JP6900467B2 - Inkjet ink, its manufacturing method, and image forming method - Google Patents

Description

The present disclosure relates to an inkjet ink, a method for producing the ink jet ink, and a method for forming an image.

Inkjet inks containing polymers such as polyurethane and polyurea and water are known.
For example, aqueous UV inkjet inks are disclosed that include at least one photopolymerization initiator and a capsule composed of a shell made of a crosslinked polymer that surrounds the core, wherein the core contains a UV curable compound (eg,). See International Publication No. 2015/158748). Paragraph 1981 of WO 2015/158748 states that the shell is preferably made of polyurethane, polyurea, or a combination thereof.

However, there are cases where it is required to further improve the ejection property from the inkjet head in an inkjet ink containing particles (capsules or the like) containing a polymer, such as the inkjet ink described in International Publication No. 2015/158748. is there.
Therefore, an object of the present disclosure is to provide an inkjet ink having excellent ejection properties from an inkjet head, a method for producing the same, and an image forming method using the inkjet ink.

Specific means for solving the above problems include the following aspects.
<1> With water
Particles containing a polymer having at least one of a urethane bond and a urea bond,
At least one bond selected from the group consisting of urethane bond, urea bond, thiourethane bond, and thiourea bond, and hydrophilicity which is at least one selected from the group consisting of anionic group and nonionic group. Hydrophilic group-containing compounds having groups, having a number average molecular weight of 1000 or more, and having a content of 0.01% by mass to 1% by mass with respect to the total amount of the inkjet ink.
Inkjet ink containing.

<2> The hydrophilic group-containing compound is
Reaction product X1, of a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, and a bifunctional isocyanate compound,
Reaction product X2 of a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups.
Reaction product X3 of trifunctional or higher functional isocyanate compound, compound having hydrophilic group and active hydrogen group which is an anionic group or nonionic group, and water, or
Reaction product of a compound having 3 or more active hydrogen groups, a bifunctional isocyanate compound, a hydrophilic group which is an anionic group or a nonionic group, and a compound having an active hydrogen group PX, and a reaction product of water. X4
The inkjet ink according to <1>.

<3> The inkjet ink according to <1> or <2>, wherein the hydrophilic group-containing compound contains the following structural unit (X).

In the structural unit (X),
U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond,
R represents a divalent hydrocarbon group having 1 to 20 carbon atoms.
X ¹ represents a (n + m) -valued linking group.
W represents a hydrophilic group which is an anionic group or a nonionic group.
n represents 0 or 1 and represents
m represents an integer of 2 to 6 and represents
(N + m) is an integer of 3 to 6 and
* Indicates the bond position with the group (UW), the bond position with the primary amino group, or the bond position with other structural units via urethane bond, urea bond, thiourethane bond, or thiourea bond. ..
In the base (UW),
U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond,
W represents a hydrophilic group which is an anionic group or a nonionic group.
L represents a single bond or a divalent linking group.
* Represents the connection position with the structural unit (X).

<4> The hydrophilic group contained in the hydrophilic group-containing compound is at least one of a carboxy group and a salt of the carboxy group, or is a monovalent group containing a polyoxyalkylene chain <1> to <3>. The inkjet ink according to any one of the above.
<5> Described in any one of <1> to <4>, wherein the polymer contained in the particles further has a hydrophilic group which is at least one selected from the group consisting of an anionic group and a nonionic group. Inkjet ink.
<6> The inkjet ink according to <5>, wherein at least one hydrophilic group contained in the polymer contained in the particles and at least one hydrophilic group contained in the hydrophilic group-containing compound are the same type of group.
<7> The polymer and hydrophilic group-containing compound contained in the particles are
It has a structure derived from the same type of bifunctional isocyanate compound and has a structure.
The inkjet ink according to any one of <1> to <6>, which has a structure derived from the same type of compound having a hydrophilic group which is an anionic group or a nonionic group and an active hydrogen group.
<8> The inkjet ink according to any one of <1> to <7>, wherein the number average molecular weight of the hydrophilic group-containing compound is 2000 to 50000.
<9> The inkjet ink according to any one of <1> to <8>, wherein the particles have a polymerizable group.

<10> The method for producing an inkjet ink according to any one of <1> to <9>.
Hydrophilic group-containing compounds
Reaction product X1, of a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, and a bifunctional isocyanate compound,
Reaction product X2 of a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups.
Reaction product X3 of trifunctional or higher functional isocyanate compound, compound having hydrophilic group and active hydrogen group which is an anionic group or nonionic group, and water, or
Reaction product of a compound having 3 or more active hydrogen groups, a bifunctional isocyanate compound, a hydrophilic group which is an anionic group or a nonionic group, and a compound having an active hydrogen group PX, and a reaction product of water. X4,
A step of forming particles by mixing and emulsifying an oil phase component containing an organic solvent and a polymer, or an oil phase component containing an organic solvent and a trifunctional or higher functional isocyanate compound, and an aqueous phase component containing water. Have,
When the hydrophilic group-containing compound is the reaction product X1 or the reaction product X2, the oil phase component contains the hydrophilic group-containing compound, and the hydrophilic group-containing compound is contained.
A method for producing an inkjet ink in which the aqueous phase component contains the hydrophilic group-containing compound when the hydrophilic group-containing compound is the reaction product X3 or the reaction product X4.

<11> An image forming method including a step of applying the inkjet ink according to any one of <1> to <9> onto a substrate.

According to the present disclosure, an inkjet ink having excellent ejection properties from an inkjet head, a method for producing the same, and an image forming method using the inkjet ink are provided.

In the present specification, the numerical range indicated by using "~" means a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively.
In the present specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means.
In the present specification, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. Is done.
In the present specification, "*" in the chemical formula represents a binding position.

As used herein, the term "image" means the entire film formed by the ink. The concept of "image" includes not only pattern images (eg, characters, symbols, or graphics) but also solid images.
In the present specification, "light" is a concept including active energy rays such as γ-rays, β-rays, electron beams, ultraviolet rays, and visible rays.
In the present specification, ultraviolet rays are sometimes referred to as "UV (Ultra Violet) light".
In the present specification, the light generated from an LED (Light Emitting Diode) light source may be referred to as "LED light".
In the present specification, "(meth) acrylic acid" is a concept including both acrylic acid and methacrylic acid, and "(meth) acrylate" is a concept including both acrylate and methacrylate, and "( "Meta) acryloyl group" is a concept that includes both an acryloyl group and a methacryloyl group.

[Inkjet ink]
The inkjet ink of the present disclosure (hereinafter, also simply referred to as “ink”) contains particles (hereinafter, “specific particles”) containing water and a polymer having at least one of urethane bond and urea bond (hereinafter, also referred to as “specific polymer”). , And at least one bond selected from the group consisting of urethane bond, urea bond, thiourethane bond, and thiourea bond, and at least selected from the group consisting of anionic group and nonionic group. A hydrophilic group-containing compound having one kind of hydrophilic group, having a number average molecular weight of 1000 or more, and having a content of 0.01% by mass to 1% by mass based on the total amount of the inkjet ink (hereinafter, "specific hydrophilicity"). Also referred to as "group-containing compound").

The ink of the present disclosure is excellent in ejection property from an inkjet head (hereinafter, also simply referred to as “ejection property”).
The presumed reason for this effect to be achieved is as follows. However, the ink of the present disclosure is not limited by the following presumed reasons.

In the inks of the present disclosure, the specific particles include a specific polymer having at least one of a urethane bond and a urea bond (hereinafter, also referred to as "urethane bond and / or urea bond").
On the other hand, in the ink of the present disclosure, the specific hydrophilic group-containing compound is at least one bond selected from the group consisting of urethane bond, urea bond, thiourethane bond, and thiourea bond (hereinafter, also referred to as "bond U"). To be referred to).
In the ink of the present disclosure, an interaction (for example, an interaction by a hydrogen bond) between a urethane bond and / or a urea bond contained in a polymer in a specific particle and a bond U contained in a specific hydrophilic group-containing compound). As a result, it is considered that an interaction occurs between the specific polymer and the specific hydrophilic group-containing compound.
In the ink of the present disclosure, the interaction between the specific polymer and the specific hydrophilic group-containing compound and the dispersion action of the specific hydrophilic group-containing compound due to the hydrophilic group are combined to improve the dispersion stability of the specific particles. It is considered that the improvement is achieved, and as a result, the ejection property of the ink is improved.
The above-mentioned effect of the specific hydrophilic group-containing compound (improvement of dispersion stability of specific particles and the effect of improving ink ejection property) is that the content of the specific hydrophilic group-containing compound in the ink is 0.01 mass by mass. It is demonstrated by being% or more.

On the other hand, it was found that when the content of the specific hydrophilic group-containing compound exceeds 1% by mass, the ejection property is lowered. It is considered that the reason for this is that when the content of the specific hydrophilic group-containing compound exceeds 1% by mass, the ink gels due to the aggregation of the specific hydrophilic group-containing compounds.
In this regard, in the ink of the present disclosure, the content of the specific hydrophilic group-containing compound in the ink is 1% by mass or less. As a result, it is considered that the deterioration of the ink ejection property due to the gelation of the ink is suppressed, and as a result, the ink ejection property is improved.

The ink of the present disclosure is also excellent in ink ejection property after storage (hereinafter, also simply referred to as “storage stability”). As the reason for the excellent storage stability, the same reason as the reason for the excellent discharge property can be considered.

Hereinafter, each component that can be contained in the ink of the present disclosure will be described.

<Specific hydrophilic group-containing compound>
The ink of the present disclosure contains at least one specific hydrophilic group-containing compound.
The specific hydrophilic group-containing compound is composed of a bond U (that is, at least one bond selected from the group consisting of a urethane bond, a urea bond, a thiourethane bond, and a thiourea bond), and an anionic group and a nonionic group. It has at least one hydrophilic group selected from the above group and has a number average molecular weight of 1000 or more.

The number average molecular weight of the specific hydrophilic group-containing compound is 1000 or more. As a result, the dispersion stability of the specific particles is improved, and thereby the ink ejection property is improved.

On the other hand, from the viewpoint of further suppressing the gelation of the ink and further suppressing the decrease in ejection property due to the gelation of the ink, the number average molecular weight of the specific hydrophilic group-containing compound is preferably 100,000 or less, preferably 50,000 or less. Is more preferable.
Further, from the viewpoint of further improving the storage stability of the ink, the number average molecular weight of the specific hydrophilic group-containing compound is preferably 2000 or more.
From the above viewpoint, the number average molecular weight of the specific hydrophilic group-containing compound is preferably 1000 to 100,000, more preferably 2000 to 50,000.

In the present specification, the number average molecular weight (Mn) and the weight average molecular weight (Mw) mean values measured by gel permeation chromatography (GPC).
However, for a compound whose Mn cannot be accurately measured by GPC due to its small molecular weight, the molecular weight obtained from the chemical structure of the compound is adopted as the Mn of the compound. The same applies to Mw.
In the present specification, the measurement by gel permeation chromatography (GPC) uses HLC (registered trademark) -8020 GPC (Tosoh Corporation) as a measuring device, and TSKgel (registered trademark) Super Multipore HZ- as a column. Three H (4.6 mm ID x 15 cm, Tosoh Corporation) are used, and THF (tetrahydrofuran) is used as the eluent. The measurement conditions are a sample concentration of 0.45% by mass, a flow rate of 0.35 ml / min, a sample injection amount of 10 μl, and a measurement temperature of 40 ° C., and the measurement is performed using an RI detector.
The calibration curve is "Standard sample TSK standard, polystyrene": "F-40", "F-20", "F-4", "F-1", "A-5000", "A" of Tosoh Corporation. It is made from 8 samples of "-2500", "A-1000", and "n-propylbenzene".

The specific hydrophilic group-containing compound is preferably a water-soluble compound from the viewpoint of further improving the ejection property of the ink.
As used herein, the term "water-soluble" refers to the property of having a solubility of more than 1 g in 100 g of water at 25 ° C.

(Hydrophilic group)
The specific hydrophilic group-containing compound has a hydrophilic group which is at least one selected from the group consisting of an anionic group and a nonionic group.

The anionic group as the hydrophilic group may be an unneutralized anionic group or a neutralized anionic group.
Examples of the unneutralized anionic group include a carboxy group, a sulfo group, a sulfate group, a phosphonic acid group, a phosphoric acid group and the like.
Examples of the neutralized anionic group include a carboxy group salt, a sulfo group salt, a sulfate group salt, a phosphonic acid group salt, a phosphoric acid group salt, and the like.

As used herein, the neutralized anionic group refers to an anionic group in the form of a "salt" (eg, a salt of a carboxy group-COONa).
Neutralization of anionic groups can be carried out using, for example, alkali metal hydroxides (eg, sodium hydroxide, potassium hydroxide, etc.) and organic amines (eg, triethylamine, etc.).

Examples of the anionic group that can be contained in the specific hydrophilic group-containing compound include a carboxy group, a carboxy group salt, a sulfo group, a sulfo group salt, a sulfate group, and a sulfate group from the viewpoint of ink ejection property and storage stability. At least one selected from the group consisting of a salt, a phosphonic acid group, a salt of a phosphonic acid group, a phosphoric acid group, and a salt of a phosphoric acid group is preferable, and at least one selected from the group consisting of a carboxy group and a salt of a carboxy group. Is more preferable.
As the "salt" in the above-mentioned carboxy group salt, sulfo group salt, sulfate group salt, phosphonic acid group salt, and phosphoric acid group salt, an alkali metal salt or an organic amine salt is preferable, and the alkali metal salt. Is more preferable.
As the alkali metal in the alkali metal salt, K or Na is preferable.

When the specific hydrophilic group-containing compound has an anionic group, the degree of neutralization of the anionic group of the specific hydrophilic group-containing compound is preferably 50% to 100%, more preferably 70% to 95%, and 70% to 70%. 90% is more preferable.
Here, the degree of neutralization (%) is the total of "the number of unneutralized anionic groups and the number of neutralized anionic groups" in the entire specific hydrophilic group-containing compound contained in the ink. The ratio of "the number of neutralized anionic groups" to "", that is, the ratio [the number of neutralized anionic groups / (the number of unneutralized anionic groups + the number of neutralized anionic groups Number)]) refers to the value expressed as a percentage.
The degree of neutralization (%) of the specific hydrophilic group-containing compound is measured by neutralization titration.

When the specific hydrophilic group-containing compound has an anionic group, the neutralization degree of the anionic group in the entire specific hydrophilic group-containing compound and the specific particles is preferably 50% to 100%, preferably 70% to 95%. Is more preferable, and 70% to 90% is further preferable.
Here, the degree of neutralization refers to "the number of unneutralized anionic groups and the number of neutralized anionic groups in the entire specific hydrophilic group-containing compound and specific particles contained in the ink. Ratio of "number of neutralized anionic groups" to "total of" (ie, ratio [number of neutralized anionic groups / (number of unneutralized anionic groups + neutralized anionic) Number of groups)]).
The overall neutralization degree (%) of the specific hydrophilic group-containing compound and the specific particles is also measured by neutralization titration.

In the ink of the present disclosure, the total neutralization degree (%) of the specific hydrophilic group-containing compound and the specific particles is determined as follows.
First, an ink containing a specific hydrophilic group-containing compound and specific particles to be measured is prepared.
50 g of the prepared ink is centrifuged at 80,000 rpm (round per minute; the same applies hereinafter) under the conditions of 40 minutes. The supernatant produced by centrifugation is removed, and the precipitate (specific hydrophilic group-containing compound and specific particles) is collected.
Approximately 0.5 g of the recovered specific hydrophilic group-containing compound and specific particles are weighed in the container 1, and the weighed value W1 (g) is recorded. Next, a mixed solution of 54 mL of tetrahydrofuran (THF) and 6 mL of distilled water is added, and the weighed specific hydrophilic group-containing compound and specific particles are diluted to obtain a sample 1 for measuring the degree of neutralization.
The obtained sample 1 for measuring the degree of neutralization was titrated using a 0.1 N (= 0.1 mol / L) sodium hydroxide aqueous solution as a titrant, and the amount of the titrate required up to the equivalence point was F1 (. Record as mL). When a plurality of equivalence points are obtained in the titration, the maximum value among the plurality of titration liquid amounts required up to the plurality of equivalence points is set to F1 (mL). The product of F1 (mL) and the normality (0.1 mol / L) of the aqueous sodium hydroxide solution is the unneutralized anionic group among the anionic groups contained in the specific hydrophilic group-containing compound and the specific particles. Corresponds to the number of millimoles (eg, -COOH).
Further, about 0.5 g of the recovered specific hydrophilic group-containing compound and specific particles are weighed in the container 2, and the weighed value W2 (g) is recorded. Next, 60 mL of acetic acid is added to dilute the weighed specific hydrophilic group-containing compound and specific particles to obtain a sample 2 for measuring the degree of neutralization.
The obtained sample 2 for measuring the degree of neutralization was titrated using a 0.1 N (= 0.1 mol / L) acetic acid perchlorate solution as a titrant, and the amount of the titrate required up to the equivalence point was F2. Record as (mL). When a plurality of equivalence points are obtained in the titration, the maximum value among the plurality of titration liquid amounts required up to the plurality of equivalence points is set to F2 (mL). The product of F2 (mL) and the normality (0.1 mol / L) of the acetic acid perchlorate solution is the neutralized anionic group among the anionic groups contained in the specific hydrophilic group-containing compound and the specific particles. It corresponds to the number of mmol of (for example, -COONa).
Based on the measured values of "F1 (mL)" and "F2 (mL)", the degree of neutralization (%) of the anionic group is determined according to the following formula.
F1 (mL) × Normality of sodium hydroxide aqueous solution (0.1 mol / L) / W1 (g) + F2 (mL) × Normality of acetic acid perchlorate solution (0.1 mol / L) / W2 (g) = Total number of millimoles of anionic groups contained in a total of 1 g of the specific hydrophilic group-containing compound and specific particles (total number of millimoles of neutralized anionic groups and unneutralized anionic groups) (mmol / g).・ ・ (1)
F2 (mL) × Normality of acetic acid perchlorate solution (0.1 mol / L) / W2 (g) = Neutralized out of anionic groups contained in a total of 1 g of the specific hydrophilic group-containing compound and the specific particles. Millimole of anionic group (mmol / g) ... (2)
Neutralization degree (%) = (2) / (1) x 100

As the nonionic group as the hydrophilic group, a monovalent group containing a polyoxyalkylene chain is more preferable, and the following group (N1) is particularly preferable, from the viewpoint of ink ejection property and storage stability.

In the group (N1),
R ¹ represents a branched alkylene group ^{having 1 to 6 carbon atoms, R 2} represents a branched alkyl group having 1 to 6 carbon atoms, and L represents a single bond or a branched alkyl group. It represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, n represents an integer of 2 to 200, and * represents a bond position.

In group (N1), the number of carbon atoms of the alkylene group which may be branched having 1 to 6 carbon atoms represented by R ¹ is preferably 2 to 4, more preferably 2 or 3, It is particularly preferable that the value is 2 (that is, R ¹ is an ethylene group).
In the group (N1), the number of carbon atoms of the branched alkyl group having 1 to 6 carbon atoms represented by ^{R 2 is preferably 1 to 4, and 1 (that is, R 2} is). (Methyl group) is particularly preferable.
In the group (N1), as n, an integer of 2 to 150 is preferable, an integer of 2 to 100 is more preferable, an integer of 2 to 50 is further preferable, and an integer of 2 to 20 is particularly preferable.

