JP4799981B2 - 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 even 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 device 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.

  Ink compositions that can be cured by irradiation with actinic radiation such as ultraviolet rays (radiation curable ink compositions), such as ink compositions for ink jet recording, can be cured with high sensitivity and form high-quality images. It has been demanded. By achieving high sensitivity, high curability is imparted by irradiation with actinic radiation, so that sufficient curing is achieved in addition to reducing power consumption and extending life by reducing the load on the actinic radiation generator. As a result, there are various advantages such as suppression of volatilization of uncured low molecular weight substances and reduction in the strength of the formed image. Further, the improvement in the image strength by increasing the sensitivity results in high printing durability in the image area when this ink composition is used for forming the image area of a lithographic printing plate.

  The curable inkjet method using ultraviolet light has been attracting attention in recent years because it has a relatively low odor and can record on a recording medium having no quick drying and no ink absorption. In particular, benzyl, benzoin, benzoin ethyl ether, Michler ketone, anthraquinone, acridine, phenazine, benzophenone, 2-ethylanthraquinone, and the like have been generally used as photopolymerization initiators (for example, see Non-Patent Document 1). However, when these photopolymerization initiators are used, it takes a long time for image exposure in image formation because the photopolymerizable composition has low curing sensitivity. Therefore, in the case of a fine image, if there is a slight vibration in the operation, an image with good image quality cannot be reproduced, and the amount of energy emitted from the light source for exposure must be increased. It was necessary to consider the emission of heat.

  Even for a support that is usually difficult to directly record with an ink jet recording method, it is possible to record an image with no bleeding, high sensitivity, high adhesion to a recording medium, and skin irritation and sensitization. For the purpose of providing an ink composition with low safety and high safety, a composition containing a polymerizable compound consisting of a specific acrylate compound group has been proposed (for example, see Patent Document 1). However, polyfunctional acrylates used for the purpose of improving sensitivity have a three-dimensional structure in which a polymer obtained by curing is highly crosslinked, so that the flexibility and impact resistance after ink curing are reduced, and on the recording medium Cracks and peeling easily occur, and there is a problem in the durability of the formed image.

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 techniques for electronically processing, storing, and outputting image information using a computer have become widespread, and a new image output method corresponding to the technique has been demanded. In particular, 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 (for example, see Patent Document 2). 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.
JP 2003-192943 A JP 54-117203 A Bruce M. Monroe (Bruce M. Monroe et al., Chemical Reviews, Vol. 93, (1993), p. 435-448.

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

As a result of intensive studies, the inventors have improved the flexibility after ink curing while maintaining high sensitivity by using a specific polymerizable compound in the ink composition, The inventors have found that an ink composition with improved particle shape retention and adhesion to a recording medium can be obtained, and the present invention has been completed.
That is, the ink composition of the present invention, (A) a polymerization initiator, (B-1) (meth) acrylic acid, and have a carboxyl group in the molecule one of (meth) acrylate Royle group containing at least one compound selected from the group consisting of an ester or amide, and ester or amide having one (meth) acrylate Royle groups have a (B-2) an alkylene oxide in the molecule the repeating units having It is characterized by doing.

Although the operation of the present invention is not clear, it is estimated as follows.
In the present invention, as the polymerizable compound, (meth) acrylic acid, and have a carboxyl group within the molecule one (meth) one compound selected from the group consisting of esters or amides having an acrylate Royle group When, are used, and ester or amide having one (meth) acrylate Royle group having alkylene oxide repeating units in the molecule. The curing of these polymerizable compounds proceeds, a large number of carboxyl groups and alkylene oxide with low mobility state, will be physically dense. In such a state, the interaction between the carboxyl group and the alkylene oxide is expressed and due to this interaction, inhibited the decrease in cure rate, it is possible to highly sensitive curing by irradiation It is considered a thing.
Also in film after the curing reaction, the interaction between the carboxyl group and alkylene oxide is maintained. Although this interaction itself is weak, since it is densely formed in the film, it is possible to improve the film strength. Similarly, since this interaction is not as strong as when ordinary polyfunctional monomers linked by covalent bonds are used, the film after the curing reaction is a film obtained by curing the polyfunctional monomer. There is also an advantage that it is superior in flexibility.

