Dispersant-containing liquids and inkjet compositions

Abstract

To provide a dispersion excellent both in dispersion stability and drying resistance of a dispersoid and to provide a dispersant-containing liquid which can be suitably used for the preparation of the dispersion.SOLUTION: There is provided a dispersion containing a polyester as a dispersant, water, a dispersoid and a solvent, wherein the polyester has a carboxyl group and a sulfo group which do not constitute an ester bond and the solvent contains a polyol having a log P of -2.0 or more and 0.0 or less. The ratio of the content of a monomer having a carboxyl group to the content of a monomer having a sulfo group in the polyester is preferably 50% or more and 200% or less in a molar ratio.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a dispersant-containing liquid and a dispersion liquid.

Background Art

[0002] A dispersion liquid in which a dispersoid is dispersed in a dispersion medium containing water is used in various applications. Examples of such a dispersion liquid include ink in which a coloring material is dispersed in a dispersion medium containing water.

[0003] In such a dispersion liquid, a dispersant may be added for the purpose of improving the dispersibility of the dispersoid. For example, an inkjet recording dispersion dye ink containing water, a water-soluble organic solvent, a dispersion 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

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventionally, it has been difficult to achieve both the drying resistance of the dispersion liquid and the dispersion stability of the dispersoid in the dispersion liquid.

Means for Solving the Problems

[0006] The present invention has been made to solve the above problems and can be realized as the following application examples.

[0007] The dispersant-containing liquid according to the application example of the present invention contains a polyester as a dispersant, water, and a solvent. The polyester has carboxyl groups and sulfo groups that do not constitute ester bonds. The solvent contains a polyol having a logP of -2.0 or higher and 0.0 or lower.

[0008] The dispersion according to an example of the present invention comprises a polyester as a dispersant, water, a dispersed phase, and a solvent. The polyester has carboxyl groups and sulfo groups that do not constitute ester bonds. The solvent contains a polyol having a logP of -2.0 or higher and 0.0 or lower. [Modes for carrying out the invention]

[0009] 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. The dispersant-containing liquid of the present invention comprises a polyester as a dispersant, water, and a solvent. The polyester has carboxyl groups and sulfo groups that do not constitute ester bonds, and the solvent contains a polyol having a logP of -2.0 or more and 0.0 or less.

[0010] This configuration allows for sufficiently excellent water solubility of the polyester as a dispersant, resulting in excellent dispersion stability of the dispersed phase and drying resistance of the dispersion when a dispersion is prepared using the dispersant-containing liquid. Indicators of drying resistance include the difficulty of drying the dispersion, and the redispersibility and resolubility of solids precipitated by drying. Furthermore, when preparing a dispersion using the dispersant-containing liquid, if the substances to be dispersed are crushed or pulverized in the dispersant-containing liquid, the wetting of the dispersed phase, particularly the colorant described later, by the dispersant-containing liquid makes crushing and pulverization easier, thus shortening the time required to prepare the dispersion. Moreover, when using an organic colorant as the dispersed phase in the preparation of the dispersion, the affinity and adsorption properties for the organic colorant do not compete with those of the added humectants or surface tension modifiers, and therefore do not adversely affect the dispersion stability of the organic colorant, making this configuration preferable.

[0011] Conversely, if the above conditions are not met, satisfactory results cannot be obtained. For example, if the polyester used as a dispersant in the dispersant-containing liquid has only one of either a carboxyl group or a sulfo group that does not constitute an ester bond, the water solubility of the polyester cannot be made sufficiently good, and the dispersion stability of the dispersed phase when a dispersion is prepared using the dispersant-containing liquid cannot be made sufficiently good. Furthermore, the drying resistance of the dispersion will also be poor.

[0012] Furthermore, if the dispersant-containing solution does not contain a polyol with a logP of -2.0 or higher and 0.0 or lower, the dispersion stability of the dispersed phase cannot be sufficiently good when a dispersion is prepared using the dispersant-containing solution. In addition, the drying resistance of the dispersion will also be poor.

[0013] In particular, when a polyol having a logP less than -2.0 or a polyol having a logP greater than 0.0 is used instead of a polyol having a logP of -2.0 or more and 0.0 or less, the lipophilicity of the polyol becomes too low or too high, so that when a dispersion liquid in which a dispersoid is dispersed is prepared using a dispersant-containing liquid, the dispersion stability of the dispersoid and the drying resistance of the dispersion liquid are sharply reduced.

[0014] Note that logP indicates the octanol / water partition coefficient. Further, the polyester has a carboxyl group and a sulfo group that do not constitute an ester bond, and at least a part of the carboxyl group and the sulfo group may be in the form of a salt, and particularly preferably in the form of a salt with a monovalent inorganic base.

[0015] <1-1>Water The dispersant-containing liquid of the present invention contains water. The water mainly has a function of imparting fluidity to the dispersant-containing liquid and a dispersion liquid prepared using the dispersant-containing liquid, and functions as a dispersion medium and a solvent. Preferably, ion-exchanged water, pure water, or ultrapure water is used as the water.

[0016] The lower limit of the water content in the dispersant-containing liquid is not particularly limited, but is preferably 30.0% by mass, more preferably 35.0% by mass, and even more preferably 40.0% by mass. The upper limit of the water content in the dispersant-containing liquid is not particularly limited, but is preferably 93.0% by mass, more preferably 90.0% by mass, and even more preferably 87.0% by mass.

[0017] Thereby, the viscosity of the dispersant-containing liquid can be more reliably adjusted to a suitable value. Further, the dispersion stability of the dispersoid in the dispersion liquid prepared using the dispersant-containing liquid can be made more excellent.

[0018] <1-2>Polyester as a Dispersant Polyester is a general term for polymer materials having an ester bond in the main chain. Generally, it contains a chemical structure formed by the dehydration condensation of a polyol component having a plurality of hydroxyl groups in the molecule and a polycarboxylic acid component having a plurality of carboxyl groups in the molecule.

[0019] In particular, the dispersant-containing liquid of the present invention contains a polyester having a carboxyl group and a sulfonic group that do not form an ester bond as a dispersant.

[0020] The carboxyl group and the sulfonic group that do not form an ester bond may be present at any site of the polyester molecule, and may be present in the same monomer constituting the polyester. However, it is preferable that the carboxyl group that does not form an ester bond and the sulfonic group are present in different monomers constituting the polyester. In other words, the polyester preferably has, as a constituent monomer, a first monomer having a carboxyl group that does not form an ester bond and a second monomer having a sulfonic group.

