Dispersant-containing liquid and dispersion

Abstract

To provide a dispersion having excellent dispersion stability of a dispersoid and having sufficiently low viscosity, and to provide a dispersant-containing liquid which can be used suitably to prepare the dispersion.SOLUTION: The dispersion of the present invention comprises: a water-soluble polyester as a dispersant; water; and a pigment as a dispersoid. The water-soluble polyester comprises in a single molecule and as constituent monomers: a polyol component containing a plurality of hydroxyl groups and a salt of an anionic functional group; and a carboxylic acid component having a plurality of carboxyl groups and a salt of an anionic functional group. Further, the dispersion of the present invention preferably comprises a moisturizer or a surface tension modifier. The dispersion of the present invention is preferably an inkjet composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to dispersant-containing liquids and dispersions. [Background technology]

[0002] Dispersions in which dispersoids are dispersed in a dispersion medium containing water are used for various purposes. An example of such a dispersion liquid is ink in which a coloring material is dispersed in a dispersion medium containing water.

[0003] In such a dispersion, a dispersant may be added in order to improve the dispersibility of the dispersoid.

[0004] For example, a disperse dye ink for inkjet recording containing water, a water-soluble organic solvent, a disperse dye, and a water-soluble polyester having an acid value of 100 to 250 is known (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-114865 Summary of the Invention [Problem to be solved by the invention]

[0006] However, it has been difficult to obtain a dispersion having a sufficiently low viscosity while also obtaining sufficiently excellent dispersion stability of dispersoids in the dispersion. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and can be realized as the following application examples.

[0008] A dispersant-containing liquid according to an application example of the present invention includes a water-soluble polyester as a dispersant and water, The water-soluble polyester contains, as constituent monomers in a single molecule, a polyol component having multiple hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having multiple carboxyl groups and a salt of an anionic functional group.

[0009] The dispersion according to an application example of the present invention includes a water-soluble polyester as a dispersant, water, and a colorant as a dispersoid, The water-soluble polyester contains, as constituent monomers in a single molecule, a polyol component having multiple hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having multiple carboxyl groups and a salt of an anionic functional group. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a table summarizing the conditions for the water-soluble polyesters obtained in Synthesis Examples 1 to 7. [Figure 2] FIG. 2 is a table summarizing the conditions of the dispersant-containing liquids according to Examples A1 to A5 and Comparative Examples A1 and A2. [Figure 3] FIG. 3 is a table summarizing the conditions of the inkjet ink concentrates according to Examples B1 to B5 and Comparative Examples B1 and B2. [Figure 4] FIG. 4 is a table summarizing the inkjet ink conditions for Examples C1 to C5 and Comparative Examples C1 and C2. [Figure 5] FIG. 5 is a table summarizing the evaluation results for the inkjet inks according to Examples C1 to C5 and Comparative Examples C1 and C2. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described in detail below. <1> Dispersant-containing liquid First, the dispersant-containing liquid of the present invention will be described.

[0012] The dispersant-containing liquid of the present invention contains a water-soluble polyester as a dispersant and water. The water-soluble polyester contains, as constituent monomers in a single molecule, a polyol component having multiple hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having multiple carboxyl groups and a salt of an anionic functional group.

[0013] This configuration allows the water-soluble polyester used as a dispersant to have sufficiently excellent water solubility, and when a dispersion in which dispersoids are dispersed is prepared using a dispersant-containing liquid, the dispersion stability of the dispersoids can be excellent, and the viscosity of the dispersion can be sufficiently low. In particular, even when stored under harsh conditions or for long periods of time, the dispersoids are less likely to aggregate. Furthermore, even if aggregation of the dispersoids occurs, a suitable dispersion state can be restored with relatively weak stirring, etc. For these reasons, the dispersion can be suitably applied, for example, to ejection by an inkjet method.

[0014] Furthermore, when preparing a dispersion using a dispersant-containing liquid, if the dispersoid is crushed or pulverized in the dispersant-containing liquid, the dispersoid, particularly the colorant described below, becomes easily crushed or pulverized due to wetting of the dispersant-containing liquid, thereby shortening the time required to prepare the dispersion. Furthermore, when an organic colorant is used as the dispersoid in the preparation of the dispersion, the affinity and adsorption for the organic colorant do not compete with the humectant or surface tension adjuster added, and the dispersion stability of the organic colorant is not adversely affected, which is preferable.

[0015] On the other hand, if the above conditions are not met, satisfactory results will not be obtained. For example, if the polyester dispersant contained in the dispersant-containing liquid has an anionic functional group salt structure in only one of the polyol and polycarboxylic acid components as constituent monomers, the water solubility of the polyester cannot be sufficiently improved, and when a dispersion in which a dispersoid is dispersed using the dispersant-containing liquid is prepared, the dispersion stability of the dispersoid cannot be sufficiently improved. Poor dispersion stability of the dispersoid is likely to increase viscosity and cause coarsening of the dispersoid, ultimately resulting in sedimentation of the solid content, making stable droplet ejection by, for example, an inkjet method impossible. Furthermore, if the polyester dispersant contained in the dispersant-containing liquid has an anionic functional group salt structure in only one of the polyol and polycarboxylic acid components as constituent monomers, the initial viscosity of the dispersion will also be high.

[0016] <1-1>Water The dispersant-containing liquid of the present invention contains water, which mainly has the function of imparting fluidity to the dispersant-containing liquid and a dispersion prepared using the dispersant-containing liquid, and functions as a dispersion medium or a solvent. As the water, it is preferable to use ion-exchanged water, pure water, or ultrapure water.

[0017] The lower limit of the water content in the dispersant-containing liquid is not particularly limited, but is preferably 30.0 mass%, more preferably 35.0 mass%, and even more preferably 40.0 mass%. The upper limit of the water content in the dispersant-containing liquid is not particularly limited, but is preferably 93.0 mass%, more preferably 90.0 mass%, and even more preferably 87.0 mass%.

[0018] This makes it possible to more reliably adjust the viscosity of the dispersant-containing liquid to a suitable value, and also to improve the dispersion stability of the dispersoid in the dispersion prepared using the dispersant-containing liquid.

[0019] <1-2> Water-soluble polyester as a dispersant Polyester is a general term for polymeric materials that have ester bonds in their main chains, and generally contains a chemical structure formed by dehydration condensation of a polyol component that has multiple hydroxyl groups in its molecule and a polycarboxylic acid component that has multiple carboxyl groups in its molecule.

[0020] In particular, the dispersant-containing liquid of the present invention contains, as a dispersant, a water-soluble polyester containing, as constituent monomers in a single molecule, a polyol component having multiple hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having multiple carboxyl groups and a salt of an anionic functional group.

