JP2019099689A - Inkjet ink - Google Patents

Abstract

To provide an inkjet ink that can suppress fluctuations in image gloss and dot diameter during high-temperature storage.SOLUTION: The inkjet ink contains a violet pigment having a dioxane structure, a polymer dispersant containing a basic group, a gelator, and a compound having a structure represented by general formula (I): [X]-(Y)[where X has a structure represented by general formula (I-A). Y is one of a sulfonic acid group or a carboxy group, Y may be present as a substituent substituting for a hydrogen atom in the ring of general formula (I-A), or R, Ror R. m is an integer of 1-4] [where R, Rand Rindependently represent one of a hydrogen atom, a halogen atom, an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkoxy group, a hydroxy group, an unsubstituted or substituted amino group, an unsubstituted or substituted aryl group].SELECTED DRAWING: None

Description

  The present invention relates to an inkjet ink, and more particularly to an inkjet ink capable of suppressing image gloss fluctuation and dot diameter fluctuation during high temperature storage.

  The inkjet recording method is used in various printing fields because an image can be formed easily and inexpensively. In the inkjet recording method, a suitable combination of inks is selected from yellow ink, magenta ink, cyan ink and black ink according to the color to be formed, and the selected ink is over-printed to obtain a full color image. It can be formed. In addition, in order to be able to cover the color gamut indicated by the Pantone (registered trademark) color sample book, a method for expanding the color gamut using a violet ink, an orange ink and a green ink as special colors is implemented. .

As a method of enhancing the pinning property of the inkjet ink used in the inkjet recording system, the addition of a gelling agent has been studied. That is, it has been studied to suppress the coalescence of dots by discharging an ink droplet in a liquid state at high temperature and causing the ink droplet to land on a recording medium at the same time as the ink droplet is cooled and gelated.
As such an ink jet ink, for example, Patent Document 1 discloses an ink jet ink containing a dioxazine structure violet pigment, a comb block copolymer having a tertiary amine group, a highly polar monomer and a gelling agent.
Patent Document 2 discloses, as a pigment dispersant, dispersants of a specific structure optimized for cyan pigments, magenta pigments and yellow pigments.

It is known that violet pigments contained in violet inks, particularly violet pigments having a dioxazine skeleton, have an inert pigment surface and low dispersibility. Therefore, it is difficult to maintain the dispersibility of the pigment in the ink because the polymer dispersant alone does not adsorb well to the pigment surface.
On the other hand, when the ink contains a gelling agent, the ink gelates due to the crystallization of the gelling agent when it lands on the recording medium and is cooled, so the pinning properties of the ink become high, and the desired image gloss and dot diameter can get.
However, if the pigment dispersion stability at high temperature storage is insufficient, the pigment surface and the gelling agent tend to interact with each other, and the amount of the gelling agent that can be crystallized decreases, so the obtained image gloss and dot diameter become There was a problem of fluctuating.

In Patent Document 1 described above, the use of a polymer dispersant having a specific structure is considered to improve particle size fluctuation and ejection stability due to ink storage. However, in dispersion | distribution only by a polymeric dispersing agent, suppression of the interaction of a violet pigment and a gelatinizer is inadequate, and the further suppression of the glossiness and dot diameter fluctuation | variation in high temperature storage is desired.
In Patent Document 2 above, it is said that the aqueous dispersion using a specific dispersant improves viscosity increase, color stain and weatherability, but a dispersant with a structure optimized for cyan pigment, magenta pigment and yellow pigment. The effect of improving the stability of the ink containing the violet pigment and the gelling agent at high temperature storage was unknown.

JP, 2016-141767, A JP, 2016-108520, A

  The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide an ink jet ink capable of suppressing image gloss fluctuation and dot diameter fluctuation during high temperature storage.

In the process of examining the cause of the above problems and the like in order to solve the above problems, the inventor of the present invention is an inkjet ink containing a violet pigment having a dioxane structure, a polymer dispersant containing a basic group, and a gelling agent, By using the compound of the general formula (I) having an anthraquinone structure, the compound of the general formula (I) exhibits high affinity with the condensed ring in the dioxazine structure of the violet pigment, and By strongly adsorbing the acidic group in the compound and the basic group in the polymer dispersant, the dispersion stability under high temperature storage is improved, and the interaction between the pigment and the gelling agent can be effectively suppressed. The present invention has been found to be able to suppress the decrease in the amount of gelling agent that can be crystallized.
That is, the above-mentioned subject concerning the present invention is solved by the following means.

〔式中、Ｒ_１、Ｒ_２及びＲ_３は、それぞれ独立に、水素原子、ハロゲン原子、無置換又は置換のアルキル基、無置換又は置換のアルコキシ基、ヒドロキシ基、無置換又は置換のアミノ基、無置換又は置換のアリール基のいずれかを表す。〕 1. An inkjet ink comprising a violet pigment having a dioxane structure, a polymer dispersant containing a basic group, and a gelling agent,
An inkjet ink comprising a compound having a structure represented by the following general formula (I).
General formula (I): [X]-(Y) _m
[Wherein, X has a structure represented by the following general formula (IA). Y is either a sulfonic acid group or a carboxy group, and Y can be present as a substitute for a hydrogen atom in a ring of the following general formula (IA), R ₁ , R ₂ or R ₃ . m represents an integer of 1 to 4; ]

[Wherein, R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, a halogen atom, an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkoxy group, a hydroxy group, an unsubstituted or substituted amino group Or represents an unsubstituted or substituted aryl group. ]

〔式中、Ｒ_４は、水素原子、無置換又は置換のアルキル基、無置換又は置換のアリール基のいずれかを表す。なお、前記一般式（Ｉ）におけるＹは、前記一般式（II）〜（IV）で表される構造の環又はＲ_４中の、水素原子に代わる置換基として存在し得る。〕 2. The inkjet ink according to claim 1, wherein the general formula (IA) has a structure of any one of the structures represented by the following general formulas (II) to (IV).

[Wherein, R ₄ represents a hydrogen atom, an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group. In the general formula (I), Y may be present as a substituent in place of a hydrogen atom in the ring of the structure represented by the general formulas (II) to (IV) or R ₄ . ]

  3. Content of the compound represented by the said General formula (I) is in the range of 2.0-10.0 mass% with respect to the said violet pigment, The 1st term or 2nd term characterized by the above-mentioned Inkjet ink as described.

  4. The inkjet ink according to any one of Claims 1 to 3, wherein the polymer dispersant has an amine value of 10 to 100 mg KOH / g.

  5. The inkjet ink according to any one of Claims 1 to 3, wherein the polymer dispersant has an amine value of 30 to 80 mg KOH / g.

  6. Content of the said polymeric dispersing agent exists in the range of 30.0-70.0 mass% with respect to the said violet pigment, The claim | item 1 to 5 characterized by the above-mentioned Inkjet ink as described.

7. 7. Any one of items 1 to 6, wherein the gelling agent contains at least one selected from the group consisting of compounds having structures represented by the following general formulas (G1) and (G2) The inkjet ink according to any one of the preceding claims.
General Formula _{(G1): R 11 -CO-} R 12
Formula _{(G2): R 13 -COO-} R 14
[In formula, R < ₁₁ > -R < ₁₄ > respectively independently represents the alkyl group which may contain a linear part in the range of C12-C26, and may also contain branch. ]

  8. The content of the gelling agent is in the range of 1.0 to 7.0% by mass with respect to the total mass of the ink, as described in any one of the items 1 to 7, Inkjet ink.

  9. The violet pigment is at least C.I. I. Pigment Violet 23 or C.I. I. 9. The inkjet ink according to any one of items 1 to 8, comprising any of CI Pigment Violet 37.

  10. The inkjet ink according to any one of Items 1 to 9, wherein the average dispersed particle size of the violet pigment is in the range of 50 to 150 nm.

  11. The inkjet ink according to any one of Items 1 to 9, wherein the average dispersed particle size of the violet pigment is in the range of 80 to 130 nm.

  12. 12. The inkjet ink according to any one of items 1 to 11, wherein the inkjet ink is an actinic radiation curable inkjet ink containing a photopolymerizable compound and a photopolymerization initiator.

According to the above-mentioned means of the present invention, it is possible to provide an ink jet ink capable of suppressing image gloss fluctuation and dot diameter fluctuation during high temperature storage.
The mechanism for expressing the effect of the present invention or the mechanism of action is not clear but is presumed as follows.
In the compound of the general formula (I), the compound of the general formula (I) has high affinity to the condensed ring in the dioxazine structure of the violet pigment and thereby the elimination from the pigment is suppressed. By strongly adsorbing the acidic group in the polymer dispersant and the basic group in the polymer dispersant, the dispersion stability under high temperature storage is improved, the interaction between the pigment and the gelling agent is effectively suppressed, and the crystal is crystallized. The amount of gelling agent that can be reduced can be suppressed. Therefore, it is presumed that, even at high temperature storage of the ink, the crystallization of the gelling agent causes the ink to gel, and image gloss fluctuation and dot diameter fluctuation can be suppressed.

  The inkjet ink of the present invention is an inkjet ink containing a violet pigment having a dioxane structure, a polymer dispersant containing a basic group, and a gelling agent, and a compound having a structure represented by the above general formula (I) It is characterized by containing. This feature is a technical feature common to or corresponding to the following embodiments.

  In an embodiment of the present invention, in the dioxazine structure of the violet pigment, it is preferred that the general formula (IA) has a structure of any one of the structures represented by the general formulas (II) to (IV) It is preferable at the point which can suppress detachment | desorption from a pigment by showing the fused ring and especially high affinity.

  Moreover, the dispersion stability at high temperature storage is good that the content of the compound represented by the general formula (I) is in the range of 2.0 to 10.0% by mass with respect to the violet pigment. This is preferable in that the gloss fluctuation and the dot diameter fluctuation can be suppressed.

