JP2015025076A - Ink composition for inkjet, ink set and image formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition for inkjet allowing formation of an image excellent in abrasion resistance, and suppression of thickening under a high-temperature environment.SOLUTION: An ink composition for inkjet contains water, a color material, a polymerizable compound, a polymerization initiator represented by the general formula (X), a polyfunctional (meth)acrylamide-type polymerizable compound, and wax particles having a melting point of 40°C or more and 140°C or less [R, R, R, R: a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an alkylthio group, a mercapto group, an acyl group, an amino group; n: an integer of 1 or more and 4 or less].

Description

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

  Ink-jet ink compositions (hereinafter also simply referred to as “inks”) used in image-forming methods by the inkjet method include solvent-based inks that use solvents as solvents, as well as considerations for the global environment and work environment. A water-based ink using water as a solvent has attracted attention.

Further, a technique for forming an image having high scratch resistance (hereinafter also referred to as “rubbing resistance”) by adding a polymerizable compound or a polymerization initiator to the ink and curing the ink has been studied.
For example, an ink composition containing a polyfunctional acrylamide type polymerizable compound having a specific structure and a polymerization initiator is known (see, for example, Patent Document 1).
Also known is an ink containing a coloring material, a polymerizable oligomer, a photopolymerization initiator, and water, wherein the photopolymerization initiator is a photopolymerization initiator having a solubility in water of 3% by weight or more (for example, Patent Document 2).
Further, an ultraviolet curable ink containing at least a coloring material, an ultraviolet polymerizable substance, and a photopolymerization initiator in an aqueous medium is known (see, for example, Patent Document 3).

On the other hand, a technique for improving the abrasion resistance of an image by incorporating wax particles in the ink has been studied.
For example, it contains a pigment coated with a water-insoluble resin, water-insoluble polymer particles having a glass transition temperature of 100 ° C. or higher, a solid wetting agent, a water-soluble organic solvent, wax particles having a melting point of 40 ° C. or higher and lower than 100 ° C., and water. Ink compositions are known (see, for example, Patent Document 4).
Also, a radiation curable paste comprising a curable wax that can be cured by free radical polymerization, a specific curable liquid component, a photoinitiator or photoinitiator portion, a curable gelling agent, and a colorant. Ink compositions are known (see, for example, Patent Document 5).

JP 2013-18846 A JP 2000-186242 A JP 2004-209976 A JP 2011-162692 A JP 2012-236998 A

  1- [4- (2-hydroxyethoxy) -phenyl], which is a polymerization initiator excellent in sensitivity to active energy rays such as ultraviolet rays and the like, as described in Patent Document 1 above. According to the ink containing 2-hydroxy-2-methyl-1-propan-1-one (hereinafter also referred to as “polymerization initiator Ia”), the image strength of the formed image can be improved. As a commercial item of this polymerization initiator Ia, Irgacure 2959 (trade name) (manufactured by BASF Japan Ltd.) can be mentioned.

  However, in order to further improve the abrasion resistance of the image, it is considered necessary to improve not only the image strength but also the slipperiness of the image. For this reason, it is considered that the rubbing resistance of the image is further improved by adding wax particles to the ink containing the polyfunctional acrylamide type polymerizable compound to impart slipperiness to the image.

  However, when the wax particles are added to the water-based ink containing the polyfunctional acrylamide-type polymerizable compound and the polymerization initiator Ia as a result of the study of the present inventors, the ink thickens over time in a high-temperature environment (hereinafter referred to as the following). It has been found that this phenomenon is also sometimes referred to as “high temperature aging stability decreases”.

This invention is made | formed in view of the above, and makes it a subject to achieve the following objectives.
That is, an object of the present invention is to provide an ink-jet ink composition which can form an image excellent in abrasion resistance and is excellent in high-temperature stability over time.
Another object of the present invention is to provide an ink set and an image forming method capable of forming an image excellent in abrasion resistance using an ink-jet ink composition excellent in high temperature aging stability.

Specific means for achieving the object are as follows.
<1> Inkjet containing water, a colorant, a polymerization initiator represented by the following general formula (X), a polyfunctional (meth) acrylamide type polymerizable compound, and wax particles having a melting point of 40 ° C. or higher and 140 ° C. or lower. Ink composition.

In general formula (X), R ^X1 , R ^X2 , R ^X3 , and R ^X4 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an alkylthio group, a mercapto group, an acyl group, or Represents an amino group. n represents an integer of 1 or more and 4 or less.

<2> The inkjet ink composition according to <1>, wherein the polyfunctional (meth) acrylamide type polymerizable compound is a (meth) acrylamide compound represented by the following general formula (1).

In general formula (1), R ¹ represents a hydrogen atom or a methyl group. R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. However, R ² does not have a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom of R ² . R ³ represents a divalent linking group. k represents 2 or 3. x, y, and z each independently represent an integer of 0 to 6, and x + y + z satisfies 0 to 18.

<3> The inkjet ink composition according to <1> or <2>, further including a water-soluble solvent represented by the following general formula (B).

  In General Formula (B), W represents a divalent linking group that forms a heterocyclic ring with the carbon atom and nitrogen atom in General Formula (B).

<4> The ink composition for inkjet according to any one of <1> to <3>, wherein the wax constituting the wax particles is carnauba wax.
<5> The inkjet ink composition according to <3>, wherein the water-soluble solvent represented by the general formula (B) is 2-pyrrolidone.
<6> Polymerization start wherein the mass content of 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one is represented by the general formula (X) The ink composition for inkjet according to any one of <1> to <5>, which is 5.0 times or less of the content of the agent.
<7> Any one of <1> to <6>, wherein the content of the wax particles is 0.2 to 10.0 times the content of the polymerization initiator represented by the general formula (X). Ink jet ink compositions described in 1. above.
<8> Any one of <1> to <7>, wherein the content of the wax particles is 0.3 to 8.0 times the content of the polymerization initiator represented by the general formula (X). Ink jet ink compositions described in 1. above.
<9> The content of the polymerization initiator represented by the general formula (X) is 0.1% by mass to 10.0% by mass with respect to the total amount of the inkjet ink composition. The ink composition for inkjet according to any one of the above.
<10><1> to <9, wherein the content of the polymerization initiator represented by the general formula (X) is 0.1% by mass to 5.0% by mass with respect to the total amount of the inkjet ink composition. The ink composition for inkjet according to any one of the above.

<11> The inkjet ink composition according to any one of <1> to <10>, and a treatment liquid containing an aggregating component that forms an aggregate when it comes into contact with the inkjet ink composition. An ink set.

<12> The ink set according to <11> is used, and a treatment liquid application step for applying the treatment liquid to a recording medium, and an image is formed by applying the inkjet ink composition to the recording medium by an inkjet method. And an ink application step.

According to the present invention, there is provided an ink-jet ink composition capable of forming an image excellent in abrasion resistance and excellent in high-temperature stability over time.
In addition, according to the present invention, there are provided an ink set and an image forming method capable of forming an image excellent in abrasion resistance using an ink jet ink composition excellent in high temperature aging stability.

It is a schematic block diagram which shows the structural example of the inkjet recording device used for implementation of image formation.

Hereinafter, the ink composition for inkjet according to the present invention, an ink set using the same, and an image forming method will be described in detail.
In this specification, the numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

≪Inkjet ink composition≫
The ink-jet ink composition of the present invention (hereinafter also simply referred to as “ink composition” or “ink”) is composed of water, a coloring material, a polymerization initiator represented by the following general formula (X) (hereinafter referred to as “specific polymerization”). Initiator ”), polyfunctional (meth) acrylamide type polymerizable compound (hereinafter also referred to as“ specific polymerizable compound ”), and wax particles having a melting point of 40 ° C. or higher and 140 ° C. or lower (hereinafter referred to as“ specific wax particles ”). ").
The ink composition of the present invention may contain other components as necessary.

As described above, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (polymerization initiator Ia) and polyfunctionality have been studied by the present inventors. When wax particles are added to an aqueous ink containing an acrylamide-type polymerizable compound in order to further improve the abrasion resistance of the image (particularly to improve the slipperiness of the image), It has been found that the viscosity of the ink may increase (i.e., stability at high temperatures decreases). When the viscosity of the ink is increased, the ejection stability of the ink from the inkjet head (nozzle) may be lowered.
Therefore, as a result of further investigation, the present inventor has found that the water-based ink described above uses a polymerization initiator represented by the following general formula (X) having high hydrophilicity, so that the formed image has abrasion resistance and ink. The present invention has been completed by finding that both high temperature aging stability can be achieved.
That is, according to the ink of the present invention, it is possible to form an image excellent in abrasion resistance and to improve the stability of the ink at high temperatures with time (that is, increase in the viscosity of the ink over time in a high temperature environment). Is suppressed).
Here, the effect of improving the abrasion resistance of the image obtained by the ink of the present invention is brought about by the image strength and the slipperiness of the image as described above.

  Furthermore, according to the ink of the present invention, the phenomenon (so-called “crying”) in which wax is separated and deposited on the surface of the formed image is also suppressed.

  Moreover, from the viewpoint of further improving the high temperature aging stability of the ink, the ink of the present invention preferably further contains a water-soluble solvent represented by the general formula (B) described later.

In the ink of the present invention, the content of the wax particles is preferably 0.01 to 100 times, more preferably 0.05 to 50 times the content of the polymerization initiator represented by the general formula (X). Preferably, 0.2 times to 10.0 times are more preferable, and 0.3 times to 8.0 times are particularly preferable.
When the content of the wax particles is 0.01 times or more of the content of the polymerization initiator represented by the general formula (X), the effect of improving the abrasion resistance of the image is more effectively exhibited.
When the content of the wax particles is 100 times or less than the content of the polymerization initiator represented by the general formula (X), the effect of improving the high temperature aging stability of the ink is more effectively exhibited.

  Hereinafter, each component of the ink composition of the present invention will be described.

<Wax particles>
The ink composition of the present invention contains at least one wax particle (specific wax particle) having a melting point of 40 ° C. or higher and 140 ° C. or lower.
As a result, the slipperiness of the formed image is improved, and as a result, the abrasion resistance of the image is improved.
Here, the wax particles having a melting point of 40 ° C. or more and 140 ° C. or less means that the melting point of the wax constituting the wax particles is 40 ° C. or more and 140 ° C. or less.

The melting point of the wax constituting the specific wax particles is 40 ° C. or higher and 140 ° C. or lower.
If the melting point is less than 40 ° C., the abrasion resistance of the image tends to deteriorate.
The melting point is preferably 45 ° C. or higher, more preferably 50 ° C. or higher, from the viewpoint of further improving the abrasion resistance of the image.

On the other hand, when the melting point exceeds 140 ° C., the abrasion resistance of the image tends to deteriorate. In addition, ink discharge properties tend to deteriorate.
The melting point is preferably 100 ° C. or less, and particularly preferably 95 ° C. or less, from the viewpoint of further improving the image abrasion resistance and ink ejection properties.

  Examples of the wax constituting the specific wax particles include natural wax and synthetic wax.

Examples of natural waxes include petroleum waxes, plant waxes, and animal and plant waxes.
Examples of petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum.
Examples of plant waxes include carnauba wax, candelilla wax, rice wax, and wood wax.
Examples of animal plant waxes include lanolin and beeswax.

Synthetic waxes include synthetic hydrocarbon waxes and modified waxes.
Examples of the synthetic hydrocarbon wax include polyethylene wax and Fischer-Tropsch wax.
Examples of the modified wax system include paraffin wax derivatives, montan wax derivatives, microcrystalline wax derivatives, and the like, and derivatives thereof.

  As the wax constituting the specific wax particles, carnauba wax is particularly preferable from the viewpoint of further improving the abrasion resistance of the image.

Commercially available products of specific wax particles include Cellosol 524, Trusol CN, Trusol PF60, Polylon L-787, Polylon P-502 (manufactured by Chukyo Yushi Co., Ltd.), ITOHWAX E-210 (manufactured by Ito Oil Co., Ltd.) Nopcoat PEM17 (manufactured by San Nopco Co., Ltd.), AQUACER 515 (manufactured by Big Chemie Japan Co., Ltd.) and the like.
Moreover, as specific wax particle | grains, ester A of the paragraph 0254 of Unexamined-Japanese-Patent No. 2011-162692 is mentioned.
Of these, carnauba wax is cellosol 524 and trasol CN.

Although there is no restriction | limiting in particular in content of the specific wax particle in the ink composition of this invention, From a viewpoint of improving the abrasion resistance of an image more, 0.01 mass%-20 mass with respect to the whole quantity of an ink composition. %, More preferably 0.1% by mass to 10% by mass, and particularly preferably 0.5% by mass to 5% by mass.
Moreover, the preferable range of the content mass of the specific wax particle with respect to the content mass of the polymerization initiator represented by general formula (X) is as above-mentioned.

  In addition, with regard to preferred forms of the specific wax particles (such as an organic solvent and a dispersion stabilizer that can be used when the specific wax particles are dispersed), the description in paragraphs 0154 to 0170 of JP2011-162692A can be appropriately referred to.

<Polymerization initiator>
The ink composition of the present invention contains at least one polymerization initiator represented by the following general formula (X) (specific polymerization initiator; hereinafter also referred to as “compound represented by general formula (X)”).

In general formula (X), R ^X1 , R ^X2 , R ^X3 , and R ^X4 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an alkylthio group, a mercapto group, an acyl group, or Represents an amino group. In general formula (X), n represents an integer of 1 or more and 4 or less.

The polymerization initiator represented by the general formula (X) is a polymerization initiator having higher hydrophilicity than the above-described polymerization initiator Ia.
When the ink composition of the present invention contains the polymerization initiator represented by the general formula (X), the increase in the viscosity of the ink over time in the high temperature environment described above is suppressed (that is, the high temperature aging of the ink). Stability is improved).

More specifically, when n is less than 1, the high temperature aging stability of the ink is lowered.
If n exceeds 4, the sensitivity will be insufficient, and this will reduce the abrasion resistance of the image.
N is more preferably 1 or more and 3 or less, and particularly preferably 1 or more and 2 or less.

  Further, when the ink of the present invention contains polymer particles, the polymerization initiator represented by the general formula (X) causes a phenomenon in which the polymer particles in the ink are aggregated and the discharge property is reduced due to the aggregation. The phenomenon is suppressed.

As described above, R ^{X1 to} R ^X4 are a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an alkylthio group, a mercapto group, an acyl group, or an amino group.

