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

Abstract

According to one embodiment, a pigment composition is provided that includes CI Pigment Yellow 180 and a compound represented by the following general formula (1). [Formula 1] TIFF0007841659000020.tif47154

Description

Technical Field

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

Background Art

[0002] Conventionally, pigments have been mainly used for coloring inks, paints, toners, rubbers, and plastics, mass coloring of synthetic fibers, pigment printing, coloring of miscellaneous goods, etc. Among these, printing applications such as inks play an important role in industry. For example, gravure inks, flexo inks, etc. are widely used for the purpose of imparting cosmetic properties and functionality to the printed object of a flexible packaging film. In recent years, with the spread of inkjet printers, there has been an increasing expectation for the development of inkjet inks having more excellent performance.

[0003] Inkjet printers are not only used for home use but also widely deployed for industrial use in response to the trend of small-lot printing, and in recent years, the business has expanded to textile applications and soft packaging applications of packages. Currently, aqueous inks are becoming the mainstream as inks for inkjet printers, and pigments used in such inks are required to have performances such as coloring power, light resistance, and easy dispersibility.

[0004] For example, yellow ink is generally a major color ink together with cyan, magenta, and black inks. As yellow pigments constituting yellow ink, conventionally, C.I. Pigment Yellow 74 (hereinafter also referred to as "PY74") having high coloring power, C.I. Pigment Yellow 155 (hereinafter also referred to as "PY155") having high light resistance, etc., have been often used (for example, Patent Documents 1 and 2). However, PY74 has a problem of poor light resistance, and PY155 has a problem of low coloring power, and C.I. Pigment Yellow 180 (hereinafter also referred to as "PY180") having an excellent balance between coloring power and light resistance has been attracting attention as a new yellow pigment.

[0005] However, PY180 has the problem of poor dispersibility in dispersion media, and there is a need for the development of easily dispersible PY180 compositions and pigment dispersions, inks, etc., with excellent dispersibility of PY180. Furthermore, diligent research is being conducted to obtain desirable performance (for example, appropriate viscosity, print density (OD), lightfastness, storage stability, etc.) depending on the application (for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2009-179722 [Patent Document 2] Japanese Patent Publication No. 2009-67866 [Patent Document 3] Patent No. 6984791 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Against the background described above, there is a need for a PY180 composition with even more desirable properties. The present invention aims to provide a PY180 composition that can obtain a pigment dispersion with excellent properties such as gloss value, dispersion stability, and viscosity. [Means for solving the problem]

[0008] As a result of diligent research, the inventors have discovered that by using PY180 in combination with a predetermined compound, a pigment dispersion with excellent properties such as gloss value, dispersion stability, and viscosity can be obtained. The present invention is as follows, for example. [1] A pigment composition comprising CI Pigment Yellow 180 and a compound represented by the following general formula (1): [ka] [In general formula (1), S t 1 and S t2 Each independently represents a group selected from the group consisting of the following formulas (S t 1 / 2 -1) to (S t 1 / 2 -4);

Chemical formula

[0009] According to the present invention, it is possible to provide a PY180 composition that yields a pigment dispersion with excellent properties such as gloss value, dispersion stability, and viscosity. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described in detail below. According to one embodiment, the pigment composition of the present invention comprises CI Pigment Yellow 180 and a compound represented by the following general formula (1). [ka] [In general formula (1), S t 1 and S t 2 Each of these independently corresponds to the following equation (S t 1 / 2 -1)~(S t 1 / 2 Represents a group selected from the group consisting of (-4); [ka] (Formula(S t 1 / 2 -1)~(S t 1 / 2 -4) Medium, The wavy lines represent the bonding sites with the NH group in the general formula (1) above; X 1 (Each of these independently represents a hydrogen atom or a metal ion.) However, S t 1 and S t 2 However, both are formula (S t 1 / 2 It will never represent -1).

