JP2018193477A - Particle dispersion, aqueous ink, ink cartridge, recording apparatus and recording method - Google Patents

Abstract

To provide a particle dispersion excellent in condensation redispersibility.SOLUTION: The particle dispersion contains: particles containing a polymer and at least one of compounds represented by general formulas (I) and (II), and two water-soluble organic solvents having specific SP values.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.

  An aqueous ink containing an infrared absorber is known as an aqueous ink that is fixed to a recording medium by light irradiation.

  For example, Patent Document 1 discloses an ink composition containing water, an organic pigment, a polymer dispersant for dispersing a near-infrared absorbing dye, and a water-insoluble near-infrared absorbing dye having an absorption maximum wavelength of 700 nm to 1500 nm. Things are disclosed.

  For example, Patent Document 2 discloses an aqueous coating composition containing a latex impregnated with an infrared absorbing compound and an aqueous polyester.

  For example, Patent Document 3 discloses an inkjet ink containing water, two water-soluble organic solvents having a SP value difference of 3 or more calculated by the Fedors method, a pigment, and resin particles.

Japanese Patent Application Laid-Open No. 2014-0473302 JP 2003-107624 A Japanese Patent Laying-Open No. 2006-053129

  2. Description of the Related Art Conventionally, in order to contain an infrared absorber in an aqueous medium, a particle dispersion liquid in which an infrared absorber and a polymer are formed into particles containing both and dispersed in an aqueous medium is known. When the particle dispersion is used for, for example, an aqueous ink for an ink jet method (droplet discharge method), it is required to have excellent concentration redispersibility from the viewpoint of suppressing clogging at the discharge port (inkjet head). Even when the particle dispersion is used in addition to the water-based ink for the ink jet system, concentrated redispersibility is required from the viewpoint of dispersion stability accompanying changes in the surrounding temperature environment. Concentrated redispersibility means the dispersibility of solid content when diluted with a solvent after at least a part of the solvent of the dispersion is evaporated and the dispersion is concentrated.

  An object of the present invention is to provide a particle dispersion excellent in concentrated redispersibility.

  Specific means for solving the above-described problems include the following modes.

The invention according to claim 1
water and,
Particles containing at least one compound selected from a compound represented by the following general formula (I) and a compound represented by the following general formula (II) and a polymer;
A first water-soluble organic solvent having an SP value calculated by the Okitsu method of 24 or more and less than 27;
A second water-soluble organic solvent having an SP value of 27 or more and 32 or less calculated by the Okitsu method;
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, and R ^2a and R ^2b and R ^2c and R ^2d are each independently connected to form a ring. May be.

The invention according to claim 2
The particle dispersion liquid according to claim 1, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (Ia).

In general formula (Ia), R ^a represents a group represented by general formula (Ib), and R ^b , R ^c, and R ^d each independently represents an alkyl group. In the general formula (I-b), ^{R e} represents hydrogen or a methyl group, n represents an integer of 0 to 3.

The invention according to claim 3
The particle dispersion according to claim 1 or 2, wherein the second water-soluble organic solvent contains at least one of ethylene glycol and 2-pyrrolidone.

The invention according to claim 4
The particle dispersion according to any one of claims 1 to 3, wherein the polymer contains at least one selected from polyurethane, polyester, polyamide, polyurea and polycarbonate.

The invention according to claim 5
water and,
Particles containing at least one compound selected from a compound represented by the following general formula (I) and a compound represented by the following general formula (II) and a polymer;
A first water-soluble organic solvent having an SP value calculated by the Okitsu method of 24 or more and less than 27;
A second water-soluble organic solvent having an SP value of 27 or more and 32 or less calculated by the Okitsu method;
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, and R ^2a and R ^2b and R ^2c and R ^2d are each independently connected to form a ring. May be.

The invention according to claim 6
The water-based ink according to claim 5, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (Ia).

In general formula (Ia), R ^a represents a group represented by general formula (Ib), and R ^b , R ^c, and R ^d each independently represents an alkyl group. In the general formula (I-b), ^{R e} represents hydrogen or a methyl group, n represents an integer of 0 to 3.

The invention according to claim 7 provides:
The water-based ink according to claim 5 or 6, wherein the second water-soluble organic solvent contains at least one of ethylene glycol and 2-pyrrolidone.

The invention according to claim 8 provides:
The water-based ink according to any one of claims 5 to 7, wherein the polymer contains at least one selected from polyurethane, polyester, polyamide, polyurea and polycarbonate.

The invention according to claim 9 is:
The aqueous solution according to any one of claims 5 to 8, wherein a total of the first water-soluble organic solvent and the second water-soluble organic solvent is 18 to 36% by mass of the entire aqueous ink. ink.

The invention according to claim 10 is:
The aqueous solution according to any one of claims 5 to 9, wherein the total of the first water-soluble organic solvent and the second water-soluble organic solvent is 20 to 35 mass% of the entire aqueous ink. ink.

The invention according to claim 11 is:
The aqueous ink according to any one of claims 5 to 10, wherein the second water-soluble organic solvent is 2 to 16% by mass of the entire aqueous ink.

The invention according to claim 12
The water-based ink according to any one of claims 5 to 11, wherein the second water-soluble organic solvent is 3 to 11% by mass of the entire water-based ink.

The invention according to claim 13 is:
An ink cartridge containing the water-based ink according to any one of claims 5 to 12.

The invention according to claim 14 is:
An ink application unit that contains the water-based ink according to any one of claims 5 to 12 and that applies the water-based ink to a recording medium;
Infrared irradiation means for irradiating the water-based ink applied to the recording medium with infrared rays;
A recording apparatus comprising:

The invention according to claim 15 is:
The recording apparatus according to claim 14, wherein the ink applying unit includes an ink jet head that discharges the water-based ink, and is a unit that discharges the water-based ink from the ink-jet head and applies the water-based ink to a recording medium.

The invention according to claim 16 provides:
An ink application step for applying the water-based ink according to any one of claims 5 to 12 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.

The invention according to claim 17 provides:
The recording method according to claim 16, wherein the ink applying step is a step of discharging the water-based ink from an ink jet head and applying the ink to a recording medium.

  According to the invention according to claim 1, 2, 3 or 4, compared to the particle dispersion not containing one of the first water-soluble organic solvent and the second water-soluble organic solvent, it is more concentrated and redispersible. An excellent particle dispersion is provided.

According to the invention according to claim 5, 6, 7, or 8, the concentrated redispersibility is excellent as compared with a water-based ink that does not contain one of the first water-soluble organic solvent and the second water-soluble organic solvent. An aqueous ink is provided.
According to the invention according to claim 9 or 10, the concentration of the first water-soluble organic solvent and the second water-soluble organic solvent is higher than that of the water-based ink in which the total amount of the water-based ink is less than 18% by mass. An aqueous ink excellent in redispersibility is provided.
According to the invention which concerns on Claim 11 or 12, compared with the water-based ink whose said 2nd water-soluble organic solvent is less than 2 mass% of the whole water-based ink, the water-based ink excellent in concentration redispersibility is provided.

