Pigment composition, and pigment dispersion and ink containing same

Abstract

One embodiment of the present invention provides a pigment composition comprising C.I. Pigment Yellow 180 and a compound represented by general formula (1).

Description

Pigment composition, and pigment dispersion and ink containing the same

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

[0002] Traditionally, pigments have been used primarily in inks, paints, toners, coloring rubber and plastics, dyeing synthetic fibers with concentrates, pigment textile printing, coloring miscellaneous goods, and the like. In particular, printing applications such as inks play an important industrial role. For example, gravure inks and flexographic inks are widely used to impart aesthetic beauty and functionality to printed substrates such as flexible packaging films. Furthermore, with the recent widespread use of inkjet printers, expectations are rising for the development of inkjet inks with superior performance.

[0003] Inkjet printers are not only used for home use, but are also widely used in industry due to the trend towards smaller print runs, and in recent years the business has expanded to include textile applications and flexible packaging. Currently, water-based inks are becoming the mainstream for inkjet printers, and the pigments used in these inks are required to have properties such as coloring strength, lightfastness, and ease of dispersibility.

[0004] For example, yellow ink, along with cyan, magenta, and black inks, is generally a major color ink. Conventionally, C.I. Pigment Yellow 74 (hereinafter also referred to as "PY74"), which has high coloring power, and C.I. Pigment Yellow 155 (hereinafter also referred to as "PY155"), which has high lightfastness, have been frequently used as yellow pigments for yellow ink (see, for example, Patent Documents 1 and 2). However, PY74 has problems such as poor lightfastness, and PY155 has low coloring power. Therefore, C.I. Pigment Yellow 180 (hereinafter also referred to as "PY180"), which has an excellent balance of coloring power and lightfastness, has been attracting attention as a new yellow pigment.

[0005] However, PY180 has a problem of poor dispersibility in a dispersion medium, and there is a demand for the development of a PY180 composition that is easily dispersible, and for pigment dispersions, inks, etc. that have excellent dispersibility of PY180. In addition, extensive research has been conducted to obtain preferable performance depending on the application (for example, appropriate viscosity, printing density (OD), lightfastness, storage stability, etc.) (for example, Patent Document 3).

[0006] JP 2009-179722 A JP 2009-67866 A Japanese Patent No. 6984791

[0007] Under the circumstances described above, there is a demand for a PY180 composition having more preferable properties. An object of the present invention is to provide a PY180 composition that can provide a pigment dispersion having excellent properties such as gloss value, dispersion stability, and viscosity.

[0008] As a result of extensive research, the present inventors have found that a pigment dispersion excellent in properties such as gloss value, dispersion stability, and viscosity can be obtained by using PY180 in combination with a predetermined compound. The present invention is, for example, as follows. [1] A pigment composition comprising C.I. Pigment Yellow 180 and a compound represented by the following general formula (1): [In general formula (1), S ｔ １ and S ｔ ２ are each independently represented by the following formula (S ｔ １／２ -1) to (S ｔ １／２ -4) represents a group selected from the group consisting of: (Formula (S ｔ １／２ -1) to (S ｔ １／２ In formula (1), the wavy line represents a bonding site with the NH group; １ each independently represents a hydrogen atom or a metal ion), provided that S ｔ １ and S ｔ ２ Both are expressions (S ｔ １／２ -1). [2] X １represents a hydrogen atom. [3] The pigment composition according to [1] or [2], wherein the compound represented by the general formula (1) is contained in an amount of 0.1% by mass or more relative to 100% by mass of the pigment composition. [4] The pigment composition according to any one of [1] to [3], wherein the C.I. Pigment Yellow 180 has an average aspect ratio of 1.0 to 4.0. [4-1] The pigment composition according to any one of [1] to [4], wherein the C.I. Pigment Yellow 180 has an average particle diameter (minor axis) of 30 to 150 nm. [4-2] The pigment composition according to any one of [1] to [4-1], wherein the C.I. Pigment Yellow 180 has an average particle diameter (major axis) of 30 to 250 nm. [4-3] The pigment composition according to any one of [1] to [4-1], wherein the C.I. Pigment Yellow 180 has a specific surface area of ​​40 to 90 m ２ / g. [4-4] The pigment composition according to any one of [1] to [4-3], wherein the C.I. Pigment Yellow 180 is contained in an amount of 60.0 to 99.9% by mass, relative to 100% by mass of the pigment composition. [5] The pigment composition according to any one of [1] to [4-4], wherein the compound represented by general formula (1) is selected from the group consisting of compounds represented by the following formulas (1-1) to (1-6): [6] A pigment dispersion comprising the pigment composition according to any one of [1] to [5] and a dispersion medium. [7] The pigment dispersion according to [6], further comprising a dispersant. [8] The pigment dispersion according to [7], wherein the dispersant is a polymer having structural units derived from a styrene compound and structural units derived from a maleic acid compound. [8-1] The pigment dispersion according to any one of [6] to [8], wherein the pigment dispersion contains the pigment composition and the dispersion medium in a ratio of 1:3 to 1:10 (mass ratio). [8-2] The pigment dispersion according to any one of [6] to [8-1], wherein the pigment dispersion contains PY180 in an amount of 5 to 30 mass% relative to 100 mass% of the pigment dispersion. [8-3] The pigment dispersion according to any one of [7] to [8-2], wherein the pigment dispersion contains the dispersant in an amount of 0.5 to 10 mass% in terms of solid content relative to 100 mass% of the pigment dispersion. [8-4] The pigment dispersion according to any one of [6] to [8-3], wherein the pigment dispersion has a gloss value of 60° or more. [8-5] The pigment dispersion according to any one of [6] to [8-4], wherein the pigment dispersion has a viscosity of 1 to 20 mPa s. [8-6] The pigment dispersion according to any one of [6] to [8-5], wherein the pigment dispersion has a volume average dispersed particle diameter (Mv) of 80 to 200 nm. [9] An ink comprising the pigment dispersion according to any one of [6] to [8-3].

