JP4907187B2 - Ink composition, inkjet recording method, lithographic printing plate production method, and lithographic printing plate - Google Patents

Description

  The present invention relates to an ink composition suitably used for inkjet recording, an inkjet recording method, a lithographic printing plate obtained using the ink, and a method for producing a lithographic printing plate. Specifically, an ink composition suitable for ink jet recording, which is cured with high sensitivity to irradiation with actinic radiation, and the cured product has sufficient flexibility after ink curing, an ink jet recording method, and the ink are used. The lithographic printing plate obtained in this way and a method for producing the lithographic printing plate.

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 system is inexpensive, there are problems such as high running costs and waste materials due to the use of ink ribbons.
On the other hand, the ink jet method is an inexpensive apparatus and ejects ink only to a required image portion to form an image directly on a recording medium. Therefore, the ink can be used efficiently and the running cost is low. Furthermore, there is little noise and it is excellent as an image recording method.

  As an ink composition (radiation curable ink composition) curable by irradiation with active radiation such as ultraviolet rays, for example, an ink composition for inkjet recording,

  There has been proposed an ink composition using a combination of a plurality of monomers having different degrees of functionality (for example, see Patent Document 1). However, in order to maintain the curing speed in such an ink composition, many polyfunctional monomers must be used, and in this case, there is a problem in the flexibility of the image after ink curing.

Conventionally, in the production of a lithographic printing plate, a so-called PS plate having a configuration in which an oleophilic photosensitive resin layer is provided on a hydrophilic support is used, and the photosensitive resin layer is exposed imagewise. Thus, an image is formed by improving or decreasing the solubility of the exposed portion in an alkaline developer, and the non-image portion is dissolved and removed. However, in recent years, digitization technology for electronically processing, storing, and outputting image information using a computer has become widespread, and a new image output method corresponding to the technology has been demanded. In particular, a method capable of producing a printing plate without undergoing treatment with a developing solution has been studied, and a method of directly producing a lithographic printing plate using an ink composition for inkjet recording has been studied. This is preferably a printing plate having a desired image (preferably a hydrophobic image) by ejecting ink onto the surface of a hydrophilic support in an image-like manner by an inkjet method or the like and irradiating it with actinic radiation to cure it. Is what you get. In order to form an image part of a lithographic printing plate, ink droplets ejected on a support are cured quickly without causing bleeding, and the strength of the cured image part and adhesion to the support are excellent. In addition, it is desired that the image portion follows the flexure of the support when the lithographic printing plate is mounted on a printing machine so that damage such as cracks does not occur. Ink compositions suitable for such applications The current situation is that something is desired.
Japanese Patent Laid-Open No. 5-214280

An object of the present invention is an ink composition for ink jet recording, which can be cured with high sensitivity to irradiation with actinic radiation, can form a high-quality image, and the image obtained by curing the ink has sufficient flexibility. And an ink jet recording method using the ink composition.
Another object of the present invention is to provide a lithographic printing plate obtained using an ink composition that can be cured with high sensitivity by irradiation with actinic radiation such as ultraviolet rays, and a method for producing the lithographic printing plate. is there.

As a result of intensive studies, the present inventors have improved the flexibility after ink curing while maintaining high sensitivity by using a specific polymer compound in the ink composition for ink jet recording. The inventors have found that an ink composition for ink jet recording having improved adhesion to the ink can be obtained, and the present invention has been completed.
That is, the ink composition for inkjet recording of the present invention comprises (A) a polymerization initiator, (B) a polymerizable compound, (C) a colorant, and (D) a repeating unit represented by the following general formula (I). containing a polymer compound having, water not containing organic and the range of 0.5 to 5% by weight relative to the total weight of the ink composition when containing or organic solvents containing no organic solvent It is characterized by being.

  In general formula (I), n represents an integer of 1 to 5.

The ink composition of the present invention, the radiation cured with high sensitivity, and the flexibility of the film formed on the surface of the ink is also preferable to Louis inkjet recording ink composition improved.

The inkjet recording method of the present invention includes (a) a step of ejecting the ink composition for inkjet recording of the present invention onto a recording medium, and (b) irradiating the ejected ink composition with actinic radiation. And a step of curing the ink composition.
The lithographic printing plate production method of the present invention comprises: (a ′) a step of ejecting the ink composition for inkjet recording of the present invention onto a hydrophilic support; and (b ′) active on the ejected ink composition. Forming a hydrophobic image formed by curing the ink composition on the hydrophilic support by irradiating radiation to cure the ink composition.
The lithographic printing plate of the present invention is produced by the method for producing a lithographic printing plate of the present invention.

As described above, according to the present invention, it can be cured with high sensitivity to irradiation with actinic radiation, can form a high-quality image, and the image obtained by curing the ink has sufficient flexibility. An ink composition for ink jet recording and an ink jet recording method using the ink composition can be provided.
Moreover, the planographic printing plate obtained using the ink composition which can be hardened | cured with high sensitivity by irradiation of active radiations, such as an ultraviolet-ray, and the manufacturing method of a planographic printing plate can be provided.

<Ink composition>
The ink composition of the present invention comprises (A) a polymerization initiator, (B) a polymerizable compound, (C) a colorant, and (D) a polymer compound having a repeating unit represented by the following general formula (I). containing, water not containing organic and, characterized in that when or contain organic solvent containing no organic solvent is in the range of 0.5 to 5% by weight relative to the total weight of the ink composition An ink composition for ink jet recording.
Hereinafter, components essential to the ink composition of the present invention will be sequentially described.

[(D) Polymer compound having a repeating unit represented by formula (I)]
The ink composition of the present invention contains (D) a polymer compound having a repeating unit represented by the following general formula (I) (hereinafter, referred to as “specific polymer” as appropriate).

  In general formula (I), n represents an integer of 1 to 5, and n is 2 to 2 from the viewpoint of flexibility after the ink composition is cured, adhesion to a recording medium, and availability of raw materials. It is preferably an integer of 4 and more preferably n is an integer of 2 or 4.

The specific polymer may be a copolymer containing other monomer components other than the repeating unit represented by the general formula (I).
One type of other monomer component may be contained in the specific polymer, or two or more types may be contained.

  The copolymerization ratio of other monomer components in the specific polymer is preferably 75 mol% or less, and more preferably 50 mol% or less in the specific polymer.

  Examples of other monomer components contained in the specific polymer include those derived from the monomers listed in the following (1) to (17).

(1) Monomer having a phenolic hydroxyl group (—Ar—OH) Examples of the monomer having a phenolic hydroxyl group include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, and hydroxystyrene having a phenolic group.
(2) Monomer having sulfonamide group (—SO ₂ NH—R) As the monomer having a sulfonamide group, a compound having at least one sulfonamide group having the above structure and one polymerizable unsaturated group in the molecule. Is mentioned. Among these, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group and a sulfonamide group in the molecule is preferable.
(3) Monomer having an active imide group (—SO ₂ NHCOR, —SO ₂ NHSO ₂ R, —CONHSO ₂ R) The monomer having an active imide group is polymerizable with the active imide group represented by the above structural formula. Examples thereof include compounds each having one or more unsaturated groups in the molecule. Among these, compounds having at least one active imide group represented by the following structural formula and one polymerizable unsaturated group in the molecule are preferable. Specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.
(4) Monomer having a carboxylic acid group (—COOH) Examples of the monomer having a carboxylic acid group include compounds having at least one carboxylic acid group and one or more polymerizable unsaturated groups in the molecule. .
(5) Monomer having a sulfonic acid group (—SO ₃ H) Examples of the monomer having a sulfonic acid group include compounds having at least one sulfonic acid group and one polymerizable unsaturated group in the molecule. Can do.
(6) Monomer having phosphate group (—OPO ₃ H ₂ ) Examples of the monomer having a phosphate group include compounds each having at least one phosphate group and one polymerizable unsaturated group in the molecule. be able to.
In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrocarbon group which may have a substituent.