According to the invention of claim 13, an ink containing a water-based ink that is superior in concentration and redispersibility compared to a water-based ink that does not include one of the first water-soluble organic solvent and the second water-soluble organic solvent. A cartridge is provided.
According to the invention according to claim 14 or 15, a water-based ink that is superior in concentration and redispersibility compared to a water-based ink that does not contain one of the first water-soluble organic solvent and the second water-soluble organic solvent is used. A recording device is provided.
According to the invention which concerns on Claim 16 or 17, compared with the water-based ink which does not contain one of said 1st water-soluble organic solvent and said 2nd water-soluble organic solvent, the water-based ink which is excellent in concentration re-dispersibility is used. A recording method is 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, numerical ranges indicated using “to” indicate ranges including numerical values described before and after “to” as the minimum value and the maximum value, respectively.

<Particle dispersion, water-based ink>
The particle dispersion according to this embodiment includes water, particles containing at least one compound selected from a compound represented by the general formula (I) and a compound represented by the general formula (II), and a polymer; The first water-soluble organic solvent having an SP value calculated by the above formula of 24 or more and less than 27, and the second water-soluble organic solvent having an SP value calculated by the Okitsu method of 27 or more and 32 or less.

  The water-based ink according to the present embodiment includes water, particles containing at least one compound selected from the compound represented by the general formula (I) and the compound represented by the general formula (II), and a polymer, and an Okitsu method. A first water-soluble organic solvent having a calculated SP value of 24 or more and less than 27; and a second water-soluble organic solvent having an SP value of 27 or more and 32 or less calculated by the Okitsu method.

  The compound represented by the general formula (I) and the compound represented by the general formula (II) are compounds having infrared absorption ability. Hereinafter, the compound represented by the general formula (I) and the compound represented by the general formula (II) may be collectively referred to as “specific infrared absorber”. Particles containing at least one compound selected from the compound represented by formula (I) and the compound represented by formula (II) and a polymer may be referred to as “specific particles”.

The particle dispersion and aqueous ink according to the present embodiment are excellent in concentrated redispersibility. As this mechanism, the first water-soluble organic solvent having a relatively low SP value has an affinity for the polymer, so that it exists around the specific particle and acts as a dispersant for the particle. In addition, it is presumed that the second water-soluble organic solvent having a high SP value mediates between the first water-soluble organic solvent and water, thereby improving the redispersibility of specific particles in water.
In a water-soluble organic solvent having an SP value of less than 24, the polymer constituting the specific particles is easily dissolved, and it may be difficult to stably disperse the specific particles.
A water-soluble organic solvent having an SP value of more than 32 affects the stability of the specific infrared absorber in an aqueous medium, and may reduce the infrared absorption performance of the particle dispersion and aqueous ink.

  For example, when the water-based ink according to the present embodiment is applied to an ink jet recording apparatus, the ink can be redispersed when the ink is ejected again even if it is concentrated in the ink jet head. Secured.

  Hereinafter, components, compositions, production methods, and the like of the particle dispersion and the aqueous ink according to the present embodiment will be described in detail.

[water]
The particle dispersion and the water-based ink according to the present embodiment use 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.

  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.

  The content of water is preferably 40 to 75% by mass, more preferably 45 to 70% by mass, and still more preferably 50 to 65% by mass with respect to the total mass of the particle dispersion or aqueous ink.

[Specific particles]
In this embodiment, the specific particle contains at least a specific infrared absorber and a polymer.

-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, the phenyl group may be substituted with one alkyl group or a plurality of alkyl groups, but an alkyl-substituted phenyl group in which one alkyl group is substituted is more preferable. . The alkyl group as a substituent is preferably an alkyl group having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a 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 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-decyl group and the like.

  Specific examples of the aryl group include a phenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-propylphenyl group, 4-butylphenyl group (preferably 4-tert-butylphenyl group), 3-methyl A phenyl group, 2-methylphenyl group, etc. are mentioned, A phenyl group is especially 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).

  Specific examples of the compound represented by the general formula (I) include the following compounds (I-1) to (I-5).

-Compound represented by general formula (Ia)-
As the compound represented by the general formula (I), a compound represented by the following general formula (Ia) is preferable.

In general formula (Ia), R ^a represents a group represented by general formula (Ib), and R ^b , R ^c, and R ^d each independently represents an alkyl group. In the general formula (I-b), ^{R e} represents hydrogen or a methyl group, n represents an integer of 0 to 3.

  The compound represented by the general formula (Ia) is unlikely to deteriorate in infrared absorption performance even when stored for a long period of time or at a high temperature. The following is presumed as this mechanism.

A compound having a squarylium skeleton is contained in an aqueous composition such as a photofixable ink for reasons such as high infrared absorption performance, but the squarylium skeleton is decomposed by a solvent and other materials (dispersant, surfactant, etc.). There are things to do.
In contrast, in the compound represented by the general formula (Ia), at least one of the four alkyl groups is a branched alkyl group having 3 or more carbon atoms, and the branched alkyl group is considered to protect the squarylium skeleton. It is done. Therefore, the compound represented by the general formula (Ia) is unlikely to be decomposed in the aqueous composition, and it is presumed that the infrared absorption performance is not easily lowered even when stored for a long period of time or at a high temperature.

In general formula (Ib), 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 (Ib) 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. This is because the structure in which R ^e is a methyl group is less likely to have a solvent and other materials (dispersant, surfactant, etc.) close to the squarylium skeleton than the structure in which R ^e is hydrogen. This is considered to be because the decomposition of the compound represented by -a) is suppressed.

  In general formula (Ib), n represents the integer of 0-3. n is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0. The smaller n is, the lower the infrared absorption performance is suppressed. This is because the smaller the value of n, the closer the distance between the branched structure portion in the group represented by the general formula (Ib) and the squarylium skeleton, so that the solvent and other materials (dispersant, surfactant) Etc.) are less likely to approach the squarylium skeleton, and it is considered that the decomposition of the compound represented by the general formula (Ia) is suppressed.

  The total number of carbon atoms of the group represented by the general formula (Ib) 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.

  Specific examples of the group represented by the general formula (Ib) include isopropyl group, isobutyl group, tert-butyl group, 3-methylbutyl group (3-methylbutan-1-yl group), 2,2-dimethylpropyl group. 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 more preferable.

