JP2010023335A - Ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-speed ink jet recording method which excels in printing qualities such as the printed character quality and the fine line reproducibility and can obtain ink jet recorded objects of stable printing quality. <P>SOLUTION: The ink jet recording method is characterized by recording by a single pass system using ink cured with active energy beam on a recording medium having the ratio of hydrogen bond composition (γsH) of surface energy (γsH/γs) to all surface energies (γs) being smaller than 0.1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-speed ink jet recording method which can obtain an ink jet recorded product having excellent print quality such as character quality and fine line reproducibility and stable print quality.

  In recent years, the inkjet recording method can be easily and inexpensively produced images, 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.

  The UV inkjet method has been attracting attention in recent years because 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, and a UV curable inkjet ink has been disclosed. (For example, refer to Patent Document 1).

  Among these, an ink using a cationically polymerizable compound has an advantage that it can be cured even with a light source with low energy illuminance because it does not receive an oxygen inhibition action (see, for example, Patent Document 2).

  The ink jet method is a serial method in which recording is performed by scanning a plurality of carriages mounted with an ink jet head in a direction perpendicular to the conveyance direction of the recording medium, and the recording medium passes through the ink jet head arranged in the width direction of the recording medium only once. There is a single pass method for recording. In particular, the single pass method is preferred from the viewpoint of recording speed.

  In the single pass method, since recording is performed immediately after recording at high speed or the image is stacked on the web, if the ink is not in a dry state immediately after recording, settling or blocking occurs. In particular, when an ink containing a large amount of solvent is used for a recording medium that is not absorbable or very small, the ink does not dry out and the above problem is remarkably worsened.

  The UV inkjet method is a single-pass method and has particularly low absorbency because the ink is solidified and fixed by UV immediately after the ink is ejected from the head and landed on the recording medium. It is preferably used for a recording medium.

  However, in the single pass method, ink droplets are cured with active energy rays at an early timing after the ink droplets land on the recording medium. Therefore, depending on the recording medium, dot spreading may be insufficient, resulting in streaking and repelling, or due to insufficient leveling. Unevenness of film thickness occurs, resulting in problems such as poor adhesion and poor suitability for recording.

  It has been known for a long time that the surface energy of a recording medium is greatly related to the print quality when recording on a recording medium with low absorbency by inkjet.

  A recording method is described in which ink that is cured by active energy is printed on a recording medium having a surface energy of 36 to 60 mN / m (see, for example, Patent Document 3).

  In addition, a method is described in which ink that is cured with an active energy ray having a surface tension of 25 to 40 mN / m is recorded by inkjet on a recording medium having a surface energy of 65 to 72 mN / m (see, for example, Patent Document 4). .

  However, these only refer to the total surface energy of the recording medium, and do not mention the relationship between the components of the surface energy and the print quality.

There is a description that there is an effect of improving the density of the dots due to the dispersion force component of the surface energy of the recording medium and the ink (see, for example, Patent Document 5), but other components (hydrogen bonding component, polar component) I have not found any correlation.
Special Table 2000-504778 JP 2002-188025 A JP 2003-261799 A European Patent Publication No. 1199181 JP-A-2005-231371

  An object of the present invention is to provide a high-speed ink jet recording method that is excellent in print quality such as character quality and fine line reproducibility, and can obtain an ink jet recorded product having stable print quality.

  The above object of the present invention can be achieved by the following configuration.

  1. Recording on a recording medium having a ratio (γsH / γs) of the surface energy hydrogen bond component (γsH) to the total surface energy (γs) of less than 0.1 using an ink curable with active energy rays, using a single pass method. An inkjet recording method characterized by the above.

  2. 2. The ink jet recording method according to 1 above, wherein the ink is an ink that is polymerized and cured by a cation-type reaction with active energy rays.

  3. 3. The ink jet recording method according to 2 above, wherein the ink contains an oxetane compound, an oxirane compound, and an initiator.

  4). 4. The inkjet recording method according to any one of items 1 to 3, wherein the total surface energy (γs) of the recording medium is 25 to 100 mN / m.

  5. 5. The ink jet recording method according to any one of 1 to 4, wherein the active energy rays are ultraviolet rays.

  6). 6. The ink jet recording method according to any one of 1 to 5, wherein the ink is an ink set including a plurality of colors of ink.

  7). The inkjet recording method according to any one of 1 to 6, wherein the recording medium is at least one selected from printing paper, synthetic paper, and film.