In the group (N1), L represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a single bond or a substituent.

In the group (N1), the "carbon number" in the "divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent" represented by L is a substituent when it has a substituent. Indicates the carbon number of the entire group including.
The "carbon number" in the "divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent" represented by L is preferably 2 to 25, more preferably 4 to 20.

Among the groups (N1), the "divalent hydrocarbon group" in the "divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent" represented by L is an alkylene group or an arylene. Groups are preferred.

Among the groups (N1), the "substituent" in the "divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent" represented by L includes an alkoxy group, an alkoxycarbonyl group and an acyl group. Examples thereof include a group, an acyloxy group, a carboxy group, a salt of a carboxy group, a (meth) acryloyloxy group, a vinyl group, a vinyloxy group, and the like.

As L in the group (N1), a single bond or an alkylene group having 1 to 10 carbon atoms is preferable, a single bond or an alkylene group having 1 to 6 carbon atoms is more preferable, and a single bond is particularly preferable.

The compound (N2) described later as an example of the compound for introducing a nonionic group into a specific polymer can also be used for introducing a group (N1) into a specific hydrophilic group-containing compound.

The hydrophilic group contained in the specific hydrophilic group-containing compound is selected from the group consisting of a carboxy group, a salt of the carboxy group, and a monovalent group containing a polyoxyalkylene chain from the viewpoint of ink ejection property and storage stability. It is more preferable that the amount is at least one.

Further, the specific hydrophilic group-containing compound may have both an anionic group and a nonionic group as the hydrophilic group, but from the viewpoint of easiness of producing the specific hydrophilic group-containing compound, it is anionic. It preferably contains one of a group and a nonionic group and does not contain the other, and more preferably contains an anionic group and does not contain a nonionic group.

From the viewpoint of ink ejection property and storage stability, and ease of producing a specific hydrophilic group-containing compound, the hydrophilic group contained in the specific hydrophilic group-containing compound is at least one of a carboxy group and a salt of the carboxy group. Alternatively, it is more preferably a monovalent group containing a polyoxyalkylene chain, and further preferably at least one of a carboxy group and a salt of the carboxy group.

When the specific hydrophilic group-containing compound contains an anionic group as a hydrophilic group, the number of mmol of the anionic group per 1 g of the specific hydrophilic group-containing compound is the anionic base value of the specific hydrophilic group-containing compound ( In the case of mmol / g), the anionic base value of the specific hydrophilic group-containing compound is preferably 0.5 mmol / g or more, more preferably 0, from the viewpoint of further improving the ejection property and storage stability of the ink. It is 8.8 mmol / g or more, more preferably 1.0 mmol / g or more.
The upper limit of the anionic group value of the specific hydrophilic group-containing compound is not particularly limited, but the upper limit is, for example, 5.0 mmol / g, preferably 4.0 mmol / g, and more preferably 3.0 mmol / g.
The anionic base value of the specific hydrophilic group-containing compound and the anionic base value of the specific polymer described later can be measured by neutralization titration.

Further, when the specific hydrophilic group-containing compound contains an anionic group as a hydrophilic group, the number of millimoles of the anionic group per 1 g of the specific hydrophilic group-containing compound is set to the anionic group of the specific hydrophilic group-containing compound. When the valence is (mmol / g) and the number of mmol of anionic groups per 1 g of the specific polymer is the anionic base value (mmol / g) of the specific polymer,
The ratio of the anionic base value (mmol / g) of the specific polymer to the anionic base value (mmol / g) of the specific hydrophilic group-containing compound (anionic base value of the specific polymer / anionic group of the specific hydrophilic group-containing compound) The valence) is preferably less than 1, more preferably 0.8 or less, still more preferably 0.7 or less, and particularly preferably 0.6 or less.
When the ratio (anionic base value of the specific polymer / anionic base value of the specific hydrophilic group-containing compound) is less than 1, the effect of improving the ejection property and storage stability of the ink by the specific hydrophilic group-containing compound is more effective. Is demonstrated.

(Join U)
The specific hydrophilic group-containing compound has a bond U (ie, at least one bond selected from the group consisting of urethane bonds, urea bonds, thiourethane bonds, and thiourea bonds).
The specific hydrophilic group-containing compound is a reaction product of a bifunctional or higher (more preferably bifunctional to hexafunctional; the same applies hereinafter) isocyanate compound, a compound having an active hydrogen group, and at least one of water. Is preferable. Such reaction products have a bond U formed by the reaction of an isocyanate compound with at least one of a compound having an active hydrogen group and water.
In other words, the specific hydrophilic group-containing compound is
Containing or containing a bond U and a structure derived from a bifunctional or higher functional isocyanate compound.
It preferably contains a bond U, a structure derived from a bifunctional or higher functional isocyanate compound, and a structure derived from a compound having an active hydrogen group.
The specific hydrophilic group-containing compound more preferably contains _{a primary amino group (-NH 2) as a terminal group.}

As used herein, the active hydrogen group means a hydroxy group, a primary amino group, a secondary amino group, or a mercapto group.

In the present specification, the structure derived from a bifunctional or higher functional isocyanate compound means a structure obtained by removing all isocyanate groups from a bifunctional or higher functional isocyanate compound.
For example, the structure of m-xylylene diisocyanate (XDI), which is a bifunctional isocyanate compound, and the structure derived from XDI are as follows.

Further, the structure derived from the compound having an active hydrogen group means a structure in which all the active hydrogen groups are removed from the compound having an active hydrogen group.
For example, the structure of lysine corresponding to a compound having a hydrophilic group which is an anionic group (specifically, a carboxy group) and an active hydrogen group, and a structure derived from lysine are as follows.

Hereinafter, a preferred embodiment in the case where the specific hydrophilic group-containing compound is a reaction product of a bifunctional or higher functional isocyanate compound, a compound having an active hydrogen group, and at least one of water will be described.

Specific hydrophilic group-containing compounds are
Reaction product X1, of a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, and a bifunctional isocyanate compound,
Reaction product X2 of a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups.
A reaction product X3 of a trifunctional or higher functional isocyanate compound, a compound having a hydrophilic group and an active hydrogen group which are anionic or nonionic groups, and water, or a compound having three or more active hydrogen groups. Reaction product PX of a bifunctional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group which are anionic or nonionic groups, and water, a reaction product X4.
Is preferable.

In the reaction products X1 to X4, a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond is formed by the reaction of the active hydrogen group and / or water of the compound having an active hydrogen group with the isocyanate group of the isocyanate compound. Has been done.
Hereinafter, preferred embodiments of each reaction product will be described.

(Reaction product X1)
The reaction product X1 is a reaction product of a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, and a bifunctional isocyanate compound.
The compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, and the bifunctional isocyanate compound, which are the raw materials of the reaction product X1, may be only one kind, respectively, or 2 It may be more than a seed.
The embodiment in which the specific hydrophilic group-containing compound is the reaction product X1 is particularly preferable from the viewpoint of ink ejection property and storage stability, when the specific polymer contained in the specific particles is a specific chain polymer described later. is there.

As the bifunctional isocyanate compound that is the raw material of the reaction product X1, bifunctional isocyanate compounds (for example, compounds (1-1) to (1-20)) for forming a specific polymer described later can be used.

Examples of the compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, which are raw materials for the reaction product X1, include compounds for introducing anionic groups into a specific polymer described later (for example, α-amino acids and compounds). (H-1) to (H-33)) and a compound for introducing a nonionic group (for example, compound (N2)) can be used.
Examples of the compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, which are raw materials for the reaction product X1, include
A compound having two active hydrogen groups is preferable.
A compound having a hydrophilic group which is an anionic group and two active hydrogen groups is more preferable.
Compounds having a carboxy group and two active hydrogen groups are more preferred.
Amino acids with two primary amino groups (eg, lysine, etc.) or bis (hydroxymethyl) carboxylic acids (eg, 2,2-bis (hydroxymethyl) propionic acid (DMPA), 2,2-bis (eg,) (Hydroxymethyl) butyric acid (DMBA) and the like) are particularly preferable.

The reaction product X1 reacts, for example, with a raw material (a compound having a hydrophilic group which is an anionic group and two active hydrogen groups, and a bifunctional isocyanate compound) in an organic solvent (for example, ethyl acetate, methyl ethyl ketone, etc.). It is generated by letting it.

The terminal of the reaction product X1 is preferably an isocyanate group or a primary amino group, and more preferably a primary amino group. The primary amino group can be formed, for example, by an isocyanate group and a trace amount of water contained in the reaction system.

(Reaction product X2)
The reaction product X2 is a reaction between a trifunctional or higher (preferably trifunctional to hexafunctional; the same applies hereinafter) isocyanate compound and a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups. It is a product.
Only one type of trifunctional or higher functional isocyanate compound, which is a raw material of the reaction product X2, and a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, may be used. There may be two or more types.
The embodiment in which the specific hydrophilic group-containing compound is the reaction product X2 is particularly preferable from the viewpoint of ink ejection property and storage stability when the specific polymer contained in the specific particles is a specific crosslinked polymer described later. ..

As the trifunctional or higher functional isocyanate compound as the raw material of the reaction product X2, a trifunctional or higher functional isocyanate compound as a raw material of the specific crosslinked polymer that can be contained in the specific particles described later can be used.

The preferred embodiment of the compound having a hydrophilic group which is an anionic group or a nonionic group and an active hydrogen group, which is the raw material of the reaction product X2, is the same as the preferable embodiment in the raw material of the reaction product X1.

The reaction product X2 uses, for example, a raw material (a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group which are anionic or nonionic groups) as an organic solvent (for example, ethyl acetate, methyl ethyl ketone, etc.). ) Is produced by reacting in.

As the reaction product X2, a reaction product of a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group which is an anionic group and two active hydrogen groups is preferable.

The terminal of the reaction product X2 is preferably at least one of the above hydrophilic group and primary amino group.

(Reaction product X3)
The reaction product X3 is a reaction product of a trifunctional or higher functional isocyanate compound, a compound having a hydrophilic group and an active hydrogen group which are anionic or nonionic groups, and water.
Only one type of trifunctional or higher functional isocyanate compound, which is a raw material of the reaction product X3, and a compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, may be used. There may be two or more types.
The embodiment in which the specific hydrophilic group-containing compound is the reaction product X3 is particularly preferable from the viewpoint of ink ejection property and storage stability when the specific polymer contained in the specific particles is a specific crosslinked polymer described later. ..

The preferred embodiment of the raw material other than water among the raw materials of the reaction product X3 is the same as that of the raw material of the reaction product X2.
For the reaction product X3, for example, the raw material of the reaction product X2 described above (that is, a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group which are anionic or nonionic groups) is placed in water. It can be produced by reacting with.

The terminal of the reaction product X3 is preferably at least one of the above hydrophilic group and primary amino group.

(Reaction product X4)
The reaction product X4 is a reaction product PX of a compound having three or more active hydrogen groups, a bifunctional isocyanate compound, a hydrophilic group which is an anionic group or a nonionic group, and a compound having an active hydrogen group, and water. And, the reaction product.

The reaction product PX, which is the raw material of the reaction product X4, includes a compound having three or more active hydrogen groups, a bifunctional isocyanate compound, and a hydrophilic group and an active hydrogen group which are anionic or nonionic groups. A reaction product of the compound having the compound, and an isocyanate compound R in which a part of the isocyanate group derived from the bifunctional isocyanate compound remains unreacted or a mixture containing the isocyanate compound R is preferable.

The reaction product PX may be a compound similar to an isocyanate compound having a hydrophilic group introduced therein (that is, an isocyanate compound for introducing a hydrophilic group into a specific polymer), which will be described later.
The reaction product PX, which is the raw material of the reaction product X4, may be of only one type or of two or more types.
The embodiment in which the specific hydrophilic group-containing compound is the reaction product X4 is particularly preferable from the viewpoint of ink ejection property and storage stability when the specific polymer contained in the specific particles is a specific crosslinked polymer described later. ..

Examples of the compound having three or more active hydrogen groups which is a raw material of the reaction product PX include a compound having three or more active hydrogen groups which is a raw material of a crosslinked polymer described later (for example, compound (T-1)). ~ (T-13)) can be used.
As the bifunctional isocyanate compound that is the raw material of the reaction product PX, bifunctional isocyanate compounds (compounds (1-1) to (1-20)) for forming a specific polymer described later can be used.
Examples of the compound having a hydrophilic group and an active hydrogen group, which are anionic or nonionic groups, which are raw materials for the reaction product PX, include compounds for introducing anionic groups into a specific polymer described later (for example, α-amino acids and compounds). (H-1) to (H-33)) or a compound for introducing a nonionic group (for example, compound (N2)) can be used. Of these, a compound having a hydrophilic group and an active hydrogen group, which are nonionic groups, is preferable, and compound (N2) is particularly preferable.

The reaction product X4 can be produced, for example, by mixing the reaction product PX in water. As a result, the structure of the reaction product PX is changed, and the reaction product X4 is produced.
The mode of structural change of the reaction product PX is complex and not necessarily unique (see D116 Underwater Reaction Product Structure below). The reaction product X4 is, for example, a polymer compound formed by reacting an isocyanate group existing in the reaction product PX and an isocyanate group generated by hydrolysis of the reaction product PX with water. Can be mentioned.

The terminal of the reaction product X4 is preferably at least one of the above hydrophilic group and primary amino group.

The reaction product X4 includes a reaction product PX of a compound having three or more active hydrogen groups, a bifunctional isocyanate compound, a compound having a hydrophilic group and an active hydrogen group which are nonionic groups, and water. And, the reaction product of is preferred.

(Preferable structure of hydrophilic group-containing compound)
The hydrophilic group-containing compound preferably contains the following structural unit (X) (hereinafter, also simply referred to as “unit (X)”).

In unit (X),
U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond,
R represents a divalent hydrocarbon group having 1 to 20 carbon atoms.
X ¹ represents a (n + m) -valued linking group.
W represents a hydrophilic group which is an anionic group or a nonionic group.
n represents 0 or 1 and represents
m represents an integer of 2 to 6 and represents
(N + m) is an integer of 3 to 6 and
* Indicates the bond position with the group (UW), the bond position with the primary amino group, or the bond position with other structural units via urethane bond, urea bond, thiourethane bond, or thiourea bond. ..
In the base (UW),
U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond,
W represents a hydrophilic group which is an anionic group or a nonionic group.
L represents a single bond or a divalent linking group.
* Represents the connection position with the unit (X).

W in the unit (X) and W in the group (UW) may be the same or different.
The U in the unit (X) and the U in the group (UW) may be the same or different.
L in the unit (X) and L in the group (UW) may be the same or different.
A plurality of U existing in the unit (X) may be the same or different.
A plurality of Rs existing in the unit (X) may be the same or different.

The specific hydrophilic group-containing compound may contain a plurality of units (X). In this case, the plurality of units (X) may be the same or different.

The specific hydrophilic group-containing compound preferably contains a plurality of units (X). Thereby, the number average molecular weight of the specific hydrophilic group-containing compound can be made higher (for example, 2000 or more), and as a result, the ejection property and the storage stability of the ink can be further improved.
Here, the fact that the specific hydrophilic group-containing compound contains a plurality of units (X) means that the number of units (X) per molecule of the hydrophilic group-containing compound is a plurality of units.

The hydrophilic group-containing compound may contain a plurality of groups (UW). In this case, the plurality of units (UW) may be the same or different.
The preferred embodiment of W in the unit (X) and W in the group (UW) present in the hydrophilic group-containing compound is the same as the preferred embodiment of the above-mentioned "hydrophilic group possessed by the specific hydrophilic group-containing compound". Is.

In the unit (X), U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond. In the unit (X), U is preferably a urethane bond or a urea bond.

In the unit (X), the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R may have an alicyclic structure or an aromatic ring structure.
Further, in the unit (X), the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R may have a substituent. In this case, the "carbon number" in the "divalent hydrocarbon group having 1 to 20 carbon atoms" means the total carbon number of the group including the substituent.
Examples of the substituent include an alkoxy group, an alkoxycarbonyl group, an acyl group, an acyloxy group, and the like.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R include an alkylene group, an arylene group, an alkylene arylene group, an arylene alkylene arylene group, an alkylene arylene alkylene group, etc., which may contain an alicyclic structure. Can be mentioned.

The structure of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R is preferably a structure derived from a bifunctional isocyanate compound.
Specific examples of the bifunctional isocyanate compound include bifunctional isocyanate compounds (for example, compounds (1-1) to (1-20)) for forming a specific chain polymer that can be contained in specific particles described later. ..

In the unit (X), n represents 0 or 1, m represents an integer of 2 to 6, and (n + m) is an integer of 3 to 6.

In the unit (X), ^{the structure of the (n + m) -valent linking group represented by X 1} is preferably a structure derived from a compound having 2 to 6 active hydrogen groups.
As the compound having 2 to 6 active hydrogen groups, a compound having 3 to 6 active hydrogen groups is preferable. Examples of the compound having 3 to 6 active hydrogen groups include compounds (T-1) to (T-13) which are raw materials for the specific crosslinked polymer described later.
As the compound having 2 to 6 active hydrogen groups, a compound having 2 active hydrogen groups and 1 hydrophilic group is also preferable. Examples of the compound having two active hydrogen groups and one hydrophilic group include compounds (H-31) to (H-33) which are compounds for introducing a hydrophilic group (compound for introducing an anionic group) described later. ).

Specific examples of the (n + m) -valued linking group represented by X ¹ include the following linking groups (XT-1) to (XT-13) and (XH-31) to (XH-32). In the linking groups (XT-4), (XT-5) and (XT-11), n1 represents an integer selected from 1 to 100.

The preferred embodiment of the hydrophilic group which is an anionic group or a nonionic group represented by W in the unit (X) is the same as the preferable embodiment of the above-mentioned "hydrophilic group possessed by the specific hydrophilic group-containing compound". is there.

In the unit (X), * is a bond position with a group (UW), a bond position with a primary amino group, or with another structural unit via a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond. Represents the bond position to bond.
Here, the other structural unit may be another unit (X) adjacent to this unit (X), or may be a structural unit other than the unit (X).

In the group (UW), U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond. In the unit (UW), U is preferably a urethane bond or a urea bond.

The preferred embodiment of the hydrophilic group which is an anionic group or a nonionic group represented by W in the group (UW) is the same as the preferable embodiment of the above-mentioned "hydrophilic group possessed by the specific hydrophilic group-containing compound". is there.

In the unit (X), L represents a single bond or a divalent linking group, preferably a single bond.
The preferred range of the divalent linking group represented by L is the same as the preferred range of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R.

Hereinafter, specific examples of the structure of the specific hydrophilic group-containing compound when the unit (X) is contained will be shown, but the structure of the specific hydrophilic group-containing compound is not limited to the following specific examples.

Each code in the specific example is synonymous with each code in the unit (X) and the group (UW).
In the specific examples below, not only the urethane bond, urea bond, thiourethane bond, or thiourea bond existing in the structural unit, but also the urethane bond, urea bond, thiourethane bond, or thiourea bond existing between the structural units is also referred to as a symbol. Represented by "U".
In a specific example, each of a plurality of codes (for example, "U") existing in one molecule may be the same or different.

In the unit (1), the specific hydrophilic group-containing compound in the case where n is 0 and m is 3, for example, may have the following structure.

Further, the specific hydrophilic group-containing compound when a plurality of units (1) when n is 0 and m is 3 is contained includes at least one of the following six structural units. In this case, other structural units may be included, if necessary.

