JP2005060519A - Ink-jet ink and printing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet ink high in sensitivity to various bases and excellent in adhesive strength, and to provide a printing method using the ink. <P>SOLUTION: The ink-jet ink, which is photopolymerizable, essentially comprises a coloring material, a polymerizable compound, a photopolymerization initiator and an inert resin. As the inert resin, an adhesive resin is included at 1-10 mass% of the whole ink. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inkjet ink containing a photopolymerizable composition that can be reacted and cured by irradiation with light rays such as visible light, ultraviolet light, infrared light, γ-ray, and electron beam, and a recording method using the same.

  In recent years, the ink jet recording system can create images easily and inexpensively, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters. In particular, a recording device that emits and controls fine dots, ink that has improved color reproduction gamut, durability, and emission suitability, and ink absorbability, coloring material color development, surface gloss, etc. have been dramatically improved. It is also possible to obtain image quality comparable to silver halide photography using special paper. The image quality improvement of today's ink jet recording system is achieved only when all of the recording apparatus, ink, and special paper are available.

  However, in an inkjet system that requires dedicated paper, the recording medium is limited, and the cost of the recording medium increases. Therefore, many attempts have been made to record on a transfer medium different from dedicated paper by an ink jet method. Specifically, a phase change ink jet method using a wax ink solid at room temperature, a solvent ink jet method using an ink mainly composed of a fast-drying organic solvent, a UV ink jet method in which crosslinking is performed by ultraviolet (UV) light after recording, etc. It is.

  Among them, the UV inkjet method has been attracting attention in recent years in that it has a relatively low odor compared to the solvent-based inkjet method and can be recorded on a recording medium having no quick drying and no ink absorption. No. 54667, JP-A-6-200204, and JP 2000-504778 disclose ultraviolet curable inkjet inks.

  However, although the ultraviolet curable ink jet recording method is characterized in that it can be recorded on various substrates, an appropriate dot diameter and a sufficient dot diameter are sufficient for all types of substrates with one ink composition. It is very difficult to give adhesion. In particular, it is difficult to obtain sufficient adhesion to an olefin-based substrate.

  As a method for improving the adhesion between the ink and the substrate in the ink jet recording method, it is described that a specific resin is used as the ink composition (for example, see Patent Documents 1 and 2). However, in these known examples, even if the ink to be used is a phase change type or a photopolymerizable type, specific conditions for improving adhesion, a preferable blending example, or a preferable recording method will be described. No disclosure has been made. In particular, there are concerns that adhesive and tacky resins may cause problems such as reduced reactivity and impaired injection stability with increased ink viscosity depending on the type of application. Not done.

In general, there are radical polymerization type and cationic polymerization type as ultraviolet curable ink-jet ink, but the cationic polymerization type is not subject to polymerization inhibition of oxygen, and ionic polymerizable monomers such as oxetane and epoxy have a small odor, There are advantages such as low cure shrinkage, and attention has been paid. Various ultraviolet curable ink-jet inks using cationically polymerizable compounds have been proposed (see, for example, Patent Documents 3 to 7). The ink jet ink has a problem that the adhesion to various substrates is not sufficient, and further improvement is required. In particular, there is no disclosure regarding a preferred ink composition or a preferred recording method as means for improving the adhesion to the substrate.
JP 2001-207098 A (paragraph numbers 0035 to 0036) JP 2001-288386 A (paragraph number 0030) JP 2001-220526 A (Claims, Examples) JP 2002-188025 A (Claims, Examples) JP 2002-317139 A (Claims, Examples) JP 2003-55449 A (Claims, Examples) JP 2003-73481 A (Claims, Examples)

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet ink that is highly sensitive to various substrates and excellent in adhesion strength, and a recording method using the same.

The above object of the present invention is achieved by the following configurations.
(Claim 1)
In a photopolymerizable inkjet ink containing at least a colorant, a polymerizable compound, a photopolymerization initiator, and a non-reactive resin, an adhesive or tacky resin is used as the non-reactive resin for 1 to 10 of the entire ink. An ink-jet ink comprising: mass%.
(Claim 2)
The inkjet ink according to claim 1, wherein the adhesive or tacky resin is a tackifier having a softening point of 120 ° C. or lower.
(Claim 3)
The polymerizable compound is at least one selected from a cationic polymerizable epoxy compound, an oxetane compound, and a vinyl ether compound, and the photopolymerization initiator is a photoacid generator. 2. An ink-jet ink as described in 2.
(Claim 4)
The ink-jet ink according to any one of claims 1 to 3, wherein the viscosity at 50 ° C is 20 mPa · s or less.
(Claim 5)
An inkjet recording method for curing an image by irradiating with light after ejecting the inkjet ink according to any one of claims 1 to 4 from an inkjet nozzle onto a substrate, wherein the inkjet ink is used at the time of ejection. A recording method, wherein the ink droplet size is 4 to 40 pl.
(Claim 6)
6. The recording method according to claim 5, wherein the ink jet ink landed on the substrate is subjected to a heat treatment at the time of light irradiation or after light irradiation.

  According to the present invention, it is possible to provide an ink-jet ink that is highly sensitive to various substrates, has excellent adhesion strength and injection stability, and a recording method using the same.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  The inkjet ink of the present invention (hereinafter also simply referred to as ink) contains at least a colorant, a polymerizable compound, a photopolymerization initiator, and a non-reactive resin, and the non-reactive resin is adhesive or tacky. 1 to 10% by mass of the total amount of the ink.

  First, details of the non-reactive resin according to the present invention will be described.

