JP5591659B2 - Ink composition, ink set, and image forming method - Google Patents

Description

  The present invention relates to an ink composition suitable for recording an image by ejecting ink by an inkjet method, an ink set, and an image forming method using the same.

In recent years, paints and inks have become water-based due to increasing needs such as resource protection, environmental protection, and work stability improvement. As a means for improving the fixability of a printed image obtained with an aqueous ink, for example, an ultraviolet curable aqueous ink has been known for a long time.
As a water-soluble polymerizable compound applicable to such an ultraviolet curable aqueous ink, an ink containing a water-soluble photopolymerizable substance having a double bond and a coloring material, and a reaction accelerator composition were used. An image recording method is disclosed (for example, see Patent Document 1).

JP 2008-183820 A

However, in the image forming method described in Patent Document 1, there is room for further improvement in suppressing show-through (blocking resistance) that occurs when a plurality of sheets on which images are recorded are stacked.
Moreover, there is still room for improvement in reducing the color transfer to the tape that occurs when the tape is attached to the recorded image and peeled off (tape resistance).

  The present invention has been made in view of the above, and an object thereof is to provide an ink composition and an ink set excellent in blocking resistance and tape adhesion resistance, and an image forming method using the same.

Specific means for solving the above problems are as follows.
Item 1. (Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant,
(Component d) water, and (component e) hypophosphorous acid, formic acid, sulfurous acid, phosphorous acid or an ink composition containing these salts.

Item 2 . Item 2. The ink composition according to Item 1, comprising at least one polymerizable compound having two or more ethylenically unsaturated bonds as the (Component a).
Item 3 . Item 3. The ink composition according to Item 1 or 2 , wherein (Component a) has a polymerizable group selected from the group consisting of a (meth) acrylamide group, a maleimide group, a vinylsulfone group, and an N-vinylamide group.
Item 4 . Item 4. The ink composition according to any one of Items 1 to 3 , wherein the (Component a) has at least one (meth) acrylamide group.
Item 5 . The value (M _e / n _e ) obtained by dividing the molecular weight (M _e ) of the polymerizable compound having an ethylenically unsaturated bond by the content (n _e ) of the ethylenically unsaturated bond per molecule. Item 5. The ink composition according to any one of Items 1 to 4 , wherein is 175 or less.
Item 6 . The value (M _e / n _e ) obtained by dividing the molecular weight (M _e ) of the polymerizable compound having an ethylenically unsaturated bond by the content (n _e ) of the ethylenically unsaturated bond per molecule. Item 6. The ink composition according to any one of Items 1 to 5 , wherein is at least 84.
Item 7 . Item 7. The ink composition according to any one of Items 1 to 6 , wherein (Component c) is a pigment.
Item 8 . Item 8. The ink composition according to any one of Items 1 to 7 ,
An ink set comprising a treatment liquid containing an aggregating agent (component f) capable of forming an aggregate upon contact with the ink composition.
Item 9 . Item 9. The ink set according to Item 8 , wherein the treatment liquid further contains the (component e).
Item 10 . (Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant, and (Component d) Ink composition containing water;
(Component e) hypophosphorous acid, formic acid, sulfurous acid, phosphorous acid or a salt thereof, and a treatment liquid containing (component f) coagulant which can contact with the ink composition to form an aggregate Ink set.

Item 11 . Item 11. The ink set according to any one of Items 8 to 10 , wherein the treatment liquid contains at least one selected from an acidic compound, a polyvalent metal salt, and a cationic polymer.
Item 12 . A treatment liquid application step of applying the treatment liquid contained in the ink set according to any one of Items 8 to 11 onto a recording medium;
And an ink application step of applying an ink composition contained in the ink set onto a recording medium to form an image.
Item 13 . Item 13. The image forming method according to Item 12 , wherein the recording medium is coated paper.
Item 14 . Item 14. The image forming method according to Item 12 or 13 , wherein the ink application step is a step of applying the ink composition onto the recording medium to which the treatment liquid is applied in the treatment liquid application step.
Item 15 . Item 15. The image forming method according to any one of Items 12 to 14 , wherein the ink application step is a step of applying the ink composition by an inkjet method.

  According to the present invention, it is possible to provide an ink composition and an ink set excellent in blocking resistance and tape adhesion and an image forming method using the same.

  In the present invention, by using a compound represented by the following general formula (I) or a salt thereof, together with an ink composition containing a polymerizable compound having an ethylenically unsaturated bond, a photopolymerization initiator, a colorant and water, We succeeded in obtaining images with excellent blocking resistance and tape adhesion. These will be described below.

In general formula (I), A represents a phosphorus atom, a sulfur atom or a carbon atom. A is n ¹ For the phosphorus atoms represent 3, when n ¹ of A is a sulfur atom or a carbon atom represents 2. E represents a hydrogen atom or a hydroxyl group. However, a plurality of E may be the same or different, and at least one E represents a hydroxyl group.

  The compound represented by the general formula (I) or a salt thereof may be contained in the ink composition, and contains a flocculant that can form an aggregate upon contact with the ink composition. It may be contained in the ink composition or in both the ink composition and the treatment liquid.

The first aspect of the present invention is:
(Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant,
An ink composition containing (Component d) water, and (Component e) a compound represented by formula (I) or a salt thereof.

In general formula (I), A represents a phosphorus atom, a sulfur atom or a carbon atom. A is n ¹ For the phosphorus atoms represent 3, when n ¹ of A is a sulfur atom or a carbon atom represents 2. E represents a hydrogen atom or a hydroxyl group. However, a plurality of E may be the same or different, and at least one E represents a hydroxyl group.

The second aspect of the present invention is:
(Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant, and (Component d) Ink composition containing water;
(Component e) an ink set comprising: a compound represented by the general formula (I) or a salt thereof; and (Component f) a treatment liquid containing an aggregating agent capable of forming an aggregate upon contact with the ink composition. is there.

In general formula (I), A represents a phosphorus atom, a sulfur atom or a carbon atom. A is n ¹ For the phosphorus atoms represent 3, when n ¹ of A is a sulfur atom or a carbon atom represents 2. E represents a hydrogen atom or a hydroxyl group. However, a plurality of E may be the same or different, and at least one E represents a hydroxyl group.

  The first aspect will be described below.

≪First aspect≫
The first aspect of the present invention is:
(Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant,
(Component d) water, and
(Component e) An ink composition containing a compound represented by formula (I) or a salt thereof.

In general formula (I), A represents a phosphorus atom, a sulfur atom or a carbon atom. A is n ¹ For the phosphorus atoms represent 3, when n ¹ of A is a sulfur atom or a carbon atom represents 2. E represents a hydrogen atom or a hydroxyl group. However, a plurality of E may be the same or different, and at least one E represents a hydroxyl group.

<Ink composition>
The ink composition according to the first aspect of the present invention comprises (component a) a polymerizable compound having an ethylenically unsaturated bond, (component b) a photopolymerization initiator, (component c) a colorant, (component d) water, And (component e) contains a compound represented by the general formula (I) or a salt thereof, and further contains a water-soluble organic solvent and other additives as necessary.
The ink composition contains a compound represented by the general formula (I) or a salt thereof and a polymerizable compound having an ethylenically unsaturated bond. For example, after applying the ink composition onto a recording medium, active energy rays The effect of the present invention can be improved.

  The ink composition of the present invention is used not only for the formation of a single color image but also for the formation of a multicolor image (for example, a full color image), and an image can be formed by selecting one or more desired colors. When forming a multicolor image, the ink composition can be used as, for example, a magenta color ink, a cyan color ink, and a yellow color ink. Further, in order to adjust the color tone, it may be used as a black color tone ink.

In addition, the ink composition of the present invention is an ink having a color tone of red (R), green (G), blue (B), and white (W) other than the color tone of yellow (Y), magenta (M), and cyan (C). It can be used as a composition or an ink composition having a special color in the so-called printing field.
The ink composition of each color tone can be prepared by changing the hue of a colorant (for example, a pigment) as desired.

((Component e) Compound represented by Formula (I) or salt thereof)
The ink composition according to the first embodiment of the present invention contains a compound represented by the following general formula (I) or a salt thereof.

In general formula (I), A represents a phosphorus atom, a sulfur atom or a carbon atom. A is n ¹ For the phosphorus atoms represent 3, when n ¹ of A is a sulfur atom or a carbon atom represents 2. E represents a hydrogen atom or a hydroxyl group. However, a plurality of E may be the same or different, and at least one E represents a hydroxyl group.

  Specific examples of the compound represented by the general formula (I) include hypophosphorous acid, formic acid, sulfurous acid or phosphorous acid, and hypophosphorous acid or formic acid is preferable.

The salt of the compound represented by the general formula (I) may be any salt as long as it is a chemically acceptable salt. Examples of such salts include compounds represented by the general formula (I), inorganic bases (eg, alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium), and organic bases (eg, Organic amines such as ethanolamine, trimethylamine, triethylamine, t-butylamine, pyridine, picoline, diethanolamine, triethanolamine, dicyclohexylamine, N, N'-dibenzylethylenediamine, basic amino acids such as arginine, lysine, ornithine, etc. ), Salts with ammonia and the like.
The salt of the compound represented by the general formula (I) is preferably an alkali metal salt of the compound represented by the general formula (I), more preferably a sodium salt or a potassium salt, and most preferably a sodium salt.