  In addition, the polymer dispersant has an amine value of 10 to 100 mg KOH / g, so that the acid-base interaction with the acidic group contained in the compound of the general formula (I) is strong and the dispersibility is good. It is preferable from the viewpoint of suppressing the increase of the average dispersed particle diameter. In particular, the amine value is preferably in the range of 30 to 80 mg KOH / g.

  In addition, when the content of the polymer dispersant is in the range of 30.0% to 70.0% by mass with respect to the violet pigment, the interaction between the pigment and the gelling agent is effectively suppressed. It is preferable in that the gloss fluctuation and the dot diameter fluctuation under high temperature storage can be further suppressed.

  Further, it is preferable that the gelling agent contains at least one selected from the group consisting of compounds having the structures represented by the general formulas (G1) and (G2) from the viewpoint of further enhancing the pinning property.

  In addition, when the content of the gelling agent is in the range of 1.0 to 7.0% by mass with respect to the total mass of the ink, the gloss of the image can be suppressed and the pinning property can be enhanced. Preferred.

  In addition, the violet pigment is at least C.I. I. Pigment Violet 23 or C.I. I. It is preferable to include any of Pigment Violet 37 in that a desired color gamut can be obtained.

  The average dispersed particle diameter of the violet pigment is preferably in the range of 50 to 150 nm in that the dischargeability from the inkjet head can be further enhanced, and it is particularly preferably in the range of 80 to 130 nm. preferable.

  Further, the inkjet ink is suitably used for an actinic radiation curable inkjet ink containing a photopolymerizable compound and a photopolymerization initiator.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described. In the present application, “to” is used in the meaning including the numerical values described before and after that as the lower limit value and the upper limit value.

〔式中、Ｒ_１、Ｒ_２及びＲ_３は、それぞれ独立に、水素原子、ハロゲン原子、無置換又は置換のアルキル基、無置換又は置換のアルコキシ基、ヒドロキシ基、無置換又は置換のアミノ基、無置換又は置換のアリール基のいずれかを表す。〕 1. Ink Jet Ink The ink jet ink of the present invention is an ink jet ink containing a violet pigment having a dioxane structure, a polymer dispersant containing a basic group, and a gelling agent, and having a structure represented by the following general formula (I) It is characterized in that it contains a compound which it has (hereinafter, also simply referred to as "the compound of the general formula (I)").
General formula (I): [X]-(Y) _m
[Wherein, X has a structure represented by the following general formula (IA). Y is either a sulfonic acid group or a carboxy group, and Y can be present as a substitute for a hydrogen atom in a ring of the following general formula (IA), R ₁ , R ₂ or R ₃ . m represents an integer of 1 to 4; ]

[Wherein, R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, a halogen atom, an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkoxy group, a hydroxy group, an unsubstituted or substituted amino group Or represents an unsubstituted or substituted aryl group. ]

<Compound Having a Structure Represented by General Formula (I)>
In the general formula (I), Y is either a sulfonic acid group or a carboxy group, and Y is a hydrogen atom in the ring, R ₁ , R ₂ or R _{3 of the} general formula (IA) May be present as a substitute for
The sulfonic acid group is preferably a sulfonic acid or a sulfonic acid salt. The carboxy group is preferably a carboxylic acid or a carboxylate. Furthermore, sulfonic acids or carboxylic acids are more preferred. In the case of salts, amine salts such as quaternary ammonium salts, alkali metal salts such as Li, Na and K, and alkaline earth metal salts such as Ca, Ba and Al are preferable.
m represents an integer of 1 to 4;

In the general formula (IA), R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, a halogen atom, an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkoxy group, a hydroxy group, no It represents either a substituted or substituted amino group or an unsubstituted or substituted aryl group.
As a substituent, although a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group, an amino group, an aryl group etc. are mentioned, it is not specifically limited.

  Since the anthraquinone structure contained in the compound of the general formula (I) exhibits high affinity with the condensed ring in the dioxazine structure of the violet pigment, the detachment from the pigment is suppressed. Furthermore, the acid group contained in the compound of the general formula (I) and the basic group contained in the polymer dispersant exhibit strong acid-base interaction, whereby the dispersion stability under high temperature storage is improved. The interaction between the pigment and the gelling agent can be effectively suppressed, and the amount of the gelling agent that can be crystallized can be suppressed from decreasing.

〔式中、Ｒ_４は、水素原子、無置換又は置換のアルキル基、無置換又は置換のアリール基のいずれかを表す。なお、前記一般式（Ｉ）におけるＹは、前記一般式（II）〜（IV）で表される構造の環又はＲ_４中の、水素原子に代わる置換基として存在し得る。〕 It is preferable that the compound which has a structure represented by said general formula (IA) has a structure of any one of the structure represented by the following general formula (II)-(IV).

[Wherein, R ₄ represents a hydrogen atom, an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group. In the general formula (I), Y may be present as a substituent in place of a hydrogen atom in the ring of the structure represented by the general formulas (II) to (IV) or R ₄ . ]

In the general formulas (II) to (IV), R ₄ represents a hydrogen atom, an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group.
As a substituent, although a halogen atom, an alkyl group, an alkoxy group, a hydroxyl group, an amino group, an aryl group etc. are mentioned, it is not specifically limited.
Since the structures of the general formulas (II) to (IV) show particularly high affinity with the condensed ring in the dioxazine structure of the violet pigment, the detachment from the pigment is suppressed.

The compound which has a structure represented by said general formula (I) is illustrated below.

1-1. Process for producing a compound having a structure represented by the general formula (IA) The compound having a structure represented by the above general formula (IA) can be produced by a generally known method .
The sulfonic acid group or carboxy group in the general formula (I) can be produced by sulfonation or carboxylation of a compound having a structure represented by the general formula (IA).

The outline of the production method will be described using sulfonation as a specific example.
First, a compound having a structure represented by General Formula (IA) is charged into chlorosulfonic acid, fuming sulfuric acid and the like, and sulfonation is performed by heating. Thereafter, the compound of general formula (I) can be obtained by washing out the impurities.
Further, in order to conduct sulfonation efficiently, it is preferable to add a catalyst such as boronic acid, phosphorus pentoxide, acetic anhydride or the like.
The advantage of this method is that the sulfonation can be controlled. If the sulfonation can be controlled, it is easy to stabilize the quality.

Next, the outline of the production method will be described by using carboxylation as a specific example.
First, a compound having a structure represented by the general formula (IA) is introduced into chloroform, carbon disulfide or the like, aluminum chloride or copper chloride is added, oxalyl chloride is added, and then water is added to perform carboxylation. Do. Thereafter, the compound of general formula (I) can be obtained by washing out the impurities.
The advantage of this method is that the carboxylation can be controlled. If the carboxylation can be controlled, it is easy to stabilize the quality.

The content of the compound of the general formula (I) is preferably in the range of 2.0 to 10.0% by mass with respect to the violet pigment. When the content of the compound of the general formula (I) is less than 2.0% by mass with respect to the violet pigment, the dispersion stability at high temperature storage is reduced, thereby increasing the interaction between the pigment and the gelling agent , Gloss fluctuation and dot diameter fluctuation tend to be large. When the content of the compound of the general formula (I) is more than 10.0% by mass with respect to the pigment, an excess of the compound of the general formula (I) which can not be adsorbed to the pigment causes gelation inhibition and the initial gloss Value, initial dot diameter will be large.
The content of the compound of the general formula (I) is more preferably in the range of 3.0 to 7.0% by mass with respect to the violet pigment. In the ink jet ink of the present invention, the compound of the general formula (I) may contain only one type, or two or more types.

1-2. Pigment The pigment according to the present invention contains a violet pigment having a dioxazine skeleton. The violet pigment having a dioxazine skeleton may be contained singly or in combination of two or more kinds in the inkjet ink of the present invention.
The content of the pigment may be in such a range that the color development of violet in the obtained image is sufficient and the viscosity of the ink can be discharged from the ink jet head. From the above viewpoint, for example, the content of the pigment is preferably in the range of 0.1 to 20% by mass with respect to the inkjet ink, and more preferably in the range of 0.4 to 10% by mass. preferable.

Examples of violet pigments having a dioxazine skeleton include C.I. I. Pigment Violet 23 (hereinafter abbreviated as PV23) and C.I. I. Pigment Violet 37 (hereinafter abbreviated as PV 37) is included.
Examples of commercial products of PV23 include Fastogen Super Violet LBP02, Fastogen Super Violet LBP03, Fastogen Super Violet LBP04 (all manufactured by DIC Corporation, "FASTOGEN" is a registered trademark of the company), Cromophtal Violet D5808 (manufactured by BASF Corporation), "Cromophtal" is a registered trademark of the company, Hostaperm Violet RL-NF, Hostaperm Violet P-RL, PV Fast Violet RL (manufactured by Clariant, "Hostaperm" is a registered trademark of the company).
Commercially available examples of PV37 include Cromophtal Violet D5808 (manufactured by BASF).
As violet pigments having a dioxazine skeleton, PV23 and PV37 are preferable, and PV23 is more preferable.

1-3. Polymeric Dispersant The polymer dispersant according to the present invention has a basic group.
The polymer dispersant having the basic group is directly adsorbed to the surface of the pigment, or indirectly adsorbed through the compound of the general formula (I) to enhance the dispersibility of the pigment. It can have a function. The polymer dispersant having a basic group may have any structure as long as it contains a basic group, but among them, it has good affinity with the violet pigment having a dioxazine skeleton and is included in the compound of the general formula (I) Preferred are comb-type block copolymers having a basic group, from the viewpoint of acid-base interaction with acidic groups to be used.

The comb block copolymer in the comb block copolymer having a basic group means graft polymerization on a linear polymer forming the main chain and each structural unit derived from a monomer constituting the linear main chain. Copolymers having different types of polymers.
As a side chain, a long chain polyoxyalkyl group (EO-PO copolymerized group) is preferable. Examples of comb block copolymers include those in which the main chain is an acrylic ester polymer and the side chains are long chain polyoxyalkyl groups (EO-PO copolymerized groups).
The basic group in the comb block copolymer having a basic group is preferably a quaternary, tertiary, secondary or primary amine group.