Specifically, the above six units are
A unit whose three ends are all * (bonding positions with other structural units) (one combination),
Units (two combinations) in which one of the three ends is attached to a primary amino group or group (UW) and the rest are * (bonding positions with other structural units), and
Units in which two of the three ends are attached to a primary amino group or group (UW) and the rest are * (bonding positions with other structural units) (three combinations)
Is.

The specific hydrophilic group-containing compound containing a plurality of units (1) when n is 0 and m is 4, includes at least one of the following 10 structural units. This specific hydrophilic group-containing compound may contain other structural units, if necessary.

Specifically, the above 10 units are
A unit whose four ends are all * (bonding positions with other structural units) (one combination),
A unit (two combinations) in which one of the four ends is attached to a primary amino group or group (UW) and the rest is * (bonding position with other structural units).
Units (three combinations) in which two of the four ends are attached to a primary amino group or group (UW) and the rest are * (bonding positions with other structural units), and
Units in which three of the four ends are attached to a primary amino group or group (UW) and the rest are * (bonding positions with other structural units) (4 combinations)
Is.

As described above, the content of the specific hydrophilic group-containing compound is 0.01% by mass to 1% by mass with respect to the total amount of the ink.
When the content of the specific hydrophilic group-containing compound is in the above range, the effects of ink ejection property and storage stability are exhibited.

<Specific particles>
Specific particles include specific polymers (ie, polymers having at least one of urethane and urea bonds).

(Specific polymer)
The specific particles contain at least one specific polymer.
The specific polymer has at least one of a urethane bond and a urea bond.
The specific polymer may be a linear polymer having no crosslinked structure (hereinafter, also referred to as "specific chain polymer"), or a polymer having a crosslinked structure (for example, a three-dimensional crosslinked structure) (hereinafter, "" It may also be a "specific crosslinked polymer").
The chain polymer may contain a cyclic structure such as an aliphatic ring, an aromatic ring, or a heterocycle in the main chain.
For the three-dimensional cross-linked structure that the specific cross-linked polymer can have, the three-dimensional cross-linked structure described in International Publication No. 2016/052053 may be referred to.

The specific polymer is preferably a water-insoluble compound. When the specific polymer is a water-insoluble compound, the specific polymer is more likely to be present in the specific particles.
As used herein, the term "water-insoluble" refers to the property of having a solubility of 1 g or less in 100 g of water at 25 ° C.

(Specific chain polymer)
As a specific chain polymer,
A reaction product of a bifunctional isocyanate compound, a compound having two active hydrogen groups, and at least one of water, or
A reaction product of a bifunctional isocyanate compound, a compound having two active hydrogen groups, at least one of water, and the other compound is preferable.
The bifunctional isocyanate compound, which is the raw material of the specific chain polymer, and the compound having two active hydrogen groups may be only one kind or two or more kinds, respectively.

Examples of the compound having two active hydrogen groups include a diol compound, a diamine compound, and a dithiol compound.
For example, a urethane bond is formed by the reaction of a bifunctional isocyanate compound and a diol compound.
Further, a urea bond is formed by the reaction of the bifunctional isocyanate compound and the diamine compound.
In addition, a urea bond is formed by the reaction of the bifunctional isocyanate compound with water.

In addition, as the above other compounds,
Of the compounds for introducing polymerizable groups described later, compounds containing only one active hydrogen group,
Of the isocyanate compounds into which a polymerizable group has been introduced, which will be described later, a compound containing only one isocyanate group.
Among the compounds for introducing hydrophilic groups described later, compounds containing only one active hydrogen group,
Of the isocyanate compounds into which a hydrophilic group has been introduced, which will be described later, a compound containing only one isocyanate group.
And so on.

Examples of the bifunctional isocyanate compound for forming the specific chain polymer include the following compounds (1-1) to (1-20).

Examples of the compound having two active hydrogen groups for forming the specific chain polymer include the following compounds (2-1) to (2-24).

Further, as the compound having two active hydrogen groups for forming the specific chain polymer, among the compounds for introducing a polymerizable group described later, a compound containing two active hydrogen groups and a hydrophilic group introduced later are introduced. Among the compounds for use, compounds containing two active hydrogen groups and the like can also be mentioned.

(Specific crosslinked polymer)
As a specific crosslinked polymer,
A reaction product of a trifunctional or higher functional isocyanate compound, a compound having two or more active hydrogen groups, and at least one of water, or
A reaction product of a trifunctional or higher functional isocyanate compound, at least one of a compound having two or more active hydrogen groups and water, and the other compound is preferable.
The trifunctional or higher functional isocyanate compound and the compound having two or more active hydrogen groups, which are the raw materials of the specific crosslinked polymer, may be only one kind or two or more kinds, respectively.

Other compounds mentioned above include
Of the compounds for introducing polymerizable groups described later, compounds containing only one active hydrogen group,
Of the isocyanate compounds into which a polymerizable group has been introduced, which will be described later, a compound containing only one isocyanate group.
Among the compounds for introducing hydrophilic groups described later, compounds containing only one active hydrogen group,
Of the isocyanate compounds into which a hydrophilic group has been introduced, which will be described later, a compound containing only one isocyanate group.
And so on.

When the specific particles contain a specific crosslinked polymer, the specific particles preferably include microcapsules (hereinafter, “MC”) containing a shell and a core made of the specific crosslinked polymer having a three-dimensional crosslinked structure.

Examples of the compound having two active hydrogen groups for forming the specific crosslinked polymer include a diol compound and a diamine, similarly to the compound having two active hydrogen groups for forming the specific chain polymer described above. Examples include compounds and dithiol compounds.
Examples of the compound having two or more active hydrogen groups for forming the specific crosslinked polymer include a trifunctional or higher functional polyol compound, a trifunctional or higher functional polyamine compound, and a trifunctional or higher functional polythiol compound.

The trifunctional or higher functional isocyanate compound for forming the specific crosslinked polymer is a compound having three or more active hydrogen groups (for example, a trifunctional or higher functional polyol compound, a trifunctional or higher functional polyamine compound, and a trifunctional or higher functional polythiol compound. ) And the bifunctional isocyanate compound, preferably the reaction product.
The number of moles (number of molecules) of a bifunctional isocyanate compound to be reacted with a compound having 3 or more active hydrogen groups is the number of moles of active hydrogen groups (equivalent number of active hydrogen groups) in a compound having 3 or more active hydrogen groups. ), 0.6 times or more, more preferably 0.6 times to 5 times, further preferably 0.6 times to 3 times, still more preferably 0.8 times to 2 times.

Examples of the bifunctional isocyanate compound for forming a trifunctional or higher functional isocyanate compound include the same as the bifunctional isocyanate compound for forming the specific chain polymer described above.

Examples of the compound having three or more active hydrogen groups for forming a trifunctional or higher functional isocyanate compound include compounds having the structures represented by the following (T-1) to (T-13). In the following structure, n represents an integer selected from 1 to 100.

Examples of the trifunctional or higher functional isocyanate compound used for forming the specific crosslinked polymer include adduct-type trifunctional or higher functional isocyanate compounds, isocyanurate-type trifunctional or higher functional isocyanate compounds, and biuret-type trifunctional or higher functional isocyanate compounds. Can be mentioned.
Commercially available products of adduct-type trifunctional or higher functional isocyanate compounds include Takenate® D-102, D-103, D-103H, D-103M2, P49-75S, D-110N, D-120N, D- 140N, D-160N (above, Mitsui Chemicals Co., Ltd.), Death Module (registered trademark) L75, UL57SP (Sumika Bayer Urethane Co., Ltd.), Coronate (registered trademark) HL, HX, L (Nippon Polyurethane Industry Co., Ltd.) ), P301-75E (Asahi Kasei Corporation) and the like.
Commercially available isocyanurate-type trifunctional or higher functional isocyanate compounds include Takenate (registered trademark) D-127N, D-170N, D-170HN, D-172N, D-177N (above, Mitsui Chemicals, Inc.). Sumijour N3300, Death Module (registered trademark) N3600, N3900, Z4470BA (above, Sumika Bayer Urethane Co., Ltd.), Coronate (registered trademark) HX, HK (above, Nippon Polyurethane Industry Co., Ltd.), Duranate (registered trademark) Examples thereof include TPA-100, TKA-100, TSA-100, TSS-100, TLA-100, TSE-100 (above, Asahi Kasei Corporation).
Commercially available products of biuret-type trifunctional or higher functional isocyanate compounds include Takenate (registered trademark) D-165N, NP1100 (above, Mitsui Chemicals, Inc.), and Death Module (registered trademark) N3200 (Sumika Bayer Urethane Co., Ltd.). ), Duranate (registered trademark) 24A-100 (Asahi Kasei Corporation) and the like.

As the trifunctional or higher functional isocyanate compound, a trifunctional to hexafunctional isocyanate compound is preferable.

(Preferable weight average molecular weight (Mw) of a specific polymer)
The weight average molecular weight (Mw) of the specific polymer is preferably 5000 or more, more preferably 7000 or more, still more preferably 8000 or more, from the viewpoint of ink ejection property and storage stability. It is particularly preferably 10,000 or more.
There is no particular limitation on the upper limit of Mw of the specific polymer. Examples of the upper limit of Mw of the specific polymer include 150,000, 100,000, 70,000, and 50,000.

The content of the specific polymer is preferably 10% by mass or more, more preferably 20% by mass or more, based on the solid content of the specific particles.
When the content of the specific polymer is 10% by mass or more with respect to the solid content of the specific particles, the ejection property and storage stability of the ink are further improved.
The content of the specific polymer may be 100% by mass with respect to the solid content of the specific particles, but is preferably 80% by mass or less, more preferably 70% by mass or less, and 50% by mass or less. Is particularly preferred.

(Polymerizable group)
The specific particles preferably have a polymerizable group.
When the specific particles have a polymerizable group, the polymerizable group contributes to curing the image by light, heat, infrared rays, or the like.
When the specific particles have a polymerizable group, the polymerizable group may or may not be covalently bonded to the specific polymer. In other words, when the specific particles have a polymerizable group, the specific polymer may have a polymerizable group, or the specific polymer may not have a polymerizable group.
The fact that the specific particles have a polymerizable group that is not covalently bonded to the specific polymer means that the specific particles include a compound having a polymerizable group (that is, a polymerizable compound).
When the specific particles contain a polymerizable group covalently bonded to the specific polymer, it means that the specific polymer itself has a polymerizable group.

As the polymerizable group, a photopolymerizable group or a thermopolymerizable group is preferable.
As the photopolymerizable group, a radically polymerizable group is preferable, a group containing an ethylenic double bond is more preferable, and a (meth) acryloyl group, an allyl group, a styryl group, or a vinyl group is further preferable. As the radically polymerizable group, a (meth) acryloyl group is particularly preferable from the viewpoint of radical polymerization reactivity and hardness of the film to be formed.
As the thermopolymerizable group, an epoxy group, an oxetanyl group, an aziridinyl group, an azetidinyl group, a ketone group, an aldehyde group, or a blocked isocyanate group is preferable.
When the specific particles have a polymerizable group, the specific particles may have only one type of polymerizable group or may have two or more types of polymerizable groups.
The fact that the specific particles have a polymerizable group can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR) analysis.

In the ink of the present disclosure, it is preferable that the specific particles contain a polymerizable compound (specifically, a photopolymerizable compound or a thermopolymerizable compound) from the viewpoint of further improving the hardness of the image.
A preferred embodiment of the polymerizable compound contained in the specific particles will be described later.

(Compound for introducing polymerizable groups)
When the specific polymer has a polymerizable group, the introduction of the polymerizable group into the specific polymer can be carried out by using a compound for introducing a polymerizable group.
As the compound for introducing a polymerizable group, a compound having a polymerizable group and an active hydrogen group can be used.
As the compound for introducing a polymerizable group, it is preferable to use a compound having one or more polymerizable groups and two or more active hydrogen groups.

The method for introducing the polymerizable group into the specific polymer is not particularly limited, but when synthesizing the specific polymer, the compound for introducing the polymerizable group (and, if necessary, the compound for introducing the hydrophilic group) together with the raw material of the specific polymer. ) Is particularly preferable.
The monomer for introducing a polymerizable group may be used alone or in combination of two or more.

As the compound for introducing a polymerizable group, for example, the compounds described in paragraphs 0075 to 0089 of International Publication No. 2016/052053 can also be used.

As the compound for introducing a polymerizable group, a compound represented by the following formula (ma) is preferable.
L ¹ Lc _m Z _n (ma)

In formula (ma), L ¹ represents a linking group of m + n valence, m and n are integers independently selected from 1 to 100, and Lc represents a monovalent ethylenically unsaturated group. Z represents an active hydrogen group.
L ¹ is a divalent or higher aliphatic group, a divalent or higher aromatic group, a divalent or higher heterocyclic group, -O-, -S-, -NH-, -N <, -CO-, -SO. -, -SO _2- or a combination thereof is preferable.
m and n are each independently preferably 1 to 50, more preferably 2 to 20, further preferably 3 to 10, and particularly preferably 3 to 5.
Examples of the monovalent ethylenically unsaturated group represented by Lc include an allyl group, a vinyl group, an acryloyl group, and a methacryloyl group.
Examples of the active hydrogen group represented by Z include a hydroxy group, an amino group (primary amino group and a secondary amino group), a mercapto group and the like, and a hydroxy group or a primary amino group is more preferable. It is more preferably a hydroxy group.

Hereinafter, examples of the compound for introducing a polymerizable group will be shown, but the compound for introducing a polymerizable group is not limited to the following examples. In addition, n in the compound (a-3) and (a-14) represents an integer selected from 1 to 90, for example.

(Isocyanate compound with a polymerizable group introduced)
When the specific polymer has a polymerizable group, the introduction of the polymerizable group into the specific polymer can also be carried out by using an isocyanate compound into which the polymerizable group has been introduced.
As an isocyanate compound into which a polymerizable group has been introduced,
A reaction product of the above-mentioned compound for introducing a polymerizable group and a bifunctional isocyanate compound;
A reaction product of the above-mentioned compound for introducing a polymerizable group and a trifunctional or higher functional isocyanate compound;
A reaction product of the above-mentioned compound for introducing a polymerizable group, a bifunctional isocyanate compound, and a compound having three or more active hydrogen groups;
And so on.
The raw materials of the isocyanate compound into which the polymerizable group has been introduced may be only one kind or two or more kinds, respectively.

(Hydrophilic group)
The specific particles (preferably the specific polymer in the specific particles) may further have a hydrophilic group which is at least one selected from the group consisting of anionic groups and nonionic groups.
When the specific particles have a hydrophilic group, the ejection property and storage stability of the ink are improved.
As the hydrophilic group, an anionic group is preferable because it is excellent in the effect of improving ink ejection property and storage stability.
For example, when comparing an anionic group and a nonionic group having the same molecular weight, the anionic group is more effective in improving ink ejection property and storage stability. That is, an anionic group (particularly preferably at least one selected from the group consisting of a carboxy group and a salt of a carboxy group) has an effect of improving ink ejection property and storage stability even when its molecular weight is small. It can be fully demonstrated.

Examples of the nonionic group that can be contained in the specific particles include a group having a polyether structure, and a monovalent group containing a polyoxyalkylene chain is preferable. The nonionic group that can be contained in the specific particles is more preferably the group (N1) described in the description of the specific hydrophilic group-containing compound.

The anionic group that can be contained in the specific particles may be an unneutralized anionic group, a neutralized anionic group, or both of them.
Examples of the unneutralized anionic group include a carboxy group, a sulfo group, a sulfate group, a phosphonic acid group, a phosphoric acid group and the like.
Examples of the neutralized anionic group include a carboxy group salt, a sulfo group salt, a sulfate group salt, a phosphonic acid group salt, a phosphoric acid group salt, and the like.

In the present specification, "the carboxy group is neutralized" means that the carboxy group as an anionic group is in the form of "salt" (for example, "-COONa"). The same applies to the sulfo group, sulfate group, phosphonic acid group, and phosphoric acid group as anionic groups.
Neutralization can be carried out using, for example, an alkali metal hydroxide (for example, sodium hydroxide, potassium hydroxide, etc.) or an organic amine (for example, triethylamine, etc.).

The anionic groups that the specific particles can have include a carboxy group, a carboxy group salt, a sulfo group, a sulfo group salt, a sulfate group, a sulfate group salt, and a phosphonic acid from the viewpoint of ink ejection property and storage stability. At least one selected from the group consisting of a group, a salt of a phosphonic acid group, a phosphoric acid group, and a salt of a phosphoric acid group is preferable, and at least one selected from the group consisting of a carboxy group and a salt of a carboxy group. Is more preferable.
As the "salt" in the above-mentioned carboxy group salt, sulfo group salt, sulfate group salt, phosphonic acid group salt, and phosphoric acid group salt, an alkali metal salt or an organic amine salt is preferable, and the alkali metal salt. Is more preferable.
As the alkali metal in the alkali metal salt, K or Na is preferable.

When the specific particles have a neutralized anionic group, the degree of neutralization of the anionic group (for example, carboxy group) contained in the specific particles is preferably 50% to 100%.
In the present specification, the "neutralization degree of anionic groups" refers to the number of moles of neutralized anionic groups and the number of moles of unneutralized anionic groups in the entire anionic groups of a specific particle. Ratio of the number of moles of neutralized anionic groups to the total of [number of moles of neutralized acid groups / (number of moles of neutralized acid groups + number of moles of unneutralized acid groups)] means.
When the neutralization degree of the anionic group is 50% or more, the ejection property and the storage stability of the ink are further improved.
The degree of neutralization of the anionic group is preferably 50% to 95%, more preferably 80% to 95%, and even more preferably 90% to 95%.
Neutralized anionic groups (ie, anionic groups in the form of salts) are basic. When the degree of neutralization of the anionic group is 95% or less, hydrolysis of the urethane bond and / or urea bond of the specific polymer can be further suppressed.
The degree of neutralization can be determined by neutralization titration.

When the specific polymer has the above hydrophilic groups, at least one of the hydrophilic groups of the specific polymer contained in the specific particles and at least one of the hydrophilic groups of the specific hydrophilic group-containing compound are groups of the same type. Is preferable. As a result, the specific polymer and the specific hydrophilic group-containing compound are more likely to interact with each other, and as a result, the ejection property and storage stability of the ink are further improved.

Here, not only the relationship between a specific hydrophilic group (for example, carboxy group) and the specific hydrophilic group (for example, carboxy group), but also the specific hydrophilic group (for example, carboxy group) and the specific hydrophilic group thereof. The relationship with salts (eg-COONa) shall also be included in the concept of "similar groups".

Among them, in a preferred embodiment, the hydrophilic group contained in the specific polymer contained in the specific particles is at least one of the carboxy group and the salt thereof, and the hydrophilic group contained in the specific hydrophilic group-containing compound is the carboxy group and the salt thereof. Is at least one aspect of.

(Compound for introducing hydrophilic group)
When the specific polymer in the specific particles has a hydrophilic group, the introduction of the hydrophilic group into the specific polymer can be performed by using a compound for introducing a hydrophilic group.
As the compound for introducing a hydrophilic group, a compound having a hydrophilic group and an active hydrogen group can be used.
As the compound for introducing a hydrophilic group, it is preferable to use a compound having one or more hydrophilic groups and two or more active hydrogen groups.

Among the hydrophilic group-introducing compounds, the anionic group-introducing compounds include α-amino acids (specifically, lysine, alanine, arginine, aspartic acid, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, etc. Amino acids such as leucine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine) can be mentioned.
Examples of the anionic group-introducing compound include the following specific examples (compounds (H-1) to (H-33)) in addition to the above-mentioned α-amino acid.

