recording method (hereinafter collectively referred to as “ink jet ink etc.”) have been developed with the intention of photographic printing or document printing. In many cases, when recording on a non-permeable recording medium, with conventional ink-jet inks, if it takes time to dry the droplets after droplet ejection or penetrate into the recording medium, the image will bleed. In addition, there is a problem that mixing occurs between adjacent ink droplets on the recording medium, which hinders sharp image formation. Further, the most important practical problem of an image recorded on a non-permeable recording medium is that the fixing property of the image is not good, such as being easily peeled off from the recording medium and being inferior in scratching. .

  In addition, as a problem in the case of adapting to high-speed printing, generation of color unevenness due to droplet ejection interference can be cited. Interference with droplet ejection means that adjacent droplets that have been ejected coalesce and movement of the droplets occurs, so that it shifts from the landing position, and when drawing a thin line, the line width is uneven and coloring occurs. This refers to a phenomenon in which color unevenness occurs when a surface is drawn. Hereinafter, in this specification, characteristics such as scratchability and ease of peeling are referred to as “fixability”, and characteristics relating to image quality such as color unevenness and non-uniform line width are referred to as “drawability”.

  For the purpose of improving image fixability and drawing performance, various techniques have been proposed for inkjet inks and the like as methods for solving the above problems. Examples thereof are broadly classified into a technique for improving the components and configuration of the ink itself (for example, Patent Document 1) and a technique for improving the ink jet recording apparatus and the ink jet recording method (for example, Patent Document 2). In particular, as a printed matter for commercial use or industrial use, fixability of an image recorded on a non-permeable recording medium is important, and cannot be solved by the technique disclosed in such literature. Therefore, Patent Document 3 discloses an ink jet recording method in which a primer ink is employed for the problem of image fixability, and the primer ink is semi-cured and performed in a single pass. It also suggests and describes the components of inkjet ink and primer ink, their preferred physical properties, and the relationship between them. Japanese Patent Application Laid-Open No. 2004-133867 attempts to solve the problem of image fixability from a comprehensive viewpoint.

Special table 2003-53223 gazette Japanese Patent Laying-Open No. 2005-096254 JP 2009-083267 A

  However, a primer ink is formed using the compound described in Patent Document 3, and is an impermeable recording medium other than polyethylene terephthalate (PET), which is not taken up in Patent Document 3, such as olefin-based synthetic paper, The image recorded on the chemical fiber label paper peeled off immediately after being rubbed lightly with a nail, and did not reach the stage of evaluating drawability. That is, the present situation is that sufficient fixing property and high quality drawing property of an image recorded on a non-permeable recording medium have not been obtained yet.

  The present invention has been made to solve the above problems, and provides an energy beam curable primer ink capable of improving the fixability and drawing performance of an image recorded with an inkjet ink on a non-permeable recording medium. To do.

The energy ray curable primer ink of the present invention is a polymerization compound that initiates and accelerates a polymerization reaction or a crosslinking reaction of a polymerizable compound that causes a polymerization reaction or a crosslinking reaction upon irradiation with an energy ray and cures. An energy ray curable primer ink containing an agent,
The polymerizable compound is
Consisting of only a monofunctional monomer, or a monofunctional monomer and a bifunctional monomer, and
A monomer having a (meth) acrylic group and any one functional group of an oxetane group, an oxirane ring and a vinyl ether group in the molecule;
2-hydroxy-3-phenoxypropyl acrylate,
The total of the monomer and the 2-hydroxy-3-phenoxypropyl acrylate is 25 to 95% by mass with respect to the total amount of the ink,
The content of the 2-hydroxy-3-phenoxypropyl acrylate is 10% by mass or more based on the total amount of the ink.

  According to the present invention, it is possible to improve the fixability and the drawability of an image recorded with an inkjet ink on a non-permeable recording medium.

  As a method for solving the fixability of an image recorded with inkjet ink on a non-permeable recording medium, which is the most important problem of the present invention, it is effective to apply a primer ink on the recording medium. Substances used for the primer ink have been proposed in many past documents, but as described above, sufficient image fixing and drawing properties have not been obtained. As the primer ink, functionally, (1) ensuring adhesion with the recording medium, (2) affinity with an image printed (formed) using the image forming ink, (3 ) It is desirable to satisfy all the conditions of coating film curability, and as a result of intensive studies, the present inventors have found an energy ray curable primer ink that satisfies the above conditions. Hereinafter, the energy ray curable primer ink of the present invention and an image forming method using the same will be described.

(Energy ray curable primer ink)
The energy ray curable primer ink of the present invention (hereinafter also simply referred to as primer ink) is a polymerizable compound that cures by causing a polymerization reaction or a crosslinking reaction upon irradiation with energy rays, and a polymerization reaction or crosslinking of the polymerizable compound. And a polymerization initiator that initiates and accelerates the reaction. In addition, as a method for applying the primer ink of the present invention to a recording medium, either ink jet droplet ejection or coating may be used.

<Polymerizable compound>
The polymerizable compound used in the primer ink of the present invention is composed of only a monofunctional monomer, or a monofunctional monomer and a bifunctional monomer, and has a (meth) acryl group, an oxetane group, and an oxirane ring (epoxy group) in the molecule. And a monomer having any one functional group of vinyl ether groups (hereinafter referred to as “monomer a”) and 2-hydroxy-3-phenoxypropyl acrylate (hereinafter referred to as “monomer b”). In the present invention, by using a polymerizable compound composed of only a monofunctional monomer or a monofunctional monomer and a bifunctional monomer, the curing shrinkage of the primer ink after application onto the recording medium is reduced, and the primer ink and the recording medium are recorded. Adhesion with the medium can be improved. Furthermore, when the recording medium is a flexible film, the occurrence of curling (warping) of the recording medium after application of the primer ink can be suppressed, and the reliability can be improved.

  The total of the monomer a and the monomer b is 25 to 95% by mass with respect to the total amount of ink. As a result, the adhesion between the primer ink and the recording medium and the adhesion between the primer ink and the image forming ink can be improved.

  The content of the monomer b is 10% by mass or more with respect to the total amount of the ink. Thereby, the adhesiveness between the primer ink and the recording medium and the adhesiveness between the primer ink and the image forming ink can be further improved.

  Examples of the monomer a include (meth) acrylic groups and oxetane groups such as oxetane acrylate (“OXE-10” manufactured by Osaka Organic Chemical Industry Co., Ltd.) and oxetane methacrylate (“OXE-30” manufactured by Osaka Organic Chemical Industrial Co., Ltd.). (Meth) such as glycidyl acrylate, glycidyl methacrylate, glycidyloxybutyl acrylate, glycidyloxybutyl methacrylate, glycidyloxyethyl acrylate, glycidyloxyethyl methacrylate, glycidyloxypropyl acrylate, glycidyloxypropyl methacrylate Monomers having an acrylic group and an oxirane ring; (meth) acrylic groups such as 2- (2-vinyloxyethoxy) ethyl acrylate and 2- (2-vinyloxyethoxy) ethyl methacrylate and vinyl ether Monomers having an Le group; and the like. Considering supply stability, cost, etc., the monomer a having the (meth) acryl group and vinyl ether group is particularly preferably 2- (2-vinyloxyethoxy) ethyl (meth) acrylate.

  The polymerizable compound used in the primer ink of the present invention can further contain a monomer having only an acrylic group. In this case, it is possible to adjust the viscosity of the primer ink and the glass transition temperature of the cured product contained in the primer ink.

  Examples of the monomer having only the acrylic group include monofunctional (meth) acrylates and bifunctional (meth) acrylates as shown below.

  Specific examples of monofunctional (meth) acrylates include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, isodecyl ( (Meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) Acrylate, 2-ethylhexyl diglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, shear Ethyl (meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl (meth) acrylate, 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, 4 -Butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) Acrylate, tetrahydrofurfuryl (meth) acrylate, hydroxyalkyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (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 Luether (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-methacryloyloxytyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate , Butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooct Ethyl (meth) acrylate, ethylene oxide (EO) modified phenol (meth) acrylate, EO modified cresol (meth) acrylate, EO modified nonylphenol (meth) acrylate, propylene oxide (PO) modified nonylphenol (meth) acrylate, EO modified-2 -Ethylhexyl (meth) acrylate etc. are mentioned.

  Specific examples of the bifunctional (meth) acrylate include 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, hydroxypivalic acid neopentyl glycol di (meth) acrylate, 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-nonane (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, tricyclodecane di (meth) acrylate and the like.

  Examples of energy rays for causing the polymerization reaction or the crosslinking reaction of the polymerizable compound include ultraviolet rays, visible rays, α rays, γ rays, X rays, and electron beams.

<Polymerization initiator>
The polymerization initiator used in the primer ink of the present invention generates an initiation species such as a radical by applying actinic light, heat, or both energies, and initiates and accelerates the polymerization reaction or crosslinking reaction of the polymerizable compound described above. It is particularly preferable that it is a photopolymerization initiator.

  Examples of the photopolymerization initiator include actinic rays to be irradiated, for example, ultraviolet rays of 200 to 400 nm, far ultraviolet rays, g rays, h rays, i rays, KrF excimer laser rays, ArF excimer laser rays, electron rays, X rays, Those having sensitivity to a molecular beam, an LED beam, an ion beam, or the like can be appropriately selected and used.