In the general formula (Ia), R ^b , R ^c and R ^d each independently represents an alkyl group. At least one of R ^b , R ^c and R ^d is preferably a group represented by the general formula (Ib), and all of R ^b , R ^c and R ^d are represented by the general formula (Ib). It is more preferred that As the number of groups represented by the general formula (Ib) in the general formula (Ia) is larger, the decrease in the infrared absorption performance is further suppressed. This is because as the number of groups represented by the general formula (Ib) increases, the solvent and other materials (dispersant, surfactant, etc.) are less likely to approach the squarylium skeleton, and are represented by the general formula (Ia). This is thought to be due to the suppression of decomposition of the compounds.

When one of R ^b , R ^c and R ^d is a group represented by the general formula (Ib), any of R ^b , R ^c and R ^d is represented by the general formula (Ib). It may be a group. When two of R ^b , R ^c and R ^d are groups represented by the general formula (Ib), any of R ^b , R ^c and R ^d is represented by the general formula (Ib). It may be a group.

When two or more of R ^{a to} R ^d are groups represented by the general formula (Ib), a plurality of groups represented by the general formula (Ib) have the same structure or different structures. It may be.

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

The alkyl group in the case where at least one of R ^b , R ^c, and R ^d is other than the group represented by the general formula (Ib) 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 methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, sec-butyl, 2-methylbutan-2-yl, 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 of the compound represented by formula (Ia) are shown below. Compounds (Ia-1) to (Ia-7), Compounds (Ib-1) to (Ib-21), Compounds (Ic-1) to (Ic-21) Is a compound having four groups represented by general formula (Ib). Compounds (Id-1) to (Id-4) are compounds having two groups represented by formula (Ib).

  Among the above specific examples, compounds (Ia-1) to (Ia-7), compounds (Ib-1) to (Ib-6), compounds (Ic-1) to (Ic-6) is preferred, Compound (Ia-1), Compound (Ib-3), and Compound (Ic-3) are more preferred, and Compound (Ia-1) is most preferred preferable.

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

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

A compound in which three of R ^{a to} R ^d 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.

The maximum absorption wavelength (λ _max ) of the compound represented by the general formula (Ia) (tetrahydrofuran solution) is preferably a wavelength of 760 to 1200 nm, more preferably a wavelength of 780 to 1100 nm, and still more preferably a wavelength of 800 to 1000 nm.

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

-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, and R ^2a and R ^2b and R ^2c and R ^2d are each independently connected 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.

When R ^2a and R ^2b are linked to form a ring, or R ^2c and R ^2d are linked to form a ring, the formed ring is a 5-membered ring, 6-membered ring, or 7 A membered ring is preferable, and a 6-membered ring is more preferable. The ring formed may have a substituent, and examples of the substituent include an alkyl group. Examples of the ring structure include cyclopentane, cyclohexane, cycloheptane, 3,5-dimethylcyclohexane, 3,5-diethylcyclohexane, 3,5-diisopropylcyclohexane, 3,3,5-trimethylcyclohexane, and 3,3,5, 5-tetramethylcyclohexane and the like can be mentioned.

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) include the following compounds (II-a-1) to (II-a-7).

Specific examples of the compound in which R ^2a and R ^2b and R ^2c and R ^2d are linked to form a ring in the general formula (II) include, for example, the following compounds (II-b-1) to (II-b-7) Is mentioned.

  The specific particle is a compound having infrared absorbing ability other than the specific infrared absorber (for example, squarylium dye, croconium dye, naphthalocyanine dye, cyanine dye, aminium dye, etc.), a compound having ultraviolet absorbing ability (for example, Benzotriazole compounds, benzophenone compounds, etc.).

-Polymer-
Examples of the polymer contained in the specific particle include a polymer having a dissociable group and being dispersed in an aqueous medium by the action of the dissociable group; an action of the group having a non-dissociable dispersible group (for example, a polyethyleneoxy group) A polymer dispersed in an aqueous medium. The polymer may be a polymer dispersed in an aqueous medium in a liquid state or a polymer dispersed in an aqueous medium in a solid state. From the viewpoint of dispersion stability, a polymer dispersed in an aqueous medium in a solid state is preferable.

  The polymer preferably has a dissociable group from the viewpoint of dispersibility in an aqueous medium. Examples of the dissociable group include a carboxy group, a sulfonic acid group, a sulfinic acid group, a sulfuric monoester group, a phosphoric acid group, or salts thereof (for example, alkali metal salts such as Na and K, ammonia, dimethylamine, ethanolamine, Anionic groups such as diethanolamine, triethanolamine, and ammonium salts such as trimethylamine); and cationic groups such as primary, secondary, tertiary amine, and quaternary ammonium salts. Among these, an anionic group is preferable, and a carboxy group and a sulfonic acid group are particularly preferable.

  The dissociable group in the polymer may be a group in which a group of the raw material monomer is introduced as a side chain of the polymer, a group remaining as an unreacted terminal of the main chain, or a reactive group remaining after polymerization of the polymer (for example, , A hydroxyl group, an amino group) or a group introduced by reacting a compound (for example, maleic anhydride).

  The polymer is preferably at least one selected from the group consisting of polyurethane, polyester, polyamide, polyurea and polycarbonate. Among these, polyurethane and polyester are preferable from the viewpoint of easy introduction of the dissociable group and good compatibility with the specific infrared absorber. 1 type may be used for a polymer and it may use 2 or more types together.

-Polyurethane-
Polyurethane is generally synthesized by a polyaddition reaction between a diol and a diisocyanate.

  The polyurethane preferably has a dissociable group from the viewpoint of dispersibility in an aqueous medium. As the dissociable group, an anionic group is preferable, and a carboxy group and a sulfonic acid group are particularly preferable. For example, the dissociable group is introduced into the polyurethane by using a diol having a dissociable group as a raw material for the polyaddition reaction.

  Examples of the diol having a dissociable group include 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,5,6-trimethoxy-3,4-dihydroxyhexanoic acid. 2,3-dihydroxy-4,5-dimethoxypentanoic acid, 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid, and salts thereof. 1 type may be used for the diol which has a dissociable group, and 2 or more types may be used together.

  Examples of the diol having no dissociable group include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 2,2-dimethyl-1,3-propanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 3,3-dimethyl-1,2, -Butanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl -2,4-pentanediol, 2,2-diethyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 1,7- Butanediol, 2-methyl-2-propyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, , 8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, hydroquinone, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol , Poly (oxytetramethylene) glycol, polyester polyol, 4,4′-dihydroxy-diphenyl-2,2-propane, 4,4′-dihydroxyphenylsulfone, and the like. 1 type may be used for the diol which does not have a dissociable group, and 2 or more types may be used together.

  Examples of the diisocyanate include methylene diisocyanate, ethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene diisocyanate, 1, 5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 3,3′-dimethylbiphenylene diisocyanate, 4,4′-biphenylene diisocyanate, dicyclohexylmethane diisocyanate And methylene bis (4-cyclohexyl isocyanate). 1 type may be used for diisocyanate and it may use 2 or more types together.

