JP2007119723A - Ink composition, method for ink jet recording, method for production of lithographic printing plate and lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition that is cured with irradiation of radiation ray in high sensitivity to form an image of high quality and the cured product of the ink has sufficient flexibility, to provide the method for ink jet recording by using the same, and provide the lithographic printing plate that can form an image of high quality by using the ink composition and has excellent printability and to provide a method for the production thereof, and provide the resultant lithographic printing plate. <P>SOLUTION: The ink composition comprises a polymerization initiator, at least one selected from the group consisting of (meth)acrylic acid, and monofunctional (meth)acrylic esters or amides bearing basic group in the molecule. Further, a method for ink jet recording using the ink composition and a method for production of the lithographic printing plate and the lithographic printing plate produced by the production method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type and a melt type thermal transfer method, an ink jet method and the like. The electrophotographic system requires a process of forming an electrostatic latent image on a photosensitive drum by charging and exposure, and there is a problem that the system becomes complicated and consequently the manufacturing cost becomes expensive. In addition, although the thermal transfer system is inexpensive, there are problems such as high running costs and waste materials due to the use of ink ribbons.
On the other hand, the ink jet method is an inexpensive apparatus and ejects ink only to a required image portion to form an image directly on a recording medium. Therefore, the ink can be used efficiently and the running cost is low. Furthermore, there is little noise and it is excellent as an image recording method.

  Ink compositions that can be cured by irradiation with actinic radiation such as ultraviolet rays (radiation curable ink compositions), for example, ink compositions for inkjet 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's ketone, anthraquinone, acridine, phenazine, benzophenone, 2-ethylanthraquinone, and the like have been generally used as photopolymerization initiators (see, for example, 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. For this reason, 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 radiation of the exposure light source 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, the polyfunctional acrylate used for the purpose of improving the sensitivity has 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 the recording medium In this case, cracks, peeling and the like are likely to occur, and there is a problem in durability of the formed image.

Conventionally, when preparing a lithographic printing plate, a so-called PS plate having a structure in which a lipophilic photosensitive resin layer is provided on a hydrophilic support is used, and the photosensitive resin layer is exposed imagewise. In this method, 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 portion of a lithographic printing plate, the ink droplets ejected on the support are quickly cured without causing bleeding, and the strength of the cured image portion and the adhesion to the support are excellent. In addition, it is desired that the image portion follows the bending 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 et al., Chemical Reviews, Vol. 93, (1993), p. 435-448.

An object of the present invention is to provide an ink composition that 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 object of the present invention is to provide an ink jet recording method using the ink composition.
Another object of the present invention is to provide a lithographic printing plate obtained using an ink composition that can be cured with high sensitivity by irradiation with ultraviolet rays, and a method for producing the lithographic printing plate.

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 having 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 comprises a polymerization initiator and a monofunctional (meth) acrylic acid ester or amide having a basic group in the molecule (hereinafter referred to as “basic group-containing monofunctional (meth) acrylic”). And an acid derivative ”).
The ink composition of the present invention further includes at least one compound selected from the group consisting of (meth) acrylic acid and an ester or amide of a monofunctional (meth) acrylic acid having an acidic group in the molecule (hereinafter referred to as “a”). As appropriate, it may be referred to as “an acidic group-containing monofunctional (meth) acrylic acid derivative”).

  When forming a colored image with the ink composition of the present invention, it is preferable to further contain a colorant. In addition, the ink composition of the present invention can be cured with high sensitivity by radiation irradiation, and therefore is suitable for inkjet recording.

  The ink jet 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 to form an ink composition. And a step of curing.

The method for producing a lithographic printing plate of the present invention comprises: (a) a step of ejecting the ink composition of the present invention onto a hydrophilic support; and (b) irradiating the ejected ink composition with actinic radiation. And a step of curing the ink composition to form a hydrophobic image formed by curing the ink composition on the hydrophilic support.
The lithographic printing plate is produced by the lithographic printing plate production method of the present invention, and has a hydrophobic region (ink receiving region) formed by curing the ink composition of the present invention on a hydrophilic support. It is characterized by that.

Although the operation of the present invention is not clear, it is estimated as follows.
In the present invention, a basic group-containing monofunctional (meth) acrylic acid derivative is used as the polymerizable compound. Although this basic group-containing monofunctional (meth) acrylic acid derivative functions as a monofunctional polymerizable monomer, it has a basic group in the molecule, so that oxygen in the system is converted to the base. Since the functional group is trapped and the polymerization reaction is efficiently generated and progressed by reducing the inhibition of polymerization by oxygen, even if a large amount of polyfunctional polymerizable compound is not contained, the surface is not sticky by exposure. A cured film can be formed, and since the formed film is mainly composed of a polyfunctional monomer, it is considered to have excellent flexibility.
Therefore, in the present invention, due to these functions possessed by these monofunctional (meth) acrylic acid derivatives, a decrease in the curing rate, which is a problem when using a monofunctional monomer, is suppressed, and high radiation exposure results. It is thought that sensitive curing is possible.
By such an action, in the present invention, it is considered that both the suppression of the decrease in the curing rate and the flexibility of the film after curing can be achieved.
In addition, in the present invention, in addition to the basic group-containing monofunctional (meth) acrylic acid derivative, an acidic group-containing monofunctional (meth) acrylic acid derivative is added and allowed to coexist, so that between a plurality of adjacent monomers. Since an acid-base interaction can be formed, and both of these function as pseudo bifunctional monomers, the curing rate can be further improved. Even in this case, the bond formed by the acid-base interaction is not as strong as in the case of using an ordinary polyfunctional monomer linked by a covalent bond. It becomes more flexible than when a composition containing a large amount of monomer is used.

According to the present invention, an ink composition that can be cured with high sensitivity to irradiation with actinic radiation, can form a high-quality image, and the image obtained by curing the ink has sufficient flexibility, and An ink jet recording method using the ink composition can be provided.
Further, by using the ink composition of the present invention, a lithographic printing plate which can be cured with high sensitivity by irradiation with ultraviolet rays and has excellent flexibility in the formed image portion, and a method for producing the lithographic printing plate Can be provided.

[Ink composition]
The ink composition of the present invention will be described in detail.
The ink composition of the present invention comprises (1) a polymerization initiator and (2) a basic group-containing monofunctional (meth) acrylic acid derivative.
Furthermore, if desired, at least one compound selected from the group consisting of (3) (meth) acrylic acid and an ester or amide of monofunctional (meth) acrylic acid having an acidic group in the molecule may be included.
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.