(7) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(8) Methyl acrylate, ethyl acrylate, propyl acrylate, amyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoalkylate Acrylates and the like.
(9) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate, polyethylene glycol monomethacrylate, polypropylene Methacrylates such as glycol monomethacrylate.
(10) Acrylamide, methacrylamide, N-methylolacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.
(11) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and phenyl vinyl ether.
(12) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(13) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene.
(14) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(15) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(16) N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
(17) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.

  Among the above, the monomers (7), (8), (9), (10), (11), (12) and (13) are soluble and copolymerizable with the specific polymer in the ink composition. In view of the above, monomers (8), (9), (11), (12) and (13) are more preferable.

  Specific examples (D-1) to (D-20) of the specific polymer (D) according to the present invention are listed below, but the present invention is not limited to these. In the specific examples, the numerical value at the lower right of the parenthesis represents the molar ratio of each repeating unit constituting the polymer, and those without a numerical value represent a 100% homopolymer.

  (D) The molecular weight of the specific polymer is preferably 1,000 to 1,000,000, more preferably 2,000 to 200,000, and particularly preferably 5,000 to 100,000 in terms of weight average molecular weight.

(D) The specific polymer is polymerized by a known polymerization method. Preferable methods include radical polymerization, anionic polymerization, cationic polymerization, coordination polymerization and the like, and radical polymerization is preferable from the viewpoint of ease of production.
The reaction solvent used as necessary when performing radical polymerization can be used without limitation as long as it is a solvent that can dissolve the above-described polymerization components. From the viewpoint of little influence on the radical polymerization reaction and from the viewpoint of solubility of each monomer, ketone solvents such as acetone and methyl ethyl ketone, alcohol solvents such as methanol, ethanol, isopropyl alcohol and 1-methoxy-2-propanol, N and N Preferred examples of the solvent include amide solvents such as dimethylacetamide and N, N-dimethylformamide, and dimethyl sulfoxide.
Moreover, as a polymerization initiator used as needed, various thermal polymerization initiators and photopolymerization initiators can be used. From the viewpoint of handleability and availability, azo-based thermal polymerization initiators are preferable, and specifically, azonitrile such as V-70, V-60, V-65 (all manufactured by Wako Pure Chemical Industries, Ltd.). Compounds: Asiamidine compounds such as VA-545 and VA-041 (both manufactured by Wako Pure Chemical Industries, Ltd.), etc .: Azoamide compounds such as VA-080 and VA-082 (both manufactured by Wako Pure Chemical Industries, Ltd.) : Other azo compounds such as V-601, V-501, and VF-077 (all manufactured by Wako Pure Chemical Industries, Ltd.). Among these, V-65 and V-601 are particularly preferable polymerization initiators.
Furthermore, in the polymerization, the composition and molecular weight of the terminal portion of the polymer may be controlled by using a known chain transfer agent typified by a mercapto compound or the like. Each copolymer component constituting the specific polymer may be introduced into the specific polymer in a block or random state.

In the ink composition of the present invention, the content of the specific polymer (D) is based on the balance of the curing speed and flexibility after curing, and from the viewpoint of ink jet suitability of the ink composition, with respect to the total mass of the ink composition. The range is preferably 1 to 20% by mass, more preferably 2 to 18% by mass, and still more preferably 2 to 15% by mass.
(D) When the content of the specific polymer exceeds 20%, the compatibility in the composition may be insufficient, the stickiness of the cured film, and the flexibility may be reduced. The speed improvement effect may not be recognized.
In addition, (D) the specific polymer may be used alone or in combination of two or more in the ink composition of the present invention.

[(A) Polymerization initiator]
The ink composition of the present invention contains a polymerization initiator. As the polymerization initiator, a known polymerization initiator can be used. In the present invention, it is preferable to use a radical polymerization initiator.
The polymerization initiator used in the ink composition of the present invention is a compound that absorbs external energy and generates a polymerization initiating species. External energy used for initiating polymerization is roughly divided into heat and radiation, and a thermal polymerization initiator and a photopolymerization initiator are used, respectively. Examples of radiation include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays.
Known compounds can be used as the thermal polymerization initiator and the photopolymerization initiator.

Preferred radical polymerization initiators that can be used in the present invention include (a) aromatic ketones, (b) acylphosphine compounds, (c) aromatic onium salt compounds, (d) organic peroxides, and (e) thio compounds. (F) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen bond And (m) an alkylamine compound.
The radical polymerization initiator in the present invention may be used alone or in combination.

The (A) polymerization initiator in the present invention is preferably 0.01 to 35% by mass, more preferably 0.1 to 30% by mass, and still more preferably based on the total amount of the (B) polymerizable compound described later. It is suitable to contain in the range of 0.5-30 mass%.
Further, (A) the polymerization initiator is a mass ratio of polymerization initiator: sensitizing dye with respect to (E) sensitizing dye that can be used as necessary, which will be described later, and is 200: 1 to 1: 200. Preferably, it is contained in the range of 50: 1 to 1:50, more preferably 20: 1 to 1: 5.

[(B) Polymerizable compound]
The ink composition of the present invention contains (B) a polymerizable compound.
Examples of the polymerizable compound that can be used in the present invention include a radical polymerizable compound and a cationic polymerizable compound.
The (B) polymerizable compound may be appropriately selected and used in relation to the intended properties or the relationship with the (A) polymerization initiator.

  (B) Content of a polymeric compound becomes like this. Preferably it is 6-55 mass% with respect to the mass of the whole ink composition of this invention, More preferably, it is 10-45 mass%.

  The radical polymerizable compound in the present invention is a compound having an ethylenically unsaturated bond capable of radical polymerization, and any compound having at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. However, those having chemical forms such as monomers, oligomers and polymers are included. 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. It is preferable to use two or more kinds 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, maleic acid, and salts thereof, Examples thereof include radically polymerizable compounds such as anhydrides having a saturated group, 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 Methane derivatives such as tantrimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, N-vinyl compounds such as N-vinylpyrrolidone and N-vinylcaprolactam, allyl glycidyl ether , Derivatives of allyl compounds such as diallyl phthalate and triallyl trimellitate, and more specifically, Shinzo Yamashita, “Crosslinker Handbook”, (1981 Taiseisha); EB Curing Handbook (Raw Materials) "(1985, Polymer Publications); Radtech Study Group," Application and Market of UV / EB Curing Technology ", 79 pages (1989, CMC); Eiichiro Takiyama, Markets listed in "Polyester Resin Handbook" (1988, Nikkan Kogyo Shimbun) Radical polymerizable or crosslinkable monomers, oligomers, and polymers known in the market or in the industry can be used.

  Examples of the radical polymerizable compound include those disclosed in JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-134011, and the like. Photo-curable polymerizable compound materials used for the described photopolymerizable compositions are known, and these can also be applied to the ink composition of the present invention.

Furthermore, it is also preferable to use a vinyl ether compound as the radical polymerizable compound. Suitable vinyl ether compounds include, for example, ethylene glycol divinyl ether, ethylene glycol monovinyl ether, diethylene glycol divinyl ether, triethylene glycol monovinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol. Di- or trivinyl ether compounds such as divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, hydroxyethyl monovinyl ether, hydroxynonyl monovinyl ether, trimethylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octade Monovinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether-O-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether, etc. Examples include vinyl ether compounds.
Of these vinyl ether compounds, divinyl ether compounds and trivinyl ether compounds are preferable from the viewpoints of curability, adhesion, and surface hardness, and divinyl ether compounds are particularly preferable. A vinyl ether compound may be used individually by 1 type, and may be used in combination of 2 or more type as appropriate.