[0021] The term "water-soluble" as used herein does not strictly mean "physicochemically water-soluble," but also includes substances that dissolve or finely disperse in water.

[0022] The solubility of the water-soluble polyester in water at 20° C. is preferably 1.0 g / 100 g water or more, more preferably 2.5 g / 100 g water or more, and even more preferably 5.0 g / 100 g water or more.

[0023] Examples of the anionic functional group contained in the water-soluble polyester include a sulfone group, a carboxyl group, and a phosphate group, with the sulfone group and the carboxyl group being preferred. The water-soluble polyester preferably contains at least one of a sulfo group and a carboxyl group in both the polyol component and the polycarboxylic acid component. In other words, the water-soluble polyester preferably contains, as constituent monomers, a polyol component having at least one of a sulfonate and a carboxylate, and a polycarboxylic acid component having at least one of a sulfonate and a carboxylate.

[0024] This allows the anionic functional groups to be evenly arranged on the polyester chain, making it easier to obtain a low-viscosity dispersion, and also makes it possible to improve the ejection stability of the dispersion prepared using the dispersant-containing liquid when used in an inkjet method.

[0025] The water-soluble polyester may contain, in a single molecule, both a polyol component having a salt of an anionic functional group and a polycarboxylic acid component having a salt of an anionic functional group, and may further contain, in addition to such a constituent monomer having an anionic functional group, a constituent monomer not having an anionic functional group.

[0026] However, the lower limit of the proportion of the monomer having an anionic functional group (i.e., the sum of the proportion of the polyol component having multiple hydroxyl groups and an anionic functional group and the proportion of the polycarboxylic acid component having multiple carboxyl groups and an anionic functional group) in all the monomers constituting the water-soluble polyester is preferably 10 mol%, more preferably 15 mol%. Also, the upper limit of the proportion of the monomer having an anionic functional group (i.e., the sum of the proportion of the polyol component having multiple hydroxyl groups and an anionic functional group and the proportion of the polycarboxylic acid component having multiple carboxyl groups and an anionic functional group) in all the monomers constituting the water-soluble polyester is preferably 60 mol%.

[0027] This allows both sufficient water solubility and hydrophobic adsorption to the colorant, thereby making it possible to obtain a more stable colorant dispersion.

[0028] The water-soluble polyester may contain a monomer having an aromatic ring as a constituent monomer.

[0029] This allows the water-soluble polyester to have a sufficiently large hydrophobic adsorption force to dispersoids composed of the dispersant-containing liquid of the present invention and a highly lipophilic material such as an oil-based dye or a disperse dye, and also allows the water-soluble polyester molecules to have a more excellent flexibility and conform more favorably to the surface shape of the dispersoids. As a result, the dispersoids can be more favorably adsorbed to the water-soluble polyester, and the dispersion stability of the dispersoids in the dispersion can be further improved.

[0030] Examples of the chemical structure of the aromatic ring contained in the monomer having an aromatic ring include a phenyl group, a biphenyl group, a naphthyl group, and functional groups in which at least a portion of the hydrogen atoms of these functional groups have been substituted with other atoms or atomic groups. One or more selected from these may be used in combination.

[0031] When the water-soluble polyester contains a monomer having an aromatic ring as a constituent monomer, the monomer may have the above-mentioned anionic functional group together with the aromatic ring, or may have the aromatic ring but not the above-mentioned anionic functional group.

[0032] When the water-soluble polyester contains a monomer having an aromatic ring as a constituent monomer, the monomer may be a polyol component or a polycarboxylic acid component.

[0033] When the water-soluble polyester contains a monomer having an aromatic ring as a constituent monomer, the lower limit of the proportion of the monomer having an aromatic ring in all the monomers constituting the water-soluble polyester is preferably 40 mol%, more preferably 45 mol%, and even more preferably 50 mol%.When the water-soluble polyester contains a monomer having an aromatic ring as a constituent monomer, the upper limit of the proportion of the monomer having an aromatic ring in all the monomers constituting the water-soluble polyester is preferably 80 mol%, more preferably 75 mol%, and even more preferably 70 mol%. This makes the above-mentioned effects more pronounced.

[0034] Examples of the polyol component having an anionic functional group include a polyol component having a sulfo group, and a polyol component having a carboxyl group that does not form an ester bond in the water-soluble polyester, as shown below.

[0035] Examples of polyol components having a sulfo group include 2,3-dihydroxy-1-propanesulfonic acid, 2-[bis(2-hydroxyethyl)amino]ethanesulfonic acid, 3-[bis(2-hydroxyethyl)amino]-1-propanesulfonic acid, and 2-hydroxy-3-[bis(2-hydroxyethyl)amino]-1-propanesulfonic acid.

[0036] Examples of the polyol component having a carboxyl group that does not form an ester bond in the water-soluble polyester include dimethylolpropionic acid, dimethylolbutanoic acid, N,N-bis(2-hydroxyethyl)-β-alanine, and N,N-bis(2-hydroxyethyl)succinamic acid.

[0037] In particular, the water-soluble polyester preferably contains at least one selected from the group consisting of salts of 2-[bis(2-hydroxyethyl)amino]ethanesulfonic acid and salts of dimethylolpropionic acid as a polyol component having a salt of an anionic functional group.

[0038] This makes it possible to make the viscosity of the dispersant-containing liquid and the dispersion liquid prepared using the dispersant-containing liquid more suitable, and also makes it possible to make the dispersion stability of the dispersoid more excellent.

[0039] Examples of the polycarboxylic acid component having an anionic functional group include a polycarboxylic acid component having a sulfo group, and a polycarboxylic acid component having a carboxyl group that does not form an ester bond in the water-soluble polyester, as shown below.

[0040] Examples of polycarboxylic acid components having a sulfo group include sulfoisophthalic acid, sulfoterephthalic acid, sulfosuccinic acid, sulfomalic acid, 2,3-disulfosuccinic acid, sulfotartaric acid, sulfomalic acid, sulfomaleic acid, sulfofumaric acid, 1-sulfo-1,2-cyclohexanedicarboxylic acid, 3-(sodiooxysulfonyl)glutaric acid, dihydroxybenzenedisulfonic acid, dihydroxybenzenesulfonic acid, and dihydroxynaphthalenesulfonic acid.

[0041] Examples of the polycarboxylic acid component having a carboxyl group that does not form an ester bond in the water-soluble polyester include tricarballylic acid, β-alanine diacetic acid, trimellitic acid, trimesic acid, pyromellitic acid, and mellophanic acid.

[0042] In particular, the water-soluble polyester preferably contains at least one selected from the group consisting of salts of sulfosuccinic acid and salts of β-alanine diacetic acid as the polycarboxylic acid component having a salt of an anionic functional group.