In R ^{X1 to} R ^X4 , the halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, more preferably a chlorine atom or a bromine atom, and particularly preferably a chlorine atom.

In R ^{X1 to} R ^X4 , the number of carbon atoms of the alkyl group is preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms.
In R ^{X1 to} R ^X4 , the alkyl group may be a linear alkyl group or a branched alkyl group. Moreover, the alkyl group may have an alicyclic structure.
^Examples of the alkyl group in R ^{X1 to} R ^X4 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, A cyclohexyl group is mentioned, A methyl group, an ethyl group, n-propyl group, and an isopropyl group are preferable.

In R ^{X1 to} R ^X4 , the number of carbon atoms of the alkoxy group is preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms.
In R ^{X1 to} R ^X4 , the alkoxy group may be a linear alkoxy group or a branched alkoxy group. Moreover, the alkoxy group may have an alicyclic structure.
As an alkoxy group in R ^{< X1} > -R < ^X4 >, a methoxy group, an ethoxy group, n-propyloxy group, isopropyloxy group, n-butoxy group, s-butoxy group, t-butoxy group, n-pentyloxy group, n- A hexyloxy group and a cyclohexyloxy group are mentioned, and a methoxy group, an ethoxy group, an n-propyloxy group, and an isopropyloxy group are preferable.

In R ^{X1 to} R ^X4 , the number of carbon atoms of the alkylthio group is preferably 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.
In R ^{X1 to} R ^X4 , the alkylthio group may be a linear alkylthio group or a branched alkylthio group. Moreover, the alkylthio group may have an alicyclic structure.
^Examples of the alkylthio group in R ^{X1 to} R ^X4 include methylthio group, ethylthio group, n-propylthio group, isopropylthio group, n-butylthio group, s-butylthio group, t-butylthio group, n-pentylthio group, and n-hexylthio group. And a cyclohexylthio group, and a methylthio group, an ethylthio group, an n-propylthio group, and an isopropylthio group are preferable.

In R ^{X1 to} R ^X4 , the number of carbon atoms of the acyl group is preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms.
In R ^{X1 to} R ^X4 , the acyl group may be a straight chain acyl group or a branched chain acyl group.
Examples of the acyl group in R ^{X1 to} R ^X4 include a formyl group, an acetyl group, an ethylacyl group, an n-propylacyl group, and an isopropylacyl group, and a formyl group, an acetyl group, and an ethylacyl group are preferable.

R ^{X1 to} R ^X4 are preferably a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or an alkylthio group, more preferably a hydrogen atom, an alkoxy group, or an alkylthio group, and most preferably a hydrogen atom.

Moreover, as a preferable form of the compound represented by general formula (X), the form whose 2 or more (preferably 3 or more, most preferably 4) is a hydrogen atom among R ^{< X1} > -R < ^X4 > is mentioned. .

  Hereinafter, although the specific example (exemplary compound) of a compound represented by general formula (X) is shown, the compound represented by general formula (X) is not limited to these.

  The compound represented by the general formula (X) (specific polymerization initiator) can be synthesized, for example, according to the method described in paragraphs 0067 to 0071 and 0112 to 0115 of JP-A No. 2000-186242.

Although there is no restriction | limiting in particular in content of the compound (specific polymerization initiator) represented by general formula (X) in the ink composition of this invention, 0.05 mass%-10. 0 mass% is preferable, 0.08 mass% to 10.0 mass% is more preferable, 0.1 mass% to 10.0 mass% is still more preferable, 0.1 mass% to 8.0 mass% is still more preferable. 0.1 mass% to 5.0 mass% is particularly preferable.
When the content is 0.05% by mass or more, sensitivity is further improved, and image abrasion resistance is further improved.
When the content is 10.0% by mass or less, the high temperature aging stability of the ink composition is further improved. Furthermore, when the content is 10.0% by mass or less, the total amount of non-volatile components can be reduced, thereby further improving the abrasion resistance of the image.

In addition to the above specific polymerization initiator, the ink composition of the present invention further comprises 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (polymerization). Initiator Ia) may be included.
This polymerization initiator Ia is a polymerization initiator excellent in sensitivity as described above, and a commercially available product can be obtained at low cost. Therefore, when the specific polymerization initiator and the polymerization initiator Ia are used in combination, the production cost of the ink composition can be reduced.

In the ink composition of the present invention, the content of the polymerization initiator Ia is preferably 5.0 times or less, more preferably 1.0 or less, more preferably 0.5 times the content of the specific polymerization initiator. It is particularly preferable that the ratio is not more than twice.
If the content mass of the polymerization initiator Ia is 5.0 times or less of the mass content of the specific polymerization initiator, the effect of improving the high temperature aging stability by the specific polymerization initiator is more suitably maintained.
Here, “the content of the polymerization initiator Ia is not more than 5.0 times the content of the specific polymerization initiator” means that the ink composition of the present invention does not contain or contains the polymerization initiator Ia. When it does, it means that the content mass of the polymerization initiator Ia is not more than 5.0 times the mass content of the specific polymerization initiator. The same applies to the meanings of “1.0 times or less” and “0.5 times or less”.

The ink composition of the present invention further comprises 2-hydroxy-2-methyl-1-phenyl-propan-1-one (hereinafter also referred to as “polymerization initiator Ib”) in addition to the specific polymerization initiator. May be included.
As a commercial item of polymerization initiator Ib, Darocur 1173 (made by BASF Japan) etc. can be mentioned, for example.
In this case, the preferable range of the content of the polymerization initiator Ib relative to the content of the specific polymerization initiator is the same as the above-described preferable range of the content of the polymerization initiator Ia relative to the content of the specific polymerization initiator.

The ink composition of the present invention may contain the specific polymerization initiator, the polymerization initiator Ia, and the polymerization initiator Ib.
In this case, the preferable range of the total content mass of the polymerization initiator Ia and the polymerization initiator Ib with respect to the content mass of the specific polymerization initiator is the above-described content mass of the polymerization initiator Ia with respect to the mass content of the specific polymerization initiator. This is the same as the preferred range.

The ink composition of the present invention may contain a polymerization initiator other than the above.
Other polymerization initiators may be selected as appropriate from compounds that can initiate a polymerization reaction with active energy rays. For example, active species (radicals, acids, bases, etc.) by radiation or light, or electron beams. ) Can be used. For example, a photoinitiator or the like can be used.
Examples of other polymerization initiators include hydroxyalkylphenone initiators, acetophenone initiators, benzophenone initiators, benzoin initiators, benzoin ether initiators, aminoalkylphenone initiators, xanthone initiators, Examples include oxime initiators.
For example, examples of the hydroxyalkylphenone-based initiator include 1-hydroxycyclohexyl phenyl ketone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, and the like.
Examples of acetophenone-based initiators include acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophene, and the like.
Examples of the benzophenone initiator include benzophenone, 2-chlorobenzophenone, p, p′-dichlorobenzophene, p, p′-bisdiethylaminobenzophenone, Michler's ketone, and the like.
Examples of the benzoin initiator and benzoin ether initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-propyl ether, benzoin isobutyl ether, benzoin n-butyl ether and the like.

The content of the total polymerization initiator in the ink composition of the present invention (the total content when there are two or more polymerization initiators) is preferably 0.1% by mass to 15.0% by mass, 1 mass%-10.0 mass% are more preferable, 0.15 mass%-8.0 mass% are still more preferable, 0.2 mass%-5.0 mass% are especially preferable.
When the content of the total polymerization initiator is 0.1% by mass or more, the sensitivity is further improved and the image strength is further improved.
When the content is 15.0% by mass or less, the high temperature aging stability of the ink can be further improved. Furthermore, the total amount of non-volatile components can be reduced, thereby improving the image intensity.

<Polymerizable compound>
The ink composition of the present invention contains at least one polyfunctional (meth) acrylamide type polymerizable compound (specific polymerizable compound).
When applied to a recording medium, the ink composition of the present invention is cured by polymerization of a specific polymerizable compound contained in the ink composition. Thereby, the image formed using the ink composition of the present invention is reinforced.
Here, “(meth) acrylamide” means at least one of methacrylamide and acrylamide.
The “(meth) acrylamide type polymerizable compound” is a compound having a (meth) acrylamide structure in the molecule and polymerized by irradiation with active energy rays.
The “polyfunctional (meth) acrylamide type polymerizable compound” is a compound having two or more (meth) acrylamide structures in the molecule and polymerized by irradiation with active energy rays.

The polyfunctional (meth) acrylamide type polymerizable compound is preferably a water-soluble polymerizable compound.
In the present invention, that the polymerizable compound is “water-soluble” means that the polymerizable compound can be dissolved in water at a certain concentration or more. Specifically, the solubility of the polymerizable compound in water at 25 ° C. is preferably 5% by mass or more, and more preferably 10% by mass or more. The water-soluble polymerizable compound is preferably one that can be dissolved (desirably uniformly) in the aqueous ink composition. Further, the solubility may be increased by adding a water-soluble solvent to be described later, and it may be dissolved (desirably uniformly) in the ink composition.

  As the polyfunctional (meth) acrylamide type polymerizable compound, a compound represented by the following general formula (M) is preferable.

In general formula (M), Q represents an n-valent group, and R ¹ represents a hydrogen atom or a methyl group. N represents an integer of 2 or more.

The compound represented by the general formula (M) is a compound in which an unsaturated vinyl monomer is bonded to the group Q through an amide bond.
R ¹ represents a hydrogen atom or a methyl group, preferably a hydrogen atom.
The valence n of the group Q is 2 or more from the viewpoint of improving permeability, polymerization efficiency, and ejection stability, and is preferably 2 or more and 6 or less, more preferably 2 or more and 4 or less.
Examples of the group Q include substituted or unsubstituted alkylene groups having 4 or less carbon atoms such as methylene, ethylene, propylene, and butylene groups, saturated or unsaturated hetero rings (pyridine ring, imidazole ring, pyrazine ring, piperidine ring, piperazine). A divalent or higher valent linking group having a ring, a morpholine ring, etc., and a divalent or higher valent alkylene group (preferably oxyethylene group) of a polyol compound containing an oxyalkylene group (preferably oxyethylene group). Examples of the divalent or higher residue of the polyol compound containing 3 or more can be given.

  With respect to the compound represented by the general formula (M), descriptions in paragraphs 0019 to 0034 of JP 2013-43946 A, paragraphs 0070 to 0080 of JP 2013-43945 A, and the like can be appropriately referred to.

Among polyfunctional (meth) acrylamide-type polymerizable compounds, a (meth) acrylamide compound represented by the following general formula (1) (hereinafter simply referred to as “general formula (1)” in that it has high polymerization ability and curing ability. Also referred to as "compound represented") is particularly preferred.
This compound has four acrylamide groups or methacrylamide groups as polymerizable groups in the molecule. In addition, this compound exhibits curability based on a polymerization reaction due to application of energy such as active energy rays such as α rays, γ rays, X rays, ultraviolet rays, visible rays, infrared rays, and electron beams, and heat. The compound represented by the general formula (1) exhibits water solubility and dissolves well in water-soluble solvents such as water and alcohol.
Further, the compound represented by the general formula (1) is also preferable from the viewpoint of ink dischargeability (particularly, continuous dischargeability).

((Meth) acrylamide compound represented by general formula (1))
In the ink composition of the present invention, as described above, at least one of the polymerizable compounds is preferably a (meth) acrylamide compound represented by the following general formula (1).

In general formula (1), R ¹ represents a hydrogen atom or a methyl group. R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. However, R ² does not have a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom of R ² . R ³ represents a divalent linking group. k represents 2 or 3. x, y, and z each independently represent an integer of 0 to 6, and x + y + z satisfies 0 to 18.

In general formula (1), R ¹ represents a hydrogen atom or a methyl group. Several R < ¹ > may mutually be same or different. R ¹ is preferably a hydrogen atom.

In the general formula (1), R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. A plurality of R ² may be the same as or different from each other. R ² is preferably an alkylene group having 3 to 4 carbon atoms, more preferably an alkylene group having 3 carbon atoms, and particularly preferably a linear alkylene group having 3 carbon atoms. The alkylene group for R ² may further have a substituent, and examples of the substituent include an aryl group and an alkoxy group.
However, R ² does not have a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom of R ² . R ² is a linear or branched alkylene group linking an oxygen atom and a nitrogen atom of the (meth) acrylamide group. When the alkylene group has a branched structure, the oxygen atom at both ends and the nitrogen of the (meth) acrylamide group It is also conceivable to take an —O—C—N— structure (hemaminal structure) in which an atom is bonded to the same carbon atom in an alkylene group. However, the compound represented by the general formula (1) does not include a compound having such a structure. Thereby, the decomposition at the position of the carbon atom of the —O—C—N— structure is suppressed, and the storage stability of the ink composition can be further improved.

In general formula (1), R ³ represents a divalent linking group. Examples of the divalent linking group for R ³ include an alkylene group, an arylene group, a heterocyclic group, or a group composed of a combination thereof, and an alkylene group is preferable. When the divalent linking group includes an alkylene group, the alkylene group may further include at least one group selected from —O—, —S—, and —NR ^a —. R ^a represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

When R ³ contains an alkylene group, examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, and a nonylene group. The number of carbon atoms of the alkylene group of R ³ is preferably 1 to 6, more preferably 1 to 3, and particularly preferably 1.
The alkylene group for R ³ may further contain at least one selected from —O—, —S—, and —NR ^a —. Examples of the alkylene group containing —O— include —C— ₂ H ₄ —O—C ₂ H ₄ —, —C ₃ H ₆ —O—C ₃ H ₆ — and the like can be mentioned.
The alkylene group for R ³ may further have a substituent, and examples of the substituent include an aryl group and an alkoxy group.

When R ³ includes an arylene group, examples of the arylene group include a phenylene group and a naphthylene group. The number of carbon atoms of the arylene group of R ³ is preferably 6 to 14, and is 6 to 10 More preferably, 6 is particularly preferable.
The arylene group for R ³ may further have a substituent, and examples of the substituent include an alkyl group and an alkoxy group.