  Specific photopolymerization initiators known among those skilled in the art can be used without limitation. Preferred photopolymerization initiators include (a) aromatic ketones, (b) aromatic onium salts, (c) organic peroxides, (d) hexaarylbiimidazole compounds, (e) ketoxime ester compounds, f) borate compounds, (g) azinium compounds, (h) metallocene compounds, (i) active ester compounds, (j) compounds having a carbon halogen bond, and the like. Hereinafter, specific examples of each compound will be shown.

  Examples of the aromatic ketones (a) include compounds having a benzophenone skeleton or a thioxanthone skeleton, α-thiobenzophenone compounds, benzoin ether compounds, α-substituted benzoin compounds, benzoin derivatives, aroylphosphonic acid esters, dialkoxybenzophenones Benzoin ethers, α-aminobenzophenones, p-di (dimethylaminobenzoyl) benzene, thio-substituted aromatic ketones, α-aminoalkylphenones, acylphosphine oxides, acylphosphines, thioxanthones, coumarins, and the like. it can.

  As the (b) aromatic onium salt, elements of groups V, VI and VII of the periodic table, specifically, N, P, As, Sb, Bi, O, S, Se, Te, or I Aromatic onium salts are included. Iodonium salts, sulfonium salts, diazonium salts (such as benzenediazonium which may have a substituent), diazonium salt resins (such as formaldehyde resin of diazodiphenylamine), N-alkoxypyridinium salts and the like are preferably used. These salts generate radicals and acids as active species.

  The organic peroxide (c) includes almost all organic compounds having one or more oxygen-oxygen bonds in the molecule.

  Examples of the (d) hexaarylbiimidazole compound include lophine dimers.

  Examples of the (e) ketoxime ester compound include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutane-2-one, and 2-acetoxyimino. Pentan-3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminobutan-2-one, And 2-ethoxycarbonyloxyimino-1-phenylpropan-1-one.

  Examples of the (f) borate compound include U.S. Pat. No. 3,567,453, U.S. Pat. No. 4,343,891, European Patent 109,772, European Patent 109, And the compounds described in the specification of 773.

  Examples of the above (g) azinium compound include JP-A-63-138345, JP-A-63-142345, JP-A-63-142346, JP-A-63-143537, JP-B-46. The compound group which has NO bond described in -42363 gazette can be mentioned.

  Examples of the (h) metallocene compound include titanocene compounds and iron-arene complexes.

  Examples of the (i) active ester compound include nitrobenzester compounds and iminosulfonate compounds.

  Preferred examples of the compound (j) having a carbon halogen bond include those described in Wakabayashi et al., Bull. Chem. Soc. Japan, 42, 2924 (1969), F.I. C. J. Schaefer et al. Org. Chem. 29, 1527 (1964).

  The polymerization initiator used in the primer ink of the present invention is preferably an aromatic ketone among the above-mentioned compounds from the viewpoint of curability, more preferably a compound having a benzophenone skeleton or a thioxanthone skeleton, and an α-aminoalkylphenone. Acylphosphine oxide is particularly preferable.

  The said polymerization initiator can be used individually by 1 type or in combination of 2 or more types. Further, as long as the effects of the present invention are not impaired, a known sensitizer can be used in combination for the purpose of improving the sensitivity of the polymerization initiator. The sensitizer will be described later.

  The content of the polymerization initiator is preferably from 0.1 to 20 mass%, more preferably from 0.5 to 10 mass%, based on the total solid content in the ink. If it is 0.1% by mass or more, sufficient curability can be obtained, and if it is 20% by mass or less, it is possible to prevent problems caused by precipitation / precipitation even when the ink is stored at a low temperature.

  In the primer ink of the present invention, the content ratio (mass ratio) of the polymerization initiator and the polymerizable compound is preferably 0.5: 100 to 30: 100, and is 1: 100 to 15: 100. It is more preferable. If the mass ratio is 0.5: 100 or more, sufficient curability can be obtained, and if it is 30: 100 or less, it is possible to prevent problems caused by precipitation and precipitation even when the ink is stored at a low temperature.

  You may further add substances other than the said polymeric compound and the said polymerization initiator to the primer ink of this invention. Hereinafter, substances that can be added will be described.

  The primer ink of the present invention can further contain at least one resin selected from the group consisting of acrylic resins, polyester resins, polyurethane resins, vinyl chloride resins, and nitrocellulose as an additive resin. In this case, it becomes easy to adjust the viscosity of the primer ink to a desired region.

  Examples of the acrylic resin include “Dianar BR113” manufactured by Mitsubishi Rayon Co., “John Krill” manufactured by Johnson Polymer Co., Ltd., and “ESREC P” manufactured by Sekisui Chemical Co., Ltd. Examples of the polyester resin include “Elitel” manufactured by Unitika, “Byron” manufactured by Toyobo. Examples of the polyurethane resin include “Byron UR” manufactured by Toyobo Co., Ltd., “NT-Hilamic” manufactured by Dainichi Seika Co., Ltd., “Chris Bon” manufactured by Dainippon Ink & Chemicals, “Nipporan” manufactured by Nippon Polyurethane Co., Ltd. Can be mentioned. Examples of the vinyl chloride resin include “SOLBIN” manufactured by Nissin Chemical Industry, “Sekisui PVC-TG”, “Sekisui PVC-HA” manufactured by Sekisui Chemical, and UCAR series manufactured by Dow Chemical. Examples of the nitrocellulose include “HIG”, “LIG”, “SL”, “VX” manufactured by Asahi Kasei Corporation, “RS”, “SS” manufactured by Daicel Chemical Industries, Ltd., and the like.

  The primer ink of the present invention can further contain a surface conditioner for the purpose of improving wettability to a recording medium and preventing repellency. In this case, the surface tension of the primer ink can be adjusted appropriately.

  Specific examples of the surface conditioner include anionic surface conditioners such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, Nonionic surface conditioners such as polyoxyethylene / polyoxypropylene block copolymers, cationic surface conditioners such as alkylamine salts and quaternary ammonium salts, silicon surface conditioners, fluorine surface conditioners, etc. .

  The content of the surface conditioner is appropriately selected depending on the purpose of use, and can be set to 0.0001 to 1% by mass with respect to the total amount of the primer ink, for example. The surface tension of the primer ink is preferably larger than the surface tension of the image forming ink described later, and the amount of the surface conditioner added can be adjusted as necessary within the above range.

  A known sensitizer may be added to the primer ink of the present invention for the purpose of improving the sensitivity of the polymerization initiator. As the sensitizer, for example, it belongs to compounds such as polynuclear aromatics, xanthenes, cyanines, merocyanines, thiazines, acridines, anthraquinones, coumarins, and has an absorption wavelength in the range of 350 nm to 450 nm. A sensitizing dye is mentioned.

  A co-sensitizer, a storage stabilizer, a solvent, and an anti-gelling agent can be added to the primer ink of the present invention depending on the purpose.

  The co-sensitizer can be added for the purpose of further improving the sensitivity of the polymerization initiator or suppressing the inhibition of polymerization by oxygen. Examples of co-sensitizers include amines, and specific examples include triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline, and the like.

  The storage stabilizer may be added for the purpose of improving pot life. A known storage stabilizer can be used as the storage stabilizer.

  As the solvent, a known solvent can be used according to the purpose such as the polarity and viscosity of the primer ink, the surface tension, the solubility / dispersibility of the colorant, the adjustment of conductivity, and the adjustment of printing performance. Specifically, a high-boiling organic solvent can be used, and a high-boiling organic solvent having a property excellent in compatibility with constituent materials, particularly monomers, is particularly preferable.

  Other solvents include low-boiling organic solvents that are organic solvents at 100 ° C. or lower, but there is a concern that the curability may be affected, and it is desirable not to use them in consideration of environmental contamination by low-boiling organic solvents. When used, it is preferable to use a highly safe solvent. The “highly safe solvent” is a solvent having a high management concentration (an index indicated by the work environment evaluation standard), preferably having a management concentration of 100 ppm or more, and more preferably 200 ppm or more. Examples of the solvent having a high management concentration include alcohols, ketones, esters, ethers, hydrocarbons, and the like, specifically, methanol, 2-butanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, and the like. Can be mentioned.

  The above solvents can be used in combination other than one type alone, but when water and / or a low boiling point organic solvent is used, the amount of both used is 0 to 20 mass relative to the total amount of the ink. % Is preferable, 0 to 10% by mass is more preferable, and it is particularly preferable that the substance is not substantially contained. When the primer ink of the present invention is substantially free of water, it is non-permeable or slowly penetrable in terms of stability over time such as non-uniformity over time, turbidity of liquid due to precipitation of dyes, etc. This is preferable in terms of dryness when the above recording medium is used. In the present specification, “substantially does not contain” means to allow the presence of inevitable impurities.

  The gelation inhibitor may be added for the purpose of improving the storage stability. The anti-gelling agent is preferably added in an amount of 200 to 20,000 ppm relative to the total amount of ink. Specific examples of the gelation inhibitor include, for example, hydroquinone, benzoquinone, p-methoxyphenol, hydroquinone monomethyl ether, hydroquinone monobutyl ether, TEMPO, TEMPOL, cuperon; “IRGASTAB UV-10” manufactured by Ciba Special Chemicals, “IRGASTAB UV-22”; “FIRSTCURE ST-1” manufactured by ALBEMARLE;

  The primer ink of the present invention may further contain known additives such as polymers, ultraviolet absorbers, antioxidants, anti-fading agents and pH adjusters. As for the ultraviolet absorber, the antioxidant, the fading inhibitor, and the pH adjuster, known compounds may be appropriately selected and used. Specifically, for example, they are described in JP-A No. 2001-181549. Additives and the like can be used.