  The basic group of the comb block copolymer having a basic group can have a good affinity to the acidic group of the compound of the general formula (I). Therefore, the comb block copolymer having a basic group hardly dissociates from the compound of the general formula (I) even at around 85 ° C. at which the ink is ejected. Further, in the comb-type block copolymer having a basic group, since the graft-polymerized side chain causes steric hindrance, aggregation of the pigments can be suppressed. Since the pigment has a small primary particle diameter of 50 nm or less, the interaction between particles is strong and has a property of being easily aggregated. Therefore, the improvement of dispersibility by the comb block copolymer is particularly remarkable in the ink containing the pigment having such a small particle size. By the above-mentioned action, the dispersion stability under high temperature storage is improved, the interaction between the pigment and the gelling agent can be effectively suppressed, and the reduction of the amount of the gelling agent capable of crystallization can be suppressed.

  Commercially available examples of polymer dispersants containing a basic group include BYPER's DISPERBYK-109, 161, 168, 180, 2013, 2155, BYKJET-9150 and BYKJET-9151; and BASF's EFKA-4431. And PB-821, 822, 824 manufactured by Ajinomoto Fine Techno Co .; Solsperse 24000GR, 32000, 39000, 71000 and J-200 manufactured by Lubrizol. “DISPERBYK” and “BYKJET” are registered trademarks of BYK, “EFKA” is a registered trademark of BASF, and “Solsperse” is a registered trademark of Lubrizol.

The amine value of the polymer dispersant is preferably in the range of 10 to 100 mg KOH / g. When the amine value of the polymer dispersant is less than 10 mg KOH / g, the acid-base interaction with the acidic group contained in the compound of the general formula (I) is weak, so the dispersibility is reduced and the average dispersed particle size becomes large. In addition, the interaction between the pigment and the gelling agent under high temperature storage is increased. When the amine value of the polymer dispersant is greater than 100 mg KOH / g, the affinity to the dispersion medium is reduced, and the average dispersion particle size is increased.
More preferably, the amine value is in the range of 30 to 80 mg KOH / g. An amine value can be measured according to JIS K 7237.

The content of the polymer dispersant is preferably in the range of 30.0 to 70.0% by mass with respect to the total mass of the pigment. When the content of the polymer dispersant is 30.0% by mass or more with respect to the pigment, not only the pigment may be less likely to cause aggregation, but also the interaction between the pigment and the gelling agent may be effectively suppressed. Therefore, it is possible to further suppress the gloss fluctuation under high temperature storage and the dot diameter fluctuation. When the content of the polymer dispersant is more than 70.0% by mass with respect to the pigment, the extra polymer dispersant not contributing to the pigment dispersion causes gelation inhibition, and the initial gloss value and the initial dot diameter are large. turn into.
The content of the polymeric dispersant is more preferably in the range of 35 to 65% by mass with respect to the total mass of the pigment.
The polymer dispersant may be contained alone or in combination of two or more kinds in the ink jet ink of the present invention.

  Dispersion of the pigment and the polymer dispersant can be carried out by, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill or paint shaker.

1-4. Gelling Agent The inkjet ink of the present invention is a gel ink containing a gelling agent.
The gelling agent can temporarily fix (pin) ink droplets that have landed on the recording medium in a gel state. When the ink is pinned in a gel state, the wetting and spreading of the ink is suppressed and adjacent dots are less likely to be integrated, so that a higher definition image can be formed. In the inkjet ink of the present invention, only one type of gelling agent may be contained, or two or more types may be contained.

The content of the gelling agent is preferably in the range of 1.0 to 7.0% by mass with respect to the total mass of the ink. By setting the content of the gelling agent to 1.0% by mass or more, the gloss of the image can be suppressed and the pinning property of the ink can be enhanced. When the content of the gelling agent is more than 7.0% by mass, the deposition of the gelling agent on the image surface is increased, whereby the gloss is excessively lowered and the pinning property is also enhanced.
From the above viewpoint, the content of the gelling agent in the inkjet ink is preferably in the range of 1.0 to 7.0% by mass, and is in the range of 2.0 to 5.0% by mass. Is more preferred.

  In addition, from the following viewpoints, the gelling agent is preferably crystallized in the ink at a temperature equal to or lower than the gelling temperature of the ink. The gelation temperature is a temperature at which the gelling agent undergoes a phase transition from sol to gel when the solified or liquefied ink is cooled, and the viscosity of the ink suddenly changes. Specifically, a solified or liquefied ink is cooled while measuring its viscosity with a visco-elasticity measuring device (for example, MCR 300, manufactured by Physica), and the temperature at which the viscosity sharply rises is It can be at a gelling temperature.

When the gelling agent crystallizes in the ink, a structure may be formed in which an ink medium such as a solvent or a photopolymerizable compound is included in a three-dimensional space formed by the plate-shaped crystallized gelling agent. (Such a structure is called "card house structure" below).
When the card house structure is formed, since the liquid ink medium is held in the space, the ink droplets are less likely to spread and spread, and the ink pinning performance is further enhanced. When the pinning property of the ink is enhanced, it is difficult for the ink droplets landed on the recording medium to be united with each other, and an image with higher definition can be formed.
In order to form a card house structure, it is preferable that a solvent in the ink, an ink medium such as a photopolymerizable compound, and a gelling agent be compatible. On the other hand, if the solvent in the ink, the ink medium such as the photopolymerizable compound, and the gelling agent are phase-separated, it may be difficult to form a cardhouse structure.

  Examples of gelling agents suitable for forming a cardhouse structure by crystallization include ketone waxes, ester waxes, petroleum waxes, vegetable waxes, animal waxes, mineral waxes, hydrogenated castor oil, modified waxes, higher fatty acids Also included are fatty acids amides including higher alcohols, hydroxystearic acid, N-substituted fatty acid amides and special fatty acid amides, higher amines, esters of sucrose fatty acids, synthetic waxes, dibenzylidene sorbitol, dimer acids and dimer diols.

  Examples of the ketone wax include dilignoceryl ketone, dibehenyl ketone, distearyl ketone, dieicosyl ketone, dipalmityl ketone, dilauryl ketone, dimyristyl ketone, myristyl palmityl ketone and palmityl stearyl ketone Be

Examples of the above ester waxes include behenyl behenyl becohenate, icosyl icosylate, stearyl stearate, palmityl stearate, cetyl palmitate, myristyl myristate, cetyl myristate, mytilyl cellitate, stearyl stearate, oleyl palmitate, glycerin fatty acid Included are esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters and polyoxyethylene fatty acid esters.
Examples of the commercially available ester wax include the EMALEX series, manufactured by Nippon Emulsion Co., Ltd. (“EMALEX” is a registered trademark of the company), the Rikemar series and Poem series, and the Riken vitamin company (“Rikemar” and “Poem” Also includes the company's registered trademark).

Examples of the petroleum-based waxes include petroleum-based waxes including paraffin wax, microcrystalline wax and petrolactam.
Examples of the above-mentioned vegetable waxes include candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, jojoba solid wax and jojoba ester.
Examples of the animal waxes include beeswax, lanolin and spermaceti.
Examples of the mineral waxes include montan wax and hydrogenated waxes.
Examples of the modified wax include montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives, 12-hydroxystearic acid derivatives and polyethylene wax derivatives.

Examples of the above-mentioned higher fatty acids include behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid and erucic acid.
Examples of the higher alcohols include stearyl alcohol and behenyl alcohol.
Examples of the hydroxystearic acid include 12-hydroxystearic acid.
Examples of the above fatty acid amides include lauric acid amide, stearic acid amide, behen acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide and 12-hydroxystearic acid amide.
Examples of commercial products of the above fatty acid amide include Diamid Y, Nikka Amide series, manufactured by Nippon Kasei Co., Ltd. ("Diamid", "Nikka Amide" is a registered trademark of the company), ITOWAX series, Ito Oil Co., Ltd., and FATTYAMID The series includes Kao Corporation.

Examples of the above N-substituted fatty acid amides include N-stearyl stearic acid amide and N-oleyl palmitic acid amide.
Examples of the above-mentioned special fatty acid amides include N, N'-ethylenebisstearylamide, N, N'-ethylenebis-12-hydroxystearylamide and N, N'-xylylene bisstearylamide.
Examples of the above-mentioned higher amines include dodecylamine, tetradecylamine and octadecylamine.

Examples of the esters of sucrose fatty acid include sucrose stearic acid and sucrose palmitic acid.
Examples of commercially available esters of sucrose fatty acid esters include Ryoto Sugar Ester Series, manufactured by Mitsubishi Chemical Foods ("Ryoto" is a registered trademark of the company).
Examples of the synthetic waxes include polyethylene waxes and alpha-olefin maleic anhydride copolymer waxes.
Examples of commercial products of the synthetic wax include UNILIN series, manufactured by Baker-Petrolite ("UNILIN" is a registered trademark of the company).

Examples of the above dibenzylidene sorbitol include 1,3: 2,4-bis-O-benzylidene-D-glucitol.
Examples of commercial products of dibenzylidene sorbitol include Gelol D, manufactured by Shin Nippon Rika Co., Ltd. ("Gelol" is a registered trademark of the company).
Examples of commercial products of the above dimer diol include PRIPROR series manufactured by CRODA ("PRIPR" is a registered trademark of the company).

Among these gelling agents, ketone waxes, ester waxes, higher fatty acids, higher alcohols and fatty acid amides are preferable from the viewpoint of enhancing the pinning property, and from the above viewpoints, ketones represented by the following general formula (G1) A wax and an ester wax represented by the following general formula (G2) are more preferable, and a ketone wax is preferable from the viewpoint of using it with the above-mentioned high polar photopolymerizable compound.
For the ketone wax represented by the following general formula (G1) and the ester wax represented by the following general formula (G2), only one type may be contained in the violet ink, and two or more types may be contained. May be Moreover, as for the ketone wax represented by the following general formula (G1) and the ester wax represented by the following general formula (G2), either one may be included in the violet ink, or both are included. It may be done.

