JP2011073195A - Ink set and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set that allows to form an image superior in rub resistance and offset resistance. <P>SOLUTION: The ink set contains an ink composition containing a coloring agent, and treatment liquid containing an acid generating agent and a flocculant. The ink composition further contains a water-soluble organic solvent and water. The acid generator generates an acid by at least either one of light and heat. The acid generator is at least one kind selected from an imido sulfonate, an oxime sulfonate, and a nitrobenzyl sulfonate. The flocculant is at least one kind selected from an acidic substance and a polyvalent metal salt. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink set and an image forming method.

  In recent years, various methods have been proposed as image forming methods for recording color images. In any case, there are high demands on the quality of recorded matter, such as image quality, texture, and curl after recording.

  For example, ink jet technology has been applied to the fields of office printers, home printers, and the like, but in recent years, it has been applied in the field of commercial printing. In the commercial printing field, there is a demand for a recorded material that does not have a photo-like surface but has a printing texture such as a printed material printed on general-purpose printing paper. In general, a recording medium dedicated for ink-jet recording has a thick solvent absorption layer of 20 to 30 μm, so that the surface gloss, texture, stiffness, etc. of the recording medium are limited, and it is possible to obtain a recorded matter having a texture of printed matter. It is difficult, and the cost is increased by having a solvent absorption layer and a water resistant layer. Therefore, the application of inkjet technology in the commercial printing field is limited to posters, form printing, and the like that are allowed to be limited in terms of surface gloss, texture, stiffness, etc., on the recording medium.

  On the other hand, as an inkjet recording method for forming a high-quality image, a liquid composition for improving the image is prepared separately from a normal inkjet ink, and this liquid composition is discharged prior to the ejection of the inkjet ink. Various methods for recording an image attached to a recording medium have been proposed (for example, see Patent Document 1). In these methods, the components in the ink are agglomerated on the surface of the paper by the fixing component of the ink jet ink, and are fixed before smearing or bleeding occurs.

  Also, from the viewpoint of accelerating the penetration of the ink solvent into the recording medium, the technology for incorporating a surfactant into the penetrating liquid for accelerating the penetration of the ink solvent into the recording medium and the performance such as the abrasion resistance of the image area are improved. In order to achieve this, a technique of applying an overcoat liquid to the image portion is also known (see, for example, Patent Document 2, Patent Document 3, and Patent Document 4).

JP 2004-59933 A JP 2004-174834 A JP 2005-271590 A Special table 2003-514999 gazette

However, in the techniques described in Patent Documents 1 to 4, in some cases, good image quality may not be obtained, and when fixing processing using a fixing roller is performed to improve the abrasion resistance of the image area. In some cases, an offset occurs in which the image portion on the recording medium is transferred to the fixing roller.
The present invention has been made in view of the above, and an object thereof is to provide an ink set and an image forming method capable of forming an image excellent in abrasion resistance and offset resistance.

Specific means for achieving the above object are as follows.
<1>
An ink set comprising: an ink composition containing a colorant; and a treatment liquid containing an acid generator and a flocculant.
<2>
The ink set according to <1>, wherein the ink composition further includes a water-soluble organic solvent and water.
<3>
The ink set according to <1> or <2>, wherein the acid generator generates an acid by at least one of light and heat.
<4>
The ink set according to any one of <1> to <3>, wherein the acid generator is at least one selected from imide sulfonate, oxime sulfonate, and nitrobenzyl sulfonate.
<5>
The ink set according to any one of <1> to <4>, wherein the flocculant is at least one selected from an acidic substance and a polyvalent metal salt.
<6>
<4> or <5>, wherein the acid generator is at least one selected from the following general formula (I), general formula (II), general formula (III), and general formula (IV): Ink set.

(In General Formula (I), C ₁ (carbon atom) and C ₂ (carbon atom) are bonded by a single bond or a double bond, and R ₁ or R ₂ may be the same or different, and the following (1 ) To any one of (4).
(1) A hydrogen atom, an alkyl group, a cycloalkyl group, and an aryl group each independently.
(2) A group that forms a monocyclic or polycyclic ring that may contain one or more heteroatoms together with C ₁ and C ₂ .
(3) A group forming a condensed aromatic ring containing C ₁ and C ₂ .
(4) A residue containing N-sulfonyloxyimide.
R ₃ represents an alkyl group, a halogenated alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or a camphor group.
In general formula (II), R ₄ and R _{5 each} have an optionally substituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group, cycloalkenyl group, or substituent group having 1 to 16 carbon atoms. Represents an aryl group, a heteroaryl group, or a cyano group. R ₄ and R ₅ are each independently an alkylene chain having 2 to 8 carbon atoms which may have a substituent, an alkenylene chain, an alkynylline chain, or phenylene which may have a substituent, It is bonded to R ₄ or R _{5 of} another compound represented by the general formula (II) via a linking chain containing freelen, thienylene, —O—, —S—, —N—, —CO—. Also good.
R ₆ represents an optionally substituted alkyl group having 1 to 16 carbon atoms, a cycloalkyl group, and an optionally substituted aryl group.
In general formula (III), Z represents an alkyl group, an aryl group, an alkylaryl group, a halogen-substituted alkyl group, a halogen-substituted aryl group, a halogen-substituted alkylaryl group, a nitro-substituted aryl group, nitro A substituted alkylaryl group, an aryl group having a nitro substituent and a halogen substituent, an alkylaryl group having a nitro substituent and a halogen substituent, or a formula —C ₆ H ₄ SO ₃ CHR′C ₆ H _4-m Represents a group having Q _m (NO ₂ ); R ′ represents a hydrogen atom, a methyl group, or a nitro-substituted aryl group. m represents 0, 1 or 2, and when m is 1 or 2, each Q independently represents a hydrocarbon group, a hydrocarbonoxy group, a nitro group, a halogen atom or an organosilicon group. However, Q is not an acidic group. R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an acyl group having 1 to 4 carbon atoms.
In general formula (IV), R ′ and R ″ may each independently have a linear or branched or cyclic alkyl group having 1 to 10 carbon atoms which may have a substituent, or may have a substituent. A good aryl group having 6 to 20 carbon atoms is shown.)
<7>
The ink set according to <5> or <6>, wherein the acidic substance is a trivalent or lower valent acidic substance.
<8>
The ink set according to any one of <5> to <7>, wherein the concentration of the acidic substance is 40% by mass or less based on the total mass of the treatment liquid.
<9>
The ink set according to any one of <5> to <7>, wherein the polyvalent metal salt is at least one polyvalent metal salt selected from a divalent metal salt and a trivalent metal salt.
<10>
The ink set according to any one of <1> to <9>, wherein the ink composition further includes resin particles.
<11>
Using the ink set according to any one of <1> to <10> above, a treatment liquid application step for applying a treatment liquid onto a recording medium, and an ink application step for applying an ink composition onto the recording medium. An image forming method comprising:
<12>
The image forming method according to <11>, wherein the recording medium is coated paper.
<13>
The image forming method according to <11> or <12>, wherein a treatment liquid is applied on a recording medium by the treatment liquid application step, and then an ink composition is applied by the ink application step.
<14>
The image forming method according to any one of <11> to <13>, wherein the ink application step forms an image by ejecting the ink composition by an inkjet method.

  According to the present invention, it is possible to provide an ink set and an image forming method capable of forming an image excellent in abrasion resistance and offset resistance.

<Ink set>
The ink set of the present invention includes at least one ink composition containing a colorant, and at least one treatment liquid containing an acid generator and a flocculant.
In the ink set of the present invention, since the treatment liquid contains both the acid generator and the flocculant, the formation speed of aggregates due to the contact between the treatment liquid and the ink composition is further improved, and the image quality is good. In addition, the abrasion resistance and offset resistance of the image are improved.
The ink set of the present invention is used for an inkjet image forming method, but can also be used for general writing instruments, recorders, pen plotters, and the like.

[Treatment solution]
The treatment liquid in the present invention contains at least one acid generator that generates an acid for aggregating the components in the ink composition and at least one aggregating agent for aggregating the components in the ink composition.

(Acid generator)
The acid generator is not particularly limited as long as it is a compound that generates an acid. Among them, a compound that generates an acid by at least one of light (light irradiation) and heat from the viewpoint of efficient acid generation. Preferably there is.
The acid generator can be used alone or in combination of two or more. In order to adjust the sensitivity, a sensitizer and the like can be used in combination with the acid generator.

(A1) Photoacid generator The photoacid generator is used as a photoinitiator for photocationic polymerization, a photoinitiator for photoradical polymerization, a photodecolorant for dyes, a photochromic agent, or a microresist. Known compounds that generate an acid upon irradiation with actinic rays or radiation (light irradiation) and mixtures thereof, quinonediazide compounds, dihydropyridine compounds, and the like can be appropriately selected and used.

  Examples include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and nitrobenzyl sulfonates. The preferred photoacid generator is at least one selected from imide sulfonate, oxime sulfonate, and nitrobenzyl sulfonate, which are compounds that generate sulfonic acid. By containing these photoacid generators, it is possible to efficiently generate an acid that aggregates the components in the ink composition, and the quality of the image in which the components in the ink composition are aggregated and fixed is improved. In addition, the scratch resistance and offset resistance of the image are improved.

  Further, a group that generates an acid upon irradiation with actinic rays or radiation, or a compound in which a compound is introduced into the main chain or side chain of the resin, such as US Pat. No. 3,849,137, German Patent No. 3914407, JP-A 63-26653, JP-A 55-164824, JP-A 62-69263, JP-A 63-146038, JP-A 63-163452, JP-A 62-153853, JP-A The compounds described in 63-146029 and the like can be used.

  Further, compounds capable of generating an acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

  Among the compounds that generate an acid upon irradiation with actinic rays or radiation, compounds represented by the following general formulas (ZI), (ZII), and (ZIII) can be exemplified.

In general formulas (ZI) to (ZIII),
R ₂₀₁ to R ₂₀₇ each independently represent an organic group.
The number of carbons in the organic group R ₂₀₁ to R ₂₀₇ generally has 1 to 30, preferably 1 to 20.
Two members out of R _{201 to} R ₂₀₃ may combine to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. Examples of the group formed by combining two of R _{201 to} R ₂₀₃ include an alkylene group (eg, butylene group, pentylene group).
X ⁻ represents a non-nucleophilic anion, preferably an organic anion having a carbon atom such as a sulfonate anion, a carboxylate anion, a bis (alkylsulfonyl) amide anion, a tris (alkylsulfonyl) methide anion, BF ⁴⁻ , PF ^{6-, SbF 6-} and the like, preferably an organic anion having a carbon atom (hereinafter, referred to as organic anions.).

  Preferable organic anions include organic anions represented by the following general formula.

In the above general formula, Rc ₁ represents an organic group.
Examples of the organic group for Rc ₁ include those having 1 to 30 carbon atoms, and preferably an alkyl group, a cycloalkyl group, an aryl group, or a plurality thereof, which may be substituted, is a single bond, —O—, — _{CO 2 -, - S -,} - SO 3 -, - SO 2 N (Rd 1) - can be exemplified linked group a linking group such as.
Rd ₁ represents a hydrogen atom or an alkyl group.
Rc ₃ , Rc ₄ and Rc ₅ each independently represents an organic group.
Examples of the organic group of Rc ₃ , Rc _4, and Rc ₅ include the same organic groups as those of Rc ₁ , and preferably a perfluoroalkyl group having 1 to 4 carbon atoms.
Rc ₃ and Rc ₄ may be bonded to form a ring.
Examples of the group formed by combining Rc ₃ and Rc ₄ include an alkylene group, a cycloalkylene group, and an arylene group. Preferably, it is a C2-C4 perfluoroalkylene group.
The organic group of Rc ₁ and Rc ₃ to Rc _5, preferably a phenyl group in which one position is substituted with a fluorine atom or a fluoroalkyl-substituted alkyl group with a group, a fluorine atom or a fluoroalkyl group. By having a fluorine atom or a fluoroalkyl group, the acidity of the acid generated by light irradiation is increased and the sensitivity is improved. Further, when Rc ₃ and Rc ₄ are bonded to form a ring, the acidity of the acid generated by light irradiation is increased, and the sensitivity is improved, which is preferable.

As the specific substituent of R _{201 to} R ₂₀₃ in the general formula (ZI), it is preferable that at least one of the aryl groups of the triarylsulfonium salt has an electron-withdrawing group as a substituent, and further bonded to the aryl skeleton It is preferable that the sum of Hammett values of the substituents to be greater than 0.18.

Here, the electron-withdrawing group means a substituent having a Hammett value (Hammet substituent constant σ) larger than 0. In the present invention, from the viewpoint of increasing sensitivity, the sum of Hammett values of substituents bonded to the aryl skeleton in the specific photoacid generator is preferably 0.18 or more, more preferably greater than 0.46. Preferably, it is more preferably larger than 0.60.
The Hammett value represents the degree of electron withdrawing property of a cation having a triarylsulfonium salt structure, and there is no particular upper limit from the viewpoint of increasing sensitivity, but from the viewpoint of reactivity and stability. , More than 0.46 and less than 4.0, more preferably more than 0.50 and less than 3.5, and particularly preferably more than 0.60 and less than 3.0.