[0021] Thereby, the dispersion stability of the dispersoid in the dispersion prepared using the dispersant-containing liquid can be made even more excellent.

[0022] Examples of first monomers having carboxyl groups that do not constitute ester bonds include trivalent or higher carboxylic acid compounds, their lower alkyl diesters, anhydrides, carboxyl group-containing polyols, and salts thereof, and one or more selected from these can be used in combination. Examples of trivalent or higher carboxylic acid compounds include tricarbaryl acid, β-alanine diacetic acid, trimellitic acid, trimesic acid, pyromellitic acid, and merophanic acid. Examples of carboxyl group-containing polyols include N,N-bis(2-hydroxyethyl)-β-alanine and N,N-bis(2-hydroxyethyl)succinamic acid. Furthermore, when a resin end modifier described later is used as the first monomer, for example, a divalent polycarboxylic acid monomer described later can be used as the resin end modifier.

[0023] Examples of the second monomer having a sulfo group include sulfonated polycarboxylic acid monomers, their lower alkyl esters, anhydrides, and sulfonated polyol monomers, and one or more selected from these can be used in combination. Examples of the sulfonated polycarboxylic acid monomers include sulfisophthalic acid, sulfoterephthalic acid, sulfophthalic acid, sulfosuccinic acid, sulfomaronic acid, 2,3-disulfosuccinic acid, sulfotartaric acid, sulfomalacic acid, sulfomaleic acid, sulfofumaric acid, 1-sulfo-1,2-cyclohexanedicarboxylic acid, and 3-(sodiooxysulfonyl)glutaric acid. Examples of the sulfonated polyol monomers include 2,3-dihydroxy-1-propanesulfonic acid, 3-[bis(2-hydroxyethyl)amino]-1-propanesulfonic acid, and 2-hydroxy-3-[bis(2-hydroxyethyl)amino]-1-propanesulfonic acid.

[0024] The lower limit of the ratio of the sum of the content of the first monomer and the content of the second monomer relative to the total monomers constituting the polyester is preferably 2.0 mol%, more preferably 4.0 mol%, and even more preferably 6.0 mol%. The upper limit of the ratio of the sum of the content of the first monomer and the content of the second monomer relative to the total monomers constituting the polyester is preferably 20.0 mol%, more preferably 18.0 mol%, and even more preferably 16.0 mol%.

[0025] This configuration allows for improved water solubility of the polyester as a dispersant, and when a dispersion is prepared using a dispersant-containing liquid, the dispersion stability of the dispersed phase and the drying resistance of the dispersion can be improved. Furthermore, when the dispersion is an inkjet composition, the ejection stability of the inkjet composition by the inkjet method can be improved, while also improving the color development of the recording section formed using the inkjet composition. In addition, the water resistance of the recording section formed by the inkjet composition can be improved.

[0026] The lower limit of the ratio of the monomer having a carboxyl group to the monomer having a sulfo group in the polyester is preferably 50%, more preferably 55%, and even more preferably 60% in molar ratio. The upper limit of the ratio of the monomer having a carboxyl group to the monomer having a sulfo group in the polyester is preferably 200%, more preferably 150%, and even more preferably 120% in molar ratio.

[0027] This makes it possible to improve the water solubility of polyester as a dispersant, and to improve the dispersion stability of the dispersed phase and the drying resistance of the dispersion when a dispersion is prepared using a dispersant-containing liquid.

[0028] Carboxyl groups and sulfo groups that do not constitute an ester bond may, for example, be present in the side chains of the polyester molecule or at the ends of the main chain of the polyester.

[0029] If carboxyl groups that do not constitute an ester bond are present in the side chains of the polyester molecule, these carboxyl groups can be suitably introduced, for example, in the synthesis of the polyester by using trivalent or higher polycarboxylic acids, their lower alkyl esters, or acid anhydrides as polycarboxylic acid monomers, or by using compounds having two or more hydroxyl groups and one or more carboxyl groups as polyol monomers.

[0030] Furthermore, if carboxyl groups that do not constitute ester bonds are present at the ends of the polyester main chain, these carboxyl groups can be suitably introduced by, for example, adjusting the reaction conditions to synthesize a polymer so that hydroxyl groups are present at the ends, as described in the specific examples below, and then reacting the hydroxyl groups at the ends of the polymer with carboxyl groups of a divalent or higher polycarboxylic acid monomer used as a resin end modifier. In this case, lower alkyl esters or acid anhydrides of the divalent or higher polycarboxylic acid monomer can also be used as the resin end modifier.

[0031] When a sulfo group is present in the side chain of the polyester molecule, the carboxyl group can be suitably introduced, for example, in the synthesis of the polyester by using a divalent or higher polycarboxylic acid having a sulfo group, its lower alkyl ester, or an acid anhydride as a polycarboxylic acid monomer, or by using a compound having a sulfo group and two or more hydroxyl groups as a polyol monomer.

[0032] Furthermore, if a sulfo group is present at the end of the polyester main chain, the sulfo group can be suitably introduced by, for example, adjusting the reaction conditions to synthesize a polymer so that a hydroxyl group is present at the end, as will be explained in the specific examples described later, and then reacting the hydroxyl group at the end of the polymer with the carboxyl group of a resin end modifier having a carboxyl group and a sulfo group.

[0033] Examples of polycarboxylic acid monomers include aromatic polycarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, 2,5-norbornanedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 4,4'-sulfonyldibenzoic acid, and 2,5-naphthalenedicarboxylic acid; aliphatic polycarboxylic acids such as 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; and their lower alkyl esters and anhydrides. One or more selected from these can be used in combination.

[0034] Examples of polyol 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, and 1,3-cyclohexanedimethanol. Examples include aliphatic polyols such as 1,4-cyclohexanedimethanol and 2,2'-bis(4-hydroxycyclohexyl)isopropane, aromatic polyols such as 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, and one or more of these can be selected and used in combination.

[0035] The polyester preferably contains a water-insoluble aromatic monomer that does not have a water-soluble group and has an aromatic ring.

[0036] As a result, when a dispersion is prepared using the dispersant-containing liquid of the present invention and highly lipophilic materials such as oil dyes and disperse dyes, the disperse phase composed of the materials can be suitably adsorbed by the polyester, thereby improving the dispersion stability of the disperse phase in the dispersion.

[0037] Examples of the water-soluble groups include sulfo groups, carboxyl groups, and phosphate groups. Furthermore, examples of aromatic rings possessed by water-insoluble aromatic monomers include phenyl groups, biphenyl groups, naphthyl groups, and functional groups in which at least some of the hydrogen atoms of these functional groups are substituted with other atoms or groups of atoms. One or more of these can be selected and used in combination.