[0011] As a result of diligent research, the inventors have found that by using PY180 in combination with the compound represented by the above general formula (1), a pigment dispersion with excellent properties such as gloss value, dispersion stability, and viscosity can be obtained. 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. The reason why the above-mentioned desirable properties can be obtained by including the compound represented by the above general formula (1) together with PY180 is not clear, but it is presumed that by adding the compound represented by the above general formula (1) which has a functional group, electrostatic repulsion in water increases, allowing the dispersed state to be maintained, and consequently improving dispersibility. Furthermore, with compounds that have a different parent skeleton from the compound represented by the above general formula (1), adsorption to the pigment surface decreases, and sufficient dispersibility and stability may not be obtained. In water, the adsorption method to the pigment surface is mainly π-π stacking. Therefore, it is presumed that the addition of a compound represented by the above general formula (1), which has a benzene ring as its parent skeleton and a functional group, would be effective.

[0012] The following describes in detail the components, manufacturing methods, physical properties, and applications of the pigment composition, pigment dispersion, and ink according to the embodiment. In this application, PY180 does not simply mean a compound having the structure shown below, but rather a pigment composed of said compound. The concept of said pigment includes not only substances characterized by their crystalline structure, but also substances characterized by the physical properties of aggregates and / or aggregates arising from the primary particles formed by aggregation and / or aggregation of said pigment, and further from the surface state thereof.

[0013] [Pigment composition] [1] CI Pigment Yellow 180 (PY180) PY180 is a yellow pigment identified by CAS No. 77804-81-0 and represented, for example, by the following chemical formula. The pigment composition according to the embodiment only needs to contain at least PY180 as a coloring agent, and may also contain pigments or dyes other than PY180 to the extent that it does not impair the effects of the present invention. [ka]

[0014] PY180 can be obtained, for example, by coupling a bisdiazonium salt solution obtained by adding an aqueous sodium nitrite solution to 1,2-bis(2-aminophenoxy)-ethane in the presence of a strong acid under ice-cold conditions, and then reacting the solution with 5-acetoacetylamino-benzimidazolone. Commercially available PY180 can 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 the 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 pigments. 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 the print density (OD). Furthermore, the average particle diameter (major axis) of PY180 is preferably a value such that the average value of the average aspect ratio and minor axis falls within the above range, 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 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 using the formula "average particle diameter (major diameter) / average particle diameter (minor diameter)".

[0016] The specific surface area of ​​PY180 is preferably 40 to 90 m² from the viewpoint of ink fluidity and coloring power. 2 / g, more preferably 45-80m 2 The value is / g. The specific surface area is calculated based on the amount of gas (nitrogen) adsorbed using the single-point method, as described in the examples below. PY180 is preferably included in a proportion of 60.0 to 99.9% by mass, more preferably 80.0 to 99.9% by mass, and particularly preferably 85.0 to 99.0% by mass, 90.0 to 99.0% by mass, or 95.0 to 99.0% by mass, based on 100% by mass of the pigment composition. The above range of PY180 content results in superior dispersion stability and coloring power.

[0017] Furthermore, the proportion of PY180 with an aspect ratio of 1.00 to 4.00 in the pigment composition is preferably 50% by mass or more (e.g., 50 to 100% by mass), more preferably 70% by mass or more (e.g., 70 to 100% by mass), and particularly preferably 80% by mass or more (e.g., 80 to 100% by mass) or 95% by mass or more (e.g., 95 to 100% by mass). A better effect can be obtained by having the proportion of PY180 with an aspect ratio of 1.00 to 4.00 within the above range.

[0018] [2] Compound of formula (1) The pigment composition according to the embodiment contains one or more compounds represented by the following general formula (1). Compounds represented by general formula (1) are azo-hydrazo tautomers and therefore may contain both azo (-N=N-) and hydrazo (>N-NH-) forms. [ka]

[0019] In general formula (1), S t 1 and S t 2 Each of these independently corresponds to the following equation (S t1 / 2 -1)~(S t 1 / 2 -4) represents a group selected from the group, t 1 and S t 2 However, both are formula (S t 1 / 2 -1) is never represented. [ka] The wavy lines represent the bonding sites with the NH group in the general formula (1) above. Also, X 1 Each of these independently represents a hydrogen atom or a metal ion. 1 If is a metal ion, the other parts can appropriately act as counterions. For example, equation (S t 1 / 2 -2)~(S t 1 / 2 -4) -SO3, -COO, -O are -SO3 - , -COO - , -O - It can exist as such. S t 1 and S t 2 At least one of them is given by formula (S t 1 / 2 It is more preferable that the group is represented by -2) (where X 1 It is especially preferable that it is H). Formula (S t 1 / 2 -1)~(S t 1 / 2 -4) In X 1 Each of these independently represents either 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+ Examples include aluminum ions (Al 3+ ) is preferable. X1 From the viewpoint of dispersion stability, it is preferable that it be a hydrogen atom.