  As other polymerizable compounds in the present invention, (meth) acrylic monomers or prepolymers, (meth) acrylic acid esters such as epoxy monomers or prepolymers, urethane monomers or prepolymers (hereinafter appropriately referred to as acrylate compounds) Is preferably used. More preferably, they are the following compounds.

  That is, 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-poly Tylene glycol acrylate, 2-acryloyloxyethylhexahydrophthalic acid, PO adduct diacrylate of bisphenol A, EO adduct diacrylate of bisphenol A, 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, pentaerythritol triacrylate hexamethyl Nji diisocyanate urethane prepolymer, stearyl acrylate, isoamyl acrylate, isomyristyl acrylate, isostearyl acrylate, lactone-modified acrylate.

  These acrylate compounds have less skin irritation and sensitization (ease of rashes) than conventional polymerizable compounds used in UV curable inks, and can relatively lower the viscosity, providing stable ink ejection. The polymerization sensitivity and the adhesion to the recording medium are also good.

  In addition, the monomers listed here have low sensitization even at low molecular weight, have high reactivity, low viscosity, and excellent adhesion to a recording medium.

In order to further improve sensitivity, bleeding, and adhesion to the recording medium, a monoacrylate containing the component (B) and a polyfunctional acrylate monomer or polyfunctional acrylate oligomer having a molecular weight of 400 or more, preferably 500 or more are used. It is preferable to use together.
In particular, in an ink composition used for recording on a flexible recording medium such as a PET film or a PP film, a monoacrylate selected from the above compound group, one type selected from the aforementioned component (B), The combined use with a polyfunctional acrylate monomer or a polyfunctional acrylate oligomer is preferable because the film strength can be increased while the film is made flexible to improve adhesion.
In addition, the embodiment in which at least three polymerizable compounds of monofunctional, bifunctional, and trifunctional or higher polyfunctional monomers are used in combination further improves sensitivity, bleeding, and adhesion to the recording medium while maintaining safety. From the viewpoint that it can be further improved, it is mentioned as a preferred embodiment.

As monoacrylate, stearyl acrylate, isoamyl acrylate, isomistyl acrylate, and isostearyl acrylate have high sensitivity and low shrinkage to prevent curling, as well as prevention of bleeding, odor of printed matter, and cost reduction of irradiation equipment. preferable.
As the oligomer that can be used in combination with the monoacrylate, an epoxy acrylate oligomer and a urethane acrylate oligomer are particularly preferable.
In addition, methacrylate has better skin irritation than acrylate.
Among the above compounds, when alkoxy acrylate is used in an amount of 70% by mass or less and the balance is acrylate, it is preferable because it has good sensitivity, bleeding characteristics, and odor characteristics.

  In this invention, when using the said acrylate compound as (B) polymeric compound, it is preferable that the said acrylate compound is 30 mass% or more with respect to the total mass of a polymeric compound, and it is 40 mass% or more. Is preferable, and it is still more preferable that it is 50 mass% or more. Moreover, all the (B) polymeric compounds can also be made into the said acrylate compound.

  In the present invention, regarding the selection of the polymerization initiator and the polymerizable compound, radical polymerization may be performed according to various purposes (for example, as a means for preventing a decrease in sensitivity due to the light-shielding effect of the colorant used in the ink composition). In addition to the combination of a reactive compound and a radical polymerization initiator, a radical / cation hybrid curable ink composition may be used in combination with a cationic polymerization compound and a cationic polymerization initiator as shown below.

  The cationically polymerizable compound that can be used in the present invention is not particularly limited as long as it is a compound that initiates a polymerization reaction with an acid generated from a photoacid generator and cures, and various known cations known as photocationically polymerizable monomers. Polymerizable monomers can be used. Examples of the cationic polymerizable monomer 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 2001-2001. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like described in each publication such as No. 220526.

  In addition, as the cationic polymerizable compound, for example, a polymerizable compound applied to a cationic polymerization type photocurable resin is known, and recently, a photo cationic polymerization type sensitized in a visible light wavelength region of 400 nm or more. Examples of the polymerizable compound applied to the photo-curable resin are disclosed in JP-A-6-43633 and JP-A-8-324137. These can also be applied to the ink composition of the present invention.

In the present invention, as the cationic polymerization initiator (photoacid generator) used in combination with the above cationic polymerizable compound, for example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (Organic Electronics Materials Research) Edited by “Organic Materials for Imaging”, Bunshin Publishing (1993), pages 187-192).
Examples of the cationic polymerization initiator suitable for the present invention are listed below.

That is, first, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium and phosphonium. Can be mentioned. 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.
Such cationic polymerization initiators may be used alone or in combination of two or more.

[(C) Colorant]
The ink composition of the present invention contains (C) a colorant.
The colorant that can be used in the present invention is not particularly limited, but (C-1) pigments and (C-2) oil-soluble dyes that are excellent in weather resistance and rich in color reproducibility are preferable, and are soluble. Any known colorant such as a dye can be selected and used. The colorant that can be suitably used in the ink composition of the present invention is a compound that does not function as a polymerization inhibitor in a polymerization reaction that is a curing reaction, from the viewpoint of not reducing the sensitivity of the curing reaction by actinic radiation. preferable.

(C-1) Pigment The pigment that can be used in the present invention is not particularly limited. For example, organic or inorganic pigments having the following numbers described in the color index can be used.
Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, and 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,
As the blue or cyan pigment, Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17-1, 22, 27, 28, 29, 36, 60 Pigment Green 7, 26, 36, 50,
As the 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,
As the black pigment, Pigment Black 7, 28, 26,
As a white pigment, Pigment White 6, 18, 21
Etc. can be used according to the purpose.

(C-2) Oil-soluble dye The oil-soluble dye that can be used in the present invention is described below.
The oil-soluble dye that can be used in the present invention means a dye that is substantially insoluble in water. Specifically, the solubility in water at 25 ° C. (the mass of the dye that can be dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Accordingly, the oil-soluble dye means a so-called water-insoluble pigment or oil-soluble dye, and among these, an oil-soluble dye is preferable.

  Among the oil-soluble dyes that can be used in the present invention, any yellow dye can be used. For example, phenols, naphthols, anilines, pyrazolones, pyridones, aryl or heteryl azo dyes having open-chain active methylene compounds as coupling components; for example, azomethine dyes having open-chain active methylene compounds as coupling components; Examples include methine dyes such as benzylidene dyes and monomethine oxonol dyes; quinone dyes such as naphthoquinone dyes and anthraquinone dyes; and other dye species such as quinophthalone dyes, nitro / nitroso dyes, and acridines. And dyes and acridinone dyes.

  Among the oil-soluble dyes usable in the present invention, any magenta dye can be used. For example, aryl or hetaryl azo dyes having phenols, naphthols, anilines as coupling components; for example, azomethine dyes having pyrazolones, pyrazolotriazoles as coupling components; for example arylidene dyes, styryl dyes, merocyanine dyes, oxonol dyes Methine dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes and xanthene dyes; quinone dyes such as naphthoquinone, anthraquinone and anthrapyridone; condensed polycyclic dyes such as dioxazine dyes, etc. Can be mentioned.

  Among the oil-soluble dyes applicable to the present invention, any cyan dye can be used. For example, indoaniline dyes, indophenol dyes or azomethine dyes having pyrrolotriazoles as coupling components; polymethine dyes such as cyanine dyes, oxonol dyes, merocyanine dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes Phthalocyanine dyes; anthraquinone dyes; for example, aryl or heteryl azo dyes having phenols, naphthols and anilines as coupling components; indigo / thioindigo dyes;

  Each of the above dyes may exhibit yellow, magenta, and cyan colors only after a part of chromophore (chromogenic atomic group) is dissociated. In this case, the counter cation may be an alkali metal or ammonium. Such inorganic cations may be used, and organic cations such as pyridinium and quaternary ammonium salts may be used, and furthermore, polymer cations having such a partial structure may be used.

