Pigment composition, and pigment dispersion and ink each containing same

Abstract

One embodiment of the present invention provides a pigment composition that contains: (A) C.I. Pigment Yellow 185; (B) a compound represented by general formula (i); and (C) a sulfonic acid metal salt which comprises a cationic moiety and an anionic moiety, wherein the cationic moiety contains a metal ion and the anionic moiety contains a structure represented by general formula (ii).

Description

Pigment compositions, pigment dispersions containing the same, and inks.

[0001] The present invention relates to a pigment composition, as well as a pigment dispersion and an ink containing the same.

[0002] Traditionally, pigments have been used primarily in inks, paints, toners, coloring of rubber and plastics, coloring of synthetic fiber stocks, pigment printing, and cosmetics. Among these, printing applications, such as inks, play a particularly important industrial role. For example, gravure inks and flexographic inks are widely used to impart aesthetic appeal and functionality to the printed substrates of flexible packaging films. Furthermore, with the recent proliferation of inkjet printers, expectations for the development of inkjet inks with superior performance are increasing.

[0003] Inkjet printers are widely used not only in homes but also in industrial applications, driven by the trend towards smaller print runs. In recent years, the business has expanded to include textile applications and flexible packaging. The pigments used in these inks require properties such as coloring power, lightfastness, and easy dispersibility.

[0004] For example, C.I. Pigment Yellow 185 (hereinafter also referred to as "PY185") has been conventionally used in ink applications as a greenish-yellow pigment with excellent properties such as lightfastness, heat resistance, and solvent resistance, and high coloring power (see, for example, Patent Document 1). The high fastness of PY185 is thought to be due to the fact that barbituric acid residues and amide bonds in the PY185 molecule form intermolecular hydrogen bonds, creating a strong crystalline structure. On the other hand, this also leads to the problem of increased interaction between particles and low dispersibility of the pigment in the dispersion medium. Low dispersibility results in a larger particle size of the pigment dispersed in the dispersion medium, and as a result, high viscosity. Furthermore, PY185 also has problems with dispersion stability, and the particle size of the dispersed particles tends to increase over time and the viscosity increases while stored dispersed in a dispersion medium.

[0005] Japanese Patent Publication No. 2014-55199

[0006] Under the above background, there is a need for a PY185 composition having more preferable properties. An object of the present invention is to provide a PY185 composition capable of obtaining a pigment dispersion excellent in properties such as small dispersed particle size, suppressed viscosity, and high dispersion stability.

[0007] As a result of intensive studies, the present inventors have found that by using PY185 in combination with a predetermined compound, a pigment dispersion excellent in properties such as small dispersed particle size, suppressed viscosity, and high dispersion stability can be obtained. The present invention is, for example, as follows. [1] (A) C.I. Pigment Yellow 185, and (B) a compound represented by the following general formula (i): [In general formula (i), R ｉ１ ~R ｉ１０ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent.], (C) a sulfonic acid metal salt containing a cationic part and an anionic part, wherein the cationic part contains a metal ion and the anionic part contains a structure represented by the following general formula (ii), and a sulfonic acid metal salt [In general formula (ii), R ｉｉ１ ~R ｉｉ５ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent.], a pigment composition. [2] The pigment composition according to [1], wherein R ｉ１ ~R ｉ１０ in the general formula (i) are each independently a hydrogen atom or a methyl group. [3] The pigment composition according to [1] or [2], wherein R ｉｉ１ ~R ｉｉ５ in the general formula (ii) are each independently a hydrogen atom or a methyl group. [4] The metal ion in the sulfonic acid metal salt (C) is aluminum ion (Al ３＋ ), sodium ion (Na ＋ ), potassium ion (K ＋ ), calcium ion (Ca ２＋ ), and barium ion (Ba ２＋A pigment composition according to any one of [1] to [3], selected from the group consisting of ) [5] The pigment composition according to any one of [1] to [4], wherein the compound (B) represented by the general formula (i) is contained in a proportion of 0.1 to 20% by mass per 100% by mass of the pigment composition [6] The pigment composition according to any one of [1] to [5], wherein the metal sulfonic acid salt (C) is contained in a proportion of 0.1 to 10% by mass per 100% by mass of the pigment composition [7] The pigment composition according to any one of [1] to [6], wherein the content ratio (mass ratio) of the compound (B) represented by the general formula (i) and the metal sulfonic acid salt (C) is (B):(C) = 1:10 to 10:1 [8] The pigment composition according to any one of [1] to [7], wherein the pH is 4.0 or higher [9] A pigment dispersion comprising the pigment composition according to any one of [1] to [8] and a dispersion medium

[10] The pigment dispersion according to [9], further comprising a dispersant.

[11] An ink comprising the pigment dispersion described in [9] or

[10] .

[12] The ink described in

[11] , which is an active energy ray curable inkjet ink.

[13] The ink described in

[11] or

[12] , wherein the viscosity (at 20°C) is 17.5 mPa·s or less.

[14] The ink described in any of

[11] to

[13] , wherein the volume-average dispersed particle diameter (Mv) is 200 nm or less.

[15] The sulfonic acid metal salt (C) is a product of step 1, which involves a coupling reaction between a bisdiazonium salt represented by the following formula (a), an acetoacetate anilide derivative represented by the following formula (b), and a potassium sulfonic acid salt represented by the following formula (c), The compound is produced by a method comprising step 1, step 2, which involves substituting potassium ions in the compound obtained in step 1 with desired metal ions (in formula (b), R ｉｉ１ ~R ｉｉ５ A pigment composition according to any one of [1] to [8], where each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have substituents.

[16] The metal ion is an aluminum ion (Al ３＋ ), sodium ions (Na ＋ ), potassium ions (K ＋ ), calcium ions (Ca ２＋ ) and barium ions (Ba２＋ A pigment composition selected from the group consisting of

[15] .

[17] R in the general formula (i) ｉ１ ~R ｉ１０ Each is independently a hydrogen atom or a methyl group; R in the general formula (ii) ｉｉ１ ~R ｉｉ５ Each is independently a hydrogen atom or a methyl group; the metal ion in the sulfonic acid metal salt (C) is an aluminum ion (Al ３＋ ), sodium ions (Na ＋ ), potassium ions (K ＋ ), calcium ions (Ca ２＋ ) and barium ions (Ba ２＋ A pigment composition selected from the group consisting of [1] to [8].

[0008] According to the present invention, it is possible to provide a PY185 composition that yields a pigment dispersion with excellent properties such as small dispersion particle size, suppressed viscosity, and high dispersion stability.

[0009] Embodiments of the present invention will be described in detail below. According to one embodiment, the pigment composition of the present invention comprises the following components (A) to (C): (A) C.I. Pigment Yellow 185, and (B) a compound represented by the following general formula (i), [In general formula (i), R ｉ１ ~R ｉ１０ Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may have substituents. (C) A metal sulfonic acid salt comprising a cation part and an anion part, wherein the cation part contains a metal ion and the anion part comprises a structure represented by the following general formula (ii). [In general formula (ii), R ｉｉ１ ~R ｉｉ５ Each of these independently represents an alkyl group having 1 to 6 carbon atoms, which may have a hydrogen atom or a substituent.