(2) Basic group-containing monofunctional (meth) acrylic acid derivative Basic group-containing monofunctional (meth) acrylic acid derivative, that is, an ester or amide of monofunctional (meth) acrylic acid having a basic group in the molecule, Any compound having one (meth) acrylic acid ester or amide and one or more basic groups in the molecule can be used without any particular limitation.
The number of basic groups present in the molecule is preferably from 1 to 3, more preferably from the viewpoint of suppressing a decrease in the curing rate due to the acid-base interaction formed and improving the flexibility of the film after curing. Is 1 to 2, particularly preferably 1.

In the basic group-containing monofunctional (meth) acrylic acid derivative, the functional group that can be used as the basic group is a functional group having a basic nitrogen atom from the viewpoint of inhibition of polymerization inhibition by oxygen and availability. In view of the stability of the ink composition, an aliphatic amino group or an aromatic amino group is more preferable, and an aliphatic amino group is particularly preferable. Among these, an aspect in which an aliphatic amino group forms a ring structure is most preferable from the viewpoint of effects.
Further, even in consideration of the case to coexist with the acid group-containing monofunctional (meth) acrylic acid derivative which will be described later, those having a functional group pK _a can form an acid group and a salt having a dissociative proton of less than 11 From the viewpoint of being preferable, it can be said that a functional group having a basic nitrogen atom is preferable.
Preferred examples of the base-containing monofunctional (meth) acrylic acid derivative 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 the mobility around the polymerizable site can be improved. 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, Z represents a divalent organic group, and preferred divalent organic groups include the following.

<Preferred specific example of Z>
* — (CH ₂ ) _n — * [n represents an integer of 2 to 12. ]
_{* -CH 2 -CH 2 -O-CO} -Z '- *
[Z ′ represents a divalent organic group selected from the following. ]
* _-C 6 _H 4 - *
_{* -C 6 H 4 - (CH} 2) n - * [n represents an integer of 1 to 12. ]
* — (CH ₂ ) _n —C ₆ H ₄ — * [n represents an integer of 1 to 12. ]
* — (CH ₂ ) _n —O—C ₆ H ₄ — *

上記化学式中、＊は連結部位を表す。
これら２価の有機基のなかでも、エチレン基、プロピレン基等の炭素原子数２〜６のアルキレン基が特に好ましい。
Ｒ^１およびＲ^２は、各々独立に、炭素数１〜４のアルキル基を表す。Ｒ^１およびＲ^２は互いに結合して環構造を形成してもよい。Ｒ^１およびＲ^２は互いに結合して５員又は６員の環構造を形成することが好ましい。

In the above chemical formula, * represents a linking site.
Among these divalent organic groups, an alkylene group having 2 to 6 carbon atoms such as an ethylene group and a propylene group is particularly preferable.
R ¹ and R ² each independently represents an alkyl group having 1 to 4 carbon atoms. R ¹ and R ² may combine with each other to form a ring structure. R ¹ and R ² are preferably bonded to each other to form a 5-membered or 6-membered ring structure.

  Specific examples of monofunctional (meth) acrylic acid ester or amide having an amino group, which is a preferred embodiment of a (meth) acrylic acid derivative containing a basic group in the molecule, which can be suitably used in the present invention [Exemplary compound (B-1) to (B-11)] are shown below, but the present invention is not limited thereto.

  The content of the basic group-containing monofunctional (meth) acrylic acid derivative in the ink composition of the present invention is based on the mass of the entire ink composition from the viewpoint of the balance between the curing speed and flexibility and the inkjet suitability of the ink composition. On the other hand, the range of 3-40 mass% is preferable, and the range of 7-25 mass% is still more preferable.

(3) At least one compound selected from the group consisting of (meth) acrylic acid and esters or amides of monofunctional (meth) acrylic acid having an acidic group in the molecule. Can add a compound selected from (meth) acrylic acid and acid group-containing monofunctional (meth) acrylic acid derivatives. By using this compound in combination, the curing sensitivity can be further improved.
The acidic group-containing monofunctional (meth) acrylic acid derivative in the present invention is at least selected from the group consisting of (meth) acrylic acid and esters or amides of monofunctional (meth) acrylic acid having an acidic group in the molecule. It is a kind of compound. Among the monofunctional (meth) acrylic acid derivatives containing acidic groups, the monofunctional (meth) acrylic acid ester or amide having an acidic group in the molecule is one (meth) acrylic ester or amide and 1 in the molecule. Any compound having at least one acidic group can be used without particular limitation.
In addition, the number of acidic groups present in the molecule is preferably 1 to 3, from the viewpoint of suppressing the decrease in the curing rate due to the acid-base interaction formed and improving the flexibility of the film after curing. Preferably it is 1 to 2, particularly preferably 1.

In the monofunctional (meth) acrylic acid ester or amide having an acidic group in the molecule, functional groups which can be used as the acidic group is preferably used as long as it is a functional group which pK _a has a dissociable proton of less than 11 From the viewpoint of the interaction and availability with the basic group-containing monofunctional (meth) acrylic acid derivatives described later, a carboxy group, a sulfonic acid group, a phenolic hydroxyl group, a phosphoric acid group, a phosphonic acid group , An aminosulfonyl group, and an active imide group as described in JP-A-2005-107112 are preferable. From the viewpoint of liquid properties and curability of the ink composition and flexibility after curing, a carboxy group and a sulfonic acid Group and phosphoric acid group are more preferable, and a carboxyl group is particularly preferable as an acidic group.

  Preferred examples of the acidic group-containing monofunctional (meth) acrylic acid derivative include acrylic acid, methacrylic acid, and a compound represented by the following general formula (II).

  In general formula (II), 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 the mobility around the polymerizable site can be improved. 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.

<Preferred specific example of Z>
* — (CH ₂ ) _n — * [n represents an integer of 2 to 12. ]
_{* -CH 2 -CH 2 -O-CO} -Z '- *
[Z ′ represents a divalent organic group selected from the following. ]
* _-C 6 _H 4 - *
_{* -C 6 H 4 - (CH} 2) n - * [n represents an integer of 1 to 12. ]
* — (CH ₂ ) _n —C ₆ H ₄ — * [n represents an integer of 1 to 12. ]
* — (CH ₂ ) _n —O—C ₆ H ₄ — *

In the above chemical formula, * represents a linking site.
In the present invention, among the monofunctional (meth) acrylic acid ester or amide having a carboxy group, the compound represented by the general formula (I) is more preferable from the viewpoint of handleability such as odor.
Specific examples [Example compounds (A-1) to (A-15)] of monofunctional (meth) acrylic acid esters or amides having a carboxy group in the molecule, which can be suitably used in the present invention, are shown below. However, the present invention is not limited to these.