Although not limited to the following, preferred specific examples include C.I. I. Solvent Black 3, 7, 27, 29 and 34; C.I. I. Solvent Yellow 14, 16, 19, 29, 30, 56, 82, 93 and 162; C.I. I. Solvent Red 1, 3, 8, 18, 24, 27, 43, 49, 51, 72, 73, 109, 122, 132 and 218; I. Solvent Violet 3; C.I. I. Solvent Blue 2,11,25,35,38,67 and 70; I. Solvent Green 3 and 7; I. Solvent orange 2; and the like.
Among these, particularly preferred are the Black Black PC-0850, Oil Black HBB, Oil Yellow 129, Oil Yellow 105, Oil Pink 312, Oil Red 5B, Oil Scallet 308, Vali Fast Blue chemistry 2606e Bile 2OSe 2B eO (Manufactured by Co., Ltd.), Aizen Spillon Blue GNH (manufactured by Hodogaya Chemical Co., Ltd.), Neopen Yellow 075, Neopen Magenta SE1378, Neopen Blue 808, Neopen Blue FF4012, and Neo42 Cy FF4012.
In the present invention, the oil-soluble dye may be used alone or in combination of several kinds.

Moreover, when using an oil-soluble dye as a colorant, other water-soluble dyes, disperse dyes, pigments, and other colorants can be used in combination as long as the effects of the present invention are not impaired.
In the present invention, a disperse dye can be used as long as it is soluble in a water-immiscible organic solvent. The disperse dye generally includes a water-soluble dye, but in the present invention, the disperse dye is preferably used as long as it is soluble in a water-immiscible organic solvent. Preferable specific examples of the disperse dye include C.I. I. Disperse Yellow 5,42,54,64,79,82,83,93,99, 100,119,122,124,126,160,184: 1,186,198,199,201,204,224 and 237 C. I. Disperse Orange 13, 29, 31: 1, 33, 49, 54, 55, 66, 73, 118, 119 and 163; I. Disperse Red 54, 60, 72, 73, 86, 88, 91, 92, 93, 111, 126, 127, 134, 135, 143, 145, 152, 153, 154, 159, 164, 167: 1,177 , 181, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356 and 362; I. Disperse Violet 33; C.I. I. Disperse Blue 56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 185, 197, 198, 201, 214, 224, 225 , 257, 266, 267, 287, 354, 358, 365 and 368; I. Disperse Green 6: 1 and 9;

  The colorant that can be used in the present invention is preferably appropriately dispersed in the ink after being added to the ink composition of the present invention. For dispersing the colorant, 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 colorant. 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. In the present invention, these dispersant and dispersion aid are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the colorant.

  In preparing the ink composition of the present invention, the colorant may be blended directly with each component by addition. However, in order to improve dispersibility, a solvent or (B) a polymerizable compound used in the present invention is used in advance. It can also be added after being added to the dispersion medium and uniformly dispersed or dissolved.

  In the present invention, in order to avoid the problem of deterioration of solvent resistance when the solvent remains in the cured image and the problem of VOC (Volatile Organic Compound) of the remaining solvent, the colorant is (B) polymerization. It is preferable to add to the active compound in advance. In consideration of only dispersibility, it is preferable to select a monomer having the lowest viscosity as the polymerizable compound used for the addition of the colorant.

  These colorants may be used by appropriately selecting one type or two or more types according to the purpose of use of the ink composition.

  When using a colorant such as a pigment that remains solid in the ink composition of the present invention, the average particle diameter of the colorant particles is preferably 0.005 to 0.5 μm, more preferably 0. It is preferable to set the colorant, dispersant, dispersion medium selection, dispersion conditions, and filtration conditions so as to be 0.01 to 0.45 μm, more preferably 0.015 to 0.4 μm. This particle size control is preferable because clogging of the head nozzle can be suppressed and ink storage stability, ink transparency, and curing sensitivity can be maintained.

  The content of the colorant in the ink composition of the present invention is appropriately selected depending on the purpose of use. However, considering the ink physical properties and colorability, generally, the content of the colorant is 1 to 10 with respect to the total mass of the ink composition. It is preferable that it is mass%, and it is more preferable to contain 2-8 mass%.

In the ink composition of the present invention, in addition to the essential components described above, other components can be used in combination for the purpose of improving physical properties as long as the effects of the present invention are not impaired.
Hereinafter, these optional components will be described below.

[(E) Sensitizing dye]
To the ink composition of the present invention, (E) a sensitizing dye can be added in order to promote the decomposition of the polymerization initiator (A) by irradiation with actinic rays. A sensitizing dye absorbs specific actinic radiation and enters an electronically excited state. The sensitizing dye in an electronically excited state is brought into contact with the polymerization initiator to cause actions such as electron transfer, energy transfer, and heat generation, thereby causing a chemical change of the polymerization initiator, that is, decomposition, radical, acid or base. It promotes the generation of.

As the sensitizing dye, a compound corresponding to the wavelength of actinic radiation that generates an initiating species in the polymerization initiator (A) used in the ink composition may be used, but it is used for a curing reaction of a general ink composition. In view of the above, 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 (for example, thionine, methylene blue, toluidine blue), acridines (for example, acridine orange, chloroflavin, acriflavine), anthraquinones (for example, anthraquinone), squalium (for example, squalium) ), Coumarins (for example, 7-diethylamino-4-methylcoumarin), and the like.

  More preferable examples of the sensitizing dye include compounds represented by the following formulas (II) to (VI).

(In the formula (II), A ¹ represents a sulfur atom or NR ⁵⁰ , R ⁵⁰ represents an alkyl group or an aryl group, and L ² represents a basic nucleus of the dye in combination with the adjacent A ¹ and the adjacent carbon atom. Represents a nonmetallic atomic group to be formed, R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁵¹ and R ⁵² are bonded to each other to form an acidic nucleus of the dye. W represents an oxygen atom or a sulfur atom.)

(In the formula (III), 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 is synonymous with that shown in Formula (II).)

(In the formula (IV), 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 the formula (V), 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 an unsubstituted aryl group, L ⁵ and L ⁶ each independently represent a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with adjacent A ³ , A ^4, and adjacent carbon atoms; ⁶⁰ and R ⁶¹ are each independently a hydrogen atom or a monovalent nonmetallic atomic group, or can be bonded to each other to form an aliphatic or aromatic ring.

(In the formula (VI), 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 can be bonded to each other to form an aliphatic or aromatic ring. .)

  Preferable specific examples of the compounds represented by formulas (II) to (VI) include those shown below.

[(F) Co-sensitizer]
The ink composition of the present invention can also contain a co-sensitizer. In the present invention, the co-sensitizer has functions such as further improving the sensitivity of the sensitizing dye to actinic radiation or suppressing polymerization inhibition of the polymerizable compound by oxygen.
Examples of such cosensitizers include amines such as M.I. R. Sander et al., “Journal of Polymer Society”, Vol. 10, 3173 (1972), Japanese Patent Publication No. 44-20189, Japanese Patent Publication No. 51-82102, Japanese Patent Publication No. 52-134692, Japanese Patent Publication No. 59-138205. No. 60-84305, JP-A 62-18537, JP-A 64-33104, Research Disclosure 33825, and the like. Specific examples include triethanolamine. P-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like.

  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-5-142773, 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-H described in JP-A-8-65779 , Ge—H compounds and the like.

