Pigment composition, aqueous pigment dispersion liquid for inkjet ink, and aqueous pigment ink

Abstract

The purpose of the present invention is to provide a pigment composition which has excellent storage stability and dispersion stability and is particularly suitable for use as an aqueous pigment ink for IJ. Specifically, the pigment composition comprises C.I. Pigment Yellow 180 and a derivative having a Zeta potential of-20 mV or more and less than 0 mV and a solubility parameter of 21 or less. It is preferable that the aspect ratio of the C.I. Pigment yellow 180 is 1.0 to 2.0. The derivative is preferably a derivative of C.I. Pigment yellow 180. The derivative preferably has a sulfonic acid group. The trivalent metal in the trivalent metal salt of the derivative is preferably at least one selected from the group consisting of iron, chromium, cobalt and aluminum.

Description

Technical Field

[0001] The present invention relates to a pigment composition containing CI Pigment Yellow 180, an aqueous pigment dispersion liquid for inkjet (hereinafter referred to as "IJ") ink containing the same, and an aqueous pigment ink. Background Art

[0002] IJ printers are not only used at home, but also widely used in industry due to the trend of printing in small batches. In recent years, they have been commercially expanded to textiles and soft packaging. Among them, yellow ink is important as a core ink together with cyan, magenta, and black. In recent years, the mainstream of ink used in IJ printers has become water-based ink, and the pigments used in them are required to have easy dispersibility in water systems in addition to coloring power and light resistance.

[0003] As a yellow pigment for yellow ink, CI Pigment Yellow 180 (hereinafter referred to as "Y180"), which is a type of benzimidazolone yellow pigment, has attracted attention from the viewpoint of achieving both tinting power and light resistance. As an example of using Y180 in IJ ink, for example, the following Patent Document 1 can be cited. Patent Document 1 describes the use of a pigment derivative (amine salt, ammonium salt or monovalent metal salt) such as Y180 containing a sulfonic acid group together with a benzimidazolone yellow pigment such as Y180.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2002-220557 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The present inventors have studied the existing pigment composition containing Y180 in Patent Document 1 and the like, and found that the storage stability and dispersion stability of the pigment composition when used as IJ ink are insufficient. Therefore, the present invention aims to provide a pigment composition having excellent storage stability and dispersion stability, and particularly suitable for use in aqueous pigment ink for IJ.

[0009] Means for solving problems

[0010] The present inventors have conducted intensive studies to solve the above problems and, as a result, have found that a derivative having a specific zeta potential and solubility parameter is used for Y180, thereby completing the present invention. The mechanism of the present invention is as follows.

[0011] Since the Y180 pigment has highly hydrophilic functional groups and binding parts in its molecular structure, it has a tendency to have high wettability to water and good initial dispersion. However, it is speculated that as time goes by, water hinders the interaction between the pigment and the resin, so that the pigment aggregates and causes poor dispersion stability. Therefore, it is considered important to use derivatives to improve the resin adsorption. In general, it is believed that particles with a large absolute value of Zeta potential have high dispersion stability due to electrostatic repulsion, but in the present invention, the dispersion stability is improved by using derivatives with a small absolute value of Zeta potential. This is because, in order to obtain the dispersion stability effect brought by the derivative, it is necessary to adsorb the derivative on the surface of the pigment particles, and the derivative with a large absolute value of Zeta potential cannot be tightly adsorbed on the surface of the pigment particles due to electrostatic repulsion. In addition, by making pigment particles with a small aspect ratio, higher dispersion stability can be obtained. Pigment particles with low dispersion stability and a large aspect ratio are in a rod-like slender shape. In addition, Y180 pigment particles are stacked by π-π stacking, thereby performing particle growth, so the short axis surface of the rod-shaped particles must become a π stacking surface. As the force for the derivative to be adsorbed on the pigment particles, π-π stacking plays a strong role in water, and the π stacking surface of the short axis surface becomes the site of the derivative adsorption. Pigment particles with a large aspect ratio have poor dispersion stability because the long axis surface of the derivative is not adsorbed, and pigment particles with a small aspect ratio have a high area ratio of the short axis surface adsorbed on the derivative, so the dispersion stability effect brought by the derivative is strongly exerted. Regarding pigment particles with a small aspect ratio, if the distance between the short axis surfaces of the two sides in the same pigment particle is considered, since the aspect ratio is small, the distance is close, and the influence between the short axis surfaces is large. As described above, when the derivative is adsorbed on the pigment particles, the electrostatic repulsion of the derivative itself may become an obstacle. Therefore, if you want to make the derivative with a large absolute value of Zeta potential adsorbed on particles with a small aspect ratio, the influence of electrostatic repulsion will be generated between the short axis surfaces of the two sides in the same pigment particle, and the sufficient effect cannot be obtained. Therefore, it is speculated that by combining particles with a small aspect ratio and particles with a small absolute value of Zeta potential, the electrostatic repulsion of the derivative is minimized, and the adsorption of the derivative to the pigment particles is maximized, resulting in a Y180 pigment composition with particularly high dispersion stability.

[0012] As described above, in a pigment with a small aspect ratio, the area ratio of the short axis plane increases, and the derivative is easily adsorbed. However, Y180 with high hydrophilicity also easily adsorbs water. Even if the derivative is adsorbed, water will hinder it, resulting in poor dispersion stability. In addition, in a derivative with a large solubility parameter, the derivative has a high affinity with water, the effect of hindering adsorption to the pigment becomes higher, and the interaction between the pigment and water is enhanced, which is likely to cause poor dispersion. Therefore, it is speculated that by using a derivative with a small solubility parameter to inhibit the derivative from being released from the pigment, and then weakening the interaction between water and the pigment, a Y180 pigment composition with high dispersion stability is obtained.