  Specific examples [Example compounds (A-16) to (A-22)] of monofunctional (meth) acrylic acid esters or amides having a sulfonic acid group in the molecule that can be suitably used in the present invention are shown below. Although shown, this invention is not limited to these.

  Specific examples [Example compounds (A-23) to (A-26)] of monofunctional (meth) acrylic acid esters or amides having a phosphate group in the molecule that can be suitably used in the present invention are shown below. Although shown, this invention is not limited to these.

In the case of using (3) at least one compound selected from the group consisting of (meth) acrylic acid and a monofunctional (meth) acrylic acid ester or amide having an acidic group in the molecule for the ink composition of the present invention. The content is preferably in the range of 2 to 35% by mass, and 5 to 20% by mass with respect to the total mass of the ink composition, from the viewpoints of the viscosity and curing rate of the ink composition and the adhesion and flexibility of the cured film. The range of is more preferable.
Further, in the ink composition of the present invention, at least one compound selected from the group consisting of (meth) acrylic acid and a monofunctional (meth) acrylic acid ester or amide having an acidic group in the molecule, and a basic group The content of the mixture with the monofunctional (meth) acrylic acid derivative (hereinafter referred to as “a mixture of specific monofunctional (meth) acrylic acid derivatives” as appropriate) depends on the balance between curing speed and flexibility and the ink composition. From the viewpoint of inkjet suitability, the range of 10 to 50% by mass is preferable with respect to the total mass of the ink composition, and the range of 12 to 40% by mass is more preferable.
In the ink composition of the present invention, in the case of containing at least one compound selected from the group consisting of (meth) acrylic acid and monofunctional (meth) acrylic acid ester or amide having an acidic group in the molecule, (2) The molar ratio of the basic group-containing monofunctional (meth) acrylic acid derivative is preferably 40:60 to 60:40, and more preferably 50:50. When the mixing ratio exceeds the range of 40:60 to 60:40 in terms of molar ratio, ink jet aptitude is deteriorated due to a significant increase in viscosity of the ink composition.

(1) 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 the radiation include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays.
When the polymerizable compound is cured by irradiation with an electron beam, it may be cured without using a polymerization initiator.
Known compounds can be used as the thermal polymerization initiator and the photopolymerization initiator.

(1-1) 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, (d) ) Organic peroxides, (e) thio compounds, (f) hexaarylbiimidazole compounds, (g) ketoxime ester compounds, (h) borate compounds, (i) azinium compounds, (j) metallocene compounds, (k) An active ester compound, (l) a compound having a carbon halogen bond, and (m) an alkylamine compound are exemplified.
As described above, the radical polymerization initiators may be used alone or in combination of two or more.

(1-2) 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 ⁻ and CF ₃ SO ₃ ⁻ salts of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium and phosphonium are listed. be able to. Secondly, sulfonated products that generate sulfonic acid can be mentioned. Thirdly, a halide that generates hydrogen halide can also be used. Fourthly, an iron allene complex can be mentioned.

  As described above, the cationic polymerization initiators may be used alone or in combination of two or more.

  (1) The polymerization initiator is composed of (2) 100 parts by weight of a monofunctional (meth) acrylic acid derivative having a basic group, or (3) a monofunctional (meth) acrylic acid derivative having an acidic group. When 100 parts by mass of the mixture with the component (2), or other polymerizable compound (4) [other than the component (2) and component (3) described later] is used as an optional component. Is preferably 0.01 to 35 parts by mass, more preferably 100 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds obtained by adding a specific monofunctional (meth) acrylic acid derivative mixture and other polymerizable compounds. It is appropriate to contain in the range of 0.1-30 parts by mass, more preferably 0.5-30 parts by mass.

  Further, in the present invention, (1) the polymerization initiator can be used as necessary described later. (6) The mass ratio of the polymerization initiator to the sensitizing dye is 200: 1 to 1 with respect to the sensitizing dye. : 200, preferably 50: 1 to 1:50, more preferably 20: 1 to 1: 5.

  In the ink composition of the present invention, in addition to the 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. These optional components are described below.

(4) Other polymerizable compounds In the ink composition of the present invention, (2) a basic group-containing monofunctional (meth) acrylic acid derivative, and (3) (meth) acrylic acid used in combination as an optional component In addition to at least one compound selected from the group consisting of monofunctional (meth) acrylic acid esters or amides having an acidic group in the molecule, it is preferable to include (4) another polymerizable compound.
That is, it has a 5-membered or 6-membered ring structure containing a nitrogen atom, which is the most preferable embodiment of the (2) basic group-containing monofunctional (meth) acrylic acid derivative which is an important constituent of the present invention ( ) Since the copolymer obtained by polymerizing the acrylic acid derivative has a relatively low glass transition temperature (Tg), it is appropriately selected from other polymerizable compounds that can form a polymer compound having a high glass transition temperature. By using in combination, the curability, stability, strength, and the like of the image portion obtained by curing the ink composition can be adjusted.
Examples of other polymerizable compounds that can be used in combination with the present invention include radically polymerizable compounds and cationically polymerizable compounds. Other polymerizable compounds may be appropriately selected and used in relation to the intended properties or the polymerization initiator.

(4-1) 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 are described in JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-134011 and the like. And a photocurable polymerizable compound used in the photopolymerizable composition. As the cationic polymerizable compound, for example, a polymerizable compound applied to a cationic polymerization type photocurable resin is known. For example, photocationic polymerization type light sensitized to a visible light wavelength region of 400 nm or more is used. Examples of the polymerizable compound applied to the curable resin include polymerizable compounds described in JP-A-6-43633 and JP-A-8-324137.

(4-2) Cationic polymerizable compound The ink composition of the present invention may be used in combination with a cationic polymerizable compound, 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 the ink composition of the present invention, these cationic polymerizable compounds may be used alone or in combination of two or more, but from the viewpoint of effectively suppressing shrinkage during ink curing. Is preferably a combination of at least one compound selected from oxetane compounds and epoxy compounds and a vinyl ether compound.

(4-3) Other preferred polymerizable compounds Other polymerizable compounds used in the present invention include (meth) acrylic monomers or prepolymers, epoxy monomers or prepolymers, urethane monomers or prepolymers ( A (meth) acrylic ester (hereinafter referred to as “acrylate compound” where appropriate) is preferably used. More preferably, they are the following compounds.