As the compound for introducing an anionic group, an inorganic base such as sodium hydroxide or potassium hydroxide; an organic base such as triethylamine; or the like may be used to neutralize at least a part of the anionic group.

Among the compounds for introducing a hydrophilic group, the compound for introducing a nonionic group is preferably a compound having a polyether structure, and more preferably a compound having a polyoxyalkylene chain.
As the compound having a polyoxyalkylene chain, the following compound (N2) is preferable.

In compound (N2),
R ¹ represents a branched alkylene group ^{having 1 to 6 carbon atoms, R 2} represents a branched alkyl group having 1 to 6 carbon atoms, and L represents a single bond or a branched alkyl group. It represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, and n represents an integer of 2 to 200.

In the compound ^(N2), the R ^{1, R} 2, L, and n a preferred embodiment, in the aforementioned groups ^(N1), the same as the preferred embodiment of R ^{1, R} 2, L, and n.

(Isocyanate compound with a hydrophilic group introduced)
When the specific polymer in the specific particles has a hydrophilic group, the introduction of the hydrophilic group into the specific polymer can also be performed by using an isocyanate compound into which the hydrophilic group has been introduced.
As an isocyanate compound into which a hydrophilic group has been introduced,
The reaction product of the above-mentioned compound for introducing a hydrophilic group and a bifunctional isocyanate compound;
A reaction product of the above-mentioned compound for introducing a hydrophilic group and a trifunctional or higher functional isocyanate compound;
A reaction product of the above-mentioned compound for introducing a hydrophilic group, a bifunctional isocyanate compound, and a compound having three or more active hydrogen groups;
And so on.
The raw material of the isocyanate compound into which the hydrophilic group has been introduced may be only one kind or two or more kinds, respectively.

Specific examples of the isocyanate compound into which a hydrophilic group has been introduced include an adduct of trimethylolpropane (TMP), m-xylylene diisocyanate (XDI) and polyethylene glycol monomethyl ether (EO) (for example, manufactured by Mitsui Kagaku Co., Ltd.). Takenate (registered trademark) D-116N) can be mentioned.

In the ink of the present disclosure, from the viewpoint of further improving the ejection property and storage stability of the ink, the specific polymer and the specific hydrophilic group-containing compound contained in the specific particles have a structure derived from the same type of bifunctional isocyanate compound. Moreover, it is preferable to have a structure derived from the same type of compound having a hydrophilic group which is an anionic group or a nonionic group and an active hydrogen group. That is, generally speaking, it is preferable that the specific polymer and the specific hydrophilic group-containing compound have a common structural skeleton. As a result, the specific polymer and the specific hydrophilic group-containing compound are more likely to interact with each other, and as a result, the ejection property and storage stability of the ink are further improved.

Here, the structure derived from the bifunctional isocyanate compound means a structure obtained by removing two isocyanate groups from the bifunctional isocyanate compound as described above.
Further, the concept of "structure derived from a bifunctional isocyanate compound" referred to here is a structure derived from a bifunctional isocyanate compound contained in the structure of a trifunctional or higher functional isocyanate compound (for example, D110 described later). (For example, a structure derived from XDI) is also included.

Further, with respect to the concept of "a compound of the same type having a hydrophilic group and an active hydrogen group which are anionic or nonionic groups", a specific anionic group (for example, a carboxy group) and a specific compound having an active hydrogen group and a specific compound. The relationship between an anionic group (eg, -COONa) and a compound having an active hydrogen group is also included in the concept of "similar compounds".

(Polymerizable compound)
The specific particles preferably contain a polymerizable compound (for example, a photopolymerizable compound or a thermopolymerizable compound) as a compound having a polymerizable group (for example, a photopolymerizable group or a thermopolymerizable group). According to this aspect, the hardness of the image is further improved.
When the specific particles contain a polymerizable compound, the specific particles may contain only one type of polymerizable compound or two or more types. When the specific particles contain a polymerizable compound, the polymerizable group of the polymerizable compound functions as a polymerizable group of the specific particles.
In the embodiment in which the specific particles contain a polymerizable compound, the specific polymer may have a polymerizable group.

As the polymerizable compound that can be contained in the specific particles, the compounds described in paragraphs 097 to 0105 of International Publication No. 2016/052053 may be used.

As the polymerizable compound that can be contained in the specific particles, a photopolymerizable compound that polymerizes by irradiation with light or a thermopolymerizable compound that polymerizes by irradiation with heating or infrared rays is preferable. As the photopolymerizable compound, a radically polymerizable compound having a radically polymerizable ethylenic double bond is preferable.
The polymerizable compound that can be contained in the specific particles may be any of a polymerizable monomer, a polymerizable oligomer, and a polymerizable polymer, but from the viewpoint of improving the curing sensitivity of the film and the hardness of the film, the polymerizable monomer is used. Is preferable. Among them, more preferable polymerizable compounds are a photopolymerizable monomer included in the concept of a photopolymerizable compound and a thermopolymerizable monomer included in the concept of a thermopolymerizable compound.

When the specific particles contain a photopolymerizable compound as the polymerizable compound, the specific particles preferably further contain a photopolymerization initiator described later.
When the specific particles contain a thermosetting compound as the polymerizable compound, the specific particles preferably further contain a photothermal converter, a thermosetting accelerator, or a photothermal converter and a thermosetting accelerator, which will be described later.

The content of the polymerizable compound (preferably the polymerizable monomer; the same applies hereinafter) that can be contained in the specific particles (the total amount when two or more kinds are contained) is from the viewpoint of improving the curing sensitivity of the film and the hardness of the film. The solid content of the specific particles is preferably 10% by mass to 90% by mass, more preferably 20% by mass to 80% by mass, still more preferably 30% by mass to 70% by mass.

From the viewpoint of further improving the adhesion of the image to the substrate, at least one of the polymerizable compounds (for example, photopolymerizable compounds) that can be contained in the specific particles is a polymerizable compound having a cyclic structure (hereinafter, “cyclic polymerization”). It is also preferably a "sex compound").

From the viewpoint of further improving the adhesion of the image to the substrate, at least one of the polymerizable compounds (for example, photopolymerizable compounds) that can be contained in the specific particles has one or more cyclic structures in one molecule. It is preferably a polymerizable compound containing two or more (meth) acryloyl groups (hereinafter, also referred to as “bifunctional or higher cyclic polymerizable compound”).
As a bifunctional or higher cyclic polymerizable compound,
Tricyclodecanedimethanol di (meth) acrylate,
Bisphenol A Ethylene Oxide (EO) Adduct Di (Meta) Acrylate,
Bisphenol A Propylene Oxide (PO) Adduct Di (Meta) Acrylate,
Ethoxybisphenol A di (meth) acrylate,
Alkoxylated dimethylol tricyclodecandi (meth) acrylate,
Alkoxyated cyclohexanone dimethanol di (meth) acrylate,
Cyclohexanone dimethanol di (meth) acrylate, and the like can be mentioned.

When the specific particles contain a polymerizable compound, the ratio of the bifunctional or higher functional cyclic polymerizable compound to the entire polymerizable compound is preferably 10% by mass to 100% by mass, more preferably 30% by mass to 100% by mass. 40% by mass to 100% by mass is particularly preferable.

The specific particles include a bifunctional or lower polymerizable compound (preferably a bifunctional or lower polymerizable monomer; the same applies hereinafter) and a trifunctional or higher functional polymerizable compound (preferably a trifunctional or higher polymerizable monomer; the same applies hereinafter). .) And may be included.
When the specific particles contain a bifunctional or lower polymerizable compound and a trifunctional or higher functional polymerizable compound, the bifunctional or lower polymerizable compound contributes to the adhesion of the film to the base material and is trifunctional or higher. It is considered that the polymerizable compound of the above contributes to the improvement of the hardness of the film.

The molecular weight of the polymerizable compound is preferably 100 to 100,000, more preferably 100 to 30,000, still more preferably 100 to 10,000, still more preferably 100 to 4000, still more preferably, as a weight average molecular weight. Is 100 to 2000, more preferably 100 to 1000, still more preferably 100 to 900, still more preferably 100 to 800, and particularly preferably 150 to 750.

-Polymerizable monomer-
Examples of the polymerizable monomer that can be contained in the specific particles include a photopolymerizable monomer that polymerizes and cures by irradiation with light, and a thermopolymerizable monomer that polymerizes and cures by irradiation with heat or infrared rays.
When a photopolymerizable monomer is contained as the polymerizable compound, it is preferable to include a photopolymerization initiator described later. When a thermopolymerizable monomer is contained as the polymerizable compound, it is preferable to include a photothermal converter, a thermosetting accelerator, or a photothermal converter and a thermosetting accelerator, which will be described later.

-Photopolymerizable monomer-
The photopolymerizable monomer includes a polymerizable monomer having a radically polymerizable ethylenically unsaturated bond (that is, a radically polymerizable monomer) and a polymerizable monomer having a cationically polymerizable cationically polymerizable group (that is, a cationically polymerizable monomer). ) Can be selected.

Examples of radically polymerizable monomers include acrylate compounds, methacrylate compounds, styrene compounds, vinylnaphthalene compounds, N-vinyl heterocyclic compounds, unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.
The radically polymerizable monomer is preferably a compound having an ethylenically unsaturated group.
When the specific particles contain a radically polymerizable monomer, the specific particles may contain only one type of radically polymerizable monomer or may contain two or more types of radically polymerizable monomers.

Examples of the acrylate compound include 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, tridecyl acrylate, 2-phenoxyethyl acrylate (PEA), and bis (4-acryloxypoly). Ethoxyphenyl) Propane, Oligoester Acrylate, Epoxy Acrylate, Isobornyl Acrylate (IBOA), Dicyclopentenyl Acrylate, Dicyclopentenyloxyethyl Acrylate, Dicyclopentanyl Acrylate, Cyclic Trimethylol Propaneformal Acrylate, 2- (2) -Ethoxyethoxy) ethyl acrylate, 2- (2-vinyloxyethoxy) ethyl acrylate, octyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 4-t-butylcyclohexyl acrylate, Isoamyl acrylate, stearyl acrylate, isoamyl still acrylate, isostearyl acrylate, 2-ethylhexyl diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hydrophthalic acid, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxy Propropylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, vinyl ether acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyphthalic acid, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, lactone-modified acrylate, acryloyl Monofunctional acrylate compounds such as morpholin, acrylamide, substituted acrylamide (eg, N-methylol acrylamide, and diacetone acrylamide);

Polyethylene glycol diacrylate, polypropylene glycol diacrylate, polytetramethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (HDDA), 1,9 -Nonandiol diacrylate (NDDA), 1,10-decanediol diacrylate (DDDA), 3-methylpentadiol diacrylate (3MPDDA), neopentyl glycol diacrylate, tricyclodecanedimethanol diacrylate, bisphenol A ethylene oxide ( EO) adduct diacrylate, bisphenol A propylene oxide (PO) adduct diacrylate, ethoxylated bisphenol A diacrylate, hydroxypineopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethylol tricyclodecandide Acrylate, Polytetramethylene glycol diacrylate, alkoxylated cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, cyclohexanone dimethanol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate , Dipropylene glycol diacrylate, tripropylene glycol diacrylate (TPGDA), neopentyl glycol propylene oxide adduct diacrylate and other bifunctional acrylate compounds;

Trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate, dimethylolpropane tetraacrylate, dipentaerythritol penta Acrylate, dipentaerythritol hexaacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, glycerin propoxytriacrylate, ethoxylated Examples thereof include trifunctional or higher functional acrylate compounds such as dipentaerythritol hexaacrylate, caprolactam-modified dipentaerythritol hexaacrylate, propoxylated glycerin triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

Examples of the methacrylate compound include methyl methacrylate, n-butyl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, methoxypolyethylene glycol methacrylate, methoxytriethylene glycol methacrylate, hydroxyethyl methacrylate, phenoxyethyl methacrylate, cyclohexyl methacrylate and the like. Monofunctional methacrylate compound;

Examples thereof include bifunctional methacrylate compounds such as polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and tetraethylene glycol dimethacrylate.

Examples of the styrene compound include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, p-methoxy-β-methylstyrene and the like.

Examples of the vinylnaphthalene compound include 1-vinylnaphthalene, methyl-1-vinylnaphthalene, β-methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene, 4-methoxy-1-vinylnaphthalene and the like.

Examples of the N-vinyl heterocyclic compound include N-vinylcarbazole, N-vinylpyrrolidone, N-vinylethylacetamide, N-vinylpyrrole, N-vinylphenothiazine, N-vinylacetanilide, N-vinylethylacetamide, and N-vinylsuccinic acid. Examples thereof include imide, N-vinylphthalimide, N-vinylcaprolactam, and N-vinylimidazole.

Examples of other radically polymerizable monomers include N-vinylamides such as allylglycidyl ether, diallyl phthalate, triallyl trimellitate, and N-vinylformamide.

Among these radically polymerizable monomers, the less than bifunctional radically polymerizable monomers include 1,6-hexanediol diacrylate (HDDA), 1,9-nonanediol diacrylate (NDDA), and 1,10-decanediol. Diacrylate (DDDA), 3-Methylpentadiol diacrylate (3MPDDA), Neopentyl glycol diacrylate, Tricyclodecanedimethanol diacrylate, Diethylene glycol diacrylate, Tetraethylene glycol diacrylate, Dipropylene glycol diacrylate, Tripropylene glycol At least one selected from diacrylate (TPGDA), cyclohexanone dimethanol diacrylate, alkoxylated hexanediol diacrylate, polyethylene glycol diacrylate, and polypropylene glycol diacrylate is preferable.
Examples of the trifunctional or higher functional radically polymerizable monomer include trimethyl propantriacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, ditrimethylolpropanetetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and ethoxylated. Trimethylol Propane Triacrylate, Propoxylated Trimethylol Propane Triacrylate, Caprolactone Modified Trimethylol Propane Triacrylate, Pentaerythritol Tetraacrylate, Pentaerythritol ethoxytetraacrylate, Glycerin Propoxytriacrylate, Ethylated Dipentaerythritol Hexaacrylate, Caprolactam Modified Dipenta At least one selected from erythritol hexaacrylate, propoxylated glycerin triacrylate, ethoxylated trimethylol propanetriacrylate, and propoxylated trimethylol propanetriacrylate is preferred.

As a combination of a difunctional or lower radically polymerizable monomer and a trifunctional or higher functional radical polymerizable monomer, a combination of a bifunctional acrylate compound and a trifunctional acrylate compound, a bifunctional acrylate compound and a pentafunctional acrylate compound Examples thereof include a combination with and a combination of a monofunctional acrylate compound and a tetrafunctional acrylate compound.

As a radically polymerizable monomer,
Monomers with a cyclic structure are preferred;
Preferred compounds of the above-mentioned bifunctional or higher functional cyclic polymerizable compounds, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, isobornyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, dicyclopentanyl acrylate, ethoxy Isocyanuric acid triacrylate or ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate is more preferred;
The preferred compound group of the above-mentioned bifunctional or higher functional cyclic polymerizable compounds, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, or dicyclopentanyl acrylate is more preferable;
The preferred compound group of the above-mentioned bifunctional or higher functional cyclic polymerizable compounds is particularly preferable.

In addition to the radically polymerizable monomers listed above, Shinzo Yamashita, "Handbook of Crosslinking Agents" (1981, Taiseisha); Kiyomi Kato, "UV / EB Curing Handbook (Raw Materials)" (1985, Polymer Publications); Radtech Study Group, "Applications and Markets of UV / EB Curing Technology", p. 79, (1989, CMC); Eiichiro Takiyama, "Polyester Resin Handbook", (1988, Nikkan Kogyo) Commercially available products described in (Newspaper) and the like, and radically polymerizable and crosslinkable monomers known in the industry can be used.

Examples of cationically polymerizable monomers include epoxy compounds, vinyl ether compounds, and oxetane compounds.
Examples of the cationically polymerizable monomer include compounds having at least one olefin, thioether, acetal, thioxane, thietan, aziridine, N heterocycle, O heterocycle, S heterocycle, P heterocycle, aldehyde, lactam, or cyclic ester group. preferable.

Cationic polymerizable monomers include JV Crivello et al., "Advances in Polymer Science", 62, pages 1 to 47 (1984), Lee et al., "Handbook of Epoxy Resins", McGraw Hill Book Company, New York (1967), and The compounds described in "Epoxy Resin Technology", (1968) by PF Bruins et al. May be used.

Examples of the photopolymerizable monomer include JP-A-7-159883, JP-A-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-134011, and Japanese Patent Laid-Open No. Photocurable polymerizable monomers used in the photopolymerizable compositions described in each publication such as Table 2004-514014 are known, and these can also be applied as polymerizable monomers that can be contained in specific particles. it can.

As the photopolymerizable monomer, a commercially available product on the market may be used.
Examples of commercially available photopolymerizable monomers include AH-600 (bifunctional), AT-600 (bifunctional), UA-306H (six-functional), UA-306T (six-functional), and UA-306I (six-functional). ), UA-510H (10 functional), UF-8001G (bifunctional), DAUA-167 (bifunctional), light acrylate NPA (bifunctional), light acrylate 3EG-A (bifunctional) (above, Kyoeisha Chemical Co., Ltd. )), SR339A (PEA, monofunctional), SR506 (IBOA, monofunctional), CD262 (bifunctional), SR238 (HDDA, bifunctional), SR341 (3MPDDDA, bifunctional), SR508 (bifunctional), SR306H (2) (Functional), CD560 (2 functional), SR833S (2 functional), SR444 (3 functional), SR454 (3 functional), SR492 (3 functional), SR499 (3 functional), CD501 (3 functional), SR502 (3 functional) , SR9020 (3 functional), CD9021 (3 functional), SR9035 (3 functional), SR494 (4 functional), SR399E (5 functional) (above, Sartmer), A-NOD-N (NDDA, 2 functional), A -DOD-N (DDDA, bifunctional), A-200 (bifunctional), APG-400 (bifunctional), A-BPE-10 (bifunctional), A-BPE-20 (bifunctional), A-9300 (Trifunctional), A-9300-1CL (Trifunctional), A-TMPT (Trifunctional), A-TMM-3L (Trifunctional), A-TMMT (4 Functional), AD-TMP (4 Functional) (End) , Shin-Nakamura Chemical Industry Co., Ltd., UV-7510B (trifunctional) (Nippon Synthetic Chemistry Co., Ltd.), KAYARAD DPCA-30 (6 functionals), KAYARAD DPEA-12 (6 functionals) Co., Ltd.) and the like.
Other polymerizable monomers include NPGPODA (neopentyl glycol propylene oxide adduct diacrylate), SR531, SR285, SR256 (above, Sartmer), A-DHP (dipentaerythritol hexaacrylate, Shin-Nakamura Chemical Industry Co., Ltd.). ), Aronix (registered trademark) M-156 (Toa Synthetic Co., Ltd.), V-CAP (BASF), Viscort # 192 (Osaka Organic Chemical Industry Co., Ltd.) and the like can be preferably used.
Among these commercially available products, SR506, SR833S, A-9300, or A-9300-CL, which are photopolymerizable monomers having a cyclic structure, are particularly preferable, and SR833S is particularly preferable.

-Thermal polymerizable monomer-
The thermopolymerizable monomer can be selected from the group of polymerizable monomers that can be polymerized by heating or irradiation with infrared rays. Examples of the thermopolymerizable monomer include compounds such as epoxy, oxetane, aziridine, azetidine, ketone, aldehyde, and block isocyanate.