-Polyester-
Polyester is generally synthesized by dehydration condensation of a dicarboxylic acid and a diol.

  The polyester preferably has a dissociable group from the viewpoint of dispersibility in an aqueous medium. As the dissociable group, an anionic group is preferable, and a carboxy group and a sulfonic acid group are particularly preferable. The dissociable group is introduced into the polyester by using, for example, a dicarboxylic acid or diol having a sulfonic acid group as a raw material for dehydration condensation.

  Examples of the dicarboxylic acid having a sulfonic acid group include 3-sulfophthalic acid, 4-sulfophthalic acid, 4-sulfoisophthalic acid, 5-sulfoisophthalic acid, 2-sulfoterephthalic acid, sulfosuccinic acid, and 4-sulfo-1,8. -Naphthalenedicarboxylic acid, 7-sulfo-1,5-naphthalenedicarboxylic acid, 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid, and salts thereof. These dicarboxylic acids may be used alone or in combination of two or more.

  Examples of other dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, dimethylmalonic acid, adipic acid, pimelic acid, α, α-dimethylsuccinic acid, acetone dicarboxylic acid, sebacic acid, 1,9- Nonanedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, phthalic acid, isophthalic acid, terephthalic acid, 2-butylterephthalic acid, tetrachloroterephthalic acid, acetylenedicarboxylic acid, poly (ethylene terephthalate) dicarboxylic acid, 1, Examples include 2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, ω-poly (ethylene oxide) dicarboxylic acid, and p-xylylene dicarboxylic acid. These dicarboxylic acids may be subjected to dehydration condensation in the form of alkyl esters, acid chlorides or acid anhydrides. These dicarboxylic acids may be used alone or in combination of two or more.

  Examples of the diol having a sulfonic acid group and other diols include the compounds described above as a raw material for polyurethane. 1 type may be used for diol and it may use 2 or more types together.

-Polyamide-
Polyamide is generally synthesized by polycondensation of diamine and dicarboxylic acid, polycondensation of aminocarboxylic acid, ring-opening polymerization of lactams, or a combination thereof.

  The polyamide preferably has a dissociable group from the viewpoint of dispersibility in an aqueous medium. As the dissociable group, an anionic group is preferable, and a carboxy group and a sulfonic acid group are particularly preferable. The dissociable group is introduced into the polyamide by using, for example, a dicarboxylic acid having a sulfonic acid group as a raw material for polycondensation.

  Examples of the diamine include ethylenediamine, 1,3-propanediamine, 1,2-propanediamine, hexamethylenediamine, octamethylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, piperazine, and 2,5. -Dimethylpiperazine, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, xylylenediamine and the like. 1 type may be used for diamine and it may use 2 or more types together.

  Examples of the dicarboxylic acid having a sulfonic acid group and other dicarboxylic acids include the compounds described above as raw materials for polyester. 1 type may be used for dicarboxylic acid and it may use 2 or more types together.

  Examples of the aminocarboxylic acid include glycine, alanine, phenylalanine, ω-aminohexanoic acid, ω-aminodecanoic acid, ω-aminoundecanoic acid, and anthranilic acid. 1 type may be used for aminocarboxylic acid and it may use 2 or more types together.

  Examples of lactams include ε-caprolactam, azetidinone, pyrrolidone and the like. Lactams may be used alone or in combination of two or more.

-Polyurea-
Polyurea is generally synthesized by a polyaddition reaction between a diamine and a diisocyanate, a deammonification reaction between a diamine and urea, or a combination of these reactions.

  The polyurea preferably has a dissociable group from the viewpoint of dispersibility in an aqueous medium. As the dissociable group, an anionic group is preferable, and a carboxy group and a sulfonic acid group are particularly preferable. For example, the dissociable group is introduced into the polyurea by adding an alcohol or amine having a dissociable group to the isocyanate at the polymer terminal.

  Examples of the diamine include the compounds described above as raw materials for polyamide. 1 type may be used for diamine and it may use 2 or more types together.

  Examples of the diisocyanate include the compounds described above as raw materials for polyurethane. 1 type may be used for diisocyanate and it may use 2 or more types together.

  Examples of the compound for introducing a dissociable group into polyurea include 1-aminocyclohexanecarboxylic acid, 12-aminododecanoic acid, 6-aminohexanoic acid, m-aminobenzenesulfonic acid, and 3-amino-1-propanesulfone. An acid etc. are mentioned. These compounds may be used alone or in combination of two or more.

-Polycarbonate-
Polycarbonates are generally synthesized by reacting diols with phosgene or carbonate derivatives.

  The polycarbonate preferably has a dissociable group from the viewpoint of dispersibility in an aqueous medium. As the dissociable group, an anionic group is preferable, and a carboxy group and a sulfonic acid group are particularly preferable. The dissociable group is introduced into the polycarbonate, for example, by using a diol having a dissociable group as a raw material for polycondensation.

  Examples of the diol having a dissociable group and the diol having no dissociable group include the compounds described above as raw materials for polyurethane. 1 type may be used for diol and it may use 2 or more types together.

  Examples of the carbonate ester derivative include aromatic esters such as diphenyl carbonate. One type of carbonate ester derivative may be used, or two or more types may be used in combination.

  The polymer is synthesized by selecting a monomer type from the viewpoint of controlling the acid value, glass transition temperature, solubility in an organic solvent, affinity for a specific infrared absorber, and the like.

  Hereinafter, specific examples of the polymer will be exemplified by describing the polymerization components. However, for polymers produced by condensation reactions such as polyesters and polyamides, dicarboxylic acids, diols, diamines, hydroxycarboxylic acids, aminocarboxylic acids, etc., which are constituent units of the polymers, are described regardless of the polymerization components. The parenthesis is the molar ratio of the polymerization components. The present invention is not limited to these specific examples.