  The non-reactive resin according to the present invention is intended to improve the adhesion of an inkjet ink to a substrate and to impart scratch resistance to printed matter, and is a polymerizable compound contained in an inkjet ink. Examples thereof include thermosetting or thermoplastic resins that are soluble in monomers or oligomers.

  Examples of the non-reactive resin according to the present invention include polyvinyl chloride, poly (meth) acrylic ester, epoxy resin, polyurethane resin, cellulose derivatives (for example, ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride-vinyl acetate. Copolymer, polyamide resin, polyvinyl acetal resin, diallyl phthalate resin, butadiene-acrylonitrile copolymer, acrylic resin, styrene-acrylic resin, styrene-maleic acid resin, rosin resin, rosin ester resin, ethylene -Vinyl acetate resin, petroleum resin, coumarone indene resin, terpene phenol resin, phenol resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, vinyl chloride resin, xylene resin, alkyd Resin, aliphatic hydrocarbon tree , Butyral resins, silicone resins, maleic acid resins and fumaric acid resins.

  The non-reactive resin is roughly classified into a tacky resin (tackifier) and an adhesive resin.

  The tackifier is a thermosetting or thermoplastic resin belonging to an amorphous oligomer having a molecular weight of several hundred to several thousand. Among the above resins, rosin ester resin, polymerized rosin resin, disproportionated rosin Resin, aliphatic (C5) petroleum resin, aromatic (C9) petroleum resin, aliphatic (C9 hydrogenated) petroleum resin, aliphatic (DCPD) petroleum resin, coumarone / indene resin, Examples thereof include hydrogenated terpene resins, terpene phenol resins, styrene resins, substituted styrene resins, phenol resins, and maleic acid resins. Examples of the adhesive resin include acid-modified polyolefin resins, ionomer resins, ethylene-acrylic acid copolymer resins, and metal salts thereof.

  The adhesive resin can be used even if it is dispersed in water like latex. Moreover, it is also possible to use two or more types of the above-mentioned compounds as an adhesive compound. The resin is preferably fused by heating the recording medium, and the temperature required for the fusion is preferably 30 to 120 ° C, more preferably 30 to 80 ° C.

  In the inkjet ink of the present invention, the adhesion to the substrate can be improved by adding 1 to 10% by mass of a non-reactive adhesive or tacky resin. If the content of the non-reactive adhesive or tacky resin is less than 1% by mass, the desired effect cannot be obtained, and if it exceeds 10% by mass, the viscosity of the ink increases and stable emission cannot be obtained. More preferably, it is 1-5 mass%.

  Moreover, in the ink for inkjet of this invention, it is preferable that adhesive resin or adhesive resin is a tackifier with a softening point of 120 degrees C or less, More preferably, it is 100 degrees C or less. When the softening point is higher than 120 ° C., sufficient adhesion improving effect cannot be obtained. Moreover, it is preferable that a softening point is 120 degrees C or less also from the point of the viscosity at the time of melt | dissolving in an ink.

  Next, each component of the inkjet ink of the present invention will be described.

  The ink-jet ink of the present invention contains at least a coloring material, a polymerizable compound, and a photopolymerization initiator in addition to the non-reactive resin.

(Photopolymerizable compound)
One of the polymerizable compounds that can be used in the present invention is a radical polymerizable compound. For example, JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, and JP-A-10-863. No., Japanese Patent Application No. 7-231444, and the like.

  The radical polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and may be any compound as long as it has at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. , Oligomers, polymers and the like having chemical forms. Only one type of radically polymerizable compound may be used, or two or more types thereof may be used in combination at an arbitrary ratio in order to improve desired properties.

  Examples of compounds having an ethylenically unsaturated bond capable of radical polymerization include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid and their salts, esters, urethanes, amides. And radically polymerizable compounds such as various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides and unsaturated urethanes. Specifically, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol Diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol Tetraacrylate, dipentaery Acrylic acid derivatives such as lithol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, N-methylol acrylamide, diacetone acrylamide, epoxy acrylate, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate , Lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylol Methacryl derivatives such as tan trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate More specifically, Shinzo Yamashita, “Cross-linking agent handbook”, (1981 Taiseisha); Kato Kiyomi, “UV / EB curing handbook (raw material)” (1985, Polymer publication) ); Rad-Tech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products described in the above, or radically polymerizable or crosslinkable monomers known in the industry, Oligomers and polymers can be used.

  The addition amount of the radical polymerizable compound is preferably 1 to 97% by mass, and more preferably 30 to 95% by mass with respect to the ink composition.

  In the present invention, a cationic polymerizable compound is preferably used as one of the polymerizable compounds, and is preferably at least one selected from a cationic polymerizable epoxy compound, an oxetane compound, and a vinyl ether compound. Among them, it is preferable to use an oxetane compound and an epoxy compound in combination in order to obtain a highly reactive and low-viscosity ink. The mass ratio of the oxetane compound and the epoxy compound is preferably 90:10 to 30:70, preferably 85: 15-50: 50.

  Various known cationic polymerizable monomers can be used as the cationic polymerizable monomer. For example, the epoxies exemplified in JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, JP-A-2001-220526 Compounds, vinyl ether compounds, oxetane compounds and the like.

  A preferable aromatic epoxide is a di- or polyglycidyl ether produced by the reaction of a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof and epichlorohydrin, such as bisphenol A or an alkylene oxide thereof. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or alkylene oxide adducts thereof, and novolak type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  The alicyclic epoxide can be obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Cyclohexene oxide or cyclopentene oxide-containing compounds are preferred.