In addition, the Hammett value in the present invention uses the numerical value described in Naoki Inamoto, edited by Chemistry Seminar 10 Hammett's Rule-Structure and Reactivity (1983, published by Maruzen Co., Ltd.).
Examples of the electron-withdrawing group introduced into the aryl skeleton include a trifluoromethyl group, a halogen atom, an ester group, a sulfoxide group, a cyano group, an amide group, a carboxyl group, and a carbonyl group. The Hammett values of these substituents are shown below. A trifluoromethyl group (—CF ₃ , m: 0.43, p: 0.54), a halogen atom [eg, —F (m: 0.34, p: 0.06), —Cl (m: 0. 37, p: 0.23), -Br (m: 0.39, p: 0.23), -I (m: 0.35, p: 0.18)], an ester group (for example, -COCH ₃ , O: 0.37, p: 0.45), sulfoxide group (for example, —SOCH ₃ , m: 0.52, p: 0.45), cyano group (—CN, m: 0.56, p: 0.66), an amide group (for example, —NHCOCH ₃ , m: 0.21, p: 0.00), a carboxyl group (—COOH, m: 0.37, p: 0.45), a carbonyl group (— CHO, m: 0.36, p: (043)) and the like. The parenthesis represents the introduction position of the substituent in the aryl skeleton and the Hammett value, and (m: 0.50) is the Hammett value of 0.50 when the substituent is introduced at the meta position. It shows that there is.

Among these substituents, nonionic substituents such as a halogen atom and a halogenated alkyl group are preferable from the viewpoint of hydrophobicity. Among them, —Cl is preferable from the viewpoint of reactivity, and imparts hydrophobicity. from the viewpoint, -F, -CF 3, -Cl, -Br are preferable.

  These substituents may be introduced into any one of the three aryl skeletons of the triarylsulfonium salt structure, or may be introduced into two or more aryl skeletons. Moreover, the substituent introduced into each of the three aryl skeletons may be one or plural. In the present invention, the sum of Hammett values of substituents introduced into these aryl skeletons is preferably more than 0.18, more preferably more than 0.46. The number of substituents to be introduced is arbitrary. For example, only one substituent having a particularly large Hammett value (for example, a Hammett value exceeding 0.46 alone) may be introduced into one position of an aryl skeleton having a triarylsulfonium salt structure. Moreover, for example, a plurality of substituents introduced and the sum of the Hammett values exceeding 0.46 may be introduced.

As described above, since the Hammett value of the substituent varies depending on the position of introduction, the sum of Hammett values in the specific photoacid generator according to the present invention is determined by the type of substituent, the introduction position, and the number of introductions. become.
The Hammett value is usually expressed in the m-position and p-position, but in the present invention, the substituent effect at the o-position is calculated as the same value as the p-position as an index of electron withdrawing. Preferred substitution positions are preferably m-position and p-position, and most preferably p-position, from the viewpoint of synthesis.
Preferred in the present invention is a sulfonium salt that is tri- or more substituted with a halogen atom, and most preferred is a sulfonium salt that is tri-substituted with a chloro group, specifically, each of the three aryl skeletons. A halogen atom, most preferably a triarylsulfonium salt structure in which —Cl is introduced, is preferable, and a structure in which —Cl is substituted at the p-position is more preferable.

  Examples of the sulfonate anion contained in the triarylsulfonium salt contained in the composition of the present invention include an arylsulfonate anion and an alkanesulfonate anion, which are substituted with a fluorine atom or an organic group having a fluorine atom. Anions are preferred.

  Compounds having a triarylsulfonium salt structure are disclosed in, for example, J. Org. Am. Chem. Soc. 112 (16), 1990; 6004-6015, J.A. Org. Chem. 1988; It can be easily synthesized by the methods described in 5571-5573, WO02 / 081439A1 pamphlet, or European Patent (EP) No. 1113005.

  Although a specific example is given below, it is not limited to these.

Among the compounds that generate an acid upon irradiation with actinic rays or radiation, preferred compounds (photoacid generators) include pKa as strong as 2 or less as a generated acid, alkyl or arylcarboxylic acid substituted with sulfonic acid or an electron withdrawing group. Acid, disulfonylimide substituted with an electron withdrawing group, and the like are preferable. Examples of the electron withdrawing group include a halogen atom such as an F atom, a haloalkyl group such as a trifluoromethyl group, a nitro group, and a cyano group.
Examples of the photoacid generator include N-hydroxyimide sulfonate compounds and oxime sulfonates.

-Imidosulfonate compound-
Preferred imide sulfonate compounds as photoacid generators include compounds of the following general formula.

In the general formula (I), C ₁ (carbon atom) and C ₂ (carbon atom) are bonded by a single bond or a double bond, and R ₁ or R ₂ may be the same or different, and the following (1) Represents any one of (4), (1) each independently contains a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, and (2) one or more heteroatoms together with C ₁ and C ₂ A group that forms a good monocycle or polycycle, (3) a group that forms a condensed aromatic ring containing C ₁ and C ₂ , and (4) a residue that contains N-sulfonyloxyimide.
R ₃ represents an alkyl group, a halogenated alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or a camphor group.

In the general formula (I), when R ₁ and R ₂ correspond to the case of (1), examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert- C1-C4 alkyl groups, such as a butyl group, are mentioned. Examples of the cycloalkyl group include those having 3 to 8 carbon atoms such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Examples of the aryl group include those having 6 to 14 carbon atoms such as a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a naphthyl group.
Further, when R ₁ and R ₂ hits the casing (2), mention may be made, for example following such partial structures.

When R ₁ and R ₂ correspond to the case of (3), for example, the following partial structures can be given.

When R ₁ and R ₂ correspond to the case of (4), so-called at least two N-sulfonyloxyimide residues are single bonds at the R ₁ and R ₂ moieties having the partial structures of (1) to (3) above. Or the thing couple | bonded with the following bivalent organic groups can be mention | raise | lifted. However, the following linking groups are used alone or in combination of two or more.
[Divalent organic _{group]: -O -, - S -,} - SO -, - SO 2 -, - NH -, - CO -, - CO 2 -, - NHSO 2 -, - NHCO -, - NHCO 2 −,

Examples of the alkyl group for R ₃ include linear or branched alkyl groups having 1 to 20 carbon atoms. Preferred is a linear or branched alkyl group having 1 to 16 carbon atoms, and more preferred is one having 1 to 12 carbon atoms. In the case of an alkyl group having 21 or more carbon atoms, sensitivity and resolving power decrease, which is not preferable. Examples of the halogenated alkyl group include those in which one or two or more hydrogen atoms of the alkyl group are halogenated. Examples of the halogen atom to be substituted include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Preferred are a fluorine atom, a chlorine atom and a bromine atom, and particularly preferred is a fluorine atom. However, the halogen atom to be substituted may be plural types per molecule. Examples of the cyclic alkyl group include cycloalkyl groups having 3 to 12 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, and cyclooctyl group, and polycyclic substituents such as norbornyl group, adamantyl group, and tricyclodecanyl group. I can give you. Examples of the alkenyl group include linear or branched alkenyl groups having 1 to 20 carbon atoms. Preferred is a linear or branched alkenyl group having 1 to 16 carbon atoms, and more preferred is one having 1 to 12 carbon atoms. In the case of an alkenyl group having 21 or more carbon atoms, sensitivity and resolving power decrease, which is not preferable.

Examples of the aryl group of R ₃ include a phenyl group and a naphthyl group, and examples of the aralkyl group include a benzyl group. Examples of the substituent of the aryl group and the aralkyl group include a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a tert-butyl group, a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a phenyl group, a toluyl group, Aryl group such as xylyl group, mesityl group, methoxy group, ethoxy group, propoxy group, isopropoxy group, sec-butoxy group, tert-butoxy group and other lower alkoxy groups, vinyl group, allyl group, propenyl group, butenyl group, etc. And an acyl group such as alkenyl group, formyl group and acetyl group, and halogen atoms such as hydroxy group, carboxy group, cyano group, nitro group, fluorine atom, chlorine atom, bromine atom and iodine atom. Preferably, a lower alkyl group such as methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, cyclohexyl group, phenyl group, toluyl group, methoxy group, ethoxy group, propoxy group, isopropoxy group, sec-butoxy Group, lower alkoxy group such as tert-butoxy group, halogen atom such as cyano group, nitro group, fluorine atom, chlorine atom, bromine atom and iodine atom. Two or more kinds of substituents on the aryl group and the aralkyl group may be used.
Specific examples of these compounds are shown below, but are not limited thereto.

-Oxime sulfonate compound-
Preferred examples of the oxime sulfonate compound as a photoacid generator include compounds of the following general formula (II).

In the general formula (II), R ₄ and R ₅ represent an alkyl group having 1 to 16 carbon atoms, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group, and a substituent which may have a substituent. An aryl group, a heteroaryl group, or a cyano group which may be present. R ₄ and R ₅ are each an optionally substituted alkylene chain having 2 to 8 carbon atoms, an alkenylene chain, an alkynylline chain, or an optionally substituted phenylene, freelen, thienylene, It may be bonded to R ₄ or R _{5 of} another compound represented by the general formula (II) via a linking chain containing —O—, —S—, —N—, and —CO—. That is, the compound represented by the general formula (II) includes those having two or three oxime sulfonate structures via a linking chain.
R ₆ represents an optionally substituted alkyl group having 1 to 16 carbon atoms, a cycloalkyl group, and an optionally substituted aryl group.

Examples of the alkyl group having 1 to 16 carbon atoms in R _{4 to} R ₆ include methyl group, ethyl group, propyl group, i-propyl group, butyl group, i-butyl group, t-butyl group, t-amyl group, n-hexyl group, n-octyl group, i-octyl group, n-decyl group, undecyl group, dodecyl group, hexadecyl group and other alkyl groups, trifluoromethyl group, perfluoropropyl group, perfluorobutyl group, perfluoro-t- Examples thereof include a butyl group, a perfluorooctyl group, a perfluoroundecyl group, and a 1,1-bistrifluoromethylethyl group.

Examples of the alkenyl group in R ₄ and R ₅ include allyl group, methallyl group, vinyl group, methylallyl group, 1-butenyl group, 3-butenyl group, 2-butenyl group, 1,3-pentadienyl group, 5-hexenyl group, A 2-oxo-3-pentenyl group, a decapentaenyl group, a 7-octenyl group and the like can be mentioned.

Examples of the alkynyl group in R ₄ and R ₅ include ethynyl group, propargyl group, 2-butynyl group, 4-hexynyl group, 2-octynyl group, phenylethynyl group, cyclohexylethynyl group and the like.

Examples of the cycloalkyl group in R _{4 to} R ₆ include those having 3 to 8 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group, which may have a substituent.

Examples of the cycloalkenyl group in R ₄ and R ₅ include a cyclobutenyl group, a cyclohexenyl group, a cyclopentadienyl group, a bicyclo [4.2.4] dodec-3,7-dien-5-yl group, and the like.

Examples of the aryl group in R _{4 to} R ₆ include those having 6 to 14 carbon atoms, such as a phenyl group, a tolyl group, a methoxyphenyl group, and a naphthyl group, which may have a substituent.

The above substituents include alkyl groups, cycloalkyl groups, alkoxy groups, halogen atoms (fluorine atoms, chlorine atoms, iodine atoms), cyano groups, hydroxy groups, carboxy groups, nitro groups, aryloxy groups, alkylthio groups, aralkyls. And groups represented by the following general formula (1A).
Here, the alkyl group and the cycloalkyl group have the same meanings as described above. Examples of the alkoxy group include those having 1 to 4 carbon atoms such as methoxy group, ethoxy group, hydroxyethoxy group, propoxy group, n-butoxy group, isobutoxy group, sec-butoxy group and t-butoxy group. Examples of the aralkyl group include a benzyl group, a naphthylmethyl group, a furyl group, and a thienyl group.

In the formula (1A), _{R 4} and _{R 5} have the same meanings as _{R 4} and _{R 5} in the general formula (II).

  Specific examples of the compound represented by the general formula (II) are shown below, but the present invention is not limited thereto.

Specific examples of more preferable oxime sulfonate compounds include the following (z66) to (z70).

-Nitrobenzyl sulfonate compound-
Examples of the nitrobenzyl sulfonate compound include compounds represented by the general formula (III).

(Z in this formula is alkyl group, aryl group, alkylaryl group, halogen-substituted alkyl group, halogen-substituted aryl group, halogen-substituted alkylaryl group, nitro-substituted aryl group, nitro-substituted An alkylaryl group, an aryl group having a nitro substituent and a halogen substituent, an alkylaryl group having a nitro substituent and a halogen substituent, or a formula —C ₆ H ₄ SO ₃ CHR′C ₆ H _4-m Q _m ( Represents a group having NO ₂ ).
R ′ represents a hydrogen atom, a methyl group, or a nitro-substituted aryl group, m represents 0, 1 or 2, and when m is 1 or 2, each Q is a hydrocarbon group, a hydrocarbonoxy group, A nitro group, a halogen atom or an organosilicon group is independently represented, provided that Q is not an acidic group. R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an acyl group having 1 to 4 carbon atoms. )
Specific examples of the compound represented by the general formula (III) include the following compounds.

  In the treatment liquid in the present invention, the blending amount of the photoacid generator is preferably 0.5 to 30 parts by mass, more preferably 2 to 20 parts by mass with respect to 100 parts by mass of the total amount of the flocculant. An acid generator can be used individually by 1 type or in combination of 2 or more types.

(A2) Thermal acid generator The acid generator in the present invention is preferably a thermal acid generator that generates an acid by heat, and usually has a thermal decomposition point of 130 ° C to 250 ° C, preferably 150 ° C to 220 ° C. It is a compound of this. Specific examples include compounds that generate a low nucleophilic acid such as sulfonic acid, carboxylic acid, and disulfonylimide by heating.
The acid generated is preferably a sulfonic acid having a strong pKa of 2 or less, an alkyl or aryl carboxylic acid substituted with an electron withdrawing group, or a disulfonylimide substituted with an electron withdrawing group. Examples of the electron withdrawing group include a halogen atom such as an F atom, a haloalkyl group such as a trifluoromethyl group, a nitro group, and a cyano group.
As the thermal acid generator, a photoacid generator that generates an acid by the above-described exposure can be applied. Examples include onium salts such as sulfonium salts and iodonium salts, N-hydroxyimide sulfonate compounds, oxime sulfonates, o-nitrobenzyl sulfonates, and the like. Of these, N-hydroxyimide sulfonate compounds, oxime sulfonates, and o-nitrobenzyl sulfonates are preferred.