  The primer ink of the present invention is preferably transparent so as not to affect the drawability of the image forming ink described later. However, if the reproducibility is more excellent depending on the properties of the printed image, a colorant may be added. The content of the colorant added to the primer ink of the present invention is preferably 0.3 to 30% by mass, more preferably 0.5 to 25% by mass with respect to the total amount of the primer ink. A white colorant can be suitably used as the colorant. As the white colorant, the same white colorant that can be used in an image forming ink described later can be used. Further, when dispersing the colorant, a dispersant, a dispersion aid, a solvent, and the like can be added, and these can be the same as the image forming ink described later.

(Image forming method)
Next, an image forming method using the primer ink of the present invention will be described.

  The image forming method of the present invention includes a step of applying the above-described primer ink of the present invention on a recording medium, and an image forming ink by an inkjet method on a portion of the recording medium to which the primer ink is applied. And a step of forming an image. This image forming method is also called an ink jet recording method because an image is formed by an ink jet method using the image forming ink composition.

  As the image forming ink, a conventionally known inkjet ink containing at least a colorant is used. As the colorant, various pigments are used, and an ink using an energy ray-curable polymerizable compound is preferably used for dispersing them. This will be described later.

  In this specification, “image” refers to optical information including characters, diagrams, photographs, and the like, and may be monochrome, monocolor, or full color. The “image forming ink” refers to a multicolor ink set comprising a plurality of image forming ink compositions (hereinafter also simply referred to as inks or ink liquids). When an image is formed, an image may be formed by ejecting only one color image forming ink composition, but in order to form a full color image, a plurality of color image forming ink compositions are sequentially or simultaneously formed. An image is formed by discharging.

  In general, in the ink jet recording method, adjacent ink droplets that are applied with overlapping portions to obtain a high image density stay on and contact the recording medium before drying. Are merged with each other to cause blurring of the image and non-uniformity of the line width of the fine lines, and the sharp image forming property is easily impaired. On the other hand, in the present invention, the ink liquid is applied to the portion of the recording medium to which the primer ink has been applied by previously applying the primer ink to the portion to which the image forming ink composition is to be applied. Even if the droplets are applied with overlapping portions, the coalescence between these adjacent ink droplets can be suppressed by the interaction between the primer ink and the ink droplet. This effectively prevents the occurrence of blurring of the image, non-uniform line widths such as fine lines in the image, and color unevenness on the colored surface. Therefore, when recording an image on a hard-to-adhere recording medium made of a non-permeable or slow-permeable synthetic resin having low liquid absorbency, the primer ink of the present invention improves the image adhesiveness, which is particularly effective. It is.

  Here, “adjacent ink droplets” are droplets that are ejected from an ink ejection port using a single color ink and are ejected with overlapping portions, or inks of different colors Is a droplet ejected from the ink ejection port using the, and is ejected with an overlapping portion. Adjacent ink droplets may be droplets that are ejected at the same time, or may be preceding droplets and subsequent droplets that have a relationship between preceding droplet ejection and subsequent droplet ejection.

  One of the specific configurations of the ink jet recording method of the present invention is that the multi-color image forming ink composition constituting the image forming ink ejected onto the recording medium contains a polymerizable compound. Applying the primer ink of the present invention to the same or wider range than the image formed using the image-forming ink droplets, and applying energy to the primer ink applied on the recording medium. And a step of curing by applying a line or heat, and a step of ejecting the ink composition for forming a plurality of colors on the portion of the recording medium to which the primer ink is applied.

  Furthermore, from the viewpoint of obtaining excellent image fixability, it is preferable to provide a step of applying energy after droplets of all of the above-described plural color image forming ink compositions are ejected. By applying energy, a curing reaction by polymerization or crosslinking of the polymerizable compound contained in each of the image forming ink compositions can be promoted, and a stronger image can be formed more efficiently. When the image-forming ink composition further contains a polymerization initiator, generation of active species from the polymerization initiator is promoted by application of energy such as energy beam irradiation and heating, and the increase in active species and temperature increase. The curing reaction by polymerization or crosslinking of the polymerizable compound resulting from the active species is promoted.

  Application of energy can be suitably performed by irradiation of conventionally known energy rays or heating. As the energy ray, the same light as the active light for fixing the image can be used, for example, LED light, ultraviolet light, visible light, etc., as well as α ray, γ ray, X ray, electron beam, etc. From the viewpoint of cost and safety, ultraviolet rays and visible rays are preferable. Suitable light sources for exposure include metal halide lamps, xenon lamps, tungsten lamps, carbon arc lamps, mercury lamps and the like.

When the energy is applied by irradiation with active light, the amount of energy required for curing reaction varies depending on the type and content of the polymerization initiator, the degree typically 100 mJ / cm ² or more 10,000 / cm ² or less preferable. In addition, when energy is applied by heating, it is preferable to heat for 0.1 to 1 second under the condition that the surface temperature of the recording medium is in a temperature range of 40 to 80 ° C.

(Image forming ink)
The image forming ink composition constituting the image forming ink of the present invention is configured to have at least a composition for forming an image, and includes a polymerizable compound, a polymerization initiator, and a colorant. .

<Polymerizable compound>
The polymerizable compound constituting the image-forming ink composition of the present invention has a function of causing polymerization or cross-linking reaction by an initiation species such as a radical generated from a polymerization initiator described later, and curing a composition containing these. It is what has.

  As the polymerizable compound, a compound that causes a known polymerization or crosslinking reaction such as radical polymerization reaction or dimerization reaction to be cured can be applied. For example, an addition polymerizable compound having at least one ethylenically unsaturated double bond, a polymer compound having a maleimide group in the side chain, a cinnamyl group having a photodimerizable unsaturated double bond adjacent to the aromatic ring, Examples thereof include a polymer compound having a cinnamylidene group or a chalcone group in the side chain. Among these, an addition polymerizable compound having at least one ethylenically unsaturated double bond is more preferable, and from a compound (monofunctional or polyfunctional compound) having at least one terminal ethylenically unsaturated bond, more preferably two or more. It is particularly preferred that it is selected. Specifically, it can be appropriately selected from those widely known in the industrial field according to the present invention. For example, monomers, prepolymers (that is, dimers, trimers, and oligomers) and mixtures thereof, and those Those having a chemical form such as a copolymer of Moreover, the said polymeric compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The polymerizable compound constituting the image-forming ink composition of the present invention is preferably a variety of known radically polymerizable monomers (hereinafter referred to as radicals) that cause a polymerization reaction by an initiation species generated from a radical polymerization initiator and cure. And a variety of known cationically polymerizable compounds that cause a polymerization reaction by an initiation species generated from a cationic polymerization initiator and are cured, or both of them can be used in combination.

[Radically polymerizable compound]
The radical polymerizable compound that can be used in the image-forming ink composition of the present invention is preferably an ethylenically unsaturated compound. Examples of the ethylenically unsaturated compound include (meth) acrylates, (meth) acrylamides, aromatic vinyls, vinyl ethers, and compounds having an internal double bond (such as maleic acid). Here, “(meth) acrylate” refers to both and / or “acrylate” and “methacrylate”, and “(meth) acryl” refers to both and / or “acryl” and “methacryl”.

  Examples of the (meth) acrylates include the following.

  Specific examples of monofunctional (meth) acrylates include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) ) Acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate 2-ethylhexyl diglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, cyano Chill (meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl (meth) acrylate, 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, 4 -Butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate Relate, 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-hydroxybutyl (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-methacryloyloxytyl succinate Acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methac Leuoxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate (2-HPA EO-modified phenol (meth) acrylate, EO-modified cresol (meth) acrylate, EO-modified nonylphenol (meth) acrylate, PO-modified nonylphenol (meth) acrylate, EO-modified-2-ethylhexyl (meth) acrylate, and the like.

  Specific examples of the bifunctional (meth) acrylate include 1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 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, hydroxypivalic acid neopentyl glycol di (meth) acrylate, 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 ( Examples include meth) acrylate, 1,9-nonanedi (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, and tricyclodecane di (meth) acrylate.

  Specific examples of trifunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane alkylene oxide-modified tri (meth) acrylate, pentaerythritol tri (meth) acrylate , Dipentaerythritol tri (meth) acrylate, trimethylolpropane tris ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, propionate dipentaerythritol tri (meth) acrylate, tris ((meta) ) Acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) Acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and the like ethoxylated glycerol triacrylate.

  Specific examples of tetrafunctional (meth) acrylates include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, propionate dipentaerythritol tetra (meth) acrylate, ethoxylated penta Examples include erythritol tetra (meth) acrylate.

  Specific examples of the pentafunctional (meth) acrylate include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.

  Specific examples of hexafunctional (meth) acrylate include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide modified hexa (meth) acrylate, captolactone modified dipentaerythritol hexa (meth) acrylate And so on.

  Specific examples of the (meth) acrylamide compound include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, and Nn-butyl (meth) acrylamide. N-t-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N- Examples include diethyl (meth) acrylamide and (meth) acryloylmorpholine.