  Preferred aliphatic epoxides include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or Diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or its alkylene oxide adduct, polyethylene glycol or its alkylene oxide adduct Of polyalkylene glycols such as diglycidyl ether, polypropylene glycol or diglycidyl ether of its alkylene oxide adduct Glycidyl ether, and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  Among these epoxides, in view of fast curability, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable. In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

  Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -o- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

  Among these vinyl ether compounds, in consideration of curability, adhesion, and surface hardness, di- or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable. In the present invention, one of the above vinyl ether compounds may be used alone, or two or more thereof may be used in appropriate combination.

  In the present invention, it is preferable to contain at least one oxetane compound as a photopolymerizable compound for the purpose of suppressing shrinkage of the substrate during ink curing.

  The oxetane compound according to the present invention is a compound having an oxetane ring, and any known oxetane compound as introduced in JP-A Nos. 2001-220526 and 2001-310937 can be used.

  In the oxetane compound according to the present invention, when a compound having 5 or more oxetane rings is used, the viscosity of the ink composition becomes high, so that handling becomes difficult, and the glass transition temperature of the ink composition becomes high. The resulting cured product will not be sufficiently sticky. The compound having an oxetane ring used in the present invention is preferably a compound having 1 to 4 oxetane rings.

  Hereinafter, although the specific example of the compound which has an oxetane ring based on this invention is demonstrated, this invention is not limited to these.

  An example of the compound having one oxetane ring is a compound represented by the following general formula (1).

In the general formula (1), R ¹ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, or an aryl group. , Furyl group or thienyl group. R ² is an alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl- C2-C6 alkenyl group such as 2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group, phenoxyethyl group, etc. A group having an aromatic ring, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethylcarbonyl group, a propylcarbonyl group, and a butylcarbonyl group, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethoxycarbonyl group, a propoxycarbonyl group, and a butoxycarbonyl group; Alkoxycarbonyl group, ethylcarbamoyl group, propylcarbamoyl group, butylcarbamoyl group, pentylcarbamoyl Is N- alkylcarbamoyl group having a carbon number of 2-6 and the like. As the oxetane compound used in the present invention, it is particularly preferable to use a compound having one oxetane ring because the resulting composition has excellent tackiness, low viscosity and excellent workability.

  An example of a compound having two oxetane rings includes a compound represented by the following general formula (2).

In the general formula (2), R ¹ is the same group as that in the general formula (1). R ³ is, for example, a linear or branched alkylene group such as an ethylene group, a propylene group or a butylene group, a linear or branched poly (alkyleneoxy) such as a poly (ethyleneoxy) group or a poly (propyleneoxy) group. ) Group, propenylene group, methylpropenylene group, butenylene group or other linear or branched unsaturated hydrocarbon group, alkylene group containing carbonyl group or carbonyl group, alkylene group containing carboxyl group, alkylene containing carbamoyl group Group.

Moreover, as R < ³ >, the polyvalent group selected from the group shown by the following general formula (3), (4) and (5) can also be mentioned.

In the general formula (3), R ⁴ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. An alkoxy group having 1 to 4 carbon atoms, a halogen atom such as a chlorine atom or a bromine atom, a nitro group, a cyano group, a mercapto group, a lower alkoxycarbonyl group, a carboxyl group, or a carbamoyl group.

In the general formula (4), R ⁵ represents an oxygen atom, a sulfur atom, a methylene group, NH, SO, SO ₂ , C (CF ₃ ) ₂ , or C (CH ₃ ) ₂ .

In General formula (5), R < ⁶ > is a C1-C4 alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, or an aryl group. n is an integer of 0-2000. R ⁷ is a methyl group, an ethyl group, a propyl group, a butyl group having 1 to 4 carbon atoms, or an aryl group. R ⁷ may further include a group selected from the group represented by the following general formula (6).

In General formula (6), R < ⁸ > is a C1-C4 alkyl group, such as a methyl group, an ethyl group, a propyl group, a butyl group, or an aryl group. m is an integer of 0-100.

  Specific examples of the compound having two oxetane rings include the following compounds.

Illustrative compound 1 is a compound in which R ¹ is an ethyl group and R ³ is a carboxyl group in the general formula (2). Exemplary compound 2 is a compound in which, in the general formula (2), R ¹ is an ethyl group, R ³ is the general formula (5), R ⁶ and R ⁷ are methyl groups, and n is 1.

Among the compounds having two oxetane rings, preferred examples other than the above compounds include compounds represented by the following general formula (7). In general formula (7), R ¹ has the same meaning as R ¹ in the general formula (1).

  An example of a compound having 3 to 4 oxetane rings is a compound represented by the following general formula (8).

In the general formula (8), R ¹ is the same meaning as R ¹ in the general formula (1). As R ⁹ , for example, a branched alkylene group having 1 to 12 carbon atoms such as groups represented by the following A to C, a branched poly (alkyleneoxy) group such as a group represented by the following D, or the following E And branched polysiloxy groups such as those shown. j is 3 or 4.

In A above, R ¹⁰ is a lower alkyl group such as a methyl group, an ethyl group or a propyl group. Moreover, in said D, p is an integer of 1-10.

  Illustrative compound 3 is an example of a compound having 3 to 4 oxetane rings.

  Furthermore, examples of the compound having 1 to 4 oxetane rings other than those described above include compounds represented by the following general formula (9).

In the general formula (9), R ⁸ has the same meaning as R ⁸ in the general formula (6). R ¹¹ is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, or a trialkylsilyl group, and r is 1 to 4.

  Preferable specific examples of the oxetane compound used in the present invention include the following compounds.

  The method for producing each compound having an oxetane ring described above is not particularly limited, and may be a conventionally known method, for example, Pattisson (DB Pattison, J. Am. Chem. Soc., 3455, 79). (1957)) discloses a method for synthesizing an oxetane ring from a diol. In addition to these, compounds having 1 to 4 oxetane rings having a high molecular weight of about 1000 to 5000 are also included. Examples of these specific compounds include the following compounds.