[0009] According to the present invention, it is possible to provide a PY180 composition that can provide a pigment dispersion that is excellent in properties such as gloss value, dispersion stability, and viscosity.

[0010] Hereinafter, embodiments of the present invention will be described in detail. According to one embodiment, the pigment composition of the present invention contains C.I. Pigment Yellow 180 and a compound represented by the following general formula (1): [In general formula (1), S ｔ １ and S ｔ ２ are each independently represented by the following formula (S ｔ １／２ -1) to (S ｔ １／２ -4) represents a group selected from the group consisting of: (Formula (S ｔ １／２-1) to (S ｔ １／２ In formula (1), the wavy line represents a bonding site with the NH group; １ each independently represents a hydrogen atom or a metal ion), provided that S ｔ １ and S ｔ ２ Both are expressions (S ｔ １／２ -1).

[0011] As a result of extensive research, the present inventors have discovered that the combined use of PY180 and a compound represented by the general formula (1) results in a pigment dispersion with excellent properties such as gloss, dispersion stability, and viscosity. These properties are particularly beneficial when the PY180 composition or its pigment dispersion is used as an ink (e.g., an inkjet ink). Generally, a high gloss value tends to correlate with high pigment dispersibility, and low viscosity also contributes to improved dispersibility. While the reason why the inclusion of a compound represented by the general formula (1) together with PY180 results in the aforementioned favorable properties is unclear, it is speculated that the addition of a compound represented by the general formula (1) having a functional group increases electrostatic repulsion in water, allowing the dispersion state to be maintained, resulting in improved dispersibility. Furthermore, compounds with a different backbone from the compound represented by the general formula (1) may have reduced adsorption to the pigment surface, resulting in insufficient dispersibility and stability. In water, adsorption to the pigment surface is primarily via π-π stacking. Therefore, it is presumed that the addition of a compound having a benzene ring as the main skeleton and a functional group, which is represented by the above general formula (1), is effective.

[0012] The constituent elements, manufacturing methods, physical properties, applications, etc. of the pigment composition, pigment dispersion, and ink according to the embodiments are described in detail below. In this application, PY180 does not simply refer to a compound having the structure shown below, but refers to a pigment composed of this compound. The concept of this pigment not only includes substances characterized by their crystal structure, but also by the physical properties of the aggregates and / or aggregates formed by aggregation and / or aggregation of these primary particles, and the aggregates and / or aggregates resulting from the surface condition, etc.

[0013] [Pigment composition] [1] C.I. Pigment Yellow 180 (PY180) PY180 is identified by CAS No. 77804-81-0 and is a yellow pigment represented, for example, by the following chemical formula. The pigment composition according to the embodiment only needs to contain at least PY180 as a colorant, and may also contain pigments or dyes other than PY180 as long as the effects of the present invention are not impaired.

[0014] PY180 can be obtained, for example, by adding an aqueous sodium nitrite solution to 1,2-bis(2-aminophenoxy)-ethane in the presence of a strong acid under ice-cooling conditions, and then coupling the resulting bisdiazonium salt solution with 5-acetoacetylamino-benzimidazolone. Commercially available PY180 may be used as is, and examples of commercially available products include "SYMULER FAST YELLOW BY 2000GT" (manufactured by DIC Corporation). The pigment composition according to this embodiment may contain one or more types of PY180. Since PY180 is an azo-hydrazo tautomer, it may contain both the azo form (-N=N-) and the hydrazo form (>N-NH-).