General Formula _{(G1): R 11 -CO-} R 12
In General Formula (G1), R ₁₁ and R ₁₂ each represent a linear or branched hydrocarbon group having a carbon number of ₁₂ to 26.
Formula _{(G2): R 13 -COO-} R 14
In General Formula (G2), R ₁₃ and R ₁₄ each represent a linear or branched hydrocarbon group having a carbon number of 12 to 26.

The ketone wax represented by the general formula (G1) or the ester wax represented by the general formula (G2) is gelated because the number of carbon atoms of the linear or branched hydrocarbon group is 12 or more. The crystallinity of the agent is increased, and a sufficient space is created in the above card house structure. Therefore, the ink medium such as the solvent and the photopolymerizable compound is easily contained in the space, and the pinning property of the ink is further enhanced.
In addition, since the linear or branched hydrocarbon group has a carbon number of 26 or less, the melting point of the gelling agent does not increase excessively, and it is not necessary to heat the ink excessively when the ink is ejected. .
From the above viewpoint, it is particularly preferable that R ₁₁ and R ₁₂ or R ₁₃ and R _{14 be} a linear hydrocarbon group having 13 to 23 carbon atoms.
Also, from the viewpoint of increasing the gelation temperature of the ink and causing the ink to gel more rapidly after impact, carbon in which either R ₁₁ or R ₁₂ or R ₁₃ or R ₁₄ is saturated It is preferable that it is a hydrocarbon group having 11 to less than 23 atoms.
From the above viewpoint, it is more preferable that both of R ₁₁ and R ₁₂ or both of R ₁₃ and R ₁₄ be a saturated hydrocarbon group having 11 or more and less than 23 carbon atoms.

  Examples of ketone waxes represented by the above general formula (G1) include dilignoceryl ketone (number of carbons: 23 to 24), dibehenyl ketone (number of carbons: 21 to 22), and distearyl ketone (number of carbons: 17) 18), dieicosyl ketone (carbon number: 19 to 20), dipalmityl ketone (carbon number: 15 to 16), dimyristyl ketone (carbon number: 13 to 14), dilauryl ketone (carbon number: 11) -12), lauryl myristyl ketone (carbon number: 11-14), lauryl palmityl ketone (carbon number: 11-16), myristyl palmityl ketone (carbon number: 13-16), myristyl stearyl ketone (carbon number: 13) ~ 18), myristyl behenyl ketone (carbon number: 13 to 22), palmityl stearyl ketone (carbon number: 15 to 18), valmityl behenyl ketone (carbon) Number: 15-22) and stearyl behenyl ketone (carbon number: 17-22) are included. In addition, carbon number in the said parenthesis represents carbon number of each of two hydrocarbon groups divided | segmented by the carbonyl group.

  Examples of commercially available ketone wax represented by the general formula (G1) include 18-Pentatriacontanon, manufactured by Alfa Aeser, Hentriacontan-16-on, manufactured by Alfa Aeser, Kao Wax T-1, manufactured by Kao Corporation Be

  Examples of the fatty acid or ester wax represented by the general formula (G2) include behenyl behenate (number of carbons: 21 to 22), icososyl eicosanate (number of carbon: 19 to 20), stearyl stearate (number of carbons: 17) -18), palmityl stearate (carbon number: 17-16), lauryl stearate (carbon number: 17-12), cetyl palmitate (carbon number: 15-16), stearyl palmitate (carbon number: 15-18) ) Myristyl myristate (carbon number: 13-14), cetyl myristate (carbon number: 13-16), octyldodecyl myristate (carbon number: 13-20), stearyl oleate (carbon number: 17-18) , Stearyl erucate (carbon number: 21-18), stearyl linoleate (carbon number: 17-18), behenyl oleate (carbon number: 8-22) and linoleic acid arachidyl (carbon number: 17 to 20) are included. In addition, carbon number in the said parenthesis represents carbon number of each of two hydrocarbon groups divided | segmented by ester group.

Examples of commercial products of ester wax represented by the general formula (G2) include Unistar M-2222SL and Sparm Acetic, manufactured by NOF Corporation ("Unister" is a registered trademark of the company), EXEPEARL SS and EXEPEARL MY-M, Kao Products ("EXCEPEARL" is a registered trademark of the company, EMALEX CC-18 and EMALEX CC-10, made by Nippon Emulsion Co., Ltd. ("EMALEX" is a registered trademark of the company) and AMREPS PC, manufactured by Higher Alcohol Industry Co., Ltd. ("AMREPS" Includes the company's registered trademark).
Since these commercial products are often a mixture of two or more types, they may be separated and purified as necessary to be contained in the ink. Among these gelling agents, ketone waxes, ester waxes, higher fatty acids, higher alcohols and fatty acid amides are preferable from the viewpoint of further improving the pinning property.

1-5. Oil-based ink The ink-jet ink of the present invention is preferably an oil-based ink. The oil-based ink can contain a solvent, a vegetable oil, and an organic solvent.
Solvents constituting the oil-based ink of the present invention include aliphatic hydrocarbons such as octane, nonane, decane, dodecane, isooctane and isodecane, alicyclic hydrocarbons such as cyclohexane, cyclooctane and cyclodecane, octanol, decanol and octadecenol Higher alcohols such as are preferred. Furthermore, higher fatty acid esters and silicone oils can also be used as solvents.

Moreover, it is also preferable to use vegetable oil in combination with the above-mentioned solvent.
Examples of vegetable oil usable in the oil-based ink of the present invention include soybean oil, cottonseed oil, rapeseed oil, sesame oil, semi-drying oils such as corn oil, olive oil, peanut oil, non-drying oils such as soy sauce, linseed oil, Drying oils, such as flower oil, are mentioned.

Furthermore, the oil-based ink of the present invention can also contain an organic solvent.
Examples of the organic solvent usable in the oil-based ink of the present invention include lower alcohols such as methanol, ethanol and isopropyl alcohol, alkylene glycols such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol, ethylene glycol monobutyl ether, propylene Polyalkylene glycol ethers such as glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether and dipropylene glycol monomethyl ether can be mentioned.

1-6. Actinic Light Curing Ink The inkjet ink of the present invention is preferably an active light curable ink. The actinic radiation curable ink can contain a photopolymerizable compound and a photopolymerization initiator.

1-6-1. Photopolymerizable Compound Examples of the photopolymerizable compound include radically polymerizable compounds and cationically polymerizable compounds.
The photopolymerizable compound crosslinks or polymerizes by being irradiated with the above-mentioned actinic ray, and has the function of curing the ink. The photopolymerizable compound may be any of a monomer, a polymerizable oligomer, a prepolymer or a mixture thereof. In the ink of the present invention, only one type of photopolymerizable compound may be contained, or two or more types may be contained.

The content of the photopolymerizable compound is, for example, preferably in the range of 1 to 97% by mass with respect to the total mass of the ink of the present invention in view of film properties such as curability and flexibility, and 30 to 95 More preferably, it is in the range of mass%.
The radically polymerizable compound is preferably an unsaturated carboxylic acid ester, and more preferably (meth) acrylate.
In the present invention, “(meth) acrylate” means acrylate or methacrylate, “(meth) acryloyl group” means acryloyl group or methacryloyl group, and “(meth) acryl” is acrylic Or it means methacryl.

  Examples of (meth) acrylates include isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isomystil (meth) acrylate, isostearyl (meth) Acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, Methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, phenoxyethyl (meth) Acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- ( A single component comprising (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl 2-hydroxyethyl-phthalic acid and t-butylcyclohexyl (meth) acrylate Functional acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene Glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, dimethylol-tricyclodecanedi (meth) acrylate, di (meth) acrylate having bisphenol A structure, hydroxypivalate neopentyl glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, polyethylene glycol di Difunctional (meth) acrylates including acrylate and tripropylene glycol diacrylate, and trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, (Meta-functional or (meth) functional (meth) acrylates including pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin propoxy tri (meth) acrylate and pentaerythritol ethoxy tetra (meth) acrylate Included are oligomers having (meth) acryloyl groups, including acrylates, polyester acrylate oligomers, and modified products thereof.

Examples of the modified product include ethylene oxide modified (EO modified) acrylate having an ethylene oxide group inserted, and propylene oxide modified (PO modified) acrylate having a propylene oxide inserted.
(Meth) acrylate compound having a molecular weight in the range of 280 to 1,500 and a ClogP value in the range of 4.0 to 7.0 (hereinafter simply referred to as “(meth) acrylate compound A”) (Also referred to as
The (meth) acrylate compound A more preferably has two or more (meth) acrylate groups.
The molecular weight of the (meth) acrylate compound A is in the range of 280 to 1500 as described above, and more preferably in the range of 300 to 800.
In order to stably discharge the ink from the ink jet recording head, the ink viscosity at 80 ° C. can be set to 3 to 20, preferably 7 to 14 mPa · s.
By including a (meth) acrylate compound having a molecular weight of 280 or more and a gelling agent in the ink composition, the viscosity of the ink after landing can be increased, and the penetration of the ink into the substrate can be suppressed. The effect of suppressing the decrease in On the other hand, by including a (meth) acrylate compound having a molecular weight of 1,500 or less, an excessive increase in sol viscosity of the ink can be suppressed, and improvement in the gloss uniformity of the coating film can be expected.

Here, the molecular weight of the (meth) acrylate compound A can be measured using the following commercially available software package 1 or 2.
Software Package 1: MedChem Software (Release 3.54, August 1991, Medicinal Chemistry Project, Pomona College, Claremont, CA),
Software Package 2: Chem Draw Ultra ver. 8.0. (April 2003, CambridgeSoft Corporation, USA)

  In the present invention, when the ink contains (meth) acrylate compound A as at least a part of a photopolymerizable compound, an ink using a (meth) acrylate compound having a ClogP value of less than 4.0 as a photopolymerizable compound The gloss value tends to be lower than that. Therefore, it is preferable to use an ink for forming an image on a substrate having a relatively low 60 ° gloss value before corona discharge treatment, because the difference in gloss between a printed portion and a non-printed portion can be reduced. The (meth) acrylate compound A is more hydrophobic than a (meth) acrylate compound having a ClogP value of less than 4.0, so that more gelling agents repel and move to the surface of the cured film of the ink to increase unevenness. It is considered that the gloss value of the printed portion is lowered by this. Furthermore, the ClogP value of (meth) acrylate compound A is more preferably in the range of 4.5 to 6.0.