  The content of the compound represented by the general formula (I) or a salt thereof in the ink composition in the first aspect of the present invention is preferably 0.5 to 10% by mass, and 1 to 5% by mass. % Is more preferable, and 1 to 3% by mass is most preferable.

((Component a) polymerizable compound having an ethylenically unsaturated bond)
The ink composition of the present invention contains at least one polymerizable compound having an ethylenically unsaturated bond. The polymerizable compound having an ethylenically unsaturated bond may be a water-insoluble compound or a water-soluble compound, but is preferably a polymerizable compound having a water-soluble ethylenically unsaturated bond. . In addition, water-soluble here means that the polymerizable compound having an ethylenically unsaturated bond is dissolved in distilled water at 25 ° C. at 2% by mass or more, preferably 5% by mass or more, It is more preferable to dissolve 10% by mass or more, still more preferable to dissolve 20% by mass or more, and particularly preferable to uniformly mix with water at an arbitrary ratio.

The polymerizable compound having an ethylenically unsaturated bond may be any compound as long as it is a compound having at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. Those having a form are included and are preferably monomers. The ink composition of the present invention preferably contains at least one compound having two or more ethylenically unsaturated bonds.
Only one type of polymerizable compound having an ethylenically unsaturated bond may be used, or two or more types may be used in combination at any ratio in order to improve the desired properties. It is preferable to use two or more kinds in combination for controlling performance such as reactivity and physical properties. Further, from the viewpoint of ink ejection stability, it is preferable to use a compound that has good solubility in water and hardly precipitates in the ink composition.

  Examples of polymerizable compounds having an ethylenically unsaturated bond include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and salts or derivatives thereof, ethylenically unsaturated groups Anhydrous anhydride, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and radically polymerizable compounds such as 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 Ritolol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, N, N-dimethylaminoacrylamide, N, N-dimethylaminoethylacrylamide, N, N-dimethylaminopropylacrylamide, and these Quaternized compounds, N-methylolacrylamide, hydroxyethylacrylamide, hydroxypropylacrylamide, 4-acryloylmorpholine, N- [1,1-dimethyl-2- (sodiooxysulfonyl) ethyl] acrylamide, diacetone acrylamide, epoxy acrylate Acrylic acid derivatives such as 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, trimethylolethane trimethacrylate , Trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, N, N-dimethylamino (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N- Methacrylic acid derivatives such as dimethylaminopropyl (meth) acrylamide,
In addition, derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, triallyl trimellitate and the like can be mentioned.

The polymerizable compound having an ethylenically unsaturated bond of the present invention preferably has a polymerizable group selected from the group consisting of a (meth) acrylamide group, a maleimide group, a vinylsulfonamide group, and an N-vinylamide group. Hereinafter, “(meth) acrylamide group, maleimide group, vinylsulfonamide group, and N-vinylamide group” may be collectively referred to as “amide group”. The (meth) acrylamide group means at least one of an acrylamide group and a methacrylamide group.
In the polymerizable compound having an ethylenically unsaturated bond, it is preferable that two or more “amide groups” exist. When two or more “amide groups” exist, the “amide groups” are the same. Or they may be different from each other.

  In the present invention, the polymerizable compound having an ethylenically unsaturated bond preferably has a polymerizable group selected from the group consisting of a (meth) acrylamide group, a maleimide group, and a vinylsulfonamide group. More preferably, it has a group.

  The (meth) acrylamide group is preferably the following structural formula (A1), the vinylsulfonamide group is preferably the following structural formula (A2), and the maleimide group is the following structural formula (A3). The N-vinylamide group is preferably the following structural formula (A4). Note that * in structural formulas (A1) to (A4) represents a bonding position.

In Structural Formula (A1), R ² represents a hydrogen atom or a methyl group. R ² is preferably a hydrogen atom.

In Structural Formula (A4), R ³ represents an alkyl group which may have a substituent or an aryl group which may have a substituent.
The alkyl group for R ³ is preferably an alkyl group having 1 to 3 carbon atoms. Specific examples of the alkyl group represented by R ³ include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. In the present invention, a methyl group or an ethyl group is preferable.
Moreover, as an aryl group in said R < ³ >, a C6-C10 aryl group is preferable. Specific examples of the aryl group represented by R ³ include a phenyl group and a naphthyl group. In the present invention, a phenyl group is preferable.

Examples of the substituent when the alkyl group represented by R ³ has a substituent include an alkoxy group, a halogen atom, a hydroxy group, and an amide group. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an ethylenedioxy group, and a methylenedioxy group. Furthermore, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the substituent when the aryl group represented by R ³ has a substituent include an alkyl group, an alkoxy group, a halogen atom, a hydroxy group, and an amide group. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and an alkylenedioxy group (for example, an ethylenedioxy group and a methylenedioxy group). Furthermore, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the present invention, R ³ in the structural formula (A4) is preferably a methyl group, an ethyl group, or a phenyl group, and more preferably a methyl group or an ethyl group.

A value obtained by dividing the molecular weight (M _e ) of the polymerizable compound having an ethylenically unsaturated bond by the number of ethylenically unsaturated bonds per molecule (n _e ) (M _e / n _e , hereinafter “A Value ”) is preferably 175 or less, and more preferably 165 or less from the viewpoint of blocking resistance and the like. The A value is preferably 84 or more from the viewpoint of structure.
Further, the A value is preferably 84 or more and 175 or less, and more preferably 84 or more and 165 or less.

The polymerizable compound having an ethylenically unsaturated bond preferably further has at least one hydrophilic group in addition to the polymerizable group. The hydrophilic group may be any of a nonionic group, an anionic group, and a cationic group, and may be betaine.
Specific examples of the hydrophilic group include oxyalkylene groups and oligomers thereof, hydroxyl groups, amide groups, sugar alcohol residues, urea groups, imino groups, amino groups, carboxyl groups, sulfonic acid groups, phosphoric acid groups, and thiol groups. A quaternary ammonium group etc. can be mentioned.

  In the present invention, the hydrophilic group is an oxyalkylene group and an oligomer thereof, a hydroxyl group, an amide group, a sugar alcohol residue, a urea group, an imino group, an amino group, a carboxyl group, a sulfonic acid group from the viewpoint of blocking resistance and the like. , A phosphoric acid group and a thiol group, more preferably at least one selected from an oxyalkylene group and an oligomer thereof and a hydroxyl group, an oxyethylene group, an oxypropylene group and an oligomer thereof (preferably Is more preferably at least one selected from n = 1 to 2) and a hydroxyl group.

  In the present invention, the polymerizable compound having an ethylenically unsaturated bond has a polymerizable group selected from the group consisting of a (meth) acrylamide group, a maleimide group, a vinylsulfonamide group, and an N-vinylamide group, The A value is preferably from 84 to 175, and has a polymerizable group selected from the group consisting of a (meth) acrylamide group, a maleimide group, a vinylsulfonamide group, and an N-vinylamide group, and the A value is More preferably, it is 84 or more and 165 or less, and it is a compound having a (meth) acrylamide group, and the A value is particularly preferably 84 or more and 165 or less.

  It is preferable that the aforementioned polymerizable compound having an ethylenically unsaturated bond further has a nonionic hydrophilic group, and has at least one nonionic hydrophilic group selected from an oxyalkylene group and an oligomer thereof and a hydroxyl group. More preferably, it has.

  Specific examples of the polymerizable compound having an ethylenically unsaturated bond that are preferably used in the present invention are shown below, but the present invention is not limited thereto.

  The content of the polymerizable compound having an ethylenically unsaturated bond in the ink composition of the present invention is preferably in the range of 1 to 50% by mass in terms of solid content, and preferably in the range of 1 to 40% by mass. More preferably, it is still more preferably in the range of 1 to 30% by mass.

  Furthermore, in the ink composition of the present invention, two or more polymerizable groups selected from the group consisting of a (meth) acrylamide group, a maleimide group, a vinylsulfonamide group, and an N-vinylamide group, a nonionic hydrophilic group, It is preferable that the polymerizable compound having an A value of 84 or more and 175 or less is contained in a range of 1 to 50% by mass in terms of solid content, (meth) acrylamide group, maleimide group, vinylsulfonamide group, And two or more polymerizable groups selected from the group consisting of N-vinylamide groups, and at least one nonionic hydrophilic group selected from oxyalkylene groups and oligomers thereof and hydroxyl groups, and the A value is It is more preferable that the polymerizable compound which is 84 or more and 165 or less is contained in the range of 1 to 40% by mass in terms of solid content, and more than 2 A polymerizable compound having a (meth) acrylamide group, at least one nonionic hydrophilic group selected from an oxyalkylene group and oligomer thereof, and a hydroxyl group, and having an A value of 84 to 165, in terms of solid content It is particularly preferable that the content be in the range of 1 to 30 mass%.