[0013] That is, the present invention relates to:

[0014] “Item 1. A pigment composition comprising CI Pigment Yellow 180 and a derivative having a zeta potential of greater than -20 mV and less than 0 mV and a solubility parameter of less than 21.

[0015] Item 2. The pigment composition according to Item 1, wherein the aspect ratio of the CI Pigment Yellow 180 is 1.0 to 2.0.

[0016] Item 3. The pigment composition according to Item 1 or 2, wherein the derivative is a derivative of CI Pigment Yellow 180.

[0017] Item 4. The pigment composition according to any one of Items 1 to 3, wherein the derivative has a sulfonic acid group.

[0018] Item 5. The pigment composition according to any one of Items 1 to 4, wherein the derivative is a salt of a trivalent metal, and the trivalent metal is at least one selected from the group consisting of iron, chromium, cobalt, and aluminum.

[0019] Item 6. An aqueous pigment dispersion for inkjet ink, comprising the pigment composition described in any one of Items 1 to 5.

[0020] Item 7. A water-based pigment ink for inkjet, comprising the pigment composition described in any one of Items 1 to 5. ".

[0021] Effects of the Invention

[0022] The pigment composition of the present invention has a small change in viscosity and particle size over time and is excellent in dispersion stability and storage stability. Therefore, it is suitable for use in aqueous IJ inks. DETAILED DESCRIPTION

[0023] Hereinafter, the present invention will be described in detail. In the present invention, Y180 refers not only to the compound shown in the following [Chemical 1], but also to the pigment composed of the compound. The concept of the pigment includes not only its crystal structure, but also its primary particles as aggregates, and the physical properties of the aggregates / aggregates generated by its surface state, etc.

[0024] [Pigment composition]

[0025] The pigment composition of the present invention comprises Y180 and a derivative having a zeta potential of -20 mV or more and less than 0 mV and a solubility parameter of 21 or less. Generally, such a derivative is referred to as a pigment derivative (synergist). In addition to pigments such as Y180 and derivatives, the pigment composition of the present invention may also contain other solid components such as resins for improving dispersibility.

[0026] (pigment)

[0027] Y180 is CAS No. 77804-81-0 and is a yellow pigment represented by the following chemical formula: The pigment composition of the present invention may contain Y180 as a colorant and may contain pigments and dyes other than Y180 within a range that does not impair the effects of the present invention.

[0028] [Chemistry 1]

[0029]

[0030] Y180 can be obtained by the following operation: 1,2-bis(2-aminophenoxy)-ethane is added to an ice-cold aqueous sodium nitrite solution in the presence of a strong acid to carry out a diazotization reaction to obtain a dinitrogen salt solution, and the obtained dinitrogen salt solution is coupled with 5-acetoacetylamino-benzimidazolone.

[0031] The aspect ratio of Y180 is preferably 1.0 to 2.0, more preferably 1.0 to 1.9, and even more preferably 1.0 to 1.8. If the aspect ratio is within this range, the aggregation of pigment particles can be reduced, resulting in a smaller particle size, and when used as an aqueous pigment dispersion / ink for IJ ink, the dispersion stability and storage stability are excellent.

[0032] The minor diameter of the primary particles in the above Y180 is, for example, 30 to 100 nm, preferably 30 to 80 nm, and more preferably 30 to 50 nm. If the minor diameter of the primary particles is within this range, the particle size of the pigment in the dispersion / ink can be reduced, resulting in excellent printing density (OD) when used as an aqueous pigment dispersion or ink for IJ ink.

[0033] In addition, regarding the long diameter of the primary particles in the above-mentioned Y180, it is preferred that the aspect ratio and the short diameter are in the above-mentioned range, and the long diameter is, for example, 30 to 150 nm, preferably 30 to 100 nm, and more preferably 30 to 80 nm. The short diameter and long diameter of the primary particles and the aspect ratio calculated from them can be obtained by observing the primary particles of the pigment with an electron microscope, for example, from the average value of 100 measured lengths.

[0034] Y180 in the present invention can be a conventional synthetic product obtained by coupling a bis-nitrogen salt solution obtained by adding 1,2-bis(2-aminophenoxy)-ethane to an aqueous sodium nitrite solution in an ice-cold state in the presence of a strong acid to carry out a diazotization reaction with 5-acetoacetylamino-benzimidazolone, or a commercially available product such as "SYMULER FAST YELLOW BY2000 GT" (manufactured by DIC Corporation), and is preferably manufactured by further performing a unique treatment.

[0035] The above-mentioned unique treatment refers to, for example, using 200 to 1000 parts by mass of an inorganic salt relative to 100 parts by mass of a pigment (crude pigment), and grinding while heating in the presence of a solvent (solvent salt grinding). By grinding while heating in the presence of a solvent, the primary particle size can be set to a specific range while increasing the crystallinity of the pigment.

[0036] As the above-mentioned inorganic salt, water-soluble inorganic salts can be preferably used, for example, inorganic salts such as sodium chloride, potassium chloride, sodium sulfate, etc. are preferably used. In addition, inorganic salts with an average particle size of 0.5 to 50 μm are more preferably used. Such inorganic salts can be easily obtained by finely grinding ordinary inorganic salts. The amount of the inorganic salt used is, for example, 200 to 1000 parts by mass, preferably 300 to 800 parts by mass, relative to 100 parts by mass of the pigment. From the viewpoint of refining the pigment particles, it is preferred to have more inorganic salts, but in the present invention, from the viewpoint of achieving a balance with the crystallinity, the above range is preferred.