  According to the present invention, it is possible to achieve a high-speed ink jet recording method that is excellent in print quality such as character quality and fine line reproducibility, and that can obtain an ink jet recorded product with stable print quality.

  The present invention will be described in more detail.

<Ink>
In the present invention, by using an ink that is cured by an active energy ray, it is possible to perform recording by a single pass method on a recording medium with low absorbency. The ink that cures with active energy rays contains a compound that polymerizes with active energy rays. Examples of the compound that polymerizes with active energy rays include radically polymerizable compounds and cationically polymerizable compounds. The radical polymerizable compound is a compound that polymerizes by a radical type reaction, and the cationic polymerizable compound is a compound that polymerizes by a cationic type reaction.

<Radically polymerizable compound>
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 a chemical form. Only one kind of radically polymerizable compound may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties. A polyfunctional compound having two or more functional groups is more preferable than a monofunctional compound. More preferably, two or more polyfunctional compounds are used in combination for controlling performance such as reactivity and physical 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 unsaturated monomers, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. Specifically, acryloylmorpholine, phenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl Acrylate, bis (4-acryloxypolyethoxyphenyl) propane, EO-modified bisphenol A diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerin epoxy acrylate, neopentyl glycol diacrylate, 1,6- Hexanediol diacrylate, ethylene glycol dia Relate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, trimethylolpropane triacrylate, Acrylic acid derivatives such as tetramethylol methane tetraacrylate, oligoester acrylate, N-methylol acrylamide, diacetone acrylamide, epoxy acrylate, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, allyl methacrylate, glycine Methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane Examples include methacryl derivatives such as trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate, and the like. , Yamashita Shinzo, “Crosslinking agent handbook” (Taisei, 1981); Kato Kiyomi, “UV and EB curing han Dobook (raw material edition) "(1985, Polymer publication society); Radtech study group edition," Application and market of UV / EB curing technology ", p. 79, (1989, CMC); Eiichiro Takiyama," Polyester Commercially available products described in “Resin Handbook”, (1988, Nikkan Kogyo Shimbun), or radically polymerizable or crosslinkable monomers, oligomers and polymers known in the industry can be used. The amount of the radical polymerizable compound added is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

<Cationically polymerizable compound>
In the present invention, an ink that is polymerized and cured by a cationic reaction with active energy rays is preferable. The ink that is polymerized and cured by the cationic reaction is excellent in terms of flexibility and rigidity and adhesion to a rigid recording medium with little curing shrinkage. In addition, since there is no influence of oxygen inhibition during the polymerization reaction, it is excellent in terms of making ink droplets smaller and making the coating film thinner.

  Examples of the cationic polymerizable compound used in the present invention include a compound having an oxetane ring (hereinafter referred to as an oxetane compound), a compound having an oxirane ring (hereinafter referred to as an oxirane compound), and a vinyl ether compound.

<Oxetane compound>
The oxetane compound as a cationically polymerizable compound that can be used in the present invention is a compound having one or more oxetane rings in the molecule. Specifically, 3-ethyl-3-hydroxymethyloxetane (trade name OXT101 manufactured by Toagosei Co., Ltd.), 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene (OXT121 etc.) ), 3-ethyl-3- (phenoxymethyl) oxetane (OXT211 etc.), di (1-ethyl-3-oxetanyl) methyl ether (OXT221 etc.), 3-ethyl-3- (2-ethylhexyloxymethyl) ) Oxetane (OXT212, etc.) can be preferably used, and in particular, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3- (phenoxymethyl) oxetane, di (1-ethyl-3-oxetanyl) methyl Ether can be preferably used. These can be used alone or in combination of two or more.

  The oxetane compound of the present invention is preferably contained in the ink curable with the active energy ray of the present invention in an amount of 5 to 95% by mass, more preferably 20 to 80% by mass.

<Oxirane compounds>
Examples of the oxirane compound include epoxy compounds such as the following aromatic epoxides, alicyclic epoxides, and aliphatic epoxides.

  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 its alkylene oxide adducts, and novolak-type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxide, cyclohexene oxide 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. Or a cyclopentene oxide containing compound is preferable.

  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 Diglycidyl ethers of polyalkylene glycols such as diglycidyl ethers, polypropylene glycols or diglycidyl ethers of adducts thereof Tel 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.

  Examples of the most preferred alicyclic epoxide in the present invention include those described in JP-A Nos. 2004-315778 and 2005-28632.

  Specific compounds are described below.