[0020] Specifically, compounds represented by the general formula (1) are those represented by the following structural formulas (1-1) to (1-6). [ka]

[0021] Here, if the metal ion is a polyvalent ion, the bonding state is not certain, but it is thought that the polyvalent ion is bonded intramolecularly or intermolecularly with the heteroatoms (oxygen atom, nitrogen atom) in the general formula (1). In other words, if 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. The pigment composition according to the embodiment preferably contains, as a compound represented by general formula (1), the compound represented by structural formula (1-1) and / or the compound represented by structural formula (1-2), and more preferably the compound represented by structural formula (1-2), from the viewpoint of dispersion stability and solubility.

[0022] The compound represented by general formula (1) is preferably included in a proportion of 0.1% by mass or more, 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% or 4.0 to 10.0% by mass, based on 100% by mass of the pigment composition. Furthermore, the compound represented by general formula (1) is preferably included in a proportion 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, based on 100 parts by mass of PY180. The inclusion of the compound represented by general formula (1) in such amounts results in superior dispersion stability and coloring power.

[0023] [3] Other ingredients The pigment composition according to the embodiment may contain yellow pigments or dyes in addition to PY180 as a pigment component. Examples of yellow pigments include azo, disazo, azomethine, anthraquinone, quinophthalone, benzimidazolon, isoindoline, quinacridone, and perinone pigments, and more specifically, CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 23, 24, 34, 35, 37, 5 Examples include 3, 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, 213, etc. In addition, dyes and pigments other than these yellow pigments may be included. In the pigment composition according to the embodiment, the proportion of PY180 in the total pigments contained in the composition is preferably 60% by mass or more, more preferably 70% by mass or more.

[0024] 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.

[0025] 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 state of the mixture of the pigment composition is not particularly limited.

[0026] [Pigment dispersion] Another embodiment of the present invention provides a pigment dispersion 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.

[0027] 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 mixing using a dispensing machine. The mixing state of the pigment dispersion is not particularly limited. PY180 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.

[0028] The pigment dispersion may further contain a dispersant. Such a dispersant can be any agent that disperses PY180, 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. As a dispersant, a polymer having structural units derived from a styrene compound and structural units derived from a maleic acid compound is preferred from the viewpoint of dispersion stability. Examples of styrene compounds include styrene, vinylbenzoic acid, and methylstyrene. Examples of maleic acid compounds include maleic acid, maleic anhydride, and phenylmaleic anhydride.

[0029] The weight-average molecular weight (Mw) of the dispersant is preferably 3,000 to 20,000, and more preferably 10,000 to 15,000, from the viewpoint of wettability and dispersion stability. The weight-average molecular weight (Mw) of the dispersant can be calculated by measuring it using a gel permeation chromatography (GPC) instrument under the following conditions and then converting it using polystyrene as a standard substance. Equipment: HLC-8220GPC (manufactured by Tosoh Corporation) Columns: Connect the following columns in series. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (Differential Refractometer) Column temperature: 40℃ Eluent: Tetrahydrofuran (THF) Flow rate: 1.0ml / 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] The acid value of the dispersant is preferably 5 to 20 mg KOH / g, and more preferably 7 to 15 mg KOH / g, from the viewpoint of dispersion stability. 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 mg KOH / g or less, and more preferably 5 mg KOH / 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% 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, and surfactants. 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.