[0037] As the above-mentioned solvent, it is preferred to use an organic solvent that can inhibit crystal growth. As such an organic solvent, it is preferred to use a water-soluble organic solvent, for example, diethylene glycol (DEG), glycerine, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2-(methoxymethoxy) ethanol, 2-butoxyethanol, 2-(isopentyloxy) ethanol, 2-(hexyloxy) ethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, etc. can be used. Wherein, owing to being able to be set to appropriate heating temperature, the wettability with the pigment is also excellent, so diethylene glycol (DEG) is particularly preferred. From the viewpoint of forming appropriate viscosity when grinding, the usage amount of the solvent is, for example, 10 to 500 parts by mass relative to 100 parts by mass of the pigment, preferably 50 to 300 parts by mass.

[0038] The above-mentioned grinding (solvent salt grinding) is carried out by putting the pigment, the inorganic salt and the solvent that does not dissolve them into a mixing machine and mixing them therein. As the mixing machine at this time, for example, a kneader, a three-arm planetary mixer (Trimix), a mixing mill (mix muller) and the like can be used. The heating temperature during the grinding (solvent salt grinding) is, for example, 50 to 100° C., preferably 60 to 90° C. The heating temperature can be appropriately changed using the temperature regulating device possessed by the mixing machine. In addition, the time for grinding (solvent salt grinding) is, for example, 2 to 10 hours, preferably 3 to 8 hours.

[0039] The pigment composition of the present invention may also contain yellow pigments and dyes other than Y180. Examples of such yellow pigments include azo, disazo, azomethine, anthraquinone, quinophthalone, benzimidazolone, isoindoline, quinacridone, and perinone pigments. Specifically, CI 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, 213, etc. In addition, dyes and pigments other than the above-mentioned yellow pigments may also be contained. In the pigment composition of the present invention, Y180 is preferably 50% by mass or more in all pigments, and more preferably 60% by mass or more.

[0040] The content of the pigment in the pigment composition (the total content when two or more kinds are contained) is, for example, 50 to 99 mass %, preferably 60 to 98 mass %, and more preferably 70 to 98 mass %.

[0041] As the resin (dispersing resin) for improving the above-mentioned dispersibility, copolymer resins such as styrene-(meth) acrylic acid copolymers, styrene-maleic acid copolymers, diisobutylene-maleic acid copolymers, vinylnaphthalene-(meth) acrylic acid polymers, polyurethane resins, surfactants, etc. can be used. The content of these dispersing resins is, for example, 3 to 30 parts by weight, preferably 5 to 20 parts by weight relative to 100 parts by weight of the pigment such as Y180.

[0042] (derivative)

[0043] The zeta potential of the derivative is -20 mV or more and less than 0 mV, preferably -18 mV or more and less than 0 mV, and more preferably -16 mV or more and less than 0 mV. When the zeta potential is in this range, it can be easily adsorbed to the Y180 pigment, and as a result, the dispersion stability in the pigment composition can be improved. The zeta potential can be measured by electrophoretic light scattering measurement (laser Doppler method) using a zeta potential / particle size / molecular weight measurement system (product name ELSZ-2000ZS; manufactured by Otsuka Electronics Co., Ltd.) or the like.

[0044] In addition, the solubility parameter (SP) of the derivative is 21 or less, preferably 20 or less. When the solubility parameter (SP) is within this range, the affinity with the Y180 pigment is high, and as a result, the viscosity increase of the pigment composition over time can be suppressed, and the storage stability can be improved. The solubility parameter (SP) can be obtained from the SP value of the mixed solution when the derivative is mixed in an acetone solvent or the like having a known solubility parameter and the pigment is completely wetted.

[0045] Examples of the derivatives include derivatives having a pigment structure such as CI 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, 180, 185, and 213. Among them, derivatives of CI Pigment Yellow 180 (Y180) are preferred from the viewpoint of excellent dispersion stability and storage stability when used as a pigment composition. Y180 in the above derivatives refers to the yellow pigment (CAS No. 77804-81-0) represented by the chemical formula described in the above pigments.

[0046] The above derivatives may have acid groups such as carboxylic acid groups, hydroxyl groups, and sulfonic acid groups, and preferably have sulfonic acid groups. Sulfonic acid groups are composed of -SO 3 H, or a group consisting of an organic compound having a sulfonic group substituted on the carbon skeleton (-RSO 3 H; R is a carbon skeleton of an alkyl group or an aryl group). In the present invention, the sulfonic acid group is preferably -SO 3 The number of sulfonic acid groups (average number of substituents) possessed by the above derivative is, for example, 1 to 4, preferably 1 to 3, and more preferably 1 to 2. When the number of sulfonic acid groups (average number of substituents) is within the above range, the dispersion stability and storage stability of Y180 are improved.

[0047] The above-mentioned derivative may contain both or only one of a compound having one sulfonic acid group introduced into the same molecule (single-substituted product) and a compound having two sulfonic acid groups introduced into the same molecule (double-substituted product).

[0048] The molar ratio of the monosubstituted product to the disubstituted product (SN ratio (disubstituted product / monosubstituted product)) in the above derivative is, for example, 0.1 or more, preferably 0.1 to 30.0, and more preferably 0.5 to 5.0. When the SN ratio of the sulfonic acid group is within the above range, the dispersion stability and storage stability of Y180 are improved.

[0049] The average number of substituents in the sulfonic acid group of the above-mentioned derivatives and the SN ratio can be calculated from the area ratio of each compound in liquid chromatography.