When R ³ contains a heterocyclic group, the heterocyclic group is preferably a 5-membered or 6-membered ring, which may be further condensed. Further, it may be an aromatic heterocyclic ring or a non-aromatic heterocyclic ring. Specific examples of the heterocyclic group when R ³ includes a heterocyclic group include pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, cinnoline, phthalazine, quinoxaline, pyrrole, indole, furan, benzofuran, and thiophene. , Benzothiophene, pyrazole, imidazole, benzimidazole, triazole, oxazole, benzoxazole, thiazole, benzothiazole, isothiazole, benzisothiazole, thiadiazole, isoxazole, benzisoxazole, pyrrolidine, piperidine, piperazine, imidazolidine, thiazoline, etc. Is mentioned. Of these, an aromatic heterocyclic group is preferable, and pyridine, pyrazine, pyrimidine, pyridazine, triazine, pyrazole, imidazole, benzimidazole, triazole, thiazole, benzothiazole, isothiazole, benzisothiazole, and thiadiazole are preferable. In addition, although the heterocyclic group shown above is illustrated in a form in which the substitution position is omitted, the substitution position is not limited. For example, in the case of pyridine, substitution is made at the 2-position, 3-position, and 4-position. It is possible to include all of these substitutions. The heterocyclic group may further have a substituent, and examples of the substituent include an alkyl group, an aryl group, and an alkoxy group.

In general formula (1), k represents 2 or 3. Several k may mutually be same or different. C _k H _2k may have a linear structure or a branched structure.

  In general formula (1), x, y, and z each independently represent an integer of 0 to 6, preferably an integer of 0 to 5, and more preferably an integer of 0 to 3. x + y + z satisfies 0-18, is preferably 0-15, and is more preferably 0-9.

  Specific examples (polymerizable compounds a to f) of the compound represented by the general formula (1) are shown below, but the compound represented by the general formula (1) is not limited thereto.

  Although there is no restriction | limiting in particular in the synthesis | combining method of the compound represented by General formula (1), For example, it can synthesize | combine by the method described in Unexamined-Japanese-Patent No. 2013-18846 Paragraph 0028-0033 and Paragraph 0123-0139.

When the ink composition of the present invention contains the compound represented by the general formula (1) described above, the ink composition may contain only one type of the compound represented by the general formula (1), You may contain 2 or more types.
When the ink composition of the present invention contains the compound represented by the above general formula (1), the content of the compound represented by the general formula (1) is 0. 0 relative to the total amount of the ink composition. 1 mass%-45 mass% are preferable, 0.5 mass%-30 mass% are more preferable, 0.8 mass%-20 mass% are especially preferable. When the content of the compound represented by the general formula (1) is within the above range, the curability and storage stability of the ink composition are further improved.

In the ink composition of the present invention, the proportion of the (meth) acrylamide compound represented by the general formula (1) in the total polymerizable compound contained in the ink composition is 50% by mass or more (more preferably). Is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more.
This form is remarkably excellent in curability and continuous ink ejection.

(Other polymerizable compounds)
The ink composition of the present invention may contain other polymerizable compounds in addition to the specific polymerizable compound.
Examples of other polymerizable compounds include monofunctional (meth) acrylamide compounds.
Monofunctional (meth) acrylamide compounds include diacetone acrylamide, hydroxyethyl acrylamide, hydroxypropyl acrylamide, N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propenamide, N- (2-dimethylamino) Ethyl) acrylamide, dimethylaminopropylacrylamide, 2- (acryloyloxy) -N, N, N-trimethylethanaminium chloride, (3-acrylamidopropyl) trimethylammonium chloride, 2-acrylamido-2-methylpropanesulfonic acid, N -[1,1-dimethyl-2- (sodiooxysulfonyl) ethyl] acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, 4-acryloylmorpholine and the like. That.
As the monofunctional (meth) acrylamide compound, the descriptions in 0041 to 0050 of JP2013-18846A can be referred to as appropriate.

  Other polymerizable compounds include, for example, nonionic polymerizable monomers and cationic polymerizable monomers described in paragraphs 0149 to 0169 of Japanese Patent Application Laid-Open No. 2011-46872.

<Water>
The ink composition of the present invention contains water.
The content of water in the ink composition is not particularly limited, but the content can be 50% by mass or more.
Usually, when the water content is 50% by mass or more, the above-mentioned high-temperature stability tends to decrease.
However, the ink composition of the present invention can suppress a decrease in stability over time even when the water content is 50% by mass or more due to the action of the specific polymerization initiator.
The preferable content of water in the ink composition is preferably 50% by mass to 80% by mass, more preferably 50% by mass to 75% by mass, and still more preferably 50% by mass with respect to the total amount of the ink composition. -70 mass%.

<Water-soluble solvent>
The ink composition of the present invention preferably contains at least one water-soluble solvent represented by the following general formula (B).
Thereby, the high temperature aging stability of the ink composition can be further improved.

  In the general formula (B), W represents a linking group that forms a heterocyclic ring together with the carbon atom and the nitrogen atom in the general formula (B).

In general formula (B), W is preferably an alkylene group.
This alkylene group may be unsubstituted or substituted with a substituent. Examples of the substituent include an alkyl group (preferably a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms), a hydroxy group, a hydroxyalkyl group (preferably a hydroxyalkyl group having 1 to 6 carbon atoms). ) Is preferred.
The preferable range of the number of carbon atoms of the alkylene group (including the number of carbon atoms of the substituent when it has a substituent) is 1 to 10.
Moreover, the number of heterocycles in the general formula (B) is preferably 3-6.

  Specific examples of the compound represented by the general formula (B) include 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2- Examples include pyrrolidone, 1-pentyl-2-pyrrolidone, 1-hexyl-2-pyrrolidone, 1-hydroxyethyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone and the like. Among these, 2-pyrrolidone is preferable from the viewpoint of further improving the abrasion resistance of the image.

When the ink composition of the present invention contains the water-soluble solvent represented by the general formula (B), the content of the compound represented by the general formula (B) (in the case of two or more kinds, the total content) ) Is preferably 0.1% by mass to 20% by mass with respect to the total amount of the ink composition.
When the content is 0.1% by mass or more, the high temperature aging stability of the ink composition can be remarkably improved.
Moreover, since the polymerizable compound can be sufficiently contained in the ink composition when the content is 20% by mass or less, the curability of the ink composition can be improved.
The content is more preferably 0.2% by mass to 15% by mass, further preferably 0.3% by mass to 12% by mass, and 0.4% by mass with respect to the total amount of the ink composition. It is particularly preferably 10 to 10% by mass.

(Other water-soluble solvents)
When the ink composition of the present invention contains a water-soluble solvent, the water-soluble solvent is represented by the general formula (B) instead of the water-soluble solvent represented by the general formula (B). In addition to the water-soluble solvent, other water-soluble solvents can also be used.
However, from the viewpoint of high temperature aging stability of the ink, when the ink composition of the present invention contains a water-soluble solvent, the water-soluble solvent contained is a water-soluble solvent represented by the above general formula (B). It is preferable to include.

Examples of other water-soluble solvents include glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, and dipropylene glycol. Glycols, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-hexanediol, In addition to polyhydric alcohols such as alkanediols such as 1,2-pentanediol and 4-methyl-1,2-pentanediol, saccharides and sugar alcohols described in paragraph 0116 of JP2011-42150A, Hyaluronic acid having 1 to 4 carbon atoms Le kill alcohols, glycol ethers, and the like. These solvents can be used singly or in combination of two or more. Polyhydric alcohols are also useful as drying inhibitors and wetting agents, and examples include the examples described in paragraph 0117 of JP-A-2011-42150. Moreover, a polyol compound is preferable as a penetrant, and examples of the aliphatic diol include those described in paragraph 0117 of JP2011-42150A.
As other water-soluble solvents, for example, water-soluble solvents described in paragraphs 0176 to 0179 of JP2011-46872A, and paragraphs 0063 to 0074 of JP2013-18846A are described. It is also possible to appropriately select from the water-soluble solvents that are present.

  Moreover, as another water-soluble solvent, the water-soluble solvent represented by the following general formula (A) can also be used.

In general formula (A), R ^A1 represents a linear or branched alkyl group having 1 to 6 carbon atoms. R ^A2 and R ^A3 each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.

The water-soluble solvent represented by the general formula (A) is a β-alkoxypropionamide compound as shown in the above structure.
The water-soluble solvent represented by the general formula (A) can increase the compatibility between the polymerization initiator and water while maintaining the solubility of the polymerization initiator in the ink composition. Moreover, since this compound has a small environmental load and little odor, the ink composition is easy to handle.

In the general formula (A), the linear or branched alkyl group having 1 to 6 carbon atoms represented by R ^A1 is methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl. Group, n-pentyl group, n-hexyl group and the like.
In the general formula (A), examples of the linear or branched alkyl group having 1 to 6 carbon atoms represented by R ^A2 and R ^A3 include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, Examples thereof include a tert-butyl group.

Among them, the alkyl group represented by R ^A1 preferably has 3 to 6 carbon atoms, and is a propyl group, isopropyl group, n-butyl group, tert-butyl group, n-pentyl group, and n-hexyl group. Is more preferable.
The alkyl group represented by R ^A2 or R ^A3 preferably has 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group.

  Hereinafter, as the water-soluble solvent represented by the general formula (A), 3-methoxy-N, N-dimethylpropionamide, 3-n-butoxy-N, N-dimethylpropionamide, 3-ethoxy-N, N-diethylpropionamide, 3-methoxy-N, N-diethylpropionamide, 3-methoxy-N, N-monomethylmonoethylpropionamide, 3-methoxy-N, N-di-n-propylpropionamide, 3- Methoxy-N, N-di-n-butylpropionamide, 3-methoxy-N, N-di-n-butylpropionamide, 3-ethoxy-N, N-dimethylpropionamide, 3-ethoxy-N, N- Monomethylmonoethylpropionamide, 3-ethoxy-N, N-di-n-propylpropionamide, 3-ethoxy-N, N-di-n-butyl Lupropionamide, 3-n-butoxy-N, N-diethylpropionamide, 3-n-butoxy-N, N-monomethylmonoethylpropionamide, 3-n-butoxy-N, N-di-n-propylpropion Amide, 3-n-butoxy-N, N-di-n-butylpropionamide, 3-n-propoxy-N, N-dimethylpropionamide, 3-n-propoxy-N, N-diethylpropionamide, 3- n-propoxy-N, N-monomethylmonoethylpropionamide, 3-n-propoxy-N, N-di-n-propylpropionamide, 3-n-propoxy-N, N-di-n-butylpropionamide, 3-iso-propoxy-N, N-dimethylpropionamide, 3-iso-propoxy-N, N-diethylpropionamide 3-1 so-propoxy-N, N-monomethylmonoethylpropionamide, 3-iso-propoxy-N, N-di-n-propylpropionamide, 3-iso-propoxy-N, N-di-n-butylpropion Amide, 3-tert-butoxy-N, N-dimethylpropionamide, 3-tert-butoxy-N, N-diethylpropionamide, 3-tert-butoxy-N, N-monomethylmonoethylpropionamide, 3-tert- Butoxy-N, N-di-n-propylpropionamide, 3-tert-butoxy-N, N-di-n-butylpropionamide, 3-hexyloxy-N, N-dimethylpropionamide, 3-hexyloxy- N, N-diethylpropionamide. Of these, 3-n-butoxy-N, N-dimethylpropionamide is most preferable.

The compound represented by general formula (A) may be used individually by 1 type, and may use 2 or more types together.
A specific method for producing the compound represented by the general formula (A) can be produced, for example, based on a synthesis method described in JP2009-185079A or International Publication No. 2008/102615. Moreover, the compound represented by general formula (A) may use a commercial item, for example, can be obtained as "Examide" by Idemitsu Kosan Co., Ltd.
In addition, the compound represented by the general formula (B) is more preferable than the compound represented by the general formula (A) in that the thickening at high temperature with time can be suppressed.

When the ink composition of the present invention contains a water-soluble solvent, the content of the water-soluble solvent (the total content when there are two or more) is 2% by mass to 30% by mass with respect to the total amount of the ink composition. % Is preferred.
When the total content is 2% by mass or more, the solubility of the polymerization initiator in the ink composition can be further increased.
Moreover, since the polymerizable compound can be sufficiently contained in the ink composition when the total content is 30% by mass or less, the curability of the ink composition can be improved.
The total content is more preferably 3% by mass to 25% by mass and further preferably 4% by mass to 20% by mass with respect to the total amount of the ink composition.

<Polymer particles>
The ink composition of the present invention preferably contains at least one polymer particle.
Thereby, the abrasion resistance of the image is further improved.
The polymer particles are particles made of a polymer that is present separately from the pigment, unlike a polymer dispersant (a polymer dispersant that covers at least a part of the pigment) described later.
For example, when an image is formed by applying the ink composition to a recording medium together with a treatment liquid described later, the polymer particles are contained in the ink composition when contacting the treatment liquid or a region where the treatment liquid is dried. The ink composition has a function of fixing the ink composition by destabilizing and agglomerating and thickening. Thereby, the abrasion resistance of the image is further improved, and image unevenness is further suppressed. Furthermore, the adhesion of the ink composition to the recording medium and the scratch resistance of the image are further improved.

The glass transition temperature (Tg) of the polymer particles is preferably 90 ° C. or higher and more preferably 100 ° C. or higher from the viewpoint of further improving the abrasion resistance of the image.
The glass transition temperature of the polymer particles is preferably 250 ° C. or lower, and more preferably 230 ° C. or lower. When the glass transition temperature of the polymer particles is 250 ° C. or lower, the polymer particles are fused in the drying process, and the image strength and abrasion resistance are further improved.

Here, the measured Tg obtained by actual measurement is applied to the glass transition temperature (Tg) of the polymer particles.
Specifically, the measurement Tg means a value measured under normal measurement conditions using a differential scanning calorimeter (DSC) EXSTAR 6220 manufactured by SII Nanotechnology. However, when measurement is difficult due to polymer decomposition or the like, calculation Tg calculated by the following calculation formula is applied. The calculation Tg is calculated by the following equation (1).
1 / Tg = Σ (X _i / Tg _i ) (1)
Here, it is assumed that n types of monomer components from i = 1 to n are copolymerized in the polymer to be calculated. X _i is the weight fraction of the i-th monomer (ΣX _i = 1), and Tg _i is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. However, Σ is the sum from i = 1 to n. As the glass transition temperature value (Tg _i ) of the homopolymer of each monomer, the value of Polymer Handbook (3rd Edition) (by J. Brandrup, EH Immergut (Wiley-Interscience, 1989)) is adopted. .