((Component b) Photopolymerization initiator)
The ink composition of the present invention contains at least one photopolymerization initiator. As the photopolymerization initiator, known photopolymerization initiators can be used without particular limitation.
Preferred photopolymerization 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) thios. Compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen bond And (m) an alkylamine compound.
Specific examples of the photopolymerization initiator include, for example, photopolymerization initiators described on pages 65 to 148 of “Ultraviolet curing system” written by Kiyosuke Kato (published by General Technology Center Co., Ltd .: 1989). Can be mentioned.
Specific examples of the photopolymerization initiator include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophene, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, p, p′-dichloro. Benzophene, p, p'-bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-propyl ether, benzoin isobutyl ether, benzoin n-butyl ether, benzyldimethyl ketal, tetra Methylthiuram monosulfide, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone (DETX), 2- Sopropylthioxanthone (ITX), azobisisobutyronitrile, benzoin peroxide, di-tert-butyl peroxide, 2,2-dimethoxy-1,2-diphenylethane-1-one (IRGACURE 651), 1-hydroxy Cyclohexyl phenyl ketone (IRGACURE184), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (IRGACURE2959), 2-hydroxy-2-methyl-1 -Phenylpropan-1-one (DAROCUR 1173), 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one (IRGACURE 127), 1- (4-Isopropyl) (Lopylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (IRGACURE 907), 2-benzyl-2-dimethylamino -1- (4-morpholinophenyl) -butanone-1 (IRGACURE 369), 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1 -Butanone (IRGACURE 379), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (DAROCUR TPO), bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (IRGACURE819), methylbenzoyl formate It is done. “IRGACURE” and “DAROCUR” are registered trademarks of BASF Japan. Furthermore, for example, aromatic diazonium salts, aromatic halonium salts, aromatic sulfonium salts, metallocene compounds such as triphenylsulfonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate and the like can be mentioned.

  As the photopolymerization initiator in the present invention, either a water-insoluble initiator dispersed in water or a water-soluble initiator can be used, but it should be a water-soluble photopolymerization initiator. preferable. In addition, the water solubility in a photoinitiator means melt | dissolving 0.5 mass% or more in distilled water at 25 degreeC. The water-soluble photopolymerization initiator is preferably dissolved in distilled water at 25 ° C. at 1% by mass or more, more preferably 3% by mass or more.

In this invention, a photoinitiator may be used individually by 1 type and may use 2 or more types together.
The content of the photopolymerization initiator in the ink composition of the present invention is preferably in the range of 0.1 to 30% by mass in terms of solid content, and more preferably in the range of 0.5 to 20% by mass. 1 to 15% by mass is more preferable.
In addition, the content of the photopolymerization initiator in the ink composition of the present invention is preferably 0.01 to 35 parts by mass, more preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the polymerizable compound. More preferably, it is contained in the range of 0.5 to 30 parts by mass.
Here, the content of the photopolymerization initiator means the total content of the photopolymerization initiator in the ink composition, and the content of the polymerizable compound means the polymerizable compound in the ink composition (ethylenic inert). It means the total content of a polymerizable compound having a saturated bond and other polymerizable compounds contained as necessary.

((Component c) Colorant)
The ink composition in the invention includes at least one colorant. As the colorant in the present invention, known dyes, pigments and the like can be used without particular limitation. Among these, from the viewpoint of ink colorability, a colorant that is almost insoluble or hardly soluble in water is preferable. Specific examples include various pigments, disperse dyes, oil-soluble dyes, dyes that form J aggregates, and more preferably pigments from the viewpoint of light resistance.

There is no restriction | limiting in particular as a pigment in this invention, A conventionally well-known organic and inorganic pigment can be used.
Examples of the organic pigment include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable. Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Examples of the dye chelates include basic dye chelates and acidic dye chelates.

  Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is particularly preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

  Specific examples of the pigment that can be used in the present invention include pigments described in paragraph numbers [0142] to [0145] of JP-A-2007-100071 shown below.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment Green 7 and siloxane-crosslinked aluminum phthalocyanine described in U.S. Pat. No. 4,311,775.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

Moreover, when using dye as a coloring agent in this invention, what hold | maintained dye at the water-insoluble support | carrier can be used. As the dye, known dyes can be used without particular limitation. For example, the dyes described in JP-A-2001-115066, JP-A-2001-335714, JP-A-2002-249677 and the like can be used in the present invention. It can be used suitably. The carrier is not particularly limited as long as it is insoluble in water or hardly soluble in water, and inorganic materials, organic materials, and composite materials thereof can be used. Specifically, the carriers described in JP-A-2001-181549, JP-A-2007-169418, etc. can be suitably used in the present invention.
The carrier holding the dye (colorant) can be used as it is or in combination with a dispersant as required. As the dispersant, a dispersant described later can be suitably used.

The above pigments may be used alone or in combination of a plurality of types selected from within each group or between groups.
The content of the colorant (particularly the pigment) in the ink composition is 1 to 25% by mass with respect to the total mass of the ink composition from the viewpoints of color density, graininess, ink stability, and ejection reliability. An amount of 1 to 20% by mass is more preferable.

(Dispersant)
When the colorant in the present invention is a pigment, it is preferable to form colored particles dispersed in an aqueous solvent by a dispersant. The dispersant may be a polymer dispersant or a low molecular surfactant type dispersant. The polymer dispersant may be either a water-soluble polymer dispersant or a water-insoluble polymer dispersant.
In the present invention, a water-insoluble polymer dispersant is preferable from the viewpoint of dispersion stability and dischargeability when applied to an ink jet system.

-Water-insoluble polymer dispersant-
The water-insoluble polymer dispersant in the present invention (hereinafter sometimes simply referred to as “dispersant”) is a water-insoluble polymer and is not particularly limited as long as the pigment can be dispersed. A dispersant can be used. The water-insoluble polymer dispersant can be constituted by including, for example, both a hydrophobic structural unit and a hydrophilic structural unit.

Examples of the monomer constituting the hydrophobic structural unit include styrene monomers, alkyl (meth) acrylates, aromatic group-containing (meth) acrylates, and the like.
Moreover, as a monomer which comprises the said hydrophilic structural unit, if it is a monomer containing a hydrophilic group, there will be no restriction | limiting in particular. Examples of the hydrophilic group include a nonionic group, a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Examples of the nonionic group include a hydroxyl group, an amide group (nitrogen atom is unsubstituted), a group derived from an alkylene oxide polymer (for example, polyethylene oxide, polypropylene oxide, etc.), a group derived from a sugar alcohol, and the like. .
From the viewpoint of dispersion stability, the hydrophilic structural unit in the present invention preferably contains at least a carboxyl group, and preferably includes a nonionic group and a carboxyl group.

Specific examples of the water-insoluble polymer dispersant in the present invention include a styrene- (meth) acrylic acid copolymer, a styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer, and a (meth) acrylic acid ester. -(Meth) acrylic acid copolymer, polyethylene glycol (meth) acrylate- (meth) acrylic acid copolymer, styrene-maleic acid copolymer and the like.
Here, “(meth) acrylic acid” means acrylic acid or methacrylic acid.

  In the present invention, the water-insoluble polymer dispersant is preferably a vinyl polymer containing a carboxyl group from the viewpoint of dispersion stability of the pigment, and a structural unit derived from at least an aromatic group-containing monomer as a hydrophobic structural unit. And a vinyl polymer having a structural unit containing a carboxyl group as a hydrophilic structural unit.

  The weight-average molecular weight of the water-insoluble polymer dispersant is preferably 3,000 to 200,000, more preferably 5,000 to 100,000, and still more preferably 5,000, from the viewpoint of pigment dispersion stability. -80,000, particularly preferably 10,000-60,000.

The content of the dispersant in the colored particles in the present invention is preferably 10 to 100% by mass of the dispersant with respect to the pigment from the viewpoint of the dispersibility of the pigment, the ink colorability, and the dispersion stability. The mass% is more preferable, and 30 to 50 mass% is particularly preferable.
When the content of the dispersing agent in the colored particles is in the above range, the pigment is preferably coated with an appropriate amount of the dispersing agent, and it tends to be easy to obtain colored particles having a small particle size and excellent stability over time.

  The colored particles in the present invention may contain other dispersants in addition to the water-insoluble polymer dispersant. For example, a conventionally known water-soluble low-molecular dispersant, water-soluble polymer, or the like can be used. The content of the dispersant other than the water-insoluble polymer dispersant can be used within the range of the content of the dispersant.

  The colorant in the present invention is preferably configured to contain the pigment and the water-insoluble polymer dispersant from the viewpoint of dispersion stability and dischargeability, and at least a part of the surface of the pigment is a water-insoluble polymer dispersant. It is preferable that it is configured to be coated with. Such a colorant can be obtained, for example, as a colored particle dispersion by dispersing a mixture containing a pigment, a dispersant, and, if necessary, a solvent (preferably an organic solvent) with a disperser.

  The colored particle dispersion is, for example, a step of adding an aqueous solution containing a basic substance to a mixture of the pigment, the water-insoluble polymer dispersant, and an organic solvent that dissolves or disperses the dispersant (mixing / hydration step). Then, the process (solvent removal process) except the said organic solvent can be provided, and it can manufacture as a dispersion. Thereby, the colorant is finely dispersed, and a dispersion of colored particles having excellent storage stability can be produced.

  The organic solvent needs to be able to dissolve or disperse the dispersant, but in addition to this, it is preferable that the organic solvent has a certain degree of affinity for water. Specifically, the solubility in water at 20 ° C. is preferably 10% by mass or more and 50% by mass or less.