  When a colored image is formed with this ink composition, a colorant may be further contained. The ink composition of the present invention is suitable for inkjet recording because it is cured with high sensitivity by irradiation and the flexibility of the film formed on the ink surface is improved.

The inkjet recording method according to claim 5 of the present invention includes (a) a step of ejecting the ink composition of the present invention onto a recording medium, and (b) actinic radiation on the ejected ink composition. Irradiating and curing the ink composition.
The method for producing a lithographic printing plate according to claim 6 of the present invention comprises (a) a step of discharging the ink composition of the present invention onto a hydrophilic support, and (b) active on the discharged 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 according to claim 7 is produced by the lithographic printing plate production method 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 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 actinic radiation (especially ultraviolet rays) and the manufacturing method of a planographic printing plate can be provided.

<Ink composition>
The ink composition of the present invention, (A) a polymerization initiator, (B-1) (meth) ester having an acrylic acid, and intramolecular in carboxyl groups possess one (meth) acrylate Royle group or and at least one compound selected from the group consisting of amides, in that it contains, and ester or amide having one (meth) acrylate Royle groups have a (B-2) an alkylene oxide in the molecule the repeating units Features.
The ink composition of the present invention can be suitably used for inkjet recording.
Hereinafter, components essential to the ink composition of the present invention will be sequentially described.

[(B-1) (meth) acrylic acid, and have a carboxyl group in the molecule one (meth) acrylate Royle ester or amide having a group]
The ink composition of the present invention, (meth) acrylic acid, and at least one compound selected from the group consisting of an ester or amide having one (meth) acrylate Royle group have a carboxyl group in the molecule [Hereinafter, it is appropriately referred to as the component (B-1) or a carboxy group-containing polymerizable compound. ] Is contained.
Carboxyl group-containing polymerizable compounds can be used so long as it is a compound having a (meth) or acrylic acid, ester or amide with one or more carboxyl groups of one (meth) acrylic acid in the molecule . The number of carboxyl groups is preferably from 1 to 3 is present in the molecule, more preferably 1-2, particularly preferably 1.
Preferred examples of the carboxy group-containing polymerizable compound include compounds represented by the following general formula (I).

  In the general formula (I), R represents a hydrogen atom or a methyl group, and is preferably a hydrogen atom from the viewpoint of reactivity and flexibility of a polymer produced by a polymerization reaction. X represents an oxygen atom or NR ′ and is preferably an oxygen atom because it improves the mobility around the polymerizable site. Here, R ′ represents a hydrogen atom or an alkyl group, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom. Z represents a divalent organic group, and preferred divalent organic groups include the following.

  Of the compounds represented by acrylic acid, methacrylic acid, and general formula (I), the compound represented by general formula (I) can be more preferably used in the present invention from the viewpoint of handleability such as odor.

  Specific examples [(B-1-1) to (B-1-15)] of the carboxy group-containing polymerizable compound that can be suitably used in the present invention are shown below, but the present invention is not limited thereto. It is not something.

  The content of the (B-1) carboxy group-containing polymerizable compound in the ink composition of the present invention is based on the total mass of the ink composition from the viewpoint of the balance between curing speed and flexibility and ink jet suitability of the ink composition. And the range of 3-25 mass% is preferable, and the range of 5-20 mass% is still more preferable.

[(B-2) have a alkylene oxide repeating units in the molecule an ester or amide having one (meth) acrylate Royle group]
The ink composition of the present invention, (B-1) as a separate essential components and components, esters or amides with intramolecular to have a alkylene oxide repeat units one of (meth) acrylate Royle group [hereinafter appropriately , (B-2) component or alkylene oxide-containing polymerizable compound. ] Is contained.