  Specific examples of the aromatic vinyls include 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. Acid methyl ester, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4 -Hexylstyrene, 3-octylstyrene, 4-octylstyrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allylstyrene, isopropenylstyrene, butenylstyrene, octene Rusuchiren, 4-t-butoxycarbonyl styrene, 4-methoxystyrene, and the like 4-t-butoxystyrene.

  Examples of the vinyl ethers include the following.

  Examples of monofunctional vinyl ethers 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, cyclohexyl methyl vinyl ether, 4- Methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, 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, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl Examples include vinyl ether, phenylethyl vinyl ether, phenoxy polyethylene glycol vinyl ether, and the like.

  Examples of polyfunctional vinyl ethers 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 di Divinyl ethers such as vinyl ether; 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-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide-added penta And polyfunctional vinyl ethers such as erythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

  Among the vinyl ethers, a divinyl ether compound or a trivinyl ether compound is preferable from the viewpoint of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and a divinyl ether compound is particularly preferable.

  Examples of the radical polymerizable compound that can be used in the image-forming ink composition of the present invention include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl versatate, allyl esters such as allyl acetate; And halogen-containing monomers such as vinylidene chloride and vinyl chloride; vinyl cyanides such as (meth) acrylonitrile; olefins such as ethylene and propylene; and the like.

[Cationically polymerizable compound]
The cationically polymerizable compound that can be used in the image forming ink composition of the present invention is not particularly limited as long as it is a compound that causes a cationic polymerization reaction by being given some energy and cures. The cationically polymerizable compound can be used regardless of the type of monomer, oligomer or polymer, and may be a monofunctional compound or a polyfunctional compound. In particular, various known cationically polymerizable monomers known as photocationically polymerizable monomers that cause a polymerization reaction with an initiation species generated from a cationic polymerization initiator described later can be used.

  Examples of the cationic polymerizable monomer include, for example, JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-2001. Epoxy compounds, vinyl ether compounds, oxetane compounds and the like described in JP-A No. -310937 and JP-A No. 2001-220526.

  Specific examples of the epoxy compound include the following.

  Examples of monofunctional epoxy compounds 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. Monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, 3-vinylcyclohexene oxide, etc. Is mentioned.

  Examples of polyfunctional epoxy compounds 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 di Glycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl) -7,8-epoxy-1,3-dioxaspiro [5.5] undecane, bis (3,4-epoxycyclohexylme A) 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, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylenebis (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, 1,13-tetradecadiene dioxide, limonene dioxide, 1,2,7,8-diepoxyoctane, 1,2,5,6-diepoxycyclooctane and the like. Among these epoxy compounds, aromatic epoxides and alicyclic epoxides are preferable from the viewpoint of excellent curing speed, and alicyclic epoxides are particularly preferable.

  Specific examples of the vinyl ether compound include the following.

  Examples of monofunctional vinyl ethers include, for example, 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, cyclohexyl methyl vinyl ether, 4 -Methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl D Ter, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloro Examples thereof include ethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxy polyethylene glycol vinyl ether and the like.

  Examples of polyfunctional vinyl ethers include, 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 F alkylene oxide. Divinyl ethers such as divinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hex Vinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide-added penta Multifunctional vinyl ethers such as erythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether;

  Among the above-mentioned compounds, the vinyl ether compound is preferably a divinyl ether compound or a trivinyl ether compound from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like. preferable.

  As the oxetane compound, a known oxetane compound can be arbitrarily selected and used as described in JP-A-2001-220526, JP-A-2001-310937, and JP-A-2003-341217. Here, the “oxetane compound” is a compound containing at least one oxetane ring (oxetanyl group) in the molecule.

  As said oxetane compound, the oxetane compound which has 1-4 oxetane rings in the structure is preferable. By using such an oxetane compound, it becomes easy to maintain the viscosity of the ink composition for image formation in a favorable range of handling properties, and high adhesion between the formed image and the recording medium is achieved. Can be obtained.

  Specific examples of the oxetane compound include the following.

  Examples of monofunctional oxetane compounds include, for example, 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy) methylbenzene, 4- Fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl [benzene, 4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-ethyl-3- Oxetanylmethoxy) ethyl] phenyl ether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3-oxetanylmethyl) ) Ether, 2-ethylhexyl (3-ethyl-3-oxe) Nylmethyl) ether, ethyldiethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, Dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxy Ethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl (3-ethyl-3-oxetanylmethyl) 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.

  Examples of polyfunctional oxetane compounds include, for example, 3,7-bis (3-oxetanyl) -5-oxa-nonane, 3,3 ′-(1,3- (2-methylenyl) propanediylbis (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, dicyclopentenylbis (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-e Ru-3-oxetanylmethyl) ether, dipentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol pentane Kis (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 Ethyl-3-oxetanylmethyl) ether, polyfunctional oxetane such as EO-modified bisphenol F (3- ethyl-3-oxetanylmethyl) ether.

  As such oxetane compounds, those described in detail in paragraphs 0021 to 0084 of JP-A-2003-341217 can be preferably used.

  Among the oxetane compounds, it is preferable to use a compound having 1 to 2 oxetane rings from the viewpoint of the viscosity and tackiness of the image forming ink composition.

  The cationically polymerizable compound that can be used in the image forming ink composition of the present invention is preferably an oxirane compound and an oxetane compound from the viewpoint of curability and scratch resistance, and contains both an oxirane compound and an oxetane compound. Is more preferable. Here, the “oxirane compound” refers to a compound containing at least one oxirane ring (oxiranyl group, epoxy group) in the molecule, and specifically from those normally used as epoxy resins. Examples thereof include conventionally known aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. The polymerizable compound containing the oxirane compound may be any of a monomer, an oligomer and a polymer.

  The cationically polymerizable compound described above may be used alone or in combination of two or more.

  The content of the cationic polymerizable compound is preferably in the range of 50 to 95% by mass, and more preferably in the range of 60 to 92% by mass, based on the total solid content in the image forming ink composition.

<Polymerization initiator>
The polymerization initiator constituting the image forming ink composition of the present invention is preferably one that initiates a polymerization reaction or crosslinking reaction with heat or energy rays, and more preferably one that initiates a polymerization reaction or crosslinking reaction with energy rays. . When the image forming ink composition contains a polymerization initiator, the image forming ink composition applied to the recording medium can be cured by irradiation with energy rays or heating.

  The polymerization initiator contains a polymerization initiator (radical polymerization initiator) that causes radical polymerization when the polymerizable compound constituting the image forming ink composition of the invention is the radical polymerizable compound. Preferably, when the polymerizable compound is the cationic polymerizable compound, it preferably contains a polymerization initiator (cationic polymerization initiator) that causes cationic polymerization, and these are photopolymerization initiators. Is particularly preferred.

As said photoinitiator, the same thing as the primer ink of this invention mentioned above can be used. Among the above-mentioned photopolymerization initiators, the radical polymerization initiator is preferably an aromatic ketone, more preferably a compound having a benzophenone skeleton or a thioxanthone skeleton, an α-aminoalkylphenone compound, an acyl. A phosphine oxide compound is particularly preferred. Among the above photopolymerization initiators, the cationic polymerization initiator is preferably an aromatic onium salt, more preferably an iodonium salt or a sulfonium salt, and a PF ₆ salt of an iodonium salt or a PF of a sulfonium salt. _Six salts are particularly preferred.

  The cationic polymerization initiator or the radical polymerization initiator can be used alone or in combination of two or more. Further, as long as the effects of the present invention are not impaired, a known sensitizer can be used in combination for the purpose of improving the sensitivity of the polymerization initiator.

  The content of the cationic polymerization initiator or the radical polymerization initiator is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total solid content in the image forming ink composition. .

  In the image forming ink composition of the invention, the content ratio (mass ratio) of the polymerization initiator and the polymerizable compound is preferably 0.5: 100 to 30: 100, and 1: 100 to 15. : 100 is more preferable.

<Colorant>
As described above, the image forming ink of the present invention is a multi-color ink set comprising a plurality of image forming ink compositions, and includes a cyan ink composition (cyan ink composition) and a magenta ink composition. (Magenta ink composition), yellow ink composition (yellow ink composition), black ink composition (black ink composition), and white ink composition (white ink composition) It is preferable to include at least one image forming ink composition.

  Basically, the image forming ink is preferably a multicolor ink set including a cyan ink composition, a magenta ink composition, a yellow ink composition, a black ink composition, and a white ink composition. This is a multicolor ink set capable of forming an image with excellent color reproducibility by using an image forming ink composition containing a colorant exhibiting violet, blue, green, orange and red colors. It is preferable.

  Accordingly, the image forming ink composition of the present invention preferably contains at least one colorant. Each color image-forming ink composition contains at least one colorant exhibiting each corresponding color.

  The colorant is not particularly limited and may be appropriately selected from known water-soluble dyes, oil-soluble dyes, pigments, and the like. However, the image-forming ink composition of the present invention is non-aqueous. Oil-soluble dyes and pigments that are easily dispersed and dissolved in a water-insoluble medium are preferred.