[0015] The average aspect ratio (major axis / minor axis) of PY180 is preferably 1.00 to 4.00, more preferably 1.50 to 3.80, from the viewpoint of suppressing aggregation of pigment particles. The average particle diameter (minor axis) of PY180 is preferably 30 to 150 nm, more preferably 35 to 100 nm, and particularly preferably 40 to 65 nm or 40 to 60 nm, from the viewpoint of increasing print density (OD). The average particle diameter (major axis) of PY180 is preferably such that the average aspect ratio and the average value of the minor axis fall within the above-mentioned ranges, but is preferably 30 to 250 nm, more preferably 50 to 220 nm, and particularly preferably 80 to 210 nm or 50 to 150 nm. The average particle diameter (major axis, minor axis) can be measured by image analysis using an electron microscope, as described in the Examples below, and the average aspect ratio can be calculated using the formula "average particle diameter (major axis) / average particle diameter (minor axis)".

[0016] The specific surface area of ​​PY180 is preferably 40 to 90 m from the viewpoint of ink fluidity and coloring power. ２ / g, more preferably 45 to 80 m ２ / g. The specific surface area is calculated based on the gas (nitrogen) adsorption amount by the single-point method, as described in the Examples below. PY180 is contained in an amount of preferably 60.0 to 99.9 mass%, more preferably 80.0 to 99.9 mass%, and particularly preferably 85.0 to 99.0 mass%, 90.0 to 99.0 mass%, or 95.0 to 99.0 mass%, relative to 100 mass% of the pigment composition. When the content of PY180 is within the above range, the dispersion stability and coloring power are more excellent.

[0017] Furthermore, the proportion of PY180 having an aspect ratio of 1.00 to 4.00 in the pigment composition is preferably 50% by mass or more (for example, 50 to 100% by mass), more preferably 70% by mass or more (for example, 70 to 100% by mass), and particularly preferably 80% by mass or more (for example, 80 to 100% by mass) or 95% by mass or more (for example, 95 to 100% by mass). When the proportion of PY180 having an aspect ratio of 1.00 to 4.00 is within the above range, more excellent effects can be obtained.

[0018] [2] Compound of Formula (1) The pigment composition according to this embodiment contains one or more compounds represented by the following general formula (1): The compound represented by general formula (1) is an azo-hydrazo tautomer, and therefore may contain both an azo form (-N=N-) and a hydrazo form (>N-NH-).

[0019] In general formula (1), S ｔ １ and S ｔ ２ are each independently represented by the following formula (S ｔ １／２ -1) to (S ｔ １／２ -4), wherein S ｔ １ and S ｔ ２ Both are expressions (S ｔ １／２ -1) is not represented. The wavy line represents the bonding site with the NH group in the general formula (1). １ Each of X independently represents a hydrogen atom or a metal ion. １ When is a metal ion, other moieties may be suitable counter ions. For example, ｔ １／２ -2) ~ (S ｔ １／２ -SO in -4) ３ , -COO, -O is -SO ３ － , -COO － , -O － etc. ｔ １ and S ｔ ２ At least one of the formula (S ｔ １／２ It is more preferable that the group is a group represented by the formula (wherein X １ is particularly preferably H). ｔ １／２ -1) to (S ｔ １／２ -4) In X １Each of the symbols independently represents a hydrogen atom or a metal ion. Examples of metal ions include sodium ions (Na ＋ ), potassium ions (K ＋ ), calcium ions (Ca ２＋ ), barium ions (Ba ２＋ ), aluminum ions (Al ３＋ ), but from the viewpoint of solubility and dispersion stability, aluminum ions (Al ３＋ ) is preferred. １ is preferably a hydrogen atom from the viewpoint of dispersion stability.

[0020] As the compound represented by the general formula (1), specifically, compounds represented by the following structural formulas (1-1) to (1-6) are preferred.

[0021] Here, when the metal ion is a polyvalent ion, the bonding state is not clear, but it is thought that the polyvalent ion is bonded intramolecularly or intermolecularly to the heteroatom (oxygen atom, nitrogen atom) in the general formula (1). In other words, when the metal ion is a polyvalent ion, it can take on a structure in which multiple structures represented by the above formula (1) are associated. From the viewpoints of dispersion stability and solubility, the pigment composition according to the embodiment preferably contains, as the compound represented by general formula (1), a compound represented by structural formula (1-1) and / or a compound represented by structural formula (1-2), and more preferably contains a compound represented by structural formula (1-2).

