JP2006182971A - Ink for inkjet recording and lithographic printing plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink for inkjet recording which has high curing sensitivity and provides a good-quality image, to provide a lithographic printing plate which makes it possible to record an image with high sensitivity, high adhesiveness to a recording medium and high resistance to printing without blurring, and to provide a method for preparing the same. <P>SOLUTION: (i) The ink for inkjet recording curable by irradiation of radiation comprising at least one polymerizable compound and a color material further comprises at least one hydrophobic graft (co)polymer. (ii) The lithographic printing plate has a hydrophobic image containing the above-described ink for inkjet recording on a hydrophilic substrate. (iii) The method for preparing the lithographic printing plate comprises injecting the above-described ink for inkjet recording to a hydrophilic substrate and then curing the ink by irradiation of radiation to form a hydrophobic image, thereby preparing a lithographic printing plate which requires no development processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention is capable of forming a high-sensitivity, high-quality image, ink-jet recording ink having good storage stability, and development processing is unnecessary, has high printing durability, and high-quality image. The present invention relates to a lithographic printing plate capable of forming and a method for producing the same.

  As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type and a melt type thermal transfer method, an ink jet method and the like. The electrophotographic system requires a process of forming an electrostatic latent image on a photosensitive drum by charging and exposure, and there is a problem that the system becomes complicated and consequently the manufacturing cost becomes high. In addition, although the thermal transfer method is inexpensive, there are problems such as high running costs and waste materials due to the use of ink ribbons. On the other hand, since the inkjet method can easily and inexpensively create an image, it has been applied to various printing fields such as photographs, various printing, marking, and special printing such as a color filter. 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 the ink jet method. Specifically, phase change inkjet method using solid wax ink at room temperature, solvent-based inkjet method using ink mainly composed of fast-drying organic solvent, UV inkjet method that crosslinks with ultraviolet (UV) light after recording, etc. It is.
Among them, 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. Ink (see, for example, Patent Documents 1 and 2) is disclosed.
However, even when these inks are used, the volume shrinkage during ultraviolet curing is large, and it is impossible to form high-definition images on various recording materials.
For example, there is a cationic polymerization type ultraviolet curable ink (see, for example, Patent Document 3) in order to improve low shrinkage. However, curling and undulation of the recording material occurred, and it was not a satisfactory level as a printed matter.

Conventionally, PS plates having a structure in which a lipophilic photosensitive resin layer is provided on a hydrophilic support are widely used as lithographic printing plates, and mask exposure (surface exposure) and development are performed via a lith film. In addition, a method for producing a printing plate using a computer-to-plate (CTP) technique in which a laser beam is scanned in accordance with digitized image information, exposed, and developed has been developed and put on the market.
(For example, see Patent Document 4)
On the other hand, a method for ejecting ink on a hydrophilic support by a UV inkjet method and preparing a lithographic printing plate by ultraviolet curing has been recently proposed.
However, in photopolymer lithographic printing plates, the photosensitive layer is already a film, so the effect of shrinkage due to curing was small. And the printing durability deteriorated.

JP-A-62-200204 (especially page 3-4) JP 2000-504778 Gazette (especially the description of “Claims”) JP 2002-188025 A (especially page 2-7) JP2003-246818

  An object of the present invention is to provide an ink for ink jet recording which has a high curing sensitivity, a small volume shrinkage during ultraviolet curing, and gives a high-definition image. Another object of the present invention is to provide a lithographic printing plate capable of recording an image having no bleeding, high sensitivity, high adhesion to a recording medium, and high printing durability, and a method for producing the same. That is.

An object of the present invention is an ink for ink jet recording comprising at least one polymerizable compound and a coloring material, which is curable by irradiation with radiation, and further contains at least one graft (co) polymer. This is solved by the ink.
Further, the above-mentioned problem is that a lithographic printing plate having a hydrophobic image containing the above-described ink jet recording ink on the hydrophilic support, and radiation after the ink jet recording ink described above is ejected onto the hydrophilic support. This is solved by a lithographic printing plate preparation method characterized in that a hydrophobic image is formed by irradiating and curing to form a lithographic printing plate that does not require development treatment.
In a preferred embodiment of the present invention, the graft (co) polymer in the ink is (i) a graft (co) polymer containing a hydrophobic constituent component in the side chain, which is an acrylic ester or a methacrylic ester. At least one hydrophobic macromer comprising as a constituent unit at least one hydrophobic monomer selected from the group consisting of styrene, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride, and maleic imide, A graft (co) polymer containing at least one hydrophilic monomer as a monomer unit, or (ii) a graft (co) polymer containing a hydrophobic constituent in the main chain, wherein the acrylates are Methacrylic acid esters, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride The above graft (co) containing at least one hydrophobic monomer selected from the group consisting of an acid and maleic imide and at least one hydrophilic macromer containing at least one hydrophilic monomer as a constituent unit as a monomer unit A polymer is preferred.

  When the graft (co) polymer of the present invention is added to the polymerizable composition, the detailed reason is not clear, but due to the characteristics attributable to the graft polymer, the shrinkage during ink curing is alleviated and the substrate adhesion is improved. At the same time, the apparent curing sensitivity was improved. When the ink of the present invention was used for image formation of a lithographic printing plate, a lithographic printing plate having high printing durability was obtained. This is presumably because the physical strength of the cured film was improved and high printing durability was provided by the low shrinkage of the ink of the present invention and the formation of microphase separation caused by the graft polymer.

  The ink composition of the present invention is an ink for ink jet recording which contains at least one polymerizable compound and a coloring material and can be cured by irradiation with radiation, and further contains at least one graft (co) polymer. It is characterized by that. The term “radiation” as used in the present invention means α rays, γ rays, X rays, ultraviolet rays, visible rays, electron rays, etc., among which ultraviolet rays and electron rays, particularly ultraviolet rays.

(1) Graft (co) polymer The graft (co) polymer in the ink composition of the invention will be described.
“Graft (co) polymer” means a graft polymer or graft copolymer, and “graft polymer” is a polymer in which a block structure different from the main chain is bonded to the main chain as a side chain. The “graft copolymer” refers to those made of two or more monomers among the graft polymers. The synthesis of the graft (co) polymer is basically 1. 1. Polymerize the branch monomer from the trunk polymer. 2. Link the branch polymer to the trunk polymer. It can be divided into three methods (macromer method) in which a branch polymer is copolymerized with a trunk polymer.
Any of these three methods can be used to synthesize the graft (co) polymer of the present invention, but “3. Macromer method” is particularly excellent from the viewpoints of suitability for production and ease of synthesis. ing. The synthesis of graft (co) polymers using macromers is described in “New Polymer Experiments 2, Synthesis and Reaction of Polymers” edited by Kyoritsu Publishing Co., Ltd. 1995, edited by the Society of Polymer Science. It is also described in detail in Yuya Yamashita, et al. “Macromonomer Chemistry and Industry”, published in 1989.

  The graft (co) polymer used in the present invention is preferably (b) a graft (co) polymer having a hydrophobic constituent component in the main chain or side chain (hereinafter referred to as the specific hydrophobic graft ( A co) polymer or a specific hydrophobic graft polymer.), “(B-1) Graft (co) polymer having a hydrophobic component in the side chain” means any position on the side chain. This refers to a product in which hydrophobic constituent components are bonded. “(B-2) Graft (co) polymer having a hydrophobic constituent component in the main chain” means that the hydrophobic constituent component is directly in the main chain. Refers to a combination.

(B-1) Graft (co) polymer having a hydrophobic component on the side chain (b-1) Graft (co) polymer having a hydrophobic component on the side chain used in the present invention (hereinafter, The side chain-type specific hydrophobic graft (co) polymer is appropriately referred to as a graft (co) polymer having a macromer having a hydrophobic monomer as a basic unit as a side chain. In the present specification, the hydrophobic monomer means a water-insoluble monomer.
The side chain type specific hydrophobic graft (co) polymer is a polymer obtained by polymerizing a macromer having a hydrophobic monomer as a basic unit, or a macromer having a hydrophobic monomer as a basic unit and at least one other monomer. The composition molar ratio in the copolymer of the macromer having a hydrophobic monomer as a basic unit is preferably in the range of 100 to 5% from the viewpoint of oxygen resistance, and 90 to 5 % Is more preferable, and 80% to 5% is most preferable.
First, a macromer having a hydrophobic monomer as a basic unit (hereinafter, appropriately referred to as a hydrophobic macromer) will be described.

<Hydrophobic macromer>
Examples of hydrophobic constituents of the hydrophobic macromer used in the present invention include acrylic esters, methacrylic esters, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride, maleic imide, etc. Examples include those obtained by polymerizing one selected from known hydrophobic monomers, or those obtained by copolymerizing two or more. The hydrophobic macromer of the present invention is obtained by bonding a polymerizable group to the terminal of this hydrophobic constituent component.

  Specific examples of the acrylic esters include methyl acrylate, ethyl acrylate, (n- or i-) propyl acrylate, (n-, i-, sec- or t-) butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate , Dodecyl acrylate, chloroethyl acrylate, cyclohexyl acrylate, allyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, benzyl acrylate, methoxybenzyl acrylate, chlorobenzyl acrylate, hydroxybenzyl acrylate, hydroxyphenethyl acrylate, dihydroxyphenethyl acrylate, furfuryl Acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, hydro Examples include xylphenyl acrylate, chlorophenyl acrylate, sulfamoylphenyl acrylate, and 2- (hydroxyphenylcarbonyloxy) ethyl acrylate.

  Specific examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, (n- or i-) propyl methacrylate, (n-, i-, sec- or t-) butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, Dodecyl methacrylate, chloroethyl methacrylate, cyclohexyl methacrylate, allyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, benzyl methacrylate, methoxybenzyl methacrylate, chlorobenzyl methacrylate, hydroxybenzyl methacrylate, hydroxyphenethyl methacrylate, dihydroxyphenethyl methacrylate, furfuryl methacrylate , Tetrahydrofurfurylmethac Examples include relate, phenyl methacrylate, hydroxyphenyl methacrylate, chlorophenyl methacrylate, sulfamoylphenyl methacrylate, and 2- (hydroxyphenylcarbonyloxy) ethyl methacrylate.

  Specific examples of vinyl esters include vinyl acetate, vinyl butyrate, vinyl benzoate and the like.

  Specific examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, propyl styrene, cyclohexyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, methoxy styrene, dimethoxy styrene. Chlorostyrene, dichlorostyrene, bromostyrene, iodostyrene, fluorostyrene, carboxystyrene and the like.