[0043] This makes it possible to make the viscosity of the dispersant-containing liquid and the dispersion liquid prepared using the dispersant-containing liquid more suitable, and also makes it possible to make the dispersion stability of the dispersoid more excellent.

[0044] Examples of polyol components having an aromatic ring include 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzenedimethanol, biphenol, 4,4'-methylenebisphenol, 2,2-di(p-hydroxyphenyl)propane, styrene glycol, 2-phenyl-1,3-propanediol, and naphthalenediol.

[0045] Examples of polycarboxylic acid components having an aromatic ring include phthalic acid, terephthalic acid, isophthalic acid, 2,5-norbornanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 4,4'-sulfonyldibenzoic acid, 2,5-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid.

[0046] In particular, the water-soluble polyester preferably contains, as a monomer having an aromatic ring, at least one selected from the group consisting of terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 1,4-benzenedimethanol.

[0047] This makes it possible to make the viscosity of the dispersant-containing liquid and the dispersion liquid prepared using the dispersant-containing liquid more suitable, and also makes it possible to make the dispersion stability of the dispersoid more excellent.

[0048] The water-soluble polyester may contain, as a constituent monomer, a monomer that does not have the above-mentioned anionic functional group and does not have an aromatic ring. Hereinafter, such a constituent monomer will also be referred to as "other constituent monomer."

[0049] Examples of polyol components as other constituent monomers include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and 2,2'-bis(4-hydroxycyclohexyl)isopropane.

[0050] Examples of polycarboxylic acid components as other constituent monomers include oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.

[0051] In particular, the water-soluble polyester preferably contains, as another constituent monomer, at least one selected from the group consisting of adipic acid, 1,2-cyclohexanedicarboxylic acid, diethylene glycol, ethylene glycol, and 1,2-cyclohexanedimethanol.

[0052] This makes it possible to make the viscosity of the dispersant-containing liquid and the dispersion liquid prepared using the dispersant-containing liquid more suitable, and also makes it possible to make the dispersion stability of the dispersoid more excellent.

[0053] When the water-soluble polyester contains other constituent monomers as constituent monomers, the lower limit of the proportion of the other constituent monomers in all the monomers constituting the water-soluble polyester is preferably 2 mol%, more preferably 5 mol%, and even more preferably 7 mol%. When the water-soluble polyester contains other constituent monomers as constituent monomers, the upper limit of the proportion of the other constituent monomers in all the monomers constituting the water-soluble polyester is preferably 40 mol%, more preferably 35 mol%, and even more preferably 30 mol%.

[0054] In particular, the water-soluble polyester preferably contains, as the polyol component having a salt of an anionic functional group, at least one selected from the group consisting of salts of 2-[bis(2-hydroxyethyl)amino]ethanesulfonic acid and salts of dimethylolpropionic acid; as the polycarboxylic acid component having a salt of an anionic functional group, at least one selected from the group consisting of salts of sulfosuccinic acid and salts of β-alaninediacetic acid; as the aromatic ring-containing monomer, at least one selected from the group consisting of terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 1,4-benzenedimethanol; and further, as the other monomer (i.e., other constituent monomer), at least one selected from the group consisting of adipic acid, 1,2-cyclohexanedicarboxylic acid, diethylene glycol, ethylene glycol, and 1,2-cyclohexanedimethanol.

[0055] This allows the effects of including the specific constituent monomers described above to act synergistically, making it possible to further improve the viscosity of the dispersant-containing liquid or the dispersion prepared using the dispersant-containing liquid, and to further improve the dispersion stability of the dispersoid.

[0056] In the water-soluble polyester, at least a part of the anionic functional groups is in a salt structure. A basic substance may be used to form a salt of an anionic functional group.

[0057] Examples of basic substances include monovalent inorganic bases, divalent inorganic bases, and water-soluble organic amines, and one or more selected from these may be used in combination.

[0058] Examples of the monovalent inorganic base include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and ammonia, with alkali metal hydroxides being particularly preferred, and sodium hydroxide being more preferred. Examples of divalent inorganic bases include hydroxides of alkaline earth metals.

[0059] Examples of water-soluble organic amines include ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, propylamine, dipropylamine, tripropylamine, propanolamine, dipropanolamine, tripropanolamine, 2-propylaminoethanol, 2-butylaminoethanol, 3-propylamino-1-propanol, 3-butylamino-1-propanol, 1-propoxymethaneamine, 1-butoxymethaneamine, 2-propoxyethanamine, 2-butoxyethanamine, 3-propoxypropylamine, 3-butoxypropylamine, 1-amino-2-pentanol, and the like.

[0060] The lower limit of the average molecular weight of the water-soluble polyester determined by size exclusion chromatography is preferably 3,000, more preferably 5,000, and even more preferably 70,000. The upper limit of the average molecular weight of the water-soluble polyester determined by size exclusion chromatography is preferably 30,000, more preferably 25,000, and even more preferably 20,000.

[0061] This makes it possible to improve the water solubility of the water-soluble polyester used as a dispersant, and to improve the dispersion stability of the dispersoid when a dispersion in which the dispersoid is dispersed is prepared using a dispersant-containing liquid. Furthermore, the viscosity of the dispersant-containing liquid or a dispersion prepared using the dispersant-containing liquid can be adjusted to a more suitable range, and, for example, when the dispersion is an inkjet composition, the ejection stability of the inkjet composition when used in an inkjet method can be improved, and the color development of a recording portion formed using the inkjet composition can be improved.

[0062] The average molecular weight of the water-soluble polyester can be determined by measurement in accordance with JIS K7252-1:2016.

[0063] The lower limit of the acid value of the water-soluble polyester is preferably 20 mgKOH / g, more preferably 25 mgKOH / g, and even more preferably 30 mgKOH / g, and the upper limit of the acid value of the water-soluble polyester is preferably 400 mgKOH / g, more preferably 350 mgKOH / g, and even more preferably 300 mgKOH / g.

[0064] This makes it possible to improve the water solubility of the water-soluble polyester used as a dispersant, and to improve the dispersion stability of the dispersoid when a dispersion in which the dispersoid is dispersed is prepared using a dispersant-containing liquid. Furthermore, the viscosity of the dispersant-containing liquid or a dispersion prepared using the dispersant-containing liquid can be adjusted to a more suitable range, and, for example, when the dispersion is an inkjet composition, the ejection stability of the inkjet composition when used in an inkjet method can be improved, and the color development of a recording portion formed using the inkjet composition can be improved.

[0065] The acid value of the water-soluble polyester can be determined by measurement in accordance with JIS K0070:1992.

