JP2018159030A - Particle dispersion liquid, aqueous ink, ink cartridge, recording device, and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle dispersion liquid having excellent concentration re-dispersibility.SOLUTION: A particle dispersion liquid contains one or more compounds represented by formula (I) and (II) (R-Rindependently represent an alkyl group or an aryl group).SELECTED DRAWING: None

Description

  The present invention relates to a particle dispersion, an aqueous ink, an ink cartridge, a recording apparatus, and a recording method.

  A composition containing an infrared absorber is known as an ink or a toner that is fixed to a recording medium by light irradiation.

  For example, Patent Document 1 includes at least a coloring material, water, a water-soluble organic solvent, and a near-infrared absorber having a maximum absorption wavelength at 800 to 1200 nm, and the near-infrared absorber is adsorbed or encapsulated in resin particles, An aqueous inkjet recording ink dispersed in the state of near-infrared absorber-containing resin particles is disclosed.

  For example, Patent Document 2 contains an infrared absorbing material having an absorption maximum wavelength of 700 nm to 1500 nm and having an absorption coefficient in a wavelength region of 400 nm to less than 700 nm that is 10% or less of the absorption coefficient at the absorption maximum wavelength. An ink is disclosed.

  For example, Patent Document 3 discloses a water-based ink containing an aqueous dispersion of polymer particles of a water-insoluble vinyl polymer containing a hydrophobic dye, wherein the water-insoluble vinyl polymer is an alicyclic (meth) acrylate (a), A monomer composition containing a salt-forming group-containing monomer (b) and an alicyclic (meth) acrylate (a) and a monomer (c) copolymerizable with the salt-forming group-containing monomer (b) are polymerized. An aqueous ink that is a water-insoluble vinyl polymer is disclosed.

JP 2013-189596 A JP 2001-226618 A JP 2004-203996 A

  Conventionally, a particle dispersion in which particles containing an infrared absorber and a resin are dispersed in an aqueous medium has been used. When such a particle dispersion is used for, for example, an aqueous ink for an ink jet method (droplet discharge method), from the viewpoint of suppressing clogging at the discharge port (ink jet head), one of the aqueous media in the dispersion is used. Dispersibility (referred to as “concentrated redispersibility” in the present specification) when the part is once evaporated and concentrated (for example, the amount of the aqueous medium is concentrated to 40% by mass) and then diluted again by adding an aqueous medium. ) Is required. Further, even when the ink is used other than the water-based ink for the ink jet system, concentrated redispersibility is still required from the viewpoint of dispersion stability accompanying a change in ambient temperature environment.

  An object of the present invention is to provide an aqueous medium, particles containing at least one compound represented by the following general formula (I) and the following general formula (II), and a resin having an alkyl (meth) acrylate as a structural unit; In a mode in which the resin has a particle dispersion having an excellent concentrated redispersibility compared with a case where the resin has only an alicyclic hydrocarbon group having no bridging bond as an alicyclic hydrocarbon group in the molecular structure. Is to provide.

  Specific means for solving the problem includes the following modes.

The invention according to claim 1
An aqueous medium, and
An alkyl (meth) acrylate that contains at least one compound represented by the following general formula (I) and the following general formula (II) and contains an alicyclic hydrocarbon group having a bridging bond, is dispersed in the aqueous medium. Particles containing a resin having a unit and an acid value of 6 mgKOH / g or more and 100 mgKOH / g or less,
A particle dispersion containing

(In general formula (I), R ^1a , R ^1b , R ^1c and R ^1d each independently represents an alkyl group or an aryl group.
In general formula (II), R ^2a , R ^2b , R ^2c and R ^2d each independently represents an alkyl group. R ^2a and R ^2b and R ^2c and R ^2d may be independently connected to form a ring. )

The invention according to claim 2
2. The particle dispersion according to claim 1, wherein an average content of the alicyclic hydrocarbon group having a crosslinking bond in the molecular structure of the resin is 7% by mass or more and 50% by mass or less.

The invention according to claim 3
The particle dispersion according to claim 1, wherein the alicyclic hydrocarbon group having a bridging bond is a group having a bicyclo ring structure or a tricyclo ring structure.

The invention according to claim 4
An aqueous medium, and
An alkyl (meth) acrylate that contains at least one compound represented by the following general formula (I) and the following general formula (II) and contains an alicyclic hydrocarbon group having a bridging bond, is dispersed in the aqueous medium. Particles containing a resin having a unit and an acid value of 6 mgKOH / g or more and 100 mgKOH / g or less,
Water-based ink containing.

(In general formula (I), R ^1a , R ^1b , R ^1c and R ^1d each independently represents an alkyl group or an aryl group.
In general formula (II), R ^2a , R ^2b , R ^2c and R ^2d each independently represents an alkyl group. R ^2a and R ^2b and R ^2c and R ^2d may be independently connected to form a ring. )

The invention according to claim 5
An ink cartridge containing the water-based ink according to claim 4.

The invention according to claim 6
Ink applying means for containing the water-based ink according to claim 4 and applying the water-based ink to a recording medium;
Infrared irradiation means for irradiating the aqueous ink applied to the recording medium with infrared rays;
A recording apparatus comprising:

The invention according to claim 7 provides:
An ink application step of applying the water-based ink according to claim 4 to a recording medium;
An infrared irradiation step of irradiating the water-based ink applied to the recording medium with infrared rays;
A recording method.

According to the invention which concerns on Claim 1 or 3, it has an aqueous medium, at least 1 type of the compound represented by this general formula (I) and this general formula (II), and an alkyl (meth) acrylate as a structural unit. And a resin-containing particle, the concentrated redispersion is superior to when the resin has only an alicyclic hydrocarbon group that does not have a bridging bond as an alicyclic hydrocarbon group in the molecular structure. A particle dispersion having properties is provided.
According to the invention of claim 2, it has excellent concentration redispersibility compared with the case where the average content in the molecular structure of the resin of the alicyclic hydrocarbon group having a crosslink is less than 7% by mass. A particle dispersion is provided.

The invention according to claim 4 includes an aqueous medium, at least one compound represented by the general formula (I) and the general formula (II), and a resin having an alkyl (meth) acrylate as a structural unit. The resin has an excellent concentration redispersibility compared with a case where the resin has only an alicyclic hydrocarbon group having no bridging bond as an alicyclic hydrocarbon group in the molecular structure. An aqueous ink is provided.
According to the invention according to claim 5, 6 or 7, the structural unit comprises an aqueous medium, at least one of the compounds represented by the general formula (I) and the general formula (II), and an alkyl (meth) acrylate. And a water-based ink containing particles having a resin as a water-based ink, wherein the resin has only an alicyclic hydrocarbon group having no bridging bond as an alicyclic hydrocarbon group in the molecular structure. In comparison with the above case, an ink cartridge having excellent concentration and redispersibility, a recording apparatus using the water-based ink, or a recording method are provided.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment.

  Embodiments of the invention will be described below. These descriptions and examples illustrate embodiments and do not limit the scope of the invention.

In the present disclosure, when referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, the plurality of the substances present in the composition unless otherwise specified. It means the total amount of substance.
In the present disclosure, “alkyl” and “alkenyl” include not only chain hydrocarbons but also cyclic hydrocarbons.
In the present disclosure, “(meth) acrylate” and “(meth) acrylic acid” mean to include acrylate (acrylic acid) and methacrylate (methacrylic acid), and “(meth) acryloyl” means acryloyl and methacryloyl. It means to include.
In the present disclosure, the “aqueous medium” means water or a mixed solvent of water and other solvents and a mixed solvent containing water as a main solvent. In the present disclosure, the “main solvent” refers to a solvent having the largest mass among all the solvents constituting the mixed solvent.

<Particle dispersion>
The particle dispersion according to the present embodiment is a dispersion containing an aqueous medium and particles dispersed in the aqueous medium.
The particles include at least one compound represented by the following general formula (I) and the following general formula (II) (that is, a compound represented by the following general formula (I) and a compound represented by the following general formula (II). At least one of them, hereinafter also referred to as “specific compound”), and a resin.
This resin has an alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (hereinafter, also simply referred to as “bridged alicyclic group”) as a structural unit (having a bridged alicyclic group. And a resin having an acid value of 6 mgKOH / g or more and 100 mgKOH / g or less (hereinafter also simply referred to as “specific resin”).

(In general formula (I), R ^1a , R ^1b , R ^1c and R ^1d each independently represents an alkyl group or an aryl group.
In general formula (II), R ^2a , R ^2b , R ^2c and R ^2d each independently represents an alkyl group. R ^2a and R ^2b and R ^2c and R ^2d may be independently connected to form a ring. )

Conventionally, in order to make an aqueous medium contain a compound that is insoluble or hardly soluble in water, a particle dispersion technique in which the compound and resin-containing particles are formed and then dispersed in an aqueous medium. It has been known.
In addition, when using such a particle dispersion liquid for the water-based ink for inkjet systems (droplet discharge system), it is calculated | required that clogging at an ejection port (inkjet head) is suppressed. Therefore, in the particle dispersion, a part of the aqueous medium in the dispersion is temporarily evaporated (for example, 60% by weight of the aqueous medium is evaporated) and concentrated (for example, the amount of the aqueous medium is concentrated to 40% by weight), and then Dispersibility (concentrated redispersibility) when the aqueous medium is added and diluted again is required. In the case of a water-based ink having high concentration and re-dispersibility, even if it is concentrated by heating at the time of discharge by an ink jet method and particles remain as solids in the discharge port (inkjet head), Since it is well dispersed in the aqueous medium, clogging of the discharge port (inkjet head) can be suppressed. Further, even when the ink is used other than the water-based ink for the ink jet system, concentrated redispersibility is still required from the viewpoint of dispersion stability accompanying a change in ambient temperature environment.
In view of the above, the particle dispersion is required to improve the concentration redispersibility.

On the other hand, the particle dispersion liquid according to the present embodiment can provide excellent concentrated redispersibility by satisfying the above configuration.
The reason is presumed as follows.

First of all, in this embodiment, the particles have, as a structural unit, an alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (crosslinked alicyclic group) as a structural unit as a resin (crosslinked alicyclic ring). Specific resins (having structural units derived from alkyl (meth) acrylates containing groups). The crosslinked alicyclic group is a hydrocarbon group having a complicated three-dimensional structure and has a property of exhibiting high hydrophobicity, so that the particles are also considered to have high hydrophobicity.
Secondly, in this embodiment, the particles contain at least one compound represented by the general formula (I) and the general formula (II) as a compound. The specific compound containing a plurality of aromatic rings is considered to have high affinity with a specific resin having a bridged alicyclic group which is a hydrocarbon group having a complicated three-dimensional structure. As a result, the particles having a specific resin as a matrix resin exhibit excellent solubility (molecular dispersion state), exist in a finely dispersed state, that is, in a state in which aggregation is suppressed, and the specific resin is also high throughout the particle. It exists with uniformity. And since the nonuniformity of the specific resin in the particles is suppressed in this way, the hydrophobicity of the particles is considered to be exhibited with high uniformity over the entire particle surface.
As a result, when the particle dispersion contains an organic solvent in addition to the aqueous medium, a part of the aqueous medium in the dispersion is once evaporated and concentrated (for example, the amount of the aqueous medium is concentrated to 40% by mass). However, since the particles are hardly dissolved in the organic solvent and maintain the state of the particles, they are well dispersed when an aqueous medium is added thereafter. Further, even when the particle dispersion contains only an aqueous medium as a dispersion medium, the particles are maintained in an aqueous medium with few particles when concentrated, so that they are well dispersed when the aqueous medium is added thereafter.

  As described above, in this embodiment, excellent concentration redispersibility can be obtained.