  In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

  These oxirane compounds are preferably contained in the ink curable with the active energy ray of the present invention in an amount of 5 to 95% by mass, more preferably 20 to 80% by mass.

<Vinyl ether compound>
Vinyl ether compounds as cationically polymerizable compounds that can be used in the present invention include, for example, ethylene glycol divinyl ether, ethylene glycol monovinyl ether, diethylene glycol divinyl ether, triethylene glycol monovinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, Di- or trivinyl ether compounds such as dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexane dimethanol divinyl ether, hydroxyethyl monovinyl ether, hydroxynonyl monovinyl ether, trimethylolpropane trivinyl ether, ethyl vinyl ether, n- Butyl vinyl ether, Sobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether-o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl Examples thereof include monovinyl ether compounds such as vinyl ether.

<Initiator>
<Radical polymerization initiator>
Examples of radical polymerization initiators that can be used in the present invention include conventionally known radicals described in “Applications and Markets of UV / EB Curing Technology” (CMC Publishing Co., Ltd., edited by Yoneho Tabata, edited by Radtech Research Association). A polymerization initiator can be used. The initiator is preferably a molecular cleavage type or a hydrogen abstraction type. Specific examples include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (4- Morpholinophenyl) -butan-1-one, bis (2,4,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 1,2-octanedione, 1- (4- (phenylthio) -2,2- (O-benzoyloxime)) and the like. Further, as other molecular cleavage types, 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyldimethyl ketal, 2-hydroxy-2-methyl- 1-phenylpropan-1-one, 1 (4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one may be used in combination. Furthermore, hydrogen abstraction type photopolymerization initiators such as benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4′-methyl-diphenyl sulfide can be used in combination.

  For the above photo radical polymerization initiator, for example, trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzyl. Amines that do not cause an addition reaction with the polymerizable component, such as amines and 4,4′-bis (diethylamino) benzophenone, can also be used in combination.

<Cationic polymerization initiator>
The ink curable with active energy rays according to the present invention preferably contains a cationic polymerization initiator as a photopolymerization initiator together with the cationic polymerizable compound.

  Specific examples of the cationic polymerization initiator include a photoacid generator and the like. For example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “ Organic materials for imaging ", Bunshin Publishing (1993), see pages 187-192). Examples of compounds suitable for the present invention are listed below.

First, diazonium, ammonium, iodonium, sulfonium, aromatic onium compounds of phosphonium such as ^{_{B (C 6 F 5) 4}} -, PF 6 -, AsF 6 -, SbF 6 -, CF 3 SO 3 - and salts be able to.

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

  Secondly, sulfonated compounds 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.

<Sensitizer>
In the ink curable with the active energy ray according to the present invention, it is preferable to use a sensitizer having an ultraviolet spectrum absorption at a wavelength longer than 300 nm. For example, a hydroxyl group or an optionally substituted aralkyloxy group is used as a substituent. Alternatively, a polycyclic aromatic compound having at least one alkoxy group, a carbazole derivative, a thioxanthone derivative, and the like can be given.

  As the polycyclic aromatic compound that can be used in the present invention, naphthalene derivatives, anthracene derivatives, chrysene derivatives, and phenanthrene derivatives are preferable. As an alkoxy group which is a substituent, a C1-C18 thing is preferable and a C1-C8 thing is especially preferable. As the aralkyloxy group, those having 7 to 10 carbon atoms are preferable, and benzyloxy groups and phenethyloxy groups having 7 to 8 carbon atoms are particularly preferable.