[0066] The lower limit of the content of the water-soluble polyester in the dispersant-containing liquid is preferably 3.0% by mass, more preferably 4.0% by mass, and even more preferably 4.5% by mass, and the upper limit of the content of the water-soluble polyester in the dispersant-containing liquid is preferably 35.0% by mass, more preferably 30.0% by mass, and even more preferably 28.0% by mass.

[0067] This makes it easier to adjust the viscosity of the dispersant-containing liquid or the dispersion prepared using the dispersant-containing liquid to a suitable range, making the dispersant-containing liquid or dispersion easier to handle, and also makes it possible to improve the dispersion stability of the dispersoid when a dispersion in which the dispersoid is dispersed is prepared using the dispersant-containing liquid.

[0068] The method of condensation polymerization for synthesizing the water-soluble polyester is not particularly limited, and examples thereof include melt condensation polymerization, solution condensation polymerization, and solid phase condensation polymerization.

[0069] <1-3> Basic substances The dispersant-containing liquid of the present invention may further contain a basic substance in addition to the above-mentioned components.

[0070] This allows the pH range of the dispersant-containing liquid to be adjusted to a suitable weakly basic range, ensuring a more suitable dissolution state of the water-soluble polyester in the dispersant-containing liquid, and more effectively preventing problems such as aggregation and precipitation due to insolubilization of the water-soluble polyester. As a result, for example, when a dispersion in which a dispersoid is dispersed is prepared using the dispersant-containing liquid, the dispersion stability of the dispersoid can be improved. Furthermore, when the dispersion is an inkjet composition, the ejection stability of the inkjet composition when used in an inkjet method can be improved.

[0071] When the dispersant-containing liquid of the present invention contains a basic substance, the basic substance may be, for example, the unreacted component of the substance used to form the salt of the anionic functional group described above.

[0072] Examples of basic substances include monovalent inorganic bases, divalent inorganic bases, and water-soluble organic amines, and one or more selected from these may be used in combination.

[0073] Examples of the monovalent inorganic base include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and ammonia, with alkali metal hydroxides being particularly preferred, and sodium hydroxide being more preferred. Examples of divalent inorganic bases include hydroxides of alkaline earth metals.

[0074] The water-soluble organic amine may be, for example, an organic amine having a solubility in water of 10 g / 100 g water or more at 20° C. Specific examples of the water-soluble organic amine include alkylamines such as monoethylamine, diethylamine, triethylamine, monomethylamine, dimethylamine, and trimethylamine, diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, butyldiethanolamine, ethyldiethanolamine, and 2-amino-2-ethyl-1,3-propanediol.

[0075] <1-4> Other ingredients The dispersant-containing liquid of the present invention may further contain components other than the components described above. Hereinafter, such components will be referred to as "other components" in this section.

[0076] Examples of other components include dispersants and resin components other than the water-soluble polyester, moisturizers, surface tension adjusters, preservatives, chelating agents, etc., and one or more selected from these can be used in combination.

[0077] However, the dispersant-containing liquid of the present invention does not contain dispersoid. The dispersion of the present invention, which will be described later, contains dispersoid in addition to the components of the dispersant-containing liquid of the present invention described above.

[0078] The content of other components in the dispersant-containing liquid of the present invention is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less.

[0079] <1-6>Other The dispersant-containing liquid of the present invention preferably satisfies the following conditions.

[0080] For example, the lower limit of the pH of the dispersant-containing liquid of the present invention at 20°C is preferably 7.0, more preferably 7.2, and even more preferably 7.4. The upper limit of the pH of the dispersant-containing liquid of the present invention at 20°C is preferably 10.0, more preferably 9.0, and even more preferably 8.6.

[0081] This ensures a more suitable dissolved state of the water-soluble polyester, and more effectively prevents problems such as aggregation and precipitation due to insolubilization of the water-soluble polyester. As a result, for example, when a dispersion in which a dispersoid is dispersed is prepared using a dispersant-containing liquid, the dispersion stability of the dispersoid can be improved. Furthermore, when the dispersion is a composition for inkjet, the ejection stability of the composition for inkjet by an inkjet method can be improved.

[0082] The dispersant-containing liquid of the present invention can be suitably prepared, for example, by adding necessary components such as water to the water-soluble polyester obtained by the condensation reaction and stirring the mixture. If necessary, heating may be performed during stirring.

[0083] <2> dispersion liquid Next, the dispersion of the present invention will be described.

[0084] The dispersion of the present invention contains a water-soluble polyester as a dispersant, water, and a colorant as a dispersoid. The water-soluble polyester contains, as constituent monomers in a single molecule, a polyol component having multiple hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having multiple carboxyl groups and a salt of an anionic functional group.

[0085] This configuration allows the water-soluble polyester used as a dispersant to have sufficiently excellent water solubility, excellent dispersion stability of the dispersoid in the dispersion, and a sufficiently low viscosity of the dispersion. In particular, dispersoid aggregation is unlikely to occur even when stored under harsh conditions or for long periods of time. Even if dispersoid aggregation does occur, a favorable dispersion state can be restored with relatively weak stirring, etc. For these reasons, the dispersion can be suitably applied to, for example, ejection by an inkjet method.

[0086] <2-1>Water The dispersion of the present invention contains water, which mainly has the function of imparting fluidity to the dispersion and functions as a dispersion medium or a solvent. As the water, it is preferable to use ion-exchanged water, pure water, or ultrapure water.

[0087] The lower limit of the water content in the dispersion is not particularly limited, but is preferably 35.0 mass%, more preferably 40.0 mass%, and even more preferably 45.0 mass%. The upper limit of the water content in the dispersant-containing liquid is not particularly limited, but is preferably 93.0 mass%, more preferably 90.0 mass%, and even more preferably 87.0 mass%.

[0088] This makes it possible to more reliably adjust the viscosity of the dispersion to a suitable value, and also to improve the dispersion stability of the dispersoid in the dispersion.

[0089] <2-2> Water-soluble polyester as a dispersant The dispersion of the present invention contains, as a dispersant, a water-soluble polyester containing, as constituent monomers in a single molecule, a polyol component having multiple hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having multiple carboxyl groups and a salt of an anionic functional group.

[0090] Such a water-soluble polyester preferably satisfies the same conditions as those explained in the above item <1-2>. This provides the same effect as described above.

[0091] The lower limit of the content of the water-soluble polyester in the dispersion is preferably 0.3 mass%, more preferably 0.4 mass%, and even more preferably 0.5 mass%, and the upper limit of the content of the water-soluble polyester in the dispersion is preferably 17.5 mass%, more preferably 15.0 mass%, and even more preferably 14.0 mass%.

[0092] This makes it easier to adjust the viscosity of the dispersion to a more suitable range, making the dispersion easier to handle and improving the dispersion stability of the dispersoid.