[0038] The lower limit of the content of the water-insoluble aromatic monomer relative to the total monomers constituting the polyester is preferably 25 mol%, more preferably 30 mol%, and even more preferably 33 mol%. The upper limit of the content of the water-insoluble aromatic monomer relative to the total monomers constituting the polyester is preferably 75 mol%, more preferably 70 mol%, and even more preferably 65 mol%.

[0039] As a result, when a dispersion is prepared using the dispersant-containing liquid of the present invention and a highly lipophilic material such as an oil dye or disperse dye, the hydrophobic adsorption force of polyester to the dispersed phase composed of the aforementioned material can be made sufficiently large, and the flexibility of polyester molecules can be improved, allowing the polyester molecules to more favorably conform to the surface shape of the dispersed phase. Consequently, the dispersed phase can be adsorbed more favorably onto the polyester, and the dispersion stability of the dispersed phase in the dispersion can be further improved.

[0040] The lower limit of the number-average molecular weight of the polyester is preferably 1,500, more preferably 1,800, and even more preferably 2,000. The upper limit of the number-average molecular weight of the polyester is preferably 10,000, more preferably 8,000, and even more preferably 7,000.

[0041] This configuration allows for improved water solubility of the polyester as a dispersant, and when a dispersion is prepared using a dispersant-containing liquid, the dispersion stability of the dispersed phase and the drying resistance of the dispersion can be improved. Furthermore, the viscosity of the dispersant-containing liquid and the dispersion prepared using the dispersant-containing liquid can be adjusted to a more suitable range. For example, if the dispersion is an inkjet composition, the ejection stability of the inkjet composition by the inkjet method can be improved, while the color development of the recording section formed using the inkjet composition can be improved.

[0042] The lower limit of the polyester content 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. The upper limit of the polyester content 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.

[0043] This makes it easier to adjust the viscosity of the dispersant-containing liquid and the dispersion prepared using the dispersant-containing liquid to a suitable range, improving the ease of handling of the dispersant-containing liquid and the dispersion. Furthermore, it improves the dispersion stability of the dispersed phase and the drying resistance of the dispersion when a dispersion is prepared using the dispersant-containing liquid.

[0044] <1-3> Solvent The dispersant-containing liquid of the present invention contains a solvent, which is a liquid component other than water, in addition to water. The solvent mainly functions to impart fluidity to the dispersant-containing liquid or the dispersion prepared using the dispersant-containing liquid, and functions as a dispersion medium or solvent.

[0045] The solvent contains a polyol having a logP of -2.0 or higher and 0.0 or lower. The lower limit of logP of the polyol may be -2.0, but is preferably -1.9, more preferably -1.8, and even more preferably -1.7. The upper limit of logP of the polyol may be 0.0, but is preferably -0.1, more preferably -0.2, and even more preferably -0.3. This makes the aforementioned effects even more pronounced.

[0046] Examples of the polyols include 1,2-pentanediol (logP 0.0), 1,6-hexanediol (logP -0.1), neopentyl glycol (logP -0.34), trimethylolpropane (logP -0.9), 1,2-propanediol (logP -1.1), trimethylolethane (logP -1.3), ethylene glycol (logP -1.36), triethylene glycol (logP -2.0), and others. One or more of these can be selected and used in combination.

[0047] The content of the polyol in the dispersant-containing liquid is not particularly limited, but the lower limit of the polyol content per 100.0 parts by mass of polyester is preferably 1.0 part by mass, more preferably 1.2 parts by mass, and even more preferably 1.5 parts by mass. The upper limit of the polyol content per 100.0 parts by mass of polyester is preferably 50.0 parts by mass, more preferably 30.0 parts by mass, and even more preferably 20.0 parts by mass.

[0048] This makes it possible to adjust the viscosity of the dispersant-containing liquid or the dispersion prepared using the dispersant-containing liquid to a more suitable range. For example, if the dispersion is an inkjet composition, it is possible to improve the ejection stability of the inkjet composition by the inkjet method while also improving the color development of the recording section formed using the inkjet composition.

[0049] The solvent constituting the dispersant-containing liquid of the present invention may contain the polyol, and may also contain other solvent components. For example, the solvent constituting the dispersant-containing liquid of the present invention may, in addition to the polyol, contain other solvent components such as polyol components whose logP is not within the range of -2.0 to 0.0, or components other than polyols.

[0050] However, the content of the polyol relative to the total solvent constituting the dispersant-containing liquid of the present invention is preferably 50.0% by mass or more, more preferably 70.0% by mass or more, and even more preferably 90.0% by mass or more.

[0051] <1-4> Basic substances In addition to the components described above, the dispersant-containing liquid of the present invention may further contain a basic substance as a pH adjuster.

[0052] This allows the pH range of the dispersant-containing solution to be adjusted to a suitable weakly basic range, ensuring a more favorable dissolution state of the polyester in the dispersant-containing solution. For example, problems such as aggregation and sedimentation due to the insolubilization of the polyester can be more effectively prevented. As a result, for example, when a dispersion is prepared using the dispersant-containing solution, the dispersion stability of the dispersed phase and the drying resistance of the dispersion can be improved. Furthermore, if the dispersion is an inkjet composition, the ejection stability of the inkjet composition by the inkjet method can be improved.

[0053] Examples of basic substances include monovalent inorganic bases, divalent inorganic bases, and water-soluble organic amines, and one or more of these can be selected and used in combination.

[0054] Examples of monovalent inorganic bases include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, as well as ammonia. Alkali metal hydroxides are particularly preferred, and sodium hydroxide is more preferred. Examples of divalent inorganic bases include hydroxides of alkaline earth metals.

[0055] As water-soluble organic amines, for example, organic amines with a solubility in water at 20°C of 10 g / 100 g water or more can be used. Specific examples of water-soluble organic amines include alkylamines such as monoethylamine, diethylamine, triethylamine, monomethylamine, dimethylamine, and trimethylamine, as well as diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, butyldiethanolamine, ethyldiethanolamine, and 2-amino-2-ethyl-1,3-propanediol.

[0056] In particular, hydroxyamines are preferred as water-soluble organic amines, diolamines or triolamines are more preferred, and triethanolamine is even more preferred. This makes it possible to increase the boiling point of water-soluble organic amines while also achieving high hygroscopicity, thereby more effectively preventing the precipitation of solids due to unintended drying of dispersant-containing solutions or dispersions prepared using dispersant-containing solutions.