The hydrophobic monomer may further have a substituent. As the substituent, a monovalent nonmetallic atomic group excluding hydrogen is used. Preferred examples include halogen atoms (-F, -Br, -Cl, -I), hydroxyl groups, alkoxy groups, aryloxy groups, mercapto groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, amino groups, N-alkylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkyl Carbamoyloxy group, N, N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy group, arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-aryl Acylamino group, ureido group, N ′ -Alkylureido group, N ', N'-dialkylureido group, N'-arylureido group, N', N'-diarylureido group, N'-alkyl-N'-arylureido group, N-alkylureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′-alkyl-N-arylureido group, N ′, N′-dialkyl-N-alkylureido group, N ′, N′-dialkyl- N-arylureido group, N′-aryl-N-alkylureido group, N′-aryl-N-arylureido group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl- N-arylureido group, N′-alkyl-N′-aryl-N-alkylureido group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino , Aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonyl Amino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl Group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (—SO ₃ H) and its conjugate base group (hereinafter referred to as sulfonate group), Al Coxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N -Alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonate group), dialkyl phosphono group (—PO ₃ (alkyl) ₂ ), diaryl a phosphono group _{(-PO 3 (aryl) 2)} , alkyl aryl phosphono group (-PO ₃ ( Lkyl) (aryl)), monoalkyl phosphono group (-PO ₃ H (alkyl)) and its conjugated base group (hereinafter referred to as alkyl phosphonophenyl group), monoaryl phosphono group (-PO ₃ H (aryl) ) And conjugated base groups thereof (hereinafter referred to as aryl phosphonate groups), phosphonooxy groups (—OPO ₃ H ₂ ) and conjugated base groups thereof (hereinafter referred to as phosphonateoxy groups), dialkylphosphonooxy groups ( -OPO ₃ (alkyl) _2), diaryl phosphonooxy group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphonooxy group (-OPO (alkyl) (aryl) ), monoalkyl phosphonooxy group (-OPO ₃ H (alkyl)) and its conjugated base group (hereinafter referred to as alkyl phosphonophenyl group), monoaryl Sufonookishi group (-OPO ₃ H (aryl)) and its conjugated base group (hereinafter referred to as aryl phosphite Hona preparative group), Moruhoruno group, a cyano group, a nitro group, an aryl group, an alkenyl group, an alkynyl group.

Specific examples of the alkyl group in these substituents include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, isopropyl group, isobutyl group, s-butyl group, t -Butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group and the like can be mentioned. Among these, a hydrogen atom, a methyl group, and an ethyl group are more preferable from the viewpoints of effects and availability. Specific examples of the aryl group include phenyl, biphenyl, naphthyl, tolyl 2, xylyl, mesityl, cumenyl, chlorophenyl, bromophenyl, chloromethylphenyl, hydroxyphenyl, methoxyphenyl, Ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylaminophenyl group, dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group , Ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, phenyl group, cyanophenyl group, sulfophenyl group, sulfonatophenyl group, phosphonophenyl , Can be exemplified phosphonophenyl phenyl group. Examples of the alkenyl group include vinyl group, 1-propenyl group, 1-butenyl group, cinnamyl group, 2-chloro-1-ethenyl group and the like. Examples of alkynyl group include ethynyl group, 1- A propynyl group, a 1-butynyl group, a trimethylsilylethynyl group, etc. are mentioned. Examples of G ₁ in the acyl group (G ₁ CO—) include hydrogen and the above alkyl groups and aryl groups.

  Of these substituents, more preferred are halogen atoms (—F, —Br, —Cl, —I), alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, N-alkylamino groups, N, N-dialkyls. Amino group, acyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, acylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, sulfo group, sulfonate group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group Group, N-arylsulfamoy Group, N-alkyl-N-arylsulfamoyl group, phosphono group, phosphonate group, dialkyl phosphono group, diaryl phosphono group, monoalkyl phosphono group, alkyl phosphonate group, monoaryl phosphono group, aryl phosphonate group Group, phosphonooxy group, phosphonatooxy group, aryl group, and alkenyl group.

  On the other hand, examples of the alkylene group in the substituted alkyl group include divalent organic residues obtained by removing any one of the hydrogen atoms on the alkyl group having 1 to 20 carbon atoms. Can be a straight chain having 1 to 12 carbon atoms, a branched chain having 3 to 12 carbon atoms, and a cyclic alkylene group having 5 to 10 carbon atoms. Preferable specific examples of the substituted alkyl group obtained by combining the substituent and the alkylene group include chloromethyl group, bromomethyl group, 2-chloroethyl group, trifluoromethyl group, methoxymethyl group, methoxyethoxyethyl group, allyl group. Oxymethyl group, phenoxymethyl group, methylthiomethyl, tolylthiomethyl group, ethylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group, N-cyclohexylcarbamoyloxyethyl group, N- Phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl group, 2-oxyethyl group, 2-oxypropyl group, carboxypropyl group, methoxycarbonylethyl group, allyloxy Carbonylbutyl group, chlorophenoxycarbonylmethyl group, carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-dipropylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, N-methyl-N- (sulfophenyl) ) Caravamoylmethyl group, sulfobutyl group, sulfonatobutyl group, sulfamoylbutyl group, N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfamoylpropyl group, N- Methyl-N- (phosphonophenyl) sulfamoyloctyl group, phosphonobutyl group, phosphonatohexyl group, diethylphosphonobutyl group, diphenylphosphonopropyl group, methylphosphonobutyl group, methylphosphonatobutyl group, tolylphospho Hexyl group, tolylphosphonatohexyl group, phosphonooxypropyl group, phosphonatoxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, p-methylbenzyl group, Cinnamyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group and the like can be mentioned.

  The preferred molecular weight of these macromers is 400 to 100,000, more preferably 1000 to 50,000, and particularly preferably 1500 to 20,000. Within the range of this molecular weight, the effect of the present invention can be exhibited without impairing the polymerizability with the copolymerization monomer forming the main chain.

<Monomer that forms the main chain>
In the graft (co) polymer having a hydrophobic constituent component in the side chain, monomers forming the main chain include amide group-containing monomers, acid group-containing monomers, and acid group-containing monomer alkalis. Known hydrophilic monomers such as metal salts, quaternary ammonium salt-containing monomers and hydroxyl group-containing monomers are preferred from the viewpoint of substrate adhesion. A graft polymer can be synthesized by copolymerizing one or more selected from these hydrophilic monomers with one or more hydrophobic macromers.

  Specific examples of the amide group-containing monomer include 2-acrylamide-2-methylpropanesulfonic acid, N, N-dimethylacrylamide, acrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, methacrylamide, N-methylol acrylamide etc. are mentioned.

  Examples of the acid group-containing monomer include methacrylic acid, acrylic acid, styrene sulfonic acid and the like. Examples of alkali metal salts of acid group-containing monomers include sodium salt of methacrylic acid, sodium salt of acrylic acid, sodium styrenesulfonate, sodium ethoxymethacrylate sulfonate, sodium ethoxyacrylate sulfonate, and mono-2-acryloyloxyethyl acid phosphate. And the sodium salt thereof.

  Examples of the quaternary ammonium base-containing monomer include hydroxyethyltrimethylammonium methacrylate methacrylate, hydroxypropyltrimethylammonium methacrylate methacrylate, and hydroxyethyltrimethylammonium chloride acrylate.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and 2,3-dihydroxypropyl methacrylate.

  In the present invention, the hydrophilicity of the main chain can be appropriately adjusted by copolymerizing a hydrophobic monomer in addition to the hydrophilic monomer as the main chain of the graft (co) polymer. Specific examples of the hydrophobic monomer include monomers described in the description of the hydrophobic macromer in the present specification. The introduction amount of the hydrophobic monomer in the main chain is preferably 0 to 50 mol%, more preferably 0 to 30 mol%.

As a weight average molecular weight of the graft (co) polymer which has a hydrophobic structural component in a side chain, 5000-1 million are preferable, More preferably, it is 10,000-500,000.
The content of the graft polymer having a hydrophobic constituent component in the side chain in the image recording layer is 10 to 90% by mass, and 15 to 80% by mass with respect to the total solid content of the image recording layer. Preferably, 20 to 70% by mass is more preferable. Within these ranges, the effects of the present invention that improve both sensitivity and stability over time can be obtained.

Specific examples of the graft (co) polymer having a hydrophobic component in the side chain include, but are not limited to, the following. In the specific example of the copolymer, the number attached to the parenthesis of the monomer unit represents the molar ratio of the monomer component.

(B-2) Graft (co) polymer having a hydrophobic constituent component in the main chain (b-2) Graft (co) polymer having a hydrophobic constituent component in the main chain (hereinafter referred to as “the main chain”) The main chain type specific hydrophobic graft (co) polymer is appropriately referred to as a macromer (hereinafter referred to as a hydrophilic macromer) having a hydrophobic monomer and at least one hydrophilic monomer as a basic unit. , And the composition molar ratio of the hydrophobic monomer in the copolymer is preferably in the range of 99 to 5% from the viewpoint of high sensitivity, and is preferably 97 to 20%. More preferably, it is in the range, and most preferably in the range of 95 to 30%.

<Hydrophobic monomer>
Hydrophobic monomers constituting the main chain type specific hydrophobic graft (co) polymer are acrylic esters, methacrylic esters, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride, maleic imide It selects from well-known hydrophobic monomers, such as.

  Specific examples of the acrylic esters include methyl acrylate, ethyl acrylate, (n- or i-) propyl acrylate, (n-, i-, sec- or t-) butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate , Dodecyl acrylate, chloroethyl acrylate, cyclohexyl acrylate, allyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, benzyl acrylate, methoxybenzyl acrylate, chlorobenzyl acrylate, hydroxybenzyl acrylate, hydroxyphenethyl acrylate, dihydroxyphenethyl acrylate, furfuryl Acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, hydro Examples include xylphenyl acrylate, chlorophenyl acrylate, sulfamoylphenyl acrylate, and 2- (hydroxyphenylcarbonyloxy) ethyl acrylate.

  Specific examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, (n- or i-) propyl methacrylate, (n-, i-, sec- or t-) butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, Dodecyl methacrylate, chloroethyl methacrylate, cyclohexyl methacrylate, allyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, benzyl methacrylate, methoxybenzyl methacrylate, chlorobenzyl methacrylate, hydroxybenzyl methacrylate, hydroxyphenethyl methacrylate, dihydroxyphenethyl methacrylate, furfuryl methacrylate , Tetrahydrofurfurylmethac Examples include relate, phenyl methacrylate, hydroxyphenyl methacrylate, chlorophenyl methacrylate, sulfamoylphenyl methacrylate, and 2- (hydroxyphenylcarbonyloxy) ethyl methacrylate.

Specific examples of vinyl esters include vinyl acetate, vinyl butyrate, vinyl benzoate and the like.
Specific examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, propyl styrene, cyclohexyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, methoxy styrene, dimethoxy styrene. Chlorostyrene, dichlorostyrene, bromostyrene, iodostyrene, fluorostyrene, carboxystyrene and the like.

The hydrophobic monomer may further have a substituent. As the substituent, a monovalent nonmetallic atomic group excluding hydrogen is used. Preferred examples include halogen atoms (-F, -Br, -Cl, -I), hydroxyl groups, alkoxy groups, aryloxy groups, mercapto groups, alkylthio groups, arylthio groups, alkyldithio groups, aryldithio groups, amino groups, N-alkylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkyl Carbamoyloxy group, N, N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyloxy group, alkylsulfoxy group, arylsulfoxy group, acylthio group, acylamino group, N-alkylacylamino group, N-aryl Acylamino group, ureido group, N ′ -Alkyl ureido group, N ', N'-dialkyl ureido group, N'-aryl ureido group, N', N'-diaryl ureido group, N'-alkyl-N'-aryl ureido group, N-alkyl ureido group, N-arylureido group, N′-alkyl-N-alkylureido group, N′-alkyl-N-arylureido group, N ′, N′-dialkyl-N-alkylureate group, N ′, N′-dialkyl -N-arylureido group, N'-aryl-N-alkylureido group, N'-aryl-N-arylureido group, N ', N'-diaryl-N-alkylureido group, N', N'-diaryl -N-arylureido group, N'-alkyl-N'-aryl-N-alkylureido group, N'-alkyl-N'-aryl-N-arylureido group, alkoxycarbonylamino , Aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonyl Amino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl Group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfo group (—SO ₃ H) and its conjugate base group (hereinafter referred to as sulfonate group), Al Coxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group, N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N -Alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group (hereinafter referred to as phosphonate group), dialkyl phosphono group (—PO ₃ (alkyl) ₂ ), diaryl a phosphono group _{(-PO 3 (aryl) 2)} , alkyl aryl phosphono group (-PO ₃ ( Lkyl) (aryl)), monoalkyl phosphono group (-PO ₃ H (alkyl)) and its conjugated base group (hereinafter referred to as alkyl phosphonophenyl group), monoaryl phosphono group (-PO ₃ H (aryl) ) And conjugated base groups thereof (hereinafter referred to as aryl phosphonate groups), phosphonooxy groups (—OPO ₃ H ₂ ) and conjugated base groups thereof (hereinafter referred to as phosphonateoxy groups), dialkylphosphonooxy groups ( -OPO ₃ (alkyl) _2), diaryl phosphonooxy group _{(-OPO 3 (aryl) 2)} , alkylaryl phosphonooxy group (-OPO (alkyl) (aryl) ), monoalkyl phosphonooxy group (-OPO ₃ H (alkyl)) and its conjugated base group (hereinafter referred to as alkyl phosphonophenyl group), monoaryl Sufonookishi group (-OPO ₃ H (aryl)) and its conjugated base group (hereinafter referred to as aryl phosphite Hona preparative group), Moruhoruno group, a cyano group, a nitro group, an aryl group, an alkenyl group, an alkynyl group.