[0010] As a result of diligent research, the inventors have found that by using compound (B) and metal sulfonic acid salt (C) (hereinafter also referred to as "compound (C)") represented by the above general formula (i) in combination with PY185, a pigment dispersion with low viscosity can be obtained. This is thought to be due to the fact that when a pigment composition containing the above components (A) to (C) is used as a pigment dispersion, the interaction between the pigment composition particles becomes smaller. As a result, the particle size of the dispersed pigment composition in the pigment dispersion becomes smaller, high dispersibility of the pigment composition is achieved, and the viscosity of the pigment dispersion becomes lower. Using such a pigment dispersion as an inkjet ink has the advantage of preventing clogging of the nozzle head of an inkjet printer. Furthermore, the pigment composition according to the embodiment also has excellent dispersion stability, so when stored as a pigment dispersion, the increase in the particle size of the dispersed pigment composition over time is suppressed, and as a result, the increase in viscosity of the pigment dispersion is also suppressed. Therefore, the pigment composition according to the embodiment maintains its quality even when stored for a long period of time as a pigment dispersion or ink, that is, it has excellent storage stability.

[0011] The reason for these effects is not entirely clear, but it is speculated that the following may be the case. To improve the dispersibility of organic pigment compounds, compounds with substituents such as sulfonic acid groups are sometimes used in combination. In this case, it is generally preferred to use a compound (hereinafter also referred to as a "pigment compound derivative") that has the same or similar skeletal structure as the organic pigment compound and into which substituents such as sulfonic acid groups have been introduced. This is because the closer the structures of the organic pigment compound and the pigment compound derivative are, the stronger the pigment compound derivative will adsorb to the surface of the organic pigment compound, and a high dispersibility improvement effect can be expected.

[0012] However, due to constraints such as reaction mechanisms, production equipment, and chemical registrations, it may be difficult to prepare an organic pigment compound for which improved dispersibility is desired and a pigment compound derivative having the same or a similar skeletal structure. Therefore, a compound having a skeletal structure different from that of the organic pigment compound (hereinafter also referred to as a "heterogeneous derivative") may be used. However, due to the difference in their structures, heterogeneous derivatives have weak adsorption to the particle surface of the organic pigment compound, and when used as a pigment dispersion, the heterogeneous derivatives elute into the solvent component, resulting in the problem that the intended dispersibility improvement effect cannot be sufficiently obtained.

[0013] Therefore, in the present invention, in order to solve the above problems, in addition to the organic pigment compound and the heterogeneous derivative, a compound that mediates the adsorption between the organic pigment compound and the heterogeneous derivative is further used. In the present invention, PY185 is the organic pigment compound, the compound represented by the general formula (i) (hereinafter also referred to as "compound (B)") is the compound that mediates the adsorption between the organic pigment compound and the heterogeneous derivative, and the sulfonic acid metal salt (hereinafter also referred to as "compound (C)") corresponds to the heterogeneous derivative, respectively.

[0014] Although PY185 and the compound (B) represented by the general formula (i) have different skeletal structures, the compound represented by the general formula (i) does not have a substituent that improves solubility in a solvent. Therefore, when these are used as components of a pigment dispersion, it is considered that the compound (B) represented by the general formula (i) remains on the surface of the PY185 particles without dissolving in the solvent. And since the compound (B) represented by the general formula (i) and the sulfonic acid metal salt (C) have similar structures, it is considered that the sulfonic acid metal salt strongly adsorbs to the compound (B) represented by the general formula (i) located on the surface of PY185. Then, the sulfonic acid metal salt (C) can exist on the surface of PY185 through the compound (B) represented by the general formula (i) in the pigment dispersion. As a result of introducing the sulfonic acid group in this way, it is presumed that the pigment composition according to the embodiment has excellent dispersibility in the pigment dispersion.

[0015] Hereinafter, the components, manufacturing methods, physical properties, uses, etc. of the pigment composition, pigment dispersion, and ink according to the embodiment will be described in detail. In the present application, PY185 does not merely mean only the compound having the structure shown below, but also means the pigment composed of the compound. The pigment is not only characterized by its crystal structure, but also includes substances characterized by physical properties such as primary particles aggregated and / or assembled therefrom, and further aggregates and / or assemblies resulting from its surface state, etc.

[0016] 〔Pigment Composition〕[A] C.I. Pigment Yellow 185 (PY185) PY185 is an isoindoline-based yellow pigment and is represented by, for example, the following structural formula. The pigment composition according to the embodiment may contain at least PY185 as a colorant, and may contain pigments and dyes other than PY185 as long as the effects of the present invention are not impaired.

[0017] PY185 can be produced, for example, by obtaining diiminoisoindoline from phthalonitrile and ammonia and then condensing it with N-methylcyanoacetamide and barbituric acid. As PY185, commercially available products may be used as they are. Commercially available products include C.I. Pigment Yellow 185 (manufactured by SunChemical), C.I. Pigment Yellow 185 (manufactured by SY Chemical), C.I. Pigment Yellow 185 (manufactured by ZeyaChemicals), C.I. Pigment Yellow 185 (manufactured by TrustChem), C.I. Pigment Yellow 185 (manufactured by Vijay Chemical Industries), C.I. Pigment Yellow 185 (manufactured by Anshan Hifichem), etc. The pigment composition according to the embodiment may contain one or more types of PY185.

[0018] The average aspect ratio (major diameter / minor diameter) of PY185 is preferably 1.00 to 10.00, more preferably 1.00 to 5.00, and particularly preferably 1.50 to 4.00, from the viewpoint of suppressing aggregation of pigments. The average particle diameter (minor diameter) of PY185 is preferably 1 to 75 nm, more preferably 5 to 50 nm, and particularly preferably 10 to 30 nm, from the viewpoint of increasing the print density (OD). Furthermore, the average particle diameter (major diameter) of PY185 is preferably a value such that the average value of the average aspect ratio and minor diameter falls within the above range, but is preferably 20 to 150 nm, more preferably 30 to 100 nm, and particularly preferably 40 to 60 nm. The average particle diameter (major diameter, minor diameter) can be measured by image analysis using an electron microscope as described in the examples below, and the average aspect ratio can be calculated by the formula "average particle diameter (major diameter) / average particle diameter (minor diameter)".

[0019] The specific surface area of ​​PY185 is preferably 20 to 90 m², from the viewpoint of fluidity and coloring power when used as an ink. ２ / g, more preferably 25 to 60m ２ / g, particularly preferably 30 to 50m ２ The specific surface area is / g. The specific surface area can be measured using a fully automatic specific surface area measuring device as described in the examples below. PY185 is preferably included in a proportion of 70.0 to 99.8% by mass, more preferably 77.5 to 99.3% by mass, and particularly preferably 85.0 to 98.5% by mass, based on 100% by mass of the pigment composition. By having a PY185 content within the above range, a pigment composition with excellent coloring power while achieving the desired effect can be obtained.

[0020] [B] The pigment composition according to the compound embodiment represented by general formula (i) contains one or more compounds represented by the following general formula (i). Since the compound represented by general formula (i) is an azo-hydrazo tautomer, it may contain both the azo compound (-N=N-) and the hydrazo compound (>N-NH-). [In general formula (i), R ｉ１ ~R ｉ１０Each of these independently represents an alkyl group having 1 to 6 carbon atoms, which may have a hydrogen atom or a substituent. The alkyl group having 1 to 6 carbon atoms may be linear or branched, and is preferably a propyl group, an ethyl group, or a methyl group. Of these, an ethyl group or a methyl group is more preferable, and a methyl group is particularly preferable because it is easy to obtain as a raw material and has low cost. Also, R ｉ１ ~R ｉ１０ Each of these is preferably independently a hydrogen atom or a methyl group. The alkyl group may have substituents, and such substituents include, but are not limited to, hydroxyl groups, formyl groups, carbonyl groups, carboxyl groups, nitro groups, amino groups, vinyl groups, aryl groups, and halogen groups.