[0057] Furthermore, the dispersant-containing solution preferably contains a monovalent inorganic base and a water-soluble organic amine as basic substances.

[0058] As a result, when forming a salt with the anionic polyester, the strong water solubility of the monovalent inorganic base salt and the affinity with additives used in the preparation of the dispersion using the water-soluble organic amine salt allow the polyester to be stably dissolved in the dispersion, thereby improving the long-term stability of the dispersion.

[0059] The basic substance may be used during the synthesis of the polyester, for example, so that the monomer is in the form of a salt, or it may be mixed with the synthesized polyester.

[0060] <1-5> Other ingredients The dispersant-containing liquid 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.

[0061] Other components include, for example, dispersants and resin components other than the polyester mentioned above, humectants, surface tension modifiers, preservatives, chelating agents, etc., and one or more of these can be selected and used in combination.

[0062] However, the dispersant-containing liquid of the present invention does not contain a dispersed phase. A dispersion containing a dispersed phase in addition to the components of the dispersant-containing liquid of the present invention described above is the dispersion liquid of the present invention described later.

[0063] Furthermore, 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.

[0064] <1-6> Others The dispersant-containing liquid of the present invention preferably satisfies the following conditions. 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.

[0065] This ensures a more favorable dissolution state for the polyester, and for example, it can more effectively prevent problems such as aggregation and sedimentation due to the insolubilization of the polyester. As a result, for example, when a dispersion is prepared using a dispersant-containing liquid, the dispersion stability of the dispersed phase and the drying resistance of the dispersion can be improved. Furthermore, if the dispersion is an inkjet composition, the ejection stability of the inkjet composition by the inkjet method can be improved.

[0066] The dispersant-containing liquid of the present invention can be suitably prepared, for example, by adding necessary components such as a solvent containing the aforementioned polyol and water to the polyester obtained by the condensation reaction and stirring. Heating may also be performed during stirring as necessary.

[0067] <2> dispersion liquid Next, the dispersion of the present invention will be described.

[0068] The dispersion of the present invention comprises a polyester as a dispersant, water, a dispersed phase, and a solvent. The polyester has carboxyl groups and sulfo groups that do not constitute ester bonds, and the solvent contains a polyol having a logP of -2.0 or more and 0.0 or less.

[0069] This configuration allows for excellent water solubility of the polyester as a dispersant, resulting in superior dispersion stability of the dispersed phase in the dispersion and excellent drying resistance of the dispersion.

[0070] <2-1>Water The dispersion of the present invention contains water. The water primarily serves to impart fluidity to the dispersion and functions as a dispersion medium and solvent. For the water used, it is preferable to use deionized water, pure water, or ultrapure water.

[0071] The lower limit of the water content in the dispersion is not particularly limited, but is preferably 35.0% by mass, more preferably 40.0% by mass, and even more preferably 45.0% by mass. The upper limit of the water content in the dispersant-containing solution is not particularly limited, but is preferably 93.0% by mass, more preferably 90.0% by mass, and even more preferably 87.0% by mass.

[0072] This allows for more reliable adjustment of the viscosity of the dispersion to a suitable value. Furthermore, it improves the dispersion stability of the dispersed phase within the dispersion.

[0073] <2-2> Polyester as a dispersant The dispersion of the present invention contains a polyester having carboxyl groups and sulfo groups that do not constitute ester bonds as a dispersant.

[0074] Such polyesters preferably satisfy the same conditions as described in <1-2> above. This will produce the same effect as described above.

[0075] The lower limit of the polyester content in the dispersion is preferably 0.3% by mass, more preferably 0.4% by mass, and even more preferably 0.5% by mass. The upper limit of the polyester content in the dispersion is preferably 17.5% by mass, more preferably 15.0% by mass, and even more preferably 14.0% by mass.

[0076] This makes it easier to adjust the viscosity of the dispersion to a suitable range, improving the ease of handling the dispersion, and also improving the dispersion stability of the dispersed phase and the drying resistance of the dispersion.

[0077] Furthermore, the lower limit of the polyester content per 100.0 parts by mass of dispersed phase 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. Furthermore, the upper limit of the polyester content per 100.0 parts by mass of dispersed phase 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.

[0078] This makes it easier to adjust the viscosity of the dispersion to a suitable range, improving the ease of handling the dispersion, and also improving the dispersion stability of the dispersed phase and the drying resistance of the dispersion.

[0079] <2-3> Solvent The dispersion of the present invention contains a solvent, which is a liquid component other than water, in addition to water. The solvent primarily functions to impart fluidity to the dispersion and functions as a dispersion medium and solvent.

[0080] The solvent contains a polyol having a logP of -2.0 or higher and 0.0 or lower. Such polyols preferably satisfy the same conditions as those described in <1-3> above. This will produce the same effect as described above.

[0081] The content of the polyol in the dispersion is not particularly limited, but the lower limit of the polyol content per 100.0 parts by mass of polyester is preferably 1.0 part by mass, more preferably 1.2 parts by mass, and even more preferably 1.5 parts by mass. The upper limit of the polyol content per 100.0 parts by mass of polyester is preferably 50.0 parts by mass, more preferably 30.0 parts by mass, and even more preferably 20.0 parts by mass.

[0082] This allows the viscosity of the dispersion to be adjusted to a more suitable range. For example, if the dispersion is an inkjet composition, it is possible to improve the ejection stability of the inkjet composition by the inkjet method while also improving the color development of the recording section formed using the inkjet composition.

[0083] The solvent constituting the dispersion of the present invention may contain the polyol, and may also contain other solvent components. However, the content of the polyol relative to the total solvent constituting the dispersion of the present invention is preferably 50.0% by mass or more, more preferably 70.0% by mass or more, and even more preferably 90.0% by mass or more.

[0084] <2-4>Dispersion The dispersion of the present invention contains a dispersed phase. The dispersed phase can be any material that is dispersed in the dispersion, and can be composed of various materials depending on the application of the dispersion. Examples of constituent materials for the dispersed phase include resin materials that are poorly soluble in water, and various colorants such as pigments, disperse dyes, sublimation dyes, and oil-soluble dyes.

[0085] Examples of pigments include quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ancenthrone 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.

[0086] 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, 180, etc. 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, 5 Examples of cyan pigments include 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 Bat Blue 4, 60, and 63. Other color pigments include, for example, CI Pigment Orange 5, 13, 16, 17, 36, 43, 51; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36; and CI Pigment Violet 1, 3, 5:1, 16, 19, 23, 38.