More specifically, the colored particle dispersion can be produced by a production method including the following step (1) and step (2), but is not limited thereto.
Step (1): A step of dispersing a mixture containing a basic substance and a solution containing water as a main component together with a pigment, a dispersant, and an organic solvent in which the dispersant is dissolved or dispersed Step (2): Removing at least a portion of the organic solvent from the mixture after the dispersion treatment;

  In the step (1), first, the dispersant is dissolved or dispersed in an organic solvent to obtain a mixture (mixing step). Next, a solution containing a colorant and a basic substance and containing water as a main component, water, and, if necessary, a surfactant and the like are added to the mixture and mixed and dispersed to obtain an oil-in-water dispersion. Get.

  The basic substance is used for neutralization of an anionic group (preferably a carboxyl group) that the polymer may have. There is no particular limitation on the degree of neutralization of the anionic group. Usually, the liquid property of the finally obtained dispersion of colorant particles is preferably, for example, a pH of 4.5 to 10. The pH can also be determined by the desired degree of neutralization of the polymer.

  Preferable examples of the organic solvent include alcohol solvents, ketone solvents, and ether solvents. Among these, examples of alcohol solvents include ethanol, isopropanol, n-butanol, tertiary butanol, isobutanol, and diacetone alcohol. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Among these solvents, isopropanol, acetone and methyl ethyl ketone are preferable, and methyl ethyl ketone is particularly preferable. The organic solvent may be used alone or in combination.

In the production of the dispersion of the colored particles, a strong shearing force is applied using a two-roll, three-roll, ball mill, tron mill, disper, kneader, kneader, homogenizer, blender, single-screw or twin-screw extruder, etc. The kneading and dispersing treatment can be performed while feeding. Details of kneading and dispersion are described in “Paint Flow and Pigment Dispersion” by TC Patton (published by John Wiley and Sons, 1964).
If necessary, use a vertical or horizontal sand grinder, pin mill, slit mill, ultrasonic disperser, etc., and fine dispersion using beads made of glass having a particle diameter of 0.01 to 1 mm, zirconia, etc. It can be obtained by performing processing.

  The removal of the organic solvent in the method for producing the colored particle dispersion is not particularly limited, and can be removed by a known method such as vacuum distillation.

  The colored particles in the colored particle dispersion thus obtained maintain a good dispersion state, and the obtained colored particle dispersion has excellent temporal stability.

In the present invention, the volume average particle diameter of the colorant (or colored particles) is preferably 10 to 200 nm, more preferably 10 to 150 nm, and still more preferably 10 to 100 nm. When the volume average particle size is 200 nm or less, the color reproducibility is good, and in the case of the ink jet method, the droplet ejection characteristics are good. Moreover, light resistance becomes favorable because a volume average particle diameter is 10 nm or more.
Moreover, there is no restriction | limiting in particular regarding the particle size distribution of a coloring agent (or colored particle | grains), Any of a wide particle size distribution or a monodispersed particle size distribution may be sufficient. Further, two or more colorants having a monodispersed particle size distribution may be mixed and used.
The volume average particle size and particle size distribution of the colorant (or colored particles) can be measured using, for example, a light scattering method.
In the present invention, the colorant (or colored particles) may be used alone or in combination of two or more.

((Component d) Water)
The ink composition in the present invention contains water and is configured to contain at least one water-soluble organic solvent as required.
As water in this invention, it is preferable to use water which does not contain ionic impurities, such as ion-exchange water and distilled water. The water content in the ink composition is appropriately selected according to the purpose, but is usually preferably 10 to 95% by mass, more preferably 30 to 90% by mass.

(Water-soluble organic solvent)
The ink composition in the present invention can contain at least one water-soluble organic solvent. By containing the water-soluble organic solvent, the effect of preventing drying, wetting or promoting penetration can be obtained. In order to prevent drying, the ink adheres to and drys at the ink discharge port of the ejection nozzle and is used as an anti-drying agent to prevent clogging. For drying prevention and wetting, the vapor pressure is lower than that of water. A water-soluble organic solvent is preferred. In addition, the water-soluble organic solvent can be used as a penetration accelerator that enhances ink permeability to paper.

  Examples of water-soluble organic solvents include, for example, glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol and other alkanediols (polyhydric alcohols); sugar alcohols; ethanol, methanol, C1-C4 alkyl alcohols such as butanol, propanol, isopropanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono -N-propyl ether, ethylene glycol mono-isopropyl ether, diethylene glycol No-isopropyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monoethyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene Glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-isopropyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono N-propyl ether, dipropylene glycol mono-isopropyl ether , Glycol ethers such as tripropylene glycol monomethyl ether, and the like. These can be used individually by 1 type or in combination of 2 or more types.

  For the purpose of preventing drying and wetting, polyhydric alcohols are useful. For example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 2 , 3-butanediol and the like. These may be used individually by 1 type and may use 2 or more types together.

  For the purpose of promoting penetration, polyol compounds are preferred, and aliphatic diols are preferred. Examples of the aliphatic diol include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1,3-propanediol, -Ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol and the like. Among these, preferred examples include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.

In the present invention, the water-soluble organic solvent may be used alone or in combination of two or more.
Further, the content of the water-soluble organic solvent in the ink composition is preferably 1% by mass or more and 60% by mass or less, more preferably 1% by mass or more and 40% by mass or less.

(Resin particles)
The ink composition in the invention can contain at least one resin particle. By including the resin particles, it is possible to effectively improve the fixability of the ink composition to the recording medium, the abrasion resistance of the image, and the blocking resistance.
Also, the resin particles fix the ink composition, that is, the image by aggregating or destabilizing the ink to increase the viscosity of the ink when it comes into contact with the processing liquid described above or the area on the recording medium on which it has been dried. It is preferable to have a function to make it. Such resin particles are preferably dispersed in at least one of water and an organic solvent.

Examples of the resin particles that can be used in the present invention include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, styrene resins, crosslinked acrylic resins, Cross-linked styrene resins, benzoguanamine resins, phenol resins, silicone resins, epoxy resins, urethane resins, paraffin resins, fluorine resins, etc., or latex thereof can be used. Preferred examples include acrylic resins, acrylic-styrene resins, styrene resins, cross-linked acrylic resins, and cross-linked styrene resins.
The resin particles can also be used in the form of latex.

The weight average molecular weight of the resin particles is preferably 10,000 or more and 200,000 or less, more preferably 100,000 or more and 200,000 or less.
The volume average particle size of the resin particles is preferably in the range of 10 nm to 1 μm, more preferably in the range of 10 to 200 nm, still more preferably in the range of 20 to 100 nm, and particularly preferably in the range of 20 to 50 nm.
The glass transition temperature Tg of the resin particles is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 50 ° C. or higher.

The amount of resin particles added is preferably 0.1 to 20% by mass, more preferably 0.1 to 15% by mass, based on the ink.
Moreover, there is no restriction | limiting in particular regarding the particle size distribution of a resin microparticle, What has a wide particle size distribution or a thing with a monodispersed particle size distribution may be sufficient. Two or more kinds of resin particles having a monodispersed particle size distribution may be mixed and used.

(Surfactant)
The ink composition in the present invention can contain at least one surfactant as required. The surfactant can be used as a surface tension adjusting agent.
As the surface tension adjusting agent, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule or the like can be used effectively, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, Either a nonionic surfactant or a betaine surfactant can be used. Further, the above dispersant (polymer dispersant) may be used as a surfactant.
In the present invention, a nonionic surfactant is preferable from the viewpoint of suppression of ink droplet ejection interference, and an acetylene glycol derivative is more preferable.

When a surfactant (surface tension adjusting agent) is contained in the ink composition, the surfactant has a surface tension of 20 to 60 mN / m from the viewpoint of satisfactorily discharging the ink composition by an ink jet method. It is preferable to contain the quantity of the range which can be adjusted, More preferably, it is 20-45 mN / m from the point of surface tension, More preferably, it is 25-40 mN / m.
The specific amount of the surfactant in the ink composition of the surfactant is not particularly limited except that the range of the surface tension is preferable, and is preferably 1% by mass or more, more preferably 1 to 10% by mass. %, And more preferably 1 to 3% by mass.

(Other ingredients)
In addition to the above components, the ink composition may further contain various additives as other components as necessary.
Examples of the various additives include, for example, ultraviolet absorbers, antifading agents, antifungal agents, pH adjusters, rust inhibitors, antioxidants, emulsion stabilizers, preservatives, antifoaming agents, viscosity modifiers, and dispersions. Known additives such as stabilizers, chelating agents, solid wetting agents and the like can be mentioned.

  Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, nickel complex salt UV absorbers, and the like.

  As the anti-fading agent, various organic and metal complex anti-fading agents can be used. Examples of organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, and metal complexes. There are nickel complex, zinc complex and the like.

Examples of the antifungal agent include, for example, sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one, sodium sorbate, pentachlorophenol Sodium etc. are mentioned.
The antifungal agent preferably has a content in the ink composition of 0.02 to 1.00% by mass.

  The pH adjuster is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting the ink composition to be prepared, and can be appropriately selected according to the purpose. For example, alcohol amines (for example, diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol, etc.), alkali metal hydroxides (for example, lithium hydroxide, sodium hydroxide, potassium hydroxide) Etc.), ammonium hydroxide (for example, ammonium hydroxide, quaternary ammonium hydroxide, etc.), phosphonium hydroxide, alkali metal carbonate and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the antioxidant include phenol antioxidants (including hindered phenol antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like.

  Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate and the like.