[(G) Other ingredients]
If necessary, other components can be added to the ink composition of the present invention. Examples of other components include a polymerization inhibitor and a solvent.
A polymerization inhibitor may be added from the viewpoint of enhancing the storage stability. Further, when the ink composition of the present invention is used as an ink composition for ink jet recording, it is preferably discharged at a temperature in the range of 40 to 80 ° C. with a reduced viscosity, and also for preventing head clogging due to thermal polymerization. It is preferable to add a polymerization inhibitor. The polymerization inhibitor is preferably added in an amount of 200 to 20,000 ppm based on the total amount of the ink composition 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 composition of the present invention is a radiation curable ink composition, it is preferable that no solvent is contained so that the ink composition can react quickly and cure immediately after landing of the ink composition. However, a predetermined solvent can be included as long as the curing rate of the ink composition is not affected. In the present invention, as the solvent, an organic solvent may be used, water from the viewpoint of the curing rate is not added pressure. An organic solvent can be added in order to improve adhesion to a recording medium (a support such as paper).
The amount of the organic solvent is, for example, 0.1 to 5% by mass, preferably 0.1 to 3% by mass with respect to the mass of the entire ink composition of the present invention.

  In addition to this, a known compound can be added to the ink composition 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.

[Properties of ink composition]
The ink composition of the present invention to use as the ink for ink jet recording. The preferable physical property in such a use aspect is demonstrated.
When the ink composition is used as an ink for ink jet recording, the viscosity is preferably 7 to 30 mPa at the temperature at the time of ejection (for example, 40 to 80 ° C., preferably 25 to 50 ° C.) in consideration of the ejectability. · S, more preferably 7 to 25 mPa · s. For example, the viscosity of the ink composition of the present invention at room temperature (25 to 30 ° C.) is preferably 35 to 500 mPa · s, more preferably 35 to 200 mPa · s.
It is preferable that the composition ratio of the ink composition of the present invention is appropriately adjusted 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 composition of the present invention is preferably 20 to 30 mN / m, more 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.

<Inkjet recording method>
The ink jet recording method of the present invention and the ink jet recording apparatus applicable to the ink jet recording method will be described below.
The inkjet recording method of the present invention, a recording medium (support, recording material, etc.) the inkjet recording ink composition of the present invention discharged on the active radiation to the ink composition discharged onto the recording medium irradiated Then, the ink is cured to form an image.

That is, the ink jet recording method of the present invention comprises (a) a step of ejecting the ink composition for ink jet recording of the present invention onto a recording medium, and (b) irradiating the ejected ink composition with actinic radiation. And a step of curing the ink composition.
By including the steps (a) and (b), the ink jet recording method of the present invention forms an image with the ink composition cured on the recording medium.

  In the step (a) in the inkjet recording method of the present invention, an inkjet recording apparatus described in detail below can be used.

[Inkjet recording device]
There is no restriction | limiting in particular as an inkjet recording device used for the inkjet recording method of this invention, The well-known inkjet recording device which can achieve the target resolution can be selected arbitrarily and can be used. That is, any known inkjet recording apparatus including a commercially available product can eject ink onto a recording medium in step (a) of the inkjet recording method of the present invention.
Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system, a temperature sensor, and an actinic radiation source.
The ink supply system includes, for example, an original tank containing the ink composition of the present invention, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet 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 discharge 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, like the ink composition of the present invention, has a constant temperature for the ink to be ejected, heat insulation and heating are performed from the ink supply tank to the inkjet head portion. It can be carried out. 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 near 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 heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

Using the above inkjet recording apparatus, the ink composition of the present invention is ejected by heating the ink composition to 40 to 80 ° C., more preferably 25 to 50 ° C. Preferably it is performed after lowering to 7-30 mPa · s, more preferably 7-25 mPa · s. In particular, it is preferable to use an ink composition having an ink viscosity at 25 ° C. of 35 to 500 mPa · s as the ink composition of the present invention because a large effect can be obtained. By using this method, high ejection stability can be realized.
A radiation curable ink composition such as the ink composition of the present invention generally has a higher viscosity than a water-based ink usually used in ink jet recording inks, and therefore has a large viscosity fluctuation due to temperature fluctuations during ejection. The ink viscosity fluctuation has a great influence on the change of the droplet size and the change of the droplet discharge speed, and causes the image quality deterioration. Therefore, it is necessary to keep the temperature of the ink at the time of ejection as constant as possible. Therefore, in the present invention, it is appropriate that the control range of the ink temperature is ± 5 ° C. of the set temperature, preferably ± 2 ° C. of the set temperature, more preferably ± 1 ° C. of the set temperature.

Next, (b) the step of irradiating the ejected ink composition with actinic radiation to cure the ink composition will be described.
The ink composition ejected on the recording medium is cured by irradiation with actinic radiation. This is because (A) the polymerization initiator contained in the ink composition of the present invention is decomposed by irradiation with actinic radiation to generate initiating species such as radicals, acids, bases, and the like (B This is because the polymerization reaction of the polymerizable compound occurs and is accelerated. At this time, if (E) a sensitizing dye is present together with (A) the polymerization initiator in the ink composition, (E) the sensitizing dye in the system absorbs actinic radiation and becomes excited, and (A) the polymerization initiator. By contacting with (A), the decomposition of the polymerization initiator can be promoted, and a more sensitive curing reaction can be achieved.

  Here, α rays, γ rays, electron beams, X rays, ultraviolet rays, visible light, infrared rays, or the like can be used as the active radiation used. Although the peak wavelength of actinic radiation is based also on the absorption characteristic of a sensitizing dye, it is preferable that it is 200-600 nm, for example, it is more preferable that it is 300-450 nm, and it is still more preferable that it is 350-420 nm.

In addition, the polymerization initiation system of the ink composition of the present invention has sufficient sensitivity even with a low output actinic radiation. Thus, the output of the active radiation is preferably 2,000 mJ / cm ² or less, more preferably from 10 to 2,000 mJ / cm ^2, more preferably be 20 to 1,000 mJ / cm ² Particularly preferably, it is 50 to 800 mJ / cm ² .
Furthermore, the actinic radiation is, the exposure surface illuminance of, for example, 10 to 2,000 mW / cm ^2, preferably, suitably be irradiated at 20 to 1,000 mW / cm ^2.

Mercury lamps and gas / solid lasers are mainly used as actinic radiation sources, and mercury lamps and metal halide lamps are widely known as light sources used for curing UV photocurable ink jet recording inks. Yes. 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 photo-curable ink jets.
Further, a light emitting diode (LED) and a laser diode (LD) can be used as the active 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 introduced 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 actinic radiation centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. The actinic radiation source particularly preferred in the present invention is a UV-LED, particularly preferably a UV-LED having a peak wavelength at 350 to 420 nm.
Incidentally, it is preferable that maximum illumination intensity of the LED on a recording medium is 10 to 2,000 mW / cm ^2, more preferably 20 to 1,000 mW / cm ^2, particularly preferably 50 to 800 mW / cm ² .

The ink composition of the present invention is suitably irradiated with such actinic radiation for, for example, 0.01 to 120 seconds, preferably 0.1 to 90 seconds.
Actinic 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 with actinic 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 the porous recording medium before the ink penetrates to a deep part where the light source does not reach, the residual unreacted monomer can be suppressed, and as a result, the odor can be reduced. .
Further, the curing may be completed by another light source that is not driven. WO99 / 54415 pamphlet discloses a method using an optical fiber and a method of applying a collimated light source to a mirror surface provided on the side surface of the head unit and irradiating the recording unit with UV light as an irradiation method. The curing method can also be applied to the ink jet recording method of the present invention.

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. In addition, irradiation can be performed by discharging all colors and collectively exposing, but exposure for each color is preferable from the viewpoint of promoting curing.
In this manner, the ink composition of the present invention can form an image on the surface of a recording medium by being cured with high sensitivity by irradiation with actinic radiation.

<Lithographic printing plate and manufacturing method thereof>
A lithographic printing plate can be produced by applying the ink composition for ink- jet recording of the present invention on a hydrophilic support and curing it using the ink-jet recording method of the present invention.
Hereinafter, a method for producing a lithographic printing plate (a method for producing a lithographic printing plate of the present invention) to which the inkjet recording method of the present invention is applied, and a lithographic printing plate obtained by the method (lithographic printing plate of the present invention) will be described.