[0087] Examples of disperse dyes include CI Disperse Red 60, 82, 86, 86:1, 167:1, 279, 364; CI Disperse Yellow 54, 64, 71, 86, 114, 153, 232, 233, 245; CI Disperse Blue 27, 60, 73, 77, 77:1, 87, 257, 359, 367; CI Disperse Violet 26, 33, 36, 57; and CI Disperse Orange 30, 41, 61.

[0088] Examples of oil-soluble dyes include CI Solvent Yellow 16, 21, 25, 29, 33, 51, 56, 82, 88, 89, 150, 163; CI Solvent Red 7, 8, 18, 24, 27, 49, 109, 122, 125, 127, 130, 132, 135, 218, 225, 230; CI Solvent Blue 14, 25, 35, 38, 48, 67, 68, 70, 132; and CI Solvent Black 3, 5, 7, 27, 28, 29, 34.

[0089] The dispersed phase contained in the dispersion of the present invention is preferably either a disperse dye or an oil-soluble dye.

[0090] This makes it possible to improve the dispersion stability of the dispersed phase in the dispersion. Furthermore, the dispersion of the present invention can be suitably applied to, for example, ink compositions, particularly inkjet compositions, and the color development and other properties of the recording section formed using such compositions can be improved.

[0091] The content of the dispersed phase in the dispersion of the present invention is not particularly limited, but the lower limit of the content of the dispersed phase in the dispersion of the present invention is preferably 1.0% by mass, more preferably 2.0% by mass, and even more preferably 3.0% by mass. Furthermore, the upper limit of the content of the dispersed phase in the dispersion of the present invention is preferably 40.0% by mass, more preferably 35.0% by mass, and even more preferably 30.0% by mass.

[0092] This makes it possible to achieve a sufficiently high content of the dispersed phase in the dispersion while also improving the dispersion stability of the dispersed phase. Furthermore, when the dispersed phase is dispersed using a disperser such as a bead mill, for example, it becomes easier to adjust the viscosity of the resulting dispersion to a more suitable range. In addition, when the dispersion is an ink composition such as an inkjet composition, it is possible to improve the color development of the recording section formed using the ink composition.

[0093] <2-5> Basic substances In addition to the components described above, the dispersion of the present invention may further contain a basic substance as a pH adjuster.

[0094] This allows the pH range of the dispersion to be adjusted to a suitable range, ensuring a more favorable dissolution state of the polyester in the dispersion, and more effectively preventing problems such as aggregation and sedimentation due to the insolubilization of the polyester. As a result, for example, the dispersion stability of the dispersed phase in the dispersion and the drying resistance of the dispersion can be improved. Furthermore, if the dispersion is an inkjet composition, the ejection stability of the inkjet composition by the inkjet method can be improved.

[0095] Such basic substances are preferably those that satisfy the same conditions as described in <1-4> above. This will produce the same effect as described above.

[0096] <2-6> Moisturizer The dispersion of the present invention may contain a humectant.

[0097] Examples of humectants include polyols such as 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, tripropylene glycol, isobutylene glycol, glycerin, diglycerin, mesoerythritol, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipentaerythritol; monosaccharides such as 2-glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose; disaccharides, oligosaccharides, polysaccharides, and derivatives of these sugars; and betaines such as glycine and trimethylglycine. One or more of these can be selected and used in combination.

[0098] The content of the humectant in the dispersion of the present invention is not particularly limited, but the lower limit of the humectant content in the dispersion of the present invention is preferably 3.0% by mass, more preferably 5.0% by mass, and even more preferably 7.0% by mass. Furthermore, the upper limit of the humectant content in the dispersion of the present invention is preferably 40.0% by mass, more preferably 35.0% by mass, and even more preferably 30.0% by mass.

[0099] <2-7> Surface tension modifier The dispersion of the present invention may contain a surface tension modifier. Examples of surface tension modifiers include surfactants and water-soluble compounds with a logP value in the range of greater than 0.0 and less than or equal to 4.0.

[0100] Examples of surfactants include cationic surfactants, anionic surfactants, and nonionic surfactants. However, nonionic surfactants are particularly preferred in order to minimize the influence on the solubility of the polyester which is dissolved by anionic surfactants.

[0101] Examples of nonionic, nonreactive surfactants include silicone-based surfactants, fluorine-based surfactants, and acetylene glycol-based surfactants.

[0102] Examples of silicone-based surfactants include: BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348, BYK-349, BYK-3455 from BIC Chemie Japan; Silface SAG503A, SAG002, SAG005, SAG014 from Nisshin 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, KF-6012 from Shin-Etsu Chemical Co., Ltd.

[0103] Examples of fluorine-based surfactants include FC-4430 and FC-4432 from 3M Japan, Megafac F-444, F-477, F-553, and F-556 from DIC Corporation, and Surflon S-241, S-242, S-243, and S-386 from AGC Seimi Chemical Co., Ltd.

[0104] Examples of acetylene glycol-based surfactants include Surfinol 82, 465, 485, 2502, Olfin E1010, E1020, PD-002W, PD-004, EXP4001, EXP4002, EXP4123, EXP4300 from Nisshin Chemical Industry Co., Ltd., and Acetylenel E00, E103T, E40, E60, E100, E200 from Kawaken Fine Chemical Co., Ltd.

[0105] Examples of water-soluble compounds with a logP value greater than 0.0 and less than or equal to 4.0 include lower alcohols such as 2-propanol (logP 0.05), 1-propanol (logP 0.25), 2-butanol (logP 0.6), and 1-butanol (logP 0.88); glycol monoethers such as diethylene glycol monobutyl ether (logP 0.4), triethylene glycol monobutyl ether (logP 0.5), propylene glycol monobutyl ether (logP 1.2), dipropylene glycol monobutyl ether (logP 1.5), ethylene glycol mono-2-ethylhexyl ether (logP 2.8), and diethylene glycol mono-2-ethylhexyl (logP 2.4); lower alkyl 1,2-diols such as 1,2-pentanediol (logP 0.06) and 1,2-hexanediol (logP 0.6); and glycerin monobutyl ether (logP Examples include glycerin monoethers such as glycerin-2-ethylhexyl ether (logP 2.5), 0.6), and glycerin-2-ethylhexyl ether (logP 2.5).

[0106] 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% by mass, more preferably 0.3% by mass, and even more preferably 1.0% by mass. Furthermore, the upper limit of the content of the surface tension modifier in the dispersion of the present invention is preferably 10.0% by mass, more preferably 8.0% by mass, and even more preferably 6.0% by mass.