-Polyurethane-
Toluene diisocyanate / ethylene glycol / 1,4-butanediol (50/15/35)
・ 4,4′-diphenylmethane diisocyanate / 1,3-propanediol / polypropylene glycol (Mw1000) (50/45/5)
Toluene diisocyanate / hexamethylene diisocyanate / ethylene glycol / polyethylene glycol (Mw 600) / 1,4-butanediol (40/10/20/10/20)
1,5-naphthylene diisocyanate / hexamethylene diisocyanate / diethylene glycol / 1,6-hexanediol (25/25/35/15)
・ 4,4′-diphenylmethane diisocyanate / hexamethylene diisocyanate / tetraethylene glycol / ethylene glycol / 2,2-bis (hydroxymethyl) propionic acid (40/10/20/20/10)
4,4'-diphenylmethane diisocyanate / hexamethylene diisocyanate / butanediol / ethylene glycol / 2,2-bis (hydroxymethyl) propionic acid (40/10/20/20/10)
1,5-naphthylene diisocyanate / butanediol / 2,2′-bis (4-hydroxyphenyl) propane / polypropylene glycol (Mw 400) / 2,2-bis (hydroxymethyl) propionic acid (50/20/5 / (10/15)
1,5-naphthylene diisocyanate / hexamethylene diisocyanate / 2,2-bis (hydroxymethyl) butanoic acid / polybutylene oxide (Mw 500) (35/15/25/25)
Isophorone diisocyanate / diethylene glycol / neopentyl glycol / 2,2-bis (hydroxymethyl) propionic acid (50/20/20/10)
Toluene diisocyanate / 2,2-bis (hydroxymethyl) butanoic acid / polyethylene glycol (Mw1000) / cyclohexanedimethanol (50/10/10/30)
Diphenylmethane diisocyanate / hexamethylene diisocyanate / tetraethylene glycol / butanediol / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (40/10/10/33/7)
Diphenylmethane diisocyanate / hexamethylene diisocyanate / butanediol / ethylene glycol / 2,2-bis (hydroxymethyl) butanoic acid / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (40/10/20/15 / 10/5)
Isophorone diisocyanate / poly (oxytetramethylene) glycol (Mn2000) / neopentylglycol / 2,2-bis (hydroxymethyl) propionic acid (50 / 9.5 / 6.2 / 34.3)
Isophorone diisocyanate / polypropylene glycol (Mn1000) / neopentyl glycol / 2,2-bis (hydroxymethyl) propionic acid (50/20/15/15)
Isophorone diisocyanate / poly (oxytetramethylene) glycol (Mn2000) / triethylene glycol / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (50/20/18/12)

-Polyester-
・ Terephthalic acid / isophthalic acid / cyclohexanedimethanol / 1,4-butanediol / ethylene glycol (25/25/25/15/10)
・ Terephthalic acid / isophthalic acid / 2,2′-bis (4-hydroxyphenyl) propane / tetraethylene glycol / ethylene glycol (30/20/20/15/15)
・ Terephthalic acid / isophthalic acid / cyclohexanedimethanol / neopentyl glycol / diethylene glycol (20/30/25/15/10)
・ Terephthalic acid / isophthalic acid / 4,4′-benzenedimethanol / diethylene glycol / neopentyl glycol (25/25/25/15/10)
・ Terephthalic acid / isophthalic acid / 5-sulfoisophthalic acid / ethylene glycol / neopentyl glycol (24/24/2/25/25)
・ Terephthalic acid / isophthalic acid / 5-sulfoisophthalic acid / cyclohexanedimethanol / 1,4-butanediol / ethylene glycol (22/22/6/25/15/10)
・ Isophthalic acid / 5-sulfoisophthalic acid / cyclohexanedimethanol / ethylene glycol (40/10/40/10)
・ Cyclohexanedicarboxylic acid / isophthalic acid / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid / cyclohexanedimethanol / ethylene glycol (30/20/5/25/20)

-Polyamide-
11-aminoundecanoic acid (100)
12-aminododecanoic acid (100)
Product of reaction of poly (12-aminododecanoic acid) with maleic anhydride 11-aminoundecanoic acid / 7-aminoheptanoic acid (50/50)
・ Hexamethylenediamine / Adipic acid (50/50)
・ Tetramethylenediamine / Adipic acid (50/50)
・ Hexamethylenediamine / Sebacic acid (50/50)
・ N, N-dimethylethylenediamine / adipic acid / cyclohexanedicarboxylic acid (50/20/30)

-Polyurea-
Toluene diisocyanate / hexamethylenediamine / 2,2-bis (hydroxymethyl) propionic acid (50/40/10)
11-aminoundecanoic acid / hexamethylenediamine / urea (33/33/33)

-Polycarbonate-
・ One-terminal phthalic anhydride adduct of 1,6-hexanediol polycarbonate diol (Mw2000) ・ One-end anhydrous of 1,6-hexanediol / 1,4-butanediol (molar ratio 1: 1) polycarbonate diol (Mw2000) Phthalic acid adduct, one-terminal phthalic anhydride adduct of 1,6-hexanediol / 1,5-heptanediol (molar ratio 1: 1) polycarbonate diol (Mw2000)

The molecular weight range of the polymer is preferably 1000 to 200,000 as a weight average molecular weight. When the weight average molecular weight is 1000 or more, the content ratio of the water-soluble component is reduced, which is suitable for the dispersion of the specific infrared absorber. 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. Dispersion of the specific particles becomes easy, and thus the dispersion stability of the specific particles is excellent. From the above viewpoint, the molecular weight range of the polymer is more preferably 5,000 to 100,000, further preferably 10,000 to 50,000.
The weight average molecular weight of the polymer is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

  The glass transition temperature of the polymer is preferably 40 to 150 ° C. When the glass transition temperature is 40 ° C. or higher, the image formed using the polymer-containing ink has excellent scratch resistance and blocking resistance, and when the glass transition temperature is 150 ° C. or lower, the polymer-containing ink is used. Excellent in abrasion resistance of the formed image. From this viewpoint, the glass transition temperature of the polymer is more preferably 60 to 140 ° C, and further preferably 70 to 130 ° C.

[First water-soluble organic solvent, second water-soluble organic solvent]
Examples of the water-soluble organic solvent contained in the particle dispersion and the water-based ink according to this embodiment include alcohols, polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, and sulfur-containing solvents.

In this embodiment, the SP value (solubility parameter) of the water-soluble organic solvent is an SP value calculated by the Okitsu method, and the unit is (J / cm ³ ) ^1/2 .

  Examples of the first water-soluble organic solvent having an SP value of 24 or more and less than 27 include propylene glycol (SP value 26.7), 1,3-propanediol (SP value 26.7), diethylene glycol (SP value 26). .1) and the like.

  Examples of the second water-soluble organic solvent having an SP value of 27 or more and 32 or less include ethylene glycol (SP value 29.7), 2-pyrrolidone (SP value 29.1), diglycerol (SP value 32), and the like. Is mentioned. As the second water-soluble organic solvent, ethylene glycol or 2-pyrrolidone is preferable from the viewpoint of easy drying of the water-based ink on the recording medium.

  The total of the first water-soluble organic solvent and the second water-soluble organic solvent is preferably 18 to 36% by mass of the entire aqueous ink. When the total of both is 18% by mass or more, the redispersibility of the concentrated specific particles is excellent. On the other hand, when the total of both is 36% by mass or less, the dispersibility of the specific infrared absorber is more stable and the infrared rays are reduced. Excellent absorption performance. From the above viewpoint, the total of both is more preferably 20 to 35% by mass, more preferably 22 to 32% by mass, and still more preferably 25 to 30% by mass.