[0022] The compound represented by general formula (1) is preferably contained in an amount of at least 0.1% by mass, more preferably 0.1 to 15.0% by mass, even more preferably 0.5 to 15.0% by mass, and particularly preferably 0.5 to 10% by mass or 4.0 to 10.0% by mass, relative to 100 parts by mass of the pigment composition. Furthermore, the compound represented by general formula (1) is preferably contained in an amount of 0.5 to 15.0 parts by mass, more preferably 4.0 to 14.0 parts by mass, and particularly preferably 6.0 to 13.0 parts by mass, relative to 100 parts by mass of PY180. By containing the compound represented by general formula (1) in such an amount, dispersion stability and tinting power are improved.

[0023] [3] Other Components The pigment composition according to the embodiment may contain a yellow pigment or dye as a pigment component in addition to PY180. Examples of yellow pigments include azo-based, disazo-based, azomethine-based, anthraquinone-based, quinophthalone-based, benzimidazolone-based, isoindoline-based, quinacridone-based, and perinone-based pigments, and more specifically, C.I. Pigment Yellow 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, 185, and 213. Furthermore, dyes and pigments other than these yellow pigments may be contained. In the pigment composition according to this embodiment, the proportion of PY180 in all pigments contained in the composition is preferably 60% by mass or more, and more preferably 70% by mass or more.

[0024] The pigment composition according to the embodiment may further contain other components that are typically 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.

[0025] The pigment composition according to the embodiment can be produced by mixing the above-described components. The mixing can be carried out by a method commonly used in the art, such as a method of blending using a mixer. The mixed state of the pigment composition is not particularly limited.

[0026] [Pigment Dispersion] According to another embodiment of the present invention, a pigment dispersion is provided that includes 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. The dispersion medium can be selected from materials commonly used in the art as long as they are capable of dispersing the pigment composition. Examples of the dispersion medium 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. A mixture of water and an organic solvent may also be used.

[0027] In the pigment dispersion, the pigment composition and the dispersion medium are mixed preferably in a mass ratio of 1:3 to 1:10, more preferably 1:6 to 1:8. Mixing can be performed by a method commonly used in the art, such as a mixing method using a disperser. The mixed state of the pigment dispersion is not particularly limited. PY180 is preferably contained in a proportion of 5 to 30 mass%, more preferably 8 to 15 mass%, relative to 100 mass% of the pigment dispersion.

[0028] The pigment dispersion may further contain a dispersant. Such dispersants may be any dispersant capable of dispersing PY180, and examples thereof 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. From the viewpoint of dispersion stability, the dispersant is preferably a polymer having a structural unit derived from a styrene compound and a structural unit derived from a maleic acid compound. Examples of styrene compounds include styrene, vinylbenzoic acid, and methylstyrene. Examples of maleic acid compounds include maleic acid, maleic anhydride, and phenylmaleic anhydride.

[0029] From the viewpoint of wettability and dispersion stability, the weight average molecular weight (Mw) of the dispersant is preferably 3,000 to 20,000, and more preferably 10,000 to 15,000. The weight average molecular weight (Mw) of the dispersant can be calculated by measuring under the following conditions using a gel permeation chromatography (GPC) apparatus and converting the value using polystyrene as a standard substance. Apparatus: HLC-8220GPC (manufactured by Tosoh Corporation) Column: The following columns were connected in series: "TSKgel G5000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G4000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G3000" (7.8 mm I.D. x 30 cm) x 1, "TSKgel G2000" (7.8 mm I.D. x 30 cm) x 1 Detector: RI (differential refractometer) Column temperature: 40°C Eluent: tetrahydrofuran (THF) Flow rate: 1.0 ml / min Injection volume: 100 μL (THF solution with a sample concentration of 0.4% by mass) Standard sample: monodisperse polystyrene (TSKgel, manufactured by Tosoh Corporation) "A-500", "A-1000", "A-2500", "A-5000", "F-1", "F-2", "F-4", "F-10", "F-20", "F-40", "F-80", "F-128", "F-288", "F-550"

[0030] From the viewpoint of dispersion stability, the acid value of the dispersant is preferably 5 to 20 mgKOH / g, more preferably 7 to 15 mgKOH / g. The acid value can be measured and calculated in accordance with JIS K 0070. From the viewpoint of dispersion stability, the amine value of the dispersant is preferably 20 mgKOH / g or less, more preferably 5 mgKOH / g or less. The amine value can be measured and calculated in accordance with ASTM D2074. The amount of dispersant added is preferably 0.5 to 10 mass%, more preferably 1 to 5 mass%, in terms of solids content, relative to 100 mass% of the pigment dispersion. The pigment dispersion may contain additives other than the dispersant. Examples of such additives include preservatives, pH adjusters, water-soluble polymers, water-dispersible resins, surfactants, etc. The amount of other additives added is preferably 0 to 30 mass%, more preferably 0 to 15 mass%, relative to 100 mass% of the pigment dispersion.

