JP2005060490A - Ink, method for imaging, printed matter and recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink which is jetted from a recording head having at least one nozzle capable of selectively controlling the jetting of ink drops and with which a precise image having a high character quality and gloss with no color mixing is recorded, and a method for imaging, printed matter, and a recoding device using the ink. <P>SOLUTION: The ink is jetted from the recording head having at least one nozzle capable of selectively controlling the jetting of ink drops, cured by actinic rays and contains polyacrylic acid or polymethacrylic acid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel ink and an image forming method, a printed matter, and a recording apparatus using the same, and more specifically, an ink capable of forming a high-definition image excellent in character quality, color mixing resistance, and gloss, and image formation The present invention relates to a method, a printed matter, and a recording apparatus.

  In recent years, the ink jet recording method can easily and inexpensively create an image, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as a color filter. In particular, recording devices that emit and control fine dots, ink with improved color gamut, durability, and emission suitability, ink absorbency, color development, surface gloss, etc. are dramatically improved. It is also possible to obtain image quality comparable to silver halide photography by combining special papers. 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 special paper, the recording material is limited, and the cost of the recording material 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 inkjet method using a solid wax ink at room temperature, a solvent-based inkjet method using an ink mainly composed of a fast-drying organic solvent, or an ultraviolet ray that is crosslinked by ultraviolet (UV) light after image recording. For example, a curable ink jet method. Since this oil-based ink uses an organic solvent or an organic compound, care must be taken in handling from the viewpoint of the environment.

  The ultraviolet curable 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 material having no quick drying and no ink absorption. No. 54667, JP-A-6-200204, and JP 2000-504778 disclose ultraviolet curable ink-jet inks.

  On the other hand, the solvent-free ultraviolet curable ink is preferable because it can be cured immediately after landing so as to suppress bleeding and achieve durability of the finished image and VOC-free. As such ink, ultraviolet curable ink that is ejected and ejected from a minute hole by heating is disclosed in Patent Document 1, and solvent-free ink having the same configuration is disclosed in Patent Documents 2-6. However, these conventional solventless UV curable inks are limited to use only in large lots and low resolution printers.

Thus, development of actinic ray curable water-based inks that are rapidly polymerized by ultraviolet irradiation and that can provide excellent quality (character quality, color mixing resistance, image smoothness) of formed images has been eagerly desired.
JP-A-61-164836 Japanese Patent Laid-Open No. 5-214279 Japanese Patent Laid-Open No. 5-214280 Special Table 2000-504778 WO 99/29787 pamphlet International Publication No. 99/29788 pamphlet

  An object of the present invention is to form a high-definition image which is ejected by a recording head having at least one nozzle capable of selectively controlling the ejection of ink droplets and has excellent character quality, color mixing resistance and image smoothness. It is an object to provide an ink, an image forming method, a printed matter, and a recording apparatus.

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

  1. Ink ejected by a recording head having at least one nozzle capable of selectively controlling ejection of ink droplets, which is cured by actinic rays and contains polyacrylic acid or polymethacrylic acid .

  2. 2. The ink according to 1 above, containing 0.1 to 10% by mass of the polyacrylic acid or polymethacrylic acid.

  3. 3. The ink according to 1 or 2 above, which contains a radical polymerizable monomer and a radical polymerization initiator.

  4). 3. The ink according to 1 or 2 above, which contains a cationic polymerizable monomer and a photoacid generator.

  5). 5. The ink according to item 4, wherein at least one of the cationically polymerizable monomers is an oxetane compound.

  6). 6. The ink according to 5 above, wherein the oxetane compound is a compound having an oxetane ring substituted at the 2-position.

  7). 7. An image forming method comprising: using the ink according to any one of 1 to 6 above; ejecting ink onto a recording material using a recording head; and irradiating with active light to cure the ink.

  8). 8. The image forming method as described in 7 above, wherein the actinic ray is an ultraviolet ray.

  9. 9. The image forming method according to 7 or 8, wherein the amount of ink droplets ejected from each nozzle of the recording head is 2 to 15 pl per ejection.

  10. A printed matter produced by the image forming method according to any one of 7 to 9 using a non-absorbent recording material.

  11. 11. A recording apparatus for use in producing a printed material as described in 10 above, wherein the recording head and ink are heated to 35 to 100 ° C. to eject the ink.

  According to the present invention, it is possible to record a high-definition image that is ejected by a recording head having at least one nozzle capable of selectively controlling the ejection of ink droplets and has excellent character quality, no color mixing, and excellent gloss. An ink that can be used, an image forming method using the ink, a printed material, and a recording apparatus can be provided.

  As a result of intensive studies in view of the above problems, the present inventor is an ink ejected by a recording head having at least one nozzle capable of selectively controlling the ejection of ink droplets, cured by actinic rays, and As a result of finding the ink containing polyacrylic acid or polymethacrylic acid, an ink capable of forming a high-definition image excellent in character quality, color mixing resistance and image smoothness can be realized. is there.

  In addition to the above structure, 0.1 to 10% by mass of polyacrylic acid or polymethacrylic acid, a radically polymerizable monomer and a radical polymerization initiator, a cationically polymerizable monomer and a photoacid generator The effect is further exhibited by containing the ink, at least one of the cationically polymerizable monomers being an oxetane compound, and being an ink having a oxetane ring in which the oxetane compound is substituted at the 2-position. I found out.

  Details of the present invention will be described below.

  The ink of the present invention is characterized by being ejected by a recording head having at least one nozzle capable of selectively controlling ejection of ink droplets, cured by actinic rays, and containing polyacrylic acid or polymethacrylic acid. .

  First, polyacrylic acid or polymethacrylic acid according to the ink of the present invention will be described.

  The polyacrylic acid and polymethacrylic acid according to the present invention are polyacrylic acid, polymethacrylic acid and derivatives thereof or alkali salts thereof, specifically, polyacrylic acid, sodium polyacrylate and polyacrylic acid. It is an ester copolymer or an alkali salt thereof, and the copolymer is preferably a crosslinked branched type. As the alkali salt of polyacrylic acid, sodium salt, potassium salt, calcium salt and the like can be used, but use of sodium salt is preferable from the viewpoint of availability.