Among the above, the epoxy compounds include 1,4-butanediol diglycidyl ether, 3- (bis (glycidyloxymethyl) methoxy) -1,2-propanediol, limonene oxide, 2-biphenylglycidyl ether, 3,4. -Epoxycyclohexylmethyl-3', 4'-epoxycyclohexanecarboxylate, epoxide derived from epichlorohydrin-bisphenol S, epoxidized styrene, epoxide derived from epichlorohydrin-bisphenol F, derived from epichlorohydrin-bisphenol A Epoxides, epoxidized novolak, alicyclic diepoxides and other epoxides with less than two functions;
Examples include trifunctional or higher functional epoxy compounds such as polyglycidyl ester of polybasic acid, polyglycidyl ether of polyol, polyglycidyl ether of polyoxyalkylene glycol, polyglycidyl ester of aromatic polyol, urethane polyepoxy compound, and polyepoxy polybutadiene. Be done.

Examples of the oxetane compound include 3-ethyl-3-hydroxymethyl-1-oxetane, 1,4 bis [3-ethyl-3-oxetanylmethoxy] methyl] benzene, 3-ethyl-3-phenoxymethyl-oxetane, and bis ([[]. 1-Ethyl (3-oxetanyl)] methyl) ether, 3-ethyl-3-[(2-ethylhexyloxy) methyl] oxetane, 3-ethyl-[(triethoxysilylpropoxy) methyl] oxetane, 3,3-dimethyl -2- (p-methoxyphenyl) -oxetane and the like can be mentioned.

Examples of the blocked isocyanate compound include a compound in which the isocyanate compound is inactivated with a blocking agent (active hydrogen-containing compound).
Examples of the isocyanate compound include hexamethylene diisocyanate, isophorone diisocyanate, toluyl diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate trimeric, trimethylhexylylene diisocyanate, diphenylmethane diisocyanate, and dicyclohexyl. Commercially available isocyanates such as methanediisocyanate, hydrogenated xylylene diisocyanate, Takenate (registered trademark; Mitsui Kagaku Co., Ltd.), Duranate (registered trademark; Asahi Kasei Co., Ltd.), Bayhydur (registered trademark; Bayer AG), or these. A combination of difunctional or higher isocyanates is preferred.

Examples of the blocking agent include lactam [eg, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc.], oxime [eg, acetoxime, methylethylketooxime (MEK oxime), methylisobutylketooxime (MIBK oxime), cyclohexanone oxime, etc.] , Amines [eg aliphatic amines (dimethylamine, diisopyramine, di-n-propylamine, diisobutylamine, etc.), alicyclic amines (methylhexylamine, dicyclohexylamine, etc.), aromatic amines (aniline, diphenylamine, etc.)], Aliper alcohols [eg methanol, ethanol, 2-propanol, n-butanol, etc.], phenols and alkylphenols [eg phenol, cresol, ethylphenol, n-propylphenol, isopropylphenol, n-butylphenol, octylphenol, nonylphenol, xylenol, diisopropyl Phenol, di-t-butylphenol, etc.], imidazole [eg, imidazole, 2-methylimidazole, etc.], pyrazole [eg, pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, etc.], imine [eg, ethyleneimine, polyethyleneimine, etc.] ], Active methylene [for example, dimethyl malonate, diethyl malonate, diisopropyl malate, acetylacetone, methyl acetoacetate, ethyl acetoacetate, etc.], Blocking described in JP-A-2002-309217 and JP-A-2008-239890. Agents, as well as mixtures of two or more of these. Among them, as the blocking agent, oxime, lactam, pyrazole, active methylene, or amine is preferable.

As the block isocyanate compound, a commercially available product on the market may be used, for example, Trixene (registered trademark) BI7982, BI7641, BI7462, BI7950, BI7960, BI9791 (Baxenden Chemicals LTD), Bayer (registered trademark; Bayer). AG) is preferably used. In addition, the compound group described in paragraph 0064 of International Publication No. 2015/158654 is also preferably used.

The specific particles containing the polymerizable monomer can be produced, for example, by emulsifying a mixture of an oil phase component containing the specific chain polymer and the polymerizable monomer and an aqueous phase component.

The molecular weight of the polymerizable monomer is preferably 100 to 4000, more preferably 100 to 2000, still more preferably 100 to 1000, still more preferably 100 to 900, still more preferably, as a weight average molecular weight. Is 100 to 800, and particularly preferably 150 to 750.

(Photopolymerization initiator)
The specific particles may contain at least one of the photopolymerization initiators.
Specific when the specific particles have a photopolymerizable group (preferably a radically polymerizable group) as a polymerizable group (particularly when the specific particles contain a photopolymerizable compound (more preferably a radically polymerizable compound)). The particles preferably contain at least one of the photopolymerization initiators.

When the specific particles contain a photopolymerization initiator, an image having high sensitivity to active energy rays, excellent hardness, and excellent adhesion to a substrate can be obtained.
Specifically, when the specific particles contain a photopolymerization initiator, one specific particle has both a polymerizable group and a photopolymerization initiator. Therefore, since the distance between the polymerizable group and the photopolymerization initiator becomes short, the curing sensitivity of the film (hereinafter, also simply referred to as “sensitivity”) is compared with the case where a conventional photocurable composition is used. Is improved. As a result, a film having better hardness and better adhesion to the substrate is formed.

Further, when the specific particles contain a photopolymerization initiator, the photopolymerization initiator (for example, solubility in water) which has been difficult to use due to its high sensitivity but low dispersibility in water or low solubility in water has been conventionally performed. Photopolymerization initiator) having a temperature of 1.0% by mass or less at 25 ° C. can be used. As a result, the range of choices for the photopolymerization initiator used is widened, and the range of choices for the light source used is also widened. Therefore, the curing sensitivity can be improved as compared with the conventional case.
Specific examples of the photopolymerization initiator described above, which have high sensitivity but low dispersibility in water or low solubility, include carbonyl compounds and acylphosphine oxide compounds described below. , Acylphosphine oxide compounds are preferred.
As described above, the ink of the present disclosure can be contained in the ink of the present disclosure, which is an aqueous composition, by including a substance having low solubility in water in the specific particles. This is also one of the advantages of the inks of the present disclosure.

In addition, the ink in which the specific particles contain a photopolymerization initiator is also excellent in storage stability as compared with the conventional photocurable composition. It is considered that the reason for this is that the agglutination or precipitation of the photopolymerization initiator is suppressed by the inclusion of the photopolymerization initiator in the specific particles.

As the photopolymerization initiator that can be contained in the specific particles, a known photopolymerization initiator can be appropriately selected and used.
A photopolymerization initiator is a compound that absorbs light (that is, active energy rays) to generate a radical that is a polymerization initiator.

Known compounds can be used as the photopolymerization initiator, but preferred photopolymerization initiators include (a) carbonyl compounds such as aromatic ketones, (b) acylphosphine oxide compounds, and (c) aromatic onium salt compounds. (D) Organic peroxide, (e) thio compound, (f) hexaarylbiimidazole compound, (g) ketooxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, ( Examples thereof include (k) an active ester compound, (l) a compound having a carbon halogen bond, and (m) an alkylamine compound.

As these photopolymerization initiators, the above compounds (a) to (m) may be used alone or in combination of two or more.

Preferred examples of the (a) carbonyl compound, (b) acylphosphine oxide compound, and (e) thio compound include "RADITION CURING IN POLYMER SCIENCE AND TECHNOLOGY", J. Mol. P. FOUASSIER, J. Mol. F. RABEK (1993), pp. Examples thereof include the compounds having a benzophenone skeleton or a thioxanthone skeleton described in 77 to 117.
More preferable examples include an α-thiobenzophenone compound described in Japanese Patent Publication No. 47-6416, a benzoin ether compound described in Japanese Patent Publication No. 47-3981, and an α-substituted benzoin compound described in Japanese Patent Publication No. 47-22326. Benzene derivative described in JP-A-47-23664, alloylphosphonic acid ester described in JP-A-57-30704, dialkoxybenzophenone described in JP-A-60-26483, JP-A-60-26403, JP-A. Benzene ethers described in 1987-81345, Japanese Patent Publication No. 1-34242, US Pat. No. 4,318,791 pamphlet, α-aminobenzophenones described in European Patent No. 0284561A1, JP-A-2-211452. P-di (dimethylaminobenzoyl) benzene described in JP-A, thio-substituted aromatic ketones described in JP-A-61-194062, acylphosphine sulfides described in JP-A-2-9597, JP-A-2-9596. Examples thereof include the acylphosphins described, the thioxanthones described in Japanese Patent Publication No. 63-61950, and the coumarins described in Japanese Patent Publication No. 59-42864.
Further, the polymerization initiator described in JP-A-2008-105379 or JP-A-2009-114290 is also preferable.

Examples of commercially available photopolymerization initiators include IRGACURE® 184,369,500, 651, 819, 907, 1000, 1300, 1700, 1870, DAROCUR® 1173, 2959, 4265, ITX, LUCIRIN (registered trademark) TPO [all manufactured by BASF], ESACURE (registered trademark) KTO37, KTO46, KIP150, EDB [all above, all manufactured by Lamberti], H-Nu (registered trademark) 470, 470X [all above. Spectra Group Limited], Omnipol TX, 9210 [all above, IGM Resins B. et al. V. , SPEEDCURE 7005, 7010, 7040 [above, manufactured by LAMBSON] and the like.

Among these photopolymerization initiators, (a) carbonyl compound or (b) acylphosphine oxide compound is more preferable, and specifically, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (for example, BASF). IRGACURE® 819), 2- (dimethylamine) -1- (4-morpholinophenyl) -2-benzyl-1-butanone (eg, IRGACURE® 369, BASF), 2 -Methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (eg, IRGACURE® 907, manufactured by BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (eg, BASF). IRGACURE (registered trademark) 184), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (for example, DAROCUR (registered trademark) TPO, LUCIRIN (registered trademark) TPO (all manufactured by BASF)) Can be mentioned.
Among these, (b) an acylphosphine oxide compound is preferable, and a monoacylphosphine oxide compound (particularly preferably 2,) is preferable as the inclusion photopolymerization initiator from the viewpoint of improving sensitivity and compatibility with LED light. 4,6-trimethylbenzoyl-diphenyl-phosphine oxide) or a bisacylphosphine oxide compound (particularly preferably, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide) is more preferable.
The wavelength of the LED light is preferably 355 nm, 365 nm, 385 nm, 395 nm, or 405 nm.

Further, from the viewpoint of suppressing migration, a polymer-type photopolymerization initiator is also preferable as the photopolymerization initiator.
Examples of the polymer-type photopolymerization initiator include the above-mentioned Omnipol TX, 9210; SPEEDCURE 7005, 7010, 7040 ;.

The specific particles containing the photopolymerization initiator can be produced, for example, by emulsifying a mixture of an oil phase component containing the specific chain polymer and the photopolymerization initiator and an aqueous phase component.

The content of the photopolymerization initiator is preferably 0.1% by mass to 25% by mass, more preferably 0.5% by mass to 20% by mass, still more preferably 1% by mass or more, based on the solid content of the specific particles. It is 15% by mass.

(Sensitizer)
The specific particles may contain at least one of the sensitizers.
When the specific particles contain at least one photopolymerization initiator, the specific particles preferably contain at least one sensitizer.
When the specific particles contain a sensitizer, the decomposition of the photopolymerization initiator by irradiation with active energy rays can be further promoted.
A sensitizer is a substance that absorbs a specific active energy ray and becomes an electron-excited state. The sensitizer in the electron-excited state comes into contact with the photopolymerization initiator and causes actions such as electron transfer, energy transfer, and heat generation. This promotes chemical changes in the photopolymerization initiator, that is, decomposition, radicals, acid or base production, and the like.

Examples of the sensitizer include benzophenone, thioxanthone, isopropylthioxanthone, anthraquinone, 3-acylcoumarin derivative, terphenyl, styrylketone, 3- (aroylmethylene) thiazolin, eosin, eosin, rhodamine, erythrosin and the like. ..
As the sensitizer, a compound represented by the general formula (i) described in JP-A-2010-24276 and a compound represented by the general formula (I) described in JP-A-6-107718. Can also be suitably used.
Among the above, as the sensitizer, at least one selected from thioxanthone, isopropylthioxanthone, and benzophenone is preferable from the viewpoint of compatibility with LED light and reactivity with a photopolymerization initiator, and from thioxanthone and isopropylthioxanthone. At least one selected is more preferred, and isopropylthioxanthone is even more preferred.
When the specific particles contain a sensitizer, the sensitizer may be contained alone or in combination of two or more.

When the specific particles contain a sensitizer, the content of the sensitizer is preferably 0.1% by mass to 20% by mass, and 0.2% by mass to 15% by mass, based on the solid content of the specific particles. Is more preferable, and 0.3% by mass to 10% by mass is further preferable.

The specific particles containing the photopolymerization initiator and the sensitizer are obtained, for example, by emulsifying a mixture of an oil phase component containing the specific chain polymer, the photopolymerization initiator and the sensitizer, and an aqueous phase component. Can be manufactured.

(Photothermal converter)
When the specific particles contain a heat-polymerizable compound (preferably a heat-polymerizable monomer) as the polymerizable compound, the specific particles may contain at least one of a photothermal converter.
A photothermal converter is a compound that absorbs infrared rays and the like to generate heat and polymerizes and cures a heat-polymerizable compound. As the photothermal converter, a known compound can be used.

As the photothermal converter, an infrared absorber is preferable. Examples of the infrared absorber include polymethylindolium, indocyanine green, polymethine pigment, croconium pigment, cyanine pigment, merocyanine pigment, squarylium pigment, chalcogenopyrroallylidene pigment, metal thiolate complex pigment, and bis (calcogenopyrilo) polymethine pigment. , Oxyindolidin pigment, bisaminoallyl polymethine pigment, indridin pigment, pyririum pigment, quinoid pigment, quinone pigment, phthalocyanine pigment, naphthalocyanine pigment, azo pigment, azomethine pigment, carbon black and the like.

The specific particles containing the photothermal converter can be produced, for example, by emulsifying a mixture of an oil phase component containing a specific chain polymer and a photothermal converter and an aqueous phase component.

The photothermal converter may be used alone or in combination of two or more.
The content of the photothermal converter is preferably 0.1% by mass to 25% by mass, more preferably 0.5% by mass to 20% by mass, and 1% by mass with respect to the solid content of the specific particles. It is more preferably% to 15% by mass.

(Thermosetting accelerator)
When the specific particles contain a heat-polymerizable compound (preferably a heat-polymerizable monomer) as the polymerizable compound, the specific particles may contain at least one of a thermosetting accelerator.
The thermosetting accelerator is a compound that catalytically accelerates the thermosetting reaction of a thermosetting compound (preferably a thermosetting monomer).

Known compounds can be used as the thermosetting accelerator. As the heat curing accelerator, an acid or a base, or a compound that generates an acid or a base by heating is preferable, and for example, a carboxylic acid, a sulfonic acid, a phosphoric acid, an aliphatic alcohol, a phenol, an aliphatic amine, an aromatic amine, or an imidazole. (For example, phenylimidazole, 2-methylimidazole), pyrazole and the like can be mentioned.

The specific particles containing the thermosetting accelerator can be produced, for example, by emulsifying a mixture of an oil phase component containing a specific chain polymer and a thermosetting accelerator and an aqueous phase component.

The thermosetting accelerator may be used alone or in combination of two or more.
The content of the thermosetting accelerator is preferably 0.1% by mass to 25% by mass, more preferably 0.5% by mass to 20% by mass, based on the solid content of the specific particles. It is more preferably mass% to 15% by mass.

In the ink of the present disclosure, the solid content of the specific particles is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more with respect to the solid content of the ink. It is more preferably 80% by mass or more, and even more preferably 85% by mass or more.
As a result, the ejection property and storage stability of the ink are further improved, and the adhesion between the image and the base material is further improved.

In the ink of the present disclosure, the solid content of the specific particles is preferably 1% by mass to 50% by mass, more preferably 3% by mass to 40% by mass, and 5% by mass with respect to the total amount of the ink. It is more preferably ~ 30% by mass.
When the solid content of the specific particles is 1% by mass or more with respect to the total amount of the ink, the adhesion between the image and the base material is further improved.
Further, when the solid content of the specific particles is 50% by mass or less with respect to the total amount of the ink, the ejection property and the storage stability of the ink are further improved.

The volume average dispersed particle size of the specific particles is not particularly limited, but is preferably 0.01 μm to 10.0 μm, more preferably 0.01 μm to 5 μm, from the viewpoint of ink ejection property and storage stability. It is more preferably 0.05 μm to 1 μm, further preferably 0.05 μm to 0.5 μm, still more preferably 0.05 μm to 0.3 μm.
In the present specification, the "volume average dispersed particle size" refers to a value measured by a light scattering method. The volume average dispersed particle size of specific particles is measured by the light scattering method using, for example, LA-960 (HORIBA, Ltd.).

<Water>
The inks of the present disclosure contain water.
Water is a dispersion medium for specific particles (dispersibles).
The content of water in the ink of the present disclosure is not particularly limited, but the content of water is preferably 10% by mass to 99% by mass, and more preferably 20% by mass to 95% by mass, based on the total amount of the ink. It is by mass%, more preferably 30% by mass to 90% by mass, and particularly preferably 50% by mass to 90% by mass.

<Color material>
The ink of the present disclosure may be an ink containing at least one kind of coloring material (so-called “colored ink”) or an ink containing no coloring material (so-called “clear ink”).
When the ink contains a coloring material, it is preferable that the coloring material is contained outside the specific particles (that is, the specific particles do not contain the coloring material).
The color material is not particularly limited, and can be arbitrarily selected from known color materials such as pigments, water-soluble dyes, and disperse dyes. Among these, it is more preferable to contain a pigment from the viewpoint of excellent weather resistance and excellent color reproducibility.

The pigment is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include known organic pigments and inorganic pigments, resin particles dyed with a dye, a commercially available pigment dispersion and a surface. Treated pigments (for example, those in which the pigment is dispersed in water, a liquid compound, an insoluble resin, or the like as a dispersion medium, or those in which the pigment surface is treated with a resin, a pigment derivative, or the like) can also be mentioned.
Examples of organic pigments and inorganic pigments include yellow pigments, red pigments, magenta pigments, blue pigments, cyan pigments, green pigments, orange pigments, purple pigments, brown pigments, black pigments and white pigments.

When a pigment is used as the coloring material, a pigment dispersant may be used if necessary.
When a pigment is used as the coloring material, a self-dispersing pigment having a hydrophilic group on the surface of the pigment particles may be used as the pigment.
As for the color material and the pigment dispersant, paragraphs 0180 to 0200 of JP-A-2014-040529 and paragraphs 0122 to 0129 of International Publication No. 2016/052053 can be referred to as appropriate.

When the ink of the present disclosure contains a coloring material, the content of the coloring material is preferably 0.1% by mass to 20% by mass, more preferably 0.5% by mass to 10% by mass, and 0, based on the total amount of the ink. .5% by mass to 5% by mass is particularly preferable.

<Other ingredients>
The ink of the present disclosure may contain other components other than those described above, if necessary.
Other components may or may not be contained in the specific particles.