  As the photopolymerizable compound according to the present invention, any of the radically polymerizable compound and the thiopolymerizable compound described above can be used. However, even if the irradiation intensity (mW) of ultraviolet rays is changed, the curing sensitivity hardly changes. That is, a compound having a small illuminance failure is preferable. In this respect, a cationic polymerizable compound is more preferable than a radical polymerizable compound that is inhibited by oxygen. In particular, in an ink jet recording system having a small ink droplet size, a cation polymerizable compound is more preferable than a radical polymerizable compound in terms of curability at small points.

In the present invention, the inkjet ink contains a photopolymerization initiator. In the present invention, in order to perform the curing reaction more efficiently, it is preferable to add a known photopolymerization initiator and cure. Photopolymerization initiators can be broadly classified into two types: intramolecular bond cleavage type and intramolecular hydrogen abstraction type.

  Examples of the intramolecular bond cleavage type photopolymerization initiator include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2. -Hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4 Acetophenones such as -thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone; benzoins such as benzoin, benzoin methyl ether, benzoin isopropyl ether; 2 , 4,6-Trimethylbenzoindiphenyl Scan fins oxides such acylphosphine oxide of benzil, methyl phenylglyoxylate esters.

  On the other hand, as an intramolecular hydrogen abstraction type photopolymerization initiator, for example, benzophenone, methyl 4-phenylbenzophenone, o-benzoylbenzoate, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl Benzophenones such as diphenyl sulfide, acrylated benzophenone, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 3,3'-dimethyl-4-methoxybenzophenone; 2-isopropylthioxanthone, 2 Thioxanthone series such as 1,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone; amino benzophenone series such as Michler-ketone, 4,4'-diethylaminobenzophenone; 10-butyl- - chloro acridone, 2-ethyl anthraquinone, 9,10-phenanthrenequinone, camphorquinone, and the like. The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 10.00% by mass of the actinic ray curable composition.

  In the inkjet ink of the present invention, it is preferable to use a photoacid generator as a photopolymerization initiator.

  Examples of the photoacid generator that is a photopolymerization initiator that can be used in the present invention include all known photoacid generators.

  As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), 187. To page 192). Examples of compounds suitable for the present invention are listed below.

First, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium, etc. be able to.

  Specific examples of onium compounds that can be used in the present invention are shown below.

  Secondly, sulfonated substances that generate sulfonic acid can be mentioned, and specific compounds thereof are exemplified below.

  Thirdly, halides that generate hydrogen halide can also be used, and specific compounds thereof are exemplified below.

  Fourthly, an iron allene complex can be mentioned.

  The ink according to the present invention includes, for the first time, JP-A-8-248561 and JP-A-9-34106, and an acid proliferating agent that newly generates an acid by an acid generated by actinic ray irradiation that has already been known. It is preferable to do. By using an acid multiplication agent, it is possible to further improve discharge stability.

  Moreover, although the inkjet ink of the present invention is cured by irradiation with ultraviolet rays, a photosensitizer can be used in combination in order to perform the curing reaction more efficiently. Examples of such a photosensitizer include triethanolamine, methyldiethanolamine, triisopropanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, benzoic acid ( 2-dimethylamino) ethyl, 4-dimethylaminobenzoic acid (n-butoxy) ethyl, amines such as 4-dimethylaminobenzoic acid 2-ethylhexyl, cyanine, phthalocyanine, merocyanine, porphyrin, spiro compound, ferrocene, fluorene, fulgide Imidazole, perylene, phenazine, phenothiazine, polyene, azo compound, diphenylmethane, triphenylmethane, polymethine acridine, coumarin, ketocoumarin, quinacridone, indigo, styryl, pyriri Compounds, pyromethene compounds, pyrazolotriazole compounds, benzothiazole compounds, barbituric acid derivatives, thiobarbituric acid derivatives, and the like, and further, European Patent No. 568,993, US Patent No. 4,508,811, The compounds described in JP-A-5,227,227, JP-A-2001-125255, JP-A-11-271969 and the like can also be used. The usage-amount of a photosensitizer has the preferable range of 0.01-10.00 mass% in actinic-light curable composition.

  In the inkjet ink of the present invention, various colorants that can be dissolved or dispersed in the main component of the polymerizable compound can be used as the colorant, but pigments are preferred from the viewpoint of weather resistance.

  As a pigment that can be used in the inkjet ink of the present invention, an achromatic inorganic pigment such as carbon black, titanium oxide, calcium carbonate, or a chromatic organic pigment can be used. Examples of organic pigments include, for example, insoluble azo pigments such as toluidine red, toluidine maroon, Hansa yellow, benzidine yellow, and pyrazolone red, soluble azo pigments such as lithol red, helio bordeaux, pigment scarlet, and permanent red 2B, alizarin, and indanthrone. Derivatives from vat dyes such as thioindigo maroon, phthalocyanine organic pigments such as phthalocyanine blue and phthalocyanine green, quinacridone organic pigments such as quinacridone red and quinacridone magenta, perylene organic pigments such as perylene red and perylene scarlet, Isoindolinone organic pigments such as indolinone yellow and isoindolinone orange, and pyranthrone systems such as pyranthrone red and pyranthrone orange Pigments, thioindigo organic pigments, condensed azo organic pigments, benzimidazolone organic pigments, quinophthalone organic pigments such as quinophthalone yellow, isoindoline organic pigments such as isoindoline yellow, and other pigments such as flavanthrone yellow, acyl Examples include amide yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianslaquinonyl red, and dioxazine violet.