[0021] As for compounds represented by general formula (i), the compounds represented by the following structural formulas (i-1) to (i-3) are preferred.

[0022] The compound represented by general formula (i) is preferably included in a proportion of 0.1 to 20.0% by mass, more preferably 0.5 to 15.0% by mass, and particularly preferably 1.0 to 10.0% by mass, based on 100% by mass of the pigment composition. By including the compound represented by general formula (i) in such an amount, the desired effects (dispersibility, dispersion stability, etc.) can be successfully obtained.

[0023] The compound represented by general formula (i) can be obtained, for example, by mixing 3,3'-dichlorobenzidine dihydrochloride with an aqueous sodium nitrite solution under ice-cold conditions, reacting the diazotization reaction to obtain a bisdiazonium salt solution, and then coupling the solution with an acetoacetate anilide derivative having the desired substituent. Alternatively, commercially available products can be used as the compound represented by general formula (i), and examples of commercially available products include C.I. Pigment Yellow 12 (manufactured by DIC Corporation), C.I. Pigment Yellow 13 (manufactured by DIC Corporation), and C.I. Pigment Yellow 14 (manufactured by DIC Corporation).

[0024] [C] The pigment composition according to the metal sulfonate salt embodiment comprises one or more metal sulfonates including a cationic portion and an anionic portion. The cationic portion contains a metal ion, and the anionic portion includes a structure represented by the following general formula (ii). [In general formula (ii), R ｉｉ１ ~R ｉｉ５ Each of these independently represents an alkyl group having 1 to 6 carbon atoms, which may have a hydrogen atom or a substituent. The alkyl group having 1 to 6 carbon atoms may be linear or branched, and is preferably a propyl group, an ethyl group, or a methyl group. Of these, an ethyl group or a methyl group is more preferable, and a methyl group is particularly preferable because it is easy to obtain as a raw material and has low cost. Also, R ｉｉ１ ~R ｉｉ５ Each of these is preferably a hydrogen atom or a methyl group, independently of the others. The alkyl group may have substituents, and such substituents include, but are not limited to, hydroxyl, formyl, carbonyl, carboxyl, nitro, amino, vinyl, aryl, and halogen groups. The structure of general formula (ii) is an azo-hydrazo tautomer and therefore may include both the azo (-N=N-) and hydrazo (>N-NH-) forms.

[0025] The metal ions contained in the cation are sodium ions (Na ＋ ), potassium ions (K ＋ ), calcium ions (Ca ２＋ ), barium ions (Ba ２＋ ), aluminum ions (Al ３＋ Examples include aluminum ions (Al ３＋ ) is preferable.

[0026] Specific examples of the anionic portion in the metal sulfonic acid salt (C) include structures represented by the following formulas (ii-1) to (ii-9).

[0027] The anionic portion of the metal sulfonic acid salt (C) preferably has a structure corresponding to or similar to the compound (B) represented by general formula (i) used together, and more preferably is a sulfonic acid derivative of compound (B) represented by general formula (i). This is because such a structure for the anionic portion of the metal sulfonic acid salt (C) strengthens the adsorption force between compound (B) represented by general formula (i) and the metal sulfonic acid salt (C), thereby achieving a greater effect in improving dispersibility and dispersion stability. In other words, R in general formula (i) ｉ１ ~R ｉ５ R in general formula (ii) ｉｉ１ ~R ｉｉ５ It is particularly preferable that they are identical.

[0028] Here, if the metal ion is a polyvalent ion, the bonding state between it and the anion is uncertain, so the structure of the sulfonic acid metal salt (C) cannot be clearly shown. It is speculative, but possible structures include, for example, a structure in which two or more structures represented by the above general formula (ii) are bonded around the polyvalent ion, or a structure in which a hydroxide ion is bonded to the polyvalent ion in addition to the structure represented by the above general formula (ii).

[0029] As mentioned above, it is currently impossible and impractical to show the specific structure of the sulfonic acid metal salt (C). However, the sulfonic acid metal salt (C) can be produced, for example, by the same method as the method for producing compound (B) represented by general formula (i) described above, either simultaneously with or separately from compound (B) represented by general formula (i). More specifically, a bisdiazonium salt is prepared in the same manner as the method for producing the compound represented by general formula (i), and then coupled with an acetoacetate anilide derivative having the desired substituent and its potassium sulfonic acid salt. Furthermore, by reacting it with a metal compound such as aluminum sulfate, the sulfonic acid metal salt (C) can be obtained by substituting the potassium ion in the compound obtained by the coupling reaction with the desired metal ion. In this case, it is presumed that not only is the potassium ion simply substituted with the desired metal ion, but multiple anionic moieties may associate with the metal ion, or hydroxide ions may be bound to it.

[0030] Therefore, according to one embodiment, the metal sulfonic acid salt (C) is produced by a coupling reaction of a bisdiazonium salt represented by the following formula (a) with an acetoacetate anilide derivative represented by the following formula (b) and a potassium sulfonic acid salt represented by the following formula (c), The compound is produced by a method comprising step 2, in which the potassium ions in the compound obtained in step 1 are replaced with desired metal ions. Here, the metal ions are as described above as metal ions contained in the cation portion of the sulfonic acid metal salt (C). Furthermore, substituent R of the compound represented by formula (b) above. ｉｉ１ ~R ｉｉ５ The definition is as defined above for general formula (ii).

[0031] The above coupling reaction is preferably carried out under acidic to neutral conditions (e.g., pH 2 to 8) and at low to room temperature (e.g., 0 to 40°C, preferably 0 to 5°C). The subsequent metal ion substitution step is carried out by adding a compound containing the desired metal ion, and is preferably carried out at a higher temperature (e.g., 40 to 80°C).

[0032] The metal sulfonate salt (C) is preferably included in an amount of 0.1 to 10.0% by mass, more preferably 0.2 to 7.5% by mass, and particularly preferably 0.5 to 5.0% by mass, based on 100% by mass of the pigment composition. By including the metal sulfonate salt (C) in such amounts, the desired effects (dispersibility, dispersion stability, etc.) can be successfully obtained.

[0033] The ratio (mass ratio) of compound (B) represented by general formula (i) to metal sulfonate salt (C) is preferably (B):(C) = 1:10 to 10:1, more preferably (B):(C) = 1:2 to 5:1, and particularly preferably (B):(C) = 1:1 to 3:1. A higher ratio (mass%) of compound (B) represented by general formula (i) than of metal sulfonate salt (C) is preferable in terms of effectiveness.

[0034] The pigment composition according to the embodiment may further contain a metal sulfonic acid salt whose anion portion has a structure represented by the following general formula (iii). Such a metal sulfonic acid salt may be present in the form of only one type or two or more types. The structure of general formula (iii) is an azo-hydrazo tautomer, and therefore may include both the azo isomer (-N=N-) and the hydrazo isomer (>N-NH-). In this case, the cation moiety is as described above for the sulfonic acid metal salt having an anion moiety represented by general formula (ii).

[0035] Furthermore, the situation in which the structure of the sulfonic acid metal salt cannot be clearly shown when the metal ion in the cation part is a polyvalent ion is the same as described above. However, examples of the structure of the anion part represented by general formula (iii) include the structures represented by the following formulas (iii-1) to (iii-3).