(Organic solvent)
The ink of the present disclosure may contain an organic solvent.
When the ink of the present disclosure contains an organic solvent, the adhesion between the image and the substrate can be further improved.
When the ink of the present disclosure contains an organic solvent, the content of the organic solvent is preferably 0.1% by mass to 10% by mass, preferably 0.1% by mass to 5% by mass, based on the total amount of the ink. Is more preferable.
Specific examples of the organic solvent are as follows.
-Alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.),
-Polyhydric alcohols (eg ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, 2- Methylpropanediol, etc.),
-Polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, tripropylene Glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl Ether etc.),
-Amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, penta) Methyldiethylenetriamine, tetramethylpropylenediamine, etc.),
Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.),
Heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, etc.),
-Sulfoxides (eg, dimethyl sulfoxide, etc.),
-Sulfones (eg, sulfolane, etc.),
・ Others (urea, acetonitrile, acetone, etc.)

(Surfactant)
The ink of the present disclosure may contain at least one type of surfactant.
When the ink of the present disclosure contains a surfactant, the wettability of the ink to the substrate is improved.
Examples of surfactants include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, alkylbenzene sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, and polyoxyalkylene alkyl ethers. Phosphates, polyoxyalkylene alkyl phenyl ethers, polyoxyethylene polyoxypropylene glycols, glycerin esters, sorbitan esters, polyoxyethylene fatty acid amides, amine oxides and the like can be mentioned.
Among these, as the surfactant, at least one surfactant selected from alkyl sulfates, alkyl sulfonates, and alkyl benzene sulfonates is preferable, and alkyl sulfates are particularly preferable.
The surfactant is preferably an alkyl sulfate having an alkyl chain length of 8 to 18 from the viewpoint of dispersibility of specific particles, and sodium dodecyl sulfate (SDS, alkyl chain length: 12) and sodium cetyl sulfate (SCS). , Alkyl chain length: 16), more preferably at least one selected.

Further, as other surfactants other than the above-mentioned surfactants, those described in JP-A-62-173463 and JP-A-62-183457 are also mentioned. For example, other surfactants include nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and siloxanes. Can be mentioned.
Further, as a surfactant, an organic fluoro compound can also be mentioned.
The organic fluoro compound is preferably hydrophobic. Examples of the organic fluorocompound include a fluorine-based surfactant, an oil-like fluorine-based compound (for example, fluorine oil), and a solid fluorine compound resin (for example, tetrafluoride ethylene resin). 8th to 17th columns), and those described in JP-A-62-135826 can be mentioned.

In addition, since the ink of the present disclosure is excellent in ejection property and storage stability, it is possible that the ink substantially does not contain a surfactant (for example, an anionic surfactant).
Here, "substantially free" means that the content is less than 1% by mass (preferably less than 0.1% by mass) with respect to the total amount of the ink.
The aspect in which the ink does not substantially contain an anionic surfactant has an advantage that foaming of the ink can be suppressed, an advantage that the water resistance of the image can be improved, an advantage that whitening due to bleed-out after image formation can be suppressed, and the like. Has. Further, in particular, when a pigment dispersion having an anionic dispersible group is used for the preparation of the ink, the ion concentration in the system is increased by the anionic surfactant, and the ionization degree of the anionic pigment dispersant is decreased. Therefore, it also has an advantage that the decrease in dispersibility of the pigment can be suppressed.

(Polymerization inhibitor)
The ink of the present disclosure may contain a polymerization inhibitor.
When the ink of the present disclosure contains a polymerization inhibitor, the storage stability of the ink can be further improved.
Polymerization inhibitors include p-methoxyphenols, quinones (eg, hydroquinone, benzoquinone, methoxybenzoquinone, etc.), phenothiazines, catechols, alkylphenols (eg, dibutylhydroxytoluene (BHT), etc.), alkylbisphenols, dimethyldithiocarbamine. Zinc acid, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionic acid esters, mercaptobenzimidazole, phosphites, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), Examples thereof include 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl (TEMPOL), cuperon Al, and tris (N-nitroso-N-phenylhydroxylamine) aluminum salts.
Among these, at least one selected from p-methoxyphenol, catechols, quinones, alkylphenols, TEMPO, TEMPOL, cuperon Al, and tris (N-nitroso-N-phenylhydroxylamine) aluminum salt is preferable, and p. -At least one selected from methoxyphenol, hydroquinone, benzoquinone, BHT, TEMPO, TEMPOL, cuperon Al, and tris (N-nitroso-N-phenylhydroxylamine) aluminum salts is more preferred.

(UV absorber)
The ink of the present disclosure may contain an ultraviolet absorber.
When the ink of the present disclosure contains an ultraviolet absorber, the weather resistance of the image and the like can be further improved.
Examples of the ultraviolet absorber include known ultraviolet absorbers such as benzotriazole-based compounds, benzophenone-based compounds, triazine-based compounds, and benzoxazole-based compounds.

Further, the ink of the present disclosure has a polymerizable compound, a photopolymerization initiator, and a resin outside the specific particles, if necessary, from the viewpoints of image hardness, adhesion between the image and the substrate, and ink ejection property. Etc. may be contained.
These components are preferably water-soluble or water-dispersible.
Further, "the ink contains a polymerizable compound outside the specific particles" means that the ink contains a polymerizable compound that is not contained in the specific particles. The same applies when a photopolymerization initiator, a water-soluble resin, a water-dispersible resin, or the like is contained outside the specific particles.

Examples of the polymerizable compound that can be contained outside the specific particles include the polymerizable compounds described in paragraphs 0148 to 0156 of International Publication No. 2016/052053.
Examples of the polymerizable compound that can be contained outside the specific particles include compounds having an ethylenically unsaturated group, acrylonitrile, styrene, unsaturated polyester, unsaturated polyether, unsaturated polyamide, and unsaturated urethane. Can be mentioned.
Among these, as the polymerizable compound that can be contained outside the specific particles, a compound having an ethylenically unsaturated group is preferable, and a compound having a (meth) acryloyl group is particularly preferable.

From the viewpoint of water solubility or water dispersibility, the polymerizable compound that can be contained outside the specific particles is selected from the group consisting of an amide structure, a polyethylene glycol structure, a polypropylene glycol structure, a carboxy group, and a salt of a carboxy group. A compound having at least one kind is preferable.

From the viewpoint of water solubility or water dispersibility, the polymerizable compounds that can be contained outside the specific particles include, for example, (meth) acrylate, sodium (meth) acrylate, potassium (meth) acrylate, N, N-. Dimethylacrylamide, N, N-diethylacrylamide, morpholine acrylamide, N-2-hydroxyethyl (meth) acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) Acrylate, 2-hydroxypropyl (meth) acrylate, glycerin monomethacrylate, N- [tris (3-acryloylaminopropyloxymethylene) methyl] acrylamide, diethylene glycol bis (3-acryloylaminoproyl) ether, polyethylene glycol di (meth) At least one selected from acrylates, polypropylene glycol di (meth) acrylates, compounds represented by the following general formulas (a) to (d), and trimethylolethane ethoxylated propantriacrylates (for example, SR9035 manufactured by Sartmer). Species are preferred, (meth) acrylic acid, N, N-dimethylacrylamide, N-2-hydroxyethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, glycerin monomethacrylate, N- [tris (3-acryloylamino) Propyloxymethylene) methyl] acrylamide, diethylene glycol bis (3-acryloylaminopoil) ether, polyethylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylate, according to the following general formulas (a) to (d). More preferably, the compound represented and at least one selected from the ethoxylated trimethyl propanetriacrylate (eg SR9035 manufactured by Sartmer).

In formula (a), the plurality of R ¹ is independently a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group, the plurality of R ² may independently represent a hydrogen atom or a methyl group, a plurality of L ¹ independently represents a single bond or a divalent linking group.
In the general formula (b), the plurality of R ³ may independently represent a hydrogen atom or a methyl group, to each of a plurality of L ² independently represents an alkylene group having 1 to 8 carbon atoms, plurality of k and p Represent each independently 0 or 1, and the plurality of m each independently represent an integer from 0 to 8, where at least one of k and p is 1.
In the general formula (c), the plurality of R ⁴ may independently represent a hydrogen atom or a methyl group, in each of the plurality of n independently represents an integer of 1 to 8, l is an integer of 0 or 1.
In the general formula (d), Z ¹ represents a residue of a hydrogen atom by removing the q hydroxyl groups of the polyol, q represents an integer of 3-6, the plurality of R ⁵ is independently a hydrogen atom or methyl It represents a group, an alkylene group having 1 to 8 carbon atoms in each of the plurality of L ³ independently.

Specific examples of the compounds represented by the general formulas (a) to (d) include compounds represented by the following AM-1 to AM-4.

The above AM-1 to AM-4 can be synthesized by the method described in Japanese Patent No. 5591858.

For the photopolymerization initiator and the resin that can be contained outside the specific resin, paragraphs 0139 to 0147 and 0157 of International Publication No. 2016/052053 can be referred to as appropriate.

<Preferable physical characteristics of ink>
The ink of the present disclosure preferably has a viscosity of 3 mPa · s to 15 mPa · s, more preferably 3 mPa · s to 13 mPa · s, when the ink is set to 25 ° C. to 50 ° C. In particular, the ink of the present disclosure preferably has a viscosity of 50 mPa · s or less when the temperature of the ink is 25 ° C. When the viscosity of the ink is in the above range, higher ejection properties can be realized.
The viscosity of the ink is a value measured using a viscometer (VISCOMETER TV-22, Toki Sangyo Co., Ltd.).

[Specific Example 1 of Ink Manufacturing Method (Manufacturing Method A)]
The method for producing the ink of the present disclosure is not particularly limited, but when the specific hydrophilic group-containing compound is any of the above-mentioned reaction products X1 to reaction product X4, the production method A shown below is preferable. Is.
In the production method A, an oil phase component containing an organic solvent and a specific polymer, or an oil phase component containing an organic solvent and a trifunctional or higher functional isocyanate compound, and an aqueous phase component containing water are mixed and emulsified. Has a step of forming specific particles,
When the specific hydrophilic group-containing compound is the reaction product X1 or the reaction product X2, the oil phase component contains the specific hydrophilic group-containing compound, and the specific hydrophilic group-containing compound is contained.
When the specific hydrophilic group-containing compound is the reaction product X3 or the reaction product X4, the aqueous phase component contains the specific hydrophilic group-containing compound.
According to this production method A, it is possible to produce an ink having excellent ejection properties and storage stability.

In the step of forming the specific particles, the specific particles are formed by mixing the above-mentioned oil phase component and the aqueous phase component and emulsifying the obtained mixture. The formed specific particles function as a dispersoid in the produced ink.
The water in the aqueous phase component functions as a dispersion medium in the produced ink.

Examples of the organic solvent contained in the oil phase component include ethyl acetate and methyl ethyl ketone.
It is preferable that at least a part of the organic solvent is removed in the process of forming the specific particles and after the formation of the specific particles.

From the viewpoint of curability of the image formed by the ink, the oil phase component introduces a polymerizable compound, a compound for introducing a polymerizable group (preferably a compound having a polymerizable group and an active hydrogen group), and a polymerizable group. It is preferable to contain at least one selected from the above-mentioned isocyanate compounds, and it is more preferable to contain a polymerizable compound.
When the oil phase component contains a polymerizable compound, the oil phase component is at least a compound for introducing a polymerizable group (preferably a compound having a polymerizable group and an active hydrogen group) and an isocyanate compound into which a polymerizable group has been introduced. One may be included.
In addition to the above components, the oil phase component may include, for example, a photopolymerization initiator, a sensitizer, an isocyanate compound into which a hydrophilic group has been introduced, and the like.

In the production method A, when the specific hydrophilic group-containing compound is the reaction product X1 or the reaction product X2, the oil phase component contains the specific hydrophilic group-containing compound.
In this case, for example, the reaction product X1 or the reaction product X2 is produced in an organic solvent to obtain a solution of the reaction product X1 or the reaction product X2, and the obtained solution is used as a part of the oil phase component. ..

The aqueous phase component is not particularly limited except that it contains water, and may be water alone.
The aqueous phase component may contain a component other than water.
For example, the aqueous phase component may contain a compound for introducing a hydrophilic group (preferably a compound having a hydrophilic group and an active hydrogen group).
Further, the aqueous phase component may contain a basic compound as a neutralizing agent for an unneutralized anionic group (carboxy group, sulfo group, phosphoric acid group, phosphonic acid group, sulfate group, etc.). .. Thereby, in the process of forming a specific particle, an anionic group neutralized (that is, an anionic group in the form of a salt; for example, a salt of a carboxy group, a salt of a sulfo group, a salt of a phosphoric acid group, a phosphonic acid group. Salt, sulfate group salt, etc.) can be formed.
When the basic compound (neutralizing agent) is used, it is preferable that the basic compound (neutralizing agent) is contained at least in the aqueous phase component.
Examples of the basic compound include inorganic bases such as sodium hydroxide and potassium hydroxide, and organic bases such as triethylamine. Among these, as the basic compound, inorganic bases such as sodium hydroxide and potassium hydroxide are preferable.
Examples of the salt in the anionic group in the form of a salt include alkali metal salts such as sodium salt and potassium salt; and organic amine salts such as triethylamine salt. Among these, alkali metal salts such as sodium salt and potassium salt are preferable as the salt in the anionic group in the form of salt.

In the production method A, when the specific hydrophilic group-containing compound is the reaction product X3 or the reaction product X4, the aqueous phase component contains the specific hydrophilic group-containing compound.
In this case, for example, a reaction product X3 or a reaction product X4 is produced in water to obtain an aqueous solution or an aqueous dispersion of the reaction product X3 or the reaction product X4, and the obtained aqueous solution or aqueous dispersion is used as an aqueous phase. Used as part of the ingredients.

The total amount of the oil phase component and the aqueous phase component excluding the organic solvent and water in the production method A corresponds to the solid content of the specific particles in the produced ink.
For the preferable range of the amount of each component that can be used in the production method A, the above-mentioned "ink" section can be referred to. At the time of this reference, the "content" and "solid content of specific particles" in the above-mentioned "ink" section are "amount used" and "organic solvent and water from oil phase component and aqueous phase component, respectively". Read as "total amount excluding".

In the step of forming the specific particles, the method of mixing the oil phase component and the aqueous phase component is not particularly limited, and examples thereof include mixing by stirring.

In the step of forming the specific particles, the emulsification method is not particularly limited, and examples thereof include emulsification by an emulsification device such as a homogenizer (for example, a disperser).
The rotation speed of the disperser in emulsification is, for example, 5,000 rpm to 20,000 rpm, preferably 10,000 rpm to 15,000 rpm.
The rotation time in emulsification is, for example, 1 minute to 120 minutes, preferably 3 minutes to 60 minutes, more preferably 3 minutes to 30 minutes, and even more preferably 5 minutes to 15 minutes.

The emulsification in the step of forming the specific particles may be carried out under heating.
By performing the emulsification under heating, specific particles can be formed more efficiently.
Further, by performing the emulsification under heating, at least a part of the organic solvent in the oil phase component can be easily removed from the mixture.
When emulsification is performed under heating, the heating temperature is preferably 35 ° C. to 70 ° C., more preferably 40 ° C. to 60 ° C.

In addition, the step of forming specific particles includes an emulsification step of emulsifying the mixture (for example, at a temperature of less than 35 ° C.) and a heating step of heating the emulsion obtained by the emulsification step (for example, at a temperature of 35 ° C. or higher). , May be included.
In the embodiment including the emulsification step and the heating step, the specific particles can be formed more efficiently, especially in the heating step.
Further, in the embodiment including the emulsification step and the heating step, at least a part of the organic solvent in the oil phase component can be easily removed from the mixture, especially in the heating step.
The heating temperature in the heating step is preferably 35 ° C. to 70 ° C., more preferably 40 ° C. to 60 ° C.
The heating time in the heating step is preferably 6 hours to 50 hours, more preferably 12 hours to 40 hours, and even more preferably 15 hours to 35 hours.

Further, the production method A may have other steps other than the step of forming the specific particles, if necessary.
Examples of other steps include a step of adding other components (pigments and the like) after the step of forming specific particles.
The other components (pigments, etc.) to be added are as described above as other components that can be contained in the ink.

[Specific Example 2 of Ink Manufacturing Method (Manufacturing Method B)]
When the specific hydrophilic group-containing compound is either the above-mentioned reaction product X3 or reaction product X4, the method for producing the ink of the present disclosure includes the following production method B.
Manufacturing method B is
An oil phase component containing an organic solvent and a specific polymer, an oil phase component containing an organic solvent and a trifunctional or higher functional isocyanate compound, and an aqueous phase component containing water.
To obtain an aqueous dispersion containing specific particles by mixing and emulsifying.
A step of adding a specific hydrophilic group-containing compound, which is a reaction product X3 or a reaction product X4, to the obtained aqueous dispersion, and
Have.
In the above-mentioned addition step in the production method B, not only the specific hydrophilic group-containing compound but also other components (pigments and the like) may be added to the aqueous dispersion.
This production method B can also be used to produce an ink having excellent ejection properties and storage stability.
In the production method B, the components that may be contained in the oil phase component and the aqueous phase component are the same as the components that may be contained in the oil phase component and the aqueous phase component in the production method A, respectively.
The preferable conditions of the production method B are the same as the preferable conditions of the production method A.

[Image formation method]
The image forming method of the present disclosure includes a step of applying the ink of the present disclosure described above onto a substrate (hereinafter, also referred to as a “giving step”).
The image forming method of the present disclosure may include other steps if necessary.
The image forming method of the present disclosure uses the ink of the present disclosure having excellent ejection properties and storage stability. Therefore, according to the image forming method of the present disclosure, an image can be stably formed on the base material.

(Granting process)
The applying step is a step of applying the ink of the present disclosure onto a base material.
As a mode for applying the ink on the base material, any of the modes using known methods such as a coating method, a dipping method, and an inkjet method may be adopted. Above all, the inkjet method is preferable in that a film (for example, an image) can be formed on various substrates (including a recording medium).

The base material is not particularly limited, and for example, a known base material provided as a support and a recording medium can be appropriately selected and used.
Examples of the base material include paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), a metal plate (for example, a metal plate such as aluminum, zinc, copper, etc.), and a plastic film (for example, polychloride). Vinyl (PVC: Polyvinyl Chloride) resin, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate (PET), polyethylene (PE: Polyethylene), polystyrene (PS) : Polystyrene), polypropylene (PP: Polypropylene), polycarbonate (PC: Polycarbonate), polyvinyl acetal, acrylic resin and other films), paper on which the above-mentioned metals are laminated or vapor-deposited, and above-mentioned metals are laminated or vapor-deposited. Examples include plastic films.

Further, as the base material, a textile base material can also be mentioned.
Materials for textile base materials include, for example, natural fibers such as cotton, silk, linen, and wool; chemical fibers such as viscose rayon and leocell; synthetic fibers such as polyester, polyamide, and acrylic; natural fibers, chemical fibers, and synthetic fibers. A mixture of at least two selected from the group consisting of fibers; and the like. As the textile base material, the textile base material described in paragraphs 0039 to 0042 of International Publication No. 2015/158592 may be used.

Specifically, as the base material, a polyvinyl chloride (PVC) base material, a polystyrene (PS) base material, a polycarbonate (PC) base material, a polyethylene terephthalate (PET) base material, a polypropylene (PP) base material, and an acrylic resin base material. A plastic base material such as a material is preferable.