  In the present invention, the thermal acid generator is preferably a compound that generates sulfonic acid by heat.

  As the compound that generates sulfonic acid, a sulfonic acid ester represented by the following general formula (IV) is preferable.

In the above formula, R ′ and R ″ are each independently a linear or branched or cyclic alkyl group having 1 to 10 carbon atoms which may have a substituent or a carbon number which may have 6 substituents. And an aryl group of ˜20.Substituents include a hydroxyl group, a halogen atom, a cyano group, a vinyl group, an acetylene group, and a linear or cyclic alkyl group having 1 to 10 carbon atoms.
Preferable specific examples of the sulfonic acid ester include the following.

  The molecular weight of the sulfonic acid ester is generally 230 to 1000, preferably 230 to 800.

  As the sulfonic acid ester, a compound represented by the following general formula (2) can be more preferably used from the viewpoint of heat resistance.

A represents an h-valent linking group.
R ₀ represents an alkyl group, an aryl group, an aralkyl group, or a cyclic alkyl group.
R _{0 ′} represents a hydrogen atom, an alkyl group, or an aralkyl group.
h represents an integer of 2 to 8.

Examples of the h-valent linking group represented by A include an alkylene group (eg, methylene, ethylene, propylene, etc.), a cycloalkylene group (eg, cyclohexylene, cyclopentylene, etc.), an arylene group (1,2-phenylene, 1,3-phenylene, 1,4-phenylene, naphthylene, etc.), ether group, carbonyl group, ester group, amide group, and any hydrogen atom of a divalent group such as a group obtained by combining these groups with h- An h-valent group excluding two may be mentioned.
A is a linking group having 1 to 15 carbon atoms, preferably a linking group having 1 to 10 carbon atoms, and more preferably a linking group having 1 to 6 carbon atoms.
The alkyl group for R ₀ and R _{0 ′ is} an alkyl group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 15 carbon atoms, and more preferably an alkyl group having 1 to 8 carbon atoms. Specific examples include methyl, ethyl, propyl, butyl, hexyl, octyl and the like.
The aralkyl group for R ₀ and R _{0 ′ is} an aralkyl group having 7 to 25 carbon atoms, preferably an aralkyl group having 7 to 20 carbon atoms, and more preferably an aralkyl group having 7 to 15 carbon atoms. Specific examples include benzyl, toluylmethyl, mesitylmethyl, phenethyl and the like.
The cyclic alkyl group for R _{0 is} a cyclic alkyl group having 3 to 20 carbon atoms,
Preferably it is a C4-C20 cyclic alkyl group, More preferably, it is a C5-C15 cyclic alkyl group. Specific examples include cyclopentyl, cyclohexyl, norbornyl, camphor group and the like.

  The linking group as A may further have a substituent. The substituent is an alkyl group (an alkyl group having 1 to 10 carbon atoms, specifically methyl, ethyl, propyl, butyl, hexyl). Octyl, etc.), aralkyl groups (aralkyl groups having 7 to 15 carbon atoms, specifically benzyl, toluylmethyl, mesitylmethyl, phenethyl, etc.), aryl groups (aryl groups having 6 to 10 carbon atoms, specifically Are phenyl, toluyl, xylyl, mesityl, naphthyl, etc.), an alkoxy group (the alkoxy group may be linear, branched or cyclic, and is an alkoxy group having 1 to 10 carbon atoms, specifically, Methoxy, ethoxy, linear or branched propoxy, linear or branched butoxy, linear or branched pentoxy, cyclopentyloxy, cyclohexyloxy, etc.) A reeloxy group (an aryloxy group having 6 to 10 carbon atoms, specifically phenoxy, toluyloxy, 1-naphthoxy, etc.), an alkylthio group (which may be linear, branched or cyclic, the number of carbon atoms) 1 to 10 alkylthio groups, specifically methylthio, ethylthio, linear or branched propylthio, cyclopentylthio, cyclohexylthio), arylthio groups (arylthio groups having 6 to 10 carbon atoms, specifically phenylthio , Toluoylthio, 1-naphthylthio, etc.), acyloxy groups (acyloxy groups having 2 to 10 carbon atoms, specifically acetoxy, propanoyloxy, benzoyloxy, etc.), alkoxycarbonyl groups (alkoxycarbonyl having 1 to 10 carbon atoms) Groups such as methoxycarbonyl, ethoxycarbonyl, Or branched propoxycarbonyl, cyclopentyloxycarbonyl, cyclohexyloxycarbonyl, etc.), can be exemplified.

In the general formula (2), R ₀ is preferably an alkyl group or an aryl group. R _{0 ′} is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom, a methyl group or an ethyl group, and most preferably a hydrogen atom.

  Examples of the sulfonic acid ester of the present invention include the following specific compounds, but are not limited thereto.

(A3) Sensitizer In the treatment liquid of the present invention, it is preferable to add a sensitizer in order to promote the decomposition in the combination with the sulfonium salt. The sensitizer absorbs actinic rays or radiation and enters an electronically excited state. The sensitizer in an electronically excited state comes into contact with sulfonium, and effects such as electron transfer, energy transfer, and heat generation occur. As a result, the polymerization initiator undergoes a chemical change and decomposes to generate radicals, acids or bases.

Examples of preferred sensitizers include compounds belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene, anthracene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanine (Eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, , Squalium), coumarins (for example, 7-diethylamino 4-methylcoumarin). Among them, an anthracene derivative is particularly preferable as a sensitizer.

  Preferable specific examples include (C-1) to (C-26) shown below, but are not limited thereto.

  As the sensitizer as described above, a commercially available one may be used, or it may be synthesized by a known synthesis method.

  20-200 mass parts is preferable with respect to 100 mass parts of said photoacid generators, and, as for the addition amount of a sensitizer, 30-150 mass parts is more preferable.

(Flocculant)
The aggregating agent for aggregating (fixing) the components in the ink composition is preferably at least one selected from acidic substances and polyvalent metal salts. In the present specification, the acidic substance and the polyvalent metal salt are sometimes referred to as “fixing agent”.
The acidic substance in the present invention can fix (aggregate) components in the ink composition by contacting with the ink composition on paper, and functions as a fixing agent. For example, by applying the treatment liquid to the coated paper, in the state where the acidic substance is present on the paper, by further applying the ink composition and contacting the acidic substance, the components in the ink composition are aggregated. Thus, the ink composition can be fixed on paper.

-Acidic substances-
Examples of acidic substances 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, and These salts etc. are mentioned suitably.

Among them, acidic substances with high water solubility are preferable. Also, from the viewpoint of fixing the whole ink by reacting with the ink composition, an acidic substance having a valence of 3 or less is preferable, and an acidic substance having a valence of 2 or more and not more than 3 is particularly preferable.
An acidic substance may be used individually by 1 type, and may use 2 or more types together.

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

(Polyvalent metal salt)
The polyvalent metal salt in the present invention is a salt of a compound containing a divalent or higher metal such as an alkaline earth metal or a zinc group metal, and examples thereof include salts of metal ions such as Ca ²⁺ , Cu ²⁺ and Al ^3+. Can do.
In the present invention, the agglomeration reaction of the ink composition when the ink composition is applied to the coated paper to which the treatment liquid has been applied is performed by dispersing particles dispersed in the ink composition, for example, a colorant represented by a pigment, This can be achieved by reducing the dispersion stability of particles such as resin particles and increasing the viscosity of the entire ink composition.
For example, when particles such as pigments or 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 flocculant contained in the treatment liquid is preferably at least one polyvalent metal salt selected from a divalent metal salt and a trivalent metal salt from the viewpoint of the aggregation reaction, A trivalent polyvalent metal salt is preferred.

  From the above viewpoint, the polyvalent metal salt that can be used in the treatment liquid of the present invention is preferably at least one of the following salts of polyvalent metal ions and anions and polyaluminum chloride.

Examples of the polyvalent metal ion 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.
The salt is a metal salt composed of the above polyvalent metal ions and an anion that binds to these ions, but it must be 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 water-soluble 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 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.

The content of the flocculant is preferably 15% by mass or more and 40% by mass or less, and preferably 15% by mass to 35% by mass with respect to the total mass of the treatment liquid, from the viewpoint of improving the aggregation rate and offset resistance. It is preferably 20% by mass to 30% by mass.
When the acidic substance concentration is 15% by mass or more when the acidic substance is used as the aggregating agent, the reaction of aggregating the components in the ink composition effectively proceeds and the components in the ink composition are easily fixed. Preferably, it is 40% by mass or less based on the total mass of the treatment liquid from the viewpoint of the stability of the treatment liquid.

The amount of the flocculant 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 ² from the viewpoint that the ink composition is easily fixed. it is preferably to 4.0 g / ^{m 2,} more preferably ^{0.9g / m 2 ~3.75g / m 2} .

(Other ingredients)
The treatment liquid in the present invention may generally contain a water-soluble organic solvent in addition to the acid generator and the flocculant, and can be constituted using other various additives. The details of the water-soluble organic solvent and other various additives are the same as those in the ink composition described later.

Even if the treatment liquid is applied to the entire recording medium (coating paper), it is partially applied to the area where an ink composition is applied by an ink jet method in the subsequent ink application process. It may be a partial grant that is given to.
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 to the entire paper.

  Examples of the method for applying the flocculant by controlling the amount of the flocculant 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.

The surface tension (25 ° C.) of the treatment liquid is preferably 20 mN / m or more and 60 mN / m or less. More preferably, it is 25 mN / m or less and 50 mN / m or less, More preferably, it is 25 mN / m or more and 45 mN / m or less.
The surface tension is measured using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) under a condition of 25 ° C.

The viscosity (25 ° C.) of the treatment liquid is preferably in the range of 1 to 30 mPa · s, more preferably in the range of 1 to 20 mPa · s, and further in the range of 2 to 15 mPa · s from the viewpoint of the aggregation rate of the ink composition. A range of 2 to 10 mPa · s is particularly preferable.
In the present invention, the viscosity of the treatment liquid is measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD) under the condition of 25 ° C.

[Ink composition]
The ink composition in the present invention preferably contains at least one colorant and further contains a water-soluble organic solvent and water. If necessary, it is configured to include other components.
The ink composition according to the present invention (hereinafter sometimes simply referred to as “ink”) 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). Can be selected to form an image. When forming a full color image, the ink composition can be used as 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, ink compositions having red (R), green (G), blue (B), and white (W) tones other than yellow (Y), magenta (M), and cyan (C), and so-called printing fields. Can be used as an ink composition having a special color.
The ink composition of each color tone can be prepared by changing the hue of a colorant (for example, a pigment) as desired.
The ink composition in the present invention does not substantially contain a polymerizable compound. Here, “substantially not containing” means accepting the presence of inevitable impurities.

-Colorant-
The ink composition in the invention contains at least one colorant (hereinafter also referred to as a color material). The colorant is not particularly limited as long as it has a function of forming an image by coloring, and pigments, dyes, colored particles, and the like can be used. Among these, a pigment is preferable, a water-dispersible pigment is more preferable, and a pigment coated with a water-insoluble polymer dispersant is further preferable.

Specific examples of the water-dispersible pigment include the following pigments (1) to (4).
(1) An encapsulated pigment, that is, a polymer dispersion in which a pigment is contained in polymer particles. More specifically, the pigment is coated with a hydrophilic water-insoluble resin, and is made hydrophilic by a resin layer on the pigment surface. Thus, the pigment can be dispersed in water (hereinafter sometimes referred to as “resin-coated pigment”).
(2) Self-dispersing pigments, that is, pigments having at least one hydrophilic group on the surface and exhibiting at least one of water dispersibility and water solubility in the absence of a dispersant, more specifically, mainly carbon black Etc. are made hydrophilic by surface oxidation treatment so that the pigment alone is dispersed in water.
(3) A resin-dispersed pigment, that is, a pigment dispersed with a water-soluble polymer compound having a weight average molecular weight of 50,000 or less.
(4) A surfactant-dispersed pigment, that is, a pigment dispersed with a surfactant.
Of these, (1) encapsulated pigments and (2) self-dispersing pigments are preferred, and (1) encapsulated pigments are particularly preferred.

Here, (1) the encapsulated pigment will be described in detail.
The encapsulated pigment resin (hereinafter sometimes referred to as “water-insoluble polymer dispersant”) is not limited, but has a self-dispersibility or solubility in a mixed solvent of water and a water-soluble organic solvent. And a high molecular compound having an anionic group (acidic). This resin usually has a number average molecular weight of preferably about 1,000 to 100,000, particularly preferably about 3,000 to 50,000. Further, this resin is preferably one that is dissolved in a water-soluble organic solvent to form a solution. When the number average molecular weight of the resin is within this range, it can function as a coating film for the pigment or as a coating film when used as an ink. The resin is preferably used in the form of an alkali metal or organic amine salt.

Specific examples of encapsulated pigment resins include thermoplastic, thermosetting or modified acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenol, silicone, or fluorine. Resins: Polyvinyl resins such as vinyl chloride, vinyl acetate, polyvinyl alcohol, or polyvinyl butyral, polyester resins such as alkyd resins and phthalic resins, melamine resins, melamine formaldehyde resins, aminoalkyd co-condensation resins, urea resins, urea Examples thereof include amino materials such as resins, and materials having an anionic group such as copolymers or mixtures thereof.
Among these resins, an anionic acrylic resin is, for example, an acrylic monomer having an anionic group (hereinafter referred to as “anionic group-containing acrylic monomer”) and, if necessary, the anionic group-containing acrylic monomer. It is obtained by polymerizing another polymerizable monomer in a solvent. Examples of the anionic group-containing acrylic monomer include an acrylic monomer having one or more anionic groups selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphonic group. Among these, an acrylic monomer having a carboxyl group is used. Particularly preferred.