  When organic pigments are exemplified by color index (CI) numbers, C.I. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 109, 110, 117, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, C.I. I. Pigment orange 16, 36, 43, 51, 55, 59, 61, C.I. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 146, 149, 168, 177, 180, 192, 202, 206, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, C.I. I. Pigment violet 19, 23, 29, 30, 37, 40, 50, C.I. I. Pigment blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64, C.I. I. Pigment green 7, 36, C.I. I. Pigment brown 23, 25, 26, and the like.

  Among the above pigments, quinacridone organic pigments, phthalocyanine organic pigments, benzimidazolone organic pigments, isoindolinone organic pigments, condensed azo organic pigments, quinophthalone organic pigments, isoindoline organic pigments, etc. are light-resistant. Is preferable because it is excellent.

  For the dispersion of the pigment, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like can be used. Further, a dispersing agent can be added when dispersing the pigment. As the dispersant, a polymer dispersant is preferably used. Examples of the polymer dispersant include Avecia's Solsperse series and Ajinomoto Fine-Techno's PB series. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. The dispersion medium is used using a solvent or a polymerizable compound. However, the radiation curable ink of the present invention is preferably solvent-free because it reacts and cures immediately after ink landing. If the solvent remains in the cured image, the solvent resistance deteriorates and the VOC of the remaining solvent arises. Therefore, it is preferable in view of dispersibility that the dispersion medium is not a solvent but a polymerizable compound, and among them, a monomer having the lowest viscosity is selected.

  The pigment is preferably dispersed so that the average particle size of the pigment particles is 0.08 to 0.5 μm, and the maximum particle size is 0.1 to 5 μm, preferably 0.1 to 2 μm. It is preferable to appropriately set the selection of the dispersion medium, the dispersion conditions, and the filtration conditions. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained. In the ink of the present invention, the color material concentration is preferably 1% by mass to 10% by mass of the whole ink.

  Various additives other than those described above can be used in the ink of the present invention. For example, a leveling additive and a matting agent can be added. In addition, for the purpose of improving storage stability, any known basic compound can be used, but representative examples include basic organic compounds such as basic alkali metal compounds, basic alkaline earth metal compounds, and amines. Compounds and the like. It is also possible to combine a radically polymerizable monomer and an initiator into a radical / cation hybrid type curable ink.

  The ink of the present invention preferably has a viscosity at 50 ° C. of 20 mPa · s or less, more preferably 5 to 20 mPa · s, in order to obtain stable light emission. In order to obtain a low viscosity, the amount ratio of the adhesive or tacky resin to the whole ink is 10% by mass or less, more preferably 5% by mass or less, and the amount ratio of the oxetane compound part of the polymerizable monomer is 30% by mass. As mentioned above, More preferably, it is 50 mass% or more.

  As the base material that can be used in the recording method of the present invention, various non-absorbable plastics and films used for so-called flexible packaging can be used in addition to ordinary uncoated paper, coated paper, etc. Examples of the film include polyethylene terephthalate (PET) film, stretched polystyrene (OPS) film, stretched polypropylene (OPP) film, stretched nylon (ONy) film, polyvinyl chloride (PVC) film, polyethylene (PE) film, triacetyl A cellulose (TAC) film etc. can be mentioned. As other plastics, polycarbonate, acrylic resin, ABS, polyacetal, polyvinyl alcohol (PVA), rubbers and the like can be used. Moreover, it is applicable also to metals and glass. Among these substrates, the structure of the present invention is effective particularly when an image is formed on a PET film, an OPS film, an OPP film, an ONy film, or a PVC film that can be shrunk by heat. These substrates are not only susceptible to curling and deformation of the film due to ink curing shrinkage and heat generation during the curing reaction, but also the ink film is difficult to follow the substrate shrinkage.

  The surface energies of these various plastic films differ greatly, and it has been a problem in the past that the dot diameter after ink landing varies depending on the substrate. With the configuration of the present invention, good high-definition images can be formed on a wide range of substrates with a surface energy of 35 to 60 mN / m, including OPP films with low surface energy, OPS films, and PET with relatively high surface energy. it can.

  Next, the recording method of the present invention will be described.

  In the recording method of the present invention, as described above, the above ink is ejected and drawn on a substrate by an inkjet recording method, and then within 1.0 second, 0.05 seconds or more and 5.0 seconds or less. It is preferable to cure the ink by irradiating actinic rays such as ultraviolet rays.

  In the present invention, the ink film thickness after the ink has landed on the substrate and irradiated and cured with actinic rays is preferably 2 to 40 μm, more preferably 2 to 20 μm. In the actinic ray curable inkjet recording in the screen printing field, the ink film thickness currently exceeds 20 μm, but in the flexible packaging printing field where the base material is often a thin plastic material, In addition to the problem of curling and wrinkles, there is a problem that the entire printed matter is changed in its texture and texture, so that it is not preferable to eject ink with an excessive film thickness.

  Here, “ink film thickness” means the maximum value of the film thickness of the ink drawn on the base material, and it is a single color or other two-color superposition (secondary color), three-color superposition, and four-color superposition. Even when recording is performed by the (white ink base) inkjet recording method, the meaning of the ink film thickness is the same.

  As the ink discharge conditions, it is preferable from the viewpoint of discharge stability that the ink jet recording head and the ink are heated to 35 to 100 ° C. and discharged. UV curable ink has a large viscosity fluctuation range due to temperature fluctuation, and the viscosity fluctuation directly affects the droplet size and droplet ejection speed, causing image quality degradation, so keep the temperature constant while raising the ink temperature. It is necessary. The control range of the ink temperature is set temperature ± 5 ° C., preferably set temperature ± 2 ° C., more preferably set temperature ± 1 ° C.