[0031] The pigment dispersion according to the embodiment preferably has a gloss value of 60° or more, more preferably 60 to 90°, and particularly preferably 65 to 85°. Such a gloss value enables higher dispersibility to be achieved. Furthermore, the pigment dispersion according to the embodiment preferably has a viscosity of 1 to 20 mPa·s, more preferably 1.5 to 10 mPa·s, and particularly preferably 2 to 6 mPa·s. Furthermore, the pigment dispersion according to the embodiment preferably has a volume-average dispersed particle diameter (Mv), which is an index of dispersion stability, of 80 to 200 nm, more preferably 100 to 170 nm, and particularly preferably 100 to 150 nm. The gloss value, viscosity, and volume-average dispersed particle diameter (Mv) can be measured by the methods described in the examples below.

[0032] [Ink] According to a further embodiment, an ink containing a pigment dispersion is provided. The type of ink is not particularly limited, but examples include gravure ink, flexographic ink, and inkjet ink. Among these, inkjet ink is preferred from the viewpoints of small waste volume and the absence of printing plates. From the viewpoints of environmental impact and odor, the inkjet ink is preferably an aqueous inkjet ink. The ink according to the embodiment is produced by adding and mixing a dispersion medium and additives commonly used in the relevant field to the above-mentioned pigment dispersion. The dispersion medium for the ink is not particularly limited, but examples include the same dispersion medium as described for the pigment dispersion. The mixing method is also not particularly limited, and mixing can be performed by a method commonly used in the relevant field, such as a mixing method using a disperser.

[0033] The ink may contain additives commonly used in the relevant field as needed. Examples of such additives include preservatives, pH adjusters, chelating agents, rust inhibitors, water-soluble UV absorbers, water-soluble polymer compounds, antioxidants, water-dispersible resins, and surfactants. Examples of surfactants include anionic, cationic, nonionic, amphoteric, silicone-based, and fluorine-based surfactants. In the case of aqueous inks, water or a water-soluble organic solvent may be added to adjust the ink concentration. The proportion of additives relative to the total mass of the ink according to this embodiment (the total amount when two or more additives are included) is preferably 0 to 30% by mass, more preferably 0 to 15% by mass. PY180 is preferably contained in an amount of 2 to 10% by mass, and more preferably 3 to 5% by mass, relative to 100% by mass of ink.

[0034] The ink according to the embodiment is made of SiO, which is the material of the inkjet head. ２ It is preferable that the ink is substantially free of alkali metal hydroxides, which may deteriorate the ink. Here, "substantially" means that the ink is intentionally free of alkali metal hydroxides, and the content of alkali metal hydroxides is, for example, less than 1% by mass of the total amount of the ink.

[0035] The viscosity (20°C) of the ink according to the embodiment is preferably 1 to 30 mPa·s, more preferably 2 to 20 mPa·s, and particularly preferably 2 to 10 mPa·s, or 4 mPa or less (for example, 2 to 4 mPa·s or 2 to 3 mPa·s), from the viewpoint of improving the storage stability of the ink. The viscosity of the ink can be measured by the method described in the Examples below. The pH of the ink according to the embodiment is, for example, 7.0 or more, preferably 7.5 or more, from the viewpoint of further improving the storage stability of the ink. Furthermore, from the viewpoints of component resistance and skin irritation, the pH is, for example, 11.0 or less, preferably 10.0 or less. The ink according to the embodiment has a volume average dispersed particle diameter (Mv), which is an index of dispersion stability, of preferably 80 to 250 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm. The viscosity and volume average dispersed particle diameter (Mv) can be measured by the method described in the Examples below.

[0036] When the ink according to the embodiment is an inkjet ink, it can be loaded into a known inkjet recording device and ejected as ink droplets onto a recording medium to record an image, etc. Inkjet recording devices include continuous jet types (charge control types, spray types, etc.) and on-demand types (piezo type, thermal type, electrostatic suction type, etc.), and the ink according to the embodiment can be used with any of these types.

[0037] The ink according to the embodiment can be prepared by appropriately mixing the above-described pigment dispersion with a dispersion medium, additives, etc. The mixing can be performed by a method commonly used in the art, such as a mixing method using a disperser. The mixed state of the ink is not particularly limited.

[0038] The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited thereto. The raw materials used in the examples are as follows. [1] C.I. Pigment Yellow 180 C.I. Pigment Yellow 180 (PY180) shown in Table 1 was used. PY180-1: Pigment obtained in Synthesis Example A PY180-2: Pigment obtained in Synthesis Example B PY180-3: PV FAST YELLOW HG01 (manufactured by Clariant Japan Co., Ltd.) PY180-4: TONER YELLOW HG (manufactured by Clariant Japan Co., Ltd.)