  Examples of these sensitizers that can be used in the present invention include carbazole derivatives such as carbazole, N-ethylcarbazole, N-vinylcarbazole, N-phenylcarbazole, 1-naphthol, 2-naphthol, 1-methoxynaphthalene, 1-stearyloxynaphthalene, 2-methoxynaphthalene, 2-dodecyloxynaphthalene, 4-methoxy-1-naphthol, glycidyl-1-naphthyl ether, 2- (2-naphthoxy) ethyl vinyl ether, 1,4-dihydroxynaphthalene, 1, , 5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,7-dimethoxynaphthalene, 1,1′-thiobis (2-naphthol), 1,1′-bi-2-naphthol, 1,5-naphthyl diglycid Ether, 2,7-di (2-vinyloxyethyl) naphthyl ether, 4-methoxy-1-naphthol, ESN-175 (epoxy resin manufactured by Nippon Steel Chemical Co., Ltd.) or its series, condensate of naphthol derivative and formalin, etc. Naphthalene derivatives, 9,10-dimethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, 2-tbutyl-9,10-dimethoxyanthracene, 2,3-dimethyl-9,10-dimethoxyanthracene, 9-methoxy -10-methylanthracene, 9,10-diethoxyanthracene, 2-ethyl-9,10-diethoxyanthracene, 2-tbutyl-9,10-diethoxyanthracene, 2,3-dimethyl-9,10-di Ethoxyanthracene, 9-ethoxy-10-methylanthracene, 9, 0-dipropoxyanthracene, 2-ethyl-9,10-dipropoxyanthracene, 2-tbutyl-9,10-dipropoxyanthracene, 2,3-dimethyl-9,10-dipropoxyanthracene, 9-isopropoxy- 10-methylanthracene, 9,10-dibenzyloxyanthracene, 2-ethyl-9,10-dibenzyloxyanthracene, 2-tbutyl-9,10-dibenzyloxyanthracene, 2,3-dimethyl-9,10 -Dibenzyloxyanthracene, 9-benzyloxy-10-methylanthracene, 9,10-di-α-methylbenzyloxyanthracene, 2-ethyl-9,10-di-α-methylbenzyloxyanthracene, 2-tbutyl -9,10-di-α-methylbenzyloxyanthracene, 2,3- Dimethyl-9,10-di-α-methylbenzyloxyanthracene, 9- (α-methylbenzyloxy) -10-methylanthracene, 9,10-di (2-hydroxyethoxy) anthracene, 2-ethyl-9,10 -Anthracene derivatives such as di (2-carboxyethoxy) anthracene, 1,4-dimethoxychrysene, 1,4-diethoxychrysene, 1,4-dipropoxychrysene, 1,4-dibenzyloxychrysene, 1,4- Examples include chrysene derivatives such as di-α-methylbenzyloxychrysene, phenanthrene derivatives such as 9-hydroxyphenanthrene, 9,10-dimethoxyphenanthrene, and 9,10-diethoxyphenanthrene. Among these derivatives, 9,10-dialkoxyanthracene derivatives which may have an alkyl group having 1 to 4 carbon atoms as a substituent are particularly preferable, and the methoxy group and ethoxy group are preferable as the alkoxy group.

  Examples of the thioxanthone derivative include thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone 2-chlorothioxanthone, and the like.

<Starting aid>
An initiator is a substance that acts as a sensitizing dye that improves the radical or acid generation efficiency of an initiator by donating energy to the initiator by light irradiation, electron donation, electron attraction, heat generation, etc. Yes, applied in combination with initiator.

  Examples of the initiation assistant include xanthene, thioxanthone dye, ketocoumarin, thioxanthene dye, 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, pyrylium compound, pyromethene compound, pyrazolotriazole compound, benzothiazole compound, barbituric acid derivative, thiobarbituric acid derivative and the like can be applied.

  In addition to the above-mentioned compounds, it is well known that the initiator acts as a sensitizing dye in documents such as “Development technology of polymer additives” (CMC Publishing Co., Ltd., supervised by Junichi Daikatsu). The substance may be applied. The initiation assistant can also be regarded as a component that forms part of the photopolymerization initiator.

  In addition to these photoinitiators, an accelerator aid may be added to accelerate the photopolymerization (curing) reaction. Examples of these include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, triethanolamine and the like.

  Examples of combinations of radical polymerization initiators and initiator aids applied to radically polymerizable compounds include radical acid initiators as peracid esters and initiator assistants as xanthene, thioxanthone dyes, ketocoumarins, and thiopyrylium salts. And a combination of an onium salt such as diphenyliodonium salt which is a radical polymerization initiator and a thioxanthene dye which is an initiation assistant are well known.

  Further, when applying titanocenes as radical polymerization initiators, as initiators for sensitizing the titanocenes from visible light to near infrared light corresponding to lasers or LEDs, for example, 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, pyrylium compound, pyromethene compound, pyrazolotriazole A compound, a benzothiazole compound, a barbituric acid derivative, a thiobarbituric acid derivative, or the like can be applied.

  As the starting aid used in combination with titanocene, further, European Patent No. 568,993, US Patent Nos. 4,508,811, 5,227,227, JP 2001-125255 A, JP 11-271969 A, etc. The compounds described in (1) are also applicable. Specific examples of the combination of such a titanocene radical polymerization initiator and an initiation assistant include combinations described in JP-A Nos. 2001-125255 and 11-271969.