Specific examples of the alkyl group in these substituents include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, isopropyl group, isobutyl group, s-butyl group, t -Butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-ethylhexyl group, 2-methylhexyl group, cyclopentyl group and the like can be mentioned. Among these, a hydrogen atom, a methyl group, and an ethyl group are more preferable from the viewpoints of effects and availability. Specific examples of the aryl group include phenyl, biphenyl, naphthyl, tolyl 2, xylyl, mesityl, cumenyl, chlorophenyl, bromophenyl, chloromethylphenyl, hydroxyphenyl, methoxyphenyl, Ethoxyphenyl group, phenoxyphenyl group, acetoxyphenyl group, benzoyloxyphenyl group, methylthiophenyl group, phenylthiophenyl group, methylaminophenyl group, dimethylaminophenyl group, acetylaminophenyl group, carboxyphenyl group, methoxycarbonylphenyl group , Ethoxyphenylcarbonyl group, phenoxycarbonylphenyl group, N-phenylcarbamoylphenyl group, phenyl group, cyanophenyl group, sulfophenyl group, sulfonatophenyl group, phosphonophenyl , Can be exemplified phosphonophenyl phenyl group. Examples of the alkenyl group include vinyl group, 1-propenyl group, 1-butenyl group, cinnamyl group, 2-chloro-1-ethenyl group and the like. Examples of alkynyl group include ethynyl group, 1- A propynyl group, a 1-butynyl group, a trimethylsilylethynyl group, etc. are mentioned. Examples of G ₁ in the acyl group (G ₁ CO—) include hydrogen and the above alkyl groups and aryl groups.

  Among these substituents, more preferred are halogen atoms (—F, —Br, —Cl, —I), alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, N-alkylamino groups, N, N-dialkyls. Amino group, acyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, acylamino group, formyl group, acyl group, carboxyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-alkylcarbamoyl group N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, sulfo group, sulfonate group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group Group, N-arylsulfamoy Group, N-alkyl-N-arylsulfamoyl group, phosphono group, phosphonate group, dialkyl phosphono group, diaryl phosphono group, monoalkyl phosphono group, alkyl phosphonate group, monoaryl phosphono group, aryl phosphonate group Group, phosphonooxy group, phosphonatooxy group, aryl group, and alkenyl group.

  On the other hand, examples of the alkylene group in the substituted alkyl group include divalent organic residues obtained by removing any one of the hydrogen atoms on the alkyl group having 1 to 20 carbon atoms. Can include linear alkylene groups having 1 to 12 carbon atoms, branched chains having 3 to 12 carbon atoms, and cyclic alkylene groups having 5 to 10 carbon atoms. Preferable specific examples of the substituted alkyl group obtained by combining the substituent and the alkylene group include chloromethyl group, bromomethyl group, 2-chloroethyl group, trifluoromethyl group, methoxymethyl group, methoxyethoxyethyl group, allyl group. Oxymethyl group, phenoxymethyl group, methylthiomethyl, tolylthiomethyl group, ethylaminoethyl group, diethylaminopropyl group, morpholinopropyl group, acetyloxymethyl group, benzoyloxymethyl group, N-cyclohexylcarbamoyloxyethyl group, N- Phenylcarbamoyloxyethyl group, acetylaminoethyl group, N-methylbenzoylaminopropyl group, 2-oxyethyl group, 2-oxypropyl group, carboxypropyl group, methoxycarbonylethyl group, allyloxy Carbonylbutyl group, chlorophenoxycarbonylmethyl group, carbamoylmethyl group, N-methylcarbamoylethyl group, N, N-dipropylcarbamoylmethyl group, N- (methoxyphenyl) carbamoylethyl group, N-methyl-N- (sulfophenyl) ) Caravamoylmethyl group, sulfobutyl group, sulfonatobutyl group, sulfamoylbutyl group, N-ethylsulfamoylmethyl group, N, N-dipropylsulfamoylpropyl group, N-tolylsulfamoylpropyl group, N- Methyl-N- (phosphonophenyl) sulfamoyloctyl group, phosphonobutyl group, phosphonatohexyl group, diethylphosphonobutyl group, diphenylphosphonopropyl group, methylphosphonobutyl group, methylphosphonatobutyl group, tolylphospho Hexyl group, tolylphosphonatohexyl group, phosphonooxypropyl group, phosphonatoxybutyl group, benzyl group, phenethyl group, α-methylbenzyl group, 1-methyl-1-phenylethyl group, p-methylbenzyl group, Cinnamyl group, allyl group, 1-propenylmethyl group, 2-butenyl group, 2-methylallyl group, 2-methylpropenylmethyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group and the like can be mentioned.

<Hydrophilic macromer>
The hydrophilic macromer is composed of an amide group-containing monomer, an acid group-containing monomer, an alkali metal salt of an acid group-containing monomer, a quaternary ammonium salt-containing monomer, and a hydroxyl group-containing monomer. It is a polymer containing 50 mol% or more of at least one hydrophilic monomer unit selected from the group consisting of polyethylene oxide, polypropylene oxide, polyester, and polyamide group-containing macromonomer. The hydrophilic segment more preferably contains 70 mol% or more of the hydrophilic monomer unit.
Specific examples of the amide group-containing monomer include acrylamide-t-butylsulfonic acid, N, N-dimethylacrylamide, acrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, methacrylamide, N -Methylol acrylamide, N-vinyl pyrrolidone, N-vinyl acetamide, etc. are mentioned.

  Examples of the acid group-containing monomer include methacrylic acid, acrylic acid, styrene sulfonic acid and the like. Examples of alkali metal salts of acid group-containing monomers include sodium salt of methacrylic acid, sodium salt of acrylic acid, sodium styrenesulfonate, sodium ethoxymethacrylate sulfonate, sodium ethoxyacrylate sulfonate, and mono-2-acryloyloxyethyl acid phosphate. And the sodium salt thereof.

  Examples of the quaternary ammonium base-containing monomer include hydroxyethyltrimethylammonium methacrylate methacrylate, hydroxypropyltrimethylammonium methacrylate methacrylate, and hydroxyethyltrimethylammonium chloride acrylate.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and 2,3-dihydroxypropyl methacrylate.

  Hydrophobic monomers used to adjust the hydrophilicity of the hydrophilic segment include acrylic esters, methacrylic acids, vinyl esters, styrenes, acrylonitrile, methacrylonitrile, maleic anhydride, maleic imide And the like, and known hydrophobic monomers.

  Specific examples of acrylic esters include methyl acrylate, ethyl acrylate, (n- or i-) propyl acrylate, (n-, i-, sec- or t-) butyl acrylate, chloroethyl acrylate, cyclohexyl acrylate, allyl Acrylate, benzyl acrylate, methoxybenzyl acrylate, chlorobenzyl acrylate, hydroxybenzyl acrylate, hydroxyphenethyl acrylate, dihydroxyphenethyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, hydroxyphenyl acrylate, chlorophenyl acrylate, sulfamoylphenyl acrylate, Examples include 2- (hydroxyphenylcarbonyloxy) ethyl acrylate It is.

  Specific examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, (n- or i-) propyl methacrylate, (n-, i-, sec- or t-) butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, Chloroethyl methacrylate, cyclohexyl methacrylate, allyl methacrylate, benzyl methacrylate, methoxybenzyl methacrylate, chlorobenzyl methacrylate, hydroxybenzyl methacrylate, hydroxyphenethyl methacrylate, dihydroxyphenethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, hydroxyphenyl methacrylate, chlorophenyl Methacrylate, sulfa Examples thereof include moylphenyl methacrylate and 2- (hydroxyphenylcarbonyloxy) ethyl methacrylate.

Specific examples of vinyl esters include vinyl acetate, vinyl butyrate, vinyl benzoate and the like.
Specific examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, propyl styrene, cyclohexyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, methoxy styrene, dimethoxy styrene. Chlorostyrene, dichlorostyrene, bromostyrene, iodostyrene, fluorostyrene, carboxystyrene and the like.

  Specific examples of the polyethylene oxide, polypropylene oxide, polyester, and polyamide group-containing macromonomer include the following. Moreover, you may combine these 2 types.

The preferred molecular weight of these macromers is in the range of 400 to 100,000, more preferred is 1000 to 50,000, and particularly preferred is 1500 to 20,000. Within the range of this molecular weight, the effects of the present invention can be exhibited without impairing the polymerizability with the copolymer monomer forming the trunk.
As a weight average molecular weight of the graft (co) polymer which has a hydrophobic structural component in a principal chain, 5000-1 million are preferable, More preferably, it is 10,000-500,000.
The content of the graft polymer having a hydrophobic constituent component in the main chain in the image recording layer is 10 to 90% by mass, and 15 to 80% by mass with respect to the total solid content of the image recording layer. Preferably, 20 to 70% by mass is more preferable. Within these ranges, the effects of the present invention that improve both sensitivity and stability over time can be obtained.
Specific examples of the graft (co) polymer having a hydrophobic constituent component in the main chain include the following, but the present invention is not limited to these specific examples.

(2) Components other than the hydrophobic graft (co) polymer in the ink (2-1) Polymerizable compound The ink of the present invention contains a polymerizable compound. Examples of the polymerizable compound include a radical polymerizable compound or a cationic polymerizable compound. Examples of the radical polymerizable compound include JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-7-231444 and the like. A photocurable material using a photopolymerizable composition described in JP-A-7-231444 is known, and as a cationic polymerizable compound, for example, a cationic polymerization type photocurable resin is known. Recently, photo-cationic polymerization type photocurable resins sensitized to a long wavelength region longer than visible light are also disclosed in, for example, JP-A-6-43633 and JP-A-8-324137.

(2-1-1) Radical polymerizable compound A radical polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and having at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. Any material may be used as long as it has a chemical form such as a monomer, oligomer or polymer. 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 the polymerizable compound 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 and maleic acid, and salts, esters and urethanes thereof. And radical polymerizable compounds such as amides, 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, Shinzo Yamashita, “Cross-linking agent handbook”, (1981 Taiseisha); Kato Kiyomi, “UV / EB curing handbook (raw material)” (1985, Polymer publication) ); Rad-Tech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products described in the above, or radically polymerizable or crosslinkable monomers known in the industry, Ligomers and polymers can be used.