Moreover, according to the particle dispersion according to the present embodiment, when the specific compound has infrared (IR) absorption performance, high infrared absorption performance (IR absorption performance) is exhibited.
As described above, this is because the affinity between a specific compound containing a plurality of aromatic rings and a specific resin having a bridged alicyclic group, which is a hydrocarbon group having a complicated three-dimensional structure, is high. This is because the particles are present in a finely dispersed state in the particles to be exhibited, and thus the specific compound is satisfactorily exhibited when it has IR absorption performance.

Moreover, according to this embodiment, when obtaining a particle dispersion liquid, production with a high yield can be performed.
This is because, as described above, the high hydrophobicity due to the specific resin having a bridged alicyclic group is exerted with high uniformity over the entire particle surface, and thereby high dispersibility is obtained in an aqueous medium. it is conceivable that. In addition, when the acid value of the specific resin is 6 mgKOH / g or more, the dispersion stability of the particles in the aqueous medium is enhanced, and when the acid value is 100 mgKOH / g or less, the water solubility is not too high. This is presumably because the formability of particles containing the specific resin and the specific compound is enhanced.

Furthermore, according to the particle dispersion according to the present embodiment, the particle size can be reduced.
As described above, the high hydrophobicity due to the specific resin having a crosslinked alicyclic group is exerted with high uniformity over the entire particle surface, thereby obtaining high dispersibility in an aqueous medium. It is thought that it is. Moreover, it is considered that the dispersion stability of the particles in the aqueous medium is enhanced when the acid value of the specific resin is 6 mgKOH / g or more.

  In the present embodiment, the dispersion state of the particles may be emulsification in which liquid particles are dispersed or suspension in which solid particles are dispersed. From the viewpoint of dispersion stability, suspension in which solid particles are dispersed is preferable. That is, the particle dispersion according to this embodiment may be an emulsion (emulsion) in which particles are dispersed in an aqueous medium in a liquid state, or may be a suspension (suspension) in which particles are dispersed in an aqueous medium. From the viewpoint of dispersion stability, a suspension is preferable.

  Hereinafter, the components, composition, manufacturing method and the like of the particle dispersion according to this embodiment will be described in detail.

[Specific compounds]
The particles contained in the particle dispersion according to the present embodiment include at least one compound represented by the following general formula (I) and the following general formula (II) (that is, a compound represented by the following general formula (I) and the following: Containing at least one of the compounds represented by formula (II).

  -Compound represented by general formula (I)-

(In general formula (I), R ^1a , R ^1b , R ^1c and R ^1d each independently represents an alkyl group or an aryl group.)

The alkyl group represented by R ^1a , R ^1b , R ^1c and R ^1d is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and 3 to 6 carbon atoms. The following alkyl groups are more preferable, and alkyl groups having 4 to 6 carbon atoms are more preferable.

The alkyl group represented by R ^1a , R ^1b , R ^1c and R ^1d may be a linear, branched or cyclic alkyl group, such as a methyl group, an ethyl group, n- Propyl group, isopropyl group, n-butyl group, isobutyl group (2-methylpropyl group), sec-butyl group (1-methylpropyl group), tert-butyl group (1,1-dimethylethyl group), n-pentyl Group, isopentyl group (3-methylbutyl group), neopentyl group (2,2-dimethylpropyl group), tert-pentyl group (1,1-dimethylpropyl group), n-hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, n-heptyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, n-octyl group, isooctyl group, sec- Octyl, 2-ethylhexyl, tert-octyl, n-nonyl, isononyl, sec-nonyl, tert-nonyl, n-decyl, isodecyl, sec-decyl, tert-decyl, n -Undecyl group, isoundecyl group, n-dodecyl group, isododecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, and bicyclo [2,2,2] octyl group.

Examples of the aryl group represented by R ^1a , R ^1b , R ^1c and R ^1d include a phenyl group and an alkyl-substituted phenyl group.
In the alkyl-substituted phenyl group, a phenyl group may be substituted with one alkyl group or a plurality of alkyl groups, but an alkyl-substituted phenyl group in which only one alkyl group is substituted is more preferable. preferable.
The alkyl group as the substituent is preferably an alkyl group having 1 to 10 carbon atoms, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group. Tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, n-heptyl group, isoheptyl group, sec- Heptyl, tert-heptyl, n-octyl, isooctyl, sec-octyl, tert-octyl, n-nonyl, isononyl, sec-nonyl, tert-nonyl, n-decyl, isodecyl Group, sec-decyl group, tert-decyl group and the like.

  Specific examples of the aryl group include phenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-propylphenyl group, 4-butylphenyl group (particularly 4-tert-butylphenyl group), and 3-methylphenyl group. And 2-methylphenyl group, and the like. Among them, a phenyl group is preferable.

The alkyl group and aryl group represented by R ^1a , R ^1b , R ^1c, and R ^1d may be substituted with a halogen atom (for example, fluorine or chlorine).

In the compound represented by the general formula (I), it is preferable that at least one of the groups represented by R ^1a , R ^1b , R ^1c and R ^1d is a branched alkyl group. More preferably, it is a compound represented by the formula (Ia).

(In General Formula (Ia), R ^11a represents a group represented by General Formula (1-R), and R ^11b , R ^11c, and R ^11d each independently represents an alkyl group.
In General Formula (1-R), R ^11e represents hydrogen or a methyl group, and e represents an integer of 0 or more and 3 or less. )

  The total carbon number of the group represented by the general formula (1-R) is preferably 6 or less, more preferably 5 or less, still more preferably 4 or less, and particularly preferably 4. The lower limit of the total carbon number is 3.

In General Formula (1-R), R ^e represents hydrogen or a methyl group. R ^e is preferably a methyl group. When R ^e is a methyl group, the group represented by the general formula (1-R) has a structure in which the terminal is branched into three, and the infrared absorption performance is further reduced as compared with the case where R ^e is hydrogen. Is suppressed.

  In general formula (1-R), e represents an integer of 0 or more and 3 or less. e is preferably an integer of 0 or more and 2 or less, more preferably 0 or 1, and still more preferably 0. The smaller the e is, the more the infrared absorption performance is suppressed.

  Specific examples of the group represented by the general formula (1-R) include isopropyl group, isobutyl group, tert-butyl group, 3-methylbutyl group (3-methylbutan-1-yl group), 2,2-dimethylpropyl. Group (2,2-dimethylpropan-1-yl group), 4-methylpentyl group (4-methylpentan-1-yl group), 3,3-dimethylbutyl group (3,3-dimethylbutan-1-yl) Group) and 4,4-dimethylpentyl group (4,4-dimethylpentan-1-yl group). Among these, an isopropyl group, an isobutyl group, and a tert-butyl group are more preferable, and a tert-butyl group is still more preferable.

In general formula (Ia), R ^11b , R ^11c and R ^11d each independently represents an alkyl group. It is preferable that at least one of R ^11b , R ^11c and R ^11d is a group represented by the general formula (1-R), and all of R ^11b , R ^11c and R ^11d are represented by the general formula (1-R). It is more preferred that As the number of groups represented by the general formula (1-R) in the general formula (Ia) increases, the decrease in infrared absorption performance is further suppressed.

When one of R ^11b , R ^11c and R ^11d is a group represented by the general formula (1-R), any of R ^11b , R ^11c and R ^11d is represented by the general formula (1-R). It may be a group. When two of R ^11b , R ^11c and R ^11d are groups represented by the general formula (1-R), any of R ^11b , R ^11c and R ^11d is represented by the general formula (1-R). It may be a group.
When two or more of R ^{a to} R ^d are a group represented by the general formula (1-R), a plurality of groups represented by the general formula (1-R) may have the same structure. It may be.

A preferred structure in the case where at least one of R ^11b , R ^11c and R ^11d is a group represented by the general formula (1-R) is as described above for R ^11a .

The alkyl group in the case where at least one of R ^11b , R ^11c, and R ^11d is other than the group represented by the general formula (1-R) may be any of linear, branched, and cyclic structures. Good. In this case, the alkyl group preferably has a larger number of branches, and the carbon chain is preferably shorter. As carbon number, 1 or more and 10 or less are preferable, 2 or more and 8 or less are more preferable, and 3 or more and 6 or less are still more preferable.
Specific examples of the alkyl group include a methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, sec-butyl group, 2-methylbutan-2-yl group, 3- Methylbutan-2-yl group, 3,3-dimethylbutan-2-yl group, 3-pentyl group, 2-methylpentan-3-yl group, 3-methylpentan-3-yl group, cyclopentyl group, cyclohexyl group and the like Is mentioned. Among these, a 2-methylbutan-2-yl group and a 3-methylpentan-3-yl group are preferable.

  Specific examples (compounds (Ia-1) to (Ia-10)) of the compounds represented by the general formula (I) are shown below.

  The compound represented by the general formula (I) is synthesized, for example, according to the following reaction scheme.

(1) Compounds in which R ^1a , R ^1b , R ^1c and R ^1d are all the same group

  First, the starting material 1 is allowed to act dropwise on an organic solvent (eg, tetrahydrofuran) solution of an organic magnesium halide (Grignard reagent, eg, ethylmagnesium chloride) under an inert atmosphere and cooling. Thereafter, in order to complete the reaction, the temperature may be returned to room temperature (for example, 20 ° C. to 25 ° C., the same applies hereinafter in this description) or higher. Subsequently, a formic acid derivative (for example, ethyl formate etc.) is dropped and allowed to act under cooling. Thereafter, the temperature may be returned to room temperature or higher in order to complete the reaction. An organic substance is extracted from the mixture after the reaction, and intermediate A is obtained from the separated organic layer.

  Next, the intermediate A and an oxidizing reagent (such as manganese oxide) are added to a solvent (such as cyclohexane), and the mixture is reacted by heating under reflux. Water generated during the reaction may be removed. Intermediate B is obtained from the organic layer of the reaction mixture. Purification may be performed when obtaining the intermediate B.

  Next, the cycloaddition reaction is performed on intermediate B. For example, sodium hydrogen monosulfide n hydrate is added to a solvent (for example, ethanol), and the intermediate B is added dropwise under cooling. Then, it is made to react at room temperature, After removing a solvent from a reaction liquid, salt is added until it is saturated, liquid separation is carried out, the organic phase is collect | recovered, and the intermediate body C is obtained from an organic phase. Purification may be performed when obtaining intermediate C.

  Next, a solvent (such as anhydrous tetrahydrofuran) and intermediate C are mixed in an inert atmosphere, and a Grignard reagent (such as methylmagnesium bromide) is added dropwise. After completion of the dropwise addition, the reaction solution is heated to reflux, and then ammonium bromide is added dropwise under cooling. The separated organic layer is dried and concentrated to give intermediate D.

  Next, in an inert atmosphere, intermediate D and squaric acid are dispersed in a solvent (such as a mixed solvent of cyclohexane and isobutanol), a basic compound (such as pyridine) is added, and the mixture is heated to reflux to obtain compound (I). -A is obtained. Water generated during the reaction may be removed. Further, purification, isolation, concentration and the like may be performed.

(2) Compounds in which R ^1a and R ^1d are the same group and R ^1b and R ^1c are the same group (R ^1a and R ^1b are different groups)
The process of obtaining the intermediate A in the reaction scheme (1) is changed to the following process.

  Under an inert atmosphere and under cooling, the starting material 1 is added dropwise to a solution of a Grignard reagent (for example, ethyl magnesium bromide) in an organic solvent (for example, tetrahydrofuran), and then the additional material 2 is added dropwise to react. A strong acid (such as hydrochloric acid) is added to the solution after the reaction under cooling, and then ether is added at room temperature to obtain an intermediate A ′ from the organic layer. Purification may be performed in obtaining intermediate A '.