[0050] In order to introduce sulfonic acid groups into derivatives such as Y180, for example, a sulfonating agent such as fuming sulfuric acid, concentrated sulfuric acid, or chlorosulfonic acid may be allowed to act on the derivative. The number of sulfonic acid groups can be adjusted by controlling reaction conditions such as sulfuric acid concentration, pigment component amount, reaction temperature, and reaction time. The pigment component amount here represents the weight ratio of Y180 to sulfuric acid (amount of pigment input / amount of sulfuric acid input).

[0051] The concentration of sulfuric acid is, for example, 92 to 100% by weight, preferably 92 to 98% by weight, and more preferably 95 to 98% by weight.

[0052] The amount of the pigment component is, for example, 0.04 to 0.08, preferably 0.04 to 0.07, and more preferably 0.05 to 0.07.

[0053] The reaction temperature is, for example, 5 to 30°C, preferably 5 to 20°C, and more preferably 10 to 20°C.

[0054] The reaction time is, for example, 0.5 to 5 hours, preferably 0.5 to 4 hours, and more preferably 1 to 4 hours.

[0055] The above-mentioned derivative is preferably a trivalent metal salt. As the trivalent metal in the trivalent metal salt, for example, there are iron, chromium, cobalt, aluminum, gallium, indium, and thallium, wherein, from the aspect of being able to make the zeta potential within an appropriate range and from the aspect of practicality, it is preferably selected from at least one of the group consisting of iron, chromium, cobalt and aluminum. The trivalent metal salt is a compound in which the hydrogen atom (H) of the above-mentioned sulfonic acid group is replaced with these metal ions. From the viewpoint of economy and performance, aluminum is preferred.

[0056] The above-mentioned derivatives can use pigment derivatives (synergists) other than the above-mentioned ones as needed. As such derivatives, pigment derivatives with a pigment as a skeleton and a substituent added to the pigment skeleton can be cited. Specifically, azo pigment derivatives, disazo pigment derivatives, azomethine pigment derivatives, anthraquinone pigment derivatives, quinophthalone pigment derivatives, benzimidazolone pigment derivatives, isoindoline pigment derivatives, quinacridone pigment derivatives, and purple cyclic ketone pigment derivatives can be used. As a derivative part, there are hydroxyl, carboxylic acid, sulfonic acid, etc. These derivatives can also be used in combination with two or more different types of derivatives.

[0057] The content of the above derivatives (the total content when two or more are included) is, for example, 0.5 to 30 parts by weight, preferably 1.0 to 20 parts by weight, and more preferably 2.0 to 15 parts by weight relative to 100 parts by weight of the pigment such as Y180. In addition, the content of the derivatives in the pigment composition (the total content when two or more are included) is, for example, 0.5 to 30% by weight, preferably 1.0 to 20% by weight, and more preferably 2.0 to 15% by weight. When the content of the derivatives is within this range, the adsorption effect of the derivatives to the pigment can be within an appropriate range, and as a result, the dispersion stability and storage stability in the pigment composition can be improved.

[0058] (IJ ink water-based pigment dispersion)

[0059] The aqueous pigment dispersion of the IJ ink of the present invention is not particularly limited as long as it contains the pigment composition of the present invention and a solvent for dispersing the pigment composition, and may contain other components such as a dispersant as necessary.

[0060] The aqueous pigment dispersion of IJ ink can use a water-soluble organic solvent together with water as a solvent. As such a water-soluble organic solvent, for example, alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, 1,2-hexanediol, 1,6-hexanediol, ketones such as acetone, methyl ethyl ketone, polyalkylene glycols such as ethylene glycol, diethylene glycol, propylene glycol, alkyl ethers of polyalkylene glycol, lactams such as N-methyl-2-pyrrolidone, etc. can be cited. These organic solvents can be used alone or in combination of two or more.

[0061] The content of the water-soluble organic solvent in the total mass of the aqueous pigment dispersion for IJ ink is, for example, about 0 to 60%, preferably 0 to 45%, and the remainder other than the pigment dispersion for IJ ink (non-volatile component) is mostly water.

[0062] [IJ water-based pigment ink]

[0063] The water-based pigment ink of the present invention is not particularly limited as long as it contains the pigment composition of the present invention, a solvent, etc., and may contain yellow pigments and dyes other than Y180. Examples of such yellow pigments include azo, disazo, azomethine, anthraquinone, quinophthalone, benzimidazolone, isoindoline, quinacridone, and perinone pigments. Specifically, CI 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, 213, etc. In addition, dyes and pigments other than the above-mentioned yellow pigments may also be contained. In addition, when mixing yellow pigments and dyes other than Y180, there is no particular restriction on the mixing method. It can be mixed as a pigment composition at the stage of manufacturing an aqueous pigment dispersion, or it can be mixed as a pigment dispersion at the stage of manufacturing an IJ aqueous pigment ink. In the aqueous pigment ink of the IJ ink of the present invention, Y180 is preferably 10% by mass or more in all pigments, and more preferably 20% by mass or more.

[0064] Water-based pigment ink can contain additives as needed. As additives, for example, preservatives, pH regulators, chelating agents, rust inhibitors, water-soluble ultraviolet absorbers, water-soluble polymer compounds, antioxidants, water-dispersible resins, surfactants can be cited. As surfactants, anionic, cationic, nonionic, amphoteric, silicone-based, and fluorine-based surfactants can be cited. In addition, water-based pigment ink can further add water, water-soluble organic solvents to adjust the ink concentration.