<Amine>
In the present invention, an amine compound may be contained from the viewpoint of storage stability of the ink. Examples of the amine compound include octylamine, dodecylamine, octadecylamine, naphthylamine, xylenediamine, dibenzylamine, diphenylamine, dibutylamine, dioctylamine, dimethylaniline, dimethyloctadecylamine, dimethylhexadecylamine, diheptylamine, dimethyl Examples include decylamine, quinuclidine, tributylamine, trioctylamine, tetramethylethylenediamine, tetramethyl-1,6-hexamethylenediamine, hexamethylenetetramine, 2-methylaminoethanol, triisopropanolamine, and triethanolamine. Compounds having a nitrogen atom charge of −0.400 or more are triisopropanolamine, diheptylamine, octylamine Dimethyl decyl amine, dimethyl hexadecyl amine, trioctylamine, dimethyl octadecylamine, dodecylamine, there is octadecyl amine.

<Colorant>
A pigment or dye can be used as the color material used in the ink cured with the active energy ray according to the present invention. From the viewpoint of the weather resistance of the image, it is preferable to use a pigment.

  Various things, such as an organic pigment and / or an inorganic pigment, can be used. Specifically, white pigments such as titanium oxide, zinc white, lead white, litbon, and antimony oxide, black pigments such as aniline black, iron black, and carbon black, yellow lead, yellow iron oxide, Hansa Yellow (100, 50, 30 etc.), yellow pigments such as titanium yellow, benzine yellow and permanent yellow, orange pigments such as chrome vermilon, permanent orange, balkan first orange and indanthrene brilliant orange, brown such as iron oxide, permanent brown and para brown Pigment, Bengala, Cadmium Red, Antimony Zhu, Permanent Red, Rhodamine Lake, Alizarin Lake, Thioindigo Red, PV Carmine, Monolite Fast Red and Quinacridone Red Pigment, Cobalt Purple, Manganese Purple, Purple violet pigments such as first violet, methyl violet lake, indanthrene brilliant violet, dioxazine violet, ultramarine, bitumen, cobalt blue, alkali blue lake, metal free phthalocyanine blue, copper phthalocyanine blue, indanthrene blue and indigo In addition to green pigments such as blue pigment, chrome green, chromium oxide, emerald green, naphthol green, green gold, acid green rake, malachite green rake, phthalocyanine green and polychlorobrom copper phthalocyanine, various fluorescent pigments, metal powder pigments, Examples include extender pigments.

  The pigments that can be preferably used in the present invention are listed below.

  C. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 109, 114, 120, 128, 129, 138, 150, 151, 154, 180, 185, C.I. I. Pigment Red 5, 7, 12, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 101, 112, 122, 123, 144, 146, 168, 184, 185, 202, C.I. I. Pigment Violet 19, 23, C.I. I. Pigment Blue 1, 2, 3, 15: 1, 15: 2, 15: 3, 15: 4, 18, 22, 27, 29, 60, C.I. I. Pigment Green 7, 36, C.I. I. Pigment White 6, 18, 21, C.I. I. Pigment Black 7.

  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, and 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 used in 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 diameter of the pigment particles is 0.08 to 0.2 μm, and the maximum particle diameter is 0.3 to 10 μm, preferably 0.3 to 3 μm. The selection of the dispersion medium, the dispersion conditions, and the filtration conditions are appropriately set. 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 according to the present invention, the color material concentration is preferably 1% by mass to 30% by mass of the entire ink. For inks other than white, 1% by mass and 10% by mass are more preferable.

<Additives>
In addition to the above components, the following materials can be added to the ink curable with the active energy ray of the present invention in an amount of up to 50% by mass in the ink, if necessary.