  Specific examples of the acrylic monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid and the like. Among these, acrylic acid or methacrylic acid is preferable.

The encapsulated pigment can be produced by the conventional physical and chemical methods using the above components. For example, as described in JP-A-9-151342, JP-A-10-140065, JP-A-11-209672, JP-A-11-172180, JP-A-10-25440, or JP-A-11-43636. It can be manufactured by a method.
Specific examples include the phase inversion emulsification method and the acid precipitation method described in JP-A-9-151342 and JP-A-10-140065. Among them, the phase inversion emulsification method is preferable in terms of dispersion stability. preferable. The phase inversion emulsification method will be described later.

The self-dispersing pigment is also a preferred example. The self-dispersing pigment refers to a large number of hydrophilic functional groups and / or salts thereof (hereinafter referred to as “dispersibility-imparting groups”) directly on the pigment surface or indirectly via an alkyl group, an alkyl ether group, an aryl group, or the like. Are pigments that can be dispersed in an aqueous medium without using a dispersant for dispersing the pigment. Here, “dispersed in an aqueous medium without using a dispersant” means that the pigment can be dispersed in an aqueous medium without using a dispersant for dispersing the pigment.
Inks containing self-dispersing pigments as colorants usually do not need to contain dispersants to disperse the pigments, so there is almost no foaming due to defoaming loss due to the dispersants, and ejection stability It is easy to prepare an ink that excels. The dispersibility-imparting groups to be bonded to the surface of the self-dispersing _{pigment, -COOH, -CO -, - OH} , -SO 3 H, -PO 3 H 2 and quaternary ammonium and can be exemplified salts thereof, these Is bonded by grafting a pigment having a dispersibility-imparting group or an active species having a dispersibility-imparting group to the pigment surface by subjecting the pigment to physical treatment or chemical treatment. Examples of the physical treatment include vacuum plasma treatment. Examples of the chemical treatment include a wet oxidation method in which the pigment surface is oxidized with an oxidizing agent in water, and a method in which a carboxyl group is bonded via a phenyl group by bonding p-aminobenzoic acid to the pigment surface. Can be exemplified.
For example, a self-dispersing pigment that is surface-treated by oxidation treatment with hypohalous acid and / or hypohalite or oxidation treatment with ozone can be mentioned as a preferred example.
Commercially available products may be used as the self-dispersing pigment. Specifically, Microjet CW-1 (trade name; manufactured by Orient Chemical Industry Co., Ltd.), CAB-O-JET200, CAB-O-JET300 (trade name) ; Manufactured by Cabot Corporation).

-A) Phase inversion emulsification method-
The phase inversion emulsification method is basically a self-dispersion (phase inversion emulsification) method in which a mixed melt of a resin having a self-dispersing ability or a dissolving ability and a pigment is dispersed in water. Here, the mixed molten material refers to a mixed state without dissolving, a mixed state with dissolved, or a state including both of these states. A more specific production method of the “phase inversion emulsification method” includes the method described in JP-A-10-140065.

(Pigment)
There is no restriction | limiting in particular as a pigment used as a coloring agent in this invention, According to the objective, it can select suitably, For example, any of an organic pigment and an inorganic pigment may be sufficient.
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 carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, a thermal method, is mentioned, for example.

The above colorants may be used alone or in combination of a plurality of types selected from within each group or between each group.
The content of the colorant (particularly the pigment) in the ink composition is, from the viewpoint of color density, granularity, ink stability, and ejection reliability, the ink composition (colorant, resin particles, water-soluble organic solvent, and The amount of 1 to 25% by mass is preferable, and the amount of 5 to 20% by mass is more preferable with respect to the total mass of (including water).

(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.
The monomer constituting the hydrophilic structural unit is not particularly limited as long as it is a monomer containing a hydrophilic group. Examples of the hydrophilic group include a nonionic group, a carboxyl group, a sulfonic acid group, and a phosphoric acid group. The nonionic group has the same meaning as the nonionic group in the self-dispersing polymer.
From the viewpoint of dispersion stability, the hydrophilic structural unit in the present invention preferably contains at least a carboxyl group, and preferably has a form containing both 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 colorant in the present invention is preferably 10 to 100% by mass of the dispersant with respect to the colorant from the viewpoint of pigment dispersibility, ink colorability, and dispersion stability. -70 mass% is more preferable, and 30-50 mass% is especially preferable.
When the content of the dispersant in the colorant is in the above range, the colorant is preferably coated with an appropriate amount of the dispersant, and it is easy to obtain colored particles having a small particle size and excellent stability over time.

  The colorant in the present invention may contain other dispersant 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.

-Water-soluble organic solvent-
The ink composition in the invention preferably contains at least one water-soluble organic solvent as a solvent for the ink composition. By containing the water-soluble organic solvent, it is possible to obtain the effect of preventing drying, wetting or promoting penetration. In order to prevent drying, the ink composition adheres and dries at the ink discharge port of the ejection nozzle to form an aggregate and is used as a drying preventing agent to prevent clogging. Low water-soluble organic solvents are preferred. Further, for penetration promotion, it can be used as a penetration enhancer 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, Alkyl alcohols having 1 to 4 carbon atoms such as butanol, propanol and isopropanol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-iso-propyl ether, ethylene glycol monobutyl ether (ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether), ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl Ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-iso-propyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monoethyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether ,Propylene glycol No ethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-t-butyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol Examples include glycol ethers such as mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, and tripropylene glycol monomethyl ether.
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.

  Further, the water-soluble organic solvent preferably contains at least one compound represented by the following structural formula (1) from the viewpoint of curling generation in the recording medium.

  In Structural Formula (1), l, m, and n each independently represent an integer of 1 or more, satisfying l + m + n = 3-15, and l + m + n is preferably in the range of 3-12, more preferably in the range of 3-10. preferable. When the value of l + m + n is 3 or more, a good curling suppression force is shown, and when it is 15 or less, a good discharge property is obtained. In the structural formula (1), AO represents ethyleneoxy (EO) and / or propyleneoxy (PO), and among them, a propyleneoxy group is preferable. Each AO in (AO) l, (AO) m, and (AO) n may be the same or different.

  Hereinafter, examples of the compound represented by the structural formula (1) are shown together with SP values (in parentheses). However, the present invention is not limited to this.

_{· NC 4 H 9 O (AO} ) 4 -H ( in AO = EO or PO, the ratio of EO: PO = 1: 1)
· _NC at _{4 H 9 O (AO) 10} -H AO = EO or PO, the ratio of EO: PO = 1: 1)
HO (A′O) ₄₀ −H (A′O = EO or PO, the ratio is EO: PO = 1: 3)
HO (A ″ O) ₅₅ −H (A ″ O = EO or PO, the ratio is EO: PO = 5: 6)
・ HO (PO) ₃ -H
・ HO (PO) ₇ -H
・ 1,2-Hexanediol

  The content of the compound represented by the structural formula (1) in the total water-soluble organic solvent is preferably 3% by mass or more, more preferably 4% by mass or more, and further preferably 5% by mass or more. By setting it in the above range, curling can be suppressed without deteriorating the stability and ejection properties of the ink, which is preferable.

A water-soluble organic solvent may be used individually by 1 type, or may be used in mixture of 2 or more types.
The content of the water-soluble organic solvent in the ink is preferably 1% by mass or more and 60% by mass or less, more preferably 5% by mass or more and 40% by mass or less.

-Water-
The ink composition in the present invention can contain water as an ink solvent, but the water content is not particularly limited. Especially, it is preferably 10% by mass or more and 99% by mass or less, and more preferably 30% by mass or more and 80% by mass or less. More preferably, it is 50 mass% or more and 70 mass% or less.

(Resin particles)
The ink composition of the present invention preferably contains at least one kind of resin particles. By including the resin particles, it is possible to effectively improve the fixability of the ink composition to the recording medium, the blocking resistance of the image, the offset resistance, and the abrasion resistance.
Also, the resin particles fix the image formed by the ink composition by aggregating or destabilizing the ink composition to increase the viscosity of the ink composition when it comes into contact with the treatment liquid or the paper region where it is dried. It preferably has a function. Such resin particles are preferably dispersed in at least one of water and an organic solvent.

  Examples of the resin particles include thermoplastic (meth) acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenolic, silicone, or fluorine resins, vinyl chloride, acetic acid. Examples thereof include resin particles composed of a polyvinyl resin such as vinyl, polyvinyl alcohol, or polyvinyl butyral, a polyester resin such as an alkyd resin or a phthalic acid resin, or a resin such as a copolymer or a mixture thereof.

  The resin particles in the present invention are preferably self-dispersing polymer particles from the viewpoints of ejection stability and liquid stability (particularly dispersion stability) when a colorant (particularly pigment) is used, and self-dispersing particles having a carboxyl group. Dispersible polymer particles are more preferred. Self-dispersing polymer particles (hereinafter, also referred to as “self-dispersing polymer particles”) are water-based in the absence of other surfactants due to functional groups (particularly acidic groups or salts thereof) possessed by the polymer itself. It means water-insoluble polymer particles which can be dispersed in a medium and do not contain a free emulsifier.

Here, the dispersed state means both an emulsified state (emulsion) in which a water-insoluble polymer is dispersed in a liquid state in an aqueous medium, and a dispersed state (suspension) in which a water-insoluble polymer is dispersed in a solid state in an aqueous medium. It includes the state of.
The water-insoluble polymer in the present invention is preferably a water-insoluble polymer that can be in a dispersed state in which the water-insoluble polymer is dispersed in a solid state from the viewpoint of aggregation rate and fixing property when a liquid composition is used.

  The dispersion state of the self-dispersing polymer particles refers to a solution in which 30 g of a water-insoluble polymer is dissolved in 70 g of an organic solvent (for example, methyl ethyl ketone), a neutralizing agent that can neutralize the salt-forming group of the water-insoluble polymer 100% If the group is anionic, sodium hydroxide, acetic acid if it is cationic) and 200 g of water are mixed and stirred (apparatus: stirring apparatus with stirring blades, rotation speed 200 rpm, 30 minutes, 25 ° C.), and then mixed. It means a state in which even after removing the organic solvent from the liquid, it can be visually confirmed that the dispersed state exists stably at 25 ° C. for at least one week.

  The water-insoluble polymer means a polymer having a dissolution amount of 10 g or less when the polymer is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., and the dissolution amount is preferable. Is 5 g or less, more preferably 1 g or less. The dissolution amount is the dissolution amount when neutralized with sodium hydroxide or acetic acid according to the kind of the salt-forming group of the water-insoluble polymer.

  The aqueous medium is configured to include water, and may include a water-soluble organic solvent as necessary. In the present invention, it is preferably composed of water and 0.2% by mass or less of a water-soluble organic solvent, more preferably composed of water. The water-soluble organic solvent is the same as the water-soluble organic solvent preferably contained in the ink composition, and preferred examples thereof are also the same.

The main chain skeleton of the resin constituting the resin particles in the present invention is not particularly limited, and examples thereof include vinyl polymers, condensation polymers (epoxy resins, polyesters, polyurethanes, polyamides, celluloses, polyethers, polyureas, polyimides, polycarbonates, etc. ) Can be used. Among them, vinyl polymers are particularly preferable, and (meth) acrylic resin particles are more preferable from the viewpoint of dispersion stability of the resin particles.
The (meth) acrylic resin means a methacrylic resin and an acrylic resin.

Preferable examples of the vinyl polymer and the monomer constituting the vinyl polymer include those described in JP-A Nos. 2001-181549 and 2002-88294. In addition, radical transfer of vinyl monomers using dissociable groups (or substituents that can be induced to dissociable groups), polymerization initiators, and iniferters, or dissociable groups on either initiators or terminators A vinyl polymer in which a dissociable group is introduced at the end of a polymer chain by ionic polymerization using a compound having (or a substituent that can be derived from a dissociable group) can also be used.
Moreover, as a suitable example of the monomer which comprises a condensation system polymer and a condensation system polymer, what is described in Unexamined-Japanese-Patent No. 2001-247787 can be mentioned.

  The self-dispersing polymer particles in the present invention are, from the viewpoint of self-dispersibility, a hydrophilic structural unit, a structural unit derived from an aromatic group-containing monomer as a hydrophobic structural unit, and a structural unit derived from an alicyclic monomer. It is preferable to contain a water-insoluble polymer containing at least one of the above.

The hydrophilic structural unit is not particularly limited as long as it is derived from a hydrophilic group-containing monomer, and even if it is derived from one kind of hydrophilic group-containing monomer, it contains two or more hydrophilic groups. It may be derived from a monomer. The hydrophilic group is not particularly limited, and may be a dissociable group or a nonionic hydrophilic group.
In the present invention, the hydrophilic group is preferably a dissociable group and more preferably an anionic dissociable group from the viewpoint of promoting self-dispersion and the stability of the formed emulsified or dispersed state. Examples of the dissociable group include a carboxyl group, a phosphoric acid group, and a sulfonic acid group. Among them, a carboxyl group is preferable from the viewpoint of fixability when an ink composition is configured.

The hydrophilic group-containing monomer in the present invention is preferably a dissociable group-containing monomer from the viewpoints of self-dispersibility and aggregation, and is a dissociable group-containing monomer having a dissociable group and an ethylenically unsaturated bond. It is preferable.
Examples of the dissociable group-containing monomer include an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.

Specific examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid. Specific examples of the unsaturated sulfonic acid monomer include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, and bis- (3-sulfopropyl) -itaconate. It is done. Specific examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2- Examples include acryloyloxyethyl phosphate.
Among the dissociable group-containing monomers, an unsaturated carboxylic acid monomer is preferable from the viewpoint of dispersion stability and ejection stability, and at least one of acrylic acid and methacrylic acid is more preferable.