The polymer particles are preferably polymer particles obtained by a phase inversion emulsification method, and the following self-dispersing polymer particles (self-dispersing polymer particles) are more preferable.
Here, the self-dispersing polymer is dispersed in an aqueous medium by a functional group (particularly an acidic group or a salt thereof) possessed by the polymer itself when it is dispersed by a phase inversion emulsification method in the absence of a surfactant. A water-insoluble polymer that can be in a state.
Here, the dispersed state refers to an emulsified state (emulsion) in which a water-insoluble polymer is dispersed in an aqueous medium and a dispersed state (suspension) in which a water-insoluble polymer is dispersed in an aqueous medium. It includes both states.
“Water-insoluble” means that the amount dissolved in 100 parts by mass of water (25 ° C.) is 5.0 parts by mass or less.

  As the phase inversion emulsification method, for example, a polymer is dissolved or dispersed in a solvent (for example, a water-soluble solvent) and then poured into water as it is without adding a surfactant. A method of obtaining an aqueous dispersion in an emulsified or dispersed state after stirring and mixing with the neutralized (for example, acidic group) and removing the solvent.

  As the self-dispersing polymer particles, the self-dispersing polymer particles described in paragraphs 0090 to 0121 of JP2010-64480A and paragraphs 0130 to 0167 of JP2011-066805A can be used.

From the viewpoints of easily adjusting the glass transition temperature to 90 ° C. or more and maintaining good dispersion stability, preferred forms of the copolymerization ratio of the polymer constituting the polymer particles are as follows.
That is, from the above viewpoint, the preferred form is that the polymer constituting the polymer particles has a structural unit having an aromatic group (preferably benzyl group or phenoxy group) as a copolymerization ratio of 3% by mass to 45% by mass (more preferably 3 to 40% by mass, particularly preferably 5 to 30% by mass) and a hydrophilic structural unit (preferably a structural unit derived from (meth) acrylic acid) as a copolymerization ratio of 2 to 30% by mass (more Preferably 5% by mass to 20% by mass, particularly preferably 5% by mass to 15% by mass) and a structural unit having an alkyl group as a copolymerization ratio of 5% by mass to 90% by mass (more preferably 30% by mass to 90% by mass). Mass%, more preferably 50 mass% to 90 mass%, particularly preferably 60 mass% to 85 mass%).
A more preferable form of the polymer particle is 3% by mass to 45% by mass (more preferably) with at least one of a structural unit derived from benzyl (meth) acrylate or a structural unit derived from phenoxyethyl (meth) acrylate as a copolymerization ratio. 3 to 40% by mass, particularly preferably 5 to 30% by mass) and a structural unit derived from (meth) acrylic acid as a copolymerization ratio of 2 to 30% by mass (more preferably 5 to 20% by mass, Particularly preferably 5 mass% to 15 mass%) and a structural unit derived from alkyl (meth) acrylate as a copolymerization ratio of 40 mass% to 90 mass% (more preferably 50 mass% to 90 mass%, particularly preferably 60 mass% to 85 mass%).

  The molecular weight range of the polymer constituting the polymer particles is preferably 3000 to 200,000 in terms of weight average molecular weight, more preferably 5000 to 150,000, and still more preferably 10,000 to 100,000. 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.

  In addition, the weight average molecular weight of the polymer which comprises a polymer particle is measured by a gel permeation chromatograph (GPC). GPC uses HLC-8020GPC (manufactured by Tosoh Corporation), TSKgel, Super Multipore HZ-H (manufactured by Tosoh Corporation, 4.6 mm ID × 15 cm) as columns, and THF (tetrahydrofuran) as an eluent. ) Is used. The conditions are as follows: the sample concentration is 0.45 mass%, the flow rate is 0.35 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and the RI 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 average particle size of the polymer particles (preferably self-dispersing polymer particles) is preferably in the range of 10 to 400 nm, more preferably in the range of 10 to 200 nm, still more preferably in the range of 10 to 100 nm in terms of volume average particle size. Is in the range of 10-50 nm. Manufacturability is improved when the volume average particle diameter is 10 nm or more. Moreover, storage stability improves that a volume average particle diameter is 400 nm or less. The particle size distribution of the polymer particles is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Further, two or more kinds of polymer particles may be mixed and used.
The average particle size and particle size distribution of the polymer particles are determined by measuring the volume average particle size by a dynamic light scattering method using a nanotrack particle size distribution measuring device UPA-EX150 (manufactured by Nikkiso Co., Ltd.). It is what

When the ink composition of the present invention contains the above-described polymer particles, the content (the total content in the case of two or more types) is not particularly limited, but is 0 with respect to the total amount of the ink composition. .3% by mass to 10.0% by mass is preferable, 0.5% by mass to 7.0% by mass is more preferable, and 1.0% by mass to 5.0% by mass is particularly preferable.
When the content is 0.3% by mass or more, the abrasion resistance of the image can be further improved, and image unevenness can be further suppressed.
When the content is 10.0% by mass or less, the ink ejection property can be further improved, and it is also advantageous in terms of the high temperature aging stability of the ink.

  When the ink composition of the present invention contains the above-described polymer particles, the content ratio of the polymer particles to the wax particles is in the range of polymer particles: wax particles = 1: 5 to 5: 1 (solid content Ratio). When the content mass ratio is within this range, the image has excellent abrasion resistance.

<Color material>
The ink composition of the present invention contains at least one coloring material.
The color material is not particularly limited, and may be a pigment or a dye.

(Pigment)
There is no restriction | limiting in particular as a pigment, According to the objective, it can select suitably, For example, any of an organic pigment and an inorganic pigment may be sufficient. The pigment is preferably a pigment that is almost insoluble or hardly soluble in water from the viewpoint of ink colorability.

  Examples of organic pigments 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 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.

  When an organic pigment is used, the average particle diameter of the organic pigment is preferably small from the viewpoint of transparency and color reproducibility, but is preferably large from the viewpoint of light resistance. From the viewpoint of achieving both, the average particle size is preferably 10 to 200 nm, more preferably 10 to 150 nm, and even more preferably 10 to 120 nm. The particle size distribution of the organic pigment is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Two or more kinds of organic pigments having a monodispersed particle size distribution may be mixed and used.

-Dispersant-
The ink composition of the present invention can contain at least one dispersant.
That is, when a pigment is used in the ink composition of the present invention, the pigment is preferably dispersed by a dispersant.
The pigment dispersant may be either a polymer dispersant or a low molecular surfactant type dispersant. The polymer dispersant may be either a water-soluble dispersant or a water-insoluble dispersant.

  As the low molecular surfactant type dispersant, for example, known low molecular surfactant type dispersants described in paragraphs 0047 to 0052 of JP2011-178029A can be used.

  Among polymer dispersants, water-soluble dispersants include hydrophilic polymer compounds. For example, natural hydrophilic polymer compounds include plant polymers such as gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, seaweeds such as alginic acid, carrageenan and agar. Examples include molecules, animal polymers such as gelatin, casein, albumin and collagen, and microorganism polymers such as xanthene gum and dextran.

In addition, in hydrophilic polymer compounds modified from natural products, fiber polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, starch such as sodium starch glycolate and sodium starch phosphate And seaweed polymers such as sodium alginate, propylene glycol alginate, and the like.
Further, synthetic hydrophilic polymer compounds include vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, non-crosslinked polyacrylamide, polyacrylic acid or alkali metal salts thereof, water-soluble styrene acrylic resins, and the like. Acrylic resin, water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic acid resin, polyvinyl pyrrolidone, polyvinyl alcohol, β-naphthalene sulfonic acid formalin condensate alkali metal salt, quaternary ammonium and amino And a polymer compound having a salt of a cationic functional group such as a group in the side chain, a natural polymer compound such as shellac, and the like.

  Among these, water-soluble dispersants introduced with carboxyl groups are hydrophilic polymers such as homopolymers of acrylic acid, methacrylic acid, styrene acrylic acid, and copolymers with monomers having other hydrophilic groups. Preferred as a compound.

  Among the polymer dispersants, as the water-insoluble dispersant, a polymer having both a hydrophobic portion and a hydrophilic portion can be used. For example, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer, (meth) acrylic acid ester- (meth) acrylic acid copolymer, polyethylene glycol ( Examples thereof include (meth) acrylate- (meth) acrylic acid copolymers, vinyl acetate-maleic acid copolymers, and styrene-maleic acid copolymers.

The weight average molecular weight of the polymer dispersant is preferably 3,000 to 100,000, more preferably 5,000 to 50,000, still more preferably 5,000 to 40,000, and particularly preferably 10,000. 000 to 40,000.
In addition, the weight average molecular weight of a polymer dispersing agent is measured similarly to the weight average molecular weight of the polymer which comprises the above-mentioned polymer particle.

  The polymer dispersant preferably contains a polymer having a carboxyl group from the viewpoints of self-dispersibility and aggregation rate when the treatment liquid comes into contact. The polymer dispersant has a carboxyl group and has an acid value of 100 mgKOH / g or less. It is preferable that the polymer has an acid value of 25 to 100 mgKOH / g. In particular, when the ink composition of the present invention is used together with a treatment liquid for aggregating components in the ink composition, a polymer dispersant having a carboxyl group and an acid value of 25 to 100 mgKOH / g is effective. . The processing liquid will be described later.

  The mixing mass ratio (p: s) between the pigment (p) and the dispersant (s) is preferably in the range of 1: 0.06 to 1: 3, more preferably in the range of 1: 0.125 to 1: 2. Preferably, it is 1: 0.125 to 1: 1.5.

The ink composition of the present invention preferably contains a pigment and a dispersant from the viewpoint of image light resistance and quality, and contains an organic pigment and a polymer dispersant (preferably a polymer dispersant containing a carboxyl group). Is more preferable.
Furthermore, the ink composition preferably contains a polymer-coated pigment in which at least a part of the pigment surface is coated with a polymer dispersant. Furthermore, the ink composition particularly preferably includes a polymer-coated pigment in which at least a part of the pigment surface is coated with a polymer dispersant having a carboxyl group. Furthermore, the ink composition particularly preferably contains a water-insoluble polymer-coated pigment in which at least a part of the pigment surface is coated with a polymer dispersant having a carboxyl group, from the viewpoint of cohesiveness.

The average particle size of the pigment in the dispersed state (for example, the average particle size of the polymer-coated pigment) is preferably 10 nm to 200 nm, more preferably 10 nm to 150 nm, and even more preferably 10 nm to 100 nm. When the average particle size is 200 nm or less, the color reproducibility is good, and the droplet ejection characteristics when droplets are ejected by the ink jet method are good. When the average particle size is 10 nm or more, light resistance is improved. Further, the particle size distribution of the color material is not particularly limited, and may be either a wide particle size distribution or a monodisperse particle size distribution. Two or more color materials having a monodispersed particle size distribution may be mixed and used. Here, the average particle diameter of the pigment in the dispersed state indicates the average particle diameter in the ink state, but the same applies to the so-called concentrated ink dispersion in the previous stage before the ink is formed.
The average particle size of the pigment in the dispersed state is determined in the same manner as the average particle size and particle size distribution of the polymer particles described above.

You may use a pigment individually by 1 type or in combination of 2 or more types.
The content of the pigment in the ink composition is preferably 1% by mass to 20% by mass and more preferably 2% by mass to 10% by mass with respect to the ink composition from the viewpoint of image density.

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

<Surfactant>
The ink composition in the present invention can contain at least one surfactant as required. The surfactant can be used as a surface tension adjusting agent, for example.
As the surfactant, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactants, cationic surfactants, amphoteric surfactants, nonions Either a surfactant or a betaine surfactant can be used. Further, the above water-soluble polymer (polymer dispersing agent) may be used as a surfactant.

In the present invention, a nonionic surfactant is preferable from the viewpoint of suppressing ink droplet ejection interference, and an acetylene glycol derivative (acetylene glycol surfactant) is more preferable.
Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4, An alkylene oxide adduct of 7-diol can be used, and at least one selected from these is preferable. Examples of commercially available products of these compounds include E series such as Olphine E1010 manufactured by Nissin Chemical Industry Co., Ltd.
As the surfactant other than the acetylene glycol surfactant, a fluorine surfactant is preferable. Examples of the fluorine surfactant include an anionic surfactant, a nonionic surfactant, and a betaine surfactant, and among these, an anionic surfactant is more preferable. Examples of anionic surfactants include Capstone FS-63, Capstone FS-61 (manufactured by Dupont), Footage 100, Footent 110, Footent 150 (manufactured by Neos), CHEMGUARD S-760P (Chemguard) Inc.).

When the surfactant (surface tension adjusting agent) is contained in the ink composition, the surfactant has a surface tension of 20 mN / m to 60 mN from the viewpoint of satisfactorily discharging the ink composition by an ink jet method. It is preferable to contain an amount that can be adjusted to / m, more preferably 20 mN / m to 45 mN / m, and even more preferably 25 mN / m to 40 mN / m from the viewpoint of surface tension.
Here, the surface tension of the ink composition refers to a value measured using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) at a liquid temperature of 25 ° C.

  When the ink composition of the present invention contains a surfactant, the specific amount of the surfactant is not particularly limited, but is preferably 0.1% by mass or more, more preferably based on the total amount of the ink composition. It is 0.1-10 mass%, More preferably, it is 0.2-3 mass%.

<Water-soluble polymer compound>
The ink composition in the present invention preferably contains at least one water-soluble polymer compound as necessary. The water-soluble polymer compound is not particularly limited, and known water-soluble polymer compounds such as polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, and polyethylene glycol can be used.
Further, as the water-soluble polymer compound, a specific polymer compound that may be contained in a treatment liquid described later, or a water-soluble polymer compound described in paragraphs 0026 to 0080 of JP2013-001854A is also suitable. is there.

<Antifoaming agent>
The ink composition of the present invention may contain at least one antifoaming agent as necessary.
Examples of the antifoaming agent include silicone compounds (silicone defoaming agents) and pluronic compounds (pluronic defoaming agents). Among these, silicone antifoaming agents are preferable.
As the silicone-based antifoaming agent, a silicone-based antifoaming agent having a polysiloxane structure is preferable.

A commercial item can be used as an antifoamer.
Examples of commercially available products include BYK-012, 017, 021, 022, 024, 025, 038, 094 (above, manufactured by Big Chemie Japan Co., Ltd.), KS-537, KS-604, KM-72F (above, Shin-Etsu Chemical). Kogyo Co., Ltd.), TSA-739 (Momentive Performance Materials Japan GK), Olfin AF104 (Nisshin Chemical Co., Ltd.), and the like.
Among these, BYK-017, 021, 022, 024, 025, 094, KS-537, KS-604, KM-72F, and TSA-739, which are silicone-based antifoaming agents, are preferable. In view of this, BYK-024 is most preferred.