Here, the alkylene oxide repeating unit means an alkylene oxide represented by —R—O— (R is an alkylene group) as one unit, and these units are continuously bonded. Here, the alkylene part constituting the alkylene oxide repeating unit is preferably a linear or branched alkylene group having 2 to 6 carbon atoms, more preferably an alkylene group having 2 to 4 carbon atoms, and 2 or 3 carbon atoms. An alkylene group is particularly preferred. (B-1) The ethylene group is most preferred from the viewpoint of the interaction with the carboxy group-containing polymerizable compound.
Further, two or more types of alkylene oxide repeating units having different alkylene part structures may be present in the same alkylene oxide chain, and the repeating pattern in that case may be random or block.

  Further, the number of repeating alkylene oxide repeating units is preferably about 2 to 100, and this number of repeating is an average value of the entire alkylene oxide-containing polymerizable compound to be used, and the actual value may have a distribution. The number of repeating alkylene oxide repeating units is more preferably an average of 4 or more in order to express the interaction with the component (B-1), and an average of 50 in order to suppress an increase in the viscosity of the ink composition. More preferably, it is more preferable, and it is especially preferable that it is 25 or less on average.

  (B-2) As an alkylene oxide containing polymeric compound, the compound shown by the following general formula (II) is mentioned as a preferable thing.

In the general formula (II), R ¹ represents a hydrogen atom or a methyl group, and is preferably a hydrogen atom from the viewpoints of reactivity and flexibility of the polymer produced by the polymerization reaction. X represents an oxygen atom or NR ′, and is preferably an oxygen atom because it improves the mobility around the polymerizable site. Here, R ′ represents a hydrogen atom or an alkyl group, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom. Z ¹ and Z ² each independently represent an ethylene group, a propylene group (linear or branched), or a butylene group (linear or branched). n is an integer of 1 to 80, and m is an integer of 0 to 80. When m is an integer of 1 or more, Z ¹ and Z ² are not the same. When m and n are 1 or more and m + n is 3 or more, the repeating pattern of (Z ¹ -O) and (Z ² -O) may be random or block. Z ¹ or Z ² is preferably an ethylene group. R ² is to display the hydrogen atom or an alkyl group having 1 to 18 carbon atoms. In addition, R ² is preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and most preferably an alkyl group, preferably a methyl group, for the inkjet suitability of the ink composition. One of the groups.

  Specific examples [(B-2-1) to (B-2-17)] of the alkylene oxide-containing polymerizable compound that can be suitably used in the present invention are shown below, but the present invention is not limited thereto. It is not something.

  The content of the (B-2) alkylene oxide-containing polymerizable compound in the ink composition of the present invention is based on the total mass of the ink composition from the viewpoint of the balance between curing speed and flexibility, and ink jet suitability of the ink composition. And the range of 3-30 mass% is preferable, and the range of 5-25 mass% is still more preferable.

In the present invention, each of the component (B-1) and the component (B-2) may be used alone or in combination of two or more.
Further, from the viewpoint of interaction expression, the component (B-1), the component (B-2), and the content ratio (mass ratio) in the ink composition of the present invention are (B-1) :( B -2) = 10: 90 to 95: 5 is preferred.
Hereinafter, the component (B-1) and the component (B-2) may be collectively referred to as the component (B).

[(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.

(A-1) Radical polymerization 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, and (d) organic. Peroxide, (e) thio compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester Compounds, (l) compounds having a carbon halogen bond, and (m) alkylamine compounds.
The radical polymerization initiator of the present invention may be used alone or in combination.

(A-2) Cationic polymerization initiator In the present invention, as described later, when a cationic polymerizable compound is used in combination, it is preferable to use a cationic polymerization initiator in combination.
As a preferable cationic polymerization initiator (photoacid generator) that can be used in the present invention, for example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (Organic Electronics Materials Research Group, “For Imaging”). “Organic materials”, Bunshin Publishing (1993), pages 187-192). Examples of the cationic polymerization initiator suitable for the present invention are listed below.

First, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium, etc. be able to. Secondly, sulfonated products that generate sulfonic acid can be mentioned. Thirdly, a halide that generates hydrogen halide can also be used. Fourthly, an iron allene complex can be mentioned.
Such cationic polymerization initiators may be used alone or in combination of two or more.

In the present invention, the (A) polymerization initiator is a polymerizable compound for the component (B) or when the component (B) and the other polymerizable compound (C) as an optional component are used in combination. It is suitable that the content is preferably 0.01 to 35% by mass, more preferably 0.1 to 30% by mass, and still more preferably 0.5 to 30% by mass.
In addition, (A) the polymerization initiator is 200: 1 to 1: 200 in a mass ratio of the polymerization initiator to the sensitizing dye with respect to the (E) sensitizing dye that can be used as required later. Preferably, it is contained in the range of 50: 1 to 1:50, more preferably 20: 1 to 1: 5.

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.

[(C) Other polymerizable compound]
The ink composition of the present invention preferably contains (C) another polymerizable compound in addition to the components (B-1) and (B-2). Examples of other polymerizable compounds that can be used in combination with the present invention include radical polymerizable compounds and / or cationic polymerizable compounds.
(C) Other polymerizable compounds may be appropriately selected and used in relation to the objective properties or the relationship with (A) the polymerization initiator.

(C-1) Radical polymerizable compound The radical polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and having at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. Any type may be used, including those having chemical forms such as monomers, oligomers, and polymers. 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 Methacryl derivatives such as tan trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and other derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate More specifically, Shinzo Yamashita, “Cross-linking agent handbook”, (1981 Taiseisha); Kato Kiyomi, “UV / EB curing handbook (raw material)” (1985, Polymer publication) ); Rad-Tech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC); Eiichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun) Commercially available products described in the above, or radically polymerizable or crosslinkable monomers known in the industry, Ligomers and polymers can be used.

  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. Photocurable polymeric compound materials used in the described photopolymerizable compositions are known and can also be applied to the ink compositions of the present invention.

(C-2) Cationic polymerizable compound A cationically polymerizable compound may be used in combination with the ink composition of the present invention, if necessary.
The cationically polymerizable compound 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 cationic polymerizations known as photocationically polymerizable monomers. Sex 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.

(C-3) Other preferred polymerizable compounds Other polymerizable compounds in the present invention include (meth) acrylic monomers or prepolymers, epoxy monomers or prepolymers, urethane monomers or prepolymers (meth). Acrylic acid esters (hereinafter referred to as acrylate compounds as appropriate) are preferred. 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, and the like.

  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.

  (C) Monomers listed as other polymerizable compounds have low sensitization even at low molecular weight, and have high reactivity, low viscosity, and excellent adhesion to a recording medium. .

In order to further improve the sensitivity, bleeding, and adhesion to the recording medium, it is preferable to use a monoacrylate and a polyfunctional acrylate monomer or polyfunctional acrylate oligomer having a molecular weight of 400 or more, preferably 500 or more.
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, the aforementioned component (B-1), and (B-2) The combination of one type selected from the above component and a polyfunctional acrylate monomer or 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 monoacrylates, stearyl acrylate, isoamyl acrylate, isomystil acrylate, and isostearyl acrylate have high sensitivity and low shrinkage to prevent curling, and are preferable in terms of prevention of bleeding, odor of printed matter, and cost reduction of irradiation apparatus. .
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 the present invention, when the acrylate compound is used as (C) the other polymerizable compound, the acrylate compound is 30% by mass or more based on the total mass of the other polymerizable compound (that is, the total amount of the component (C)). It is preferable that it is 40 mass% or more, and it is still more preferable that it is 50 mass% or more. Moreover, (C) all the other polymerizable compounds used together can also be made into the said acrylate compound.