Ink application by the inkjet method can be performed using a known inkjet recording device.
The inkjet recording device is not particularly limited, and a known inkjet recording device capable of achieving the desired resolution can be arbitrarily selected and used.
Examples of the inkjet recording device include a device including an ink supply system, a temperature sensor, and a heating means.
The ink supply system includes, for example, a source tank containing the ink of the present disclosure, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo type inkjet head. The piezo type inkjet head preferably has a multi-size dot of 1 pl to 100 pl, more preferably 8 pl to 30 pl, preferably 320 dpi (dot per inch) × 320 dpi to 4000 dpi × 4000 dpi (dot per inch), more preferably 400 dpi ×. It can be driven to discharge at a resolution of 400 dpi to 1600 dpi x 1600 dpi, more preferably 720 dpi x 720 dpi. In addition, dpi represents the number of dots per 2.54 cm (1 inch).

(Curing process)
When the specific particles in the ink of the present disclosure have a polymerizable group, the image forming method of the present disclosure is provided after the applying step and cures the ink applied on the substrate (hereinafter, also referred to as “curing step”). It is preferable to further include (referred to).
Since the cross-linking reaction (that is, polymerization reaction) of the specific particles proceeds by this curing step, the adhesion between the image and the substrate and the hardness of the image can be improved.
As a curing step, when the specific particles have a photopolymerizable group (and preferably a photopolymerization initiator), the curing step A of irradiating with active energy rays (light) is preferable, and the specific particles have a thermopolymerizable group. In the case of, the curing step B in which heating or irradiation with infrared rays is performed is preferable.

-Curing step A-
The curing step A is a step of irradiating the ink applied on the base material with active energy rays.
In the curing step A, by irradiating the ink applied on the base material with active energy rays, a photocrosslinking reaction (that is, a photopolymerization reaction) of specific particles in the ink proceeds, so that the image and the base material are combined. Adhesion and image hardness can be improved.

Examples of the active energy ray that can be used in the curing step A include ultraviolet rays (UV light), visible light, electron beam, and the like, and among these, UV light is preferable.

The peak wavelength of the active energy ray (light) is preferably 200 nm to 405 nm, more preferably 220 nm to 390 nm, and even more preferably 220 nm to 385 nm.
Further, it is preferably 200 nm to 310 nm, and preferably 200 nm to 280 nm.

Exposure surface illuminance when the active energy ray (light) is irradiated, for example, ^{10mW / cm 2 ~2000mW / cm 2} , preferably ^{20mW / cm 2 ~1000mW / cm 2} .
Exposure energy at the time of an active energy ray (light) is irradiated, for example, ^{10mJ / cm 2 ~2000mJ / cm 2} , preferably ^{20mJ / cm 2 ~1000mJ / cm 2} .

Mercury lamps, metal halide lamps, UV fluorescent lamps, gas lasers, solid-state lasers, and the like are widely known as sources for generating active energy rays (light).
Also, the replacement of the light source exemplified above with a semiconductor ultraviolet light emitting device is very useful both industrially and environmentally.
Among semiconductor ultraviolet light emitting devices, LEDs (Light Emitting Diodes) and LDs (Laser Diodes) are expected as light sources because of their small size, long life, high efficiency, and low cost.
As the light source, a metal halide lamp, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a medium pressure mercury lamp, a low pressure mercury lamp, an LED, or a bluish purple laser is preferable.
Among these, when the sensitizer and the photopolymerization initiator are used in combination, an ultra-high pressure mercury lamp capable of irradiating light at a wavelength of 365 nm, 405 nm, or 436 nm, and light irradiation at a wavelength of 365 nm, 405 nm, or 436 nm are possible. A high-pressure mercury lamp or an LED capable of irradiating light having a wavelength of 355 nm, 365 nm, 385 nm, 395 nm, or 405 nm is more preferable, and an LED capable of irradiating light having a wavelength of 355 nm, 365 nm, 385 nm, 395 nm, or 405 nm is most preferable.

In the curing step A, the irradiation time of the active energy rays on the ink applied on the substrate is, for example, 0.01 seconds to 120 seconds, preferably 0.1 seconds to 90 seconds.
As the irradiation conditions and the basic irradiation method, the irradiation conditions and the irradiation method disclosed in Japanese Patent Application Laid-Open No. 60-132767 can be similarly applied.
As the activation energy ray irradiation method, specifically, a method in which light sources are provided on both sides of the head unit including an ink ejection device and the head unit and the light source are scanned by a so-called shuttle method, or another light source that does not involve driving is used. A method of irradiating with active energy rays is preferable.
The irradiation of the active energy rays is preferably performed after a certain period of time (for example, 0.01 seconds to 120 seconds, preferably 0.01 seconds to 60 seconds) after the ink is landed and heat-dried.

-Curing step B-
The curing step B is a step of heating or irradiating the ink applied on the base material with infrared rays.
In the curing step B, the ink applied on the substrate is heated or irradiated with infrared rays to be heat-cured, so that the thermal cross-linking reaction (that is, the thermal polymerization reaction) of the specific particles in the ink proceeds. It is possible to improve the adhesion between the image and the substrate and the hardness of the image.

The heating means for heating is not particularly limited, and examples thereof include a heat drum, warm air, an infrared lamp, an infrared LED, an infrared heater, a heat oven, a heat plate, an infrared laser, and an infrared dryer. Among them, a light emitting diode having a maximum absorption wavelength in a wavelength of 0.8 μm to 1.5 μm or 2.0 μm to 3.5 μm and a light emitting wavelength in near infrared rays to far infrared rays in that the ink can be efficiently heat-cured. LED), a heater that emits near-infrared rays to far-infrared rays, a laser that has an oscillation wavelength in the near-infrared rays to far-infrared rays, or a dryer that emits near-infrared rays to far-infrared rays is preferable.

The heating temperature at the time of heating is preferably 40 ° C. or higher, more preferably 40 ° C. to 200 ° C., and even more preferably 100 ° C. to 180 ° C. The heating temperature refers to the temperature of the ink composition on the substrate, and can be measured by a thermograph using an infrared thermography apparatus H2640 (manufactured by Nippon Avionics Co., Ltd.).
The heating time can be appropriately set in consideration of the heating temperature, the composition of the ink, the printing speed, and the like.
Further, the curing step B, which is responsible for heat curing of the ink applied on the base material, may also serve as a heat drying step described later.

(Heat drying process)
If necessary, the image forming method may further include a heat-drying step after the applying step and before the curing step.
In the heat-drying step, it is preferable that the ink ejected onto the base material has an image fixed by evaporating water and, if necessary, an organic solvent used in combination by the heating means.
As the heating means, it is sufficient that water and, if necessary, an organic solvent used in combination can be dried. The heating means is not particularly limited, and examples thereof include a heat drum, hot air, an infrared lamp, a heat oven, and heat plate heating.
The heating temperature is preferably 40 ° C. or higher, more preferably 40 ° C. to 150 ° C., and even more preferably 40 ° C. to 80 ° C.
The heating time can be appropriately set in consideration of the composition of the ink and the printing speed.

The ink fixed by heating is further light-fixed by irradiating it with active energy rays in the irradiation step, if necessary. As described above, in the irradiation step, it is preferable to fix with UV light.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples. In the following, "parts" represents parts by mass unless otherwise specified. Moreover, "NCO compound" means an isocyanate compound.

[Synthesis of specific polymer]
The following polymer 1 was synthesized as a specific chain polymer according to the following reaction scheme.
Polymer 1 has a urethane bond formed by the reaction of IPDI (isophorone diisocyanate) with another raw material (diol compound).

IPDI (47.8 g), DMBA (2,2-bis (hydroxymethyl) butyric acid) (9.1 g), compound (2-13) (26.7 g), compound (a-19) (16) in a three-necked flask. .4 g) and ethyl acetate (100 g) were charged and heated to 70 ° C. To this, 0.2 g of Neostan U-600 (inorganic bismuth catalyst manufactured by Nitto Kasei Co., Ltd .; hereinafter also referred to as “U-600”) was added, and the mixture was stirred at 70 ° C. for 15 hours.
Next, isopropyl alcohol (IPA) (70.0 g) and ethyl acetate (63.3 g) were added thereto, and the mixture was stirred at 70 ° C. for 3 hours. After stirring for 3 hours, the reaction solution was allowed to cool to room temperature, and then the concentration was adjusted with ethyl acetate to obtain a 30% by mass solution of Polymer 1 (solvent was a mixed solution of ethyl acetate / isopropyl alcohol).
Polymer 1 had a weight average molecular weight (Mw) of 20000 and an anionic base value of 0.61 mmol / g. Further, the polymer 1 had a solubility of 1 g or less in 100 g of water at 25 ° C.

[Synthesis of specific hydrophilic group-containing compounds]
As a specific hydrophilic group-containing compound
DMBA / IPDI reaction product corresponding to the above-mentioned reaction product X1
D110 / Lysine reaction product corresponding to the above-mentioned reaction product X2,
D110 / Lysine underwater reaction product corresponding to the above-mentioned reaction product X3, and
The D116 underwater reaction products corresponding to the above-mentioned reaction products X4 were synthesized.

<Synthesis of DMBA / IPDI reaction product (DMBA / IPDI (molar ratio) = 1/3)>
DMBA / IPDI reaction products were synthesized according to the following reaction scheme.
The DMBA / IPDI reaction product has a urethane bond formed by the reaction of IPDI with DMBA. The terminal of the DMBA / IPDI reaction product is considered to be a primary amino group formed by the reaction of a trace amount of water mixed in ethyl acetate with an isocyanate group.

Specifically, in the synthesis of the polymer 1, the isocyanate compound (IPDI) and the diol compound (DMBA, compound (2-13), and compound (a-19)) are mixed with DMBA and IPDI (DMBA / IPDI (molar ratio) =. A 30% by mass solution of the DMBA / IPDI reaction product (solvent was ethyl acetate) was obtained in the same manner as in the synthesis of Polymer 1 except that it was replaced with 1/3) and isopropyl alcohol was not used.
The DMBA / IPDI reaction product had a number average molecular weight (Mn) of 1500 and an anionic base value of 1.2 mmol / g. The DMBA / IPDI reaction product had a solubility of more than 1 g in 100 g of water at 25 ° C.

<Synthesis of D110 / Lysine reaction product (D110 / Lysine (molar ratio) = 1/3)>
The D110 / Lysine reaction product was synthesized according to the following reaction scheme.
The D110 / Lysine reaction product has a urea bond formed by the reaction of D110 and Lysine, and has a urethane bond in the structure derived from D110.

First, Takenate (registered trademark) D-110N manufactured by Mitsui Chemicals, Inc. was prepared as a solution of a trifunctional isocyanate compound as a raw material.
Takenate D-110N is a 75 mass% ethyl acetate solution of an adduct (trifunctional isocyanate compound) of trimethylolpropane (TMP) and m-xylylene diisocyanate (XDI). Hereinafter, the trifunctional isocyanate compound which is a solid content in Takenate D-110N is referred to as "D110".
In addition, lysine manufactured by Tokyo Chemical Industry Co., Ltd. was prepared as the raw material Lysine.

In the synthesis of polymer 1, isocyanate compounds (IPDI) and diol compounds (DMBA, compound (2-13), and compound (a-19)) were used as Takenate D-110N and Lysine (D110 / Lysine (molar ratio)). A 30% by mass solution of the D110 / Lysine reaction product (solvent was ethyl acetate) was obtained in the same manner as in the synthesis of Polymer 1 except that it was replaced with / 3) and isopropyl alcohol was not used.
The D110 / Lysine reaction product had a number average molecular weight (Mn) of 1137 and an anionic base value of 2.6 mmol / g. The D110 / Lysine reaction product had a solubility of more than 1 g in 100 g of water at 25 ° C.

<Synthesis of D110 / Lysine underwater reaction product (D110 / Lysine (molar ratio) = 1/3)>
Ethyl acetate (40 parts) and Takenate D-110N (9.3 parts) were mixed and stirred for 15 minutes to obtain an oil phase component.
Distilled water (46 parts) and ricin (4.4 parts) manufactured by Tokyo Chemical Industry Co., Ltd. were mixed and stirred for 15 minutes to obtain an aqueous phase component.
The oil phase component and the aqueous phase component were mixed, and the obtained mixture was emulsified at 12000 rpm for 12 minutes using a homogenizer at room temperature to obtain an emulsion.
The obtained emulsion was added to distilled water, and the obtained liquid was stirred at room temperature for 30 minutes. Next, the stirred liquid was heated to 45 ° C. and stirred at 45 ° C. for 4 hours to distill off ethyl acetate from the above liquid.
The liquid from which ethyl acetate was distilled off was heated to 50 ° C., stirred for 24 hours while maintaining the liquid temperature at 50 ° C., and then diluted with distilled water to obtain a D110 / Lysine aqueous reaction product (D110 /). A 20% by mass aqueous solution of Lysine (molar ratio) = 1/3) was obtained.
The D110 / Lysine underwater reaction product had a number average molecular weight (Mn) of 4500 and an anionic base value of 2.2 mmol / g. The D110 / Lysine underwater reaction product had a solubility of more than 1 g in 100 g of water at 25 ° C.

The structure of the D110 / Lysine reaction product is considered to be a structure in which the following six structural units are randomly bound via urea bonds.

<Synthesis of D116 underwater reaction product>
First, Takenate (registered trademark) D-116N manufactured by Mitsui Chemicals, Inc. was prepared as a solution of the isocyanate compound as a raw material.
Takenate D-116N is a 50 mass% ethyl acetate solution of an adduct of trimethylolpropane (TMP), m-xylylene diisocyanate (XDI) and polyethylene glycol monomethyl ether (EO90).
Hereinafter, the above-mentioned adduct (solid content) in Takenate D-116N is referred to as "D116".
D116 is a nonionic group (specifically, the above-mentioned group (N1), R ¹ is an ethylene group, R ² is a methyl group, L is a single bond, and n is 90. ) Is introduced and the trifunctional isocyanate compound is mixed.
In D116, the content of nonionic groups is 50% by mass based on the whole D116.
The raw material of D116 is shown below.

Ethyl acetate (20 parts) and Takenate D-116N (20 parts) were mixed and stirred for 15 minutes to obtain an oil phase component.
The above oil phase component and distilled water (40 parts) were mixed, and the obtained mixture was emulsified at room temperature at 12000 rpm for 12 minutes using a homogenizer to obtain an emulsion.
The obtained emulsion was added to distilled water, and the obtained liquid was stirred at room temperature for 30 minutes. Next, the stirred liquid was heated to 45 ° C. and stirred at 45 ° C. for 4 hours to distill off ethyl acetate from the above liquid.
The liquid from which ethyl acetate was distilled off was heated to 50 ° C., stirred for 24 hours while maintaining the liquid temperature at 50 ° C., and then diluted with distilled water to obtain a 20% by mass aqueous solution of the D116 aqueous reaction product. Got
The D116 underwater reaction product had a number average molecular weight (Mn) of more than 100,000. The D116 underwater reaction product had a solubility of more than 1 g in 100 g of water at 25 ° C.

The structure of the D116 underwater reaction product is considered to be a structure in which the following six structural units are randomly bonded via urea bonds.

[Example 1]
<Preparation of aqueous dispersion of microcapsules (MC)>
An aqueous dispersion of microcapsules (MC) as specific particles was prepared as follows.
-Preparation of oil phase components-
Ethyl acetate (55 parts) and
Takenate (registered trademark) D-110N (11 parts as the amount of trifunctional isocyanate compound (D110 mentioned above) which is a solid content) manufactured by Mitsui Chemicals, Inc.
An ethyl acetate solution (amount described later) of the D110 / Lysine reaction product as a specific hydrophilic group-containing compound, and
With the polymerizable compound SR833S (hereinafter, also referred to as “S833”) (35 parts) manufactured by Sartmer Co., Ltd.
IGM Resins B. V. Photopolymerization initiator "Omnipol TX" (1.8 parts) manufactured by the company and
IGM Resins B. V. Photopolymerization initiator "Omnipol 9210" (3.5 parts) manufactured by the company and
With Rahn AG's photopolymerization initiator "Genopol AB-2" (1.8 parts),
Was mixed and stirred for 15 minutes to obtain an oil phase component.
The amount of the ethyl acetate solution of the D110 / Lysine reaction product was set so that the content of the D110 / Lysine reaction product (solid content) in the finally obtained ink was 1% by mass based on the total amount of the ink. ..

-Preparation of aqueous phase components-
Distilled water (50 parts), lysine (3.3 parts) manufactured by Tokyo Kasei Kogyo Co., Ltd. as a compound for introducing an anionic group (compound having an anionic group and an active hydrogen group), and hydroxide as a neutralizing agent. Aqueous phase components were prepared by mixing with sodium and stirring for 15 minutes.
The amount of sodium hydroxide used as the neutralizing agent was adjusted so that the degree of neutralization of the carboxy group in the D110 / Lysine reaction product and MC was 90%.
That is, in the aqueous dispersion of MC described later, both the D110 / Lysine reaction product and MC have a carboxy group and a salt thereof (Na salt) as hydrophilic groups.

The oil phase component and the aqueous phase component were mixed, and the obtained mixture was emulsified at 12000 rpm for 12 minutes using a homogenizer at room temperature to obtain an emulsion.
The obtained emulsion was added to distilled water, and the obtained liquid was stirred at room temperature for 30 minutes. Next, the stirred liquid was heated to 45 ° C. and stirred at 45 ° C. for 4 hours to distill off ethyl acetate from the above liquid.
The liquid from which ethyl acetate was distilled off was heated to 50 ° C., and the mixture was stirred for 24 hours while maintaining the liquid temperature at 50 ° C. to form microcapsules (MC) in the liquid.
Next, the liquid containing MC was diluted with distilled water so that the solid content was 20% by mass to obtain an aqueous dispersion of MC.

The obtained MC is a microcapsule containing a shell made of a crosslinked polymer having a urea bond and a three-dimensional crosslinked structure, and a core containing a polymerizable compound and three kinds of photopolymerization initiators.
In the aqueous dispersion of MC, a part or all of the above shell of MC interacts with the D110 / Lysine reaction product.
The MC shell had an anionic base value of 0.32 mmol / g. The MC shell had a solubility of 1 g or less in 100 g of water at 25 ° C.

The above S833 is a bifunctional polymerizable compound (polymerizable monomer), specifically, tricyclodecanedimethanol diacrylate.
Further, the photopolymerization initiator "Omnipol TX" is a multimerized thioxanthone.
In addition, the photopolymerization initiator "Genopol AB-2" is a polymerized 4-dimethylaminobenzoic acid ester.
The photopolymerization initiator "Omnipol 9210" is a mixture of polyethylene glycol di (β-4- [4- (2-dimethylamino-2-benzyl) butyroylphenyl] piperazine) propionate and ethoxylated pentaerythritol tetraacrylate. is there.

<Ink preparation>
Each component having the following composition was mixed to prepare an ink.

-Ink composition-
-Aqueous dispersion of MC: 50 parts-Pigment dispersion: 10 parts (Pro-jet Cyan APD1000 (manufactured by FUJIFILM Imaging Corollants), pigment concentration 14% by mass)
-Fluorine-based surfactant: 0.3 parts (DuPont, Capstone FS-31, solid content 25% by mass)
・ Glycerin… 5 copies ・ Water… 100 copies in total

<Evaluation>
The following evaluation was performed using the ink obtained above.
The results are shown in Table 1.