  When the ink composition of the present invention contains an antifoaming agent, the content of the antifoaming agent is preferably 0.0001% by mass to 1% by mass, and 0.001% by mass to 0.00% by mass with respect to the total amount of the ink composition. 1% by mass is more preferable.

<Colloidal silica>
The ink composition of the present invention may contain colloidal silica as necessary.
Thereby, the stability at the time of continuous discharge of ink can be improved more.
Colloidal silica is a colloid composed of fine particles of inorganic oxide containing silicon having an average particle size of several hundred nm or less. Colloidal silica contains silicon dioxide (including hydrates thereof) as a main component, and may contain aluminate (sodium aluminate, potassium aluminate, etc.) as a minor component.
In addition, colloidal silica may contain inorganic salts such as sodium hydroxide, potassium hydroxide, lithium hydroxide and ammonium hydroxide, and organic salts such as tetramethylammonium hydroxide. These inorganic salts and organic salts act, for example, as colloid stabilizers.
About colloidal silica, the description of Paragraphs 0043-0050 of JP, 2011-202117, A can be referred to suitably, for example.
Moreover, the ink composition of the present invention may contain an alkali metal silicate salt instead of or in addition to colloidal silica, if necessary. Regarding the alkali metal silicate, the description in paragraphs 0052 to 0056 of JP-A-2011-202117 can be appropriately referred to.

  When the ink composition of the present invention contains colloidal silica, the content of colloidal silica is preferably 0.0001% by mass to 10% by mass, and 0.01% by mass to 3% by mass with respect to the total amount of the ink composition. More preferably, 0.02 mass% to 0.5 mass% is still more preferable, and 0.03 mass% to 0.3 mass% is particularly preferable.

<PH adjuster>
The ink composition of the present invention may contain at least one pH adjuster as necessary.
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.
When the ink composition of the present invention contains a pH adjuster, the content of the pH adjuster is preferably such that the pH of the ink composition is 5 to 10 (more preferably 8.0 to 9.5).

<Other ingredients>
The ink composition of the present invention may contain other components as necessary.
Other components include, for example, polymerization inhibitors, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, anti-fungal agents, viscosity modifiers, and dispersion stabilizers. And known additives such as rust preventives and chelating agents.

In order to suppress bleeding by acid aggregation and obtain high resolution, the ink composition of the present invention is preferably basic, and from the viewpoint of high-temperature stability of the ink, it is preferably near neutral.
Specifically, the liquidity (pH) of the ink composition is preferably pH 5 to pH 10. Further, the ink composition is more preferably pH 8.0 to pH 9.5. Moreover,
From the viewpoint of suppressing the load on the member used for image formation, the ink composition preferably has a pH of less than 9.5.

  Further, the viscosity of the ink composition of the present invention is not particularly limited, but from the viewpoint of ejection stability from the nozzle, the viscosity at a liquid temperature of 30 ° C. is 3.5 mPa · s to 6.5 mPa · s. Preferably, 4.0 mPa · s to 6.0 mPa · s is more preferable.

≪Ink set≫
The ink set of the present invention has the above-described ink composition of the present invention and a treatment liquid containing an aggregating component that forms an aggregate when contacted with the ink composition.
Since the ink composition of the present invention is used in the ink set of the present invention, the ink composition is excellent in high temperature aging stability and excellent in abrasion resistance of the formed image.
In particular, the ink set of the present invention has a treatment liquid, so that the abrasion resistance of the image is remarkably improved.
The details of the ink composition are as described above.

<Processing liquid>
Hereinafter, the treatment liquid will be described in detail.
When the treatment liquid applied to the recording medium comes into contact with the ink composition, the dispersion liquid such as pigments and wax particles (and polymer particles that may be used as needed) in the ink composition is aggregated, An image is fixed on a recording medium. The treatment liquid contains at least an aggregating component for aggregating the components in the ink composition, may further contain a polymerization initiator, and may be constituted by using other components as necessary. In addition, by using the treatment liquid together with the ink composition, it is possible to increase the speed of ink jet recording, and an image with excellent density and resolution (for example, reproducibility of fine lines and fine portions) can be obtained even if high speed recording is performed.

(Aggregating component)
The treatment liquid contains at least one aggregation component.
The aggregation component may be a compound capable of changing the pH of the ink composition, a polyvalent metal salt, or a cationic polymer having a quaternary or tertiary amine such as polyallylamines. Also good. In the present invention, from the viewpoint of cohesiveness of the ink composition, a compound capable of changing the pH of the ink composition is preferable, and a compound capable of lowering the pH of the ink composition is more preferable.

Examples of the compound that can lower the pH of the ink composition include acidic substances.
Examples of acidic substances include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, polyacrylic acid, acetic acid, glycolic acid, oxalic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid. Acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, or derivatives of these compounds, or These salts etc. are mentioned suitably.
An acidic substance may be used individually by 1 type, and may use 2 or more types together.

When the treatment liquid in the present invention contains an acidic substance, the pH (25 ° C.) of the treatment liquid is preferably 6 or less, more preferably 4 or less. Especially, pH (25 degreeC) has the preferable range of 0-3, Most preferably, pH is 0.2-2. At this time, the pH (25 ° C.) of the ink composition is preferably 7.5 or more (more preferably 8.0 or more).
Above all, from the viewpoint of image density, resolution, and speedup of inkjet recording, the pH (25 ° C.) of the ink composition is 8.0 or more, and the pH (25 ° C.) of the treatment liquid is 0.2-2. Some cases are preferred.

  Among them, the aggregation component in the present invention is preferably an acidic substance having high water solubility, preferably an organic acid, more preferably a divalent or higher valent organic acid in terms of enhancing the aggregation property and fixing the entire ink. Above-mentioned trivalent or less acidic substances are particularly preferred. The organic acid having a valence of 2 or more is preferably an organic acid having a first pKa of 3.5 or less, more preferably 3.0 or less. Specific examples include phosphoric acid, oxalic acid, malonic acid, malic acid, citric acid, and the like.

  As for the polyvalent metal salt and the cationic polymer, for example, the polyvalent metal salt and the cationic polymer described in paragraphs 0155 to 0156 of JP2011-042150A can be used.

The aggregating components can be used singly or in combination of two or more.
The content of the aggregation component for aggregating the ink composition in the treatment liquid is preferably 1 to 50% by mass, more preferably 3 to 45% by mass, and still more preferably 5 to 40% by mass.

(Water-soluble polymer compound)
The treatment liquid preferably contains at least one water-soluble polymer compound.
The water-soluble polymer compound is not particularly limited, and known water-soluble polymer compounds such as polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, and polyethylene glycol can be used.
As the water-soluble polymer compound, a specific polymer compound described later and water-soluble polymer compounds described in paragraphs 0026 to 0080 of JP2013-001854A are also suitable.

  Although there is no limitation in particular in the weight average molecular weight of a water-soluble high molecular compound, For example, it can be set as 10000-100,000, Preferably it is 20000-80000, More preferably, it is 30000-80000.

In addition, the content of the water-soluble polymer compound in the treatment liquid in the present invention is not particularly limited, but is preferably 0.1% by mass to 10% by mass, and preferably 0.1% by mass to 4 mass% is more preferable, 0.1 mass%-2 mass% is still more preferable, and 0.1 mass%-1 mass% is especially preferable.
When the content is 0.1% by mass or more, the spreading of ink droplets can be further promoted, and when the content is 10% by mass or less, thickening of the treatment liquid can be further suppressed. Moreover, if the said content is 10 mass% or less, the application | coating nonuniformity of the process liquid resulting from the bubble in a process liquid can be suppressed more.

As the water-soluble polymer compound, a polymer compound containing a hydrophilic structural unit having an ionic group (preferably an anionic group) (hereinafter also referred to as “specific polymer compound”) is preferable. Thereby, the spreading of the ink droplets applied to the recording medium can be further promoted, and the roughness of the image is further suppressed.
Examples of the ionic group in the specific polymer compound include a carboxyl group, a sulfonic acid group, a phosphoric acid group, a boronic acid group, an amino group, an ammonium group, and salts thereof. Among them, preferred is a carboxyl group, a sulfonic acid group, a phosphoric acid group, or a salt thereof, more preferred is a carboxyl group, a sulfonic acid group, or a salt thereof, and still more preferred is a sulfonic acid group or a salt thereof. Salt.
The hydrophilic structural unit having an ionic group (preferably an anionic group) is preferably a structural unit derived from a (meth) acrylamide compound having an ionic group (preferably an anionic group).
The content of the hydrophilic structural unit having an ionic group (preferably an anionic group) in the water-soluble polymer compound is, for example, 10 to 100% by mass in the total mass of the water-soluble polymer compound. It is preferably 10 to 90% by mass, more preferably 10 to 70% by mass, further preferably 10 to 50% by mass, and particularly preferably 20 to 40% by mass.

The specific polymer compound includes at least one hydrophobic structural unit in addition to at least one hydrophilic structural unit having the above-described ionic group (preferably an anionic group, particularly preferably a sulfonic acid group). Is more preferable. By including the hydrophobic structural unit, the specific polymer compound is more likely to be present on the surface of the treatment liquid, so that the spread of the ink droplets applied to the recording medium is further promoted, and the roughness of the image is further suppressed.
As the hydrophobic structural unit, a structural unit derived from (meth) acrylic acid ester (preferably, alkyl ester having 1 to 4 carbon atoms of (meth) acrylic acid) is preferable.

  Content of the hydrophobic structural unit in a specific high molecular compound can be 10-90 mass% in the total mass of a specific high molecular compound, for example, it is preferable that it is 30-90 mass%, 50-90 It is more preferable that it is mass%, and it is especially preferable that it is 60-80 mass%.

(water)
The treatment liquid can be configured to contain water.
Although there is no restriction | limiting in particular in content of water, The range of 10-99 mass% is preferable, More preferably, it is 50-90 mass%, More preferably, it is 60-80 mass%.

(Organic solvent)
The treatment liquid preferably contains at least one selected from organic solvents.
As the organic solvent, the same water-soluble solvent that may be contained in the ink composition can be used. Among these, from the viewpoint of curling suppression, polyalkylene glycol or a derivative thereof is preferable. Diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, dipropylene glycol, tripropylene glycol monoalkyl ether, polyoxypropylene glyceryl ether, polyoxypropylene More preferably, it is at least one selected from oxyethylene polyoxypropylene glycol.
The content of the organic solvent in the treatment liquid is not particularly limited, but from the viewpoint of curling suppression, it is preferably 1 to 30% by mass, and preferably 5 to 15% by mass with respect to the entire treatment liquid. More preferred.

(Defoamer)
The treatment liquid may contain at least one antifoaming agent as necessary.
Examples of the antifoaming agent that can be contained in the treatment liquid include the same antifoaming agents that can be contained in the ink composition.
When the processing liquid contains an antifoaming agent, the content of the antifoaming agent is preferably 0.0001% by mass to 1% by mass, and 0.001% by mass to 0.1% by mass with respect to the total amount of the processing liquid. More preferred.

(Polymerization initiator)
The treatment liquid may contain at least one polymerization initiator that is contained in the ink composition and that initiates polymerization of the polymerizable compound in the ink composition by active energy rays. A polymerization initiator can be used individually by 1 type or in mixture of 2 or more types or with a sensitizer.
As in the case of the ink composition, the polymerization initiator used in the treatment liquid can be appropriately selected from compounds that can initiate the polymerization reaction of the polymerizable compound by active energy rays. As an example of a polymerization initiator, the polymerization initiator (for example, photoinitiator etc.) which generate | occur | produces active species (a radical, an acid, a base, etc.) with radiation or light, or an electron beam is mentioned.
Details of the polymerization initiator and the like are as described in the section of the ink composition.

  Further, the processing liquid may further contain other additives as other components within a range not impairing the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, anti-foaming agents. Well-known additives, such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, a chelating agent, are mentioned.

The viscosity of the treatment liquid is not particularly limited, but from the viewpoint of the aggregation rate of the ink composition, the viscosity at a liquid temperature of 25 ° C. is preferably 1 mPa · s to 30 mPa · s, and 1 mPa · s to 20 mPa. -S is more preferable, 2 mPa · s to 15 mPa · s is further preferable, and 2 mPa · s to 10 mPa · s is particularly preferable.
The surface tension of the treatment liquid is not particularly limited, but is preferably 20 mN / m to 60 mN / m and more preferably 20 mN / m to 50 mN / m from the viewpoint of the aggregation rate of the ink composition. Preferably, it is more preferably 25 mN / m to 45 mN / m.

≪Image formation method≫
The image forming method of the present invention includes an ink application process for forming an image by applying the above-described ink composition of the present invention to a recording medium by an inkjet method.
In the image forming method of the present invention, since the ink composition of the present invention is used, a fine image having good abrasion resistance can be formed even when the ink composition aged in a high temperature environment is used. .

<Ink application process>
In the ink application step, the ink composition of the present invention described above is applied to a recording medium by an ink jet method.
In this step, the ink composition can be selectively applied onto the recording medium, and a desired visible image can be formed. The details of the ink composition, such as details and preferred embodiments of the ink composition, are as described above in the description of the ink composition.

  In the image formation by the ink jet method, by applying energy, the ink composition described above is ejected onto a desired recording medium to form a colored image. As a preferable inkjet method for the present invention, the method described in paragraphs 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 ejects ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezoelectric element, An acoustic ink jet system that converts an electrical signal into an acoustic beam, irradiates the ink with ink, and ejects the ink using radiation pressure, and a thermal ink jet that forms bubbles by heating the ink and uses the generated pressure (bubble jet (registered) Trademark)) method or the like. As an ink jet method, in particular, the method described in Japanese Patent Application Laid-Open No. Sho 54-59936 causes an abrupt volume change of the ink subjected to the action of thermal energy, and the ink is ejected from the nozzle by the action force due to this state change. Ink jet method can be used effectively.
The inkjet method uses 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 used is included.

