Dispersant, dispersion, and ink composition, and methods of manufacturing these

Abstract

To provide a dispersant capable of dispersing disperse dyes and pigments with a small amount of additive and exhibiting wettability, a dispersion capable of exhibiting redispersibility, an ink composition utilizing these, and methods of manufacturing these.SOLUTION: The present invention provides a dispersant, a dispersion, and an ink composition, each characterized by containing (A) a styrene-ethyleneoxy group-containing (meth)acrylic acid-based copolymer having a weight average molecular weight of 1,000 to 50,000, which comprises (a1) a styrene-containing copolymer having a styrene content of 1 to 40 mass%, and further characterized in that the surfactant content is less than 0.1 mass%. The present invention also provides methods of manufacturing the same.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a dispersant, a dispersion, and an ink composition used for dispersing disperse dyes and pigments, and methods for producing the same.

Background Art

[0002] Conventionally, disperse dyes and pigments have been used as colorants for inks. When using disperse dyes and pigments in inks, it is necessary to disperse the micronized disperse dyes and pigments in water. However, since disperse dyes and pigments are insoluble in water, it is important to keep the disperse dyes and pigments in a dispersed state and maintain stability for a long time.

[0003] Furthermore, inks containing water-insoluble colorants such as disperse dyes and pigments have the drawback that when the contained moisture is lost due to some factor and the ink becomes dry, the dispersed state of the pigment is broken and pigment aggregation occurs. Once aggregated, the disperse dyes and pigments in the ink cannot return to the dispersed state again even when a liquid medium such as water is added (poor redispersibility), so improvement is strongly demanded.

[0004] As dispersants for inks, nonionic surfactants, anionic surfactants, polymer surfactants, etc. have been proposed conventionally. For example, Patent Document 1 and Patent Document 2 disclose that a nonionic surfactant containing an acetylene group is useful as a pigment dispersant. However, although the nonionic surfactant containing an acetylene group is excellent in the penetrability and antifoaming property of the ink, its dispersing ability is inferior, such as requiring time for dispersion compared with other dispersants, and no redispersing effect can be expected.

[0005] As a method for facilitating the redispersion of pigments, for example, Patent Document 3 proposes a method of coating the particle surface of pigments with a silane coupling agent or a specific dispersant to suppress direct contact between pigments and strong aggregation and adhesion.

[0006] In addition, Patent Document 4 and Patent Document 5 disclose that a pigment dispersion using an acrylic polymer enhances the redispersibility of ink, but the process is complicated, such as the need to crosslink the polymer in the pigment aqueous dispersion or the need to perform living radical polymerization. Therefore, the development of a dispersant that can more easily achieve the redispersing effect is desired.

[0007] Furthermore, Patent Document 6 discloses a dispersion resin having a hydrophobic monomer, an acrylic monomer, and a hydrophilic vinyl monomer having a sulfonic acid group. However, since the proportion of the hydrophobic monomer is high, the dispersion effect may not be exhibited in aqueous ink in some cases.

[0008] Patent Document 7 discloses that an inkjet ink using a styrene-(meth)acrylic acid copolymer and a specific acetylene glycol compound has high-quality and stable recording performance, and can increase the printing density on the fabric surface while maintaining the storage stability of the ink. However, the redispersibility after drying is not explicitly stated.

[0009] In addition, as an invention of the present inventors, an application has been previously filed for an invention related to a dispersant using a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer and an acetylene-based surfactant (Japanese Patent Application No. 2022-155738). Although this dispersant can exhibit redispersibility, since its effect is exerted by the combination of two components, there is room for further improvement in the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a dispersant capable of dispersing disperse dyes and pigments even with a small addition amount, further capable of exhibiting wettability, a dispersion capable of exhibiting redispersibility, an ink composition using these, and methods for producing these. [Means for Solving the Problems]

[0012] As a result of intensive studies to achieve the above object, the present inventors have found that when a specific styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer is used as a dispersant, dispersibility and wettability can be exhibited with a small addition amount, excellent micronization of disperse dyes and pigments can be achieved, and further redispersibility can be exhibited, leading to the completion of the present invention.

[0013] Therefore, the present invention provides the following dispersant, dispersion, ink composition, and methods for producing these. 1. (A) A styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a weight average molecular weight of 1,000 to 50,000, containing a copolymer in which (a1) the content of styrene is 1 to 40% by mass, and the content of surfactant is less than 0.1% by mass. A dispersant characterized by the above. 2. The component (A) is as follows (a1) to (a3), (a1) Styrene: 1 to 40% by mass (a2) An ethyleneoxy group-containing (meth)acrylic acid alkyl ester monomer: 1 to 59% by mass (a3) Monomers other than (a1) to (a2): 1 to 98% by mass The dispersant according to claim 1, which is a polymer of . 3. The dispersant according to claim 2, wherein the monomer of the component (a3) includes a radically polymerizable monomer containing at least one functional group. 4. The dispersant according to claim 1 or 2, wherein the component (A) is a neutralized product with a basic compound having an octanol / water partition coefficient of -5.0 or more and 0 or less. 5. The dispersant according to claim 1 or 2, which does not contain an acetylene-based surfactant. 6. The dispersant according to claim 1 or 2, which is for aqueous solvent dispersion of a disperse dye or a pigment. 7. A dispersion comprising a dispersant, a disperse dye and / or a pigment, and an aqueous solvent, wherein the dispersant is the dispersant according to claim 1 or 2. 8. An ink composition comprising the dispersion according to claim 7. 9. A method for producing the dispersant according to claim 1 or 2, wherein the component (A) includes a neutralization step with a basic compound having an octanol / water partition coefficient of -5.0 or more and 0 or less. 10. A method for producing a dispersion, comprising a step of mixing and dispersing the dispersant according to claim 1 or 2, a disperse dye and / or a pigment, and an aqueous solvent. 11. The following steps (a) and (b) (a) A step of mixing and dispersing the dispersant according to claim 1 or 2, a disperse dye and / or a pigment, and an aqueous solvent to obtain a dispersion; (b) A step of mixing the dispersion with at least one substance selected from the group consisting of water, a water-soluble organic solvent, a resin, an ultraviolet absorber, an antioxidant, a pH adjuster, a preservative, and a viscosity adjuster A method for producing an ink composition, characterized by including the above steps.

Advantages of the Invention

[0014] According to the dispersant of the present invention, disperse dyes and pigments can be dispersed with a small addition amount regardless of the types of disperse dyes and pigments. Further, the dispersion and the ink composition using this dispersant exhibit wettability and dispersion stability, and can further exhibit redispersibility.

Embodiments for Carrying Out the Invention

[0015] The dispersant of the present invention contains (A) a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a weight average molecular weight of 1,000 to 50,000. Component (A) is preferably a neutralized product with a basic compound having an octanol / water partition coefficient of -5.0 or more and 0 or less.

[0016] The styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a weight average molecular weight of 1,000 to 50,000 of component (A) is (a1) Styrene: 1 to 40% by mass (a2) An ethyleneoxy group-containing (meth)acrylic acid alkyl ester monomer: 1 to 59% by mass (a3) Monomers other than (a1) to (a2): 1 to 98% by mass and is preferably a polymer thereof. Component (A) may be a random copolymer or a block copolymer.

[0017] The content of styrene as component (a1) is 1 to 40% by mass, preferably 10 to 30% by mass, based on 100% by mass of the monomers of components (a1) to (a3). By setting this content within the range of 1 to 40% by mass, the effect of redispersibility can be obtained in the dispersion.

[0018] The ethyleneoxy group-containing (meth)acrylic acid alkyl ester monomer as component (a2) preferably has an ethyleneoxy group addition mole number of 1 to 100 moles, more preferably 5 to 90 moles, and even more preferably 10 to 90 moles.

[0019] The weight average molecular weight of the ethyleneoxy group-containing (meth)acrylic acid alkyl ester monomer as component (a2) is preferably 100 to 5,000.

[0020] Specific examples of the component (a2) include acrylic acid alkyl ester monomers modified with polyethylene glycol. Specific examples include polyethylene glycol mono(meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, ethoxypolyethylene glycol mono(meth)acrylate, polyethylene glycol-modified 2-isocyanatoethyl (meth)acrylate, polyethylene glycol-propylene glycol mono(meth)acrylate, and the like. Particularly preferred is polyethylene glycol mono(meth)acrylate.

[0021] The above polyethylene glycol mono(meth)acrylate is represented by the following formula. [Chemical formula] (In the formula, R represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and p represents a positive number from 1 to 100.)

[0022] Commercially available products of the above component (a2) include, for example, Brenmer "PME-400", "PME-1000", "PME-4000", "PE-200", "PE-350", "AE-200", "AE-400", "AME-400" manufactured by NOF Corporation; Light Ester "130MA", "041MA", Light Acrylate "MTG-A", "130A" manufactured by Kyoeisha Chemical Co., Ltd.; Fancryl "FA-400M(100)" manufactured by Showa Denko Materials Co., Ltd.; NK Ester "AM-90G", "AM-130G", "AM-230G", "M-90G", "M-130G", "M-230G", "M-450G" manufactured by Shin-Nakamura Chemical Co., Ltd.; VISIOMER "MPEG 750MA W", "MPEG 1005 MA W", "MPEG 2005 MA W", "MPEG 5005 MA W" manufactured by Evonik Corporation, and the like.

[0023] The ethylene oxide group-containing (meth)acrylic acid alkyl ester monomer of the above component (a2) is 1 to 59% by mass, preferably 5 to 55% by mass, based on 100% by mass of the monomers (a1) to (a3). By setting the content of the component (a2) within the range of 1 to 59% by mass, when used as a dispersant, an effect of dispersibility can be obtained for disperse dyes and pigments.

[0024] The monomer other than (a1) to (a2) as the above component (a3) is not particularly limited. For example, it includes (meth)acrylic acid alkyl ester monomers and / or radical polymerizable monomers containing functional groups such as carboxy groups, amide groups, hydroxy groups, epoxy groups, and sulfonic acid groups. These can be used alone or in combination of two or more, but preferably contain at least one of the radical polymerizable monomers containing functional groups such as carboxy groups, amide groups, hydroxy groups, epoxy groups, and sulfonic acid groups. Particularly preferably, they are (meth)acrylic acid alkyl ester monomers and / or carboxy group-containing radical polymerizable monomers and hydroxy group-containing radical polymerizable monomers.

[0025] The (meth)acrylic acid alkyl ester monomer having a linear or branched structure, an alicyclic group, an aromatic ring group, etc. is not particularly limited, but does not include the ethylene oxide group-containing (meth)acrylic acid alkyl ester monomer as the above component (a2).

[0026] Examples of the (meth)acrylic acid alkyl ester monomer having a linear or branched structure include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, etc.

[0027] Examples of the (meth)acrylic acid ester monomer having an alicyclic group include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and the like.

[0028] Examples of the (meth)acrylic acid ester monomer having an aromatic ring group include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and the like.

[0029] Examples of the radical polymerizable monomer containing a carboxy group include methacrylic acid, acrylic acid, carboxyethyl (meth)acrylate, fumaric acid, itaconic acid, maleic acid, crotonic acid, vinylbenzoic acid, maleic acid monobutyl ester, itaconic acid monomethyl ester, itaconic acid butyl ester, and the like.

[0030] Examples of the radical polymerizable monomer containing an amide group include N-methoxymethylacrylamide, N-ethoxymethylacrylamide, N-butoxymethylacrylamide, and the like.

[0031] Examples of the radical polymerizable monomer containing a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1-methyl-4-hydroxybutyl (meth)acrylate, 1-methyl-4-hydroxypentyl (meth)acrylate, and the like.

[0032] Examples of the radical polymerizable monomer containing an epoxy group include glycidyl (meth)acrylate, methallyl glycidyl ether, and the like.

[0033] Examples of the sulfonic acid group-containing radically polymerizable monomer include sodium p-styrenesulfonate, lithium p-styrenesulfonate, N-t-butylacrylamidosulfonic acid, sodium 2-sulfoethyl methacrylate, polycyclic phenyl ether methacrylate sulfate ester salt, sodium N-sulfonic acid polyoxyalkylene methacrylate, ammonium polyoxyalkylene alkenyl ether sulfonate, and the like.

[0034] Examples of commercially available sulfonic acid group-containing radically polymerizable monomers include, for example, Spinnomer "NaSS" (sodium p-styrenesulfonate), "LiSS" (lithium p-styrenesulfonate) manufactured by Tosoh Finechem Corporation, "ATBS" (N-t-butylacrylamidosulfonic acid) manufactured by Toagosei Co., Ltd., Antox "MS-2N-D" (sodium 2-sulfoethyl methacrylate), "MS-60" (polycyclic phenyl ether methacrylate sulfate ester salt) manufactured by Nippon Emulsifier Co., Ltd., Eleminol "JS-20", "RS-3000" (sodium N-sulfonic acid polyoxyalkylene methacrylate) manufactured by Sanyo Chemical Industries, Ltd., Latemul "PD-104", "PD-105" (ammonium polyoxyalkylene alkenyl ether sulfonate) manufactured by Kao Corporation, and the like.

[0035] The content of the monomer other than the components (a1) to (a2) is 1 to 98% by mass, preferably 10 to 80% by mass, based on 100% by mass of the monomers (a1) to (a3). If this content is less than 1% by mass, there is a problem that it becomes difficult to solubilize the acrylic resin, and if it exceeds 98% by mass, the effect of imparting redispersibility to the dispersion may be impaired.

[0036] The monomers of the components (a1) to (a3) can be polymerized by known polymerization methods, such as solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. Among these known polymerization methods, solution polymerization is preferably applied because of the simplicity of equipment and operation.

[0037] In order to efficiently proceed the polymerization reaction, known polymerization initiators can be used. The polymerization initiator can be appropriately selected according to the polymerization method, polymerization conditions, and solubility in the solvent. However, from the viewpoints of safety and polymerization efficiency, it is preferable that the 10-hour half-life temperature is 70 to 110 °C. If the 10-hour half-life temperature is less than 70 °C, the stability at room temperature is low, so the risk of ignition may increase. If the 10-hour half-life temperature is 110 °C or higher, since the polymerization reaction requires high temperature and long time, the production efficiency may decrease. Specifically, azobis compounds such as 2,2'-azobis-isobutyronitrile, organic peroxides such as benzoyl peroxide, inorganic peroxides such as sodium persulfate, and redox catalyst systems composed of combinations of such oxidants and reducing agents such as bisulfites can be mentioned, and these can be used alone or in combination of two or more kinds.

[0038] A chain transfer agent can be added to adjust the molecular weight to a preferable range. Alcohols such as catechol, mercaptans such as n-dodecyl mercaptan, carbon halides such as carbon tetrachloride, etc. are exemplified, and these can be used alone or in combination of two or more kinds. Considering the chain transfer constant and safety, the selection of mercaptans is preferable, and high-boiling mercaptans such as n-dodecyl mercaptan are particularly preferable in that the odor of the remaining mercaptans can be suppressed.

[0039] It is preferable to use a solvent because the polymer can be handled in a solution state and can be synthesized with a simple apparatus. An appropriate solvent can be selected according to the polymerization method to be applied, polymerization conditions, solubility of raw materials, and solvent composition of the dispersion composition using a dispersant. When producing an aqueous dispersant, it is preferable to select one having a boiling point of 60 to 120 °C under standard conditions. If the boiling point is less than 60 °C, it may be difficult to efficiently proceed with the polymerization in a short time. On the other hand, if the boiling point is 120 °C or higher, a large amount of energy may be required for distillation under reduced pressure. Preferred solvents include water (boiling point 100 °C), alcohols such as 2-propanol (boiling point 82 °C), esters such as ethyl acetate (boiling point 77 °C), ketones such as 2-butanone (boiling point 80 °C), aromatic hydrocarbons such as toluene (boiling point 111 °C), and ethers such as tetrahydrofuran (boiling point 66 °C). These can be used alone or in combination of two or more. When producing an aqueous dispersant, water-miscible alcohols, ethers, and mixed solvents of these with other organic solvents and / or water are preferably used. Considering safety and economy, 2-propanol and mixed solvents of 2-propanol with other organic solvents and / or water are more preferably used.

[0040] The styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer obtained by polymerization is neutralized with a basic compound characterized in that the octanol / water partition coefficient is -5.0 or more and 0 or less. By neutralizing some or all of the functional groups of the polymer with a basic compound, the dissolution state or dispersion state of the polymer in the solvent is stabilized. The basic compound may be added in the monomer state and then polymerized, or may be added after polymerizing the monomer having an acidic functional group.

[0041] The water solubility and acidity of the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer, and the water solubility and basicity of the basic compound also depend thereon. The basic compound is preferably added so that the pH of a 20% aqueous solution of the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer is in the range of 7 to 13, more preferably added so that the pH of a 20% aqueous solution of the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer is in the range of more than 7 to 11, and particularly preferably added so that the pH of a 20% aqueous solution of the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer is in the range of 8 to 10. When the pH of the polymer aqueous solution is less than 7, the solubility of the polymer in water is insufficient, and the polymer may precipitate or deposit in water, which is not preferable. On the other hand, when the pH of the polymer aqueous solution is higher than 13, the polymer may deteriorate over time due to hydrolysis, which is not preferable.

[0042] The octanol / water partition coefficient (logPow) of the basic compound is in the range of -5.0 to 0, preferably -4.0 to 0. Here, the octanol / water partition coefficient (logPow) in the present invention is a value obtained in accordance with "Measurement of partition coefficient (1-octanol / water) - Flask immersion method" of JIS Z7260-107 (2000). The basic compound used in the present invention is a basic compound having high water solubility and hydrophilicity.

[0043] Furthermore, the basic compound can be appropriately selected in consideration of its compatibility with the dispersion system and the composition of the dispersion composition using the dispersant. By using a basic compound having a boiling point of 100 °C or higher, the basic compound remains in the dried product, and the redissolution property becomes high when water is added. Examples of such basic compounds include organic amine compounds such as 2-amino-2-methyl-1-propanol (partition coefficient = -0.74, boiling point 165 °C), morpholine (partition coefficient = -0.84, boiling point 129 °C), 1-amino-2-propanol (partition coefficient = -0.96, boiling point 159 °C), 3-amino-1-propanol (partition coefficient = -1.12, boiling point 187 °C), diethanolamine (partition coefficient = -1.43, boiling point 268 °C), monoethanolamine (partition coefficient = -1.31, boiling point 171 °C), triethanolamine (partition coefficient = -1.59, boiling point 335 °C), and alkali metal hydroxides such as sodium hydroxide (partition coefficient = -3.88, boiling point 1390 °C) and potassium hydroxide (partition coefficient = -3.88, boiling point 1320 °C).

[0044] The (A) styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer obtained by the above method has a weight average molecular weight (Mw) of 1,000 to 50,000, preferably 3,000 to 30,000. When this weight average molecular weight (Mw) is less than 1,000, the dispersion stabilizing power for disperse dyes and pigments decreases. When it is greater than 50,000, the ability to disperse disperse dyes and pigments decreases, and the viscosity of the ink may become too high, which is not preferable. The weight average molecular weight can be measured by the GPC (gel permeation chromatography) method.

[0045] (A) The acid value of the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer is preferably 50 to 300, more preferably in the range of 100 to 250. When the acid value is less than 50, the solubility of the resin in water deteriorates, and the dispersion stabilizing power for disperse dyes and pigments tends to be inferior. When the acid value exceeds 300, the affinity with the aqueous medium becomes strong, and bleeding tends to occur easily in the printed image, which is not preferable. The acid value of the resin represents the number of mg of KOH required to neutralize 1 g of the resin and is measured according to JIS-K 3054.

[0046] The dispersant of the present invention can be obtained by mixing the component (A) and other components such as an aqueous solvent as required, and is characterized in that the content of the surfactant in the dispersant is less than 0.1% by mass. In particular, it is preferably free of acetylene-based surfactants. Even without containing an acetylene-based surfactant, desired performance can be obtained.

[0047] The dispersion of the present invention contains the above-mentioned (A) styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a weight average molecular weight of 1,000 to 50,000, a disperse dye and / or a pigment, and an aqueous solvent.

[0048] The constituent components of the above dispersion will be described below. In the dispersion of the present invention, the blending amount of the dispersant is preferably 1 to 100 parts by mass, more preferably 3 to 80 parts by mass, and still more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the disperse dye and the pigment. If the blending amount of the dispersant is too small, the disperse dye and the pigment cannot be sufficiently dispersed. If the blending amount of the dispersant is too large, there will be many dispersants in the dispersion that are not adsorbed on the disperse dye and the pigment, which is not preferable.

[0049] Disperse dyes are not particularly limited, and known ones can be used. Disperse dyes are classified into chemical structures such as benzene azo-based (monoazo, disazo), heterocyclic azo-based (thiazole azo, benzothiazole azo, pyridone azo, pyrazolone azo, thiophene azo, etc.), anthraquinone-based, and condensed-based (quinophthalone, styryl, coumarin, etc.). Since they do not have water-soluble groups, they are poorly soluble in water and have characteristics such as a molecular weight of 2,000 or less and being smaller than other dyes.

[0050] Examples of disperse dyes that can be preferably used in the present invention are shown below. Yellow dyes such as C.I.Disperse Yellow 3, 4, 5, 7, 9, 13, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63, 64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100, 104, 114, 116, 118, 119, 122, 124, 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 186, 192, 198, 199, 202, 204, 210, 211, 215, 216, 218, 224; Orange dyes such as C.I.Disperse Orange 1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 47, 48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142; Red dyes such as C.I.Disperse Red 1, 4, 5, 7, 11, 12, 13, 15, 17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75, 76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108, 110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135, 137, 143, 145, 146, 151, 152, 153, 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 239, 240, 257, 258, 277, 278, 279, 281, 288, 289, 298, 302, 303, 310, 311, 312, 320, 324, 328; Violet dyes such as C.I.Disperse Violet 1, 4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77; Green dyes such as C.I.Disperse Green 6:1, 9; Brown dyes such as C.I.Disperse Brown 1, 2, 4, 9, 13, 19, 21, 27; Blue dyes such as C.I.Disperse Blue 3, 7, 9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71, 72, 73, 75, 79, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 154, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 330, 333, 359, 360, etc.; Black dyes such as C.I.Disperse Black 1, 3, 10, 24, etc. can preferably be used.

[0051] As dyes manufactured by Nippon Kayaku Co., Ltd., Kayaset Black K-R, A-N, Kayalon Polyester Black S-200, EX-SF 300, G-SF, BR-SF, 2B-SF 200, TA-SF 200, AUL-S, Kayaset Yellow K-CL, Kayalon Polyester Yellow 4G-E, Kayalon Polyester Light Yellow 5G-S, Kayaset Red K-BL, Kayacelon Red E-BF, SMS-5, SMS-12, Kayalon Polyester Red TL-SF, BR-S, BL-E, HL-SF, 3BL-S200, AUL-S, Kayalon Polyester Light Red B-S200, Kayalon Polyester Rubine BL-S200, Kayaset Blue N, K-FL, MSB-13, Kayalon Polyester Blue BR-SF, T-S, Kayalon Polyester Light Blue BGL-S200, Kayalon Polyester Turq Blue GL-S200, Kayalon Polyester Blue Green FCT-S, etc. can be preferably used. As dyes manufactured by Orient Chemical Industries Co., Ltd., Valifast Black 3806, 3810, 3820, Oil Black BS, BY, B-85, 860, Water Yellow 6C, Valifast Yellow 1101, 1105, 3110, 3120, 4120, 4126, Oplas Yellow 130, 140, Oil Yellow GG-S, 105, 107, 129, 818, Water Red 27, Valifast Red 1306, 1355, 2303, 3311, 3320, Valifast Orange 3210, Valifast Brown 2402, Oil Red 5B, Oil Pink 312, Oil Brown BB, Valifast Blue 1601, 1603, 1605, 2606, 3806, 3820, Oil Blue #15, #613, 613, N14, BOS, etc. can be preferably used. As dyes manufactured by Sumitomo Chemical Co., Ltd., Sumikaron Black S-BL, S-BF extra conc., S-RPD, S-XE 300%, Sumikaron Yellow SE-4G, SE-5G, SE-3GL conc., SE-RPD, Sumikaron Brilliant Flavine S-10G, Sumikaron Red E-FBL, E-RPD(E), S-RPD(S), Sumikaron Brilliant Red S-BF, S-BLF, SE-BL, SE-BGL, SE-2BF, SE-3BL(N), Sumikaron Red E-FBL, E-RPD(E), S-RPD(S), Sumikaron Brilliant Red S-BF, S-BLF, SE-BL, SE-BGL, SE-2BF, SE-3BL(N), Sumikaron Brilliant Blue S-BL, Sumikaron Turquoise Blue S-GL, S-GLFgrain, etc. can be preferably used. As dyes manufactured by BASF, Basacryl Black X-BGW, NaozaponBlack X-51, X-55, Neozapon Yellow 081, Lurafix Yellow 138, etc., Zapon Blue 807, Neozapon Blue 807, Lurafix Blue590, 660, Orasol Black RLI, RL, CN, Oracet Yellow 8GF, GHS, Orasol Red G, Oracet Pink RP, Orasol Blue GL, GN, 2R, etc. can be preferably used. As dyes manufactured by Tago Chemical Industry Co., Ltd., Oleosol Fast Black AR, RL, Oleosol Fast Pink FB, Rhodamine A, B, B gran., Oleosol Fast Yellow 2G, Oleosol Fast Blue ELN, etc. can be preferably used. As dyes manufactured by Hodogaya Chemical Co., Ltd., Spilon Black BNH, MH special, etc. can be preferably used. As dyes manufactured by Mitsui Chemicals, Inc., PS Yellow GG, MS Yellow HD-180, PS Red G, MS Magenta VP, etc. can be preferably used. As dyes manufactured by Bayer AG, Ceres Blue GN 01, etc. can be preferably used. As dyes manufactured by Sumika Color Co., Ltd., TS Yellow 118 cake, ESC Yellow 155, Sumiplast Yellow HLR, GC, TS Turq Blue 618, 606, ESC Blue 655, 660, Sumiplast BlueS, OA, etc. can be preferably used.

[0052] The pigments are not particularly limited and known ones can be used. Examples of organic pigments include azo pigments such as soluble azo pigments, insoluble azo pigments, and condensed azo pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, diketopyrrolopyrrole pigments and other polycyclic pigments, phthalocyanine pigments, etc. Examples of inorganic pigments include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, metal chlorides, etc. Further, examples of carbon black include furnace black, lamp black, acetylene black, channel black, etc.

[0053] Specific examples of the pigments include red pigments such as C.I.Pigment Red 7, 9, 14, 41, 48:1, 48:2, 48:3, 48:4, 81:1, 81:2, 81:3, 122, 123, 146, 149, 168, 177, 178, 179, 187, 200, 202, 208, 210, 215, 224, 254, 255, 264; Yellow pigments such as C.I.Pigment Yellow 1, 3, 5, 6, 14, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 93, 97, 98, 104, 108, 110, 128, 138, 139, 147, 150, 151, 154, 155, 166, 167, 168, 170, 180, 188, 193, 194, 213; Orange pigments such as C.I.Pigment Orange 36, 38, 43; Blue pigments such as C.I.Pigment Blue 15, 15:2, 15:3, 15:4, 15:6, 16, 22, 60; Green pigments such as C.I.Pigment Green 7, 36, 58; Violet pigments such as C.I.Pigment Violet 19, 23, 32, 50; Examples of black pigments include C.I.Pigment Black 7. Among these, C.I.Pigment Red 122, C.I.Pigment Yellow 74, 128, 155, C.I.Pigment Blue 15:3, 15:4, 15:6, C.I.Pigment Green 7, 36, C.I.Pigment Violet 19, C.I.Pigment Black 7, etc. can be preferably used.

[0054] The disperse dyes and / or pigments contained in the dispersion can be appropriately selected in terms of type, particle size, treatment method, etc. according to the purpose. Also, for the disperse dyes and pigments contained in the dispersion, only one type may be used, or two or more types may be used.

[0055] The concentration of the disperse dyes and pigments in the dispersion is preferably 1 to 50% by mass, more preferably 5 to 50% by mass in 100% by mass of the dispersion. When the concentration of the disperse dyes and pigments exceeds 50% by mass, in the dispersion, the density of the disperse dyes and pigments becomes high, and free movement is hindered, which may cause aggregation.

[0056] The aqueous solvent can be water and / or a water-soluble organic solvent, and two or more thereof can be mixed and used. It is preferable to use pure water or ion-exchanged water (deionized water) as the water. Examples of the water-soluble organic solvent include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; glycols such as ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether; polyhydric alcohols such as glycerin; and nitrogen-containing compounds such as N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone. The proportion of water and the water-soluble organic solvent in the dispersion is preferably 5 to 95% by mass, more preferably 30 to 90% by mass, based on 100% by mass of the dispersion.

[0057] Regarding the method for producing the dispersion of the present invention, it is particularly preferable to include a step of mixing and dispersing the above-described dispersant, the disperse dye and / or the pigment, and the aqueous solvent. For example, the dispersant, the disperse dye and / or the pigment, and the aqueous solvent can be mixed using a mixing and dispersing machine such as a paint shaker, a bead mill, a ball mill, a dissolver, a kneader to obtain a dispersion. When using a solid component at room temperature, heating and mixing may be performed as necessary.

[0058] The static surface tension of the dispersion is desirably 60 mN / m or less, more desirably 50 mN / m or less.

[0059] The viscosity of the dispersion is desirably 50.0 mPa·s or less, more desirably 30.0 mPa·s or less. Further, as the lower limit value of the viscosity of the dispersion, it is desirable to be 1.0 mPa·s or more. The viscosity in this case is the condition at 25°C.

[0060] Regarding the average particle diameter of the disperse dye and / or pigment in the dispersion, although it depends on the type of the disperse dye and / or pigment, it is desirably 500 nm or less, more desirably 300 nm or less. The average particle diameter referred to here means the median diameter (D50).

[0061] Further, the dispersion of the present invention is excellent in dispersion stability, and the interfacial migration rate is desirably 3.0 μm / s or less. More preferably, it is 1.0 μm / s or less.

[0062] The dispersion of the present invention is excellent in redispersibility. That is, inks containing colorants insoluble in water such as disperse dyes and pigments, when in a dried state, the dispersed state of the disperse dyes and pigments is broken and aggregation occurs. Generally, the disperse dyes and pigments in the ink once aggregated cannot return to the dispersed state again even when a liquid medium such as water is added, and the redispersibility often deteriorates. However, in the present invention, the redispersibility is excellent. In the present invention, the elution rate of the dispersion in the dispersion medium is preferably 40% or more, more preferably 60% or more. The elution rate of the dispersion in the dispersion medium will be described in the examples below.

[0063] The ink composition of the present invention contains the dispersion of the present invention described above, and further optionally contains a resin and other additives. That is, the ink composition of the present invention comprises the following (i) to (v) (i) Dispersant (ii) Disperse dye and / or pigment (iii) Water and / or water-soluble organic solvent (iv) Resin (v) One or more additives selected from the group consisting of an ultraviolet absorber, an antioxidant, a pH adjuster, a preservative, and a viscosity adjuster It is preferably contained.

[0064] The concentration of the disperse dye and / or pigment in the ink composition is preferably 0.1 to 20% by mass, more preferably 0.1 to 10% by mass, based on 100% by mass of the ink composition.

[0065] The proportion of water and / or water-soluble organic solvent in the ink composition is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, based on 100% by mass of the ink composition.

[0066] The resin contained in the ink composition is preferably a polymer having a hydrophobic group and a hydrophilic group. This polymer preferably has at least one functional group selected from an alkyl group, a cycloalkyl group, and an aryl group as the hydrophobic group. Further, it preferably has at least one functional group selected from a carboxy group, a sulfo group, a hydroxy group, an amino group, an amide group, and these functional groups as the hydrophilic group. Such a polymer can be obtained, for example, by polymerizing monomers and oligomers having functional groups such as acryloyl group, methacryloyl group, vinyl group, and allyl group.Specifically, styrene, tetrahydrofurfuryl acrylate, butyl methacrylate, (α, 2, 3 or 4)-alkylstyrene, (α, 2, 3 or 4)-alkoxystyrene, 3,4-dimethylstyrene, α-phenylstyrene, divinylbenzene, vinylnaphthalene, dimethylamino (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropylacrylamide, N,N-dimethylaminoethyl acrylate, acryloylmorpholine, N,N-dimethylacrylamide, N-isopropylacrylamide, N,N-diethylacrylamide, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, ethylhexyl (meth)acrylate, other alkyl (meth)acrylates, methoxydiethylene glycol (meth)acrylate, diethylene glycol or polyethylene glycol (meth)acrylate with ethoxy group, propoxy group, butoxy group, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, hydroxyalkyl (meth)acrylate, other fluorine-containing, chlorine-containing, silicon-containing (meth)acrylates, (meth)acrylamide, maleic amide, (meth)acrylic acid, etc. When introducing a crosslinked structure in addition to monofunctional ones, compounds having acrylic groups or methacrylic groups such as (mono, di, tri, tetra, poly)ethylene glycol di(meth)acrylate, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol (meth)acrylates, trimethylolpropane tri(meth)acrylate, glycerin (di, tri)(meth)acrylate, di(meth)acrylate of ethylene oxide adduct of bisphenol A or F, neopentyl glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc. can be used.

[0067] The proportion of the resin in the ink composition is not particularly limited, but it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, in 100% by mass of the ink composition. When the resin is blended in the ink composition, it is preferably 1% by mass or more.

[0068] In addition, various additives can be contained in the ink composition. Examples of the additives include ultraviolet absorbers, antioxidants, pH adjusters, preservatives, viscosity adjusters, etc., and these can be appropriately selected and blended into the ink composition. These additives, apart from the disperse dyes and / or pigments, water and / or water-soluble organic solvents, and resins, are the balance in the dispersion and the ink composition in 100% by mass, specifically, they can be blended at a ratio of 0 to 10% by mass in 100% by mass of the ink composition.

[0069] Also, regarding the method for producing the ink composition, there is no particular limitation, but the following steps (a) and (b), (a) A step of mixing and dispersing the above-described dispersant, disperse dyes and / or pigments, and an aqueous solvent to obtain a dispersion; (b) A step of mixing the above dispersion with at least one substance selected from the group consisting of water, water-soluble organic solvents, resins, ultraviolet absorbers, antioxidants, pH adjusters, preservatives, and viscosity adjusters It is preferable to adopt a method including these steps.

[0070] The ink composition is applied to a recording medium by an inkjet recording method, a recording method using a writing instrument such as a pen, or other printing methods. The ink composition of the present invention can be preferably used particularly in the inkjet recording method.

Examples

[0071] (A) A styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer was synthesized by a known and commonly used method as follows. Unless otherwise specified, in this production example, "parts" is used in the meaning of "parts by mass", and "%" is used in the meaning of "% by mass".

[0072] <Production Example 1> [Production of Aqueous Polymer Solution Neutralized with Sodium Hydroxide] Into a three-necked flask equipped with a thermocouple thermometer, a stirrer, and a reflux tube, 33 parts of styrene (hereinafter referred to as ST), 44 parts of methyl methacrylate (hereinafter referred to as MMA), 33 parts of polyethylene glycol methacrylate (average number of moles of EO added: 23, "Blemmer PME-1000" manufactured by NOF Corporation; hereinafter referred to as PEG(23)MA), 55 parts of methacrylic acid (hereinafter referred to as MAA), 3.3 parts of n-dodecyl mercaptan (hereinafter referred to as NDM) as a chain transfer agent, 1.65 parts of 2,2'-azobis-isobutyronitrile (hereinafter referred to as AIBN) as a polymerization initiator, and 169.95 parts of 2-propanol (hereinafter referred to as IPA) as a solvent were charged. After that, the operation of deoxygenation and nitrogen substitution was repeated twice to make the inside of the flask a nitrogen atmosphere. Then, stirring was started and the temperature was raised until the internal temperature reached 80°C. The internal temperature was maintained at 80°C for 6 hours while continuing stirring. After 6 hours, 145.2 parts of IPA were slowly added, and then the internal temperature was cooled to 25°C or lower to obtain an unneutralized polymer (IPA solution) (hereinafter referred to as unneutralized solution A). The polymer content determined from the dry residue of the obtained unneutralized solution A was 35.2%. Also, the weight average molecular weight of the unneutralized polymer was 18,275, and the number average molecular weight was 6,991.

[0073] In the present invention, the above weight average molecular weight and number average molecular weight were measured by gel permeation chromatography (GPC) under the following conditions for a solution obtained by dissolving an unneutralized polymer solution in tetrahydrofuran to a polymer content of 1% after drying at 105°C for 3 hours and then filtering with a 0.45 μm membrane filter, and are values in terms of standard polystyrene conversion. · Column: Shodex KF-802, Shodex KF806M (manufactured by Showa Denko KK) · Elution solvent: Tetrahydrofuran · Flow rate: 1.0 mL / min · Injection volume: 10 μL · Column temperature: 40°C · Detector: RI detector

[0074] 140 parts of unneutralized solution A were weighed into a beaker and stirring was started. 6.0 parts of sodium hydroxide (partition coefficient = -3.88, boiling point 1390 °C) were weighed into another beaker, 150 parts of ion-exchanged water were added to prepare an aqueous sodium hydroxide solution. By adding the total amount of the prepared aqueous sodium hydroxide solution to the unneutralized solution A under stirring, the polymer was neutralized, and the entire amount of the liquid was transferred to an eggplant flask. After distilling off 120 parts using a rotary evaporator, 200 parts of ion-exchanged water were added, and further 160 parts were distilled off under reduced pressure to remove IPA from the solution. 31.64 parts of ion-exchanged water were added to make the total amount 252.80 parts, and an aqueous sodium hydroxide-neutralized polymer solution with 19.5% polymer content and pH 7.4 was obtained.

[0075] <Production Example 2, Comparative Production Example 1> The type of neutralizing agent for the unneutralized solution A was changed as shown in Table 1, and the amount of neutralizing agent added was changed to the amount corresponding to the pH shown in the table. Otherwise, it was produced in the same manner as in Production Example 1. The types of neutralizing agents in Table 1 are as follows. · Sodium hydroxide (partition coefficient = -3.88, boiling point 1390 °C) · 2-Amino-2-methyl-1-propanol (partition coefficient = -0.74, boiling point 166 °C) · Ammonia (partition coefficient = 0.23, boiling point -33 °C)

[0076] <Production Example 3, Comparative Production Example 2> It was produced in the same manner as in Production Example 1 except that the content (charging ratio) of each component was changed as shown in Table 1. Furthermore, the neutralizing agent for the unneutralized solution in Production Example 3 was changed as shown in Table 1 to produce Comparative Production Example 2.

[0077] <Comparative Production Example 3> Into a three-necked flask equipped with a thermocouple thermometer, a stirrer, and a reflux tube, 135.3 parts of ST135, 13.2 parts of polyethylene glycol methacrylate (average number of moles of EO added: 9, manufactured by NOF Corporation, "Blemmer PME-400". Hereinafter referred to as PEG(9)MA), 16.5 parts of vinylsulfonic acid (hereinafter referred to as VSA), 3.3 parts of NDM, 1.65 parts of AIBN, 305.25 parts of N,N-dimethylformamide (hereinafter referred to as DMF), and 49.5 parts of ion-exchanged water were charged. After that, the operation of deoxygenation and nitrogen substitution was repeated twice to make the atmosphere in the flask a nitrogen atmosphere. Then, stirring was started, VSA and AIBN were dissolved, and the mixture was heated until the internal temperature reached 80°C. While maintaining the internal temperature at 80°C for 6 hours, stirring was continued to carry out the polymerization reaction. After the reaction was completed, the reaction solution was dropped into IPA to precipitate the polymer. After removing the supernatant, the precipitate was recovered and dried to obtain unneutralized polymer B. The weight-average molecular weight of the obtained unneutralized polymer B was 18,517. 15 parts of unneutralized polymer B and 70 parts of ion-exchanged water were weighed into a separable flask equipped with a thermocouple thermometer, a stirrer, a reflux tube, and a pH electrode, and heated with stirring until the internal temperature reached 80°C. Sodium hydroxide was added here until the pH reached 8.0, and further ion-exchanged water was added to make the total amount 100 parts. Stirring was continued at 80°C for 3 hours. The unneutralized polymer B did not dissolve.

[0078] <Comparative Production Examples 4 and 5> The neutralizing agent type of unneutralized polymer B was changed as shown in the table, and the production was carried out in the same manner as in Comparative Production Example 3 except that the addition amount of the neutralizing agent was changed to the amount that made the pH as shown in the table. In all cases, stirring was continued at 80°C for 3 hours, but the unneutralized polymer B did not dissolve.

[0079]

Table 1

[0080]

Table 2

[0081] Hereinafter, examples and comparative examples are shown to specifically describe the present invention, but the present invention is not limited to the following examples. In the following examples, "parts" and "%" indicate parts by mass and mass%, respectively.

[0082] [Example 1] 15 parts of Hostaperm Blue BT-617-D (manufactured by CLARIANT, Pigment Blue15:4), which is a blue pigment, 61.9 parts of ion-exchanged water as an aqueous solvent, 23.1 parts of the dispersant, and 300 parts of zirconia beads (diameter 0.3 mm) were placed in a plastic container (made of polypropylene, capacity 0.5 L), and dispersed for 1 hour using a PAINT SHAKER (manufactured by Asada Iron Works Co., Ltd.). After dispersion, the zirconia beads were filtered off to obtain a dispersion.

[0083] [Examples 2, 3, Comparative Examples 1 - 5] In the same manner as in Example 1, dispersions of each example having the compositions shown in Table 3 below were prepared.

[0084] For each dispersion, its surface tension, viscosity, average particle size, dispersion stability, redispersibility (visual), and redispersibility - elution rate were measured by the following methods. The results are shown in Table 3.

[0085] <Surface tension> Using a DY-500 high-performance surface tension meter (manufactured by Kyowa Interface Science Co., Ltd.), the static surface tension of the dispersion immediately after dispersion was measured at 25°C.

[0086] <Viscosity> Using a TVE-20 E-type viscometer (manufactured by Toki Sangyo Co., Ltd.), the viscosity (25°C) of the dispersion immediately after dispersion was measured.

[0087] <Average particle size> Using an ELSZ-2000 zeta potential - particle size - molecular weight measurement system (manufactured by Otsuka Electronics Co., Ltd.), the average particle size (D50) of the dispersion immediately after dispersion was measured.

[0088] <Dispersion stability> The dispersion stability was evaluated using a dispersion stability analyzer LUMiSizer (manufactured by LUM). This analysis was carried out under the conditions of a temperature of 25 °C immediately after dispersion, a rotation speed of 4,000 rpm, and an analysis time of 50 minutes, and the interface movement speed (particle sedimentation speed) was measured. The smaller the interface movement speed, the better the dispersion stability.

[0089] <Redispersibility (visual inspection)> 100 μL of the dispersion immediately after dispersion was measured with a micropipette and placed in a petri dish, and left to stand and dry at room temperature (about 25 °C) for about 15 hours. After drying, 3 mL of ion-exchanged water was added, and the state of redispersion of the dried dispersion in the ion-exchanged water was visually determined. The evaluation criteria for redispersibility are shown below. (Evaluation criteria) ◎: The dried matter disappeared and redispersed. 〇: Part of the dried matter remained, but it was generally redispersed. △: Most of the dried matter remained and was partially redispersed. ×: Redispersion of the dried matter could not be confirmed.

[0090] <Redispersibility dissolution rate> 100 μL of the dispersion immediately after dispersion was measured with a micropipette and placed in a petri dish, and left to stand and dry at room temperature (about 25 °C) for about 15 hours. After drying, the mass of the dried dispersion (mass before redispersion) was measured with an electronic balance, then 3 mL of ion-exchanged water was added, and it was left to stand for 3 minutes under the condition of room temperature (about 25 °C). After standing, the undissolved matter was removed using an 80-mesh filter cloth, and the obtained filtrate was dried in a dryer at 60 °C for 3 hours. After drying, the dried matter (redispersed mass) returned to room temperature was measured with an electronic balance, and the dissolution rate of the dispersion in ion-exchanged water was calculated using the following formula [1]. Redispersibility dissolution rate [%] = (redispersed mass) / (mass before redispersion) × 100 ··· [1]

[0091]

Table 3

[0092] From Table 3 above, it can be seen that by changing from "ammonia neutralization in Comparative Production Example 1" to "sodium hydroxide neutralization in Production Example 1" and "2-amino-2-methyl-1-propanol neutralization in Production Example 2", the elution rate can be improved by about 40%. Furthermore, by changing from "ammonia neutralization in Comparative Production Example 2" to "sodium hydroxide neutralization in Production Example 3", the elution rate can be improved by about 20%. Therefore, by using a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer neutralized with a basic compound having an octanol / water partition coefficient of -5.0 or more and 0 or less as a dispersant, a dispersion excellent in redissolution property can be obtained.

Claims

1. (A) A styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a weight average molecular weight of 1,000 to 50,000, containing a copolymer in which the content of (a1) styrene is 1 to 40% by mass, and having a surfactant content of less than 0.1% by mass, characterized as a dispersant.

2. The component (A) is the following (a1) to (a3), (a1) Styrene: 1 to 40% by mass (a2) An ethyleneoxy group-containing (meth)acrylic acid alkyl ester monomer: 1 to 59% by mass (a3) Monomers other than (a1) to (a2): 1 to 98% by mass The dispersant according to Claim 1, which is a polymer of these.

3. The dispersant according to Claim 2, wherein the monomer of the component (a3) includes a radically polymerizable monomer containing at least one functional group.

4. The dispersant according to Claim 1 or 2, wherein the component (A) is a neutralized product with a basic compound having an octanol / water partition coefficient of -5.0 or more and 0 or less.

5. The dispersant according to Claim 1 or 2, which does not contain an acetylene-based surfactant.

6. The dispersant according to Claim 1 or 2, which is for aqueous solvent dispersion of a disperse dye or a pigment.

7. A dispersion containing a dispersant, a disperse dye and / or a pigment, and an aqueous solvent, wherein the dispersant is the dispersant according to Claim 1 or 2.

8. An ink composition characterized by containing the dispersion according to Claim 7.

9. A method for producing the dispersant according to Claim 1 or 2, wherein the component (A) includes a neutralization step with a basic compound having an octanol / water partition coefficient of -5.0 or more and 0 or less.

10. A method for producing a dispersion, including a step of mixing and dispersing the dispersant according to Claim 1 or 2, a disperse dye and / or a pigment, and an aqueous solvent.

11. The following steps (a) and (b) (a) A step of mixing and dispersing the dispersant according to Claim 1 or 2, a disperse dye and / or a pigment, and an aqueous solvent to obtain a dispersion; and (b) A step of mixing the dispersion with at least one substance selected from the group consisting of water, a water-soluble organic solvent, a resin, an ultraviolet absorber, an antioxidant, a pH adjuster, a preservative, and a viscosity adjuster. A method for producing an ink composition, characterized by including these steps.

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