(Physical properties of ink composition)
The surface tension (25 ° C.) of the ink composition in the invention is preferably from 20 mN / m to 60 mN / m. More preferably, it is 20 mN or more and 45 mN / m or less, More preferably, it is 25 mN / m or more and 40 mN / m or less.
The surface tension is measured under conditions of 25 ° C. using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

Further, the viscosity at 25 ° C. of the ink composition in the invention is preferably 1.2 mPa · s or more and 15.0 mPa · s or less, more preferably 2 mPa · s or more and less than 13 mPa · s, and further preferably. Is 2.5 mPa · s or more and less than 10 mPa · s.
The viscosity is measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD) under conditions of 25 ° C.

<Ink set>
The ink set of the present invention includes at least one of the ink compositions described above, and at least one treatment liquid containing a flocculant (component f) capable of forming an aggregate upon contact with the ink composition; including.
(Component a) a polymerizable compound having an ethylenically unsaturated bond, (Component b) a photopolymerization initiator, (Component c) a colorant, (Component d) water, and (Component e) represented by the general formula (I) By forming an image using an ink composition containing a compound or a salt thereof and a processing liquid containing (Component f) an aggregating agent, an image excellent in blocking resistance or the like is formed. In addition, the treatment liquid may contain a compound represented by the general formula (I) or a salt thereof (component e).

[Treatment solution]
The ink set of the present invention includes at least one flocculant capable of forming an aggregate upon contact with the ink composition, and includes other components as necessary.
When the processing liquid contains the (component f) flocculant, an image having excellent image quality and excellent blocking resistance can be formed.

((Component f) flocculant)
The treatment liquid in the present invention comprises an aggregating agent that aggregates the components in the ink composition. The flocculant in the present invention is capable of aggregating (fixing) the ink composition by contacting with the ink composition on the recording medium, and functions as a fixing agent. For example, when the treatment liquid is applied to a recording medium (preferably coated paper), the ink composition further drops and comes into contact with the aggregating agent in the state where the aggregating agent is present on the recording medium. The components in the ink composition are aggregated, and the components in the ink composition can be fixed on the recording medium.
Examples of the component for fixing the components in the ink composition include acidic compounds, polyvalent metal salts, and cationic polymers. These can be used alone or in combination of two or more.

-Acidic compounds-
Examples of acidic compounds include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, and tartaric acid. , Lactic acid, sulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, and derivatives of these compounds, etc. Preferably, these salts may be contained.

Among these, acidic compounds with high water solubility are preferable. Further, from the viewpoint of fixing the whole ink by reacting with the ink composition, an acidic compound having a valence of 3 or less is preferable, and an acidic compound having a valence of 2 to 3 is particularly preferable.
An acidic compound may be used individually by 1 type, and may use 2 or more types together.

  When the treatment liquid contains an acidic compound, the pH (25 ° C.) of the treatment liquid is preferably 0.1 to 6.8, more preferably 0.5 to 6.0, 0.8 More preferably, it is -5.0.

The content of the acidic compound is preferably 40% by mass or less, and more preferably 15 to 40% by mass with respect to the total mass of the treatment liquid. By setting the content of the acidic compound to 15 to 40% by mass, the components in the ink composition can be more efficiently fixed.
Furthermore, it is preferable that content of an acidic compound is 15 mass%-35 mass% with respect to the total mass of the said processing liquid, and it is more preferable that it is 20 mass%-30 mass%.

The amount of the acidic compound applied to the recording medium is not particularly limited as long as it is an amount sufficient to aggregate the ink composition, but 0.5 g / m ² to 4 from the viewpoint that the ink composition can be easily fixed. is preferably .0g / ^{m 2,} more preferably 0.9g / ^{m 2} ~3.75g / m 2

-Multivalent metal salt-
The polyvalent metal salt in the present invention is a compound containing a divalent or higher metal such as an alkaline earth metal and a zinc group metal, and includes acetates, oxides and the like of metal ions such as Ca ²⁺ , Cu ²⁺ , and Al ^3+. Can be mentioned.
In the present invention, the aggregation reaction of the ink composition when the ink composition is ejected onto a recording medium (preferably coated paper) to which the treatment liquid containing the polyvalent metal salt is applied is dispersed in the ink composition. This can be achieved by reducing the dispersion stability of the particles, for example, colorants typified by pigments and resin particles, and increasing the viscosity of the entire ink composition. For example, when particles such as pigments and resin particles in the ink composition have weakly acidic functional groups such as carboxyl groups, the particles are dispersed and stabilized by the action of the weakly acidic functional groups. Can be reduced by interacting with the polyvalent metal salt to lower the dispersion stability. Therefore, the polyvalent metal salt as the immobilizing agent contained in the treatment liquid needs to have a valence of 2 or more, that is, multivalent from the viewpoint of the aggregation reaction, and from the viewpoint of the aggregation reactivity, 3 A polyvalent metal salt composed of a polyvalent metal ion having a valence higher than that is preferable.

  From the above viewpoint, the polyvalent metal salt that can be used in the treatment liquid in the present invention is any one or more of the following salts of polyvalent metal ions and anions, polyaluminum hydroxide, and polyaluminum chloride. Preferably there is.

Examples of the polyvalent metal ions include Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Sr ²⁺ , Zn ²⁺ , Ba ²⁺ , Al ³⁺ , Fe ³⁺ , Cr ³⁺ , Co ³⁺ , Fe ²⁺ , La ³⁺ , Nd ³⁺ , Y ³⁺ , Zr ^{4+ and the} like. In order to contain these polyvalent metal ions in the treatment liquid, the polyvalent metal salt may be used.
The salt is a metal salt composed of the above polyvalent metal ions and an anion that binds to these ions, but is preferably soluble in a solvent. Here, the said solvent is a medium which comprises a process liquid with a polyvalent metal salt, for example, water and the organic solvent mentioned later are mentioned.

Preferred anions for forming a salt with the polyvalent metal ion include, for example, Cl ⁻ , NO ₃ ⁻ , I ⁻ , Br ⁻ , ClO ₃ ⁻ , CH ₃ COO ⁻ , SO ₄ ^{2− and the} like. .
A polyvalent metal ion and an anion can form a salt of a polyvalent metal ion and an anion, respectively, using a single species or a plurality of species.

  Examples of other polyvalent metal salts include polyaluminum hydroxide and polyaluminum chloride.

In the present invention, it is preferable to use a salt of a polyvalent metal ion and an anion from the viewpoints of reactivity, colorability, and ease of handling, and examples of the polyvalent metal ion include Ca ²⁺ and Mg ^2+. , Sr ²⁺ , Al ³⁺ and Y ³⁺ are preferable, and Ca ²⁺ is more preferable.
Further, as the anion, NO ₃ ⁻ is particularly preferable from the viewpoint of solubility and the like.
The said polyvalent metal salt can be used individually by 1 type or in mixture of 2 or more types.

Content of the said polyvalent metal salt is 15 mass% or more with respect to the total mass of the said process liquid. By setting the content of the polyvalent metal salt to 15% by mass or more, the components in the ink composition can be more effectively fixed.
The content of the polyvalent metal salt is preferably 15% by mass to 35% by mass and more preferably 20% by mass to 30% by mass with respect to the total mass of the treatment liquid.

The amount of the polyvalent metal salt applied to the recording medium is not particularly limited as long as it is an amount sufficient to aggregate the ink composition, but 0.5 g / m ² from the viewpoint that the ink composition can be easily fixed. it is preferably to 4.0 g / ^{m 2,} more preferably ^{0.9g / m 2 ~3.75g / m 2} .

-Cationic polymer-
The cationic polymer is at least one cationic polymer selected from poly (vinyl pyridine) salt, polyalkylaminoethyl acrylate, polyalkylaminoethyl methacrylate, poly (vinyl imidazole), polyethyleneimine, polybiguanide, and polyguanide. is there.
A cationic polymer may be used individually by 1 type, and may use 2 or more types together.
Among the cationic polymers, polyguanides (preferably poly (hexamethyleneguanidine) acetate, polymonoguanide, polymeric biguanide), polyethyleneimine, and poly (vinylpyridine), which are advantageous from the viewpoint of aggregation rate, are preferable.

  The weight average molecular weight of the cationic polymer is preferably smaller in terms of the viscosity of the treatment liquid. When the treatment liquid is applied to the recording medium by an inkjet method, a range of 500 to 500,000 is preferable, a range of 700 to 200,000 is more preferable, and a range of 1,000 to 100,000 is more preferable. . When the weight average molecular weight is 500 or more, it is advantageous from the viewpoint of aggregation speed, and when it is 500,000 or less, it is advantageous from the viewpoint of ejection reliability. However, this is not the case when the treatment liquid is applied to the recording medium by a method other than inkjet.

  When the treatment liquid contains a cationic polymer, the pH (25 ° C.) of the treatment liquid is preferably 1.0 to 10.0, more preferably 2.0 to 9.0, and 3. More preferably, it is 0-7.0.

The content of the cationic polymer is preferably 1% by mass to 35% by mass and more preferably 5% by mass to 25% by mass with respect to the total mass of the treatment liquid.
The amount of the cationic polymer applied to the coated paper is not particularly limited as long as it is an amount sufficient to stabilize the ink composition, but 0.5 g / m from the viewpoint that the ink composition is easily fixed. it is preferably ^{2 ~4.0g} / ^{m 2,} more preferably ^{0.9g / m 2 ~3.75g / m 2} .