Examples of the monomer having a nonionic hydrophilic group include 2-methoxyethyl acrylate, 2- (2-methoxyethoxy) ethyl acrylate, 2- (2-methoxyethoxy) ethyl methacrylate, ethoxytriethylene glycol methacrylate, and methoxypolyethylene. Ethylenically unsaturated monomers containing (poly) ethyleneoxy groups or polypropyleneoxy groups such as glycol (molecular weight 200 to 1000) monomethacrylate, polyethylene glycol (molecular weight 200 to 1000) monomethacrylate, hydroxymethyl (meth) acrylate, 2 -Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate Rate, ethylenically unsaturated monomer having a hydroxyl group such as hydroxymethyl (meth) acrylate.
In addition, as a monomer having a nonionic hydrophilic group, an ethylenically unsaturated monomer having a terminal alkyl ether is more stable in terms of particle stability and content of a water-soluble component than an ethylenically unsaturated monomer having a terminal hydroxyl group. It is preferable from the viewpoint.

As the hydrophilic structural unit in the present invention, an embodiment containing only a hydrophilic unit having an anionic dissociable group, a hydrophilic structural unit having an anionic dissociative group, and a nonionic hydrophilic group It is preferable that it is either of the aspects containing both the hydrophilic structural unit which has.
Also, an embodiment containing two or more hydrophilic units having an anionic dissociable group, a hydrophilic structural unit having an anionic dissociative group, and a hydrophilic structural unit having a nonionic hydrophilic group It is also preferable that two or more are used in combination.

The content of the hydrophilic constituent unit in the self-dispersing polymer is preferably 25% by mass or less, more preferably 1 to 25% by mass, from the viewpoints of the viscosity and the temporal stability of the ink composition. It is more preferable that it is 2-23 mass%, and it is especially preferable that it is 4-20 mass%.
Moreover, when it has 2 or more types of hydrophilic structural units, it is preferable that the total content rate of a hydrophilic structural unit exists in the said range.

The content of the structural unit having an anionic dissociable group in the self-dispersing polymer is preferably in a range where the acid value is in a suitable range described later.
In addition, the content of the structural unit having a nonionic hydrophilic group is preferably 0 to 25% by mass, more preferably 0 to 20% by mass, from the viewpoint of ejection stability and temporal stability. Particularly preferred is 0 to 15% by mass.

The self-dispersing polymer particles in the present invention preferably contain a polymer having a carboxyl group from the viewpoint of self-dispersibility and agglomeration speed when contacted with the treatment liquid, and have a carboxyl group and an acid value (mgKOH / g It is more preferable that the polymer contains 25-100. Furthermore, the acid value is more preferably from 25 to 80, and particularly preferably from 30 to 65, from the viewpoints of self-dispersibility and the aggregation rate when contacted with the treatment liquid.
In particular, when the acid value is 25 or more, the stability of self-dispersibility is good, and when it is 100 or less, the cohesiveness is improved.

The aromatic group-containing monomer is not particularly limited as long as it is a compound containing an aromatic group and a polymerizable group. The aromatic group may be a group derived from an aromatic hydrocarbon or a group derived from an aromatic heterocycle. In the present invention, an aromatic group derived from an aromatic hydrocarbon is preferable from the viewpoint of particle shape stability in an aqueous medium.
The polymerizable group may be a condensation polymerizable polymerizable group or an addition polymerizable polymerizable group. In the present invention, from the viewpoint of particle shape stability in an aqueous medium, an addition polymerizable polymerizable group is preferable, and a group containing an ethylenically unsaturated bond is more preferable.

  The aromatic group-containing monomer in the present invention is preferably a monomer having an aromatic group derived from an aromatic hydrocarbon and an ethylenically unsaturated bond. The aromatic group-containing monomer may be used alone or in combination of two or more.

  Examples of the aromatic group-containing monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, and a styrene monomer. Of these, aromatic group-containing (meth) acrylate monomers are preferred from the viewpoint of the balance between the hydrophilicity and hydrophobicity of the polymer chain and the ink fixability, and include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, and phenyl (meth). At least one selected from acrylates is more preferable, and phenoxyethyl (meth) acrylate and benzyl (meth) acrylate are more preferable.

The self-dispersing polymer particles in the present invention include a structural unit derived from an aromatic group-containing (meth) acrylate monomer, and the content is preferably 10% by mass to 95% by mass. When the content of the structural unit derived from the aromatic group-containing (meth) acrylate monomer is 10% by mass to 95% by mass, the stability of the self-emulsification or dispersion state is improved, and further the increase in ink viscosity is suppressed. be able to.
In the present invention, from the viewpoints of stability in a self-dispersing state, stabilization of particle shape in an aqueous medium due to hydrophobic interaction between aromatic rings, and reduction in the amount of water-soluble components due to appropriate hydrophobicization of particles. More preferably, the content is from mass% to 90 mass%, more preferably from 15 mass% to 80 mass%, and particularly preferably from 25 mass% to 70 mass%.

Further, when using a styrene monomer as the aromatic group-containing monomer, from the viewpoint of stability when making the self-dispersing polymer particles, the structural unit derived from the styrene monomer is preferably 20% by mass or less, The content is more preferably 10% by mass or less, still more preferably 5% by mass or less, and an embodiment that does not include a structural unit derived from a styrene monomer is particularly preferable.
Here, the styrene monomer refers to styrene, substituted styrene (α-methylstyrene, chlorostyrene, etc.), and a styrene macromer having a polystyrene structural unit.

The alicyclic monomer is not particularly limited as long as it is a compound containing an alicyclic hydrocarbon group and a polymerizable group, but is preferably an alicyclic (meth) acrylate from the viewpoint of dispersion stability.
The alicyclic (meth) acrylate includes a structural part derived from (meth) acrylic acid and a structural part derived from alcohol, and the structural part derived from alcohol is unsubstituted or substituted. It has a structure containing at least one hydrocarbon group. The alicyclic hydrocarbon group may be a structural site derived from alcohol itself or may be bonded to a structural site derived from alcohol via a linking group.
The “alicyclic (meth) acrylate” means methacrylate or acrylate having an alicyclic hydrocarbon group.

The alicyclic hydrocarbon group is not particularly limited as long as it contains a cyclic non-aromatic hydrocarbon group, and is a monocyclic hydrocarbon group, a bicyclic hydrocarbon group, a tricyclic or more polycyclic group. A hydrocarbon group is mentioned.
Examples of the alicyclic hydrocarbon group include a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a cycloalkenyl group, a bicyclohexyl group, a norbornyl group, an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, and an adamantyl group. , Decahydronaphthalenyl group, perhydrofluorenyl group, tricyclo [5.2.1.0 ^2,6 ] decanyl group, and bicyclo [4.3.0] nonane.

The alicyclic hydrocarbon group may further have a substituent. Examples of the substituent include alkyl groups, alkenyl groups, aryl groups, aralkyl groups, alkoxy groups, hydroxyl groups, primary amino groups, secondary amino groups, tertiary amino groups, alkyl or arylcarbonyl groups, and cyano groups. Is mentioned.
The alicyclic hydrocarbon group may further form a condensed ring.
As an alicyclic hydrocarbon group in this invention, it is preferable that carbon number of an alicyclic hydrocarbon group part is 5-20 from a viscosity or a soluble viewpoint.

  Examples of the linking group that connects the alicyclic hydrocarbon group and the structural portion derived from alcohol include alkyl groups, alkenyl groups, alkylene groups, aralkyl groups, alkoxy groups, mono- or oligoethylene groups having 1 to 20 carbon atoms. Preferable examples include a cholic group, a mono- or oligopropylene glycol group, and the like.

Specific examples of the alicyclic (meth) acrylate in the present invention are shown below, but the present invention is not limited thereto.
Monocyclic (meth) acrylates include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, and cyclononyl. Examples thereof include cycloalkyl (meth) acrylates having 3 to 10 carbon atoms in the cycloalkyl group such as (meth) acrylate and cyclodecyl (meth) acrylate.
Examples of the bicyclic (meth) acrylate include isobornyl (meth) acrylate and norbornyl (meth) acrylate.
Examples of the tricyclic (meth) acrylate include adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate.
These can be used alone or in admixture of two or more.

  Among these, at least one kind of bicyclic (meth) acrylate or tricyclic or higher polycyclic (meth) acrylate is used from the viewpoints of dispersion stability, fixing property and blocking resistance of the self-dispersing polymer particles. Preferably, it is at least one selected from isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate.

In the present invention, the content of the structural unit derived from the alicyclic (meth) acrylate contained in the self-dispersing polymer particles is based on the stability of the self-dispersing state and the hydrophobic interaction between the alicyclic hydrocarbon groups. From the viewpoint of stabilizing the particle shape in an aqueous medium and reducing the amount of water-soluble components due to appropriate hydrophobicity of the particles, it is preferably 20% by mass or more and 90% by mass or less, and 40% by mass or more and 90% by mass or less. It is more preferable that Particularly preferred is 50 to 80% by mass.
Fixing property and blocking can be improved by setting the structural unit derived from the alicyclic (meth) acrylate to 20% by mass or more. On the other hand, the stability of the polymer particles is improved when the structural unit derived from the alicyclic (meth) acrylate is 90% by mass or less.

The self-dispersing polymer particles in the present invention include, for example, as a hydrophobic structural unit, in addition to a structural unit derived from an aromatic group-containing monomer and a structural unit derived from an alicyclic monomer, A structural unit may be further included.
The monomer that forms the other structural unit (hereinafter sometimes referred to as “other copolymerizable monomer”) can be copolymerized with the hydrophilic group-containing monomer, aromatic group-containing monomer, and alicyclic monomer. If it is a monomer, there will be no restriction | limiting in particular. Among these, an alkyl group-containing monomer is preferable from the viewpoint of flexibility of the polymer skeleton and ease of control of the glass transition temperature (Tg).

  Examples of the alkyl group-containing monomer include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, alkyl (meth) acrylates such as t-butyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate; hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Ethylenically unsaturated monomers having a hydroxyl group such as acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate; Dialkylaminoalkyl (meth) acrylates such as ru (meth) acrylate; N-hydroxyalkyl (meth) such as N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxybutyl (meth) acrylamide Acrylamide; N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N- (n-, iso) butoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-ethoxyethyl (meta And (meth) acrylamides such as N-alkoxyalkyl (meth) acrylamides such as acrylamide and N- (n-, iso) butoxyethyl (meth) acrylamide.

  Among these, (meth) acrylates containing a chain alkyl group having 1 to 8 carbon atoms from the viewpoint of flexibility of the polymer skeleton and ease of control of the glass transition temperature (Tg) and from the viewpoint of dispersion stability of the self-dispersing polymer. Preferably, it is a (meth) acrylate having a chain alkyl group having 1 to 4 carbon atoms, and particularly preferably methyl (meth) acrylate or ethyl (meth) acrylate. Here, the chain alkyl group refers to an alkyl group having a straight chain or a branched chain.

In the present invention, other copolymerizable monomers may be used singly or in combination of two or more.
When the self-dispersing polymer particles contain other constituent units, the content is preferably 10 to 80% by mass, more preferably 15 to 75% by mass, and particularly preferably 20 to 70%. % By mass. When using the monomer which forms another structural unit in combination of 2 or more types, it is preferable that the total content is the said range.

In addition, the self-dispersing polymer in the present invention includes at least one of aromatic group-containing (meth) acrylate and alicyclic (meth) acrylate, other copolymerizable monomers, and hydrophilic group-containing monomers from the viewpoint of dispersion stability. It is also preferable that it is a polymer obtained by polymerizing at least three of the above, and at least one of the aromatic group-containing (meth) acrylate and alicyclic (meth) acrylate, linear or branched chain having 1 to 8 carbon atoms More preferred is a polymer obtained by polymerizing at least three of an alkyl group-containing (meth) acrylate having a hydrophilic group and a hydrophilic group-containing monomer.
In the present invention, from the viewpoint of dispersion stability, the substitution is highly hydrophobic derived from (meth) acrylates having a linear or branched alkyl group having 9 or more carbon atoms, and aromatic group-containing macromonomers. The content of the structural unit having a group is preferably substantially not contained, and more preferably not contained at all.

  The self-dispersing polymer in the present invention may be a random copolymer in which each constitutional unit is irregularly introduced, or a block copolymer in which the structural units are regularly introduced. Each constitutional unit in a certain case may be synthesized in any order of introduction, and the same constitutional component may be used twice or more, but being a random copolymer is versatile and manufacturable. This is preferable.

  The molecular weight range of the self-dispersing polymer in the present invention is preferably 3000 to 200,000, more preferably 5000 to 150,000, and still more preferably 10,000 to 100,000 in terms of weight average molecular weight. In addition, the acid value is 25 to 100 and the weight average molecular weight is preferably 3000 to 200,000, and the acid value is 25 to 95 and the weight average molecular weight is more preferably 5000 to 150,000. . By setting the weight average molecular weight to 3000 or more, the amount of water-soluble components can be effectively suppressed. Moreover, self-dispersion stability can be improved by making a weight average molecular weight into 200,000 or less.

  The weight average molecular weight is measured by gel permeation chromatography (GPC). For GPC, HLC-8020GPC (manufactured by Tosoh Corporation) is used, and TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ200 (4.6 mm ID × 15 cm) manufactured by Tosoh Corporation are used as eluents as columns. Use THF (tetrahydrofuran). As conditions, the sample concentration is 0.35% by mass, the flow rate is 0.35 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and an IR detector is used. In addition, the calibration curve is “standard sample TSK standard, polystyrene” manufactured by Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”, It is prepared from 8 samples of “A-2500”, “A-1000”, “n-propylbenzene”.