The lithographic printing plate of the present invention has a hydrophilic support and a hydrophobic image formed on the hydrophilic support. This method for producing a lithographic printing plate includes the following steps.
(A ′) a step of discharging the ink composition for inkjet recording of the present invention onto a hydrophilic support; and (b ′) irradiating the discharged ink composition with actinic radiation to cure the ink composition. In this step, a hydrophobic image formed by curing the ink composition is formed on the hydrophilic support.
That is, a lithographic printing plate can be produced in the same manner as in the ink jet recording method of the present invention except that a support having a hydrophilic surface suitable for a lithographic printing plate support is used as the recording medium. .

Conventionally, a lithographic printing plate is obtained by exposing a so-called PS plate having a structure in which a lipophilic photosensitive resin layer is provided on a hydrophilic support as described above, and solubilizing or curing the exposed portion. It was manufactured by forming an image and dissolving and removing non-image areas.
On the other hand, the lithographic printing plate of the present invention is applied directly to the surface of the hydrophilic support according to the digitized image information by applying the lithographic printing plate production method of the present invention (inkjet recording method of the present invention). A hydrophobic image portion can be formed by injecting an object and curing it. This makes it possible to produce a lithographic printing plate more easily than in the past.

[Hydrophilic support used for lithographic printing plates]
The lithographic printing plate of the present invention has a hydrophilic support and a hydrophobic image formed on the surface of the support by the ink composition of the present invention.

The lithographic printing plate support (recording medium) onto which the ink composition of the present invention is discharged is not particularly limited, and any dimensionally stable plate-like support can be used. However, in consideration of the image quality of the obtained printed matter, the surface is preferably a hydrophilic support.
The material used as the support can be used as the support as it is when it has hydrophilicity, and when it does not have hydrophilicity, the surface thereof may be subjected to water immersion treatment.
Materials used for the support include, 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.), paper or plastic film on which the above-mentioned metal is laminated or vapor-deposited, etc. Is mentioned. A preferable support includes 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 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. However, since completely pure aluminum is difficult to manufacture in terms of refining technology, it 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 0.1 to 0.6 mm, and more preferably 0.15 to 0.4 mm.
Prior to using the aluminum plate, it is preferable to perform surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it becomes easy to improve hydrophilicity and secure adhesion between the hydrophobic image 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, which is preferable.

  As the support used in the present invention, a substrate that has been surface-treated as described above and has an anodized film may be used as it is. However, adhesion to a hydrophobic image, hydrophilicity, stain resistance, etc. are further improved. In order to improve, if necessary, the micropore enlargement treatment or sealing treatment of the anodized film described in JP-A-2001-253181 and JP-A-2001-322365, and a hydrophilic compound are contained. A surface hydrophilization treatment immersed in an aqueous solution can be selected as appropriate. Of course, the enlargement process and the sealing process 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.
Among these, a sealing treatment with an aqueous solution containing an inorganic fluorine compound, a sealing treatment with water vapor, and a sealing treatment with hot water are preferable. Each will be described below.

-Sealing treatment with aqueous solution containing 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. Among 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, and more preferably 0.05% by mass or more in terms of sufficiently sealing the micropores of the anodized film. Further, in terms of stain resistance, the content is preferably 1% by mass or less, and more preferably 0.5% by mass or less.
It is preferable that the aqueous solution containing the 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, which is preferable.

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. Among 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. It is preferable.
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, in terms of improvement in on-press developability and stain resistance. Moreover, it is preferable that it is 20 mass% or less at a soluble point, and it is more preferable that it is 5 mass% or less.

The ratio of each compound in the aqueous solution is not particularly limited, but the mass ratio of the inorganic fluorine compound and the phosphate compound is preferably 1/200 to 10/1, and preferably 1/30 to 2/1. Is more preferable.
The temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, 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 processing using the dipping method, the processing time is preferably 1 second or longer, more preferably 3 seconds or longer, 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 pressure of the water vapor 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).
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, and more preferably 20 seconds or shorter.

-Sealing treatment with hot water-
Examples of the sealing treatment with hot water (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, 100 seconds or shorter, more preferably 20 seconds or shorter.

  As the hydrophilization treatment for the support in the present invention, U.S. Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734 are each used. There are alkali metal silicate methods as described in the specification. 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 polyvinylphosphonic acid as described in each specification of No.272.

  In the present invention, the support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to a hydrophobic image, good printing durability and good stain resistance are obtained, which is preferable.

(A ′) Step of discharging the ink composition for ink jet recording of the present invention onto a hydrophilic support First, the ink composition for ink jet recording of the present invention is discharged onto a hydrophilic support. In this step, a conventionally known ink jet recording apparatus can be used in the same manner as described in the ink jet recording method. In addition, when ink is ejected using this ink jet recording apparatus, preferred ranges of ink temperature and viscosity, and the control methods thereof are also the same.

(B ′) a step of forming a hydrophobic image formed by curing the ink composition by irradiating the ejected ink composition with actinic radiation, and the surface of the hydrophilic support The ink composition discharged above is cured by irradiation with actinic radiation. The details of the curing mechanism are the same as those described in the ink jet recording method. Further, the actinic radiation source used for curing the ink composition or the preferable irradiation condition thereof is also the same as described in the ink jet recording method.

Through the above steps, a hydrophobic image formed by curing the ink composition for ink jet recording of the present invention is formed on the surface of the hydrophilic support, and a lithographic printing plate is obtained.

In this way, by applying the inkjet recording method of the present invention to produce a lithographic printing plate, the dot diameter of the landed ink is constant even for various lithographic printing plate supports having different surface wettability. As a result, a hydrophobic image can be accurately formed.
Further, as described above, the ink composition of the present invention can be cured with high sensitivity by actinic radiation, and can form a hydrophobic region (hydrophobic image) excellent in adhesion to the support and film quality.
For these reasons, the planographic printing plate of the present invention has high image quality and excellent printing durability.
In addition, it cannot be overemphasized that the ink composition of this invention is useful not only as an image part of such a lithographic printing plate but also as a generally used ink composition.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the embodiments in these examples.
The following examples relate to UV inkjet inks of each color.

[Example 1]
The following components were stirred with a high-speed water-cooled stirrer to obtain a cyan UV inkjet ink.
(Cyan ink composition)
-(D) Specific polymer: D-4 (weight average molecular weight 50,000) 9.0 parts-(B) NK ester A-NOD-N 55.0 parts (* acrylate monomer manufactured by Shin-Nakamura Chemical Co., Ltd.)
-(B) Photomer 2017 (UV diluent made by EChem) 14.4 parts-Solsperse 32000 (dispersant made by Noveon) 0.4 parts-(C) Irgalite Blue GLVO 3.6 parts (pigment made by Ciba Specialty Chemicals) )
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 parts ・ (A) Lucirin TPO (photopolymerization initiator manufactured by BASF) 8.5 parts ・ (A) benzophenone (photopolymerization initiator) 4.0 parts ・ ( A) Irgacure 184 4.0 parts (photopolymerization initiator manufactured by Ciba Specialty Chemicals)
-(A) 2,4-diethylthioxanthone 1.0 part-Byk 307 (antifoam manufactured by BYK Chemie) 0.05 part

  Here, * NK ester A-NOD-N is 1,9-nonanediol diacrylate (bifunctional acrylate).

(Evaluation of ink)
The resulting cyan ink composition is printed on a polyvinyl chloride sheet and irradiated by passing it through an iron-doped UV lamp (power 60 W / cm ² ) at a speed of 20 m / min. The ink was cured to obtain a printed matter.

At this time, the following evaluation was performed.
The exposure energy in curing was measured with a light quantity integrator (UV PowerMAP manufactured by EIT). As a result, the cumulative exposure amount of ultraviolet rays on the sheet was about 330 mJ / cm ² , and it was confirmed that the sheet was cured with high sensitivity.