[0065] The content of additives in the total mass of the aqueous pigment ink (the total amount when two or more additives are contained) is about 0 to 30%, preferably 0 to 15%. The content of pigment in the aqueous pigment ink is, for example, 1 to 15% by mass, preferably 2 to 10% by mass.

[0066] From the viewpoint of improving the storage stability of the ink, the viscosity (25°C) of the aqueous pigment ink used is preferably 1 to 30 mPa·s, and more preferably 2 to 20 mPa·s. From the viewpoint of further improving the storage stability of the ink, the pH of the aqueous pigment ink is, for example, 7.0 or more, and preferably 7.5 or more. In addition, from the viewpoint of component resistance and skin irritation, the pH is, for example, 11.0 or less, and preferably 10.0 or less.

[0067] The aqueous pigment ink for IJ of the present invention can be loaded into a known IJ recording device and ejected onto a recording medium in the form of ink droplets to record images, etc. As IJ recording devices, there are continuous jet type (charge control type, spray type, etc.), on-demand type (piezoelectric method, thermal method, electrostatic attraction method, etc.), etc., and the aqueous pigment ink of the present invention can be used in any method.

[0068] Example

[0069] Hereinafter, the present invention will be described in more detail using examples and comparative examples. Derivatives were synthesized by the methods described in the following Preparation Examples 1 to 15, and pigments were synthesized by the methods described in Preparation Examples 1 and 2. Using these derivatives and pigments, pigment compositions were prepared by the methods described in the following Examples 1 to 9 and Comparative Examples 1 to 10. Furthermore, water-based IJ inks for evaluation were prepared from these pigment compositions, and these inks were evaluated. The evaluation results are described in the following Tables 3 and 4. It should be noted that in the present examples, "parts" and "%" represent "parts by weight" and "% by weight" unless otherwise specified.

[0070] (Preparation Example 1) [Synthesis of PY180 SA-1]

[0071] 50 parts of CI Pigment Yellow 180 (manufactured by DIC Corporation) were added to 750 parts of 95% sulfuric acid (manufactured by Kanto Chemical Co., Ltd.) (pigment content 0.067) at a temperature below 10°C. After heating to 15°C and stirring for 2 hours, the mixture was put into 1000 g of ice water to precipitate. The mixture was stirred for 30 minutes, filtered, and washed with 5% saline to obtain a wet cake of CI Pigment Yellow 180 sulfonic acid (PY180 SA-1). The wet cake was dried at 90°C, and the obtained solid was crushed with a juicer mixer to obtain PY180 SA-1.

[0072] (Preparation Example 2) [Synthesis of PY180 SA-2]

[0073] In the method of synthesis in the above-mentioned Preparation Example 1, a wet cake was obtained in the same manner except that CI Pigment Yellow 180 was changed to 45 parts and the reaction time was changed to 1 hour.

[0074] (Preparation Example 3) [Synthesis of PY180 SA-3]

[0075] In the method of the synthesis in the above Preparation Example 1, a wet cake was obtained in the same manner except that the sulfuric acid concentration was changed to 98%, CI Pigment Yellow 180 was changed to 40 parts, the reaction temperature was changed to 10° C., and the reaction time was changed to 1 hour.

[0076] (Preparation Example 4) [Synthesis of PY180 SA-4]

[0077] In the method of the synthesis in the above Preparation Example 1, a wet cake was obtained in the same manner except that the sulfuric acid concentration was changed to 98%, CI Pigment Yellow 180 was changed to 45 parts, the reaction temperature was changed to 10°C, and the reaction time was changed to 2.5 hours.

[0078] (Preparation Example 5) [Synthesis of PY180 SA-5]

[0079] In the method of the synthesis in the above Preparation Example 1, a wet cake was obtained in the same manner except that the sulfuric acid concentration was changed to 98%, CI Pigment Yellow 180 was changed to 45 parts, the reaction temperature was changed to 20° C., and the reaction time was changed to 1 hour.

[0080] (Preparation Example 6) [Synthesis of PY180 SA-6]

[0081] In the method of the synthesis in the above-mentioned Preparation Example 1, a wet cake was obtained in the same manner except that the sulfuric acid concentration was changed to 98% and the reaction time was changed to 4 hours.

[0082] (Preparation Example 7) [Synthesis of PY180 SA-Al-1]

[0083] 41 parts of the wet cake of PY180 SA-1 prepared in the above-mentioned Preparation Example 1 (solid content 23.4%) were added to 1000 parts of water and heated to 80°C while stirring. After the lumps of the wet cake disappeared, the pH was adjusted to 12.0-12.5 with a 25% sodium hydroxide aqueous solution, and the mixture was stirred for 30 minutes. 36 parts of aluminum sulfate 14-18 hydrate (manufactured by Kanto Chemical Co., Ltd.) were further added and stirred for 60 minutes. The mixture was filtered and washed with water to obtain a wet cake of aluminum salt of CI Pigment Yellow 180 sulfonic acid (PY180 SA-Al-1). The wet cake was dried at 90°C, and the obtained solid was crushed with a juicer mixer to obtain PY180 SA-Al.

[0084] (Preparation Example 8) [Synthesis of PY180-SA-Al-2]

[0085] In the method of synthesizing in the above-mentioned Preparation Example 7, a powder was obtained in the same manner except that the wet cake used was changed to PY180 SA-2.

[0086] (Preparation Example 9) [Synthesis of PY180-SA-Al-3]

[0087] In the method of synthesizing in the above-mentioned Preparation Example 7, a powder was obtained in the same manner except that the wet cake used was changed to PY180 SA-3.