[0093] The lower limit of the content of the water-soluble polyester relative to 100.0 parts by mass of dispersoid contained in the dispersion is preferably 10.0 parts by mass, more preferably 15.0 parts by mass, and even more preferably 20.0 parts by mass, and the upper limit of the content of the water-soluble polyester relative to 100.0 parts by mass of dispersoid contained in the dispersion is preferably 200.0 parts by mass, more preferably 150.0 parts by mass, and even more preferably 90.0 parts by mass.

[0094] This makes it easier to adjust the viscosity of the dispersion within a suitable range, making the dispersion easier to handle and improving the dispersion stability of the dispersoid.

[0095] <2-3>Dispersion The dispersion of the present invention comprises a dispersoid.

[0096] The dispersoid may be any dispersoid contained in the dispersion in a dispersed state, and may be made of various materials depending on the intended use of the dispersion. Examples of dispersoid constituent materials include resin materials that are poorly soluble in water, and coloring materials such as various pigments, disperse dyes, sublimation dyes, oil-soluble dyes, and other dyes.

[0097] Examples of pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, azo pigments, and carbon black.

[0098] More specifically, examples of yellow pigments include CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 14C, 16, 17, 24, 34, 35, 37, 42, 53, 55, 65, 73, 74, 75, 81, 83, 93, 95, 97, 98, 100, 101, 104, 108, 109, 110, 114, 117, 120, 128, 129, 138, 150, 151, 153, 154, and 180. Examples of magenta pigments include CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 48(Ca), 48(Mn), 48:2, 48:3, 48:4, 49, 49:1, 50, 51, 52, 52:2, 53, 53:1, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 7(Ca), 57:1, 60, 60:1, 63:1, 63:2, 64, 64:1, 81, 83, 87, 88, 89, 90, 101, 104, 105, 106, 108, 112, 114, 122, 123, 146, 149, 163, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 209, and 219. Examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:34, 16, 17:1, 22, 25, 56, 60, and CI Vat Blue 4, 60, and 63. Other color pigments include, for example, CI Pigment Orange 5, 13, 16, 17, 36, 43, and 51; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, and 36; and CI Pigment Violet 1, 3, 5:1, 16, 19, 23, and 38.

[0099] Examples of disperse dyes include CI Disperse Red 60, 82, 86, 86:1, 167:1, 279, and 364; CI Disperse Yellow 54, 64, 71, 86, 114, 153, 232, 233, and 245; CI Disperse Blue 27, 60, 73, 77, 77:1, 87, 257, 359, and 367; CI Disperse Violet 26, 33, 36, and 57; and CI Disperse Orange 30, 41, and 61.

[0100] Examples of solvent dyes include CI Solvent Yellow 16, 21, 25, 29, 33, 51, 56, 82, 88, 89, 150, and 163, CI Solvent Red 7, 8, 18, 24, 27, 49, 109, 122, 125, 127, 130, 132, 135, 218, 225, and 230, CI Solvent Blue 14, 25, 35, 38, 48, 67, 68, 70, and 132, and CI Solvent Black 3, 5, 7, 27, 28, 29, and 34.

[0101] The dispersoid contained in the dispersion of the present invention is preferably an organic colorant, and more preferably at least one selected from the group consisting of pigments, disperse dyes, and oil-soluble dyes.

[0102] This can improve the dispersion stability of the dispersoid in the dispersion. Furthermore, the dispersion of the present invention can be suitably applied to, for example, an ink composition, particularly an inkjet composition, and can improve the color development properties of the recording portion formed using the composition.

[0103] The content of the dispersoid in the dispersion of the present invention is not particularly limited, but the lower limit of the content of the dispersoid in the dispersion of the present invention is preferably 1.0 mass%, more preferably 2.0 mass%, and even more preferably 3.0 mass%, and the upper limit of the content of the dispersoid in the dispersion of the present invention is preferably 40.0 mass%, more preferably 35.0 mass%, and even more preferably 30.0 mass%.

[0104] This allows the dispersion to have a sufficiently high dispersoid content while improving the dispersion stability of the dispersoid. Furthermore, when the dispersoid is dispersed using a dispersing machine such as a bead mill, the viscosity of the resulting dispersion can be more easily adjusted to a more suitable range. Furthermore, when the dispersion is an ink composition such as an inkjet composition, the color development of the recording portion formed using the ink composition can be improved.

[0105] <2-4> Basic substances The dispersion of the present invention may further contain a basic substance in addition to the above-mentioned components.

[0106] This makes it possible to adjust the pH range of the dispersion to a suitable range, ensure a more suitable dissolution state of the water-soluble polyester in the dispersion, and more effectively prevent problems such as aggregation and precipitation due to insolubilization of the water-soluble polyester. As a result, for example, the dispersion stability of the dispersoid in the dispersion can be improved. Furthermore, when the dispersion is a composition for inkjet, the ejection stability of the composition for inkjet by the inkjet method can be improved.

[0107] Such a basic substance preferably satisfies the same conditions as those explained in <1-3> above. This provides the same effect as described above.

[0108] <2-5> Moisturizer The dispersion of the present invention may also contain a humectant.

[0109] This makes it possible to more effectively avoid clogging of the inkjet head due to drying when the dispersion prepared using the dispersant-containing liquid is ejected by an inkjet method, thereby improving the ejection stability of the dispersion.

[0110] Examples of moisturizing agents include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, propylene glycol, dipropylene glycol, tripropylene glycol, isobutylene glycol, glycerin, diglycerin, mesoerythritol, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipentaerythritol. monosaccharides, disaccharides, oligosaccharides, and polysaccharides such as glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose, and derivatives of these sugars; betaines of glycine and trimethylglycine; urea derivatives such as urea, thiourea, ethyleneurea, and 1,3-dimethylimidazolidinones; and lactams such as 2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, and ε-caprolactam.

[0111] The content of the humectant in the dispersion of the present invention is not particularly limited, but the lower limit of the content of the humectant in the dispersion of the present invention is preferably 3.0 mass%, more preferably 5.0 mass%, and even more preferably 7.0 mass%, and the upper limit of the content of the humectant in the dispersion of the present invention is preferably 40.0 mass%, more preferably 35.0 mass%, and even more preferably 30.0 mass%.

[0112] <2-6> Surface tension adjuster The dispersion of the present invention may contain a surface tension modifier.

[0113] This allows ink droplets to be formed more stably when the dispersion is ejected by an inkjet method, and allows the dot size to be more uniform.

[0114] Examples of the surface tension adjuster include surfactants and water-soluble solvents that lower the surface tension when dissolved.

[0115] Examples of surfactants include cationic surfactants, anionic surfactants, and nonionic surfactants. In order to suppress the effect of anionic surfactants on the solubility of the water-soluble polyester, nonionic surfactants are particularly preferred.