[0039] The measurement methods for each item in Table 1 are as follows. (Average particle size) 5 mg of C.I. Pigment Yellow 180 was added to 4 ml of cyclohexanone and dispersed for 10 minutes in an ultrasonic cleaner (product name "Bransonic M2800-J", manufactured by Yamato Scientific Co., Ltd.). The resulting dispersion was dropped onto a mesh (200 mesh with collodion film attached, manufactured by Nissin 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 axes of 100 primary pigment particles in the photograph were measured using ImageJ (image processing software), and the average value (arithmetic mean) was calculated. (Average aspect ratio) The average aspect ratio was calculated as "average major axis / average minor axis." (Specific surface area) The gas (nitrogen) adsorption amount of 200 mg of C180 was measured by the single-point method using a fully automatic specific surface area measuring device Macsorb HM model-1208 (manufactured by Mountec Co., Ltd.), and the specific surface area was calculated.

[0040] Synthesis Example A: 225 parts by mass of 1,2-bis(2-aminophenoxy)-ethane was dispersed in 3,300 parts by mass of water, and then 538.5 parts by mass of 35% by mass hydrochloric acid was added. While maintaining the temperature at 5°C or below by adding ice, 337 parts by mass of 40% by mass aqueous sodium nitrite solution was added dropwise to prepare a diazo component. Next, 455 parts by mass of 5-acetoacetylamino-benzimidazolone was dispersed in 3,400 parts by mass of water, and 595 parts by mass of 25% by mass aqueous sodium hydroxide solution was added and dissolved to obtain a coupler component. The diazo component and coupler component were prepared by adding water and ice to adjust the liquid volumes to 6,500 parts by mass and 4,500 parts by mass, respectively. 30.6 parts by mass of 90% by mass acetic acid was added to 6,500 parts by mass of water, and the temperature of this solution was adjusted to 20°C. The coupler component was then added dropwise to adjust the pH to 6.0, and then the diazo component was started to be added dropwise at a constant rate. To prevent the presence of excess diazonium salt in the acetic acid solution, the dropwise addition of the coupler component was started simultaneously with the dropwise addition of the diazo solution, and coupling was carried out while adjusting the pH of the acetic acid solution to 6.0 by adjusting the dropwise addition rate of the coupler component. The temperature during coupling was kept at 20°C, and ice or 5% by mass sodium hydroxide solution was added as needed to maintain the pH at 6.0. After completion of coupling in approximately 3 hours, the mixture was heated to 90°C and maintained for 1 hour. The resulting wet cake was then filtered and washed with water, and dried at 90°C. The resulting solid was pulverized in a juicer mixer to obtain PY180-1.

[0041] [Synthesis Example B] 500 parts by mass of PY180-1 obtained in Synthesis Example A, 2500 parts by mass of sodium chloride, and 500 parts by mass of diethylene glycol were charged into a 15 L Trimix (TM; manufactured by Inoue Seisakusho Co., Ltd.), and the temperature was adjusted to maintain the internal temperature at 80°C to 100°C, followed by grinding for 5 hours. The ground product was then added to hot water at 50°C, stirred, and thoroughly reslurried. The resulting wet cake was filtered and washed with water and dried at 90°C. The resulting solid was pulverized using a juicer mixer to obtain PY180-2.

[0042] [2] Compound of Formula (1) The compound of formula (1) was synthesized as follows and used. [Synthesis Example 1]

[0043] (Preparation of Diazo Component) First, 12 parts by mass of 1,2-bis(2-aminophenoxy)-ethane was dispersed in 72 parts by mass of water, and then 28.9 parts by mass of 35% by mass hydrochloric acid was added. Then, while adding ice to maintain the temperature at 5°C or below, 18.1 parts by mass of a 40% by mass aqueous solution of sodium nitrite was added dropwise to obtain a diazo component. Separately, a solution was prepared by dissolving 11.6 parts by mass of potassium 4-(acetoacetylamino)benzenesulfonate in 150 parts by mass of water, and the entire amount of this solution was added dropwise at a constant rate to the diazo component obtained above.

[0044] (Preparation of Coupler Component and Acetic Acid Solution) 13.7 parts by mass of 5-acetoacetylamino-benzimidazolone was dispersed in 218 parts by mass of water, and then 17.7 parts by mass of a 25% by mass aqueous sodium hydroxide solution was added and dissolved to obtain a coupler component. Water and ice were added to the obtained coupler component to adjust the liquid volume to 500 parts by mass. Separately, 1.6 parts by mass of 90% by mass acetic acid was added to 660 parts by mass of water, and the temperature of this acetic acid solution was then adjusted to 20°C.