  The curability was evaluated by palpation of the image area after the printed material was cured with this ink. As a result, it was confirmed that the tackiness after curing was completely lost and the curability was excellent.

The adhesion to the recording medium was evaluated by a cross hatch test. As a result, high adhesiveness of class 4B was shown.
The cross-hatch test is based on ISO 2409 (ASTM D 3359), and the cured film is cross-cut at 25 stitches at intervals of 2.0 mm (6 cuts in length and width). : Scotch tape (3M600), manufactured by Sumitomo 3M Co., Ltd.) was strongly attached, and then the adhesive tape was rapidly peeled off to examine the presence or absence of peeling of the cured film.

Further, the flexibility was evaluated by the degree of cracks generated in the cured film after bending the sheet 10 times. This bending test was performed in a five-step evaluation (sensory evaluation) with 5 points indicating a state in which no cracks occurred, and 3 or more points were evaluated as having no practical problems. As a result, the cured film was evaluated as 3 points only with the occurrence of slight cracks that did not affect the printed image.
The results are shown in Table 1 below.

(Example 2)
The following components were stirred with a high-speed water-cooled stirrer to obtain a magenta UV inkjet ink.
(Magenta ink composition)
-(D) Specific polymer: D-1 (weight average molecular weight 10,000) 3.0 parts-(B) NK ester A-NOD-N 35.0 parts (the acrylate monomer manufactured by Shin-Nakamura Chemical Co., Ltd.)
-(B) Actilane 422 21.4 parts (*: acrylate monomer manufactured by Akcros)
-(B) Photomer 2017 (UV diluent manufactured by EChem) 16.0 parts-Solsperse 32000 (dispersant made by Noveon) 0.4 parts-(C) Cinquasia Magenta RT-355D 3.6 parts (Ciba Specialty Chemicals) Pigment)
・ Genorad 16 (Rahn Stabilizer) 0.05 part (B) Rapi-Cure DVE-3 3.0 part (ISP Europe Corp. vinyl ether)
・ (A) Lucirin TPO (for photopolymerization initiator manufactured by BASF) 8.5 parts ・ (A) Benzophenone (photopolymerization initiator) 4.0 parts ・ (A) Irgacure 184 4.0 parts (Ciba Specialty Chemicals) Photopolymerization initiator)
-Byk 307 (antifoaming agent manufactured by BYK Chemie) 0.05 parts * Activane 422 is dipropylene glycol diacrylate (bifunctional acrylate).

The resulting magenta color ink was printed on a polyvinyl chloride sheet and irradiated by passing it through an iron-doped UV lamp (power 60 W / cm ² ) at a speed of 20 m / min. . The printed matter with this ink was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Example 3
The following components were stirred with a high-speed water-cooled stirrer to obtain a yellow UV inkjet ink.
(Yellow color ink composition)
-(D) Specific polymer: D-5 (weight average molecular weight 8,000) 18.0 parts-(B) NK ester A-NOD-N 41.4 parts (the acrylate monomer manufactured by Shin-Nakamura Chemical Co., Ltd.)
・ (B) Photomer 2017 (UV diluent manufactured by EChem) 18.0 parts ・ Solsperse 32000 (dispersant made by Noveon) 0.4 parts ・ (C) Chromophthalmic Yellow LA 3.6 parts (pigment manufactured by Ciba Specialty Chemicals) )
・ Genorad 16 (Rahn Stabilizer) 0.05 part (B) Rapi-Cure DVE-3 2.0 part (ISP Europe vinyl ether)
-(A) Lucirin TPO (BASF photopolymerization initiator) 8.5 parts-(A) Benzophenone (photopolymerization initiator) 4.0 parts-(A) Irgacure 184 4.0 parts (Ciba Specialty Chemicals) Photopolymerization initiator)
・ Byk 307 (defoamer manufactured by BYK Chemie) 0.05 parts

The resulting yellow ink was printed on a polyvinyl chloride sheet and irradiated by passing it through an iron-doped UV lamp (power 60 W / cm ² ) at a speed of 20 m / min. . The printed matter with this ink was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Example 4
The following components were stirred with a high-speed water-cooled stirrer to obtain a black UV inkjet ink.
(Black ink composition)
-(D) Specific polymer: D-4 (weight average molecular weight 22,000) 12.0 parts-(B) NK ester A-NOD-N 50.4 parts (the acrylate monomer manufactured by Shin-Nakamura Chemical Co., Ltd.)
・ (B) Photomer 2017 (UV diluent manufactured by EChem) 16.0 parts ・ Solsperse 32000 (dispersant manufactured by Noveon) 0.4 parts ・ (C) 2.6 parts of Microlith Black C-K (Ciba Specialty Chemicals) Pigment)
・ Genorad 16 (Rahn Stabilizer) 0.05 part (B) Rapi-Cure DVE-3 2.0 part (ISP Europe vinyl ether)
-(A) Lucirin TPO (BASF photopolymerization initiator) 8.5 parts-(A) Benzophenone (photopolymerization initiator) 4.0 parts-(A) Irgacure 184 4.0 parts (Ciba Specialty Chemicals) Photopolymerization initiator)
・ Byk 307 (defoamer manufactured by BYK Chemie) 0.05 parts

The resulting black ink was printed on a polyvinyl chloride sheet and irradiated by passing it through an iron-doped UV lamp (power 60 W / cm ² ) at a speed of 20 m / min. The printed matter with this ink was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

(Example 5)
The following components were stirred with a high-speed water-cooled stirrer to obtain a cyan UV inkjet ink.
(Cyan ink composition)
-(D) Specific polymer: D-3 (weight average molecular weight 7,000) 4.0 parts-(B) Actilane 422 75.4 parts (the acrylate monomer manufactured by Akcros)
Solsperse 32000 (Noveon's dispersant) 0.4 parts (C) Irgalite Blue GLVO 3.6 parts (Ciba Specialty Chemicals pigment)
-Genorad 16 (stabilizer manufactured by Rahn) 0.05 part-(B) Rapi-Cure DVE-2 2.0 parts (vinyl ether manufactured by ISP Europe)
・ (A) Lucirin TPO (BASF photopolymerization initiator) 8.5 parts ・ (A) Benzophenone (photopolymerization initiator: component) 4.0 parts ・ (A) Irgacure 184 4.0 parts (Ciba Specialty Chemicals) Photopolymerization initiator)
・ Byk 307 (defoamer manufactured by BYK Chemie) 0.05 parts

The obtained cyan ink was printed on a polyvinyl chloride sheet and irradiated by passing it through a light beam of an iron-doped ultraviolet lamp (power 60 W / cm ² ) at a speed of 20 m / min. . The printed matter with this ink was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

(Comparative Example 1)
The following components were stirred with a high-speed water-cooled stirrer to obtain a cyan UV inkjet ink.
(Cyan ink composition)
・ (B) NK Ester A-NOD-N 64.0 parts (* Acrylic monomer manufactured by Shin-Nakamura Chemical Co., Ltd.)
-(B) Photomer 2017 (UV diluent made by EChem) 14.4 parts-Solsperse 32000 (dispersant made by Noveon) 0.4 parts-(C) Irgalite Blue GLVO 3.6 parts (pigment made by Ciba Specialty Chemicals) )
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 parts ・ (A) Lucirin TPO (photopolymerization initiator manufactured by BASF) 8.5 parts ・ (A) benzophenone (photopolymerization initiator) 4.0 parts ・ ( A) Irgacure 184 4.0 parts (photopolymerization initiator manufactured by Ciba Specialty Chemicals)
-(A) 2,4-diethylthioxanthone 1.0 part-Byk 307 (antifoam manufactured by BYK Chemie) 0.05 part

The obtained cyan ink was printed on a polyvinyl chloride sheet and irradiated by passing it through a light beam of an iron-doped ultraviolet lamp (power 60 W / cm ² ) at a speed of 20 m / min. . The printed matter with this ink was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

  As is apparent from Table 1, the ink compositions of Examples 1 to 5 were all cured with high sensitivity, and any of the curability of the image area, the adhesion to the recording medium, and the flexibility of the image (film) It was also excellent. On the other hand, (D) The ink composition of Comparative Example 1 containing no specific polymer was inferior in curability and could not be evaluated for adhesion and flexibility.