  That is, 2-ethylhexyl-diglycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxybutyl acrylate, hydroxypivalate neopentyl glycol diacrylate, 2-acryloyloxyethyl phthalate, methoxy-polyethylene glycol acrylate, Tetramethylol methane triacrylate, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, dimethylol tricyclodecane diacrylate, ethoxylated phenyl acrylate, 2-acryloyloxyethyl succinic acid, nonylphenol EO adduct acrylate, modified glycerin Triacrylate, bisphenol A diglycidyl ether acrylic acid adduct, modified bisphenol A diacrylate, phenoxy-poly Tylene glycol acrylate, 2-acryloyloxyethyl hexahydrophthalic 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.

  (4) 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 sensitivity, bleeding, and adhesion to the recording medium, it is preferable to use monoacrylate in combination with 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 combination of a monoacrylate selected from the above compound group and a polyfunctional acrylate monomer or polyfunctional acrylate oligomer is used. It is preferable because the film strength can be increased while the film is flexible to improve adhesion.
Furthermore, an aspect in which at least three kinds of polymerizable compounds of monofunctional, bifunctional, and trifunctional or higher polyfunctional monomers are used in combination further maintains sensitivity, bleeding, and adhesion to a recording medium. This is preferable from the viewpoint of further improvement.

As monoacrylates, stearyl acrylate, isoamyl acrylate, isomistyl acrylate, and isostearyl acrylate have high sensitivity and low shrinkage to prevent curling, while preventing bleeding, odor of printed matter, and cost reduction of irradiation equipment. preferable.
As the oligomer that can be used in combination with the monoacrylate, an epoxy acrylate oligomer and a urethane acrylate oligomer are particularly preferable.
In addition, methacrylate has better skin irritation than acrylate.
Among the above compounds, when alkoxy acrylate is used in an amount of less than 70% by mass 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 (4) another polymerizable compound, the acrylate compound is 10% by mass with respect to the total mass of the other polymerizable compound (that is, the total amount of the component (4)). Preferably, the content is 15% by mass or more, and more preferably 20% by mass or more. (2) a monofunctional (meth) acrylic acid derivative having a basic group, and a mixture obtained by adding (3) a monofunctional (meth) acrylic acid derivative having an acidic group to the component (2) (4) All other polymerizable compounds used in combination may be the acrylate compound.

<Addition amount of polymerizable compound>
In the ink composition of the present invention, the total content of polymerizable compounds, that is, (2) a basic group-containing monofunctional (meth) acrylic acid derivative, and (3) an acidic group-containing monofunctional The total content of the (meth) acrylic acid derivative and (4) other polymerizable compound is preferably 5 to 97% by mass, more preferably 30 to the mass of the entire ink composition of the present invention. 95% by mass.

  As for the selection of the polymerization initiator and the polymerizable compound, as a means for preventing a decrease in sensitivity due to the light-shielding effect of the colorant used in the ink composition, a combination of a cationic polymerizable compound and a cationic polymerization initiator, and a radical In addition to the combination of a polymerizable compound and a radical polymerization initiator, a radical / cation hybrid type curable ink using these polymerizable compound and polymerization initiator in combination may be used.

(5) Colorant When the ink composition of the present invention is used for forming an image portion of a lithographic printing plate, it is not essential to form a colored image, but the visibility of the formed image portion is improved. Alternatively, when an ink composition is used to form a colored image, (5) a colorant can be contained.

  The colorant that can be used in the present invention is not particularly limited, but (5-1) pigments and (5-2) 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.

(5-1) 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 the red or magenta pigment 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, and the like.
Examples of the blue or cyan pigment include Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17-1, 22, 27, 28, 29, 36. , 60, and the like.
Examples of the green pigment include Pigment Green 7, 26, 36, 50, and party.
Examples of the yellow pigment include Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, and 137. 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, and the like.
Examples of the black pigment include Pigment Black 7, 28, 26, and the like.
Examples of the white pigment include Pigment White 6, 18, 21, and the like.
These pigments can be appropriately selected and used according to the purpose.

(5-2) Oil-soluble dye The oil-soluble dye that can be used in the present invention is described below.
The oil-soluble dye that can be used in the present invention means a dye that is substantially insoluble in water. Specifically, the solubility in water at 25 ° C. (the mass of the dye that can be dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Accordingly, the oil-soluble dye means a so-called water-insoluble pigment or oil-soluble dye, and among these, an oil-soluble dye is preferable.

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

  Among the oil-soluble dyes that can be used in the present invention, any magenta dye can be used. For example, aryl or heteryl 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, xanthene dyes; quinone dyes such as naphthoquinone, anthraquinone, anthrapyridone; condensed polycyclic dyes such as dioxazine dyes, etc. Can be mentioned.

  Of 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 a chromophore (color-forming 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 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.
Particularly preferred among these are: Nubian 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 B2 (Manufactured by Co., Ltd.), Aizen Spiron 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.
Further, when an oil-soluble dye is used 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, these dispersant and dispersion aid are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the colorant.

  In preparing the ink composition of the present invention, the colorant may be added by adding directly with each component. However, in order to improve dispersibility, a solvent or a specific monofunctional (meth) acrylic acid derivative according to the present invention is used in advance. Alternatively, it may be added to a dispersion medium such as other polymerizable compound used in combination as desired, and uniformly dispersed or dissolved before blending.

  In the present invention, in order to avoid the problem of deterioration of solvent resistance when the solvent remains in the cured image and the problem of VOC (Volatile Organic Compound) of the remaining solvent, the colorant has a specific monofunctionality. It is preferable to add and mix in advance with any one of the polymerizable compounds containing the (meth) acrylic acid derivative 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.

  One or more colorants may be appropriately selected according to the intended use of the ink composition.

  In the ink composition of the present invention, when using a colorant such as a pigment that remains in a solid state, the average particle diameter of the colorant particles is preferably 0.005 to 0.5 μm, more preferably. It is preferable to set the colorant, the dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so as to be 0.01 to 0.45 μm, and 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, in consideration of the ink physical properties and colorability, generally, the content of the colorant is 1 with respect to the total mass of the ink composition. It is preferable that it is -10 mass%, and it is more preferable to contain 2-8 mass%.