[0036] A metal sulfonic acid salt having an anion portion represented by general formula (iii) is preferably included in a proportion of 0.1 to 10.0% by mass, more preferably 0.2 to 7.5% by mass, and particularly preferably 0.5 to 5.0% by mass, based on 100% by mass of the pigment composition.

[0037] [3] Other Components The pigment composition according to the embodiment may contain yellow pigments or dyes in addition to PY185 as pigment components. Examples of yellow pigments include azo, disazo, azomethine, anthraquinone, quinophthalone, benzimidazolone, isoindoline, quinacridone, and perinone pigments, and more specifically, C.I. Examples of pigment yellows include 1, 2, 3, 12, 13, 14, 16, 17, 20, 23, 24, 34, 35, 37, 53, 55, 73, 74, 75, 81, 83, 86, 93, 95, 97, 98, 100, 101, 104, 108, 109, 110, 114, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 213, etc. Other dyes and pigments besides these yellow pigments may also be included.

[0038] The pigment composition according to the embodiment may further contain other components commonly used in pigment compositions. The proportion of the other components in the pigment composition is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass.

[0039] The pigment composition according to the embodiment can be produced by mixing the above-described components. The mixing can be carried out by methods commonly used in the art, such as blending using a mixer. The mixed state of the pigment composition is not particularly limited.

[0040] The pH of the pigment composition is preferably 4.0 or higher, more preferably 4.0 to 8.0, and particularly preferably 4.3 to 7.0, from the viewpoint of dispersibility and dispersion stability. The pH can be measured by the method described in JIS K 5101-17-1:2004.

[0041] [Pigment Dispersion] According to another embodiment of the present invention, a pigment dispersion is provided comprising the above-described pigment composition and a dispersion medium. In the pigment dispersion, the pigment composition exists in a dispersed state in the dispersion medium. As the dispersion medium, any material commonly used in the art that can disperse the pigment composition can be appropriately selected and used, but examples include water and water-soluble organic solvents, with water being preferred. Examples of water-soluble organic solvents include alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, 1,2-hexanediol, and 1,6-hexanediol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycols; and lactams such as N-methyl-2-pyrrolidone. These organic solvents may be used alone or in combination of two or more. Alternatively, a mixture of water and an organic solvent may be used.

[0042] In the pigment dispersion, the above-mentioned pigment composition and dispersion medium are preferably mixed in a ratio of 1:3 to 1:10, more preferably 1:6 to 1:8 (by mass). Mixing can be carried out by methods commonly used in the art, such as a mixing method using a dispenser. The mixing state of the pigment dispersion is not particularly limited. PY185 is preferably included in a ratio of 5 to 30% by mass, and more preferably in a ratio of 8 to 15% by mass, per 100% by mass of the pigment dispersion.

[0043] The pigment dispersion may further contain a dispersant. Such a dispersant can be any agent that disperses PY185, and examples include copolymers (e.g., block copolymers, random copolymers, and graft copolymers) composed of at least two monomers selected from the group consisting of monomers such as styrene and its derivatives, vinylnaphthalene and its derivatives, aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids, acrylic acid and its derivatives, maleic acid and its derivatives, itaconic acid and its derivatives, fumaric acid and its derivatives, vinyl acetate, vinyl alcohol, vinylpyrrolidone, and acrylamide.

[0044] As a dispersant, commercially available products may be used. Examples of such dispersants include the SOLSPERSE series from Lubrizol, the Disperbyk series and BYKJET series from BIC Chemie, the EFKA series from BASF, and the Azisper series from Ajinomoto Fine Techno.

[0045] Examples of the SOLSPERSE series include SOLSPERSE11200, SOLSPERSE13240, SOLSPERSE13650, SOLSPERSE13940, SOLSPERSE16000, SOLSPERSE17000, SOLSPERSE18000, SOLSPERSE20000, SOLSPERSE24000, SOLSPERSE24000SC, SOLSPERSE24000GR, SOLSPERSE2600, SOLSPERSE28000, SOLSPERSE31845, This includes SOLSPERSE32000, SOLSPERSE32500, SOLSPERSE32550, SOLSPERSE32600, SOLSPERSE33000, SOLSPERSE34750, SOLSPERSE35100, SOLSPERSE35200, SOLSPERSE37500, SOLSPERSE38500, SOLSPERSE39000, SOLSPERSE56000, SOLSPERSE71000, SOLSPERSE73000, SOLSPERSE74000, etc.

[0046] Examples of the Disperbyk series include Disperbyk-101, Disperbyk-108, Disperbyk-109, Disperbyk-112, Disperbyk-116, Disperbyk-130, Disperbyk-140, Disperbyk-142, Disperbyk-145, Disperbyk-161, Disperbyk-162, Disperbyk-163, Disperbyk-164, Disperbyk-166, Dispe This includes rbyk-167, Disperbyk-168, Disperbyk-180, Disperbyk-182, Disperbyk-183, Disperbyk-185, Disperbyk-184, Disperbyk-2000, Disperbyk-2001, Disperbyk-2008, Disperbyk-2020, Disperbyk-2050, Disperbyk-2070, Disperbyk-2150, Disperbyk-2155, etc.

[0047] Examples of the BYKJET series include BYKJET-9131, BYKJET-9132, BYKJET-9133, BYKJET-9142, BYKJET-9150, BYKJET-9151, BYKJET-9152, BYKJET-9170, BYKJET-9171, BYKJET-9175, BYKJET-9177, and others.

[0048] Examples of the EFKA series include EFKA4008, EFKA4046, EFKA4047, EFKA4015, EFKA4020, EFKA4050, EFKA4055, EFKA4060, EFKA4080, EFKA4300, EFKA4330, EFKA4400, EFKA4401, EFKA4402, EFKA4403, EFKA4500, EFKA4510, EFKA4530, EFKA4800, EFKA PX4701, EFKA PX4703, and others.

[0049] Examples of the Azisper series include Azisper PB-711, Azisper PB-821, Azisper PB-822, etc. The amount of dispersant added is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass, as solid content, based on 100% by mass of the pigment dispersion. The pigment dispersion may also contain additives other than the dispersant, such as preservatives, pH adjusters, water-soluble polymer compounds, water-dispersible resins, surfactants, etc. The amount of other additives added is preferably 0 to 30% by mass, more preferably 0 to 15% by mass, based on 100% by mass of the pigment dispersion.

[0050] [Ink] In further embodiments, an ink comprising a pigment dispersion is provided. The pigment dispersion may be used as an ink as is, or further components may be added to the pigment dispersion to form an ink. The type of ink is not particularly limited, but examples include gravure ink, flexographic ink, and inkjet ink. Among these, inkjet ink is preferred due to its cost-effectiveness and ability to print on a variety of materials, and active energy ray curable inkjet ink (e.g., UV curable inkjet ink) is particularly preferred.

[0051] According to one embodiment, the ink is produced by further adding and mixing a dispersion medium and additives commonly used in the field to the pigment dispersion described above. The dispersion medium for the ink is not particularly limited, but examples include those similar to the dispersion medium described for the pigment dispersion. The mixing method is also not particularly limited and can be mixed by methods commonly used in the field, but examples include mixing methods using a dispensing machine.