  The second water-soluble organic solvent is preferably 2 to 16% by mass of the entire aqueous ink. When the second water-soluble organic solvent is 2% by mass or more, it is excellent in the redispersibility of the concentrated specific particles. On the other hand, when the second water-soluble organic solvent is 16% by mass or less, the specific infrared absorber Dispersibility is more stable and excellent in infrared absorption performance. From the above viewpoint, the second water-soluble organic solvent is more preferably 2 to 15% by mass or less, and further preferably 3 to 11% by mass or less.

  The particle dispersion and the water-based ink according to this embodiment may contain a water-soluble organic solvent having an SP value of less than 24 and a water-soluble organic solvent having an SP value of more than 32. The total amount of organic solvents is preferably 1% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0% by mass with respect to the entire aqueous ink.

[Colorant]
The aqueous ink according to this embodiment may contain a 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 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 polymer 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 to 200 nm.

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

[Additive]
The particle dispersion and aqueous ink according to the present embodiment may contain various additives as necessary. Examples of additives include polymers, surfactants, dispersion stabilizers, penetrants, viscosity modifiers, neutralizers, pH adjusters, pH buffers, antioxidants, ultraviolet absorbers, antiseptics, and antifungal agents. Can be mentioned. The particle dispersion and the water-based ink according to this embodiment may contain a compound having infrared absorbing ability other than the specific infrared absorber.

[Physical properties of particle dispersion and aqueous ink]
The volume average particle size of the specific particles contained in the particle dispersion and the aqueous ink is preferably 10 to 150 nm. When the volume average particle size of the specific particles is 10 nm or more, the light resistance is excellent, and when the specific particles are 150 nm or less, the droplet ejection characteristics of the inkjet method are excellent. From the above viewpoint, the volume average particle size of the specific particles is more preferably 10 to 120 nm, and still more preferably 10 to 100 nm. The average particle size and particle size distribution of the specific particles are measured using, for example, a light scattering method.

  The pH of the particle dispersion and aqueous ink according to this embodiment is preferably 6.5 to 11.0, more preferably 7.0 to 10.5, and even more preferably 8.0 to 10.0. In this embodiment, the pH of the particle dispersion and the aqueous 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 particle dispersion and the aqueous ink according to this embodiment is preferably 20 to 40 mN / m, and more preferably 25 to 35 mN / m. In this embodiment, the surface tension of the particle dispersion and aqueous 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 particle dispersion and the aqueous ink according to this embodiment is preferably 1 to 30 mPa · s, and more preferably 2 to 20 mPa · s. In this embodiment, the viscosity of the particle dispersion and 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.

[Production method of particle dispersion and aqueous ink]
The particle dispersion according to this embodiment is prepared, for example, by preparing a dispersion in which specific particles are dispersed, and mixing the dispersion, the first water-soluble organic solvent, and the second water-soluble organic solvent. Manufactured.

  The water-based ink according to the present embodiment is produced, for example, by adding a colorant to the particle dispersion according to the present embodiment. The water-based ink according to this embodiment may be the particle dispersion itself according to this embodiment.

  Examples of the method for preparing a dispersion in which specific particles are dispersed include a phase inversion emulsification method and an impregnation method, and the phase inversion emulsification method is preferable.

  The phase inversion emulsification method prepares a solution in which a specific infrared absorber and a polymer are dissolved in an organic solvent, neutralizes the polymer by adding a neutralizing agent to the solution, and then gradually mixes water with the specific infrared absorber. This is a method of making particles dispersed into particles containing both a polymer and a polymer. 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 used in the phase inversion emulsification method has an SP value of less than 24 or more than 32, a solubility of the organic solvent in water of 10% by mass or less, or a vapor of the organic solvent. When the pressure is higher than water, it is preferably removed from the viewpoint of the dispersion stability of the specific particles. Neutralization is not an essential step, but when the polymer has an unneutralized dissociable group, it is preferably performed from the viewpoint of pH adjustment of the dispersion.

  The impregnation method involves preparing a polymer particle dispersion, mixing the polymer particle dispersion and a solution in which a specific infrared absorber is dissolved in an organic solvent, and then gradually removing the organic solvent to remove the specific infrared absorber from the polymer particles. And impregnated into specific particles. The polymer particles may be liquid particles or solid particles, and solid particles are preferable from the viewpoint of dispersion stability. The polymer particle dispersion is prepared, for example, by preparing a solution in which the polymer is dissolved, neutralizing the solution by adding a neutralizing agent, and then removing the organic solvent while gradually mixing water.

  The organic solvent used for the phase inversion emulsification method and the impregnation method is selected based on the solubility of the specific infrared absorber and the solubility of the polymer. 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 the organic solvent used for the phase inversion emulsification method and the impregnation method, 10-2000 mass parts is preferable with respect to 100 mass parts of polymers, and 100-1000 mass parts is 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 polymer, 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 polymer, The process of removing is unnecessary or can be completed in a short time.

  As the neutralizing agent used in the phase inversion emulsification method and the impregnation method, when the polymer has an anionic group, an organic base or an inorganic alkali is preferable. 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 an addition amount that makes the pH of the particle dispersion in the above-mentioned range from the viewpoint of the dispersion stability of the specific particles.

  The amount of the polymer used in the phase inversion emulsification method and the impregnation method and the content of the polymer contained in the particle dispersion are preferably 100 to 9900 parts by weight, and 300 to 4900, with respect to 100 parts by weight of the compound having infrared absorbing ability. Part by mass is more preferable. When the amount of the polymer used (polymer content) 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 polymer used (polymer containing) When the amount is 9900 parts by mass or less with respect to 100 parts by mass of the compound having infrared absorbing ability, the infrared absorption efficiency of the particle dispersion is good.

  In the phase inversion emulsification method and the impregnation method, an organic compound other than the specific infrared absorber may be used, and the compound may be granulated with the specific infrared absorber and the polymer to form particles containing the three. Examples of the organic compound that forms particles together include, for example, compounds having infrared absorbing ability other than dyes and specific infrared absorbers (for example, squarylium dyes, croconium dyes, naphthalocyanine dyes, cyanine dyes, aminium dyes, etc.) And compounds having ultraviolet absorbing ability (for example, benzotriazole compounds, benzophenone compounds, etc.).

<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 unit, in addition to the infrared irradiation unit, a contact heating unit such as a heating roll, a heating drum, and a heating belt; a hot air blowing unit including a heating element and a blower; a combination thereof 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 ink droplet amounts of 10 to 15 pL. This is a recording head for 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, the center wavelength is 700 to 1200 nm (preferably 780 to 980 nm), the irradiation intensity is 0.1 to 10 J / cm ² (preferably 1 to 3 J / cm ² ), and the irradiation time is 0.1 mm. Second to 10 seconds (preferably 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 heating unit and a hot air blowing unit as an ink drying unit together with the infrared irradiation device 60. The contact-type heating unit or the hot air blowing unit performs drying under conditions that raise the surface temperature of the recording medium to a range of 50 to 120 ° C., 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.