  Next, pigments suitable for the image forming ink composition of the invention will be described. As the pigment, either an organic pigment or an inorganic pigment can be used. Inorganic pigments include, for example, titanium oxide, zinc white, zinc oxide, tripone, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, cadmium red, red rose, molybdenum Red, chrome vermilion, molybdate orange, yellow lead, chrome yellow, cadmium yellow, yellow iron oxide, titanium yellow, chrome oxide, pyridian, cobalt green, titanium cobalt green, cobalt chrome green, ultramarine blue, ultramarine blue, bitumen, Examples include cobalt blue, cerulean blue, manganese violet, cobalt violet, and mica. Examples of the organic pigment include organic pigments such as azo, azomethine, polyazo, phthalocyanine, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimidazolone, and isoindoline. Carbon black made of acidic, neutral or basic carbon may be used. Furthermore, a hollow particle of a crosslinked acrylic resin or the like may be used as the organic pigment.

  In the image forming ink composition of the present invention, pigments of three primary colors of black and cyan, magenta, and yellow are usually used. However, pigments having other hues, metallic luster pigments such as gold and silver, Colorless or pale extender pigments can also be used depending on the purpose.

  First, a description will be given of a pigment that uses a primary color (magenta, cyan, yellow) plus black or white as a basic color. Specific examples of the pigment include compounds classified as pigments in the color index (CI: issued by The Society of Dyers and Colorists), that is, the color index (CI) as shown below. Those with numbers are listed.

  Examples of the pigment exhibiting the magenta color include C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (such as Lake Red C) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment Violet 19 (unsubstituted quinacridone, “CINQUASIA Magenta RT-355T” manufactured by Ciba Specialty Chemicals), C.I. I. Quinacridone pigments such as C.I. Pigment Red 122 (such as quinacridone magenta); I. Isoindolinone pigments such as C.I. Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

  Examples of the pigment exhibiting the cyan color include C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (eg, dianisidine blue); I. Pigment blue 15, C.I. I. Phthalocyanine pigments such as CI Pigment Blue 15: 3 (“IRGALITE BLUE GLO” manufactured by Ciba Specialty Chemicals) (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (such as Peacock Blue Lake); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

  Examples of the yellow pigment include C.I. I. Pigment Yellow 1 (Fast Yellow G, etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (such as Disaji Yellow AAA), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Pigment yellow 180, C.I. I. Non-benzidine type azo pigments such as C.I. Pigment Yellow 200 (Novoperm Yellow 2HG); I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (such as Nickel Nitroso Yellow); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  Examples of the black pigment include carbon black, titanium black, and aniline black. An example of carbon black is “SPECIAL BLACK 250” manufactured by Degussa.

Examples of the white pigment include Pigment White 6, 18, and 21. 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), titanium oxide (TiO ₂ , so-called titanium white). ), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) and the like can be used.

  Here, the titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a high hiding power and coloring power as a pigment. Excellent durability against alkalis and other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

  Among the pigments exemplified above, the pigment exhibiting cyan color is preferably pigment blue 15: 3 or pigment blue 15: 4, and the pigment exhibiting magenta color is pigment red 122, pigment red 202 or pigment violet 19. It is preferable that pigments exhibiting a yellow color are Pigment Yellow 150, Pigment Yellow 180, and Pigment Yellow 155. Moreover, it is preferable that the pigment which exhibits white is a titanium oxide.

  Next, in order to form an image excellent in color reproducibility, a pigment exhibiting violet color, blue color, green color, orange color, red color or the like that is used in some cases will be described.

  Examples of the pigment exhibiting the violet color include C.I. I. Pigment violet 1 (rhodamine B), C.I. I. Pigment violet 2 (rhodamine 3B), C.I. I. Pigment violet 3 (methyl violet lake), C.I. I. Pigment violet 3: 1 (methyl violet lake), C.I. I. Pigment violet 3: 3 (methyl violet lake), C.I. I. Pigment Violet 5: 1 (Alizarin Maroon), C.I. I. Pigment violet 13 (ultramarine pink), C.I. I. Pigment violet 17 (naphthol AS), C.I. I. Pigment violet 23 (dioxazine violet), C.I. I. Pigment violet 25 (naphthol AS), C.I. I. Pigment violet 29 (perylene violet), C.I. I. Pigment violet 31 (violanslon violet), C.I. I. Pigment Violet 32 (Benzimidazolone Bordeaux HF3R), C.I. I. Pigment violet 36 (thioindigo), C.I. I. Pigment violet 37 (dioxazine violet), C.I. I. Pigment Violet 42 (Quinacridone Maroon B), C.I. I. Pigment Violet 50 (Naphthol AS) and the like are commercially available.

  Examples of the blue pigment include C.I. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. Pigment blue 60, C.I. I. Pigment Blue 66 and the like are commercially available.

  Examples of the green pigment include C.I. Pigment Green 1 (Brilliant Green Lake), C.I. Pigment Green 4 (Malachite Green Lake), C.I. Pigment Green 7 (phthalocyanine green), C.I. Pigment Green 8 (Pigment Green B), C.I. Pigment green 10 (nickel azo yellow), C.I. I. Pigment Green 36 (brominated phthalocyanine green) and the like are commercially available.

  Examples of the orange pigment include C.I. I. Pigment Orange 1 (Hansa Yellow 3R), C.I. I. Pigment orange 2 (orthonitro orange), C.I. I. Pigment orange 3 (β-naphthol), C.I. I. Pigment Orange 4 (Naphthol AS), C.I. I. Pigment orange 5 (β-naphthol), C.I. I. Pigment orange 13 (pyrazolone orange G), C.I. I. Pigment orange 15 (disazo orange), C.I. I. Pigment orange 16 (anisidine orange), C.I. I. Pigment Orange 17 (Persian Orange Lake), C.I. I. Pigment Orange 19 (Naphthalene Yellow Lake), C.I. I. Pigment orange 24 (naphthol orange Y), C.I. I. Pigment orange 31 (condensed azo orange), C.I. I. Pigment orange 34 (piazolone orange), C.I. I. Pigment Orange 36 (Benzimidazolone Orange HL), C.I. I. Pigment orange 38 (naphthol orange), C.I. I. Pigment orange 40 (pyranthron orange), C.I. I. Pigment orange 43 (perinone orange), C.I. I. Pigment Orange 46 (Ethyl Red Lake C), C.I. I. Pigment orange 48 (quinacridone gold), C.I. I. Pigment Orange 49 (Quinacridone Gold), C.I. I. Pigment orange 51 (pyranthrone orange), C.I. I. Pigment Orange 60 (Imidazolone Orange HGL), C.I. I. Pigment orange 61 (isoindolinone orange), C.I. I. Pigment Orange 62 (Benzimidazolone Orange H5G), C.I. I. Pigment orange 64 (benzimidazolone), C.I. I. Pigment orange 65 (azomethine orange), C.I. I. Pigment Orange 66 (Isoindori Orange), C.I. I. Pigment orange 67 (pyrazoloquinazolone orange), C.I. I. Pigment orange 68 (azomethine orange), C.I. I. Pigment orange 69 (isoindolinone orange), C.I. I. Pigment orange 71 (diketopyrrolopyrrole orange), C.I. I. Pigment orange 72 (imidazolone orange H4GL), C.I. I. Pigment orange 73 (diketopyrrolopyrrole orange), C.I. I. Pigment orange 74 (naphthol orange 2RLD), C.I. I. Pigment Orange 81 (diketopyrrolopyrrole orange) and the like are commercially available.

  Examples of the red pigment include C.I. I. Pigment red 171, C.I. I. Pigment red 175, C.I. I. Pigment red 176, C.I. I. Pigment red 177, C.I. I. Pigment red 209, C.I. I. Pigment red 220, C.I. I. Pigment red 224, C.I. I. Pigment red 242, C.I. I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. Pigment red 264, C.I. I. Pigment Red 270 and the like are commercially available.

  Among the pigments exemplified above, from the viewpoint of color reproducibility, light resistance, and pigment dispersion stability, C.I. I. Pigment Violet 23 is preferred, and the orange pigment is C.I. I. Pigment orange 36, C.I. I. Pigment Orange 71 is preferable, and a pigment exhibiting a green color is C.I. I. Pigment green 7, C.I. I. Pigment Green 36 is preferable.

  As the image forming ink of the present invention, an image forming ink composition containing a pigment and / or a dye exhibiting a basic color of magenta, cyan, yellow, black or white as described above; It is preferable to use an image-forming ink composition containing a pigment exhibiting a color (violet, blue, green, orange, red, etc.).

  The colorant may be used alone or in combination of two or more. In the present invention, two or more kinds of organic pigments or solid solutions of organic pigments can be used in combination. Different colorants may be used for each droplet and liquid to be ejected, or the same colorant may be used.

  For the dispersion of the colorant, for example, bead mill, ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, etc. An apparatus can be used.