[0052] The ink may contain additives commonly used in the field, as needed. Such additives include, for example, preservatives, pH adjusters, chelating agents, rust inhibitors, water-soluble UV absorbers, water-soluble polymer compounds, antioxidants, water-dispersible resins, and surfactants. Surfactants include anionic, cationic, nonionic, amphoteric, silicone-based, and fluorine-based surfactants. In the case of water-based inks, water or water-soluble organic solvents may be added to adjust the ink concentration.

[0053] The ratio of the additive to the total mass of the ink according to the embodiment (the total amount if two or more additives are included) is preferably 0 to 30% by mass, more preferably 0 to 15% by mass. It is preferable that PY185 is included in an amount of 2 to 10% by mass, and more preferably 3 to 5% by mass, per 100% by mass of ink.

[0054] The pH of the ink according to this embodiment is, for example, 7.0 or higher, preferably 7.5 or higher, from the viewpoint of further improving the storage stability of the ink. Also, from the viewpoint of material resistance and skin irritation, the pH is, for example, 11.0 or lower, preferably 10.0 or lower.

[0055] The viscosity of the ink (initial) is preferably 17.5 mPa·s or less, more preferably 3.0 to 17.5 mPa·s, and particularly preferably 10.0 to 15.0 mPa·s, from the viewpoint of forming appropriate ink droplets and obtaining good images. Furthermore, the viscosity of the ink after storage at 50°C for one week is preferably 40.0 mPa·s or less, more preferably 10.0 to 40.0 mPa·s, and particularly preferably 15.0 to 25.0 mPa·s. The viscosity of the ink can be measured by the method described in the examples below. The difference (change) between the initial viscosity and the viscosity after storage is preferably 15.0 mPa·s or less, more preferably 10.0 Pa·s or less, and particularly preferably 5.0 mPa·s or less.

[0056] The initial volume-average dispersed particle diameter (Mv) of the ink is preferably 200 nm or less, more preferably 50 to 200 nm, and particularly preferably 75 to 120 nm, from the viewpoint of preventing nozzle clogging of the inkjet head. Furthermore, the volume-average dispersed particle diameter (Mv) of the ink after storage at 50°C for one week is preferably 500 nm or less, more preferably 130 to 500 nm, and particularly preferably 150 to 310 nm or 150 to 200 nm. The volume-average dispersed particle diameter (Mv) of the ink can be measured by the method described in the examples below. The difference (change) between the initial and stored volume-average dispersed particle diameters (Mv) is preferably 300 nm or less, more preferably 210 nm or less, and particularly preferably 100 nm or less.

[0057] When the ink according to the embodiment is used as an inkjet ink, it can be loaded into a known inkjet recording device and ejected as ink droplets onto a recording medium to record images, etc. Inkjet recording devices include continuous ejection type (charge-controlled type, spray type, etc.) and on-demand type (piezo type, thermal type, electrostatic attraction type, etc.), but the ink according to the embodiment can be used with any of these types.

[0058] According to one embodiment, the ink of the embodiment is an active energy ray curable inkjet ink. Active energy ray curable inkjet ink is cured by irradiation with light such as active energy rays, preferably ultraviolet light. As the light source, a light source that is normally used for active energy ray curable inkjet printing inks, such as a metal halide lamp, xenon lamp, carbon arc lamp, chemical lamp, low-pressure mercury lamp, high-pressure mercury lamp, UV-LED lamp, etc., can be used.

[0059] Active energy ray curable inkjet inks contain an active energy ray polymerizable compound as a dispersion medium. Examples of such polymerizable compounds include monofunctional polymerizable compounds or polymerizable compounds having two or more polymerizable groups (hereinafter referred to as "polyfunctional polymerizable compounds"). Here, a polymerizable group means a group having a polymerizable unsaturated double bond.

[0060] The monofunctional polymerizable compound described above is preferably a compound that has polymerizable unsaturated double bonds and is liquid at 25°C, with a molecular weight of 60 to 2000, and more preferably 100 to 1000. Furthermore, the viscosity of such a monofunctional polymerizable compound is preferably 1000 mPa·s or less, and more preferably 300 mPa·s or less. The viscosity is preferably 1 mPa·s or more, and more preferably 3 mPa·s or more.

[0061] Examples of monofunctional polymerizable compounds include compounds having a heterocyclic structure, monofunctional (meth)acrylates having a linear or cyclic aliphatic group, monofunctional (meth)acrylates having an alkylene oxy group, monofunctional (meth)acrylates having an aromatic hydrocarbon group, and monovinyl ether compounds.

[0062] Examples of compounds having a heterocyclic structure include N-vinylcaprolactam, N-vinylpyrrolidone, (meth)acryloylmorpholine, N-(meth)acryloyloxyethylhexahydrophthalimide, tetrahydrofurfuryl(meth)acrylate, and cyclic trimethylolpropaneformal(meth)acrylate. Among these, N-vinylcaprolactam is preferred because it is safe, readily available and relatively inexpensive, and provides good curability and adhesion of the cured coating film to the recording medium.

[0063] Examples of monofunctional (meth)acrylates having a linear or cyclic aliphatic group include isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isomiristyl (meth)acrylate, isostearyl (meth)acrylate, tricyclodecanedimethanol mono(meth)acrylate, adamantyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate.

[0064] Examples of monofunctional (meth)acrylates having an alkylene oxy group include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-ethylhexyl diglycol (meth)acrylate, diethylene glycol mono (meth)acrylate, diethylene glycol monobutyl ether (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypropylene glycol (meth)acrylate.

[0065] Examples of monofunctional (meth)acrylates having aromatic hydrocarbon groups include 2-phenoxyethyl (meth)acrylate and benzyl (meth)acrylate. Among these, 2-phenoxyethyl (meth)acrylate is preferred, and 2-phenoxyethyl acrylate is more preferred from the viewpoint of inkjet ejectability, adhesion of the resulting coating film after curing, and flexibility (stretch resistance) at low temperatures.

[0066] The polyfunctional polymerizable compounds described above may be monomers, oligomers, or polymers. In this specification, "monomer" refers to a compound with a molecular weight (or weight-average molecular weight, if a molecular weight distribution exists) of 1000 or less. The molecular weight (or weight-average molecular weight, if a molecular weight distribution exists) of monomers is 50 to 1000. "Oligomer" generally refers to a polymer having a finite number of constituent units (generally 5 to 100) based on monomers, with a weight-average molecular weight exceeding 1000 and less than 30000. "Polymer" refers to a polymer with a weight-average molecular weight of 30000 or more. The weight-average molecular weight is measured by gel permeation chromatography (GPC) and is the value obtained as a standard polystyrene equivalent.

[0067] Examples of polyfunctional polymerizable compounds include polyfunctional (meth)acrylates, divinyl ether compounds or trivinyl ether compounds, urethane (meth)acrylates or amino (meth)acrylates. Examples of polyfunctional (meth)acrylates include compounds similar to the two- or more functional polyfunctional (meth)acrylate compounds mentioned above, which undergo a Michael addition reaction with polyfunctional thiols to form mercapto-modified (meth)acrylates (a). Examples of divinyl ether compounds or trivinyl ether compounds include ethylene 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, cyclohexanedimethanol divinyl ether, trimethylolpropane trivinyl ether, etc. Examples of urethane (meth)acrylates include aliphatic urethane (meth)acrylates and aromatic urethane (meth)acrylates. The weight-average molecular weight of the urethane (meth)acrylate is preferably 1,000 to 30,000, and more preferably 2,000 to 20,000.