[0116] Examples of nonionic non-reactive surfactants include silicone surfactants, fluorine surfactants, and acetylene glycol surfactants.

[0117] Examples of silicone surfactants include BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-349, and BYK-3455 manufactured by BYK Japan; Silface SAG503A, SAG002, SAG005, and SAG014 manufactured by Nissin Chemical Industry Co., Ltd.; and KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, and KF-6012 manufactured by Shin-Etsu Chemical Co., Ltd.

[0118] Examples of fluorine-based surfactants include FC-4430 and FC-4432 manufactured by 3M Japan, Megafac F-444, F-477, F-553 and F-556 manufactured by DIC Corporation, and Surflon S-241, S-242, S-243 and S-386 manufactured by AGC Seimi Chemical Co., Ltd.

[0119] Examples of acetylene glycol surfactants include Surfynol 82, 465, 485, 2502, Olfine E1010, E1020, PD-002W, PD-004, EXP4001, EXP4002, EXP4123, and EXP4300, manufactured by Nissin Chemical Industry Co., Ltd.; and Acetylenol E00, E103T, E40, E60, E100, and E200, manufactured by Kawaken Fine Chemicals Co., Ltd. ("Surfynol" and "Olfine" are registered trademarks).

[0120] Examples of the water-soluble solvent include lower alcohols such as 2-propanol, 1-propanol, 2-butanol, and 1-butanol; glycol monoethers such as diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, ethylene glycol mono-2-ethylhexyl ether, and diethylene glycol mono-2-ethylhexyl; lower alkyl 1,2-diols such as 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol; and glycerin monoethers such as glycerin monobutyl ether and glycerin-2-ethylhexyl ether.

[0121] The content of the surface tension modifier in the dispersion of the present invention is not particularly limited, but the lower limit of the content of the surface tension modifier in the dispersion of the present invention is preferably 0.1 mass%, more preferably 0.3 mass%, and even more preferably 1.0 mass%, and the upper limit of the content of the surface tension modifier in the dispersion of the present invention is preferably 10.0 mass%, more preferably 8.0 mass%, and even more preferably 6.0 mass%.

[0122] <2-7> Other ingredients The dispersion of the present invention may further contain components other than those described above. Hereinafter, such components will be referred to as "other components" in this section.

[0123] Examples of other components include dispersants other than the water-soluble polyester, resin components, preservatives, chelating agents, etc., and one or more selected from these may be used in combination.

[0124] By including a preservative, for example, spoilage of the dispersion liquid by microorganisms can be prevented, and precipitation and aggregation of solids in the dispersion liquid can be more effectively prevented.

[0125] Examples of preservatives include methylisothiazolinone, chloromethylisothiazolinone, octylisothiazolinone, dichlorooctylisothiazolinone, benzisothiazolinone, dicyclohexylamine, iodopropynyl butylcarbamate, and diethylene oximide.

[0126] By including a chelating agent, for example, polyvalent cations in the dispersion can be trapped, and precipitation and aggregation of solids in the dispersion can be more effectively prevented.

[0127] Examples of the chelating agent include ethylenediaminetetratetraacetate, diethyltriaminepentaacetate, pentetate, iminodisuccinate, and aspartic acid diacetate.

[0128] However, the content of other components in the dispersion of the present invention is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less.

[0129] <2-9>Other The dispersion of the present invention preferably satisfies the following conditions.

[0130] For example, the lower limit of the pH of the dispersion of the present invention at 20°C is preferably 7.0, more preferably 7.2, and even more preferably 7.4, while the upper limit of the pH of the dispersion of the present invention at 20°C is preferably 10.0, more preferably 9.0, and even more preferably 8.6.

[0131] This ensures a more suitable dissolved state of the water-soluble polyester, and more effectively prevents, for example, problems such as aggregation and precipitation due to insolubilization of the water-soluble polyester. As a result, for example, the dispersion stability of the dispersoid in the dispersion can be improved. Furthermore, when the dispersion is a composition for inkjet, the ejection stability of the composition for inkjet by the inkjet method can be improved.

[0132] The dispersion of the present invention may be used for any purpose, such as paints and various ink compositions, but is preferably used as an inkjet composition.

[0133] In inkjet compositions, the sedimentation or aggregation of dispersoids in the composition, or the precipitation of solids in the inkjet head or flow channel, can have a significant impact on the ejection stability when used by the inkjet method, and in some cases, may even make it impossible to eject the composition by the inkjet method. In other words, inkjet compositions are required to have an appropriate viscosity and a higher level of dispersion stability of the dispersoids. In contrast, in the present invention, an inkjet composition as a dispersion can be made to have an appropriate viscosity and a higher level of dispersion stability of the dispersoids. In other words, when the dispersion is an inkjet composition, the effects of the present invention are more pronounced. In this specification, the term "inkjet composition" is used to conceptually include not only the inkjet ink itself that is ejected by the inkjet method, but also, for example, a stock solution of inkjet ink that is mixed with other components and used to prepare an inkjet.

[0134] The lower limit of the viscosity of the dispersion of the present invention at 20°C is not particularly limited, but is preferably 0.5 mPa·s, more preferably 3 mPa·s.The upper limit of the viscosity of the dispersion of the present invention at 20°C is not particularly limited, but is preferably 10 mPa·s, more preferably 6 mPa·s, and even more preferably 4.5 mPa·s.

[0135] If the viscosity is sufficiently low in this way, for example, when the dispersion of the present invention is a composition for inkjet, the ejection stability can be made more excellent.

[0136] The viscosity is measured at 20°C using a viscoelasticity tester such as MCR-102 manufactured by Pysica, with a shear rate of 200 [s -1 The viscosity can be measured by reading the viscosity at this point.

[0137] The lower limit of the surface tension of the dispersion of the present invention at 20° C. is not particularly limited, but is preferably 20 mN / m, more preferably 21 mN / m, and even more preferably 23 mN / m. The upper limit of the surface tension of the dispersion of the present invention at 20° C. is not particularly limited, but is preferably 50 mN / m, and more preferably 40 mN / m.

[0138] As a result, for example, when the dispersion of the present invention is an inkjet composition, clogging of the nozzle of a recording device when using an inkjet method is less likely to occur, and the ejection stability of the dispersion of the present invention is further improved. Furthermore, even if clogging of the nozzle occurs, the nozzle can be capped, i.e., recovery by capping can be more excellent.

[0139] The surface tension can be measured by the Wilhelmy method using a surface tensiometer such as the CBVP-7 manufactured by Kyowa Interface Science Co., Ltd.

[0140] When the dispersion of the present invention is an inkjet ink, the ink is usually applied to a recording device using an inkjet method in a state where it is contained in a container such as a cartridge, a bag, a tank, etc. In other words, the recording device of the present invention is equipped with a container such as an ink cartridge that contains the inkjet ink as the dispersion of the present invention.