<Content of polymerizable compound>
In the present invention, the layer content of the polymerizable compound, that is, the total amount of the component (B) and the added amount of the other polymerizable compound (C) that can be used together with the component (B) is the total amount of the ink composition of the present invention. It is 6-55 mass% with respect to mass, More preferably, it is 10-45 mass%.

  In the ink composition of the present invention, the component (B) has a total content of polymerizable compounds contained in the ink composition (that is, a total content of the component (B) and the component (C)). On the other hand, the content is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and particularly preferably 30% by mass or more.

  In the present invention, regarding the selection of the polymerization initiator and the polymerizable compound, a combination of a cationic polymerizable compound and a cationic polymerization initiator is used 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 a combination of a radical polymerizable compound and a radical polymerization initiator, a radical / cation hybrid type curable ink may be used in combination of these polymerizable compound and polymerization initiator.

[(D) Colorant]
When the ink composition of the present invention is used for forming an image part of a lithographic printing plate, it is not particularly necessary to form a colored image. However, in order to improve the visibility of the formed image part, or the ink composition is used. When a colored image is to be formed, (D) a colorant can be contained.

  The colorant that can be used in the present invention is not particularly limited, but (D-1) pigments and (D-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 or the ink composition for inkjet recording functions 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. It is preferred to select compounds that do not.

(D-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.

(D-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. Therefore, 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.

  Of 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;

  It is preferable that the colorant that can be used in the present invention is appropriately dispersed in the ink after being added to the ink composition of the present invention or the ink composition for inkjet recording. 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, it is preferable to add 1 to 50 parts by mass of these dispersant and dispersion aid with respect to 100 parts by mass of the colorant.

  In preparing the ink composition of the present invention, the colorant may be blended by adding directly with each component. However, in order to improve dispersibility, the solvent or the component (B) used in the present invention in advance or in combination as desired. (C) It can also mix | blend after adding to the dispersion medium like other polymeric compounds, and carrying out uniform dispersion | distribution or dissolution.

  In the present invention, in order to avoid the deterioration of the solvent resistance when the solvent remains in the cured image and the problem of VOC (Volatile Organic Compound) of the remaining solvent, the colorant contains the component (B). It is preferable to add and mix them in advance with any one of the polymerizable compounds containing or a mixture thereof. 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%.

[(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 (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, squalium) ), Coumarins (for example, 7-diethylamino-4-methylcoumarin), and the like.

  Examples of more preferable sensitizing dyes include compounds represented by the following formulas (III) to (VII).

(In Formula (III), 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 (IV), 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 (III).)

(In the formula (V), 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 (VI), A ³ and A ⁴ each independently represent —S— or —NR ⁶² — or —NR ⁶³ —, and R ⁶² and R ⁶³ each independently represents 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 (VII), 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 (III) to (VII) 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, an organic solvent or water can be used as the solvent. In particular, the organic solvent can be added in order to improve the adhesion to the recording medium (support such as paper). The addition of an organic solvent is effective because the VOC problem can be avoided.
The amount of the organic solvent is, for example, 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 can be suitably used as an ink for inkjet 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.
In the inkjet recording method of the present invention, the ink composition of the present invention is ejected onto a recording medium (support, recording material, etc.) for inkjet recording, and actinic radiation is applied to the ink composition ejected onto the recording medium. It is a method of forming an image by irradiating and curing the ink.

That is, the inkjet recording method of the present invention comprises (a) a step of ejecting the ink composition 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 component (C) and other polymerizable compounds used in combination with each other as desired 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>
It is possible to produce a lithographic printing plate by applying the ink composition of the present invention on a hydrophilic support and curing using the inkjet 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 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, the adhesion to the hydrophobic image, the hydrophilicity, the 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, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and sealing treatment with hot water are preferable. Each will be described below.