[0031] The pigment dispersion according to the embodiment has a gloss value of preferably 60° or higher, more preferably 60 to 90°, and particularly preferably 65 to 85°. A gloss value of this magnitude allows for higher dispersibility. Furthermore, the pigment dispersion according to the embodiment has a viscosity of preferably 1 to 20 mPa·s, more preferably 1.5 to 10 mPa·s, and particularly preferably 2 to 6 mPa·s. In addition, the pigment dispersion according to the embodiment has a volume-average dispersed particle diameter (Mv), an indicator of dispersion stability, of preferably 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〕 In further embodiments, 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 viewpoint of producing less waste liquid and not requiring a printing plate. Of the inkjet inks, aqueous inkjet ink is preferred from the viewpoint of environmental impact and odor. The ink according to the embodiment is manufactured by adding and mixing a dispersion medium and additives commonly used in the art to the pigment dispersion described above. 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 can be mixed by methods commonly used in the art, but examples include mixing methods using a dispensing machine.

[0033] 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. The ratio of additives 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 PY180 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.

[0034] The ink according to this embodiment preferably contains substantially no alkali metal hydroxides, which may degrade the SiO2 material of the inkjet head. Here, "substantially" means intentionally omitting them, and the content is, for example, less than 1% by mass of the total ink amount.

[0035] The viscosity of the ink according to the embodiment (at 20°C) is preferably 1 to 30 mPa·s, more preferably 2 to 20 mPa·s, 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 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. The ink according to the embodiment has a volume-average dispersed particle diameter (Mv) value, which is an indicator of dispersion stability, preferably 80 to 250 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm. Viscosity and volume-average dispersed particle diameter (Mv) can be measured by the method described in the examples below.

[0036] If 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 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.

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

[0038] 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] CI Pigment Yellow 180 CI Pigment Yellow 180 (PY180) listed 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.) [Table 1]

[0039] The measurement methods for each item in Table 1 are as follows: (Average particle size) 5 mg of CI Pigment Yellow 180 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 axes of 100 primary pigment particles in the obtained 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 of major axis / average of minor axis". (specific surface area) For CI Pigment Yellow 180 200 mg, the specific surface area was calculated by measuring the amount of gas (nitrogen) adsorbed using a single-point method with a fully automated specific surface area analyzer, Macsorb HM model-1208 (manufactured by Mountec Co., Ltd.).

[0040] [Synthesis example A] 225 parts by mass of 1,2-bis(2-aminophenoxy)-ethane was dispersed in 3300 parts by mass of water, then 538.5 parts by mass of 35% hydrochloric acid was added. While maintaining the temperature below 5°C with ice, 337 parts by mass of 40% sodium nitrite aqueous solution was added dropwise to prepare the diazo component. Next, 455 parts by mass of 5-acetoacetylamino-benzimidazolone was dispersed in 3400 parts by mass of water, then 595 parts by mass of 25% sodium hydroxide aqueous solution was added and dissolved to obtain the coupler component. The diazo component and coupler component were adjusted to 6500 parts by mass and 4500 parts by mass, respectively, by adding water and ice. 30.6 parts by mass of 90% acetic acid was added to 6500 parts by mass of water, and the temperature of this solution was adjusted to 20°C. Then, the coupler component was added dropwise to adjust the pH to 6.0, and the diazo component was added dropwise at a constant rate. To prevent the presence of excess diazonium salt in the acetic acid solution, the addition of the coupler component was started simultaneously with the addition of the diazo solution, and the coupling was performed while adjusting the addition rate of the coupler component to adjust the pH of the acetic acid solution to 6.0. During coupling, ice or 5% by mass sodium hydroxide solution was added as needed to maintain a temperature of 20°C and a pH of 6.0. After the coupling was completed in about 3 hours, the mixture was heated to 90°C and held for 1 hour. The wet cake obtained by filtration and washing with water was then dried at 90°C. The resulting solid was crushed 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 placed in a 15 L Trimix™ (manufactured by Inoue Seisakusho Co., Ltd.). The mixture was ground for 5 hours while maintaining an internal temperature of 80°C to 100°C. The ground material was then added to 50°C warm water, stirred, and thoroughly reslurred. After filtration and washing with water, the resulting wet cake was dried at 90°C. The resulting solid was crushed in a juicer mixer to obtain PY180-2.

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

[0043] (Preparation of diazo components) 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% hydrochloric acid was added. Then, while maintaining the temperature below 5°C by adding ice, 18.1 parts by mass of 40% sodium nitrite aqueous solution was added dropwise to obtain the diazo component. Separately, 11.6 parts by mass of potassium 4-(acetoacetylamino)benzenesulfonate was dissolved in 150 parts by mass of water to prepare a solution, and the entire solution was added dropwise to the diazo component obtained above at a constant rate.