  Moreover, in this invention, in order to acquire adhesiveness with various base materials, it is preferable to make it discharge | emit and harden | cure a droplet size with 4-40 pl and a small size. More preferably, it is 4-20pl.

  The smaller the droplet, the more difficult it is to completely cure the UV curable ink. This is because the radical polymerization type ink is affected by oxygen, and the cationic polymerization type ink is affected by moisture in the air and the substrate. As means for solving these problems, radical polymerization is effective in reducing oxygen concentration by purging with nitrogen, etc., and cationic polymerization is effective in dehumidification and / or dehydration or heating of the substrate.

  A basic method of actinic ray irradiation is disclosed in JP-A-60-132767. According to this, the light source is provided on both sides of the head unit, and the head and the light source are scanned by the shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In US Pat. No. 6,145,979, as an irradiation method, a method using an optical fiber or a method of applying a collimated light source to a mirror surface provided on the side of the head unit and irradiating the recording unit with UV light is disclosed. Yes. Any of these irradiation methods can be used in the image forming method according to the present invention.

  Next, an ink jet recording apparatus (hereinafter simply referred to as a recording apparatus) that can be used in the present invention will be described.

  Hereinafter, a recording apparatus according to the present invention will be described with reference to the drawings as appropriate. Note that the recording apparatus in the drawings is only one aspect of the recording apparatus that can be preferably used in the present invention, and the present invention is not limited to the drawing of the recording apparatus exemplified here.

  FIG. 1 is a front view showing an example of a configuration of a main part used in a serial printing method in an ink jet recording apparatus that can be used in the present invention. The recording apparatus 1 includes a head carriage 2, a recording head 3, an irradiation unit 4, a platen unit 5, and the like. In the recording apparatus 1, the platen unit 5 is installed under the base material P. The platen unit 5 has a function of absorbing ultraviolet rays, and absorbs excess ultraviolet rays that have passed through the substrate P. As a result, a high-definition image can be reproduced very stably.

  The base material P is guided by the guide member 6 and moves from the near side to the far side in FIG. 1 by the operation of the conveying means (not shown). A head scanning unit (not shown) scans the recording head 3 held by the head carriage 2 by reciprocating the head carriage 2 in the Y direction in FIG.

  The head carriage 2 is installed on the upper side of the substrate P, and stores a plurality of recording heads 3 to be described later according to the number of colors used for image printing on the substrate P, with the discharge ports arranged on the lower side. The head carriage 2 is installed with respect to the main body of the recording apparatus 1 in such a manner that it can reciprocate in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by driving the head scanning means.

  In FIG. 1, the head carriage 2 is illustrated as accommodating the recording heads 3 of yellow (Y), magenta (M), cyan (C), and black (K). The number of colors of the recording head 3 housed in the head carriage 2 can be determined as appropriate.

  The recording head 3 is operated by a discharge means (not shown) provided with a plurality of actinic ray curable inks (for example, UV curable ink) supplied by an ink supply means (not shown). It discharges toward the base material P from a discharge outlet. The UV ink ejected by the recording head 3 is composed of a coloring material, a polymerizable monomer, an initiator, and the like, and the monomer crosslinks when the initiator acts as a catalyst when irradiated with ultraviolet rays. It has the property of being cured by a polymerization reaction.

  The recording head 3 has a certain region (landing possible region) on the substrate P during scanning of moving from one end of the substrate P to the other end of the substrate P in the Y direction in FIG. ), UV ink is ejected as ink droplets, and ink droplets are landed on the landable area.

  The above scanning is performed as many times as necessary, and after UV ink is ejected toward one landable area, the substrate P is appropriately moved from the front to the back in FIG. 1 by the conveying means, and scanning by the head scanning means is performed again. 1, the recording head 3 discharges UV ink to the next landable area adjacent in the depth direction in FIG.

  By repeating the above-described operation and discharging the UV ink from the recording head 3 in conjunction with the head scanning unit and the conveying unit, an image composed of an aggregate of UV ink droplets is formed on the substrate P.

  The irradiation unit 4 includes an ultraviolet lamp that emits ultraviolet light in a specific wavelength region with stable exposure energy and a filter that transmits ultraviolet light of a specific wavelength. Here, as the ultraviolet lamp, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a hot cathode tube, a cold cathode tube, a black light, an LED (light emitting diode), etc. can be applied. Cathode tubes, mercury lamps or black lights are preferred.

  The irradiating means 4 has substantially the same shape as the maximum one that can be set by the recording apparatus (UV inkjet printer) 1 among the landable areas in which the recording head 3 ejects UV ink by one scan driven by the head scanning means. , Having a shape larger than the landable area.

  The irradiating means 4 is fixed on both sides of the head carriage 2 so as to be substantially parallel to the substrate P.

  As described above, as means for adjusting the illuminance of the ink discharge portion, not only the entire recording head 3 is shielded, but in addition, the ink discharge of the recording head 3 is determined from the distance h1 between the irradiation means 4 and the substrate P. It is effective to increase the distance h2 between the portion 31 and the substrate P (h1 <h2), or to increase the distance d between the recording head 3 and the irradiation means 4 (d is increased). Further, it is more preferable to provide a bellows structure 7 between the recording head 3 and the irradiation means 4.

  Here, the wavelength of the ultraviolet rays irradiated by the irradiation means 4 can be changed as appropriate by replacing the ultraviolet lamp or filter provided in the irradiation means 4.

  In the recording method of the present invention, it is preferable to heat-treat the ink-jet ink landed on the substrate at the time of light irradiation or after light irradiation.