(2-1-2) Cationic Polymerizable Compound As the cationic polymerizable compound, various known cationic polymerizable compounds (monomers) can be used. Examples thereof include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. An epoxy compound, a vinyl ether compound, an oxetane compound, etc. are mentioned. Examples of the cationically polymerizable compound of the present invention include oxetane compounds, epoxy compounds, vinyl ether compounds, or combinations thereof.

The (a) oxetane compound is a compound having an oxetane ring, and examples thereof include all known oxetane compounds as introduced in JP-A Nos. 2001-220526 and 2001-310937. In particular, a compound containing an oxetane ring represented by the following general formula (1) is preferable.

一般式（１）において、Ｒ₁〜Ｒ₆は、各々水素原子または置換基を表す。ただし、Ｒ₃〜Ｒ₆で表される基の少なくとも一つは置換基である。

In General formula (1), R < ₁ > -R < ₆ > represents a hydrogen atom or a substituent respectively. 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 and an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, 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.

Examples of the compound having one oxetane ring in the molecule include compounds represented by the following general formulas (2) to (5).

In the above general formulas (2) to (5), R _{1 to} R ₆ each represent a group having the same meaning as in the general formula (1), Z is independent, oxygen or sulfur atom, or oxygen or sulfur atom in the main chain Represents a divalent hydrocarbon group which may contain
In the above 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). Etc.), 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, 3-butenyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), aralkyl group (eg, benzyl group, fluorobenzyl group, methoxybenzyl group, etc.), acyl group having 1 to 6 carbon atoms (For example, propylcarbonyl group, butylcarbonyl group, pentylcarbonyl group, etc.), C1-C6 alkoxycarbonyl group (for example, ethoxycarbonyl group, propoxycarbonyl group) Butoxycarbonyl group), represents the number 1-6 alkylcarbamoyl group having a carbon (e.g., propylcarbamoyl group, butyl pentylcarbamoyl group), alkoxy carbamoyl group (e.g., 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. .

As the oxetane ring-containing compound used in the present invention, in the above general formulas (2) to (5), R ₁ is a lower alkyl group, particularly an ethyl group, and R ₇ and R ₈ are a propyl group, a butyl group, and a phenyl group. Or a benzyl group, wherein Z is a hydrocarbon group containing no oxygen or sulfur atom (an alkylene group, an alkenylene group, an alkynylene group, etc.). At this time, at least one group represented by R _{3 to} R ₆ is a substituent.
Examples of the compound having two or more oxetane rings in the molecule include compounds represented by the following general formulas (6) and (7).

In the general formulas (6) and (7), m represents 2, 3 or 4, and Z has the same meaning as Z represented by the general formulas (2) to (5).
R _{1 to} R ₆ each represent a group having the same meaning as in the general formula (1). However, in General formula (6), at least 1 of R < ₃ > -R < ₆ > is a substituent.
R ₉ is selected from the group consisting of linear or branched alkylene groups having 1 to 12 carbon atoms, linear or branched poly (alkyleneoxy) groups, or the following general formulas (9), (10) and (11). Represents a divalent group. The linear or branched alkylene group having 1 to 12 carbon atoms is preferably a group represented by the following general formula (8).

In the general formula (8), R ₁₀ represents a lower alkyl group such as a methyl group, an ethyl group, or a propyl group.

In the general formula (9), n is 0 or an integer of 1 to 2000, R ₁₁ is an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group). , A heptyl group, an octyl group, a nonyl group, or the like) or a group selected from the following general formula (12). 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, octyl group, nonyl group, etc.).

In the general formula (12), j is 0 or an integer of 1 to 100, R ₁₃ is an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, Hexyl group, heptyl group, octyl group, nonyl group, etc.).

In the general formula (10), R ₁₄ represents a hydrogen atom, 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 (eg, methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom) Etc.), a nitro 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 general formula (11), R ₁₅ represents an oxygen atom, a sulfur atom, NH, SO, SO ₂ , CH ₂ , C (CH ₃ ) ₂ or C (CF ₃ ) ₂ .

Preferred embodiments of the partial structure of the oxetane ring-containing compound 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, a methyl group, an ethyl group, a propyl group). And the like, 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, and in general formulas (9) and (12), R ₁₂ and R ₁₃ are each preferably a methyl group. However, in General Formula (6), at least one of the groups represented by R _{3 to} R ₆ is a substituent.

  Furthermore, examples of the compound having two or more oxetane rings in the molecule include compounds represented by the following general formula (13).

In the general formula (13), r is an integer of 25 to 200, R ₁₆ is an alkyl group or a trialkylsilyl group having 1 to 4 carbon atoms. R ₁ and R _{4 to} R ₆ have the same meanings as those in the general formula (1), and at least one of the groups represented by R _{3 to} R ₆ is a substituent.
Although the specific example of the compound containing the oxetane ring represented by General formula (1) based on this invention is shown in Table 1, this invention is not limited to these.

In addition, each of the above compounds can be easily synthesized mainly by the following scheme by referring to the following literature, including the method described in item 4 of "Catchball between polymer science and organic chemistry". The synthesis method is not limited to this.

1) Hu Xianming, Richard M. et al. Kellogg, Synthesis, 533-538, May (1995)
2) A. O. Fitton, J .; Hill, D.C. Ejane, 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. 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 & Sons, N
8) H.M. A. J. et al. Curless, “Synthetic Organic Photochemistry”, Plenum, New York (1984).
9) M.M. Braun, Nachr. Chem. Tech. Lab. 33, 213 (1985)
10) S.M. H. Schroeter, J.A. Org. Chem. , 34, 5, 1181 (1969)
11) D. R. Arnold, Adv. Photochem. 6,301 (1968)

Examples of the (b) epoxy compound include 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. In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

In the present invention, from the viewpoint of mutagenicity test (AMES), sensitization test, etc., particularly from the viewpoint of safety to the human body, epoxy compounds having an oxirane group include epoxidized fatty acid esters, epoxidized fatty acid glycerides. Particularly preferred is at least one of the following.
The epoxidized fatty acid ester and the epoxidized fatty acid glyceride are not particularly limited as long as an epoxy group is introduced into the fatty acid ester or fatty acid glyceride.
The epoxidized fatty acid ester is produced by epoxidizing an oleic acid ester, and examples thereof include methyl epoxy stearate, butyl epoxy stearate, octyl epoxy stearate and the like. Similarly, the epoxidized fatty acid glyceride is produced by epoxidizing soybean oil, linseed oil, castor oil and the like, and epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil and the like are used.

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

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

(2-1-3) Preferred polymerizable compound As the polymerizable compound of the present invention, (meth) acrylic monomers or prepolymers, epoxy monomers or prepolymers, urethane monomers or prepolymers are preferably used. More preferably, they are the following compounds.

  2-ethylhexyl-diglycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxybutyl acrylate, hydroxypivalate neopentyl glycol diacrylate, 2-acryloyloxyethyl phthalate, methoxy-polyethylene glycol acrylate, tetramethylol Methane triacrylate, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, dimethylol tricyclodecane diacrylate, ethoxylated phenyl acrylate, 2-acryloyloxyethyl succinic acid, nonylphenol EO adduct acrylate, modified glycerin triacrylate Bisphenol A diglycidyl ether acrylic acid adduct, modified bisphenol A diacrylate, phenoxy-polyethylene Glycol acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, bisphenol A PO adduct diacrylate, bisphenol A EO adduct diacrylate, dipentaerythritol hexaacrylate, pentaerythritol triacrylate tolylene diisocyanate urethane prepolymer, lactone Modified flexible acrylate, butoxyethyl acrylate, propylene glycol diglycidyl ether acrylic acid adduct, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, 2-hydroxyethyl acrylate, methoxydipropylene glycol acrylate, ditrimethylolpropane tetraacrylate, penta Erythritol triacrylate hexamethylene di Socia sulfonates urethane prepolymer, stearyl acrylate, isoamyl acrylate, isomyristyl acrylate, isostearyl acrylate.

  These acrylate compounds have lower skin irritation and sensitization (rash) than the polymerizable compounds conventionally used in UV curable inks, can relatively reduce viscosity, and provide stable ink ejection properties. Further, the polymerization sensitivity and the adhesion to the recording medium are also good. In the present invention, when the acrylate compound is used as the polymerizable compound, the content of the acrylate compound is, for example, 20 to 95% by mass, preferably 50%, based on the total mass of the ink for inkjet recording of the present invention. It is suitable to set it to -95 mass%, More preferably, it is 70-95 mass%.

In the present invention, the monomers listed as the polymerizable compounds described above are low in sensitization even with a low molecular weight, have high reactivity, low viscosity, and adhesion to a recording medium. Excellent.
In order to further improve sensitivity, bleeding, and adhesion to the recording medium, it is preferable to use the above monoacrylate in combination with a polyfunctional acrylate monomer or polyfunctional acrylate oligomer having a molecular weight of 400 or more, preferably 500 or more. It is preferable in terms of improving the performance. Furthermore, it is particularly preferable to use a monofunctional, bifunctional, or trifunctional or higher polyfunctional monomer in combination. While maintaining safety, the sensitivity, bleeding, and adhesion to the recording medium can be further improved. As the oligomer, an epoxy acrylate oligomer and a urethane acrylate oligomer are particularly preferable.

When recording on a flexible recording medium such as a PET film or PP film, the combination of a monoacrylate selected from the above compound group and a polyfunctional acrylate monomer or polyfunctional acrylate oligomer gives the film flexibility and adhesion. It is preferable because the film strength can be increased while improving the properties. As monoacrylate, stearyl acrylate, isoamyl acrylate, isomystil acrylate, and isostearyl acrylate have high sensitivity and low shrinkage to prevent curling, and are preferable in terms of prevention of bleeding, odor of printed matter, and cost reduction of irradiation device. .
In addition, methacrylate has better skin irritation than acrylate.
Of the above-mentioned compounds, when alkoxy acrylate is used in an amount of less than 70% by mass and the balance is acrylate, it is preferable because it has good sensitivity, bleeding characteristics and odor characteristics.

(2-1-4) Addition amount of polymerizable compound The addition amount of the polymerizable compound of the present invention is, for example, 1 to 97% by mass with respect to the total mass of the ink jet recording ink of the present invention, and more preferably. Is 30-95 mass%.

(2-2) Color Material The color material of the present invention is not particularly limited, but a pigment excellent in weather resistance is preferable, and any known color material such as a soluble dye and an oily dye can be used. Conventionally, a general dye could not be used as a coloring material that can be used in ink jet recording ink. This is because the dye functions as a polymerization inhibitor in the polymerization reaction, so that there is a problem that the sensitivity of radiation is lowered. However, since the amount of active species generated in the polymerization initiation system of the present invention increases, such a coloring material can also be used.
Although it does not necessarily limit as a coloring material of this invention, For example, the organic or inorganic pigment of the following number described in a color index can be used.

  That is, as red or magenta pigment, Pigment Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, 53 : 1, 57: 1, 57: 2, 58: 4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 104, 108, 112, 122, 123, 144 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36, blue or cyan pigments include Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16 17-1, 22, 27, 28, 29, 36, 60, as green pigment, Pigment Green 7, 26, 36, 50, as yellow pigment, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, Pigment Black 7, 28, 26 as the black pigment, and Pigment White 6, 18, 21, etc. as the white pigment can be used according to the purpose.