[0088] (Preparation Example 10) [Synthesis of PY180-SA-Al-4]

[0089] In the method of synthesizing in the above-mentioned Preparation Example 7, a powder was obtained in the same manner except that the wet cake used was changed to PY180 SA-4.

[0090] (Preparation Example 11) [Synthesis of PY180-SA-Al-5]

[0091] In the method of synthesizing in the above-mentioned Preparation Example 7, a powder was obtained in the same manner except that the wet cake used was changed to PY180 SA-5.

[0092] (Preparation Example 12) [Synthesis of PY180-SA-Al-6]

[0093] In the method of synthesizing in the above-mentioned Preparation Example 7, a powder was obtained in the same manner except that the wet cake used was changed to PY180 SA-6.

[0094] (Preparation Example 13) [Synthesis of PY180 SA-TA]

[0095] 10 parts of PY180 SA prepared in the above Preparation Example 1 were added to 200 parts of a 1% sodium hydroxide aqueous solution and stirred for 30 minutes. 15 parts of triethanolamine (manufactured by Kanto Chemical Co., Ltd.) were added and stirred for 60 minutes. The mixture was filtered and washed with water to obtain a wet cake of the triethanolamine salt of CI Pigment Yellow 180 sulfonic acid (PY180 SA-TA). The wet cake was dried at 90°C and the obtained solid was crushed with a juicer mixer to obtain PY180SA-TA.

[0096] (Preparation Example 14) [Synthesis of PY180 SA analogues]

[0097] After dispersing 12 parts of 1,2-bis(2-aminophenoxy)-ethane in 72 parts of water, add 28.9 parts of 35% hydrochloric acid, add ice and keep it below 5°C, and drip 18.1 parts of 40% sodium nitrite aqueous solution to make a diazo component. Dissolve 11.6 parts of potassium 4-(acetoacetylamino)benzenesulfonate in 150 parts of water, and drip the total amount of the dissolved liquid into the diazo component at a constant speed. Then, disperse 13.7 parts of 5-acetoacetylamino-benzimidazolone in 218 parts of water, add 17.7 parts of 25% sodium hydroxide aqueous solution to dissolve it, and obtain a coupler component. For the coupler component, add water and ice to adjust the liquid volume to 500 parts. After adding 1.6 parts of 90% acetic acid to 660 parts of water, adjust the temperature of the solution to 20°C. After dripping the coupling agent component and adjusting the pH to 6.0, start dripping the diazo component at a constant speed. In order to prevent the presence of excess diazonium salt in the acetic acid solution, the coupling agent component is added dropwise while the diazo solution is added dropwise. The coupling is performed while the pH value of the acetic acid solution is adjusted to 6.0 by adjusting the dropping speed of the coupling agent component. Ice or 5% sodium hydroxide solution is added as appropriate during the coupling so that the temperature is maintained at 20°C and the pH is maintained at 6.0. After the coupling is completed in about 3 hours, it is heated to 90°C and maintained for 1 hour. Then, it is filtered, washed with water, and the obtained wet cake is dried at 90°C. The obtained solid is crushed with a juicer mixer to obtain a PY180 SA analog.

[0098] (Preparation Example 15) [Synthesis of PY180 SA-Al analogue]

[0099] 41.8 parts of wet cake of PY180 SA analog (solid content 23.9%) were added to 158.2 parts of water and heated to 80°C while stirring. Next, the pH was adjusted to 12.0-12.5 with a 25% sodium hydroxide aqueous solution, and the mixture was stirred for 30 minutes. 36 parts of aluminum sulfate 14-18 hydrate (manufactured by Kanto Chemical Co., Ltd.) were further added and stirred for 60 minutes. The mixture was filtered and washed with water to obtain a wet cake of PY180 SA-Al analog. The wet cake was dried at 90°C, and the obtained solid was crushed with a juicer mixer to obtain a PY180 SA-Al analog.

[0100] (Manufacturing Example 1 [Synthesis of Pigment (Y180)]

[0101] After dispersing 225 parts of 1,2-bis(2-aminophenoxy)-ethane in 3300 parts of water, 538.5 parts of 35% hydrochloric acid were added, and 337 parts of 40% sodium nitrite aqueous solution were added dropwise while adding ice to keep the temperature below 5°C to prepare a diazo component. Next, 455 parts of 5-acetoacetylamino-benzimidazolone were dispersed in 3400 parts of water, and 595 parts of 25% sodium hydroxide aqueous solution were added to dissolve the mixture to obtain a coupling agent component. Regarding the diazo component and the coupling agent component, water and ice were added to adjust the liquid amounts to 6500 parts and 4500 parts, respectively. After adding 30.6 parts of 90% acetic acid to 6500 parts of water, the temperature of the solution was adjusted to 20°C. After the coupling agent component was added dropwise to adjust the pH to 6.0, the diazo component was started to be added dropwise at a constant rate. In order to prevent the presence of excess diazonium salt in the acetic acid solution, the coupling agent component is added dropwise while the diazo solution is added dropwise. The coupling is performed while the pH value of the acetic acid solution is adjusted to 6.0 by adjusting the dropping speed of the coupling agent component. Ice or 5% sodium hydroxide solution is added in a timely manner to maintain the temperature at 20°C and the pH at 6.0 during the coupling. After the coupling is completed in about 3 hours, it is heated to 90°C and maintained for 1 hour. Then, it is filtered, washed with water, and the obtained wet cake is dried at 90°C. The obtained solid is crushed with a juicer mixer to obtain Y180 pigment.