  As the heating means, a method using a heat plate that guides the conveyance of the substrate and generates heat is preferable. Heat is transmitted to the substrate from the heat plate that conveys and guides the substrate, and the ink jet ink landed by this heat is heated. Is done.

  It is also preferable that the heating means is a hot air blowing means for blowing hot air onto the ink jet ink landed on the substrate.

  The heating temperature of the ink jet ink landed on the substrate is preferably 40 to 80 ° C. If the heating temperature is lower than 40 ° C., the landed ink is not cured depending on the environmental humidity, and the image quality is impaired. If the temperature is higher than 80 ° C., the film base material is shrunk and wrinkled, which is not preferable.

Example 1
<Preparation of inkjet ink>
[Preparation of Ink 1]
Cationic polymerizable compound (oxetane compound Aron oxetane OXT221 manufactured by Toagosei Co., Ltd.) 70 parts by mass Cationic polymerizable compound (epoxy compound epoxidized vegetable oil Sansosizer E4030 Shin Nippon Rika Co., Ltd.) 30 parts by mass Photopolymerization initiator (SP152 triarylsulfonium salt Active ingredient 50% Asahi Denka Co., Ltd.) 5 parts by weight Pigment (CI pigment Blue 15: 4) 4 parts by weight Dispersant (PB822, manufactured by Ajinomoto Fine Techno Co., Ltd.) 0.8 parts by weight The above dispersant (PB822 Ajinomoto Fine Techno) 0.8 parts by mass and the above cationically polymerizable compound were placed in a stainless beaker and stirred and mixed for 1 hour while being heated on a hot plate at 65 ° C. to dissolve. Next, after adding a pigment to this solution, it was sealed in a plastic bottle together with 200 g of zirconia beads having a diameter of 1 mm, and subjected to a dispersion treatment with a paint shaker for 2 hours. Next, zirconia beads were removed, a photoacid generator was added, and this was filtered through a 0.8 μm membrane filter to prevent clogging of the printer, whereby ink 1 was prepared.

[Preparation of ink 2]
Ink 2 was prepared in the same manner as in the preparation of Ink 1 except that the composition was changed to the following.

Cationic polymerizable compound (oxetane compound Aron oxetane OXT221 manufactured by Toagosei Co., Ltd.) 70 parts by mass Cationic polymerizable compound (alicyclic epoxy compound Celoxide 2021P manufactured by Daicel Chemical Industries) 30 parts by mass Photopolymerization initiator (SP152 triarylsulfonium salt active ingredient) 50% manufactured by Asahi Denka Co., Ltd.) 10 parts by weight Pigment (CI pigment Blue 15: 4) 4 parts by weight Dispersant (PB822, manufactured by Ajinomoto Fine Techno Co., Ltd.) 0.8 parts by weight [Preparation of Ink 3]
Ink 3 was prepared in the same manner as in the preparation of Ink 1 except that the composition was changed to the following.

Cationic polymerizable compound (Oxetane compound Aron oxetane OXT221 manufactured by Toagosei Co., Ltd.) 70 parts by weight Cationic polymerizable compound (epoxy compound, epoxidized vegetable oil Sansosizer E4030, Shin Nippon Rika Co., Ltd.) 30 parts by weight Tackifier (Harimak M453 rosin-modified maleic acid) Resin Harima Kasei)
3.4 parts by mass Photopolymerization initiator (SP152 triarylsulfonium salt, active ingredient 50% manufactured by Asahi Denka Co., Ltd.) 5 parts by mass Pigment (CI pigment Blue 15: 4) 4 parts by mass Dispersant (PB822 Ajinomoto Fine Techno Co., Ltd.) Manufactured) 0.8 parts by mass [Preparation of Ink 4]
Ink 4 was prepared in the same manner as in the preparation of ink 1 except that the composition was changed to the following.

Cationic polymerizable compound (oxetane compound Aron oxetane OXT221 manufactured by Toagosei Co., Ltd.) 70 parts by mass Cationic polymerizable compound (alicyclic epoxy compound Celoxide 2021P manufactured by Daicel Chemical Industries) 30 parts by mass Tackifier (Harimak M453 rosin-modified maleic acid resin Harima Conversion)
3.4 parts by mass Photopolymerization initiator (SP152 triarylsulfonium salt, active ingredient 50% manufactured by Asahi Denka Co., Ltd.) 10 parts by mass Pigment (CI pigment Blue 15: 4) 4 parts by mass Dispersant (PB822 Ajinomoto Fine Techno Co., Ltd.) 0.8 parts by mass << Inkjet image recording >>
Each ink prepared above is loaded into an ink jet recording apparatus having the structure shown in FIG. 1 having a piezo ink jet nozzle, and a polyethylene terephthalate having a width of 600 mm and a length of 500 m and a thickness of 120 μm (hereinafter referred to as PET). A solid image and image recording consisting of one dot were continuously performed on the film. When the ink landed, this PET film guided the conveyance and was heated to the temperature shown in Table 1 with a heat plate that generated heat, and images 1 to 6 were created.

The ink supply system was composed of an ink tank, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, and a piezo head. The ink was insulated from the front chamber tank to the head portion and heated at 50 ° C. The piezo head was driven so that multi-size dots of 4 to 28 pl could be ejected at a resolution of 360 × 360 dpi, and each ink was ejected continuously. After each ink landed, the lamp unit on both sides of the carriage was irradiated with ultraviolet rays at a setting of 140 W / cm using Vzero as an ultraviolet irradiation light source. At this time, when the piezo head speed was 800 mm / s, the integrated light amount on the film was 17 mJ / cm ² . The integrated light quantity was measured as an integrated illuminance of 254 nm using UVPF-A1 manufactured by Iwasaki Electric Co., Ltd.