The color material of the present invention needs to be appropriately dispersed in the ink after being added to the ink for inkjet recording of the present invention. For dispersion of the color material, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, or a paint shaker can be used.
It is also possible to add a dispersant when dispersing the color material. The type of the dispersant is not particularly limited, but a polymer dispersant is preferably used, and examples of the polymer dispersant include Solsperse series manufactured by Zeneca. 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 coloring material of the present invention.
The coloring material may be added directly to the ink jet recording ink of the present invention, but may be added in advance to a dispersion medium such as a solvent or a polymerizable compound according to the present invention in order to improve dispersibility. In order to avoid the deterioration of the solvent resistance when the solvent remains in the cured image and the problem of VOC (Volatile Organic Compound) of the remaining solvent, the coloring material is added to the polymerizable compound of the present invention. It is preferable to do. Further, as the polymerizable compound to be used, it is preferable in view of dispersion suitability to select a monomer having the lowest viscosity.

The average particle diameter of the color material particles of the present invention is, for example, 0.08 to 0.5 μm, preferably 0.1 to 0.45 μm, and more preferably 0.15 to 0.4 μm. . The maximum particle size of the color material is, for example, 0.3 to 10 μm, preferably 0.3 to 3 μm. It is appropriate to select the pigment, the dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so that the maximum particle size is obtained. 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.
The color material of the present invention is contained in an amount of, for example, 1 to 10% by mass, preferably 2 to 8% by mass, based on the total ink mass.

(2-3) Polymerization initiator A polymerization initiator may be added to the ink composition of the invention. As the polymerization initiator, a radical polymerization initiator and a cationic polymerization initiator can be used.
(2-3-1) Radical polymerization initiator Preferred radical polymerization initiators that can be used in the present invention include (a) aromatic ketones, (b) aromatic onium salt compounds, (c) organic peroxides, ( d) thio compound, (e) hexaarylbiimidazole compound, (f) ketoxime ester compound, (g) borate compound, (h) azinium compound, (i) metallocene compound, (j) active ester compound, (k) Examples include compounds having a carbon halogen bond, and (l) alkylamine compounds. These radical polymerization initiators may be used alone or in combination with the above compounds (a) to (l). More preferable examples include aromatic iodonium salts, aromatic diazonium salts, titanocene compounds, and trihalomethyl-S-triazine compounds. The radical polymerization initiator in the present invention is preferably used alone or in combination of two or more.

(2-3-2) Cationic Polymerization Initiator As a preferred cationic polymerization initiator (photoacid generator) that can be used in the present invention, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used. (See Organic Electronics Materials Study Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), pages 187-192). Examples of the cationic polymerization initiator 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 — salts of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, and phosphonium are listed. be able to. Secondly, sulfonated products that generate sulfonic acid can be mentioned. Thirdly, a halide that generates hydrogen halide can also be used. Fourthly, an iron allene complex can be mentioned.

  The polymerization initiator in the present invention is suitably used alone or in combination of two or more. These radical polymerization initiators are contained in an amount of 0.01 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the polymerizable compound of the present invention. Further, the polymerization initiator of the present invention is 200: 1 to 1: 200, preferably 50: 1 to 1:50, more preferably, in a mass ratio of polymerization initiator: sensitizing dye to the above sensitizing dye. Is suitably included in the polymerization initiation system in an amount of 20: 1 to 1: 5.

(2-4) Sensitizing Dye A sensitizing dye may be added to the ink for inkjet recording of the present invention in order to absorb specific radiation and promote decomposition of the polymerization initiator. A sensitizing dye absorbs specific radiation and enters an electronically excited state. The sensitizing dye in an electronically excited state comes into contact with the polymerization initiator, and effects such as electron transfer, energy transfer, and heat generation occur. As a result, the polymerization initiator undergoes a chemical change and decomposes to generate radicals, acids or bases.
Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines ( For example, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, squalium) ), Coumarins (eg 7-diethylamino-4-methylcoumarin).

More preferable examples of the sensitizing dye include compounds represented by the following general formulas (IX) to (XIII).

(In the formula (IX), A1 represents a sulfur atom or NR ^50, R ⁵⁰ represents an alkyl group or an aryl group, L ² is formed a basic nucleus of the dye together with adjacent A ² and adjacent carbon atoms R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁵¹ and R ⁵² may be bonded to each other to form an acidic nucleus of the dye. W represents an oxygen atom or a sulfur atom.)

(In the formula (X), Ar ¹ and Ar ² each independently represent an aryl group and are linked via a bond with —L ³ —, where L ³ represents —O— or —S—. W has the same meaning as that shown in formula (IX).)

(In the formula (XI), A ₂ represents a sulfur atom or NR ⁵⁹ , L ⁴ represents a nonmetallic atomic group that forms a basic nucleus of the dye in combination with adjacent A ₂ and a carbon atom, R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a monovalent nonmetallic atomic group, and R ⁵⁹ represents an alkyl group or an aryl group.)

(In Formula (XII), A ³ and A ⁴ each independently represent —S— or —NR ⁶² — or —NR ⁶³ —, wherein R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted alkyl group, substituted or represents an unsubstituted aryl group, L to ^5, L ⁶ are each independently, and in cooperation with the adjacent a ^3, A4 ^及 beauty adjacent carbon atoms represent a non-metallic atomic group forming a basic nucleus of a dye , R ⁶⁰ and R ⁶¹ are each independently a hydrogen atom or a monovalent non-metallic atomic group, or can be bonded to each other to form an aliphatic or aromatic ring.)

(In the formula (XIII), R ⁶⁶ represents an aromatic ring or a hetero ring which may have a substituent, and A ⁵ represents an oxygen atom, a sulfur atom or —NR ⁶⁷ —. R ⁶⁴ , R ⁶⁵ and R ⁶⁷ each independently represents a hydrogen atom or a monovalent non-metallic atomic group, and R ⁶⁷ and R ⁶⁴ , and R ⁶⁵ and R ⁶⁷ may be bonded to each other to form an aliphatic or aromatic ring. it can.)

Preferable specific examples of the compounds represented by the general formulas (IX) to (XIII) include those shown below.

(2-5) Co-sensitizer In the present invention, the co-sensitizer has functions such as further improving the sensitivity of the sensitizing dye to radiation or suppressing the inhibition of polymerization of the polymerizable compound by oxygen.
Examples of such co-sensitizers include amines such as MR Sander et al., “Journal of Polymer Society”, Vol. 10, page 3173 (1972), Japanese Examined Patent Publication No. 44-20189, Japanese Patent Laid-Open No. 51-82102. Publication, JP 52-134692, JP 59-138205, JP 60-84305, JP 62-18537, JP 64-33104, Research Disclosure 33825 Specifically, triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like can be mentioned.

  Other examples of co-sensitizers include thiols and sulfides, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, and JP-A-56 And the like. Specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzoimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene. Etc.

  Other examples include amino acid compounds (eg, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (eg, tributyltin acetate), and hydrogen described in Japanese Patent Publication No. 55-34414. Donors, sulfur compounds described in JP-A-6-308727 (eg, trithiane), phosphorus compounds described in JP-A-6-250387 (diethylphosphite, etc.), Si-- described in Japanese Patent Application No. 6-191605 H, Ge-H compound, etc. are mentioned.

(2-6) Other components Other components can be added to the ink for ink jet recording of the present invention, if necessary. Examples of other components include a polymerization inhibitor, a solvent, and a cationic polymerizable monomer.
The polymerization inhibitor can be added from the viewpoint of improving the storage stability. In addition, the ink for ink jet recording of the present invention is preferably ejected by heating and lowering the viscosity in the range of 40 to 80 ° C., and a polymerization inhibitor is preferably added to prevent clogging of the head due to thermal polymerization. The polymerization inhibitor is preferably added in an amount of 200 to 20000 ppm based on the total amount of the ink for inkjet recording of the present invention. Examples of the polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cuperon Al.

In view of the fact that the ink for ink jet recording used in the present invention is a radiation curable ink, it is preferable not to contain a solvent so that it can react quickly and be cured immediately after ink landing. However, a predetermined solvent can be included as long as it does not affect the curing speed of the ink. In the present invention, an organic solvent or water can be used as the solvent. In particular, an organic solvent can be added in order to improve the adhesion to a recording medium (support such as paper). The addition of an organic solvent is effective because the VOC problem can be avoided. The amount of the organic solvent is, for example, in the range of 0.1 to 5% by mass, preferably 0.1 to 3% by mass, with respect to the total mass of the ink for inkjet recording of the present invention.
As a means for preventing sensitivity deterioration due to the light-shielding effect of the ink coloring material, in addition to the combination of a cationic polymerizable compound and a cationic polymerization initiator, and a combination of a radical polymerizable compound and a radical polymerization initiator, these polymerizable compounds and A radical-cation hybrid type curable ink may be used in combination with a polymerization initiator.

  In addition, a known compound can be added to the ink for ink jet recording of the present invention as necessary. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes and the like are appropriately selected and added. be able to. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to contain a tackifier that does not inhibit the polymerization. Specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, pages 5 to 6 (for example, (meth) acrylic acid and an alcohol having an alkyl group having 1 to 20 carbon atoms). An ester, a copolymer of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer of an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms), and polymerizability. Examples thereof include a low molecular weight tackifying resin having an unsaturated bond.

(2-7) Properties of inkjet recording ink As described above, the inkjet recording ink of the present invention contains a colorant, a polymerizable compound, and optionally a polymerization initiation system. These components are 1 to 10% by mass, preferably 2 to 8% by mass, and 1 to 97% by mass of the polymerizable compound, preferably 3 to 3% by mass with respect to the total mass of the inkjet recording ink. 95% by mass and the polymerization initiation system is contained in an amount of 0.01 to 20% by mass, preferably 0.1 to 20% by mass, and the total mass% of each component is 100% by mass. Is appropriate.
The obtained ink for inkjet recording has a viscosity of, for example, 7 to 30 mPa · s, preferably 7 at a temperature at the time of ejection (for example, 40 to 80 ° C., preferably 25 to 30 ° C.) in consideration of ejection properties. It is preferably ˜20 mPa · s. For example, the viscosity of the ink for inkjet recording of the present invention at room temperature (25 to 30 ° C.) is 35 to 500 mPa · s, preferably 35 to 200 mPa · s. The composition ratio of the ink for inkjet recording of the present invention is preferably adjusted as appropriate so that the viscosity is in the above range. By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be avoided, and uncured monomers and odors can be reduced. Furthermore, ink bleeding at the time of ink droplet landing can be suppressed, and as a result, the image quality is improved.

  The surface tension of the ink for inkjet recording of the present invention is, for example, 20 to 30 mN / m, preferably 23 to 28 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and non-coated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and the wettability is preferably 30 mN / m or less.

(3) Inkjet recording method and apparatus An inkjet recording method and an inkjet recording apparatus that can be suitably employed in the present invention will be described below.
(3-1) Inkjet recording method The present invention is a method in which the ink jet recording ink is jetted onto a support (recording material), the ink landed on the support is irradiated with radiation, and the ink is cured to form an image. Provide a method of forming. That is, the present invention
(a) applying the ink jet recording ink onto a support;
(b) Radiation having a peak wavelength of 200 to 600 nm, preferably 300 to 450 nm, more preferably 350 to 420 nm in the ink jet recording ink, 2000 mJ / cm ² or less, preferably 10 to 2000 mJ / cm ² , more preferably, 20~1000mJ / cm ² and even more preferably, a step of curing the inkjet ink by irradiating at an output of 50 to 800 mJ / cm ^2; and
(c) a step in which the cured ink for ink jet recording forms an image on a support,
Relates to a method comprising:

Furthermore, the ink jet recording method of the present invention will be described by taking as an example a method for preparing a lithographic printing plate including injecting an ink jet recording ink onto the lithographic printing plate to form an image.
The lithographic printing plate of the present invention has a hydrophilic support and a hydrophobic image formed on the hydrophilic support. This lithographic printing plate production method comprises the following steps:
(1) a step of ejecting the inkjet recording ink of the present invention onto the hydrophilic support; and
(2) a step of irradiating the surface of the hydrophilic support on which the ink has been ejected to cure the ink, thereby forming a hydrophobic image formed by curing the ink on the hydrophilic support;
And have.