  When dispersing the colorant, a dispersant can be added. The type of the dispersant is not particularly limited, but a known polymer dispersant is preferably used. Examples of the polymer dispersant include “DisperBYK-101”, “DisperBYK-102”, “DisperBYK-103”, “DisperBYK-106”, “DisperBYK-111”, “DisperBYK-161”, and “DisperBYK” manufactured by BYK Chemie. -162 "," DisperBYK-163 "," DisperBYK-164 "," DisperBYK-166 "," DisperBYK-167 "," DisperBYK-168 "," DisperBYK-170 "," DisperBYK-171 "," DisperBYK-1 " "DisperBYK-182"; "EFKA4010", "EFKA4046", "EFKA4080", "EFKA5010", "Efka Additives" “FKA5207”, “EFKA5244”, “EFKA6745”, “EFKA6750”, “EFKA7414”, “EFKA7462”, “EFKA7500”, “EFKA7570”, “EFKA7575”, “EFKA7580”; “Disperse Aid 8”, “Disperse Aid 15”, “Disperse Aid 9100”; “Solsperse 3000”, “Solspers 5000”, “Solspers 9000”, “Solspers 12000”, “Solspers” manufactured by Abyssia 13240 "," Sol Sparse 13940 "," Sol Sparse 17000 "," Sol Sparse 24000 "," Sol Sparse 26000 "," Sol Sparse 28000 "," Sol Spa "32000", "Sol Sparse 36000", "Sol Sparse 39000", "Sol Sparse 41000", "Sol Sparse 71000"; "Adeka Pluronic L31", "F38", "L42", "L44", "L61" manufactured by Asahi Denka , “L64”, “F68”, “L72”, “P95”, “F77”, “P84”, “F87”, “P94”, “L101”, “P103”, “F108”, “L121”, “ “Isonet S-20” manufactured by Sanyo Kasei Co., Ltd .; “Disparon KS-860”, “873SN”, “874” (polymer dispersing agent), “# 2150” (aliphatic) manufactured by Enomoto Kasei Co., Ltd. Polyvalent carboxylic acid), “# 7004” (polyether ester type), and the like.

  The dispersant may be used in combination with pigment derivatives such as phthalocyanine derivative “EFKA-745” manufactured by Efka, “Solsperse 5000”, “Solsperse 12000”, and “Solsperse 22000” manufactured by Abyssia.

  The content of the dispersant is appropriately selected depending on the purpose of use, and can be set to 0.01 to 5% by mass with respect to the total amount of the image forming ink composition, for example.

  Moreover, when adding the said coloring agent, it is also possible to use the synergist according to various coloring agents as a dispersing aid as needed.

  Moreover, as a dispersion medium of various components, such as the said coloring agent, a solvent may be added and the polymeric compound which is a low molecular weight component without a solvent may be used as a dispersion medium. However, in the present invention, since the image forming ink and / or primer ink is applied onto the recording medium and then cured, it is preferably solventless. This is because if the solvent remains in the formed image, the solvent resistance deteriorates, and volatile organic compounds (VOC) contained in the remaining solvent cause air pollution. is there. From such a point of view, a polymerizable compound is used as the dispersion medium, and among them, it is preferable to select a polymerizable compound having a low viscosity from the viewpoint of improving dispersibility and handling properties of the image forming ink.

  The average particle size of the colorant is preferably 0.01 μm or more and 0.4 μm or less, and more preferably 0.02 μm or more and 0.2 μm or less because the finer the particle size, the better the color developability. It is preferable to set the colorant, dispersant, dispersion medium, dispersion conditions, and filtration conditions so that the maximum particle size is preferably 3 μm or less, more preferably 1 μm or less. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, transparency, and curing sensitivity can be maintained. In the present invention, a uniform and stable dispersion can be obtained even when a fine particle colorant is used by using the above-mentioned dispersant having excellent dispersibility and stability. The particle diameter of the colorant in the ink can be measured by a known measurement method. Specifically, it can be measured by a centrifugal sedimentation light transmission method, an X-ray transmission method, a laser diffraction / scattering method, and a dynamic light scattering method.

  The content of the colorant is appropriately selected depending on the color and purpose of use, but from the viewpoint of image density and storage stability, it is 0.3 to 30% by mass with respect to the total amount of the image forming ink composition. Is preferable, and it is more preferable that it is 0.5-20 mass%.

  It is preferable to add a surface conditioner to the ink composition for image formation of the present invention for the purpose of imparting a stable discharge property for a long time. As the surface conditioner, the same surface conditioner that can be used in the primer ink of the present invention described above can be used. The content of the surface conditioner is appropriately selected depending on the purpose of use, but generally it is preferably 0.0001 to 1% by mass relative to the total amount of the image forming ink composition.

  A sensitizer may be added to the ink composition for image formation of the present invention for the purpose of improving the sensitivity of the polymerization initiator. As the sensitizer, the same sensitizer that can be used in the primer ink of the present invention described above can be used.

  In addition to the above components, a co-sensitizer, a storage stabilizer, a solvent, an anti-gelling agent, and other additives can be added to the image forming ink composition of the present invention depending on the purpose.

  The co-sensitizer can be added for the purpose of further improving the sensitivity of the polymerization initiator or suppressing the inhibition of polymerization by oxygen. As a specific example of the co-sensitizer, the same co-sensitizer that can be used in the primer ink of the present invention described above can be used.

  The storage stabilizer may be added for the purpose of improving pot life. A known storage stabilizer can be used as the storage stabilizer.

  Examples of the solvent include known solvents depending on purposes such as polarity and viscosity of the image forming ink composition, surface tension, solubility / dispersibility of the colorant, adjustment of conductivity, and adjustment of printing performance. Can be used. Specific examples of the solvent include solvents that can be used in the primer ink of the present invention described above.

  The above solvents can be used in combination other than one kind alone, but when water and / or a low boiling point organic solvent is used, the amount of both used is preferably 0 to 20% by mass in each liquid. 0 to 10% by mass is more preferable, and it is particularly preferable that the content is not substantially contained. When the ink composition for image formation is substantially free of water, it is more stable over time, such as non-uniformity over time, turbidity of liquid due to precipitation of dyes, etc. This is preferable in terms of dryness when using a recording medium with good characteristics.

  The above-mentioned gelation inhibitor can be added from the viewpoint of improving the storage stability. The ink composition for image formation is preferably heated and reduced in viscosity within a range of 40 to 80 ° C. and discharged, and an antigelling agent is preferably added to prevent clogging of the head due to thermal polymerization. The gelation inhibitor is preferably added in an amount of 200 to 20,000 ppm based on the total amount of the image forming ink composition. Specific examples of the antigelling agent include the same antigelling agents that can be used in the primer ink of the present invention described above.

  Similarly to the primer ink of the present invention described above, the image forming ink composition of the present invention is further added with known additives such as polymers, ultraviolet absorbers, antioxidants, anti-fading agents, and pH adjusters. May be.

(Physical properties of primer ink and image forming ink)
The viscosity and surface tension of the primer ink and image forming ink of the present invention are appropriately adjusted according to the application method and apparatus to the recording medium. The surface tension of the primer ink is preferably larger than that of the image forming ink.

  When the primer ink of the present invention is applied onto a recording medium by an ink jet method, the viscosity (25 ° C.) of the primer ink of the present invention is preferably 50 mPa · s or less. Although the lower limit of a viscosity is not specifically limited, For example, it can be set with 1.0 mPa * s.

  When the primer ink of the present invention is applied onto a recording medium by an ink jet method, the surface tension of the primer ink of the present invention is preferably 25 to 31 mN / m. This range is preferred because if it is less than 25 mN / m, the ink may spread easily and spread during image formation, and if it exceeds 31 mN / m, the ink may easily repel during image formation and an image may not be drawn. It is. Furthermore, if the range of 25 to 31 mN / m is greatly deviated, it is not suitable for an ink jet printer, resulting in ejection failure.

(Recording medium)
As the recording medium, any of a permeable recording medium, a non-permeable recording medium, and a slowly permeable recording medium can be used, but the effect of the present invention is more remarkably exhibited. From the viewpoint of recording, a non-permeable or slowly permeable recording medium is preferable.

  Here, the “penetrable recording medium” means, for example, a recording medium whose time until the entire liquid amount permeates is 100 ms or less when a droplet of 10 pL (picoliter) is dropped on the recording medium. A recording medium. Further, “non-permeable recording medium” refers to a recording medium in which droplets do not substantially permeate. “Substantially does not penetrate” means, for example, that the penetration rate of a droplet after 1 minute is 5% or less. In addition, “slowly permeable recording medium” refers to a recording medium in which when a 10 pL droplet is dropped on the recording medium, the time until the entire liquid amount penetrates is 100 ms or more.

  Examples of the permeable recording medium include plain paper, porous paper, and other recording media that can absorb liquid. Examples of the non-permeable or slowly permeable recording medium include synthetic resin, resin-coated paper, metal, art paper, rubber, glass, earthenware, and wood. In the present invention, a recording medium in which a plurality of these materials are combined and combined can be used for the purpose of adding functions.

  Any synthetic resin can be used as the synthetic resin that can be used as the non-permeable or slowly permeable recording medium. For example, polyesters such as polyethylene terephthalate (PET) and polybutadiene terephthalate, and polyvinyl chloride (PVC). , Polyolefins such as polystyrene (PS), polyethylene (PE), polyurethane (PU), polypropylene (PP), acrylic resin, polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) copolymer, diacetate, triacetate, Examples include 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 transparent or opaque. Good.

  The synthetic resin is preferably used in the form of a film used for so-called soft packaging, and various non-permeable plastics and films thereof can be used. Examples of the plastic film include a PET film, a biaxially stretched polystyrene (OPS) film, a biaxially stretched polypropylene (OPP) film, a nylon film, a PVC film, a PE film, a triacetyl cellulose (TAC) film, and a PP film. Can be mentioned. Other plastics that can be used include PC, acrylic resin, ABS resin, polyacetal resin, polyvinyl alcohol (PVA) resin, and rubbers.