[0107] <2-8> 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.

[0108] Other components include, for example, preservatives, chelating agents, dispersants other than the polyester, and resin components, and one or more of these can be selected and used in combination.

[0109] By including preservatives, for example, spoilage of the dispersion by microorganisms can be prevented, and the precipitation and aggregation of solids in the dispersion can be more effectively prevented.

[0110] Examples of preservatives include methylisothiazolinone, chloromethylisothiazolinone, octylisothiazolinone, dichlorooctylisothiazolinone, benzisothiazolinone, dicyclohexylamine, iodide propynyl butylcarbamate, and diethylene oxidide.

[0111] By including a chelating agent, for example, polyvalent cations in the dispersion can be trapped, making it possible to more effectively prevent the precipitation and aggregation of solid components in the dispersion.

[0112] Examples of chelating agents include ethylenediaminetetratetraacetate, diethyltriaminepentaacetate, pentetate, iminodisuccinate, and aspartate diacetate.

[0113] 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.

[0114] <2-9> Others The dispersion of the present invention preferably satisfies the following conditions. 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. 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.

[0115] This ensures a more favorable dissolution state for the polyester, and for example, it can more effectively prevent problems such as aggregation and sedimentation due to the insolubilization of the polyester. As a result, for example, the dispersion stability of the dispersed phase in the dispersion and the drying resistance of the dispersion can be improved. Furthermore, if the dispersion is an inkjet composition, the ejection stability of the inkjet composition by the inkjet method can be improved.

[0116] The dispersion of the present invention may be used for any purpose, such as paints or various ink compositions, but it is preferably an inkjet composition.

[0117] In inkjet compositions, sedimentation and aggregation of the dispersed phase, or precipitation of solid components within the inkjet head or flow path, significantly affect the ejection stability 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 require a high level of both dispersion stability and drying resistance of the dispersed phase. In contrast, the present invention can suitably achieve both dispersion stability and drying resistance of the dispersed phase. That is, the effects of the present invention are more pronounced when the dispersion is an inkjet composition. In this specification, the term "inkjet composition" includes not only the inkjet ink itself ejected by the inkjet method, but also, for example, the stock solution of inkjet ink used in the preparation of an inkjet by mixing it with other components.

[0118] The lower limit of the viscosity of the dispersion of the present invention at 20°C is not particularly limited, but is preferably 2.0 mPa·s, and more preferably 3.0 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 9.0 mPa·s, more preferably 8.0 mPa·s, and even more preferably 7.0 mPa·s.

[0119] This makes it possible to improve the discharge stability of the dispersion liquid of the present invention, for example, when it is an inkjet composition.

[0120] The viscosity was measured at 20°C using a viscoelasticity tester such as the MCR-300 manufactured by Pysica, with a shear rate of 10 [s]. -1 ] to 1000[s -1 The viscosity can be measured by increasing the setting and reading the viscosity when the Shear Rate is 200.

[0121] 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, more preferably 40 mN / m, and even more preferably 30 mN / m.

[0122] As a result, for example, when the dispersion of the present invention is an inkjet composition, clogging of the nozzles of an inkjet recording device becomes less likely, and the discharge stability of the dispersion of the present invention is further improved. Furthermore, even if nozzle clogging occurs, the ability to recover by capping the nozzle, i.e., by capping, can be improved.

[0123] Furthermore, the surface tension can be measured using the Wilhelmy method. For measuring surface tension, a surface tension meter such as the CBVP-7 manufactured by Kyowa Interface Science Co., Ltd. can be used.

[0124] When the dispersion of the present invention is an inkjet ink, the ink is typically stored in a container such as a cartridge, bag, or tank and applied to an inkjet recording device. In other words, the recording device according to the present invention is equipped with a container such as an ink cartridge that stores the inkjet ink as the dispersion of the present invention.

[0125] The dispersion of the present invention can be prepared, for example, by mixing the dispersant-containing liquid of the present invention described above with a substance to be dispersed. At this time, a bead mill or the like may be used with the dispersant-containing liquid of the present invention and the substance to be dispersed mixed together. This allows for efficient micronization of the substance to be dispersed, thereby improving the dispersion stability of the dispersed substance in the dispersion liquid of the present invention.

[0126] Various inorganic beads such as zirconia beads, stainless steel beads, and alumina beads can be suitably used as beads.

[0127] When preparing the dispersion of the present invention, in addition to the dispersant-containing liquid and the substance to be dispersed as described above, components such as water, solvents, humectants, and surface tension modifiers may also be used. When preparing the dispersion of the present invention, heating may be performed as needed.

[0128] Furthermore, the dispersion of the present invention is not limited to those prepared by the method described above. For example, the dispersion of the present invention may be prepared without using the dispersant-containing liquid of the present invention described above, by mixing the polyester obtained by the condensation reaction, the substance to be formed into the dispersion, the solvent containing the polyol described above, water, and other necessary components all at once, or by adding and mixing them sequentially in a predetermined order.

[0129] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto. [Examples]

[0130] Next, specific embodiments of the present invention will be described. <3> Polyester synthesis

[0131] (Synthesis Example 1) In an autoclave, 223.0 parts by mass of terephthalic acid as a polycarboxylic acid monomer, 37.0 parts by mass of sodium 5-sulfoisophthalate as a polycarboxylic acid-type water-soluble monomer, 758.0 parts by mass of ethylene glycol as a polyol, and 5.0 parts by mass of tetrabutoxytitanate as a catalyst were added, and the mixture was heated at 150-200°C for 180 minutes to carry out the esterification reaction.

[0132] Next, at a temperature of 200°C, the pressure of the system was gradually reduced to remove the diol component by distillation, and after 30 minutes, the pressure was reduced to 10 mmHg. The polymerization reaction was then continued for 90 minutes. To this reaction product, 61.0 parts by mass of maleic anhydride, used as a resin end modifier, was added and the reaction was further carried out at 200°C for 60 minutes to introduce carboxyl groups to the polyester ends and obtain a polyester to be used as a dispersant.

[0133] The obtained polyester had a number-average molecular weight of 3,000, a molar ratio of carboxyl groups to sulfo groups of 60%, and a molar ratio of monomers with aromatic rings to the total monomers of the polyester of 37%.

[0134] The number-average molecular weight of the obtained polyester was measured by GPC. Furthermore, the monomer ratio in the polyester was: 1 The measurements were performed using 1H-NMR. The amount of sulfo groups was calculated by measuring the sulfur content using XRF. The amount of carboxyl groups was calculated from the acid value of the polyester. For the polyesters synthesized in the following synthesis examples, the number-average molecular weight, monomer ratio in the polyester, amount of sulfo groups, and amount of carboxyl groups were determined in the same manner.