-Sealing treatment with 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 of the present invention onto a hydrophilic support First, the ink composition 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 irradiating the discharged ink composition with actinic radiation to cure the ink composition, thereby forming a hydrophobic image formed by curing the ink composition. On the surface of the hydrophilic support The ink composition ejected on 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 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)
-Carboxy group-containing polymerizable compound B-1-6: (B-1) component 12.0 parts-Alkylene oxide-containing polymerizable compound B-2-1 17.4 parts (n is an average of 9): (B-2 ) Ingredients • Actilane 421 22.0 parts (*: Akcros acrylate monomer: Component (C))
・ Photomer 2017 (UV diluent manufactured by ECchem) 20.0 parts ・ Solsperse 32000 (dispersant made by Noveon) 0.4 part ・ 3.6 parts Irgalite Blue GLVO (Pigment made by Ciba Specialty Chemicals: (D) component)
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 part ・ Rapi-Cure DVE-3 8.0 parts (vinyl ether manufactured by ISP Europe: component (C))
・ Lucirin TPO (BASF photoinitiator: (A) component) 8.5 parts ・ Benzophenone (photoinitiator: (A) component) 4.0 parts ・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals, Inc. Initiator: (A) component)
・ Byk 307 (defoamer manufactured by BYK Chemie) 0.05 parts

* Activane 421 is propoxylated neopentyl glycol diacrylate (bifunctional acrylate).

(Evaluation of ink)
The obtained cyan ink composition was printed on a polyvinyl chloride sheet and irradiated by passing it through an iron-doped ultraviolet lamp (power 120 W / cm) at a speed of 40 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 adhesiveness and flexibility with the recording medium were evaluated by a cross-hatch test (EN ISO 2409), and showed high adhesiveness with class 4B. Further, the flexibility was evaluated by the degree of cracks generated in the cured film after bending the sheet 10 times. This bending test is performed in a five-step evaluation with 5 points indicating a state in which no cracks occur, and 3 or more points are evaluated as having no practical problems. As a result, slight cracks that do not affect the printed image are obtained. It was only admitted that the generation of 4 was evaluated.
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)
Carboxy group-containing polymerizable compound B-1-6: 6.7 parts of component (B-1) 6.7 parts of alkylene oxide polymerizable compound B-2-1 (n is an average of 23): (B-2) Ingredients Actylane 421 38.0 parts (Acrycros acrylate monomer: Component (C))
・ Photomer 2017 (UV diluent made by EChem) 20.0 parts ・ Solsperse 32000 (dispersant made by Noveon) 0.4 part ・ 3.6 parts Cinquasia Magenta RT-355D (pigment made by Ciba Specialty Chemicals: (D) component)
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 part ・ Rapi-Cure DVE-3 8.0 parts (vinyl ether manufactured by ISP Europe: component (C))
・ Lucirin TPO (BASF photoinitiator: (A) component) 8.5 parts ・ Benzophenone (photoinitiator: (A) component) 4.0 parts ・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals, Inc. Initiator: (A) component)
・ Byk 307 (defoamer manufactured by BYK Chemie) 0.05 parts