(3) Compounds in which R ^1a and R ^1b are the same group and R ^1c and R ^1d are the same group (R ^1a and R ^1c are different groups)
As an intermediate D in the reaction scheme of (1), two types of compounds having different R ¹ structures are prepared, and these two types of compounds are reacted with squaric acid to obtain a compound represented by the general formula (I) Get.

A compound in which three of R ^{1a to} R ^1d are the same group, a compound in which two are the same group and the remaining two are different groups, and a compound in which all four groups are different can be synthesized according to the above reaction scheme.

  -Compound represented by general formula (II)-

(In general formula (II), R ^2a , R ^2b , R ^2c and R ^2d each independently represents an alkyl group. R ^2a and R ^2b and R ^2c and R ^2d are each independently linked to form a ring. May be.)

As the alkyl group represented by R ^2a , R ^2b , R ^2c and R ^2d , an alkyl group having 1 to 12 carbon atoms is preferable, and an alkyl group having 2 to 8 carbon atoms is more preferable.

The alkyl group represented by R ^2a , R ^2b , R ^2c and R ^2d may be a linear, branched or cyclic alkyl group, such as a methyl group, an ethyl group, n- Propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, isohexyl group, sec- Hexyl group, tert-hexyl group, n-heptyl group, isoheptyl group, sec-heptyl group, tert-heptyl group, n-octyl group, isooctyl group, sec-octyl group, tert-octyl group, n-nonyl group, isononyl Group, sec-nonyl group, tert-nonyl group, n-decyl group, isodecyl group, sec-decyl group, tert-dec Le group, n- undecyl group, isoundecyl group, n- dodecyl group, isododecyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, and bicyclo [2,2,2] octyl group and the like.

In addition, when R ^2a and R ^2b are connected to form a ring, or when R ^2c and R ^2d are connected to form a ring, the formed ring is a 5-membered ring, a 6-membered ring, or a 7-membered ring. A ring is preferable, and a 6-membered ring is more preferable.
Note that the ring formed may have a substituent, and examples of the substituent include an alkyl group.
The group at the portion connecting R ^2c and R ^2d is preferably an alkyl group having 3 to 6 carbon atoms.

  In the case of forming a ring by linking to each other, the formed ring structure includes cyclopentane, cyclohexane, cycloheptane, 3,5-dimethylcyclohexane, 3,5-diethylcyclohexane, 3,5-diisopropylcyclohexane, 3 , 3,5-trimethylcyclohexane, 3,3,5,5-tetramethylcyclohexane and the like.

An alkyl group represented by R ^2a , R ^2b , R ^2c and R ^2d (including a ring formed by connecting R ^2a and R ^2b and R ^2c and R ^2d ) is a halogen atom (for example, fluorine, chlorine ) May be substituted.

Specific examples of the compound represented by the general formula (II) (compounds (Ib-1) to (Ib-7)) are shown below, and in the general formula (II), R ^2a and R ^2b and Specific examples (compounds (Ic-1) to (Ic-7)) of compounds in which R ^2c and R ^2d are linked to form a ring are shown.

  The compound represented by the general formula (II) can be synthesized, for example, by a synthesis method described in JP 2010-077261 A, JP 2010-186014 A, JP 2011-039359 A, or the like.

The maximum absorption wavelength (λ _max ) in the tetrahydrofuran solution of the compound represented by the general formula (I) and the compound represented by the general formula (II) is preferably a wavelength of 760 nm to 1200 nm, and a wavelength of 780 nm to 1100 nm. It is more preferable that the wavelength is 800 nm or more and 1000 nm or less.

The molar extinction coefficient (ε _max ) at the maximum absorption wavelength (λ _max ) in the tetrahydrofuran solution of the compound represented by the general formula (I) and the compound represented by the general formula (II) is 1 × 10 ⁵ Lmol ^{−. 1} cm ⁻¹ or more and 6 × 10 ⁵ Lmol ⁻¹ cm ⁻¹ or less is preferable, 2 × 10 ⁵ Lmol ⁻¹ cm ⁻¹ or more and 6 × 10 ⁵ Lmol ⁻¹ cm ⁻¹ or less is more preferable, and 2.5 × 10 6 ⁵ Lmol ⁻¹ cm ⁻¹ or more and 6 × 10 ⁵ Lmol ⁻¹ cm ⁻¹ or less is more preferable.

-Other compound which has infrared absorptivity Particle | grains may contain the compound which has other infrared absorptivity other than the compound represented by this general formula (I), and this general formula (II). However, the content of the other compounds having infrared absorptivity is, from the viewpoint of infrared absorption performance, all the compounds having infrared absorptivity contained in the particles (compounds represented by general formula (I) and general formula ( Including the compound represented by II), the content is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably not.
Other compounds having infrared absorptivity include conventionally known compounds having infrared absorptivity, such as cyanine compounds and aminium compounds.

[Specific resin]
The particles contained in the particle dispersion according to the present embodiment have an alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (crosslinked alicyclic group) as a structural unit, and an acid value of 6 mgKOH. A resin (specific resin) that is not less than / g and not more than 100 mgKOH / g is contained.

  The specific resin can be obtained by polymerizing an alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (bridged alicyclic group) as at least one monomer.

-Alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond As an alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (bridging alicyclic group), for example, the following general Examples thereof include compounds represented by formula (A1) or general formula (A2).
Formula (A1) H ₂ C═CH—C (═O) —O— (R ^A1 ) _n —R ^A2
Formula _{(A2) H 2 C = C} (-CH 3) -C (= O) -O- (R A1) n -R A2
(In General Formula (A1) and General Formula (A2), R ^A1 represents an alkyl group, R ^A2 represents an alicyclic hydrocarbon group having a bridging bond (bridged alicyclic group), and n is 0 or 1 is represented.)

  Here, the alicyclic hydrocarbon group having a bridging bond (bridged alicyclic group) means two non-adjacent carbons constituting a ring in a four-membered or higher alicyclic structure (cycloaliphatic structure). A group having a structure in which atoms (or heteroatoms) are connected by a single bond or a bond via an organic group.

  As the ring structure in the alicyclic hydrocarbon group having a bridge bond (bridged alicyclic group), a bicyclic structure (bicyclo ring structure), a tricyclic structure (tricyclo ring structure), a polycyclic ring or more Examples thereof include a cyclic structure. Among them, a bicyclic structure (bicyclo ring structure) or a tricyclic structure (tricyclo ring structure) is preferable.

  The bridged alicyclic group may be an unsubstituted group or a substituted group. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, a hydroxyl group, a primary amino group, a secondary amino group, a tertiary amino group, an alkylcarbonyl group, an arylcarbonyl group, and a cyano group. Etc.

  The number of carbon atoms in the bridged alicyclic group (including the substituent when it has a substituent) is preferably 8 or more and 20 or less from the viewpoint of viscosity and solubility.

Examples of the alicyclic hydrocarbon group having a bridging bond (crosslinked alicyclic group) include the following groups.
(1) Bicyclohexyl group (bicyclo [2.1.1] hexyl group)
(2) Norbornyl group (bicyclo [2.2.1] heptyl group)
(3) Isobornyl group (1,7,7-trimethyl-bicyclo [2.2.1] heptyl group)
(4) Dicyclopentanyl group (tricyclo [5.2.1.0 (2,6)] decanyl group)
(5) Dicyclopentenyl group (tricyclo [5.2.1.0 (2,6)] dec-3-enyl group)
(6) adamantyl group (tricyclo [3.3.1.1 (3,7)] decanyl group)
(7) Bicyclo [4.3.0] nonyl group

Specific examples of the alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (crosslinked alicyclic group) include the following compounds.
(1m) Isobornyl methacrylate
(2m) Dicyclopentanyl methacrylate
(3m) 2-Methyl-2-adamantyl methacrylate
(4m) 2-ethyl-2-adamantyl methacrylate
(5m) 3-Hydroxy-1-adamantyl methacrylate
(6m) Dicyclopentenyl methacrylate
(7m) Dicyclopentenyloxyethyl methacrylate
(1a) Isobornyl acrylate
(2a) Dicyclopentanyl acrylate
(3a) 2-Methyl-2-adamantyl acrylate
(4a) 2-ethyl-2-adamantyl acrylate
(5a) 3-Hydroxy-1-adamantyl acrylate
(6a) Dicyclopentenyl acrylate
(7a) Dicyclopentenyloxyethyl acrylate

  The proportion of the alkyl (meth) acrylate containing the bridged alicyclic group in the total monomer as the raw material of the specific resin is that of the alicyclic hydrocarbon group having a bridge bond (bridged alicyclic group). It is preferable to adjust so that the content falls within the following range.

The average content of the alicyclic hydrocarbon group having a bridging bond (crosslinked alicyclic group) in the molecular structure of the specific resin is preferably 7% by mass or more and 50% by mass or less, and 12% by mass. The content is more preferably 40% by mass or less, and further preferably 12% by mass or more and 35% by mass or less.
When the average content of the bridged alicyclic group is 7% by mass or more, the concentration redispersibility is easily improved, and the infrared absorption performance is easily improved. On the other hand, when the average content of the bridged alicyclic group is 50% by mass or less, it is preferable in that the resin dispersion can be easily produced while suppressing the decrease in the solubility of the resin in the organic solvent.
The average content of the bridged alicyclic group is measured by the following method.
When the particle dispersion or aqueous ink contains a pigment, the pigment dispersion is removed by centrifugation or filtration and neutralized with hydrochloric acid until acidic. The resulting solid is recovered, washed with water, methanol, etc. and dried to recover the resin. Determination of resin monomer structure and copolymerization ratio by pyrolysis GC-MS (Gas Chromatography-Mass spectrometry) and proton NMR (nuclear magnetic resonance), content of crosslinked alicyclic group / resin Calculate by mass.
For example, in the case of isobornyl methacrylate / methyl methacrylate / acrylic acid copolymer (mass ratio of each monomer: 45/47/8), the mass of isobornyl group accounts for 61.7% of isobornyl methacrylate. × 0.617 / 100 = 27.8

-Monomer which has group which provides acid value Moreover, it is preferable that specific resin has a structural unit which provides an acid value. That is, a specific resin polymerizes a monomer having a group that imparts an acid value as a kind of monomer in addition to an alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (crosslinked alicyclic group). It is preferable that it is resin obtained by this.
Examples of the monomer having a group that imparts an acid value include a carboxy group-containing monomer, a sulfo group-containing monomer, and a phosphate group-containing monomer.

  Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, crotonic acid, itaconic acid monoalkyl esters (for example, itaconic acid monomethyl, itaconic acid monoethyl, itaconic acid monobutyl, etc. ), Maleic acid monoalkyl esters (for example, monomethyl maleate, monoethyl maleate, monobutyl maleate, etc.), 2-carboxyethyl (meth) acrylate, styrene carboxylic acid and the like. As the carboxy group-containing monomer, acrylic acid, methacrylic acid, and 2-carboxyethyl acrylate are preferable, and 2-carboxyethyl acrylate is particularly preferable.

  Examples of the sulfo group-containing monomer include (meth) acryloyloxyalkylsulfonic acid (for example, (meth) acryloyloxymethanesulfonic acid, (meth) acryloyloxyethanesulfonic acid, (meth) acryloyloxypropanesulfonic acid, etc.), acrylamide Alkylsulfonic acid (for example, 2-acrylamido-2-methylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylbutanesulfonic acid, etc.), methacrylamide alkylsulfonic acid (for example, 2 -Methacrylamido-2-methylethanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylbutanesulfonic acid, etc.), styrenesulfonic acid, vinylbenzylsulfonic acid And the like. As the sulfo group-containing monomer, styrene sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid are preferable.

  Examples of the phosphoric acid group-containing monomer include mono 2- (meth) acryloyloxyethyl phosphate, monovinyl phosphate, and the like.