[0135] (Synthesis examples 2-5) Polyester was obtained in the same manner as in Synthesis Example 1, except that the type and amount of raw material monomers used for polyester synthesis were changed as shown in Table 1.

[0136] (Synthesis Example 6) In an autoclave, 90.0 parts by mass of terephthalic acid and 90.0 parts by mass of isophthalic acid were added as polycarboxylic acid monomers, 37.0 parts by mass of sodium 5-sulfoizophthalate and 52.0 parts by mass of trimellitic anhydride as polycarboxylic acid-type water-soluble monomers, 403.0 parts by mass of ethylene glycol and 240.0 parts by mass of neopentyl glycol as polyols, and 5.0 parts by mass of tetrabutoxytitanate as a catalyst. The mixture was heated at 150°C for 180 minutes to carry out an ester condensation reaction. The pressure of the system was gradually reduced to remove the diol component by distillation, and after 30 minutes, the pressure was increased to 10 mmHg. The polymerization reaction was then continued for 90 minutes to obtain a polyester to be used as a dispersant.

[0137] The obtained polyester had a number-average molecular weight of 10,000, a molar ratio of carboxyl groups to sulfo groups of 100%, and a molar ratio of monomers with aromatic rings to the total monomers of the polyester of 30%.

[0138] (Synthesis Example 7) Polyester was obtained in the same manner as in Synthesis Example 6, except that the type and amount of raw material monomers used for polyester synthesis were changed as shown in Table 1.

[0139] Table 1 summarizes the conditions for the polyesters obtained in the above synthesis examples 1 to 7. The numerical values ​​for "Components used in synthesis" in Table 1 represent the amount of each component used in parts by mass.

[0140] [Table 1]

[0141] <4> Preparation of a dispersant-containing solution (Example A1) In a flask, 80.0 parts by mass of pure water, 1.10 parts by mass of triethanolamine as a basic substance, and 1.0 part by mass of neopentyl glycol as a polyol solvent were added and stirred at 20°C to obtain a homogeneous solution. To this, 15.0 parts by mass of the polyester synthesized in Synthesis Example 1 was added and stirred at 70°C for 60 minutes, and then pure water was added to bring the total volume to 100.0 parts by mass to obtain a dispersant-containing solution.

[0142] (Examples A2-A6) The dispersant-containing solution was prepared in the same manner as in Example A1, except that the types and amounts of each component used in the preparation of the dispersant-containing solution were changed as shown in Table 2.

[0143] (Comparative examples A1~A3) The dispersant-containing solution was prepared in the same manner as in Example A1, except that the types and amounts of each component used in the preparation of the dispersant-containing solution were changed as shown in Table 2.

[0144] Table 2 summarizes the conditions of the dispersant-containing solutions for each of the above examples and comparative examples. The numerical values ​​for "Amount Used" under "Components Used in Preparation" in Table 2 represent the amount of each component used in parts by mass. Furthermore, the turbidity of each dispersant-containing solution was determined according to JIS K0101, and the results under the following criteria are shown in the "Dissolution State" column of Table 2. A lower turbidity indicates better polyester solubility.

[0145] A: Turbidity is less than 50 FTU. B: Turbidity is between 50 FTU and 200 FTU. C: Turbidity is 200 FTU or higher.

[0146] [Table 2]

[0147] <5> Preparation of inkjet ink concentrate as a dispersion (Example B1) 50.0 parts by mass of the dispersant-containing solution prepared in Example A1 and 35.0 parts by mass of pure water were mixed, and 15.0 parts by mass of CI Disperse Blue 359, a disperse dye, was added as a colorant. Using 0.5 mm diameter zirconia balls as a medium, the mixture was dispersed in a bead mill for 2 hours, the beads were separated, and the mixture was filtered through an 8 μm pore size filter to obtain a stock solution for inkjet ink as a dispersion.

[0148] (Examples B2-B6) The inkjet ink stock solution 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 inkjet ink stock solution were changed as shown in Table 3.

[0149] (Comparative examples B1~B3) The inkjet ink stock solution 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 inkjet ink stock solution were changed as shown in Table 3.

[0150] Table 3 summarizes the conditions of the inkjet ink stock solutions for each of the above examples and comparative examples. The numerical values ​​for "Amount Used" under "Components Used in Preparation" in Table 3 represent the amount of each component used in parts by mass. Furthermore, the pH of the inkjet ink stock solutions for each of the above examples at 20°C was within the range of 7.0 to 10.0.

[0151] [Table 3]

[0152] <6> Preparation of inkjet ink as a dispersion (Example C1) 33.0 parts by mass of the inkjet ink stock solution prepared in Example B1, 15.0 parts by mass of glycerin as a humectant, 10.0 parts by mass of triethylene glycol, 0.2 parts by mass of BYK-348 (manufactured by Bic Chemie Japan) as a surface tension modifier, 0.3 parts by mass of Surfinol 465 (manufactured by Nisshin Chemical Industry Co., Ltd.), 4.0 parts by mass of triethylene glycol monobutyl ether, and 0.2 parts by mass of triethanolamine as a basic substance were mixed together. Pure water was then added to bring the total volume to 100.0 parts by mass, and the mixture was stirred for 30 minutes at 20°C. The mixture was then filtered through a 3 μm pore size precision filter to obtain an inkjet ink dispersion.

[0153] (Examples C2-C6) An inkjet ink dispersion was prepared in the same manner as in Example C1, except that the type of inkjet ink stock solution used for preparing the inkjet ink, the types of each additive component, and the amount used were changed as shown in Table 4.

[0154] (Comparative examples C1~C3) An inkjet ink dispersion was prepared in the same manner as in Example C1, except that the type of inkjet ink stock solution used for preparing the inkjet ink, the types of each additive component, and the amount used were changed as shown in Table 4.

[0155] Table 4 summarizes the conditions of the inkjet inks for each of the above examples and comparative examples. The values ​​for "Amount Used" under "Components Used in Preparation" in Table 4 represent the amount of each component used in parts by mass. Furthermore, the pH of the inkjet inks for each of the above examples at 20°C was within the range of 7.0 to 10.0. Also, the viscosity of the inkjet inks for each of the above examples was between 2.0 mPa·s and 9.0 mPa·s. Viscosity was measured using a viscoelasticity tester MCR-300 (manufactured by Pysica) at 20°C with a shear rate of 10 [s]. -1 ] to 1000[s -1The viscosity was measured by increasing the viscosity and reading the value when the shear rate reached 200. In addition, the surface tension of the inkjet inks in each of the above examples was within the range of 23 mN / m to 30 mN / m. The surface tension was measured using a surface tensimeter (CBVP-7, manufactured by Kyowa Interface Science Co., Ltd.) at 20°C by the Wilhelmy method.