[0068] Amino(meth)acrylate is an amine-modified (meth)acrylate having an amino group. The number-average molecular weight of amino(meth)acrylate is preferably 2,000 to 20,000, more preferably 2,000 to 10,000, and even more preferably 2,000 to 5,000. Commercially available amino(meth)acrylate can also be used, for example, EBECRYL7100 and EBECRYL80 manufactured by Daicel Ornex.

[0069] If the ink further contains other polymerizable compounds, these other polymerizable compounds may be present individually or in combination of two or more. The amount of other polymerizable compounds varies depending on the performance to be imparted to the ink, but is generally preferably in the range of 50 to 75% by mass, and more preferably in the range of 60 to 70% by mass.

[0070] The photopolymerization initiator (b) in the ink is an acylphosphine compound (b-1) and the following general formula (1) (In the formula, R １ R represents a hydrogen atom or an alkyl group. ２ (where represents a hydrogen atom, an alkyl group, or an acyl group.) Preferably, it is at least one selected from the group consisting of phosphinic acid ester compounds (b-2) represented by ).

[0071] Examples of acylphosphine compounds (b-1) include 2-methylbenzoyldiphenylphosphine oxide, bis(2,6-dichlorobenzoyl)phenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide. The acylphosphine compound (b-1) may be contained in the ink as a single compound or as two or more compounds.

[0072] In the phosphinic acid ester compound (b-2) represented by general formula (1), the alkyl groups represented by R1 and R2 are preferably C1 to C6 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, and hexyl groups. The acyl group represented by R2 is preferably a C1 to C20 acyl group such as an acetyl, propionyl, or benzoyl group. Among these, the benzoyl group is preferred. Such an acyl group may be further substituted with one or more substituents.

[0073] Examples of phosphinate ester compounds (b-2) include methyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, methyl (3-benzoyl-2,4,6-trimethylbenzoyl)phenylphosphinate, ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)phenylphosphinate, and isopropyl pivaloylphenylphosphinate. One type of phosphinate ester compound (b-2) may be contained in the ink, or two or more types may be contained in the ink.

[0074] When considering the use of an ultraviolet light-emitting diode (UV-LED) light source as the source of active energy rays, the acylphosphine compound (b-1) as the photopolymerization initiator (b) corresponding to the wavelength of light emitted from the UV-LED light source is preferably phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide or 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Furthermore, the phosphinic acid ester compound (b-2) as the photopolymerization initiator (b) is preferably ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate or ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)phenylphosphinate.

[0075] The photopolymerization initiator (b), selected from the group consisting of acylphosphine compounds (b-1) and phosphinic acid ester compounds (b-2), may be contained in the ink as one type or as two or more types. When two or more photopolymerization initiators (b) are contained, two or more acylphosphine compounds (b-1) may be contained, two or more phosphinic acid ester compounds (b-2) may be contained, or one or more acylphosphine compounds (b-1) and one or more phosphinic acid ester compounds (b-2) may be contained.

[0076] Other photopolymerization initiators, distinct from the acylphosphine compound (b-1) and the phosphinic acid ester compound (b-2), may be further included. Examples of such other photopolymerization initiators include benzoin isobutyl ether, 2,4-diethylthioxanthone [also known as 2,4-diethylthioxanthene-9-one], 2-isopropylthioxanthone, methylbenzoyl formate, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 1-hydroxycyclohexylphenyl ketone, benzoin ethyl ether, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropane-1-one, and 1-(4-isopropylphenyl)-2-H Examples include droxy-2-methylpropan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4'-methyldiphenyl sulfide, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-morpholinophenyl)-butan-1-one), 1-{4-[(4-benzoylphenyl)sulfanyl]phenyl}-2-methyl-2-[(4-methylphenyl)sulfonyl]propan-1-one, etc.

[0077] The content of the photopolymerization initiator (b) relative to the ink is preferably 0.1 to 15% by mass, and more preferably 2 to 14% by mass, from the viewpoint of improving the curability of the ink, the storage stability of the ink composition, suppressing discoloration of the formed coating film, and improving the performance of the coating film. Furthermore, if other photopolymerization initiators described above are used in addition to the acylphosphine compound (b-1) and phosphinic acid ester compound (b-2) as the photopolymerization initiator (b), the total amount of these is preferably 0.1 to 15% by mass, and more preferably 2 to 14% by mass, relative to the ink.

[0078] In addition to the components described above, the ink according to this embodiment may further optionally contain polymerization inhibitors such as hydroquinone, di-t-butylhydroquinone, p-methoxyphenol, benzoquinone, dibutylhydroxytoluene, nitrosamine salts, hindered amine compounds, and 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). If a polymerization inhibitor is included, the amount is preferably in the range of 0.01 to 2% by mass relative to the ink.

[0079] Printed materials can be manufactured by using an inkjet recording device to eject energy-ray curable ink onto a substrate, which is the recording medium, and then curing it by irradiating it with active energy rays. Examples of printed materials include advertisements, signs, information boards, and promotional materials.

[0080] Energy ray curing inkjet inks offer excellent adhesion to a variety of substrates used as recording media, making it easy to print on surfaces with curved or uneven, irregular shapes.

[0081] For example, a plastic substrate can be used as the base material. Specifically, examples of plastic substrates include ABS (acrylonitrile butadiene styrene) resin, PVC (polyvinyl chloride) / ABS resin, PA (polyamide) / ABS resin, PC (polycarbonate) / ABS resin, PBT (polybutylene terephthalate) / ABS and other ABS-based polymer alloys used as general-purpose injection molding plastics, AAS (acrylonitrile acrylic rubber styrene) resin, AS (acrylonitrile styrene) resin, AES (acrylonitrile ethylene rubber styrene) resin, MS ((meth)acrylic acid ester styrene) resin, PC (polycarbonate) resin, acrylic resin, methacrylic resin, PP (polypropylene) resin, and the like.

[0082] Furthermore, as the plastic substrate, it is also possible to use, for example, thermoplastic resin films used for packaging materials. Examples of thermoplastic resin films include those generally used for food packaging, such as polyethylene letephthalate (PET) film, polystyrene film, polyamide film, polyacrylonitrile film, polyethylene film (LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film), polyolefin films such as polypropylene film (CPP: unoriented polypropylene film, OPP: biaxially oriented polypropylene film), polyvinyl alcohol film, and ethylene-vinyl alcohol copolymer film. As for the thermoplastic resin film, it is also possible to use films that have been stretched, such as uniaxially or biaxially stretched, or films that have been treated with flame treatment or corona discharge treatment on their surface.

[0083] The present invention will be described in detail below with reference to examples, but the content of the present invention is not limited thereto. The raw materials used in the examples are as follows: [1] C.I. Pigment Yellow 185 PY185-1: C.I. Pigment Yellow 185 (manufactured by SunChemical) The physical properties of PY185-1 are as shown in Table 1.

[0084] The measurement methods for each item in Table 1 are as follows: (Average particle diameter) The particle diameter (major and minor diameters) was measured as follows: 5 mg of C.I. Pigment Yellow 185 was added to 4 mL of cyclohexanone and dispersed for 10 minutes using an ultrasonic cleaner (product name "Bransonic M2800-J", manufactured by Yamato Scientific Co., Ltd.). The resulting dispersion was dropped onto a mesh (collodion membrane attached, 200 mesh, manufactured by Nisshin EM Co., Ltd.) to prepare a measurement sample. The measurement sample was photographed using an electron microscope (product name "JEM-1400Flash", manufactured by JEOL Ltd.), and the major and minor diameters of 100 primary pigment particles in the obtained photograph were measured using ImageJ (image processing software), and the average value (arithmetic mean) was calculated.