[0102] (Manufacturing Example 2 [Grinding of Pigment (Y180)]

[0103] 500 parts of the yellow powder of the Y180 pigment obtained in Preparation Example 1, 2500 parts of salt, and 500 parts of diethylene glycol were placed in a 15L three-arm planetary mixer (TM; manufactured by Inoue Seisakusho Co., Ltd.), and the temperature was set so that the internal temperature was maintained at 80°C to 100°C, and then ground for 5 hours. The ground pigment composition was placed in warm water at 50°C, stirred, and after being fully re-slurried, filtered and washed with water, and the obtained wet cake was dried at 90°C. The obtained solid was crushed with a juicer mixer to obtain a powder.

[0104] [Measurement of Zeta Potential]

[0105] The zeta potential of the derivative was measured by the following method. The obtained evaluation results are shown in Table 1.

[0106] Zeta potential is measured using a Zeta potential / particle size / molecular weight measurement system (product name "ELSZ-2000Z", manufactured by Otsuka Electronics Co., Ltd.). First, 5 mg of the measurement sample and 5 mL of pure water are measured in a 30 mL sample bottle, and dispersed for 15 minutes using an ultrasonic cleaner (product name "Bransonic M2800-J", manufactured by Yamato Science Co., Ltd.). Next, 100 μL of the dispersion of the measurement sample and 10 mL of pure water are measured in a 30 mL sample bottle, and dispersed for 1 minute using Bransonic M2800-J. The prepared measurement solution is injected into the flow cell unit, and the cell is set in the ELSZ-2000Z to confirm the scattering intensity. If the scattering intensity is within the appropriate range for measurement (10,000 to 50,000 cps), the measurement is continued. If it deviates from the appropriate range, the concentration of the measurement sample is adjusted to be within the appropriate range, and then the measurement is performed. The measurement conditions using ELSZ-2000Z were as follows, and the measurement was repeated three times, and the average value was used as the zeta potential in water of the measurement sample.

[0107] [Measurement conditions]

[0108] Measurement temperature: 25℃

[0109] Determination waiting time: 300 seconds

[0110] Pinhole: 50

[0111] Total times: 10 times

[0112] Pool measurement position: 0.70 / 0.35 / 0.00 / -0.35 / -0.70

[0113] Applied voltage: Fixed

[0114] Applied voltage (fixed): 60

[0115] Applied voltage waveform type: Auto

[0116] Constant current: 51mA

[0117] Lorentz fit: unimodal

[0118] Zeta potential conversion formula: Smoluchows

[0119] [Table 1]

[0120] derivative Zeta potential (mV) PY180SA-1 -38.7 PY180SA-AI-1 -12.5 PY180SA-AI-2 -17.0 PY180SA-AI-3 -12.2 PY180SA-AI-4 -14.7 PY180SA-AI-5 -13.8 PY180SA-AI-6 -14.3 PY180SA-TA -25.9 PY180SA analogs -42.7 PY180SA-AI analogs -19.8

[0121] [Determination of solubility parameters]

[0122] The solubility parameters of the pigments and derivatives were measured by the following method. The obtained evaluation results are shown in Table 2.

[0123] Add 50 ml of pure water and X ml of acetone to a 100 ml beaker and stir slowly with a stirrer. Add 0.1 g of the pigment or derivative as the test sample, and set the amount of acetone when the pigment or derivative is completely precipitated after stirring for 1 minute as X. Calculate the solubility parameter (δm) according to the following formula.

[0124] δm=(50×δw+X×δa) / (50+X)

[0125] δw=23.43

[0126] δa=9.75

[0127] [Table 2]

[0128] derivative Solubility parameter (δm) PY180SA-1 23.3 PY180SA-AI-1 19.8 PY180SA-AI-2 20.6 PY180SA-AI-3 19.8 PY180SA-AI-4 19.9 PY180SA-AI-5 20.0 PY180SA-AI-6 20.2 PY180SA-TA 21.5 PY180SA analogs 22.4 PY180SA-AI analogs 20.8

[0129] (Examples 1-9 and Comparative Examples 1-10)

[0130] 20 parts of the pigment obtained in Preparation Example 2 and 10.6 parts of PY180 SA-A1 were placed in a mixer (product name "LAB MILL", manufactured by Osaka Chemical Co., Ltd.), and blended for 10 seconds, which was repeated 3 times to obtain a pigment composition. For Examples 2 to 9 and Comparative Examples 1 to 10, pigment compositions were obtained in the same manner as in Example 1 using the pigments and derivatives shown in Tables 3 and 4 below. In addition, for Comparative Examples 1, 5, 7, and 9, each pigment was used directly without being treated with a mixer.

[0131] [Evaluation of the preparation of water-based IJ ink]

[0132] For the pigment composition 4.0g obtained above, add styrene-(methyl) acrylic copolymer (acid value: 167, active ingredient 45 mass %) 1.8g, 25 mass % potassium hydroxide aqueous solution 0.4g, isopropyl alcohol 1.0g and ion exchange water 22.8g as dispersion resin, make the total amount of water-based pigment dispersion liquid 30.0g. Then, in water-based pigment dispersion liquid, add 1mm glass beads, use coating regulator to disperse 90 minutes. Thereafter, add ion exchange water and prepare dispersion liquid in the mode that non-volatile component becomes 15 mass %. In this water-based pigment dispersion liquid 9.6g, add trade name: Surfynol465 (Nissin Chemical Industry Co., Ltd. system) 0.2g, glycerine 2.3g, triethylene glycol 1.7g, 2-pyrrolidone 1.4g, 1,2-hexanediol 0.8g, ion exchange water 14.0g, make the total amount 30.0g, make water-based IJ ink.