Here, “log P value” is a coefficient indicating the affinity of the organic compound to water and 1-octanol.
The 1-octanol / water partition coefficient P is the ratio of equilibrium concentrations of compounds in respective solvents at the distribution equilibrium when a trace amount of the compound is dissolved as a solute in the solvent of the two liquid phases of 1-octanol and water, Indicate their logarithm logP to base 10. That is, the “log P value” is a logarithmic value of the 1-octanol / water partition coefficient, and is known as an important parameter representing the hydrophobicity of molecules.

The "ClogP value" is a calculated logP value. The ClogP value can be calculated by a fragment method, an atom approach method or the like. More specifically, to calculate the ClogP value, the fragment described in the literature (C. Hansch and A. Leo, "Substituent Constants for Correlation Analysis in Chemistry and Biology" (John Wiley & Sons, New York, 1969)). The method or the following commercially available software package 1 or 2 may be used.
Software Package 1: MedChem Software (Release 3.54, August 1991, Medicinal Chemistry Project, Pomona College, Claremont, CA),
Software Package 2: Chem Draw Ultra ver. 8.0. (April 2003, CambridgeSoft Corporation, USA)
The numerical values of ClogP values described in the present specification and the like are “ClogP values” calculated using the software package 2.

  The amount of (meth) acrylate compound A contained in the ink is not particularly limited, but is preferably in the range of 1 to 40% by mass, and more preferably 5 to 30% by mass, based on the total mass of the ink. More preferable. When the amount of the (meth) acrylate compound A is 1% by mass or more, the ink does not become too hydrophilic and the gelling agent is sufficiently dissolved in the ink, so that the ink is likely to undergo a sol-gel phase transition. On the other hand, by setting the amount of (meth) acrylate compound A to 40% by mass or less, the photopolymerization initiator can be sufficiently dissolved in the ink.

More preferable examples of the (meth) acrylate compound A include (1) trifunctional or higher functional groups having 3 to 14 structures represented by (-C (CH ₃ ) H-CH ₂ -O-) in the molecule Included are methacrylate or acrylate compounds, and (2) bifunctional or higher methacrylate or acrylate compounds having a cyclic structure in the molecule. These (meth) acrylate compounds have high photocurability and little shrinkage when cured. Furthermore, the repeatability of the sol-gel phase transition is high.

The trifunctional or higher functional methacrylate or acrylate compound having 3 to 14 structures represented by (—C (CH ₃ ) H—CH ₂ —O—) in the molecule is, for example, 3 or more hydroxy groups. The hydroxy group of the compound possessed is propylene oxide modified, and the modified product obtained is esterified with (meth) acrylic acid.
Specific examples of this compound are
3PO modified trimethylolpropane triacrylate Photomer 4072 (molecular weight: 471, ClogP: 4.90, manufactured by Cognis),
3PO modified trimethylolpropane triacrylate Miramer M360 (molecular weight: 471, ClogP: 4.90, manufactured by Miwon)
Etc. are included.

The bifunctional or higher functional methacrylate or acrylate compound having a cyclic structure in the molecule is, for example, one obtained by esterifying the hydroxy group of a compound having two or more hydroxy groups and a tricycloalkane with (meth) acrylic acid .
Specific examples of this compound are
Tricyclodecane dimethanol diacrylate NK ester A-DCP (molecular weight: 304, ClogP: 4.69),
Tricyclodecane dimethanol dimethacrylate NK ester DCP (molecular weight: 332, ClogP: 5.12)
Etc. are included.
Another specific example of the (meth) acrylate compound A also includes 1,10-decanediol dimethacrylate NK ester DOD-N (molecular weight: 310, ClogP: 5.75, Shin-Nakamura Chemical Co., Ltd.) and the like.

The photopolymerizable compound may further contain a photopolymerizable compound other than the (meth) acrylate compound A.
Other photopolymerizable compounds include, for example, (meth) acrylate monomers or oligomers having a ClogP value of less than 4.0, (meth) acrylate monomers or oligomers having a ClogP value of more than 7.0, or other polymerizable compounds There are oligomers and the like.
Examples of these (meth) acrylate monomers or oligomers include 4EO modified hexanediol diacrylate (CD 561, manufactured by Sartomer, molecular weight 358); 3EO modified trimethylolpropane triacrylate (SR 454, manufactured by Sartomer, molecular weight 429); 4EO modified pentaerythritol tetraacrylate (SR494, manufactured by Sartomer, molecular weight 528); 6EO modified trimethylolpropane triacrylate (SR499, manufactured by Sartomer, molecular weight 560); caprolactone acrylate (SR495B, manufactured by Sartomer, molecular weight 344); polyethylene glycol Diacrylate (NK ester A-400, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 508), (NK ester A-600, Shin-Nakamura Chemical Co., Ltd.) , Molecular weight 708); polyethylene glycol dimethacrylate (NK ester 9G, manufactured by Shin-Nakamura Chemical Co., Ltd., molecular weight 536), (NK ester 14 G, manufactured by Shin-Nakamura Chemical Co., Ltd.); tetraethylene glycol diacrylate (V # 335 HP, Osaka Organic Chemical Company) Stearyl acrylate (STA, manufactured by Osaka Organic Chemical Co., Ltd.); phenol EO-modified acrylate (M144, manufactured by Miwon); nonylphenol EO-modified acrylate (M166, manufactured by Miwon) and the like.
Examples of other polymerizable oligomers include epoxy acrylates, aliphatic urethane acrylates, aromatic urethane acrylates, polyester acrylates, linear acrylic oligomers, and the like.

The cationically polymerizable compound used as the photopolymerizable compound may be an epoxy compound, a vinyl ether compound, an oxetane compound or the like.
As the cationically polymerizable compound, only one type may be contained in the actinic radiation curable inkjet ink, or two or more types may be contained.
The epoxy compounds are aromatic epoxides, alicyclic epoxides or aliphatic epoxides, and aromatic epoxides and alicyclic epoxides are preferred in order to enhance the curability.

The aromatic epoxide may be a di- or polyglycidyl ether obtained by reacting a polyhydric phenol or its alkylene oxide adduct with epichlorohydrin.
Examples of polyhydric phenols or alkylene oxide adducts thereof to be reacted include bisphenol A or alkylene oxide adducts thereof.
The alkylene oxide in the alkylene oxide adduct may be ethylene oxide, propylene oxide and the like.
The alicyclic epoxide may be a cycloalkane oxide-containing compound obtained by epoxidizing a cycloalkane-containing compound with an oxidizing agent such as hydrogen peroxide or peracid. The cycloalkane in the cycloalkane oxide-containing compound may be cyclohexene or cyclopentene.
The aliphatic epoxide may be a di- or polyglycidyl ether obtained by reacting an aliphatic polyhydric alcohol or its alkylene oxide adduct with epichlorohydrin.
Examples of aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, alkylene glycols such as 1,6-hexanediol, and the like. The alkylene oxide in the alkylene oxide adduct may be ethylene oxide, propylene oxide and the like.

Examples of vinyl ether compounds include ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether Monovinyl ether compounds such as -o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether and the like;
Diethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexane dimethanol divinyl ether, trimethylolpropane trivinyl ether, etc. Or trivinyl ether compounds and the like. Among these vinyl ether compounds, di- or trivinyl ether compounds are preferred in consideration of the curability and adhesion.

  The oxetane compound is a compound having an oxetane ring, and examples thereof include the oxetane compounds described in JP-A-2001-220526, JP-A-2001-310937, and JP-A-2005-255821. Among them, the compound represented by the general formula (1) described in paragraph 0089 of JP 2005-255821 A, the compound represented by the general formula (2) described in paragraph 0092 of the same publication, a paragraph number Examples thereof include a compound represented by General Formula (7), a compound represented by General Formula (8) of Paragraph No. 0109, a compound represented by General Formula (9) of Paragraph No. 0116, and the like. General formulas (1), (2), (7), (8) and (9) described in JP 2005-255821 A will be shown below.

1-6-2. Photopolymerization initiator When the photopolymerizable compound is a compound having a radically polymerizable functional group, the photopolymerization initiator includes a photoradical initiator, and the photopolymerizable compound has a cationically polymerizable functional group. When it is a compound which it has, a photo-acid generator is included.
In the ink of the present invention, only one type of photopolymerization initiator may be contained, or two or more types may be contained. The photopolymerization initiator may be a combination of both a photo radical initiator and a photo acid generator.
The photo radical initiator includes a cleavage type radical initiator and a hydrogen abstraction type radical initiator.

Examples of cleavable radical initiators include acetophenone based initiators, benzoin based initiators, acyl phosphine oxide based initiators, benzyl and methylphenylglyoxy esters.
Examples of acetophenone-based initiators include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2- Methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) Propan-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone are included.
Examples of benzoin-based initiators include benzoin, benzoin methyl ether and benzoin isopropyl ether.
Examples of acyl phosphine oxide based initiators include 2,4,6-trimethylbenzoin diphenyl phosphine oxide.

Examples of hydrogen abstraction type radical initiators include benzophenone-based initiators, thioxanthone-based initiators, aminobenzophenone-based initiators, 10-butyl-2-chloroacridone, 2-ethyl anthraquinone, 9,10- Included are phenanthrene quinone and camphor quinone.
Examples of benzophenone-based initiators include benzophenone, methyl 4-phenylbenzophenone o-benzoylbenzoate, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone And 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone and 3,3'-dimethyl-4-methoxybenzophenone.
Examples of thioxanthone-based initiators include 2-isopropyl thioxanthone, 2,4-dimethyl thioxanthone, 2,4-diethyl thioxanthone and 2,4-dichloro thioxanthone.
Examples of aminobenzophenone based initiators include Michler's ketone and 4,4'-diethylaminobenzophenone.