[0085] (Average Aspect Ratio) The average aspect ratio was calculated as "average value of major axis / average value of minor axis". (Specific Surface Area) For 200 mg of C.I. Pigment Yellow 185, the specific surface area was calculated by measuring the amount of gas (nitrogen) adsorbed using the single-point method with a fully automatic specific surface area measuring device Macsorb HM model-1208 (manufactured by Mountec Co., Ltd.).

[0086] [2] Compound (B) and metal sulfonate salt (C) represented by general formula (i) [Preparation Example 1] Preparation of a mixture of compound (B1) and metal sulfonate salt (C1) (Mixture 1)

[0087] First, 550 parts by mass of 3,3'-dichlorobenzidine dihydrochloride (100% solids) was added to 1500 parts by mass of water under stirring, and at the same time, 680 parts by mass of 35% hydrochloric acid was added. Next, ice and water were added to adjust the temperature to below 0 degrees Celsius and to a volume that allowed the contents to be thoroughly stirred. Then, 769 parts by mass of 40% sodium nitrite was added to diazotize the mixture. After removing the excess nitrite with sulfamic acid, the mixture was filtered to obtain a diazo solution containing bisdiazonium salt.

[0088] Separately, 810 parts by mass of acetoacetate anilide and 207 parts by mass of the potassium salt of p-sulfoacetoacetate anilide were dispersed in 7000 parts by mass of water, and dissolved with 20% by mass of caustic soda to obtain a coupler solution. 80% by mass of acetic acid was added to this coupler solution while diluting with water to adjust the pH to weakly acidic. Then, at a temperature of 0°C to 5°C, the diazo solution obtained above was added dropwise to the coupler solution to carry out a coupling reaction, thereby synthesizing compound (i-1, C.I. Pigment Yellow 12) and the potassium salt of compound (ii-1).

[0089] After raising the temperature of the reaction solution to 40°C, 40 parts by mass of aluminum sulfate were added and the mixture was stirred for 1 hour. The temperature was then raised to 80°C and held for 1 hour. The reaction solution was filtered through a Nutsche filter, and the filtrate was washed with 40,000 parts by mass of water to obtain the wet material. This was dried in a forced-air dryer at 100°C for 24 hours and then pulverized to obtain a mixture (mixture 1) of compound (i-1, C.I. Pigment Yellow 12) [compound (B1)] and aluminum sulfonate salt derived from the above compound (ii-1) [compound (C1)]. When mixture 1 was analyzed by liquid chromatography, the peak area ratio of compound B1 to compound C1 was 2:1. Furthermore, compounds containing the structure formed by the reaction of one molecule of bisdiazonium salt and two molecules of the potassium salt of p-sulfoacetoacetate anilide (the anion represented by the above formula (iii-1)) were below the detection limit.

[0090] [Preparation Example 2] Preparation of a mixture of compound (B2) and metal sulfonate salt (C2) (Mixture 2)

[0091] First, 550 parts by mass of 3,3'-dichlorobenzidine dihydrochloride (100% solids) was added to 1500 parts by mass of water under stirring, and at the same time, 680 parts by mass of 35% hydrochloric acid was added. Next, ice and water were added to adjust the liquid volume so that the temperature would be below 0 degrees Celsius and the contents would be thoroughly stirred. Then, 769 parts by mass of 40% sodium nitrite was added to diazotize the mixture. After removing the excess nitrite with sulfamic acid, the mixture was filtered to obtain a diazo solution containing bisdiazonium salt.

[0092] Separately, 810 parts by mass of acetoacetate-m-xylide and 207 parts by mass of the potassium salt of p-sulfoacetoacetate anilide were dispersed in 7,000 parts by mass of water, and dissolved with 20% by mass of caustic soda to obtain a coupler solution. 80% by mass of acetic acid was added to this coupler solution while diluting with water to adjust the pH to weakly acidic. Then, at a temperature of 0°C to 5°C, the diazo solution obtained above was added dropwise to the coupler solution to carry out a coupling reaction, thereby synthesizing compound (i-2) and the potassium salt of compound (ii-2).

[0093] After raising the temperature of the reaction solution to 40°C, 40 parts by mass of aluminum sulfate were added and the mixture was stirred for 1 hour. The temperature was then raised to 80°C and held for 1 hour. The reaction solution was filtered through a Nutsche filter, and the filtrate was washed with 40,000 parts by mass of water to obtain the wet material. This was dried in a forced-air dryer at 100°C for 24 hours and then pulverized to obtain a mixture (mixture 2) of compound (i-2) [compound (B2)] and aluminum sulfonate salt derived from compound (ii-2) [compound (C2)]. When mixture 2 was analyzed by liquid chromatography, the peak area ratio of compound (B2) to compound (C2) was 2:1. Furthermore, compounds containing the structure formed by the reaction of one molecule of bisdiazonium salt and two molecules of the potassium salt of p-sulfoacetoacetate anilide (the anion represented by the above formula (iii-1)) were below the detection limit.

[0094] [Preparation Example 3] Preparation of a mixture of compound (B3) and metal sulfonate salt (C3) (Mixture 3)

[0095] First, 550 parts by mass of 3,3'-dichlorobenzidine dihydrochloride (100% solids) was added to 1500 parts by mass of water under stirring, and at the same time, 680 parts by mass of 35% hydrochloric acid was added. Next, ice and water were added to adjust the temperature to below 0 degrees Celsius and to a volume that allowed the contents to be thoroughly stirred. Then, 769 parts by mass of 40% sodium nitrite was added to diazotize the mixture. After removing the excess nitrite with sulfamic acid, the mixture was filtered to obtain a diazo solution containing bisdiazonium salt. Separately, 755 parts by mass of acetoacetate-o-toluide and 207 parts by mass of the potassium salt of p-sulfoacetoacetate anilide were dispersed in 7000 parts by mass of water, and dissolved with 20% by mass of caustic soda to obtain a coupler solution. 80% by mass of acetic acid was added to this coupler solution while diluting it with water to adjust the pH to weakly acidic. Subsequently, the diazo solution obtained above was added dropwise to the coupler solution at a temperature of 0°C to 5°C to carry out a coupling reaction, thereby synthesizing the potassium salts of compound (i-3) and compound (ii-3).

[0096] After raising the temperature of the reaction solution to 40°C, 40 parts by mass of aluminum sulfate were added and the mixture was stirred for 1 hour. The temperature was then raised to 80°C and held for 1 hour. The reaction solution was filtered through a Nutsche filter, and the filtrate was washed with 40,000 parts by mass of water to obtain the wet material. This was dried in a forced-air dryer at 100°C for 24 hours and then pulverized to obtain a mixture (mixture 3) of compound (i-3) [compound (B3)] and aluminum sulfonate salt derived from compound (ii-3) [compound (C3)]. When mixture 3 was analyzed by liquid chromatography, the peak area ratio of compound (B3) to compound (C3) was 2:1. Furthermore, compounds containing the structure formed by the reaction of one molecule of bisdiazonium salt and two molecules of the potassium salt of p-sulfoacetoacetate anilide (the anion represented by the above formula (iii-1)) were below the detection limit.