  Hereinafter, embodiments of the present invention will be described in detail by way of examples, but the embodiments of the present invention are not limited to these examples. In the following description, all “parts” are based on mass unless otherwise specified.

[Synthesis of Compound (Ia-1)]
Compound (Ia-1) was synthesized as a compound represented by general formula (Ia) 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 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 internal temperature rose by heat_generation | fever, it dripped in the range of 5-7 degreeC inside temperature, adjusting dripping 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 (Id-2)]
The starting material in the synthesis of compound (Ia-1) was changed (a compound having two t-butyl groups was changed to a compound having one t-butyl group and one nC ₅ H ₁₁ group). Compound (Id-2) was synthesized in the same procedure except for the above.

[Synthesis of Compound (II-b-1)]
Compound (II-b-1) was synthesized according to the synthesis method described in JP 2010-186014 A.

[Synthesis of polymer (1)]
・ Dimethyl terephthalate 90.1 parts ・ Dimethyl isophthalate 90.1 parts ・ Methyl fumarate 21.0 parts ・ Bisphenol A ethylene oxide 2 mol adduct 146.2 parts ・ Bisphenol A propylene oxide 2 mol adduct 162.2 parts ・Ethylene glycol 22.0 parts A three-necked flask equipped with a stirrer and a distillation tube is charged with the above raw material monomer, 0.1 part of calcium acetate and 0.1 part of antimony (III) oxide as a condensation catalyst, under a nitrogen stream. The mixture was heated while distilling off the methanol and ethylene glycol produced, stirred for 30 minutes while maintaining at 150 ° C., and further stirred for 1 hour while maintaining at 200 ° C. Next, the temperature is lowered to 150 ° C., the pressure in the reaction system is gradually reduced by a pump with stirring, and the reaction system is raised while distilling off ethylene glycol while maintaining the pressure in the reaction system in the range of 10 to 40 Pa. Warm and react at 240 ° C. for an additional 3 hours. The product was taken out and cooled to obtain a polymer (1) which was a polyester. The polymer (1) had a weight average molecular weight (Mw) of 16,000 and an acid value of 16 mgKOH / g.

[Synthesis of polymer (2)]
-Toluene diisocyanate 75 parts-Ethylene glycol 22.5 parts-1,4-butanediol 52.5 parts The polymer (2) which is a polyurethane was synthesize | combined from the said raw material monomer by the usual method. The polymer (2) had a weight average molecular weight (Mw) of 22,000 and an acid value of 20 mgKOH / g.

[Synthesis of polymer (3)]
-Hexamethylenediamine 80 parts-Adipic acid 80 parts The polymer (3) which is a polyamide was synthesize | combined by the usual method from said raw material monomer. The polymer (3) had a weight average molecular weight (Mw) of 14,000 and an acid value of 8 mgKOH / g.

[Synthesis of polymer (4)]
-Toluene diisocyanate 100 parts-Hexamethylenediamine 80 parts-2,2-bis (hydroxymethyl) propionic acid 20 parts The polymer (4) which is a polyurea was synthesize | combined from the said raw material monomer by the usual method. The polymer (4) had a weight average molecular weight (Mw) of 9,000 and an acid value of 8 mgKOH / g.

[Synthesis of polymer (5)]
-1,6-hexanediol 118 parts-1,4-butanediol polycarbonate diol (Mw2000) one-terminal phthalic anhydride adduct 100 parts A polymer (5), which is a polycarbonate, was synthesized from the above raw material monomers by a conventional method. The polymer (5) had a weight average molecular weight (Mw) of 8,000 and an acid value of 16 mgKOH / g.

<Example 1>
[Production of Particle (1)]
0.3 parts of compound (Ia-1) was put into a flask. Thereto was added 14 parts of tetrahydrofuran, and a stir bar was added and stirred. Next, 10 parts of the polymer (1) was added, and further 30 parts of methyl ethyl ketone was added and stirred and mixed. Next, an 8% aqueous solution of sodium hydroxide was added with stirring, 0.9 equivalent of all carboxy groups contained in the polymer (1) (degree of neutralization 90%). Next, 120 parts of water was gradually added while stirring, and mixed with water. Thereafter, a distillation tube and a vacuum pump were attached to the flask, and the mixed solution was heated to 42 to 52 ° C. and depressurized while stirring to distill off the organic solvent. It was repeated until the organic solvent odor disappeared while adjusting the amount of water added so that the solid content concentration did not exceed 11% by mass. The concentrate was filtered through a 230 mesh nylon mesh to obtain a particle dispersion. The solid content of the particle dispersion was measured, and water was added based on the measured solid content to adjust the solid content to 10% by mass, thereby preparing a dispersion of particles (1). When converted from the amount of the compound (Ia-1) and the amount of the polymer (1), the concentration of the compound (Ia-1) in the dispersion of the particles (1) was 0.32% by mass.

[Production of polymer-coated cyan pigment (1)]
In a reaction vessel, 6 parts of styrene, 11 parts of stearyl methacrylate, 4 parts of styrene macromer AS-6 (manufactured by Toa Gosei), 5 parts of Blenmer PP-500 (manufactured by NOF), 5 parts of methacrylic acid, 0.05 of 2-mercaptoethanol A mixed solution consisting of 24 parts of methyl ethyl ketone was prepared. Separately, 14 parts of styrene, 24 parts of stearyl methacrylate, 9 parts of styrene macromer AS-6 (Toagosei), 9 parts of Bremer PP-500 (Nippon Oil), 10 parts of methacrylic acid, 0.13 part of 2-mercaptoethanol, 56 of methyl ethyl ketone And a mixed solution consisting of 1.2 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) was prepared and placed in a dropping funnel.
While stirring the mixed solution in the reaction vessel under a nitrogen atmosphere, the temperature was raised to 75 ° C., and the mixed solution in the dropping funnel was dropped over 1 hour. 2 hours after the completion of the dropwise addition, a solution prepared by dissolving 1.2 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) in 12 parts of methyl ethyl ketone was added dropwise over 3 hours and reacted at 75 ° C. for 2 hours. Further, the mixture was aged at 80 ° C. for 2 hours to obtain a polymer solution.
5 parts of polymer solution obtained (in terms of solid content), 10 parts of Pigment Blue 15: 3 (Daiichi Seika Kogyo), 40 parts of methyl ethyl ketone, 8 parts of 1 mol / L aqueous sodium hydroxide solution and 82 parts of ion-exchanged water The mixture was charged into a bead mill disperser together with 300 parts of 1 mm zirconia beads and dispersed for 6 hours. The obtained dispersion was concentrated under reduced pressure using an evaporator to remove methyl ethyl ketone and to concentrate to a pigment concentration of 10% by mass. Thus, a dispersion liquid in which the polymer-coated cyan pigment (1) was dispersed was obtained. The volume average particle diameter of the polymer-coated cyan pigment (1) contained in the dispersion was 77 nm.