Examples of photoacid generators include the compounds described in "Organic Materials for Imaging", edited by Research Group of Organic Electronics Materials, Bunshin Publishing (1993), pp. 187-192.
The content of the photopolymerization initiator may be in the range in which the ink can be sufficiently cured, and can be, for example, in the range of 0.01 to 10% by mass with respect to the total mass of the ink of the present invention.

1-7. Other Components The ink of the present invention may further contain other components including a polymerization inhibitor and a surfactant as long as the effects of the present invention can be obtained. One of these components may be contained in the ink of the present invention, or two or more thereof may be contained.

1-7-1. Polymerization Inhibitor Examples of the polymerization inhibitor include (alkyl) phenol, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butyl catechol, t-butyl hydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-t-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cuperone, aluminum N-nitrosophenylhydroxyamine, tri-p-nitrophenylmethyl, N- (3 -Oxyanilino-1,3-dimethylbutylidene) aniline oxide, dibutylcresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime and cyclohexanone It contains oxime.

The amount of the polymerization inhibitor can be arbitrarily set as long as the effects of the present invention can be obtained.
The amount of the polymerization inhibitor can be, for example, 0.001% by mass or more and less than 1.0% by mass with respect to the total mass of the ink.

1-7-2. Surfactants Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols And nonionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers; cationic surfactants such as alkylamine salts and quaternary ammonium salts; and surfactants of silicone type and fluorine type. .

  Examples of silicone-based surfactants include polyether-modified polysiloxane compounds, specifically, KF-351A, KF-352A, KF-642 and X-22- 4272, manufactured by Shin-Etsu Chemical Co., Ltd., BYK 307, BYK 345 , BYK 347 and BYK 348, manufactured by Big Chemie ("BYK" is a registered trademark of the company), and TSF 4452 manufactured by Momentive Performance Materials.

The fluorine-based surfactant means a part or all of which is substituted with fluorine, instead of hydrogen bonded to carbon of the hydrophobic group of a normal surfactant.
Examples of fluorine-based surfactants include Megafac F, manufactured by DIC ("Megafac" is a registered trademark of the company), Surflon, manufactured by AGC Sei Chemical ("Surflon" is a registered trademark of the company), Fluorad FC, 3M Made in Japan (“Fluorad” is a registered trademark of the company), Monflor, Imperial Chemical Industries, Inc., Zonyls, E. I. Dupont Nemeras & Co., Licowet VPF, Rubebelke / Hoechst, and FTERGENT And Neos (FTERGENT is a registered trademark of the company).

  The amount of surfactant can be set arbitrarily as long as the effects of the present invention can be obtained. The amount of surfactant can be, for example, 0.001% by mass or more and less than 1.0% by mass with respect to the total mass of the ink.

1-8. Physical Properties From the viewpoint of enhancing the dischargeability from the inkjet head, the viscosity at 80 ° C. of the ink of the present invention is preferably in the range of 3 to 20 mPa · s, and is in the range of 7 to 9 mPa · s. Is more preferred. Further, from the viewpoint of causing the ink to be sufficiently gelled when the ink lands and is cooled to normal temperature, the viscosity at 25 ° C. of the ink of the present invention is preferably 1000 mPa · s or more.

It is preferable that the gelation temperature of the ink of this invention exists in the range of 30-70 degreeC. When the gelation temperature of the ink is 40 ° C. or more, the ink gels rapidly after landing on the recording medium, and thus the pinning property becomes higher. When the gelation temperature of the ink is 70 ° C. or less, the ink is less likely to gel when the violet ink is ejected from the inkjet head having an ink temperature of usually about 80 ° C., so the ink can be ejected more stably.
The gelation temperature of the ink of the present invention is more preferably in the range of 40 to 60 ° C. from the viewpoint of enabling discharge of the ink at a lower temperature and reducing the load on the image forming apparatus.

The viscosity at 80 ° C., the viscosity at 25 ° C., and the gelling temperature of the ink of the present invention can be determined by measuring the temperature change of the dynamic viscoelasticity of the ink with a rheometer.
In the present invention, these viscosity and gelation temperature are values obtained by the following method.
The ink of the present invention is heated to 100 ° C., and the shear rate is 11.7 while the viscosity is measured by a stress-controlled rheometer Physica MCR 301 (diameter of cone plate: 75 mm, cone angle: 1.0 °) manufactured by Anton Paar. The ink is cooled to 20 ° C. under the conditions of (1 / s), temperature decrease rate of 0.1 ° C./s to obtain a temperature change curve of viscosity.
The viscosity at 80 ° C. and the viscosity at 25 ° C. can be determined by reading the viscosity at 80 ° C. and 25 ° C., respectively, in the temperature change curve of viscosity. The gelation temperature can be determined as a temperature at which the viscosity is 200 mPa · s in the temperature change curve of viscosity.

From the viewpoint of enhancing the dischargeability from the ink jet head, the average dispersed particle diameter of the pigment particles according to the present invention is preferably in the range of 50 to 150 nm, and the maximum particle diameter is preferably in the range of 300 to 1000 nm. . A further preferable average dispersed particle size is in the range of 80 to 130 nm.
The average dispersed particle size of the pigment particles in the present invention means a value determined by a dynamic light scattering method using Datasizer Nano ZSP, manufactured by Malvern. In addition, since the ink containing the coloring material has a high density and light is not transmitted by this measuring device, the ink is diluted by 200 times and then measured. The measurement temperature is normal temperature (25 ° C.).

2. Image Forming Method The image forming method of the present invention comprises 1) the step of discharging the ink jet ink of the present invention from the nozzle of the ink jet head to land the ink on a recording medium, and 2) in the case of actinic radiation curable ink. Irradiating the landed ink with an actinic ray to cure the ink.

2-1. Step 1) In the step 1), ink droplets are ejected from an ink jet head to land on the position of the recording medium according to the image to be formed.
The discharge method from the inkjet head may be either an on-demand method or a continuous method.
On-demand ink jet heads include single-cavity, double-cavity, bender, piston, shear mode and shared wall electro-mechanical conversion systems, as well as thermal ink jet and bubble jet (registered trademark) (Bubble jet may be any of electro-thermal conversion system such as Canon-registered trademark type).

  Ejection stability can be enhanced by ejecting ink droplets from the ink jet head in a heated state. The temperature of the ink at the time of ejection is preferably in the range of 40 to 100 ° C., and in order to further enhance the ejection stability, it is more preferably in the range of 40 to 90 ° C. In particular, ejection is preferably performed at an ink temperature such that the viscosity of the ink is in the range of 7 to 15 mPa · s, more preferably in the range of 8 to 13 mPa · s.

  In the sol-gel phase transition type ink, the temperature of the ink when filled in the ink jet head is (gelling temperature + 10) ° C ~ (gelling) of the ink in order to enhance the dischargeability of the ink from the ink jet head. Preferably, the temperature is set to +30) ° C. When the temperature of the ink in the ink jet head is less than (gelling temperature +10) ° C., the ink is gelled in the ink jet head or on the nozzle surface, and the ink dischargeability tends to be reduced. On the other hand, if the temperature of the ink in the ink jet head exceeds (gelling temperature + 30) ° C, the ink becomes too hot, and the ink component may be degraded.

The method of heating the ink is not particularly limited. For example, at least one of an ink tank constituting a head carriage, an ink supply system such as a supply pipe and an ink chamber in the front chamber immediately before the head, a pipe with a filter, a piezo head, etc. be able to.
The amount of ink droplets when ejected is preferably in the range of 2 to 20 pL in terms of recording speed and image quality.

  The recording medium is not particularly limited, and is made of, for example, plastics such as polyester, polyvinyl chloride, polyethylene, polyurethane, polypropylene, acrylic resin, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate and polybutadiene terephthalate. Non-absorbing recording media (plastic base materials), non-absorbing inorganic recording media such as metals and glasses, and absorbing papers (for example, office copy paper, high quality paper for printing and coated paper for printing) can do.

2-2. Step 2) In the step 2), the ink landed on the recording medium in the step 1) is irradiated with an actinic ray to form an image formed by curing the ink.
The actinic ray may be selected from, for example, electron beam, ultraviolet ray, α ray, γ ray, and X ray, and preferably ultraviolet ray.
The irradiation of ultraviolet light can be performed under the conditions of a wavelength of 395 nm using, for example, a water-cooled LED manufactured by Phoseon Technology. By using the LED as a light source, curing failure of the ink due to melting of the ink by radiant heat of the light source can be suppressed.

The ultraviolet irradiation preferably has a peak illuminance on the image surface of ultraviolet light having a wavelength in the range of 370 to 410 nm, preferably in the range of 0.5 to ¹⁰ W / cm ² , more preferably in the range of 1 to 5 W / cm ² Do as you become. It is preferable that the light quantity irradiated to an image is less than 350 mJ / cm < ² > from a viewpoint of suppressing that radiation heat is irradiated to ink.
The irradiation of the actinic ray is preferably performed between 0.001 and 1.0 seconds after ink deposition, and may be performed between 0.001 and 0.5 seconds to form a high-definition image. More preferable.

The irradiation of actinic radiation may be performed in two steps.
First, an actinic ray may be irradiated during 0.001 to 2.0 seconds after the ink lands to temporarily cure the ink, and after all printing is completed, an actinic ray may be further irradiated to substantially cure the ink. . By dividing the irradiation of the actinic radiation into two steps, shrinkage of the recording material, which occurs upon curing of the ink, is less likely to occur.

EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
1. Ink Material 1-1. Compound of General Formula (I) <Synthesis Method of Compound of General Formula (I)>
<Composition of A-1>
In a 1000 mL four-necked flask, 450 parts by mass of chlorosulfonic acid were charged, and 45 parts by mass of 1-amino-4-hydroxy-2-phenoxy-9,10-anthraquinone was added little by little. Stirring was performed at 80 ° C. for 3 hours, and the disappearance of the raw material was confirmed by liquid chromatography. The reaction solution was added to 5000 parts by mass of ice water with stirring to precipitate a sulfonated product.
Then, the resultant was separated by filtration, washed with 2000 parts by mass of 0.1% hydrochloric acid, and further washed with 2000 parts by mass of purified water. Furthermore, by drying at 80 ° C., the following A-1 (sulfonic acid of general formula (II)) in which m ≒ 1 in general formula (I) was obtained.

<Composition of A-2>
In a 1000 mL four-necked flask, 90 parts by mass of aluminum chloride and 100 parts by mass of carbon disulfide were charged under an argon gas atmosphere, and 80 parts of oxalyl chloride dissolved in 200 parts by mass of carbon disulfide was added. Thereafter, 20 parts of 1-amino-4-hydroxy-2-phenoxy-9,10-anthraquinone suspended in 250 parts by mass of carbon disulfide was added dropwise over 1 hour. Stirring was carried out at 30 ° C. for 2 hours, and disappearance of the raw material was confirmed by liquid chromatography. The reaction solution was added to 5000 parts by mass of ice water with stirring to precipitate a carboxylate.
Then, the resultant was separated by filtration, washed with 2000 parts by mass of 0.1% hydrochloric acid, and further washed with 2000 parts by mass of purified water. By further drying at 80 ° C., the following A-2 (carboxylic acid of general formula (II)) in which mm1 in general formula (I) was obtained.

<Composition of B-1>
In a 1000 mL four-necked flask, 450 parts by mass of chlorosulfonic acid were charged, and 45 parts by mass of 1-hydroxy-4-[(4-methylpropyl) amino)]-9,10-anthraquinone was added little by little. Stirring was performed at 80 ° C. for 3 hours, and the disappearance of the raw material was confirmed by liquid chromatography. The reaction solution was added to 5000 parts by mass of ice water with stirring to precipitate a sulfonated product.
Then, the resultant was separated by filtration, washed with 2000 parts by mass of 0.1% hydrochloric acid, and further washed with 2000 parts by mass of purified water. Furthermore, by drying at 80 ° C., the following B-1 (sulfonic acid of general formula (III)) in which mm1 in general formula (I) was obtained.

<Composition of B-2>
In a 1000 mL four-necked flask, 90 parts of aluminum chloride and 100 parts of carbon disulfide were charged under an argon gas atmosphere, and 80 parts of oxalyl chloride dissolved in 200 parts of carbon disulfide was added. Thereafter, 20 parts of 1-hydroxy-4-[(4-methylpropyl) amino] -9,10-anthraquinone suspended in 250 parts of carbon disulfide was added dropwise over 1 hour. Stirring was carried out at 30 ° C. for 2 hours, and disappearance of the raw material was confirmed by liquid chromatography. The reaction solution was added to 5000 parts of ice water with stirring to precipitate a carboxylate.
Then, it was separated by filtration, washed with 2000 parts of 0.1% hydrochloric acid, and further washed with 2000 parts of purified water. By further drying at 80 ° C., the following B-2 (carboxylic acid of general formula (III)) in which m ≒ 1 in general formula (I) was obtained.

<Composition of C-1>
In a 1000 mL four-necked flask, 450 parts by mass of chlorosulfonic acid are charged, and 45 parts by mass of 1-amino-4- (ethylamino) -9,10-dioxo-9,10-dihydroanthracene-2-carbonitrile are added little by little. did. Stirring was performed at 80 ° C. for 3 hours, and the disappearance of the raw material was confirmed by liquid chromatography. The reaction solution was added to 5000 parts by mass of ice water with stirring to precipitate a sulfonated product.
Then, the resultant was separated by filtration, washed with 2000 parts by mass of 0.1% hydrochloric acid, and further washed with 2000 parts by mass of purified water. Further, by drying at 80 ° C., the following C-1 (1-amino-4- (ethylamino) -9,10-dioxo-9,10-dihydroanthracene-, in which m ≒ 1 in the general formula (I), is obtained A sulfonic acid of 2-carbonitrile (sulfonic acid of general formula (IV)) was obtained.

<Composition of C-2>
In a 1000 mL four-necked flask, 90 parts by mass of aluminum chloride and 100 parts by mass of carbon disulfide were charged under an argon gas atmosphere, and 80 parts of oxalyl chloride dissolved in 200 parts by mass of carbon disulfide was added. Thereafter, 20 parts of 1-amino-4- (ethylamino) -9,10-dioxo-9,10-dihydroanthracene-2-carbonitrile suspended in 250 parts by mass of carbon disulfide was added dropwise over 1 hour . Stirring was carried out at 30 ° C. for 2 hours, and disappearance of the raw material was confirmed by liquid chromatography. The reaction solution was added to 5000 parts by mass of ice water with stirring to precipitate a carboxylate.
Then, the resultant was separated by filtration, washed with 2000 parts by mass of 0.1% hydrochloric acid, and further washed with 2000 parts by mass of purified water. Further, by drying at 80 ° C., the following C-2 (1-amino-4- (ethylamino) -9,10-dioxo-9,10-dihydroanthracene-, in which m ≒ 1 in the general formula (I), is obtained The carboxylic acid of 2-carbonitrile (carboxylic acid of general formula (IV)) was obtained.

The compounds synthesized above are as follows.

1-2. Violet pigment PV23: C.I. I. Pigment Violet 23 (manufactured by Clariant, PV Fast Violet RL) was used.

PV 37: C.I. I. Pigment Violet 37 (manufactured by BASF, Cromophtal Violet D5808) was used.

1-3. Polymeric Dispersants Containing Basic Groups The polymeric dispersants shown in Table I were used. The amine value is a value measured according to JIS K 7237.

1-4. Gelling Agents The gelling agents shown in Table II were used.

1-5. Oily solvent, Isopar L (Exxon company, isoparaffin hydrocarbon solvent)
Octadecenol soy oil

1-6. Photopolymerizable compound APG-200 (manufactured by Shin-Nakamura Chemical Co., Ltd., tripropylene glycol diacrylate)
Miramer M360
(Miwon 3PO modified trimethylolpropane triacrylate)
・ NK ester A-400
(Shin-Nakamura Chemical Co., Ltd., polyethylene glycol # 400 diacrylate)
・ SR499
(Manufactured by SARTOMER, 6EO modified trimethylolpropane triacrylate)

1-7. Photopolymerization initiator · IRGACURE 819 (manufactured by BASF, acyl phosphine oxide)

1-8. Other components 1-8-1. Polymerization inhibitor, Irgastab UV-10 (manufactured by BASF)

1-8-2. Surfactant, KF-352 (Shin-Etsu Chemical Co., Ltd.)

2. Preparation of Ink 2-1. Preparation of Oil-Based Ink <Preparation of Oil-Based Ink O-1>
(Preparation of pigment dispersion)
The following components and 120 g of zirconia beads having a diameter of 0.5 mm were placed in a 200 mL poly bottle, the lid was closed, and dispersed for 4 hours with a vibrating mill (Red Devil 4500 L, manufactured by Nishimura Seisakusho). After dispersion, the beads were separated and the dispersion was taken out to obtain pigment dispersion 1.
Pigment: Said PV23: 20.0 mass%
Polymeric dispersant: D-1 described in Table I: 12.0% by mass
The compound of the general formula (I) according to the present invention: A-1: 1.4% by mass
Oily solvent: Isopar L (manufactured by Exxon): 69.0% by mass

(Preparation of ink)
The following additives were sequentially mixed, heated to 80 ° C. and stirred, and the obtained liquid was filtered with a # 3000 metal mesh filter under heating and cooled to prepare an ink O-1.
Oily solvent: Isopar L (manufactured by Exxon): 65.0% by mass
Oily solvent: Octadecenol: 10.0% by mass
Oily solvent: soybean oil: 10.0% by mass
Pigment dispersion 1 (above): 10.0% by mass
Gelling agent: G-1 described in Table II: 5.0% by mass

Preparation of Oil-Based Inks O-2 to O-68
Oil-based inks O-2 to O-68 were prepared in the same manner as in the preparation of oil-based ink O-1, except that various additives and addition amounts were changed as described in Tables III to V.

2-2. Preparation of actinic radiation curable ink <Preparation of actinic radiation curable ink U-1>
(Preparation of pigment dispersion)
The following components and 120 g of zirconia beads having a diameter of 0.5 mm were placed in a 200 mL poly bottle, the lid was closed, and dispersed for 4 hours with a vibrating mill (Red Devil 4500 L, manufactured by Nishimura Seisakusho). After dispersion, the beads were separated and the dispersion was taken out to obtain pigment dispersion 2.
Pigment: Said PV23: 20.0 mass%
Polymeric dispersant: Solsperse 39000 (manufactured by Lubrizol):
10.0 mass%
The compound of the general formula (I) according to the present invention: B-1: 1.0% by mass
Photopolymerizable compound: APG-200 (manufactured by Shin-Nakamura Chemical Co., Ltd.): 69.0 mass%

(Preparation of ink)
The following additives were sequentially mixed, heated to 80 ° C. and stirred, and the obtained liquid was filtered with a # 3000 metal mesh filter under heating and cooled to prepare Ink U-1.
Photopolymerizable compound: APG-200 (manufactured by Shin-Nakamura Chemical Co., Ltd.): 32.8 mass%
Photopolymerizable compound: Miramer M360 (manufactured by Miwon): 25.0% by mass
Photopolymerizable compound: NK ester A-400 (manufactured by Shin-Nakamura Chemical Co., Ltd.): 15.0% by mass
Photopolymerizable compound: SR499 (manufactured by SARTOMER): 10.0% by mass
Photopolymerization initiator: IRGACURE 819 (manufactured by BASF): 3.0% by mass
Polymerization inhibitor: Irgastab UV-10 (manufactured by BASF): 0.1% by mass
Surfactant: KF-352 (manufactured by Shin-Etsu Chemical Co., Ltd.): 0.1% by mass
Pigment dispersion 2 (above): 10.0% by mass
Gelling agent: G-2 Unistar M-2222 SL (manufactured by NOF Corporation): 4.0% by mass

<Preparation of Actinic Light Curing Inks U-2 to U-68>
The actinic radiation curable inks U-2 to U-68 were prepared in the same manner as in the preparation of the actinic radiation curable ink U-1 except that various additives and addition amounts were changed as described in Tables VI to VIII. Prepared.