(Example 7)
<Production of support>
Si: 0.06 mass%, Fe: 0.30 mass%, Cu: 0.025 mass%, Mn: 0.001 mass%, Mg: 0.001 mass%, Zn: 0.001 mass%, Ti: It contains 0.03% by mass, and the balance is prepared by using an aluminum alloy of Al and inevitable impurities. After the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by a DC casting method. Produced. After the surface was shaved with a chamfering machine with an average thickness of 10 mm, it was kept soaked at 550 ° C. for about 5 hours, and when the temperature dropped to 400 ° C., rolling with a thickness of 2.7 mm using a hot rolling mill A board was used. Furthermore, after performing heat processing using a continuous annealing machine at 500 degreeC, it finished by cold rolling to 0.24 mm in thickness, and obtained the aluminum plate of JIS1050 material. The obtained aluminum had an average crystal grain size with a minor axis of 50 μm and a major axis of 300 μm. After making this aluminum plate width 1030mm, it used for the surface treatment shown below and created the aluminum support body.

<Surface treatment>
In the surface treatment, the following various treatments (a) to (j) were continuously performed. In addition, after each process and water washing, the liquid draining was performed with the nip roller.

(A) Mechanical surface roughening treatment While supplying a suspension of a polishing agent (pumice) having a specific gravity of 1.12 and water as a polishing slurry liquid to the surface of the aluminum plate, mechanical roughening is performed by a rotating nylon brush. Surface treatment was performed. The average particle size of the abrasive was 30 μm, and the maximum particle size was 100 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 45 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkali etching treatment The aluminum plate obtained above was subjected to an etching treatment by spraying using an aqueous solution having a caustic soda concentration of 2.6% by mass, an aluminum ion concentration of 6.5% by mass and a temperature of 70 ° C. / M ² dissolved. Then, water washing by spraying was performed.

(C) Desmutting treatment The desmutting treatment was performed by spraying with a 1% by mass aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by mass of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut treatment was a waste liquid from a process of performing an electrochemical surface roughening treatment using alternating current in a nitric acid aqueous solution.

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 10.5 g / L aqueous solution of nitric acid (containing 5 g / L of aluminum ions and 0.007% by mass of ammonium ions) at a liquid temperature of 50 ° C. AC power supply waveform is 0.8 msec until the current value reaches the peak from zero, duty ratio is 1: 1, and trapezoidal rectangular wave alternating current is used to perform electrochemical surface roughening treatment with the carbon electrode as the counter electrode. went. Ferrite was used for the auxiliary anode.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Then, water washing by spraying was performed.

(E) Alkaline etching treatment The aluminum plate was subjected to etching treatment at 32 ° C. using an aqueous solution having a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass to dissolve the aluminum plate by 0.50 g / m ² . Removes the smut component mainly composed of aluminum hydroxide that was generated when electrochemical roughening treatment was performed using the alternating current of the previous stage, and also melted the edge part of the generated pit to smooth the edge part. did. Then, water washing by spraying was performed.

(F) Desmut treatment Desmut treatment was performed by spraying with a 15% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 4.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used in the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in the nitric acid aqueous solution.

(G) Electrochemical roughening treatment An electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 5.0 g / L aqueous solution (containing 5 g / L of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform is subjected to electrochemical surface roughening using a carbon electrode as a counter electrode, using a trapezoidal trapezoidal wave alternating current with a time until the current value reaches a peak from zero for 0.8 msec, a duty ratio of 1: 1. went. Ferrite was used for the auxiliary anode.
The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. Then, water washing by spraying was performed.

(H) Alkali etching treatment An aluminum plate was sprayed at 32 ° C. using an aqueous solution having a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass to dissolve the aluminum plate by 0.12 g / m 2. The smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening treatment using AC was removed, and the edge part of the generated pit was melted to smooth the edge part. . Then, water washing by spraying was performed.

(I) Desmutting treatment A desmutting treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid at a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

(J) Anodizing treatment Anodizing treatment is performed using an anodizing apparatus (first and second electrolysis section length 6 m, first and second feeding section length 3 m, first and second feeding section length 2.4 m each). It was. Sulfuric acid was used as the electrolytic solution supplied to the first and second electrolysis units. All electrolytes had a sulfuric acid concentration of 50 g / L (containing 0.5 mass% of aluminum ions) and a temperature of 20 ° C. Then, water washing by spraying was performed. The final oxide film amount was 2.7 g / m ² .

(Preparation and evaluation of lithographic printing plates)
Printing was performed with the ink composition of Example 5 on the aluminum support prepared above, and an image was formed and cured in the same manner as in Example 5.
Using this as a lithographic printing plate, image evaluation and printing durability evaluation were performed by the following methods.

a. Evaluation of Image A lithographic printing plate produced using the ink composition of Example 5 was applied to a Heidel KOR-D machine and dampened with ink [VALUES-G Beni for Sheet-fed (Dainippon Ink Co., Ltd.)]. Water [Ecocity 2 (Fuji Photo Film Co., Ltd.)] was supplied for printing. The printed matter after printing 100 sheets was visually evaluated. As a result, it was confirmed that the image was a good image with no white spots in the image area and no stain in the non-image area.

b. Evaluation of printing durability When printing is continued as it is, 5,000 or more high-quality prints free from white spots in the image area and stains in the non-image area are obtained, and the printing durability is at a level that does not cause any practical problems. I confirmed that there was.

Claims (10)

(A) a polymerization initiator, (B) a polymerizable compound, containing a polymer compound having a repeating unit represented by (C) a colorant, and (D) the following formula (I), Yuse containing water In addition, the ink composition for ink jet recording is characterized in that it contains 0.5 to 5% by mass relative to the total mass of the ink composition when it does not contain an organic solvent or contains an organic solvent. .

(In general formula (I), n represents an integer of 1 to 5)   The ink composition for ink jet recording according to claim 1, wherein the polymerization initiator (A) is at least one selected from aromatic ketones and acylphosphine compounds.   The ink composition for ink jet recording according to claim 1, comprising two or more kinds of the polymerizable compound (B).   The ink composition for inkjet recording according to any one of claims 1 to 3, wherein the colorant (C) is a pigment.   The ink composition for inkjet recording according to any one of claims 1 to 4, further comprising (E) a sensitizing dye.   The content of the polymer compound having a repeating unit represented by (D) the following general formula (I) is in the range of 1 to 20% by mass with respect to the mass of the whole ink composition. Item 6. The ink composition for ink jet recording according to any one of Items 5.   The ink composition for inkjet recording according to any one of claims 1 to 6, wherein n in the general formula (I) is 4. (A) a step of discharging the ink composition for inkjet recording according to any one of claims 1 to 7 onto a recording medium; and
(B) irradiating the discharged ink composition with actinic radiation to cure the ink composition;
An inkjet recording method comprising: (A ′) a step of discharging the ink composition for inkjet recording according to any one of claims 1 to 7 onto a hydrophilic support; and
(B ′) The discharged ink composition is irradiated with actinic radiation to cure the ink composition, thereby forming a hydrophobic image formed by curing the ink composition on the hydrophilic support. Process,
A method for producing a lithographic printing plate comprising   A lithographic printing plate produced by the method for producing a lithographic printing plate according to claim 9.