One type of monomer having a group that imparts an acid value may be used, or two or more types may be used in combination.
In addition, it is preferable to adjust the ratio for which the monomer which has group which provides this acid value occupies in all the monomers used as the raw material of specific resin so that an acid value may become the range mentioned later.

Other monomers In addition to specific structural units, the specific resin includes, as structural units, alkyl (meth) acrylates containing alicyclic hydrocarbon groups having a bridging bond (crosslinked alicyclic groups), and structural units that impart acid values. Other structural units may be included. That is, when the specific resin is formed by polymerizing a monomer having a group that imparts an acid value in addition to an alkyl (meth) acrylate containing an alicyclic hydrocarbon group having a bridging bond (crosslinked alicyclic group) May be a resin obtained by polymerizing another monomer as a kind of monomer in addition to the monomer having a group imparting acid value).

  The other monomer is not particularly limited as long as it is a monomer copolymerizable with the alkyl (meth) acrylate containing the bridged alicyclic group.

Examples of other monomers include the following monomers. Examples of alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n- Examples include butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, and the like. It is done.

  Examples of (meth) acrylates other than alkyl groups or substituted alkyl groups include, for example, furfuryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-methoxyethyl (meth) acrylate, glycidyl (meth) acrylate, 2,2,2 -Tetrafluoroethyl (meth) acrylate, phenyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, 3-phenoxy-2-hydroxy-propyl (meth) acrylate, 2- Methoxyethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, ethoxytriethylene glycol (meth) acrylate, (Poly) ethyleneoxy group or polypropyleneoxy group such as toxipolyethylene glycol (eg having a weight average molecular weight of 200 to 1000) mono (meth) acrylate, polyethylene glycol (eg having a weight average molecular weight of 200 to 1000) mono (meth) acrylate An ethylenically unsaturated monomer containing 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate, Examples include 2,2-dimethyl-3-hydroxypropyl (meth) acrylate.

  Examples of styrenes include styrene, substituted styrene (α-methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, and vinylbenzoic acid. Methyl ester, etc.), and styrene macromers having a polystyrene structural unit.

  Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl chloroacetate, vinyl methoxy acetate, vinyl phenyl acetate, vinyl benzoate, vinyl salicylate, and the like. It is done.

  Examples of acrylamides include acrylamide, methyl acrylamide, ethyl acrylamide, propyl acrylamide, butyl acrylamide, tert-butyl acrylamide, tert-octyl acrylamide, cyclohexyl acrylamide, benzyl acrylamide, hydroxymethyl acrylamide, methoxymethyl acrylamide, butoxymethyl acrylamide, and methoxyethyl. Examples include acrylamide, phenylacrylamide, dimethylacrylamide, diethylacrylamide, β-cyanoethylacrylamide, N- (2-acetoacetoxyethyl) acrylamide, diacetoneacrylamide, and the like.

  Examples of methacrylamides include methacrylamide, methyl methacrylamide, ethyl methacrylamide, propyl methacrylamide, butyl methacrylamide, tert-butyl methacrylamide, cyclohexyl methacrylamide, benzyl methacrylamide, hydroxymethyl methacrylamide, methoxyethyl methacrylamide, Examples include phenylmethacrylamide, dimethylmethacrylamide, β-cyanoethylmethacrylamide, N- (2-acetoacetoxyethyl) methacrylamide and the like.

  Examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, and 2,3-dimethylbutadiene.

  Examples of vinyl ethers include methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether, and the like.

  Other monomers include, for example, butyl crotonate, hexyl crotonate, dimethyl itaconate, dibutyl itaconate, diethyl maleate, dimethyl maleate, dibutyl maleate, diethyl fumarate, dimethyl fumarate, dibutyl fumarate, methyl vinyl ketone , Phenyl vinyl ketone, methoxyethyl vinyl ketone, N-vinyl oxazolidone, N-vinyl pyrrolidone, vinylidene chloride, methylene malon nitrile and the like.

Specific Examples The specific compounds P01 to P20 and P41 to P47 are listed below as specific examples of the specific resin. However, the specific resin is not limited to these in the present embodiment. An example of the mass ratio of the copolymer component is shown in parentheses.

P01: Isobornyl methacrylate / methyl methacrylate / acrylic acid-2-carboxyethyl copolymer (45/49/6)
P02: Isobornyl methacrylate / phenoxyethyl methacrylate / methacrylic acid / acrylic acid-2-carboxyethyl copolymer (30/50/14/6)
P03: Isobornyl methacrylate / ethyl methacrylate / styrene carboxylic acid / acrylic acid-2-carboxyethyl copolymer (50/40/2/8)
P04: Isobornyl methacrylate / isobutyl methacrylate / 2-acrylamido-2-methylpropanesulfonic acid / 2-carboxyethyl acrylate copolymer (50/45/2/3)
P05: Isobornyl methacrylate / styrene / phenoxyethyl methacrylate / methyl methacrylate / acrylic acid-2-carboxyethyl copolymer (30/30/20/15/5)
P06: Isobornyl methacrylate / ethyl acrylate / acrylic acid-2-carboxyethyl copolymer (80/14/6)
P07: Isobornyl methacrylate / butyl acrylate / ethyl methacrylate / acrylic acid-2-carboxyethyl copolymer (30/15/45/10)
P08: Isobornyl methacrylate / styrene / methyl methacrylate / tetrahydrofurfuryl methacrylate / -2-carboxyethyl acrylate copolymer (30/20/25/20/5)
P09: Isobornyl methacrylate / dicyclopentenyloxyethyl methacrylate / methyl methacrylate / -2-carboxyethyl acrylate copolymer (30/20/45/5)
P10: Isobornyl methacrylate / 4-tert-butylstyrene / isobutyl methacrylate / acrylic acid-2-carboxyethyl copolymer (50/10/30/10)

P11: Dicyclopentanyl methacrylate / styrene / methyl methacrylate / acrylic acid-2-carboxyethyl copolymer (30/20/44/6)
P12: Dicyclopentanyl methacrylate / ethyl methacrylate / acrylic acid-2-carboxyethyl copolymer (50/45/5)
P13: Dicyclopentanyl methacrylate / methyl methacrylate / methacrylic acid / acrylic acid-2-carboxyethyl copolymer (45/48/3/4)
P14: Dicyclopentanyl methacrylate / isobornyl methacrylate / methyl methacrylate / mono 2- (meth) acryloylethyl phosphate / -2-carboxyethyl acrylate copolymer (32/20/40/4/4)
P15: Dicyclopentenyl acrylate / ethyl acrylate / acrylic acid-2-carboxyethyl copolymer (50/40/10)
P16: Dicyclopentenyl acrylate / methyl methacrylate / ethoxytriethylene glycol methacrylate / acrylic acid-2-carboxyethyl copolymer (60/15/15/10)
P17: Dicyclopentenyl acrylate / styrene / methyl methacrylate / acrylic acid-2-carboxyethyl copolymer (40/15/39/6)
P18: Dicyclopentenyloxyethyl acrylate / methyl methacrylate / hexyl acrylate / acrylic acid-2-carboxyethyl copolymer (40/40/5/15)
P19: Dicyclopentenyloxyethyl acrylate / ethyl methacrylate / styrene / acrylic acid-2-carboxyethyl copolymer (30/45/15/10)
P20: Dicyclopentanyl acrylate / isobornyl methacrylate / methyl methacrylate / -2-carboxyethyl acrylate copolymer (40/10/40/10)

P40: Isobornyl methacrylate / methyl methacrylate / acrylic acid copolymer (45/47/8)
P41: Isobornyl methacrylate / styrene / methyl methacrylate / methacrylic acid copolymer (30/20/42/8)
P42: Isobornyl methacrylate / ethyl methacrylate / styrene carboxylic acid copolymer (50/47/3)
P43: Isobornyl methacrylate / methyl methacrylate / 2-acrylamido-2-methylpropanesulfonic acid copolymer (42/54/4)
P44: Dicyclopentanyl methacrylate / styrene / methyl methacrylate / 2-acrylamido-2-methylpropanesulfonic acid copolymer (30/20/46/4)
P45: Dicyclopentanyl methacrylate / phenoxyethyl methacrylate / isobutyl methacrylate / styrene carboxylic acid copolymer (30/35/25/10)
P46: Dicyclopentanyl methacrylate / ethyl methacrylate / mono 2-methacryloyloxyethyl phosphate copolymer (30/60/10)
P47: Dicyclopentenyl acrylate / ethyl methacrylate / sodium styrenesulfonate copolymer (50/47/3)

-Physical property of specific resin The acid value of specific resin is 6 mgKOH / g or more and 100 mgKOH / g or less. When the acid value is 6 mgKOH / g or more, the dispersibility of the specific resin in the aqueous medium is not relatively lowered, and the dispersion stability of the particles is improved. On the other hand, when the acid value is 100 mgKOH / g or less, the water solubility of the specific resin is not relatively high, and the specific resin and the compound represented by the general formula (I) and the general formula (II) are represented. The formation of particles containing a specific compound (specific compound) is enhanced, and particles that are stably dispersed in an aqueous medium are obtained.
From these viewpoints, the acid value of the specific resin is preferably 7 mgKOH / g or more and 80 mgKOH / g or less, and more preferably 8 mgKOH / g or more and 60 mgKOH / g or less.

  In this embodiment, the acid value of the specific resin is a value determined by a neutralization titration method defined in JIS K0070: 1992.

The molecular weight range of the specific resin is preferably 3000 or more and 200,000 or less, more preferably 5000 or more and 150,000 or less, and further preferably 10,000 or more and 100,000 or less as a weight average molecular weight. When the weight average molecular weight is 3000 or more, the content ratio of the water-soluble component described later is reduced, and the specific compound (the compound represented by the general formula (I) and the compound represented by the general formula (II)) is dispersed. Suitable for. On the other hand, when the weight average molecular weight is 200,000 or less, it is excellent in solubility in an organic solvent and the viscosity of the polymer solution dissolved in the organic solvent can be suppressed. Therefore, the dispersion stability of the particles is excellent.
The weight average molecular weight of the resin is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

  The glass transition temperature of the specific resin is preferably 40 ° C. or higher and 150 ° C. or lower. When the glass transition temperature is 40 ° C. or higher, the image formed using the ink containing the specific resin is excellent in scratch resistance and blocking resistance. When the glass transition temperature is 150 ° C. or lower, the ink containing the specific resin is used. Excellent in abrasion resistance of the image formed by using. In this respect, the glass transition temperature of the specific resin is more preferably 60 ° C. or higher and 140 ° C. or lower, and further preferably 70 ° C. or higher and 130 ° C. or lower.

When the specific resin is used as a resin dispersion, the ratio of the water-soluble component to the solid content contained in the dispersion is preferably 10% by mass or less.
Usually, the individual molecules constituting the resin aggregate have variations in the composition of the structural units, and therefore, the individual molecules have variations in water solubility. Resin molecules having a relatively high solubility in water correspond to the “water-soluble component” referred to herein. A water-soluble component, that is, a resin molecule having a relatively high solubility in water, has a relatively low dispersibility of the specific compound (the compound represented by the general formula (I) and the compound represented by the general formula (II)). It is easy to become. Therefore, when the specific resin is used as a resin dispersion, the less water-soluble components contained in the dispersion, the better. Further, from the viewpoint of suppressing the swelling of particles containing a specific resin and adhesion between particles, and maintaining stable dispersion, the specific resin is a water-soluble component contained in the dispersion when used as a resin dispersion. The smaller the number, the better. From these viewpoints, when the specific resin is used as a dispersion, the ratio of the water-soluble component to the solid content in the dispersion is preferably 10% by mass or less, more preferably 8% by mass or less, and 5% by mass or less. Is more preferable, and the smaller is more preferable.