(Ink ejection property)
The above ink, which was stored at room temperature for less than 1 day after preparation, was ejected from the head of an inkjet printer (Roland DG, SP-300V) for 30 minutes, and then the ejection was stopped.
After a predetermined time (specifically, each time of 5 minutes, 8 minutes, and 10 minutes) has elapsed from the stop of ejection, the ink is ejected again from the head onto the substrate, and the ink is ejected from the head to 5 cm × 5 cm. A solid image was formed.
These images were visually observed to confirm the presence or absence of missing dots due to the occurrence of non-ejection nozzles, etc., and the ink ejection property was evaluated according to the following evaluation criteria.
In the following evaluation criteria, the one with the best ink ejection property is A.

-Evaluation criteria for dischargeability-
A: No missing dots were observed due to the occurrence of non-discharge nozzles, etc. even during the discharge evaluation 10 minutes after the stop of discharge, and a good image was obtained.
B: No missing dots were observed due to the occurrence of non-discharge nozzles during the discharge evaluation 8 minutes after the stop of discharge, and a good image was obtained, but the non-discharge nozzles were evaluated after 10 minutes. Was generated, and the occurrence of missing dots was observed.
C: During the discharge evaluation 5 minutes after the stop of discharge, no missing dots were observed due to the occurrence of non-discharge nozzles, etc., and a good image was obtained, but the non-discharge nozzles were evaluated after 8 minutes. Was generated, and the occurrence of missing dots was observed.
D: A non-discharge nozzle was generated during the discharge evaluation 5 minutes after the discharge was stopped, and the occurrence of missing dots was observed.

(Ink storage stability)
The above ink was sealed in a container and left at 60 ° C. for 2 weeks.
Using the ink after aging for 2 weeks, the same evaluation as the above-mentioned evaluation of ejection property was performed, and the storage stability of the ink was evaluated according to the same evaluation criteria.

[Examples 2 and 5-7]
The same operation as in Example 1 was carried out except that the content of the specific hydrophilic group-containing compound with respect to the total amount of ink was changed as shown in Table 1.
The results are shown in Table 1.

[Example 3]
The same operation as in Example 2 was carried out except that the compound having an anionic group and an active hydrogen group for forming the MC shell was changed from lysine to β-alanine (β-alanine having the following structure). ..
The results are shown in Table 1.

The MC shell in Example 3 had an anionic base value of 0.32 mmol / g. The MC shell in Example 3 had a solubility of 1 g or less in 100 g of water at 25 ° C.

[Example 4]
The same operation as in Example 2 was carried out except that the type and amount of the polymerizable compound contained in the MC core were changed as shown in Table 1.
The results are shown in Table 1.
Here, S399 is a polymerizable compound SR399E (dipentaerythritol pentaacrylate) manufactured by Sartmer.

[Examples 8 and 10 to 13]
The oil phase component does not contain the ethyl acetate solution of the D110 / Lysine reaction product, the aqueous phase component contains an aqueous solution of the D110 / Lysine underwater reaction product, and the content of the D110 / Lysine underwater reaction product with respect to the total amount of ink is shown in Table 1. The same operation as in Example 1 was carried out except that the amount was contained so as to be the amount shown in 1.
The results are shown in Table 1.

[Example 9]
The same operation as in Example 8 was carried out except that the compound having an anionic group and an active hydrogen group for forming the MC shell was changed from lysine to β-alanine.
The results are shown in Table 1.

[Examples 14 to 16]
The oil phase component did not contain the ethyl acetate solution of the D110 / Lysine reaction product, the aqueous phase component was an aqueous solution of the D116 underwater reaction product, and the content of the D116 underwater reaction product with respect to the total amount of ink was the amount shown in Table 1. The same operation as in Example 1 was carried out except that the mixture was contained so as to be.
The results are shown in Table 1.

[Comparative Example 1]
The same operation as in Example 1 was carried out except that the ethyl acetate solution of the D110 / Lysine reaction product was not contained in the oil phase component.
The results are shown in Table 1.

[Comparative Examples 2 and 3]
The same operation as in Example 1 was carried out except that the content of the specific hydrophilic group-containing compound with respect to the total amount of ink was changed as shown in Table 1.
The results are shown in Table 1.

[Comparative Example 4]
The oil phase component does not contain the ethyl acetate solution of the D110 / Lycine reaction product, and the aqueous phase component contains Uniox® M-4000 (registered trademark) M-4000 (manufactured by Nichiyu Co., Ltd., polyethylene glycol monomethyl ether, number average molecular weight). The same operation as in Example 1 except that 4000; hereinafter simply referred to as “M-4000”) was contained so that the solid content of M-4000 with respect to the total amount of ink was the amount shown in Table 1. Was done.
The results are shown in Table 1.
M-4000 is a nonionic group (specifically, the above-mentioned group (N1), R ¹ is an ethylene group, R ² is a methyl group, L is a single bond, and n is about 90. It is a compound having a group).

In each Example and each Comparative Example, the volume average dispersed particle size of MC was measured using the obtained aqueous dispersion of particles.
The volume average dispersed particle size of MC was in the range of 0.15 μm to 0.25 μm in all the examples.

As shown in Table 1, a shell (polymer) having a urethane bond and / or a urea bond is contained, and an MC having a polymerizable group is contained, and the bond U (that is, urethane bond, urea bond, thiourethane bond, and thiourea bond) is contained. The ink of Examples 1 to 16 containing 0.01 to 1% by mass of a specific hydrophilic group-containing compound having an anionic group or a nonionic group and containing at least one selected from the group consisting of Is the ink of Comparative Example 1 containing no specific hydrophilic group-containing compound, the inks of Comparative Examples 2 and 3 in which the content of the specific hydrophilic group-containing compound is more than 1% by mass with respect to the total amount of the ink, and the bonded urethane. Compared with the ink of Comparative Example 4 containing the comparative compound which does not have the above, the ejection property was excellent, and the storage stability was also excellent.

From the comparison between Example 1 and Example 8, it can be seen that when the number average molecular weight of the specific hydrophilic group-containing compound is 2000 or more (Example 8), the storage stability of the ink is further improved.
From the comparison between Examples 1 to 13 and Examples 14 to 16, when the number average molecular weight of the specific hydrophilic group-containing compound is 50,000 or less (Examples 1 to 13), the ink ejection property and storage stability of the ink are stable. Can be seen to improve further.
Further, from the comparison between Examples 1 to 13 and Examples 14 to 16, at least one hydrophilic group contained in the specific polymer contained in the specific particles and at least one hydrophilic group contained in the specific hydrophilic group-containing compound. It can be seen that when the seed and the group are of the same type (Examples 1 to 13), the ejection property and the storage stability of the ink are further improved.

From the comparison between Example 9 and Example 10, the specific polymer and the specific hydrophilic group-containing compound contained in the specific particles have a structure derived from the same type of bifunctional isocyanate compound (specifically, in XDI present in D110). When it has a structure derived from the same type of compound (specifically, lysine) having an anionic group and an active hydrogen group (specifically, lysine), the storage stability of the ink is further improved. You can see that it does.

[Example 101]
<Preparation of aqueous dispersion of specific particles containing specific linear polymer>
An aqueous dispersion of specific particles containing the specific linear polymer was prepared as follows.

-Preparation of oil phase components-
With ethyl acetate,
A 30 mass% solution of polymer 1 (51.5 parts as the amount of polymer 1) and
An ethyl acetate solution (amount described later) of the DMBA / IPDI reaction product as a specific hydrophilic group-containing compound, and
With the above-mentioned S833 (17.5 parts) as a polymerizable compound,
With the above-mentioned S399 (17.5 parts) as a polymerizable compound,
With the above-mentioned "Omnipol TX" (1.8 parts) as a photopolymerization initiator,
With the above-mentioned "Omnipol 9210" (3.5 parts) as a photopolymerization initiator,
With the above-mentioned "Genopol AB-2" (1.8 parts) as a photopolymerization initiator,
Was mixed and stirred for 15 minutes to obtain 44 g of an oil phase component having a solid content of 36% by mass.
The amount of the ethyl acetate solution of the DMBA / IPDI reaction product is such that the content of the DMBA / IPDI reaction product (solid content) in the finally obtained ink is 0.5% by mass with respect to the total amount of the ink. And said.

-Preparation of aqueous phase components-
Distilled water (45 parts) and sodium hydroxide as a neutralizing agent were mixed and stirred for 15 minutes to prepare an aqueous phase component.
The amount of sodium hydroxide used as the neutralizing agent was adjusted so that the degree of neutralization was 90% in the produced particles.

The oil phase component and the aqueous phase component were mixed, and the obtained mixture was emulsified at 12000 rpm for 10 minutes using a homogenizer at room temperature to obtain an emulsion. The obtained emulsion was added to distilled water (25 parts), and the obtained liquid was stirred at room temperature for 30 minutes. Next, the liquid was heated to 50 ° C. and stirred at 50 ° C. for 3 hours to distill off ethyl acetate from the liquid.
The liquid from which ethyl acetate had been distilled off was further stirred at 50 ° C. for 24 hours to form particles in the liquid.
Next, the liquid containing the particles was diluted with distilled water so that the solid content was 20% by mass to obtain an aqueous dispersion of the particles.

The formed particles are, in detail, particles containing the polymer 1, which is a specific linear polymer having a urethane bond, the above-mentioned two kinds of polymerizable compounds, and the above-mentioned three kinds of photopolymerization initiators.

The volume average dispersed particle size of the particles was measured using the obtained aqueous dispersion of the particles.
The volume average dispersed particle size of the particles was in the range of 0.15 μm to 0.25 μm.

<Ink preparation>
Each component having the following composition was mixed to prepare an ink.

-Ink composition-
-Aqueous dispersion of the above particles ... 50 parts-Pigment dispersion (Pro-jet Cyan APD1000 (manufactured by FUJIFILM Imaging Corollants), pigment concentration 14% by mass) ... 10 parts-Fluorosurfactant (DuPont, Capstone FS) -31, solid content 25% by mass) ... 0.3 parts, glycerin ... 5 parts, water ... Total remaining amount of 100 parts

<Evaluation>
Using the ink obtained above, the same evaluation as in Example 2 was performed.
The results are shown in Table 2.

As shown in Table 2, the total amount of the ink contains a specific hydrophilic group-containing compound containing a specific chain polymer having a urethane bond and / or a urea bond and a specific particle containing a polymerizable compound, and containing a bond U and having an anionic group. The ink of Example 101 containing 0.01 to 1% by mass based on the above was excellent in ejection property and also excellent in storage stability, as in Example 2 described above.

[Example 201] (Thermal polymerization ink)
As Example 201, an example using a heat-polymerized ink containing specific particles containing a specific linear polymer is shown.

<Synthesis of specific polymer>
The following polymer 2 was synthesized as a specific chain polymer according to the following reaction scheme.
The following polymer 2 has a structure in which a structural unit derived from IPDI and another structural unit are bonded to form a urethane bond.

IPDI (34.5 g), DMBA (9.1 g), compound (2-13) (56.4 g), and ethyl acetate (100 g) were placed in a three-necked flask and heated to 70 ° C. To this, 0.2 g of Neostan U-600 (inorganic bismuth catalyst manufactured by Nitto Kasei Co., Ltd .; hereinafter also referred to as “U-600”) was added, and the mixture was stirred at 70 ° C. for 15 hours.
Next, isopropyl alcohol (IPA) (70.0 g) and ethyl acetate (63.3 g) were added thereto, and the mixture was stirred at 70 ° C. for 3 hours. After stirring for 3 hours, the reaction solution was allowed to cool to room temperature, and then the concentration was adjusted with ethyl acetate to obtain a 30% by mass solution of Polymer 2 (solvent was a mixed solution of ethyl acetate / isopropyl alcohol).
Polymer 2 had a weight average molecular weight (Mw) of 20000 and an anionic base value of 0.61 mmol / g. Further, the polymer 2 had a solubility of 1 g or less in 100 g of water at 25 ° C.

<Preparation of aqueous dispersion, preparation of ink, evaluation>
In Example 101, the polymerizable compound and the photopolymerization initiator were distilled off under reduced pressure of propylene glycol monomethyl ether under the condition of 60 ° C. and 2.67 kPa (20 torr). Trixene ^TM BI7982 (thermally polymerizable monomer; block isocyanate; Baxenden). The same operation as in Example 101 was performed except that the mixture was changed to Chemicals) (hereinafter, also referred to as “B7882”; the amount is as shown in Table 3) and the polymer 1 was changed to the same amount of polymer 2. ..
The results are shown in Table 3.

[Example 202]
^{B7982 is EPICLON TM} 840 (DIC; hereinafter also referred to as “E840”; the amount is as shown in Table 3) which is a thermosetting oligomer having an epoxy group, and 2-methylimidazole (hereinafter, which is a thermosetting accelerator) which is a thermosetting accelerator. The same operation as in Example 201 was performed except that the amount was changed to “2MI”; the amount is as shown in Table 3).
The results are shown in Table 3.

The volume average dispersed particle size of the specific particles was measured using the aqueous dispersions of the specific particles in Examples 201 and 202. The volume average dispersed particle size of the specific particles was in the range of 0.15 μm to 0.25 μm.

As shown in Table 3, the same results as in Example 101 were obtained in Examples 201 and 202, which are heat-polymerized inks containing specific particles containing a specific chain polymer and a heat-polymerizable compound.

[Example 301] (Thermal polymerization ink, microcapsules)
Example 301 shows an example using a thermopolymerizable ink containing microcapsules including a shell made of a specific crosslinked polymer having a three-dimensional crosslinked structure and a core containing a thermopolymerizable compound.

<Preparation of aqueous dispersion, preparation of ink, evaluation>
In Example 2, the same operation as in Example 2 was carried out except that the polymerizable compound and the photopolymerization initiator were changed to B7982 (the amount is as shown in Table 4).
The results are shown in Table 4.

[Example 302]
The same operation as in Example 301 was carried out except that B7982 was changed to E840 (the amount is as shown in Table 4) and 2MI (the amount is as shown in Table 4) which is a thermosetting accelerator.
The results are shown in Table 4.

The volume average dispersed particle size of the specific particles was measured using the aqueous dispersions of the specific particles in Examples 301 and 302. The volume average dispersed particle size of the specific particles was in the range of 0.15 μm to 0.25 μm.

As shown in Table 4, it is also carried out in Examples 301 and 302 which are the heat polymerization type inks containing microcapsules including a shell made of a specific crosslinked polymer having a three-dimensional crosslinked structure and a core containing a thermopolymerizable compound. The same result as in Example 2 was obtained.

The disclosure of Japanese Patent Application No. 2017-080717, filed April 14, 2017, is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

Claims (12)

water and,
Particles containing a polymer having at least one of a urethane bond and a urea bond,
It has at least one bond selected from the group consisting of urethane bond, urea bond, thiourethane bond, and thiourea bond, and a hydrophilic group which is an anionic group, and has a solubility in 100 g of water at 25 ° C. of 1 g. Contains super-water-soluble hydrophilic group-containing compounds ,
The hydrophilic group-containing compound has a number average molecular weight of 1000 or more, and the content of the hydrophilic group-containing compound with respect to the total amount of the inkjet ink is 0.01% by mass to 1% by mass . The hydrophilic group-containing compound is
Reaction product X1, of a compound having a hydrophilic group and an active hydrogen group which are anionic groups, and a bifunctional isocyanate compound,
Reaction product X2 of a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group which are anionic groups,
A reaction product X3 of a trifunctional or higher functional isocyanate compound, a compound having a hydrophilic group and an active hydrogen group which are anionic groups, and water, or
Reaction product PX of a compound having three or more active hydrogen groups, a bifunctional isocyanate compound, a hydrophilic group which is an anionic group, and a compound having an active hydrogen group, and a reaction product X4 of water.
The inkjet ink according to claim 1. The inkjet ink according to claim 1 or 2, wherein the hydrophilic group-containing compound contains the following structural unit (X).

In the structural unit (X),
U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond,
R represents a divalent hydrocarbon group having 1 to 20 carbon atoms.
X ¹ represents a (n + m) -valued linking group.
W represents a hydrophilic group which is an anionic group and represents
n represents 0 or 1 and represents
m represents an integer of 2 to 6 and represents
(N + m) is an integer of 3 to 6 and
* Indicates the bond position with the group (UW), the bond position with the primary amino group, or the bond position with other structural units via urethane bond, urea bond, thiourethane bond, or thiourea bond. ..
In the base (UW),
U represents a urethane bond, a urea bond, a thiourethane bond, or a thiourea bond,
W represents a hydrophilic group which is an anionic group and represents
L represents a single bond or a divalent linking group.
* Represents the connection position with the structural unit (X). The inkjet ink according to any one of claims 1 to 3, wherein the hydrophilic group contained in the hydrophilic group-containing compound is at least one of a carboxy group and a salt of the carboxy group. The invention according to any one of claims 1 to 4, wherein the polymer contained in the particles further has a hydrophilic group which is at least one selected from the group consisting of an anionic group and a nonionic group. Inkjet ink. The inkjet ink according to claim 5, wherein at least one of the hydrophilic groups contained in the polymer and the hydrophilic group contained in the hydrophilic group-containing compound are the same group. The polymer and the hydrophilic group-containing compound contained in the particles are
It has a structure derived from the same type of bifunctional isocyanate compound and has a structure.
The inkjet ink according to any one of claims 1 to 6, which has a structure derived from the same type of compound having a hydrophilic group as an anionic group and an active hydrogen group. The inkjet ink according to any one of claims 1 to 7, wherein the hydrophilic group-containing compound has a number average molecular weight of 2000 to 50,000. The inkjet ink according to any one of claims 1 to 8, wherein the particles have a polymerizable group. The method for producing an inkjet ink according to any one of claims 1 to 9.
The hydrophilic group-containing compound
Reaction product X1, of a compound having a hydrophilic group and an active hydrogen group which are anionic groups, and a bifunctional isocyanate compound,
Reaction product X2 of a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group which are anionic groups,
A reaction product X3 of a trifunctional or higher functional isocyanate compound, a compound having a hydrophilic group and an active hydrogen group which are anionic groups, and water, or
It is a reaction product X4 of a reaction product PX of a compound having three or more active hydrogen groups, a bifunctional isocyanate compound, a hydrophilic group which is an anionic group, and a compound having an active hydrogen group, and water.
The particles are formed by mixing and emulsifying an oil phase component containing an organic solvent and the polymer, or an oil phase component containing an organic solvent and a trifunctional or higher functional isocyanate compound, and an aqueous phase component containing water. Have a process to
When the hydrophilic group-containing compound is the reaction product X1 or the reaction product X2, the oil phase component contains the hydrophilic group-containing compound.
A method for producing an inkjet ink in which the aqueous phase component contains the hydrophilic group-containing compound when the hydrophilic group-containing compound is the reaction product X3 or the reaction product X4. An image forming method including a step of applying the inkjet ink according to any one of claims 1 to 9 onto a substrate. water and,
Particles containing a polymer having at least one of a urethane bond and a urea bond,
It has at least one bond selected from the group consisting of urethane bond, urea bond, thiourethane bond, and thiourea bond, and a hydrophilic group which is an anionic group, and has a number average molecular weight of 1000 or more. Hydrophilic group-containing compounds having a content of 0.01% by mass to 1% by mass based on the total amount of the inkjet ink.
Contains,
The hydrophilic group-containing compound is
Reaction product X1, of a compound having a hydrophilic group and an active hydrogen group which are anionic groups, and a bifunctional isocyanate compound,
A reaction product X2 of a trifunctional or higher functional isocyanate compound and a compound having a hydrophilic group and an active hydrogen group, which are anionic groups, or
An inkjet ink which is a reaction product X3 of a trifunctional or higher functional isocyanate compound, a compound having a hydrophilic group and an active hydrogen group which are anionic groups, and water.