[0045] (Coupling Reaction) The coupler component prepared above was added dropwise to the acetic acid solution prepared above, and the pH was adjusted to 6.0. The dropwise addition of the diazo component was then initiated at a constant rate. The dropwise addition of the coupler component was initiated simultaneously with the dropwise addition of the diazo solution to prevent the presence of excess diazonium salt in the acetic acid solution. The coupling reaction was carried out while maintaining the pH at 6.0 by adjusting the dropwise addition rate of the coupler component. The coupling reaction was carried out over 3 hours while appropriately cooling or adding 5% by weight sodium hydroxide solution to maintain a temperature of 20°C and a pH of 6.0. After the coupling reaction, the system was heated to 90°C and maintained for 1 hour. The mixture was then filtered and washed with water, and the resulting wet cake was dried at 90°C. The resulting solid was pulverized in a juicer mixer to obtain Product 1. Liquid chromatography analysis of Product 1 revealed a C.I. Pigment Yellow 180 / Compound (1-1) / Compound (1-2) ratio of 13.4 / 37.4 / 49.2.

[0046] Synthesis Example 2

[0047] (Preparation of diazo component) A diazo component was prepared in the same manner as in Synthesis Example 1. (Preparation of coupler component and acetic acid solution) 30.7 parts by mass of potassium 4-(acetoacetylamino)benzenesulfonate was added to and dissolved in a mixed solution of 31.3 parts by mass of 25% by mass aqueous sodium hydroxide solution and 385.6 parts by mass of water to obtain a coupler component. Separately, 1.5 parts by mass of 99% by mass acetic acid was added to 660 parts by mass of water, and the temperature of this acetic acid solution was then adjusted to 20°C.

[0048] (Coupling Reaction) A coupling reaction was carried out in the same manner as in Synthesis Example 1, and the subsequent steps of filtration, washing with water, drying, pulverization, etc. were also carried out in the same manner as in Synthesis Example 1. As a result, Product 2 was obtained. When Product 2 was analyzed by liquid chromatography, it was found that the ratio of C.I. Pigment Yellow 180 / compound (1-1) / compound (1-2) was 0.0 / 100.0 / 0.0.

[0049] Synthesis Example 3

[0050] Product 3 was obtained by performing the same steps as in Synthesis Example 1 (Preparation of Diazo Component), except that the step of "dissolving 11.6 parts by mass of potassium 4-(acetoacetylamino)benzenesulfonate in 150 parts by mass of water to prepare a solution" was changed to a step of "dissolving 8.7 parts by mass of N-(2-carboxyphenyl)-3-oxobutanamide and 10.0 parts by mass of 25% by mass sodium hydroxide in 150 parts by mass of water to prepare a solution." Product 3 was analyzed by liquid chromatography, and the ratio of C.I. Pigment Yellow 180 / compound (1-3) / compound (1-4) was 4.0 / 0.0 / 96.0.

[0051] Synthesis Example 4

[0052] Product 4 was obtained by performing the same steps as in Synthesis Example 1 (Preparation of Diazo Component), except that the step of "dissolving 11.6 parts by mass of potassium 4-(acetoacetylamino)benzenesulfonate in 150 parts by mass of water to prepare a solution" was changed to the step of "dissolving 9.4 parts by mass of 5-acetoacetylamino-2-hydroxybenzoic acid and 10.0 parts by mass of 25% by mass sodium hydroxide in 150 parts by mass of water to prepare a solution." Product 4 was analyzed by liquid chromatography, and the ratio of C.I. Pigment Yellow 180 / compound (1-5) / compound (1-6) was 3.3 / 56.4 / 40.3.

[0053] - Analysis method by liquid chromatography Liquid chromatography (product name "Agilent 1100", manufactured by Agilent Technologies, Inc.) was used. Specifically, 5 mg of the measurement sample (products 1 to 4) and 10 mL of dimethyl sulfoxide (manufactured by Kanto Chemical Co., Ltd.) were weighed into a 30 mL sample bottle and mixed for 10 seconds in a shaker (product name "VORTEX-GENIE2", manufactured by Scientific Industries, Inc.). Subsequently, the mixture was mixed at 130 rpm for 1 hour while maintaining the temperature at 25°C in a thermostatic shaker (product name "PERSONAL-11", manufactured by Taitec Co., Ltd.). Thereafter, the measurement sample (products 1 to 4) was filtered through a 0.45 μm filter (manufactured by ADVANTECH Co., Ltd.) and dispensed into 2 mL sample bottles, which were then placed in the Agilent 1100 for measurement. The amount of each compound present was then calculated from the obtained area value.