[Manufacture of cyan ink (1)]
After the following materials were mixed, coarse particles were removed with a 5 μm filter to obtain cyan ink (1). The pH of the cyan ink (1) was 6.

・ Particulate dispersion of particles (1) 3 parts ・ Dispersion of polymer-coated cyan pigment (1) 9 parts ・ Propylene glycol 20 parts ・ Ethylene glycol 10 parts ・ Orphine E1010 (Nisshin Chemical Industry) 0.5 part ・ Ion-exchanged water 57.5 parts

<Examples 2-55 and Comparative Examples 1-2>
Except that the type of specific infrared absorber, the type of polymer, the type and content of the water-soluble organic solvent were changed as shown in Tables 3 to 5, the same procedure as in Example 1 was followed. ) To (57) were produced.

<Performance evaluation of water-based ink>
For the cyan inks (1) to (57) of each Example and Comparative Example, performance evaluation was performed as follows. Tables 3 to 5 show the results.

[Concentrated redispersibility]
The cyan ink of each example was placed in a glass petri dish, heated at 40 ° C., and concentrated to 40% by mass. Thereafter, in an environment at a temperature of 23 ° C., ion-exchanged water (temperature: 23 ° C.) was added and diluted so as to obtain the original ink amount, and the state of this diluted solution was visually observed and classified as follows. . Acceptable are AD.

A: A solid substance cannot be confirmed on the petri dish. Aggregates in the diluted solution cannot be confirmed.
B: Although a solid substance can be confirmed slightly on the petri dish, aggregates in the diluted solution cannot be confirmed.
C: Solids can be confirmed on the petri dish, and agglomerates can be slightly confirmed in the diluted solution.
D: Solids can be confirmed on the petri dish, and aggregates can be confirmed in the diluted solution, but this is within the allowable range.
E: A solid substance can be confirmed on the petri dish, and an aggregate is present in an unacceptable range in the diluted solution.

[Infrared absorption performance]
The cyan ink of each example was diluted 600 times, and the infrared absorption at a wavelength of 818 nm was measured using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd., cell: optical path length 1.00 cm). From the obtained absorption intensity, the absorption intensity corrected to the solid content concentration of 5.0% by mass was calculated based on the dilution ratio and the original solid content concentration. The above measurement was performed immediately after ink preparation and after storage for 2 weeks in a 60 ° C. environment, and the ratio of the latter absorption intensity to the former absorption intensity was classified as follows. Acceptable are AE.

A: 95% or more B: 90% or more, less than 95% C: 85% or more, less than 90% D: 80% or more, less than 85% E: 75% or more, less than 80% F: less than 75%

[Drying on recording media]
The cyan ink in each example was refilled into a cartridge of an Epson ink jet printer PX-1004, and the ink jet printer PX-1004 was applied to Tokishi Art Duplex N (Mitsubishi Paper) in an environment of 23 ° C./55% relative humidity. Printed. After printing, leave it in the same environment for 10 minutes, fold the paper so that the image is inside, rub the crease and its periphery with your fingers, spread the folded paper, and visually observe the degree of image loss caused by rubbing And classified as follows.

A: Image defect cannot be confirmed.
B: The image was slightly lost.
C: Image defect was confirmed.

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 (17)

water and,
Particles containing at least one compound selected from a compound represented by the following general formula (I) and a compound represented by the following general formula (II) and a polymer;
A first water-soluble organic solvent having an SP value calculated by the Okitsu method of 24 or more and less than 27;
A second water-soluble organic solvent having an SP value of 27 or more and 32 or less calculated by the Okitsu method;
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, and R ^2a and R ^2b and R ^2c and R ^2d are each independently connected to form a ring. May be. The particle dispersion liquid according to claim 1, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (Ia).

In general formula (Ia), R ^a represents a group represented by general formula (Ib), and R ^b , R ^c, and R ^d each independently represents an alkyl group. In the general formula (I-b), ^{R e} represents hydrogen or a methyl group, n represents an integer of 0 to 3.   The particle dispersion according to claim 1 or 2, wherein the second water-soluble organic solvent contains at least one of ethylene glycol and 2-pyrrolidone.  The particle dispersion according to any one of claims 1 to 3, wherein the polymer contains at least one selected from polyurethane, polyester, polyamide, polyurea and polycarbonate. water and,
Particles containing at least one compound selected from a compound represented by the following general formula (I) and a compound represented by the following general formula (II) and a polymer;
A first water-soluble organic solvent having an SP value calculated by the Okitsu method of 24 or more and less than 27;
A second water-soluble organic solvent having an SP value of 27 or more and 32 or less calculated by the Okitsu method;
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, and R ^2a and R ^2b and R ^2c and R ^2d are each independently connected to form a ring. May be. The water-based ink according to claim 5, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (Ia).

In general formula (Ia), R ^a represents a group represented by general formula (Ib), and R ^b , R ^c, and R ^d each independently represents an alkyl group. In the general formula (I-b), ^{R e} represents hydrogen or a methyl group, n represents an integer of 0 to 3.   The water-based ink according to claim 5 or 6, wherein the second water-soluble organic solvent contains at least one of ethylene glycol and 2-pyrrolidone.  The water-based ink according to any one of claims 5 to 7, wherein the polymer contains at least one selected from polyurethane, polyester, polyamide, polyurea and polycarbonate.   The aqueous solution according to any one of claims 5 to 8, wherein a total of the first water-soluble organic solvent and the second water-soluble organic solvent is 18 to 36% by mass of the entire aqueous ink. ink.   The aqueous solution according to any one of claims 5 to 9, wherein the total of the first water-soluble organic solvent and the second water-soluble organic solvent is 20 to 35 mass% of the entire aqueous ink. ink.   The aqueous ink according to any one of claims 5 to 10, wherein the second water-soluble organic solvent is 2 to 16% by mass of the entire aqueous ink.   The water-based ink according to any one of claims 5 to 11, wherein the second water-soluble organic solvent is 3 to 11% by mass of the entire water-based ink.   An ink cartridge containing the water-based ink according to any one of claims 5 to 12. An ink application unit that contains the water-based ink according to any one of claims 5 to 12 and that applies the water-based ink to a recording medium;
Infrared irradiation means for irradiating the water-based ink applied to the recording medium with infrared rays;
A recording apparatus comprising:   The recording apparatus according to claim 14, wherein the ink applying unit includes an ink jet head that discharges the water-based ink, and is a unit that discharges the water-based ink from the ink-jet head and applies the water-based ink to a recording medium. An ink application step for applying the water-based ink according to any one of claims 5 to 12 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.   The recording method according to claim 16, wherein the ink applying step is a step of discharging the water-based ink from an ink jet head and applying the ink to a recording medium.