3. Evaluation method and evaluation result 3-1. Evaluation method Pigment average dispersion particle diameter of the obtained ink, gloss value when forming an image using the ink, dot diameter, gloss value fluctuation when forming an image using the ink after high temperature storage The width and the dot diameter fluctuation range were evaluated by the following methods.

(Pigment average dispersed particle size)
The average dispersed particle diameter of the pigment particles contained in the obtained ink was measured by a dynamic light scattering method using Datasizer Nano ZSP, manufactured by Malvern. When the average dispersion particle size was in the range of 50 to 150 nm, the average dispersion particle size was determined to be good. When the average dispersed particle size was in the range of 80 to 130 nm, the average dispersed particle size was determined to be even better.

(The printing method of oil-based ink)
The obtained ink was introduced into an inkjet head HA 1024 type (manufactured by Konica Minolta) of a line type inkjet recording apparatus (manufactured by Konica Minolta). The temperature of the inkjet head was set to 80.degree. The ink is ejected under the conditions of resolution 720 × 720 dpi, ink droplet 8 pL, voltage 16 V to be deposited on a recording medium, and a solid image with a print width of 30 mm (30 mm × 100 mm) for gloss value measurement and for dot diameter measurement A dot image was formed. An OK top coat (manufactured by Oji Paper Co., Ltd.) was used as a recording medium.

(Printing method of actinic radiation curable ink)
The obtained ink was introduced into an inkjet head HA 1024 type (manufactured by Konica Minolta) of a line type inkjet recording apparatus (manufactured by Konica Minolta). The temperature of the inkjet head was set to 80.degree. Resolution 720 × 720 dpi, ink droplet 8 pL. After the ink is discharged under the condition of a voltage of 16 V to land on the recording medium, the landed ink droplet is irradiated with ultraviolet light of energy of 250 mJ / cm ² with an LED lamp to cure the ink droplet, A solid image with a print width of 30 mm (30 mm × 100 mm) for gloss value measurement and a dot image for dot diameter measurement were formed. An OK top coat (manufactured by Oji Paper Co., Ltd.) was used as a recording medium.

(Glossy value)
The solid image was measured for gloss value at 60 ° incident angle using a gloss meter. When the gloss value was in the range of 10 to 30, the gloss value was judged to be good. If the gloss value was in the range of 15 to 25, the gloss value was judged to be further good.

(Glossy value fluctuation after high temperature storage)
The obtained ink was collected in a heat-resistant tube and stored under high temperature conditions of 80 ° C. for 2 weeks. After high temperature storage, a solid image was formed by inkjet in the same manner as above, and the gloss value was measured. The difference between the image gloss values before storage and after high temperature storage (ie, the gloss value fluctuation range) was determined. When the gloss value fluctuation range was 10 or less, it was judged that the gloss value fluctuation after high temperature storage was good. If the gloss value fluctuation range was 5 or less, it was judged that the gloss value fluctuation after high temperature storage was even better.

(Dot diameter)
The dot image was observed under a condition of 100 times with a microscope to obtain an average size value of 10 droplets. The dot diameter was determined to be good if it was in the range of 50 to 70 μm. If the dot diameter is in the range of 55 to 65 μm, it is judged to be even better.

(Dot diameter fluctuation after high temperature storage)
The obtained ink was collected in a heat-resistant tube and stored under high temperature conditions of 80 ° C. for 2 weeks. After high temperature storage, dot images were formed by inkjet in the same manner as described above, and the dot diameter was measured. The difference between the dot diameters before and after storage (that is, the dot diameter fluctuation range) was determined. When the dot diameter fluctuation range was 10 μm or less, it was judged that the dot diameter fluctuation after high temperature storage was good. If the dot diameter fluctuation range was 5 μm or less, it was judged to be even better.

3-2. Evaluation result (Evaluation result of oil-based ink)
The evaluation results of Inks O-1 to O-56 (invention) are shown in Table III and Table IV, and the evaluation results of Inks O-57 to O-68 (Comparative Example) are shown in Table V.
As shown in Tables III and IV, all of the inks O-1 to O-56 (invention) containing the compound of the general formula (I) suppress the image gloss fluctuation and the dot diameter fluctuation after high temperature storage of the ink It is understood that
On the other hand, as shown in Table V, all of the inks O-57 to O-68 (comparative examples) not containing the compound of the general formula (I) can suppress the interaction between the pigment and the gelling agent. In addition, it can be understood that the image gloss fluctuation and the dot diameter fluctuation after the high temperature storage of the ink can not be sufficiently suppressed.
When a polymer dispersant having an amine value in the range of 30 to 80 mg KOH / g is used as the polymer dispersant, the average dispersed particle diameter of the pigment is small, and the image gloss fluctuation after the high temperature storage of the ink is further suppressed. It can be seen that the dot diameter fluctuation is more suppressed (ink No. O-1, O-12 vs. O-7, O-10, O-13, O-14, O-15).
In addition, it is understood that when the gelling agent selected from the general formula (G1) and the general formula (G2) is used as the gelling agent, the gloss value and the pinning property (dot diameter) show good values (ink No. 6). O-1, O-20 vs. O-21, O-22).

(Evaluation result of actinic radiation curable ink)
The evaluation results of Inks U-1 to U-56 (invention) are shown in Tables VI and VII, and the evaluation results of Inks U-57 to U-68 (Comparative Example) are shown in Table VIII.
As shown in Table VI and Table VII, all of the inks U-1 to U-56 (invention) containing the compound of the general formula (I) suppress image gloss fluctuation and dot diameter fluctuation after high temperature storage of the ink. It is understood that
On the other hand, as shown in Table VIII, each of the inks U-57 to U-68 (comparative example) not containing the compound of the general formula (I) suppresses the interaction between the pigment and the gelling agent. It can not be seen that the image gloss fluctuation and dot diameter fluctuation after high temperature storage of the ink can not be sufficiently suppressed.
When a polymer dispersant having an amine value in the range of 30 to 80 mg KOH / g is used as the polymer dispersant, the average dispersed particle diameter of the pigment is small, and the image gloss fluctuation after the high temperature storage of the ink is further suppressed. It can be seen that the dot diameter fluctuation is more suppressed (Ink Nos. U-1, U-12 and U-7, U-10, U-13, U-14, U-15 in comparison).
In addition, it is understood that when the gelling agent selected from the general formula (G1) and the general formula (G2) is used as the gelling agent, the gloss value and the pinning property (dot diameter) show good values (ink No. 6). U-1, U-20 versus U-21, U-22).

Claims (12)

An inkjet ink comprising a violet pigment having a dioxane structure, a polymer dispersant containing a basic group, and a gelling agent,
An inkjet ink comprising a compound having a structure represented by the following general formula (I).
General formula (I): [X]-(Y) _m
[Wherein, X has a structure represented by the following general formula (IA). Y is either a sulfonic acid group or a carboxy group, and Y can be present as a substitute for a hydrogen atom in a ring of the following general formula (IA), R ₁ , R ₂ or R ₃ . m represents an integer of 1 to 4; ]

[Wherein, R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, a halogen atom, an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkoxy group, a hydroxy group, an unsubstituted or substituted amino group Or represents an unsubstituted or substituted aryl group. ] The inkjet ink according to claim 1, wherein the general formula (IA) has a structure of any one of the structures represented by the following general formulas (II) to (IV).

[Wherein, R ₄ represents a hydrogen atom, an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group. In the general formula (I), Y may be present as a substituent in place of a hydrogen atom in the ring of the structure represented by the general formulas (II) to (IV) or R ₄ . ]   Content of the compound represented by the said General formula (I) is in the range of 2.0-10.0 mass% with respect to the said violet pigment, The claim 1 or 2 characterized by the above-mentioned. Inkjet ink as described.   The ink according to any one of claims 1 to 3, wherein the polymer dispersant has an amine value of 10 to 100 mg KOH / g.   The ink according to any one of claims 1 to 3, wherein the polymer dispersant has an amine value of 30 to 80 mg KOH / g.   The content of the said polymeric dispersing agent exists in the range of 30.0-70.0 mass% with respect to the said violet pigment in any one of Claim 1 to 5 characterized by the above-mentioned. Inkjet ink as described. The said gelatinizing agent contains at least 1 sort (s) chosen from the group which consists of a compound which has a structure represented by the following general formula (G1) and (G2), The any one of the Claims 1-6 characterized by the above-mentioned The inkjet ink according to any one of the preceding claims.
General Formula _{(G1): R 11 -CO-} R 12
Formula _{(G2): R 13 -COO-} R 14
[In formula, R < ₁₁ > -R < ₁₄ > respectively independently represents the alkyl group which may contain a linear part in the range of C12-C26, and may also contain branch. ]   The content of the gelling agent is in the range of 1.0 to 7.0% by mass with respect to the total mass of the ink according to any one of claims 1 to 7. Inkjet ink.   The violet pigment is at least C.I. I. Pigment Violet 23 or C.I. I. The inkjet ink according to any one of claims 1 to 8, comprising any of Pigment Violet 37.   The inkjet ink according to any one of claims 1 to 9, wherein the average dispersed particle size of the violet pigment is in the range of 50 to 150 nm.   The inkjet ink according to any one of claims 1 to 9, wherein an average dispersed particle size of the violet pigment is in a range of 80 to 130 nm.   The ink jet ink according to any one of claims 1 to 11, wherein the ink jet ink is an actinic ray curable ink jet ink containing a photopolymerizable compound and a photopolymerization initiator.