[0141] The dispersion of the present invention can be prepared, for example, by mixing the above-described dispersant-containing liquid of the present invention with a substance to be a dispersoid.

[0142] In preparing the dispersion of the present invention, a dispersing device such as a ball mill, a sand mill, a roll mill, a jet mill, a high-pressure homogenizer, etc. Examples of commercially available dispersing devices include a Super Mill, a Sand Grinder, a Bead Mill, an Agitator Mill, a Grain Mill, a Dyno Mill, a Pearl Mill, and a Cobol Mill (all trade names).

[0143] When preparing the dispersion of the present invention, in addition to the dispersant-containing liquid of the present invention and the substance to be the dispersoid, components such as water, a basic substance, a humectant, and a surface tension adjuster may be used. During preparation of the dispersion of the present invention, heating may be carried out as necessary.

[0144] Furthermore, the dispersion of the present invention is not limited to those prepared by the above-mentioned method. For example, the dispersion of the present invention may be prepared by mixing the water-soluble polyester obtained by the condensation reaction, the substance to be dispersed, water, and other necessary components all at once, or by adding and mixing them sequentially in a predetermined order, without using the dispersant-containing liquid of the present invention.

[0145] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these. [Example]

[0146] Next, specific examples of the present invention will be described. <3> Synthesis of water-soluble polyester (Synthesis Example 1) A mixture of 3.2 parts by weight of sodium 2-[bis(2-hydroxyethyl)amino]ethanesulfonate, 3.5 parts by weight of sodium sulfosuccinate, 18.4 parts by weight of terephthalic acid, 18.4 parts by weight of isophthalic acid, 44.1 parts by weight of 1,4-benzenedimethanol, 5.2 parts by weight of adipic acid, 7.2 parts by weight of diethylene glycol, and 0.05 parts by weight of antimony trioxide (catalyst) was mixed and heated in a nitrogen atmosphere at 160°C for 1 hour, then heated to 230°C over 3 hours. The reaction was continued for 3 hours while distilling off water under reduced pressure at 230°C, and then cooled to room temperature to obtain a water-soluble polyester having a salt of an anionic functional group. The resulting water-soluble polyester had an average molecular weight of 12,000 and an acid value of 50 KOHmg / g as determined by size exclusion chromatography. The average molecular weight of the water-soluble polyester was determined by measurement in accordance with JIS K7252-1:2016, and the acid value of the water-soluble polyester was determined by measurement in accordance with JIS K0070:1992.

[0147] (Synthesis Examples 2 to 7) A water-soluble polyester was obtained in the same manner as in Synthesis Example 1, except that the types and amounts of raw material monomers used in the synthesis of the water-soluble polyester were changed as shown in FIG.

[0148] The conditions for the water-soluble polyesters obtained in Synthesis Examples 1 to 7 are summarized in Figure 1. Regarding the numerical values ​​for "components used in synthesis" in Figure 1, the upper row indicates the amount of each component used in parts by mass, and the lower row indicates the amount of each component used in mol%. In Figure 1, sodium 2-[bis(2-hydroxyethyl)amino]ethanesulfonate is indicated as "BES," dimethylolpropionic acid as "DMPA," sodium sulfosuccinate as "SSA," sodium β-alaninediacetate as "βADA," sodium 5-sulfoisophthalate as "SIPA," terephthalic acid as "TPA," isophthalic acid as "IPA," 2,6-naphthalenedicarboxylic acid as "NDA," 1,4-benzenedimethanol as "BDM," adipic acid as "AA," 1,2-cyclohexanedicarboxylic acid as "12CHA," 1,4-cyclohexanedicarboxylic acid as "14CHA," succinic acid as "SA," diethylene glycol as "DEG," ethylene glycol as "EG," 1,2-cyclohexanedimethanol as "12CHM," and 1,4-cyclohexanedimethanol as "14CHM."

[0149] <4> Preparation of dispersant-containing liquid (Example A1) 25 parts by mass of the water-soluble polyester synthesized in Synthesis Example 1 and 75 parts by mass of pure water were mixed and stirred at 70° C. for 60 minutes to obtain 100 parts by mass of a uniform dispersant-containing liquid.

[0150] (Examples A2 to A5) A dispersant-containing liquid was prepared in the same manner as in Example A1, except that the types and amounts of the components used in preparing the dispersant-containing liquid were changed as shown in FIG.

[0151] (Comparative examples A1 and A2) A dispersant-containing liquid was prepared in the same manner as in Example A1, except that the types and amounts of the components used in preparing the dispersant-containing liquid were changed as shown in FIG.

[0152] The conditions for the dispersant-containing liquids according to the above-mentioned respective Examples and Comparative Examples are summarized in Figure 2. The numerical values ​​for "amount used" of "components used in preparation" in Figure 2 indicate the amount of each component used in parts by mass.

[0153] <5> Preparation of inkjet ink stock solutions as dispersions Example B1 50 parts by mass of the dispersant-containing liquid prepared in Example A1 and 30 parts by mass of pure water were mixed, to which 20 parts by mass of an organic pigment, CI Pigment Blue 15:3, was added as a colorant. The mixture was then dispersed in a bead mill using 0.5 mm diameter zirconia balls until the particle size reached 130 nm, the beads were separated, and the mixture was filtered through a filter with a pore size of 8 μm to obtain a stock solution of inkjet ink as a dispersion.

[0154] (Examples B2 to B5) A stock solution of inkjet ink as a dispersion was prepared in the same manner as in Example B1, except that the type of dispersant-containing liquid and the type of colorant used in preparing the stock solution of inkjet ink were changed as shown in FIG. 3.

[0155] (Comparative examples B1 and B2) A stock solution of inkjet ink as a dispersion was prepared in the same manner as in Example B1, except that the type of dispersant-containing liquid and the type of colorant used in preparing the stock solution of inkjet ink were changed as shown in FIG. 3.

[0156] The conditions for the inkjet ink stock solutions according to the examples and comparative examples are summarized in Figure 3. The numerical values ​​for "Amounts Used" under "Components Used in Preparation" in Figure 3 indicate the amounts of each component used in parts by mass. The pH values ​​at 20°C of the inkjet ink stock solutions according to the examples were all within the range of 7.0 to 10.0.

[0157] <6> Preparation of inkjet inks as dispersions Example C1 20.0 parts by mass of the inkjet ink stock solution prepared in Example B1 above, 15 parts by mass of glycerin and 10.0 parts by mass of triethylene glycol as humectants, 0.2 parts by mass of Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) and 0.6 parts by mass of BYK-348 (manufactured by BYK Japan KK) as surface tension adjusters, 4.0 parts by mass of 1,2-hexanediol, 0.2 parts by mass of triethanolamine as a pH adjuster, and 50.0 parts by mass of pure water were mixed, stirred at room temperature for 1 hour, and filtered through a microfiltration filter with a pore size of 3 μm to obtain an inkjet ink dispersion.