The ratio of the water-soluble component is measured by the following method.
A resin dispersion in which resin is dispersed in water (solid content concentration 10% by mass, liquid temperature 23 ± 0.5 ° C.) is prepared. At that time, a neutralizing agent is used as necessary for dispersing the resin. The resin dispersion is centrifuged into a dispersoid and a medium using a centrifugal ultrafiltration filter unit, the separated medium is dried, the mass of the dried solid is measured, and the solid content of the resin dispersion (= The ratio of the amount of dry solids of the medium to the amount of resin used in the preparation of the resin dispersion + the weight of the neutralizing agent used in the process of preparing the resin dispersion) is calculated and used as the ratio (mass%) of the water-soluble component.

-Other resin In this embodiment, you may use together resin other than specific resin as resin contained in particle | grains. Examples of the resin other than the specific resin include known resins such as polyester, polyurethane, polyamide, polyurea, and polycarbonate.
However, the specific resin is preferably the main resin among all the resins contained in the particles, and the specific resin is preferably the resin having the largest mass among all the resins. Specifically, the mass ratio of the specific resin in the total resin is preferably more than 50% by mass, more preferably 80% by mass or more, further preferably 90% by mass or more, and 100% by mass. It is particularly preferred that

[Aqueous medium]
The medium of the particle dispersion is water or a mixed solvent containing water as a main solvent. The mixed solvent is, for example, a mixture of water and a water-soluble organic solvent.

  The water is preferably purified water such as distilled water, ion-exchanged water, or ultrafiltered water from the viewpoint of suppressing contamination with impurities or generation of microorganisms.

  Examples of the water-soluble organic solvent include alcohols, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, and sulfur-containing solvents. The water-soluble organic solvent contained in the particle dispersion is, for example, a residue of the organic solvent used for dissolving the compound represented by the general formula (1) or the specific polyester in the production process of the particle dispersion.

The content of water is preferably 50% by mass or more and 95% by mass or less, and more preferably 60% by mass or more and 90% by mass or less with respect to the total mass of the particle dispersion.
The content of the water-soluble organic solvent is preferably 30% by mass or less and more preferably 10% by mass or less with respect to the total mass of the particle dispersion.

[Other ingredients]
The particle dispersion according to the present embodiment is a compound other than the specific compound (the compound represented by the general formula (I) and the compound represented by the general formula (II)) (for example, squarylium dye, croconium dye, Phthalocyanine dyes, cyanine dyes, aminium dyes, etc.), UV-absorbing compounds (for example, benzotriazole compounds, benzophenone compounds, etc.), colorants, neutralizers, surfactants, dispersion stabilizers, specific A polymer other than polyester may be included.

[Production method of particle dispersion]
Examples of the method for producing the particle dispersion include a phase inversion emulsification method and an impregnation method in which a specific resin particle is impregnated with a compound having infrared absorbing ability, and the phase inversion emulsification method is preferable.

  The phase inversion emulsification method is a compound having an infrared absorbing ability in an organic solvent (including a compound represented by the general formula (I) and at least one compound (specific compound) represented by the general formula (II)), And a solution in which the specific resin is dissolved, neutralizing the specific resin by adding a neutralizing agent to the solution, and then gradually mixing water to contain both the compound having infrared absorption ability and the specific resin. This is a method of forming particles into a dispersed state. The dispersion state here may be emulsification in which liquid particles are dispersed or suspension in which solid particles are dispersed. From the viewpoint of dispersion stability, a suspension in which solid particles are dispersed is preferable. The organic solvent is preferably removed from the viewpoint of dispersion stability of the particles when the solubility of the organic solvent in water is 10% by mass or less, or when the vapor pressure of the organic solvent is higher than water. . Neutralization is not an essential step, but when the specific resin has an unneutralized dissociable group, it is preferably performed from the viewpoint of pH adjustment of the dispersion.

  In the impregnation method, a particle dispersion of a specific resin is prepared, and the particle dispersion and a compound having an infrared absorbing ability in an organic solvent (the compound represented by the general formula (I) and the general formula (II)). After mixing with a solution in which at least one kind of compound (including a specific compound) is dissolved, the organic resin is gradually removed to impregnate a specific resin particle with a compound having infrared absorbing ability to form a particle. is there. The particles of the specific resin may be liquid particles or solid particles, and solid particles are preferable from the viewpoint of dispersion stability. The specific resin particle dispersion is prepared, for example, by preparing a solution in which the specific resin is dissolved, neutralizing the solution by adding a neutralizing agent, and then removing the organic solvent while gradually mixing water. .

Organic solvent The organic solvent used for the phase inversion emulsification method and impregnation method includes a compound having infrared absorbing ability (the compound represented by the general formula (I) and the general formula (II) (a specific compound). ) And the solubility of the specific resin. Specifically, for example, ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone; alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol; chloroform, methylene chloride, and the like Chlorine solvents; aromatic solvents such as benzene and toluene; ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate; ether solvents such as diethyl ether, tetrahydrofuran and dioxane; ethylene glycol monomethyl ether and ethylene glycol dimethyl ether Glycol ether solvents; and the like. These organic solvents may be used alone or in combination of two or more.

  As the usage-amount of an organic solvent, 10 mass parts or more and 2000 mass parts or less are preferable with respect to 100 mass parts of specific resin, and 100 mass parts or more and 1000 mass parts or less are more preferable. When the amount of the organic solvent used is 10 parts by mass or more with respect to 100 parts by mass of the specific resin, the dispersion of the particles is stable, and when the amount of the organic solvent used is 2000 parts by mass or less with respect to 100 parts by mass of the specific resin, The process of removing the solvent is unnecessary or takes a short time.

-Neutralizing agent As a neutralizing agent used for the phase inversion emulsification method and the impregnation method, when a specific resin has an anionic group, an organic base and an inorganic alkali are mentioned. Examples of the organic base include triethanolamine, diethanolamine, N-methyldiethanolamine, dimethylethanolamine and the like. Examples of the inorganic alkali include alkali metal hydroxides (for example, sodium hydroxide, lithium hydroxide, potassium hydroxide, etc.), carbonates (for example, sodium carbonate, sodium hydrogencarbonate, etc.), ammonia and the like.
The addition amount of the neutralizing agent is preferably such that the pH of the particle dispersion is in the range described later, from the viewpoint of dispersion stability of the particles.

  The amount of the specific resin used in the phase inversion emulsification method and the impregnation method, and the content of the specific resin contained in the particle dispersion are the compounds having infrared absorbing ability (in the general formula (I) and the general formula (II)). 100 parts by mass or more and 9900 parts by mass or less are preferable, and 300 parts by mass or more and 4900 parts by mass or less are more preferable with respect to 100 parts by mass of at least one kind of compound (including a specific compound). When the amount of the specific resin used (content of the specific resin) is 100 parts by mass or more with respect to 100 parts by mass of the compound having infrared absorbing ability, the dispersion of the compound having infrared absorbing ability becomes stable, and the amount of the specific resin used ( When the content of the specific resin is 9900 parts by mass or less with respect to 100 parts by mass of the compound having infrared absorbing ability, the infrared absorbing efficiency of the infrared absorbing particle dispersion is good.

  In the phase inversion emulsification method and the impregnation method, the compound represented by the general formula (I), the compound represented by the general formula (II), and an organic compound other than the specific resin are also used, and the compound is represented by the general formula The compound represented by (I) and the compound represented by the general formula (II) and the specific resin may be granulated to form particles containing the three. Examples of the organic compound that forms particles together include, for example, dyes, compounds represented by the general formula (I), and compounds having infrared absorbing ability other than the compounds represented by the general formula (II) (for example, squarylium dyes). , Croconium-based dyes, naphthalocyanine-based dyes, cyanine-based dyes, aminium-based dyes, etc.), and compounds having ultraviolet absorbing ability (for example, benzotriazole-based compounds, benzophenone-based compounds, etc.).

[Physical properties of particle dispersion]
The volume average particle size of the particles contained in the particle dispersion is preferably 10 nm to 150 nm, more preferably 10 nm to 120 nm, and still more preferably 10 nm to 100 nm. When the volume average particle diameter is 10 nm or more, the light resistance is excellent, and when the volume average particle diameter is 150 nm or less, the droplet ejection characteristics of the ink jet system are excellent. The particle size distribution may be either a wide particle size distribution or a monodisperse particle size distribution.
The volume average particle size and particle size distribution of the particles are measured using a light scattering method.

The pH of the particle dispersion according to this embodiment suppresses decomposition of the compounds represented by the general formula (I) and the general formula (II), for example, from the viewpoint of suppressing a decrease in infrared absorption performance over time. 10.5 or less is preferable, 10.0 or less is more preferable, 9.5 or less is further more preferable, and 9.0 or less is still more preferable. On the other hand, from the viewpoint of stably dispersing the specific resin and particles, the pH of the particle dispersion according to this embodiment is preferably 6.0 or more, more preferably 6.5 or more, and even more preferably 7.0 or more. .
In addition, since a general aqueous ink is alkaline (pH of about 8 to 10), the pH of the particle dispersion according to this embodiment is also from the viewpoint of preparing an aqueous ink using the particle dispersion according to this embodiment. The above range is preferred.
In this embodiment, the pH of the particle dispersion is measured under an environment of a temperature of 23 ± 0.5 ° C. and a relative humidity of 55 ± 5%.

  The surface tension of the particle dispersion according to this embodiment is preferably 20 mN / m or more and 40 mN / m or less, and more preferably 25 mN / m or more and 35 mN / m or less. In this embodiment, the surface tension of the particle dispersion is measured using a Wilhelmy surface tension meter in an environment of a temperature of 23 ± 0.5 ° C. and a relative humidity of 55 ± 5%.

The viscosity of the particle dispersion according to this embodiment is preferably 1 mPa · s to 30 mPa · s, and more preferably 2 mPa · s to 20 mPa · s. In this embodiment, the viscosity of the particle dispersion is measured under the conditions of a temperature of 23 ± 0.5 ° C. and a shear rate of 1400 s ⁻¹ using a TV-20 viscometer (Toki Sangyo) as a measuring device.

<Water-based ink>
The aqueous ink according to the present embodiment is an aqueous ink containing an aqueous medium and particles dispersed in the aqueous medium, and the particles are compounds represented by the general formula (I) and the general formula (II), In addition, it contains a specific resin.

  The details of the compound represented by the general formula (I) and the general formula (II), the specific resin, and the infrared-absorbing particles in the water-based ink according to the present embodiment are described for the particle dispersion according to the present embodiment. That's right.

  The water-based ink according to this embodiment includes, for example, the particle dispersion itself according to this embodiment; a composition obtained by adding at least a colorant to the particle dispersion according to this embodiment; A composition to which such a particle dispersion is added.

[Aqueous medium]
The aqueous ink medium is water or a mixed solvent containing water as a main solvent. The mixed solvent is, for example, a mixture of water and a water-soluble organic solvent. Examples of the water-soluble organic solvent include alcohols, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, and sulfur-containing solvents. The details of water and the water-soluble organic solvent in the water-based ink are the same as those described for the particle dispersion.

The content of water is preferably 40% by mass or more and 80% by mass or less, and more preferably 50% by mass or more and 80% by mass or less with respect to the total mass of the water-based ink.
The content of the water-soluble organic solvent is preferably 50% by mass or less and more preferably 40% by mass or less with respect to the total mass of the water-based ink.

[Colorant]
Examples of the colorant include pigments and dyes, and pigments are preferable from the viewpoint of light resistance of an image.

  When a pigment is used as the colorant, it is preferable to use a pigment dispersant together. Examples of the pigment dispersant include all known polymer dispersants and surfactants. One type of pigment dispersant may be used, or two or more types may be used in combination. Although the content of the pigment dispersant varies depending on the type of pigment and the type of pigment dispersant, it cannot be generally stated, but it is preferably 0.1% by mass to 100% by mass with respect to the pigment content.