The self-dispersing polymer in the invention is a structural unit derived from an aromatic group-containing (meth) acrylate monomer (preferably a structural unit derived from phenoxyethyl (meth) acrylate and / or from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. The structural unit derived from benzyl (meth) acrylate) is 15 to 80% by mass of the total mass of the self-dispersing polymer particles as a copolymerization ratio, the acid value is 25 to 100, and the weight average molecular weight is 3000 to 200,000. It is preferable.
In addition, the self-dispersing polymer has a constitutional unit derived from a carboxyl group-containing monomer having a copolymerization ratio of a structural unit derived from an aromatic group-containing (meth) acrylate monomer from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. And a structural unit derived from an alkyl group-containing monomer (preferably a structural unit derived from an alkyl ester of (meth) acrylic acid), and a structural unit derived from phenoxyethyl (meth) acrylate and / or Alternatively, a structural unit derived from benzyl (meth) acrylate as a copolymerization ratio of 15 to 80% by mass, a structural unit derived from a carboxyl group-containing monomer, and a structural unit derived from an alkyl group-containing monomer (preferably (meth) Structural units derived from alkyl esters of 1 to 4 carbon atoms of acrylic acid) The weight average molecular weight in acid value 25-95 is more preferably 5,000 to 150,000.

  Specific examples of the water-insoluble polymer constituting the resin particles (self-dispersing polymer particles) are listed below as exemplary compounds B-01 to B-36, but the present invention is not limited thereto. In addition, the parenthesis represents the mass ratio of the copolymerization component.

B-01: Phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (50/45/5)
B-02: Phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (30/35/29/6)
B-03: Phenoxyethyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (50/44/6)
B-04: Phenoxyethyl acrylate / methyl methacrylate / ethyl acrylate / acrylic acid copolymer (30/55/10/5)
B-05: benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (35/59/6)
B-06: Styrene / phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (10/50/35/5)
B-07: benzyl acrylate / methyl methacrylate / acrylic acid copolymer (55/40/5)
B-08: Phenoxyethyl methacrylate / benzyl acrylate / methacrylic acid copolymer (45/47/8)
B-09: Styrene / phenoxyethyl acrylate / butyl methacrylate / acrylic acid copolymer (5/48/40/7)
B-10: benzyl methacrylate / isobutyl methacrylate / cyclohexyl methacrylate / methacrylic acid copolymer (35/30/30/5)
B-11: Phenoxyethyl acrylate / methyl methacrylate / butyl acrylate / methacrylic acid copolymer (12/50/30/8)
B-12: benzyl acrylate / isobutyl methacrylate / acrylic acid copolymer (93/2/5)
B-13: Styrene / phenoxyethyl methacrylate / butyl acrylate / acrylic acid copolymer (50/5/20/25)
B-14: Styrene / butyl acrylate / acrylic acid copolymer (62/35/3)
B-15: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/51/4)
B-16: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/49/6)
B-17: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/48/7)
B-18: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/47/8)
B-19: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/45/10)
B-20: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (20/72/8)

B-21: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (30/62/8)
B-22: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (40/52/8)
B-23: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (50/42/8)
B-24: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (38/52/10)
B-25: Methyl methacrylate / isobornyl methacrylate / benzyl methacrylate / methacrylic acid copolymer (30/50/14/6)
B-26: Methyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (40/50/10)
B-27: Methyl methacrylate / dicyclopentanyl methacrylate / phenoxyethyl methacrylate / methacrylic acid copolymer (30/50/14/6)
B-28: Methyl methacrylate / isobornyl methacrylate / methoxypolyethylene glycol methacrylate (n = 2) / methacrylic acid copolymer (30/54/10/6)
B-29: Methyl methacrylate / dicyclopentanyl methacrylate / methoxypolyethylene glycol methacrylate (n = 2) / methacrylic acid copolymer (54/35/5/6)
B-30: Methyl methacrylate / adamantyl methacrylate / methoxy polyethylene glycol methacrylate (n = 23) / methacrylic acid copolymer (30/50/15/5)
B-31: Methyl methacrylate / isobornyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (20/50/22/8)
B-32: Ethyl methacrylate / cyclohexyl methacrylate / acrylic acid copolymer (50/45/5)
B-33: Isobutyl methacrylate / cyclohexyl methacrylate / acrylic acid copolymer (40/50/10)
B-34: n-butyl methacrylate / cyclohexyl methacrylate / styrene / acrylic acid copolymer (30/55/10/5)
B-35: Methyl methacrylate / dicyclopentenyloxyethyl methacrylate / methacrylic acid copolymer (40/52/8)
B-36: Lauryl methacrylate / dicyclopentenyloxyethyl methacrylate / methacrylic acid copolymer (25/65/10)

In addition, the self-dispersing polymer of the present invention is a dissociable group-containing monomer having a structure derived from an alicyclic (meth) acrylate having a copolymerization ratio of 20% by mass to 90% by mass from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. And a structure derived from (meth) acrylate containing a chain alkyl group having 1 to 8 carbon atoms, an acid value of 20 to 120, and a hydrophilic structural unit A vinyl polymer having a total content of 25% by mass or less and a weight average molecular weight of 3000 to 200,000 is also preferable.
Furthermore, it contains a chain alkyl group having 1 to 4 carbon atoms and a structure derived from a bicyclic or tricyclic or higher polycyclic (meth) acrylate as a copolymerization ratio of 30% by mass or more and less than 90% by mass. A structure derived from (meth) acrylate as a copolymerization ratio is 10% by mass or more and less than 70% by mass, and a structure derived from a carboxyl group-containing monomer has an acid value in the range of 25 to 100, and the total content of hydrophilic structural units A vinyl polymer having a rate of 25% by mass or less and a weight average molecular weight of 10,000 to 200,000 is more preferable.
Furthermore, a structure derived from a bicyclic or tricyclic or higher polycyclic (meth) acrylate having a copolymerization ratio of 40% by mass or more and less than 80% by mass, at least methyl (meth) acrylate or ethyl (meth) acrylate Containing the derived structure as a copolymerization ratio of 20% by mass or more and less than 60% by mass, including the structure derived from acrylic acid or methacrylic acid in an acid value range of 30 to 80, and the total content of hydrophilic structural units being 25% by mass %, And a vinyl polymer having a weight average molecular weight of 30,000 to 150,000 is particularly preferable.

  The method for producing the water-insoluble polymer constituting the resin particles in the present invention is not particularly limited. For example, emulsion polymerization is carried out in the presence of a polymerizable surfactant to covalently bond the surfactant and the water-insoluble polymer. Examples thereof include a method of copolymerizing a monomer mixture containing the hydrophilic group-containing monomer and the aromatic group-containing monomer by a known polymerization method such as a solution polymerization method or a bulk polymerization method. Among the polymerization methods, a solution polymerization method is preferable and a solution polymerization method using an organic solvent is more preferable from the viewpoint of aggregation rate and droplet ejection stability when an ink composition is used.

  The self-dispersing polymer particles in the present invention include a polymer synthesized in an organic solvent from the viewpoint of aggregation rate, and the polymer has a carboxyl group (preferably having an acid value of 20 to 100). Part or all of the carboxyl groups of the polymer are preferably neutralized and prepared as a polymer dispersion having water as a continuous phase. That is, the production of the self-dispersing polymer particles in the present invention includes a step of synthesizing a polymer in an organic solvent and a dispersion step of making an aqueous dispersion in which at least a part of the carboxyl groups of the polymer is neutralized. It is preferable to do so.

The dispersion step preferably includes the following step (1) and step (2).
Step (1): Step of stirring a mixture containing a polymer (water-insoluble polymer), an organic solvent, a neutralizing agent, and an aqueous medium Step (2): Step of removing the organic solvent from the mixture

The step (1) is preferably a treatment in which a polymer (water-insoluble polymer) is first dissolved in an organic solvent, then a neutralizing agent and an aqueous medium are gradually added, mixed and stirred to obtain a dispersion. In this way, by adding a neutralizing agent and an aqueous medium to a water-insoluble polymer solution dissolved in an organic solvent, a self-dispersing polymer having a particle size with higher storage stability without requiring strong shearing force. Particles can be obtained.
There is no restriction | limiting in particular in the stirring method of this mixture, Dispersers, such as a generally used mixing stirring apparatus and an ultrasonic disperser, a high-pressure homogenizer, can be used as needed.

Preferred examples of the organic solvent include alcohol solvents, ketone solvents, and ether solvents.
Examples of the alcohol solvent include isopropyl alcohol, n-butanol, t-butanol, ethanol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of ether solvents include dibutyl ether and dioxane. Among these solvents, ketone solvents such as methyl ethyl ketone and alcohol solvents such as isopropyl alcohol are preferable. It is also preferable to use isopropyl alcohol and methyl ethyl ketone in combination for the purpose of moderating the polarity change during the phase inversion from oil to water. By using this solvent in combination, it is possible to obtain self-dispersing polymer particles having a fine particle size with high dispersion stability without aggregation and sedimentation and fusion between particles.

  The neutralizing agent is used so that a part or all of the dissociable group is neutralized and the self-dispersing polymer forms a stable emulsified or dispersed state in water. When the self-dispersing polymer of the present invention has an anionic dissociative group (for example, a carboxyl group) as a dissociable group, the neutralizing agent used is basic such as an organic amine compound, ammonia, or an alkali metal hydroxide. Compounds. Examples of organic amine compounds include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, monoethanolamine, diethanolamine, triethanolamine, N, N-dimethyl-ethanolamine, N, N-diethyl-ethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, N-methyldiethanolamine, N-ethyldiethanolamine, monoisopropanolamine, diisopropanol Examples include amines and triisopropanolamine. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Among these, sodium hydroxide, potassium hydroxide, triethylamine, and triethanolamine are preferable from the viewpoint of stabilizing the dispersion of the self-dispersing polymer particles of the present invention in water.

  These basic compounds are preferably used in an amount of 5 to 120 mol%, more preferably 10 to 110 mol%, still more preferably 15 to 100 mol%, based on 100 mol% of the dissociable group. . By setting it as 15 mol% or more, the effect which stabilizes dispersion | distribution of the particle | grains in water expresses, and there exists an effect which reduces a water-soluble component by setting it as 100 mol% or less.

  In the step (2), the aqueous dispersion of the self-dispersing polymer particles is obtained by distilling off the organic solvent from the dispersion obtained in the step (1) by a conventional method such as distillation under reduced pressure and phase-inversion into an aqueous system. A dispersion can be obtained. The organic solvent in the obtained aqueous dispersion has been substantially removed, and the amount of the organic solvent is preferably 0.2% by mass or less, more preferably 0.1% by mass or less.

The average particle diameter of the resin particles is preferably in the range of 10 nm to 1 μm in terms of volume average particle diameter, more preferably in the range of 10 to 200 nm, still more preferably in the range of 10 to 100 nm, and particularly preferably in the range of 10 to 50 nm. When the volume average particle diameter is 10 nm or more, the production suitability is improved, and when it is 1 μm or less, the storage stability is improved.
Moreover, there is no restriction | limiting in particular regarding the particle size distribution of a resin particle, Any of what has a wide particle size distribution or a monodispersed particle size distribution may be sufficient. Two or more kinds of resin particles having a monodispersed particle size distribution may be mixed.
The average particle size and particle size distribution of the resin particles are determined by a dynamic light scattering method using a nanotrack particle size distribution measuring device UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

The resin particles (particularly self-dispersing polymer particles) can be used alone or in combination of two or more.
The content of the resin particles in the ink composition is preferably 0.5 to 20% by mass, more preferably 2 to 20% by mass, and further preferably 3 to 15% by mass with respect to the total mass of the ink composition.

(Surfactant)
The ink composition of the present invention may contain a surfactant as necessary. The surfactant can be used as a surface tension adjusting agent.
As a surface tension modifier, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactant, cationic surfactant, amphoteric surfactant, nonionic surfactant Either a 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 inkjet 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 antifading agent, various organic and metal complex antifading 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.

  Examples of solid wetting agents include glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and other sugars; sugar alcohols; hyaluronic acids; urea And the like.

~ Physical properties of ink composition ~
The surface tension (25 ° C.) of the ink composition of the present invention is preferably 20 mN / m or more and 60 mN / m or less. 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 using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) under the condition of 25 ° C.

The viscosity at 25 ° C. of the ink composition of the present 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 still more 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.

<Image forming method>
Hereinafter, the image forming method of the present invention will be described in detail.
The image forming method of the present invention uses the ink set of the present invention to apply a treatment liquid that includes (i) a treatment liquid containing an acid generator that aggregates the components in the ink composition and a flocculant on the recording medium. And (ii) an ink application step of applying an ink composition containing a colorant, preferably a water-soluble organic solvent and water, to form an image on a recording medium.
In addition, the image forming method of the present invention includes an ink drying step for drying and removing the organic solvent in the ink composition applied to the coated paper, if necessary, and a resin particle or polymer contained in the ink composition. Another process such as a heat fixing process for melting and fixing the latex may be further provided.

In the present invention, the recording medium is preferably a coated paper. That is, an ink composition containing a colorant and an acid generator and an aggregating agent that are aggregating components for aggregating the components in the ink composition on a coated paper typified by art paper or coated paper as a recording medium. It is preferable to form an image using a processing solution containing a specific amount.
Considering that the processing solution contains an acid generator and an aggregating agent at the time of image formation, the amount of the processing solution is selected and applied to efficiently use the agglomeration reaction and quickly fix the image. Can be done.
Therefore, the surface of the paper such as rough surface does not change and the final image surface is not damaged, and fine lines and fine image parts can be drawn finely and uniformly, and when an ink composition is applied over a wide range such as solid recording In addition to suppressing the occurrence of unevenness, an image having high density uniformity is obtained, and the abrasion resistance (adhesion to paper) and offset resistance of the image are also improved. Further, high-density image formation is possible, and the color reproducibility of the image is also improved.