  Examples of the resin-coated paper that can be used as the non-permeable or slowly permeable recording medium include a transparent polyester film, an opaque polyester film, an opaque polyolefin resin film, and a paper support in which both sides of the paper are laminated with a polyolefin resin. Can be mentioned. Particularly preferred is a paper support in which both sides of the paper are laminated with a polyolefin resin.

  The metal that can be used as the above-mentioned non-permeable or slow-permeable recording medium is not particularly limited. For example, aluminum, iron, gold, silver, copper, nickel, titanium, chromium, molybdenum, silicon, lead, zinc, etc. And stainless steel, and composite materials thereof.

(Primer ink curing process)
In the present invention, the primer ink itself can also be applied to a recording medium by an ink jet method, and in this case, the primer ink is used as one of multicolor ink sets including a plurality of color ink forming ink compositions. Is preferred. Therefore, the curing process of the primer ink is determined by the configuration of the ink jet recording method and apparatus.

  In other words, if the inkjet recording method / device is a method in which a head dedicated to primer ink and a radiation irradiation device are installed in a single scan (single pass), an image is formed on the primer ink after the primer ink is cured. Ink for ink will be applied. In the case of applying the primer ink almost simultaneously with the image forming ink in the multi-pass method, the image forming ink is ejected after the primer ink is cured, although there is a slight time difference. The primer ink of the present invention may be of any type, but the latter type is preferred from an industrial viewpoint in terms of operability and productivity.

(Application of primer ink and ink composition for image formation)
Examples of the method for applying the primer ink of the present invention to a recording medium include the method of droplet ejection or coating as described above. Specific examples include ink jet, gravure, flexo, pad, screen, and offset printing methods. Among these, ink jet and flexo are preferably used. On the other hand, the method for applying the image forming ink of the present invention to a recording medium is droplet ejection by an inkjet method.

  When the primer ink and image forming ink of the present invention are applied by droplet ejection, an inkjet nozzle is used. In this case, first, the primer ink is ejected onto the recording medium by the ink jet nozzle, and there is a slight time difference, but the image forming ink is almost simultaneously applied to the portion of the recording medium to which the primer ink is applied by the ink jet nozzle. An image is formed by droplet ejection.

  When applying the primer ink using the inkjet nozzle, for example, a head having a larger ejection droplet amount and a lower nozzle density than the head for ejecting ink liquid is arranged as a full line head unit in the width direction of the recording medium, Thereby, the primer ink is discharged.

  Such a head with a large amount of ejected droplets generally has a large ejection force, and therefore can easily cope with a highly viscous primer ink, and is also advantageous in suppressing nozzle clogging. In addition, when a head with a large amount of ejected droplets is used, there is an advantage that an inexpensive head with a low driving frequency can be applied because the droplet resolving power of the primer ink in the recording medium conveyance direction can be reduced.

  On the other hand, when applying the primer ink of the present invention by coating, a coating apparatus is used. In this case, the primer ink is applied onto the recording medium using a coating device, and then the ink for image formation is ejected onto the portion of the recording medium to which the primer ink has been applied by an inkjet nozzle, Form an image.

  In any of the above embodiments, liquids other than the image forming ink and the primer ink can be further applied. The application of the other liquid may be applied to the recording medium by any method such as application by an application device or ejection by an ink jet nozzle, and the application timing is not particularly limited. When the other liquid contains a colorant, a method of discharging with an inkjet nozzle is preferable, and it is preferable to apply after applying the primer ink.

  Here, the ink jet recording method will be described.

  In the present invention, for example, an electrostatic attraction method that ejects ink liquid using electrostatic force, a drop-on-demand system (pressure pulse system) that uses the vibration pressure of a piezo element, and an ink liquid that changes an electrical signal into an acoustic beam. Well-known methods such as an acoustic ink jet method in which an ink liquid is ejected by irradiating the ink with a radiation pressure and a thermal ink jet method in which the ink liquid is heated to form bubbles and the generated pressure is used are suitable. Inkjet recording methods include a method of ejecting a large number of ink liquids having a low optical density called photo ink in a small volume, a system for improving image quality using a plurality of ink liquids having substantially the same hue and different optical densities, A method using a colorless and transparent ink liquid is included.

  In the present invention, the ink droplets for image formation ejected on the primer ink are ejected with a droplet size of 0.1 pL (picoliter; the same applies hereinafter) to 100 pL (preferably by an inkjet nozzle). Is preferred. When the droplet size is within the above range, it is effective in that an image with high sharpness can be drawn while adjusting the optical density. More preferably, it is 0.5 pL or more and 50 pL or less.

  Further, the applied amount (mass ratio per unit area) of the primer ink is preferably within a range of 0.05 to 5 when the amount of ink droplets for image formation is 1, and preferably 0.07 to 4. Within the range is more preferable, and within the range of 0.1 to 3 is particularly preferable.

  The thickness of the primer layer formed by applying the primer ink on the recording medium and the undercoat layer obtained by curing the primer layer is preferably 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less, and more preferably 3 μm or more. More preferably, it is 8 μm or less. It is preferable that the thickness of the primer layer and the undercoat layer is within the above range since the flexibility and adhesion of the cured image can be satisfactorily maintained.

  It is preferable that the droplet ejection interval between the application of the primer ink and the ejection of the image forming ink and the primer ink is in the range of 5 μs or more and 10 seconds or less. It is effective in that the effect of the present invention can be remarkably exhibited when the droplet ejection interval is within the above range. The droplet ejection interval of the image forming ink composition droplets is more preferably 10 μs to 5 seconds, and particularly preferably 20 μs to 5 seconds.

  From the viewpoint of ensuring a better effect by using the primer ink of the present invention, the recording medium having no permeability is particularly preferable. Specifically, OPP (Oriented Polypropylene Film), CPP (Casted Polypropylene Film), PE (Polyethylene terephthalate), PET (Polyethylene terephthalate), PP (Polypropylene), metal sheet, laminate, low permeability A good image can be formed when paper or art paper is used.

  Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples. In addition, unless otherwise indicated, in the following, “part” means “part by mass”.

  Table 1 summarizes the materials used for the image forming ink composition in the following Examples and Comparative Examples. “Part” in Table 1 means “part by mass”.

  Table 2 summarizes the materials used for the energy ray curable primer ink in the following Examples and Comparative Examples. “Part” in Table 2 means “part by mass”.

The following two types of non-permeable media were used as recording media.
(1) Synthetic paper: “YUPO 80 PA-T1” manufactured by Lintec
(2) Polyester synthetic paper (biaxially stretched film): “Chrisper K1711” manufactured by Toyobo

  Next, Table 3 shows each component constituting the image forming ink composition used in the following Examples and Comparative Examples, and its blending amount. Tables 4 and 5 show the components constituting the primer ink compositions used in the following Examples and Comparative Examples, and their blending amounts. In Table 3, Table 4 and Table 5, “part” means “part by mass”.

  Tables 3 to 5 also show the viscosity and surface tension of each ink. A method for measuring the viscosity and surface tension of the ink will be described below.

(viscosity)
The viscosity of the primer ink and the image forming ink composition was measured using a “R100 viscometer” manufactured by Toki Sangyo Co., Ltd. under the conditions of 25 ° C. and cone rotation speed of 10 rpm.

(surface tension)
The surface tension of the primer ink and the image forming ink composition was measured under the condition of 25 ° C. using a fully automatic equilibrium electro surface tension meter “ESB-V” manufactured by Kyowa Kagaku.

(Preparation of image forming ink composition)
The image forming ink compositions used in the following Examples and Comparative Examples were prepared as follows.

  First, weigh out the colorant, dispersant, and polymerizable compound shown in Table 3 in a plastic bottle in the amounts shown in Table 3, add 100 parts of 0.1 mm diameter zirconia beads to this, and paint this mixture. A primary dispersion was obtained by dispersing for 2 hours with a conditioner (manufactured by Toyo Seiki Co., Ltd.). Next, the photopolymerization initiator, the sensitizer, and the surface conditioner shown in Table 3 were added to the obtained primary dispersion in the amounts shown in Table 3, and the mixture was stirred with a magnetic stirrer for 30 minutes. After stirring, this mixture was subjected to suction filtration using a glass filter (manufactured by Kiriyama Seisakusho) to prepare inks P-1 to P-4 for image formation. The viscosity of these inks was 21.3 to 22.8 mPa · s, and the surface tension was 25.5 to 31.4 mN / m.

Example 1
Each component which comprises the primer ink composition shown in Example 1 of Table 4 was measured by the compounding quantity shown in Example 1 of Table 4, and it stirred for 30 minutes with the magnetic stirrer, and obtained the mixture. Then, the said mixture was suction-filtered using the glass filter (made by Kiriyama Seisakusho), and the primer ink of Example 1 was prepared.

  The primer ink of Example 1 is combined with each of the image forming ink compositions P-1 to P-4 described above and each of the two types of recording media described above, and the printed material preparation procedure described below is performed. The printed matter of Example 1 was obtained according to (1) to (4).