(3-1-1) Lithographic printing plate Here, the lithographic printing plate has a support and an image formed on the support.
Conventionally, so-called PS plates having a configuration in which a lipophilic photosensitive resin layer is provided on a hydrophilic support have been widely used as lithographic printing plates. As a method for producing the PS plate, a desired printing plate is usually obtained by performing mask exposure (surface exposure) through a lith film and then dissolving and removing the non-exposed portion. However, in recent years, digitization techniques for electronically processing, storing, and outputting image information using a computer have become widespread, and a new image output method corresponding to the technique has been demanded. In particular, Computer-to-Plate (CTP) technology has been developed that scans highly-preferred light such as laser light according to digitized image information without using a lithographic film, and directly produces printing plates. Yes.

As a method for obtaining a lithographic printing plate that enables such scanning exposure, a method of directly producing a lithographic printing plate with an ink jet recording ink can be mentioned. This is because the ink is ejected onto a support, preferably a hydrophilic support by an ink jet method or the like, and this is exposed to radiation, whereby the ink jet recording ink portion is exposed to form a desired image (preferably, A printing plate having a hydrophobic image) is obtained. An ink jet recording ink suitable for such a method is the ink jet recording ink of the present invention.
The support (recording medium) on which the ink jet recording ink of the present invention is ejected is not particularly limited as long as it is a dimensionally stable plate-like support. The support is preferably a hydrophilic support. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. Preferable supports include a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a known material can be used as appropriate.

The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm.
Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Also, a transfer method in which the uneven shape is transferred with a roll provided with unevenness in the aluminum rolling step may be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.
The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is, but for further improvement in adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation and the like. If necessary, the surface of the anodized film described in JP-A-2001-253181 and JP-A-2001-322365 may be enlarged or sealed, and immersed in an aqueous solution containing a hydrophilic compound. A hydrophilic treatment or the like can be appropriately selected and performed. Of course, these enlargement processing and sealing processing are not limited to those described above, and any conventionally known method can be performed.

[Sealing treatment]
Sealing treatment includes vapor sealing, single treatment with zirconic fluoride, treatment with an aqueous solution containing an inorganic fluorine compound such as treatment with sodium fluoride, vapor sealing with addition of lithium chloride, sealing with hot water. Hole processing is also possible.
Of these, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and sealing treatment with hot water are preferable. Each will be described below.

<Sealing treatment with an aqueous solution containing an inorganic fluorine compound>
As the inorganic fluorine compound used for the sealing treatment with an aqueous solution containing an inorganic fluorine compound, a metal fluoride is preferably exemplified.
Specifically, for example, sodium fluoride, potassium fluoride, calcium fluoride, magnesium fluoride, sodium fluoride zirconate, potassium fluoride zirconate, sodium fluoride titanate, potassium fluoride titanate, zircon fluoride Ammonium acid, ammonium fluoride titanate, potassium fluoride titanate, fluorinated zirconate, fluorinated titanate, hexafluorosilicic acid, nickel fluoride, iron fluoride, phosphor fluoride, ammonium fluoride phosphate It is done. Of these, sodium fluorinated zirconate, sodium fluorinated titanate, fluorinated zirconic acid, and fluorinated titanic acid are preferable.

The concentration of the inorganic fluorine compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, from the viewpoint of sufficiently sealing the micropores of the anodized film. Further, in terms of stain resistance, it is preferably 1% by mass or less, and more preferably 0.5% by mass or less.
It is preferable that the aqueous solution containing an inorganic fluorine compound further contains a phosphate compound. When the phosphate compound is contained, the hydrophilicity of the surface of the anodized film is improved, so that on-machine developability and stain resistance can be improved.

Suitable examples of the phosphate compound include phosphates of metals such as alkali metals and alkaline earth metals.
Specifically, for example, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, dihydrogen phosphate Potassium, dipotassium hydrogen phosphate, calcium phosphate, sodium ammonium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, hydrogen phosphate Disodium, lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid, ammonium phosphotungstate, sodium phosphotungstate, ammonium phosphomolybdate, sodium phosphomolybdate, sodium phosphite , Tripolyphosphate Potassium, and sodium pyrophosphate. Of these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.

The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. Is preferred.
The concentration of the phosphate compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, from the viewpoint of improving on-press developability and stain resistance. Further, in terms of solubility, it is preferably 20% by mass or less, and more preferably 5% by mass or less.
The ratio of each compound in the aqueous solution is not particularly limited, but the inorganic fluorine compound and phosphate compound

The mass ratio of the product is preferably 1/200 to 10/1, and more preferably 1/30 to 2/1.
The temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower.
The aqueous solution preferably has a pH of 1 or more, more preferably has a pH of 2 or more, preferably has a pH of 11 or less, and more preferably has a pH of 5 or less.
The method for sealing with an aqueous solution containing an inorganic fluorine compound is not particularly limited, and examples thereof include an immersion method and a spray method. These may be used alone or in combination, or may be used in combination of two or more.
Of these, the dipping method is preferred. When the treatment is performed using the dipping method, the treatment time is preferably 1 second or longer, more preferably 3 seconds or longer, and preferably 100 seconds or shorter, and 20 seconds or shorter. More preferred.

<Sealing treatment with water vapor>
Examples of the sealing treatment with water vapor include a method of bringing pressurized or normal pressure water vapor into contact with the anodized film continuously or discontinuously.
The temperature of the water vapor is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 105 ° C. or lower.
The water vapor pressure is preferably in the range (1.008 × 10 ^{5 to} 1.043 × 10 ⁵ Pa) from (atmospheric pressure−50 mmAq) to (atmospheric pressure + 300 mmAq).
Further, the time for which the water vapor is contacted is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, more preferably 20 seconds or shorter.

<Sealing treatment with hot water>
Examples of the sealing treatment with water vapor include a method in which an aluminum plate on which an anodized film is formed is immersed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and even more preferably 20 seconds or shorter.

Examples of the hydrophilization treatment used in the present invention include US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There is an alkali metal silicate method as described in the book. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinyl phosphonic acid as described in each specification of No. 272.
The support of the present invention preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance can be obtained.

(3-1-2) Step of Injecting Inkjet Recording Ink onto the Hydrophilic Support When the inkjet recording ink of the present invention is ejected onto the surface of the hydrophilic support, the inkjet recording ink is 40 to The ink composition is preferably ejected after being heated to 80 ° C., preferably 25 to 30 ° C., to lower the viscosity of the ink composition to 7 to 30 mPa · s, preferably 7 to 20 mPa · s. In particular, when an ink composition having an ink viscosity of 35 to 500 MP · s at 25 ° C. is used, a great effect can be obtained. By using this method, high injection stability can be realized. A radiation curable ink jet recording ink such as the ink of the present invention generally has a higher viscosity than a water-based ink generally used in ink jet recording inks, and therefore has a large viscosity fluctuation due to temperature fluctuations during printing. The ink viscosity fluctuation has a great influence on the change in the droplet size and the change in the ejection speed of the droplets, thereby causing deterioration of the image quality. Therefore, it is necessary to keep the temperature of ink at the time of printing as constant as possible. Therefore, it is appropriate that the control range of the temperature of the present invention is the set temperature ± 5 ° C., preferably the set temperature ± 2 ° C., more preferably the set temperature ± 1 ° C.

(3-1-3) Step of curing the ink by irradiating the hydrophilic support on which the ink has been ejected The ink ejected on the surface of the hydrophilic support is cured by irradiating the radiation. To do. This is because the sensitizing dye in the polymerization initiation system contained in the ink for ink jet recording of the present invention absorbs radiation to be in an excited state, and the polymerization initiator is decomposed by contact with the polymerization initiator in the polymerization initiation system. This is because the polymerizable compound is cured by radical polymerization.
Here, α-rays, γ-rays, electron beams, X-rays, ultraviolet rays, visible light, infrared light, or the like can be used as the radiation used. The peak wavelength of the radiation is, for example, 200 to 600 nm, preferably 300 to 450 nm, more preferably 350 to 450 nm, depending on the absorption characteristics of the sensitizing dye. In addition, the polymerization initiation system of the present invention has sufficient sensitivity even with low output radiation. Thus, the output of radiation, for example, 2000 mJ / cm ² or less, preferably, 10 to 2000 mJ / cm ^2, more preferably, 20~1000mJ / cm ^2, more preferably, irradiation energy of 50 to 800 mJ / cm ² It is appropriate to be. Moreover, it is appropriate that the radiation is irradiated at an exposure surface illuminance of, for example, 10 to 2000 mW / cm ² , preferably 20 to 1000 mW / cm ² .

The ink for ink jet recording of the present invention is appropriately irradiated with such radiation for, for example, 0.01 to 120 seconds, preferably 0.1 to 90 seconds.
Radiation irradiation conditions and a basic irradiation method are disclosed in JP-A-60-132767. Specifically, the light source is provided on both sides of the head unit including the ink ejection device, and the head unit and the light source are scanned by a so-called shuttle method. Irradiation of radiation takes a certain time (for example, 0.01 to 0.5 seconds, preferably 0.01 to 0.3 seconds, more preferably 0.01 to 0.15 seconds) after ink landing. Will be done. In this way, by controlling the time from ink landing to irradiation to an extremely short time, it is possible to prevent the ink that has landed on the recording medium from spreading before curing. Further, since the ink can be exposed to a porous recording medium before the ink penetrates to a deep part where the light source does not reach, residual unreacted monomer can be suppressed, and as a result, odor can be reduced. .
Further, the curing may be completed by another light source that is not driven. In WO99 / 54415, as an irradiation method, a method using an optical fiber or a method in which a collimated light source is applied to a mirror surface provided on the side surface of the head unit to irradiate the recording unit with UV light is disclosed.

By adopting the ink jet recording method as described above, the dot diameter of the landed ink can be kept constant even on various recording media having different surface wettability, and the image quality is improved. In addition, in order to obtain a color image, it is preferable to superimpose in order from the color with the lowest brightness. By superimposing the inks in the order of low lightness, the irradiation line can easily reach the lower ink, and good curing sensitivity, reduction of residual monomers, reduction of odor, and improvement of adhesion can be expected. Irradiation can be performed by injecting all colors and exposing them together, but exposure for each color is preferable from the viewpoint of curing acceleration.
In this way, the ink for inkjet recording of the present invention is cured by irradiation with radiation, and forms a hydrophobic image on the surface of the hydrophilic support.

(3-2) Inkjet recording apparatus The inkjet recording apparatus used in the present invention is not particularly limited, and a commercially available inkjet recording apparatus can be used. That is, in the present invention, recording can be performed on a recording medium using a commercially available inkjet recording apparatus.
The ink jet recording apparatus of the present invention includes, for example, an ink supply system, a temperature sensor, and a radiation source.
The ink supply system includes, for example, an original tank containing the ink jet recording ink of the present invention, a supply pipe, an ink supply tank immediately before the ink jet head, a filter, and a piezo ink jet head. The piezo-type inkjet head has a multi-size dot of 1 to 100 pl, preferably 8 to 30 pl, for example, 320 × 320 to 4000 × 4000 dpi, preferably 400 × 400 to 1600 × 1600 dpi, and more preferably 720 × 720 dpi. It can drive so that it can inject with the resolution of. In the present invention, dpi represents the number of dots per 2.54 cm.