<Evaluation of recorded images>
[Measurement of curing speed]
Each ink droplet was ejected onto the substrate at a rate of 4 pl and 20 pL, and the piezo head speed was changed in units of 50 mm / s from 50 to 800 mm / s in units of 50 mm / s, and image recording was performed according to the inkjet image recording method described above.

  After the curing process, the surface of each dot is rubbed with a finger to obtain the maximum piezo head speed at which the cured ink droplet does not peel off from the substrate, which is defined as the curing speed, and this curing speed is a measure of adhesion. did.

  Table 1 shows the evaluation results obtained as described above.

  As is clear from the results in Table 1, an image formed using the ink of the present invention containing 3.0% by mass of the tackifier as a non-reactive resin was compared with the base material relative to the comparative example. It can be seen that the adhesion is excellent and the curing speed is fast. Furthermore, it turns out that the effect is exhibited more by performing the heat processing of a base material.

Example 2
In the creation of images 1 to 4 described in Example 1, images 7 to 10 were prepared in the same manner except that the ultraviolet irradiation light source and the heating temperature of the substrate were changed as described below. In the same manner as in the method, the adhesiveness and the curing rate were subjected to surface K, and the results obtained are shown in Table 2.

Ultraviolet ray irradiation light source: Low-pressure mercury lamp (manufactured by Iwasaki Electric Co., Ltd.). This light source has a total exposure energy of 9 mJ / cm ² received by the PET film when it is passed at a speed of 800 mm / s.

  Substrate heating temperature: 40 ° C

  As is clear from the results in Table 2, the image formed using the ink of the present invention containing 3.0% by mass of the tackifier as a non-reactive resin as in the results of Example 1 is as follows. It can be seen that, compared with the comparative example, the adhesiveness to the substrate is excellent and the curing speed is fast.

Example 3
<Preparation of inkjet ink>
[Preparation of Ink 5]
Radical polymerizable compound (1,6-hexanediol diacrylate) 70 parts by mass Radical polymerizable compound (isobornyl acrylate) 30 parts by mass Photopolymerization initiator (Irgacure 369, manufactured by Ciba Specialty Chemicals)
7 parts by mass Pigment (CI pigment Blue 15: 4) 4 parts by mass Dispersant (PB822 manufactured by Ajinomoto Fine-Techno Co., Ltd.) 0.8 parts by mass 0.8% by mass of the above-described dispersant (PB822 manufactured by Ajinomoto Fine Techno Co., Ltd.) Then, each of the above radical polymerizable compounds was placed in a stainless beaker and stirred and mixed for 1 hour while being heated on a hot plate at 65 ° C. to dissolve. Next, after adding a pigment to this solution, it was sealed in a plastic bottle together with 200 g of zirconia beads having a diameter of 1 mm, and subjected to a dispersion treatment with a paint shaker for 2 hours. Next, zirconia beads were removed, a photoacid generator was added, and this was filtered through a 0.8 μm membrane filter to prevent clogging of the printer, thereby preparing ink 5.

[Preparation of Ink 6]
Ink 6 was prepared in the same manner except that the composition of ink 5 was changed to the following composition.

Radical polymerizable compound (1,6-hexanediol diacrylate) 70 parts by mass Radical polymerizable compound (isobornyl acrylate) 30 parts by mass Tackifier (Harimak M453 rosin-modified maleic acid resin Harima Kasei)
4 parts by weight Photopolymerization initiator (Irgacure 369, Ciba Specialty Chemicals)
7 parts by mass Pigment (CI pigment Blue 15: 4) 4 parts by mass Dispersant (PB822 manufactured by Ajinomoto Fine-Techno Co., Ltd.) 0.8 parts by mass << Inkjet image recording and image evaluation >>
The inks 5 and 6 prepared above were subjected to inkjet image recording and image evaluation in the same manner as in the method described in Example 1, and the results obtained are shown in Table 3. In addition, evaluation of curability evaluated the curability of 1 dot when it is set to 20 pl as an ink droplet.

  As is clear from the results of Table 3, as with the results of Example 1, the radically polymerizable ink of the present invention containing 3.0% by mass of the tackifier as a non-reactive resin was formed. It can be seen that the obtained image is superior to the comparative example in adhesion to the substrate and has a high curing rate.

It is a front view which shows the structure of the principal part of the recording device used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording device 2 Head carriage 3 Recording head 4 Irradiation means 5 Platen part 6 Guide member 7 Bellows structure P Recording medium

Claims (6)

In a photopolymerizable inkjet ink containing at least a colorant, a polymerizable compound, a photopolymerization initiator, and a non-reactive resin, an adhesive or tacky resin is used as the non-reactive resin for 1 to 10 of the entire ink. An ink-jet ink comprising: mass%. The inkjet ink according to claim 1, wherein the adhesive or tacky resin is a tackifier having a softening point of 120 ° C. or lower. The polymerizable compound is at least one selected from a cationic polymerizable epoxy compound, an oxetane compound, and a vinyl ether compound, and the photopolymerization initiator is a photoacid generator. 2. An ink-jet ink as described in 2. The ink-jet ink according to any one of claims 1 to 3, wherein the viscosity at 50 ° C is 20 mPa · s or less. An inkjet recording method for curing an image by irradiating with light after ejecting the inkjet ink according to any one of claims 1 to 4 from an inkjet nozzle onto a substrate, wherein the inkjet ink is used at the time of ejection. A recording method, wherein the ink droplet size is 4 to 40 pl. 6. The recording method according to claim 5, wherein the ink jet ink landed on the substrate is subjected to a heat treatment at the time of light irradiation or after light irradiation.

Images