(6) Sensitizing dye A sensitizing dye can be added to the ink composition of the present invention in order to promote decomposition of the polymerization initiator 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 used in the ink composition may be used, but it should be 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 range of 350 nm to 450 nm.
For example, polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanine (Eg, 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.

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

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

In formula (X), Ar ¹ and Ar ² each independently represent an aryl group and are linked via a bond with —L ³ —. Here, L ³ represents —O— or —S—. W is synonymous with that shown in Formula (IX).

In the formula (XI), A ² represents a sulfur atom or NR ⁵⁹ , L ⁴ represents a nonmetallic atomic group that forms a basic nucleus of a 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 represents a monovalent nonmetallic atomic group, and R ⁵⁹ represents an alkyl group or an aryl group. )

In formula (XII), A ³ and A ⁴ each independently represent —S—, —NR ⁶² —, or —NR ⁶³ —, and R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted alkyl group, Or a substituted or unsubstituted aryl group, and 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. , R ⁶⁰ and R ⁶¹ each independently represent a hydrogen atom or a monovalent non-metallic atomic group, and R ⁶⁰ and R ⁶¹ can be bonded to each other to form an aliphatic or aromatic ring.

In formula (XIII), R ⁶⁶ represents an aromatic ring or a hetero ring which may have a substituent, and A ⁵ represents an oxygen atom, a sulfur atom or ═NR ⁶⁷ . R ⁶⁴ , R ⁶⁵ and R ⁶⁷ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁶⁷ and R ⁶⁴ , and R ⁶⁵ and R ⁶⁷ each represent an aliphatic or aromatic ring. Can be combined to form.

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

(7) 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 co-sensitizers 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 such as thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, No. 56-75643, such as 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercapto. And naphthalene.

  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 (diethyl phosphite, etc.), Si-H described in JP-A-8-65779 , Ge—H compounds and the like.

(8) Other components Other components can be added to the ink composition of the present invention as necessary. 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 and the ink composition for ink jet recording are radiation curable ink compositions, it is preferable that no solvent is contained so that the ink composition can react quickly and be cured 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, 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, washes, etc. 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). Esters, copolymers of (meth) acrylic acid and C3-14 alicyclic alcohols, copolymers of (meth) acrylic acid and C6-14 aromatic alcohols), and polymerizability And low molecular weight tackifying resins having an unsaturated bond.

-Properties of ink composition-
As described above, the ink composition of the present invention needs to contain a polymerization initiator and a specific monofunctional (meth) acrylic acid derivative, and as other optional components, other polymerizable compounds, colorants, and the like. It contains.
These components are preferably 1 to 10% by mass, more preferably 2 to 8% by mass of the colorant based on the total mass of the ink composition, and an acidic group-containing monofunctional (meth) acrylic acid derivative or basic. The total polymerizable compound including the group-containing monofunctional (meth) acrylic acid derivative is preferably 5 to 97% by mass, more preferably 30 to 95% by mass. The amount of the polymerization initiator is preferably 0.01 to 35% by mass, more preferably 0.1 to 30% by mass, and more preferably 0.1 to 30% by mass, based on the total polymerizable compound including the specific monofunctional (meth) acrylic acid derivative. It is suitable to contain so that it may become 0.5-30 mass% preferably.

The ink composition of the present invention can be suitably used as an ink for inkjet recording. The preferred physical properties in the usage mode as the ink for inkjet recording will be described.
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 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 active radiation is applied to the ink composition ejected onto the recording medium. , And the ink is cured to form an image.

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 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 ink jet recording method of the present invention, an ink jet recording apparatus described in detail below can be used.

<Inkjet recording apparatus>
There is no restriction | limiting in particular as an inkjet recording device used for the 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 has a constant temperature for the ejected ink, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion. The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors at each piping site and perform heating control according to the ink flow rate and the environmental temperature. The temperature sensor can be provided 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 thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

Next, (b) the step of irradiating the discharged 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 the polymerization initiator contained in the ink composition of the present invention is decomposed by irradiation with actinic radiation to generate radicals, acids, bases and other starting species, and the function of the starting species causes a specific monofunctionality ( This is because the polymerization reaction of the (meth) acrylic acid derivative and other polymerizable compound used in combination as required occurs and is accelerated, and the ink composition is cured. At this time, if a sensitizing dye is present together with the polymerization initiator in the ink composition, the sensitizing dye in the system absorbs actinic radiation to be in an excited state and promotes decomposition of the polymerization initiator by contacting with the polymerization initiator. And achieve a more sensitive curing reaction.

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 further more preferable that it is 350-420 nm.
In the present invention, the polymerization initiating system has sufficient sensitivity even with low-power 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 .
The active radiation, the illumination intensity on the exposed surface is, for example, 10 to 2,000 mW / cm ^2, preferably, it is suitable to 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 photocurable 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.
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 a porous recording medium before the ink penetrates to a deep part where the light source does not reach, residual unreacted monomer can be suppressed, and as a result, odor can be reduced. .
Further, the curing may be completed by another light source that is not driven. WO99 / 54415 pamphlet discloses a method using an optical fiber or a method of irradiating a recording unit with UV light by applying a collimated light source to a mirror surface provided on the side surface of the head unit as an irradiation method. The curing method can also be applied to the 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 way, the ink composition of the present invention is cured with high sensitivity by irradiation with actinic radiation, and forms a hydrophobic image on the surface of the recording medium.

[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. The lithographic printing plate manufacturing method 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. Forming a hydrophobic image formed by curing the composition 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. .

  A lithographic printing plate exposes a so-called PS plate having a configuration in which a lipophilic photosensitive resin layer is provided on a hydrophilic support for an image, solubilizes or cures the exposed portion to form an image, It was manufactured by dissolving and removing the non-image area. By applying the ink jet recording method of the present invention, the ink composition is directly ejected on the surface of the support according to the digitized image information and cured to form a lipophilic ink receiving area (hydrophobic area). Thus, a lithographic printing plate can be easily produced.

<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.
When the material used as the support has hydrophilicity, it can be used as the support as it is, and when it does not have hydrophilicity, the surface thereof may be subjected to a hydrophilic treatment.
Examples of materials that can be used for the support include, for example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), and plastic film (eg, diacetic acid). Cellulose, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film laminated or vapor-deposited with the above metals Etc. 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 an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable. 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 from 0.1 to 0.6 mm, and more preferably from 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 is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

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

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions of anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, an electrolyte concentration of 1 to 80% by mass solution, a liquid temperature of 5 to 70 ° C., a current density of 5 to 60 A / dm ^2, voltage 1 to 100 V, it is preferably 10 seconds to 5 minutes electrolysis time. 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 planographic printing plate can be obtained, which is preferable.