  Polymer binder, inorganic filler, softener, antioxidant, anti-aging agent, stabilizer, tackifier resin, leveling agent, antifoaming agent, plasticizer, dye, treating agent, viscosity modifier, organic solvent, lubricity Inactive ingredients such as imparting agents and UV blockers can be blended. As the polymer binder, polyester resins, polyurethane resins, vinyl resins, acrylic resins, rubber resins, and waxes are preferable. Examples of inorganic fillers include, for example, zinc oxide, aluminum oxide, antimony oxide, calcium oxide, chromium oxide, tin oxide, titanium oxide, iron oxide, copper oxide, lead oxide, bismuth oxide, magnesium oxide and manganese oxide. Metal / non-metal oxides, hydroxides such as aluminum hydroxide, ferrous hydroxide and calcium hydroxide, salts such as calcium carbonate and calcium sulfate, silicon compounds such as silicon dioxide, kaolin, bentonite, clay and talc Natural pigments, natural zeolite, minerals such as Oya stone, natural mica and ammonite, synthetic inorganic materials such as artificial mica and synthetic zeolite, and various metals such as aluminum, iron and zinc. Some of these may overlap with the pigment, but these may be added to the composition as a filler, if necessary, in addition to the essential pigment. The lubricity-imparting agent is blended for the purpose of improving the lubricity of the resulting coating film. For example, a fatty acid ester wax, silicon wax, fluorine wax, polyolefin, which is an esterified product of a polyol compound and a fatty acid. Mention may be made of waxes such as waxes, animal waxes and plant waxes. Examples of the tackifying resin include rosins such as rosin acid, polymerized rosin acid and rosin acid ester, terpene resin, terpene phenol resin, aromatic hydrocarbon resin, aliphatic saturated hydrocarbon resin, and petroleum resin.

  In preparing the ink curable with the active energy ray of the present invention, the mixing method is not particularly limited as long as the materials constituting these can be sufficiently mixed. Specific examples of the mixing method include a stirring method using a stirring force accompanying the rotation of the propeller, a roll kneading method, and a normal disperser such as a sand mill.

<Ink viscosity>
In the ink curable with the active energy ray of the present invention, the viscosity at 25 ° C. is preferably 5 to 500 mPa · s, in order to obtain good curability regardless of the curing environment (temperature / humidity).

<Description of single pass method>
In the present invention, high-speed printing is possible by a single-pass inkjet method. The single pass method is a method in which recording is performed by passing the recording medium only once through a line head in which inkjet heads are arranged in the width of the recording medium. Compared with the serial ink jet system that scans a plurality of times, the recording speed is remarkably high. However, since the single-pass method is used for recording only once, there is a problem that a failure such as a streak is likely to occur due to repelling caused by liquid between dots that are continuously hit. In addition, if it is a serial type, it can be corrected by multiple scans even if creases or streaks occur. In the single pass method, since the recording is performed only once, there is a problem that those failures cannot be corrected.

<Active energy rays>
Examples of active energy rays that can be used in the present invention include ultraviolet rays, electron beams, X-rays, radiation, and high frequencies, and ultraviolet rays are most economically preferable. Examples of the ultraviolet light source include an ultraviolet laser, a mercury lamp, a xenon lamp, a sodium lamp, an alkali metal lamp, and the like, and a laser beam is particularly preferable when a light collecting property is required.

  Since the active energy ray is irradiated by a single pass printing method, a light source is arranged behind the line head and irradiation is performed after recording. When there are a plurality of inks, a light source may be provided after each line head to irradiate each recording of each ink, or all the ink may be emitted after being emitted from the line head and then irradiated last.

<Recording medium>
Various paper, synthetic paper, film, metal, glass, cloth and the like are used as a recording medium used in the present invention. Among them, printing paper and synthetic paper. A film is preferred. Various types of paper include high-quality paper and coated paper. From the viewpoint of printing quality, coated paper for printing is preferable. Examples of the coated paper for printing include finely coated paper, art paper, cast coated paper, and the like, and those sold by each paper manufacturer can be used. Synthetic paper is a film with a texture of paper, specifically, YUPO manufactured by YUPO Corporation, Crisper manufactured by Toyobo, Carrelet manufactured by Chisso, and peach coat manufactured by Nisshinbo. The film is used for printing, packaging, sign display and the like, and the material includes polyester, polyolefin, polystyrene, polyvinyl chloride, acrylic resin, epoxy resin, melamine resin and the like.

<Surface energy of recording medium>
In the present invention, the ratio (γsH / γs) of the surface energy of the recording medium to the total surface energy (γs) of the hydrogen bond component (γsH) is smaller than 0.1. When γsH / γs is in the above range, it is possible to obtain an ink jet recorded product having excellent print quality such as character quality and fine line reproducibility and stable print quality. In addition, it has become possible to obtain stable print quality even when inks having different surface tensions are used.