  In the image forming method of the present invention, either the treatment liquid application step or the ink application step may be performed in advance. Image quality and abrasion resistance by drawing fine lines and fine image parts more precisely and homogeneously, or by reducing unevenness when applying ink over a wide range such as solid recording and improving density uniformity as much as possible. From the viewpoint of further improving the offset resistance, a mode in which an image is formed by applying an ink composition in the ink application step after applying the treatment liquid on the recording medium in the treatment liquid application step is preferable. When the treatment liquid is applied onto the recording medium, it can be applied to a part of the paper or the entire surface of the paper, but it is preferably applied to the entire surface of the paper.

[Processing liquid application process]
In the treatment liquid application step of the present invention, a treatment liquid containing an aggregating agent and an acid generator, which are components for aggregating (also referred to as “immobilizing”) the components in the ink composition of the present invention, is applied to the coated paper. . By configuring the image recording method to form an image using an ink composition in the presence of a treatment liquid, it is possible to obtain curl and cockle after recording, and to suppress the occurrence of ink repellency, image quality, and abrasion resistance. In addition, an image having good offset resistance can be recorded.

  For applying the treatment liquid onto the recording medium, a known liquid application method can be used without particular limitation, and any method such as spray application, application using an application roller, application by an inkjet method, immersion, etc. can be selected. it can.

  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 size press method represented by an air knife coater method, etc .; Knife coater method; transfer roll coater method such as gate roll coater method, direct roll coater method, reverse roll coater method, roll coater method represented by squeeze roll coater method; bill blade coater method, short duel coater method; Blade coater method typified by stream coater method, etc .; Bar coater method typified by rod bar coater method, etc .; Bar coater method typified by rod bar coater method, etc .; Cast coater method; Gravure coater method; Coater method; die coater method; brush coater method; and the like transfer method.

  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.

Although there is no restriction | limiting in particular as an application quantity of the processing liquid in a processing liquid provision process, For example, it can be set to 0.01-5 g / m < ² >, and it is 0.1-4. From a viewpoint of offset resistance and image quality. preferably a 5 g / ^{m 2,} and more preferably 0.2~4.0g / ^{m 2.}

[Ink application process]
In the ink application step in the present invention, an ink composition containing a colorant is applied onto a recording medium to form an image.
The ink composition has the same meaning as that described in the section of the ink composition in the ink set of the present invention, and preferred examples thereof are also the same.
The ink application process is not particularly limited as long as an image can be recorded by applying the ink composition onto a recording medium by an ink jet method. In the image formation by the 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 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.

[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.

[Immobilization process]
The ink jet recording method of the present invention preferably further comprises an immobilization step of immobilizing the image recorded in the ink application step on the recording medium after the treatment liquid application step. The fixing step is preferably a heat and pressure fixing step for melting and fixing resin particles that may be contained in the ink composition. The heat and pressure fixing step is not particularly limited as long as it is a method capable of melting and fixing the resin particles contained in the ink composition, and can be appropriately selected according to the purpose.
For example, the heat and pressure fixing process described in Japanese Patent Application Laid-Open No. 2004-174981 can be applied to the present invention.

[recoding media]
In the image forming method of the present invention, as described above, it is preferable to use so-called coated paper used for general offset printing or the like as the recording medium. 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.

  These general printing papers cause quality problems such as image bleeding and abrasion resistance in the image formation by the ink jet method using a normal water-based ink, but the ink jet image forming method in the image forming method of the present invention. In this case, image blurring is suppressed to prevent occurrence of uneven density, and an image having good abrasion resistance and offset resistance can be recorded.

  The coated paper can be obtained and used on the market. For example, coated paper for general printing can be used. Specifically, coated paper such as “OK Top Coat +” manufactured by Oji Paper Co., “Aurora Coat” manufactured by Nippon Paper Industries Co., Ltd., “Ulite”, etc. (A2 B2), and art paper (A1) such as “Tokuhishi Art” manufactured by Mitsubishi Paper Industries.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. 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 tube, 88 g of methyl ethyl ketone was added and heated to 72 ° C. in a nitrogen atmosphere. Here, 50 g of methyl ethyl ketone was mixed with 0.85 g of dimethyl 2,2′-azobisisobutyrate and 60 g of benzyl methacrylate. 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 resin was diluted to 0.1% with tetrahydrofuran and calculated in terms of polystyrene by GPC ((gel permeation chromatography). The weight average molecular weight (Mw) calculated | required from TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ200 (made by Tosoh Corporation) 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-
Pigment Blue 15: 3 (phthalocyanine blue A220, manufactured by Dainichi Seika Kogyo Co., Ltd.), 5 parts of polymer dispersant P-1, 42 parts of methyl ethyl ketone, 5.5 parts of 1 mol / L NaOH aqueous solution, Then, 87.2 parts of ion-exchanged water was mixed and dispersed with a bead mill using 0.1 mmφ zirconia beads for 2 to 6 hours.
Methyl ethyl ketone was removed from the obtained dispersion under reduced pressure at 55 ° C., and a part of water was further removed, whereby a resin-coated cyan pigment (encapsulated pigment) dispersion (color) having a pigment concentration of 10.2% by mass was obtained. Material).

-Resin-coated magenta pigment dispersion-
In the preparation of the above-mentioned resin-coated cyan pigment dispersion, the resin coating was carried out in the same manner as above except that Chromathal Jet Magenta DMQ (Pigment Red 122, manufactured by Ciba Japan) was used instead of phthalocyanine blue A220 used as the pigment. A magenta pigment dispersion (coloring material) was obtained.

-Resin-coated yellow pigment dispersion-
Resin-coated yellow was prepared in the same manner as described above except that Irgalite Yellow GS (Pigment Yellow 74, manufactured by Ciba Japan) was used instead of phthalocyanine blue A220 used as a pigment in the preparation of the resin-coated cyan pigment dispersion. A pigment dispersion (coloring material) was obtained.

-Resin-coated black pigment dispersion-
In the preparation of the resin-coated cyan pigment dispersion, a resin was obtained in the same manner as above except that the pigment dispersion CAB-O-JETTM 200 (carbon black, manufactured by CABOT) was used instead of the phthalocyanine blue A220 used as the pigment. A coated black pigment dispersion (coloring material) was obtained.

(Preparation of self-dispersing polymer particles)
-Synthesis of self-dispersing polymer particles B-20-
In a 2 liter three-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 540.0 g of methyl ethyl ketone was charged, and the temperature was raised to 75 ° C. in a nitrogen atmosphere. 1. While maintaining the temperature in the reaction vessel at 75 ° C., 108 g of methyl methacrylate, 388.8 g of isobornyl methacrylate, 43.2 g of methacrylic acid, 108 g of methyl ethyl ketone, and “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) The mixed solution consisting of 16 g was added dropwise at a constant speed so that the addition was completed in 2 hours. After completion of the dropwise addition, a solution consisting of 1.08 g of “V-601” and 15.0 g of methyl ethyl ketone was added, stirred for 2 hours at 75 ° C., and then a solution consisting of 0.54 g of “V-601” and 15.0 g of methyl ethyl ketone was added. After stirring at 75 ° C. for 2 hours, the temperature was raised to 85 ° C., and stirring was further continued for 2 hours.
The weight average molecular weight (Mw) of the obtained copolymer was 61000 (calculated in terms of polystyrene by gel permeation chromatography (GPC), the columns used were TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ200 (manufactured by Tosoh Corporation)), The acid value was 52.1 (mgKOH / g).
In addition, the monomer composition (mass basis) of B-20 is methyl methacrylate / isobornyl methacrylate / methacrylic acid (20/72/8).

  Next, 588.2 g of the polymerization solution was weighed, 165 g of isopropanol and 120.8 ml of 1 mol / L NaOH aqueous solution were added, and the temperature in the reaction vessel was raised to 80 ° C. Next, 718 g of distilled water was added dropwise at a rate of 20 ml / min to disperse in water. Then, the solvent was distilled off by keeping the temperature in the reaction vessel at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure. Furthermore, the pressure in the reaction vessel was reduced, and isopropanol, methyl ethyl ketone, and distilled water were distilled off to obtain an aqueous dispersion of self-dispersing polymer particles B-20 (resin particles) having a solid content concentration of 26.0%.

  Self-dispersing polymer particles (resin particles) having the following monomer composition in the same manner as described above, except that in the preparation of the aqueous dispersion of the self-dispersing polymer particles B-20, the type and amount of the monomer were changed. Aqueous dispersions of each were prepared. The values in parentheses represent the mass ratio of the copolymer component.

B-22: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (40/52/8)
B-24: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (38/52/10)

[Preparation of ink set 1]
As described below, cyan ink (C-1), magenta ink (M-1), yellow ink (Y-1), and black ink (K-1) were prepared, and these ink compositions were used. Ink set 1 was prepared.

(Preparation of cyan ink C-1)
Using the above resin-coated cyan pigment dispersion and the aqueous dispersion of self-dispersing polymer B-20, a water-soluble organic solvent, a surfactant, and ion-exchanged water are mixed so as to have the following composition, and then 5 μm. Cyan ink was prepared by filtration through a membrane filter.

-Composition of cyan ink C-1-
・ Cyan pigment (Pigment Blue 15: 3) ・ ・ ・ 4%
・ Polymer dispersant P-1 (solid content) 2%
・ Self-dispersing polymer particles B-20 (resin particles, solid content) 6%
・ POP (3) glyceryl ether (GP-250, water-soluble organic solvent)
... 8%
・ Tripropylene glycol monomethyl ether (TPGmME, water-soluble organic solvent)
... 8%
・ Olfin E1010 ・ ・ ・ 1%
(Nissin Chemical Industry Co., Ltd .; surfactant)
・ Ion-exchanged water: Added to 100% overall.

  When the pH (25 ° C.) of cyan ink C-1 was measured using a pH meter WM-50EG (manufactured by Toa DKK), the pH value was 8.5.

(Preparation of magenta ink M-1)
Magenta ink M-1 was prepared in the same manner as described above except that a resin-coated magenta pigment dispersion was used instead of the resin-coated cyan pigment dispersion in the preparation of the cyan ink C-1. The pH value was 8.5.

-Composition of magenta ink M-1-
・ Magenta pigment (Pigment Red 122) 4%
・ Polymer dispersant P-1 (solid content) 2%
・ Self-dispersing polymer particles B-20 (resin particles, solid content) 6%
・ POP (3) glyceryl ether (GP-250, water-soluble organic solvent)
... 8%
・ Tripropylene glycol monomethyl ether (TPGmME, water-soluble organic solvent)
... 8%
・ Olfin E1010 ・ ・ ・ 1%
(Nissin Chemical Industry Co., Ltd .; surfactant)
・ Ion-exchanged water: Added to 100% overall.

(Preparation of yellow ink Y-1)
A yellow ink Y-1 was prepared in the same manner as in the preparation of the cyan ink C-1, except that a resin-coated yellow pigment dispersion was used instead of the resin-coated cyan pigment dispersion. The pH value was 8.5.

-Composition of yellow ink Y-1-
・ Yellow pigment (Pigment Yellow 74) ・ ・ ・ 4%
・ Polymer dispersant P-1 (solid content) 2%
・ Self-dispersing polymer particles B-20 (resin particles, solid content) 6%
・ POP (3) glyceryl ether (GP-250, water-soluble organic solvent)
... 8%
・ Tripropylene glycol monomethyl ether (TPGmME, water-soluble organic solvent)
... 8%
・ Olfin E1010 ・ ・ ・ 1%
(Nissin Chemical Industry Co., Ltd .; surfactant)
・ Ion-exchanged water: Added to 100% overall.

(Preparation of black ink K-1)
Black ink K-1 was prepared in the same manner as described above except that a resin-coated black pigment dispersion was used instead of the resin-coated cyan pigment dispersion in the preparation of the cyan ink C-1.

-Composition of black ink K-1-
・ Black pigment (carbon black) ・ ・ ・ 4%
・ Polymer dispersant P-1 (solid content) 2%
・ Self-dispersing polymer particles B-20 (resin particles, solid content) 6%
・ POP (3) glyceryl ether (GP-250, water-soluble organic solvent)
... 8%
・ Tripropylene glycol monomethyl ether (TPGmME, water-soluble organic solvent)
... 8%
・ Olfin E1010 ・ ・ ・ 1%
(Nissin Chemical Industry Co., Ltd .; surfactant)
・ Ion-exchanged water: Added to 100% overall.

[Preparation of ink sets 2-3]
The ink set 1 was prepared except that the ink set 2 was changed to the self-dispersing polymer B-22 and the ink set 3 was changed to the self-dispersing polymer B-24. Ink sets 2 to 3 were prepared in the same manner as in Example 1.