[0044] (Preparation of coupler components 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 25% by mass of sodium hydroxide aqueous solution was added to dissolve it and obtain a coupler component. Water and ice were added to the obtained coupler component to adjust the volume to 500 parts by mass. Separately, 1.6 parts by mass of 90% acetic acid was added to 660 parts by mass of water, and then the temperature of this acetic acid solution was adjusted to 20°C.

[0045] (Coupling reaction) The coupler component prepared above was added dropwise to the acetic acid solution prepared above, and after adjusting the pH to 6.0, the dropwise addition of the diazo component was started at a constant rate. To ensure that no excess diazonium salt was present in the acetic acid solution, the addition of the coupler component was started simultaneously with the addition of the diazo solution. The coupling reaction was carried out while maintaining the pH at 6.0 by adjusting the addition rate of the coupler component. During the coupling reaction, the system was cooled as needed or a 5% by mass sodium hydroxide solution was added to maintain a temperature of 20°C and a pH of 6.0, and the coupling reaction was carried out over 3 hours. After the coupling reaction, the system was heated to 90°C and held for 1 hour. Next, the wet cake was filtered, washed with water, and dried at 90°C. The obtained solid was crushed in a juicer mixer to obtain product 1. Product 1 was analyzed by liquid chromatography and found that the CI pigment yellow ratio was 180 / compound(1-1) / compound(1-2) = 13.4 / 37.4 / 49.2.

[0046] [Synthesis Example 2] [ka]

[0047] (Preparation of diazo components) The diazo component was prepared in the same manner as in Synthesis Example 1. (Preparation of coupler components and acetic acid solution) 30.7 parts by mass of potassium 4-(acetoacetylamino)benzenesulfonate was dissolved in a mixture of 31.3 parts by mass of 25% by mass sodium hydroxide aqueous 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 adjusted to 20°C.

[0048] (Coupling reaction) The coupling reaction was carried out in the same manner as in Synthesis Example 1, and subsequent steps such as filtration, washing, drying, and grinding were also performed in the same manner as in Synthesis Example 1. As a result, Product 2 was obtained. Product 2 was analyzed by liquid chromatography and found that the CI pigment yellow ratio was 180 / compound(1-1) / compound(1-2) = 0.0 / 100.0 / 0.0.

[0049] [Synthesis Example 3] [ka]

[0050] Product 3 was obtained by following the same procedure 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 "dissolving 8.7 parts by mass of N-(2-carboxyphenyl)-3-oxobutanamide and 10.0 parts by mass of 25% by mass of sodium hydroxide in 150 parts by mass of water to prepare a solution". Product 3 was analyzed by liquid chromatography and found that the CI pigment yellow ratio was 180 / compound(1-3) / compound(1-4) = 4.0 / 0.0 / 96.0.

[0051] [Synthesis Example 4] [ka]

[0052] Product 4 was obtained by following the same procedure 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 "dissolving 9.4 parts by mass of 5-acetoacetylamino-2-hydroxybenzoic acid and 10.0 parts by mass of 25% by mass of sodium hydroxide in 150 parts by mass of water to prepare a solution". Product 4 was analyzed by liquid chromatography and found that the CI pigment yellow ratio was 180 / compound(1-5) / compound(1-6) = 3.3 / 56.4 / 40.3.

[0053] • Analysis method using liquid chromatography Liquid chromatography (product name "Agilent 1100," manufactured by Agilent Technologies, Inc.) was used. Specifically, 5 mg of each sample (products 1-4) 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 using a shaker (product name "VORTEX-GENIE2", manufactured by Scientific Industries). Next, the mixture was mixed for 1 hour at 130 rpm while maintaining a temperature of 25°C in a constant temperature shaker (product name "PERSONAL-11," manufactured by Taitec Co., Ltd.). Subsequently, the measurement samples (products 1-4) were filtered through a 0.45 μm filter (ADVANTECH) and transferred to 2 ml sample bottles, which were then placed in an Agilent 1100 for measurement. Then, the amount of each compound was calculated from the obtained area values.