[0097] - Liquid chromatography conditions: High-performance liquid chromatography (product name "EXTREMA", manufactured by JASCO Corporation) was used. Specifically, 25 mg of the sample to be measured and 100 mL of dimethyl sulfoxide (manufactured by Kanto Chemical Co., Ltd.) were weighed into a 100 mL volumetric flask, dispersed in an ultrasonic disperser for 30 minutes, and then shaken by hand for 1 minute. After that, the sample to be measured was filtered through a 0.45 μm filter (manufactured by ADVANTECH) and the filtrate was collected into a sample bottle and measured using EXTREMA. The abundance of each compound was then calculated from the obtained peak area values. [HPLC Measurement Conditions] Column: SHISEIDO CAPCELL PAK C 18 UG 120, C18, 3 μm, 4.6 × 100 mm Eluent 1: Acetonitrile Eluent 2: 1 vol% Dibutylammonium Acetate Aqueous Solution Gradient: Acetonitrile 0% → 60 min → 100% (Hold for 10 minutes) Flow Rate: 0.4 mL / min Oven: 50°C Wavelength: 400 nm Injection Volume: 1.0 μL

[0098] <Examples 1-9, Comparative Examples 1 and 2> [1] Pigment Compositions Pigment compositions 1-11 were prepared by mixing C.I. Pigment Yellow 185 and the mixtures 1-3 obtained above in the proportions shown in Table 2 below. The mixing was carried out by loading the materials into a drum mixer (KRT-50, manufactured by Kato Riki Seisakusho Co., Ltd.) and mixing for 3 hours. In Comparative Example 2, C.I. Pigment Yellow 12 (manufactured by DIC Corporation) was used as compound (i-1).

[0099] Furthermore, the pH of the pigment compositions listed in Table 2 was measured according to the method described in JIS K 5101-17-1:2004.

[0100] [2] UV-curing inkjet ink (UVIJ ink) 4.00 g of the pigment composition obtained above, 4.57 g of dispersant (BYKJET-9150, BYK-Chemie GmbH), 31.43 g of UV monomer (dipropylene glycol diacrylate, Miramer M222, MIWON), and zirconia beads (YTZ balls, φ0.5 mm, Nikkatoh) were placed in a 100 mL poly bottle (wide-mouth bottle, manufactured by Teraoka Co., Ltd.) and shaken in a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 2 hours. After that, the zirconia beads were separated with a mesh to obtain a UV pigment dispersion.

[0101] Next, in a 100 mL poly bottle, add 15.00 g of the UV pigment dispersion obtained above, 23.28 g of preheated and mixed UV monomer (hexanediol diacrylate, Laromer HDDA, manufactured by BASF Corporation), 8.96 g of UV monomer (isobornyl acrylate, IBOA, manufactured by Nippon Shokubai Co., Ltd.), 2.10 g of photopolymerization initiator (phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, Omnirad 819, manufactured by IGM RESINS B.V.), 0.49 g of photopolymerization initiator (2,4-diethylthioxanthene-9-one, Omnirad DETX, manufactured by IGM RESINS B.V.), and polymerization inhibitor (quinone-based gelling inhibitor, Irgastab UV 22. 0.18 g of BASF Corporation's product was added and shaken in a paint shaker for 10 minutes to obtain UVIJ ink.

[0102] The viscosity (initial and after storage) and volume-average dispersed particle size (Mv) (initial and after storage) of the obtained UVIJ ink were measured, and the results are shown in Table 3. The measurement methods for each are as follows: [Measurement of UVIJ ink viscosity (initial and after storage)] The viscosity (initial) of the UVIJ ink manufactured above was measured using an E-type viscometer TV-25 (manufactured by Toki Sangyo Co., Ltd.) at 20°C and 30 rpm. The UVIJ ink manufactured above was then stored for one week in a constant temperature oven at 50°C (multi-safety type dryer MSO-45TPH, manufactured by Futaba Chemical Co., Ltd.), and the viscosity (after storage) of the UVIJ ink was measured in the same manner. The change in viscosity was then calculated.

[0103] [Measurement of Volume-Average Dispersed Particle Size (Mv) of UVIJ Ink (Initial and After Storage)] First, 0.05 g of the UVIJ ink prepared above was diluted with 10 mL of methyl ethyl ketone, and the volume-averaged dispersed particle size (initial) was measured using a concentrated particle size analyzer FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.). Then, the UVIJ ink prepared above was stored for one week in a constant temperature oven at 50°C (multi-safety type dryer MSO-45TPH, manufactured by Futaba Chemical Co., Ltd.), and the volume-averaged dispersed particle size (after storage) of the UVIJ ink was measured in the same manner. The change in volume-averaged dispersed particle size was then calculated.

[0104] The UVIJ inks of Examples 1 to 9 exhibit lower viscosity and smaller volume-average dispersed particle size compared to the comparative example inks that do not contain compound (B) and / or compound (C). Furthermore, the same trend is observed even after storage, indicating that the inks of the examples also possess excellent storage stability. Therefore, the inks according to the embodiments of the present invention have advantages such as low viscosity, small dispersed particle size, and excellent storage stability. Using such inks enables cleaner printing, and the small dispersed particle size prevents clogging of the inkjet printer nozzle head.

[0105] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

Claims

1. (A) C.I. Pigment Yellow 185, and (B) a compound represented by the following general formula (i), [In general formula (i), R ｉ１ ~R ｉ１０ Each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have substituents. ] (C) A metal sulfonic acid salt comprising a cation part and an anion part, wherein the cation part contains a metal ion and the anion part comprises a structure represented by the following general formula (ii), and [In general formula (ii), R ｉｉ１ ~R ｉｉ５ Each of these independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may have substituents. A pigment composition comprising [ 2. R in the above general formula (i) ｉ１ ~R ｉ１０ The pigment composition according to claim 1, wherein each is independently a hydrogen atom or a methyl group.

3. R ​​in the above general formula (ii) ｉｉ１ ~R ｉｉ５ The pigment composition according to claim 1 or 2, wherein each is independently a hydrogen atom or a methyl group.

4. The metal ion in the sulfonic acid metal salt (C) is selected from the group consisting of aluminum ion (Al ３＋ ), sodium ion (Na ＋ ), potassium ion (K ＋ ), calcium ion (Ca ２＋ ), and barium ion (Ba ２＋ ), and the pigment composition according to any one of claims 1 to 3.

5. The pigment composition according to any one of claims 1 to 4, wherein the compound (B) represented by the general formula (i) is contained in a proportion of 0.1 to 20% by mass based on 100% by mass of the pigment composition.

6. The pigment composition according to any one of claims 1 to 5, wherein the metal sulfonate salt (C) is contained in a proportion of 0.1 to 10% by mass based on 100% by mass of the pigment composition.

7. The pigment composition according to any one of claims 1 to 6, wherein the content ratio (mass ratio) of the compound (B) represented by the general formula (i) and the metal sulfonate salt (C) is (B):(C) = 1:10 to 10:

1.

8. The pigment composition according to any one of claims 1 to 7, wherein the pH is 4.0 or higher.

9. A pigment dispersion comprising the pigment composition according to any one of claims 1 to 8 and a dispersion medium.

10. The pigment dispersion according to claim 9, further comprising a dispersant.

11. An ink comprising the pigment dispersion according to claim 9 or 10.

12. The ink according to claim 11, which is an active energy ray curable inkjet ink.

13. The ink according to claim 11 or 12, wherein the viscosity (at 20°C) is 17.5 mPa·s or less.

14. The ink according to any one of claims 11 to 13, wherein the volume-average dispersed particle diameter (Mv) is 200 nm or less.

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