(1) Primer ink was ejected onto a recording medium using an inkjet recording apparatus equipped with a piezo-type inkjet nozzle to prepare a 100 mm × 100 mm primer ink solid print (primer layer). At this time, the thickness of the primer layer was 5 μm. The ink jet 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. The ink jet recording apparatus was driven at a driving frequency of 10 KHz so that ink could be ejected with a droplet size of about 7 pL and a resolution of 600 × 600 dpi.

(2) The primer layer was irradiated with ultraviolet rays using an ultraviolet LED “NLBU21W01-E2” manufactured by Nichia Corporation so that the total irradiation light amount was 300 mJ / cm ² . Thereby, the primer layer was cured to obtain an undercoat layer.

(3) On the undercoat layer, an image forming ink was ejected using an ink jet recording apparatus equipped with a piezo ink jet nozzle to produce an image forming ink solid print. The ink jet 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. The ink jet recording apparatus was driven at a driving frequency of 10 KHz so that ink could be ejected with a droplet size of about 7 pL and a resolution of 600 × 600 dpi.

(4) Using the metal halide lamp “M015-L312” manufactured by Eye Graphic Co., Ltd., the image-formed ink solid printed matter was irradiated with ultraviolet rays so that the total irradiation light amount was 100 mJ / cm ² . As a result, the solid image printed matter for image formation was cured to obtain a printed matter.

(Example 2) to (Example 12), (Comparative Example 1) to (Comparative Example 6)
Each component of the primer ink compositions shown in Examples 2 to 12 and Comparative Examples 1 to 6 in Tables 4 and 5 was measured with the blending amounts shown in Tables 4 and 5, and the same procedure as in Example 1 was performed. Primer inks of Examples 2 to 12 and Comparative Examples 1 to 6 were prepared. And the printed matter of Examples 2-12 and Comparative Examples 1-6 was obtained like Example 1 using the primer ink of Examples 2-12 and Comparative Examples 1-6.

(Examples 13 to 16)
Each component of the primer ink composition shown in Examples 13 to 16 in Table 4 was weighed with the blending amounts shown in Table 4, and primer inks of Examples 13 to 16 were prepared in the same manner as in Example 1 above. And the printed matter of Examples 13-16 was obtained similarly to the said Example 1 except having apply | coated the primer ink of Examples 13-16 on the to-be-recorded medium using bar coater # 6.

  About each said Examples 1-16 and Comparative Examples 1-6, the wettability of primer ink, the reliability of the recording medium after provision of primer ink, the wettability of ink for image formation, ink curability, and image adhesion Evaluated. The evaluation results are shown in Tables 6 and 7 for each evaluation. Table 6 shows the evaluation results of Examples 1 to 16, and Table 7 shows the evaluation results of Comparative Examples 1 to 6. As the image forming ink, each of the image forming ink compositions P-1 to P-4 shown in Table 3 was combined with the primer inks of Examples 1 to 16 and Comparative Examples 1 to 6, and printed matter. The results when using P-1 with the most significant difference in characteristics are listed as representatives.

  Here, an evaluation method for each of the above evaluations will be described.

(Primer ink wettability)
The wettability of the primer ink was evaluated by visually observing the ink repelling of the primer ink solid printed material prepared according to the above-described printed material manufacturing procedure (1). In Tables 6 and 7, the evaluation results are indicated by “A”, “B”, and “C”. Explaining the evaluation criteria, “A” indicates that ink repelling cannot be confirmed and wettability is good, and “B” indicates that ink repelling occurs slightly and the surface is slightly uneven and partially Indicates that the surface of the recording medium is exposed and the wettability is slightly poor. “C” indicates that the ink is frequently repelled, and the exposed surface of the recording medium surface is uneven. Many show that the wettability is poor.

(Reliability of recording medium after application of primer ink)
Regarding the reliability of the recording medium after applying the primer ink, first, the recording medium on which the undercoat layer was formed in accordance with the above-described printed matter preparation procedures (1) and (2) was cut into a 50 mm × 50 mm square and tested. A piece was obtained, and the test piece was placed on a flat plate with the printing surface facing upward, and the curled state was evaluated by visual observation. In Tables 6 and 7, the evaluation results are indicated by “A”, “B”, and “C”. Explaining the evaluation criteria, “A” indicates that no curling is observed at the four corners of the test piece, there is no problem in quality, and the reliability is excellent, and “B” indicates curling at the four corners of the test piece. However, the total of the raised parts at the four corners is less than 30 mm, indicating that the reliability is somewhat poor. “C” indicates the occurrence of curling at the four corners of the test piece. The total of the raised parts is 30 mm or more, indicating that the reliability is inferior.

(Wettability of image forming ink)
The wettability of the image forming ink was evaluated by visually observing the repelling of the ink of the image forming ink solid print prepared according to the above-described printed material preparation procedures (1) to (3). In Tables 6 and 7, the evaluation results are represented by “A”, “B”, and “C”. Explaining the evaluation criteria, “A” indicates that ink repelling cannot be confirmed and the wettability is good, and “B” indicates that ink repelling occurs slightly and the surface is slightly uneven and partially Indicates that the surface of the recording medium is exposed and the wettability is slightly poor. “C” indicates that the ink is frequently repelled, and the exposed surface of the recording medium surface is uneven. Many indicate that the wettability is poor.

(Ink curing)
The ink curability was evaluated by touching the printed matter (image) produced according to the above-described printed matter producing procedures (1) to (4) with a finger and visually observing whether the ink adheres to the finger. In Tables 6 and 7, the evaluation results are represented by “A”, “B”, and “C”. Explaining the evaluation criteria, “A” indicates that the ink does not adhere to the finger and the ink curability is excellent, and “B” indicates that the fingerprint remains on the image, but the finger has no ink. Almost no adhesion, indicating that the ink curability is good, “C” indicates that the portion traced with the finger is greatly dragged, the ink adheres to the finger, and the ink curability is poor. .

(Adhesion)
The adhesion of the image was evaluated according to “cross-cut test cellotape peeling” defined in Japanese Industrial Standard (JIS) K5600-5-6. In Tables 6 and 7, the evaluation results are indicated by “A”, “B”, and “C”. Explaining the evaluation criteria, when the number of places where peeling was observed was 10 or less with respect to 100 test squares, the adhesiveness was judged to be excellent and indicated by “A”, and the peeling places were 11 to 11. When it is 20, the adhesiveness is judged to be good and indicated as “B”, and when the number of peeled portions is 21 or more, the adhesiveness is judged as poor and indicated as “C”. .

  As apparent from Tables 6 and 7, in Examples 1 to 16, the wettability of the primer ink, the reliability of the recording medium after application of the primer ink, the wettability of the image forming ink, the ink curability, and the image Good results were obtained for any of the adhesive properties. However, in Example 11 containing the bifunctional monomer, when “Crisper K1711” was used as the recording medium, the wettability of the primer ink was slightly inferior to the other examples, and the recording medium was curled. The occurrence of was seen. From this, it was found that the polymerizable compound used in the primer ink of the present invention is preferably a compound composed only of a monofunctional monomer.

  On the other hand, Comparative Example 1 containing no monomer a was inferior in image adhesion. Further, Comparative Examples 2 and 3 in which the monomer b was less than 10% by mass also had poor image adhesion. In Comparative Examples 4 and 5 containing a trifunctional monomer and a hexafunctional monomer as the polymerizable compound, the reliability of the recording medium after application of the primer ink was inferior. In Comparative Example 6 in which the total amount of the monomer a and the monomer b was less than 25% by mass, the image adhesion was inferior.

Claims (8)

An ink set including an image forming ink and a transparent energy ray curable primer ink,
The transparent energy ray curable primer ink has a polymerizable compound that undergoes a polymerization reaction or a crosslinking reaction upon irradiation with energy rays, and a polymerization start for initiating and promoting the polymerization reaction or the crosslinking reaction of the polymerizable compound. Agent,
The polymerizable compound is
Monomer consisting of a monofunctional monomer only, or a monofunctional monomer and a bifunctional monomer, and having a (meth) acryl group and any one functional group of an oxetane group, an oxirane ring and a vinyl ether group in the molecule When,
2-hydroxy-3-phenoxypropyl acrylate,
The sum of the monomer and the 2-hydroxy-3-phenoxypropyl acrylate is 25 to 95% by mass with respect to the total amount of the ink,
The ink set characterized in that the content of the 2-hydroxy-3-phenoxypropyl acrylate is 10% by mass or more based on the total amount of the ink.   The ink set according to claim 1, wherein the polymerizable compound contains 2- (2-vinyloxyethoxy) ethyl (meth) acrylate as a monomer having a (meth) acryl group and a vinyl ether group.   The ink set according to claim 1, wherein the polymerizable compound further includes a monomer having only an acrylic group.   The ink set according to claim 1, wherein the transparent energy ray curable primer ink is for inkjet recording.   The transparent energy ray curable primer ink further includes at least one resin selected from the group consisting of acrylic resins, polyester resins, polyurethane resins, vinyl chloride resins, and nitrocellulose. The ink set according to any one of the above. A printing method using the ink set according to any one of claims 1 to 5,
Applying the transparent energy ray curable primer ink to a substrate and curing it to form a primer ink film;
And a step of applying and curing the image forming ink on the primer ink film.   The printing method according to claim 6, wherein the application of the transparent energy ray curable primer ink and the application of the image forming ink are performed by an inkjet method.   The printing method according to claim 7, wherein the application of the transparent energy ray curable primer ink and the application of the image forming ink are performed by a multi-pass method.