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

[0055] <Examples 1-11, Comparative Example 1> [1] Pigment dispersion Pigment compositions 1 to 12 were prepared by mixing CI Pigment Yellow 180 with products 1 to 4 obtained above in the proportions shown in Table 2 below. Mixing was performed by placing CI Pigment Yellow 180 and the products in a vial and shaking it by hand. [Table 2]

[0056] To each of the obtained pigment compositions 1 to 12, 2.0 g of a dispersant (DISPERBYK-190, manufactured by Bic Chemie, polyether-modified styrene-maleic anhydride copolymer, MW: approximately 11,000, acid value: 10 mg KOH / g, amine value: 0 mg KOH / g) and 14.0 g of deionized water were added to obtain a mixture totaling 20.0 g. 0.5 mm zirconia beads were added to the resulting mixture and dispersed using paint conditioner for 90 minutes. Subsequently, ion-exchanged water was added to produce a pigment dispersion with a pigment content (PY180 and compounds (1-1) to (1-6)) of 12.5% ​​by mass.

[0057] The gloss value, viscosity, and volume-average dispersion particle size (Mv) of the obtained pigment dispersion were evaluated. The evaluation methods for each are as follows. (Gloss value) The pigment dispersion was applied to OK Topcoat S (manufactured by Oji Paper Co., Ltd.) using a bar coater (RD SPECIALTIES, No. 6). Then, the gloss value of the colored layer was measured using a gloss meter (BYK Gardner haze gloss meter) under conditions of an incident angle of 60 degrees and a reflection angle of 60 degrees. (viscosity) The measurements were taken using an E-type viscometer, model TV-25 (manufactured by Toki Sangyo Co., Ltd.), under conditions of 20°C and 30 rpm. (Volume-average dispersion particle size: Mv) The volume-average dispersion particle size (Mv) of the pigment dispersion was measured using a particle size distribution analyzer (Nanotrac WAVEII, manufactured by Microtrac-Bel). The pigment dispersion was diluted with pure water so that the loading index was in the range of 8 to 12 before measurement.

[0058] [2] Inkjet ink To the pigment dispersions obtained above (9.6 g each), 0.3 g of Surfinol 465 (manufactured by Nisshin 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 deionized water were added to produce an inkjet ink with a total volume of 30.0 g. The viscosity and volume-average dispersed particle size (Mv) of the obtained inkjet ink were evaluated. The method was the same as that used for evaluating the pigment dispersion. Table 3 shows the evaluation results for the pigment dispersion and inkjet ink. [Table 3]

[0059] The pigment dispersions and inkjet inks of Examples 1 to 11 exhibited higher gloss values ​​and lower volume-average dispersion particle sizes compared to comparative examples that did not contain the compound of formula (1). Furthermore, they showed good viscosity values. Therefore, the pigment dispersions and inks according to these embodiments possess superior properties compared to conventional materials, particularly in terms of dispersion stability and, consequently, storage stability.

[0060] 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 pigment composition comprising C.I. Pigment Yellow 180 and a compound represented by the following general formula (1): 【Chemistry 1】 [In general formula (1), S ｔ １ and S ｔ ２ Each of these independently gives the following equation (S ｔ １／２ -1) ~ (S ｔ １／２ Represents a group selected from the group consisting of -4); 【Chemistry 2】 (Formula (S)) ｔ １／２ -1)~(S) ｔ １／２ -4) Middle The dashed line represents the bonding site with the NH group in the general formula (1) above; X １ (Each of these independently represents a hydrogen atom or a metal ion.) However, S ｔ １ and S ｔ ２ However, both are formula (S ｔ １／２ -1) will never be expressed.

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

3. The pigment composition according to claim 1, wherein the compound represented by the general formula (1) is contained in a proportion of 0.1% by mass or more based on 100% by mass of the pigment composition.

4. The pigment composition according to claim 1, wherein the average aspect ratio of the C.I. Pigment Yellow 180 is 1.0 to 4.

0.

5. The pigment composition according to claim 1, wherein the compound represented by the general formula (1) is selected from the group consisting of compounds represented by the following formulas (1-1) to (1-6). 【Transformation 3】

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 according to 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 comprising the pigment dispersion described in claim 6.

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