[0156] [Table 4]

[0157] <7> evaluation <7-1>Drying resistance evaluation For each of the inkjet inks in Examples C1-C6 and Comparative Examples C1-C3, 0.05 mL of ink was dropped onto a glass plate and left at 40°C for 1 day to dry. After drying, the glass plate was immersed in the corresponding inkjet ink, removed after 10 minutes, and the traces of the dried ink droplets were visually observed and evaluated according to the following criteria.

[0158] A: All traces of ink droplets have disappeared. B: In terms of area percentage, more than 0% but less than 5% of the ink droplet marks remained. C: In terms of area percentage, 5% to less than 25% of the ink droplet trace remains. D: In terms of area percentage, more than 25% of the ink droplet trace remains.

[0159] <7-2> Evaluation of storage stability based on viscosity stability The inkjet inks of Examples C1-C6 and Comparative Examples C1-C3 were each placed in sample containers and left at 70°C for one week. The viscosity at 20°C was then measured and compared with the viscosity at 20°C of the inkjet ink immediately after manufacturing, and evaluated according to the following criteria. A smaller viscosity fluctuation rate indicates better dispersion stability of the dispersed phase.

[0160] A: Viscosity fluctuation rate from immediately after manufacturing is less than 10%. B: Viscosity fluctuation rate from immediately after manufacturing is 10% or more but less than 20%. C: Viscosity fluctuation rate from immediately after manufacturing is 20% or more. D: Aggregation and gelation occur, making viscosity measurement impossible.

[0161] <7-3> Evaluation of storage stability based on particle size stability The inkjet inks of Examples C1-C6 and Comparative Examples C1-C3 were each placed in sample containers and left at 70°C for one week. The average particle size of the dispersed phase contained in the inkjet ink was then determined at 20°C and compared with the average particle size of the dispersed phase contained in the inkjet ink immediately after manufacturing. The evaluation was conducted according to the following criteria. A smaller variation in the particle size of the dispersed phase indicates superior dispersion stability. In this specification, unless otherwise specified, the average particle size refers to the average particle size based on volume. The average particle size was determined using Microtrac UPA (manufactured by Nikkiso Co., Ltd.).

[0162] A: The variation rate of the average particle size of the dispersed phase immediately after manufacturing is less than 15%. B: The variation rate of the average particle size of the dispersed phase from immediately after manufacturing is 15% or more but less than 30%. C: The variation rate of the average particle size of the dispersed phase from immediately after manufacturing is 30% or more. D: Aggregation and gelation occur, making it impossible to measure the particle size of the dispersed phase. The evaluation results described above are summarized in Table 5.

[0163] [Table 5]

[0164] As is clear from Table 5, the present invention yielded excellent results in both drought resistance and storage stability. In contrast, each comparative example failed to achieve both drought resistance and storage stability, and unsatisfactory results were not obtained.

[0165] In particular, in Comparative Example C1, insufficient solubility of the polyester in the dispersant-containing solution was observed. Therefore, it is presumed that the amount of polyester adsorbed onto the colorant during dispersion preparation was insufficient, resulting in inadequate dispersion stability of the dispersed phase. Furthermore, since the only water-soluble group in the polyester was a sulfo group, it is presumed that insufficient affinity with the additive led to a breakdown of the colorant dispersion, resulting in poor drought resistance and storage stability.

[0166] Furthermore, while Comparative Example C2, like Example C6, contains the polyester from Synthesis Example 6, the logP of the polyol is 2.1, which is outside the range of -2.0 to 0.0. Therefore, it is presumed that the polyol's lipophilicity was too high, preventing sufficient exchange between the solvent adsorbed on the colorant and the polyester, resulting in insufficient dispersibility of the colorant. Consequently, it exhibited significantly inferior drying resistance and storage stability compared to Example C6.

[0167] Furthermore, while Comparative Example C3, like Example C6, contains the polyester from Synthesis Example 6, the logP of the polyol is -2.3, which falls outside the range of -2.0 to 0.0. Therefore, it is presumed that the low lipophilicity of the polyol prevented the solvent from penetrating between the colorant powders during grinding, resulting in insufficient grinding and poor dispersibility of the colorant, leading to significantly inferior drying resistance and storage stability compared to Example C6.

Claims

1. It contains polyester as a dispersant, water, and a solvent. The polyester has carboxyl groups and sulfo groups that do not constitute ester bonds. The solvent contains a polyol having a logP of -2.0 or more and 0.0 or less. The ratio of the content of monomers having carboxyl groups to the content of monomers having sulfo groups in the polyester is 50% or more and 200% or less in molar ratio. The aforementioned polyester contains a water-insoluble aromatic monomer that does not have a water-soluble group and has an aromatic ring, A dispersant-containing liquid for inkjet compositions, wherein the content of the non-water-soluble aromatic monomer relative to the total monomers constituting the polyester is 25 mol% or more and 75 mol% or less.

2. The dispersant-containing liquid according to claim 1, further comprising a monovalent inorganic base and a water-soluble organic amine.

3. The dispersant-containing liquid according to claim 2, wherein the water-soluble organic amine is a hydroxyamine.

4. The dispersant-containing liquid according to any one of claims 1 to 3, wherein the content of the polyol per 100.0 parts by mass of the polyester is 1.0 part by mass or more and 50.0 parts by mass or less.

5. It contains polyester as a dispersant, water, a dispersed phase, and a solvent. The polyester has carboxyl groups and sulfo groups that do not constitute ester bonds. The solvent contains a polyol having a logP of -2.0 or more and 0.0 or less. The ratio of the content of monomers having carboxyl groups to the content of monomers having sulfo groups in the polyester is 50% or more and 200% or less in molar ratio. The aforementioned polyester contains a water-insoluble aromatic monomer that does not have a water-soluble group and has an aromatic ring, An inkjet composition wherein the content of the water-insoluble aromatic monomer relative to the total monomers constituting the polyester is 25 mol% or more and 75 mol% or less.

6. The inkjet composition according to claim 5, wherein the dispersed phase is either a disperse dye or an oil-soluble dye.

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