  The ink ejection method from the ink-jet head in the ink-jet method uses a short serial head, a shuttle method that performs recording while scanning the head in the width direction of the recording medium, and the entire area of one side of the recording medium. There is a line system using a line head in which recording elements are arranged. In the line method, an image can be recorded on the entire surface of the recording medium by scanning the recording medium in a direction crossing the arrangement direction of the recording elements, and a carriage system such as a carriage for scanning a short head is not necessary. Further, since complicated scanning control of the carriage movement and the recording medium is not required, and only the recording medium is moved, the recording speed can be increased as compared with the shuttle system. The image forming method of the present invention can be applied to any of these, but generally, when applied to a line system that does not use a dummy jet, the effect of improving ejection accuracy and image abrasion resistance is great.

  The amount of ink droplets ejected from the inkjet head is preferably 1 to 10 pl (picoliter) and more preferably 1.5 to 6 pl from the viewpoint of obtaining a high-definition image. In addition, from the viewpoint of improving the unevenness of the image and the continuous gradation, it is also effective to discharge different amounts of liquids in combination, and even in such a case, the present invention can be suitably used.

<Processing liquid application process>
The image forming method of the present invention preferably further includes a treatment liquid application step of applying a treatment liquid containing an aggregation component that forms an aggregate when contacted with the ink composition to the recording medium.
Thereby, the abrasion resistance of the image is further improved, and the image unevenness is further reduced.

  In the treatment liquid application step, a treatment liquid containing an aggregating component that aggregates the components in the ink composition is applied to the recording medium, and the treatment liquid is brought into contact with the ink composition to form an image. In this case, dispersed particles including pigments and wax particles (and polymer particles that may be used as needed) in the ink composition aggregate to fix the image on the recording medium. The treatment liquid contains at least an aggregating component, and details and preferred embodiments of each component are as described above.

  The treatment liquid can be applied by applying a known method such as a coating method, an ink jet method, or an immersion method. As a coating method, a known coating method using a bar coater, an extrusion die coater, an air doctor coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater or the like can be used. The details of the inkjet method are as described above.

The treatment liquid application step may be provided either before or after the ink application step using the ink composition. In the present invention, an embodiment in which an ink application process is provided after the treatment liquid application process is preferable.
Specifically, before applying the ink composition onto the recording medium, a treatment liquid is applied in advance to agglomerate the components (the above-mentioned dispersed particles) in the ink composition, and then applied onto the recording medium. An embodiment in which an ink composition is applied so as to come into contact with the treated liquid and imaged is preferable. Thereby, inkjet recording can be speeded up, and an image with high density and resolution can be obtained even at high speed recording.

The application amount of the treatment liquid is not particularly limited as long as the ink composition can be aggregated. However, it is preferable that the application amount of the aggregation component is 0.1 g / m ² or more. Especially, the quantity from which the provision amount of an aggregation component will be 0.2-0.7 g / m < ² > is preferable. When the application amount of the aggregating component is 0.1 g / m ² or more, good high-speed aggregating property can be maintained according to various usage forms of the ink composition. Moreover, it is preferable that the application amount of the aggregating component is 0.7 g / m ² or less from the viewpoint of not affecting the surface properties of the applied recording medium (change in gloss, etc.).

  In the present invention, an ink application step is provided after the treatment liquid application step, and the treatment liquid on the recording medium is heated and dried after the treatment liquid is applied on the recording medium and before the ink composition is applied. It is preferable to further provide a heat drying step. By heating and drying the treatment liquid in advance before the ink application step, ink colorability such as bleeding prevention is improved, and a visible image with good color density and hue can be recorded.

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

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

  As the recording medium, commercially available media can be used. For example, “OK Prince Quality” manufactured by Oji Paper Co., Ltd., “Shiraoi” manufactured by Nippon Paper Industries Co., Ltd., and Nippon Paper Industries Co., Ltd. Fine paper (A) such as “New NPI Fine” manufactured by Oji Paper Co., Ltd., “OK Everlight Coat” manufactured by Oji Paper Co., Ltd., and “Aurora S” manufactured by Nippon Paper Industries Co., Ltd., Oji Paper Co., Ltd. Lightweight coated paper (A3) such as “OK Coat L” manufactured by Nippon Paper Industries Co., Ltd. and “Aurora L” manufactured by Nippon Paper Industries Co., Ltd. “OK Top Coat +” manufactured by Oji Paper Co., Ltd. and Nippon Paper Industries Co., Ltd. Coated paper (A2, B2) such as “Aurora Coat” manufactured by Oji Paper Co., Ltd. Art paper (A1) such as “OK Kanto +” manufactured by Oji Paper Co., Ltd. and “Tokuhishi Art” manufactured by Mitsubishi Paper Industries Co., Ltd. Can be mentioned. It is also possible to use various photographic papers for ink jet recording.

  Among the recording media, so-called coated paper used for general offset printing is preferable. The coated paper is obtained by applying a coating material to the surface of high-quality paper, neutral paper, or the like that is mainly surface-treated with cellulose as a main component and is not surface-treated. The coated paper is liable to cause quality problems such as glossiness and scratch resistance of the image in normal aqueous inkjet image formation. An image having good rubbing properties can be obtained. In particular, a coated paper having a base paper and a coating layer containing an inorganic pigment is preferably used, and a coated paper having a base paper and a coating layer containing at least one of kaolin and calcium bicarbonate is more preferably used. Specifically, art paper, coated paper, lightweight coated paper, or finely coated paper is more preferable.

<Inkjet recording apparatus>
The image forming apparatus that can be used in the image forming method of the present invention is not particularly limited, and is publicly known as described in JP 2010-830221 A, JP 2009-234221 A, JP 10-175315 A, and the like. The image forming apparatus can be used.
The image forming apparatus preferably includes an active energy ray (for example, ultraviolet ray) irradiation unit. For the configuration of other means including the active energy ray irradiation means, for example, a known configuration described in JP 2011-184628 A can be referred to as appropriate.

Hereinafter, an example of an image forming apparatus that can be used in the image forming method of the present invention will be described with reference to FIG.
Next, an example of an ink jet recording apparatus suitable for carrying out the image forming method of the present invention will be specifically described with reference to FIG.
FIG. 1 is a schematic configuration diagram illustrating a configuration example of the entire inkjet recording apparatus.

  As shown in FIG. 1, the ink jet recording apparatus includes an anilox roller 20 and a coating roller 22 in contact with the anilox roller 20 as roller materials for coating the processing liquid sequentially in the recording medium conveyance direction (arrow direction in the figure). The provided treatment liquid application unit 12, the treatment liquid drying zone 13 provided with a heating means (not shown) for drying the applied treatment liquid, the ink ejection unit 14 that ejects various ink compositions, and the ejected ink An ink drying zone 15 for drying the composition is provided. Further, an ultraviolet irradiation unit 16 including an ultraviolet irradiation lamp 16S is disposed on the downstream side of the ink drying zone 15 in the conveyance direction of the recording medium.

  The recording medium supplied to the ink jet recording apparatus includes a processing liquid application unit 12, a processing liquid drying zone 13, and an ink discharging unit by a conveying roller from a paper feeding unit that feeds the recording medium from a case loaded with the recording medium. 14, the ink drying zone 15, and the ultraviolet irradiation unit 16 are sequentially sent and accumulated in the accumulation unit. In addition to the method using a conveyance roller, the conveyance may be performed by a drum conveyance method using a drum-shaped member, a belt conveyance method, a stage conveyance method using a stage, or the like.

  Among the plurality of transport rollers, at least one roller may be a driving roller to which the power of a motor (not shown) is transmitted. By rotating a driving roller rotated by a motor at a constant speed, the recording medium is conveyed in a predetermined direction by a predetermined conveyance amount.

The treatment liquid application unit 12 is provided with an anilox roller 20 that is disposed by immersing a part of the treatment liquid in a storage dish in which the treatment liquid is stored, and an application roller 22 that is in contact with the anilox roller 20. The anilox roller 20 is a roller material for supplying a predetermined amount of processing liquid to the application roller 22 arranged to face the recording surface of the recording medium. The treatment liquid is uniformly applied onto the recording medium by the application roller 22 supplied with an appropriate amount from the anilox roller 20.
The application roller 22 is configured to be able to convey a recording medium in a pair with the opposing roller 24, and the recording medium passes between the application roller 22 and the opposing roller 24 and is sent to the treatment liquid drying zone 13.

  A treatment liquid drying zone 13 is disposed downstream of the treatment liquid application unit 12 in the recording medium conveyance direction. The treatment liquid drying zone 13 can be configured by using a known heating means such as a heater, an air blowing means using air blowing such as a dryer, or a combination of these. The heating means is a method of installing a heating element such as a heater on the side opposite to the treatment liquid application surface of the recording medium (for example, below the conveyance mechanism that carries the recording medium when conveying the recording medium automatically), Examples include a method of applying warm air or hot air to the treatment liquid application surface of the recording medium, a heating method using an infrared heater, and the like.

Also, since the surface temperature of the recording medium varies depending on the type (material, thickness, etc.) of the recording medium and the environmental temperature, the surface temperature of the recording medium measured by the measuring unit that measures the surface temperature of the recording medium and the measuring unit It is preferable to apply the treatment liquid while providing a control mechanism that feeds back the value to the heating control unit. As a measurement part which measures the surface temperature of a recording medium, a contact or non-contact thermometer is preferable.
Further, the solvent may be removed using a solvent removal roller or the like. As another embodiment, a method of removing excess solvent from the recording medium with an air knife is also used.

  The ink discharge unit 14 is disposed downstream of the treatment liquid drying zone 13 in the recording medium conveyance direction. The ink discharge section 14 includes a recording head (ink discharge head) 30K connected to each of the ink storage sections that store black (K), cyan (C), magenta (M), and yellow (Y) color inks. 30C, 30M, and 30Y are arranged. Each ink storage section (not shown) stores an ink composition containing a pigment corresponding to each hue, polymer particles, a water-soluble solvent, and water. The heads 30K, 30C, 30M, and 30Y are supplied. Further, as shown in FIG. 1, a recording head 30A for spot color ink discharge is provided on the downstream side in the transport direction of the ink discharge heads 30K, 30C, 30M, and 30Y so that spot color ink can be discharged as needed. 30B can be further provided.

  The ink ejection heads 30K, 30C, 30M, and 30Y each eject ink corresponding to an image from ejection nozzles arranged to face the recording surface of the recording medium. Thus, each color ink is applied on the recording surface of the recording medium, and a color image is recorded.

  The ink discharge heads 30K, 30C, 30M, 30Y, 30A, and 30B are all full in which a large number of discharge ports (nozzles) are arranged over the maximum recording width (maximum recording width) of an image recorded on the recording medium. It is a line head. Compared to the serial type in which recording is performed while reciprocating a short shuttle head in the width direction of the recording medium (direction perpendicular to the conveying direction on the recording medium conveying surface), it is possible to record an image on the recording medium at a higher speed. it can. In the present invention, either a serial type recording or a system capable of relatively high speed recording, for example, a single pass system in which one line is formed by one scan may be employed. According to this image recording method, a high-quality image with high reproducibility can be obtained even with the single pass method.

  Here, the ink ejection heads 30K, 30C, 30M, 30Y, 30A, and 30B all have the same structure.

  The application amount of the treatment liquid and the application amount of the ink composition are preferably adjusted as necessary. For example, the application amount of the treatment liquid may be changed according to the recording medium in order to adjust the physical properties such as the viscoelasticity of the aggregate formed by mixing the treatment liquid and the ink composition.

  The ink drying zone 15 is disposed downstream of the ink discharge unit 14 in the recording medium conveyance direction. The ink drying zone 15 can be configured in the same manner as the treatment liquid drying zone 13.

The ultraviolet irradiation unit 16 is arranged further downstream in the recording medium conveyance direction of the ink drying zone 15, and is irradiated with ultraviolet rays by an ultraviolet irradiation lamp 16S provided in the ultraviolet irradiation unit 16, and in the image after image drying. The monomer component is polymerized and cured. The ultraviolet irradiation lamp 16S irradiates the entire recording surface with a lamp disposed opposite to the recording surface of the recording medium, so that the entire image can be cured. The ultraviolet irradiation unit 16 is not limited to the ultraviolet irradiation lamp 16S, and a halogen lamp, a high-pressure mercury lamp, a laser, an LED, an electron beam irradiation device, or the like can also be employed.
The ultraviolet irradiation unit 16 may be installed either before or after the ink drying zone 15, or may be installed both before and after the ink drying zone 15.

  Further, in the ink jet recording apparatus, a heating unit that performs a heat treatment on the recording medium can be arranged in a conveyance path from the paper feeding unit to the stacking unit. For example, the temperature of the recording medium is raised to a desired temperature by disposing a heating unit at a desired position such as the upstream side of the treatment liquid drying zone 13 or between the ink discharge unit 14 and the ink drying zone 15. Thus, drying and fixing can be effectively performed.

  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.

<Preparation of Polymer Dispersant 1 Solution>
In a reaction vessel, 6 parts of styrene, 11 parts of stearyl methacrylate, 4 parts of styrene macromer AS-6 (manufactured by Toagosei Co., Ltd.), 5 parts of Bremer PP-500 (manufactured by NOF Corporation), 5 parts of methacrylic acid, 2 -0.05 part of mercaptoethanol and 24 parts of methyl ethyl ketone were added to prepare a mixed solution. Meanwhile, in a dropping funnel, 14 parts of styrene, 24 parts of stearyl methacrylate, 9 parts of styrene macromer AS-6 (manufactured by Toagosei Co., Ltd.), 9 parts of Blenmer PP-500 (manufactured by NOF Corporation), 10 parts of methacrylic acid 2-mercaptoethanol (0.13 parts), methyl ethyl ketone (56 parts), and 2,2′-azobis (2,4-dimethylvaleronitrile) (1.2 parts) were added to prepare a mixed solution.
Thereafter, the mixed solution in the reaction vessel was heated to 75 ° C. with stirring in a nitrogen atmosphere, and the mixed solution in the dropping funnel was gradually dropped over 1 hour. 2 hours after the completion of the dropwise addition, a solution prepared by dissolving 1.2 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) in 12 parts of methyl ethyl ketone was added dropwise over 3 hours, and further at 75 ° C. for 2 hours. Aged at 80 ° C. for 2 hours to obtain a polymer dispersant 1 solution.