  Examples of the pigment include a pigment that self-disperses in water (hereinafter referred to as “self-dispersing pigment”). The self-dispersing pigment refers to a pigment having a hydrophilic group on the pigment surface and being dispersed in water without the presence of a pigment dispersant. Examples of the self-dispersing pigment include all known self-dispersing pigments obtained by subjecting the pigment to surface modification treatment such as coupling agent treatment, polymer graft treatment, plasma treatment, oxidation treatment, and reduction treatment. Pigments.

  Examples of the pigment include so-called microcapsule pigments coated with a resin. Commercially available microcapsule pigments include those manufactured by DIC and Toyo Ink.

  Examples of the pigment include a resin-dispersed pigment in which a polymer compound is physically adsorbed or chemically bonded to the pigment.

  Specific pigments such as red, green, brown, white, etc .; metallic luster pigments such as gold and silver; colorless or light extender pigments; plastic pigments; dyes or pigments on the surface of silica, alumina, or polymer beads Insoluble raked dyes; colored emulsions; colored latexes; and the like.

  When a dye is used as the colorant, it is preferable to make the dye into particles together with a polymer dispersant (for example, the specific resin of the present disclosure) and to include the particles in the aqueous ink.

  When the colorant is a granular material, the volume average particle diameter is, for example, 10 nm or more and 200 nm or less.

  The content of the colorant is preferably 1% by mass or more and 25% by mass or less, and more preferably 2% by mass or more and 20% by mass or less with respect to the total mass of the water-based ink.

[Additive]
The water-based ink according to the present embodiment may contain various additives. Examples of the additive include a polymer, a surfactant, a penetrating agent, a viscosity adjusting agent, a pH adjusting agent, a pH buffering agent, an antioxidant, an ultraviolet absorber, an antiseptic, and an antifungal agent. The water-based ink according to this embodiment may contain a compound having infrared absorbing ability other than the compound represented by the general formula (I) and the compound represented by the general formula (II).

[Physical properties of water-based ink]
The volume average particle diameter of the particles contained in the water-based ink is preferably 10 nm or more and 150 nm or less, more preferably 10 nm or more and 120 nm or less, and further preferably 10 nm or more and 100 nm or less. When the volume average particle diameter is 10 nm or more, the light resistance is excellent, and when the volume average particle diameter is 150 nm or less, the droplet ejection characteristics of the ink jet system are excellent. The particle size distribution may be either a wide particle size distribution or a monodisperse particle size distribution.
The volume average particle size and particle size distribution of the particles are measured using a light scattering method.

  The pH of the water-based ink according to this embodiment is preferably 6.5 or more and 10.5 or less, more preferably 7.0 or more and 10.0 or less, and still more preferably 8.0 or more and 10.0 or less. In this embodiment, the pH of the water-based ink is measured under an environment of a temperature of 23 ± 0.5 ° C. and a relative humidity of 55 ± 5%.

  The surface tension of the water-based ink according to this embodiment is preferably 20 mN / m or more and 40 mN / m or less, and more preferably 25 mN / m or more and 35 mN / m or less. In this embodiment, the surface tension of the water-based ink is measured using a Wilhelmy surface tension meter in an environment of a temperature of 23 ± 0.5 ° C. and a relative humidity of 55 ± 5%.

The viscosity of the water-based ink according to the present embodiment is preferably 1 mPa · s to 30 mPa · s, and more preferably 2 mPa · s to 20 mPa · s. In this embodiment, the viscosity of the water-based ink is measured under the conditions of a temperature of 23 ± 0.5 ° C. and a shear rate of 1400 s ⁻¹ using a TV-20 viscometer (Toki Sangyo) as a measuring device.

<Ink cartridge>
The ink cartridge according to the present embodiment is a cartridge that contains the water-based ink according to the present embodiment. The ink cartridge according to the present embodiment is provided in a form that can be attached to and detached from, for example, an ink jet recording apparatus.

<Recording apparatus and recording method>
The recording apparatus according to the present embodiment contains the water-based ink according to the present embodiment, an ink applying unit that applies the water-based ink to the recording medium, and an infrared irradiation unit that irradiates the water-based ink applied to the recording medium with infrared rays. With. The recording apparatus according to the present embodiment realizes a recording method including an ink application process for applying the water-based ink according to the present embodiment to a recording medium, and an infrared irradiation process for irradiating the water-based ink applied to the recording medium with infrared light. Is done.

  Examples of the ink application unit in the present embodiment include: an ejection unit that ejects ink by an inkjet method; an application unit using rolls, sprays, sponges, and the like; a printing unit using offset printing, screen printing, gravure printing, letterpress printing, and the like. It is done.

  The ink application unit in the present embodiment is preferably an ejection unit that ejects ink by an inkjet method. A recording apparatus and a recording method to which the ink jet system is applied are excellent in ejection stability by using the water-based ink according to the present embodiment.

  The recording apparatus according to the present embodiment includes an infrared irradiation unit as a drying unit that dries the aqueous ink applied to the recording medium. In the recording apparatus according to the present embodiment, as the drying means, in addition to the infrared irradiation means, contact-type heating means such as a heating roll, a heating drum, and a heating belt; hot air blowing means including a heating element and a blower; May be provided.

  Examples of the recording medium include paper; paper coated with resin; films and plates made of resin, metal, glass, ceramics, silicon, rubber, and the like.

  The recording apparatus according to the present embodiment may include an ink cartridge that accommodates the water-based ink according to the present embodiment and is made into a cartridge so as to be attached to and detached from the recording apparatus.

  Hereinafter, an example of a recording apparatus and a recording method according to the present embodiment will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating an example of a recording apparatus according to the present embodiment. A recording apparatus 12 shown in FIG. 1 is an ink jet recording apparatus.

  A recording apparatus 12 shown in FIG. 1 includes a container 16 that accommodates a recording medium P before image recording, an endless conveyance belt 28 that is stretched around a driving roll 24 and a driven roll 26, and a housing 14. Ink ejection heads (ink ejection heads 30Y, 30M, 30C, 30K, collectively referred to as ink ejection heads 30), which are examples of ink application means, and infrared irradiation devices (infrared irradiation devices 60Y, 60M, 60C, 60K). And collectively referred to as an infrared irradiation device 60) and a container 40 for storing the recording medium P after image recording.

  Between the container 16 and the transport belt 28 is a transport path 22 through which the recording medium P before image recording is transported. The transport path 22 includes a roll 18 for taking out the recording medium P one by one from the container 16, and a recording. A plurality of roll pairs 20 that convey the medium P are arranged. A charging roll 32 is disposed on the upstream side of the conveyance belt 28. The charging roll 32 is driven while sandwiching the conveyance belt 28 and the recording medium P with the driven roll 26, generates a potential difference with the grounded driven roll 26, and applies an electric charge to the recording medium P to convey the conveyance belt. 28 is electrostatically adsorbed.

  The ink discharge head 30 is disposed above the conveyance belt 28 so as to face the flat portion of the conveyance belt 28. A region where the ink discharge head 30 and the conveyance belt 28 face each other is a region where ink droplets are discharged from the ink discharge head 30.

  Ink discharge heads 30Y, 30M, 30C, and 30K are respectively a head that records a Y (yellow) color image, a head that records an M (magenta) color image, a head that records a C (cyan) color image, and K This is a head for recording a (black) color image. The ink discharge heads 30Y, 30M, 30C, and 30K are arranged from the upstream side to the downstream side of the conveyance belt 28 in this order, for example. The ink ejection heads 30Y, 30M, 30C, and 30K are connected to the ink cartridges 31Y, 31M, 31C, and 31K of each color that are attached to and detached from the recording apparatus 12 through supply tubes (not shown), and the inks of the respective colors are ejected from the ink cartridges. Supplied to the discharge head.

  As the ink discharge head 30, for example, an effective recording area (arrangement area of nozzles that discharge ink) is longer than the width of the recording medium P (the length in the direction orthogonal to the conveyance direction of the recording medium P). And a carriage head that is shorter than the width of the recording medium P and moves in the width direction of the recording medium P to eject ink.

  As the ink jet system employed by the ink ejection head 30, a piezoelectric system that utilizes the vibration pressure of the piezoelectric element; a charge control system that ejects ink using electrostatic attraction; an electrical signal is converted into an acoustic beam and the ink is irradiated And an acoustic ink jet method in which ink is ejected using radiation pressure; a thermal ink jet method in which bubbles are formed by heating the ink and the generated pressure is used; and the like.

  The ink discharge head 30 is, for example, a low-resolution recording head (for example, a 600 dpi recording head) that discharges ink droplets in a range of 10 pL to 15 pL, and discharges ink droplets in a range of less than 10 pL. This is a recording head for high resolution (for example, a recording head of 1200 dpi). dpi means “dots per inch”.

  The recording apparatus 12 is not limited to a form including four ink ejection heads. The recording apparatus 12 may have a form including four or more ink discharge heads obtained by adding intermediate colors to YMCK; a form including one ink discharge head and recording an image of only one color.

  Infrared irradiation means 60Y, 60M, 60C, and 60K are disposed on the downstream side of the ink discharge head 30 above the transport belt 28 for each color ink discharge head. The infrared irradiation device 60 (an example of infrared irradiation means) irradiates the ink on the recording medium P with infrared rays to dry the ink.

  Examples of the light source of the infrared irradiation device 60 include a light emitting diode, a semiconductor laser, a surface emitting semiconductor laser, a halogen lamp, and a xenon lamp.

  As the infrared irradiation device 60, for example, a long infrared irradiation device in which an effective infrared irradiation region (arrangement region of a light source for irradiating infrared rays) is equal to or larger than the width of the recording region by the ink discharge head 30; And a carriage-type infrared irradiation device that moves in the width direction of the recording medium P and irradiates infrared rays.

The irradiation conditions of the infrared irradiation device 60 are set according to the infrared absorption performance of the ink, the amount of water in the ink, and the like. As the irradiation condition, the irradiation condition for drying the water content in the ink applied on the recording medium P to 10% by mass or less is preferable. Specifically, for example, a central wavelength of 700nm or more 1200nm or less (preferably not more than 780nm or 980 nm), irradiation intensity 0.1 J / cm ² or more 10J / cm ² or less (preferably 1 J / cm ² or more 3J / cm ² The irradiation time is from 0.1 milliseconds to 10 seconds (preferably from 10 milliseconds to 100 milliseconds).

  The recording device 12 is not limited to a mode including an infrared irradiation device for each color ink discharge head, and may be a mode including only one infrared irradiation device on the downstream side of the most downstream ink discharge head.

  The recording device 12 may include at least one of a contact-type heating unit and a hot-air blowing unit as an ink drying unit together with the infrared irradiation device 60. The contact-type heating means or hot air blowing means performs drying under conditions that raise the surface temperature of the recording medium to a range of 50 ° C. or higher and 120 ° C. or lower, for example.

  A peeling plate 34 is disposed on the downstream side of the infrared irradiation device 60 so as to face the drive roll 24. The peeling plate 34 peels the recording medium P from the conveyance belt 28.

  Between the conveyance belt 28 and the container 40 is a conveyance path 36 through which the recording medium P after image recording is conveyed, and a plurality of pairs of rolls 38 that convey the recording medium P are arranged in the conveyance path 36. .

The operation of the recording device 12 will be described.
The recording medium P before image recording is taken out one by one from the container 16 by the roll 18 and is conveyed to the conveying belt 28 by the plural roll pairs 20.
Next, the recording medium P is electrostatically attracted to the conveyance belt 28 by the charging roll 32, and is conveyed below the ink discharge head 30 by the rotation of the conveyance belt 28.
Next, ink is ejected from the ink ejection head 30 onto the recording medium P, and an image is recorded.
Next, the ink on the recording medium P is irradiated with infrared rays from the infrared irradiation device 60, the ink generates heat by absorbing infrared rays, the ink temperature rises, and the ink is dried.
Next, the recording medium P on which the ink is dried and the image is fixed is peeled off from the transport belt 28 by the peeling plate 34 and is transported to the container 40 by a plurality of roll pairs 38.