As described above, since it is desirable that the radiation curable ink has a constant temperature for the ejected ink, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion. The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors at each piping site and perform heating control according to the ink flow rate and the environmental temperature. The temperature sensor can be provided in the vicinity of the ink supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

As a radiation source, a mercury lamp, a gas / solid laser or the like is mainly used, and a mercury lamp and a metal halide lamp are widely known as ultraviolet light curable ink jets. However, from the viewpoint of environmental protection, mercury-free is strongly desired, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long life, have high efficiency, and are low in cost, and are expected as light sources for photocurable ink jets.
In addition, a light emitting diode (LED) and a laser diode (LD) can be used as a radiation source. In particular, when an ultraviolet light source is required, an ultraviolet LED and an ultraviolet LD can be used. For example, Nichia Corporation has launched a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. When even shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit radiation centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. Particularly preferred radiation sources in the present invention are UV-LEDs, and particularly preferred are UV-LEDs having a peak wavelength in the range of 350 to 420 nm.

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

<Synthesis of Graft Polymer (A-1) Having Hydrophobic Component in Side Chain>
[Synthesis of hydrophobic macromers]
After dissolving 42 g of methyl methacrylate and 3.8 g of 3-mercaptopropionic acid in 84 g of methyl ethyl ketone, the temperature was raised to 60 ° C. in a nitrogen atmosphere, and 300 mg of a thermal polymerizable initiator 2,2-azobisisobutyronitrile (AIBN) was added. For 6 hours. After the reaction, it was poured into water, the polymer was precipitated, filtered, and sufficiently washed with water to obtain 43.5 g of a terminal carboxylic acid prepolymer (carboxylic acid value 0.75 meq / g, weight average molecular weight 1. 8 × 10 ³ ).
20 g of the obtained prepolymer was dissolved in 62 g of N, N-dimethylacetamide, and 6.71 g of glycidyl methacrylate, 504 mg of N, N-dimethyldodecylamine (catalyst) and 62.4 mg of hydroquinone (polymerization inhibitor) were added at 130 ° C. The reaction was continued for 6 hours. After the reaction, it was poured into water to precipitate the polymer, and washed well to obtain 23.4 g of terminal methacrylate methyl methacrylate macromonomer. (Weight average molecular weight: 1.8 × 10 ³ ). ^{From 1} H-NMR (CDCl ₃ ) 6.12, 5.70 ppm methacryloyl group olefin peak and a decrease in carboxylic acid value (0.043 meq / g), it was confirmed that a polymerizable group could be introduced at the terminal.

[Synthesis of Graft Polymer (A-1)]
15 g of 1-methoxy-2-propanol was put into a flask, heated to 60 ° C. in a nitrogen atmosphere, 10 g of the macromonomer, 5 g of methacrylamide, 150 mg of 2,2′-azobisisobutyronitrile, a thermal polymerizable initiator. Was dissolved in 1 g of 1-methoxy-2-propanol over 2 hours. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain 14.5 g of a graft polymer (A-1) having a hydrophobic constituent component in the side chain (weight average molecular weight 1.30 × 10 ⁵ ).

<Synthesis of Graft Polymer (A-2 to 5) Having Hydrophobic Component in Side Chain>
The hydrophilic monomer (methacrylamide) used for the synthesis of the graft polymer (A-1) was changed as shown in Table 1 and the composition ratio of the monomers was changed, and the same as the synthesis of the graft polymer (A-1). Hydrophobic macromers and hydrophilic monomers were copolymerized by the method to obtain graft polymers (A-2) to (A-5). The weight average molecular weight is shown in Table 1.

<Synthesis of Graft Polymer (B-1) Having Hydrophobic Component in Side Chain>
[Synthesis of hydrophobic macromers]
After dissolving 44 g of styrene and 3.8 g of 3-mercaptopropionic acid in 88 g of methyl ethyl ketone, the temperature was raised to 60 ° C. in a nitrogen atmosphere, and 300 mg of a thermal polymerizable initiator 2,2′-azobisisobutyronitrile (AIBN) was added. For 6 hours. After the reaction, it was poured into water, the polymer was precipitated, filtered, and sufficiently washed with water to obtain 43.5 g of a terminal carboxylic acid prepolymer (carboxylic acid value 0.76 meq / g, weight average molecular weight 1. 9 × 10 ³ ).
20 g of the obtained prepolymer was dissolved in 62 g of N, N-dimethylacetamide, and 6.71 g of glycidyl methacrylate, 504 mg of N, N-dimethyldodecylamine (catalyst) and 62.4 mg of hydroquinone (polymerization inhibitor) were added at 130 ° C. The reaction was continued for 6 hours. After the reaction, it was poured into water to precipitate the polymer and washed well to obtain 23.4 g of terminal methacrylate styrene macromonomer. (Weight average molecular weight: 1.8 × 10 ³ ). ^{From 1} H-NMR (CDCl ₃ ) 6.12, 5.70 ppm methacryloyl group olefin peak and a decrease in carboxylic acid value (0.041 meq / g), it was confirmed that a polymerizable group could be introduced at the terminal.

(Synthesis of graft polymer)
15 g of 1-methoxy-2-propanol was placed in a flask, heated to 60 ° C. in a nitrogen atmosphere, 10 g of the above-mentioned terminal methacrylate styrene macromonomer, 5 g of methacrylamide, thermal polymerizable initiator 2,2′-azobisisobutyrate. A solution of 150 mg of nitrile dissolved in 15 g of 1-methoxy-2-propanol was added dropwise over 2 hours. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain 14.5 g of a graft polymer (B-1) having a hydrophobic segment as a graft chain (weight average molecular weight 1.2 × 10 ⁵ ).

<Synthesis of Graft Polymer (B-2 to 5) Having Hydrophobic Component in Side Chain>
The hydrophilic monomer shown in Table 2 was used in place of the hydrophilic monomer (methacrylamide) used in the synthesis of the graft polymer (B-1), and the graft polymer (A-1) was used except that the composition ratio of the monomers was changed. Graft polymers (B-2) to (B-5) were obtained in the same manner as in the synthesis. The weight average molecular weight is shown in Table 2.

<Synthesis of Graft Polymer (A′-1) Having Hydrophobic Component in Main Chain>
(Synthesis of hydrophilic macromer)
30 g of acrylamide and 3.8 g of 3-mercaptopropionic acid are dissolved in 70 g of ethanol, the temperature is raised to 60 ° C. in a nitrogen atmosphere, and 300 mg of a thermal polymerizable initiator 2,2′-azobisisobutyronitrile (AIBN) is added. For 6 hours. After the reaction, the white precipitate was filtered and sufficiently washed to obtain 30.8 g of a terminal carboxylic acid prepolymer (carboxylic acid value 0.78 meq / g, weight average molecular weight 1.3 × 10 ³ ).
20 g of the obtained prepolymer was dissolved in 62 g of N, N-dimethylacetamide, and 6.71 g of glycidyl methacrylate, 504 mg of N, N-dimethyldodecylamine (catalyst) and 62.4 mg of hydroquinone (polymerization inhibitor) were added at 130 ° C. The reaction was continued for 6 hours. After the reaction, it was put into acetone, the polymer was precipitated, and washed well to obtain 23.4 g of terminal methacrylate acrylamide macromonomer. (Weight average molecular weight: 1.4 × 10 ³ ). ¹ H-NMR (D ₂ O) 6.12, 5.70 ppm The presence of a methacryloyl group olefin peak and a decrease in the carboxylic acid value (0.023 meq / g) confirmed that a polymerizable group could be introduced at the terminal. did. The glass transition temperature of the hydrophilic macromer was measured by a differential scanning calorimeter (DSC) manufactured by Seiko Instruments Inc. and found to be 160 ° C.

(Synthesis of graft polymer)
Take 15 g of N, N-dimethylacetamide amide in a flask, raise the temperature to 60 ° C. under a nitrogen atmosphere, 10 g of the macromonomer, 5 g of methyl methacrylate, thermal polymerizable initiator 2,2′-azobisisobutyronitrile. A solution prepared by dissolving 150 mg in 15 g of N, N-dimethylacetamide amide was added dropwise over 2 hours. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain 14.5 g of a graft polymer (A′-1) having a hydrophobic constituent component in the main chain. The weight average molecular weight is shown in Table 3.

<Synthesis of Graft Polymer (A′-2 to 5) Having Hydrophobic Component in Main Chain>
The hydrophobic monomer (methyl methacrylate) in the above synthesis example was changed as shown in Table 3, and the graft polymer (A'-1) was synthesized in the same manner as the synthesis of the graft polymer (A'-1) except that the composition ratio of the monomers was changed. -2) to (A'-5) were obtained. The weight average molecular weight is shown in Table 3.

<Synthesis of Graft Polymer (B′-1) Having Hydrophobic Component in Main Chain>
(Synthesis of hydrophilic macromer)
After dissolving 40 g of N, N-dimethylacrylamide and 3.8 g of 3-mercaptopropionic acid in 95 g of ethanol, the temperature was raised to 60 ° C. in a nitrogen atmosphere, and a thermal polymerizable initiator 2,2′-azobisisobutyronitrile ( AIBN) 300 mg was added and reacted for 6 hours. After the reaction, the white precipitate was filtered and sufficiently washed to obtain 38.5 g of a terminal carboxylic acid prepolymer (carboxylic acid value 0.75 meq / g, weight average molecular weight 1.25 × 10 ³ ).
20 g of the obtained prepolymer was dissolved in 62 g of N, N-dimethylacetamide, and 6.71 g of glycidyl methacrylate, 504 mg of N, N-dimethyldodecylamine (catalyst) and 62.4 mg of hydroquinone (polymerization inhibitor) were added at 130 ° C. The reaction was continued for 6 hours. After the reaction, it was put into acetone, the polymer was precipitated, and washed well to obtain 23.4 g of terminal methacrylate acrylamide macromonomer. (Weight average molecular weight: 1.33 × 10 ³ ). ¹ H-NMR (D ₂ O) 6.12, 5.70 ppm The presence of a methacryloyl group olefin peak and a decrease in the carboxylic acid value (0.019 meq / g) confirmed that a polymerizable group could be introduced at the terminal. did. The glass transition temperature of the hydrophilic macromer was measured with a differential scanning calorimeter (DSC) manufactured by Seiko Instruments Inc. and found to be 90 ° C.

(Synthesis of graft polymer)
Take 15 g of N, N-dimethylacetamide amide in a flask, raise the temperature to 60 ° C. under a nitrogen atmosphere, 10 g of the macromonomer, 5 g of methyl methacrylate, thermal polymerizable initiator 2,2′-azobisisobutyronitrile. A solution prepared by dissolving 150 mg in 15 g of N, N-dimethylacetamide amide was added dropwise over 2 hours. After completion of dropping, heating was continued for 6 hours. The product was precipitated and washed well to obtain 14.5 g of a graft polymer (B′-1) having a hydrophobic constituent component in the main chain (weight average molecular weight 1.0 × 10 ⁵ ).

<Synthesis of Graft Polymer (B′-2 to 5) Having Hydrophobic Component in Main Chain> The hydrophobic monomer (methyl methacrylate) in the above synthesis example is changed as shown in Table 4, and the composition ratio of the monomers is changed. Graft polymers (B′-2) to (B′-5) were obtained in the same manner as the synthesis of the graft polymer (B′-1) except that the polymer was changed. The weight average molecular weight is shown in Table 4.