  The total surface energy (γs) of the recording medium affects the wettability of the ink. If the recording medium has a low total surface energy, the wetting and spreading of ink is poor, and the formed dot diameter becomes small, so that streaks and repellency are likely to occur. The wetting and spreading of the ink is improved to some extent by increasing the total surface energy and decreasing the surface tension of the ink, but it is still insufficient for high print quality, and the hydrogen bond of the surface energy of the recording medium has a further effect. Ingredients are involved. Further, γsH / γs is involved in controlling the wetting spread to obtain an appropriate print quality. If γsH / γs is 0, that is, if there is no hydrogen bonding component, the wetting spread of the ink becomes extremely worse and a sufficiently large dot diameter cannot be obtained. When γsH / γs is 0.1 or more, when recording is performed using inks having different surface tensions, the dot diameter changes greatly, and stable print quality cannot be obtained. Further, since there is a difference in wetting spread, streaky density unevenness occurs.

  Since ink that cures with active energy rays has a relatively high polarity, wetting spread of the ink greatly increases as the ratio of the hydrogen bond component of the surface energy increases. In particular, when the surface tension of the ink is low, the ink easily wets and spreads. For this reason, when γsH / γs is 0.1 or more, when recording is performed using inks having different surface tensions, the difference in wetting and spreading of dots becomes large, and stable print quality cannot be obtained.

  The total surface energy (γs) of the recording medium is more preferably 25 to 100 mN / m. If the total surface energy is less than 25 mN / m, the ink may not be wet and the dot diameter may not be sufficient for print quality. If it is greater than 100 mN / m, the ink wetting spreads too much, and the reproducibility of fine characters may deteriorate.

<Surface energy measurement method>
The surface energy of the recording medium is calculated by measuring the contact angle of a liquid whose surface energy is known (γsD: dispersion force component, γsP: polar component, γsH: hydrogen bond component) and using the Young-Fowkes equation. it can. For example, it is described in Ikuo Ishii et al., “Wetting Technology Handbook (issued in 2001)” (published by Techno System).

<Method for controlling surface energy of recording medium>
As a method for controlling the total surface energy (γs) of the recording medium and the hydrogen bond component (γsH) of the surface energy within a preferable range, a method of surface-treating the recording medium or surface-coating the recording medium can be mentioned. As the surface treatment, there are a method of physically and chemically treating the surface of the recording medium, for example, corona discharge, flame treatment, plasma treatment, sputtering, and a method of providing a coating layer on the surface of the recording medium.

  As a method for providing the surface coat layer, a coat layer can be provided by a known coating method. Specific coating methods include bar coater coating, roller coating, spin coating, spray coating, blade coating, gravure coating, extrusion coating, and inkjet coating. The surface coat may be provided off-line or may be provided in-line before ink jet recording. In addition, a coat layer may be provided by inkjet before printing the ink by inkjet. The surface treatment may be performed on the entire surface of the recording medium or only on the portion where ink jet recording is performed.

  Examples of the present invention will be specifically described below, but the embodiments of the present invention are not limited to these examples.

Example 1
<Preparation of ink 1 (radical polymerization type)>
Ink formula 1
CI pigment black 7: 3 parts Lauryl acrylate: 31.9 parts Tetraethylene glycol diacrylate: 35.5 parts Caprolactam-modified dipentaerythritol hexaacrylate: 22.5 parts Shin-Etsu Silicon KF-352: 0.1 part Ciba Japan Manufactured by Irgacure 184: 5 parts Ciba Japan Irgacure 369: 5 parts Dispersant Ajinomoto Fine Techno PB822: 2 parts An ink was prepared as described below using the ink composition described above. In addition, a unit represents a mass part.

  In the ink formulation 1, the photopolymerizable compound and the dispersant are put into a stainless beaker, and are stirred and mixed for 1 hour while being heated on a 65 ° C. hot plate, and dissolved. Add color material to this, put it in a plastic bottle together with 200 g of zirconia beads with a diameter of 1 mm, seal it with a paint shaker for 2 hours, remove the zirconia beads, and add the remaining material shown in Ink Formula 1 Stir and mix. Further, the surface tension was adjusted to 30 mN / m with a surfactant (KF351 manufactured by Shin-Etsu Chemical Co., Ltd.).

  Then, it filtered with a 0.8 micrometer membrane filter, and produced the ink 1.

<Preparation of ink 2 (radical polymerization type)>
Ink 2 was produced in the same manner as ink 1 except that the surface tension was 23 mN / m.

Preparation of Pigment Dispersion A pigment dispersion containing a pigment was prepared according to the following method.

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

Dispersant (Ajinomoto Fine Techno PB822): 10 parts Oxetane (Toa Gosei OXT-221): 70 parts After cooling the above solution to room temperature, 10 parts of CI pigment Black 7 was added thereto, After 200 g of zirconia beads were put in a glass bottle and sealed, the dispersion was processed with a paint shaker for the following time, and then the zirconia beads were removed to prepare a pigment dispersion.

<Preparation of ink 3 (cationic polymerization type)>
Ink formula 3
Pigment dispersion: 10 parts Oxetane (OXA-221 made by Toa Gosei): 54.5 parts Oxetane (OXT-212 made by Toa Gosei): 10 parts Epoxy compound (EP-17): 21 parts Photoinitiator (CPI- made by San Apro) 100P): 2.5 parts Sensitizer (DEA manufactured by Kawasaki Kasei Kogyo Co., Ltd.): 2 parts The ink composition described above was added and stirred, and the surface tension was 30 mN / second with a surfactant (KF351 manufactured by Shin-Etsu Chemical Co., Ltd.). It adjusted so that it might become m. Then, the ink 3 was produced by filtering with a 0.8 micrometer membrane filter.

<Preparation of ink 4 (cationic polymerization type)>
Ink 4 was produced in the same manner as ink 3 except that the surface tension was 23 mN / m.

<Recording medium>
Untreated PET was used as the recording medium.

<Surface treatment of recording medium>
Using an atmospheric pressure plasma processing apparatus, the recording medium was processed so that the surface energy shown in Table 1 was obtained by adjusting the type and output of the gas.

<Measurement of surface energy of recording medium>
The surface energy (γsD: dispersive force component, γsP: polar component, γsH: hydrogen bond component) of the recording medium was determined by measuring the contact angle of water, propylene carbonate, and methylene iodide using the Young-Fowkes equation. The contact angle was 200 ms after dropping the droplet.

<Inkjet recording>
Inkjet recording was performed using an inkjet print unit SP-L2130 manufactured by Konica Minolta. The recording speed is 30 m / min and is a single pass system. A UV lamp manufactured by GS Yuasa was used. The resolution is 360 dpi × 360 dpi (dpi represents 1 dot, that is, the number of dots per 2.54 cm). Printing by the scan method was performed using an ink jet evaluation apparatus XY-100 manufactured by Konica Minolta, but the recording speed was 1 m / min, which was significantly slower than the single pass method.

<Evaluation of outline character quality>
7-point alphanumeric white letters were visually evaluated.

○: Characters can be clearly recognized △: Some outlines are blurred but characters can be recognized ×: Characters are blurred and difficult to recognize <Density unevenness evaluation method>
The solid portion was visually observed to evaluate density unevenness.

○: Density unevenness is not observed Δ: Density unevenness is slightly observed ×: Density unevenness is conspicuous <Method for evaluating fine line reproducibility>
Two continuous lines of dots were visually observed and evaluated for curling, constriction, and thickening of the lines.

○: No curling or constriction, no line thickening △: Slight curling, constriction, line thickening, etc. can be confirmed slightly ×: Curling, constriction, line thickening, etc. are conspicuous.

<Recording speed>
○: 30 m / min
×: 1 m / min
<Bendability>
The solid print portion was repeatedly mountain-folded and fold-folded 60 times to evaluate the bending resistance.

○: No change Δ: A thin streak remains in the bent portion ×: A crack enters the bent portion and the film is peeled off.

  The obtained results are shown in Table 1.

  As is apparent from Table 1, according to the ink jet recording method of the present invention, the ink jet recording method is a high speed ink jet recording method that is excellent in print quality such as character quality and fine line reproducibility, and can obtain an ink jet recorded product with stable print quality. I understand.

Claims (7)

Recording on a recording medium having a ratio (γsH / γs) of the surface energy hydrogen bond component (γsH) to the total surface energy (γs) of less than 0.1 using an ink curable with active energy rays, using a single pass method. An inkjet recording method characterized by the above. 2. The ink jet recording method according to claim 1, wherein the ink is an ink that is polymerized and cured by a cation-type reaction with active energy rays. The inkjet recording method according to claim 2, wherein the ink contains an oxetane compound, an oxirane compound, and an initiator. The inkjet recording method according to claim 1, wherein the total surface energy (γs) of the recording medium is 25 to 100 mN / m. The inkjet recording method according to claim 1, wherein the active energy rays are ultraviolet rays. The ink jet recording method according to claim 1, wherein the ink is an ink set composed of a plurality of colors of ink. The inkjet recording method according to claim 1, wherein the recording medium is at least one selected from printing paper, synthetic paper, and film.