[0158] (Examples C2 to C5) Inkjet inks as dispersions were prepared in the same manner as in Example C1, except that the type of inkjet ink stock solution used to prepare the inkjet ink, the type and amount of each added component were changed as shown in FIG. 4.

[0159] (Comparative examples C1 and C2) Inkjet inks as dispersions were prepared in the same manner as in Example C1, except that the type of inkjet ink stock solution used to prepare the inkjet ink, the type and amount of each added component were changed as shown in FIG. 4.

[0160] The conditions for the inkjet inks according to the examples and comparative examples are summarized in Figure 4. The numerical values ​​for "Amounts Used" under "Components Used in Preparation" in Figure 4 indicate the amounts of each component used in parts by mass. In Figure 4, triethylene glycol monobutyl ether is indicated as "TEGBE." The inkjet inks according to the examples all had a pH value at 20°C ranging from 7.0 to 10.0. The inkjet inks according to the examples all had a surface tension value ranging from 23 mN / m to 30 mN / m. The surface tension was measured by the Wilhelmy method at 20°C using a surface tensiometer (CBVP-7, manufactured by Kyowa Interface Science Co., Ltd.).

[0161] <7> evaluation <7-1>Initial viscosity The inkjet inks of Examples C1 to C5 and Comparative Examples C1 and C2 were each measured at a shear rate of 200 [s] at 20°C using a viscoelasticity tester MCR-102 (manufactured by Pysica). -1 The viscosity at this point was read to determine the initial viscosity, which was then evaluated according to the following criteria.

[0162] A: The initial viscosity is less than 4.6 mPa·s. B: The initial viscosity is 4.6 mPa·s or more and less than 6.0 mPa·s. C: The initial viscosity is 6.0 mPa·s or more and less than 12.0 mPa·s. D: The initial viscosity is 12.0 mPa·s or more.

[0163] <7-2> Evaluation of storage stability based on viscosity stability The inkjet inks of Examples C1 to C5 and Comparative Examples C1 and C2 were each placed in a sample container and left to stand at 70°C for one week, after which the viscosity at 20°C was measured and compared with the viscosity at 20°C of the inkjet ink immediately after production, and evaluated according to the following criteria. The smaller the rate of change in viscosity, the better the dispersion stability of the dispersoid.

[0164] A: Viscosity fluctuation rate is less than 10% immediately after production. B: The viscosity fluctuation rate from immediately after production is 10% or more but less than 20%. C: Viscosity fluctuation rate from immediately after production is 20% or more. D: Aggregation and gelation occurred, making it impossible to measure viscosity.

[0165] <7-3> Evaluation of storage stability based on particle size stability The inkjet inks of Examples C1 to C5 and Comparative Examples C1 and C2 were placed in a sample container and left at 70°C for one week. The average particle size of the dispersoids contained in the inkjet ink was then determined in an environment of 20°C, and compared with the average particle size of the dispersoids contained in the inkjet ink immediately after production, and evaluated according to the following criteria. The smaller the rate of variation in the particle size of the dispersoid, the better the dispersion stability of the dispersoid. In this specification, the average particle size refers to the average particle size on a volume basis, unless otherwise specified. The average particle size was determined by measurement using a Microtrac UPA (manufactured by Nikkiso Co., Ltd.).

[0166] A: The rate of change in the average particle size of the dispersoids immediately after production is less than 15%. B: The rate of change in the average particle size of the dispersoids immediately after production is 15% or more and less than 30%. C: The rate of change in the average particle size of the dispersoids immediately after production is 30% or more. D: Aggregation and gelation occurred, making it impossible to measure the particle size of the dispersed matter. The above evaluation results are summarized in Figure 5.

[0167] As is clear from Figure 5, the inkjet ink of the present invention had excellent dispersion stability of the dispersoid and a sufficiently low initial viscosity. In contrast, the comparative examples did not provide satisfactory results.

Claims

1. A water-soluble polyester as a dispersant and water are included, The water-soluble polyester contains, as constituent monomers in a single molecule, a polyol component having a plurality of hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having a plurality of carboxyl groups and a salt of an anionic functional group.

2. 2. The dispersant-containing liquid according to claim 1, wherein the proportion of the monomer having an anionic functional group in all monomers constituting the water-soluble polyester is 10 mol % or more and 60 mol % or less.

3. 3. The dispersant-containing liquid according to claim 2, wherein the proportion of the monomer having an anionic functional group in all monomers constituting the water-soluble polyester is 15 mol % or more and 30 mol % or less.

4. The dispersant-containing liquid according to claim 1 or 2, wherein the water-soluble polyester contains a monomer having an aromatic ring as a constituent monomer.

5. 5. The dispersant-containing liquid according to claim 4, wherein the proportion of the aromatic ring-containing monomer in all monomers constituting the water-soluble polyester is 40 mol % or more and 80 mol % or less.

6. The water-soluble polyester contains at least one selected from the group consisting of a salt of 2-[bis(2-hydroxyethyl)amino]ethanesulfonic acid and a salt of dimethylolpropionic acid as the polyol component having a salt of the anionic functional group, and at least one selected from the group consisting of a salt of sulfosuccinic acid and a salt of β-alaninediacetic acid as the polycarboxylic acid component having a salt of the anionic functional group, and at least one selected from the group consisting of terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 1,4-benzenedimethanol as the monomer having an aromatic ring, and further contains at least one selected from the group consisting of adipic acid, 1,2-cyclohexanedicarboxylic acid, diethylene glycol, ethylene glycol, and 1,2-cyclohexanedimethanol as other monomers, the dispersant-containing liquid according to claim 4.

7. 3. The dispersant-containing liquid according to claim 1, wherein the water-soluble polyester contains, as constituent monomers, the polyol component having at least one of a sulfonate and a carboxylate, and the polycarboxylic acid component having at least one of a sulfonate and a carboxylate.

8. The ink contains a water-soluble polyester as a dispersant, water, and a colorant as a dispersoid, The water-soluble polyester dispersion contains, as constituent monomers in a single molecule, a polyol component having a plurality of hydroxyl groups and a salt of an anionic functional group, and a polycarboxylic acid component having a plurality of carboxyl groups and a salt of an anionic functional group.

9. The dispersion of claim 8 , wherein the dispersion is an ink-jet composition.

10. 10. The dispersion of claim 8 or 9, further comprising a humectant.

11. 10. The dispersion of claim 8 or 9, further comprising a surface tension modifier.

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