  About a part of the obtained polymer dispersant 1 solution, the solid content was isolated by removing the solvent. The obtained solid content was diluted to 0.1% with tetrahydrofuran, and TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, TSKgeL SuperHZ2000 (high performance GPC (gel permeation chromatography) HLC-8220GPC (manufactured by Tosoh Corporation)) Three Tosoh Corporation) were connected in series, and the weight average molecular weight was measured. The measured weight average molecular weight was 25,000 in terms of polystyrene. The acid value of the polymer determined by the method described in JIS standard (JIS K0070: 1992) was 99 mgKOH / g.

<Preparation of pigment dispersion M>
5.0 g of the obtained polymer dispersant 1 solution in terms of solid content, 10.0 g of magenta pigment (Pigment Red 122, manufactured by Dainichi Seika Co., Ltd.), 40.0 g of methyl ethyl ketone, 1 mol / L (liters; the same applies hereinafter) 8.0 g of sodium hydroxide and 82.0 g of ion-exchanged water were supplied to a vessel together with 300 g of 0.1 mm zirconia beads, and dispersed at 1000 rpm for 6 hours using a ready mill disperser (manufactured by Imex). The obtained dispersion was concentrated under reduced pressure using an evaporator until methyl ethyl ketone could be sufficiently distilled off, and further concentrated until the pigment concentration became 12% to prepare a pigment dispersion M of a polymer-coated magenta pigment.
The volume average particle size (secondary particles) of the obtained pigment dispersion M was measured using a dynamic light scattering method using a Microtrac particle size distribution analyzer (trade name Version 10.1.2-211BH, manufactured by Nikkiso Co., Ltd.). Was 84 nm.

<Preparation of pigment dispersion Y>
In the preparation of the pigment dispersion M, the same procedure as in the preparation of the pigment dispersion M was performed except that Irgalite Yellow GS (Pigment Yellow 74, manufactured by BASF Japan) was used instead of Pigment Red 122 used as the pigment. A pigment dispersion Y of polymer-coated yellow pigment was obtained. The volume average particle diameter (secondary particles) of the pigment dispersion Y measured in the same manner as in the pigment dispersion M was 75 nm.

<Preparation of pigment dispersion K>
In the preparation of the pigment dispersion M, the same procedure as in the preparation of the pigment dispersion M was performed except that carbon black MA-100 (manufactured by Mitsubishi Chemical Corporation; black pigment) was used instead of Pigment Red 122 used as the pigment. Thus, a pigment dispersion K of the polymer-coated black pigment was obtained. The volume average particle diameter (secondary particles) of the pigment dispersion K measured in the same manner as in the pigment dispersion M was 80 nm.

<Preparation of pigment dispersion C>
As pigment dispersion C, CABO-JET250C (Pigment Blue 15: 4 (PB15: 4); cyan pigment dispersion manufactured by CABOT Co., Ltd.) was prepared. The pigment dispersion C is a pigment dispersion of a polymer-coated cyan pigment in which PB15: 4 is coated with a polymer. The volume average particle diameter (secondary particles) of pigment dispersion C measured in the same manner as pigment dispersion M was 110 nm.

<Synthesis of polymerizable compound>
A polymerizable compound a, a polymerizable compound b, and a polymerizable compound c, which are exemplary compounds of the (meth) acrylamide compound represented by the general formula (1), were respectively synthesized.
These syntheses were carried out according to the method described in paragraphs 0123 to 0128 of JP2013-18846A.

<Synthesis of self-dispersing polymer particles P-1 (polymer particles)>
360.0 g of methyl ethyl ketone was charged into a 2-liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, and the temperature was raised to 75 ° C. Thereafter, while maintaining the temperature in the flask at 75 ° C., 151.2 g of benzyl methacrylate, 172.8 g of methyl methacrylate, 36.0 g of methacrylic acid, 72 g of methyl ethyl ketone, and “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) 1 .44 g of the mixed solution was added dropwise at a constant speed so that the addition was completed in 2 hours. After completion of the dropwise addition, a solution composed of 0.72 g of “V-601” and 36.0 g of methyl ethyl ketone was added thereto, stirred at 75 ° C. for 2 hours, and further a solution composed of 0.72 g of “V-601” and 36.0 g of isopropanol. And stirred at 75 ° C. for 2 hours. Thereafter, the temperature was raised to 85 ° C., and stirring was further continued for 2 hours to obtain a polymer solution of a benzyl methacrylate / methyl methacrylate / methacrylic acid (= 42/48/10 [mass ratio]) copolymer.
The weight average molecular weight (Mw) measured in the same manner as described above of the obtained copolymer was 58000 (calculated in terms of polystyrene by gel permeation chromatography (GPC)), and the acid value was 32.6 mgKOH / g. It was.

  Next, 668.3 g of the obtained polymer solution was weighed, 388.3 g of isopropanol and 145.7 ml of 1 mol / L NaOH aqueous solution were added thereto, and the temperature in the reaction vessel was raised to 80 ° C. Next, 720.1 g of distilled water was added dropwise at a rate of 20 ml / min to disperse in water, and then the reaction vessel internal temperature was 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure. Kept. Thereafter, the pressure in the reaction vessel is reduced, and 913.7 g of isopropanol, methyl ethyl ketone, and distilled water are distilled off in total, and the self-dispersing polymer particles P-1 (polymer particles) having a solid content concentration (polymer particle concentration) of 28.0% by mass ) Was obtained.

It was 90 degreeC when the glass transition temperature (Tg) of the said self-dispersing polymer particle P-1 was measured with the following method.
-Measurement of glass transition temperature (Tg)-
An aqueous dispersion of self-dispersing polymer particles having a solid content of 0.5 g was dried under reduced pressure at 50 ° C. for 4 hours to obtain a polymer solid content. Using the obtained polymer solid content, Tg was measured with a differential scanning calorimeter (DSC) EXSTAR 6220 manufactured by SII Nanotechnology. The measurement condition was that a sample amount of 5 mg was sealed in an aluminum pan, and the DSC peak top value of the measurement data at the second temperature increase was defined as Tg under the following temperature profile in a nitrogen atmosphere.
30 ° C to -50 ° C (cooled at 50 ° C / min)
−50 ° C. → 120 ° C. (temperature rising at 20 ° C./min)
120 ° C to -50 ° C (cooled at 50 ° C / min)
−50 ° C. → 120 ° C. (temperature rising at 20 ° C./min)

<Synthesis of water-soluble polymer compound (water-soluble polymer)>
A water-soluble polymer compound (water-soluble polymer 1) used as a component in the treatment liquid was synthesized. This synthesis was performed according to paragraphs 0200 to 0204 and 0229 of JP2013-001854A.
The structure of the water-soluble polymer 1 is shown below.
In the water-soluble polymer 1 shown below, the number on the lower right of each structural unit represents a mass ratio (mass%), and Mw represents a weight average molecular weight.

[Example 1]
As Example 1, an experiment was conducted regarding the type of polymerization initiator, the type of polymerizable compound, and the type of wax in the ink.

≪Experiment number 1≫
As Experiment No. 1, a black ink was prepared, the high-temperature stability over time of the prepared black ink was evaluated, and the abrasion resistance of an image formed using the prepared black ink was evaluated. Details will be described below.

<Preparation of black ink>
Components of the following composition were mixed and coarse particles were removed through a membrane filter (pore size 0.5 μm) to obtain a black ink (ink composition).
The physical properties of the produced black ink were a viscosity of 5.0 mPa · s (30 ° C.), a surface tension of 36.0 mN / m (25 ° C.), and a pH of 8.8 (25 ° C.).
Here, the viscosity, surface tension, and pH are respectively VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD), Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.), and pH meter WM-50EG (manufactured by Kyowa Interface Science Co., Ltd.). Measured using Toa DDK Co., Ltd.

(Black ink composition)
・ Pigment dispersion K: 15.0% by mass
-Pigment dispersion M: 4.0% by mass
-Pigment dispersion C: 4.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)) 12.0% by mass
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 3.0 mass%
・ 2-Pyrrolidone (specific example of water-soluble solvent represented by formula (B)): 5.0% by mass
・ Glycerin (water-soluble solvent): 5.0% by mass
・ Sanix GP250 (Sanyo Chemical Industries; water-soluble solvent): 5.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
Self-dispersing polymer particle P-1: 3.0% by mass
・ Triethanolamine (pH adjuster): 0.3% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd .; polyvinylpyrrolidone)
... 0.2% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd .; wax particles): 1.0% by mass
-Potassium nitrate (viscosity modifier) ... 0.1% by mass
・ 4-HYDROXY-TEMPO (manufactured by EVONIK)… 0.003 mass%
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Total remaining amount of 100% by mass

<Preparation of treatment solution>
The component of the following composition was mixed and the processing liquid was obtained.
The physical properties of the prepared treatment liquid were a viscosity of 2.6 mPa · s (25 ° C.), a surface tension of 41.0 mN / m (25 ° C.), and a pH of 0.7 (25 ° C.).
Here, the viscosity, surface tension, and pH are respectively VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD), Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.), and pH meter WM-50EG (manufactured by Kyowa Interface Science Co., Ltd.). Measured using Toa DDK Co., Ltd.

(Composition of treatment liquid)
・ TPGmME (Tripropylene glycol monomethyl ether) 4.8% by mass
・ DEGmBE (diethylene glycol monobutyl ether) 4.8% by mass
-Malonic acid: 14.0% by mass
・ Malic acid: 7.8% by mass
・ Propanetricarboxylic acid: 3.5% by mass
・ 85 mass% phosphoric acid aqueous solution ... 13.0 mass%
・ The above-mentioned water-soluble polymer 1 0.6 mass%
・ Antifoamer (Momentive Performance Materials Japan TSA-739 (15%); emulsion type silicone antifoam)
… 0.01% by mass as silicone oil
・ Ion-exchanged water: Total remaining amount of 100% by mass

<Image formation>
A GELJET GX5000 printer head manufactured by Ricoh Co., Ltd. was prepared.
This printer head is a line head in which 96 nozzles are arranged.
This printer head was fixedly arranged in an ink jet recording apparatus having the same configuration as the ink jet recording apparatus shown in FIG.
The arrangement at this time was such that the direction in which the 96 nozzles were aligned was inclined by 75.7 ° with respect to the direction orthogonal to the moving direction of the stage of the inkjet apparatus.

  An OK top coat (manufactured by Oji Paper Co., Ltd.) was prepared as a recording medium, and the following treatment liquid application step, drying step, and ink application step were sequentially performed to form (record) an image on the recording medium.

-Treatment liquid application process-
An OK top coat was fixed on a stage movable in a linear direction at 500 mm / second, and each of the treatment liquids obtained above was applied thereto with a wire bar coater so as to be about 1.7 g / m ² .
-Drying process-
At the place where the application of the treatment liquid is completed, drying of the recording medium is started under the condition of 50 ° C. using a dryer after 1.5 seconds from the end of the application of the treatment liquid to the place. The drying was finished 3.5 seconds after the end of the application of the. The drying time at this time is 2 seconds.
-Ink application process-
Within 2 seconds after the drying step, ink ejection was started by the following method.

--- Drip ejection method--
While moving the recording medium at a constant speed in the moving direction of the stage, the black ink prepared above from the printer head is applied with an ink droplet amount of 3.5 pL, an ejection frequency of 24 kHz, a resolution of 1200 dpi × 1200 dpi, and a stage speed of 50 mm / s. A solid image was printed using a line method under the above discharge conditions. The black ink used was deaerated through a deaeration filter and temperature-controlled at 30 ° C.
The solid image immediately after printing was dried at 60 ° C. for 3 seconds, and the solid image after curing was irradiated with UV (ultraviolet rays) to cure the solid image.

Irradiation of the above UV (ultraviolet light) is performed by using a metal halide lamp (maximum irradiation wavelength: 365 nm) manufactured by Eye Graphics Co., Ltd., and controlling the light source power and the conveyance speed to achieve an illuminance of 1.5 W / cm ² (integrated irradiation). (Amount: 0.75 J / cm ² )

<Evaluation of high temperature aging stability (60 ° C. aging stability) of ink composition>
25 g of the black ink (ink composition) obtained above was placed in a 30 ml polybin, and the polybin was stored in Thermocelco set at 60 ° C. for 2 weeks. The viscosity of the ink was measured before and after the storage, and the Δ viscosity was calculated according to the following formula.
Δ viscosity = (ink viscosity after storage at 60 ° C for 2 weeks)-(ink viscosity immediately after ink preparation)

Based on the obtained Δ viscosity, the high temperature aging stability (60 ° C. aging stability) of the ink was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1 below.
The smaller the Δ viscosity, the better the high temperature aging stability of the ink, which is preferable. Further, as the Δ viscosity is larger, the high temperature aging stability of the ink is inferior, and as a result, the ink dischargeability tends to deteriorate.
In the following evaluation criteria, if it is A or B, it is within a practically acceptable range.

-Evaluation criteria for high-temperature stability over time (60 ° C stability over time)-
A: Δ viscosity ≦ 0.3 mPa · s
B: 0.3 mPa · s <Δ viscosity ≦ 0.6 mPa · s
C: 0.6 mPa · s <Δ viscosity ≦ 2 mPa · s
D: Δ viscosity> 2 mPa · s

<Evaluation of abrasion resistance of image>
According to the above <image formation>, a 100% solid image having a width of about 6 mm was recorded on a recording medium.
Immediately thereafter (immediately after curing by UV irradiation), an unrecorded recording medium (the same recording medium used for recording) is superimposed on the recorded solid image (hereinafter also referred to as “recorded image”), and a load of 5 kg. The operation of rubbing 500 reciprocations over / m ² was performed.
After this operation, the scratches on the recorded image and the degree of ink transfer to the recording medium not recorded were visually observed, and the abrasion resistance of the image was evaluated according to the following evaluation criteria.
The evaluation results are shown in Table 1 below.
In the following evaluation criteria, if it is A or B, it is within a practically acceptable range.

-Evaluation criteria for image abrasion resistance-
A: There was no transfer of ink to a recording medium that was not recorded.
B: Scratches are hardly observed in the recorded image, but a slight transfer of ink to the recording medium not recorded is recognized.
C: Slight scratches on the recorded image are recognized, and ink transfer to a recording medium that is not recorded is also observed.
D: The scratch of the recorded image is remarkable, and the transfer of the ink to the recording medium not recorded is also remarkable.

≪Experiment numbers 2-20≫
In Experiment No. 1, the same evaluation as in Experiment No. 1 was performed except that at least one of the type of polymerization initiator, the type of polymerizable compound, and the type of wax was changed as shown in Table 1 below. It was.
The evaluation results are shown in Table 1 below.