[0133] The initial viscosity, change rate, and viscosity determination results of the obtained aqueous IJ inks for evaluation are shown in Table 3, and the initial particle size, change rate, and particle size determination results are shown in Table 4. The pigments shown in Tables 3 and 4 below are as follows.

[0134] ·pigment

[0135] PY180-A...Pigment obtained in Production Example 1

[0136] PY180-B...Pigment obtained in Production Example 2

[0137] PY180-C…Trade name: TONER YELLOW HG (manufactured by Clariant Japan Co., Ltd.)

[0138] PY180-D…Trade name: PV FAST YELLOW HG01 (manufactured by Clariant Japan Co., Ltd.)

[0139] [Table 3]

[0140]

[0141] [Table 4]

[0142]

[0143] [SN ratio measurement]

[0144] The SN ratio of the derivative is calculated using a liquid chromatograph (product name "Agilent 1100", manufactured by Agilent Technologies Co., Ltd.). First, 5 mg of the test sample and 10 mL of dimethyl sulfoxide (manufactured by Kanto Chemical Co., Ltd.) are measured in a 30 mL sample bottle and mixed for 10 seconds using an oscillator (product name "VORTEX-GENIE2", manufactured by Scientific Industries). Next, the mixture is mixed at 130 rpm for 1 hour while maintaining 25°C using a constant temperature oscillator (product name "PERSONAL-11", manufactured by TAITEC Co., Ltd.). Then, the test sample is filtered with a 0.45 μm filter (manufactured by ADVANTECH) and aliquoted into a 2 ml sample bottle, which is set in Agilent 1100 for measurement. The peak detected at a retention time of 11.4 to 12.4 is a 2-substituted product, and the peak detected at a retention time of 14.7 to 14.9 is a 1-substituted product. The SN ratio was calculated from these HPLC area values ​​according to the following formula: The HPLC measurement conditions were as follows, and the measurement was repeated twice, and the average value was used as the SN ratio of the measurement sample.

[0145] [Calculation formula]

[0146] SN ratio = area value of 2-substituted product / area value of 1-substituted product

[0147] [HPLC measurement conditions]

[0148] Column: C18 U120 S3 (Φ4.6mm×100mm, 3μm)

[0149] Eluent 1: 30 mM ammonium acetate

[0150] Eluent 2: Methanol

[0151] Gradient (1 / 2): 90 / 10 (~3 minutes)

[0152] 0 / 100(~40 minutes)

[0153] 90 / 10 (~50 minutes)

[0154] Flow rate: 1.0mL / min

[0155] Oven: 50℃

[0156] Wavelength: 400nm

[0157] Injection volume: 1.0 μL

[0158] [Viscosity measurement]

[0159] The initial viscosity in the above Table 3 was measured by the following method.

[0160] The viscosity was measured using an E-type viscometer TV-25 (manufactured by Toki Sangyo Co., Ltd.) at 20°C and 30 rpm. The dispersion was allowed to stand in a thermostatic chamber at 70°C for 1 week, and the viscosity was measured in the same manner. The storage stability was determined from the change in viscosity before heating (viscosity ratio).

[0161] (Judgment Criteria)

[0162] ◎: Change rate is less than 120%

[0163] ○: Change rate is 120% or more and less than 140%

[0164] △: Change rate 140% or more and less than 200%

[0165] ×: Change rate is 200% or more

[0166] [Dispersed average particle size]

[0167] The primary particle sizes in Table 4 above were measured by the following method.

[0168] The average dispersed particle size Mv was calculated by measuring with a particle size distribution measuring apparatus (product name "Nanotrac Wave II", manufactured by Microtrac BEL Co., Ltd.). The dispersion was left to stand in a thermostatic chamber at 70°C for 1 week, and Mv was calculated in the same manner. The storage stability was determined by the change in Mv before heating (Mv ratio).

[0169] (Judgment Criteria)

[0170] ◎: Initial particle size is less than 200nm and the change rate is less than 150%

[0171] ○: Initial particle size is less than 200 nm and the change rate is more than 150% and less than 200%

[0172] △: Initial particle size is less than 200 nm and the change rate is more than 200% and less than 250%

[0173] ×: Initial particle size 200 nm or more or change rate 250% or more

[0174] According to Table 3, the pigment composition of the present invention (Example 1-9) using a derivative having a zeta potential of -20 mV or more and less than 0 mV and a solubility parameter of 21 or less for Y180 pigment has a smaller rate of change in viscosity than Comparative Examples 1-10. In addition, according to Table 4, the pigment composition of the present invention (Example 1-9) has a smaller rate of change in particle size than Comparative Examples 1-10. It can be seen from this that the pigment composition of the present invention is excellent in dispersion stability and storage stability when made into an aqueous IJ ink.

Claims

1. A pigment composition comprising CI Pigment Yellow 180 and a derivative having a zeta potential of -20 mV or more and less than 0 mV and a solubility parameter of 21 or less.

2. The pigment composition according to claim 1, in, The aspect ratio of the CI Pigment Yellow 180 is 1.0 to 2.

0.

3. The pigment composition according to claim 1 or 2, in, The derivative is a derivative of CI Pigment Yellow 180.

4. The pigment composition according to claim 1 or 2, in, The derivative has a sulfonic acid group.

5. The pigment composition according to claim 1 or 2, in, The derivative is a salt of a trivalent metal, and the trivalent metal is at least one selected from the group consisting of iron, chromium, cobalt, and aluminum. 6 . An aqueous pigment dispersion for inkjet ink, comprising the pigment composition according to claim 1 or 2.

7. An aqueous pigment ink for inkjet, comprising the pigment composition according to claim 1 or 2.

Images