  The obtained magenta ink was printed on a polyvinyl chloride sheet and irradiated by passing it through an iron-doped ultraviolet lamp (power 120 W / cm) at a speed of 40 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)
Carboxy group polymerizable compound B-1-6: (B-1) component 12.7 parts Alkylene oxide polymerizable compound B-2-10 16.7 parts (n is 4.5 on average): (B-2 ) Ingredients Actylane 421 30.0 parts (Acrycros acrylate monomer: Component (C))
・ Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts ・ Solsperse 32000 (dispersant manufactured by Noveon) 0.4 parts
-Genorad 16 (Stabilizer manufactured by Rahn) 0.05 parts-Lucirin TPO (Photoinitiator manufactured by BASF: component (A)) 8.5 parts-Benzophenone (photoinitiator: component (A)) 4.0 parts・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals photoinitiator: component (A))
・ 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 120 W / cm) at a speed of 40 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)
Carboxy group-containing polymerizable compound B-1-1: (B-1) component 9.4 parts Alkylene oxide polymerizable compound B-2-12 10.0 parts (n is an average of 6): (B-2) Ingredients • Actilane 421 36.0 parts (Acrycros acrylate monomer: Component (C))
-Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts-Solsperse 32000 (dispersant made by Noveon) 0.4 parts-2.6 parts Microlith Black C-K (Pigments manufactured by Ciba Specialty Chemicals: (D) component)
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 parts ・ Rapi-Cure DVE-3 5.0 parts (vinyl ether manufactured by ISP Europe: component (C))
・ Lucirin TPO (BASF photoinitiator: (A) component) 8.5 parts ・ Benzophenone (photoinitiator: (A) component) 4.0 parts ・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals, Inc. Initiator: (A) component)
・ 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 120 W / cm) at a speed of 40 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)
Carboxy group-containing polymerizable compound B-1-7: (B-1) component 10.7 parts Alkylene oxide polymerizable compound B-2-1 16.7 parts (n is an average of 9): (B-2) Ingredients • Actilane 422 46.0 parts (*: Akcros acrylate monomer: (C) component)
-Solsperse 32000 (Noveon dispersant) 0.4 part-Irgalite Blue GLVO 3.6 parts (Ciba Specialty Chemicals pigment: (D) component)
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 parts ・ Rapi-Cure DVE-2 6.0 parts (vinyl ether manufactured by ISP Europe: component (C))
・ Lucirin TPO (BASF photoinitiator: (A) component) 8.5 parts ・ Benzophenone (photoinitiator: (A) component) 4.0 parts ・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals, Inc. Initiator: (A) component)
・ Byk 307 (defoamer manufactured by BYK Chemie) 0.05 parts

* Activane 422 is dipropylene glycol diacrylate (bifunctional acrylate).

  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 120 W / cm) at a speed of 40 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 6)
The following components were stirred with a high-speed water-cooled stirrer to obtain a cyan UV inkjet ink.
(Cyan ink composition)
-Carboxyl group-containing polymerizable compound B-1-6: (B-1) component 10.0 parts-Alkylene oxide-containing polymerizable compound B-2-1 20.0 parts (n is an average of 3): (B-2 ) Ingredients · KAYARAD HDDA 2.6 parts (* Nippon Kayaku acrylate monomer: (C) component)
-Actilane 421 40.0 parts (Acrycros acrylate monomer: component (C))
・ Solsperse 32000 (Noveon dispersant) 0.4 part ・ Solsperse 5000 (Noveon dispersant) 0.05 part ・ Irgalite Blue GLVO 1.4 parts (Ciba Specialty Chemicals pigment: (D) component)
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 parts ・ Rapi-Cure DVE-3 5.0 parts (vinyl ether manufactured by ISP Europe: component (C))
・ Lucirin TPO (BASF Photoinitiator: Component (A)) 8.0 parts ・ Benzophenone (Photoinitiator: Component (A)) 2.0 parts ・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals, Inc. Initiator: (A) component)
・ Byk 307 (antifoam manufactured by BYK Chemie) 0.5 part

* KAYARAD HDDA is 1,6-hexanediol diacrylate (bifunctional acrylate).