(Preparation of treatment liquid 1)
The following components were mixed to prepare treatment liquid 1. It was 1.21 when pH (25 degreeC) of the processing liquid 1 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
-Imidosulfonate (AG-1): 3.0 g
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 2)
The following components were mixed to prepare treatment liquid 2. It was 1.21 when pH (25 degreeC) of the processing liquid 2 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Imidosulfonate (AG-1, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 3)
The following components were mixed to prepare treatment liquid 3. It was 1.25 when pH (25 degreeC) of the processing liquid 3 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Imidosulfonate (AG-2, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 4)
The following components were mixed to prepare a treatment liquid 4. It was 1.25 when pH (25 degreeC) of the processing liquid 4 was measured with the Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Imidosulfonate (AG-2, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 5)
The following components were mixed to prepare a treatment liquid 5. It was 1.25 when pH (25 degreeC) of the processing liquid 5 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Imidosulfonate (AG-3, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 6)
The processing liquid 6 was produced by mixing the following components. It was 1.25 when pH (25 degreeC) of the processing liquid 6 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Imidosulfonate (AG-3, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 7)
The following components were mixed to prepare a treatment liquid 7. It was 1.25 when pH (25 degreeC) of the processing liquid 7 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Imidosulfonate (AG-4, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 8)
The following components were mixed to prepare a treatment liquid 8. It was 1.25 when pH (25 degreeC) of the processing liquid 8 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Imidosulfonate (AG-4, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 9)
The processing liquid 9 was produced by mixing the following components. It was 1.12 when pH (25 degreeC) of the processing liquid 9 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Oxime sulfonate (AG-5, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 10)
The processing liquid 10 was produced by mixing the following components. It was 1.12 when pH (25 degreeC) of the processing liquid 10 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Oxime sulfonate (AG-5, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 11)
The processing liquid 11 was produced by mixing the following components. It was 1.21 when pH (25 degreeC) of the processing liquid 11 was measured with the Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Oxime sulfonate (AG-6, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 12)
The following components were mixed to prepare a treatment liquid 12. It was 1.21 when pH (25 degreeC) of the processing liquid 12 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
・ Oxime sulfonate (AG-6, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 13)
The following components were mixed to prepare a treatment liquid 13. It was 1.12 when pH (25 degreeC) of the processing liquid 13 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Oxime sulfonate (AG-7, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 14)
The following components were mixed to prepare a treatment liquid 14. It was 1.12 when pH (25 degreeC) of the processing liquid 14 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Oxime sulfonate (AG-7, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 15)
The processing liquid 15 was produced by mixing the following components. It was 1.21 when pH (25 degreeC) of the processing liquid 15 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Oxime sulfonate (AG-8, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 16)
The processing liquid 16 was produced by mixing the following components. It was 1.21 when pH (25 degreeC) of the processing liquid 16 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
・ Oxime sulfonate (AG-8, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 17)
The following components were mixed to prepare a treatment liquid 17. It was 0.95 when pH (25 degreeC) of the processing liquid 17 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Nitrobenzyl sulfonate (AG-9, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 18)
The following components were mixed to prepare a treatment liquid 18. It was 0.95 when pH (25 degreeC) of the processing liquid 18 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Nitrobenzyl sulfonate (AG-9, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 19)
The following components were mixed to prepare a treatment liquid 19. It was 1.15 when pH (25 degreeC) of the processing liquid 19 was measured with the pH meter WM-50EG by Toa DKK Co., Ltd.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Nitrobenzyl sulfonate (AG-10, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 20)
The processing liquid 20 was produced by mixing the following components. It was 1.15 when pH (25 degreeC) of the processing liquid 20 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Nitrobenzyl sulfonate (AG-10, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 21)
The processing liquid 21 was produced by mixing the following components. It was 1.15 when pH (25 degreeC) of the processing liquid 21 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Nitrobenzyl sulfonate (AG-11, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 22)
The following components were mixed to prepare a treatment liquid 22. It was 1.15 when pH (25 degreeC) of the processing liquid 22 was measured with the Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Nitrobenzyl sulfonate (AG-11, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 23)
The processing liquid 23 was produced by mixing the following components. It was 1.21 when pH (25 degreeC) of the processing liquid 23 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Sulfonate compound (AG-12, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 24)
The processing liquid 24 was produced by mixing the following components. It was 1.21 when pH (25 degreeC) of the processing liquid 24 was measured with Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Sulfonate compound (AG-12, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 25)
The processing liquid 25 was produced by mixing the following components. It was 1.25 when pH (25 degreeC) of the processing liquid 25 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Sulfonate compound (AG-13, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 26)
The following components were mixed to prepare a treatment liquid 26. It was 1.25 when pH (25 degreeC) of the processing liquid 26 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Sulfonate compound (AG-13, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 27)
The following components were mixed to prepare a treatment liquid 27. It was 1.12 when pH (25 degreeC) of the process liquid 27 was measured with the Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Sulfonate compound (AG-14, acid generator): 3.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 64.3%

(Preparation of treatment liquid 28)
The processing liquid 28 was produced by mixing the following components. It was 1.12 when pH (25 degreeC) of the processing liquid 28 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
Sulfonate compound (AG-14, acid generator): 5.0%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

(Preparation of treatment liquid 29)
The following components were mixed to prepare a treatment liquid 29. It was 1.00 when pH (25 degreeC) of the processing liquid 29 was measured with Toa DKK Co., Ltd. product pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 22.5%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 67.3%

(Preparation of treatment liquid 30)
The processing liquid 30 was produced by mixing the following components. It was 1.00 when pH (25 degreeC) of the processing liquid 30 was measured with the Toa DKK Co., Ltd. pH meter WM-50EG.
-Treatment liquid composition-
Malonic acid (flocculant (acidic substance)): 27.5%
・ GP-250: 10%
Surfactant A (10%): 0.2%
・ Ion exchange water: 62.3%

The structure of surfactant A used in the treatment liquid and the acid generator are shown below.
Surfactant A:
_{C 7 H 15 -CH = CH-} C 7 H 14 -C (= O) -N (CH 3) -CH 2 CH 2 -SO 3 Na

<Example 1>
[Inkjet recording]
As recording media (coated paper), Tokuhishi Art (basis weight 104.7 g / m ² , manufactured by Mitsubishi Paper Industries), OK Top Coat + (basis weight 104.7 g / m ² , manufactured by Oji Paper Co., Ltd.) ) And a silver diamond (basis weight 104.7 g / m ² , manufactured by Nippon Paper Industries Co., Ltd.), an image was formed as shown below, and the following evaluation was performed on the formed image. The results are shown in Table 1.

As the ink composition, an ink set composed of the cyan ink, magenta ink, yellow ink, and black ink obtained above was used, and a line image and a solid image were formed by four-color single pass recording together with the treatment liquid 1.
At this time, a line image was formed by ejecting a 1200-dot line of 1 dot width, a 2-dot width line, and a 4-dot width line in a single pass in the main scanning direction.
The solid image was formed by discharging the ink composition over the entire surface of a sample obtained by cutting the recording medium into A5 size. The conditions for recording are as follows.

(1) Treatment liquid application process The entire surface of the recording medium is processed with a roll coater whose application amount is controlled by an anilox roller (number of lines: 100 to 300 / inch) so that the application amount is 1.4 g / m ^2. The liquid was applied.

(2) Processing Step Next, a drying treatment and a permeation treatment were performed on the recording medium coated with the treatment liquid under the following conditions.
・ Wind speed: 10m / s
-Temperature: Heated by a contact type flat heater from the opposite side (back side) of the recording surface of the recording medium so that the surface temperature of the recording surface of the recording medium was 60 ° C.

(3) Ink application step Thereafter, the ink composition was ejected by an inkjet method on the application surface of the recording medium coated with the treatment liquid under the following conditions to form a line image and a solid image, respectively.
・ Head: 1,200 dpi / 20 inch wide piezo full line head for 4 colors ・ Discharged droplet volume: 2.0 pL
・ Drive frequency: 30kHz

(4) Ink drying step Next, the recording medium provided with the ink composition was dried under the following conditions.
・ Drying method: blow drying ・ wind speed: 15m / s
-Temperature: Heated by a contact type flat heater from the opposite side (back side) of the recording surface of the recording medium so that the surface temperature of the recording surface of the recording medium was 60 ° C.

(5) Fixing step Next, a heat fixing process was performed by passing a roller pair under the following conditions.
・ Silicon rubber roller (hardness 50 °, nip width 5mm)
・ Roller temperature: 70 ℃
・ Pressure: 0.2 MPa

[Evaluation]
-Abrasion resistance-
Immediately after printing a 2 cm square solid portion of a recording medium on which a solid image was recorded, a recording medium that was not recorded (the same recording medium used for recording (hereinafter referred to as an unused sample in this evaluation)) was superimposed. The load was 150 kg / m ² and rubbed back and forth 10 times, and the degree of ink transfer to the white background of the unused sample was visually observed and evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: There was no transfer of ink.
B: Slight ink transfer was observed, but it was at a level where there was no practical problem.
C: Some transfer of ink was observed, which was a practically acceptable limit level.
D: Ink transfer was remarkable and the level of practicality was extremely low.

−Offset resistance−
When a solid image was formed with cyan ink on a solid image with magenta ink, the uniform image portion was visually observed, and the degree of density unevenness was evaluated according to the following evaluation criteria.
~Evaluation criteria~
A: No offset was seen.
B: A slight offset was observed in part, but it was at a level causing no practical problem.
C: An offset occurred and was a practically acceptable limit level.
D: The occurrence of offset was remarkable and the level of practicality was extremely low.

<Examples 2 to 69>
In Example 1, except that the recording medium and ink set to be used, and the type and application amount of the treatment liquid were changed as shown in Tables 1 and 2, image formation by the inkjet method was performed in the same manner as in Example 1, and the same Was evaluated. The results are shown in Tables 1 and 2.

<Comparative Examples 1-9>
In Example 1, except that the recording medium and ink set to be used and the treatment liquid were changed as shown in Table 2, image formation by an inkjet method was performed in the same manner as in Example 1, and evaluation was performed in the same manner. The results are shown in Table 2.

As shown in Tables 1 and 2, in the examples having the configuration of the present invention, when coated paper is used, a line image having a uniform width is obtained. Occurrence was suppressed, and a uniform and high density image could be obtained. In addition, image variation due to offset was suppressed, the gloss of the entire image was good, and the abrasion resistance was also good.
On the other hand, in the comparative example using no flocculant, the density unevenness and the line image drawing performance were inferior, and the image scratch resistance and offset resistance were also poor.

Claims (14)

  An ink set comprising: an ink composition containing a colorant; and a treatment liquid containing an acid generator and a flocculant.   The ink set according to claim 1, wherein the ink composition further comprises a water-soluble organic solvent and water.   The ink set according to claim 1, wherein the acid generator generates an acid by at least one of light and heat.   The ink set according to any one of claims 1 to 3, wherein the acid generator is at least one selected from imide sulfonate, oxime sulfonate, and nitrobenzyl sulfonate.   The ink set according to claim 1, wherein the flocculant is at least one selected from an acidic substance and a polyvalent metal salt. The ink according to claim 4 or 5, wherein the acid generator is at least one selected from the following general formula (I), general formula (II), general formula (III), and general formula (IV). set.


(In General Formula (I), C ₁ (carbon atom) and C ₂ (carbon atom) are bonded by a single bond or a double bond, and R ₁ or R ₂ may be the same or different, and the following (1 ) To any one of (4).
(1) A hydrogen atom, an alkyl group, a cycloalkyl group, and an aryl group each independently.
(2) A group that forms a monocyclic or polycyclic ring that may contain one or more heteroatoms together with C ₁ and C ₂ .
(3) A group forming a condensed aromatic ring containing C ₁ and C ₂ .
(4) A residue containing N-sulfonyloxyimide.
R ₃ represents an alkyl group, a halogenated alkyl group, a cyclic alkyl group, an alkenyl group, an aryl group which may have a substituent, an aralkyl group which may have a substituent, or a camphor group.
In general formula (II), R ₄ and R _{5 each} have an optionally substituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group, cycloalkenyl group, or substituent group having 1 to 16 carbon atoms. Represents an aryl group, a heteroaryl group, or a cyano group. R ₄ and R ₅ are each independently an alkylene chain having 2 to 8 carbon atoms which may have a substituent, an alkenylene chain, an alkynylline chain, or phenylene which may have a substituent, It is bonded to R ₄ or R _{5 of} another compound represented by the general formula (II) via a linking chain containing freelen, thienylene, —O—, —S—, —N—, —CO—. Also good.
R ₆ represents an optionally substituted alkyl group having 1 to 16 carbon atoms, a cycloalkyl group, and an optionally substituted aryl group.
In general formula (III), Z represents an alkyl group, an aryl group, an alkylaryl group, a halogen-substituted alkyl group, a halogen-substituted aryl group, a halogen-substituted alkylaryl group, a nitro-substituted aryl group, nitro A substituted alkylaryl group, an aryl group having a nitro substituent and a halogen substituent, an alkylaryl group having a nitro substituent and a halogen substituent, or a formula —C ₆ H ₄ SO ₃ CHR′C ₆ H _4-m Represents a group having Q _m (NO ₂ ); R ′ represents a hydrogen atom, a methyl group, or a nitro-substituted aryl group. m represents 0, 1 or 2, and when m is 1 or 2, each Q independently represents a hydrocarbon group, a hydrocarbonoxy group, a nitro group, a halogen atom or an organosilicon group. However, Q is not an acidic group. R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an acyl group having 1 to 4 carbon atoms.
In general formula (IV), R ′ and R ″ may each independently have a linear or branched or cyclic alkyl group having 1 to 10 carbon atoms which may have a substituent, or may have a substituent. A good aryl group having 6 to 20 carbon atoms is shown.)   The ink set according to claim 5 or 6, wherein the acidic substance is a trivalent or less acidic substance.   The ink set according to any one of claims 5 to 7, wherein a concentration of the acidic substance is 40% by mass or less based on a total mass of the treatment liquid.   The ink set according to any one of claims 5 to 7, wherein the polyvalent metal salt is at least one polyvalent metal salt selected from a divalent metal salt and a trivalent metal salt.   The ink set according to claim 1, wherein the ink composition further includes resin particles.   A treatment liquid application step for applying a treatment liquid onto a recording medium using the ink set according to any one of claims 1 to 10 and an ink application step for applying an ink composition onto the recording medium. An image forming method.   The image forming method according to claim 11, wherein the recording medium is coated paper.   The image forming method according to claim 11 or 12, wherein an ink composition is applied on the recording medium by the ink application step after the treatment liquid is applied on the recording medium.   The image forming method according to claim 11, wherein the ink applying step forms an image by ejecting the ink composition by an ink jet method.