  The recording apparatus according to the present embodiment is not limited to a mode in which ink is directly applied to the recording medium from the ink applying unit, and after the ink is applied from the ink applying unit to the intermediate transfer member, the ink on the intermediate transfer member is applied to the recording medium. A form to be transferred may be used.

  The recording apparatus according to the present embodiment is not limited to a sheet-fed press using the recording apparatus 12 illustrated in FIG. 1 as an example, and may be a rotary press.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. In the following description, “part” and “%” are all based on mass unless otherwise specified.

<Synthesis of Infrared Absorbing Compound>
[Synthesis of Compound (Ia-1)]
Compound (Ia-1) was synthesized according to the following reaction scheme.

  A Dean-Stark trap, a reflux condenser, a stirring seal, and a stirring rod were installed in a three-necked flask to prepare a reaction vessel. 2,2,8,8-Tetramethyl-3,6-nonadiin-5-ol and cyclohexane were placed in a reaction vessel. Manganese (IV) oxide powder was added, stirred with a three-one motor, and heated to reflux. Water formed during the reaction was removed by azeotropic distillation. It was confirmed by thin layer chromatography that there was no 2,2,8,8-tetramethyl-3,6-nonadiin-5-ol remaining. The reaction mixture was allowed to cool and then filtered under reduced pressure to obtain a yellow filtrate (F1). The filtered solid was transferred to another container, ethyl acetate was added, and the operation of ultrasonically dispersing and filtering was repeated 4 times to obtain an ethyl acetate extract (F2). The ethyl acetate extract (F2) and the filtrate (F1) were mixed and concentrated with a rotary evaporator and then with a vacuum pump to obtain an orange liquid. The orange liquid was distilled under reduced pressure to obtain a pale yellow liquid (Intermediate 1).

  A thermometer and a dropping funnel were installed in a three-necked flask to prepare a reaction vessel. Sodium hydrogen monosulfide n hydrate was added to ethanol and stirred at room temperature (20 ° C.) until dissolved, followed by cooling with ice water. When the internal temperature reached 5 ° C., a mixture of intermediate 1 and ethanol was added dropwise little by little. The liquid changed from yellow to orange by the dropwise addition. Since the internal temperature increased due to heat generation, the internal temperature was dropped within the range of 5 ° C. or higher and 7 ° C. or lower while adjusting the dropping amount. Thereafter, the ice water bath was removed, and the mixture was stirred while allowing the temperature to rise naturally at room temperature (20 ° C.). Water was added to the reaction solution, and ethanol was removed by a rotary evaporator. Thereafter, sodium chloride was added until saturation, and the mixture was separated with ethyl acetate to recover the organic phase. The organic phase was washed twice with saturated ammonium chloride and dried over magnesium sulfate. After drying, the solution was concentrated under reduced pressure to recover a brown liquid. The brown liquid was distilled under reduced pressure. A distillate begins to come out at 200 ° C., but since the purity of the target component is low in the initial distillate, the main distillate was selected when the amount of steam increased. A yellow liquid (Intermediate 2) was distilled.

  A stir bar and intermediate 2 were placed in a three-necked flask, and a nitrogen inlet tube and a reflux condenser were attached to replace the nitrogen. Under a nitrogen atmosphere, anhydrous tetrahydrofuran was added with a syringe, and a 1M tetrahydrofuran solution of methylmagnesium bromide was added dropwise with a syringe while stirring at room temperature (20 ° C.). After completion of the dropwise addition, the reaction solution was heated and stirred and refluxed. The reaction solution was allowed to cool under a nitrogen atmosphere, and then a solution of ammonium bromide dissolved in water was added dropwise while cooling in an ice-water bath. The reaction mixture was further stirred at room temperature (20 ° C.), n-hexane was added, and the mixture was dried over sodium sulfate. After drying, the n-hexane / tetrahydrofuran solution was taken out with a syringe and the inorganic layer was washed with ethyl acetate to obtain an extract. The n-hexane / tetrahydrofuran solution and the extract from the inorganic layer were mixed, concentrated under reduced pressure, and then vacuum dried to obtain Intermediate 3.

  Under a nitrogen atmosphere, Intermediate 3 and squaric acid were dispersed in a mixed solvent of cyclohexane and isobutanol, and pyridine was added and heated to reflux. Then isobutanol was added and the reaction mixture was further heated to reflux. Water generated during the reaction was removed by azeotropic distillation. The reaction mixture was allowed to cool and then filtered under reduced pressure to remove hardly soluble substances. The filtrate was concentrated on a rotary evaporator. Methanol was added to the residue, heated to 40 ° C, and then cooled to -10 ° C. Crystals were obtained by filtration, and this was vacuum-dried to obtain compound (I-a-1).

[Synthesis of Compound (Ia-4)]
Except that 4,7-dodecadiin-6-ol was used instead of 2,2,8,8-tetramethyl-3,6-nonadiin-5-ol in the synthesis of compound (Ia-1). Compound (Ia-4) was synthesized in the same procedure.

<Polymer synthesis>
[Synthesis of Polymer P41]
In a 0.5 liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 25.0 parts of methyl ethyl ketone was charged and heated to 80 ° C. While maintaining the temperature in the reaction vessel at 80 ° C., a mixed solution composed of the following monomers, 70 parts of methyl ethyl ketone, and 1.6 parts of a polymerization initiator “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) Dropped over time. After completion of the dropwise addition, a solution consisting of 0.4 parts of “V-601” and 10.0 parts of methyl ethyl ketone was added, stirred at 80 ° C. for 2 hours, and further 0.4 parts of “V-601” and 10.0 parts of methyl ethyl ketone. Part of the solution was added, and the mixture was stirred at 80 ° C. for 2 hours, then heated to 85 ° C., and further stirred for 2 hours to obtain a polymer P41 solution.
-Monomer-
・ Isobornyl methacrylate (IBOMA, manufactured by Wako Pure Chemical Industries, Ltd.) 30.0 parts ・ Methyl methacrylate (MMA, manufactured by Wako Pure Chemical Industries, Ltd.) 42.0 parts ・ Styrene (St, Wako Pure Chemical Industries, Ltd. ( Co., Ltd.) 20.0 parts • Methacrylic acid (MAA, Wako Pure Chemical Industries, Ltd.) 8.0 parts

  The obtained polymer P41 had a weight average molecular weight (Mw) of 32000 (calculated in terms of polystyrene by GPC), an acid value of 52 (mgKOH / g), and a solid content concentration of 48%.

[Synthesis of Polymers P41-1, P41-2, P41-3, P05, P11, P13, P17, H02, P06, P06-1, P06-2, and P06-3]
According to Tables 1 to 3, except that the types and amounts of the monomers were changed, the same as in the synthesis of the polymer P41, the polymers P41-1, P41-2, P41-3, P05, P11, P13, P17, P06, Solutions of P06-1, P06-2, P06-3, and H02 were obtained.

[Synthesis of Polymer P44]
In a 0.5 liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, 10.0 parts of ethanol was charged and the temperature was raised to 80 ° C. A mixture comprising the following monomer, 60 parts of ethanol, 6 parts of water, and 1.0 part of a polymerization initiator “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) while maintaining the temperature in the reaction vessel at 80 ° C. The solution was added dropwise over 2 hours. After completion of the dropwise addition, a solution consisting of 0.2 part of “V-601” and 10.0 parts of methyl ethyl ketone was added, stirred at 80 ° C. for 2 hours, and then 0.2 part of “V-601” and 10.0 parts of methyl ethyl ketone. Part of the solution was added, and the mixture was stirred at 80 ° C. for 2 hours, then heated to 85 ° C., and further stirred for 2 hours to obtain a polymer P44 solution.
-Monomer-
・ 4.0 parts of 2-acrylamido-2-methylpropanesulfonic acid (Wako Pure Chemical Industries, Ltd.) ・ 30.0 parts of dicyclopentanyl methacrylate (Hitachi Chemical Co., Ltd.) ・ Styrene (Wako Pure Chemical Industries, Ltd.) (Made by Co., Ltd.) 20.0 parts Methyl methacrylate (Wako Pure Chemical Industries, Ltd.) 46.0 parts

  The obtained polymer P44 had a weight average molecular weight (Mw) of 26000 (calculated by GPC in terms of polystyrene), an acid value of 11 (mgKOH / g), and a solid content concentration of 48%. The average content (crosslinked alicyclic group content) (mass%) in the polymer molecular structure of the bridged alicyclic group is shown in Table 1 below.

[Synthesis of Polymers P44-1, P44-2, P47, and H01]
A solution of polymers P44-1, 44-2, P47, and H01 was obtained in the same manner as the synthesis of polymer P44 except that the type and amount of the monomer were changed according to Tables 1 and 2.

<Manufacture of dispersion>
[Production of Particle Dispersion (AD-1)]
To 2.1 g of the polymer P41 solution, 2.0 ml of methyl ethyl ketone (MEK) is added and stirred, so that a 10% aqueous solution of sodium hydroxide neutralizes 0.8 equivalent of the total amount of carboxylic acid contained in the polymer P41. Was added with stirring. To this solution, 40 mg of the compound (I-a-1) and 1.0 ml of tetrahydrofuran (THF) were added and dissolved. While continuing to stir, 12 ml of water was gradually added.
Next, a distillation tube and a vacuum pump were attached to the flask, and the solution was heated to 30 ° C. or higher and 35 ° C. or lower and the pressure was reduced while stirring to distill off part of the organic solvent and water. In the middle, the operation of adding water and concentrating so that the solid content concentration did not exceed 13% was repeated until the organic solvent odor disappeared. The concentrated solution was filtered through a 0.45 μm filter to obtain a dispersion.
About this dispersion liquid, the "yield" (solid content) was calculated | required by the method mentioned later. Based on the measured solid content, water was added to this dispersion to adjust the solid concentration to 10% by mass, and a particle dispersion (AD-1) was obtained.
When converted from the amount of the compound (I-a-1) and the amount of polymer used for the production of the particle dispersion (AD-1), the concentration of the compound (I-a-1) in the particle dispersion (AD-1) is It was 0.4 mass%.

[Particle dispersions (production of AD-2 to AD-4, AD-8 to AD-11, and AD-16]
In the production of the particle dispersion (AD-1), the particle dispersions (AD-2 to AD-4, AD-8 to AD-11) were similarly obtained except that the polymer was changed as shown in Tables 1 and 2. , And AD-16).

[Production of Particle Dispersion (AD-5)]
To 2.1 g of the polymer P44 solution, 2.0 ml of methyl ethyl ketone (MEK) was added and stirred. To this solution, 40 mg of the compound (I-a-1) and 1.0 ml of tetrahydrofuran (THF) were added and dissolved. While continuing to stir, 12 ml of water was gradually added.
Next, a distillation tube and a vacuum pump were attached to the flask, and the solution was heated to 30 ° C. or higher and 35 ° C. or lower and the pressure was reduced while stirring to distill off part of the organic solvent and water. In the middle, the operation of adding water and concentrating so that the solid content concentration did not exceed 13% was repeated until the organic solvent odor disappeared. The dispersion was filtered through a 0.45 μm filter to obtain a particle dispersion (AD-5) containing 0.4% by mass of the compound (Ia-1) and having a solid content concentration of 10%.

[Particle dispersion (production of AD-6 to AD-7 and AD-12)]
Particle dispersions (AD-6 to AD-7 and AD-12) were obtained in the same manner except that the polymer was changed as shown in Tables 1 and 2 in the production of the particle dispersion (AD-5). It was.