Details of the polymerization initiators in Table 1 below are as follows.
-(X) -1: above-mentioned exemplary compound (X) -1 (polymerization initiator represented by general formula (X))
-(X) -2: above-mentioned exemplary compound (X) -2 (polymerization initiator represented by general formula (X))
(X) -11: The aforementioned exemplary compound (X) -11 (polymerization initiator represented by the general formula (X))
Irgacure 2959: Polymerization initiator “Irgacure 2959” manufactured by BASF Japan (compound name: 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one )
ExI-1: a polymerization initiator having the following structure (S-1 described in JP2009-143972A)
ExI-2: Polymerization initiator having the following structure (S-27 described in JP2009-143972A)

In Table 1 below, all of Cellozol 524, Torasol PF60, Polylon L-787, and Polylon P-502 are wax particles made by Chukyo Yushi Co., Ltd., ITOHWAX E-210 and ITOHWAX J-530, All are wax particles made by Ito Oil Co., Ltd. In addition, ester A in Table 1 below is ester A (wax particles) described in paragraph 0254 of JP2011-162692A.
Of these, carnauba wax is cellosol 524.

  As shown in Table 1, an ink containing a polymerization initiator represented by the general formula (X), a polyfunctional (meth) acrylamide type polymerizable compound, and wax particles having a melting point of 40 ° C. or higher and 140 ° C. or lower is used. In the case of the ink, the ink was excellent in stability at 60 ° C. with time, and the formed image was excellent in abrasion resistance.

[Example 2]
As Example 2, an experiment was conducted regarding the type of polymerization initiator and the type of water-soluble solvent.
Specifically, in the ink of Experiment No. 1 of Example 1, at least one of the exemplary compound (X) -1 as a polymerization initiator and 2-pyrrolidone as a water-soluble solvent is the same mass as shown in Table 2 below. Evaluation similar to the experiment number 1 of Example 1 was performed except having changed into.
The evaluation results are shown in Table 2 below.

Details of the types of water-soluble solvents in Table 2 below are as follows.
S-1: 1-hydroxyethyl-2-pyrrolidone (specific example of water-soluble solvent represented by formula (B))
S-2: 1-ethyl-2-pyrrolidone (specific example of water-soluble solvent represented by formula (B))
S-3: 3-n-butoxy-N, N-dimethylpropionamide (specific example of water-soluble solvent represented by formula (A))
S-4: 3-n-propoxy-N, N-dimethylpropionamide (specific example of water-soluble solvent represented by formula (A))
S-5: Tripropylene glycol monomethyl ether

As shown in Table 2, when the water-soluble solvent represented by the general formula (B) is used as the water-soluble solvent (Experiment Nos. 1, 22, and 22), the ink is particularly excellent in stability over time at 60 ° C. It was.
Among these, when 2-pyrrolidone was used as the water-soluble solvent represented by the general formula (B) (Experiment No. 1), the abrasion resistance of the image was particularly excellent.

Example 3
As Example 3, an experiment related to the type and content of the polymerization initiator was performed.
Specifically, in Experiment No. 1 of Example 1, the same evaluation as in Experiment No. 1 of Example 1 was performed except that the type and amount (% by mass) of the polymerization initiator were changed as shown in Table 3 below. It was.
The evaluation results are shown in Table 3 below.

  As shown in Table 3, even when inexpensive Irgacure 2959 is used up to 5.0 mass times that of Exemplified Compound (X) -1, the rubbing resistance of the image and the 60 ° C. stability over time of the ink are preferably maintained. Was confirmed.

Example 4
As Example 4, cyan ink, magenta ink, and yellow ink were prepared (compositions are shown below), and the same evaluation as in Example 1 (black ink) was performed using these inks.
As a result, as in Example 1 (black ink), it was confirmed that the ink was excellent in stability at 60 ° C. with time and image abrasion resistance.

(Composition of cyan ink)
Pigment dispersion C: 20.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)) 12.0% by mass
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 2.0% by mass
・ 2-Pyrrolidone (specific example of water-soluble solvent represented by formula (B)): 5.0% by mass
・ Glycerin (water-soluble solvent): 5.0% by mass
・ Sanix GP250 (Sanyo Chemical Industries; water-soluble solvent): 5.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
Self-dispersing polymer particle P-1: 3.0% by mass
・ Triethanolamine (pH adjuster): 0.3% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd .; polyvinylpyrrolidone)
... 0.2% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd .; wax particles): 1.5% by mass
-Potassium nitrate (viscosity modifier) ... 0.1% by mass
・ 4-HYDROXY-TEMPO (manufactured by EVONIK)… 0.003 mass%
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Remaining amount when 100% by mass as a whole

(Magenta ink composition)
-Pigment dispersion M: 42.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)) 12.0% by mass
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 3.0 mass%
・ 2-Pyrrolidone (specific example of water-soluble solvent represented by formula (B)): 5.0% by mass
・ Glycerin (water-soluble solvent): 5.0% by mass
・ Sanix GP250 (Sanyo Chemical Industries; water-soluble solvent): 5.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
Self-dispersing polymer particle P-1: 3.0% by mass
・ Triethanolamine (pH adjuster): 0.3% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd .; polyvinylpyrrolidone)
... 0.2% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd .; wax particles): 1.0% by mass
-Potassium nitrate (viscosity modifier) ... 0.1% by mass
・ 4-HYDROXY-TEMPO (manufactured by EVONIK)… 0.003 mass%
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Remaining amount when 100% by mass as a whole

(Composition of yellow ink)
Pigment dispersion Y: 35.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)) 10.0 mass%
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 2.0% by mass
・ 2-Pyrrolidone (specific example of water-soluble solvent represented by formula (B)): 5.0% by mass
・ Glycerin (water-soluble solvent): 5.0% by mass
・ Sanix GP250 (Sanyo Chemical Industries; water-soluble solvent): 5.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
Self-dispersing polymer particle P-1: 3.0% by mass
・ Triethanolamine (pH adjuster): 0.3% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd .; polyvinylpyrrolidone)
... 0.2% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd .; wax particles): 1.0% by mass
-Potassium nitrate (viscosity modifier) ... 0.1% by mass
・ 4-HYDROXY-TEMPO (manufactured by EVONIK)… 0.003 mass%
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Remaining amount when 100% by mass as a whole

Example 5
The following ink compositions having a reduced content of the polymerizable compound and the photopolymerization initiator were prepared, and each ink composition was evaluated in the same manner as in Experiment No. 1 of Example 1.
As a result, it was confirmed that the effects of the present invention were observed in each ink composition.
Specifically, the evaluation result of each ink composition was that the ink stability at 60 ° C. with time was “A” and the abrasion resistance was “A” according to the above evaluation criteria.

<Composition of black ink>
・ Pigment dispersion K: 15.0% by mass
-Pigment dispersion M: 4.0% by mass
-Pigment dispersion C: 4.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)): 1.0% by mass
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 0.2% by mass
・ 2-Pyrrolidone: 0.5% by mass
・ Glycerin: 3.0% by mass
・ Propylene glycol (made by ADEKA): 9.0% by mass
・ MFTG (manufactured by Nippon Emulsifier Co., Ltd.) 2.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 0.3% by mass
・ Orphine E1020 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
・ Self-dispersing polymer particles P-1: 8.0% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd.)… 0.2% by mass
・ Urea: 5.0% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd.): 1.5% by mass
・ Potassium nitrate: 0.05% by mass
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
・ Capstone FS-63 (manufactured by Dupont, surfactant): 0.01% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Remaining amount when 100% by mass as a whole

<Cyan ink composition>
Pigment dispersion C: 20.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)): 1.0% by mass
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 0.2% by mass
・ 2-Pyrrolidone: 0.5% by mass
・ Glycerin: 3.0% by mass
・ Propylene glycol (made by ADEKA): 9.0% by mass
・ MFTG (manufactured by Nippon Emulsifier Co., Ltd.) 2.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 0.3% by mass
・ Orphine E1020 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
・ Self-dispersing polymer particles P-1: 8.0% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd.)… 0.2% by mass
・ Urea: 5.0% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd.): 1.5% by mass
・ Potassium nitrate: 0.05% by mass
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
・ CHEMGUARD S-760P (Chemguard, Inc., surfactant: 0.01% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Remaining amount when 100% by mass as a whole

<Composition of magenta ink>
-Pigment dispersion M: 42.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)): 1.0% by mass
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 0.2% by mass
・ 2-Pyrrolidone: 0.5% by mass
・ Glycerin: 3.0% by mass
・ Propylene glycol (made by ADEKA): 13.0% by mass
・ MFTG (manufactured by Nippon Emulsifier Co., Ltd.) 2.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 0.3% by mass
・ Orphine E1020 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
・ Self-dispersing polymer particles P-1: 8.0% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd.)… 0.2% by mass
・ Urea: 5.0% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd.): 1.5% by mass
・ Potassium nitrate: 0.05% by mass
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
・ CHEMGUARD S-760P (Chemguard, Inc., surfactant: 0.01% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Remaining amount when 100% by mass as a whole

<Composition of yellow ink>
Pigment dispersion Y: 35.0% by mass
Polymerizable compound a (specific example of compound represented by general formula (1)): 1.0% by mass
Polymerization initiator (Exemplary compound (X) -1; specific example of compound represented by general formula (X))
... 0.2% by mass
・ 2-Pyrrolidone: 0.5% by mass
・ Glycerin: 3.0% by mass
・ Propylene glycol (made by ADEKA): 10.0% by mass
・ MFTG (manufactured by Nippon Emulsifier Co., Ltd.) 2.0% by mass
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 0.3% by mass
・ Orphine E1020 (manufactured by Nissin Chemical Industry Co., Ltd., surfactant): 1.0% by mass
・ Self-dispersing polymer particles P-1: 8.0% by mass
・ PVP K-15 (manufactured by ISB Japan Co., Ltd.)… 0.2% by mass
・ Urea: 5.0% by mass
・ Cerosol 524 (manufactured by Chukyo Yushi Co., Ltd.): 1.5% by mass
・ Potassium nitrate: 0.05% by mass
・ Snowtex XS (Nissan Chemical Co., Ltd., colloidal silica): 0.3% by mass
・ Capstone FS-63 (manufactured by Dupont, surfactant): 0.01% by mass
-BYK-024 (Bic Chemie Japan Co., Ltd., antifoaming agent) ... 0.01% by mass
・ Ion-exchanged water: Remaining amount when 100% by mass as a whole

Example 6
In each ink composition of Example 5, ink compositions were prepared in the same manner except that the content of the polymerization initiator was increased from 0.2% by mass to 0.3% by mass. The ink composition was evaluated in the same manner as in Experiment No. 1 in Example 1.
As a result, it was confirmed that the effects of the present invention were observed in each ink composition.
Specifically, the evaluation result of each ink composition was that the ink stability at 60 ° C. with time was “A” and the abrasion resistance was “A” according to the above evaluation criteria.

Example 7
Each ink composition of Example 5 was prepared in exactly the same manner except that the content of the polymerization initiator was reduced from 0.2% by mass to 0.15% by mass. About the composition, evaluation similar to the experiment number 1 of Example 1 was performed.
As a result, it was confirmed that the effects of the present invention were observed in each ink composition.
Specifically, the evaluation result of each ink composition was that, according to the above evaluation criteria, the 60 ° C. temporal stability of the ink was “B” and the abrasion resistance was “B”.

DESCRIPTION OF SYMBOLS 12 ... Treatment liquid provision part 13 ... Treatment liquid drying zone 14 ... Ink discharge part 15 ... Ink drying zone 16 ... Ultraviolet irradiation part 16S ... Ultraviolet irradiation lamp 30K, 30C, 30M, 30Y ... Ink ejection head

Claims (12)

Ink-jet ink composition comprising water, a coloring material, a polymerization initiator represented by the following general formula (X), a polyfunctional (meth) acrylamide type polymerizable compound, and wax particles having a melting point of 40 ° C. or higher and 140 ° C. or lower. object.

[In General Formula (X), R ^X1 , R ^X2 , R ^X3 , and R ^X4 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an alkylthio group, a mercapto group, an acyl group, Or represents an amino group. n represents an integer of 1 or more and 4 or less. ] The inkjet ink composition according to claim 1, wherein the polyfunctional (meth) acrylamide type polymerizable compound is a (meth) acrylamide compound represented by the following general formula (1).

[In General Formula (1), R ¹ represents a hydrogen atom or a methyl group. R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms. However, R ² does not have a structure in which an oxygen atom and a nitrogen atom bonded to both ends of R ² are bonded to the same carbon atom of R ² . R ³ represents a divalent linking group. k represents 2 or 3. x, y, and z each independently represent an integer of 0 to 6, and x + y + z satisfies 0 to 18. ] Furthermore, the ink composition for inkjets of Claim 1 or Claim 2 containing the water-soluble solvent represented with the following general formula (B).

[In General Formula (B), W represents a divalent linking group that forms a heterocyclic ring together with the carbon atom and the nitrogen atom in General Formula (B). ]   The ink composition for inkjet according to any one of claims 1 to 3, wherein the wax constituting the wax particles is carnauba wax.   The inkjet ink composition according to claim 3, wherein the water-soluble solvent represented by the general formula (B) is 2-pyrrolidone.   The content of 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one is the content of the polymerization initiator represented by the general formula (X) The ink composition for inkjet according to any one of claims 1 to 5, which is 5.0 times or less of mass.   The contained mass of the wax particles is 0.2 to 10.0 times the contained mass of the polymerization initiator represented by the general formula (X). Ink-jet ink composition.   8. The content of the wax particles is 0.3 to 8.0 times the content of the polymerization initiator represented by the general formula (X). Ink-jet ink composition.   The content of the polymerization initiator represented by the general formula (X) is 0.1% by mass to 10.0% by mass with respect to the total amount of the inkjet ink composition. The ink composition for ink jet according to claim 1.   The content of the polymerization initiator represented by the general formula (X) is 0.1% by mass to 5.0% by mass with respect to the total amount of the inkjet ink composition. The ink composition for ink jet according to claim 1. The inkjet ink composition according to any one of claims 1 to 10, and
A treatment liquid comprising an aggregating component that forms an aggregate when contacted with the ink-jet ink composition;
An ink set. An ink set according to claim 11 is used,
A treatment liquid application step of applying the treatment liquid to a recording medium;
An ink application step of forming an image by applying the inkjet ink composition to a recording medium by an inkjet method;
An image forming method comprising: