Dispersant, dispersion, and ink composition, and production methods therefor

Abstract

To provide a dispersant capable of dispersing a disperse dye or pigment even when added in a small amount and exhibiting wetting properties, a dispersion exhibiting re-dispersibility and excellent dispersion stability for a disperse dye or pigment, an ink composition comprising the same, and production methods therefor.SOLUTION: The present invention provides a dispersant characterized by comprising (A) a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a molecular weight distribution (Mw / Mn) of 2.0 or less and a weight average molecular weight of 1,000 to 50,000, where the copolymer has a styrene (a1) content of 1 to 40 mass%; a dispersion; and an ink composition, as well as production methods therefor.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Disperse dyes and pigments have traditionally been used as colorants in inks. When using disperse dyes or pigments in inks, the finely divided disperse dyes or pigments must be dispersed in water. However, because disperse dyes and pigments are insoluble in water, it is important to keep the disperse dyes and pigments in a dispersed state and keep them stable for a long period of time.

[0003] Furthermore, inks containing water-insoluble colorants such as disperse dyes and pigments have the drawback that when they lose their moisture and dry out due to some factor, the dispersion state of the pigment breaks down, causing the pigment to aggregate. Once aggregated in this way, the disperse dyes and pigments in the ink cannot be returned to a dispersed state even by adding a liquid medium such as water (poor redispersibility), and there is a strong demand for an improvement in this regard.

[0004] Nonionic surfactants, anionic surfactants, polymer surfactants, and the like have been proposed as dispersants for inks. For example, Patent Documents 1 and 2 disclose that nonionic surfactants containing an acetylene group are useful as pigment dispersants. However, although nonionic surfactants containing an acetylene group are excellent in ink penetration and foam suppression, they have inferior dispersing ability compared to other dispersants, requiring longer dispersion times, and no redispersion effect can be expected.

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

[0006] Furthermore, Patent Documents 4 and 5 disclose that pigment dispersions using acrylic polymers improve the redispersibility of inks, but the process is complicated, requiring crosslinking of the polymer in the aqueous pigment dispersion, etc. Therefore, there is a need for the development of dispersants that can be expected to have a redispersion effect more easily.

[0007] Furthermore, Patent Document 6 discloses a dispersion resin containing a hydrophobic monomer, an acrylic monomer, and a hydrophilic vinyl monomer having a sulfonic acid group, but because the proportion of hydrophobic monomer is high, the dispersion effect may not be achieved in aqueous inks.

[0008] Patent Document 7 discloses that an inkjet ink using a styrene-(meth)acrylic acid copolymer in combination with a specific acetylene glycol compound has high-quality and stable recording performance, and is capable of increasing the print density on the surface of a fabric while maintaining the storage stability of the ink, but does not explicitly state redispersibility after drying.

[0009] The present inventors have also previously filed a patent application for an invention relating to a dispersant that combines a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer with an acetylene surfactant (Japanese Patent Application No. 2022-155738). While this dispersant can exhibit redispersibility, this effect is only achieved by using the two components in combination, so there was room for further improvement in the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-290578 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-020673 [Patent Document 3] International Publication No. 2013 / 008691 [Patent Document 4] Japanese Patent Application Publication No. 2019-210389 [Patent Document 5] Japanese Patent Application Publication No. 2019-014879 [Patent Document 6] Japanese Patent Publication No. 2022-052994 [Patent Document 7] International Publication No. 2014 / 129323 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above circumstances, and aims to provide a dispersant that can disperse disperse dyes and pigments even in a small amount and that can exhibit wettability, a dispersion that exhibits re-dispersibility and has excellent dispersion stability for disperse dyes and pigments, an ink composition using the same, and methods for producing the same. [Means for solving the problem]

[0012] As a result of extensive research conducted by the present inventors to achieve the above object, they have found that when a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a molecular weight distribution (Mw / Mn) of 2.0 or less is used as a dispersant, the addition of a small amount of the copolymer exhibits dispersibility, wettability, and redispersibility, is excellent in terms of microparticulation of disperse dyes and pigments, and further improves the dispersion stability of disperse dyes and pigments, thereby completing the present invention.

[0013] Accordingly, the present invention provides the following dispersants, dispersions and ink compositions, as well as methods for producing these. 1. A dispersant characterized by containing (A) a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a molecular weight distribution (Mw / Mn) of 2.0 or less and a weight average molecular weight of 1,000 to 50,000, and (a1) a copolymer having a styrene content of 1 to 40 mass%. 2. The component (A) is selected from the following (a1) to (a3): (a1) Styrene: 1 to 40% by mass (a2) Ethyleneoxy group-containing (meth)acrylic acid ester monomer: 1 to 59 mass% (a3) ​​Monomer other than (a1) to (a2): 1 to 98 mass% 2. The dispersant according to 1 above, which is a polymer of the following: 3. The dispersant according to 2 above, wherein the monomer of component (a3) ​​comprises a radical polymerizable monomer containing at least one functional group. 4. The dispersant according to 1 or 2 above, which is used to disperse disperse dyes or pigments in aqueous solvents. 5. A dispersion comprising a dispersant, a disperse dye and / or pigment, and an aqueous solvent, wherein the dispersant is the dispersant described in 1 or 2 above. 6. An ink composition comprising the dispersion described in 5 above. 7. A method for producing the dispersant according to 1 or 2 above, comprising a step of synthesizing the component (A), a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer, by living radical polymerization. 8. A method for producing a dispersion, comprising the step of mixing and dispersing the dispersant according to 1 or 2 above, a disperse dye and / or pigment, and an aqueous solvent. 9. The following steps (a) and (b) (a) a step of mixing and dispersing the dispersant described in 1 or 2 above, a disperse dye and / or pigment, and an aqueous solvent to obtain a dispersion; (b) 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, comprising: [Effects of the Invention]

[0014] The dispersant of the present invention can disperse disperse dyes and pigments with a small amount added, regardless of the type of disperse dye or pigment. Furthermore, dispersions and ink compositions using this dispersant exhibit excellent wettability and redispersibility, as well as excellent dispersion stability. DETAILED DESCRIPTION OF THE INVENTION

[0015] The dispersant of the present invention contains (A) a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a molecular weight distribution (Mw / Mn) of 2.0 or less and a weight average molecular weight of 1,000 to 50,000.

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

[0017] The content of styrene as the component (a1) is 1 to 40% by mass, preferably 10 to 30% by mass, relative to 100% by mass of the monomers of the components (a1) to (a3). By keeping this content within the range of 1 to 40% by mass, the dispersion can be made more redispersible.

[0018] The ethyleneoxy group-containing (meth)acrylic acid ester monomer, which is the component (a2), preferably has an added mole number of ethyleneoxy groups 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 ester monomer, component (a2), is preferably 100 to 5,000.

[0020] Specific examples of the component (a2) include acrylic acid 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, and polyethylene glycol-propylene glycol-mono(meth)acrylate. Polyethylene glycol mono(meth)acrylate is particularly preferred.

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

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

[0023] The content of the ethyleneoxy group-containing (meth)acrylic acid ester monomer of the component (a2) is 1 to 59% by mass, preferably 5 to 55% by mass, relative to 100% by mass of the monomers (a1) to (a3). By keeping the content of the component (a2) within the range of 1 to 59% by mass, the effect of dispersing disperse dyes and pigments can be obtained when used as a dispersant.

[0024] The monomers other than (a1) and (a2) of the component (a3) ​​are not particularly limited, but examples include (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 types, but it is preferable to contain at least one radical polymerizable monomer containing a functional group such as a carboxy group, amide group, hydroxy group, epoxy group, and sulfonic acid group. Particularly preferred 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 is not particularly limited and may be one having a linear or branched structure, one having an alicyclic group, or one having an aromatic ring group, but does not include the ethyleneoxy group-containing (meth)acrylic acid ester monomer that is the above-mentioned 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, and stearyl (meth)acrylate.

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

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

[0029] Examples of the carboxy group-containing radically polymerizable monomer 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, and itaconic acid butyl ester.

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

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

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

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

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

[0035] The content of monomers other than components (a1) and (a2) is 1 to 98% by mass, preferably 10 to 80% by mass, relative to 100% by mass of the monomers (a1) to (a3). If this content is less than 1% by mass, it becomes difficult to make the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer water-soluble, while if it exceeds 98% by mass, the effect of imparting redispersibility to the dispersion may be impaired.

[0036] The monomers of components (a1) to (a3) ​​can be polymerized by known polymerization methods, and are not particularly limited, but living radical polymerization is preferred. Living radical polymerization is preferred in that it maintains the simplicity and versatility of conventional radical polymerization methods, while allowing growth without being hindered by side reactions that deactivate the growing ends, making it easy to precisely control the molecular weight distribution and produce polymers with uniform composition.

[0037] Living radical polymerization methods vary depending on the method used to stabilize the growing polymer chain. These include methods using compounds capable of generating nitroxide radicals (nitroxide method / NMP method); methods using metal complexes such as copper or ruthenium to initiate polymerization with halogenated compounds (ATRP method); methods using dithiocarboxylic acid esters or xanthates (RAFT method); methods using organotellurium compounds (TERP method); methods using organic iodine compounds (ITP method); and methods using iodine compounds as initiators and organic compounds such as phosphorus compounds, nitrogen compounds, oxygen compounds, or hydrocarbons as catalysts (reversible transfer catalyzed polymerization; RTCP method, reversible catalyst-mediated polymerization; RCMP method). RAFT polymerization is particularly preferred.

[0038] For example, in the case of solution polymerization, the target styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer can be obtained by charging an organic solvent and monomers into a reactor, adding a polymerization initiator, and copolymerizing, preferably by heating. The method for charging each raw material may be batchwise initial lump-sum charging in which all raw materials are charged at once, semi-continuous charging in which at least some raw materials are continuously fed into the reactor, or continuous polymerization in which all raw materials are continuously fed and the product is continuously withdrawn from the reactor at the same time.

[0039] In the RAFT method, polymerization proceeds via a reversible chain transfer reaction in the presence of a chain transfer agent (RAFT agent) and a radical polymerization initiator. Various known RAFT agents, such as compounds having a thiocarbonylthio group, can be used, including dithioester compounds, xanthate compounds, trithiocarbonate compounds, and dithiocarbamate compounds. Preferably, a RAFT agent containing a trithiocarbonate group is used. Examples of compounds having a trithiocarbonate group include S,S-dibenzyltrithiocarbonate, bis[4-(2,3-dihydroxypropoxycarbonyl)benzyl]trithiocarbonate, bis[4-(2-hydroxyethoxycarbonyl)benzyl]trithiocarbonate, and 1,4-bis(alkylsulfanylthiocarbonylsulfanylmethyl)benzene (e.g., 1,4-bis(n-dodecylsulfanylthiocarbonylsulfanylmethyl)benzene). In the polymerization reaction, the amount of the RAFT agent used is adjusted appropriately depending on the types of monomers and RAFT agent used, etc.

[0040] Radical polymerization initiators used in polymerization using the RAFT method can include known radical polymerization initiators such as azo compounds, organic peroxides, and persulfates. Among these, azo compounds are preferred because they are safe and easy to handle and are less likely to cause side reactions during radical polymerization. Specific examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 2,2'-azobis(N-butyl-2-methylpropionamide). The radical polymerization initiator may be used alone or in combination of two or more kinds.

[0041] The amount of radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining a polymer with a narrower molecular weight distribution, it is preferably 0.5 mol or less, more preferably 0.4 mol or less, per mol of RAFT agent. Furthermore, from the viewpoint of stably carrying out the polymerization reaction, the lower limit of the amount of radical polymerization initiator used is preferably 0.01 mol or more, more preferably 0.05 mol or more, per mol of RAFT agent. The amount of radical polymerization initiator used per mol of RAFT agent is preferably 0.01 to 0.5 mol, more preferably 0.05 to 0.4 mol.

[0042] The polymerization reaction is preferably carried out in a solvent using a polymerization solvent known in living radical polymerization. The polymerization solvent used is preferably an organic solvent capable of dissolving the monomers, and examples thereof include aromatic compounds such as benzene, toluene, xylene, and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone compounds such as acetone, methyl ethyl ketone, and cyclohexanone; dimethylformamide, acetonitrile, dimethyl sulfoxide, and alcohol. Water may also be used as the polymerization solvent. The polymerization solvent may be used alone or in combination of two or more. Alternatively, a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer may be produced by bulk polymerization or the like without using a polymerization solvent.

[0043] When the polymerization reaction is carried out in a solvent, the amount of the polymerization solvent used is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass, per 100 parts by mass of the total amount of the monomers used in the reaction. When the amount of the polymerization solvent used is 100 parts by mass or less, it is preferable because a high reaction rate can be achieved in a short time.

[0044] In the polymerization reaction by the RAFT method, the reaction temperature is preferably 40 to 100°C, more preferably 45 to 90°C, and even more preferably 50 to 80°C. A reaction temperature of 40°C or higher is preferred because it allows the polymerization reaction to proceed smoothly, while a reaction temperature of 100°C or lower is preferred because it prevents side reactions and alleviates restrictions on the initiators and solvents that can be used. The reaction time can be set appropriately depending on the monomers used, etc., but is preferably 1 to 48 hours, and more preferably 2 to 24 hours.

[0045] The polymerization reaction may be carried out, if necessary, in the presence of a chain transfer agent such as an alkylthiol compound having 2 to 20 carbon atoms. When a polymer solution is obtained by the above polymerization, the polymer can be isolated by subjecting the polymer solution to a known solvent removal treatment. Alternatively, the obtained polymer solution may be used directly in the next reaction step. Furthermore, if necessary, a dehydrating agent such as trimethyl orthoacetate or triethyl orthoacetate may be mixed into the reaction system. By adding a dehydrating agent to the reaction system, the progress of the crosslinking reaction during polymerization can be suppressed.

[0046] For example, when obtaining a block copolymer, a method including the following three polymerization steps is preferred because it allows the target product to be obtained efficiently. That is, in the first polymerization step, polymer block (A) is obtained using the monomers that constitute polymer block (A), and then in the second polymerization step, monomers that constitute polymer block (B) are polymerized to obtain polymer block (B). This results in an (A)-(B)-(A) triblock copolymer consisting of polymer block (A) / polymer block (B) / polymer block (A). Furthermore, in the third polymerization step, the monomers that constitute polymer block (A) are polymerized to obtain polymer block (A). This results in an (A)-(B)-(A)-(B)-(A) pentablock copolymer consisting of polymer block (A)-polymer block (B)-polymer block (A)-polymer block (B)-polymer block (A) as a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer. Furthermore, by a similar method, block copolymers with higher orders than styrene-ethyleneoxy group-containing (meth)acrylic acid copolymers can be obtained.

[0047] The 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. If the weight-average molecular weight (Mw) is less than 1,000, the dispersion stabilization ability for disperse dyes and pigments decreases, while if it is greater than 50,000, the ability to disperse disperse dyes and pigments decreases and the ink viscosity may become too high, which is undesirable. The weight-average molecular weight can be measured by GPC (gel permeation chromatography).

[0048] The molecular weight distribution (Mw / Mn) of the styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer obtained by polymerization is 2.0 or less, preferably 1.5 or less, and more preferably 1.4 or less. The molecular weight distribution is the value (Mw / Mn) obtained by dividing the weight average molecular weight (Mw) measured by GPC in terms of polystyrene by the number average molecular weight (Mn) measured by GPC in terms of polystyrene, and is a physical property value that serves as an index of molecular weight distribution. A smaller molecular weight distribution indicates a more uniform molecular weight, and a molecular weight distribution of 1 indicates a monomolecular weight.

[0049] The acid value of (A) styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer is preferably 50 to 300, and more preferably in the range of 100 to 250. If the acid value is less than 50, the solubility of the resin in water tends to be poor and the dispersion stabilization ability for disperse dyes and pigments tends to be poor. If the acid value exceeds 300, the affinity with aqueous media tends to be strong, and bleeding of printed images tends to occur, which is undesirable. The acid value of the resin represents the number of milligrams of KOH required to neutralize 1 g of resin, and is measured according to JIS-K 3054.

[0050] The dispersant of the present invention can be obtained by mixing component (A) with other components such as an aqueous solvent as necessary. Although not particularly limited, the dispersant of the present invention does not necessarily need to contain an acetylene-based surfactant as another component. The dispersant of the present invention can achieve the desired performance even without containing an acetylene-based surfactant.

[0051] The dispersion of the present invention contains the above-mentioned 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 pigment, and an aqueous solvent.

[0052] The constituent components of the dispersion are described below. In the dispersion of the present invention, the amount of dispersant blended is preferably 1 to 100 parts by mass, more preferably 3 to 80 parts by mass, and even more preferably 5 to 50 parts by mass, per 100 parts by mass of the disperse dye and pigment. If the amount of dispersant blended is too small, the disperse dye and pigment may not be sufficiently dispersed. On the other hand, if the amount of dispersant blended is too large, a large amount of dispersant will be present in the dispersion that is not adsorbed to the disperse dye or pigment, which is undesirable.

[0053] The disperse dye is not particularly limited and known disperse dyes can be used. Disperse dyes are classified into chemical structures such as benzene azo dyes (monoazo dyes, disazo dyes), heterocyclic azo dyes (thiazole azo dyes, benzothiazole azo dyes, pyridone azo dyes, pyrazolone azo dyes, thiophene azo dyes, etc.), anthraquinone dyes, and condensation dyes (quinophthalone, styryl dyes, coumarin dyes, etc.), and are characterized by being poorly soluble in water because they do not have a water-soluble group, and having a molecular weight of 2,000 or less, which is smaller than other dyes.

[0054] Examples of disperse dyes that can be preferably used in the present invention are shown below. CIDisperse Yellow Yellow dyes such as 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 CI 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; CIDisperse 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, red dyes such as 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; Purple dyes such as CIDisperse 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 CIDisperse Green 6:1, 9; Brown dyes such as CI Disperse Brown 1, 2, 4, 9, 13, 19, 21, 27; CIDisperse 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, 9 4, 95, 96, 102, 106, 108, 112, 113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148, 149, 153, 1 Blue dyes such as 54, 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; Black dyes such as CI Disperse Black 1, 3, 10, and 24 are preferably used.

[0055] Dyes manufactured by Nippon Kayaku Co., Ltd. include Kayaset Black KR, AN, 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, TS, Kayalon Polyester Light Blue BGL-S200, Kayalon Polyester Turq Blue GL-S200, Kayalon Polyester Blue Green FCT-S, etc. can be preferably used. Dyes manufactured by Orient Chemical Industry Co., Ltd. include 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, and Oil Blue. #15, #613, 613, N14, BOS, etc. can be preferably used. Dyes manufactured by Sumitomo Chemical Co., Ltd. include 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-GLF grain, etc. can be preferably used. As dyes manufactured by BASF, Basacryl Black X-BGW, Naozapon Black X-51, X-55, Neozapon Yellow 081, Lurafix Yellow 138, Zapon Blue 807, Neozapon Blue 807, Lurafix Blue 590, 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 Taoka Chemical 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 a dye manufactured by Bayer, Ceres Blue GN 01 or the like 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 Blue S, OA, etc. can be preferably used.

[0056] The pigment is not particularly limited, and known pigments can be used. Examples of organic pigments include azo pigments such as soluble azo pigments, insoluble azo pigments, and condensed azo pigments, quinacrylonitrile pigments, perylene pigments, perinone pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, and polycyclic pigments such as diketopyrrolopyrrole pigments, and phthalocyanine pigments. Examples of inorganic pigments include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides. Examples of carbon black include furnace black, lamp black, acetylene black, and channel black.

[0057] Specific examples of pigments include red pigments such as CI 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, and 264; Yellow pigments such as CIPigment 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 CIPigment Orange 36, 38, 43; Blue pigments such as CIPigment Blue 15, 15:2, 15:3, 15:4, 15:6, 16, 22, 60; green pigments such as CIPigment Green 7, 36, 58; Purple pigments such as CIPigment Violet 19, 23, 32, 50; Examples of black pigments include CI Pigment Black 7. Among these, CI Pigment Red 122, CI Pigment Yellow 74, 128, 155, CI Pigment Blue 15:3, 15:4, 15:6, CI Pigment Green 7, 36, CI Pigment Violet 19, CI Pigment Black 7, etc. can be preferably used.

[0058] The type, particle size, processing method, etc. of the disperse dye and / or pigment contained in the dispersion can be appropriately selected depending on the purpose. The disperse dye and pigment contained in the dispersion may be used alone or in combination of two or more types.

[0059] The concentration of the disperse dye and pigment in the dispersion is preferably 1 to 50% by mass, and more preferably 5 to 50% by mass, based on 100% by mass of the dispersion. If the concentration of the disperse dye and pigment exceeds 50% by mass, the density of the disperse dye and pigment in the dispersion increases, which may hinder their free movement and cause them to aggregate.

[0060] The aqueous solvent may be water and / or a water-soluble organic solvent, or a mixture of two or more of them may be used. It is preferable to use pure water or ion-exchanged water (deionized water) as the water. Examples of water-soluble organic solvents that can be used include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; glycols such as ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, and 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, and triethylene glycol monobutyl ether; polyhydric alcohols such as glycerin; and nitrogen-containing compounds such as N-methyl-2-pyrrolidone, 2-pyrrolidone, and 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, and more preferably 30 to 90% by mass, based on 100% by mass of the dispersion.

[0061] The method for producing the dispersion of the present invention preferably includes a step of mixing and dispersing the above-mentioned dispersant, disperse dye and / or pigment, and aqueous solvent. For example, the dispersant, disperse dye and / or pigment, and aqueous solvent can be mixed using a mixer / disperser such as a paint shaker, a bead mill, a ball mill, a dissolver, or a kneader to obtain a dispersion. When using components that are solid at room temperature, they may be mixed while heated as needed.

[0062] The static surface tension of the dispersion is preferably 60 mN / m or less, more preferably 50 mN / m or less.

[0063] The viscosity of the dispersion is preferably 50.0 mPa·s or less, more preferably 30.0 mPa·s or less. The lower limit of the viscosity of the dispersion is preferably 1.0 mPa·s or more. The viscosity in this case is measured at 25°C.

[0064] The average particle size of the disperse dye and / or pigment in the dispersion depends on the type of disperse dye and / or pigment, but is preferably 500 nm or less, more preferably 300 nm or less. The average particle size here refers to the median diameter (D50).

[0065] The dispersion of the present invention has excellent redispersibility. That is, when an ink containing a water-insoluble colorant such as a disperse dye or pigment dries, the dispersed state of the disperse dye or pigment breaks down and aggregation occurs. Generally, once aggregated, the disperse dye or pigment in the ink cannot be restored to a dispersed state even by adding a liquid medium such as water, and redispersibility is often poor. However, the dispersion of the present invention has excellent redispersibility.

[0066] The ink composition of the present invention contains the dispersion of the present invention described above, and further contains a resin and other additives as desired. (i) Dispersant (ii) Disperse dyes and / or pigments (iii) Water and / or a water-soluble organic solvent (iv) Resin (v) one or more additives selected from the group consisting of ultraviolet absorbers, antioxidants, pH adjusters, preservatives, and viscosity adjusters; It is preferred that the composition contains:

[0067] The concentration of the disperse dye and / or pigment in the ink composition is preferably 0.1 to 20% by mass, and more preferably 0.1 to 10% by mass, based on 100% by mass of the ink composition.

[0068] The proportion of water and / or the water-soluble organic solvent in the ink composition is preferably 50 to 99 mass %, and more preferably 60 to 95 mass %, based on 100 mass % of the ink composition.

[0069] 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. Furthermore, 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 a monomer or oligomer having a functional group such as an acryloyl group, a methacryloyl group, a vinyl group, or an 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, (meth)acrylates of diethylene glycol or polyethylene glycol having an ethoxy group, a propoxy group or a butoxy group, cyclohexyl(meth)acrylate, benzene In addition to monofunctional (meth)acrylates such as diethyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, hydroxyalkyl (meth)acrylate, other fluorine-containing, chlorine-containing, and silicon-containing (meth)acrylates, (meth)acrylamide, maleic acid amide, and (meth)acrylic acid, when a crosslinked structure is to be introduced, (mono, di, tri, tetra, or poly)ethylene glycol di(meth)acrylate, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, Compounds having an acrylic group or a methacrylic group, such as (meth)acrylates of 8-octanediol and 1,10-decanediol, trimethylolpropane tri(meth)acrylate, glycerin (di, tri)(meth)acrylate, di(meth)acrylate of an ethylene oxide adduct of bisphenol A or F, neopentyl glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, can be used.

[0070] The proportion of the resin in the ink composition is not particularly limited, but is preferably 0 to 30% by mass, and more preferably 0 to 20% by mass, relative to 100% by mass of the ink composition. When a resin is blended into the ink composition, it is preferably 1% by mass or more.

[0071] In addition, various additives can be contained in the ink composition. Examples of 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 can be blended separately from the disperse dye and / or pigment, water and / or water-soluble organic solvent, and resin, and make up the remainder of the dispersion and ink composition (100% by mass), specifically, 0 to 10% by mass of the ink composition (100% by mass).

[0072] The method for producing the ink composition is not particularly limited, but may include the following steps (a) and (b): (a) a step of mixing and dispersing the above-mentioned dispersant, a disperse dye and / or a pigment, and an aqueous solvent to obtain a dispersion; (b) 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; It is preferable to employ a method including the following.

[0073] The ink composition is applied to a recording medium by an ink jet recording method, a recording method using a writing instrument such as a pen, or other printing method. The ink composition of the present invention is particularly preferably used in an ink jet recording method. [Example]

[0074] (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" means "parts by mass" and "%" means "% by mass."

[0075] <Production Example 1> [Preparation of aqueous polymer solution] A three-neck flask equipped with a thermocouple, a stirrer, and a reflux condenser was charged with 18 parts of styrene (hereinafter referred to as ST), 24 parts of methyl methacrylate (hereinafter referred to as MMA), 18 parts of polyethylene glycol methacrylate (average EO addition mole number 23, "Blenmer PME-1000" manufactured by NOF Corporation, hereinafter referred to as PEG(23)MA), 30 parts of methacrylic acid (hereinafter referred to as MAA), 3.96 parts of 2-{[(2-carboxyethyl)sulfanylthiocarbonyl]sulfanyl}propanoic acid (hereinafter referred to as CTA1) as a chain transfer agent, 0.27 parts of 2,2'-azobisisobutyronitrile (hereinafter referred to as AIBN) as a polymerization initiator, and 36.27 parts of 2-propanol (hereinafter referred to as IPA) as a solvent, and the flask was then deoxidized and purged with nitrogen twice to create a nitrogen atmosphere. Stirring was then started and the mixture was heated until the internal temperature reached 80°C. Stirring was continued for 8 hours, maintaining the internal temperature at 80°C. After 8 hours, 185 parts of methanol (hereinafter referred to as MeOH) was slowly added, and the mixture was then immersed in an ice bath to stop the reaction, yielding an IPA / MeOH mixed solvent solution of unneutralized polymer (hereinafter referred to as unneutralized solution A). The polymer content of the resulting unneutralized solution A, as determined from the dry residue, was 29.1%. The weight-average molecular weight (hereinafter referred to as Mw) of the unneutralized polymer was 7,300, the number-average molecular weight (hereinafter referred to as Mn) was 5,600, and the weight-average molecular weight / number-average molecular weight (hereinafter referred to as Mw / Mn) ratio was 1.3.

[0076] The weight-average molecular weight and number-average molecular weight in the present invention are values ​​calculated in terms of standard polystyrene, obtained by drying an unneutralized polymer solution at 105°C for 3 hours, dissolving it in tetrahydrofuran so that the polymer content becomes 1%, and filtering the solution through a 0.45 µm membrane filter, using gel permeation chromatography (GPC) under the following conditions. Column: Shodex KF-802, Shodex KF806M (Showa Denko) Elution solvent: tetrahydrofuran ·Flow rate: 1.0mL / min ·Injection volume: 10μL Column temperature: 40℃ Detector: RI detector

[0077] 100 parts of the resulting unneutralized solution A were weighed into a beaker, and 8.3 parts of 25% aqueous ammonia and 100 parts of ion-exchanged water were added while stirring to neutralize the polymer. The solution was then transferred to a recovery flask. 55 parts were distilled off using a rotary evaporator, 190 parts of ion-exchanged water was added, and an additional 210 parts were distilled off under reduced pressure to remove IPA and MeOH from the solution. The pH was adjusted to 9.3 and the polymer content to 16.2% using 25% aqueous ammonia and ion-exchanged water to obtain an ammonia-neutralized styrene-methacrylic acid copolymer (aqueous solution). The polymer content was calculated using the following formula: 2 g of the unneutralized solution was weighed into a pre-weighed aluminum dish, dried in a high-temperature oven at 105 °C for 3 hours, and then the dried mass was measured. (Polymer content) = 100 × {(mass after drying) - (mass of aluminum dish)} / (weight of unneutralized solution) The pH of the ammonia-neutralized styrene-methacrylic acid copolymer (aqueous solution) at 23°C was measured using a pH Meter F-21 manufactured by Horiba Ltd.

[0078] <Manufacturing Examples 2-6, 8, 9> Production was carried out in the same manner as in Production Example 1, except that the content (charging ratio) of each component, pH, polymer content, Mw, Mn, and Mw / Mn were changed as shown in Table 1. Note that CTA2 in Table 1 is 2-cyano-2-[(dodecylsulfanylthiocarbonyl)sulfanyl]propane.

[0079] <Production Example 7> A four-neck flask was charged with 6 parts of ST, 10 parts of MAA, 0.09 parts of AIBN, 0.66 parts of CTA1, and 6.09 parts of ethyl acetate (hereinafter referred to as EtOAc). A pressure-equalizing dropping funnel was charged with 8 parts of MMA, 6 parts of PEG(23)MA, and 66 parts of IPA. The four-neck flask containing the raw materials was equipped with a thermocouple, a stirrer, a reflux condenser, and a pressure-equalizing dropping funnel containing the raw materials. The flask was then deoxygenated and purged with nitrogen twice to create a nitrogen atmosphere. The contents of the flask were heated in a water bath while stirring, and the reaction was continued for 1 hour after the internal temperature reached 80 °C. The raw materials were then added to the four-neck flask through the pressure-equalizing dropping funnel, and the reaction was continued for 8 hours. The reaction was stopped by immersing the flask in an ice bath, yielding a solution of the unneutralized polymer in an IPA / EtOAc mixed solvent (hereinafter referred to as unneutralized solution B). The polymer content was 28.0% as determined from the dry residue of the unneutralized solution B. The unneutralized polymer had Mw of 9200, Mn of 7100, and Mw / Mn of 1.3.

[0080] 100 parts of the resulting unneutralized solution B was weighed into a beaker, and then 8.3 parts of 25% aqueous ammonia and 100 parts of ion-exchanged water were added while stirring to neutralize the polymer, and the liquid was then transferred to a recovery flask. 55 parts were distilled off using a rotary evaporator, and then 190 parts of ion-exchanged water was added, and another 220 parts were distilled off under reduced pressure to remove IPA and EtOAc from the solution. The pH was adjusted to 9.3 and the polymer content to 21.6% using 25% aqueous ammonia and ion-exchanged water, yielding an ammonia-neutralized styrene-methacrylic acid copolymer block polymer (aqueous solution).

[0081] <Comparative Manufacturing Examples 1 to 5> Production was carried out in the same manner as in Production Example 1, except that the content of each component (charging ratio), pH, polymer content, Mw, Mn, and Mw / Mn were changed as shown in Table 2.

[0082] [Table 1]

[0083] [Table 2]

[0084] Details of the alphanumeric notations listed in Tables 1 and 2 are as follows: ST: Styrene PEG(23)MA: polyethylene glycol methacrylate (average EO molar number 23, NOF Corp. "Blenmar PME-1000") PEG(9)MA: polyethylene glycol methacrylate (average EO molar number 9, NOF Corp. "Blenmar PME-400") MMA: Methyl methacrylate ·MAA: methacrylic acid Chain transfer agent (1) CTA1: 2-[[(2-carboxyethyl)sulfanylthiocarbonyl]-sulfanyl]propanoic acid (CAS registration number 870451-09-5) Chain transfer agent (2) CTA2: 2-cyano-2-propyl dodecyl trithiocarbonate (CAS reg. no. 870196-83-1) Chain transfer agent (3) NDM: n-dodecyl mercaptan Chain Transfer Agent (4) 3MPA: 3-Mercaptopropionic Acid

[0085] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, parts and % represent parts by mass and % by mass, respectively.

[0086] [Example 1] 15 parts of Hostaperm Blue BT-617-D (manufactured by CLARIANT, Pigment Blue 15:4) as a blue pigment, 80.5 parts of ion-exchanged water as an aqueous solvent, 4.5 parts of the polymer of Production Example 1, 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.

[0087] [Examples 2 to 9, Comparative Examples 1 to 5] In the same manner as in Example 1, dispersions of the respective examples having the compositions shown in Tables 3 and 4 below were prepared.

[0088] For each dispersion, the static surface tension, viscosity, average particle size, and redispersibility before heating (immediately after dispersion) were measured using the following methods before heating (immediately after dispersion) and after heating at 60°C for one week. The measurements before heating (immediately after dispersion) were also performed within four hours of obtaining the dispersion. The results are shown in Tables 3 and 4.

[0089] <Surface tension> Using a DY-500 high-performance surface tensiometer (Kyowa Interface Science Co., Ltd.), the static surface tension of the dispersion was measured at 25°C before heating (immediately after dispersion) and after heating at 60°C for 1 week. The change rate (%) of static surface tension was calculated using the following formula: [(static surface tension after heating - static surface tension before heating) / static surface tension before heating] x 100 The smaller the rate of change in static surface tension, the more preferable it is, and it is preferably less than ±20%.

[0090] <Viscosity> Using a TVE-20 E-type viscometer (manufactured by Toki Sangyo Co., Ltd.), the viscosity of the dispersion was measured before heating (immediately after dispersion) and after heating at 60°C for one week (25°C). The viscosity change rate (%) was calculated using the following formula: [(viscosity after heating - viscosity before heating) / viscosity before heating] x 100 The smaller the rate of change in viscosity, the more preferable it is, and it is preferably less than ±20%.

[0091] <Average particle size> Using an ELSZ-2000 Zeta Potential, Particle Size, and Molecular Weight Measurement System (Otsuka Electronics Co., Ltd.), the average particle size (D50) of the dispersion was measured before heating (immediately after dispersion) and after heating at 60°C for one week. The rate of change in average particle size (%) was calculated using the following formula: [(average particle size after heating - average particle size before heating) / average particle size before heating] x 100 The smaller the rate of change in the average particle diameter, the more preferable it is, and it is preferably less than ±40%.

[0092] <Redispersibility (visual inspection)> Before heating (immediately after dispersion), 100 μL of the dispersion was measured with a micropipette and placed in a petri dish, and allowed to dry at room temperature (approximately 25°C) for approximately 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 evaluated. The evaluation criteria for redispersibility are shown below. (Evaluation criteria) ◎: The dried material disappeared and redispersed. ◯: Some dried matter remained, but was mostly re-dispersed. △: Most of the dried material remained, and some was re-dispersed. ×: Re-dispersion of the dried product was not confirmed.

[0093] [Table 3]

[0094] [Table 4]

Claims

1. A dispersant characterized by containing (A) a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer having a molecular weight distribution (Mw / Mn) of 2.0 or less and a weight average molecular weight of 1,000 to 50,000, and (a1) a copolymer having a styrene content of 1 to 40 mass%.

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

3. 3. The dispersant according to claim 2, wherein the monomer of component (a3) ​​comprises a radical polymerizable monomer containing at least one functional group.

4. 3. The dispersant according to claim 1, which is used for dispersing disperse dyes or pigments in aqueous solvents.

5. 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.

6. An ink composition comprising the dispersion according to claim 5.

7. 3. The method for producing a dispersant according to claim 1, comprising a step of synthesizing the component (A), a styrene-ethyleneoxy group-containing (meth)acrylic acid copolymer, by living radical polymerization.

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

9. The following steps (a) and (b) (a) 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) 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, comprising:

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