  As a 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, but the adhesiveness with the upper layer, hydrophilicity, dirt resistance, etc. are further improved. Therefore, as necessary, the micropore enlargement treatment and sealing treatment of the anodized film described in JP-A-2001-253181 and JP-A-2001-322365, and an aqueous solution containing a hydrophilic compound It is possible to appropriately select and perform surface hydrophilization treatment that is immersed in the substrate. Of course, these enlargement processing and sealing processing are not limited to those described above, and any conventionally known method can be performed.

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

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

The concentration of the inorganic fluorine compound in the aqueous solution is preferably 0.01% by mass or more, 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. Of these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.
The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. 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 with water vapor)
Examples of the sealing treatment with water vapor include a method of bringing pressurized or normal pressure water vapor into contact with the anodized film continuously or discontinuously.
The temperature of the water vapor is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 105 ° C. or lower.
The water vapor pressure is preferably in a range (1.008 × 10 ^{5 to} 1.043 × 10 ⁵ Pa) from (atmospheric pressure−50 mmAq) to (atmospheric pressure + 300 mmAq).
Further, the time for which the water vapor is contacted is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, more preferably 20 seconds or shorter.

(Sealing treatment with hot water)
Examples of the sealing treatment with water vapor include a method in which an aluminum plate on which an anodized film is formed is immersed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, and more preferably 20 seconds or shorter.
Examples of the hydrophilization treatment used in the present invention include US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There is an alkali metal silicate method as described in the book. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with 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 the image recording layer, good printing durability and good stain resistance are obtained, which is preferable.

(A) Step of discharging the ink composition onto the hydrophilic support First, the ink composition of the present invention is discharged onto the surface of the hydrophilic support. At this time, the ink composition is preferably heated to 40 to 80 ° C., more preferably 25 to 50 ° C., and the viscosity of the ink composition is preferably lowered to 7 to 30 mPa · s, more preferably 7 to 25 mPa · s. It is preferable to discharge after a short time. In particular, it is preferable to use an ink composition having an ink viscosity of 35 to 500 mPa · s at 25 ° C. because a great 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 water-based inks that are usually used in ink jet recording inks. Viscosity fluctuation of the ink has a great influence on the change of the droplet size and the change of the droplet discharge speed, and consequently 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 temperature control range is set to ± 5 ° C. of the set temperature, preferably ± 2 ° C. of the set temperature, more preferably set temperature ± 1 ° C.

(B) A process of forming a hydrophobic image by irradiating the ejected ink composition with actinic radiation and curing the ink composition The ink composition ejected on the surface of the hydrophilic support It is cured by irradiation. The details of the curing mechanism are the same as those described in the ink jet recording method.
By adopting the ink jet recording method as described above, the dot diameter of the landed ink can be kept constant even on various lithographic printing plate supports having different surface wettability, and the image quality is improved. . In this way, the ink composition of the present invention is cured by irradiation with actinic radiation, and a hydrophobic image is formed on the surface of the hydrophilic support to obtain a lithographic printing plate.

Here, the actinic radiation source used for curing the ink or preferred irradiation conditions thereof are also the same as those described in the ink jet recording method.
The ink composition of the present invention is cured with high sensitivity by actinic radiation, and can form a hydrophobic region excellent in adhesion to the support and film quality, so that the obtained lithographic printing plate has high image quality. Excellent printing durability.
It goes without saying that the ink composition of the present invention is useful not only for forming the image portion of such a lithographic printing plate but also as a commonly used ink composition.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the form 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)
Specific monomer B-5 [component (2)] 12.5 parts Actylane 421 ^* (Akcros acrylate monomer)
[Component (4)] 30.0 parts Photomer 2017 (UV diluent made by EChem) 28.9 parts Solsperse 32000 (dispersant made by Noveon) 0.4 parts Irgalite Blue GLVO (Ciba Specialty)
Chemicals Pigment) [(5) Colorant] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 8.0 parts / Lucirin TPO (BASF Photoinitiator) [Component (1)] 8.5 parts / Benzophenone (Photoinitiator) [Component (1)] 4.0 parts / Irgacure 184 (Ciba Specialty)
Chemicals photoinitiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie defoamer) 0.05 parts

  Here, Actilane 421 is propoxylated neopentyl glycol diacrylate (bifunctional acrylate).

<Evaluation of ink>
The obtained cyan ink composition was printed on a sheet made of polyvinyl chloride, and at a speed of 40 m / min and 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was carried out by passing the ink at a speed of 2 to cure the ink and obtain a printed matter.
At this time, the following evaluation was performed.

-Sensitivity-
The exposure energy in curing was measured with a light quantity integrator (UV PowerMAP manufactured by EIT). As a result, the integrated exposure amount of UV rays on the sheet in the case of 40 m / min, a cumulative exposure dose 330 mJ / cm ^2, the case of 60 m / min, was accumulated exposure 220 mJ / cm ^2. Since it can harden | cure with this integrated exposure amount, it was confirmed that all have hardened | cured with high sensitivity.

-Curability-
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 disappeared completely at an integrated exposure amount of about 330 mJ / cm ² and was excellent in curability. In addition, at the integrated exposure amount of 220 mJ / cm ² , there were some cases where the surface was slightly sticky, but it was a level that had no practical problem, and it was confirmed that the curability was good even at low energy exposure. It was.

-Adhesiveness and flexibility-
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 where no cracks occur at all, and 3 or more points are evaluated as having no practical problems. As a result, no cracks are observed in the printed image. It was rated 5 points.
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)
Specific monomer B-1 [(2) component] 10.4 parts Actylane 421 (Akcros acrylate monomer)
[Component (4)] 36.0 parts Photomer 2017 (UV diluent made by EChem) 25.0 parts Solsperse 32000 (dispersant made by Noveon) 0.4 parts Cinquasia Magenta RT-355 D (Ciba
Specialty Chemicals Pigment) [Component (5)] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapid-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 8.0 parts / Lucirin TPO (BASF Photoinitiator) [Component (1)] 8.5 parts / Benzophenone (Photoinitiator) [Component (1)] 4.0 parts / Irgacure 184 (Ciba Specialty)
Chemicals photoinitiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie defoamer) 0.05 parts