≪Second aspect≫
The second aspect of the present invention is:
(Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant, and (Component d) Ink composition containing water;
(Component e) an ink set comprising: a compound represented by the general formula (I) or a salt thereof; and (Component f) a treatment liquid containing an aggregating agent capable of forming an aggregate upon contact with the ink composition. is there.

In general formula (I), A represents a phosphorus atom, a sulfur atom or a carbon atom. A is n ¹ For the phosphorus atoms represent 3, when n ¹ of A is a sulfur atom or a carbon atom represents 2. E represents a hydrogen atom or a hydroxyl group. However, a plurality of E may be the same or different, and at least one E represents a hydroxyl group.

  The polymerizable compound having an ethylenically unsaturated bond, the photopolymerization initiator, the colorant, water, and other additives in the second embodiment are the same as those described in the first embodiment, including the preferred range. is there.

The compound represented by the general formula (I) described in the first aspect, including the preferred range, of the compound represented by the general formula (I) or the salt thereof contained in the treatment liquid in the second aspect Or it is the same as its salt.
The content of the compound represented by the general formula (I) or a salt thereof with respect to the treatment liquid in the second aspect is preferably 0.5 to 20% by mass, and preferably 5 to 20% by mass. More preferably, it is most preferable that it is 3-15 mass%.

  The flocculant contained in the treatment liquid in the second aspect is the same as the flocculant described in the first aspect, including the preferred range.

  As described above, the mechanism by which the anti-blocking property and the like is improved by adopting the configuration of the first aspect or the second aspect of the present invention is not clear, but the present inventors infer as follows. That is, since the compound represented by the general formula (I) or a salt thereof has a functional group having a very high polarity, the compound represented by the general formula (I) or a salt thereof is incorporated into the image film by photocuring. Thus, it is considered that the affinity between the recording medium and the image portion is increased, and the blocking resistance and the tape adhesion resistance are improved. However, the above-mentioned mechanism is inference, and the present invention is not limited to this.

≪Image formation method≫
The image forming method of the present invention includes a treatment liquid application step for applying a treatment liquid contained in the ink set onto a recording medium, and an ink composition contained in the ink set on the recording medium to form an image. An ink application process to be formed, and further includes other processes as necessary.

<Processing liquid application process>
In the treatment liquid application step, the treatment liquid contained in the ink set is applied on the recording medium. For applying the treatment liquid to the recording medium, a known liquid application method can be used without particular limitation, and any method such as spray application, application by an application roller, application by an inkjet method, immersion, etc. can be selected. .

  Specifically, for example, a size press method represented by a horizontal size press method, a roll coater method, a calendar size press method, etc .; a knife coater method represented by an air knife coater method; a transfer roll such as a gate roll coater method Roll coater method represented by coater method, direct roll coater method, reverse roll coater method, squeeze roll coater method, etc .; bill blade coater method, short duel coater method; blade coater method represented by two stream coater method; rod Bar coater method represented by bar coater method, etc .; Bar coater method represented by rod bar coater method, etc .; Cast coater method; Gravure coater method; Curtain coater method; Die coater method; Brush coater method; Etc., and the like.

  Moreover, the method of apply | coating by controlling a coating amount by using the coating device provided with the liquid quantity limiting member like the coating device of Unexamined-Japanese-Patent No. 10-230201 may be used.

  The area to which the treatment liquid is applied may be the entire area application to the entire recording medium or the partial application to be partially applied to the area where ink jet recording is performed in the ink application process. In the present invention, the application amount of the treatment liquid is uniformly adjusted, and fine lines and fine image portions are uniformly recorded, and from the viewpoint of suppressing density unevenness such as image unevenness, coating is performed by application using an application roller or the like. It is preferable to apply the entire surface of the paper.

  Examples of the method of applying the treatment liquid by controlling the application amount of the treatment liquid within the above range include a method using an anilox roller. An anilox roller is a roller with a ceramic-sprayed roller surface processed with a laser to give it a pyramid shape, a diagonal line, a turtle shell shape, or the like. The treatment liquid enters the dent portion formed on the roller surface, is transferred when it comes into contact with the paper surface, and is applied in an application amount controlled by the dent of the anilox roller.

<Ink application process>
In the ink application process in the present invention, the ink composition contained in the ink set is applied onto a recording medium. The ink composition application method is not particularly limited as long as the ink composition can be applied in a desired image-like manner, and a known ink application method can be used. For example, a method of applying an ink composition onto a recording medium by means of an ink jet method, a copying method, a printing method, or the like can be given. Among these, the step of applying the ink composition by an ink jet method is preferable from the viewpoint of compactness of the recording apparatus and high-speed recording properties.

<Inkjet method>
In image formation by an ink jet method, by supplying energy, an ink composition is discharged onto a recording medium to form a colored image. As a preferable ink jet recording method for the present invention, the method described in paragraph Nos. 0093 to 0105 of JP-A No. 2003-306623 can be applied.

The inkjet method is not particularly limited, and is a known method, for example, a charge control method that discharges ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezoelectric element, Any of an acoustic ink jet method in which an electric signal is converted into an acoustic beam, irradiated onto ink, and ink is ejected using radiation pressure may be used.
The ink jet head used in the ink jet method may be an on-demand method or a continuous method. Furthermore, there are no particular limitations on the ink nozzles used when recording by the ink jet method, and they can be appropriately selected according to the purpose.
The ink jet method includes a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method using is included.

  Also, as an ink jet system, a short serial head is used, a shuttle system that performs recording while scanning the head in the width direction of the recording medium, and a line head in which recording elements are arranged corresponding to the entire area of one side of the recording medium There is a line system using. In the line method, an image can be recorded on the entire surface of the recording medium by scanning the recording medium in a direction orthogonal to the arrangement direction of the recording elements, and a carriage system such as a carriage for scanning a short head is not necessary. Further, since complicated scanning control of the carriage movement and the recording medium is not required, and only the recording medium is moved, the recording speed can be increased as compared with the shuttle system.

  In the present invention, the order in which the treatment liquid application step and the ink application step are performed is not particularly limited, but from the viewpoint of image quality, it is preferable that the ink application step is performed after the treatment liquid application step. That is, the ink application step is preferably a step of applying the ink composition onto the recording medium to which the treatment liquid has been applied.

<Active energy ray irradiation process>
The image forming method of the present invention preferably includes a step of irradiating the ink composition applied on the recording medium with active energy rays. By irradiating active energy rays, the polymerizable compound contained in the ink composition is polymerized to form a cured film containing a colorant. Thereby, the abrasion resistance and blocking resistance of the image are more effectively improved.

  The ink composition applied on the recording medium is cured by irradiation with active energy rays. This is because the initiator contained in the ink composition of the present invention is decomposed by irradiation with active energy rays to generate radicals, acids, bases and other starting species, and the polymerization reaction of the polymerizable compound is initiated by the starting species. This is because the ink composition is cured by being accelerated.

Here, α-rays, γ-rays, electron beams, X-rays, ultraviolet rays, visible light, infrared light, and the like are used as active energy rays. As a wavelength of an active energy ray, 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.
The output of the actinic energy ray is preferably at 5000 mJ / cm ² or less, more preferably 10~4000mJ / cm ^2, further preferably 20~3000mJ / cm ^2.

Mercury lamps and gas / solid lasers are mainly used as active energy ray sources, and mercury lamps and metal halide lamps are widely known as light sources used for curing UV photocurable ink jet recording inks. ing. 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 lifetime, high efficiency, and low cost, and are expected as light sources for photo-curable ink jets.
In addition, a light emitting diode (LED) and a laser diode (LD) can be used as an active energy ray 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.
A particularly preferable active energy ray source in the present invention is a UV-LED, and a UV-LED having a peak wavelength of 350 to 420 nm is particularly preferable.

<Ink drying process>
The image forming method of the present invention includes an ink drying step for drying and removing an ink solvent (for example, water, a water-soluble organic solvent, etc.) in the ink composition applied on the recording medium, if necessary. Also good. The ink drying step is not particularly limited as long as at least a part of the ink solvent can be removed, and a commonly used method can be applied.

  For example, the ink can be dried by a known heating means such as a heater, an air blowing means using air blowing such as a dryer, or a combination of these. As the heating method, for example, a method of applying heat with a heater or the like from the side opposite to the treatment liquid application surface of the recording medium, a method of applying warm air or hot air to the treatment liquid application surface of the recording medium, or an infrared heater was used. The heating method etc. are mentioned, You may heat combining these two or more.

  Moreover, the ink drying process should just be performed after an ink provision process, and may be before or after an active energy ray irradiation process. In this invention, it is preferable to carry out before an active energy ray irradiation process from a viewpoint of hardening sensitivity and blocking resistance.

<Recording medium>
The recording medium used in the image forming method of the present invention is not particularly limited, but general printing paper mainly composed of cellulose, such as so-called high-quality paper, coated paper, and art paper, used for general offset printing or the like is used. Can do. General printing paper mainly composed of cellulose is relatively slow in absorption and drying of ink in image recording by a general ink jet method using ink, and color material movement is likely to occur after droplet ejection, and image quality is likely to deteriorate. According to the image forming method of the present invention, it is possible to record a high quality image excellent in color density and hue while suppressing the movement of the color material.

  As the recording medium, commercially available media can be used. For example, “OK Prince fine quality” manufactured by Oji Paper Co., Ltd., “Shiorai” manufactured by Nippon Paper Industries Co., Ltd., and Nippon Paper Industries ( High-quality paper (A) such as “New NPI fine quality” manufactured by Nippon Paper Industries Co., Ltd., high-quality coated paper such as “Silver Diamond” manufactured by Nippon Paper Industries Co., Ltd., “OK Everlight Coat” manufactured by Oji Paper Co., Ltd. and Nippon Paper Industries Light coated paper (A3), such as “Aurora S” manufactured by Co., Ltd., “OK Coat L” manufactured by Oji Paper Co., Ltd., and “Aurora L” manufactured by Nippon Paper Industries Co., Ltd., Oji Coated paper (A2, B2) such as “OK Top Coat +” manufactured by Paper Industries Co., Ltd. and “Aurora Coat” manufactured by Nippon Paper Industries Co., Ltd. “OK Kanto +” manufactured by Oji Paper Co., Ltd. and Mitsubishi Paper Industries ( Art paper (A1) such as "Tokuhishi Art" and "Tokuhishi Art Both Sides N" manufactured by KK And the like. It is also possible to use various photographic papers for ink jet recording.

Among these, from the viewpoint of obtaining a high-quality image having a large color material movement suppression effect and better color density and hue than before, the water absorption coefficient Ka is preferably 0.05 to 0.5. a recording medium mL ^/ m 2 ^{· ms 1/2,} more preferably recording medium 0.1~0.4mL ^/ m 2 ^{· ms 1/2,} more preferably 0.2-0.3 ml / It is a recording medium of m ² · ms ^1/2 .

  The water absorption coefficient Ka is synonymous with that described in JAPAN TAPPI paper pulp test method No. 51: 2000 (issued by Japan Paper Pulp Technology Association). Specifically, the absorption coefficient Ka is an automatic scanning absorption meter. It is calculated from the difference in the amount of water transferred between the contact time of 100 ms and the contact time of 900 ms using KM500Win (manufactured by Kumagai Riki Co., Ltd.).

  Among the recording media, so-called coated paper used for general offset printing is preferable. The coated paper is obtained by applying a coating material to the surface of high-quality paper, neutral paper, or the like that is mainly surface-treated with cellulose as a main component and is not surface-treated. The coated paper is liable to cause quality problems such as glossiness and scratch resistance of the image in ordinary inkjet image formation. However, in the image forming method of the present invention, gloss unevenness is suppressed and glossiness and abrasion resistance are suppressed. An image with good properties can be obtained. In particular, it is preferable to use a coated paper having a base paper and a coat layer containing kaolin and / or calcium bicarbonate. More specifically, art paper, coated paper, lightweight coated paper, or finely coated paper is more preferable.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

(Synthesis of polymer dispersant P-1)
To a 1000 ml three-necked flask equipped with a stirrer and a condenser, 88 g of methyl ethyl ketone was added and heated to 72 ° C. in a nitrogen atmosphere. Then, a solution in which 10 g of methacrylic acid and 30 g of methyl methacrylate were dissolved was dropped over 3 hours. After completion of the dropwise addition, the reaction was further continued for 1 hour, and then a solution of 0.42 g of dimethyl 2,2′-azobisisobutyrate in 2 g of methyl ethyl ketone was added, heated to 78 ° C. and heated for 4 hours. The obtained reaction solution was reprecipitated twice in a large excess amount of hexane, and the precipitated resin was dried to obtain 96 g of a polymer dispersant P-1.
The composition of the obtained resin was confirmed by ¹ H-NMR, and the weight average molecular weight (Mw) determined by GPC was 44,600. Furthermore, when the acid value was calculated | required by the method as described in JIS specification (JISK0070: 1992), it was 65.2 mgKOH / g.

(Preparation of dispersion of resin-coated pigment)
-Resin-coated cyan pigment dispersion-

  The methyl ethyl ketone solution of the water-insoluble polymer dispersant P-1 obtained above in terms of solid content is 5.0 g, cyan pigment pigment blue 15: 3 (manufactured by Dainichi Seika Co., Ltd.) 10.0 g, methyl ethyl ketone 40.0 g, 8.0 g of 1 mol / L sodium hydroxide, 82.0 g of ion-exchanged water, and 300 g of 0.1 mm zirconia beads were supplied to the vessel and dispersed at 1000 rpm for 6 hours with a ready mill disperser (manufactured by IMEX Co., Ltd.). The obtained dispersion was concentrated under reduced pressure until the methyl ethyl ketone was sufficiently distilled off by an evaporator and the pigment concentration was 15%, and the cyan pigment dispersion B was used as a colorant comprising a pigment whose surface was coated with a water-insoluble polymer dispersant. -1 was obtained. The average particle diameter of the obtained cyan pigment dispersion was 77 nm.

(Synthesis of a polymerizable compound having an ethylenically unsaturated bond)
-Synthesis of polymerizable compound 2-
To a 1 L three-necked flask equipped with a stirrer was added 4,7,10-trioxa-1,13-tridecanediamine 40.0 g (182 mmol), sodium bicarbonate 37.8 g (450 mmol), water 100 g, tetrahydrofuran 300 mL, In an ice bath, 35.2 g (389 mmol) of acrylic acid chloride was added dropwise over 20 minutes. After dropping, the mixture was stirred at room temperature for 5 hours, and then tetrahydrofuran was distilled off from the obtained reaction mixture under reduced pressure. Next, the aqueous layer was extracted four times with 200 ml of ethyl acetate, and the obtained organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off under reduced pressure to obtain 35. 0 g (107 mmol, 59% yield) was obtained.

-Synthesis of polymerizable compound 4-
To a 1 L three-necked flask equipped with a stirrer was added 40.0 g (270 mmol) of 1,2-bis (2-aminoethoxy) ethane, 53.0 g (540 mmol) of maleic anhydride, and 200 mL of acetic acid. Stir with heating. The obtained reaction mixture was slowly poured into 500 mL of 6N aqueous potassium carbonate solution, sodium chloride was added, and the mixture was extracted 3 times with 600 mL of butanol. The obtained organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off under reduced pressure to obtain 41.6 g (135 mmol, yield 50%) of the target polymerizable compound 4.

-Synthesis of polymerizable compound 5-
To a 1 L three-necked flask equipped with a stirrer, 32.6 g (200 mmol) of 2-chloroethanesulfonyl chloride and 200 mL of methylene chloride were added, and 20.2 g (200 mmol) of triethylamine was added at −78 ° C., followed by stirring for 1 hour. Stir for 2 hours. To the reaction mixture, 14.8 g (100 mmol) of 1,2-bis (2-aminoethoxy) ethane and 20.2 g (200 mmol) of triethylamine were slowly added dropwise and stirred at room temperature for 3 hours under reduced pressure from the reaction mixture. Methylene chloride was distilled off. Next, 200 mL of 0.01 M aqueous hydrochloric acid solution was added, further added with sodium chloride, and extracted four times with 400 ml of ethyl acetate. The obtained organic layer was washed with aqueous sodium bicarbonate, dried over magnesium sulfate, filtered, and subjected to reduced pressure. By distilling off the solvent, 25.6 g (78 mmol, yield 78%) of the target polymerizable compound 5 was obtained.

-Synthesis of polymerizable compound 6-
To a 1 L three-necked flask equipped with a stirrer were added 40.0 g (270 mmol) of 1,2-bis (2-aminoethoxy) ethane, 26.2 g (594 mmol) of acetaldehyde, and 500 mL of tetrahydrofuran, and the mixture was stirred at room temperature for 5 hours. Thereafter, 50.9 g (648 mmol) of acetyl chloride and 70.8 g (700 mmol) of triethylamine were slowly added and stirred for 2 hours. To the reaction mixture was added 500 mL of sodium bicarbonate water, and the mixture was extracted 4 times with 800 ml of ethyl acetate. The obtained organic layer was washed with an aqueous ammonium chloride solution, dried over magnesium sulfate, filtered, and evaporated under reduced pressure. As a result, 30.7 g (108 mmol, yield 40%) of the target polymerizable compound 6 was obtained.

<Example 1>
Ink composition C-1 and treatment liquid D-1 were respectively prepared as follows, and ink set E-1 composed of these ink composition and treatment liquid was obtained.

(Preparation of ink composition C-1)
Using the dispersion of the resin-coated cyan pigment, each component was mixed so that the following ink composition C-1 was formulated, and then filtered through a 5 μm membrane filter to prepare an ink composition C-1. .

-Formulation of ink composition C-1-
-Resin-coated cyan pigment dispersion (component c) 26.6%
・ Irgacure 2959 (component b, source: BASF Japan)
... 3%
・ Polymerizable compound 2 (component a) 10%
・ Hydroxyethylacrylamide (component a, manufactured by Tokyo Chemical Industry Co., Ltd.)
... 10%
・ Olfin E1010 ・ ・ ・ 1%
(Nissin Chemical Co., Ltd .; surfactant)
・ Sodium hypophosphite (component e, source: Wako Pure Chemical) 2%
・ Ion-exchanged water (component d) ... added to be 100% as a whole.

(Preparation of treatment liquid D-1)
The following materials were mixed to prepare a treatment liquid D-1. It was 1.0 when pH (25 degreeC) of the processing liquid D-1 was measured with the Toa DKK Co., Ltd. product pH meter WM-50EG.

-Prescription of treatment liquid D-1-
Malonic acid (component f, manufactured by Tokyo Chemical Industry Co., Ltd.) 25.0%
・ Tripropylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.)
... 5.0%
・ Ion-exchanged water: Added to 100% overall.

<Examples 2 to 4>
In Example 1, instead of sodium hypophosphite, sodium phosphite (manufactured by Taihei Chemical Industry Co., Ltd.), sodium sulfite (manufactured by Wako Pure Chemical Industries, Ltd.) and sodium formate (manufactured by Kanto Chemical Co., Inc.) were used. Except for the above, ink compositions C-2 to C-4 were respectively prepared in the same manner as in Example 1.
Here, in the same manner that the ink set E-1 was constituted from the ink composition C-1 and the treatment liquid D-1, the ink compositions C-2 to C-4 and the treatment liquid D-1 were used. Ink sets E-2 to E-4 were prepared.

<Example 5>
Ink composition C-5 and treatment liquid D-2 were prepared as follows, and ink set E-5 composed of these ink composition and treatment liquid was obtained.

(Preparation of ink composition C-5)
Using the above resin-coated cyan pigment dispersion, each component was mixed so that the following composition of ink composition C-5 was obtained, and then filtered through a 5 μm membrane filter to prepare ink composition C-5. .

-Formulation of ink composition C-5-
-Resin-coated cyan pigment dispersion (component c) 26.6%
・ Irgacure 2959 (component b) 3%
Polymerizable compound 2 (component a) 10%
・ Hydroxyethylacrylamide (component a) 10%
・ Olfin E1010 ・ ・ ・ 1%
・ Ion-exchanged water (component d): Added to 100% as a whole.

(Preparation of treatment liquid D-2)
The following materials were mixed to prepare a treatment liquid D-2. It was 1.0 when the pH (25 degreeC) of the processing liquid 1 was measured with the pH meter WM-50EG by Toa DKK Co., Ltd.

-Prescription of treatment liquid D-2-
・ Malonic acid (component f) 25.0%
・ Sodium hypophosphite (component e): 10%
・ Tripropylene glycol monomethyl ether ... 5.0%
・ Ion-exchanged water: Added to 100% overall.

<Examples 6 to 8>
In the preparation of the treatment liquid D-2 of Example 5, treatment liquids D-3 to D were similarly performed except that sodium phosphite, sodium sulfite, and sodium formate were used instead of sodium hypophosphite, respectively. -5 were prepared respectively.
Here, using the ink composition C-5 and the treatment liquids D-3 to D-5 in the same manner as the ink set E-5 was composed of the ink composition C-5 and the treatment liquid D-2, Ink sets E-6 to E-8 were prepared.

<Examples 9 to 10>
Ink set E-9 was prepared in the same manner as in Example 1 except that the treatment liquid D-4 was used instead of the treatment liquid D-1. Ink set E-10 was prepared in the same manner as in Example 2 except that the treatment liquid D-5 was used instead of the treatment liquid D-1.

<Examples 11 to 13>
In the same manner as in the preparation of the ink composition C-1 of Example 1, except that the polymerizable compound 4, the polymerizable compound 5, and the polymerizable compound 6 were used instead of the polymerizable compound 2, respectively. C-6 to C-8 were respectively prepared.
Here, using the ink compositions C-6 to C-8 and the treatment liquid D-1 in the same manner that the ink set E-1 was constituted from the ink composition C-1 and the treatment liquid D-1, Ink sets E-11 to E-13 were prepared.

<Comparative Example 1>
Ink set EP-1 was prepared in the same manner as in Example 5 except that the treatment liquid D-1 was used instead of the treatment liquid D-2.

<Comparative example 2>
According to the method described in JP-A-2008-183820 (0072) to (0073), a cyan ink composition C-9 containing a photopolymerizable substance PA-1 and a photoinitiator TX-1, and a curing reaction accelerator N A treatment liquid D-6 containing -1 was prepared, and an ink set EP-2 was prepared using the ink composition C-9 and the treatment liquid D-6.

<Evaluation>
Each ink set prepared as described above was subjected to an image blocking resistance and tape adhesion resistance test as follows. The results are shown in Table 1.

(Blocking resistance)
The treatment liquid obtained above was applied onto Tokishi Art Double-sided N (manufactured by Mitsubishi Paper Industries Co., Ltd.) using a wire bar coater so as to have a film thickness of about 5 μm and dried.
The special diamond art both sides N to which the treatment liquid was applied were fixed on a stage operating at 500 mm / second. After that, the ink composition obtained above was refilled into a cartridge of GELJET GX5000 manufactured by Ricoh, and the resolution was 1200 × 600 dpi with a GELJET GX5000 printer head manufactured by Ricoh and fixed obliquely with respect to the scanning direction. A cyan solid image was printed by a line method with a drop amount of 3.5 pL.
Immediately after printing, it was dried at 60 ° C. for 3 seconds and further irradiated with ultraviolet rays at a dose of 400 mJ / cm ² using a high-pressure mercury lamp to cure the image area, thereby producing a print sample.

The print sample was cut into 3.5 cm × 4 cm and placed on a 10 cm × 10 cm acrylic plate. Ten sheets of unprinted Tokuhishi art double-sided N (manufactured by Mitsubishi Paper Industries) cut out to the same size were placed on the print sample, and a 10 cm × 10 cm acrylic plate was placed thereon. The sample was allowed to stand for 12 hours under the conditions of a temperature of 50 ° C. and a humidity of 60%, and then a 1 kg weight was placed on the acrylic plate and left for 24 hours (corresponding to a load of 700 kg / m ² ). After removing the weight and storing it for 2 hours under the conditions of a temperature of 25 ° C. and a humidity of 50%, the unprinted special diamond art was peeled off from the printed sample. The blocking resistance was evaluated according to the following evaluation criteria by resistance observed when peeling and visual observation of unprinted special diamond art.

-Evaluation criteria-
A ... It peeled off without resistance.
B: There was resistance when peeling, but there was no color transfer from the print sample.
C: There was resistance when peeling off, and the color transfer from the print sample could be confirmed, which was a level causing a problem in practical use.

(Tape resistance)
A print sample was produced in the same manner as the production of the print sample in the above-described blocking resistance evaluation method. Cellophane tape (manufactured by Nichiban Co., Ltd.) and mending tape (manufactured by 3M Co.) were each applied to the print sample so that the tape adhered to the entire surface, and then immediately peeled off. The color transfer to the peeled tape and the paper surface of the tape peeling part were observed, and the tape resistance was evaluated according to the following evaluation criteria.

―Evaluation criteria―
A: For both the cellophane tape and the mending tape, no color transfer was observed, and there was no image peeling on the paper surface.
B: A slight color transfer was observed on at least one of the cellophane tape or the mending tape, but image peeling on the paper surface was not visually recognized.
C: Color transfer was observed on at least one of the cellophane tape or the mending tape, and image peeling on the paper surface was also visually recognized.

Claims (15)

(Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant,
(Component d) water, and (component e) hypophosphorous acid, formic acid, sulfurous acid, phosphorous acid or an ink composition containing these salts. The ink composition according to claim 1, wherein the component (a) includes at least one polymerizable compound having two or more ethylenically unsaturated bonds. The ink composition according to claim 1, wherein the (component a) has a polymerizable group selected from the group consisting of a (meth) acrylamide group, a maleimide group, a vinylsulfone group, and an N-vinylamide group. object. Wherein (component a) has at least one (meth) acrylamide group, the ink composition according to any one of claims 1 to 3. The value (M _e / n _e ) obtained by dividing the molecular weight (M _e ) of the polymerizable compound having an ethylenically unsaturated bond by the content (n _e ) of the ethylenically unsaturated bond per molecule. The ink composition according to any one of claims 1 to 4 , wherein is 175 or less. The value (M _e / n _e ) obtained by dividing the molecular weight (M _e ) of the polymerizable compound having an ethylenically unsaturated bond by the content (n _e ) of the ethylenically unsaturated bond per molecule. the ink composition according to any one of claims 1 to 5 but is 84 or more. Wherein (component c) is a pigment, according to claim 1 the ink composition according to any one of claims 6. The ink composition according to any one of claims 1 to 7,
An ink set comprising a treatment liquid containing an aggregating agent (component f) capable of forming an aggregate upon contact with the ink composition. The ink set according to claim 8 , wherein the treatment liquid further contains the (component e). (Component a) a polymerizable compound having an ethylenically unsaturated bond,
(Component b) Photopolymerization initiator,
(Component c) Colorant, and (Component d) Ink composition containing water;
(Component e) hypophosphorous acid, formic acid, sulfurous acid, phosphorous acid or a salt thereof, and a treatment liquid containing (component f) coagulant which can contact with the ink composition to form an aggregate Ink set. The ink set according to any one of claims 8 to 10 , wherein the treatment liquid contains at least one selected from an acidic compound, a polyvalent metal salt, and a cationic polymer. A treatment liquid application step of applying the treatment liquid contained in the ink set according to any one of claims 8 to 11 onto a recording medium;
And an ink application step of applying an ink composition contained in the ink set onto a recording medium to form an image. The image forming method according to claim 12 , wherein the recording medium is coated paper. The image forming method according to claim 12 or 13 , wherein the ink application step is a step of applying the ink composition onto the recording medium to which the treatment liquid is applied in the treatment liquid application step. Said ink applying step is a step of applying the ink composition by an inkjet method, the image forming method according to any one of claims 12 to claim 14.