[Production of particle dispersions (AD-13 to AD-15)]
In the production of the particle dispersion liquid (AD-1), the particle dispersion liquids (AD-13 to AD-15) were similarly obtained except that the types of compounds and polymers were changed as shown in Tables 1 and 2. Got.
In addition, the compound II used for the particle dispersion (AD-15) is the following compound (absorption wavelength: 847 nm, gram absorption 212).

[Production of Particle Dispersion (AD-17)]
In the production of the particle dispersion (AD-15), a particle dispersion (AD-17) was obtained in the same manner except that the type of polymer was changed as shown in Table 2.

[Production of Particle Dispersion (AD-18)]
In the production of the particle dispersion (AD-17), a particle dispersion (AD-18) was obtained in the same manner except that the type of the compound was changed as shown in Table 2.
Compound III used in the particle dispersion (AD-18) is the following compound (absorption wavelength 795 nm, gram absorption 245).

[Production of particle dispersions (AD-19 to AD-23)]
In the production of the particle dispersion (AD-1), particle dispersions (AD-19 to AD-23) were obtained in the same manner except that the polymer was changed as shown in Tables 2 and 3.

[Evaluation]
(yield)
In a 5 cm diameter aluminum cup, each particle dispersion obtained above was weighed in a range of 0.6 g or more and 0.8 g or less, heated at 120 ° C. for 2 hours under atmospheric pressure, and then measured for the mass of solids. The solid content in the dispersion was determined. The mass obtained by neutralizing the polymer used in the preparation of the dispersion with sodium hydroxide was calculated, and the yield was determined by the following formula. From this yield, it evaluated according to the following evaluation criteria.
Yield = (Solid content in dispersion) / (mass of polymer neutralized with sodium hydroxide)
-Evaluation criteria-
A: 90% by mass or more B: 80% by mass or more and less than 90% by mass C: 70% by mass or more and less than 80% by mass D: Less than 70% by mass

(Particle size)
The volume average particle diameter (median diameter) of the particles was measured using a dynamic light scattering particle size distribution analyzer LP-500 (Horiba, Ltd.).

(Infrared absorption)
Each particle dispersion obtained as described above was stored at 50 ° C. for 1 day, diluted 1600 times, put in a quartz cell having an optical path length of 1 cm, and measured for an absorption spectrum to obtain an absorbance value at a wavelength of 818 nm.
-Evaluation criteria-
A: Absorbance 0.7 or more B: Absorbance 0.5 or more, less than 0.7 C: Absorbance 0.3 or more, less than 0.5 D: Less than 0.3

  “Bridged alicyclic group content” described in Tables 1 to 3 represents an average content (% by mass) in the polymer molecular structure of the bridged alicyclic group.

Details of various monomers shown in Tables 1 to 3 are as follows.
Monomers having bridged alicyclic groups IBOMA: Isobornyl methacrylate DCPMA: Dicyclopentanyl methacrylate DCPA: Dicyclopentenyl acrylate Other monomers PhOEMA: Phenoxyethyl methacrylate St: Styrene BzA: Benzyl acrylate MMA: Methyl Methacrylate EMA: Ethyl methacrylate cHMA: Cyclohexyl methacrylate-Monomer that gives acid value CEA: Shipomer β-CEA (2-carboxyethyl acrylate)
MAA: methacrylic acid AMPS: 2-acrylamido-2-methylpropanesulfonic acid NaSS: sodium styrenesulfonate

As shown in Tables 1 to 3, in the samples (AD-4) and (AD-7) where the acid value of the polymer is less than 6 mgKOH / g or greater than 100 mgKOH / g, a stable dispersion cannot be obtained and the yield is low. It was low.
In addition, in the sample (AD-15) using the compound II that does not correspond to either the compound represented by the general formula (I) or the compound represented by the general formula (II), the particle size of the produced particles is Samples (AD-15) and (AD-17) using Compound II or Compound III which is large and does not correspond to any of the compound represented by General Formula (I) and the compound represented by General Formula (II) In (AD-18), the amount of infrared absorption was small.

<Preparation of water-based ink composition>
(Preparation of cyan dispersion)
In a reaction vessel, 6 parts of styrene, 11 parts of stearyl methacrylate, 4 parts of styrene macromer AS-6 (manufactured by Toagosei), 5 parts of Plenmer PP-500 (manufactured by NOF Corporation), 5 parts of methacrylic acid, 0.05 of 2-mercaptoethanol A mixed solution a of 24 parts of methyl ethyl ketone was prepared.
On the other hand, 14 parts of styrene, 24 parts of stearyl methacrylate, 9 parts of styrene macromer AS-6 (manufactured by Toa Gosei), 9 parts of Plenmer PP-500 (manufactured by NOF), 10 parts of methacrylic acid, 0.13 part of 2-mercaptoethanol, A mixed solution b consisting of 56 parts of methyl ethyl ketone and 1.2 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) was prepared and placed in a dropping funnel.
Next, the mixed solution a in the reaction vessel was heated to 75 ° C. with stirring under a nitrogen atmosphere, and the mixed solution b in the dropping funnel was gradually dropped over 1 hour. After 2 hours from the end of dropping, 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, The solution was aged at 80 ° C. for 2 hours to obtain a methyl ethyl ketone solution of a water-insoluble polymer dispersant.
A part of the obtained water-insoluble polymer dispersant solution was isolated by removing the solvent, the obtained solid content was diluted to 0.1% with tetrahydrofuran, and the weight average molecular weight was measured by GPC. As a result, the isolated solid content had a polystyrene equivalent weight average molecular weight of 25,000.
The obtained water-insoluble polymer dispersant solution was 5.0 parts in terms of solid content, 10.0 parts of cyan pigment pigment blue 15: 3 (manufactured by Dainichi Seika), 40.0 parts of methyl ethyl ketone, and 1 mol / L hydroxylation. 8.0 parts of sodium, 82.0 parts of ion-exchanged water, and 300 parts of 0.1 mm zirconia beads were supplied to the vessel and dispersed with a ready mill disperser (manufactured by Imex) at 1000 rpm for 6 hours. The obtained dispersion was concentrated under reduced pressure until the methyl ethyl ketone was sufficiently distilled off with an evaporator, concentrated until the pigment concentration was 10%, and water-insoluble colored particles composed of a pigment whose surface was coated with a water-insoluble polymer dispersant, Cyan dispersion CD1 was obtained.
The average particle diameter of the cyan pigment in the obtained cyan dispersion CD1 was 77 nm.

(Preparation of cyan ink C-1)
The ink was prepared so as to have the following ink composition. After the preparation, coarse particles were removed with a 5 μm filter, and cyan ink C-1 was prepared as an aqueous ink composition.
・ Cyan dispersion CD1 ・ ・ 6%
・ Particle dispersion (AD-1) (solid content conversion) ・ 2.5%
・ Propylene glycol (made by Wako Pure Chemical Industries) ・ ・ 25%
・ Propylene glycol monobutyl ether ・ ・ 3%
・ Olfin E1010 (Nissin Chemical Industry) ・ ・ 0.7%
・ Orphine E1004 (Nissin Chemical Industry) ・ ・ 0.3%
・ Ion-exchanged water added to make the total 100%

(Preparation of cyan inks C-2 to C-21)
In the preparation of cyan ink C-1, the cyan ink C-1 was prepared in the same manner as the preparation of cyan ink C-1, except that the particle dispersion (AD-1) was changed as shown in Tables 4 and 5 below. -2 to C-21 were obtained.

[Print evaluation test]
The cyan inks C-1 to C-21 immediately after preparation were refilled into cartridges of an Epson inkjet printer PX-1004, and printed on Tokishi Art Duplex N (Mitsubishi Paper) with the inkjet printer PX-1004. In all of C-1 to C-21, there was no ejection failure and good printing could be performed.
Next, the formed image was irradiated with infrared rays under the conditions of a center wavelength of 810 nm, an irradiation intensity of 3 J / cm ² , and an irradiation time of 200 milliseconds, and it was visually observed whether or not the image was dry.
-Evaluation criteria-
A (○): Blur by visual observation B (x): Blur by visual observation

[Concentrated redispersibility]
The obtained cyan inks C-1 to C-21 were placed in a glass petri dish, heated at 40 ° C., and concentrated to 40% (that is, 60% of water was evaporated). Thereafter, ion-exchanged water was added again for dilution, and the state of this diluted solution was visually observed and evaluated based on the following evaluation criteria.
-Evaluation criteria-
A: Almost no solid matter on the petri dish and almost no aggregates in the diluted solution B: Little solid matter on the petri dish and a small amount of aggregates in the diluted solution C: There is a small amount of solid matter on the petri dish , There are aggregates in the diluted solution D: more than half of the solids remain on the petri dish

As shown in Table 4 and Table 5, a particle dispersion (AD-) using Compound II or Compound III that does not correspond to any of the compound represented by General Formula (I) and the compound represented by General Formula (II) 15) In the cyan inks C-13, C-15, and C-16 using (AD-17) and (AD-18), blurring was visually observed in the formed image.
Further, cyan inks C-14 and C-17 using polymers H01 or H02 not containing a structural unit having a bridging alicyclic group as the polymer were inferior in concentration and redispersibility.

12 recording device 14 housing 16 container 18 roll 20 roll pair 22 transport path 24 drive roll 26 driven roll 28 transport belts 30Y, 30M, 30C, 30K ink ejection head (an example of ink applying means)
31Y, 31M, 31C, 31K Ink cartridge 32 Charging roll 34 Release plate 36 Transport path 38 Roll pair 40 Container 60Y, 60M, 60C, 60K Infrared irradiation device (an example of infrared irradiation means)
P Recording medium

Claims (7)

An aqueous medium, and
An alkyl (meth) acrylate that contains at least one compound represented by the following general formula (I) and the following general formula (II) and contains an alicyclic hydrocarbon group having a bridging bond, is dispersed in the aqueous medium. Particles containing a resin having a unit and an acid value of 6 mgKOH / g or more and 100 mgKOH / g or less,
A particle dispersion containing


(In general formula (I), R ^1a , R ^1b , R ^1c and R ^1d each independently represents an alkyl group or an aryl group.
In general formula (II), R ^2a , R ^2b , R ^2c and R ^2d each independently represents an alkyl group. R ^2a and R ^2b and R ^2c and R ^2d may be independently connected to form a ring. )   2. The particle dispersion according to claim 1, wherein an average content of the alicyclic hydrocarbon group having a crosslinking bond in the molecular structure of the resin is 7% by mass or more and 50% by mass or less.   The particle dispersion according to claim 1, wherein the alicyclic hydrocarbon group having a bridging bond is a group having a bicyclo ring structure or a tricyclo ring structure. An aqueous medium, and
An alkyl (meth) acrylate that contains at least one compound represented by the following general formula (I) and the following general formula (II) and contains an alicyclic hydrocarbon group having a bridging bond, is dispersed in the aqueous medium. Particles containing a resin having a unit and an acid value of 6 mgKOH / g or more and 100 mgKOH / g or less,
Water-based ink containing.


(In general formula (I), R ^1a , R ^1b , R ^1c and R ^1d each independently represents an alkyl group or an aryl group.
In general formula (II), R ^2a , R ^2b , R ^2c and R ^2d each independently represents an alkyl group. R ^2a and R ^2b and R ^2c and R ^2d may be independently connected to form a ring. )   An ink cartridge containing the water-based ink according to claim 4. Ink applying means for containing the water-based ink according to claim 4 and applying the water-based ink to a recording medium;
Infrared irradiation means for irradiating the aqueous ink applied to the recording medium with infrared rays;
A recording apparatus comprising: An ink application step of applying the water-based ink according to claim 4 to a recording medium;
An infrared irradiation step of irradiating the water-based ink applied to the recording medium with infrared rays;
A recording method.