<Evaluation of ink>
The produced magenta ink composition was printed on a sheet made of polyvinyl chloride, and under a light beam of an iron-doped ultraviolet lamp (output: 120 W / cm ² ) at a speed of 40 m / min and 60 m / min. Irradiation was performed by passing at a speed. 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)
Specific monomer B-6 [component (2)] 10.0 parts Actylene 421 (Akcros acrylate monomer)
[Component (4)] 45.4 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (Noveon dispersant) 0.4 parts Chromophthalal Yellow LA
Chemicals Pigment) [(5) Component] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 4.0 parts ・ Lucirin TPO (Photoinitiator manufactured by BASF) [Component (1)] 8.5 parts ・ Benzophenone (Photoinitiator) [Component (1)] 4.0 parts ・ Irgacure 184 (Ciba Specialty)
Chemicals photoinitiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie defoamer) 0.05 parts

<Evaluation of ink>
The produced yellow ink composition was printed on a sheet made of polyvinyl chloride, and the speed was 40 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ) and 60 m / min. Irradiation was performed by passing at a speed. 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)
Specific monomer B-10 [component (2)] 19.7 parts Actylane 421 (Akcros acrylate monomer)
[Component (4)] 35.7 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (Noveon dispersant) 0.4 parts Microlith Black CK (Ciba Specialty)
Chemicals Pigment) [(5) Component] 2.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 5.0 parts ・ Lucirin TPO (Photoinitiator manufactured by BASF) [Component (1)] 8.5 parts ・ Benzophenone (Photoinitiator) [Component (1)] 4.0 parts ・ Irgacure 184 (Ciba Specialty)
Chemicals photoinitiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie defoamer) 0.05 parts

<Evaluation of ink>
The produced black ink composition was printed on a sheet made of polyvinyl chloride, and the speed was 40 m / min and 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was carried out by passing through. 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)
-Specific monomer B-1: [(2) component] 8.5 parts-Specific monomer A-6: [(3) component] 12.9 parts-Actilane 421 (Akcros acrylate monomer)
[Component (4)] 30.0 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (dispersant made by Noveon) 0.4 parts Irgalite Blue GLVO (Ciba Specialty)
Chemicals Pigment) [(5) Component] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 8.0 parts / Lucirin TPO (BASF photopolymerization initiator) [component (1)] 8.5 parts / benzophenone (photopolymerization initiator) [component (1)] 4.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals photopolymerization initiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie antifoaming agent) 0.05 parts

The obtained cyan ink composition was printed on a sheet made of polyvinyl chloride, and at a speed of 40 m / min and 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was carried out by passing the ink at a speed of 2 to cure the ink and obtain a printed matter. The printed matter with this ink was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.
In Example 5, the flexibility evaluated by the degree of cracks generated in the cured film after bending the sheet 10 times only allowed the occurrence of slight cracks that do not affect the printed image. It was evaluated.

Example 6
The following components were stirred with a high-speed water-cooled stirrer to obtain a magenta UV inkjet ink.

(Magenta ink composition)
Specific monomer B-1 [component (2)] 5.4 parts Specific monomer A-10 [component (3)] 10.0 parts Actylane 421 (Akcros acrylate monomer)
[Component (4)] 36.0 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (dispersant manufactured by Noveon) 0.4 parts Cinquasia Magenta RT-355 D
(Ciba Specialty Chemicals pigments)
[Component (5)] 3.6 parts Genorad 16 (stabilizer manufactured by Rahn) 0.05 parts Rapi-Cure DVE-3 (vinyl ether manufactured by ISP Europe)
[Component (4)] 8.0 parts / Lucirin TPO (BASF photopolymerization initiator) [component (1)] 8.5 parts / benzophenone (photopolymerization initiator) [component (1)] 4.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals photoinitiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie defoamer) 0.05 parts

<Evaluation of ink>
The produced magenta ink composition was printed on a sheet made of polyvinyl chloride, and under a light beam of an iron-doped ultraviolet lamp (output: 120 W / cm ² ) at a speed of 40 m / min and 60 m / min. Irradiation was performed by passing at a speed. 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 7
The following components were stirred with a high-speed water-cooled stirrer to obtain a yellow UV inkjet ink.
(Yellow color ink composition)
Specific monomer B-4 [component (2)] 4.5 parts Specific monomer A-7 [component (3)] 5.5 parts Actylane 421 (Akcros acrylate monomer)
[Component (4)] 45.4 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (Noveon dispersant) 0.4 parts Chromophthalal Yellow LA
Chemicals Pigment) [(5) Component] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 4.0 parts / Lucirin TPO (BASF Photopolymerization Initiator) [Component (1)] 8.5 parts / Benzophenone (Photopolymerization Initiator) [Component (1)] 4.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals photopolymerization initiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie antifoaming agent) 0.05 parts

<Evaluation of ink>
The produced yellow ink was printed on a sheet made of polyvinyl chloride, and at a speed of 40 m / min and a speed of 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was performed by passing. 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 8
The following components were stirred with a high-speed water-cooled stirrer to obtain a black UV inkjet ink.

(Black ink composition)
Specific monomer B-1 [component (2)] 9.7 parts Specific monomer A-6 [component (3)] 14.7 parts Actilane 421 (Akcros acrylate monomer)
[Component (4)] 31.0 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (Noveon dispersant) 0.4 parts Microlith Black C-K (Ciba Specialty)
Chemicals Pigment) [(5) Component] 2.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 5.0 parts ・ Lucirin TPO (Photopolymerization initiator manufactured by BASF) [Component (1)] 8.5 parts ・ Benzophenone (Photopolymerization initiator) [Component (1)] 4.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals photopolymerization initiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie antifoaming agent) 0.05 parts

<Evaluation of ink>
The produced black ink is printed on a sheet made of polyvinyl chloride and passes at a speed of 40 m / min and a speed of 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was performed. 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 9
The following components were stirred with a high-speed water-cooled stirrer to obtain a cyan UV inkjet ink.

(Cyan ink composition)
Specific monomer B-6 [component (2)] 12.2 parts Specific monomer A-6 [component (3)] 14.2 parts Actylane 422 (Akcros acrylate monomer)
[Component (4)] 49.0 parts · Solsperse 32000 (Noveon's dispersant) 0.4 parts · Irgalite Blue GLVO (Ciba Specialty)
Chemicals Pigment) [component (5)] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-2 (ISP Europe Vinyl Ether)
[Component (4)] 6.0 parts / Lucirin TPO (Photopolymerization initiator manufactured by BASF) [Component (1)] 8.5 parts / Benzophenone (Photopolymerization initiator) [Component (1)] 4.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals photopolymerization initiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie antifoaming agent) 0.05 parts

  Here, Actilane 422 is dipropylene glycol diacrylate (bifunctional acrylate).

<Evaluation of ink>
The produced cyan ink was printed on a sheet made of polyvinyl chloride, and at a speed of 40 m / min and a speed of 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was performed by passing. 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 10
The following components were stirred with a high-speed water-cooled stirrer to obtain a cyan UV inkjet ink.

(Cyan ink composition)
・ Specific monomer B-1 [component (2)] 5.5 parts ・ Specific monomer A-22 [component (3)] 8.5 parts ・ KAYARAD HDDA (Nippon Kayaku acrylate monomer)
[Component (4)] 2.6 parts Actilane 421 (Akcros acrylate monomer)
[Component (4)] 66.0 parts Solsperse 32000 (Noveon dispersant) 0.4 parts Solsperse 5000 (Noveon dispersant) 0.05 parts Irgalite Blue GLVO (Ciba Specialty)
Chemicals Pigment) [(5) component] 1.4 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 5.0 parts · Lucirin TPO (BASF photopolymerization initiator) [component (1)] 8.0 parts · Benzophenone (photopolymerization initiator) [component (1)] 2.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals Photopolymerization Initiator) [Component (1)] 4.0 parts Byk 307 (BYK Chemie defoamer) 0.5 parts

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

<Evaluation of ink>
The produced cyan ink was printed on a sheet made of polyvinyl chloride, and at a speed of 40 m / min and a speed of 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was performed by passing. 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 comparative cyan UV inkjet ink.
(Comparative cyan ink composition)
・ Light acrylate HOA-MS [component (3)] 21.4 parts ・ Activane 421 (Akcros acrylate monomer)
[Component (4)] 30.0 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (dispersant made by Noveon) 0.4 parts Irgalite Blue GLVO (Ciba Specialty)
Chemicals Pigment) [(5) Component] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 8.0 parts / Lucirin TPO (BASF photopolymerization initiator) [component (1)] 8.5 parts / benzophenone (photopolymerization initiator) [component (1)] 4.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals photopolymerization initiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie antifoaming agent) 0.05 parts

  Here, light acrylate HOA-MS is 2-acryloyloxyethyl succinic acid (acid group-containing monofunctional acrylate) manufactured by Kyoeisha Chemical Co., Ltd.

<Evaluation of ink>
The produced cyan ink was printed on a sheet made of polyvinyl chloride, and at a speed of 40 m / min and a speed of 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was performed by passing. 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 (Akcros acrylate monomer)
[Component (4)] 51.4 parts Photomer 2017 (UV diluent manufactured by EChem) 20.0 parts Solsperse 32000 (Noveon dispersant) 0.4 parts Irgalite Blue GLVO (Ciba Specialty)
Chemicals Pigment) [(5) Component] 3.6 parts Genorad 16 (Rahn Stabilizer) 0.05 parts Rapi-Cure DVE-3 (ISP Europe Vinyl Ether)
[Component (4)] 8.0 parts / Lucirin TPO (BASF photopolymerization initiator) [component (1)] 8.5 parts / benzophenone (photopolymerization initiator) [component (1)] 4.0 parts・ Irgacure 184 (Ciba Specialty)
Chemicals photopolymerization initiator) [component (1)] 4.0 parts Byk 307 (BYK Chemie antifoaming agent) 0.05 parts

<Evaluation of ink>
The produced cyan ink was printed on a sheet made of polyvinyl chloride, and at a speed of 40 m / min and a speed of 60 m / min under the light of an iron-doped ultraviolet lamp (output: 120 W / cm ² ). Irradiation was performed by passing. The printed matter with this ink was evaluated in the same manner as in Example 1. The results are shown in Table 1 below.
In Table 1 below, the curing conditions (integrated exposure amount) of the ink composition in each test of “curability”, “adhesiveness”, and “flexibility” are also shown.

As is apparent from Table 1, the ink compositions of Examples 1 to 10 of the present invention are all cured with high sensitivity, the image portion is curable, the adhesiveness to the recording medium, and the image (film) is flexible. It was excellent in both sex.
On the other hand, a basic functional group-containing monofunctional (meth) acrylic acid derivative [component (2) in the present invention] is not included, and an acidic basic group-containing monofunctional (meth) acrylic acid derivative and a bifunctional acrylate are used as a polymerizable compound. The ink composition of Comparative Example 1 contained does not have sufficient curability, and contains an acidic group-containing monofunctional (meth) acrylic acid derivative and a basic group-containing monofunctional (meth) acrylic acid derivative as the polymerizable compound. The ink composition of Comparative Example 2 containing both bifunctional acrylates as a main component did not contain both, but exhibited good curability, but because the cured film was not sufficiently flexible and adhesive, the sheet was folded into a cured film. It was a level that caused significant cracks and became a practical problem.

Example 11
(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 using Al and an inevitable impurity aluminum alloy. After the molten metal treatment and filtration, an ingot having a thickness of 500 mm and a width of 1200 mm is obtained by DC casting 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 into 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 was drained 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) Alkaline etching treatment The aluminum plate was subjected to an 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 0.12 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.

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

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

(Preparation and evaluation of lithographic printing plates)
Printing was performed with the ink composition of Example 5 on the aluminum support prepared above, and an image was formed and cured in the same manner as in Example 1. This was used as a planographic printing plate to evaluate the image.

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. When the printed material after printing 100 sheets was visually evaluated, it was confirmed that the image had 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, it is possible to obtain 10,000 or more high-quality prints with no white spots in the image area and stains in the non-image area. It was confirmed that.

Claims (7)

  An ink composition comprising a polymerization initiator and a monofunctional (meth) acrylic acid ester or amide having a basic group in the molecule.   Furthermore, it contains at least 1 type of compound selected from the group which consists of ester or amide of (meth) acrylic acid and the monofunctional (meth) acrylic acid which has an acidic group in a molecule | numerator. Ink composition.   The ink composition according to claim 1 or 2, comprising a colorant.   The ink composition according to any one of claims 1 to 3, which is for inkjet recording. (A) a step of ejecting the ink composition according to any one of claims 1 to 4 onto a recording medium; and (b) irradiating the ejected ink composition with actinic radiation, Curing the ink composition;
An ink jet 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 process for producing a lithographic printing plate comprising:   A lithographic printing plate comprising a hydrophobic region obtained by applying and curing the ink composition according to any one of claims 1 to 4 on a hydrophilic support.