  The polymethacrylic acids according to the present invention are methacrylic monomers classified into non-functional monomers such as methyl methacrylate, monofunctional monomers such as diethylaminoethyl methacrylate, and polyfunctional monomers such as ethylene dimethacrylate. It is a methacrylic ester synthetic resin containing an acid or an alkali metal salt thereof and a copolymer.

  The acrylic acid-methacrylic acid copolymer according to the present invention is a copolymer having a molecular weight of 5,000 to 20,000, and sodium salts and potassium salts can be used. The use of sodium salts is preferred. The copolymerization ratio of acrylic acid and methacrylic acid is preferably such that acrylic acid / methacrylic acid has a mass ratio of 9/1 to 4/6.

  In the ink of the present invention, the content of polyacrylic acid or polymethacrylic acid is preferably 0.1 to 10% by mass, more preferably 0.1 to 5.0% by mass.

  The ink of the present invention preferably contains a radical polymerizable monomer (hereinafter also referred to as a radical polymerizable substance) and a radical polymerization initiator.

  The radically polymerizable substance is a compound having an ethylenically unsaturated bond capable of radical polymerization, and any compound having at least one ethylenically unsaturated bond capable of radical polymerization in the molecule may be used. , Oligomers, polymers and the like having a chemical form. Only one kind of radically polymerizable substance may be used, or two or more kinds 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 substances such as unsaturated anhydrides, acrylonitrile, styrene, 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, Yamashita Junzo, “Crosslinker Handbook”, (1981 Taiseisha); Kato Kiyomi, “UV / EB Curing Handbook (Materials)” (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 amount of the radical polymerizable substance added is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

  Examples of the radical polymerization initiator include triazine derivatives described in JP-B-59-1281, JP-B-61-9621, JP-A-60-60104, JP-A-59-1504 and JP-A-61. No. 243807, etc., Japanese Patent Publication No. 43-23684, Japanese Examined Publication No. 44-6413, Japanese Examined Publication No. 44-6413, Japanese Examined Publication No. 47-1604, etc. A diazonium compound described in US Pat. No. 3,567,453, an organic azide compound described in US Pat. Nos. 2,848,328, 2,852,379, and 2,940,853, Ortho-quinonediazides described in JP-B 36-22062, JP-B 37-13109, JP-B 38-18015, JP-B 45-9610, etc. Various onium compounds described in JP-A-5-39162, JP-A-59-14023, and the like, and “Macromolecules, Vol. 10, page 1307 (1977),” JP-A-59-142205. Azo compounds described in Japanese Patent Publication No. 1-54440, European Patent No. 109,851, European Patent No. 126,712, etc., “Journal of Imaging Science” (J. Imag .Sci.) ", Vol. 30, page 174 (1986), (oxo) sulfonium compounds described in Japanese Patent Application No. 4-56831 and Japanese Patent Application No. 4-89535. Organic boron complexes, titanocenes described in JP-A-61-151197, “Coordination Chemistry Levi (Coordination Chemistry Review), 84, 85-277 (1988) and JP-A-2-182701, transition metal complexes containing transition metals such as ruthenium, JP-A-3-209477 No. 2,4,5-triarylimidazole dimer, carbon tetrabromide, and organic halogen compounds described in JP-A-59-107344. These polymerization initiators are preferably contained in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the compound having an ethylenically unsaturated bond capable of radical polymerization.

  The ink of the present invention preferably contains a cationic polymerizable monomer and a photoacid generator.

  As a cationic polymerization type photocurable resin comprising a cationic polymerizable monomer that can be used in the present invention, an epoxy type ultraviolet curable prepolymer of a type that is polymerized by cationic polymerization, a monomer has an epoxy group in one molecule. And a prepolymer containing 2 or more. Examples of such prepolymers include alicyclic polyepoxides, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyhydric alcohols, polyglycidyl ethers of polyoxyalkylene glycols, and polyglycidyls of aromatic polyols. Examples include ethers, hydrogenated compounds of polyglycidyl ethers of aromatic polyols, urethane polyepoxy compounds, and epoxidized polybutadienes. One of these prepolymers can be used alone, or two or more thereof can be mixed and used.

  Other examples of the cationic polymerizable compound contained in the cationic polymerizable composition include the following (1) styrene derivatives, (2) vinyl naphthalene derivatives, (3) vinyl ethers, and (4) N-vinyl compounds. Can be mentioned.

(1) Styrene derivatives For example, styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, p-methoxy-β-methylstyrene, etc. (2) Vinyl naphthalene derivatives For example, 1-vinyl naphthalene, α-methyl-1-vinyl naphthalene, β-methyl-1-vinyl naphthalene, 4-methyl-1-vinyl naphthalene, 4-methoxy-1-vinyl naphthalene, etc. (3) Vinyl ether For example, isobutyl vinyl ether, ethyl vinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-methoxyphenyl vinyl ether, α-methylphenyl vinyl ether, β-methylisobutyl vinyl ether, β-chloroisobutyl vinyl ether, etc. (4) N Vinyl compounds such as N-vinylcarbazole, N-vinylpyrrolidone, N-vinylindole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylacetanilide, N-vinylethylacetamide, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam, N-vinylimidazole and the like.

  In the present invention, at least one of the cationically polymerizable monomers is preferably an oxetane compound, and the oxetane compound is preferably a compound having an oxetane ring substituted at the 2-position.

  The oxetane compound preferably used in the present invention will be described below.

<< Oxetane compound having an oxetane ring substituted at the 2-position >>
In the ink of the present invention, it is preferable to use an oxetane compound having at least one oxetane ring substituted at the 2-position represented by the following general formula (1) in the molecule.

In the general formula (1), R _{1 to} R ₆ each represent a hydrogen atom or a substituent. However, at least one of the groups represented by R _{3 to} R ₆ is a substituent.

In the general formula (1), examples of the substituent represented by R _{1 to} R ₆ include a fluorine atom, an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, or a butyl group). Etc.), a C1-C6 fluoroalkyl group, an allyl group, an aryl group (for example, a phenyl group, a naphthyl group, etc.), a furyl group, or a thienyl group. Moreover, these groups may further have a substituent.

<< Oxetane compound having one oxetane ring in the molecule >>
Further, among the above general formula (1), compounds having an oxetane ring represented by the following general formulas (2) to (5) are preferably used.

In the formula, R _{1 to} R ₆ represent a hydrogen atom or a substituent, R ₇ and R ₈ each represent a substituent, and Z each independently represents an oxygen or sulfur atom, or oxygen or sulfur in the main chain. The divalent hydrocarbon group which may contain an atom is represented.

In the general formula (2) to (5), the substituent represented by each of R ₁ to R ₆ are the same as the substituents each represented by a R ₁ to R ₆ in the general formula (1).

In the general formulas (2) to (5), the substituents represented by R ₇ and R ₈ are each an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, or a butyl group). ), An alkenyl group having 1 to 6 carbon atoms (for example, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-butenyl group, 2-butenyl group) Group or 3-butenyl group), aryl group (for example, phenyl group, naphthyl group, etc.), aralkyl group (for example, benzyl group, fluorobenzyl group, methoxybenzyl group, etc.), acyl group having 1 to 6 carbon atoms ( For example, a propylcarbonyl group, a butylcarbonyl group, a pentylcarbonyl group, etc.), an alkoxycarbonyl group having 1 to 6 carbon atoms (for example, an ethoxycarbonyl group, a propoxycarbonyl group). Group, butoxycarbonyl group etc.), represents the number 1-6 alkylcarbamoyl group having a carbon (e.g., propylcarbamoyl group, butyl pentylcarbamoyl group), alkoxy carbamoyl group (e.g., such as ethoxy carbamoyl group).

  In the general formulas (2) to (5), an oxygen or sulfur atom represented by Z or a divalent hydrocarbon group which may contain an oxygen or sulfur atom in the main chain is an alkylene group (for example, Ethylene group, trimethylene group, tetramethylene group, propylene group, ethylethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, etc.), alkenylene group (for example, vinylene group, propenylene) Group), alkynylene group (for example, ethynylene group, 3-pentynylene group, etc.), and the carbon atom of the aforementioned alkylene group, alkenylene group, alkynylene group may be replaced by an oxygen atom or a sulfur atom. .

Among the above substituents, R ₁ is preferably a lower alkyl group (eg, a methyl group, an ethyl group, a propyl group, etc.), and an ethyl group is particularly preferably used. R ₇ and R ₈ are preferably a propyl group, a butyl group, a phenyl group or a benzyl group, and Z is preferably a hydrocarbon group containing no oxygen or sulfur atom (an alkylene group, an alkenylene group, an alkynylene group, etc.). .

<< Compound with two or more oxetane rings in the molecule >>
Moreover, in this invention, the compound which has a 2 or more oxetane ring in a molecule | numerator as represented by following General formula (6), (7) can be used.

In formula, Z is synonymous with the group used in the said General formula (2)-(5), m represents 2, 3 or 4. R _{1 to} R ₆ are a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group), a fluoroalkyl group having 1 to 6 carbon atoms, An allyl group, an aryl group (for example, a phenyl group, a naphthyl group, etc.) or a furyl group is represented. However, in General formula (6), at least one of R < ₃ > -R < ₆ > is a substituent.

In the formula, R ₉ is selected from the group consisting of a linear or branched alkylene group having 1 to 12 carbon atoms, a linear or branched poly (alkyleneoxy) group, or the following general formulas (9), (10) and (11). Represents a divalent group.

  As an example of the branched alkylene group having 1 to 12 carbon atoms, an alkylene group represented by the following general formula (8) is preferably used.

In the formula, R ₁₀ represents a lower alkyl group (for example, a methyl group, an ethyl group, a propyl group, etc.).

In the formula, n represents 0 or an integer of 1 to 2000, and R ₁₂ represents an alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group). R ₁₁ represents an alkyl group having 1 to 10 carbon atoms (eg, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group). Group, nonyl group, etc.) or a group represented by the following general formula (12).

In the formula, j represents 0 or an integer of 1 to 100, and R ₁₃ represents an alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group). Group, octyl group, nonyl group, etc.).

In the formula, R ₁₄ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, etc.) , An alkoxy group having 1 to 10 carbon atoms (for example, methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group, etc.), halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), nitro Represents a group, a cyano group, a mercapto group, an alkoxycarbonyl group (for example, a methyloxycarbonyl group, an ethyloxycarbonyl group, a butyloxycarbonyl group, etc.) or a carboxyl group.

In the formula, R ₁₅ represents an oxygen atom, a sulfur atom, —NH—, —SO—, —SO ₂ —, —CH ₂ —, —C (CH ₃ ) ₂ —, or —C (CF ₃ ) ₂ —. Represents.

Preferred embodiments of the partial structure of the compound having an oxetane ring used in the present invention include, for example, in the above general formulas (6) and (7), R ₁ is a lower alkyl group (for example, methyl group, ethyl group, propyl group). Group) and the like, and particularly preferably an ethyl group. As R ₉ , a hexamethylene group or one in which R ₁₄ is a hydrogen atom in the general formula (10) is preferably used.

In the general formula (8), R ₁₀ is preferably an ethyl group, R ₁₂ and R ₁₃ are each a methyl group, and Z is a hydrocarbon group containing no oxygen or sulfur atom.

  Furthermore, as an example of the preferable aspect of the compound which has an oxetane ring based on this invention, the compound represented by following General formula (13) is mentioned.

In the formula, r is an integer of 25 to 200, and R ₁₆ represents an alkyl group having 1 to 4 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, etc.) or a trialkylsilyl group. R ₁ , R ₃ , R ₅ , and R ₆ have the same meanings as the substituents represented by R _{1 to} R ₆ in the general formula (1). However, at least one of R _{3 to} R ₆ is a substituent.

  Hereinafter, although the specific example of the compound which has the oxetane ring substituted by 2-position which concerns on this invention is shown as the exemplary compounds 1-15, this invention is not limited to these.

1: trans-3-tert-butyl-2-phenyloxetane 2: 3,3,4,4-tetramethyl-2,2-diphenyloxetane 3: di [3-ethyl (2-methoxy-3-oxetanyl)] Methyl ether 4: 1,4-bis (2,3,4,4-tetramethyl-3-ethyl-oxetanyl) butane 5: 1,4-bis (3-methyl-3-ethyloxetanyl) butane 6: di ( 3,4,4-trimethyl-3-ethyloxetanyl) methyl ether 7: 3- (2-ethyl-hexyloxymethyl) -2,2,3,4-tetramethyloxetane 8: 2- (2-ethyl-hexyl) Oxy) -2,3,3,4,4-pentamethyl-oxetane 9: 4,4'-bis [(2,4-dimethyl-3-ethyl-3-oxetanyl) methoxy] biphenyl 1 : 1,7-bis (2,3,3,4,4- pentamethyl - oxetanyl) heptane)
11: Oxetanyl silsesquioxane 12: 2-methoxy-3,3-dimethyloxetane 13: 2,2,3,3-tetramethyloxetane 14: 2- (4-methoxyphenyl) -3,3-dimethyloxetane 15 : Di (2- (4-methoxyphenyl) -3-methyloxetane-3-yl) ether According to the present invention, the synthesis of a compound having an oxetane ring substituted at least at the 2-position is carried out by referring to the documents described below. It can be synthesized for reference.

(1) Hu Xianming, Richard M. et al. Kellogg, Synthesis, 533-538, May (1995)
(2) A. O. Fitton, J .; Hill, D.C. Ejan, R.A. Miller, Synth. , 12, 1140 (1987)
(3) Toshiro Imai and Shinya Nishida, Can. J. et al. Chem. Vol. 59, 2503-2509 (1981)
(4) Nobujiro Shimizu, Shintaro Yamaoka, and Yuho Tsuno, Bull. Chem. Soc. Jpn. 56, 3853-3854 (1983)
(5) Walter Fisher and Cyril A.M. Grob, Helv. Chim. Acta. , 61, 2336 (1978)
(6) Chem. Ber. 101, 1850 (1968)
(7) “Heterocyclic Compounds with Three- and Four-membered Rings”, Part Two, Chapter IX, Interscience Publishers, John Wiley & Son, N
(8) Bull. Chem. Soc. Jpn. 61, 1653 (1988)
(9) Pure Appl. Chem. , A29 (10), 915 (1992)
(10) Pure Appl. Chem. , A30 (2 &amp; 3), 189 (1993)
(11) Japanese Patent Laid-Open No. 6-16804 (12) German Patent No. 1,021,858 (content in photocurable ink)
The content of the compound having an oxetane ring substituted at least at the 2-position according to the present invention in the actinic ray curable ink is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

(Combination of oxetane compound and other monomers)
In addition, the compound having an oxetane ring substituted at least at the 2-position according to the present invention may be used alone, or two types having different structures may be used in combination, and a photopolymerizable monomer described later. And photopolymerizable compounds such as polymerizable monomers can be used in combination. When used in combination, the mixing ratio is preferably adjusted so that the compound having an oxetane ring substituted at least at the 2-position is 10 to 98% by mass in the mixture, and other photopolymerizable monomers and polymerizations. It is preferable to adjust so that photopolymerizable compounds, such as a polymerizable monomer, may be 2 to 90 mass%.

<< Oxetane compound having a substituent only at the 3-position >>
In the present invention, the oxetane compound having a substituent at the 2-position and a conventionally known oxetane compound can be used in combination, and among them, an oxetane compound having a substituent only at the 3-position can be preferably used together.

  Here, as the oxetane compound having a substituent only at the 3-position, for example, known compounds introduced in JP-A Nos. 2001-220526 and 2001-310937 can be used.

  Examples of the compound having a substituent only at the 3-position include compounds represented by the following general formula (14).

In the general formula (14), 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 it is excellent in tackiness, low viscosity and excellent workability.

  An example of a compound having two oxetane rings includes a compound represented by the following general formula (15).

In the general formula (15), R ¹ is the same group as that in the general formula (14). 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 (16), (17) and (18) can also be mentioned.

In the general formula (16), 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 (17), 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 (18), 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 (19).

In General formula (19), 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.

Exemplary compound 1 is a compound in which R ¹ is an ethyl group and R ³ is a carboxyl group in the general formula (15). Exemplary compound 2 is a compound in which, in the general formula (15), R ¹ is an ethyl group, R ³ is the general formula (18), R ⁶ and R ⁷ are methyl groups, and n is 1.

In the compound having two oxetane rings, a preferred example other than the above compound is a compound represented by the following general formula (20). In the general formula (20), R ¹ has the same meaning as R ¹ in the general formula (14).

  An example of a compound having 3 to 4 oxetane rings is a compound represented by the following general formula (21).

In the general formula (21), R ¹ has the same meaning as R ¹ in the general formula (14). 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 the above A, 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.

  Further, examples of the compound having 1 to 4 oxetane rings other than those described above include compounds represented by the following general formula (22).

In the general formula (22), R ⁸ has the same meaning as R ⁸ in the general formula (19). 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.

  Preferred specific examples of the oxetane compound according to the present invention include exemplified compounds 4, 5, and 6 shown below.

  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. Specific examples of these compounds include the following exemplified compounds 7, 8, and 9.

  Next, the photoacid generator used in the present invention will be described.

  As the photoacid generator, for example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (for example, Organic Electronics Materials Study Group, “Organic Materials for Imaging”, Bunshin Publishing (1993)). (See pages 187-192, Technical Information Association, “Photocuring Technology”, see Photoacid Generators introduced in 2001).

  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. Those having a borate compound as a counter anion are preferred because of their high acid generating ability. Specific examples of the onium compound are shown below.

  Secondly, sulfonated products that generate sulfonic acid can be mentioned. Specific compounds are exemplified below.

  Thirdly, a halide that generates hydrogen halide can also be used.

  Fourthly, an iron allene complex can be mentioned.

  When coloring the ink according to the present invention, a colorant is added.

  As the colorant used in the present invention, conventionally known pigments and dyes can be used. Examples of the pigment include various chromatic organic pigments such as phthalocyanine, azo, quinacridone, dioxazine, and diketopyrrolopyrrole, inorganic pigments such as carbon black, titanium white, silica, mica, and zinc oxide. Is mentioned.

  As the organic pigment, those listed below can be used as appropriate. Examples of the yellow pigment include Pigment Yellow 1, Pigment Yellow 2, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 16, Pigment Yellow 17, Pigment Yellow 55, Pigment Yellow 73, and Pigment Yellow 74. Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 93, Pigment Yellow 95, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 109, Pigment Yellow 110, Pigment Yellow 114, Pigment Yellow 128, Pigment Yellow 138, Pigment Yellow 139, Pigment Yellow 150, pigment yellow 151, pigment yellow 154, Pigment Yellow 155 and Pigment Yellow 180, and the like.

  Examples of magenta pigments include, for example, Pigment Red 5, Pigment Red 7, Pigment Red 12, Pigment Red 48 (Ca), Pigment Red 48 (Mn), Pigment Red 57: 1, Pigment Red 57 (Sr), and Pigment Red 57: 2, Pigment Red 122, Pigment Red 123, Pigment Red 146, Pigment Red 168, Pigment Red 184, Pigment Red 202, Pigment Red 221, Pigment Red 238, Pigment Violet 19, and the like.

  Examples of cyan pigments include Pigment Blue 1, Pigment Blue 2, Pigment Blue 3, Pigment Blue 16, Pigment Blue 22, Pigment Blue 60, Pigment Blue 15: 2, Pigment Blue 15: 3, Pigment Blue 15: 4, and Bat. Blue 4 and Bat Blue 60 are listed.

  Also, by making the average particle diameter of the pigment particles in the range of about 25 to 350 nm, depending on the use of the printed material, it is sufficiently smaller than the wavelength of visible light, so that the printed material can be said to be sufficiently transparent if there is little scattering. Is given.

  When a dye is used as a colorant, unlike the case of using the above-mentioned pigment, it cannot be used in a state where there is no fading due to ultraviolet irradiation, and is somewhat fading. For this reason, when a dye is applied as the colorant of the ink, it is preferable to use a so-called azo metal-containing dye, which forms a complex with metal ions, because there is little fading due to light. However, if the level of fading is not a problem, even a general water-soluble dye can be used at least as an ink composition. On the premise of this, the dye species applicable in the sense of having a process color color are the following compounds.

  Examples of the yellow dye include Acid Yellow 11, Acid Yellow 17, Acid Yellow 23, Acid Yellow 25, Acid Yellow 29, Acid Yellow 42, Acid Yellow 49, Acid Yellow 61, Acid Yellow 71, Direct Yellow 12, Direct Yellow 24 Direct Yellow 26, Direct Yellow 44, Direct Yellow 86, Direct Yellow 87, Direct Yellow 98, Direct Yellow 100, Direct Yellow 130, Direct Yellow 132, Direct Yellow 142, and the like.

  Examples of the magenta red dye include Acid Red 1, Acid Red 6, Acid Red 8, Acid Red 32, Acid Red 35, Acid Red 37, Acid Red 51, Acid Red 52, Acid Red 80, Acid Red 85, and Acid. Red 87, Acid Red 92, Acid Red 94, Acid Red 115, Acid Red 180, Acid Red 254, Acid Red 256, Acid Red 289, Acid Red 315, Acid Red 317, Direct Red 1, Direct Red 4, Direct Red 13 , Direct Red 17, Direct Red 23, Direct Red 28, Direct Red 31, Direct Red 62, Direct Red 79, Direct Red 81, Die Kutoreddo 83, Direct Red 89, Direct Red 227, Direct Red 240, Direct Red 242 and Direct Red 243, and the like, and the like.

  Examples of cyan dyes include Acid Blue 9, Acid Blue 22, Acid Blue 40, Acid Blue 59, Acid Blue 93, Acid Blue 102, Acid Blue 104, Acid Blue 113, Acid Blue 117, Acid Blue 120, and Acid Blue 167. Acid Blue 229, Acid Blue 234, Acid Blue 254, Direct Blue 6, Direct Blue 22, Direct Blue 25, Direct Blue 71, Direct Blue 78, Direct Blue 86, Direct Blue 90, Direct Blue 106 and Direct Blue 199, etc. Is mentioned.

  In the ink of the present invention, in addition to the above-described constituent elements, a polymerization inhibitor, a surfactant, a leveling additive, a matting agent, a polyester resin for adjusting film physical properties, and a polyurethane resin as necessary. Vinyl resin, acrylic resin, rubber resin, and wax can be added.

  When a pigment is used as the colorant of the ink, the concentration of the pure pigment in the ink is generally in the range of 0.3 to 15% by mass with respect to the total amount of the ink. The coloring power of the pigment depends on the dispersion state of the pigment particles, but if it is in the range of about 0.3 to 1% by mass, it becomes a range that can be used as light-colored ink. On the other hand, if it is more than that, it gives a concentration used for general color coloring.

  The ink-jet ink used in the present invention has a viscosity of 10 to 500 mPa · s at 25 ° C. and 1 to 30 mPa · s when heated to 35 ° C. or higher using a pigment dispersion. Determine the composition ratio.

  By increasing the viscosity at room temperature, it is possible to prevent ink from penetrating into absorbent recording media, to reduce uncured monomers and to reduce odors, to suppress dot bleeding at the time of impact, and to improve image quality. The Further, since similar dots are formed between substrates having different surface tensions, similar image quality can be obtained. If it is less than 10 mPa · s, the effect of preventing bleeding is small, and if it is more than 500 mPa · s, there is a problem in the supply of ink liquid.

  Further, in order to obtain a stable light emitting property, the ink composition is preferably 1 to 30 mPa · s.

  When preparing the ink of the present invention, the raw materials to be used may be mixed in any order. However, in order to ensure stability during mixing, all the materials are adjusted in advance from neutral to basic. It is preferable to keep it. In mixing, it is preferable to stir quickly so as not to maintain a non-uniform state for a long time. When a pigment dispersion is used as the color material, it is preferable to perform further stirring after mixing so as not to impair the uniformity.

  Next, the image forming method of the present invention will be described.

In the image forming method using the ink of the present invention, actinic rays are irradiated after the ink composition is attached to a recording medium. Irradiation with generated light may be visible light irradiation or ultraviolet irradiation, and ultraviolet irradiation is particularly preferable. When performing ultraviolet irradiation, ultraviolet irradiation dose, 100 mJ / cm ² or more, preferably 500 mJ / cm ² or more, also, 10,000 / cm ² or less, preferably performed at 5,000 mJ / cm ² or less in the range . If it is the amount of ultraviolet irradiation within the range prescribed | regulated above, since a hardening reaction can fully be performed and it can also prevent that a coloring agent discolors by ultraviolet irradiation, it is advantageous. Examples of the ultraviolet irradiation include lamps such as metal halide lamps, xenon lamps, carbon arc lamps, chemical lamps, low pressure mercury lamps, and high pressure mercury lamps. For example, a commercially available product such as an H lamp, a D lamp, or a V lamp manufactured by Fusion System can be used.

  The metal halide lamp has a continuous spectrum as compared with a high-pressure mercury lamp (main wavelength is 365 nm), has high luminous efficiency in the range of 200 to 450 nm, and has a long wavelength range. Therefore, a metal halide lamp is suitable when a pigment is used as in the ink composition of the present invention.

  In the present invention, the total ink film thickness after the ink has landed on the recording material and cured by irradiation with actinic rays is preferably 2 to 20 μm. In the actinic ray curable inkjet recording in the screen printing field, the total ink film thickness currently exceeds 20 μm, but in the flexible packaging printing field where the recording material is often a thin plastic material, the recording material described above is used. In addition to the problem of curling and wrinkles, there is a problem that the entire printed matter is changed in its strain and texture.

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

  As the ink ejection conditions, it is preferable from the viewpoint of ejection stability that the recording head and ink are heated to 35 to 100 ° C. and ejected. Actinic radiation curable ink has a large viscosity fluctuation range due to temperature fluctuations, and the viscosity fluctuations directly affect the droplet size and droplet ejection speed, causing image quality degradation. It is necessary to keep. 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, it is preferable that the amount of droplets discharged from each nozzle is 2 to 15 pl. Originally, in order to form a high-definition image, it is necessary for the amount of droplets to be within this range, but when discharging with this amount of droplets, the above-described discharge stability becomes particularly severe. According to the present invention, even when the ink is ejected with a small droplet amount such as 2 to 15 pl, the ejection stability is improved and a high-definition image can be stably formed.

  In the image forming method of the present invention, it is preferable that the active light is irradiated for 0.001 to 2.0 seconds after ink landing, more preferably 0.001 to 1.0 as the active light irradiation condition. Seconds. In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.

  As a method for irradiating actinic rays, a basic method is disclosed in, for example, Japanese Patent Application Laid-Open No. 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 irradiating a recording unit with UV light by applying a collimated light source to a mirror surface provided on the side surface of the head unit is disclosed. Has been. Any of these irradiation methods can be used in the image forming method of the present invention.

  In addition, irradiation with actinic rays is divided into two stages. First, actinic rays are irradiated by the above-described method within 0.001 to 2.0 seconds after ink landing, and further, actinic rays are irradiated after all printing is completed. The method is also a preferred embodiment. By dividing the irradiation of actinic rays into two stages, it is possible to further suppress the shrinkage of the recording material that occurs during ink curing.

  In the present invention, it is also possible to use a light source in which the total power consumption of the light source for irradiating actinic rays is less than 1 kW · hr. Examples of the light source having a total power consumption of less than 1 kW · hr include, but are not limited to, a fluorescent tube, a cold cathode tube, and an LED. The total power consumption is the total amount of power required to drive and illuminate the light source.According to the present invention, even with a small amount of power as described above, the character quality is excellent, there is no color mixing, and a high-definition image is produced. Ink jet recording capable of very stable recording becomes possible.

  Next, the printed matter of the present invention will be described.

The printed matter of the present invention is characterized in that it is produced on a non-absorbent recording material using the image forming method of the present invention or the recording apparatus of the present invention. The term “non-absorbing” as used herein means that the ink composition (also simply referred to as ink) is not absorbed. In the present invention, the ink transfer amount in the Bristow method as described below is 0.1 ml / mm. ^{A material} that is less than ² and substantially 0 ml / mm ² is defined as a non-absorbent recording material.

The Bristow method referred to in the present invention is a method for measuring the liquid absorption behavior of paper and paperboard in a short time. TAPPI paper pulp test method no. It is measured according to the liquid absorptivity test method (Bristow method) of 51-87 paper or paperboard, and is expressed as an ink transfer amount (ml / m ² ) at a contact time of 40 milliseconds. In the above measurement method, pure water (ion exchange water) is used for the measurement, but in order to facilitate the determination of the measurement area, the present invention contains less than 2% water-soluble dye. May be.

  An example of a specific measurement method will be described below.

  As a method for measuring the amount of ink transfer, the recording medium is allowed to stand for 12 hours or more in an atmosphere of 25 ° C. and 50% RH, and then, for example, the Bristow test, which is a liquid dynamic absorbency tester manufactured by Kumagai Riki Kogyo Co., Ltd. Measure using machine II (pressurization type). The liquid used for measurement is a commercially available water-based ink-jet ink (for example, magenta ink) in order to increase the measurement accuracy, and the amount of ink transfer is measured by measuring the area of the magenta-stained portion on the recording medium after a specified contact time. Can be requested.

  As the non-absorbent recording material according to the present invention, various non-absorbable plastics and films used for so-called soft packaging can be used in addition to ordinary non-coated paper, coated paper, etc. For example, there are PET (polyethylene terephthalate) film, OPS (stretched polystyrene) film, OPP (stretched polypropylene) film, ONy (stretched nylon) film, PVC (polyvinyl chloride) film, PE film, and TAC film. As other plastics, polycarbonate, acrylic resin, ABS, polyacetal, PVA, rubbers and the like can be used. Moreover, it is applicable also to metals and glass. Among these recording materials, 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 base materials are not only susceptible to curling and deformation of the film due to curing shrinkage of the ink and heat generated during the curing reaction, but also the ink film is difficult to follow the shrinkage of the base material.

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 recording material. In the structure of the present invention, a high-definition image good for a wide range of recording materials such as an OPP film having a low surface energy, an OPS film, and a PET having a relatively large surface energy, such as a surface energy of 35 to 60 mJ / m ^2. The recording material is more preferably in the range of 40 to 60 mJ / m ² .

  In the present invention, it is more advantageous to use a long (web) recording material in terms of the cost of the recording material such as packaging cost and production cost, the production efficiency of the print, and the ability to cope with printing of various sizes. is there.

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

  The recording apparatus of the present invention will be described below with reference to the drawings as appropriate. Note that the recording apparatus of the drawings is merely one aspect of the recording apparatus of the present invention, and the recording apparatus of the present invention is not limited to this drawing.

  FIG. 1 is a front view showing a configuration of a main part of the recording apparatus of 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 recording material P. The platen unit 5 is provided with a planar heater so that the recording material P can be heated, and the recording material P can be heated to 40 to 80 ° C.

  The recording 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 recording material 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 recording material 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 drawing is shown on the assumption that the head carriage 2 houses the recording heads 3 of white (W), yellow (Y), magenta (M), cyan (C), black (K), and white (W). In practice, the number of colors of the recording head 3 housed in the head carriage 2 can be determined as appropriate.

  The recording head 3 discharges actinic ray curable ink (for example, ultraviolet curable ink) supplied by an ink supply unit (not shown) by the operation of a plurality of discharge units (not shown) provided therein. The ink is discharged from the outlet toward the recording material P. The ultraviolet curable ink ejected by the recording head 3 is composed of a coloring material, a polymerizable monomer, an initiator, and the like, and is a monomer associated with the initiator acting as a catalyst when irradiated with ultraviolet rays. It has the property of being cured by crosslinking and polymerization reactions.

  During the scanning in which the recording head 3 moves from one end of the recording material P to the other end of the recording material P in the Y direction in FIG. 1 by driving the head scanning means, a certain area (landing possible area) in the recording material P On the other hand, ultraviolet curable 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 the ultraviolet curable ink is discharged toward one landing possible region, the recording material P is appropriately moved from the front to the back in FIG. While performing scanning, the recording head 3 discharges the ultraviolet curable ink to the next landable area adjacent to the rearward direction in FIG.

  By repeating the above-described operation and ejecting the ultraviolet curable ink from the recording head 3 in conjunction with the head scanning means and the conveying means, an image composed of an aggregate of ultraviolet curable ink droplets is formed on the recording material 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 cold cathode tube, a black light, an LED (light emitting diode) and the like can be applied, and a strip-shaped metal halide lamp tube, a cold cathode tube, A mercury lamp tube or black light is preferred. In particular, a cold cathode tube and black light emitting ultraviolet light having a wavelength of 365 nm are preferable because they can prevent bleeding, control the dot diameter efficiently, and reduce wrinkles during curing. By using black light as the radiation source of the irradiation means 4, the irradiation means 4 for curing the ultraviolet curable ink can be produced at low cost.

  The irradiating means 4 is almost the largest one that can be set by the recording apparatus (ultraviolet curable ink jet printer) 1 among the landable areas in which the recording head 3 ejects the ultraviolet curable ink by one scan driven by the head scanning means. It has the same shape or a shape larger than the landable area.

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

  As described above, as a 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 recording material P. It is effective to increase the distance h2 between the portion 31 and the recording material 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 that a bellows structure 7 is provided between the recording head 3 and the irradiation means 4.

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

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example 1
<Preparation of ink composition set>
Ink composition sets 1 to 3 each having the configuration shown in Table 1 were prepared.

  The details of each abbreviation described in Table 1 are as follows.

K: Black ink C: Cyan ink M: Magenta ink Y: Yellow ink W: White ink Color material 1: C.I. I. pigment Black-7
Color material 2: C.I. I. pigment Blue-15: 3
Color material 3: C.I. I. pigment Red-57: 1
Color material 4: C.I. I. pigment Yellow-13
Coloring material 5: Titanium oxide (anatase type average particle size 0.20 μm)
* 1: Tetraethylene glycol diacrylate * 2: ε-caprolactam modified dipentaerythritol hexaacrylate * 3: Phenoxyethyl methacrylate * 4: Polyacrylic acid or polymethacrylic acid Irgacure 907: Ciba Geigy B-2: Polyacrylic Acid (Hibiswako 103, Wako Pure Chemical Industries)
B-4: Polymethacrylic acid (Durimer AC-30H, manufactured by Nippon Pure Chemicals Co., Ltd.)
<< Inkjet image forming method >>
Each ink composition set prepared above is loaded into the ink jet recording apparatus shown in FIG. 1 having a piezo ink jet nozzle that can selectively control the ejection of ink droplets, and has a width of 600 mm and a length of 1000 m shown in Table 2. The following image recording was continuously performed on each of the long recording materials. The recording material was heated to 50 ° C. by a planar heater installed in the platen section. 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 2 to 15 pl multi-sized dots could be ejected at a resolution of 720 dpi × 720 dpi (dpi represents the number of dots per 2.54 cm), and each ink was ejected continuously. After landing, 0.1 seconds later, curing treatment was performed under the irradiation conditions shown in Table 3. After recording, the total ink film thickness was measured and found to be in the range of 2.3 to 13 μm. The evaluation was performed in a place adjusted to a temperature of 23 ° C. and 40% RH.

  Here, the details of the abbreviations of the recording materials described in Table 2 are as follows.

OPP: oriented polypropylene
PET: Polyethylene terephthalate
Moreover, the detail of the irradiation light source of Table 2 is as follows.

Irradiation light source C: High-pressure mercury lamp (power consumption 1 kW or more / hour)
<Evaluation of inkjet recording image>
Each image recorded by the above image forming method was subjected to the following evaluations. In addition, each evaluation was performed about the sample after 1 m of the image recording continuously discharged.

(Evaluation of character quality)
6-point MS Mincho fonts are printed at Y, M, C, and K color target densities, the texture of the characters is magnified with a magnifying glass and visually observed, and character quality is evaluated according to the following criteria. The average rank was calculated.

◎: No roughness ○: Slight roughness appears △: Slightly visible, but it can be recognized as text, but it can be used at the last minute ×: Level that is severely fuzzy and characters are faint (useful for color mixing (bleeding) resistance)
Each adjacent color dot was enlarged with a magnifying glass, the degree of bleeding was visually observed, the color mixing resistance was evaluated according to the following criteria, and the average rank of each color was determined.

◎: Adjacent dot shape maintains a perfect circle and no blurring ○: Adjacent dot shape maintains an almost perfect circle and almost no blur △: Adjacent dot is slightly blurred and the dot shape is slightly displaced , The level that can be used at the last minute ×: the level where the adjacent dots are blurred and mixed and cannot be used (evaluation of gloss)
A solid image of each color of Y, M, C, and K was printed, the degree of gloss was visually observed, the gloss was evaluated according to the following criteria, and the average rank of each color was determined.

◎: The solid image portion is extremely uniform and glossy ○: The solid image is glossy, but slight surface irregularities are observed Δ: The solid image surface has irregularities and is a practically acceptable lower limit. Level x: Clear unevenness is observed on the surface of the solid image, and there is no gloss, and the quality is outside the practically acceptable limit. Table 3 shows each evaluation result obtained as described above.

  As is clear from Table 3, the level of image formation using the ink composition set of the present invention records a high-definition image with superior character quality, no color mixing, and good gloss compared to the comparative example. I was able to.

Example 2
Ink composition sets 4 to 8 having the configurations described in Table 4 and Table 5 were prepared.

  In addition, the detail of the compound abbreviation which is not described in the said Table 1 among each compound of Table 4 and Table 5 is as follows.

Compound 1: Di (2- (4-methoxyphenyl) -3-methyloxetane-3-yl) ether Compound 3: Epoxidized soybean oil (DAIMACS 300K, manufactured by Daicel Chemical Industries)
OXT-221: Aron Oxetane OXT-221, Toa Gosei PN-111: Ajisper PN-111, Ajinomoto Fine Techno Co., Ltd. CS5102: Nippon Soda Co., Ltd. CI7001: Nippon Soda Co., Ltd. B-3: Polyacrylic acid (Durimer AC- 10LP, manufactured by Nippon Pure Chemical Co., Ltd.)

<< Inkjet image forming method >>
Each of the prepared ink composition sets 4 to 8 was subjected to image formation using the irradiation conditions and recording materials described in Table 6 according to the apparatus and method described in Example 1.

  Here, the details of the abbreviations of the recording materials described in Table 6 are as follows.

OPP: oriented polypropylene
PET: Polyethylene terephthalate
Moreover, the detail of the irradiation light source of Table 6, and the irradiation method is as follows.

Irradiation light source A: Fluorescent lamp (special order product manufactured by Nippon Electric Co., Ltd., power consumption less than 1 kW / hour)
Irradiation method A: Irradiation with a linear light source from both ends of the recording head Irradiation light source B: Cold cathode tube (special order product manufactured by Hibeck, power consumption less than 1 kW / hour 308 nm)
Irradiation method B: 10 line light sources are irradiated from both ends of the recording head. Note that the film thickness was increased to 2.3 to 19.6 μm because white ink was used.

<Evaluation of inkjet recording image>
For each image recorded by the image forming method, character quality evaluation, color mixing (bleeding) resistance evaluation and gloss evaluation were performed in accordance with the method described in Example 1, and the obtained results are shown in Table 7. Show.

  As can be seen from Table 7, the level of image formation using the ink composition set of the present invention recorded a high-definition image having superior character quality, no color mixing, and good gloss compared to the comparative example. I was able to.

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 material

Claims (11)

Ink ejected by a recording head having at least one nozzle capable of selectively controlling ejection of ink droplets, which is cured by actinic rays and contains polyacrylic acid or polymethacrylic acid . The ink according to claim 1, comprising 0.1 to 10% by mass of the polyacrylic acid or polymethacrylic acid. The ink according to claim 1, comprising a radical polymerizable monomer and a radical polymerization initiator. The ink according to claim 1, comprising a cationically polymerizable monomer and a photoacid generator. The ink according to claim 4, wherein at least one of the cationic polymerizable monomers is an oxetane compound. The ink according to claim 5, wherein the oxetane compound is a compound having an oxetane ring substituted at the 2-position. An image forming method comprising: using the ink according to any one of claims 1 to 6; and ejecting the ink onto a recording material using a recording head, and then irradiating with active light to cure the ink. . The image forming method according to claim 7, wherein the actinic ray is an ultraviolet ray. 9. The image forming method according to claim 7, wherein the amount of ink droplets ejected from each nozzle of the recording head is 2 to 15 pl per ejection. A printed matter produced by the image forming method according to any one of claims 7 to 9, using a non-absorbent recording material. 11. A recording apparatus used for producing a printed matter according to claim 10, wherein the recording head and the ink are heated to 35 to 100 [deg.] C. to discharge the ink.

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