[0054] [HPLC equipment conditions] Column: C18 U120 S3 (Φ4.6 mm × 100 mm, 3 μm) Eluent 1: 30 mM ammonium acetate Eluent 2: methanol Gradient (1 / 2): 90 / 10 (up to 3 min), 0 / 100 (up to 40 min), 90 / 10 (up to 50 min) Flow rate: 1.0 mL / min Oven: 50°C Wavelength: 400 nm Injection volume: 1.0 μL

[0055] Examples 1 to 11, Comparative Example 1 [1] Pigment Dispersion Pigment Compositions 1 to 12 were produced by mixing C.I. Pigment Yellow 180 and Products 1 to 4 obtained above in the ratios shown in Table 2 below. The mixing was performed by placing C.I. Pigment Yellow 180 and the products in a vial and shaking them by hand.

[0056] To 4.0 g of each of the obtained pigment compositions 1 to 12, 2.0 g of a dispersant (DISPERBYK-190, manufactured by BYK-Chemie, polyether-modified styrene-maleic anhydride copolymer, MW: approximately 11,000, acid value: 10 mgKOH / g, amine value: 0 mgKOH / g) and 14.0 g of ion-exchanged water were added to obtain a total mixture of 20.0 g. 0.5 mm zirconia beads were added to the obtained mixture, and the mixture was dispersed for 90 minutes using a paint conditioner. Ion-exchanged water was then added so that the pigment content (PY180 and compounds (1-1) to (1-6)) was 12.5% ​​by mass, thereby producing a pigment dispersion.

[0057] The resulting pigment dispersions were evaluated for gloss, viscosity, and volume-average dispersed particle diameter (Mv). The evaluation methods for each were as follows. (Gloss) The pigment dispersions were applied to OK Topcoat S (Oji Paper Co., Ltd.) using a bar coater (RD SPECIALTIES, No. 6). The gloss of the applied layer was measured using a glossmeter (BYK Gardner haze gloss meter) at an incident angle of 60 degrees and a reflection angle of 60 degrees. (Viscosity) Measurements were made using an E-type viscometer TV-25 (Toki Sangyo Co., Ltd.) at 20°C and 30 rpm. (Volume-average dispersed particle diameter: Mv) The volume-average dispersed particle diameter (Mv) of the pigment dispersions was measured using a particle size distribution analyzer (Nanotrac WAVE II, Microtrac Bell). The pigment dispersion was diluted with pure water so that the loading index was in the range of 8 to 12 before the measurement.

[0058] [2] Inkjet ink To the pigment dispersions (9.6 g each) obtained above, 0.3 g of Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.), 1.5 g of 1,2-hexanediol, 1.5 g of 1,2-butanediol, 0.75 g of 3-methoxy-3-methylbutanol, and 16.35 g of ion-exchanged water were added to produce an inkjet ink with a total amount of 30.0 g. The viscosity and volume-average dispersed particle diameter (Mv) of the obtained inkjet ink were evaluated. The evaluation methods were the same as those for the pigment dispersions. The evaluation results of the pigment dispersions and inkjet inks are shown in Table 3.

[0059] It can be seen that the pigment dispersions and inkjet inks of Examples 1 to 11 have higher gloss values ​​and lower volume average dispersed particle diameters than the comparative example that does not contain the compound of formula (1). They also exhibited good viscosity values. Therefore, it can be said that the pigment dispersions and inks according to the embodiments have superior properties compared to conventional ones, and are particularly excellent in dispersion stability, and therefore also in storage stability.

[0060] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

Claims

1. A pigment composition containing C.I. Pigment Yellow 180 and a compound represented by the following general formula (1): [In general formula (1), S ｔ １ and S ｔ ２ are each independently represented by the following formula (S ｔ １／２ -1) to (S ｔ １／２ -4) represents a group selected from the group consisting of: (Formula (S ｔ １／２ -1) to (S ｔ １／２ In formula (1), the wavy line represents a bonding site with the NH group; １ each independently represents a hydrogen atom or a metal ion), provided that S ｔ １ and S ｔ ２ Both are expressions (S ｔ １／２ -1).

2. X １ The pigment composition according to claim 1 , wherein represents a hydrogen atom.

3. The pigment composition according to claim 1 or 2, wherein the compound represented by general formula (1) is contained in an amount of 0.1 mass % or more relative to 100 mass % of the pigment composition.

4. The pigment composition according to any one of claims 1 to 3, wherein the C. I. Pigment Yellow 180 has an average aspect ratio of 1.0 to 4.

0.

5. The pigment composition according to any one of claims 1 to 4, wherein the compound represented by general formula (1) is selected from the group consisting of compounds represented by the following formulas (1-1) to (1-6):

6. A pigment dispersion comprising the pigment composition according to any one of claims 1 to 5 and a dispersion medium.

7. The pigment dispersion of claim 6, further comprising a dispersant.

8. The pigment dispersion according to claim 7, wherein the dispersant is a polymer having structural units derived from a styrene compound and structural units derived from a maleic acid compound.

9. An ink containing the pigment dispersion according to any one of claims 6 to 8.

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