Example 1
<< Preparation of pigment dispersion >>
According to the method described below, yellow, magenta, cyan and black pigment dispersions 1 were prepared. The dispersion conditions are adjusted appropriately using a known dispersion device so that the average particle diameter of each pigment particle is in the range of 0.2 to 0.3 μm, and then filtered under heating. Prepared by filtration.

(Yellow pigment dispersion 1)
C. I. Pigment Yellow 12 10 parts by weight Polymer Dispersant (Solsperse series manufactured by Zeneca) 5 parts by weight Stearyl Acrylate 85 parts by weight (Magenta Pigment Dispersion 1)
C. I. Pigment Red 57: 1 15 parts by mass Polymer dispersant (Solsperse series manufactured by Zeneca) 5 parts by mass Stearyl acrylate 80 parts by mass

(Cyan pigment dispersion 1)
C. I. Pigment Blue 15: 3 20 parts by mass Polymer dispersing agent (Solsperse series manufactured by Zeneca) 5 parts by mass Stearyl acrylate 75 parts by mass (Black pigment dispersion 1)
C. I. Pigment Black 7 20 parts by mass Polymer dispersing agent (Solsperse series manufactured by Zeneca) 5 parts by mass Stearyl acrylate 75 parts by mass

<Preparation of ink>
Each color ink was prepared using each of the dispersions 1 prepared above according to the method described below.

(Yellow ink 1)
Yellow pigment dispersion 1 20 parts by mass Stearyl acrylate 30 parts by mass Specific resin A 30 parts by mass The following bifunctional aromatic urethane acrylate (molecular weight 1500) 10 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization Initiator (Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

(Magenta ink 1)
Magenta pigment dispersion 1 20 parts by mass Stearyl acrylate 30 parts by mass Specific resin B 30 parts by mass The following bifunctional aromatic urethane acrylate (molecular weight 1500) 10 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization Initiator (Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

(Cyan ink 1)
Cyan pigment dispersion 1 15 parts by mass Stearyl acrylate 30 parts by mass Specific resin C 30 parts by mass The following bifunctional aromatic urethane acrylate (molecular weight 1500) 10 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization Initiator (Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

(Black ink 1)
Black pigment dispersion 1 15 parts by mass Stearyl acrylate 30 parts by mass Specific resin D 30 parts by mass The following bifunctional aromatic urethane acrylate (molecular weight 1500) 10 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization Initiator (Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass Each color ink 1 prepared as described above was filtered with a filter having an absolute filtration accuracy of 2 μm to obtain ink 1 of each color.

<Inkjet image recording>
Next, recording on a recording medium was performed using a commercially available inkjet recording apparatus having a piezoelectric inkjet nozzle. The ink supply system was composed of an original tank, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head, and heat insulation and heating were performed from the ink supply tank to the inkjet head portion. Temperature sensors were provided near the ink supply tank and the nozzles of the ink jet head, respectively, and temperature control was performed so that the nozzle portions were always 70 ° C. ± 2 ° C. The piezo-type inkjet head was driven so that 8 to 30 pl multi-size dots could be ejected at a resolution of 720 × 720 dpi. After landing, UV-A light is condensed to an exposure surface illuminance of 100 mW / cm ² , and the exposure system, main scanning speed and ejection frequency are adjusted so that irradiation starts 0.1 seconds after ink landing on the recording medium. . Further, the exposure time was variable, and exposure energy was irradiated. In the present invention, dpi represents the number of dots per 2.54 cm.

Each color ink prepared above was ejected in the order of black → cyan → magenta → yellow at an ambient temperature of 25 ° C. and irradiated with ultraviolet light for each color. In order to eliminate tackiness by palpation, the exposure was performed with a total exposure energy per color of 300 mJ / cm ² as the energy for complete curing. As recording media, each color image was recorded on a grained aluminum support, a transparent biaxially stretched polypropylene film having a printability, a soft vinyl chloride sheet, cast coated paper, and commercially available recycled paper. However, in both cases, a high-resolution image without dot bleeding was obtained. Furthermore, even on high-quality paper, the ink was sufficiently cured without causing the ink to turn around, and there was almost no odor due to unreacted monomers. Further, the ink recorded on the film had sufficient flexibility, and the ink was not cracked even when it was bent, and there was no problem in the adhesion test by peeling the cello tape (registered trademark).

Examples 2-5
<Preparation of ink>
Magenta inks 2-5 were prepared according to the method described below.

(Magenta ink 2)
Magenta pigment dispersion 1 20 parts by mass Isobornyl acrylate 20 parts by mass Specific resin E 20 parts by mass The following bifunctional aromatic urethane acrylate (molecular weight 1500) 10 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization initiator (Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

(Magenta ink 3)
Magenta pigment dispersion 1 20 parts by mass Isobornyl acrylate 30 parts by mass Specific resin F 20 parts by mass The following lactone-modified acrylate (molecular weight 458) 20 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization start Agent (Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

(Magenta ink 4)
Magenta pigment dispersion 2 20 parts by mass Isobornyl acrylate 40 parts by mass Specific resin G 30 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization initiator (manufactured by Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

<Preparation of magenta pigment dispersion 2>
A magenta pigment dispersion 2 was prepared in the same manner as in the preparation of the magenta pigment dispersion 1 described in Example 1, except that isobornyl acrylate was used instead of stearyl acrylate.

(Magenta ink 5)
Magenta pigment dispersion 2 20 parts by mass Isobornyl acrylate 30 parts by mass Specific resin H 30 parts by mass Tetramethylolmethane triacrylate 15 parts by mass Polymerization initiator (manufactured by Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

Comparative Examples 1-2
<Preparation of ink>
Magenta inks 6-7 were prepared according to the method described below.
(Magenta ink 6: Comparative example 1)
Magenta pigment dispersion 1 20 parts by mass Stearyl acrylate 60 parts by mass The following bifunctional aromatic urethane acrylate (molecular weight 1500) 10 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization initiator (Ciba Specialty)・ Made by Chemicals,
IRGACURE 184) 5 parts by mass

(Magenta ink 7: Comparative example 2)
Magenta Pigment Dispersion 2 20 parts by mass Isobornyl acrylate 70 parts by mass The following hexafunctional aliphatic urethane acrylate (molecular weight 1000) 5 parts by mass Polymerization initiator (manufactured by Ciba Specialty Chemicals,
IRGACURE 184) 5 parts by mass

  In the ink compositions prepared in the above examples and comparative examples, the ink viscosity at the ejection temperature is 7 to 20 mPa.s. It was within the range of s.

<Inkjet image recording>
Using the magenta inks 2 to 7 prepared as described above and the magenta ink 1 prepared in Example 1, magenta image printing was performed in the same manner as in the method described in Example 1.

<Evaluation of inkjet image>
Next, for each formed image, in accordance with the method described below, sensitivity required for curing, permeability in commercially available recycled paper, ink bleeding on a grained aluminum support, adhesion, printing durability, storage The stability was evaluated.

(Measurement of curing sensitivity)
The amount of exposure energy (mJ / cm ² ) at which the sticky feeling disappears on the image surface after ultraviolet irradiation was defined as the curing sensitivity. The smaller the value, the higher the sensitivity.

(Permeability evaluation for commercial recycled paper)
For images printed on commercially available recycled paper, permeability was evaluated according to the following criteria.
○: Almost no penetration and no residual monomer odor △: Slight penetration and slight residual monomer odor X: Clearly the ink penetrates the back side and the residual monomer odor is strong

(Evaluation of ink bleeding on grained aluminum support)
For images printed on a grained aluminum support, ink bleeding was evaluated according to the following criteria.
○: No blur between adjacent dots Δ: Slightly blur dots ×: Dot blurs and the image is clearly blurred

(Evaluation of adhesion in grained aluminum support)
With respect to the print image created above, a sample that does not scratch the print surface at all, and in accordance with JISK 5400, 11 cuts are made on the print surface at 1 mm intervals vertically and horizontally, and a 1 mm square grid 100 is formed. Individual samples were prepared, and a cellophane tape was applied to each printing surface. The sample was peeled off quickly at an angle of 90 degrees, and the state of the printed image remaining without peeling or the grid pattern was evaluated according to the following criteria.
○: No peeling of the printed image is observed even in the cross cut test. Δ: Some peeling of the ink is recognized in the cross cut test, but almost no peeling is observed unless the ink surface is scratched. Easy to peel off with cello tape (registered trademark)

(Evaluation of printing durability)
The image printed on the grained aluminum support prepared above was used as a printing plate, and after printing with a Heidel KOR-D machine, the number of finished sheets was relatively compared as an index of printing durability (Example 1 was set to 100). ). A larger numerical value is preferable because it has a higher printing durability.

(Evaluation of smoothness)
The image printed on the grained aluminum support was visually observed for ink film thickness and unevenness, and evaluated according to the following criteria.

◎: Image thickness is thin and good image quality ○: Image has thickness but no unevenness, high-definition printed image △: Image has thickness and some unevenness is observed, but practical Table A shows the evaluation results obtained as described above because the image has a thickness and the image unevenness is conspicuous and the quality is a practical problem.
These evaluation results are shown in Table A.

表Ａより、本発明における特定のグラフトポリマーを用いたインク組成物は、放射線の照射に対して高感度であり、紙への画像形成性においても高画質の画像を形成することができ、また印刷版の作製に用いた場合であっても、高耐刷、かつ高画質の画像の形成が可能であることが分かる（実施例１〜５）。一方、本発明の特定のグラフトポリマーを使用しない場合には、感度が低く、浸透性、インク滲みなど紙への画像形成性が不良であった。また、印刷版の作製に用いた場合には、密着性、平滑性及び耐刷性のいずれもが不満足な結果であった。

From Table A, the ink composition using the specific graft polymer in the present invention is highly sensitive to radiation irradiation, and can form a high-quality image even in the image-forming property on paper. It can be seen that even when used for producing a printing plate, it is possible to form images with high printing durability and high image quality (Examples 1 to 5). On the other hand, when the specific graft polymer of the present invention was not used, the sensitivity was low, and image forming properties on paper such as penetrability and ink bleeding were poor. Moreover, when it was used for preparation of a printing plate, all of adhesiveness, smoothness, and printing durability were unsatisfactory results.

Claims (4)

An ink for ink-jet recording comprising at least one polymerizable compound and a coloring material, which can be cured by irradiation with radiation, and further contains at least one graft (co) polymer. . The graft (co) polymer (i) is a graft (co) polymer containing a hydrophobic constituent in the side chain, and is an acrylic ester, methacrylic ester, vinyl ester, styrene, acrylonitrile A monomer comprising at least one hydrophobic macromer containing at least one hydrophobic monomer selected from the group consisting of methacrylonitrile, maleic anhydride, and maleic imide as a constituent unit, and at least one hydrophilic monomer The above graft (co) polymer as a unit, or (ii) a graft (co) polymer containing a hydrophobic constituent in the main chain, which is an acrylic ester, methacrylic ester, vinyl ester, styrene Selected from the group consisting of acrylonitrile, methacrylonitrile, maleic anhydride, and maleic imide 2. The ink jet recording according to claim 1, wherein the graft (co) polymer contains at least one kind of an aqueous monomer and at least one kind of hydrophilic macromer containing at least one kind of hydrophilic monomer as a constituent unit as a monomer unit. ink. A lithographic printing plate having a hydrophobic image containing the inkjet recording ink according to claim 1 on a hydrophilic support. The inkjet recording ink according to claim 1 or 2 is ejected onto a hydrophilic support and then irradiated with radiation to be cured to form a hydrophobic image, whereby a lithographic printing plate requiring no development treatment is obtained. A method for preparing a lithographic printing plate.