  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 120 W / cm) at a speed of 40 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)
-Alkylene oxide-containing polymerizable compound B-2-1 29.4 parts (n is an average of 9): (B-2) component Actylane 421 22.0 parts (the acrylate monomer manufactured by Akcros: component (C))
・ Photomer 2017 (UV diluent manufactured by ECchem) 20.0 parts ・ Solsperse 32000 (dispersant made by Noveon) 0.4 part ・ 3.6 parts Irgalite Blue GLVO (Pigment made by Ciba Specialty Chemicals: (D) component)
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 part ・ Rapi-Cure DVE-3 8.0 parts (vinyl ether manufactured by ISP Europe: component (C))
・ Lucirin TPO (BASF photoinitiator: (A) component) 8.5 parts ・ Benzophenone (photoinitiator: (A) component) 4.0 parts ・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals, Inc. Initiator: (A) component)
・ 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 120 W / cm) at a speed of 40 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 2)
The following components were stirred with a high-speed water-cooled stirrer to obtain a cyan UV inkjet ink.
(Cyan ink composition)
-Actilane 421 51.4 parts (the acrylate monomer manufactured by Akcros Co., Ltd .: component (C))
・ Photomer 2017 (UV diluent manufactured by ECchem) 20.0 parts ・ Solsperse 32000 (dispersant made by Noveon) 0.4 part ・ 3.6 parts Irgalite Blue GLVO (Pigment made by Ciba Specialty Chemicals: (D) component)
・ Genorad 16 (stabilizer manufactured by Rahn) 0.05 part ・ Rapi-Cure DVE-3 8.0 parts (vinyl ether manufactured by ISP Europe: component (C))
・ Lucirin TPO (BASF photoinitiator: (A) component) 8.5 parts ・ Benzophenone (photoinitiator: (A) component) 4.0 parts ・ Irgacure 184 4.0 parts (Ciba Specialty Chemicals, Inc. Initiator: (A) component)
・ 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 120 W / cm) at a speed of 40 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.

* Bending test is a sensory evaluation with 5 points when no cracks occur.

As is apparent from Table 1, each of the ink compositions of Examples 1 to 6 was 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, the ink composition of Comparative Example 1 which does not contain the component (B-1) and contains the component (B-2) and the bifunctional acrylate as a polymerizable compound has insufficient curability. After irradiation, it was confirmed by palpation that adhesiveness remained.
Further, the ink composition of Comparative Example 2 which does not contain the component (B-1) and the component (B-2) and has a bifunctional acrylate as a main component showed good curability, but the flexibility of the cured film Since the adhesiveness is not insufficient, the cured film is markedly cracked by bending the sheet, which is a practically problematic level.

(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 1 on the aluminum support prepared above, and an image was formed and cured in the same manner as in Example 1.
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 1 was applied to a Heidel KOR-D machine, and dampened with ink [VALUES-G Beni for Sheetfed (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, 10,000 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 where there is no practical problem. I confirmed that there was.

Claims (7)

(A) a polymerization initiator;
(B-1) (meth) acrylic acid, and at least one compound selected from the group consisting of an ester or amide having one (meth) acrylate Royle group have a carboxyl group in the molecule,
And (B-2) have a alkylene oxide repeating units in the molecule an ester or amide having one (meth) acrylate Royle group,
An ink composition comprising:   The ink composition according to claim 1, wherein (B-2) is a compound represented by the following general formula (II).

  In general formula (II), R ¹ Represents a hydrogen atom or a methyl group, R ² Represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. X represents an oxygen atom or NR ′ (R ′ represents a hydrogen atom or an alkyl group). Z ¹ And Z ² Each independently represents an ethylene group, a propylene group, or a butylene group. n is an integer of 1 to 80, and m is an integer of 0 to 80.
  When m is an integer of 1 or more, Z ¹ And Z ² Are not the same. When m and n are 1 or more and m + n is 3 or more, (Z ¹ -O) and (Z ² The repeating pattern with -O) may be random or block. Furthermore, the ink composition according to claim 1 or claim 2 containing (D) a colorant. The ink composition according to any one of claims 1 to 3, which is for inkjet recording. (A) a step of discharging the ink composition according to any one of claims 1 to 4 onto a recording medium; and (b) irradiating the discharged ink composition with actinic radiation, Curing the ink composition;
An inkjet recording method comprising: (A) a step of discharging the ink composition according to any one of claims 1 to 4 onto a hydrophilic support; and (b) irradiating the discharged ink composition with actinic radiation. A step of forming a hydrophobic image formed by curing the ink composition on the hydrophilic support by curing the ink composition;
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 6 .